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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. 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

  3. 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.

  4. 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.

  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. 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).

  7. 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.

  8. 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.

  9. 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

  10. 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.

  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. 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.

  13. 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.

  14. 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.

  15. 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

  16. 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.

  17. 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.

  18. 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

  19. 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.

  20. Explicit Pore Pressure Material Model in Carbon-Cloth Phenolic

    NASA Technical Reports Server (NTRS)

    Gutierrez-Lemini, Danton; Ehle, Curt

    2003-01-01

    An explicit material model that uses predicted pressure in the pores 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

  1. 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,.

  2. Integrated landslide monitoring: rainfalls, pore water pressures and surface movements

    NASA Astrophysics Data System (ADS)

    Berti, M.; Casula, G.; Elmi, C.; Fabris, M.; Ghirotti, M.; Loddo, F.; Mora, P.; Pesci, A.; Simoni, A.

    2003-04-01

    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 pore-pressure 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 pore water pressure 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

  3. 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.

  4. 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.

  5. 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

  6. 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.

  7. 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.

  8. 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

  9. 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

  10. 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

  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. 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.

  13. 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.

  14. 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.

  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. Effects of Pore Distributions on Ductility of Thin-Walled High Pressure Die-Cast Magnesium

    SciTech Connect

    Choi, Kyoo Sil; Li, Dongsheng; Sun, Xin

    2013-06-01

    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 pressure 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 pore distribution features. The experimentally observed pore distribution features are then used to generate a series of synthetic microstructure-based 3D finite element models with different pore volume fractions and pore 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 pore volume fraction increases and that the effect of ‘skin region’ on the ductility is noticeable under the condition of same local pore 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 pore size and pore size distribution.« less

  17. 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.

  18. 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.

  19. Temporal pore pressure induced stress changes during injection and depletion

    NASA Astrophysics Data System (ADS)

    Müller, Birgit; Heidbach, Oliver; Schilling, Frank; Fuchs, Karl; Röckel, Thomas

    2016-04-01

    Induced seismicity is observed during injection of fluids in oil, gas or geothermal wells as a rather immediate response close to the injection wells due to the often high-rate pressurization. It was recognized even earlier in connection with more moderate rate injection of fluid waste on a longer time frame but higher induced event magnitudes. Today, injection-related induced seismicity significantly increased the number of events with M>3 in the Mid U.S. However, induced seismicity is also observed during production of fluids and gas, even years after the onset of production. E.g. in the Groningen gas field production was required to be reduced due to the increase in felt and damaging seismicity after more than 50 years of exploitation of that field. Thus, injection and production induced seismicity can cause severe impact in terms of hazard but also on economic measures. In order to understand the different onset times of induced seismicity we built a generic model to quantify the role of poro-elasticity processes with special emphasis on the factors time, regional crustal stress conditions and fault parameters for three case studies (injection into a low permeable crystalline rock, hydrothermal circulation and production of fluids). With this approach we consider the spatial and temporal variation of reservoir stress paths, the "early" injection-related induced events during stimulation and the "late" production induced ones. Furthermore, in dependence of the undisturbed in situ stress field conditions the stress tensor can change significantly due to injection and long-term production with changes of the tectonic stress regime in which previously not critically stressed faults could turn to be optimally oriented for fault reactivation.

  20. 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.

  1. Pore-water pressures associated with clogging of soil pipes: Numerical analysis of laboratory experiments

    USDA-ARS?s Scientific Manuscript database

    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 pore water pressures within pip...

  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. Variability of in situ sediment strength and pore pressure behavior of tidal estuary surface sediments

    NASA Astrophysics Data System (ADS)

    Lucking, Greg; Stark, Nina; Lippmann, Thomas; Smyth, Stephen

    2017-10-01

    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 pore pressure behavior with regard to sediment type and seabed morphology. The study also provides a detailed analysis of high velocity impact pore pressure 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 pore pressures approached equilibrium after penetration was classified and related to sediment type. The data indicate that the development of excess pore pressures 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 pore pressure behavior can vary significantly within a tidal estuary.

  4. 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

  5. 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

  6. 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.

  7. 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.

  8. 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

  9. Heterogeneity, pore pressure, and injectate chemistry: Control measures for geologic carbon storage

    SciTech Connect

    Dewers, Thomas; Eichhubl, Peter; Ganis, Ben

    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 pore pressure, 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 pressure 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 pore pressure 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 pore pressure hazards and enhance residual CO 2 trapping.« less

  10. Heterogeneity, pore pressure, and injectate chemistry: Control measures for geologic carbon storage

    DOE PAGES

    Dewers, Thomas; Eichhubl, Peter; Ganis, Ben; ...

    2017-11-28

    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 pore pressure, 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 pressure 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 pore pressure 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 pore pressure hazards and enhance residual CO 2 trapping.« less

  11. 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

  12. Assessment of pore pressures and specific storage within sedimentary strata overlying underground mines

    NASA Astrophysics Data System (ADS)

    Timms, W.; David, K.; Barbour, L. S.

    2016-12-01

    Realistic values of specific storage (Ss) for groundwater systems are important to determine the spatial extent and timing of c pore pressure 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 pore pressure data to evaluate variability and changes in Ss within sedimentary strata overlying a longwall coal mine. Pore pressure data from a vertical series of 6 vibrating wire piezometers (50 to 278 m depth) recording at hourly intervals were compared with barometric pressure 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 pore pressure 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

  13. 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.

  14. 14 CFR 91.144 - Temporary restriction on flight operations during abnormally high barometric pressure conditions.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... during abnormally high barometric pressure conditions. 91.144 Section 91.144 Aeronautics and Space... flight operations during abnormally high barometric pressure conditions. (a) Special flight restrictions. When any information indicates that barometric pressure on the route of flight currently exceeds or...

  15. 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.

  16. 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.

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

    SciTech Connect

    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

  18. Geomechanical modelling of induced seismicity using Coulomb stress and pore pressure changes

    NASA Astrophysics Data System (ADS)

    Zhao, B.; Shcherbakov, R.

    2016-12-01

    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 pore pressure 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 pore pressure 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 pore pressure 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.

  19. A pore-pressure diffusion model for estimating landslide-inducing rainfall

    USGS Publications Warehouse

    Reid, M.E.

    1994-01-01

    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 pressure diffusion model that provides a physically based hydrologic link between rainfall intensity/duration at the ground surface and destabilizing pore-water pressures 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

  20. 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

  1. Elucidating the mechanical effects of pore water pressure increase on the stability of unsaturated soil slopes

    NASA Astrophysics Data System (ADS)

    Buscarnera, G.

    2012-12-01

    The increase of the pore water pressure 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 pore water pressure, 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 pore 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 pore pressure increase can be understood as a trigger of uncontrolled strains, which at material point level are reflected by the onset of bifurcation conditions.

  2. Multiscale Pore Throat Network Reconstruction of Tight Porous Media Constrained by Mercury Intrusion Capillary Pressure and Nuclear Magnetic Resonance Measurements

    NASA Astrophysics Data System (ADS)

    Xu, R.; Prodanovic, M.

    2017-12-01

    Due to the low porosity and permeability of tight porous media, hydrocarbon productivity strongly depends on the pore structure. Effective characterization of pore/throat sizes and reconstruction of their connectivity in tight porous media remains challenging. Having a representative pore 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 pore-body and pore-throat size distributions. In this work, we combine mercury intrusion capillary pressure (MICP) and nuclear magnetic resonance (NMR) measurements by percolation theory to derive pore-body size distribution, following the work by Daigle et al. (2015). However, in their work, the actual pore-throat sizes and the distribution of coordination numbers are not well-defined. To compensate for that, we build a 3D unstructured two-scale pore throat network model initialized by the measured porosity and the calculated pore-body size distributions, with a tunable pore-throat size and coordination number distribution, which we further determine by matching the capillary pressure vs. saturation curve from MICP measurement, based on the fact that the mercury intrusion process is controlled by both the pore/throat size distributions and the connectivity of the pore 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 pore throat network we get can be used to further calculate relative permeability curves and simulate multiphase flow behavior, which will provide valuable

  3. Recharge and Transient Pore Pressure Propagation in Steep Alpine Mountain Slopes near Poschiavo, Switzerland

    NASA Astrophysics Data System (ADS)

    de Palézieux, Larissa; Loew, Simon; Zwahlen, Peter

    2017-04-01

    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 pressure packer tests were executed at various depths and pore water pressure 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 pressure records from these deep boreholes and relates them to seasonal recharge trends from snow melt and summer rainstorm events. Annual pore pressure 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 pressure function to the observed (delayed and attenuated) pore pressure records using a convolution of the one-dimensional pressure 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 pressure 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 pore pressure sensors are located only

  4. The effects of pressure, temperature, and pore water on velocities in Westerly granite. [for seismic wave propagation

    NASA Technical Reports Server (NTRS)

    Spencer, J. W., Jr.; Nur, A. M.

    1976-01-01

    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 pressures and with independent control of the pore pressure. The apparatus was used in studies of the joint effects of temperature, external confining pressure, and internal pore water on sonic velocities in Westerly granite. It was found that at a given temperature, confining pressure has a larger accelerating effect on compressional waves in dry rock, whereas at a given confining pressure, temperature has a larger retarding effect on shear waves.

  5. Effects of pore pressure and mud filtration on drilling rates in a permeable sandstone

    SciTech Connect

    Black, A.D.; DiBona, B.; Sandstrom, J.

    1983-10-01

    During laboratory drilling tests in a permeable sandstone, the effects of pore pressure 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 pressure with different back pressures 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

  6. Deformation of volcanic materials by pore pressurization: analog experiments with simplified geometry

    NASA Astrophysics Data System (ADS)

    Hyman, David; Bursik, Marcus

    2018-03-01

    The pressurization of pore 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 pressures. 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 pore pressure 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 pressurization wherein higher pressure ratios yielded larger deformations. For λ >10, fluid expulsion from the layer was much faster, vertically fracturing to the surface with larger pressure 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.

  7. Movement of Landslide Triggered by Bedrock Exfiltration with Nonuniform Pore Pressure Distribution

    NASA Astrophysics Data System (ADS)

    Jan, C. D.; Jian, Z. K.

    2014-12-01

    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 pore water pressure. 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 pore pressure 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 pressure 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.

  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. Hydromechanical Rock Mass Fatigue in Deep-Seated Landslides Accompanying Seasonal Variations in Pore Pressures

    NASA Astrophysics Data System (ADS)

    Preisig, Giona; Eberhardt, Erik; Smithyman, Megan; Preh, Alexander; Bonzanigo, Luca

    2016-06-01

    The episodic movement of deep-seated landslides is often governed by the presence of high pore pressures and reduced effective stresses along active shear surfaces. Pore pressures 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 pore pressure 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 pore pressure 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

  10. Dynamic Stability of the Rate, State, Temperature, and Pore Pressure Friction Model at a Rock Interface

    NASA Astrophysics Data System (ADS)

    Sinha, Nitish; Singh, Arun K.; Singh, Trilok N.

    2018-05-01

    In this article, we study numerically the dynamic stability of the rate, state, temperature, and pore pressure 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 pressurization including dilatancy and permeability of the pore 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 pressurization. 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 pressurization, 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 pressurization 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.

  11. Experimental Studies of Dynamic Fault Weakening Due to Thermal Pressurization of Pore Fluids

    NASA Astrophysics Data System (ADS)

    Goldsby, David; Tullis, Terry; Platt, John; Okazaki, Keishi

    2016-04-01

    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 pressurization is one possible coseismic weakening mechanism driven by the thermal expansion of native pore fluids, which leads to elevated pore pressures and significant coseismic weakening. While thermal pressurization 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 pressurization, 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 pressurization experiments on fluid-saturated, low-permeability rocks (Frederick diabase) at slip rates up to ~5 mm/s, at constant confining pressures in the range 21-149 MPa and initial imposed pore pressures 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 pore pressures 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

  12. 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

  13. Effects of pore pressure and mud filtration on drilling rates in a permeable sandstone

    SciTech Connect

    Black, A.D.; Dearing, H.L.; DiBona, B.G.

    1985-09-01

    During laboratory drilling tests in a permeable sandstone, the effects of pore pressure 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 pressure 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

  14. Tremor-tide correlations and near-lithostatic pore pressure on the deep San Andreas fault.

    PubMed

    Thomas, Amanda M; Nadeau, Robert M; Bürgmann, Roland

    2009-12-24

    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 pressurized pore 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 pore pressure. 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.

  15. Effect of Pore Pressure on Slip Failure of an Impermeable Fault: A Coupled Micro Hydro-Geomechanical Model

    NASA Astrophysics Data System (ADS)

    Yang, Z.; Juanes, R.

    2015-12-01

    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 pressure perturbation on the slip behavior of a sealing fault. The model couples single-phase flow in the pores 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 pore network is extracted for each granular pack with pore body volumes and pore throat conductivities calculated rigorously based on geometry of the local pore space. The pore fluid pressure 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 pore pressure. We proceed to study the fault stability in presence of a pressure discontinuity across the impermeable fault which is implemented as a plane with its intersected pore 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 pore fluid flow. The implication on how should faults be treated in a large-scale continuum model is also presented.

  16. Pore Structure and Limit Pressure of Gas Slippage Effect in Tight Sandstone

    PubMed Central

    You, Lijun; Xue, Kunlin; Kang, Yili; Liao, Yi

    2013-01-01

    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 pressure of the gas slip effect in tight sandstones and analyzes the characteristic parameter of capillary pressure curves. The experimental results indicate that gas slip effect can be eliminated when the backpressure reaches a limit pressure. When the backpressure exceeds the limit pressure, 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 pressure increases with the decreasing in permeability and has close relation with pore 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

  17. Pore water pressure variations in Subpermafrost groundwater : Numerical modeling compared with experimental modeling

    NASA Astrophysics Data System (ADS)

    Rivière, Agnès.; Goncalves, Julio; Jost, Anne; Font, Marianne

    2010-05-01

    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 pressurization 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 pore water pressure 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

  18. Abnormal pressure study in the Malay and Penyu Basins: A regional understanding

    SciTech Connect

    Kader, M.S.; Leslie, W.

    1994-07-01

    A majority of wells drilled in the Malay and Penyu basins were terminated due to abnormal pressure. 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 abnormal pressure predictive method used is pressure vs. depth plots of data obtained from Repeat Formation tester (RFT) readings. The study results indicate that abnormal pressure 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 pressured. The onset of abnormal pressure appears to be abrupt in the northern portion and more gradual in the southern part of the Malay Basin. Abnormal pressure in the Malay Basin is found to be neither depth dependent nor age related. Many factors can cause the abnormal formation pressures. 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

  19. Pore-Lining Composition and Capillary Breakthrough Pressure of Mudstone Caprocks: Sealing Efficiency of Geologic CO2 Storage Sites

    NASA Astrophysics Data System (ADS)

    Heath, J. E.; Dewers, T. A.; McPherson, B. J.; Kotula, P. G.

    2010-12-01

    Subsurface containment of CO2 is predicated on effective caprock sealing. Many previous studies have relied on macroscopic measurements of capillary breakthrough pressure and other petrophysical properties without direct examination of solid phases that line pore networks and directly contact fluids. However, pore-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 pore-lining phases of several continental and marine mudstones indicates that sealing efficiency (i.e., breakthrough pressure) is governed by pore shapes and pore-lining phases that are not identifiable except through direct characterization of pores. Bulk X-ray diffraction data does not indicate which phases line the pores and may be especially lacking for mudstones with organic material. Organics can line pores and may represent once-mobile phases that modify the wettability of an originally clay-lined pore network. For shallow formations (i.e., < ~800 m depth), interfacial tension and contact angles result in breakthrough pressures 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.

  20. Irreversible xenon insertion into a small-pore zeolite at moderate pressures and temperatures

    DOE PAGES

    Seoung, Donghoon; Cynn, Hyunchae; Park, Changyong; ...

    2014-09-01

    Pressure 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-pressure chemistry of xenon, which is known to react with hydrogen and ice at high pressures 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 » pores of this zeolite after pressure 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

  1. A thermodynamically consistent model for granular-fluid mixtures considering pore pressure evolution and hypoplastic behavior

    NASA Astrophysics Data System (ADS)

    Hess, Julian; Wang, Yongqi

    2016-11-01

    A new mixture model for granular-fluid flows, which is thermodynamically consistent with the entropy principle, is presented. The extra pore pressure described by a pressure 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 pressure to describe the pressure-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.

