Superlight Adsorbent Sponges Based on Graphene Oxide Cross-Linked with Poly(vinyl alcohol) for Continuous Flow Adsorption.

PubMed

Li, Xianfeng; Liu, Tao; Wang, Daohui; Li, Qing; Liu, Zhen; Li, Nana; Zhang, Yufeng; Xiao, Changfa; Feng, Xianshe

2018-06-12

In this study, superlight adsorbent sponges (bulk density 0.016-0.049 g·cm -3 ) were developed based on graphene oxide (GO) cross-linked with poly(vinyl alcohol) (PVA). The interlayer spacing of the GO nanosheets was increased by the insertion of PVA, and good mechanical integrity was attained by the cross-linked structure. They showed excellent continuous flow adsorption capacity (CFAC) when methylene blue (MB) was used as a model contaminant; a water flux of 396 L·m -2 ·h -1 through a 2 cm thick adsorbent sponge was achieved at a hydraulic head of only 10 cm water, with an almost complete retention of MB. They corresponded to a water permeability of 4.0 × 10 5 L·m -2 ·h -1 ·MPa -1 , which was several orders of magnitudes higher than GO-based membranes for similar applications reported in the literature. The GO nanosheets were completely immobilized in the sponge by cross-linking with PVA, and thus, there was no GO nanoparticle leaching or flushing out into the treated permeate water, which was another advantage over direct use of GO powders in water treatment. Because of the high water permeability and CFAC, the cross-linked GO/PVA sponges have a great potential for wastewater treatment.

Estimation of relative permeability and capillary pressure from mass imbibition experiments

NASA Astrophysics Data System (ADS)

Alyafei, Nayef; Blunt, Martin J.

2018-05-01

We perform spontaneous imbibition experiments on three carbonates - Estaillades, Ketton, and Portland - which are three quarry limestones that have very different pore structures and span wide range of permeability. We measure the mass of water imbibed in air saturated cores as a function of time under strongly water-wet conditions. Specifically, we perform co-current spontaneous experiments using a highly sensitive balance to measure the mass imbibed as a function of time for the three rocks. We use cores measuring 37 mm in diameter and three lengths of approximately 76 mm, 204 mm, and 290 mm. We show that the amount imbibed scales as the square root of time and find the parameter C, where the volume imbibed per unit cross-sectional area at time t is Ct1/2. We find higher C values for higher permeability rocks. Employing semi-analytical solutions for one-dimensional flow and using reasonable estimates of relative permeability and capillary pressure, we can match the experimental data. We finally discuss how, in combination with conventional measurements, we can use theoretical solutions and imbibition measurements to find or constrain relative permeability and capillary pressure.

GPR monitoring for non-uniform infiltration through a high permeable gravel layer in the test sand box

NASA Astrophysics Data System (ADS)

Kuroda, Seiichiro; Ishii, Nobuyuki; Morii, Toshihiro

2017-04-01

Recently capillary barriers have been known as a method to protect subsurface regions against infiltration from soil surface. It has essentially non-uniform structure of permeability or soil physical property. To identify the function of the capillary barrier, the site-characterization technique for non-uniform soil moisture distribution and infiltration process is needed. We built a sand box in which a thin high-permeable gravel layer was embedded and conducted a infiltration test, including non-uniform flow of soil water induced by capillary barrier effects. We monitored this process by various types of GPR measurements, including time-lapsed soundings with multi-frequency antenna and transmission measurements like one using cross-borehole radar. Finally we will discuss the applicability of GPR for monitoring the phenomena around the capillary barrier of soil. This work has partially supported by JSPS Grant-in-aid Scientific Research program, No.16H02580.

Facies-controlled fluid migration patterns and subsequent reservoir collapse by depressurization - the Entrada Sandstone, Utah

NASA Astrophysics Data System (ADS)

Sundal, A.; Skurtveit, E.; Midtkandal, I.; Hope, I.; Larsen, E.; Kristensen, R. S.; Braathen, A.

2016-12-01

The thick and laterally extensive Middle Jurassic Entrada Sandstone forms a regionally significant reservoir both in the subsurface and as outcrops in Utah. Individual layers of fluvial sandstone within otherwise fine-grained aeolian dunes and silty inter-dune deposits of the Entrada Earthy Member are of particular interest as CO2 reservoir analogs to study injectivity, reservoir-caprock interaction and bypass systems. Detailed mapping of facies and deformation structures, including petrographic studies and core plug tests, show significant rock property contrasts between layers of different sedimentary facies. Beds representing fluvial facies appear as white, medium-grained, well-sorted and cross-stratified sandstone, displaying high porosity, high micro-scale permeability, low tensile strength, and low seismic velocity. Subsequent to deposition, these beds were structurally deformed and contain a dense network of deformation bands, especially in proximity to faults and injectites. Over- and underlying low-permeability layers of inter-dune aeolian facies contain none or few deformation bands, display significantly higher rock strengths and high seismic velocities compared to the fluvial inter-beds. Permeable units between low-permeability layers are prone to become over-pressured during burial, and the establishment of fluid escape routes during regional tectonic events may have caused depressurization and selective collapse of weak layers. Through-cutting, vertical sand pipes display large clasts of stratified sandstone suspended in remobilized sand matrix, and may have served as permeable fluid conduits and pressure vents before becoming preferentially cemented and plugged. Bleached zones around faults and fractures throughout the succession indicate leakage and migration of reducing fluids. The fluvial beds are porous and would appear in wireline logs and seismic profiles as excellent reservoirs; whereas due to dense populations of deformation bands they may in fact display reduced horizontal and vertical permeability locally. Facies-related differences in geomechanical properties, pressure distribution and selective structural collapse have significant implications for injectivity and reservoir behavior.

Differential permissivity of human cerebrovascular endothelial cells to enterovirus infection and specificities of serotype EV-A71 in crossing an in vitro model of the human blood-brain barrier.

PubMed

Volle, Romain; Archimbaud, Christine; Couraud, Pierre-Olivier; Romero, Ignacio A; Weksler, Babette; Mirand, Audrey; Pereira, Bruno; Henquell, Cécile; Peigue-Lafeuille, Hélène; Bailly, Jean-Luc

2015-07-01

Human cerebral microvascular endothelial cells (hCMEC/D3 cell line) form a steady polarized barrier when cultured in vitro on a permeable membrane. Their susceptibility to enterovirus (EV) strains was analysed to investigate how these viruses may cross the blood-brain barrier. A sample of 88 virus strains was selected on phylogenetic features amongst 43 epidemiologically relevant types of the four EV species A-D. The EV-A71 genome was replicated at substantial rates, whilst the infectious virus was released at extremely low but sustained rates at both barrier sides for at least 4 days. EV-A71 antigens were detected in a limited number of cells. The properties of the endothelial barrier (structure and permeability) remained intact throughout infection. The chronic EV-A71 infection was in sharp contrast to the productive infection of cytolytic EVs (e.g. echoviruses E-6 and E-30). The hCMEC/D3 barriers infected with the latter EVs exhibited elevated proportions of apoptotic and necrotic cells, which resulted in major injuries to the endothelial barriers with a dramatic increase of paracellular permeability and virus crossing to the abluminal side. The following intracellular rearrangements were also seen: early destruction of the actin cytoskeleton, remodelling of intracellular membranes and reorganization of the mitochondrion network in a small cluster near the perinuclear space.

Deep permeability of the San Andreas Fault from San Andreas Fault Observatory at Depth (SAFOD) core samples

USGS Publications Warehouse

Morrow, Carolyn A.; Lockner, David A.; Moore, Diane E.; Hickman, Stephen H.

2014-01-01

The San Andreas Fault Observatory at Depth (SAFOD) scientific borehole near Parkfield, California crosses two actively creeping shear zones at a depth of 2.7 km. Core samples retrieved from these active strands consist of a foliated, Mg-clay-rich gouge containing porphyroclasts of serpentinite and sedimentary rock. The adjacent damage zone and country rocks are comprised of variably deformed, fine-grained sandstones, siltstones, and mudstones. We conducted laboratory tests to measure the permeability of representative samples from each structural unit at effective confining pressures, Pe up to the maximum estimated in situ Pe of 120 MPa. Permeability values of intact samples adjacent to the creeping strands ranged from 10−18 to 10−21 m2 at Pe = 10 MPa and decreased with applied confining pressure to 10−20–10−22 m2 at 120 MPa. Values for intact foliated gouge samples (10−21–6 × 10−23 m2 over the same pressure range) were distinctly lower than those for the surrounding rocks due to their fine-grained, clay-rich character. Permeability of both intact and crushed-and-sieved foliated gouge measured during shearing at Pe ≥ 70 MPa ranged from 2 to 4 × 10−22 m2 in the direction perpendicular to shearing and was largely insensitive to shear displacement out to a maximum displacement of 10 mm. The weak, actively-deforming foliated gouge zones have ultra-low permeability, making the active strands of the San Andreas Fault effective barriers to cross-fault fluid flow. The low matrix permeability of the San Andreas Fault creeping zones and adjacent rock combined with observations of abundant fractures in the core over a range of scales suggests that fluid flow outside of the actively-deforming gouge zones is probably fracture dominated.

Do Bat Gantries and Underpasses Help Bats Cross Roads Safely?

PubMed Central

Berthinussen, Anna; Altringham, John

2012-01-01

Major roads can reduce bat abundance and diversity over considerable distances. To mitigate against these effects and comply with environmental law, many European countries install bridges, gantries or underpasses to make roads permeable and safer to cross. However, through lack of appropriate monitoring, there is little evidence to support their effectiveness. Three underpasses and four bat gantries were investigated in northern England. Echolocation call recordings and observations were used to determine the number of bats using underpasses in preference to crossing the road above, and the height at which bats crossed. At gantries, proximity to the gantry and height of crossing bats were measured. Data were compared to those from adjacent, severed commuting routes that had no crossing structure. At one underpass 96% of bats flew through it in preference to crossing the road. This underpass was located on a pre-construction commuting route that allowed bats to pass without changing flight height or direction. At two underpasses attempts to divert bats from their original commuting routes were unsuccessful and bats crossed the road at the height of passing vehicles. Underpasses have the potential to allow bats to cross roads safely if built on pre-construction commuting routes. Bat gantries were ineffective and used by a very small proportion of bats, even up to nine years after construction. Most bats near gantries crossed roads along severed, pre-construction commuting routes at heights that put them in the path of vehicles. Crossing height was strongly correlated with verge height, suggesting that elevated verges may have some value in mitigation, but increased flight height may be at the cost of reduced permeability. Green bridges should be explored as an alternative form of mitigation. Robust monitoring is essential to assess objectively the case for mitigation and to ensure effective mitigation. PMID:22719941

Cross-formational flow of water into coalbed methane reservoirs: controls on relative permeability curve shape and production profile

PubMed Central

Karacan, C. Özgen

2017-01-01

Coalbed methane (CBM) wells tend to produce large volumes of water, especially when there is hydraulic connectivity between coalbed and nearby formations. Cross-formational flow between producing coal and adjacent formations can have significant production and environmental implications, affecting economic viability of production from these shallow reservoirs. Such flows can also affect how much gas can be removed from a coalbed prior to mining and thus can have implications for methane control in mining as well. The aim of this paper is to investigate the impact of water flow from an external source into coalbed on production performance and also on reservoir variables including cleat porosity and relative permeability curves derived from production data analysis. A reservoir model is constructed to investigate the production performance of a CBM well when cross-formational flow is present between the coalbed and the overlying formation. Results show that cleat porosity calculated by analysis of production data can be more than one order of magnitude higher than actual cleat porosity. Due to hydraulic connectivity, water saturation within coalbed does not considerably change for a period of time, and hence, the peak of gas production is delayed. Upon depletion of the overlying formation, water saturation in coalbed quickly decreases. Rapid decline of water saturation in the coalbed corresponds to a sharp increase in gas production. As an important consequence, when cross-flow is present, gas and water relative permeability curves, derived from simulated production data, have distinctive features compared to the initial relative permeability curves. In the case of cross-flow, signatures of relative permeability curves are concave downward and low gas permeability for a range of water saturation, followed by rapid increase afterward for water and gas, respectively. The results and analyses presented in this work can help to assess the impact of cross-formational flow on reservoir variables derived from production data analysis and can also contribute to identifying hydraulic connectivity between coalbed and adjacent formations. PMID:28626492

Low resistivity and permeability in actively deforming shear zones on the San Andreas Fault at SAFOD

USGS Publications Warehouse

Morrow, Carolyn A.; Lockner, David A.; Hickman, Stephen H.

2015-01-01

The San Andreas Fault Observatory at Depth (SAFOD) scientific drillhole near Parkfield, California crosses the San Andreas Fault at a depth of 2.7 km. Downhole measurements and analysis of core retrieved from Phase 3 drilling reveal two narrow, actively deforming zones of smectite-clay gouge within a roughly 200 m-wide fault damage zone of sandstones, siltstones and mudstones. Here we report electrical resistivity and permeability measurements on core samples from all of these structural units at effective confining pressures up to 120 MPa. Electrical resistivity (~10 ohm-m) and permeability (10-21 to 10-22 m2) in the actively deforming zones were one to two orders of magnitude lower than the surrounding damage zone material, consistent with broader-scale observations from the downhole resistivity and seismic velocity logs. The higher porosity of the clay gouge, 2 to 8 times greater than that in the damage zone rocks, along with surface conduction were the principal factors contributing to the observed low resistivities. The high percentage of fine-grained clay in the deforming zones also greatly reduced permeability to values low enough to create a barrier to fluid flow across the fault. Together, resistivity and permeability data can be used to assess the hydrogeologic characteristics of the fault, key to understanding fault structure and strength. The low resistivities and strength measurements of the SAFOD core are consistent with observations of low resistivity clays that are often found in the principal slip zones of other active faults making resistivity logs a valuable tool for identifying these zones.

Geostatistics applied to cross-well reflection seismic for imaging carbonate aquifers

NASA Astrophysics Data System (ADS)

Parra, Jorge; Emery, Xavier

2013-05-01

Cross-well seismic reflection data, acquired from a carbonate aquifer at Port Mayaca test site near the eastern boundary of Lake Okeechobee in Martin County, Florida, are used to delineate flow units in the region intercepted by two wells. The interwell impedance determined by inversion from the seismic reflection data allows us to visualize the major boundaries between the hydraulic units. The hydraulic (flow) unit properties are based on the integration of well logs and the carbonate structure, which consists of isolated vuggy carbonate units and interconnected vug systems within the carbonate matrix. The vuggy and matrix porosity logs based on Formation Micro-Imager (FMI) data provide information about highly permeable conduits at well locations. The integration of the inverted impedance and well logs using geostatistics helps us to assess the resolution of the cross-well seismic method for detecting conduits and to determine whether these conduits are continuous or discontinuous between wells. A productive water zone of the aquifer outlined by the well logs was selected for analysis and interpretation. The ELAN (Elemental Log Analysis) porosity from two wells was selected as primary data and the reflection seismic-based impedance as secondary data. The direct and cross variograms along the vertical wells capture nested structures associated with periodic carbonate units, which correspond to connected flow units between the wells. Alternatively, the horizontal variogram of impedance (secondary data) provides scale lengths that correspond to irregular boundary shapes of flow units. The ELAN porosity image obtained by cokriging exhibits three similar flow units at different depths. These units are thin conduits developed in the first well and, at about the middle of the interwell separation region, these conduits connect to thicker flow units that are intercepted by the second well. In addition, a high impedance zone (low porosity) at a depth of about 275 m, after being converted to ELAN porosity, is characterized as a more confined low porosity structure. This continuous zone corresponds to a permeability barrier in the carbonate aquifer that separates the three connected conduits observed in the cokriging image. In the zones above and below this permeability barrier, the water production is very high, which agrees with water well observations at the Port Mayaca aquifer.

A Physiologically Based Pharmacokinetic Model for the Oxime TMB-4: Simulation of Rodent and Human Data

DTIC Science & Technology

2013-01-13

concentration gradient–driven diffusion across the membranes, but also on the permeability area (PA) cross product for the tissue, which slows the pene...or slowly (mus- cle, skin, bone) perfused tissues. Diffusion limitation con- stants (permeability area cross products or PAs), metabolism and...al. 1991; Worek et al. 2005). A PBPK model has the advan- tage of interspecies and cross -route extrapolation. This PBPK model was initially developed

Studies of the permeation properties of glomerular basement membrane: cross-linking renders glomerular basement membrane permeable to protein.

PubMed

Walton, H A; Byrne, J; Robinson, G B

1992-03-20

Cross-linking glomerular basement membrane (GBM) has been shown to render it more permeable to protein. Isolated pig GBM was cross-linked with dimethylmalonimidate which reacts selectively with lysine epsilon-NH2 groups or with glutaraldehyde, a less selective cross-linking agent. Studies of the ultrafiltration properties of these materials in vitro using cytochrome c, myoglobin, bovine serum albumin and immunoglobulin showed that cross-linking had markedly increased solvent and protein fluxes as compared with native membranes particularly at higher pressures. Filtration studies with serum demonstrated that the cross-linked membranes were more permeable to serum proteins. Thickness measurements under pressure indicated that cross-linked membrane was less compressed than native membrane as pressure was increased. Pore theory did not provide a suitable model for analysis of the results, but analysis of the results using the fibre-matrix hypothesis indicated that cross-linking had the effect of bundling together the fibres (type IV collagen) in the GBM matrix. The effect of cross-linking on filtration could be explained by a combination of contraction of the membrane, fibre bundling and increased rigidity compared with native membrane. Cross-linking of GBM might lead to long-term damage of the glomerular capillary wall in nephritis, so promoting proteinuria.

Practical characterization of eolian reservoirs for development: Nugget Sandstone, Utah—Wyoming thrust belt

NASA Astrophysics Data System (ADS)

Lindquist, Sandra J.

1988-04-01

The Jurassic eolian Nugget Sandstone of the Utah-Wyoming thrust belt is a texturally heterogeneous formation with anisotropic reservoir inherited primarily from the depositional environment. Original reservoir quality has been reduced somewhat by cementation and slightly enhanced by dissolution. Low-permeability, gouge-filled micro-faults compartmentalize the formation, whereas intermittently open fractures provide effective permeability paths locally. Where productive, the Nugget Sandstone ranges from approximately 800 to 1050 ft (244-320 m) thick at subsurface depths of 7500 to 15,000 ft (2286-4572 m). Porosity ranges from several percent to 25%, and permeability covers five orders of magnitude from hundredths of milliDarcies to Darcies. Some Nugget reservoirs are fully charged with hydrocarbons. Different stratification types have unique depositional textures, primary and diagenetic mineralogies, and deformational fabrics resulting in characteristic porosity, permeability, permeability directionality, and pore geometry attributes. Such characteristics can be determined from core analysis, mercury injection, nuclear magnetic resonance, conventional log, dipmeter and production data. Nugget dune deposits (good reservoir facies) primarily consist of grainflow and wind-ripple cross-strata, the former of which have the better reservoir quality and the lesser heterogeneity in bedding texture. High-permeability facies are commonly affected by local quartz and nodular carbonate cementation, chlorite (and lesser illite) precipitation, and minor framework and cement dissolution. Gouge-filled micro-faults are the predominant deformational overprint. Interdune, sand-sheet, and other water-associated deposits (poor reservoir facies) are characterized by low-angle wind-ripple laminae and more irregular bedding, some of which is associated with damp or wet conditions. Water-associated Nugget stratification generally contains the finest grained depositional textures and has the poorest reservoir properties. These non-dune facies contain intergranular micritic carbonate and illite precipitates and are most affected by compaction and pressure solution phenomena. Open types of fractures are somewhat more likely in this lower permeability rock. Depositional models incorporating dune morphologies, facies distribution, permeability directionality, and theoretical concepts regarding dune migration through time are useful in delineating correlative intervals most likely to have continuity and potential communication of reservoir properties. Stratigraphic models can be adapted for reservoir simulation studies and also can be utilized in solving structural resolution problems if correlatable vertical sequences and relatively consistent cross-strata orientations exist.

Monitoring CO2 penetration and storage in the brine-saturated low permeable sandstone by the geophysical exploration technologies

NASA Astrophysics Data System (ADS)

Honda, H.; Mitani, Y.; Kitamura, K.; Ikemi, H.; Imasato, M.

2017-12-01

Carbon dioxide (CO2) capture and storage (CCS) plays a vital role in reducing greenhouse gas emissions. In the northern part of Kyushu region of Japan, complex geological structure (Coalfield) is existed near the CO2 emission source and has 1.06 Gt of CO2 storage capacity. The geological survey shows that these layers are formed by low permeable sandstone. It is necessary to monitor the CO2 behavior and clear the mechanisms of CO2 penetration and storage in the low permeable sandstone. In this study, measurements of complex electrical impedance (Z) and elastic wave velocity (P-wave velocity: Vp) were conducted during the supercritical CO2 injection experiment into the brine-saturated low permeable sandstone. The experiment conditions were as follows; Confining pressure: 20 MPa, Initial pore pressure: 10 MPa, 40 °, CO2 injection rate: 0.01 to 0.5 mL/min. Z was measured in the center of the specimen and Vp were measured at three different heights of the specimen at constant intervals. In addition, we measured the longitudinal and lateral strain at the center of the specimen, the pore pressure and CO2 injection volume (CO2 saturation). During the CO2 injection, the change of Z and Vp were confirmed. In the drainage terms, Vp decreased drastically once CO2 reached the measurement cross section.Vp showed the little change even if the flow rate increased (CO2 saturation increased). On the other hand, before the CO2 front reached, Z decreased with CO2-dissolved brine. After that, Z showed continuously increased as the CO2 saturation increased. From the multi-parameter (Hydraulic and Rock-physics parameters), we revealed the detail CO2 behavior in the specimen. In the brine-saturated low permeable sandstone, the slow penetration of CO2 was observed. However, once CO2 has passed, the penetration of CO2 became easy in even for brine-remainded low permeable sandstone. We conclude low permeable sandstone has not only structural storage capacity but also residual tapping (Capillary trapping) capacity. There is a positive possibility to conduct CCS in the low-quality reservoir (low permeable sandstone).

The mechanics and three-dimensional internal structure of active magmatic systems: Kilauea volcano, Hawaii.

USGS Publications Warehouse

Ryan, M.P.

1988-01-01

Interpretation of abundant seismic data suggest that Kilauea's primary conduit within the upper mantle is concentrically zoned to about 34-km depth. This zoned structure is inferred to contain a central core region of relatively higher permeability, surrounded by numerous dikes that are in intermittent hydraulic communication with each other and with the central core. During periods of relatively high magma transport, the entire cross section of the conduit is utilized. During periods of relatively low to moderate transport, however, only the central core is active.-from Author

Pneumatic testing in 45-degree-inclined boreholes in ash-flow tuff near Superior, Arizona

USGS Publications Warehouse

LeCain, G.D.

1995-01-01

Matrix permeability values determined by single-hole pneumatic testing in nonfractured ash-flow tuff ranged from 5.1 to 20.3 * 1046 m2 (meters squared), depending on the gas-injection rate and analysis method used. Results from the single-hole tests showed several significant correlations between permeability and injection rate and between permeability and test order. Fracture permeability values determined by cross-hole pneumatic testing in fractured ash-flow tuff ranged from 0.81 to 3.49 * 1044 m2, depending on injection rate and analysis method used. Results from the cross-hole tests monitor intervals showed no significant correlation between permeability and injection rate; however, results from the injection interval showed a significant correlation between injection rate and permeability. Porosity estimates from the 'cross-hole testing range from 0.8 to 2.0 percent. The maximum temperature change associated with the pneumatic testing was 1.2'(2 measured in the injection interval during cross-hole testing. The maximum temperature change in the guard and monitor intervals was O.Ip C. The maximum error introduced into the permeability values due to temperature fluctuations is approximately 4 percent. Data from temperature monitoring in the borehole indicated a positive correlation between the temperature decrease in the injection interval during recovery testing and the gas-injection rate. The thermocouple psychrometers indicated that water vapor was condensing in the boreholes during testing. The psychrometers in the guard and monitor intervals detected the drier injected gas as an increase in the dry bulb reading. The relative humidity in the test intervals was always higher than the upper measurement limit of the psychrometers. Although the installation of the packer system may have altered the water balance of the borehole, the gas-injection testing resulted in minimal or no changes in the borehole relative humidity.

Experimental scleral cross-linking increases glaucoma damage in a mouse model

PubMed Central

Kimball, Elizabeth C.; Nguyen, Cathy; Steinhart, Matthew R.; Nguyen, Thao D.; Pease, Mary E.; Oglesby, Ericka N.; Oveson, Brian C.; Quigley, Harry A.

2014-01-01

The purpose of this study was to assess the effect of a scleral cross-linking agent on susceptibility to glaucoma damage in a mouse model. CD1 mice underwent 3 subconjunctival injections of 0.5 M glyceraldehyde (GA) in 1 week, then had elevated intraocular pressure (IOP) induced by bead injection. Degree of cross-linking was measured by enzyme-linked immunosorbent assay (ELISA), scleral permeability was measured by fluorescence recovery after photobleaching (FRAP), and the mechanical effects of GA exposure were measured by inflation testing. Control mice had buffer injection or no injection in 2 separate glaucoma experiments. IOP was monitored by Tonolab and retinal ganglion cell (RGC) loss was measured by histological axon counting. To rule out undesirable effects of GA, we performed electroretinography and detailed histology of the retina. GA exposure had no detectable effects on RGC number, retinal structure or function either histologically or electrophysiologically. GA increased cross-linking of sclera by 37% in an ELISA assay, decreased scleral permeability (FRAP, p = 0.001), and produced a steeper pressure—strain behavior by in vitro inflation testing. In two experimental glaucoma experiments, GA-treated eyes had greater RGC axon loss from elevated IOP than either buffer-injected or control eyes, controlling for level of IOP exposure over time (p = 0.01, and 0.049, multivariable regression analyses). This is the first report that experimental alteration of the sclera, by cross-linking, increases susceptibility to RGC damage in mice. PMID:25285424

Prediction of blood-brain barrier permeation of α-adrenergic and imidazoline receptor ligands using PAMPA technique and quantitative-structure permeability relationship analysis.

PubMed

Vucicevic, Jelica; Nikolic, Katarina; Dobričić, Vladimir; Agbaba, Danica

2015-02-20

Imidazoline receptor ligands are a numerous family of biologically active compounds known to produce central hypotensive effect by interaction with both α2-adrenoreceptors (α2-AR) and imidazoline receptors (IRs). Recent hypotheses connect those ligands with several neurological disorders. Therefore some IRs ligands are examined as novel centrally acting antihypertensives and drug candidates for treatment of various neurological diseases. Effective Blood-Brain Barrier (BBB) permeability (P(e)) of 18 IRs/α-ARs ligands and 22 Central Nervous System (CNS) drugs was experimentally determined using Parallel Artificial Membrane Permeability Assay (PAMPA) and studied by the Quantitative-Structure-Permeability Relationship (QSPR) methodology. The dominant molecules/cations species of compounds have been calculated at pH = 7.4. The analyzed ligands were optimized using Density Functional Theory (B3LYP/6-31G(d,p)) included in ChemBio3D Ultra 13.0 program and molecule descriptors for optimized compounds were calculated using ChemBio3D Ultra 13.0, Dragon 6.0 and ADMET predictor 6.5 software. Effective permeability of compounds was used as dependent variable (Y), while calculated molecular parametres were used as independent variables (X) in the QSPR study. SIMCA P+ 12.0 was used for Partial Least Square (PLS) analysis, while the stepwise Multiple Linear Regression (MLR) and Artificial Neural Networks (ANN) modeling were performed using STASTICA Neural Networks 4.0. Predictive potential of the formed models was confirmed by Leave-One-Out Cross- and external-validation and the most reliable models were selected. The descriptors that are important for model building are identified as well as their influence on BBB permeability. Results of the QSPR studies could be used as time and cost efficient screening tools for evaluation of BBB permeation of novel α-adrenergic/imidazoline receptor ligands, as promising drug candidates for treatment of hypertension or neurological diseases. Copyright © 2014 Elsevier B.V. All rights reserved.

Sequence stratigraphy, seismic stratigraphy, and seismic structures of the lower intermediate confining unit and most of the Floridan aquifer system, Broward County, Florida

USGS Publications Warehouse

Cunningham, Kevin J.; Kluesner, Jared W.; Westcott, Richard L.; Robinson, Edward; Walker, Cameron; Khan, Shakira A.

2017-12-08

Deep well injection and disposal of treated wastewater into the highly transmissive saline Boulder Zone in the lower part of the Floridan aquifer system began in 1971. The zone of injection is a highly transmissive hydrogeologic unit, the Boulder Zone, in the lower part of the Floridan aquifer system. Since the 1990s, however, treated wastewater injection into the Boulder Zone in southeastern Florida has been detected at three treated wastewater injection utilities in the brackish upper part of the Floridan aquifer system designated for potential use as drinking water. At a time when usage of the Boulder Zone for treated wastewater disposal is increasing and the utilization of the upper part of the Floridan aquifer system for drinking water is intensifying, there is an urgency to understand the nature of cross-formational fluid flow and identify possible fluid pathways from the lower to upper zones of the Floridan aquifer system. To better understand the hydrogeologic controls on groundwater movement through the Floridan aquifer system in southeastern Florida, the U.S. Geological Survey and the Broward County Environmental Planning and Community Resilience Division conducted a 3.5-year cooperative study from July 2012 to December 2015. The study characterizes the sequence stratigraphy, seismic stratigraphy, and seismic structures of the lower part of the intermediate confining unit aquifer and most of the Floridan aquifer system.Data obtained to meet the study objective include 80 miles of high-resolution, two-dimensional (2D), seismic-reflection profiles acquired from canals in eastern Broward County. These profiles have been used to characterize the sequence stratigraphy, seismic stratigraphy, and seismic structures in a 425-square-mile study area. Horizon mapping of the seismic-reflection profiles and additional data collection from well logs and cores or cuttings from 44 wells were focused on construction of three-dimensional (3D) visualizations of eight sequence stratigraphic cycles that compose the Eocene to Miocene Oldsmar, Avon Park, and Arcadia Formations. The mapping of these seismic-reflection and well data has produced a refined Cenozoic sequence stratigraphic, seismic stratigraphic, and hydrogeologic framework of southeastern Florida. The upward transition from the Oldsmar Formation to the Avon Park Formation and the Arcadia Formation embodies the evolution from (1) a tropical to subtropical, shallow-marine, carbonate platform, represented by the Oldsmar and Avon Park Formations, to (2) a broad, temperate, mixed carbonate-siliciclastic shallow marine shelf, represented by the lower part of the Arcadia Formation, and to (3) a temperate, distally steepened carbonate ramp represented by the upper part of the Arcadia Formation.In the study area, the depositional sequences and seismic sequences have a direct correlation with hydrogeologic units. The approximate upper boundary of four principal permeable units of the Floridan aquifer system (Upper Floridan aquifer, Avon Park permeable zone, uppermost major permeable zone of the Lower Floridan aquifer, and Boulder Zone) have sequence stratigraphic and seismic-reflection signatures that were identified on cross sections, mapped, or both, and therefore the sequence stratigraphy and seismic stratigraphy were used to guide the development of a refined spatial representation of these hydrogeologic units. In all cases, the permeability of the four permeable units is related to stratiform megaporosity generated by ancient dissolution of carbonate rock associated with subaerial exposure and unconformities at the upper surfaces of carbonate depositional cycles of several hierarchical scales ranging from high-frequency cycles to depositional sequences. Additionally, interparticle porosity also contributes substantially to the stratiform permeability in much of the Upper Floridan aquifer. Information from seismic stratigraphy allowed 3D geomodeling of hydrogeologic units—an approach never before applied to this area. Notably, the 3D geomodeling provided 3D visualizations and geocellular models of the depositional sequences, hydrostratigraphy, and structural features. The geocellular data could be used to update the hydrogeologic structure inherent to groundwater flow simulations that are designed to address the sustainability of the water resources of the Floridan aquifer system.Two kinds of pathways that could enable upward cross-formational flow of injected treated wastewater from the Boulder Zone have been identified in the 80 miles of high-resolution seismic data collected for this study: a near-vertical reverse fault and karst collapse structures. The single reverse fault, inferred to be of tectonic origin, is in extreme northeastern Broward County and has an offset of about 19 feet at the level of the Arcadia Formation. Most of the 17 karst collapse structures identified manifest as columniform, vertically stacked sagging seismic reflections that span early Eocene to Miocene age rocks equivalent to much of the Floridan aquifer system and the lower part of the overlying intermediate confining unit. In some cases, the seismic-sag structures extend upward into strata of Pliocene age. The seismic-sag structures are interpreted to have a semicircular shape in plan view on the basis of comparison to (1) other seismic-sag structures in southeastern Florida mapped with two 2D seismic cross lines or 3D data, (2) comparison to these structures located in other carbonate provinces, and (3) plausible extensional ring faults detected with multi-attribute analysis. The seismic-sag structures in the study area have heights as great as 2,500 vertical feet, though importantly, one spans about 7,800 feet. Both multi-attribute analysis and visual detection of offset of seismic reflections within the seismic-sag structures indicate faults and fractures are associated with many of the structures. Multi-attribute analysis highlighting chimney fluid pathways also indicates that the seismic-sag structures have a high probability for potential vertical cross-formational fluid flow along the faulted and fractured structures. A collapse of the seismic-sag structures within a deep burial setting evokes an origin related to hypogenic karst processes by ascending flow of subsurface fluids. In addition, paleo-epigenic karst related to major regional subaerial unconformities within the Florida Platform generated collapse structures (paleo-sinkholes) that are much smaller in scale than the cross-formational seismic-sag structures.

The Importance of Parameter Variances, Correlations Lengths, and Cross-Correlations in Reactive Transport Models: Key Considerations for Assessing the Need for Microscale Information (Invited)

NASA Astrophysics Data System (ADS)

Reimus, P. W.

2010-12-01

A process-oriented modeling approach is implemented to examine the importance of parameter variances, correlation lengths, and especially cross-correlations in contaminant transport predictions over large scales. It is shown that the most important consideration is the correlation between flow rates and retardation processes (e.g., sorption, matrix diffusion) in the system. If flow rates are negatively correlated with retardation factors in systems containing multiple flow pathways, then characterizing these negative correlation(s) may have more impact on reactive transport modeling than microscale information. Such negative correlations are expected in porous-media systems where permeability is negatively correlated with clay content and rock alteration (which are usually associated with increased sorption). Likewise, negative correlations are expected in fractured rocks where permeability is positively correlated with fracture apertures, which in turn are negatively correlated with sorption and matrix diffusion. Parameter variances and correlation lengths are also shown to have important effects on reactive transport predictions, but they are less important than parameter cross-correlations. Microscale information pertaining to contaminant transport has become more readily available as characterization methods and spectroscopic instrumentation have achieved lower detection limits, greater resolution, and better precision. Obtaining detailed mechanistic insights into contaminant-rock-water interactions is becoming a routine practice in characterizing reactive transport processes in groundwater systems (almost necessary for high-profile publications). Unfortunately, a quantitative link between microscale information and flow and transport parameter distributions or cross-correlations has not yet been established. One reason for this is that quantitative microscale information is difficult to obtain in complex, heterogeneous systems, so simple systems that lack the complexity and heterogeneity of real aquifer materials are often studied. Another is that instrumentation used to obtain microscale information often probes only one variable or family of variables at a time, so linkages to other variables must be inferred by indirect means from other lines of evidence. Despite these limitations, microscale information can be useful in the development and validation of reactive transport models. For example, knowledge of mineral phases that have strong affinities for contaminants can help in the development of cross-correlations between flow and sorption parameters via characterization of permeability and mineral distributions in aquifers. Likewise, microscale information on pore structures in low-permeability zones and contaminant penetration distances into these zones from higher-permeability zones (e.g., fractures) can provide valuable constraints on the representation of diffusive mass transfer processes between flowing porosity and secondary porosity. The prioritization of obtaining microscale information in any groundwater system can be informed by modeling exercises such as those conducted for this study.

Estimation of hydraulic permeability considering the micro morphology of rocks of the borehole YAXCOPOIL-1 (Impact crater Chicxulub, Mexico)

NASA Astrophysics Data System (ADS)

Mayr, S. I.; Burkhardt, H.; Popov, Yu.; Wittmann, A.

2008-04-01

Internal surface, formation factor, Nuclear Magnetic Resonance (NMR)-T2 relaxation times and pore radius distributions were measured on representative core samples for the estimation of hydraulic permeability. Permeability is estimated using various versions of the classic Kozeny-Carman-equation (K-C) and a further development of K-C, the fractal PaRiS-model, taking into account the internal surface. In addition to grain and pore size distribution, directly connected to permeability, internal surface reflects the internal structure (“micro morphology”). Lithologies could be grouped with respect to differences in internal surface. Most melt rich impact breccia lithologies exhibit large internal surfaces, while Tertiary post-impact sediments and Cretaceous lithologies in displaced megablocks display smaller internal surfaces. Investigations with scanning electron microscopy confirm the correlation between internal surface and micro morphology. In addition to different versions of K-C, estimations by means of NMR, pore radius distributions and some gas permeability measurements serve for cross-checking and calibration. In general, the different estimations from the independent methods and the measurements are in satisfactory accordance. For Tertiary limestones and Suevites bulk with very high porosities (up to 35%) permeabilites between 10-14 and 10-16 m2 are found, whereas in lower Suevite, Cretaceous anhydrites and dolomites, bulk permeabilites are between 10-15 and 10-23 m2.

Textural evidence for jamming and dewatering of a sub-surface, fluid-saturated granular flow

NASA Astrophysics Data System (ADS)

Sherry, T. J.; Rowe, C. D.; Kirkpatrick, J. D.; Brodsky, E. E.

2011-12-01

Sand injectites are spectacular examples of large-scale granular flows involving migration of hundreds of cubic meters of sand slurry over hundreds of meters to kilometers in the sub-surface. By studying the macro- and microstructural textures of a kilometer-scale sand injectite, we interpret the fluid flow regimes during emplacement and define the timing of formation of specific textures in the injected material. Fluidized sand sourced from the Santa Margarita Fm., was injected upward into the Santa Cruz Mudstone, Santa Cruz County, California. The sand injectite exposed at Yellow Bank Beach records emplacement of both hydrocarbon and aqueous sand slurries. Elongate, angular mudstone clasts were ripped from the wall rock during sand migration, providing evidence for high velocity, turbid flow. However, clast long axis orientations are consistently sub-horizontal suggesting the slurry transitioned to a laminar flow as the flow velocity decreased in the sill-like intrusion. Millimeter to centimeter scale laminations are ubiquitous throughout the sand body and are locally parallel to the mudstone clast long axes. The laminations are distinct in exposure because alternating layers are preferentially cemented with limonite sourced from later groundwater infiltration. Quantitative microstructural analyses show that the laminations are defined by subtle oscillations in grain alignment between limonite and non-limonite stained layers. Grain packing, size and shape distributions do not vary. The presence of limonite in alternating layers results from differential infiltration of groundwater, indicating permeability changes between the layers despite minimal grain scale differences. Convolute dewatering structures deform the laminations. Dolomite-cemented sand, a signature of hydrocarbon saturation, forms irregular bodies that cross-cut the laminations and dewatering structures. Laminations are not formed in the dolomite-cemented sand. The relative viscosity difference between the hydrocarbon and aqueous sand slurries controls the the critical radius of the contacts between dolomite cemented and limonite cemented sand bodies. The cross-cutting relationships established in the field show that the laminations formed at the jamming transition in the aqueous sand slurry. We interpret the laminations as preserving evidence for dynamic permeability instabilities in the dewatering slurry. Relatively high permeability channels formed as pore fluid flow rearranged grains during initial dewatering. Once initiated, the flow localized further into the higher permeability channels resulting in a feedback that caused the permeability in the channels to increase.

Improvement on Physical Properties of Pullulan Films by Novel Cross-Linking Strategy.

PubMed

Chen, Chieh-Ting; Chen, Kuan-I; Chiang, Hsin-Han; Chen, Yu-Kuo; Cheng, Kuan-Chen

2017-01-01

Pullulan based films possess several advantages, including high transparency, low toxicity, good biodegradability, good mechanical properties, and low oxygen permeability, are preferable for food packaging. The application of pullulan films on food packaging, however, has inherent disadvantage of high water solubility. In this study, glutaraldehyde and glycerol were used as the cross-linking reagent and the plasticizer respectively to improve water resistance and physical properties of the pullulan films. Effects of cross-linking degree on physical properties, including water absorptions, swelling behaviors, water vapor permeability and tensile strengths of films were evaluated. FTIR results demonstrated that the pullulan films were successfully cross-linked by glutaraldehyde. The tensile strength of pullulan films could be enhanced significantly (P < 0.05) when glutaraldehyde was between 1% and 5% (w/w); nevertheless, the amount of glutaraldehyde above 20% (w/w) led to films brittleness. With the addition of glycerol as a plasticizer enhanced the extensibility of films as well as the hydrophilicity, resulting in higher water vapor permeability. © 2016 Institute of Food Technologists®.

Bifunctionalized organic-inorganic charged nanocomposite membrane for pervaporation dehydration of ethanol.

PubMed

Tripathi, Bijay P; Kumar, Mahendra; Saxena, Arunima; Shahi, Vinod K

2010-06-01

Chitosan was modified into N-p-carboxy benzyl chitosan (NCBC) by introducing an aromatic ring grafted with acidic -COOH group and highly stable and cross-linked nanostructured NCBC-silica composite membranes were prepared for pervaporation dehydration of water-ethanol mixture. These membranes were tailored to comprise three regions namely: hydrophobic region, highly charged region and selective region, in which weak acidic group (-COOH) was grafted at organic segment while strong acidic group (-SO(3)H) was grafted at inorganic segment to achieve high stability and less swelling in water-ethanol mixture. Cross-linking density and NCBC-silica content in membrane matrix has been systematically optimized to control the nanostructure of the developed polymer matrix for studying the effects of molecular structure on the swelling, and PV performance. Among prepared membranes, nanocomposite membrane with 3h cross-linking time and 90% (w/w) of NCBC-silica content (PCS-3-3) exhibited 1.66×10(-4)cm(3)(STP) cm/cm(2) s cmHg water permeability (P(W)), while 1.35×10(-7) cm(3)(STP) cm/cm(2) s cmHg ethanol permeability (P(EtOH)) of developed membrane and 1231 PV selectivity factor at 30 °C for separating water from 90% (w/w) ethanol mixture. Copyright © 2010 Elsevier Inc. All rights reserved.

Early changes in coronary artery wall structure detected by microcomputed tomography in experimental hypercholesterolemia.

PubMed

Zhu, Xiang-Yang; Bentley, Michael D; Chade, Alejandro R; Ritman, Erik L; Lerman, Amir; Lerman, Lilach O

2007-09-01

Changes in the structure of the artery wall commence shortly after exposure to cardiovascular risk factors, such as hypercholesterolemia (HC), but may be difficult to detect. The ability to study vascular wall structure could be helpful in evaluation of the factors that instigate atherosclerosis and its pathomechanisms. The present study tested the hypothesis that early morphological changes in coronary arteries of hypercholesterolemic (HC) pigs can be detected using the novel X-ray contrast agent OsO(4) and three-dimensional micro-computed tomography (CT). Two groups of pigs were studied after they were fed a normal or an HC (2% cholesterol) diet for 12 wk. Hearts were harvested, coronary arteries were injected with 1% OsO(4) solution, and cardiac samples (6-mum-thick) were scanned by micro-CT. Layers of the epicardial coronary artery wall, early lesions, and perivascular OsO(4) accumulation were determined. Leakage of OsO(4) from myocardial microvessels was used to assess vascular permeability, which was correlated with immunoreactivity of vascular endothelial growth factor in corresponding histological cross sections. OsO(4) enhanced the visualization of coronary artery wall layers and facilitated detection of early lesions in HC in longitudinal tomographic sections of vascular segments. Increased density of perivascular OsO(4) in HC was correlated with increased vascular endothelial growth factor expression and suggested increased microvascular permeability. The use of OsO(4) as a contrast agent in micro-CT allows three-dimensional visualization of coronary artery wall structure, early lesion formation, and changes in vascular permeability. Therefore, this technique can be a useful tool in atherosclerosis research.

Structural control on geothermal circulation in the Cerro Tuzgle-Tocomar geothermal volcanic area (Puna plateau, Argentina)

NASA Astrophysics Data System (ADS)

Giordano, Guido; Pinton, Annamaria; Cianfarra, Paola; Baez, Walter; Chiodi, Agostina; Viramonte, José; Norini, Gianluca; Groppelli, Gianluca

2013-01-01

The reconstruction of the stratigraphical-structural framework and the hydrogeology of geothermal areas is fundamental for understanding the relationships between cap rocks, reservoir and circulation of geothermal fluids and for planning the exploitation of the field. The Cerro Tuzgle-Tocomar geothermal volcanic area (Puna plateau, Central Andes, NW Argentina) has a high geothermal potential. It is crossed by the active NW-SE trans-Andean tectonic lineament known as the Calama-Olacapato-Toro (COT) fault system, which favours a high secondary permeability testified by the presence of numerous springs. This study presents new stratigraphic and hydrogeological data on the geothermal field, together with the analysis from remote sensed image analysis of morphostructural evidences associated with the structural framework and active tectonics. Our data suggest that the main geothermal reservoir is located within or below the Pre-Palaeozoic-Ordovician basement units, characterised by unevenly distributed secondary permeability. The reservoir is recharged by infiltration in the ridges above 4500 m a.s.l., where basement rocks are in outcrop. Below 4500 m a.s.l., the reservoir is covered by the low permeable Miocene-Quaternary units that allow a poor circulation of shallow groundwater. Geothermal fluids upwell in areas with more intense fracturing, especially where main regional structures, particularly NW-SE COT-parallel lineaments, intersect with secondary structures, such as at the Tocomar field. Away from the main tectonic features, such as at the Cerro Tuzgle field, the less developed network of faults and fractures allows only a moderate upwelling of geothermal fluids and a mixing between hot and shallow cold waters. The integration of field-based and remote-sensing analyses at the Cerro Tuzgle-Tocomar area proved to be effective in approaching the prospection of remote geothermal fields, and in defining the conceptual model for geothermal circulation.

Permeability study of cancellous bone and its idealised structures.

PubMed

Syahrom, Ardiyansyah; Abdul Kadir, Mohammed Rafiq; Harun, Muhamad Nor; Öchsner, Andreas

2015-01-01

Artificial bone is a suitable alternative to autografts and allografts, however their use is still limited. Though there were numerous reports on their structural properties, permeability studies of artificial bones were comparably scarce. This study focused on the development of idealised, structured models of artificial cancellous bone and compared their permeability values with bone surface area and porosity. Cancellous bones from fresh bovine femur were extracted and cleaned following an established protocol. The samples were scanned using micro-computed tomography (μCT) and three-dimensional models of the cancellous bones were reconstructed for morphology study. Seven idealised and structured cancellous bone models were then developed and fabricated via rapid prototyping technique. A test-rig was developed and permeability tests were performed on the artificial and real cancellous bones. The results showed a linear correlation between the permeability and the porosity as well as the bone surface area. The plate-like idealised structure showed a similar value of permeability to the real cancellous bones. Copyright © 2014 IPEM. Published by Elsevier Ltd. All rights reserved.

Blood-brain barrier permeation and efflux exclusion of anticholinergics used in the treatment of overactive bladder.

PubMed

Chancellor, Michael B; Staskin, David R; Kay, Gary G; Sandage, Bobby W; Oefelein, Michael G; Tsao, Jack W

2012-04-01

Overactive bladder (OAB) is a common condition, particularly in the elderly. Anticholinergic agents are the mainstay of pharmacological treatment of OAB; however, many anticholinergics can cross the blood-brain barrier (BBB) and may cause central nervous system (CNS) effects, including cognitive deficits, which can be especially detrimental in older patients. Many anticholinergics have the potential to cause adverse CNS effects due to muscarinic (M(1)) receptor binding in the brain. Of note, permeability of the BBB increases with age and can also be affected by trauma, stress, and some diseases and medications. Passive crossing of a molecule across the BBB into the brain is dependent upon its physicochemical properties. Molecular characteristics that hinder passive BBB penetration include a large molecular size, positive or negative ionic charge at physiological pH, and a hydrophilic structure. Active transport across the BBB is dependent upon protein-mediated transporter systems, such as that of permeability-glycoprotein (P-gp), which occurs only for P-gp substrates, such as trospium chloride, darifenacin and fesoterodine. Reliance on active transport can be problematic since genetic polymorphisms of P-gp exist, and many commonly used drugs and even some foods are P-gp inhibitors or are substrates themselves and, due to competition, can reduce the amount of the drug that is actively transported out of the CNS. Therefore, for drugs that are preferred not to cross into the CNS, such as potent anticholinergics intended for the bladder, it is optimal to have minimal passive crossing of the BBB, although it may also be beneficial for the drug to be a substrate for an active efflux transport system. Anticholinergics demonstrate different propensities to cross the BBB. Darifenacin, fesoterodine and trospium chloride are substrates for P-gp and, therefore, are actively transported away from the brain. In addition, trospium chloride has not been detected in cerebrospinal fluid assays and does not appear to have significant CNS penetration. This article reviews the properties of anticholinergics that affect BBB penetration and active transport out of the CNS, discusses issues of increased BBB permeability in patients with OAB, and examines the clinical implications of BBB penetration on adverse events associated with anticholinergics.

Quantitative structure-permeability relationships at various pH values for acidic and basic drugs and drug-like compounds.

PubMed

Oja, M; Maran, U

2015-01-01

Absorption in gastrointestinal tract compartments varies and is largely influenced by pH. Therefore, considering pH in studies and analyses of membrane permeability provides an opportunity to gain a better understanding of the behaviour of compounds and to obtain good permeability estimates for prediction purposes. This study concentrates on relationships between the chemical structure and membrane permeability of acidic and basic drugs and drug-like compounds. The membrane permeability of 36 acidic and 61 basic compounds was measured using the parallel artificial membrane permeability assay (PAMPA) at pH 3, 5, 7.4 and 9. Descriptive and/or predictive single-parameter quantitative structure-permeability relationships were derived for all pH values. For acidic compounds, membrane permeability is mainly influenced by hydrogen bond donor properties, as revealed by models with r(2) > 0.8 for pH 3 and pH 5. For basic compounds, the best (r(2) > 0.7) structure-permeability relationships are obtained with the octanol-water distribution coefficient for pH 7.4 and pH 9, indicating the importance of partition properties. In addition to the validation set, the prediction quality of the developed models was tested with folic acid and astemizole, showing good matches between experimental and calculated membrane permeabilities at key pHs. Selected QSAR models are available at the QsarDB repository ( http://dx.doi.org/10.15152/QDB.166 ).

Structural and conformational determinants of macrocycle cell permeability.

PubMed

Over, Björn; Matsson, Pär; Tyrchan, Christian; Artursson, Per; Doak, Bradley C; Foley, Michael A; Hilgendorf, Constanze; Johnston, Stephen E; Lee, Maurice D; Lewis, Richard J; McCarren, Patrick; Muncipinto, Giovanni; Norinder, Ulf; Perry, Matthew W D; Duvall, Jeremy R; Kihlberg, Jan

2016-12-01

Macrocycles are of increasing interest as chemical probes and drugs for intractable targets like protein-protein interactions, but the determinants of their cell permeability and oral absorption are poorly understood. To enable rational design of cell-permeable macrocycles, we generated an extensive data set under consistent experimental conditions for more than 200 non-peptidic, de novo-designed macrocycles from the Broad Institute's diversity-oriented screening collection. This revealed how specific functional groups, substituents and molecular properties impact cell permeability. Analysis of energy-minimized structures for stereo- and regioisomeric sets provided fundamental insight into how dynamic, intramolecular interactions in the 3D conformations of macrocycles may be linked to physicochemical properties and permeability. Combined use of quantitative structure-permeability modeling and the procedure for conformational analysis now, for the first time, provides chemists with a rational approach to design cell-permeable non-peptidic macrocycles with potential for oral absorption.

Altered Blood-Brain Barrier Permeability in Patients With Systemic Lupus Erythematosus: A Novel Imaging Approach.

PubMed

Gulati, Gaurav; Jones, Jordan T; Lee, Gregory; Altaye, Mekibib; Beebe, Dean W; Meyers-Eaton, Jamie; Wiley, Kasha; Brunner, Hermine I; DiFrancesco, Mark W

2017-02-01

To evaluate a safe, noninvasive magnetic resonance imaging (MRI) method to measure regional blood-brain barrier integrity and investigate its relationship with neurocognitive function and regional gray matter volume in juvenile-onset systemic lupus erythematosus (SLE). In this cross-sectional, case-control study, capillary permeability was measured as a marker of blood-brain barrier integrity in juvenile SLE patients and matched healthy controls, using a combination of arterial spin labeling and diffusion-weighted brain MRI. Regional gray matter volume was measured by voxel-based morphometry. Correlation analysis was done to investigate the relationship between regional capillary permeability and regional gray matter volume. Formal neurocognitive testing was completed (measuring attention, visuoconstructional ability, working memory, and psychomotor speed), and scores were regressed against regional blood-brain barrier integrity among juvenile SLE patients. Formal cognitive testing confirmed normal cognitive ability in all juvenile SLE subjects (n = 11) included in the analysis. Regional capillary permeability was negatively associated (P = 0.026) with neurocognitive performance concerning psychomotor speed in the juvenile SLE cohort. Compared with controls (n = 11), juvenile SLE patients had significantly greater capillary permeability involving Brodmann's areas 19, 28, 36, and 37 and caudate structures (P < 0.05 for all). There is imaging evidence of increased regional capillary permeability in juvenile SLE patients with normal cognitive performance using a novel noninvasive MRI technique. These blood-brain barrier outcomes appear consistent with functional neuronal network alterations and gray matter volume loss previously observed in juvenile SLE patients with overt neurocognitive deficits, supporting the notion that blood-brain barrier integrity loss precedes the loss of cognitive ability in juvenile SLE. Longitudinal studies are needed to confirm the findings of this pilot study. © 2016, American College of Rheumatology.

Changes in sapwood permeability and anatomy with tree age and height in the broad-leaved evergreen species Eucalyptus regnans.

PubMed

England, Jacqueline R; Attiwill, Peter M

2007-08-01

Increases in plant size and structural complexity with increasing age have important implications for water flow through trees. Water supply to the crown is influenced by both the cross-sectional area and the permeability of sapwood. It has been hypothesized that hydraulic conductivity within sapwood increases with age. We investigated changes in sapwood permeability (k) and anatomy with tree age and height in the broad-leaved evergreen species Eucalyptus regnans F. Muell. Sapwood was sampled at breast height from trees ranging from 8 to 240 years old, and at three height positions on the main stem of 8-year-old trees. Variation in k was not significant among sampling height positions in young trees. However, k at breast height increased with tree age. This was related to increases in both vessel frequency and vessel diameter, resulting in a greater proportion of sapwood being occupied by vessel lumina. Sapwood hydraulic conductivity (the product of k and sapwood area) also increased with increasing tree age. However, at the stand level, there was a decrease in forest sapwood hydraulic conductivity with increasing stand age, because of a decrease in the number of trees per hectare. Across all ages, there were significant relationships between k and anatomy, with individual anatomical characteristics explaining 33-62% of the variation in k. There was also strong agreement between measured k and permeability predicted by the Hagen-Poiseuille equation. The results support the hypothesis of an increase in sapwood permeability at breast height with age. Further measurements are required to confirm this result at other height positions in older trees. The significance of tree-level changes in sapwood permeability for stand-level water relations is discussed.

Angiopoietin-2 mediates blood-brain barrier impairment and colonization of triple-negative breast cancer cells in brain.

PubMed

Avraham, Hava Karsenty; Jiang, Shuxian; Fu, Yigong; Nakshatri, Harikrishna; Ovadia, Haim; Avraham, Shalom

2014-02-01

Although the incidence of breast cancer metastasis (BCM) in brain has increased significantly in triple-negative breast cancer (TNBC), the mechanisms remain elusive. Using in vivo mouse models for BCM in brain, we observed that TNBC cells crossed the blood-brain barrier (BBB), lodged in the brain microvasculature and remained adjacent to brain microvascular endothelial cells (BMECs). Breaching of the BBB in vivo by TNBCs resulted in increased BBB permeability and changes in ZO-1 and claudin-5 tight junction (TJ) protein structures. Angiopoietin-2 expression was elevated in BMECs and was correlated with BBB disruption. Secreted Ang-2 impaired TJ structures and increased BBB permeability. Treatment of mice with the neutralizing Ang-2 peptibody trebananib prevented changes in the BBB integrity and BMEC destabilization, resulting in inhibition of TNBC colonization in brain. Thus, Ang-2 is involved in initial steps of brain metastasis cascade, and inhibitors for Ang-2 may serve as potential therapeutics for brain metastasis. Copyright © 2013 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

Is vertebrate mortality correlated to potential permeability by underpasses along low-traffic roads?

PubMed

Delgado, Juan D; Morelli, Federico; Arroyo, Natalia L; Durán, Jorge; Rodríguez, Alexandra; Rosal, Antonio; Palenzuela, María Del Valle; Rodríguez, Jesús D G P

2018-09-01

Road permeability to animal movements depends among several factors on structures which, integrated in the road design, operate as safe conducts to mitigate vehicle collision and barrier effects. There is abundant evidence that wildlife makes use of such structures as safe passages to cross roads. We analyzed the spatial relationship between road drainage elements (N = 253; mostly culverts) as potential faunal underpasses, and mortality due to vehicle collisions in two seasons and on four relatively low-traffic roads (<5000 cars/day) traversing oak rangelands of western Andalusia (S Spain). Focusing on amphibians, reptiles and mammals, we recorded and located casualties (N = 238 individuals, 35 species) along these roads, identifying and characterizing all potential underpasses. Overall frequencies of casualties and spatial distribution were highly variable both within and among these roads. We obtained an estimation of potential permeability for the different roads. We detected, located and described a wide supply and a very variable pattern of drainage culverts and other underpasses, with differences among roads in passage attributes potentially affecting permeability for wildlife, such as spatial arrangement, number, density (frequency or concentration of passages) and dimensions. We used Mantel tests to assess spatial congruence of passages and road-killed animals. We applied generalized linear mixed models fitted by maximum likelihood through Akaike Information Criterion to explain the variation in the distance of the 238 casualties to the nearest underpasses, with road transect and season as random factors, and traffic intensity, speed and vertebrate class as fixed effects. Both road-killed animals and underpass distribution followed aggregated patterns, and casualties were not significantly related to underpasses along any of the 4 roads. There were no differences in distance of casualties to the nearest underpass for the three vertebrate classes. Although existing underpasses were abundant, we could not correlate potential permeability with reduced mortality along these roads, and other factors potentially affecting roadkill aggregations should be evaluated along with permeability assessment. Mitigation of road-caused mortality can still be greatly improved for these roads, through measures of reconditioning and proper management of existing underpasses, aiming to maximize road permeability and reducing major impacts upon animal populations of Andalusian rangelands. Copyright © 2018 Elsevier Ltd. All rights reserved.

Semi-interpenetrating polymer network proton exchange membranes with narrow and well-connected hydrophilic channels

NASA Astrophysics Data System (ADS)

Fang, Chunliu; Toh, Xin Ni; Yao, Qiaofeng; Julius, David; Hong, Liang; Lee, Jim Yang

2013-03-01

Four series of semi-interpenetrating polymer network (SIPN) membranes are fabricated by thermally cross-linking aminated BPPO (brominated poly(2,6-dimethyl-1,4-phenylene oxide)) with different epoxide cross-linkers in the presence of sulfonated PPO (SPPO). The cross-link structure and hydrophobicity are found to impact the membrane morphology strongly - smaller and more hydrophobic cross-links form narrow and well-connected hydrophilic channels whereas bulky and less hydrophobic cross-links form wide but less-connected hydrophilic channels. The membranes of the former can support facile proton transport and suppress methanol crossover to result in higher proton conductivity and lower methanol permeability than the membranes of the latter. The membranes are also fabricated into membrane electrode assemblies (MEAs) and tested in single-stack direct methanol fuel cells (DMFCs). It is found that some of these SIPN membranes can surpass Nafion® 117 in maximum power density, demonstrating their potential as a proton exchange membrane (PEM) for the DMFCs.

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

Zhu, Lingxiang; Omid, Maryam; Lin, Haiqing

Cross-linking has been widely utilized to modify polyimide nanostructures for membrane gas separations, such as increasing size sieving ability and diffusivity selectivity for H2/CO2 and CO2/CH4 separation, and improving resistance to plasticization derived from CO2 and heavy hydrocarbons for CO2/CH4 and C3H6/C3H8 separations. However, there is a lack of fundamental understanding of the relationship between cross linked structure and membrane gas separation properties. This chapter critically reviews the effect of cross linking on polymer physical properties (such as glass transition temperature, Tg), and current strategies adopted to cross link polyimides for membrane gas separation. The information is synthesized to elucidatemore » the effect of cross linking on Tg and cross linking density in polyimides, which is then used to interpret the changes of gas permeability and selectivity. The benefits of cross linking in improving gas separation properties are also illustrated in Robeson’s upper bound plots for H2/CO2, CO2/CH4 and C3H6/C3H8 separation.« less

On the effects of subsurface parameters on evaporite dissolution (Switzerland)

NASA Astrophysics Data System (ADS)

Zidane, Ali; Zechner, Eric; Huggenberger, Peter; Younes, Anis

2014-05-01

Uncontrolled subsurface evaporite dissolution could lead to hazards such as land subsidence. Observed subsidences in a study area of Northwestern Switzerland were mainly due to subsurface dissolution (subrosion) of evaporites such as halite and gypsum. A set of 2D density driven flow simulations were evaluated along 1000 m long and 150 m deep 2D cross sections within the study area that is characterized by tectonic horst and graben structures. The simulations were conducted to study the effect of the different subsurface parameters that could affect the dissolution process. The heterogeneity of normal faults and its impact on the dissolution of evaporites is studied by considering several permeable faults that include non-permeable areas. The mixed finite element method (MFE) is used to solve the flow equation, coupled with the multipoint flux approximation (MPFA) and the discontinuous Galerkin method (DG) to solve the diffusion and the advection parts of the transport equation.

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

Hong, Tao; Niu, Zhenbin; Hu, Xunxiang

The development of high performance materials for CO 2 separation and capture will significantly contribute to a solution for climate change. In this work, (bicycloheptenyl) ethyl terminated polydimethylsiloxane (PDMSPNB) membranes with varied cross-link densities were synthesized via ring-opening metathesis polymerization. The developed polymer membranes show higher permeability and better selectivity than those of conventional cross-linked PDMS membrane. The achieved performance (CO 2 permeability ~ 6800 Barrer and CO 2/N 2 selectivity ~ 14) is very promising for practical applications. The key to achieving this high performance is the use of an in-situ cross-linking method of the difunctional PDMS macromonomers, whichmore » provides lightly cross-linked membranes. By combining positron annihilation lifetime spectroscopy, broadband dielectric spectroscopy and gas solubility measurements, we have elucidated the key parameters necessary for achieving their excellent performance.« less

Ignition technique for an in situ oil shale retort

DOEpatents

Cha, Chang Y.

1983-01-01

A generally flat combustion zone is formed across the entire horizontal cross-section of a fragmented permeable mass of formation particles formed in an in situ oil shale retort. The flat combustion zone is formed by either sequentially igniting regions of the surface of the fragmented permeable mass at successively lower elevations or by igniting the entire surface of the fragmented permeable mass and controlling the rate of advance of various portions of the combustion zone.

Effect of cross-link density on carbon dioxide separation in polydimethylsiloxane-norbornene membranes

DOE PAGES

Hong, Tao; Niu, Zhenbin; Hu, Xunxiang; ...

2015-10-20

The development of high performance materials for CO 2 separation and capture will significantly contribute to a solution for climate change. In this work, (bicycloheptenyl) ethyl terminated polydimethylsiloxane (PDMSPNB) membranes with varied cross-link densities were synthesized via ring-opening metathesis polymerization. The developed polymer membranes show higher permeability and better selectivity than those of conventional cross-linked PDMS membrane. The achieved performance (CO 2 permeability ~ 6800 Barrer and CO 2/N 2 selectivity ~ 14) is very promising for practical applications. The key to achieving this high performance is the use of an in-situ cross-linking method of the difunctional PDMS macromonomers, whichmore » provides lightly cross-linked membranes. By combining positron annihilation lifetime spectroscopy, broadband dielectric spectroscopy and gas solubility measurements, we have elucidated the key parameters necessary for achieving their excellent performance.« less

Influence of fiber packing structure on permeability

NASA Technical Reports Server (NTRS)

Cai, Zhong; Berdichevsky, Alexander L.

1993-01-01

The study on the permeability of an aligned fiber bundle is the key building block in modeling the permeability of advanced woven and braided preforms. Available results on the permeability of fiber bundles in the literature show that a substantial difference exists between numerical and analytical calculations on idealized fiber packing structures, such as square and hexagonal packing, and experimental measurements on practical fiber bundles. The present study focuses on the variation of the permeability of a fiber bundle under practical process conditions. Fiber bundles are considered as containing openings and fiber clusters within the bundle. Numerical simulations on the influence of various openings on the permeability were conducted. Idealized packing structures are used, but with introduced openings distributed in different patterns. Both longitudinal and transverse flow are considered. The results show that openings within the fiber bundle have substantial effect on the permeability. In the longitudinal flow case, the openings become the dominant flow path. In the transverse flow case, the fiber clusters reduce the gap sizes among fibers. Therefore the permeability is greatly influenced by these openings and clusters, respectively. In addition to the porosity or fiber volume fraction, which is commonly used in the permeability expression, another fiber bundle status parameter, the ultimate fiber volume fraction, is introduced to capture the disturbance within a fiber bundle.

Stratigraphy and structure of coalbed methane reservoirs in the United States: an overview

USGS Publications Warehouse

Pashin, J.C.

1998-01-01

Stratigraphy and geologic structure determine the shape, continuity and permeability of coal and are therefore critical considerations for designing exploration and production strategies for coalbed methane. Coal in the United states is dominantly of Pennsylvanian, Cretaceous and Tertiary age, and to date, more than 90% of the coalbed methane produced is from Pennsylvanian and cretaceous strata of the Black Warrior and San Juan Basins. Investigations of these basins establish that sequence stratigraphy is a promising approach for regional characterization of coalbed methane reservoirs. Local stratigraphic variation within these strata is the product of sedimentologic and tectonic processes and is a consideration for selecting completion zones. Coalbed methane production in the United States is mainly from foreland and intermontane basins containing diverse compression and extensional structures. Balanced structural models can be used to construct and validate cross sections as well as to quantify layer-parallel strain and predict the distribution of fractures. Folds and faults influence gas and water production in diverse ways. However, interwell heterogeneity related to fractures and shear structures makes the performance of individual wells difficult to predict.Stratigraphy and geologic structure determine the shape, continuity and permeability of coal and are therefore critical considerations for designing exploration and production strategies for coalbed methane. Coal in the United States is dominantly of Pennsylvanian, Cretaceous and Tertiary age, and to date, more than 90% of the coalbed methane produced is from Pennsylvanian and Cretaceous strata of the Black Warrior and San Juan Basins. Investigations of these basins establish that sequence stratigraphy is a promising approach for regional characterization of coalbed methane reservoirs. Local stratigraphic variation within these strata is the product of sedimentologic and tectonic processes and is a consideration for selecting completion zones. Coalbed methane production in the United States is mainly from foreland and intermontane basins containing diverse compressional and extensional structures. Balanced structural models can be used to construct and validate cross sections as well as to quantify layer-parallel strain and predict the distribution of fractures. Folds and faults influence gas and water production in diverse ways. However, interwell heterogeneity related to fractures and shear structures makes the performance of individual wells difficult to predict.

Effect of permeable flow on cyclic layering in solidifying magma bodies: Insights from an analog experiment of diffusion-precipitation systems

NASA Astrophysics Data System (ADS)

Toramaru, A.; Yamauchi, S.

2012-04-01

Characteristic structures such as rhythmic layering, cress cumulate, cross bedding, perpendicular feldspar rock etc, are commonly observed in layered intrusion or shallow magmatic intrusions. These structures result from complex processes including thermal and compositional diffusions, crystallization, crystal settling, convection and interaction among three phases (crystals, bubble, melt). In order to understand how the differentiation proceeds in solidifying magma bodies from each characteristic structure together with chemical signatures, it is necessary to evaluate the relative importance among these elemental processes on structures. As an attempt to evaluate the effect of advection on a diffusion-related structure, we carried out an analog experiment of Liesegang system using lead-iodide (PbI2) crystallization in agar media which have been normally used to prohibit convection. In the ordinary Liesegang band formation experiments including only diffusion and crystallization kinetics without any advection and convection, the precipitation bands develop with regular spacing following a geometric progression due to two-component diffusion and reaction with supersaturation. This type of banding structure has been advocated as the same type of cyclic layering or vesicle layering (a sort of rhythmic layering) in dykes or sills. In order to see the effect of one-directional advection on Liesegang band, we apply the electric field (5 V to 25 V for a distance 15 cm) along the concentration gradient in agar media, thereby counteracting flows of lead anion Pb2+ and iodide ion I- are driven at constant velocities. The flows of anions and ions are equivalent to the permeable flows in porous media of crystal mush. The resultant precipitation structures exhibit very curious banding structure in which band spacings do not change with distance, are nearly constant and quite narrow, depending on the voltage, unlike those in ordinary Liesegang bands in which band spacings increase with distance following geometric progression. Further interestingly each band consists of a lot of very tiny irregular-shaped crystal aggregates. From experimental results and scaling arguments, with regard to the effect of one directional permeable flow on band spacing of cyclic layering, we propose a hypothesis of constant Peclet number that Peclet number (ratio of flow velocity to diffusive velocity) is nearly unity. By applying the hypothesis to natural examples, we can estimate a value of permeable flow velocity of interstitial melts in differentiating magma bodies from values of a band spacing and diffusivity data.

Electrochemical and spectroscopic characterization of surface sol-gel processes.

PubMed

Chen, Xiaohong; Wilson, George S

2004-09-28

(3-Mercaptopropyl)trimethoxysilane (MTS) forms a unique film on a platinum substrate by self-assembly and sol-gel cross-linking. The gelating and drying states of the self-assembled MTS sol-gel films were probed by use of electrochemical and spectroscopic methods. The thiol moiety was the only active group within the sol-gel network. Gold nanoparticles were employed to detect the availability of the thiol group and their interaction further indicated the physicochemical states of the sol-gel inner structure. It was found that the thiol groups in the open porous MTS aerogel matrix were accessible to the gold nanoparticles while thiol groups in the compact MTS xerogel network were not accessible to the gold nanoparticles. The characteristics of the sol-gel matrix change with time because of its own irreversible gelating and drying process. The present work provides direct evidence of gold nanoparticle binding with thiol groups within the sol-gel structures and explains the different permeability of "aerogel" and "xerogel" films of MTS on the basis of electrochemical and spectroscopic results. Two endogenous species, hydrogen peroxide and ascorbic acid, were used to test the permeability of the self-assembled sol-gel film in different states. The MTS xerogel film on the platinum electrode was extremely selective against ascorbic acid while maintaining high sensitivity to hydrogen peroxide in contrast to the relatively high permeability of ascorbic acid in the MTS aerogel film. This study showed the potential of the MTS sol-gel film as a nanoporous material in biosensor development.

In silico modeling on ADME properties of natural products: Classification models for blood-brain barrier permeability, its application to traditional Chinese medicine and in vitro experimental validation.

PubMed

Zhang, Xiuqing; Liu, Ting; Fan, Xiaohui; Ai, Ni

2017-08-01

In silico modeling of blood-brain barrier (BBB) permeability plays an important role in early discovery of central nervous system (CNS) drugs due to its high-throughput and cost-effectiveness. Natural products (NP) have demonstrated considerable therapeutic efficacy against several CNS diseases. However, BBB permeation property of NP is scarcely evaluated both experimentally and computationally. It is well accepted that significant difference in chemical spaces exists between NP and synthetic drugs, which calls into doubt on suitability of available synthetic chemical based BBB permeability models for the evaluation of NP. Herein poor discriminative performance on BBB permeability of NP are first confirmed using internal constructed and previously published drug-derived computational models, which warrants the need for NP-oriented modeling. Then a quantitative structure-property relationship (QSPR) study on a NP dataset was carried out using four different machine learning methods including support vector machine, random forest, Naïve Bayes and probabilistic neural network with 67 selected features. The final consensus model was obtained with approximate 90% overall accuracy for the cross-validation study, which is further taken to predict passive BBB permeability of a large dataset consisting of over 10,000 compounds from traditional Chinese medicine (TCM). For 32 selected TCM molecules, their predicted BBB permeability were evaluated by in vitro parallel artificial membrane permeability assay and overall accuracy for in vitro experimental validation is around 81%. Interestingly, our in silico model successfully predicted different BBB permeation potentials of parent molecules and their known in vivo metabolites. Finally, we found that the lipophilicity, the number of hydrogen bonds and molecular polarity were important molecular determinants for BBB permeability of NP. Our results suggest that the consensus model proposed in current work is a reliable tool for prioritizing potential CNS active NP across the BBB, which would accelerate their development and provide more understanding on their mechanisms, especially those with pharmacologically active metabolites. Copyright © 2017 Elsevier Inc. All rights reserved.

Permeability of nanonet structures constructed on the basis of carbon tubes

NASA Astrophysics Data System (ADS)

Bubenchikov, M. A.; Nikipelova, T. I.; Tsyrenova, V. B.; Chelnokova, A. S.

2017-11-01

An approximate integration of a potential of paired molecular interactions over the circumferential coordinate is used to find the potential of the interaction between a molecule and an infinite carbon nanotube (CNT). Based on the obtained energy of interaction between the tube and the molecules, local effective radii of the investigated carbon structures with respect to the molecules of the separated gas mixture are found. This makes it possible to calculate permeability of a single-layer, along with a two-layer CNT packing. The conducted research allowed calculating permeability of a nanonet structure as permeability of a two-layer packing of carbon nanotubes for the first time.

Intermolecular ionic cross-linked sulfonated poly(ether ether ketone) membranes containing diazafluorene for direct methanol fuel cell applications

NASA Astrophysics Data System (ADS)

Liang, Yu; Gong, Chenliang; Qi, Zhigang; Li, Hui; Wu, Zhongying; Zhang, Yakui; Zhang, Shujiang; Li, Yanfeng

2015-06-01

A series of novel ionic cross-linking sulfonated poly(ether ether ketone) (SPEEK) membranes containing the diazafluorene functional group are synthesized to reduce the swelling ratio and methanol permeability for direct methanol fuel cell (DMFC) applications. The ionic cross-linking is realized by the interaction between sulfonic acid groups and pyridyl in diazafluorene. The prepared membranes exhibit good mechanical properties, adequate thermal stability, good oxidative stability, appropriate water uptake and low swelling ratio. Moreover, the ionic cross-linked membranes exhibit lower methanol permeability in the range between 0.56 × 10-7 cm2 s-1 and 1.8 × 10-7 cm2 s-1, which is lower than Nafion 117, and they exhibit higher selectivity than Nafion 117 at 30 °C on the basis of applicable proton conductivity.

Numerical analysis of the hydrogeologic controls in a layered coastal aquifer system, Oahu, Hawaii, USA

USGS Publications Warehouse

Oki, D.S.; Souza, W.R.; Bolke, E.L.; Bauer, G.R.

1998-01-01

The coastal aquifer system of southern Oahu, Hawaii, USA, consists of highly permeable volcanic aquifers overlain by weathered volcanic rocks and interbedded marine and terrestrial sediments of both high and low permeability. The weathered volcanic rocks and sediments are collectively known as caprock, because they impede the free discharge of groundwater from the underlying volcanic aquifers. A cross-sectional groundwater flow and transport model was used to evaluate the hydrogeologic controls on the regional flow system in southwestern Oahu. Controls considered were: (a) overall caprock hydraulic conductivity; and (b) stratigraphic variations of hydraulic conductivity in the caprock. Within the caprock, variations in hydraulic conductivity, caused by stratigraphy or discontinuities of the stratigraphic units, are a major control on the direction of groundwater flow and the distribution of water levels and salinity. Results of cross-sectional modeling confirm the general groundwater flow pattern that would be expected in a layered coastal system. Ground-water flow is: (a) predominantly upward in the low-permeability sedimentary units; and (b) predominantly horizontal in the high-permeability sedimentary units.

