Sample records for abnormal pore pressure

  1. Abnormal formation velocities and applications to pore pressure prediction

    NASA Astrophysics Data System (ADS)

    Liu, Libin; Shen, Guoqiang; Wang, Zhentao; Yang, Hongwei; Han, Hongwei; Cheng, Yuanfeng

    2018-06-01

    The pore pressure is a vital concept to the petroleum industry and cannot be ignored by either reservoir engineers or geoscientists. Based on theoretical analyses of effective stresses and the grain packing model, a new equation is proposed for predicting pore pressures from formation velocity data. The predictions agree well with both measured pressures and estimations using Eaton's empirical equation, but the application of the new equation to seismic data is simple and convenient. One application example shows that the identification of sweet spots is much easier using pore pressure data than with inverted seismic velocity data. In another application example using field seismic data, a distribution of overpressured strata is revealed, which is a crucial clue for petroleum generation and accumulation. Still, the accuracy of pore pressure prediction is hardly always guaranteed, mainly owing to the complexity of the real geology and the suitability of specific assumptions about the underlying rock physics.

  2. Abnormally high formation pressures, Potwar Plateau, Pakistan

    USGS Publications Warehouse

    Law, B.E.; Shah, S.H.A.; Malik, M.A.

    1998-01-01

    Abnormally high formation pressures in the Potwar Plateau of north-central Pakistan are major obstacles to oil and gas exploration. Severe drilling problems associated with high pressures have, in some cases, prevented adequate evaluation of reservoirs and significantly increased drilling costs. Previous investigations of abnormal pressure in the Potwar Plateau have only identified abnormal pressures in Neogene rocks. We have identified two distinct pressure regimes in this Himalayan foreland fold and thrust belt basin: one in Neogene rocks and another in pre-Neogene rocks. Pore pressures in Neogene rocks are as high as lithostatic and are interpreted to be due to tectonic compression and compaction disequilibrium associated with high rates of sedimentation. Pore pressure gradients in pre-Neogene rocks are generally less than those in Neogene rocks, commonly ranging from 0.5 to 0.7 psi/ft (11.3 to 15.8 kPa/m) and are most likely due to a combination of tectonic compression and hydrocarbon generation. The top of abnormally high pressure is highly variable and doesn't appear to be related to any specific lithologic seal. Consequently, attempts to predict the depth to the top of overpressure prior to drilling are precluded.

  3. Two innovative pore pressure calculation methods for shallow deep-water formations

    NASA Astrophysics Data System (ADS)

    Deng, Song; Fan, Honghai; Liu, Yuhan; He, Yanfeng; Zhang, Shifeng; Yang, Jing; Fu, Lipei

    2017-11-01

    There are many geological hazards in shallow formations associated with oil and gas exploration and development in deep-water settings. Abnormal pore pressure can lead to water flow and gas and gas hydrate accumulations, which may affect drilling safety. Therefore, it is of great importance to accurately predict pore pressure in shallow deep-water formations. Experience over previous decades has shown, however, that there are not appropriate pressure calculation methods for these shallow formations. Pore pressure change is reflected closely in log data, particularly for mudstone formations. In this paper, pore pressure calculations for shallow formations are highlighted, and two concrete methods using log data are presented. The first method is modified from an E. Philips test in which a linear-exponential overburden pressure model is used. The second method is a new pore pressure method based on P-wave velocity that accounts for the effect of shallow gas and shallow water flow. Afterwards, the two methods are validated using case studies from two wells in the Yingqiong basin. Calculated results are compared with those obtained by the Eaton method, which demonstrates that the multi-regression method is more suitable for quick prediction of geological hazards in shallow layers.

  4. Quantification of subsurface pore pressure through IODP drilling

    NASA Astrophysics Data System (ADS)

    Saffer, D. M.; Flemings, P. B.

    2010-12-01

    It is critical to understand the magnitude and distribution of subsurface pore fluid pressure: it controls effective stress and thus mechanical strength, slope stability, and sediment compaction. Elevated pore pressures also drive fluid flows that serve as agents of mass, solute, and heat fluxes. The Ocean Drilling Program (ODP) and Integrated Ocean Drilling Program (IODP) have provided important avenues to quantify pore pressure in a range of geologic and tectonic settings. These approaches include 1) analysis of continuous downhole logs and shipboard physical properties data to infer compaction state and in situ pressure and stress, 2) laboratory consolidation testing of core samples collected by drilling, 3) direct downhole measurements using pore pressure probes, 3) pore pressure and stress measurements using downhole tools that can be deployed in wide diameter pipe recently acquired for riser drilling, and 4) long-term monitoring of formation pore pressure in sealed boreholes within hydraulically isolated intervals. Here, we summarize key advances in quantification of subsurface pore pressure rooted in scientific drilling, highlighting with examples from subduction zones, the Gulf of Mexico, and the New Jersey continental shelf. At the Nankai, Costa Rican, and Barbados subduction zones, consolidation testing of cores samples, combined with analysis of physical properties data, indicates that even within a few km landward of the trench, pore pressures in and below plate boundary décollement zones reach a significant fraction of the lithostatic load (λ*=0.25-0.91). These results document a viable and quantifiable mechanism to explain the mechanical weakness of subduction décollements, and are corroborated by a small number of direct measurements in sealed boreholes and by inferences from seismic reflection data. Recent downhole measurements conducted during riser drilling using the modular formation dynamics tester wireline tool (MDT) in a forearc basin ~50

  5. Pore fluid pressure and the seismic cycle

    NASA Astrophysics Data System (ADS)

    French, M. E.; Zhu, W.; Hirth, G.; Belzer, B.

    2017-12-01

    In the brittle crust, the critical shear stress required for fault slip decreases with increasing pore fluid pressures according to the effective stress criterion. As a result, higher pore fluid pressures are thought to promote fault slip and seismogenesis, consistent with observations that increasing fluid pressure as a result of wastewater injection is correlated with increased seismicity. On the other hand, elevated pore fluid pressure is also proposed to promote slow stable failure rather than seismicity along some fault zones, including during slow slip in subduction zones. Here we review recent experimental evidence for the roles that pore fluid pressure and the effective stress play in controlling fault slip behavior. Using two sets of experiments on serpentine fault gouge, we show that increasing fluid pressure does decrease the shear stress for reactivation under brittle conditions. However, under semi-brittle conditions as expected near the base of the seismogenic zone, high pore fluid pressures are much less effective at reducing the shear stress of reactivation even though deformation is localized and frictional. We use an additional study on serpentinite to show that cohesive fault rocks, potentially the product of healing and cementation, experience an increase in fracture energy during faulting as fluid pressures approach lithostatic, which can lead to more stable failure. Structural observations show that the increased fracture energy is associated with a greater intensity of transgranular fracturing and delocalization of deformation. Experiments on several lithologies indicate that the stabilizing effect of fluid pressure occurs independent of rock composition and hydraulic properties. Thus, high pore fluid pressures have the potential to either enhance seismicity or promote stable faulting depending on pressure, temperature, and fluid pressure conditions. Together, the results of these studies indicate that pore fluid pressure promotes

  6. Abnormal pressures as hydrodynamic phenomena

    USGS Publications Warehouse

    Neuzil, C.E.

    1995-01-01

    So-called abnormal pressures, subsurface fluid pressures significantly higher or lower than hydrostatic, have excited speculation about their origin since subsurface exploration first encountered them. Two distinct conceptual models for abnormal pressures have gained currency among earth scientists. The static model sees abnormal pressures generally as relict features preserved by a virtual absence of fluid flow over geologic time. The hydrodynamic model instead envisions abnormal pressures as phenomena in which flow usually plays an important role. This paper develops the theoretical framework for abnormal pressures as hydrodynamic phenomena, shows that it explains the manifold occurrences of abnormal pressures, and examines the implications of this approach. -from Author

  7. Abnormal pressure in hydrocarbon environments

    USGS Publications Warehouse

    Law, B.E.; Spencer, C.W.

    1998-01-01

    Abnormal pressures, pressures above or below hydrostatic pressures, occur on all continents in a wide range of geological conditions. According to a survey of published literature on abnormal pressures, compaction disequilibrium and hydrocarbon generation are the two most commonly cited causes of abnormally high pressure in petroleum provinces. In young (Tertiary) deltaic sequences, compaction disequilibrium is the dominant cause of abnormal pressure. In older (pre-Tertiary) lithified rocks, hydrocarbon generation, aquathermal expansion, and tectonics are most often cited as the causes of abnormal pressure. The association of abnormal pressures with hydrocarbon accumulations is statistically significant. Within abnormally pressured reservoirs, empirical evidence indicates that the bulk of economically recoverable oil and gas occurs in reservoirs with pressure gradients less than 0.75 psi/ft (17.4 kPa/m) and there is very little production potential from reservoirs that exceed 0.85 psi/ft (19.6 kPa/m). Abnormally pressured rocks are also commonly associated with unconventional gas accumulations where the pressuring phase is gas of either a thermal or microbial origin. In underpressured, thermally mature rocks, the affected reservoirs have most often experienced a significant cooling history and probably evolved from an originally overpressured system.

  8. Temperature and Pressure from Collapsing Pores in HMX

    NASA Astrophysics Data System (ADS)

    Hardin, D. Barrett

    2017-06-01

    The thermal and mechanical response of collapsing voids in HMX is analyzed. In this work, the focus is simulating the temperature and pressure fields arising from isolated, idealized pores as they collapse in the presence of a shock. HMX slabs are numerically generated which contain a single pore, isolated from the boundaries to remove all wave reflections. In order to understand the primary pore characteristics leading to temperature rise, a series of 2D, plane strain simulations are conducted on HMX slabs containing both cylindrical and elliptical pores of constant size equal to the area of a circular pore with a 1 micron diameter. Each of these pore types is then subjected to shock pressures ranging from a weak shock that is unable to fully collapse the pore to a strong shock which overwhelms the tendency for localization. Results indicate that as shock strength increases, pore collapse phenomenology for a cylindrical pore transitions from a mode dominated by localized melt cracking to an idealized hydrodynamic pore collapse. For the case of elliptical pores, the orientation causing maximum temperature and pressure rise is found. The relative heating in elliptical pores is then quantified as a function of pore orientation and aspect ratio for a pore of a given area. Distribution A: Distribution unlimited. (96TW 2017-0036).

  9. Surge dynamics coupled to pore-pressure evolution in debris flows

    USGS Publications Warehouse

    Savage, S.B.; Iverson, R.M.; ,

    2003-01-01

    Temporally and spatially varying pore-fluid pressures exert strong controls on debris-flow motion by mediating internal and basal friction at grain contacts. We analyze these effects by deriving a one-dimensional model of pore-pressure diffusion explicitly coupled to changes in debris-flow thickness. The new pore-pressure equation is combined with Iverson's (1997) extension of the depth-averaged Savage-Hutter (1989, 1991) granular avalanche equations to predict motion of unsteady debris-flow surges with evolving pore-pressure distributions. Computational results illustrate the profound effects of pore-pressure diffusivities on debris-flow surge depths and velocities. ?? 2003 Millpress,.

  10. Pore pressure migration during hydraulic stimulation due to permeability enhancement by low-pressure subcritical fracture slip

    NASA Astrophysics Data System (ADS)

    Mukuhira, Yusuke; Moriya, Hirokazu; Ito, Takatoshi; Asanuma, Hiroshi; Häring, Markus

    2017-04-01

    Understanding the details of pressure migration during hydraulic stimulation is important for the design of an energy extraction system and reservoir management, as well as for the mitigation of hazardous-induced seismicity. Based on microseismic and regional stress information, we estimated the pore pressure increase required to generate shear slip on an existing fracture during stimulation. Spatiotemporal analysis of pore pressure migration revealed that lower pore pressure migrates farther and faster and that higher pore pressure migrates more slowly. These phenomena can be explained by the relationship between fracture permeability and stress state criticality. Subcritical fractures experience shear slip following smaller increases of pore pressure and promote migration of pore pressure because of their enhanced permeability. The difference in migration rates between lower and higher pore pressures suggests that the optimum wellhead pressure is the one that can stimulate relatively permeable fractures, selectively. Its selection optimizes economic benefits and minimizes seismic risk.

  11. Study of pore pressure reaction on hydraulic fracturing

    NASA Astrophysics Data System (ADS)

    Trimonova, Mariia; Baryshnikov, Nikolay; Turuntaev, Sergey; Zenchenko, Evgeniy; Zenchenko, Petr

    2017-04-01

    We represent the results of the experimental study of the hydraulic fracture propagation influence on the fluid pore pressure. Initial pore pressure was induced by injection and production wells. The experiments were carried out according to scaling analysis based on the radial model of the fracture. All required geomechanical and hydrodynamical properties of a sample were derived from the scaling laws. So, gypsum was chosen as a sample material and vacuum oil as a fracturing fluid. The laboratory setup allows us to investigate the samples of cylindrical shape. It can be considered as an advantage in comparison with standard cubic samples, because we shouldn't consider the stress field inhomogeneity induced by the corners. Moreover, we can set 3D-loading by this setting. Also the sample diameter is big enough (43cm) for placing several wells: the fracturing well in the center and injection and production wells on two opposite sides of the central well. The experiment consisted of several stages: a) applying the horizontal pressure; b) applying the vertical pressure; c) water solution injection in the injection well with a constant pressure; d) the steady state obtaining; e) the oil injection in the central well with a constant rate. The pore pressure was recorded in the 15 points along bottom side of the sample during the whole experiment. We observe the pore pressure change during all the time of the experiment. First, the pore pressure changed due to water injection. Then we began to inject oil in the central well. We compared the obtained experimental data on the pore pressure changes with the solution of the 2D single-phase equation of pore-elasticity, and we found significant difference. The variation of the equation parameters couldn't help to resolve the discrepancy. After the experiment, we found that oil penetrated into the sample before and after the fracture initiation. This fact encouraged us to consider another physical process - the oil

  12. Upscaling pore pressure-dependent gas permeability in shales

    NASA Astrophysics Data System (ADS)

    Ghanbarian, Behzad; Javadpour, Farzam

    2017-04-01

    Upscaling pore pressure dependence of shale gas permeability is of great importance and interest in the investigation of gas production in unconventional reservoirs. In this study, we apply the Effective Medium Approximation, an upscaling technique from statistical physics, and modify the Doyen model for unconventional rocks. We develop an upscaling model to estimate the pore pressure-dependent gas permeability from pore throat size distribution, pore connectivity, tortuosity, porosity, and gas characteristics. We compare our adapted model with six data sets: three experiments, one pore-network model, and two lattice-Boltzmann simulations. Results showed that the proposed model estimated the gas permeability within a factor of 3 of the measurements/simulations in all data sets except the Eagle Ford experiment for which we discuss plausible sources of discrepancies.

  13. Compaction and Permeability Reduction of Castlegate Sandstone under Pore Pressure Cycling

    NASA Astrophysics Data System (ADS)

    Bauer, S. J.

    2014-12-01

    We investigate time-dependent compaction and permeability changes by cycling pore pressure with application to compressed air energy storage (CAES) in a reservoir. Preliminary experiments capture the impacts of hydrostatic stress, pore water pressure, pore pressure cycling, chemical, and time-dependent considerations near a borehole in a CAES reservoir analog. CAES involves creating an air bubble in a reservoir. The high pressure bubble serves as a mechanical battery to store potential energy. When there is excess grid energy, bubble pressure is increased by air compression, and when there is energy needed on the grid, stored air pressure is released through turbines to generate electricity. The analog conditions considered are depth ~1 km, overburden stress ~20 MPa and a pore pressure ~10MPa. Pore pressure is cycled daily or more frequently between ~10 MPa and 6 MPa, consistent with operations of a CAES facility at this depth and may continue for operational lifetime (25 years). The rock can vary from initially fully-to-partially saturated. Pore pressure cycling changes the effective stress.Jacketed, room temperature tap water-saturated samples of Castlegate Sandstone are hydrostatically confined (20 MPa) and subjected to a pore pressure resulting in an effective pressure of ~10 MPa. Pore pressure is cycled between 6 to 10 MPa. Sample displacement measurements yielded determinations of volumetric strain and from water flow measurements permeability was determined. Experiments ran for two to four weeks, with 2 to 3 pore pressure cycles per day. The Castlegate is a fluvial high porosity (>20%) primarily quartz sandstone, loosely calcite cemented, containing a small amount of clay.Pore pressure cycling induces compaction (~.1%) and permeability decreases (~20%). The results imply that time-dependent compactive processes are operative. The load path, of increasing and decreasing pore pressure, may facilitate local loosening and grain readjustments that results in the

  14. Capillary pressure-saturation relationships for porous granular materials: Pore morphology method vs. pore unit assembly method

    NASA Astrophysics Data System (ADS)

    Sweijen, Thomas; Aslannejad, Hamed; Hassanizadeh, S. Majid

    2017-09-01

    In studies of two-phase flow in complex porous media it is often desirable to have an estimation of the capillary pressure-saturation curve prior to measurements. Therefore, we compare in this research the capability of three pore-scale approaches in reproducing experimentally measured capillary pressure-saturation curves. To do so, we have generated 12 packings of spheres that are representative of four different glass-bead packings and eight different sand packings, for which we have found experimental data on the capillary pressure-saturation curve in the literature. In generating the packings, we matched the particle size distributions and porosity values of the granular materials. We have used three different pore-scale approaches for generating the capillary pressure-saturation curves of each packing: i) the Pore Unit Assembly (PUA) method in combination with the Mayer and Stowe-Princen (MS-P) approximation for estimating the entry pressures of pore throats, ii) the PUA method in combination with the hemisphere approximation, and iii) the Pore Morphology Method (PMM) in combination with the hemisphere approximation. The three approaches were also used to produce capillary pressure-saturation curves for the coating layer of paper, used in inkjet printing. Curves for such layers are extremely difficult to determine experimentally, due to their very small thickness and the presence of extremely small pores (less than one micrometer in size). Results indicate that the PMM and PUA-hemisphere method give similar capillary pressure-saturation curves, because both methods rely on a hemisphere to represent the air-water interface. The ability of the hemisphere approximation and the MS-P approximation to reproduce correct capillary pressure seems to depend on the type of particle size distribution, with the hemisphere approximation working well for narrowly distributed granular materials.

  15. Pore pressure control on faulting behavior in a block-gouge system

    NASA Astrophysics Data System (ADS)

    Yang, Z.; Juanes, R.

    2016-12-01

    Pore fluid pressure in a fault zone can be altered by natural processes (e.g., mineral dehydration and thermal pressurization) and industrial operations involving subsurface fluid injection/extraction for the development of energy and water resources. However, the effect of pore pressure change on the stability and slip motion of a preexisting geologic fault remain poorly understood; yet they are critical for the assessment of seismic risk. In this work, we develop a micromechanical model to investigate the effect of pore pressure on faulting behavior. The model couples pore network fluid flow and mechanics of the solid grains. We conceptualize the fault zone as a gouge layer sandwiched between two blocks; the block material is represented by a group of contact-bonded grains and the gouge is composed of unbonded grains. A pore network is extracted from the particulate pack of the block-gouge system with pore body volumes and pore throat conductivities calculated rigorously based on the geometry of the local pore space. Pore fluid exerts pressure force onto the grains, the motion of which is solved using the discrete element method (DEM). The model updates the pore network regularly in response to deformation of the solid matrix. We study the fault stability in the presence of a pressure inhomogeneity (gradient) across the gouge layer, and compare it with the case of homogeneous pore pressure. We consider both normal and thrust faulting scenarios with a focus on the onset of shear failure along the block-gouge interfaces. Numerical simulations show that the slip behavior is characterized by intermittent dynamics, which is evident in the number of slipping contacts at the block-gouge interfaces and the total kinetic energy of the gouge particles. Numerical results also show that, for the case of pressure inhomogeneity, the onset of slip occurs earlier for the side with higher pressure, and that this onset appears to be controlled by the maximum pressure of both sides

  16. Regulation of landslide motion by dilatancy and pore pressure feedback

    USGS Publications Warehouse

    Iverson, R.M.

    2005-01-01

    A new mathematical model clarifies how diverse styles and rates of landslide motion can result from regulation of Coulomb friction by dilation or contraction of water-saturated basal shear zones. Normalization of the model equations shows that feedback due to coupling between landslide motion, shear zone volume change, and pore pressure change depends on a single dimensionless parameter ??, which, in turn, depends on the dilatancy angle ?? and the intrinsic timescales for pore pressure generation and dissipation. If shear zone soil contracts during slope failure, then ?? 0, and negative feedback permits slow, steady landslide motion to occur while positive pore pressure is supplied by rain infiltration. Steady state slip velocities v0 obey v0 = -(K/??) p*e, where K is the hydraulic conductivity and p*e is the normalized (dimensionless) negative pore pressure generated by dilation. If rain infiltration and attendant pore pressure growth continue unabated, however, their influence ultimately overwhelms the stabilizing influence of negative p*e. Then, unbounded landslide acceleration occurs, accentuated by an instability that develops if ?? diminishes as landslide motion proceeds. Nonetheless, numerical solutions of the model equations show that slow, nearly steady motion of a clay-rich landslide may persist for many months as a result of negative pore pressure feedback that regulates basal Coulomb friction. Similarly stabilized motion is less likely to occur in sand-rich landslides that are characterized by weaker negative feedback.

  17. Effects of intermediate wettability on entry capillary pressure in angular pores.

    PubMed

    Rabbani, Harris Sajjad; Joekar-Niasar, Vahid; Shokri, Nima

    2016-07-01

    Entry capillary pressure is one of the most important factors controlling drainage and remobilization of the capillary-trapped phases as it is the limiting factor against the two-phase displacement. It is known that the entry capillary pressure is rate dependent such that the inertia forces would enhance entry of the non-wetting phase into the pores. More importantly the entry capillary pressure is wettability dependent. However, while the movement of a meniscus into a strongly water-wet pore is well-defined, the invasion of a meniscus into a weak or intermediate water-wet pore especially in the case of angular pores is ambiguous. In this study using OpenFOAM software, high-resolution direct two-phase flow simulations of movement of a meniscus in a single capillary channel are performed. Interface dynamics in angular pores under drainage conditions have been simulated under constant flow rate boundary condition at different wettability conditions. Our results shows that the relation between the half corner angle of pores and contact angle controls the temporal evolution of capillary pressure during the invasion of a pore. By deviating from pure water-wet conditions, a dip in the temporal evolution of capillary pressure can be observed which will be pronounced in irregular angular cross sections. That enhances the pore invasion with a smaller differential pressure. The interplay between the contact angle and pore geometry can have significant implications for enhanced remobilization of ganglia in intermediate contact angles in real porous media morphologies, where pores are very heterogeneous with small shape factors. Copyright © 2016 The Authors. Published by Elsevier Inc. All rights reserved.

  18. Detecting Pore Fluid Pressure Changes by Using the Vp/Vs Ratio

    NASA Astrophysics Data System (ADS)

    Vanorio, T.; Mavko, G.

    2006-12-01

    A central problem in studies aimed at predicting the dynamic behavior of faults is monitoring and quantifying fluid changes in areas prone to overpressure. Experimental and modeling studies show the Vp/Vs ratio to be a good determinant of the saturation state of a rock formation as well as of its inner pore pressure condition. Dectecting pore pressure changes depends, among other causes, on the reliability of laboratory data to calibrate the in-situ measured velocities. Ideally, laboratory experiments performed under controlled conditions would identify the fundamental mechanisms responsible for changes in the measured acoustic properties. However, technical limitations in the laboratory together with the assumptions driving the experimental and modeling approaches rise spouriuos mechanisms which hinder our present understanding of the actual role of high pore pressure on the elastic and poroelastic parameters. Critical issues unclude: a) the frequencies used in the laboratory are responsible for high-frequency fluid effects which induce velocity dispersion. As a result, both the effective stress parameter and velocities (and their pressure-dependence) estimated from high- frequency ultrasonic data are different from those applicable to crustal low frequency wave propagation; b) laboratory measurements made at dry, drained conditions are assumed to mimic those in gas pressured rocks. However, in dry, drained conditions, no pore pressure is exerted in the pore space, and the pore gas is infinitely compressible; c) when using room-dry, drained measurements as the baseline to model pressured rock formations, the unloading path (i.e. decreasing confining pressure) is supposed to mimic the inflationary path due to pore pressure increase. Doing so, it is assumed that the amount of crack opening due to pore pressure is equal to that of crack closure caused by the overburden stress and thus, the effective stress coefficient is implicitely assumed equal to 1. To minimize

  19. Pore Fluid Pressure Development in Compacting Fault Gouge in Theory, Experiments, and Nature

    NASA Astrophysics Data System (ADS)

    Faulkner, D. R.; Sanchez-Roa, C.; Boulton, C.; den Hartog, S. A. M.

    2018-01-01

    The strength of fault zones is strongly dependent on pore fluid pressures within them. Moreover, transient changes in pore fluid pressure can lead to a variety of slip behavior from creep to unstable slip manifested as earthquakes or slow slip events. The frictional properties of low-permeability fault gouge in nature and experiment can be affected by pore fluid pressure development through compaction within the gouge layer, even when the boundaries are drained. Here the conditions under which significant pore fluid pressures develop are analyzed analytically, numerically, and experimentally. Friction experiments on low-permeability fault gouge at different sliding velocities show progressive weakening as slip rate is increased, indicating that faster experiments are incapable of draining the pore fluid pressure produced by compaction. Experiments are used to constrain the evolution of the permeability and pore volume needed for numerical modeling of pore fluid pressure build up. The numerical results are in good agreement with the experiments, indicating that the principal physical processes have been considered. The model is used to analyze the effect of pore fluid pressure transients on the determination of the frictional properties, illustrating that intrinsic velocity-strengthening behavior can appear velocity weakening if pore fluid pressure is not given sufficient time to equilibrate. The results illustrate that care must be taken when measuring experimentally the frictional characteristics of low-permeability fault gouge. The contribution of compaction-induced pore fluid pressurization leading to weakening of natural faults is considered. Cyclic pressurization of pore fluid within fault gouge during successive earthquakes on larger faults may reset porosity and hence the capacity for compaction weakening.

  20. Preliminary Investigation on the Behavior of Pore Air Pressure During Rainfall Infiltration

    NASA Astrophysics Data System (ADS)

    Ashraf Mohamad Ismail, Mohd; Min, Ng Soon; Hasliza Hamzah, Nur; Hazreek Zainal Abidin, Mohd; Madun, Aziman; Tajudin, Saiful Azhar Ahmad

    2018-04-01

    This paper focused on the preliminary investigation of pore air pressure behaviour during rainfall infiltration in order to substantiate the mechanism of rainfall induced slope failure. The actual behaviour or pore air pressure during infiltration is yet to be clearly understood as it is regularly assumed as atmospheric. Numerical modelling of one dimensional (1D) soil column was utilized in this study to provide a preliminary insight of this highlighted uncertainty. Parametric study was performed by using rainfall intensities of 1.85 x 10-3m/s and 1.16 x 10-4m/s applied on glass beads to simulate intense and modest rainfall conditions. Analysis results show that the high rainfall intensity causes more development of pore air pressure compared to low rainfall intensity. This is because at high rainfall intensity, the rainwater cannot replace the pore air smoothly thus confining the pore air. Therefore, the effect of pore air pressure has to be taken into consideration particularly during heavy rainfall.

  1. High-pressure alchemy on a small-pore zeolite

    NASA Astrophysics Data System (ADS)

    Lee, Y.

    2011-12-01

    While an ever-expanding variety of zeolites with a wide range of framework topology is available, it is desirable to have a way to tailor the chemistry of the zeolitic nanopores for a given framework topology via controlling both the coordination-inclusion chemistry and framework distortion/relaxation. This is, however, subjected to the ability of a zeolitic nanopore to allow the redistribution of cations-water assembly and/or insertion of foreign molecules into the pores and channels. Small-pore zeolites such as natrolite (Na16Al16Si24O80x16H2O), however, have been known to show very limited capacity for any changes in the confinement chemistry. We have recently shown that various cation-exchanged natrolites can be prepared under modest conditions from natural sodium natrolite and exhibit cation-dependent volume expansions by up to 18.5% via converting the elliptical channels into progressively circular ones. Here, we show that pressure can be used as a unique and clean tool to further manipulate the chemistry of the natrolite nanopores. Our recent crystallographic and spectroscopic studies of pressure-insertion of foreign molecules, trivalent-cation exchange under pressure, and pressure-induced inversion of cation-water coordination and pore geometry in various cation-exchanged natrolites will be presented.

  2. Numerical simulation of pore pressure changes in levee under flood conditions

    NASA Astrophysics Data System (ADS)

    Stanisz, Jacek; Borecka, Aleksandra; Pilecki, Zenon; Kaczmarczyk, Robert

    2017-11-01

    The article discusses the potential for using numerical simulation to assess the development of deformation and pore pressure changes in a levee as a result of the increase and decrease of the flood wave. The simulation made in FLAC 2D did not take into account the filter-erosion deformation associated with seepage in the levee. The simulations were carried out for a field experimental storage consisting of two combined levees, which was constructed with the help of homogeneous cohesive materials with different filtration coefficients. Calculated and measured pore pressure changes were analysed at 4 monitoring points. The water level was increased to 4 m in 96 hours and decreased in 120 hours. The characteristics of the calculated and measured pore pressure changes over time were similar. The maximum values of the calculated and measured pore pressure were almost identical. The only differences were the greater delay of the experimental levee response to changes in water level increase compared to the response of the numerical model. These differences were probably related to filtering-erosion effects during seepage in the levee.

  3. Pore Pressure and Stress Distributions Around a Hydraulic Fracture in Heterogeneous Rock

    NASA Astrophysics Data System (ADS)

    Gao, Qian; Ghassemi, Ahmad

    2017-12-01

    One of the most significant characteristics of unconventional petroleum bearing formations is their heterogeneity, which affects the stress distribution, hydraulic fracture propagation and also fluid flow. This study focuses on the stress and pore pressure redistributions during hydraulic stimulation in a heterogeneous poroelastic rock. Lognormal random distributions of Young's modulus and permeability are generated to simulate the heterogeneous distributions of material properties. A 3D fully coupled poroelastic model based on the finite element method is presented utilizing a displacement-pressure formulation. In order to verify the model, numerical results are compared with analytical solutions showing excellent agreements. The effects of heterogeneities on stress and pore pressure distributions around a penny-shaped fracture in poroelastic rock are then analyzed. Results indicate that the stress and pore pressure distributions are more complex in a heterogeneous reservoir than in a homogeneous one. The spatial extent of stress reorientation during hydraulic stimulations is a function of time and is continuously changing due to the diffusion of pore pressure in the heterogeneous system. In contrast to the stress distributions in homogeneous media, irregular distributions of stresses and pore pressure are observed. Due to the change of material properties, shear stresses and nonuniform deformations are generated. The induced shear stresses in heterogeneous rock cause the initial horizontal principal stresses to rotate out of horizontal planes.

  4. A new approximation for pore pressure accumulation in marine sediment due to water waves

    NASA Astrophysics Data System (ADS)

    Jeng, D.-S.; Seymour, B. R.; Li, J.

    2007-01-01

    The residual mechanism of wave-induced pore water pressure accumulation in marine sediments is re-examined. An analytical approximation is derived using a linear relation for pore pressure generation in cyclic loading, and mistakes in previous solutions (Int. J. Numer. Anal. Methods Geomech. 2001; 25:885-907; J. Offshore Mech. Arctic Eng. (ASME) 1989; 111(1):1-11) are corrected. A numerical scheme is then employed to solve the case with a non-linear relation for pore pressure generation. Both analytical and numerical solutions are verified with experimental data (Laboratory and field investigation of wave-sediment interaction. Joseph H. Defrees Hydraulics Laboratory, School of Civil and Environmental Engineering, Cornell University, Ithaca, NY, 1983), and provide a better prediction of pore pressure accumulation than the previous solution (J. Offshore Mech. Arctic Eng. (ASME) 1989; 111(1):1-11). The parametric study concludes that the pore pressure accumulation and use of full non-linear relation of pore pressure become more important under the following conditions: (1) large wave amplitude, (2) longer wave period, (3) shallow water, (4) shallow soil and (5) softer soils with a low consolidation coefficient. Copyright

  5. PBO Borehole Strainmeters and Pore Pressure Sensors: Recording Hydrological Strain Signals

    NASA Astrophysics Data System (ADS)

    Gottlieb, M. H.; Hodgkinson, K. M.; Mencin, D.; Henderson, D. B.; Johnson, W.; Van Boskirk, E.; Pyatt, C.; Mattioli, G. S.

    2017-12-01

    UNAVCO operates a network of 75 borehole strainmeters along the west coast of the United States and Vancouver Island, Canada as part of the Plate Boundary Observatory (PBO), the geodetic component of the NSF-funded Earthscope program. Borehole strainmeters are designed to detect variations in the strain field at the nanostrain level and can easily detect transient strains caused by aseismic creep events, Episodic Tremor and Slip (ETS) events and seismically induced co- and post-seimic signals. In 2016, one strainmeter was installed in an Oklahoma oil field to characterize in-situ deformation during CO2 injection. Twenty-three strainmeter sites also have pore pressure sensors to measure fluctuations in groundwater pressure. Both the strainmeter network and the pore pressure sensors provide unique data against which those using water-level measurements, GPS time-series or InSAR data can compare possible subsidence signals caused by groundwater withdrawal or fluid re-injection. Operating for 12 years, the PBO strainmeter and pore pressure network provides a long-term, continuous, 1-sps record of deformation. PBO deploys GTSM21 tensor strainmeters from GTSM Technologies, which consist of four horizontal strain gauges stacked vertically, at different orientations, within a single 2 m-long instrument. The strainmeters are typically installed at depths of 200 to 250 m and grouted into the bottom of 15 cm diameter boreholes. The pore pressure sensors are Digiquartz Depth Sensors from Paros Scientific. These sensors are installed in 2" PVC, sampling groundwater through a screened section 15 m above the co-located strainmeter. These sensors are also recording at 1-sps with a resolution in the hundredths of hPa. High-rate local barometric pressure data and low-rate rainfall data also available at all locations. PBO Strainmeter and pore pressure data are available in SEED, SAC-ASCII and time-stamped ASCII format from the IRIS Data Managements Center. Strainmeter data are

  6. Theoretical Analysis of Pore Pressure Diffusion in Some Basic Rock Mechanics Experiments

    NASA Astrophysics Data System (ADS)

    Braun, Philipp; Ghabezloo, Siavash; Delage, Pierre; Sulem, Jean; Conil, Nathalie

    2018-05-01

    Non-homogeneity of the pore pressure field in a specimen is an issue for characterization of the thermo-poromechanical behaviour of low-permeability geomaterials, as in the case of the Callovo-Oxfordian claystone ( k < 10-20 m2), a possible host rock for deep radioactive waste disposal in France. In tests with drained boundary conditions, excess pore pressure can result in significant errors in the measurement of material parameters. Analytical solutions are presented for the change in time of the pore pressure field in a specimen submitted to various loading paths and different rates. The pore pressure field in mechanical and thermal undrained tests is simulated with a 1D finite difference model taking into account the dead volume of the drainage system of the triaxial cell connected to the specimen. These solutions provide a simple and efficient tool for the estimation of the conditions that must hold for reliable determination of material parameters and for optimization of various test conditions to minimize the experimental duration, while keeping the measurement errors at an acceptable level.

  7. Using Advanced Tensiometers to Monitor Temporal Variations in Pore Pressure

    NASA Astrophysics Data System (ADS)

    Nichols, R. L.; Young, M. H.; Dixon, K. L.; Rossabi, J.; Hyde, W. K.; Holmes-Burns, H.

    2002-12-01

    The Savannah River Site has installed a comprehensive vadose zone monitoring system (VZMS) at it's low level radioactive waste disposal facility to collect the necessary information to calculate contaminant flux. The VZMS includes water content reflectometers, suction lysimeters, advanced tensiometers (ATs), water flux meters, access ports for neutron probes, and a tipping bucket rain gauge. Forty one ATs were installed from 1999 to 2001 at depths ranging from 2 to 60 feet and have been operated continuously. The installation depths were based on a hydrostatigraphic model developed from core logs, cone penetrometer logs, moisture content profiles, water retention curves model that were obtained during the phased installation of the VZMS. An AT consists of a porous cup installed at a prescribed depth with casing back to the surface and a pressure transducer that is lowered into the casing and connects with the porous cup. The pressure transducer transmits it's signal to a datalogger where the data is stored for future retrieval using a cellular phone communications package. Results from the 2 year operating period show that the AT calibrations are stable and t ATs are capable of extended monitoring of pore pressures in the 0 to 300 cm H2 O range. The ATs had sufficient resolution to detect the naturally occurring fluctuations in pore pressure (1 to 100 cm H2 O over 1 to 72 hours) that resulted from infiltration events at the site. The stable performance of the ATs combined with their ability to detect naturally occurring fluctuations in pore pressure make the ATs a useful tool in measuring temporal pore pressure variations for use in calibrating numerical models of fluid flow in variably saturated porous media.

  8. Variations of permeability and pore size distribution of porous media with pressure.

    PubMed

    Chen, Quan; Kinzelbach, Wolfgang; Ye, Chaohui; Yue, Yong

    2002-01-01

    Porosity and permeability of porous and fractured geological media decrease with the exploitation of formation fluids such as petroleum, natural gas, or ground water. This may result in ground subsidence and a decrease of recovery of petroleum, natural gas, or ground water. Therefore, an evaluation of the behavior of permeability and porosity under formation fluid pressure changes is important to petroleum and ground water industries. This study for the first time establishes a method, which allows for the measurement of permeability, porosity, and pore size distribution of cores simultaneously. From the observation of the pore size distribution by low-field nuclear magnetic resonance (NMR) relaxation time spectrometry the mechanisms of pressure-dependent porosity and permeability change can be derived. This information cannot be obtained by traditional methods. As the large-size pores or fractures contribute significantly to the permeability, their change consequently leads to a large permeability change. The contribution of fractures to permeability is even larger than that of pores. Thus, the permeability of the cores with fractures decreased more than that of cores without fractures during formation pressure decrease. Furthermore, it did not recover during formation pressure increase. It can be concluded that in fractures, mainly plastic deformation takes place, while matrix pores mainly show elastic deformation. Therefore, it is very important to keep an appropriate formation fluid pressure during the exploitation of ground water and petroleum in a fractured formation.

  9. Influence of pore pressure change on coseismic volumetric strain

    USGS Publications Warehouse

    Wang, Chi-Yuen; Barbour, Andrew J.

    2017-01-01

    Coseismic strain is fundamentally important for understanding crustal response to changes of stress after earthquakes. The elastic dislocation model has been widely applied to interpreting observed shear deformation caused by earthquakes. The application of the same theory to interpreting volumetric strain, however, has met with difficulty, especially in the far field of earthquakes. Predicted volumetric strain with dislocation model often differs substantially, and sometimes of opposite signs, from observed coseismic volumetric strains. The disagreement suggests that some processes unaccounted for by the dislocation model may occur during earthquakes. Several hypotheses have been suggested, but none have been tested quantitatively. In this paper we first examine published data to highlight the difference between the measured and calculated static coseismic volumetric strains; we then use these data to provide quantitative test of the model that the disagreement may be explained by the change of pore pressure in the shallow crust. The test allows us to conclude that coseismic change of pore pressure may be an important mechanism for coseismic crustal strain and, in the far field, may even be the dominant mechanism. Thus in the interpretation of observed coseismic crustal strain, one needs to account not only for the elastic strain due to fault rupture but also for the strain due to coseismic change of pore pressure.

  10. Pore Pressure Distribution and Flank Instability in Hydrothermally Altered Stratovolcanoes

    NASA Astrophysics Data System (ADS)

    Ball, J. L.; Taron, J.; Hurwitz, S.; Reid, M. E.

    2015-12-01

    Field and geophysical investigations of stratovolcanoes with long-lived hydrothermal systems commonly reveal that initially permeable regions (such as brecciated layers of pyroclastic material) can become both altered and water-bearing. Hydrothermal alteration in these regions, including clay formation, can turn them into low-permeability barriers to fluid flow, which could increase pore fluid pressures resulting in flank slope instability. We examined elevated pore pressure conditions using numerical models of hydrothermal flow in stratovolcanoes, informed by geophysical data about internal structures and deposits. Idealized radially symmetric meshes were developed based on cross-sectional profiles and alteration/permeability structures of Cascade Range stratovolcanoes. We used the OpenGeoSys model to simulate variably saturated conditions in volcanoes heated only by regional heat fluxes, as well as 650°C intrusions at two km depth below the surface. Meteoric recharge was estimated from precipitation rates in the Cascade Range. Preliminary results indicate zones of elevated pore pressures form: 1) where slopes are underlain by continuous low-permeability altered layers, or 2) when the edifice has an altered core with saturated, less permeable limbs. The first scenario might control shallow collapses on the slopes above the altered layers. The second could promote deeper flank collapses that are initially limited to the summit and upper slopes, but could progress to the core of an edifice. In both scenarios, pore pressures can be further elevated by shallow intrusions, or evolve over longer time scales under forcing from regional heat flux. Geometries without confining low-permeability layers do not show these pressure effects. Our initial scenarios use radially symmetric models, but we are also simulating hydrothermal flow under real 3D geometries with asymmetric subsurface structures (Mount Adams). Simulation results will be used to inform 3D slope

  11. Temporal and Spatial Pore Water Pressure Distribution Surrounding a Vertical Landfill Leachate Recirculation Well

    PubMed Central

    Kadambala, Ravi; Townsend, Timothy G.; Jain, Pradeep; Singh, Karamjit

    2011-01-01

    Addition of liquids into landfilled waste can result in an increase in pore water pressure, and this in turn may increase concerns with respect to geotechnical stability of the landfilled waste mass. While the impact of vertical well leachate recirculation on landfill pore water pressures has been mathematically modeled, measurements of these systems in operating landfills have not been reported. Pressure readings from vibrating wire piezometers placed in the waste surrounding a liquids addition well at a full-scale operating landfill in Florida were recorded over a 2-year period. Prior to the addition of liquids, measured pore pressures were found to increase with landfill depth, an indication of gas pressure increase and decreasing waste permeability with depth. When liquid addition commenced, piezometers located closer to either the leachate injection well or the landfill surface responded more rapidly to leachate addition relative to those far from the well and those at deeper locations. After liquid addition stopped, measured pore pressures did not immediately drop, but slowly decreased with time. Despite the large pressures present at the bottom of the liquid addition well, much smaller pressures were measured in the surrounding waste. The spatial variation of the pressures recorded in this study suggests that waste permeability is anisotropic and decreases with depth. PMID:21655145

  12. Seismic attributes and advanced computer algorithm to predict formation pore pressure: Qalibah formation of Northwest Saudi Arabia

    NASA Astrophysics Data System (ADS)

    Nour, Abdoulshakour M.

    Oil and gas exploration professionals have long recognized the importance of predicting pore pressure before drilling wells. Pre-drill pore pressure estimation not only helps with drilling wells safely but also aids in the determination of formation fluids migration and seal integrity. With respect to the hydrocarbon reservoirs, the appropriate drilling mud weight is directly related to the estimated pore pressure in the formation. If the mud weight is lower than the formation pressure, a blowout may occur, and conversely, if it is higher than the formation pressure, the formation may suffer irreparable damage due to the invasion of drilling fluids into the formation. A simple definition of pore pressure is the pressure of the pore fluids in excess of the hydrostatic pressure. In this thesis, I investigated the utility of advance computer algorithm called Support Vector Machine (SVM) to learn the pattern of high pore pressure regime, using seismic attributes such as Instantaneous phase, t*Attenuation, Cosine of Phase, Vp/Vs ratio, P-Impedance, Reflection Acoustic Impedance, Dominant frequency and one well attribute (Mud-Weigh) as the learning dataset. I applied this technique to the over pressured Qalibah formation of Northwest Saudi Arabia. The results of my research revealed that in the Qalibah formation of Northwest Saudi Arabia, the pore pressure trend can be predicted using SVM with seismic and well attributes as the learning dataset. I was able to show the pore pressure trend at any given point within the geographical extent of the 3D seismic data from which the seismic attributes were derived. In addition, my results surprisingly showed the subtle variation of pressure within the thick succession of shale units of the Qalibah formation.

  13. Landslide stability: Role of rainfall-induced, laterally propagating, pore-pressure waves

    USGS Publications Warehouse

    Priest, G.R.; Schulz, W.H.; Ellis, W.L.; Allan, J.A.; Niem, A.R.; Niem, W.A.

    2011-01-01

    The Johnson Creek Landslide is a translational slide in seaward-dipping Miocene siltstone and sandstone (Astoria Formation) and an overlying Quaternary marine terrace deposit. The basal slide plane slopes sub-parallel to the dip of the Miocene rocks, except beneath the back-tilted toe block, where it slopes inland. Rainfall events raise pore-water pressure in the basal shear zone in the form of pulses of water pressure traveling laterally from the headwall graben down the axis of the slide at rates of 1-6 m/hr. Infiltration of meteoric water and vertical pressure transmission through the unsaturated zone has been measured at ~50 mm/hr. Infiltration and vertical pressure transmission were too slow to directly raise head at the basal shear zone prior to landslide movement. Only at the headwall graben was the saturated zone shallow enough for rainfall events to trigger lateral pulses of water pressure through the saturated zone. When pressure levels in the basal shear zone exceeded thresholds defined in this paper, the slide began slow, creeping movement as an intact block. As pressures exceeded thresholds for movement in more of the slide mass, movement accelerated, and differential displacement between internal slide blocks became more pronounced. Rainfall-induced pore-pressure waves are probably a common landslide trigger wherever effective hydraulic conductivity is high and the saturated zone is located near the surface in some part of a slide. An ancillary finding is apparently greater accuracy of grouted piezometers relative to those in sand packs for measurement of pore pressures at the installed depth.

  14. Effect of Processing Pressure on Isolated Pore Formation during Controlled Directional Solidification in Small Channels

    NASA Technical Reports Server (NTRS)

    Cox, Matthew C.; Anilkumar, Amrutur V.; Grugel, RIchard N.; Lee, Chun P.

    2008-01-01

    Directional solidification experiments were performed, using succinonitrile saturated with nitrogen gas, to examine the effects of in-situ processing pressure changes on the formation growth, and evolution of an isolated, cylindrical gaseous pore. A novel solidification facility, capable of processing thin cylindrical samples (I.D. < 1.0 mm), under controlled pressure conditions, was used for the experiments. A new experimental method for growing the isolated pore from a seed bubble is introduced. The experimental results indicate that an in-situ processing pressure change will result in either a transient change in pore diameter or a complete termination of pore growth, indicating that pressure changes can be used as a control parameter to terminate bubble growth. A simple analytical model has been introduced to explain the experimental observations.

  15. The change in orientation of subsidiary shears near faults containing pore fluid under high pressure

    USGS Publications Warehouse

    Byerlee, J.

    1992-01-01

    Byerlee, J., 1992. The change in orientation of subsidiary shears near faults containing pore fluid under high pressure. In: T. Mikumo, K. Aki, M. Ohnaka, L.J. Ruff and P.K.P. Spudich (Editors), Earthquake Source Physics and Earthquake Precursors. Tectonophysics, 211: 295-303. The mechanical effects of a fault containing near-lithostatic fluid pressure in which fluid pressure decreases monotonically from the core of the fault zone to the adjacent country rock is considered. This fluid pressure distribution has mechanical implications for the orientation of subsidiary shears around a fault. Analysis shows that the maximum principal stress is oriented at a high angle to the fault in the country rock where the pore pressure is hydrostatic, and rotates to 45?? to the fault within the fault zone where the pore pressure is much higher. This analysis suggests that on the San Andreas fault, where heat flow constraints require that the coefficient of friction for slip on the fault be less than 0.1, the pore fluid pressure on the main fault is 85% of the lithostatic pressure. The observed geometry of the subsidiary shears in the creeping section of the San Andreas are broadly consistent with this model, with differences that may be due to the heterogeneous nature of the fault. ?? 1992.

  16. Pore-pressure sensitivities to dynamic strains: observations in active tectonic regions

    USGS Publications Warehouse

    Barbour, Andrew J.

    2015-01-01

    Triggered seismicity arising from dynamic stresses is often explained by the Mohr-Coulomb failure criterion, where elevated pore pressures reduce the effective strength of faults in fluid-saturated rock. The seismic response of a fluid-rock system naturally depends on its hydro-mechanical properties, but accurately assessing how pore-fluid pressure responds to applied stress over large scales in situ remains a challenging task; hence, spatial variations in response are not well understood, especially around active faults. Here I analyze previously unutilized records of dynamic strain and pore-pressure from regional and teleseismic earthquakes at Plate Boundary Observatory (PBO) stations from 2006 through 2012 to investigate variations in response along the Pacific/North American tectonic plate boundary. I find robust scaling-response coefficients between excess pore pressure and dynamic strain at each station that are spatially correlated: around the San Andreas and San Jacinto fault systems, the response is lowest in regions of the crust undergoing the highest rates of secular shear strain. PBO stations in the Parkfield instrument cluster are at comparable distances to the San Andreas fault (SAF), and spatial variations there follow patterns in dextral creep rates along the fault, with the highest response in the actively creeping section, which is consistent with a narrowing zone of strain accumulation seen in geodetic velocity profiles. At stations in the San Juan Bautista (SJB) and Anza instrument clusters, the response depends non-linearly on the inverse fault-perpendicular distance, with the response decreasing towards the fault; the SJB cluster is at the northern transition from creeping-to-locked behavior along the SAF, where creep rates are at moderate to low levels, and the Anza cluster is around the San Jacinto fault, where to date there have been no statistically significant creep rates observed at the surface. These results suggest that the strength

  17. One-dimensional pore pressure diffusion of different grain-fluid mixtures

    NASA Astrophysics Data System (ADS)

    von der Thannen, Magdalena; Kaitna, Roland

    2015-04-01

    During the release and the flow of fully saturated debris, non-hydrostatic fluid pressure can build up and probably dissipate during the event. This excess fluid pressure has a strong influence on the flow and deposition behaviour of debris flows. Therefore, we investigate the influence of mixture composition on the dissipation of non-hydrostatic fluid pressures. For this we use a cylindrical pipe of acrylic glass with installed pore water pressure sensors in different heights and measure the evolution of the pore water pressure over time. Several mixtures with variable content of fine sediment (silt and clay) and variable content of coarse sediment (with fixed relative fractions of grains between 2 and 32 mm) are tested. For the fines two types of clay (smectite and kaolinite) and loam (Stoober Lehm) are used. The analysis is based on the one-dimensional consolidation theory which uses a diffusion coefficient D to model the decay of excess fluid pressure over time. Starting from artificially induced super-hydrostatic fluid pressures, we find dissipation coefficients ranging from 10-5 m²/s for liquid mixtures to 10-8 m²/s for viscous mixtures. The results for kaolinite and smectite are quite similar. For our limited number of mixtures the effect of fines content is more pronounced than the effect of different amounts of coarse particles.

  18. Pore closure in zeolitic imidazolate frameworks under mechanical pressure.

    PubMed

    Henke, Sebastian; Wharmby, Michael T; Kieslich, Gregor; Hante, Inke; Schneemann, Andreas; Wu, Yue; Daisenberger, Dominik; Cheetham, Anthony K

    2018-02-14

    We investigate the pressure-dependent mechanical behaviour of the zeolitic imidazolate framework ZIF-4 (M(im) 2 ; M 2+ = Co 2+ or Zn 2+ , im - = imidazolate) with high pressure, synchrotron powder X-ray diffraction and mercury intrusion measurements. A displacive phase transition from a highly compressible open pore ( op ) phase with continuous porosity (space group Pbca , bulk modulus ∼1.4 GPa) to a closed pore ( cp ) phase with inaccessible porosity (space group P 2 1 / c , bulk modulus ∼3.3-4.9 GPa) is triggered by the application of mechanical pressure. Over the course of the transitions, both ZIF-4 materials contract by about 20% in volume. However, the threshold pressure, the reversibility and the immediate repeatability of the phase transition depend on the metal cation. ZIF-4(Zn) undergoes the op-cp phase transition at a hydrostatic mechanical pressure of only 28 MPa, while ZIF-4(Co) requires about 50 MPa to initiate the transition. Interestingly, ZIF-4(Co) fully returns to the op phase after decompression, whereas ZIF-4(Zn) remains in the cp phase after pressure release and requires subsequent heating to switch back to the op phase. These variations in high pressure behaviour can be rationalised on the basis of the different electron configurations of the respective M 2+ ions (3d 10 for Zn 2+ and 3d 7 for Co 2+ ). Our results present the first examples of op-cp phase transitions ( i.e. breathing transitions) of ZIFs driven by mechanical pressure and suggest potential applications of these functional materials as shock absorbers, nanodampers, or in mechanocalorics.

  19. Discussion of pore pressure transmission under rain infiltration in a soil layer

    NASA Astrophysics Data System (ADS)

    Yang, S. Y.; Jan, C. D.

    2017-12-01

    The vadose zone (or unsaturated zone) denotes the geologic media between ground surface and the water table in situ where the openings, or pores, in the soil (rock) layers are partially filled with water and air. In this landscape, rainwater infiltrates into soils advancing through this vadose zone and could generates a shallow saturation zone at soil bedrock boundary due to permeability contrast. This saturation zone leads to downslope shallow subsurface storm runoff that contributes to a part of saturation overland flow, dominating water reaching river channels. Hence, unsaturated processes (e.g., rain infiltration) is an important issue that can determine the timing and magnitude of positive pore pressure and discharge peaks, and the characteristics of runoff, water chemistry, hillslope stability is also tie to the processes. In this study, we investigated the transmission of pore pressure evolution in the vadose zone for diverse soil materials based on poroelasticity theory. Commonly, a traditional way is to utilize the Richard's equation to predict pore pressure evolution under unsaturated rain infiltration, ignoring the inertial effect on the process. Here we relax this limitation and propose two reference time tk and tep that can represent the arriving time at a certain depth of wave propagation and dissipation, respectively. Form ground surface to a depth of 1 m, tk has significant differences under nearly unsaturated conditions for diverse soil properties; however, no evident variations in tk can be observed under nearly saturated conditions. Values of tep for loose, cohesionless soils are much greater but decreases to the smallest one (within 1 day) than those for other soil properties under a nearly saturated condition. Results indicate that transient pore pressure transmission is mainly dominated by dynamic wave propagation but the effect of dissipation could become more important with increase in water saturation.

  20. In situ pore-pressure evolution during dynamic CPT measurements in soft sediments of the western Baltic Sea

    NASA Astrophysics Data System (ADS)

    Seifert, Annedore; Stegmann, Sylvia; Mörz, Tobias; Lange, Matthias; Wever, Thomas; Kopf, Achim

    2008-08-01

    We present in situ strength and pore-pressure measurements from 57 dynamic cone penetration tests in sediments of Mecklenburg ( n = 51), Eckernförde ( n = 2) and Gelting ( n = 4) bays, western Baltic Sea, characterised by thick mud layers and partially free microbial gas resulting from the degradation of organic material. In Mecklenburg and Eckernförde bays, sediment sampling by nine gravity cores served sedimentological characterisation, analyses of geotechnical properties, and laboratory shear tests. At selected localities, high-resolution echo-sounder profiles were acquired. Our aim was to deploy a dynamic cone penetrometer (CPT) to infer sediment shear strength and cohesion of the sea bottom as a function of fluid saturation. The results show very variable changes in pore pressure and sediment strength during the CPT deployments. The majority of the CPT measurements ( n = 54) show initially negative pore-pressure values during penetration, and a delayed response towards positive pressures thereafter. This so-called type B pore-pressure signal was recorded in all three bays, and is typically found in soft muds with high water contents and undrained shear strengths of 1.6-6.4 kPa. The type B signal is further affected by displacement of sediment and fluid upon penetration of the lance, skin effects during dynamic profiling, enhanced consolidation and strength of individual horizons, the presence of free gas, and a dilatory response of the sediment. In Mecklenburg Bay, the remaining small number of CPT measurements ( n = 3) show a well-defined peak in both pore pressure and cone resistance during penetration, i.e. an initial marked increase which is followed by exponential pore-pressure decay during dissipation. This so-called type A pore-pressure signal is associated with normally consolidated mud, with indurated clay layers showing significantly higher undrained shear strength (up to 19 kPa). In Eckernförde and Gelting bays pore-pressure response type B is

  1. Constraints on Pore Pressure in Subduction Zones From Geotechnical Tests and Physical Properties Data

    NASA Astrophysics Data System (ADS)

    Saffer, D. M.; McKiernan, A. W.

    2005-12-01

    At subduction zones, as incoming sediments are either offscraped or underthrust at the trench, elevated pore pressures result from the combination of rapid loading and low permeability. Pore pressure within underthrust sediment is especially important for the mechanical strength of the plate boundary fault system, because the main décollement localizes immediately above this sediment, and at many subduction zones steps downward into it. Because the underthrust sediment undergoes progressive uniaxial (vertical) strain, quantitative estimates of in situ pore pressure can be obtained by several methods, including: (1) maximum past burial stress ( Pv'}) from laboratory consolidation tests on core samples, and (2) observed compaction trends in boreholes. These methods allow a detailed view of pore pressure and its variability down-section, providing insight into dewatering processes and the evolution of shear strength relevant to early development of the décollement. Geotechnical tests also provide independent measurement of the coefficient of consolidation ( Cv), compressibility ( mv), and permeability (k) of sediment samples, which can be used to parameterize forward models of pressure generation. Here, I discuss pore pressure estimates derived from (1) consolidation tests on core samples, and (2) observed porosity profiles, along transects where ODP drilling has sampled sediment at the Nankai, N. Barbados, and Costa Rican subduction zones. At all three margins, the two independent methods yield consistent results, and indicate development of significant overpressures that increase systematically with distance from the trench. The values are in good agreement with direct measurements in 2 instrumented boreholes at Barbados, maximum and minimum bounds from the known loading rate, and results of 2-D numerical models of fluid flow. Inferred pressures document nearly undrained conditions at the base of the section (excess pressures equal to the load emplaced by

  2. Reservoir transport and poroelastic properties from oscillating pore pressure experiments

    NASA Astrophysics Data System (ADS)

    Hasanov, Azar K.

    Hydraulic transport properties of reservoir rocks, permeability and storage capacity are traditionally defined as rock properties, responsible for the passage of fluids through the porous rock sample, as well as their storage. The evaluation of both is an important part of any reservoir characterization workflow. Moreover, permeability and storage capacity are main inputs into any reservoir simulation study, routinely performed by reservoir engineers on almost any major oil and gas field in the world. An accurate reservoir simulation is essential for production forecast and economic analysis, hence the transport properties directly control the profitability of the petroleum reservoir and their estimation is vital for oil and gas industry. This thesis is devoted to an integrated study of reservoir rocks' hydraulic, streaming potential and poroelastic properties as measured with the oscillating pore pressure experiment. The oscillating pore pressure method is traditionally used to measure hydraulic transport properties. We modified the method and built an experimental setup, capable of measuring all aforementioned rock properties simultaneously. The measurements were carried out for four conventional reservoir-rock quality samples at a range of oscillation frequencies and effective stresses. An apparent frequency dependence of permeability and streaming potential coupling coefficient was observed. Measured frequency dispersion of drained poroelastic properties indicates an intrinsically inelastic nature of the porous mineral rock frame. Standard Linear Model demonstrated the best fit to the experimental dispersion data. Pore collapse and grain crushing effects took place during hydrostatic loading of the dolomitic sample and were observed in permeability, coupling coefficient and poroelastic measurements simultaneously. I established that hydraulically-measured storage capacities are overestimated by almost one order of magnitude when compared to elastically

  3. Optimization of a high-pressure pore water extraction device.

    PubMed

    Cyr, Martin; Daidié, Alain

    2007-02-01

    High-pressure squeezing is a technique used for the extraction of the pore water of porous materials such as sediments, soils, rocks, and concrete. The efficiency of extraction depends on the maximum pressures on the materials. This article presents the design of a high-pressure device reaching an axial pressure of 1000 MPa which has been developed to improve the efficiency of extraction. The increase in squeezing pressure implies high stresses inside the chamber, so specialized expertise was required to design a safe, functional device that could withstand pressures significantly higher than common laboratory equipment. The design includes finite element calculations, selection of appropriate materials, and descriptive construction details for the apparatus. It also includes an experimental study of the performance of the apparatus in terms of extraction efficiency.

  4. A variable pressure method for characterizing nanoparticle surface charge using pore sensors.

    PubMed

    Vogel, Robert; Anderson, Will; Eldridge, James; Glossop, Ben; Willmott, Geoff

    2012-04-03

    A novel method using resistive pulse sensors for electrokinetic surface charge measurements of nanoparticles is presented. This method involves recording the particle blockade rate while the pressure applied across a pore sensor is varied. This applied pressure acts in a direction which opposes transport due to the combination of electro-osmosis, electrophoresis, and inherent pressure. The blockade rate reaches a minimum when the velocity of nanoparticles in the vicinity of the pore approaches zero, and the forces on typical nanoparticles are in equilibrium. The pressure applied at this minimum rate can be used to calculate the zeta potential of the nanoparticles. The efficacy of this variable pressure method was demonstrated for a range of carboxylated 200 nm polystyrene nanoparticles with different surface charge densities. Results were of the same order as phase analysis light scattering (PALS) measurements. Unlike PALS results, the sequence of increasing zeta potential for different particle types agreed with conductometric titration.

  5. High-velocity frictional experiments on dolerite and quartzite under controlled pore pressure

    NASA Astrophysics Data System (ADS)

    Togo, T.; Shimamoto, T.; Ma, S.

    2013-12-01

    High-velocity friction experiments on rocks with or without gouge have been conducted mostly under dry conditions and demonstrated dramatic weakening of faults at high velocities (e.g., Di Toro et al., 2011, Nature). Recent experiments under wet conditions (e.g., Ujiie and Tsutsumi, 2010, GRL; Faulkner et al., 2011, GRL) revealed very different behaviors from those of dry faults, but those experiments were done under drained conditions. Experiments with controlled pore pressure Pp are definitely needed to determine mechanical properties of faults under fluid-rich environments such as those in subduction zones. Thus we have developed a pressure vessel that can be attached to our rotary-shear low to high-velocity friction apparatus (Marui Co Ltd., MIS-233-1-76). With a current specimen holder, friction experiments can be done on hollow-cylindrical specimens of 15 and 40 mm in inner and outer diameters, respectively, at controlled Pp to 35 MPa, at effective normal stresses of 3~9 MPa, and at slip rates of 60 mm/year to 2 m/s. An effective normal stress can be applied with a 100 kN hydraulic actuator. We report an outline of the experimental system and preliminary high-velocity experiments on Shanxi dolerite and a quartzite from China that are composed of pyroxene and plagioclase and of almost pure quartz, respectively. High-velocity friction experiments were performed on hollow-cylindrical specimens of Shanxi dolerite at effective normal stresses of 0.13~1.07 MPa and at slip rates of 1, 10, 100 and 1000 mm/sec. All experiments were conducted first with the nitrogen gas filling the pressure vessel (dry tests) and then with a controlled pore-water pressure (wet tests). In the dry tests an axial force was kept at 1 kN and the nitrogen gas pressure was increased in steps to 5 MPa to change an effective normal stress. In the wet tests the specimens were soaked in distilled water in the vessel and Pp was applied by nitrogen gas in a similar manner as in the dry tests

  6. Characterization of pore structure in cement-based materials using pressurization-depressurization cycling mercury intrusion porosimetry (PDC-MIP)

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Zhou Jian, E-mail: Jian.Zhou@tudelft.n; Ye Guang, E-mail: g.ye@tudelft.n; Magnel Laboratory for Concrete Research, Department of Structural Engineering, Ghent University, Technologiepark-Zwijnaarde 904 B-9052, Ghent

    2010-07-15

    Numerous mercury intrusion porosimetry (MIP) studies have been carried out to investigate the pore structure in cement-based materials. However, the standard MIP often results in an underestimation of large pores and an overestimation of small pores because of its intrinsic limitation. In this paper, an innovative MIP method is developed in order to provide a more accurate estimation of pore size distribution. The new MIP measurements are conducted following a unique mercury intrusion procedure, in which the applied pressure is increased from the minimum to the maximum by repeating pressurization-depressurization cycles instead of a continuous pressurization followed by a continuousmore » depressurization. Accordingly, this method is called pressurization-depressurization cycling MIP (PDC-MIP). By following the PDC-MIP testing sequence, the volumes of the throat pores and the corresponding ink-bottle pores can be determined at every pore size. These values are used to calculate pore size distribution by using the newly developed analysis method. This paper presents an application of PDC-MIP on the investigation of the pore size distribution in cement-based materials. The experimental results of PDC-MIP are compared with those measured by standard MIP. The PDC-MIP is further validated with the other experimental methods and numerical tool, including nitrogen sorption, backscanning electron (BSE) image analysis, Wood's metal intrusion porosimetry (WMIP) and the numerical simulation by the cement hydration model HYMOSTRUC3D.« less

  7. Fluid displacement fronts in porous media: pore scale interfacial jumps, pressure bursts and acoustic emissions

    NASA Astrophysics Data System (ADS)

    Moebius, Franziska; Or, Dani

    2014-05-01

    The macroscopically smooth and regular motion of fluid fronts in porous media is composed of numerous rapid pore-scale interfacial jumps and pressure bursts that involve intense interfacial energy release in the form of acoustic emissions. The characteristics of these pore scale events affect residual phase entrapment and transport properties behind the front. We present experimental studies using acoustic emission technique (AE), rapid imaging, and liquid pressure measurements to characterize these processes during drainage and imbibition in simple porous media. Imbibition and drainage produce different AE signatures (AE amplitudes obey a power law). For rapid drainage, AE signals persist long after cessation of front motion reflecting fluid redistribution and interfacial relaxation. Imaging revealed that the velocity of interfacial jumps often exceeds front velocity by more than 50 fold and is highly inertial component (Re>1000). Pore invasion volumes reduced deduced from pressure fluctuations waiting times (for constant withdrawal rates) show remarkable agreement with geometrically-deduced pore volumes. Discrepancies between invaded volumes and geometrical pores increase with increasing capillary numbers due to constraints on evacuation opportunity times and simultaneous invasion events. A mechanistic model for interfacial motions in a pore-throat network was developed to investigate interfacial dynamics focusing on the role of inertia. Results suggest that while pore scale dynamics were sensitive to variations in pore geometry and boundary conditions, inertia exerted only a minor effect on phase entrapment. The study on pore scale invasion events paints a complex picture of rapid and inertial motions and provides new insights on mechanisms at displacement fronts that are essential for improved macroscopic description of multiphase flows in porous media.

  8. An evaluation of factors influencing pore pressure in accretionary complexes: Implications for taper angle and wedge mechanics

    USGS Publications Warehouse

    Saffer, D.M.; Bekins, B.A.

    2006-01-01

    At many subduction zones, accretionary complexes form as sediment is off-scraped from the subducting plate. Mechanical models that treat accretionary complexes as critically tapered wedges of sediment demonstrate that pore pressure controls their taper angle by modifying basal and internal shear strength. Here, we combine a numerical model of groundwater flow with critical taper theory to quantify the effects of sediment and de??collement permeability, sediment thickness, sediment partitioning between accretion and underthrusting, and plate convergence rate on steady state pore pressure. Our results show that pore pressure in accretionary wedges can be viewed as a dynamically maintained response to factors which drive pore pressure (source terms) and those that limit flow (permeability and drainage path length). We find that sediment permeability and incoming sediment thickness are the most important factors, whereas fault permeability and the partitioning of sediment have a small effect. For our base case model scenario, as sediment permeability is increased, pore pressure decreases from near-lithostatic to hydrostatic values and allows stable taper angles to increase from ??? 2.5?? to 8??-12.5??. With increased sediment thickness in our models (from 100 to 8000 m), increased pore pressure drives a decrease in stable taper angle from 8.4??-12.5?? to 15?? to <4??) with increased sediment thickness (from <1 to 7 km). One key implication is that hydrologic properties may strongly influence the strength of the crust in a wide range of geologic settings. Copyright 2006 by the American Geophysical Union.

  9. Effects of high shock pressures and pore morphology on hot spot mechanisms in HMX

    NASA Astrophysics Data System (ADS)

    Springer, H. K.; Tarver, C. M.; Bastea, S.

    2017-01-01

    The shock initiation and detonation behavior of heterogeneous solid explosives is governed by its microstructure and reactive properties. New additive manufacturing techniques offer unprecedented control of explosive microstructures previously impossible, enabling us to develop novel explosives with tailored shock sensitivity and detonation properties. Since microstructure-performance relationships are not well established for explosives, there is little material design guidance for these manufacturing techniques. In this study, we explore the effects of high shock pressures (15-38 GPa) with long shock durations and different pore morphologies on hot spot mechanisms in HMX. HMX is chosen as the model material because we have experimental data on many of the chemical-thermal-mechanical properties required for pore collapse simulations. Our simulations are performed using the multi-physics arbitrary Lagrangian Eulerian finite element hydrocode, ALE3D, with Cheetah-based models for the unreacted and the product equation-of-states. We use a temperature-dependent specific heat with the unreacted equation-of-state and a temperature-dependent viscosity model to ensure accurate shock temperatures for subsequent chemistry. The Lindemann Law model is used for shock melting in HMX. In contrast to previous pore collapse studies at lower shock pressures (≤10 GPa) in HMX and shorter post-collapse burning times, our calculations show that shock melting occurs above 15 GPa due to higher bulk heating and a prominent elongated ("jet-like") hot spot region forms at later times. The combination of the elongated, post-collapse hot spot region and the higher bulk heating with increasing pressure dramatically increases the growth rate of reaction. Our calculations show that the reaction rate, dF/dt, increases with increasing shock pressure. We decompose the reaction rate into ignition ((dF/dt)ig) and growth ((dF/dt)gr) phases to better analyze our results. We define the ignition phase

  10. Deterministic estimate of hypocentral pore fluid pressure of the M5.8 Pawnee, Oklahoma earthquake: Lower pre-injection pressure requires lower resultant pressure for slip

    NASA Astrophysics Data System (ADS)

    Levandowski, W. B.; Walsh, F. R. R.; Yeck, W.

    2016-12-01

    Quantifying the increase in pore-fluid pressure necessary to cause slip on specific fault planes can provide actionable information for stakeholders to potentially mitigate hazard. Although the M5.8 Pawnee earthquake occurred on a previously unmapped fault, we can retrospectively estimate the pore-pressure perturbation responsible for this event. We first estimate the normalized local stress tensor by inverting focal mechanisms surrounding the Pawnee Fault. Faults are generally well oriented for slip, with instabilities averaging 96% of maximum. Next, with an estimate of the weight of local overburden we solve for the pore pressure needed at the hypocenters. Specific to the Pawnee fault, we find that hypocentral pressure 43-104% of hydrostatic (accounting for uncertainties in all relevant parameters) would have been sufficient to cause slip. The dominant source of uncertainty is the pressure on the fault prior to fluid injection. Importantly, we find that lower pre-injection pressure requires lower resultant pressure to cause slip, decreasing from a regional average of 30% above hydrostatic pressure if the hypocenters begin at hydrostatic pressure to 6% above hydrostatic pressure with no pre-injection fluid. This finding suggests that underpressured regions such as northern Oklahoma are predisposed to injection-induced earthquakes. Although retrospective and forensic, similar analyses of other potentially induced events and comparisons to natural earthquakes will provide insight into the relative importance of fault orientation, the magnitude of the local stress field, and fluid-pressure migration in intraplate seismicity.

  11. Observations of wave-induced pore pressure gradients and bed level response on a surf zone sandbar

    NASA Astrophysics Data System (ADS)