  2. Impact of fluid injection velocity on CO2 saturation and pore pressure in porous sandstone

    NASA Astrophysics Data System (ADS)

    Kitamura, Keigo; Honda, Hiroyuki; Takaki, Shinnosuke; Imasato, Mitsunori; Mitani, Yasuhiro

    2017-04-01

    The elucidation of CO2 behavior in sandstone is an essential issue to understand the fate of injecting CO2 in reservoirs. Injected CO2 invades pore 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 pore fluid pressure(Pp) and makes various types of CO2 distribution pattern in pore space. The estimation of SCO_2 in the reservoir is one of important task in CCS projects. Fluid pressure (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 pressure: 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

  3. Effect of Time-Dependent Pinning Pressure on Abnormal Grain Growth: Phase Field Simulation

    NASA Astrophysics Data System (ADS)

    Kim, Jeong Min; Min, Guensik; Shim, Jae-Hyeok; Lee, Kyung Jong

    2018-05-01

    The effect of the time-dependent pinning pressure of precipitates on abnormal grain growth has been investigated by multiphase field simulation with a simple precipitation model. The application of constant pinning pressure is problematic because it always induces abnormal grain growth or no grain growth, which is not reasonable considering the real situation. To produce time-dependent pinning pressure, both precipitation kinetics and precipitate coarsening kinetics have been considered with two rates: slow and fast. The results show that abnormal grain growth is suppressed at the slow precipitation rate. At the slow precipitation rate, the overall grain growth caused by the low pinning pressure in the early stage indeed plays a role in preventing abnormal grain growth by reducing the mobility advantage of abnormal grains. In addition, the fast precipitate coarsening rate tends to more quickly transform abnormal grain growth into normal grain growth by inducing the active growth of grains adjacent to the abnormal grains in the early stage. Therefore, the present study demonstrates that the time dependence of the pinning pressure of precipitates is a critical factor that determines the grain growth mode.

  4. Effect of Time-Dependent Pinning Pressure on Abnormal Grain Growth: Phase Field Simulation

    NASA Astrophysics Data System (ADS)

    Kim, Jeong Min; Min, Guensik; Shim, Jae-Hyeok; Lee, Kyung Jong

    2018-03-01

    The effect of the time-dependent pinning pressure of precipitates on abnormal grain growth has been investigated by multiphase field simulation with a simple precipitation model. The application of constant pinning pressure is problematic because it always induces abnormal grain growth or no grain growth, which is not reasonable considering the real situation. To produce time-dependent pinning pressure, both precipitation kinetics and precipitate coarsening kinetics have been considered with two rates: slow and fast. The results show that abnormal grain growth is suppressed at the slow precipitation rate. At the slow precipitation rate, the overall grain growth caused by the low pinning pressure in the early stage indeed plays a role in preventing abnormal grain growth by reducing the mobility advantage of abnormal grains. In addition, the fast precipitate coarsening rate tends to more quickly transform abnormal grain growth into normal grain growth by inducing the active growth of grains adjacent to the abnormal grains in the early stage. Therefore, the present study demonstrates that the time dependence of the pinning pressure of precipitates is a critical factor that determines the grain growth mode.

  5. Pore Pressure Pulse Drove the 2012 Emilia (Italy) Series of Earthquakes

    NASA Astrophysics Data System (ADS)

    Pezzo, Giuseppe; De Gori, Pasquale; Lucente, Francesco Pio; Chiarabba, Claudio

    2018-01-01

    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 Vp/Vs changes along the fault system suggests that natural pore pressure pulse drove the space-time evolution of seismicity and the activation of the second main shock.

  6. Measuring the effects of pore-pressure changes on seismic amplitude using crosswell continuous active-source seismic monitoring (CASSM)

    SciTech Connect

    Marchesini, Pierpaolo; Daley, Thomas; Ajo-Franklin, Jonathan

    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 pore fluid pressure). 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 pore fluid pressure 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 pore pressure (increasing effective stress).« less

  7. Permeability changes induced by microfissure closure and opening in tectonized materials. Effect on slope pore pressure regime.

    NASA Astrophysics Data System (ADS)

    De la Fuente, Maria; Vaunat, Jean; Pedone, Giuseppe; Cotecchia, Federica; Sollecito, Francesca; Casini, Francesca

    2015-04-01

    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 pore pressure regime in slopes. In this work, the pore pressure 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 Pore 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 pores in the sample and its evolution under external actions. Moreover, comparison of pore 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 pore pressure 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 pore pressure regime.

  8. Modeling of Permeability Structure Using Pore Pressure and Borehole Strain Monitoring

    NASA Astrophysics Data System (ADS)

    Kano, Y.; Ito, H.

    2011-12-01

    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 pore pressure to natural loading such as barometric pressure 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 pore pressure

  9. Dependencies of pore pressure on elastic wave velocities and Vp/Vs ratio for thermally cracked gabbro

    NASA Astrophysics Data System (ADS)

    Nishimura, K.; Uehara, S. I.; Mizoguchi, K.

    2015-12-01

    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 pore pressure 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 pore pressure 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 pressure are 0.5, 3.4 and 3.5%, respectively. Measurements were conducted at a constant confining pressure of 50 MPa, with decreasing pore pressure from 49 to 0.1 MPa and then increasing to 49 MPa. While Vp/Vs for the intact specimen is almost constant at elevated pore pressure, the Vp/Vs values for the thermally cracked ones were 2.0~2.2 when pore pressure 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).