Comment on "Analysis of single-layer metamaterial absorber with reflection theory" [J. Appl. Phys. 117, 154906 (2015)

NASA Astrophysics Data System (ADS)

Tung, Nguyen Thanh

2016-03-01

In a recent paper, Xiong et al. [J. Appl. Phys. 117, 154906 (2015)] presented the simulated results of a Jerusalem-cross structure in an attempt to elaborate their proposed reflection theory for metamaterial absorbers. Noting that even at non-resonant frequencies the real part of the permeability shows an over-high average value and its imaginary part drops abruptly from positivity to negativity, we argue that their simulated results are unphysical, resulting from an incomplete understanding of the retrieval procedure.

Fabrication and characterization of poly(propylene fumarate) scaffolds with controlled pore structures using 3-dimensional printing and injection molding.

PubMed

Lee, Kee-Won; Wang, Shanfeng; Lu, Lichun; Jabbari, Esmaiel; Currier, Bradford L; Yaszemski, Michael J

2006-10-01

Poly(propylene fumarate) (PPF) is an injectable, biodegradable polymer that has been used for fabricating preformed scaffolds in tissue engineering applications because of in situ crosslinking characteristics. Aiming for understanding the effects of pore structure parameters on bone tissue ingrowth, 3-dimensional (3D) PPF scaffolds with controlled pore architecture have been produced in this study from computer-aided design (CAD) models. We have created original scaffold models with 3 pore sizes (300, 600, and 900 microm) and randomly closed 0%, 10%, 20%, or 30% of total pores from the original models in 3 planes. PPF scaffolds were fabricated by a series steps involving 3D printing of support/build constructs, dissolving build materials, injecting PPF, and dissolving support materials. To investigate the effects of controlled pore size and interconnectivity on scaffolds, we compared the porosities between the models and PPF scaffolds fabricated thereby, examined pore morphologies in surface and cross-section using scanning electron microscopy, and measured permeability using the falling head conductivity test. The thermal properties of the resulting scaffolds as well as uncrosslinked PPF were determined by differential scanning calorimetry and thermogravimetric analysis. Average pore sizes and pore shapes of PPF scaffolds with 600- and 900-microm pores were similar to those of CAD models, but they depended on directions in those with 300-microm pores. Porosity and permeability of PPF scaffolds decreased as the number of closed pores in original models increased, particularly when the pore size was 300 microm as the result of low porosity and pore occlusion. These results show that 3D printing and injection molding technique can be applied to crosslinkable polymers to fabricate 3D porous scaffolds with controlled pore structures, porosity, and permeability using their CAD models.

Effects of Salinity and Confining Pressure on Hydration-Induced Fracture Propagation and Permeability of Mancos Shale

NASA Astrophysics Data System (ADS)

Zhang, Shifeng; Sheng, James J.

2017-11-01

Low-salinity water imbibition was considered an enhanced recovery method in shale oil/gas reservoirs due to the resulting hydration-induced fractures, as observed at ambient conditions. To study the effect of confining pressure and salinity on hydration-induced fractures, time-elapsed computerized tomography (CT) was used to obtain cross-sectional images of shale cores. Based on the CT data of these cross-sectional images, cut faces parallel to the core axial in the middle of the core and 3D fracture images were also reconstructed. To study the effects of confining pressure and salinity on shale pore fluid flowing, shale permeability was measured with Nitrogen (N2), distilled water, 4% KCl solution, and 8% KCl solution. With confining pressures increased to 2 MPa or more, either in distilled water or in KCl solutions of different salinities, fractures were observed to close instead to propagate at the end of the tests. The intrinsic permeabilities of #1 and #2 Mancos shale cores were 60.0 and 7000 nD, respectively. When tested with distilled water, the permeability of #1 shale sample with 20.0 MPa confining pressure loaded, and #2 shale sample with 2.5 MPa confining pressure loaded, decreased to 0.45 and 15 nD, respectively. Using KCl can partly mitigate shale permeability degradation. Compared to 4% KCl, 8% KCl can decrease more permeability damage. From this point of view, high salinity KCl solution should be required for the water-based fracturing fluid.

Clogging in permeable concrete: A review.

PubMed

Kia, Alalea; Wong, Hong S; Cheeseman, Christopher R

2017-05-15

Permeable concrete (or "pervious concrete" in North America) is used to reduce local flooding in urban areas and is an important sustainable urban drainage system. However, permeable concrete exhibits reduction in permeability due to clogging by particulates, which severely limits service life. This paper reviews the clogging mechanism and current mitigating strategies in order to inform future research needs. The pore structure of permeable concrete and characteristics of flowing particulates influence clogging, which occurs when particles build-up and block connected porosity. Permeable concrete requires regular maintenance by vacuum sweeping and pressure washing, but the effectiveness and viability of these methods is questionable. The potential for clogging is related to the tortuosity of the connected porosity, with greater tortuosity resulting in increased potential for clogging. Research is required to develop permeable concrete that can be poured on-site, which produces a pore structure with significantly reduced tortuosity. Copyright © 2017 Elsevier Ltd. All rights reserved.

Tunable d-Limonene Permeability in Starch-Based Nanocomposite Films Reinforced by Cellulose Nanocrystals.

PubMed

Liu, Siyuan; Li, Xiaoxi; Chen, Ling; Li, Lin; Li, Bing; Zhu, Jie

2018-01-31

In order to control d-limonene permeability, cellulose nanocrystals (CNC) were used to regulate starch-based film multiscale structures. The effect of sphere-like cellulose nanocrystal (CS) and rod-like cellulose nanocrystal (CR) on starch molecular interaction, short-range molecular conformation, crystalline structure, and micro-ordered aggregated region structure were systematically discussed. CNC aspect ratio and content were proved to be independent variables to control d-limonene permeability via film-structure regulation. New hydrogen bonding formation and increased hydroxypropyl starch (HPS) relative crystallinity could be the reason for the lower d-limonene permeability compared with tortuous path model approximation. More hydrogen bonding formation, higher HPS relative crystallinity and larger size of micro-ordered aggregated region in CS0.5 and CR2 could explain the lower d-limonene permeability than CS2 and CR0.5, respectively. This study provided new insight for the control of the flavor release from starch-based films, which favored its application in biodegradable food packaging and flavor encapsulation.

General Platform for Systematic Quantitative Evaluation of Small-Molecule Permeability in Bacteria

PubMed Central

2015-01-01

The chemical features that impact small-molecule permeability across bacterial membranes are poorly understood, and the resulting lack of tools to predict permeability presents a major obstacle to the discovery and development of novel antibiotics. Antibacterials are known to have vastly different structural and physicochemical properties compared to nonantiinfective drugs, as illustrated herein by principal component analysis (PCA). To understand how these properties influence bacterial permeability, we have developed a systematic approach to evaluate the penetration of diverse compounds into bacteria with distinct cellular envelopes. Intracellular compound accumulation is quantitated using LC-MS/MS, then PCA and Pearson pairwise correlations are used to identify structural and physicochemical parameters that correlate with accumulation. An initial study using 10 sulfonyladenosines in Escherichia coli, Bacillus subtilis, and Mycobacterium smegmatis has identified nonobvious correlations between chemical structure and permeability that differ among the various bacteria. Effects of cotreatment with efflux pump inhibitors were also investigated. This sets the stage for use of this platform in larger prospective analyses of diverse chemotypes to identify global relationships between chemical structure and bacterial permeability that would enable the development of predictive tools to accelerate antibiotic drug discovery. PMID:25198656

Estimating dynamic permeability in fractal pore network saturated by Maxwellian fluid

NASA Astrophysics Data System (ADS)

Sun, W.

2017-12-01

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 pore 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 pressure 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 pore network is created by a Voronoi cell filling method. The porosity, i.e., volume ratio between pore/pipe network and the overall cubic, is set as 0.1. The irregular pore network has a fractal structure. The dimension d of the pore 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 pore 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 network. Small-scale network has higher dimension than large-scale networks. The reason is that in larger networks pore and inter-pore connections are so dense that the probability P(r) to have a neighboring pore at distance r decays faster. The proposed model may be used to explain velocity dispersion in unconventional reservoir rocks observed in laboratory.

Effect of temperature on the permeability of gas adsorbed coal under triaxial stress conditions

NASA Astrophysics Data System (ADS)

Li, Xiangchen; Yan, Xiaopeng; Kang, Yili

2018-04-01

The combined effects of gas sorption, stress and temperature play a significant role in the changing behavior of gas permeability in coal seams. The effect of temperature on nitrogen and methane permeability of naturally fractured coal is investigated. Coal permeability, P-wave velocity and axial strain were simultaneously measured under two effective stresses and six different temperatures. The results showed that the behavior of nitrogen and methane permeability presented nonmonotonic changes with increasing temperature. The variation in the P-wave velocity and axial strain showed a good correspondence with coal permeability. A higher effective stress limited the bigger deformation and caused the small change in permeability. Methane adsorption and desorption significantly influence the mechanical properties of coal and play an important role in the variations in coal permeability. The result of coal permeability during a complete stress-strain process showed that the variation in permeability is determined by the evolution of the internal structure. The increase in the temperature of the gas saturated coal causes the complex interaction between matrix swelling, matrix shrinkage and micro-fracture generation, which leads to the complex changes in coal structure and permeability. These results are helpful to understand the gas transport mechanism for exploiting coal methane by heat injection.

The blood-brain barrier: an engineering perspective

PubMed Central

Wong, Andrew D.; Ye, Mao; Levy, Amanda F.; Rothstein, Jeffrey D.; Bergles, Dwight E.; Searson, Peter C.

2013-01-01

It has been more than 100 years since Paul Ehrlich reported that various water-soluble dyes injected into the circulation did not enter the brain. Since Ehrlich's first experiments, only a small number of molecules, such as alcohol and caffeine have been found to cross the blood-brain barrier, and this selective permeability remains the major roadblock to treatment of many central nervous system diseases. At the same time, many central nervous system diseases are associated with disruption of the blood-brain barrier that can lead to changes in permeability, modulation of immune cell transport, and trafficking of pathogens into the brain. Therefore, advances in our understanding of the structure and function of the blood-brain barrier are key to developing effective treatments for a wide range of central nervous system diseases. Over the past 10 years it has become recognized that the blood-brain barrier is a complex, dynamic system that involves biomechanical and biochemical signaling between the vascular system and the brain. Here we reconstruct the structure, function, and transport properties of the blood-brain barrier from an engineering perspective. New insight into the physics of the blood-brain barrier could ultimately lead to clinical advances in the treatment of central nervous system diseases. PMID:24009582

Cracks in the palisade cuticle of soybean seed coats correlate with their permeability to water.

PubMed

Ma, Fengshan; Cholewa, Ewa; Mohamed, Tasneem; Peterson, Carol A; Gijzen, Mark

2004-08-01

Soybean (Glycine max) is among the many legumes that are well known for 'hardseededness'. This feature can be beneficial for long-term seed survival, but is undesirable for the food processing industry. There is substantial disagreement concerning the mechanisms and related structures that control the permeability properties of soybean seed coats. In this work, the structural component that controls water entry into the seed is identified. Six soybean cultivars were tested for their seed coat permeabilities to water. To identify the structural feature(s) that may contribute to the determination of these permeabilities, fluorescent tracer dyes, and light and electron microscopic techniques were used. The cultivar 'Tachanagaha' has the most permeable seed coat, 'OX 951' the least permeable seed coat, and the permeabilities of the rest ('Harovinton', 'Williams', 'Clark L 67-3469', and 'Harosoy 63') are intermediate. All seeds have surface deposits, depressions, a light line, and a cuticle about 0.2 microm thick overlaying the palisade layer. In permeable cultivars the cuticle tends to break, whereas in impermeable seeds of 'OX 951' it remains intact. In the case of permeable seed coats, the majority of the cracks are from 1 to 5 micro m wide and from 20 to 200 micro m long, and occur more frequently on the dorsal side than in other regions of the seed coat, a position that correlates with the site of initial water uptake. The cuticle of the palisade layer is the key factor that determines the permeability property of a soybean seed coat. The cuticle of a permeable seed coat is mechanically weak and develops small cracks through which water can pass. The cuticle of an impermeable seed coat is mechanically strong and does not crack under normal circumstances.

Predicting A Drug'S Membrane Permeability: Evolution of a Computational Model Validated with in Vitro Permeability Assay Data

DOE PAGES

Carpenter, Timothy S.; McNerney, M. Windy; Be, Nicholas A.; ...

2016-02-16

Membrane permeability is a key property to consider in drug design, especially when the drugs in question need to cross the blood-brain barrier (BBB). A comprehensive in vivo assessment of the BBB permeability of a drug takes considerable time and financial resources. A current, simplified in vitro model to investigate drug permeability is a Parallel Artificial Membrane Permeability Assay (PAMPA) that generally provides higher throughput and initial quantification of a drug's passive permeability. Computational methods can also be used to predict drug permeability. Our methods are highly advantageous as they do not require the synthesis of the desired drug, andmore » can be implemented rapidly using high-performance computing. In this study, we have used umbrella sampling Molecular Dynamics (MD) methods to assess the passive permeability of a range of compounds through a lipid bilayer. Furthermore, the permeability of these compounds was comprehensively quantified using the PAMPA assay to calibrate and validate the MD methodology. And after demonstrating a firm correlation between the two approaches, we then implemented our MD method to quantitatively predict the most permeable potential drug from a series of potential scaffolds. This permeability was then confirmed by the in vitro PAMPA methodology. Therefore, in this work we have illustrated the potential that these computational methods hold as useful tools to help predict a drug's permeability in a faster and more cost-effective manner. Release number: LLNL-ABS-677757.« less

Predicting A Drug'S Membrane Permeability: Evolution of a Computational Model Validated with in Vitro Permeability Assay Data

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

Carpenter, Timothy S.; McNerney, M. Windy; Be, Nicholas A.

Membrane permeability is a key property to consider in drug design, especially when the drugs in question need to cross the blood-brain barrier (BBB). A comprehensive in vivo assessment of the BBB permeability of a drug takes considerable time and financial resources. A current, simplified in vitro model to investigate drug permeability is a Parallel Artificial Membrane Permeability Assay (PAMPA) that generally provides higher throughput and initial quantification of a drug's passive permeability. Computational methods can also be used to predict drug permeability. Our methods are highly advantageous as they do not require the synthesis of the desired drug, andmore » can be implemented rapidly using high-performance computing. In this study, we have used umbrella sampling Molecular Dynamics (MD) methods to assess the passive permeability of a range of compounds through a lipid bilayer. Furthermore, the permeability of these compounds was comprehensively quantified using the PAMPA assay to calibrate and validate the MD methodology. And after demonstrating a firm correlation between the two approaches, we then implemented our MD method to quantitatively predict the most permeable potential drug from a series of potential scaffolds. This permeability was then confirmed by the in vitro PAMPA methodology. Therefore, in this work we have illustrated the potential that these computational methods hold as useful tools to help predict a drug's permeability in a faster and more cost-effective manner. Release number: LLNL-ABS-677757.« less

Grain-size dynamics beneath mid-ocean ridges: Implications for permeability and melt extraction.

PubMed

Turner, Andrew J; Katz, Richard F; Behn, Mark D

2015-03-01

Grain size is an important control on mantle viscosity and permeability, but is difficult or impossible to measure in situ. We construct a two-dimensional, single phase model for the steady state mean grain size beneath a mid-ocean ridge. The mantle rheology is modeled as a composite of diffusion creep, dislocation creep, dislocation accommodated grain boundary sliding, and a plastic stress limiter. The mean grain size is calculated by the paleowattmeter relationship of Austin and Evans (2007). We investigate the sensitivity of our model to global variations in grain growth exponent, potential temperature, spreading-rate, and mantle hydration. We interpret the mean grain-size field in terms of its permeability to melt transport. The permeability structure due to mean grain size may be approximated as a high permeability region beneath a low permeability region. The transition between high and low permeability regions occurs across a boundary that is steeply inclined toward the ridge axis. We hypothesize that such a permeability structure generated from the variability of the mean grain size may focus melt toward the ridge axis, analogous to Sparks and Parmentier (1991)-type focusing. This focusing may, in turn, constrain the region where significant melt fractions are observed by seismic or magnetotelluric surveys. This interpretation of melt focusing via the grain-size permeability structure is consistent with MT observation of the asthenosphere beneath the East Pacific Rise. The grain-size field beneath MORs can vary over orders of magnitude The grain-size field affects the rheology and permeability of the asthenosphere The grain-size field may focus melt toward the ridge axis.

Predict drug permeability to blood–brain-barrier from clinical phenotypes: drug side effects and drug indications

PubMed Central

Gao, Zhen; Chen, Yang; Cai, Xiaoshu; Xu, Rong

2017-01-01

Abstract Motivation: Blood–Brain-Barrier (BBB) is a rigorous permeability barrier for maintaining homeostasis of Central Nervous System (CNS). Determination of compound’s permeability to BBB is prerequisite in CNS drug discovery. Existing computational methods usually predict drug BBB permeability from chemical structure and they generally apply to small compounds passing BBB through passive diffusion. As abundant information on drug side effects and indications has been recorded over time through extensive clinical usage, we aim to explore BBB permeability prediction from a new angle and introduce a novel approach to predict BBB permeability from drug clinical phenotypes (drug side effects and drug indications). This method can apply to both small compounds and macro-molecules penetrating BBB through various mechanisms besides passive diffusion. Results: We composed a training dataset of 213 drugs with known brain and blood steady-state concentrations ratio and extracted their side effects and indications as features. Next, we trained SVM models with polynomial kernel and obtained accuracy of 76.0%, AUC 0.739, and F1 score (macro weighted) 0.760 with Monte Carlo cross validation. The independent test accuracy was 68.3%, AUC 0.692, F1 score 0.676. When both chemical features and clinical phenotypes were available, combining the two types of features achieved significantly better performance than chemical feature based approach (accuracy 85.5% versus 72.9%, AUC 0.854 versus 0.733, F1 score 0.854 versus 0.725; P < e−90). We also conducted de novo prediction and identified 110 drugs in SIDER database having the potential to penetrate BBB, which could serve as start point for CNS drug repositioning research. Availability and Implementation: https://github.com/bioinformatics-gao/CASE-BBB-prediction-Data Contact: rxx@case.edu Supplementary information: Supplementary data are available at Bioinformatics online. PMID:27993785

Effects of fracture surface roughness and shear displacement on geometrical and hydraulic properties of three-dimensional crossed rock fracture models

NASA Astrophysics Data System (ADS)

Huang, Na; Liu, Richeng; Jiang, Yujing; Li, Bo; Yu, Liyuan

2018-03-01

While shear-flow behavior through fractured media has been so far studied at single fracture scale, a numerical analysis of the shear effect on the hydraulic response of 3D crossed fracture model is presented. The analysis was based on a series of crossed fracture models, in which the effects of fracture surface roughness and shear displacement were considered. The rough fracture surfaces were generated using the modified successive random additions (SRA) algorithm. The shear displacement was applied on one fracture, and at the same time another fracture shifted along with the upper and lower surfaces of the sheared fracture. The simulation results reveal the development and variation of preferential flow paths through the model during the shear, accompanied by the change of the flow rate ratios between two flow planes at the outlet boundary. The average contact area accounts for approximately 5-27% of the fracture planes during shear, but the actual calculated flow area is about 38-55% of the fracture planes, which is much smaller than the noncontact area. The equivalent permeability will either increase or decrease as shear displacement increases from 0 to 4 mm, depending on the aperture distribution of intersection part between two fractures. When the shear displacement continuously increases by up to 20 mm, the equivalent permeability increases sharply first, and then keeps increasing with a lower gradient. The equivalent permeability of rough fractured model is about 26-80% of that calculated from the parallel plate model, and the equivalent permeability in the direction perpendicular to shear direction is approximately 1.31-3.67 times larger than that in the direction parallel to shear direction. These results can provide a fundamental understanding of fluid flow through crossed fracture model under shear.

Impact of Chemical Structure on Conjunctival Drug Permeability: Adopting Porcine Conjunctiva and Cassette Dosing for Construction of In Silico Model.

PubMed

Ramsay, Eva; Ruponen, Marika; Picardat, Théo; Tengvall, Unni; Tuomainen, Marjo; Auriola, Seppo; Toropainen, Elisa; Urtti, Arto; Del Amo, Eva M

2017-09-01

Conjunctiva occupies most of the ocular surface area, and conjunctival permeability affects ocular and systemic drug absorption of topical ocular medications. Therefore, the aim of this study was to obtain a computational in silico model for structure-based prediction of conjunctival drug permeability. This was done by employing cassette dosing and quantitative structure-property relationship (QSPR) approach. Permeability studies were performed ex vivo across fresh porcine conjunctiva and simultaneous dosing of a cassette mixture composed of 32 clinically relevant drug molecules with wide chemical space. The apparent permeability values were obtained using drug concentrations that were quantified with liquid chromatography tandem-mass spectrometry. The experimental data were utilized for building a QSPR model for conjunctival permeability predictions. The conjunctival permeability values presented a 17-fold range (0.63-10.74 × 10 -6 cm/s). The final QSPR had a Q 2 value of 0.62 and predicted the external test set with a mean fold error of 1.34. The polar surface area, hydrogen bond donor, and halogen ratio were the most relevant descriptors for defining conjunctival permeability. This work presents for the first time a predictive QSPR model of conjunctival drug permeability and a comprehensive description on conjunctival isolation from the porcine eye. The model can be used for developing new ocular drugs. Copyright © 2017 American Pharmacists Association®. Published by Elsevier Inc. All rights reserved.

Electric and Hydraulic Properties of Carbon Felt Immersed in Different Dielectric Liquids

PubMed Central

Kossenko, Alexey; Lugovskoy, Svetlana

2018-01-01

Electroconductive carbon felt (CF) material, having a permeable structure and significant electroconductive surface, is widely used for electrodes in numerous electrochemical applications such as redox flow batteries, fuel cells, electrochemical desalination apparatus, etc. The internal structure of CF is composed of different lengths of carbon filaments bonded together. This structure creates a large number of stochastically oriented and stochastically linked channels that have different lengths and cross sections. Therefore, the CF hydraulic permeability is similar to that of porous media and is determined by the internal empty volume and arrangement of carbon fibers. Its electroconductivity is ensured by the conductivity of the carbon filaments and by the electrical interconnections between fibers. Both of these properties (permeability and electrical conductivity) are extremely important for the efficient functioning of electrochemical devices. However, their influences counter each other during CF compressing. Increasing the stress on a felt element provides supplementary electrical contacts of carbon filaments, which lead to improved electrical conductivity. Thus, the active surface of the felt electrode is increased, which also boosts redox chemical reactions. On the other hand, compressed felt possesses reduced hydrodynamic permeability as a result of a diminished free volume of porous media and intrinsic channels. This causes increasing hydrodynamic expenditures of electrolyte pumping through electrodes and lessened cell (battery) efficiency. The designer of specific electrochemical systems has to take into account both of these properties when selecting the optimal construction for a cell. This article presents the results of measurements and novel approximating expressions of electrical and hydraulic characteristics of a CF during its compression. Since electrical conductivity plays a determining role in providing electrochemical reactions, it was measured in dry conditions and when the CF was immersed in several non-conductive liquids. The choice of such liquids prevented side effects of electrolyte ionic conductivity impact on electrical resistivity of the CF. This gave an opportunity to determine the influences of dielectric parameters of electrolytes to increase or decrease the density of interconnectivity of carbon fibers either between themselves or between them and electrodes. The experiments showed the influence of liquid permittivity on the conductivity of CF, probably by changing the density of fiber interconnections inside the felt. PMID:29690636

Electric and Hydraulic Properties of Carbon Felt Immersed in Different Dielectric Liquids.

PubMed

Kossenko, Alexey; Lugovskoy, Svetlana; Averbukh, Moshe

2018-04-23

Electroconductive carbon felt (CF) material, having a permeable structure and significant electroconductive surface, is widely used for electrodes in numerous electrochemical applications such as redox flow batteries, fuel cells, electrochemical desalination apparatus, etc. The internal structure of CF is composed of different lengths of carbon filaments bonded together. This structure creates a large number of stochastically oriented and stochastically linked channels that have different lengths and cross sections. Therefore, the CF hydraulic permeability is similar to that of porous media and is determined by the internal empty volume and arrangement of carbon fibers. Its electroconductivity is ensured by the conductivity of the carbon filaments and by the electrical interconnections between fibers. Both of these properties (permeability and electrical conductivity) are extremely important for the efficient functioning of electrochemical devices. However, their influences counter each other during CF compressing. Increasing the stress on a felt element provides supplementary electrical contacts of carbon filaments, which lead to improved electrical conductivity. Thus, the active surface of the felt electrode is increased, which also boosts redox chemical reactions. On the other hand, compressed felt possesses reduced hydrodynamic permeability as a result of a diminished free volume of porous media and intrinsic channels. This causes increasing hydrodynamic expenditures of electrolyte pumping through electrodes and lessened cell (battery) efficiency. The designer of specific electrochemical systems has to take into account both of these properties when selecting the optimal construction for a cell. This article presents the results of measurements and novel approximating expressions of electrical and hydraulic characteristics of a CF during its compression. Since electrical conductivity plays a determining role in providing electrochemical reactions, it was measured in dry conditions and when the CF was immersed in several non-conductive liquids. The choice of such liquids prevented side effects of electrolyte ionic conductivity impact on electrical resistivity of the CF. This gave an opportunity to determine the influences of dielectric parameters of electrolytes to increase or decrease the density of interconnectivity of carbon fibers either between themselves or between them and electrodes. The experiments showed the influence of liquid permittivity on the conductivity of CF, probably by changing the density of fiber interconnections inside the felt.

Structural and geochemical characteristics of faulted sediments and inferences on the role of water in deformatiion, Rio Grande Rift, New Mexico

USGS Publications Warehouse

Caine, Jonathan S.; Minor, S.A.

2009-01-01

The San Ysidro fault is a spectacularly exposed normal fault located in the northwestern Albuquerque Basin of the Rio Grande Rift. This intrabasin fault is representative of many faults that formed in poorly lithified sediments throughout the rift. The fault is exposed over nearly 10 km and accommodates nearly 700 m of dip slip in subhorizontal, siliciclastic sediments. The extent of the exposure facilitates study of along-strike variations in deformation mechanisms, archi tecture, geochemistry, and permeability. The fault is composed of structural and hydrogeologic components that include a clay-rich fault core, a calcite-cemented mixed zone, and a poorly developed damage zone primarily consisting of deformation bands. Structural textures suggest that initial deformation in the fault occurred at low temperature and pressure, was within the paleosaturated zone of the evolving Rio Grande Rift, and was dominated by particulate flow. Little geochemical change is apparent across the fault zone other than due to secondary processes. The lack of fault-related geochemical change is interpreted to reflect the fundamental nature of water-saturated, particulate fl ow. Early mechanical entrainment of low-permeability clays into the fault core likely caused damming of groundwater flow on the up-gradient, footwall side of the fault. This may have caused a pressure gradient and flow of calcite-saturated waters in higher-permeability, fault-entrained siliciclastic sediments, ultimately promoting their cementation by sparry calcite. Once developed, the cemented and clay-rich fault has likely been, and continues to be, a partial barrier to cross-fault groundwater flow, as suggested by petrophysical measurements. Aeromagnetic data indicate that there may be many more unmapped faults with similar lengths to the San Ysidro fault buried within Rio Grande basins. If these buried faults formed by the same processes that formed the San Ysidro fault and have persistent low-permeability cores and cemented mixed zones, they could compartmentalize the basin-fill aquifers more than is currently realized, particularly if pumping stresses continue to increase in response to population growth. ?? 2009 Geological Society of America.

Geologic framework of the Edwards Aquifer and upper confining unit, and hydrogeologic characteristics of the Edwards Aquifer, south-central Uvalde County, Texas

USGS Publications Warehouse

Clark, Allan K.; Small, Ted A.

1997-01-01

The stratigraphic units of the Edwards aquifer in south-central Uvalde County generally are porous and permeable. The stratigraphic units that compose the Edwards aquifer in south-central Uvalde County are the Devils River Formation in the Devils River trend; and the West Nueces, McKnight, and Salmon Peak Formations in the Maverick Basin. The Balcones fault zone is the principal structural feature in Uvalde County; however, the displacement along the fault zone is less in Uvalde County than in adjacent Medina and Bexar Counties to the east. The Uvalde Salient is a structural high in south-central Uvalde County, and consists of several closely connected crustal uplifts that bring Edwards aquifer strata to the surface generally forming prominent hills. The crustal uplifts forming this structural high are the remnants of intrusive and extrusive magnatic activity. Six primary faults—Cooks, Black Mountain, Blue Mountain, Uvalde, Agape, and Connor—cross the length of the study area from the southwest to the northeast juxtaposing the Lower Cretaceous Salmon Peak Formation at the surface in the northwestern part of the study area against Upper Cretaceous formations in the central part of the study area. In the study area, the porosity of the rocks in the Edwards aquifer is related to depositional or diagenetic elements along specific stratigraphic horizons (fabric selective) and to dissolution and structural elements that can occur in any lithostratigraphic horizon (not fabric selective). Permeability depends on the physical properties of the rock such as size, shape, distribution of pores, and fissuring and dissolution. The middle 185 feet of the lower part of the Devils River Formation, the upper part of the Devils River Formation, and the upper unit of the Salmon Peak Formation probably are the most porous and permeable stratigraphic zones of the Edwards aquifer in south-central Uvalde County.

Effects of rock mineralogy and pore structure on stress-dependent permeability of shale samples

PubMed Central

Al Ismail, Maytham I.; Zoback, Mark D.

2016-01-01

We conducted pulse-decay permeability experiments on Utica and Permian shale samples to investigate the effect of rock mineralogy and pore structure on the transport mechanisms using a non-adsorbing gas (argon). The mineralogy of the shale samples varied from clay rich to calcite rich (i.e. clay poor). Our permeability measurements and scanning electron microscopy images revealed that the permeability of the shale samples whose pores resided in the kerogen positively correlated with organic content. Our results showed that the absolute value of permeability was not affected by the mineral composition of the shale samples. Additionally, our results indicated that clay content played a significant role in the stress-dependent permeability. For clay-rich samples, we observed higher pore throat compressibility, which led to higher permeability reduction at increasing effective stress than with calcite-rich samples. Our findings highlight the importance of considering permeability to be stress dependent to achieve more accurate reservoir simulations especially for clay-rich shale reservoirs. This article is part of the themed issue ‘Energy and the subsurface’. PMID:27597792

Hydraulic head applications of flow logs in the study of heterogeneous aquifers

USGS Publications Warehouse

Paillet, Frederick L.

2001-01-01

Permeability profiles derived from high-resolution flow logs in heterogeneous aquifers provide a limited sample of the most permeable beds or fractures determining the hydraulic properties of those aquifers. This paper demonstrates that flow logs can also be used to infer the large-scale properties of aquifers surrounding boreholes. The analysis is based on the interpretation of the hydraulic head values estimated from the flow log analysis. Pairs of quasi-steady flow profiles obtained under ambient conditions and while either pumping or injecting are used to estimate the hydraulic head in each water-producing zone. Although the analysis yields localized estimates of transmissivity for a few water-producing zones, the hydraulic head estimates apply to the farfield aquifers to which these zones are connected. The hydraulic head data are combined with information from other sources to identify the large-scale structure of heterogeneous aquifers. More complicated cross-borehole flow experiments are used to characterize the pattern of connection between large-scale aquifer units inferred from the hydraulic head estimates. The interpretation of hydraulic heads in situ under steady and transient conditions is illustrated by several case studies, including an example with heterogeneous permeable beds in an unconsolidated aquifer, and four examples with heterogeneous distributions of bedding planes and/or fractures in bedrock aquifers.

Characterization of preferential flow paths between boreholes in fractured rock using a nanoscale zero-valent iron tracer test

NASA Astrophysics Data System (ADS)

Chuang, Po-Yu; Chia, Yeeping; Liou, Ya-Hsuan; Teng, Mao-Hua; Liu, Ching-Yi; Lee, Tsai-Ping

2016-11-01

Recent advances in borehole geophysical techniques have improved characterization of cross-hole fracture flow. The direct detection of preferential flow paths in fractured rock, however, remains to be resolved. In this study, a novel approach using nanoscale zero-valent iron (nZVI or `nano-iron') as a tracer was developed for detecting fracture flow paths directly. Generally, only a few rock fractures are permeable while most are much less permeable. A heat-pulse flowmeter can be used to detect changes in flow velocity for delineating permeable fracture zones in the borehole and providing the design basis for the tracer test. When nano-iron particles are released in an injection well, they can migrate through the connecting permeable fracture and be attracted to a magnet array when arriving in an observation well. Such an attraction of incoming iron nanoparticles by the magnet can provide quantitative information for locating the position of the tracer inlet. A series of field experiments were conducted in two wells in fractured rock at a hydrogeological research station in Taiwan, to test the cross-hole migration of the nano-iron tracer through permeable connected fractures. The fluid conductivity recorded in the observation well confirmed the arrival of the injected nano-iron slurry. All of the iron nanoparticles attracted to the magnet array in the observation well were found at the depth of a permeable fracture zone delineated by the flowmeter. This study has demonstrated that integrating the nano-iron tracer test with flowmeter measurement has the potential to characterize preferential flow paths in fractured rock.

Properties and Antioxidant Capacity of Anchovy (Engraulis encrasicholus) By-Product Protein Films Containing Thyme Essential Oil.

PubMed

Tural, Serpil; Turhan, Sadettin

2017-03-01

In this study, some properties and antioxidant capacity of anchovy ( Engraulis encrasicholus ) by-product protein films with added 0.5, 1.0 and 1.5% of thyme essential oil were investigated. The films with thyme essential oil had higher elongation at break, water vapour permeability and oxygen permeability, lower solubility and tensile strength than control film (p<0.05). The incorporation of thyme essential oil affected transparency values of the films, but only the addition of 1.5% of thyme essential oil significantly reduced the transparency (p<0.05). In the film matrix, molecular organisation and intermolecular interaction were changed by thyme essential oil addition. The films with thyme essential oil had a heterogeneous surface and a relatively smooth cross-section structure. Slightly higher phase transition and lower glass transition temperatures were observed in films with thyme essential oil. The antioxidant capacity of the films was improved by incorporating thyme essential oil depending on its volume fraction.

Properties and Antioxidant Capacity of Anchovy (Engraulis encrasicholus) By-Product Protein Films Containing Thyme Essential Oil

PubMed Central

Tural, Serpil

2017-01-01

Summary In this study, some properties and antioxidant capacity of anchovy (Engraulis encrasicholus) by-product protein films with added 0.5, 1.0 and 1.5% of thyme essential oil were investigated. The films with thyme essential oil had higher elongation at break, water vapour permeability and oxygen permeability, lower solubility and tensile strength than control film (p<0.05). The incorporation of thyme essential oil affected transparency values of the films, but only the addition of 1.5% of thyme essential oil significantly reduced the transparency (p<0.05). In the film matrix, molecular organisation and intermolecular interaction were changed by thyme essential oil addition. The films with thyme essential oil had a heterogeneous surface and a relatively smooth cross-section structure. Slightly higher phase transition and lower glass transition temperatures were observed in films with thyme essential oil. The antioxidant capacity of the films was improved by incorporating thyme essential oil depending on its volume fraction. PMID:28559736

Vascular Endothelial Growth Factor-A165b Restores Normal Glomerular Water Permeability in a Diphtheria-Toxin Mouse Model of Glomerular Injury.

PubMed

Stevens, Megan; Neal, Christopher R; Salmon, Andrew H J; Bates, David O; Harper, Steven J; Oltean, Sebastian

2018-01-01

Genetic cell ablation using the human diphtheria toxin receptor (hDTR) is a new strategy used for analysing cellular function. Diphtheria toxin (DT) is a cytotoxic protein that leaves mouse cells relatively unaffected, but upon binding to hDTR it ultimately leads to cell death. We used a podocyte-specific hDTR expressing (Pod-DTR) mouse to assess the anti-permeability and cyto-protective effects of the splice isoform vascular endothelial growth factor (VEGF-A165b). The Pod-DTR mouse was crossed with a mouse that over-expressed VEGF-A165b specifically in the podocytes (Neph-VEGF-A165b). Wild type (WT), Pod-DTR, Neph-VEGF-A165b and Pod-DTR X Neph-VEGF-A165b mice were treated with several doses of DT (1, 5, 100, and 1,000 ng/g bodyweight). Urine was collected and the glomerular water permeability (LpA/Vi) was measured ex vivo after 14 days. Structural analysis and podocyte marker expression were also assessed. Pod-DTR mice developed an increased glomerular LpA/Vi 14 days after administration of DT (all doses), which was prevented when the mice over-expressed VEGF-A165b. No major structural abnormalities, podocyte ablation or albuminuria was observed in Pod-DTR mice, indicating this to be a mild model of podocyte disease. However, a change in expression and localisation of nephrin within the podocytes was observed, indicating disruption of the slit diaphragm in the Pod-DTR mice. This was prevented in the Pod-DTR X Neph-VEGF-A165b mice. Although only a mild model of podocyte injury, over-expression of the anti-permeability VEGF-A165b isoform in the podocytes of Pod-DTR mice had a protective effect. Therefore, this study further highlights the therapeutic potential of VEGF-A165b in glomerular disease. © 2018 The Author(s) Published by S. Karger AG, Basel.

Numerical analysis of the impact of permeability on trailing-edge noise

NASA Astrophysics Data System (ADS)

Koh, Seong Ryong; Meinke, Matthias; Schröder, Wolfgang

2018-05-01

The impact of porous surfaces on the near-wall turbulent structures and the generated trailing-edge noise is analyzed for several trailing-edge shapes of finite thickness using a high resolution large-eddy simulation (LES)/computational aeroacoustics (CAA) method. The porous surface of the trailing edge is defined by the porosity and the viscous permeability determined by the solution of a turbulent flat plate boundary layer at a Reynolds number 1280 based on the displacement thickness in the inflow cross section. The volume-averaged approach for the homogeneous porous medium shows that the porous impedance scales linearly with the porosity and exponentially with the mean structure size of a porous medium. The drag induced by the porous surface changes the friction velocity and the permeability Reynolds number ReK which determines the porous impedance Rs scaled by ReK-2/3. The trailing-edge noise is analyzed for three solid and three porous trailing edges. The effect of a finite span is investigated by the spanwise correlation model based on the measured coherence distribution. The acoustic prediction shows a good agreement with measurements of the broadband spectrum and the strong tone generated by a finite trailing-edge thickness. The pressure gradient inside the porous media is redistributed by the Darcy drag defined by the viscous permeability and the porosity. The mean pressure increases in the upstream direction inside the porous medium such that the flow acceleration involved in the acoustic generation is reduced inside the porous medium. The noise reduction by a porous medium reaches 11 dB for the trailing-edge shape which possesses a sharp corner for the solid surface. The porous surface applied to a semi-circular trailing edge achieves a 4 dB noise reduction. The directivity pattern for individual components of the acoustic spectrum shows that the massive noise reduction is determined at the tone. Enhanced wave diffraction by the thick flat plate changes the directivity pattern in the high frequency range.

Chronic uremia induces permeability changes, increased nitric oxide synthase expression, and structural modifications in the peritoneum.

PubMed

Combet, S; Ferrier, M L; Van Landschoot, M; Stoenoiu, M; Moulin, P; Miyata, T; Lameire, N; Devuyst, O

2001-10-01

Advanced glycation end products (AGE), growth factors, and nitric oxide contribute to alterations of the peritoneum during peritoneal dialysis (PD). These mediators are also involved in chronic uremia, a condition associated with increased permeability of serosal membranes. It is unknown whether chronic uremia per se modifies the peritoneum before PD initiation. A rat model of subtotal nephrectomy was used to measure peritoneal permeability after 3, 6, and 9 wk, in parallel with peritoneal nitric oxide synthase (NOS) isoform expression and activity and structural changes. Uremic rats were characterized by a higher peritoneal permeability for small solutes and an increased NOS activity due to the up-regulation of endothelial and neuronal NOS. The permeability changes and increased NOS activities correlated with the degree of renal failure. Focal areas of vascular proliferation and fibrosis were detected in uremic rats, in relation with a transient up-regulation of vascular endothelial growth factor and basic fibroblast growth factor, as well as vascular deposits of the AGE carboxymethyllysine and pentosidine. Correction of anemia with erythropoietin did not prevent the permeability or structural changes in uremic rats. Thus, in this rat model, uremia induces permeability and structural changes in the peritoneum, in parallel with AGE deposits and up-regulation of specific NOS isoforms and growth factors. These data suggest an independent contribution of uremia in the peritoneal changes during PD and offer a paradigm to better understand the modifications of serosal membranes in uremia.

a Fractal Permeability Model Coupling Boundary-Layer Effect for Tight Oil Reservoirs

NASA Astrophysics Data System (ADS)

Wang, Fuyong; Liu, Zhichao; Jiao, Liang; Wang, Congle; Guo, Hu

A fractal permeability model coupling non-flowing boundary-layer effect for tight oil reservoirs was proposed. Firstly, pore structures of tight formations were characterized with fractal theory. Then, with the empirical equation of boundary-layer thickness, Hagen-Poiseuille equation and fractal theory, a fractal torturous capillary tube model coupled with boundary-layer effect was developed, and verified with experimental data. Finally, the parameters influencing effective liquid permeability were quantitatively investigated. The research results show that effective liquid permeability of tight formations is not only decided by pore structures, but also affected by boundary-layer distributions, and effective liquid permeability is the function of fluid type, fluid viscosity, pressure gradient, fractal dimension, tortuosity fractal dimension, minimum pore radius and maximum pore radius. For the tight formations dominated with nanoscale pores, boundary-layer effect can significantly reduce effective liquid permeability, especially under low pressure gradient.

Supercritical CO2 Migration under Cross-Bedded Structures: Outcrop Analog from the Jurassic Navajo Sandstone

NASA Astrophysics Data System (ADS)

Lee, S.; Allen, J.; Han, W.; Lu, C.; McPherson, B. J.

2011-12-01

Jurassic aeolian sandstones (e.g. Navajo and White Rim Sandstones) on the Colorado Plateau of Utah have been considered potential sinks for geologic CO2 sequestration due to their regional lateral continuity, thickness, high porosity and permeability, presence of seal strata and proximity to large point sources of anthropogenic CO2. However, aeolian deposits usually exhibit inherent internal complexities induced by migrating bedforms of different sizes and their resulting bounding surfaces. Therefore, CO2 plume migration in such complex media should be well defined and successively linked in models for better characterization of the plume behavior. Based on an outcrop analog of the upper Navajo Sandstone in the western flank of the San Rafael Swell, Utah, we identified five different bedform types with dune and interdune facies to represent the spatial continuity of lithofacies units. Using generated 3D geometrical facies patterns of cross-bedded structures in the Navajo Sandstone, we performed numerical simulations to understand the detailed behavior of CO2 plume migration under the different cross-bedded bedforms. Our numerical simulation results indicate that cross-bedded structures (bedform types) play an important role on governing the rate and directionality of CO2 migration, resulting in changes of imbibition processes of CO2. CO2 migration tends to follow wind ripple laminations and reactivation surfaces updip. Our results suggest that geologically-based upscaling of CO2 migration is crucial in cross-bedded formations as part of reservoir or basin scale models. Furthermore, comparative modeling studies between 3D models and 2D cross-sections extracted from 3D models showed the significant three-dimensional interplay in a cross-bedded structure and the need to correctly capture the geologic heterogeneity to predict realistic CO2 plume behavior. Our outcrop analog approach presented in this study also demonstrates an alternative method for assessing geologic CO2 storage in deep formations when scarce data is available.

Effects of eddy current and dispersion of magnetic anisotropy on the high-frequency permeability of Fe-based nanocomposites

NASA Astrophysics Data System (ADS)

Han, M.; Rozanov, K. N.; Zezyulina, P. A.; Wu, Yan-Hui

2015-06-01

Fe-Cu-Nb-Si-B microflakes have been prepared by ball milling. The structural, magnetostatic and microwave permeability of the flakes and flake-filled composites have been studied. Two ferromagnetic phases, nanograins and amorphous matrix, are found in the flakes. The Mössbauer study shows that the nanograins are α-Fe3(Si) with D03 superlattice structure. High resolution transmission electron microscopy shows that the nanograins are well dispersed in the matrix. The microwave permeability of composites containing the flakes has been measured. The comparison of the intrinsic permeability of the flakes obtained from the permeability measurements and from the anisotropy field distribution reveals a disagreement in the magnetic loss peak location. It is concluded that the low-frequency loss in the composites is not due to the effect of eddy currents. The low-frequency loss may be attributed to other sources, such as domain wall motion or peculiarities of the magnetic structure of the flakes in the composite.

Sialic acids regulate microvessel permeability, revealed by novel in vivo studies of endothelial glycocalyx structure and function

PubMed Central

Betteridge, Kai B.; Arkill, Kenton P.; Neal, Christopher R.; Harper, Steven J.; Foster, Rebecca R.; Satchell, Simon C.; Bates, David O.

2017-01-01

Key points We have developed novel techniques for paired, direct, real‐time in vivo quantification of endothelial glycocalyx structure and associated microvessel permeability.Commonly used imaging and analysis techniques yield measurements of endothelial glycocalyx depth that vary by over an order of magnitude within the same vessel.The anatomical distance between maximal glycocalyx label and maximal endothelial cell plasma membrane label provides the most sensitive and reliable measure of endothelial glycocalyx depth.Sialic acid residues of the endothelial glycocalyx regulate glycocalyx structure and microvessel permeability to both water and albumin. Abstract The endothelial glycocalyx forms a continuous coat over the luminal surface of all vessels, and regulates multiple vascular functions. The contribution of individual components of the endothelial glycocalyx to one critical vascular function, microvascular permeability, remains unclear. We developed novel, real‐time, paired methodologies to study the contribution of sialic acids within the endothelial glycocalyx to the structural and functional permeability properties of the same microvessel in vivo. Single perfused rat mesenteric microvessels were perfused with fluorescent endothelial cell membrane and glycocalyx labels, and imaged with confocal microscopy. A broad range of glycocalyx depth measurements (0.17–3.02 μm) were obtained with different labels, imaging techniques and analysis methods. The distance between peak cell membrane and peak glycocalyx label provided the most reliable measure of endothelial glycocalyx anatomy, correlating with paired, numerically smaller values of endothelial glycocalyx depth (0.078 ± 0.016 μm) from electron micrographs of the same portion of the same vessel. Disruption of sialic acid residues within the endothelial glycocalyx using neuraminidase perfusion decreased endothelial glycocalyx depth and increased apparent solute permeability to albumin in the same vessels in a time‐dependent manner, with changes in all three true vessel wall permeability coefficients (hydraulic conductivity, reflection coefficient and diffusive solute permeability). These novel technologies expand the range of techniques that permit direct studies of the structure of the endothelial glycocalyx and dependent microvascular functions in vivo, and demonstrate that sialic acid residues within the endothelial glycocalyx are critical regulators of microvascular permeability to both water and albumin. PMID:28524373

Study on Surface Permeability of Concrete under Immersion

PubMed Central

Liu, Jun; Xing, Feng; Dong, Biqin; Ma, Hongyan; Pan, Dong

2014-01-01

In this paper, concrete specimens are immersed in ultrapure water, to study the evolutions of surface permeability, pore structure and paste microstructure following the prolonging of immersion period. According to the results, after 30-day immersion, the surface permeability of concrete becomes higher as compared with the value before immersion. However, further immersion makes the surface permeability decrease, so that the value measured after 150-day immersion is only half that measured after 30-day immersion. The early increase in surface permeability should be mainly attributed to the leaching of calcium hydroxide, while the later decrease to the refinement of pore structure due to hydration. The two effects work simultaneously and compete throughout the immersion period. The proposed mechanisms get support from microscopic measurements and observations. PMID:28788490

A Fractal Permeability Model for Shale Oil Reservoir

NASA Astrophysics Data System (ADS)

Zhang, Tao; Dong, Mingzhe; Li, Yajun

2018-01-01

In this work, a fractal analytical model is proposed to predict the permeability of shale reservoir. The proposed model explicitly relates the permeability to the micro-structural parameters (tortuosity, pore area fractal dimensions, porosity and slip velocity coefficient) of shale.

Cracks in the Palisade Cuticle of Soybean Seed Coats Correlate with their Permeability to Water

PubMed Central

MA, FENGSHAN; CHOLEWA, EWA; MOHAMED, TASNEEM; PETERSON, CAROL A.; GIJZEN, MARK

2004-01-01

• Background and Aims Soybean (Glycine max) is among the many legumes that are well known for ‘hardseededness’. This feature can be beneficial for long-term seed survival, but is undesirable for the food processing industry. There is substantial disagreement concerning the mechanisms and related structures that control the permeability properties of soybean seed coats. In this work, the structural component that controls water entry into the seed is identified. • Methods Six soybean cultivars were tested for their seed coat permeabilities to water. To identify the structural feature(s) that may contribute to the determination of these permeabilities, fluorescent tracer dyes, and light and electron microscopic techniques were used. • Key Results The cultivar ‘Tachanagaha’ has the most permeable seed coat, ‘OX 951’ the least permeable seed coat, and the permeabilities of the rest (‘Harovinton’, ‘Williams’, ‘Clark L 67-3469’, and ‘Harosoy 63’) are intermediate. All seeds have surface deposits, depressions, a light line, and a cuticle about 0·2 µm thick overlaying the palisade layer. In permeable cultivars the cuticle tends to break, whereas in impermeable seeds of ‘OX 951’ it remains intact. In the case of permeable seed coats, the majority of the cracks are from 1 to 5 µm wide and from 20 to 200 µm long, and occur more frequently on the dorsal side than in other regions of the seed coat, a position that correlates with the site of initial water uptake. • Conclusions The cuticle of the palisade layer is the key factor that determines the permeability property of a soybean seed coat. The cuticle of a permeable seed coat is mechanically weak and develops small cracks through which water can pass. The cuticle of an impermeable seed coat is mechanically strong and does not crack under normal circumstances. PMID:15217785

Dynamic permeability in fault damage zones induced by repeated coseismic fracturing events

NASA Astrophysics Data System (ADS)

Aben, F. M.; Doan, M. L.; Mitchell, T. M.

2017-12-01

Off-fault fracture damage in upper crustal fault zones change the fault zone properties and affect various co- and interseismic processes. One of these properties is the permeability of the fault damage zone rocks, which is generally higher than the surrounding host rock. This allows large-scale fluid flow through the fault zone that affects fault healing and promotes mineral transformation processes. Moreover, it might play an important role in thermal fluid pressurization during an earthquake rupture. The damage zone permeability is dynamic due to coseismic damaging. It is crucial for earthquake mechanics and for longer-term processes to understand how the dynamic permeability structure of a fault looks like and how it evolves with repeated earthquakes. To better detail coseismically induced permeability, we have performed uniaxial split Hopkinson pressure bar experiments on quartz-monzonite rock samples. Two sample sets were created and analyzed: single-loaded samples subjected to varying loading intensities - with damage varying from apparently intact to pulverized - and samples loaded at a constant intensity but with a varying number of repeated loadings. The first set resembles a dynamic permeability structure created by a single large earthquake. The second set resembles a permeability structure created by several earthquakes. After, the permeability and acoustic velocities were measured as a function of confining pressure. The permeability in both datasets shows a large and non-linear increase over several orders of magnitude (from 10-20 up to 10-14 m2) with an increasing amount of fracture damage. This, combined with microstructural analyses of the varying degrees of damage, suggests a percolation threshold. The percolation threshold does not coincide with the pulverization threshold. With increasing confining pressure, the permeability might drop up to two orders of magnitude, which supports the possibility of large coseismic fluid pulses over relatively large distances along a fault. Also, a relatively small threshold could potentially increase permeability in a large volume of rock, given that previous earthquakes already damaged these rocks.

Predicting permeability of regular tissue engineering scaffolds: scaling analysis of pore architecture, scaffold length, and fluid flow rate effects.

PubMed

Rahbari, A; Montazerian, H; Davoodi, E; Homayoonfar, S

2017-02-01

The main aim of this research is to numerically obtain the permeability coefficient in the cylindrical scaffolds. For this purpose, a mathematical analysis was performed to derive an equation for desired porosity in terms of morphological parameters. Then, the considered cylindrical geometries were modeled and the permeability coefficient was calculated according to the velocity and pressure drop values based on the Darcy's law. In order to validate the accuracy of the present numerical solution, the obtained permeability coefficient was compared with the published experimental data. It was observed that this model can predict permeability with the utmost accuracy. Then, the effect of geometrical parameters including porosity, scaffold pore structure, unit cell size, and length of the scaffolds as well as entrance mass flow rate on the permeability of porous structures was studied. Furthermore, a parametric study with scaling laws analysis of sample length and mass flow rate effects on the permeability showed good fit to the obtained data. It can be concluded that the sensitivity of permeability is more noticeable at higher porosities. The present approach can be used to characterize and optimize the scaffold microstructure due to the necessity of cell growth and transferring considerations.

Evaluation of permeable fractures in rock aquifers

NASA Astrophysics Data System (ADS)

Bok Lee, Hang

2015-04-01

In this study, the practical usefulness and fundamental applicability of a self-potential (SP) method for identifying the permeable fractures were evaluated by a comparison of SP methods with other geophysical logging methods and hydraulic tests. At a 10 m-shallow borehole in the study site, the candidates of permeable fractures crossing the borehole were first determined by conventional geophysical methods such as an acoustic borehole televiwer, temperature, electrical conductivity and gamma-gamma loggings, which was compared to the analysis by the SP method. Constant pressure injection and recovery tests were conducted for verification of the hydraulic properties of the fractures identified by various logging methods. The acoustic borehole televiwer and gamma-gamma loggings detected the open space or weathering zone within the borehole, but they cannot prove the possibility of a groundwater flow through the detected fractures. The temperature and electrical conductivity loggings had limitations to detect the fractured zones where groundwater in the borehole flows out to the surrounding rock aquifers. Comparison of results from different methods showed that there is a best correlation between the distribution of hydraulic conductivity and the variation of the SP signals, and the SP logging can estimate accurately the hydraulic activity as well as the location of permeable fractures. Based on the results, the SP method is recommended for determining the hydraulically-active fractures rather than other conventional geophysical loggings. This self-potential method can be effectively applied in the initial stage of a site investigation which selects the optimal location and evaluates the hydrogeological property of fractures in target sites for the underground structure including the geothermal reservoir and radioactive waste disposal.

The dynamics of coherent flow structures within a submerged permeable bed

NASA Astrophysics Data System (ADS)

Blois, G.; Best, J.; Sambrook Smith, G.; Hardy, R. J.; Lead, J.

2009-12-01

The existence of complex 3D coherent vortical structures in turbulent boundary layers has been widely reported from experimental observations (Adrian et al., 2007, Christensen and Adrian, 2001) and investigations of natural open channel flows (e.g. Kostaschuk and Church, 1993; Best, 2005). The interaction between these flow structures and the solid boundary that is responsible for their generation is also receiving increasing attention due to the central role played by turbulence in governing erosion-deposition processes. Yet, for the majority of studies, the bed roughness has been represented using rough impermeable surfaces. While not inherently acknowledged, most research in this area is thus only strictly applicable to those natural river beds composed either of bedrock or clay, or that have armoured, impermeable, surfaces. Recently, many researchers have noted the need to account for the role of bed permeability in order to accurately reproduce the true nature of flow over permeable gravel-bed rivers. For these cases, the near-bed flow is inherently and mutually linked to the interstitial-flow occurring in the porous solid matrix. This interaction is established through turbulence mechanisms occurring across the interface that may be important for influencing the incipient motion of cohesionless sediment. However, the nature of this turbulence and the formation of coherent structures within such permeable beds remain substantially unresolved due to the technical challenges of collecting direct data in this region. In this paper, we detail the existence and dynamic nature of coherent vortical structures within the individual pore spaces of a permeable bed submerged by a free stream flow. Laboratory experiments are reported in which a permeable flume bed was constructed using spheres packed in an offset cubic arrangement. We applied a high resolution E-PIV (Endoscopic Particle Image Velocimetry) approach in order to fully resolve the instantaneous structure of flow within the permeable bed, which allowed visualisation of coherent vortices in the pore space, and investigation of their formative mechanisms and spatio-temporal evolution. The spatial scale of these structures is found to be of the order of the pore space, with jet flows occurring between interconnected pores and interacting with the spherical particles constituting the solid matrix. Such jets are hypothesized to be triggered by the interstitial pressure gradients between interconnected pores, which in turn are linked to large-scale coherent flow structures in the free-flow that advect and propagate through the permeable bed. As the jet flow interacts with the matrix around the pore space, coherent flow structures are generated with both clockwise and anticlockwise rotation. The nature of these subsurface turbulent flow patterns will be presented, which allows new insight into flows within permeable beds and the hydrodynamic processes triggering the motion of sediment.

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 monitoring, in-situ hydraulic test, and core measurement using drill holes to better understand fault zone hydraulic properties.

EMERGING TECHNOLOGY BULLETIN: A CROSS-FLOW PERVAPORATION SYSTEM FOR REMOVAL OF VOCS FROM CONTAMINATED WASTEWATER

EPA Science Inventory

Pervaporation is a process for removing volatile organic compounds (VOC) from contaminated water. The performance of the cross-flow pervaporation system increases with temperature, with an equipment limitation of 35 degrees Celsius. Permeable membranes that preferentially adsor...

Method for directional hydraulic fracturing

DOEpatents

Swanson, David E.; Daly, Daniel W.

1994-01-01

A method for directional hydraulic fracturing using borehole seals to confine pressurized fluid in planar permeable regions, comprising: placing a sealant in the hole of a structure selected from geologic or cemented formations to fill the space between a permeable planar component and the geologic or cemented formation in the vicinity of the permeable planar component; making a hydraulic connection between the permeable planar component and a pump; permitting the sealant to cure and thereby provide both mechanical and hydraulic confinement to the permeable planar component; and pumping a fluid from the pump into the permeable planar component to internally pressurize the permeable planar component to initiate a fracture in the formation, the fracture being disposed in the same orientation as the permeable planar component.

Microscale diffusion measurements and simulation of a scaffold with a permeable strut.

PubMed

Lee, Seung Youl; Lee, Byung Ryong; Lee, Jongwan; Kim, Seongjun; Kim, Jung Kyung; Jeong, Young Hun; Jin, Songwan

2013-10-10

Electrospun nanofibrous structures provide good performance to scaffolds in tissue engineering. We measured the local diffusion coefficients of 3-kDa FITC-dextran in line patterns of electrospun nanofibrous structures fabricated by the direct-write electrospinning (DWES) technique using the fluorescence recovery after photobleaching (FRAP) method. No significant differences were detected between DWES line patterns fabricated with polymer supplied at flow rates of 0.1 and 0.5 mL/h. The oxygen diffusion coefficients of samples were estimated to be ~92%-94% of the oxygen diffusion coefficient in water based on the measured diffusion coefficient of 3-kDa FITC-dextran. We also simulated cell growth and distribution within spatially patterned scaffolds with struts consisting of either oxygen-permeable or non-permeable material. The permeable strut scaffolds exhibited enhanced cell growth. Saturated depths at which cells could grow to confluence were 15% deeper for the permeable strut scaffolds than for the non-permeable strut scaffold.

Crosslinked Polybenzimidazole Membrane For Gas Separation

DOEpatents

Jorgensen, Betty S.; Young, Jennifer S.; Espinoza, Brent F.

2005-09-20

A cross-linked, supported polybenzimidazole membrane for gas separation is prepared by layering a solution of polybenzimidazole (PBI) and a,a'dibromo-p-xylene onto a porous support and evaporating solvent. A supported membrane of cross-linked poly-2,2'-(m-phenylene)-5,5'-bibenzimidazole unexpectedly exhibits an enhanced gas permeability compared to the non-cross linked analog at temperatures over 265° C.

Development of an ion-pair to improve the colon permeability of a low permeability drug: Atenolol.

PubMed

Lozoya-Agullo, Isabel; González-Álvarez, Isabel; González-Álvarez, Marta; Merino-Sanjuán, Matilde; Bermejo, Marival

2016-10-10

To ensure the optimal performance of oral controlled release formulations, drug colon permeability is one of the critical parameters. Consequently developing this kind of formulations for low permeability molecules requires strategies to increase their ability to cross the colonic membrane. The objective of this work is to show if an ion-pair formation can improve the colon permeability of atenolol as a low permeability drug model. Two counter ions have been tested: brilliant blue and bromophenol blue. The Distribution coefficients at pH7.00 (DpH7) of atenolol, atenolol + brilliant blue and atenolol + bromophenol blue were experimentally determined in n-octanol. Moreover, the colonic permeability was determined in rat colon using in situ closed loop perfusion method based in Doluisio's Technique. To check the potential effects of the counter ions on the membrane integrity, a histological assessment of colonic tissue was done. The results of the partitioning studies were inconclusive about ion-pair formation; nevertheless colon permeability was significantly increased by both counter ions (from 0.232±0.021cm/s to 0.508±0.038cm/s in the presence of brilliant blue and to 0.405±0.044cm/s in the presence of bromophenol blue). Neither damage on the membrane was observed on the histological studies, nor any change on paracellular permeability suggesting that the permeability enhancement could be attributed to the ion-pair formation. Copyright © 2016 Elsevier B.V. All rights reserved.

Coating gigaporous polystyrene microspheres with cross-linked poly(vinyl alcohol) hydrogel as a rapid protein chromatography matrix.

PubMed

Qu, Jian-Bo; Huan, Guan-Sheng; Chen, Yan-Li; Zhou, Wei-Qing; Liu, Jian-Guo; Huang, Fang

2014-08-13

Gigaporous polystyrene (PS) microspheres were hydrophilized by in situ polymerization to give a stable cross-linked poly(vinyl alcohol) (PVA) hydrogel coating, which can shield proteins from the hydrophobic PS surface underneath. The amination of microspheres (PS-NH2) was first carried out through acetylization, oximation and reduction, and then 4,4'-azobis (4-cyanovaleric acid) (ACV), a polymerization initiator, was covalently immobilized on PS-NH2 through amide bond formation, and the cross-linked poly(vinyl acetate) (PVAc) was prepared by radical polymerization at the surfaces of ACV-immobilized PS microspheres (PS-ACV). Finally, the cross-linked PVA hydrogel coated gigaporous PS microspheres (PS-PVA) was easily achieved through alcoholysis of PVAc. Results suggested that the PS microspheres were effectively coated with cross-linked PVA hydrogel, where the gigaporrous structure remained under optimal conditions. After hydrophilic modification (PS-PVA), the protein-resistant ability of microspheres was greatly improved. The hydroxyl-rich PS-PVA surface can be easily derivatized by classical chemical methods. Performance advantages of the PS-PVA column in flow experiment include good permeability, low backpressure, and mechanical stability. These results indicated that PS-PVA should be promising in rapid protein chromatography.

Characterization of tumor microvascular structure and permeability: comparison between magnetic resonance imaging and intravital confocal imaging

NASA Astrophysics Data System (ADS)

Reitan, Nina Kristine; Thuen, Marte; Goa, Pa˚L. Erik; de Lange Davies, Catharina

2010-05-01

Solid tumors are characterized by abnormal blood vessel organization, structure, and function. These abnormalities give rise to enhanced vascular permeability and may predict therapeutic responses. The permeability and architecture of the microvasculature in human osteosarcoma tumors growing in dorsal window chambers in athymic mice were measured by confocal laser scanning microscopy (CLSM) and dynamic contrast enhanced magnetic resonance imaging (DCE-MRI). Dextran (40 kDa) and Gadomer were used as molecular tracers for CLSM and DCE-MRI, respectively. A significant correlation was found between permeability indicators. The extravasation rate Ki as measured by CLSM correlated positively with DCE-MRI parameters, such as the volume transfer constant Ktrans and the initial slope of the contrast agent concentration-time curve. This demonstrates that these two techniques give complementary information. Extravasation was further related to microvascular structure and was found to correlate with the fractal dimension and vascular density. The structural parameter values that were obtained from CLSM images were higher for abnormal tumor vasculature than for normal vessels.

Biofilm Effect on Flow Structure over a Permeable Bed

NASA Astrophysics Data System (ADS)

Kazemifar, F.; Blois, G.; Aybar, M.; Perez-Calleja, P.; Nerenberg, R.; Sinha, S.; Hardy, R. J.; Best, J.; Sambrook Smith, G.; Christensen, K. T.

2017-12-01

Biofilms constitute an important form of bacterial life in aquatic environments and are present at the fluid-solid interfaces in natural and industrial settings, such as water distribution systems and riverbeds among others. The permeable, heterogeneous, and deformable structure of biofilms can influence mass and momentum transport between the subsurface and freestream. However, this interaction is not fully understood, in part due to technical obstacles impeding quantitative experimental investigations. In this work, the effect of biofilm on flow structure over a permeable bed is studied. Experiments are conducted in a closed water channel equipped with an idealized two-dimensional permeable bed. Prior to conducting flow experiments, the models are placed within an independent recirculating reactor for biofilm growth. Once a targeted biofilm growth stage is achieved, the models are transferred to the water channel and subjected to transitional and turbulent flows. Long-distance microscopic particle image velocimetry measurements are performed to quantify the effect of biofilm on the turbulence structure of the free flow as well as the freestream-subsurface flow interaction.

Ionic liquid compatibility in polyethylene oxide/siloxane ion gel membranes

DOE PAGES

Kusuma, Victor A.; Macala, Megan K.; Liu, Jian; ...

2018-10-02

Ion gel films were prepared by incorporating eight commercially available ionic liquids in two different cross-linked polymer matrices to evaluate their phase miscibility, gas permeability and ionic conductivity for potential applications as gas separation membranes and solid electrolyte materials. The ionic liquids cations were 1-ethyl-3-methylimidazolium, 1-ethyl-3-methylpyridinium, 1-butyl-1-methylpyrrolidinium, tributylmethylphosphonium, and butyltrimethylammonium with a common anion (bis(trifluoromethylsulfonyl)imide). In addition, ionic liquids with 1-ethyl-3-methylimidazolium cation with acetate, dicyanamide and tetrafluoroborate counterions were evaluated. The two polymers were cross-linked poly(ethylene oxide) and cross-linked poly(ethylene oxide)/siloxane copolymer. Differential scanning calorimetry, X-ray diffractometry and visual observations were performed to evaluate the ion gels’ miscibility, thermal stabilitymore » and homogeneity. Ionic liquids with the least basic anion (bis(trifluoromethylsulfonyl)imide) and aromatic cations containing acidic proton (e.g. imidazolium and pyridinium) gave the most stable and miscible ion gels. Phase stability was shown to be a function of both ionic liquid content and temperature, with phase separation observed at elevated temperatures. In conclusion, gas permeability testing with carbon dioxide and nitrogen and ionic conductivity measurements confirmed that these ionic liquids increased the gas permeability and ionic conductivity of the polymers.« less

Ionic liquid compatibility in polyethylene oxide/siloxane ion gel membranes

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

Kusuma, Victor A.; Macala, Megan K.; Liu, Jian

Ion gel films were prepared by incorporating eight commercially available ionic liquids in two different cross-linked polymer matrices to evaluate their phase miscibility, gas permeability and ionic conductivity for potential applications as gas separation membranes and solid electrolyte materials. The ionic liquids cations were 1-ethyl-3-methylimidazolium, 1-ethyl-3-methylpyridinium, 1-butyl-1-methylpyrrolidinium, tributylmethylphosphonium, and butyltrimethylammonium with a common anion (bis(trifluoromethylsulfonyl)imide). In addition, ionic liquids with 1-ethyl-3-methylimidazolium cation with acetate, dicyanamide and tetrafluoroborate counterions were evaluated. The two polymers were cross-linked poly(ethylene oxide) and cross-linked poly(ethylene oxide)/siloxane copolymer. Differential scanning calorimetry, X-ray diffractometry and visual observations were performed to evaluate the ion gels’ miscibility, thermal stabilitymore » and homogeneity. Ionic liquids with the least basic anion (bis(trifluoromethylsulfonyl)imide) and aromatic cations containing acidic proton (e.g. imidazolium and pyridinium) gave the most stable and miscible ion gels. Phase stability was shown to be a function of both ionic liquid content and temperature, with phase separation observed at elevated temperatures. In conclusion, gas permeability testing with carbon dioxide and nitrogen and ionic conductivity measurements confirmed that these ionic liquids increased the gas permeability and ionic conductivity of the polymers.« less

Large-scale model of flow in heterogeneous and hierarchical porous media

NASA Astrophysics Data System (ADS)

Chabanon, Morgan; Valdés-Parada, Francisco J.; Ochoa-Tapia, J. Alberto; Goyeau, Benoît

2017-11-01

Heterogeneous porous structures are very often encountered in natural environments, bioremediation processes among many others. Reliable models for momentum transport are crucial whenever mass transport or convective heat occurs in these systems. In this work, we derive a large-scale average model for incompressible single-phase flow in heterogeneous and hierarchical soil porous media composed of two distinct porous regions embedding a solid impermeable structure. The model, based on the local mechanical equilibrium assumption between the porous regions, results in a unique momentum transport equation where the global effective permeability naturally depends on the permeabilities at the intermediate mesoscopic scales and therefore includes the complex hierarchical structure of the soil. The associated closure problem is numerically solved for various configurations and properties of the heterogeneous medium. The results clearly show that the effective permeability increases with the volume fraction of the most permeable porous region. It is also shown that the effective permeability is sensitive to the dimensionality spatial arrangement of the porous regions and in particular depends on the contact between the impermeable solid and the two porous regions.

Oligomeric structure and functional characterization of Caenorhabditis elegans Innexin-6 gap junction protein.

PubMed

Oshima, Atsunori; Matsuzawa, Tomohiro; Nishikawa, Kouki; Fujiyoshi, Yoshinori

2013-04-12

Innexin is the molecular component of invertebrate gap junctions. Here we successfully expressed and purified Caenorhabditis elegans innexin-6 (INX-6) gap junction channels and characterized the molecular dimensions and channel permeability using electron microscopy (EM) and microinjection of fluorescent dye tracers, respectively. Negative staining and thin-section EM of isolated INX-6 gap junction membranes revealed a loosely packed hexagonal lattice and a greater cross-sectional width than that of connexin26 and connexin43 (Cx43)-GFP. In gel filtration analysis, the elution profile of purified INX-6 channels in dodecyl maltoside solution exhibited a peak at ∼400 kDa that was shifted to ∼800 kDa in octyl glucose neopentyl glycol. We also obtained the class averages of purified INX-6 channels from these peak fractions by single particle analysis. The class average from the ∼800-kDa fraction showed features of the junction form with a longitudinal height of 220 Å, a channel diameter of 110 Å in the absence of detergent micelles, and an extracellular gap space of 60 Å, whereas the class averages from the ∼400-kDa fraction showed diameters of up to 140 Å in the presence of detergent micelles. These findings indicate that the purified INX-6 channels are predominantly hemichannels in dodecyl maltoside and docked junction channels in octyl glucose neopentyl glycol. Dye transfer experiments revealed that the INX-6-GFP-His channels are permeable to 3- and 10-kDa tracers, whereas no significant amounts of these tracers passed through the Cx43-GFP channels. Based on these findings, INX-6 channels have a larger overall structure and greater permeability than connexin channels.

Oligomeric Structure and Functional Characterization of Caenorhabditis elegans Innexin-6 Gap Junction Protein*

PubMed Central

Oshima, Atsunori; Matsuzawa, Tomohiro; Nishikawa, Kouki; Fujiyoshi, Yoshinori

2013-01-01

Innexin is the molecular component of invertebrate gap junctions. Here we successfully expressed and purified Caenorhabditis elegans innexin-6 (INX-6) gap junction channels and characterized the molecular dimensions and channel permeability using electron microscopy (EM) and microinjection of fluorescent dye tracers, respectively. Negative staining and thin-section EM of isolated INX-6 gap junction membranes revealed a loosely packed hexagonal lattice and a greater cross-sectional width than that of connexin26 and connexin43 (Cx43)-GFP. In gel filtration analysis, the elution profile of purified INX-6 channels in dodecyl maltoside solution exhibited a peak at ∼400 kDa that was shifted to ∼800 kDa in octyl glucose neopentyl glycol. We also obtained the class averages of purified INX-6 channels from these peak fractions by single particle analysis. The class average from the ∼800-kDa fraction showed features of the junction form with a longitudinal height of 220 Å, a channel diameter of 110 Å in the absence of detergent micelles, and an extracellular gap space of 60 Å, whereas the class averages from the ∼400-kDa fraction showed diameters of up to 140 Å in the presence of detergent micelles. These findings indicate that the purified INX-6 channels are predominantly hemichannels in dodecyl maltoside and docked junction channels in octyl glucose neopentyl glycol. Dye transfer experiments revealed that the INX-6-GFP-His channels are permeable to 3- and 10-kDa tracers, whereas no significant amounts of these tracers passed through the Cx43-GFP channels. Based on these findings, INX-6 channels have a larger overall structure and greater permeability than connexin channels. PMID:23460640

Hot and Steamy Fractures in the Philippines: The Geological Characterization and Permeability Evaluation of Fractures in the Southern Negros Geothermal Field, Philippines

NASA Astrophysics Data System (ADS)

Pastoriza, L. R.; Holdsworth, R.; McCaffrey, K. J. W.; Dempsey, E. D.; Walker, R. J.; Gluyas, J.; Reyes, J. K.

2016-12-01

Fluid flow pathway characterization is critical to geothermal exploration and exploitation. It requires a good understanding of the structural evolution, fault distribution and fluid flow properties. A dominantly fieldwork-based approach has been used to evaluate the potential fracture permeability characteristics of a typical high-temperature geothermal reservoir in the Southern Negros Geothermal Field, Philippines. This is a liquid-dominated geothermal resource hosted in the andesitic to dacitic Quaternary Cuernos de Negros Volcano in Negros Island. Fieldwork reveals two main fracture groups based on fault rock characteristics, alteration type, relative age of deformation, and associated thermal manifestation, with the younger fractures mainly related to the development of the modern geothermal system. Palaeostress analyses of cross-cutting fault and fracture arrays reveal a progressive counterclockwise rotation of stress axes from the (?)Pliocene up to the present-day, which is consistent with the regional tectonic models. A combined slip and dilation tendency analysis of the mapped faults indicates that NW-SE structures should be particularly promising drilling targets. Frequency versus length and aperture plots of fractures across six to eight orders of magnitude show power-law relationships with a change in scaling exponent in the region of 100 to 500m length-scales. Finally, evaluation of the topology of the fracture branches shows the dominance of Y-nodes that are mostly doubly connected suggesting good connectivity and permeability within the fracture networks. The results obtained in this study illustrate the value of methods that can be globally applied during exploration to better characterize fracture systems in geothermal reservoirs using multiscale datasets.

Hot and steamy fractures in the Philippines: the characterisation and permeability evaluation of fractures of the Southern Negros Geothermal Field, Negros Oriental, Philippines

NASA Astrophysics Data System (ADS)

Pastoriza, Loraine; Holdsworth, Robert; McCaffrey, Kenneth; Dempsey, Eddie; Walker, Richard; Gluyas, Jon; Reyes, Jonathan

2017-04-01

Fluid flow pathway characterisation is critical to geothermal exploration and exploitation. It requires a good understanding of the structural evolution, fault distribution and fluid flow properties. A dominantly fieldwork-based approach has been used to evaluate the potential fracture permeability characteristics of a typical high-temperature geothermal reservoir in the Southern Negros Geothermal Field, Philippines. This is a liquid-dominated geothermal resource hosted in the andesitic to dacitic Quaternary Cuernos de Negros Volcano in Negros Island. Fieldwork reveals two main fracture groups based on fault rock characteristics, alteration type, relative age of deformation, and associated thermal manifestation, with the younger fractures mainly related to the development of the modern geothermal system. Palaeostress analyses of cross-cutting fault and fracture arrays reveal a progressive counterclockwise rotation of stress axes from the (?)Pliocene up to the present-day, which is consistent with the regional tectonic models. A combined slip and dilation tendency analysis of the mapped faults indicates that NW-SE structures should be particularly promising drilling targets. Frequency versus length and aperture plots of fractures across six to eight orders of magnitude show power-law relationships with a change in scaling exponent in the region of 100 to 500m length-scales. Finally, evaluation of the topology of the fracture branches shows the dominance of Y-nodes that are mostly doubly connected suggesting good connectivity and permeability within the fracture networks. The results obtained in this study illustrate the value of methods that can be globally applied during exploration to better characterize fracture systems in geothermal reservoirs using multiscale datasets.