    Anderson, Dylan; Cox, Dan; Mieras, Ryan; Puleo, Jack A.; Hsu, Tian-Jian

    2017-06-01

    Horizontal and vertical pressure gradients may be important physical mechanisms contributing to onshore sediment transport beneath steep, near-breaking waves in the surf zone. A barred beach was constructed in a large-scale laboratory wave flume with a fixed profile containing a mobile sediment layer on the crest of the sandbar. Horizontal and vertical pore pressure gradients were obtained by finite differences of measurements from an array of pressure transducers buried within the upper several centimeters of the bed. Colocated observations of erosion depth were made during asymmetric wave trials with wave heights between 0.10 and 0.98 m, consistently resulting in onshore sheet flow sediment transport. The pore pressure gradient vector within the bed exhibited temporal rotations during each wave cycle, directed predominantly upward under the trough and then rapidly rotating onshore and downward as the wavefront passed. The magnitude of the pore pressure gradient during each phase of rotation was correlated with local wave steepness and relative depth. Momentary bed failures as deep as 20 grain diameters were coincident with sharp increases in the onshore-directed pore pressure gradients, but occurred at horizontal pressure gradients less than theoretical critical values for initiation of the motion for compact beds. An expression combining the effects of both horizontal and vertical pore pressure gradients with bed shear stress and soil stability is used to determine that failure of the bed is initiated at nonnegligible values of both forces.Plain Language SummaryThe <span class="hlt">pressure</span> gradient present within the seabed beneath breaking waves may be an important physical mechanism transporting sediment. A large-scale laboratory was used to replicate realistic surfzone conditions in controlled tests, allowing for horizontal and vertical <span class="hlt">pressure</span> gradient magnitudes and the resulting sediment bed response to be observed with</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/pages/biblio/1430898-heterogeneity-pore-pressure-injectate-chemistry-control-measures-geologic-carbon-storage','SCIGOV-DOEP'); return false;" href="https://www.osti.gov/pages/biblio/1430898-heterogeneity-pore-pressure-injectate-chemistry-control-measures-geologic-carbon-storage"><span>Heterogeneity, <span class="hlt">pore</span> <span class="hlt">pressure</span>, and injectate chemistry: Control measures for geologic carbon storage</span></a></p> <p><a target="_blank" href="http://www.osti.gov/pages">DOE PAGES</a></p> <p>Dewers, Thomas; Eichhubl, Peter; Ganis, Ben; ...</p> <p>2017-11-28</p> <p>Desirable outcomes for geologic carbon storage include maximizing storage efficiency, preserving injectivity, and avoiding unwanted consequences such as caprock or wellbore leakage or induced seismicity during and post injection. Here, to achieve these outcomes, three control measures are evident including <span class="hlt">pore</span> <span class="hlt">pressure</span>, injectate chemistry, and knowledge and prudent use of geologic heterogeneity. Field, experimental, and modeling examples are presented that demonstrate controllable GCS via these three measures. Observed changes in reservoir response accompanying CO 2 injection at the Cranfield (Mississippi, USA) site, along with lab testing, show potential for use of injectate chemistry as a means to alter fracture permeabilitymore » (with concomitant improvements for sweep and storage efficiency). Further control of reservoir sweep attends brine extraction from reservoirs, with benefit for <span class="hlt">pressure</span> control, mitigation of reservoir and wellbore damage, and water use. State-of-the-art validated models predict the extent of damage and deformation associated with <span class="hlt">pore</span> <span class="hlt">pressure</span> hazards in reservoirs, timing and location of networks of fractures, and development of localized leakage pathways. Experimentally validated geomechanics models show where wellbore failure is likely to occur during injection, and efficiency of repair methods. Use of heterogeneity as a control measure includes where best to inject, and where to avoid attempts at storage. Lastly, an example is use of waste zones or leaky seals to both reduce <span class="hlt">pore</span> <span class="hlt">pressure</span> hazards and enhance residual CO 2 trapping.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/biblio/1430898-heterogeneity-pore-pressure-injectate-chemistry-control-measures-geologic-carbon-storage','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/1430898-heterogeneity-pore-pressure-injectate-chemistry-control-measures-geologic-carbon-storage"><span>Heterogeneity, <span class="hlt">pore</span> <span class="hlt">pressure</span>, and injectate chemistry: Control measures for geologic carbon storage</span></a></p> <p><a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a></p> <p>Dewers, Thomas; Eichhubl, Peter; Ganis, Ben</p> <p></p> <p>Desirable outcomes for geologic carbon storage include maximizing storage efficiency, preserving injectivity, and avoiding unwanted consequences such as caprock or wellbore leakage or induced seismicity during and post injection. Here, to achieve these outcomes, three control measures are evident including <span class="hlt">pore</span> <span class="hlt">pressure</span>, injectate chemistry, and knowledge and prudent use of geologic heterogeneity. Field, experimental, and modeling examples are presented that demonstrate controllable GCS via these three measures. Observed changes in reservoir response accompanying CO 2 injection at the Cranfield (Mississippi, USA) site, along with lab testing, show potential for use of injectate chemistry as a means to alter fracture permeabilitymore » (with concomitant improvements for sweep and storage efficiency). Further control of reservoir sweep attends brine extraction from reservoirs, with benefit for <span class="hlt">pressure</span> control, mitigation of reservoir and wellbore damage, and water use. State-of-the-art validated models predict the extent of damage and deformation associated with <span class="hlt">pore</span> <span class="hlt">pressure</span> hazards in reservoirs, timing and location of networks of fractures, and development of localized leakage pathways. Experimentally validated geomechanics models show where wellbore failure is likely to occur during injection, and efficiency of repair methods. Use of heterogeneity as a control measure includes where best to inject, and where to avoid attempts at storage. Lastly, an example is use of waste zones or leaky seals to both reduce <span class="hlt">pore</span> <span class="hlt">pressure</span> hazards and enhance residual CO 2 trapping.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2009JGRB..114.7401S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2009JGRB..114.7401S"><span><span class="hlt">Pore</span> <span class="hlt">pressure</span> development beneath the décollement at the Nankai subduction zone: Implications for plate boundary fault strength and sediment dewatering</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Skarbek, Robert M.; Saffer, Demian M.</p> <p>2009-07-01</p> <p>Despite its importance for plate boundary fault processes, quantitative constraints on <span class="hlt">pore</span> <span class="hlt">pressure</span> are rare, especially within fault zones. Here, we combine laboratory permeability measurements from core samples with a model of loading and <span class="hlt">pore</span> <span class="hlt">pressure</span> diffusion to investigate <span class="hlt">pore</span> fluid <span class="hlt">pressure</span> evolution within underthrust sediment at the Nankai subduction zone. Independent estimates of <span class="hlt">pore</span> <span class="hlt">pressure</span> to ˜20 km from the trench, combined with permeability measurements conducted over a wide range of effective stresses and porosities, allow us to reliably simulate <span class="hlt">pore</span> <span class="hlt">pressure</span> development to greater depths than in previous studies and to directly quantify <span class="hlt">pore</span> <span class="hlt">pressure</span> within the plate boundary fault zone itself, which acts as the upper boundary of the underthrusting section. Our results suggest that the time-averaged excess <span class="hlt">pore</span> <span class="hlt">pressure</span> (P*) along the décollement ranges from 1.7-2.1 MPa at the trench to 30.2-35.9 MPa by 40 km landward, corresponding to <span class="hlt">pore</span> <span class="hlt">pressure</span> ratios of λb = 0.68-0.77. For friction coefficients of 0.30-0.40, the resulting shear strength along the décollement remains <12 MPa over this region. When noncohesive critical taper theory is applied using these values, the required <span class="hlt">pore</span> <span class="hlt">pressure</span> ratios within the wedge are near hydrostatic (λw = 0.41-0.59), implying either that <span class="hlt">pore</span> <span class="hlt">pressure</span> throughout the wedge is low or that the fault slips only during transient pulses of elevated <span class="hlt">pore</span> <span class="hlt">pressure</span>. In addition, simulated downward migration of minima in effective stress during drainage provides a quantitative explanation for down stepping of the décollement that is consistent with observations at Nankai.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/biblio/6728510-abnormal-pressure-study-malay-penyu-basins-regional-understanding','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/6728510-abnormal-pressure-study-malay-penyu-basins-regional-understanding"><span><span class="hlt">Abnormal</span> <span class="hlt">pressure</span> study in the Malay and Penyu Basins: A regional understanding</span></a></p> <p><a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a></p> <p>Kader, M.S.; Leslie, W.</p> <p>1994-07-01</p> <p>A majority of wells drilled in the Malay and Penyu basins were terminated due to <span class="hlt">abnormal</span> <span class="hlt">pressure</span>. Blowouts and the subsequent loss of technical data have always been a concern during drilling operations. This study employs data from 94 exploratory wells spread throughout the Malay and Penyu basins. The postdrill <span class="hlt">abnormal</span> <span class="hlt">pressure</span> predictive method used is <span class="hlt">pressure</span> vs. depth plots of data obtained from Repeat Formation tester (RFT) readings. The study results indicate that <span class="hlt">abnormal</span> <span class="hlt">pressure</span> occurs in a progressively older stratigraphic unit toward the basin margins. The margins of the Malay and the entire Penyu basins tend to bemore » normally <span class="hlt">pressured</span>. The onset of <span class="hlt">abnormal</span> <span class="hlt">pressure</span> appears to be abrupt in the northern portion and more gradual in the southern part of the Malay Basin. <span class="hlt">Abnormal</span> <span class="hlt">pressure</span> in the Malay Basin is found to be neither depth dependent nor age related. Many factors can cause the <span class="hlt">abnormal</span> formation <span class="hlt">pressures</span>. In some areas, a combination of factors prevails. Rapid deposition of the middle to late Miocene siliciclastic sediments appears to be a dominant cause particularly in the center of the Malay Basin. A low sand:shale ratio coupled with a high geothermal gradient is also found to be a local cause near the axis of the basin. This phenomenon is crucial to the understanding of hydrocarbon migration and will enable the planning of safe and efficient drilling campaigns.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018MMI....24..549K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018MMI....24..549K"><span>Effect of Time-Dependent Pinning <span class="hlt">Pressure</span> on <span class="hlt">Abnormal</span> Grain Growth: Phase Field Simulation</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kim, Jeong Min; Min, Guensik; Shim, Jae-Hyeok; Lee, Kyung Jong</p> <p>2018-05-01</p> <p>The effect of the time-dependent pinning <span class="hlt">pressure</span> of precipitates on <span class="hlt">abnormal</span> grain growth has been investigated by multiphase field simulation with a simple precipitation model. The application of constant pinning <span class="hlt">pressure</span> is problematic because it always induces <span class="hlt">abnormal</span> grain growth or no grain growth, which is not reasonable considering the real situation. To produce time-dependent pinning <span class="hlt">pressure</span>, both precipitation kinetics and precipitate coarsening kinetics have been considered with two rates: slow and fast. The results show that <span class="hlt">abnormal</span> grain growth is suppressed at the slow precipitation rate. At the slow precipitation rate, the overall grain growth caused by the low pinning <span class="hlt">pressure</span> in the early stage indeed plays a role in preventing <span class="hlt">abnormal</span> grain growth by reducing the mobility advantage of <span class="hlt">abnormal</span> grains. In addition, the fast precipitate coarsening rate tends to more quickly transform <span class="hlt">abnormal</span> grain growth into normal grain growth by inducing the active growth of grains adjacent to the <span class="hlt">abnormal</span> grains in the early stage. Therefore, the present study demonstrates that the time dependence of the pinning <span class="hlt">pressure</span> of precipitates is a critical factor that determines the grain growth mode.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018MMI...tmp...51K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018MMI...tmp...51K"><span>Effect of Time-Dependent Pinning <span class="hlt">Pressure</span> on <span class="hlt">Abnormal</span> Grain Growth: Phase Field Simulation</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kim, Jeong Min; Min, Guensik; Shim, Jae-Hyeok; Lee, Kyung Jong</p> <p>2018-03-01</p> <p>The effect of the time-dependent pinning <span class="hlt">pressure</span> of precipitates on <span class="hlt">abnormal</span> grain growth has been investigated by multiphase field simulation with a simple precipitation model. The application of constant pinning <span class="hlt">pressure</span> is problematic because it always induces <span class="hlt">abnormal</span> grain growth or no grain growth, which is not reasonable considering the real situation. To produce time-dependent pinning <span class="hlt">pressure</span>, both precipitation kinetics and precipitate coarsening kinetics have been considered with two rates: slow and fast. The results show that <span class="hlt">abnormal</span> grain growth is suppressed at the slow precipitation rate. At the slow precipitation rate, the overall grain growth caused by the low pinning <span class="hlt">pressure</span> in the early stage indeed plays a role in preventing <span class="hlt">abnormal</span> grain growth by reducing the mobility advantage of <span class="hlt">abnormal</span> grains. In addition, the fast precipitate coarsening rate tends to more quickly transform <span class="hlt">abnormal</span> grain growth into normal grain growth by inducing the active growth of grains adjacent to the <span class="hlt">abnormal</span> grains in the early stage. Therefore, the present study demonstrates that the time dependence of the pinning <span class="hlt">pressure</span> of precipitates is a critical factor that determines the grain growth mode.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016AGUFM.V53A3069A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016AGUFM.V53A3069A"><span>How <span class="hlt">Pore</span>-Fluid <span class="hlt">Pressure</span> due to Heavy Rainfall Influences Volcanic Eruptions, Example of 1998 and 2008 Eruptions of Cerro Azul (Galapagos)</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Albino, F.; Amelung, F.; Gregg, P. M.</p> <p>2016-12-01</p> <p>About 30 worldwide seismic studies have shown a strong correlation between rainfall and earthquakes in the past 22 years (e.g. Costain and Bollinger, 2010). Such correlation has been explained by the phenomenon of hydro-seismicity via <span class="hlt">pore</span> <span class="hlt">pressure</span> diffusion: an increase of <span class="hlt">pore</span>-fluid in the upper crust reduces the normal stress on faults, which can trigger shear failure. Although this <span class="hlt">pore</span> <span class="hlt">pressure</span> effect is widely known for earthquakes, this phenomenon and more broadly poro-elasticity process are not widely studied on volcanoes. However, we know from our previous works that tensile failures that open to propagate magma through the surface are also <span class="hlt">pore</span> <span class="hlt">pressure</span> dependent. We have demonstrated that an increase of <span class="hlt">pore</span> <span class="hlt">pressure</span> largely reduces the overpressure required to rupture the magma reservoir. We have shown that the <span class="hlt">pore</span> <span class="hlt">pressure</span> has more influence on reservoir stability than other parameters such as the reservoir depth or the edifice loading. Here, we investigate how small <span class="hlt">pore</span>-fluid changes due to hydrothermal or aquifer refill during heavy rainfall may perturb the conditions of failure around magma reservoirs and, what is more, if these perturbations are enough to trigger magma intrusions. We quantify the <span class="hlt">pore</span> <span class="hlt">pressure</span> effect on magmatic system by combining 1) 1D <span class="hlt">pore</span> <span class="hlt">pressure</span> diffusion model to quantify how <span class="hlt">pore</span> <span class="hlt">pressure</span> changes from surface to depth after heavy rainfall events and 2) 2D poro-elastic numerical model to provide the evolution of failure conditions of the reservoir as a consequence of these <span class="hlt">pore</span> <span class="hlt">pressure</span> changes. Sensitivity analysis is also performed to characterize the influence on our results of the poro-elastic parameters (hydraulic diffusivity, permeability and porosity) and the geometry of the magma reservoir and the aquifer (depth, size, shape). Finally, we apply our methodology to Cerro Azul volcano (Galapagos) where both last eruptions (1998 and 2008) occurred just after heavy rainfall events, without any pre-eruptive inflation. In</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015AGUFMMR33A2642N','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AGUFMMR33A2642N"><span>Dependencies of <span class="hlt">pore</span> <span class="hlt">pressure</span> on elastic wave velocities and Vp/Vs ratio for thermally cracked gabbro</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Nishimura, K.; Uehara, S. I.; Mizoguchi, K.</p> <p>2015-12-01</p> <p>Marine seismic refraction have found that there are high Vp/Vs ratio regions in oceanic crusts at subducting oceanic plates (e.g, Cascadia subduction zone (2.0-2.8) (Audet et al., 2009)). Previous studies based on laboratory measurements indicated that Vp/Vs ratio is high when porosity and/or <span class="hlt">pore</span> <span class="hlt">pressure</span> is high (Christensen, 1984; Peacock et al., 2011). Although several studies have investigated the relationships between fracture distributions and Vp, Vs (e.g., Wang et al., 2012; Blake et al., 2013), the relationships for rocks (e.g., gabbro and basalt) composing oceanic crust are still unclear. This study reports the results of laboratory measurements of Vp, Vs (transmission method) at controlled confining and <span class="hlt">pore</span> <span class="hlt">pressure</span> and estimation of Vp/Vs ratio for thermally cracked gabbro which mimic highly fractured rocks in the high Vp/Vs ratio zone, in order to declare the dependence of fracture distributions on Vp/Vs. For the measurements, we prepared three type specimens; a non-heated intact specimen, specimens heated up to 500 °C and 700 °C for 24 hours. Porosities of intact, 500 °C and 700 °C specimens measured under the atmospheric <span class="hlt">pressure</span> are 0.5, 3.4 and 3.5%, respectively. Measurements were conducted at a constant confining <span class="hlt">pressure</span> of 50 MPa, with decreasing <span class="hlt">pore</span> <span class="hlt">pressure</span> from 49 to 0.1 MPa and then increasing to 49 MPa. While Vp/Vs for the intact specimen is almost constant at elevated <span class="hlt">pore</span> <span class="hlt">pressure</span>, the Vp/Vs values for the thermally cracked ones were 2.0~2.2 when <span class="hlt">pore</span> <span class="hlt">pressure</span> was larger than 30 MPa. In future, we will reveal the relationship between the measured elastic wave velocities and the characteristics of the microfracture distribution. This work was supported by JSPS Grant-in-Aid for Scientific Research (Grant Number 26400492).</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015EGUGA..1715522D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015EGUGA..1715522D"><span>Permeability changes induced by microfissure closure and opening in tectonized materials. Effect on slope <span class="hlt">pore</span> <span class="hlt">pressure</span> regime.</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>De la Fuente, Maria; Vaunat, Jean; Pedone, Giuseppe; Cotecchia, Federica; Sollecito, Francesca; Casini, Francesca</p> <p>2015-04-01</p> <p>Tectonized clays are complex materials characterized by several levels of structures that may evolve during load and wetting/drying processes. Some microstructural patterns, as microfissures, have a particular influence on the value of permeability which is one of the main factors controlling <span class="hlt">pore</span> <span class="hlt">pressure</span> regime in slopes. In this work, the <span class="hlt">pore</span> <span class="hlt">pressure</span> regime measured in a real slope of tectonized clay in Southern Italy is analyzed by a numerical model that considers changes in permeability induced by microfissure closure and opening during the wetting and drying processes resulting from climatic actions. Permeability model accounts for the changes in <span class="hlt">Pore</span> Size Distribution observed by Microscopy Intrusion Porosimetry. MIP tests are performed on representative samples of ground in initial conditions ("in situ" conditions) and final conditions (deformed sample after applying a wetting path that aims to reproduce the saturation of the soil under heavy rains). The resulting measurements allow for the characterization at microstructural level of the soil, identifying the distribution of dominant families <span class="hlt">pores</span> in the sample and its evolution under external actions. Moreover, comparison of <span class="hlt">pore</span> size density functions allows defining a microstructural parameter that depends on void ratio and degree of saturation and controls the variation of permeability. Model has been implemented in a thermo-hydro-mechanical code provided with a special boundary condition for climatic actions. Tool is used to analyze <span class="hlt">pore</span> <span class="hlt">pressure</span> measurements obtained in the tectonized clay slope. Results are analyzed at the light of the effect that permeability changes during wetting and drying have on the <span class="hlt">pore</span> <span class="hlt">pressure</span> regime.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_1");'>1</a></li> <li><a href="#" onclick='return showDiv("page_2");'>2</a></li> <li class="active"><span>3</span></li> <li><a href="#" onclick='return showDiv("page_4");'>4</a></li> <li><a href="#" onclick='return showDiv("page_5");'>5</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_3 --> <div id="page_4" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_2");'>2</a></li> <li><a href="#" onclick='return showDiv("page_3");'>3</a></li> <li class="active"><span>4</span></li> <li><a href="#" onclick='return showDiv("page_5");'>5</a></li> <li><a href="#" onclick='return showDiv("page_6");'>6</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="61"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017GML....37..441L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017GML....37..441L"><span>Variability of in situ sediment strength and <span class="hlt">pore</span> <span class="hlt">pressure</span> behavior of tidal estuary surface sediments</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Lucking, Greg; Stark, Nina; Lippmann, Thomas; Smyth, Stephen</p> <p>2017-10-01</p> <p>Tidal estuaries feature spatially and temporally varying sediment dynamics and characteristics. Particularly, the variability of geotechnical sediment parameters is still poorly understood, limiting the prediction of long-term sediment stability and dynamics. This paper presents results from an in situ investigation of surficial sediments (≤50 cm) in a tidal estuary in New Hampshire (USA), using a portable free fall penetrometer. The aim is to investigate variations in sediment strength and <span class="hlt">pore</span> <span class="hlt">pressure</span> behavior with regard to sediment type and seabed morphology. The study also provides a detailed analysis of high velocity impact <span class="hlt">pore</span> <span class="hlt">pressure</span> data to derive information about sediment type and permeability. The penetrometer was deployed 227 times, and the findings are correlated to 78 sediment samples. Differences in sediment strength and type were found when transitioning from tidal flats to the deeper channels. Finer-grained sediments located predominantly on the tidal flats appeared well consolidated with noticeable and spatially consistent sediment strength (reflected in an estimate of quasi-static bearing capacity qsbcmax 10 kPa). Sediments with higher sand content (>75%) showed more variations in strength relating to differences in gradation, and likely represent loose and poorly consolidated sands (qsbcmax 10-55 kPa). The rate at which the recorded excess <span class="hlt">pore</span> <span class="hlt">pressures</span> approached equilibrium after penetration was classified and related to sediment type. The data indicate that the development of excess <span class="hlt">pore</span> <span class="hlt">pressures</span> upon impact and during penetration may provide additional insight into the nature and layering of bed material, such as identifying a desiccated or over-consolidated dilative surficial layer. In summary, with varying sediment grain size distributions, bulk densities and morphology, sediment strength and <span class="hlt">pore</span> <span class="hlt">pressure</span> behavior can vary significantly within a tidal estuary.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19760039151&hterms=sonic+temperature&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3Dsonic%2Btemperature','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19760039151&hterms=sonic+temperature&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3Dsonic%2Btemperature"><span>The effects of <span class="hlt">pressure</span>, temperature, and <span class="hlt">pore</span> water on velocities in Westerly granite. [for seismic wave propagation</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Spencer, J. W., Jr.; Nur, A. M.</p> <p>1976-01-01</p> <p>A description is presented of an experimental assembly which has been developed to conduct concurrent measurements of compressional and shear wave velocities in rocks at high temperatures and confining <span class="hlt">pressures</span> and with independent control of the <span class="hlt">pore</span> <span class="hlt">pressure</span>. The apparatus was used in studies of the joint effects of temperature, external confining <span class="hlt">pressure</span>, and internal <span class="hlt">pore</span> water on sonic velocities in Westerly granite. It was found that at a given temperature, confining <span class="hlt">pressure</span> has a larger accelerating effect on compressional waves in dry rock, whereas at a given confining <span class="hlt">pressure</span>, temperature has a larger retarding effect on shear waves.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://pubs.er.usgs.gov/publication/70017363','USGSPUBS'); return false;" href="https://pubs.er.usgs.gov/publication/70017363"><span>Differential equations governing slip-induced <span class="hlt">pore-pressure</span> fluctuations in a water-saturated granular medium</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Iverson, R.M.</p> <p>1993-01-01</p> <p>Macroscopic frictional slip in water-saturated granular media occurs commonly during landsliding, surface faulting, and intense bedload transport. A mathematical model of dynamic <span class="hlt">pore-pressure</span> fluctuations that accompany and influence such sliding is derived here by both inductive and deductive methods. The inductive derivation shows how the governing differential equations represent the physics of the steadily sliding array of cylindrical fiberglass rods investigated experimentally by Iverson and LaHusen (1989). The deductive derivation shows how the same equations result from a novel application of Biot's (1956) dynamic mixture theory to macroscopic deformation. The model consists of two linear differential equations and five initial and boundary conditions that govern solid displacements and <span class="hlt">pore</span>-water <span class="hlt">pressures</span>. Solid displacements and water <span class="hlt">pressures</span> are strongly coupled, in part through a boundary condition that ensures mass conservation during irreversible <span class="hlt">pore</span> deformation that occurs along the bumpy slip surface. Feedback between this deformation and the <span class="hlt">pore-pressure</span> field may yield complex system responses. The dual derivations of the model help explicate key assumptions. For example, the model requires that the dimensionless parameter B, defined here through normalization of Biot's equations, is much larger than one. This indicates that solid-fluid coupling forces are dominated by viscous rather than inertial effects. A tabulation of physical and kinematic variables for the rod-array experiments of Iverson and LaHusen and for various geologic phenomena shows that the model assumptions commonly are satisfied. A subsequent paper will describe model tests against experimental data. ?? 1993 International Association for Mathematical Geology.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2006AGUFM.S33B0235M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2006AGUFM.S33B0235M"><span>2D Simulations of Earthquake Cycles at a Subduction Zone Based on a Rate and State Friction Law -Effects of <span class="hlt">Pore</span> Fluid <span class="hlt">Pressure</span> Changes-</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Mitsui, Y.; Hirahara, K.</p> <p>2006-12-01</p> <p>There have been a lot of studies that simulate large earthquakes occurring quasi-periodically at a subduction zone, based on the laboratory-derived rate-and-state friction law [eg. Kato and Hirasawa (1997), Hirose and Hirahara (2002)]. All of them assume that <span class="hlt">pore</span> fluid <span class="hlt">pressure</span> in the fault zone is constant. However, in the fault zone, <span class="hlt">pore</span> fluid <span class="hlt">pressure</span> changes suddenly, due to coseismic <span class="hlt">pore</span> dilatation [Marone (1990)] and thermal <span class="hlt">pressurization</span> [Mase and Smith (1987)]. If <span class="hlt">pore</span> fluid <span class="hlt">pressure</span> drops and effective normal stress rises, fault slip is decelerated. Inversely, if <span class="hlt">pore</span> fluid <span class="hlt">pressure</span> rises and effective normal stress drops, fault slip is accelerated. The effect of <span class="hlt">pore</span> fluid may cause slow slip events and low-frequency tremor [Kodaira et al. (2004), Shelly et al. (2006)]. For a simple spring model, how <span class="hlt">pore</span> dilatation affects slip instability was investigated [Segall and Rice (1995), Sleep (1995)]. When the rate of the slip becomes high, <span class="hlt">pore</span> dilatation occurs and <span class="hlt">pore</span> <span class="hlt">pressure</span> drops, and the rate of the slip is restrained. Then the inflow of <span class="hlt">pore</span> fluid recovers the <span class="hlt">pore</span> <span class="hlt">pressure</span>. We execute 2D earthquake cycle simulations at a subduction zone, taking into account such changes of <span class="hlt">pore</span> fluid <span class="hlt">pressure</span> following Segall and Rice (1995), in addition to the numerical scheme in Kato and Hirasawa (1997). We do not adopt hydrostatic <span class="hlt">pore</span> <span class="hlt">pressure</span> but excess <span class="hlt">pore</span> <span class="hlt">pressure</span> for initial condition, because upflow of dehydrated water seems to exist at a subduction zone. In our model, <span class="hlt">pore</span> fluid is confined to the fault damage zone and flows along the plate interface. The smaller the flow rate is, the later <span class="hlt">pore</span> <span class="hlt">pressure</span> recovers. Since effective normal stress keeps larger, the fault slip is decelerated and stress drop becomes smaller. Therefore the smaller flow rate along the fault zone leads to the shorter earthquake recurrence time. Thus, not only the frictional parameters and the subduction rate but also the fault zone permeability affects the recurrence time of</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016AGUFM.H13H1503T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016AGUFM.H13H1503T"><span>Assessment of <span class="hlt">pore</span> <span class="hlt">pressures</span> and specific storage within sedimentary strata overlying underground mines</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Timms, W.; David, K.; Barbour, L. S.</p> <p>2016-12-01</p> <p>Realistic values of specific storage (Ss) for groundwater systems are important to determine the spatial extent and timing of c <span class="hlt">pore</span> <span class="hlt">pressure</span> changes when the groundwater system is stressed. However, numerical groundwater models of underground excavations typically assume constant literature values of Ss. One part of our research program utilised high frequency <span class="hlt">pore</span> <span class="hlt">pressure</span> data to evaluate variability and changes in Ss within sedimentary strata overlying a longwall coal mine. <span class="hlt">Pore</span> <span class="hlt">pressure</span> data from a vertical series of 6 vibrating wire piezometers (50 to 278 m depth) recording at hourly intervals were compared with barometric <span class="hlt">pressure</span> data over a period of several years, including data before and during mining. The site was located near the centre of a longwall panel that extracted 3 m of coal at a depth of 330 m. The data was processed to calculate loading efficiency and Ss values by multi-method analyses of barometric and earth tide responses. In situ Ss results varied over one to two orders of magnitude and indicated that Ss changed before and after excavation of underlying coal seams. The vertical leakage of groundwater within the constrained zone ( 10 to 150 m depth) was found to be limited, although some degree of vertical hydraulic connectivity was observed. Depressurization was evident in the fractured zone directly overlying the coal seam, and Ss changes at 250 m depth indicated this confined aquifer may have become unconfined. Our results demonstrate that high frequency <span class="hlt">pore</span> <span class="hlt">pressure</span> data can provide realistic Ss values. In situ Ss values were an order of magnitude lower than Ss measured by geomechnical tests of cores, and were significantly different to textbook values set in most local groundwater models. The timing and extent of groundwater level drawdown predicted by models may therefore be underestimated. We have shown, for the first time, that variability of Ss can be significant, and that these changes can provide important insights into how</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015AGUFM.H51L1556Y','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AGUFM.H51L1556Y"><span>Effect of <span class="hlt">Pore</span> <span class="hlt">Pressure</span> on Slip Failure of an Impermeable Fault: A Coupled Micro Hydro-Geomechanical Model</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Yang, Z.; Juanes, R.</p> <p>2015-12-01</p> <p>The geomechanical processes associated with subsurface fluid injection/extraction is of central importance for many industrial operations related to energy and water resources. However, the mechanisms controlling the stability and slip motion of a preexisting geologic fault remain poorly understood and are critical for the assessment of seismic risk. In this work, we develop a coupled hydro-geomechanical model to investigate the effect of fluid injection induced <span class="hlt">pressure</span> perturbation on the slip behavior of a sealing fault. The model couples single-phase flow in the <span class="hlt">pores</span> and mechanics of the solid phase. Granular packs (see example in Fig. 1a) are numerically generated where the grains can be either bonded or not, depending on the degree of cementation. A <span class="hlt">pore</span> network is extracted for each granular pack with <span class="hlt">pore</span> body volumes and <span class="hlt">pore</span> throat conductivities calculated rigorously based on geometry of the local <span class="hlt">pore</span> space. The <span class="hlt">pore</span> fluid <span class="hlt">pressure</span> is solved via an explicit scheme, taking into account the effect of deformation of the solid matrix. The mechanics part of the model is solved using the discrete element method (DEM). We first test the validity of the model with regard to the classical one-dimensional consolidation problem where an analytical solution exists. We then demonstrate the ability of the coupled model to reproduce rock deformation behavior measured in triaxial laboratory tests under the influence of <span class="hlt">pore</span> <span class="hlt">pressure</span>. We proceed to study the fault stability in presence of a <span class="hlt">pressure</span> discontinuity across the impermeable fault which is implemented as a plane with its intersected <span class="hlt">pore</span> throats being deactivated and thus obstructing fluid flow (Fig. 1b, c). We focus on the onset of shear failure along preexisting faults. We discuss the fault stability criterion in light of the numerical results obtained from the DEM simulations coupled with <span class="hlt">pore</span> fluid flow. The implication on how should faults be treated in a large-scale continuum model is also presented.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016AGUFM.S52B..05Z','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016AGUFM.S52B..05Z"><span>Geomechanical modelling of induced seismicity using Coulomb stress and <span class="hlt">pore</span> <span class="hlt">pressure</span> changes</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Zhao, B.; Shcherbakov, R.</p> <p>2016-12-01</p> <p>In recent years, there has been a dramatic increase in seismicity (earthquakes) due to anthropogenic activities related to the unconventional oil and gas exploration in the Western Canada Sedimentary Basin (WCSB). There are compelling evidences that hydraulic fracturing and wastewater injection operations play a key role in induced seismicity in the WCSB; however, their physical mechanisms are still not fully understood. Therefore, this study focuses on exploring the physical mechanisms of induced seismicity and developing a realistic geomechanical model by incorporating the past seismicity and well production data. In this work, we model the Coulomb stress changes due to past moderate (magnitude greater than 3 with known fault plane solutions) induced earthquakes and <span class="hlt">pore</span> <span class="hlt">pressure</span> changes due to wastewater injection in Alberta, specifically in Fox Creek and Fort St. John areas. Relationships between Coulombs stress changes, fault geometry and orientation and subsequent earthquake locations are tested. Subsurface flow due to injection well operations is studied to model the <span class="hlt">pore</span> <span class="hlt">pressure</span> changes in time and space, using known well production data, which include well types, well locations and water extraction and injection rates. By modelling the changes in <span class="hlt">pore</span> <span class="hlt">pressure</span> and Coulomb stress, we aim at constraining the time scale of occurrence of possible future earthquakes. The anticipating results can help to control the parameters of anthropogenic energy related operations such as hydraulic fracturing and wastewater injection in mitigating the risk due to induced seismicity.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017AGUFMMR41B0410S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017AGUFMMR41B0410S"><span>Micro X-ray CT imaging of <span class="hlt">pore</span>-scale changes in unconsolidated sediment under confining <span class="hlt">pressure</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Schindler, M.; Prasad, M.</p> <p>2017-12-01</p> <p>Micro X-ray computed tomography was used to image confining-<span class="hlt">pressure</span> induced changes in a dry, unconsolidated quartz sand pack while simultaneously recording ultrasonic P-wave velocities. The experiments were performed under in-situ <span class="hlt">pressure</span> of up to 4000 psi. The majority of digital rock physics studies rely on micro CT images obtained under ambient <span class="hlt">pressure</span> and temperature conditions although effective rock properties strongly depend on in situ conditions. Goal of this work is to be able to obtain micro CT images of rock samples while <span class="hlt">pore</span> and confining <span class="hlt">pressure</span> is applied. Simultaneously we recorded ultrasonic P-wave velocities. The combination of imaging and velocity measurements provides insight in <span class="hlt">pore</span>-scale changes in the rock and their influence on elastic properties. We visually observed a reduction in porosity by more than a third of the initial value as well as extensive grain damage, changes in <span class="hlt">pore</span> and grain size distribution and an increase in contact number and contact radius with increasing confining <span class="hlt">pressure</span>. An increase in measured ultrasonic P-wave velocities with increasing <span class="hlt">pressure</span> was observed. We used porosity, contact number and contact radius obtained from micro CT images to model P-wave velocity with the contact-radius model by Bachrach et al. (1998). Our observations showed that the frame of unconsolidated sediments is significantly altered starting at <span class="hlt">pressures</span> of only 1000 psi. This finding indicates that common assumptions in rock physics models (the solid frame remains unchanged) are violated for unconsolidated sediments. The effects on the solid frame should be taken into account when modeling the <span class="hlt">pressure</span> dependence of elastic rock properties.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ijege.uniroma1.it/rivista/5th-international-conference-on-debris-flow-hazards-mitigation-mechanics-prediction-and-assessment','USGSPUBS'); return false;" href="http://www.ijege.uniroma1.it/rivista/5th-international-conference-on-debris-flow-hazards-mitigation-mechanics-prediction-and-assessment"><span>A two-phase debris-flow model that includes coupled evolution of volume fractions, granular dilatancy, and <span class="hlt">pore</span>-fluid <span class="hlt">pressure</span></span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>George, David L.; Iverson, Richard M.</p> <p>2011-01-01</p> <p><span class="hlt">Pore</span>-fluid <span class="hlt">pressure</span> plays a crucial role in debris flows because it counteracts normal stresses at grain contacts and thereby reduces intergranular friction. <span class="hlt">Pore-pressure</span> feedback accompanying debris deformation is particularly important during the onset of debrisflow motion, when it can dramatically influence the balance of forces governing downslope acceleration. We consider further effects of this feedback by formulating a new, depth-averaged mathematical model that simulates coupled evolution of granular dilatancy, solid and fluid volume fractions, <span class="hlt">pore</span>-fluid <span class="hlt">pressure</span>, and flow depth and velocity during all stages of debris-flow motion. To illustrate implications of the model, we use a finite-volume method to compute one-dimensional motion of a debris flow descending a rigid, uniformly inclined slope, and we compare model predictions with data obtained in large-scale experiments at the USGS debris-flow flume. Predictions for the first 1 s of motion show that increasing <span class="hlt">pore</span> <span class="hlt">pressures</span> (due to debris contraction) cause liquefaction that enhances flow acceleration. As acceleration continues, however, debris dilation causes dissipation of <span class="hlt">pore</span> <span class="hlt">pressures</span>, and this dissipation helps stabilize debris-flow motion. Our numerical predictions of this process match experimental data reasonably well, but predictions might be improved by accounting for the effects of grain-size segregation.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013AGUFMMR13A2242H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013AGUFMMR13A2242H"><span>Influence of <span class="hlt">Pore</span>-Fluid <span class="hlt">Pressure</span> on Elastic Wave Velocity and Electrical Conductivity in Water-Saturated Rocks</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Higuchi, A.; Watanabe, T.</p> <p>2013-12-01</p> <p><span class="hlt">Pore</span>-fluid <span class="hlt">pressure</span> in seismogenic zones can play a key role in the occurrence of earthquakes (e.g., Sibson, 2009). Its evaluation via geophysical observations can lead to a good understanding of seismic activities. The evaluation requires a thorough understanding of the influence of the <span class="hlt">pore</span>-fluid <span class="hlt">pressure</span> on geophysical observables like seismic velocity and electrical conductivity. We have studied the influence of <span class="hlt">pore</span>-fluid <span class="hlt">pressure</span> on elastic wave velocity and electrical conductivity in water-saturated rocks. Fine grained (100-500μm) biotite granite (Aji, Kagawa pref., Japan) was used as rock samples. The density is 2.658-2.668 g/cm3, and the porosity 0.68-0.87%. The sample is composed of 52.8% plagioclase, 36.0% Quartz, 3.0% K-feldspar, 8.2% biotite. SEM images show that a lot of grain boundaries are open. Few intracrystalline cracks were observed. Following the method proposed by David and Zimmerman (2012), the distribution function of crack aspect ratio was evaluated from the <span class="hlt">pressure</span> dependence of compressional and shear wave velocities in a dry sample. Cylindrical sample has dimensions of 25 mm in diameter and 30 mm in length, and saturated with 0.01 mol/l KCl aqueous solution. Compressional and shear wave velocities were measured with the pulse transmission technique (PZT transducers, f=2 MHz), and electrical conductivity the two-electrode method (Ag-AgCl electrodes, f=1 Hz-100 kHz). Simultaneous measurements of velocities and conductivity were made using a 200 MPa hydrostatic <span class="hlt">pressure</span> vessel, in which confining and <span class="hlt">pore</span>-fluid <span class="hlt">pressures</span> can be separately controlled. The <span class="hlt">pore</span>-fluid is electrically insulated from the metal work of the <span class="hlt">pressure</span> vessel by using a newly designed plastic device (Watanabe and Higuchi, 2013). The confining <span class="hlt">pressure</span> was progressively increased up to 25 MPa, while the <span class="hlt">pore</span>-fluid <span class="hlt">pressure</span> was kept at 0.1 MPa. It took five days or longer for the electrical conductivity to become stationary after increasing the confining <span class="hlt">pressure</span></p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016EGUGA..1818293G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016EGUGA..1818293G"><span>Experimental Studies of Dynamic Fault Weakening Due to Thermal <span class="hlt">Pressurization</span> of <span class="hlt">Pore</span> Fluids</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Goldsby, David; Tullis, Terry; Platt, John; Okazaki, Keishi</p> <p>2016-04-01</p> <p>High-velocity friction experiments and geophysical observations suggest that mature faults weaken dramatically during seismic slip. However, while many coseismic weakening mechanisms have been proposed, it is still unclear which mechanisms are most important or how the efficiency of weakening varies within the seismogenic zone. Thermal <span class="hlt">pressurization</span> is one possible coseismic weakening mechanism driven by the thermal expansion of native <span class="hlt">pore</span> fluids, which leads to elevated <span class="hlt">pore</span> <span class="hlt">pressures</span> and significant coseismic weakening. While thermal <span class="hlt">pressurization</span> has been studied theoretically for many decades, and invoked in recent earthquake simulations, its activation in laboratory experiments has remained elusive. Several high-speed friction studies have yielded indirect evidence for thermal <span class="hlt">pressurization</span>, yet none has directly linked with existing theoretical models or the relevant physical parameters, such as permeability, slip, and slip rate, that control the weakening rate. To fill this gap, we are conducting thermal <span class="hlt">pressurization</span> experiments on fluid-saturated, low-permeability rocks (Frederick diabase) at slip rates up to ~5 mm/s, at constant confining <span class="hlt">pressures</span> in the range 21-149 MPa and initial imposed <span class="hlt">pore</span> <span class="hlt">pressures</span> in the range 10-25 MPa. The impractically low permeability of the as-is diabase, ~10-23 m2, is increased prior to the test by thermal cracking, yielding measured permeabilities in the range 1.3*10-18 to 6.1*10-19 m2. These values of permeability are high enough to allow sample saturation over one to several days, but low enough to confine the elevated <span class="hlt">pore</span> <span class="hlt">pressures</span> generated by frictional heating during rapid sliding. Our experiments reveal a rapid decay of shear stress following a step-change in velocity from 10 μm/s to 4.8 mm/s. In one test, the decrease in shear stress of ~25% over the first 28 mm of slip at 4.8 mm/s agrees closely with the theoretical solution for slip on a plane (Rice [2006]), with an inferred slip-weakening distance of ~500</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://pubs.er.usgs.gov/publication/70017601','USGSPUBS'); return false;" href="https://pubs.er.usgs.gov/publication/70017601"><span>A <span class="hlt">pore-pressure</span> diffusion model for estimating landslide-inducing rainfall</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Reid, M.E.</p> <p>1994-01-01</p> <p>Many types of landslide movement are induced by large rainstorms, and empirical rainfall intensity/duration thresholds for initiating movement have been determined for various parts of the world. In this paper, I present a simple <span class="hlt">pressure</span> diffusion model that provides a physically based hydrologic link between rainfall intensity/duration at the ground surface and destabilizing <span class="hlt">pore</span>-water <span class="hlt">pressures</span> at depth. The model approximates rainfall infiltration as a sinusoidally varying flux over time and uses physical parameters that can be determined independently. Using a comprehensive data set from an intensively monitored landslide, I demonstrate that the model is capable of distinguishing movement-inducing rainstorms. -Author</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/biblio/1203930-effects-pore-distributions-ductility-thin-walled-high-pressure-die-cast-magnesium','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/1203930-effects-pore-distributions-ductility-thin-walled-high-pressure-die-cast-magnesium"><span>Effects of <span class="hlt">Pore</span> Distributions on Ductility of Thin-Walled High <span class="hlt">Pressure</span> Die-Cast Magnesium</span></a></p> <p><a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a></p> <p>Choi, Kyoo Sil; Li, Dongsheng; Sun, Xin</p> <p>2013-06-01</p> <p>In this paper, a microstructure-based three-dimensional (3D) finite element modeling method is adopted to investigate the effects of porosity in thin-walled high <span class="hlt">pressure</span> die-cast (HPDC) Magnesium alloys on their ductility. For this purpose, the cross-sections of AM60 casting samples are first examined using optical microscope and X-ray tomography to obtain the general information on the <span class="hlt">pore</span> distribution features. The experimentally observed <span class="hlt">pore</span> distribution features are then used to generate a series of synthetic microstructure-based 3D finite element models with different <span class="hlt">pore</span> volume fractions and <span class="hlt">pore</span> distribution features. Shear and ductile damage models are adopted in the finite element analyses tomore » induce the fracture by element removal, leading to the prediction of ductility. The results in this study show that the ductility monotonically decreases as the <span class="hlt">pore</span> volume fraction increases and that the effect of ‘skin region’ on the ductility is noticeable under the condition of same local <span class="hlt">pore</span> volume fraction in the center region of the sample and its existence can be beneficial for the improvement of ductility. The further synthetic microstructure-based 3D finite element analyses are planned to investigate the effects of <span class="hlt">pore</span> size and <span class="hlt">pore</span> size distribution.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010AGUFMMR11B1879H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010AGUFMMR11B1879H"><span><span class="hlt">Pore</span>-Lining Composition and Capillary Breakthrough <span class="hlt">Pressure</span> of Mudstone Caprocks: Sealing Efficiency of Geologic CO2 Storage Sites</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Heath, J. E.; Dewers, T. A.; McPherson, B. J.; Kotula, P. G.</p> <p>2010-12-01</p> <p>Subsurface containment of CO2 is predicated on effective caprock sealing. Many previous studies have relied on macroscopic measurements of capillary breakthrough <span class="hlt">pressure</span> and other petrophysical properties without direct examination of solid phases that line <span class="hlt">pore</span> networks and directly contact fluids. However, <span class="hlt">pore</span>-lining phases strongly contribute to sealing behavior through interfacial interactions among CO2, brine, and the mineral or non-mineral phases. Our high resolution (i.e., sub-micron) examination of the composition of <span class="hlt">pore</span>-lining phases of several continental and marine mudstones indicates that sealing efficiency (i.e., breakthrough <span class="hlt">pressure</span>) is governed by <span class="hlt">pore</span> shapes and <span class="hlt">pore</span>-lining phases that are not identifiable except through direct characterization of <span class="hlt">pores</span>. Bulk X-ray diffraction data does not indicate which phases line the <span class="hlt">pores</span> and may be especially lacking for mudstones with organic material. Organics can line <span class="hlt">pores</span> and may represent once-mobile phases that modify the wettability of an originally clay-lined <span class="hlt">pore</span> network. For shallow formations (i.e., < ~800 m depth), interfacial tension and contact angles result in breakthrough <span class="hlt">pressures</span> that may be as high as those needed to fracture the rock—thus, in the absence of fractures, capillary sealing efficiency is indicated. Deeper seals have poorer capillary sealing if mica-like wetting dominates the wettability. We thank the U.S. Department of Energy’s National Energy Technology Laboratory and the Office of Basic Energy Sciences, and the Southeast and Southwest Carbon Sequestration Partnerships for supporting this work. Sandia National Laboratories is a multi-program laboratory operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Company, for the U.S. Department of Energy’s National Nuclear Security Administration under contract DE-AC04-94AL85000.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/CFR-2010-title14-vol2/pdf/CFR-2010-title14-vol2-sec91-144.pdf','CFR'); return false;" href="https://www.gpo.gov/fdsys/pkg/CFR-2010-title14-vol2/pdf/CFR-2010-title14-vol2-sec91-144.pdf"><span>14 CFR 91.144 - Temporary restriction on flight operations during <span class="hlt">abnormally</span> high barometric <span class="hlt">pressure</span> conditions.</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collectionCfr.action?selectedYearFrom=2010&page.go=Go">Code of Federal Regulations, 2010 CFR</a></p> <p></p> <p>2010-01-01</p> <p>... during <span class="hlt">abnormally</span> high barometric <span class="hlt">pressure</span> conditions. 91.144 Section 91.144 Aeronautics and Space... flight operations during <span class="hlt">abnormally</span> high barometric <span class="hlt">pressure</span> conditions. (a) Special flight restrictions. When any information indicates that barometric <span class="hlt">pressure</span> on the route of flight currently exceeds or...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://pubs.er.usgs.gov/publication/70013126','USGSPUBS'); return false;" href="https://pubs.er.usgs.gov/publication/70013126"><span>CONCEPTUAL MODEL FOR ORIGIN OF <span class="hlt">ABNORMALLY</span> <span class="hlt">PRESSURED</span> GAS ACCUMULATIONS IN LOW-PERMEABILITY RESERVOIRS.</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Law, B.E.; Dickinson, W.W.</p> <p>1985-01-01</p> <p>The paper suggests that overpressured and underpressured gas accumulations of this type have a common origin. In basins containing overpressured gas accumulations, rates of thermogenic gas accumulation exceed gas loss, causing fluid (gas) <span class="hlt">pressure</span> to rise above the regional hydrostatic <span class="hlt">pressure</span>. Free water in the larger <span class="hlt">pores</span> is forced out of the gas generation zone into overlying and updip, normally <span class="hlt">pressured</span>, water-bearing rocks. While other diagenetic processes continue, a <span class="hlt">pore</span> network with very low permeability develops. As a result, gas accumulates in these low-permeability reservoirs at rates higher than it is lost. In basins containing underpressured gas accumulations, rates of gas generation and accumulation are less than gas loss. The basin-center gas accumulation persists, but because of changes in the basin dynamics, the overpressured accumulation evolves into an underpressured system.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015AGUFMMR51A..07D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AGUFMMR51A..07D"><span><span class="hlt">Pore</span> Characterization of Shale Rock and Shale Interaction with Fluids at Reservoir <span class="hlt">Pressure</span>-Temperature Conditions Using Small-Angle Neutron Scattering</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ding, M.; Hjelm, R.; Watkins, E.; Xu, H.; Pawar, R.</p> <p>2015-12-01</p> <p>Oil/gas produced from unconventional reservoirs has become strategically important for the US domestic energy independence. In unconventional realm, hydrocarbons are generated and stored in nanopores media ranging from a few to hundreds of nanometers. Fundamental knowledge of coupled thermo-hydro-mechanical-chemical (THMC) processes that control fluid flow and propagation within nano-<span class="hlt">pore</span> confinement is critical for maximizing unconventional oil/gas production. The size and confinement of the nanometer <span class="hlt">pores</span> creates many complex rock-fluid interface interactions. It is imperative to promote innovative experimental studies to decipher physical and chemical processes at the nanopore scale that govern hydrocarbon generation and mass transport of hydrocarbon mixtures in tight shale and other low permeability formations at reservoir <span class="hlt">pressure</span>-temperature conditions. We have carried out laboratory investigations exploring quantitative relationship between <span class="hlt">pore</span> characteristics of the Wolfcamp shale from Western Texas and the shale interaction with fluids at reservoir P-T conditions using small-angle neutron scattering (SANS). We have performed SANS measurements of the shale rock in single fluid (e.g., H2O and D2O) and multifluid (CH4/(30% H2O+70% D2O)) systems at various <span class="hlt">pressures</span> up to 20000 psi and temperature up to 150 oF. Figure 1 shows our SANS data at different <span class="hlt">pressures</span> with H2O as the <span class="hlt">pressure</span> medium. Our data analysis using IRENA software suggests that the principal changes of <span class="hlt">pore</span> volume in the shale occurred on smaller than 50 nm <span class="hlt">pores</span> and <span class="hlt">pressure</span> at 5000 psi (Figure 2). Our results also suggest that with increasing P, more water flows into <span class="hlt">pores</span>; with decreasing P, water is retained in the <span class="hlt">pores</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20110023866','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20110023866"><span>Explicit <span class="hlt">Pore</span> <span class="hlt">Pressure</span> Material Model in Carbon-Cloth Phenolic</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Gutierrez-Lemini, Danton; Ehle, Curt</p> <p>2003-01-01</p> <p>An explicit material model that uses predicted <span class="hlt">pressure</span> in the <span class="hlt">pores</span> of a carbon-cloth phenolic (CCP) composite has been developed. This model is intended to be used within a finite-element model to predict phenomena specific to CCP components of solid-fuel-rocket nozzles subjected to high operating temperatures and to mechanical stresses that can be great enough to cause structural failures. Phenomena that can be predicted with the help of this model include failures of specimens in restrained-thermal-growth (RTG) tests, pocketing erosion, and ply lifting</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017GeoJI.211.1494O','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017GeoJI.211.1494O"><span>Spectral element modelling of seismic wave propagation in visco-elastoplastic media including excess-<span class="hlt">pore</span> <span class="hlt">pressure</span> development</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Oral, Elif; Gélis, Céline; Bonilla, Luis Fabián; Delavaud, Elise</p> <p>2017-12-01</p> <p>Numerical modelling of seismic wave propagation, considering soil nonlinearity, has become a major topic in seismic hazard studies when strong shaking is involved under particular soil conditions. Indeed, when strong ground motion propagates in saturated soils, <span class="hlt">pore</span> <span class="hlt">pressure</span> is another important parameter to take into account when successive phases of contractive and dilatant soil behaviour are expected. Here, we model 1-D seismic wave propagation in linear and nonlinear media using the spectral element numerical method. The study uses a three-component (3C) nonlinear rheology and includes <span class="hlt">pore-pressure</span> excess. The 1-D-3C model is used to study the 1987 Superstition Hills earthquake (ML 6.6), which was recorded at the Wildlife Refuge Liquefaction Array, USA. The data of this event present strong soil nonlinearity involving <span class="hlt">pore-pressure</span> effects. The ground motion is numerically modelled for different assumptions on soil rheology and input motion (1C versus 3C), using the recorded borehole signals as input motion. The computed acceleration-time histories show low-frequency amplification and strong high-frequency damping due to the development of <span class="hlt">pore</span> <span class="hlt">pressure</span> in one of the soil layers. Furthermore, the soil is found to be more nonlinear and more dilatant under triaxial loading compared to the classical 1C analysis, and significant differences in surface displacements are observed between the 1C and 3C approaches. This study contributes to identify and understand the dominant phenomena occurring in superficial layers, depending on local soil properties and input motions, conditions relevant for site-specific studies.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018BVol...80...19H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018BVol...80...19H"><span>Deformation of volcanic materials by <span class="hlt">pore</span> <span class="hlt">pressurization</span>: analog experiments with simplified geometry</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Hyman, David; Bursik, Marcus</p> <p>2018-03-01</p> <p>The <span class="hlt">pressurization</span> of <span class="hlt">pore</span> fluids plays a significant role in deforming volcanic materials; however, understanding of this process remains incomplete, especially scenarios accompanying phreatic eruptions. Analog experiments presented here use a simple geometry to study the mechanics of this type of deformation. Syrup was injected into the base of a sand medium, simulating the permeable flow of fluids through shallow volcanic systems. The experiments examined surface deformation over many source depths and <span class="hlt">pressures</span>. Surface deformation was recorded using a Microsoft® Kinect™ sensor, generating high-spatiotemporal resolution lab-scale digital elevation models (DEMs). The behavior of the system is controlled by the ratio of <span class="hlt">pore</span> <span class="hlt">pressure</span> to lithostatic loading (λ =p/ρ g D). For λ <10, deformation was accommodated by high-angle, reversed-mechanism shearing along which fluid preferentially flowed, leading to a continuous feedback between deformation and <span class="hlt">pressurization</span> wherein higher <span class="hlt">pressure</span> ratios yielded larger deformations. For λ >10, fluid expulsion from the layer was much faster, vertically fracturing to the surface with larger <span class="hlt">pressure</span> ratios yielding less deformation. The temporal behavior of deformation followed a characteristic evolution that produced an approximately exponential increase in deformation with time until complete layer penetration. This process is distinguished from magmatic sources in continuous geodetic data by its rapidity and characteristic time evolution. The time evolution of the experiments compares well with tilt records from Mt. Ontake, Japan, in the lead-up to the deadly 2014 phreatic eruption. Improved understanding of this process may guide the evolution of magmatic intrusions such as dikes, cone sheets, and cryptodomes and contribute to caldera resurgence or deformation that destabilizes volcanic flanks.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_2");'>2</a></li> <li><a href="#" onclick='return showDiv("page_3");'>3</a></li> <li class="active"><span>4</span></li> <li><a href="#" onclick='return showDiv("page_5");'>5</a></li> <li><a href="#" onclick='return showDiv("page_6");'>6</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_4 --> <div id="page_5" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_3");'>3</a></li> <li><a href="#" onclick='return showDiv("page_4");'>4</a></li> <li class="active"><span>5</span></li> <li><a href="#" onclick='return showDiv("page_6");'>6</a></li> <li><a href="#" onclick='return showDiv("page_7");'>7</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="81"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016RMRE...49.2333P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016RMRE...49.2333P"><span>Hydromechanical Rock Mass Fatigue in Deep-Seated Landslides Accompanying Seasonal Variations in <span class="hlt">Pore</span> <span class="hlt">Pressures</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Preisig, Giona; Eberhardt, Erik; Smithyman, Megan; Preh, Alexander; Bonzanigo, Luca</p> <p>2016-06-01</p> <p>The episodic movement of deep-seated landslides is often governed by the presence of high <span class="hlt">pore</span> <span class="hlt">pressures</span> and reduced effective stresses along active shear surfaces. <span class="hlt">Pore</span> <span class="hlt">pressures</span> are subject to cyclic fluctuation under seasonal variations of groundwater recharge, resulting in an intermittent movement characterized by acceleration-deceleration phases. However, it is not always clear why certain acceleration phases reach alarming levels without a clear trigger (i.e., in the absence of an exceptional <span class="hlt">pore</span> <span class="hlt">pressure</span> event). This paper presents a conceptual framework linking hydromechanical cycling, progressive failure and fatigue to investigate and explain the episodic behavior of deep-seated landslides using the Campo Vallemaggia landslide in Switzerland as a case study. A combination of monitoring data and advanced numerical modeling is used. The principal processes forcing the slope into a critical disequilibrium state are analyzed as a function of rock mass damage and fatigue. Modeling results suggest that during periods of slope acceleration, the rock slope experiences localized fatigue and gradual weakening through slip along pre-existing natural fractures and yield of critically stressed intact rock bridges. At certain intervals, pockets of critically weakened rock may produce a period of enhanced slope movement in response to a small <span class="hlt">pore</span> <span class="hlt">pressure</span> increase similar to those routinely experienced each year. Accordingly, the distribution and connectivity of pre-existing permeable planes of weakness play a central role. These structures are often related to the rock mass's tectonic history or initiate (and dilate) in response to stress changes that disturb the entire slope, such as glacial unloading or seismic loading via large earthquakes. The latter is discussed in detail in a companion paper to this (Gischig et al., Rock Mech Rock Eng, 2015). The results and framework presented further demonstrate that episodic movement and progressive failure of deep</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017EGUGA..1917309D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017EGUGA..1917309D"><span>Recharge and Transient <span class="hlt">Pore</span> <span class="hlt">Pressure</span> Propagation in Steep Alpine Mountain Slopes near Poschiavo, Switzerland</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>de Palézieux, Larissa; Loew, Simon; Zwahlen, Peter</p> <p>2017-04-01</p> <p>Within the scope of planning a hydropower pump storage plant in the Poschiavo valley by Lagobianco SA (Repower AG), numerous cored boreholes with depths of 50 to 300 m were drilled at elevations between 963 and 2538 m a.s.l.. In several boreholes Lugeon and transient <span class="hlt">pressure</span> packer tests were executed at various depths and <span class="hlt">pore</span> water <span class="hlt">pressure</span> sensors were properly installed in short monitoring intervals. Several of the boreholes intersect large suspended rock slides showing the characteristic zones of highly fragmented rock mass above a kakirite layer of several tens of meters thickness. This study presents long term transient <span class="hlt">pressure</span> records from these deep boreholes and relates them to seasonal recharge trends from snow melt and summer rainstorm events. Annual <span class="hlt">pore</span> <span class="hlt">pressure</span> amplitudes at depths between 45 and 278 meters, range between 4 and 40 meters. Recharge from snow melt water production is obtained from the Degree-Day Method (Rango and Martinec, 1995), despite a considerable distance between the meteorological station and the location of the boreholes. First estimations of storage properties of the aquifers intersected by the boreholes are determined by fitting a combined snow melt and precipitation <span class="hlt">pressure</span> function to the observed (delayed and attenuated) <span class="hlt">pore</span> <span class="hlt">pressure</span> records using a convolution of the one-dimensional <span class="hlt">pressure</span> diffusion equation for a semi-infinite aquifer of constant thickness (De Marsily, 1986). Initial hydraulic conductivity values were taken directly from hydraulic tests executed by Lagobianco SA in similar rock types (Figi et al., 2014). For most boreholes this strongly simplified approach yields impressively good fits of the transient <span class="hlt">pressure</span> records and specific storage/yield values, which vary significantly as a function of sensor depth below the piezometric level. Values range from 1e-6 m-1 to 5e-4 m-1 for confined gneiss-schists aquifers and around 3e-2 m-1 for phreatic aquifers, where <span class="hlt">pore</span> <span class="hlt">pressure</span> sensors are located only</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2006JGRB..111.4103G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2006JGRB..111.4103G"><span>Characterization of excess <span class="hlt">pore</span> <span class="hlt">pressures</span> at the toe of the Nankai accretionary complex, Ocean Drilling Program sites 1173, 1174, and 808: Results of one-dimensional modeling</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Gamage, K.; Screaton, E.</p> <p>2006-04-01</p> <p>Elevated fluid <span class="hlt">pore</span> <span class="hlt">pressures</span> play a critical role in the development of accretionary complexes, including the development of the décollement zone. In this study, we used measured permeabilities of core samples from Ocean Drilling Program (ODP) Leg 190 to develop a permeability-porosity relationship for hemipelagic sediments at the toe of the Nankai accretionary complex. This permeability-porosity relationship was used in a one-dimensional loading and fluid flow model to simulate excess <span class="hlt">pore</span> <span class="hlt">pressures</span> and porosities. Simulated excess <span class="hlt">pore</span> <span class="hlt">pressure</span> ratios (as a fraction of lithostatic <span class="hlt">pressure</span>-hydrostatic <span class="hlt">pressure</span>) using the best fit permeability-porosity relationship were lower than predicted from previous studies. We then tested sensitivity of excess <span class="hlt">pore</span> <span class="hlt">pressure</span> ratios in the underthrust sediments to bulk permeability, lateral stress in the prism, and a hypothetical low-permeability barrier at the décollement. Our results demonstrated significant increase in <span class="hlt">pore</span> <span class="hlt">pressures</span> below the décollement with lower bulk permeability, such as obtained by using the lower boundary of permeability-porosity data, or when a low-permeability barrier is added at the décollement. In contrast, <span class="hlt">pore</span> <span class="hlt">pressures</span> in the underthrust sediments demonstrated less sensitivity to added lateral stresses in the prism, although the profile of the excess <span class="hlt">pore</span> <span class="hlt">pressure</span> ratio is affected. Both simulations with lateral stress and a low-permeability barrier at the décollement resulted in sharp increases in porosity at the décollement, similar to that observed in measured porosities. Furthermore, in both scenarios, maximum excess <span class="hlt">pore</span> <span class="hlt">pressure</span> ratios were found at the décollement, suggesting that either of these factors would contribute to stable sliding along the décollement.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/servlets/purl/1436641','SCIGOV-STC'); return false;" href="https://www.osti.gov/servlets/purl/1436641"><span>Measuring the effects of <span class="hlt">pore-pressure</span> changes on seismic amplitude using crosswell continuous active-source seismic monitoring (CASSM)</span></a></p> <p><a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a></p> <p>Marchesini, Pierpaolo; Daley, Thomas; Ajo-Franklin, Jonathan</p> <p></p> <p>Monitoring of time-varying reservoir properties, such as the state of stress, is a primary goal of geophysical investigations, including for geological sequestration of CO 2, enhanced hydrocarbon recovery (EOR), and other subsurface engineering activities. In this work, we used Continuous Active-Source Seismic Monitoring (CASSM), with cross-well geometry, to measure variation in seismic coda amplitude, as a consequence of effective stress change (in the form of changes in <span class="hlt">pore</span> fluid <span class="hlt">pressure</span>). To our knowledge, the presented results are the first in-situ example of such crosswell measurement at reservoir scale and in field conditions. Data compliment the findings of our previous workmore » which investigated the relationship between <span class="hlt">pore</span> fluid <span class="hlt">pressure</span> and seismic velocity (velocity-stress sensitivity) using the CASSM system at the same field site (Marchesini et al., 2017, in review). We find that P-wave coda amplitude decreases with decreasing <span class="hlt">pore</span> <span class="hlt">pressure</span> (increasing effective stress).« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014AGUFMNH43A3812J','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014AGUFMNH43A3812J"><span>Movement of Landslide Triggered by Bedrock Exfiltration with Nonuniform <span class="hlt">Pore</span> <span class="hlt">Pressure</span> Distribution</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Jan, C. D.; Jian, Z. K.</p> <p>2014-12-01</p> <p>Landslides are common phenomena of sediment movement in mountain areas and usually pose severe risks to people and infrastructure around those areas. The occurrence of landslides is influenced by groundwater dynamics and bedrock characteristics as well as by rainfall and soil-mass properties. The bedrock may drain or contribute to groundwater in the overlying soil mass, depending on the hydraulic conductivity, degree of fracturing, saturation, and hydraulic head. Our study here is based on the model proposed by Iverson (2005). The model describes the relation between landslide displacement and the shear-zone dilation/contraction of <span class="hlt">pore</span> water <span class="hlt">pressure</span>. To study landslide initiation and movement, a block soil mass sliding down an inclined beck-rock plane is governed by Newton's equation of motion, while both the bedrock exfiltration and excess <span class="hlt">pore</span> <span class="hlt">pressure</span> induced by dilatation or contraction of basal shear zone are described by diffusion equations. The Chebyshev collocation method was used to transform the governing equations to a system of first-order ordinary differential equations, without the need of iteration. Then a fourth-order Runge-Kutta scheme was used to solve these ordinary differential equations. The effects of nonuniform bedrock exfiltration <span class="hlt">pressure</span> distributions, such as the delayed peak, central peak, and advanced peak distributions, on the time of landslide initiation and the speed of landslide movement were compared and discussed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017AGUFM.T52C..02F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017AGUFM.T52C..02F"><span>The Rapid Formation of Localized Compaction Bands Under Hydrostatic Load Leading to <span class="hlt">Pore-pressure</span> Transients in Compacting Rocks</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Faulkner, D.; Leclere, H.; Bedford, J. D.; Behnsen, J.; Wheeler, J.</p> <p>2017-12-01</p> <p>Compaction of porous rocks can occur uniformly or within localized deformation bands. The formation of compaction bands and their effects on deformation behaviour are poorly understood. Porosity may be primary and compaction can occur with burial, or it can be produced by metamorphic reactions with a solid volume reduction, that can then undergo collapse. We report results from hydrostatic compaction experiments on porous bassanite (CaSO4.0.5H2O) aggregates. Gypsum (CaSO4.2H2O) is first dehydrated under low effective <span class="hlt">pressure</span>, 4 MPa, to produce a bassanite aggregate with a porosity of 27%. Compaction is induced by increasing confining <span class="hlt">pressure</span> at rates from 0.001 MPa/s to 0.02 MPa/s while the sample is maintained at a temperature of 115°C. At slow compaction rates, porosity collapse proceeds smoothly. At higher compaction rates, sudden increases in the <span class="hlt">pore</span>-fluid <span class="hlt">pressure</span> occur with a magnitude of 5 MPa. Microstructural investigations using X-ray microtomography and SEM observations show that randomly oriented localized compaction features occur in all samples, where the bulk porosity of 18% outside the band is reduced to 5% inside the band. Previous work on deformation bands has suggested that localized compactive features only form under an elevated differential stress and not under a hydrostatic stress state. The magnitude of the <span class="hlt">pore-pressure</span> pulses can be explained by the formation of compaction bands. The results indicate that the compaction bands can form by rapid (unstable) propagation across the sample above a critical strain rate, or quasi-statically at low compaction rates without <span class="hlt">pore</span>-fluid <span class="hlt">pressure</span> bursts. The absence of <span class="hlt">pore</span>-fluid <span class="hlt">pressure</span> bursts at slow compaction rates can be explained by viscous deformation of the bassanite aggregate around the tip of a propagating compaction band, relaxing stress, and promoting stable propagation. Conversely, at higher compaction rates, viscous deformation cannot relax the stress sufficiently and unstable</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016JGRF..121..415K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016JGRF..121..415K"><span>Effects of coarse grain size distribution and fine particle content on <span class="hlt">pore</span> fluid <span class="hlt">pressure</span> and shear behavior in experimental debris flows</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kaitna, Roland; Palucis, Marisa C.; Yohannes, Bereket; Hill, Kimberly M.; Dietrich, William E.</p> <p>2016-02-01</p> <p>Debris flows are typically a saturated mixture of poorly sorted particles and interstitial fluid, whose density and flow properties depend strongly on the presence of suspended fine sediment. Recent research suggests that grain size distribution (GSD) influences excess <span class="hlt">pore</span> <span class="hlt">pressures</span> (i.e., <span class="hlt">pressure</span> in excess of predicted hydrostatic <span class="hlt">pressure</span>), which in turn plays a governing role in debris flow behaviors. We report a series of controlled laboratory experiments in a 4 m diameter vertically rotating drum where the coarse particle size distribution and the content of fine particles were varied independently. We measured basal <span class="hlt">pore</span> fluid <span class="hlt">pressures</span>, <span class="hlt">pore</span> fluid <span class="hlt">pressure</span> profiles (using novel sensor probes), velocity profiles, and longitudinal profiles of the flow height. Excess <span class="hlt">pore</span> fluid <span class="hlt">pressure</span> was significant for mixtures with high fines fraction. Such flows exhibited lower values for their bulk flow resistance (as measured by surface slope of the flow), had damped fluctuations of normalized fluid <span class="hlt">pressure</span> and normal stress, and had velocity profiles where the shear was concentrated at the base of the flow. These effects were most pronounced in flows with a wide coarse GSD distribution. Sustained excess fluid <span class="hlt">pressure</span> occurred during flow and after cessation of motion. Various mechanisms may cause dilation and contraction of the flows, and we propose that the sustained excess fluid <span class="hlt">pressures</span> during flow and once the flow has stopped may arise from hindered particle settling and yield strength of the fluid, resulting in transfer of particle weight to the fluid. Thus, debris flow behavior may be strongly influenced by sustained excess fluid <span class="hlt">pressures</span> controlled by particle settling rates.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017EGUGA..1918143S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017EGUGA..1918143S"><span>Susceptibility of experimental faults to <span class="hlt">pore</span> <span class="hlt">pressure</span> increase: insights from load-controlled experiments on calcite-bearing rocks</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Spagnuolo, Elena; Violay, Marie; Nielsen, Stefan; Cornelio, Chiara; Di Toro, Giulio</p> <p>2017-04-01</p> <p>Fluid <span class="hlt">pressure</span> has been indicated as a major factor controlling natural (e.g., L'Aquila, Italy, 2009 Mw 6.3) and induced seismicity (e.g., Wilzetta, Oklahoma, 2011 Mw 5.7). Terzaghi's principle states that the effective normal stress is linearly reduced by a <span class="hlt">pore</span> <span class="hlt">pressure</span> (Pf) increase σeff=σn(1 - αPf), where the effective stress parameter α, may be related to the fraction of the fault area that is flooded. A value of α =1 is often used by default, with Pf shifting the Mohr circle towards lower normal effective stresses and anticipating failure on pre-existing faults. However, within a complex fault core of inhomogeneous permeability, α may vary in a yet poorly understood way. To shed light on this problem, we conducted experiments on calcite-bearing rock samples (Carrara marble) at room humidity conditions and in the presence of <span class="hlt">pore</span> fluids (drained conditions) using a rotary apparatus (SHIVA). A pre-cut fault is loaded by constant shear stress τ under constant normal stress σn=15 MPa until a target value corresponding roughly to the 80 % of the frictional fault strength. The <span class="hlt">pore</span> <span class="hlt">pressure</span> Pf is then raised with regular <span class="hlt">pressure</span> and time steps to induce fault instability. Assuming α=1 and a threshold for instability τp_eff=μp σeff, the experiments reveal that an increase of Pf does not necessarily induce an instability even when the effective strength threshold is largely surpassed (e.g., τp_eff=1.3 μpσeff). This result may indicate that the Pf increase did not instantly diffuse throughout the slip zone, but took a finite time to equilibrate with the external imposed <span class="hlt">pressure</span> increase due to finite permeability. Under our experimental conditions, a significant departure from α=1 is observed provided that the Pf step is shorter than about < 20s. We interpret this delay as indicative of the diffusion time (td), which is related to fluid penetration length l by l = √ κtd-, where κ is the hydraulic diffusivity on the fault plane. We show that a</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012AGUFMNH31B1602B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012AGUFMNH31B1602B"><span>Elucidating the mechanical effects of <span class="hlt">pore</span> water <span class="hlt">pressure</span> increase on the stability of unsaturated soil slopes</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Buscarnera, G.</p> <p>2012-12-01</p> <p>The increase of the <span class="hlt">pore</span> water <span class="hlt">pressure</span> due to rain infiltration can be a dominant component in the activation of slope failures. This paper shows an application of the theory of material stability to the triggering analysis of this important class of natural hazards. The goal is to identify the mechanisms through which the process of suction removal promotes the initiation of mechanical instabilities. The interplay between increase in <span class="hlt">pore</span> water <span class="hlt">pressure</span>, and failure mechanisms is investigated at material point level. In order to account for multiple failure mechanisms, the second-order work criterion is used and different stability indices are devised. The paper shows that the theory of material stability can assess the risk of shear failure and static liquefaction in both saturated and unsaturated contexts. It is shown that the combined use of an enhanced definition of second-order work for unsaturated porous media and a hydro-mechanical constitutive framework enables to retrieve bifurcation conditions for water-infiltration processes in unsaturated deposits. This finding discloses the importance of the coupling terms that incorporate the interaction between the solid skeleton and the <span class="hlt">pore</span> fluids. As a consequence, these theoretical results suggest that some material properties that are not directly associated with the shearing resistance (e.g., the potential for wetting compaction) can play an important role in the initiation of slope failures. According to the proposed interpretation, the process of <span class="hlt">pore</span> <span class="hlt">pressure</span> increase can be understood as a trigger of uncontrolled strains, which at material point level are reflected by the onset of bifurcation conditions.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2003EAEJA.....9385B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2003EAEJA.....9385B"><span>Integrated landslide monitoring: rainfalls, <span class="hlt">pore</span> water <span class="hlt">pressures</span> and surface movements</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Berti, M.; Casula, G.; Elmi, C.; Fabris, M.; Ghirotti, M.; Loddo, F.; Mora, P.; Pesci, A.; Simoni, A.</p> <p>2003-04-01</p> <p>Rainfall-induced landslides involving clay-rich soils are widely represented in the Apennines. They cover up to 30% of the slopes forming the relief constituted by chaotic clayey units and are typically subject to repeated reactivations of the movement which are often triggered by a series of discrete failures located in the upper part (headscarp). Failures and movement can then propagate downslope and reactivate the whole landslide deposit which displays a typical elongated body, limited depth and a fan-shaped toe as a result of successive slow earth-flow like movements. An experimental monitoring programme was designed and is currently operating on the Rocca Pitigliana landslide whose characteristics well represent the above described type of movements. Its last parossistic movement date back to 1999 and, since then, remedial works were realized on behalf of local authorities. They basically consist of surficial and deep drainage works located on the landslide body. Experimental activities focus on the main headscarp whose morphology and sub-surface water circulation scheme were unaffected by the interventions. The monitoring approach includes measuring rainfalls and <span class="hlt">pore-pressure</span> responses in both saturated and unsaturated soils. Surficial movements are continuously measured by means of GPS permanent stations and by wire extensometers which allow real time control of headscarp activity. Main aim of the monitoring activities is to provide experimental data, which can be used to test various existing hydrologic models and to identify triggering conditions. Since the ‘70s, many hydrologic models have been proposed to describe the <span class="hlt">pore</span> water <span class="hlt">pressure</span> distribution within the soil and its response to precipitation. The topic has recently drawn growing attention because of the recognized importance in landslide triggering but still experimental data are very much needed in order to obtain and validate capable predicting tools. This is mostly due to the multiple and</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ars.usda.gov/research/publications/publication/?seqNo115=289056','TEKTRAN'); return false;" href="http://www.ars.usda.gov/research/publications/publication/?seqNo115=289056"><span><span class="hlt">Pore</span>-water <span class="hlt">pressures</span> associated with clogging of soil pipes: Numerical analysis of laboratory experiments</span></a></p> <p><a target="_blank" href="https://www.ars.usda.gov/research/publications/find-a-publication/">USDA-ARS?s Scientific Manuscript database</a></p> <p></p> <p></p> <p>Clogging of soil pipes due to excessive internal erosion has been hypothesized to cause extreme erosion events such as landslides, debris flows, and gullies, but confirmation of this phenomenon has been lacking. Laboratory and field measurements have failed to measure <span class="hlt">pore</span> water <span class="hlt">pressures</span> within pip...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017AGUFMMR11A0298X','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017AGUFMMR11A0298X"><span>Multiscale <span class="hlt">Pore</span> Throat Network Reconstruction of Tight Porous Media Constrained by Mercury Intrusion Capillary <span class="hlt">Pressure</span> and Nuclear Magnetic Resonance Measurements</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Xu, R.; Prodanovic, M.</p> <p>2017-12-01</p> <p>Due to the low porosity and permeability of tight porous media, hydrocarbon productivity strongly depends on the <span class="hlt">pore</span> structure. Effective characterization of <span class="hlt">pore</span>/throat sizes and reconstruction of their connectivity in tight porous media remains challenging. Having a representative <span class="hlt">pore</span> throat network, however, is valuable for calculation of other petrophysical properties such as permeability, which is time-consuming and costly to obtain by experimental measurements. Due to a wide range of length scales encountered, a combination of experimental methods is usually required to obtain a comprehensive picture of the <span class="hlt">pore</span>-body and <span class="hlt">pore</span>-throat size distributions. In this work, we combine mercury intrusion capillary <span class="hlt">pressure</span> (MICP) and nuclear magnetic resonance (NMR) measurements by percolation theory to derive <span class="hlt">pore</span>-body size distribution, following the work by Daigle et al. (2015). However, in their work, the actual <span class="hlt">pore</span>-throat sizes and the distribution of coordination numbers are not well-defined. To compensate for that, we build a 3D unstructured two-scale <span class="hlt">pore</span> throat network model initialized by the measured porosity and the calculated <span class="hlt">pore</span>-body size distributions, with a tunable <span class="hlt">pore</span>-throat size and coordination number distribution, which we further determine by matching the capillary <span class="hlt">pressure</span> vs. saturation curve from MICP measurement, based on the fact that the mercury intrusion process is controlled by both the <span class="hlt">pore</span>/throat size distributions and the connectivity of the <span class="hlt">pore</span> system. We validate our model by characterizing several core samples from tight Middle East carbonate, and use the network model to predict the apparent permeability of the samples under single phase fluid flow condition. Results show that the permeability we get is in reasonable agreement with the Coreval experimental measurements. The <span class="hlt">pore</span> throat network we get can be used to further calculate relative permeability curves and simulate multiphase flow behavior, which will provide valuable</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015AGUFM.T21E2879M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AGUFM.T21E2879M"><span>Quaternary Sediment Accumulation in the Aleutian Trench: Implications for Dehydration Reaction Progress and <span class="hlt">Pore</span> <span class="hlt">Pressure</span> Development Offshore Alaska</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Meridth, L. N.; Screaton, E.; Jaeger, J. M.; James, S. R.; Villaseñor, T. G.</p> <p>2015-12-01</p> <p>Sediment inputs to subduction zones impart a significant control on diagenetic reaction progress, fluid production and <span class="hlt">pore</span> <span class="hlt">pressure</span> development and thus affect hydrologic and tectonic behavior during subduction. Intensified glaciation following the mid-Pleistocene transition increased sediment flux to the Gulf of Alaska. Rapid sediment accumulation (>1 km/my) in the Aleutian Trench increases overburden and should accelerate dehydration of hydrous sedimentary components by elevating temperatures in the incoming sediment column. These processes have the potential to generate fluid overpressures in the mud-dominated, low permeability sediments deposited on the incoming plate, offshore SE Alaska. Mineralogical analyses on incoming sediments from Deep Sea Drilling Project Leg 18 and Integrated Ocean Drilling Program Expedition 341 show that both smectite and Opal-A are present as hydrous mineral phases. A 1-D numerical model was developed to track dehydration reaction progress and <span class="hlt">pore</span> <span class="hlt">pressures</span> in the incoming sediment column from the abyssal plain to the Aleutian Trench. Simulated temperatures in the incoming column increase due to the insulating effect of trench sediments. As a result, trench sedimentation causes smectite dehydration to begin and Opal-A dehydration to nearly reach completion at the deformation front. Simulated excess <span class="hlt">pore</span> <span class="hlt">pressures</span> in the proto-decollement zone increase from nearly hydrostatic to almost half of lithostatic due to the rapid deposition of trench sediments. The 1-D modeling results were incorporated into a 2-D model that follows the underthrust column at the deformation front into the subduction zone. Simulated results of the 2-D flow model illustrate the effects of lateral flow on <span class="hlt">pore</span> <span class="hlt">pressure</span> distribution following subduction.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2003JGRB..108.2261S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2003JGRB..108.2261S"><span><span class="hlt">Pore</span> <span class="hlt">pressure</span> development and progressive dewatering in underthrust sediments at the Costa Rican subduction margin: Comparison with northern Barbados and Nankai</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Saffer, Demian M.</p> <p>2003-05-01</p> <p>At subduction zones, <span class="hlt">pore</span> <span class="hlt">pressure</span> affects fault strength, deformation style, structural development, and potentially the updip limit of seismogenic faulting behavior through its control on effective stress and consolidation state. Despite its importance for a wide range of subduction zone processes, few detailed measurements or estimates of <span class="hlt">pore</span> <span class="hlt">pressure</span> at subduction zones exist. In this paper, I combine logging-while-drilling (LWD) data, downhole physical properties data, and laboratory consolidation tests from the Costa Rican, Nankai, and Barbados subduction zones, to document the development and downsection variability of effective stress and <span class="hlt">pore</span> <span class="hlt">pressure</span> within underthrust sediments as they are progressively loaded by subduction. At Costa Rica, my results suggest that the lower portion of the underthrust section remains nearly undrained, whereas the upper portion is partially drained. An inferred minimum in effective stress developed within the section ˜1.5 km landward of the trench is consistent with core and seismic observations of faulting, and illustrates the important effects of heterogeneous drainage on structural development. Inferred <span class="hlt">pore</span> <span class="hlt">pressures</span> at the Nankai and northern Barbados subduction zones indicate nearly undrained conditions throughout the studied intervals, and are consistent with existing direct measurements and consolidation test results. Slower dewatering at Nankai and Barbados than at Costa Rica can be attributed to higher permeability and larger compressibility of near-surface sediments underthrust at Costa Rica. Results for the three margins indicate that the <span class="hlt">pore</span> <span class="hlt">pressure</span> ratio (λ) in poorly drained underthrust sediments should increase systematically with distance landward of the trench, and may vary with depth.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017AGUFMMR13B0321M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017AGUFMMR13B0321M"><span><span class="hlt">Pore</span> <span class="hlt">Pressure</span> and Field stress variation from Salt Water Injection; A case Study from Beaver Lodge Field in Williston Basin</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Mohammed, R. A.; Khatibi, S.</p> <p>2017-12-01</p> <p>One of the major concerns in producing from oil and gas reservoirs in North American Basins is the disposal of high salinity salt water. It is a misconception that Hydro frack triggers Earthquakes, but due to the high salinity and density of water being pumped to the formation that has <span class="hlt">pore</span> space of the rock already filled, which is not the case in Hydro-frack or Enhanced Oil Recovery in which fracturing fluid is pumped into empty <span class="hlt">pore</span> space of rocks in depleted reservoirs. A review on the Bakken history showed that the concerns related to induce seismicity has increased over time due to variations in <span class="hlt">Pore</span> <span class="hlt">pressure</span> and In-situ stress that have shown steep changes in the region over the time. In this study, we focused on <span class="hlt">Pore</span> <span class="hlt">pressure</span> and field Stress variations in lower Cretaceous Inyan Kara and Mississippian Devonian Bakken, Inyan Kara is the major source for class-II salt-water disposal in the basin. Salt-water disposal is the major cause for induced seismicity. A full field study was done on Beaver Lodge Field, which has many salt-water disposal wells Adjacent to Oil and Gas Wells. We analyzed formation properties, stresses, <span class="hlt">pore-pressure</span>, and fracture gradient profile in the field and. The constructed Mechanical Earth Model (MEM) revealed changes in <span class="hlt">pore</span> <span class="hlt">pressure</span> and stresses over time due to saltwater injection. Well drilled in the past were compared to recently drilled wells, which showed much stress variations. Safe mud weight Window of wells near proximity of injection wells was examined which showed many cases of wellbore instabilities. Results of this study will have tremendous impact in studying environmental issues and the future drilling and Fracking operations.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014AdWR...69...49Z','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014AdWR...69...49Z"><span>Computation of three-phase capillary entry <span class="hlt">pressures</span> and arc menisci configurations in <span class="hlt">pore</span> geometries from 2D rock images: A combinatorial approach</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Zhou, Yingfang; Helland, Johan Olav; Hatzignatiou, Dimitrios G.</p> <p>2014-07-01</p> <p>We present a semi-analytical, combinatorial approach to compute three-phase capillary entry <span class="hlt">pressures</span> for gas invasion into <span class="hlt">pore</span> throats with constant cross-sections of arbitrary shapes that are occupied by oil and/or water. For a specific set of three-phase capillary <span class="hlt">pressures</span>, geometrically allowed gas/oil, oil/water and gas/water arc menisci are determined by moving two circles in opposite directions along the <span class="hlt">pore</span>/solid boundary for each fluid pair such that the contact angle is defined at the front circular arcs. Intersections of the two circles determine the geometrically allowed arc menisci for each fluid pair. The resulting interfaces are combined systematically to allow for all geometrically possible three-phase configuration changes. The three-phase extension of the Mayer and Stowe - Princen method is adopted to calculate capillary entry <span class="hlt">pressures</span> for all determined configuration candidates, from which the most favorable gas invasion configuration is determined. The model is validated by comparing computed three-phase capillary entry <span class="hlt">pressures</span> and corresponding fluid configurations with analytical solutions in idealized triangular star-shaped <span class="hlt">pores</span>. It is demonstrated that the model accounts for all scenarios that have been analyzed previously in these shapes. Finally, three-phase capillary entry <span class="hlt">pressures</span> and associated fluid configurations are computed in throat cross-sections extracted from segmented SEM images of Bentheim sandstone. The computed gas/oil capillary entry <span class="hlt">pressures</span> account for the expected dependence of oil/water capillary <span class="hlt">pressure</span> in spreading and non-spreading fluid systems at the considered wetting conditions. Because these geometries are irregular and include constrictions, we introduce three-phase displacements that have not been identified previously in <span class="hlt">pore</span>-network models that are based on idealized <span class="hlt">pore</span> shapes. However, in the limited number of <span class="hlt">pore</span> geometries considered in this work, we find that the favorable displacements are</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/24199602','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/24199602"><span>Effects of setting under air <span class="hlt">pressure</span> on the number of surface <span class="hlt">pores</span> and irregularities of dental investment materials.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Tourah, Anita; Moshaverinia, Alireza; Chee, Winston W</p> <p>2014-02-01</p> <p>Surface roughness and irregularities are important properties of dental investment materials that can affect the fit of a restoration. Whether setting under air <span class="hlt">pressure</span> affects the surface irregularities of gypsum-bonded and phosphate-bonded investment materials is unknown. The purpose of this study was to investigate the effect of air <span class="hlt">pressure</span> on the <span class="hlt">pore</span> size and surface irregularities of investment materials immediately after pouring. Three dental investments, 1 gypsum-bonded investment and 2 phosphate-bonded investments, were investigated. They were vacuum mixed according to the manufacturers' recommendations, then poured into a ringless casting system. The prepared specimens were divided into 2 groups: 1 bench setting and the other placed in a <span class="hlt">pressure</span> pot at 172 kPa. After 45 minutes of setting, the rings were removed and the investments were cut at a right angle to the long axis with a diamond disk. The surfaces of the investments were steam cleaned, dried with an air spray, and observed with a stereomicroscope. A profilometer was used to evaluate the surface roughness (μm) of the castings. The number of surface <span class="hlt">pores</span> was counted for 8 specimens from each group and the means and standard deviations were reported. Two-way ANOVA was used to compare the data. Specimens that set under atmospheric air <span class="hlt">pressure</span> had a significantly higher number of <span class="hlt">pores</span> than specimens that set under increased <span class="hlt">pressure</span> (P<.05). No statistically significant differences for surface roughness were found (P=.078). Also, no significant difference was observed among the 3 different types of materials tested (P>.05). Specimens set under positive <span class="hlt">pressure</span> in a <span class="hlt">pressure</span> chamber presented fewer surface bubbles than specimens set under atmospheric <span class="hlt">pressure</span>. Positive <span class="hlt">pressure</span> is effective and, therefore, is recommended for both gypsum-bonded and phosphate-bonded investment materials. Copyright © 2014 Editorial Council for the Journal of Prosthetic Dentistry. Published by Mosby, Inc. All</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012AGUFM.T22A..06K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012AGUFM.T22A..06K"><span>10+ years of ACORK: Continuous <span class="hlt">pore</span> <span class="hlt">pressure</span> record from the decollement zone at Nankai Trough off Muroto</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kinoshita, M.; Davis, E. E.; Becker, K.; Miyazaki, J.; Hulme, S.; Mendrum, R.; Toki, T.; Wheat, C. G.; Kasaya, T.</p> <p>2012-12-01</p> <p><span class="hlt">Pore</span> <span class="hlt">pressure</span> and hydrological properties play key roles in governing coupling and slip behavior along the subducting plate interface. During the KR22-12 cruise, three dives were completed using ROV KAIKO onboard R/V KAIREI during Dec. 20-25, 2011, to retrieve <span class="hlt">pore</span> <span class="hlt">pressure</span> data and interstitial fluid samples from ACORKs at ODP Holes 808I and 1173B situated landward and seaward of the deformation front in the Nankai Trough off Cape Muroto. With 3-year-long and a 4-year-long new data records from Holes 808I and 1173B, respectively, we now have over 10-year-long continuous <span class="hlt">pressure</span> records since June 2001 at both sites. Data from most monitoring depths show systematic variations in average <span class="hlt">pressure</span>, and in formation <span class="hlt">pressure</span> response to seafloor tidal loading. In 2005 and 2009, we observed significant decrease in the amplitudes of <span class="hlt">pressure</span> response to semi-diurnal tidal loading at Hole 808I. Transient changes were observed at the time of several nearby earthquakes, including the 2011 Mar. 11 Tohoku earthquake, followed by long-lasting <span class="hlt">pressure</span> changes in both holes starting on Mar. 23, 2011. Gas-tight fluid sampling operations were successfully carried out from the hydraulic port attached to the swellable packer inserted within the ACORK head at Hole 808I. The swellable packer was set in order to isolate the décollement zone that lies roughly 20 m below the bottom of casing at 922 m below the seafloor. We observed shimmering water venting through the port, and the flow rate was measured using a ball-type flowmeter. Fluid samples looked muddy, probably as a result of staining from the casing steel. We believe that the packer seal at the ACORK head is set properly, although the <span class="hlt">pore</span> <span class="hlt">pressure</span> at 922 m does not seem to have increased up to 2011. Still, the observed fluid seepage suggests a significant amount of fluid evacuated from the décollement zone since ACORK installation, which may have changed its hydrogeological condition.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/biblio/5255811-effects-pore-pressure-mud-filtration-drilling-rates-permeable-sandstone','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/5255811-effects-pore-pressure-mud-filtration-drilling-rates-permeable-sandstone"><span>Effects of <span class="hlt">pore</span> <span class="hlt">pressure</span> and mud filtration on drilling rates in a permeable sandstone</span></a></p> <p><a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a></p> <p>Black, A.D.; DiBona, B.; Sandstrom, J.</p> <p>1983-10-01</p> <p>During laboratory drilling tests in a permeable sandstone, the effects of <span class="hlt">pore</span> <span class="hlt">pressure</span> and mud filtration on penetration rates were measured. Four water-base muds were used to drill four saturated sandstone samples. The drilling tests were conducted at constant borehole <span class="hlt">pressure</span> with different back <span class="hlt">pressures</span> maintained on the filtrate flowing from the bottom of the sandstone samples. Bit weight was also varied. Filtration rates were measured while drilling and with the bit off bottom and mud circulating. Penetration rates were found to be related to the difference between the filtration rates measured while drilling and circulating. There was no observedmore » correlation between standard API filtration measurements and penetration rate.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/pages/biblio/1158896-irreversible-xenon-insertion-small-pore-zeolite-moderate-pressures-temperatures','SCIGOV-DOEP'); return false;" href="https://www.osti.gov/pages/biblio/1158896-irreversible-xenon-insertion-small-pore-zeolite-moderate-pressures-temperatures"><span>Irreversible xenon insertion into a small-<span class="hlt">pore</span> zeolite at moderate <span class="hlt">pressures</span> and temperatures</span></a></p> <p><a target="_blank" href="http://www.osti.gov/pages">DOE PAGES</a></p> <p>Seoung, Donghoon; Cynn, Hyunchae; Park, Changyong; ...</p> <p>2014-09-01</p> <p><span class="hlt">Pressure</span> drastically alters the chemical and physical properties of materials and allows structural phase transitions and chemical reactions to occur that defy much of our understanding gained under ambient conditions. Particularly exciting is the high-<span class="hlt">pressure</span> chemistry of xenon, which is known to react with hydrogen and ice at high <span class="hlt">pressures</span> and form stable compounds. Here, we show that Ag 16Al 16Si 24O 8·16H 2O (Ag-natrolite) irreversibly inserts xenon into its micropores at 1.7 GPa and 250 °C, while Ag + is reduced to metallic Ag and possibly oxidized to Ag 2+. In contrast to krypton, xenon is retained within themore » <span class="hlt">pores</span> of this zeolite after <span class="hlt">pressure</span> release and requires heat to desorb. This irreversible insertion and trapping of xenon in Ag-natrolite under moderate conditions sheds new light on chemical reactions that could account for the xenon deficiency relative to argon observed in terrestrial and Martian atmospheres.« less</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_3");'>3</a></li> <li><a href="#" onclick='return showDiv("page_4");'>4</a></li> <li class="active"><span>5</span></li> <li><a href="#" onclick='return showDiv("page_6");'>6</a></li> <li><a href="#" onclick='return showDiv("page_7");'>7</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_5 --> <div id="page_6" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_4");'>4</a></li> <li><a href="#" onclick='return showDiv("page_5");'>5</a></li> <li class="active"><span>6</span></li> <li><a href="#" onclick='return showDiv("page_7");'>7</a></li> <li><a href="#" onclick='return showDiv("page_8");'>8</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="101"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013GGG....14.1454S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013GGG....14.1454S"><span>In situ stress and <span class="hlt">pore</span> <span class="hlt">pressure</span> in the Kumano Forearc Basin, offshore SW Honshu from downhole measurements during riser drilling</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Saffer, D. M.; Flemings, P. B.; Boutt, D.; Doan, M.-L.; Ito, T.; McNeill, L.; Byrne, T.; Conin, M.; Lin, W.; Kano, Y.; Araki, E.; Eguchi, N.; Toczko, S.</p> <p>2013-05-01</p> <p>situ stress and <span class="hlt">pore</span> <span class="hlt">pressure</span> are key parameters governing rock deformation, yet direct measurements of these quantities are rare. During Integrated Ocean Drilling Program (IODP) Expedition #319, we drilled through a forearc basin at the Nankai subduction zone and into the underlying accretionary prism. We used the Modular Formation Dynamics Tester tool (MDT) for the first time in IODP to measure in situ minimum stress, <span class="hlt">pore</span> <span class="hlt">pressure</span>, and permeability at 11 depths between 729.9 and 1533.9 mbsf. Leak-off testing at 708.6 mbsf conducted as part of drilling operations provided a second measurement of minimum stress. The MDT campaign included nine single-probe (SP) tests to measure permeability and in situ <span class="hlt">pore</span> <span class="hlt">pressure</span> and two dual-packer (DP) tests to measure minimum principal stress. Permeabilities defined from the SP tests range from 6.53 × 10-17 to 4.23 × 10-14 m2. <span class="hlt">Pore</span> fluid <span class="hlt">pressures</span> are near hydrostatic throughout the section despite rapid sedimentation. This is consistent with the measured hydraulic diffusivity of the sediments and suggests that the forearc basin should not trap overpressures within the upper plate of the subduction zone. Minimum principal stresses are consistently lower than the vertical stress. We estimate the maximum horizontal stress from wellbore failures at the leak-off test and shallow MDT DP test depths. The results indicate a normal or strike-slip stress regime, consistent with the observation of abundant active normal faults in the seaward-most part of the basin, and a general decrease in fault activity in the vicinity of Site C0009.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/28436177','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/28436177"><span>Limited evidence of <span class="hlt">abnormal</span> intra-colonic <span class="hlt">pressure</span> profiles in diverticular disease - a systematic review.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Jaung, R; Robertson, J; O'Grady, G; Milne, T; Rowbotham, D; Bissett, I P</p> <p>2017-06-01</p> <p><span class="hlt">Abnormal</span> colonic <span class="hlt">pressure</span> profiles and high intraluminal <span class="hlt">pressures</span> are postulated to contribute to the formation of sigmoid colon diverticulosis and the pathophysiology of diverticular disease. This study aimed to review evidence for <span class="hlt">abnormal</span> colonic <span class="hlt">pressure</span> profiles in diverticulosis. All published studies investigating colonic <span class="hlt">pressure</span> in patients with diverticulosis were searched in three databases (Medline, Embase, Scopus). No language restrictions were applied. Any manometry studies in which patients with diverticulosis were compared with controls were included. The Newcastle-Ottawa Quality Assessment Scale (NOS) for case-control studies was used as a measure of risk of bias. A cut-off of five or more points on the NOS (fair quality in terms of risk of bias) was chosen for inclusion in the meta-analysis. Ten studies (published 1962-2005) met the inclusion criteria. The studies followed a wide variety of protocols and all used low-resolution manometry (sensor spacing range 7.5-15 cm). Six studies compared intra-sigmoid <span class="hlt">pressure</span>, with five of six showing higher <span class="hlt">pressure</span> in diverticulosis vs controls, but only two reached statistical significance. A meta-analysis was not performed as only two studies were above the cut-off and these did not have comparable outcomes. This systematic review of manometry data shows that evidence for <span class="hlt">abnormal</span> <span class="hlt">pressure</span> in the sigmoid colon in patients with diverticulosis is weak. Existing studies utilized inconsistent methodology, showed heterogeneous results and are of limited quality. Higher quality studies using modern manometric techniques and standardized reporting methods are needed to clarify the role of colonic <span class="hlt">pressure</span> in diverticulosis. Colorectal Disease © 2017 The Association of Coloproctology of Great Britain and Ireland.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/28114035','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/28114035"><span>Battery-Free Smart Sock for <span class="hlt">Abnormal</span> Relative Plantar <span class="hlt">Pressure</span> Monitoring.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Lin, Xiaoyou; Seet, Boon-Chong</p> <p>2017-04-01</p> <p>This paper presents a new design of a wearable plantar <span class="hlt">pressure</span> monitoring system in the form of a smart sock for sensing <span class="hlt">abnormal</span> relative <span class="hlt">pressure</span> changes. One advantage of this approach is that with a battery-free design, this system can be powered solely by radio frequency (RF) energy harvested from a radio frequency identification (RFID) reader unit hosted on a smartphone of the wearer. At the same time, this RFID reader can read foot <span class="hlt">pressure</span> values from an embedded sensor-tag in the sock. A <span class="hlt">pressure</span> sensing matrix made of conductive fabric and flexible piezo-resistive material is integrated into the sock during the knitting process. Sensed foot <span class="hlt">pressures</span> are digitized and stored in the memory of a sensor-tag, thus allowing relative foot <span class="hlt">pressure</span> values to be tracked. The control unit of the smart sock is assembled on a flexible printed circuit board (FPC) that can be strapped to the lower limb and detached easily when it is not in use. Experiments show that the system can operate reliably in both tasks of RF energy harvesting and <span class="hlt">pressure</span> measurement.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011AGUFM.T33F2490K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011AGUFM.T33F2490K"><span>Modeling of Permeability Structure Using <span class="hlt">Pore</span> <span class="hlt">Pressure</span> and Borehole Strain Monitoring</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kano, Y.; Ito, H.</p> <p>2011-12-01</p> <p>Hydraulic or transport property, especially permeability, of the rock affect the behavior of the fault during earthquake rupture and also interseismic period. The methods to determine permeability underground are hydraulic test utilizing borehole and packer or core measurement in laboratory. Another way to know the permeability around a borehole is to examine responses of <span class="hlt">pore</span> <span class="hlt">pressure</span> to natural loading such as barometric <span class="hlt">pressure</span> change at surface or earth tides. Using response to natural deformation is conventional method for water resource research. The scale of measurement is different among in-situ hydraulic test, response method, and core measurement. It is not clear that the relationship between permeability values form each method for an inhomogeneous medium such as a fault zone. Supposing the measurement of the response to natural loading, we made a model calculation of permeability structure around a fault zone. The model is 2 dimensional and constructed with vertical high-permeability layer in uniform low-permeability zone. We assume the upper and lower boundaries are drained and no-flow condition. We calculated the flow and deformation of the model for step and cyclic loading by numerically solving a two-dimensional diffusion equation. The model calculation shows that the width of the high-permeability zone and contrast of the permeability between high- and low- permeability zones control the contribution of the low-permeability zone. We made a calculation with combinations of permeability and fault width to evaluate the sensitivity of the parameters to in-situ measurement of permeability. We applied the model calculation to the field results of in-situ packer test, and natural response of water level and strain monitoring carried out in the Kamioka mine. The model calculation shows that knowledge of permeability in host rock is also important to obtain permeability of fault zone itself. The model calculations help to design long-term <span class="hlt">pore</span> <span class="hlt">pressure</span></p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012AGUFM.T23G..02K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012AGUFM.T23G..02K"><span>Quantification of in situ <span class="hlt">pore</span> <span class="hlt">pressure</span> and stress in regions of low frequency earthquakes and anomalously low seismic velocity at the Nankai Trough</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kitajima, H.; Saffer, D. M.</p> <p>2012-12-01</p> <p>Recent seismic reflection and ocean bottom seismometer (OBS) studies reveal broad regions of low seismic velocity along the megathrust plate boundary of the Nankai subduction zone offshore SW Japan. These low velocity zones (LVZ's) extend to ~55 km from the trench, corresponding to depths of >~10 km below sea floor. Elevated <span class="hlt">pore</span> <span class="hlt">pressure</span> has been invoked as one potential cause of both the LVZ's and very low frequency earthquakes (VLFE) in the outer forearc. Here, we estimate the in-situ <span class="hlt">pore</span> fluid <span class="hlt">pressure</span> and stress state within these LVZ's by combining P-wave velocities (Vp) obtained from seismic reflection and OBS data with well-constrained empirical relations between (1) P-wave velocity and porosity; and (2) porosity and effective mean and differential stresses, defined by triaxial deformation tests on drill core samples of the incoming oceanic sediment. We used cores of Lower Shikoku Basin (LSB) hemipelagic mudstone (322-C0011B-19R-5, initial porosity of 43%), and Middle Shikoku Basin (MSB) tuffaceous sandstone (333-C0011D-51X-2, initial porosity of 46%) that have been recovered from IODP Nankai Trough Seismogenic Zone Experiment (NanTroSEIZE) Site C0011 (~20 km seaward from the deformation front). Samples were loaded under a range of different stress paths including isotropic loading, triaxial compression, and triaxial extension. During the tests, all <span class="hlt">pressures</span>, axial displacement, and <span class="hlt">pore</span> volume change were continuously monitored; and ultrasonic velocity and permeability were measured at regular intervals. The relationship between Vp and porosity for LSB mudstone is independent of stress path, and is well fit by an empirical function derived by Hoffman and Tobin [2004] for LSB sediments sampled by drilling along Muroto transect, located ~150 km southwest of the NanTroSEIZE study area. The MSB sandstone exhibits slightly higher P-wave velocity than LSB mudstone at a given porosity. Based on our experimental results, and assuming that the sediments in the</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3863552','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3863552"><span><span class="hlt">Pore</span> Structure and Limit <span class="hlt">Pressure</span> of Gas Slippage Effect in Tight Sandstone</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>You, Lijun; Xue, Kunlin; Kang, Yili; Liao, Yi</p> <p>2013-01-01</p> <p>Gas slip effect is an important mechanism that the gas flow is different from liquid flow in porous media. It is generally considered that the lower the permeability in porous media is, the more severe slip effect of gas flow will be. We design and then carry out experiments with the increase of backpressure at the outlet of the core samples based on the definition of gas slip effect and in view of different levels of permeability of tight sandstone reservoir. This study inspects a limit <span class="hlt">pressure</span> of the gas slip effect in tight sandstones and analyzes the characteristic parameter of capillary <span class="hlt">pressure</span> curves. The experimental results indicate that gas slip effect can be eliminated when the backpressure reaches a limit <span class="hlt">pressure</span>. When the backpressure exceeds the limit <span class="hlt">pressure</span>, the measured gas permeability is a relatively stable value whose range is less than 3% for a given core sample. It is also found that the limit <span class="hlt">pressure</span> increases with the decreasing in permeability and has close relation with <span class="hlt">pore</span> structure of the core samples. The results have an important influence on correlation study on gas flow in porous medium, and are beneficial to reduce the workload of laboratory experiment. PMID:24379747</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/12703693','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/12703693"><span>Acoustic and mechanical response of reservoir rocks under variable saturation and effective <span class="hlt">pressure</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Ravazzoli, C L; Santos, J E; Carcione, J M</p> <p>2003-04-01</p> <p>We investigate the acoustic and mechanical properties of a reservoir sandstone saturated by two immiscible hydrocarbon fluids, under different saturations and <span class="hlt">pressure</span> conditions. The modeling of static and dynamic deformation processes in porous rocks saturated by immiscible fluids depends on many parameters such as, for instance, porosity, permeability, <span class="hlt">pore</span> fluid, fluid saturation, fluid <span class="hlt">pressures</span>, capillary <span class="hlt">pressure</span>, and effective stress. We use a formulation based on an extension of Biot's theory, which allows us to compute the coefficients of the stress-strain relations and the equations of motion in terms of the properties of the single phases at the in situ conditions. The dry-rock moduli are obtained from laboratory measurements for variable confining <span class="hlt">pressures</span>. We obtain the bulk compressibilities, the effective <span class="hlt">pressure</span>, and the ultrasonic phase velocities and quality factors for different saturations and <span class="hlt">pore</span>-fluid <span class="hlt">pressures</span> ranging from normal to <span class="hlt">abnormally</span> high values. The objective is to relate the seismic and ultrasonic velocity and attenuation to the microstructural properties and <span class="hlt">pressure</span> conditions of the reservoir. The problem has an application in the field of seismic exploration for predicting <span class="hlt">pore</span>-fluid <span class="hlt">pressures</span> and saturation regimes.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010HESSD...7.6491D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010HESSD...7.6491D"><span>Big and small: menisci in soil <span class="hlt">pores</span> affect water <span class="hlt">pressures</span>, dynamics of groundwater levels, and catchment-scale average matric potentials</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>de Rooij, G. H.</p> <p>2010-09-01</p> <p>Soil water is confined behind the menisci of its water-air interface. Catchment-scale fluxes (groundwater recharge, evaporation, transpiration, precipitation, etc.) affect the matric potential, and thereby the interface curvature and the configuration of the phases. In turn, these affect the fluxes (except precipitation), creating feedbacks between <span class="hlt">pore</span>-scale and catchment-scale processes. Tracking <span class="hlt">pore</span>-scale processes beyond the Darcy scale is not feasible. Instead, for a simplified system based on the classical Darcy's Law and Laplace-Young Law we i) clarify how menisci transfer <span class="hlt">pressure</span> from the atmosphere to the soil water, ii) examine large-scale phenomena arising from <span class="hlt">pore</span>-scale processes, and iii) analyze the relationship between average meniscus curvature and average matric potential. In stagnant water, changing the gravitational potential or the curvature of the air-water interface changes the <span class="hlt">pressure</span> throughout the water. Adding small amounts of water can thus profoundly affect water <span class="hlt">pressures</span> in a much larger volume. The <span class="hlt">pressure</span>-regulating effect of the interface curvature showcases the meniscus as a <span class="hlt">pressure</span> port that transfers the atmospheric <span class="hlt">pressure</span> to the water with an offset directly proportional to its curvature. This property causes an extremely rapid rise of phreatic levels in soils once the capillary fringe extends to the soil surface and the menisci flatten. For large bodies of subsurface water, the curvature and vertical position of any meniscus quantify the uniform hydraulic potential under hydrostatic equilibrium. During unit-gradient flow, the matric potential corresponding to the mean curvature of the menisci should provide a good approximation of the intrinsic phase average of the matric potential.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2009AGUFMNH34A..07S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2009AGUFMNH34A..07S"><span>Stress and <span class="hlt">Pore</span> <span class="hlt">Pressure</span> Measurement in IODP Riser Drilling: An Example from Expedition 319, Kumano Basin offshore SW Honshu, Japan</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Saffer, D. M.; McNeill, L. C.; Byrne, T. B.; Araki, E.; Flemings, P. B.; Conin, M.; Eguchi, N. O.; Takahashi, K.; Toczko, S.; Boutt, D. F.; Doan, M.; Kano, Y.; Ito, T.; Lin, W.</p> <p>2009-12-01</p> <p>In summer 2009, Integrated Ocean Drilling Program (IODP) Expedition 319 drilled a 1600 m deep riser borehole (Site C0009) in the Kumano Basin offshore SW Japan, to investigate the properties, structure and state of stress in the hanging wall above the subduction plate boundary. The first riser-based scientific drilling in IODP history allowed us to make several new scientific measurements including in situ stress magnitude, <span class="hlt">pore</span> <span class="hlt">pressure</span> and permeability using the Modular Formation Dynamics Tester (MDT) wireline tool, and measurement of minimum stress magnitude from Leak-off Tests (LOT). In addition, continuous monitoring of mud weight, mud gas, annular <span class="hlt">pressure</span>, and mud losses provided data to constrain formation <span class="hlt">pore</span> fluid <span class="hlt">pressure</span> and stress. At Site C0009, we conducted 2 LOTs below a casing shoe at 708.6 m depth and 11 successful MDT measurements, including 9 single probe tests to measure <span class="hlt">pore</span> <span class="hlt">pressure</span> and fluid mobility and 2 dual packer tests: 1 to measure permeability by a drawdown test, and 1 to measure in situ stress. Measured <span class="hlt">pore</span> <span class="hlt">pressures</span> are approximately hydrostatic to 1463.7 m depth. We observed only minor gas shows when drilling ahead (as in-place methane was liberated from the rock at the bit) but little or no gas during pipe connections. This indicates that the borehole mud <span class="hlt">pressure</span> exceeded the formation <span class="hlt">pore</span> <span class="hlt">pressure</span>, and is consistent with the MDT measurements. Permeabilities range from ~10-16 m2 - 10-14 m2, and the observed variation is consistent with lithologic changes defined in gamma ray logs. The MDT measurement at 874.3 mbsf and the LOT at 708.6 m yield values for the least principal stress of 34.8 MPa and 30.2 MPa, respectively. Both are less than the vertical stress (Sv) computed from density logs. Partial mud circulation losses occurred when the borehole mud <span class="hlt">pressure</span> exceeded the leak-off stress measured at the base of the casing shoe; this provides an additional indirect constraint on Shmin magnitude. Mud <span class="hlt">pressure</span> slightly in excess</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011JSCGE..67..464Y','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011JSCGE..67..464Y"><span>MONITORING OF <span class="hlt">PORE</span> WATER <span class="hlt">PRESSURE</span> AND WATER CONTENT AROUND A HORIZONTAL DRIFT THROUGH EXCAVATION - MEASUREMENT AT THE 140m GALLERY IN THE HORONOBE URL -</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Yabuuchi, Satoshi; Kunimaru, Takanori; Kishi, Atsuyasu; Komatsu, Mitsuru</p> <p></p> <p>Japan Atomic Energy Agency has been conducting the Horonobe Underground Research Laboratory (URL) project in Horonobe, Hokkaido, as a part of the research and development program on geological disposal of high-level radioactive waste. <span class="hlt">Pore</span> water <span class="hlt">pressure</span> and water content around a horizontal drift in the URL have been monitored for over 18 months since before the drift excavation was started. During the drift excavation, both <span class="hlt">pore</span> water <span class="hlt">pressure</span> and water content were decreasing. <span class="hlt">Pore</span> water <span class="hlt">pressure</span> has been still positive though it continued to decrease with its gradient gradually smaller after excavation, while water content turned to increase about 6 months after the completion of the excavation. It turned to fall again about 5 months later. An unsaturated zone containing gases which were dissolved in groundwater may have been formed around the horizontal drift.