  10. 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://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/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('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/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/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/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/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/scitech">SciTech Connect</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/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('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/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> </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/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://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/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/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/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('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/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('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.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/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/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('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/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('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('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('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> <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/scitech">SciTech Connect</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('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('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> </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('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/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('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://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/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('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('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('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://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('https://rosap.ntl.bts.gov/view/dot/27987','DOTNTL'); return false;" href="https://rosap.ntl.bts.gov/view/dot/27987"><span>An investigation of rock fall and <span class="hlt">pore</span> water <span class="hlt">pressure</span> using LIDAR in Highway 63 rock cuts.</span></a></p> <p><a target="_blank" href="http://ntlsearch.bts.gov/tris/index.do">DOT National Transportation Integrated Search</a></p> <p></p> <p>2014-07-01</p> <p>The purpose of this research work is compare LIDAR scanning measurements of rock fall with the natural changes in groundwater level to determining the effect of water <span class="hlt">pressures</span> (levels) on rock fall. To collect the information of rock cut volume chan...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.fs.usda.gov/treesearch/pubs/7797','TREESEARCH'); return false;" href="https://www.fs.usda.gov/treesearch/pubs/7797"><span>Changes in soil moisture and <span class="hlt">pore</span> <span class="hlt">pressure</span> after harvesting a forested hillslope in northern California</span></a></p> <p><a target="_blank" href="http://www.fs.usda.gov/treesearch/">Treesearch</a></p> <p>Elizabeth T. Keppeler; Robert R. Ziemer; Peter H. Cafferata</p> <p>1994-01-01</p> <p>Abstract - In 1987, a 0.83-ha zero-order swale was instrumented with 58 pierometers and 25 tensiometers along several hillslope transects. Through 1993, soil moisture conditions were measured by <span class="hlt">pressure</span> transducers connected to a digital data logger recording at 15-minute intervals. In August 1989, the 100-year-old second-growth forest in the swale was felled. Logs...</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/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://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('https://www.osti.gov/biblio/5535415-pore-pressure-diffusion-hydrologic-response-nearly-saturated-thin-landslide-deposits-rainfall','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/5535415-pore-pressure-diffusion-hydrologic-response-nearly-saturated-thin-landslide-deposits-rainfall"><span><span class="hlt">Pore</span> <span class="hlt">pressure</span> diffusion and the hydrologic response of nearly saturated, thin landslide deposits of rainfall</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Haneberg, W.C.</p> <p>1991-11-01</p> <p>Previous workers have correlated slope failures during rainstorms with rainfall intensity, rainfall duration, and seasonal antecedent rainfall. This note shows how such relationships can be interpreted using a periodic steady-state solution to the well-known linear <span class="hlt">pressure</span> diffusion equation. Normalization of the governing equation yields a characteristic response time that is a function of soil thickness, saturated hydraulic conductivity, and pre-storm effective porosity, and which is analogous to the travel time of a piston wetting front. The effects of storm frequency and magnitude are also successfully quantified using dimensionless attenuation factors and lag times.</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('http://adsabs.harvard.edu/abs/2015AGUFM.T13E..03P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AGUFM.T13E..03P"><span><span class="hlt">Pore</span> <span class="hlt">pressure</span> evolution and induced seismicity within the Permian Basin, Southeast New Mexico USA</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Person, M. A.; Zhang, Y.; Mozley, P.; Broadhead, R.; Bilek, S.; Edel, S.</p> <p>2015-12-01</p> <p>We used three-dimensional hydrologic modeling to assess the potential linkages between crystalline basement seismicity (up to M3.2) beneath the Dagger Draw oil field in response to saline water reinjection. Production began in 2004 and preceded an increase in seismicity by about 5 years. Reinjection of produced brines occurred within the basal Ellenberger Group carbonate reservoir (yellow square). Published core permeability measurements for the Ellenberger vary between about 10-15 to 10-12 m2. Evidence for seismicity being triggered by injection include observations that the largest injection rates (> 106 barrels/month) occurred within wells closest to the induced seismicity (red circle about 15 km to the west of the injection well in A-C). Arguing against triggered seismicity is the apparent lack of temporal correlation between peak injection and felt seismicity as well as the extreme depth of the earthquakes (about 10-12 km below land surface). We conducted a numerical sensitivity study in which we varied the permeability of the basal reservoir as well as the crystalline basement rocks over several orders of magnitude. Assuming a crystalline basement permeability of 10-16 m2 and a basal reservoir permeability of 10-13 m2 produced about 50 m of excess heads in the seismogenic crust about 1900 days (D) after injection started. Prior studies suggest that excess heads of only a few meters could induce failure along critically stressed faults. The lag between injection and seismicity can be explained by the time required for the <span class="hlt">pressure</span> envelope to propagate laterally 15 km and downward into the crystalline basement 11 km. Peak injection occurred 1900 days before recent increases in seismicity were observed. Future work will include assessing the potential role of relatively permeable Proterozoic faults in transmitting high fluid <span class="hlt">pressures</span> into the crystalline basement.</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/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/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> </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('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.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('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/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('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('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('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('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('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> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/27537378','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/27537378"><span><span class="hlt">Abnormal</span> Circadian Blood <span class="hlt">Pressure</span> Profile as a Prognostic Marker in Patients with Nonischemic Dilated Cardiomyopathy.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Sawamura, Akinori; Okumura, Takahiro; Takeshita, Kyosuke; Watanabe, Naoki; Kano, Naoaki; Mori, Hiroaki; Fukaya, Kenji; Morimoto, Ryota; Hirashiki, Akihiro; Bando, Yasuko Kureishi; Murohara, Toyoaki</p> <p></p> <p>An <span class="hlt">abnormal</span> circadian blood <span class="hlt">pressure</span> (BP) profile is considered a risk factor for cardiovascular disease. However, its significance in heart failure patients with nonischemic etiology is unknown. Herein, we investigated the prognostic value of a circadian BP profile in patients with nonischemic dilated cardiomyopathy (NIDCM). We enrolled 114 NIDCM patients (76 males, mean age 53.1 years). The percent nighttime BP fall (%NBPF) was defined using ambulatory BP monitoring as a percent decrease in mean systolic BP in nighttime from daytime. All patients were divided into three groups: dipper (%NBPF ≥10), non-dipper (0 ≤ %NBPF < 10), and riser (%NBPF <0). Riser patients had the highest serum creatinine levels (dipper, 0.78 ± 0.20 mg/dl; non-dipper, 0.85 ± 0.21 mg/dl; riser, 0.99 ± 0.23 mg/dl; p = 0.006). In survival analysis, riser patients had the highest cumulative cardiac-related deaths (log-rank, p = 0.001), which was an independent predictor of cardiac-related deaths (hazard ratio, 12.6; 95% confidence interval, 1.76-253; p = 0.01). Multivariate analysis revealed that the norepinephrine level at 24-hour collected urine (24 h U-NE) and the serum creatinine level were independent determinants of %NBPF (adjusted R2 = 0.20; 24 h U-NE, p = 0.0001; serum creatinine, p = 0.04). The riser profile was associated with poor prognosis of NIDCM, which may reflect impaired sympathetic nervous system activity. Evaluating the circadian BP profile may be useful for risk stratification in NIDCM patients. © 2016 S. Karger AG, Basel.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/24477097','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/24477097"><span>Association of parental blood <span class="hlt">pressure</span> with retinal microcirculatory <span class="hlt">abnormalities</span> indicative of endothelial dysfunction in children.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Islam, Muhammad; Jafar, Tazeen H; Bux, Rasool; Hashmi, Shiraz; Chaturvedi, Nish; Hughes, Alun D</p> <p>2014-03-01</p> <p>Microcirculatory <span class="hlt">abnormalities</span> precede the onset of hypertension and may explain its familial nature. We examined the relationship between parental blood <span class="hlt">pressure</span> (BP) and offspring retinal microvasculature in Pakistani trios [father, mother, and child (aged 9-14 years)]. This is a substudy of a population-based trial of BP reduction. Data were available on 358 normotensive, and 410 offspring of at least one hypertensive parent. Retinal vessel characteristics were measured from digital images. Multivariable linear regression models were built to assess the associations between maternal and paternal BP and offspring retinal microvasculature. Optimality deviation was greatest in offspring of two hypertensive parents, compared with those with one or no hypertensive parent (P=0.030 for trend). Paternal SBP and DBP were each significantly associated with optimality deviation in offspring (P=0.023 and P=0.006, respectively). This relationship persisted after accounting for offspring cardiovascular risk factors [increase in optimality deviation (95% confidence interval, CI) 0.0053 (0.0001-0.0106, P=0.047) and 0.0109 (0.0025-0.0193, P=0.011), for each 10 mmHg increase in paternal SBP and DBP, respectively]. Maternal DBP was inversely associated with offspring arteriovenous ratio -0.0102 (-0.0198 to -0.0007, P=0.035). Microvascular endothelial dysfunction in children is associated with increasing levels of parental hypertension. The association with paternal BP is independent of other cardiovascular risk factors, including the child's BP. Higher maternal DBP is associated with evidence of arteriolar narrowing in offspring. These early microcirculatory changes may help explain familial predisposition to hypertension in people of Pakistani origin at an early age. :</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/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('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/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('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/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/2017AGUFM.S43B0872F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017AGUFM.S43B0872F"><span>Simulation of Co-Seismic Off-Fault Stress Effects: Influence of Fault Roughness and <span class="hlt">Pore</span> <span class="hlt">Pressure</span> Coupling</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Fälth, B.; Lund, B.; Hökmark, H.</p> <p>2017-12-01</p> <p>Aiming at improved safety assessment of geological nuclear waste repositories, we use dynamic 3D earthquake simulations to estimate the potential for co-seismic off-fault distributed fracture slip. Our model comprises a 12.5 x 8.5 km strike-slip fault embedded in a full space continuum where we apply a homogeneous initial stress field. In the reference case (Case 1) the fault is planar and oriented optimally for slip, given the assumed stress field. To examine the potential impact of fault roughness, we also study cases where the fault surface has undulations with self-similar fractal properties. In both the planar and the undulated cases the fault has homogeneous frictional properties. In a set of ten rough fault models (Case 2), the fault friction is equal to that of Case 1, meaning that these models generate lower seismic moments than Case 1. In another set of ten rough fault models (Case 3), the fault dynamic friction is adjusted such that seismic moments on par with that of Case 1 are generated. For the propagation of the earthquake rupture we adopt the linear slip-weakening law and obtain Mw 6.4 in Case 1 and Case 3, and Mw 6.3 in Case 2 (35 % lower moment than Case 1). During rupture we monitor the off-fault stress evolution along the fault plane at 250 m distance and calculate the corresponding evolution of the Coulomb Failure Stress (CFS) on optimally oriented hypothetical fracture planes. For the stress-<span class="hlt">pore</span> <span class="hlt">pressure</span> coupling, we assume Skempton's coefficient B = 0.5 as a base case value, but also examine the sensitivity to variations of B. We observe the following: (I) The CFS values, and thus the potential for fracture slip, tend to increase with the distance from the hypocenter. This is in accordance with results by other authors. (II) The highest CFS values are generated by quasi-static stress concentrations around fault edges and around large scale fault bends, where we obtain values of the order of 10 MPa. (III) Locally, fault roughness may have a</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015AGUFMEP13A0927P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AGUFMEP13A0927P"><span>Episodic Sediment Failure in Northern Flemish Pass, Eastern Canadian Margin: Interplay of Seismicity, Contour Current Winnowing, and Excess <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>Piper, D.</p> <p>2015-12-01</p> <p> preconditioned the slope for earthquake triggering. There is circumstantial evidence that such preconditioning is related to excess <span class="hlt">pore</span> <span class="hlt">pressures</span>, released by fluid drainage at head scarps.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018E%26PSL.482...33T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018E%26PSL.482...33T"><span>Fast intraslab fluid-flow events linked to pulses of high <span class="hlt">pore</span> fluid <span class="hlt">pressure</span> at the subducted plate interface</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Taetz, Stephan; John, Timm; Bröcker, Michael; Spandler, Carl; Stracke, Andreas</p> <p>2018-01-01</p> <p>A better understanding of the subduction zone fluid cycle and its chemical-mechanical feedback requires in-depth knowledge about how fluids flow within and out of descending slabs. Relicts of fluid-flow systems in exhumed rocks of fossil subduction zones allow for identification of the general relationships between dehydration reactions, fluid pathway formation, the dimensions and timescales of distinct fluid flow events; all of which are required for quantitative models for fluid-induced subduction zone processes. Two types of garnet-quartz-phengite veins can be distinguished in an eclogite-facies mélange block from the Pouébo Eclogite Mélange, New Caledonia. These veins record synmetamorphic internal fluid release by mineral breakdown reactions (type I veins), and infiltration of an external fluid (type II veins) with the associated formation of a reaction selvage. The dehydration and fluid migration documented by the type I veins likely occurred on a timescale of 105-106 years, based on average subduction rates and metamorphic conditions required for mineral dehydration and fluid flow. The timeframe of fluid-rock interaction between the external fluid and the wall-rock of the type II veins is quantified using a continuous bulk-rock Li-diffusion profile perpendicular to a vein and its metasomatic selvage. Differences in Li concentration between the internal and external fluid reservoirs resulted in a distinct diffusion profile (decreasing Li concentration and increasing δ7 Li) as the reaction front propagated into the host rock. Li-chronometric constraints indicate that the timescales of fluid-rock interaction associated with type II vein formation are on the order of 1 to 4 months (0.150-0.08+0.14 years). The short-lived, pulse-like character of this process is consistent with the notion that fluid flow caused by oceanic crust dehydration at the blueschist-to-eclogite transition contributes to or even dominates episodic <span class="hlt">pore</span> fluid <span class="hlt">pressure</span> increases at the</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/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('http://adsabs.harvard.edu/abs/2018JMMM..453...67C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018JMMM..453...67C"><span>Lattice dynamics, elasticity and magnetic <span class="hlt">abnormality</span> in ordered crystalline alloys Fe3Pt at high <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>Cheng, Tai-min; Yu, Guo-Liang; Su, Yong; Ge, Chong-Yuan; Zhang, Xin-Xin; Zhu, Lin; Li, Lin</p> <p>2018-05-01</p> <p>The ordered crystalline Invar alloy Fe3Pt is in a special magnetic critical state, under which the lattice dynamic stability of the system is extremely sensitive to external <span class="hlt">pressures</span>. We studied the <span class="hlt">pressure</span> dependence of enthalpy and magnetism of Fe3Pt in different crystalline alloys by using the first-principles projector augmented-wave method based on the density functional theory. Results show that the P4/mbm structure is the ground state structure and is more stable relative to other structures at <span class="hlt">pressures</span> below 18.54 GPa. The total magnetic moments of L12, I4/mmm and DO22 structures decrease rapidly with <span class="hlt">pressure</span> and oscillate near the ferromagnetic collapse critical <span class="hlt">pressure</span>. At the <span class="hlt">pressure</span> of 43 GPa, the ferrimagnetic property in DO22 structure becomes apparently strengthened and its volume increases rapidly. The lattice dynamics calculation for L12 structures at high <span class="hlt">pressures</span> shows that the spontaneous magnetization of the system in ferromagnetic states induces the softening of the transverse acoustic phonon TA1 (M), and there exists a strong spontaneous volume magnetostriction at <span class="hlt">pressures</span> below 26.95 GPa. Especially, the lattice dynamics stability is sensitive to <span class="hlt">pressure</span>, in the <span class="hlt">pressure</span> range between the ferromagnetic collapse critical <span class="hlt">pressure</span> (41.9 GPa) and the magnetism completely disappearing <span class="hlt">pressure</span> (57.25 GPa), and near the <span class="hlt">pressure</span> of phase transition from L12 to P4/mbm structure (27.27 GPa). Moreover, the instability of magnetic structure leads to a prominent elastic modulus oscillation, and the spin polarizability of electrons near the Fermi level is very sensitive to <span class="hlt">pressures</span> in that the <span class="hlt">pressure</span> range. The <span class="hlt">pressure</span> induces the stability of the phonon spectra of the system at <span class="hlt">pressures</span> above 57.25 GPa.</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://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('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('https://www.ncbi.nlm.nih.gov/pubmed/12615828','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/12615828"><span><span class="hlt">Abnormal</span> assembly of annulate lamellae and nuclear <span class="hlt">pore</span> complexes coincides with fertilization arrest at the pronuclear stage of human zygotic development.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Rawe, V Y; Olmedo, S Brugo; Nodar, F N; Ponzio, R; Sutovsky, P</p> <p>2003-03-01</p> <p>The assembly of nuclear <span class="hlt">pore</span> complexes (NPC) and their cytoplasmic stacks, annulate lamellae (AL), promote normal nucleocytoplasmic trafficking and accompany pronuclear development within the mammalian zygote. Previous studies showed that a percentage of human oocytes fertilized in vitro failed to develop normal pronuclei and cleave within 40-48 h post insemination. We hypothesized that an aberrant recruitment of NPC proteins, nucleoporins and/or NPC preassembled into AL, might accompany human fertilization arrest. We explored NPC and AL assembly in unfertilized human oocytes, and fertilized and arrested zygotes by immunofluorescence with an NPC- and AL-specific antibody, mAb 414, and by transmission electron microscopy. Major NPC or AL assembly was not observed in the unfertilized human oocytes. Once fertilization took place, the formation of AL was observed throughout the cytoplasm and near the developing pronuclei with NPC. On the contrary, NPC assembly was disrupted in the arrested zygotes, whereas AL were clustered into large sheaths. This was accompanied by the lack of NPC incorporation into the nuclear envelopes. We conclude that the aberrant assembly of NPC and AL coincides with early developmental failure in humans.