From mitochondrial large amplitude swelling to the permeability transition - a short historic overview.

PubMed

Wojtczak, Lech; Więckowski, Mariusz R

An outline of studies on the mitochondrial large conductance permeability pore is presented starting from the early observations in the 1950s on the large amplitude mitochondrial swelling, through the concept of the permeability transition and various theories on the structure of the related permeability transition pore, up to its present identification as a part of mitochondrial (F 1 F O ) ATPase/ATP synthase.

Investigation of negative permeability metamaterials for wireless power transfer

NASA Astrophysics Data System (ADS)

Xin, Wenhui; Mi, Chunting Chris; He, Fei; Jiang, Meng; Hua, Dengxin

2017-11-01

In order to enhance the transmission efficiency of wireless power transfer (WPT), a negative permeability metamaterials (NPM) with a structure of honeycomb composed by units of hexagon-shaped spirals copper is proposed in this paper. The unit parameters of the NPM are optimized, to make sure the negative permeability at the special frequency. The S-parameters of the designed NPM are measured by a network analyzer and the permeability is extracted, it shows the honeycomb NPM has a negative permeability at 6.43 MHz. A two-coil WPT is setup and the transmission efficiency of WPT embedded with NPM at the different position and with different structure are investigated. The measured results show that the 2-slab honeycomb NPM have a good perform compared with the 1-slab NPM, and the efficiency can be increased up to 51%. The results show that honeycomb NPM embedded in the WPT help to improve the transmission efficiency remarkable.

Experiment to verify the permeability of Hele-Shaw cells

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

Hartline, B.K.; Lister, C.R.B.

1978-04-01

A fluid layer sandwiched between 2 flat plates (Hele-Shaw cell) has been assumed to model a saturated porous medium with permeability, D2/12, dependent only on the gap width, D. For situations where the properties of the porous matrix are important, such as thermal convection, the total cross section (Y) of the sandwich should enter into the computation of permeability. To decide which of these approaches is valid, the onset of convection was observed in a Hele-Shaw cell with constant gap width but spatially varying wall thickness. Convection begins in the thin-walled section at a lower temperature difference than it doesmore » where the walls are thick. Data confirm that D3/12Y is the permeability of Hele-Shaw cells used to model thermal convection in porous layers.« less

Optimizing solubility and permeability of a biopharmaceutics classification system (BCS) class 4 antibiotic drug using lipophilic fragments disturbing the crystal lattice.

PubMed

Tehler, Ulrika; Fagerberg, Jonas H; Svensson, Richard; Larhed, Mats; Artursson, Per; Bergström, Christel A S

2013-03-28

Esterification was used to simultaneously increase solubility and permeability of ciprofloxacin, a biopharmaceutics classification system (BCS) class 4 drug (low solubility/low permeability) with solid-state limited solubility. Molecular flexibility was increased to disturb the crystal lattice, lower the melting point, and thereby improve the solubility, whereas lipophilicity was increased to enhance the intestinal permeability. These structural changes resulted in BCS class 1 analogues (high solubility/high permeability) emphasizing that simple medicinal chemistry may improve both these properties.

Structural basis for the inhibition of voltage-dependent K+ channel by gating modifier toxin

PubMed Central

Ozawa, Shin-ichiro; Kimura, Tomomi; Nozaki, Tomohiro; Harada, Hitomi; Shimada, Ichio; Osawa, Masanori

2015-01-01

Voltage-dependent K+ (Kv) channels play crucial roles in nerve and muscle action potentials. Voltage-sensing domains (VSDs) of Kv channels sense changes in the transmembrane potential, regulating the K+-permeability across the membrane. Gating modifier toxins, which have been used for the functional analyses of Kv channels, inhibit Kv channels by binding to VSD. However, the structural basis for the inhibition remains elusive. Here, fluorescence and NMR analyses of the interaction between VSD derived from KvAP channel and its gating modifier toxin, VSTx1, indicate that VSTx1 recognizes VSD under depolarized condition. We identified the VSD-binding residues of VSTx1 and their proximal residues of VSD by the cross-saturation (CS) and amino acid selective CS experiments, which enabled to build a docking model of the complex. These results provide structural basis for the specific binding and inhibition of Kv channels by gating modifier toxins. PMID:26382304

Resin Film Infusion (RFI) Process Modeling for Large Transport Aircraft Wing Structures

NASA Technical Reports Server (NTRS)

Knott, Tamara W.; Loos, Alfred C.

2000-01-01

Resin film infusion (RFI) is a cost-effective method for fabricating stiffened aircraft wing structures. The RFI process lends itself to the use of near net shape textile preforms manufactured through a variety of automated textile processes such as knitting and braiding. Often, these advanced fiber architecture preforms have through-the-thickness stitching for improved damage tolerance and delamination resistance. The challenge presently facing RFI is to refine the process to ensure complete infiltration and cure of a geometrically complex shape preform with the high fiber volume fraction needed for structural applications. An accurate measurement of preform permeability is critical for successful modeling of the RFI resin infiltration process. Small changes in the permeability can result in very different infiltration behavior and times. Therefore, it is important to accurately measure the permeabilities of the textile preforms used in the RFI process. The objective of this investigation was to develop test methods that can be used to measure the compaction behavior and permeabilities of high fiber volume fraction, advanced fiber architecture textile preforms. These preforms are often highly compacted due to through-the-thickness stitching used to improve damage tolerance. Test fixtures were designed and fabricated and used to measure both transverse and in-plane permeabilities. The fixtures were used to measure the permeabilities of multiaxial warp knit and triaxial braided preforms at fiber volume fractions from 55% to 65%. In addition, the effects of stitching characteristics, thickness, and batch variability on permeability and compaction behavior were investigated.

Sulfolane-Cross-Polybenzimidazole Membrane For Gas Separation

DOEpatents

Young, Jennifer S.; Long, Gregory S.; Espinoza, Brent F.

2006-02-14

A cross-linked, supported polybenzimidazole membrane for gas separation is prepared by reacting polybenzimidazole (PBI) with the sulfone-containing crosslinking agent 3,4-dichloro-tetrahydro-thiophene-1,1-dioxide. The cross-linked reaction product exhibits enhanced gas permeability to hydrogen, carbon dioxide, nitrogen, and methane as compared to the unmodified analog, without significant loss of selectivity, at temperatures from about 20 degrees Celsius to about 400 degrees Celsius.

Automated Coastal Engineering System: Technical Reference

DTIC Science & Technology

1992-09-01

of Contents ACES Technical Reference Wave Transmission Through Permeable Structures ..................................... 5-4 Littoral Processes...A-2 Table A-4: Grain-Size Scales ( Soil Classification) ..................................... A-3 Table A-5: Major Tidal Constituents... Permeable Structures Lonphore Sediment Tranaport Littoral Numerical Si~ulation of Time-Dependent Beach and Dune Erosion Processes Calculation of Composite

Method for the preparation of high surface area high permeability carbons

DOEpatents

Lagasse, Robert R.; Schroeder, John L.

1999-05-11

A method for preparing carbon materials having high surface area and high macropore volume to provide high permeability. These carbon materials are prepared by dissolving a carbonizable polymer precursor, in a solvent. The solution is cooled to form a gel. The solvent is extracted from the gel by employing a non-solvent for the polymer. The non-solvent is removed by critical point drying in CO.sub.2 at an elevated pressure and temperature or evaporation in a vacuum oven. The dried product is heated in an inert atmosphere in a first heating step to a first temperature and maintained there for a time sufficient to substantially cross-link the polymer material. The cross-linked polymer material is then carbonized in an inert atmosphere.

Internal architecture, permeability structure, and hydrologic significance of contrasting fault-zone types

NASA Astrophysics Data System (ADS)

Rawling, Geoffrey C.; Goodwin, Laurel B.; Wilson, John L.

2001-01-01

The Sand Hill fault is a steeply dipping, large-displacement normal fault that cuts poorly lithified Tertiary sediments of the Albuquerque basin, New Mexico, United States. The fault zone does not contain macroscopic fractures; the basic structural element is the deformation band. The fault core is composed of foliated clay flanked by structurally and lithologically heterogeneous mixed zones, in turn flanked by damage zones. Structures present within these fault-zone architectural elements are different from those in brittle faults formed in lithified sedimentary and crystalline rocks that do contain fractures. These differences are reflected in the permeability structure of the Sand Hill fault. Equivalent permeability calculations indicate that large-displacement faults in poorly lithified sediments have little potential to act as vertical-flow conduits and have a much greater effect on horizontal flow than faults with fractures.

Microfluidic passive permeability assay using nanoliter droplet interface lipid bilayers.

PubMed

Nisisako, Takasi; Portonovo, Shiva A; Schmidt, Jacob J

2013-11-21

Membrane permeability assays play an important role in assessing drug transport activities across biological membranes. However, in conventional parallel artificial membrane permeability assays (PAMPA), the membrane model used is dissimilar to biological membranes physically and chemically. Here, we describe a microfluidic passive permeability assay using droplet interface bilayers (DIBs). In a microfluidic network, nanoliter-sized donor and acceptor aqueous droplets are alternately formed in cross-flowing oil containing phospholipids. Subsequently, selective removal of oil through hydrophobic pseudo-porous sidewalls induces the contact of the lipid monolayers, creating arrayed planar DIBs between the donor and acceptor droplets. Permeation of fluorescein from the donor to the acceptor droplets was fluorometrically measured. From the measured data and a simple diffusion model we calculated the effective permeabilities of 5.1 × 10(-6) cm s(-1), 60.0 × 10(-6) cm s(-1), and 87.6 × 10(-6) cm s(-1) with donor droplets at pH values of 7.5, 6.4 and 5.4, respectively. The intrinsic permeabilities of specific monoanionic and neutral fluorescein species were obtained similarly. We also measured the permeation of caffeine in 10 min using UV microspectroscopy, obtaining a permeability of 20.8 × 10(-6) cm s(-1). With the small solution volumes, short measurement time, and ability to measure a wide range of compounds, this device has considerable potential as a platform for high-throughput drug permeability assays.

Stimuli-responsive cross-linked micelles for on-demand drug delivery against cancers

PubMed Central

Li, Yuanpei; Xiao, Kai; Zhu, Wei; Deng, Wenbin; Lam, Kit S.

2013-01-01

Stimuli-responsive cross-linked micelles (SCMs) represent an ideal nanocarrier system for drug delivery against cancers. SCMs exhibit superior structural stability compared to their non-crosslinked counterpart. Therefore, these nanocarriers are able to minimize the premature drug release during blood circulation. The introduction of environmentally sensitive crosslinkers or assembly units makes SCMs responsive to single or multiple stimuli present in tumor local microenvironment or exogenously applied stimuli. In these instances, the payload drug is released almost exclusively in cancerous tissue or cancer cells upon accumulation via enhanced permeability and retention effect or receptor mediated endocytosis. In this review, we highlight recent advances in the development of SCMs for cancer therapy. We also introduce the latest biophysical techniques, such as electron paramagnetic resonance (EPR) spectroscopy and fluorescence resonance energy transfer (FRET), for the characterization of the interactions between SCMs and blood proteins. PMID:24060922

Dynamic Fluid in a Porous Transducer-Based Angular Accelerometer

PubMed Central

Cheng, Siyuan; Fu, Mengyin; Wang, Meiling; Ming, Li; Fu, Huijin; Wang, Tonglei

2017-01-01

This paper presents a theoretical model of the dynamics of liquid flow in an angular accelerometer comprising a porous transducer in a circular tube of liquid. Wave speed and dynamic permeability of the transducer are considered to describe the relation between angular acceleration and the differential pressure on the transducer. The permeability and streaming potential coupling coefficient of the transducer are determined in the experiments, and special prototypes are utilized to validate the theoretical model in both the frequency and time domains. The model is applied to analyze the influence of structural parameters on the frequency response and the transient response of the fluidic system. It is shown that the radius of the circular tube and the wave speed affect the low frequency gain, as well as the bandwidth of the sensor. The hydrodynamic resistance of the transducer and the cross-section radius of the circular tube can be used to control the transient performance. The proposed model provides the basic techniques to achieve the optimization of the angular accelerometer together with the methodology to control the wave speed and the hydrodynamic resistance of the transducer. PMID:28230793

Simulating the heterogeneity in braided channel belt deposits: 2. Examples of results and comparison to natural deposits

NASA Astrophysics Data System (ADS)

Guin, Arijit; Ramanathan, Ramya; Ritzi, Robert W.; Dominic, David F.; Lunt, Ian A.; Scheibe, Timothy D.; Freedman, Vicky L.

2010-04-01

In part 1 of this paper (Ramanathan et al., 2010b) we presented a methodology and a code for modeling the hierarchical sedimentary architecture in braided channel belt deposits. Here in part 2, the code was used to create a digital model of this architecture and the corresponding spatial distribution of permeability. The simulated architecture was compared to the real stratal architecture observed in an abandoned channel belt. The comparisons included assessments of similarity which were both qualitative and quantitative. The qualitative comparisons show that the geometries of unit types within the synthetic deposits are generally consistent with field observations. The unit types in the synthetic deposits would generally be recognized as representing their counterparts in nature, including cross stratasets, lobate and scroll bar deposits, and channel fills. Furthermore, the synthetic deposits have a hierarchical spatial relationship among these units consistent with observations from field exposures and geophysical images. In quantitative comparisons the proportions and the length, width, and height of unit types at different scales, across all levels of the stratal hierarchy, compare well between the synthetic and the natural deposits. A number of important attributes of the synthetic channel belt deposits are shown to be influenced by more than one level within the hierarchy of stratal architecture. First, the high-permeability open-framework gravels connected across all levels and thus formed preferential flow pathways; open-framework gravels are known to form preferential flow pathways in natural channel belt deposits. The nature of a connected cluster changed across different levels of the stratal hierarchy, and as a result of the geologic structure, the connectivity occurs at proportions of open-framework gravels below the theoretical percolation threshold for random infinite media. Second, when the channel belt model was populated with permeability distributions by lowest-level unit type, the composite permeability semivariogram contained structures that were identifiable at more than one scale, and each of these structures could be directly linked to unit types of different scales existing at different levels within the hierarchy of strata. These collective results are encouraging with respect to our goal that this model be relevant for testing ideas in future research on flow and transport in aquifers and reservoirs with multiscale heterogeneity.

Bottom-up approach for microstructure optimization of sound absorbing materials.

PubMed

Perrot, Camille; Chevillotte, Fabien; Panneton, Raymond

2008-08-01

Results from a numerical study examining micro-/macrorelations linking local geometry parameters to sound absorption properties are presented. For a hexagonal structure of solid fibers, the porosity phi, the thermal characteristic length Lambda('), the static viscous permeability k(0), the tortuosity alpha(infinity), the viscous characteristic length Lambda, and the sound absorption coefficient are computed. Numerical solutions of the steady Stokes and electrical equations are employed to provide k(0), alpha(infinity), and Lambda. Hybrid estimates based on direct numerical evaluation of phi, Lambda('), k(0), alpha(infinity), Lambda, and the analytical model derived by Johnson, Allard, and Champoux are used to relate varying (i) throat size, (ii) pore size, and (iii) fibers' cross-section shapes to the sound absorption spectrum. The result of this paper tends to demonstrate the important effect of throat size in the sound absorption level, cell size in the sound absorption frequency selectivity, and fibers' cross-section shape in the porous material weight reduction. In a hexagonal porous structure with solid fibers, the sound absorption level will tend to be maximized with a 48+/-10 microm throat size corresponding to an intermediate resistivity, a 13+/-8 microm fiber radius associated with relatively small interfiber distances, and convex triangular cross-section shape fibers allowing weight reduction.

Unconventional Tight Reservoirs Characterization with Nuclear Magnetic Resonance

NASA Astrophysics Data System (ADS)

Santiago, C. J. S.; Solatpour, R.; Kantzas, A.

2017-12-01

The increase in tight reservoir exploitation projects causes producing many papers each year on new, modern, and modified methods and techniques on estimating characteristics of these reservoirs. The most ambiguous of all basic reservoir property estimations deals with permeability. One of the logging methods that is advertised to predict permeability but is always met by skepticism is Nuclear Magnetic Resonance (NMR). The ability of NMR to differentiate between bound and movable fluids and providing porosity increased the capability of NMR as a permeability prediction technique. This leads to a multitude of publications and the motivation of a review paper on this subject by Babadagli et al. (2002). The first part of this presentation is dedicated to an extensive review of the existing correlation models for NMR based estimates of tight reservoir permeability to update this topic. On the second part, the collected literature information is used to analyze new experimental data. The data are collected from tight reservoirs from Canada, the Middle East, and China. A case study is created to apply NMR measurement in the prediction of reservoir characterization parameters such as porosity, permeability, cut-offs, irreducible saturations etc. Moreover, permeability correlations are utilized to predict permeability. NMR experiments were conducted on water saturated cores. NMR T2 relaxation times were measured. NMR porosity, the geometric mean relaxation time (T2gm), Irreducible Bulk Volume (BVI), and Movable Bulk Volume (BVM) were calculated. The correlation coefficients were computed based on multiple regression analysis. Results are cross plots of NMR permeability versus the independently measured Klinkenberg corrected permeability. More complicated equations are discussed. Error analysis of models is presented and compared. This presentation is beneficial in understanding existing tight reservoir permeability models. The results can be used as a guide for choosing the best permeability estimation model for tight reservoirs data.

Evaluation of surface resistivity measurements as an alternative to the rapid chloride permeability test for quality assurance and acceptance : LTRC research project capsule 10-1C.

DOT National Transportation Integrated Search

2010-02-01

Many entities currently use permeability specifications in Portland cement : concrete (PCC) pavements and structures. For those states using : permeability specifications, two test methods are generally used and include : ASTM C 1202 (Standard Test M...

Porosity modification during and following deposition of deep-water sediments

NASA Astrophysics Data System (ADS)

Butler, R. W.; McCaffrey, W. D.; Haughton, P.; del Pino Sanchez, A.; Barker, S.; Hailwood, E.; Hakes, B.

2005-12-01

Deposition and early burial of sediments, especially sandy turbidites, are commonly accompanied by the reorganization of porosity structure through the localized expulsion of interstitial fluid. Fluid escape structures are preserved as thin sheets and pipes. Coeval sediment remobilization may be represented by shear structures, commonly taken to indicate down-slope creep and slumping. The history of shearing vs dewatering may be established from cross-cutting structures preserved in outcrop and/or core. Although these relationships are known for gravity-driven soft-sediment deformation on submarine slopes, they can also develop during deposition itself due to shear from the over-riding flow. Such deformation features, including pseudo s-c fabrics and distributed shear, together may previously have been misinterpreted as indicators of palaeoslope (slumps) or even of tectonic deformation. Progressive aggradation of sandy turbidites can show complex banded facies within which soft-sediment deformation is tiered. Syn-deposition micro-growth strata testify to ongoing seabed deformation occurring beneath active flows, while the bedforms themselves provide direct measurements of the magnitude of shear stresses imparted into the seabed and estimates of the shear strength of this substrate. Such banded facies may be interpreted in terms of cyclic partitioning of shear stress into the flow and the substrate. The modified porosity structures and related heterogeneities in permeability of such materials may persist during deeper burial, influencing the rheology of the sediment. These bed-scale processes are reflected in the quality and flow rates of hydrocarbon reservoirs. The reorganization of sand-body architecture through remobilization, by traction and/or down-slope failure, also has a strong impact on the permeability on the multi-bed scale (10s-100s m). Examples will be presented from hydrocarbon reservoirs in the subsurface and from outcrops of Tertiary turbidites in the Alpine-Apennine orogenic system.

Generation, Analysis and Characterization of Anisotropic Engineered Meta Materials

NASA Astrophysics Data System (ADS)

Trifale, Ninad T.

A methodology for a systematic generation of highly anisotropic micro-lattice structures was investigated. Multiple algorithms for generation and validation of engineered structures are developed and evaluated. Set of all possible permutations of structures for an 8-node cubic unit cell were considered and the degree of anisotropy of meta-properties in heat transport and mechanical elasticity were evaluated. Feasibility checks were performed to ensure that the generated unit cell network was repeatable and a continuous lattice structure. Four different strategies for generating permutations of the structures are discussed. Analytical models were developed to predict effective thermal, mechanical and permeability characteristics of these cellular structures.Experimentation and numerical modeling techniques were used to validate the models that are developed. A self-consistent mechanical elasticity model was developed which connects the meso-scale properties to stiffness of individual struts. A three dimensional thermal resistance network analogy was used to evaluate the effective thermal conductivity of the structures. The struts were modeled as a network of one dimensional thermal resistive elements and effective conductivity evaluated. Models were validated against numerical simulations and experimental measurements on 3D printed samples. Model was developed to predict effective permeability of these engineered structures based on Darcy's law. Drag coefficients were evaluated for individual connections in transverse and longitudinal directions and an interaction term was calibrated from the experimental data in literature in order to predict permeability. Generic optimization framework coupled to finite element solver is developed for analyzing any application involving use of porous structures. An objective functions were generated structure to address frequently observed trade-off between the stiffness, thermal conductivity, permeability and porosity. Three application were analyzed for potential use of engineered materials. Heat spreader application involving thermal and mechanical constraints, artificial bone grafts application involving mechanical and permeability constraints and structural materials applications involving mechanical, thermal and porosity constraints is analyzed. Recommendations for optimum topologies for specific operating conditions are provided.

Permeability measurement and control for epoxy composites

NASA Astrophysics Data System (ADS)

Chang, Tsun-Hsu; Tsai, Cheng-Hung; Wong, Wei-Syuan; Chen, Yen-Ren; Chao, Hsien-Wen

2017-08-01

The coupling of the electric and magnetic fields leads to a strong interplay in materials' permittivity and permeability. Here, we proposed a specially designed cavity, called the mu cavity. The mu cavity, consisting of a mushroom structure inside a cylindrical resonator, is exclusively sensitive to permeability, but not to permittivity. It decouples materials' electromagnetic properties and allows an accurate measurement of the permeability. With the help of an epsilon cavity, these two cavities jointly determine the complex permeability and permittivity of the materials at microwave frequencies. Homemade epoxy-based composite materials were prepared and tested. Measurement and manipulation of the permeability and permittivity of the epoxy composites will be shown. The results will be compared with the effective medium theories.

Biofilm effect on flow structure over a permeable bed

NASA Astrophysics Data System (ADS)

Kazemifar, Farzan; Blois, Gianluca; Aybar, Marcelo; Perez-Calleja, Patricia; Nerenberg, Robert; Sinha, Sumit; Hardy, Richard; Best, James; Sambrook Smith, Gregory; Christensen, Kenneth

2017-11-01

Biofilms constitute an important form of bacterial life in aquatic environments and are present at the fluid-solid interfaces in natural and industrial settings, such as water distribution systems and riverbeds among others. The permeable, heterogeneous, and deformable structure of biofilms can influence mass and momentum transport between the subsurface and freestream. However, this interaction is not fully understood, in part due to technical obstacles impeding quantitative experimental investigations. In this work, the effect of biofilm on flow structure over a permeable bed is studied. Experiments are conducted in a closed water channel equipped with an idealized two-dimensional permeable bed. Prior to conducting flow experiments, the models are placed within an independent recirculating reactor for biofilm growth. Once a targeted biofilm growth stage is achieved, the models are transferred to the water channel and subjected to transitional and turbulent flows. Long-distance microscopic particle image velocimetry measurements are performed to quantify the effect of biofilm on the turbulence structure of the free flow as well as the freestream-subsurface flow interaction. Funded by UK Natural Environment Research Council.

The permeability of the endplate channel to organic cations in frog muscle

PubMed Central

1980-01-01

The relative permeability of endplate channels to many organic cations was determined by reversal-potential criteria. Endplate currents induced by iontophoretic "puffs" of acetylcholine were studied by a Vaseline gap, voltage clamp method in cut muscle fibers. Reversal potential changes were measured as the NaCl of the bathing medium was replaced by salts of organic cations, and permeability ratios relative to Na+ ions were calculated from the Goldman-Hodgkin-Katz equation. 40 small monovalent organic cations had permeability ratios larger than 0.1. The most permeant including NH4+, hydroxylamine, hydrazine, methylamine, guanidine, and several relatives of guanidine had permeability ratios in the range 1.3--2.0. However, even cations such as imidazole, choline, tris(hydroxymethyl)aminomethane, triethylamine, and glycine methylester were appreciably permeant with permeability ratios of 0.13--0.95. Four compounds with two charged nitrogen groups were also permeant. Molecular models of the permeant ions suggest that the smallest cross-section of the open pore must be at least as large as a square, 6.5 A x 6.5 A. Specific chemical factors seem to be less important than access or friction in determining the ionic selectivity of the endplate channel. PMID:6247422

Possible Links between Intestinal Permeablity and Food Processing: A Potential Therapeutic Niche for Glutamine

PubMed Central

Rapin, Jean Robert; Wiernsperger, Nicolas

2010-01-01

Increased intestinal permeability is a likely cause of various pathologies, such as allergies and metabolic or even cardiovascular disturbances. Intestinal permeability is found in many severe clinical situations and in common disorders such as irritable bowel syndrome. In these conditions, substances that are normally unable to cross the epithelial barrier gain access to the systemic circulation. To illustrate the potential harmfulness of leaky gut, we present an argument based on examples linked to protein or lipid glycation induced by modern food processing. Increased intestinal permeability should be largely improved by dietary addition of compounds, such as glutamine or curcumin, which both have the mechanistic potential to inhibit the inflammation and oxidative stress linked to tight junction opening. This brief review aims to increase physician awareness of this common, albeit largely unrecognized, pathology, which may be easily prevented or improved by means of simple nutritional changes. PMID:20613941

Water permeability in hydrate-bearing sediments: A pore-scale study

NASA Astrophysics Data System (ADS)

Dai, Sheng; Seol, Yongkoo

2014-06-01

Permeability is a critical parameter governing methane flux and fluid flow in hydrate-bearing sediments; however, limited valid data are available due to experimental challenges. Here we investigate the relationship between apparent water permeability (k') and hydrate saturation (Sh), accounting for hydrate pore-scale growth habit and meso-scale heterogeneity. Results from capillary tube models rely on cross-sectional tube shapes and hydrate pore habits, thus are appropriate only for sediments with uniform hydrate distribution and known hydrate pore character. Given our pore network modeling results showing that accumulating hydrate in sediments decreases sediment porosity and increases hydraulic tortuosity, we propose a modified Kozeny-Carman model to characterize water permeability in hydrate-bearing sediments. This model agrees well with experimental results and can be easily implemented in reservoir simulators with no empirical variables other than Sh. Results are also relevant to flow through other natural sediments that undergo diagenesis, salt precipitation, or bio-clogging.

Greater scaffold permeability promotes growth of osteoblastic cells in a perfused bioreactor.

PubMed

Fan, Jie; Jia, Xiaoling; Huang, Yan; Fu, Bingmei M; Fan, Yubo

2015-12-01

Pore size and porosity have been widely acknowledged as important structural factors in tissue-engineered scaffolds. In fact, scaffolds with similar pore size and porosity can provide important and varied permeability due to different pore shape, interconnectivity and tortuosity. However, the effects of scaffold permeability on seeded cells remains largely unknown during tissue regeneration in vitro. In this study, we measured the Darcy permeability (K) of tri-calcium phosphate scaffolds by distributed them into three groups: Low, Medium and High. As a result, the effects of scaffold permeability on cell proliferation, cellular activity and growth in the inner pores were investigated in perfused and static cultures in vitro. Results demonstrated that higher permeable scaffolds exhibited superior performance during bone regeneration in vitro and the advantages of higher scaffold permeability were amplified in perfused culture. Based on these findings, scaffold permeability should be considered in future scaffold fabrications. Copyright © 2013 John Wiley & Sons, Ltd.

Along-axis hydrothermal flow at the axis of slow spreading Mid-Ocean Ridges: Insights from numerical models of the Lucky Strike vent field (MAR)

NASA Astrophysics Data System (ADS)

Fontaine, Fabrice J.; Cannat, Mathilde; Escartin, Javier; Crawford, Wayne C.

2014-07-01

processes and efficiency of hydrothermal heat extraction along the axis of mid-ocean ridges are controlled by lithospheric thermal and permeability structures. Hydrothermal circulation models based on the structure of fast and intermediate spreading ridges predict that hydrothermal cell organization and vent site distribution are primarily controlled by the thermodynamics of high-temperature mid-ocean ridge hydrothermal fluids. Using recent constraints on shallow structure at the slow spreading Lucky Strike segment along the Mid-Atlantic Ridge, we present a physical model of hydrothermal cooling that incorporates the specificities of a magma-rich slow spreading environment. Using three-dimensional numerical models, we show that, in contrast to the aforementioned models, the subsurface flow at Lucky Strike is primarily controlled by across-axis permeability variations. Models with across-axis permeability gradients produce along-axis oriented hydrothermal cells and an alternating pattern of heat extraction highs and lows that match the distribution of microseismic clusters recorded at the Lucky Strike axial volcano. The flow is also influenced by temperature gradients at the base of the permeable hydrothermal domain. Although our models are based on the structure and seismicity of the Lucky Strike segment, across-axis permeability gradients are also likely to occur at faster spreading ridges and these results may also have important implications for the cooling of young crust at fast and intermediate spreading centers.

Stereochemistry Balances Cell Permeability and Solubility in the Naturally Derived Phepropeptin Cyclic Peptides.

PubMed

Schwochert, Joshua; Lao, Yongtong; Pye, Cameron R; Naylor, Matthew R; Desai, Prashant V; Gonzalez Valcarcel, Isabel C; Barrett, Jaclyn A; Sawada, Geri; Blanco, Maria-Jesus; Lokey, R Scott

2016-08-11

Cyclic peptide (CP) natural products provide useful model systems for mapping "beyond-Rule-of-5" (bRo5) space. We identified the phepropeptins as natural product CPs with potential cell permeability. Synthesis of the phepropeptins and epimeric analogues revealed much more rapid cellular permeability for the natural stereochemical pattern. Despite being more cell permeable, the natural compounds exhibited similar aqueous solubility as the corresponding epimers, a phenomenon explained by solvent-dependent conformational flexibility among the natural compounds. When analyzing the polarity of the solution structures we found that neither the number of hydrogen bonds nor the total polar surface area accurately represents the solvation energies of the high and low dielectric conformations. This work adds to a growing number of natural CPs whose solvent-dependent conformational behavior allows for a balance between aqueous solubility and cell permeability, highlighting structural flexibility as an important consideration in the design of molecules in bRo5 chemical space.

Phenotypic heterogeneity in lung capillary and extra-alveolar endothelial cells. Increased extra-alveolar endothelial permeability is sufficient to decrease compliance.

PubMed

Lowe, Kevin; Alvarez, Diego; King, Judy; Stevens, Troy

2007-11-01

In acute respiratory distress syndrome, pulmonary vascular permeability increases, causing intravascular fluid and protein to move into the lung's interstitium. The classic model describing the formation of pulmonary edema suggests that fluid crossing the capillary endothelium is drawn by negative interstitial pressure into the potential space surrounding extra-alveolar vessels and, as interstitial pressure builds, is forced into the alveolar air space. However, the validity of this model is challenged by animal models of acute lung injury in which extra-alveolar vessels are more permeable than capillaries under a variety of conditions. In the current study, we sought to determine whether extravascular fluid accumulation can be produced because of increased permeability of either the capillary or extra-alveolar endothelium, and whether different pathophysiology results from such site-specific increases in permeability. We perfused isolated lungs with either the plant alkaloid thapsigargin, which increases extra-alveolar endothelial permeability, or with 4alpha-phorbol 12, 13-didecanoate, which increases capillary endothelial permeability. Both treatments produced equal increases in whole lung vascular permeability, but caused fluid accumulations in separate anatomical compartments. Light microscopy of isolated lungs showed that thapsigargin caused fluid cuffing of large vessels, while 4alpha-phorbol 12, 13-didecanoate caused alveolar flooding. Dynamic compliance was reduced in lungs with cuffing of large vessels, but not in lungs with alveolar flooding. Phenotypic differences between vascular segments resulted in site-specific increases in permeability, which have different pathophysiological outcomes. Our findings suggest that insults leading to acute respiratory distress syndrome may increase permeability in extra-alveolar or capillary vascular segments, resulting in different pathophysiological sequela.

A cross-site comparison of methods used for hydrogeologic characterization of the Galena-Platteville aquifer in Illinois and Wisconsin, with examples from selected Superfund sites

USGS Publications Warehouse

Kay, Robert T.; Mills, Patrick C.; Dunning, Charles P.; Yeskis, Douglas J.; Ursic, James R.; Vendl, Mark

2004-01-01

The effectiveness of 28 methods used to characterize the fractured Galena-Platteville aquifer at eight sites in northern Illinois and Wisconsin is evaluated. Analysis of government databases, previous investigations, topographic maps, aerial photographs, and outcrops was essential to understanding the hydrogeology in the area to be investigated. The effectiveness of surface-geophysical methods depended on site geology. Lithologic logging provided essential information for site characterization. Cores were used for stratigraphy and geotechnical analysis. Natural-gamma logging helped identify the effect of lithology on the location of secondary- permeability features. Caliper logging identified large secondary-permeability features. Neutron logs identified trends in matrix porosity. Acoustic-televiewer logs identified numerous secondary-permeability features and their orientation. Borehole-camera logs also identified a number of secondary-permeability features. Borehole ground-penetrating radar identified lithologic and secondary-permeability features. However, the accuracy and completeness of this method is uncertain. Single-point-resistance, density, and normal resistivity logs were of limited use. Water-level and water-quality data identified flow directions and indicated the horizontal and vertical distribution of aquifer permeability and the depth of the permeable features. Temperature, spontaneous potential, and fluid-resistivity logging identified few secondary-permeability features at some sites and several features at others. Flowmeter logging was the most effective geophysical method for characterizing secondary-permeability features. Aquifer tests provided insight into the permeability distribution, identified hydraulically interconnected features, the presence of heterogeneity and anisotropy, and determined effective porosity. Aquifer heterogeneity prevented calculation of accurate hydraulic properties from some tests. Different methods, such as flowmeter logging and slug testing, occasionally produced different interpretations. Aquifer characterization improved with an increase in the number of data points, the period of data collection, and the number of methods used.

Hyper-Cross-Linked Additives that Impede Aging and Enhance Permeability in Thin Polyacetylene Films for Organic Solvent Nanofiltration.

PubMed

Cheng, Xi Quan; Konstas, Kristina; Doherty, Cara M; Wood, Colin D; Mulet, Xavier; Xie, Zongli; Ng, Derrick; Hill, Matthew R; Shao, Lu; Lau, Cher Hon

2017-04-26

Membrane materials with high permeability to solvents while rejecting dissolved contaminants are crucial to lowering the energy costs associated with liquid separations. However, the current lack of stable high-permeability materials require innovative engineering solutions to yield high-performance, thin membranes using stable polymers with low permeabilities. Poly[1-(trimethylsilyl)-1-propyne] (PTMSP) is one of the most permeable polymers but is extremely susceptible to physical aging. Despite recent developments in anti-aging polymer membranes, this research breakthrough has yet to be demonstrated on thin PTMSP films supported on porous polymer substrates, a crucial step toward commercializing anti-aging membranes for industrial applications. Here we report the development of scalable, thin film nanocomposite membranes supported on polymer substrates that are resistant to physical aging while having high permeabilities to alcohols. The selective layer is made up of PTMSP and nanoporous polymeric additives. The nanoporous additives provide additional passageways to solvents, enhancing the high permeability of the PTMSP materials further. Through intercalation of polyacetylene chains into the sub-nm pores of organic additives, physical aging in the consequent was significantly hindered in continuous long-term operation. Remarkably we also demonstrate that the additives enhance both membrane permeability and rejection of dissolved contaminants across the membranes, as ethanol permeability at 5.5 × 10 -6 L m m -2 h -1 bar -1 with 93% Rose Bengal (1017.6 g mol -1 ) rejection, drastically outperforming commercial and state-of-the-art membranes. These membranes can replace energy-intensive separation processes such as distillation, lowering operation costs in well-established pharmaceutical production processes.

Properties of the moon and its environment from lunar magnetometer measurements

NASA Technical Reports Server (NTRS)

Parkin, C. W.

1976-01-01

Lunar analysis of data from a total of nine lunar magnetometers is described. Results obtained concerning electromagnetic, compositional, and structural properties of the lunar interior are discussed. Specific topics covered include: lunar magnetic permeability and iron abundance; limits on a highly conducting lunar core; lunar electrical conductivity; and internal structure inferred from conductivity and permeability results.

Method for the preparation of high surface area high permeability carbons

DOEpatents

Lagasse, R.R.; Schroeder, J.L.

1999-05-11

A method for preparing carbon materials having high surface area and high macropore volume to provide high permeability. These carbon materials are prepared by dissolving a carbonizable polymer precursor, in a solvent. The solution is cooled to form a gel. The solvent is extracted from the gel by employing a non-solvent for the polymer. The non-solvent is removed by critical point drying in CO{sub 2} at an elevated pressure and temperature or evaporation in a vacuum oven. The dried product is heated in an inert atmosphere in a first heating step to a first temperature and maintained there for a time sufficient to substantially cross-link the polymer material. The cross-linked polymer material is then carbonized in an inert atmosphere. 3 figs.

Optimal viscous damping of vibrating porous cylinders

NASA Astrophysics Data System (ADS)

Jafari Kang, Saeed; Masoud, Hassan

2017-11-01

We theoretically study small-amplitude oscillations of permeable cylinders immersed in an unbounded fluid. Specifically, we examine the effects of permeability and oscillation frequency on the damping coefficient, which is proportional to the power required to sustain the vibrations. Cylinders of both circular and non-circular cross-sections undergoing transverse and rotational vibrations are considered. Our calculations indicate that the damping coefficient often varies non-monotonically with the permeability. Depending on the oscillation period, the maximum damping of a permeable cylinder can be many times greater than that of an otherwise impermeable one. This might seem counter-intuitive at first since generally the power it takes to steadily drag a permeable object through the fluid is less than the power needed to drive the steady motion of the same but impermeable object. However, the driving power (or damping coefficient) for oscillating bodies is determined by not only the amplitude of the cyclic fluid force experienced by them but also by the phase shift between the force and their periodic motion. An increase in the latter is responsible for excess damping coefficient of vibrating porous cylinders.

How Students View the Boundaries Between Their Science and Religious Education Concerning the Origins of Life and the Universe.

PubMed

Billingsley, Berry; Brock, Richard; Taber, Keith S; Riga, Fran

2016-05-01

Internationally in secondary schools, lessons are typically taught by subject specialists, raising the question of how to accommodate teaching which bridges the sciences and humanities. This is the first study to look at how students make sense of the teaching they receive in two subjects (science and religious education [RE]) when one subject's curriculum explicitly refers to cross-disciplinary study and the other does not. Interviews with 61 students in seven schools in England suggested that students perceive a permeable boundary between science and their learning in science lessons and also a permeable boundary between religion and their learning in RE lessons, yet perceive a firm boundary between science lessons and RE lessons. We concluded that it is unreasonable to expect students to transfer instruction about cross-disciplinary perspectives across such impermeable subject boundaries. Finally, we consider the implications of these findings for the successful management of cross-disciplinary education.

Development of bioactive coatings based on γ-irradiated proteins to preserve strawberries

NASA Astrophysics Data System (ADS)

Vu, K. D.; Hollingsworth, R. G.; Salmieri, S.; Takala, P. N.; Lacroix, M.

2012-08-01

Gamma irradiation was applied for creating cross-linked proteins to enhance the physicochemical properties of edible films made of calcium caseinate, whey protein isolate and glycerol. The characteristics of γ irradiated cross-linked proteins were analyzed by Fourier Transform Infrared spectroscopy. A second derivative spectra exhibited changes in band intensities that were correlated to an increase of β-sheet structure and a decrease of α-helix and unordered fractions of γ irradiated-cross-linked proteins as compared to the control without irradiation. Furthermore, on addition of methylcellulose to the irradiated protein matrix it was found that it has potential in enhancing the puncture strength and has no detrimental effect on water vapor permeability of protein based films. Finally, these film formulations were used as bioactive edible coatings containing natural antimicrobial agents (limonene and peppermint) to preserve the shelf life of fresh strawberries during storage. The bioactive coatings containing peppermint was found to be more efficient as preserving coatings than the formulations containing limonene. Irradiated proteins/methylcellulose/peppermint formulation had only 40% of decay at day 8 while it was 65% for the control.

Bacterial DNA induces pulmonary damage via TLR-9 through cross-talk with neutrophils.

PubMed

Itagaki, Kiyoshi; Adibnia, Yasaman; Sun, Shiqin; Zhao, Cong; Sursal, Tolga; Chen, Yu; Junger, Wolfgang; Hauser, Carl J

2011-12-01

Bacterial DNA (bDNA) contains hypomethylated "CpG" repeats that can be recognized by Toll-like receptor 9 (TLR-9) as a pathogen-associated molecular pattern. The ability of bDNA to initiate lung injury via TLR-9 has been inferred on the basis of studies using artificial CpG DNA. But the role of authentic bDNA in lung injury is still unknown. Moreover, the mechanisms by which CpG DNA species can lead to pulmonary injury are unknown, although neutrophils (PMNs) are thought to play a key role in the genesis of septic acute lung injury. We evaluated the effects of bDNA on PMN-endothelial cell (EC) interactions thought critical for initiation of acute lung injury. Using a biocapacitance system to monitor real-time changes in endothelial permeability, we demonstrate here that bDNA causes EC permeability in a dose-dependent manner uniquely in the presence of PMNs. These permeability changes are inhibited by chloroquine, suggesting TLR-9 dependency. When PMNs were preincubated with bDNA and applied to ECs or when bDNA was applied to ECs without PMNs, no permeability changes were detected. To study the underlying mechanisms, we evaluated the effects of bDNA on PMN-EC adherence. Bacterial DNA significantly increased PMN adherence to ECs in association with upregulated adhesion molecules in both cell types. Taken together, our results strongly support the conclusion that bDNA can initiate lung injury by stimulating PMN-EC adhesive interactions predisposing to endothelial permeability. Bacterial DNA stimulation of TLR-9 appears to promote enhanced gene expression of adhesion molecules in both cell types. This leads to PMN-EC cross-talk, which is required for injury to occur.

Grain-Size Dynamics Beneath Mid-Ocean Ridges: Implications for Permeability and Melt Extraction

NASA Astrophysics Data System (ADS)

Turner, A. J.; Katz, R. F.; Behn, M. D.

2014-12-01

The permeability structure of the sub-ridge mantle plays an important role in how melt is focused and extracted at mid-ocean ridges. Permeability is controlled by porosity and the grain size of the solid mantle matrix, which is in turn controlled by the deformation conditions. To date, models of grain size evolution and mantle deformation have not been coupled to determine the influence of spatial variations in grain-size on the permeability structure at mid-ocean ridges. Rather, current models typically assume a constant grain size for the whole domain [1]. Here, we use 2-D numerical models to evaluate the influence of grain-size variability on the permeability structure beneath a mid-ocean ridge and use these results to speculate on the consequences for melt focusing and extraction. We construct a two-dimensional, single phase model for the steady-state grain size beneath a mid-ocean ridge. The model employs a composite rheology of diffusion creep, dislocation creep, dislocation accommodated grain boundary sliding, and a brittle stress limiter. Grain size is calculated using the "wattmeter" model of Austin and Evans [2]. We investigate the sensitivity of the model to global variations in grain growth exponent, potential temperature, spreading-rate, and grain boundary sliding parameters [3,4]. Our model predicts that permeability varies by two orders of magnitude due to the spatial variability of grain size within the expected melt region of a mid-ocean ridge. The predicted permeability structure suggests grain size may promote focusing of melt towards the ridge axis. Furthermore, the calculated grain size structure should focus melt from a greater depth than models that exclude grain-size variability. Future work will involve evaluating this hypothesis by implementing grain-size dynamics within a two-phase mid-ocean ridge model. The developments of such a model will be discussed. References: [1] R. F. Katz, Journal of Petrology, volume 49, issue 12, page 2099, 2008. [2] N. J. Austin and B. Evans, Geology, 35:354, 2007. [3] G. Hirth and D. Kohlstedt, In Inside the Subduction Factory, volume 138 of AGU Geophysical Monograph, 2003. [4] L. N. Hansen et al., JGR (Solid Earth), 116:B08201, 2011.

Assessment of porous material anisotropy and its effect on gas permeability

NASA Astrophysics Data System (ADS)

Wałowski, Grzegorz

2017-10-01

The results of experimental research upon the assessment of porous material anisotropy and its effect on gas permeability of porous materials with respect to the gas flow. The conducted research applied to natural materials with an anisotropic gap-porous structure and - for comparative purposes - to model materials such as coke, pumice and polyamide agglomerates. The research was conducted with the use of a special test stand that enables measuring the gas permeability with respect to three flow orientations compared with symmetric cubic-shaped samples. The research results show an explicit impact of the flow direction on the permeability of materials porous, which results from their anisotropic internal structures. The anisotropy coefficient and permeability effective coefficient of such materials was determined and an experimental evaluation of the value of this coefficient was conducted with respect to the gas stream and the total pressure drop across the porous deposit. The process of gas permeability was considered in the category of hydrodynamics of gas flow through porous deposits. It is important to broaden the knowledge of gas hydrodynamics assessment in porous media so far unrecognised for the development of a new generation of clean energy sources, especially in the context of biogas or raw gas production.

Dynamic permeability of the lacunar–canalicular system in human cortical bone

PubMed Central

Benalla, M.; Palacio-Mancheno, P. E.; Fritton, S. P.; Cardoso, L.

2013-01-01

A new method for the experimental determination of the permeability of a small sample of a fluid-saturated hierarchically structured porous material is described and applied to the determination of the lacunar–canalicular permeability (KLC) in bone. The interest in the permeability of the lacunar–canalicular pore system (LCS) is due to the fact that the LCS is considered to be the site of bone mechanotransduction due to the loading-driven fluid flow over cellular structures. The permeability of this space has been estimated to be anywhere from 10−17 to 10−25 m2. However, the vascular pore system and LCS are intertwined, rendering the permeability of the much smaller-dimensioned LCS challenging to measure. In this study, we report a combined experimental and analytical approach that allowed the accurate determination of the KLC to be on the order of 10−22 m2 for human osteonal bone. It was found that the KLC has a linear dependence on loading frequency, decreasing at a rate of 2 × 10−24 m2/Hz from 1 to 100 Hz, and using the proposed model, the porosity alone was able to explain 86 % of the KLC variability. PMID:24146291

Cholesterol effect on water permeability through DPPC and PSM lipid bilayers: a molecular dynamics study.

PubMed

Saito, Hiroaki; Shinoda, Wataru

2011-12-29

Water permeability of two different lipid bilayers of dipalmitoylphosphatidylcholine (DPPC) and palmitoylsphingomyelin (PSM) in the absence and presence of cholesterol (0-50 mol %) have been studied by molecular dynamics simulations to elucidate the molecular mechanism of the reduction in water leakage across the membranes by the addition of cholesterol. An enhanced free energy barrier was observed in these membranes with increased cholesterol concentration, and this was explained by the reduced cavity density around the cholesterol in the hydrophobic membrane core. There was an increase of trans conformers in the hydrophobic lipid chains adjacent to the cholesterol, which reduced the cavity density. The enhanced free energy barrier was found to be the main reason to reduce the water permeability with increased cholesterol concentration. At low cholesterol concentrations the PSM bilayer exhibited a higher free energy barrier than the DPPC bilayer for water permeation, while at greater than 30 mol % of cholesterol the difference became minor. This tendency for the PSM and DPPC bilayers to resemble each other at higher cholesterol concentrations was similar to commonly observed trends in several structural properties, such as order parameters, cross-sectional area per molecule, and cavity density profiles in the hydrophobic regions of bilayer membranes. These results demonstrate that DPPC and PSM bilayers with high cholesterol contents possess similar physical properties, which suggests that the solubility of cholesterol in these lipid bilayers has importance for an understanding of multicomponent lipid membranes with cholesterol. © 2011 American Chemical Society

Doxycycline Attenuates Lipopolysaccharide-Induced Microvascular Endothelial Cell Derangements.

PubMed

Wiggins-Dohlvik, Katie; Stagg, Hayden W; Han, Min Suk; Alluri, Himakarnika; Oakley, Ryan P; Anasooya Shaji, Chinchusha; Davis, Matthew L; Tharakan, Binu

2016-06-01

Lipopolysaccharide (LPS) is known to induce vascular derangements. The pathophysiology involved therein is unknown, but matrix metalloproteinases (MMPs) may be an important mediator. We hypothesized that in vitro LPS provokes vascular permeability, damages endothelial structural proteins, and increases MMP activity; that in vivo LPS increases permeability and fluid requirements; and that the MMP inhibitor doxycycline mitigates such changes. Rat lung microvascular endothelial cells were divided into four groups: control, LPS, LPS plus doxycycline, and doxycycline. Permeability, structural proteins β-catenin and Filamentous-actin, and MMP-9 activity were examined. Sprauge Dawley rats were divided into sham, IV LPS, and IV LPS plus IV doxycycline groups. Mesenteric postcapillary venules were observed. Blood pressure was measured as animals were resuscitated and fluid requirements were compared. Statistical analysis was conducted using Student's t-test and ANOVA. In vitro LPS increased permeability, damaged adherens junctions, induced actin stress fiber formation, and increased MMP-9 enzyme activity. In vivo, IV LPS administration induced vascular permeability. During resuscitation, significantly more fluid was necessary to maintain normotension in the IV LPS group. Doxycycline mitigated all derangements observed. We conclude that LPS increases permeability, damages structural proteins, and increases MMP-9 activity in endothelial cells. Additionally, endotoxemia induces hyperpermeability and increases the amount of IV fluid required to maintain normotension in vivo. Doxycycline mitigates such changes both in vitro and in vivo. Our findings illuminate the possible role of matrix metalloproteinases in the pathophysiology of lipopolysaccharide-induced microvascular hyperpermeability and pave the way for better understanding and treatment of this process.

Permeability estimations and frictional flow features passing through porous media comprised of structured microbeads

NASA Astrophysics Data System (ADS)

Shin, C.

2017-12-01

Permeability estimation has been extensively researched in diverse fields; however, methods that suitably consider varying geometries and changes within the flow region, for example, hydraulic fracture closing for several years, are yet to be developed. Therefore, in the present study a new permeability estimation method is presented based on the generalized Darcy's friction flow relation, in particular, by examining frictional flow parameters and characteristics of their variations. For this examination, computational fluid dynamics (CFD) simulations of simple hydraulic fractures filled with five layers of structured microbeads and accompanied by geometry changes and flow transitions are performed. Consequently, it was checked whether the main structures and shapes of each flow path are preserved, even for geometry variations within porous media. However, the scarcity and discontinuity of streamlines increase dramatically in the transient- and turbulent-flow regions. The quantitative and analytic examinations of the frictional flow features were also performed. Accordingly, the modified frictional flow parameters were successfully presented as similarity parameters of porous flows. In conclusion, the generalized Darcy's friction flow relation and friction equivalent permeability (FEP) equation were both modified using the similarity parameters. For verification, the FEP values of the other aperture models were estimated and then it was checked whether they agreed well with the original permeability values. Ultimately, the proposed and verified method is expected to efficiently estimate permeability variations in porous media with changing geometric factors and flow regions, including such instances as hydraulic fracture closings.

Effects of biofilm on flow over and through a permeable bed

NASA Astrophysics Data System (ADS)

Kazemifar, Farzan; Blois, Gianluca; Aybar, Marcelo; Perez-Calleja, Patricia; Nerenberg, Robert; Sinha, Sumit; Hardy, Richard; Best, James; Sambrook-Smith, Gregory; Christensen, Kenneth

2016-11-01

Biofilms constitute an important form of bacterial life in aquatic environments and are present at the interface of fluids and solids, such as riverbeds. Biofilms are permeable, heterogeneous, and deformable structures that can influence the flow and mass/momentum transport, yet their interaction with flow is not fully understood in part due to technical obstacles impeding quantitative experimental investigations. The porosity of river beds results in the generation of a diverse mosaic of 'suction' and 'ejection' events that are far removed from typical assumptions of turbulent flow structure over an impermeable bed. In this work, the effect of biofilm on bed permeability is studied. Experiments are conducted in a closed water channel equipped with 4-cm-deep permeable bed models consisting of horizontal cylinders normal to the bulk flow direction, forming an idealized two-dimensional permeable bed. Prior to conducting flow experiments, the models are placed within an independent biofilm reactor to initiate and control the biofilm growth. Once a targeted biofilm growth stage is achieved, the models are transferred to the water channel and subjected to transitional and turbulent flows. Long-distance microscopic particle image velocimetry measurements are performed to quantify the effect of biofilm on the turbulence structure of the free flow as well as the freestream-subsurface flow interaction.

Effects of biofilm on flow over and through a permeable bed

NASA Astrophysics Data System (ADS)

Kazemifar, F.; Blois, G.; Aybar, M.; Perez Calleja, P.; Nerenberg, R.; Sinha, S.; Hardy, R. J.; Best, J.; Sambrook Smith, G.; Christensen, K. T.

2016-12-01

Biofilms constitute an important form of bacterial life in aquatic environments and are present at the fluid-solid interfaces, such as riverbeds. Biofilms are permeable, heterogeneous, and deformable structures that can influence the flow and mass/momentum transport, yet their interaction with flow is not fully understood in part due to technical obstacles impeding quantitative experimental investigations. The porosity of river beds results in the generation of a diverse mosaic of `suction' and `ejection' events that are far removed from typical assumptions of turbulent flow structure over an impermeable bed. In this work, the effect of biofilm on bed permeability is studied. Experiments are conducted in a closed water channel equipped with 4-cm-deep permeable bed models consisting of horizontal cylinders normal to the bulk flow direction, forming an idealized two-dimensional permeable bed (Figure 1). Prior to conducting flow experiments, the models are placed within an independent biofilm reactor to initiate and accurately control the biofilm growth. Once a targeted biofilm growth stage is achieved, the models are transferred to the water channel and subjected to transitional and turbulent flows. Long-distance microscopic particle image velocimetry measurements are performed to quantify the effect of biofilm on the turbulence structure of the free flow as well as the freestream-subsurface flow interaction.

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

Heath, Jason E.; Bauer, Stephen J.; Broome, Scott Thomas

The Iowa Stored Energy Plant Agency selected a geologic structure at Dallas Center, Iowa, for evaluation of subsurface compressed air energy storage. The site was rejected due to lower-than-expected and heterogeneous permeability of the target reservoir, lower-than-desired porosity, and small reservoir volume. In an initial feasibility study, permeability and porosity distributions of flow units for the nearby Redfield gas storage field were applied as analogue values for numerical modeling of the Dallas Center Structure. These reservoir data, coupled with an optimistic reservoir volume, produced favorable results. However, it was determined that the Dallas Center Structure cannot be simplified to fourmore » zones of high, uniform permeabilities. Updated modeling using field and core data for the site provided unfavorable results for air fill-up. This report presents Sandia National Laboratories petrologic and petrophysical analysis of the Dallas Center Structure that aids in understanding why the site was not suitable for gas storage.« less

Low Permeability Oil and Gas Plays

EIA Publications

The map shows boundaries, structure (elevation of the top contours), and isopachs (thickness contours) for major low permeability oil and gas plays in the lower 48 States. Additionally, related oil and gas infrastructure layers are included

Validation of an immortalized human (hBMEC) in vitro blood-brain barrier model.

PubMed

Eigenmann, Daniela Elisabeth; Jähne, Evelyn Andrea; Smieško, Martin; Hamburger, Matthias; Oufir, Mouhssin

2016-03-01

We recently established and optimized an immortalized human in vitro blood-brain barrier (BBB) model based on the hBMEC cell line. In the present work, we validated this mono-culture 24-well model with a representative series of drug substances which are known to cross or not to cross the BBB. For each individual compound, a quantitative UHPLC-MS/MS method in Ringer HEPES buffer was developed and validated according to current regulatory guidelines, with respect to selectivity, precision, and reliability. Various biological and analytical challenges were met during method validation, highlighting the importance of careful method development. The positive controls antipyrine, caffeine, diazepam, and propranolol showed mean endothelial permeability coefficients (P e) in the range of 17-70 × 10(-6) cm/s, indicating moderate to high BBB permeability when compared to the barrier integrity marker sodium fluorescein (mean P e 3-5 × 10(-6) cm/s). The negative controls atenolol, cimetidine, and vinblastine showed mean P e values < 10 × 10(-6) cm/s, suggesting low permeability. In silico calculations were in agreement with in vitro data. With the exception of quinidine (P-glycoprotein inhibitor and substrate), BBB permeability of all control compounds was correctly predicted by this new, easy, and fast to set up human in vitro BBB model. Addition of retinoic acid and puromycin did not increase transendothelial electrical resistance (TEER) values of the BBB model.

Sharp Permeability Transitions due to Shallow Diagenesis of Subduction Zone Sediments

NASA Astrophysics Data System (ADS)

James, S.; Screaton, E.

2013-12-01

The permeability of hemipelagic sediments is an important factor in fluid flow in subduction zones and can be affected by porosity changes and cementation-dissolution processes acting during diagenesis. Anomalously high porosities have been observed in cores from the Shikoku Basin sediments approaching the Nankai Trough subduction zone. These high porosities have been attributed to the presence of minor amounts of amorphous silica cement that strengthen the sediment and inhibit consolidation. The porosity rapidly drops from 66-68% to 54-56% at a diagenetic boundary where the amorphous silica cement dissolves. Although the anomalous porosity profiles at Nankai have received attention, the magnitude of the corresponding permeability change has not been addressed. In this study, permeability profiles were constructed using permeability-porosity relationships from previous studies, to estimate the magnitude and rate of permeability changes with depth. The predicted permeability profiles for the Nankai Trough sediment cores indicate that permeability drops by almost one order of magnitude across the diagenetic boundary. This abrupt drop in permeability has the potential to facilitate significant changes in pore fluid pressures and thus to influence the deformation of the sediment onto the accretionary prism. At the Costa Rica subduction zone, results vary with location. Site U1414 offshore the Osa Peninsula shows porosities stable at 69% above 145 mbsf and then decrease to 54% over a 40 m interval. A porosity drop of that magnitude is predicted to correlate to an order of magnitude permeability decrease. In contrast, porosity profiles from Site 1039 offshore the Nicoya Peninsula and Site U1381 offshore the Osa Peninsula show anomalously high porosities but no sharp drop. It is likely that sediments do not cross the diagenetic boundary due to the extremely low (<10°C/km) thermal gradient at Site 1039 and the thin (<100 m) sediment cover at Site U1381. At these locations, the porosity loss and permeability reduction may occur after the sediment is subducted and contribute to high pore pressures at the plate boundary.

Cross-over endocytosis of claudins is mediated by interactions via their extracellular loops.

PubMed

Gehne, Nora; Lamik, Agathe; Lehmann, Martin; Haseloff, Reiner F; Andjelkovic, Anuska V; Blasig, Ingolf E

2017-01-01

Claudins (Cldns) are transmembrane tight junction (TJ) proteins that paracellularly seal endo- and epithelial barriers by their interactions within the TJs. However, the mechanisms allowing TJ remodeling while maintaining barrier integrity are largely unknown. Cldns and occludin are heterophilically and homophilically cross-over endocytosed into neighboring cells in large, double membrane vesicles. Super-resolution microscopy confirmed the presence of Cldns in these vesicles and revealed a distinct separation of Cldns derived from opposing cells within cross-over endocytosed vesicles. Colocalization of cross-over endocytosed Cldn with the autophagosome markers as well as inhibition of autophagosome biogenesis verified involvement of the autophagosomal pathway. Accordingly, cross-over endocytosed Cldns underwent lysosomal degradation as indicated by lysosome markers. Cross-over endocytosis of Cldn5 depended on clathrin and caveolin pathways but not on dynamin. Cross-over endocytosis also depended on Cldn-Cldn-interactions. Amino acid substitutions in the second extracellular loop of Cldn5 (F147A, Q156E) caused impaired cis- and trans-interaction, as well as diminished cross-over endocytosis. Moreover, F147A exhibited an increased mobility in the membrane, while Q156E was not as mobile but enhanced the paracellular permeability. In conclusion, the endocytosis of TJ proteins depends on their ability to interact strongly with each other in cis and trans, and the mobility of Cldns in the membrane is not necessarily an indicator of barrier permeability. TJ-remodeling via cross-over endocytosis represents a general mechanism for the degradation of transmembrane proteins in cell-cell contacts and directly links junctional membrane turnover to autophagy.

Permeability and strength structure around an ancient exhumed subduction-zone fault

NASA Astrophysics Data System (ADS)

Kato, A.; Sakaguchi, A.; Yoshida, S.; Kaneda, Y.

2003-12-01

Investigating the transporting properties of subduction zone faults is crucial for understanding shear strength and slip-stability, or instability, of subduction zone faults. Despite the influence of pore pressure on a wide range of subduction-zone fault processes, few previous studies have evaluated the permeability structure around the fault placed in a well-defined structural context. In this study, the aim is to gain the entire permeability and the shear strength structure around the ancient subduction zone fault. We have conducted a series of permeability measurements and shear failure experiments in seismogenic environments using intact rocks sampled at the outcrop of an exhumed fault zone in the Cretaceous Shimanto accretionary complex, in Shikoku, SW Japan, where a typical evidence for seismic fault rock of pseudotachylyte has been demonstrated [Ikesawa et al., 2003]. This fault zone is located at boundary between the sandstone-dominant coherent unit of the Nonokawa Formation and the Okitsu mélange. The porosity of each rock sample is less than 1 %, except for the shear zone. Cylindrical test specimens (length = 40 mm, diameter = 20 mm) were cored to an accuracy of within 0.02 mm. Most of values of permeability were evaluated at confining pressure Pc of 140 MPa and pore pressure Pp of 115 MPa simulating the depth of 5 km (suprahydrostatic pore pressure). It is found that the permeability at room temperature shows the heterogeneous structure across the fault zone. The permeability of sandstone-dominant coherent unit is the lowest (10-19 m2) across the fault zone. In contrast, high shear zone has the highest permeability (10-16 m2). Following the increase in temperature, permeability evolution has been investigated. The permeability at 250oC continuously decreases with hold time for all types of rock specimens, and the reduction rate of permeability against hold time seems to become small with hold time. It seems that the reduction rate does not significantly depend on the rock types. The specimen was loaded at a strain rate of 2*E-6 /s under the conditions (Pc, Pp, T) = (140 MPa, 105 MPa, 250oC) to conduct the shear fracture experiments. High shear zone has a minimum value in strength profile. In contrast, the largest shear strength is observed at sandstone in coherent unit. From the seismic reflection surveys in the Nankai Trough, Park et al. [2002] delineated reflections with negative polarities beneath the Nankai accretionary prism 20-60 km landward of the frontal thrust, which are located deeper than the negative polarity décollement near the frontal thrust. They interpreted that the DSRs indicate the elevated fluid pressures. The fault zone studied in this paper is consistent with the duplex-model, and corresponds to the area where the décollement near the frontal thrust stepped down. Present results show the possibility that the coherent sandstone acts as a cap rock for fluid flow, and shear zone as a conduit for the flow, which leads to the elevated pore pressures along the roof thrust.

[Correlation of substrate structure and hydraulic characteristics in subsurface flow constructed wetlands].

PubMed

Bai, Shao-Yuan; Song, Zhi-Xin; Ding, Yan-Li; You, Shao-Hong; He, Shan

2014-02-01

The correlation of substrate structure and hydraulic characteristics was studied by numerical simulation combined with experimental method. The numerical simulation results showed that the permeability coefficient of matrix had a great influence on hydraulic efficiency in subsurface flow constructed wetlands. The filler with a high permeability coefficient had a worse flow field distribution in the constructed wetland with single layer structure. The layered substrate structure with the filler permeability coefficient increased from surface to bottom could avoid the short-circuited flow and dead-zones, and thus, increased the hydraulic efficiency. Two parallel pilot-scale constructed wetlands were built according to the numerical simulation results, and tracer experiments were conducted to validate the simulation results. The tracer experiment result showed that hydraulic characteristics in the layered constructed wetland were obviously better than that in the single layer system, and the substrate effective utilization rates were 0.87 and 0.49, respectively. It was appeared that numerical simulation would be favorable for substrate structure optimization in subsurface flow constructed wetlands.

Using flowmeter pulse tests to define hydraulic connections in the subsurface: A fractured shale example

USGS Publications Warehouse

Williams, J.H.; Paillet, Frederick L.

2002-01-01

Cross-borehole flowmeter pulse tests define subsurface connections between discrete fractures using short stress periods to monitor the propagation of the pulse through the flow system. This technique is an improvement over other cross-borehole techniques because measurements can be made in open boreholes without packers or previous identification of water-producing intervals. The method is based on the concept of monitoring the propagation of pulses rather than steady flow through the fracture network. In this method, a hydraulic stress is applied to a borehole connected to a single, permeable fracture, and the distribution of flow induced by that stress monitored in adjacent boreholes. The transient flow responses are compared to type curves computed for several different types of fracture connections. The shape of the transient flow response indicates the type of fracture connection, and the fit of the data to the type curve yields an estimate of its transmissivity and storage coefficient. The flowmeter pulse test technique was applied in fractured shale at a volatile-organic contaminant plume in Watervliet, New York. Flowmeter and other geophysical logs were used to identify permeable fractures in eight boreholes in and near the contaminant plume using single-borehole flow measurements. Flowmeter cross-hole pulse tests were used to identify connections between fractures detected in the boreholes. The results indicated a permeable fracture network connecting many of the individual boreholes, and demonstrated the presence of an ambient upward hydraulic-head gradient throughout the site.

Three-scale analysis of the permeability of a natural shale

NASA Astrophysics Data System (ADS)

Davy, C. A.; Adler, P. M.

2017-12-01

The macroscopic permeability of a natural shale is determined by using structural measurements on three different scales. Transmission electron microscopy yields two-dimensional (2D) images with pixels smaller than 1 nm; these images are used to reconstruct 3D nanostructures. Three-dimensional focused ion beam-scanning electron microscopy (5.95- to 8.48-nm voxel size) provides 3D mesoscale pores of limited relative volume (1.71-5.9%). Micro-computed tomography (700-nm voxel size) provides information on the mineralogy of the shale, including the pores on this scale which do not percolate; synthetic 3D media are derived on the macroscopic scale by a training image technique. Permeability of the nanoscale, of the mesoscale structures and of their superposition is determined by solving the Stokes equation and this enables us to estimate the permeabilities of the 700-nm voxels located within the clay matrix. Finally, the Darcy equation is solved on synthetic 3D macroscale media to obtain the macroscopic permeability which is found in good agreement with experimental results obtained on the centimetric scale.

Low-permeability concretes containing slag and silica fume.

DOT National Transportation Integrated Search

1993-01-01

Chloride-induced corrosion causes significant deterioration in transportation structures where uncoated reinforcing steel is used. Concretes having a very low permeability are used to prevent the intrusion of chlorides into concrete to the level of t...

Superconducting magnet and fabrication method

NASA Technical Reports Server (NTRS)

Israelsson, Ulf E. (Inventor); Strayer, Donald M. (Inventor)

1994-01-01

A method of trapping a field in a block of superconductor material, includes providing (i) a block of material defining a bore, (ii) a high permeability core within the bore that defines a low reluctance path through the bore, (iii) a high permeability external structure on the exterior of the block of material that defines a low reluctance path between opposite ends of the core, and (iv) an electromagnet configured to apply a magnetic field around the high permeability core. The method proceeds by energizing the electromagnet to produce an applied magnetic field around the high permeability core, cooling the block of material sufficiently to render the block of material superconducting, de-energizing the electromagnet to result in a trapped magnetic field, and at least partially removing the low reluctance path defined by the core and the external structure in order to increase the magnetic flux density of the trapped magnetic field.

Modelling of hydrothermal fluid flow and structural architecture in an extensional basin, Ngakuru Graben, Taupo Rift, New Zealand

NASA Astrophysics Data System (ADS)

Kissling, W. M.; Villamor, P.; Ellis, S. M.; Rae, A.

2018-05-01

Present-day geothermal activity on the margins of the Ngakuru graben and evidence of fossil hydrothermal activity in the central graben suggest that a graben-wide system of permeable intersecting faults acts as the principal conduit for fluid flow to the surface. We have developed numerical models of fluid and heat flow in a regional-scale 2-D cross-section of the Ngakuru Graben. The models incorporate simplified representations of two 'end-member' fault architectures (one symmetric at depth, the other highly asymmetric) which are consistent with the surface locations and dips of the Ngakuru graben faults. The models are used to explore controls on buoyancy-driven convective fluid flow which could explain the differences between the past and present hydrothermal systems associated with these faults. The models show that the surface flows from the faults are strongly controlled by the fault permeability, the fault system architecture and the location of the heat source with respect to the faults in the graben. In particular, fault intersections at depth allow exchange of fluid between faults, and the location of the heat source on the footwall of normal faults can facilitate upflow along those faults. These controls give rise to two distinct fluid flow regimes in the fault network. The first, a regular flow regime, is characterised by a nearly unchanging pattern of fluid flow vectors within the fault network as the fault permeability evolves. In the second, complex flow regime, the surface flows depend strongly on fault permeability, and can fluctuate in an erratic manner. The direction of flow within faults can reverse in both regimes as fault permeability changes. Both flow regimes provide insights into the differences between the present-day and fossil geothermal systems in the Ngakuru graben. Hydrothermal upflow along the Paeroa fault seems to have occurred, possibly continuously, for tens of thousands of years, while upflow in other faults in the graben has switched on and off during the same period. An asymmetric graben architecture with the Paeroa being the major boundary fault will facilitate the predominant upflow along this fault. Upflow on the axial faults is more difficult to explain with this modelling. It occurs most easily with an asymmetric graben architecture and heat sources close to the graben axis (which could be associated with remnant heat from recent eruptions from Okataina Volcanic Centre). Temporal changes in upflow can also be associated with acceleration and deceleration of fault activity if this is considered a proxy for fault permeability. Other explanations for temporal variations in hydrothermal activity not explored here are different permeability on different faults, and different permeability along fault strike.

Influence of Pectin as a green polymer electrolyte on the transport properties of Chitosan-Pectin membranes.

PubMed

Pasini Cabello, S D; Ochoa, N A; Takara, E A; Mollá, S; Compañ, V

2017-02-10

Novel blend membranes have been prepared from Chitosan (CH), Pectin (PEC) and their mixtures. The obtained samples were cross-linked and sulfonated before characterization. The results show that CH/PEC membranes display structural changes on the chemical and physical properties as a function of composition. DSC analysis reveals an endothermic peak due to the scission of the ionic pairs between carboxylic groups and ammonium groups, which produces a strong change on physical properties such as methanol permeability and proton conductivity. The methanol permeability decreases with the amount of Pectin from (4.24±0.04)×10 -6 cm 2 /s for pure Chitosan membrane to (1.51±0.03)×10 -6 cm 2 /s for blend CH/PEC membranes when the amount of Pectin is 50% (v/v). The proton conductivities of the blend membranes follow a similar behavior. For a pure CH membrane the conductivity is 2.44×10 -3 S/cm, decreasing with pectin content until the composition 50/50 (v/v), in which the conductivity drops almost one order of magnitude. Copyright © 2016 Elsevier Ltd. All rights reserved.

Flt1/VEGFR1 heterozygosity causes transient embryonic edema.

PubMed

Otowa, Yasunori; Moriwaki, Kazumasa; Sano, Keigo; Shirakabe, Masanori; Yonemura, Shigenobu; Shibuya, Masabumi; Rossant, Janet; Suda, Toshio; Kakeji, Yoshihiro; Hirashima, Masanori

2016-06-02

Vascular endothelial growth factor-A is a major player in vascular development and a potent vascular permeability factor under physiological and pathological conditions by binding to a decoy receptor Flt1 and its primary receptor Flk1. In this study, we show that Flt1 heterozygous (Flt1(+/-)) mouse embryos grow up to adult without life-threatening abnormalities but exhibit a transient embryonic edema around the nuchal and back regions, which is reminiscent of increased nuchal translucency in human fetuses. Vascular permeability is enhanced and an intricate infolding of the plasma membrane and huge vesicle-like structures are seen in Flt1(+/-) capillary endothelial cells. Flk1 tyrosine phosphorylation is elevated in Flt1(+/-) embryos, but Flk1 heterozygosity does not suppress embryonic edema caused by Flt1 heterozygosity. When Flt1 mutants are crossed with Aspp1(-/-) mice which exhibit a transient embryonic edema with delayed formation and dysfunction of lymphatic vessels, only 5.7% of Flt1(+/-); Aspp1(-/-) mice survive, compared to expected ratio (25%). Our results demonstrate that Flt1 heterozygosity causes a transient embryonic edema and can be a risk factor for embryonic lethality in combination with other mutations causing non-lethal vascular phenotype.

Collagen-based brain microvasculature model in vitro using three-dimensional printed template

PubMed Central

Kim, Jeong Ah; Kim, Hong Nam; Im, Sun-Kyoung; Chung, Seok

2015-01-01

We present an engineered three-dimensional (3D) in vitro brain microvasculature system embedded within the bulk of a collagen matrix. To create a hydrogel template for the functional brain microvascular structure, we fabricated an array of microchannels made of collagen I using microneedles and a 3D printed frame. By culturing mouse brain endothelial cells (bEnd.3) on the luminal surface of cylindrical collagen microchannels, we reconstructed an array of brain microvasculature in vitro with circular cross-sections. We characterized the barrier function of our brain microvasculature by measuring transendothelial permeability of 40 kDa fluorescein isothiocyanate-dextran (Stoke's radius of ∼4.5 nm), based on an analytical model. The transendothelial permeability decreased significantly over 3 weeks of culture. We also present the disruption of the barrier function with a hyperosmotic mannitol as well as a subsequent recovery over 4 days. Our brain microvasculature model in vitro, consisting of system-in-hydrogel combined with the widely emerging 3D printing technique, can serve as a useful tool not only for fundamental studies associated with blood-brain barrier in physiological and pathological settings but also for pharmaceutical applications. PMID:25945141

Effect of Laminating Pressure on Polymeric Multilayer Nanofibrous Membranes for Liquid Filtration.

PubMed

Yalcinkaya, Fatma; Hruza, Jakub

2018-04-24

In the new century, electrospun nanofibrous webs are widely employed in various applications due to their specific surface area and porous structure with narrow pore size. The mechanical properties have a major influence on the applications of nanofiber webs. Lamination technology is an important method for improving the mechanical strength of nanofiber webs. In this study, the influence of laminating pressure on the properties of polyacrylonitrile (PAN) and polyvinylidene fluoride (PVDF) nanofibers/laminate was investigated. Heat-press lamination was carried out at three different pressures, and the surface morphologies of the multilayer nanofibrous membranes were observed under an optical microscope. In addition, air permeability, water filtration, and contact angle experiments were performed to examine the effect of laminating pressure on the breathability, water permeability and surface wettability of multilayer nanofibrous membranes. A bursting strength test was developed and applied to measure the maximum bursting pressure of the nanofibers from the laminated surface. A water filtration test was performed using a cross-flow unit. Based on the results of the tests, the optimum laminating pressure was determined for both PAN and PVDF multilayer nanofibrous membranes to prepare suitable microfilters for liquid filtration.

Impact of geometrical properties on permeability and fluid phase distribution in porous media

NASA Astrophysics Data System (ADS)

Lehmann, P.; Berchtold, M.; Ahrenholz, B.; Tölke, J.; Kaestner, A.; Krafczyk, M.; Flühler, H.; Künsch, H. R.