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010EGUGA..1210970R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010EGUGA..1210970R"><span><span class="hlt">Pore</span> water <span class="hlt">pressure</span> variations in Subpermafrost groundwater : Numerical modeling compared with experimental modeling</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Rivière, Agnès.; Goncalves, Julio; Jost, Anne; Font, Marianne</p> <p>2010-05-01</p> <p>Development and degradation of permafrost directly affect numerous hydrogeological processes such as thermal regime, exchange between river and groundwater, groundwater flows patterns and groundwater recharge (Michel, 1994). Groundwater in permafrost area is subdivided into two zones: suprapermafrost and subpermafrost which are separated by permafrost. As a result of the volumetric expansion of water upon freezing and assuming ice lenses and frost heave do not form freezing in a saturated aquifer, the progressive formation of permafrost leads to the <span class="hlt">pressurization</span> of the subpermafrost groundwater (Wang, 2006). Therefore disappearance or aggradation of permafrost modifies the confined or unconfined state of subpermafrost groundwater. Our study focuses on modifications of <span class="hlt">pore</span> water <span class="hlt">pressure</span> of subpermafrost groundwater which could appear during thawing and freezing of soil. Numerical simulation allows elucidation of some of these processes. Our numerical model accounts for phase changes for coupled heat transport and variably saturated flow involving cycles of freezing and thawing. The flow model is a combination of a one-dimensional channel flow model which uses Manning-Strickler equation and a two-dimensional vertically groundwater flow model using Richards equation. Numerical simulation of heat transport consisted in a two dimensional model accounting for the effects of latent heat of phase change of water associated with melting/freezing cycles which incorporated the advection-diffusion equation describing heat-transfer in porous media. The change of hydraulic conductivity and thermal conductivity are considered by our numerical model. The model was evaluated by comparing predictions with data from laboratory freezing experiments. Experimental design was undertaken at the Laboratory M2C (Univesité de Caen-Basse Normandie, CNRS, France). The device consisted of a Plexiglas box insulated on all sides except on the top. Precipitation and ambient temperature are</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/20033046','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/20033046"><span>Tremor-tide correlations and near-lithostatic <span class="hlt">pore</span> <span class="hlt">pressure</span> on the deep San Andreas fault.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Thomas, Amanda M; Nadeau, Robert M; Bürgmann, Roland</p> <p>2009-12-24</p> <p>Since its initial discovery nearly a decade ago, non-volcanic tremor has provided information about a region of the Earth that was previously thought incapable of generating seismic radiation. A thorough explanation of the geologic process responsible for tremor generation has, however, yet to be determined. Owing to their location at the plate interface, temporal correlation with geodetically measured slow-slip events and dominant shear wave energy, tremor observations in southwest Japan have been interpreted as a superposition of many low-frequency earthquakes that represent slip on a fault surface. Fluids may also be fundamental to the failure process in subduction zone environments, as teleseismic and tidal modulation of tremor in Cascadia and Japan and high Poisson ratios in both source regions are indicative of <span class="hlt">pressurized</span> <span class="hlt">pore</span> fluids. Here we identify a robust correlation between extremely small, tidally induced shear stress parallel to the San Andreas fault and non-volcanic tremor activity near Parkfield, California. We suggest that this tremor represents shear failure on a critically stressed fault in the presence of near-lithostatic <span class="hlt">pore</span> <span class="hlt">pressure</span>. There are a number of similarities between tremor in subduction zone environments, such as Cascadia and Japan, and tremor on the deep San Andreas transform, suggesting that the results presented here may also be applicable in other tectonic settings.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015AGUFMNH41C1835C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AGUFMNH41C1835C"><span>First-order Probabilistic Analysis of the Effects of Heterogeneity on <span class="hlt">Pore</span>-water <span class="hlt">Pressure</span> in a Hillslope</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Cai, J.; Yan, E.; Yeh, T. C. J.</p> <p>2015-12-01</p> <p><span class="hlt">Pore</span>-water <span class="hlt">pressure</span> in a hillslope is a critical control of its stability. The main objective of this paper is to introduce a first-order moment analysis to investigate the <span class="hlt">pressure</span> head variability within a hypothetical hillslope, induced by steady rainfall infiltration. This approach accounts for the uncertainties and spatial variation of the hydraulic conductivity, and is based on a first-order Taylor approximation of <span class="hlt">pressure</span> perturbations calculated by a variably saturated, finite element flow model. Using this approach, the effects of variance (σ2lnKs) and spatial structure anisotropy (λh/λv) of natural logarithm of saturated hydraulic conductivity, and normalized vertical infiltration flux (q/ks) on the hillslope <span class="hlt">pore</span>-water <span class="hlt">pressure</span> are evaluated. We found that the responses of <span class="hlt">pressure</span> head variability (σ2p) are quite different between unsaturated region and saturated region divided by the phreatic surface. Above the phreatic surface, a higher variability in <span class="hlt">pressure</span> head is obtained from a higher σ2lnKs, a higher λh/λv and a smaller q/ks; while below the phreatic surface, a higher σ2lnKs, a lower λh/λv or a larger q/ks would lead to a higher variability in <span class="hlt">pressure</span> head, and greater range of fluctuation of the phreatic surface within the hillslope. σ2lnKs has greatest impact on σ2p within the slope and λh/λv has smallest impact. All three variables have greater influence on maximum σ2p within the saturated region below the phreatic surface than that within the unsaturated region above the phreatic surface. The results obtained from this study are useful to understand the influence of hydraulic conductivity variations on slope seepage and stability under different slope conditions and material spatial distributions.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/biblio/6278791-quantification-abnormal-intracranial-pressure-waves-isotope-cisternography-diagnosis-occult-communicating-hydrocephalus','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/6278791-quantification-abnormal-intracranial-pressure-waves-isotope-cisternography-diagnosis-occult-communicating-hydrocephalus"><span>Quantification of <span class="hlt">abnormal</span> intracranial <span class="hlt">pressure</span> waves and isotope cisternography for diagnosis of occult communicating hydrocephalus</span></a></p> <p><a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a></p> <p>Cardoso, E.R.; Piatek, D.; Del Bigio, M.R.</p> <p>1989-01-01</p> <p>Nineteen consecutive patients with suspected occult communicating hydrocephalus were investigated by means of clinical evaluation, neuropsychological testing, isotope cisternography, computed tomography scanning, and continuous intracranial <span class="hlt">pressure</span> monitoring. Semi-quantitative grading systems were used in the evaluation of the clinical, neuropsychological, and cisternographic assessments. Clinical examination, neuropsychological testing, and computed tomography scanning were repeated 3 months after ventriculoperitoneal shunting. All patients showed <span class="hlt">abnormal</span> intracranial <span class="hlt">pressure</span> waves and all improved after shunting. There was close correlation between number, peak, and pulse <span class="hlt">pressures</span> of B waves and the mean intracranial <span class="hlt">pressure</span>. However, quantification of B waves by means of number, frequency, and amplitude didmore » not help in predicting the degree of clinical improvement postshunting. The most sensitive predictor of favorable response to shunting was enlargement of the temporal horns on computed tomography scan. Furthermore, the size of temporal horns correlated with mean intracranial <span class="hlt">pressure</span>. There was no correlation between <span class="hlt">abnormalities</span> on isotope cisternography and clinical improvement.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013AGUFM.T31G2598Z','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013AGUFM.T31G2598Z"><span>Long Term Observations of Subsurface <span class="hlt">Pore</span> <span class="hlt">Pressure</span> in the Kumano Basin and Upper Accretionary Wedge along the NanTroSIEZE Transect, offshore Japan: Signals from the 2011 Tohoku Earthquake</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Zhang, Y.; Saffer, D. M.</p> <p>2013-12-01</p> <p>Subsurface <span class="hlt">pore</span> <span class="hlt">pressure</span> as a sensitive measure of strain and formation properties has provided insights into the wide range of fault slip behaviors, contributing to the understanding of fault and earthquake mechanics. <span class="hlt">Pore</span> <span class="hlt">pressures</span> from off shore borehole observatory are especially important, as 1) they are the only detectable signals of small and slow events; 2) they provide our only access to the outer forearc, where the tsunami hazards are triggered by the fault slip. As part of the Nankai Trough Seismogenic Zone Experiment (NanTroSEIZE) a suite of borehole sensors were installed as part of a long-term borehole observatory at IODP Site C0002, during IODP Expedition # 332 in December of 2010. The observatory includes a broadband seismometer, short period geophones, a volumetric strainmeter, temperature sensors, an accelerometer, and formation <span class="hlt">pore</span> <span class="hlt">pressure</span> monitoring at two depths: one in the mudstones of the Kumano Basin in an interval spanning 757-780 meters below seafloor (mbsf), and a second in the uppermost accretionary wedge in an interval from 937 - 980 mbsf. Here, we report on <span class="hlt">pore</span> <span class="hlt">pressure</span> records acquired at a sampling frequency of 1/60 Hz, spanning the period from December 2010 to January 2013, which were recovered in early 2013. We observe a clear hydraulic signal from March 11, 2011 Tohoku earthquake and aftershocks, including both dynamic <span class="hlt">pore</span> <span class="hlt">pressure</span> changes during passage of surface waves and shifts in formation <span class="hlt">pressure</span> following the event. <span class="hlt">Pressure</span> exhibit an increase of ~3 kPa in the upper sediment screened interval following the earthquake, and decrease by ~5 kPa in the accretionary prism interval. Both of the offset changes persist through the end of the data recording. These <span class="hlt">pore</span> <span class="hlt">pressure</span> changes may reflect static stress changes from the earthquake, or local site effects related to shaking. We also observe a clear increase in formation <span class="hlt">pore</span> <span class="hlt">pressures</span> associated with drilling operations at nearby holes in November and December 2012. These</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/biblio/6323045-effects-pore-pressure-mud-filtration-drilling-rates-permeable-sandstone','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/6323045-effects-pore-pressure-mud-filtration-drilling-rates-permeable-sandstone"><span>Effects of <span class="hlt">pore</span> <span class="hlt">pressure</span> and mud filtration on drilling rates in a permeable sandstone</span></a></p> <p><a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a></p> <p>Black, A.D.; Dearing, H.L.; DiBona, B.G.</p> <p>1985-09-01</p> <p>During laboratory drilling tests in a permeable sandstone, the effects of <span class="hlt">pore</span> <span class="hlt">pressure</span> and mud filtration on penetration rates were measured. Four water-based muds were used to drill four saturated sandstone samples. The drilling tests were conducted at constant borehole <span class="hlt">pressure</span> while different backpressures were maintained on the filtrate flowing from the bottom of the sandstone samples. Bit weight was varied also. Filtration rates were measured while circulating mud during drilling and with the bit off bottom. Penetration rates were found to be related qualitatively to the difference between the filtration rates measured while drilling and circulating. There was nomore » observed correlation between standard API filtration measurements and penetration rate.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://pubs.er.usgs.gov/publication/70196642','USGSPUBS'); return false;" href="https://pubs.er.usgs.gov/publication/70196642"><span>Numerical models of <span class="hlt">pore</span> <span class="hlt">pressure</span> and stress changes along basement faults due to wastewater injection: Applications to the 2014 Milan, Kansas Earthquake</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Hearn, Elizabeth H.; Koltermann, Christine; Rubinstein, Justin R.</p> <p>2018-01-01</p> <p>We have developed groundwater flow models to explore the possible relationship between wastewater injection and the 12 November 2014 Mw 4.8 Milan, Kansas earthquake. We calculate <span class="hlt">pore</span> <span class="hlt">pressure</span> increases in the uppermost crust using a suite of models in which hydraulic properties of the Arbuckle Formation and the Milan earthquake fault zone, the Milan earthquake hypocenter depth, and fault zone geometry are varied. Given pre‐earthquake injection volumes and reasonable hydrogeologic properties, significantly increasing <span class="hlt">pore</span> <span class="hlt">pressure</span> at the Milan hypocenter requires that most flow occur through a conductive channel (i.e., the lower Arbuckle and the fault zone) rather than a conductive 3‐D volume. For a range of reasonable lower Arbuckle and fault zone hydraulic parameters, the modeled <span class="hlt">pore</span> <span class="hlt">pressure</span> increase at the Milan hypocenter exceeds a minimum triggering threshold of 0.01 MPa at the time of the earthquake. Critical factors include injection into the base of the Arbuckle Formation and proximity of the injection point to a narrow fault damage zone or conductive fracture in the pre‐Cambrian basement with a hydraulic diffusivity of about 3–30 m2/s. The maximum <span class="hlt">pore</span> <span class="hlt">pressure</span> increase we obtain at the Milan hypocenter before the earthquake is 0.06 MPa. This suggests that the Milan earthquake occurred on a fault segment that was critically stressed prior to significant wastewater injection in the area. Given continued wastewater injection into the upper Arbuckle in the Milan region, assessment of the middle Arbuckle as a hydraulic barrier remains an important research priority.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018PApGe.tmp.1320S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018PApGe.tmp.1320S"><span>Dynamic Stability of the Rate, State, Temperature, and <span class="hlt">Pore</span> <span class="hlt">Pressure</span> Friction Model at a Rock Interface</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Sinha, Nitish; Singh, Arun K.; Singh, Trilok N.</p> <p>2018-05-01</p> <p>In this article, we study numerically the dynamic stability of the rate, state, temperature, and <span class="hlt">pore</span> <span class="hlt">pressure</span> friction (RSTPF) model at a rock interface using standard spring-mass sliding system. This particular friction model is a basically modified form of the previously studied friction model namely the rate, state, and temperature friction (RSTF). The RSTPF takes into account the role of thermal <span class="hlt">pressurization</span> including dilatancy and permeability of the <span class="hlt">pore</span> fluid due to shear heating at the slip interface. The linear stability analysis shows that the critical stiffness, at which the sliding becomes stable to unstable or vice versa, increases with the coefficient of thermal <span class="hlt">pressurization</span>. Critical stiffness, on the other hand, remains constant for small values of either dilatancy factor or hydraulic diffusivity, but the same decreases as their values are increased further from dilatancy factor (˜ 10^{ - 4} ) and hydraulic diffusivity (˜ 10^{ - 9} {m}2 {s}^{ - 1} ) . Moreover, steady-state friction is independent of the coefficient of thermal <span class="hlt">pressurization</span>, hydraulic diffusivity, and dilatancy factor. The proposed model is also used for predicting time of failure of a creeping interface of a rock slope under the constant gravitational force. It is observed that time of failure decreases with increase in coefficient of thermal <span class="hlt">pressurization</span> and hydraulic diffusivity, but the dilatancy factor delays the failure of the rock fault under the condition of heat accumulation at the creeping interface. Moreover, stiffness of the rock-mass also stabilizes the failure process of the interface as the strain energy due to the gravitational force accumulates in the rock-mass before it transfers to the sliding interface. Practical implications of the present study are also discussed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011APS..DFD.LA046H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011APS..DFD.LA046H"><span><span class="hlt">Pore</span>-scale Analysis of the effects of Contact Angle Hysteresis on Blob Mobilization in a <span class="hlt">Pore</span> Doublet</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Hsu, Shao-Yiu; Glantz, Roland; Hilpert, Markus</p> <p>2011-11-01</p> <p>The mobilization of residual oil blobs in porous media is of major interest to the petroleum industry. We studied the Jamin effect, which hampers the blob mobilization, experimentally in a <span class="hlt">pore</span> doublet model and explain the Jamin effect through contact angle hysteresis. A liquid blob was trapped in one of the tubes of the <span class="hlt">pore</span> doublet model and then subjected to different <span class="hlt">pressure</span> gradients. We measured the contact angles (in 2D and 3D) as well as the mean curvatures of the blob. Due to gravity effects and hysteresis, the contact angles of the blob were initially (zero <span class="hlt">pressure</span> gradient) non-uniform and exhibited a pronounced altitude dependence. As the <span class="hlt">pressure</span> gradient was increased, the contact angles became more uniform and the altitude dependence of the contact angle decreased. At the same time, the mean curvature of the drainage interface increased, and the mean curvature of the imbibition interface decreased. The <span class="hlt">pressure</span> drops across the <span class="hlt">pore</span> model, which we inferred with our theory from the measured contact angles and mean curvatures, were in line with the directly measured <span class="hlt">pressure</span> data. We not only show that a trapped blob can sustain a finite <span class="hlt">pressure</span> gradient but also develop methods to measure the contact angles and mean curvatures in 3D.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2006AGUFM.V41B1722B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2006AGUFM.V41B1722B"><span>Significance of Dynamic <span class="hlt">Pore</span> <span class="hlt">Pressure</span> Variations - Comparison of Observations on Mud Volcanoes on the Costa Rica Margin and in the Gulf of Cadiz</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Brueckmann, W.; Linke, P.; Pieper, M.; Hensen, C.; Tuerk, M.</p> <p>2006-12-01</p> <p>Research in the cooperative research center (SFB) 574 "Volatiles and Fluids in Subduction Zones" at the University Kiel focuses on volatile and fluid exchange processes at subduction zones. These have a significant impact on the long-term geochemical evolution of the hydrosphere and atmosphere. In the SFB 574 working area off Central America more than 120 mud volcanoes, mud diapirs and cold seeps have been identified and sampled. To better understand the internal dynamics of these structures and the temporal variability of fluid expulsion an in-situ tool for monitoring shallow <span class="hlt">pore</span> <span class="hlt">pressure</span> variations was devised. The tool (PWPL) monitors <span class="hlt">pore</span> <span class="hlt">pressure</span> variations along a 2m profile in the shallow subsurface using a stinger with 4 <span class="hlt">pressure</span> ports. Positioned with a video-guided lander the stinger is gently pushed into the seafloor where it remains for several weeks or months in autonomous mode before being retrieved. While particular emphasis was placed on the convergent margin of Central America, mud volcanoes in other tectonic settings suitable for long-term observations of fluid flux are used for comparison. Here we will present data and interpretations from two mud volcanoes off Costa Rica and in the Gulf of Cadiz where we have conducted successful tests. <span class="hlt">Pore</span> <span class="hlt">pressure</span> data from short-term tests on Mound 11 on the continental slope off Costa Rica are compared with new results from a long-term (3-month) campaign on the Captain Arutjunov deep water mud volcano in the Gulf of Cadiz. Rates of fluid flow at both structures have been thoroughly characterized and quantified with geochemical methods providing a frame of reference for judging the significance of dynamic <span class="hlt">pore</span> <span class="hlt">pressure</span> variations.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_4");'>4</a></li> <li><a href="#" onclick='return showDiv("page_5");'>5</a></li> <li class="active"><span>6</span></li> <li><a href="#" onclick='return showDiv("page_7");'>7</a></li> <li><a href="#" onclick='return showDiv("page_8");'>8</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_6 --> <div id="page_7" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_5");'>5</a></li> <li><a href="#" onclick='return showDiv("page_6");'>6</a></li> <li class="active"><span>7</span></li> <li><a href="#" onclick='return showDiv("page_8");'>8</a></li> <li><a href="#" onclick='return showDiv("page_9");'>9</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="121"> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4642512','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4642512"><span>Micro/Nano-<span class="hlt">pore</span> Network Analysis of Gas Flow in Shale Matrix</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Zhang, Pengwei; Hu, Liming; Meegoda, Jay N.; Gao, Shengyan</p> <p>2015-01-01</p> <p>The gas flow in shale matrix is of great research interests for optimized shale gas extraction. The gas flow in the nano-scale <span class="hlt">pore</span> may fall in flow regimes such as viscous flow, slip flow and Knudsen diffusion. A 3-dimensional nano-scale <span class="hlt">pore</span> network model was developed to simulate dynamic gas flow, and to describe the transient properties of flow regimes. The proposed <span class="hlt">pore</span> network model accounts for the various size distributions and low connectivity of shale <span class="hlt">pores</span>. The <span class="hlt">pore</span> size, <span class="hlt">pore</span> throat size and coordination number obey normal distribution, and the average values can be obtained from shale reservoir data. The gas flow regimes were simulated using an extracted <span class="hlt">pore</span> network backbone. The numerical results show that apparent permeability is strongly dependent on <span class="hlt">pore</span> <span class="hlt">pressure</span> in the reservoir and <span class="hlt">pore</span> throat size, which is overestimated by low-<span class="hlt">pressure</span> laboratory tests. With the decrease of reservoir <span class="hlt">pressure</span>, viscous flow is weakening, then slip flow and Knudsen diffusion are gradually becoming dominant flow regimes. The fingering phenomenon can be predicted by micro/nano-<span class="hlt">pore</span> network for gas flow, which provides an effective way to capture heterogeneity of shale gas reservoir. PMID:26310236</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/26310236','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26310236"><span>Micro/Nano-<span class="hlt">pore</span> Network Analysis of Gas Flow in Shale Matrix.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Zhang, Pengwei; Hu, Liming; Meegoda, Jay N; Gao, Shengyan</p> <p>2015-08-27</p> <p>The gas flow in shale matrix is of great research interests for optimized shale gas extraction. The gas flow in the nano-scale <span class="hlt">pore</span> may fall in flow regimes such as viscous flow, slip flow and Knudsen diffusion. A 3-dimensional nano-scale <span class="hlt">pore</span> network model was developed to simulate dynamic gas flow, and to describe the transient properties of flow regimes. The proposed <span class="hlt">pore</span> network model accounts for the various size distributions and low connectivity of shale <span class="hlt">pores</span>. The <span class="hlt">pore</span> size, <span class="hlt">pore</span> throat size and coordination number obey normal distribution, and the average values can be obtained from shale reservoir data. The gas flow regimes were simulated using an extracted <span class="hlt">pore</span> network backbone. The numerical results show that apparent permeability is strongly dependent on <span class="hlt">pore</span> <span class="hlt">pressure</span> in the reservoir and <span class="hlt">pore</span> throat size, which is overestimated by low-<span class="hlt">pressure</span> laboratory tests. With the decrease of reservoir <span class="hlt">pressure</span>, viscous flow is weakening, then slip flow and Knudsen diffusion are gradually becoming dominant flow regimes. The fingering phenomenon can be predicted by micro/nano-<span class="hlt">pore</span> network for gas flow, which provides an effective way to capture heterogeneity of shale gas reservoir.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015AGUFMNH41C1830H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AGUFMNH41C1830H"><span>Seasonal Effects on the Relationships Between Soil Water Content, <span class="hlt">Pore</span> Water <span class="hlt">Pressure</span> and Shear Strength and Their Implications for Slope Stability</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Hughes, P. N.</p> <p>2015-12-01</p> <p>A soil's shear resistance is mainly dependent upon the magnitude of effective stress. For small to medium height slopes (up to 10m) in clay soils the total stress acting along potential failure planes will be low, therefore the magnitude of effective stress (and hence soil shear strength) will be dominated by the <span class="hlt">pore</span>-water <span class="hlt">pressure</span>. The stability of slopes on this scale through periods of increased precipitation is improved by the generation of negative <span class="hlt">pore</span> <span class="hlt">pressures</span> (soil suctions) during preceding, warmer, drier periods. These negative <span class="hlt">pore</span> water <span class="hlt">pressures</span> increase the effective stress within the soil and cause a corresponding increase in shearing resistance. The relationships between soil water content and <span class="hlt">pore</span> water <span class="hlt">pressure</span> (soil water retention curves) are known to be hysteretic, but for the purposes of the majority of slope stability assessments in partially saturated clay soils, these are assumed to be consistent with time. Similarly, the relationship between shear strength and water content is assumed to be consistent over time. This research presents a laboratory study in which specimens of compacted Glacial Till (typical of engineered slopes within the UK) were subjected to repeated cycles of wetting and drying to simulate seasonal cycles. At predetermined water contents, measurements of soil suction were made using tensiometer and dewpoint potentiometer methods. The undrained shear strength of the specimens was then measured using triaxial strength testing equipment. Results indicate that repeated wetting and drying cycles caused a change in the soil water retention behaviour. A reduction in undrained shear strength at corresponding water contents along the wetting and drying paths was also observed. The mechanism for the change in the relationship is believed to be a deterioration in the soil physical structure due to shrink/swell induced micro-cracking. The non-stationarity of these relationships has implications for slope stability assessment.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012JAG....78...77L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012JAG....78...77L"><span>Modeling seismic stimulation: Enhanced non-aqueous fluid extraction from saturated porous media under <span class="hlt">pore-pressure</span> pulsing at low frequencies</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Lo, Wei-Cheng; Sposito, Garrison; Huang, Yu-Han</p> <p>2012-03-01</p> <p>Seismic stimulation, the application of low-frequency stress-pulsing to the boundary of a porous medium containing water and a non-aqueous fluid to enhance the removal of the latter, shows great promise for both contaminated groundwater remediation and enhanced oil recovery, but theory to elucidate the underlying mechanisms lag significantly behind the progress achieved in experimental research. We address this conceptual lacuna by formulating a boundary-value problem to describe <span class="hlt">pore-pressure</span> pulsing at seismic frequencies that is based on the continuum theory of poroelasticity for an elastic porous medium permeated by two immiscible fluids. An exact analytical solution is presented that is applied numerically using elasticity parameters and hydraulic data relevant to recent proof-of-principle laboratory experiments investigating the stimulation-induced mobilization of trichloroethene (TCE) in water flowing through a compressed sand core. The numerical results indicated that significant stimulation-induced increases of the TCE concentration in effluent can be expected from <span class="hlt">pore-pressure</span> pulsing in the frequency range of 25-100 Hz, which is in good agreement with what was observed in the laboratory experiments. Sensitivity analysis of our numerical results revealed that the TCE concentration in the effluent increases with the porous medium framework compressibility and the pulsing <span class="hlt">pressure</span>. Increasing compressibility also leads to an optimal stimulation response at lower frequencies, whereas changing the pulsing <span class="hlt">pressure</span> does not affect the optimal stimulation frequency. Within the context of our model, the dominant physical cause for enhancement of non-aqueous fluid mobility by seismic stimulation is the dilatory motion of the porous medium in which the solid and fluid phases undergo opposite displacements, resulting in stress-induced changes of the <span class="hlt">pore</span> volume.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016APS..DFDD30008H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016APS..DFDD30008H"><span>A thermodynamically consistent model for granular-fluid mixtures considering <span class="hlt">pore</span> <span class="hlt">pressure</span> evolution and hypoplastic behavior</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Hess, Julian; Wang, Yongqi</p> <p>2016-11-01</p> <p>A new mixture model for granular-fluid flows, which is thermodynamically consistent with the entropy principle, is presented. The extra <span class="hlt">pore</span> <span class="hlt">pressure</span> described by a <span class="hlt">pressure</span> diffusion equation and the hypoplastic material behavior obeying a transport equation are taken into account. The model is applied to granular-fluid flows, using a closing assumption in conjunction with the dynamic fluid <span class="hlt">pressure</span> to describe the <span class="hlt">pressure</span>-like residual unknowns, hereby overcoming previous uncertainties in the modeling process. Besides the thermodynamically consistent modeling, numerical simulations are carried out and demonstrate physically reasonable results, including simple shear flow in order to investigate the vertical distribution of the physical quantities, and a mixture flow down an inclined plane by means of the depth-integrated model. Results presented give insight in the ability of the deduced model to capture the key characteristics of granular-fluid flows. We acknowledge the support of the Deutsche Forschungsgemeinschaft (DFG) for this work within the Project Number WA 2610/3-1.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/pages/biblio/1237361-pore-scale-investigation-stress-dependent-characteristics-granular-packs-impact-pore-deformation-fluid-distribution','SCIGOV-DOEP'); return false;" href="https://www.osti.gov/pages/biblio/1237361-pore-scale-investigation-stress-dependent-characteristics-granular-packs-impact-pore-deformation-fluid-distribution"><span><span class="hlt">Pore</span>-scale investigation on stress-dependent characteristics of granular packs and the impact of <span class="hlt">pore</span> deformation on fluid distribution</span></a></p> <p><a target="_blank" href="http://www.osti.gov/pages">DOE PAGES</a></p> <p>Yoon, Hongkyu; Klise, Katherine A.; Torrealba, Victor A.; ...</p> <p>2015-05-25</p> <p>Understanding the effect of changing stress conditions on multiphase flow in porous media is of fundamental importance for many subsurface activities including enhanced oil recovery, water drawdown from aquifers, soil confinement, and geologic carbon storage. Geomechanical properties of complex porous systems are dynamically linked to flow conditions, but their feedback relationship is often oversimplified due to the difficulty of representing <span class="hlt">pore</span>-scale stress deformation and multiphase flow characteristics in high fidelity. In this work, we performed <span class="hlt">pore</span>-scale experiments of single- and multiphase flow through bead packs at different confining <span class="hlt">pressure</span> conditions to elucidate compaction-dependent characteristics of granular packs and their impactmore » on fluid flow. A series of drainage and imbibition cycles were conducted on a water-wet, soda-lime glass bead pack under varying confining stress conditions. Simultaneously, X-ray micro-CT was used to visualize and quantify the degree of deformation and fluid distribution corresponding with each stress condition and injection cycle. Micro-CT images were segmented using a gradient-based method to identify fluids (e.g., oil and water), and solid phase redistribution throughout the different experimental stages. Changes in porosity, tortuosity, and specific surface area were quantified as a function of applied confining <span class="hlt">pressure</span>. Results demonstrate varying degrees of sensitivity of these properties to confining <span class="hlt">pressure</span>, which suggests that caution must be taken when considering scalability of these properties for practical modeling purposes. Changes in capillary number with confining <span class="hlt">pressure</span> are attributed to the increase in <span class="hlt">pore</span> velocity as a result of <span class="hlt">pore</span> contraction. Furthermore, this increase in <span class="hlt">pore</span> velocity was found to have a marginal impact on average phase trapping at different confining <span class="hlt">pressures</span>.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/19366586','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/19366586"><span>Extrusion of transmitter, water and ions generates forces to close fusion <span class="hlt">pore</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Tajparast, M; Glavinović, M I</p> <p>2009-05-01</p> <p>During exocytosis the fusion <span class="hlt">pore</span> opens rapidly, then dilates gradually, and may subsequently close completely, but what controls its dynamics is not well understood. In this study we focus our attention on forces acting on the <span class="hlt">pore</span> wall, and which are generated solely by the passage of transmitter, ions and water through the open fusion <span class="hlt">pore</span>. The transport through the charged cylindrical nano-size <span class="hlt">pore</span> is simulated using a coupled system of Poisson-Nernst-Planck and Navier-Stokes equations and the forces that act radially on the wall of the fusion <span class="hlt">pore</span> are then estimated. Four forces are considered: a) inertial force, b) <span class="hlt">pressure</span>, c) viscotic force, and d) electrostatic force. The inertial and viscotic forces are small, but the electrostatic force and the <span class="hlt">pressure</span> are typically significant. High vesicular <span class="hlt">pressure</span> tends to open the fusion <span class="hlt">pore</span>, but the <span class="hlt">pressure</span> induced by the transport of charged particles (glutamate, ions), which is predominant when the <span class="hlt">pore</span> wall charge density is high tends to close the <span class="hlt">pore</span>. The electrostatic force, which also depends on the charge density on the <span class="hlt">pore</span> wall, is weakly repulsive before the <span class="hlt">pore</span> dilates, but becomes attractive and pronounced as the <span class="hlt">pore</span> dilates. Given that the vesicular concentration of free transmitter can change rapidly due to the release, or owing to the dissociation from the gel matrix, we evaluated how much and how rapidly a change of the vesicular K(+)-glutamate(-) concentration affects the concentration of glutamate(-) and ions in the <span class="hlt">pore</span> and how such changes alter the radial force on the wall of the fusion <span class="hlt">pore</span>. A step-like rise of the vesicular K(+)-glutamate(-) concentration leads to a chain of events. <span class="hlt">Pore</span> concentration (and efflux) of both K(+) and glutamate(-) rise reaching their new steady-state values in less than 100 ns. Interestingly within a similar time interval the <span class="hlt">pore</span> concentration of Na(+) also rises, whereas that of Cl(-) diminishes, although their extra-cellular concentration does not</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018JOUC...17...25X','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018JOUC...17...25X"><span>Sediment compaction and <span class="hlt">pore</span> <span class="hlt">pressure</span> prediction in deepwater basin of the South China Sea: Estimation from ODP and IODP drilling well data</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Xie, Yangbing; Wu, Tuoyu; Sun, Jin; Zhang, Hanyu; Wang, Jiliang; Gao, Jinwei; Chen, Chuanxu</p> <p>2018-02-01</p> <p>Overpressure in deepwater basins not only causes serious soft sediment deformation, but also significantly affects the safety of drilling operations. Therefore, prediction of overpressure in sediments has become an important task in deepwater oil exploration and development. In this study, we analyze the drilling data from ODP Leg 184 Sites 1144, 1146, and 1148, and IODP Leg 349 Sites U1431, U1432, U1433, and U1435 to study the sediment compaction and controls in the northern South China Sea. Sedimentation rate, sediment content, distribution area, and buried depth are the factors that influence sediment compaction in the deepwater basin of the South China Sea. Among these factors, the sediment content is the most important. The fitted normal compacted coefficients and mudline porosity for an interval of 50 m shows disciplinary variation versus depth. The <span class="hlt">pore</span> <span class="hlt">pressure</span> predicted from different fitted results shows varying overpressure situations. The normal compaction trend from Site 1144 reflects the porosity variation trend in stable deposition basins in the northern South China Sea. The predicted <span class="hlt">pore</span> <span class="hlt">pressure</span> shows overpressure at Site 1144, which is attributed to compaction disequilibrium. Nevertheless, the mixed lithology column may influence the predicted over-<span class="hlt">pressure</span> at Site 1148, which is responsible for the confusing result. Above all, we find that sediment compaction should serve as a proxy for <span class="hlt">pore</span> <span class="hlt">pressure</span> in the deepwater basin of the South China Sea.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/19926207','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/19926207"><span>In situ measurement of soil moisture and <span class="hlt">pore</span>-water <span class="hlt">pressures</span> in an 'incipient' landslide: Lake Tutira, New Zealand.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Hawke, Richard; McConchie, Jack</p> <p>2011-02-01</p> <p>The immediate cost of shallow regolith landslides in New Zealand has been estimated to exceed US$33M annually. Since the majority of these landslides occur during prolonged wet conditions, or intense rainstorms, moisture conditions are a critical control. The nature, dynamics, and character of soil moisture conditions, and the piezometric response to rainfall, have been recorded within an 'incipient' landslide for more than 5 years. The study site, on pastoral hill country within the Lake Tutira catchment in northern Hawkes Bay, is typical of large areas of New Zealand episodically affected by extensive landsliding. Detailed continuous measurements show that both the soil moisture and piezometric response within the regolith are highly storm- and site-specific. The development of positive <span class="hlt">pore</span> <span class="hlt">pressures</span> is infrequent; they form only during intense rainstorms, and persist for a short time. The hydraulic response of the soil is primarily a function of storm characteristics, but this response can be modified by antecedent moisture conditions, topographic position, and heterogeneity of soil properties. Stability analysis shows that most slopes in the study area are significantly steeper than can be explained by the frictional strength of the regolith. Measured hydraulic conditions also show that positive <span class="hlt">pore</span>-water <span class="hlt">pressures</span> alone do not trigger slope instability. A recent slope failure followed a period of extremely high antecedent moisture conditions, and occurred when maximum soil moisture conditions, though not <span class="hlt">pore</span>-water <span class="hlt">pressures</span>, were recorded. Increased moisture content of the regolith reduces matric tension, and therefore effective cohesion of the soil. This cohesion is critical to maintaining stability of the regolith on these slopes. Copyright © 2009 Elsevier Ltd. All rights reserved.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/29126762','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/29126762"><span>Association between <span class="hlt">abnormal</span> nocturnal blood <span class="hlt">pressure</span> profile and dementia in Parkinson's disease.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Tanaka, Ryota; Shimo, Yasushi; Yamashiro, Kazuo; Ogawa, Takashi; Nishioka, Kenya; Oyama, Genko; Umemura, Atsushi; Hattori, Nobutaka</p> <p>2018-01-01</p> <p>Circadian blood <span class="hlt">pressure</span> alterations are frequently observed in Parkinson's disease, but the association between these changes and dementia in the condition remains unclear. Here, we assess the relationship between <span class="hlt">abnormal</span> nocturnal blood <span class="hlt">pressure</span> profiles and dementia in Parkinson's disease. We enrolled 137 patients with Parkinson's disease, who underwent 24 h ambulatory blood <span class="hlt">pressure</span> monitoring, following cognitive and clinical assessment. Twenty-seven patients (19.7%) were diagnosed with dementia in this cohort. We observed significant associations of dementia with age, male gender, Hoehn-Yahr (H-Y) stage, diabetes mellitus, history of stroke, presence of cerebrovascular lesions on MRI, and orthostatic hypotension. Univariate logistic regression analysis showed that among the patterns of nocturnal blood <span class="hlt">pressure</span> profiles, the riser pattern was significantly associated with dementia (OR 11.6, 95%CI: 2.14-215.0, P < 0.01), and this trend was observed after adjusting for all confounding factors except orthostatic hypotension (OR 19.2, 95%CI: 1.12-1960.3, P = 0.04). However, coexistence of a riser pattern and orthostatic hypotension was related to a higher prevalence of dementia (45.2%) than was a riser pattern alone (9.5%). Furthermore, coexistence of a riser pattern and orthostatic hypotension was significantly more associated with dementia than was a riser pattern alone, even after adjusting for confounders (OR 1625.1, 95%CI: 21.9-1343909.5, P < 0.01). Our results suggest a relationship between a riser pattern coexisting with orthostatic hypotension and dementia in Parkinson's disease. Further prospective studies are warranted to investigate whether <span class="hlt">abnormal</span> nocturnal blood <span class="hlt">pressure</span> profiles predict dementia in Parkinson's disease. Copyright © 2017 Elsevier Ltd. All rights reserved.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/24955384','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/24955384"><span>Numerical simulation on hydromechanical coupling in porous media adopting three-dimensional <span class="hlt">pore</span>-scale model.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Liu, Jianjun; Song, Rui; Cui, Mengmeng</p> <p>2014-01-01</p> <p>A novel approach of simulating hydromechanical coupling in <span class="hlt">pore</span>-scale models of porous media is presented in this paper. Parameters of the sandstone samples, such as the stress-strain curve, Poisson's ratio, and permeability under different <span class="hlt">pore</span> <span class="hlt">pressure</span> and confining <span class="hlt">pressure</span>, are tested in laboratory scale. The micro-CT scanner is employed to scan the samples for three-dimensional images, as input to construct the model. Accordingly, four physical models possessing the same <span class="hlt">pore</span> and rock matrix characteristics as the natural sandstones are developed. Based on the micro-CT images, the three-dimensional finite element models of both rock matrix and <span class="hlt">pore</span> space are established by MIMICS and ICEM software platform. Navier-Stokes equation and elastic constitutive equation are used as the mathematical model for simulation. A hydromechanical coupling analysis in <span class="hlt">pore</span>-scale finite element model of porous media is simulated by ANSYS and CFX software. Hereby, permeability of sandstone samples under different <span class="hlt">pore</span> <span class="hlt">pressure</span> and confining <span class="hlt">pressure</span> has been predicted. The simulation results agree well with the benchmark data. Through reproducing its stress state underground, the prediction accuracy of the porous rock permeability in <span class="hlt">pore</span>-scale simulation is promoted. Consequently, the effects of <span class="hlt">pore</span> <span class="hlt">pressure</span> and confining <span class="hlt">pressure</span> on permeability are revealed from the microscopic view.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4032763','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4032763"><span>Numerical Simulation on Hydromechanical Coupling in Porous Media Adopting Three-Dimensional <span class="hlt">Pore</span>-Scale Model</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Liu, Jianjun; Song, Rui; Cui, Mengmeng</p> <p>2014-01-01</p> <p>A novel approach of simulating hydromechanical coupling in <span class="hlt">pore</span>-scale models of porous media is presented in this paper. Parameters of the sandstone samples, such as the stress-strain curve, Poisson's ratio, and permeability under different <span class="hlt">pore</span> <span class="hlt">pressure</span> and confining <span class="hlt">pressure</span>, are tested in laboratory scale. The micro-CT scanner is employed to scan the samples for three-dimensional images, as input to construct the model. Accordingly, four physical models possessing the same <span class="hlt">pore</span> and rock matrix characteristics as the natural sandstones are developed. Based on the micro-CT images, the three-dimensional finite element models of both rock matrix and <span class="hlt">pore</span> space are established by MIMICS and ICEM software platform. Navier-Stokes equation and elastic constitutive equation are used as the mathematical model for simulation. A hydromechanical coupling analysis in <span class="hlt">pore</span>-scale finite element model of porous media is simulated by ANSYS and CFX software. Hereby, permeability of sandstone samples under different <span class="hlt">pore</span> <span class="hlt">pressure</span> and confining <span class="hlt">pressure</span> has been predicted. The simulation results agree well with the benchmark data. Through reproducing its stress state underground, the prediction accuracy of the porous rock permeability in <span class="hlt">pore</span>-scale simulation is promoted. Consequently, the effects of <span class="hlt">pore</span> <span class="hlt">pressure</span> and confining <span class="hlt">pressure</span> on permeability are revealed from the microscopic view. PMID:24955384</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1983AtmEn..17..115J','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1983AtmEn..17..115J"><span>Characteristics of nuclepore filters with large <span class="hlt">pore</span> size—I. Physical properties</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>John, W.; Hering, S.; Reischl, G.; Sasaki, G.; Goren, S.</p> <p></p> <p>Measurements of <span class="hlt">pore</span> diameter, <span class="hlt">pore</span> density and filter thickness have been made on Nuclepore filters of 5, 8 and 12 μm <span class="hlt">pore</span> size. The areal distribution of the <span class="hlt">pores</span> is random, as verified by total hole counts and by counts of overlapping holes. Filter thicknesses decrease with increasing <span class="hlt">pore</span> diameter. The Hagen-Poiseuille formula accounts for less than half of the measured <span class="hlt">pressure</span> drop across 12 μm <span class="hlt">pore</span> size filters. A new calculation, including a term for the <span class="hlt">pressure</span> drop external to the filter, accounts quantitatively for the observations. There are sufficient variations among filter batches to require knowledge of the filter parameters for each batch to ensure accurate measurements using these filters.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010JGRB..115.4405Z','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010JGRB..115.4405Z"><span>Micromechanics of cataclastic <span class="hlt">pore</span> collapse in limestone</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Zhu, Wei; Baud, Patrick; Wong, Teng-Fong</p> <p>2010-04-01</p> <p>The analysis of compactant failure in carbonate formations hinges upon a fundamental understanding of the mechanics of inelastic compaction. Microstructural observations indicate that <span class="hlt">pore</span> collapse in a limestone initiates at the larger <span class="hlt">pores</span>, and microcracking dominates the deformation in the periphery of a collapsed <span class="hlt">pore</span>. To capture these micromechanical processes, we developed a model treating the limestone as a dual porosity medium, with the total porosity partitioned between macroporosity and microporosity. The representative volume element is made up of a large <span class="hlt">pore</span> which is surrounded by an effective medium containing the microporosity. Cataclastic yielding of this effective medium obeys the Mohr-Coulomb or Drucker-Prager criterion, with failure parameters dependent on porosity and <span class="hlt">pore</span> size. An analytic approximation was derived for the unconfined compressive strength associated with failure due to the propagation and coalescence of <span class="hlt">pore</span>-emanated cracks. For hydrostatic loading, identical theoretical results for the <span class="hlt">pore</span> collapse <span class="hlt">pressure</span> were obtained using the Mohr-Coulomb or Drucker-Prager criterion. For nonhydrostatic loading, the stress state at the onset of shear-enhanced compaction was predicted to fall on a linear cap according to the Mohr-Coulomb criterion. In contrast, nonlinear caps in qualitative agreement with laboratory data were predicted using the Drucker-Prager criterion. Our micromechanical model implies that the effective medium is significantly stronger and relatively <span class="hlt">pressure</span>-insensitive in comparison to the bulk sample.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018Geomo.308...40Z','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018Geomo.308...40Z"><span>Effect of excess <span class="hlt">pore</span> <span class="hlt">pressure</span> on the long runout of debris flows over low gradient channels: A case study of the Dongyuege debris flow in Nu River, China</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Zhou, Zhen-Hua; Ren, Zhe; Wang, Kun; Yang, Kui; Tang, Yong-Jun; Tian, Lin; Xu, Ze-Min</p> <p>2018-05-01</p> <p>Debris flows with long reaches are one of the major natural hazards to human life and property on alluvial fans, as shown by the debris flow that occurred in the Dongyuege (DYG) Gully in August 18, 2010, and caused 96 deaths. The travel distance and the runout distance of the DYG large-scale tragic debris flow were 11 km and 9 km, respectively. In particular, the runout distance over the low gradient channel (channel slope < 5°) upstream of the depositional fan apex reached up to 3.3 km. The build-up and maintenance of excess <span class="hlt">pore</span> <span class="hlt">pressure</span> in the debris-flow mass might have played a crucial role in the persistence and long runout of the bouldery viscous debris flow. Experiments to measure <span class="hlt">pore</span> <span class="hlt">pressure</span> and <span class="hlt">pore</span> water escape have been carried out by reconstituting the debris flow bodies with the DYG debris flow deposit. The slurrying of the debris is governed by solid volumetric concentration (SVC), and the difference between the lower SVC limit and the upper SVC limit can be defined as debris flow index (Id). Peak value (Kp) and rate of dissipation (R) of relative excess <span class="hlt">pore</span> <span class="hlt">pressure</span> are dependent on SVC. Further, the SVC that gives the lowest rate of dissipation is regarded as the optimum SVC (Cvo). The dissipation response of excess <span class="hlt">pore</span> <span class="hlt">pressure</span> can be characterized by the R value under Cvo at a given moment (i.e., 0.5 h, 1 h or 2 h later after peak time). The results reveal that a relatively high level of excess <span class="hlt">pore</span> <span class="hlt">pressure</span> developed within the DYG debris-flow mass and had a strong persistence capability. Further research shows that the development, peak value and dissipation of excess <span class="hlt">pore</span> <span class="hlt">pressure</span> in a mixture of sediment and water are related to the maximum grain size (MGS), gradation and mineralogy of clay-size particles of the sediment. The layer-lattice silicates in clay particles can be the typical clay minerals, including kaolinite, montmorillonite and illite, and also the unrepresentative clay minerals such as muscovite and chlorite. Moreover</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014EGUGA..16..158B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014EGUGA..16..158B"><span>Comparison between monitored and modeled <span class="hlt">pore</span> water <span class="hlt">pressure</span> and safety factor in a slope susceptible to shallow landslides</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Bordoni, Massimiliano; Meisina, Claudia; Zizioli, Davide; Valentino, Roberto; Bittelli, Marco; Chersich, Silvia</p> <p>2014-05-01</p> <p>Shallow landslides can be defined as slope movements affecting superficial deposits of small thicknesses which are usually triggered due to extreme rainfall events, also very concentrated in time. Shallow landslides are hazardous phenomena: in particular, if they happen close to urbanized areas they could cause significant damages to cultivations, structures, infrastructures and, sometimes, human losses. The triggering mechanism of rainfall-induced shallow landslides is strictly linked with the hydrological and mechanical responses of usually unsaturated soils to rainfall events. For this reason, it is fundamental knowing the intrinsic hydro-mechanical properties of the soils in order to assess both susceptibility and hazard of shallow landslide and to develop early-warning systems at large scale. The hydrological data collected by a 20 months monitoring on a slope susceptible to shallow landslides in an area of the North -Eastern Oltrepo Pavese (Northern Apennines, Italy) were used to identify the hydrological behaviors of the investigated soils towards rainfall events. Field conditions under different rainfall trends have also been modeled by using both hydrological and physically-based stability models for the evaluation of the slope safety factor . The main objectives of this research are: (a) to compare the field measured <span class="hlt">pore</span> water <span class="hlt">pressures</span> at different depths with results of hydrological models, in order to evaluate the efficiency of the tested models and to determine how precipitations affect <span class="hlt">pore</span> <span class="hlt">pressure</span> development; (b) to compare the time trends of the safety factor that have been obtained by applying different stability models; (c) to evaluate, through a sensitivity analysis, the effects of soil hydrological properties on modeling <span class="hlt">pore</span> water <span class="hlt">pressure</span> and safety factor. The test site slope where field measurements were acquired is representative of other sites in Northern Apennines affected by shallow landslides and is characterized by medium</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018GeoRL..45..682P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018GeoRL..45..682P"><span><span class="hlt">Pore</span> <span class="hlt">Pressure</span> Pulse Drove the 2012 Emilia (Italy) Series of Earthquakes</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Pezzo, Giuseppe; De Gori, Pasquale; Lucente, Francesco Pio; Chiarabba, Claudio</p> <p>2018-01-01</p> <p>The 2012 Emilia earthquakes sequence is the first debated case in Italy of destructive event possibly induced by anthropic activity. During this sequence, two main earthquakes occurred separated by 9 days on contiguous thrust faults. Scientific commissions engaged by the Italian government reported complementary scenarios on the potential trigger mechanism ascribable to exploitation of a nearby oil field. In this study, we combine a refined geodetic source model constrained by precise aftershock locations and an improved tomographic model of the area to define the geometrical relation between the activated faults and investigate possible triggering mechanisms. An aftershock decay rate that deviates from the classical Omori-like pattern and <fi>Vp</fi>/<fi>Vs</fi> changes along the fault system suggests that natural <span class="hlt">pore</span> <span class="hlt">pressure</span> pulse drove the space-time evolution of seismicity and the activation of the second main shock.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011AGUFMMR51A2150Z','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011AGUFMMR51A2150Z"><span><span class="hlt">Pore</span> Structure Model for Predicting Elastic Wavespeeds in Fluid-Saturated Sandstones</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Zimmerman, R. W.; David, E. C.</p> <p>2011-12-01</p> <p>During hydrostatic compression, in the elastic regime, ultrasonic P and S wave velocities measured on rock cores generally increase with <span class="hlt">pressure</span>, and reach asymptotic values at high <span class="hlt">pressures</span>. The <span class="hlt">pressure</span> dependence of seismic velocities is generally thought to be due to the closure of compliant cracks, in which case the high-<span class="hlt">pressure</span> velocities must reflect only the influence of the non-closable, equant "<span class="hlt">pores</span>". Assuming that <span class="hlt">pores</span> can be represented by spheroids, we can relate the elastic properties to the <span class="hlt">pore</span> structure using an effective medium theory. Moreover, the closure <span class="hlt">pressure</span> of a thin crack-like <span class="hlt">pore</span> is directly proportional to its aspect ratio. Hence, our first aim is to use the <span class="hlt">pressure</span> dependence of seismic velocities to invert the aspect ratio distribution. We use a simple analytical algorithm developed by Zimmerman (Compressibility of Sandstones, 1991), which can be used for any effective medium theory. Previous works have used overly restrictive assumptions, such as assuming that the stiff <span class="hlt">pores</span> are spherical, or that the interactions between <span class="hlt">pores</span> can be neglected. Here, we assume that the rock contains an exponential distribution of crack aspect ratios, and one family of stiff <span class="hlt">pores</span> having an aspect ratio lying somewhere between 0.01 and 1. We develop our model in two versions, using the Differential Scheme, and the Mori-Tanaka scheme. The inversion is done using data obtained in dry experiments, since <span class="hlt">pore</span> fluids have a strong effect on velocities and tend to mask the effect of the <span class="hlt">pore</span> geometry. This avoids complicated joint inversion of dry and wet data, such as done by Cheng and Toksoz (JGR, 1979). Our results show that for many sets of data on sandstones, we can fit very well the dry velocities. Our second aim is to predict the saturated velocities from our <span class="hlt">pore</span> structure model, noting that at a given differential stress, the <span class="hlt">pore</span> structure should be the same as for a dry test. Our results show that the Biot-Gassmann predictions always</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2005AGUFM.T53B1431Z','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2005AGUFM.T53B1431Z"><span>Development of a New Analog Test System Capable of Modeling Tectonic Deformation Incorporating the Effects of <span class="hlt">Pore</span> Fluid <span class="hlt">Pressure</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Zhang, M.; Nakajima, H.; Takeda, M.; Aung, T. T.</p> <p>2005-12-01</p> <p>Understanding and predicting the tectonic deformation within geologic strata has been a very important research subject in many fields such as structural geology and petroleum geology. In recent years, such research has also become a fundamental necessity for the assessment of active fault migration, site selection for geological disposal of radioactive nuclear waste and exploration for methane hydrate. Although analog modeling techniques have played an important role in the elucidation of the tectonic deformation mechanisms, traditional approaches have typically used dry materials and ignored the effects of <span class="hlt">pore</span> fluid <span class="hlt">pressure</span>. In order for analog models to properly depict the tectonic deformation of the targeted, large-prototype system within a small laboratory-scale configuration, physical properties of the models, including geometry, force, and time, must be correctly scaled. Model materials representing brittle rock behavior require an internal friction identical to the prototype rock and virtually zero cohesion. Granular materials such as sand, glass beads, or steel beads of dry condition have been preferably used for this reason in addition to their availability and ease of handling. Modeling protocols for dry granular materials have been well established but such model tests cannot account for the <span class="hlt">pore</span> fluid effects. Although the concept of effective stress has long been recognized and the role of <span class="hlt">pore</span>-fluid <span class="hlt">pressure</span> in tectonic deformation processes is evident, there have been few analog model studies that consider the effects of <span class="hlt">pore</span> fluid movement. Some new applications require a thorough understanding of the coupled deformation and fluid flow processes within the strata. Taking the field of waste management as an example, deep geological disposal of radioactive waste has been thought to be an appropriate methodology for the safe isolation of the wastes from the human environment until the toxicity of the wastes decays to non-hazardous levels. For the</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011AGUFM.T13A2355V','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011AGUFM.T13A2355V"><span>Slip-weakening zone sizes at nucleation of catastrophic subaerial and submarine landslides by gradually increasing <span class="hlt">pore</span> <span class="hlt">pressure</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Viesca, R. C.; Rice, J. R.</p> <p>2011-12-01</p> <p>We address the nucleation of dynamic landslide rupture in response to gradual <span class="hlt">pore</span> <span class="hlt">pressure</span> increases. Nucleation marks the onset of acceleration of the overlying slope mass due to the suddenly rapid enlargement of a sub-surface zone of shear failure, previously deforming quasi-statically. We model that zone as a planar surface undergoing initially linear slip-weakening frictional failure within a bordering linear-elastic medium. The results are also relevant to earthquake nucleation. The sub-surface rupture zone considered runs parallel to the free surface of a uniform slope, under a 2D plane-strain deformation state. We show results for ruptures with friction coefficients following linear slip weakening (i.e., the residual friction is not yet reached). For spatially broad increases in <span class="hlt">pore</span> <span class="hlt">pressure</span>, the nucleation length depends on a ratio of depth to a cohesive zone length scale. In the very broad-increase limit, a direct numerical solution for nucleation lengths compares well with solutions to a corresponding eigenvalue problem (similar to Uenishi and Rice [JGR '03]), in which spatial variations in normal stress are neglected. We estimate nucleation lengths for subaerial and submarine conditions using data [e.g., Bishop et al., Géotech. '71; Stark et al., JGGE '05] from ring-shear tests on sediments (peak friction fp = 0.5, frictional slip-weakening rate within the range w = -df/d(slip) = 0.1/cm-1/cm). We assume that only pre-stresses, and not material properties, vary with depth. With such fp and w, we find for a range of subsurface depths and shear moduli μ that nucleation lengths are typically several hundred meters long for shallow undersea slopes, and up to an order of magnitude less for steeper slopes on the Earth's surface. In the submarine case, this puts nucleation lengths in a size range comparable to observed <span class="hlt">pore-pressure</span>-generated seafloor disturbances as pockmarks [e.g., Gay et al., MG '06].</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_5");'>5</a></li> <li><a href="#" onclick='return showDiv("page_6");'>6</a></li> <li class="active"><span>7</span></li> <li><a href="#" onclick='return showDiv("page_8");'>8</a></li> <li><a href="#" onclick='return showDiv("page_9");'>9</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_7 --> <div id="page_8" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_6");'>6</a></li> <li><a href="#" onclick='return showDiv("page_7");'>7</a></li> <li class="active"><span>8</span></li> <li><a href="#" onclick='return showDiv("page_9");'>9</a></li> <li><a href="#" onclick='return showDiv("page_10");'>10</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="141"> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/27014386','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/27014386"><span>Intra-Ocular <span class="hlt">Pressure</span> Measurement in a Patient with a Thin, Thick or <span class="hlt">Abnormal</span> Cornea.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Clement, Colin I; Parker, Douglas G A; Goldberg, Ivan</p> <p>2016-01-01</p> <p>Accurate measurement of intra-ocular <span class="hlt">pressure</span> is a fundamental component of the ocular examination. The most common method of measuring IOP is by Goldmann applanation tonometry, the accuracy of which is influenced by the thickness and biomechanical properties of the cornea. Algorithms devised to correct for corneal thickness to estimate IOP oversimplify the effects of corneal biomechanics. The viscous and elastic properties of the cornea influence IOP measurements in unpredictable ways, a finding borne out in studies of patients with inherently <span class="hlt">abnormal</span> and surgically altered corneal biomechanics. Dynamic contour tonometry, rebound tonometry and the ocular response analyzer provide useful alternatives to GAT in patients with <span class="hlt">abnormal</span> corneas, such as those who have undergone laser vision correction or keratoplasty. This article reviews the various methods of intra-ocular <span class="hlt">pressure</span> measurement available to the clinician and the ways in which their utility is influenced by variations in corneal thickness and biomechanics.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2005AGUFM.T11E..05L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2005AGUFM.T11E..05L"><span><span class="hlt">Pore</span> <span class="hlt">Pressure</span> Evolution in Shallow Subduction Earthquake Sequences and Effects on Aseismic Slip Transients -- Numerical Modeling With Rate and State Friction</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Liu, Y.; Rice, J. R.</p> <p>2005-12-01</p> <p>In 3D modeling of long tectonic loading and earthquake sequences on a shallow subduction fault [Liu and Rice, 2005], with depth-variable rate and state friction properties, we found that aseismic transient slip episodes emerge spontaneously with only a simplified representation of effects of metamorphic fluid release. That involved assumption of a constant in time but uniformly low effective normal stress in the downdip region. As suggested by observations in several major subduction zones [Obara, 2002; Rogers and Dragert, 2003; Kodaira et al, 2004], the presence of fluids, possibly released from dehydration reactions beneath the seismogenic zone, and their <span class="hlt">pressurization</span> within the fault zone may play an important role in causing aseismic transients and associated non-volcanic tremors. To investigate the effects of fluids in the subduction zone, particularly on the generation of aseismic transients and their various features, we develop a more complete physical description of the <span class="hlt">pore</span> <span class="hlt">pressure</span> evolution (specifically, <span class="hlt">pore</span> <span class="hlt">pressure</span> increase due to supply from dehydration reactions and shear heating, decrease due to transport and dilatancy during slip), and incorporate that into the rate and state based 3D modeling. We first incorporated two important factors, dilatancy and shear heating, following Segall and Rice [1995, 2004] and Taylor [1998]. In the 2D simulations (slip varies with depth only), a dilatancy-stabilizing effect is seen which slows down the seismic rupture front and can prevent rapid slip from extending all the way to the trench, similarly to Taylor [1998]. Shear heating increases the <span class="hlt">pore</span> <span class="hlt">pressure</span>, and results in faster coseismic rupture propagation and larger final slips. In the 3D simulations, dilatancy also stabilizes the along-strike rupture propagation of both seismic and aseismic slips. That is, aseismic slip transients migrate along the strike faster with a shorter Tp (the characteristic time for <span class="hlt">pore</span> <span class="hlt">pressure</span> in the fault core to re</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5459163','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5459163"><span><span class="hlt">Pore</span>-Scale Simulation and Sensitivity Analysis of Apparent Gas Permeability in Shale Matrix</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Zhang, Pengwei; Hu, Liming; Meegoda, Jay N.</p> <p>2017-01-01</p> <p>Extremely low permeability due to nano-scale <span class="hlt">pores</span> is a distinctive feature of gas transport in a shale matrix. The permeability of shale depends on <span class="hlt">pore</span> <span class="hlt">pressure</span>, porosity, <span class="hlt">pore</span> throat size and gas type. The <span class="hlt">pore</span> network model is a practical way to explain the macro flow behavior of porous media from a microscopic point of view. In this research, gas flow in a shale matrix is simulated using a previously developed three-dimensional <span class="hlt">pore</span> network model that includes typical bimodal <span class="hlt">pore</span> size distribution, anisotropy and low connectivity of the <span class="hlt">pore</span> structure in shale. The apparent gas permeability of shale matrix was calculated under different reservoir <span class="hlt">pressures</span> corresponding to different gas exploitation stages. Results indicate that gas permeability is strongly related to reservoir gas <span class="hlt">pressure</span>, and hence the apparent permeability is not a unique value during the shale gas exploitation, and simulations suggested that a constant permeability for continuum-scale simulation is not accurate. Hence, the reservoir <span class="hlt">pressures</span> of different shale gas exploitations should be considered. In addition, a sensitivity analysis was also performed to determine the contributions to apparent permeability of a shale matrix from petro-physical properties of shale such as <span class="hlt">pore</span> throat size and porosity. Finally, the impact of connectivity of nano-scale <span class="hlt">pores</span> on shale gas flux was analyzed. These results would provide an insight into understanding nano/micro scale flows of shale gas in the shale matrix. PMID:28772465</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/28772465','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/28772465"><span><span class="hlt">Pore</span>-Scale Simulation and Sensitivity Analysis of Apparent Gas Permeability in Shale Matrix.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Zhang, Pengwei; Hu, Liming; Meegoda, Jay N</p> <p>2017-01-25</p> <p>Extremely low permeability due to nano-scale <span class="hlt">pores</span> is a distinctive feature of gas transport in a shale matrix. The permeability of shale depends on <span class="hlt">pore</span> <span class="hlt">pressure</span>, porosity, <span class="hlt">pore</span> throat size and gas type. The <span class="hlt">pore</span> network model is a practical way to explain the macro flow behavior of porous media from a microscopic point of view. In this research, gas flow in a shale matrix is simulated using a previously developed three-dimensional <span class="hlt">pore</span> network model that includes typical bimodal <span class="hlt">pore</span> size distribution, anisotropy and low connectivity of the <span class="hlt">pore</span> structure in shale. The apparent gas permeability of shale matrix was calculated under different reservoir <span class="hlt">pressures</span> corresponding to different gas exploitation stages. Results indicate that gas permeability is strongly related to reservoir gas <span class="hlt">pressure</span>, and hence the apparent permeability is not a unique value during the shale gas exploitation, and simulations suggested that a constant permeability for continuum-scale simulation is not accurate. Hence, the reservoir <span class="hlt">pressures</span> of different shale gas exploitations should be considered. In addition, a sensitivity analysis was also performed to determine the contributions to apparent permeability of a shale matrix from petro-physical properties of shale such as <span class="hlt">pore</span> throat size and porosity. Finally, the impact of connectivity of nano-scale <span class="hlt">pores</span> on shale gas flux was analyzed. These results would provide an insight into understanding nano/micro scale flows of shale gas in the shale matrix.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016AGUFM.S44C..05K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016AGUFM.S44C..05K"><span>Using regional <span class="hlt">pore</span>-fluid <span class="hlt">pressure</span> response following the 3 Sep 2016 M­­w5.8 Pawnee, Oklahoma earthquake to constrain far-field seismicity rate forecasts</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kroll, K.; Murray, K. E.; Cochran, E. S.</p> <p>2016-12-01</p> <p>The 3 Sep 2016 M­­w5.8 Pawnee, Oklahoma earthquake was the largest event to occur in recorded history of the state. Widespread shaking from the event was felt in seven central U.S. states and caused damage as far away as Oklahoma City ( 115 km SSW). The Pawnee earthquake occurred soon after the deployment of a subsurface <span class="hlt">pore</span>-fluid <span class="hlt">pressure</span> monitoring network in Aug 2016. Eight <span class="hlt">pressure</span> transducers were installed downhole in inactive saltwater disposal wells that were completed in the basal sedimentary zone (the Arbuckle Group). The transducers are located in Alfalfa, Grant, and Payne Counties at distances of 48 to 140 km from the Pawnee earthquake. We observed coseismic fluid <span class="hlt">pressure</span> changes in all monitoring wells, indicating a large-scale poroelastic response in the Arbuckle. Two wells in Payne County lie in a zone of volumetric compression 48-52 km SSE of the rupture and experienced a co-seismic rise in fluid <span class="hlt">pressures</span> that we conclude was related to poroelastic rebound of the Arbuckle reservoir. We compare measurements of the <span class="hlt">pore</span>-fluid <span class="hlt">pressure</span> change to estimated values given by the product of the volumetric strain, a Skempton's coefficient of 0.33, and a Bulk modulus of 25 GPa for fractured granitic basement rocks. We explore the possibility that the small increase in <span class="hlt">pore</span>-fluid <span class="hlt">pressure</span> may increase the rate of seismicity in regions outside of the mainshock region. We test this hypothesis by supplementing the Oklahoma Geological Survey earthquake catalog by semi-automated detection smaller magnitude (<2.6 M) earthquakes on seismic stations that are located in the vicinity of the wells. Using the events that occur in the week before the mainshock (27 Aug to 3 Sep 2016) as the background seismicity rate and the estimated <span class="hlt">pore</span>-fluid <span class="hlt">pressure</span> increase, we use a rate-state model to predict the seismicity rate change in the week following the event. We then compare the model predictions to the observed seismicity in the week following the Pawnee earthquake</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4540421','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4540421"><span>Nanometer-Scale <span class="hlt">Pore</span> Characteristics of Lacustrine Shale, Songliao Basin, NE China</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Wang, Min; Yang, Jinxiu; Wang, Zhiwei; Lu, Shuangfang</p> <p>2015-01-01</p> <p>In shale, liquid hydrocarbons are accumulated mainly in nanometer-scale <span class="hlt">pores</span> or fractures, so the <span class="hlt">pore</span> types and PSDs (<span class="hlt">pore</span> size distributions) play a major role in the shale oil occurrence (free or absorbed state), amount of oil, and flow features. The <span class="hlt">pore</span> types and PSDs of marine shale have been well studied; however, research on lacustrine shale is rare, especially for shale in the oil generation window, although lacustrine shale is deposited widely around the world. To investigate the relationship between nanometer-scale <span class="hlt">pores</span> and oil occurrence in the lacustrine shale, 10 lacustrine shale core samples from Songliao Basin, NE China were analyzed. Analyses of these samples included geochemical measurements, SEM (scanning electron microscope) observations, low <span class="hlt">pressure</span> CO2 and N2 adsorption, and high-<span class="hlt">pressure</span> mercury injection experiments. Analysis results indicate that: (1) <span class="hlt">Pore</span> types in the lacustrine shale include inter-matrix <span class="hlt">pores</span>, intergranular <span class="hlt">pores</span>, organic matter <span class="hlt">pores</span>, and dissolution <span class="hlt">pores</span>, and these <span class="hlt">pores</span> are dominated by mesopores and micropores; (2) There is no apparent correlation between <span class="hlt">pore</span> volumes and clay content, however, a weak negative correlation is present between total <span class="hlt">pore</span> volume and carbonate content; (3) <span class="hlt">Pores</span> in lacustrine shale are well developed when the organic matter maturity (Ro) is >1.0% and the <span class="hlt">pore</span> volume is positively correlated with the TOC (total organic carbon) content. The statistical results suggest that oil in lacustrine shale mainly occurs in <span class="hlt">pores</span> with diameters larger than 40 nm. However, more research is needed to determine whether this minimum <span class="hlt">pore</span> diameter for oil occurrence in lacustrine shale is widely applicable. PMID:26285123</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/26285123','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26285123"><span>Nanometer-Scale <span class="hlt">Pore</span> Characteristics of Lacustrine Shale, Songliao Basin, NE China.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Wang, Min; Yang, Jinxiu; Wang, Zhiwei; Lu, Shuangfang</p> <p>2015-01-01</p> <p>In shale, liquid hydrocarbons are accumulated mainly in nanometer-scale <span class="hlt">pores</span> or fractures, so the <span class="hlt">pore</span> types and PSDs (<span class="hlt">pore</span> size distributions) play a major role in the shale oil occurrence (free or absorbed state), amount of oil, and flow features. The <span class="hlt">pore</span> types and PSDs of marine shale have been well studied; however, research on lacustrine shale is rare, especially for shale in the oil generation window, although lacustrine shale is deposited widely around the world. To investigate the relationship between nanometer-scale <span class="hlt">pores</span> and oil occurrence in the lacustrine shale, 10 lacustrine shale core samples from Songliao Basin, NE China were analyzed. Analyses of these samples included geochemical measurements, SEM (scanning electron microscope) observations, low <span class="hlt">pressure</span> CO2 and N2 adsorption, and high-<span class="hlt">pressure</span> mercury injection experiments. Analysis results indicate that: (1) <span class="hlt">Pore</span> types in the lacustrine shale include inter-matrix <span class="hlt">pores</span>, intergranular <span class="hlt">pores</span>, organic matter <span class="hlt">pores</span>, and dissolution <span class="hlt">pores</span>, and these <span class="hlt">pores</span> are dominated by mesopores and micropores; (2) There is no apparent correlation between <span class="hlt">pore</span> volumes and clay content, however, a weak negative correlation is present between total <span class="hlt">pore</span> volume and carbonate content; (3) <span class="hlt">Pores</span> in lacustrine shale are well developed when the organic matter maturity (Ro) is >1.0% and the <span class="hlt">pore</span> volume is positively correlated with the TOC (total organic carbon) content. The statistical results suggest that oil in lacustrine shale mainly occurs in <span class="hlt">pores</span> with diameters larger than 40 nm. However, more research is needed to determine whether this minimum <span class="hlt">pore</span> diameter for oil occurrence in lacustrine shale is widely applicable.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/19228030','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/19228030"><span>Bubble snap-off and capillary-back <span class="hlt">pressure</span> during counter-current spontaneous imbibition into model <span class="hlt">pores</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Unsal, Evren; Mason, Geoffrey; Morrow, Norman R; Ruth, Douglas W</p> <p>2009-04-09</p> <p>A previous paper (Unsal, E.; Mason, G.; Ruth, D. W.; Morrow, N. R. J. Colloid Interface Sci. 2007, 315, 200-209) reported experiments involving counter-current spontaneous imbibition into a model <span class="hlt">pore</span> system consisting of a rod in an angled slot covered by a glass plate. Such an arrangement gives two tubes with different cross-sections (both size and shape) with an interconnection through the gap between the rod and the plate. In the previous experiments, the wetting phase advanced in the small tube and nonwetting phase retreated in the large tube. No bubbles were formed. In this paper, we study experimentally and theoretically the formation of bubbles at the open end of the large tube and their subsequent snap-off. Such bubbles reduce the capillary back <span class="hlt">pressure</span> produced by the larger tube and can thus have an effect on the local rate of imbibition. In the model <span class="hlt">pore</span> system, the rod was either in contact with the glass, forming two independent tubes, or the rod was spaced from the glass to allow cross-flow between the tubes. For small gaps, there were three distinct menisci. The one with the highest curvature was between the rod and the plate. The next most highly curved was in the smaller tube, and the least highly curved meniscus was in the large tube and this was the tube from which the bubbles developed. The <span class="hlt">pressure</span> in the dead end of the system was recorded during imbibition. Once the bubble starts to form outside of the tube, the <span class="hlt">pressure</span> drops rapidly and then steadies. After the bubble snaps off, the <span class="hlt">pressure</span> rises to almost the initial value and stays essentially constant until the next bubble starts to form. After snap-off, the meniscus in the large tube appears to invade the large tube for some distance. The snap-off is the result of capillary instability; it takes place significantly inside the large tube with flow of wetting phase moving in the angular corners. As imbibition into the small tube progresses, the rate of imbibition decreases and the</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017EGUGA..1914943K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017EGUGA..1914943K"><span>Impact of fluid injection velocity on CO2 saturation and <span class="hlt">pore</span> <span class="hlt">pressure</span> in porous sandstone</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kitamura, Keigo; Honda, Hiroyuki; Takaki, Shinnosuke; Imasato, Mitsunori; Mitani, Yasuhiro</p> <p>2017-04-01</p> <p>The elucidation of CO2 behavior in sandstone is an essential issue to understand the fate of injecting CO2 in reservoirs. Injected CO2 invades <span class="hlt">pore</span> spaces and replaces with resident brine and forms complex two-phase flow with brine. It is considered that this complex CO2 flow arises CO2 saturation (SCO_2)and <span class="hlt">pore</span> fluid <span class="hlt">pressure</span>(Pp) and makes various types of CO2 distribution pattern in <span class="hlt">pore</span> space. The estimation of SCO_2 in the reservoir is one of important task in CCS projects. Fluid <span class="hlt">pressure</span> (Pp) is also important to estimate the integrity of CO2 reservoir and overlying cap rocks. Generally, elastic waves are used to monitor the changes of SCO_2. Previous experimental and theoretical studies indicated that SCO_2 and Pp are controlled by the fluid velocity (flow rate) of invaded phase. In this study, we conducted the CO2 injection test for Berea sandstone (φ=18.1{%}) under deep CO2 reservoir conditions (confining <span class="hlt">pressure</span>: 20MPa; temperature: 40 rC). We try to estimate the changes of SCO_2 and Pp with changing CO2 injection rate (FR) from 10 to 5000 μ l/min for Berea sandstone. P-wave velocities (Vp) are also measured during CO2 injection test and used to investigate the relationships between SCO2 and these geophysical parameters. We set three Vp-measurement channels (ch.1, ch2 and ch.3 from the bottom) monitor the CO2 behavior. The result shows step-wise SCO_2 changes with increasing FR from 9 to 25 {%} in low-FR condition (10-500 μ l/min). Vp also shows step wise change from ch1 to ch.3. The lowermost channel (ch.1) indicates that Vp-reduction stops around 4{%} at 10μ m/min condition. However, ch.3 changes slightly from 4{%} at 10 μ l/min to 5{%} at 100 μ l/min. On the other hand, differential Pp (Δ P) dose not shows obvious changes from 10kPa to 30kPa. Over 1000 μ l/min, SCO_2 increases from 35 to 47 {%}. Vp of all channels show slight reductions and Vp-reductions reach constant values as 8{%}, 6{%} and 8{%}, respectively at 5000{}μ l/min. On the other</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/biblio/1327095-predicting-stress-vs-strain-behaviors-thin-walled-high-pressure-die-cast-magnesium-alloy-actual-pore-distribution','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/1327095-predicting-stress-vs-strain-behaviors-thin-walled-high-pressure-die-cast-magnesium-alloy-actual-pore-distribution"><span>Predicting Stress vs. Strain Behaviors of Thin-Walled High <span class="hlt">Pressure</span> Die Cast Magnesium Alloy with Actual <span class="hlt">Pore</span> Distribution</span></a></p> <p><a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a></p> <p>Choi, Kyoo Sil; Barker, Erin; Cheng, Guang</p> <p>2016-01-06</p> <p>In this paper, a three-dimensional (3D) microstructure-based finite element modeling method (i.e., extrinsic modeling method) is developed, which can be used in examining the effects of porosity on the ductility/fracture of Mg castings. For this purpose, AM60 Mg tensile samples were generated under high-<span class="hlt">pressure</span> die-casting in a specially-designed mold. Before the tensile test, the samples were CT-scanned to obtain the <span class="hlt">pore</span> distributions within the samples. 3D microstructure-based finite element models were then developed based on the obtained actual <span class="hlt">pore</span> distributions of the gauge area. The input properties for the matrix material were determined by fitting the simulation result to themore » experimental result of a selected sample, and then used for all the other samples’ simulation. The results show that the ductility and fracture locations predicted from simulations agree well with the experimental results. This indicates that the developed 3D extrinsic modeling method may be used to examine the influence of various aspects of <span class="hlt">pore</span> sizes/distributions as well as intrinsic properties (i.e., matrix properties) on the ductility/fracture of Mg castings.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/pages/biblio/1390383-differences-soluble-organic-carbon-chemistry-pore-waters-sampled-from-different-pore-size-domains','SCIGOV-DOEP'); return false;" href="https://www.osti.gov/pages/biblio/1390383-differences-soluble-organic-carbon-chemistry-pore-waters-sampled-from-different-pore-size-domains"><span>Differences in soluble organic carbon chemistry in <span class="hlt">pore</span> waters sampled from different <span class="hlt">pore</span> size domains</span></a></p> <p><a target="_blank" href="http://www.osti.gov/pages">DOE PAGES</a></p> <p>Bailey, Vanessa L.; Smith, A. P.; Tfaily, Malak; ...</p> <p>2017-01-11</p> <p>Spatial isolation of soil organic carbon (SOC) in different sized <span class="hlt">pores</span> may be a mechanism by which otherwise labile carbon (C) could be protected in soils. When soil water content increases, the hydrologic connectivity of soil <span class="hlt">pores</span> also increases, allowing greater transport of SOC and other resources from protected locations, to microbially colonized locations more favorable to decomposition. The heterogeneous distribution of specialized decomposers, C, and other resources throughout the soil indicates that the metabolism or persistence of soil C compounds is highly dependent on short-distance transport processes. The objective of this research was to characterize the complexity of Cmore » in <span class="hlt">pore</span> waters held at weak and strong water tensions (effectively soil solution held behind coarse- and fine-<span class="hlt">pore</span> throats, respectively) and evaluate the microbial decomposability of these <span class="hlt">pore</span> waters. We saturated intact soil cores and extracted <span class="hlt">pore</span> waters with increasing suction <span class="hlt">pressures</span> to sequentially sample <span class="hlt">pore</span> waters from increasingly fine <span class="hlt">pore</span> domains. Ultrahigh resolution mass spectrometry of the SOC was used to profile the major biochemical classes (i.e., lipids, proteins, lignin, carbohydrates, and condensed aromatics) of compounds present in the <span class="hlt">pore</span> waters; some of these samples were then used as substrates for growth of Cellvibrio japonicus (DSMZ 16018), Streptomyces cellulosae (ATCC ® 25439™), and Trichoderma reseei (QM6a) in 7 day incubations. The soluble C in finer <span class="hlt">pores</span> was more complex than the soluble C in coarser <span class="hlt">pores</span>, and the incubations revealed that the more complex C in these fine <span class="hlt">pores</span> is not recalcitrant. The decomposition of this complex C led to greater losses of C through respiration than the simpler C from coarser <span class="hlt">pore</span> waters. Our research suggests that soils that experience repeated cycles of drying and wetting may be accompanied by repeated cycles of increased CO 2 fluxes that are driven by i) the transport of C from protected pools</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/biblio/1390383-differences-soluble-organic-carbon-chemistry-pore-waters-sampled-from-different-pore-size-domains','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/1390383-differences-soluble-organic-carbon-chemistry-pore-waters-sampled-from-different-pore-size-domains"><span>Differences in soluble organic carbon chemistry in <span class="hlt">pore</span> waters sampled from different <span class="hlt">pore</span> size domains</span></a></p> <p><a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a></p> <p>Bailey, Vanessa L.; Smith, A. P.; Tfaily, Malak</p> <p></p> <p>Spatial isolation of soil organic carbon (SOC) in different sized <span class="hlt">pores</span> may be a mechanism by which otherwise labile carbon (C) could be protected in soils. When soil water content increases, the hydrologic connectivity of soil <span class="hlt">pores</span> also increases, allowing greater transport of SOC and other resources from protected locations, to microbially colonized locations more favorable to decomposition. The heterogeneous distribution of specialized decomposers, C, and other resources throughout the soil indicates that the metabolism or persistence of soil C compounds is highly dependent on short-distance transport processes. The objective of this research was to characterize the complexity of Cmore » in <span class="hlt">pore</span> waters held at weak and strong water tensions (effectively soil solution held behind coarse- and fine-<span class="hlt">pore</span> throats, respectively) and evaluate the microbial decomposability of these <span class="hlt">pore</span> waters. We saturated intact soil cores and extracted <span class="hlt">pore</span> waters with increasing suction <span class="hlt">pressures</span> to sequentially sample <span class="hlt">pore</span> waters from increasingly fine <span class="hlt">pore</span> domains. Ultrahigh resolution mass spectrometry of the SOC was used to profile the major biochemical classes (i.e., lipids, proteins, lignin, carbohydrates, and condensed aromatics) of compounds present in the <span class="hlt">pore</span> waters; some of these samples were then used as substrates for growth of Cellvibrio japonicus (DSMZ 16018), Streptomyces cellulosae (ATCC ® 25439™), and Trichoderma reseei (QM6a) in 7 day incubations. The soluble C in finer <span class="hlt">pores</span> was more complex than the soluble C in coarser <span class="hlt">pores</span>, and the incubations revealed that the more complex C in these fine <span class="hlt">pores</span> is not recalcitrant. The decomposition of this complex C led to greater losses of C through respiration than the simpler C from coarser <span class="hlt">pore</span> waters. Our research suggests that soils that experience repeated cycles of drying and wetting may be accompanied by repeated cycles of increased CO 2 fluxes that are driven by i) the transport of C from protected pools</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/17389696','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/17389696"><span>Obesity is the major determinant of the <span class="hlt">abnormalities</span> in blood <span class="hlt">pressure</span> found in young women with the polycystic ovary syndrome.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Luque-Ramírez, Manuel; Alvarez-Blasco, Francisco; Mendieta-Azcona, Covadonga; Botella-Carretero, José I; Escobar-Morreale, Héctor F</p> <p>2007-06-01</p> <p>Obesity and insulin resistance predispose patients with the polycystic ovary syndrome (PCOS) to <span class="hlt">abnormalities</span> in blood <span class="hlt">pressure</span> regulation. Our objective was to evaluate the impact of obesity on the blood <span class="hlt">pressure</span> profiles of PCOS patients. PATIENTS, SETTING, AND DESIGN: Thirty-six PCOS patients and 20 healthy women participated in a case-control study at an academic hospital. We conducted ambulatory blood <span class="hlt">pressure</span> monitoring and office blood <span class="hlt">pressure</span> determinations. Hypertension (defined as increased office blood <span class="hlt">pressure</span> confirmed by ambulatory blood <span class="hlt">pressure</span> monitoring or by masked hypertension) was present in 12 PCOS patients and eight controls (P = 0.618). No differences between patients and controls were found in office and ambulatory blood <span class="hlt">pressure</span> monitoring values and heart rate, yet the nocturnal decrease in mean blood <span class="hlt">pressure</span> was smaller in patients (P = 0.038). Obese women (13 patients and eight controls) had increased frequencies of office hypertension (29% compared with 3% in lean plus overweight women, P = 0.005), increased diastolic (P = 0.009) and mean (P = 0.015) office blood <span class="hlt">pressure</span> values, and increased heart rate values during the daytime (P = 0.038), nighttime (P = 0.002), and 24-h (P = 0.009) periods, independently of having PCOS or not. The frequency of a nocturnal nondipper pattern was 62% in obese PCOS patients, compared with 26% in lean plus overweight PCOS patients (P = 0.036) and 25% in obese and in lean plus overweight controls. <span class="hlt">Abnormalities</span> in the regulation of blood <span class="hlt">pressure</span> are common in young women with PCOS, yet, with the exception of the nondipper pattern, these <span class="hlt">abnormalities</span> result from the frequent association of this syndrome with obesity.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4876920','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4876920"><span><span class="hlt">Poring</span> over two-<span class="hlt">pore</span> channel <span class="hlt">pore</span> mutants</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Penny, Christopher J.; Patel, Sandip</p> <p>2016-01-01</p> <p>Two-<span class="hlt">pore</span> channels are members of the voltage-gated ion channel superfamily. They localise to the endolysosomal system and are likely targets for the Ca2+ mobilising messenger NAADP. In this brief review, we relate mutagenesis of the TPC <span class="hlt">pore</span> to a recently published homology model and discuss how <span class="hlt">pore</span> mutants are informing us of TPC function. Molecular physiology of these ubiquitous proteins is thus emerging. PMID:27226934</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1994JMEP....3..419K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1994JMEP....3..419K"><span>An investigation of <span class="hlt">pore</span> cracking in titanium welds</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Khaled, Z.</p> <p>1994-06-01</p> <p>Two welded Ti-6A1- 4V <span class="hlt">pressure</span> vessels leaked prematurely in service. The leaks were caused by cracks emanating from weld porosity. The cracks originated during fabrication, with subsequent growth in serv-ice leading to the formation of the leak paths. <span class="hlt">Pore</span> cracking is thought to be caused by a mechanism that involves both sustained- load and cyclic contributions, with the former being the more prominent. It is shown that the tendency for cracking is influenced by <span class="hlt">pore</span> position and that <span class="hlt">pore</span> size is not a deciding factor in that regard. The factors that govern <span class="hlt">pore</span> cracking are discussed, and the possible role of inter-stitial embrittlement is assessed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1994JMEP....3...21K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1994JMEP....3...21K"><span>An investigation of <span class="hlt">pore</span> cracking in titanium welds</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Khaled, T.</p> <p>1994-02-01</p> <p>Two welded Ti-6A1-4V <span class="hlt">pressure</span> vessels leaked prematurely in service. The leaks were caused by cracks emanating from weld porosity. The cracks originated during fabrication, with subsequent growth in service leading to the formation of the leak paths. <span class="hlt">Pore</span> cracking is thought to be caused by a mechanism that involves both sustained-load and cyclic contributions, with the former being the more prominent. It is shown that the tendency for cracking is influenced by <span class="hlt">pore</span> position and that <span class="hlt">pore</span> size is not a deciding factor in that regard. The factors that govern <span class="hlt">pore</span> cracking are discussed, and the possible role of interstitial embrittlement is assessed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/27085076','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/27085076"><span>Importance of Calibration Method in Central Blood <span class="hlt">Pressure</span> for Cardiac Structural <span class="hlt">Abnormalities</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Negishi, Kazuaki; Yang, Hong; Wang, Ying; Nolan, Mark T; Negishi, Tomoko; Pathan, Faraz; Marwick, Thomas H; Sharman, James E</p> <p>2016-09-01</p> <p>Central blood <span class="hlt">pressure</span> (CBP) independently predicts cardiovascular risk, but calibration methods may affect accuracy of central systolic blood <span class="hlt">pressure</span> (CSBP). Standard central systolic blood <span class="hlt">pressure</span> (Stan-CSBP) from peripheral waveforms is usually derived with calibration using brachial SBP and diastolic BP (DBP). However, calibration using oscillometric mean arterial <span class="hlt">pressure</span> (MAP) and DBP (MAP-CSBP) is purported to provide more accurate representation of true invasive CSBP. This study sought to determine which derived CSBP could more accurately discriminate cardiac structural <span class="hlt">abnormalities</span>. A total of 349 community-based patients with risk factors (71±5years, 161 males) had CSBP measured by brachial oscillometry (Mobil-O-Graph, IEM GmbH, Stolberg, Germany) using 2 calibration methods: MAP-CSBP and Stan-CSBP. Left ventricular hypertrophy (LVH) and left atrial dilatation (LAD) were measured based on standard guidelines. MAP-CSBP was higher than Stan-CSBP (149±20 vs. 128±15mm Hg, P < 0.0001). Although they were modestly correlated (rho = 0.74, P < 0.001), the Bland-Altman plot demonstrated a large bias (21mm Hg) and limits of agreement (24mm Hg). In receiver operating characteristic (ROC) curve analyses, MAP-CSBP significantly better discriminated LVH compared with Stan-CSBP (area under the curve (AUC) 0.66 vs. 0.59, P = 0.0063) and brachial SBP (0.62, P = 0.027). Continuous net reclassification improvement (NRI) (P < 0.001) and integrated discrimination improvement (IDI) (P < 0.001) corroborated superior discrimination of LVH by MAP-CSBP. Similarly, MAP-CSBP better distinguished LAD than Stan-CSBP (AUC 0.63 vs. 0.56, P = 0.005) and conventional brachial SBP (0.58, P = 0.006), whereas Stan-CSBP provided no better discrimination than conventional brachial BP (P = 0.09). CSBP is calibration dependent and when oscillometric MAP and DBP are used, the derived CSBP is a better discriminator for cardiac structural <span class="hlt">abnormalities</span>. © American Journal of Hypertension</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://pubs.er.usgs.gov/publication/70018836','USGSPUBS'); return false;" href="https://pubs.er.usgs.gov/publication/70018836"><span>Postseismic rebound in fault step-overs caused by <span class="hlt">pore</span> fluid flow</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Peltzer, G.; Rosen, P.; Rogez, F.; Hudnut, K.</p> <p>1996-01-01</p> <p>Near-field strain induced by large crustal earthquakes results in changes in <span class="hlt">pore</span> fluid <span class="hlt">pressure</span> that dissipate with time and produce surface deformation. Synthetic aperture radar (SAR) interferometry revealed several centimeters of postseismic uplift in pull-apart structures and subsidence in a compressive jog along the Landers, California, 1992 earthquake surface rupture, with a relaxation time of 270 ?? 45 days. Such a postseismic rebound may be explained by the transition of the Poisson's ratio of the deformed volumes of rock from undrained to drained conditions as <span class="hlt">pore</span> fluid flow allows <span class="hlt">pore</span> <span class="hlt">pressure</span> to return to hydrostatic equilibrium.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://pubs.er.usgs.gov/publication/70028632','USGSPUBS'); return false;" href="https://pubs.er.usgs.gov/publication/70028632"><span>Methods for <span class="hlt">pore</span> water extraction from unsaturated zone tuff, Yucca Mountain, Nevada</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Scofield, K.M.</p> <p>2006-01-01</p> <p>Assessing the performance of the proposed high-level radioactive waste repository at Yucca Mountain, Nevada, requires an understanding of the chemistry of the water that moves through the host rock. The uniaxial compression method used to extract <span class="hlt">pore</span> water from samples of tuffaceous borehole core was successful only for nonwelded tuff. An ultracentrifugation method was adopted to extract <span class="hlt">pore</span> water from samples of the densely welded tuff of the proposed repository horizon. Tests were performed using both methods to determine the efficiency of <span class="hlt">pore</span> water extraction and the potential effects on <span class="hlt">pore</span> water chemistry. Test results indicate that uniaxial compression is most efficient for extracting <span class="hlt">pore</span> water from nonwelded tuff, while ultracentrifugation is more successful in extracting <span class="hlt">pore</span> water from densely welded tuff. <span class="hlt">Pore</span> water splits collected from a single nonwelded tuff core during uniaxial compression tests have shown changes in <span class="hlt">pore</span> water chemistry with increasing <span class="hlt">pressure</span> for calcium, chloride, sulfate, and nitrate. <span class="hlt">Pore</span> water samples collected from the intermediate <span class="hlt">pressure</span> ranges should prevent the influence of re-dissolved, evaporative salts and the addition of ion-deficient water from clays and zeolites. Chemistry of <span class="hlt">pore</span> water splits from welded and nonwelded tuffs using ultracentrifugation indicates that there is no substantial fractionation of solutes.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/21819070','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/21819070"><span>Cavitation and <span class="hlt">pore</span> blocking in nanoporous glasses.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Reichenbach, C; Kalies, G; Enke, D; Klank, D</p> <p>2011-09-06</p> <p>In gas adsorption studies, porous glasses are frequently referred to as model materials for highly disordered mesopore systems. Numerous works suggest that an accurate interpretation of physisorption isotherms requires a complete understanding of network effects upon adsorption and desorption, respectively. The present article deals with nitrogen and argon adsorption at different temperatures (77 and 87 K) performed on a series of novel nanoporous glasses (NPG) with different mean <span class="hlt">pore</span> widths. NPG samples contain smaller mesopores and significantly higher microporosity than porous Vycor glass or controlled <span class="hlt">pore</span> glass. Since the mean <span class="hlt">pore</span> width of NPG can be tuned sensitively, the evolution of adsorption characteristics with respect to a broadening <span class="hlt">pore</span> network can be investigated starting from the narrowest nanopore width. With an increasing mean <span class="hlt">pore</span> width, a H2-type hysteresis develops gradually which finally transforms into a H1-type. In this connection, a transition from a cavitation-induced desorption toward desorption controlled by <span class="hlt">pore</span> blocking can be observed. Furthermore, we find concrete hints for a <span class="hlt">pore</span> size dependence of the relative <span class="hlt">pressure</span> of cavitation in highly disordered <span class="hlt">pore</span> systems. By comparing nitrogen and argon adsorption, a comprehensive insight into adsorption mechanisms in novel disordered materials is provided. © 2011 American Chemical Society</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_6");'>6</a></li> <li><a href="#" onclick='return showDiv("page_7");'>7</a></li> <li class="active"><span>8</span></li> <li><a href="#" onclick='return showDiv("page_9");'>9</a></li> <li><a href="#" onclick='return showDiv("page_10");'>10</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_8 --> <div id="page_9" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_7");'>7</a></li> <li><a href="#" onclick='return showDiv("page_8");'>8</a></li> <li class="active"><span>9</span></li> <li><a href="#" onclick='return showDiv("page_10");'>10</a></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="161"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010EGUGA..1215286L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010EGUGA..1215286L"><span>Effects Of Bedrock Shape And Hillslope Gradient On The <span class="hlt">Pore</span>-Water <span class="hlt">Pressure</span> Development: Implication For Slope Stability</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Lanni, Cristiano; McDonnell, Jeff</p> <p>2010-05-01</p> <p>Shallow Landslides are one of the most important causes of loss of human life and socio-economic damage related to the hydro-geological risk issues. The danger of these phenomena is related to their speed of development, the diffculty of foreseeing their location, and the high density of individual phenomena, whose downhill trajectories have a relevant probability of interfering with urbanized areas. Research activity on precipitation-induced landslides has focused mainly on developing predictive understanding of where and when landslides are likely to occur. Nevertheless, some major aspects that may be related to activation of landslides have been poorly investigated. For instance, landslide susceptibility zones are generally predicted assuming constant thickness of soil over an impervious bedrock layer. Nevertheless, recent studies showed subsurface topography could be a first order control for subsurface water-flow dynamics, because of the effects of its own irregular shape. Tromp-van Meerveld and McDonnell (2006) argued that connectivity of patches of transient saturation were a necessary prerequisite for exceeding the rainfall threshold necessary to drive lateral flow. Connectivity - "how the hillslope architecture controls the filling and spilling of isolated patches of saturation" (Hopp and McDonnell, 2009) - appears to be a possible unifying concept and theoretical platform for moving hillslope and watershed hydrology forward. Connectivity could also have important implications on triggering of shallow landslides, because the particular shape of bedrock may limit the water-flow downhill. Here we present a number of virtual numerical experiments performed to investigate the role of bedrock shape and hillslope gradient on <span class="hlt">pore</span>-water <span class="hlt">pressure</span> development. On this purpose, our test is represented by the subsurface topography of the Panola Experiment Hillslope (PEH). That is because scientific literature on PEH provides substantial documentation about the role</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://pubs.er.usgs.gov/publication/70185448','USGSPUBS'); return false;" href="https://pubs.er.usgs.gov/publication/70185448"><span>Measurement of variation in soil solute tracer concentration across a range of effective <span class="hlt">pore</span> sizes</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Harvey, Judson W.</p> <p>1993-01-01</p> <p>Solute transport concepts in soil are based on speculation that solutes are distributed nonuniformly within large and small <span class="hlt">pores</span>. Solute concentrations have not previously been measured across a range of <span class="hlt">pore</span> sizes and examined in relation to soil hydrological properties. For this study, modified <span class="hlt">pressure</span> cells were used to measure variation in concentration of a solute tracer across a range of <span class="hlt">pore</span> sizes. Intact cores were removed from the site of a field tracer experiment, and soil water was eluted from 10 or more discrete classes of <span class="hlt">pore</span> size. Simultaneous changes in water content and unsaturated hydraulic conductivity were determined on cores using standard <span class="hlt">pressure</span> cell techniques. Bromide tracer concentration varied by as much as 100% across the range of <span class="hlt">pore</span> sizes sampled. Immediately following application of the bromide tracer on field plots, bromide was most concentrated in the largest <span class="hlt">pores</span>; concentrations were lower in <span class="hlt">pores</span> of progressively smaller sizes. After 27 days, bromide was most dilute in the largest <span class="hlt">pores</span> and concentrations were higher in the smaller <span class="hlt">pores</span>. A sharp, threefold decrease in specific water capacity during elution indicated separation of two major <span class="hlt">pore</span> size classes at a <span class="hlt">pressure</span> of 47 cm H2O and a corresponding effective <span class="hlt">pore</span> diameter of 70 μm. Variation in tracer concentration, on the other hand, was spread across the entire range of <span class="hlt">pore</span> sizes investigated in this study. A two-porosity characterization of the transport domain, based on water retention criteria, only broadly characterized the pattern of variation in tracer concentration across <span class="hlt">pore</span> size classes during transport through a macroporous soil.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/servlets/purl/840448','SCIGOV-STC'); return false;" href="https://www.osti.gov/servlets/purl/840448"><span>Nanoscale <span class="hlt">Pore</span> Imaging and <span class="hlt">Pore</span> Scale Fluid Flow Modeling in Chalk</span></a></p> <p><a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a></p> <p>Tomutsa, Liviu; Silin, Dmitriy</p> <p>2004-08-19</p> <p>For many rocks of high economic interest such as chalk, diatomite, tight gas sands or coal, nanometer scale resolution is needed to resolve the 3D-<span class="hlt">pore</span> structure, which controls the flow and trapping of fluids in the rocks. Such resolutions cannot be achieved with existing tomographic technologies. A new 3D imaging method, based on serial sectioning and using the Focused Ion Beam (FIB) technology has been developed. FIB allows for the milling of layers as thin as 10 nanometers by using accelerated Ga+ ions to sputter atoms from the sample surface. After each milling step, as a new surface is exposed,more » a 2D image of this surface is generated. Next, the 2D images are stacked to reconstruct the 3D <span class="hlt">pore</span> or grain structure. Resolutions as high as 10 nm are achievable using such a technique. A new robust method of <span class="hlt">pore</span>-scale fluid flow modeling has been developed and applied to sandstone and chalk samples. The method uses direct morphological analysis of the <span class="hlt">pore</span> space to characterize the petrophysical properties of diverse formations. Not only petrophysical properties (porosity, permeability, relative permeability and capillary <span class="hlt">pressures</span>) can be computed but also flow processes, such as those encountered in various IOR approaches, can be simulated. Petrophysical properties computed with the new method using the new FIB data will be presented. Present study is a part of the development of an Electronic Core Laboratory at LBNL/UCB.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/19203762','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/19203762"><span>The effects of chain length, embedded polar groups, <span class="hlt">pressure</span>, and <span class="hlt">pore</span> shape on structure and retention in reversed-phase liquid chromatography: molecular-level insights from Monte Carlo simulations.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Rafferty, Jake L; Siepmann, J Ilja; Schure, Mark R</p> <p>2009-03-20</p> <p>Particle-based simulations using the configurational-bias and Gibbs ensemble Monte Carlo techniques are carried out to probe the effects of various chromatographic parameters on bonded-phase chain conformation, solvent penetration, and retention in reversed-phase liquid chromatography (RPLC). Specifically, we investigate the effects due to the length of the bonded-phase chains (C(18), C(8), and C(1)), the inclusion of embedded polar groups (amide and ether) near the base of the bonded-phase chains, the column <span class="hlt">pressure</span> (1, 400, and 1000 atm), and the <span class="hlt">pore</span> shape (planar slit <span class="hlt">pore</span> versus cylindrical <span class="hlt">pore</span> with a 60A diameter). These simulations utilize a bonded-phase coverage of 2.9 micromol/m(2)and a mobile phase containing methanol at a molfraction of 33% (about 50% by volume). The simulations show that chain length, embedded polar groups, and <span class="hlt">pore</span> shape significantly alter structural and retentive properties of the model RPLC system, whereas the column <span class="hlt">pressure</span> has a relatively small effect. The simulation results are extensively compared to retention measurements. A molecular view of the RPLC retention mechanism emerges that is more complex than can be inferred from thermodynamic measurements.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://pubs.er.usgs.gov/publication/70023641','USGSPUBS'); return false;" href="https://pubs.er.usgs.gov/publication/70023641"><span>New general <span class="hlt">pore</span> size distribution model by classical thermodynamics application: Activated carbon</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Lordgooei, M.; Rood, M.J.; Rostam-Abadi, M.</p> <p>2001-01-01</p> <p>A model is developed using classical thermodynamics to characterize <span class="hlt">pore</span> size distributions (PSDs) of materials containing micropores and mesopores. The thermal equation of equilibrium adsorption (TEEA) is used to provide thermodynamic properties and relate the relative <span class="hlt">pore</span> filling <span class="hlt">pressure</span> of vapors to the characteristic <span class="hlt">pore</span> energies of the adsorbent/adsorbate system for micropore sizes. <span class="hlt">Pore</span> characteristic energies are calculated by averaging of interaction energies between adsorbate molecules and adsorbent <span class="hlt">pore</span> walls as well as considering adsorbate-adsorbate interactions. A modified Kelvin equation is used to characterize mesopore sizes by considering variation of the adsorbate surface tension and by excluding the adsorbed film layer for the <span class="hlt">pore</span> size. The modified-Kelvin equation provides similar <span class="hlt">pore</span> filling <span class="hlt">pressures</span> as predicted by density functional theory. Combination of these models provides a complete PSD of the adsorbent for the micropores and mesopores. The resulting PSD is compared with the PSDs from Jaroniec and Choma and Horvath and Kawazoe models as well as a first-order approximation model using Polanyi theory. The major importance of this model is its basis on classical thermodynamic properties, less simplifying assumptions in its derivation compared to other methods, and ease of use.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014AGUFM.B11B0013J','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014AGUFM.B11B0013J"><span>Characterization of Gas-Hydrate Sediment: In Situ Evaluation of Hydrate Saturation in <span class="hlt">Pores</span> of <span class="hlt">Pressured</span> Sedimental Samples</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Jin, Y.; Konno, Y.; Kida, M.; Nagao, J.</p> <p>2014-12-01</p> <p>Hydrate saturation of gas-hydrate bearing sediment is a key of gas production from natural gas-hydrate reservoir. Developable natural gas-hydrates by conventional gas/oil production apparatus almost exist in unconsolidated sedimental layer. Generally, hydrate saturations of sedimental samples are directly estimated by volume of gas generated from dissociation of gas hydrates in <span class="hlt">pore</span> spaces, porosity data and volume of the sediments. Furthermore, hydrate saturation can be also assessed using velocity of P-wave through sedimental samples. Nevertheless, hydrate saturation would be changed by morphological variations (grain-coating, cementing and <span class="hlt">pore</span>-filling model) of gas hydrates in <span class="hlt">pore</span> spaces. Jin et al.[1,2] recently observed the O-H stretching bands of H2O molecules of methane hydrate in porous media using an attenuated total reflection IR (ATR-IR) spectra. They observed in situ hydrate formation/dissociation process in sandy samples (Tohoku Keisya number 8, grain size of ca. 110 μm). In this presentation, we present IR spectroscopy approach to in situ evaluation of hydrate saturation of <span class="hlt">pressured</span> gas-hydrate sediments. This work was supported by funding from the Research Consortium for Methane Hydrate Resources in Japan (MH21 Research Consortium) planned by the Ministry of Economy, Trade and Industry (METI), Japan. [1] Jin, Y.; Konno, Y.; Nagao, J. Energy Fules, 2012, 26, 2242-2247. [2] Jin, Y.; Oyama, H.; Nagao, J. Jpn. J. Appl. Phys. 2009, 48, No. 108001.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018MMTA...49..563Y','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018MMTA...49..563Y"><span><span class="hlt">Pore</span> Formation During Solidification of Aluminum: Reconciliation of Experimental Observations, Modeling Assumptions, and Classical Nucleation Theory</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Yousefian, Pedram; Tiryakioğlu, Murat</p> <p>2018-02-01</p> <p>An in-depth discussion of <span class="hlt">pore</span> formation is presented in this paper by first reinterpreting in situ observations reported in the literature as well as assumptions commonly made to model <span class="hlt">pore</span> formation in aluminum castings. The physics of <span class="hlt">pore</span> formation is reviewed through theoretical fracture <span class="hlt">pressure</span> calculations based on classical nucleation theory for homogeneous and heterogeneous nucleation, with and without dissolved gas, i.e., hydrogen. Based on the fracture <span class="hlt">pressure</span> for aluminum, critical <span class="hlt">pore</span> size and the corresponding probability of vacancies clustering to form that size have been calculated using thermodynamic data reported in the literature. Calculations show that it is impossible for a <span class="hlt">pore</span> to nucleate either homogeneously or heterogeneously in aluminum, even with dissolved hydrogen. The formation of <span class="hlt">pores</span> in aluminum castings can only be explained by inflation of entrained surface oxide films (bifilms) under reduced <span class="hlt">pressure</span> and/or with dissolved gas, which involves only growth, avoiding any nucleation problem. This mechanism is consistent with the reinterpretations of in situ observations as well as the assumptions made in the literature to model <span class="hlt">pore</span> formation.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016AGUFMMR44A..03H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016AGUFMMR44A..03H"><span>Dual <span class="hlt">pore</span>-connectivity and flow-paths affect shale hydrocarbon production</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Hayman, N. W.; Daigle, H.; Kelly, E. D.; Milliken, K. L.; Jiang, H.</p> <p>2016-12-01</p> <p>Aided with integrated characterization approaches of droplet contact angle measurement, mercury intrusion capillary <span class="hlt">pressure</span>, low-<span class="hlt">pressure</span> gas physisorption, scanning electron microscopy, and small angle neutron scattering, we have systematically studied how <span class="hlt">pore</span> connectivity and wettability are associated with mineral and organic matter phases of shales (Barnett, Bakken, Eagle Ford), as well as their influence on macroscopic fluid flow and hydrocarbon movement, from the following complementary tests: vacuum saturation with vacuum-pulling on dry shale followed with tracer introduction and high-<span class="hlt">pressure</span> intrusion, tracer diffusion into fluid-saturated shale, fluid and tracer imbibition into partially-saturated shale, and Wood's metal intrusion followed with imaging and elemental mapping. The first three tests use tracer-bearing fluids (hydrophilic API brine and hydrophobic n-decane) fluids with a suite of wettability tracers of different sizes and reactivities developed in our laboratory. These innovative and integrated approaches indicate a Dalmatian wettability behavior at a scale of microns, limited connectivity (<500 microns from shale sample edge) shale <span class="hlt">pores</span>, and disparity of well-connected hydrophobic <span class="hlt">pore</span> network ( 10 nm) and sparsely connected hydrophilic <span class="hlt">pore</span> systems (>50-100 nm), which is linked to the steep initial decline and low overall recovery because of the limited connection of hydrocarbon molecules in the shale matrix to the stimulated fracture network.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017AGUFMMR44A..03H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017AGUFMMR44A..03H"><span>Dual <span class="hlt">pore</span>-connectivity and flow-paths affect shale hydrocarbon production</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Hu, Q.; Barber, T.; Zhang, Y.; Md Golam, K.</p> <p>2017-12-01</p> <p>Aided with integrated characterization approaches of droplet contact angle measurement, mercury intrusion capillary <span class="hlt">pressure</span>, low-<span class="hlt">pressure</span> gas physisorption, scanning electron microscopy, and small angle neutron scattering, we have systematically studied how <span class="hlt">pore</span> connectivity and wettability are associated with mineral and organic matter phases of shales (Barnett, Bakken, Eagle Ford), as well as their influence on macroscopic fluid flow and hydrocarbon movement, from the following complementary tests: vacuum saturation with vacuum-pulling on dry shale followed with tracer introduction and high-<span class="hlt">pressure</span> intrusion, tracer diffusion into fluid-saturated shale, fluid and tracer imbibition into partially-saturated shale, and Wood's metal intrusion followed with imaging and elemental mapping. The first three tests use tracer-bearing fluids (hydrophilic API brine and hydrophobic n-decane) fluids with a suite of wettability tracers of different sizes and reactivities developed in our laboratory. These innovative and integrated approaches indicate a Dalmatian wettability behavior at a scale of microns, limited connectivity (<500 microns from shale sample edge) shale <span class="hlt">pores</span>, and disparity of well-connected hydrophobic <span class="hlt">pore</span> network ( 10 nm) and sparsely connected hydrophilic <span class="hlt">pore</span> systems (>50-100 nm), which is linked to the steep initial decline and low overall recovery because of the limited connection of hydrocarbon molecules in the shale matrix to the stimulated fracture network.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/29626810','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/29626810"><span>Generation of nanobubbles by ceramic membrane filters: The dependence of bubble size and zeta potential on surface coating, <span class="hlt">pore</span> size and injected gas <span class="hlt">pressure</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Ahmed, Ahmed Khaled Abdella; Sun, Cuizhen; Hua, Likun; Zhang, Zhibin; Zhang, Yanhao; Zhang, Wen; Marhaba, Taha</p> <p>2018-07-01</p> <p>Generation of gaseous nanobubbles (NBs) by simple, efficient, and scalable methods is critical for industrialization and applications of nanobubbles. Traditional generation methods mainly rely on hydrodynamic, acoustic, particle, and optical cavitation. These generation processes render issues such as high energy consumption, non-flexibility, and complexity. This research investigated the use of tubular ceramic nanofiltration membranes to generate NBs in water with air, nitrogen and oxygen gases. This system injects <span class="hlt">pressurized</span> gases through a tubular ceramic membrane with nanopores to create NBs. The effects of membrane <span class="hlt">pores</span> size, surface energy, and the injected gas <span class="hlt">pressures</span> on the bubble size and zeta potential were examined. The results show that the gas injection <span class="hlt">pressure</span> had considerable effects on the bubble size, zeta potential, pH, and dissolved oxygen of the produced NBs. For example, increasing the injection air <span class="hlt">pressure</span> from 69 kPa to 414 kPa, the air bubble size was reduced from 600 to 340 nm respectively. Membrane <span class="hlt">pores</span> size and surface energy also had significant effects on sizes and zeta potentials of NBs. The results presented here aim to fill out the gaps of fundamental knowledge about NBs and development of efficient generation methods. Copyright © 2018 Elsevier Ltd. All rights reserved.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/29239426','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/29239426"><span>Heat of adsorption, adsorption stress, and optimal storage of methane in slit and cylindrical carbon <span class="hlt">pores</span> predicted by classical density functional theory.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Hlushak, Stepan</p> <p>2018-01-03</p> <p>Temperature, <span class="hlt">pressure</span> and <span class="hlt">pore</span>-size dependences of the heat of adsorption, adsorption stress, and adsorption capacity of methane in simple models of slit and cylindrical carbon <span class="hlt">pores</span> are studied using classical density functional theory (CDFT) and grand-canonical Monte-Carlo (MC) simulation. Studied properties depend nontrivially on the bulk <span class="hlt">pressure</span> and the size of the <span class="hlt">pores</span>. Heat of adsorption increases with loading, but only for sufficiently narrow <span class="hlt">pores</span>. While the increase is advantageous for gas storage applications, it is less significant for cylindrical <span class="hlt">pores</span> than for slits. Adsorption stress and the average adsorbed fluid density show oscillatory dependence on the <span class="hlt">pore</span> size and increase with bulk <span class="hlt">pressure</span>. Slit <span class="hlt">pores</span> exhibit larger amplitude of oscillations of the normal adsorption stress with <span class="hlt">pore</span> size increase than cylindrical <span class="hlt">pores</span>. However, the increase of the magnitude of the adsorption stress with bulk <span class="hlt">pressure</span> increase is more significant for cylindrical than for slit <span class="hlt">pores</span>. Adsorption stress appears to be negative for a wide range of <span class="hlt">pore</span> sizes and external conditions. The <span class="hlt">pore</span> size dependence of the average delivered density of the gas is analyzed and the optimal <span class="hlt">pore</span> sizes for storage applications are estimated. The optimal width of slit <span class="hlt">pore</span> appears to be almost independent of storage <span class="hlt">pressure</span> at room temperature and <span class="hlt">pressures</span> above 10 bar. Similarly to the case of slit <span class="hlt">pores</span>, the optimal radius of cylindrical <span class="hlt">pores</span> does not exhibit much dependence on the storage <span class="hlt">pressure</span> above 15 bar. Both optimal width and optimal radii of slit and cylindrical <span class="hlt">pores</span> increase as the temperature decreases. A comparison of the results of CDFT theory and MC simulations reveals subtle but important differences in the underlying fluid models employed by the approaches. The differences in the high-<span class="hlt">pressure</span> behaviour between the hard-sphere 2-Yukawa and Lennard-Jones models of methane, employed by the CDFT and MC approaches, respectively, result in an overestimation of</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017JOM....69i1600C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017JOM....69i1600C"><span>Dependence of CO2 Reactivity of Carbon Anodes on <span class="hlt">Pore</span> Structure</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Chen, Tong; Xue, Jilai; Lang, Guanghui; Liu, Rui; Gao, Shoulei; Wang, Zengjie</p> <p>2017-09-01</p> <p>The correlation between the CO2 reactivity and <span class="hlt">pore</span> structure of carbon anodes was experimentally investigated. The <span class="hlt">pore</span> structures of the anodes before and after CO2 oxidation were characterized using image analysis. The porosity, mean <span class="hlt">pore</span> diameter, and the number of micro-cracks decreased with increasing anode forming <span class="hlt">pressure</span>, while they increased with over-compaction. With prolonged CO2 oxidation time, the porosity, <span class="hlt">pore</span> density, mean <span class="hlt">pore</span> diameter, <span class="hlt">pore</span> aspect ratio, and the number of micro-cracks increased due to the merging of small <span class="hlt">pores</span>, increased <span class="hlt">pore</span> connectivity, and generation of new <span class="hlt">pores</span>. The activation energy decreased with increasing porosity of the anodes' pitch phase due to easier CO2 penetration and reaction within the anodes. The results confirm that the fine pitch-coke phase of anodes is preferentially consumed, a cause of carbon dusting. Optimization of the <span class="hlt">pore</span> structures to balance the pitch, coke, and butt phases may potentially further reduce carbon dusting.