</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> <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.ncbi.nlm.nih.gov/pubmed/22595397','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/22595397"><span>Contribution of autonomic dysfunction to <span class="hlt">abnormal</span> exercise blood <span class="hlt">pressure</span> in 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>Weston, Kassia S; Sacre, Julian W; Jellis, Christine L; Coombes, Jeff S</p> <p>2013-01-01</p> <p>The purpose of this study was to compare the presence and severity of autonomic dysfunction in type 2 diabetes mellitus patients, with and without exaggerated blood <span class="hlt">pressure</span> responses to exercise. We performed a cross-sectional analysis of 98 patients with type 2 diabetes mellitus (aged 59±9). Both time (standard deviation of RR intervals, root-mean-square of successive RR interval differences) and frequency (total spectral power, high frequency, low frequency, very low frequency) domains of heart rate variability were analysed in a 5 min recording at rest and 20 min after a maximal treadmill test. An exaggerated blood <span class="hlt">pressure</span> response to exercise was identified by peak blood <span class="hlt">pressure</span> ≥190/105 mmHg (women) or ≥210/105 mmHg (men). Each group of either exaggerated exercise blood <span class="hlt">pressure</span> response or normal blood <span class="hlt">pressure</span> response consisted of 49 patients. At rest there were no significant differences between groups for all time and frequency domain parameters of heart rate variability. Post-exercise, there was a significant (p<0.05) reduction in the SDNN, RMSSD and TP in the exaggerated exercise blood <span class="hlt">pressure</span> group. Independent correlates (p<0.01) of exercise systolic blood <span class="hlt">pressure</span> included post-exercise TP, resting systolic blood <span class="hlt">pressure</span>, cardiac autonomic neuropathy and beta-blockers (beta=-0.28, adj. R² = 0.32, p<0.001). Reduced post-exercise heart rate variability in patients with type 2 diabetes mellitus, with an exaggerated exercise blood <span class="hlt">pressure</span> response suggests preclinical autonomic dysfunction characterized by impaired vagal modulation. Copyright © 2012 Sports Medicine Australia. Published by Elsevier Ltd. All rights reserved.</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('https://www.ncbi.nlm.nih.gov/pubmed/3403832','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/3403832"><span>Increased intracranial <span class="hlt">pressure</span> elicits hypertension, increased sympathetic activity, electrocardiographic <span class="hlt">abnormalities</span> and myocardial damage in rats.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Shanlin, R J; Sole, M J; Rahimifar, M; Tator, C H; Factor, S M</p> <p>1988-09-01</p> <p>Intracranial <span class="hlt">pressure</span> was increased in 59 rats by inflating a subdural balloon to a total mass volume of 0.3 ml. The increase in intracranial <span class="hlt">pressure</span> ranged from 75 to greater than 500 mm Hg. With few exceptions, mean arterial <span class="hlt">pressure</span> increased to as high as 227 mm Hg during the increase in intracranial <span class="hlt">pressure</span>. Significant increases in plasma catecholamines, major electrocardiographic changes and a considerably shortened survival time were observed only in the rats that demonstrated an increase in mean arterial <span class="hlt">pressure</span> greater than 50 mm Hg. A perfusion study with liquid silicone rubber (Microfil) revealed dilated irregular myocardial vessels with areas of focal constriction consistent with microvascular spasm. Histologic examination of the myocardium revealed widespread patches of contraction band necrosis and occasional contraction bands in the smooth muscle media of large coronary arteries. These observations suggest that myocardial damage after suddenly increased intracranial <span class="hlt">pressure</span> resulted both from exposure to toxic levels of catecholamines and from myocardial reperfusion. Extension of these studies to humans suggests that a detailed assessment of myocardial function should be performed in victims of severe brain injury. Myocardial dysfunction may be a major determinant of the patient's prognosis or may render the heart unsuitable for transplantation.</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('http://adsabs.harvard.edu/abs/2017MMI....23..336K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017MMI....23..336K"><span>Effects of particle size and forming <span class="hlt">pressure</span> on <span class="hlt">pore</span> properties of Fe-Cr-Al porous metal by pressureless sintering</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Koo, Bon-Uk; Yi, Yujeong; Lee, Minjeong; Kim, Byoung-Kee</p> <p>2017-03-01</p> <p>With increased hydrogen consumption in ammonia production, refining and synthesis, fuel cells and vehicle industries, development of the material components related to hydrogen production is becoming an important factor in industry growth. Porous metals for fabrication of hydrogen are commonly known for their relative excellence in terms of large area, lightness, lower heat capacity, high toughness, and permeability. Fe-Cr-Al alloys not only have high corrosion resistance, heat resistance, and chemical stability but also ductility, excellent mechanical properties. In order to control powder size and sintering temperature effects of Fe-Cr-Al porous metal fabrication, Fe-Cr-Al powder was classified into 25-35 μm, 35-45 μm, 45-75 μm using an auto shaking sieve machine and then classified Fe-Cr-Al powders were pressed into disk shapes using a uniaxial press machine and CIP. The pelletized Fe-Cr-Al specimens were sintered at various temperatures in high vacuum. Properties such as <span class="hlt">pore</span> size, porosity, and air permeability were evaluated using perm-porosimetry. Microstructure and phase changes were observed with SEM and XRD. Porosity and relative density were proportionated to increasing sintering temperature. With sufficient sintering at increasing temperatures, the <span class="hlt">pore</span> size is expected to be gradually reduced. Porosity decreased with increasing sintering temperature and gradually increased necking of the powder.</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.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('https://eric.ed.gov/?q=Blood+AND+pressure&pg=3&id=EJ1019815','ERIC'); return false;" href="https://eric.ed.gov/?q=Blood+AND+pressure&pg=3&id=EJ1019815"><span>Increasing Body Mass Index, Blood <span class="hlt">Pressure</span>, and Acanthosis Nigricans <span class="hlt">Abnormalities</span> in School-Age Children</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>Otto, Debra E.; Wang, Xiaohui; Garza, Viola; Fuentes, Lilia A.; Rodriguez, Melinda C.; Sullivan, Pamela</p> <p>2013-01-01</p> <p>This retrospective quantitative study examined the relationships among gender, Acanthosis Nigricans (AN), body mass index (BMI), and blood <span class="hlt">pressure</span> (BP) in children attending school Grades 1-9 in Southwest Texas. Of the 34,897 health screening records obtained for the secondary analysis, 32,788 were included for the study. A logistic regression…</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/25790276','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/25790276"><span><span class="hlt">Abnormal</span> intra-aural <span class="hlt">pressure</span> waves associated with death in African children with acute nontraumatic coma.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Gwer, Samson; Kazungu, Michael; Chengo, Eddie; Ohuma, Eric O; Idro, Richard; Birch, Tony; Marchbanks, Robert; Kirkham, Fenella J; Newton, Charles R</p> <p>2015-07-01</p> <p>We explored the relationship between tympanic membrane displacement (TMD) measurements, a tool to monitor intracranial <span class="hlt">pressure</span> noninvasively, and clinical features and death in children with acute coma in Kilifi, Kenya. Between November 2007 and September 2009, we made serial TMD measurements and clinical observations on children with acute coma (Blantyre coma score (BCS) ≤ 2) on the pediatric high dependency unit of Kilifi District Hospital, and on well children presenting to the hospital's outpatient department for routine follow-up. We examined middle ear function using tympanometry and measured cardiac pulse (CPA) and respiratory pulse <span class="hlt">pressure</span> amplitudes (RPA) using the TMD analyzer. We recruited 75 children (32 (43%) females; median age 3.3 (IQR: 2.0, 4.3) years). Twenty-one (28%) children died. Higher TMD measurements predicted death. Adjusting for diagnosis, every 50 nl rise in both semirecumbent and recumbent CPA was associated with increased odds of death associated with intracranial herniation (OR: 1.61, 95% confidence interval (CI): 1.07, 2.41; P = 0.02 and OR: 1.35, 95% CI: 1.10, 1.66; P ≤ 0.01 respectively). Raised TMD pulse <span class="hlt">pressure</span> measurements are associated with death and may be useful in detecting and monitoring risk of intracranial herniation and intracranial <span class="hlt">pressure</span> in childhood coma.</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/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> </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('https://www.ncbi.nlm.nih.gov/pubmed/28743415','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/28743415"><span>Colour vision <span class="hlt">abnormality</span> as the only manifestation of normal <span class="hlt">pressure</span> hydrocephalus.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Asensio-Sánchez, V M; Martín-Prieto, A</p> <p>2018-01-01</p> <p>The case is presented of a 73-year-old male patient who referred to having black and white vision. Computed tomography showed normal <span class="hlt">pressure</span> hydrocephalus (NPH). Magnetic resonance imaging was not performed because the patient refused to undergo further examinations. Achromatopsia may be the first or only NPH symptom. It may be prudent to ask patients with NPH regarding colour vision. Copyright © 2017 Sociedad Española de Oftalmología. Publicado por Elsevier España, S.L.U. All rights reserved.</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/scitech">SciTech Connect</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('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=2704919','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=2704919"><span>Why continued surveillance? Intermittent blood <span class="hlt">pressure</span> and heart rate <span class="hlt">abnormality</span> under treatment</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Katinas, G. S.; Cornélissen, G.; Otsuka, K.; Haus, E.; Bakken, E. E.; Halberg, F.</p> <p>2008-01-01</p> <p>Several opinion leaders have monitored their blood <span class="hlt">pressure</span> systematically a sufficient number of times a day for chronomic (time structural) analyses, from the time of encountering chronobiology until their death; they set an example for others who also may not wish to base treatment on single spotchecks in a health care office. Such self-measurements, while extremely helpful, were not readily feasible without a noteworthy interruption of activities during waking as well as of sleep. New, relatively unobtrusive instrumentation now makes monitoring possible and cost-effective and will save lives. Illustrative results and problems encountered in an as-one-goes self-survey by GSK, a physician-scientist, are presented herein. Both MESOR-hypertension and CHAT (circadian hyper-amplitude-tension) can be intermittent conditions even under treatment, and treatment is best adjusted based on monitoring, rather than “flying blind”. PMID:16275483</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> <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('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('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/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('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('https://www.ncbi.nlm.nih.gov/pubmed/24932757','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/24932757"><span>Melatonin secretion is impaired in women with preeclampsia and an <span class="hlt">abnormal</span> circadian blood <span class="hlt">pressure</span> rhythm.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Bouchlariotou, Sofia; Liakopoulos, Vassilios; Giannopoulou, Myrto; Arampatzis, Spyridon; Eleftheriadis, Theodoros; Mertens, Peter R; Zintzaras, Elias; Messinis, Ioannis E; Stefanidis, Ioannis</p> <p>2014-08-01</p> <p>Non-dipping circadian blood <span class="hlt">pressure</span> (BP) is a common finding in preeclampsia, accompanied by adverse outcomes. Melatonin plays pivotal role in biological circadian rhythms. This study investigated the relationship between melatonin secretion and circadian BP rhythm in preeclampsia. Cases were women with preeclampsia treated between January 2006 and June 2007 in the University Hospital of Larissa. Volunteers with normal pregnancy, matched for chronological and gestational age, served as controls. Twenty-four hour ambulatory BP monitoring was applied. Serum melatonin and urine 6-sulfatoxymelatonin levels were determined in day and night time samples by enzyme-linked immunoassays. Measurements were repeated 2 months after delivery. Thirty-one women with preeclampsia and 20 controls were included. Twenty-one of the 31 women with preeclampsia were non-dippers. Compared to normal pregnancy, in preeclampsia there were significantly lower night time melatonin (48.4 ± 24.7 vs. 85.4 ± 26.9 pg/mL, p<0.001) levels. Adjustment for circadian BP rhythm status ascribed this finding exclusively to non-dippers (p<0.01). Two months after delivery, in 11 of the 21 non-dippers both circadian BP and melatonin secretion rhythm reappeared. In contrast, in cases with retained non-dipping status (n=10) melatonin secretion rhythm remained impaired: daytime versus night time melatonin (33.5 ± 13.0 vs. 28.0 ± 13.8 pg/mL, p=0.386). Urinary 6-sulfatoxymelatonin levels were, overall, similar to serum melatonin. Circadian BP and melatonin secretion rhythm follow parallel course in preeclampsia, both during pregnancy and, at least 2 months after delivery. Our findings may be not sufficient to implicate a putative therapeutic effect of melatonin, however, they clearly emphasize that its involvement in the pathogenesis of a non-dipping BP in preeclampsia needs intensive further investigation.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/24047218','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/24047218"><span>Depression and anxiety are associated with <span class="hlt">abnormal</span> nocturnal blood <span class="hlt">pressure</span> fall in hypertensive patients.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Sunbul, Murat; Sunbul, Esra Aydin; Kosker, Selcen Dogru; Durmus, Erdal; Kivrak, Tarik; Ileri, Cigdem; Oguz, Mustafa; Sari, Ibrahim</p> <p>2014-01-01</p> <p>Previous studies have shown that depression and anxiety were independent risk factors for hypertension. Non-dipper hypertension is associated with higher cardiovascular mortality. The aim of this study was to evaluate the anxiety and depression scores in patients with dipper and non-dipper hypertension. The study sample consisted of 153 hypertensive patients. All patients underwent 24-h blood <span class="hlt">pressure</span> monitoring. Patients were classified into two groups according to their dipper or non-dipper hypertension status. We evaluated results of the Hospital Anxiety and Depression Scale between groups. Seventy-eight patients (38 male, mean age: 51.6 ± 12.5 years) had dipper hypertension while 75 patients (27 male, mean age: 55.4 ± 14.1 years) had non-dipper hypertension (p = 0.141, 0.072, respectively). Clinical characteristics were similar for both groups. Patients with non-dipper hypertension had significantly higher depression and anxiety scores compared to patients with dipper hypertension. Dipper and non-dipper status significantly correlated with anxiety (p: 0.025, r: 0.181) and depression score (p: 0.001, r: 0.255). In univariate analysis, smoking, alcohol usage, presence of diabetes, hyperlipidemia, anxiety score >8 and depression score >7 were predictors of dipper versus non-dipper status. In multivariate logistic regression analyses only depression score >7 was independent predictor of dipper versus non-dipper status (odds ratio: 2.74, confidence intervals: 1.41-5.37). A depression score of 7 or higher predicted non-dipper status with a sensitivity of 62.7% and specificity of 62.8%. Non-dipper patients have significantly higher anxiety and depression scores compared to dipper patients. Evaluation of anxiety and depression in patients with hypertension might help to detect non-dipper group and hence guide for better management.</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('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/2009JGRB..114.5405S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2009JGRB..114.5405S"><span>Determination of the <span class="hlt">pore</span> fluid <span class="hlt">pressure</span> ratio at seismogenic megathrusts in subduction zones: Implications for strength of asperities and Andean-type mountain building</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Seno, Tetsuzo</p> <p>2009-05-01</p> <p>We construct the differential stress profile across the fore arc in a subduction zone from the force balance between the shear stress, τ, at seismogenic megathrust and the lithostatic <span class="hlt">pressure</span>. We assume that τ is written by μ (1 - λ) σn, where λ is the <span class="hlt">pore</span> fluid <span class="hlt">pressure</span> ratio, μ is the coefficient of static friction, and σn is the normal stress. Given a density structure of the fore-arc wedge, we determine λ by comparing calculated fore-arc stresses with observed ones, as 0.95-0.98 in Shikoku, Miyagi, Peru, north Chile, and south Chile and 0.90-0.93 in south Vancouver Island and Washington. The parameter τ averaged over the seismogenic megathrust is of the order of ˜10 MPa. Stress drops of great earthquakes in these zones occupy 14-87% and not a constant fraction of τ. They, on the other hand, increase linearly with 1 - λ. We propose a simple fault model in which the area of asperities as a fraction of the total fault area is proportional to 1 - λ. Variation of fractional area of asperities thus may explain the observed correlation and the regional variation of λ. Assuming that the differential stress at summit of the Andean mountains is zero, not at the coast as observed at present, we determine λ to be 0.84 in north Chile in the mountain building stage. Such a smaller value of λ, along with λ < ˜0.4 in collision zones previously obtained and >˜0.9 in subduction zones, would suggest that variation of λ controls the tectonic style of the Earth.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015GGG....16.1089L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015GGG....16.1089L"><span>The impact of splay faults on fluid flow, solute transport, and <span class="hlt">pore</span> <span class="hlt">pressure</span> distribution in subduction zones: A case study offshore the Nicoya Peninsula, Costa Rica</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Lauer, Rachel M.; Saffer, Demian M.</p> <p>2015-04-01</p> <p>Observations of seafloor seeps on the continental slope of many subduction zones illustrate that splay faults represent a primary hydraulic connection to the plate boundary at depth, carry deeply sourced fluids to the seafloor, and are in some cases associated with mud volcanoes. However, the role of these structures in forearc hydrogeology remains poorly quantified. We use a 2-D numerical model that simulates coupled fluid flow and solute transport driven by fluid sources from tectonically driven compaction and smectite transformation to investigate the effects of permeable splay faults on solute transport and <span class="hlt">pore</span> <span class="hlt">pressure</span> distribution. We focus on the Nicoya margin of Costa Rica as a case study, where previous modeling and field studies constrain flow rates, thermal structure, and margin geology. In our simulations, splay faults accommodate up to 33% of the total dewatering flux, primarily along faults that outcrop within 25 km of the trench. The distribution and fate of dehydration-derived fluids is strongly dependent on thermal structure, which determines the locus of smectite transformation. In simulations of a cold end-member margin, smectite transformation initiates 30 km from the trench, and 64% of the dehydration-derived fluids are intercepted by splay faults and carried to the middle and upper slope, rather than exiting at the trench. For a warm end-member, smectite transformation initiates 7 km from the trench, and the associated fluids are primarily transmitted to the trench via the décollement (50%), and faults intercept only 21% of these fluids. For a wide range of splay fault permeabilities, simulated fluid <span class="hlt">pressures</span> are near lithostatic where the faults intersect overlying slope sediments, providing a viable mechanism for the formation of mud volcanoes.</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/2017EGUGA..1912617T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017EGUGA..1912617T"><span>Fast fluid-flow events within a subduction-related vein system in oceanic eclogite: implications for <span class="hlt">pore</span> fluid <span class="hlt">pressure</span> at the plate interface</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Taetz, Stephan; John, Timm; Bröcker, Michael; Spandler, Carl; Stracke, Andreas</p> <p>2017-04-01</p> <p> been completed within ca. 3 years. The short-lived, pulse-like character of this process is in accordance with the notion that fluid flow related to oceanic crust dehydration at the blueschist-to-eclogite transition contributes to or even dominates episodic <span class="hlt">pore</span> fluid <span class="hlt">pressure</span> increases at the plate interface which may trigger slip events reported from many subduction zones.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015EGUGA..17.3757A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015EGUGA..17.3757A"><span>Accounting for <span class="hlt">pore</span> water <span class="hlt">pressure</span> and confined aquifers in assessing the stability of slopes: a Limit Equilibrium analysis carried out through the Minimum Lithostatic Deviation method</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ausilia Paparo, Maria; Tinti, Stefano</p> <p>2015-04-01</p> <p>The model we introduce is an implementation of the Minimum Lithostatic Deviation (MLD) method, developed by Tinti and Manucci (Tinti and Manucci 2006; 2008), that makes use of the limit equilibrium (LE) theory to estimate the stability of a slope. The main purpose here is to analyse the role of a confined aquifer on the value of the Safety Factor (F), the parameter that in the LE is used to determine if a slope is stable or unstable. The classical LE methods treat unconfined aquifers by including the water <span class="hlt">pore</span> <span class="hlt">pressure</span> in the Mohr-Coulomb failure formula: since the water decreases the friction shear strength, the soil above the sliding surface turns out to be more prone to instability. In case of a confined aquifer, however, due to a presence of impermeable layers, the water is not free to flow into the matrix of the overlying soil. We consider here the assumption of a permeable soil sliding over an impermeable layer, which is an occurrence that is found in several known landslide cases (e.g. Person, 2008; Strout and Tjeltja, 2008; Morgan et al., 2010 for offshore slides; and Palladino and Peck, 1972; Miller and Sias, 1998; Jiao et al. 2005; Paparo et al., 2013 for slopes in proximity of artificial or natural water basins) where clay beds form the potential sliding surface: the water, confined below, pushes along these layers and acts on the sliding body as an external bottom load. We modify the MLD method equations in order to take into account the load due to a confined aquifer and apply the new model to the Vajont case, where many have hypothesised the contribution of a confined aquifer to the failure. Our calculations show that the rain load i) infiltrating directly into the soil body and ii) penetrating into the confined aquifer below the clay layers, in addition with the lowering of the reservoir level, were key factors of destabilization of the Mt Toc flank and caused the disastrous landslide.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014AGUFM.S53C4544M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014AGUFM.S53C4544M"><span>Geometry and <span class="hlt">Pore</span> <span class="hlt">Pressure</span> Shape the Pattern of the Tectonic Tremors Activity on the Deep San Andreas Fault with Periodic, Period-Multiplying Recurrence Intervals</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Mele Veedu, D.; Barbot, S.