2008-09-01

To predict fluid phase distribution in porous media, the effect of geometric properties on flow processes must be understood. In this study, we analyze the effect of volume, surface, curvature and connectivity (the four Minkowski functionals) on the hydraulic conductivity and the water retention curve. For that purpose, we generated 12 artificial structures with 800 3 voxels (the units of a 3D image) and compared them with a scanned sand sample of the same size. The structures were generated with a Boolean model based on a random distribution of overlapping ellipsoids whose size and shape were chosen to fulfill the criteria of the measured functionals. The pore structure of sand material was mapped with X-rays from synchrotrons. To analyze the effect of geometry on water flow and fluid distribution we carried out three types of analysis: Firstly, we computed geometrical properties like chord length, distance from the solids, pore size distribution and the Minkowski functionals as a function of pore size. Secondly, the fluid phase distribution as a function of the applied pressure was calculated with a morphological pore network model. Thirdly, the permeability was determined using a state-of-the-art lattice-Boltzmann method. For the simulated structure with the true Minkowski functionals the pores were larger and the computed air-entry value of the artificial medium was reduced to 85% of the value obtained from the scanned sample. The computed permeability for the geometry with the four fitted Minkowski functionals was equal to the permeability of the scanned image. The permeability was much more sensitive to the volume and surface than to curvature and connectivity of the medium. We conclude that the Minkowski functionals are not sufficient to characterize the geometrical properties of a porous structure that are relevant for the distribution of two fluid phases. Depending on the procedure to generate artificial structures with predefined Minkowski functionals, structures differing in pore size distribution can be obtained.

Modeling of the relationship between dipeptide structure and dipeptide stability, permeability, and ACE inhibitory activity.

PubMed

Foltz, Martin; van Buren, Leo; Klaffke, Werner; Duchateau, Guus S M J E

2009-09-01

Selected di- and tripeptides exhibit angiotensin-I converting enzyme (ACE) inhibitory activity in vitro. However, the efficacy in vivo is most likely limited for most peptides due to low bioavailability. The purpose of this study was to identify descriptors of intestinal stability, permeability, and ACE inhibitory activity of dipeptides. A total of 228 dipeptides were synthesized; intestinal stability was obtained by in vitro digestion, intestinal permeability using Caco-2 cells and ACE inhibitory activity by an in vitro assay. Databases were constructed to study the relationship between structure and activity, permeability, and stability. Quantitative structure-activity relationship (QSAR) modeling was performed based on computed models using partial least squares regression based on 400 molecular descriptors. QSAR modeling of dipeptide stability revealed high correlation coefficients (R > 0.65) for models based on Z and X scales. However, amino acid (AA) clustering showed the best results in describing stability of dipeptides. The N-terminal AA residues Asp, Gly, and Pro as well as the C-terminal residues Pro, Ser, Thr, and Asp stabilize dipeptides toward luminal enzymatic peptide hydrolysis. QSAR modeling did not reveal significant correlation models for intestinal permeability. 2D-fingerprint models were identified describing ACE inhibitory activity of dipeptides. The intestinal stability of 12 peptides was predicted. Peptides were synthesized and stability was confirmed in simulated digestion experiments. Based on the results, specific dipeptides can be designed to meet both stability and activity criteria. However, postabsorptive ACE inhibitory activities of dipeptides in vivo are most likely limited due to the very low intestinal permeability of dipeptides.

Structure and physical characteristics of pumice from the climactic eruption of Mount Mazama (Crater Lake), Oregon

USGS Publications Warehouse

Klug, C.; Cashman, K.; Bacon, C.

2002-01-01

The vesicularity, permeability, and structure of pumice clasts provide insight into conditions of vesiculation and fragmentation during Plinian fall and pyroclastic flow-producing phases of the ???7,700 cal. year B.P. climactic eruption of Mount Mazama (Crater Lake), Oregon. We show that bulk properties (vesicularity and permeability) can be correlated with internal textures and that the clast structure can be related to inferred changes in eruption conditions. The vesicularity of all pumice clasts is 75-88%, with >90% interconnected pore volume. However, pumice clasts from the Plinian fall deposits exhibit a wider vesicularity range and higher volume percentage of interconnected vesicles than do clasts from pyroclastic-flow deposits. Pumice permeabilities also differ between the two clast types, with pumice from the fall deposit having higher minimum permeabilities (???5??10-13 m2) and a narrower permeability range (5-50??10-13 m2) than clasts from pyroclastic-flow deposits (0.2-330??10-13 m2). The observed permeability can be modeled to estimate average vesicle aperture radii of 1-5 ??m for the fall deposit clasts and 0.25-1 ??m for clasts from the pyroclastic flows. High vesicle number densities (???109 cm-3) in all clasts suggest that bubble nucleation occured rapidly and at high supersaturations. Post-nucleation modifications to bubble populations include both bubble growth and coalescence. A single stage of bubble nucleation and growth can account for 35-60% of the vesicle population in clasts from the fall deposits, and 65-80% in pumice from pyroclastic flows. Large vesicles form a separate population which defines a power law distribution with fractal dimension D=3.3 (range 3.0-3.5). The large D.value, coupled with textural evidence, suggests that the large vesicles formed primarily by coalescence. When viewed together, the bulk properties (vesicularity, permeability) and textural characteristics of all clasts indicate rapid bubble nucleation followed by bubble growth, coalescence and permeability development. This sequence of events is best explained by nucleation in response to a downward-propagating decompression wave, followed by rapid bubble growth and coalescence prior to magma disruption by fragmentation. The heterogeneity of vesicle sizes and shapes, and the absence of differential expansion across individual clasts, suggest that post-fragmentation expansion played a limited role in the development of pumice structure. The higher vesicle number densities and lower permeabilities of pyroclastic-flow clasts indicate limited coalescence and suggest that fragmentation occurred shortly after decompression. Either increased eruption velocities or increased depth of fragmentation accompanying caldera collapse could explain compression of the pre-fragmentation vesiculation interval.

The permeability of the cGMP-activated channel to organic cations in retinal rods of the tiger salamander.

PubMed Central

Picco, C; Menini, A

1993-01-01

1. The permeability of the channel activated by guanosine 3',5'-cyclic monophosphate (cGMP) to many organic monovalent cations was determined by recording macroscopic currents in excised inside-out patches of plasma membrane from isolated retinal rod outer segments of the tiger salamander. 2. Current-voltage relations were measured when the NaCl of the bathing medium was replaced by salts of organic cations. Permeability ratios relative to Na+ ions were calculated with the Goldman-Hodgkin-Katz potential equation from the measured changes of reversal potentials. 3. Hydroxylammonium+, hydrazinium+ and methylammonium+, which are molecules of very similar shape and size, permeate the channel with very different permeability ratios: 5.92, 1.99 and 0.60 respectively. 4. Methylated and ethylated ammonium+ compounds were investigated. It was found that, not only methylammonium+, but also dimethylammonium+ and ethylammonium+ were permeant with permeability ratios of 0.6, 0.14 and 0.16 respectively. Trimethylammonium+, tetramethylammonium+, diethylammonium+, triethylammonium+, and tetraethylammonium+ were not permeant. 5. Guanidinium+ and its derivatives formamidinium+, aminoguanidinium+, acetamidinium+ and methylguanidinium+ were all permeant with permeability ratios 1.12, 1.00, 0.63, 0.36 and 0.33 respectively. 6. The cGMP-activated channel was found to be permeable to at least thirteen organic cations. Molecular models of the permeant cations indicate that the cross-section of the narrowest part of the pore must be at least as large as a rectangle of 0.38 x 0.5 nm dimensions. PMID:7683718

In situ investigation of the effect of TiF4 and CO2 laser irradiation on the permeability of eroded enamel.

PubMed

Lepri, Taísa Penazzo; Colucci, Vivian; Turssi, Cecília Pedroso; Corona, Silmara Aparecida Milori

2015-06-01

Interest in erosion and its role in tooth wear has increased considerably. Due to the limited contribution of patients in modifying their dietary habits, therapeutic resources aiming to reduce the progression of erosion-like lesions have been discussed. This study sought to evaluate the effect of TiF4 and CO2 laser in controlling the permeability of in situ eroded enamel. Ten volunteers wore an intraoral palatal device containing two enamel slabs, treated with TiF4 gel and TiF4 gel + CO2 or placebo gel and placebo gel + CO2. After the washout period, volunteers were crossed over to the other treatment. During both phases, specimens were submitted to erosive challenges and then evaluated for permeability measured as the percentage of copper ion penetration over the total enamel thickness. Two-way analysis of variance (ANOVA) revealed that there was a significant interaction between the factors under study (p = 0.0002). Tukey's test showed that TiF4 significantly reduced the enamel permeability of eroded enamel specimens, regardless of whether CO2 laser irradiation was performed. It may be concluded that when the placebo gel was applied, CO2 laser was able to reduce enamel permeability; however, when TiF4 was applied, laser irradiation did not imply a reduction in permeability. TiF4 provided a lower permeability of eroded enamel, regardless of whether the CO2 laser was used. Copyright © 2015 Elsevier Ltd. All rights reserved.

Mechanisms of Visceral Organ Crosstalk: Importance of Alterations in Permeability in Rodent Models

PubMed Central

Greenwood-Van Meerveld, B; Mohammadi, E; Tyler, K; Van Gordon, S; Parker, A; Towner, R; Hurst, R

2015-01-01

Purpose The pathophysiology of painful bladder syndrome (PBS) is poorly understood; however, there is evidence of female predominance and comorbidity with irritable bowel syndrome (IBS). Our hypothesis is that cross-sensitization between the bladder and colon is due to altered permeability in one organ affecting the other organ. Materials and methods Experiments were performed in anesthetized, ovariectomized (OVX) female rats. In separate groups, protamine sulfate was infused into the bladder or TNBS was infused into the colon, with untreated rats serving as controls. Both bladder and colonic tissue were harvested for all rats at 1, 3, and 5 days post-treatment. Permeability was assessed in vitro in Ussing chambers via measurements of transepithelial electrical resistance (TEER) and macromolecular flux of Fluorescein isothiocyanate (FITC)-4 dextran. Results Exposing the bladder to protamine sulfate induced a significant (p<0.05) decrease in bladder TEER and an increase in the translocation of FITC across the tissue compared to controls at 1 and 3 days. Colonic tissue from rats with enhanced bladder permeability exhibited a significant (p<0.05) decrease in TEER and increase in FITC when compared to untreated controls at all time points. Conversely, when colonic permeability was increased with TNBS, we observed an increase in bladder permeability in the absence of any changes to the bladder urothelium. Conclusions Changes in epithelial permeability may represent a novel mechanism for visceral organ crosstalk and may explain the overlapping symptomology of PBS and IBS. PMID:25776913

Simulating the Heterogeneity in Braided Channel Belt Deposits: 2. Examples of Results and Comparison to Natural Deposits

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

Guin, Arijit; Ramanathan, Ramya; Ritzi, Robert W.

In Part 1 of this series we presented a methodology and a code for modeling the hierarchical sedimentary architecture in braided channel belt deposits. Here, in Part 2, the code was used to create a digital model of this architecture, and the corresponding spatial distribution of permeability. The simulated architecture was compared to the real stratal architecture observed in an abandoned channel belt of the Sagavanirktok River, Alaska by Lunt et al. (2004). The comparisons included assessments of similarity which were both qualitative and quantitative. From the qualitative comparisons we conclude that a synthetic deposit created by the code hasmore » unit types, at each level, with a geometry which is generally consistent with the geometry of unit types observed in the field. The digital unit types would generally be recognized as representing their counterparts in nature, including cross stratasets, lobate and scroll bar deposits, channel fills, etc. Furthermore, the synthetic deposit has a hierarchical spatial relationship among these units which represents how the unit types are observed in field exposures and in geophysical images. In quantitative comparisons the proportions and the length, width, and height of unit types at different scales, across all levels of the stratal hierarchy compare well between the digital and the natural deposits. A number of important attributes of the channel belt model were shown to be influenced by more than one level within the hierarchy of stratal architecture. First, the high-permeability open-framework gravels percolated at all levels and thus formed preferential flow pathways. Open framework gravels are indeed known to form preferential flow pathways in natural channel belt deposits. The nature of a percolating cluster changed across different levels of the hierarchy of stratal architecture. As a result of this geologic structure, the percolation occurs at proportions of open-framework gravels below the theoretical percolation threshold for random infinite media. Second, when the channel belt model was populated with permeability distributions by lowest-level unit type, the composite permeability semivariogram contained structures that were identifiable at more than one scale, and each of these structures could be directly linked to unit types of different scales existing at different levels within the hierarchy of strata. These collective results are encouraging with respect to our goal that this model be relevant as a base case in future studies for testing ideas in research addressing the upscaling problem in aquifers and reservoirs with multi-scale heterogeneity.« less

The permeaiblity of fault-zones:the role of stylolites as incipit of dissolution

NASA Astrophysics Data System (ADS)

Magni, Silvana

2017-04-01

Fault zones and fractures play an important role in fluid circulation and then in dissolution, acting as barriers or conductors depending on the distribution of other features associated with them and on the specific conditions (lithological and structural, as well). The fault zone have a high permeability only in the early stages of the movement but shortly after recrystallization and reprecipitation processes greatly reduce the permeability within them. Indeed the dissolution is a complex phenomenon which involves both several factors that lead to the formation of caves and karst systems often complex. Traditionally, in the field of karst , the dissolution is associated with extensional structures such as faults and joints believing that they are more favorable to the water circulation. In this context compressional tectonic structures, as like the stylolites, are never considered. In fact the stylolites play an important role in the fluid circulation (Rawling, 2001) and in particular in the incipit of dissolution and then of the karst. We have so focused our research on the study of permeability of four fault zones in a karst area of Alte Murge (South Italy). Through a detailed structural analysis in the field and using the method of Caine (Caine, 1996), we reconstructed the permeability of the four previous fault zones. Our attention was focused on faults, joints and on stylolites. Contrary to the literature the dissolution and therefore the karst was mainly found along the stylolites and only secondarily along faults. No sign of dissolution was found along the joints. In the context of karst studies, the stylolites, which are structures due to pressure solution has never been taken into account, thinking that in compressional structures is not possible any circulation of water and that therefore there is no fluid-rock interaction. No consideration has been given to the enormous role that the pressure and the microfluidic that are created have in this context. The styololites, the focus of our research open important questions about their exact role as incipit of the dissolution. Through petrophysical analysis and microstructural we are characterizing the porosity and permeability near the stylolites. Recently, fluid-rock interactions and their impact on carbonate rocks is becoming very important because of an increasing interest it the carbonate reservoirs as a consequence of a progressive deterioration of the quantity and quality of the groundwater due to increasing pollution phenomena. In fact the aquifers represent about 40% of the drinking water resources and their importance will increase in coming years. REFERENCESE Caine, J.S.,Evans, J.P., Forster,C.B. (1996). Fault zone architecture and permeability structure. Geology 24, 1025-1032 Rawling,G.C., Goodwin,L.B., Wilson,J.L. (2001). Internal architecture permeability structure and hydrogeologic significance of contrasting fault-zone types. Geology 29, 43-46

A computer program for simulating geohydrologic systems in three dimensions

USGS Publications Warehouse

Posson, D.R.; Hearne, G.A.; Tracy, J.V.; Frenzel, P.F.

1980-01-01

This document is directed toward individuals who wish to use a computer program to simulate ground-water flow in three dimensions. The strongly implicit procedure (SIP) numerical method is used to solve the set of simultaneous equations. New data processing techniques and program input and output options are emphasized. The quifer system to be modeled may be heterogeneous and anisotropic, and may include both artesian and water-table conditions. Systems which consist of well defined alternating layers of highly permeable and poorly permeable material may be represented by a sequence of equations for two dimensional flow in each of the highly permeable units. Boundaries where head or flux is user-specified may be irregularly shaped. The program also allows the user to represent streams as limited-source boundaries when the streamflow is small in relation to the hydraulic stress on the system. The data-processing techniques relating to ' cube ' input and output, to swapping of layers, to restarting of simulation, to free-format NAMELIST input, to the details of each sub-routine 's logic, and to the overlay program structure are discussed. The program is capable of processing large models that might overflow computer memories with conventional programs. Detailed instructions for selecting program options, for initializing the data arrays, for defining ' cube ' output lists and maps, and for plotting hydrographs of calculated and observed heads and/or drawdowns are provided. Output may be restricted to those nodes of particular interest, thereby reducing the volumes of printout for modelers, which may be critical when working at remote terminals. ' Cube ' input commands allow the modeler to set aquifer parameters and initialize the model with very few input records. Appendixes provide instructions to compile the program, definitions and cross-references for program variables, summary of the FLECS structured FORTRAN programming language, listings of the FLECS and FORTRAN source code, and samples of input and output for example simulations. (USGS)

Gas Permeable Chemochromic Compositions for Hydrogen Sensing

NASA Technical Reports Server (NTRS)

Mohajeri, Nahid (Inventor); Muradov, Nazim (Inventor); Tabatabaie-Raissi, Ali (Inventor); Bokerman, Gary (Inventor)

2013-01-01

A (H2) sensor composition includes a gas permeable matrix material intermixed and encapsulating at least one chemochromic pigment. The chemochromic pigment produces a detectable change in color of the overall sensor composition in the presence of H2 gas. The matrix material provides high H2 permeability, which permits fast permeation of H2 gas. In one embodiment, the chemochromic pigment comprises PdO/TiO2. The sensor can be embodied as a two layer structure with the gas permeable matrix material intermixed with the chemochromic pigment in one layer and a second layer which provides a support or overcoat layer.

Pressure sensitivity of low permeability sandstones

USGS Publications Warehouse

Kilmer, N.H.; Morrow, N.R.; Pitman, Janet K.

1987-01-01

Detailed core analysis has been carried out on 32 tight sandstones with permeabilities ranging over four orders of magnitude (0.0002 to 4.8 mD at 5000 psi confining pressure). Relationships between gas permeability and net confining pressure were measured for cycles of loading and unloading. For some samples, permeabilities were measured both along and across bedding planes. Large variations in stress sensitivity of permeability were observed from one sample to another. The ratio of permeability at a nominal confining pressure of 500 psi to that at 5000 psi was used to define a stress sensitivity ratio. For a given sample, confining pressure vs permeability followed a linear log-log relationship, the slope of which provided an index of pressure sensitivity. This index, as obtained for first unloading data, was used in testing relationships between stress sensitivity and other measured rock properties. Pressure sensitivity tended to increase with increase in carbonate content and depth, and with decrease in porosity, permeability and sodium feldspar. However, scatter in these relationships increased as permeability decreased. Tests for correlations between pressure sensitivity and various linear combinations of variables are reported. Details of pore structure related to diagenetic changes appears to be of much greater significance to pressure sensitivity than mineral composition. ?? 1987.

Corneal and conjunctival drug permeability: Systematic comparison and pharmacokinetic impact in the eye.

PubMed

Ramsay, Eva; Del Amo, Eva M; Toropainen, Elisa; Tengvall-Unadike, Unni; Ranta, Veli-Pekka; Urtti, Arto; Ruponen, Marika

2018-07-01

On the surface of the eye, both the cornea and conjunctiva are restricting ocular absorption of topically applied drugs, but barrier contributions of these two membranes have not been systemically compared. Herein, we studied permeability of 32 small molecular drug compounds across an isolated porcine cornea and built a quantitative structure-property relationship (QSPR) model for the permeability. Corneal drug permeability (data obtained for 25 drug molecules) showed a 52-fold range in permeability (0.09-4.70 × 10 -6  cm/s) and the most important molecular descriptors in predicting the permeability were hydrogen bond donor, polar surface area and halogen ratio. Corneal permeability values were compared to their conjunctival drug permeability values. Ocular drug bioavailability and systemic absorption via conjunctiva were predicted for this drug set with pharmacokinetic calculations. Drug bioavailability in the aqueous humour was simulated to be <5% and trans-conjunctival systemic absorption was 34-79% of the dose. Loss of drug across the conjunctiva to the blood circulation restricts significantly ocular drug bioavailability and, therefore, ocular absorption does not increase proportionally with the increasing corneal drug permeability. Copyright © 2018 Elsevier B.V. All rights reserved.

A new structure of permeable pavement for mitigating urban heat island.

PubMed

Liu, Yong; Li, Tian; Peng, Hangyu

2018-09-01

The urban heat island (UHI) effect has been a great threat to human habitation, and how to mitigate this problem has been a global concern over decades. This paper addresses the cooling effect of a novel permeable pavement called evaporation-enhancing permeable pavement, which has capillary columns in aggregate and a liner at the bottom. To explore the efficiency of mitigating the UHI, bench-scale permeable pavement units with capillary columns were developed and compared with conventional permeable pavement. Criteria of capillary capacities of the column, evaporation rates, and surface temperature of the pavements were monitored under simulated rainfall and Shanghai local weather conditions. Results show the capillary column was important in increasing evaporation by lifting water from the bottom to the surface, and the evaporation-enhancing permeable pavement was cooler than a conventional permeable pavement by as much as 9.4°C during the experimental period. Moreover, the cooling effect of the former pavement could persist more than seven days under the condition of no further rainfall. Statistical analysis result reveals that evaporation-enhancing permeable pavement can mitigate the UHI effect significantly more than a conventional permeable pavement. Copyright © 2018 Elsevier B.V. All rights reserved.

Scale dependence of in-situ permeability measurements in the Nankai accretionary prism: The role of fractures

NASA Astrophysics Data System (ADS)

Boutt, David F.; Saffer, Demian; Doan, Mai-Linh; Lin, Weiren; Ito, Takatoshi; Kano, Yasuyuki; Flemings, Peter; McNeill, Lisa C.; Byrne, Timothy; Hayman, Nicholas W.; Moe, Kyaw Thu

2012-04-01

Modeling studies suggest that fluid permeability is an important control on the maintenance and distribution of pore fluid pressures at subduction zones generated through tectonic loading. Yet, to date, few data are available to constrain permeability of these materials, at appropriate scales. During IODP Expedition 319, downhole measurements of permeability within the uppermost accretionary wedge offshore SW Japan were made using a dual-packer device to isolate 1 m sections of borehole at a depth of 1500 m below sea floor. Analyses of pressure transients using numerical models suggest a range of in-situ fluid permeabilities (5E-15-9E-17 m2). These values are significantly higher than those measured on core samples (2E-19 m2). Borehole imagery and cores suggests the presence of multiple open fractures at this depth of measurement. These observations suggest that open permeable natural fractures at modest fracture densities could be important contributors to overall prism permeability structure at these scales.

Electrohydraulic shock wave generation as a means to increase intrinsic permeability of mortar

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

Maurel, O.; Reess, T.; Matallah, M.

2010-12-15

This article discusses the influence of compressive shock waves on the permeability of cementitious materials. Shock waves are generated in water by Pulsed Arc Electrohydraulic Discharges (PAED). The practical aim is to increase the intrinsic permeability of the specimens. The maximum pressure amplitude of the shock wave is 250 MPa. It generates damage in the specimens and the evolution of damage is correlated with the intrinsic permeability of the mortar. A threshold of pressure is observed. From this threshold, the increase of permeability is linear in a semi-log plot. The influence of repeated shocks on permeability is also discussed. Qualitativemore » X Ray Tomography illustrates the evolution of the microstructure of the material leading to the increase of permeability. Comparative results from mercury intrusion porosimetry (MIP) show that the micro-structural damage process starts at the sub-micrometric level and that the characteristic size of pores of growing volume increases.« less

Urban permeable pavement system design based on “sponge city” concept

NASA Astrophysics Data System (ADS)

Yu, M. M.; Zhu, J. W.; Gao, W. F.; Xu, D. P.; Zhao, M.

2017-08-01

Based on the “sponge city” concept, to implement the goal of building a city within the city to solve the sponge waterlogging, rational utilization of water resources, reduce water pollution this paper, combined with the city planning level in China, establishes the design system of city road flooding from the macro, medium and micro level, explore the design method of city water permeable pavement system, and has a practical significance the lower flood risk water ecological problems. On the macro level, we established an urban pavement sponge system under the regional ecological pattern by “spot permeable open space - low impact developing rain water road system - catchment area and catchment wetland”. On a medium level, this paper proposed the permeable suitability of pavement and the planning control indicators when combined with urban functional districts to conduct permeable pavement roads plans and controls. On micro level, the paper studied sponge technology design of permeable pavement from road structure, surface material, and other aspects aimed at the pavement permeability requirements.

Permeability of continental crust influenced by internal and external forcing

USGS Publications Warehouse

Rojstaczer, S.A.; Ingebritsen, S.E.; Hayba, D.O.

2008-01-01

The permeability of continental crust is so highly variable that it is often considered to defy systematic characterization. However, despite this variability, some order has been gleaned from globally compiled data. What accounts for the apparent coherence of mean permeability in the continental crust (and permeability-depth relations) on a very large scale? Here we argue that large-scale crustal permeability adjusts to accommodate rates of internal and external forcing. In the deeper crust, internal forcing - fluxes induced by metamorphism, magmatism, and mantle degassing - is dominant, whereas in the shallow crust, external forcing - the vigor of the hydrologic cycle - is a primary control. Crustal petrologists have long recognized the likelihood of a causal relation between fluid flux and permeability in the deep, ductile crust, where fluid pressures are typically near-lithostatic. It is less obvious that such a relation should pertain in the relatively cool, brittle upper crust, where near-hydrostatic fluid pressures are the norm. We use first-order calculations and numerical modeling to explore the hypothesis that upper-crustal permeability is influenced by the magnitude of external fluid sources, much as lower-crustal permeability is influenced by the magnitude of internal fluid sources. We compare model-generated permeability structures with various observations of crustal permeability. ?? 2008 The Authors Journal compilation ?? 2008 Blackwell Publishing Ltd.

Experimental techniques and computational methods toward the estimation of the effective two-phase flow coefficients and multi-scale heterogeneities of soils

NASA Astrophysics Data System (ADS)

Tsakiroglou, C. D.; Aggelopoulos, C. A.; Sygouni, V.

2009-04-01

A hierarchical, network-type, dynamic simulator of the immiscible displacement of water by oil in heterogeneous porous media is developed to simulate the rate-controlled displacement of two fluids at the soil column scale. A cubic network is constructed, where each node is assigned a permeability which is chosen randomly from a distribution function. The intensity of heterogeneities is quantified by the width of the permeability distribution function. The capillary pressure at each node is calculated by combining a generalized Leverett J-function with a Corey type model. Information about the heterogeneity of soils at the pore network scale is obtained by combining mercury intrusion porosimetry (MIP) data with back-scattered scanning electron microscope (BSEM) images [1]. In order to estimate the two-phase flow properties of nodes (relative permeability and capillary pressure functions, permeability distribution function) immiscible and miscible displacement experiments are performed on undisturbed soil columns. The transient responses of measured variables (pressure drop, fluid saturation averaged over five successive segments, solute concentration averaged over three cross-sections) are fitted with models accounting for the preferential flow paths at the micro- (multi-region model) and macro-scale (multi flowpath model) because of multi-scale heterogeneities [2,3]. Simulating the immiscible displacement of water by oil (drainage) in a large netork, at each time step, the fluid saturation and pressure of each node are calculated formulating mass balances at each node, accounting for capillary, viscous and gravity forces, and solving the system of coupled equations. At each iteration of the algorithm, the pressure drop is so selected that the total flow rate of the injected fluid is kept constant. The dynamic large-scale network simulator is used (1) to examine the sensitivity of the transient responses of the axial distribution of fluid saturation and total pressure drop across the network to the permeability distribution function, spatial correlations of permeability, and capillary number, and (2) to estimate the effective (up-scaled) relative permeability functions at the soil column scale. In an attempt to clarify potential effects of the permeability distribution and spatial permeability correlations on the transient responses of the pressure drop across a soil column, signal analysis with wavelets is performed [4] on experimental and simulated results. The transient variation of signal energy and frequency of pressure drop fluctuations at the wavelet domain are correlated with macroscopic properties such as the effective water and oil relative permeabilities of the porous medium, and microscopic properties such as the variation of the permeability distribution of oil-occupied nodes. Toward the solution of the inverse problem, a general procedure is suggested to identify macro-heterogeneities from the fast analysis of pressure drop signals. References 1. Tsakiroglou, C.D. and M.A. Ioannidis, "Dual porosity modeling of the pore structure and transport properties of a contaminated soil", Eur. J. Soil Sci., 59, 744-761 (2008). 2. Aggelopoulos, C.A., and C.D. Tsakiroglou, "Quantifying the Soil Heterogeneity from Solute Dispersion Experiments", Geoderma, 146, 412-424 (2008). 3. Aggelopoulos, C.A., and C.D. Tsakiroglou, "A multi-flow path approach to model immiscible displacement in undisturbed heterogeneous soil columns", J. Contam. Hydrol., in press (2009). 4. Sygouni, V., C.D. Tsakiroglou, and A.C. Payatakes, "Using wavelets to characterize the wettability of porous materials", Phys. Rev. E, 76, 056304 (2007).

Facies Distribution and Petrophysical Properties of Shoreface-Offshore Transition Environment in Sandakan Formation, NE Sabah Basin

NASA Astrophysics Data System (ADS)

Majid, M. Firdaus A.; Suhaili Ismail, M.; Rahman, A. Hadi A.; Azfar Mohamed, M.

2017-10-01

Newly exposed outcrop of Miocene shallow marine sandstone in Sandakan Formation, allows characterization of the facies distribution and petrophysical properties of shoreface to offshore transition environment. Six facies are defined: (1) Poorly bioturbated Hummocky Cross Stratified (HCS) sandstone (F1), (2) Moderately bioturbated HCS sandstone (F2), (3) Well bioturbated HCS sandstone (F3), (4) Poorly bioturbated Swaley Cross Stratified (SCS) sandstone (F4), (5) Interbedded HCS sandstone with sand-silt mudstone, (6) Heterolithic mudstone. The sedimentary successions were deposited in upper to lower shoreface, and offshore transition environment. Facies F3, F4 and F5 shows good reservoir quality with good porosity and fair permeability values from 20% to 21% and 14 mD to 33 mD respectively. While Facies F1 exhibits poor reservoir quality with low permeability values 3.13 mD.

Microalgae fractionation using steam explosion, dynamic and tangential cross-flow membrane filtration.

PubMed

Lorente, E; Hapońska, M; Clavero, E; Torras, C; Salvadó, J

2017-08-01

In this study, the microalga Nannochloropsis gaditana was subjected to acid catalysed steam explosion treatment and the resulting exploded material was subsequently fractionated to separate the different fractions (lipids, sugars and solids). Conventional and vibrational membrane setups were used with several polymeric commercial membranes. Two different routes were followed: 1) filtration+lipid solvent extraction and 2) lipid solvent extraction+filtration. Route 1 revealed to be much better since the used membrane for filtration was able to permeate the sugar aqueous phase and retained the fraction containing lipids; after this, an extraction required a much lower amount of solvent and a better recovering yield. Filtration allowed complete lipid rejection. Dynamic filtration improved permeability compared to the tangential cross-flow filtration. Best membrane performance was achieved using a 5000Da membrane with the dynamic system, obtaining a permeability of 6L/h/m 2 /bar. Copyright © 2017 Elsevier Ltd. All rights reserved.

Long-term stormwater quantity and quality performance of permeable pavement systems.

PubMed

Brattebo, Benjamin O; Booth, Derek B

2003-11-01

This study examined the long-term effectiveness of permeable pavement as an alternative to traditional impervious asphalt pavement in a parking area. Four commercially available permeable pavement systems were evaluated after 6 years of daily parking usage for structural durability, ability to infiltrate precipitation, and impacts on infiltrate water quality. All four permeable pavement systems showed no major signs of wear. Virtually all rainwater infiltrated through the permeable pavements, with almost no surface runoff. The infiltrated water had significantly lower levels of copper and zinc than the direct surface runoff from the asphalt area. Motor oil was detected in 89% of samples from the asphalt runoff but not in any water sample infiltrated through the permeable pavement. Neither lead nor diesel fuel were detected in any sample. Infiltrate measured 5 years earlier displayed significantly higher concentrations of zinc and significantly lower concentrations of copper and lead.

Possibilities of fish passage through the block ramp: Model-based estimation of permeability.

PubMed

Plesiński, Karol; Bylak, Aneta; Radecki-Pawlik, Artur; Mikołajczyk, Tomasz; Kukuła, Krzysztof

2018-08-01

Block ramps offer an opportunity to combine hydrotechnical structures with fish passages. The primary study objective was to evaluate the effectiveness of a block ramp for upstream fish movement in a mountain stream. Geodetic measurements of the bottom surface and water level were taken for three cross-sections. The description of the geometric and hydrodynamic parameters of the block ramp was supplemented with information on the width and length of crevices between boulders. Measurements of the geometric and hydrodynamic parameters of the block ramp were performed at 76 measurement sites, at three different types of discharge. Ichthyological data were collected in the analyzed stream. Measurements covered among others total length, width, and height of caught fish. Salmonid, cottid, balitorid, and cyprinid fish were studied. The determination of the main effects of the geometric and hydrodynamic parameters of the block ramp on the possibilities of use by target fish species employed generalized linear models (GLMs). The study shows that the block ramp cannot provide longitudinal connectivity and migration of fish occurring in the mountain stream. According to estimates, the block ramp did not meet the permeability expectations. The reason for low usefulness of the ramp for fish is particularly excessively strong water current. The stream concentration constituted an unsurmountable velocity barrier for fish moving upstream for each of the analyzed discharges. The developed model suggests that some crevices in the side zones of the ramp could be parts of the migration corridor, but only for small and medium-sized fish. At medium and high water stages, movement of fish in crevices was difficult due to fast water current, and at low and very low discharges, some crevices lost their permeability, and could become ecological traps for fish. The necessity of estimation of ramp permeability during pre-construction phase was emphasized. Copyright © 2018 Elsevier B.V. All rights reserved.

Relations between the structure of storage and the transport of chemical compounds in karstic aquifers

NASA Astrophysics Data System (ADS)

Vaute, L.; Drogue, C.; Garrelly, L.; Ghelfenstein, M.

1997-12-01

Study of the movement of chemical compounds naturally present in the water, or which result from pollution, are examined according to the reservoir structure in karstic aquifers. Structure is represented by a simple geometrical model; slow flow takes place in blocks with a network of low-permeability cracks. The blocks are separated by highly permeable karstic conduits that allow rapid flow, and these form the aquifer drainage system. The karst studied covers 110 km 2. It is fed by an interrupted stream draining a 35 km 2 non-karstic basin, contaminated at the entry to the karst by effluents from a sewage treatment station. The underground water reappears as a resurgence with an annual average flow of approximately 1 m 3 s -1, after an apparent underground course of 8 km in the karst. Several local sources of pollution (effluent from septic tanks) contaminate the underground water during its course. Sixteen measurement operations were performed at 12 water points, between the interrupted stream and the spring. Some sampling points were at drains, and others were in the low-permeability fissured blocks. Comparison at each point of the concentrations of 14 chemical compounds gave the following results: when pollutant discharge occurs in a permeable zone, movement is rapid in the drainage network formed by the karstic conduits, and does not reach the less permeable fissured blocks which are thus protected; however, if discharge is in a low-permeability zone, the flow does not allow rapid movement of the polluted water, and this increases the pollutant concentration at the discharge. This simple pattern can be upset by a reversal of the apparent piezometric gradient between a block and a conduit during floods or pumping; this may reverse flow directions and hence modify the movement of contaminants. The study made it possible to site five boreholes whose positions in the karstic structure were unknown, showing the interest of such an approach for the forecasting of the impact of potential pollution.

CRLH-TL Sensors for Flow Inhomogeneties Detection of Pneumatic Conveyed Pulverized Solids

NASA Astrophysics Data System (ADS)

Angelovski, Aleksandar; Penirschke, Andreas; Jakoby, Rolf

2011-08-01

This paper presents an application of a Composite Right/Left-Handed (CRLH) Transmission Line resonator for a compact mass flow detector which is able to detect inhomogeneous flows. In this concept, series capacitors and shunt inductors are used to synthesize a medium with simultaneously negative permeability and permittivity - the so called metamaterial. The helix shape of the cylindrical CRLH-TL sensor offers the possibility to detect flow inhomogeneities within the pipeline which can be used to correct the detected massflow rate. A combination of two CRLH-TL structures within the same cross-section of the pipeline can improve the angular sensitivity of the sensor. A prototype was realized and tested in a dedicated measurement setup to prove the concept.

Anatomy of the grainstone shoal facies of the Salem Limestone (Mississippian) of southern Indiana

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

Dodd, J.R.; Petzold, D.D.; Thompson, T.A.

In 1990 M.A. Brown described the middle Mississippian (Valmeyeran) Salem Limestone exposed on the eastern side of the Illinois Basin as consisting of a massive grainstone shoal facies behind which developed a sand flat, an open lagoon, and a restricted lagoon facies. Smaller intrashoal channels provided limited exchange between lagoon and open ocean. The authors have made detailed studies of sedimentary structures and petrography of the shoal facies in three settings: the shoal proper, an intrashoal channel, and an intershoal channel. The shoal and channel facies consists of tabular-planar and trough cross-stratified beds of grainstone containing echinoderm and fenestrate bryozoanmore » grains as their primary constituents. Prominent hardgrounds that have up to 1 m of erosional relief occur in two of the sections. Despite the apparent uniformity of composition of the shoal, porosity and especially permeability varies over a wide range, suggesting a range of cementation patterns within the shoal. Most of the cement in the shoal consists of syntaxial overgrowths on echinoderm grains. Cementation is less and thus porosity and permeability greater, in portions of the shoals containing a lower concentration of echinoderm grains and grains with thick micrite envelopes. However, some portions of the intershoal channel facies that contain a high percentage of ooids have reduced porosity and permeability due to crushing of ooids, producing micrite that clogged the pores. Primary sedimentary features of the shoal facies were produced predominantly by storm reworking of carbonate grains produced in situ and perhaps in part washed in from surrounding environments.« less

Magnetic permeability as a predictor of the artefact size caused by orthodontic appliances at 1.5 T magnetic resonance imaging.

PubMed

Blankenstein, Felix H; Asbach, Patrick; Beuer, Florian; Glienke, Johannes; Mayer, Stefan; Zachriat, Christine

2017-01-01

Artefacts caused by orthodontic attachments limit the diagnostic value and lead to removal of these appliances before magnetic resonance imaging. Magnetic permeability can predict the artefact size. There is no standardised approach to determine the permeability of such attachments. The aim was to establish a reliable approach to determine artefact size caused by orthodontic attachments at 1.5 T MRI. Artefact radii of 21 attachments were determined applying two prevalent sequences of the head and neck region (turbo spin echo and gradient echo). The instrument Ferromaster (Stefan Mayer Instruments, Dinslaken) is approved for permeability measurements of objects with a minimum size (d = 20 mm, h = 5 mm). Eleven small test specimens of known permeability between 1.003 and 1.431 were produced. They are slightly larger than the orthodontic attachments. Their artefacts were measured and cross tabulated against the permeability. The resulting curve was used to compare the orthodontic attachments with the test bodies. Steel caused a wide range of artefact size of 10-74 mm subject to their permeability. Titanium, cobalt-chromium and ceramic materials produced artefact radii up to 20 mm. Measurement of artefacts of the test bodies revealed an interrelationship according to a root function. The artefact size of all brackets was below that root function. The permeability can be reliably assessed by conventional measurement devices and the artefact size can be predicted. The radiologist is able to decide whether or not the orthodontic attachments should be removed. This study clarifies whether an orthodontic appliance must be removed before taking an MRI.

Modeling relative permeability of water in soil: Application of effective-medium approximation and percolation theory

NASA Astrophysics Data System (ADS)

Ghanbarian, Behzad; Sahimi, Muhammad; Daigle, Hugh

2016-07-01

Accurate prediction of the relative permeability to water under partially saturated condition has broad applications and has been studied intensively since the 1940s by petroleum, chemical, and civil engineers, as well as hydrologists and soil scientists. Many models have been developed for this purpose, ranging from those that represent the pore space as a bundle of capillary tubes, to those that utilize complex networks of interconnected pore bodies and pore throats with various cross-section shapes. In this paper, we propose an approach based on the effective-medium approximation (EMA) and percolation theory in order to predict the water relative permeability. The approach is general and applicable to any type of porous media. We use the method to compute the water relative permeability in porous media whose pore-size distribution follows a power law. The EMA is invoked to predict the relative permeability from the fully saturated pore space to some intermediate water saturation that represents a crossover from the EMA to what we refer to as the "critical region." In the critical region below the crossover water saturation Swx, but still above the critical water saturation Swc (the residual saturation or the percolation threshold of the water phase), the universal power law predicted by percolation theory is used to compute the relative permeability. To evaluate the accuracy of the approach, data for 21 sets of undisturbed laboratory samples were selected from the UNSODA database. For 14 cases, the predicted relative permeabilities are in good agreement with the data. For the remaining seven samples, however, the theory underestimates the relative permeabilities. Some plausible sources of the discrepancy are discussed.

Structural and physicochemical characterization of thermoplastic corn starch films containing microalgae.

PubMed

Fabra, María José; Martínez-Sanz, Marta; Gómez-Mascaraque, L G; Gavara, Rafael; López-Rubio, Amparo

2018-04-15

This work provides an in-depth analysis on how the addition of different microalgae species (Nannochloropsis, Spirulina and Scenedesmus) affected the structural and physicochemical properties of thermoplastic corn starch biocomposites. Structural characterization was conducted by combined SAXS/WAXS experiments and it was correlated with mechanical and barrier properties of the biocomposites. A water vapour permeability drop of ca. 54% was observed upon addition of the different microalgae species. The oxygen permeability and the mechanical properties of biocomposites containing Spirulina or Scenedesmus were not improved since the presence of microalgae hindered the re-arrangement and packing of the lamellar structure of starch polymeric chains, according to the SAXS results. Nannochloropsis caused a great reduction of the matrix rigidity and, the oxygen permeability was also improved. Therefore, all of these features make the Nannochloropsis biocomposites an alternative to generate biodegradable food packaging materials with the additional advantage that they can be easily scaled-up. Copyright © 2018 Elsevier Ltd. All rights reserved.

Surface resistivity as an alternative for rapid chloride permeability test of hardened concrete.

DOT National Transportation Integrated Search

2015-03-01

Kansas experiences harsh winters that require frequent use of de-icing salts, making it critical to the long-term : durability of concrete structures that the permeability is kept under control. Under current KDOT specification, the : Rapid Chloride ...

Characterization of Carbonate Hydrostratigraphy Using Ambient Seismic Noise: A Pilot Study in the Floridan Aquifer System, Ocala, FL, USA

NASA Astrophysics Data System (ADS)

James, S.; Screaton, E.; Russo, R. M.; Panning, M. P.; Bremner, P. M.; Stanciu, A. C.; Torpey, M. E.; Hongsresawat, S.; Farrell, M. E.

2014-12-01

Defining zones of high and low hydraulic conductivity within aquifers is vital to hydrogeologic research and groundwater management. Carbonate aquifers are particularly difficult to characterize due to dissolution and dolomitization. We investigated a new imaging technique for aquifer characterization that uses cross-correlation of ambient seismic noise to determine seismic velocity structure. Differences in densities between confining units and high permeability flow zones can produce distinct seismic velocities in the correlated signals. We deployed an array of 9 short period geophones from 11/2013 to 3/2014 in Indian Lake State Forest, Florida, to determine if the high frequency diffusive seismic wavefield can be used for imaging hydrostratigraphy. Here, a thin surficial layer of siliciclastic deposits overlie a ~ 0.6 km sequence of Cenozoic limestone and dolomite units that comprise the Floridan Aquifer System (FAS). A low permeability dolomite unit vertically divides the FAS throughout most of Florida. Deep boreholes surrounding the site constrain hydrostratigraphy, however the horizontal continuity of the middle dolomite unit as well as its effectiveness as a confining unit in the study area are not well known. The stations were spaced at distances ranging from 0.18 to 2.6 km, and yielded 72 cross-correlation Green's functions for Rayleigh wave propagation at frequencies between 0.2 and 40 Hz, with dominant peaks around 0.8 Hz, 3 Hz and 13 Hz. Local vehicle traffic did interfere to a degree with the correlation of the diffuse waves, but was minimized by using only nighttime data. At the lowest frequencies (greatest depths) investigated, velocities increase with depth; however, correlations become less coherent at higher frequencies, perhaps due to shallow complex scattering. Comparison of cross-correlations for all station pairs also indicates spatial variations in velocity. Thus, the method shows promise for characterization of the heterogeneity of the Floridan Aquifer System.

Effect of UV-ozone treatment on poly(dimethylsiloxane) membranes: surface characterization and gas separation performance.

PubMed

Fu, Ywu-Jang; Qui, Hsuan-zhi; Liao, Kuo-Sung; Lue, Shingjiang Jessie; Hu, Chien-Chieh; Lee, Kueir-Rarn; Lai, Juin-Yih

2010-03-16

A thin SiO(x) selective surface layer was formed on a series of cross-linked poly(dimethylsiloxane) (PDMS) membranes by exposure to ultraviolet light at room temperature in the presence of ozone. The conversion of the cross-linked polysiloxane to SiO(x) was monitored by attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy, X-ray photoelectron spectroscopy (XPS), energy-dispersive X-ray (EDX) microanalysis, contact angle analysis, and atomic force microscopy (AFM). The conversion of the cross-linked polysiloxane to SiO(x) increased with UV-ozone exposure time and cross-linking agent content, and the surface possesses highest conversion. The formation of a SiO(x) layer increased surface roughness, but it decreased water contact angle. Gas permeation measurements on the UV-ozone exposure PDMS membranes documented interesting gas separation properties: the O(2) permeability of the cross-linked PDMS membrane before UV-ozone exposure was 777 barrer, and the O(2)/N(2) selectivity was 1.9; after UV-ozone exposure, the permeability decreased to 127 barrer while the selectivity increased to 5.4. The free volume depth profile of the SiO(x) layer was investigated by novel slow positron beam. The results show that free volume size increased with the depth, yet the degree of siloxane conversion to SiO(x) does not affect the amount of free volume.

Modelling of wildlife migrations and its economic impacts

NASA Astrophysics Data System (ADS)

Myšková, Kateřina; Žák, Jaroslav

2013-10-01

Natural wildlife migrations are often disrupted by the construction of line structures, especially freeways. Various overpasses and underpasses (migration objects) are being designed to enable species to pass through line structures. The newly developed original procedure for the quantification of the utility of migration objects (migration potentials) and sections of line structures retrieves the deficiencies of the previous ones. The procedure has been developed under bulk information obtained by monitoring migrations using camera system and spy games. The log-normal distribution functions are used. The procedure for the evaluation of the probability of the permeability of the line structures sectors is also presented. The above mentioned procedures and algorithms can be used while planning, preparing, constructing or verifying the measures to assure the permeability of line structures for selected feral species. Using the procedures can significantly reduce financial costs and improve the permeability. When the migration potentials are correctly determined and the whole sector is taken into account for the migrations, some originally designed objects may be found to be redundant and not building them will bring financial savings.

Ion pair reinforced semi-interpenetrating polymer network for direct methanol fuel cell applications.

PubMed

Fang, Chunliu; Julius, David; Tay, Siok Wei; Hong, Liang; Lee, Jim Yang

2012-06-07

This paper describes the synthesis of ion-pair-reinforced semi-interpenetrating polymer networks (SIPNs) as proton exchange membranes (PEMs) for the direct methanol fuel cells (DMFCs). Specifically, sulfonated poly(2,6-dimethyl-1,4-phenylene oxide) (SPPO), a linear polymer proton source, was immobilized in a brominated PPO (BPPO) network covalently cross-linked by ethylenediamine (EDA). The immobilization of SPPO in the SIPN network was accomplished not only by the usual means of mechanical interlocking but also by ion pair formation between the sulfonic acid groups of SPPO and the amine moieties formed during the cross-linking reaction of BPPO with EDA. Through the ion pair interactions, the immobilization of SPPO polymer in the BPPO network was made more effective, resulting in a greater uniformity of sulfonic acid cluster distribution in the membrane. The hydrophilic amine-containing cross-links also compensated for some of the decrease in proton conductivity caused by ion pair formation. The SIPN membranes prepared as such showed good proton conductivity, low methanol permeability, good mechanical properties, and dimensional stability. Consequently, the PPO based SIPN membranes were able to deliver a higher maximum power density than Nafion, demonstrating the potential of the SIPN structure for PEM designs.

Targeted Delivery of Ubiquitin-Conjugated BH3 Peptide-Based Mcl-1 Inhibitors into Cancer Cells

PubMed Central

2015-01-01

BH3 peptides are key mediators of apoptosis and have served as the lead structures for the development of anticancer therapeutics. Previously, we reported the application of a simple cysteine-based side chain cross-linking chemistry to NoxaBH3 peptides that led to the generation of the cross-linked NoxaBH3 peptides with increased cell permeability and higher inhibitory activity against Mcl-1 (Muppidi, A., Doi, K., Edwardraja, S., Drake, E. J., Gulick, A. M., Wang, H.-G., Lin, Q. (2012) J. Am. Chem. Soc.134, 1473422920569). To deliver cross-linked NoxaBH3 peptides selectively into cancer cells for enhanced efficacy and reduced systemic toxicity, here we report the conjugation of the NoxaBH3 peptides with the extracellular ubiquitin, a recently identified endogenous ligand for CXCR4, a chemokine receptor overexpressed in cancer cells. The resulting ubiquitin-NoxaBH3 peptide conjugates showed increased inhibitory activity against Mcl-1 and selective killing of the CXCR4-expressing cancer cells. The successful delivery of the NoxaBH3 peptides by ubiquitin into cancer cells suggests that the ubiquitin/CXCR4 axis may serve as a general route for the targeted delivery of anticancer agents. PMID:24410055

Optimized polymer enhanced foam flooding for ordinary heavy oil reservoir after cross-linked polymer flooding.

PubMed

Sun, Chen; Hou, Jian; Pan, Guangming; Xia, Zhizeng

2016-01-01

A successful cross-linked polymer flooding has been implemented in JD reservoir, an ordinary heavy oil reservoir with high permeability zones. For all that, there are still significant volumes of continuous oil remaining in place, which can not be easily extracted due to stronger vertical heterogeneity. Considering selective plugging feature, polymer enhanced foam (PEF) flooding was taken as following EOR technology for JD reservoir. For low cost and rich source, natural gas was used as foaming gas in our work. In the former work, the surfactant systems CEA/FSA1 was recommended as foam agent for natural gas foam flooding after series of compatibility studies. Foam performance evaluation experiments showed that foaming volume reached 110 mL, half-life time reached 40 min, and dimensionless filter coefficient reached 1.180 when CEA/FSA1 reacted with oil produced by JD reservoir. To compare the recovery efficiency by different EOR technologies, series of oil displacement experiments were carried out in a parallel core system which contained cores with relatively high and low permeability. EOR technologies concerned in our work include further cross-linked polymer (C-P) flooding, surfactant-polymer (S-P) flooding, and PEF flooding. Results showed that PEF flooding had the highest enhanced oil recovery of 19.2 % original oil in place (OOIP), followed by S-P flooding (9.6 % OOIP) and C-P flooding (6.1 % OOIP). Also, produced liquid percentage results indicated PEF flooding can efficiently promote the oil recovery in the lower permeability core by modifying the injection profile.

Use of novel chitosan hydrogels for chemical tissue bonding of autologous chondral transplants.

PubMed

Gittens, Jamila; Haleem, Amgad M; Grenier, Stephanie; Smyth, Niall A; Hannon, Charles P; Ross, Keir A; Torzilli, Peter A; Kennedy, John G

2016-07-01

The objective of this study was to evaluate the effect of chemical tissue bonding (CTB) on adhesion strength, fluid permeability, and cell viability across a cartilaginous graft-host interface in an in vitro autologous chondral transplant (ACT) model. Chitosan-based cross-linkers; Chitosan-Rose Bengal [Chi-RB (Ch-ABC)], Chitosan-Genipin [Chi-GP (Ch-ABC)], and Chitosan-Rose Bengal-Genipin [Chi-RB-GP (Ch-ABC)] were applied to bovine immature cartilage explants after pre-treatment with surface degrading enzyme, Chondroitinase-ABC (Ch-ABC). Adhesion strength, fluid permeability and cell viability were assessed via mechanical push-out shear testing, fluid transport and live/dead cell staining, respectively. All three chitosan-based cross-linkers significantly increased the adhesion strength at the graft-host interface, however, only a statistically significant decrease in fluid permeability was noted in Chi-GP (Ch-ABC) specimen compared to untreated controls. Cell viability was maintained for 7 days of culture across all three treatment groups. These results show the potential clinical relevance of novel chitosan-based hydrogels in enhancing tissue integration and reducing synovial fluid penetration after ACT procedures in diarthoidal joints such as the knee and ankle. © 2015 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 34:1139-1146, 2016. © 2015 Orthopaedic Research Society. Published by Wiley Periodicals, Inc.

Innovative computational tools for reducing exploration risk through integration of water-rock interactions and magnetotelluric surveys

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

Moore, Joseph

2017-04-20

Mapping permeability distributions in geothermal reservoirs is essential for reducing the cost of geothermal development. To avoid the cost and sampling bias of measuring permeability directly through drilling, we require remote methods of imaging permeability such as geophysics. Electrical resistivity (or its inverse, conductivity) is one of the most sensitive geophysical properties known to reflect long range fluid interconnection and thus the likelihood of permeability. Perhaps the most widely applied geophysical methods for imaging subsurface resistivity is magnetotellurics (MT) due to its relatively great penetration depths. A primary goal of this project is to confirm through ground truthing at existingmore » geothermal systems that MT resistivity structure interpreted integratively is capable of revealing permeable fluid pathways into geothermal systems.« less

Liquid-permeable electrode

DOEpatents

Folser, George R.

1980-01-01

Electrodes for use in an electrolytic cell, which are liquid-permeable and have low electrical resistance and high internal surface area are provided of a rigid, porous, carbonaceous matrix having activated carbon uniformly embedded throughout. The activated carbon may be catalyzed with platinum for improved electron transfer between electrode and electrolyte. Activated carbon is mixed with a powdered thermosetting phenolic resin and compacted to the desired shape in a heated mold to melt the resin and form the green electrode. The compact is then heated to a pyrolyzing temperature to carbonize and volatilize the resin, forming a rigid, porous structure. The permeable structure and high internal surface area are useful in electrolytic cells where it is necessary to continuously remove the products of the electrochemical reaction.

Complementary analyses of hollow cylindrical unioriented permanent magnet (HCM) with high permeability external layer

NASA Astrophysics Data System (ADS)

Lobo, Carlos M. S.; Tosin, Giancarlo; Baader, Johann E.; Colnago, Luiz A.

2017-10-01

In this article, several studies based on analytical expressions and computational simulations on Hollow Cylindrical Magnets with an external soft ferromagnetic material (HCM magnets) are presented. Electromagnetic configurations, as well as permanent-magnet-based structures, are studied in terms of magnetic field strength and homogeneity. Permanent-magnet-based structures are further analyzed in terms of the anisotropy of the magnetic permeability. It was found that the HCM magnets produce a highly homogeneous magnetic field as long as the magnetic material is isotropic. The dependency of the magnetic field strength and homogeneity in terms of the anisotropy of the magnetic permeability is also explored here. These magnets can potentially be used in medium-resolution NMR spectrometers and high-field NMR spectrometers.

Investigation of properties of high-performance fiber-reinforced concrete : very early strength, toughness, permeability, and fiber distribution : final report.

DOT National Transportation Integrated Search

2017-01-01

Concrete cracking, high permeability, and leaking joints allow for intrusion of harmful solutions, resulting in concrete deterioration and corrosion of reinforcement in structures. The development of durable, high-performance concretes with limited c...

Surface resistivity as an alternative for rapid chloride permeability test of hardened concrete : [technical summary].

DOT National Transportation Integrated Search

2015-03-01

Kansas experiences harsh winters that require frequent use of de-icing salts, making it : critical to the long-term durability of concrete structures that the permeability is kept : under control. Under current KDOT specification, the Rapid Chloride ...

Using soft computing techniques to predict corrected air permeability using Thomeer parameters, air porosity and grain density

NASA Astrophysics Data System (ADS)

Nooruddin, Hasan A.; Anifowose, Fatai; Abdulraheem, Abdulazeez

2014-03-01

Soft computing techniques are recently becoming very popular in the oil industry. A number of computational intelligence-based predictive methods have been widely applied in the industry with high prediction capabilities. Some of the popular methods include feed-forward neural networks, radial basis function network, generalized regression neural network, functional networks, support vector regression and adaptive network fuzzy inference system. A comparative study among most popular soft computing techniques is presented using a large dataset published in literature describing multimodal pore systems in the Arab D formation. The inputs to the models are air porosity, grain density, and Thomeer parameters obtained using mercury injection capillary pressure profiles. Corrected air permeability is the target variable. Applying developed permeability models in recent reservoir characterization workflow ensures consistency between micro and macro scale information represented mainly by Thomeer parameters and absolute permeability. The dataset was divided into two parts with 80% of data used for training and 20% for testing. The target permeability variable was transformed to the logarithmic scale as a pre-processing step and to show better correlations with the input variables. Statistical and graphical analysis of the results including permeability cross-plots and detailed error measures were created. In general, the comparative study showed very close results among the developed models. The feed-forward neural network permeability model showed the lowest average relative error, average absolute relative error, standard deviations of error and root means squares making it the best model for such problems. Adaptive network fuzzy inference system also showed very good results.

Reservoir studies with geostatistics to forecast performance

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

Tang, R.W.; Behrens, R.A.; Emanuel, A.S.

1991-05-01

In this paper example geostatistics and streamtube applications are presented for waterflood and CO{sub 2} flood in two low-permeability sandstone reservoirs. Thy hybrid approach of combining fine vertical resolution in cross-sectional models with streamtubes resulted in models that showed water channeling and provided realistic performance estimates. Results indicate that the combination of detailed geostatistical cross sections and fine-grid streamtube models offers a systematic approach for realistic performance forecasts.

Selective molecular transport through the protein shell of a bacterial microcompartment organelle

DOE PAGES

Chowdhury, Chiranjit; Chun, Sunny; Pang, Allan; ...

2015-02-23

Bacterial microcompartments are widespread prokaryotic organelles that have important and diverse roles ranging from carbon fixation to enteric pathogenesis. Current models for microcompartment function propose that their outer protein shell is selectively permeable to small molecules, but whether a protein shell can mediate selective permeability and how this occurs are unresolved questions. In this paper, biochemical and physiological studies of structure-guided mutants are used to show that the hexameric PduA shell protein of the 1,2-propanediol utilization (Pdu) microcompartment forms a selectively permeable pore tailored for the influx of 1,2-propanediol (the substrate of the Pdu microcompartment) while restricting the efflux ofmore » propionaldehyde, a toxic intermediate of 1,2-propanediol catabolism. Crystal structures of various PduA mutants provide a foundation for interpreting the observed biochemical and phenotypic data in terms of molecular diffusion across the shell. Finally and overall, these studies provide a basis for understanding a class of selectively permeable channels formed by nonmembrane proteins.« less

Hemocompatible polyethersulfone/polyurethane composite membrane for high-performance antifouling and antithrombotic dialyzer.

PubMed

Yin, Zehua; Cheng, Chong; Qin, Hui; Nie, Chuanxiong; He, Chao; Zhao, Changsheng

2015-01-01

Researches on blood purification membranes are fuelled by diverse clinical needs, such as hemodialysis, hemodiafiltration, hemofiltration, plasmapheresis, and plasma collection. To approach high-performance dialyzer, the integrated antifouling and antithrombotic properties are highly necessary for the design/modification of advanced artificial membranes. In this study, we propose and demonstrate that the physical blend of triblock polyurethane (PU) and polyethersulfone (PES) may advance the performance of hemodialysis membranes with greatly enhanced blood compatibility. It was found that the triblock PU could be blended with PES at high ratio owing to their excellent miscibility. The surfaces of the PES/PU composite membranes were characterized using attenuated total reflectance-Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, water contact angle measurement, and surface ζ-potentials. The results indicated that the membrane surfaces were assembled with hydrophilic segregation layer owing to the migration of amphiphilic PU segments during membrane preparation, which might confer the composite membranes with superior hemocompatibility. The cross-section scanning electron microscopy images of the composite membranes exhibited structure transformation from finger-like structure to sponge-like structure, which indicated that the composite membrane had tunable porosity and permeability. The further ultrafiltration experiments indicated that the composite membranes showed increased permeability and excellent antifouling ability. The blood compatibility observation indicated that PES/PU composite membranes owned decreased protein adsorption, suppressed platelet adhesion, and prolonged plasma recalcification time. These results indicated that the PES/PU composite membranes exhibited enhanced antifouling and antithrombotic properties than the pristine PES membrane. The strategy may forward the fabrication of blood compatible composite membranes for clinical blood dialysis by using the various functional miscible polymers. © 2014 Wiley Periodicals, Inc.

A 3D object-based model to simulate highly-heterogeneous, coarse, braided river deposits

NASA Astrophysics Data System (ADS)

Huber, E.; Huggenberger, P.; Caers, J.

2016-12-01

There is a critical need in hydrogeological modeling for geologically more realistic representation of the subsurface. Indeed, widely-used representations of the subsurface heterogeneity based on smooth basis functions such as cokriging or the pilot-point approach fail at reproducing the connectivity of high permeable geological structures that control subsurface solute transport. To realistically model the connectivity of high permeable structures of coarse, braided river deposits, multiple-point statistics and object-based models are promising alternatives. We therefore propose a new object-based model that, according to a sedimentological model, mimics the dominant processes of floodplain dynamics. Contrarily to existing models, this object-based model possesses the following properties: (1) it is consistent with field observations (outcrops, ground-penetrating radar data, etc.), (2) it allows different sedimentological dynamics to be modeled that result in different subsurface heterogeneity patterns, (3) it is light in memory and computationally fast, and (4) it can be conditioned to geophysical data. In this model, the main sedimentological elements (scour fills with open-framework-bimodal gravel cross-beds, gravel sheet deposits, open-framework and sand lenses) and their internal structures are described by geometrical objects. Several spatial distributions are proposed that allow to simulate the horizontal position of the objects on the floodplain as well as the net rate of sediment deposition. The model is grid-independent and any vertical section can be computed algebraically. Furthermore, model realizations can serve as training images for multiple-point statistics. The significance of this model is shown by its impact on the subsurface flow distribution that strongly depends on the sedimentological dynamics modeled. The code will be provided as a free and open-source R-package.

The permeability of fractured rocks in pressurised volcanic and geothermal systems.

PubMed

Lamur, A; Kendrick, J E; Eggertsson, G H; Wall, R J; Ashworth, J D; Lavallée, Y

2017-07-21

The connectivity of rocks' porous structure and the presence of fractures influence the transfer of fluids in the Earth's crust. Here, we employed laboratory experiments to measure the influence of macro-fractures and effective pressure on the permeability of volcanic rocks with a wide range of initial porosities (1-41 vol. %) comprised of both vesicles and micro-cracks. We used a hand-held permeameter and hydrostatic cell to measure the permeability of intact rock cores at effective pressures up to 30 MPa; we then induced a macro-fracture to each sample using Brazilian tensile tests and measured the permeability of these macro-fractured rocks again. We show that intact rock permeability increases non-linearly with increasing porosity and decreases with increasing effective pressure due to compactional closure of micro-fractures. Imparting a macro-fracture both increases the permeability of rocks and their sensitivity to effective pressure. The magnitude of permeability increase induced by the macro-fracture is more significant for dense rocks. We finally provide a general equation to estimate the permeability of intact and fractured rocks, forming a basis to constrain fluid flow in volcanic and geothermal systems.

Evaluation of Surface Resistivity Measurements as an Alternative to the Rapid Chloride Permeability Test for Quality Assurance and Acceptance - Implementation Report

DOT National Transportation Integrated Search

2012-10-01

Many contracting agencies currently use permeability specifications in portland cement concrete (PCC) pavements and structures. This project followed the implementation of the surface resistivity test (TR 233) on a field project in Louisiana. Additio...

Water Quality Performance of Three Side-by-Side Permeable Pavement Surface Materials: Three Year Update

EPA Science Inventory

Communities are increasingly installing structural low impact development (LID) practices to mange stormwater and reduce pollutant loads associated with stormwater runoff. Permeable pavement is a LID practice that has limited research on working-scale, side-by-side performance o...

Evaluation of surface resistivity measurements as an alternative to the rapid chloride permeability test for quality assurance and acceptance.

DOT National Transportation Integrated Search

2011-07-01

Many entities currently use permeability specifications in portland cement concrete (PCC) pavements and structures. This project investigated the use of a surface resistivity device as an indication of concretes ability to resist chloride ion pene...

Fracture network topology and characterization of structural permeability

NASA Astrophysics Data System (ADS)

Hansberry, Rowan; King, Rosalind; Holford, Simon

2017-04-01

There are two fundamental requirements for successful geothermal development: elevated temperatures at accessible depths, and a reservoir from which fluids can be extracted. The Australian geothermal sector has successfully targeted shallow heat, however, due in part to the inherent complexity of targeting permeability, obtaining adequate flow rates for commercial production has been problematic. Deep sedimentary aquifers are unlikely to be viable geothermal resources due to the effects of diagenetic mineral growth on rock permeability. Therefore, it is likely structural permeability targets, exploiting natural or induced fracture networks will provide the primary means for fluid flow in geothermal, as well as unconventional gas, reservoirs. Recent research has focused on the pattern and generation of crustal stresses across Australia, while less is known about the resultant networks of faults, joints, and veins that can constitute interconnected sub-surface permeability pathways. The ability of a fracture to transmit fluid is controlled by the orientation and magnitude of the in-situ stress field that acts on the fracture walls, rock strength, and pore pressure, as well as fracture properties such as aperture, orientation, and roughness. Understanding the distribution, orientation and character of fractures is key to predicting structural permeability. This project focuses on extensive mapping of fractures over various scales in four key Australian basins (Cooper, Otway, Surat and Perth) with the potential to host geothermal resources. Seismic attribute analysis is used in concert with image logs from petroleum wells, and field mapping to identify fracture networks that are usually not resolved in traditional seismic interpretation. We use fracture network topology to provide scale-invariant characterisation of fracture networks from multiple data sources to assess similarity between data sources, and fracture network connectivity. These results are compared with other permeability indicators such as drilling fluid losses, and pore pressure measurements. Initial work with these techniques has led to new developments in our ability to image subsurface faults and fractures at a variety of scales from independent datasets. We establish a strong relationship between features identified using seismic attribute analysis and interpreted natural fractures. However, care must be taken to use these methods in a case-by-case basis, as controls on fracture distribution and orientation can vary significantly with both regional and local influences. These results outline and effective method by which structural permeability can be assessed with existing petroleum datasets. However, unlike the broad stress field, mapping fracture orientation and characteristics within the Australian Continent is complicated as the distribution, geometry, areal extent and connectivity of fracture networks can vary significantly.

Using environmental features to model highway crossing behavior of Canada lynx in the Southern Rocky Mountains.

DOT National Transportation Integrated Search

2015-07-21

Carnivores are particularly sensitive to reductions in population connectivity caused by human disturbance and habitat fragmentation. Permeability of transportation corridors to carnivore movements is central to species conservation given the large s...

Metamaterial for Radar Frequencies

DTIC Science & Technology

2012-09-01

Circuit Board RAM Radar Absorbing Material RCS Radar Cross Section SNR Signal-to-Noise Ratio SNG Single-Negative SRR Split Ring Resonator...although some can be single-negative ( SNG ). DNG refers to material with simultaneous negative real parts of the permittivity r  and permeability

Effect of lactobacilli on paracellular permeability in the gut.

PubMed

Ahrne, Siv; Hagslatt, Marie-Louise Johansson

2011-01-01

Paracellular permeability is determined by the complex structures of junctions that are located between the epithelial cells. Already in 1996, it was shown that the human probiotic strain Lactobacillus plantarum 299v and the rat-originating strain Lactobacillus reuteri R2LC could reduce this permeability in a methotrexate-induced colitis model in the rat. Subsequently, many animal models and cell culture systems have shown indications that lactobacilli are able to counteract increased paracellular permeability evoked by cytokines, chemicals, infections, or stress. There have been few human studies focusing on the effect of lactobacilli on intestinal paracellular permeability but recently it has been shown that they could influence the tight junctions. More precisely, short-term administration of L. plantarum WCSF1 to healthy volunteers increased the relocation of occludin and ZO-1 into the tight junction area between duodenal epithelial cells.

Induction of apoptosis and reversal of permeability glycoprotein-mediated multidrug resistance of MCF-7/ADM by ginsenoside Rh2.

PubMed

Zhang, Hui; Gong, Jian; Zhang, Huilai; Kong, Di

2015-01-01

Multidrug resistance is a phenomenon that cancer cells develop a cross-resistant phenotype against several unrelated drugs, and permeability glycoprotein derived from the overexpression of multidrug resistance gene 1 has been taken as the most significant cause of multidrug resistance. In the present study, ginsenoside Rh2 was used to reverse permeability glycoprotein-mediated multidrug resistance of MCF-7/ADM cell line. Effects of ginsenoside Rh2 on the apoptotic process and caspase-3 activity of MCF-7 and MCF-7/ADM cell lines were determined using flow cytometry and microplate reader. Methyl thiazolyl tetrazolium test was conducted to assess the IC50 values of ginsenoside Rh2 and adriamycin on MCF-7 and MCF-7/ADM cultures; Rhodamin 123 assay was used to assess the retention of permeability glycoprotein after ginsenoside Rh2 treatment; flow cytometry and real time polymerase chain reaction were used to determine the expression levels of permeability glycoprotein and multidrug resistance gene 1 in drug-resistant cells and their parental cells after exposure to ginsenoside Rh2. The results showed that ginsenoside Rh2, except for inducing apoptosis, had the ability to reverse multidrug resistance in MCF-7/ADM cell line without changing the expression levels of permeability glycoprotein and multidrug resistance gene 1. Our findings provided some valuable information for the application of ginsenoside Rh2 in cancer therapy, especially for multidrug resistance reversal in clinic.

The effect of platelets on fibrin gel structure formed in the presence of recombinant factor VIIa in hemophilia plasma and in plasma from a patient with Glanzmann thrombasthenia.

PubMed

He, S; Ekman, G Jacobsson; Hedner, U

2005-02-01

Fibrin gel structure has been shown to be dependent on the thrombin concentration as well as the rate of thrombin generation. Accordingly, factor VIII (FVIII)- and FIX-deficient plasma (hemophilia A and B) form loose fibrin clots with high permeability constants. By adding rFVIIa in vitro to FVIII-deficient plasma containing platelets (frozen and thawed), the fibrin gel permeability constant normalized, indicating that extra rFVIIa (1.2 microg mL(-1) or higher) induced a tight fibrin structure. Thrombin generation is highly dependent on the number of platelets, and in this study it was demonstrated that the addition of rFVIIa (5 microg mL(-1)) normalizes the fibrin gel permeability in samples containing platelets (frozen-thawed) in numbers of at least down to 20 x 10(6) mL(-1). The effect of rFVIIa was not observed when unfrozen platelets instead of frozen-thawed platelets were added. Neither was any effect on the fibrin permeability seen, in the presence of annexin V, known to block the effect of phospholipids on the platelet surface. This indicates an important role of platelet phospholipids for the effect of rFVIIa. A similar effect on the fibrin permeability of rFVIIa was observed when added to platelet-rich plasma from a patient with Glanzmann thrombasthenia. Recombinant FVIIa has been found to induce hemostasis in patients with hemophilia and inhibitors against FVIII/FIX as well as in patients with Glanzmann thrombasthenia, indicating the importance of the formation of a tight fibrin gel structure, more resistant against premature proteolysis, for maintaining hemostasis. In conclusion, the addition of rFVIIa (5 microg mL(-1)) also substantially decreased the permeability constant of fibrin gels formed in FVIII-deficient plasma in the presence of low numbers of frozen-thawed platelets (down to 20 x 10(6) mL(-1)). A similar pattern was obtained in plasma from a Glanzmann patient. No effect was found in the presence of unfrozen instead of frozen-thawed platelets. Annexin V blocked any effect of rFVIIa. A normalization of the overall fibrinolysis potential (OFP) during the same condition supports the effect of rFVIIa on the fibrin permeability in the presence of a limited number of platelets.

Claudins and the Modulation of Tight Junction Permeability

PubMed Central

Günzel, Dorothee

2013-01-01

Claudins are tight junction membrane proteins that are expressed in epithelia and endothelia and form paracellular barriers and pores that determine tight junction permeability. This review summarizes our current knowledge of this large protein family and discusses recent advances in our understanding of their structure and physiological functions. PMID:23589827

Evaluation of Surface Resistivity Measurements as an Alternative to the Rapid Chloride Permeability Test for Quality Assurance and Acceptance : Tech Summary

DOT National Transportation Integrated Search

2012-10-01

Many contracting agencies currently use permeability specifi cations in Portland cement concrete (PCC) : pavements and structures. This project followed the implementation of the surface resistivity test TR 233 : on a fi eld project in Louisiana. Add...

Silicon-based Porous Ceramics via Freeze Casting of Preceramic Polymers

NASA Astrophysics Data System (ADS)

Naviroj, Maninpat

Freeze casting is a technique for processing porous materials that has drawn significant attention for its effectiveness in producing a variety of tailorable pore structures for ceramics, metals, and polymers. With freeze casting, pores are generated based on a solidification process where ice crystals act as a sacrificial template which can eventually be sublimated to create pores. While the majority of freeze-casting studies have been performed using conventional ceramic suspensions, this work explores an alternative processing route by freeze casting with preceramic polymer solutions. Significant differences exist between freeze casting of a particulate suspension and a polymeric solution. These changes affect the processing method, solidification behavior, and pore structure, thereby introducing new challenges and possibilities for the freeze-casting technique. The first part of this study explored the processing requirements involved with freeze casting of preceramic polymers, along with methods to control the resulting pore structure. Solvent choice, freezing front velocity, and polymer concentration were used as processing variables to manipulate the pore structures. A total of seven organic solvents were freeze cast with a polymethylsiloxane preceramic polymer to produce ceramics with isotropic, dendritic, prismatic, and lamellar pore morphologies. Changes in freezing front velocity and polymer concentration were shown to influence pore size, shape, and connectivity. Differences between suspension- and solution-based samples freeze cast under equivalent conditions were also investigated. Certain solidification microstructures were strongly affected by the presence of suspended particles, creating differences between pore structures generated from the same solvents. Additionally, processing of solution-based samples were found to be the more facile technique. Compressive strength and water permeability of dendritic and lamellar structures were analyzed to determine functional differences between the pore structures. Results show that dendritic structures were up to 30 times stronger, while lamellar structures provided higher permeability constants. A change in freezing front velocity was shown to significantly affect permeability but not compressive strength. Finally, improved pore alignment along the freezing direction was achieved by controlling the nucleation and growth of solvent crystals through the use of a grain-selection template. Dendritic samples freeze cast with a template showed substantial increase in pore alignment, as determined by image analysis and permeability tests, with the permeability constant increasing by up to 6-fold when compared to a control sample.

Nanoclay cross-linked semi-IPN silk sericin/poly(NIPAm/LMSH) nanocomposite hydrogel: An outstanding antibacterial wound dressing.

PubMed

Yang, Chaochao; Xue, Rui; Zhang, Qingsong; Yang, Shulin; Liu, Pengfei; Chen, Li; Wang, Ke; Zhang, Xiaoyong; Wei, Yen

2017-12-01

High antibacterial and skin-like hydrogels have always been the perfect wound dressing for human to protect wound from infection. Here, based on silk sericin, we design a series of nanoclay lithium magnesium silicate hydrate (LMSH) cross-linked semi-IPN sericin/poly(NIPAm/LMSH) (HSP) nanocomposite hydrogels and demonstrate advantages in serving as antibacterial wound dressing in comparison with gauze. Firstly, the effect of mass ratios of sericin/(sericin+NIPAm) upon pore structure, feasibility of mechanics and gas permeability of HSP nanocomposite hydrogels were evaluated. Then, the relationship between nanocomposite hydrogel and histological/antimicrobial properties was systematically analyzed. It was found that, the introduction of sericin increased internal pore size, leading to obvious transition from honeycomb to layered structure. Furthermore, as mass ratio of sericin/(sericin+NIPAm) is 20%, the wound healing area treated with nanocomposite hydrogels at 6th day reached up to 83%, 3 times of gauze, and almost recovered at 13th day. Especially, antibacterial mechanism can be thought to be the results that the macromolecular sericin embedded in the nanocomposite hydrogel adsorbed bacteria by charge interaction and micromolecular sericin dissociating out from nanocomposite hydrogels can be adsorbed onto bacteria. Copyright © 2017 Elsevier B.V. All rights reserved.

From nano- to macro-engineering of oxide-encapsulated-nanoparticles for harsh reactions: one-step organization via cross-linking molecules.