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=1262250','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=1262250"><span>The exocytotic fusion <span class="hlt">pore</span> modeled as a lipidic <span class="hlt">pore</span>.</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Nanavati, C; Markin, V S; Oberhauser, A F; Fernandez, J M</p> <p>1992-01-01</p> <p>Freeze-fracture electron micrographs from degranulating cells show that the lumen of the secretory granule is connected to the extracellular compartment via large (20 to 150 nm diameter) aqueous <span class="hlt">pores</span>. These exocytotic fusion <span class="hlt">pores</span> appear to be made up of a highly curved bilayer that spans the plasma and granule membranes. Conductance measurements, using the patch-clamp technique, have been used to study the fusion <span class="hlt">pore</span> from the instant it conducts ions. These measurements reveal the presence of early fusion <span class="hlt">pores</span> that are much smaller than those observed in electron micrographs. Early fusion <span class="hlt">pores</span> open abruptly, fluctuate, and then either expand irreversibly or close. The molecular structure of these early fusion <span class="hlt">pores</span> is unknown. In the simplest extremes, these early fusion <span class="hlt">pores</span> could be either ion channel like protein <span class="hlt">pores</span> or lipidic <span class="hlt">pores</span>. Here, we explored the latter possibility, namely that of the early exocytotic fusion <span class="hlt">pore</span> modeled as a lipid-lined <span class="hlt">pore</span> whose free energy was composed of curvature elastic energy and work done by tension. Like early exocytotic fusion <span class="hlt">pores</span>, we found that these lipidic <span class="hlt">pores</span> could open abruptly, fluctuate, and expand irreversibly. Closure of these lipidic <span class="hlt">pores</span> could be caused by slight changes in lipid composition. Conductance distributions for stable lipidic <span class="hlt">pores</span> matched those of exocytotic fusion <span class="hlt">pores</span>. These findings demonstrate that lipidic <span class="hlt">pores</span> can exhibit the properties of exocytotic fusion <span class="hlt">pores</span>, thus providing an alternate framework with which to understand and interpret exocytotic fusion <span class="hlt">pore</span> data. PMID:1420930</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014JAG...110...23L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014JAG...110...23L"><span>Carbonate <span class="hlt">pore</span> system evaluation using the velocity-porosity-<span class="hlt">pressure</span> relationship, digital image analysis, and differential effective medium theory</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Lima Neto, Irineu A.; Misságia, Roseane M.; Ceia, Marco A.; Archilha, Nathaly L.; Oliveira, Lucas C.</p> <p>2014-11-01</p> <p>Carbonate reservoirs exhibit heterogeneous <span class="hlt">pore</span> systems and a wide variety of grain types, which affect the rock's elastic properties and the reservoir parameter relationships. To study the Albian carbonates in the Campos Basin, a methodology is proposed to predict the amount of microporosity and the representative aspect ratio of these inclusions. The method assumes three <span class="hlt">pore</span>-space scales in two representative inclusion scenarios: 1) a macro-mesopore median aspect ratio from the thin-section digital image analysis (DIA) and 2) a microporosity aspect ratio predicted based on the measured P-wave velocities. Through a laboratory analysis of 10 grainstone core samples of the Albian age, the P- and S-wave velocities (Vp and Vs) are evaluated at effective <span class="hlt">pressures</span> of 0-10 MPa. The analytical theories in the proposed methodology are functions of the aspect ratios from the differential effective medium (DEM) theory, the macro-mesopore system recognized from the DIA, the amount of microporosity determined by the difference between the porosities estimated from laboratorial helium-gas and the thin-section petrographic images, and the P-wave velocities under dry effective <span class="hlt">pressure</span> conditions. The DIA procedure is applied to estimate the local and global parameters, and the textural implications concerning ultrasonic velocities and image resolution. The macro-mesopore inclusions contribute to stiffer rocks and higher velocities, whereas the microporosity inclusions contribute to softer rocks and lower velocities. We observe a high potential for this methodology, which uses the microporosity aspect ratio inverted from Vp to predict Vs with a good agreement. The results acceptably characterize the Albian grainstones. The representative macro-mesopore aspect ratio is 0.5, and the inverted microporosity aspect ratio ranges from 0.01 to 0.07. The effective <span class="hlt">pressure</span> induced an effect of slight porosity reduction during the triaxial tests, mainly in the microporosity inclusions</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5332984','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5332984"><span>Comparison of differences in respiratory function and <span class="hlt">pressure</span> as a predominant <span class="hlt">abnormal</span> movement of children with cerebral palsy</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Kwon, Hae-Yeon</p> <p>2017-01-01</p> <p>[Purpose] The purpose of this study was to determine differences in respiratory function and <span class="hlt">pressure</span> among three groups of children with cerebral palsy as a predominant <span class="hlt">abnormal</span> movement which included spastic type, dyskinetic type, and ataxic type. [Subjects and Methods] Forty-three children with cerebral palsy of 5–13 years of age in I–III levels according to the Gross Motor Function Classification System, the study subjects were divided by stratified random sampling into three groups of spastic type, dyskinetic type, and ataxic type. For reliability of the measurement results, respiratory function and <span class="hlt">pressure</span> of the children with cerebral palsy were measured by the same inspector using Spirometer Pony FX (Cosmed Ltd., Italy) equipment, and the subject’s guardians (legal representative) was always made to observe. [Results] In the respiratory function, there were significant differences among three groups in all of forced vital capacity, forced expiratory volume at one second, and peak expiratory flow. For respiratory <span class="hlt">pressure</span>, the maximal inspiratory <span class="hlt">pressure</span> had significant differences among three groups, although the maximal expiratory <span class="hlt">pressure</span> had no significant difference. [Conclusion] Therefore, pediatric physical therapists could be provided with important clinical information in understanding the differences in respiratory function and <span class="hlt">pressure</span> for the children with cerebral palsy showing predominantly <span class="hlt">abnormal</span> movement as a diverse qualitative characteristics of the muscle tone and movement patterns, and in planning intervention programs for improvement of respiratory capacity. PMID:28265153</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/29133919','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/29133919"><span>Integrating SANS and fluid-invasion methods to characterize <span class="hlt">pore</span> structure of typical American shale oil reservoirs.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Zhao, Jianhua; Jin, Zhijun; Hu, Qinhong; Jin, Zhenkui; Barber, Troy J; Zhang, Yuxiang; Bleuel, Markus</p> <p>2017-11-13</p> <p>An integration of small-angle neutron scattering (SANS), low-<span class="hlt">pressure</span> N 2 physisorption (LPNP), and mercury injection capillary <span class="hlt">pressure</span> (MICP) methods was employed to study the <span class="hlt">pore</span> structure of four oil shale samples from leading Niobrara, Wolfcamp, Bakken, and Utica Formations in USA. Porosity values obtained from SANS are higher than those from two fluid-invasion methods, due to the ability of neutrons to probe <span class="hlt">pore</span> spaces inaccessible to N 2 and mercury. However, SANS and LPNP methods exhibit a similar <span class="hlt">pore</span>-size distribution, and both methods (in measuring total <span class="hlt">pore</span> volume) show different results of porosity and <span class="hlt">pore</span>-size distribution obtained from the MICP method (quantifying <span class="hlt">pore</span> throats). Multi-scale (five <span class="hlt">pore</span>-diameter intervals) inaccessible porosity to N 2 was determined using SANS and LPNP data. Overall, a large value of inaccessible porosity occurs at <span class="hlt">pore</span> diameters <10 nm, which we attribute to low connectivity of organic matter-hosted and clay-associated <span class="hlt">pores</span> in these shales. While each method probes a unique aspect of complex <span class="hlt">pore</span> structure of shale, the discrepancy between <span class="hlt">pore</span> structure results from different methods is explained with respect to their difference in measurable ranges of <span class="hlt">pore</span> diameter, <span class="hlt">pore</span> space, <span class="hlt">pore</span> type, sample size and associated <span class="hlt">pore</span> connectivity, as well as theoretical base and interpretation.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/servlets/purl/1429067','SCIGOV-STC'); return false;" href="https://www.osti.gov/servlets/purl/1429067"><span>Changes in <span class="hlt">pore</span> structure of coal caused by coal-to-gas bioconversion</span></a></p> <p><a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a></p> <p>Zhang, Rui; Liu, Shimin; Bahadur, Jitendra</p> <p></p> <p>Microbial enhanced coalbed methane (ME-CBM) recovery is critically examined as a viable technology for natural gas recovery from coalbed methane (CBM) reservoirs. Since the majority of gas-in-place (GIP) is stored as an adsorbed phase in fine <span class="hlt">pores</span> of coal matrix, the nano-<span class="hlt">pore</span> structure directly influences gas storage and transport properties. Only limited studies have quantified the alteration of the nano-<span class="hlt">pore</span> structure due to ME-CBM treatment. This study examines the evolution of the <span class="hlt">pore</span> structure using a combination of small angle X-ray scattering (SAXS), low-<span class="hlt">pressure</span> N 2 and CO 2 adsorption (LPGA) and high-<span class="hlt">pressure</span> methane adsorption methods. The results show thatmore » the surface fractal dimension decreases for the two bioconverted coals compared to the untreated coal. After bio-treatment, the mesopore surface area and <span class="hlt">pore</span> volume decrease with the average <span class="hlt">pore</span> diameter increases, while the micropore surface area increases with <span class="hlt">pore</span> volume decreases. Both inaccessible meso-/micropore size distributions decrease after bioconversion, while the accessible micropore size distribution increases, making a portion of closed micropore network accessible. In addition, the methane adsorption capacities increase after bio-treatment, which is confirmed by the increase of micropore surface area. A conceptual physical model of methanogenesis is proposed based on the evolution of the <span class="hlt">pore</span> structure.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/pages/biblio/1429067-changes-pore-structure-coal-caused-coal-gas-bioconversion','SCIGOV-DOEP'); return false;" href="https://www.osti.gov/pages/biblio/1429067-changes-pore-structure-coal-caused-coal-gas-bioconversion"><span>Changes in <span class="hlt">pore</span> structure of coal caused by coal-to-gas bioconversion</span></a></p> <p><a target="_blank" href="http://www.osti.gov/pages">DOE PAGES</a></p> <p>Zhang, Rui; Liu, Shimin; Bahadur, Jitendra; ...</p> <p>2017-06-19</p> <p>Microbial enhanced coalbed methane (ME-CBM) recovery is critically examined as a viable technology for natural gas recovery from coalbed methane (CBM) reservoirs. Since the majority of gas-in-place (GIP) is stored as an adsorbed phase in fine <span class="hlt">pores</span> of coal matrix, the nano-<span class="hlt">pore</span> structure directly influences gas storage and transport properties. Only limited studies have quantified the alteration of the nano-<span class="hlt">pore</span> structure due to ME-CBM treatment. This study examines the evolution of the <span class="hlt">pore</span> structure using a combination of small angle X-ray scattering (SAXS), low-<span class="hlt">pressure</span> N 2 and CO 2 adsorption (LPGA) and high-<span class="hlt">pressure</span> methane adsorption methods. The results show thatmore » the surface fractal dimension decreases for the two bioconverted coals compared to the untreated coal. After bio-treatment, the mesopore surface area and <span class="hlt">pore</span> volume decrease with the average <span class="hlt">pore</span> diameter increases, while the micropore surface area increases with <span class="hlt">pore</span> volume decreases. Both inaccessible meso-/micropore size distributions decrease after bioconversion, while the accessible micropore size distribution increases, making a portion of closed micropore network accessible. In addition, the methane adsorption capacities increase after bio-treatment, which is confirmed by the increase of micropore surface area. A conceptual physical model of methanogenesis is proposed based on the evolution of the <span class="hlt">pore</span> structure.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017AGUFM.H21G1566E','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017AGUFM.H21G1566E"><span>Direct Numerical Simulation of Low Capillary Number <span class="hlt">Pore</span> Scale Flows</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Esmaeilzadeh, S.; Soulaine, C.; Tchelepi, H.</p> <p>2017-12-01</p> <p>The arrangement of void spaces and the granular structure of a porous medium determines multiple macroscopic properties of the rock such as porosity, capillary <span class="hlt">pressure</span>, and relative permeability. Therefore, it is important to study the microscopic structure of the reservoir <span class="hlt">pores</span> and understand the dynamics of fluid displacements through them. One approach for doing this, is direct numerical simulation of <span class="hlt">pore</span>-scale flow that requires a robust numerical tool for prediction of fluid dynamics and a detailed understanding of the physical processes occurring at the <span class="hlt">pore</span>-scale. In <span class="hlt">pore</span> scale flows with a low capillary number, Eulerian multiphase methods are well-known to produce additional vorticity close to the interface. This is mainly due to discretization errors which lead to an imbalance of capillary <span class="hlt">pressure</span> and surface tension forces that causes unphysical spurious currents. At the <span class="hlt">pore</span> scale, these spurious currents can become significantly stronger than the average velocity in the phases, and lead to unphysical displacement of the interface. In this work, we first investigate the capability of the algebraic Volume of Fluid (VOF) method in OpenFOAM for low capillary number <span class="hlt">pore</span> scale flow simulations. Afterward, we compare VOF results with a Coupled Level-Set Volume of Fluid (CLSVOF) method and Iso-Advector method. It has been shown that the former one reduces the VOF's unphysical spurious currents in some cases, and both are known to capture interfaces sharper than VOF. As the conclusion, we will investigate that whether the use of CLSVOF or Iso-Advector will lead to less spurious velocities and more accurate results for capillary driven <span class="hlt">pore</span>-scale multiphase flows or not. Keywords: <span class="hlt">Pore</span>-scale multiphase flow, Capillary driven flows, Spurious currents, OpenFOAM</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/20433539','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/20433539"><span>Relationship of hypertension, blood <span class="hlt">pressure</span>, and blood <span class="hlt">pressure</span> control with white matter <span class="hlt">abnormalities</span> in the Women's Health Initiative Memory Study (WHIMS)-MRI trial.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Kuller, Lewis H; Margolis, Karen L; Gaussoin, Sarah A; Bryan, Nick R; Kerwin, Diana; Limacher, Marian; Wassertheil-Smoller, Sylvia; Williamson, Jeff; Robinson, Jennifer G</p> <p>2010-03-01</p> <p>This paper evaluates the relationship of blood <span class="hlt">pressure</span> (BP) levels at Women's Health Initiative (WHI) baseline, treatment of hypertension, and white matter <span class="hlt">abnormalities</span> among women in conjugated equine estrogen (CEE) and medroxyprogesterone acetate and CEE-alone arms. The WHI Memory Study-Magnetic Resonance Imaging (WHIMS-MRI) trial scanned 1424 participants. BP levels at baseline were significantly positively related to <span class="hlt">abnormal</span> white matter lesion (WML) volumes. Participants treated for hypertension but who had BP > or = 140/90 mm Hg had the greatest amount of WML volumes. Women with untreated BP > or = 140/90 mm Hg had intermediate WML volumes. <span class="hlt">Abnormal</span> WML volumes were related to hypertension in most areas of the brain and were greater in the frontal lobe than in the occipital, parietal, or temporal lobes. Level of BP at baseline was strongly related to amount of WML volumes. The results of the study reinforce the relationship of hypertension and BP control and white matter <span class="hlt">abnormalities</span> in the brain. The evidence to date supports tight control of BP levels, especially beginning at younger and middle age as a possible and perhaps only way to prevent dementia.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_7");'>7</a></li> <li><a href="#" onclick='return showDiv("page_8");'>8</a></li> <li class="active"><span>9</span></li> <li><a href="#" onclick='return showDiv("page_10");'>10</a></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_9 --> <div id="page_10" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_8");'>8</a></li> <li><a href="#" onclick='return showDiv("page_9");'>9</a></li> <li class="active"><span>10</span></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="181"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2006AGUFM.V43A1771M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2006AGUFM.V43A1771M"><span>The influence of <span class="hlt">pore</span> textures on the permeability of volcanic rocks</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Mueller, S.; Spieler, O.; Scheu, B.; Dingwell, D.</p> <p>2006-12-01</p> <p>The permeability of a porous medium is strongly dependent on its porosity, as a higher proportion of <span class="hlt">pore</span> volume is generally expected to lead to a greater probability of <span class="hlt">pore</span> interconnectedness and the formation of a fluid-flow providing pathway. However, the relationship between permeability and porosity is not a unique one, as many other textural parameters may play an important role and substantially affect gas flow properties. Among these parameters are (a) the connection geometry (i.e. intergranular <span class="hlt">pore</span> spaces in clastic sediments vs. bubble interconnections), (b) the <span class="hlt">pore</span> sizes, (c) <span class="hlt">pore</span> shape and (d) <span class="hlt">pore</span> size distribution. The gas permeability of volcanic rocks may influence various eruptive processes. The transition from a quiescent degassing dome to rock failure (fragmentation) may, for example, be controlled by the rock's permeability, in as much as it affects the speed by which a gas overpressure in vesicles is reduced in response to decompression. It is therefore essential to understand and quantify influences of different <span class="hlt">pore</span> textures on the degassing properties of volcanic rocks, as well as investigate the effects of permeability on eruptive processes. Using a modified shock-tube-based fragmentation apparatus, we have measured unsteady-state permeability at a high initial <span class="hlt">pressure</span> differential. Following sudden decompression above the rock cylinder, <span class="hlt">pressurized</span> gas flows through the sample in a steel autoclave. A transient 1D filtration code has been developed to calculate permeability using the experimental <span class="hlt">pressure</span> decay curve within a defined volume below the sample. An external furnace around the autoclave and the use of compressed salt as sealant allows also measurements at high temperatures up to 800 °C. Over 130 permeability measurements have been performed on samples of different volcanic settings, covering a wide range of porosity. The results show a general positive relationship between porosity and permeability with a high data scatter</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/23937617','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/23937617"><span>Application of a drainage film reduces fibroblast ingrowth into large-<span class="hlt">pored</span> polyurethane foam during negative-<span class="hlt">pressure</span> wound therapy in an in vitro model.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Wiegand, Cornelia; Springer, Steffen; Abel, Martin; Wesarg, Falko; Ruth, Peter; Hipler, Uta-Christina</p> <p>2013-01-01</p> <p>Negative-<span class="hlt">pressure</span> wound therapy (NPWT) is an advantageous treatment option in wound management to promote healing and reduce the risk of complications. NPWT is mainly carried out using open-cell polyurethane (PU) foams that stimulate granulation tissue formation. However, growth of wound bed tissue into foam material, leading to disruption of newly formed tissue upon dressing removal, has been observed. Consequently, it would be of clinical interest to preserve the positive effects of open-cell PU foams while avoiding cellular ingrowth. The study presented analyzed effects of NPWT using large-<span class="hlt">pored</span> PU foam, fine-<span class="hlt">pored</span> PU foam, and the combination of large-<span class="hlt">pored</span> foam with drainage film on human dermal fibroblasts grown in a collagen matrix. The results showed no difference between the dressings in stimulating cellular migration during NPWT. However, when NPWT was applied using a large-<span class="hlt">pored</span> PU foam, the fibroblasts continued to migrate into the dressing. This led to significant breaches in the cell layers upon removal of the samples after vacuum treatment. In contrast, cell migration stopped at the collagen matrix edge when fine-<span class="hlt">pored</span> PU foam was used, as well as with the combination of PU foam and drainage film. In conclusion, placing a drainage film between collagen matrix and the large-<span class="hlt">pored</span> PU foam dressing reduced the ingrowth of cells into the foam significantly. Moreover, positive effects on cellular migration were not affected, and the effect of the foam on tissue surface roughness in vitro was also reduced. © 2013 by the Wound Healing Society.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4601026','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4601026"><span><span class="hlt">Pressure</span>-Induced Amorphization of Small <span class="hlt">Pore</span> Zeolites—the Role of Cation-H2O Topology and Anti-glass Formation</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Chan Hwang, Gil; Joo Shin, Tae; Blom, Douglas A.; Vogt, Thomas; Lee, Yongjae</p> <p>2015-01-01</p> <p>Systematic studies of <span class="hlt">pressure</span>-induced amorphization of natrolites (PIA) containing monovalent extra-framework cations (EFC) Li+, Na+, K+, Rb+, Cs+ allow us to assess the role of two different EFC-H2O configurations within the <span class="hlt">pores</span> of a zeolite: one arrangement has H2O molecules (NATI) and the other the EFC (NATII) in closer proximity to the aluminosilicate framework. We show that NATI materials have a lower onset <span class="hlt">pressure</span> of PIA than the NATII materials containing Rb and Cs as EFC. The onset <span class="hlt">pressure</span> of amorphization (PA) of NATII materials increases linearly with the size of the EFC, whereas their initial bulk moduli (P1 phase) decrease linearly. Only Cs- and Rb-NAT reveal a phase separation into a dense form (P2 phase) under <span class="hlt">pressure</span>. High-Angle Annular Dark Field Scanning Transmission Electron Microscopy (HAADF-STEM) imaging shows that after recovery from <span class="hlt">pressures</span> near 25 and 20 GPa long-range ordered Rb-Rb and Cs-Cs correlations continue to be present over length scales up to 100 nm while short-range ordering of the aluminosilicate framework is significantly reduced—this opens a new way to form anti-glass structures. PMID:26455345</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/26455345','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26455345"><span><span class="hlt">Pressure</span>-Induced Amorphization of Small <span class="hlt">Pore</span> Zeolites-the Role of Cation-H2O Topology and Anti-glass Formation.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Chan Hwang, Gil; Joo Shin, Tae; Blom, Douglas A; Vogt, Thomas; Lee, Yongjae</p> <p>2015-10-12</p> <p>Systematic studies of <span class="hlt">pressure</span>-induced amorphization of natrolites (PIA) containing monovalent extra-framework cations (EFC) Li(+), Na(+), K(+), Rb(+), Cs(+) allow us to assess the role of two different EFC-H2O configurations within the <span class="hlt">pores</span> of a zeolite: one arrangement has H2O molecules (NATI) and the other the EFC (NATII) in closer proximity to the aluminosilicate framework. We show that NATI materials have a lower onset <span class="hlt">pressure</span> of PIA than the NATII materials containing Rb and Cs as EFC. The onset <span class="hlt">pressure</span> of amorphization (PA) of NATII materials increases linearly with the size of the EFC, whereas their initial bulk moduli (P1 phase) decrease linearly. Only Cs- and Rb-NAT reveal a phase separation into a dense form (P2 phase) under <span class="hlt">pressure</span>. High-Angle Annular Dark Field Scanning Transmission Electron Microscopy (HAADF-STEM) imaging shows that after recovery from <span class="hlt">pressures</span> near 25 and 20 GPa long-range ordered Rb-Rb and Cs-Cs correlations continue to be present over length scales up to 100 nm while short-range ordering of the aluminosilicate framework is significantly reduced-this opens a new way to form anti-glass structures.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.dtic.mil/docs/citations/ADA124668','DTIC-ST'); return false;" href="http://www.dtic.mil/docs/citations/ADA124668"><span>Ultrasonic Inspection and Fatigue Evaluation of Critical <span class="hlt">Pore</span> Size in Welds.</span></a></p> <p><a target="_blank" href="http://www.dtic.mil/">DTIC Science & Technology</a></p> <p></p> <p>1981-09-01</p> <p>Boiler and <span class="hlt">Pressure</span> Vessel Code ) 20...Five porosity levels were produced that parallelled ASME boiler and <span class="hlt">pressure</span> vessel code specification (Section VIII). Appendix IV of the <span class="hlt">pressure</span>...Figure 2 shows porosity charts (ASME Boiler and <span class="hlt">Pressure</span> Vessel Code ) which classify and designate the number and size of <span class="hlt">pores</span> in any six inch length</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/biblio/1083732-particle-deformation-concentration-polarization-electroosmotic-transport-hydrogels-through-pores','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/1083732-particle-deformation-concentration-polarization-electroosmotic-transport-hydrogels-through-pores"><span>Particle Deformation and Concentration Polarization in Electroosmotic Transport of Hydrogels through <span class="hlt">Pores</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a></p> <p>Vlassiouk, Ivan V</p> <p>2013-01-01</p> <p>In this article, we report detection of deformable, hydrogel particles by the resistive-pulse technique using single <span class="hlt">pores</span> in a polymer film. The hydrogels pass through the <span class="hlt">pores</span> by electroosmosis and cause formation of a characteristic shape of resistive pulses indicating the particles underwent dehydration and deformation. These effects were explained via a non-homogeneous <span class="hlt">pressure</span> distribution along the <span class="hlt">pore</span> axis modeled by the coupled Poisson-Nernst-Planck and Navier Stokes equations. The local <span class="hlt">pressure</span> drops are induced by the electroosmotic fluid flow. Our experiments also revealed the importance of concentration polarization in the detection of hydrogels. Due to the negative charges as wellmore » as branched, low density structure of the hydrogel particles, concentration of ions in the particles is significantly higher than in the bulk. As a result, when electric field is applied across the membrane, a depletion zone can be created in the vicinity of the particle observed as a transient drop of the current. Our experiments using <span class="hlt">pores</span> with openings between 200 and 1600 nm indicated the concentration polarization dominated the hydrogels detection for <span class="hlt">pores</span> wider than 450 nm. The results are of importance for all studies that involve transport of molecules, particles and cells through <span class="hlt">pores</span> with charged walls. The developed inhomogeneous <span class="hlt">pressure</span> distribution can potentially influence the shape of the transported species. The concentration polarization changes the interpretation of the resistive pulses; the observed current change does not necessarily reflect only the particle size but also the size of the depletion zone that is formed in the particle vicinity.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2005ApSS..248..446V','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2005ApSS..248..446V"><span>Modelling the influence of <span class="hlt">pore</span> size on the response of materials to infrared lasers An application to human enamel</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Vila Verde, A.; Ramos, Marta M. D.</p> <p>2005-07-01</p> <p>We present an analytical model for a ceramic material (hydroxyapatite, HA) containing nanometre-scale water <span class="hlt">pores</span>, and use it to estimate the <span class="hlt">pressure</span> at the <span class="hlt">pore</span> as a function of temperature at the end of a single 0.35 μs laser pulse by Er:YAG (2.94 μm) and CO 2 (10.6 μm) lasers. Our results suggest that the <span class="hlt">pressure</span> at the <span class="hlt">pore</span> is directly related to <span class="hlt">pore</span> temperature, and that very high <span class="hlt">pressures</span> can be generated simply by the thermal expansion of liquid water. Since the temperature reached in the <span class="hlt">pores</span> at the end of the laser pulse is a strong function of <span class="hlt">pore</span> size for Er:YAG lasers, but is independent of <span class="hlt">pore</span> size for CO 2 lasers, our present results provide a possible explanation for the fact that human dental enamel threshold ablation fluences vary more for Er:YAG lasers than for CO 2 lasers. This suggests that experimentalists should analyse their results accounting for factors, like age or type of tooth, that may change the <span class="hlt">pore</span> size distribution in their samples.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013PhDT.......528M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013PhDT.......528M"><span>Best Practices for Mudweight Window Generation and Accuracy Assessment between Seismic Based <span class="hlt">Pore</span> <span class="hlt">Pressure</span> Prediction Methodologies for a Near-Salt Field in Mississippi Canyon, Gulf of Mexico</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Mannon, Timothy Patrick, Jr.</p> <p></p> <p>Improving well design has and always will be the primary goal in drilling operations in the oil and gas industry. Oil and gas plays are continuing to move into increasingly hostile drilling environments, including near and/or sub-salt proximities. The ability to reduce the risk and uncertainly involved in drilling operations in unconventional geologic settings starts with improving the techniques for mudweight window modeling. To address this issue, an analysis of wellbore stability and well design improvement has been conducted. This study will show a systematic approach to well design by focusing on best practices for mudweight window projection for a field in Mississippi Canyon, Gulf of Mexico. The field includes depleted reservoirs and is in close proximity of salt intrusions. Analysis of offset wells has been conducted in the interest of developing an accurate picture of the subsurface environment by making connections between depth, non-productive time (NPT) events, and mudweights used. Commonly practiced petrophysical methods of <span class="hlt">pore</span> <span class="hlt">pressure</span>, fracture <span class="hlt">pressure</span>, and shear failure gradient prediction have been applied to key offset wells in order to enhance the well design for two proposed wells. For the first time in the literature, the accuracy of the commonly accepted, seismic interval velocity based and the relatively new, seismic frequency based methodologies for <span class="hlt">pore</span> <span class="hlt">pressure</span> prediction are qualitatively and quantitatively compared for accuracy. Accuracy standards will be based on the agreement of the seismic outputs to <span class="hlt">pressure</span> data obtained while drilling and petrophysically based <span class="hlt">pore</span> <span class="hlt">pressure</span> outputs for each well. The results will show significantly higher accuracy for the seismic frequency based approach in wells that were in near/sub-salt environments and higher overall accuracy for all of the wells in the study as a whole.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/17042533','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/17042533"><span>Change in desorption mechanism from <span class="hlt">pore</span> blocking to cavitation with temperature for nitrogen in ordered silica with cagelike <span class="hlt">pores</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Morishige, Kunimitsu; Tateishi, Masayoshi; Hirose, Fumi; Aramaki, Kenji</p> <p>2006-10-24</p> <p>To verify <span class="hlt">pore</span> blocking controlled desorption in ink-bottle <span class="hlt">pores</span>, we measured the temperature dependence of the adsorption-desorption isotherms of nitrogen on four kinds of KIT-5 samples with expanded cavities hydrothermally treated for different periods of time at 393 K. In the samples, almost spherical cavities are arranged in a face-centered cubic array and the cavities are connected through small channels. The <span class="hlt">pore</span> size of the channels increased with an increase in the hydrothermal treatment time. At lower temperatures a steep desorption branch changed to a gradual one as the hydrothermal treatment was prolonged. For the sample hydrothermally treated only for 1 day, the rectangular hysteresis loop shrank gradually with increasing temperature while keeping its shape. The temperature dependence of the evaporation <span class="hlt">pressure</span> observed was identical with that expected for cavitation-controlled desorption. On the other hand, for the samples hydrothermally treated for long times, the gradual desorption branch became a sharp one with increasing temperature. This strongly suggests that the desorption mechanism is altered from <span class="hlt">pore</span> blocking to cavitation with temperature. Application of percolation theory to the <span class="hlt">pore</span> blocking controlled desorption observed here is discussed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013AGUFM.T31F2572K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013AGUFM.T31F2572K"><span>Response to long-period seismic waves recorded by broadband seismometer and <span class="hlt">pore</span> <span class="hlt">pressure</span> sensor at IODP Site C0002, Nankai Trough</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kitada, K.; Araki, E.; Kimura, T.; Saffer, D. M.</p> <p>2013-12-01</p> <p>Long term in situ monitoring of seismic activity, slow slip event, and <span class="hlt">pore</span> fluid behavior around mega earthquake zone is important for understanding the processes of earthquake generation and strain accumulation. In order to characterize the response to long-period seismic waves, we compared waveforms and hydroseismograms recorded by broadband seismometer and <span class="hlt">pore</span> <span class="hlt">pressure</span> transducers, respectively, which were installed at IODP Site C0002 in the Nankai Trough Kumano Basin. The borehole monitoring system sensor array at Site C0002 is designed to collect multiparameter observations covering a dynamic range of events, including local microearthquakes, low frequency earthquakes, and large-scale earthquakes similar to the Tonankai earthquake. The suite of sensors for the downhole portion of the observatory includes a broadband seismometer (CMG3TBD, Guralp Systems Ltd.) with sampling rate of 100Hz at the depth of 907mbsf, and four <span class="hlt">pressure</span> ports connected to <span class="hlt">pressure</span> gauges located at 948mbsf, 917mbsf, 766mbsf, and at the seafloor. The sampling rate of the data logger was set to 1Hz after successful connection to the DONET seafloor cable network for real-time monitoring on 24 Jan 2013. Since then, we processed 12 earthquakes between a moment magnitude of 6.5 to 8.3. In addition to the comparison of long-period surface waves waveform and <span class="hlt">pressure</span> data, we compared the records with theoretical strain seismograms. The latter were calculated by normal mode summation using the earth model PREM of Dziewonski and Anderson (1981). A Butterworth bandpass filter was applied to the records with cut-off frequencies of 0.003 and 0.1 Hz. Our initial results indicate that the hydroseismograms correspond well with the vertical rather than the horizontal (radial and transverse) components in seismic data. The observed hydroseismogram have a good correlation with the predicted volumetric strain seismogram, especially for the Okhotsk (2013/05/24 14:17UT, Mw8.3, 632km depth), the Chishima</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/29547396','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/29547396"><span>Understanding the role of <span class="hlt">pore</span> size homogeneity in the water transport through graphene layers.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Su, Jiaye; Zhao, Yunzhen; Fang, Chang</p> <p>2018-06-01</p> <p>Graphene is a versatile 2D material and attracts an increasing amount of attention from a broad scientific community, including novel nanofluidic devices. In this work, we use molecular dynamics simulations to study the <span class="hlt">pressure</span> driven water transport through graphene layers, focusing on the <span class="hlt">pore</span> size homogeneity, realized by the arrangement of two <span class="hlt">pore</span> sizes. For a given layer number, we find that water flux exhibits an excellent linear behavior with <span class="hlt">pressure</span>, in agreement with the prediction of the Hagen-Poiseuille equation. Interestingly, the flux for concentrated <span class="hlt">pore</span> size distribution is around two times larger than that of a uniform distribution. More surprisingly, under a given <span class="hlt">pressure</span>, the water flux changes in an opposite way for these two distributions, where the flux ratio almost increases linearly with the layer number. For the largest layer number, more distributions suggest the same conclusion that higher water flux can be attained for more concentrated <span class="hlt">pore</span> size distributions. Similar differences for the water translocation time and occupancy are also identified. The major reason for these results should clearly be due to the hydrogen bond and density profile distributions. Our results are helpful to delineate the exquisite role of <span class="hlt">pore</span> size homogeneity, and should have great implications for the design of high flux nanofluidic devices and inversely the detection of <span class="hlt">pore</span> structures.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018Nanot..29v5706S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018Nanot..29v5706S"><span>Understanding the role of <span class="hlt">pore</span> size homogeneity in the water transport through graphene layers</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Su, Jiaye; Zhao, Yunzhen; Fang, Chang</p> <p>2018-06-01</p> <p>Graphene is a versatile 2D material and attracts an increasing amount of attention from a broad scientific community, including novel nanofluidic devices. In this work, we use molecular dynamics simulations to study the <span class="hlt">pressure</span> driven water transport through graphene layers, focusing on the <span class="hlt">pore</span> size homogeneity, realized by the arrangement of two <span class="hlt">pore</span> sizes. For a given layer number, we find that water flux exhibits an excellent linear behavior with <span class="hlt">pressure</span>, in agreement with the prediction of the Hagen–Poiseuille equation. Interestingly, the flux for concentrated <span class="hlt">pore</span> size distribution is around two times larger than that of a uniform distribution. More surprisingly, under a given <span class="hlt">pressure</span>, the water flux changes in an opposite way for these two distributions, where the flux ratio almost increases linearly with the layer number. For the largest layer number, more distributions suggest the same conclusion that higher water flux can be attained for more concentrated <span class="hlt">pore</span> size distributions. Similar differences for the water translocation time and occupancy are also identified. The major reason for these results should clearly be due to the hydrogen bond and density profile distributions. Our results are helpful to delineate the exquisite role of <span class="hlt">pore</span> size homogeneity, and should have great implications for the design of high flux nanofluidic devices and inversely the detection of <span class="hlt">pore</span> structures.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5126630','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5126630"><span>Research of CO2 and N2 Adsorption Behavior in K-Illite Slit <span class="hlt">Pores</span> by GCMC Method</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Chen, Guohui; Lu, Shuangfang; Zhang, Junfang; Xue, Qingzhong; Han, Tongcheng; Xue, Haitao; Tian, Shansi; Li, Jinbu; Xu, Chenxi; Pervukhina, Marina; Clennell, Ben</p> <p>2016-01-01</p> <p>Understanding the adsorption mechanisms of CO2 and N2 in illite, one of the main components of clay in shale, is important to improve the precision of the shale gas exploration and development. We investigated the adsorption mechanisms of CO2 and N2 in K-illite with varying <span class="hlt">pore</span> sizes at the temperature of 333, 363 and 393 K over a broad range of <span class="hlt">pressures</span> up to 30 MPa using the grand canonical Monte Carlo (GCMC) simulation method. The simulation system is proved to be reasonable and suitable through the discussion of the impact of cation dynamics and <span class="hlt">pore</span> wall thickness. The simulation results of the excess adsorption amount, expressed per unit surface area of illite, is in general consistency with published experimental results. It is found that the sorption potential overlaps in micropores, leading to a decreasing excess adsorption amount with the increase of <span class="hlt">pore</span> size at low <span class="hlt">pressure</span>, and a reverse trend at high <span class="hlt">pressure</span>. The excess adsorption amount increases with increasing <span class="hlt">pressure</span> to a maximum and then decreases with further increase in the <span class="hlt">pressure</span>, and the decreasing amount is found to increase with the increasing <span class="hlt">pore</span> size. For <span class="hlt">pores</span> with size greater larger than 2 nm, the overlap effect disappears. PMID:27897232</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016AGUFM.H51B1469C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016AGUFM.H51B1469C"><span>Investigation of Coupled model of <span class="hlt">Pore</span> network and Continuum in shale gas</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Cao, G.; Lin, M.</p> <p>2016-12-01</p> <p>Flow in shale spanning over many scales, makes the majority of conventional treatment methods disabled. For effectively simulating, a coupled model of <span class="hlt">pore</span>-scale and continuum-scale was proposed in this paper. Based on the SEM image, we decompose organic-rich-shale into two subdomains: kerogen and inorganic matrix. In kerogen, the nanoscale <span class="hlt">pore</span>-network is the main storage space and migration pathway so that the molecular phenomena (slip and diffusive transport) is significant. Whereas, inorganic matrix, with relatively large <span class="hlt">pores</span> and micro fractures, the flow is approximate to Darcy. We use <span class="hlt">pore</span>-scale network models (PNM) to represent kerogen and continuum-scale models (FVM or FEM) to represent matrix. Finite element mortars are employed to couple <span class="hlt">pore</span>- and continuum-scale models by enforcing continuity of <span class="hlt">pressures</span> and fluxes at shared boundary interfaces. In our method, the process in the coupled model is described by <span class="hlt">pressure</span> square equation, and uses Dirichlet boundary conditions. We discuss several problems: the optimal element number of mortar faces, two categories boundary faces of <span class="hlt">pore</span> network, the difference between 2D and 3D models, and the difference between continuum models FVM and FEM in mortars. We conclude that: (1) too coarse mesh in mortars will decrease the accuracy, while too fine mesh will lead to an ill-condition even singular system, the optimal element number is depended on boundary <span class="hlt">pores</span> and nodes number. (2) <span class="hlt">pore</span> network models are adjacent to two different mortar faces (PNM to PNM, PNM to continuum model), incidental repeated mortar nodes must be deleted. (3) 3D models can be replaced by 2D models under certain condition. (4) FVM is more convenient than FEM, for its simplicity in assigning interface nodes <span class="hlt">pressure</span> and calculating interface fluxes. This work is supported by the Strategic Priority Research Program of the Chinese Academy of Sciences (XDB10020302), the 973 Program (2014CB239004), the Key Instrument Developing Project of the</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016APS..MARP37001V','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016APS..MARP37001V"><span>Nonlinear transport of soft droplets in <span class="hlt">pore</span> networks</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Vernerey, Franck; Benet Cerda, Eduard; Koo, Kanghyeon</p> <p></p> <p>A large number of biological and technological processes depend on the transport of soft colloidal particles through porous media; this includes the transport and separation of cells, viruses or drugs through tissues, membranes and microfluidic devices. In these systems, the interactions between soft particles, background fluid and the surrounding <span class="hlt">pore</span> space yield complex, nonlinear behaviors such as non-Darcy flows, localization and jamming. We devise a computational strategy to investigate the transport of non-wetting and deformable water droplets in a microfluidic device made of a random distribution of cylindrical obstacles. We first derive scaling laws for the entry of the droplet in a single <span class="hlt">pore</span> and discuss the role of surface tension, contact angle and size in this process. This information is then used to study the transport of multiple droplets in an obstacle network. We find that when the droplet size is close to the <span class="hlt">pore</span> size, fluid flow and droplet trafficking strongly interact, leading to local redistributions in <span class="hlt">pressure</span> fields, intermittent clogging and jamming. Importantly, it is found that the overall droplet and fluid transport display three different scaling regimes depending on the forcing <span class="hlt">pressure</span>, and that these regimes can be related to droplet properties.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2003AGUFM.H12K..04S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2003AGUFM.H12K..04S"><span>Soil-Moisture Retention Curves, Capillary <span class="hlt">Pressure</span> Curves, and Mercury Porosimetry: A Theoretical and Computational Investigation of the Determination of the Geometric Properties of the <span class="hlt">Pore</span> Space</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Strand, T. E.; Wang, H. F.</p> <p>2003-12-01</p> <p>Immiscible displacement protocols have long been used to infer the geometric properties of the void space in granular porous media. The three most commonly used experimental techniques are the measurement of soil-moisture retention curves and relative permeability-capillary <span class="hlt">pressure</span>-saturation relations, as well as mercury intrusion porosimetry experiments. A coupled theoretical and computational investigation was performed that provides insight into the limitations associated with each technique and quantifies the relationship between experimental observations and the geometric properties of the void space. It is demonstrated that the inference of the <span class="hlt">pore</span> space geometry from both mercury porosimetry experiments and measurements of capillary <span class="hlt">pressure</span> curves is influenced by trapping/mobilization phenomena and subject to scaling behavior. In addition, both techniques also assume that the capillary <span class="hlt">pressure</span> at a location on the meniscus can be approximated by a <span class="hlt">pressure</span> difference across a region or sample. For example, when performing capillary <span class="hlt">pressure</span> measurements, the capillary <span class="hlt">pressure</span>, taken to be the difference between the injected fluid <span class="hlt">pressure</span> at the inlet and the defending fluid <span class="hlt">pressure</span> at the outlet, is increased in a series of small steps and the fluid saturation is measured each time the system reaches steady. Regions of defending fluid that become entrapped by the invading fluid can be subsequently mobilized at higher flow rates (capillary <span class="hlt">pressures</span>), contributing to a scale-dependence of the capillary <span class="hlt">pressure</span>-saturation curve that complicates the determination of the properties of the <span class="hlt">pore</span> space. This scale-dependence is particularly problematic for measurements performed at the core scale. Mercury porosimetry experiments are subject to similar limitations. Trapped regions of defending fluid are also present during the measurement of soil-moisture retention curves, but the effects of scaling behavior on the evaluation of the <span class="hlt">pore</span> space properties</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017AdWR..110..120M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017AdWR..110..120M"><span>Toward direct <span class="hlt">pore</span>-scale modeling of three-phase displacements</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Mohammadmoradi, Peyman; Kantzas, Apostolos</p> <p>2017-12-01</p> <p>A stable spreading film between water and gas can extract a significant amount of bypassed non-aqueous phase liquid (NAPL) through immiscible three-phase gas/water injection cycles. In this study, the <span class="hlt">pore</span>-scale displacement mechanisms by which NAPL is mobilized are incorporated into a three-dimensional <span class="hlt">pore</span> morphology-based model under water-wet and capillary equilibrium conditions. The approach is pixel-based and the sequence of invasions is determined by the fluids' connectivity and the threshold capillary <span class="hlt">pressure</span> of the advancing interfaces. In addition to the determination of three-phase spatial saturation profiles, residuals, and capillary <span class="hlt">pressure</span> curves, dynamic finite element simulations are utilized to predict the effective permeabilities of the rock microtomographic images as reasonable representations of the geological formations under study. All the influential features during immiscible fluid flow in <span class="hlt">pore</span>-level domains including wetting and spreading films, saturation hysteresis, capillary trapping, connectivity, and interface development strategies are taken into account. The capabilities of the model are demonstrated by the successful prediction of saturation functions for Berea sandstone and the accurate reconstruction of three-phase fluid occupancies through a micromodel.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018PhRvE..97e2114M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018PhRvE..97e2114M"><span>Virial series expansion and Monte Carlo studies of equation of state for hard spheres in narrow cylindrical <span class="hlt">pores</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Mon, K. K.</p> <p>2018-05-01</p> <p>In this paper, the virial series expansion and constant <span class="hlt">pressure</span> Monte Carlo method are used to study the longitudinal <span class="hlt">pressure</span> equation of state for hard spheres in narrow cylindrical <span class="hlt">pores</span>. We invoke dimensional reduction and map the model into an effective one-dimensional fluid model with interacting internal degrees of freedom. The one-dimensional model is extensive. The Euler relation holds, and longitudinal <span class="hlt">pressure</span> can be probed with the standard virial series expansion method. Virial coefficients B2 and B3 were obtained analytically, and numerical quadrature was used for B4. A range of narrow <span class="hlt">pore</span> widths (2 Rp) , Rp<(√{3 }+2 ) /4 =0.9330 ... (in units of the hard sphere diameter) was used, corresponding to fluids in the important single-file formations. We have also computed the virial <span class="hlt">pressure</span> series coefficients B2', B3', and B4' to compare a truncated virial <span class="hlt">pressure</span> series equation of state with accurate constant <span class="hlt">pressure</span> Monte Carlo data. We find very good agreement for a wide range of <span class="hlt">pressures</span> for narrow <span class="hlt">pores</span>. These results contribute toward increasing the rather limited understanding of virial coefficients and the equation of state of hard sphere fluids in narrow cylindrical <span class="hlt">pores</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012AGUFM.S44B..07G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012AGUFM.S44B..07G"><span>Slow slip pulses driven by thermal <span class="hlt">pressurization</span> of <span class="hlt">pore</span> fluid: theory and observational constraints</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Garagash, D.</p> <p>2012-12-01</p> <p>We discuss recently developed solutions for steadily propagating self-healing slip pulses driven by thermal <span class="hlt">pressurization</span> (TP) of <span class="hlt">pore</span> fluid [Garagash, 2012] on a fault with a constant sliding friction. These pulses are characterized by initial stage of undrained weakening of the fault (when fluid/heat can not yet escape the frictionally heated shear zone), which gives way to partial restrengthening due to increasing hydrothermal diffusion under conditions of diminished rate of heating, leading to eventual locking of the slip. The rupture speed of these pulses is decreasing function of the thickness (h) of the principal shear zone. We find that "thick" shear zones, h >> hdyna, where hdyna = (μ/τ0) (ρc/fΛ)(4α/cs), can support aseismic TP pulses propagating at a fraction hdyna/h of the shear wave speed cs, while "thin" shear zones, h˜hdyna or thinner, can only harbor seismic slip. (Here μ - shear modulus, τ0 - the nominal fault strength, f - sliding friction, ρc - the heat capacity of the fault gouge, Λ - the fluid thermal <span class="hlt">pressurization</span> factor, α - hydrothermal diffusivity parameter of the gouge). For plausible range of fault parameters, hdyna is between 10s to 100s of micrometers, suggesting that slow slip transients propagating at 1 to 10 km/day may occur in the form of a TP slip pulse accommodated by a meter-thick shear zone. We verify that this is, indeed, a possibility by contrasting the predictions for aseismic, small-slip TP pulses operating at seismologically-constrained, near-lithostatic <span class="hlt">pore</span> <span class="hlt">pressure</span> (effective normal stress ≈ 3 to 10 MPa) with the observations (slip duration at a given fault location ≈ week, propagation speed ≈ 15 km/day, and the inferred total slip ≈ 2 to 3 cm) for along-strike propagation of the North Cascadia slow slip events of '98-99 [Dragert et al., 2001, 2004]. Furthermore, we show that the effect of thermal <span class="hlt">pressurization</span> on the strength of the subduction interface is comparable to or exceeds that of the rate</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017AGUFM.S51E..08B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017AGUFM.S51E..08B"><span>New Laboratory Observations of Thermal <span class="hlt">Pressurization</span> Weakening</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Badt, N.; Tullis, T. E.; Hirth, G.</p> <p>2017-12-01</p> <p>Dynamic frictional weakening due to <span class="hlt">pore</span> fluid thermal <span class="hlt">pressurization</span> has been studied under elevated confining <span class="hlt">pressure</span> in the laboratory, using a rotary-shear apparatus having a sample with independent <span class="hlt">pore</span> <span class="hlt">pressure</span> and confining <span class="hlt">pressure</span> systems. Thermal <span class="hlt">pressurization</span> is directly controlled by the permeability of the rocks, not only for the initiation of high-speed frictional weakening but also for a subsequent sequence of high-speed sliding events. First, the permeability is evaluated at different effective <span class="hlt">pressures</span> using a method where the <span class="hlt">pore</span> <span class="hlt">pressure</span> drop and the flow-through rate are compared using Darcy's Law as well as a <span class="hlt">pore</span> fluid oscillation method, the latter method also permitting measurement of the storage capacity. Then, the samples undergo a series of high-speed frictional sliding segments at a velocity of 2.5 mm/s, under an applied confining <span class="hlt">pressure</span> and normal stress of 45 MPa and 50 MPa, respectively, and an initial <span class="hlt">pore</span> <span class="hlt">pressure</span> of 25 MPa. Finally the rock permeability and storage capacity are measured again to assess the evolution of the rock's <span class="hlt">pore</span> fluid properties. For samples with a permeability of 10-20 m2 thermal <span class="hlt">pressurization</span> promotes a 40% decrease in strength. However, after a sequence of three high-speed sliding events, the magnitude of weakening diminishes progressively from 40% to 15%. The weakening events coincide with dilation of the sliding interface. Moreover, the decrease in the weakening degree with progressive fast-slip events suggest that the hydraulic diffusivity may increase locally near the sliding interface during thermal <span class="hlt">pressurization</span>-enhanced slip. This could result from stress- or thermally-induced damage to the host rock, which would perhaps increase both permeability and storage capacity, and so possibly decrease the susceptibility of dynamic weakening due to thermal <span class="hlt">pressurization</span> in subsequent high-speed sliding events.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_8");'>8</a></li> <li><a href="#" onclick='return showDiv("page_9");'>9</a></li> <li class="active"><span>10</span></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_10 --> <div id="page_11" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_9");'>9</a></li> <li><a href="#" onclick='return showDiv("page_10");'>10</a></li> <li class="active"><span>11</span></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="201"> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/biblio/1049070-neutrons-measure-phase-behavior-pores-angstrom-size','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/1049070-neutrons-measure-phase-behavior-pores-angstrom-size"><span>Neutrons measure phase behavior in <span class="hlt">pores</span> at Angstrom size</span></a></p> <p><a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a></p> <p>Bardoel, Agatha A; Melnichenko, Yuri B</p> <p></p> <p>Researchers have measured the phase behavior of green house gases in <span class="hlt">pores</span> at the Angstrom-level, using small angle neutron scattering (SANS) at the Oak Ridge National Laboratory's High Flux Isotope Reactor. Yuri Melnichenko, an instrument scientist on the General Purpose Small Angle Neutron Scattering (GP SANS) Diffractometer at ORNL's High Flux Isotope Reactor, his postdoctoral associate Lilin He and collaborators Nidia Gallego and Cristian Contescu from the Material Sciences Division (ORNL) were engaged in the work. They were studying nanoporous carbons to assess their attractiveness as storage media for hydrogen, with a view to potential use for on-board hydrogen storagemore » for transportation applications. Nanoporous carbons can also serve as electrode material for supercapacitors and batteries. The researchers successfully determined that the most efficiently condensing <span class="hlt">pore</span> size in a carbon nanoporous material for hydrogen storage is less than one nanometer. In a paper recently published by the Journal of the American Chemical Society, the collaborators used small angle neutron scattering to study how hydrogen condenses in small <span class="hlt">pores</span> at ambient temperature. They discovered that the surface-molecule interactions create internal <span class="hlt">pressures</span> in <span class="hlt">pores</span> that may exceed the external gas <span class="hlt">pressure</span> by a factor of up to 50. 'This is an exciting result,' Melnichenko said, 'as you achieve extreme densification in <span class="hlt">pores</span> 'for free', i.e. without spending any energy. These results can be used to guide the development of new carbon adsorbents tailored to maximize hydrogen storage capacities.' Another important factor that defines the adsorption capacity of sub-nanometer <span class="hlt">pores</span> is their shape. In order to get accurate structural information and maximize sorption capacity, it is important that <span class="hlt">pores</span> are small and of approximately uniform size. In collaboration with Drexel University's Yury Gogotsi who supplied the samples, Melnichenko and his collaborators used the GP SANS</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012MMI....18..433H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012MMI....18..433H"><span>Kinetic models of controllable <span class="hlt">pore</span> growth of anodic aluminum oxide membrane</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Huang, Yan; Zeng, Hong-yan; Zhao, Ce; Qu, Ye-qing; Zhang, Pin</p> <p>2012-06-01</p> <p>An anodized Al2O3 (AAO) membrane with apertures about 72 nm in diameter was prepared by two-step anodic oxidation. The appearance and <span class="hlt">pore</span> arrangement of the AAO membrane were characterized by energy dispersive x-ray spectroscopy and scanning electron microscopy. It was confirmed that the <span class="hlt">pores</span> with high <span class="hlt">pore</span> aspect ratio were parallel, well-ordered, and uniform. The kinetics of <span class="hlt">pores</span> growth in the AAO membrane was derived, and the kinetic models showed that <span class="hlt">pores</span> stopped developing when the <span class="hlt">pressure</span> ( σ) trended to equal the surface tension at the end of anodic oxidation. During <span class="hlt">pore</span> expansion, the effects of the oxalic acid concentration and expansion time on the <span class="hlt">pore</span> size were investigated, and the kinetic behaviors were explained with two kinetic models derived in this study. They showed that the <span class="hlt">pore</span> size increased with extended time ( r= G· t+ G'), but decreased with increased concentration ( r = - K·ln c- K') through the derived mathematic formula. Also, the values of G, G', K, and K' were derived from our experimental data.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19830001864','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19830001864"><span><span class="hlt">Pore</span> size engineering applied to starved electrochemical cells and batteries</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Abbey, K. M.; Thaller, L. H.</p> <p>1982-01-01</p> <p>To maximize performance in starved, multiplate cells, the cell design should rely on techniques which widen the volume tolerance characteristics. These involve engineering capillary <span class="hlt">pressure</span> differences between the components of an electrochemical cell and using these forces to promote redistribution of electrolyte to the desired optimum values. This can be implemented in practice by prescribing <span class="hlt">pore</span> size distributions for porous back-up plates, reservoirs, and electrodes. In addition, electrolyte volume management can be controlled by incorporating different <span class="hlt">pore</span> size distributions into the separator. In a nickel/hydrogen cell, the separator must contain <span class="hlt">pores</span> similar in size to the small <span class="hlt">pores</span> of both the nickel and hydrogen electrodes in order to maintain an optimum conductive path for the electrolyte. The <span class="hlt">pore</span> size distributions of all components should overlap in such a way as to prevent drying of the separator and/or flooding of the hydrogen electrode.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=2864933','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=2864933"><span>Relationship of Hypertension, Blood <span class="hlt">Pressure</span>, and Blood <span class="hlt">Pressure</span> Control With White Matter <span class="hlt">Abnormalities</span> in the Women’s Health Initiative Memory Study (WHIMS)—MRI Trial</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Kuller, Lewis H.; Margolis, Karen L.; Gaussoin, Sarah A.; Bryan, Nick R.; Kerwin, Diana; Limacher, Marian; Wassertheil-Smoller, Sylvia; Williamson, Jeff; Robinson, Jennifer G.</p> <p>2010-01-01</p> <p>This paper evaluates the relationship of blood <span class="hlt">pressure</span> (BP) levels at Women’s Health Initiative (WHI) baseline, treatment of hypertension, and white matter <span class="hlt">abnormalities</span> among women in conjugated equine estrogen (CEE) and medroxyprogesterone acetate and CEE-alone arms. The WHI Memory Study—Magnetic Resonance Imaging (WHIMS-MRI) trial scanned 1424 participants. BP levels at baseline were significantly positively related to <span class="hlt">abnormal</span> white matter lesion (WML) volumes. Participants treated for hypertension but who had BP ≥140/90 mm Hg had the greatest amount of WML volumes. Women with untreated BP ≥140/90 mm Hg had intermediate WML volumes. <span class="hlt">Abnormal</span> WML volumes were related to hypertension in most areas of the brain and were greater in the frontal lobe than in the occipital, parietal, or temporal lobes. Level of BP at baseline was strongly related to amount of WML volumes. The results of the study reinforce the relationship of hypertension and BP control and white matter <span class="hlt">abnormalities</span> in the brain. The evidence to date supports tight control of BP levels, especially beginning at younger and middle age as a possible and perhaps only way to prevent dementia. PMID:20433539</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/servlets/purl/1265817','SCIGOV-STC'); return false;" href="https://www.osti.gov/servlets/purl/1265817"><span>Estimation and modeling of coal <span class="hlt">pore</span> accessibility using small angle neutron scattering</span></a></p> <p><a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a></p> <p>Zhang, Rui; Liu, Shimin; Bahadur, Jitendra</p> <p></p> <p>Gas diffusion in coal is controlled by nano-structure of the <span class="hlt">pores</span>. The interconnectivity of <span class="hlt">pores</span> not only determines the dynamics of gas transport in the coal matrix but also influences the mechanical strength. In this study, small angle neutron scattering (SANS) was employed to quantify <span class="hlt">pore</span> accessibility for two coal samples, one of sub-bituminous rank and the other of anthracite rank. Moreover, a theoretical <span class="hlt">pore</span> accessibility model was proposed based on scattering intensities under both vacuum and zero average contrast (ZAC) conditions. Our results show that scattering intensity decreases with increasing gas <span class="hlt">pressure</span> using deuterated methane (CD 4) at lowmore » Q values for both coals. <span class="hlt">Pores</span> smaller than 40 nm in radius are less accessible for anthracite than sub-bituminous coal. On the contrary, when the <span class="hlt">pore</span> radius is larger than 40 nm, the <span class="hlt">pore</span> accessibility of anthracite becomes larger than that of sub-bituminous coal. Only 20% of <span class="hlt">pores</span> are accessible to CD 4 for anthracite and 37% for sub-bituminous coal, where the <span class="hlt">pore</span> radius is 16 nm. For these two coals, <span class="hlt">pore</span> accessibility and <span class="hlt">pore</span> radius follows a power-law relationship.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/pages/biblio/1265817-estimation-modeling-coal-pore-accessibility-using-small-angle-neutron-scattering','SCIGOV-DOEP'); return false;" href="https://www.osti.gov/pages/biblio/1265817-estimation-modeling-coal-pore-accessibility-using-small-angle-neutron-scattering"><span>Estimation and modeling of coal <span class="hlt">pore</span> accessibility using small angle neutron scattering</span></a></p> <p><a target="_blank" href="http://www.osti.gov/pages">DOE PAGES</a></p> <p>Zhang, Rui; Liu, Shimin; Bahadur, Jitendra; ...</p> <p>2015-09-04</p> <p>Gas diffusion in coal is controlled by nano-structure of the <span class="hlt">pores</span>. The interconnectivity of <span class="hlt">pores</span> not only determines the dynamics of gas transport in the coal matrix but also influences the mechanical strength. In this study, small angle neutron scattering (SANS) was employed to quantify <span class="hlt">pore</span> accessibility for two coal samples, one of sub-bituminous rank and the other of anthracite rank. Moreover, a theoretical <span class="hlt">pore</span> accessibility model was proposed based on scattering intensities under both vacuum and zero average contrast (ZAC) conditions. Our results show that scattering intensity decreases with increasing gas <span class="hlt">pressure</span> using deuterated methane (CD 4) at lowmore » Q values for both coals. <span class="hlt">Pores</span> smaller than 40 nm in radius are less accessible for anthracite than sub-bituminous coal. On the contrary, when the <span class="hlt">pore</span> radius is larger than 40 nm, the <span class="hlt">pore</span> accessibility of anthracite becomes larger than that of sub-bituminous coal. Only 20% of <span class="hlt">pores</span> are accessible to CD 4 for anthracite and 37% for sub-bituminous coal, where the <span class="hlt">pore</span> radius is 16 nm. For these two coals, <span class="hlt">pore</span> accessibility and <span class="hlt">pore</span> radius follows a power-law relationship.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017AGUFM.S23C0837B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017AGUFM.S23C0837B"><span>Induced Seismicity in Greeley, CO: The Effects of <span class="hlt">Pore</span> <span class="hlt">Pressure</span> on Seismic Wave Character</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Bogolub, K. R.; Holmes, R.; Sheehan, A. F.; Brown, M. R. M.</p> <p>2017-12-01</p> <p>Since 2013, a series of injection-induced earthquakes has occurred near Greeley, Colorado including a Mw 3.2 event in June 2014. With induced seismicity on the rise, it is important to understand injection-induced earthquakes to improve mitigation efforts. In this research, we analyzed seismograms from a local seismic network to see if there are any notable differences in seismic waveform as a result of changes in <span class="hlt">pore</span> <span class="hlt">pressure</span> from wastewater injection. Catalogued earthquake events from January-June 2017 that were clearly visible on 4 or more stations in the network were used as template events in a subspace detector. Since the template events were constructed using seismograms from a single event, the subspace detector operated similarly to a matched filter and detections had very similar waveforms to the template event. Having these detections ultimately helped us identify similar earthquakes, which gave us better located events for comparison. These detections were then examined and located using a 1D local velocity model. While many of these detections were already catalogued events, we also identified >20 new events by using this detector. Any two events that were matched by the detector, collocated within the error ellipses of both events and at least a month apart temporally were classified as "event pairs". One challenge of this method is that most of the collocated earthquakes occurred in a very narrow time window, which indicates that the events have a tendency to cluster both spatially and temporally. However, we were able to examine an event pair that fit our spatial proximity criteria, and were several months apart (March 3, 2017 and May 8, 2017). We present an examination of propagation velocity and frequency content for these two events specifically to assess if transient changes in <span class="hlt">pore</span> <span class="hlt">pressure</span> had any observable influence on these characteristics. Our preliminary results indicate a slight difference in lag time between P wave and S wave arrivals</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017AGUFM.H53A1428G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017AGUFM.H53A1428G"><span>Basin-Scale Hydrogeological Modeling of the Fort Worth Basin Ellenburger Group for <span class="hlt">Pore</span> <span class="hlt">Pressure</span> Characterization</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Gao, S.; Nicot, J. P.; Dommisse, R. D.; Hennings, P.</p> <p>2017-12-01</p> <p>The Ellenburger Group in the Fort Worth Basin, north-central Texas, is the major target for disposal of flowback and produced water originating from the overlying Barnett Shale gas play. Ellenburger formations of Ordovician age consist of karstic platform carbonates, often dolomitized, with locally high injection potential, and commonly directly overly the Precambrian crystalline basement at depths between6000 and 12,000 ft. In some places sandstones of Cambrian age lie in between the Ellenburger Group and basement. A few localities in or close to the core of the play have experienced seismic activity in the past decade. To better understand naturally occurring and potentially induced seismicity and the relationship to oil and gas operations, a larger team have constructed a 3D hydrogeological model of the Basin with all available well log data, stratigraphic data, petrophysical analysis of the injection intervals, faults from all possible sources including outcrops, controls on permeability anisotropy from outcrops and other data. The model is calibrated with the help of injection <span class="hlt">pressure</span> constraints while honoring injection volume history through 100+ injection wells of the past decades. Major faults, including the east and north model boundaries, are implemented deterministically whereas fractures and minor faults, which considerably enhance the permeability of the carbonate system, are implemented stochastically and history-match the <span class="hlt">pressure</span> data. This work in progress will ultimately provide basin-wide fluid budget analysis and <span class="hlt">pore</span> <span class="hlt">pressure</span> distribution in the Ellenburger formations. It will serve as a fundamental step to assess fault reactivation and basin-wide-seismogenic potential.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/9277520','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/9277520"><span>Protein osmotic <span class="hlt">pressure</span> gradients and microvascular reflection coefficients.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Drake, R E; Dhother, S; Teague, R A; Gabel, J C</p> <p>1997-08-01</p> <p>Microvascular membranes are heteroporous, so the mean osmotic reflection coefficient for a microvascular membrane (sigma d) is a function of the reflection coefficient for each <span class="hlt">pore</span>. Investigators have derived equations for sigma d based on the assumption that the protein osmotic <span class="hlt">pressure</span> gradient across the membrane (delta II) does not vary from <span class="hlt">pore</span> to <span class="hlt">pore</span>. However, for most microvascular membranes, delta II probably does vary from <span class="hlt">pore</span> to <span class="hlt">pore</span>. In this study, we derived a new equation for sigma d. According to our equation, <span class="hlt">pore-to-pore</span> differences in delta II increase the effect of small <span class="hlt">pores</span> and decrease the effect of large <span class="hlt">pores</span> on the overall membrane osmotic reflection coefficient. Thus sigma d for a heteroporous membrane may be much higher than previously derived equations indicate. Furthermore, <span class="hlt">pore-to-pore</span> delta II differences increase the effect of plasma protein osmotic <span class="hlt">pressure</span> to oppose microvascular fluid filtration.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://pubs.er.usgs.gov/publication/70034784','USGSPUBS'); return false;" href="https://pubs.er.usgs.gov/publication/70034784"><span><span class="hlt">Pore</span>-fluid migration and the timing of the 2005 M8.7 Nias earthquake</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Hughes, K.L.H.; Masterlark, Timothy; Mooney, W.D.</p> <p>2011-01-01</p> <p>Two great earthquakes have occurred recently along the Sunda Trench, the 2004 M9.2 Sumatra-Andaman earthquake and the 2005 M8.7 Nias earthquake. These earthquakes ruptured over 1600 km of adjacent crust within 3 mo of each other. We quantitatively present poroelastic deformation analyses suggesting that postseismic fluid flow and recovery induced by the Sumatra-Andaman earthquake advanced the timing of the Nias earthquake. Simple back-slip simulations indicate that the megapascal (MPa)-scale <span class="hlt">pore-pressure</span> recovery is equivalent to 7 yr of interseismic Coulomb stress accumulation near the Nias earthquake hypocenter, implying that <span class="hlt">pore-pressure</span> recovery of the Sumatra-Andaman earthquake advanced the timing of the Nias earthquake by ~7 yr. That is, in the absence of postseismic <span class="hlt">pore-pressure</span> recovery, we predict that the Nias earthquake would have occurred in 2011 instead of 2005. ?? 2011 Geological Society of America.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/28463504','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/28463504"><span>Neutron Scattering Measurements of Carbon Dioxide Adsorption in <span class="hlt">Pores</span> within the Marcellus Shale: Implications for Sequestration.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Stefanopoulos, Konstantinos L; Youngs, Tristan G A; Sakurovs, Richard; Ruppert, Leslie F; Bahadur, Jitendra; Melnichenko, Yuri B</p> <p>2017-06-06</p> <p>Shale is an increasingly viable source of natural gas and a potential candidate for geologic CO 2 sequestration. Understanding the gas adsorption behavior on shale is necessary for the design of optimal gas recovery and sequestration projects. In the present study neutron diffraction and small-angle neutron scattering measurements of adsorbed CO 2 in Marcellus Shale samples were conducted on the Near and InterMediate Range Order Diffractometer (NIMROD) at the ISIS Pulsed Neutron and Muon Source, STFC Rutherford Appleton Laboratory along an adsorption isotherm of 22 °C and <span class="hlt">pressures</span> of 25 and 40 bar. Additional measurements were conducted at approximately 22 and 60 °C at the same <span class="hlt">pressures</span> on the General-Purpose Small-Angle Neutron Scattering (GP-SANS) instrument at Oak Ridge National Laboratory. The structures investigated (<span class="hlt">pores</span>) for CO 2 adsorption range in size from Å level to ∼50 nm. The results indicate that, using the conditions investigated densification or condensation effects occurred in all accessible <span class="hlt">pores</span>. The data suggest that at 22 °C the CO 2 has liquid-like properties when confined in <span class="hlt">pores</span> of around 1 nm radius at <span class="hlt">pressures</span> as low as 25 bar. Many of the 2.5 nm <span class="hlt">pores</span>, 70% of 2 nm <span class="hlt">pores</span>, most of the <1 nm <span class="hlt">pores</span>, and all <span class="hlt">pores</span> <0.25 nm, are inaccessible or closed to CO 2 , suggesting that despite the vast numbers of micropores in shale, the micropores will be unavailable for storage for geologic CO 2 sequestration.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/26903080','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26903080"><span>Homogeneous alignment of liquid crystalline dendrimers confined in a slit-<span class="hlt">pore</span>. A simulation study.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Workineh, Zerihun G; Vanakaras, Alexandros G</p> <p>2016-03-23</p> <p>In this work we present results from isobaric-isothermal (NPT) Monte Carlo simulation studies of model liquid crystalline dendrimer (LCDr) systems confined in a slit-<span class="hlt">pore</span> made of two parallel flat walls. The dendrimers are modelled as a collection of spherical and ellipsoidal particles corresponding to the junction points of the dendritic core and to the mesogenic units respectively. Assuming planar uniform (unidirectional) soft anchoring of the mesogenic units on the substrates we investigate the conformational and alignment properties of the LCDr system at different thermodynamic state points. Tractable coarse grained force fields have been used from our previous work. At low <span class="hlt">pressures</span> the interior of the <span class="hlt">pore</span> is almost empty, since almost all LCDrs are anchored to the substrates forming two-dimensional smectic-like structures with the mesogens aligned along the aligning direction of the substrates. As the <span class="hlt">pressure</span> grows the LCDrs occupy the whole <span class="hlt">pore</span>. However, even at low temperatures, the smectic organization does not transmit in the interior of the <span class="hlt">pore</span> and is preserved for distances of 2-3 mesogenic diameters from the walls. For this reason, the global orientational order decreases with increasing <span class="hlt">pressure</span> (density). In the vicinity (2-3 mesogenic diameters) of the <span class="hlt">pore</span> walls, mesogenic units preserve the smectic structure whose layers are separated by layers of spherical beads. In this region individual LCDrs possess a rod like shape.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016JPCM...28k5002W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016JPCM...28k5002W"><span>Homogeneous alignment of liquid crystalline dendrimers confined in a slit-<span class="hlt">pore</span>. A simulation study</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Workineh, Zerihun G.; Vanakaras, Alexandros G.</p> <p>2016-03-01</p> <p>In this work we present results from isobaric-isothermal (NPT) Monte Carlo simulation studies of model liquid crystalline dendrimer (LCDr) systems confined in a slit-<span class="hlt">pore</span> made of two parallel flat walls. The dendrimers are modelled as a collection of spherical and ellipsoidal particles corresponding to the junction points of the dendritic core and to the mesogenic units respectively. Assuming planar uniform (unidirectional) soft anchoring of the mesogenic units on the substrates we investigate the conformational and alignment properties of the LCDr system at different thermodynamic state points. Tractable coarse grained force fields have been used from our previous work. At low <span class="hlt">pressures</span> the interior of the <span class="hlt">pore</span> is almost empty, since almost all LCDrs are anchored to the substrates forming two-dimensional smectic-like structures with the mesogens aligned along the aligning direction of the substrates. As the <span class="hlt">pressure</span> grows the LCDrs occupy the whole <span class="hlt">pore</span>. However, even at low temperatures, the smectic organization does not transmit in the interior of the <span class="hlt">pore</span> and is preserved for distances of 2-3 mesogenic diameters from the walls. For this reason, the global orientational order decreases with increasing <span class="hlt">pressure</span> (density). In the vicinity (2-3 mesogenic diameters) of the <span class="hlt">pore</span> walls, mesogenic units preserve the smectic structure whose layers are separated by layers of spherical beads. In this region individual LCDrs possess a rod like shape.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015AGUFM.H41C1318A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AGUFM.H41C1318A"><span>Evolution of <span class="hlt">Abnormally</span> Low <span class="hlt">Pressure</span> at Bravo Dome and its Implications for Carbon Capture and Storage (CCS)</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Akhbari, D.; Hesse, M. A.</p> <p>2015-12-01</p> <p>Carbon capture and storage allows reductions of the rapidly rising CO2 from fossil fuel-based power generation, if large storage rates and capacities can be achieved. The injection of large fluid volumes at high rates leads to a build-up of <span class="hlt">pore-pressure</span> in the storage formation that may induce seismicity and compromise the storage security. Many natural CO2 fields in midcontinent US, in contrast, are under-<span class="hlt">pressured</span> rather than over-<span class="hlt">pressured</span> suggesting that natural processes reduce initial over-<span class="hlt">pressures</span> and generate significant under-<span class="hlt">pressures</span>. The question is therefore to understand the sequence of process(es) that allow the initial over-<span class="hlt">pressure</span> to be eliminated and the under-<span class="hlt">pressure</span> to be maintained over geological periods of time. We therefore look into <span class="hlt">pressure</span> evolution in Bravo Dome, one of the largest natural CO2 accumulations in North America, which stores 1.3 Gt of CO2. Bravo Dome is only 580-900 m deep and is divided into several compartments with near gas-static <span class="hlt">pressure</span> (see Figure). The pre-production gas <span class="hlt">pressures</span> in the two main compartments that account for 70% of the mass of CO2 stored at Bravo Dome are more than 6 MPa below hydrostatic <span class="hlt">pressure</span>. Here we show that the under-<span class="hlt">pressure</span> in the Bravo Dome CO2 reservoir is maintained by hydrological compartmentalization over millennial timescales and generated by a combination of processes including cooling, erosional unloading, limited leakage into overlying formations, and CO2 dissolution into brine. Herein, we introduce CO2 dissolution into brine as a new process that reduce gas <span class="hlt">pressure</span> in a compartmentalized reservoir and our results suggest that it may contribute significantly to reduce the initial <span class="hlt">pressure</span> build-up due to injection. Bravo Dome is the first documented case of <span class="hlt">pressure</span> drop due to CO2 dissolution. To have an accurate prediction of <span class="hlt">pressure</span> evolution in Bravo Dome, our models must include geomechanics and thermodynamics for the reservoir while they account for the <span class="hlt">pressure</span></p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012AGUFM.H51G1430M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012AGUFM.H51G1430M"><span><span class="hlt">Pore</span> invasion dynamics during fluid front displacement in porous media determine functional <span class="hlt">pore</span> size distribution and phase entrapment</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Moebius, F.; Or, D.</p> <p>2012-12-01</p> <p>Dynamics of fluid fronts in porous media shape transport properties of the unsaturated zone and affect management of petroleum reservoirs and their storage properties. What appears macroscopically as smooth and continuous motion of a displacement fluid front may involve numerous rapid interfacial jumps often resembling avalanches of invasion events. Direct observations using high-speed camera and <span class="hlt">pressure</span> sensors in sintered glass micro-models provide new insights on the influence of flow rates, <span class="hlt">pore</span> size, and gravity on invasion events and on burst size distribution. Fundamental differences emerge between geometrically-defined <span class="hlt">pores</span> and "functional" <span class="hlt">pores</span> invaded during a single burst (invasion event). The waiting times distribution of individual invasion events and decay times of inertial oscillations (following a rapid interfacial jump) are characteristics of different displacement regimes. An invasion percolation model with gradients and including the role of inertia provide a framework for linking flow regimes with invasion sequences and phase entrapment. Model results were compared with measurements and with early studies on invasion burst sizes and waiting times distribution during slow drainage processes by Måløy et al. [1992]. The study provides new insights into the discrete invasion events and their weak links with geometrically-deduced <span class="hlt">pore</span> geometry. Results highlight factors controlling <span class="hlt">pore</span> invasion events that exert strong influence on macroscopic phenomena such as front morphology and residual phase entrapment shaping hydraulic properties after the passage of a fluid front.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://pubs.er.usgs.gov/publication/70195433','USGSPUBS'); return false;" href="https://pubs.er.usgs.gov/publication/70195433"><span>Neutron scattering measurements of carbon dioxide adsorption in <span class="hlt">pores</span> within the Marcellus Shale: Implications for sequestration</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Stefanopoulos, Konstantinos L.; Youngs, Tristan G. A.; Sakurovs, Richard; Ruppert, Leslie F.; Bahadur, Jitendra; Melnichenko, Yuri B.</p> <p>2017-01-01</p> <p>Shale is an increasingly viable source of natural gas and a potential candidate for geologic CO2sequestration. Understanding the gas adsorption behavior on shale is necessary for the design of optimal gas recovery and sequestration projects. In the present study neutron diffraction and small-angle neutron scattering measurements of adsorbed CO2 in Marcellus Shale samples were conducted on the Near and InterMediate Range Order Diffractometer (NIMROD) at the ISIS Pulsed Neutron and Muon Source, STFC Rutherford Appleton Laboratory along an adsorption isotherm of 22 °C and <span class="hlt">pressures</span> of 25 and 40 bar. Additional measurements were conducted at approximately 22 and 60 °C at the same <span class="hlt">pressures</span> on the General-Purpose Small-Angle Neutron Scattering (GP-SANS) instrument at Oak Ridge National Laboratory. The structures investigated (<span class="hlt">pores</span>) for CO2 adsorption range in size from Å level to ∼50 nm. The results indicate that, using the conditions investigated densification or condensation effects occurred in all accessible <span class="hlt">pores</span>. The data suggest that at 22 °C the CO2 has liquid-like properties when confined in <span class="hlt">pores</span> of around 1 nm radius at <span class="hlt">pressures</span> as low as 25 bar. Many of the 2.5 nm <span class="hlt">pores</span>, 70% of 2 nm <span class="hlt">pores</span>, most of the <1 nm <span class="hlt">pores</span>, and all <span class="hlt">pores</span> <0.25 nm, are inaccessible or closed to CO2, suggesting that despite the vast numbers of micropores in shale, the micropores will be unavailable for storage for geologic CO2 sequestration.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://pubs.er.usgs.gov/publication/70025795','USGSPUBS'); return false;" href="https://pubs.er.usgs.gov/publication/70025795"><span><span class="hlt">Pore</span> space analysis of NAPL distribution in sand-clay media</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Matmon, D.; Hayden, N.J.</p> <p>2003-01-01</p> <p>This paper introduces a conceptual model of clays and non-aqueous phase liquids (NAPLs) at the <span class="hlt">pore</span> scale that has been developed from a mathematical unit cell model, and direct micromodel observation and measurement of clay-containing porous media. The mathematical model uses a unit cell concept with uniform spherical grains for simulating the sand in the sand-clay matrix (???10% clay). Micromodels made with glass slides and including different clay-containing porous media were used to investigate the two clays (kaolinite and montmorillonite) and NAPL distribution within the <span class="hlt">pore</span> space. The results were used to understand the distribution of NAPL advancing into initially saturated sand and sand-clay media, and provided a detailed analysis of the <span class="hlt">pore</span>-scale geometry, <span class="hlt">pore</span> size distribution, NAPL entry <span class="hlt">pressures</span>, and the effect of clay on this geometry. Interesting NAPL saturation profiles were observed as a result of the complexity of the <span class="hlt">pore</span> space geometry with the different packing angles and the presence of clays. The unit cell approach has applications for enhancing the mechanistic understanding and conceptualization, both visually and mathematically, of <span class="hlt">pore</span>-scale processes such as NAPL and clay distribution. ?? 2003 Elsevier Science Ltd. All rights reserved.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/11459339','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/11459339"><span>Fenestral <span class="hlt">pore</span> size in the internal elastic lamina affects transmural flow distribution in the artery wall.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Tada, S; Tarbell, J M</p> <p>2001-06-01</p> <p>Interstitial flow through the subendothelial intima and media of an artery wall was simulated numerically to investigate the water flow distribution through fenestral <span class="hlt">pores</span> which affects the wall shear stress on smooth muscle cells right beneath the internal elastic lamina (IEL). A two-dimensional analysis using the Brinkman model of porous media flow was performed. It was observed that the hydraulic permeability of the intimal layer should be much greater than that of the media in order to predict a reasonable magnitude for the <span class="hlt">pressure</span> drop across the subendothelial intima and IEL (about 23 mostly at a 70 mm Hg luminal <span class="hlt">pressure</span>). When Ki was set equal to the value in the media, this <span class="hlt">pressure</span> drop was unrealistically high. Furthermore, the higher value of Ki produced a nearly uniform distribution of water flow through a simple array of fenestral <span class="hlt">pores</span> all having the same diameters (1.2 microm), whereas when Ki was set at the value in the media, the flow distribution through fenestral <span class="hlt">pores</span> was highly nonuniform and nonphysiologic. A deformable intima model predicted a nonuniform flow distribution at high <span class="hlt">pressure</span> (180 mm Hg). Damage to the IEL was simulated by introducing a large fenestral <span class="hlt">pore</span> (up to 17.8 microm) into the array. A dramatic increase in flow through the large <span class="hlt">pore</span> was observed implying an altered fluid mechanical environment on the smooth muscle cells near the large <span class="hlt">pore</span> which has implications for intimal hyperplasia and atherosclerosis. The model also predicted that the fluid shear stress on the bottom surface of an endothelial cell is on the order of 10 dyne/cm2, a level which can affect cell function.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012EGUGA..1411799V','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012EGUGA..1411799V"><span><span class="hlt">Pore</span> <span class="hlt">Pressure</span> Diffusion as a possible mechanism for the Ag. Ioanis 2001 earthquake swarm activity (Gulf of Corinth, Central Greece).</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Vallianatos, F.; Michas, G.; Papadakis, G.; Sammonds, P.</p> <p>2012-04-01</p> <p>The Gulf of Corinth rift (Central Greece) is one of the most seismotectonically active areas in Europe (Ambraseys and Jackson, 1990; 1997), with an important continental N-S extension of about 13 mm/yr and 6 mm/yr at the west and east part respectively (Clarke et al., 1997a). The seismicity of the area includes 5 main earthquakes of magnitude greater than 5.8 since 1960. In the western part of the rift, where the extension reaches its maximum value, earthquake swarms are often being observed (Bourouis and Cornet, 2009). Such an earthquake crisis has been occurred on 2001 at the southern margin of the west part of the rift. The crisis lasted about 100 days with a major event the Ag. Ioanis earthquake (4.3 Mw) on 8th of April 2001 (Pacchiani and Lyon-Caen, 2010). The possible relation between fluids flow and the observed earthquake swarms at the west part of the Gulf of Corinth rift has been discussed in the works of Bourouis and Cornet (2009) and Pacchiani and Lyon-Caen (2010). In the present work we examine the spatiotemporal properties of the Ag. Ioanis 2001 earthquake swarm, using data from the CRL network (http://crlab.eu/). We connect these properties to a mechanism due to <span class="hlt">pore</span> <span class="hlt">pressure</span> diffusion (Shapiro et al., 1997) and we estimate the hydraulic diffusivity and the permeability of the surrounding rocks. A back front of the seismicity (Parotidis et al., 2004) is also been observed, related to the migration of seismicity and the development of a quiescence region near the area of the initial <span class="hlt">pore</span> <span class="hlt">pressure</span> perturbation. Moreover, anisotropy of the hydraulic diffusivity has been observed, revealing the heterogeneity of the surrounding rocks and the fracture systems. This anisotropy is consistent in direction with the fault zone responsible for the Ag. Ioanis earthquake (Pacchiani and Lyon-Caen, 2010). Our results indicate that fluids flow and <span class="hlt">pore</span> <span class="hlt">pressure</span> perturbations are possible mechanisms for the initiation and the evolution of the Ag. Ioanis 2001</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/29186574','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/29186574"><span>TorsinA dysfunction causes persistent neuronal nuclear <span class="hlt">pore</span> defects.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Pappas, Samuel S; Liang, Chun-Chi; Kim, Sumin; Rivera, CheyAnne O; Dauer, William T</p> <p>2018-02-01</p> <p>A critical challenge to deciphering the pathophysiology of neurodevelopmental disease is identifying which of the myriad <span class="hlt">abnormalities</span> that emerge during CNS maturation persist to contribute to long-term brain dysfunction. Childhood-onset dystonia caused by a loss-of-function mutation in the AAA+ protein torsinA exemplifies this challenge. Neurons lacking torsinA develop transient nuclear envelope (NE) malformations during CNS maturation, but no NE defects are described in mature torsinA null neurons. We find that during postnatal CNS maturation torsinA null neurons develop mislocalized and dysfunctional nuclear <span class="hlt">pore</span> complexes (NPC) that lack NUP358, normally added late in NPC biogenesis. SUN1, a torsinA-related molecule implicated in interphase NPC biogenesis, also exhibits localization <span class="hlt">abnormalities</span>. Whereas SUN1 and associated nuclear membrane <span class="hlt">abnormalities</span> resolve in juvenile mice, NPC defects persist into adulthood. These findings support a role for torsinA function in NPC biogenesis during neuronal maturation and implicate altered NPC function in dystonia pathophysiology. © The Author(s) 2017. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_9");'>9</a></li> <li><a href="#" onclick='return showDiv("page_10");'>10</a></li> <li class="active"><span>11</span></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_11 --> <div id="page_12" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_10");'>10</a></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li class="active"><span>12</span></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="221"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018MS%26E..357a2004Z','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018MS%26E..357a2004Z"><span>Determination of relative phase permeabilities in stochastic model of <span class="hlt">pore</span> channel distribution by diameter</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Zemenkova, M. Y.; Shabarov, A.; Shatalov, A.; Puldas, L.</p> <p>2018-05-01</p> <p>The problem of the <span class="hlt">pore</span> space description and the calculation of relative phase permeabilities (RPP) for two-phase filtration is considered. A technique for constructing a <span class="hlt">pore</span>-network structure for constant and variable channel diameters is proposed. A description of the design model of RPP based on the capillary <span class="hlt">pressure</span> curves is presented taking into account the variability of diameters along the length of <span class="hlt">pore</span> channels. By the example of the calculation analysis for the core samples of the Urnenskoye and Verkhnechonskoye deposits, the possibilities of calculating RPP are shown when using the stochastic distribution of <span class="hlt">pores</span> by diameters and medium-flow diameters.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015AGUFMNG13A1871G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AGUFMNG13A1871G"><span>Veins in Paleo-reservoir as a Natural Indication of Coupled Changes in <span class="hlt">Pore</span> <span class="hlt">Pressure</span> and Stress, Salt Wash Graben of SE Utah, USA</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Gwon, S.; Edwards, P.; Kim, Y. S.</p> <p>2015-12-01</p> <p>Hydrofracturing associated with elevated fluid <span class="hlt">pressure</span> coupled with changes in stress has been crucial in enhancing the production and recovery of hydrocarbons. Furthermore, it is also an important issue to access the efficiency and stability of long-term CO2 geologic storage reservoirs. Veins are mineral-filled extension fractures developed along the plane of σ1-σ2 and perpendicular to σ3, and the fluid <span class="hlt">pressure</span> must exceed σ3applied to the plane when the vein opens. Therefore, vein is a well-known natural analogue for fluid migration in a paleo-reservoir. In the Salt Wash Graben of SE Utah, CO2-charged vein systems hosted in the bleached Entrada Formation are well developed and examined to understand the conditions of fluid <span class="hlt">pressure</span> and stress during the injections of CO2-charged fluid. Based on color and relative cross-cutting relationship in the field, veins are subdivided into two sets; sub-vertical black mineral-rich veins and orthogonal calcite veins that have previously been described as 'grid-lock fractures'. The vein distribution and fluid leakage along through-going fractures in mechanic units allow us to determine the stress regime and driving stress condition through 3D-Mohr circle reconstruction. The results of this statistical analysis for the veins show that the orthogonal veins indicate a 'stress transition' with maximum principal stress direction changing from vertical to NNW-SSE sub-horizontal which coincides with the current regional stress regime. The possible causes of the stress transition can be considered. The process of repeated sealing, reactivation and localization of veins within the bleached zone is a natural indication of a coupled change in <span class="hlt">pore</span> <span class="hlt">pressure</span> and stress in the reservoir. Thus, an understanding of the effect of stress changes due to the volumetric injection of CO2 in the subsurface as well as a knowledge of how pre-existing fractures affect fluid flow with respect to elevated <span class="hlt">pore</span> <span class="hlt">pressures</span> in layered rocks are</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3365342','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3365342"><span>Resistive pulse sensing of magnetic beads and supraparticle structures using tunable <span class="hlt">pores</span></span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Willmott, Geoff R.; Platt, Mark; Lee, Gil U.</p> <p>2012-01-01</p> <p>Tunable <span class="hlt">pores</span> (TPs) have been used for resistive pulse sensing of 1 μm superparamagnetic beads, both dispersed and within a magnetic field. Upon application of this field, magnetic supraparticle structures (SPSs) were observed. Onset of aggregation was most effectively indicated by an increase in the mean event magnitude, with data collected using an automated thresholding method. Simulations enabled discrimination between resistive pulses caused by dimers and individual particles. Distinct but time-correlated peaks were often observed, suggesting that SPSs became separated in <span class="hlt">pressure</span>-driven flow focused at the <span class="hlt">pore</span> constriction. The distinct properties of magnetophoretic and <span class="hlt">pressure</span>-driven transport mechanisms can explain variations in the event rate when particles move through an asymmetric <span class="hlt">pore</span> in either direction, with or without a magnetic field applied. Use of TPs for resistive pulse sensing holds potential for efficient, versatile analysis and measurement of nano- and microparticles, while magnetic beads and particle aggregation play important roles in many prospective biosensing applications. PMID:22662090</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013EGUGA..15.2564T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013EGUGA..15.2564T"><span>Microseismicity Induced by Fluid <span class="hlt">Pressure</span> Drop (Laboratory Study)</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Turuntaev, Sergey; Zenchenko, Evgeny; Melchaeva, Olga</p> <p>2013-04-01</p> <p><span class="hlt">Pore</span> <span class="hlt">pressure</span> change in saturated porous rocks may result in its fracturing (Maury et Fourmaintraux, 1993) and corresponding microseismic event occurrences. Microseismicity due to fluid injection is considered in numerous papers (Maxwell, 2010, Shapiro et al., 2005). Another type of the porous medium fracturing is related with rapid <span class="hlt">pore</span> <span class="hlt">pressure</span> drop at some boundary. The mechanism of such fracturing was considered by (Khristianovich, 1985) as a model of sudden coal blowing and by (Alidibirov, Panov, 1998) as a model of volcano eruptions. If the porous saturated medium has a boundary where it directly contacted with fluid under the high <span class="hlt">pressure</span> (in a hydraulic fracture or in a borehole), and the <span class="hlt">pressure</span> at that boundary is dropped, the conditions for tensile cracks can be achieved at some distance from the boundary. In the paper, the results of experimental study of saturated porous sample fracturing due to <span class="hlt">pore</span> <span class="hlt">pressure</span> rapid drop are discussed. The samples (82 mm high, ∅60 mm) were made of quartz sand, which was cemented by "liquid glass" glue with mass fraction 1%. The sample (porosity 35%, uniaxial unconfined compression strength 2.5 MPa) was placed in a mould and saturated by oil. The upper end of the sample contacted with the mould upper lid, the lower end contacted with fluid. The fluid <span class="hlt">pressure</span> was increased to 10 MPa and then discharged through the bottom nipple. The <span class="hlt">pressure</span> increases/drops were repeated 30-50 times. <span class="hlt">Pore</span> <span class="hlt">pressure</span> and acoustic emission (AE) were registered by transducers mounted into upper and bottom lids of the mould. It was found, that AE sources (corresponded to microfracturing) were spreading from the open end to the closed end of the sample, and that maximal number of AE events was registered at some distance from the opened end. The number of AE pulses increased with every next <span class="hlt">pressure</span> drop, meanwhile the number of pulses with high amplitudes diminished. It was found that AE maximal rate corresponded to the fluid <span class="hlt">pressure</span></p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013EGUGA..1512249A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013EGUGA..1512249A"><span>Effect of unstable layer depth on the <span class="hlt">pore</span> <span class="hlt">pressure</span> distribution, case study of the Slano Blato landslide (Slovenia)</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Askarinejad, Amin; Secchi, Bandar; Macek, Matej; Petkovsek, Ana; Springman, Sarah</p> <p>2013-04-01</p> <p>The Slano Blato landslide is one of the largest landslides in Slovenia with a volume of more than 1 mio m3 of moving debris. The landslide is located at the border of Triassic limestone and Eocene flysch formations. Flysch is composed of layers of marls and sandstones. The sliding mass consists mainly of clay and clayey gravel of highly weathered and deteriorated flysch, while a minor part represents grains and blocks of limestones. (Petkovšek et al., 2009). The first documentation of an instability event dates back to 1789 and the landslide was reactivated during a heavy rain period in November 2000. Since then, the ground surface level above the unstable material on the upper zones of the landslide is significantly decreasing so that the current slope surface is now more than 10 m below the terrain surveyed in 1998. The new landslide topography results in different <span class="hlt">pore</span> <span class="hlt">pressure</span> distributions in the slope, which were anticipated to have a detrimental effect on the stability and movement regime of the slope. The main goal of this work is to investigate the effect of the overlying debris depth on the <span class="hlt">pore</span> water <span class="hlt">pressure</span> distribution during a predefined precipitation scenario. The behaviour of the unsaturated soil and the effects of fissures in the bedrock are also considered in the analysis. Hydro-mechanical simulations were performed using 2D finite element software (PLAXIS) and numerical results are compared with results from analytical models, which use a 1D steady state formulation for the hydraulic part and a 2D limit equilibrium approach to calculate the safety factors. The numerical studies show significant change in the <span class="hlt">pore</span> water <span class="hlt">pressure</span> distribution in the landslide body with variation of the debris depth. An increase in the debris depth leads to higher suction due to the deeper location of the water table. Higher suction increases landslide stability due to: i) increase of the effective stress and hence the shear strength of the material and ii</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/29170108','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/29170108"><span>A mathematical multiscale model of bone remodeling, accounting for <span class="hlt">pore</span> space-specific mechanosensation.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Pastrama, Maria-Ioana; Scheiner, Stefan; Pivonka, Peter; Hellmich, Christian</p> <p>2018-02-01</p> <p>While bone tissue is a hierarchically organized material, mathematical formulations of bone remodeling are often defined on the level of a millimeter-sized representative volume element (RVE), "smeared" over all types of bone microstructures seen at lower observation scales. Thus, there is no explicit consideration of the fact that the biological cells and biochemical factors driving bone remodeling are actually located in differently sized <span class="hlt">pore</span> spaces: active osteoblasts and osteoclasts can be found in the vascular <span class="hlt">pores</span>, whereas the lacunar <span class="hlt">pores</span> host osteocytes - bone cells originating from former osteoblasts which were then "buried" in newly deposited extracellular bone matrix. We here propose a mathematical description which considers size and shape of the <span class="hlt">pore</span> spaces where the biological and biochemical events take place. In particular, a previously published systems biology formulation, accounting for biochemical regulatory mechanisms such as the rank-rankl-opg pathway, is cast into a multiscale framework coupled to a poromicromechanical model. The latter gives access to the vascular and lacunar <span class="hlt">pore</span> <span class="hlt">pressures</span> arising from macroscopic loading. Extensive experimental data on the biological consequences of this loading strongly suggest that the aforementioned <span class="hlt">pore</span> <span class="hlt">pressures</span>, together with the loading frequency, are essential drivers of bone remodeling. The novel approach presented here allows for satisfactory simulation of the evolution of bone tissue under various loading conditions, and for different species; including scenarios such as mechanical dis- and overuse of murine and human bone, or in osteocyte-free bone. Copyright © 2017 Elsevier Inc. All rights reserved.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016EGUGA..18.2248X','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016EGUGA..18.2248X"><span>A new method of evaluating tight gas sands <span class="hlt">pore</span> structure from nuclear magnetic resonance (NMR) logs</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Xiao, Liang; Mao, Zhi-qiang; Xie, Xiu-hong</p> <p>2016-04-01</p> <p>Tight gas sands always display such characteristics of ultra-low porosity, permeability, high irreducible water, low resistivity contrast, complicated <span class="hlt">pore</span> structure and strong heterogeneity, these make that the conventional methods are invalid. Many effective gas bearing formations are considered as dry zones or water saturated layers, and cannot be identified and exploited. To improve tight gas sands evaluation, the best method is quantitative characterizing rock <span class="hlt">pore</span> structure. The mercury injection capillary <span class="hlt">pressure</span> (MICP) curves are advantageous in predicting formation <span class="hlt">pore</span> structure. However, the MICP experimental measurements are limited due to the environment and economy factors, this leads formation <span class="hlt">pore</span> structure cannot be consecutively evaluated. Nuclear magnetic resonance (NMR) logs are considered to be promising in evaluating rock <span class="hlt">pore</span> structure. Generally, to consecutively quantitatively evaluate tight gas sands <span class="hlt">pore</span> structure, the best method is constructing pseudo Pc curves from NMR logs. In this paper, based on the analysis of lab experimental results for 20 core samples, which were drilled from tight gas sandstone reservoirs of Sichuan basin, and simultaneously applied for lab MICP and NMR measurements, the relationships of piecewise power function between nuclear magnetic resonance (NMR) transverse relaxation T2 time and <span class="hlt">pore</span>-throat radius Rc are established. A novel method, which is used to transform NMR reverse cumulative curve as pseudo capillary <span class="hlt">pressure</span> (Pc) curve is proposed, and the corresponding model is established based on formation classification. By using this model, formation pseudo Pc curves can be consecutively synthesized. The <span class="hlt">pore</span> throat radius distribution, and <span class="hlt">pore</span> structure evaluation parameters, such as the average <span class="hlt">pore</span> throat radius (Rm), the threshold <span class="hlt">pressure</span> (Pd), the maximum <span class="hlt">pore</span> throat radius (Rmax) and so on, can also be precisely extracted. After this method is extended into field applications, several tight gas</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017AGUFM.H13E1430W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017AGUFM.H13E1430W"><span>A Three-Dimensional <span class="hlt">Pore</span>-Scale Model for Non-Wetting Phase Mobilization with Ferrofluid</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Wang, N.; Prodanovic, M.</p> <p>2017-12-01</p> <p>Ferrofluid, a stable dispersion of paramagnetic nanoparticles in water, can generate a distributed <span class="hlt">pressure</span> difference across the phase interface in an immiscible two-phase flow under an external magnetic field. In water-wet porous media, this non-uniform <span class="hlt">pressure</span> difference may be used to mobilize the non-wetting phase, e.g. oil, trapped in the <span class="hlt">pores</span>. Previous numerical work by Soares et al. of two-dimensional single-<span class="hlt">pore</span> model showed enhanced non-wetting phase recovery with water-based ferrofluid under certain magnetic field directions and decreased recovery under other directions. However, the magnetic field selectively concentrates in the high magnetic permeability ferrofluid which fills the small corners between the non-wetting phase and the solid wall. The magnetic field induced <span class="hlt">pressure</span> is proportional to the square of local magnetic field strength and its normal component, and makes a significant impact on the non-wetting phase deformation. The two-dimensional model omitted the effect of most of these corners and is not sufficient to compute the magnetic-field-induced <span class="hlt">pressure</span> difference or to predict the non-wetting blob deformation. Further, it is not clear that 3D effects on magnetic field in an irregular geometry can be approximated in 2D. We present a three-dimensional immiscible two-phase flow model to simulate the deformation of a non-wetting liquid blob in a single <span class="hlt">pore</span> filled with a ferrofluid under a uniform external magnetic field. The ferrofluid is modeled as a uniform single phase because the nanoparticles are 104 times smaller than the <span class="hlt">pore</span>. The open source CFD solver library OpenFOAM is used for the simulations based on the volume of fluid method. Simulations are performed in a converging-diverging channel model on different magnetic field direction, different initial oil saturations, and different <span class="hlt">pore</span> shapes. Results indicate that the external magnetic field always stretches the non-wetting blob away from the solid channel wall. A magnetic</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016JAG...135..375K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016JAG...135..375K"><span>Study into the correlation of dominant <span class="hlt">pore</span> throat size and SIP relaxation frequency</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kruschwitz, Sabine; Prinz, Carsten; Zimathies, Annett</p> <p>2016-12-01</p> <p>There is currently a debate within the SIP community about the characteristic textural length scale controlling relaxation time of consolidated porous media. One idea is that the relaxation time is dominated by the <span class="hlt">pore</span> throat size distribution or more specifically the modal <span class="hlt">pore</span> throat size as determined in mercury intrusion capillary <span class="hlt">pressure</span> tests. Recently new studies on inverting <span class="hlt">pore</span> size distributions from SIP data were published implying that the relaxation mechanisms and controlling length scale are well understood. In contrast new analytical model studies based on the Marshall-Madden membrane polarization theory suggested that two relaxation processes might compete: the one along the short narrow <span class="hlt">pore</span> (the throat) with one across the wider <span class="hlt">pore</span> in case the narrow <span class="hlt">pores</span> become relatively long. This paper presents a first systematically focused study into the relationship of <span class="hlt">pore</span> throat sizes and SIP relaxation times. The generality of predicted trends is investigated across a wide range of materials differing considerably in chemical composition, specific surface and <span class="hlt">pore</span> space characteristics. Three different groups of relaxation behaviors can be clearly distinguished. The different behaviors are related to clay content and type, carbonate content, size of the grains and the wide <span class="hlt">pores</span> in the samples.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/21833002','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/21833002"><span><span class="hlt">Abnormalities</span> in ambulatory blood <span class="hlt">pressure</span> monitoring in hypertensive patients with diabetes.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Gorostidi, Manuel; de la Sierra, Alejandro; González-Albarrán, Olga; Segura, Julián; de la Cruz, Juan J; Vinyoles, Ernest; Llisterri, José L; Aranda, Pedro; Ruilope, Luis M; Banegas, José R</p> <p>2011-11-01</p> <p>Our aim was to assess the ambulatory blood <span class="hlt">pressure</span> monitoring (ABPM) characteristics or patterns in hypertensive patients with diabetes compared with non-diabetic hypertensives. We performed a cross-sectional analysis of a 68,045 patient database from the Spanish Society of Hypertension ABPM Registry, a nation-wide network of >1200 primary-care physicians performing ABPM under standardized conditions in daily practice. We identified 12,600 (18.5%) hypertensive patients with diabetes. When compared with patients without diabetes, diabetic hypertensives exhibited higher systolic blood <span class="hlt">pressure</span> (BP) levels in every ABPM period (daytime 135.4 vs. 131.8, and nighttime 126.0 vs. 121.0 mm Hg, P<0.001 for both) despite they were receiving more antihypertensive drugs (mean number 1.71 vs. 1.23, P<0.001). Consequently, diabetic patients suffered from lack of control of BP more frequently than non-diabetic subjects particularly during the night (65.5% vs. 57.4%, P<0.001). Prevalence of a non-dipping BP profile (64.2% vs. 51.6%, P<0.001) was higher in diabetic patients. In the other hand, prevalence of 'white-coat' hypertension in diabetic patients was 33.0%. We conclude that there was a remarkably high prevalence of alterations in ABPM in patients with diabetes. <span class="hlt">Abnormalities</span> in systolic BP, particularly during the night, and in circadian BP pattern could be linked with the excess of BP-related cardiovascular risk of diabetes. A wider use of ABPM in diabetic patients should be considered.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015mmm..conf...79S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015mmm..conf...79S"><span>Fractal Characteristics of the <span class="hlt">Pore</span> Network in Diatomites Using Mercury Porosimetry and Image Analysis</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Stańczak, Grażyna; Rembiś, Marek; Figarska-Warchoł, Beata; Toboła, Tomasz</p> <p></p> <p>The complex <span class="hlt">pore</span> space considerably affects the unique properties of diatomite and its significant potential for many industrial applications. The <span class="hlt">pore</span> network in the diatomite from the Lower Miocene strata of the Skole nappe (the Jawornik deposit, SE Poland) has been investigated using a fractal approach. The fractal dimension of the <span class="hlt">pore</span>-space volume was calculated using the Menger sponge as a model of a porous body and the mercury porosimetry data in a <span class="hlt">pore</span>-throat diameter range between 10,000 and 10 nm. Based on the digital analyses of the two-dimensional images from thin sections taken under a scanning electron microscope at the backscattered electron mode at different magnifications, the authors tried to quantify the <span class="hlt">pore</span> spaces of the diatomites using the box counting method. The results derived from the analyses of the <span class="hlt">pore</span>-throat diameter distribution using mercury porosimetry have revealed that the <span class="hlt">pore</span> space of the diatomite has the bifractal structure in two separated ranges of the <span class="hlt">pore</span>-throat diameters considerably smaller than the <span class="hlt">pore</span>-throat sizes corresponding to threshold <span class="hlt">pressures</span>. Assuming that the fractal dimensions identified for the ranges of the smaller <span class="hlt">pore</span>-throat diameters characterize the overall <span class="hlt">pore</span>-throat network in the Jawornik diatomite, we can set apart the distribution of the <span class="hlt">pore</span>-throat volume (necks) and the <span class="hlt">pore</span> volume from the distribution of the <span class="hlt">pore</span>-space volume (<span class="hlt">pores</span> and necks together).</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016APS..DFDE11005A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016APS..DFDE11005A"><span>Impact of <span class="hlt">pore</span> size variability and network coupling on electrokinetic transport in porous media</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Alizadeh, Shima; Bazant, Martin Z.; Mani, Ali</p> <p>2016-11-01</p> <p>We have developed and validated an efficient and robust computational model to study the coupled fluid and ion transport through electrokinetic porous media, which are exposed to external gradients of <span class="hlt">pressure</span>, electric potential, and concentration. In our approach a porous media is modeled as a network of many <span class="hlt">pores</span> through which the transport is described by the coupled Poisson-Nernst-Planck-Stokes equations. When the <span class="hlt">pore</span> sizes are random, the interactions between various modes of transport may provoke complexities such as concentration polarization shocks and internal flow circulations. These phenomena impact mixing and transport in various systems including deionization and filtration systems, supercapacitors, and lab-on-a-chip devices. In this work, we present simulations of massive networks of <span class="hlt">pores</span> and we demonstrate the impact of <span class="hlt">pore</span> size variation, and <span class="hlt">pore-pore</span> coupling on the overall electrokinetic transport in porous media.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/pages/biblio/1416302-pore-scale-lattice-boltzmann-simulation-micro-gaseous-flow-considering-surface-diffusion-effect','SCIGOV-DOEP'); return false;" href="https://www.osti.gov/pages/biblio/1416302-pore-scale-lattice-boltzmann-simulation-micro-gaseous-flow-considering-surface-diffusion-effect"><span><span class="hlt">Pore</span>-scale lattice Boltzmann simulation of micro-gaseous flow considering surface diffusion effect</span></a></p> <p><a target="_blank" href="http://www.osti.gov/pages">DOE PAGES</a></p> <p>Wang, Junjian; Kang, Qinjun; Chen, Li; ...</p> <p>2016-11-21</p> <p>Some recent studies have shown that adsorbed gas and its surface diffusion have profound influence on micro-gaseous flow through organic <span class="hlt">pores</span> in shale gas reservoirs. Here, a multiple-relaxation-time (MRT) LB model is adopted to estimate the apparent permeability of organic shale and a new boundary condition, which combines Langmuir adsorption theory with Maxwellian diffusive reflection boundary condition, is proposed to capture gas slip and surface diffusion of adsorbed gas. The simulation results match well with previous studies carried out using Molecular Dynamics (MD) and show that Maxwell slip boundary condition fails to characterize gas transport in the near wall regionmore » under the influence of the adsorbed gas. The total molar flux can be either enhanced or reduced depending on variations in adsorbed gas coverage and surface diffusion velocity. The effects of <span class="hlt">pore</span> width, <span class="hlt">pressure</span> as well as Langmuir properties on apparent permeability of methane transport in organic <span class="hlt">pores</span> are further studied. It is found that the surface transport plays a significant role in determining the apparent permeability, and the variation of apparent permeability with <span class="hlt">pore</span> size and <span class="hlt">pressure</span> is affected by the adsorption and surface diffusion.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016NatSR...636919C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016NatSR...636919C"><span><span class="hlt">Pore</span> structure characterization of Chang-7 tight sandstone using MICP combined with N2GA techniques and its geological control factors</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Cao, Zhe; Liu, Guangdi; Zhan, Hongbin; Li, Chaozheng; You, Yuan; Yang, Chengyu; Jiang, Hang</p> <p>2016-11-01</p> <p>Understanding the <span class="hlt">pore</span> networks of unconventional tight reservoirs such as tight sandstones and shales is crucial for extracting oil/gas from such reservoirs. Mercury injection capillary <span class="hlt">pressure</span> (MICP) and N2 gas adsorption (N2GA) are performed to evaluate <span class="hlt">pore</span> structure of Chang-7 tight sandstone. Thin section observation, scanning electron microscope, grain size analysis, mineral composition analysis, and porosity measurement are applied to investigate geological control factors of <span class="hlt">pore</span> structure. Grain size is positively correlated with detrital mineral content and grain size standard deviation while negatively related to clay content. Detrital mineral content and grain size are positively correlated with porosity, <span class="hlt">pore</span> throat radius and withdrawal efficiency and negatively related to capillary <span class="hlt">pressure</span> and <span class="hlt">pore</span>-to-throat size ratio; while interstitial material is negatively correlated with above mentioned factors. Well sorted sediments with high debris usually possess strong compaction resistance to preserve original <span class="hlt">pores</span>. Although many inter-crystalline <span class="hlt">pores</span> are produced in clay minerals, this type of <span class="hlt">pores</span> is not the most important contributor to porosity. Besides this, <span class="hlt">pore</span> shape determined by N2GA hysteresis loop is consistent with SEM observation on clay inter-crystalline <span class="hlt">pores</span> while BJH <span class="hlt">pore</span> volume is positively related with clay content, suggesting N2GA is suitable for describing clay inter-crystalline <span class="hlt">pores</span> in tight sandstones.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/28054663','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/28054663"><span>Thermal separation of soil particles from thermal conductivity measurement under various air <span class="hlt">pressures</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Lu, Sen; Ren, Tusheng; Lu, Yili; Meng, Ping; Zhang, Jinsong</p> <p>2017-01-05</p> <p>The thermal conductivity of dry soils is related closely to air <span class="hlt">pressure</span> and the contact areas between solid particles. In this study, the thermal conductivity of two-phase soil systems was determined under reduced and increased air <span class="hlt">pressures</span>. The thermal separation of soil particles, i.e., the characteristic dimension of the <span class="hlt">pore</span> space (d), was then estimated based on the relationship between soil thermal conductivity and air <span class="hlt">pressure</span>. Results showed that under both reduced and increased air <span class="hlt">pressures</span>, d estimations were significantly larger than the geometrical mean separation of solid particles (D), which suggested that conductive heat transfer through solid particles dominated heat transfer in dry soils. The increased air <span class="hlt">pressure</span> approach gave d values lower than that of the reduced air <span class="hlt">pressure</span> method. With increasing air <span class="hlt">pressure</span>, more collisions between gas molecules and solid surface occurred in micro-<span class="hlt">pores</span> and intra-aggregate <span class="hlt">pores</span> due to the reduction of mean free path of air molecules. Compared to the reduced air <span class="hlt">pressure</span> approach, the increased air <span class="hlt">pressure</span> approach expressed more micro-<span class="hlt">pore</span> structure attributes in heat transfer. We concluded that measuring thermal conductivity under increased air <span class="hlt">pressure</span> procedures gave better-quality d values, and improved soil micro-<span class="hlt">pore</span> structure estimation.