</p> <p>2014-12-01</p> <p>A never before recorded pattern of periodic, chaotic, and doubled, earthquake recurrence intervals was detected in the sequence of deep tectonic tremors of the Parkfield segment of the San Andreas Fault (Shelly, 2010). These observations may be the most puzzling seismological observations of the last decade: The pattern was regularly oscillating with a period doubling of 3 and 6 days from mid-2003 until it was disrupted by the 2004 Mw 6.0 Parkfield earthquake. But by the end of 2007, the previous pattern resumed. Here, we assume that the complex dynamics of the tremors is caused by slip on a single asperity on the San Andreas Fault with homogeneous friction properties. We developed a three-dimensional model based on the rate-and-state friction law with a single patch and simulated fault slip during all stages of the earthquake cycle using the boundary integral method of Lapusta & Liu (2009). We find that homogeneous penny-shaped asperities cannot induce the observed period doubling, and that the geometry itself of the velocity-weakening asperity is critical in enabling the characteristic behavior of the Parkfield tremors. We also find that the system is sensitive to perturbations in <span class="hlt">pore</span> <span class="hlt">pressure</span>, such that the ones induced by the 2004 Parkfield earthquake are sufficient to dramatically alter the dynamics of the tremors for two years, as observed by Shelly (2010). An important finding is that tremor magnitude is amplified more by macroscopic slip duration on the source asperity than by slip amplitude, indicative of a time-dependent process for the breakage of micro-asperities that leads to seismic emissions. Our simulated event duration is in the range of 25 to 150 seconds, closely comparable to the event duration of a typical Parkfield tectonic tremor. Our simulations reproduce the unique observations of the Parkfield tremor activity. This study vividly illustrates the critical role of geometry in shaping the dynamics of fault slip evolution on a seismogenic fault.</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> </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('http://adsabs.harvard.edu/abs/2009Tectp.476..180B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2009Tectp.476..180B"><span>Active stress from earthquake focal mechanisms along the Padan-Adriatic side of the Northern Apennines (Italy), with considerations on stress magnitudes and <span class="hlt">pore</span>-fluid <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>Boncio, Paolo; Bracone, Vito</p> <p>2009-10-01</p> <p>The active tectonic regime along the outer Northern Apennines (Padan-Adriatic area) is a matter of debate. We analyse the active tectonic regime by systematically inverting earthquake focal mechanisms in terms of their driving stress field, comparing two different stress inversion methods. Earthquakes within the area often deviate from Andersonian conditions, being characterized by reverse or transpressional slip on high-angle faults even if the regime is almost purely thrust faulting (e.g. Reggio Emilia 1996 and Faenza 2000 earthquakes). We analyse the stress conditions at faulting for the Reggio Emilia and Faenza earthquakes in order to infer the stress magnitudes and the possible role of fluid <span class="hlt">pressures</span>. The stress analysis defines a consistent pattern of sub-horizontal active deviatoric compression arranged nearly perpendicular to the eastern front of the Padan-Adriatic fold-and-thrust system, independent of the stress inversion method used. The results are consistent with active compression operating within the Padan-Adriatic belt. The stress field is thrust faulting (sub-vertical σ3), except for the Cesena-Forlì and Ancona areas, where a strike-slip regime (sub-vertical or steeply-plunging σ2) operates. The strike-slip regimes are interpreted as being caused by the superposition of local tensional stresses due to oroclinal bending (i.e. rotations of the belt about vertical axes) on the regional compressional stress field. Kinematic complexities characterize the 1996 Reggio Emilia seismic sequence. The distribution of these complexities is not random, suggesting that they are due to local variations of the regional stress field within the unfaulted rocks surrounding the coseismic rupture. The stress conditions at faulting for the Reggio Emilia 1996 and Faenza 2000 earthquakes, coupled with the observation that seismicity in the Padan-Adriatic area often occurs in swarms, suggest that high <span class="hlt">pore</span>-fluid <span class="hlt">pressures</span> (Pf ≥ 70% of the lithostatic load) operate</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/2015SolE....6..553D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015SolE....6..553D"><span>Syn-eruptive, soft-sediment deformation of deposits from dilute pyroclastic density current: triggers from granular shear, dynamic <span class="hlt">pore</span> <span class="hlt">pressure</span>, ballistic impacts and shock waves</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Douillet, G. A.; Taisne, B.; Tsang-Hin-Sun, E.; Muller, S. K.; Kueppers, U.; Dingwell, D. B.</p> <p>2015-05-01</p> <p>Soft-sediment deformation structures can provide valuable information about the conditions of parent flows, the sediment state and the surrounding environment. Here, examples of soft-sediment deformation in deposits of dilute pyroclastic density currents are documented and possible syn-eruptive triggers suggested. Outcrops from six different volcanoes have been compiled in order to provide a broad perspective on the variety of structures: Soufriere Hills (Montserrat), Tungurahua (Ecuador), Ubehebe craters (USA), Laacher See (Germany), and Tower Hill and Purrumbete lakes (both Australia). The variety of features can be classified in four groups: (1) tubular features such as pipes; (2) isolated, laterally oriented deformation such as overturned or oversteepened laminations and vortex-shaped laminae; (3) folds-and-faults structures involving thick (>30 cm) units; (4) dominantly vertical inter-penetration of two layers such as potatoids, dishes, or diapiric flame-like structures. The occurrence of degassing pipes together with basal intrusions suggest fluidization during flow stages, and can facilitate the development of other soft-sediment deformation structures. Variations from injection dikes to suction-driven, local uplifts at the base of outcrops indicate the role of dynamic <span class="hlt">pore</span> <span class="hlt">pressure</span>. Isolated, centimeter-scale, overturned beds with vortex forms have been interpreted to be the signature of shear instabilities occurring at the boundary of two granular media. They may represent the frozen record of granular, pseudo Kelvin-Helmholtz instabilities. Their recognition can be a diagnostic for flows with a granular basal boundary layer. Vertical inter-penetration and those folds-and-faults features related to slumps are driven by their excess weight and occur after deposition but penecontemporaneous to the eruption. The passage of shock waves emanating from the vent may also produce trains of isolated, fine-grained overturned beds that disturb the surface bedding</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014SolED...6.3261D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014SolED...6.3261D"><span>Syn-eruptive, soft-sediment deformation of dilute pyroclastic density current deposits: triggers from granular shear, dynamic <span class="hlt">pore</span> <span class="hlt">pressure</span>, ballistic impacts and shock waves</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Douillet, G. A.; Taisne, B.; Tsang-Hin-Sun, È.; Müller, S. K.; Kueppers, U.; Dingwell, D. B.</p> <p>2014-12-01</p> <p>Soft-sediment deformation produces intriguing sedimentary structures and can occur in diverse environments and from a variety of triggers. From the observation of such structures and their interpretation in terms of trigger mechanisms, valuable information can be extracted about former conditions. Here we document examples of syn-eruptive deformation in dilute pyroclastic density current deposits. Outcrops from 6 different volcanoes have been compiled in order to provide a broad perspective on the variety of structures: Ubehebe craters (USA), Tungurahua (Ecuador), Soufrière Hills (Montserrat), Laacher See (Germany), Tower Hill and Purrumbete lake (both Australia). Isolated slumps as well as sinking pseudonodules are driven by their excess weight and occur after deposition but penecontemporaneous to the eruption. Isolated, cm-scale, overturned beds with vortex forms have been interpreted to be the signature of shear instabilities occurring at the boundary of two granular media. They may represent the frozen record of granular, pseudo Kelvin-Helmholtz instabilities. Their recognition can be a diagnostic for flows with a granular basal boundary layer. The occurrence of degassing pipes together with basal intrusive dikes suggest fluidization during flow stages, and can facilitate the development of Kelvin-Helmholtz structures. The occurrence at the base of flow units of injection dikes in some outcrops compared with suction-driven local uplifts in others indicates the role of dynamic <span class="hlt">pore</span> <span class="hlt">pressure</span>. Variations of the latter are possibly related to local changes between depletive and accumulative dynamics of flows. Ballistic impacts can trigger unconventional sags producing local displacement or liquefaction. Based on the deformation depth, these can yield precise insights into depositional unit boundaries. Such impact structures may also be at the origin of some of the steep truncation planes visible at the base of the so-called "chute and pool" structures. Finally</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.ncbi.nlm.nih.gov/pubmed/28691391','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/28691391"><span><span class="hlt">Abnormal</span> <span class="hlt">Pressure</span>-Induced Photoluminescence Enhancement and Phase Decomposition in Pyrochlore La2 Sn2 O7.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Zhao, Yongsheng; Li, Nana; Xu, Cong; Li, Yan; Zhu, Hongyu; Zhu, Pinwen; Wang, Xin; Yang, Wenge</p> <p>2017-09-01</p> <p>La 2 Sn 2 O 7 is a transparent conducting oxide (TCO) material and shows a strong near-infrared fluorescent at ambient <span class="hlt">pressure</span> and room temperature. By in situ high-<span class="hlt">pressure</span> research, <span class="hlt">pressure</span>-induced visible photoluminescence (PL) above 2 GPa near 2 eV is observed. The emergence of unusual visible PL behavior is associated with the seriously trigonal lattice distortion of the SnO 6 octehedra, under which the Sn-O1-Sn exchange angle θ is decreased below 22.1 GPa, thus enhancing the PL quantum yield leading to Sn 3 P 1 → 1 S 0 photons transition. Besides, bandgap closing followed by bandgap opening and the visible PL appearing at the point of the gap reversal, which is consistent with high-<span class="hlt">pressure</span> phase decomposition, are discovered. The high-<span class="hlt">pressure</span> PL results demonstrate a well-defined <span class="hlt">pressure</span> window (7-17 GPa) with flat maximum PL yielding and sharp edges at both ends, which may provide a great calibration tool for <span class="hlt">pressure</span> sensors for operation in the deep sea or at extreme conditions. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.</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> <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/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('https://www.ncbi.nlm.nih.gov/pubmed/25534704','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/25534704"><span>Elevated blood <span class="hlt">pressure</span> in preterm-born offspring associates with a distinct antiangiogenic state and microvascular <span class="hlt">abnormalities</span> in adult life.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Lewandowski, Adam J; Davis, Esther F; Yu, Grace; Digby, Janet E; Boardman, Henry; Whitworth, Polly; Singhal, Atul; Lucas, Alan; McCormick, Kenny; Shore, Angela C; Leeson, Paul</p> <p>2015-03-01</p> <p>Preterm-born individuals have elevated blood <span class="hlt">pressure</span>. We tested the hypothesis that this associates with an enhanced antiangiogenic circulating profile and that this association is mediated by variations in capillary density. We studied 204 adults aged 25 years (range, 20-30 years), of which 102 had been followed up prospectively since very preterm birth (mean gestational age, 30.3±2.5 weeks) and 102 were born term to uncomplicated pregnancies. A panel of circulating biomarkers, including soluble endoglin and soluble fms-like tyrosine kinase-1, were compared between groups and related to perinatal history and adult cardiovascular risk. Associations with cardiovascular phenotype were studied in 90 individuals who had undergone detailed assessment of microvascular, macrovascular, and cardiac structure and function. Preterm-born individuals had elevations in soluble endoglin (5.64±1.03 versus 4.06±0.85 ng/mL; P<0.001) and soluble fms-like tyrosine kinase-1 (88.1±19.0 versus 73.0±15.3 pg/mL; P<0.001) compared with term-born individuals, proportional to elevations in resting and ambulatory blood <span class="hlt">pressure</span>, as well as degree of prematurity (P<0.05). Maternal hypertensive pregnancy disorder was associated with additional increases in soluble fms-like tyrosine kinase-1 (P=0.002). Other circulating biomarkers, including those of inflammation and endothelial activation, were not related to blood <span class="hlt">pressure</span>. There was a specific graded association between soluble endoglin and degree of functional and structural capillary rarefaction (P=0.002 and P<0.001), and in multivariable analysis, there were capillary density-mediated associations between soluble endoglin and blood <span class="hlt">pressure</span>. Preterm-born individuals exhibit an enhanced antiangiogenic state in adult life that is specifically related to elevations in blood <span class="hlt">pressure</span>. The association seems to be mediated through capillary rarefaction and is independent of other cardiovascular structural and functional differences in the</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('https://www.ncbi.nlm.nih.gov/pubmed/22822154','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/22822154"><span><span class="hlt">Abnormal</span> early diastolic intraventricular flow 'kinetic energy index' assessed by vector flow mapping in patients with elevated filling <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>Nogami, Yoshie; Ishizu, Tomoko; Atsumi, Akiko; Yamamoto, Masayoshi; Kawamura, Ryo; Seo, Yoshihiro; Aonuma, Kazutaka</p> <p>2013-03-01</p> <p>Recently developed vector flow mapping (VFM) enables evaluation of local flow dynamics without angle dependency. This study used VFM to evaluate quantitatively the index of intraventricular haemodynamic kinetic energy in patients with left ventricular (LV) diastolic dysfunction and to compare those with normal subjects. We studied 25 patients with estimated high left atrial (LA) <span class="hlt">pressure</span> (pseudonormal: PN group) and 36 normal subjects (control group). Left ventricle was divided into basal, mid, and apical segments. Intraventricular haemodynamic energy was evaluated in the dimension of speed, and it was defined as the kinetic energy index. We calculated this index and created time-energy index curves. The time interval from electrocardiogram (ECG) R wave to peak index was measured, and time differences of the peak index between basal and other segments were defined as ΔT-mid and ΔT-apex. In both groups, early diastolic peak kinetic energy index in mid and apical segments was significantly lower than that in the basal segment. Time to peak index did not differ in apex, mid, and basal segments in the control group but was significantly longer in the apex than that in the basal segment in the PN group. ΔT-mid and ΔT-apex were significantly larger in the PN group than the control group. Multiple regression analysis showed sphericity index, E/E' to be significant independent variables determining ΔT apex. Retarded apical kinetic energy fluid dynamics were detected using VFM and were closely associated with LV spherical remodelling in patients with high LA <span class="hlt">pressure</span>.</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.ncbi.nlm.nih.gov/pubmed/22032814','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/22032814"><span>Blood <span class="hlt">pressure</span> regulation and resting heart rate <span class="hlt">abnormalities</span> in adolescent girls with 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>Zachurzok-Buczynska, Agnieszka; Szydlowski, Leslaw; Gawlik, Aneta; Wilk, Krzysztof; Malecka-Tendera, Ewa</p> <p>2011-12-01</p> <p>To assess the risk of cardiovascular disease on the basis of biochemical, echocardiographic, and 24-hour blood <span class="hlt">pressure</span> (BP) monitoring parameters in adolescent girls with polycystic ovary syndrome (PCOS). Cross-sectional study. Academic and research institution. Thirty-four obese and nonobese girls with PCOS were evaluated and compared with body mass index-matched girls with regular menses. None. Androgens, gonadotropins, lipids, and fasting and oral glucose tolerance test-stimulated glucose and insulin concentrations were measured. Echocardiographic assessment and 24-hour BP monitoring were done. Compared with obese controls, obese girls with PCOS had significantly higher 24-hour mean BP, day mean BP, day diastolic BP, and diastolic BP nighttime dip (75.5 ± 4.5 mm Hg vs. 71.7 ± 3.7 mm Hg; 78.2 ± 5.0 mm Hg vs. 73.6 ± 4.0 mm Hg; 67.6 ± 4.9 mm Hg vs. 63.7 ± 3.7 mm Hg; and 20.2% ± 5.2% vs. 15.0% ± 6.6%, respectively). Obese girls with PCOS had significantly higher night heart rate than obese controls (60.4 ± 5.6 beats per minute vs. 61.7 ± 4.8 beats per minute). Left ventricle end-diastolic (4.6 ± 0.3 cm vs. 4.2 ± 0.2 cm) and end-systolic diameter (3.0 ± 0.3 cm vs. 2.7 ± 0.2 cm) were also significantly higher in nonobese girls with PCOS than in nonobese controls; however, all values were still within the accepted range of normal limits. Higher night heart rate in obese girls with PCOS and higher day BP but preserved diastolic nocturnal dip in nonobese girls with PCOS may be regarded as early cardiovascular disease risk factors. Copyright © 2011 American Society for Reproductive Medicine. Published by Elsevier Inc. All rights reserved.</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('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> <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> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/biblio/56703-meiotic-abnormalities','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/56703-meiotic-abnormalities"><span>Meiotic <span class="hlt">abnormalities</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>NONE</p> <p>1993-12-31</p> <p>Chapter 19, describes meiotic <span class="hlt">abnormalities</span>. These include nondisjunction of autosomes and sex chromosomes, genetic and environmental causes of nondisjunction, misdivision of the centromere, chromosomally <span class="hlt">abnormal</span> human sperm, male infertility, parental age, and origin of diploid gametes. 57 refs., 2 figs., 1 tab.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/16026372','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/16026372"><span>Association of angiotensin-converting enzyme DD genotype with 24-h blood <span class="hlt">pressure</span> <span class="hlt">abnormalities</span> in normoalbuminuric children and adolescents with Type 1 diabetes.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Barkai, L; Soós, A; Vámosi, I</p> <p>2005-08-01</p> <p>To assess the distribution of the insertion/deletion (I/D) polymorphism of the angiotensin-converting enzyme (ACE) gene in children and adolescents with Type 1 diabetes and to evaluate the association between ACE genotype and blood <span class="hlt">pressure</span> (BP). ACE genotypes were assessed in 124 normoalbuminuric, clinically normotensive Type 1 diabetic children and adolescents and 120 non-diabetic controls using polymerase chain reaction. Twenty-four-hour ambulatory BP monitoring was undertaken in all patients. ACE genotypes distributed in patients as follows: 34 (27%) DD, 57 (46%) ID, 33 (27%) II. The distribution was similar in the control group: DD in 28% (33), ID in 45% (54), and II in 27% (33). Patients with DD genotype had higher mean 24-h diastolic BP (73.8 +/- 6.2 vs. 70.2 +/- 5.0 and 69.7 +/- 6.3 mmHg; P = 0.005) and lower diurnal variation in BP (11.8 +/- 4.6 vs. 14.2 +/- 4.2 and 14.8 +/- 4.3%; P = 0.011) compared with ID and II groups. Four patients in the DD group proved to be non-dipper compared with one in the ID and none in the II group (P = 0.026). Twenty-four-hour diastolic blood <span class="hlt">pressure</span> was independently predictive for AER as dependent variable in the DD genotype patient group (r(2) = 0.12, P = 0.03). Children and adolescents with Type 1 diabetes do not differ from the non-diabetic population regarding the I/D polymorphism of the ACE gene. ACE gene polymorphism is associated with BP <span class="hlt">abnormalities</span> in normotensive and normoalbuminuric children and adolescents with Type 1 diabetes.</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> </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('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('https://www.healthychildren.org/English/health-issues/conditions/developmental-disabilities/Pages/Congenital-Abnormalities.aspx','NIH-MEDLINEPLUS'); return false;" href="https://www.healthychildren.org/English/health-issues/conditions/developmental-disabilities/Pages/Congenital-Abnormalities.aspx"><span>Congenital <span class="hlt">Abnormalities</span></span></a></p> <p><a target="_blank" href="http://medlineplus.gov/">MedlinePlus</a></p> <p></p> <p></p> <p>... tube defects. However, there is also a genetic influence to this type of congenital anomaly. Unknown Causes The vast majority of congenital <span class="hlt">abnormalities</span> have no known cause. This is particularly troubling for parents who plan to have more children, because there is no way to predict if ...</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/26908530','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26908530"><span>The relationship between red blood cell distribution width and blood <span class="hlt">pressure</span> <span class="hlt">abnormal</span> dipping in patients with essential hypertension: a cross-sectional study.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Su, Dan; Guo, Qi; Gao, Ya; Han, Jin; Yan, Bin; Peng, Liyuan; Song, Anqi; Zhou, Fuling; Wang, Gang</p> <p>2016-02-23</p> <p>To investigate whether red blood cell distribution width (RDW) is associated with the blood <span class="hlt">pressure</span> (BP) reverse-dipper pattern in patients with hypertension. Cross-sectional study. Single centre. Patients with essential hypertension were included in our study (n=708). The exclusion criteria included age <18 or >90 years, incomplete clinical data, night workers, diagnosis of secondary hypertension, under antihypertensive treatment, intolerance for the 24 h ambulatory BP monitoring (ABPM) and BP reading success rate <70%. Physical examination and ABPM were performed for all patients in our study. The value of RDW was measured using an automated haematology analyser. The distribution of RDW in patients with hypertension among different circadian BP pattern groups was analyzed using analysis of variance (ANOVA). Multinomial logistic regression was applied to explore the associations of RDW and other relevant variables with ABPM results. There was significantly increased RDW in reverse dippers (13.52 ± 1.05) than dippers (13.25 ± 0.85) of hypertension (p=0.012). Moreover, multinomial logistic regression analysis showed that RDW (OR 1.325, 95% CI 1.037 to 1.692, p=0.024) and diabetes mellitus (OR 2.286, 95% CI 1.380 to 3.788, p=0.001) were significantly different when comparing the reverse-dipper BP pattern with the dipper pattern. However, there was no difference of RDW between the non-dipper pattern and the reverse-dipper pattern (OR 1.036, 95% CI 0.867 to 1.238, p=0.693). In addition to this, RDW was negatively correlated with the decline rate of nocturnal systolic BP (r=-0.113; p=0.003) and diastolic BP (r=-0.101; p=0.007). Our results suggested that RDW might associate with the <span class="hlt">abnormal</span> dipper BP patterns of either reverse dipping or non-dipping homogeneously examined with 24 h ABPM. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/</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.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/scitech">SciTech Connect</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/19324237','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/19324237"><span><span class="hlt">Abnormal</span> placentation.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Bauer, Samuel T; Bonanno, Clarissa</p> <p>2009-04-01</p> <p><span class="hlt">Abnormal</span> placentation poses a diagnostic and treatment challenge for all providers caring for pregnant women. As one of the leading causes of postpartum hemorrhage, <span class="hlt">abnormal</span> placentation involves the attachment of placental villi directly to the myometrium with potentially deeper invasion into the uterine wall or surrounding organs. Surgical procedures that disrupt the integrity of uterus, including cesarean section, dilatation and curettage, and myomectomy, have been implicated as key risk factors for placenta accreta. The diagnosis is typically made by gray-scale ultrasound and confirmed with magnetic resonance imaging, which may better delineate the extent of placental invasion. It is critical to make the diagnosis before delivery because preoperative planning can significantly decrease blood loss and avoid substantial morbidity associated with placenta accreta. Aggressive management of hemorrhage through the use of uterotonics, fluid resuscitation, blood products, planned hysterectomy, and surgical hemostatic agents can be life-saving for these patients. Conservative management, including the use of uterine and placental preservation and subsequent methotrexate therapy or pelvic artery embolization, may be considered when a focal accreta is suspected; however, surgical management remains the current standard of care.</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('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('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/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://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('http://adsabs.harvard.edu/abs/2017SPIE10399E..0MV','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017SPIE10399E..0MV"><span>Predicting silicon <span class="hlt">pore</span> optics</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Vacanti, Giuseppe; Barriére, Nicolas; Bavdaz, Marcos; Chatbi, Abdelhakim; Collon, Maximilien; Dekker, Danielle; Girou, David; Günther, Ramses; van der Hoeven, Roy; Landgraf, Boris; Sforzini, Jessica; Vervest, Mark; Wille, Eric</p> <p>2017-09-01</p> <p>Continuing improvement of Silicon <span class="hlt">Pore</span> Optics (SPO) calls for regular extension and validation of the tools used to model and predict their X-ray performance. In this paper we present an updated geometrical model for the SPO optics and describe how we make use of the surface metrology collected during each of the SPO manufacturing runs. The new geometrical model affords the user a finer degree of control on the mechanical details of the SPO stacks, while a standard interface has been developed to make use of any type of metrology that can return changes in the local surface normal of the reflecting surfaces. Comparisons between the predicted and actual performance of samples optics will be shown and discussed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017SPIE10399E..0NV','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017SPIE10399E..0NV"><span>Measuring silicon <span class="hlt">pore</span> optics</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Vacanti, Giuseppe; Barrière, Nicolas; Bavdaz, Marcos; Chatbi, Abdelhakim; Collon, Maximilien; Dekker, Daniëlle; Girou, David; Günther, Ramses; van der Hoeven, Roy; Krumrey, Michael; Landgraf, Boris; Müller, Peter; Schreiber, Swenja; Vervest, Mark; Wille, Eric</p> <p>2017-09-01</p> <p>While predictions based on the metrology (local slope errors and detailed geometrical details) play an essential role in controlling the development of the manufacturing processes, X-ray characterization remains the ultimate indication of the actual performance of Silicon <span class="hlt">Pore</span> Optics (SPO). For this reason SPO stacks and mirror modules are routinely characterized at PTB's X-ray Pencil Beam Facility at BESSY II. Obtaining standard X-ray results quickly, right after the production of X-ray optics is essential to making sure that X-ray results can inform decisions taken in the lab. We describe the data analysis pipeline in operations at cosine, and how it allows us to go from stack production to full X-ray characterization in 24 hours.</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('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.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.acog.org/~/media/For%20Patients/faq095.pdf?dmc=1&ts=20130508T0825225315','NIH-MEDLINEPLUS'); return false;" href="https://www.acog.org/~/media/For%20Patients/faq095.pdf?dmc=1&ts=20130508T0825225315"><span><span class="hlt">Abnormal</span> Uterine Bleeding FAQ</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 • What is a normal menstrual cycle? • When is bleeding <span class="hlt">abnormal</span>? • At what ages is ... <span class="hlt">abnormal</span> bleeding? •Glossary What is a normal menstrual cycle? The normal length of the menstrual cycle is ...</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://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('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('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.ncbi.nlm.nih.gov/pubmed/15518624','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/15518624"><span>Development of exercise-induced arm-leg blood <span class="hlt">pressure</span> gradient and <span class="hlt">abnormal</span> arterial compliance in patients with repaired coarctation of the aorta.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Markham, Larry W; Knecht, Sandra K; Daniels, Stephen R; Mays, Wayne A; Khoury, Philip R; Knilans, Timothy K</p> <p>2004-11-01</p> <p>Often, the lack of systemic arterial hypertension and the lack of a resting arm-leg blood <span class="hlt">pressure</span> gradient are used to assess the adequacy of the anatomic result after intervention for coarctation of the aorta (CoA). Some patients with no arm-leg gradient at rest may develop a gradient with exercise, leading caregivers to question the success of the repair. It is not clear what the prevalence is of patients who have undergone a successful intervention for CoA and have no arm-leg gradient at rest but develop a significant gradient with exercise and which factors may predict the development of an arm-leg gradient with exercise. This study evaluates the prevalence and predictors of an exercise-induced arm-leg gradient in subjects who have undergone an apparently successful intervention for CoA.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/25376639','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/25376639"><span>Racial differences in <span class="hlt">abnormal</span> ambulatory blood <span class="hlt">pressure</span> monitoring measures: Results from the Coronary Artery Risk Development in Young Adults (CARDIA) study.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Muntner, Paul; Lewis, Cora E; Diaz, Keith M; Carson, April P; Kim, Yongin; Calhoun, David; Yano, Yuichiro; Viera, Anthony J; Shimbo, Daichi</p> <p>2015-05-01</p> <p>Several ambulatory blood <span class="hlt">pressure</span> monitoring (ABPM) measures have been associated with increased cardiovascular disease risk independent of clinic blood <span class="hlt">pressure</span> (BP). African Americans have higher clinic BP compared with Whites but few data are available on racial differences in ABPM measures. We compared ABPM measures between African American (n = 178) and White (n = 103) participants at the Year 5 Coronary Artery Risk Development in Young Adults study visit. BP was measured during a study visit and the second and third measurements were averaged. ABPM was conducted over the following 24 hours. Mean ± SD age of participants was 29.8 ± 3.8 years and 30.8 ± 3.5 years for African Americans and Whites, respectively. Mean daytime systolic BP (SBP) was 3.90 (SD 1.18) mm Hg higher among African Americans compared with Whites (P < 0.001) after age-gender adjustment and 1.71 (SD 1.03) mm Hg higher after multivariable adjustment including mean clinic SBP (P = 0.10). After multivariable adjustment including mean clinic SBP, nighttime SBP was 4.83 (SD 1.11) mm Hg higher among African Americans compared with Whites (P < 0.001). After multivariable adjustment, the African Americans were more likely than Whites to have nocturnal hypertension (prevalence ratio: 2.44, 95% CI: 0.99-6.05) and nondipping (prevalence ratio: 2.50, 95% CI: 1.39-4.48). The prevalence of masked hypertension among African Americans and Whites was 4.4% and 2.1%, respectively, (P = 0.49) and white coat hypertension was 3.3% and 3.9%, respectively (P = 0.99). Twenty-four hour BP variability on ABPM was higher among African Americans compared with Whites. These data suggest racial differences in several ABPM measures exist. © American Journal of Hypertension, Ltd 2014. All rights reserved. For Permissions, please email: journals.permissions@oup.com.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/servlets/purl/871686','DOE-PATENT-XML'); return false;" href="https://www.osti.gov/servlets/purl/871686"><span>Triggered <span class="hlt">pore</span>-forming agents</span></a></p> <p><a target="_blank" href="http://www.osti.gov/doepatents">DOEpatents</a></p> <p>Bayley, Hagan; Walker, Barbara J.; Chang, Chung-yu; Niblack, Brett; Panchal, Rekha</p> <p>1998-01-01</p> <p>An inactive <span class="hlt">pore</span>-forming agent which is activated to lytic function by a condition such as pH, light, heat, reducing potential, or metal ion concentration, or substance such as a protease, at the surface of a cell.</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/scitech">SciTech Connect</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/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('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/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/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('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/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://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('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://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/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> </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('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://medlineplus.gov/ency/article/003139.htm','NIH-MEDLINEPLUS'); return false;" href="https://medlineplus.gov/ency/article/003139.htm"><span>Urine - <span class="hlt">abnormal</span> color</span></a></p> <p><a target="_blank" href="http://medlineplus.gov/">MedlinePlus</a></p> <p></p> <p></p> <p>... medlineplus.gov/ency/article/003139.htm Urine - <span class="hlt">abnormal</span> color To use the sharing features on this page, please enable JavaScript. The usual color of urine is straw-yellow. <span class="hlt">Abnormally</span> colored urine ...</p> </li> <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/scitech">SciTech Connect</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('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/scitech">SciTech Connect</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/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('https://www.osti.gov/biblio/672564','DOE-PATENT-XML'); return false;" href="https://www.osti.gov/biblio/672564"><span>Triggered <span class="hlt">pore</span>-forming agents</span></a></p> <p><a target="_blank" href="http://www.osti.gov/doepatents">DOEpatents</a></p> <p>Bayley, H.; Walker, B.J.; Chang, C.Y.; Niblack, B.; Panchal, R.</p> <p>1998-07-07</p> <p>An inactive <span class="hlt">pore</span>-forming agent is revealed which is activated to lytic function by a condition such as pH, light, heat, reducing potential, or metal ion concentration, or substance such as a protease, at the surface of a cell. 30 figs.</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('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('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/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('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/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('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://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://medlineplus.gov/ency/article/003064.htm','NIH-MEDLINEPLUS'); return false;" href="https://medlineplus.gov/ency/article/003064.htm"><span>Tooth - <span class="hlt">abnormal</span> shape</span></a></p> <p><a target="_blank" href="http://medlineplus.gov/">MedlinePlus</a></p> <p></p> <p></p> <p>Hutchinson incisors; <span class="hlt">Abnormal</span> tooth shape; Peg teeth; Mulberry teeth; Conical teeth ... The appearance of normal teeth varies, especially the molars. ... conditions. Specific diseases can affect tooth shape, tooth ...</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://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://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('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> </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/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('http://adsabs.harvard.edu/abs/2014SPIE.9144E..2HW','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014SPIE.9144E..2HW"><span>Qualification of silicon <span class="hlt">pore</span> optics</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Wille, Eric; Bavdaz, Marcos; Fransen, Sebastiaan; Collon, Maximilien; Ackermann, Marcelo; Guenther, Ramses; Chatbi, Abdelhakim; Vacanti, Giuseppe; Vervest, Mark; van Baren, Coen; Haneveld, Jeroen; Riekerink, Mark Olde; Koelewijn, Arenda; Kampf, Dirk; Zuknik, Karl-Heinz; Reutlinger, Arnd</p> <p>2014-07-01</p> <p>Silicon <span class="hlt">Pore</span> Optics (SPO) are the enabling technology for ESA's second large class mission in the Cosmic Vision programme. As for every space hardware, a critical qualification process is required to verify the suitability of the SPO mirror modules surviving the launch loads and maintaining their performance in the space environment. We present recent design modifications to further strengthen the mounting system (brackets and dowel pins) against mechanical loads. The progress of a formal qualification test campaign with the new mirror module design is shown. We discuss mechanical and thermal limitations of the SPO technology and provide recommendations for the mission design of the next X-ray Space Observatory.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=2169373','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=2169373"><span>The Yeast Nuclear <span class="hlt">Pore</span> Complex</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Rout, Michael P.; Aitchison, John D.; Suprapto, Adisetyantari; Hjertaas, Kelly; Zhao, Yingming; Chait, Brian T.</p> <p>2000-01-01</p> <p>An understanding of how the nuclear <span class="hlt">pore</span> complex (NPC) mediates nucleocytoplasmic exchange requires a comprehensive inventory of the molecular components of the NPC and a knowledge of how each component contributes to the overall structure of this large molecular translocation machine. Therefore, we have taken a comprehensive approach to classify all components of the yeast NPC (nucleoporins). This involved identifying all the proteins present in a highly enriched NPC fraction, determining which of these proteins were nucleoporins, and localizing each nucleoporin within the NPC. Using these data, we present a map of the molecular architecture of the yeast NPC and provide evidence for a Brownian affinity gating mechanism for nucleocytoplasmic transport. PMID:10684247</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/scitech">SciTech Connect</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('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/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('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('https://eric.ed.gov/?q=abnormal+AND+psychology&pg=4&id=EJ469650','ERIC'); return false;" href="https://eric.ed.gov/?q=abnormal+AND+psychology&pg=4&id=EJ469650"><span>"Jeopardy" in <span class="hlt">Abnormal</span> Psychology.</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>Keutzer, Carolin S.</p> <p>1993-01-01</p> <p>Describes the use of the board game, Jeopardy, in a college level <span class="hlt">abnormal</span> psychology course. Finds increased student interaction and improved application of information. Reports generally favorable student evaluation of the technique. (CFR)</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('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/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> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/biblio/7086345','DOE-PATENT-XML'); return false;" href="https://www.osti.gov/biblio/7086345"><span>Open-<span class="hlt">pore</span> polyurethane product</span></a></p> <p><a target="_blank" href="http://www.osti.gov/doepatents">DOEpatents</a></p> <p>Jefferson, R.T.; Salyer, I.O.</p> <p>1974-02-17</p> <p>The method is described of producing an open-<span class="hlt">pore</span> polyurethane foam having a porosity of at least 50% and a density of 0.1 to 0.5 g per cu cm, and which consists of coherent spherical particles of less than 10 mu diam separated by interconnected interstices. It is useful as a filter and oil absorbent. The product is admirably adapted to scavenging of crude oil from the surface of seawater by preferential wicking. The oil-soaked product may then be compressed to recover the oil or burned for disposal. The crosslinked polyurethane structures are remarkably solvent and heat-resistance as compared with known thermoplastic structures. Because of their relative inertness, they are useful filters for gasoline and other hydrocarbon compounds. (7 claims)</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('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('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/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('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/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('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> </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('https://www.ncbi.nlm.nih.gov/pubmed/21688762','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/21688762"><span>Lenticular <span class="hlt">abnormalities</span> in children.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Khokhar, Sudarshan; Agarwal, Tushar; Kumar, Gaurav; Kushmesh, Rakhi; Tejwani, Lalit Kumar</p> <p>2012-01-01</p> <p>To study the lenticular problems in children presenting at an apex institute. Retrospective analysis of records (< 14 years) of new lens clinic cases was done. Of 1,047 children, 687 were males. Mean age at presentation was 6.35 ± 4.13 years. Developmental cataract was seen in 45.6% and posttraumatic cataract in 29.7% of patients. Other <span class="hlt">abnormalities</span> were cataract with retinal detachment, persistent hyperplastic primary vitreous, subluxated lens, micro/spherophakia, cataract secondary to uveitis, intraocular lens complications, cataract with choroidal coloboma, and visual axis opacification. Developmental and posttraumatic cataracts were the most common <span class="hlt">abnormalities</span>. Delayed presentation is of concern. Copyright 2012, SLACK Incorporated.</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.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('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('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/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://www.ncbi.nlm.nih.gov/pubmed/7675220','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/7675220"><span>Neurologic <span class="hlt">abnormalities</span> in murderers.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Blake, P Y; Pincus, J H; Buckner, C</p> <p>1995-09-01</p> <p>Thirty-one individuals awaiting trial or sentencing for murder or undergoing an appeal process requested a neurologic examination through legal counsel. We attempted in each instance to obtain EEG, MRI or CT, and neuropsychological testing. Neurologic examination revealed evidence of "frontal" dysfunction in 20 (64.5%). There were symptoms or some other evidence of temporal lobe <span class="hlt">abnormality</span> in nine (29%). We made a specific neurologic diagnosis in 20 individuals (64.5%), including borderline or full mental retardation (9) and cerebral palsy (2), among others. Neuropsychological testing revealed <span class="hlt">abnormalities</span> in all subjects tested. There were EEG <span class="hlt">abnormalities</span> in eight of the 20 subjects tested, consisting mainly of bilateral sharp waves with slowing. There were MRI or CT <span class="hlt">abnormalities</span> in nine of the 19 subjects tested, consisting primarily of atrophy and white matter changes. Psychiatric diagnoses included paranoid schizophrenia (8), dissociative disorder (4), and depression (9). Virtually all subjects had paranoid ideas and misunderstood social situations. There was a documented history of profound, protracted physical abuse in 26 (83.8%) and of sexual abuse in 10 (32.3%). It is likely that prolonged, severe physical abuse, paranoia, and neurologic brain dysfunction interact to form the matrix of violent behavior.</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> <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('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/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('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('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('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('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://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/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('https://www.ncbi.nlm.nih.gov/pubmed/24055170','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/24055170"><span><span class="hlt">Abnormality</span>, rationality, and sanity.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Hertwig, Ralph; Volz, Kirsten G</p> <p>2013-11-01</p> <p>A growing body of studies suggests that neurological and mental <span class="hlt">abnormalities</span> foster conformity to norms of rationality that are widely endorsed in economics and psychology, whereas normality stands in the way of rationality thus defined. Here, we outline the main findings of these studies, discuss their implications for experimental design, and consider how 'sane' some benchmarks of rationality really are. Copyright © 2013 Elsevier Ltd. 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_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('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('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://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('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/scitech">SciTech Connect</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('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('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/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('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://hdl.handle.net/2060/19660000321','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19660000321"><span>Valve seat <span class="hlt">pores</span> sealed with thermosetting monomer</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Olmore, A. B.