PubMed

Zhang, Qiaofei; Zhao, Guofeng; Zhang, Zhiqiang; Han, Lupeng; Fan, Songyu; Chai, Ruijuan; Li, Yakun; Liu, Ye; Huang, Jun; Lu, Yong

2016-09-29

A strategy of "macro-micro-nano" organization is reported for embedding oxide-encapsulated-nanoparticles onto monolithic substrates in one-step with the aid of molecularly defined cross-linking agents. Such catalysts, with enhanced heat/mass transfer and high permeability, are qualified for several harsh reaction processes such as CH 4 /VOC abatement, gas-phase hydrogenation of dimethyl oxalate and oxidative dehydrogenation of ethane.

Permeability and Microstructure of Suspension Plasma-Sprayed YSZ Electrolytes for SOFCs on Various Substrates

NASA Astrophysics Data System (ADS)

Marr, Michael; Kesler, Olivera

2012-12-01

Yttria-stabilized zirconia electrolyte coatings for solid oxide fuel cells were deposited by suspension plasma spraying using a range of spray conditions and a variety of substrates, including finely structured porous stainless steel disks and cathode layers on stainless steel supports. Electrolyte permeability values and trends were found to be highly dependent on which substrate was used. The most gas-tight electrolyte coatings were those deposited directly on the porous metal disks. With this substrate, permeability was reduced by increasing the torch power and reducing the stand-off distance to produce dense coating microstructures. On the substrates with cathodes, electrolyte permeability was reduced by increasing the stand-off distance, which reduced the formation of segmentation cracks and regions of aligned and concentrated porosity. The formation mechanisms of the various permeability-related coating features are discussed and strategies for reducing permeability are presented. The dependences of electrolyte deposition efficiency and surface roughness on process conditions and substrate properties are also presented.

Stochastic simulation of uranium migration at the Hanford 300 Area.

PubMed

Hammond, Glenn E; Lichtner, Peter C; Rockhold, Mark L

2011-03-01

This work focuses on the quantification of groundwater flow and subsequent U(VI) transport uncertainty due to heterogeneity in the sediment permeability at the Hanford 300 Area. U(VI) migration at the site is simulated with multiple realizations of stochastically-generated high resolution permeability fields and comparisons are made of cumulative water and U(VI) flux to the Columbia River. The massively parallel reactive flow and transport code PFLOTRAN is employed utilizing 40,960 processor cores on DOE's petascale Jaguar supercomputer to simultaneously execute 10 transient, variably-saturated groundwater flow and U(VI) transport simulations within 3D heterogeneous permeability fields using the code's multi-realization simulation capability. Simulation results demonstrate that the cumulative U(VI) flux to the Columbia River is less responsive to fine scale heterogeneity in permeability and more sensitive to the distribution of permeability within the river hyporheic zone and mean permeability of larger-scale geologic structures at the site. Copyright © 2010 Elsevier B.V. All rights reserved.

Influence of capillary end effects on steady-state relative permeability estimates from direct pore-scale simulations

NASA Astrophysics Data System (ADS)

Guédon, Gaël Raymond; Hyman, Jeffrey De'Haven; Inzoli, Fabio; Riva, Monica; Guadagnini, Alberto

2017-12-01

We investigate and characterize the influence of capillary end effects on steady-state relative permeabilities obtained in pore-scale numerical simulations of two-phase flows. Our study is motivated by the observation that capillary end effects documented in two-phase laboratory-scale experiments can significantly influence permeability estimates. While numerical simulations of two-phase flows in reconstructed pore-spaces are increasingly employed to characterize relative permeabilities, a phenomenon which is akin to capillary end effects can also arise in such analyses due to the constraints applied at the boundaries of the computational domain. We profile the relative strength of these capillary end effects on the calculation of steady-state relative permeabilities obtained within randomly generated porous micro-structures using a finite volume-based two-phase flow solver. We suggest a procedure to estimate the extent of the regions influenced by these capillary end effects, which in turn allows for the alleviation of bias in the estimation of relative permeabilities.

Gas permeability of ice-templated, unidirectional porous ceramics

NASA Astrophysics Data System (ADS)

Seuba, Jordi; Deville, Sylvain; Guizard, Christian; Stevenson, Adam J.

2016-01-01

We investigate the gas flow behavior of unidirectional porous ceramics processed by ice-templating. The pore volume ranged between 54% and 72% and pore size between 2.9 ?m and 19.1 ?m. The maximum permeability (?? m?) was measured in samples with the highest total pore volume (72%) and pore size (19.1 ?m). However, we demonstrate that it is possible to achieve a similar permeability (?? m?) at 54% pore volume by modification of the pore shape. These results were compared with those reported and measured for isotropic porous materials processed by conventional techniques. In unidirectional porous materials tortuosity (?) is mainly controlled by pore size, unlike in isotropic porous structures where ? is linked to pore volume. Furthermore, we assessed the applicability of Ergun and capillary model in the prediction of permeability and we found that the capillary model accurately describes the gas flow behavior of unidirectional porous materials. Finally, we combined the permeability data obtained here with strength data for these materials to establish links between strength and permeability of ice-templated materials.

Modeling fine-scale geological heterogeneity--examples of sand lenses in tills.

PubMed

Kessler, Timo Christian; Comunian, Alessandro; Oriani, Fabio; Renard, Philippe; Nilsson, Bertel; Klint, Knud Erik; Bjerg, Poul Løgstrup

2013-01-01

Sand lenses at various spatial scales are recognized to add heterogeneity to glacial sediments. They have high hydraulic conductivities relative to the surrounding till matrix and may affect the advective transport of water and contaminants in clayey till settings. Sand lenses were investigated on till outcrops producing binary images of geological cross-sections capturing the size, shape and distribution of individual features. Sand lenses occur as elongated, anisotropic geobodies that vary in size and extent. Besides, sand lenses show strong non-stationary patterns on section images that hamper subsequent simulation. Transition probability (TP) and multiple-point statistics (MPS) were employed to simulate sand lens heterogeneity. We used one cross-section to parameterize the spatial correlation and a second, parallel section as a reference: it allowed testing the quality of the simulations as a function of the amount of conditioning data under realistic conditions. The performance of the simulations was evaluated on the faithful reproduction of the specific geological structure caused by sand lenses. Multiple-point statistics offer a better reproduction of sand lens geometry. However, two-dimensional training images acquired by outcrop mapping are of limited use to generate three-dimensional realizations with MPS. One can use a technique that consists in splitting the 3D domain into a set of slices in various directions that are sequentially simulated and reassembled into a 3D block. The identification of flow paths through a network of elongated sand lenses and the impact on the equivalent permeability in tills are essential to perform solute transport modeling in the low-permeability sediments. © 2012, The Author(s). Groundwater © 2012, National Ground Water Association.

Complementary analyses of hollow cylindrical unioriented permanent magnet (HCM) with high permeability external layer.

PubMed

Lobo, Carlos M S; Tosin, Giancarlo; Baader, Johann E; Colnago, Luiz A

2017-10-01

In this article, several studies based on analytical expressions and computational simulations on Hollow Cylindrical Magnets with an external soft ferromagnetic material (HCM magnets) are presented. Electromagnetic configurations, as well as permanent-magnet-based structures, are studied in terms of magnetic field strength and homogeneity. Permanent-magnet-based structures are further analyzed in terms of the anisotropy of the magnetic permeability. It was found that the HCM magnets produce a highly homogeneous magnetic field as long as the magnetic material is isotropic. The dependency of the magnetic field strength and homogeneity in terms of the anisotropy of the magnetic permeability is also explored here. These magnets can potentially be used in medium-resolution NMR spectrometers and high-field NMR spectrometers. Copyright © 2017 Elsevier Inc. All rights reserved.

Discontinuities in effective permeability due to fracture percolation

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

Hyman, Jeffrey De'Haven; Karra, Satish; Carey, James William

Motivated by a triaxial coreflood experiment with a sample of Utica shale where an abrupt jump in permeability was observed, possibly due to the creation of a percolating fracture network through the sample, we perform numerical simulations based on the experiment to characterize how the effective permeability of otherwise low-permeability porous media depends on fracture formation, connectivity, and the contrast between the fracture and matrix permeabilities. While a change in effective permeability due to fracture formation is expected, the dependence of its magnitude upon the contrast between the matrix permeability and fracture permeability and the fracture network structure is poorlymore » characterized. We use two different high-fidelity fracture network models to characterize how effective permeability changes as percolation occurs. The first is a dynamic two-dimensional fracture propagation model designed to mimic the laboratory settings of the experiment. The second is a static three-dimensional discrete fracture network (DFN) model, whose fracture and network statistics are based on the fractured sample of Utica shale. Once the network connects the inflow and outflow boundaries, the effective permeability increases non-linearly with network density. In most networks considered, a jump in the effective permeability was observed when the embedded fracture network percolated. We characterize how the magnitude of the jump, should it occur, depends on the contrast between the fracture and matrix permeabilities. For small contrasts between the matrix and fracture permeabilities the change is insignificant. However, for larger contrasts, there is a substantial jump whose magnitude depends non-linearly on the difference between matrix and fracture permeabilities. A power-law relationship between the size of the jump and the difference between the matrix and fracture permeabilities is observed. In conclusion, the presented results underscore the importance of fracture network topology on the upscaled properties of the porous medium in which it is embedded.« less

Discontinuities in effective permeability due to fracture percolation

DOE PAGES

Hyman, Jeffrey De'Haven; Karra, Satish; Carey, James William; ...

2018-01-31

Motivated by a triaxial coreflood experiment with a sample of Utica shale where an abrupt jump in permeability was observed, possibly due to the creation of a percolating fracture network through the sample, we perform numerical simulations based on the experiment to characterize how the effective permeability of otherwise low-permeability porous media depends on fracture formation, connectivity, and the contrast between the fracture and matrix permeabilities. While a change in effective permeability due to fracture formation is expected, the dependence of its magnitude upon the contrast between the matrix permeability and fracture permeability and the fracture network structure is poorlymore » characterized. We use two different high-fidelity fracture network models to characterize how effective permeability changes as percolation occurs. The first is a dynamic two-dimensional fracture propagation model designed to mimic the laboratory settings of the experiment. The second is a static three-dimensional discrete fracture network (DFN) model, whose fracture and network statistics are based on the fractured sample of Utica shale. Once the network connects the inflow and outflow boundaries, the effective permeability increases non-linearly with network density. In most networks considered, a jump in the effective permeability was observed when the embedded fracture network percolated. We characterize how the magnitude of the jump, should it occur, depends on the contrast between the fracture and matrix permeabilities. For small contrasts between the matrix and fracture permeabilities the change is insignificant. However, for larger contrasts, there is a substantial jump whose magnitude depends non-linearly on the difference between matrix and fracture permeabilities. A power-law relationship between the size of the jump and the difference between the matrix and fracture permeabilities is observed. In conclusion, the presented results underscore the importance of fracture network topology on the upscaled properties of the porous medium in which it is embedded.« less

Structural analysis characterization of permeability pathways across reservoir-seal interface - South-Eastern Utah; Results from integrated sedimentological, structural, and geochemical studies.

NASA Astrophysics Data System (ADS)

Petrie, E. S.; Evans, J. P.; Richey, D.; Flores, S.; Barton, C.; Mozley, P.

2015-12-01

Sedimentary rocks in the San Rafael Swell, Utah, were deformed by Laramide compression and subsequent Neogene extension. We evaluate the effect of fault damage zone morphology as a function of structural position, and changes in mechanical stratigraphy on the distribution of secondary minerals across the reservoir-seal pair of the Navajo Sandstone and overlying Carmel Formation. We decipher paleo-fluid migration and examine the effect faults and fractures have on reservoir permeability and efficacy of top seal for a range of geo-engineering applications. Map-scale faults have an increased probability of allowing upward migration of fluids along the fault plane and within the damage zone, potentially bypassing the top seal. Field mapping, mesoscopic structural analyses, petrography, and geochemical observations demonstrate that fault zone thickness increases at structural intersections, fault relay zones, fault-related folds, and fault tips. Higher densities of faults with meters of slip and dense fracture populations are present in relay zones relative to single, discrete faults. Curvature analysis of the San Rafael monocline and fracture density data show that fracture density is highest where curvature is highest in the syncline hinge and near faults. Fractures cross the reservoir-seal interface where fracture density is highest and structural diagensis includes mineralization events and bleaching and calcite and gypsum mineralization. The link between fracture distributions and structural setting implys that transmissive fractures have predictable orientations and density distributions. At the m- to cm- scale, deformation-band faults and joints in the Navajo Sandstone penetrate the reservoir-seal interface and transition into open-mode fractures in the caprock seal. Scanline analysis and petrography of veins provide evidence for subsurface mineralization and fracture reactivation, suggesting that the fractures act as loci for fluid flow through time. Heterolithic caprock seals with variable fracture distributions and morphology highlight the strong link between the variation in material properties and the response to changing stress conditions. The variable connectivity of fractures and the changes in fracture density plays a critical role in subsurface fluid flow.

Cross-well 4-D resistivity tomography localizes the oil-water encroachment front during water flooding

NASA Astrophysics Data System (ADS)

Zhang, J.; Revil, A.

2015-04-01

The early detection of the oil-water encroachment front is of prime interest during the water flooding of an oil reservoir to maximize the production of oil and to avoid the oil-water encroachment front to come too close to production wells. We propose a new 4-D inversion approach based on the Gauss-Newton approach to invert cross-well resistance data. The goal of this study is to image the position of the oil-water encroachment front in a heterogeneous clayey sand reservoir. This approach is based on explicitly connecting the change of resistivity to the petrophysical properties controlling the position of the front (porosity and permeability) and to the saturation of the water phase through a petrophysical resistivity model accounting for bulk and surface conductivity contributions and saturation. The distributions of the permeability and porosity are also inverted using the time-lapse resistivity data in order to better reconstruct the position of the oil water encroachment front. In our synthetic test case, we get a better position of the front with the by-products of porosity and permeability inferences near the flow trajectory and close to the wells. The numerical simulations show that the position of the front is recovered well but the distribution of the recovered porosity and permeability is only fair. A comparison with a commercial code based on a classical Gauss-Newton approach with no information provided by the two-phase flow model fails to recover the position of the front. The new approach could be used for the time-lapse monitoring of various processes in both geothermal fields and oil and gas reservoirs using a combination of geophysical methods.

Numerical Simulations of Melting-Crystallisation Processes at the Boundaries Between Magma Oceans and Solid Mantle

NASA Astrophysics Data System (ADS)

Bolrão, D. P.; Rozel, A.; Morison, A.; Labrosse, S.; Tackley, P. J.

2017-12-01

The idea that the Earth had a global magma ocean, mostly created by impacts, core formation, radiogenic and tidal heating, is well accepted nowadays. When this ocean starts to crystallise, if the melt is denser than the solid, a basal magma ocean is created below the solid part. These two magma oceans influence the dynamics and evolution of solid mantle. Near the boundaries, the vertical flow in the solid part creates a topography. If this topography is destroyed by melting/crystallisation processes in a time scale much shorter than the time needed to adjust the topography by viscous relaxation, then matter can cross the boundary. In this case, the boundary is said to be permeable. On the other hand, if this time is longer, matter cannot cross and the boundary is said impermeable. This permeability is defined by a non-dimensional phase change number, φ, introduced by Deguen, 2013. This φ is the ratio of the two timescales mentioned, and defines a permeable boundary when φ « 1, and an impermeable one when φ » 1. To understand the impact of magma oceans on the dynamics of the solid mantle, we use the convection code StagYY, with a 2D spherical annulus geometry, to compute the convection of the solid part. Our results show different convection behaviours depending on the type of boundary chosen. For the permeable case, we investigate the thermo-compositional evolution of the solid domain, explicitly taking into account the compositional evolution of the magma oceans. Reference: Deguen, R. Thermal convection in a spherical shell with melting/freezing at either or both of its boundaries. Journal of Earth Science, Vol. 24, No. 5, p. 669-682, 2013. doi: 10.1007/s12583-013-0364-8

Structural and stratigraphic framework and spatial distribution of permeability of the Atlantic coastal plain, North Carolina to New York

USGS Publications Warehouse

Brown, Philip Monroe; Miller, James A.; Swain, Frederick Morrill

1972-01-01

This report describes and interprets the results of a detailed subsurface mapping program undertaken in that part of the Atlantic Coastal Plain which extends from the South Carolina and North Carolina border through Long Island, N.Y. Data obtained from more than 2,200 wells are analyzed. Seventeen chronostratigraphic units are mapped in the subsurface. They range in age from Jurassic(?) to post-Miocene. The purpose of the mapping program was to determine the external and internal geometry of mappable chronostratigraphic units and to derive and construct a permeability-distribution network for each unit based upon contrasts in the textures and compositions of its contained sediments. The report contains a structure map and a combined isopach, lithofacies, and permeability-distribution map for each of the chronostratigraphic units delineated in the subsurface. In addition, it contains a map of the top of the basement surface. These maps, together with 36 stratigraphic cross sections, present a three-dimensional view of the regional subsurface hydrogeology. They provide focal points of reference for a discussion of regional tectonics, structure, stratigraphy, and permeability distribution. Taken together and in chronologic sequence, the maps constitute a detailed sedimentary model, the first such model to be constructed for the middle Atlantic Coastal Plain. The chronostratigraphic units mapped record a structural history dominated by lateral and vertical movement along a system of intersecting hinge zones. Taphrogeny, related to transcurrent faulting, is the dominant type of deformation that controlled the geometry of the sedimentary model. Twelve of the seventeen chronostratigraphic units mapped have depositional alinements and thickening trends that are independent of the present-day configuration of the underlying basement surface. These 12 units, classified as genetically unrooted units, are assigned to a first-order tectonic stage. A structural model is proposed whose alinements of positive and negative structural features are accordant with the depositional geometry of the chronostratigraphic units assigned to this tectonic stage. The dominant features of the structural model are northeast-plunging half grabens arranged en echelon and bordered by northeast-plunging fault-block anticlines. Tension-type hinge zones that strike north lie athwart the half grabens. Five of the seventeen chronostratigraphic units mapped have depositional alinements and thickening trends that are accordant with the present-day configuration of the underlying basement surface. These five units, classified as genetically rooted units, are assigned to a second-order tectonic stage. A structural model is proposed whose alinements of positive and negative features are accordant with the depositional geometry of the chronostratigraphic units assigned to this tectonic stage. The dominant feature of this model is a graben that stands tangential to southeast-plunging asymmetrical anticlines. Tension-type hinge zones that strike northeast lie athwart the graben. To account for the semiperiodic realinement of structural features that has characterized the history of the region and as a working hypothesis, we propose that the dominant tectonic element, which is present in the area between north Florida and Long Island, N.Y., is a unit-structural block, a ?basement? block, bounded by wrench-fault zones. We propose that forces derived principally from the rotation and precession of the earth act on the unit-structural block and deform it. Two tectonic models are proposed. One model is compatible with the structural and sedimentary geometries that are associated with chronostratigraphic units assigned to a first-order tectonic stage. It features tension-type hinge zones that strike north and shear-type hinge zones that strike northeast. The other model is compatible with the structural and sedimentary geometries associated with chronostratigraphi

Effect of amine structure on CO2 capture by polymeric membranes.

PubMed

Taniguchi, Ikuo; Kinugasa, Kae; Toyoda, Mariko; Minezaki, Koki

2017-01-01

Poly(amidoamine)s (PAMAMs) incorporated into a cross-linked poly(ethylene glycol) exhibited excellent CO 2 separation properties over H 2 . However, the CO 2 permeability should be increased for practical applications. Monoethanolamine (MEA) used as a CO 2 determining agent in the current CO 2 capture technology at demonstration scale was readily immobilized in poly(vinyl alcohol) (PVA) matrix by solvent casting of aqueous mixture of PVA and the amine. The resulting polymeric membranes can be self-standing with the thickness above 3 μm and the amine fraction less than 80 wt%. The gas permeation properties were examined at 40 °C and under 80% relative humidity. The CO 2 separation performance increased with increase of the amine content in the polymeric membranes. When the amine fraction was 80 wt%, the CO 2 permeability coefficient of MEA containing membrane was 604 barrer with CO 2 selectivity of 58.5 over H 2 , which was much higher than the PAMAM membrane (83.7 barrer and 51.8, respectively) under the same operation conditions. On the other hand, ethylamine (EA) was also incorporated into PVA matrix to form a thin membrane. However, the resulting polymeric membranes exhibited slight CO 2 -selective gas permeation properties. The hydroxyl group of MEA was crucial for high CO 2 separation performance.

Controlling the morphology and performance of FO membrane via adjusting the atmosphere humidity during casting procedure

NASA Astrophysics Data System (ADS)

Zuo, Hao-Ran; Cao, Gui-Ping; Wang, Meng; Zhang, Huan-Huan; Song, Chen-Chen; Fang, Xu; Wang, Tao

2018-03-01

Forward osmosis (FO) has received great interest for its considerable potential in a wide range of fields. In this work, the morphology and performance of FO membrane were regulated by adjusting the atmosphere humidity (HC) of casting procedure. The polysulfone support layer was casted under various atmosphere humidity levels ranging from 40% to 80%. By multi-techniques such as SEM, AFM, and XPS, it was proved that the atmosphere humidity had modified the surface morphology and thickness of the skin layer in support layer, which contributed up to 90% of the structure parameter, resulting in distinct morphology, thickness, and cross-linking degree of active layer. The active layer with sparse bead-like wrinkles on the smooth surface of support layer casted at HC = 65% showed the highest water permeability [26.9 (L/m2 h MPa)] and considerable low salt permeability [0.0390 (L/m2 h)]. It was found that the water flux of FO-65 was 27% and 46% higher than that of FO-80 in AL-DS and AL-FS mode, respectively, and the salt rejection was as high as 98%. Our work highlighted the importance of considering the effect of atmosphere humidity during casting when design an FO membrane for appropriate performance.

Effect of amine structure on CO2 capture by polymeric membranes

PubMed Central

Taniguchi, Ikuo; Kinugasa, Kae; Toyoda, Mariko; Minezaki, Koki

2017-01-01

Abstract Poly(amidoamine)s (PAMAMs) incorporated into a cross-linked poly(ethylene glycol) exhibited excellent CO2 separation properties over H2. However, the CO2 permeability should be increased for practical applications. Monoethanolamine (MEA) used as a CO2 determining agent in the current CO2 capture technology at demonstration scale was readily immobilized in poly(vinyl alcohol) (PVA) matrix by solvent casting of aqueous mixture of PVA and the amine. The resulting polymeric membranes can be self-standing with the thickness above 3 μm and the amine fraction less than 80 wt%. The gas permeation properties were examined at 40 °C and under 80% relative humidity. The CO2 separation performance increased with increase of the amine content in the polymeric membranes. When the amine fraction was 80 wt%, the CO2 permeability coefficient of MEA containing membrane was 604 barrer with CO2 selectivity of 58.5 over H2, which was much higher than the PAMAM membrane (83.7 barrer and 51.8, respectively) under the same operation conditions. On the other hand, ethylamine (EA) was also incorporated into PVA matrix to form a thin membrane. However, the resulting polymeric membranes exhibited slight CO2-selective gas permeation properties. The hydroxyl group of MEA was crucial for high CO2 separation performance. PMID:29383045

Machine learning framework for analysis of transport through complex networks in porous, granular media: A focus on permeability

NASA Astrophysics Data System (ADS)

van der Linden, Joost H.; Narsilio, Guillermo A.; Tordesillas, Antoinette

2016-08-01

We present a data-driven framework to study the relationship between fluid flow at the macroscale and the internal pore structure, across the micro- and mesoscales, in porous, granular media. Sphere packings with varying particle size distribution and confining pressure are generated using the discrete element method. For each sample, a finite element analysis of the fluid flow is performed to compute the permeability. We construct a pore network and a particle contact network to quantify the connectivity of the pores and particles across the mesoscopic spatial scales. Machine learning techniques for feature selection are employed to identify sets of microstructural properties and multiscale complex network features that optimally characterize permeability. We find a linear correlation (in log-log scale) between permeability and the average closeness centrality of the weighted pore network. With the pore network links weighted by the local conductance, the average closeness centrality represents a multiscale measure of efficiency of flow through the pore network in terms of the mean geodesic distance (or shortest path) between all pore bodies in the pore network. Specifically, this study objectively quantifies a hypothesized link between high permeability and efficient shortest paths that thread through relatively large pore bodies connected to each other by high conductance pore throats, embodying connectivity and pore structure.

Enhanced graphene oxide membranes and methods for making same

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

Shin, Yongsoon; Gotthold, David W.; Fifield, Leonard S.

A method for making a graphene oxide membrane and a resulting free-standing graphene oxide membrane that provides desired qualities of water permeability and selectivity at larger sizes, thinner cross sections, and with increased ruggedness as compared to existing membranes and processes.

Convective mixing in vertically-layered porous media: The linear regime and the onset of convection

NASA Astrophysics Data System (ADS)

Ghorbani, Zohreh; Riaz, Amir; Daniel, Don

2017-08-01

We study the effect of permeability heterogeneity on the stability of gravitationally unstable, transient, diffusive boundary layers in porous media. Permeability is taken to vary periodically in the horizontal plane normal to the direction of gravity. In contrast to the situation for vertical permeability variation, the horizontal perturbation structures are multimodal. We therefore use a two-dimensional quasi-steady eigenvalue analysis as well as a complementary initial value problem to investigate the stability behavior in the linear regime, until the onset of convection. We find that thick permeability layers enhance instability compared with thin layers when heterogeneity is increased. On the contrary, for thin layers the instability is weakened progressively with increasing heterogeneity to the extent that the corresponding homogeneous case is more unstable. For high levels of heterogeneity, we find that a small change in the permeability field results in large variations in the onset time of convection, similar to the instability event in the linear regime. However, this trend does not persist unconditionally because of the reorientation of vorticity pairs due to the interaction of evolving perturbation structures with heterogeneity. Consequently, an earlier onset of instability does not necessarily imply an earlier onset of convection. A resonant amplification of instability is observed within the linear regime when the dominant perturbation mode is equal to half the wavenumber of permeability variation. On the other hand, a substantial damping occurs when the perturbation mode is equal to the harmonic and sub-harmonic components of the permeability wavenumber. The phenomenon of such harmonic interactions influences both the onset of instability as well as the onset of convection.

Convective mixing in vertically-layered porous media: The linear regime and the onset of convection

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

Ghorbani, Zohreh; Riaz, Amir; Daniel, Don

In this paper, we study the effect of permeability heterogeneity on the stability of gravitationally unstable, transient, diffusive boundary layers in porous media. Permeability is taken to vary periodically in the horizontal plane normal to the direction of gravity. In contrast to the situation for vertical permeability variation, the horizontal perturbation structures are multimodal. We therefore use a two-dimensional quasi-steady eigenvalue analysis as well as a complementary initial value problem to investigate the stability behavior in the linear regime, until the onset of convection. We find that thick permeability layers enhance instability compared with thin layers when heterogeneity is increased.more » On the contrary, for thin layers the instability is weakened progressively with increasing heterogeneity to the extent that the corresponding homogeneous case is more unstable. For high levels of heterogeneity, we find that a small change in the permeability field results in large variations in the onset time of convection, similar to the instability event in the linear regime. However, this trend does not persist unconditionally because of the reorientation of vorticity pairs due to the interaction of evolving perturbation structures with heterogeneity. Consequently, an earlier onset of instability does not necessarily imply an earlier onset of convection. A resonant amplification of instability is observed within the linear regime when the dominant perturbation mode is equal to half the wavenumber of permeability variation. On the other hand, a substantial damping occurs when the perturbation mode is equal to the harmonic and sub-harmonic components of the permeability wavenumber. Finally, the phenomenon of such harmonic interactions influences both the onset of instability as well as the onset of convection.« less

Convective mixing in vertically-layered porous media: The linear regime and the onset of convection

DOE PAGES

Ghorbani, Zohreh; Riaz, Amir; Daniel, Don

2017-08-02

In this paper, we study the effect of permeability heterogeneity on the stability of gravitationally unstable, transient, diffusive boundary layers in porous media. Permeability is taken to vary periodically in the horizontal plane normal to the direction of gravity. In contrast to the situation for vertical permeability variation, the horizontal perturbation structures are multimodal. We therefore use a two-dimensional quasi-steady eigenvalue analysis as well as a complementary initial value problem to investigate the stability behavior in the linear regime, until the onset of convection. We find that thick permeability layers enhance instability compared with thin layers when heterogeneity is increased.more » On the contrary, for thin layers the instability is weakened progressively with increasing heterogeneity to the extent that the corresponding homogeneous case is more unstable. For high levels of heterogeneity, we find that a small change in the permeability field results in large variations in the onset time of convection, similar to the instability event in the linear regime. However, this trend does not persist unconditionally because of the reorientation of vorticity pairs due to the interaction of evolving perturbation structures with heterogeneity. Consequently, an earlier onset of instability does not necessarily imply an earlier onset of convection. A resonant amplification of instability is observed within the linear regime when the dominant perturbation mode is equal to half the wavenumber of permeability variation. On the other hand, a substantial damping occurs when the perturbation mode is equal to the harmonic and sub-harmonic components of the permeability wavenumber. Finally, the phenomenon of such harmonic interactions influences both the onset of instability as well as the onset of convection.« less

Physical heterogeneity control on effective mineral dissolution rates

NASA Astrophysics Data System (ADS)

Jung, Heewon; Navarre-Sitchler, Alexis

2018-04-01

Hydrologic heterogeneity may be an important factor contributing to the discrepancy in laboratory and field measured dissolution rates, but the governing factors influencing mineral dissolution rates among various representations of physical heterogeneity remain poorly understood. Here, we present multiple reactive transport simulations of anorthite dissolution in 2D latticed random permeability fields and link the information from local grid scale (1 cm or 4 m) dissolution rates to domain-scale (1m or 400 m) effective dissolution rates measured by the flux-weighted average of an ensemble of flow paths. We compare results of homogeneous models to heterogeneous models with different structure and layered permeability distributions within the model domain. Chemistry is simplified to a single dissolving primary mineral (anorthite) distributed homogeneously throughout the domain and a single secondary mineral (kaolinite) that is allowed to dissolve or precipitate. Results show that increasing size in correlation structure (i.e. long integral scales) and high variance in permeability distribution are two important factors inducing a reduction in effective mineral dissolution rates compared to homogeneous permeability domains. Larger correlation structures produce larger zones of low permeability where diffusion is an important transport mechanism. Due to the increased residence time under slow diffusive transport, the saturation state of a solute with respect to a reacting mineral approaches equilibrium and reduces the reaction rate. High variance in permeability distribution favorably develops large low permeability zones that intensifies the reduction in mixing and effective dissolution rate. However, the degree of reduction in effective dissolution rate observed in 1 m × 1 m domains is too small (<1% reduction from the corresponding homogeneous case) to explain several orders of magnitude reduction observed in many field studies. When multimodality in permeability distribution is approximated by high permeability variance in 400 m × 400 m domains, the reduction in effective dissolution rate increases due to the effect of long diffusion length scales through zones with very slow reaction rates. The observed scale dependence becomes complicated when pH dependent kinetics are compared to the results from pH independent rate constants. In small domains where the entire domain is reactive, faster anorthite dissolution rates and slower kaolinite precipitation rates relative to pH independent rates at far-from-equilibrium conditions reduce the effective dissolution rate by increasing the saturation state. However, in large domains where less- or non-reactive zones develop, higher kaolinite precipitation rates in less reactive zones increase the effective anorthite dissolution rates relative to the rates observed in pH independent cases.

Influence of chain ordering on the selectivity of dipalmitoylphosphatidylcholine bilayer membranes for permeant size and shape.

PubMed Central

Xiang, T X; Anderson, B D

1998-01-01

The effects of lipid chain packing and permeant size and shape on permeability across lipid bilayers have been investigated in gel and liquid crystalline dipalmitoylphosphatidylcholine (DPPC) bilayers by a combined NMR line-broadening/dynamic light scattering method using seven short-chain monocarboxylic acids (formic acid, acetic acid, propionic acid, butyric acid, valeric acid, isovaleric acid, and trimethylacetic acid) as permeants. The experimental permeability coefficients are compared with the predictions of a bulk solubility diffusion model in which the bilayer membrane is represented as a slab of bulk hexadecane. Deviations of the observed permeability coefficients (Pm) from the values predicted from solubility diffusion theory (Po) lead to the determination of a correction factor, the permeability decrement f (= Pm/Po), to account for the effects of chain ordering. The natural logarithm of f has been found to correlate linearly with the inverse of the bilayer free surface area with slopes of 25 +/- 2, 36 +/- 3, 45 +/- 8, 32 +/- 12, 33 +/- 4, 49 +/- 12, and 75 +/- 6 A2 for formic acid, acetic acid, propionic acid, butyric acid, valeric acid, isovaleric acid, and trimethylacetic acid, respectively. The slope, which measures the sensitivity of the permeability coefficient of a given permeant to bilayer chain packing, exhibits an excellent linear correlation (r = 0.94) with the minimum cross-sectional area of the permeant and a poor correlation (r = 0.59) with molecular volume, suggesting that in the bilayer interior the permeants prefer to move with their long principal axis along the bilayer normal. Based on these studies, a permeability model combining the effects of bilayer chain packing and permeant size and shape on permeability across lipid membranes is developed. PMID:9826590

Cross-linked polyelectrolyte for direct methanol fuel cells applications based on a novel sulfonated cross-linker

NASA Astrophysics Data System (ADS)

Li, Mingyu; Zhang, Gang; Xu, Shuai; Zhao, Chengji; Han, Miaomiao; Zhang, Liyuan; Jiang, Hao; Liu, Zhongguo; Na, Hui

2014-06-01

A novel type of cross-linked proton exchange membrane of lower methanol permeation and high proton conductivity is prepared, based on a newly synthesized sulfonated cross-linker: carboxyl terminated benzimidazole trimer bearing sulfonic acid groups (s-BI). Compared to membranes cross-linked with non-sulfonated cross-linker (BI), SPEEK/s-BI-n membranes show higher IEC values and proton conductivities. Meanwhile, oxidative stability and mechanical property of SPEEK/s-BI-n membranes are obviously improved. Among SPEEK/s-BI-n membranes, SPEEK/s-BI-2 exhibits high proton conductivity, low swelling ratio (0.122 S cm-1 and 15.2% at 60 °C, respectively) and low methanol permeability coefficient. These results imply that the cross-linked membranes prepared with the newly sulfonated cross-linker are promising for the direct methanol fuel cells (DMFCs) application.

Fault-controlled permeability and fluid flow in low-porosity crystalline rocks: an example from naturally fractured geothermal systems in the Southern Andes

NASA Astrophysics Data System (ADS)

Arancibia, G.; Roquer, T.; Sepúlveda, J.; Veloso, E. A.; Morata, D.; Rowland, J. V.

2017-12-01

Fault zones can control the location, emplacement, and evolution of economic mineral deposits and geothermal systems by acting as barriers and/or conduits to crustal fluid flow (e.g. magma, gas, oil, hydro-geothermal and groundwater). The nature of the fault control permeability is critical in the case of fluid flow into low porosity/permeability crystalline rocks, since structural permeability provides the main hydraulic conductivity to generate a natural fractured system. However, several processes accompanying the failure of rocks (i.e. episodic permeability given by cycling ruptures, mineral precipitation from fluids in veins, dissolution of minerals in the vicinity of a fracture) promote a complex time-dependent and enhancing/reducing fault-controlled permeability. We propose the Southern Volcanic Zone (Southern Andes, Chile) as a case study to evaluate the role of the structural permeability in low porosity crystalline rocks belonging to the Miocene North Patagonian Batholith. Recently published studies propose a relatively well-constrained first-order role of two active fault systems, the arc-parallel (NS to NNE trending) Liquiñe Ofqui Fault System and the arc-oblique (NW trending) Andean Transverse Fault Zones, in fluid flow at crustal scales. We now propose to examine the Liquiñe ( 39°S) and Maihue ( 40°S) areas as sites of interaction between these fault systems, in order to evaluate a naturally fractured geothermal system. Preliminary results indicate upwelling of thermal water directly from fractured granite or from fluvial deposits overlying granitoids. Measured temperatures of thermal springs suggest a low- to medium-enthalpy system, which could potentially be harnessed for use in geothermal energy applications (e.g. heating, wood dryer and green house), which are much needed in Southern Chile. Future work will aim to examine the nature of structural permeability from the regional to the microscopic scale connecting the paleo- and current- fluid flow through the fractured media. Results will contribute to a better understanding of geothermal systems in the Andean tectonic setting and of naturally fractured reservoirs in low-porosity crystalline rocks around the world. Acknowledgments: This work is funded by CEGA-FONDAP/CONICYT #15090013 and VRI-PUENTE #P1703/2017.

A Spatial Correlation Model of Permeability on the Columbia River Plateau

NASA Astrophysics Data System (ADS)

Jayne, R., Jr.; Pollyea, R. M.

2017-12-01

This study presents a spatial correlation model of regional scale permeability variability within the Columbia River Basalt Group (CRBG). The data were compiled from the literature, and include 893 aquifer test results from 598 individual wells. In order to quantify the spatial variation of permeability within the CRBG, three experimental variograms (two horizontal and one vertical) are calculated and then fit with a linear combination of mathematical models. The horizontal variograms show there is a 4.5:1 anisotropy ratio for the permeability correlation structure with a long-range correlation of 35 km at N40°E. The km-scale range of these variograms suggests that there is regional control on permeability within the CRBG. One plausible control on the permeability distribution is that rapid crustal loading during CRBG emplacement ( 80% over 1M years) resulted in an isostatic response where the Columbia Plateau had previously undergone subsidence. To support this hypothesis, we calculate a 200 m moving average of all permeability values with depth. This calculation shows that permeability generally follows a systematic decay until 1,100 m depth, beyond which the 200 m moving average permeability increases 3 orders of magnitude. Since basalt fracture networks govern permeability on Columbia River Plateau, this observation is consistent with basal flexure causing tensile stress that counteract lithostatic loading, thus maintaining higher than expected permeability at depth within the Columbia River Basalt Group. These results may have important implications for regional CRBG groundwater management, as well as engineered reservoirs for carbon capture and sequestration and nuclear waste storage.

When good statistical models of aquifer heterogeneity go right: The impact of aquifer permeability structures on 3D flow and transport

NASA Astrophysics Data System (ADS)

Jankovic, I.; Maghrebi, M.; Fiori, A.; Dagan, G.

2017-02-01

Natural gradient steady flow of mean velocity U takes place in heterogeneous aquifers of random logconductivity Y = lnK , characterized by the univariate PDF f(Y) and autocorrelation ρY. Solute transport is analyzed through the Breakthrough Curve (BTC) at planes at distance x from the injection plane. The study examines the impact of permeability structures sharing same f(Y) and ρY, but differing in higher order statistics (integral scales of variograms of Y classes) upon the numerical solution of flow and transport. Flow and transport are solved for 3D structures, rather than the 2D models adopted in most of previous works. We considered a few permeability structures, including the widely employed multi-Gaussian, the connected and disconnected fields introduced by Zinn and Harvey [2003] and a model characterized by equipartition of the correlation scale among Y values. We also consider the impact of statistical anisotropy of Y, the shape of ρY and local diffusion. The main finding is that unlike 2D, the prediction of the BTC of ergodic plumes by numerical and analytical models for different structures is quite robust, displaying a seemingly universal behavior, and can be used with confidence in applications. However, as a prerequisite the basic parameters KG (the geometric mean), σY2 (the logconductivity variance) and I (the horizontal integral scale of ρY) have to be identified from field data. The results suggest that narrowing down the gap between the BTCs in applications can be achieved by obtaining Kef (the effective conductivity) or U independently (e.g. by pumping tests), rather than attempting to characterize the permeability structure beyond f(Y) and ρY.

Stress concentrations at structural discontinuities in active fault zones in the western United States: Implications for permeability and fluid flow in geothermal fields

USGS Publications Warehouse

Siler, Drew; Hinz, Nicholas H.; Faulds, James E.

2018-01-01

Slip can induce concentration of stresses at discontinuities along fault systems. These structural discontinuities, i.e., fault terminations, fault step-overs, intersections, bends, and other fault interaction areas, are known to host fluid flow in ore deposition systems, oil and gas reservoirs, and geothermal systems. We modeled stress transfer associated with slip on faults with Holocene-to-historic slip histories at the Salt Wells and Bradys geothermal systems in western Nevada, United States. Results show discrete locations of stress perturbation within discontinuities along these fault systems. Well field data, surface geothermal manifestations, and subsurface temperature data, each a proxy for modern fluid circulation in the fields, indicate that geothermal fluid flow is focused in these same areas where stresses are most highly perturbed. These results suggest that submeter- to meter-scale slip on these fault systems generates stress perturbations that are sufficiently large to promote slip on an array of secondary structures spanning the footprint of the modern geothermal activity. Slip on these secondary faults and fractures generates permeability through kinematic deformation and allows for transmission of fluids. Still, mineralization is expected to seal permeability along faults and fractures over time scales that are generally shorter than either earthquake recurrence intervals or the estimated life span of geothermal fields. This suggests that though stress perturbations resulting from fault slip are broadly important for defining the location and spatial extent of enhanced permeability at structural discontinuities, continual generation and maintenance of flow conduits throughout these areas are probably dependent on the deformation mechanism(s) affecting individual structures.

Towards Practical Carbonation Prediction and Modelling for Service Life Design of Reinforced Concrete Structures

NASA Astrophysics Data System (ADS)

Ekolu, O. S.

2015-11-01

Amongst the scientific community, the interest in durability of concrete structures has been high for quite a long time of over 40 years. Of the various causes of degradation of concrete structures, corrosion is the most widespread durability problem and carbonation is one of the two causes of steel reinforcement corrosion. While much scientific understanding has been gained from the numerous carbonation studies undertaken over the past years, it is still presently not possible to accurately predict carbonation and apply it in design of structures. This underscores the complex nature of the mechanisms as influenced by several interactive factors. Based on critical literature and some experience of the author, it is found that there still exist major challenges in establishing a mathematical constitutive relation for realistic carbonation prediction. While most current models employ permeability /diffusion as the main model property, analysis shows that the most practical material property would be compressive strength, which has a low coefficient of variation of 20% compared to 30 to 50% for permeability. This important characteristic of compressive strength, combined with its merit of simplicity and data availability at all stages of a structure's life, promote its potential use in modelling over permeability. By using compressive strength in carbonation prediction, the need for accelerated testing and permeability measurement can be avoided. This paper attempts to examine the issues associated with carbonation prediction, which could underlie the current lack of a sound established prediction method. Suggestions are then made for possible employment of different or alternative approaches.

A PERMEABLE ACTIVE AMENDMENT CONCRETE (PAAC) FOR CONTAMINANT REMEDIATION AND EROSION CONTROL

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

Knox, A.; Paller, M.; Dixon, K.

2012-06-29

The final project report for SEED SERDP ER - 2134 describes the development of permeable active amendment concrete (PAAC), which was evaluated through four tasks: 1) development of PAAC; 2) assessment of PAAC for contaminant removal; 3) evaluation of promising PAAC formulations for potential environmental impacts; and 4) assessment of the hydraulic, physical, and structural properties of PAAC. Conventional permeable concrete (often referred to as pervious concrete) is concrete with high porosity as a result of an extensive and interconnected void content. It is made from carefully controlled amounts of water and cementitious materials used to create a paste thatmore » forms a coating around aggregate particles. The mixture has a substantial void content (e.g., 15% - 25%) that results in a highly permeable structure that drains quickly. In PAAC, the aggregate material is partly replaced by chemically-active amendments that precipitate or adsorb contaminants in water that flows through the concrete interstices. PAAC combines the relatively high structural strength, ample void space, and water permeability of pervious concrete with the contaminant sequestration ability of chemically-active amendments to produce a new material with superior durability and ability to control contaminant mobility. The high surface area provided by the concrete interstices in PAAC provides significant opportunity for contaminants to react with the amendments incorporated into the concrete matrix. PAAC has the potential to immobilize a large variety of organic and inorganic contaminants by incorporating different active sequestering agents including phosphate materials (rock phosphate), organoclays, zeolite, and lime individually or in combinations.« less

High permeable microporous structured carbon counter electrode assisted by polystyrene sphere for fully printable perovskite solar cells

NASA Astrophysics Data System (ADS)

Tao, Haijun; Li, Yongtao; Zhang, Chuanxiang; Wang, Kang; Wang, Jiayue; Tan, Bin; Han, Linxuan; Tao, Jie

2018-03-01

The permeability of the carbon counter electrode (CCE) is critical to the HTM-free fully printable perovskite solar cells. In this work, we report a CCE assisted by polystyrene spheres (PS-spheres) as pore-forming agent to gain microporous structure for a better permeability. Due to its decomposition temperature at 400 °C, the porous structure is obtained in the carbon layer easily. By optimization towards the contents of PS-spheres in CCE, the filling rate of perovskite solution and the photovoltaic performance of the device have been significantly improved. Using this method, an average efficiency enhancement of 22% has been obtained for HTM-free fully printable perovskite solar cells, resulting in a better fill rate of CH3NH3PbI3 and an efficiency of 4.49%. This kind of CCE with the advantages of simple, easy preparation process and well performance, show excellent potential application in perovskite solar cells.

Quantitative imaging of intracellular signaling for personalized pancreatic cancer therapy in an in vivo avatar (Conference Presentation)

NASA Astrophysics Data System (ADS)

Samkoe, Kimberley S.; Schultz, Emily; Park, Yeonjae; Fischer, Dawn; Pogue, Brian W.; Smith, Kerrington; Tichauer, Kenneth M.; Gibbs, Summer L.

2017-02-01

Pancreatic ductal adenocarcinomas (PDAC) are notoriously difficult to treat and in general, molecular targeted therapies have failed even when the targeted protein is overexpressed in the tumor tissue. Genetic mutations in extracellular receptors and downstream signaling proteins (i.e., RAS signaling pathway) and convoluted intracellular cross-talk between cell signaling pathways are likely reasons that these promising therapies fail. Monitoring the complex relationship between intracellular protein signaling is difficult and to-date, standard techniques that are used (Western blot, flow cytometry, immunohistochemistry, etc.) are invasive, static and do not accurately represent in vivo structure-function relationships. Here, we describe the development of an in ovo avatar using patient derived tumors grown on the chicken chorioallantoic membrane (CAM) and the novel fluorescence-based Quantitative Protein Expression Tracking (QUIET) methodology to bridge the gap between oncology, genomics and patient outcomes. Previously developed paired-agent imaging, was extended to a three-compartment model system in QUIET, which utilizes three types of imaging agents: novel fluorophore conjugated cell permeable targeted and untargeted small molecule paired-agents, in addition to a tumor perfusion agent that is not cell membrane permeable. We have demonstrated the ability to quantify the intracellular binding domain of a trans-membrane protein in vitro using cell permeable fluorescent agents (erlotinib-TRITC and control isotype-BODIPY FL). In addition, we have demonstrated imaging protocols to simultaneously image up to 6 spectrally distinct organic fluorophores in in ovo avatars using the Nuance EX (Perkin Elmer) and established proof-of-principle intracellular and extracellular protein concentrations of epidermal growth factor receptor using QUIET and traditional paired-agent imaging.

Decision trees to characterise the roles of permeability and solubility on the prediction of oral absorption.

PubMed

Newby, Danielle; Freitas, Alex A; Ghafourian, Taravat

2015-01-27

Oral absorption of compounds depends on many physiological, physiochemical and formulation factors. Two important properties that govern oral absorption are in vitro permeability and solubility, which are commonly used as indicators of human intestinal absorption. Despite this, the nature and exact characteristics of the relationship between these parameters are not well understood. In this study a large dataset of human intestinal absorption was collated along with in vitro permeability, aqueous solubility, melting point, and maximum dose for the same compounds. The dataset allowed a permeability threshold to be established objectively to predict high or low intestinal absorption. Using this permeability threshold, classification decision trees incorporating a solubility-related parameter such as experimental or predicted solubility, or the melting point based absorption potential (MPbAP), along with structural molecular descriptors were developed and validated to predict oral absorption class. The decision trees were able to determine the individual roles of permeability and solubility in oral absorption process. Poorly permeable compounds with high solubility show low intestinal absorption, whereas poorly water soluble compounds with high or low permeability may have high intestinal absorption provided that they have certain molecular characteristics such as a small polar surface or specific topology. Copyright © 2015 Elsevier Masson SAS. All rights reserved.

Effect of Lactobacilli on Paracellular Permeability in the Gut

PubMed Central

Ahrne, Siv; Hagslatt, Marie-Louise Johansson

2011-01-01

Paracellular permeability is determined by the complex structures of junctions that are located between the epithelial cells. Already in 1996, it was shown that the human probiotic strain Lactobacillus plantarum 299v and the rat-originating strain Lactobacillus reuteri R2LC could reduce this permeability in a methotrexate-induced colitis model in the rat. Subsequently, many animal models and cell culture systems have shown indications that lactobacilli are able to counteract increased paracellular permeability evoked by cytokines, chemicals, infections, or stress. There have been few human studies focusing on the effect of lactobacilli on intestinal paracellular permeability but recently it has been shown that they could influence the tight junctions. More precisely, short-term administration of L. plantarum WCSF1 to healthy volunteers increased the relocation of occludin and ZO-1 into the tight junction area between duodenal epithelial cells. PMID:22254077

Octopus microvasculature: permeability to ferritin and carbon.

PubMed

Browning, J

1979-01-01

The permeability of Octopus microvasculature was investigated by intravascular injection of carbon and ferritin. Vessels were tight to carbon while ferritin penetrated the pericyte junction, and was found extravascularly 1-2 min after its introduction. Vesicles occurred rarely in pericytes; fenestrae were absent. The discontinuous endothelial layer did not consitute a permeability barrier. The basement membrane, although retarding the movement of ferritin, was permeable to it; carbon did not penetrate the basement membrane. Evidence indicated that ferritin, and thus similarly sized and smaller water soluble materials, traverse the pericyte junction as a result of bulk fluid flow. Comparisons are made with the convective (or junctional) and slower, diffusive (or vesicular) passage of materials known to occur across the endothelium of continuous capillaries in mammals. Previous macrophysiological determinations concerning the permeability of Octopus vessels are questioned in view of these findings. Possible reasons for some major structural differences in the microcirculatory systems of cephalopods and vertebrates are briefly discussed.

Effects of Ether vs. Ester Linkage on Lipid Bilayer Structure and Water Permeability

PubMed Central

Guler, S. Deren; Ghosh, D. Dipon; Pan, Jianjun; Matthai, John C.; Zeidel, Mark L.; Nagle, John F.; Tristram-Nagle, Stephanie

2009-01-01

The structure and water permeability of bilayers composed of the ether linked lipid, dihexadecylphosphatidylcholine (DHPC), were studied and compared with the ester linked lipid, dipalmitoylphosphaditdylcholine (DPPC). Wide angle x-ray scattering on oriented bilayers in the fluid phase indicate that the area per lipid A is slightly larger for DHPC than for DPPC. Low angle x-ray scattering yields A=65.1Å2 for DHPC at 48°C. LAXS data provide the bending modulus, KC=4.2×10−13erg, and the Hamaker parameter H=7.2×10−14erg for the van der Waals attractive interaction between neighboring bilayers. For the low temperature phases with ordered hydrocarbon chains, we confirm the transition from a tilted Lß’ gel phase to an untilted, interdigitated LßI phase as the sample hydrates at 20°C. Our measurement of water permeability, Pf=0.022 cm/s at 48 °C for fluid phase DHPC is slightly smaller than that of DPPC, (Pf=0.027 cm/s) at 50 °C, consistent with our triple slab theory of permeability. PMID:19416724

Peculiarities of convection and oil maturation in 3D porous medium structure.

NASA Astrophysics Data System (ADS)

Yurie Khachay, Professor; Mindubaev, Mansur

2017-04-01

An important estimation of oil source thickness productivity is to study the thermal influences of magmatic intrusions on the maturation of the organic matter. The heterogeneity of permeability distribution of the reservoir rock and respectively the convection structure provide temperature heterogeneity and different degree of maturity for the oil source material. A numerical algorithm for solving the problem of developed convection in two-dimensional and three-dimensional models of the porous medium, which consists of a system of Darcy equations, heat conduction with convection term and the continuity equation, is developed. Because of the effective values of the coefficients of thermal conductivity, heat capacity, viscosity and permeability of the medium depend from the temperature; the system of equations is nonlinear. For solution we used the dimensionless system of coordinates. For numerical solution we used the longitudinal cross-implicit scheme. The coordinates step for the 3D model had been used constant and equal to H/20, where H=1- dimensionless thickness of porous medium layer. As it is shown from the variants of numerical solution, by the stationary regime of developed convection because of the temperature heterogeneous distribution in the sedimentary reservoir the formation of oil source matter different degree of maturity is possible. That result is very significant for estimation of reservoirs oil-bearing The work was fulfilled by supporting of the Fund of UB RAS, project 1518532. Reference 1. Yurie Khachay and Mansur Mindubaev, 2016, Effect of convective transport in porous media on the conductions of organic matter maturation and generation of hydrocarbons in trap rocks complexes, Energy Procedia. 74 pp.79-83.

Understanding fluid transport through the multiscale pore network of a natural shale

NASA Astrophysics Data System (ADS)

Davy, Catherine; Adler, Pierre; Song, Yang; Nguyen, Thang Kim; Troadec, David; Dhénin, Jean-Francois

2017-04-01

Natural shales have a complex pore structure, which is only partly understood today. In the present contribution, a combination of different techniques is used to get information on three different scales. On each scale, the relevant flow equation is solved and provides input for the flow equation of the next higher scale. More precisely, micro-CT, FIB/SEM (Focused Ion Beam/Scanning Electron Microscopy) and TEM (Transmission Electron Microscopy) provide a full representative 3D pore space on the macroscopic scale, the mesoscale and the nanoscale. The corresponding typical voxel sizes are 0.7 μm, 10 nm and 1 nm, respectively. The porosity on the micro-CT images is 0.5 %, and it is not connected. One can distinguish between the pores, the porous clay matrix and non porous minerals; the volume percentages of these last two phases are 0.6 and 0.395, respectively. Samples of the porous clay matrix were analyzed by FIB/SEM which yields 3D information. They have a porosity ranging from 2 to 6 %. In some of them, the pore space is connected. Finally, TEM provides 2D images with a porosity of about 10 to 25 %. These information were used in the following way to estimate the macroscopic permeability which has been measured independently and found equal to 6 x10-20 m2. At the nanoscopic scale analyzed by 2D TEM, in the absence of 3D images, the pore structure is reconstructed by using a technique based on truncated Gaussian fields. Then, the Stokes equations are solved by using a 3D Lattice Boltzmann method. The resulting velocity field is averaged and this provides the permeability K_n. The permeability of the nanoscale structure varies between 0.7x 10-20 and 1.8x10-19 m2. As expected, the material is anisotropic. At the mesoscale, percolation of the FIB/SEM pore volume occurs only along a single direction. The Stokes equations are again solved by the same method and the mesoscopic permeability Km varies between 3.3 10-20 and 1.20 10-18 m2, depending on the nature of the percolating volume. The influence of the nanoscale porosity on the mesoscopic permeability is also studied. Two examples show that despite the scale ratio between the mesoscopic and nanoscopic pores, the nanoscopic pore structure cannot be neglected to estimate the permeability of the pore clay matrix. Finally, the sample provided by micro-CT is considered as a porous medium composed of three phases with permeabilities 0 (for the non porous minerals), 1 (for the porous clay matrix) and infinity (for the macroscopic pores). The overall permeability Kmacro is obtained by solving the Darcy's equation with a variable local permeability with spatially periodic boundary conditions. Kmacro is found of the order of 0.4 and the medium is relatively isotropic on this scale. This estimation of Kmacro is in agreement with the measured value.

The Evolution of Cracks in Maluanshan Granite Subjected to Different Temperature Processing

NASA Astrophysics Data System (ADS)

Jiang, Guanghui; Zuo, Jianping; Li, Liyun; Ma, Teng; Wei, Xu

2018-06-01

The understanding of the change in the physical and mechanical properties of rock before and after heating is of great significance for the site selection of mattamore and the exploitation of geothermal resources. It is known that before and after heating, the changes in wave velocity, wave velocity anisotropy and permeability of rock are due to the evolution of cracks in the rock. In this study, the wave velocity and permeability of granite specimen from the Maluanshan tunnel in Shenzhen, China, were measured after high-temperature processing at atmospheric pressure. The effects of temperature on the properties of rock based on the acoustics and permeability were measured and analyzed. The evolution of the cracks in Maluanshan granite was inverted through the change rule of the cracks, wave velocity anisotropy and permeability with temperature. The main conclusions were as follows: (1) Both granite P and S wave velocities decreased with the increasing temperature, and the thermal cracking occurred in four stages: between 50 and 250 °C, the crack stabilization development stage was in effect; between 250 and 300 °C, an accelerated development stage of the cracks existed; between 300 and 350 °C, a shift stage for the cracks was entered; and finally, from 350 to 700 °C, the cracks continued into a further development stage; (2) The coefficient of variation could be used to reflect the structural feature change of the rocks in the study of the wave velocity anisotropy. The structures of cracks were observed to change before and after 300 °C. (3) The Maluanshan granite permeability increases with the increasing processing temperature. It was observed that the higher the processing temperature, the larger the increase in the permeability rate. A porosity function was used as a variable to analyze the relationship between the porosity function and permeability as follows: from 50 to 200 °C, the permeability was determined by the microcracks; 200-400 °C was the transition stage; and between 400 and 700 °C, the permeability was determined by the macrocracks.

Finite Element Modeling of Transient Head Field Associated with Partially Penetrating, Slug Tests in a Heterogeneous Aquifer with Low Permeability, Stratigraphic Zones and Faults

NASA Astrophysics Data System (ADS)

Cheng, J.; Johnson, B.; Everett, M.

2003-12-01

Preliminary field work shows slug interference tests using an array of multilevel active and monitoring wells have potential of permitting enhanced aquifer characterization. Analysis of these test data, however, ultimately will rely on numerical geophysical inverse models. In order to gain insight as well as to provide synthetic data sets, we use a 3-D finite element analysis (code:FEHM-LANL) to explore the effect of idealized, low permeability, stratigraphical and structural (faults) heterogeneities on the transient head field associated with a slug test in a packer-isolated interval of an open borehole. The borehole and packers are modeled explicitly; wellbore storage is selected to match values of field tests. The homogeneous model exhibits excellent agreement with that of the semi-analytical model of Liu and Butler (1995). Models are axisymmetric with a centrally located slugged interval within a homogenous, isotropic, confined aquifer with embedded, horizontal or vertical zones of lower permeability that represent low permeability strata or faults, respectively. Either one or two horizontal layers are located opposite the borehole packers, which is a common situation at the field site; layer thickness (0.15-0.75 m), permeability contrast (up to 4 orders of magnitude contrast) and lateral continuity of layers are varied between models. The effect of a "hole" in a layer also is assessed. Fault models explore effects of thickness (0.05-0.75 m) and permeability contrast as well as additional effects associated with the offset of low permeability strata. Results of models are represented most clearly by contour maps of time of arrival and normalized amplitude of peak head perturbation, but transient head histories at selected locations provide additional insight. Synthesis of the models is on-going but a few points can be made at present. Spatial patterns are distinctive and allow easy discrimination between stratigraphic and structural impedance features. Time delays and amplitude reduction increase nonlinearly with increasing permeability contrast. The capacity to discriminate the effect of layer thickness decreases as permeability contrast increases.

Analysis and application of classification methods of complex carbonate reservoirs

NASA Astrophysics Data System (ADS)

Li, Xiongyan; Qin, Ruibao; Ping, Haitao; Wei, Dan; Liu, Xiaomei

2018-06-01

There are abundant carbonate reservoirs from the Cenozoic to Mesozoic era in the Middle East. Due to variation in sedimentary environment and diagenetic process of carbonate reservoirs, several porosity types coexist in carbonate reservoirs. As a result, because of the complex lithologies and pore types as well as the impact of microfractures, the pore structure is very complicated. Therefore, it is difficult to accurately calculate the reservoir parameters. In order to accurately evaluate carbonate reservoirs, based on the pore structure evaluation of carbonate reservoirs, the classification methods of carbonate reservoirs are analyzed based on capillary pressure curves and flow units. Based on the capillary pressure curves, although the carbonate reservoirs can be classified, the relationship between porosity and permeability after classification is not ideal. On the basis of the flow units, the high-precision functional relationship between porosity and permeability after classification can be established. Therefore, the carbonate reservoirs can be quantitatively evaluated based on the classification of flow units. In the dolomite reservoirs, the average absolute error of calculated permeability decreases from 15.13 to 7.44 mD. Similarly, the average absolute error of calculated permeability of limestone reservoirs is reduced from 20.33 to 7.37 mD. Only by accurately characterizing pore structures and classifying reservoir types, reservoir parameters could be calculated accurately. Therefore, characterizing pore structures and classifying reservoir types are very important to accurate evaluation of complex carbonate reservoirs in the Middle East.

OOMMPPAA: A Tool To Aid Directed Synthesis by the Combined Analysis of Activity and Structural Data

PubMed Central

2014-01-01

There is an ever increasing resource in terms of both structural information and activity data for many protein targets. In this paper we describe OOMMPPAA, a novel computational tool designed to inform compound design by combining such data. OOMMPPAA uses 3D matched molecular pairs to generate 3D ligand conformations. It then identifies pharmacophoric transformations between pairs of compounds and associates them with their relevant activity changes. OOMMPPAA presents this data in an interactive application providing the user with a visual summary of important interaction regions in the context of the binding site. We present validation of the tool using openly available data for CDK2 and a GlaxoSmithKline data set for a SAM-dependent methyl-transferase. We demonstrate OOMMPPAA’s application in optimizing both potency and cell permeability and use OOMMPPAA to highlight nuanced and cross-series SAR. OOMMPPAA is freely available to download at http://oommppaa.sgc.ox.ac.uk/OOMMPPAA/. PMID:25244105

HIGH PERMEABILITY MEMBRANES FOR THE DEHYDRATION OF LOW WATER CONTENT ETHANOL BY PERVAPORATION

EPA Science Inventory

Energy efficient dehydration of low water content ethanol is a challenge for the sustainable production of fuel-grade ethanol. Pervaporative membrane dehydration using a recently developed hydrophilic polymer membrane formulation consisting of a cross-linked mixture of poly(allyl...

Ionic cross-linked polyether and silica gel mixed matrix membranes for CO 2 separation from flue gas

DOE PAGES

Sekizkardes, Ali K.; Zhou, Xu; Nulwala, Hunaid B.; ...

2017-09-22

Mixed matrix membranes (MMMs) were prepared by incorporating 10 wt%, 20 wt% and 30 wt% silica gel filler particles into novel ionic cross-linked polyether (IXPE) polymers. Porous silica gel has the advantage of high surface area that can increase the free volume and permeability in a polymer film while also being commercially available and low cost. The MMMs featured high chemical and thermal stability as well as a modest improvement in storage modulus. These features are due to the excellent interfacial interaction between silica gel filler particles and the polymer matrix. Increasing the loading of silica gel particles in MMMsmore » resulted in higher permeability up to 120 Barrer for CO 2, which is about 40% higher than the neat polymer matrix. Finally, most importantly, the MMMs maintained a very high CO 2/N 2 selectivity performance of around 41 for all particle loadings that were tested.« less

Polymeric molecular sieve membranes via in situ cross-linking of non-porous polymer membrane templates.

PubMed

Qiao, Zhen-An; Chai, Song-Hai; Nelson, Kimberly; Bi, Zhonghe; Chen, Jihua; Mahurin, Shannon M; Zhu, Xiang; Dai, Sheng

2014-04-16

High-performance polymeric membranes for gas separation are attractive for molecular-level separations in industrial-scale chemical, energy and environmental processes. Molecular sieving materials are widely regarded as the next-generation membranes to simultaneously achieve high permeability and selectivity. However, most polymeric molecular sieve membranes are based on a few solution-processable polymers such as polymers of intrinsic microporosity. Here we report an in situ cross-linking strategy for the preparation of polymeric molecular sieve membranes with hierarchical and tailorable porosity. These membranes demonstrate exceptional performance as molecular sieves with high gas permeabilities and selectivities for smaller gas molecules, such as carbon dioxide and oxygen, over larger molecules such as nitrogen. Hence, these membranes have potential for large-scale gas separations of commercial and environmental relevance. Moreover, this strategy could provide a possible alternative to 'classical' methods for the preparation of porous membranes and, in some cases, the only viable synthetic route towards certain membranes.

Measuring accessibility of sustainable transportation using space syntax in Bojonggede area

NASA Astrophysics Data System (ADS)

Suryawinata, B. A.; Mariana, Y.; Wijaksono, S.

2017-12-01

Changes in the physical structure of regional space as a result of the increase of planned and unplanned settlements in the Bojonggede area have an impact on the road network pattern system. Changes in road network patterns will have an impact on the permeability of the area. Permeability measures the extent to which road network patterns provide an option in traveling. If the permeability increases the travel distance decreases and the route of travel choice increases, permeability like this can create an easy access system and physically integrated. This study aims to identify the relationship of physical characteristics of residential area and road network pattern to the level of space permeability in Bojonggede area. By conducting this research can be a reference for the arrangement of circulation, accessibility, and land use in the vicinity of Bojonggede. This research uses quantitative method and space syntax method to see global integration and local integration on the region which become the parameter of permeability level. The results showed that the level of permeability globally and locally high in Bojonggede physical area is the physical characteristics of the area that has a grid pattern of road network grid.

Morphological Characterization of Silicone Hydrogels

NASA Astrophysics Data System (ADS)

Gido, Samuel

2007-03-01

Silicone hydrogel materials are used in the latest generation of extended wear soft contact lenses. To ensure comfort and eye health, these materials must simultaneously exhibit high oxygen permeability and high water permeability / hydrophilicity. The materials achieve these opposing requirements based on bicontinuous composite of nanoscale domains of oxygen permeable (silicones) and hydrophilic (water soluble polymer) materials. The microphase separated morphology of silicone hydrogel contact lens materials was imaged using field emission gun scanning transmission electron microscopy (FEGSTEM), and atomic force microscopy (AFM). Additional morphological information was provided by small angle X-ray scattering (SAXS). These results all indicate a nanophase separated structure of silicone rich (oxygen permeable) and carbon rich (water soluble polymer) domains separated on a length scale of about 10 nm.

Three-dimensional geologic model of the southeastern Espanola Basin, Santa Fe County, New Mexico

USGS Publications Warehouse

Pantea, Michael P.; Hudson, Mark R.; Grauch, V.J.S.; Minor, Scott A.

2011-01-01

This multimedia model and report show and describe digital three-dimensional faulted surfaces and volumes of lithologic units that confine and constrain the basin-fill aquifers within the Espanola Basin of north-central New Mexico. These aquifers are the primary groundwater resource for the cities of Santa Fe and Espanola, six Pueblo nations, and the surrounding areas. The model presented in this report is a synthesis of geologic information that includes (1) aeromagnetic and gravity data and seismic cross sections; (2) lithologic descriptions, interpretations, and geophysical logs from selected drill holes; (3) geologic maps, geologic cross sections, and interpretations; and (4) mapped faults and interpreted faults from geophysical data. Modeled faults individually or collectively affect the continuity of the rocks that contain the basin aquifers; they also help define the form of this rift basin. Structure, trend, and dip data not previously published were added; these structures are derived from interpretations of geophysical information and recent field observations. Where possible, data were compared and validated and reflect the complex relations of structures in this part of the Rio Grande rift. This interactive geologic framework model can be used as a tool to visually explore and study geologic structures within the Espanola Basin, to show the connectivity of geologic units of high and low permeability between and across faults, and to show approximate dips of the lithologic units. The viewing software can be used to display other data and information, such as drill-hole data, within this geologic framework model in three-dimensional space.

Activated carbon fiber composite material and method of making

DOEpatents

Burchell, Timothy D.; Weaver, Charles E.; Chilcoat, Bill R.; Derbyshire, Frank; Jagtoyen, Marit

2000-01-01

An activated carbon fiber composite for separation and purification, or catalytic processing of fluids is described. The activated composite comprises carbon fibers rigidly bonded to form an open, permeable, rigid monolith capable of being formed to near-net-shape. Separation and purification of gases are effected by means of a controlled pore structure that is developed in the carbon fibers contained in the composite. The open, permeable structure allows the free flow of gases through the monolith accompanied by high rates of adsorption. By modification of the pore structure and bulk density the composite can be rendered suitable for applications such as gas storage, catalysis, and liquid phase processing.

Activated carbon fiber composite material and method of making

DOEpatents

Burchell, Timothy D.; Weaver, Charles E.; Chilcoat, Bill R.; Derbyshire, Frank; Jagtoyen, Marit

2001-01-01

An activated carbon fiber composite for separation and purification, or catalytic processing of fluids is described. The activated composite comprises carbon fibers rigidly bonded to form an open, permeable, rigid monolith capable of being formed to near-net-shape. Separation and purification of gases are effected by means of a controlled pore structure that is developed in the carbon fibers contained in the composite. The open, permeable structure allows the free flow of gases through the monolith accompanied by high rates of adsorption. By modification of the pore structure and bulk density the composite can be rendered suitable for applications such as gas storage, catalysis, and liquid phase processing.

Impacts of relative permeability on CO2 phase behavior, phase distribution, and trapping mechanisms

NASA Astrophysics Data System (ADS)

Moodie, N.; McPherson, B. J. O. L.; Pan, F.

2015-12-01

A critical aspect of geologic carbon storage, a carbon-emissions reduction method under extensive review and testing, is effective multiphase CO2 flow and transport simulation. Relative permeability is a flow parameter particularly critical for accurate forecasting of multiphase behavior of CO2 in the subsurface. The relative per­meability relationship assumed and especially the irreducible saturation of the gas phase greatly impacts predicted CO2 trapping mechanisms and long-term plume migration behavior. A primary goal of this study was to evaluate the impact of relative permeability on efficacy of regional-scale CO2 sequestration models. To accomplish this we built a 2-D vertical cross-section of the San Rafael Swell area of East-central Utah. This model simulated injection of CO2 into a brine aquifer for 30 years. The well was then shut-in and the CO2 plume behavior monitored for another 970 years. We evaluated five different relative permeability relationships to quantify their relative impacts on forecasted flow results of the model, with all other parameters maintained uniform and constant. Results of this analysis suggest that CO2 plume movement and behavior are significantly dependent on the specific relative permeability formulation assigned, including the assumed irreducible saturation values of CO2 and brine. More specifically, different relative permea­bility relationships translate to significant differences in CO2 plume behavior and corresponding trapping mechanisms.

Permeability of rhynchophylline across human intestinal cell in vitro

PubMed Central

Ma, Bo; Wang, Jing; Sun, Jing; Li, Ming; Xu, Huibo; Sun, Guibo; Sun, Xiaobo

2014-01-01

Rhynchophylline (Rhy) is the major component of Uncaria species, which is used in Chinese traditional medicine for the treatment of central nervous system disorders. However, its oral bioavailability has not been known. This study aims to investigate the intestinal permeability and related mechanisms of Rhy using cultured human epithelial Caco-2 cells. The cytotoxicity of Rhy on Caco-2 cells was evaluated with MTT assay. The effect of Rhy on the integrity of Caco-2 cell monolayer was assayed with transepithelial electrical resistance. The permeability of Rhy across cell monolayer was assayed by measuring Rhy quantity in received side with HPLC. The effect of Rhy on the expression of P-glycoprotein and MDR1 was detected with Western blot and flow cytometry, respectively. In the concentration of Rhy, which did not produce toxicity on cell viability and integrity of Caco-2 cell monolayer, Rhy crossed the monolayer with velocity 2.76~5.57×10^-6 cm/sec and 10.68~15.66×10^-6 cm/sec from apical to basolateral side and from basolateral to apical side, respectively. The permeability of Rhy was increased by verapamil, a P-glycoprotein inhibitor, or rhodamine123, a P-glycoprotein substrate. Rhy revealed an induction effect on P-glycoprotein expression in Caco-2 cells. These results demonstrate the low permeability of Rhy in intro, and suggest that P-glycoprotein may underlie the mechanism. PMID:24966905

The specific features of gold ore provinces of the south of Siberia in a magnetic field at ground height and heights of flight of satellite Champ.

NASA Astrophysics Data System (ADS)

Litvinova, Tamara; Petrova, Alevtina

2010-05-01

The specific features of gold ore provinces of the south of Siberia in a magnetic field at ground height and heights of flight of satellite Champ. T.Litvinova -All-Russian Geological Research Institute (VSEGEI) A. Petrova - St. Petersburg, SPbF IZMIRAN, Russian Academy of Sciences, St. Petersburg For allocation of specific features known gold ore objects (Olimpiadninskoje, Suchoi Log, etc.) is executed the morphological analysis of the magnetic field received on materials of aeromagnetic data and satellite measurements at heights of 100 and 400 km. On the ground data on a map of magnetic anomalies of Russia of scale 1:2 500000 of 50 km on the extended structures crossing known gold ore deposits and promising ore units have been constructed geomagnetic and densitys sections up to depth. On geomagnetic and densitys sections to known large gold ore to deposits are dated deep synvertical the permeable zones described by a synlenticular -layered structure. Extended horizons of not magnetic formations are located on depths about 10, 12, 15-18, 30 and 40 km. On deep densitys sections reference sites ¬ the Suchoi Log, Olimpiadninskoje and Vodorazdelnoje ¬ is characterized by zones of inversion of density. Areas of the loosened breeds are dated to synvertical to deep zones of hydrothermal and fluid study of breeds inside which the loosened lenses in intervals of depths from 2 up to 5 km are formed, 8-13 km, 18-20 and 25-30 km of 35-40 km within the limits of the bottom bark. The analysis of a magnetic field has shown, that gold mineralization in researched region is dated for zones of long-living regional explosive infringements, to permeable terrigenous to thicknesses of depressions, to adjournment depression structures in units of crossing of tectonofluid zones of diagonal orientation. Terrigenous adjournment depression structures are shown on a geomagnetic section as the powerful deflections filled with low-magnetic thicknesses. These deflections are dated to synvertical to deep zones of low-magnetic breeds, probably, reflecting influence of the high-temperature tectonofluid processes occuring on the big depths (up to 30 - 35 km), and explosive infringements shown through systems. It testifies to presence of a long-living deep zone of differentiation of substance when inside the base lenses of the loosened breeds are formed, and more dense breeds mapping in near-surface formations. It was represented interesting to track as the laws allocated on the ground aeromagnetic data are reflected in satellite anomalies. The analysis has shown, that gold ore areas Barguzino - Vitim evgeosynclinal zones gravitate to a local minimum of a magnetic field of satellite Champ at height of 100 km. Zones of minima at height of 100 km coincide with position of permeable blocks of the earth's crust allocated on extended structures, executed by results of ground shooting. The considered zones of minima at height of 400 km practically do not change the morphology. Local steady minima in area Barguzino - Vitim zones on maps of satellite Champ can be connected with heattd-up long-living fluidized the channels providing gold ore and rare-metal a mineralization of the region.

Scale effect and value criterion of the permeability of the interlayer staggered zones in the basalt of Jinsha River basin, China

NASA Astrophysics Data System (ADS)

Zhou, Zhifang; Lin, Mu; Guo, Qiaona; Chen, Meng

2018-05-01

The hydrogeological characteristics of structural planes are different to those of the associated bedrock. The permeability, and therefore hydraulic conductivity (K), of a structural plane can be significantly different at different scales. The interlayer staggered zones in the Emeishan Basalt of early Late Permian were studied; this formation is located in the Baihetan hydropower project area in Jinsha River Basin, China. The seepage flow distribution of a solid model and two generalized models (A and B) were computed using COMSOL. The K values of the interlayer staggered zones for all three models were calculated by both simulation and analytical methods. The results show that the calculated K results of the generalized models can reflect the variation trend of permeability in each section of the solid model, and the approximate analytical calculation of K can be taken into account in the calculation of K in the generalized models instead of that found by simulation. Further studies are needed to investigate permeability variation in the interlayer staggered zones under the condition of different scales, considering the scaling variation in each section of an interlayer staggered zone. The permeability of each section of an interlayer staggered zone presents a certain degree of dispersivity at small scales; however, the permeability values tends to converge to a similar value as the scale of each section increases. The regularity of each section of the interlayer staggered zones under the condition of different scales can provide a scientific basis for reasonable selection of different engineering options.

Water and solute permeability of rat lung caveolae: high permeabilities explained by acyl chain unsaturation.