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5150636','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5150636"><span>Isolated <span class="hlt">pores</span> dissected from human two-<span class="hlt">pore</span> channel 2 are functional</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Penny, Christopher J.; Rahman, Taufiq; Sula, Altin; Miles, Andrew J.; Wallace, B. A.; Patel, Sandip</p> <p>2016-01-01</p> <p>Multi-domain voltage-gated ion channels appear to have evolved through sequential rounds of intragenic duplication from a primordial one-domain precursor. Whereas modularity within one-domain symmetrical channels is established, little is known about the roles of individual regions within more complex asymmetrical channels where the domains have undergone substantial divergence. Here we isolated and characterised both of the divergent <span class="hlt">pore</span> regions from human TPC2, a two-domain channel that holds a key intermediate position in the evolution of voltage-gated ion channels. In HeLa cells, each <span class="hlt">pore</span> localised to the ER and caused Ca2+ depletion, whereas an ER-targeted <span class="hlt">pore</span> mutated at a residue that inactivates full-length TPC2 did not. Additionally, one of the <span class="hlt">pores</span> expressed at high levels in E. coli. When purified, it formed a stable, folded tetramer. Liposomes reconstituted with the <span class="hlt">pore</span> supported Ca2+ and Na+ uptake that was inhibited by known blockers of full-length channels. Computational modelling of the <span class="hlt">pore</span> corroborated cationic permeability and drug interaction. Therefore, despite divergence, both <span class="hlt">pores</span> are constitutively active in the absence of their partners and retain several properties of the wild-type <span class="hlt">pore</span>. Such symmetrical ‘<span class="hlt">pore</span>-only’ proteins derived from divergent channel domains may therefore provide tractable tools for probing the functional architecture of complex ion channels. PMID:27941820</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/27941820','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/27941820"><span>Isolated <span class="hlt">pores</span> dissected from human two-<span class="hlt">pore</span> channel 2 are functional.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Penny, Christopher J; Rahman, Taufiq; Sula, Altin; Miles, Andrew J; Wallace, B A; Patel, Sandip</p> <p>2016-12-12</p> <p>Multi-domain voltage-gated ion channels appear to have evolved through sequential rounds of intragenic duplication from a primordial one-domain precursor. Whereas modularity within one-domain symmetrical channels is established, little is known about the roles of individual regions within more complex asymmetrical channels where the domains have undergone substantial divergence. Here we isolated and characterised both of the divergent <span class="hlt">pore</span> regions from human TPC2, a two-domain channel that holds a key intermediate position in the evolution of voltage-gated ion channels. In HeLa cells, each <span class="hlt">pore</span> localised to the ER and caused Ca 2+ depletion, whereas an ER-targeted <span class="hlt">pore</span> mutated at a residue that inactivates full-length TPC2 did not. Additionally, one of the <span class="hlt">pores</span> expressed at high levels in E. coli. When purified, it formed a stable, folded tetramer. Liposomes reconstituted with the <span class="hlt">pore</span> supported Ca 2+ and Na + uptake that was inhibited by known blockers of full-length channels. Computational modelling of the <span class="hlt">pore</span> corroborated cationic permeability and drug interaction. Therefore, despite divergence, both <span class="hlt">pores</span> are constitutively active in the absence of their partners and retain several properties of the wild-type <span class="hlt">pore</span>. Such symmetrical '<span class="hlt">pore</span>-only' proteins derived from divergent channel domains may therefore provide tractable tools for probing the functional architecture of complex ion channels.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/servlets/purl/1001046','SCIGOV-STC'); return false;" href="https://www.osti.gov/servlets/purl/1001046"><span><span class="hlt">Pore</span>-scale mechanisms of gas flow in tight sand reservoirs</span></a></p> <p><a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a></p> <p>Silin, D.; Kneafsey, T.J.; Ajo-Franklin, J.B.</p> <p>2010-11-30</p> <p>Tight gas sands are unconventional hydrocarbon energy resource storing large volume of natural gas. Microscopy and 3D imaging of reservoir samples at different scales and resolutions provide insights into the coaredo not significantly smaller in size than conventional sandstones, the extremely dense grain packing makes the <span class="hlt">pore</span> space tortuous, and the porosity is small. In some cases the inter-granular void space is presented by micron-scale slits, whose geometry requires imaging at submicron resolutions. Maximal Inscribed Spheres computations simulate different scenarios of capillary-equilibrium two-phase fluid displacement. For tight sands, the simulations predict an unusually low wetting fluid saturation threshold, at whichmore » the non-wetting phase becomes disconnected. Flow simulations in combination with Maximal Inscribed Spheres computations evaluate relative permeability curves. The computations show that at the threshold saturation, when the nonwetting fluid becomes disconnected, the flow of both fluids is practically blocked. The nonwetting phase is immobile due to the disconnectedness, while the permeability to the wetting phase remains essentially equal to zero due to the <span class="hlt">pore</span> space geometry. This observation explains the Permeability Jail, which was defined earlier by others. The gas is trapped by capillarity, and the brine is immobile due to the dynamic effects. At the same time, in drainage, simulations predict that the mobility of at least one of the fluids is greater than zero at all saturations. A <span class="hlt">pore</span>-scale model of gas condensate dropout predicts the rate to be proportional to the scalar product of the fluid velocity and <span class="hlt">pressure</span> gradient. The narrowest constriction in the flow path is subject to the highest rate of condensation. The <span class="hlt">pore</span>-scale model naturally upscales to the Panfilov's Darcy-scale model, which implies that the condensate dropout rate is proportional to the <span class="hlt">pressure</span> gradient squared. <span class="hlt">Pressure</span> gradient is the greatest near</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/biblio/1049088-pore-size-distribution-accessible-pore-size-distribution-bituminous-coals','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/1049088-pore-size-distribution-accessible-pore-size-distribution-bituminous-coals"><span><span class="hlt">Pore</span> size distribution and accessible <span class="hlt">pore</span> size distribution in bituminous coals</span></a></p> <p><a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a></p> <p>Sakurovs, Richard; He, Lilin; Melnichenko, Yuri B</p> <p>2012-01-01</p> <p>The porosity and <span class="hlt">pore</span> size distribution of coals determine many of their properties, from gas release to their behavior on carbonization, and yet most methods of determining <span class="hlt">pore</span> size distribution can only examine a restricted size range. Even then, only accessible <span class="hlt">pores</span> can be investigated with these methods. Small-angle neutron scattering (SANS) and ultra small-angle neutron scattering (USANS) are increasingly used to characterize the size distribution of all of the <span class="hlt">pores</span> non-destructively. Here we have used USANS/SANS to examine 24 well-characterized bituminous and subbituminous coals: three from the eastern US, two from Poland, one from New Zealand and the restmore » from the Sydney and Bowen Basins in Eastern Australia, and determined the relationships of the scattering intensity corresponding to different <span class="hlt">pore</span> sizes with other coal properties. The range of <span class="hlt">pore</span> radii examinable with these techniques is 2.5 nm to 7 {micro}m. We confirm that there is a wide range of <span class="hlt">pore</span> sizes in coal. The <span class="hlt">pore</span> size distribution was found to be strongly affected by both rank and type (expressed as either hydrogen or vitrinite content) in the size range 250 nm to 7 {micro}m and 5 to 10 nm, but weakly in intermediate regions. The results suggest that different mechanisms control coal porosity on different scales. Contrast-matching USANS and SANS were also used to determine the size distribution of the fraction of the <span class="hlt">pores</span> in these coals that are inaccessible to deuterated methane, CD{sub 4}, at ambient temperature. In some coals most of the small ({approx} 10 nm) <span class="hlt">pores</span> were found to be inaccessible to CD{sub 4} on the time scale of the measurement ({approx} 30 min - 16 h). This inaccessibility suggests that in these coals a considerable fraction of inherent methane may be trapped for extended periods of time, thus reducing the effectiveness of methane release from (or sorption by) these coals. Although the number of small <span class="hlt">pores</span> was less in higher rank coals, the fraction of</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/23069333','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/23069333"><span>Relationship between long-term exposure to low-level arsenic in drinking water and the prevalence of <span class="hlt">abnormal</span> blood <span class="hlt">pressure</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Zhang, Chuanwu; Mao, Guangyun; He, Suxia; Yang, Zuopeng; Yang, Wei; Zhang, Xiaojing; Qiu, Wenting; Ta, Na; Cao, Li; Yang, Hui; Guo, Xiaojuan</p> <p>2013-11-15</p> <p>Arsenic increases the risk and incidence of cardiovascular disease. To explore the impact of long-term exposure to low-level arsenic in drinking water on blood <span class="hlt">pressure</span> including pulse <span class="hlt">pressure</span> (PP) and mean arterial blood <span class="hlt">pressure</span> (MAP), a cross-sectional study was conducted in 2010 in which the blood <span class="hlt">pressure</span> of 405 villagers was measured, who had been drinking water with an inorganic arsenic content <50 μg/L. A multivariate logistic regression model was used to estimate odds ratios and 95% confidence intervals. After adjusting for age, gender, Body Mass Index (BMI), alcohol consumption and smoking, the odds ratios showed a 1.45-fold (95%CI: 0.63-3.35) increase in the group with >30-50 years of arsenic exposure and a 2.95-fold (95%CI: 1.31-6.67) increase in the group with >50 years exposure. Furthermore, the odds ratio for prevalence of <span class="hlt">abnormal</span> PP and MAP were 1.06 (95%CI: 0.24-4.66) and 0.87 (95%CI: 0.36-2.14) in the group with >30-50 years of exposure, and were 2.46 (95%CI: 0.87-6.97) and 3.75 (95%CI: 1.61-8.71) for the group with >50 years exposure, compared to the group with arsenic exposure ≤ 30 years respectively. Significant trends for Hypertension (p<0.0001), PP (p<0.0001) and MAP (p=0.0016) were found. The prevalence of hypertension and <span class="hlt">abnormal</span> PP as well as MAP is marked among a low-level arsenic exposure population, and significantly increases with the duration of arsenic exposure. Copyright © 2012 Elsevier B.V. All rights reserved.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_10");'>10</a></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li class="active"><span>12</span></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_12 --> <div id="page_13" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li class="active"><span>13</span></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="241"> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19970001817&hterms=equilibrium+liquid+vapors&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3Dequilibrium%2Bliquid%2Bvapors','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19970001817&hterms=equilibrium+liquid+vapors&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3Dequilibrium%2Bliquid%2Bvapors"><span>Influence of Two-Phase Thermocapillary Flow on Cryogenic Liquid Retention in Microscopic <span class="hlt">Pores</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Schmidt, G. R.; Nadarajah, A.; Chung, T. J.; Karr, G. R.</p> <p>1994-01-01</p> <p>Previous experiments indicate that the bubble point <span class="hlt">pressure</span> of spacecraft liquid hydrogen acquisition devices is reduced substantially when the ullage is <span class="hlt">pressurized</span> with heated hydrogen vapor. The objective is to determine whether the two-phase thermocapillary convection arising from thermodynamic non-equilibrium along the porous surfaces of such devices could lead to this observed degradation in retention performance. We also examine why retention capability appears to be unaffected by <span class="hlt">pressurization</span> with heated helium or direct heating through the porous structure. Computational assessments based on coupled solution of the flowfield and liquid free surface indicate that for highly wetting fluids in small <span class="hlt">pores</span>, dynamic <span class="hlt">pressure</span> and vapor recoil dictate surface morphology and drive meniscus deformation. With superheating, the two terms exert the same influence on curvature and promote mechanical equilibrium, but with subcooling, the <span class="hlt">pressure</span> distribution produces a suction about the <span class="hlt">pore</span> center-line that degrades retention. This result points to thermocapillary-induced deformation arising from condensation as the cause for retention loss. It also indicates that increasing the level of non-equilibrium by reducing accommodation coefficient restricts deformation and explains why retention failure does not occur with direct screen heating or helium <span class="hlt">pressurization</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5103269','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5103269"><span><span class="hlt">Pore</span> structure characterization of Chang-7 tight sandstone using MICP combined with N2GA techniques and its geological control factors</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Cao, Zhe; Liu, Guangdi; Zhan, Hongbin; Li, Chaozheng; You, Yuan; Yang, Chengyu; Jiang, Hang</p> <p>2016-01-01</p> <p>Understanding the <span class="hlt">pore</span> networks of unconventional tight reservoirs such as tight sandstones and shales is crucial for extracting oil/gas from such reservoirs. Mercury injection capillary <span class="hlt">pressure</span> (MICP) and N2 gas adsorption (N2GA) are performed to evaluate <span class="hlt">pore</span> structure of Chang-7 tight sandstone. Thin section observation, scanning electron microscope, grain size analysis, mineral composition analysis, and porosity measurement are applied to investigate geological control factors of <span class="hlt">pore</span> structure. Grain size is positively correlated with detrital mineral content and grain size standard deviation while negatively related to clay content. Detrital mineral content and grain size are positively correlated with porosity, <span class="hlt">pore</span> throat radius and withdrawal efficiency and negatively related to capillary <span class="hlt">pressure</span> and <span class="hlt">pore</span>-to-throat size ratio; while interstitial material is negatively correlated with above mentioned factors. Well sorted sediments with high debris usually possess strong compaction resistance to preserve original <span class="hlt">pores</span>. Although many inter-crystalline <span class="hlt">pores</span> are produced in clay minerals, this type of <span class="hlt">pores</span> is not the most important contributor to porosity. Besides this, <span class="hlt">pore</span> shape determined by N2GA hysteresis loop is consistent with SEM observation on clay inter-crystalline <span class="hlt">pores</span> while BJH <span class="hlt">pore</span> volume is positively related with clay content, suggesting N2GA is suitable for describing clay inter-crystalline <span class="hlt">pores</span> in tight sandstones. PMID:27830731</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017WRR....53.3424Y','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017WRR....53.3424Y"><span><span class="hlt">Pore</span> network extraction from <span class="hlt">pore</span> space images of various porous media systems</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Yi, Zhixing; Lin, Mian; Jiang, Wenbin; Zhang, Zhaobin; Li, Haishan; Gao, Jian</p> <p>2017-04-01</p> <p><span class="hlt">Pore</span> network extraction, which is defined as the transformation from irregular <span class="hlt">pore</span> space to a simplified network in the form of <span class="hlt">pores</span> connected by throats, is significant to microstructure analysis and network modeling. A physically realistic <span class="hlt">pore</span> network is not only a representation of the <span class="hlt">pore</span> space in the sense of topology and morphology, but also a good tool for predicting transport properties accurately. We present a method to extract <span class="hlt">pore</span> network by employing the centrally located medial axis to guide the construction of maximal-balls-like skeleton where the <span class="hlt">pores</span> and throats are defined and parameterized. To validate our method, various rock samples including sand pack, sandstones, and carbonates were used to extract <span class="hlt">pore</span> networks. The <span class="hlt">pore</span> structures were compared quantitatively with the structures extracted by medial axis method or maximal ball method. The predicted absolute permeability and formation factor were verified against the theoretical solutions obtained by lattice Boltzmann method and finite volume method, respectively. The two-phase flow was simulated through the networks extracted from homogeneous sandstones, and the generated relative permeability curves were compared with the data obtained from experimental method and other numerical models. The results show that the accuracy of our network is higher than that of other networks for predicting transport properties, so the presented method is more reliable for extracting physically realistic <span class="hlt">pore</span> network.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017MsT.........45S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017MsT.........45S"><span>Nano-<span class="hlt">Pore</span> Size Analysis by SAXS Method of Cementitious Mortars Undergoing Delayed Ettringite Formation</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Shekar, Yamini</p> <p></p> <p>This research investigates the nano-scale <span class="hlt">pore</span> structure of cementitious mortars undergoing delayed ettringite formation (DEF) using small angle x-ray scattering (SAXS). DEF has been known to cause expansion and cracking during later ages (around 4000 days) in concrete that has been heat cured at temperatures of 70°C or above. Though DEF normally occurs in heat cured concrete, mass cured concrete can also experience DEF. Large crystalline <span class="hlt">pressures</span> result in smaller <span class="hlt">pore</span> sizes. The objectives of this research are: (1) to investigate why some samples expand early than later expansion, (2) to evaluate the effects of curing conditions and <span class="hlt">pore</span> size distributions at high temperatures, and (3) to assess the evolution of the <span class="hlt">pore</span> size distributions over time. The most important outcome of the research is the <span class="hlt">pore</span> sizes obtained from SAXS were used in the development of a 3-stage model. From the data obtained, the <span class="hlt">pore</span> sizes increase in stage 1 due to initial ettringite formation and in turn filling up the smallest <span class="hlt">pores</span>. Once the critical <span class="hlt">pore</span> size threshold is reached (around 20nm) stage 2 is formed due to cracking which tends to decrease in the <span class="hlt">pore</span> sizes. Finally, in stage 3, the cracking continues, therefore increasing in the <span class="hlt">pore</span> size.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://pubs.er.usgs.gov/publication/70018996','USGSPUBS'); return false;" href="https://pubs.er.usgs.gov/publication/70018996"><span>Limestone characterization to model damage from acidic precipitation: Effect of <span class="hlt">pore</span> structure on mass transfer</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Leith, S.D.; Reddy, M.M.; Irez, W.F.; Heymans, M.J.</p> <p>1996-01-01</p> <p>The <span class="hlt">pore</span> structure of Salem limestone is investigated, and conclusions regarding the effect of the <span class="hlt">pore</span> geometry on modeling moisture and contaminant transport are discussed based on thin section petrography, scanning electron microscopy, mercury intrusion porosimetry, and nitrogen adsorption analyses. These investigations are compared to and shown to compliment permeability and capillary <span class="hlt">pressure</span> measurements for this common building stone. Salem limestone exhibits a bimodal <span class="hlt">pore</span> size distribution in which the larger <span class="hlt">pores</span> provide routes for convective mass transfer of contaminants into the material and the smaller <span class="hlt">pores</span> lead to high surface area adsorption and reaction sites. Relative permeability and capillary <span class="hlt">pressure</span> measurements of the air/water system indicate that Salem limestone exhibits high capillarity end low effective permeability to water. Based on stone characterization, aqueous diffusion and convection are believed to be the primary transport mechanisms for pollutants in this stone. The extent of contaminant accumulation in the stone depends on the mechanism of partitioning between the aqueous and solid phases. The described characterization techniques and modeling approach can be applied to many systems of interest such as acidic damage to limestone, mass transfer of contaminants in concrete and other porous building materials, and modeling pollutant transport in subsurface moisture zones.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018SPIE10496E..17B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018SPIE10496E..17B"><span>Thermo-mechanical mechanism of laser-assisted alteration and stabilization of micro <span class="hlt">pore</span> structure in eye-sclera</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Baum, Olga; Wachsmann-Hogiu, Sebastian; Sobol, Emil</p> <p>2018-02-01</p> <p>Thermo-mechanical effect of laser radiation is a basis of new method of normalization of intraocular <span class="hlt">pressure</span> in glaucomatous eyes due to laser-assisted <span class="hlt">pore</span> formation in eye sclera. Laser-induced creation of <span class="hlt">pores</span> in sclera increases hydraulic permeability. Stability of laser-induced <span class="hlt">pore</span> system is achieved via gas nano-bubbles arisen in the sclera under laser radiation as a result of temperature dependency of gas solubility. The stabilization of laser-induced gas and <span class="hlt">pore</span> systems in the tissue is an important mechanism for a long lasting healing of glaucoma observed in clinical trials with one year follow-up.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://pubs.er.usgs.gov/publication/70046045','USGSPUBS'); return false;" href="https://pubs.er.usgs.gov/publication/70046045"><span>A USANS/SANS study of the accessibility of <span class="hlt">pores</span> in the Barnett Shale to methane and water</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Ruppert, Leslie F.; Sakurovs, Richard; Blach, Tomasz P.; He, Lilin; Melnichenko, Yuri B.; Mildner, David F.; Alcantar-Lopez, Leo</p> <p>2013-01-01</p> <p>Shale is an increasingly important source of natural gas in the United States. The gas is held in fine <span class="hlt">pores</span> that need to be accessed by horizontal drilling and hydrofracturing techniques. Understanding the nature of the <span class="hlt">pores</span> may provide clues to making gas extraction more efficient. We have investigated two Mississippian Barnett Shale samples, combining small-angle neutron scattering (SANS) and ultrasmall-angle neutron scattering (USANS) to determine the <span class="hlt">pore</span> size distribution of the shale over the size range 10 nm to 10 μm. By adding deuterated methane (CD4) and, separately, deuterated water (D2O) to the shale, we have identified the fraction of <span class="hlt">pores</span> that are accessible to these compounds over this size range. The total <span class="hlt">pore</span> size distribution is essentially identical for the two samples. At <span class="hlt">pore</span> sizes >250 nm, >85% of the <span class="hlt">pores</span> in both samples are accessible to both CD4 and D2O. However, differences in accessibility to CD4 are observed in the smaller <span class="hlt">pore</span> sizes (~25 nm). In one sample, CD4 penetrated the smallest <span class="hlt">pores</span> as effectively as it did the larger ones. In the other sample, less than 70% of the smallest <span class="hlt">pores</span> (4, but they were still largely penetrable by water, suggesting that small-scale heterogeneities in methane accessibility occur in the shale samples even though the total porosity does not differ. An additional study investigating the dependence of scattered intensity with <span class="hlt">pressure</span> of CD4 allows for an accurate estimation of the <span class="hlt">pressure</span> at which the scattered intensity is at a minimum. This study provides information about the composition of the material immediately surrounding the <span class="hlt">pores</span>. Most of the accessible (open) <span class="hlt">pores</span> in the 25 nm size range can be associated with either mineral matter or high reflectance organic material. However, a complementary scanning electron microscopy investigation shows that most of the <span class="hlt">pores</span> in these shale samples are contained in the organic components. The neutron scattering results indicate that the <span class="hlt">pores</span> are</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://pubs.er.usgs.gov/publication/70016601','USGSPUBS'); return false;" href="https://pubs.er.usgs.gov/publication/70016601"><span>Assessing the effects of microbial metabolism and metabolities on reservoir <span class="hlt">pore</span> structure</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Udegbunam, E.O.; Adkins, J.P.; Knapp, R.M.; McInerney, M.J.; Tanner, R.S.</p> <p>1991-01-01</p> <p>The effect of microbial treatment on <span class="hlt">pore</span> structure of sandstone and carbonatereservoirs was determined. Understanding how different bacterial strains and their metabolic bioproducts affect reservoir <span class="hlt">pore</span> structure will permit the prudent application of microorganisms for enhanced oil recovery. The microbial strains tested included Clostridium acetobutylicum, a polymer-producing Bacillus strain, and an unidentified halophilic anaerobe that mainly produced acids and gases. Electrical conductivity, absolute permeability, porosity and centrifuge capillary <span class="hlt">pressure</span> were used to examine rock <span class="hlt">pore</span> structures. Modifications of the <span class="hlt">pore</span> structure observed in the laboratory cores included <span class="hlt">pore</span> enlargement due to acid dissolution of carbonates and poare throat reduction due to biomass plugging. This paper shows that careful selection of microbes based on proper understanding of the reservoir petrophysical characteristics is necessary for applications of microbially enhanced oil recovery. These methods and results can be useful to field operators and laboratory researchers involved in design and screening of reservoirs for MEOR. The methods are also applicable in evaluation of formation damage caused by drilling, injection or completion fluids or stimulation caused by acids.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4427103','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4427103"><span><span class="hlt">Pore</span>-Scale Modeling of <span class="hlt">Pore</span> Structure Effects on P-Wave Scattering Attenuation in Dry Rocks</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Li, Tianyang; Qiu, Hao; Wang, Feifei</p> <p>2015-01-01</p> <p>Underground rocks usually have complex <span class="hlt">pore</span> system with a variety of <span class="hlt">pore</span> types and a wide range of <span class="hlt">pore</span> size. The effects of <span class="hlt">pore</span> structure on elastic wave attenuation cannot be neglected. We investigated the <span class="hlt">pore</span> structure effects on P-wave scattering attenuation in dry rocks by <span class="hlt">pore</span>-scale modeling based on the wave theory and the similarity principle. Our modeling results indicate that <span class="hlt">pore</span> size, <span class="hlt">pore</span> shape (such as aspect ratio), and <span class="hlt">pore</span> density are important factors influencing P-wave scattering attenuation in porous rocks, and can explain the variation of scattering attenuation at the same porosity. From the perspective of scattering attenuation, porous rocks can safely suit to the long wavelength assumption when the ratio of wavelength to <span class="hlt">pore</span> size is larger than 15. Under the long wavelength condition, the scattering attenuation coefficient increases as a power function as the <span class="hlt">pore</span> density increases, and it increases exponentially with the increase in aspect ratio. For a certain porosity, rocks with smaller aspect ratio and/or larger <span class="hlt">pore</span> size have stronger scattering attenuation. When the <span class="hlt">pore</span> aspect ratio is larger than 0.5, the variation of scattering attenuation at the same porosity is dominantly caused by <span class="hlt">pore</span> size and almost independent of the <span class="hlt">pore</span> aspect ratio. These results lay a foundation for <span class="hlt">pore</span> structure inversion from elastic wave responses in porous rocks. PMID:25961729</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20080047975&hterms=solute&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3Dsolute','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20080047975&hterms=solute&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3Dsolute"><span>Effect of Stepwise <span class="hlt">Pressure</span> Change on Porosity Evolution during Directional Solidification in Small Cylindrical Channels</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Grugel, R.N.; Lee, C.P.; Cox, M.C.; Blandford, B.T.; Anilkumar, A.V.</p> <p>2008-01-01</p> <p>Controlled directional solidification experiments were performed in capillary channels, using nitrogen-saturated succinonitrile, to examine the effect of an in-situ stepwise processing <span class="hlt">pressure</span> increase on an isolated <span class="hlt">pore</span> evolution. Two experiments were performed using different processing <span class="hlt">pressure</span> input profiles. The results indicate that a processing <span class="hlt">pressure</span> increase has a transient effect on <span class="hlt">pore</span> growth geometry characterized by an initial phase of decreasing <span class="hlt">pore</span> diameter, followed by a recovery phase of increasing <span class="hlt">pore</span> diameter. The experimental results also show that processing <span class="hlt">pressure</span> can be used as a control parameter to either increase or terminate porosity formation. A theoretical model is introduced which indicates that the <span class="hlt">pore</span> formation process is limited by the diffusion of solute-gas through the melt, and that the observed response toa <span class="hlt">pressure</span> increase is attributed to the re-equilibration of solute concentration in the melt associated with the increased melt <span class="hlt">pressure</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/25546834','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/25546834"><span>Drug release through liposome <span class="hlt">pores</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Dan, Nily</p> <p>2015-02-01</p> <p>Electrical, ultrasound and other types of external fields are known to induce the formation of <span class="hlt">pores</span> in cellular and model membranes. This paper examines drug release through field induced liposome <span class="hlt">pores</span> using Monte Carlo simulations. We find that drug release rates vary as a function of <span class="hlt">pore</span> size and spacing, as well as the overall fraction of surface area covered by <span class="hlt">pores</span>: The rate of release from liposomes is found to increase rapidly with <span class="hlt">pore</span> surface coverage, approaching that of the fully ruptured liposome at fractional <span class="hlt">pore</span> areas. For a given <span class="hlt">pore</span> surface coverage, the <span class="hlt">pore</span> size affects the release rate in the limit of low coverage, but not when the <span class="hlt">pores</span> cover a relatively high fraction of the liposome surface area. On the other hand, for a given <span class="hlt">pore</span> size and surface coverage, the distribution of <span class="hlt">pores</span> significantly affects the release in the limit of high surface coverage: The rate of release from a liposome covered with a regularly spaced array of <span class="hlt">pores</span> is, in this limit, higher than the release rate from (most) systems where the <span class="hlt">pores</span> are distributed randomly on the liposome surface. In contrast, there is little effect of the <span class="hlt">pore</span> distribution on release when the <span class="hlt">pore</span> surface coverage is low. The simulation results are in good agreement with the predictions of detailed diffusion models. Copyright © 2014 Elsevier B.V. All rights reserved.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/23432518','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/23432518"><span>Characterization of esophageal <span class="hlt">pressure</span>-flow <span class="hlt">abnormalities</span> in patients with non-obstructive dysphagia and normal manometry findings.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Chen, Chien-Lin; Yi, Chih-Hsun; Liu, Tso-Tsai; Hsu, Ching-Sheng; Omari, Taher I</p> <p>2013-06-01</p> <p>Patients with non-obstructive dysphagia (NOD) report symptoms of impaired esophageal bolus transit without evidence of bolus stasis. In such patients, manometric investigation may diagnose esophageal motility disorders; however, many have normal motor patterns. We hypothesized that patients with NOD would demonstrate evidence of high flow-resistance during bolus passage which in turn would relate to the reporting of bolus hold up perception. Esophageal <span class="hlt">pressure</span>-impedance recordings of 5 mL liquid and viscous swallows from 18 NOD patients (11 male; 19-71 years) and 17 control subjects (9 male; 25-60 years) were analyzed. The relationship between intrabolus <span class="hlt">pressure</span> and bolus flow timing in the esophagus was assessed using the <span class="hlt">pressure</span> flow index (PFI). Bolus perception was assessed swallow by swallow using standardized descriptors. NOD patients were characterized by a higher PFI than controls. The PFI defined a <span class="hlt">pressure</span>-flow <span class="hlt">abnormality</span> in all patients who appeared normal based on the assessment esophageal motor patterns and bolus clearance. The PFI was higher for individual swallows during which subjects reported perception of bolus passage. Bolus flow-resistance is higher in NOD patients compared with controls as well as higher in relation to perception of bolus transit, suggesting the presence of an esophageal motility disorder despite normal findings on conventional analysis. © 2013 Journal of Gastroenterology and Hepatology Foundation and Wiley Publishing Asia Pty Ltd.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017AdWR..109..181B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017AdWR..109..181B"><span><span class="hlt">Pore</span>-scale modeling of wettability effects on CO2-brine displacement during geological storage</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Basirat, Farzad; Yang, Zhibing; Niemi, Auli</p> <p>2017-11-01</p> <p>Wetting properties of reservoir rocks and caprocks can vary significantly, and they strongly influence geological storage of carbon dioxide in deep saline aquifers, during which CO2 is supposed to displace the resident brine and to become permanently trapped. Fundamental understanding of the effect of wettability on CO2-brine displacement is thus important for improving storage efficiency and security. In this study, we investigate the influence of wetting properties on two-phase flow of CO2 and brine at the <span class="hlt">pore</span> scale. A numerical model based on the phase field method is implemented to simulate the two-phase flow of CO2-brine in a realistic <span class="hlt">pore</span> geometry. Our focus is to study the <span class="hlt">pore</span>-scale fluid-fluid displacement mechanisms under different wetting conditions and to quantify the effect of wettability on macroscopic parameters such as residual brine saturation, capillary <span class="hlt">pressure</span>, relative permeability, and specific interfacial area. Our simulation results confirm that both the trapped wetting phase saturation and the normalized interfacial area increase with decreasing contact angle. However, the wetting condition does not appear to influence the CO2 breakthrough time and saturation. We also show that the macroscopic capillary <span class="hlt">pressures</span> based on the <span class="hlt">pressure</span> difference between inlet and outlet can differ significantly from the phase averaging capillary <span class="hlt">pressures</span> for all contact angles when the capillary number is high (log Ca > -5). This indicates that the inlet-outlet <span class="hlt">pressure</span> difference may not be a good measure of the continuum-scale capillary <span class="hlt">pressure</span>. In addition, the results show that the relative permeability of CO2 can be significantly lower in strongly water-wet conditions than in the intermediate-wet conditions.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/12443211','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/12443211"><span>Lattice density functional theory investigation of <span class="hlt">pore</span> shape effects. I. Adsorption in single nonperiodic <span class="hlt">pores</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Malanoski, A P; van Swol, Frank</p> <p>2002-10-01</p> <p>A fully explicit in three dimensions lattice density functional theory is used to investigate adsorption in single nonperiodic <span class="hlt">pores</span>. The effect of varying <span class="hlt">pore</span> shape from the slits and cylinders that are normally simulated was our primary interest. A secondary concern was the results for <span class="hlt">pores</span> with very large diameters. The shapes investigated were square <span class="hlt">pores</span> with or without surface roughness, cylinders, right triangle <span class="hlt">pores</span>, and trapezoidal <span class="hlt">pores</span>. It was found that <span class="hlt">pores</span> with very similar shape factors gave similar results but that the introduction of acute angled corners or very large side ratio lengths in rectangular <span class="hlt">pores</span> gave results that were significantly different. Further, a rectangular <span class="hlt">pore</span> going towards the limit of infinite side ratio does not approach the results of a slit <span class="hlt">pore</span>. In all of these cases, the importance of features that are present for only a small portion of the <span class="hlt">pore</span> is demonstrated.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018JChPh.148e4503D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018JChPh.148e4503D"><span>Effect of <span class="hlt">pore</span> geometry on the compressibility of a confined simple fluid</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Dobrzanski, Christopher D.; Maximov, Max A.; Gor, Gennady Y.</p> <p>2018-02-01</p> <p>Fluids confined in nanopores exhibit properties different from the properties of the same fluids in bulk; among these properties is the isothermal compressibility or elastic modulus. The modulus of a fluid in nanopores can be extracted from ultrasonic experiments or calculated from molecular simulations. Using Monte Carlo simulations in the grand canonical ensemble, we calculated the modulus for liquid argon at its normal boiling point (87.3 K) adsorbed in model silica <span class="hlt">pores</span> of two different morphologies and various sizes. For spherical <span class="hlt">pores</span>, for all the <span class="hlt">pore</span> sizes (diameters) exceeding 2 nm, we obtained a logarithmic dependence of fluid modulus on the vapor <span class="hlt">pressure</span>. Calculation of the modulus at saturation showed that the modulus of the fluid in spherical <span class="hlt">pores</span> is a linear function of the reciprocal <span class="hlt">pore</span> size. The calculation of the modulus of the fluid in cylindrical <span class="hlt">pores</span> appeared too scattered to make quantitative conclusions. We performed additional simulations at higher temperature (119.6 K), at which Monte Carlo insertions and removals become more efficient. The results of the simulations at higher temperature confirmed both regularities for cylindrical <span class="hlt">pores</span> and showed quantitative difference between the fluid moduli in <span class="hlt">pores</span> of different geometries. Both of the observed regularities for the modulus stem from the Tait-Murnaghan equation applied to the confined fluid. Our results, along with the development of the effective medium theories for nanoporous media, set the groundwork for analysis of the experimentally measured elastic properties of fluid-saturated nanoporous materials.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/servlets/purl/919756','SCIGOV-STC'); return false;" href="https://www.osti.gov/servlets/purl/919756"><span>Nanometer-scale imaging and <span class="hlt">pore</span>-scale fluid flow modeling inchalk</span></a></p> <p><a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a></p> <p>Tomutsa, Liviu; Silin, Dmitriy; Radmilovich, Velimir</p> <p>2005-08-23</p> <p>For many rocks of high economic interest such as chalk,diatomite, tight gas sands or coal, nanometer scale resolution is neededto resolve the 3D-<span class="hlt">pore</span> structure, which controls the flow and trapping offluids in the rocks. Such resolutions cannot be achieved with existingtomographic technologies. A new 3D imaging method, based on serialsectioning and using the Focused Ion Beam (FIB) technology has beendeveloped. FIB allows for the milling of layers as thin as 10 nanometersby using accelerated Ga+ ions to sputter atoms from the sample surface.After each milling step, as a new surface is exposed, a 2D image of thissurface is generated. Next,more » the 2D images are stacked to reconstruct the3D <span class="hlt">pore</span> or grain structure. Resolutions as high as 10 nm are achievableusing this technique. A new image processing method uses directmorphological analysis of the <span class="hlt">pore</span> space to characterize thepetrophysical properties of diverse formations. In addition to estimationof the petrophysical properties (porosity, permeability, relativepermeability and capillary <span class="hlt">pressures</span>), the method is used for simulationof fluid displacement processes, such as those encountered in variousimproved oil recovery (IOR) approaches. Computed with the new methodcapillary <span class="hlt">pressure</span> curves are in good agreement with laboratory data. Themethod has also been applied for visualization of the fluid distributionat various saturations from the new FIB data.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/pages/biblio/1208861-extraction-pore-morphology-capillary-pressure-curves-porous-media-from-synchrotron-based-tomography-data','SCIGOV-DOEP'); return false;" href="https://www.osti.gov/pages/biblio/1208861-extraction-pore-morphology-capillary-pressure-curves-porous-media-from-synchrotron-based-tomography-data"><span>Extraction of <span class="hlt">pore</span>-morphology and capillary <span class="hlt">pressure</span> curves of porous media from synchrotron-based tomography data</span></a></p> <p><a target="_blank" href="http://www.osti.gov/pages">DOE PAGES</a></p> <p>Yang, Feifei; Hingerl, Ferdinand F.; Xiao, Xianghui; ...</p> <p>2015-06-03</p> <p>The elevated level of atmospheric carbon dioxide (CO 2) has caused serious concern of the progression of global warming. Geological sequestration is considered as one of the most promising techniques for mitigating the damaging effect of global climate change. Investigations over wide range of length-scales are important for systematic evaluation of the underground formations from prospective CO 2 reservoir. Understanding the relationship between the micro morphology and the observed macro phenomena is even more crucial. Here we show Synchrotron based X-ray micro tomographic study of the morphological buildup of Sandstones. We present a numerical method to extract the <span class="hlt">pore</span> sizesmore » distribution of the porous structure directly, without approximation or complex calculation. We have also demonstrated its capability in predicting the capillary <span class="hlt">pressure</span> curve in a mercury intrusion porosimetry (MIP) measurement. The method presented in this work can be directly applied to the morphological studies of heterogeneous systems in various research fields, ranging from Carbon Capture and Storage, and Enhanced Oil Recovery to environmental remediation in the vadose zone.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014AdWR...74....1F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014AdWR...74....1F"><span>Inertial effects during irreversible meniscus reconfiguration in angular <span class="hlt">pores</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ferrari, Andrea; Lunati, Ivan</p> <p>2014-12-01</p> <p>In porous media, the dynamics of the invading front between two immiscible fluids is often characterized by abrupt reconfigurations caused by local instabilities of the interface. As a prototype of these phenomena we consider the dynamics of a meniscus in a corner as it can be encountered in angular <span class="hlt">pores</span>. We investigate this process in detail by means of direct numerical simulations that solve the Navier-Stokes equations in the <span class="hlt">pore</span> space and employ the Volume of Fluid method (VOF) to track the evolution of the interface. We show that for a quasi-static displacement, the numerically calculated surface energy agrees well with the analytical solutions that we have derived for <span class="hlt">pores</span> with circular and square cross sections. However, the spontaneous reconfigurations are irreversible and cannot be controlled by the injection rate: they are characterized by the amount of surface energy that is spontaneously released and transformed into kinetic energy. The resulting local velocities can be orders of magnitude larger than the injection velocity and they induce damped oscillations of the interface that possess their own time scales and depend only on fluid properties and <span class="hlt">pore</span> geometry. In complex media (we consider a network of cubic <span class="hlt">pores</span>) reconfigurations are so frequent and oscillations last long enough that increasing inertial effects leads to a different fluid distribution by influencing the selection of the next <span class="hlt">pore</span> to be invaded. This calls into question simple <span class="hlt">pore</span>-filling rules based only on capillary forces. Also, we demonstrate that inertial effects during irreversible reconfigurations can influence the work done by the external forces that is related to the <span class="hlt">pressure</span> drop in Darcy's law. This suggests that these phenomena have to be considered when upscaling multiphase flow because local oscillations of the menisci affect macroscopic quantities and modify the constitutive relationships to be used in macro-scale models. These results can be extrapolated to other</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/26220453','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26220453"><span>Poromicromechanics reveals that physiological bone strains induce osteocyte-stimulating lacunar <span class="hlt">pressure</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Scheiner, Stefan; Pivonka, Peter; Hellmich, Christian</p> <p>2016-02-01</p> <p>Mechanical loads which are macroscopically acting onto bony organs, are known to influence the activities of biological cells located in the <span class="hlt">pore</span> spaces of bone, in particular so the signaling and production processes mediated by osteocytes. The exact mechanisms by which osteocytes are actually able to "feel" the mechanical loading and changes thereof, has been the subject of numerous studies, and, while several hypotheses have been brought forth over time, this topic has remained a matter of debate. Relaxation times reported in a recent experimental study of Gardinier et al. (Bone 46(4):1075-1081, 2010) strongly suggest that the lacunar <span class="hlt">pores</span> are likely to experience, during typical physiological load cycles, not only fluid transport, but also undrained conditions. The latter entail the buildup of lacunar <span class="hlt">pore</span> <span class="hlt">pressures</span>, which we here quantify by means of a thorough multiscale modeling approach. In particular, the proposed model is based on classical poroelasticity theory, and able to account for multiple <span class="hlt">pore</span> spaces. First, the model reveals distinct nonlinear dependencies of the resulting lacunar (and vascular) <span class="hlt">pore</span> <span class="hlt">pressures</span> on the underlying bone composition, highlighting the importance of a rigorous multiscale approach for appropriate computation of the aforementioned <span class="hlt">pore</span> <span class="hlt">pressures</span>. Then, the derived equations are evaluated for macroscopic (uniaxial as well as hydrostatic) mechanical loading of physiological magnitude. The resulting model-predicted <span class="hlt">pore</span> <span class="hlt">pressures</span> agree very well with the <span class="hlt">pressures</span> that have been revealed, by means of in vitro studies, to be of adequate magnitude for modulating the responses of biological cells, including osteocytes. This underlines that osteocytes may respond to many types of loading stimuli at the same time, in particular so to fluid flow and hydrostatic <span class="hlt">pressure</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/18249046','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/18249046"><span>The effectiveness of <span class="hlt">pressure</span> garment therapy for the prevention of <span class="hlt">abnormal</span> scarring after burn injury: a meta-analysis.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Anzarut, Alexander; Olson, Jarret; Singh, Prabhjyot; Rowe, Brian H; Tredget, Edward E</p> <p>2009-01-01</p> <p>This study had three objectives. First, to conduct a systematic review to identify the available evidence for the use of <span class="hlt">pressure</span> garment therapy (PGT); second, to assess the quality of the available evidence; and third, to conduct a meta-analysis to quantify the effectiveness of PGT for the prevention of <span class="hlt">abnormal</span> scarring after burn injury. Standard care for the prevention of <span class="hlt">abnormal</span> scarring after burn injury includes <span class="hlt">pressure</span> garment therapy (PGT); however, it is associated with potential patient morbidity and high costs. We hypothesise that an assessment of the available evidence supporting the use of <span class="hlt">pressure</span> garment therapy will aid in directing clinical care and future research. Randomised control trials were identified from CINHAL, EMBASE, MEDLINE, CENTRAL, the 'grey literature' and hand searching of the Proceedings of the American Burn Association. Primary authors and <span class="hlt">pressure</span> garment manufacturers were contacted to identify eligible trials. Bibliographies from included studies and reviews were searched. Study results were pooled to yield weighted mean differences or standardised mean difference and reported using 95% confidence intervals. The review incorporated six unique trials involving 316 patients. Original data from one unpublished trial were included. Overall, studies were considered to be of high methodological quality. The meta-analysis was unable to demonstrate a difference between global assessments of PGT-treated scars and control scars [weighted mean differences (WMD): -0.46; 95% confidence interval (CI): -1.07 to 0.16]. The meta-analysis for scar height showed a small, but statistically significant, decrease in height for the PGT-treated group standardised mean differences (SMD): -0.31; 95% CI: -0.63, 0.00. Results of meta-analyses of secondary outcome measures of scar vascularity, pliability and colour failed to demonstrate a difference between groups. PGT does not appear to alter global scar scores. It does appear to improve scar height</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li class="active"><span>13</span></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_13 --> <div id="page_14" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li class="active"><span>14</span></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="261"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016AGUFM.S31B2732X','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016AGUFM.S31B2732X"><span><span class="hlt">Pore</span> <span class="hlt">pressure</span> may control rupture propagation of the 2001 Mw=7.8 Kokoxili earthquake from the Kunlun fault to the Kunlun Pass fault</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Xiao, J.; Wang, W.; He, J.</p> <p>2016-12-01</p> <p>The 2001 Mw=7.8 Kokoxili earthquake nucleated on the west-east tending Kunlun strike-slip fault in center of the Tibetan plateau. When the rupture propagated eastward near the Xidatan segment of the Kunlun fault, this earthquake jumped to the Kunlun Pass fault, a less matured fault that, due to the geometric orientation, was obviously clamped by the coseismic deformation before its rupture. To investigate the possible mechanism for the rupture jump, we updated the coseismic rupture model from a joint inversion of the geological, geodetic and seismic wave data. Constrained with the rupture process, a three-dimensional finite element model was developed to calculate the failure stress from elastic and poroelastic deformation of the crust during the rupture propagation. Results show that just before the rupture reached the conjunction of the Xidatan segment and the Kunlun Pass fault, the failure stress induced by elastic deformation is indeed larger on Xidatan segment of the Kunlun fault than on the Kunlun Pass fault. However, if the <span class="hlt">pore</span> <span class="hlt">pressure</span> resulted from undrained poroelastic deformation was invoked, the failure stress is significantly increased on the Kunlun Pass fault. Given a reasonable bound on fault friction and on poroelastic parameters, it can be seen that the poroelastic failure stress is 0.3-0.9 Mpa greater on the Kunlun Pass fault than on Xidatan segment of the Kunlun fault. We therefore argue that during the rupture process of the 2001 Mw=7.8 Kokoxili earthquake, <span class="hlt">pore</span> <span class="hlt">pressure</span> may play an important role on controlling the rupture propagation from the Kunlun fault to the Kunlun Pass fault.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/29783083','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/29783083"><span>Adsorption behaviors of supercritical Lennard-Jones fluid in slit-like <span class="hlt">pores</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Li, Yingfeng; Cui, Mengqi; Peng, Bo; Qin, Mingde</p> <p>2018-05-18</p> <p>Understanding the adsorption behaviors of supercritical fluid in confined space is pivotal for coupling the supercritical technology and the membrane separation technology. Based on grand canonical Monte Carlo simulations, the adsorption behaviors of a Lennard-Jones (LJ) fluid in slit-like <span class="hlt">pores</span> at reduced temperatures over the critical temperature, T c *  = 1.312, are investigated; and impacts of the wall-fluid interactions, the <span class="hlt">pore</span> width, and the temperature are taken into account. It is found that even if under supercritical conditions, the LJ fluid can undergo a "vapor-liquid phase transition" in confined space, i.e., the adsorption density undergoes a sudden increase with the bulk density. A greater wall-fluid attractive potential, a smaller <span class="hlt">pore</span> width, and a lower temperature will bring about a stronger confinement effect. Besides, the adsorption <span class="hlt">pressure</span> reaches a local minimum when the bulk density equals to a certain value, independent of the wall-fluid potential or <span class="hlt">pore</span> width. The insights in this work have both practical and theoretical significances. Copyright © 2018 Elsevier Inc. All rights reserved.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/21094192','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/21094192"><span><span class="hlt">Pore</span> formation and <span class="hlt">pore</span> closure in poly(D,L-lactide-co-glycolide) films.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Fredenberg, Susanne; Wahlgren, Marie; Reslow, Mats; Axelsson, Anders</p> <p>2011-03-10</p> <p><span class="hlt">Pore</span> formation and <span class="hlt">pore</span> closure in poly(D,L-lactide-co-glycolide)-based drug delivery systems are two important processes as they control the release of the encapsulated drug. The phenomenon <span class="hlt">pore</span> closure was investigated by studying the effects of the pH and the temperature of the release medium, and the properties of the polymer. Poly(D,L-lactide-co-glycolide) (PLG) films were subjected to a <span class="hlt">pore</span> forming pre-treatment, and then <span class="hlt">pore</span> closure was observed simultaneously with changes in glass transition temperature, wettability (contact angle), water absorption and mass remaining. To further understand the effect of pH, combined <span class="hlt">pore</span> formation and <span class="hlt">pore</span> closure were studied at different pH values. <span class="hlt">Pore</span> closure was increased in a release medium with low pH, with a low-molecular-weight PLG of relatively low degree of hydrophobicity, or at high temperature. <span class="hlt">Pore</span> closure occurred by two different mechanisms, one based on polymer-polymer interactions and one on polymer-water interactions. The mobility of the PLG chains also played an important role. The surface of the PLG films were more porous at pH 5-6 than at lower or higher pH, as <span class="hlt">pore</span> formation was relatively fast and <span class="hlt">pore</span> closure were less pronounced in this pH range. The pH had a significant impact on the porous structure, which should be kept in mind when evaluating experimental results, as the pH may be significantly decreased in vitro, in vivo and in situ. The results also show that the initial porosity is very important when using a high-molecular-weight PLG. Copyright © 2010 Elsevier B.V. All rights reserved.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/29958476','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/29958476"><span>Concentration of Immunoglobulins in Microfiltration Permeates of Skim Milk: Impact of Transmembrane <span class="hlt">Pressure</span> and Temperature on the IgG Transmission Using Different Ceramic Membrane Types and <span class="hlt">Pore</span> Sizes.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Heidebrecht, Hans-Jürgen; Toro-Sierra, José; Kulozik, Ulrich</p> <p>2018-06-28</p> <p>The use of bioactive bovine milk immunoglobulins (Ig) has been found to be an alternative treatment for certain human gastrointestinal diseases. Some methodologies have been developed with bovine colostrum. These are considered in laboratory scale and are bound to high cost and limited availability of the raw material. The main challenge remains in obtaining high amounts of active IgG from an available source as mature cow milk by the means of industrial processes. Microfiltration (MF) was chosen as a process variant, which enables a gentle and effective concentration of the Ig fractions (ca. 0.06% in raw milk) while reducing casein and lactose at the same time. Different microfiltration membranes (ceramic standard and gradient), <span class="hlt">pore</span> sizes (0.14⁻0.8 µm), transmembrane <span class="hlt">pressures</span> (0.5⁻2.5 bar), and temperatures (10, 50 °C) were investigated. The transmission of immunoglobulin G (IgG) and casein during the filtration of raw skim milk (<0.1% fat) was evaluated during batch filtration using a single channel pilot plant. The transmission levels of IgG (~160 kDa) were measured to be at the same level as the reference major whey protein β-Lg (~18 kDa) at all evaluated <span class="hlt">pore</span> sizes and process parameters despite the large difference in molecular mass of both fractions. Ceramic gradient membranes with a <span class="hlt">pore</span> sizes of 0.14 µm showed IgG-transmission rates between 45% to 65% while reducing the casein fraction below 1% in the permeates. Contrary to the expectations, a lower <span class="hlt">pore</span> size of 0.14 µm yielded fluxes up to 35% higher than 0.2 µm MF membranes. It was found that low transmembrane <span class="hlt">pressures</span> benefit the Ig transmission. Upscaling the presented results to a continuous MF membrane process offers new possibilities for the production of immunoglobulin enriched supplements with well-known processing equipment for large scale milk protein fractionation.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4354668','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4354668"><span>Reservoir Condition <span class="hlt">Pore</span>-scale Imaging of Multiple Fluid Phases Using X-ray Microtomography</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Andrew, Matthew; Bijeljic, Branko; Blunt, Martin</p> <p>2015-01-01</p> <p>X-ray microtomography was used to image, at a resolution of 6.6 µm, the <span class="hlt">pore</span>-scale arrangement of residual carbon dioxide ganglia in the <span class="hlt">pore</span>-space of a carbonate rock at <span class="hlt">pressures</span> and temperatures representative of typical formations used for CO2 storage. Chemical equilibrium between the CO2, brine and rock phases was maintained using a high <span class="hlt">pressure</span> high temperature reactor, replicating conditions far away from the injection site. Fluid flow was controlled using high <span class="hlt">pressure</span> high temperature syringe pumps. To maintain representative in-situ conditions within the micro-CT scanner a carbon fiber high <span class="hlt">pressure</span> micro-CT coreholder was used. Diffusive CO2 exchange across the confining sleeve from the <span class="hlt">pore</span>-space of the rock to the confining fluid was prevented by surrounding the core with a triple wrap of aluminum foil. Reconstructed brine contrast was modeled using a polychromatic x-ray source, and brine composition was chosen to maximize the three phase contrast between the two fluids and the rock. Flexible flow lines were used to reduce forces on the sample during image acquisition, potentially causing unwanted sample motion, a major shortcoming in previous techniques. An internal thermocouple, placed directly adjacent to the rock core, coupled with an external flexible heating wrap and a PID controller was used to maintain a constant temperature within the flow cell. Substantial amounts of CO2 were trapped, with a residual saturation of 0.203 ± 0.013, and the sizes of larger volume ganglia obey power law distributions, consistent with percolation theory. PMID:25741751</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/29652841','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/29652841"><span>Electrochemically-Driven Insertion of Biological Nanodiscs into Solid State Membrane <span class="hlt">Pores</span> as a Basis for "<span class="hlt">Pore-In-Pore</span>" Membranes.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Farajollahi, Farid; Seidenstücker, Axel; Altintoprak, Klara; Walther, Paul; Ziemann, Paul; Plettl, Alfred; Marti, Othmar; Wege, Christina; Gliemann, Hartmut</p> <p>2018-04-13</p> <p>Nanoporous membranes are of increasing interest for many applications, such as molecular filters, biosensors, nanofluidic logic and energy conversion devices. To meet high-quality standards, e.g., in molecular separation processes, membranes with well-defined <span class="hlt">pores</span> in terms of <span class="hlt">pore</span> diameter and chemical properties are required. However, the preparation of membranes with narrow <span class="hlt">pore</span> diameter distributions is still challenging. In the work presented here, we demonstrate a strategy, a "<span class="hlt">pore-in-pore</span>" approach, where the conical <span class="hlt">pores</span> of a solid state membrane produced by a multi-step top-down lithography procedure are used as a template to insert precisely-formed biomolecular nanodiscs with exactly defined inner and outer diameters. These nanodiscs, which are the building blocks of tobacco mosaic virus-deduced particles, consist of coat proteins, which self-assemble under defined experimental conditions with a stabilizing short RNA. We demonstrate that the insertion of the nanodiscs can be driven either by diffusion due to a concentration gradient or by applying an electric field along the cross-section of the solid state membrane. It is found that the electrophoresis-driven insertion is significantly more effective than the insertion via the concentration gradient.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://pubs.er.usgs.gov/publication/70042442','USGSPUBS'); return false;" href="https://pubs.er.usgs.gov/publication/70042442"><span>Laboratory triggering of stick-slip events by oscillatory loading in the presence of <span class="hlt">pore</span> fluid with implications for physics of tectonic tremor</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Bartlow, Noel M.; Lockner, David A.; Beeler, Nicholas M.</p> <p>2012-01-01</p> <p>The physical mechanism by which the low-frequency earthquakes (LFEs) that make up portions of tectonic (also called non-volcanic) tremor are created is poorly understood. In many areas of the world, tectonic tremor and LFEs appear to be strongly tidally modulated, whereas ordinary earthquakes are not. Anomalous seismic wave speeds, interpreted as high <span class="hlt">pore</span> fluid <span class="hlt">pressure</span>, have been observed in regions that generate tremor. Here we build upon previous laboratory studies that investigated the response of stick-slip on artificial faults to oscillatory, tide-like loading. These previous experiments were carried out using room-dry samples of Westerly granite, at one effective stress. Here we augment these results with new experiments on Westerly granite, with the addition of varying effective stress using <span class="hlt">pore</span> fluid at two <span class="hlt">pressures</span>. We find that raising <span class="hlt">pore</span> <span class="hlt">pressure</span>, thereby lowering effective stress can significantly increase the degree of correlation of stick-slip to oscillatory loading. We also find other <span class="hlt">pore</span> fluid effects that become important at higher frequencies, when the period of oscillation is comparable to the diffusion time of <span class="hlt">pore</span> fluid into the fault. These results help constrain the conditions at depth that give rise to tidally modulated LFEs, providing confirmation of the effective <span class="hlt">pressure</span> law for triggering and insights into why tremor is tidally modulated while earthquakes are at best only weakly modulated.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/biblio/665157-freeze-thaw-durability-concrete-ice-formation-process-pores','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/665157-freeze-thaw-durability-concrete-ice-formation-process-pores"><span>Freeze-thaw durability of concrete: Ice formation process in <span class="hlt">pores</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a></p> <p>Cai, H.; Liu, X.</p> <p>1998-09-01</p> <p>Freeze-thaw durability of concrete is of great importance to hydraulic structures in cold areas. Study of ice formation process in concrete <span class="hlt">pores</span> is necessary to evaluate the damages in concrete caused by freezing. In this paper, freezing of <span class="hlt">pore</span> solution in concrete exposed to a freeze-thaw cycle is studied by following the change of concrete electrical conductivity with freezing temperatures. Concretes were subjected to freeze-thaw cycles with temperature varying between {minus}0 C and {minus}20 C. In the freezing process, the changing rate of concrete electrical conductivity obviously decreases at about {minus}10 C, indicating that more <span class="hlt">pore</span> solution in concrete freezesmore » above {minus}10 C than below {minus}10C. According to Powers` static hydraulic <span class="hlt">pressure</span> hypothesis, it is thought that frost damage mainly occurs between 0 C and {minus}100 C. To ordinary concrete, frost damages below {minus}10 C are negligible.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/22343900','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/22343900"><span>Piezo proteins are <span class="hlt">pore</span>-forming subunits of mechanically activated channels.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Coste, Bertrand; Xiao, Bailong; Santos, Jose S; Syeda, Ruhma; Grandl, Jörg; Spencer, Kathryn S; Kim, Sung Eun; Schmidt, Manuela; Mathur, Jayanti; Dubin, Adrienne E; Montal, Mauricio; Patapoutian, Ardem</p> <p>2012-02-19</p> <p>Mechanotransduction has an important role in physiology. Biological processes including sensing touch and sound waves require as-yet-unidentified cation channels that detect <span class="hlt">pressure</span>. Mouse Piezo1 (MmPiezo1) and MmPiezo2 (also called Fam38a and Fam38b, respectively) induce mechanically activated cationic currents in cells; however, it is unknown whether Piezo proteins are <span class="hlt">pore</span>-forming ion channels or modulate ion channels. Here we show that Drosophila melanogaster Piezo (DmPiezo, also called CG8486) also induces mechanically activated currents in cells, but through channels with remarkably distinct <span class="hlt">pore</span> properties including sensitivity to the <span class="hlt">pore</span> blocker ruthenium red and single channel conductances. MmPiezo1 assembles as a ∼1.2-million-dalton homo-oligomer, with no evidence of other proteins in this complex. Purified MmPiezo1 reconstituted into asymmetric lipid bilayers and liposomes forms ruthenium-red-sensitive ion channels. These data demonstrate that Piezo proteins are an evolutionarily conserved ion channel family involved in mechanotransduction.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2008WRR....44.6S01A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2008WRR....44.6S01A"><span>Multiphase flow predictions from carbonate <span class="hlt">pore</span> space images using extracted network models</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Al-Kharusi, Anwar S.; Blunt, Martin J.</p> <p>2008-06-01</p> <p>A methodology to extract networks from <span class="hlt">pore</span> space images is used to make predictions of multiphase transport properties for subsurface carbonate samples. The extraction of the network model is based on the computation of the location and sizes of <span class="hlt">pores</span> and throats to create a topological representation of the void space of three-dimensional (3-D) rock images, using the concept of maximal balls. In this work, we follow a multistaged workflow. We start with a 2-D thin-section image; convert it statistically into a 3-D representation of the <span class="hlt">pore</span> space; extract a network model from this image; and finally, simulate primary drainage, waterflooding, and secondary drainage flow processes using a <span class="hlt">pore</span>-scale simulator. We test this workflow for a reservoir carbonate rock. The network-predicted absolute permeability is similar to the core plug measured value and the value computed on the 3-D void space image using the lattice Boltzmann method. The predicted capillary <span class="hlt">pressure</span> during primary drainage agrees well with a mercury-air experiment on a core sample, indicating that we have an adequate representation of the rock's <span class="hlt">pore</span> structure. We adjust the contact angles in the network to match the measured waterflood and secondary drainage capillary <span class="hlt">pressures</span>. We infer a significant degree of contact angle hysteresis. We then predict relative permeabilities for primary drainage, waterflooding, and secondary drainage that agree well with laboratory measured values. This approach can be used to predict multiphase transport properties when wettability and <span class="hlt">pore</span> structure vary in a reservoir, where experimental data is scant or missing. There are shortfalls to this approach, however. We compare results from three networks, one of which was derived from a section of the rock containing vugs. Our method fails to predict properties reliably when an unrepresentative image is processed to construct the 3-D network model. This occurs when the image volume is not sufficient to represent the</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2006AGUFM.G33A0049N','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2006AGUFM.G33A0049N"><span>Stress and <span class="hlt">Pore</span> Fluid <span class="hlt">Pressure</span> Cycles Beneath the Seismogenic Layer Recorded by Veins</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Nüchter, J. A.; Stöckhert, B.</p> <p>2006-12-01</p> <p>Metamorphic rocks approaching the crustal scale brittle-ductile transition (BDT) during exhumation are expected to become increasingly affected by short term stress fluctuations related to seismic activity in the overlying seismogenic layer, while still residing in a long-term viscous environment. The (micro-)structural record of monogenetic syntaxial quartz veins in metamorphic rocks from southern Evia, Greece, yields insight into the processes and conditions just beneath the long-term BDT at temperatures of about 300 to 350° C. The following features are characteristic: 1) The veins crosscut the foliation and all syn-metamorphic structures; 2) the veins have formed from tensile fractures, with a typical length on the order of 10-1 to 101 m; 3) some veins branch symmetrically with an aperture angle of 30°, which is interpreted to indicate high crack propagation rates similar to Raleigh wave speed; 4) the veins formed during a single sealing stage by mineral precipitation in open cavities; 5) the veins show a low aspect ratio of about 10 to 100 and a characteristic lenticular shape, controlled by distributed ductile deformation of the host rock, with vein-parallel shortening by typically less than 1 %; 6) the intensity of crystal plastic deformation in the vein quartz decreases from the vein walls towards the center; 7) fluid inclusions trapped in the vein quartz record a time series of <span class="hlt">pore</span> fluid <span class="hlt">pressure</span> (Pf) evolution during progressive sealing, with low Pf at the vein walls (early stage) to high Pf in the vein core (final stage). These features indicate: Opening of the fractures commenced immediately after crack arrest, controlled by ductile deformation of the host rock at temperatures between about 300 and 350° C. The crack opening rate exceeded the rate of sealing, so that the quartz crystals grew into an open cavity. For opening of cracks, the effective stress on the fracture walls must be tensile and the fluid <span class="hlt">pressure</span> must be similar to that of the</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://aapgbull.geoscienceworld.org/cgi/content/extract/95/8/1448','USGSPUBS'); return false;" href="http://aapgbull.geoscienceworld.org/cgi/content/extract/95/8/1448"><span><span class="hlt">Pore</span>-throat sizes in sandstones, siltstones, and shales: Reply</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Nelson, Philip H.</p> <p>2011-01-01</p> <p>In his discussion of my article (Nelson, 2009), W. K. Camp takes issue with the concept that buoyancy is not the dominant force in forming and maintaining the distribution of gas in tight-gas accumulations (Camp, 2011). I will restrict my response to the issues he raised regarding buoyant versus nonbuoyant drive and to a few comments regarding water saturation and production. I claim that the <span class="hlt">pressure</span> generated in petroleum source rocks (Pg), instead of the buoyancy <span class="hlt">pressure</span> (Pb), provides the energy to charge most tight sandstones with gas. The arguments are fourfold: (1) buoyant columns of sufficient height seldom exist in low-permeability sand-shale sequences, (2) tight-gas systems display a <span class="hlt">pressure</span> profile that declines instead of increases upward, (3) gas is pervasive in overpressured systems, and (4) source rocks can generate <span class="hlt">pore</span> <span class="hlt">pressures</span> sufficiently high to charge tight sandstones.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2008AGUFM.T51A1856L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2008AGUFM.T51A1856L"><span>Energy Dissipation in Calico Hills Tuff due to <span class="hlt">Pore</span> Collapse</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Lockner, D. A.; Morrow, C. A.</p> <p>2008-12-01</p> <p>Laboratory tests indicate that the weakest portions of the Calico Hills tuff formation are at or near yield stress under in situ conditions and that the energy expended during incremental loading can be more than 90 percent irrecoverable. The Calico Hills tuff underlies the Yucca Mountain waste repository site at a depth of 400 to 500 m within the unsaturated zone. The formation is highly variable in the degree of both vitrification and zeolitization. Since 1980, a number of boreholes penetrated this formation to provide site characterization for the YM repository. In the past, standard strength measurements were conducted on core samples from the drillholes. However, a significant sampling bias occurred in that tests were preferentially conducted on highly vitrified, higher-strength samples. In fact, the most recent holes were drilled with a dry coring technique that would pulverize the weakest layers, leaving none of this material for testing. We have re-examined Calico Hills samples preserved at the YM Core Facility and selected the least vitrified examples (some cores exceeded 50 percent porosity) for mechanical testing. Three basic tests were performed: (i) hydrostatic crushing tests (to 350 MPa), (ii) standard triaxial deformation tests at constant effective confining <span class="hlt">pressure</span> (to 70 MPa), and (iii) plane strain tests with initial conditions similar to in situ stresses. In all cases, constant <span class="hlt">pore</span> <span class="hlt">pressure</span> of 10 MPa was maintained using argon gas as a <span class="hlt">pore</span> fluid and <span class="hlt">pore</span> volume loss was monitored during deformation. The strongest samples typically failed along discrete fractures in agreement with standard Mohr-Coulomb failure. The weaker, high porosity samples, however, would fail by pure <span class="hlt">pore</span> collapse or by a combined shear-induced compaction mechanism similar to failure mechanisms described for porous sandstones and carbonates. In the plane-strain experiments, energy dissipation due to <span class="hlt">pore</span> collapse was determined for eventual input into dynamic wave</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5618127','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5618127"><span>The Effect of the <span class="hlt">Pore</span> Entrance on Particle Motion in Slit <span class="hlt">Pores</span>: Implications for Ultrathin Membranes</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Delavari, Armin; Baltus, Ruth</p> <p>2017-01-01</p> <p>Membrane rejection models generally neglect the effect of the <span class="hlt">pore</span> entrance on intrapore particle transport. However, entrance effects are expected to be particularly important with ultrathin membranes, where membrane thickness is typically comparable to <span class="hlt">pore</span> size. In this work, a 2D model was developed to simulate particle motion for spherical particles moving at small Re and infinite Pe from the reservoir outside the <span class="hlt">pore</span> into a slit <span class="hlt">pore</span>. Using a finite element method, particles were tracked as they accelerated across the <span class="hlt">pore</span> entrance until they reached a steady velocity in the <span class="hlt">pore</span>. The axial position in the <span class="hlt">pore</span> where particle motion becomes steady is defined as the particle entrance length (PEL). PELs were found to be comparable to the fluid entrance length, larger than the <span class="hlt">pore</span> size and larger than the thickness typical of many ultrathin membranes. Results also show that, in the absence of particle diffusion, hydrodynamic particle–membrane interactions at the <span class="hlt">pore</span> mouth result in particle “funneling” in the <span class="hlt">pore</span>, yielding cross-<span class="hlt">pore</span> particle concentration profiles focused at the <span class="hlt">pore</span> centerline. The implications of these phenomena on rejection from ultrathin membranes are examined. PMID:28796197</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2001PNAS...98.2634M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2001PNAS...98.2634M"><span>Cardiovascular <span class="hlt">abnormalities</span> with normal blood <span class="hlt">pressure</span> in tissue kallikrein-deficient mice</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Meneton, Pierre; Bloch-Faure, May; Hagege, Albert A.; Ruetten, Hartmut; Huang, Wei; Bergaya, Sonia; Ceiler, Debbie; Gehring, Doris; Martins, Isabelle; Salmon, Georges; Boulanger, Chantal M.; Nussberger, Jürg; Crozatier, Bertrand; Gasc, Jean-Marie; Heudes, Didier; Bruneval, Patrick; Doetschman, Tom; Ménard, Joël; Alhenc-Gelas, François</p> <p>2001-02-01</p> <p>Tissue kallikrein is a serine protease thought to be involved in the generation of bioactive peptide kinins in many organs like the kidneys, colon, salivary glands, pancreas, and blood vessels. Low renal synthesis and urinary excretion of tissue kallikrein have been repeatedly linked to hypertension in animals and humans, but the exact role of the protease in cardiovascular function has not been established largely because of the lack of specific inhibitors. This study demonstrates that mice lacking tissue kallikrein are unable to generate significant levels of kinins in most tissues and develop cardiovascular <span class="hlt">abnormalities</span> early in adulthood despite normal blood <span class="hlt">pressure</span>. The heart exhibits septum and posterior wall thinning and a tendency to dilatation resulting in reduced left ventricular mass. Cardiac function estimated in vivo and in vitro is decreased both under basal conditions and in response to βadrenergic stimulation. Furthermore, flow-induced vasodilatation is impaired in isolated perfused carotid arteries, which express, like the heart, low levels of the protease. These data show that tissue kallikrein is the main kinin-generating enzyme in vivo and that a functional kallikrein-kinin system is necessary for normal cardiac and arterial function in the mouse. They suggest that the kallikrein-kinin system could be involved in the development or progression of cardiovascular diseases.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014EPJST.223.1813G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014EPJST.223.1813G"><span><span class="hlt">Pore</span> dynamics in lipid membranes</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Gozen, I.; Dommersnes, P.</p> <p>2014-09-01</p> <p>Transient circular <span class="hlt">pores</span> can open in plasma membrane of cells due to mechanical stress, and failure to repair such <span class="hlt">pores</span> lead to cell death. Similar <span class="hlt">pores</span> in the form of defects also exist among smectic membranes, such as in myelin sheaths or mitochondrial membranes. The formation and growth of membrane defects are associated with diseases, for example multiple sclerosis. A deeper understanding of membrane <span class="hlt">pore</span> dynamics can provide a more refined picture of membrane integrity-related disease development, and possibly also treatment options and strategies. <span class="hlt">Pore</span> dynamics is also of great importance regarding healthcare applications such as drug delivery, gene or as recently been implied, cancer therapy. The dynamics of <span class="hlt">pores</span> significantly differ in stacks which are confined in 2D compared to those in cells or vesicles. In this short review, we will summarize the dynamics of different types of <span class="hlt">pores</span> that can be observed in biological membranes, which include circular transient, fusion and hemi-fusion <span class="hlt">pores</span>. We will dedicate a section to floral and fractal <span class="hlt">pores</span> which were discovered a few years ago and have highly peculiar characteristics. Finally, we will discuss the repair mechanisms of large area <span class="hlt">pores</span> in conjunction with the current cell membrane repair hypotheses.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2009JHyd..376..337R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2009JHyd..376..337R"><span>The effects of wettability and trapping on relationships between interfacial area, capillary <span class="hlt">pressure</span> and saturation in porous media: A <span class="hlt">pore</span>-scale network modeling approach</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Raeesi, Behrooz; Piri, Mohammad</p> <p>2009-10-01</p> <p>SummaryWe use a three-dimensional mixed-wet random <span class="hlt">pore</span>-scale network model to investigate the impact of wettability and trapping on the relationship between interfacial area, capillary <span class="hlt">pressure</span> and saturation in two-phase drainage and imbibition processes. The model is a three-dimensional network of interconnected <span class="hlt">pores</span> and throats of various geometrical shapes. It allows multiple phases to be present in each capillary element in wetting and spreading layers, as well as occupying the center of the <span class="hlt">pore</span> space. Two different random networks that represent the <span class="hlt">pore</span> space in Berea and a Saudi Arabia reservoir sandstone are used in this study. We allow the wettability of the rock surfaces contacted by oil to alter after primary drainage. The model takes into account both contact angle and trapping hystereses. We model primary oil drainage and water flooding for mixed-wet conditions, and secondary oil injection for a water-wet system. The total interfacial area for <span class="hlt">pores</span> and throats are calculated when the system is at capillary equilibrium. They include contributions from the arc menisci (AMs) between the bulk and corner fluids, and from the main terminal menisci (MTMs) between different bulk fluids. We investigate hysteresis in these relationships by performing water injection into systems of varying wettability and initial water saturation. We show that trapping and contact angle hystereses significantly affect the interfacial area. In a strongly water-wet system, a sharp increase is observed at the beginning of water flood, which shifts the area to a higher level than primary drainage. As we change the wettability of the system from strongly water-wet to strongly oil-wet, the trapped oil saturation decreases significantly. Starting water flood from intermediate water saturations, greater than the irreducible water saturation, can also affect the non-wetting phase entrapment, resulting in different interfacial area behaviors. This can increase the interfacial area</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/26733485','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26733485"><span><span class="hlt">Pore</span> diameter effects on phase behavior of a gas condensate in graphitic one-and two-dimensional nanopores.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Welch, William R W; Piri, Mohammad</p> <p>2016-01-01</p> <p>Molecular dynamics (MD) simulations were performed on a hydrocarbon mixture representing a typical gas condensate composed mostly of methane and other small molecules with small fractions of heavier hydrocarbons, representative of mixtures found in tight shale reservoirs. The fluid was examined both in bulk and confined to graphitic nano-scale slits and <span class="hlt">pores</span>. Numerous widths and diameters of slits and <span class="hlt">pores</span> respectively were examined under variable <span class="hlt">pressures</span> at 300 K in order to find conditions in which the fluid at the center of the apertures would not be affected by capillary condensation due to the oil-wet walls. For the bulk fluid, retrograde phase behavior was verified by liquid volumes obtained from Voronoi tessellations. In cases of both one and two-dimensional confinement, for the smallest apertures, heavy molecules aggregated inside the <span class="hlt">pore</span> space and compression of the gas outside the solid structure lead to decreases in density of the confined fluid. Normal density/<span class="hlt">pressure</span> relationships were observed for slits having gaps of above 3 nm and <span class="hlt">pores</span> having diameters above 6 nm. At 70 bar, the minimum gap width at which the fluid could pass through the center of slits without condensation effects was predicted to be 6 nm and the corresponding diameter in <span class="hlt">pores</span> was predicted to be 8 nm. The models suggest that in nanoscale networks involving <span class="hlt">pores</span> smaller than these limiting dimensions, capillary condensation should significantly impede transmission of natural gases with similar composition.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012JGRB..117.7305T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012JGRB..117.7305T"><span>High fluid <span class="hlt">pressure</span> and triggered earthquakes in the enhanced geothermal system in Basel, Switzerland</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Terakawa, Toshiko; Miller, Stephen A.; Deichmann, Nicholas</p> <p>2012-07-01</p> <p>We analyzed 118 well-constrained focal mechanisms to estimate the <span class="hlt">pore</span> fluid <span class="hlt">pressure</span> field of the stimulated region during the fluid injection experiment in Basel, Switzerland. This technique, termed focal mechanism tomography (FMT), uses the orientations of slip planes within the prevailing regional stress field as an indicator of the fluid <span class="hlt">pressure</span> along the plane at the time of slip. The maximum value and temporal change of excess <span class="hlt">pore</span> fluid <span class="hlt">pressures</span> are consistent with the known history of the wellhead <span class="hlt">pressure</span> applied at the borehole. Elevated <span class="hlt">pore</span> fluid <span class="hlt">pressures</span> were concentrated within 500 m of the open hole section, which are consistent with the spatiotemporal evolution of the induced microseismicity. Our results demonstrate that FMT is a robust approach, being validated at the meso-scale of the Basel stimulation experiment. We found average earthquake triggering excess <span class="hlt">pore</span> fluid <span class="hlt">pressures</span> of about 10 MPa above hydrostatic. Overpressured fluids induced many small events (M < 3) along faults unfavorably oriented relative to the tectonic stress pattern, while the larger events tended to occur along optimally oriented faults. This suggests that small-scale hydraulic networks, developed from the high <span class="hlt">pressure</span> stimulation, interact to load (hydraulically isolated) high strength bridges that produce the larger events. The triggering <span class="hlt">pore</span> fluid <span class="hlt">pressures</span> are substantially higher than that predicted from a linear <span class="hlt">pressure</span> diffusion process from the source boundary, and shows that the system is highly permeable along flow paths that allow fast <span class="hlt">pressure</span> diffusion to the boundaries of the stimulated region.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016AGUFMMR51C2720J','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016AGUFMMR51C2720J"><span>Developing an Effective Model for Shale Gas Flow in Nano-scale <span class="hlt">Pore</span> Clusters based on FIB-SEM Images</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Jiang, W. B.; Lin, M.; Yi, Z. X.; Li, H. S.</p> <p>2016-12-01</p> <p>Nano-scale <span class="hlt">pores</span> existed in the form of clusters are the controlling void space in shale gas reservoir. Gas transport in nanopores which has a significant influence on shale gas' recoverability displays multiple transport regimes, including viscous, slippage flow and Knudsen diffusion. In addition, it is also influenced by <span class="hlt">pore</span> space characteristics. For convenience and efficiency consideration, it is necessary to develop an upscaling model from nano <span class="hlt">pore</span> to <span class="hlt">pore</span> cluster scale. Existing models are more like framework functions that provide a format, because the parameters that represent <span class="hlt">pore</span> space characteristics are underdetermined and may have multiple possibilities. Therefore, it is urgent to make them clear and obtained a model that is closer to reality. FIB-SEM imaging technology is able to acquire three dimensional images with nanometer resolution that nano <span class="hlt">pores</span> can be visible. Based on the images of two shale samples, we used a high-precision <span class="hlt">pore</span> network extraction algorithm to generate equivalent <span class="hlt">pore</span> networks and simulate multiple regime (non-Darcy) flow in it. Several structural parameters can be obtained through <span class="hlt">pore</span> network modelling. It is found that although the throat-radius distributions are very close, throat flux-radius distributions of different samples can be divided into two categories. The variation of tortuosity with <span class="hlt">pressure</span> and the overall trend of throat-flux distribution changes with <span class="hlt">pressure</span> are disclosed. A deeper understanding of shale gas flow in nano-scale <span class="hlt">pore</span> clusters is obtained. After all, an upscaling model that connects absolute permeability, apparent permeability and other characteristic parameters is proposed, and the best parameter scheme considering throat number-radius distribution and flowing porosity for this model is selected out of three schemes based on <span class="hlt">pore</span> scale results, and it can avoid multiple-solution problem and is useful in reservoir modelling and experiment result analysis, etc. This work is supported by</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li class="active"><span>14</span></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_14 --> <div id="page_15" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li class="active"><span>15</span></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="281"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014JSG....69..493Y','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014JSG....69..493Y"><span>Regional <span class="hlt">pore</span>-fluid <span class="hlt">pressures</span> in the active western Taiwan thrust belt: A test of the classic Hubbert-Rubey fault-weakening hypothesis</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Yue, Li-Fan; Suppe, John</p> <p>2014-12-01</p> <p>We document regional <span class="hlt">pore</span>-fluid <span class="hlt">pressures</span> in the active Taiwan thrust belt using 55 deep boreholes to test the classic Hubbert-Rubey hypothesis that high static fluid <span class="hlt">pressures</span> (depth normalized as λ = Pf/ρrgz) account for the extreme weakness of thrust faults, since effective friction μf∗ =μf(1 - λ) . Taiwan fluid <span class="hlt">pressures</span> are dominated by disequilibrium compaction, showing fully compacted sediments with hydrostatic fluid <span class="hlt">pressures</span> at shallow depths until the fluid-retention depth zFRD ≈ 3 km, below which sediments are increasingly undercompacted and overpressured. The Hubbert-Rubey fault weakening coefficient is a simple function of depth (1 - λ) ≈ 0.6zFRD/z. We map present-day and pre-erosion fluid <span class="hlt">pressures</span> and weakening (1 - λ) regionally and show that active thrusts are too shallow relative to zFRD for the classic Hubbert-Rubey mechanism to be important, which requires z ≥ ˜4zFRD ≈ 12 km to have the required order-of-magnitude Hubbert-Rubey fault weakening of (1 - λ) ≤ ˜0.15. The best-characterized thrust is the Chelungpu fault that slipped in the 1999 (Mw = 7.6) Chi-Chi earthquake, which has a low effective friction μf∗ ≈ 0.08- 0.12 , yet lies near the base of the hydrostatic zone at depths of 1-5 km with a modest Hubbert-Rubey weakening of (1 - λ) ≈ 0.4-0.6. Overpressured Miocene and Oligocene detachments at 5-7 km depth have (1 - λ) ≈ 0.3. Therefore, other mechanisms of fault weakening are required, such as the dynamical mechanisms documented for the Chi-Chi earthquake.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017CPL...683..529S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017CPL...683..529S"><span>Density profile of nitrogen in cylindrical <span class="hlt">pores</span> of MCM-41</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Soper, Alan K.; Bowron, Daniel T.</p> <p>2017-09-01</p> <p>A straightforward approach using radiation scattering (X-ray or neutron) combined with atomistic modelling is used to accurately assess the <span class="hlt">pore</span> dimensions in the porous silica, MCM-41. The method is used to calculate the density profile of nitrogen absorbed in this material at a variety of fractional <span class="hlt">pressures</span>, p/p0, where p0 is the saturated vapour <span class="hlt">pressure</span>, up to p/p0 = 0.36 at T = 87 K in the present instance. At this <span class="hlt">pressure</span> two distinct layers of liquid nitrogen occur on the silica surface, with a relatively sharp gas-liquid interface. It is suggested surface tension effects at this interface strongly influence the growth of further layers.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/27494277','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/27494277"><span>Monitoring CO2 invasion processes at the <span class="hlt">pore</span> scale using geological labs on chip.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Morais, S; Liu, N; Diouf, A; Bernard, D; Lecoutre, C; Garrabos, Y; Marre, S</p> <p>2016-09-21</p> <p>In order to investigate at the <span class="hlt">pore</span> scale the mechanisms involved during CO2 injection in a water saturated <span class="hlt">pore</span> network, a series of displacement experiments is reported using high <span class="hlt">pressure</span> micromodels (geological labs on chip - GLoCs) working under real geological conditions (25 < T (°C) < 75 and 4.5 < p (MPa) < 8). The experiments were focused on the influence of three experimental parameters: (i) the p, T conditions, (ii) the injection flow rates and (iii) the <span class="hlt">pore</span> network characteristics. By using on-chip optical characterization and imaging approaches, the CO2 saturation curves as a function of either time or the number of <span class="hlt">pore</span> volume injected were determined. Three main mechanisms were observed during CO2 injection, namely, invasion, percolation and drying, which are discussed in this paper. Interestingly, besides conventional mechanisms, two counterintuitive situations were observed during the invasion and drying processes.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018Fract..2640006L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018Fract..2640006L"><span>Fractal Characteristics of <span class="hlt">Pores</span> in Taiyuan Formation Shale from Hedong Coal Field, China</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Li, Kunjie; Zeng, Fangui; Cai, Jianchao; Sheng, Guanglong; Xia, Peng; Zhang, Kun</p> <p></p> <p>For the purpose of investigating the fractal characteristics of <span class="hlt">pores</span> in Taiyuan formation shale, a series of qualitative and quantitative experiments were conducted on 17 shale samples from well HD-1 in Hedong coal field of North China. The results of geochemical experiments show that Total organic carbon (TOC) varies from 0.67% to 5.32% and the organic matters are in the high mature or over mature stage. The shale samples consist mainly of clay minerals and quartz with minor pyrite and carbonates. The FE-SEM images indicate that three types of <span class="hlt">pores</span>, organic-related <span class="hlt">pores</span>, inorganic-related <span class="hlt">pores</span> and micro-fractures related <span class="hlt">pores</span>, are developed well, and a certain number of intragranular <span class="hlt">pores</span> are found inside quartz and carbonates formed by acid liquid corrosion. The <span class="hlt">pore</span> size distributions (PSDs) broadly range from several to hundreds nanometers, but most <span class="hlt">pores</span> are smaller than 10nm. As the result of different adsorption features at relative <span class="hlt">pressure</span> (0-0.5) and (0.5-1) on the N2 adsorption isotherm, two fractal dimensions D1 and D2 were obtained with the Frenkel-Halsey-Hill (FHH) model. D1 and D2 vary from 2.4227 to 2.6219 and from 2.6049 to 2.7877, respectively. Both TOC and brittle minerals have positive effect on D1 and D2, whereas clay minerals, have a negative influence on them. The fractal dimensions are also influenced by the <span class="hlt">pore</span> structure parameters, such as the specific surface area, BJH <span class="hlt">pore</span> volume, etc. Shale samples with higher D1 could provide more adsorption sites leading to a greater methane adsorption capacity, whereas shale samples with higher D2 have little influence on methane adsorption capacity.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://pubs.er.usgs.gov/publication/70014118','USGSPUBS'); return false;" href="https://pubs.er.usgs.gov/publication/70014118"><span>ROLE OF <span class="hlt">PRESSURE</span> IN SMECTITE DEHYDRATION - EFFECTS ON GEOPRESSURE AND SMECTITE-TO-ILLITE TRANSFORMATION.</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Colten-Bradley, Virginia</p> <p>1987-01-01</p> <p>Evaluation of the effects of <span class="hlt">pressure</span> on the temperature of interlayer water loss (dehydration) by smectites under diagenetic conditions indicates that smectites are stable as hydrated phases in the deep subsurface. Hydraulic and differential <span class="hlt">pressure</span> conditions affect dehydration differently. The temperature of dehydration increase with <span class="hlt">pore</span> fluid <span class="hlt">pressure</span> and interlayer water density. The temperatures of dehydration increase with <span class="hlt">pore</span> fluid <span class="hlt">pressure</span> and interlayer water density. The temperatures of dehydration under differential-presssure conditions are inversely related to <span class="hlt">pressure</span> and interlayer water density. The model presented assumes the effects of <span class="hlt">pore</span> fluid composition and 2:1 layer reactivity to be negligible. Agreement between theoretical and experimental results validate this assumption. Additional aspects of the subject are discussed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011PhDT.......295C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011PhDT.......295C"><span>Functionalized bioinspired microstructured optical fiber <span class="hlt">pores</span> for applications in chemical vapor sensing</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Calkins, Jacob A.</p> <p></p> <p>Chemical vapor sensing for defense, homeland security, environmental, and agricultural application is a challenge, which due combined requirements of ppt sensitivity, high selectivity, and rapid response, cannot be met using conventional analytical chemistry techniques. New sensing approaches and platforms are necessary in order to make progress in this rapidly evolving field. Inspired by the functionalized nanopores on moth sensilla hairs that contribute to the high selectivity and sensitivity of this biological system, a chemical vapor sensor based on the micro to nanoscale <span class="hlt">pores</span> in microstructured optical fibers (MOFs) was designed. This MOF based chemical vapor sensor design utilizes MOF <span class="hlt">pores</span> functionalized with organic self-assembled monolayers (SAMs) for selectivity and separations and a gold plasmonic sensor for detection and discrimination. Thin well-controlled gold films in MOF <span class="hlt">pores</span> are critical components for the fabrication of structured plasmonic chemical vapor sensors. Thermal decomposition of dimethyl Au(II) trifluoroacetylacetonate dissolved in near-critical CO2 was used to deposit gold island films within the MOF <span class="hlt">pores</span>. Using a 3mercatopropyltrimethoxysilane adhesion layer, continuous gold thin films as thin as 20--30 nm were deposited within MOF <span class="hlt">pores</span> as small as 500 nm in diameter. The gold island films proved to be SERS active and were used to detect 900 ppt 2,4 DNT vapor in high <span class="hlt">pressure</span> nitrogen and 6 ppm benzaldehyde. MOF based waveguide Raman (WGR), which can probe the air/silica interface between a waveguiding core and surrounding <span class="hlt">pores</span>, was developed to detect and characterize SAMs and other thin films deposited in micro to nanoscale MOF <span class="hlt">pores</span>. MOF based WGR was used to characterize an octadecyltrichlorosilane (OTS) SAM deposited in 1.6 mum diameter <span class="hlt">pores</span> iv to demonstrate that the SAM was well-formed, uniform along the <span class="hlt">pore</span> length, and only a single layer. MOF based WGR was used to detect a human serum albumin monolayer deposited on the</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017AGUFM.S43B0861H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017AGUFM.S43B0861H"><span>Fluid <span class="hlt">pressure</span> development beneath the décollement at the Nankai subduction zone: its implications for slow earthquakes</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Hirose, T.; Kamiya, N.; Yamamoto, Y.; Heuer, V.; Inagaki, F.; Kubo, Y.</p> <p>2017-12-01</p> <p><span class="hlt">Pore</span> fluid <span class="hlt">pressure</span> along a fault zone is very important for understanding earthquake generation processes in subduction zones. However, quantitative constraints on the <span class="hlt">pore</span> <span class="hlt">pressure</span> are quite limited. Here we report two estimates of the <span class="hlt">pore</span> <span class="hlt">pressure</span> developed within the underthrust sediments in the Nankai Trough off Cape Muroto, Japan, using the shipboard data obtained during IODP Expedition 370 (Heuer et al., 2017). First estimates are based on the depth trend of porosity data in the lower Shikoku Basin (LSB) facies, in which the décollement zone has propagated. Porosities in the LSB facies generally decrease with depth, but turn to increase by 5-7% below the décollement zone at 760 mbsf. Deeper than 830 mbsf, porosities resume a general compaction trend. By applying the method followed by Screaton et al. (2002) in which the downward porosity-increase is reflected by an excess <span class="hlt">pore</span> <span class="hlt">pressure</span>, we estimated the highest excess <span class="hlt">pore</span> <span class="hlt">pressure</span> of 4.2 MPa (λ* = 0.4: a ratio of excess <span class="hlt">pore</span> <span class="hlt">pressure</span> to effective overburden stress) at 1020 mbsf within the underthrust sediments. Another estimate is based on the analysis of upwelling drilling-mud flow from the borehole, which is a direct evidence the development of overpressure. We assumed that the borehole penetrated a disc-shaped high <span class="hlt">pore</span> <span class="hlt">pressure</span> zone with 10 m thickness and the steady-state flow. Then the <span class="hlt">pore</span> <span class="hlt">pressure</span> for a given radius of the disc-shaped zone, which is necessary for explaining the observed flow rate, was calculated using Darcy's law. The calculation yields that the <span class="hlt">pore</span> <span class="hlt">pressure</span> exceeded by 2-4 MPa above hydrostatic in case of the 10-13 m2 permeability and the 100-1000 m radius of the disc-shaped zone. Our analysis indicates a significant development of excess <span class="hlt">pore</span> <span class="hlt">pressure</span> beneath the décollement zone, most likely at the depth of 1020 mbsf where the highest overpressure was estimated from the downhole porosity trend and also an anomaly in relative hydrocarbon gas concentrations. Friction</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016MMTA...47.4217D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016MMTA...47.4217D"><span>Application of a <span class="hlt">Pore</span> Fraction Hot Tearing Model to Directionally Solidified and Direct Chill Cast Aluminum Alloys</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Dou, Ruifeng; Phillion, A. B.</p> <p>2016-08-01</p> <p>Hot tearing susceptibility is commonly assessed using a <span class="hlt">pressure</span> drop equation in the mushy zone that includes the effects of both tensile deformation perpendicular to the thermal gradient as well as shrinkage feeding. In this study, a <span class="hlt">Pore</span> Fraction hot tearing model, recently developed by Monroe and Beckermann (JOM 66:1439-1445, 2014), is extended to additionally include the effect of strain rate parallel to the thermal gradient. The deformation and shrinkage <span class="hlt">pore</span> fractions are obtained on the basis of the dimensionless Niyama criterion and a scaling variable method. First, the model is applied to the binary Al-Cu system under conditions of directional solidification. It is shown that for the same Niyama criterion, a decrease in the cooling rate increases both the deformation and shrinkage <span class="hlt">pore</span> fractions because of an increase in the time spent in the brittle temperature region. Second, the model is applied to the industrial aluminum alloy AA5182 as part of a finite element simulation of the Direct Chill (DC) casting process. It is shown that an increase in the casting speed during DC casting increases the deformation and shrinkage <span class="hlt">pore</span> fractions, causing the maximum point of <span class="hlt">pore</span> fraction to move towards the base of the casting. These results demonstrate that including the strain rate parallel to the thermal gradient significantly improves the predictive quality of hot tearing criteria based on the <span class="hlt">pressure</span> drop equation.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/27132767','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/27132767"><span><span class="hlt">Abnormal</span> stress echocardiography findings in cardiac amyloidosis.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Ong, Kevin C; Askew, J Wells; Dispenzieri, Angela; Maleszewski, Joseph J; Klarich, Kyle W; Anavekar, Nandan S; Mulvagh, Sharon L; Grogan, Martha</p> <p>2016-06-01</p> <p>Cardiac involvement in immunoglobulin light chain (amyloid light chain, AL) amyloidosis is characterized by myocardial interstitial deposition but can also cause obstructive deposits in the coronary microvasculature. We retrospectively identified 20 patients who underwent stress echocardiography within 1 year prior to the histologic diagnosis of AL amyloidosis. Only patients with cardiac amyloidosis and no known obstructive coronary disease were included. Stress echocardiograms (13 exercise; 7 dobutamine) were performed for evaluation of dyspnea and/or chest pain. Stress-induced wall motion <span class="hlt">abnormalities</span> (WMAs) occurred in 11 patients (55%), 4 of whom had normal left ventricular wall thickness. Coronary angiogram was performed in 9 of 11 patients and demonstrated no or mild epicardial coronary artery disease. Seven (54%) patients had an <span class="hlt">abnormal</span> exercise blood <span class="hlt">pressure</span> which occurred with similar likelihood between those with and without stress-induced WMAs. Stress-induced WMAs and <span class="hlt">abnormal</span> exercise blood <span class="hlt">pressure</span> may occur in patients with cardiac AL amyloidosis despite the absence of significant epicardial coronary artery disease. This finding should raise the possibility of cardiac amyloidosis even in the absence of significant myocardial thickening.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012JPS...220..243S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012JPS...220..243S"><span>Active <span class="hlt">pore</span> space utilization in nanoporous carbon-based supercapacitors: Effects of conductivity and <span class="hlt">pore</span> accessibility</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Seredych, Mykola; Koscinski, Mikolaj; Sliwinska-Bartkowiak, Malgorzata; Bandosz, Teresa J.</p> <p>2012-12-01</p> <p>Composites of commercial graphene and nanoporous sodium-salt-polymer-derived carbons were prepared with 5 or 20 weight% graphene. The materials were characterized using the adsorption of nitrogen, SEM/EDX, thermal analysis, Raman spectroscopy and potentiometric titration. The samples' conductivity was also measured. The performance of the carbon composites in energy storage was linked to their porosity and electronic conductivity. The small <span class="hlt">pores</span> (<0.7) were found as very active for double layer capacitance. It was demonstrated that when double layer capacitance is a predominant mechanism of charge storage, the degree of the <span class="hlt">pore</span> space utilization for that storage can be increased by increasing the conductivity of the carbons. That active <span class="hlt">pore</span> space utilization is defined as gravimetric capacitance per unit <span class="hlt">pore</span> volume in <span class="hlt">pores</span> smaller than 0.7 nm. Its magnitude is affected by conductivity of the carbon materials. The functional groups, besides pseudocapacitive contribution, increased the wettability and thus the degree of the <span class="hlt">pore</span> space utilization. Graphene phase, owing to its conductivity, also took part in an insitu increase of the small <span class="hlt">pore</span> accessibility and thus the capacitance of the composites via enhancing an electron transfer to small <span class="hlt">pores</span> and thus imposing the reduction of groups blocking the <span class="hlt">pores</span> for electrolyte ions.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/15261027','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/15261027"><span>A dynamic wicking technique for determining the effective <span class="hlt">pore</span> radius of pregelatinized starch sheets.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Kalogianni, E P; Savopoulos, T; Karapantsios, T D; Raphaelides, S N</p> <p>2004-06-01</p> <p>A dynamic wicking technique is employed for the first time for the determination of the effective mean <span class="hlt">pore</span> radius of a thin-layer porous food: drum dried pregelatinized starch sheets. The technique consists of measuring the penetration rate of various n-alkanes in the porous matrix of the starch sheets and using this data to calculate the effective <span class="hlt">pore</span> radius via the Washburn equation. <span class="hlt">Pore</span> sizes in the order of a few nanometers have been determined in the starch sheets depending on the drum dryer's operating variables (drum rotation speed, steam <span class="hlt">pressure</span> and starch feed concentration). The conditions for the application of the technique in porous foods are discussed as compared to the conditions for single capillaries and inorganic porous material measured in other studies.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017AGUFMMR51A0341Z','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017AGUFMMR51A0341Z"><span>Using Neutron Scattering and Mercury Intrusion Techniques to Characterize Micro- and Nano-<span class="hlt">Pore</span> Structure of Shale</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Zhang, Y.; Barber, T.; Hu, Q.; Bleuel, M.</p> <p>2017-12-01</p> <p>The micro- and nano-<span class="hlt">pore</span> structure of oil shale plays a critical role in hydrocarbon storage and migration. This study aims to characterize the <span class="hlt">pore</span> structure of three Bakken members (i.e., upper organic-rich shale, middle silty/sandy dolomites, and lower organic-rich shale), through small and ultra-small angle neutron scattering (SANS and USANS) techniques, as well as mercury injection capillary <span class="hlt">pressure</span> (MICP) analyses. SANS/USANS have the capabilities of measuring total porosity (connected and closed porosity) across nm-mm spectrum, not measurable than other fluid-invasion approaches, such as MICP which obtains connected porosity and <span class="hlt">pore</span>-throat size distribution. Results from both techniques exhibit different features of upper/lower Bakken and middle Bakken, as a result of various mineral composition and organic matter contents. Middle Bakken is primarily dominated by the mineral <span class="hlt">pores</span>, while in the upper and lower Bakken, organic <span class="hlt">pores</span> contribute a significant portion of total porosity. A combination of USANS/SANS and MICP techniques gives a comprehensive picture of shale micro- and nano-<span class="hlt">pore</span> structure.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017AGUFM.H11G1286W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017AGUFM.H11G1286W"><span><span class="hlt">Pore</span>-scale Modeling of CO2 Local Trapping in Heterogeneous Porous Media with Inter-granular Cements</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Wang, D.; Li, Y.</p> <p>2017-12-01</p> <p>Based on <span class="hlt">pore</span>-scale modeling of CO2/brine multiphase flow in heterogeneous porous media with inter-granular cements, we numerically analyze the effects of cement-modified <span class="hlt">pore</span> structure on CO2 local trapping. Results indicate: 1) small <span class="hlt">pore</span> throat is the main reason for causing CO2 local trapping in front of low-porosity layers (namely dense layers) formed by inter-granular cements; 2) in the case of the same <span class="hlt">pore</span> throat size, the smaller particle size can increase the number of flow paths for CO2 plume and equivalently enhances local permeability, which may counteract the impediment of high capillary <span class="hlt">pressure</span> on CO2 migration to some extent and consequently disables CO2 local capillary trapping; 3) the isolated <span class="hlt">pores</span> by inter-granular cements can lead to dramatic reduction of CO2 saturation inside the dense layers, whereas the change of connectivity of some <span class="hlt">pores</span> due to the cements can increase CO2 accumulation in front of the dense layers by lowering the displacement area of CO2 plume.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016AGUFM.H51B1466K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016AGUFM.H51B1466K"><span>Comparison of <span class="hlt">Pore</span>-Network and Lattice Boltzmann Models for <span class="hlt">Pore</span>-Scale Modeling of Geological Storage of CO2 in Natural Reservoir Rocks</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kohanpur, A. H.; Chen, Y.; Valocchi, A. J.; Tudek, J.; Crandall, D.</p> <p>2016-12-01</p> <p>CO2-brine flow in deep natural rocks is the focus of attention in geological storage of CO2. Understanding rock/flow properties at <span class="hlt">pore</span>-scale is a vital component in field-scale modeling and prediction of fate of injected CO2. There are many challenges in working at the <span class="hlt">pore</span> scale, such as size and selection of representative elementary volume (REV), particularly for material with complex geometry and heterogeneity, and the high computational costs. These issues factor into trade-offs that need to be made in choosing and applying <span class="hlt">pore</span>-scale models. On one hand, <span class="hlt">pore</span>-network modeling (PNM) simplifies the geometry and flow equations but can provide characteristic curves on fairly large samples. On the other hand, the lattice Boltzmann method (LBM) solves Navier-Stokes equations on the real geometry but is limited to small samples due to its high computational costs. Thus, both methods have some advantages but also face some challenges, which warrants a more detailed comparison and evaluation. In this study, we used industrial and micro-CT scans of actual reservoir rock samples to characterize <span class="hlt">pore</span> structure at different resolutions. We ran LBM models directly on the characterized geometry and PNM on the equivalent 3D extracted network to determine single/two-phase flow properties during drainage and imbibition processes. Specifically, connectivity, absolute permeability, relative permeability curve, capillary <span class="hlt">pressure</span> curve, and interface location are compared between models. We also did simulations on several subsamples from different locations including different domain sizes and orientations to encompass analysis of heterogeneity and isotropy. This work is primarily supported as part of the Center for Geologic Storage of CO2, an Energy Frontier Research Center funded by the U.S. Department of Energy, Office of Science and partially supported by the International Institute for Carbon-Neutral Energy Research (WPI-I2CNER) based at Kyushu University, Japan.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/29763930','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/29763930"><span>Rotigotine Improves <span class="hlt">Abnormal</span> Circadian Rhythm of Blood <span class="hlt">Pressure</span> in Parkinson's Disease.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Oka, Hisayoshi; Nakahara, Atuso; Umehara, Tadashi</p> <p>2018-05-15</p> <p>Cardiovascular autonomic failure is commonly associated with Parkinson's disease (PD), affecting the daily lives of patients. Rotigotine was recently reported not to influence cardiovascular autonomic responses in contrast to other dopaminergic drugs. The effect of rotigotine on daily blood <span class="hlt">pressure</span> (BP) fluctuations might reflect autonomic failure in patients with PD. Twenty-five PD patients who were receiving rotigotine and 12 patients not receiving rotigotine were recruited. Systolic BP during the daytime and nighttime was measured by 24-h BP monitoring at an interval of 2 years. The patients were divided into 3 groups according to the BP fluctuation type: dippers (nocturnal fall in BP ≥10%), non-dippers (0-10%), and risers (< 0%). The time course of BP was compared between the patients given rotigotine and those not given rotigotine. Among the 25 patients who received rotigotine, the BP type worsened in 2 patients, was unchanged in 16 patients, and improved in 7 patients. Among the 12 patients who were not receiving rotigotine, the BP type worsened in 5 patients, was unchanged in 4 patients, and improved only in 3 patients (p = 0.042). Rotigotine improves the <span class="hlt">abnormal</span> circadian rhythm of BP in patients with PD. Rotigotine was suggested to have favorable effects on cardiovascular autonomic responses and circadian rhythm in patients with PD. © 2018 S. Karger AG, Basel.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015AGUFM.S13B2823K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AGUFM.S13B2823K"><span>Numerical Models of <span class="hlt">Pore</span> <span class="hlt">Pressure</span> and Stress Changes along Basement Faults due to Wastewater Injection: Applications to Potentially Induced Seismicity in Southern Kansas</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Koltermann, C.; Hearn, E. H.</p> <p>2015-12-01</p> <p>As hydrocarbon extraction techniques that generate large volumes of wastewater have come into widespread use in the central United States, increased volumes have been injected into deep disposal wells, with a corresponding dramatic increase in seismicity rates. South-central Kansas is of particular scientific interest because fluid injection rates have recently increased due to renewed gas and oil production from the Mississippi Lime Play, and the local seismicity is being monitored with a seismometer network deployed by the USGS. In addition, since only a small percentage of injection wells seem to induce seismicity, it is important to characterize contributing factors. We have developed groundwater flow models using MODFLOW-USG to (1) assess hydrogeologic conditions under which seismicity may be triggered, for cases in which wastewater is injected into sedimentary strata overlying fractured crystalline basement rock and to (2) explore the possible relationship between wastewater injection and the November 2014 M 4.8 Milan, Kansas earthquake. The USG version of MODFLOW allows us to use unstructured meshes, which vastly reduces computation time while allowing dense meshing near injection wells and faults. Our single-well test model has been benchmarked to published models (Zhang et al., 2013) and will be used to evaluate sensitivity <span class="hlt">pore</span> <span class="hlt">pressures</span> and stresses to model parameters. Our south Kansas model represents high-rate injection wells, as well as oil and gas wells producing from the Arbuckle and overlying Mississippian formations in a 40-km square region. Based on modeled <span class="hlt">pore</span> <span class="hlt">pressure</span> and stress changes along the target fault, we will identify conditions that would be consistent with inducing an earthquake at the Milan hypocenter. Parameters to be varied include hydraulic properties of sedimentary rock units, crystalline basement and the fault zone, as well as the (poorly resolved) Milan earthquake hypocenter depth.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/28740979','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/28740979"><span>Transport of water molecules through noncylindrical <span class="hlt">pores</span> in multilayer nanoporous graphene.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Shahbabaei, Majid; Kim, Daejoong</p> <p>2017-08-09</p> <p>In this study, molecular dynamics (MD) simulations are used to examine the water transport properties through asymmetric hourglass-shaped <span class="hlt">pores</span> in multilayer nanoporous graphene with a constant interlayer separation of 6 Å. The properties of the tested asymmetric hourglass-shaped <span class="hlt">pores</span> [with the models having long cone (l 1 , -P) and short cone (l 2 , +P) entrances] are compared to a symmetric <span class="hlt">pore</span> model. The study findings indicate that the water occupancy increases across the asymmetric <span class="hlt">pore</span> (l 1 , -P) compared to (l 2 , +P), because of the length effect. The asymmetric <span class="hlt">pore</span>, (l 1 , -P), yields higher flux compared to (l 2 , +P) and even the symmetric model, which can be attributed to the increase in the hydrogen bonds. In addition, the single-file water molecules across the narrowest <span class="hlt">pore</span> diameter inside the (l 2 , +P) <span class="hlt">pore</span> exhibit higher viscosity compared to those in the (l 1 , -P) <span class="hlt">pore</span> because of the increase in the water layering effect. Moreover, it is found that the permeability inside the multilayer hourglass-shaped <span class="hlt">pore</span> depends on the length of the flow path of the water molecules before approaching the layer with the smallest <span class="hlt">pore</span> diameter. The probability of dipole orientation exhibits wider distribution inside the (l 1 , -P) system compared to (l 2 , +P), implying an enhanced formation of hydrogen bonding of water molecules. This results in the fast flow of water molecules. The MD trajectory shows that the dipole orientation across the single-layer graphene has frequently flipped compared to the dipole orientation across the <span class="hlt">pores</span> in multilayer graphene, which is maintained during the whole simulation time (although the dipole orientation has flipped for a few picoseconds at the beginning of the simulation). This can be attributed to the energy barrier induced by the individual layer. The diffusion coefficient of water molecules inside the (l 2 , +P) system increases with <span class="hlt">pressure</span> difference, however, it decreases inside the (l 1 , -P) system because</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/24324038','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/24324038"><span>Office blood <span class="hlt">pressure</span>, ambulatory blood <span class="hlt">pressure</span> monitoring, and echocardiographic <span class="hlt">abnormalities</span> in women with polycystic ovary syndrome: role of obesity and androgen excess.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Luque-Ramírez, Manuel; Martí, David; Fernández-Durán, Elena; Alpañés, Macarena; Álvarez-Blasco, Francisco; Escobar-Morreale, Héctor F</p> <p>2014-03-01</p> <p>Whether or not blood <span class="hlt">pressure</span> (BP) and heart function of women with polycystic ovary syndrome (PCOS) are altered remains unclear, albeit subtle <span class="hlt">abnormalities</span> in the regulation of BP observed in these women might suggest a mild masculinization of their cardiovascular system. To study the influence of obesity and androgen excess on BP and echocardiographic profiles of women with the syndrome, we conducted a cross-sectional case-control study comparing office and ambulatory BP monitoring, as well as echocardiographic assessments, in 63 premenopausal women with the classic phenotype, 33 nonhyperandrogenic women with regular menses, and 25 young men. Forty-nine subjects were lean and 72 had weight excess (body mass index ≥25 kg/m(2)). Participants had no previous history of hypertension and were nonsmokers. Men showed the highest BP readings, and the lowest readings were observed in control women, whereas women with PCOS had intermediate values. Undiagnosed hypertension was more common in subjects with weight excess irrespective of sex and hyperandrogenism. Women with PCOS and weight excess showed frequencies of previously undiagnosed hypertension that were similar to those of men with weight excess and higher than those observed in nonhyperandrogenic women. Lastly, male sex, weight excess and hypertension, the latter in men as well as in women with PCOS, increased left ventricular wall thickness. In summary, our results show that patients with classic PCOS and weight excess frequently have undiagnosed BP <span class="hlt">abnormalities</span>, leading to target organ damage.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/29350744','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/29350744"><span>Preventing Mesh <span class="hlt">Pore</span> Collapse by Designing Mesh <span class="hlt">Pores</span> With Auxetic Geometries: A Comprehensive Evaluation Via Computational Modeling.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Knight, Katrina M; Moalli, Pamela A; Abramowitch, Steven D</p> <p>2018-05-01</p> <p>Pelvic organ prolapse (POP) meshes are exposed to predominately tensile loading conditions in vivo that can lead to <span class="hlt">pore</span> collapse by 70-90%, decreasing overall porosity and providing a plausible mechanism for the contraction/shrinkage of mesh observed following implantation. To prevent <span class="hlt">pore</span> collapse, we proposed to design synthetic meshes with a macrostructure that results in auxetic behavior, the <span class="hlt">pores</span> expand laterally, instead of contracting when loaded. Such behavior can be achieved with a range of auxetic structures/geometries. This study utilized finite element analysis (FEA) to assess the behavior of mesh models with eight auxetic <span class="hlt">pore</span> geometries subjected to uniaxial loading to evaluate their potential to allow for <span class="hlt">pore</span> expansion while simultaneously providing resistance to tensile loading. Overall, substituting auxetic geometries for standard <span class="hlt">pore</span> geometries yielded more <span class="hlt">pore</span> expansion, but often at the expense of increased model elongation, with two of the eight auxetics not able to maintain <span class="hlt">pore</span> expansion at higher levels of tension. Meshes with stable <span class="hlt">pore</span> geometries that remain open with loading will afford the ingrowth of host tissue into the <span class="hlt">pores</span> and improved integration of the mesh. Given the demonstrated ability of auxetic geometries to allow for <span class="hlt">pore</span> size maintenance (and <span class="hlt">pore</span> expansion), auxetically designed meshes have the potential to significantly impact surgical outcomes and decrease the likelihood of major mesh-related complications.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4735595','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4735595"><span>Confinement Correction to Mercury Intrusion Capillary <span class="hlt">Pressure</span> of Shale Nanopores</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Wang, Sen; Javadpour, Farzam; Feng, Qihong</p> <p>2016-01-01</p> <p>We optimized potential parameters in a molecular dynamics model to reproduce the experimental contact angle of a macroscopic mercury droplet on graphite. With the tuned potential, we studied the effects of <span class="hlt">pore</span> size, geometry, and temperature on the wetting of mercury droplets confined in organic-rich shale nanopores. The contact angle of mercury in a circular <span class="hlt">pore</span> increases exponentially as <span class="hlt">pore</span> size decreases. In conjunction with the curvature-dependent surface tension of liquid droplets predicted from a theoretical model, we proposed a technique to correct the common interpretation procedure of mercury intrusion capillary <span class="hlt">pressure</span> (MICP) measurement for nanoporous material such as shale. Considering the variation of contact angle and surface tension with <span class="hlt">pore</span> size improves the agreement between MICP and adsorption-derived <span class="hlt">pore</span> size distribution, especially for <span class="hlt">pores</span> having a radius smaller than 5 nm. The relative error produced in ignoring these effects could be as high as 44%—samples that contain smaller <span class="hlt">pores</span> deviate more. We also explored the impacts of <span class="hlt">pore</span> size and temperature on the surface tension and contact angle of water/vapor and oil/gas systems, by which the capillary <span class="hlt">pressure</span> of water/oil/gas in shale can be obtained from MICP. This information is fundamental to understanding multiphase flow behavior in shale systems. PMID:26832445</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li class="active"><span>15</span></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_15 --> <div id="page_16" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li class="active"><span>16</span></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="301"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19830016300','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19830016300"><span><span class="hlt">Pore</span> size engineering applied to the design of separators for nickel-hydrogen cells and batteries</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Abbey, K. M.; Britton, D. L.