</p> <p>1966-01-01</p> <p>Hard anodic coating provides a smooth wear resistant value seating surface on a cast aluminum alloy valve body. Vacuum impregnation with a thermosetting monomer, diallyl phthalate, seals the <span class="hlt">pores</span> on the coating to prevent galvanic corrosion.</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/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/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('https://www.ncbi.nlm.nih.gov/pubmed/28605821','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/28605821"><span><span class="hlt">Abnormal</span> Uterine Bleeding.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Benetti-Pinto, Cristina Laguna; Rosa-E-Silva, Ana Carolina Japur de Sá; Yela, Daniela Angerame; Soares Júnior, José Maria</p> <p>2017-07-01</p> <p><span class="hlt">Abnormal</span> uterine bleeding is a frequent condition in Gynecology. It may impact physical, emotional sexual and professional aspects of the lives of women, impairing their quality of life. In cases of acute and severe bleeding, women may need urgent treatment with volumetric replacement and prescription of hemostatic substances. In some specific cases with more intense and prolonged bleeding, surgical treatment may be necessary. The objective of this chapter is to describe the main evidence on the treatment of women with <span class="hlt">abnormal</span> uterine bleeding, both acute and chronic. Didactically, the treatment options were based on the current International Federation of Gynecology and Obstetrics (FIGO) classification system (PALM-COEIN). The etiologies of PALM-COEIN are: uterine Polyp (P), Adenomyosis (A), Leiomyoma (L), precursor and Malignant lesions of the uterine body (M), Coagulopathies (C), Ovulatory dysfunction (O), Endometrial dysfunction (E), Iatrogenic (I), and Not yet classified (N). The articles were selected according to the recommendation grades of the PubMed, Cochrane and Embase databases, and those in which the main objective was the reduction of uterine menstrual bleeding were included. Only studies written in English were included. All editorial or complete papers that were not consistent with <span class="hlt">abnormal</span> uterine bleeding, or studies in animal models, were excluded. The main objective of the treatment is the reduction of menstrual flow and morbidity and the improvement of quality of life. It is important to emphasize that the treatment in the acute phase aims to hemodynamically stabilize the patient and stop excessive bleeding, while the treatment in the chronic phase is based on correcting menstrual dysfunction according to its etiology and clinical manifestations. The treatment may be surgical or pharmacological, and the latter is based mainly on hormonal therapy, anti-inflammatory drugs and antifibrinolytics. Thieme Revinter Publicações Ltda Rio de Janeiro</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011MsT..........2P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011MsT..........2P"><span>Data based <span class="hlt">abnormality</span> detection</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Purwar, Yashasvi</p> <p></p> <p>Data based <span class="hlt">abnormality</span> detection is a growing research field focussed on extracting information from feature rich data. They are considered to be non-intrusive and non-destructive in nature which gives them a clear advantage over conventional methods. In this study, we explore different streams of data based anomalies detection. We propose extension and revisions to existing valve stiction detection algorithm supported with industrial case study. We also explored the area of image analysis and proposed a complete solution for Malaria diagnosis. The proposed method is tested over images provided by pathology laboratory at Alberta Health Service. We also address the robustness and practicality of the solution proposed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/25903257','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/25903257"><span>Morphological <span class="hlt">abnormalities</span> in elasmobranchs.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Moore, A B M</p> <p>2015-08-01</p> <p>A total of 10 <span class="hlt">abnormal</span> free-swimming (i.e., post-birth) elasmobranchs are reported from The (Persian-Arabian) Gulf, encompassing five species and including deformed heads, snouts, caudal fins and claspers. The complete absence of pelvic fins in a milk shark Rhizoprionodon acutus may be the first record in any elasmobranch. Possible causes, including the extreme environmental conditions and the high level of anthropogenic pollution particular to The Gulf, are briefly discussed. © 2015 The Fisheries Society of the British Isles.</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://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('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.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> </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.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('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.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('http://adsabs.harvard.edu/abs/2010AGUFMEP31E..01B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010AGUFMEP31E..01B"><span>Interactions between bedforms, turbulence and <span class="hlt">pore</span> flow</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Blois, G.; Best, J.; Sambrook Smith, G.; Hardy, R. J.; Lead, J.</p> <p>2010-12-01</p> <p>A widespread occurrence of flow-form interaction in rivers is represented by subaqueous bedforms such as dunes. Many models have been proposed to explain how bedform generation and evolution are driven by turbulent flow structures that control the incipient motion of cohesionless sediments and later bedform development. However, most of these models have assumed such bedforms to be migrating over an impermeable bed, and that any surface-subsurface flow interaction is negligible. However, for some gravel-bed rivers the porosity can be high, up to 43%, which may result in significant flow both through the permeable bed (hyporheic flow) and across the surface-subsurface interface. The mass and momentum exchange occurring at the interface may have a strong impact on the structure of turbulent flow in the near-bed region. In the case of a dune, its topography induces a local <span class="hlt">pressure</span> gradient that enhances flow across the interface. This results in a flow structure that may be radically different from that commonly proposed by past work. This paper presents results from a simplified laboratory model akin to a fine-grained bedform generated on top of a coarser sediment bed. Particle imaging velocimetry (PIV) measurements were conducted in order to characterise flow both over and underneath an idealised 2-dimensional dune (0.41 m long, 0.056 m high and having a leeside angle of 27°) overlaying a packed bed of uniform size spheres (D = 0.04 m diameter). Experiments were conducted in free surface flow conditions (Froude number = 0.1; Reynolds number = 25,000) for one bedform height: flow depth ratio (0.31). The flow above the dune was measured using a standard PIV technique while a novel endoscopic PIV (EPIV) system allowed collection of flow data within the <span class="hlt">pore</span> spaces beneath the dune. The results show that topographically-induced subsurface flow significantly modifies the structure of flow in the leeside of the dune, resulting in a flow field that is radically different</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('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('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('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.ncbi.nlm.nih.gov/pubmed/27347227','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/27347227"><span>Ictal Cardiac Ryhthym <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>Ali, Rushna</p> <p>2016-01-01</p> <p>Cardiac rhythm <span class="hlt">abnormalities</span> in the context of epilepsy are a well-known phenomenon. However, they are under-recognized and often missed. The pathophysiology of these events is unclear. Bradycardia and asystole are preceded by seizure onset suggesting ictal propagation into the cortex impacting cardiac autonomic function, and the insula and amygdala being possible culprits. Sudden unexpected death in epilepsy (SUDEP) refers to the unanticipated death of a patient with epilepsy not related to status epilepticus, trauma, drowning, or suicide. Frequent refractory generalized tonic-clonic seizures, anti-epileptic polytherapy, and prolonged duration of epilepsy are some of the commonly identified risk factors for SUDEP. However, the most consistent risk factor out of these is an increased frequency of generalized tonic-clonic seizures (GTC). Prevention of SUDEP is extremely important in patients with chronic, generalized epilepsy. Since increased frequency of GTCS is the most consistently reported risk factor for SUDEP, effective seizure control is the most important preventive strategy.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/24868489','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/24868489"><span>Esophageal motility <span class="hlt">abnormalities</span> in gastroesophageal reflux disease.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Martinucci, Irene; de Bortoli, Nicola; Giacchino, Maria; Bodini, Giorgia; Marabotto, Elisa; Marchi, Santino; Savarino, Vincenzo; Savarino, Edoardo</p> <p>2014-05-06</p> <p>Esophageal motility <span class="hlt">abnormalities</span> are among the main factors implicated in the pathogenesis of gastroesophageal reflux disease. The recent introduction in clinical and research practice of novel esophageal testing has markedly improved our understanding of the mechanisms contributing to the development of gastroesophageal reflux disease, allowing a better management of patients with this disorder. In this context, the present article intends to provide an overview of the current literature about esophageal motility dysfunctions in patients with gastroesophageal reflux disease. Esophageal manometry, by recording intraluminal <span class="hlt">pressure</span>, represents the gold standard to diagnose esophageal motility <span class="hlt">abnormalities</span>. In particular, using novel techniques, such as high resolution manometry with or without concurrent intraluminal impedance monitoring, transient lower esophageal sphincter (LES) relaxations, hypotensive LES, ineffective esophageal peristalsis and bolus transit <span class="hlt">abnormalities</span> have been better defined and strongly implicated in gastroesophageal reflux disease development. Overall, recent findings suggest that esophageal motility <span class="hlt">abnormalities</span> are increasingly prevalent with increasing severity of reflux disease, from non-erosive reflux disease to erosive reflux disease and Barrett's esophagus. Characterizing esophageal dysmotility among different subgroups of patients with reflux disease may represent a fundamental approach to properly diagnose these patients and, thus, to set up the best therapeutic management. Currently, surgery represents the only reliable way to restore the esophagogastric junction integrity and to reduce transient LES relaxations that are considered to be the predominant mechanism by which gastric contents can enter the esophagus. On that ground, more in depth future studies assessing the pathogenetic role of dysmotility in patients with reflux disease are warranted.</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('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/21386663','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/21386663"><span>Unplugging the callose plug from sieve <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>Xie, Bo; Hong, Zonglie</p> <p>2011-04-01</p> <p>The presence of callose in sieve plates has been known for a long time, but how this polysaccharide plug is synthesized has remained unsolved. Two independent laboratories have recently reported the identification of callose synthase 7 (CalS7), also known as glucan synthase-like 7 (GSL7), as the enzyme responsible for callose deposition in sieve plates. Mutant plants defective in this enzyme failed to synthesize callose in developing sieve plates during phloem formation and were unable to accumulate callose in sieve <span class="hlt">pores</span> in response to stress treatments. The mutant plants developed less open <span class="hlt">pores</span> per sieve plate and the <span class="hlt">pores</span> were smaller in diameter. As a result, phloem conductivity was reduced significantly and the mutant plants were shorter and set fewer seeds.</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.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3142375','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3142375"><span>Unplugging the callose plug from sieve <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>Xie, Bo</p> <p>2011-01-01</p> <p>The presence of callose in sieve plates has been known for a long time, but how this polysaccharide plug is synthesized has remained unsolved. Two independent laboratories have recently reported the identification of callose synthase 7 (CalS7), also known as glucan synthase-like 7 (GSL7), as the enzyme responsible for callose deposition in sieve plates. Mutant plants defective in this enzyme failed to synthesize callose in developing sieve plates during phloem formation and were unable to accumulate callose in sieve <span class="hlt">pores</span> in response to stress treatments. The mutant plants developed less open <span class="hlt">pores</span> per sieve plate and the <span class="hlt">pores</span> were smaller in diameter. As a result, phloem conductivity was reduced significantly and the mutant plants were shorter and set fewer seeds. PMID:21386663</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('https://www.ncbi.nlm.nih.gov/pubmed/28676424','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/28676424"><span>Nuclear <span class="hlt">pore</span> complex tethers to the cytoskeleton.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Goldberg, Martin W</p> <p>2017-08-01</p> <p>The nuclear envelope is tethered to the cytoskeleton. The best known attachments of all elements of the cytoskeleton are via the so-called LINC complex. However, the nuclear <span class="hlt">pore</span> complexes, which mediate the transport of soluble and membrane bound molecules, are also linked to the microtubule network, primarily via motor proteins (dynein and kinesins) which are linked, most importantly, to the cytoplasmic filament protein of the nuclear <span class="hlt">pore</span> complex, Nup358, by the adaptor BicD2. The evidence for such linkages and possible roles in nuclear migration, cell cycle control, nuclear transport and cell architecture are discussed. Copyright © 2017. Published by Elsevier Ltd.</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/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('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> </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('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/scitech">SciTech Connect</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('https://www.ncbi.nlm.nih.gov/pubmed/28910998','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/28910998"><span><span class="hlt">Abnormal</span> uterine bleeding.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Cheong, Ying; Cameron, Iain T; Critchley, Hilary O D</p> <p>2017-09-01</p> <p>It is not uncommon for a woman to suffer from <span class="hlt">abnormal</span> uterine bleeding (AUB) or heavy menstrual bleeding (HMB) at some point during her lifetime. Once pathology is excluded, in practice, management needs to be individualised, taking into account the improvement of the woman's symptoms and quality of life. Peer-reviewed journals, governmental and professional society publications. There is now agreement on a structured, universal approach to the diagnosis of AUB, with the aide memoirs PALM (polyps, adenomyosis, leiomyoma, malignancy) and COEIN (coagulopathies, ovulatory dysfunction, endometrial, iatrogenic, not otherwise classified). Once malignancy and significant pelvic pathology have been ruled out, medical treatment is an effective first-line therapeutic option, with surgery, including endometrial ablation and hysterectomy, offered when medical management has failed to resolve symptoms and fertility is no longer desired. There remains controversy around the management of the types and subtypes of adenomyosis and leiomyoma, and understanding their impact on clinical reproductive outcomes. Standardised assessment tools for measuring outcomes of AUB are being developed. Novel diagnostic and monitoring tools should be developed to help stratify treatment for women with AUB, particularly relating to 'unclassified' and 'endometrial' causes. © The Author 2017. Published by Oxford University Press. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/261653','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/261653"><span>Communication and <span class="hlt">abnormal</span> behaviour.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Crown, S</p> <p>1979-01-01</p> <p>In this paper the similarities between normal and <span class="hlt">abnormal</span> behaviour are emphasized and selected aspects of communication, normal and aberrant, between persons are explored. Communication in a social system may be verbal or non-verbal: one person's actions cause a response in another person. This response may be cognitive, behavioural or physiological. Communication may be approached through the individual, the social situation or social interaction. Psychoanalysis approaches the individual in terms of the coded communications of psychoneurotic symptoms or psychotic behaviour; the humanist-existential approach is concerned more with emotional expression. Both approaches emphasize the development of individual identity. The interaction between persons and their social background is stressed. Relevant are sociological concepts such as illness behaviour, stigma, labelling, institutionalization and compliance. Two approaches to social interactions are considered: the gamesplaying metaphor, e.g. back pain as a psychosocial manipulation--the 'pain game'; and the 'spiral of reciprocal perspectives' which emphasizes the interactional complexities of social perceptions. Communicatory aspects of psychological treatments are noted: learning a particular metaphor such as 'resolution' of the problem (psychotherapy), learning more 'rewarding' behaviour (learning theory) or learning authenticity or self-actualization (humanist-existential).</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/7410733','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/7410733"><span>Autoshaping of <span class="hlt">abnormal</span> children.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Deckner, C W; Wilcox, L M; Maisto, S A; Blanton, R L</p> <p>1980-09-01</p> <p>Three experimentally naive <span class="hlt">abnormal</span> children were exposed to a terminal operant contingency, i.e., reinforcement was delivered only if the children pressed a panel during intervals when it was lighted. Despite the absence of both successive approximation and manual shaping, it was found that each child began to respond discriminatively within a small number of trials. These data replicated previous animal studies concerned with the phenomena of autoshaping and signal-controlled responding. It was also found, however, that one type of autoshaping, the classical conditioning procedure, had a powerful suppressive effect on the discriminative responding. An experimental analysis that consisted procedure, had a powerful suppressive effect on discriminative responding. An experimental analysis that consisted of intrasubject reversal an multiple baseline designs established the internal validity of the findings. The finding of rapid acquisition of signal-controlled responding obtained with the initial procedure is suggessted to have practical significance. The disruptive effects of the classical form of autoshaping are discussed in terms of negative behavioral contrast.</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('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('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.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/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('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=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('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('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/scitech">SciTech Connect</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('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://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/scitech">SciTech Connect</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/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/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('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/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> </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('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/scitech">SciTech Connect</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/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/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/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> <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> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3442237','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3442237"><span><span class="hlt">Pores</span> and Void in Asclepiades’ Physical Theory</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Leith, David</p> <p>2012-01-01</p> <p>This paper examines a fundamental, though relatively understudied, aspect of the physical theory of the physician Asclepiades of Bithynia, namely his doctrine of <span class="hlt">pores</span>. My principal thesis is that this doctrine is dependent on a conception of void taken directly from Epicurean physics. The paper falls into two parts: the first half addresses the evidence for the presence of void in Asclepiades’ theory, and concludes that his conception of void was basically that of Epicurus; the second half focuses on the precise nature of Asclepiadean <span class="hlt">pores</span>, and seeks to show that they represent void interstices between the primary particles of matter which are the constituents of the human body, and are thus exactly analogous to the void interstices between atoms within solid objects in Epicurus’ theory. PMID:22984299</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/28497794','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/28497794"><span><span class="hlt">Pore</span> configuration landscape of granular crystallization.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Saadatfar, M; Takeuchi, H; Robins, V; Francois, N; Hiraoka, Y</p> <p>2017-05-12</p> <p>Uncovering grain-scale mechanisms that underlie the disorder-order transition in assemblies of dissipative, athermal particles is a fundamental problem with technological relevance. To date, the study of granular crystallization has mainly focussed on the symmetry of crystalline patterns while their emergence and growth from irregular clusters of grains remains largely unexplored. Here crystallization of three-dimensional packings of frictional spheres is studied at the grain-scale using X-ray tomography and persistent homology. The latter produces a map of the topological configurations of grains within static partially crystallized packings. Using numerical simulations, we show that similar maps are measured dynamically during the melting of a perfect crystal. This map encodes new information on the formation process of tetrahedral and octahedral <span class="hlt">pores</span>, the building blocks of perfect crystals. Four key formation mechanisms of these <span class="hlt">pores</span> reproduce the main changes of the map during crystallization and provide continuous deformation pathways representative of the crystallization dynamics.