PubMed

Hill, Warren G; Almasri, Eyad; Ruiz, W Giovanni; Apodaca, Gerard; Zeidel, Mark L

2005-07-01

Caveolae are invaginated membrane structures with high levels of cholesterol, sphingomyelin, and caveolin protein that are predicted to exist as liquid-ordered domains with low water permeability. We isolated a caveolae-enriched membrane fraction without detergents from rat lung and characterized its permeability properties to nonelectrolytes and protons. Membrane permeability to water was 2.85 +/- 0.41 x 10(-3) cm/s, a value 5-10 times higher than expected based on comparisons with other cholesterol and sphingolipid-enriched membranes. Permeabilities to urea, ammonia, and protons were measured and found to be moderately high for urea and ammonia at 8.85 +/- 2.40 x 10(-7)and 6.84 +/- 1.03 x 10(-2) respectively and high for protons at 8.84 +/- 3.06 x 10(-2) cm/s. To examine whether caveolin or other integral membrane proteins were responsible for high permeabilities, liposomes designed to mimic the lipids of the inner and outer leaflets of the caveolar membrane were made. Osmotic water permeability to both liposome compositions were determined and a combined inner/outer leaflet water permeability was calculated and found to be close to that of native caveolae at 1.58 +/- 1.1 x 10(-3) cm/s. In caveolae, activation energy for water flux was high (19.4 kcal/mol) and water permeability was not inhibited by HgCl2; however, aquaporin 1 was detectable by immunoblotting. Immunostaining of rat lung with AQP1 and caveolin antisera revealed very low levels of colocalization. We conclude that aquaporin water channels do not contribute significantly to the observed water flux and that caveolae have relatively high water and solute permeabilities due to the high degree of unsaturation in their fatty acyl chains.

Preparation and characterization of free films of high amylose/pectin mixtures cross-linked with sodium trimetaphosphate.

PubMed

Prezotti, Fabíola Garavello; Meneguin, Andréia Bagliotti; Evangelista, Raul Cesar; Cury, Beatriz Stringhetti Ferreira

2012-11-01

High amylose and pectin were mixed at 1:1 mass ratio and cross-linked with sodium trimetaphosphate (STMP) in alkaline medium. Films were prepared from aqueous dispersions of these cross-linked polymer blend at three different concentrations (3, 4 and 5%), by solvent casting method. Characterization of the films included thickness, surface morphology, water uptake, water vapor permeability (WVP), tensile strength measurements and enzymatic digestion. The cross-linking allowed to obtain films with improved mechanical properties and reduced WVP. The high resistance to enzymatic digestion exhibited by these films represents a promising approach to their application in the development of colon drug delivery systems.

Analytical approximations for effective relative permeability in the capillary limit

NASA Astrophysics Data System (ADS)

Rabinovich, Avinoam; Li, Boxiao; Durlofsky, Louis J.

2016-10-01

We present an analytical method for calculating two-phase effective relative permeability, krjeff, where j designates phase (here CO2 and water), under steady state and capillary-limit assumptions. These effective relative permeabilities may be applied in experimental settings and for upscaling in the context of numerical flow simulations, e.g., for CO2 storage. An exact solution for effective absolute permeability, keff, in two-dimensional log-normally distributed isotropic permeability (k) fields is the geometric mean. We show that this does not hold for krjeff since log normality is not maintained in the capillary-limit phase permeability field (Kj=k·krj) when capillary pressure, and thus the saturation field, is varied. Nevertheless, the geometric mean is still shown to be suitable for approximating krjeff when the variance of ln⁡k is low. For high-variance cases, we apply a correction to the geometric average gas effective relative permeability using a Winsorized mean, which neglects large and small Kj values symmetrically. The analytical method is extended to anisotropically correlated log-normal permeability fields using power law averaging. In these cases, the Winsorized mean treatment is applied to the gas curves for cases described by negative power law exponents (flow across incomplete layers). The accuracy of our analytical expressions for krjeff is demonstrated through extensive numerical tests, using low-variance and high-variance permeability realizations with a range of correlation structures. We also present integral expressions for geometric-mean and power law average krjeff for the systems considered, which enable derivation of closed-form series solutions for krjeff without generating permeability realizations.

Mixed Gas Hydrogen Sulfide Permeability and Separation Using Supported Polyphosphazene Membranes

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

Frederick F. Stewart; Christopher J. Orme

Three phosphazene polymers were characterized for permeability using a suite of pure gases, including H2S where high permeabilities were measured with respect to the other gases in the study. Furthermore, mixed gas selectivities were determined and compared to the ideal gas selectivities for the H2S/CH4, CO2/CH4, and Ar/CH4 gas pairs. The three phosphazenes represent a set of membrane materials differing by their polarities. Description of the polarity of each was performed using Hansen solubility parameters derived from group contributions for each chemical structure. A good correlation was observed between the polar Hansen parameter (äp) and the gas permeabilities of bothmore » CO2 and H2S. Furthermore, permeant gas critical temperatures were also found to correlate with permeability suggesting a solubility driven transport process. A comparison of the mixed gas permeabilities with the corresponding pure gas data revealed good agreement in the data, although the presence of more condensable gases hinders non-polar gas transport resulting in higher separation factors.« less

Aging properties of films of plasticized vital wheat gluten cast from acidic and basic solutions.

PubMed

Olabarrieta, Idoia; Cho, Sung-Woo; Gällstedt, Mikael; Sarasua, Jose-Ramon; Johansson, Eva; Hedenqvist, Mikael S

2006-05-01

In order to understand the mechanisms behind the undesired aging of films based on vital wheat gluten plasticized with glycerol, films cast from water/ethanol solutions were investigated. The effect of pH was studied by casting from solutions at pH 4 and pH 11. The films were aged for 120 days at 50% relative humidity and 23 degrees C, and the tensile properties and oxygen and water vapor permeabilities were measured as a function of aging time. The changes in the protein structure were determined by infrared spectroscopy and size-exclusion and reverse-phase high-performance liquid chromatography, and the film structure was revealed by optical and scanning electron microscopy. The pH 11 film was mechanically more stable with time than the pH 4 film, the latter being initially very ductile but turning brittle toward the end of the aging period. The protein solubility and infrared spectroscopy measurements indicated that the protein structure of the pH 4 film was initially significantly less polymerized/aggregated than that of the pH 11 film. The polymerization of the pH 4 film increased during storage but it did not reach the degree of aggregation of the pH 11 film. Reverse-phase chromatography indicated that the pH 11 films were to some extent deamidated and that this increased with aging. At the same time a large fraction of the aged pH 11 film was unaffected by reducing agents, suggesting that a time-induced isopeptide cross-linking had occurred. This isopeptide formation did not, however, change the overall degree of aggregation and consequently the mechanical properties of the film. During aging, the pH 4 films lost more mass than the pH 11 films mainly due to migration of glycerol but also due to some loss of volatile mass. Scanning electron and optical microscopy showed that the pH 11 film was more uniform in thickness and that the film structure was more homogeneous than that of the pH 4 film. The oxygen permeability was also lower for the pH 11 film. The fact that the pH 4 film experienced a larger and more rapid change in its mechanical properties with time than the pH 11 film, as a consequence of a greater loss of plasticizer, was presumably due to its initial lower degree of protein aggregation/polymerization. Consequently, the cross-link density achieved at pH 4 was too low to effectively retain volatiles and glycerol within the matrix.

The permeability of fault zones in the upper continental crust: statistical analysis from 460 datasets, updated depth-trends, and permeability contrasts between fault damage zones and protoliths.

NASA Astrophysics Data System (ADS)

Scibek, J.; Gleeson, T. P.; Ingebritsen, S.; McKenzie, J. M.

2017-12-01

Fault zones are an important part of the hydraulic structure of the Earth's crust and influence a wide range of Earth processes and a large amount of test data has been collected over the years. We conducted a meta-analysis of global of fault zone permeabilities in the upper brittle continental crust, using about 10,000 published research items from a variety of geoscience and engineering disciplines. Using 460 datasets at 340 localities, the in-situ bulk permeabilities (>10's meters scale, including macro-fractures) and matrix permeabilities (drilled core samples or outcrop spot tests) are separated, analyzed, and compared. The values have log-normal distributions and we analyze the log-permeability values. In the fault damage zones of plutonic and metamorphic rocks the mean bulk permeability was 1x10-14m2, compared to matrix mean of 1x10-16m2. In sedimentary siliciclastic rocks the mean value was the same for bulk and matrix permeability (4x10-14m2). More useful insights were determined from the regression analysis of paired permeability data at all sites (fault damage zone vs. protolith). Much of the variation in fault permeability is explained by the permeability of protolith: in relatively weak volcaniclastic and clay-rich rocks up to 70 to 88% of the variation is explained, and only 20-30% in plutonic and metamorphic rocks. We propose a revision at shallow depths for previously published upper-bound curves for the "fault-damaged crust " and the geothermal-metamorphic rock assemblage outside of major fault zones. Although the bounding curves describe the "fault-damaged crust" permeability parameter space adequately, the only statistically significant permeability-depth trend is for plutonic and metamorphic rocks (50% of variation explained). We find a depth-dependent systematic variation of the permeability ratio (fault damage zone / protolith) from the in-situ bulk permeability global data. A moving average of the log-permeability ratio value is 2 to 2.5 (global mean is 2.2). Although the data is unevenly distributed with depth, the present evidence is that the permeability ratio is at a maximum at depths 1 to 2 kilometers, decreases with depth below 2km, and is also lower near the ground surface.

The Application of Fractal and Multifractal Theory in Hydraulic-Flow-Unit Characterization and Permeability Estimation

NASA Astrophysics Data System (ADS)

Chen, X.; Yao, G.; Cai, J.

2017-12-01

Pore structure characteristics are important factors in influencing the fluid transport behavior of porous media, such as pore-throat ratio, pore connectivity and size distribution, moreover, wettability. To accurately characterize the diversity of pore structure among HFUs, five samples selected from different HFUs (porosities are approximately equal, however permeability varies widely) were chosen to conduct micro-computerized tomography test to acquire direct 3D images of pore geometries and to perform mercury injection experiments to obtain the pore volume-radii distribution. To characterize complex and high nonlinear pore structure of all samples, three classic fractal geometry models were applied. Results showed that each HFU has similar box-counting fractal dimension and generalized fractal dimension in the number-area model, but there are significant differences in multifractal spectrums. In the radius-volume model, there are three obvious linear segments, corresponding to three fractal dimension values, and the middle one is proved as the actual fractal dimension according to the maximum radius. In the number-radius model, the spherical-pore size distribution extracted by maximum ball algorithm exist a decrease in the number of small pores compared with the fractal power rate rather than the traditional linear law. Among the three models, only multifractal analysis can classify the HFUs accurately. Additionally, due to the tightness and low-permeability in reservoir rocks, connate water film existing in the inner surface of pore channels commonly forms bound water. The conventional model which is known as Yu-Cheng's model has been proved to be typically not applicable. Considering the effect of irreducible water saturation, an improved fractal permeability model was also deduced theoretically. The comparison results showed that the improved model can be applied to calculate permeability directly and accurately in such unconventional rocks.

Beach Resilience to Coastal Structures on a Natural Beach

NASA Astrophysics Data System (ADS)

Torres-Freyermuth, A.; Medellín, G.; Hofman, A.; Tereszkiewicz, P.; Palemón-Arcos, L.; López-González, J.

2016-12-01

Beach resilience plays an important role on reducing coastal risk associated to either natural or human induced perturbations affecting the coast. Field experiments were conducted in order to investigate beach resilience in Sisal, Yucatán. Both impermeable and permeable 14-m groins were designed to asses the impact of coastal structures on the beach morphology during a 24-hour period. The experiments were conducted in the spring of 2015 and 2016, allowing the assessment of both structures under similar forcing conditions. Intense sea breeze events (W>12 m/s) generated high-angle short-waves, driving alongshore transport in the swash zone. Wind, waves, tides, and currents were measured concurrently and are correlated with beach morphology evolution data derived from intense monitoring conducted during the structure deployment. The impermeable structure induced a significant beach accretion (>60 m3/day) in the updrift side of the structure causing a tremendous impact downdrift. On the other hand, the permeable groin induced a smaller but still significant accretion (40 m3/day), allowing sediment bypass throughout the structure. Furthermore, the beach surveying continued after structures removal in order to estimate the beach recovery capability. Field observations show that the impact of the structure on the morphology is negligible six days after structure removal for the impermeable groin and only one day for the permeable structure. The latter suggests the high beach resilience of the study area. We acknowledge field support provided by researchers and students at the LIPC-UNAM. Financial support was provided by CONACYT (Projects LN271544 and Cátedras 1146), DGAPA-UNAM (PAPIIT-IN107315) and Grupo BARI.

Pore-Scale Simulation and Sensitivity Analysis of Apparent Gas Permeability in Shale Matrix

PubMed Central

Zhang, Pengwei; Hu, Liming; Meegoda, Jay N.

2017-01-01

Extremely low permeability due to nano-scale pores is a distinctive feature of gas transport in a shale matrix. The permeability of shale depends on pore pressure, porosity, pore throat size and gas type. The pore 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 pore network model that includes typical bimodal pore size distribution, anisotropy and low connectivity of the pore structure in shale. The apparent gas permeability of shale matrix was calculated under different reservoir pressures corresponding to different gas exploitation stages. Results indicate that gas permeability is strongly related to reservoir gas pressure, 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 pressures 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 pore throat size and porosity. Finally, the impact of connectivity of nano-scale pores 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

Pore-Scale Simulation and Sensitivity Analysis of Apparent Gas Permeability in Shale Matrix.

PubMed

Zhang, Pengwei; Hu, Liming; Meegoda, Jay N

2017-01-25

Extremely low permeability due to nano-scale pores is a distinctive feature of gas transport in a shale matrix. The permeability of shale depends on pore pressure, porosity, pore throat size and gas type. The pore 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 pore network model that includes typical bimodal pore size distribution, anisotropy and low connectivity of the pore structure in shale. The apparent gas permeability of shale matrix was calculated under different reservoir pressures corresponding to different gas exploitation stages. Results indicate that gas permeability is strongly related to reservoir gas pressure, 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 pressures 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 pore throat size and porosity. Finally, the impact of connectivity of nano-scale pores 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.

Development and Differentiation of Mesenchymal Bone Marrow Cells in Porous Permeable Titanium Nickelide Implants In Vitro and In Vivo.

PubMed

Kokorev, O V; Khodorenko, V N; Radkevich, A A; Dambaev, G Ts; Gunter, V E

2016-08-01

We studied the structure of porous permeable titanium nickelide used as the scaffold. In vitro population of the porous scaffold with multipotent mesenchymal stem bone marrow cells on days 7, 14, 21, and 28 was analyzed by scanning electron microscopy. Stage-by-stage histogenesis of the tissues formed from the bone marrow cells in the titanium nickelide scaffold in vivo is described in detail. Using mesenchymal stem cells, we demonstrated that porous permeable titanium nickelide scaffolds are unique incubators for cell cultures applicable for tissue engineering.

The use of subsurface thermal data, isotopic tracers and earthquake hypocenter locations to unravel deep regional flow systems within the crystalline basement beneath the Rio Grande rift, New Mexico. (Invited)

NASA Astrophysics Data System (ADS)

Person, M. A.; Woolsey, E.; Pepin, J.; Crossey, L. J.; Karlstrom, K. E.; Phillips, F. M.; Kelley, S.; Timmons, S.

2013-12-01

The Rio Grande rift in New Mexico hosts a number of low-temperature geothermal systems as well as the 19 km deep Socorro Magma Body. The presence of a mantle helium anomaly measured at San Acacia spring (3He/4He = 0.295 RA) and in an adjacent shallow well (50m < ; 0.8 RA) overlying the Socorro Magma Body at the southern terminus of the Albuquerque Basin suggests that deeply sourced fluids mix with the sedimentary basin groundwater flow system. Temperatures recorded at the base of the San Acacia well is elevated (29 oC). Published estimates of uplift rates and heat flow suggest that the magma body was emplaced about 1-3 ka and reflects a long-lived (several Ma) magmatic system. Further south near the southern terminus of the Engle Basin, much warmer temperatures (42 oC) occur at shallow depths within the spa district in the town of Truth or Consequences at shallow depths also suggesting deep-fluid circulation. 14C constrained apparent groundwater residence times in the spa district range between 6-10 ka. We have developed two 6-19 km deep crustal-scale, cross-sectional models that simulate subsurface fluid flow, heat and isotope (3He/4He) transport as well as groundwater residence times along the Rio Grande rift. The North-South oriented model of the Albuquerque Basin incorporates a high-permeability conduit 100 m wide having hydrologic properties differing from surrounding crystalline basement units. We use these models to constrain the crustal permeability structure and fluid circulation patterns beneath the Albuquerque and Engle Basins. Model results are compared to measurements of groundwater temperatures, residence times (14C), and 3He/4He data. We also use the distribution of earthquake hypocenters to constrain likely fault-crystalline basement hydraulic interactions in the seismogenic crust above the Socorro Magma Body. For the case of the southern Albuquerque Basin, conduit permeability associated with the Indian Hill conduit/fault zone must range between about 1.0E-13 to 1.0E-15 m2 in order for simulated 3He/4He, solute concentrations, and temperatures to match observed conditions. Basement permeability outside of the fault damage zone must range between 1.0E-17 to 1.0E-18 m2. However, a much longer transport time is required (between about 20-30 ka) in order to match observed conditions suggesting multiple magmatic intrusion events. For the case of the Engle Basin near Truth or Consequences, bulk crustal permeability between a depth of 2-6 km below the sedimentary succession must approach 1.0E-12 m2 in order to reproduce hot spring temperatures and groundwater residence times. We compare these model derived permeability estimates to published permeability-depth relationships for crustal rocks (Manning and Ingebritsen, 1999; Ingebritsen and Manning, 2010).

Evaluating potential effects of widening US 64 on red wolves in Washington, Tyrrell, and Dare Counties, North Carolina.

DOT National Transportation Integrated Search

2011-12-31

We used data from 16 red wolves fitted with GPS-collars between January 2009 and April 2011 to evaluate home range size and : habitat selection, road permeability, and identify significant red wolf highway crossing locations. Home range size for red ...

Alaskan Fish Gelatin Films: Thermal, Tensile, and Barrier Properties and Effects of Cross-linking

USDA-ARS?s Scientific Manuscript database

Gelatin was extracted from the skins of Alaska pollock (Theragra chalcogramma) and Alaska pink salmon (Oncorhynchus gorbuscha). These skins were by-products generated from the Alaskan fishing industry. Films were then cast from the fish gelatin and their thermal, tensile, water vapor permeability, o...

Analytical Expressions for Thermo-Osmotic Permeability of Clays

NASA Astrophysics Data System (ADS)

Gonçalvès, J.; Ji Yu, C.; Matray, J.-M.; Tremosa, J.

2018-01-01

In this study, a new formulation for the thermo-osmotic permeability of natural pore solutions containing monovalent and divalent cations is proposed. The mathematical formulation proposed here is based on the theoretical framework supporting thermo-osmosis which relies on water structure alteration in the pore space of surface-charged materials caused by solid-fluid electrochemical interactions. The ionic content balancing the surface charge of clay minerals causes a disruption in the hydrogen bond network when more structured water is present at the clay surface. Analytical expressions based on our heuristic model are proposed and compared to the available data for NaCl solutions. It is shown that the introduction of divalent cations reduces the thermo-osmotic permeability by one third compared to the monovalent case. The analytical expressions provided here can be used to advantage for safety calculations in deep underground nuclear waste repositories.

Fault geometry and fluid-rock reaction: Combined controls on mineralization in the Xinli gold deposit, Jiaodong Peninsula, China

NASA Astrophysics Data System (ADS)

Yang, Lin; Zhao, Rui; Wang, Qingfei; Liu, Xuefei; Carranza, Emmanuel John M.

2018-06-01

The structures and fluid-rock reaction in the Xinli gold deposit, Jiaodong Peninsula, were investigated to further understand their combined controls on the development of permeability associated with ore-forming fluid migration. Orebodies in this deposit are hosted by the moderately SE-to S-dipping Sanshandao-Cangshang fault (SCF). Variations in both dip direction and dip angle along the SCF plane produced fault bends, which controlled the fluid accumulation and ore-shoot formation. Gold mineralizations occurred in early gold-quartz-pyrite and late gold-quartz-polymetallic sulphide stages following pervasive sericitization and silicification alterations. Theoretical calculation indicates that sericitization caused 8-57% volume decrease resulting in the development/enlargement of voids, further increase of grain-scale permeability, and resultant precipitation of the early gold-quartz-pyrite pods, which destroyed permeability. The rock softening produced by alterations promoted activities of SCF secondary faults and formation of new fractures, which rebuilt the permeability and controlled the late gold-quartz-polymetallic sulfide veins. Quantitative studies on permeability distributions show that the southwestern and northeastern bend areas with similar alteration and mineralization have persistent and anti-persistent permeability networks, respectively. These were likely caused by different processes of rebuilding permeability due to different stress states resulting from changes in fault geometry.

Quantifying the clay content with borehole depth and impact on reservoir flow

NASA Astrophysics Data System (ADS)

Sarath Kumar, Aaraellu D.; Chattopadhyay, Pallavi B.

2017-04-01

This study focuses on the application of reservoir well log data and 3D transient numerical model for proper optimization of flow dynamics and hydrocarbon potential. Fluid flow through porous media depends on clay content that controls porosity, permeability and pore pressure. The pressure dependence of permeability is more pronounced in tight formations. Therefore, preliminary clay concentration analysis and geo-mechanical characterizations have been done by using wells logs. The assumption of a constant permeability for a reservoir is inappropriate and therefore the study deals with impact of permeability variation for pressure-sensitive formation. The study started with obtaining field data from available well logs. Then, the mathematical models are developed to understand the efficient extraction of oil in terms of reservoir architecture, porosity and permeability. The fluid flow simulations have been done using COMSOL Multiphysics Software by choosing time dependent subsurface flow module that is governed by Darcy's law. This study suggests that the reservoir should not be treated as a single homogeneous structure with unique porosity and permeability. The reservoir parameters change with varying clay content and it should be considered for effective planning and extraction of oil. There is an optimum drawdown for maximum production with varying permeability in a reservoir.

Photocontrolled Cargo Release from Dual Cross-Linked Polymer Particles.

PubMed

Tan, Shereen; Cui, Jiwei; Fu, Qiang; Nam, Eunhyung; Ladewig, Katharina; Ren, Jing M; Wong, Edgar H H; Caruso, Frank; Blencowe, Anton; Qiao, Greg G

2016-03-09

Burst release of a payload from polymeric particles upon photoirradiation was engineered by altering the cross-linking density. This was achieved via a dual cross-linking concept whereby noncovalent cross-linking was provided by cyclodextrin host-guest interactions, and irreversible covalent cross-linking was mediated by continuous assembly of polymers (CAP). The dual cross-linked particles (DCPs) were efficiently infiltrated (∼80-93%) by the biomacromolecule dextran (molecular weight up to 500 kDa) to provide high loadings (70-75%). Upon short exposure (5 s) to UV light, the noncovalent cross-links were disrupted resulting in increased permeability and burst release of the cargo (50 mol % within 1 s) as visualized by time-lapse fluorescence microscopy. As sunlight contains UV light at low intensities, the particles can potentially be incorporated into systems used in agriculture, environmental control, and food packaging, whereby sunlight could control the release of nutrients and antimicrobial agents.

Composite battery separator

NASA Technical Reports Server (NTRS)

Edwards, Dean B. (Inventor); Rippel, Wally E. (Inventor)

1987-01-01

A composite battery separator comprises a support element (10) having an open pore structure such as a ribbed lattice and at least one liquid permeable sheet (20,22) to distribute the compressive force evenly onto the surfaces of the layers (24, 26) of negative active material and positive active material. In a non-flooded battery cell the compressible, porous material (18), such as a glass mat which absorbs the electrolyte, is compressed into a major portion of the pores or openings (16) in the support element. The unfilled pores in the material (18) form a gas diffusion path as the channels (41) formed between adjacent ribs in the lattice element (30,36). Facing two lattice elements (30, 31) with acute angled cross-ribs (34, 38) facing each other prevents the elements from interlocking and distorting a porous, separator (42) disposed between the lattice elements.

Nanostructured silicon membranes for control of molecular transport.

PubMed

Srijanto, Bernadeta R; Retterer, Scott T; Fowlkes, Jason D; Doktycz, Mitchel J

2010-11-01

A membrane that allows selective transport of molecular species requires precise engineering on the nanoscale. Membrane permeability can be tuned by controlling the physical structure and surface chemistry of the pores. Here, a combination of electron beam and optical lithography, along with cryogenic deep reactive ion etching, has been used to fabricate silicon membranes that are physically robust, have uniform pore sizes, and are directly integrated into a microfluidic network. Additional reductions in pore size were achieved using plasma enhanced chemical vapor deposition and atomic layer deposition of silicon dioxide to coat membrane surfaces. Cross sectioning of the membranes using focused ion beam milling was used to determine the physical shape of the membrane pores before and after coating. Functional characterization of the membranes was performed by using quantitative fluorescence microscopy to document the transport of molecular species across the membrane.

Permeability of the Peritrophic Envelopes of Herbivorous Insects to Dextran Sulfate: a Test of the Polyanion Exclusion Hypothesis.

PubMed

MARTIN, M M.; BARBEHENN, R V.

1997-03-01

We tested the hypothesis that the permeability of the peritrophic envelope in herbivorous insects is greatly reduced for polyanions as a result of an extensive network of anionic sites in the proteoglycans of the matrix. 14C-Dextran sulfate (polyanionic, 8000 M(w)) and fluorescein isothiocyanate-labeled (FITC) dextran (monoanionic, 9400 M(w)) were introduced together into the endoperitrophic space of the midguts of Orgyia leucostigma (Lepidoptera) larvae and Melanoplus sanguinipes (Orthoptera) adults. In all cases more of the 14C-dextran sulfate permeated the peritrophic envelope than the FITC-dextran, the opposite of the result predicted by the polyanion exclusion hypothesis. We conclude that polyanion exclusion is not a mechanism that contributes significantly to the permeability properties of the peritrophic envelopes of these two species, or that explains the failure of tannic acid to cross the peritrophic envelopes of lepidopteran larvae. Copyright 1997 Elsevier Science Ltd. All rights reserved

Left-handed transmission in a simple cut-wire pair structure

NASA Astrophysics Data System (ADS)

Tung, Nguyen Thanh; Thuy, Vu Tran Thanh; Park, Jin Woo; Rhee, Joo Yull; Lee, YoungPak

2010-01-01

It is well known that, together with the plasma behavior of continuous wires, the use of cut-wire pair as a metamagnetic component is to drive the negative permeability in the left-handed combined structure. In this study, we have investigated a strange left-handed transmission in a metamaterial consisting of only conventional cut-wire pair structure without additional adjustment. It is shown that the observed left-handed behavior, which occurs at a frequency three times higher than that for the combined structure, originates from the fundamental negative permittivity provided by the symmetric resonant mode and a negative permeability by the third-order asymmetric resonance. Our results would simplify extremely the fabricating procedure, especially, for terahertz regime as well as reveal many possibilities to design optical devices based on the electromagnetic responses of cut-wire structure.

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

Non-invasive optical modulation of local vascular permeability

NASA Astrophysics Data System (ADS)

Choi, Myunghwan; Choi, Chulhee

2011-03-01

For a systemically administered drug to act, it first needs to cross the vascular wall. This step represents a bottleneck for drug development, especially in the brain or retina, where tight junctions between endothelial cells form physiological barriers. Here, we demonstrate that femtosecond pulsed laser irradiation focused on the blood vessel wall induces transient permeabilization of plasma. Nonlinear absorption of the pulsed laser enabled the noninvasive modulation of vascular permeability with high spatial selectivity in three dimensions. By combining this method with systemic injection, we could locally deliver molecular probes in various tissues, such as brain cortex, meninges, ear, striated muscle, and bone. We suggest this method as a novel delivery tool for molecular probes or drugs.

Cage and linear structured polysiloxane/epoxy hybrids for coatings: Surface property and film permeability.

PubMed

Ma, Yanli; He, Ling; Jia, Mengjun; Zhao, Lingru; Zuo, Yanyan; Hu, Pingan

2017-08-15

Three polysiloxane/epoxy hybrids obtained by evolving cage- or linear-structured polysiloxane into poly glycidyl methacrylate (PGMA) matrix are compared used as coatings. One is the cage-structured hybrid of P(GMA/MA-POSS) copolymer obtained by GMA and methacrylisobutyl polyhedral oligomeric silsesquioxane (MA-POSS) via free radical polymerization, the other two are PGMA/NH 2 -POSS and PGMA/NH 2 -PDMS hybrids by cage-structured aminopropyllsobutyl POSS (NH 2 -POSS) or linear-structured diamino terminated poly(dimethylsiloxane) (NH 2 -PDMS) to cure PGMA. The effect of MA-POSS, NH 2 -POSS and NH 2 -PDMS on polysiloxane/epoxy hybrid films is characterized according to their surface morphology, transparency, permeability, adhesive strength and thermo-mechanical properties. Due to caged POSS tending to agglomerate onto the film surface, P(GMA/MA-POSS) and PGMA/NH 2 -POSS films exhibit much more heterogeneous surfaces than PGMA/NH 2 -PDMS film, but the well-compatibility between epoxy matrix and MA-POSS has provided P(GMA/MA-POSS) film with much higher transmittance (98%) than PGMA/NH 2 -POSS film (24%), PGMA/NH 2 -PDMS film (27%) and traditional epoxy resin film (5%). The introduction of polysiloxane into epoxy matrix is confirmed to create hybrids with strong adhesive strength (526-1113N) and high thermos-stability (T g =262-282°C), especially the cage-structured P(GMA/MA-POSS) hybrid (1113N and 282°C), but the flexible PDMS improves PGMA/NH 2 -PDMS hybrid with much higher storage modulus (519MPa) than PGMA/NH 2 -POSS (271MPa), which suggests that PDMS is advantage in improving the film stiffness than POSS cages. However, cage-structured P(GMA/MA-POSS) and PGMA/NH 2 -POSS indicate higher permeability than PGMA/NH 2 -PDMS and traditional epoxy resin. Comparatively, the cage-structured P(GMA/MA-POSS) hybrid is the best coating in transparency, permeability, adhesive strength and thermostability, but linear-structured PGMA/NH 2 -PDMS hybrid behaviors the best coating in mechanical property. Copyright © 2017 Elsevier Inc. All rights reserved.

Geothermal implications of a refined composition-age geologic map for the volcanic terrains of southeast Oregon, northeast California, and southwest Idaho, USA

USGS Publications Warehouse

Burns, Erick; Gannett, Marshall W.; Sherrod, David R.; Keith, Mackenzie K.; Curtis, Jennifer A.; Bartolino, James R.; Engott, John A.; Scandella, Benjamin P.; Stern, Michelle A.; Flint, Alan L.

2017-01-01

Sufficient temperatures to generate steam likely exist under most of the dominantly volcanic terrains of southeast Oregon, northeast California, and southeast Idaho, USA, but finding sufficient permeability to allow efficient advective heat exchange is an outstanding challenge. A new thematic interpretation of existing state-level geologic maps provides an updated and refined distribution of the composition and age of geologic units for the purposes of assessing the implications for measurement and development of geothermal resources. This interpretation has been developed to better understand geothermal and hydrologic resources of the region. Comparison of the new geologic categories with available hydrologic data shows that younger volcanogenic terrains tend to have higher primary permeability than older terrains. Decrease in primary permeability with age is attributable to weathering and hydrothermal alteration of volcanogenic deposits to pore-filling clays and deposition of secondary deposits (e.g., zeolites). Spring density as a function of geology and precipitation can be used to infer groundwater flow path length within the upper aquifers. Beneath the upper aquifers, we postulate that, due to accelerated hydrothermal alteration at temperatures ~>30 °C, primary permeability at depths of geothermal interest will be limited, and that secondary permeability is a more viable target for hydrothermal fluid withdrawal. Because open fractures resulting from tensile stresses will affect all geologic layers, regions with a significant amount of groundwater flow through shallow, structurally controlled secondary permeability may overlay zones of deep secondary permeability. Regardless of whether the shallow permeability is connected with the deep permeability, shallow groundwater flow can mask the presence of deep hydrothermal flow, resulting in blind geothermal systems. Ideally, hydraulic connectivity between shallow and deep secondary permeability is limited, so that shallow groundwater does not cool potential geothermal reservoirs.

Improved reservoir characterisation using fuzzy logic platform: an integrated petrophysical, seismic structural and poststack inversion study

NASA Astrophysics Data System (ADS)

Jafri, Muhammad Kamran; Lashin, Aref; Ibrahim, El-Khedr Hassan; Hassanein, Kamal A.; Al Arifi, Nassir; Naeem, Muhammad

2017-06-01

There is a tendency for applying different integrated geophysical approaches for better hydrocarbon reservoir characterisation and interpretation. In this study, petrophysical properties, seismic structural and poststack seismic inversion results are integrated using the fuzzy logic AND operator to characterise the Tensleep Sandstone Formation (TSF) at Powder River Basin (PRB), Wyoming, USA. TSF is deposited in a coastal plain setting during the Pennsylvanian era, and contains cross-bedded sandstone of Aeolian origin as a major lithology with alternative sabkha dolomite/carbonates. Wireline logging datasets from 17 wells are used for the detailed petrophysical evaluation. Three units of the TSF (A-sandstone, B-dolomite and B-sandstone) are targeted and their major rock properties estimated (i.e. shale/clay volume, Vsh; porosity, φEff permeability, K; fluid saturations, Sw and SH; and bulk volume water, BVW). The B-sandstone zone, with its petrophysical properties of 5-20% effective porosity, 0.10-250 mD permeability and hydrocarbon potential up to 72%, is considered the best reservoir zone among the three studied units. Distributions of the most important petrophysical parameters of the B-sandstone reservoir (Vsh, φEff, K, Sw) are generated as GIS thematic layers. The two-dimensional (2D) and three-dimensional (3D) seismic structural interpretations revealed that the hydrocarbons are entrapped in an anticlinal structure bounded with fault closures at the west of the study area. Poststack acoustic impedance (PSAI) inversion is performed on 3D seismic data to extract the inverted acoustic impedance (AI) cube. Two attribute slices (inverted AI and seismic amplitude) were extracted at the top of the B-sandstone unit as GIS thematic layers. The reservoir properties and inverted seismic attributes were then integrated using fuzzy AND operator. Finally, a fuzzy reservoir quality map was produced, and a prospective reservoir area with best reservoir characteristics is proposed for future exploration. The current study showed that integration of petrophysical, seismic structural and poststack inversion under a fuzzy logic platform can be used as an effective tool for interpreting multiple reservoir zones.

Petrophysics of Lower Silurian sandstones and integration with the tectonic-stratigraphic framework, Appalachian basin, United States

USGS Publications Warehouse

Castle, J.W.; Byrnes, A.P.

2005-01-01

Petrophysical properties were determined for six facies in Lower Silurian sandstones of the Appalachian basin: fluvial, estuarine, upper shoreface, lower shoreface, tidal channel, and tidal flat. Fluvial sandstones have the highest permeability for a given porosity and exhibit a wide range of porosity (2-18%) and permeability (0.002-450 md). With a transition-zone thickness of only 1-6 m (3-20 ft), fluvial sandstones with permeability greater than 5 md have irreducible water saturation (Siw) less than 20%, typical of many gas reservoirs. Upper shoreface sandstones exhibit good reservoir properties with high porosity (10-21%), high permeability (3-250 md), and low S iw (<20%). Lower shoreface sandstones, which are finer grained, have lower porosity (4-12%), lower permeability (0.0007-4 md), thicker transition zones (6-180 m [20-600 ft]), and higher S iw. In the tidal-channel, tidal-flat, and estuarine facies, low porosity (average < 6%), low permeability (average < 0.02 md), and small pore throats result in large transition zones (30-200 m; 100-650 ft) and high water saturations. The most favorable reservoir petrophysical properties and the best estimated production from the Lower Silurian sandstones are associated with fluvial and upper shoreface facies of incised-valley fills, which we interpret to have formed predominantly in areas of structural recesses that evolved from promontories along a collisional margin during the Taconic orogeny. Although the total thickness of the sandstone may not be as great in these areas, reservoir quality is better than in adjacent structural salients, which is attributed to higher energy depositional processes and shallower maximum burial depth in the recesses than in the salients. Copyright ??2005. The American Association of Petroleum Geologists. All rights reserved.

Clay minerals related to the circulation of geothermal fluids in boreholes at Rittershoffen (Alsace, France)

NASA Astrophysics Data System (ADS)

Vidal, Jeanne; Patrier, Patricia; Genter, Albert; Beaufort, Daniel; Dezayes, Chrystel; Glaas, Carole; Lerouge, Catherine; Sanjuan, Bernard

2018-01-01

Two geothermal wells, GRT-1 and GRT-2, were drilled into the granite at Rittershoffen (Alsace, France) in the Upper Rhine Graben to exploit geothermal resources at the sediment-basement interface. Brine circulation occurs in a permeable fracture network and leads to hydrothermal alteration of the host rocks. The goal of the study was to characterize the petrography and mineralogy of the altered rocks with respect to the permeable fracture zones in the granitic basement. As clay minerals are highly reactive to hydrothermal alteration, they can be used as indicators of present-day and paleo-circulation systems. Special attention has been paid to the textural, structural and chemical properties of these minerals. The fine-grained clay fraction (< 5 μm) was analyzed around the originally permeable fracture zones to observe the crystal structure of clay minerals using X-ray diffraction. Chemical microanalysis of the clay minerals was performed using scanning electron microscopy coupled with energy dispersive X-ray spectroscopy. The occurrences of mixed layers illite-smectite ( 10% smectite) provide a promising guide for identifying the fracture zones that control the present-day circulation of geothermal fluids in the Rittershoffen wells. However, multistage paleo-circulation systems could lead to an abundance of heterogeneous and fine-grained illitic minerals that could plug the fracture system. The permeability of fracture zones in the GRT-1 well was likely reduced because of an intense illitization, and the well was stimulated. The occurrence of chlorite in the permeable fracture zones of GRT-2 is indicative of less intense illitization, and the natural permeability is much higher in GRT-2 than in GRT-1.

Modelling the effect of mixture components on permeation through skin.

PubMed

Ghafourian, T; Samaras, E G; Brooks, J D; Riviere, J E

2010-10-15

A vehicle influences the concentration of penetrant within the membrane, affecting its diffusivity in the skin and rate of transport. Despite the huge amount of effort made for the understanding and modelling of the skin absorption of chemicals, a reliable estimation of the skin penetration potential from formulations remains a challenging objective. In this investigation, quantitative structure-activity relationship (QSAR) was employed to relate the skin permeation of compounds to the chemical properties of the mixture ingredients and the molecular structures of the penetrants. The skin permeability dataset consisted of permeability coefficients of 12 different penetrants each blended in 24 different solvent mixtures measured from finite-dose diffusion cell studies using porcine skin. Stepwise regression analysis resulted in a QSAR employing two penetrant descriptors and one solvent property. The penetrant descriptors were octanol/water partition coefficient, logP and the ninth order path molecular connectivity index, and the solvent property was the difference between boiling and melting points. The negative relationship between skin permeability coefficient and logP was attributed to the fact that most of the drugs in this particular dataset are extremely lipophilic in comparison with the compounds in the common skin permeability datasets used in QSAR. The findings show that compounds formulated in vehicles with small boiling and melting point gaps will be expected to have higher permeation through skin. The QSAR was validated internally, using a leave-many-out procedure, giving a mean absolute error of 0.396. The chemical space of the dataset was compared with that of the known skin permeability datasets and gaps were identified for future skin permeability measurements. Copyright 2010 Elsevier B.V. All rights reserved.

Permeability measurements on rock samples from Unzen Scientific Drilling Project Drill Hole 4 (USDP-4)

NASA Astrophysics Data System (ADS)

Watanabe, Tohru; Shimizu, Yuhta; Noguchi, Satoshi; Nakada, Setsuya

2008-07-01

Permeability measurement was made on five rock samples from USDP-4 cores. Rock samples were collected from the conduit zone and its country rock. One sample (C14-1-1) is considered as a part of the feeder dyke for the 1991-1995 eruption. The transient pulse method was employed under confining pressure up to 50 MPa. Compressional wave velocity was measured along with permeability. The measured permeability ranges from 10 - 19 to 10 - 17 m 2 at the atmospheric pressure, and is as low as that reported for tight rocks such as granite. The permeability decreases with increasing confining pressure, while the compressional wave velocity increases. Assuming that pores are parallel elliptical tubes, the pressure dependence of permeability requires aspect ratio of 10 - 4 -10 - 2 at the atmospheric pressure. The pore aperture is estimated to be less than 1 μm. The estimated aspect ratio and pore aperture suggest that connectivity of pores is maintained by narrow cracks. The existence of cracks is supported by the pressure dependence of compressional wave velocity. Narrow cracks (< 1 μm) are observed in dyke samples, and they must have been created after solidification. Dyke samples do not provide us information of pore structures during degassing, since exsolved gas has mostly escaped and pores governing the gas permeable flow should have been lost. Both dyke and country rock samples provide us information of materials around ascending magma. Although the measured small-scale permeability cannot be directly applied to geological-scale processes, it gives constrains on studies of large-scale permeability.

Finite difference modelling of dipole acoustic logs in a poroelastic formation with anisotropic permeability

NASA Astrophysics Data System (ADS)

He, Xiao; Hu, Hengshan; Wang, Xiuming

2013-01-01

Sedimentary rocks can exhibit strong permeability anisotropy due to layering, pre-stresses and the presence of aligned microcracks or fractures. In this paper, we develop a modified cylindrical finite-difference algorithm to simulate the borehole acoustic wavefield in a saturated poroelastic medium with transverse isotropy of permeability and tortuosity. A linear interpolation process is proposed to guarantee the leapfrog finite difference scheme for the generalized dynamic equations and Darcy's law for anisotropic porous media. First, the modified algorithm is validated by comparison against the analytical solution when the borehole axis is parallel to the symmetry axis of the formation. The same algorithm is then used to numerically model the dipole acoustic log in a borehole with its axis being arbitrarily deviated from the symmetry axis of transverse isotropy. The simulation results show that the amplitudes of flexural modes vary with the dipole orientation because the permeability tensor of the formation is dependent on the wellbore azimuth. It is revealed that the attenuation of the flexural wave increases approximately linearly with the radial permeability component in the direction of the transmitting dipole. Particularly, when the borehole axis is perpendicular to the symmetry axis of the formation, it is possible to estimate the anisotropy of permeability by evaluating attenuation of the flexural wave using a cross-dipole sonic logging tool according to the results of sensitivity analyses. Finally, the dipole sonic logs in a deviated borehole surrounded by a stratified porous formation are modelled using the proposed finite difference code. Numerical results show that the arrivals and amplitudes of transmitted flexural modes near the layer interface are sensitive to the wellbore inclination.

In vitro blood-brain barrier permeability predictions for GABAA receptor modulating piperine analogs.

PubMed

Eigenmann, Daniela Elisabeth; Dürig, Carmen; Jähne, Evelyn Andrea; Smieško, Martin; Culot, Maxime; Gosselet, Fabien; Cecchelli, Romeo; Helms, Hans Christian Cederberg; Brodin, Birger; Wimmer, Laurin; Mihovilovic, Marko D; Hamburger, Matthias; Oufir, Mouhssin

2016-06-01

The alkaloid piperine from black pepper (Piper nigrum L.) and several synthetic piperine analogs were recently identified as positive allosteric modulators of γ-aminobutyric acid type A (GABAA) receptors. In order to reach their target sites of action, these compounds need to enter the brain by crossing the blood-brain barrier (BBB). We here evaluated piperine and five selected analogs (SCT-66, SCT-64, SCT-29, LAU397, and LAU399) regarding their BBB permeability. Data were obtained in three in vitro BBB models, namely a recently established human model with immortalized hBMEC cells, a human brain-like endothelial cells (BLEC) model, and a primary animal (bovine endothelial/rat astrocytes co-culture) model. For each compound, quantitative UHPLC-MS/MS methods in the range of 5.00-500ng/mL in the corresponding matrix were developed, and permeability coefficients in the three BBB models were determined. In vitro predictions from the two human BBB models were in good agreement, while permeability data from the animal model differed to some extent, possibly due to protein binding of the screened compounds. In all three BBB models, piperine and SCT-64 displayed the highest BBB permeation potential. This was corroborated by data from in silico prediction. For the other piperine analogs (SCT-66, SCT-29, LAU397, and LAU399), BBB permeability was low to moderate in the two human BBB models, and moderate to high in the animal BBB model. Efflux ratios (ER) calculated from bidirectional permeability experiments indicated that the compounds were likely not substrates of active efflux transporters. Copyright © 2016 Elsevier B.V. All rights reserved.

Classification of cassava starch films by physicochemical properties and water vapor permeability quantification by FTIR and PLS.

PubMed

Henrique, C M; Teófilo, R F; Sabino, L; Ferreira, M M C; Cereda, M P

2007-05-01

Cassava starches are widely used in the production of biodegradable films, but their resistance to humidity migration is very low. In this work, commercial cassava starch films were studied and classified according to their physicochemical properties. A nondestructive method for water vapor permeability determination, which combines with infrared spectroscopy and multivariate calibration, is also presented. The following commercial cassava starches were studied: pregelatinized (amidomax 3550), carboxymethylated starch (CMA) of low and high viscosities, and esterified starches. To make the films, 2 different starch concentrations were evaluated, consisting of water suspensions with 3% and 5% starch. The filmogenic solutions were dried and characterized for their thickness, grammage, water vapor permeability, water activity, tensile strength (deformation force), water solubility, and puncture strength (deformation). The minimum thicknesses were 0.5 to 0.6 mm in pregelatinized starch films. The results were treated by means of the following chemometric methods: principal component analysis (PCA) and partial least squares (PLS) regression. PCA analysis on the physicochemical properties of the films showed that the differences in concentration of the dried material (3% and 5% starch) and also in the type of starch modification were mainly related to the following properties: permeability, solubility, and thickness. IR spectra collected in the region of 4000 to 600 cm(-1) were used to build a PLS model with good predictive power for water vapor permeability determination, with mean relative errors of 10.0% for cross-validation and 7.8% for the prediction set.

Electrokinetic Enhanced Permanganate Delivery for Low Permeability Soil Remediation

NASA Astrophysics Data System (ADS)

Chowdhury, A. I.; Gerhard, J.; Reynolds, D. A.; Sleep, B. E.; O'Carroll, D. M.

2016-12-01

Contaminant mass sequestered in low permeability zones (LPZ) in the subsurface has become a significant concern due to back diffusion of contaminants, leading to contaminant rebound following treatment of the high permeability strata. In-situ remediation technologies such as in-situ chemical oxidation (ISCO) are promising, however, successful delivery of oxidants into silts and clays remains a challenge. Electrokinetics (EK) has been proposed as a technique that can overcome this challenge by delivering oxidants into low permeability soils. This study demonstrates the ability of EK to facilitate permanganate delivery into silt for treatment of trichloroethene (TCE). A two-dimensional sandbox was packed with alternate vertical layers of coarse sand and silt contaminated with high concentrations of aqueous phase TCE. Nine experiments were conducted to compare EK-enhanced in-situ chemical oxidation (EK-ISCO) to ISCO alone or EK alone. Frequent groundwater sampling at multiple locations combined with image analysis provided detailed mapping of TCE, permanganate, and manganese dioxide mass distributions. EK-ISCO successfully delivered the permanganate throughout the silt cross-section while ISCO without EK resulted in permanganate delivery only to the edges of the silt layer. EK-ISCO resulted in a 4.4 order-of-magnitude (OoM) reduction in TCE concentrations in the coarse sand compared to a 3.5 OoM reduction for ISCO alone. This study suggests that electrokinetics coupled with ISCO can achieve enhanced remediation of lower permeability strata, where remediation technologies for successful contaminant mass removal would otherwise be limited.

Multi-center prediction of hemorrhagic transformation in acute ischemic stroke using permeability imaging features.

PubMed

Scalzo, Fabien; Alger, Jeffry R; Hu, Xiao; Saver, Jeffrey L; Dani, Krishna A; Muir, Keith W; Demchuk, Andrew M; Coutts, Shelagh B; Luby, Marie; Warach, Steven; Liebeskind, David S

2013-07-01

Permeability images derived from magnetic resonance (MR) perfusion images are sensitive to blood-brain barrier derangement of the brain tissue and have been shown to correlate with subsequent development of hemorrhagic transformation (HT) in acute ischemic stroke. This paper presents a multi-center retrospective study that evaluates the predictive power in terms of HT of six permeability MRI measures including contrast slope (CS), final contrast (FC), maximum peak bolus concentration (MPB), peak bolus area (PB), relative recirculation (rR), and percentage recovery (%R). Dynamic T2*-weighted perfusion MR images were collected from 263 acute ischemic stroke patients from four medical centers. An essential aspect of this study is to exploit a classifier-based framework to automatically identify predictive patterns in the overall intensity distribution of the permeability maps. The model is based on normalized intensity histograms that are used as input features to the predictive model. Linear and nonlinear predictive models are evaluated using a cross-validation to measure generalization power on new patients and a comparative analysis is provided for the different types of parameters. Results demonstrate that perfusion imaging in acute ischemic stroke can predict HT with an average accuracy of more than 85% using a predictive model based on a nonlinear regression model. Results also indicate that the permeability feature based on the percentage of recovery performs significantly better than the other features. This novel model may be used to refine treatment decisions in acute stroke. Copyright © 2013 Elsevier Inc. All rights reserved.

Stochastic Representation and Uncertainty Assessment of a Deep Geothermal Reservoir Using Cross-Borehole ERT: A 3D Synthetic Case

NASA Astrophysics Data System (ADS)

Brunet, P.; Gloaguen, E.

2014-12-01

Designing and monitoring of geothermal systems is a complex task which requires a multidisciplinary approach. Deep geothermal reservoir models are prone to greater uncertainty, with a lack of direct data and lower resolution of surface geophysical methods. However, recent technical advances have enabled the potential use of permanent downhole vertical resistivity arrays for monitoring fluid injection. As electrical resistivity is sensitive to temperature changes, such data could provide valuable information for deep geothermal reservoir characterization. The objective of this study is to assess the potential of time-lapse cross-borehole ERT to constrain 3D realizations of geothermal reservoir properties. The synthetic case of a permeable geothermal reservoir in a sedimentary basin was set up, as a confined deep and saline sandstone aquifer with intermediate reservoir temperatures (150ºC), depth (1 km) and 30m thickness. The reservoir permeability distribution is heterogeneous, as the result of a fluvial depositional environment. The ERT monitoring system design is a triangular arrangement of 3 wells at 150 m spacing, including 1 injection and 1 extraction well. The optimal number and spacing of electrodes of the ERT array design is site-specific and has been assessed through a sensibility study. Dipole-dipole and pole-pole electrode configurations were used. The study workflow was the following: 1) Generation of a reference reservoir model and 100 stochastic realizations of permeability; 2) Simulation of saturated single-phase flow and heat transport of reinjection of cooled formation fluid (50ºC) with TOUGH2 software; 3) Time-lapse forward ERT modeling on the reference model and all realizations (observed and simulated apparent resistivity change); 4) heuristic optimization on ERT computed and calculated data. Preliminary results show significant reduction of parameter uncertainty, hence realization space, with assimilation of cross-borehole ERT data. Loss in sensitivity of ERT between boreholes is compensated here by the stochastic modeling approach, rather than using a deterministic inversion scheme. Our results suggest stochastic reservoir simulations, together with assimilation of cross-borehole ERT data, could be useful tools for design and monitoring of deep geothermal systems.

In situ oil shale retort with a generally T-shaped vertical cross section

DOEpatents

Ricketts, Thomas E.

1981-01-01

An in situ oil shale retort is formed in a subterranean formation containing oil shale. The retort contains a fragmented permeable mass of formation particles containing oil shale and has a production level drift in communication with a lower portion of the fragmented mass for withdrawing liquid and gaseous products of retorting during retorting of oil shale in the fragmented mass. The principal portion of the fragmented mass is spaced vertically above a lower production level portion having a generally T-shaped vertical cross section. The lower portion of the fragmented mass has a horizontal cross sectional area smaller than the horizontal cross sectional area of the upper principal portion of the fragmented mass above the production level.

Mapping Cd²⁺-induced membrane permeability changes of single live cells by means of scanning electrochemical microscopy.

PubMed

Filice, Fraser P; Li, Michelle S M; Henderson, Jeffrey D; Ding, Zhifeng

2016-02-18

Scanning Electrochemical Microscopy (SECM) is a powerful, non-invasive, analytical methodology that can be used to investigate live cell membrane permeability. Depth scan SECM imaging allowed for the generation of 2D current maps of live cells relative to electrode position in the x-z or y-z plane. Depending on resolution, one depth scan image can contain hundreds of probe approach curves (PACs). Individual PACs were obtained by simply extracting vertical cross-sections from the 2D image. These experimental PACs were overlaid onto theoretically generated PACs simulated at specific geometry conditions. Simulations were carried out using 3D models in COMSOL Multiphysics to determine the cell membrane permeability coefficients at different locations on the surface of the cells. Common in literature, theoretical PACs are generated using a 2D axially symmetric geometry. This saves on both compute time and memory utilization. However, due to symmetry limitations of the model, only one experimental PAC right above the cell can be matched with simulated PAC data. Full 3D models in this article were developed for the SECM system of live cells, allowing all experimental PACs over the entire cell to become usable. Cd(2+)-induced membrane permeability changes of single human bladder (T24) cells were investigated at several positions above the cell, displaced from the central axis. The experimental T24 cells under study were incubated with Cd(2+) in varying concentrations. It is experimentally observed that 50 and 100 μM Cd(2+) caused a decrease in membrane permeability, which was uniform across all locations over the cell regardless of Cd(2+) concentration. The Cd(2+) was found to have detrimental effects on the cell, with cells shrinking in size and volume, and the membrane permeability decreasing. A mapping technique for the analysis of the cell membrane permeability under the Cd(2+) stress is realized by the methodology presented. Copyright © 2016 Elsevier B.V. All rights reserved.

Influence of overconsolidated condition on permeability evolution in silica sand

NASA Astrophysics Data System (ADS)

Kimura, S.; Kaneko, H.; Ito, T.; Nishimura, O.; Minagawa, H.

2013-12-01

Permeability of sediments is important factors for production of natural gas from natural gas hydrate bearing layers. Methane-hydrate is regarded as one of the potential resources of natural gas. As results of coring and logging, the existence of a large amount of methane-hydrate is estimated in the Nankai Trough, offshore central Japan, where many folds and faults have been observed. In the present study, we investigate the permeability of silica sand specimen forming the artificial fault zone after large displacement shear in the ring-shear test under two different normal consolidated and overconsolidated conditions. The significant influence of overconsolidation ratio (OCR) on permeability evolution is not found. The permeability reduction is influenced a great deal by the magnitude of normal stress during large displacement shearing. The grain size distribution and structure observation in the shear zone of specimen after shearing at each normal stress level are analyzed by laser scattering type particle analyzer and scanning electron microscope, respectively. It is indicated that the grain size and porosity reduction due to the particle crushing are the factor of the permeability reduction. This study is financially supported by METI and Research Consortium for Methane Hydrate Resources in Japan (the MH21 Research Consortium).

The Permeability of the Sodium Channel to Metal Cations in Myelinated Nerve

PubMed Central

Hille, Bertil

1972-01-01

The relative permeability of sodium channels to eight metal cations is studied in myelinated nerve fibers. Ionic currents under voltage-clamp conditions are measured in Na-free solutions containing the test ion. Measured reversal potentials and the Goldman equation are used to calculate the permeability sequence: Na+ ≈ Li+ > Tl+ > K+. The ratio P K/P Na is 1/12. The permeabilities to Rb+, Cs+, Ca++, and Mg++ are too small to measure. The permeability ratios agree with observations on the squid giant axon and show that the reversal potential E Na differs significantly from the Nernst potential for Na+ in normal axons. Opening and closing rates for sodium channels are relatively insensitive to the ionic composition of the bathing medium, implying that gating is a structural property of the channel rather than a result of the movement or accumulation of particular ions around the channel. A previously proposed pore model of the channel accommodates the permeant metal cations in a partly hydrated form. The observed sequence of permeabilities follows the order expected for binding to a high field strength anion in Eisenman's theory of ion exchange equilibria. PMID:5025743

Optimization of the Caco-2 permeability assay to screen drug compounds for intestinal absorption and efflux.

PubMed

Press, Barry

2011-01-01

In vitro permeability assays are a valuable tool for scientists during lead compound optimization. As a majority of discovery projects are focused on the development of orally bioavailable drugs, correlation of in vitro permeability data to in vivo absorption results is critical for understanding the structural-physicochemical relationship (SPR) of drugs exhibiting low levels of absorption. For more than a decade, the Caco-2 screening assay has remained a popular, in vitro system to test compounds for both intestinal permeability and efflux liability. Despite advances in artificial membrane technology and in silico modeling systems, drug compounds still benefit from testing in cell-based epithelial monolayer assays for lead optimization. This chapter provides technical information for performing and optimizing the Caco-2 assay. In addition, techniques are discussed for dealing with some of the most pressing issues surrounding in vitro permeability assays (i.e., low aqueous solubility of test compounds and low postassay recovery). Insights are offered to help researchers avoid common pitfalls in the interpretation of in vitro permeability data, which can often lead to the perception of misleading results for correlation to in vivo data.

Gas permeability of ice-templated, unidirectional porous ceramics.

PubMed

Seuba, Jordi; Deville, Sylvain; Guizard, Christian; Stevenson, Adam J

2016-01-01

We investigate the gas flow behavior of unidirectional porous ceramics processed by ice-templating. The pore volume ranged between 54% and 72% and pore size between 2.9 [Formula: see text]m and 19.1 [Formula: see text]m. The maximum permeability ([Formula: see text] [Formula: see text] m[Formula: see text]) was measured in samples with the highest total pore volume (72%) and pore size (19.1 [Formula: see text]m). However, we demonstrate that it is possible to achieve a similar permeability ([Formula: see text] [Formula: see text] m[Formula: see text]) at 54% pore volume by modification of the pore shape. These results were compared with those reported and measured for isotropic porous materials processed by conventional techniques. In unidirectional porous materials tortuosity ([Formula: see text]) is mainly controlled by pore size, unlike in isotropic porous structures where [Formula: see text] is linked to pore volume. Furthermore, we assessed the applicability of Ergun and capillary model in the prediction of permeability and we found that the capillary model accurately describes the gas flow behavior of unidirectional porous materials. Finally, we combined the permeability data obtained here with strength data for these materials to establish links between strength and permeability of ice-templated materials.

Defects level evaluation of LiTiZn ferrite ceramics using temperature dependence of initial permeability

NASA Astrophysics Data System (ADS)

Malyshev, A. V.; Petrova, A. B.; Sokolovskiy, A. N.; Surzhikov, A. P.

2018-06-01

The method for evaluating the integral defects level and chemical homogeneity of ferrite ceramics based on temperature dependence analysis of initial permeability is suggested. A phenomenological expression for the description of such dependence was suggested and an interpretation of its main parameters was given. It was shown, that the main criterion of the integral defects level of ferrite ceramics is relation of two parameters correlating with elastic stress value in a material. An indicator of structural perfection can be a maximum value of initial permeability close to Curie point as well. The temperature dependences of initial permeability have analyzed for samples sintered in laboratory conditions and for the ferrite industrial product. The proposed method allows controlling integral defects level of the soft ferrite products and has high sensitivity compare to typical X-ray methods.

Study of the internal morphology of cation-exchange membranes by means of electroosmotic permeability relaxations.

PubMed

Barragán, V M; Izquierdo-Gil, M A; Godino, M P; Villaluenga, J P G

2009-10-01

The effect of an ac sinusoidal perturbation of known amplitude and frequency superimposed to the usual dc applied electric voltage difference on the electroosmotic flow through three cation-exchange membranes with different morphology has been studied. A dispersion of the electroosmotic permeability on the frequency of the applied ac signal has been found for the three membranes investigated, observing that the electroosmotic permeability reaches maximum values for some characteristic values of the frequency. These characteristic frequency values, which are related to relaxation processes in heterogeneous media, depend on the membrane system and permit to obtain information about the different structures of the membrane system. Thus, the study of the electroosmotic permeability relaxation can be used as a method to study the internal morphology of a cation-exchange membrane in a given electrolyte medium.

Permeability structure and its influence on microbial activity at off-Shimokita basin, Japan

NASA Astrophysics Data System (ADS)

Tanikawa, W.; Yamada, Y.; Sanada, Y.; Kubo, Y.; Inagaki, F.

2016-12-01

The microbial populations and the limit of microbial life are probably limited by chemical, physical, and geological conditions, such as temperature, pore water chemistry, pH, and water activity; however, the key parameters affecting growth in deep subseafloor sediments remain unclarified (Hinrichs and Inagaki 2012). IODP expedition 337 was conducted near a continental margin basin off Shimokita Peninsula, Japan to investigate the microbial activity under deep marine coalbed sediments down to 2500 mbsf. Inagaki et al. (2015) discovered that microbial abundance decreased markedly with depth (the lowest cell density of <1 cell/cm3 was recorded below 2000 mbsf), and that the coal bed layers had relatively higher cell densities. In this study, permeability was measured on core samples from IODP Expedition 337 and Expedition CK06-06 in the D/V Chikyu shakedown cruise. Permeability was measured at in-situ effective pressure condition. Permeability was calculated by the steady state flow method by keeping differential pore pressure from 0.1 to 0.8 MPa.Our results show that the permeability for core samples decreases with depth from 10-16 m2 on the seafloor to 10-20 m2 at the bottom of hole. However, permeability is highly scattered within the coal bed unit (1900 to 2000 mbsf). Permeabilities for sandstone and coal is higher than those for siltstone and shale, therefore the scatter of the permeabilities at the same unit is due to the high variation of lithology. The highest permeability was observed in coal samples and this is probably due to formation of micro cracks (cleats). Permeability estimated from the NMR logging using the empirical parameters is around two orders of magnitude higher than permeability of core samples, even though the relative permeability variation at vertical direction is quite similar between core and logging data.The higher cell density is observed in the relatively permeable formation. On the other hand, the correlation between cell density, water activity, and porosity is not clear. On the assumption that pressure gradient is constant through the depth, flow rate can be proportional to permeability of sediments. Flow rate probably restricts the availability of energy and nutrient for microorganism, therefore permeability might have influenced on the microbial activity in the coalbed basin.

Microstructural observations of reconsolidated granular salt to 250°C

NASA Astrophysics Data System (ADS)

Mills, M. M.; Hansen, F.; Bauer, S. J.; Stormont, J.

2014-12-01

Very low permeability is a principal reason salt formations are considered viable hosts for disposal of nuclear waste and spent nuclear fuel. Granular salt is likely to be used as back-fill material and as a seal system component. Granular salt is expected to reconsolidate to a low permeability condition because of external pressure from the surrounding salt formation. Understanding the consolidation processes--known to depend on the stress state, moisture availability and temperature--is important for predicting achievement of sealing functions and long-term repository performance. As granular salt consolidates, initial void reduction is accomplished by brittle processes of grain rearrangement and cataclastic flow. At porosities of less than 10%, grain boundary processes and crystal-plastic mechanisms govern further porosity reduction. We investigate the micro-mechanisms operative in granular salt that has been consolidated under high temperatures to relatively low porosity. These conditions would occur proximal to heat-generating canisters. Mine-run salt from the Waste Isolation Pilot Plant was used to create cylindrical samples which were consolidated at 250°C and stresses to 20 MPa. From samples consolidated to fractional densities of 86% and 97% polished thin sections, etched cleavage chips, and fragments were fabricated. Microstructural techniques included scanning electron and optical microscopy. Microstructure of undeformed mine-run salt was compared to the deformed granular salt. Observed deformation mechanisms include glide, cross slip, climb, fluid-assisted creep, pressure-solution redeposition, and annealing. Documentation of operative deformation mechanisms within the consolidating granular salt, particularly at grain boundaries, is essential to establish effects of moisture, stress, and temperature. Future work will include characterization of pore structures. Information gleaned in these studies supports evaluation of a constitutive model for reconsolidating granular salt, which will be used to predict the thermal-mechanical-hydrologic response of salt repository seal structures and backfilled rooms.

Ultrasound-Enhanced Delivery of Antibiotics and Anti-Inflammatory Drugs into the Eye

PubMed Central

Nabili, Marjan; Patel, Hetal; Mahesh, Sankaranarayana P.; Liu, Ji; Geist, Craig; Zderic, Vesna

2013-01-01

Delivery of sufficient amounts of therapeutic drugs into the eye is often a challenging task. In this study, ultrasound application (frequencies of 400 KHz to 1 MHz, intensities of 0.3–1.0 W/cm2 and exposure duration of 5 min) was investigated to overcome the barrier properties of cornea, which is a typical route for topical administration of ophthalmic drugs. Permeability of ophthalmic drugs, tobramycin and dexamethasone and sodium fluorescein, a drug-mimicking compound, was studied in ultrasound- and sham-treated rabbit corneas in vitro using a standard diffusion cell setup. Light microscopy observations were used to determine ultrasound-induced structural changes in the cornea. For tobramycin, an increase in permeability for ultrasound- and sham-treated corneas was not statistically significant. Increase of 46%–126% and 32%–109% in corneal permeability was observed for sodium fluorescein and dexamethasone, respectively, with statistical significance (p < 0.05) achieved at all treatment parameter combinations (compared with sham treatments) except for 1-MHz ultrasound applications for dexamethasone experiments. This permeability increase was highest at 400 kHz and appeared to be higher at higher intensities applied. Histologic analysis showed structural changes that were limited to epithelial layers of cornea. In summary, ultrasound application provided enhancement of drug delivery, increasing the permeability of the cornea for the anti-inflammatory ocular drug dexamethasone. Future investigations are needed to determine the effectiveness and safety of this application in in vivo long-term survival studies. (E-mail: mnabili@gwu.edu) PMID:23415283

Fine-tuning the physicochemical properties of peptide-based blood-brain barrier shuttles.

PubMed

Ghasemy, Somaye; García-Pindado, Júlia; Aboutalebi, Fatemeh; Dormiani, Kianoush; Teixidó, Meritxell; Malakoutikhah, Morteza

2018-05-01

N-methylation is a powerful method to modify the physicochemical properties of peptides. We previously found that a fully N-methylated tetrapeptide, Ac-(N-MePhe) 4 -CONH 2 , was more lipophilic than its non-methylated analog Ac-(Phe) 4 -CONH 2 . In addition, the former crossed artificial and cell membranes while the latter did not. Here we sought to optimize the physicochemical properties of peptides and address how the number and position of N-methylated amino acids affect these properties. To this end, 15 analogs of Ac-(Phe) 4 -CONH 2 were designed and synthesized in solid-phase. The solubility of the peptides in water and their lipophilicity, as measured by ultra performance liquid chromatography (UPLC) retention times, were determined. To study the permeability of the peptides, the Parallel Artificial Membrane Permeability Assay (PAMPA) was used as an in vitro model of the blood-brain barrier (BBB). Contrary to the parent peptide, the 15 analogs crossed the artificial membrane, thereby showing that N-methylation improved permeability. We also found that N-methylation enhanced lipophilicity but decreased the water solubility of peptides. Our results showed that both the number and position of N-methylated residues are important factors governing the physicochemical properties of peptides. There was no correlation between the number of N-methylated amide bonds and any of the properties measured. However, for the peptides consecutively N-methylated from the N-terminus to the C-terminus (p1, p5, p11, p12 and p16), lipophilicity correlated well with the number of N-methylated amide bonds and the permeability of the peptides. Moreover, the peptides were non-toxic to HEK293T cells, as determined by the 3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium (MTS) assay. Copyright © 2018 Elsevier Ltd. All rights reserved.

Fault current limiter

DOEpatents

Darmann, Francis Anthony

2013-10-08

A fault current limiter (FCL) includes a series of high permeability posts for collectively define a core for the FCL. A DC coil, for the purposes of saturating a portion of the high permeability posts, surrounds the complete structure outside of an enclosure in the form of a vessel. The vessel contains a dielectric insulation medium. AC coils, for transporting AC current, are wound on insulating formers and electrically interconnected to each other in a manner such that the senses of the magnetic field produced by each AC coil in the corresponding high permeability core are opposing. There are insulation barriers between phases to improve dielectric withstand properties of the dielectric medium.

Permeability, storage and hydraulic diffusivity controlled by earthquakes

NASA Astrophysics Data System (ADS)

Brodsky, E. E.; Fulton, P. M.; Xue, L.

2016-12-01

Earthquakes can increase permeability in fractured rocks. In the farfield, such permeability increases are attributed to seismic waves and can last for months after the initial earthquake. Laboratory studies suggest that unclogging of fractures by the transient flow driven by seismic waves is a viable mechanism. These dynamic permeability increases may contribute to permeability enhancement in the seismic clouds accompanying hydraulic fracking. Permeability enhancement by seismic waves could potentially be engineered and the experiments suggest the process will be most effective at a preferred frequency. We have recently observed similar processes inside active fault zones after major earthquakes. A borehole observatory in the fault that generated the M9.0 2011 Tohoku earthquake reveals a sequence of temperature pulses during the secondary aftershock sequence of an M7.3 aftershock. The pulses are attributed to fluid advection by a flow through a zone of transiently increased permeability. Directly after the M7.3 earthquake, the newly damaged fault zone is highly susceptible to further permeability enhancement, but ultimately heals within a month and becomes no longer as sensitive. The observation suggests that the newly damaged fault zone is more prone to fluid pulsing than would be expected based on the long-term permeability structure. Even longer term healing is seen inside the fault zone of the 2008 M7.9 Wenchuan earthquake. The competition between damage and healing (or clogging and unclogging) results in dynamically controlled permeability, storage and hydraulic diffusivity. Recent measurements of in situ fault zone architecture at the 1-10 meter scale suggest that active fault zones often have hydraulic diffusivities near 10-2 m2/s. This uniformity is true even within the damage zone of the San Andreas fault where permeability and storage increases balance each other to achieve this value of diffusivity over a 400 m wide region. We speculate that fault zones may evolve to a preferred diffusivity in a dynamic equilibrium.

Understanding fluid transport through the multiscale pore network of a natural shale

NASA Astrophysics Data System (ADS)

Davy, Catherine A.; Nguyen Kim, Thang; Song, Yang; Troadec, David; Blanchenet, Anne-Marie; Adler, Pierre M.

2017-06-01

The pore structure of a natural shale is obtained by three imaging means. Micro-tomography results are extended to provide the spatial arrangement of the minerals and pores present at a voxel size of 700 nm (the macroscopic scale). FIB/SEM provides a 3D representation of the porous clay matrix on the so-called mesoscopic scale (10-20 nm); a connected pore network, devoid of cracks, is obtained for two samples out of five, while the pore network is connected through cracks for two other samples out of five. Transmission Electron Microscopy (TEM) is used to visualize the pore space with a typical pixel size of less than 1 nm and a porosity ranging from 0.12 to 0.25. On this scale, in the absence of 3D images, the pore structure is reconstructed by using a classical technique, which is based on truncated Gaussian fields. Permeability calculations are performed with the Lattice Boltzmann Method on the nanoscale, on the mesoscale, and on the combination of the two. Upscaling is finally done (by a finite volume approach) on the bigger macroscopic scale. Calculations show that, in the absence of cracks, the contribution of the nanoscale pore structure on the overall permeability is similar to that of the mesoscale. Complementarily, the macroscopic permeability is measured on a centimetric sample with a neutral fluid (ethanol). The upscaled permeability on the macroscopic scale is in good agreement with the experimental results.

Electro-osmosis of non-Newtonian fluids in porous media using lattice Poisson-Boltzmann method.

PubMed

Chen, Simeng; He, Xinting; Bertola, Volfango; Wang, Moran

2014-12-15

Electro-osmosis in porous media has many important applications in various areas such as oil and gas exploitation and biomedical detection. Very often, fluids relevant to these applications are non-Newtonian because of the shear-rate dependent viscosity. The purpose of this study was to investigate the behaviors and physical mechanism of electro-osmosis of non-Newtonian fluids in porous media. Model porous microstructures (granular, fibrous, and network) were created by a random generation-growth method. The nonlinear governing equations of electro-kinetic transport for a power-law fluid were solved by the lattice Poisson-Boltzmann method (LPBM). The model results indicate that: (i) the electro-osmosis of non-Newtonian fluids exhibits distinct nonlinear behaviors compared to that of Newtonian fluids; (ii) when the bulk ion concentration or zeta potential is high enough, shear-thinning fluids exhibit higher electro-osmotic permeability, while shear-thickening fluids lead to the higher electro-osmotic permeability for very low bulk ion concentration or zeta potential; (iii) the effect of the porous medium structure depends significantly on the constitutive parameters: for fluids with large constitutive coefficients strongly dependent on the power-law index, the network structure shows the highest electro-osmotic permeability while the granular structure exhibits the lowest permeability on the entire range of power law indices considered; when the dependence of the constitutive coefficient on the power law index is weaker, different behaviors can be observed especially in case of strong shear thinning. Copyright © 2014 Elsevier Inc. All rights reserved.

Effects of clay dispersion on aquifer storage and recovery in coastal aquifers

USGS Publications Warehouse

Konikow, Leonard F.; August, L.L.; Voss, C.I.

2001-01-01

Cyclic injection, storage, and withdrawal of freshwater in brackish aquifers is a form of aquifer storage and recovery (ASR) that can beneficially supplement water supplies in coastal areas. A 1970s field experiment in Norfolk, Virginia, showed that clay dispersion in the unconsolidated sedimentary aquifer occurred because of cation exchange on clay minerals as freshwater displaced brackish formation water. Migration of interstitial clay particles clogged pores, reduced permeability, and decreased recovery efficiency, but a calcium preflush was found to reduce clay dispersion and lead to a higher recovery efficiency. Column experiments were performed in this study to quantify the relations between permeability changes and clay mineralogy, clay content, and initial water salinity. The results of these experiments indicate that dispersion of montmorillonite clay is a primary contributor to formation damage. The reduction in permeability by clay dispersion may be expressed as a linear function of chloride content. Incorporating these simple functions into a radial, cross-sectional, variable-density, ground-water flow and transport model yielded a satisfactory simulation of the Norfolk field test - and represented an improvement over the model that ignored changes in permeability. This type of model offers a useful planning and design tool for ASR operations in coastal clastic aquifer systems.

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

Silin, D.; Goloshubin, G.

Analysis of compression wave propagation in a poroelastic medium predicts a peak of reflection from a high-permeability layer in the low-frequency end of the spectrum. An explicit formula expresses the resonant frequency through the elastic moduli of the solid skeleton, the permeability of the reservoir rock, the fluid viscosity and compressibility, and the reservoir thickness. This result is obtained through a low-frequency asymptotic analysis of Biot's model of poroelasticity. A review of the derivation of the main equations from the Hooke's law, momentum and mass balance equations, and Darcy's law suggests an alternative new physical interpretation of some coefficients ofmore » the classical poroelasticity. The velocity of wave propagation, the attenuation factor, and the wave number, are expressed in the form of power series with respect to a small dimensionless parameter. The absolute value of this parameter is equal to the product of the kinematic reservoir fluid mobility and the wave frequency. Retaining only the leading terms of the series leads to explicit and relatively simple expressions for the reflection and transmission coefficients for a planar wave crossing an interface between two permeable media, as well as wave reflection from a thin highly-permeable layer (a lens). Practical applications of the obtained asymptotic formulae are seismic modeling, inversion, and at-tribute analysis.« less

Novel antifouling nano-enhanced thin-film composite membrane containing cross-linkable acrylate-alumoxane nanoparticles for water softening.

PubMed

Ghaemi, Negin

2017-01-01

A novel thin-film composite (TFC) nanofiltration membrane was prepared using polymerization of pyrrole monomers on the PES ultrafiltration membrane. To improve the characteristics of hydrophobic polypyrrole (PPy) thin-film layer, cross-linkable acrylate-functionalized alumoxane nanoparticles with different concentrations were embedded into the thin-film during polymerization process, and thin-film nanocomposite (TFNC) membranes were prepared. The characteristics and performance of TFC and TFNC membranes were assessed through the morphological analyses (SEM, AFM), measurement of hydrophilicity and solid-liquid interfacial free energy, water permeability and Mg 2+ removal tests. Addition of proper amount of nanoparticles into the polymerization mixture led to the preparation of membranes with more hydrophilic, thinner and smoother active layer as well as higher water permeability compared to TFC control membrane. TFNC membrane prepared with 0.025g of nanoparticles was the most efficient membrane since it exhibited the highest rejection of MgCl 2 and MgSO 4 salts. Antifouling capability of membranes, in terms of flux recovery and fouling parameters, demonstrated the high tolerance of TFNC against fouling. Copyright © 2016 Elsevier Inc. All rights reserved.