</p> <p>1983-01-01</p> <p><span class="hlt">Pore</span> size engineering in starved alkaline multiplate cells involves adopting techniques to widen the volume tolerance of individual cells. Separators with appropriate <span class="hlt">pore</span> size distributions and wettability characteristics (capillary <span class="hlt">pressure</span> considerations) to have wider volume tolerances and an ability to resist dimensional changes in the electrodes were designed. The separators studied for potential use in nickel-hydrogen cells consist of polymeric membranes as well as inorganic microporous mats. In addition to standard measurements, the resistance and distribution of electrolyte as a function of total cell electrolyte content were determined. New composite separators consisting of fibers, particles and/or binders deposited on Zircar cloth were developed in order to engineer the proper capillary <span class="hlt">pressure</span> characteristics in the separator. These asymmetric separators were prepared from a variety of fibers, particles and binders.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/29707814','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/29707814"><span>Antera 3D capabilities for <span class="hlt">pore</span> measurements.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Messaraa, C; Metois, A; Walsh, M; Flynn, J; Doyle, L; Robertson, N; Mansfield, A; O'Connor, C; Mavon, A</p> <p>2018-04-29</p> <p>The cause of enlarged <span class="hlt">pores</span> remains obscure but still remains of concern for women. To complement subjective methods, bioengineered methods are needed for quantification of <span class="hlt">pores</span> visibility following treatments. The study objective was to demonstrate the suitability of <span class="hlt">pore</span> measurements from the Antera 3D. <span class="hlt">Pore</span> measurements were collected on 22 female volunteers aged 18-65 years with the Antera 3D, the DermaTOP and image analysis on photographs. Additionally, 4 raters graded <span class="hlt">pore</span> size on photographs on a scale 0-5. Repeatability of Antera 3D parameters was ascertained and the benefit of a <span class="hlt">pore</span> minimizer product on the cheek was assessed on a sub panel of seven female volunteers. <span class="hlt">Pore</span> parameters using the Antera were shown to depict <span class="hlt">pore</span> severity similar to raters on photographs, except for Max Depth. Mean <span class="hlt">pore</span> volume, mean <span class="hlt">pore</span> area and count were moderately correlated with DermaTOP parameters (up to r = .50). No relationship was seen between the Antera 3D and <span class="hlt">pore</span> visibility analysis on photographs. The most repeatable parameters were found to be mean <span class="hlt">pore</span> volume, mean <span class="hlt">pore</span> area and max depth, especially for the small and medium filters. The benefits of a <span class="hlt">pore</span> minimizer product were the most striking for mean <span class="hlt">pore</span> volume and mean <span class="hlt">pore</span> area when using the small filter for analysis, rather than the medium/large ones. <span class="hlt">Pore</span> measurements with the Antera 3D represent a reliable tool for efficacy and field studies, with an emphasis of the small filter for analysis for the mean <span class="hlt">pore</span> volume/mean <span class="hlt">pore</span> area parameters. © 2018 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/biblio/21004802-hydrodeoxygenation-heavy-oils-derived-from-low-temperature-coal-gasification-over-niw-catalysts-effect-pore-structure','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/21004802-hydrodeoxygenation-heavy-oils-derived-from-low-temperature-coal-gasification-over-niw-catalysts-effect-pore-structure"><span>Hydrodeoxygenation of heavy oils derived from low-temperature coal gasification over NiW catalysts-effect of <span class="hlt">pore</span> structure</span></a></p> <p><a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a></p> <p>Dieter Leckel</p> <p>2008-01-15</p> <p>The effect of the <span class="hlt">pore</span> structure on the hydroprocessing of heavy distillate oils derived from low-temperature coal gasification residues was studied using four NiW catalysts with different <span class="hlt">pore</span> size distributions. The hydroprocessing was conducted at a <span class="hlt">pressure</span> of 17.5 MPa, a temperature range of 370-410{sup o}C, and a 0.50 h{sup -1} space velocity. The degree of hydrodeoxygenation (HDO) in terms of phenolics removal was influenced by the catalyst <span class="hlt">pore</span> structure, with the most preferable peak <span class="hlt">pore</span> diameter for HDO ranging between 6.8 and 16 nm. The catalyst with the highest volume of <span class="hlt">pores</span> in the 3.5-6 nm range showed themore » lowest HDO activity. The apparent activation energies for the HDO reaction varied between 59 and 87 kJ/mol, whereby the lowest values are obtained for the catalysts with a peak <span class="hlt">pore</span> diameter of 11 and 16 nm. 30 refs., 5 figs., 6 tabs.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013AGUFM.T43E2701V','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013AGUFM.T43E2701V"><span>Earthquakes, fluid <span class="hlt">pressures</span> and rapid subduction zone metamorphism</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Viete, D. R.</p> <p>2013-12-01</p> <p>High-<span class="hlt">pressure</span>/low-temperature (HP/LT) metamorphism is commonly incomplete, meaning that large tracts of rock can remain metastable at blueschist- and eclogite-facies conditions for timescales up to millions of years [1]. When HP/LT metamorphism does take place, it can occur over extremely short durations (<<1 Myr) [1-2]. HP/LT metamorphism must be associated with processes that allow large volumes of rock to remain unaffected over long periods of time, but then suddenly undergo localized metamorphism. Existing models for HP/LT metamorphism have focussed on the role of fluids in providing heat for metamorphism [2] or catalyzing metamorphic reactions [1]. Earthquakes in subduction zone settings can occur to depths of 100s of km. Metamorphic dehydration and the associated development of elevated <span class="hlt">pore</span> <span class="hlt">pressures</span> in HP/LT metamorphic rocks has been identified as a cause of earthquake activity at such great depths [3-4]. The process of fracturing/faulting significantly increases rock permeability, causing channelized fluid flow and dissipation of <span class="hlt">pore</span> <span class="hlt">pressures</span> [3-4]. Thus, deep subduction zone earthquakes are thought to reflect an evolution in fluid <span class="hlt">pressure</span>, involving: (1) an initial increase in <span class="hlt">pore</span> <span class="hlt">pressure</span> by heating-related dehydration of subduction zone rocks, and (2) rapid relief of <span class="hlt">pore</span> <span class="hlt">pressures</span> by faulting and channelized flow. Models for earthquakes at depth in subduction zones have focussed on the in situ effects of dehydration and then sudden escape of fluids from the rock mass following fracturing [3-4]. On the other hand, existing models for rapid and incomplete metamorphism in subduction zones have focussed only on the effects of heating and/or hydration with the arrival of external fluids [1-2]. Significant changes in <span class="hlt">pressure</span> over very short timescales should result in rapid mineral growth and/or disequilibrium texture development in response to overstepping of mineral reaction boundaries. The repeated process of dehydration-<span class="hlt">pore</span> <span class="hlt">pressure</span> development-earthquake-<span class="hlt">pore</span></p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/servlets/purl/10174572','SCIGOV-STC'); return false;" href="https://www.osti.gov/servlets/purl/10174572"><span>A <span class="hlt">pore</span>-level scenario for the development of mixed-wettability in oil reservoirs</span></a></p> <p><a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a></p> <p>Kovscek, A.R.; Wong, H.; Radke, C.J.</p> <p></p> <p>Understanding the role of thin films in porous media is vital if wettability is to be elucidated at the <span class="hlt">pore</span> level. The type and thickness of films coating <span class="hlt">pore</span> walls determines reservoir wettability and whether or not reservoir rock can be altered from its initial state of wettability. <span class="hlt">Pore</span> shape, especially <span class="hlt">pore</span> wall curvature, is an important factor in determining wetting-film thicknesses. Yet, <span class="hlt">pore</span> shape and the physics of thin wetting films are generally neglected in models of flow in porous rocks. This paper incorporates thin-film forces into a collection of star-shaped capillary tubes model to describe the geological developmentmore » of mixed-wettability in reservoir rock. Here, mixed-wettability refers to continuous and distinct oil and water-wetting surfaces coexisting in the porous medium. The proposed model emphasizes the remarkable role of thin films. New <span class="hlt">pore</span>-level fluid configurations arise that are quite unexpected. For example, efficient water displacement of oil (i.e, low residual oil saturation) characteristic of mixed-wettability porous media is ascribed to interconnected oil lenses or rivulets which bridge the walls adjacent to a <span class="hlt">pore</span> corner. Predicted residual oil saturations are approximately 35 % less in mixed-wet rock compared to completely water-wet rock. Calculated capillary <span class="hlt">pressure</span> curves mimic those of mixed-wet porous media in the primary drainage of water, imbibition of water, and secondary drainage modes. Amott-Harvey indices range from {minus}0.18 to 0.36 also in good agreement with experimental values. (Morrow et al, 1986; Judhunandan and Morrow, 1991).« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018Fract..2640013W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018Fract..2640013W"><span>Morphology and Fractal Characterization of Multiscale <span class="hlt">Pore</span> Structures for Organic-Rich Lacustrine Shale Reservoirs</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Wang, Yang; Wu, Caifang; Zhu, Yanming; Chen, Shangbin; Liu, Shimin; Zhang, Rui</p> <p></p> <p>Lacustrine shale gas has received considerable attention and has been playing an important role in unconventional natural gas production in China. In this study, multiple techniques, including total organic carbon (TOC) analysis, X-ray diffraction (XRD) analysis, field emission scanning electron microscopy (FE-SEM), helium pycnometry and low-<span class="hlt">pressure</span> N2 adsorption have been applied to characterize the <span class="hlt">pore</span> structure of lacustrine shale of Upper Triassic Yanchang Formation from the Ordos Basin. The results show that organic matter (OM) <span class="hlt">pores</span> are the most important type dominating the <span class="hlt">pore</span> system, while interparticle (interP) <span class="hlt">pores</span>, intraparticle (intraP) and microfractures are also usually observed between or within different minerals. The shapes of OM <span class="hlt">pores</span> are less complex compared with the other two <span class="hlt">pore</span> types based on the Image-Pro Plus software analysis. In addition, the specific surface area ranges from 2.76m2/g to 10.26m2/g and the <span class="hlt">pore</span> volume varies between 0.52m3/100g and 1.31m3/100g. Two fractal dimensions D1 and D2 were calculated using Frenkel-Halsey-Hill (FHH) method, with D1 varying between 2.510 and 2.632, and D2 varying between 2.617 and 2.814. Further investigation indicates that the fractal dimensions exhibit positive correlations with TOC contents, whereas there is no definite relationship observed between fractal dimensions and clay minerals. Meanwhile, the fractal dimensions increase with the increase in specific surface area, and is negatively correlated with the <span class="hlt">pore</span> size.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018PhRvE..97f2406B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018PhRvE..97f2406B"><span>Enhanced polymer capture speed and extended translocation time in <span class="hlt">pressure</span>-solvation traps</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Buyukdagli, Sahin</p> <p>2018-06-01</p> <p>The efficiency of nanopore-based biosequencing techniques requires fast anionic polymer capture by like-charged <span class="hlt">pores</span> followed by a prolonged translocation process. We show that this condition can be achieved by setting a <span class="hlt">pressure</span>-solvation trap. Polyvalent cation addition to the KCl solution triggers the like-charge polymer-<span class="hlt">pore</span> attraction. The attraction speeds-up the <span class="hlt">pressure</span>-driven polymer capture but also traps the molecule at the <span class="hlt">pore</span> exit, reducing the polymer capture time and extending the polymer escape time by several orders of magnitude. By direct comparison with translocation experiments [D. P. Hoogerheide et al., ACS Nano 8, 7384 (2014), 10.1021/nn5025829], we characterize as well the electrohydrodynamics of polymers transport in <span class="hlt">pressure</span>-voltage traps. We derive scaling laws that can accurately reproduce the <span class="hlt">pressure</span> dependence of the experimentally measured polymer translocation velocity and time. We also find that during polymer capture, the electrostatic barrier on the translocating molecule slows down the liquid flow. This prediction identifies the streaming current measurement as a potential way to probe electrostatic polymer-<span class="hlt">pore</span> interactions.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/29606354','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/29606354"><span>Visualization of Membrane <span class="hlt">Pore</span> in Live Cells Reveals a Dynamic-<span class="hlt">Pore</span> Theory Governing Fusion and Endocytosis.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Shin, Wonchul; Ge, Lihao; Arpino, Gianvito; Villarreal, Seth A; Hamid, Edaeni; Liu, Huisheng; Zhao, Wei-Dong; Wen, Peter J; Chiang, Hsueh-Cheng; Wu, Ling-Gang</p> <p>2018-05-03</p> <p>Fusion is thought to open a <span class="hlt">pore</span> to release vesicular cargoes vital for many biological processes, including exocytosis, intracellular trafficking, fertilization, and viral entry. However, fusion <span class="hlt">pores</span> have not been observed and thus proved in live cells. Its regulatory mechanisms and functions remain poorly understood. With super-resolution STED microscopy, we observed dynamic fusion <span class="hlt">pore</span> behaviors in live (neuroendocrine) cells, including opening, expansion, constriction, and closure, where <span class="hlt">pore</span> size may vary between 0 and 490 nm within 26 milliseconds to seconds (vesicle size: 180-720 nm). These <span class="hlt">pore</span> dynamics crucially determine the efficiency of vesicular cargo release and vesicle retrieval. They are generated by competition between <span class="hlt">pore</span> expansion and constriction. Pharmacology and mutation experiments suggest that expansion and constriction are mediated by F-actin-dependent membrane tension and calcium/dynamin, respectively. These findings provide the missing live-cell evidence, proving the fusion-<span class="hlt">pore</span> hypothesis, and establish a live-cell dynamic-<span class="hlt">pore</span> theory accounting for fusion, fission, and their regulation. Published by Elsevier Inc.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/23261298','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/23261298"><span>Estimation of methacrylate monolith binding capacity from <span class="hlt">pressure</span> drop data.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Podgornik, Aleš; Smrekar, Vida; Krajnc, Peter; Strancar, Aleš</p> <p>2013-01-11</p> <p>Convective chromatographic media comprising of membranes and monoliths represent an important group of chromatographic supports due to their flow-unaffected chromatographic properties and consequently fast separation and purification even of large biological macromolecules. Consisting of a single piece of material, common characterization procedures based on analysis of a small sample assuming to be representative for the entire batch, cannot be applied. Because of that, non-invasive characterization methods are preferred. In this work <span class="hlt">pressure</span> drop was investigated for an estimation of dynamic binding capacity (DBC) of proteins and plasmid DNA for monoliths with different <span class="hlt">pore</span> sizes. It was demonstrated that methacrylate monolith surface area is reciprocally proportional to <span class="hlt">pore</span> diameter and that <span class="hlt">pressure</span> drop on monolith is reciprocally proportional to square <span class="hlt">pore</span> size demonstrating that methacrylate monolith microstructure is preserved by changing <span class="hlt">pore</span> size. Based on these facts mathematical formalism has been derived predicting that DBC is in linear correlation with the square root of <span class="hlt">pressure</span> drop. This was experimentally confirmed for ion-exchange and hydrophobic interactions for proteins and plasmid DNA. Furthermore, <span class="hlt">pressure</span> drop was also applied for an estimation of DBC in grafted layers of different thicknesses as estimated from the <span class="hlt">pressure</span> drop data. It was demonstrated that the capacity is proportional to the estimated grafted layer thickness. Copyright © 2012 Elsevier B.V. All rights reserved.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018E%26ES..118a2067N','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018E%26ES..118a2067N"><span>Laboratory characterization of shale <span class="hlt">pores</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Nur Listiyowati, Lina</p> <p>2018-02-01</p> <p>To estimate the potential of shale gas reservoir, one needs to understand the characteristics of <span class="hlt">pore</span> structures. Characterization of shale gas reservoir microstructure is still a challenge due to ultra-fine grained micro-fabric and micro level heterogeneity of these sedimentary rocks. The sample used in the analysis is a small portion of any reservoir. Thus, each measurement technique has a different result. It raises the question which methods are suitable for characterizing <span class="hlt">pore</span> shale. The goal of this paper is to summarize some of the microstructure analysis tools of shale rock to get near-real results. The two analyzing <span class="hlt">pore</span> structure methods are indirect measurement (MIP, He, NMR, LTNA) and direct observation (SEM, TEM, Xray CT). Shale rocks have a high heterogeneity; thus, it needs multiscale quantification techniques to understand their <span class="hlt">pore</span> structures. To describe the complex <span class="hlt">pore</span> system of shale, several measurement techniques are needed to characterize the surface area and <span class="hlt">pore</span> size distribution (LTNA, MIP), shapes, size and distribution of <span class="hlt">pore</span> (FIB-SEM, TEM, Xray CT), and total porosity (He pycnometer, NMR). The choice of techniques and methods should take into account the purpose of the analysis and also the time and budget.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/biblio/22408142-cathode-fall-thickness-abnormal-glow-discharges-between-parallel-plane-electrodes-different-radii-low-pressure','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/22408142-cathode-fall-thickness-abnormal-glow-discharges-between-parallel-plane-electrodes-different-radii-low-pressure"><span>Cathode fall thickness of <span class="hlt">abnormal</span> glow discharges between parallel-plane electrodes in different radii at low <span class="hlt">pressure</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a></p> <p>Fu, Yangyang; Luo, Haiyun; Zou, Xiaobing</p> <p>2015-02-15</p> <p>In order to investigate the influence of electrode radius on the characteristics of cathode fall thickness, experiments of low-<span class="hlt">pressure</span> (20 Pa ≤ p ≤ 30 Pa) <span class="hlt">abnormal</span> glow discharge were carried out between parallel-plane electrodes in different radii keeping gap distance unchanged. Axial distributions of light intensity were obtained from the discharge images captured using a Charge Coupled Device camera. The assumption that the position of the negative glow peak coincides with the edge of cathode fall layer was verified based on a two-dimensional model, and the cathode fall thicknesses, d{sub c}, were calculated from the axial distributions of light intensity. It was observedmore » that the position of peak emission shifts closer to the cathode as current or <span class="hlt">pressure</span> grows. The dependence of cathode fall thickness on the gas <span class="hlt">pressure</span> and normalized current J/p{sup 2} was presented, and it was found that for discharges between electrodes in large radius the curves of pd{sub c} against J/p{sup 2} were superimposed on each other, however, this phenomenon will not hold for discharges between the smaller electrodes. The reason for this phenomenon is that the transverse diffusions of charged particles are not the same in two gaps between electrodes with different radii.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018JGRB..123..311T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018JGRB..123..311T"><span>Modeling Thermal <span class="hlt">Pressurization</span> Around Shallow Dikes Using Temperature-Dependent Hydraulic Properties: Implications for Deformation Around Intrusions</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Townsend, Meredith R.</p> <p>2018-01-01</p> <p><span class="hlt">Pressurization</span> and flow of groundwater around igneous intrusions depend in part on the hydraulic diffusivity of the host rocks and processes that enhance diffusivity, such as fracturing, or decrease diffusivity, such as mineral precipitation during chemical alteration. Characterizing and quantifying the coupled effects of alteration, <span class="hlt">pore</span> <span class="hlt">pressurization</span>, and deformation have significant implications for deformation around intrusions, geothermal energy, contact metamorphism, and heat transfer at mid-ocean ridges. Fractures around dikes at Ship Rock, New Mexico, indicate that <span class="hlt">pore</span> <span class="hlt">pressures</span> in the host rocks exceeded hydrostatic conditions by at least 15 MPa following dike emplacement. Hydraulic measurements and petrographic analysis indicate that mineral precipitation clogged the <span class="hlt">pores</span> of the host rock, reducing porosity from 0.25 to <0.10 and reducing permeability by 5 orders of magnitude. Field data from Ship Rock are used to motivate and constrain numerical models for thermal <span class="hlt">pore</span> fluid <span class="hlt">pressurization</span> adjacent to a meter-scale dike, using temperature-dependent hydraulic properties in the host rock as a proxy for porosity loss by mineral precipitation during chemical alteration. Reduction in permeability by chemical alteration has a negligible effect on <span class="hlt">pressurization</span>. However, reduction in porosity by mineral precipitation increases fluid <span class="hlt">pressure</span> by constricting <span class="hlt">pore</span> volume and is identified as a potentially significant source of <span class="hlt">pressure</span>. A scaling relationship is derived to determine when porosity loss becomes important; if permeability is low enough, <span class="hlt">pressurization</span> by porosity loss outweighs <span class="hlt">pressurization</span> by thermal expansion of fluids.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4600974','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4600974"><span>The development of <span class="hlt">pressure</span> across membranes in Donnan systems</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Ilani, Asher</p> <p>2015-01-01</p> <p>The <span class="hlt">pressure</span> that develops between the two sides of a Donnan system is equal to the difference between the osmotic values of the two solutions, even though permeant ions may constitute a significant part of that difference. This is amply documented for the case of membranes that allow water movement through them by single molecules diffusing in isolation or in series through specific proteins (such as aquaporins). In this article, the development of <span class="hlt">pressure</span> was analysed for a system in which membranes contain a few bulk aqueous <span class="hlt">pores</span> that prevent charged polymers from entering them due to their size. It is shown analytically that the <span class="hlt">pressure</span> that develops by the action of the electric field on the net charges in the <span class="hlt">pores</span> is equal to the difference in the osmotic values of the solutions contributed by the permeant ions. Thus, the sum of the <span class="hlt">pressures</span> that develop in the system due to the action of the electric field in the <span class="hlt">pores</span> (a pushing force) and the concentration of the impermeant polymers at the interface (a sucking force), accounts for the total colloid osmotic <span class="hlt">pressure</span> in these systems. PMID:26456154</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017JHyd..550..331Z','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017JHyd..550..331Z"><span>CO2 breakthrough <span class="hlt">pressure</span> and permeability for unsaturated low-permeability sandstone of the Ordos Basin</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Zhao, Yan; Yu, Qingchun</p> <p>2017-07-01</p> <p>With rising threats from greenhouse gases, capture and injection of CO2 into suitable underground formations is being considered as a method to reduce anthropogenic emissions of CO2 to the atmosphere. As the injected CO2 will remain in storage for hundreds of years, the safety of CO2 geologic sequestration is a major concern. The low-permeability sandstone of the Ordos Basin in China is regarded as both caprock and reservoir rock, so understanding the breakthrough <span class="hlt">pressure</span> and permeability of the rock is necessary. Because part of the <span class="hlt">pore</span> volume experiences a non-wetting phase during the CO2 injection and migration process, the rock may be in an unsaturated condition. And if accidental leakage occurs, CO2 will migrate up into the unsaturated zone. In this study, breakthrough experiments were performed at various degrees of water saturation with five core samples of low-permeability sandstone obtained from the Ordos Basin. The experiments were conducted at 40 °C and <span class="hlt">pressures</span> of >8 MPa to simulate the geological conditions for CO2 sequestration. The results indicate that the degree of water saturation and the <span class="hlt">pore</span> structure are the main factors affecting the rock breakthrough <span class="hlt">pressure</span> and permeability, since the influence of calcite dissolution and clay mineral swelling during the saturation process is excluded. Increasing the average <span class="hlt">pore</span> radius or most probable <span class="hlt">pore</span> radius leads to a reduction in the breakthrough <span class="hlt">pressure</span> and an increase by several orders of magnitude in scCO2 effective permeability. In addition, the breakthrough <span class="hlt">pressure</span> rises and the scCO2 effective permeability decreases when the water saturation increases. However, when the average <span class="hlt">pore</span> radius is greater than 0.151 μm, the degree of water saturation will has a little effect on the breakthrough <span class="hlt">pressure</span>. On this foundation, if the most probable <span class="hlt">pore</span> radius of the core sample reaches 1.760 μm, the breakthrough <span class="hlt">pressure</span> will not be impacted by the increasing water saturation. We establish</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.heart.org/HEARTORG/Conditions/HighBloodPressure/AboutHighBloodPressure/Low-Blood-Pressure_UCM_301785_Article.jsp','NIH-MEDLINEPLUS'); return false;" href="http://www.heart.org/HEARTORG/Conditions/HighBloodPressure/AboutHighBloodPressure/Low-Blood-Pressure_UCM_301785_Article.jsp"><span>Low Blood <span class="hlt">Pressure</span></span></a></p> <p><a target="_blank" href="http://medlineplus.gov/">MedlinePlus</a></p> <p></p> <p></p> <p>... to low blood <span class="hlt">pressure</span> are an <span class="hlt">abnormally</span> low heart rate ( bradycardia ), problems with heart valves , heart attack and ... occurred. Is low blood <span class="hlt">pressure</span> related to low heart rate? Find out . This content was last reviewed October ...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017APS..DFDD14007F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017APS..DFDD14007F"><span>Water imbibition by mica <span class="hlt">pores</span>: what happens when capillary flow is suppressed?</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Fang, Chao; Qiao, Rui</p> <p>2017-11-01</p> <p>The imbibition of liquids into porous media plays a critical role in numerous applications. Most prior studies focused on imbibition driven by capillary flows. In this work, we study the imbibition of water into slit-shaped mica <span class="hlt">pores</span> filled with <span class="hlt">pressurized</span> methane using molecular simulations. Despite that capillary flow is suppressed by the high gas <span class="hlt">pressure</span>, water is imbibed into the <span class="hlt">pore</span> as monolayer liquid films. Since the classical hydrodynamic flow is not readily applicable for the monolayer water film propagating on the mica wall and the imbibition is driven by the strong affinity of water molecules to the mica walls, the observed imbibition is best taken as surface hydration. We show that the dynamics of water's imbibition front follows a simple diffusive scaling law. The effective diffusion coefficient of the imbibition front, however, is more than ten times larger than the diffusion coefficient of the water molecules in the water film adsorbed on the mica walls. Using a molecular theory originally developed for the spreading of monolayer films on solid substrates, we clarify the mechanism underlying the rapid water imbibition observed here.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19840047400&hterms=applied+engineering&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3Dapplied%2Bengineering','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19840047400&hterms=applied+engineering&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3Dapplied%2Bengineering"><span><span class="hlt">Pore</span> size engineering applied to the design of separators for nickel-hydrogen cells and batteries</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Abbey, K. M.; Britton, D. L.</p> <p>1983-01-01</p> <p><span class="hlt">Pore</span> size engineering in starved alkaline multiplate cells involves adopting techniques to widen the volume tolerance of individual cells. Separators with appropriate <span class="hlt">pore</span> size distributions and wettability characteristics (capillary <span class="hlt">pressure</span> considerations) to have wider volume tolerances and an ability to resist dimensional changes in the electrodes were designed. The separators studied for potential use in nickel-hydrogen cells consist of polymeric membranes as well as inorganic microporous mats. In addition to standard measurements, the resistance and distribution of electrolyte as a function of total cell electrolyte content were determined. New composite separators consisting of fibers, particles and/or binders deposited on Zircar cloth were developed in order to engineer the proper capillary <span class="hlt">pressure</span> characteristics in the separator. These asymmetric separators were prepared from a variety of fibers, particles and binders. Previously announced in STAR as N83-24571</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/21084772','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/21084772"><span>Fabrication, properties, and applications of porous metals with directional <span class="hlt">pores</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Nakajima, Hideo</p> <p>2010-01-01</p> <p>Lotus-type porous metals with aligned long cylindrical <span class="hlt">pores</span> are fabricated by unidirectional solidification from the melt with a dissolved gas such as hydrogen, nitrogen, or oxygen. The gas atoms can be dissolved into the melt via a <span class="hlt">pressurized</span> gas atmosphere or thermal decomposition of gaseous compounds. Three types of solidification techniques have been developed: mold casting, continuous zone melting, and continuous casting techniques. The last method is superior from the viewpoint of mass production of lotus metals. The observed anisotropic behaviors of the mechanical properties, sound absorption, and thermal conductivity are inherent to the anisotropic porous structure. In particular, the remarkable anisotropy in the mechanical strength is attributed to the stress concentration around the <span class="hlt">pores</span> aligned perpendicular to the loading direction. Heat sinks are a promising application of lotus metals due to the high cooling performance with a large heat transfer.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2003AGUFM.T41A..04T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2003AGUFM.T41A..04T"><span>Fluid <span class="hlt">Pressure</span> in the Shallow Plate Interface at the Nankai Trough Subduction Zone</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Tobin, H. J.; Saffer, D.</p> <p>2003-12-01</p> <p>The factors controlling the occurrence, magnitude, and other characteristics of great earthquakes is a fundamental outstanding question in fault physics. <span class="hlt">Pore</span> fluid <span class="hlt">pressure</span> is perhaps the most critical yet poorly known parameter governing the strength and seismogenic character of plate boundary faults, but unfortunately cannot be directly inferred through available geophysical sensing methods. Moreover, true in situ fluid <span class="hlt">pressure</span> has proven difficult to measure even in boreholes. At the Nankai Trough, several hundred meters of sediment are subducted beneath the frontal portion of the accretionary prism. The up-dip portion of the plate interface is therefore hosted in these fine-grained marine sedimentary rocks. ODP Leg 190 and 196 showed that these rapidly-loaded underthrust sediments are significantly overpressured near the deformation front. Here, we attempt to quantitatively infer porosity, <span class="hlt">pore</span> <span class="hlt">pressure</span>, and effective normal stress at the plate interface at depths currently inaccessible to drilling. Using seismic reflection interval velocity calibrated at the boreholes to porosity, we quantitatively infer <span class="hlt">pore</span> <span class="hlt">pressure</span> to ˜ 20 km down-dip of the deformation front, to a plate interface depth of ˜ 6 km. We have developed a Nankai-specific velocity-porosity transform using ODP cores and logs. We use this function to derive a porosity profile for each of two down-dip seismic sections extracted from a 3-D dataset from the Cape Muroto region. We then calculate <span class="hlt">pore</span> fluid <span class="hlt">pressure</span> and effective vertical (fault-normal) stress for the underthrust sediment section using a compaction disequilibrium approach and core-based consolidation test data. Because the <span class="hlt">pore</span> fluid <span class="hlt">pressure</span> at the fault interface is likely controlled by that of the top of the underthrust section, this calculation represents a quantitative profile of effective stress and <span class="hlt">pore</span> <span class="hlt">pressure</span> at the plate interface. Results show that seismic velocity and porosity increase systematically downdip in the</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/14607477','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/14607477"><span>Effects of <span class="hlt">pore</span> volume-transmissivity correlation on transport phenomena.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Lunati, Ivan; Kinzelbach, Wolfgang; Sørensen, Ivan</p> <p>2003-12-01</p> <p>The relevant velocity that describes transport phenomena in a porous medium is the <span class="hlt">pore</span> velocity. For this reason, one needs not only to describe the variability of transmissivity, which fully determines the Darcy velocity field for given source terms and boundary conditions, but also any variability of the <span class="hlt">pore</span> volume. We demonstrate that hydraulically equivalent media with exactly the same transmissivity field can produce dramatic differences in the displacement of a solute if they have different <span class="hlt">pore</span> volume distributions. In particular, we demonstrate that correlation between <span class="hlt">pore</span> volume and transmissivity leads to a much smoother and more homogeneous solute distribution. This was observed in a laboratory experiment performed in artificial fractures made of two plexiglass plates into which a space-dependent aperture distribution was milled. Using visualization by a light transmission technique, we observe that the solute behaviour is much smoother and more regular after the fractures are filled with glass powder, which plays the role of a homogeneous fault gouge material. This is due to a perfect correlation between <span class="hlt">pore</span> volume and transmissivity that causes <span class="hlt">pore</span> velocity to be not directly dependent on the transmissivity, but only indirectly through the hydraulic gradient, which is a much smoother function due to the diffusive behaviour of the flow equation acting as a filter. This smoothing property of the <span class="hlt">pore</span> volume-transmissivity correlation is also supported by numerical simulations of tracer tests in a dipole flow field. Three different conceptual models are used: an empty fracture, a rough-walled fracture filled with a homogeneous material and a parallel-plate fracture with a heterogeneous fault gouge. All three models are hydraulically equivalent, yet they have a different <span class="hlt">pore</span> volume distribution. Even if piezometric heads and specific flow rates are exactly the same at any point of the domain, the transport process differs dramatically. These</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li class="active"><span>16</span></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_16 --> <div id="page_17" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li class="active"><span>17</span></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="321"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015EGUGA..17.1528P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015EGUGA..17.1528P"><span><span class="hlt">Pore</span> space connectivity and porosity using CT scans of tropical soils</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Previatello da Silva, Livia; de Jong Van Lier, Quirijn</p> <p>2015-04-01</p> <p>Microtomography has been used in soil physics for characterization and allows non-destructive analysis with high-resolution, yielding a three-dimensional representation of <span class="hlt">pore</span> space and fluid distribution. It also allows quantitative characterization of <span class="hlt">pore</span> space, including <span class="hlt">pore</span> size distribution, shape, connectivity, porosity, tortuosity, orientation, preferential pathways and is also possible predict the saturated hydraulic conductivity using Darcy's equation and a modified Poiseuille's equation. Connectivity of <span class="hlt">pore</span> space is an important topological property of soil. Together with porosity and <span class="hlt">pore</span>-size distribution, it governs transport of water, solutes and gases. In order to quantify and analyze <span class="hlt">pore</span> space (quantifying connectivity of <span class="hlt">pores</span> and porosity) of four tropical soils from Brazil with different texture and land use, undisturbed samples were collected in São Paulo State, Brazil, with PVC ring with 7.5 cm in height and diameter of 7.5 cm, depth of 10 - 30 cm from soil surface. Image acquisition was performed with a CT system Nikon XT H 225, with technical specifications of dual reflection-transmission target system including a 225 kV, 225 W high performance Xray source equipped with a reflection target with pot size of 3 μm combined with a nano-focus transmission module with a spot size of 1 μm. The images were acquired at specific energy level for each soil type, according to soil texture, and external copper filters were used in order to allow the attenuation of low frequency X-ray photons and passage of one monoenergetic beam. This step was performed aiming minimize artifacts such as beam hardening that may occur during the attenuation in the material interface with different densities within the same sample. Images were processed and analyzed using ImageJ/Fiji software. Retention curve (tension table and the <span class="hlt">pressure</span> chamber methods), saturated hydraulic conductivity (constant head permeameter), granulometry, soil density and particle density</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016AGUFMMR41A2693K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016AGUFMMR41A2693K"><span>The effect of the <span class="hlt">pore</span>-fluid factor on strength and failure mechanism of Wilkeson sandstone</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kätker, A. K.; Rempe, M.; Renner, J.</p> <p>2016-12-01</p> <p>The effective stress law, σn,eff = σn - αpf, is a central tool in analysing phenomena related to hydromechanical coupling, such as fluid-induced seismicity or aftershock activity. The effective-stress coefficient α assumes different values for specific physical properties and may deviate from 1. The limited number of studies suggest that brittle compressive strength obeys an effective-stress law when effective drainage is achieved. Yet, open questions remain regarding, e.g., the role of the loading path. We performed suites of triaxial compression tests on samples of Wilkeson sandstone at a range of <span class="hlt">pore</span>-fluid <span class="hlt">pressures</span> but identical effective confining <span class="hlt">pressure</span> (60, 100, and 120 MPa) maintaining the <span class="hlt">pore</span>-fluid factor λ = pf / pc constant (0.05, 0.2, 0.4, 0.55) during the isostatic loading stage to ensure uniform loading paths. Samples were shortened with a strain rate of 4×10-7 s-1 yielding drained conditions. All tests were terminated at a total axial strain of 4.5% for comparability of microstructures. The tests also included continuous permeability determination and ultrasonic p-wave-velocity measurements to monitor microstructural evolution. Results from experiments conducted at peff = 100 MPa show that dry samples exhibit a higher peak strength and brittle failure while water-saturated samples tend to deform at lower stress by cataclastic flow indicating physico-chemical weakening. Regardless of <span class="hlt">pore</span>-fluid factor, the saturated experiments exhibit similar peak and residual strength. Differences in failure mechanism (degree of macroscopic localization) and volumetric strain evolution are however noticed, albeit without systematic relation to <span class="hlt">pore</span>-fluid factor. Microstructure analyses by optical and scanning electron microscopy revealed an evolution from localized shear zones in dry experiments and experiments with a low <span class="hlt">pore</span>-fluid factor to rather distributed cataclastic flow for experiments with high <span class="hlt">pore</span> fluid factors. Yet, mechanical and structural</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://pubs.er.usgs.gov/publication/70023892','USGSPUBS'); return false;" href="https://pubs.er.usgs.gov/publication/70023892"><span>A fault constitutive relation accounting for thermal <span class="hlt">pressurization</span> of <span class="hlt">pore</span> fluid</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Andrews, D.J.</p> <p>2002-01-01</p> <p>The heat generated in a slip zone during an earthquake can raise fluid <span class="hlt">pressure</span> and thereby reduce frictional resistance to slip. The amount of fluid <span class="hlt">pressure</span> rise depends on the associated fluid flow. The heat generated at a given time produces fluid <span class="hlt">pressure</span> that decreases inversely with the square root of hydraulic diffusivity times the elapsed time. If the slip velocity function is crack-like, there is a prompt fluid <span class="hlt">pressure</span> rise at the onset of slip, followed by a slower increase. The stress drop associated with the prompt fluid <span class="hlt">pressure</span> rise increases with rupture propagation distance. The threshold propagation distance at which thermally induced stress drop starts to dominate over frictionally induced stress drop is proportional to hydraulic diffusivity. If hydraulic diffusivity is 0.02 m2/s, estimated from borehole samples of fault zone material, the threshold propagation distance is 300 m. The stress wave in an earthquake will induce an unknown amount of dilatancy and will increase hydraulic diffusivity, both of which will lessen the fluid <span class="hlt">pressure</span> effect. Nevertheless, if hydraulic diffusivity is no more than two orders of magnitude larger than the laboratory value, then stress drop is complete in large earthquakes.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014NatGe...7..292M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014NatGe...7..292M"><span>Locking of the Chile subduction zone controlled by fluid <span class="hlt">pressure</span> before the 2010 earthquake</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Moreno, Marcos; Haberland, Christian; Oncken, Onno; Rietbrock, Andreas; Angiboust, Samuel; Heidbach, Oliver</p> <p>2014-04-01</p> <p>Constraints on the potential size and recurrence time of strong subduction-zone earthquakes come from the degree of locking between the down-going and overriding plates, in the period between large earthquakes. In many cases, this interseismic locking degree correlates with slip during large earthquakes or is attributed to variations in fluid content at the plate interface. Here we use geodetic and seismological data to explore the links between <span class="hlt">pore</span>-fluid <span class="hlt">pressure</span> and locking patterns at the subduction interface ruptured during the magnitude 8.8 Chile earthquake in 2010. High-resolution three-dimensional seismic tomography reveals variations in the ratio of seismic P- to S-wave velocities (Vp/Vs) along the length of the subduction-zone interface. High Vp/Vs domains, interpreted as zones of elevated <span class="hlt">pore</span>-fluid <span class="hlt">pressure</span>, correlate spatially with parts of the plate interface that are poorly locked and slip aseismically. In contrast, low Vp/Vs domains, interpreted as zones of lower <span class="hlt">pore</span>-fluid <span class="hlt">pressure</span>, correlate with locked parts of the plate interface, where unstable slip and earthquakes occur. Variations in <span class="hlt">pore</span>-fluid <span class="hlt">pressure</span> are caused by the subduction and dehydration of a hydrothermally altered oceanic fracture zone. We conclude that variations in <span class="hlt">pore</span>-fluid <span class="hlt">pressure</span> at the plate interface control the degree of interseismic locking and therefore the slip distribution of large earthquake ruptures.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/pages/biblio/1341685-mouthpart-conduit-sizes-fluid-feeding-insects-determine-ability-feed-from-pores','SCIGOV-DOEP'); return false;" href="https://www.osti.gov/pages/biblio/1341685-mouthpart-conduit-sizes-fluid-feeding-insects-determine-ability-feed-from-pores"><span>Mouthpart conduit sizes of fluid-feeding insects determine the ability to feed from <span class="hlt">pores</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/pages">DOE PAGES</a></p> <p>Lehnert, Matthew S.; Bennett, Andrew; Reiter, Kristen E.; ...</p> <p>2017-01-04</p> <p>Fluid-feeding insects, such as butterflies, moths, and flies (20% of all animal species), are faced with the common selection <span class="hlt">pressure</span> of having to remove and feed on trace amounts of fluids from porous surfaces. Insects able to acquire fluids that are confined to <span class="hlt">pores</span> during drought conditions would have an adaptive advantage and increased fitness over other individuals. Here we performed feeding trials using solutions with magnetic nanoparticles to show that butterflies and flies have mouthparts adapted to pull liquids from porous surfaces using capillary action as the governing principle. In addition, the ability to feed on the liquids collectedmore » from <span class="hlt">pores</span> depends on a relationship between the diameter of the mouthpart conduits and substrate <span class="hlt">pore</span> size diameter; insects with mouthpart conduit diameters larger than the <span class="hlt">pores</span> cannot successfully feed, thus there is a limiting substrate <span class="hlt">pore</span> size from which each species can acquire liquids for fluid uptake. In conclusion, given that natural selection independently favored mouthpart architectures that support these methods of fluid uptake (Diptera and Lepidoptera share a common ancestor 280 mya that had chewing mouthparts), we suggest that the convergence of this mechanism advocates this as an optimal strategy for pulling trace amounts of fluids from porous surfaces.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/servlets/purl/1341685','SCIGOV-STC'); return false;" href="https://www.osti.gov/servlets/purl/1341685"><span>Mouthpart conduit sizes of fluid-feeding insects determine the ability to feed from <span class="hlt">pores</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a></p> <p>Lehnert, Matthew S.; Bennett, Andrew; Reiter, Kristen E.</p> <p></p> <p>Fluid-feeding insects, such as butterflies, moths, and flies (20% of all animal species), are faced with the common selection <span class="hlt">pressure</span> of having to remove and feed on trace amounts of fluids from porous surfaces. Insects able to acquire fluids that are confined to <span class="hlt">pores</span> during drought conditions would have an adaptive advantage and increased fitness over other individuals. Here we performed feeding trials using solutions with magnetic nanoparticles to show that butterflies and flies have mouthparts adapted to pull liquids from porous surfaces using capillary action as the governing principle. In addition, the ability to feed on the liquids collectedmore » from <span class="hlt">pores</span> depends on a relationship between the diameter of the mouthpart conduits and substrate <span class="hlt">pore</span> size diameter; insects with mouthpart conduit diameters larger than the <span class="hlt">pores</span> cannot successfully feed, thus there is a limiting substrate <span class="hlt">pore</span> size from which each species can acquire liquids for fluid uptake. In conclusion, given that natural selection independently favored mouthpart architectures that support these methods of fluid uptake (Diptera and Lepidoptera share a common ancestor 280 mya that had chewing mouthparts), we suggest that the convergence of this mechanism advocates this as an optimal strategy for pulling trace amounts of fluids from porous surfaces.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/21575059','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/21575059"><span>Esophageal motor <span class="hlt">abnormalities</span> in eosinophilic esophagitis identified by high-resolution manometry.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Martín Martín, Leticia; Santander, Cecilio; Lopez Martín, Mari Carmen; Espinoza-Ríos, Jorge; Chavarría-Herbozo, Carlos; Gisbert, Javier P; Moreno-Otero, Ricardo</p> <p>2011-09-01</p> <p>Esophageal motility <span class="hlt">abnormalities</span>, as measured by conventional manometry (CM), are non-specific in the majority of patients with eosinophilic esophagitis (EoE). Moreover, the study of CM is limited by poor interobserver agreement. The aims of the present study were: (i) to assess the esophageal patterns in EoE by a topographic analysis of high-resolution manometry (HRM) data; and (ii) to establish a relationship between motility <span class="hlt">abnormalities</span> and symptoms of EoE, such as dysphagia and bolus impaction. All adult patients with EoE diagnosed according to histological criteria, and controls with gastroesophageal reflux disease symptoms and dysphagia, were included. HRM was done in EoE patients and controls. For the analysis of data, the Chicago classification was followed. HRM was performed in 21 patients with EoE, as well as in 21 controls. Of the 21 patients with EoE, 10 (48%) showed pan-esophageal <span class="hlt">pressurization</span>, six (28%) showed peristaltic dysfunction, and in five cases (24%), HRM was normal. There was no pan-esophageal <span class="hlt">pressurization</span> in controls. Nine of 10 patients with pan-esophageal <span class="hlt">pressurization</span> required endoscopic bolus removal (P < 0.05); none had obstructive endoscopy findings. The most frequent esophageal motor <span class="hlt">abnormality</span> measured by HRM was a pan-esophageal <span class="hlt">pressurization</span>. Bolus impaction in patients with EoE was associated with pan-esophageal <span class="hlt">pressurization</span>. © 2011 Journal of Gastroenterology and Hepatology Foundation and Blackwell Publishing Asia Pty Ltd.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016AGUFMMR41A2683S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016AGUFMMR41A2683S"><span>Micro X-ray CT Imaging of Sediments under Confining <span class="hlt">Pressure</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Schindler, M.; Prasad, M.</p> <p>2016-12-01</p> <p>We developed a <span class="hlt">pressure</span> and temperature control system for use inside the micro X-ray CT scanner Xradia 400. We succeeded in building a <span class="hlt">pressure</span> vessel that can be <span class="hlt">pressurized</span> to 34.5 MPa (5000 psi) while being transparent to X-rays. The setup can currently be cooled to -5°C and heated to 40°C. We were able to observe grain damage and porosity reduction due to applied confining <span class="hlt">pressure</span> in clean quartz sand samples and quartz sand and bentonite samples. By comparing micro CT images at atmospheric <span class="hlt">pressure</span> and 13.8 MPa (2000 psi) confining <span class="hlt">pressure</span>, we observed compaction of the samples resulting in grain damage and fracturing of sediment grains (Figure 1). When the confining <span class="hlt">pressure</span> was decreased some grains experienced further fracturing. The grain damage appears irreversible. Further fracturing of grains in pre-compacted sediment was observed upon repeated confining <span class="hlt">pressure</span> cycling. We are currently working on feed-throughs for fluid lines and electric wiring to use ultrasonic transducers and <span class="hlt">pressure</span> control in combination. Further we plan to include <span class="hlt">pore</span> <span class="hlt">pressure</span> in addition to confining <span class="hlt">pressure</span> into the system. The <span class="hlt">pressure</span> control system in combination with ultrasonic transducers will allow us to visually observe <span class="hlt">pore</span> scale changes in rock samples while simultaneously identifying their influence on ultrasonic velocities. Such <span class="hlt">pore</span>-scale changes are usually not taken into account by rock physics models and could help to identify why laboratory data diverges from theoretical models. Further, it is possible to compute compressibility from mCT images at different stress states by image correlation</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018JHyd..561..547N','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018JHyd..561..547N"><span>Evaluation of δ2H and δ18O of water in <span class="hlt">pores</span> extracted by compression method-effects of closed <span class="hlt">pores</span> and comparison to direct vapor equilibration and laser spectrometry method</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Nakata, Kotaro; Hasegawa, Takuma; Oyama, Takahiro; Miyakawa, Kazuya</p> <p>2018-06-01</p> <p>Stable isotopes (δ2H and δ18O) of water can help our understanding of origin, mixing and migration of groundwater. In the formation with low permeability, it provides information about migration mechanism of ion such as diffusion and/or advection. Thus it has been realized as very important information to understand the migration of water and ions in it. However, in formation with low permeability it is difficult to obtain the ground water sample as liquid and water in <span class="hlt">pores</span> needs to be extracted to estimate it. Compressing rock is the most common and widely used method of extracting water in <span class="hlt">pores</span>. However, changes in δ2H and δ18O may take place during compression because changes in ion concentration have been reported in previous studies. In this study, two natural rocks were compressed, and the changes in the δ2H and δ18O with compression <span class="hlt">pressure</span> were investigated. Mechanisms for the changes in water isotopes observed during the compression were then discussed. In addition, δ2H and δ18O of water in <span class="hlt">pores</span> were also evaluated by direct vapor equilibration and laser spectrometry (DVE-LS) and δ2H and δ18O were compared with those obtained by compression. δ2H was found to change during the compression and a part of this change was found to be explained by the effect of water from closed <span class="hlt">pores</span> extracted by compression. In addition, water isotopes in both open and closed <span class="hlt">pores</span> were estimated by combining the results of 2 kinds of compression experiments. Water isotopes evaluated by compression that not be affected by water from closed <span class="hlt">pores</span> showed good agreements with those obtained by DVE-LS indicating compression could show the mixed information of water from open and closed <span class="hlt">pores</span>, while DVE-LS could show the information only for open <span class="hlt">pores</span>. Thus, the comparison of water isotopes obtained by compression and DVE-LS could provide the information about water isotopes in closed and open <span class="hlt">pores</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/16112680','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/16112680"><span>Low-<span class="hlt">pressure</span> argon adsorption assessment of micropore connectivities in activated carbons.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Zimny, T; Villieras, F; Finqueneisel, G; Cossarutto, L; Weber, J V</p> <p>2006-01-01</p> <p>Low-<span class="hlt">pressure</span> argon adsorption has been used to study the energetic distribution of microporous activated carbons differing by their burn-off. The collected isotherms were analyzed using the derivative isotherm summation method. Some oscillations on the experimental curves for very low partial <span class="hlt">pressures</span> were detected. The results are analyzed and discussed according to the literature and could be attributed to local overheating caused by spontaneous mass transfer of argon through constrictions between former <span class="hlt">pores</span> and the new opening <span class="hlt">pore</span> or deadend <span class="hlt">pores</span>. We used the dynamic character of the experimental method and mainly the discrepancy of the quasi-equilibrium state to deduce key parameters related to the porosity topology.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017AGUFMMR13C..04S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017AGUFMMR13C..04S"><span>Estimating dynamic permeability in fractal <span class="hlt">pore</span> network saturated by Maxwellian fluid</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Sun, W.</p> <p>2017-12-01</p> <p>The frequency dependent flow of fluid in porous media is an important issue in geophysical prospecting. Oscillating flow in pipe leads to frequency dependent dynamic permeability and has been studied in <span class="hlt">pore</span> network containing Newtonian fluid. But there is little work on oscillating complex fluid in pipe network, especially in irregular network. Here we formulated frequency dependent permeability for Maxwellian fluid and estimated the permeability in three-dimensional fractal network model. We consider an infinitely long cylindrical pipe with rigid solid wall. The pipe is filled with Maxwellian fluids. Based on the mass conservation equation, the equilibrium equation of force and Maxwell constitutive relationship, we formulated the flux by integration of axial velocity component over the pipe's cross section. Then we extend single pipe formulation to a 3D irregular network. Flux balance condition yields a set of linear equations whose unknowns are the fluid <span class="hlt">pressure</span> at each node. By evaluating the total flow flux through the network, the dynamic permeability can be calculated.We investigated the dynamic permeability of brine and CPyCl/NaSal in a 3D porous sample with a cubic side length 1 cm. The <span class="hlt">pore</span> network is created by a Voronoi cell filling method. The porosity, i.e., volume ratio between <span class="hlt">pore</span>/pipe network and the overall cubic, is set as 0.1. The irregular <span class="hlt">pore</span> network has a fractal structure. The dimension d of the <span class="hlt">pore</span> network is defined by the relation between node number M within a sphere and the radius r of the sphere,M=rd.The results show that both brine and Maxwellian fluid's permeability maintain a stable value at low frequency, then decreases with fluctuating peaks. The dynamic permeability in <span class="hlt">pore</span> networks saturated by Maxwellian fluid (CPyCl/NaSal (60 mM)) show larger peaks during the decline process at high frequency, which represents the typical resonance behavior. Dynamic permeability shows clear dependence on the dimension of the fractal</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016JGRB..121.7929B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016JGRB..121.7929B"><span>Investigating the relative permeability behavior of microporosity-rich carbonates and tight sandstones with multiscale <span class="hlt">pore</span> network models</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Bultreys, Tom; Stappen, Jeroen Van; Kock, Tim De; Boever, Wesley De; Boone, Marijn A.; Hoorebeke, Luc Van; Cnudde, Veerle</p> <p>2016-11-01</p> <p>The relative permeability behavior of rocks with wide ranges of <span class="hlt">pore</span> sizes is in many cases still poorly understood and is difficult to model at the <span class="hlt">pore</span> scale. In this work, we investigate the capillary <span class="hlt">pressure</span> and relative permeability behavior of three outcrop carbonates and two tight reservoir sandstones with wide, multimodal <span class="hlt">pore</span> size distributions. To examine how the drainage and imbibition properties of these complex rock types are influenced by the connectivity of macropores to each other and to zones with unresolved small-scale porosity, we apply a previously presented microcomputed-tomography-based multiscale <span class="hlt">pore</span> network model to these samples. The sensitivity to the properties of the small-scale porosity is studied by performing simulations with different artificial sphere-packing-based networks as a proxy for these <span class="hlt">pores</span>. Finally, the mixed-wet water-flooding behavior of the samples is investigated, assuming different wettability distributions for the microporosity and macroporosity. While this work is not an attempt to perform predictive modeling, it seeks to qualitatively explain the behavior of the investigated samples and illustrates some of the most recent developments in multiscale <span class="hlt">pore</span> network modeling.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/23005784','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/23005784"><span>NMR-based diffusion <span class="hlt">pore</span> imaging.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Laun, Frederik Bernd; Kuder, Tristan Anselm; Wetscherek, Andreas; Stieltjes, Bram; Semmler, Wolfhard</p> <p>2012-08-01</p> <p>Nuclear magnetic resonance (NMR) diffusion experiments offer a unique opportunity to study boundaries restricting the diffusion process. In a recent Letter [Phys. Rev. Lett. 107, 048102 (2011)], we introduced the idea and concept that such diffusion experiments can be interpreted as NMR imaging experiments. Consequently, images of closed <span class="hlt">pores</span>, in which the spins diffuse, can be acquired. In the work presented here, an in-depth description of the diffusion <span class="hlt">pore</span> imaging technique is provided. Image artifacts due to gradient profiles of finite duration, field inhomogeneities, and surface relaxation are considered. Gradients of finite duration lead to image blurring and edge enhancement artifacts. Field inhomogeneities have benign effects on diffusion <span class="hlt">pore</span> images, and surface relaxation can lead to a shrinkage and shift of the <span class="hlt">pore</span> image. The relation between boundary structure and the imaginary part of the diffusion weighted signal is analyzed, and it is shown that information on <span class="hlt">pore</span> coherence can be obtained without the need to measure the phase of the diffusion weighted signal. Moreover, it is shown that quite arbitrary gradient profiles can be used for diffusion <span class="hlt">pore</span> imaging. The matrices required for numerical calculations are stated and provided as supplemental material.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/29176624','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/29176624"><span>A statistical image analysis framework for <span class="hlt">pore</span>-free islands derived from heterogeneity distribution of nuclear <span class="hlt">pore</span> complexes.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Mimura, Yasuhiro; Takemoto, Satoko; Tachibana, Taro; Ogawa, Yutaka; Nishimura, Masaomi; Yokota, Hideo; Imamoto, Naoko</p> <p>2017-11-24</p> <p>Nuclear <span class="hlt">pore</span> complexes (NPCs) maintain cellular homeostasis by mediating nucleocytoplasmic transport. Although cyclin-dependent kinases (CDKs) regulate NPC assembly in interphase, the location of NPC assembly on the nuclear envelope is not clear. CDKs also regulate the disappearance of <span class="hlt">pore</span>-free islands, which are nuclear envelope subdomains; this subdomain gradually disappears with increase in homogeneity of the NPC in response to CDK activity. However, a causal relationship between <span class="hlt">pore</span>-free islands and NPC assembly remains unclear. Here, we elucidated mechanisms underlying NPC assembly from a new perspective by focusing on <span class="hlt">pore</span>-free islands. We proposed a novel framework for image-based analysis to automatically determine the detailed 'landscape' of <span class="hlt">pore</span>-free islands from a large quantity of images, leading to the identification of NPC intermediates that appear in <span class="hlt">pore</span>-free islands with increased frequency in response to CDK activity. Comparison of the spatial distribution between simulated and the observed NPC intermediates within <span class="hlt">pore</span>-free islands showed that their distribution was spatially biased. These results suggested that the disappearance of <span class="hlt">pore</span>-free islands is highly related to de novo NPC assembly and indicated the existence of specific regulatory mechanisms for the spatial arrangement of NPC assembly on nuclear envelopes.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017AGUFM.H11G1283L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017AGUFM.H11G1283L"><span>Experimental Quantification of <span class="hlt">Pore</span>-Scale Flow Phenomena in 2D Heterogeneous Porous Micromodels: Multiphase Flow Towards Coupled Solid-Liquid Interactions</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Li, Y.; Kazemifar, F.; Blois, G.; Christensen, K. T.</p> <p>2017-12-01</p> <p>Geological sequestration of CO2 within saline aquifers is a viable technology for reducing CO2 emissions. Central to this goal is accurately predicting both the fidelity of candidate sites pre-injection of CO2 and its post-injection migration. Moreover, local fluid <span class="hlt">pressure</span> buildup may cause activation of small pre-existing unidentified faults, leading to micro-seismic events, which could prove disastrous for societal acceptance of CCS, and possibly compromise seal integrity. Recent evidence shows that large-scale events are coupled with <span class="hlt">pore</span>-scale phenomena, which necessitates the representation of <span class="hlt">pore</span>-scale stress, strain, and multiphase flow processes in large-scale modeling. To this end, the <span class="hlt">pore</span>-scale flow of water and liquid/supercritical CO2 is investigated under reservoir-relevant conditions, over a range of wettability conditions in 2D heterogeneous micromodels that reflect the complexity of a real sandstone. High-speed fluorescent microscopy, complemented by a fast differential <span class="hlt">pressure</span> transmitter, allows for simultaneous measurement of the flow field within and the instantaneous <span class="hlt">pressure</span> drop across the micromodels. A flexible micromodel is also designed and fabricated, to be used in conjunction with the micro-PIV technique, enabling the quantification of coupled solid-liquid interactions.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4934177','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4934177"><span>Investigating Hydrophilic <span class="hlt">Pores</span> in Model Lipid Bilayers using Molecular Simulations: Correlating Bilayer Properties with <span class="hlt">Pore</span> Formation Thermodynamics</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Hu, Yuan; Sinha, Sudipta Kumar</p> <p>2015-01-01</p> <p>Cell-penetrating and antimicrobial peptides show remarkable ability to translocate across physiological membranes. Along with factors such as electric potential induced-perturbations of membrane structure and surface tension effects, experiments invoke <span class="hlt">pore</span>-like membrane configurations during the solute transfer process into vesicles and cells. The initiation and formation of <span class="hlt">pores</span> are associated with a non-trivial free energy cost, thus necessitating consideration of the factors associated with <span class="hlt">pore</span> formation and attendant free energetics. Due to experimental and modeling challenges related to the long timescales of the translocation process, we use umbrella-sampling molecular dynamics simulations with a lipid-density based order parameter to investigate membrane <span class="hlt">pore</span>-formation free energy employing Martini coarse-grained models. We investigate structure and thermodynamic features of the <span class="hlt">pore</span> in 18 lipids spanning a range of head-groups, charge states, acyl chain lengths and saturation. We probe the dependence of <span class="hlt">pore</span>-formation barriers on area per lipid, lipid bilayer thickness, membrane bending rigidities in three different lipid classes. The <span class="hlt">pore</span> formation free energy in pure bilayers and peptide translocating scenarios are significantly coupled with bilayer thickness. Thicker bilayers require more reversible work to create <span class="hlt">pores</span>. <span class="hlt">Pore</span> formation free energy is higher in peptide-lipid systems relative to the peptide-free lipid systems due to penalties to maintain solvation of charged hydrophilic solutes within the membrane environment. PMID:25614183</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017LaPhL..14f5601B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017LaPhL..14f5601B"><span>Laser-assisted formation of micropores and nanobubbles in sclera promote stable normalization of intraocular <span class="hlt">pressure</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Baum, Olga; Wachsmann-Hogiu, Sebastian; Milner, Thomas; Sobol, Emil</p> <p>2017-06-01</p> <p><span class="hlt">Pores</span> in sclera enhance uveoscleral water outflow and can normalize intraocular <span class="hlt">pressure</span> in glaucomatous eyes. The aims of this study are to demonstrate laser-induced formation of <span class="hlt">pores</span> with a dendritic structure and to answer the questions: How is a <span class="hlt">pore</span> system stable and can laser treatment provide a long-lasting <span class="hlt">pressure</span> stabilization effect? Effect of 1.56 µm laser radiation on porcine eye sclera was studied using atomic force microscopy and super resolution structured irradiation microscopy with fluorescent markers. Results suggest that the <span class="hlt">pores</span> with a complex spatial configuration can arise as a result of laser irradiation and that laser-generated stable gas nanobubbles coated with calcium ions allow <span class="hlt">pore</span> stabilization in the sclera. Our results support a laser based approach for treatment of glaucoma.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1999JChPh.110.4867M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1999JChPh.110.4867M"><span>Freezing and melting of water in a single cylindrical <span class="hlt">pore</span>: The <span class="hlt">pore</span>-size dependence of freezing and melting behavior</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Morishige, Kunimitsu; Kawano, Keiji</p> <p>1999-03-01</p> <p>In order to clarify the origin of the hysteresis between freezing and melting of <span class="hlt">pore</span> water, we performed x-ray diffraction measurements of water confined inside the cylindrical <span class="hlt">pores</span> of seven kinds of siliceous MCM-41 (a member of ordered mesoporous materials denoted by Mobil Oil researchers) with different <span class="hlt">pore</span> radii (1.2-2.9 nm) and the interconnected <span class="hlt">pores</span> of Vycor glass as a function of temperature. The hysteresis effect depends markedly on the size of the cylindrical <span class="hlt">pores</span>: the hysteresis is negligibly small in smaller <span class="hlt">pores</span> and becomes remarkable in larger <span class="hlt">pores</span>. This strongly suggests that the hysteresis is arisen from size-dependent supercooling of water confined to the mesopores. For the water confined to the mesopores with <span class="hlt">pore</span> radius of 1.2 nm, a continuous transition between a liquid and a solid precedes the first-order freezing transition of the <span class="hlt">pore</span> water which would occur by the same mechanism as in bulk water.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3035924','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3035924"><span>Fabrication, properties, and applications of porous metals with directional <span class="hlt">pores</span></span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>NAKAJIMA, Hideo</p> <p>2010-01-01</p> <p>Lotus-type porous metals with aligned long cylindrical <span class="hlt">pores</span> are fabricated by unidirectional solidification from the melt with a dissolved gas such as hydrogen, nitrogen, or oxygen. The gas atoms can be dissolved into the melt via a <span class="hlt">pressurized</span> gas atmosphere or thermal decomposition of gaseous compounds. Three types of solidification techniques have been developed: mold casting, continuous zone melting, and continuous casting techniques. The last method is superior from the viewpoint of mass production of lotus metals. The observed anisotropic behaviors of the mechanical properties, sound absorption, and thermal conductivity are inherent to the anisotropic porous structure. In particular, the remarkable anisotropy in the mechanical strength is attributed to the stress concentration around the <span class="hlt">pores</span> aligned perpendicular to the loading direction. Heat sinks are a promising application of lotus metals due to the high cooling performance with a large heat transfer. PMID:21084772</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/biblio/335452','DOE-PATENT-XML'); return false;" href="https://www.osti.gov/biblio/335452"><span>Porous silicon structures with high surface area/specific <span class="hlt">pore</span> size</span></a></p> <p><a target="_blank" href="http://www.osti.gov/doepatents">DOEpatents</a></p> <p>Northrup, M.A.; Yu, C.M.; Raley, N.F.</p> <p>1999-03-16</p> <p>Fabrication and use of porous silicon structures to increase surface area of heated reaction chambers, electrophoresis devices, and thermopneumatic sensor-actuators, chemical preconcentrates, and filtering or control flow devices. In particular, such high surface area or specific <span class="hlt">pore</span> size porous silicon structures will be useful in significantly augmenting the adsorption, vaporization, desorption, condensation and flow of liquids and gases in applications that use such processes on a miniature scale. Examples that will benefit from a high surface area, porous silicon structure include sample preconcentrators that are designed to adsorb and subsequently desorb specific chemical species from a sample background; chemical reaction chambers with enhanced surface reaction rates; and sensor-actuator chamber devices with increased <span class="hlt">pressure</span> for thermopneumatic actuation of integrated membranes. Examples that benefit from specific <span class="hlt">pore</span> sized porous silicon are chemical/biological filters and thermally-activated flow devices with active or adjacent surfaces such as electrodes or heaters. 9 figs.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li class="active"><span>17</span></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_17 --> <div id="page_18" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li class="active"><span>18</span></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="341"> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/servlets/purl/872190','DOE-PATENT-XML'); return false;" href="https://www.osti.gov/servlets/purl/872190"><span>Porous silicon structures with high surface area/specific <span class="hlt">pore</span> size</span></a></p> <p><a target="_blank" href="http://www.osti.gov/doepatents">DOEpatents</a></p> <p>Northrup, M. Allen; Yu, Conrad M.; Raley, Norman F.</p> <p>1999-01-01</p> <p>Fabrication and use of porous silicon structures to increase surface area of heated reaction chambers, electrophoresis devices, and thermopneumatic sensor-actuators, chemical preconcentrates, and filtering or control flow devices. In particular, such high surface area or specific <span class="hlt">pore</span> size porous silicon structures will be useful in significantly augmenting the adsorption, vaporization, desorption, condensation and flow of liquids and gasses in applications that use such processes on a miniature scale. Examples that will benefit from a high surface area, porous silicon structure include sample preconcentrators that are designed to adsorb and subsequently desorb specific chemical species from a sample background; chemical reaction chambers with enhanced surface reaction rates; and sensor-actuator chamber devices with increased <span class="hlt">pressure</span> for thermopneumatic actuation of integrated membranes. Examples that benefit from specific <span class="hlt">pore</span> sized porous silicon are chemical/biological filters and thermally-activated flow devices with active or adjacent surfaces such as electrodes or heaters.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014EGUGA..1614470M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014EGUGA..1614470M"><span>Dynamic <span class="hlt">Pore</span>-Scale Imaging of Reactive Transport in Heterogeneous Carbonates at Reservior Conditions</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Menke, Hannah; Bijeljic, Branko; Andrew, Matthew; Blunt, Martin</p> <p>2014-05-01</p> <p>Sequestering carbon in deep geologic formations is one way of reducing anthropogenic CO2 emissions. Carbon capture, Utilization, and Storage (CCUS) in carbonate reservoirs has the added benefit of mobilizing more oil for extraction, increasing oil reservoir yield, and generating revenue while also mitigating climate change. The magnitude, speed, and type of dissolution are dependent the intrinsic properties of the rock. Understanding how small changes in the <span class="hlt">pore</span> structure affect dissolution is paramount for successful predictive modelling both on the <span class="hlt">pore</span>-scale and for up-scaled reservoir simulations. We propose an experimental method whereby both 'Pink Beam' synchrotron radiation and a Micro-CT lab source are used in dynamic X-ray microtomography to investigate the <span class="hlt">pore</span> structure changes in carbonate rocks of varying heterogeneity at high temperatures and <span class="hlt">pressures</span>. Four carbonate rock types were studied, two relatively homogeneous carbonates, Ketton and Mt. Gambier, and two very heterogeneous carbonates, Estalliades and Portland Basebed. Each rock type was imaged under the same reservoir and flow conditions to gain insight into the impact of heterogeneity. A 4-mm carbonate core was injected with CO2-saturated brine at 10 MPa and 50oC for 2 hours. Depending on sample heterogeneity and X-ray source, tomographic images were taken at between 30-second and 20-minute time-resolutions and a 4-micron spatial resolution during injection. Changes in porosity, permeability, and structure were obtained by first binning and filtering the images, then binarizing them with watershed segmentation, and finally extracting a <span class="hlt">pore</span>/throat network. Furthermore, <span class="hlt">pore</span>-scale flow modelling was performed directly on the binarized image and used to track velocity distributions as the <span class="hlt">pore</span> network evolved. Significant differences in dissolution type and magnitude were found for each rock type. The most homogeneous carbonate, Ketton, was seen to have predominately uniform dissolution with</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016APS..DFDD37010K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016APS..DFDD37010K"><span><span class="hlt">Pore</span>-scale modeling of moving contact line problems in immiscible two-phase flow</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kucala, Alec; Noble, David; Martinez, Mario</p> <p>2016-11-01</p> <p>Accurate modeling of moving contact line (MCL) problems is imperative in predicting capillary <span class="hlt">pressure</span> vs. saturation curves, permeability, and preferential flow paths for a variety of applications, including geological carbon storage (GCS) and enhanced oil recovery (EOR). Here, we present a model for the moving contact line using <span class="hlt">pore</span>-scale computational fluid dynamics (CFD) which solves the full, time-dependent Navier-Stokes equations using the Galerkin finite-element method. The MCL is modeled as a surface traction force proportional to the surface tension, dependent on the static properties of the immiscible fluid/solid system. We present a variety of verification test cases for simple two- and three-dimensional geometries to validate the current model, including threshold <span class="hlt">pressure</span> predictions in flows through <span class="hlt">pore</span>-throats for a variety of wetting angles. Simulations involving more complex geometries are also presented to be used in future simulations for GCS and EOR problems. Sandia is a multiprogram laboratory operated by Sandia Corporation, a Lockheed Martin Company, for the United States Department of Energy's National Nuclear Security Administration under contract DE-AC04-94AL85000.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/26906727','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26906727"><span>Measuring kinetic drivers of pneumolysin <span class="hlt">pore</span> structure.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Gilbert, Robert J C; Sonnen, Andreas F-P</p> <p>2016-05-01</p> <p>Most membrane attack complex-perforin/cholesterol-dependent cytolysin (MACPF/CDC) proteins are thought to form <span class="hlt">pores</span> in target membranes by assembling into pre-<span class="hlt">pore</span> oligomers before undergoing a pre-<span class="hlt">pore</span> to <span class="hlt">pore</span> transition. Assembly during <span class="hlt">pore</span> formation is into both full rings of subunits and incomplete rings (arcs). The balance between arcs and full rings is determined by a mechanism dependent on protein concentration in which arc <span class="hlt">pores</span> arise due to kinetic trapping of the pre-<span class="hlt">pore</span> forms by the depletion of free protein subunits during oligomerization. Here we describe the use of a kinetic assay to study <span class="hlt">pore</span> formation in red blood cells by the MACPF/CDC pneumolysin from Streptococcus pneumoniae. We show that cell lysis displays two kinds of dependence on protein concentration. At lower concentrations, it is dependent on the pre-<span class="hlt">pore</span> to <span class="hlt">pore</span> transition of arc oligomers, which we show to be a cooperative process. At higher concentrations, it is dependent on the amount of pneumolysin bound to the membrane and reflects the affinity of the protein for its receptor, cholesterol. A lag occurs before cell lysis begins; this is dependent on oligomerization of pneumolysin. Kinetic dissection of cell lysis by pneumolysin demonstrates the capacity of MACPF/CDCs to generate <span class="hlt">pore</span>-forming oligomeric structures of variable size with, most likely, different functional roles in biology.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018RScI...89d4904J','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018RScI...89d4904J"><span>Extension of the thermal porosimetry method to high gas <span class="hlt">pressure</span> for nanoporosimetry estimation</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Jannot, Y.; Degiovanni, A.; Camus, M.</p> <p>2018-04-01</p> <p>Standard <span class="hlt">pore</span> size determination methods like mercury porosimetry, nitrogen sorption, microscopy, or X-ray tomography are not suited to highly porous, low density, and thus very fragile materials. For this kind of materials, a method based on thermal characterization has been developed in a previous study. This method has been used with air <span class="hlt">pressure</span> varying from 10-1 to 105 Pa for materials having a thermal conductivity less than 0.05 W m-1 K-1 at atmospheric <span class="hlt">pressure</span>. It enables the estimation of <span class="hlt">pore</span> size distribution between 100 nm and 1 mm. In this paper, we present a new experimental device enabling thermal conductivity measurement under gas <span class="hlt">pressure</span> up to 106 Pa, enabling the estimation of the volume fraction of <span class="hlt">pores</span> having a 10 nm diameter. It is also demonstrated that the main thermal conductivity models (parallel, series, Maxwell, Bruggeman, self-consistent) lead to the same estimation of the <span class="hlt">pore</span> size distribution as the extended parallel model (EPM) presented in this paper and then used to process the experimental data. Three materials with thermal conductivities at atmospheric <span class="hlt">pressure</span> ranging from 0.014 W m-1 K-1 to 0.04 W m-1 K-1 are studied. The thermal conductivity measurement results obtained with the three materials are presented, and the corresponding <span class="hlt">pore</span> size distributions between 10 nm and 1 mm are presented and discussed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017EGUGA..19.9905O','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017EGUGA..19.9905O"><span>Critical Evaluation of Soil <span class="hlt">Pore</span> Water Extraction Methods on a Natural Soil</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Orlowski, Natalie; Pratt, Dyan; Breuer, Lutz; McDonnell, Jeffrey</p> <p>2017-04-01</p> <p>Soil <span class="hlt">pore</span> water extraction is an important component in ecohydrological studies for the measurement of δ2H and δ18O. The effect of <span class="hlt">pore</span> water extraction technique on resultant isotopic signature is poorly understood. Here we present results of an intercomparison of commonly applied lab-based soil water extraction techniques on a natural soil: high <span class="hlt">pressure</span> mechanical squeezing, centrifugation, direct vapor equilibration, microwave extraction, and two types of cryogenic extraction systems. We applied these extraction methods to a natural summer-dry (gravimetric water contents ranging from 8% to 15%) glacio-lacustrine, moderately fine textured clayey soil; excavated in 10 cm sampling increments to a depth of 1 meter. Isotope results were analyzed via OA-ICOS and compared for each extraction technique that produced liquid water. From our previous intercomparison study among the same extraction techniques but with standard soils, we discovered that extraction methods are not comparable. We therefore tested the null hypothesis that all extraction techniques would be able to replicate the natural evaporation front in a comparable manner occurring in a summer-dry soil. Our results showed that the extraction technique utilized had a significant effect on the soil water isotopic composition. High <span class="hlt">pressure</span> mechanical squeezing and vapor equilibration techniques produced similar results with similarly sloped evaporation lines. Due to the nature of soil properties and dryness, centrifugation was unsuccessful in obtaining <span class="hlt">pore</span> water for isotopic analysis. Cryogenic extraction on both tested techniques produced similar results to each other on a similar sloping evaporation line, but dissimilar with depth.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1999SedG..123..129C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1999SedG..123..129C"><span><span class="hlt">Pore</span> water evolution in sandstones of the Groundhog Coalfield, northern Bowser Basin, British Columbia</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Cookenboo, H. O.; Bustin, R. M.</p> <p>1999-01-01</p> <p> petroleum, high-<span class="hlt">pressure</span> methane, and methane-rich aqueous solutions. Homogenization temperatures from primary two-phase inclusions are consistent with quartz cementation during progressive heating between approximately 100 and 200°C. Following quartz precipitation, alkaline <span class="hlt">pore</span> waters were re-established, as evidenced by late-stage calcite cement (stage 7).</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015AGUFMMR33A2634M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AGUFMMR33A2634M"><span>Correlation between <span class="hlt">pore</span> fluid <span class="hlt">pressures</span> and DInSAR post-seismic deformation of the May 20, 2012 Emilia-Romagna (Italy) earthquake</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Moro, M.; Stramondo, S.; Albano, M.; Barba, S.; Solaro, G.; Saroli, M.; Bignami, C.</p> <p>2015-12-01</p> <p>The present work focuses on the detection and analysis of the postseismic surface deformations following the two earthquakes that hit the Emilia Romagna region (Italy) on May 20 and 29, 2012. The 2012 Emilia earthquake sequence struck the central sector of the Ferrara arc, which represents the external fold-and-thrust system of the Northern Apennines thrust belt buried below the Po plain. The May 20 event occurred on the Ferrara basal thrust at depth, at about 6-7 km, while, during the May 29 event, the rupture jumped on an inner splay of the Ferrara system. The analysis of the postseismic displacements was carried out thanks to a dataset of SAR COSMO­ SkyMed images covering a time span of about one year (May 20, 2012 - May 11, 2013) after the May 20 event. The DInSAR results revealed the presence of two deformation patches: the first one is located in the area that experienced the coseismic uplift. Here the postseismic displacements point out a further ground uplift occurring along the first three months after the 20 May event. The second deformation patch is located in the villages of San Carlo and Mirabello, where ground subsidence lasting about four months was detected. We hypothesized that both the observed phenomena are related to the <span class="hlt">pore</span> <span class="hlt">pressure</span> perturbation caused by the coseismic deformation. In particular, the ground uplift is due to the deep crustal deformations caused by the <span class="hlt">pore</span> fluid diffusion at depth to re-establish the initial hydrostatic stresses. Instead, the ground subsidence is related to the compaction of the shallow sandy layers caused by the liquefaction phenomena, which widely affected the San Carlo and Mirabello area. Preliminary numerical analyses performed with the Finite Element Method and empirical relations confirmed our hypothesis.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017APS..DFDD14008W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017APS..DFDD14008W"><span>Storage and recovery of methane-ethane mixtures in single shale <span class="hlt">pores</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Wu, Haiyi; Qiao, Rui</p> <p>2017-11-01</p> <p>Natural gas production from shale formations has received extensive attention recently. While great progress has been made in understanding the adsorption and transport of single-component gas inside shales' nanopores, the adsorption and transport of multicomponent shale gas under reservoir conditions (CH4 and C2H6 mixture) has only begun to be studied. In this work, we use molecular simulations to compute the storage of CH4 and C2H6 mixtures in single nanopores and their subsequent recovery. We show that surface adsorption contributes greatly to the storage of CH4 and C2H6 inside the <span class="hlt">pores</span> and C2H6 is enriched over CH4. The enrichment of C2H6 is enhanced as the <span class="hlt">pore</span> is narrowed, but is weakened as the <span class="hlt">pressure</span> increases. We show that the recovery of gas mixtures from the nanopores approximately follows the diffusive scaling law. The ratio of the production rates of C2H6 and CH4 is close to their initial mole ratio inside the <span class="hlt">pore</span> despite that the mobility of pure C2H6 is much smaller than that of pure CH4 inside the <span class="hlt">pores</span>. By using scale analysis, we show that the strong coupling between the transport of CH4 and C2H6 is responsible for the effective recovery of C2H6 from the nanopores.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/28569260','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/28569260"><span>Association of left ventricular structural and functional <span class="hlt">abnormalities</span> with aortic and brachial blood <span class="hlt">pressure</span> variability in hypertensive patients: the SAFAR study.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Chi, C; Yu, S-K; Auckle, R; Argyris, A A; Nasothimiou, E; Tountas, C; Aissopou, E; Blacher, J; Safar, M E; Sfikakis, P P; Zhang, Y; Protogerou, A D</p> <p>2017-10-01</p> <p>Both brachial blood <span class="hlt">pressure</span> (BP) level and its variability (BPV) significantly associate with left ventricular (LV) structure and function. Recent studies indicate that aortic BP is superior to brachial BP in the association with LV <span class="hlt">abnormalities</span>. However, it remains unknown whether aortic BPV better associate with LV structural and functional <span class="hlt">abnormalities</span>. We therefore aimed to investigate and compare aortic versus brachial BPV, in terms of the identification of LV <span class="hlt">abnormalities</span>. Two hundred and three participants who underwent echocardiography were included in this study. Twenty-four-hour aortic and brachial ambulatory BP was measured simultaneously by a validated BP monitor (Mobil-O-Graph, Stolberg, Germany) and BPV was calculated with validated formulae. LV mass and LV diastolic dysfunction (LVDD) were evaluated by echocardiography. The prevalence of LV hypertrophy (LVH) and LVDD increased significantly with BPV indices (P⩽0.04) in trend tests. After adjustment to potential confounders, only aortic average real variability (ARV), but not brachial ARV or weighted s.d. (wSD, neither aortic nor brachial) significantly associated with LV mass index (P=0.02). Similar results were observed in logistic regression. After adjustment, only aortic ARV significantly associated with LVH (odds ratio (OR) and 95% confidence interval (CI): 2.28 (1.08, 4.82)). As for LVDD, neither the brachial nor the aortic 24-hour wSD, but the aortic and brachial ARV, associated with LVDD significantly, with OR=2.28 (95% CI: (1.03, 5.02)) and OR=2.36 (95% CI: (1.10, 5.05)), respectively. In summary, aortic BPV, especially aortic ARV, seems to be superior to brachial BPV in the association of LV structural and functional <span class="hlt">abnormalities</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017MeScT..28j5901K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017MeScT..28j5901K"><span>Analyzer for measuring gas contained in the <span class="hlt">pore</span> space of rocks</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kudasik, Mateusz; Skoczylas, Norbert</p> <p>2017-10-01</p> <p>In the present paper, the authors discussed the functioning of their own analyzer for measuring gas contained in the <span class="hlt">pore</span> space of high strength rocks. A sample is placed inside a hermetic measuring chamber, and then undergoes impact milling as a result of colliding with the vibrating blade of a knife which is rotationally driven by a high-speed brushless electric motor. The measuring chamber is equipped with all the necessary sensors, i.e. gas, <span class="hlt">pressure</span>, and temperature sensors. Trial tests involving the comminution of dolomite and anhydrite samples demonstrated that the constructed device is able to break up rocks into grains so fine that they are measured in single microns, and the sensors used in the construction ensure balancing of the released gas. The tests of the analyzer showed that the metrological concept behind it, together with the way it was built, make it fit for measurements of the content and composition of selected gases from the rock <span class="hlt">pore</span> space. On the basis of the conducted tests of balancing the gases contained in the two samples, it was stated that the gas content of Sample no. 1 was (0.055  ±  0.002) cm3 g-1, and Sample no. 2 contained gas at atmospheric <span class="hlt">pressure</span>, composed mostly of air.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015EGUGA..1714255S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015EGUGA..1714255S"><span>Can ash clog soil <span class="hlt">pores</span>?</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Stoof, Cathelijne; Stoof, Cathelijne; Gevaert, Anouk; Gevaert, Anouk; Baver, Christine; Baver, Christine; Hassanpour, Bahareh; Hassanpour, Bahareh; Morales, Veronica; Morales, Veronica; Zhang, Wei; Zhang, Wei; Martin, Deborah; Martin, Deborah; Steenhuis, Tammo; Steenhuis, Tammo</p> <p>2015-04-01</p> <p>Wildfire can greatly increase a landscape's vulnerability to flooding and erosion events, and ash is thought to play a large role in controlling runoff and erosion processes after wildfire. Although ash can store rainfall and thereby reduce runoff and erosion for a limited period after wildfires, it has also been hypothesized to clog soil <span class="hlt">pores</span> and reduce infiltration. Several researchers have attributed the commonly observed increase in runoff and erosion after fire to the potential <span class="hlt">pore</span>-clogging effect of ash. Evidence is however incomplete, as to date, research has solely focused on identifying the presence of ash in the soil, with the actual flow processes associated with the infiltration and <span class="hlt">pore</span>-clogging of ash remaining a major unknown. In several laboratory experiments, we tested the hypothesis that ash causes <span class="hlt">pore</span> clogging to the point that infiltration is hampered and ponding occurs. We first visualized and quantified <span class="hlt">pore</span>-scale infiltration of water and ash in sand of a range of textures and at various infiltration rates, using a digital bright field microscope capturing both photo and video. While these visualization experiments confirm field and lab observation of ash washing into soil <span class="hlt">pores</span>, we did not observe any clogging of <span class="hlt">pores</span>, and have not been able to create conditions for which this does occur. Additional electrochemical analysis and measurement of saturated hydraulic conductivity indicate that <span class="hlt">pore</span> clogging by ash is not plausible. Electrochemical analysis showed that ash and sand are both negatively charged, showing that attachment of ash to sand and any resulting clogging is unlikely. Ash also had quite high saturated conductivity, and systems where ash was mixed in or lying on top of sand had similarly high hydraulic conductivity. Based on these various experiments, we cannot confirm the hypothesis that <span class="hlt">pore</span> clogging by ash contributes to the frequently observed increase in post-fire runoff, at least for the medium to coarse sands</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5353574','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5353574"><span>Logical Issues With the <span class="hlt">Pressure</span> Natriuresis Theory of Chronic Hypertension</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>DiCarlo, Stephen E.; Morris, R. Curtis</p> <p>2016-01-01</p> <p>Abstract The term “<span class="hlt">abnormal</span> <span class="hlt">pressure</span> natriuresis” refers to a subnormal effect of a given level of blood <span class="hlt">pressure</span> (BP) on sodium excretion. It is widely believed that <span class="hlt">abnormal</span> <span class="hlt">pressure</span> natriuresis causes an initial increase in BP to be sustained. We refer to this view as the “<span class="hlt">pressure</span> natriuresis theory of chronic hypertension.” The proponents of the theory contend that all forms of chronic hypertension are sustained by <span class="hlt">abnormal</span> <span class="hlt">pressure</span> natriuresis, irrespective of how hypertension is initiated. This theory would appear to follow from “the three laws of long-term arterial <span class="hlt">pressure</span> regulation” stated by Guyton and Coleman more than 3 decades ago. These “laws” articulate the concept that for a given level of salt intake, the relationship between arterial <span class="hlt">pressure</span> and sodium excretion determines the chronic level of BP. Here, we review and examine the recent assertion by Beard that these “laws” of long-term BP control amount to nothing more than a series of tautologies. Our analysis supports Beard’s assertion, and also indicates that contemporary investigators often use tautological reasoning in support of the <span class="hlt">pressure</span> natriuresis theory of chronic hypertension. Although the theory itself is not a tautology, it does not appear to be testable because it holds that <span class="hlt">abnormal</span> <span class="hlt">pressure</span> natriuresis causes salt-induced hypertension to be sustained through <span class="hlt">abnormal</span> increases in cardiac output that are too small to be detected. PMID:28637271</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/25614183','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/25614183"><span>Investigating Hydrophilic <span class="hlt">Pores</span> in Model Lipid Bilayers Using Molecular Simulations: Correlating Bilayer Properties with <span class="hlt">Pore</span>-Formation Thermodynamics.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Hu, Yuan; Sinha, Sudipta Kumar; Patel, Sandeep</p> <p>2015-06-23</p> <p>Cell-penetrating and antimicrobial peptides show a remarkable ability to translocate across physiological membranes. Along with factors such as electric-potential-induced perturbations of membrane structure and surface tension effects, experiments invoke porelike membrane configurations during the solute transfer process into vesicles and cells. The initiation and formation of <span class="hlt">pores</span> are associated with a nontrivial free-energy cost, thus necessitating a consideration of the factors associated with <span class="hlt">pore</span> formation and the attendant free energies. Because of experimental and modeling challenges related to the long time scales of the translocation process, we use umbrella sampling molecular dynamics simulations with a lipid-density-based order parameter to investigate membrane-<span class="hlt">pore</span>-formation free energy employing Martini coarse-grained models. We investigate structure and thermodynamic features of the <span class="hlt">pore</span> in 18 lipids spanning a range of headgroups, charge states, acyl chain lengths, and saturation. We probe the dependence of <span class="hlt">pore</span>-formation barriers on the area per lipid, lipid bilayer thickness, and membrane bending rigidities in three different lipid classes. The <span class="hlt">pore</span>-formation free energy in pure bilayers and peptide translocating scenarios are significantly coupled with bilayer thickness. Thicker bilayers require more reversible work to create <span class="hlt">pores</span>. The <span class="hlt">pore</span>-formation free energy is higher in peptide-lipid systems than in peptide-free lipid systems due to penalties to maintain the solvation of charged hydrophilic solutes within the membrane environment.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/6527253','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/6527253"><span>Dissolution at porous interfaces VI: Multiple <span class="hlt">pore</span> systems.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Grijseels, H; Crommelin, D J; De Blaey, C J</p> <p>1984-12-01</p> <p>With the aid of rapidly dissolving sodium chloride particles, cubic <span class="hlt">pores</span> were made in the surface of a theophylline tablet. The influence of the <span class="hlt">pores</span> on the dissolution rate of the surface was investigated in a rotating disk apparatus. Like the drilled <span class="hlt">pores</span> used in earlier studies, downstream on the surface they caused a turbulent flow regimen with the development of a trough due to enhanced erosion. The phenomenon of a critical <span class="hlt">pore</span> diameter, discovered with single, drilled <span class="hlt">pores</span>, seems to be applicable to the cubic <span class="hlt">pores</span> investigated in this study, although a higher degree of surface coverage with <span class="hlt">pores</span> caused complications, probably due to particles bordering one another and forming larger <span class="hlt">pores</span>. The behavior of the porous surfaces at different rotation speeds was studied. Due to the presence of <span class="hlt">pores</span> the laminar character of the boundary layer flow changes to turbulent, which induces locally an increased dissolution flux in the wake of a <span class="hlt">pore</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2001AGUSM...H41C01W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2001AGUSM...H41C01W"><span>Visualizing and Quantifying <span class="hlt">Pore</span> Scale Fluid Flow Processes With X-ray Microtomography</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Wildenschild, D.; Hopmans, J. W.; Vaz, C. M.; Rivers, M. L.</p> <p>2001-05-01</p> <p>When using mathematical models based on Darcy's law it is often necessary to simplify geometry, physics or both and the capillary bundle-of-tubes approach neglects a fundamentally important characteristic of porous solids, namely interconnectedness of the <span class="hlt">pore</span> space. New approaches to <span class="hlt">pore</span>-scale modeling that arrange capillary tubes in two- or three-dimensional <span class="hlt">pore</span> space have been and are still under development: Network models generally represent the <span class="hlt">pore</span> space by spheres while the <span class="hlt">pore</span> throats are usually represented by cylinders or conical shapes. Lattice Boltzmann approaches numerically solve the Navier-Stokes equations in a realistic microscopically disordered geometry, which offers the ability to study the microphysical basis of macroscopic flow without the need for a simplified geometry or physics. In addition to these developments in numerical modeling techniques, new theories have proposed that interfacial area should be considered as a primary variable in modeling of a multi-phase flow system. In the wake of this progress emerges an increasing need for new ways of evaluating <span class="hlt">pore</span>-scale models, and for techniques that can resolve and quantify phase interfaces in porous media. The mechanisms operating at the <span class="hlt">pore</span>-scale cannot be measured with traditional experimental techniques, however x-ray computerized microtomography (CMT) provides non-invasive observation of, for instance, changing fluid phase content and distribution on the <span class="hlt">pore</span> scale. Interfacial areas have thus far been measured indirectly, but with the advances in high-resolution imaging using CMT it is possible to track interfacial area and curvature as a function of phase saturation or capillary <span class="hlt">pressure</span>. We present results obtained at the synchrotron-based microtomography facility (GSECARS, sector 13) at the Advanced Photon Source at Argonne National Laboratory. Cylindrical sand samples of either 6 or 1.5 mm diameter were scanned at different stages of drainage and for varying boundary</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017WRR....53.7457L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017WRR....53.7457L"><span>Visualization and quantification of capillary drainage in the <span class="hlt">pore</span> space of laminated sandstone by a porous plate method using differential imaging X-ray microtomography</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Lin, Qingyang; Bijeljic, Branko; Rieke, Holger; Blunt, Martin J.</p> <p>2017-08-01</p> <p>The experimental determination of capillary <span class="hlt">pressure</span> drainage curves at the <span class="hlt">pore</span> scale is of vital importance for the mapping of reservoir fluid distribution. To fully characterize capillary drainage in a complex <span class="hlt">pore</span> space, we design a differential imaging-based porous plate (DIPP) method using X-ray microtomography. For an exemplar mm-scale laminated sandstone microcore with a porous plate, we quantify the displacement from resolvable macropores and subresolution micropores. Nitrogen (N2) was injected as the nonwetting phase at a constant <span class="hlt">pressure</span> while the porous plate prevented its escape. The measured porosity and capillary <span class="hlt">pressure</span> at the imaged saturations agree well with helium measurements and experiments on larger core samples, while providing a <span class="hlt">pore</span>-scale explanation of the fluid distribution. We observed that the majority of the brine was displaced by N2 in macropores at low capillary <span class="hlt">pressures</span>, followed by a further brine displacement in micropores when capillary <span class="hlt">pressure</span> increases. Furthermore, we were able to discern that brine predominantly remained within the subresolution micropores, such as regions of fine lamination. The capillary <span class="hlt">pressure</span> curve for <span class="hlt">pressures</span> ranging from 0 to 1151 kPa is provided from the image analysis compares well with the conventional porous plate method for a cm-scale core but was conducted over a period of 10 days rather than up to few months with the conventional porous plate method. Overall, we demonstrate the capability of our method to provide quantitative information on two-phase saturation in heterogeneous core samples for a wide range of capillary <span class="hlt">pressures</span> even at scales smaller than the micro-CT resolution.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/biblio/1033163-direct-measurements-pore-fluid-density-vibrating-tube-densimetry','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/1033163-direct-measurements-pore-fluid-density-vibrating-tube-densimetry"><span>Direct Measurements of <span class="hlt">Pore</span> Fluid Density by Vibrating Tube Densimetry</span></a></p> <p><a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a></p> <p>Gruszkiewicz, Miroslaw S.; Rother, Gernot; Wesolowski, David J.</p> <p>2012-02-27</p> <p>The densities of <span class="hlt">pore</span>-confined fluids were measured for the first time by means of a vibrating tube method. Isotherms of total adsorption capacity were measured directly making the method complementary to the conventional gravimetric or volumetric/piezometric adsorption techniques, which yield the excess adsorption (the Gibbsian surface excess). A custom-made high-<span class="hlt">pressure</span>, high-temperature vibrating tube densimeter (VTD) was used to measure the densities of subcritical and supercritical propane (between 35 °C and 97 °C) and supercritical carbon dioxide (between 32 C and 50°C) saturating hydrophobic silica aerogel (0.2 g/cm 3, 90% porosity) synthesized inside Hastelloy U-tubes. Additionally, excess adsorption isotherms for supercriticalmore » CO 2 and the same porous solid were measured gravimetrically using a precise magnetically-coupled microbalance. <span class="hlt">Pore</span> fluid densities and total adsorption isotherms increased monotonically with increasing density of the bulk fluid, in contrast to excess adsorption isotherms, which reached a maximum at a subcritical density of the bulk fluid, and then decreased towards zero or negative values at supercritical densities. Compression of the confined fluid significantly beyond the density of the bulk liquid at the same temperature was observed at subcritical temperatures. The features of the isotherms of confined fluid density are interpreted to elucidate the observed behavior of excess adsorption. The maxima of excess adsorption were found to occur below the critical density of the bulk fluid at the conditions corresponding to the beginning of the plateau of total adsorption, marking the end of the transition of <span class="hlt">pore</span> fluid to a denser, liquid-like <span class="hlt">pore</span> phase. The results for propane and carbon dioxide showed similarity in the sense of the principle of corresponding states. No measurable effect of <span class="hlt">pore</span> confinement on the liquid-vapor critical point was found. Quantitative agreement was obtained between excess adsorption</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018GeoJI.214...70H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018GeoJI.214...70H"><span>An effective medium approach to modelling the <span class="hlt">pressure</span>-dependent electrical properties of porous rocks</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Han, Tongcheng</p> <p>2018-07-01</p> <p>Understanding the electrical properties of rocks under varying <span class="hlt">pressure</span> is important for a variety of geophysical applications. This study proposes an approach to modelling the <span class="hlt">pressure</span>-dependent electrical properties of porous rocks based on an effective medium model. The so-named Textural model uses the aspect ratios and <span class="hlt">pressure</span>-dependent volume fractions of the <span class="hlt">pores</span> and the aspect ratio and electrical conductivity of the matrix grains. The <span class="hlt">pores</span> were represented by randomly oriented stiff and compliant spheroidal shapes with constant aspect ratios, and their <span class="hlt">pressure</span>-dependent volume fractions were inverted from the measured variation of total porosity with differential <span class="hlt">pressure</span> using a dual porosity model. The unknown constant stiff and compliant <span class="hlt">pore</span> aspect ratios and the aspect ratio and electrical conductivity of the matrix grains were inverted by best fitting the modelled electrical formation factor to the measured data. Application of the approach to three sandstone samples covering a broad porosity range showed that the <span class="hlt">pressure</span>-dependent electrical properties can be satisfactorily modelled by the proposed approach. The results demonstrate that the dual porosity concept is sufficient to explain the electrical properties of porous rocks under <span class="hlt">pressure</span> through the effective medium model scheme.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/29067399','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/29067399"><span>Determination of <span class="hlt">pore</span>-scale hydrate phase equilibria in sediments using lab-on-a-chip technology.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Almenningen, Stian; Flatlandsmo, Josef; Kovscek, Anthony R; Ersland, Geir; Fernø, Martin A</p> <p>2017-11-21</p> <p>We present an experimental protocol for fast determination of hydrate stability in porous media for a range of <span class="hlt">pressure</span> and temperature (P, T) conditions. Using a lab-on-a-chip approach, we gain direct optical access to dynamic <span class="hlt">pore</span>-scale hydrate formation and dissociation events to study the hydrate phase equilibria in sediments. Optical <span class="hlt">pore</span>-scale observations of phase behavior reproduce the theoretical hydrate stability line with methane gas and distilled water, and demonstrate the accuracy of the new method. The procedure is applicable for any kind of hydrate transitions in sediments, and may be used to map gas hydrate stability zones in nature.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li class="active"><span>18</span></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_18 --> <div id="page_19" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li class="active"><span>19</span></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="361"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016AGUFM.T51B2914L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016AGUFM.T51B2914L"><span><span class="hlt">Pressure</span> prediction in non-uniaxial settings based on field data and geomechanical modeling: a well example</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Lockhart, L. P.; Flemings, P. B.; Nikolinakou, M. A.; Heidari, M.</p> <p>2016-12-01</p> <p>We apply a new <span class="hlt">pressure</span> prediction approach that couples sonic velocity data, geomechanical modeling, and a critical state soil model to estimate <span class="hlt">pore</span> <span class="hlt">pressure</span> from wellbore data adjacent to a salt body where the stress field is complex. Specifically, we study <span class="hlt">pressure</span> and stress in front of the Mad Dog salt body, in the Gulf of Mexico. Because of the loading from the salt, stresses are not uniaxial; the horizontal stress is elevated, leading to higher mean and shear stresses. For the Mad Dog field, we develop a relationship between velocity and equivalent effective stress, in order to account for both the mean and shear stress effect on <span class="hlt">pore</span> <span class="hlt">pressure</span>. We obtain this equivalent effective stress using a geomechanical model of the Mad Dog field. We show that the new approach improves <span class="hlt">pressure</span> prediction in areas near salt where mean and shear stress are different than the control well. Our methodology and results show that <span class="hlt">pore</span> <span class="hlt">pressure</span> is driven by a combination of mean stress and shear stress, and highlight the importance of shear-induced <span class="hlt">pore</span> <span class="hlt">pressures</span>. Furthermore, the impact of our study extends beyond salt bodies; the methodology and gained insights are applicable to geological environments around the world with a complex geologic history, where the stress state is not uniaxial (fault zones, anticlines, synclines, continental margins, etc.).</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/24071593','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/24071593"><span>A thermodynamic approach to alamethicin <span class="hlt">pore</span> formation.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Rahaman, Asif; Lazaridis, Themis</p> <p>2014-01-01</p> <p>The structure and energetics of alamethicin Rf30 monomer to nonamer in cylindrical <span class="hlt">pores</span> of 5 to 11Å radius are investigated using molecular dynamics simulations in an implicit membrane model that includes the free energy cost of acyl chain hydrophobic area exposure. Stable, low energy <span class="hlt">pores</span> are obtained for certain combinations of radius and oligomeric number. The trimer and the tetramer formed 6Å <span class="hlt">pores</span> that appear closed while the larger oligomers formed open <span class="hlt">pores</span> at their optimal radius. The hexamer in an 8Å <span class="hlt">pore</span> and the octamer in an 11Å <span class="hlt">pore</span> give the lowest effective energy per monomer. However, all oligomers beyond the pentamer have comparable energies, consistent with the observation of multiple conductance levels. The results are consistent with the widely accepted "barrel-stave" model. The N terminal portion of the molecule exhibits smaller tilt with respect to the membrane normal than the C terminal portion, resulting in a <span class="hlt">pore</span> shape that is a hybrid between a funnel and an hourglass. Transmembrane voltage has little effect on the structure of the oligomers but enhances or decreases their stability depending on its orientation. Antiparallel bundles are lower in energy than the commonly accepted parallel ones and could be present under certain experimental conditions. Dry aggregates (without an aqueous <span class="hlt">pore</span>) have lower average effective energy than the corresponding aggregates in a <span class="hlt">pore</span>, suggesting that alamethicin <span class="hlt">pores</span> may be excited states that are stabilized in part by voltage and in part by the ion flow itself. © 2013.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/biblio/6299657-pore-wall-roughness-fractal-surface-theoretical-simulation-mercury-intrusion-retraction-porous-media','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/6299657-pore-wall-roughness-fractal-surface-theoretical-simulation-mercury-intrusion-retraction-porous-media"><span><span class="hlt">Pore</span>-wall roughness as a fractal surface and theoretical simulation of mercury intrusion/retraction in porous media</span></a></p> <p><a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a></p> <p>Tsakiroglou, C.D.; Payatakes, A.C.</p> <p></p> <p>The mercury intrusion/retraction curves of many types of porous materials (e.g., sandstones) have sections of finite slope in the region of high and very high <span class="hlt">pressure</span>. This feature is attributed to the existence of microroughness on the <span class="hlt">pore</span> walls. In the present work <span class="hlt">pore</span>-wall roughness features are added to a three-dimensional primary network of chambers-and-throats using ideas of fractal geometry. The roughness of the throats is modeled with a finite number of self-similar triangular prisms of progressively smaller sizes. The roughness of the chambers is modeled in a similar way using right circular cones instead of prisms. Three parameters sufficemore » for the complete characterization of the model of fractal roughness, namely, the number of features per unit length, the common angle of sharpness, and the number of layers (which is taken to be the same for throats and chambers). Analytical relations that give the surface area, <span class="hlt">pore</span> volume, and mercury saturation of the <span class="hlt">pore</span> network as functions of the fractal roughness parameters are developed for monolayer and multilayer arrangements. The chamber-and-throat network with fractal <span class="hlt">pore</span>-wall roughness is used to develop an extended version of the computer-aided simulator of mercury porosimetry that has been reported in previous publications. This new simulator is used to investigate the effects of the roughness features on the form of mercury intrusion/retraction curves. It turns out that the fractal model of the porewall roughness gives an adequate representation of real porous media, and capillary <span class="hlt">pressure</span> curves which are similar to the experimental ones for many typical porous materials such as sandstones. The method is demonstrated with the analysis of a Greek sandstone.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/28564488','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/28564488"><span>Noninvasive beat-to-beat finger arterial <span class="hlt">pressure</span> monitoring during orthostasis: a comprehensive review of normal and <span class="hlt">abnormal</span> responses at different ages.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>van Wijnen, V K; Finucane, C; Harms, M P M; Nolan, H; Freeman, R L; Westerhof, B E; Kenny, R A; Ter Maaten, J C; Wieling, W</p> <p>2017-12-01</p> <p>Over the past 30 years, noninvasive beat-to-beat blood <span class="hlt">pressure</span> (BP) monitoring has provided great insight into cardiovascular autonomic regulation during standing. Although traditional sphygmomanometric measurement of BP may be sufficient for detection of sustained orthostatic hypotension, it fails to capture the complexity of the underlying dynamic BP and heart rate responses. With the emerging use of noninvasive beat-to-beat BP monitoring for the assessment of orthostatic BP control in clinical and population studies, various definitions for <span class="hlt">abnormal</span> orthostatic BP patterns have been used. Here, age-related changes in cardiovascular control in healthy subjects will be reviewed to define the spectrum of the most important <span class="hlt">abnormal</span> orthostatic BP patterns within the first 180 s of standing. <span class="hlt">Abnormal</span> orthostatic BP responses can be defined as initial orthostatic hypotension (a transient systolic BP fall of >40 mmHg within 15 s of standing), delayed BP recovery (an inability of systolic BP to recover to a value of >20 mmHg below baseline at 30 s after standing) and sustained orthostatic hypotension (a sustained decline in systolic BP of ≥20 mmHg occurring 60-180 s after standing). In the evaluation of patients with light-headedness, pre(syncope), (unexplained) falls or suspected autonomic dysfunction, it is essential to distinguish between normal cardiovascular autonomic regulation and these <span class="hlt">abnormal</span> orthostatic BP responses. The prevalence, clinical relevance and underlying pathophysiological mechanisms of these patterns differ significantly across the lifespan. Initial orthostatic hypotension is important for identifying causes of syncope in younger adults, whereas delayed BP recovery and sustained orthostatic hypotension are essential for evaluating the risk of falls in older adults. © 2017 The Authors Journal of Internal Medicine published by John Wiley & Sons Ltd on behalf of Association for Publication of The Journal of Internal Medicine.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/27726258','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/27726258"><span>Nitrogen-mediated effects of elevated CO2 on intra-aggregate soil <span class="hlt">pore</span> structure.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Caplan, Joshua S; Giménez, Daniel; Subroy, Vandana; Heck, Richard J; Prior, Stephen A; Runion, G Brett; Torbert, H Allen</p> <p>2017-04-01</p> <p>Soil <span class="hlt">pore</span> structure has a strong influence on water retention, and is itself influenced by plant and microbial dynamics such as root proliferation and microbial exudation. Although increased nitrogen (N) availability and elevated atmospheric CO 2 concentrations (eCO 2 ) often have interacting effects on root and microbial dynamics, it is unclear whether these biotic effects can translate into altered soil <span class="hlt">pore</span> structure and water retention. This study was based on a long-term experiment (7 yr at the time of sampling) in which a C 4 pasture grass (Paspalum notatum) was grown on a sandy loam soil while provided factorial additions of N and CO 2 . Through an analysis of soil aggregate fractal properties supported by 3D microtomographic imagery, we found that N fertilization induced an increase in intra-aggregate porosity and a simultaneous shift toward greater accumulation of <span class="hlt">pore</span> space in larger aggregates. These effects were enhanced by eCO 2 and yielded an increase in water retention at <span class="hlt">pressure</span> potentials near the wilting point of plants. However, eCO 2 alone induced changes in the opposite direction, with larger aggregates containing less <span class="hlt">pore</span> space than under control conditions, and water retention decreasing accordingly. Results on biotic factors further suggested that organic matter gains or losses induced the observed structural changes. Based on our results, we postulate that the <span class="hlt">pore</span> structure of many mineral soils could undergo N-dependent changes as atmospheric CO 2 concentrations rise, having global-scale implications for water balance, carbon storage, and related rhizosphere functions. © 2016 John Wiley & Sons Ltd.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017AdWR..108....1R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017AdWR..108....1R"><span><span class="hlt">Pore</span>-scale modeling of capillary trapping in water-wet porous media: A new cooperative <span class="hlt">pore</span>-body filling model</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ruspini, L. C.; Farokhpoor, R.; Øren, P. E.</p> <p>2017-10-01</p> <p>We present a <span class="hlt">pore</span>-network model study of capillary trapping in water-wet porous media. The amount and distribution of trapped non-wetting phase is determined by the competition between two trapping mechanisms - snap-off and cooperative <span class="hlt">pore</span>-body filling. We develop a new model to describe the <span class="hlt">pore</span>-body filling mechanism in geologically realistic <span class="hlt">pore</span>-networks. The model accounts for the geometrical characteristics of the <span class="hlt">pore</span>, the spatial location of the connecting throats and the local fluid topology at the time of the displacement. We validate the model by comparing computed capillary trapping curves with published data for four different water-wet rocks. Computations are performed on <span class="hlt">pore</span>-networks extracted from micro-CT images and process-based reconstructions of the actual rocks used in the experiments. Compared with commonly used stochastic models, the new model describes more accurately the experimental measurements, especially for well connected porous systems where trapping is controlled by subtleties of the <span class="hlt">pore</span> structure. The new model successfully predicts relative permeabilities and residual saturation for Bentheimer sandstone using in-situ measured contact angles as input to the simulations. The simulated trapped cluster size distributions are compared with predictions from percolation theory.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017EGUGA..1918729T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017EGUGA..1918729T"><span>Mercury porosimetry for comparing piece-wise hydraulic properties with full range <span class="hlt">pore</span> characteristics of soil aggregates and porous rocks</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Turturro, Antonietta Celeste; Caputo, Maria C.; Gerke, Horst H.</p> <p>2017-04-01</p> <p>Unsaturated hydraulic properties are essential in the modeling of water and solute movement in the vadose zone. Since standard hydraulic techniques are limited to specific moisture ranges, maybe affected by air entrapment, wettability problems, limitations due to water vapor <span class="hlt">pressure</span>, and are depending on the initial saturation, the continuous maximal drying curves of the complete hydraulic functions can mostly not reflect the basic <span class="hlt">pore</span> size distribution. The aim of this work was to compare the water retention curves of soil aggregates and porous rocks with their porosity characteristics. Soil aggregates of Haplic Luvisols from Loess L (Hneveceves, Czech Republic) and glacial Till T (Holzendorf, Germany) and two lithotypes of porous rock C (Canosa) and M (Massafra), Italy, were analyzed using, suction table, evaporation, psychrometry methods, and the adopted Quasi-Steady Centrifuge method for determination of unsaturated hydraulic conductivity. These various water-based techniques were applied to determine the piece-wise retention and the unsaturated hydraulic conductivity functions in the range of <span class="hlt">pore</span> water saturations. The <span class="hlt">pore</span>-size distribution was determined with the mercury intrusion porosimetry (MIP). MIP results allowed assessing the volumetric mercury content at applied <span class="hlt">pressures</span> up to 420000 kPa. Greater intrusion and porosity values were found for the porous rocks than for the soil aggregates. Except for the aggregate samples from glacial till, maximum liquid contents were always smaller than porosity. Multimodal porosities and retention curves were observed for both porous rocks and aggregate soils. Two <span class="hlt">pore</span>-size peaks with <span class="hlt">pore</span> diameters of 0.135 and 27.5 µm, 1.847 and 19.7 µm, and 0.75 and 232 µm were found for C, M and T, respectively, while three peaks of 0.005, 0.392 and 222 µm were identified for L. The MIP data allowed describing the retention curve in the entire mercury saturation range as compared to water retention curves that required</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011AGUFM.S41C2201T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011AGUFM.S41C2201T"><span>High fluid <span class="hlt">pressure</span> and triggered earthquakes in the enhanced geothermal system in Basel, Switzerland</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Terakawa, T.; Miller, S. A.; Deichmann, N.