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5437301','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5437301"><span><span class="hlt">Pore</span> configuration landscape of granular crystallization</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Saadatfar, M.; Takeuchi, H.; Robins, V.; Francois, N.; Hiraoka, Y.</p> <p>2017-01-01</p> <p>Uncovering grain-scale mechanisms that underlie the disorder–order transition in assemblies of dissipative, athermal particles is a fundamental problem with technological relevance. To date, the study of granular crystallization has mainly focussed on the symmetry of crystalline patterns while their emergence and growth from irregular clusters of grains remains largely unexplored. Here crystallization of three-dimensional packings of frictional spheres is studied at the grain-scale using X-ray tomography and persistent homology. The latter produces a map of the topological configurations of grains within static partially crystallized packings. Using numerical simulations, we show that similar maps are measured dynamically during the melting of a perfect crystal. This map encodes new information on the formation process of tetrahedral and octahedral <span class="hlt">pores</span>, the building blocks of perfect crystals. Four key formation mechanisms of these <span class="hlt">pores</span> reproduce the main changes of the map during crystallization and provide continuous deformation pathways representative of the crystallization dynamics. PMID:28497794</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017NatCo...815082S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017NatCo...815082S"><span><span class="hlt">Pore</span> configuration landscape of granular crystallization</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Saadatfar, M.; Takeuchi, H.; Robins, V.; Francois, N.; Hiraoka, Y.</p> <p>2017-05-01</p> <p>Uncovering grain-scale mechanisms that underlie the disorder-order transition in assemblies of dissipative, athermal particles is a fundamental problem with technological relevance. To date, the study of granular crystallization has mainly focussed on the symmetry of crystalline patterns while their emergence and growth from irregular clusters of grains remains largely unexplored. Here crystallization of three-dimensional packings of frictional spheres is studied at the grain-scale using X-ray tomography and persistent homology. The latter produces a map of the topological configurations of grains within static partially crystallized packings. Using numerical simulations, we show that similar maps are measured dynamically during the melting of a perfect crystal. This map encodes new information on the formation process of tetrahedral and octahedral <span class="hlt">pores</span>, the building blocks of perfect crystals. Four key formation mechanisms of these <span class="hlt">pores</span> reproduce the main changes of the map during crystallization and provide continuous deformation pathways representative of the crystallization dynamics.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017EGUGA..19.2769A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017EGUGA..19.2769A"><span>A fast Laplace solver approach to <span class="hlt">pore</span> scale permeability</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Arns, Christoph; Adler, Pierre</p> <p>2017-04-01</p> <p>The permeability of a porous medium can be derived by solving the Stokes equations in the <span class="hlt">pore</span> space with no slip at the walls. The resulting velocity averaged over the <span class="hlt">pore</span> volume yields the permeability KS by application of the Darcy law. The Stokes equations can be solved by a number of different techniques such as finite differences, finite volume, Lattice Boltzmann, but whatever the technique it remains a heavy task since there are four unknowns at each node (the three velocity components and the <span class="hlt">pressure</span>) which necessitate the solution of four equations (the projection of Newton's law on each axis and mass conservation). By comparison, the Laplace equation is scalar with a single unknown at each node. The objective of this work is to replace the Stokes equations by an elliptical equation with a space dependent permeability. More precisely, the local permeability k is supposed to be proportional to (r-alpha)**2 where r is the distance of the voxel to the closest wall, and alpha a constant; k is zero in the solid phase. The elliptical equation is div(k gradp)=0. A macroscopic <span class="hlt">pressure</span> gradient is assumed to be exerted on the medium and again the resulting velocity averaged over space yields a permeability K_L. In order to validate this method, systematic calculations have been performed. First, elementary shapes (plane channel, circular pipe, rectangular channels) were studied for which flow occurs along parallel lines in which case KL is the arithmetic average of the k's. KL was calculated for various discretizations of the <span class="hlt">pore</span> space and various values of alpha. For alpha=0.5, the agreement with the exact analytical value of KS is excellent for the plane and rectangular channels while it is only approximate for circular pipes. Second, the permeability KL of channels with sinusoidal walls was calculated and compared with analytical results and numerical ones provided by a Lattice Boltzmann algorithm. Generally speaking, the discrepancy does not exceed 25% when</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/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.osti.gov/biblio/5675602-chromosomal-abnormalities-human-sperm','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/5675602-chromosomal-abnormalities-human-sperm"><span>Chromosomal <span class="hlt">abnormalities</span> in human sperm</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Martin, R.H.</p> <p>1985-01-01</p> <p>The ability to analyze human sperm chromosome complements after penetration of zona pellucida-free hamster eggs provides the first opportunity to study the frequency and type of chromosomal <span class="hlt">abnormalities</span> in human gametes. Two large-scale studies have provided information on normal men. We have studied 1,426 sperm complements from 45 normal men and found an <span class="hlt">abnormality</span> rate of 8.9%. Brandriff et al. (5) found 8.1% <span class="hlt">abnormal</span> complements in 909 sperm from 4 men. The distribution of numerical and structural <span class="hlt">abnormalities</span> was markedly dissimilar in the 2 studies. The frequency of aneuploidy was 5% in our sample and only 1.6% in Brandriff's, perhapsmore » reflecting individual variability among donors. The frequency of 24,YY sperm was low: 0/1,426 and 1/909. This suggests that the estimates of nondisjunction based on fluorescent Y body data (1% to 5%) are not accurate. We have also studied men at increased risk of sperm chromosomal <span class="hlt">abnormalities</span>. The frequency of chromosomally unbalanced sperm in 6 men heterozygous for structural <span class="hlt">abnormalities</span> varied dramatically: 77% for t11;22, 32% for t6;14, 19% for t5;18, 13% for t14;21, and 0% for inv 3 and 7. We have also studied 13 cancer patients before and after radiotherapy and demonstrated a significant dose-dependent increase of sperm chromosome <span class="hlt">abnormalities</span> (numerical and structural) 36 months after radiation treatment.« less</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.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/scitech">SciTech Connect</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://cfpub.epa.gov/si/si_public_record_report.cfm?dirEntryId=126965&Lab=NRMRL&keyword=non+AND+equivalent+AND+control&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=126965&Lab=NRMRL&keyword=non+AND+equivalent+AND+control&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>INVESTIGATIONS INTO BIOFOULING PHENOMENA IN FINE <span class="hlt">PORE</span> AERATION DEVICES</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>Microbiologically-based procedures were used to describe biofouling phenomena on fine <span class="hlt">pore</span> aeration devices and to determine whether biofilm characteristics could be related to diffuser process performance parameters. Fine <span class="hlt">pore</span> diffusers were obtained from five municipal wastewa...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4023328','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4023328"><span>Esophageal motility <span class="hlt">abnormalities</span> in gastroesophageal reflux disease</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Martinucci, Irene; de Bortoli, Nicola; Giacchino, Maria; Bodini, Giorgia; Marabotto, Elisa; Marchi, Santino; Savarino, Vincenzo; Savarino, Edoardo</p> <p>2014-01-01</p> <p>Esophageal motility <span class="hlt">abnormalities</span> are among the main factors implicated in the pathogenesis of gastroesophageal reflux disease. The recent introduction in clinical and research practice of novel esophageal testing has markedly improved our understanding of the mechanisms contributing to the development of gastroesophageal reflux disease, allowing a better management of patients with this disorder. In this context, the present article intends to provide an overview of the current literature about esophageal motility dysfunctions in patients with gastroesophageal reflux disease. Esophageal manometry, by recording intraluminal <span class="hlt">pressure</span>, represents the gold standard to diagnose esophageal motility <span class="hlt">abnormalities</span>. In particular, using novel techniques, such as high resolution manometry with or without concurrent intraluminal impedance monitoring, transient lower esophageal sphincter (LES) relaxations, hypotensive LES, ineffective esophageal peristalsis and bolus transit <span class="hlt">abnormalities</span> have been better defined and strongly implicated in gastroesophageal reflux disease development. Overall, recent findings suggest that esophageal motility <span class="hlt">abnormalities</span> are increasingly prevalent with increasing severity of reflux disease, from non-erosive reflux disease to erosive reflux disease and Barrett’s esophagus. Characterizing esophageal dysmotility among different subgroups of patients with reflux disease may represent a fundamental approach to properly diagnose these patients and, thus, to set up the best therapeutic management. Currently, surgery represents the only reliable way to restore the esophagogastric junction integrity and to reduce transient LES relaxations that are considered to be the predominant mechanism by which gastric contents can enter the esophagus. On that ground, more in depth future studies assessing the pathogenetic role of dysmotility in patients with reflux disease are warranted. PMID:24868489</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('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> </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('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('https://medlineplus.gov/ency/article/003242.htm','NIH-MEDLINEPLUS'); return false;" href="https://medlineplus.gov/ency/article/003242.htm"><span>Skin - <span class="hlt">abnormally</span> dark or light</span></a></p> <p><a target="_blank" href="http://medlineplus.gov/">MedlinePlus</a></p> <p></p> <p></p> <p>... page: //medlineplus.gov/ency/article/003242.htm <span class="hlt">Abnormally</span> dark or light skin To use the sharing features ... The bronze color can range from light to dark (in fair-skinned people) with the degree of ...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/12785293','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/12785293"><span>Biochemical <span class="hlt">abnormalities</span> in neonatal seizures.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Sood, Arvind; Grover, Neelam; Sharma, Roshan</p> <p>2003-03-01</p> <p>The presence of seizure does not constitute a diagnoses but it is a symptom of an underlying central nervous system disorder due to systemic or biochemical disturbances. Biochemical disturbances occur frequently in the neonatal seizures either as an underlying cause or as an associated <span class="hlt">abnormality</span>. In their presence, it is difficult to control seizure and there is a risk of further brain damage. Early recognition and treatment of biochemical disturbances is essential for optimal management and satisfactory long term outcome. The present study was conducted in the department of pediatrics in IGMC Shimla on 59 neonates. Biochemical <span class="hlt">abnormalities</span> were detected in 29 (49.15%) of cases. Primary metabolic <span class="hlt">abnormalities</span> occurred in 10(16.94%) cases of neonatal seizures, most common being hypocalcaemia followed by hypoglycemia, other metabolic <span class="hlt">abnormalities</span> include hypomagnesaemia and hyponateremia. Biochemical <span class="hlt">abnormalities</span> were seen in 19(38.77%) cases of non metabolic seizure in neonates. Associated metabolic <span class="hlt">abnormalities</span> were observed more often with Hypoxic-ischemic-encephalopathy (11 out of 19) cases and hypoglycemia was most common in this group. No infant had hyponateremia, hyperkelemia or low zinc level.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/19469742','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/19469742"><span>Electrocardiographic <span class="hlt">abnormalities</span> in opiate addicts.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Wallner, Christina; Stöllberger, Claudia; Hlavin, Anton; Finsterer, Josef; Hager, Isabella; Hermann, Peter</p> <p>2008-12-01</p> <p>To determine in a cross-sectional study the prevalence of electrocardiographic (ECG) <span class="hlt">abnormalities</span> in opiate addicts who were therapy-seeking and its association with demographic, clinical and drug-specific parameters. In consecutive therapy-seeking opiate addicts, a 12-lead ECG was registered within 24 hours after admission and evaluated according to a pre-set protocol between October 2004 and August 2006. Additionally, demographic, clinical and drug-specific parameters were recorded. Included were 511 opiate-addicts, 25% female, with a mean age of 29 years (range 17-59 years). One or more ECG <span class="hlt">abnormalities</span> were found in 314 patients (61%). In the 511 patients we found most commonly ST <span class="hlt">abnormalities</span> (19%), QTc prolongation (13%), tall R- and/or S-waves (11%) and missing R progression (10%). ECG <span class="hlt">abnormalities</span> were more common in males than in females (64 versus 54%, P < 0.05), and in patients with positive than negative urine findings for cannabis (68 versus 57%, P < 0.05). Patients with ST <span class="hlt">abnormalities</span> were more often males than females (21 versus 11%, P < 0.05), had a history of seizures less often (16 versus 27%, P < 0.05), had positive than negative urine findings for cannabis more often (26 versus 15%, P < 0.01) and had negative than positive urine findings for methadone more often (21 versus 11%, P < 0.05). QTc prolongation was more frequent in patients with high dosages of maintenance drugs than in patients with medium or low dosages (27 versus 12 versus 10%, P < 0.05) and in patients whose urine findings were positive than negative for methadone (23 versus 11%, P < 0.001) as well as for benzodiazepines (17 versus 9%, P < 0.05). Limitations of the data are that in most cases other risk factors for the cardiac <span class="hlt">abnormalities</span> were not known. ECG <span class="hlt">abnormalities</span> are frequent in opiate addicts. The most frequent ECG <span class="hlt">abnormalities</span> are ST <span class="hlt">abnormalities</span>, QTc prolongation and tall R- and/or S-waves. ST <span class="hlt">abnormalities</span> are associated with cannabis, and QTc prolongation</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/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('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.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/scitech">SciTech Connect</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://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('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.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://pubs.er.usgs.gov/publication/70017676','USGSPUBS'); return false;" href="https://pubs.er.usgs.gov/publication/70017676"><span>Displacement of soil <span class="hlt">pore</span> water by trichloroethylene</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Wershaw, R. L.; Aiken, G.R.; Imbrigiotta, T.E.; Goldberg, M.C.</p> <p>1994-01-01</p> <p>Dense nonaqueous phase liquids (DNAPLS) are important pollutants because of their widespread use as chemical and industrial solvents. An example of the pollution caused by the discharge of DNAPLs is found at the Picatinny Arsenal, New Jersey, where trichloroethylene (TCE) has been discharged directly into the unsaturated zone. This discharge has resulted in the formation of a plume of TCE-contaminated water in the aquifer downgradient of the discharge. A zone of dark-colored groundwater containing a high dissolved organic C content has been found near the point of discharge of the TCE. The colored-water plume extends from the point of discharge at least 30 m (100 feet) downgradient. Fulvic acids isolated from the colored-waters plume, from water from a background well that has not been affected by the discharge of chlorinated solvents, and from soil <span class="hlt">pore</span> water collected in a lysimeter installed at an uncontaminated site upgradient of the study area have been compared. Nuclear magnetic resonance spectra of the fulvic acids from the colored waters and from the lysimeter are very similar, but are markedly different from the nuclear magnetic resonance spectrum of the fulvic acid from the background well. The three-dimensional fluorescence spectrum and the DOC fractionation profile of the colored groundwater and the soil <span class="hlt">pore</span> water are very similar to each other, but quite different from those of the background water. It is proposed from these observations that this colored water is soil <span class="hlt">pore</span> water that has been displaced by a separate DNAPL liquid phase downward to the saturated zone.</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://ntrs.nasa.gov/search.jsp?R=MSFC-0300209&hterms=international+space+station+images&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3Dinternational%2Bspace%2Bstation%2Bimages','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=MSFC-0300209&hterms=international+space+station+images&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3Dinternational%2Bspace%2Bstation%2Bimages"><span><span class="hlt">Pore</span> Formation and Mobility Investigation video images</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p></p> <p>2003-01-01</p> <p>Video images sent to the ground allow scientists to watch the behavior of the bubbles as they control the melting and freezing of the material during the <span class="hlt">Pore</span> Formation and Mobility Investigation (PFMI) in the Microgravity Science Glovebox aboard the International Space Station. While the investigation studies the way that metals behave at the microscopic scale on Earth -- and how voids form -- the experiment uses a transparent material called succinonitrile that behaves like a metal to study this problem. The bubbles do not float to the top of the material in microgravity, so they can study their interactions.</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.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/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('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('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('https://medlineplus.gov/ency/article/003303.htm','NIH-MEDLINEPLUS'); return false;" href="https://medlineplus.gov/ency/article/003303.htm"><span>Pinna <span class="hlt">abnormalities</span> and low-set ears</span></a></p> <p><a target="_blank" href="http://medlineplus.gov/">MedlinePlus</a></p> <p></p> <p></p> <p>... Pinna <span class="hlt">abnormalities</span>; Genetic defect - pinna; Congenital defect - pinna Images Ear <span class="hlt">abnormalities</span> Pinna of the newborn ear References Haddad J, Keesecker S. Congenital malformations. In: Kliegman RM, Stanton BF, ...</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/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/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> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20040088058&hterms=pacemaker&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D90%26Ntt%3Dpacemaker','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20040088058&hterms=pacemaker&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D90%26Ntt%3Dpacemaker"><span>Complex patterns of <span class="hlt">abnormal</span> heartbeats</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Schulte-Frohlinde, Verena; Ashkenazy, Yosef; Goldberger, Ary L.; Ivanov, Plamen Ch; Costa, Madalena; Morley-Davies, Adrian; Stanley, H. Eugene; Glass, Leon</p> <p>2002-01-01</p> <p>Individuals having frequent <span class="hlt">abnormal</span> heartbeats interspersed with normal heartbeats may be at an increased risk of sudden cardiac death. However, mechanistic understanding of such cardiac arrhythmias is limited. We present a visual and qualitative method to display statistical properties of <span class="hlt">abnormal</span> heartbeats. We introduce dynamical "heartprints" which reveal characteristic patterns in long clinical records encompassing approximately 10(5) heartbeats and may provide information about underlying mechanisms. We test if these dynamics can be reproduced by model simulations in which <span class="hlt">abnormal</span> heartbeats are generated (i) randomly, (ii) at a fixed time interval following a preceding normal heartbeat, or (iii) by an independent oscillator that may or may not interact with the normal heartbeat. We compare the results of these three models and test their limitations to comprehensively simulate the statistical features of selected clinical records. This work introduces methods that can be used to test mathematical models of arrhythmogenesis and to develop a new understanding of underlying electrophysiologic mechanisms of cardiac arrhythmia.</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/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.ncbi.nlm.nih.gov/pubmed/28974593','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/28974593"><span>Endocrine <span class="hlt">abnormalities</span> in lithium toxicity.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Shanks, Gabriella; Mishra, Vinita; Nikolova, Stanka</p> <p>2017-10-01</p> <p>Lithium toxicity can manifest as a variety of biochemical -<span class="hlt">abnormalities</span>. This case report describes a patient -presenting to the emergency department with neuropsychiatric -symptoms on a background of bipolar disorder, for which she was prescribed lithium for 26 years previously. Cases of lithium toxicity are rare but can be severe and this case report -demonstrates to clinicians that they must be thorough in investigating patients with lithium toxicity, as there are many potential <span class="hlt">abnormalities</span> that can manifest concurrently. © Royal College of Physicians 2017. All rights reserved.</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/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('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('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('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/scitech">SciTech Connect</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.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.