Α-aryl-N-alkyl nitrones, as potential agents for stroke treatment: synthesis, theoretical calculations, antioxidant, anti-inflammatory, neuroprotective, and brain-blood barrier permeability properties.

PubMed

Chioua, Mourad; Sucunza, David; Soriano, Elena; Hadjipavlou-Litina, Dimitra; Alcázar, Alberto; Ayuso, Irene; Oset-Gasque, María Jesús; González, María Pilar; Monjas, Leticia; Rodríguez-Franco, María Isabel; Marco-Contelles, José; Samadi, Abdelouahid

2012-01-12

We report the synthesis, theoretical calculations, the antioxidant, anti-inflammatory, and neuroprotective properties, and the ability to cross the blood-brain barrier (BBB) of (Z)-α-aryl and heteroaryl-N-alkyl nitrones as potential agents for stroke treatment. The majority of nitrones compete with DMSO for hydroxyl radicals, and most of them are potent lipoxygenase inhibitors. Cell viability-related (MTT assay) studies clearly showed that nitrones 1-3 and 10 give rise to significant neuroprotection. When compounds 1-11 were tested for necrotic cell death (LDH release test) nitrones 1-3, 6, 7, and 9 proved to be neuroprotective agents. In vitro evaluation of the BBB penetration of selected nitrones 1, 2, 10, and 11 using the PAMPA-BBB assay showed that all of them cross the BBB. Permeable quinoline nitrones 2 and 3 show potent combined antioxidant and neuroprotective properties and, therefore, can be considered as new lead compounds for further development in specific tests for potential stroke treatment.

Engineering a self-driven PVDF/PDA hybrid membranes based on membrane micro-reactor effect to achieve super-hydrophilicity, excellent antifouling properties and hemocompatibility

NASA Astrophysics Data System (ADS)

Li, Jian-Hua; Ni, Xing-Xing; Zhang, De-Bin; Zheng, Hui; Wang, Jia-Bin; Zhang, Qi-Qing

2018-06-01

A facile and versatile approach for the preparation of super-hydrophilic, excellent antifouling and hemocompatibility membranes had been developed through the generation in situ of bio-inspired polydopamine (PDA) microspheres on PVDF membranes. SEM images showed that the PDA microspheres were uniformly dispersed on the upper surface and the lower surface of the modified membranes. And there were a great number of PDA microspheres immobilized on the cross-section, but the interconnected pores structure was not destroyed. These facts indicated the existence of membrane micro-reactor effect for the whole membrane structure. Considering the remarkable improvement of hydrophilicity, antifouling properties, and permeation fluxes, we also proposed the cluster phenolic hydroxyl effect for the PVDF/PDA hybrid membranes. And the cluster phenolic hydroxyl effect can be ascribed to the all directions distributed phenolic hydroxyl groups on the whole membrane structure. Besides, the self-driven filtration experiments showed the great wetting ability and permeability of the PVDF/PDA hybrid membranes in filtration process without any external pressure. This implied the existence of accelerating self-driven force after the water flow flowed into the internal of membranes, which contributed to the increase of water flow velocity. All the three aspects were in favor of the enhancement of hydrophilicity, antifouling properties and permeability of the modified membranes. Moreover, the conventional filtration tests, oil/water emulsion filtration tests and protein adsorption tests were also carried out to discuss the practical applications of PVDF/PDA hybrid membranes. And the hemocompatibility of the modified membranes was also proved to enhance greatly through the hemolysis tests and platelet adhesion tests, indicating that the membranes were greatly promising in biomedical applications. The strategy of material modification reported here is substrate-independent and can be extended to other substrate materials, and allows the development of novel functional membranes through secondary treatments.

The development and evaluation of advanced Kevlar sandwich structure for application to rotorcraft airframes

NASA Astrophysics Data System (ADS)

Minguet, Pierre; Llorente, Steven; Fay, Russell

1991-05-01

The results of an evaluation of DuPont Kevlar-based material systems in sandwich structure designed for rotorcraft primary airframe structure are presented in this report. The focus of this work has been to evaluate the durability and compression strength of thin-gage Kevlar sandwich panels and investigate means of improvement. It was found that sandwich panels made with Kevlar 149 fibers can be as strong as Kevlar 49 structures but have reduced compression stiffness properties at typical operating strain levels. Thermal cycling was found to affect permeability but not strength in thin facesheet sandwich structure. Any increased permeability can be prevented with the use of an interleaf or surfacing plies. The surfacing plies investigated also had a beneficial effect on sandwich strength due to their stabilizing effect on the facesheet in compression. Finally, a previously developed model was used to analyze the residual strength of a sandwich panel after impact damage.

Seismic-sequence stratigraphy and geologic structure of the Floridan aquifer system near "Boulder Zone" deep wells in Miami-Dade County, Florida

USGS Publications Warehouse

Cunningham, Kevin J.

2015-01-01

In addition to the preceding seismic-reflection analysis, interpretation of geophysical well log data from four effluent injection wells at the North District “Boulder Zone” Well Field delineated a narrow karst collapse structure beneath the injection facility that extends upward about 900 ft from the top of the Boulder Zone to about 125 ft above the top of the uppermost major permeable zone of the Lower Floridan aquifer. No karst collapse structures were identified in the seismic-reflection profiles acquired near the North District “Boulder Zone” Well Field. However, karst collapse structures at the level of the lowermost major permeable zone of the Lower Floridan aquifer at the South District “Boulder Zone” Well Field are present at three locations, as indicated by seismic-reflection data acquired in the C–1 Canal bordering the south side of the injection facility. Results from the North District “Boulder Zone” Well Field well data indicate that a plausible hydraulic connection between faults and stratiform permeability zones may contribute to the upward transport of effluent, terminating above the base of the deepest U.S. Environmental Protection Agency designated underground source of drinking water at the North District “Boulder Zone” Well Field.

Permeability structure of a highly heterogeneous transgressive-marine complex: Tocito Sandstone, New Mexico

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

Lambert, M.L.; Cole, R.D.

1996-01-01

The Tocito Sandstone Member of the Mancos Shale is an Upper Cretaceous shallow-marine sandstone and mudrock complex deposited along the western margin of the Western Interior seaway. The Tocito is a major hydrocarbon producer in the San Juan Basin (approximately 117 million barrels of oil and 79 billion cubic feet of gas). Because of reservoir heterogeneity, ultimate Tocito oil recovery factors are low, generally between 10 and 20 percent. To enhance understanding of permeability heterogeneity in the Tocito, we have undertaken a detailed surface and subsurface investigation. A total of 2,697 permeability measurements have been made using minipermeameters. Permeability variationmore » within the Tocito is controlled by two principal factors: lithofacies and burial/diagenetic history. Coarser grained and better sorted lithofacies have the highest permeability. The permeability values from outcrop and shallow subsurface cores are dramatically higher than those from deep subsurface cores. This is due to dissolution of grains and calcite cement, and decompaction that preferentially affected the outcrop and shallow subsurface. Correlation lengths for permeability values along horizontal transacts are typically less than 3 m, whereas those for vertical transacts are usually less than 0.6 m. These data suggest that small grid block sizes should be used during reservoir simulations if the investigator wishes to accurately capture the reservoir heterogeneity.« less

Permeability structure of a highly heterogeneous transgressive-marine complex: Tocito Sandstone, New Mexico

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

Lambert, M.L.; Cole, R.D.

1996-12-31

The Tocito Sandstone Member of the Mancos Shale is an Upper Cretaceous shallow-marine sandstone and mudrock complex deposited along the western margin of the Western Interior seaway. The Tocito is a major hydrocarbon producer in the San Juan Basin (approximately 117 million barrels of oil and 79 billion cubic feet of gas). Because of reservoir heterogeneity, ultimate Tocito oil recovery factors are low, generally between 10 and 20 percent. To enhance understanding of permeability heterogeneity in the Tocito, we have undertaken a detailed surface and subsurface investigation. A total of 2,697 permeability measurements have been made using minipermeameters. Permeability variationmore » within the Tocito is controlled by two principal factors: lithofacies and burial/diagenetic history. Coarser grained and better sorted lithofacies have the highest permeability. The permeability values from outcrop and shallow subsurface cores are dramatically higher than those from deep subsurface cores. This is due to dissolution of grains and calcite cement, and decompaction that preferentially affected the outcrop and shallow subsurface. Correlation lengths for permeability values along horizontal transacts are typically less than 3 m, whereas those for vertical transacts are usually less than 0.6 m. These data suggest that small grid block sizes should be used during reservoir simulations if the investigator wishes to accurately capture the reservoir heterogeneity.« less

Polymeric membrane materials: new aspects of empirical approaches to prediction of gas permeability parameters in relation to permanent gases, linear lower hydrocarbons and some toxic gases.

PubMed

Malykh, O V; Golub, A Yu; Teplyakov, V V

2011-05-11

Membrane gas separation technologies (air separation, hydrogen recovery from dehydrogenation processes, etc.) use traditionally the glassy polymer membranes with dominating permeability of "small" gas molecules. For this purposes the membranes based on the low free volume glassy polymers (e.g., polysulfone, tetrabromopolycarbonate and polyimides) are used. On the other hand, an application of membrane methods for VOCs and some toxic gas recovery from air, separation of the lower hydrocarbons containing mixtures (in petrochemistry and oil refining) needs the membranes with preferable penetration of components with relatively larger molecular sizes. In general, this kind of permeability is characterized for rubbers and for the high free volume glassy polymers. Data files accumulated (more than 1500 polymeric materials) represent the region of parameters "inside" of these "boundaries." Two main approaches to the prediction of gas permeability of polymers are considered in this paper: (1) the statistical treatment of published transport parameters of polymers and (2) the prediction using model of ≪diffusion jump≫ with consideration of the key properties of the diffusing molecule and polymeric matrix. In the frames of (1) the paper presents N-dimensional methods of the gas permeability estimation of polymers using the correlations "selectivity/permeability." It is found that the optimal accuracy of prediction is provided at n=4. In the frames of the solution-diffusion mechanism (2) the key properties include the effective molecular cross-section of penetrating species to be responsible for molecular transportation in polymeric matrix and the well known force constant (ε/k)(eff i) of {6-12} potential for gas-gas interaction. Set of corrected effective molecular cross-section of penetrant including noble gases (He, Ne, Ar, Kr, Xe), permanent gases (H(2), O(2), N(2), CO), ballast and toxic gases (CO(2), NO(,) NO(2), SO(2), H(2)S) and linear lower hydrocarbons (CH(4), C(2)H(6), C(3)H(8), C(4)H(10), C(2)H(4), C(3)H(6), C(4)H(8) - 1, C(2)H(2), C(3)H(4)-m (methylacetylene) and C(3)H(4)-a (allen) is determined by using two above mentioned approaches. All of this allows calculating preliminary the permeability parameters of above mentioned gases for most part of known polymers based on limited experimental data. The new correlations suggested demonstrate that the available free volume of polymeric matrix plays an important role in providing of rate and selectivity of gas diffusion for glassy-like polymers; the rate and selectivity of gas diffusion in rubbers is affected mainly by cohesion energy density (CED) the both polymer parameters being calculated by traditional additive group contributions technique. Results of present study are demonstrated by calculation of expected permeability parameters in relation to lower hydrocarbons and some toxic gases for polynorbornene based polymers, PIM and PTMSP outlining potential of practical application for new membrane polymers. Copyright © 2010 Elsevier B.V. All rights reserved.

Oxygen, water, and sodium chloride transport in soft contact lenses materials.

PubMed

Gavara, Rafael; Compañ, Vicente

2017-11-01

Oxygen permeability, diffusion coefficient of the sodium ions and water flux and permeability in different conventional hydrogel (Hy) and silicone-hydrogel (Si-Hy) contact lenses have been measured experimentally. The results showed that oxygen permeability and transmissibility requirements of the lens have been addressed through the use of siloxane containing hydrogels. In general, oxygen and sodium chloride permeability values increased with the water content of the lens but there was a percolation phenomenon from a given value of water uptake mainly in the Si-Hy lenses which appeared to be related with the differences between free water and bound water contents. The increase of ion permeability with water content did not follow a unique trend indicating a possible dependence of the chemical structure of the polymer and character ionic and non-ionic of the lens. Indeed, the salt permeability values for silicone hydrogel contact lenses were one order of magnitude below those of conventional hydrogel contact lenses, which can be explained by a diffusion of sodium ions occurring only through the hydrophilic channels. The increase of the ionic permeability in Si-Hy materials may be due to the confinement of ions in nanoscale water channels involving possible decreased degrees of freedom for diffusion of both water and ions. In general, ionic lenses presented values of ionic permeability and diffusivity higher than most non-ionic lenses. The tortuosity of the ionic lenses is lower than the non-ionic Si-Hy lenses. Frequency 55 and PureVision exhibited the highest water permeability and flux values and, these parameters were greater for ionic Si-Hy lenses than for ionic conventional hydrogel lenses. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 105B: 2218-2231, 2017. © 2016 Wiley Periodicals, Inc.

The Mitochondrial Permeability Transition Pore: Channel Formation by F-ATP Synthase, Integration in Signal Transduction, and Role in Pathophysiology

PubMed Central

Bernardi, Paolo; Rasola, Andrea; Forte, Michael; Lippe, Giovanna

2015-01-01

The mitochondrial permeability transition (PT) is a permeability increase of the inner mitochondrial membrane mediated by a channel, the permeability transition pore (PTP). After a brief historical introduction, we cover the key regulatory features of the PTP and provide a critical assessment of putative protein components that have been tested by genetic analysis. The discovery that under conditions of oxidative stress the F-ATP synthases of mammals, yeast, and Drosophila can be turned into Ca2+-dependent channels, whose electrophysiological properties match those of the corresponding PTPs, opens new perspectives to the field. We discuss structural and functional features of F-ATP synthases that may provide clues to its transition from an energy-conserving into an energy-dissipating device as well as recent advances on signal transduction to the PTP and on its role in cellular pathophysiology. PMID:26269524

Rapid and efficient crossing blood-brain barrier: Hydrophobic drug delivery system based on propionylated amylose helix nanoclusters.

PubMed

Gao, Wei; Liu, Yongchun; Jing, Guixia; Li, Ke; Zhao, Yuan; Sha, Baoyong; Wang, Qiang; Wu, Daocheng

2017-01-01

A novel strategy of rapid transport across the blood-brain barrier (BBB) via phosphatidylethanolamine-triggered release is developed through both molecular dynamics (MD) simulation and experiments. Hydrophobic drugs, namely, propofol, iodine, and 1,1'-dioctadecyltetramethyl indotricarbocyanine iodide, were loaded with propionylated amylose helix (HLPAH) nanoclusters to form PLPAH, ILPAH, and DLPAH nanoclusters, respectively. These clusters were subjected to MD simulation, structure measurement, in vitro triggered study, in vivo DLPAH imaging, and analysis of PLPAH sedative effects on rabbits. Results indicated that HLPAH nanoclusters were initially located on the BBB, and the helix was unfolded to release the loaded hydrophobic drugs. The released drugs crossed the BBB and performed their functions in the central nervous system (CNS) through concentration gradient and hydrophobicity. This mechanism of HLPAH across the BBB featured high membrane permeability and specificity, rapid onset, short maintenance, rapid recovery, and lower dosage of drugs. Hence, this novel strategy is very meaningful for the development of CNS drug carriers and the proposed system could be used to improve the therapeutic effects of CNS diseases. Copyright © 2016 Elsevier Ltd. All rights reserved.

Identification of a residue in helix 2 of rice plasma membrane intrinsic proteins that influences water permeability.

PubMed

Zhang, Minhua; Lü, Shouqin; Li, Guowei; Mao, Zhilei; Yu, Xin; Sun, Weining; Tang, Zhangcheng; Long, Mian; Su, Weiai

2010-12-31

Molecular selection, ion exclusion, and water permeation are well known regulatory mechanisms in aquaporin. Water permeability was found to be diverse in different subgroups of plasma membrane intrinsic proteins (PIPs), even though the residues surrounding the water holes remained the same across the subgroups. Upon homology modeling and structural comparison, a conserved Ala/Ile(Val) residue difference was identified in helix 2 that affected the conformation of the NPA region and consequently influenced the water permeability. The residue difference was found to be conservative within the two subgroups of PIPs in rice as well as in other plants. Functional tests further confirmed the prediction via site-directed mutagenesis where replacement of Ala(103) or Ala(102) in respective OsPIP1;1 or OsPIP1;3 with Val yielded 7.0- and 2.2-fold increases in water transportation, and substitution of Ile(98) or Val(95) in respective OsPIP2;3 or OsPIP2;7 with Ala resulted in 73 or 52% reduction of water transportation. Based on structural analyses and molecular dynamics simulations, we proposed that the difference in water permeability was attributed to the orientation variations of helix 2 that modified water-water and water-protein interactions.

Exploring the segregating and mineralization-inducing capacities of cationic hydrophilic polymers for preparation of robust, multifunctional mesoporous hybrid microcapsules.

PubMed

Shi, Jiafu; Zhang, Wenyan; Wang, Xiaoli; Jiang, Zhongyi; Zhang, Shaohua; Zhang, Xiaoman; Zhang, Chunhong; Song, Xiaokai; Ai, Qinghong

2013-06-12

A facile approach to preparing mesoporous hybrid microcapsules is developed by exploring the segregating and mineralization-inducing capacities of cationic hydrophilic polymer. The preparation process contains four steps: segregation of cationic hydrophilic polymer during template formation, cross-linking of the segregated polymer, biomimetic mineralization within cross-linked polymer network, and removal of template to simultaneously generate capsule lumen and mesopores on the capsule wall. Poly(allylamine hydrochloride) (PAH) is chosen as the model polymer, its hydrophilicity renders the segregating capacity and spontaneous enrichment in the near-surface region of CaCO3 microspheres; its biopolyamine-mimic structure renders the mineralization-inducing capacity to produce titania from the water-soluble titanium(IV) precursor. Meanwhile, CaCO3 microspheres serve the dual templating functions in the formation of hollow lumen and mesoporous wall. The thickness of capsule wall can be controlled by changing the polymer segregating and cross-linking conditions, while the pore size on the capsule wall can be tuned by changing the template synthesizing conditions. The robust hybrid microcapsules exhibit desirable efficiency in enzymatic catalysis, wastewater treatment and drug delivery. This approach may open facile, generic, and efficient pathway to designing and preparing a variety of hybrid microcapsules with high and tunable permeability, good stability and multiple functionalities for a broad range of applications.

POROSITY OF ISOLATED CELL WALLS OF SACCHAROMYCES CEREVISIAE AND BACILLUS MEGATERIUM.

PubMed

GERHARDT, P; JUDGE, J A

1964-04-01

Gerhardt, Philipp (The University of Michigan, Ann Arbor), and Jean A. Judge. Porosity of isolated cell walls of a yeast and a bacillus. J. Bacteriol. 87:945-951. 1964.-Decagram masses of cell walls were isolated from Saccharomyces cerevisiae and Bacillus megaterium; their porosity was examined by measuring the extent of uptake with polyethylene glycols and dextrans varying in molecular weight from 62 to 2,000,000. The results indicated that both walls are heteroporous. The near equality of extrapolated water-uptake values and determined moisture contents suggested that water in the cell walls is mainly free for distribution of solutes. Polymers with molecular weights of 4,500 and above were excluded by the yeast walls, and those with molecular weights of 57,000 were excluded by the bacillus walls; from these results, maximal openings of 36 and 107 A, respectively, were calculated. Electron micrographs of shadowed, stained, and sectioned walls revealed fine structure not inconsistent with heteroporosity, but the predicted openings were not seen. Altogether, in structure and permeability behavior, the cell walls were like a random meshwork of cross-linked macromolecular strands.

One-pot fabrication of graphene oxide-patched hollow-structured microgel particles in a microcapillary device

NASA Astrophysics Data System (ADS)

Byun, Aram; Jeong, Eun Seon; Kim, Jin Woong

2014-03-01

Microgels are colloidal gel particles that consist of chemically cross-linked three-dimensional polymer networks. They play an essential role in delivery and release of active ingredients in medicine, cosmetics, food, and even autonomic self-healing applications. Despite their wide applicability, permeability control through the hydrogel phase is limited due to its intrinsic loose network nature. Herein, we introduce generation of hollow-structured microgel particles whose interfaces were patched with graphene oxide (GO) sheets. The whole fabrication procedure was carried out in a microcapillary device in a single step. GO sheets have an ability to adhere to both O/W and W/O interfaces. Taking advantages of this behavior, we generated monodisperse O/W/O double emulsion whose interfaces were patched with GO sheets. Solidification of the aqueous middle phase to the hydrogel phase gave rise to uniform GO-patched microgel shell particles. Furthermore, we demonstrated that the permeation of molecules through the shell could be controlled even to small molecular length scales due to the adsorption of GO.

Simulation of gas flow in micro-porous media with the regularized lattice Boltzmann method

DOE PAGES

Wang, Junjian; Kang, Qinjun; Wang, Yuzhu; ...

2017-06-01

One primary challenge for prediction of gas flow in the unconventional gas reservoir at the pore-scale such as shale and tight gas reservoirs is the geometric complexity of the micro-porous media. In this paper, a regularized multiple-relaxation-time (MRT) lattice Boltzmann (LB) model is applied to analyze gas flow in 2-dimensional micro-porous medium reconstructed by quartet structure generation set (QSGS) on pore-scale. In this paper, the velocity distribution inside the porous structure is presented and analyzed, and the effects of the porosity and specific surface area on the rarefied gas flow and apparent permeability are examined and investigated. The simulation resultsmore » indicate that the gas exhibits different flow behaviours at various pressure conditions and the gas permeability is strongly related to the pressure. Finally, the increased porosity or the decreased specific surface area leads to the increase of the gas apparent permeability, and the gas flow is more sensitive to the pore morphological properties at low-pressure conditions.« less

Simulation of gas flow in micro-porous media with the regularized lattice Boltzmann method

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

Wang, Junjian; Kang, Qinjun; Wang, Yuzhu

One primary challenge for prediction of gas flow in the unconventional gas reservoir at the pore-scale such as shale and tight gas reservoirs is the geometric complexity of the micro-porous media. In this paper, a regularized multiple-relaxation-time (MRT) lattice Boltzmann (LB) model is applied to analyze gas flow in 2-dimensional micro-porous medium reconstructed by quartet structure generation set (QSGS) on pore-scale. In this paper, the velocity distribution inside the porous structure is presented and analyzed, and the effects of the porosity and specific surface area on the rarefied gas flow and apparent permeability are examined and investigated. The simulation resultsmore » indicate that the gas exhibits different flow behaviours at various pressure conditions and the gas permeability is strongly related to the pressure. Finally, the increased porosity or the decreased specific surface area leads to the increase of the gas apparent permeability, and the gas flow is more sensitive to the pore morphological properties at low-pressure conditions.« less

Micromachined evaporators for AMTEC cells

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

Izenson, M.G.; Crowley, C.J.

1996-12-31

To achieve high cell efficiency and reliability, the capillary pumping system for Alkali Metal Thermal to Electric Conversion (AMTEC) must have three key characteristics: (1) very small pores to achieve a high capillary pumping head, (2) high permeability for the flow of liquid sodium to minimize internal losses, and (3) be made from a material that is exceptionally stable at high temperatures in a sodium environment. The authors have developed micromachining techniques to manufacture high performance evaporators for AMTEC cells. The evaporators have been fabricated from stainless steel, molybdenum, and a niobium alloy (Nb-1Zr). The regular, micromachined structure leads tomore » very high capillary pumping head with high permeability for liquid flow. Data from tests performed with common fluids at room temperature characterize the capillary pumping head and permeability of these structures. Three micromachined evaporators have been built into AMTEC cells and operated at temperatures up to 1,100 K. Results from these tests confirm the excellent pumping capabilities of the micromachined evaporators.« less

Highly predictive and interpretable models for PAMPA permeability.

PubMed

Sun, Hongmao; Nguyen, Kimloan; Kerns, Edward; Yan, Zhengyin; Yu, Kyeong Ri; Shah, Pranav; Jadhav, Ajit; Xu, Xin

2017-02-01

Cell membrane permeability is an important determinant for oral absorption and bioavailability of a drug molecule. An in silico model predicting drug permeability is described, which is built based on a large permeability dataset of 7488 compound entries or 5435 structurally unique molecules measured by the same lab using parallel artificial membrane permeability assay (PAMPA). On the basis of customized molecular descriptors, the support vector regression (SVR) model trained with 4071 compounds with quantitative data is able to predict the remaining 1364 compounds with the qualitative data with an area under the curve of receiver operating characteristic (AUC-ROC) of 0.90. The support vector classification (SVC) model trained with half of the whole dataset comprised of both the quantitative and the qualitative data produced accurate predictions to the remaining data with the AUC-ROC of 0.88. The results suggest that the developed SVR model is highly predictive and provides medicinal chemists a useful in silico tool to facilitate design and synthesis of novel compounds with optimal drug-like properties, and thus accelerate the lead optimization in drug discovery. Copyright © 2016 Elsevier Ltd. All rights reserved.

Structure/permeability relationships of silicon-containing polyimides

NASA Technical Reports Server (NTRS)

Stern, S. A.; Vaidyanathan, R.; Pratt, J. R.

1989-01-01

The permeability to H2, O2, N2, CO2 and CH4 of three silicone-polyimide random copolymers and two polyimides containing silicon atoms in their backbone chains, was determined at 35.0 C and at pressures up to about 120 psig (approximately 8.2 atm). The copolymers contained different amounts of BPADA-m-PDA and amine-terminated poly (dimethyl siloxane) and also had different numbers of siloxane linkages in their silicone component. The polyimides containing silicon atoms (silicon-modified polyimides) were SiDA-4,4'-ODA and SiDA-p-PDA. The gas permeability and selectivity of the copolymers are more similar to those of their silicone component than of the polyimide component. By contrast, the permeability and selectivity of the silicon-modified polyimides are more similar to those of their parent polyimides, PMDA-4,4'-ODA and SiDA-p-PDA. The substitution of SiDA for the PMDA moiety in a polyimide appears to result in a significant increase in gas permeability, without a correspondingly large decrease in selectivity. The potential usefulness of the above polymers and copolymers as gas separation membranes is discussed.

Preparation of Low fouling Polyethersulfone Membranes by Simultaneously Phase Separation and Redox Polymerization

NASA Astrophysics Data System (ADS)

Roihatin, A.; Susanto, H.

2017-05-01

This paper presents preparation of low fouling PES membranes by non solvent induced phase separation (NIPS) coupled with redox polymerization. The membrane characterization included water permeability, morphology structure (by SEM) and surface chemistry (by FTIR). Water permeability measurements showed thatthe membranes have water permeability within the range 10-50 L/h.m2.bar. Addition of PEG dan PEGMA intopolymer solution increased water permeability, whereas blending redox initiator and crosslinker, MBAA in polymer solution decreased water permeability. Surface morfology of membranes by SEM showed that unmodified PES membrane had smaller pore size than PEG or PEGMA modified PES membranes. Furthermore, PES-PEG or PES-PEGMA membranes modified by blending with redox initiator and MBAA as crosslinker showed smaller pore size than unmodified membrane. FTIR analysis showed that all membranes have typical spectraof PES polymer; however no additional peak was observed forthe membranes prepared with addition of PEG/PEGMA, initiator redox and also crosslinker. The addition of PEG/PEGMA, redox initiator and crosslinker resulted in membranes with high rejection and an acceptable flux as well as more stable due to relatively high fouling resistance.

Field determination of vertical permeability to air in the unsaturated zone

USGS Publications Warehouse

Weeks, Edwin P.

1978-01-01

The vertical permeability to air of layered materials in the unsaturated zone may be determined from air pressure data obtained at depth during a period when air pressure is changing at land surface. Such data may be obtained by monitoring barometric pressure with a microbarograph or surveying altimeter and simultaneously measuring down-hole pneumatic head differences in specially constructed piezometers. These data, coupled with air-filled porosity data from other sources, may be compared with the results of electric-analog or numerical solution of the one-dimensional diffusion equation to make a trial-and-error determination of the air permeability for each layer. The permeabilities to air may in turn be converted to equivalent hydraulic conductivity values if the materials are well drained, are permeable enough that the Klinkenberg effect is small, and are structurally unaffected by wetting. The method offers potential advantages over present methods to evaluate sites for artificial recharge by spreading; to evaluate ground-water pollution hazards from feedlots, sanitary landfills , and land irrigated with sewage effluent; and to evaluate sites for temporary storage of gas in the unsaturated zone. (Woodard-USGS)

Surface nano-structure of polyamide 6 film by hydrothermal treatment

NASA Astrophysics Data System (ADS)

Wang, Xiaosong; Wang, Zhiliang; Liang, Songmiao; Jin, Yan; Lotz, Bernard; Yang, Shuguang

2018-06-01

Polyamide 6 (PA 6) melts and dissolves in super-heated water when T > 160 °C. Commercial PA 6 films were treated in super-heated water at 140 °C < T < 160 °C, i.e. below melting. Morphology, thermal behavior, mechanical properties, oxygen permeability and transparency of the film before and after hydrothermal treatment are investigated. After hydrothermal treatment, the melting temperature, crystallinity, elongation at break and toughness increase, whereas the strength decreases. The transparency and oxygen permeability decrease slightly. More interestingly, the hydrothermal treatment generates on the film surface a nano-structured layer 100 nm thick, which greatly improves adhesion and printing performance.

High frequency permeability of Fe-Cu-Nb-Si-B nanocrystalline flakes with the distribution of shape anisotropy fields

NASA Astrophysics Data System (ADS)

Luo, Xing; Wu, Yanhui; Han, Mangui; Deng, Longjiang

2018-04-01

Fe-Cu-Nb-Si-B flakes with multiphase nanostructures have been obtained by annealing the amorphous ribbon and subsequently ball milled for 30 h. The crystal structures have been examined by X-ray diffraction pattern and Mössbauer spectrum. The results show that the particles annealed at 900 °C are made up of amorphous ferromagnetic phase, α-Fe3Si ferromagnetic phase and Fe2B phase, and the average hyperfine magnetic field (HBhf) of particles is 24.02 T. Meanwhile, the relationships between the structure and the high frequency permeability have been studied. Compared with particles annealed at 600 °C, particles annealed at 900 °C exhibit higher saturation magnetization, which is evidenced by the larger HBhf. Also, three magnetic loss peaks in a permeability spectrum have been observed for the particles annealed at 900 °C. The natural resonance frequencies are calculated, which are in good agreement with the experimental resonance peaks. The origin of the multiple magnetic loss peaks can be explained from the perspective of the distribution of shape anisotropy fields which is caused by multiple phase structure.

An integrated simulator of structure and anisotropic flow in gas diffusion layers with hydrophobic additives

NASA Astrophysics Data System (ADS)

Burganos, Vasilis N.; Skouras, Eugene D.; Kalarakis, Alexandros N.

2017-10-01

The lattice-Boltzmann (LB) method is used in this work to reproduce the controlled addition of binder and hydrophobicity-promoting agents, like polytetrafluoroethylene (PTFE), into gas diffusion layers (GDLs) and to predict flow permeabilities in the through- and in-plane directions. The present simulator manages to reproduce spreading of binder and hydrophobic additives, sequentially, into the neat fibrous layer using a two-phase flow model. Gas flow simulation is achieved by the same code, sidestepping the need for a post-processing flow code and avoiding the usual input/output and data interface problems that arise in other techniques. Compression effects on flow anisotropy of the impregnated GDL are also studied. The permeability predictions for different compression levels and for different binder or PTFE loadings are found to compare well with experimental data for commercial GDL products and with computational fluid dynamics (CFD) predictions. Alternatively, the PTFE-impregnated structure is reproduced from Scanning Electron Microscopy (SEM) images using an independent, purely geometrical approach. A comparison of the two approaches is made regarding their adequacy to reproduce correctly the main structural features of the GDL and to predict anisotropic flow permeabilities at different volume fractions of binder and hydrophobic additives.

Arsenite induces endothelial cell permeability increase through a reactive oxygen species-vascular endothelial growth factor pathway.

PubMed

Bao, Lingzhi; Shi, Honglian

2010-11-15

As a potent environmental oxidative stressor, arsenic exposure has been reported to exacerbate cardiovascular diseases and increase vascular endothelial cell monolayer permeability. However, the underlying mechanism of this effect is not well understood. In this paper, we test our hypothesis that reactive oxygen species (ROS)-induced vascular endothelial growth factor (VEGF) expression may play an important role in an arsenic-caused increase of endothelial cell monolayer permeability. The mouse brain vascular endothelial cell bEnd3 monolayer was exposed to arsenite for 1, 3, and 6 days. The monolayer permeability, VEGF protein release, and ROS generation were determined. In addition, VE-cadherin and zonula occludens-1 (ZO-1), two membrane structure proteins, were immunostained to elucidate the effects of arsenite on the cell-cell junction. The roles of ROS and VEGF in arsenite-induced permeability was determined by inhibiting ROS with antioxidants and immuno-depleting VEGF with a VEGF antibody. We observed that arsenite increased bEnd3 monolayer permeability, elevated the production of cellular ROS, and increased VEGF release. VE-cadherin and ZO-1 disruptions were also found in cells treated with arsenite. Furthermore, both antioxidant (N-acetyl cysteine and tempol) and the VEGF antibody treatments significantly lowered the arsenite-induced permeability of the bEnd3 monolayer as well as VEGF expression. VE-cadherin and ZO-1 disruptions were also diminished by N-acetyl cysteine and the VEGF antibody. Our data suggest that the increase in VEGF expression caused by ROS may play an important role in the arsenite-induced increase in endothelial cell permeability.

Parameterization and Modeling of Coupled Heat and Mass Transport in the Vadose Zone

NASA Astrophysics Data System (ADS)

Mohanty, B.; Yang, Z.

2016-12-01

The coupled heat and mass transport in the vadose zone is essentially a multiphysics issue. Addressing this issue appropriately has remarkable impacts on soil physical, chemical and biological processes. To data, most coupled heat and water transport modeling has focused on the interactions between liquid water, water vapor and heat transport in homogeneous and layered soils. Comparatively little work has been done on structured soils where preferential infiltration and evaporation flow occurs. Moreover, the traditional coupled heat and water model usually neglects the nonwetting phase air flow, which was found to be significant in the state-of-the-art modeling framework for coupled heat and water transport investigation. However, the parameterizations for the nonwetting phase air permeability largely remain elusive so far. In order to address the above mentioned limitations, this study aims to develop and validate a predictive multiphysics modeling framework for coupled soil heat and water transport in the heterogeneous shallow subsurface. To this end, the following research work is specifically conducted: (a) propose an improved parameterization to better predict the nonwetting phase relative permeability; (b) determine the dynamics, characteristics and processes of simultaneous soil moisture and heat movement in homogeneous and layered soils; and (c) develop a nonisothermal dual permeability model for heterogeneous structured soils. The results of our studies showed that: (a) the proposed modified nonwetting phase relative permeability models are much more accurate, which can be adopted for better parameterization in the subsequent nonisothermal two phase flow models; (b) the isothermal liquid film flow, nonwetting phase gas flow and liquid-vapor phase change non-equilibrium effects are significant in the arid and semiarid environments (Riverside, California and Audubon, Arizona); and (c) the developed nonisothermal dual permeability model is capable of characterizing the preferential evaporation path in the heterogeneous structured soils due to the fact that the capillary forces divert the pore water from coarse-textured soils (high temperature region) toward the fine-textured soils (low temperature region).

Parts-based geophysical inversion with application to water flooding interface detection and geological facies detection

NASA Astrophysics Data System (ADS)

Zhang, Junwei

I built parts-based and manifold based mathematical learning model for the geophysical inverse problem and I applied this approach to two problems. One is related to the detection of the oil-water encroachment front during the water flooding of an oil reservoir. In this application, I propose a new 4D inversion approach based on the Gauss-Newton approach to invert time-lapse cross-well resistance data. The goal of this study is to image the position of the oil-water encroachment front in a heterogeneous clayey sand reservoir. This approach is based on explicitly connecting the change of resistivity to the petrophysical properties controlling the position of the front (porosity and permeability) and to the saturation of the water phase through a petrophysical resistivity model accounting for bulk and surface conductivity contributions and saturation. The distributions of the permeability and porosity are also inverted using the time-lapse resistivity data in order to better reconstruct the position of the oil water encroachment front. In our synthetic test case, we get a better position of the front with the by-products of porosity and permeability inferences near the flow trajectory and close to the wells. The numerical simulations show that the position of the front is recovered well but the distribution of the recovered porosity and permeability is only fair. A comparison with a commercial code based on a classical Gauss-Newton approach with no information provided by the two-phase flow model fails to recover the position of the front. The new approach could be also used for the time-lapse monitoring of various processes in both geothermal fields and oil and gas reservoirs using a combination of geophysical methods. A paper has been published in Geophysical Journal International on this topic and I am the first author of this paper. The second application is related to the detection of geological facies boundaries and their deforation to satisfy to geophysica data and prior distributions. We pose the geophysical inverse problem in terms of Gaussian random fields with mean functions controlled by petrophysical relationships and covariance functions controlled by a prior geological cross-section, including the definition of spatial boundaries for the geological facies. The petrophysical relationship problem is formulated as a regression problem upon each facies. The inversion is performed in a Bayesian framework. We demonstrate the usefulness of this strategy using a first synthetic case study, performing a joint inversion of gravity and galvanometric resistivity data with the stations all located at the ground surface. The joint inversion is used to recover the density and resistivity distributions of the subsurface. In a second step, we consider the possibility that the facies boundaries are deformable and their shapes are inverted as well. We use the level set approach to deform the facies boundaries preserving prior topological properties of the facies throughout the inversion. With the additional help of prior facies petrophysical relationships, topological characteristic of each facies, we make posterior inference about multiple geophysical tomograms based on their corresponding geophysical data misfits. The result of the inversion technique is encouraging when applied to a second synthetic case study, showing that we can recover the heterogeneities inside the facies, the mean values for the petrophysical properties, and, to some extent, the facies boundaries. A paper has been submitted to Geophysics on this topic and I am the first author of this paper. During this thesis, I also worked on the time lapse inversion problem of gravity data in collaboration with Marios Karaoulis and a paper was published in Geophysical Journal international on this topic. I also worked on the time-lapse inversion of cross-well geophysical data (seismic and resistivity) using both a structural approach named the cross-gradient approach and a petrophysical approach. A paper was published in Geophysics on this topic.

Permeability of the blood-brain barrier predicts conversion from optic neuritis to multiple sclerosis.

PubMed

Cramer, Stig P; Modvig, Signe; Simonsen, Helle J; Frederiksen, Jette L; Larsson, Henrik B W

2015-09-01

Optic neuritis is an acute inflammatory condition that is highly associated with multiple sclerosis. Currently, the best predictor of future development of multiple sclerosis is the number of T2 lesions visualized by magnetic resonance imaging. Previous research has found abnormalities in the permeability of the blood-brain barrier in normal-appearing white matter of patients with multiple sclerosis and here, for the first time, we present a study on the capability of blood-brain barrier permeability in predicting conversion from optic neuritis to multiple sclerosis and a direct comparison with cerebrospinal fluid markers of inflammation, cellular trafficking and blood-brain barrier breakdown. To this end, we applied dynamic contrast-enhanced magnetic resonance imaging at 3 T to measure blood-brain barrier permeability in 39 patients with monosymptomatic optic neuritis, all referred for imaging as part of the diagnostic work-up at time of diagnosis. Eighteen healthy controls were included for comparison. Patients had magnetic resonance imaging and lumbar puncture performed within 4 weeks of onset of optic neuritis. Information on multiple sclerosis conversion was acquired from hospital records 2 years after optic neuritis onset. Logistic regression analysis showed that baseline permeability in normal-appearing white matter significantly improved prediction of multiple sclerosis conversion (according to the 2010 revised McDonald diagnostic criteria) within 2 years compared to T2 lesion count alone. There was no correlation between permeability and T2 lesion count. An increase in permeability in normal-appearing white matter of 0.1 ml/100 g/min increased the risk of multiple sclerosis 8.5 times whereas having more than nine T2 lesions increased the risk 52.6 times. Receiver operating characteristic curve analysis of permeability in normal-appearing white matter gave a cut-off of 0.13 ml/100 g/min, which predicted conversion to multiple sclerosis with a sensitivity of 88% and specificity of 72%. We found a significant correlation between permeability and the leucocyte count in cerebrospinal fluid as well as levels of CXCL10 and MMP9 in the cerebrospinal fluid. These findings suggest that blood-brain barrier permeability, as measured by magnetic resonance imaging, may provide novel pathological information as a marker of neuroinflammation related to multiple sclerosis, to some extent reflecting cellular permeability of the blood-brain barrier, whereas T2 lesion count may more reflect the length of the subclinical pre-relapse phase.See Naismith and Cross (doi:10.1093/brain/awv196) for a scientific commentary on this article. © The Author (2015). Published by Oxford University Press on behalf of the Guarantors of Brain.

Nano-iron Tracer Test for Characterizing Preferential Flow Path in Fractured Rock

NASA Astrophysics Data System (ADS)

Chia, Y.; Chuang, P. Y.

2015-12-01

Deterministic description of the discrete features interpreted from site characterization is desirable for developing a discrete fracture network conceptual model. It is often difficult, however, to delineate preferential flow path through a network of discrete fractures in the field. A preliminary cross-borehole nano-iron tracer test was conducted to characterize the preferential flow path in fractured shale bedrock at a hydrogeological research station. Prior to the test, heat-pulse flowmeter measurements were performed to detect permeable fracture zones at both the injection well and the observation well. While a few fracture zones are found permeable, most are not really permeable. Chemical reduction method was used to synthesize nano zero-valent iron particles with a diameter of 50~150 nm. The conductivity of nano-iron solution is about 3100 μs/cm. The recorded fluid conductivity shows the arrival of nano-iron solution in the observation well 11.5 minutes after it was released from the injection well. The magnetism of zero-valent iron enables it to be absorbed on magnet array designed to locate the depth of incoming tracer. We found nearly all of absorbed iron on the magnet array in the observation well were distributed near the most permeable fracture zone. The test results revealed a preferential flow path through a permeable fracture zone between the injection well and the observation well. The estimated hydraulic conductivity of the connected fracture is 2.2 × 10-3 m/s. This preliminary study indicated that nano-iron tracer test has the potential to characterize preferential flow path in fractured rock.

Statistical Estimation of Heterogeneities: A New Frontier in Well Testing

NASA Astrophysics Data System (ADS)

Neuman, S. P.; Guadagnini, A.; Illman, W. A.; Riva, M.; Vesselinov, V. V.

2001-12-01

Well-testing methods have traditionally relied on analytical solutions of groundwater flow equations in relatively simple domains, consisting of one or at most a few units having uniform hydraulic properties. Recently, attention has been shifting toward methods and solutions that would allow one to characterize subsurface heterogeneities in greater detail. On one hand, geostatistical inverse methods are being used to assess the spatial variability of parameters, such as permeability and porosity, on the basis of multiple cross-hole pressure interference tests. On the other hand, analytical solutions are being developed to describe the mean and variance (first and second statistical moments) of flow to a well in a randomly heterogeneous medium. Geostatistical inverse interpretation of cross-hole tests yields a smoothed but detailed "tomographic" image of how parameters actually vary in three-dimensional space, together with corresponding measures of estimation uncertainty. Moment solutions may soon allow one to interpret well tests in terms of statistical parameters such as the mean and variance of log permeability, its spatial autocorrelation and statistical anisotropy. The idea of geostatistical cross-hole tomography is illustrated through pneumatic injection tests conducted in unsaturated fractured tuff at the Apache Leap Research Site near Superior, Arizona. The idea of using moment equations to interpret well-tests statistically is illustrated through a recently developed three-dimensional solution for steady state flow to a well in a bounded, randomly heterogeneous, statistically anisotropic aquifer.

Fluvial sandstone reservoirs of Travis Peak (Hosston) Formation, east Texas basin

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

Tye, R.S.

1989-03-01

Gas production (7.2 billion ft/sup 3/) from low-permeability sandstones in the Travis Peak Formation, North Appleby field, Nacogdoches County, Texas, is enhanced through massive hydraulic fracturing of stacked sandstones that occur at depths between 8000 and 10,000 ft. stratigraphic reservoirs were formed in multilateral tabular sandstones owing to impermeable mudstone interbeds that encase blocky to upward-fining sandstones. Pervasive quartz cement in the sandstones decreases porosity and permeability and augments the reservoir seal. Subsurface data indicate that much of this 2000-ft thick section represents aggradation of alluvial-valley deposits. Multiple channel belts form a network of overlapping, broad, tabular sandstones having thickness-to-widthmore » ratios of 1:850 (8-44 ft thick; widths exceed 4-5 mi). Six to eight channel belts, each containing 80-90% medium to fine-grained sandstone, can occupy a 200-ft thick interval. In a vertical sequence through one channel belt sandstone, basal planar cross-bedding grades upward into thinly interbedded sets of planar cross-beds and ripple cross-lamination. Clay-clast conglomerates line scoured channel bases. Adjacent to the channels, interbedded mudstones accumulated in well-drained swamps and lakes. Poorly sorted sandstones represent overbank deposition (crevasse splays and lacustrine deltas). During Travis Peak deposition, fluvial styles evolved from dominantly braided systems near the base of the formation to more mud-rich, meandering systems at the top.« less

Compaction and gas loss in welded pyroclastic deposits as revealed by porosity, permeability, and electrical conductivity measurements of the Shevlin Park Tuff

USGS Publications Warehouse

Wright, Heather M.; Cashman, Katharine V.

2014-01-01

Pyroclastic flows produced by large volcanic eruptions commonly densify after emplacement. Processes of gas escape, compaction, and welding in pyroclastic-flow deposits are controlled by the physical and thermal properties of constituent material. Through measurements of matrix porosity, permeability, and electrical conductivity, we provide a framework for understanding the evolution of pore structure during these processes. Using data from the Shevlin Park Tuff in central Oregon, United States, and from the literature, we find that over a porosity range of 0%–70%, matrix permeability varies by almost 10 orders of magnitude (from 10–20 to 10–11 m2), with over three orders of magnitude variation at any given porosity. Part of the variation at a given porosity is due to permeability anisotropy, where oriented core samples indicate higher permeabilities parallel to foliation (horizontally) than perpendicular to foliation (vertically). This suggests that pore space is flattened during compaction, creating anisotropic crack-like networks, a geometry that is supported by electrical conductivity measurements. We find that the power law equation: k1 = 1.3 × 10–21 × ϕ5.2 provides the best approximation of dominant horizontal gas loss, where k1 = permeability, and ϕ = porosity. Application of Kozeny-Carman fluid-flow approximations suggests that permeability in the Shevlin Park Tuff is controlled by crack- or disk-like pore apertures with minimum widths of 0.3 and 7.5 μm. We find that matrix permeability limits compaction over short times, but deformation is then controlled by competition among cooling, compaction, water resorption, and permeable gas escape. These competing processes control the potential for development of overpressure (and secondary explosions) and the degree of welding in the deposit, processes that are applicable to viscous densification of volcanic deposits in general. Further, the general relationships among porosity, permeability, and pore geometry are relevant for flow of any fluid through an ignimbritic host.

Evaluation of Porosity and Permeability for an Oil Prospect, Offshore Vietnam by using Artificial Neural Networks

NASA Astrophysics Data System (ADS)

Bui, H. T.; Ho, L. T.; Ushijima, K.; Nur, A.

2006-12-01

Determination of porosity and permeability plays a key role either in characterization of a reservoir or in development of an oil field. Their distribution helps to predict the major faults or fractured zones that are related to high porosity area in order to reduce drilling hazards. Porosity and permeability of the rock can be determined directly from the core sample or obtained from well log data such as: sonic, density, neutron or resistivity. These input parameters depend not only on porosity (?) but also on the rock matrix, fluids contained in the rocks, clay mineral component, or geometry of pore structures. Therefore, it is not easy to estimate exactly porosity and permeability since having corrected those values by conventional well log interpretation method. In this study, the Artificial Neural Networks (ANNs) have been used to derive porosity and permeability directly from well log data for Vung Dong oil prospect, southern offshore Vietnam. Firstly, we designed a training patterns for ANNs from neutron porosity, bulk density, P-sonic, deep resistivity, shallow resistivity and MSFL log curves. Then, ANNs were trained by core samples data for porosity and permeability. Several ANNs paradigms have been tried on a basis of trial and error. The batch back- propagation algorithm was found more proficient in training porosity network meanwhile the quick propagation algorithm is more effective in the permeability network. Secondly, trained ANNs was tested and applied for real data set of some wells to calculate and reveal the distribution maps of porosity or permeability. Distributions of porosity and permeability have been correlated with seismic data interpretation to map the faults and fractured zones in the study. The ANNs showed good results of porosity and permeability distribution with high reliability, fast, accurate and low cost features. Therefore, the ANNs should be widely applied in oil and gas industry.

Using environmental features to model highway crossing behavior of Canada lynx in the Southern Rocky Mountains

Treesearch

Phillip E. Baigas; John R. Squires; Lucretia E. Olson; Jacob S. Ivan; Elizabeth. K. Roberts

2017-01-01

Carnivores are particularly sensitive to reductions in population connectivity caused by human disturbance and habitat fragmentation. Permeability of transportation corridors to carnivore movements is central to species conservation given the large spatial extent of transportation networks and the high mobility of many carnivore species. We investigated the degree to...

Modeling the formation of porphyry-copper ores

USGS Publications Warehouse

Ingebritsen, Steven E.

2012-01-01

Porphyry-copper ore systems, the source of much of the world's copper and molybdenum, form when metal-bearing fluids are expelled from shallow, degassing magmas. On page 1613 of this issue, Weis et al. (1) demonstrate that self-organizing processes focus metal deposition. Specifically, their simulation studies indicate that ores develop as consequences of dynamic variations in rock permeability driven by injection of volatile species from rising magmas. Scenarios with a static permeability structure could not reproduce key field observations, whereas dynamic permeability responses to magmatic-fluid injection localized a metal-precipitation front where enrichment by a factor of 103 could be achieved [for an overview of their numerical-simulation model CSMP++, see (2)].

Modeling the Relationship Between Porosity and Permeability During Oxidation of Ablative Materials

NASA Technical Reports Server (NTRS)

Thornton, John M.; Panerai, Francesco; Ferguson, Joseph C.; Borner, Arnaud; Mansour, Nagi N.

2017-01-01

The ablative materials used in thermal protection systems (TPS) undergo oxidation during atmospheric entry which leads to an in-depth change in both permeability and porosity. These properties have a significant affect on heat transfer in a TPS during entry. X-ray micro-tomography has provided 3D images capturing the micro-structure of TPS materials. In this study, we use micro-tomography based simulations to create high-fidelity models relating permeability to porosity during oxidation of FiberForm, the carbon fiber preform of the Phenolic Impregnated Carbon Ablator (PICA) often used as a TPS material. The goal of this study is to inform full-scale models and reduce uncertainty in TPS modeling.

Ultrasound-enhanced delivery of antibiotics and anti-inflammatory drugs into the eye.

PubMed

Nabili, Marjan; Patel, Hetal; Mahesh, Sankaranarayana P; Liu, Ji; Geist, Craig; Zderic, Vesna

2013-04-01

Delivery of sufficient amounts of therapeutic drugs into the eye is often a challenging task. In this study, ultrasound application (frequencies of 400 KHz to 1 MHz, intensities of 0.3-1.0 W/cm(2) and exposure duration of 5 min) was investigated to overcome the barrier properties of cornea, which is a typical route for topical administration of ophthalmic drugs. Permeability of ophthalmic drugs, tobramycin and dexamethasone and sodium fluorescein, a drug-mimicking compound, was studied in ultrasound- and sham-treated rabbit corneas in vitro using a standard diffusion cell setup. Light microscopy observations were used to determine ultrasound-induced structural changes in the cornea. For tobramycin, an increase in permeability for ultrasound- and sham-treated corneas was not statistically significant. Increase of 46%-126% and 32%-109% in corneal permeability was observed for sodium fluorescein and dexamethasone, respectively, with statistical significance (p < 0.05) achieved at all treatment parameter combinations (compared with sham treatments) except for 1-MHz ultrasound applications for dexamethasone experiments. This permeability increase was highest at 400 kHz and appeared to be higher at higher intensities applied. Histologic analysis showed structural changes that were limited to epithelial layers of cornea. In summary, ultrasound application provided enhancement of drug delivery, increasing the permeability of the cornea for the anti-inflammatory ocular drug dexamethasone. Future investigations are needed to determine the effectiveness and safety of this application in in vivo long-term survival studies. Copyright © 2013 World Federation for Ultrasound in Medicine & Biology. Published by Elsevier Inc. All rights reserved.

Microbial mineral illization of montmorillonite in low-permeability oil reservoirs for microbial enhanced oil recovery.

PubMed

Cui, Kai; Sun, Shanshan; Xiao, Meng; Liu, Tongjing; Xu, Quanshu; Dong, Honghong; Wang, Di; Gong, Yejing; Sha, Te; Hou, Jirui; Zhang, Zhongzhi; Fu, Pengcheng

2018-05-11

Microbial mineral illization has been investigated for its role in the extraction and recovery of metals from ores. Here we report our application of mineral bioillization for the microbial enhanced oil recovery in low-permeability oil reservoirs. It aimed to reveal the etching mechanism of the four Fe (III)-reducing microbial strains under anaerobic growth conditions on the Ca-montmorillonite. The mineralogical characterization of the Ca-montmorillonite was performed by Fourier transform infrared spectroscopy, X-ray powder diffraction, scanning electron microscopy and energy dispersive spectrometer. Results showed that the microbial strains could efficiently reduce Fe (III) at an optimal rate of 71 %, and alter the crystal lattice structure of the lamella to promote the interlayer cation exchange, and to efficiently inhibit the Ca-montmorillonite swelling at an inhibitory rate of 48.9 %. Importance Microbial mineral illization is ubiquitous in the natural environment. Microbes in low-permeability reservoirs are able to enable the alteration of the structure and phase of the Fe-poor minerals by reducing Fe (III) and inhibiting clay swelling which is still poorly studied. This study aimed to reveal the interaction mechanism between Fe (III)-reducing bacterial strains and Ca-montmorillonite under anaerobic atmosphere, and to investigate the extent and rates of Fe (III) reduction and phase changes with their activities. Application of Fe (III)-reducing bacteria will provide a new way to inhibit clay swelling, to elevate reservoir permeability, and to reduce pore throat resistance after water flooding for enhanced oil recovery in low-permeability reservoirs. Copyright © 2018 American Society for Microbiology.

Permeability of acetic acid across gel and liquid-crystalline lipid bilayers conforms to free-surface-area theory.

PubMed Central

Xiang, T X; Anderson, B D

1997-01-01

Solubility-diffusion theory, which treats the lipid bilayer membrane as a bulk lipid solvent into which permeants must partition and diffuse across, fails to account for the effects of lipid bilayer chain order on the permeability coefficient of any given permeant. This study addresses the scaling factor that must be applied to predictions from solubility-diffusion theory to correct for chain ordering. The effects of bilayer chemical composition, temperature, and phase structure on the permeability coefficient (Pm) of acetic acid were investigated in large unilamellar vesicles by a combined method of NMR line broadening and dynamic light scattering. Permeability values were obtained in distearoylphosphatidylcholine, dipalmitoylphosphatidylcholine, dimyristoylphosphatidylcholine, and dilauroylphosphatidylcholine bilayers, and their mixtures with cholesterol, at various temperatures both above and below the gel-->liquid-crystalline phase transition temperatures (Tm). A new scaling factor, the permeability decrement f, is introduced to account for the decrease in permeability coefficient from that predicted by solubility-diffusion theory owing to chain ordering in lipid bilayers. Values of f were obtained by division of the observed Pm by the permeability coefficient predicted from a bulk solubility-diffusion model. In liquid-crystalline phases, a strong correlation (r = 0.94) between f and the normalized surface density sigma was obtained: in f = 5.3 - 10.6 sigma. Activation energies (Ea) for the permeability of acetic acid decreased with decreasing phospholipid chain length and correlated with the sensitivity of chain ordering to temperature, [symbol: see text] sigma/[symbol: see text](1/T), as chain length was varied. Pm values decreased abruptly at temperatures below the main phase transition temperatures in pure dipalmitoylphosphatidylcholine and dimyristoylphosphatidylcholine bilayers (30-60-fold) and below the pretransition in dipalmitoylphosphatidylcholine bilayers (8-fold), and the linear relationship between in f and sigma established for liquid-crystalline bilayers was no longer followed. However, in both gel and liquid-crystalline phases in f was found to exhibit an inverse correlation with free surface area (in f = -0.31 - 29.1/af, where af is the average free area (in square angstroms) per lipid molecule). Thus, the lipid bilayer permeability of acetic acid can be predicted from the relevant chain-packing properties in the bilayer (free surface area), regardless of whether chain ordering is varied by changes in temperature, lipid chain length, cholesterol concentration, or bilayer phase structure, provided that temperature effects on permeant dehydration and diffusion and the chain-length effects on bilayer barrier thickness are properly taken into account. PMID:8994607

Distribution of effluent injected into the Boulder Zone of the Floridan aquifer system at the North District Wastewater Treatment Plant, southeastern Florida, 1997–2011

USGS Publications Warehouse

King, Jeffrey N.; Decker, Jeremy D.

2018-02-09

Nonhazardous, secondarily treated, domestic wastewater (effluent) has been injected about 1 kilometer below land surface into the Boulder Zone of the Floridan aquifer system at the North District Wastewater Treatment Plant in southeastern Florida. The Boulder Zone contains saline, nonpotable water. Effluent transport out of the injection zone is a risk of underground effluent injection. At the North District Wastewater Treatment Plant, injected effluent was detected outside the Boulder Zone. The U.S. Geological Survey, in cooperation with Miami-Dade Water and Sewer Department, investigated effluent transport from the Boulder Zone to overlying permeable zones in the Floridan aquifer system.One conceptual model is presented to explain the presence of effluent outside of the injection zone in which effluent injected into the Boulder Zone was transported to the Avon Park permeable zone, forced by buoyancy and injection pressure. In this conceptual model, effluent injected primarily into the Boulder Zone reaches a naturally occurring feature (a karst-collapse structure) near an injection well, through which the effluent is transported vertically upward to the uppermost major permeable zone of the Lower Floridan aquifer. The effluent is then transported laterally through the uppermost major permeable zone of the Lower Floridan aquifer to another naturally occurring feature northwest of the North District Wastewater Treatment Plant, through which it is then transported vertically upward into the Avon Park permeable zone. In addition, a leak within a monitoring well, between monitoring zones, allowed interflow between the Avon Park permeable zone and the Upper Floridan aquifer. A groundwater flow and effluent transport simulation of the hydrogeologic system at the North District Wastewater Treatment Plant, based on the hypothesized and non-unique conceptualization of the subsurface hydrogeology and flow system, generally replicated measured effluent constituent concentration trends. The model was calibrated to match observed concentration trends for total ammonium (NH4+) and total dissolved solids.The investigation qualitatively indicates that fractures, karst-collapse structures, faults, or other hydrogeologic features may permit effluent injected into the Boulder Zone to be transported to overlying permeable zones in the Floridan aquifer system. These findings, however, are qualitative because the locations of transport pathways that might exist from the Boulder Zone to the Avon Park permeable zone are largely unknown.

A New Model for Gas Transfer and Storage in a Permeable Volcanic Edifice

NASA Astrophysics Data System (ADS)

Collinson, A. D.; Neuberg, J.

2011-12-01

There is a marked contrast between the behaviour of a volcano in an open system compared to one which is closed. It is therefore essential to understand degassing, to appreciate how much gas is lost and where. Previous studies by a variety of scientists have led to the accumulation of data via field evidence from both active and fossil volcanoes (Stasiuk et al., 1996), laboratory experiments (Moore et al., 1994) and conceptual modelling, in which Darcy's law has become increasingly applicable (Eichelberger et al., 1986; Edmonds et al., 2003). Of particular interest for this study, is the effect different permeabilities have on the degree and pattern of the gas flux. A new method has been devised to investigate gas transport and storage in a permeable volcanic edifice. The continuity equation and Darcy's law are amalgamated to derive a partial differential equation which is solved using a finite element method to obtain the gas pressure. The associated pressure gradient is then used within Darcy's law to calculate the gas flux. The properties of the gas are described by the ideal gas law. The strength of this method is that it allows the modelling of two and three dimensional structures both in stationary equilibrium and as a time dependent progression. A geometry is created and the pressure and permeabilites incorporated into the model as boundary and domain conditions respectively. The aim of the model is to investigate how variable permeability and pressure gradients influence the gas flux, for example highly permeable cracks in the dome, or impermeable layers within the volcanic structure. We also use this gas model to complement the model of Neuberg et al. (2006) in which brittle failure of the conduit-wall boundary is used as a trigger mechanism of low-frequency earthquakes. The associated behaviour of the gas in response to the brittle failure is simulated in our model by increasing the permeability through a narrow zone at the boundary between the conduit and country rock. In addition, we investigate how the presence of gas and variations in permeability influence the rate and degree of deformation seen in the volcanic edifice. Our model is highly versatile and has the potential to be integral to the understanding of gas transport and storage within a permeable volcanic edifice.

Permeability anisotropy in marine mudstones in the Nankai Trough, SW Japan: Implications for hypothesized lateral fluid flow and chemical transport outboard of the trench

NASA Astrophysics Data System (ADS)

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

2008-12-01

Characterizing dewatering pathways and chemical fluxes near and outboard of subduction trenches is important toward understanding early sediment dewatering and devolatilization. Quantifying fluid flow rates also constrains the hydraulic gradients driving flow, and thus ultimately hold implications for pore pressure distribution and fault mechanical strength. We focus on the well-studied Nankai Trough offshore SW Japan, where drilling has sampled the sedimentary section at several boreholes from ~11 km outboard of the trench to 3 km landward. At these drillsites, &δ37Cl data and correlation of distinct extrema in downhole chloride profiles have been interpreted to reflect substantial horizontal fluid flow to >10 km outboard of the trench within the ~400 m-thick, homogeneous Lower Shikoku Basin (LSB) facies mudstone. The estimated horizontal velocities are 13 ± 5 cm yr-1; the flow is presumably driven by loading during subduction, and mediated by either permeable conduits or strong anisotropy in permeability. However, the pressure gradients and sediment permeabilities necessary for such flow have not been quantified. Here, we address this problem by combining (1) laboratory measurement of horizontal and vertical sediment permeability from a combination of constant rate of strain (CRS) consolidation tests and flow-through measurements on core samples; and (2) numerical models of fluid flow within a cross section perpendicular to the trench. In our models, we assign hydrostatic pressure at the top and seaward edges, a no-flow condition at the base of the sediments, and pore pressures ranging from 40%-100% of lithostatic at the arcward model boundary. We assign sediment permeability on the basis of our laboratory measurements, and evaluate the possible role of thin permeable conduits as well as strong anisotropy in the incoming section. Our laboratory results define a systematic log-linear relationship between sediment permeability and porosity within the LSB mudstones. The overall variation in permeability for our suite of samples is ~1 order of magnitude. Notably, horizontal permeabilities fall within the range of measured vertical permeabilities, and indicate no significant anisotropy. Using laboratory-derived permeability values, simulated horizontal flow rates range from 10-4 to 10-1 cm yr-1, and decrease dramatically with distance seaward of the trench. With permeability anisotropy of 1000x (i.e. kh = 1000kv), simulated flow rates peak at 3 cm yr-1 at the trench, and decrease to 3x10-1 cm yr-1 by 10 km seaward. These flow rates are substantially lower than those inferred from the geochemical data and also lower than the plate convergence rate of 4 cm yr-1, such that net transport of fluids out of the subduction zone is not likely. If discrete conduits are included in our models, permeabilities of ~10-114m2 are required to sustain the inferred flow rates. However, no potential conduits in the LSB were observed by coring or logging- while-drilling. In contrast, net egress of fluids - and associated chemical transport and pressure translation - are plausible at margins where continuous permeable strata are subducting. Overall, our results highlight a major discrepancy between constraints on fluid flow derived from physical hydrogeology and inferences from geochemical data. In this case, we suggest that the chemical signals may be affected by other processes such as in situ clay dehydration and down-section chemical variations.

Inferring Firn Permeability from Pneumatic Testing: A Case Study on the Greenland Ice Sheet

NASA Astrophysics Data System (ADS)

Sommers, Aleah N.; Rajaram, Harihar; Weber, Eliezer P.; MacFerrin, Michael J.; Colgan, William T.; Stevens, C. Max

2017-03-01

Across the accumulation zone of the Greenland ice sheet, summer temperatures can be sufficiently warm to cause widespread melting, as was the case in July 2012 when the entire ice sheet experienced a brief episode of enhanced surface ablation. The resulting meltwater percolates into the firn and refreezes, to create ice lenses and layers within the firn column. This is an important process to consider when estimating the surface mass balance of the ice sheet. The rate of meltwater percolation depends on the permeability of the firn, a property that is not well constrained in the presence of refrozen ice layers and lenses. We present a novel, inexpensive method for measuring in-situ firn permeability using pneumatic testing, a well-established technique used in environmental engineering and hydrology. To illustrate the capabilities of this method, we estimate both horizontal and vertical permeability from pilot tests at six sites on the Greenland ice sheet: KAN-U, DYE-2, EKT, NASA-SE, Saddle, and EastGRIP. These sites cover a range of conditions from mostly dry firn (EastGRIP), to firn with several ice layers and lenses from refrozen meltwater (Saddle, NASA-SE, EKT), to firn with extensive ice layers (DYE-2 and KAN-U). The estimated permeability in firn without refrozen ice layers at EastGRIP agrees well with the range previously reported using an air permeameter to measure permeability through firn core samples at Summit, Greenland. At sites with ice lenses or layers, we find high degrees of anisotropy, with vertical permeability much lower than horizontal permeability. Pneumatic testing is a promising and low-cost technique for measuring firn permeability, particularly as meltwater production increases in the accumulation zone and ice layers and lenses from refrozen melt layers become more prevalent. In these initial proof-of-concept tests, the estimated permeabilities represent effective permeability at the meter scale. With appropriately higher vacuum pressures and more detailed monitoring, effective permeabilities over a larger scale may be quantified reliably, and multiple measurements during a season and across multiple years could improve understanding of the evolving firn structure and permeability. The technique is also suitable for broad application in Antarctica and other glaciers and ice caps.

Voltage-dependent conformational changes in connexin channels.

PubMed

Bargiello, Thaddeus A; Tang, Qingxiu; Oh, Seunghoon; Kwon, Taekyung

2012-08-01

Channels formed by connexins display two distinct types of voltage-dependent gating, termed V(j)- or fast-gating and loop- or slow-gating. Recent studies, using metal bridge formation and chemical cross-linking have identified a region within the channel pore that contributes to the formation of the loop-gate permeability barrier. The conformational changes are remarkably large, reducing the channel pore diameter from 15 to 20Å to less than 4Å. Surprisingly, the largest conformational change occurs in the most stable region of the channel pore, the 3(10) or parahelix formed by amino acids in the 42-51 segment. The data provide a set of positional constraints that can be used to model the structure of the loop-gate closed state. Less is known about the conformation of the V(j)-gate closed state. There appear to be two different mechanisms; one in which conformational changes in channel structure are linked to a voltage sensor contained in the N-terminus of Cx26 and Cx32 and a second in which the C-terminus of Cx43 and Cx40 may act either as a gating particle to block the channel pore or alternatively to stabilize the closed state. The later mechanism utilizes the same domains as implicated in effecting pH gating of Cx43 channels. It is unclear if the two V(j)-gating mechanisms are related or if they represent different gating mechanisms that operate separately in different subsets of connexin channels. A model of the V(j)-closed state of Cx26 hemichannel that is based on the X-ray structure of Cx26 and electron crystallographic structures of a Cx26 mutation suggests that the permeability barrier for V(j)-gating is formed exclusively by the N-terminus, but recent information suggests that this conformation may not represent a voltage-closed state. Closed state models are considered from a thermodynamic perspective based on information from the 3.5Å Cx26 crystal structure and molecular dynamics (MD) simulations. The applications of computational and experimental methods to define the path of allosteric molecular transitions that link the open and closed states are discussed. This article is part of a Special Issue entitled: The Communicating junctions, composition, structure and characteristics. Copyright © 2011 Elsevier B.V. All rights reserved.

A system to measure minute hydraulic permeability of nanometer scale devices in a non-destructive manner

NASA Astrophysics Data System (ADS)

Smith, Ross A.; Fleischman, Aaron J.; Fissell, William H.; Zorman, Christian A.; Roy, Shuvo

2011-04-01

We report an automated system for measuring the hydraulic permeability of nanoporous membranes in a tangential-flow configuration. The system was designed and built specifically for micromachined silicon nanoporous membranes (SNM) with monodisperse slit-shaped pores. These novel membranes are under development for water filtration, artificial organ and drug delivery applications. The filtration cell permits non-destructive testing of the membrane over many remove-modify-replace testing cycles, allowing for direct experiments into the effects of surface modifications on such membranes. The experimental apparatus was validated using microfluidic tubing with circular cross sections that provided similar fluidic resistances to SNM. Further validation was performed with SNM chips for which the pore dimensions were known from scanning electron microscopy measurements. The system was then used to measure the hydraulic permeability of nanoporous membranes before and after surface modification. The system yields measurements with low variance and excellent agreement with predicted values, providing a platform for determining pore sizes in micro/nanofluidic systems with tight pore size distributions to a higher degree of precision than can be achieved with traditional techniques.

Heterogeneous porous media: Fronts and noise

NASA Astrophysics Data System (ADS)

Chaouchel, M.; Rakotomalala, N.; Salin, D.; Xu, B.; Yortsos, Y. C.

Capillary effects can be important in immiscible flows in heterogeneous media, particularly at low capillary numbers (Ca). We present experiments and simulations of slow drainage in 3-D porous media, either homogeneous and in the presence of buoyancy or heterogeneous and in its absence. An acoustic technique allows for an accurate study of the 3-D fronts and the cross-over region. Our results suggest that both cases can be described by invasion percolation in a gradient. Both front tails scale with the corresponding Bond numbers as σft≈B-47 in agreement with the theory. An analogous scaling for viscous effects is also given. The noise of these fronts are found correlated in the form of a fractional Brownian motion (fBm) of a Hurst exponent H≈.5. At higher Ca, experiments performed in 3-D porous media with sharp changes in permeability, exhibit a saturation profile response closely linked to the permeability variations. This viscous response to heterogeneity provides an opportunity to investigate and determine correlated (even at all scales, i.e. fBm), permeability fields.

Permeability Study of Polyphenols Derived from a Phenolic-Enriched Hibiscus sabdariffa Extract by UHPLC-ESI-UHR-Qq-TOF-MS.

PubMed

Borrás-Linares, Isabel; Herranz-López, María; Barrajón-Catalán, Enrique; Arráez-Román, David; González-Álvarez, Isabel; Bermejo, Marival; Fernández Gutiérrez, Alberto; Micol, Vicente; Segura-Carretero, Antonio

2015-08-07

Previous findings on the capacity of Hibiscus sabdariffa (HS) polyphenols to ameliorate metabolic disturbances justify the necessity of studies oriented to find the potential metabolites responsible for such an effect. The present study examined the intestinal epithelial membrane permeability of polyphenols present in a phenolic-enriched Hibiscus sabdariffa extract (PEHS), free and encapsulated, using the Caco-2 cell line. Additionally, selected polyphenols (quercetin, quercetin-3-glucoside, quercetin-3-glucuronide, and N-feruloyltyramine) were also studied in the same absorption model. The powerful analytical platform used ultra-high-performance liquid chromatography coupled with ultra-high-resolution quadrupole time-of-flight mass spectrometry (UHPLC-ESI-UHR-Qq-TOF-MS), and enabled the characterization of seven new compounds in PEHS. In the permeation study, only a few compounds were able to cross the cell monolayer and the permeability was lower when the extract was in an encapsulated form. Pure compounds showed a moderate absorption in all cases. Nevertheless, these preliminary results may need further research to understand the complete absorption mechanism of Hibiscus polyphenols.

Permeability Study of Polyphenols Derived from a Phenolic-Enriched Hibiscus sabdariffa Extract by UHPLC-ESI-UHR-Qq-TOF-MS

PubMed Central

Borrás-Linares, Isabel; Herranz-López, María; Barrajón-Catalán, Enrique; Arráez-Román, David; González-Álvarez, Isabel; Bermejo, Marival; Gutiérrez, Alberto Fernández; Micol, Vicente; Segura-Carretero, Antonio

2015-01-01

Previous findings on the capacity of Hibiscus sabdariffa (HS) polyphenols to ameliorate metabolic disturbances justify the necessity of studies oriented to find the potential metabolites responsible for such an effect. The present study examined the intestinal epithelial membrane permeability of polyphenols present in a phenolic-enriched Hibiscus sabdariffa extract (PEHS), free and encapsulated, using the Caco-2 cell line. Additionally, selected polyphenols (quercetin, quercetin-3-glucoside, quercetin-3-glucuronide, and N-feruloyltyramine) were also studied in the same absorption model. The powerful analytical platform used ultra-high-performance liquid chromatography coupled with ultra-high-resolution quadrupole time-of-flight mass spectrometry (UHPLC-ESI-UHR-Qq-TOF-MS), and enabled the characterization of seven new compounds in PEHS. In the permeation study, only a few compounds were able to cross the cell monolayer and the permeability was lower when the extract was in an encapsulated form. Pure compounds showed a moderate absorption in all cases. Nevertheless, these preliminary results may need further research to understand the complete absorption mechanism of Hibiscus polyphenols. PMID:26262611

ToxiM: A Toxicity Prediction Tool for Small Molecules Developed Using Machine Learning and Chemoinformatics Approaches.

PubMed

Sharma, Ashok K; Srivastava, Gopal N; Roy, Ankita; Sharma, Vineet K

2017-01-01

The experimental methods for the prediction of molecular toxicity are tedious and time-consuming tasks. Thus, the computational approaches could be used to develop alternative methods for toxicity prediction. We have developed a tool for the prediction of molecular toxicity along with the aqueous solubility and permeability of any molecule/metabolite. Using a comprehensive and curated set of toxin molecules as a training set, the different chemical and structural based features such as descriptors and fingerprints were exploited for feature selection, optimization and development of machine learning based classification and regression models. The compositional differences in the distribution of atoms were apparent between toxins and non-toxins, and hence, the molecular features were used for the classification and regression. On 10-fold cross-validation, the descriptor-based, fingerprint-based and hybrid-based classification models showed similar accuracy (93%) and Matthews's correlation coefficient (0.84). The performances of all the three models were comparable (Matthews's correlation coefficient = 0.84-0.87) on the blind dataset. In addition, the regression-based models using descriptors as input features were also compared and evaluated on the blind dataset. Random forest based regression model for the prediction of solubility performed better ( R 2 = 0.84) than the multi-linear regression (MLR) and partial least square regression (PLSR) models, whereas, the partial least squares based regression model for the prediction of permeability (caco-2) performed better ( R 2 = 0.68) in comparison to the random forest and MLR based regression models. The performance of final classification and regression models was evaluated using the two validation datasets including the known toxins and commonly used constituents of health products, which attests to its accuracy. The ToxiM web server would be a highly useful and reliable tool for the prediction of toxicity, solubility, and permeability of small molecules.

ToxiM: A Toxicity Prediction Tool for Small Molecules Developed Using Machine Learning and Chemoinformatics Approaches

PubMed Central

Sharma, Ashok K.; Srivastava, Gopal N.; Roy, Ankita; Sharma, Vineet K.