</p> <p>2011-12-01</p> <p>We estimate the <span class="hlt">pore</span> fluid <span class="hlt">pressure</span> field of the stimulated region during the fluid injection experiment in Basel, Switzerland by analyzing 118 well-constrained focal mechanisms. This technique, termed focal mechanism tomography (FMT), uses the orientations of the slip planes within the prevailing regional stress field as indicator of the fluid <span class="hlt">pressure</span> along the plane at the time of slip. Elevated <span class="hlt">pore</span> fluid <span class="hlt">pressures</span> were concentrated within 500 m of the open hole section, and we find average earthquake triggering excess <span class="hlt">pressures</span> of about 10MPa, with a peak value of 19.3 MPa, consistent with the known wellhead <span class="hlt">pressure</span> applied at the borehole. Our results demonstrate that FMT is a robust approach, being validated at the macroscopic scale of the Basel stimulation experiment. Over-<span class="hlt">pressurized</span> fluids induced many small events (M < 3) along faults unfavourably-oriented relative to the tectonic stress pattern, while larger events tended to occur along optimally-oriented faults. This suggests that small-scale hydraulic networks, developed from the high <span class="hlt">pressure</span> stimulation, interact to load (hydraulically isolated) high strength bridges that produce the larger events. The triggering <span class="hlt">pore</span> fluid <span class="hlt">pressures</span> are substantially higher than that predicted from a linear <span class="hlt">pressure</span> diffusion process from the source boundary, showing that the system is highly permeable along flow paths, allowing fast <span class="hlt">pressure</span> diffusion to the boundaries of the stimulated region.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/25738415','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/25738415"><span>Dynamic three-dimensional <span class="hlt">pore</span>-scale imaging of reaction in a carbonate at reservoir conditions.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Menke, Hannah P; Bijeljic, Branko; Andrew, Matthew G; Blunt, Martin J</p> <p>2015-04-07</p> <p>Quantifying CO2 transport and average effective reaction rates in the subsurface is essential to assess the risks associated with underground carbon capture and storage. We use X-ray microtomography to investigate dynamic <span class="hlt">pore</span> structure evolution in situ at temperatures and <span class="hlt">pressures</span> representative of underground reservoirs and aquifers. A 4 mm diameter Ketton carbonate core is injected with CO2-saturated brine at 50 °C and 10 MPa while tomographic images are taken at 15 min intervals with a 3.8 μm spatial resolution over a period of 2(1/2) h. An approximate doubling of porosity with only a 3.6% increase in surface area to volume ratio is measured from the images. <span class="hlt">Pore</span>-scale direct simulation and network modeling on the images quantify an order of magnitude increase in permeability and an appreciable alteration of the velocity field. We study the uniform reaction regime, with dissolution throughout the core. However, at the <span class="hlt">pore</span> scale, we see variations in the degree of dissolution with an overall reaction rate which is approximately 14 times lower than estimated from batch measurements. This work implies that in heterogeneous rocks, <span class="hlt">pore</span>-scale transport of reactants limits dissolution and can reduce the average effective reaction rate by an order of magnitude.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015PCM....42..509S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015PCM....42..509S"><span>High-<span class="hlt">pressure</span> synthesis of mesoporous stishovite: potential applications in mineral physics</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Stagno, Vincenzo; Mandal, Manik; Landskron, Kai; Fei, Yingwei</p> <p>2015-06-01</p> <p>Recently, we have described a successful synthesis route to obtain mesoporous quartz and its high-<span class="hlt">pressure</span> polymorph coesite by nanocasting at high <span class="hlt">pressure</span> using periodic mesostructured precursors, such as SBA-16 and FDU-12/carbon composite as starting materials. Periodic mesoporous high-<span class="hlt">pressure</span> silica polymorphs are of particular interest as they combine transport properties and physical properties such as hardness that potentially enable the industrial use of these materials. In addition, synthesis of mesoporous crystalline silica phases can allow more detailed geology-related studies such as water/mineral interaction, dissolution/crystallization rate and the surface contribution to the associated thermodynamic stability (free energy and enthalpy) of the various polymorphs and their crossover. Here, we present results of synthesis of mesoporous stishovite from cubic large-<span class="hlt">pore</span> periodic mesoporous silica LP-FDU-12/C composite as precursor with an fcc lattice. We describe the synthesis procedure using multi-anvil apparatus at 9 GPa (about 90,000 atm) and temperature of 500 °C. The synthetic mesoporous stishovite is, then, characterized by wide and small-angle X-ray diffraction, scanning/transmission electron microscopy and gas adsorption. Results show that this new material is characterized by accessible mesopores with wide <span class="hlt">pore</span> size distribution, surface area of ~45 m2/g and volume of <span class="hlt">pores</span> of ~0.15 cm3/g. Results from gas adsorption indicate that both porosity and permeability are retained at the high <span class="hlt">pressures</span> of synthesis but with weak periodic order of the <span class="hlt">pores</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/22086337','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/22086337"><span><span class="hlt">Pore</span> surface engineering in covalent organic frameworks.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Nagai, Atsushi; Guo, Zhaoqi; Feng, Xiao; Jin, Shangbin; Chen, Xiong; Ding, Xuesong; Jiang, Donglin</p> <p>2011-11-15</p> <p>Covalent organic frameworks (COFs) are a class of important porous materials that allow atomically precise integration of building blocks to achieve pre-designable <span class="hlt">pore</span> size and geometry; however, <span class="hlt">pore</span> surface engineering in COFs remains challenging. Here we introduce <span class="hlt">pore</span> surface engineering to COF chemistry, which allows the controlled functionalization of COF <span class="hlt">pore</span> walls with organic groups. This functionalization is made possible by the use of azide-appended building blocks for the synthesis of COFs with walls to which a designable content of azide units is anchored. The azide units can then undergo a quantitative click reaction with alkynes to produce <span class="hlt">pore</span> surfaces with desired groups and preferred densities. The diversity of click reactions performed shows that the protocol is compatible with the development of various specific surfaces in COFs. Therefore, this methodology constitutes a step in the <span class="hlt">pore</span> surface engineering of COFs to realize pre-designed compositions, components and functions.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://pubs.er.usgs.gov/publication/70022524','USGSPUBS'); return false;" href="https://pubs.er.usgs.gov/publication/70022524"><span>Osmotic generation of 'anomalous' fluid <span class="hlt">pressures</span> in geological environments</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Neuzii, C.E.</p> <p>2000-01-01</p> <p>Osmotic <span class="hlt">pressures</span> are generated by differences in chemical potential of a solution across a membrane. But whether osmosis can have a significant effect on the <span class="hlt">pressure</span> of fluids in geological environments has been controversial, because the membrane properties of geological media are poorly understood. 'Anomalous' <span class="hlt">pressures</span> - large departures from hydrostatic <span class="hlt">pressure</span> that are not explicable in terms of topographic or fluid-density effects are widely found in geological settings, and are commonly considered to result from processes that alter the <span class="hlt">pore</span> or fluid volume, which in turn implies crustal changes happening at a rate too slow to observe directly. Yet if osmosis can explain some anomalies, there is no need to invoke such dynamic geological processes in those cases. Here I report results of a nine- year in situ measurement of fluid <span class="hlt">pressures</span> and solute concentrations in shale that are consistent with the generation of large (up to 20 MPa) osmotic-<span class="hlt">pressure</span> anomalies which could persist for tens of millions of years. Osmotic <span class="hlt">pressures</span> of this magnitude and duration can explain many of the <span class="hlt">pressure</span> anomalies observed in geological settings. The require, however, small shale porosity and large contrasts in the amount of dissolved solids in the <span class="hlt">pore</span> waters - criteria that may help to distinguish between osmotic and crystal-dynamic origins of anomalous <span class="hlt">pressures</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5171239','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5171239"><span>Reversible Self-Actuated Thermo-Responsive <span class="hlt">Pore</span> Membrane</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Park, Younggeun; Gutierrez, Maria Paz; Lee, Luke P.</p> <p>2016-01-01</p> <p>Smart membranes, which can selectively control the transfer of light, air, humidity and temperature, are important to achieve indoor climate regulation. Even though reversible self-actuation of smart membranes is desirable in large-scale, reversible self-regulation remains challenging. Specifically, reversible 100% opening/closing of <span class="hlt">pore</span> actuation showing accurate responsiveness, reproducibility and structural flexibility, including uniform structure assembly, is currently very difficult. Here, we report a reversible, thermo-responsive self-activated <span class="hlt">pore</span> membrane that achieves opening and closing of <span class="hlt">pores</span>. The reversible, self-actuated thermo-responsive <span class="hlt">pore</span> membrane was fabricated with hybrid materials of poly (N-isopropylacrylamide), (PNIPAM) within polytetrafluoroethylene (PTFE) to form a multi-dimensional <span class="hlt">pore</span> array. Using Multiphysics simulation of heat transfer and structural mechanics based on finite element analysis, we demonstrated that <span class="hlt">pore</span> opening and closing dynamics can be self-activated at environmentally relevant temperatures. Temperature cycle characterizations of the <span class="hlt">pore</span> structure revealed 100% opening ratio at T = 40 °C and 0% opening ratio at T = 20 °C. The flexibility of the membrane showed an accurate temperature-responsive function at a maximum bending angle of 45°. Addressing the importance of self-regulation, this reversible self-actuated thermo-responsive <span class="hlt">pore</span> membrane will advance the development of future large-scale smart membranes needed for sustainable indoor climate control. PMID:27991563</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016NatSR...639402P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016NatSR...639402P"><span>Reversible Self-Actuated Thermo-Responsive <span class="hlt">Pore</span> Membrane</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Park, Younggeun; Gutierrez, Maria Paz; Lee, Luke P.</p> <p>2016-12-01</p> <p>Smart membranes, which can selectively control the transfer of light, air, humidity and temperature, are important to achieve indoor climate regulation. Even though reversible self-actuation of smart membranes is desirable in large-scale, reversible self-regulation remains challenging. Specifically, reversible 100% opening/closing of <span class="hlt">pore</span> actuation showing accurate responsiveness, reproducibility and structural flexibility, including uniform structure assembly, is currently very difficult. Here, we report a reversible, thermo-responsive self-activated <span class="hlt">pore</span> membrane that achieves opening and closing of <span class="hlt">pores</span>. The reversible, self-actuated thermo-responsive <span class="hlt">pore</span> membrane was fabricated with hybrid materials of poly (N-isopropylacrylamide), (PNIPAM) within polytetrafluoroethylene (PTFE) to form a multi-dimensional <span class="hlt">pore</span> array. Using Multiphysics simulation of heat transfer and structural mechanics based on finite element analysis, we demonstrated that <span class="hlt">pore</span> opening and closing dynamics can be self-activated at environmentally relevant temperatures. Temperature cycle characterizations of the <span class="hlt">pore</span> structure revealed 100% opening ratio at T = 40 °C and 0% opening ratio at T = 20 °C. The flexibility of the membrane showed an accurate temperature-responsive function at a maximum bending angle of 45°. Addressing the importance of self-regulation, this reversible self-actuated thermo-responsive <span class="hlt">pore</span> membrane will advance the development of future large-scale smart membranes needed for sustainable indoor climate control.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/26840879','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26840879"><span><span class="hlt">Abnormal</span> findings in peers during skills learning.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Wearn, Andy; Nakatsuji, Miriam; Bhoopatkar, Harsh</p> <p>2017-02-01</p> <p>Peer physical examination (PPE), where students examine each other, is common in contemporary clinical skills learning. A range of benefits and risks have been explored in the literature. One persistent concern has been the identification and management of <span class="hlt">abnormal</span> physical findings. Two previous studies have attempted to quantify the risk, one through the discussion of two exemplar cases and the other with a retrospective student survey. Here, we report the first prospective study of the number and type of <span class="hlt">abnormalities</span> encountered as part of early clinical skills learning in a medical programme. We have a formal written consent process for PPE, which includes the management of <span class="hlt">abnormal</span> findings through the completion of an event form. Our data come from cohorts undertaking years 2 and 3 of the programme between 2003 and 2014. One persistent concern (of PPE) has been the identification and management of <span class="hlt">abnormal</span> physical findings RESULTS: Nineteen event forms were completed over this period. The incidence rates per year ranged from 0.23 to 1.05 per cent. <span class="hlt">Abnormal</span> findings included raised blood <span class="hlt">pressure</span>, heart murmur, <span class="hlt">abnormal</span> bedside test values, and eye and skin conditions. The low event rate, along with a feasible process for dealing with this issue, goes some way to reassuring those with concerns. We acknowledge that some <span class="hlt">abnormalities</span> may have been missed, and that some data may have been lost as a result of incorrect process; however, even the highest annual rate is low in absolute terms. We recommend a formal process for managing <span class="hlt">abnormalities</span>. Ideally this would be part of an overall PPE written policy, communicated to students, enacted by tutors and approved by the local ethics committee. © 2016 John Wiley & Sons Ltd.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016AdWR...95..109Y','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016AdWR...95..109Y"><span><span class="hlt">Pore</span>-scale simulations of drainage in granular materials: Finite size effects and the representative elementary volume</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Yuan, Chao; Chareyre, Bruno; Darve, Félix</p> <p>2016-09-01</p> <p>A <span class="hlt">pore</span>-scale model is introduced for two-phase flow in dense packings of polydisperse spheres. The model is developed as a component of a more general hydromechanical coupling framework based on the discrete element method, which will be elaborated in future papers and will apply to various processes of interest in soil science, in geomechanics and in oil and gas production. Here the emphasis is on the generation of a network of <span class="hlt">pores</span> mapping the void space between spherical grains, and the definition of local criteria governing the primary drainage process. The <span class="hlt">pore</span> space is decomposed by Regular Triangulation, from which a set of <span class="hlt">pores</span> connected by throats are identified. A local entry capillary <span class="hlt">pressure</span> is evaluated for each throat, based on the balance of capillary <span class="hlt">pressure</span> and surface tension at equilibrium. The model reflects the possible entrapment of disconnected patches of the receding wetting phase. It is validated by a comparison with drainage experiments. In the last part of the paper, a series of simulations are reported to illustrate size and boundary effects, key questions when studying small samples made of spherical particles be it in simulations or experiments. Repeated tests on samples of different sizes give evolution of water content which are not only scattered but also strongly biased for small sample sizes. More than 20,000 spheres are needed to reduce the bias on saturation below 0.02. Additional statistics are generated by subsampling a large sample of 64,000 spheres. They suggest that the minimal sampling volume for evaluating saturation is one hundred times greater that the sampling volume needed for measuring porosity with the same accuracy. This requirement in terms of sample size induces a need for efficient computer codes. The method described herein has a low algorithmic complexity in order to satisfy this requirement. It will be well suited to further developments toward coupled flow-deformation problems in which evolution of the</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017AGUFM.H13R..02J','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017AGUFM.H13R..02J"><span>Comparison of <span class="hlt">Pore</span>-scale CO2-water-glass System Wettability and Conventional Wettability Measurement on a Flat Plate for Geological CO2 Sequestration</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Jafari, M.; Cao, S. C.; Jung, J.</p> <p>2017-12-01</p> <p>Goelogical CO2 sequestration (GCS) has been recently introduced as an effective method to mitigate carbon dioxide emission. CO2 from main producer sources is collected and then is injected underground formations layers to be stored for thousands to millions years. A safe and economical storage project depends on having an insight of trapping mechanisms, fluids dynamics, and interaction of fluids-rocks. Among different forces governing fluids mobility and distribution in GCS condition, capillary <span class="hlt">pressure</span> is of importance, which, in turn, wettability (measured by contact angel (CA)) is the most controversial parameters affecting it. To explore the sources of discrepancy in the literature for CA measurement, we conducted a series of conventional captive bubble test on glass plates under high <span class="hlt">pressure</span> condition. By introducing a shape factor, we concluded that surface imperfection can distort the results in such tests. Since the conventional methods of measuring the CA is affected by gravity and scale effect, we introduced a different technique to measure <span class="hlt">pore</span>-scale CA inside a transparent glass microchip. Our method has the ability to consider <span class="hlt">pore</span> sizes and simulate static and dynamics CA during dewetting and imbibition. Glass plates shows a water-wet behavior (CA 30° - 45°) by a conventional experiment consistent with literature. However, CA of miniature bubbles inside of the micromodel can have a weaker water-wet behavior (CA 55° - 69°). In a more realistic <span class="hlt">pore</span>-scale condition, water- CO2 interface covers whole width of a <span class="hlt">pore</span> throats. Under this condition, the receding CA, which is used for injectability and capillary breakthrough <span class="hlt">pressure</span>, increases with decreasing <span class="hlt">pores</span> size. On the other hand, advancing CA, which is important for residual or capillary trapping, does not show a correlation with throat sizes. Static CA measured in the <span class="hlt">pores</span> during dewetting is lower than static CA on flat plate, but it is much higher when measured during imbibition implying</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016AdWR...98..198S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016AdWR...98..198S"><span>Construction of <span class="hlt">pore</span> network models for Berea and Fontainebleau sandstones using non-linear programing and optimization techniques</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Sharqawy, Mostafa H.</p> <p>2016-12-01</p> <p><span class="hlt">Pore</span> network models (PNM) of Berea and Fontainebleau sandstones were constructed using nonlinear programming (NLP) and optimization methods. The constructed PNMs are considered as a digital representation of the rock samples which were based on matching the macroscopic properties of the porous media and used to conduct fluid transport simulations including single and two-phase flow. The PNMs consisted of cubic networks of randomly distributed <span class="hlt">pores</span> and throats sizes and with various connectivity levels. The networks were optimized such that the upper and lower bounds of the <span class="hlt">pore</span> sizes are determined using the capillary tube bundle model and the Nelder-Mead method instead of guessing them, which reduces the optimization computational time significantly. An open-source PNM framework was employed to conduct transport and percolation simulations such as invasion percolation and Darcian flow. The PNM model was subsequently used to compute the macroscopic properties; porosity, absolute permeability, specific surface area, breakthrough capillary <span class="hlt">pressure</span>, and primary drainage curve. The <span class="hlt">pore</span> networks were optimized to allow for the simulation results of the macroscopic properties to be in excellent agreement with the experimental measurements. This study demonstrates that non-linear programming and optimization methods provide a promising method for <span class="hlt">pore</span> network modeling when computed tomography imaging may not be readily available.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19930054969&hterms=ultrasound&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D80%26Ntt%3Dultrasound','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19930054969&hterms=ultrasound&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D80%26Ntt%3Dultrasound"><span>Modeling the interaction of ultrasound with <span class="hlt">pores</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Lu, Yichi; Wadley, Haydn N. G.; Parthasarathi, Sanjai</p> <p>1991-01-01</p> <p>Factors that affect ultrasonic velocity sensing of density during consolidation of metal powders are examined. A comparison is made between experimental results obtained during the final stage of densification and the predictions of models that assume either a spherical or a spheroidal <span class="hlt">pore</span> shape. It is found that for measurements made at low frequencies during the final stage of densification, relative density (<span class="hlt">pore</span> fraction) and <span class="hlt">pore</span> shape are the two most important factors determining the ultrasonic velocity, the effect of <span class="hlt">pore</span> size is negligible.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011SolED...3..857F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011SolED...3..857F"><span><span class="hlt">Pore</span> formation during dehydration of polycrystalline gypsum observed and quantified in a time-series synchrotron radiation based X-ray micro-tomography experiment</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Fusseis, F.; Schrank, C.; Liu, J.; Karrech, A.; Llana-Fúnez, S.; Xiao, X.; Regenauer-Lieb, K.</p> <p>2011-10-01</p> <p>We conducted an in-situ X-ray micro-computed tomography heating experiment at the Advanced Photon Source (USA) to dehydrate an unconfined 2.3 mm diameter cylinder of Volterra Gypsum. We used a purpose-built X-ray transparent furnace to heat the sample to 388 K for a total of 310 min to acquire a three-dimensional time-series tomography dataset comprising nine time steps. The voxel size of 2.2 μm3 proved sufficient to pinpoint reaction initiation and the organization of drainage architecture in space and time. We observed that dehydration commences across a narrow front, which propagates from the margins to the centre of the sample in more than four hours. The advance of this front can be fitted with a square-root function, implying that the initiation of the reaction in the sample can be described as a diffusion process. Novel parallelized computer codes allow quantifying the geometry of the porosity and the drainage architecture from the very large tomographic datasets (6.4 × 109 voxel each) in unprecedented detail. We determined position, volume, shape and orientation of each resolvable <span class="hlt">pore</span> and tracked these properties over the duration of the experiment. We found that the <span class="hlt">pore</span>-size distribution follows a power law. <span class="hlt">Pores</span> tend to be anisotropic but rarely crack-shaped and have a preferred orientation, likely controlled by a pre-existing fabric in the sample. With on-going dehydration, <span class="hlt">pores</span> coalesce into a single interconnected <span class="hlt">pore</span> cluster that is connected to the surface of the sample cylinder and provides an effective drainage pathway. Our observations can be summarized in a model in which gypsum is stabilized by thermal expansion stresses and locally increased <span class="hlt">pore</span> fluid <span class="hlt">pressures</span> until the dehydration front approaches to within about 100 μm. Then, the internal stresses are released and dehydration happens efficiently, resulting in new <span class="hlt">pore</span> space. <span class="hlt">Pressure</span> release, the production of <span class="hlt">pores</span> and the advance of the front are coupled in a feedback loop. We</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li class="active"><span>19</span></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_19 --> <div id="page_20" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li class="active"><span>20</span></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="381"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012SolE....3...71F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012SolE....3...71F"><span><span class="hlt">Pore</span> formation during dehydration of a polycrystalline gypsum sample observed and quantified in a time-series synchrotron X-ray micro-tomography experiment</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Fusseis, F.; Schrank, C.; Liu, J.; Karrech, A.; Llana-Fúnez, S.; Xiao, X.; Regenauer-Lieb, K.</p> <p>2012-03-01</p> <p>We conducted an in-situ X-ray micro-computed tomography heating experiment at the Advanced Photon Source (USA) to dehydrate an unconfined 2.3 mm diameter cylinder of Volterra Gypsum. We used a purpose-built X-ray transparent furnace to heat the sample to 388 K for a total of 310 min to acquire a three-dimensional time-series tomography dataset comprising nine time steps. The voxel size of 2.2 μm3 proved sufficient to pinpoint reaction initiation and the organization of drainage architecture in space and time. We observed that dehydration commences across a narrow front, which propagates from the margins to the centre of the sample in more than four hours. The advance of this front can be fitted with a square-root function, implying that the initiation of the reaction in the sample can be described as a diffusion process. Novel parallelized computer codes allow quantifying the geometry of the porosity and the drainage architecture from the very large tomographic datasets (20483 voxels) in unprecedented detail. We determined position, volume, shape and orientation of each resolvable <span class="hlt">pore</span> and tracked these properties over the duration of the experiment. We found that the <span class="hlt">pore</span>-size distribution follows a power law. <span class="hlt">Pores</span> tend to be anisotropic but rarely crack-shaped and have a preferred orientation, likely controlled by a pre-existing fabric in the sample. With on-going dehydration, <span class="hlt">pores</span> coalesce into a single interconnected <span class="hlt">pore</span> cluster that is connected to the surface of the sample cylinder and provides an effective drainage pathway. Our observations can be summarized in a model in which gypsum is stabilized by thermal expansion stresses and locally increased <span class="hlt">pore</span> fluid <span class="hlt">pressures</span> until the dehydration front approaches to within about 100 μm. Then, the internal stresses are released and dehydration happens efficiently, resulting in new <span class="hlt">pore</span> space. <span class="hlt">Pressure</span> release, the production of <span class="hlt">pores</span> and the advance of the front are coupled in a feedback loop.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/pages/biblio/1433958-proton-diffusion-through-bilayer-pores','SCIGOV-DOEP'); return false;" href="https://www.osti.gov/pages/biblio/1433958-proton-diffusion-through-bilayer-pores"><span>Proton Diffusion through Bilayer <span class="hlt">Pores</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/pages">DOE PAGES</a></p> <p>McDaniel, Jesse G.; Yethiraj, Arun</p> <p>2017-09-26</p> <p>The transport of protons through channels in complex environments is important in biology and materials science. In this work, we use multistate empirical valence bond simulations to study proton transport within a well-defined bilayer <span class="hlt">pore</span> in a lamellar L β phase lyotropic liquid crystal (LLC). The LLC is formed from the self-assembly of dicarboxylate gemini surfactants in water, and a bilayer-spanning <span class="hlt">pore</span> of radius of approximately 3–5 Å results from the uneven partitioning of surfactants between the two leaflets of the lamella. Local proton diffusion within the <span class="hlt">pore</span> is significantly faster than diffusion at the bilayer surface, which is duemore » to the greater hydrophobicity of the surfactant/water interface within the <span class="hlt">pore</span>. Proton diffusion proceeds by surface transport along exposed hydrophobic pockets at the surfactant/water interface and depends on the continuity of hydronium–water hydrogen bond networks. At the bilayer surface, there is a reduced fraction of the “Zundel” intermediates that are central to the Grotthuss transport mechanism, whereas the fraction of these species within the bilayer <span class="hlt">pore</span> is similar to that in bulk water. Our results demonstrate that the chemical nature of the confining interface, in addition to confinement length scale, is an important determiner of local proton transport in nanoconfined aqueous environments.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/pages/biblio/1185987-precipitation-pores-geochemical-frontier','SCIGOV-DOEP'); return false;" href="https://www.osti.gov/pages/biblio/1185987-precipitation-pores-geochemical-frontier"><span>Precipitation in <span class="hlt">pores</span>: A geochemical frontier</span></a></p> <p><a target="_blank" href="http://www.osti.gov/pages">DOE PAGES</a></p> <p>Stack, Andrew G.</p> <p>2015-07-29</p> <p> velocities (Yoon et al. 2012). An improved ability to synthesize idealized porous media will allow for tailored control of <span class="hlt">pore</span> distributions, mineralogy and will allow more reproducible results. This in turn may allow us to isolate specific processes without the competing and obfuscatory effects that hinder generalization of observations when working with solely natural samples. It is likely that no one single experiment, or simulation technique will provide the key discoveries: to make substantive progress will require a collaborative effort to understand the interplay between fluid transport and geochemistry. Finally, where rock fracturing and elevated <span class="hlt">pressures</span> are of concern, an understanding and capability to model geomechanical properties are necessary (Scherer 1999).« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/27068885','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/27068885"><span>Clinical outcome and patient satisfaction using biodegradable (Naso<span class="hlt">Pore</span>) and non-biodegradable packing, a double-blind, prospective, randomized study.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Burduk, Pawel Krzysztof; Wierzchowska, Malgorzata; Grześkowiak, Blazej; Kaźmierczak, Wojciech; Wawrzyniak, Katarzyna</p> <p></p> <p>Nasal packing after endoscopic sinus surgery is used as a standard procedure. The optimum solution to minimize or eliminate all disadvantages of this procedure may be accomplished using biodegradable packs. The aim of this study was to compare patient satisfaction and clinical outcome associated with absorbable and non-absorbable packing after FESS. In total, 50 patients were included in a prospective, double-blind, randomized trial. One side was packed with polyurethane foam, while the opposite side was packed with gauze packing. On the 2nd, 10th, and 30th postoperative day, the patients were questioned with the aid of a visual analog scale. The standardized questionnaires for bleeding, nasal breathing, feeling of <span class="hlt">pressure</span>, and headache were used. The presence of synechiae, infection, or granulation was noted and recorded with the video-endoscopy. A significant difference according to lower <span class="hlt">pressure</span> was found in the Naso<span class="hlt">Pore</span> group compared to the controls on day ten after surgery. The Naso<span class="hlt">Pore</span> packing had lower scores with respect to postoperative nose blockage on the 2nd and 10th days. Mucosal healing was better for the Naso<span class="hlt">Pore</span> group, both at day ten and 30 compared with the control group. The overall patient comfort is higher when using Naso<span class="hlt">Pore</span> compared to non-resorbable traditional impregnated gauze packing. Intensive saline douches applied three to four times per day are mandatory after the operation to prevent synechiae formation and fluid resorption by the packing. Published by Elsevier Editora Ltda.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014AGUFM.H53A0835M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014AGUFM.H53A0835M"><span>Dynamic <span class="hlt">Pore</span>-Scale Imaging of Reactive Transport in Heterogeneous Carbonates at Reservoir Conditions Across Multiple Dissolution Regimes</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Menke, H. P.; Bijeljic, B.; Andrew, M. G.; Blunt, M. J.</p> <p>2014-12-01</p> <p>Sequestering carbon in deep geologic formations is one way of reducing anthropogenic CO2 emissions. When supercritical CO2 mixes with brine in a reservoir, the acid generated has the potential to dissolve the surrounding <span class="hlt">pore</span> structure. However, the magnitude and type of dissolution are condition dependent. Understanding how small changes in the <span class="hlt">pore</span> structure, chemistry, and flow properties affect dissolution is paramount for successful predictive modelling. Both 'Pink Beam' synchrotron radiation and a Micro-CT lab source are used in dynamic X-ray microtomography to investigate the <span class="hlt">pore</span> structure changes during supercritical CO2 injection in carbonate rocks of varying heterogeneity at high temperatures and <span class="hlt">pressures</span> and various flow-rates. Three carbonate rock types were studied, one with a homogeneous <span class="hlt">pore</span> structure and two heterogeneous carbonates. All samples are practically pure calcium carbonate, but have widely varying rock structures. Flow-rate was varied in three successive experiments by over an order of magnitude whlie keeping all other experimental conditions constant. A 4-mm carbonate core was injected with CO2-saturated brine at 10 MPa and 50oC. Tomographic images were taken at 30-second to 20-minute time-resolutions during a 2 to 4-hour injection period. A <span class="hlt">pore</span> network was extracted using a topological analysis of the <span class="hlt">pore</span> space and <span class="hlt">pore</span>-scale flow modelling was performed directly on the binarized images with connected pathways and used to track the altering velocity distributions. Significant differences in dissolution type and magnitude were found for each rock type and flowrate. At the highest flow-rates, the homogeneous carbonate was seen to have predominately uniform dissolution with minor dissolution rate differences between the <span class="hlt">pores</span> and <span class="hlt">pore</span> throats. Alternatively, the heterogeneous carbonates which formed wormholes at high flow rates. At low flow rates the homogeneous rock developed wormholes, while the heterogeneous samples showed evidence</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19970014147','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19970014147"><span>Performance of Small <span class="hlt">Pore</span> Microchannel Plates</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Siegmund, O. H. W.; Gummin, M. A.; Ravinett, T.; Jelinsky, S. R.; Edgar, M.</p> <p>1995-01-01</p> <p>Small <span class="hlt">pore</span> size microchannel plates (MCP's) are needed to satisfy the requirements for future high resolution small and large format detectors for astronomy. MCP's with <span class="hlt">pore</span> sizes in the range 5 micron to 8 micron are now being manufactured, but they are of limited availability and are of small size. We have obtained sets of Galileo 8 micron and 6.5 micron MCP's, and Philips 6 micron and 7 micron <span class="hlt">pore</span> MCP's, and compared them to our larger <span class="hlt">pore</span> MCP Z stacks. We have tested back to back MCP stacks of four of these MCP's and achieved gains greater than 2 x 1O(exp 7) with pulse height distributions of less than 40% FWHM, and background rates of less than 0.3 events sec(exp -1) cm(exp -2). Local counting rates up to approx. 100 events/<span class="hlt">pore</span>/sec have been attained with little drop of the MCP gain. The bare MCP quantum efficiencies are somewhat lower than those expected, however. Flat field images are characterized by an absence of MCP fixed pattern noise.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/biblio/655506-fischer-tropsch-synthesis-near-critical-hexane-pressure-tuning-effects','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/655506-fischer-tropsch-synthesis-near-critical-hexane-pressure-tuning-effects"><span>Fischer-Tropsch synthesis in near-critical n-hexane: <span class="hlt">Pressure</span>-tuning effects</span></a></p> <p><a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a></p> <p>Bochniak, D.J.; Subramaniam, B.</p> <p></p> <p>For Fe-catalyzed Fischer-Tropsch (FT) synthesis with near-critical n-hexane (P{sub c} = 29.7 bar; T{sub c} = 233.7 C) as the reaction medium, isothermal <span class="hlt">pressure</span> tuning from 1.2--2.4 P{sub c} (for n-hexane) at the reaction temperature (240 C) significantly changes syngas conversion and product selectivity. For fixed feed rates of syngas (H{sub 2}/CO = 0.5; 50 std. cm{sup 3}/g catalyst) and n-hexane (1 mL/min), syngas conversion attains a steady state at all <span class="hlt">pressures</span>, increasing roughly threefold in this <span class="hlt">pressure</span> range. Effective rate constants, estimated assuming a first-order dependence of syngas conversion on hydrogen, reveal that the catalyst effectiveness increases with pressuremore » implying the alleviation of <span class="hlt">pore</span>-diffusion limitations. <span class="hlt">Pore</span> accessibilities increase at higher <span class="hlt">pressures</span> because the extraction of heavier hydrocarbons from the catalyst <span class="hlt">pores</span> is enhanced by the liquid-like densities, yet better-than-liquid transport properties, of n-hexane. This explanation is consistent with the single {alpha} (= 0.78) Anderson-Schulz-Flory product distribution, the constant chain termination probability, and the higher primary product (1-olefin) selectivities ({approximately}80%) observed at the higher <span class="hlt">pressures</span>. Results indicate that the <span class="hlt">pressure</span> tunability of the density and transport properties of near-critical reaction media offers a powerful tool to optimize catalyst activity and product selectivity during FT reactions on supported catalysts.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017PhRvE..96b3307G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017PhRvE..96b3307G"><span>Versatile and efficient <span class="hlt">pore</span> network extraction method using marker-based watershed segmentation</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Gostick, Jeff T.</p> <p>2017-08-01</p> <p>Obtaining structural information from tomographic images of porous materials is a critical component of porous media research. Extracting <span class="hlt">pore</span> networks is particularly valuable since it enables <span class="hlt">pore</span> network modeling simulations which can be useful for a host of tasks from predicting transport properties to simulating performance of entire devices. This work reports an efficient algorithm for extracting networks using only standard image analysis techniques. The algorithm was applied to several standard porous materials ranging from sandstone to fibrous mats, and in all cases agreed very well with established or known values for <span class="hlt">pore</span> and throat sizes, capillary <span class="hlt">pressure</span> curves, and permeability. In the case of sandstone, the present algorithm was compared to the network obtained using the current state-of-the-art algorithm, and very good agreement was achieved. Most importantly, the network extracted from an image of fibrous media correctly predicted the anisotropic permeability tensor, demonstrating the critical ability to detect key structural features. The highly efficient algorithm allows extraction on fairly large images of 5003 voxels in just over 200 s. The ability for one algorithm to match materials as varied as sandstone with 20% porosity and fibrous media with 75% porosity is a significant advancement. The source code for this algorithm is provided.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018PSST...27c5009Z','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018PSST...27c5009Z"><span>Propagation of a plasma streamer in catalyst <span class="hlt">pores</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Zhang, Quan-Zhi; Bogaerts, Annemie</p> <p>2018-03-01</p> <p>Although plasma catalysis is gaining increasing interest for various environmental applications, the underlying mechanisms are still far from understood. For instance, it is not yet clear whether and how plasma streamers can propagate in catalyst <span class="hlt">pores</span>, and what is the minimum <span class="hlt">pore</span> size to make this happen. As this is crucial information to ensure good plasma-catalyst interaction, we study here the mechanism of plasma streamer propagation in a catalyst <span class="hlt">pore</span>, by means of a two-dimensional particle-in-cell/Monte Carlo collision model, for various <span class="hlt">pore</span> diameters in the nm-range to μm-range. The so-called Debye length is an important criterion for plasma penetration into catalyst <span class="hlt">pores</span>, i.e. a plasma streamer can penetrate into <span class="hlt">pores</span> when their diameter is larger than the Debye length. The Debye length is typically in the order of a few 100 nm up to 1 μm at the conditions under study, depending on electron density and temperature in the plasma streamer. For <span class="hlt">pores</span> in the range of ∼50 nm, plasma can thus only penetrate to some extent and at very short times, i.e. at the beginning of a micro-discharge, before the actual plasma streamer reaches the catalyst surface and a sheath is formed in front of the surface. We can make plasma streamers penetrate into smaller <span class="hlt">pores</span> (down to ca. 500 nm at the conditions under study) by increasing the applied voltage, which yields a higher plasma density, and thus reduces the Debye length. Our simulations also reveal that the plasma streamers induce surface charging of the catalyst <span class="hlt">pore</span> sidewalls, causing discharge enhancement inside the <span class="hlt">pore</span>, depending on <span class="hlt">pore</span> diameter and depth.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/21469216','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/21469216"><span>An emerging <span class="hlt">pore</span>-making strategy: confined swelling-induced <span class="hlt">pore</span> generation in block copolymer materials.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Wang, Yong; Li, Fengbin</p> <p>2011-05-17</p> <p>Block copolymers (BCPs) composed of two or more thermodynamically incompatible homopolymers self-assemble into periodic microdomains. Exposing self-assembled BCPs with solvents selective to one block causes a swelling of the domains composed of this block. Strong swelling in the confinement imposed by the matrix of the other glassy block leads to well-defined porous structures via morphology reconstruction. This confined swelling-induced <span class="hlt">pore</span>-making process has emerged recently as a new strategy to produce porous materials due to synergic advantages that include extreme simplicity, high <span class="hlt">pore</span> regularity, involvement of no chemical reactions, no weight loss, reversibility of the <span class="hlt">pore</span> forming process, etc. The mechanism, kinetics, morphology, and governing parameters of the confined swelling-induced <span class="hlt">pore</span>-making process in BCP thin films are discussed, and the main applications of nanoporous thin films in the fields of template synthesis, surface patterning, and guidance for the areal arrangements of nanomaterials and biomolecules are summarized. Recent, promising results of extending this mechanism to produce BCP nanofibers or nanotubes and bulk materials with well-defined porosity, which makes this strategy also attractive to researchers outside the nanocommunity, are also presented. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/biblio/1057875-application-real-rock-pore-threat-statistics-regular-pore-network-model','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/1057875-application-real-rock-pore-threat-statistics-regular-pore-network-model"><span>Application of real rock <span class="hlt">pore</span>-threat statistics to a regular <span class="hlt">pore</span> network model</span></a></p> <p><a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a></p> <p>Rakibul, M.; Sarker, H.; McIntyre, D.</p> <p>2011-01-01</p> <p>This work reports the application of real rock statistical data to a previously developed regular <span class="hlt">pore</span> network model in an attempt to produce an accurate simulation tool with low computational overhead. A core plug from the St. Peter Sandstone formation in Indiana was scanned with a high resolution micro CT scanner. The <span class="hlt">pore</span>-throat statistics of the three-dimensional reconstructed rock were extracted and the distribution of the <span class="hlt">pore</span>-throat sizes was applied to the regular <span class="hlt">pore</span> network model. In order to keep the equivalent model regular, only the throat area or the throat radius was varied. Ten realizations of randomly distributed throatmore » sizes were generated to simulate the drainage process and relative permeability was calculated and compared with the experimentally determined values of the original rock sample. The numerical and experimental procedures are explained in detail and the performance of the model in relation to the experimental data is discussed and analyzed. Petrophysical properties such as relative permeability are important in many applied fields such as production of petroleum fluids, enhanced oil recovery, carbon dioxide sequestration, ground water flow, etc. Relative permeability data are used for a wide range of conventional reservoir engineering calculations and in numerical reservoir simulation. Two-phase oil water relative permeability data are generated on the same core plug from both <span class="hlt">pore</span> network model and experimental procedure. The shape and size of the relative permeability curves were compared and analyzed and good match has been observed for wetting phase relative permeability but for non-wetting phase, simulation results were found to be deviated from the experimental ones. Efforts to determine petrophysical properties of rocks using numerical techniques are to eliminate the necessity of regular core analysis, which can be time consuming and expensive. So a numerical technique is expected to be fast and to produce reliable</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/biblio/1062712-application-real-rock-pore-throat-statistics-regular-pore-network-model','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/1062712-application-real-rock-pore-throat-statistics-regular-pore-network-model"><span>Application of real rock <span class="hlt">pore</span>-throat statistics to a regular <span class="hlt">pore</span> network model</span></a></p> <p><a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a></p> <p>Sarker, M.R.; McIntyre, D.; Ferer, M.</p> <p>2011-01-01</p> <p>This work reports the application of real rock statistical data to a previously developed regular <span class="hlt">pore</span> network model in an attempt to produce an accurate simulation tool with low computational overhead. A core plug from the St. Peter Sandstone formation in Indiana was scanned with a high resolution micro CT scanner. The <span class="hlt">pore</span>-throat statistics of the three-dimensional reconstructed rock were extracted and the distribution of the <span class="hlt">pore</span>-throat sizes was applied to the regular <span class="hlt">pore</span> network model. In order to keep the equivalent model regular, only the throat area or the throat radius was varied. Ten realizations of randomly distributed throatmore » sizes were generated to simulate the drainage process and relative permeability was calculated and compared with the experimentally determined values of the original rock sample. The numerical and experimental procedures are explained in detail and the performance of the model in relation to the experimental data is discussed and analyzed. Petrophysical properties such as relative permeability are important in many applied fields such as production of petroleum fluids, enhanced oil recovery, carbon dioxide sequestration, ground water flow, etc. Relative permeability data are used for a wide range of conventional reservoir engineering calculations and in numerical reservoir simulation. Two-phase oil water relative permeability data are generated on the same core plug from both <span class="hlt">pore</span> network model and experimental procedure. The shape and size of the relative permeability curves were compared and analyzed and good match has been observed for wetting phase relative permeability but for non-wetting phase, simulation results were found to be deviated from the experimental ones. Efforts to determine petrophysical properties of rocks using numerical techniques are to eliminate the necessity of regular core analysis, which can be time consuming and expensive. So a numerical technique is expected to be fast and to produce reliable</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018JGRB..123.1089F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018JGRB..123.1089F"><span><span class="hlt">Pressure</span> and Stress Prediction in the Nankai Accretionary Prism: A Critical State Soil Mechanics Porosity-Based Approach</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Flemings, Peter B.; Saffer, Demian M.</p> <p>2018-02-01</p> <p>We predict <span class="hlt">pressure</span> and stress from porosity in the Nankai accretionary prism with a critical state soil model that describes porosity as a function of mean stress and maximum shear stress, and assumes Coulomb failure within the wedge and uniaxial burial beneath it. At Ocean Drilling Program Sites 1174 and 808, we find that <span class="hlt">pore</span> <span class="hlt">pressure</span> in the prism supports 70% to 90% of the overburden (λu = 0.7 to 0.9), for a range of assumed friction angles (5-30°). The prism <span class="hlt">pore</span> <span class="hlt">pressure</span> is equal to or greater than that in the underthrust sediments even though the porosity is lower within the prism. The high <span class="hlt">pore</span> <span class="hlt">pressures</span> lead to a mechanically weak wedge that supports low maximum shear stress, and this in turn requires very low basal traction to remain consistent with the observed narrowly tapered wedge geometry. We estimate the décollement friction coefficient (μb) to be 0.08-0.38 (ϕb' = 4.6°-21°). Our approach defines a pathway to predict <span class="hlt">pressure</span> in a wide range of environments from readily observed quantities (e.g., porosity and seismic velocity). <span class="hlt">Pressure</span> and stress control the form of the Earth's collisional continental margins and play a key role in its greatest earthquakes. However, heretofore, there has been no systematic approach to relate material state (e.g., porosity), <span class="hlt">pore</span> <span class="hlt">pressure</span>, and stress in these systems.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/pages/biblio/1389557-quantifying-similarity-pore-geometry-nanoporous-materials','SCIGOV-DOEP'); return false;" href="https://www.osti.gov/pages/biblio/1389557-quantifying-similarity-pore-geometry-nanoporous-materials"><span>Quantifying similarity of <span class="hlt">pore</span>-geometry in nanoporous materials</span></a></p> <p><a target="_blank" href="http://www.osti.gov/pages">DOE PAGES</a></p> <p>Lee, Yongjin; Barthel, Senja D.; Dłotko, Paweł; ...</p> <p>2017-05-23</p> <p>In most applications of nanoporous materials the <span class="hlt">pore</span> structure is as important as the chemical composition as a determinant of performance. For example, one can alter performance in applications like carbon capture or methane storage by orders of magnitude by only modifying the <span class="hlt">pore</span> structure. For these applications it is therefore important to identify the optimal <span class="hlt">pore</span> geometry and use this information to find similar materials. But, the mathematical language and tools to identify materials with similar <span class="hlt">pore</span> structures, but different composition, has been lacking. We develop a <span class="hlt">pore</span> recognition approach to quantify similarity of <span class="hlt">pore</span> structures and classify themmore » using topological data analysis. This then allows us to identify materials with similar <span class="hlt">pore</span> geometries, and to screen for materials that are similar to given top-performing structures. Using methane storage as a case study, we also show that materials can be divided into topologically distinct classes requiring different optimization strategies.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017JTST...26.1183Z','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017JTST...26.1183Z"><span>Multiscale <span class="hlt">Pores</span> in TBCs for Lower Thermal Conductivity</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Zhang, Wei-Wei; Li, Guang-Rong; Zhang, Qiang; Yang, Guan-Jun</p> <p>2017-08-01</p> <p>The morphology and pattern (including orientation and aspect ratio) of <span class="hlt">pores</span> in thermal barrier coatings (TBCs) significantly affect their thermal insulation performance. In this work, finite element analysis was used to comprehensively understand the thermal insulation effect of <span class="hlt">pores</span> and correlate the effective thermal conductivity with the structure. The results indicated that intersplat <span class="hlt">pores</span>, and in particular their aspect ratio, dominantly affect the heat transfer in the top coat. The effective thermal conductivity decreased as a function of aspect ratio, since a larger aspect ratio often corresponds to a greater proportion of effective length of the <span class="hlt">pores</span>. However, in conventional plasma-sprayed TBCs, intersplat <span class="hlt">pores</span> often fail to maximize thermal insulation due to their distinct lower aspect ratios. Therefore, considering this effect of aspect ratio, a new structure design with multiscale <span class="hlt">pores</span> is proposed and a corresponding structural model developed to correlate the thermal properties with this <span class="hlt">pore</span>-rich structure. The predictions of the model are well consistent with experimental data. This study provides comprehensive understanding of the effect of <span class="hlt">pores</span> on the thermal insulation performance, shedding light on the possibility of structural tailoring to obtain advanced TBCs with lower thermal conductivity.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/29740064','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/29740064"><span>Tortuous <span class="hlt">Pore</span> Path Through the Glaucomatous Lamina Cribrosa.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Wang, Bo; Lucy, Katie A; Schuman, Joel S; Sigal, Ian A; Bilonick, Richard A; Lu, Chen; Liu, Jonathan; Grulkowski, Ireneusz; Nadler, Zachary; Ishikawa, Hiroshi; Kagemann, Larry; Fujimoto, James G; Wollstein, Gadi</p> <p>2018-05-08</p> <p>The lamina cribrosa is a primary site of damage in glaucoma. While mechanical distortion is hypothesized to cause reduction of axoplasmic flow, little is known about how the <span class="hlt">pores</span>, which contains the retinal ganglion cell axons, traverse the lamina cribrosa. We investigated lamina cribrosa <span class="hlt">pore</span> paths in vivo to quantify differences in tortuosity of <span class="hlt">pore</span> paths between healthy and glaucomatous eyes. We imaged 16 healthy, 23 glaucoma suspect and 48 glaucomatous eyes from 70 subjects using a swept source optical coherence tomography system. The lamina cribrosa <span class="hlt">pores</span> were automatically segmented using a previously described segmentation algorithm. Individual <span class="hlt">pore</span> paths were automatically tracked through the depth of the lamina cribrosa using custom software. <span class="hlt">Pore</span> path convergence to the optic nerve center and tortuosity was quantified for each eye. We found that lamina cribrosa <span class="hlt">pore</span> pathways traverse the lamina cribrosa closer to the optic nerve center along the depth of the lamina cribrosa regardless of disease severity or diagnostic category. In addition, <span class="hlt">pores</span> of glaucoma eyes take a more tortuous path through the lamina cribrosa compared to those of healthy eyes, suggesting a potential mechanism for reduction of axoplasmic flow in glaucoma.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018MRE.....5b6506H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018MRE.....5b6506H"><span>Experimental study on <span class="hlt">pore</span> structure and performance of sintered porous wick</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>He, Da; Wang, Shufan; Liu, Rutie; Wang, Zhubo; Xiong, Xiang; Zou, Jianpeng</p> <p>2018-02-01</p> <p>Porous wicks were prepared via powder metallurgy using NH4HCO3 powders as <span class="hlt">pore</span>-forming agent. The <span class="hlt">pore</span>-forming agent particle size was varied to control the <span class="hlt">pore</span> structure and equivalent <span class="hlt">pore</span> size distribution feature of porous wick. The effect of <span class="hlt">pore</span>-forming agent particle size on the porosity, <span class="hlt">pore</span> structures, equivalent <span class="hlt">pore</span> size distribution and capillary pumping performance were investigated. Results show that with the particle size of <span class="hlt">pore</span>-forming agent decrease, the green density and the volume shrinkage of the porous wicks gradually increase and the porosity reduces slightly. There are two types of <span class="hlt">pores</span> inside the porous wick, large-sized prefabricated <span class="hlt">pores</span> and small-sized gap <span class="hlt">pores</span>. With the particle size of <span class="hlt">pore</span>-forming agent decrease, the size of the prefabricated <span class="hlt">pores</span> becomes smaller and the distribution tends to be uniform. Gap <span class="hlt">pores</span> and prefabricated <span class="hlt">pores</span> inside the wick can make up different types of <span class="hlt">pore</span> channels. The equivalent <span class="hlt">pore</span> size of wick is closely related to the structure of <span class="hlt">pore</span> channels. Furthermore, the equivalent <span class="hlt">pore</span> size distribution of wick shows an obvious double-peak feature when the <span class="hlt">pore</span>-forming agent particle size is large. With the particle size of <span class="hlt">pore</span>-forming agent decrease, the two peaks of equivalent <span class="hlt">pore</span> size distribution approach gradually to each other, resulting in a single-peak feature. Porous wick with single-peak feature equivalent <span class="hlt">pore</span> size distribution possesses the better capillary pumping performances.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/29652115','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/29652115"><span>Analysis on influencing factors of <span class="hlt">abnormal</span> renal function in elderly patients with type 2 diabetes mellitus.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Chai, Tao; Zhang, Dawei; Li, Zhongxin</p> <p>2018-04-12</p> <p>To investigate the related influencing factors of <span class="hlt">abnormal</span> renal function in elderly in patients with type 2 diabetes mellitus (T2DM) and their clinical significance. The clinical data of elderly T2DM patients hospitalized in Beijing Luhe Hospital from January 2013 to June2016 were retrospectively analyzed. According to their glomerular filtration rate (GFR) levels, these patients were divided into GFR ≥90 mL/min/1.73m2 group (Group A), GFR =60-90 mL/min/1.73m2 group (Group B), and GFR <60 mL/min/1.73m2 group (Group C, i.e., <span class="hlt">abnormal</span> renal function group). Clinical and laboratory indicators were compared among each group. A total of 614 elderly T2DM patients were collected and divided into Group A (n=186), Group B (n=280) and Group C (n=148, 24.10%). Among them, patients clinically diagnosed with diabetic nephropathy (DN) accounted for 13.68%, and those complicated with high blood <span class="hlt">pressure</span> (HBP) accounted for 61.40%. In Group C, DN accounted for only 29.73%. In elderly T2DM patients, HBP course, systolic blood <span class="hlt">pressure</span> (SBP), diastolic blood <span class="hlt">pressure</span> (DBP), 2h postprandial blood glucose (2hPBG), serum total cholesterol (TC) and blood uric acid (BUA) were independent influencing factors associated with <span class="hlt">abnormal</span> renal function, among which HBP had a more significant impact on <span class="hlt">abnormal</span> renal function. With the increase of blood <span class="hlt">pressure</span> (BP) level, the extension in the course of DM, the increase in urinary albumin/creatinine (Alb/Cr) and the decrease in GFR, the incidence rate of <span class="hlt">abnormal</span> renal function was increased. HBP course, SBP, DBP, 2hPBG, TC and BUA are independent risk factors for <span class="hlt">abnormal</span> renal function in elderly patients with T2DM. Well-controlled BP and blood glucose are protective factors, and a comprehensive treatment targeting to the above influencing factors has important clinical significance in preventing and delaying the occurrence and development of <span class="hlt">abnormal</span> renal function.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014AGUFM.H51C0623D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014AGUFM.H51C0623D"><span>A Model for Hydraulic Properties Based on Angular <span class="hlt">Pores</span> with Lognormal Size Distribution</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Durner, W.; Diamantopoulos, E.</p> <p>2014-12-01</p> <p>Soil water retention and unsaturated hydraulic conductivity curves are mandatory for modeling water flow in soils. It is a common approach to measure few points of the water retention curve and to calculate the hydraulic conductivity curve by assuming that the soil can be represented as a bundle of capillary tubes. Both curves are then used to predict water flow at larger spatial scales. However, the predictive power of these curves is often very limited. This can be very easily illustrated if we measure the soil hydraulic properties (SHPs) for a drainage experiment and then use these properties to predict the water flow in the case of imbibition. Further complications arise from the incomplete wetting of water at the solid matrix which results in finite values of the contact angles between the solid-water-air interfaces. To address these problems we present a physically-based model for hysteretic SHPs. This model is based on bundles of angular <span class="hlt">pores</span>. Hysteresis for individual <span class="hlt">pores</span> is caused by (i) different snap-off <span class="hlt">pressures</span> during filling and emptying of single angular <span class="hlt">pores</span> and (ii) by different advancing and receding contact angles for fluids that are not perfectly wettable. We derive a model of hydraulic conductivity as a function of contact angle by assuming flow perpendicular to <span class="hlt">pore</span> cross sections and present closed-form expressions for both the sample scale water retention and hydraulic conductivity function by assuming a log-normal statistical distribution of <span class="hlt">pore</span> size. We tested the new model against drainage and imbibition experiments for various sandy materials which were conducted with various liquids of differing wettability. The model described both imbibition and drainage experiments very well by assuming a unique <span class="hlt">pore</span> size distribution of the sample and a zero contact angle for the perfectly wetting liquid. Eventually, we see the possibility to relate the particle size distribution with a model which describes the SHPs.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018PSST...27e5008Z','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018PSST...27e5008Z"><span>Enhancement of plasma generation in catalyst <span class="hlt">pores</span> with different shapes</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Zhang, Yu-Ru; Neyts, Erik C.; Bogaerts, Annemie</p> <p>2018-05-01</p> <p>Plasma generation inside catalyst <span class="hlt">pores</span> is of utmost importance for plasma catalysis, as the existence of plasma species inside the <span class="hlt">pores</span> affects the active surface area of the catalyst available to the plasma species for catalytic reactions. In this paper, the electric field enhancement, and thus the plasma production inside catalyst <span class="hlt">pores</span> with different <span class="hlt">pore</span> shapes is studied with a two-dimensional fluid model. The results indicate that the electric field will be significantly enhanced near tip-like structures. In a conical <span class="hlt">pore</span> with small opening, the strongest electric field appears at the opening and bottom corners of the <span class="hlt">pore</span>, giving rise to a prominent ionization rate throughout the <span class="hlt">pore</span>. For a cylindrical <span class="hlt">pore</span>, the electric field is only enhanced at the bottom corners of the <span class="hlt">pore</span>, with lower absolute value, and thus the ionization rate inside the <span class="hlt">pore</span> is only slightly enhanced. Finally, in a conical <span class="hlt">pore</span> with large opening, the electric field is characterized by a maximum at the bottom of the <span class="hlt">pore</span>, yielding a similar behavior for the ionization rate. These results demonstrate that the shape of the <span class="hlt">pore</span> has a significantly influence on the electric field enhancement, and thus modifies the plasma properties.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li class="active"><span>20</span></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_20 --> <div id="page_21" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li class="active"><span>21</span></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="401"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017EGUGA..19.9838D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017EGUGA..19.9838D"><span>Multiscale <span class="hlt">pore</span> networks and their effect on deformation and transport property alteration associated with hydraulic fracturing</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Daigle, Hugh; Hayman, Nicholas; Jiang, Han; Tian, Xiao; Jiang, Chunbi</p> <p>2017-04-01</p> <p>Multiple lines of evidence indicate that, during a hydraulic fracture stimulation, the permeability of the unfractured matrix far from the main, induced tensile fracture increases by one to two orders of magnitude. This permeability enhancement is associated with pervasive shear failure in a large region surrounding the main induced fracture. We have performed low-<span class="hlt">pressure</span> gas sorption, mercury intrusion, and nuclear magnetic resonance measurements along with high-resolution scanning electron microscope imaging on several preserved and unpreserved shale samples from North American basins before and after inducing failure in confined compressive strength tests. We have observed that the <span class="hlt">pore</span> structure in intact samples exhibits multiscale behavior, with sub-micron-scale <span class="hlt">pores</span> in organic matter connected in isolated, micron-scale clusters which themselves are connected to each other through a network of microcracks. The organic-hosted <span class="hlt">pore</span> networks are poorly connected due to a significant number of dead-end <span class="hlt">pores</span> within the organic matter. Following shear failure, we often observe an increase in <span class="hlt">pore</span> volume in the sub-micron range, which appears to be related to the formation of microcracks that propagate along grain boundaries and other planes of mechanical strength contrast. This is consistent with other experimental and field evidence. In some cases these microcracks cross or terminate in organic matter, intersecting the organic-hosted <span class="hlt">pores</span>. The induced microcrack networks typically have low connectivity and do not appreciably increase the connectivity of the overall <span class="hlt">pore</span> network. However, in other cases the shear deformation results in an overall <span class="hlt">pore</span> volume decrease; samples which exhibit this behavior tend to have more clay minerals. Our interpretation of these phenomena is as follows. As organic matter is converted to hydrocarbons, organic-hosted <span class="hlt">pores</span> develop, and the hydrocarbons contained in these <span class="hlt">pores</span> are overpressured. The disconnected nature of these</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/24824167','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/24824167"><span>Anisotropy estimation of compacted municipal solid waste using <span class="hlt">pressurized</span> vertical well liquids injection.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Singh, Karamjit; Kadambala, Ravi; Jain, Pradeep; Xu, Qiyong; Townsend, Timothy G</p> <p>2014-06-01</p> <p>Waste hydraulic conductivity and anisotropy represent two important parameters controlling fluid movement in landfills, and thus are the key inputs in design methods where predictions of moisture movement are necessary. Although municipal waste hydraulic conductivity has been estimated in multiple laboratory and field studies, measurements of anisotropy, particularly at full scale, are rare, even though landfilled municipal waste is generally understood to be anisotropic. Measurements from a buried liquids injection well surrounded by <span class="hlt">pressure</span> transducers at a full-scale landfill in Florida were collected and examined to provide an estimate of in-situ waste anisotropy. Liquids injection was performed at a constant <span class="hlt">pressure</span> and the resulting <span class="hlt">pore</span> <span class="hlt">pressures</span> in the surrounding waste were monitored. Numerical fluid flow modeling was employed to simulate the <span class="hlt">pore</span> <span class="hlt">pressures</span> expected to occur under the conditions operated. Nine different simulations were performed at three different lateral hydraulic conductivity values and three different anisotropy values. Measured flowrate and <span class="hlt">pore</span> <span class="hlt">pressures</span> collected from conditions of approximate steady state were compared with the simulation results to assess the range of anisotropies. The results support that compacted municipal waste in landfills is anisotropic, provide anisotropy estimates greater than previous measurements, and suggest that anisotropy decreases with landfill depth. © The Author(s) 2014.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/22736839','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/22736839"><span>Partitioning of habitable <span class="hlt">pore</span> space in earthworm burrows.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Gorres, Josef H; Amador, Jose A</p> <p>2010-03-01</p> <p>Earthworms affect macro-<span class="hlt">pore</span> structure of soils. However, some studies suggest that earthworm burrow walls and casts themselves differ greatly in structure from surrounding soils, potentially creating habitat for microbivorours nematodes which accelerate the decomposition and C and N mineralization. In this study aggregates were sampled from the burrow walls of the anecic earthworm Lumbricus terrestris and bulk soil (not altered by earthworms) from mesocosm incubated in the lab for 0, 1, 3, 5 and 16 weeks. <span class="hlt">Pore</span> volumes and <span class="hlt">pore</span> sizes were measured in triplicate with Mercury Intrusion Porosimetry (MIP). This method is well suited to establish <span class="hlt">pore</span> size structure in the context of habitat, because it measures the stepwise intrusion of mercury from the outside of the aggregate into ever smaller <span class="hlt">pores</span>. The progress of mercury into the aggregate interior thus resembles potential paths of a nematode into accessible habitable <span class="hlt">pore</span> spaces residing in an aggregate. Total specific <span class="hlt">pore</span> volume, V(s), varied between 0.13 and 0.18 mL/g and increased from 3 to 16 weeks in both burrow and bulk soil. Differences between total V(s) of bulk and burrow samples were not significant on any sampling date. However, differences were significant for <span class="hlt">pore</span> size fractions at the scale of nematode body diameter.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3380515','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3380515"><span>Partitioning of habitable <span class="hlt">pore</span> space in earthworm burrows</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Amador, Jose A.</p> <p>2010-01-01</p> <p>Earthworms affect macro-<span class="hlt">pore</span> structure of soils. However, some studies suggest that earthworm burrow walls and casts themselves differ greatly in structure from surrounding soils, potentially creating habitat for microbivorours nematodes which accelerate the decomposition and C and N mineralization. In this study aggregates were sampled from the burrow walls of the anecic earthworm Lumbricus terrestris and bulk soil (not altered by earthworms) from mesocosm incubated in the lab for 0, 1, 3, 5 and 16 weeks. <span class="hlt">Pore</span> volumes and <span class="hlt">pore</span> sizes were measured in triplicate with Mercury Intrusion Porosimetry (MIP). This method is well suited to establish <span class="hlt">pore</span> size structure in the context of habitat, because it measures the stepwise intrusion of mercury from the outside of the aggregate into ever smaller <span class="hlt">pores</span>. The progress of mercury into the aggregate interior thus resembles potential paths of a nematode into accessible habitable <span class="hlt">pore</span> spaces residing in an aggregate. Total specific <span class="hlt">pore</span> volume, Vs, varied between 0.13 and 0.18 mL/g and increased from 3 to 16 weeks in both burrow and bulk soil. Differences between total Vs of bulk and burrow samples were not significant on any sampling date. However, differences were significant for <span class="hlt">pore</span> size fractions at the scale of nematode body diameter. PMID:22736839</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5287468','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5287468"><span>Nuclear <span class="hlt">Pore</span>-Like Structures in a Compartmentalized Bacterium</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Sagulenko, Evgeny; Green, Kathryn; Yee, Benjamin; Morgan, Garry; Leis, Andrew; Lee, Kuo-Chang; Butler, Margaret K.; Chia, Nicholas; Pham, Uyen Thi Phuong; Lindgreen, Stinus; Catchpole, Ryan; Poole, Anthony M.; Fuerst, John A.</p> <p>2017-01-01</p> <p>Planctomycetes are distinguished from other Bacteria by compartmentalization of cells via internal membranes, interpretation of which has been subject to recent debate regarding potential relations to Gram-negative cell structure. In our interpretation of the available data, the planctomycete Gemmata obscuriglobus contains a nuclear body compartment, and thus possesses a type of cell organization with parallels to the eukaryote nucleus. Here we show that <span class="hlt">pore</span>-like structures occur in internal membranes of G.obscuriglobus and that they have elements structurally similar to eukaryote nuclear <span class="hlt">pores</span>, including a basket, ring-spoke structure, and eight-fold rotational symmetry. Bioinformatic analysis of proteomic data reveals that some of the G. obscuriglobus proteins associated with <span class="hlt">pore</span>-containing membranes possess structural domains found in eukaryote nuclear <span class="hlt">pore</span> complexes. Moreover, immunogold labelling demonstrates localization of one such protein, containing a β-propeller domain, specifically to the G. obscuriglobus <span class="hlt">pore</span>-like structures. Finding bacterial <span class="hlt">pores</span> within internal cell membranes and with structural similarities to eukaryote nuclear <span class="hlt">pore</span> complexes raises the dual possibilities of either hitherto undetected homology or stunning evolutionary convergence. PMID:28146565</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/26553229','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26553229"><span>Repeated Blood <span class="hlt">Pressure</span> Measurements in Childhood in Prediction of Hypertension in Adulthood.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Oikonen, Mervi; Nuotio, Joel; Magnussen, Costan G; Viikari, Jorma S A; Taittonen, Leena; Laitinen, Tomi; Hutri-Kähönen, Nina; Jokinen, Eero; Jula, Antti; Cheung, Michael; Sabin, Matthew A; Daniels, Stephen R; Raitakari, Olli T; Juonala, Markus</p> <p>2016-01-01</p> <p>Hypertension may be predicted from childhood risk factors. Repeated observations of <span class="hlt">abnormal</span> blood <span class="hlt">pressure</span> in childhood may enhance prediction of hypertension and subclinical atherosclerosis in adulthood compared with a single observation. Participants (1927, 54% women) from the Cardiovascular Risk in Young Finns Study had systolic and diastolic blood <span class="hlt">pressure</span> measurements performed when aged 3 to 24 years. Childhood/youth <span class="hlt">abnormal</span> blood <span class="hlt">pressure</span> was defined as above 90th or 95th percentile. After a 21- to 31-year follow-up, at the age of 30 to 45 years, hypertension (>140/90 mm Hg or antihypertensive medication) prevalence was found to be 19%. Carotid intima-media thickness was examined, and high-risk intima-media was defined as intima-media thickness >90th percentile or carotid plaques. Prediction of adulthood hypertension and high-risk intima-media was compared between one observation of <span class="hlt">abnormal</span> blood <span class="hlt">pressure</span> in childhood/youth and multiple observations by improved Pearson correlation coefficients and area under the receiver operating curve. When compared with a single measurement, 2 childhood/youth observations improved the correlation for adult systolic (r=0.44 versus 0.35, P<0.001) and diastolic (r=0.35 versus 0.17, P<0.001) blood <span class="hlt">pressure</span>. In addition, 2 <span class="hlt">abnormal</span> childhood/youth blood <span class="hlt">pressure</span> observations increased the prediction of hypertension in adulthood (0.63 for 2 versus 0.60 for 1 observation, P=0.003). When compared with 2 measurements, third observation did not provide any significant improvement for correlation or prediction (P always >0.05). A higher number of childhood/youth observations of <span class="hlt">abnormal</span> blood <span class="hlt">pressure</span> did not enhance prediction of adult high-risk intima-media thickness. Compared with a single measurement, the prediction of adult hypertension was enhanced by 2 observations of <span class="hlt">abnormal</span> blood <span class="hlt">pressure</span> in childhood/youth. © 2015 American Heart Association, Inc.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/27159417','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/27159417"><span>Hydrochromic Approaches to Mapping Human Sweat <span class="hlt">Pores</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Park, Dong-Hoon; Park, Bum Jun; Kim, Jong-Man</p> <p>2016-06-21</p> <p>Hydrochromic materials, which undergo changes in their light absorption and/or emission properties in response to water, have been extensively investigated as humidity sensors. Recent advances in the design of these materials have led to novel applications, including monitoring the water content of organic solvents, water-jet-based rewritable printing on paper, and hydrochromic mapping of human sweat <span class="hlt">pores</span>. Our interest in this area has focused on the design of hydrochromic materials for human sweat <span class="hlt">pore</span> mapping. We recognized that materials appropriate for this purpose must have balanced sensitivities to water. Specifically, while they should not undergo light absorption and/or emission transitions under ambient moisture conditions, the materials must have sufficiently high hydrochromic sensitivities that they display responses to water secreted from human sweat <span class="hlt">pores</span>. In this Account, we describe investigations that we have carried out to develop hydrochromic substances that are suitable for human sweat <span class="hlt">pore</span> mapping. Polydiacetylenes (PDAs) have been extensively investigated as sensor matrices because of their stimulus-responsive color change property. We found that incorporation of headgroups composed of hygroscopic ions such as cesium or rubidium and carboxylate counterions enables PDAs to undergo a blue-to-red colorimetric transition as well as a fluorescence turn-on response to water. Very intriguingly, the small quantities of water secreted from human sweat <span class="hlt">pores</span> were found to be sufficient to trigger fluorescence turn-on responses of the hydrochromic PDAs, allowing precise mapping of human sweat <span class="hlt">pores</span>. Since the hygroscopic ion-containing PDAs developed in the initial stage display a colorimetric transition under ambient conditions that exist during humid summer periods, a new system was designed. A PDA containing an imidazolium ion was found to be stable under all ambient conditions and showed temperature-dependent hydrochromism corresponding to a</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015MMTB...46.1576Y','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015MMTB...46.1576Y"><span>Characterization of <span class="hlt">Pore</span> Defects and Fatigue Cracks in Die Cast AM60 Using 3D X-ray Computed Tomography</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Yang, Zhuofei; Kang, Jidong; Wilkinson, David S.</p> <p>2015-08-01</p> <p>AM60 high <span class="hlt">pressure</span> die castings have been used in automobile applications to reduce the weight of vehicles. However, the <span class="hlt">pore</span> defects that are inherent in die casting may negatively affect mechanical properties, especially the fatigue properties. Here we have studied damage ( e.g., <span class="hlt">pore</span> defects, fatigue cracks) during strained-controlled fatigue using 3-dimensional X-ray computed tomography (XCT). The fatigue test was interrupted every 2000 cycles and the specimen was removed to be scanned using a desktop micro-CT system. XCT reveals <span class="hlt">pore</span> defects, cracks, and fracture surfaces. The results show that <span class="hlt">pores</span> can be accurately measured and modeled in 3D. Defect bands are found to be made of <span class="hlt">pores</span> under 50 µm (based on volume-equivalent sphere diameter). Larger <span class="hlt">pores</span> are randomly distributed in the region between the defect bands. Observation of fatigue cracks by XCT is performed in three ways such that the 3D model gives the best illustration of crack-porosity interaction while the other two methods, with the cracks being viewed on transverse or longitudinal cross sections, have better detectability on crack initiation and crack tip observation. XCT is also of value in failure analysis on fracture surfaces. By assessing XCT data during fatigue testing and observing fracture surfaces on a 3D model, a better understanding on the crack initiation, crack-porosity interaction, and the morphology of fracture surface is achieved.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013AGUFM.T33F..05O','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013AGUFM.T33F..05O"><span>Time-dependent wellbore breakout growth caused by drilling-induced <span class="hlt">pore</span> <span class="hlt">pressure</span> transients: Implications for estimations of far field stress magnitude</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Olcott, K. A.; Saffer, D. M.; Elsworth, D.</p> <p>2013-12-01</p> <p>One method used to constrain principal stress orientations and magnitudes in the crust combines estimates of rock strength with observations of wellbore failures, including drilling-induced tensile fractures (DITF) and compressional borehole breakouts (BO). This method has been applied at numerous Integrated Ocean Drilling Program (IODP) boreholes drilled into sediments in a wide range of settings, including the Gulf of Mexico, the N. Japan and Costa Rican subduction margins, and the Nankai Trough Accretionary Prism. At Nankai and N. Japan, BO widths defined by logging-while-drilling (LWD) resistivity images have been used to estimate magnitudes of far-field horizontal tectonic stresses. At several drillsites (C0010, C0002, and C0011), sections of the borehole were relogged with LWD after the hole was left open for times ranging from ~30 min to 3 days; times between acquisition were associated with pipe connections (~30 min), cleaning and circulating the hole (up to ~3 hr), and evacuation of the site for weather (~3 days). Relogged portions exhibit widening of BO, hypothesized to reflect time-dependent re-equilibration of instantaneous changes in <span class="hlt">pore</span> fluid <span class="hlt">pressure</span> (Pf) induced by opening the borehole. In this conceptual model, Pf decrease caused by initial excavation of the borehole and resulting changes in the state of stress at the borehole wall lead to an initial strengthening of the sediment. Re-equilibration of Pf results in time-dependent weakening of the sediment and subsequent BO growth. If correct, this hypothesis implies that stress magnitudes estimated by BO widths could be significantly underestimated. We test this idea using a finite-element model in COMSOL multiphysics that couples fluid flow and deformation in a poroelastic medium. We specify far-field horizontal principal stresses (SHmax and Shmin) in the model domain. At the start of simulations/at the time of borehole opening, we impose a decreased stress at the borehole wall. We consider a</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011AGUFM.H31E1217Y','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011AGUFM.H31E1217Y"><span><span class="hlt">Pore</span>-scale simulation of calcium carbonate precipitation and dissolution under highly supersaturated conditions in a microfludic <span class="hlt">pore</span> network</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Yoon, H.; Dewers, T. A.; Valocchi, A. J.; Werth, C. J.</p> <p>2011-12-01</p> <p>Dissolved CO2 during geological CO2 storage may react with minerals in fractured rocks or confined aquifers and cause mineral precipitation. The overall rate of reaction can be affected by coupled processes among hydrodynamics, transport, and reactions at <span class="hlt">pore</span>-scale. <span class="hlt">Pore</span>-scale models of coupled fluid flow, reactive transport, and CaCO3 precipitation and dissolution are applied to account for transient experimental results of CaCO3 precipitation and dissolution under highly supersaturated conditions in a microfluidic <span class="hlt">pore</span> network (i.e., micromodel). <span class="hlt">Pore</span>-scale experiments in the micromodel are used as a basis for understanding coupled physics of systems perturbed by geological CO2 injection. In the micromodel, precipitation is induced by transverse mixing along the centerline in <span class="hlt">pore</span> bodies. Overall, the <span class="hlt">pore</span>-scale model qualitatively captured the governing physics of reactions such as precipitate morphology, precipitation rate, and maximum precipitation area in first few <span class="hlt">pore</span> spaces. In particular, we found that proper estimation of the effective diffusion coefficient and the reactive surface area is necessary to adequately simulate precipitation and dissolution rates. As the model domain increases, the effect of flow patterns affected by precipitation on the overall reaction rate also increases. The model is also applied to account for the effect of different reaction rate laws on mineral precipitation and dissolution at <span class="hlt">pore</span>-scale. Reaction rate laws tested include the linear rate law, nonlinear power law, and newly-developed rate law based on in-situ measurements at nano scale in the literature. Progress on novel methods for upscaling <span class="hlt">pore</span>-scale models for reactive transport are discussed, and are being applied to mineral precipitation patterns observed in natural analogues. H.Y. and T. D. were supported as part of the Center for Frontiers of Subsurface Energy Security, an Energy Frontier Research Center funded by the U.S. Department of Energy, Office of</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ccr.cancer.gov/news/inthejournals/itj_aplan','NCI'); return false;" href="https://ccr.cancer.gov/news/inthejournals/itj_aplan"><span>Small Molecule Disrupts <span class="hlt">Abnormal</span> Gene Fusion Associated with Leukemia | Center for Cancer Research</span></a></p> <p><a target="_blank" href="http://www.cancer.gov">Cancer.gov</a></p> <p></p> <p></p> <p>Rare chromosomal <span class="hlt">abnormalities</span>, called chromosomal translocations, in which part of a chromosome breaks off and becomes attached to another chromosome, can result in the generation of chimeric proteins. These aberrant proteins have unpredictable, and sometimes harmful, functions, including uncontrolled cell growth that can lead to cancer. One type of translocation, in which a portion of the gene encoding nucleoporin 98 (NUP98)—one of about 50 proteins comprising the nuclear <span class="hlt">pore</span> complex through which proteins are shuttled into and out of the nucleus—fuses with another gene, has been shown to result in improper histone modifications. These <span class="hlt">abnormalities</span> alter the gene expression patterns of certain types of hematopoietic, or blood-forming, stem cells, resulting primarily in overexpression of the Hoxa7, Hoxa9,and Hoxa10 genes. NUP98 chromosomal translocations have been associated with many types of leukemia, including acute myeloid leukemia (AML), acute lymphoid leukemia (ALL), chronic myeloid leukemia in blast crisis (CML-bc), and myelodysplastic syndrome (MDS).</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/servlets/purl/1395436','SCIGOV-STC'); return false;" href="https://www.osti.gov/servlets/purl/1395436"><span>Measurements of <span class="hlt">pore</span>-scale flow through apertures</span></a></p> <p><a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a></p> <p>Chojnicki, Kirsten</p> <p></p> <p><span class="hlt">Pore</span>-scale aperture effects on flow in <span class="hlt">pore</span> networks was studied in the laboratory to provide a parameterization for use in transport models. Four cases were considered: regular and irregular pillar/<span class="hlt">pore</span> alignment with and without an aperture. The velocity field of each case was measured and simulated, providing quantitatively comparable results. Two aperture effect parameterizations were considered: permeability and transmission. Permeability values varied by an order of magnitude between the cases with and without apertures. However, transmission did not correlate with permeability. Despite having much greater permeability the regular aperture case permitted less transmission than the regular case. Moreover, both irregularmore » cases had greater transmission than the regular cases, a difference not supported by the permeabilities. Overall, these findings suggest that <span class="hlt">pore</span>-scale aperture effects on flow though a <span class="hlt">pore</span>-network may not be adequately captured by properties such as permeability for applications that are interested in determining particle transport volume and timing.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/28751252','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/28751252"><span><span class="hlt">Pore</span>-forming toxins in Cnidaria.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Podobnik, Marjetka; Anderluh, Gregor</p> <p>2017-12-01</p> <p>The ancient phylum of Cnidaria contains many aquatic species with peculiar lifestyle. In order to survive, these organisms have evolved attack and defense mechanisms that are enabled by specialized cells and highly developed venoms. <span class="hlt">Pore</span>-forming toxins are an important part of their venomous arsenal. Along some other types, the most representative are examples of four protein families that are commonly found in other kingdoms of life: actinoporins, Cry-like proteins, aerolysin-like toxins and MACPF/CDC toxins. Some of the homologues of <span class="hlt">pore</span>-forming toxins may serve other functions, such as in food digestion, development and response against pathogenic organisms. Due to their interesting physico-chemical properties, the cnidarian <span class="hlt">pore</span>-forming toxins may also serve as tools in medical research and nanobiotechnological applications. Copyright © 2017 Elsevier Ltd. All rights reserved.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/pages/biblio/1215609-decreasing-transmembrane-segment-length-greatly-decreases-perfringolysin-pore-size','SCIGOV-DOEP'); return false;" href="https://www.osti.gov/pages/biblio/1215609-decreasing-transmembrane-segment-length-greatly-decreases-perfringolysin-pore-size"><span>Decreasing transmembrane segment length greatly decreases perfringolysin O <span class="hlt">pore</span> size</span></a></p> <p><a target="_blank" href="http://www.osti.gov/pages">DOE PAGES</a></p> <p>Lin, Qingqing; Li, Huilin; Wang, Tong; ...</p> <p>2015-04-08</p> <p>Perfringolysin O (PFO) is a transmembrane (TM) β-barrel protein that inserts into mammalian cell membranes. Once inserted into membranes, PFO assembles into <span class="hlt">pore</span>-forming oligomers containing 30–50 PFO monomers. These form a <span class="hlt">pore</span> of up to 300 Å, far exceeding the size of most other proteinaceous <span class="hlt">pores</span>. In this study, we found that altering PFO TM segment length can alter the size of PFO <span class="hlt">pores</span>. A PFO mutant with lengthened TM segments oligomerized to a similar extent as wild-type PFO, and exhibited <span class="hlt">pore</span>-forming activity and a <span class="hlt">pore</span> size very similar to wild-type PFO as measured by electron microscopy and a leakagemore » assay. In contrast, PFO with shortened TM segments exhibited a large reduction in <span class="hlt">pore</span>-forming activity and <span class="hlt">pore</span> size. This suggests that the interaction between TM segments can greatly affect the size of <span class="hlt">pores</span> formed by TM β-barrel proteins. PFO may be a promising candidate for engineering <span class="hlt">pore</span> size for various applications.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/pages/biblio/1340241-application-pore-scale-reactive-transport-model-natural-analog-reaction-induced-pore-alterations','SCIGOV-DOEP'); return false;" href="https://www.osti.gov/pages/biblio/1340241-application-pore-scale-reactive-transport-model-natural-analog-reaction-induced-pore-alterations"><span>Application of a <span class="hlt">pore</span>-scale reactive transport model to a natural analog for reaction-induced <span class="hlt">pore</span> alterations</span></a></p> <p><a target="_blank" href="http://www.osti.gov/pages">DOE PAGES</a></p> <p>Yoon, Hongkyu; Major, Jonathan; Dewers, Thomas; ...</p> <p>2017-01-05</p> <p>Dissolved CO 2 in the subsurface resulting from geological CO 2 storage may react with minerals in fractured rocks, confined aquifers, or faults, resulting in mineral precipitation and dissolution. The overall rate of reaction can be affected by coupled processes including hydrodynamics, transport, and reactions at the (sub) <span class="hlt">pore</span>-scale. In this work <span class="hlt">pore</span>-scale modeling of coupled fluid flow, reactive transport, and heterogeneous reactions at the mineral surface is applied to account for permeability alterations caused by precipitation-induced <span class="hlt">pore</span>-blocking. This paper is motivated by observations of CO 2 seeps from a natural CO 2 sequestration analog, Crystal Geyser, Utah. Observations alongmore » the surface exposure of the Little Grand Wash fault indicate the lateral migration of CO 2 seep sites (i.e., alteration zones) of 10–50 m width with spacing on the order of ~100 m over time. Sandstone permeability in alteration zones is reduced by 3–4 orders of magnitude by carbonate cementation compared to unaltered zones. One granular porous medium and one fracture network systems are used to conceptually represent permeable porous media and locations of conduits controlled by fault-segment intersections and/or topography, respectively. Simulation cases accounted for a range of reaction regimes characterized by the Damköhler (Da) and Peclet (Pe) numbers. <span class="hlt">Pore</span>-scale simulation results demonstrate that combinations of transport (Pe), geochemical conditions (Da), solution chemistry, and <span class="hlt">pore</span> and fracture configurations contributed to match key patterns observed in the field of how calcite precipitation alters flow paths by <span class="hlt">pore</span> plugging. This comparison of simulation results with field observations reveals mechanistic explanations of the lateral migration and enhances our understanding of subsurface processes associated with the CO 2 injection. In addition, permeability and porosity relations are constructed from <span class="hlt">pore</span>-scale simulations which account for a range of</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3519214','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3519214"><span>Karyotyping, dermatoglyphic, and sweat <span class="hlt">pore</span> analysis of five families affected with ectodermal dysplasia</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Sidhu, Manpreet; Kale, Alka D; Kotrashetti, Vijayalakshmi S</p> <p>2012-01-01</p> <p>Background: Hereditary ectodermal dysplasia is a genetic recessive trait characterized by hypohydrosis, hypotrichosis, and hypodontia. The affected individual show characteristic physiognomy like protruded forehead, depressed nasal bridge, periorbital wrinkling, protruded lips, etc. There is marked decrease in sweat and salivary secretion. Due to skin involvement palm and sole ridge patterns are disrupted. Aim: In this study an attempt has been made to classify the affected members according to the degree of penetrance by pedigree analysis and also study karyotyping for cytogenetics, dermatoglyphic analysis for the various ridge patterns and variations in the number of sweat glands by sweat <span class="hlt">pore</span> analysis in affected individuals. Materials and Methods: A total of five families who were affected with ectodermal dysplasia were considered. Pedigree analysis was drawn up to three generation by obtaining history. Dermatoglyphics and sweat <span class="hlt">pore</span> analysis was done by obtaining palm and finger print impression using stamp pad ink. Karyotyping was done by collecting 3–5 ml peripheral blood. Karyotyping was prepared using lymphocyte culture. Chromosomes were examined at 20 spreads selected randomly under ×100 magnification. Results were analyzed by calculating mean values and percentage was obtained. Results: Karyotyping did not show any <span class="hlt">abnormalities</span>, dermatoglyphic analysis and sweat <span class="hlt">pore</span> counts showed marked variations when compared with normal. Moreover, pedigree analysis confirmed the status of the disease as that of the recessive trait. Conclusion: Large number of affected patients needs to be evaluated for dermatoglypic analysis. Genetic aspect of the disease needs to be looked into the molecular level in an attempt to locate the gene locus responsible for ectodermal dysplasia and its manifestation. PMID:23248471</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/biblio/1438985-importance-filters-microstructure-dynamic-filtration-modeling-gasoline-particulate-filters-gpfs-inhomogeneous-porosity-pore-size-distribution','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/1438985-importance-filters-microstructure-dynamic-filtration-modeling-gasoline-particulate-filters-gpfs-inhomogeneous-porosity-pore-size-distribution"><span>Importance of filter’s microstructure in dynamic filtration modeling of gasoline particulate filters (GPFs): Inhomogeneous porosity and <span class="hlt">pore</span> size distribution</span></a></p> <p><a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a></p> <p>Gong, Jian; Stewart, Mark L.; Zelenyuk, Alla</p> <p></p> <p>The state-of-the-art multiscale modeling of GPFs including channel scale, wall scale, and <span class="hlt">pore</span> scale is described. The microstructures of two GPFs were experimentally characterized. The <span class="hlt">pore</span> size distributions of the GPFs were determined by mercury porosimetry. The porosity was measured by X-ray computed tomography (CT) and found to be inhomogeneous across the substrate wall. The significance of <span class="hlt">pore</span> size distribution with respect to filtration performance was analyzed. The predictions of filtration efficiency were improved by including the <span class="hlt">pore</span> size distribution in the filtration model. A dynamic heterogeneous multiscale filtration (HMF) model was utilized to simulate particulate filtration on a singlemore » channel particulate filter with realistic particulate emissions from a spark-ignition direct-injection (SIDI) gasoline engine. The dynamic evolution of filter’s microstructure and macroscopic filtration characteristics including mass- and number-based filtration efficiencies and <span class="hlt">pressure</span> drop were predicted and discussed. The microstructure of the GPF substrate including inhomogeneous porosity and <span class="hlt">pore</span> size distribution is found to significantly influence local particulate deposition inside the substrate and macroscopic filtration performance and is recommended to be resolved in the filtration model to simulate and evaluate the filtration performance of GPFs.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016Fract..2450053Z','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016Fract..2450053Z"><span>Percolation Laws of a Fractal Fracture-<span class="hlt">Pore</span> Double Medium</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Zhao, Yangsheng; Feng, Zengchao; Lv, Zhaoxing; Zhao, Dong; Liang, Weiguo</p> <p>2016-12-01</p> <p>The fracture-<span class="hlt">pore</span> double porosity medium is one of the most common media in nature, for example, rock mass in strata. Fracture has a more significant effect on fluid flow than a <span class="hlt">pore</span> in a fracture-<span class="hlt">pore</span> double porosity medium. Hence, the fracture effect on percolation should be considered when studying the percolation phenomenon in porous media. In this paper, based on the fractal distribution law, three-dimensional (3D) fracture surfaces, and two-dimensional (2D) fracture traces in rock mass, the locations of fracture surfaces or traces are determined using a random function of uniform distribution. <span class="hlt">Pores</span> are superimposed to build a fractal fracture-<span class="hlt">pore</span> double medium. Numerical experiments were performed to show percolation phenomena in the fracture-<span class="hlt">pore</span> double medium. The percolation threshold can be determined from three independent variables (porosity n, fracture fractal dimension D, and initial value of fracture number N0). Once any two are determined, the percolation probability exists at a critical point with the remaining parameter changing. When the initial value of the fracture number is greater than zero, the percolation threshold in the fracture-<span class="hlt">pore</span> medium is much smaller than that in a <span class="hlt">pore</span> medium. When the fracture number equals zero, the fracture-<span class="hlt">pore</span> medium degenerates to a <span class="hlt">pore</span> medium, and both percolation thresholds are the same.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017JaJAP..56aAF03T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017JaJAP..56aAF03T"><span>Atmospheric-<span class="hlt">pressure</span> plasma activation and surface characterization on polyethylene membrane separator</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Tseng, Yu-Chien; Li, Hsiao-Ling; Huang, Chun</p> <p>2017-01-01</p> <p>The surface hydrophilic activation of a polyethylene membrane separator was achieved using an atmospheric-<span class="hlt">pressure</span> plasma jet. The surface of the atmospheric-<span class="hlt">pressure</span>-plasma-treated membrane separator was found to be highly hydrophilic realized by adjusting the plasma power input. The variations in membrane separator chemical structure were confirmed by Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy. Chemical analysis showed newly formed carbonyl-containing groups and high surface concentrations of oxygen-containing species on the atmospheric-<span class="hlt">pressure</span>-plasma-treated polymeric separator surface. It also showed that surface hydrophilicity primarily increased from the polar component after atmospheric-<span class="hlt">pressure</span> plasma treatment. The surface and <span class="hlt">pore</span> structures of the polyethylene membrane separator were examined by scanning electron microscopy, revealing a slight alteration in the <span class="hlt">pore</span> structure. As a result of the incorporation of polar functionalities by atmospheric-<span class="hlt">pressure</span> plasma activation, the electrolyte uptake and electrochemical impedance of the atmospheric-<span class="hlt">pressure</span>-plasma-treated membrane separator improved. The investigational results show that the separator surface can be controlled by atmospheric-<span class="hlt">pressure</span> plasma surface treatment to tailor the hydrophilicity and enhance the electrochemical performance of lithium ion batteries.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014APS..MARB15009P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014APS..MARB15009P"><span>Transport and Deposition of Nanoparticles in the <span class="hlt">Pore</span> Network of a Reservoir Rock: Effects of <span class="hlt">Pore</span> Surface Heterogeneity and Radial Diffusion</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Pham, Ngoc; Papavassiliou, Dimitrios</p> <p>2014-03-01</p> <p>In this study, transport behavior of nanoparticles under different <span class="hlt">pore</span> surface conditions of consolidated Berea sandstone is numerically investigated. Micro-CT scanning technique is applied to obtain 3D grayscale images of the rock sample geometry. Quantitative characterization, which is based on image analysis is done to obtain physical properties of the <span class="hlt">pore</span> network, such as the <span class="hlt">pore</span> size distribution and the type of each <span class="hlt">pore</span> (dead-end, isolated, and fully connected <span class="hlt">pore</span>). Transport of water through the rock is simulated by employing a 3D lattice Boltzmann method. The trajectories of nanopaticles moving under convection in the simulated flow field and due to molecular diffusion are monitored in the Lagrangian framework. It is assumed in the model that the particle adsorption on the <span class="hlt">pore</span> surface, which is modeled as a pseudo-first order adsorption, is the only factor hindering particle propagation. The effect of <span class="hlt">pore</span> surface heterogeneity to the particle breakthrough is considered, and the role of particle radial diffusion is also addressed in details. The financial support of the Advanced Energy Consortium (AEC BEG08-022) and the computational support of XSEDE (CTS090017) are acknowledged.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li class="active"><span>21</span></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_21 --> <div id="page_22" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li class="active"><span>22</span></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li><a href="#" onclick='return showDiv("page_24");'>24</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="421"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017SPIE10567E..0UW','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017SPIE10567E..0UW"><span>X-ray <span class="hlt">pore</span> optic developments</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Wallace, Kotska; Bavdaz, Marcos; Collon, Maximilien; Beijersbergen, Marco; Kraft, Stefan; Fairbend, Ray; Séguy, Julien; Blanquer, Pascal; Graue, Roland; Kampf, Dirk</p> <p>2017-11-01</p> <p>In support of future x-ray telescopes ESA is developing new optics for the x-ray regime. To date, mass and volume have made x-ray imaging technology prohibitive to planetary remote sensing imaging missions. And although highly successful, the mirror technology used on ESA's XMM-Newton is not sufficient for future, large, x-ray observatories, since physical limits on the mirror packing density mean that aperture size becomes prohibitive. To reduce telescope mass and volume the packing density of mirror shells must be reduced, whilst maintaining alignment and rigidity. Structures can also benefit from a modular optic arrangement. <span class="hlt">Pore</span> optics are shown to meet these requirements. This paper will discuss two <span class="hlt">pore</span> optic technologies under development, with examples of results from measurement campaigns on samples. One activity has centred on the use of coated, silicon wafers, patterned with ribs, that are integrated onto a mandrel whose form has been polished to the required shape. The wafers follow the shape precisely, forming <span class="hlt">pore</span> sizes in the sub-mm region. Individual stacks of mirrors can be manufactured without risk to, or dependency on, each other and aligned in a structure from which they can also be removed without hazard. A breadboard is currently being built to demonstrate this technology. A second activity centres on glass <span class="hlt">pore</span> optics. However an adaptation of micro channel plate technology to form square <span class="hlt">pores</span> has resulted in a monolithic material that can be slumped into an optic form. Alignment and coating of two such plates produces an x-ray focusing optic. A breadboard 20cm aperture optic is currently being built.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4595940','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4595940"><span>Local electrostatic interactions determine the diameter of fusion <span class="hlt">pores</span></span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Guček, Alenka; Jorgačevski, Jernej; Górska, Urszula; Rituper, Boštjan; Kreft, Marko; Zorec, Robert</p> <p>2015-01-01</p> <p>In regulated exocytosis vesicular and plasma membranes merge to form a fusion <span class="hlt">pore</span> in response to stimulation. The nonselective cation HCN channels are involved in the regulation of unitary exocytotic events by at least 2 mechanisms. They can affect SNARE-dependent exocytotic activity indirectly, via the modulation of free intracellular calcium; and/or directly, by altering local cation concentration, which affects fusion <span class="hlt">pore</span> geometry likely via electrostatic interactions. By monitoring membrane capacitance, we investigated how extracellular cation concentration affects fusion <span class="hlt">pore</span> diameter in pituitary cells and astrocytes. At low extracellular divalent cation levels predominantly transient fusion events with widely open fusion <span class="hlt">pores</span> were detected. However, fusion events with predominately narrow fusion <span class="hlt">pores</span> were present at elevated levels of extracellular trivalent cations. These results show that electrostatic interactions likely help determine the stability of discrete fusion <span class="hlt">pore</span> states by affecting fusion <span class="hlt">pore</span> membrane composition. PMID:25835258</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/servlets/purl/1175202','DOE-PATENT-XML'); return false;" href="https://www.osti.gov/servlets/purl/1175202"><span>Conductance valve and <span class="hlt">pressure</span>-to-conductance transducer method and apparatus</span></a></p> <p><a target="_blank" href="http://www.osti.gov/doepatents">DOEpatents</a></p> <p>Schoeniger, Joseph S.; Cummings, Eric B.; Brennan, James S.</p> <p>2005-01-18</p> <p>A device for interrupting or throttling undesired ionic transport through a fluid network is disclosed. The device acts as a fluid valve by reversibly generating a fixed "bubble" in the conducting solvent solution carried by the network. The device comprises a porous hydrophobic structure filling a portion of a connecting channel within the network and optionally incorporates flow restrictor elements at either end of the porous structure that function as <span class="hlt">pressure</span> isolation barriers, and a fluid reservoir connected to the region of the channel containing the porous structure. Also included is a <span class="hlt">pressure</span> pump connected to the fluid reservoir. The device operates by causing the pump to vary the hydraulic <span class="hlt">pressure</span> to a quantity of solvent solution held within the reservoir and porous structure. At high <span class="hlt">pressures</span>, most or all of the <span class="hlt">pores</span> of the structure are filled with conducting liquid so the ionic conductance is high. At lower <span class="hlt">pressures</span>, only a fraction of the <span class="hlt">pores</span> are filled with liquid, so ionic conductivity is lower. Below a threshold <span class="hlt">pressure</span>, the porous structure contains only vapor, so there is no liquid conduction path. The device therefore effectively throttles ionic transport through the porous structure and acts as a "conductance valve" or "<span class="hlt">pressure</span>-to-conductance" transducer within the network.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3077598','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3077598"><span>A Specific Two-<span class="hlt">pore</span> Domain Potassium Channel Blocker Defines the Structure of the TASK-1 Open <span class="hlt">Pore</span>*</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Streit, Anne K.; Netter, Michael F.; Kempf, Franca; Walecki, Magdalena; Rinné, Susanne; Bollepalli, Murali K.; Preisig-Müller, Regina; Renigunta, Vijay; Daut, Jürgen; Baukrowitz, Thomas; Sansom, Mark S. P.; Stansfeld, Phillip J.; Decher, Niels</p> <p>2011-01-01</p> <p>Two-<span class="hlt">pore</span> domain potassium (K2P) channels play a key role in setting the membrane potential of excitable cells. Despite their role as putative targets for drugs and general anesthetics, little is known about the structure and the drug binding site of K2P channels. We describe A1899 as a potent and highly selective blocker of the K2P channel TASK-1. As A1899 acts as an open-channel blocker and binds to residues forming the wall of the central cavity, the drug was used to further our understanding of the channel <span class="hlt">pore</span>. Using alanine mutagenesis screens, we have identified residues in both <span class="hlt">pore</span> loops, the M2 and M4 segments, and the halothane response element to form the drug binding site of TASK-1. Our experimental data were used to validate a K2P open-<span class="hlt">pore</span> homology model of TASK-1, providing structural insights for future rational design of drugs targeting K2P channels. PMID:21362619</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016SPIE.9706E..0VR','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016SPIE.9706E..0VR"><span>Conductivity affects nanosecond electrical pulse induced <span class="hlt">pressure</span> transient formation</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Roth, Caleb C.; Barnes, Ronald A.; Ibey, Bennett L.; Beier, Hope T.; Glickman, Randolph D.</p> <p>2016-03-01</p> <p>Nanoporation occurs in cells exposed to high amplitude short duration (< 1μs) electrical pulses. The biophysical mechanism(s) responsible for nanoporation is unknown although several theories exist. Current theories focus exclusively on the electrical field, citing electrostriction, water dipole alignment and/or electrodeformation as the primary mechanisms for <span class="hlt">pore</span> formation. Our group has shown that mechanical forces of substantial magnitude are also generated during nsEP exposures. We hypothesize that these mechanical forces may contribute to <span class="hlt">pore</span> formation. In this paper, we report that alteration of the conductivity of the exposure solution also altered the level of mechanical forces generated during a nsEP exposure. By reducing the conductivity of the exposure solutions, we found that we could completely eliminate any <span class="hlt">pressure</span> transients normally created by nsEP exposure. The data collected for this proceeding does not definitively show that the <span class="hlt">pressure</span> transients previously identified contribute to nanoporation; however; it indicates that conductivity influences both survival and <span class="hlt">pressure</span> transient formation.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018GeoJI.212.2226L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018GeoJI.212.2226L"><span>Experimental study and theoretical interpretation of saturation effect on ultrasonic velocity in tight sandstones under different <span class="hlt">pressure</span> conditions</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Li, Dongqing; Wei, Jianxin; Di, Bangrang; Ding, Pinbo; Huang, Shiqi; Shuai, Da</p> <p>2018-03-01</p> <p>Understanding the influence of lithology, porosity, permeability, <span class="hlt">pore</span> structure, fluid content and fluid distribution on the elastic wave properties of porous rocks is of great significance for seismic exploration. However, unlike conventional sandstones, the petrophysical characteristics of tight sandstones are more complex and less understood. To address this problem, we measured ultrasonic velocity in partially saturated tight sandstones under different effective <span class="hlt">pressures</span>. A new model is proposed, combining the Mavko-Jizba-Gurevich relations and the White model. The proposed model can satisfactorily simulate and explain the saturation dependence and <span class="hlt">pressure</span> dependence of velocity in tight sandstones. Under low effective <span class="hlt">pressure</span>, the relationship of P-wave velocity to saturation is pre-dominantly attributed to local (<span class="hlt">pore</span> scale) fluid flow and inhomogeneous <span class="hlt">pore</span>-fluid distribution (large scale). At higher effective <span class="hlt">pressure</span>, local fluid flow gradually decreases, and P-wave velocity gradually shifts from uniform saturation towards patchy saturation. We also find that shear modulus is more sensitive to saturation at low effective <span class="hlt">pressures</span>. The new model includes wetting ratio, an adjustable parameter that is closely related to the relationship between shear modulus and saturation.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017E%26PSL.457...38B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017E%26PSL.457...38B"><span><span class="hlt">Pore</span> geometry as a control on rock strength</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Bubeck, A.; Walker, R. J.; Healy, D.; Dobbs, M.; Holwell, D. A.</p> <p>2017-01-01</p> <p>The strength of rocks in the subsurface is critically important across the geosciences, with implications for fluid flow, mineralisation, seismicity, and the deep biosphere. Most studies of porous rock strength consider the scalar quantity of porosity, in which strength shows a broadly inverse relationship with total porosity, but <span class="hlt">pore</span> shape is not explicitly defined. Here we use a combination of uniaxial compressive strength measurements of isotropic and anisotropic porous lava samples, and numerical modelling to consider the influence of <span class="hlt">pore</span> shape on rock strength. Micro computed tomography (CT) shows that <span class="hlt">pores</span> range from sub-spherical to elongate and flat ellipsoids. Samples that contain flat <span class="hlt">pores</span> are weaker if compression is applied parallel to the short axis (i.e. across the minimum curvature), compared to compression applied parallel to the long axis (i.e. across the maximum curvature). Numerical models for elliptical <span class="hlt">pores</span> show that compression applied across the minimum curvature results in relatively broad amplification of stress, compared to compression applied across the maximum curvature. Certain <span class="hlt">pore</span> shapes may be relatively stable and remain open in the upper crust under a given remote stress field, while others are inherently weak. Quantifying the shape, orientations, and statistical distributions of <span class="hlt">pores</span> is therefore a critical step in strength testing of rocks.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/28950572','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/28950572"><span>Edge contact angle and modified Kelvin equation for condensation in open <span class="hlt">pores</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Malijevský, Alexandr; Parry, Andrew O; Pospíšil, Martin</p> <p>2017-08-01</p> <p>We consider capillary condensation transitions occurring in open slits of width L and finite height H immersed in a reservoir of vapor. In this case the <span class="hlt">pressure</span> at which condensation occurs is closer to saturation compared to that occurring in an infinite slit (H=∞) due to the presence of two menisci that are pinned near the open ends. Using macroscopic arguments, we derive a modified Kelvin equation for the <span class="hlt">pressure</span> p_{cc}(L;H) at which condensation occurs and show that the two menisci are characterized by an edge contact angle θ_{e} that is always larger than the equilibrium contact angle θ, only equal to it in the limit of macroscopic H. For walls that are completely wet (θ=0) the edge contact angle depends only on the aspect ratio of the capillary and is well described by θ_{e}≈sqrt[πL/2H] for large H. Similar results apply for condensation in cylindrical <span class="hlt">pores</span> of finite length. We test these predictions against numerical results obtained using a microscopic density-functional model where the presence of an edge contact angle characterizing the shape of the menisci is clearly visible from the density profiles. Below the wetting temperature T_{w} we find very good agreement for slit <span class="hlt">pores</span> of widths of just a few tens of molecular diameters, while above T_{w} the modified Kelvin equation only becomes accurate for much larger systems.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017AdWR..109..158A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017AdWR..109..158A"><span>Automatic measurement of contact angle in <span class="hlt">pore</span>-space images</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>AlRatrout, Ahmed; Raeini, Ali Q.; Bijeljic, Branko; Blunt, Martin J.</p> <p>2017-11-01</p> <p>A new approach is presented to measure the in-situ contact angle (θ) between immiscible fluids, applied to segmented <span class="hlt">pore</span>-scale X-ray images. We first identify and mesh the fluid/fluid and fluid/solid interfaces. A Gaussian smoothing is applied to this mesh to eliminate artifacts associated with the voxelized nature of the image, while preserving large-scale features of the rock surface. Then, for the fluid/fluid interface we apply an additional smoothing and adjustment of the mesh to impose a constant curvature. We then track the three-phase contact line, and the two vectors that have a direction perpendicular to both surfaces: the contact angle is found from the dot product of these vectors where they meet at the contact line. This calculation can be applied at every point on the mesh at the contact line. We automatically generate contact angle values representing each invaded <span class="hlt">pore</span>-element in the image with high accuracy. To validate the approach, we first study synthetic three-dimensional images of a spherical droplet of oil residing on a tilted flat solid surface surrounded by brine and show that our results are accurate to within 3° if the sphere diameter is 2 or more voxels. We then apply this method to oil/brine systems imaged at ambient temperature and reservoir <span class="hlt">pressure</span> (10MPa) using X-ray microtomography (Singh et al., 2016). We analyse an image volume of diameter approximately 4.6 mm and 10.7 mm long, obtaining hundreds of thousands of values from a dataset with around 700 million voxels. We show that in a system of altered wettability, contact angles both less than and greater than 90° can be observed. This work provides a rapid method to provide an accurate characterization of <span class="hlt">pore</span>-scale wettability, which is important for the design and assessment of hydrocarbon recovery and carbon dioxide storage.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/biblio/1385988-electroosmotic-flow-rectification-membranes-asymmetrically-shaped-pores-effects-current-pore-density','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/1385988-electroosmotic-flow-rectification-membranes-asymmetrically-shaped-pores-effects-current-pore-density"><span>Electroosmotic Flow Rectification in Membranes with Asymmetrically Shaped <span class="hlt">Pores</span>: Effects of Current and <span class="hlt">Pore</span> Density</span></a></p> <p><a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a></p> <p>Bishop, Gregory W.; Lopez, Marcos M.; Ramiah Rajasekaran, Pradeep</p> <p>2015-07-09</p> <p>We have recently demonstrated a new electrokinetic phenomenon—electroosmotic flow rectification in membranes with asymmetrically shaped <span class="hlt">pores</span>. Flow rectification means that at constant driving force the flow rate in one direction through the membrane is faster than the flow rate in the opposite direction. EOF rectification could be of practical use in microfluidic devices incorporating porous membranes, but additional research is required. We explore here the effects of two key experimental variables—current density used to drive flow through the membrane and membrane <span class="hlt">pore</span> density—on EOF rectification. We have found that the extent of EOF rectification, as quantified by the rectification ratio,more » increases with increasing current density. In contrast, the rectification ratio decreases with increasing membrane <span class="hlt">pore</span> density. We propose explanations for these results based on simple EOF and membrane-transport theories.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5404929','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5404929"><span>Dilation of fusion <span class="hlt">pores</span> by crowding of SNARE proteins</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Wu, Zhenyong; Bello, Oscar D; Thiyagarajan, Sathish; Auclair, Sarah Marie; Vennekate, Wensi; Krishnakumar, Shyam S; O'Shaughnessy, Ben; Karatekin, Erdem</p> <p>2017-01-01</p> <p>Hormones and neurotransmitters are released through fluctuating exocytotic fusion <span class="hlt">pores</span> that can flicker open and shut multiple times. Cargo release and vesicle recycling depend on the fate of the <span class="hlt">pore</span>, which may reseal or dilate irreversibly. <span class="hlt">Pore</span> nucleation requires zippering between vesicle-associated v-SNAREs and target membrane t-SNAREs, but the mechanisms governing the subsequent <span class="hlt">pore</span> dilation are not understood. Here, we probed the dilation of single fusion <span class="hlt">pores</span> using v-SNARE-reconstituted ~23-nm-diameter discoidal nanolipoprotein particles (vNLPs) as fusion partners with cells ectopically expressing cognate, 'flipped' t-SNAREs. <span class="hlt">Pore</span> nucleation required a minimum of two v-SNAREs per NLP face, and further increases in v-SNARE copy numbers did not affect nucleation rate. By contrast, the probability of <span class="hlt">pore</span> dilation increased with increasing v-SNARE copies and was far from saturating at 15 v-SNARE copies per face, the NLP capacity. Our experimental and computational results suggest that SNARE availability may be pivotal in determining whether neurotransmitters or hormones are released through a transient ('kiss and run') or an irreversibly dilating <span class="hlt">pore</span> (full fusion). DOI: http://dx.doi.org/10.7554/eLife.22964.001 PMID:28346138</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4704107','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4704107"><span><span class="hlt">Pore</span> dilation reconsidered</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Bean, Bruce P</p> <p>2015-01-01</p> <p>Previous experiments have suggested that many P2X family channels undergo a time-dependent process of <span class="hlt">pore</span> dilation when activated by ATP. Li et al. now propose a different interpretation of the key experiments. PMID:26505561</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013AGUFM.H33L..02H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013AGUFM.H33L..02H"><span>Multiple Approaches to Characterizing Nano-<span class="hlt">Pore</span> Structure of Barnett Shale</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Hu, Q.; Gao, Z.; Ewing, R. P.; Dultz, S.; Kaufmann, J.; Hamamoto, S.; Webber, B.; Ding, M.</p> <p>2013-12-01</p> <p>Microscopic characteristics of porous media - <span class="hlt">pore</span> shape, <span class="hlt">pore</span>-size distribution, and <span class="hlt">pore</span> connectivity - control fluid flow and mass transport. This presentation discusses various approaches to investigating nano-<span class="hlt">pore</span> structure of Barnett shale, with its implications in gas production behavior. The innovative approaches include imbibition, tracer diffusion, edge-accessible porosity, porosimetry (mercury intrusion porosimetry, nitrogen and water vapor sorption isotherms, and nuclear magnetic resonance cyroporometry), and imaging (Wood's metal impregnation followed with laser ablation-inductively coupled plasma-mass spectrometry, focused ion beam/scanning electron microscopy, and small angle neutron scattering). Results show that the shale <span class="hlt">pores</span> are predominantly in the nm size range, with measured median <span class="hlt">pore</span>-throat diameters about 5 nm. But small <span class="hlt">pore</span> size is not the major contributor to low gas recovery; rather, the low mass diffusivity appears to be caused by low <span class="hlt">pore</span> connectivity of Barnett shale. Chemical diffusion in sparsely-connected <span class="hlt">pore</span> spaces is not well described by classical Fickian behavior; anomalous behavior is suggested by percolation theory, and confirmed by results of imbibition and diffusion tests. Our evolving complementary approaches, with their several advantages and disadvantages, provide a rich toolbox for tackling the nano-<span class="hlt">pore</span> structure characteristics of shales and other natural rocks.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016SolE....7..929M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016SolE....7..929M"><span>X-ray CT analysis of <span class="hlt">pore</span> structure in sand</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Mukunoki, Toshifumi; Miyata, Yoshihisa; Mikami, Kazuaki; Shiota, Erika</p> <p>2016-06-01</p> <p>The development of microfocused X-ray computed tomography (CT) devices enables digital imaging analysis at the <span class="hlt">pore</span> scale. The applications of these devices are diverse in soil mechanics, geotechnical and geoenvironmental engineering, petroleum engineering, and agricultural engineering. In particular, the imaging of the <span class="hlt">pore</span> space in porous media has contributed to numerical simulations for single-phase and multiphase flows or contaminant transport through the <span class="hlt">pore</span> structure as three-dimensional image data. These obtained results are affected by the <span class="hlt">pore</span> diameter; therefore, it is necessary to verify the image preprocessing for the image analysis and to validate the <span class="hlt">pore</span> diameters obtained from the CT image data. Moreover, it is meaningful to produce the physical parameters in a representative element volume (REV) and significant to define the dimension of the REV. This paper describes the underlying method of image processing and analysis and discusses the physical properties of Toyoura sand for the verification of the image analysis based on the definition of the REV. On the basis of the obtained verification results, a <span class="hlt">pore</span>-diameter analysis can be conducted and validated by a comparison with the experimental work and image analysis. The <span class="hlt">pore</span> diameter is deduced from Young-Laplace's law and a water retention test for the drainage process. The results from previous study and perforated-<span class="hlt">pore</span> diameter originally proposed in this study, called the voxel-percolation method (VPM), are compared in this paper. In addition, the limitations of the REV, the definition of the <span class="hlt">pore</span> diameter, and the effectiveness of the VPM for an assessment of the <span class="hlt">pore</span> diameter are discussed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015AGUFM.H41C1310H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AGUFM.H41C1310H"><span>Wettability effect on capillary trapping of supercritical CO2 at <span class="hlt">pore</span>-scale: micromodel experiment and numerical modeling</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Hu, R.; Wan, J.</p> <p>2015-12-01</p> <p>Wettability of reservoir minerals along <span class="hlt">pore</span> surfaces plays a controlling role in capillary trapping of supercritical (sc) CO2 in geologic carbon sequestration. The mechanisms controlling scCO2 residual trapping are still not fully understood. We studied the effect of <span class="hlt">pore</span> surface wettability on CO2 residual saturation at the <span class="hlt">pore</span>-scale using engineered high <span class="hlt">pressure</span> and high temperature micromodel (transparent <span class="hlt">pore</span> networks) experiments and numerical modeling. Through chemical treatment of the micromodel <span class="hlt">pore</span> surfaces, water-wet, intermediate-wet, and CO2-wet micromodels can be obtained. Both drainage and imbibition experiments were conducted at 8.5 MPa and 45 °C with controlled flow rate. Dynamic images of fluid-fluid displacement processes were recorded using a microscope with a CCD camera. Residual saturations were determined by analysis of late stage imbibition images of flow path structures. We performed direct numerical simulations of the full Navier-Stokes equations using a volume-of-fluid based finite-volume framework for the primary drainage and the followed imbibition for the micromodel experiments with different contact angles. The numerical simulations agreed well with our experimental observations. We found that more scCO2 can be trapped within the CO2-wet micromodel whereas lower residual scCO2 saturation occurred within the water-wet micromodels in both our experiments and the numerical simulations. These results provide direct and consistent evidence of the effect of wettability, and have important implications for scCO2 trapping in geologic carbon sequestration.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017APS..DFDG35003J','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017APS..DFDG35003J"><span><span class="hlt">Pore</span>-scale modeling of phase change in porous media</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Juanes, Ruben; Cueto-Felgueroso, Luis; Fu, Xiaojing</p> <p>2017-11-01</p> <p>One of the main open challenges in <span class="hlt">pore</span>-scale modeling is the direct simulation of flows involving multicomponent mixtures with complex phase behavior. Reservoir fluid mixtures are often described through cubic equations of state, which makes diffuse interface, or phase field theories, particularly appealing as a modeling framework. What is still unclear is whether equation-of-state-driven diffuse-interface models can adequately describe processes where surface tension and wetting phenomena play an important role. Here we present a diffuse interface model of single-component, two-phase flow (a van der Waals fluid) in a porous medium under different wetting conditions. We propose a simplified Darcy-Korteweg model that is appropriate to describe flow in a Hele-Shaw cell or a micromodel, with a gap-averaged velocity. We study the ability of the diffuse-interface model to capture capillary <span class="hlt">pressure</span> and the dynamics of vaporization/condensation fronts, and show that the model reproduces <span class="hlt">pressure</span> fluctuations that emerge from abrupt interface displacements (Haines jumps) and from the break-up of wetting films.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/servlets/purl/1262168','SCIGOV-STC'); return false;" href="https://www.osti.gov/servlets/purl/1262168"><span>Laser powder-bed fusion additive manufacturing: Physics of complex melt flow and formation mechanisms of <span class="hlt">pores</span>, spatter, and denudation zones</span></a></p> <p><a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a></p> <p>Khairallah, Saad A.; Anderson, Andrew T.; Rubenchik, Alexander</p> <p></p> <p>Our study demonstrates the significant effect of the recoil <span class="hlt">pressure</span> and Marangoni convection in laser powder bed fusion (L-PBF) of 316L stainless steel. A three-dimensional high fidelity powder-scale model reveals how the strong dynamical melt flow generates <span class="hlt">pore</span> defects, material spattering (sparking), and denudation zones. The melt track is divided into three sections: a topological depression, a transition and a tail region, each being the location of specific physical effects. The inclusion of laser ray-tracing energy deposition in the powder-scale model improves over traditional volumetric energy deposition. It enables partial particle melting, which impacts <span class="hlt">pore</span> defects in the denudation zone.more » Different <span class="hlt">pore</span> formation mechanisms are observed at the edge of a scan track, at the melt pool bottom (during collapse of the pool depression), and at the end of the melt track (during laser power ramp down). Finally, we discuss remedies to these undesirable <span class="hlt">pores</span> are discussed. The results are validated against the experiments and the sensitivity to laser absorptivity.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/pages/biblio/1262168-laser-powder-bed-fusion-additive-manufacturing-physics-complex-melt-flow-formation-mechanisms-pores-spatter-denudation-zones','SCIGOV-DOEP'); return false;" href="https://www.osti.gov/pages/biblio/1262168-laser-powder-bed-fusion-additive-manufacturing-physics-complex-melt-flow-formation-mechanisms-pores-spatter-denudation-zones"><span>Laser powder-bed fusion additive manufacturing: Physics of complex melt flow and formation mechanisms of <span class="hlt">pores</span>, spatter, and denudation zones</span></a></p> <p><a target="_blank" href="http://www.osti.gov/pages">DOE PAGES</a></p> <p>Khairallah, Saad A.; Anderson, Andrew T.; Rubenchik, Alexander; ...</p> <p>2016-02-23</p> <p>Our study demonstrates the significant effect of the recoil <span class="hlt">pressure</span> and Marangoni convection in laser powder bed fusion (L-PBF) of 316L stainless steel. A three-dimensional high fidelity powder-scale model reveals how the strong dynamical melt flow generates <span class="hlt">pore</span> defects, material spattering (sparking), and denudation zones. The melt track is divided into three sections: a topological depression, a transition and a tail region, each being the location of specific physical effects. The inclusion of laser ray-tracing energy deposition in the powder-scale model improves over traditional volumetric energy deposition. It enables partial particle melting, which impacts <span class="hlt">pore</span> defects in the denudation zone.more » Different <span class="hlt">pore</span> formation mechanisms are observed at the edge of a scan track, at the melt pool bottom (during collapse of the pool depression), and at the end of the melt track (during laser power ramp down). Finally, we discuss remedies to these undesirable <span class="hlt">pores</span> are discussed. The results are validated against the experiments and the sensitivity to laser absorptivity.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20110004218','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20110004218"><span>High temperature ion channels and <span class="hlt">pores</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Cheley, Stephen (Inventor); Gu, Li Qun (Inventor); Bayley, Hagan (Inventor); Kang, Xiaofeng (Inventor)</p> <p>2011-01-01</p> <p>The present invention includes an apparatus, system and method for stochastic sensing of an analyte to a protein <span class="hlt">pore</span>. The protein <span class="hlt">pore</span> may be an engineer protein <span class="hlt">pore</span>, such as an ion channel at temperatures above 55.degree. C. and even as high as near 100.degree. C. The analyte may be any reactive analyte, including chemical weapons, environmental toxins and pharmaceuticals. The analyte covalently bonds to the sensor element to produce a detectable electrical current signal. Possible signals include change in electrical current. Detection of the signal allows identification of the analyte and determination of its concentration in a sample solution. Multiple analytes present in the same solution may also be detected.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://pubs.er.usgs.gov/publication/70028566','USGSPUBS'); return false;" href="https://pubs.er.usgs.gov/publication/70028566"><span>Continuous borehole strain and <span class="hlt">pore</span> <span class="hlt">pressure</span> in the near field of the 28 September 2004 M 6.0 parkfield, California, earthquake: Implications for nucleation, fault response, earthquake prediction and tremor</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Johnston, M.J.S.; Borcherdt, R.D.; Linde, A.T.; Gladwin, M.T.</p> <p>2006-01-01</p> <p>Near-field observations of high-precision borehole strain and <span class="hlt">pore</span> <span class="hlt">pressure</span>, show no indication of coherent accelerating strain or <span class="hlt">pore</span> <span class="hlt">pressure</span> during the weeks to seconds before the 28 September 2004 M 6.0 Parkfield earthquake. Minor changes in strain rate did occur at a few sites during the last 24 hr before the earthquake but these changes are neither significant nor have the form expected for strain during slip coalescence initiating fault failure. Seconds before the event, strain is stable at the 10-11 level. Final prerupture nucleation slip in the hypocentral region is constrained to have a moment less than 2 ?? 1012 N m (M 2.2) and a source size less than 30 m. Ground displacement data indicate similar constraints. Localized rupture nucleation and runaway precludes useful prediction of damaging earthquakes. Coseismic dynamic strains of about 10 microstrain peak-to-peak were superimposed on volumetric strain offsets of about 0.5 microstrain to the northwest of the epicenter and about 0.2 microstrain to the southeast of the epicenter, consistent with right lateral slip. Observed strain and Global Positioning System (GPS) offsets can be simply fit with 20 cm of slip between 4 and 10 km on a 20-km segment of the fault north of Gold Hill (M0 = 7 ?? 1017 N m). Variable slip inversion models using GPS data and seismic data indicate similar moments. Observed postseismic strain is 60% to 300% of the coseismic strain, indicating incomplete release of accumulated strain. No measurable change in fault zone compliance preceding or following the earthquake is indicated by stable earth tidal response. No indications of strain change accompany nonvolcanic tremor events reported prior to and following the earthquake.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li class="active"><span>22</span></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li><a href="#" onclick='return showDiv("page_24");'>24</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_22 --> <div id="page_23" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li class="active"><span>23</span></li> <li><a href="#" onclick='return showDiv("page_24");'>24</a></li> <li><a href="#" onclick='return showDiv("page_25");'>25</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="441"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013EGUGA..1514106H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013EGUGA..1514106H"><span>Unfitted Two-Phase Flow Simulations in <span class="hlt">Pore</span>-Geometries with Accurate</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Heimann, Felix; Engwer, Christian; Ippisch, Olaf; Bastian, Peter</p> <p>2013-04-01</p> <p>The development of better macro scale models for multi-phase flow in porous media is still impeded by the lack of suitable methods for the simulation of such flow regimes on the <span class="hlt">pore</span> scale. The highly complicated geometry of natural porous media imposes requirements with regard to stability and computational efficiency which current numerical methods fail to meet. Therefore, current simulation environments are still unable to provide a thorough understanding of porous media in multi-phase regimes and still fail to reproduce well known effects like hysteresis or the more peculiar dynamics of the capillary fringe with satisfying accuracy. Although flow simulations in <span class="hlt">pore</span> geometries were initially the domain of Lattice-Boltzmann and other particle methods, the development of Galerkin methods for such applications is important as they complement the range of feasible flow and parameter regimes. In the recent past, it has been shown that unfitted Galerkin methods can be applied efficiently to topologically demanding geometries. However, in the context of two-phase flows, the interface of the two immiscible fluids effectively separates the domain in two sub-domains. The exact representation of such setups with multiple independent and time depending geometries exceeds the functionality of common unfitted methods. We present a new approach to <span class="hlt">pore</span> scale simulations with an unfitted discontinuous Galerkin (UDG) method. Utilizing a recursive sub-triangulation algorithm, we extent the UDG method to setups with multiple independent geometries. This approach allows an accurate representation of the moving contact line and the interface conditions, i.e. the <span class="hlt">pressure</span> jump across the interface. Example simulations in two and three dimensions illustrate and verify the stability and accuracy of this approach.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4021889','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4021889"><span>Comparison of Polytetrafluoroethylene Flat-Sheet Membranes with Different <span class="hlt">Pore</span> Sizes in Application to Submerged Membrane Bioreactor</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Nittami, Tadashi; Hitomi, Tetsuo; Matsumoto, Kanji; Nakamura, Kazuho; Ikeda, Takaharu; Setoguchi, Yoshihiro; Motoori, Manabu</p> <p>2012-01-01</p> <p>This study focused on phase separation of activated sludge mixed liquor by flat-sheet membranes of polytetrafluoroethylene (PTFE). A 20 liter working volume lab-scale MBR incorporating immersed PTFE flat-sheet membrane modules with different <span class="hlt">pore</span> sizes (0.3, 0.5 and 1.0 μm) was operated for 19 days treating a synthetic wastewater. The experiment was interrupted twice at days 5 and 13 when the modules were removed and cleaned physically and chemically in sequence. The pure water permeate flux of each membrane module was measured before and after each cleaning step to calculate membrane resistances. Results showed that fouling of membrane modules with 0.3 μm <span class="hlt">pore</span> size was more rapid than other membrane modules with different <span class="hlt">pore</span> sizes (0.5 and 1.0 μm). On the other hand, it was not clear whether fouling of the 0.5 μm membrane module was more severe than that of the 1.0 μm membrane module. This was partly because of the membrane condition after chemical cleaning, which seemed to determine the fouling of those modules over the next period. When irreversible resistance (Ri) i.e., differences in membrane resistance before use and after chemical cleaning was high, the transmembrane <span class="hlt">pressure</span> increased quickly during the next period irrespective of membrane <span class="hlt">pore</span> size. PMID:24958174</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/servlets/purl/1113799','DOE-PATENT-XML'); return false;" href="https://www.osti.gov/servlets/purl/1113799"><span>Energy conversion device with support member having <span class="hlt">pore</span> channels</span></a></p> <p><a target="_blank" href="http://www.osti.gov/doepatents">DOEpatents</a></p> <p>Routkevitch, Dmitri [Longmont, CO; Wind, Rikard A [Johnstown, CO</p> <p>2014-01-07</p> <p>Energy devices such as energy conversion devices and energy storage devices and methods for the manufacture of such devices. The devices include a support member having an array of <span class="hlt">pore</span> channels having a small average <span class="hlt">pore</span> channel diameter and having a <span class="hlt">pore</span> channel length. Material layers that may include energy conversion materials and conductive materials are coaxially disposed within the <span class="hlt">pore</span> channels to form material rods having a relatively small cross-section and a relatively long length. By varying the structure of the materials in the <span class="hlt">pore</span> channels, various energy devices can be fabricated, such as photovoltaic (PV) devices, radiation detectors, capacitors, batteries and the like.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://cfpub.epa.gov/si/si_public_record_report.cfm?dirEntryId=126482&Lab=NRMRL&keyword=contractor&actType=&TIMSType=+&TIMSSubTypeID=&DEID=&epaNumber=&ntisID=&archiveStatus=Both&ombCat=Any&dateBeginCreated=&dateEndCreated=&dateBeginPublishedPresented=&dateEndPublishedPresented=&dateBeginUpdated=&dateEndUpdated=&dateBeginCompleted=&dateEndCompleted=&personID=&role=Any&journalID=&publisherID=&sortBy=revisionDate&count=50','EPA-EIMS'); return false;" href="https://cfpub.epa.gov/si/si_public_record_report.cfm?dirEntryId=126482&Lab=NRMRL&keyword=contractor&actType=&TIMSType=+&TIMSSubTypeID=&DEID=&epaNumber=&ntisID=&archiveStatus=Both&ombCat=Any&dateBeginCreated=&dateEndCreated=&dateBeginPublishedPresented=&dateEndPublishedPresented=&dateBeginUpdated=&dateEndUpdated=&dateBeginCompleted=&dateEndCompleted=&personID=&role=Any&journalID=&publisherID=&sortBy=revisionDate&count=50"><span>DESIGN INFORMATION ON FINE <span class="hlt">PORE</span> AERATION SYSTEMS</span></a></p> <p><a target="_blank" href="http://oaspub.epa.gov/eims/query.page">EPA Science Inventory</a></p> <p></p> <p></p> <p>Field studies were conducted over several years at municipal wastewater treatment plants employing line <span class="hlt">pore</span> diffused aeration systems. These studies were designed to produce reliable information on the performance and operational requirements of fine <span class="hlt">pore</span> devices under process ...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/biblio/22587074-distribution-mechanism-pore-formation-copper-foams-fabricated-lost-carbonate-sintering-method','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/22587074-distribution-mechanism-pore-formation-copper-foams-fabricated-lost-carbonate-sintering-method"><span>The distribution and mechanism of <span class="hlt">pore</span> formation in copper foams fabricated by Lost Carbonate Sintering method</span></a></p> <p><a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a></p> <p>Shahzeydi, Mohammad Hosein; Parvanian, Amir Masoud; Panjepour, Masoud, E-mail: panjepour@cc.iut.ac.ir</p> <p>2016-01-15</p> <p>In this research, utilizing X-ray computed tomography (XCT), geometrical characterization, and <span class="hlt">pore</span> formation mechanisms of highly porous copper foams manufactured by powder metallurgical (PM) process are investigated. Open-cell copper foams with porosity percentages of 60% and 80% and with a <span class="hlt">pore</span> size within the range of 300–600 μm were manufactured by using potassium carbonate as a space holder agent via the Lost Carbonate Sintering (LCS) technique. XCT and SEM were also employed to investigate the three-dimensional structure of foams and to find the effect of the parameters of the space holders on the structural properties of copper foams. The resultmore » showed an excellent correlation between the structural properties of the foams including the size and shape of the <span class="hlt">pores</span>, porosity percentage, volume percentage, particle size, and the shape of the sacrificial agent used. Also, the advanced image analysis of XCT images indicated fluctuations up to ± 10% in porosity distribution across different cross-sections of the foams. Simultaneous thermal analysis (STA: DTA–TG) was also used to study the thermal history of the powders used during the manufacturing process of the foams. The results indicated that the melting and thermal decomposition of the potassium carbonate occurred simultaneously at 920 °C and created the porous structure of the foams. By combining the STA result with the result of the tension analysis of cell walls, the mechanisms of open-<span class="hlt">pore</span> formation were suggested. In fact, most open <span class="hlt">pores</span> in the samples were formed due to the direct contact of potassium carbonate particles with each other in green compact. Also, it was found that the thermal decomposition of potassium carbonate particles into gaseous CO{sub 2} led to the production of gas <span class="hlt">pressure</span> inside the closed <span class="hlt">pores</span>, which eventually caused the creation of cracks on the cell walls and the opening of the <span class="hlt">pores</span> in foam's structure. - Highlights: • Structural characterization of</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/pages/biblio/1415777-importance-filters-microstructure-dynamic-filtration-modeling-gasoline-particulate-filters-gpfs-inhomogeneous-porosity-pore-size-distribution','SCIGOV-DOEP'); return false;" href="https://www.osti.gov/pages/biblio/1415777-importance-filters-microstructure-dynamic-filtration-modeling-gasoline-particulate-filters-gpfs-inhomogeneous-porosity-pore-size-distribution"><span>Importance of filter’s microstructure in dynamic filtration modeling of gasoline particulate filters (GPFs): Inhomogeneous porosity and <span class="hlt">pore</span> size distribution</span></a></p> <p><a target="_blank" href="http://www.osti.gov/pages">DOE PAGES</a></p> <p>Gong, Jian; Stewart, Mark L.; Zelenyuk, Alla; ...</p> <p>2018-01-03</p> <p>The state-of-the-art multiscale modeling of gasoline particulate filter (GPF) including channel scale, wall scale, and <span class="hlt">pore</span> scale is described. The microstructures of two GPFs were experimentally characterized. The <span class="hlt">pore</span> size distributions of the GPFs were determined by mercury porosimetry. The porosity was measured by X-ray computed tomography (CT) and found to be inhomogeneous across the substrate wall. The significance of <span class="hlt">pore</span> size distribution with respect to filtration performance was analyzed. The predictions of filtration efficiency were improved by including the <span class="hlt">pore</span> size distribution in the filtration model. A dynamic heterogeneous multiscale filtration (HMF) model was utilized to simulate particulate filtrationmore » on a single channel particulate filter with realistic particulate emissions from a spark-ignition direct-injection (SIDI) gasoline engine. The dynamic evolution of filter’s microstructure and macroscopic filtration characteristics including mass- and number-based filtration efficiencies and <span class="hlt">pressure</span> drop were predicted and discussed. In conclusion, the microstructure of the GPF substrate including inhomogeneous porosity and <span class="hlt">pore</span> size distribution is found to significantly influence local particulate deposition inside the substrate and macroscopic filtration performance and is recommended to be resolved in the filtration model to simulate and evaluate the filtration performance of GPFs.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/biblio/1415777-importance-filters-microstructure-dynamic-filtration-modeling-gasoline-particulate-filters-gpfs-inhomogeneous-porosity-pore-size-distribution','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/1415777-importance-filters-microstructure-dynamic-filtration-modeling-gasoline-particulate-filters-gpfs-inhomogeneous-porosity-pore-size-distribution"><span>Importance of filter’s microstructure in dynamic filtration modeling of gasoline particulate filters (GPFs): Inhomogeneous porosity and <span class="hlt">pore</span> size distribution</span></a></p> <p><a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a></p> <p>Gong, Jian; Stewart, Mark L.; Zelenyuk, Alla</p> <p></p> <p>The state-of-the-art multiscale modeling of gasoline particulate filter (GPF) including channel scale, wall scale, and <span class="hlt">pore</span> scale is described. The microstructures of two GPFs were experimentally characterized. The <span class="hlt">pore</span> size distributions of the GPFs were determined by mercury porosimetry. The porosity was measured by X-ray computed tomography (CT) and found to be inhomogeneous across the substrate wall. The significance of <span class="hlt">pore</span> size distribution with respect to filtration performance was analyzed. The predictions of filtration efficiency were improved by including the <span class="hlt">pore</span> size distribution in the filtration model. A dynamic heterogeneous multiscale filtration (HMF) model was utilized to simulate particulate filtrationmore » on a single channel particulate filter with realistic particulate emissions from a spark-ignition direct-injection (SIDI) gasoline engine. The dynamic evolution of filter’s microstructure and macroscopic filtration characteristics including mass- and number-based filtration efficiencies and <span class="hlt">pressure</span> drop were predicted and discussed. In conclusion, the microstructure of the GPF substrate including inhomogeneous porosity and <span class="hlt">pore</span> size distribution is found to significantly influence local particulate deposition inside the substrate and macroscopic filtration performance and is recommended to be resolved in the filtration model to simulate and evaluate the filtration performance of GPFs.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/26278641','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26278641"><span><span class="hlt">Pore</span>-forming activity of clostridial binary toxins.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Knapp, O; Benz, R; Popoff, M R</p> <p>2016-03-01</p> <p>Clostridial binary toxins (Clostridium perfringens Iota toxin, Clostridium difficile transferase, Clostridium spiroforme toxin, Clostridium botulinum C2 toxin) as Bacillus binary toxins, including Bacillus anthracis toxins consist of two independent proteins, one being the binding component which mediates the internalization into cell of the intracellularly active component. Clostridial binary toxins induce actin cytoskeleton disorganization through mono-ADP-ribosylation of globular actin and are responsible for enteric diseases. Clostridial and Bacillus binary toxins share structurally and functionally related binding components which recognize specific cell receptors, oligomerize, form <span class="hlt">pores</span> in endocytic vesicle membrane, and mediate the transport of the enzymatic component into the cytosol. Binding components retain the global structure of <span class="hlt">pore</span>-forming toxins (PFTs) from the cholesterol-dependent cytotoxin family such as perfringolysin. However, their <span class="hlt">pore</span>-forming activity notably that of clostridial binding components is more related to that of heptameric PFT family including aerolysin and C. perfringens epsilon toxin. This review focuses upon <span class="hlt">pore</span>-forming activity of clostridial binary toxins compared to other related PFTs. This article is part of a Special Issue entitled: <span class="hlt">Pore</span>-Forming Toxins edited by Mauro Dalla Serra and Franco Gambale. Copyright © 2015 Elsevier B.V. All rights reserved.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=2634367','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=2634367"><span>NUA Activities at the Plant Nuclear <span class="hlt">Pore</span></span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Xu, Xianfeng Morgan; Rose, Annkatrin</p> <p>2007-01-01</p> <p>NUA (Nuclear <span class="hlt">Pore</span> Anchor), the Arabidopsis homolog of Tpr (Translocated Promoter Region), is one of the few nuclear <span class="hlt">pore</span> proteins conserved between animals, yeast and plants. In the May issue of Plant Cell, we report that null mutants of NUA show a pleiotropic, early flowering phenotype accompanied by changes in SUMo and RNA homeostasis. We have shown that the early flowering phenotype is caused by changed abundances of flowering time regulators involved in several pathways. Arabidopsis nua mutants phenocopy mutants lacking the ESD4 (EARlY IN ShoRT DAYS 4) SUMo protease, similar to mutants of their respective yeast homologs. however, in contrast to the comparable yeast mutants, ESD4 does not appear to be delocalized from the nuclear <span class="hlt">pore</span> in nua mutants. Taken together, our experimental data suggests a role for NUA in controlling mRNA export from the nucleus as well as SUMo protease activity at the nuclear <span class="hlt">pore</span>, comparable but not identical to its homologs in other eukaryotes. Furthermore, characterization of NUA illustrates a potential link at the nuclear <span class="hlt">pore</span> between SUMo modification, RNA homeostasis and plant developmental control. PMID:19704557</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=2907898','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=2907898"><span>Development, Fabrication, and Characterization of Hydrogel Based Piezoresistive <span class="hlt">Pressure</span> Sensors with Perforated Diaphragms</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Orthner, M.P.; Buetefisch, Sebastian; Magda, J.; Rieth, L.W.; Solzbacher, F.</p> <p>2010-01-01</p> <p>Hydrogels have been demonstrated to swell in response to a number of external stimuli including pH, CO2, glucose, and ionic strength making them useful for detection of metabolic analytes. To measure hydrogel swelling <span class="hlt">pressure</span>, we have fabricated and tested novel perforated diaphragm piezoresistive <span class="hlt">pressure</span> sensor arrays that couple the <span class="hlt">pressure</span> sensing diaphragm with a perforated semi-permeable membrane. The 2×2 arrays measure approximately 3 × 5 mm2 and consist of four square sensing diaphragms with widths of 1.0, 1.25, and 1.5 mm used to measure full scale <span class="hlt">pressures</span> of 50, 25, and 5 kPa, respectively. An optimized geometry of micro <span class="hlt">pores</span> was etched in silicon diaphragm to allow analyte diffusion into the sensor cavity where the hydrogel material is located. The 14-step front side wafer process was carried out by a commercial foundry service (MSF, Frankfurt (Oder), Germany) and diaphragm <span class="hlt">pores</span> were created using combination of potassium hydroxide (KOH) etching and deep reactive ion etching (DRIE). Sensor characterization was performed (without the use of hydrogels) using a custom bulge testing apparatus that simultaneously measured deflection, <span class="hlt">pressure</span>, and electrical output. Test results are used to quantify the sensor sensitivity and demonstrate proof-of-concept. Simulations showed that the sensitivity was slightly improved for the perforated diaphragm designs while empirical electrical characterization showed that the perforated diaphragm sensors were slightly less sensitive than solid diaphragm sensors. This discrepancy is believed to be due to the influence of compressive stress found within passivation layers and poor etching uniformity. The new perforated diaphragm sensors were fully functional with sensitivities ranging from 23 to 252 μV/V-kPa (FSO= 5 to 80mV), and show a higher nonlinearity at elevated <span class="hlt">pressures</span> than identical sensors with solid diaphragms. Sensors (1.5×1.5 mm2) with perforated diaphragms (<span class="hlt">pores</span>=40 μm) have a nonlinearity of</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://pubs.er.usgs.gov/publication/70035974','USGSPUBS'); return false;" href="https://pubs.er.usgs.gov/publication/70035974"><span>Characterization of the CO2 fluid adsorption in coal as a function of <span class="hlt">pressure</span> using neutron scattering techniques (SANS and USANS)</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Melnichenko, Y.B.; Radlinski, A.P.; Mastalerz, Maria; Cheng, G.; Rupp, J.</p> <p>2009-01-01</p> <p>Small angle neutron scattering techniques have been applied to investigate the phase behavior of CO2 injected into coal and possible changes in the coal <span class="hlt">pore</span> structure that may result from this injection. Three coals were selected for this study: the Seelyville coal from the Illinois Basin (Ro = 0.53%), Baralaba coal from the Bowen Basin (Ro = 0.67%), and Bulli 4 coal from the Sydney Basin (Ro = 1.42%). The coals were selected from different depths to represent the range of the underground CO2 conditions (from subcritical to supercritical) which may be realized in the deep subsurface environment. The experiments were conducted in a high <span class="hlt">pressure</span> cell and CO2 was injected under a range of <span class="hlt">pressure</span> conditions, including those corresponding to in-situ hydrostatic subsurface conditions for each coal. Our experiments indicate that the porous matrix of all coals remains essentially unchanged after exposure to CO2 at <span class="hlt">pressures</span> up to 200??bar (1??bar = 105??Pa). Each coal responds differently to the CO2 exposure and this response appears to be different in <span class="hlt">pores</span> of various sizes within the same coal. For the Seelyville coal at reservoir conditions (16????C, 50??bar), CO2 condenses from a gas into liquid, which leads to increased average fluid density in the <span class="hlt">pores</span> (??<span class="hlt">pore</span>) with sizes (r) 1 ?? 105 ??? r ??? 1 ?? 104???? (??<span class="hlt">pore</span> ??? 0.489??g/cm3) as well as in small <span class="hlt">pores</span> with size between 30 and 300???? (??<span class="hlt">pore</span> ??? 0.671??g/cm3). These values are by a factor of three to four higher than the density of bulk CO2 (??CO2) under similar thermodynamic conditions (??CO2 ??? 0.15??g/cm3). At the same time, in the intermediate size <span class="hlt">pores</span> with r ??? 1000???? the average fluid density is similar to the density of bulk fluid, which indicates that adsorption does not occur in these <span class="hlt">pores</span>. At in situ conditions for the Baralaba coal (35 OC, 100??bar), the average fluid density of CO2 in all <span class="hlt">pores</span> is lower than that of the bulk fluid (??<span class="hlt">pore</span> / ??CO2 ??? 0.6). Neutron scattering from the</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/CFR-2010-title30-vol2/pdf/CFR-2010-title30-vol2-sec250-427.pdf','CFR'); return false;" href="https://www.gpo.gov/fdsys/pkg/CFR-2010-title30-vol2/pdf/CFR-2010-title30-vol2-sec250-427.pdf"><span>30 CFR 250.427 - What are the requirements for <span class="hlt">pressure</span> integrity tests?</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collectionCfr.action?selectedYearFrom=2010&page.go=Go">Code of Federal Regulations, 2010 CFR</a></p> <p></p> <p>2010-07-01</p> <p>... related hole-behavior observations, such as <span class="hlt">pore-pressure</span> test results, gas-cut drilling fluid, and well... integrity tests? 250.427 Section 250.427 Mineral Resources MINERALS MANAGEMENT SERVICE, DEPARTMENT OF THE... Operations Casing and Cementing Requirements § 250.427 What are the requirements for <span class="hlt">pressure</span> integrity tests...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/28091515','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/28091515"><span>Protein crystal nucleation in <span class="hlt">pores</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Nanev, Christo N; Saridakis, Emmanuel; Chayen, Naomi E</p> <p>2017-01-16</p> <p>The most powerful method for protein structure determination is X-ray crystallography which relies on the availability of high quality crystals. Obtaining protein crystals is a major bottleneck, and inducing their nucleation is of crucial importance in this field. An effective method to form crystals is to introduce nucleation-inducing heterologous materials into the crystallization solution. Porous materials are exceptionally effective at inducing nucleation. It is shown here that a combined diffusion-adsorption effect can increase protein concentration inside <span class="hlt">pores</span>, which enables crystal nucleation even under conditions where heterogeneous nucleation on flat surfaces is absent. Provided the <span class="hlt">pore</span> is sufficiently narrow, protein molecules approach its walls and adsorb more frequently than they can escape. The decrease in the nucleation energy barrier is calculated, exhibiting its quantitative dependence on the confinement space and the energy of interaction with the <span class="hlt">pore</span> walls. These results provide a detailed explanation of the effectiveness of porous materials for nucleation of protein crystals, and will be useful for optimal design of such materials.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/biblio/468171-pore-network-model-foam-formation-propagation-porous-media','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/468171-pore-network-model-foam-formation-propagation-porous-media"><span>A <span class="hlt">pore</span>-network model for foam formation and propagation in porous media</span></a></p> <p><a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a></p> <p>Kharabaf, H.; Yortsos, Y.C.</p> <p>1996-12-31</p> <p>We present a <span class="hlt">pore</span>-network model, based on a <span class="hlt">pores</span>-and-throats representation of the porous medium, to simulate the generation and mobilization of foams in porous media. The model allows for various parameters or processes, empirically treated in current models, to be quantified and interpreted. Contrary to previous works, we also consider a dynamic (invasion) in addition to a static process. We focus on the properties of the displacement, the onset of foam flow and mobilization, the foam texture and the sweep efficiencies obtained. The model simulates an invasion process, in which gas invades a porous medium occupied by a surfactant solution.more » The controlling parameter is the snap-off probability, which in turn determines the foam quality for various size distributions of <span class="hlt">pores</span> and throats. For the front to advance, the applied <span class="hlt">pressure</span> gradient needs to be sufficiently high to displace a series of lamellae along a minimum capillary resistance (threshold) path. We determine this path using a novel algorithm. The fraction of the flowing lamellae, X{sub f} (and, consequently, the fraction of the trapped lamellae, X{sub f}) which are currently empirical, are also calculated. The model allows the delineation of conditions tinder which high-quality (strong) or low-quality (weak) foams form. In either case, the sweep efficiencies in displacements in various media are calculated. In particular, the invasion by foam of low permeability layers during injection in a heterogeneous system is demonstrated.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20050203864','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20050203864"><span>Capillary <span class="hlt">Pressure</span> of a Liquid Between Uniform Spheres Arranged in a Square-Packed Layer</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Alexader, J. Iwan D.; Slobozhanin, Lev A.; Collicott, Steven H.</p> <p>2004-01-01</p> <p>The capillary <span class="hlt">pressure</span> in the <span class="hlt">pores</span> defined by equidimensional close-packed spheres is analyzed numerically. In the absence of gravity the menisci shapes are constructed using Surface Evolver code. This permits calculation the free surface mean curvature and hence the capillary <span class="hlt">pressure</span>. The dependences of capillary <span class="hlt">pressure</span> on the liquid volume constructed here for a set of contact angles allow one to determine the evolution of basic capillary characteristics under quasi-static infiltration and drainage. The maximum <span class="hlt">pressure</span> difference between liquid and gas required for a meniscus passing through a <span class="hlt">pore</span> is calculated and compared with that for hexagonal packing and with approximate solution given by Mason and Morrow [l]. The lower and upper critical liquid volumes that determine the stability limits for the equilibrium capillary liquid in contact with square packed array of spheres are tabulated for a set of contact angles.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017AdWR..104..105G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017AdWR..104..105G"><span>Upscaling soil saturated hydraulic conductivity from <span class="hlt">pore</span> throat characteristics</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ghanbarian, Behzad; Hunt, Allen G.; Skaggs, Todd H.; Jarvis, Nicholas</p> <p>2017-06-01</p> <p>Upscaling and/or estimating saturated hydraulic conductivity Ksat at the core scale from microscopic/macroscopic soil characteristics has been actively under investigation in the hydrology and soil physics communities for several decades. Numerous models have been developed based on different approaches, such as the bundle of capillary tubes model, pedotransfer functions, etc. In this study, we apply concepts from critical path analysis, an upscaling technique first developed in the physics literature, to estimate saturated hydraulic conductivity at the core scale from microscopic <span class="hlt">pore</span> throat characteristics reflected in capillary <span class="hlt">pressure</span> data. With this new model, we find Ksat estimations to be within a factor of 3 of the average measured saturated hydraulic conductivities reported by Rawls et al. (1982) for the eleven USDA soil texture classes.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19780062895&hterms=Micropore&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3DMicropore','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19780062895&hterms=Micropore&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3DMicropore"><span>Water vapor weathering of Taurus-Littrow orange soil - A <span class="hlt">pore</span>-structure analysis</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Cadenhead, D. A.; Mikhail, R. S.</p> <p>1975-01-01</p> <p>A <span class="hlt">pore</span>-volume analysis was performed on water vapor adsorption data previously obtained on a fresh sample of Taurus-Littrow orange soil, and the analysis was repeated on the same sample after its exposure to moist air for a period of approximately six months. The results indicate that exposure of an outgassed sample to high relative <span class="hlt">pressures</span> of water vapor can result in the formation of substantial micropore structure, the precise amount being dependent on the sample pretreatment, particularly the outgassing temperature. Micropore formation is explained in terms of water penetration into surface defects. In contrast, long-term exposure to moist air at low relative <span class="hlt">pressures</span> appears to reverse the process with the elimination of micropores and enlargement of mesopores possibly through surface diffusion of metastable adsorbent material. The results are considered with reference to the storage of lunar samples.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016Nanos...813045M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016Nanos...813045M"><span>pH controlled gating of toxic protein <span class="hlt">pores</span> by dendrimers</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Mandal, Taraknath; Kanchi, Subbarao; Ayappa, K. G.; Maiti, Prabal K.</p> <p>2016-06-01</p> <p>Designing effective nanoscale blockers for membrane inserted <span class="hlt">pores</span> formed by <span class="hlt">pore</span> forming toxins, which are expressed by several virulent bacterial strains, on a target cell membrane is a challenging and active area of research. Here we demonstrate that PAMAM dendrimers can act as effective pH controlled gating devices once the <span class="hlt">pore</span> has been formed. We have used fully atomistic molecular dynamics (MD) simulations to characterize the cytolysin A (ClyA) protein <span class="hlt">pores</span> modified with fifth generation (G5) PAMAM dendrimers. Our results show that the PAMAM dendrimer, in either its protonated (P) or non-protonated (NP) states can spontaneously enter the protein lumen. Protonated dendrimers interact strongly with the negatively charged protein <span class="hlt">pore</span> lumen. As a consequence, P dendrimers assume a more expanded configuration efficiently blocking the <span class="hlt">pore</span> when compared with the more compact configuration adopted by the neutral NP dendrimers creating a greater void space for the passage of water and ions. To quantify the effective blockage of the protein <span class="hlt">pore</span>, we have calculated the <span class="hlt">pore</span> conductance as well as the residence times by applying a weak force on the ions/water. Ionic currents are reduced by 91% for the P dendrimers and 31% for the NP dendrimers. The preferential binding of Cl- counter ions to the P dendrimer creates a zone of high Cl- concentration in the vicinity of the internalized dendrimer and a high concentration of K+ ions in the transmembrane region of the <span class="hlt">pore</span> lumen. In addition to steric effects, this induced charge segregation for the P dendrimer effectively blocks ionic transport through the <span class="hlt">pore</span>. Our investigation shows that the bio-compatible PAMAM dendrimers can potentially be used to develop therapeutic protocols based on the pH sensitive gating of <span class="hlt">pores</span> formed by <span class="hlt">pore</span> forming toxins to mitigate bacterial infections.Designing effective nanoscale blockers for membrane inserted <span class="hlt">pores</span> formed by <span class="hlt">pore</span> forming toxins, which are expressed by several virulent</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/26474001','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26474001"><span>Acarbose, the α-glucosidase inhibitor, attenuates the blood <span class="hlt">pressure</span> and splanchnic blood flow responses to meal in elderly patients with postprandial hypotension concomitant with <span class="hlt">abnormal</span> glucose metabolism.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Qiao, Wei; Li, Jing; Li, Ying; Qian, Duan; Chen, Lei; Wei, Xiansen; Jin, Jiangli; Wang, Yong</p> <p>2016-02-01</p> <p>Postprandial hypotension (PPH) is a unique clinical phenomenon in the elderly, but its underlying pathogenesis has not been completely elucidated, and drug treatment is still in clinical exploratory stage. The aim of the study was to evaluate the relationship between the fall in postprandial blood <span class="hlt">pressure</span> and splanchnic blood flow, and to provide a theoretical basis for the treatment of PPH by taking acarbose. The study included 20 elderly inpatients diagnosed with PPH concomitant with <span class="hlt">abnormal</span> glucose metabolism at stable condition. They were treated with 50 mg acarbose with their meal to observe the changes in blood <span class="hlt">pressure</span>, heart rate, and blood glucose level, and to monitor the hemodynamics of the superior mesenteric artery (SMA) before and after treatment. Without acarbose treatment, patients after a meal had significantly decreased systolic and diastolic blood <span class="hlt">pressure</span>, faster postprandial heart rate, higher postprandial glucose level at each period, and increased postprandial SMA blood flow compared with that at fasting state (P<0.05). Acarbose treatment significantly attenuated the decrease of postprandial systolic blood <span class="hlt">pressures</span> from 35.50±12.66 to 22.25±6.90 mmHg (P=0.000), the increase of heart rate from 9.67±5.94 to 5.33±3.20 beats/min (P=0.016), the increase of postprandial blood glucose from 3.55±1.69 to 2.28±1.61 mmol/l (P=0.000), the increase of postprandial SMA blood flow from 496.80±147.15 to 374.55±97.89 ml/min (P=0.031), and the incidence of PPH, syncope, falls, dizziness, weakness, and angina pectoris (P<0.05). The maximal decrease of postprandial systolic blood <span class="hlt">pressure</span> was positively associated with the maximal increase in postprandial SMA blood flow (r=0.351, P=0.026). Acarbose treatment showed no significant side effects. The increase in postprandial splanchnic perfusion is one of the reasons for PPH formation. Acarbose may exert its role in PPH treatment by reducing postprandial gastrointestinal blood perfusion. Giving</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016AGUFM.H51B1464H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016AGUFM.H51B1464H"><span><span class="hlt">Pore</span>-scale observation and 3D simulation of wettability effects on supercritical CO2 - brine immiscible displacement in drainage</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Hu, R.; Wan, J.; Chen, Y.</p> <p>2016-12-01</p> <p>Wettability is a factor controlling the fluid-fluid displacement pattern in porous media and significantly affects the flow and transport of supercritical (sc) CO2 in geologic carbon sequestration. Using a high-<span class="hlt">pressure</span> micromodel-microscopy system, we performed drainage experiments of scCO2 invasion into brine-saturated water-wet and intermediate-wet micromodels; we visualized the scCO2 invasion morphology at <span class="hlt">pore</span>-scale under reservoir conditions. We also performed <span class="hlt">pore</span>-scale numerical simulations of the Navier-Stokes equations to obtain 3D details of fluid-fluid displacement processes. Simulation results are qualitatively consistent with the experiments, showing wider scCO2 fingering, higher percentage of scCO2 and more compact displacement pattern in intermediate-wet micromodel. Through quantitative analysis based on <span class="hlt">pore</span>-scale simulation, we found that the reduced wettability reduces the displacement front velocity, promotes the <span class="hlt">pore</span>-filling events in the longitudinal direction, delays the breakthrough time of invading fluid, and then increases the displacement efficiency. Simulated results also show that the fluid-fluid interface area follows a unified power-law relation with scCO2 saturation, and show smaller interface area in intermediate-wet case which suppresses the mass transfer between the phases. These <span class="hlt">pore</span>-scale results provide insights for the wettability effects on CO2 - brine immiscible displacement in geologic carbon sequestration.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li class="active"><span>23</span></li> <li><a href="#" onclick='return showDiv("page_24");'>24</a></li> <li><a href="#" onclick='return showDiv("page_25");'>25</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_23 --> <div id="page_24" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li class="active"><span>24</span></li> <li><a href="#" onclick='return showDiv("page_25");'>25</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="461"> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5391558','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5391558"><span>Tailoring <span class="hlt">Pore</span> Size and Chemical Interior of near 1 nm Sized <span class="hlt">Pores</span> in a Nanoporous Polymer Based on a Discotic Liquid Crystal</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p></p> <p>2017-01-01</p> <p>A triazine based disc shaped molecule with two hydrolyzable units, imine and ester groups, was polymerized via acyclic diene metathesis in the columnar hexagonal (Colhex) LC phase. Fabrication of a cationic nanoporous polymer (<span class="hlt">pore</span> diameter ∼1.3 nm) lined with ammonium groups at the <span class="hlt">pore</span> surface was achieved by hydrolysis of the imine linkage. Size selective aldehyde uptake by the cationic porous polymer was demonstrated. The anilinium groups in the <span class="hlt">pores</span> were converted to azide as well as phenyl groups by further chemical treatment, leading to porous polymers with neutral functional groups in the <span class="hlt">pores</span>. The <span class="hlt">pores</span> were enlarged by further hydrolysis of the ester groups to create ∼2.6 nm <span class="hlt">pores</span> lined with −COONa surface groups. The same <span class="hlt">pores</span> could be obtained in a single step without first hydrolyzing the imine linkage. XRD studies demonstrated that the Colhex order of the monomer was preserved after polymerization as well as in both the nanoporous polymers. The porous anionic polymer lined with −COOH groups was further converted to the −COOLi, −COONa, −COOK, −COOCs, and −COONH4 salts. The porous polymer lined with −COONa groups selectively adsorbs a cationic dye, methylene blue, over an anionic dye. PMID:28416888</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/23831588','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/23831588"><span>Healing kinetics of microneedle-formed <span class="hlt">pores</span> in PLGA films.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Mazzara, J M; Balagna, M A; Thouless, M D; Schwendeman, S P</p> <p>2013-10-28</p> <p>The spontaneous healing of aqueous <span class="hlt">pores</span> in poly(D,L-lactic-co-glycolic acid) (PLGA) drug delivery systems has been identified to play a key role in terminating the burst release of large molecules, and to provide a means for novel aqueous-based microencapsulation. To examine healing of PLGA, <span class="hlt">pores</span> were created of defined size and depth on the surface of thin PLGA films by stamping with blunt-tip microneedles. <span class="hlt">Pore</span> dimensions on the micron-scale were relevant to surface <span class="hlt">pores</span> of common PLGA microspheres and could be easily monitored by light microscopy. Most <span class="hlt">pores</span> healed reproducibly at temperatures above the glass-transition temperature (T(g)) of the films, with healing times decreasing sharply with increasing temperature according to Williams-Landel-Ferry (WLF) behavior. It is suggested that healing is driven by high surface tension in the films and occurs through viscoelastic creep. Hydrated films healed at lower temperatures than dry films, consistent with a drop in Tg upon polymer hydration. Larger <span class="hlt">pores</span> took longer to heal than smaller ones, while <span class="hlt">pores</span> larger than 20 μm did not heal before significant polymer degradation occurred. Films of a less hydrophobic PLGA showed slower healing kinetics, attributed to a weaker surface tension driving force. Deeper <span class="hlt">pores</span> showed signs of in-plane stress from spin-coating, and either ruptured or only partially healed when incubated wet and dry, respectively. © 2013.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013WRR....49.1943R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013WRR....49.1943R"><span>Saturation-dependent solute dispersivity in porous media: <span class="hlt">Pore</span>-scale processes</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Raoof, A.; Hassanizadeh, S. M.</p> <p>2013-04-01</p> <p>It is known that in variably saturated porous media, dispersion coefficient depends on Darcy velocity and water saturation. In one-dimensional flow, it is commonly assumed that the dispersion coefficient is a linear function of velocity. The coefficient of proportionality, called the dispersivity, is considered to depend on saturation. However, there is not much known about its dependence on saturation. In this study, we investigate, using a <span class="hlt">pore</span> network model, how the longitudinal dispersivity varies nonlinearly with saturation. We schematize the porous medium as a network of <span class="hlt">pore</span> bodies and <span class="hlt">pore</span> throats with finite volumes. The <span class="hlt">pore</span> space is modeled using the multidirectional <span class="hlt">pore</span>-network concept, which allows for a distribution of <span class="hlt">pore</span> coordination numbers. This topological property together with the distribution of <span class="hlt">pore</span> sizes are used to mimic the microstructure of real porous media. The dispersivity is calculated by solving the mass balance equations for solute concentration in all network elements and averaging the concentrations over a large number of <span class="hlt">pores</span>. We have introduced a new formulation of solute transport within <span class="hlt">pore</span> space, where we account for different compartments of residual water within drained <span class="hlt">pores</span>. This formulation makes it possible to capture the effect of limited mixing due to partial filling of the <span class="hlt">pores</span> under variably saturated conditions. We found that dispersivity increases with the decrease in saturation, it reaches a maximum value, and then decreases with further decrease in saturation. To show the capability of our formulation to properly capture the effect of saturation on solute dispersion, we applied it to model the results of a reported experimental study.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017JGRB..122.3410C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017JGRB..122.3410C"><span><span class="hlt">Pore</span>-scale modeling of hydromechanical coupled mechanics in hydrofracturing process</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Chen, Zhiqiang; Wang, Moran</p> <p>2017-05-01</p> <p>Hydrofracturing is an important technique in petroleum industry to stimulate well production. Yet the mechanism of induced fracture growth is still not fully understood, which results in some unsatisfactory wells even with hydrofracturing treatments. In this work we establish a more accurate numerical framework for hydromechanical coupling, where the solid deformation and fracturing are modeled by discrete element method and the fluid flow is simulated directly by lattice Boltzmann method at <span class="hlt">pore</span> scale. After validations, hydrofracturing is simulated with consideration on the strength heterogeneity effects on fracture geometry and microfailure mechanism. A modified topological index is proposed to quantify the complexity of fracture geometry. The results show that strength heterogeneity has a significant influence on hydrofracturing. In heterogeneous samples, the fracturing behavior is crack nucleation around the tip of fracture and connection of it to the main fracture, which is usually accompanied by shear failure. However, in homogeneous ones the fracture growth is achieved by the continuous expansion of the crack, where the tensile failure often dominates. It is the fracturing behavior that makes the fracture geometry in heterogeneous samples much more complex than that in homogeneous ones. In addition, higher <span class="hlt">pore</span> <span class="hlt">pressure</span> leads to more shear failure events for both heterogeneous and homogeneous samples.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017ACP....17.1595M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017ACP....17.1595M"><span>Pre-activation of aerosol particles by ice preserved in <span class="hlt">pores</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Marcolli, Claudia</p> <p>2017-02-01</p> <p>Pre-activation denotes the capability of particles or materials to nucleate ice at lower relative humidities or higher temperatures compared to their intrinsic ice nucleation efficiency after having experienced an ice nucleation event or low temperature before. This review presumes that ice preserved in <span class="hlt">pores</span> is responsible for pre-activation and analyses pre-activation under this presumption. Idealized trajectories of air parcels are used to discuss the <span class="hlt">pore</span> characteristics needed for ice to persist in <span class="hlt">pores</span> and to induce macroscopic ice growth out of the <span class="hlt">pores</span>. The <span class="hlt">pore</span> width needed to keep <span class="hlt">pores</span> filled with water decreases with decreasing relative humidity as described by the inverse Kelvin equation. Thus, narrow <span class="hlt">pores</span> remain filled with ice well below ice saturation. However, the smaller the <span class="hlt">pore</span> width, the larger the melting and freezing point depressions within the <span class="hlt">pores</span>. Therefore, pre-activation due to <span class="hlt">pore</span> ice is constrained by the melting of ice in narrow <span class="hlt">pores</span> and the sublimation of ice from wide <span class="hlt">pores</span> imposing restrictions on the temperature and relative humidity range of pre-activation for cylindrical <span class="hlt">pores</span>. Ice is better protected in ink-bottle-shaped <span class="hlt">pores</span> with a narrow opening leading to a large cavity. However, whether pre-activation is efficient also depends on the capability of ice to grow macroscopically, i.e. out of the <span class="hlt">pore</span>. A strong effect of pre-activation is expected for swelling <span class="hlt">pores</span>, because at low relative humidity (RH) their openings narrow and protect the ice within them against sublimation. At high relative humidities, they open up and the ice can grow to macroscopic size and form an ice crystal. Similarly, ice protected in pockets is perfectly sheltered against sublimation but needs the dissolution of the surrounding matrix to be effective. <span class="hlt">Pores</span> partially filled with condensable material may also show pre-activation. In this case, complete filling occurs at lower RH than for empty <span class="hlt">pores</span> and freezing shifts to lower temperatures</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015EGUGA..17.9215G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015EGUGA..17.9215G"><span>The <span class="hlt">pore</span> space scramble</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Gormally, Alexandra; Bentham, Michelle; Vermeylen, Saskia; Markusson, Nils</p> <p>2015-04-01</p> <p>Climate change and energy security continue to be the context of the transition to a secure, affordable and low carbon energy future, both in the UK and beyond. This is reflected in for example, binding climate policy targets at the EU level, the introduction of renewable energy targets, and has also led to an increasing interest in Carbon Capture and Storage (CCS) technology with its potential to help mitigate against the effects of CO2 emissions from fossil fuel burning. The UK has proposed a three phase strategy to integrate CCS into its energy system in the long term focussing on off-shore subsurface storage (DECC, 2014). The potential of CCS therefore, raises a number of challenging questions and issues surrounding the long-term storage of CO2 captured and injected into underground spaces and, alongside other novel uses of the subsurface, contributes to opening a new field for discussion on the governance of the subsurface. Such 'novel' uses of the subsurface have lead to it becoming an increasingly contested space in terms of its governance, with issues emerging around the role of ownership, liability and property rights of subsurface <span class="hlt">pore</span> space. For instance, questions over the legal ownership of <span class="hlt">pore</span> space have arisen with ambiguity over the legal standpoint of the surface owner and those wanting to utilise the <span class="hlt">pore</span> space for gas storage, and suggestions of whether there are depths at which legal 'ownership' becomes obsolete (Barton, 2014). Here we propose to discuss this '<span class="hlt">pore</span> space scramble' and provide examples of the competing trajectories of different stakeholders, particularly in the off-shore context given its priority in the UK. We also propose to highlight the current ambiguity around property law of <span class="hlt">pore</span> space in the UK with reference to approaches currently taken in different national contexts. Ultimately we delineate contrasting models of governance to illustrate the choices we face and consider the ethics of these models for the common good</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/12885646','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/12885646"><span>The <span class="hlt">pressure</span>-dependence of the size of extruded vesicles.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Patty, Philipus J; Frisken, Barbara J</p> <p>2003-08-01</p> <p>Variations in the size of vesicles formed by extrusion through small <span class="hlt">pores</span> are discussed in terms of a simple model. Our model predicts that the radius should decrease as the square root of the applied <span class="hlt">pressure</span>, consistent with data for vesicles extruded under various conditions. The model also predicts dependencies on the <span class="hlt">pore</span> size used and on the lysis tension of the vesicles being extruded that are consistent with our data. The <span class="hlt">pore</span> size was varied by using track-etched polycarbonate membranes with average <span class="hlt">pore</span> diameters ranging from 50 to 200 nm. To vary the lysis tension, vesicles made from POPC (1-palmitoyl-2-oleoyl-sn-glycero-3-phosphatidylcholine), mixtures of POPC and cholesterol, and mixtures of POPC and C(16)-ceramide were studied. The lysis tension, as measured by an extrusion-based technique, of POPC:cholesterol vesicles is higher than that of pure POPC vesicles whereas POPC:ceramide vesicles have lower lysis tensions than POPC vesicles.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=1303220','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=1303220"><span>The <span class="hlt">Pressure</span>-Dependence of the Size of Extruded Vesicles</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Patty, Philipus J.; Frisken, Barbara J.</p> <p>2003-01-01</p> <p>Variations in the size of vesicles formed by extrusion through small <span class="hlt">pores</span> are discussed in terms of a simple model. Our model predicts that the radius should decrease as the square root of the applied <span class="hlt">pressure</span>, consistent with data for vesicles extruded under various conditions. The model also predicts dependencies on the <span class="hlt">pore</span> size used and on the lysis tension of the vesicles being extruded that are consistent with our data. The <span class="hlt">pore</span> size was varied by using track-etched polycarbonate membranes with average <span class="hlt">pore</span> diameters ranging from 50 to 200 nm. To vary the lysis tension, vesicles made from POPC (1-palmitoyl-2-oleoyl-sn-glycero-3-phosphatidylcholine), mixtures of POPC and cholesterol, and mixtures of POPC and C16-ceramide were studied. The lysis tension, as measured by an extrusion-based technique, of POPC:cholesterol vesicles is higher than that of pure POPC vesicles whereas POPC:ceramide vesicles have lower lysis tensions than POPC vesicles. PMID:12885646</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016JMPSo..88..227R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016JMPSo..88..227R"><span>A characterization of the coupled evolution of grain fabric and <span class="hlt">pore</span> space using complex networks: <span class="hlt">Pore</span> connectivity and optimized flows in the presence of shear bands</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Russell, Scott; Walker, David M.; Tordesillas, Antoinette</p> <p>2016-03-01</p> <p>A framework for the multiscale characterization of the coupled evolution of the solid grain fabric and its associated <span class="hlt">pore</span> space in dense granular media is developed. In this framework, a pseudo-dual graph transformation of the grain contact network produces a graph of <span class="hlt">pores</span> which can be readily interpreted as a <span class="hlt">pore</span> space network. Survivability, a new metric succinctly summarizing the connectivity of the solid grain and <span class="hlt">pore</span> space networks, measures material robustness. The size distribution and the connectivity of <span class="hlt">pores</span> can be characterized quantitatively through various network properties. Assortativity characterizes the <span class="hlt">pore</span> space with respect to the parity of the number of particles enclosing the <span class="hlt">pore</span>. Multiscale clusters of odd parity versus even parity contact cycles alternate spatially along the shear band: these represent, respectively, local jamming and unjamming regions that continually switch positions in time throughout the failure regime. Optimal paths, established using network shortest paths in favor of large <span class="hlt">pores</span>, provide clues on preferential paths for interstitial matter transport. In systems with higher rolling resistance at contacts, less tortuous shortest paths thread through larger <span class="hlt">pores</span> in shear bands. Notably the structural patterns uncovered in the <span class="hlt">pore</span> space suggest that more robust models of interstitial <span class="hlt">pore</span> flow through deforming granular systems require a proper consideration of the evolution of in situ shear band and fracture patterns - not just globally, but also inside these localized failure zones.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016AGUFM.H51O..03K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016AGUFM.H51O..03K"><span><span class="hlt">Pore</span>-scale modeling of moving contact line problems in immiscible two-phase flow.</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kucala, A.; Noble, D.; Martinez, M. J.</p> <p>2016-12-01</p> <p>Two immiscible fluids in static equilibrium form a common interface along a solid surface, characterized as the static contact (wetting) angle and is a function of surface geometry, intermolecular forces, and interfacial surface energies manifested as interfacial tension. This static configuration may become perturbed due to external force imbalances (mass injection, <span class="hlt">pressure</span> gradients, buoyancy, etc.) and the contact line location and interface curvature becomes dynamic. Accurate modeling of moving contact line (MCL) problems is imperative in predicting capillary <span class="hlt">pressure</span> vs. saturation curves, permeability, and preferential flow paths for a variety of applications, including geological carbon storage (GCS) and enhanced oil recovery (EOR). Here, we present a model for the moving contact line using <span class="hlt">pore</span>-scale computational fluid dynamics (CFD) which solves the full, time-dependent Navier-Stokes equations using the Galerkin finite-element method. The MCL is modeled as a surface traction force proportional to the surface tension, dependent on the static properties of the immiscible fluid/solid system. The moving two-phase interface is tracked using the level set method and discretized with the conformal decomposition finite element method (CDFEM), allowing for surface tension effects to be computed at the exact interface location. We present a variety of verification test cases for simple two- and three-dimensional geometries to validate the current model, including threshold <span class="hlt">pressure</span> predictions in flows through <span class="hlt">pore</span>-throats for a variety of wetting angles. Simulations involving more complex geometries are also presented to be used in future simulations for GCS and EOR problems. Sandia is a multiprogram laboratory operated by Sandia Corporation, a Lockheed Martin Company, for the United States Department of Energy's National Nuclear Security Administration under contract DE-AC04-94AL85000</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3907245','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3907245"><span>Atomistic Simulations of <span class="hlt">Pore</span> Formation and Closure in Lipid Bilayers</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Bennett, W. F. Drew; Sapay, Nicolas; Tieleman, D. Peter</p> <p>2014-01-01</p> <p>Cellular membranes separate distinct aqueous compartments, but can be breached by transient hydrophilic <span class="hlt">pores</span>. A large energetic cost prevents <span class="hlt">pore</span> formation, which is largely dependent on the composition and structure of the lipid bilayer. The softness of bilayers and the disordered structure of <span class="hlt">pores</span> make their characterization difficult. We use molecular-dynamics simulations with atomistic detail to study the thermodynamics, kinetics, and mechanism of <span class="hlt">pore</span> formation and closure in DLPC, DMPC, and DPPC bilayers, with <span class="hlt">pore</span> formation free energies of 17, 45, and 78 kJ/mol, respectively. By using atomistic computer simulations, we are able to determine not only the free energy for <span class="hlt">pore</span> formation, but also the enthalpy and entropy, which yields what is believed to be significant new insights in the molecular driving forces behind membrane defects. The free energy cost for <span class="hlt">pore</span> formation is due to a large unfavorable entropic contribution and a favorable change in enthalpy. Changes in hydrogen bonding patterns occur, with increased lipid-water interactions, and fewer water-water hydrogen bonds, but the total number of overall hydrogen bonds is constant. Equilibrium <span class="hlt">pore</span> formation is directly observed in the thin DLPC lipid bilayer. Multiple long timescale simulations of <span class="hlt">pore</span> closure are used to predict <span class="hlt">pore</span> lifetimes. Our results are important for biological applications, including the activity of antimicrobial peptides and a better understanding of membrane protein folding, and improve our understanding of the fundamental physicochemical nature of membranes. PMID:24411253</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018JGRB..123.1072K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018JGRB..123.1072K"><span>Changes in Physical Properties of the Nankai Trough Megasplay Fault Induced by Earthquakes, Detected by Continuous <span class="hlt">Pressure</span> Monitoring</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kinoshita, C.; Saffer, D.; Kopf, A.; Roesner, A.; Wallace, L. M.; Araki, E.; Kimura, T.; Machida, Y.; Kobayashi, R.; Davis, E.; Toczko, S.; Carr, S.</p> <p>2018-02-01</p> <p>One primary objective of Integrated Ocean Drilling Program Expedition 365, conducted as part of the Nankai Trough Seismogenic Zone Experiment, was to recover a temporary observatory emplaced to monitor formation <span class="hlt">pore</span> fluid <span class="hlt">pressure</span> and temperature within a splay fault in the Nankai subduction zone offshore SW Honshu, Japan. Here we use a 5.3 year time series of formation <span class="hlt">pore</span> fluid <span class="hlt">pressure</span>, and in particular the response to ocean tidal loading, to evaluate changes in <span class="hlt">pore</span> <span class="hlt">pressure</span> and formation and fluid elastic properties induced by earthquakes. Our analysis reveals 31 earthquake-induced perturbations. These are dominantly characterized by small transient increases in <span class="hlt">pressure</span> (28 events) and decreases in ocean tidal loading efficiency (14 events) that reflect changes to formation or fluid compressibility. The observed perturbations follow a magnitude-distance threshold similar to that reported for earthquake-driven hydrological effects in other settings. To explore the mechanisms that cause these changes, we evaluate the expected static and dynamic strains from each earthquake. The expected static strains are too small to explain the observed <span class="hlt">pressure</span> changes. In contrast, estimated dynamic strains correlate with the magnitude of changes in both <span class="hlt">pressure</span> and loading efficiency. We propose potential mechanism for the changes and subsequent recovery, which is exsolution of dissolved gas in interstitial fluids in response to shaking.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017EGUGA..1913012W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017EGUGA..1913012W"><span>Analogue modelling of caprock failure and sediment mobilisation due to <span class="hlt">pore</span> fluid overpressure in shallow reservoirs</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Warsitzka, Michael; Kukowski, Nina; May, Franz</p> <p>2017-04-01</p> <p>Injection of CO2 in geological formations may cause excess <span class="hlt">pore</span> fluid <span class="hlt">pressure</span> by enhancing the fluid volume in the reservoir rock and by buoyancy-driven flow. If sediments in the reservoir and the caprock are undercompacted, <span class="hlt">pore</span> fluid overpressure can lead to hydro-fractures in the caprock and fluidisation of sediments. Eventually, these processes trigger the formation of pipe structures, gas chimneys, gas domes or sand injections. Generally, such structures serve as high permeable pathways for fluid migration through a low-permeable seal layer and have to be considered in risk assessment or modelling of caprock integrity of CO2 storage sites. We applied scaled analogue experiments to characterise and quantify mechanisms determining the onset and migration of hydro-fractures in a low-permeable, cohesive caprock and fluidisation of unconsolidated sediments of the reservoir layer. The caprock is simulated by different types of cohesive powder. The reservoir layer consists of granulates with small particle density. Air injected through the base of the experiment and additionally through a single needle valve reaching into the analogue material is applied to generate fluid <span class="hlt">pressure</span> within the materials. With this procedure, regional fluid <span class="hlt">pressure</span> increase or a point-like local fluid <span class="hlt">pressure</span> increase (e.g. injection well), respectively, can be simulated. The deformation in the analogue materials is analysed with a particle tracking imaging velocimetry technique. <span class="hlt">Pressure</span> sensors at the base of the experiment and in the needle valve record the air <span class="hlt">pressure</span> during an experimental run. The structural evolution observed in the experiments reveal that the cohesive cap rock first forms a dome-like anticline. Extensional fractures occur at the hinges of the anticline. A further increase of fluid <span class="hlt">pressure</span> causes a migration of this fractures towards the surface, which is followed by intrusion of reservoir material into the fractures and the collapse of the anticline. The</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017CG.....98....1B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017CG.....98....1B"><span>Variational-based segmentation of bio-<span class="hlt">pores</span> in tomographic images</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Bauer, Benjamin; Cai, Xiaohao; Peth, Stephan; Schladitz, Katja; Steidl, Gabriele</p> <p>2017-01-01</p> <p>X-ray computed tomography (CT) combined with a quantitative analysis of the resulting volume images is a fruitful technique in soil science. However, the variations in X-ray attenuation due to different soil components keep the segmentation of single components within these highly heterogeneous samples a challenging problem. Particularly demanding are bio-<span class="hlt">pores</span> due to their elongated shape and the low gray value difference to the surrounding soil structure. Recently, variational models in connection with algorithms from convex optimization were successfully applied for image segmentation. In this paper we apply these methods for the first time for the segmentation of bio-<span class="hlt">pores</span> in CT images of soil samples. We introduce a novel convex model which enforces smooth boundaries of bio-<span class="hlt">pores</span> and takes the varying attenuation values in the depth into account. Segmentation results are reported for different real-world 3D data sets as well as for simulated data. These results are compared with two gray value thresholding methods, namely indicator kriging and a global thresholding procedure, and with a morphological approach. Pros and cons of the methods are assessed by considering geometric features of the segmented bio-<span class="hlt">pore</span> systems. The variational approach features well-connected smooth <span class="hlt">pores</span> while not detecting smaller or shallower <span class="hlt">pores</span>. This is an advantage in cases where the main bio-<span class="hlt">pores</span> network is of interest and where infillings, e.g., excrements of earthworms, would result in losing <span class="hlt">pore</span> connections as observed for the other thresholding methods.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017EGUGA..1916923D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017EGUGA..1916923D"><span>Deposition Nucleation or <span class="hlt">Pore</span> Condensation and Freezing?</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>David, Robert O.; Mahrt, Fabian; Marcolli, Claudia; Fahrni, Jonas; Brühwiler, Dominik; Lohmann, Ulrike; Kanji, Zamin A.</p> <p>2017-04-01</p> <p>Ice nucleation plays an important role in moderating Earth's climate and precipitation formation. Over the last century of research, several mechanisms for the nucleation of ice have been identified. Of the known mechanisms for ice nucleation, only deposition nucleation occurs below water saturation. Deposition nucleation is defined as the formation of ice from supersaturated water vapor on an insoluble particle without the prior formation of liquid. However, recent work has found that the efficiency of so-called deposition nucleation shows a dependence on the homogeneous freezing temperature of water even though no liquid phase is presumed to be present. Additionally, the ability of certain particles to nucleate ice more efficiently after being pre-cooled (pre-activation) raises questions on the true mechanism when ice nucleation occurs below water saturation. In an attempt to explain the dependence of the efficiency of so-called deposition nucleation on the onset of homogeneous freezing of liquid water, <span class="hlt">pore</span> condensation and freezing has been proposed. <span class="hlt">Pore</span> condensation and freezing suggests that the liquid phase can exist under sub-saturated conditions with respect to liquid in narrow confinements or <span class="hlt">pores</span> due to the inverse Kelvin effect. Once the liquid-phase condenses, it is capable of nucleating ice either homogeneously or heterogeneously. The role of <span class="hlt">pore</span> condensation and freezing is assessed in the Zurich Ice Nucleation Chamber, a continuous flow diffusion chamber, using spherical nonporous and mesoporous silica particles. The mesoporous silica particles have a well-defined particle size range of 400 to 600nm with discreet <span class="hlt">pore</span> sizes of 2.5, 2.8, 3.5 and 3.8nm. Experiments conducted between 218K and 238K show that so-called deposition nucleation only occurs below the homogenous freezing temperature of water and is highly dependent on the presence of <span class="hlt">pores</span> and their size. The results strongly support <span class="hlt">pore</span> condensation and freezing, questioning the role of</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4873789','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4873789"><span>Temperature-mediated phase transformation, <span class="hlt">pore</span> geometry and <span class="hlt">pore</span> hysteresis transformation of borohydride derived in-born porous zirconium hydroxide nanopowders</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Nayak, Nadiya B.; Nayak, Bibhuti B.</p> <p>2016-01-01</p> <p>Development of in-born porous nature of zirconium hydroxide nanopowders through a facile hydrogen (H2) gas-bubbles assisted borohydride synthesis route using sodium borohydride (NaBH4) and novel information on the temperature-mediated phase transformation, <span class="hlt">pore</span> geometry as well as <span class="hlt">pore</span> hysteresis transformation of in-born porous zirconium hydroxide nanopowders with the help of X-ray diffraction (XRD), Brunauer–Emmett–Teller (BET) isotherm and Transmission Electron Microscopy (TEM) images are the main theme of this research work. Without any surfactants or <span class="hlt">pore</span> forming agents, the borohydride derived amorphous nature of porous powders was stable up to 500 °C and then the seed crystals start to develop within the loose amorphous matrix and trapping the inter-particulate voids, which led to develop the porous nature of tetragonal zirconium oxide at 600 °C and further sustain this porous nature as well as tetragonal phase of zirconium oxide up to 800 °C. The novel hydrogen (H2) gas-bubbles assisted borohydride synthesis route led to develop thermally stable porous zirconium hydroxide/oxide nanopowders with an adequate <span class="hlt">pore</span> size, <span class="hlt">pore</span> volume, and surface area and thus these porous materials are further suggested for promising use in different areas of applications. PMID:27198738</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/24416759','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/24416759"><span>Impedance nanopore biosensor: influence of <span class="hlt">pore</span> dimensions on biosensing performance.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Kant, Krishna; Yu, Jingxian; Priest, Craig; Shapter, Joe G; Losic, Dusan</p> <p>2014-03-07</p> <p>Knowledge about electrochemical and electrical properties of nanopore structures and the influence of <span class="hlt">pore</span> dimensions on these properties is important for the development of nanopore biosensing devices. The aim of this study was to explore the influence of nanopore dimensions (diameter and length) on biosensing performance using non-faradic electrochemical impedance spectroscopy (EIS). Nanoporous alumina membranes (NPAMs) prepared by self-ordered electrochemical anodization of aluminium were used as model nanopore sensing platforms. NPAMs with different <span class="hlt">pore</span> diameters (25-65 nm) and lengths (4-18 μm) were prepared and the internal <span class="hlt">pore</span> surface chemistry was modified by covalently attaching streptavidin and biotin. The performance of this antibody nanopore biosensing platform was evaluated using various concentrations of biotin as a model analyte. EIS measurements of <span class="hlt">pore</span> resistivity and conductivity were carried out for <span class="hlt">pores</span> with different diameters and lengths. The results showed that smaller <span class="hlt">pore</span> dimensions of 25 nm and <span class="hlt">pore</span> lengths up to 10 μm provide better biosensing performance.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/27265169','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/27265169"><span>Optimization of protein fractionation by skim milk microfiltration: Choice of ceramic membrane <span class="hlt">pore</span> size and filtration temperature.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Jørgensen, Camilla Elise; Abrahamsen, Roger K; Rukke, Elling-Olav; Johansen, Anne-Grethe; Schüller, Reidar B; Skeie, Siv B</p> <p>2016-08-01</p> <p>The objective of this study was to investigate how ceramic membrane <span class="hlt">pore</span> size and filtration temperature influence the protein fractionation of skim milk by cross flow microfiltration (MF). Microfiltration was performed at a uniform transmembrane <span class="hlt">pressure</span> with constant permeate flux to a volume concentration factor of 2.5. Three different membrane <span class="hlt">pore</span> sizes, 0.05, 0.10, and 0.20µm, were used at a filtration temperature of 50°C. Furthermore, at <span class="hlt">pore</span> size 0.10µm, 2 different filtration temperatures were investigated: 50 and 60°C. The transmission of proteins increased with increasing <span class="hlt">pore</span> size, giving the permeate from MF with the 0.20-µm membrane a significantly higher concentration of native whey proteins compared with the permeates from the 0.05- and 0.10-µm membranes (0.50, 0.24, and 0.39%, respectively). Significant amounts of caseins permeated the 0.20-µm membrane (1.4%), giving a permeate with a whitish appearance and a casein distribution (αS2-CN: αS1-CN: κ-CN: β-CN) similar to that of skim milk. The 0.05- and 0.10-µm membranes were able to retain all caseins (only negligible amounts were detected). A permeate free from casein is beneficial in the production of native whey protein concentrates and in applications where transparency is an important functional characteristic. Microfiltration of skim milk at 50°C with the 0.10-µm membrane resulted in a permeate containing significantly more native whey proteins than the permeate from MF at 60°C. The more rapid increase in transmembrane <span class="hlt">pressure</span> and the significantly lower concentration of caseins in the retentate at 60°C indicated that a higher concentration of caseins deposited on the membrane, and consequently reduced the native whey protein transmission. Optimal protein fractionation of skim milk into a casein-rich retentate and a permeate with native whey proteins were obtained by 0.10-µm MF at 50°C. Copyright © 2016 American Dairy Science Association. Published by Elsevier Inc. All</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/16219318','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/16219318"><span>Experimental and modeling study of Newtonian and non-Newtonian fluid flow in <span class="hlt">pore</span> network micromodels.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Perrin, Christian L; Tardy, Philippe M J; Sorbie, Ken S; Crawshaw, John C</p> <p>2006-03-15</p> <p>The in situ rheology of polymeric solutions has been studied experimentally in etched silicon micromodels which are idealizations of porous media. The rectangular channels in these etched networks have dimensions typical of <span class="hlt">pore</span> sizes in sandstone rocks. <span class="hlt">Pressure</span> drop/flow rate relations have been measured for water and non-Newtonian hydrolyzed-polyacrylamide (HPAM) solutions in both individual straight rectangular capillaries and in networks of such capillaries. Results from these experiments have been analyzed using <span class="hlt">pore</span>-scale network modeling incorporating the non-Newtonian fluid mechanics of a Carreau fluid. Quantitative agreement is seen between the experiments and the network calculations in the Newtonian and shear-thinning flow regions demonstrating that the 'shift factor,'alpha, can be calculated a priori. Shear-thickening behavior was observed at higher flow rates in the micromodel experiments as a result of elastic effects becoming important and this remains to be incorporated in the network model.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/servlets/purl/875105','DOE-PATENT-XML'); return false;" href="https://www.osti.gov/servlets/purl/875105"><span>Flowmeter for <span class="hlt">pressure</span>-driven chromatography systems</span></a></p> <p><a target="_blank" href="http://www.osti.gov/doepatents">DOEpatents</a></p> <p>Paul, Phillip H.; Arnold, Don W.</p> <p>2003-01-01</p> <p>A flowmeter for accurately measuring the flowrate of fluids in high <span class="hlt">pressure</span> chromatography systems. The flowmeter is a porous bed of a material, the porous bed having a porosity in the range of about 0.1 to 0.6 and a <span class="hlt">pore</span> size in the range of about 50 nm to 1 .mu.m, disposed between a high <span class="hlt">pressure</span> pumping means and a chromatography column. The flowmeter is provided with <span class="hlt">pressure</span> measuring means at both the inlet and outlet of the porous bed for measuring the <span class="hlt">pressure</span> drop through the porous bed. This flowmeter system provides not only the ability to measure accurately flowrates in the range of .mu.L/min to nL/min but also to provide a signal that can be used for a servo loop or feedback control system for high <span class="hlt">pressure</span> pumping systems.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li class="active"><span>24</span></li> <li><a href="#" onclick='return showDiv("page_25");'>25</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_24 --> <div id="page_25" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li><a href="#" onclick='return showDiv("page_24");'>24</a></li> <li class="active"><span>25</span></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="481"> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/servlets/purl/874788','DOE-PATENT-XML'); return false;" href="https://www.osti.gov/servlets/purl/874788"><span>Flowmeter for <span class="hlt">pressure</span>-driven chromatography systems</span></a></p> <p><a target="_blank" href="http://www.osti.gov/doepatents">DOEpatents</a></p> <p>Paul, Phillip H.; Arnold, Don W.</p> <p>2002-01-01</p> <p>A flowmeter for accurately measuring the flowrate of fluids in high <span class="hlt">pressure</span> chromatography systems. The flowmeter is a porous bed of a material, the porous bed having a porosity in the range of about 0.1 to 0.6 and a <span class="hlt">pore</span> size in the range of about 50 nm to 1 .mu.m, disposed between a high <span class="hlt">pressure</span> pumping means and a chromatography column. The flowmeter is provided with <span class="hlt">pressure</span> measuring means at both the inlet and outlet of the porous bed for measuring the <span class="hlt">pressure</span> drop through the porous bed. This flowmeter system provides not only the ability to measure accurately flowrates in the range of .mu.L/min to nL/min but also to provide a signal that can be used for a servo loop or feedback control system for high <span class="hlt">pressure</span> pumping systems.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/20466725','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/20466725"><span>Probing <span class="hlt">pore</span> constriction in a ligand-gated ion channel by trapping a metal ion in the <span class="hlt">pore</span> upon agonist dissociation.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Pittel, Ilya; Witt-Kehati, Dvora; Degani-Katzav, Nurit; Paas, Yoav</p> <p>2010-08-20</p> <p>Eukaryotic pentameric ligand-gated ion channels (pLGICs) are receptors activated by neurotransmitters to rapidly transport ions across cell membranes, down their electrochemical gradients. Recent crystal structures of two prokaryotic pLGICs were interpreted to imply that the extracellular side of the transmembrane <span class="hlt">pore</span> constricts to close the channel (Hilf, R. J., and Dutzler, R. (2009) Nature 457, 115-118; Bocquet, N., Nury, H., Baaden, M., Le Poupon, C., Changeux, J. P., Delarue, M., and Corringer, P. J. (2009) Nature 457, 111-114). Here, we utilized a eukaryotic acetylcholine (ACh)-serotonin chimeric pLGIC that was engineered with histidines to coordinate a metal ion within the channel <span class="hlt">pore</span>, at its cytoplasmic side. In a previous study, the access of Zn(2+) ions to the engineered histidines had been explored when the channel was either at rest (closed) or active (open) (Paas, Y., Gibor, G., Grailhe, R., Savatier-Duclert, N., Dufresne, V., Sunesen, M., de Carvalho, L. P., Changeux, J. P., and Attali, B. (2005) Proc. Natl. Acad. Sci. U.S.A. 102, 15877-15882). In this study, the interactions of Zn(2+) with the <span class="hlt">pore</span> were probed upon agonist (ACh) dissociation that triggers the transition of the receptor from the active conformation to the resting conformation (i.e. during deactivation). Application of Zn(2+) onto ACh-bound open receptors obstructed their <span class="hlt">pore</span> and prevented ionic flow. Removing ACh from its extracellular binding sites to trigger deactivation while Zn(2+) is still bound led to tight trapping of Zn(2+) within the <span class="hlt">pore</span>. Together with single-channel recordings, made to explore single <span class="hlt">pore</span>-blocking events, we show that dissociation of ACh causes the gate to shut on a Zn(2+) ion that effectively acts as a "foot in the door." We infer that, upon deactivation, the cytoplasmic side of the <span class="hlt">pore</span> of the ACh-serotonin receptor chimera constricts to close the channel.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5923567','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5923567"><span>Electrochemically-Driven Insertion of Biological Nanodiscs into Solid State Membrane <span class="hlt">Pores</span> as a Basis for “<span class="hlt">Pore</span>-In-Pore” Membranes</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Farajollahi, Farid; Seidenstücker, Axel; Altintoprak, Klara; Walther, Paul; Ziemann, Paul; Plettl, Alfred; Wege, Christina; Gliemann, Hartmut</p> <p>2018-01-01</p> <p>Nanoporous membranes are of increasing interest for many applications, such as molecular filters, biosensors, nanofluidic logic and energy conversion devices. To meet high-quality standards, e.g., in molecular separation processes, membranes with well-defined <span class="hlt">pores</span> in terms of <span class="hlt">pore</span> diameter and chemical properties are required. However, the preparation of membranes with narrow <span class="hlt">pore</span> diameter distributions is still challenging. In the work presented here, we demonstrate a strategy, a “<span class="hlt">pore</span>-in-pore” approach, where the conical <span class="hlt">pores</span> of a solid state membrane produced by a multi-step top-down lithography procedure are used as a template to insert precisely-formed biomolecular nanodiscs with exactly defined inner and outer diameters. These nanodiscs, which are the building blocks of tobacco mosaic virus-deduced particles, consist of coat proteins, which self-assemble under defined experimental conditions with a stabilizing short RNA. We demonstrate that the insertion of the nanodiscs can be driven either by diffusion due to a concentration gradient or by applying an electric field along the cross-section of the solid state membrane. It is found that the electrophoresis-driven insertion is significantly more effective than the insertion via the concentration gradient. PMID:29652841</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4337418','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4337418"><span>Facial skin <span class="hlt">pores</span>: a multiethnic study</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Flament, Frederic; Francois, Ghislain; Qiu, Huixia; Ye, Chengda; Hanaya, Tomoo; Batisse, Dominique; Cointereau-Chardon, Suzy; Seixas, Mirela Donato Gianeti; Dal Belo, Susi Elaine; Bazin, Roland</p> <p>2015-01-01</p> <p>Skin <span class="hlt">pores</span> (SP), as they are called by laymen, are common and benign features mostly located on the face (nose, cheeks, etc) that generate many aesthetic concerns or complaints. Despite the prevalence of skin <span class="hlt">pores</span>, related literature is scarce. With the aim of describing the prevalence of skin <span class="hlt">pores</span> and anatomic features among ethnic groups, a dermatoscopic instrument, using polarized lighting, coupled to a digital camera recorded the major features of skin <span class="hlt">pores</span> (size, density, coverage) on the cheeks of 2,585 women in different countries and continents. A detection threshold of 250 μm, correlated to clinical scorings by experts, was input into a specific software to further allow for automatic counting of the SP density (N/cm2) and determination of their respective sizes in mm2. Integrating both criteria also led to establishing the relative part of the skin surface (as a percentage) that is actually covered by SP on cheeks. The results showed that the values of respective sizes, densities, and skin coverage: 1) were recorded in all studied subjects; 2) varied greatly with ethnicity; 3) plateaued with age in most cases; and 4) globally refected self-assessment by subjects, in particular those who self-declare having “enlarged pores” like Brazilian women. Inversely, Chinese women were clearly distinct from other ethnicities in having very low density and sizes. Analyzing the present results suggests that facial skin pore’s morphology as perceived by human eye less result from functional criteria of associated appendages such as sebaceous glands. To what extent skin <span class="hlt">pores</span> may be viewed as additional criteria of a photo-altered skin is an issue to be further addressed. PMID:25733918</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5745516','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5745516"><span>Accurate Characterization of the <span class="hlt">Pore</span> Volume in Microporous Crystalline Materials</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p></p> <p>2017-01-01</p> <p><span class="hlt">Pore</span> volume is one of the main properties for the characterization of microporous crystals. It is experimentally measurable, and it can also be obtained from the refined unit cell by a number of computational techniques. In this work, we assess the accuracy and the discrepancies between the different computational methods which are commonly used for this purpose, i.e, geometric, helium, and probe center <span class="hlt">pore</span> volumes, by studying a database of more than 5000 frameworks. We developed a new technique to fully characterize the internal void of a microporous material and to compute the probe-accessible and -occupiable <span class="hlt">pore</span> volume. We show that, unlike the other definitions of <span class="hlt">pore</span> volume, the occupiable <span class="hlt">pore</span> volume can be directly related to the experimentally measured <span class="hlt">pore</span> volumes from nitrogen isotherms. PMID:28636815</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/pages/biblio/1368597-accurate-characterization-pore-volume-microporous-crystalline-materials','SCIGOV-DOEP'); return false;" href="https://www.osti.gov/pages/biblio/1368597-accurate-characterization-pore-volume-microporous-crystalline-materials"><span>Accurate Characterization of the <span class="hlt">Pore</span> Volume in Microporous Crystalline Materials</span></a></p> <p><a target="_blank" href="http://www.osti.gov/pages">DOE PAGES</a></p> <p>Ongari, Daniele; Boyd, Peter G.; Barthel, Senja; ...</p> <p>2017-06-21</p> <p><span class="hlt">Pore</span> volume is one of the main properties for the characterization of microporous crystals. It is experimentally measurable, and it can also be obtained from the refined unit cell by a number of computational techniques. In this work, we assess the accuracy and the discrepancies between the different computational methods which are commonly used for this purpose, i.e, geometric, helium, and probe center <span class="hlt">pore</span> volumes, by studying a database of more than 5000 frameworks. We developed a new technique to fully characterize the internal void of a microporous material and to compute the probe-accessible and -occupiable <span class="hlt">pore</span> volume. Lasty, wemore » show that, unlike the other definitions of <span class="hlt">pore</span> volume, the occupiable <span class="hlt">pore</span> volume can be directly related to the experimentally measured <span class="hlt">pore</span> volumes from nitrogen isotherms.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012AIPC.1430.1064C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012AIPC.1430.1064C"><span>Nondestructive assessment of <span class="hlt">pore</span> size in foam-based hybrid composite materials</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Chen, M. Y.; Ko, R. T.</p> <p>2012-05-01</p> <p>In-situ non-destructive evaluation (NDE) during processing of high temperature polymer based hybrids offers great potential to gain close control and achieve the desired level of <span class="hlt">pore</span> size, with low overall development cost. During the polymer curing cycle, close control over the evolution of volatiles would be beneficial to avoid the presence of <span class="hlt">pores</span> or at least control their sizes. Traditional NDE methods cannot realistically be expected to evaluate individual <span class="hlt">pores</span> in such components, as each <span class="hlt">pore</span> evolves and grows during curing. However, NDE techniques offer the potential to detect and quantify the macroscopic response of many <span class="hlt">pores</span> that are undesirable or intentionally introduced into these advanced materials. In this paper, preliminary results will be presented for nondestructive assessment of <span class="hlt">pore</span> size in foam-based hybrid composite materials using ultrasonic techniques. <span class="hlt">Pore</span> size was evaluated through the frequency content of the ultrasonic signal. The effects of <span class="hlt">pore</span> size on the attenuation of ultrasound were studied. Feasibility of this method was demonstrated on two types of foams with various <span class="hlt">pore</span> sizes.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013EGUGA..15.7453S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013EGUGA..15.7453S"><span>Geothermal alteration of Kamchatka rock physical properties: experimental and <span class="hlt">pore</span>-scale modeling study</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Shanina, Violetta; Gerke, Kirill; Bichkov, Andrey; Korost, Dmitry</p> <p>2013-04-01</p> <p> X-ray microtomography prior to any alteration and after the experiments. 3D images were used to quantify structural changes and to determine permeability values using a <span class="hlt">pore</span>-scale modeling approach, as laboratory measurements with through flow are known to have a potential to modify the <span class="hlt">pore</span> structure. Chemical composition and local mineral formations were investigated using a «Spectroscan Max GV» spectrometer and scanning electron microscope imaging. Our study revealed significant relationships between structure modifications, physical properties and alteration conditions. Main results and conclusions include: 1) initial porosity and its connectivity have substantial effect on alteration dynamics, rocks with higher porosity values and connected <span class="hlt">pore</span> space exhibit more pronounced alterations; 2) under similar experimental conditions (<span class="hlt">pressure</span>, temperature, duration) pH plays an important role, acidic conditions result in significant new mineral formation; 3) almost all physical properties, including porosity, permeability, and elastic properties, were seriously modified in the modeled geothermal processes within short (from geological point of view) time frames; 4) X-ray microtomography was found useful for mineral phases distribution and the <span class="hlt">pore</span>-scale modeling approach was found to be a promising technique to numerically obtain rock properties based on 3D scans; 5) we conclude that alteration and change of reservoir rocks should be taken into account for re-injecting well and geothermal power-plant design.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015APS..MARJ33012R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015APS..MARJ33012R"><span><span class="hlt">Pore</span> opening dynamics in the exocytosis of serotonin</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ramirez-Santiago, Guillermo; Cercos, Montserrat G.; Martinez-Valencia, Alejandro; Salinas Hernandez, Israel; Rodríguez-Sosa, Leonardo; de-Miguel, Francisco F.</p> <p>2015-03-01</p> <p>The current view of the exocytosis of transmitter molecules is that it starts with the formation of a fusion <span class="hlt">pore</span> that connects the intravesicular and the extracellular spaces, and is completed by the release of the rest of the transmitter contained in the vesicle upon the full fusion and collapse of the vesicle with the plasma membrane. However, under certain circumstances, a rapid closure of the <span class="hlt">pore</span> before the full vesicle fusion produces only a partial release of the transmitter. Here we show that whole release of the transmitter occurs through fusion <span class="hlt">pores</span> that remain opened for tens of milliseconds without vesicle collapse. This was demonstrated through amperometric measurements of serotonin release from electrodense vesicles in the axon of leech Retzius neurons and mathematical modelling. By modeling transmitter release with a diffusion equation subjected to boundary conditions that are defined by the experiment, we showed that those <span class="hlt">pores</span> with a fast half rise time constant remained opened and allowed the full quantum release without vesicle collapse, whereas <span class="hlt">pores</span> with a slow rise time constant closed rapidly, thus producing partial release. We conclude that a full transmitter release may occur through the fusion <span class="hlt">pore</span> in the absence of vesicle collapse. This work was founded by a DGAPA-UNAM grants IN200914 and IN118410 CONACYT GRANT 130031, and CONACyT doctoral fellowships.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/25418307','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/25418307"><span>Smooth DNA transport through a narrowed <span class="hlt">pore</span> geometry.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Carson, Spencer; Wilson, James; Aksimentiev, Aleksei; Wanunu, Meni</p> <p>2014-11-18</p> <p>Voltage-driven transport of double-stranded DNA through nanoscale <span class="hlt">pores</span> holds much potential for applications in quantitative molecular biology and biotechnology, yet the microscopic details of translocation have proven to be challenging to decipher. Earlier experiments showed strong dependence of transport kinetics on <span class="hlt">pore</span> size: fast regular transport in large <span class="hlt">pores</span> (> 5 nm diameter), and slower yet heterogeneous transport time distributions in sub-5 nm <span class="hlt">pores</span>, which imply a large positional uncertainty of the DNA in the <span class="hlt">pore</span> as a function of the translocation time. In this work, we show that this anomalous transport is a result of DNA self-interaction, a phenomenon that is strictly <span class="hlt">pore</span>-diameter dependent. We identify a regime in which DNA transport is regular, producing narrow and well-behaved dwell-time distributions that fit a simple drift-diffusion theory. Furthermore, a systematic study of the dependence of dwell time on DNA length reveals a single power-law scaling of 1.37 in the range of 35-20,000 bp. We highlight the resolution of our nanopore device by discriminating via single pulses 100 and 500 bp fragments in a mixture with >98% accuracy. When coupled to an appropriate sequence labeling method, our observation of smooth DNA translocation can pave the way for high-resolution DNA mapping and sizing applications in genomics.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4241440','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4241440"><span>Smooth DNA Transport through a Narrowed <span class="hlt">Pore</span> Geometry</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Carson, Spencer; Wilson, James; Aksimentiev, Aleksei; Wanunu, Meni</p> <p>2014-01-01</p> <p>Voltage-driven transport of double-stranded DNA through nanoscale <span class="hlt">pores</span> holds much potential for applications in quantitative molecular biology and biotechnology, yet the microscopic details of translocation have proven to be challenging to decipher. Earlier experiments showed strong dependence of transport kinetics on <span class="hlt">pore</span> size: fast regular transport in large <span class="hlt">pores</span> (> 5 nm diameter), and slower yet heterogeneous transport time distributions in sub-5 nm <span class="hlt">pores</span>, which imply a large positional uncertainty of the DNA in the <span class="hlt">pore</span> as a function of the translocation time. In this work, we show that this anomalous transport is a result of DNA self-interaction, a phenomenon that is strictly <span class="hlt">pore</span>-diameter dependent. We identify a regime in which DNA transport is regular, producing narrow and well-behaved dwell-time distributions that fit a simple drift-diffusion theory. Furthermore, a systematic study of the dependence of dwell time on DNA length reveals a single power-law scaling of 1.37 in the range of 35–20,000 bp. We highlight the resolution of our nanopore device by discriminating via single pulses 100 and 500 bp fragments in a mixture with >98% accuracy. When coupled to an appropriate sequence labeling method, our observation of smooth DNA translocation can pave the way for high-resolution DNA mapping and sizing applications in genomics. PMID:25418307</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016JNuM..478..275K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016JNuM..478..275K"><span><span class="hlt">Pore</span> growth in U-Mo/Al dispersion fuel</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kim, Yeon Soo; Jeong, G. Y.; Sohn, D.-S.; Jamison, L. M.</p> <p>2016-09-01</p> <p>U-Mo/Al dispersion fuel is currently under development in the DOE's Material Management and Minimization program to convert HEU-fueled research reactors to LEU-fueled reactors. In some demanding conditions in high-power and high-performance reactors, large <span class="hlt">pores</span> form in the interaction layers between the U-Mo fuel particles and the Al matrix, which pose a potential to cause fuel failure. In this study, comprehension of the formation and growth of these <span class="hlt">pores</span> was explored. As a product, a model to predict <span class="hlt">pore</span> growth and porosity increase was developed. The model includes three major topics: fission gas release from the U-Mo and the IL to the <span class="hlt">pores</span>, stress evolution in the fuel meat, and the effect of amorphous IL growth. Well-characterized in-pile data from reduced-size plates were used to fit the model parameters. A data set from full-sized plates, independent and distinctively different from those used to fit the model parameters, was used to examine the accuracy of the model. The model showed fair agreement with the measured data. The model suggested that the growth of the IL has a critical effect on <span class="hlt">pore</span> growth, as both its material properties and energetics are favorable to <span class="hlt">pore</span> formation. Therefore, one area of the current effort, focused on suppressing IL growth, appears to be on the right track to improve the performance of this fuel.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017EGUGA..1916395L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017EGUGA..1916395L"><span>Three-Dimensional Quantification of <span class="hlt">Pore</span> Space in Flocculated Sediments</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Lawrence, Tom; Spencer, Kate; Bushby, Andy; Manning, Andrew</p> <p>2017-04-01</p> <p>Flocculated sediment structure plays a vital role in determining sediment dynamics within the water column in fresh and saline water bodies. The porosity of flocs contributes to their specific density and therefore their settling characteristics, and can also affect settling characteristics via through-flow. The process of settling and resuspension of flocculated material causes the formation of larger and more complex individual flocs, about which little is known quantitatively of the internal micro-structure and therefore porosity. Hydrological and sedimentological modelling software currently uses estimations of porosity, because it is difficult to capture and analyse flocs. To combat this, we use a novel microscopy method usually performed on biological material to scan the flocs, the output of which can be used to quantify the dimensions and arrangement of <span class="hlt">pores</span>. This involves capturing flocculated sediment, staining the sample with heavy metal elements to highlight organic content in the Scanning Electron Microscope later, and finally setting the sample in resin. The overall research aim is to quantitatively characterise the dimensions and distribution of <span class="hlt">pore</span> space in flocs in three dimensions. In order to gather data, Scanning Electron Microscopy and micro-Computed Tomography have been utilised to produce the necessary images to identify and quantify the <span class="hlt">pore</span> space. The first objective is to determine the dimensional limits of <span class="hlt">pores</span> in the structure (i.e. what area do they encapsulate? Are they interconnected or discreet?). This requires a repeatable definition to be established, so that all floc <span class="hlt">pore</span> spaces can be quantified using the same parameters. The LabSFLOC settling column and dyes will be used as one possible method of determining the outer limits of the discreet <span class="hlt">pore</span> space. LabSFLOC is a sediment settling column that uses a camera to record the flocs, enabling analysis of settling characteristics. The second objective is to develop a reliable</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://eric.ed.gov/?q=abnormal+AND+psychology&pg=6&id=EJ218605','ERIC'); return false;" href="https://eric.ed.gov/?q=abnormal+AND+psychology&pg=6&id=EJ218605"><span>Feeling <span class="hlt">Abnormal</span>: Simulation of Deviancy in <span class="hlt">Abnormal</span> and Exceptionality Courses.</span></a></p> <p><a target="_blank" href="http://www.eric.ed.gov/ERICWebPortal/search/extended.jsp?_pageLabel=advanced">ERIC Educational Resources Information Center</a></p> <p>Fernald, Charles D.</p> <p>1980-01-01</p> <p>Describes activity in which student in <span class="hlt">abnormal</span> psychology and psychology of exceptional children classes personally experience being judged <span class="hlt">abnormal</span>. The experience allows the students to remember relevant research, become sensitized to the feelings of individuals classified as deviant, and use caution in classifying individuals as <span class="hlt">abnormal</span>.…</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/19689751','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/19689751"><span><span class="hlt">Abnormal</span> blood <span class="hlt">pressure</span> circadian rhythm in acute ischaemic stroke: are lacunar strokes really different?</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Castilla-Guerra, L; Espino-Montoro, A; Fernández-Moreno, M C; López-Chozas, J M</p> <p>2009-08-01</p> <p>A pathologically reduced or abolished circadian blood <span class="hlt">pressure</span> variation has been described in acute stroke. However, studies on alterations of circadian blood <span class="hlt">pressure</span> patterns after stroke and stroke subtypes are scarce. The objective of this study was to evaluate the changes in circadian blood <span class="hlt">pressure</span> patterns in patients with acute ischaemic stroke and their relation to the stroke subtype. We studied 98 consecutive patients who were admitted within 24 h after ischaemic stroke onset. All patients had a detailed clinical examination, laboratory studies and a CT scan study of the brain on admission. To study the circadian rhythm of blood <span class="hlt">pressure</span>, a continuous blood <span class="hlt">pressure</span> monitor (Spacelab 90217) was used. Patients were classified according to the percentage fall in the mean systolic blood <span class="hlt">pressure</span> or diastolic blood <span class="hlt">pressure</span> at night compared with during the day as: dippers (fall> or =10-20%); extreme dippers (> or =20%); nondipper (<10%); and reverse dippers (<0%, that is, an increase in the mean nocturnal blood <span class="hlt">pressure</span> compared with the mean daytime blood <span class="hlt">pressure</span>). Data were separated and analysed in two groups: lacunar and nonlacunar infarctions. Statistical testing was conducted using the SSPS 12.0. Methods We studied 60 males and 38 females, mean age: 70.5+/-11 years. The patient population consisted of 62 (63.2%) lacunar strokes and 36 (36.8%) nonlacunar strokes. Hypertension was the most common risk factor (67 patients, 68.3%). Other risk factors included hypercholesterolaemia (44 patients, 44.8%), diabetes mellitus (38 patients, 38.7%), smoking (24 patients, 24.8%) and atrial fibrillation (19 patients, 19.3%). The patients with lacunar strokes were predominantly men (P=0.037) and had a lower frequency of atrial fibrillation (P=0.016) as compared with nonlacunar stroke patients. In the acute phase, the mean systolic blood <span class="hlt">pressure</span> was 136+/-20 mmHg and diastolic blood <span class="hlt">pressure</span> was 78.7+/-11.8. Comparing stroke subtypes, there were no differences in</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://familydoctor.org/condition/abnormal-uterine-bleeding/?adfree=true','NIH-MEDLINEPLUS'); return false;" href="https://familydoctor.org/condition/abnormal-uterine-bleeding/?adfree=true"><span><span class="hlt">Abnormal</span> Uterine Bleeding</span></a></p> <p><a target="_blank" href="http://medlineplus.gov/">MedlinePlus</a></p> <p></p> <p></p> <p>... <span class="hlt">abnormal</span> uterine bleeding? <span class="hlt">Abnormal</span> uterine bleeding is any heavy or unusual bleeding from the uterus (through your ... one symptom of <span class="hlt">abnormal</span> uterine bleeding. Having extremely heavy bleeding during your period can also be considered ...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1999WRR....35.1089F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1999WRR....35.1089F"><span>Prediction of relative and absolute permeabilities for gas and water from soil water retention curves using a <span class="hlt">pore</span>-scale network model</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Fischer, Ulrich; Celia, Michael A.</p> <p>1999-04-01</p> <p>Functional relationships for unsaturated flow in soils, including those between capillary <span class="hlt">pressure</span>, saturation, and relative permeabilities, are often described using analytical models based on the bundle-of-tubes concept. These models are often limited by, for example, inherent difficulties in prediction of absolute permeabilities, and in incorporation of a discontinuous nonwetting phase. To overcome these difficulties, an alternative approach may be formulated using <span class="hlt">pore</span>-scale network models. In this approach, the <span class="hlt">pore</span> space of the network model is adjusted to match retention data, and absolute and relative permeabilities are then calculated. A new approach that allows more general assignments of <span class="hlt">pore</span> sizes within the network model provides for greater flexibility to match measured data. This additional flexibility is especially important for simultaneous modeling of main imbibition and drainage branches. Through comparisons between the network model results, analytical model results, and measured data for a variety of both undisturbed and repacked soils, the network model is seen to match capillary <span class="hlt">pressure</span>-saturation data nearly as well as the analytical model, to predict water phase relative permeabilities equally well, and to predict gas phase relative permeabilities significantly better than the analytical model. The network model also provides very good estimates for intrinsic permeability and thus for absolute permeabilities. Both the network model and the analytical model lost accuracy in predicting relative water permeabilities for soils characterized by a van Genuchten exponent n≲3. Overall, the computational results indicate that reliable predictions of both relative and absolute permeabilities are obtained with the network model when the model matches the capillary <span class="hlt">pressure</span>-saturation data well. The results also indicate that measured imbibition data are crucial to good predictions of the complete hysteresis loop.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/18939572','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/18939572"><span>Measuring temporal variability in <span class="hlt">pore</span>-fluid chemistry to assess gas hydrate stability: development of a continuous <span class="hlt">pore</span>-fluid array.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Lapham, Laura L; Chanton, Jeffrey P; Martens, Christopher S; Higley, Paul D; Jannasch, Hans W; Woolsey, J Robert</p> <p>2008-10-01</p> <p>A specialized <span class="hlt">pore</span>-fluid array (PFA) sampler was designed to collect and store <span class="hlt">pore</span> fluids to monitor temporal changes of ions and gases in gas hydrate bearing sediments. We tested the hypothesis that <span class="hlt">pore</span>-fluid chemistry records hydrate formation or decomposition events and reflects local seismic activity. The PFA is a seafloor probe that consists of an interchangeable instrument package that houses OsmoSamplers, long-term <span class="hlt">pore</span>-fluid samplers, a specialized low-dead volume fluid coupler, and eight sample ports along a 10 m sediment probe shaft. The PFA was deployed at Mississippi Canyon 118, a Gulf of Mexico hydrate site. A 170 day record was acquired from the overlying water and 1.3 m below seafloor (mbsf). Fluids were measured for dissolved chloride, sulfate, and methane concentrations and dissolved inorganic carbon and methane stable carbon and deuterium isotope ratios. Chloride and sulfate did not change significantly over time, suggesting the absence of gas hydrate formation or decomposition events. Over the temporal record, methane concentrations averaged 4 mM at 1.3 mbsf, and methane was thermogenic in origin (delta13C-CH4 = -32.4 +/- 3.4 per thousand). The timing of an anomalous 14 mM methane spike coincided with a nearby earthquake (Mw = 5.8), consistent with the hypothesis that <span class="hlt">pore</span>-fluid chemistry reflects seismic events.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2008AGUFMNS43B1193G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2008AGUFMNS43B1193G"><span>Estimating <span class="hlt">Pore</span> Properties from NMR Relaxation Time Measurements in Heterogeneous Media</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Grunewald, E.; Knight, R.</p> <p>2008-12-01</p> <p>The link between <span class="hlt">pore</span> geometry and the nuclear magnetic resonance (NMR) relaxation time T2 is well- established for simple systems but is poorly understood for complex media with heterogeneous <span class="hlt">pores</span>. Conventional interpretation of NMR relaxation data employs a model of isolated <span class="hlt">pores</span> in which each hydrogen proton samples only one <span class="hlt">pore</span> type, and the T2-distribution is directly scaled to estimate a <span class="hlt">pore</span>-size distribution. During an actual NMR measurement, however, each proton diffuses through a finite volume of the <span class="hlt">pore</span> network, and so may sample multiple <span class="hlt">pore</span> types encountered within this diffusion cell. For cases in which heterogeneous <span class="hlt">pores</span> are strongly coupled by diffusion, the meaning of the T2- distribution is not well understood and further research is required to determine how such measurements should be interpreted. In this study we directly investigate the implications of <span class="hlt">pore</span> coupling in two groups of laboratory NMR experiments. We conduct two suites of experiments, in which samples are synthesized to exhibit a range of <span class="hlt">pore</span> coupling strengths using two independent approaches: (a) varying the scale of the diffusion cell and (b) varying the scale over which heterogeneous <span class="hlt">pores</span> are encountered. In the first set of experiments, we vary the scale of the diffusion cell in silica gels which have a bimodal <span class="hlt">pore</span>-size distribution comprised of intragrannular micropores and much larger intergrannular <span class="hlt">pores</span>. The untreated gel exhibits strong <span class="hlt">pore</span> coupling with a single broad peak observed in the T2-distribution. By treating the gel with varied amounts of paramagnetic iron surface coatings, we decrease the surface relaxation time, T2S, and effectively decrease both the size of the diffusion cell and the degree of <span class="hlt">pore</span> coupling. As more iron is coated to the grain surfaces, we observe a separation of the broad T2-distribution into two peaks that more accurately represent the true bimodal <span class="hlt">pore</span>-size distribution. In the second set of experiments, we vary the scale over</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/pages/biblio/1379705-pore-scale-supercritical-co2-dissolution-mass-transfer-under-drainage-conditions','SCIGOV-DOEP'); return false;" href="https://www.osti.gov/pages/biblio/1379705-pore-scale-supercritical-co2-dissolution-mass-transfer-under-drainage-conditions"><span><span class="hlt">Pore</span>-scale supercritical CO 2 dissolution and mass transfer under drainage conditions</span></a></p> <p><a target="_blank" href="http://www.osti.gov/pages">DOE PAGES</a></p> <p>Chang, Chun; Zhou, Quanlin; Oostrom, Mart; ...</p> <p>2016-12-05</p> <p>Recently, both core- and <span class="hlt">pore</span>-scale imbibition experiments have shown non-equilibrium dissolution of supercritical CO 2 (scCO 2) and a prolonged depletion of residual scCO 2. In this paper, <span class="hlt">pore</span>-scale scCO 2 dissolution and mass transfer under drainage conditions were investigated using a two-dimensional heterogeneous micromodel and a novel fluorescent water dye with a sensitive pH range between 3.7 and 6.5. Drainage experiments were conducted at 9 MPa and 40 °C by injecting scCO 2 into the sandstone-analogue <span class="hlt">pore</span> network initially saturated by water without dissolved CO 2 (dsCO 2). During the experiments, time-lapse images of dye intensity, reflecting water pH,more » were obtained. These images show non-uniform pH in individual <span class="hlt">pores</span> and <span class="hlt">pore</span> clusters, with average pH levels gradually decreasing with time. Further analysis on selected <span class="hlt">pores</span> and <span class="hlt">pore</span> clusters shows that (1) rate-limited mass transfer prevails with slowly decreasing pH over time when the scCO 2-water interface area is low with respect to the volume of water-filled <span class="hlt">pores</span> and <span class="hlt">pore</span> clusters, (2) fast scCO 2 dissolution and phase equilibrium occurs when scCO 2 bubbles invade into water-filled <span class="hlt">pores</span>, significantly enhancing the area-to-volume ratio, and (3) a transition from rate-limited to diffusion-limited mass transfer occurs in a single <span class="hlt">pore</span> when a medium area-to-volume ratio is prevalent. The analysis also shows that two fundamental processes – scCO 2 dissolution at phase interfaces and diffusion of dsCO 2 at the <span class="hlt">pore</span> scale (10–100 µm) observed after scCO 2 bubble invasion into water-filled <span class="hlt">pores</span> without <span class="hlt">pore</span> throat constraints – are relatively fast. The overall slow dissolution of scCO 2 in the millimeter-scale micromodel can be attributed to the small area-to-volume ratios that represent <span class="hlt">pore</span>-throat configurations and characteristics of phase interfaces. Finally, this finding is applicable for the behavior of dissolution at <span class="hlt">pore</span>, core, and field scales when water-filled <span class="hlt">pores</span> and <span class="hlt">pore</span></p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li><a href="#" onclick='return showDiv("page_24");'>24</a></li> <li class="active"><span>25</span></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_25 --> <div class="footer-extlink text-muted" style="margin-bottom:1rem; text-align:center;">Some links on this page may take you to non-federal websites. Their policies may differ from this site.</div> </div><!-- container --> <footer><a id="backToTop" href="#top"> </a><nav><a id="backToTop" href="#top"> </a><ul class="links"><a id="backToTop" href="#top"> </a><li><a id="backToTop" href="#top"></a><a href="/sitemap.html">Site Map</a></li> <li><a href="/members/index.html">Members Only</a></li> <li><a href="/website-policies.html">Website Policies</a></li> <li><a href="https://doe.responsibledisclosure.com/hc/en-us" target="_blank">Vulnerability Disclosure Program</a></li> <li><a href="/contact.html">Contact Us</a></li> </ul> <div class="small">Science.gov is maintained by the U.S. Department of Energy's <a href="https://www.osti.gov/" target="_blank">Office of Scientific and Technical Information</a>, in partnership with <a href="https://www.cendi.gov/" target="_blank">CENDI</a>.</div> </nav> </footer> <script type="text/javascript"><!-- // var lastDiv = ""; function showDiv(divName) { // hide last div if (lastDiv) { document.getElementById(lastDiv).className = "hiddenDiv"; } //if value of the box is not nothing and an object with that name exists, then change the class if (divName && document.getElementById(divName)) { document.getElementById(divName).className = "visibleDiv"; lastDiv = divName; } } //--> </script> <script> /** * Function that tracks a click on an outbound link in Google Analytics. * This function takes a valid URL string as an argument, and uses that URL string * as the event label. */ var trackOutboundLink = function(url,collectionCode) { try { h = window.open(url); setTimeout(function() { ga('send', 'event', 'topic-page-click-through', collectionCode, url); }, 1000); } catch(err){} }; </script> <!-- Google Analytics --> <script> (function(i,s,o,g,r,a,m){i['GoogleAnalyticsObject']=r;i[r]=i[r]||function(){ (i[r].q=i[r].q||[]).push(arguments)},i[r].l=1*new Date();a=s.createElement(o), m=s.getElementsByTagName(o)[0];a.async=1;a.src=g;m.parentNode.insertBefore(a,m) })(window,document,'script','//www.google-analytics.com/analytics.js','ga'); ga('create', 'UA-1122789-34', 'auto'); ga('send', 'pageview'); </script> <!-- End Google Analytics --> <script> showDiv('page_1') </script> </body> </html>