2017-01-01

The experimental methods for the prediction of molecular toxicity are tedious and time-consuming tasks. Thus, the computational approaches could be used to develop alternative methods for toxicity prediction. We have developed a tool for the prediction of molecular toxicity along with the aqueous solubility and permeability of any molecule/metabolite. Using a comprehensive and curated set of toxin molecules as a training set, the different chemical and structural based features such as descriptors and fingerprints were exploited for feature selection, optimization and development of machine learning based classification and regression models. The compositional differences in the distribution of atoms were apparent between toxins and non-toxins, and hence, the molecular features were used for the classification and regression. On 10-fold cross-validation, the descriptor-based, fingerprint-based and hybrid-based classification models showed similar accuracy (93%) and Matthews's correlation coefficient (0.84). The performances of all the three models were comparable (Matthews's correlation coefficient = 0.84–0.87) on the blind dataset. In addition, the regression-based models using descriptors as input features were also compared and evaluated on the blind dataset. Random forest based regression model for the prediction of solubility performed better (R2 = 0.84) than the multi-linear regression (MLR) and partial least square regression (PLSR) models, whereas, the partial least squares based regression model for the prediction of permeability (caco-2) performed better (R2 = 0.68) in comparison to the random forest and MLR based regression models. The performance of final classification and regression models was evaluated using the two validation datasets including the known toxins and commonly used constituents of health products, which attests to its accuracy. The ToxiM web server would be a highly useful and reliable tool for the prediction of toxicity, solubility, and permeability of small molecules. PMID:29249969

Petrophysical Properties of the Yeso, Abo and Cisco Formations in the Permian Basin in New Mexico, U.S.A

NASA Astrophysics Data System (ADS)

Mann, Griffin

The area that comprises the Northwest Shelf in Lea Co., New Mexico has been heavily drilled over the past half century. The main target being shallow reservoirs within the Permian section (San Andres and Grayburg Formations). With a focus shifting towards deeper horizons, there is a need for more petrophysical data pertaining to these formations, which is the focus of this study through a variety of techniques. This study involves the use of contact angle measurements, fluid imbibition tests, Mercury Injection Capillary Pressure (MICP) and log analysis to evaluate the nano-petrophysical properties of the Yeso, Abo and Cisco Formation within the Northwest Shelf area of southeast New Mexico. From contact angle measurements, all of the samples studied were found to be oil-wetting as n-decane spreads on to the rock surface much quicker than the other fluids (deionized water and API brine) tested. Imbibition tests resulted in a well-connected pore network being observed for all of the samples with the highest values of imbibition slopes being recorded for the Abo samples. MICP provided a variety of pore structure data which include porosity, pore-throat size distributions, permeability and tortuosity. The Abo samples saw the highest porosity percentages, which were above 15%, with all the other samples ranging from 4 - 7%. The majority of the pore-throat sizes for most of the samples fell within the 1 - 10 mum range. The only exceptions to this being the Paddock Member within the Yeso Formation, which saw a higher percentage of larger pores (10 - 1000mum) and one of the Cisco Formation samples, which had the majority of its pore sizes fall in the 0.1 - 1 mum range. The log analysis created log calculations and curves for cross-plot porosity and water saturation that were then used to derive a value for permeability. The porosity and permeability values were comparable with those measured from our MICP and literature values.

Assessment of Jahn permeable mortar system in a historic bridge abutment application.

DOT National Transportation Integrated Search

2015-06-01

Increasingly, the importance of historic preservation is competing with the requirements to enhance : structural capacity of older unique structures. Preservation of the functional and aesthetic qualities limits : potential change to meet the expande...

The main factors controlling petrophysical alteration in hydrothermal systems of the Kuril-Kamchatka island arch

NASA Astrophysics Data System (ADS)

Frolova, J.; Ladygin, V.; Rychagov, S.; Shanina, V.; Blyumkina, M.

2009-04-01

This report is based on the results of petrophysical studies obtained on a number of hydrothermal systems in the Kuril-Kamchatka island arc (Pauzhetsky, Mutnovsky, Koshelevsky, Essovsky, a volcano of Ebeko, Oceansky). Mineral composition and pore-space structure of primary rocks change intensively during hydrothermal process, results in alteration of petrophysical properties - porosity, density, permeability, hygroscopy, sonic velocity, elastic modulus, mechanical properties, thermal and magnetic characteristics. Petrophysical alterations gradually lead to the change of the structure of hydrothermal system, and its hydrodynamic and temperature regime. The tendency of petrophysical alteration can be different. In some cases rocks "improvement" is observed i.e. consolidation, hardening, decrease of porosity and permeability, removal of hygroscopy. In other cases rocks "deterioration" occurs, i.e. formation of secondary porosity and permeability, a decrease of density, strength, and elastic modulus, and occurrence of hygroscopic moisture. The classical example of cardinal petrophysical alteration is the transformation of hard basalts to plastic clays. The opposite example is the transformation of only slightly consolidates porous tuffs to hard and dense secondary quartzite. The character of petrophysical alteration depends on a number of factors including peculiarities of primary rocks, temperature, pressure and composition of thermal fluids, duration of fluid-rock interaction, and condition of fluid (steam, water, boiling water). The contribution of each factor to change of volcanic rocks properties is considered and analyzed in details. In particular, primary rocks controls speed, intensity and character of petrophysical alterations. Factors favorable for alteration are high porosity and permeability, micro crakes, weak cementation, glassy structure, basaltic composition. Kuril-Kamchatka region represents the volcanic island arch so host rocks in hydrothermal systems are mainly volcanic or volcaniclastic types of Neogene-Quaternary age. Volcanic rocks (lava rocks) are dense with high strength and elastic modulus and low porosity and permeability. The speed of their alteration is low. Basically volcanic rocks form impermeable horizons in the structure of hydrothermal system. But sometimes they form fracture-type reservoir. The origin of fracturing can be various. Volcanoclastic rocks are characterized by lower physical and mechanical properties, higher porosity and permeability. Due to high porosity and permeability they are greatly exposed to thermal fluids so they are altered intensively. Volcaniclastic rocks are the most common host rocks of geothermal reservoirs. Typically they form porous or fracture-porous aquifers. But in some cases they form water confining layers. The well-studied example is Pauzhetskaya hydrothermal system. The main reservoir is composed of highly porous (30-40%) and permeable medium-grained tuffs. The caprock is composed of fine-grained argillized tuffs. They are highly porous but due to small pore size porosity is un-effective for fluid and permeability is low. The temperature and pressure in a hydrothermal system cardinally influence on rocks properties. High-temperature deep fluids (Т>200C) cause the perfect tendency of petrophysical alteration - consolidation, hardening, a decrease of porosity and permeability, and removal of a hygroscopic moisture. This petrophysical tendency is observed independently of composition of fluids. This is the result of the development of high-temperature secondary minerals, which fill pores and cracks, and substitute matrix and phenocrystals. The contacts between grains become strong and dense, intergranular porosity is disappeared that reinforces cementation of rock. The petrophysical alteration caused by low-temperature subsurface fluids (Т<150C) are more difficult and diverse. Depending on what process prevails - rocks leaching, sedimentation of secondary minerals in pores and cracks or replacement of primary minerals by secondary minerals, it can lead to both: an increase or a decrease in petrophysical properties. Financial support from RFBR (project 05-07-00118-a)

A comparison of etched-geometry and overgrown silicon permeable base transistors by two-dimensional numerical simulations

NASA Astrophysics Data System (ADS)

Vojak, B. A.; Alley, G. D.

1983-08-01

Two-dimensional numerical simulations are used to compare etched geometry and overgrown Si permeable base transistors (PTBs), considering both the etched collector and etched emitter biasing conditions made possible by the asymmetry of the etched structure. In PTB devices, the two-dimensional nature of the depletion region near the Schottky contact base grating results in a smaller electron barrier and, therefore, a larger collector current in the etched than in the overgrown structure. The parasitic feedback effects which result at high base-to-emitter bias levels lead to a deviation from the square-law behavior found in the collector characteristics of the overgrown PBT. These structures also have lower device capacitances and smaller transconductances at high base-to-emitter voltages. As a result, overgrown and etched structures have comparable predicted maximum values of the small signal unity short-circuit current gain frequency and maximum oscillation frequency.

Reduction in lipophilicity improved the solubility, plasma–protein binding, and permeability of tertiary sulfonamide RORc inverse agonists

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

Fauber, Benjamin P.; René, Olivier; de Leon Boenig, Gladys

2014-08-01

Using structure-based drug design principles, we identified opportunities to reduce the lipophilicity of our tertiary sulfonamide RORc inverse agonists. The new analogs possessed improved RORc cellular potencies with >77-fold selectivity for RORc over other nuclear receptors in our cell assay suite. The reduction in lipophilicity also led to an increased plasma–protein unbound fraction and improvements in cellular permeability and aqueous solubility.

Physiological barriers to the oral delivery of curcumin.

PubMed

Berginc, K; Trontelj, J; Basnet, N Skalko; Kristl, A

2012-06-01

Curcumin, a principal component from Curcuma longa, with antioxidant and anti-inflammatory activities was proposed as a potential candidate for the preventation and/or treatment of cancer and chronic diseases. However, curcumin could not achieve its expected therapeutic outcome in clinical trials due to its low solubility and poor bioavailability. The actual intestinal physiological barriers limiting curcumin absorption after oral administration have not been fully investigated. To identify the main barriers curtailing its absorption, in vitro permeability of curcumin and flux of its glucuronide were monitored in rat jejunum and Transwell grown Caco-2 cells. Curcumin was more permeable under acidic conditions, but the permeability was substantially below the permeability of highly permeable standards. Its efflux could not be inhibited by specific Pgp and MRP inhibitors. BCRP was found to participate in curcumin transport, but the Organic Anion Transporting Polypeptide (OATP) did not. The permeability of curcumin significantly increased when the structure of mucus was compromised. The inhibitor of curcumin metabolism, piperin, failed to act as a permeability enhancer. Piperin inhibited Pgp and MRP transporters and decreased the amount of glucuronide transported back into the intestine. Inclusion of piperin in curcumin-containing formulations is highly recommended as to inhibit curcumin glucuronidation and to increase the transport of formed glucuronides into the plasma, therefore increasing the probability of glucuronide distribution into target tissue and inter-convertion to curcumin. It would also be beneficial, if curcumin delivery systems could reversibly compromise the mucous integrity to minimize the non-specific binding of curcumin to its constituents.

On the Examination of Darcy Permeability a Thin Fibrous Porous Layer

NASA Astrophysics Data System (ADS)

Zhu, Zenghao; Wang, Qiuyun; Wu, Qianhong; Vucbmss Team

2016-11-01

In this paper, we report a novel experimental approach to investigate the Darcy permeability of a soft and thin fibrous porous layer. The project is inspired by recent studies involved compression of very thin porous films and the resultant pore fluid flow inside the confined porous structure. The Darcy permeability plays a critical role during the process, which however, is tricky to measure due to the very thin nature of the porous media. In the current study, a special micro-fluidic device is developed that consists of a rectangular flow channel with adjustable gap height ranging from 20 mm to 0.5 mm. Air is forced through the thin gap filled with testing fibrous materials. By measuring the flow rate and the pressure drop, we have successfully obtained the Darcy permeability of different thin porous sheets at different compression ratios. Furthermore, the surface area of the fibers are evaluated using a Micromeritics® ASAP 2020 (Accelerated Surface Area and Porosimetry) system. We found that, although the functions relating the permeability and porosities are different for different fibrous materials, these functions collapse to a single relationship if one express the permeability as a function of the solid phase surface area per unit volume. This finding provides a useful approach to evaluate the permeability of very thin fibrous porous sheet, which otherwise is difficult to measure directly. This research was supported by the National Science Foundation under Award #1511096.

MIL-53 frameworks in mixed-matrix membranes and cross-linked ZIF-8/matrimidRTM mixed-matrix membranes for gas separation

NASA Astrophysics Data System (ADS)

Hsieh, Josephine Ordonez

Mixed matrix membranes (MMMs) are hybrid materials consisting of two phases: an inorganic nanoscale particle as the discrete phase, and a polymeric material as the continuous phase. The incorporation of inorganic particles into a polymer can improve a membrane's overall separation performance. MMMs incorporating metal-organic frameworks (MOFs) have exhibited promising gas separation performance. MOFs are inorganic-organic crystals constructed from metal ions that are linked by polydentate ligands. Zeolitic imidazolate frameworks (ZIFs) are a sub-class of MOFs that uses imidazole analogues as ligands. In these studies, the MOF MIL-53 and ZIF-8 were successfully synthesized and characterized by a battery of analytical techniques including XRD, FTIR, TGA, N2 adsorption, and SEM, and were incorporated into MMMs with Matrimid® polymer. In chapter 1, MIL-53/Matrimid® MMMs containing MIL-53-ht (open-pore form) were fabricated, characterized and obtained permeability values higher than Matrimid®. Selectivities decreased for the gas pairs of O2/N2, H2/O2, H2/CO2, and H2/N2. However, slight enhancement of the CO2/CH4 selectivity was observed for the MIL-53-ht/Matrimid® compared to that of Matrimid ®. The MIL-53-as/Matrimid® MMM also showed an increase in permeability as well as an increase in selectivity for the gas pairs H2/O2, CO2/CH4, H 2/CH4, and H2/N2. The MIL-53-lt/Matrimid ® MMM showed that it does not retain its closed-pore form in the MMM due to chloroform solvent opening the pores and eventually polymer confinement of the MIL 53 framework in the MMM. In chapter 2, easy synthesis and fabrication of the MIL-53 MOF membrane was realized using a seeded growth method with a commercially available alumina TLC plate. The MOF membrane had a well-intergrown and dense layer of MIL-53 crystals on the surface of the alumina substrate. The MIL-53 crystals were also converted to the MIL-53-lt (closed-pore form) after heating at 330 °C and cooling to room temperature, which confirms the breathing ability of the MOF. In chapter 3, a comprehensive approach for membrane materials in order to achieve high productivity and separation efficiency was applied by incorporating additives into polymers and cross-linking the resulting MMM that could lead to increase and simultaneous selectivity enhancement. ZIF-8 was used as an additive in these MMMs. ZIF-8 can readily absorb small gases such, as H 2 and CO2 due to its 3.4 Å pore aperture. ZIF-8/Matrimid ® MMMs were fabricated with a spin-coated Matrimid® layer on one surface and cross-linked with EDA vapor. This membrane morphology could lead to enhanced selectivities due to the cross-linked layer, at the same time maintain the high permeability of the bulk MMM. The permeabilities decreased for the cross-linked, spin-coated Matrimid® ZIF-8/Matrimid ® MMMs. However, there was enhancement in selectivities for H 2/CO2, H2/N2, H2/O 2 and H2/CH4 gas pairs, which can be due to reduction of diffusive pathways for larger gas molecules. Compared to uncross-linked ZIF-8/Matrimid® MMMs, the cross-linked, spin-coated Matrimid ® ZIF-8/Matrimid® MMMs lie close to the Robeson's upper bound for H2/CO2 suggesting its potential for this gas pair separation.

Transient pressure-pulse decay permeability measurements in the Barnett shale

NASA Astrophysics Data System (ADS)

Bhandari, A. R.; Reece, J.; Cronin, M. B.; Flemings, P. B.; Polito, P. J.

2012-12-01

We conducted transient pressure-pulse decay permeability measurements on core plugs of the Barnett shale using a hydrostatic pressure cell. Core plugs, 3.8 cm in diameter and less than 2.5 cm in length, were prepared from a core obtained at a depth of approximately 2330 m from the Mitchel Energy 2 T. P. Sims well in the Mississippian Barnett Formation (Loucks and Ruppel, 2007). We performed permeability measurements of the core plugs using argon at varying confining pressures in two different directions (perpendicular and parallel to bedding planes). We calculate gas permeability from changes in pressure with time using the analytical solution of the pressure diffusion equation with appropriate boundary conditions for our test setup (Dicker and Smits, 1988). Based on our limited results, we interpret 2 × 10-18 m2 for vertical permeability and 156 × 10-18 m2 for horizontal permeability. We demonstrate an extreme stress dependence of the horizontal flow permeability where permeability decreases from 156 × 10-18 m2 to 2.5 × 10-18 m2 as the confining stress is increased from 3.5 to 35 MPa. These permeability measurements are at the high side of other pulsed permeability measurements in the Barnett shale (Bustin et al. 2008; Vermylen, 2011). Permeabilities calculated from mercury injection capillary pressure curves, using theoretically derived permeability-capillary pressure models based on parallel tubes assumption, are orders of magnitude less than our transient pressure-pulse decay permeability measurements (for example, 3.7×10-21 m2 (this study), 10-21 -10-20 m2 (Sigal, 2007), 10-20 -10-17 m2 (Prince et al., 2010)). We interpret that the high measured permeabilities are due to microfractures in the sample. At this point, we do not know if the microfractures are due to sampling disturbance (stress-relief induced) or represent an in-situ fracture network. Our study illustrates the importance of characterization of microfractures at the core scale to understand better the transport behavior in shale matrix and sealing efficiency of cap rocks. References Bustin et al. (2008), Impact of shale properties on pore structure and storage characteristics, SPE 119892. Dicker and Smits (1988), A practical method for determining permeability from laboratory pressure-pulse decay measurements, SPE 17578. Loucks and Ruppel (2007), Mississippian Barnett Shale: Lithofacies and depositional setting of a deep-water shale gas succession in the Fort Worth Basin, Texas, AAPG 2007. Sigal (2007), Mercury capillary pressure measurements on Barnett core. (http://shale.ou.edu/Home/Publication) Prince et al. (2010), Shale diagenesis and permeability: examples from the Barnett shale and the Marcellus formation, AAPG 2010. Vermylen, J.P. (2011), Geomechanical studies of the Barnett Shale, Texas, USA, PhD thesis, Stanford University.

Transmural Intestinal Wall Permeability in Severe Ischemia after Enteral Protease Inhibition

PubMed Central

Altshuler, Angelina E.; Lamadrid, Itze; Li, Diana; Ma, Stephanie R.; Kurre, Leena; Schmid-Schönbein, Geert W.; Penn, Alexander H.

2014-01-01

In intestinal ischemia, inflammatory mediators in the small intestine's lumen such as food byproducts, bacteria, and digestive enzymes leak into the peritoneal space, lymph, and circulation, but the mechanisms by which the intestinal wall permeability initially increases are not well defined. We hypothesize that wall protease activity (independent of luminal proteases) and apoptosis contribute to the increased transmural permeability of the intestine's wall in an acutely ischemic small intestine. To model intestinal ischemia, the proximal jejunum to the distal ileum in the rat was excised, the lumen was rapidly flushed with saline to remove luminal contents, sectioned into equal length segments, and filled with a tracer (fluorescein) in saline, glucose, or protease inhibitors. The transmural fluorescein transport was determined over 2 hours. Villi structure and epithelial junctional proteins were analyzed. After ischemia, there was increased transmural permeability, loss of villi structure, and destruction of epithelial proteins. Supplementation with luminal glucose preserved the epithelium and significantly attenuated permeability and villi damage. Matrix metalloproteinase (MMP) inhibitors (doxycycline, GM 6001), and serine protease inhibitor (tranexamic acid) in the lumen, significantly reduced the fluorescein transport compared to saline for 90 min of ischemia. Based on these results, we tested in an in-vivo model of hemorrhagic shock (90 min 30 mmHg, 3 hours observation) for intestinal lesion formation. Single enteral interventions (saline, glucose, tranexamic acid) did not prevent intestinal lesions, while the combination of enteral glucose and tranexamic acid prevented lesion formation after hemorrhagic shock. The results suggest that apoptotic and protease mediated breakdown cause increased permeability and damage to the intestinal wall. Metabolic support in the lumen of an ischemic intestine with glucose reduces the transport from the lumen across the wall and enteral proteolytic inhibition attenuates tissue breakdown. These combined interventions ameliorate lesion formation in the small intestine after hemorrhagic shock. PMID:24805256

Effects of Streptomycin Administration on Increases in Skeletal Muscle Fiber Permeability and Size Following Eccentric Muscle Contractions.

PubMed

Hayao, Keishi; Tamaki, Hiroyuki; Nakagawa, Kouki; Tamakoshi, Keigo; Takahashi, Hideaki; Yotani, Kengo; Ogita, Futoshi; Yamamoto, Noriaki; Onishi, Hideaki

2018-06-01

The purpose of this study was to investigate the preventive effect of streptomycin (Str) administration on changes in membrane permeability and the histomorphological characteristics of damaged muscle fibers following eccentric contraction (ECC ). Eighteen 7-week-old male Fischer 344 rats were randomly assigned to three groups: control (Cont), ECC, and ECC with Str (ECC + Str). The tibialis anterior (TA) muscles in both ECC groups were stimulated electrically and exhibited ECC. Evans blue dye (EBD), a marker of muscle fiber damage associated with increased membrane permeability, was injected 24 hr before TA muscle sampling. The number of EBD-positive fibers, muscle fiber cross-sectional area (CSA), and roundness were determined via histomorphological analysis. The ECC intervention resulted in an increased fraction of EBD-positive fibers, a larger CSA, and decreased roundness. The fraction of EBD-positive fibers was 79% lower in the ECC + Str group than in the ECC group. However, there was no difference in the CSA and roundness of the EBD-positive fibers between the two ECC groups. These results suggest that Str administration can reduce the number of myofibers that increase membrane permeability following ECC, but does not ameliorate the extent of fiber swelling in extant EBD-positive fibers. Anat Rec, 301:1096-1102, 2018. © 2018 Wiley Periodicals, Inc. © 2018 Wiley Periodicals, Inc.

Simulation of Groundwater Mounding Beneath Hypothetical Stormwater Infiltration Basins

USGS Publications Warehouse

Carleton, Glen B.

2010-01-01

Groundwater mounding occurs beneath stormwater management structures designed to infiltrate stormwater runoff. Concentrating recharge in a small area can cause groundwater mounding that affects the basements of nearby homes and other structures. Methods for quantitatively predicting the height and extent of groundwater mounding beneath and near stormwater Finite-difference groundwater-flow simulations of infiltration from hypothetical stormwater infiltration structures (which are typically constructed as basins or dry wells) were done for 10-acre and 1-acre developments. Aquifer and stormwater-runoff characteristics in the model were changed to determine which factors are most likely to have the greatest effect on simulating the maximum height and maximum extent of groundwater mounding. Aquifer characteristics that were changed include soil permeability, aquifer thickness, and specific yield. Stormwater-runoff variables that were changed include magnitude of design storm, percentage of impervious area, infiltration-structure depth (maximum depth of standing water), and infiltration-basin shape. Values used for all variables are representative of typical physical conditions and stormwater management designs in New Jersey but do not include all possible values. Results are considered to be a representative, but not all-inclusive, subset of likely results. Maximum heights of simulated groundwater mounds beneath stormwater infiltration structures are the most sensitive to (show the greatest change with changes to) soil permeability. The maximum height of the groundwater mound is higher when values of soil permeability, aquifer thickness, or specific yield are decreased or when basin depth is increased or the basin shape is square (and values of other variables are held constant). Changing soil permeability, aquifer thickness, specific yield, infiltration-structure depth, or infiltration-structure shape does not change the volume of water infiltrated, it changes the shape or height of the groundwater mound resulting from the infiltration. An aquifer with a greater soil permeability or aquifer thickness has an increased ability to transmit water away from the source of infiltration than aquifers with lower soil permeability; therefore, the maximum height of the groundwater mound will be lower, and the areal extent of mounding will be larger. The maximum height of groundwater mounding is higher when values of design storm magnitude or percentage of impervious cover (from which runoff is captured) are increased (and other variables are held constant) because the total volume of water to be infiltrated is larger. The larger the volume of infiltrated water the higher the head required to move that water away from the source of recharge if the physical characteristics of the aquifer are unchanged. The areal extent of groundwater mounding increases when soil permeability, aquifer thickness, design-storm magnitude, or percentage of impervious cover are increased (and values of other variables are held constant). For 10-acre sites, the maximum heights of the simulated groundwater mound range from 0.1 to 18.5 feet (ft). The median of the maximum-height distribution from 576 simulations is 1.8 ft. The maximum areal extent (measured from the edge of the infiltration basins) of groundwater mounding of 0.25-ft ranges from 0 to 300 ft with a median of 51 ft for 576 simulations. Stormwater infiltration at a 1-acre development was simulated, incorporating the assumption that the hypothetical infiltration structure would be a pre-cast concrete dry well having side openings and an open bottom. The maximum heights of the simulated groundwater-mounds range from 0.01 to 14.0 ft. The median of the maximum-height distribution from 432 simulations is 1.0 ft. The maximum areal extent of groundwater mounding of 0.25-ft ranges from 0 to 100 ft with a median of 10 ft for 432 simulations. Simulated height and extent of groundwater mounding associ

Fluorescein permeability and electrical resistance of human skin during low frequency ultrasound application.

PubMed

Cancel, Limary M; Tarbell, John M; Ben-Jebria, Abdellaziz

2004-09-01

Transdermal drug delivery offers an alternative to injections and oral medication but is limited by the low skin permeability of most drugs. The use of low-frequency ultrasound over long periods of time, typically over an hour, has been shown to enhance skin permeability, a phenomenon referred to as sonophoresis. In this study, we investigated the effects of short time sonication of human skin at 20 kHz and at variable intensities and duty cycles on the dynamics of fluorescein transport across the skin (permeability) as well as the changes in the skin's structural integrity (electrical resistance). We found that a short application of ultrasound enhanced the transport of fluorescein across human skin by a factor in the range of 2-9 for full thickness skin samples and by a factor in the range of 2-28 000 for heat-stripped stratum corneum samples (however, samples with very high (10(3)) enhancement were likely to have been damaged by ultrasound). The electrical resistance of the skin decreased by an average of 20% for full thickness samples and 58% for stratum corneum samples. Increasing the duty cycle from 10 to 60% caused a significant increase in permeability enhancement from 2.3 to 9.1, and an increase in intensity from 8 to 23 mW cm(-2) induced a significant increase in permeability enhancement from 2 to 7.4, indicating a clear dependence of the permeability on both duty cycle and intensity. The increase in solute flux upon ultrasound exposure was immediate, demonstrating for the first time the fast response dynamics of sonophoretic enhancement. In addition, a quantitative analysis of the thermal and convective dispersion effects associated with ultrasound application showed that each contributes significantly to the overall permeability enhancement observed.

Characterizing the Variable Dust Permeability of Planet-induced Gaps

NASA Astrophysics Data System (ADS)

Weber, Philipp; Benítez-Llambay, Pablo; Gressel, Oliver; Krapp, Leonardo; Pessah, Martin E.

2018-02-01

Aerodynamic theory predicts that dust grains in protoplanetary disks will drift radially inward on comparatively short timescales. In this context, it has long been known that the presence of a gap opened by a planet can significantly alter the dust dynamics. In this paper, we carry out a systematic study employing long-term numerical simulations aimed at characterizing the critical particle size for retention outside a gap as a function of particle size, as well as various key parameters defining the protoplanetary disk model. To this end, we perform multifluid hydrodynamical simulations in two dimensions, including different dust species, which we treat as pressureless fluids. We initialize the dust outside of the planet’s orbit and study under which conditions dust grains are able to cross the gap carved by the planet. In agreement with previous work, we find that the permeability of the gap depends both on dust dynamical properties and the gas disk structure: while small dust follows the viscously accreting gas through the gap, dust grains approaching a critical size are progressively filtered out. Moreover, we introduce and compute a depletion factor that enables us to quantify the way in which higher viscosity, smaller planet mass, or a more massive disk can shift this critical size to larger values. Our results indicate that gap-opening planets may act to deplete the inner reaches of protoplanetary disks of large dust grains—potentially limiting the accretion of solids onto forming terrestrial planets.

Effects of PLA Film Incorporated with ZnO Nanoparticle on the Quality Attributes of Fresh-Cut Apple.

PubMed

Li, Wenhui; Li, Lin; Cao, Yun; Lan, Tianqing; Chen, Haiyan; Qin, Yuyue

2017-07-31

A novel nanopackaging film was synthesized by incorporating ZnO nanoparticles into a poly-lactic acid (PLA) matrix, and its effect on the quality of fresh-cut apple during the period of preservation was investigated at 4 ± 1 °C for 14 days. Six wt % cinnamaldehyde was added into the nano-blend film. Scanning electron microscope (SEM) analysis showed a rougher cross-section of the nano-blend films and an X-ray diffraction (XRD) was carried out to determine the structure of the ZnO nanoparticles. Compared to the pure PLA film, the nano-blend film had a higher water vapor permeability (WVP) and lower oxygen permeability. With the increase of the nanoparticles (NPs) in the PLA, the elongation at break (ε) and elastic modulus (EM) increased, while tensile strength (TS) decreased. Thermogravimetric analysis (TGA) presented a relatively good thermostability. Most importantly, the physical and biochemical properties of the fresh-cut apple were also measured, such as weight loss, firmness, polyphenol oxidase (PPO), total phenolic content, browning index (BI), sensory quality, and microbiological level. The results indicated that nano-blend packaging films had the highest weight loss at the end of storage compared to the pure PLA film; however, nanopackaging provided a better retention of firmness, total phenolic countent, color, and sensory quality. It also had a remarkable inhibition on the growth of microorganisms. Therefore, Nano-ZnO active packaging could be used to improve the shelf-life of fresh-cut produce.

Effects of PLA Film Incorporated with ZnO Nanoparticle on the Quality Attributes of Fresh-Cut Apple

PubMed Central

Li, Lin; Cao, Yun; Lan, Tianqing; Chen, Haiyan

2017-01-01

A novel nanopackaging film was synthesized by incorporating ZnO nanoparticles into a poly-lactic acid (PLA) matrix, and its effect on the quality of fresh-cut apple during the period of preservation was investigated at 4 ± 1 °C for 14 days. Six wt % cinnamaldehyde was added into the nano-blend film. Scanning electron microscope (SEM) analysis showed a rougher cross-section of the nano-blend films and an X-ray diffraction (XRD) was carried out to determine the structure of the ZnO nanoparticles. Compared to the pure PLA film, the nano-blend film had a higher water vapor permeability (WVP) and lower oxygen permeability. With the increase of the nanoparticles (NPs) in the PLA, the elongation at break (ε) and elastic modulus (EM) increased, while tensile strength (TS) decreased. Thermogravimetric analysis (TGA) presented a relatively good thermostability. Most importantly, the physical and biochemical properties of the fresh-cut apple were also measured, such as weight loss, firmness, polyphenol oxidase (PPO), total phenolic content, browning index (BI), sensory quality, and microbiological level. The results indicated that nano-blend packaging films had the highest weight loss at the end of storage compared to the pure PLA film; however, nanopackaging provided a better retention of firmness, total phenolic countent, color, and sensory quality. It also had a remarkable inhibition on the growth of microorganisms. Therefore, Nano-ZnO active packaging could be used to improve the shelf-life of fresh-cut produce. PMID:28758980

Low Crossover Polymer Electrolyte Membranes for Direct Methanol Fuel Cells

NASA Technical Reports Server (NTRS)

Prakash, G. K. Surya; Smart, Marshall; Atti, Anthony R.; Olah, George A.; Narayanan, S. R.; Valdez, T.; Surampudi, S.

1996-01-01

Direct Methanol Fuel Cells (DMFC's) using polymer electrolyte membranes are promising power sources for portable and vehicular applications. State of the art technology using Nafion(R) 117 membranes (Dupont) are limited by high methanol permeability and cost, resulting in reduced fuel cell efficiencies and impractical commercialization. Therefore, much research in the fuel cell field is focused on the preparation and testing of low crossover and cost efficient polymer electrolyte membranes. The University of Southern California in cooperation with the Jet Propulsion Laboratory is focused on development of such materials. Interpenetrating polymer networks are an effective method used to blend polymer systems without forming chemical links. They provide the ability to modify physical and chemical properties of polymers by optimizing blend compositions. We have developed a novel interpenetrating polymer network based on poly (vinyl - difluoride)/cross-linked polystyrenesulfonic acid polymer composites (PVDF PSSA). Sulfonation of polystyrene accounts for protonic conductivity while the non-polar, PVDF backbone provides structural integrity in addition to methanol rejection. Precursor materials were prepared and analyzed to characterize membrane crystallinity, stability and degree of interpenetration. USC JPL PVDF-PSSA membranes were also characterized to determine methanol permeability, protonic conductivity and sulfur distribution. Membranes were fabricated into membrane electrode assemblies (MEA) and tested for single cell performance. Tests include cell performance over a wide range of temperatures (20 C - 90 C) and cathode conditions (ambient Air/O2). Methanol crossover values are measured in situ using an in-line CO2 analyzer.

Comparison of VOC and ammonia emissions from individual PVC materials, adhesives and from complete structures.

PubMed

Järnström, H; Saarela, K; Kalliokoski, P; Pasanen, A-L

2008-04-01

Emission rates of volatile organic compounds (VOCs) and ammonia measured from six PVC materials and four adhesives in the laboratory were compared to the emission rates measured on site from complete structures. Significantly higher specific emission rates (SERs) were generally measured from the complete structures than from individual materials. There were large differences between different PVC materials in their permeability for VOCs originating from the underlying structure. Glycol ethers and esters from adhesives used in the installation contributed to the emissions from the PVC covered structure. Emissions of 2-ethylhexanol and TXIB (2,2,4-trimethyl-1,3-pentanediol diisobutyrate) were common. High ammonia SERs were measured from single adhesives but their contribution to the emissions from the complete structure did not appear as obvious as for VOCs. The results indicate that three factors affected the VOC emissions from the PVC flooring on a structure: 1) the permeability of the PVC product for VOCs, 2) the VOC emission from the adhesive used, and 3) the VOC emission from the backside of the PVC product.

A Permeability Study of O2 and the Trace Amine p-Tyramine through Model Phosphatidylcholine Bilayers

PubMed Central

Holland, Bryan W.; Berry, Mark D.; Gray, C. G.; Tomberli, Bruno

2015-01-01

We study here the permeability of the hydrophobic O2 molecule through a model DPPC bilayer at 323K and 350K, and of the trace amine p-tyramine through PC bilayers at 310K. The tyramine results are compared to previous experimental work at 298K. Nonequilibrium work methods were used in conjunction to simultaneously obtain both the potential of mean force (PMF) and the position dependent transmembrane diffusion coefficient, D(z), from the simulations. These in turn were used to calculate the permeability coefficient, P, through the inhomogeneous solubility-diffusion model. The results for O2 are consistent with previous simulations, and agree with experimentally measured P values for PC bilayers. A temperature dependence in the permeability of O2 through DPPC was obtained, with P decreasing at higher temperatures. Two relevant species of p-tyramine were simulated, from which the PMF and D(z) were calculated. The charged species had a large energetic barrier to crossing the bilayer of ~ 21 kcal/mol, while the uncharged, deprotonated species had a much lower barrier of ~ 7 kcal/mol. The effective in silico permeability for p-tyramine was calculated by applying three approximations, all of which gave nearly identical results (presented here as a function of the pKa). As the permeability value calculated from simulation was highly dependent on the pKa of the amine group, a further pKa study was performed that also varied the fraction of the uncharged and zwitterionic p-tyramine species. Using the experimental P value together with the simulated results, we were able to label the phenolic group as responsible for the pKa1 and the amine for the pKa2, that together represent all of the experimentally measured pKa values for p-tyramine. This agrees with older experimental results, in contrast to more recent work that has suggested there is a strong ambiguity in the pKa values. PMID:26086933

Study on textile comfort properties of polypropylene blended stainless steel woven fabric for the application of electromagnetic shielding effectiveness

NASA Astrophysics Data System (ADS)

Palanisamy, S.; Tunakova, V.; Karthik, D.; Ali, A.; Militky, J.

2017-10-01

In this study, the different proportion of conductive component blended with polypropylene yarn were taken for making conductive textile samples for analysis of electromagnetic shielding effectiveness, fabric bending moment and air permeability. The ASTM D4935 coaxial transmission line method was used to study the electromagnetic shielding. Electromagnetic shielding effectiveness of textile structures containing different percentage of metal content ranges from 1 to 50 dB at high frequency range. Breathability of structures, more precisely air permeability was considered as one of important parameters for designing of electromagnetic radiation protective fabrics for certain applications. The bending moment of samples is decreases with increasing metal component percent.

Permeability and flammability study of composite sandwich structures for cryogenic applications

NASA Astrophysics Data System (ADS)

Bubacz, Monika

Fiber reinforced plastics offer advantageous specific strength and stiffness compared to metals and has been identified as candidates for the reusable space transportation systems primary structures including cryogenic tanks. A number of carbon and aramid fiber reinforced plastics have been considered for the liquid hydrogen tanks. Materials selection is based upon mechanical properties and containment performance (long and short term) and upon manufacturing considerations. The liquid hydrogen tank carries shear, torque, end load, and bending moment due to gusts, maneuver, take-off, landing, lift, drag, and fuel sloshing. The tank is pressurized to about 1.5 atmosphere (14.6psi or 0.1 MPa) differential pressure and on ascent maintains the liquid hydrogen at a temperature of 20K. The objective of the research effort into lay the foundation for developing the technology required for reliable prediction of the effects of various design, manufacturing, and service parameters on the susceptibility of composite tanks to develop excessive permeability to cryogenic fuels. Efforts will be expended on developing the materials and structural concepts for the cryogenic tanks that can meet the functional requirements. This will include consideration for double wall composite sandwich structures, with inner wall to meet the cryogenic requirements. The structure will incorporate nanoparticles for properties modifications and developing barriers. The main effort will be extended to tank wall's internal skin design. The main requirements for internal composite stack are: (1) introduction of barrier film (e.g. honeycomb material paper sheet) to reduce the wall permeability to hydrogen, (2) introduction of nanoparticles into laminate resin to prevent micro-cracking or crack propagation. There is a need to characterize and analyze composite sandwich structural damage due to burning and explosion. Better understanding of the flammability and blast resistance of the composite structures needs to be evaluated.

Water softening process

DOEpatents

Sheppard, John D.; Thomas, David G.

1976-01-01

This invention involves an improved process for softening hard water which comprises selectively precipitaing CaCO.sub.3 to form a thin layer thereof, increasing the pH of said water to precipitate magnesium as magnesium hydroxide and then filtering the resultant slurry through said layer. The CaCO.sub.3 layer serves as a thin permeable layer which has particularly useful application in cross-flow filtration applications.

Properties investigation of sulfonated poly(ether ether ketone)/polyacrylonitrile acid-base blend membrane for vanadium redox flow battery application.

PubMed

Li, Zhaohua; Dai, Wenjing; Yu, Lihong; Liu, Le; Xi, Jingyu; Qiu, Xinping; Chen, Liquan

2014-11-12

Acid-base blend membrane prepared from sulfonated poly(ether ether ketone) (SPEEK) and polyacrylonitrile (PAN) was detailedly evaluated for vanadium redox flow battery (VRFB) application. SPEEK/PAN blend membrane exhibited dense and homogeneous cross-section morphology as scanning electron microscopy and energy-dispersive X-ray spectroscopy images show. The acid-base interaction of ionic cross-linking and hydrogen bonding between SPEEK and PAN could effectively reduce water uptake, swelling ratio, and vanadium ion permeability, and improve the performance and stability of blend membrane. Because of the good balance of proton conductivity and vanadium ion permeability, blend membrane with 20 wt % PAN (S/PAN-20%) showed higher Coulombic efficiency (96.2% vs 91.1%) and energy efficiency (83.5% vs 78.4%) than Nafion 117 membrane at current density of 80 mA cm(-2) when they were used in VRFB single cell. Besides, S/PAN-20% membrane kept a stable performance during 150 cycles at current density of 80 mA cm(-2) in the cycle life test. Hence the SPEEK/PAN acid-base blend membrane could be used as promising candidate for VRFB application.

Transient viscous response of the human cornea probed with the Surface Force Apparatus.

PubMed

Zappone, Bruno; Patil, Navinkumar J; Lombardo, Marco; Lombardo, Giuseppe

2018-01-01

Knowledge of the biomechanical properties of the human cornea is crucial for understanding the development of corneal diseases and impact of surgical treatments (e.g., corneal laser surgery, corneal cross-linking). Using a Surface Force Apparatus we investigated the transient viscous response of the anterior cornea from donor human eyes compressed between macroscopic crossed cylinders. Corneal biomechanics was analyzed using linear viscoelastic theory and interpreted in the framework of a biphasic model of soft hydrated porous tissues, including a significant contribution from the pressurization and viscous flow of fluid within the corneal tissue. Time-resolved measurements of tissue deformation and careful determination of the relaxation time provided an elastic modulus in the range between 0.17 and 1.43 MPa, and fluid permeability of the order of 10-13 m4/(N∙s). The permeability decreased as the deformation was increased above a strain level of about 10%, indicating that the interstitial space between fibrils of the corneal stromal matrix was reduced under the effect of strong compression. This effect may play a major role in determining the observed rate-dependent non-linear stress-strain response of the anterior cornea, which underlies the shape and optical properties of the tissue.

[Cognitive Function and Calcium. Structures and functions of Ca2+-permeable channels].

PubMed

Kaneko, Shuji

2015-02-01

Calcium is essential for living organisms where the increase in intracellular Ca2+ concentration functions as a second messenger for many cellular processes including synaptic transmission and neural plasticity. The cytosolic concentration of Ca2+ is finely controlled by many Ca2+-permeable ion channels and transporters. The comprehensive view of their expression, function, and regulation will advance our understanding of neural and cognitive functions of Ca2+, which leads to the future drug discovery.

An investigation of microstructural characteristics of contact-lens polymers

NASA Technical Reports Server (NTRS)

Singh, Jag J.; Eftekhari, Abe; Upchurch, Billy T.; Burns, Karen S.

1990-01-01

The free volume and gas permeability in several contact lens specimens were measured as part of a Space Commercialization Program. Free volume was measured using positron lifetime spectroscopy, while permeability for O2, N2, CO2 gases was measured using mass spectrometry and polarography. Permeability for all gases increases with the mean free volume cell size in the test samples. As might be expected, the specimens with the highest free volume fraction also exhibit the lowest Rockwell Hardness Number. An interesting corollary is the finding that the presence of fluorine atoms in the lens chemical structure inhibits filling up of their free volume cells. This is expected to allow the lenses to breathe freely while in actual use.

Change in permeability of the plasma membrane of blood cells in irradiated animals

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

Shevchenko, A.S.; Kobyalko, V.O.; Lazarev, N.M.

1994-11-01

The Chernobyl nuclear disaster showed the exposure of the thyroid gland to radioactive iodine is an important factor of radiation damage to animals. Examination of domestic animals showed a marked inhibition of thyroid hormone secretion and changes in red cell membrane permeability for calcium in the absence of marked hematological shifts. At the same time the disturbed thyroid statis is associated with changes in some structural and functional parameters of blood cells. This research on calves shows that radiation damage to the thyroid produces a modifying effect on blood cell membrane permeability for calcium during both the acute and latemore » periods following exposure to 131I. 15 refs., 2 figs., 1 tab.« less

Assessment of blood-brain barrier penetration: in silico, in vitro and in vivo.

PubMed

Feng, Meihua Rose

2002-12-01

The amount of drug achieved and maintained in the brain after systemic administration is determined by the agent's permeability at blood-brain barrier (BBB), potential involvement of transport systems, and the distribution, metabolism and elimination properties. Passive diffusion permeability may be predicted by an in silico method based on a molecule's structure property. In vitro cell culture is another useful tool for the assessment of passive permeability and BBB transports (e.g. PGP, MRP). In situ or in vivo techniques like carotid artery single injection or perfusion, brain microdialysis, autoradiography, and others are used at various stages of drug discovery and development to estimate CNS penetration and PK/PD correlation. Each technique has its own application with specific advantages and limitations.

Permeability optimization and performance evaluation of hot aerosol filters made using foam incorporated alumina suspension.

PubMed

Innocentini, Murilo D M; Rodrigues, Vanessa P; Romano, Roberto C O; Pileggi, Rafael G; Silva, Gracinda M C; Coury, José R

2009-02-15

Porous ceramic samples were prepared from aqueous foam incorporated alumina suspension for application as hot aerosol filtering membrane. The procedure for establishment of membrane features required to maintain a desired flow condition was theoretically described and experimental work was designed to prepare ceramic membranes to meet the predicted criteria. Two best membranes, thus prepared, were selected for permeability tests up to 700 degrees C and their total and fractional collection efficiencies were experimentally evaluated. Reasonably good performance was achieved at room temperature, while at 700 degrees C, increased permeability was obtained with significant reduction in collection efficiency, which was explained by a combination of thermal expansion of the structure and changes in the gas properties.

A catalog of porosity and permeability from core plugs in siliciclastic rocks

USGS Publications Warehouse

Nelson, Philip H.; Kibler, Joyce E.

2003-01-01

Porosity and permeability measurements on cored samples from siliciclastic formations are presented for 70 data sets, taken from published data and descriptions. Data sets generally represent specific formations, usually from a limited number of wells. Each data set is represented by a written summary, a plot of permeability versus porosity, and a digital file of the data. The summaries include a publication reference, the geologic age of the formation, location, well names, depth range, various geologic descriptions, and core measurement conditions. Attributes such as grain size or depositional environment are identified by symbols on the plots. An index lists the authors and date, geologic age, formation name, sandstone classification, location, basin or structural province, and field name.

Physically based model for extracting dual permeability parameters using non-Newtonian fluids

NASA Astrophysics Data System (ADS)

Abou Najm, M. R.; Basset, C.; Stewart, R. D.; Hauswirth, S.

2017-12-01

Dual permeability models are effective for the assessment of flow and transport in structured soils with two dominant structures. The major challenge to those models remains in the ability to determine appropriate and unique parameters through affordable, simple, and non-destructive methods. This study investigates the use of water and a non-Newtonian fluid in saturated flow experiments to derive physically-based parameters required for improved flow predictions using dual permeability models. We assess the ability of these two fluids to accurately estimate the representative pore sizes in dual-domain soils, by determining the effective pore sizes of macropores and micropores. We developed two sub-models that solve for the effective macropore size assuming either cylindrical (e.g., biological pores) or planar (e.g., shrinkage cracks and fissures) pore geometries, with the micropores assumed to be represented by a single effective radius. Furthermore, the model solves for the percent contribution to flow (wi) corresponding to the representative macro and micro pores. A user-friendly solver was developed to numerically solve the system of equations, given that relevant non-Newtonian viscosity models lack forms conducive to analytical integration. The proposed dual-permeability model is a unique attempt to derive physically based parameters capable of measuring dual hydraulic conductivities, and therefore may be useful in reducing parameter uncertainty and improving hydrologic model predictions.

Multivariate Geostatistical Analysis of Uncertainty for the Hydrodynamic Model of a Geological Trap for Carbon Dioxide Storage. Case study: Multilayered Geological Structure Vest Valcele, ROMANIA

NASA Astrophysics Data System (ADS)

Scradeanu, D.; Pagnejer, M.

2012-04-01

The purpose of the works is to evaluate the uncertainty of the hydrodynamic model for a multilayered geological structure, a potential trap for carbon dioxide storage. The hydrodynamic model is based on a conceptual model of the multilayered hydrostructure with three components: 1) spatial model; 2) parametric model and 3) energy model. The necessary data to achieve the three components of the conceptual model are obtained from: 240 boreholes explored by geophysical logging and seismic investigation, for the first two components, and an experimental water injection test for the last one. The hydrodinamic model is a finite difference numerical model based on a 3D stratigraphic model with nine stratigraphic units (Badenian and Oligocene) and a 3D multiparameter model (porosity, permeability, hydraulic conductivity, storage coefficient, leakage etc.). The uncertainty of the two 3D models was evaluated using multivariate geostatistical tools: a)cross-semivariogram for structural analysis, especially the study of anisotropy and b)cokriging to reduce estimation variances in a specific situation where is a cross-correlation between a variable and one or more variables that are undersampled. It has been identified important differences between univariate and bivariate anisotropy. The minimised uncertainty of the parametric model (by cokriging) was transferred to hydrodynamic model. The uncertainty distribution of the pressures generated by the water injection test has been additional filtered by the sensitivity of the numerical model. The obtained relative errors of the pressure distribution in the hydrodynamic model are 15-20%. The scientific research was performed in the frame of the European FP7 project "A multiple space and time scale approach for the quantification of deep saline formation for CO2 storage(MUSTANG)".

Depth-Dependent Permeability and Heat Output at Basalt-Hosted Hydrothermal Systems Across Mid-Ocean Ridge Spreading Rates

NASA Astrophysics Data System (ADS)

Barreyre, Thibaut; Olive, Jean-Arthur; Crone, Timothy J.; Sohn, Robert A.

2018-04-01

The permeability of the oceanic crust exerts a primary influence on the vigor of hydrothermal circulation at mid-ocean ridges, but it is a difficult to measure parameter that varies with time, space, and geological setting. Here we develop an analytical model for the poroelastic response of hydrothermal exit-fluid velocities and temperatures to ocean tidal loading in a two-layered medium to constrain the discharge zone permeability of each layer. The top layer, corresponding to extrusive lithologies (e.g., seismic layer 2A) overlies a lower permeability layer, corresponding to intrusive lithologies (e.g., layer 2B). We apply the model to three basalt-hosted hydrothermal fields (i.e., Lucky Strike, Main Endeavour and 9°46'N L-vent) for which the seismic stratigraphy is well-established, and for which robust exit-fluid temperature data are available. We find that the poroelastic response to tidal loading is primarily controlled by layer 2A permeability, which is about 3 orders of magnitude higher for the Lucky Strike site (˜10-10 m2) than the 9°46'N L-vent site (˜10-13 m2). By contrast, layer 2B permeability does not exert a strong control on the poroelastic response to tidal loading, yet strongly modulates the heat output of hydrothermal discharge zones. Taking these constraints into account, we estimate a plausible range of layer 2B permeability between ˜10-15 m2 and an upper-bound value of ˜10-14 (9°46'N L-vent) to ˜10-12 m2 (Lucky Strike). These permeability structures reconcile the short-term response and long-term thermal output of hydrothermal sites, and provide new insights into the links between permeability and tectono-magmatic processes along the global mid-ocean ridge.

Permeability and microstructural changes due to weathering of pyroclastic rocks in Cappadocia, central Turkey

NASA Astrophysics Data System (ADS)

Sato, M.; Takahashi, M.; Anma, R.; Shiomi, K.

2014-12-01

Studies of permeability changes of rocks during weathering are important to understand the processes of geomorphological development and how they are influenced by cyclic climatic conditions. Especially volcanic tuffs and pyroclastic flow deposits are easily affected by water absorption and freezing-thawing cycle (Erguler. 2009, Çelik and Ergül 2014). Peculiar erosional landscapes of Cappadocia, central Turkey, with numerous underground cities and carved churches, that made this area a world heritage site, are consists of volcanic tuffs and pyroclastic flow deposits. Understanding permeability changes of such rocks under different conditions are thus important not only to understand fundamental processes of weathering, but also to protect the landscapes of the world heritage sites and archaeological remains. In this study, we aim to evaluate internal void structures and bulk permeability of intact and weathered pyroclastic rocks from Cappadocia using X-ray CT, mercury intrusion porosimetry data and permeability measurement method of flow pump test. Samples of pyroclastic deposits that comprise the landscapes of Rose Valley and Ihlara Valley, were collected from the corresponding strata outside of the preservation areas. Porosity and pore-size distribution for the same samples measured by mercury intrusion porosimetry, indicate that the intact samples have lower porosity than weathered samples and pore sizes were dominantly 1-10μm in calculated radii, whereas weathered samples have more micropores (smaller than 1 μm). X-ray CT images were acquired to observe internal structure of samples. Micro-fractures, probably caused by repeated expansion and contraction due to temperature changes, were observed around clast grains. The higher micropore ratio in weathered samples could be attributed to the development of the micro-farctures. We will discuss fundamental processes of weathering and geomorphological development models using these data.

A combined numerical and experimental framework for determining permeability properties of the arterial media.

PubMed

Comerford, A; Chooi, K Y; Nowak, M; Weinberg, P D; Sherwin, S J

2015-04-01

The medial layer of the arterial wall may play an important role in the regulation of water and solute transport across the wall. In particular, a high medial resistance to transport could cause accumulation of lipid-carrying molecules in the inner wall. In this study, the water transport properties of medial tissue were characterised in a numerical model, utilising experimentally obtained data for the medial microstructure and the relative permeability of different constituents. For the model, a new solver for flow in porous materials, based on a high-order splitting scheme, was implemented in the spectral/hp element library nektar++ and validated. The data were obtained by immersing excised aortic bifurcations in a solution of fluorescent protein tracer and subsequently imaging them with a confocal microscope. Cuboidal regions of interest were selected in which the microstructure and relative permeability of different structures were transformed to a computational mesh. Impermeable objects were treated fictitiously in the numerical scheme. On this cube, a pressure drop was applied in the three coordinate directions and the principal components of the permeability tensor were determined. The reconstructed images demonstrated the arrangement of elastic lamellae and interspersed smooth muscle cells in rat aortic media; the distribution and alignment of the smooth muscle cells varied spatially within the extracellular matrix. The numerical simulations highlighted that the heterogeneity of the medial structure is important in determining local water transport properties of the tissue, resulting in regional and directional variation of the permeability tensor. A major factor in this variation is the alignment and density of smooth muscle cells in the media, particularly adjacent to the adventitial layer.

Investigation on porosity and permeability change of Mount Simon sandstone (Knox County, IN, USA) under geological CO 2 sequestration conditions: a numerical simulation approach

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

Zhang, Liwei; Soong, Yee; Dilmore, Robert M.

In this paper, a numerical model was developed to simulate reactive transport with porosity and permeability change of Mount Simon sandstone (samples from Knox County, IN) after 180 days of exposure to CO 2-saturated brine under CO 2 sequestration conditions. The model predicted formation of a high-porosity zone adjacent to the surface of the sample in contact with bulk brine, and a lower porosity zone just beyond that high-porosity zone along the path from sample/bulk brine interface to sample core. The formation of the high porosity zone was attributed to dissolution of quartz and muscovite/illite, while the formation of themore » lower porosity zone adjacent to the aforementioned high porosity zone was attributed to precipitation of kaolinite and feldspar. The model predicted a 40% permeability increase for the Knox sandstone sample after 180 days of exposure to CO 2-saturated brine, which was consistent with laboratory-measured permeability results. Model-predicted solution chemistry results were also found to be consistent with laboratory-measured solution chemistry data. Finally, initial porosity, initial feldspar content and the exponent n value (determined by pore structure and tortuosity) used in permeability calculations were three important factors affecting permeability evolution of sandstone samples under CO 2 sequestration conditions.« less

Investigation on porosity and permeability change of Mount Simon sandstone (Knox County, IN, USA) under geological CO 2 sequestration conditions: a numerical simulation approach

DOE PAGES

Zhang, Liwei; Soong, Yee; Dilmore, Robert M.

2016-01-14

In this paper, a numerical model was developed to simulate reactive transport with porosity and permeability change of Mount Simon sandstone (samples from Knox County, IN) after 180 days of exposure to CO 2-saturated brine under CO 2 sequestration conditions. The model predicted formation of a high-porosity zone adjacent to the surface of the sample in contact with bulk brine, and a lower porosity zone just beyond that high-porosity zone along the path from sample/bulk brine interface to sample core. The formation of the high porosity zone was attributed to dissolution of quartz and muscovite/illite, while the formation of themore » lower porosity zone adjacent to the aforementioned high porosity zone was attributed to precipitation of kaolinite and feldspar. The model predicted a 40% permeability increase for the Knox sandstone sample after 180 days of exposure to CO 2-saturated brine, which was consistent with laboratory-measured permeability results. Model-predicted solution chemistry results were also found to be consistent with laboratory-measured solution chemistry data. Finally, initial porosity, initial feldspar content and the exponent n value (determined by pore structure and tortuosity) used in permeability calculations were three important factors affecting permeability evolution of sandstone samples under CO 2 sequestration conditions.« less

Effect of plasma nitriding on the structural stability and hydrogen absorption capability of Pd-coated Nb during thermal treatment

NASA Astrophysics Data System (ADS)

Ohtsu, Naofumi; Kozuka, Taro; Shibata, Yuga; Yamane, Misao

2017-11-01

Plasma nitriding was explored for improving the thermal stability of a composite hydrogen permeable membrane comprising a Pd coating on Nb substrate. A NbN intermediate layer was formed on the Nb substrate, and the progress of interdiffusion and deterioration of hydrogen absorption behavior after a thermal treatment at 573 and 773 K, respectively, were investigated. The intermediate layer significantly suppressed the interdiffusion between the coating and the substrate. Furthermore, an increase in the NbN concentration of the intermediate layer enhanced the suppression efficiency. However, the hydrogen permeability of the intermediate layer was significantly low, and hence, an increase in NbN concentration further decreased the hydrogen permeability. We concluded that the nitride layer with a high NbN content was unsuitable as an intermediate layer owing to its low hydrogen permeability, while the partial nitride layer with a low NbN content was inefficient in suppressing the interdiffusion.

Broadband complex permeability characterization of magnetic thin films using shorted microstrip transmission-line perturbation

NASA Astrophysics Data System (ADS)

Liu, Yan; Chen, Linfeng; Tan, C. Y.; Liu, H. J.; Ong, C. K.

2005-06-01

A brief review of the methods used for broadband complex permeability measurement of magnetic thin films up to microwave frequencies is given. In particular, the working principles of the transmission-line perturbation methods for the characterization of magnetic thin films are discussed, with emphasis on short-circuited planar transmission-line perturbation methods. The algorithms for calculating the complex permeability of magnetic thin films for short-circuited planar transmission-line perturbation methods are analyzed. A shorted microstrip line is designed and fabricated as a prototype measurement fixture. The structure of the microstrip fixture and the corresponding measurement procedure are discussed in detail. A piece of 340 nm thick FeTaN thin film deposited on Si substrate using sputtering method is characterized using the microstrip fixture. An improved technique for obtaining permeability by using a saturation magnetization field is demonstrated here, and the results fit well with the Landau-Lifchitz-Gilbert theory. Approaches to extending this method to other aspects in the investigation of magnetic thin film are also discussed.

Effects of lamination and coating with drying oils on tensile and barrier properties of zein films.

PubMed

Rakotonirainy, A M; Padua, G W

2001-06-01

Zein films plasticized with oleic acid have been considered potentially useful for biodegradable packaging applications. However, moisture was found to affect their tensile and gas barrier properties. We investigated the effects of two converting processes, fusion lamination and coating with drying oils, on tensile properties and gas permeability of zein films. Zein films were laminated to 4-ply sheets in a Carver press and coated with tung oil, linseed oil, or a mixture of tung and soybean oils. Tensile properties and permeability to water vapor, oxygen, and carbon dioxide were measured according to ASTM methods. Laminated films were clearer, tougher, and more flexible, and had a smoother finish than nontreated sheets. Lamination decreased O(2) and CO(2) permeability by filling in voids and pinholes in the film structure. Coating increased tensile strength and elongation and decreased water vapor permeability. Coatings acted as a composite layer preventing crack propagation and increasing film strength. They also formed a highly hydrophobic surface that prevented film wetting.

Mean-field model of the von Kármán sodium dynamo experiment using soft iron impellers.

PubMed

Nore, C; Léorat, J; Guermond, J-L; Giesecke, A

2015-01-01

It has been observed that dynamo action occurs in the von-Kármán-Sodium (VKS) experiment only when the rotating disks and the blades are made of soft iron. The purpose of this paper is to numerically investigate the role of soft iron in the VKS dynamo scenario. This is done by using a mean-field model based on an axisymmetric mean flow, a localized permeability distribution, and a localized α effect modeling the action of the small velocity scales between the blades. The action of the rotating blades is modeled by an axisymmetric effective permeability field. Key properties of the flow giving to the numerical magnetic field a geometric structure similar to that observed experimentally are identified. Depending on the permeability of the disks and the effective permeability of the blades, the dynamo that is obtained is either oscillatory or stationary. Our numerical results confirm the leading role played by the ferromagnetic impellers. A scenario for the VKS dynamo is proposed.

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

Raduha, S.; Butler, D.; Mozley, P. S.

Here, we examined the potential impact on CO 2 transport of zones of deformation bands in reservoir rock that transition to opening-mode fractures within overlying caprock. Sedimentological and petrophysical measurements were collected along an approximately 5 m × 5 m outcrop of the Slick Rock and Earthy Members of the Entrada Sandstone on the eastern flank of the San Rafael Swell, Utah, USA. Measured deformation band permeability (2 mD) within the reservoir facies is about three orders of magnitude lower than the host sandstone. Average permeability of the caprock facies (0.0005 mD) is about seven orders of magnitude lower thanmore » the host sandstone. Aperture-based permeability estimates of the opening-mode caprock fractures are high (3.3 × 10 7 mD). High-resolution CO 2–H 2O transport models incorporate these permeability data at the millimeter scale. We then varied fault properties at the reservoir/caprock interface between open fractures and deformation bands as part of a sensitivity study. Numerical modeling results suggest that zones of deformation bands within the reservoir strongly compartmentalize reservoir pressures largely blocking lateral, cross-fault flow of supercritical CO 2. Significant vertical CO 2 transport into the caprock occurred in some scenarios along opening-mode fractures. The magnitude of this vertical CO 2 transport depends on the small-scale geometry of the contact between the opening-mode fracture and the zone of deformation bands, as well as the degree to which fractures penetrate caprock. Finally, the presence of relatively permeable units within the caprock allows storage of significant volumes of CO 2, particularly when the fracture network does not extend all the way through the caprock.« less

A method to predict different mechanisms for blood-brain barrier permeability of CNS activity compounds in Chinese herbs using support vector machine.

PubMed

Jiang, Ludi; Chen, Jiahua; He, Yusu; Zhang, Yanling; Li, Gongyu

2016-02-01

The blood-brain barrier (BBB), a highly selective barrier between central nervous system (CNS) and the blood stream, restricts and regulates the penetration of compounds from the blood into the brain. Drugs that affect the CNS interact with the BBB prior to their target site, so the prediction research on BBB permeability is a fundamental and significant research direction in neuropharmacology. In this study, we combed through the available data and then with the help of support vector machine (SVM), we established an experiment process for discovering potential CNS compounds and investigating the mechanisms of BBB permeability of them to advance the research in this field four types of prediction models, referring to CNS activity, BBB permeability, passive diffusion and efflux transport, were obtained in the experiment process. The first two models were used to discover compounds which may have CNS activity and also cross the BBB at the same time; the latter two were used to elucidate the mechanism of BBB permeability of those compounds. Three optimization parameter methods, Grid Search, Genetic Algorithm (GA), and Particle Swarm Optimization (PSO), were used to optimize the SVM models. Then, four optimal models were selected with excellent evaluation indexes (the accuracy, sensitivity and specificity of each model were all above 85%). Furthermore, discrimination models were utilized to study the BBB properties of the known CNS activity compounds in Chinese herbs and this may guide the CNS drug development. With the relatively systematic and quick approach, the application rationality of traditional Chinese medicines for treating nervous system disease in the clinical practice will be improved.

Multiscale fracture network characterization and impact on flow: A case study on the Latemar carbonate platform

NASA Astrophysics Data System (ADS)

Hardebol, N. J.; Maier, C.; Nick, H.; Geiger, S.; Bertotti, G.; Boro, H.

2015-12-01

A fracture network arrangement is quantified across an isolated carbonate platform from outcrop and aerial imagery to address its impact on fluid flow. The network is described in terms of fracture density, orientation, and length distribution parameters. Of particular interest is the role of fracture cross connections and abutments on the effective permeability. Hence, the flow simulations explicitly account for network topology by adopting Discrete-Fracture-and-Matrix description. The interior of the Latemar carbonate platform (Dolomites, Italy) is taken as outcrop analogue for subsurface reservoirs of isolated carbonate build-ups that exhibit a fracture-dominated permeability. New is our dual strategy to describe the fracture network both as deterministic- and stochastic-based inputs for flow simulations. The fracture geometries are captured explicitly and form a multiscale data set by integration of interpretations from outcrops, airborne imagery, and lidar. The deterministic network descriptions form the basis for descriptive rules that are diagnostic of the complex natural fracture arrangement. The fracture networks exhibit a variable degree of multitier hierarchies with smaller-sized fractures abutting against larger fractures under both right and oblique angles. The influence of network topology on connectivity is quantified using Discrete-Fracture-Single phase fluid flow simulations. The simulation results show that the effective permeability for the fracture and matrix ensemble can be 50 to 400 times higher than the matrix permeability of 1.0 · 10-14 m2. The permeability enhancement is strongly controlled by the connectivity of the fracture network. Therefore, the degree of intersecting and abutting fractures should be captured from outcrops with accuracy to be of value as analogue.

Potential seal bypass and caprock storage produced by deformation-band-to-opening-mode-fracture transition at the reservoir/caprock interface

DOE PAGES

Raduha, S.; Butler, D.; Mozley, P. S.; ...

2016-06-18

Here, we examined the potential impact on CO 2 transport of zones of deformation bands in reservoir rock that transition to opening-mode fractures within overlying caprock. Sedimentological and petrophysical measurements were collected along an approximately 5 m × 5 m outcrop of the Slick Rock and Earthy Members of the Entrada Sandstone on the eastern flank of the San Rafael Swell, Utah, USA. Measured deformation band permeability (2 mD) within the reservoir facies is about three orders of magnitude lower than the host sandstone. Average permeability of the caprock facies (0.0005 mD) is about seven orders of magnitude lower thanmore » the host sandstone. Aperture-based permeability estimates of the opening-mode caprock fractures are high (3.3 × 10 7 mD). High-resolution CO 2–H 2O transport models incorporate these permeability data at the millimeter scale. We then varied fault properties at the reservoir/caprock interface between open fractures and deformation bands as part of a sensitivity study. Numerical modeling results suggest that zones of deformation bands within the reservoir strongly compartmentalize reservoir pressures largely blocking lateral, cross-fault flow of supercritical CO 2. Significant vertical CO 2 transport into the caprock occurred in some scenarios along opening-mode fractures. The magnitude of this vertical CO 2 transport depends on the small-scale geometry of the contact between the opening-mode fracture and the zone of deformation bands, as well as the degree to which fractures penetrate caprock. Finally, the presence of relatively permeable units within the caprock allows storage of significant volumes of CO 2, particularly when the fracture network does not extend all the way through the caprock.« less

Interaction of Vortex Rings and Steady Jets with Permeable Screens of Varied Porosity

NASA Astrophysics Data System (ADS)

Musta, Mustafa

2013-11-01

Vortex ring and steady jet interaction with a porous matrix formed from several parallel, transparent permeable screens with the same grid geometry for open area ratios (φ) 49.5% - 83.8% was studied previously using digital particle image velocimetry (DPIV) at jet Reynolds number (Re) of 1000-3000. Vortex ring results showed that unlike the experiments with thin screens, a transmitted vortex ring, which has a similar diameter to the primary one, wasn't formed. Instead a centerline vortex ring like structure formed and its diameter, circulation, and dissipation time decreased as φ decreased. However, for the case of screens φ = 55.7% with large screen spacing, reformation of large scale weak vortex rings was observed downstream of the first screen. The present work experimentally investigates the interaction of vortex rings and steady jets with screens of decreasing φ (83.8%-49.5%) in the flow direction. A piston type vortex ring generator was used and measurements were made using DPIV. The vortex ring results show that the size and circulation of the vortex ring like flow structure was changed based on the screen φ within the permeable screen matrix. Similarly, steady jet flow structure and the local turbulent kinetic energy was changed based on the local screen φ.

Crystal Structure of an Ammonia-Permeable Aquaporin

PubMed Central

Kirscht, Andreas; Kaptan, Shreyas S.; Bienert, Gerd Patrick; Chaumont, François; Nissen, Poul; de Groot, Bert L.; Kjellbom, Per; Gourdon, Pontus; Johanson, Urban

2016-01-01

Aquaporins of the TIP subfamily (Tonoplast Intrinsic Proteins) have been suggested to facilitate permeation of water and ammonia across the vacuolar membrane of plants, allowing the vacuole to efficiently sequester ammonium ions and counteract cytosolic fluctuations of ammonia. Here, we report the structure determined at 1.18 Å resolution from twinned crystals of Arabidopsis thaliana aquaporin AtTIP2;1 and confirm water and ammonia permeability of the purified protein reconstituted in proteoliposomes as further substantiated by molecular dynamics simulations. The structure of AtTIP2;1 reveals an extended selectivity filter with the conserved arginine of the filter adopting a unique unpredicted position. The relatively wide pore and the polar nature of the selectivity filter clarify the ammonia permeability. By mutational studies, we show that the identified determinants in the extended selectivity filter region are sufficient to convert a strictly water-specific human aquaporin into an AtTIP2;1-like ammonia channel. A flexible histidine and a novel water-filled side pore are speculated to deprotonate ammonium ions, thereby possibly increasing permeation of ammonia. The molecular understanding of how aquaporins facilitate ammonia flux across membranes could potentially be used to modulate ammonia losses over the plasma membrane to the atmosphere, e.g., during photorespiration, and thereby to modify the nitrogen use efficiency of plants. PMID:27028365

Three-Dimensional Microphase Separation and Synergistic Permeability in Stacked Lipid–Polymer Hybrid Membranes

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

Kang, Minjee; Lee, Byeongdu; Leal, Cecilia

Here, we present new structures of soft-material thin films that augment the functionality of substrate-mediated delivery systems. A hybrid material composed of phospholipids and block copolymers adopts a multilayered membrane structure supported on a solid surface. The hybrid films comprise intentional intramembrane heterogeneities that register across multilayers. These stacked domains convey unprecedented enhancement and control of permeability of solutes across micrometer-thick films. Using grazing incidence X-ray scattering, phase contrast atomic force microscopy, and confocal microscopy, we observed that in each lamella, lipid and polymers partition unevenly within the membrane plane segregating into lipid- or polymer-rich domains. Interestingly, we found evidencemore » that like-domains align in registry across multilayers, thereby making phase separation three-dimensional. Phase boundaries exist over extended length scales to compensate the height mismatch between lipid and polymer molecules. We show that microphase separation in hybrid films can be exploited to augment the capability of drug-eluting substrates. Lipid–polymer hybrid films loaded with paclitaxel show synergistic permeability of drug compared to single-component counterparts. We present a thorough structural study of stacked lipid–polymer hybrid membranes and propose that the presence of registered domains and domain boundaries impart enhanced drug release functionality. This work offers new perspectives in designing thin films for controlled delivery applications« less

Three-Dimensional Microphase Separation and Synergistic Permeability in Stacked Lipid–Polymer Hybrid Membranes

DOE PAGES

Kang, Minjee; Lee, Byeongdu; Leal, Cecilia

2017-10-20

Here, we present new structures of soft-material thin films that augment the functionality of substrate-mediated delivery systems. A hybrid material composed of phospholipids and block copolymers adopts a multilayered membrane structure supported on a solid surface. The hybrid films comprise intentional intramembrane heterogeneities that register across multilayers. These stacked domains convey unprecedented enhancement and control of permeability of solutes across micrometer-thick films. Using grazing incidence X-ray scattering, phase contrast atomic force microscopy, and confocal microscopy, we observed that in each lamella, lipid and polymers partition unevenly within the membrane plane segregating into lipid- or polymer-rich domains. Interestingly, we found evidencemore » that like-domains align in registry across multilayers, thereby making phase separation three-dimensional. Phase boundaries exist over extended length scales to compensate the height mismatch between lipid and polymer molecules. We show that microphase separation in hybrid films can be exploited to augment the capability of drug-eluting substrates. Lipid–polymer hybrid films loaded with paclitaxel show synergistic permeability of drug compared to single-component counterparts. We present a thorough structural study of stacked lipid–polymer hybrid membranes and propose that the presence of registered domains and domain boundaries impart enhanced drug release functionality. This work offers new perspectives in designing thin films for controlled delivery applications« less

In Situ Measurement of Permeability in the Vicinity of Faulted Nonwelded Bishop Tuff, Bishop, CA

NASA Astrophysics Data System (ADS)

Dinwiddie, C. L.; Fedors, R. W.; Ferrill, D. A.; Bradbury, K. K.

2002-12-01

The nonwelded Bishop Tuff includes matrix-supported massive ignimbrites and clast-supported bedded deposits. Fluid flow through such faulted nonwelded tuff is likely to be influenced by a combination of host rock properties and the presence of deformation features, such as open fractures, mineralized fractures, and fault zones that exhibit comminuted fault rock and clays. Lithologic contacts between fine- and coarse-grained sub-units of nonwelded tuff may induce formation of capillary and/or permeability barriers within the unsaturated zone, potentially leading to down-dip lateral diversion of otherwise vertically flowing fluid. However, discontinuities (e.g., fractures and faults) may lead to preferential sub-vertical fast flow paths in the event of episodic infiltration rates, thus disrupting the potential for both (1) large-scale capillary and/or permeability barriers to form and for (2) redirection of water flow over great lateral distances. This study focuses on an innovative technique for measuring changes in matrix permeability near faults in situ--changes that may lead to enhancement of vertical fluid flow and disruption of lateral fluid flow. A small-drillhole minipermeameter probe provides a means to eliminate extraction of fragile nonwelded tuffs as a necessity for permeability measurement. Advantages of this approach include (1) a reduction of weathering-effects on measured permeability, and (2) provision of a superior sealing mechanism around the gas injection zone. In order to evaluate the effect of faults and fault zone deformation on nonwelded tuff matrix permeability, as well as to address the potential for disruption of lithologic barrier-induced lateral diversion of flow, data were collected from two fault systems and from unfaulted host rock. Two hundred and sixty-seven gas-permeability measurements were made at 89 locations; i.e. permeability measurements were made in triplicate at each location with three flow rates. Data were collected at the first fault and perpendicularly away from it within the hanging wall to a distance of 6 m [20 ft] along one transect, and perpendicular to the fault from the foot wall to the hanging wall for a distance of 6 m [20 ft] along a second transect. Additionally, eight water-permeameter tests were conducted in order to augment the gas-permeability data. Gas-permeability measurements were collected along two transects at the main fault of the second fault system and perpendicularly away from it within the foot wall to a distance of 10.5 m [34 ft], crossing several secondary faults in the process. Data were also collected within the fault gouge of the main fault, and were found to vary therein by an order of magnitude. This Bishop Tuff study supports the U.S. Nuclear Regulatory Commission (NRC) review of hydrologic property studies at Yucca Mountain, Nevada, which are conducted by the U.S. Department of Energy. This abstract is an independent product of the CNWRA and does not necessarily reflect the views or regulatory position of the NRC.

Effect of film multi-scale structure on the water vapor permeability in hydroxypropyl starch (HPS)/Na-MMT nanocomposites.

PubMed

Liu, Siyuan; Cai, Panfu; Li, Xiaoxi; Chen, Ling; Li, Lin; Li, Bing

2016-12-10

To improve the water vapor resistance of starch-based films, Na-MMT (Na-montmorillonite) as nanofillers were fabricated into hydroxypropyl starch and the multi-scale structural changes (including intermolecular interaction, short-range conformation, long-range ordered structure and the aggregated structure of the film) were revealed. The elongation of the water vapor molecule pathway by tortuous path is generally recognized as the main reason for the improvement of water resistance. However this study observed the lowest water vapor permeability (WVP) was at the 3% Na-MMT/hydroxypropyl starch (HPS) ratio instead of 5% even nanofillers were partially exfoliated at both ratio. Except for the "tortuous path" caused by nanofillers, this observation proposed that the short-range conformation of HPS chains, long-range ordered structure and the aggregated structure likely influenced the water barrier property. The relationship between WVP and multi-scale structure of the film was investigated. The results suggested that a good balance of short-range conformationin the amorphous region, long-range ordered structure and the aggregated structure of the film was required for the improvement of water vapor barrier property. Copyright © 2016 Elsevier Ltd. All rights reserved.

Geometrical analysis of woven fabric microstructure based on micron-resolution computed tomography data

NASA Astrophysics Data System (ADS)

Krieger, Helga; Seide, Gunnar; Gries, Thomas; Stapleton, Scott E.

2018-04-01

The global mechanical properties of textiles such as elasticity and strength, as well as transport properties such as permeability depend strongly on the microstructure of the textile. Textiles are heterogeneous structures with highly anisotropic material properties, including local fiber orientation and local fiber volume fraction. In this paper, an algorithm is presented to generate a virtual 3D-model of a woven fabric architecture with information about the local fiber orientation and the local fiber volume fraction. The geometric data of the woven fabric impregnated with resin was obtained by micron-resolution computed tomography (μCT). The volumetric μCT-scan was discretized into cells and the microstructure of each cell was analyzed and homogenized. Furthermore, the discretized data was used to calculate the local permeability tensors of each cell. An example application of the analyzed data is the simulation of the resin flow through a woven fabric based on the determined local permeability tensors and on Darcy's law. The presented algorithm is an automated and robust method of going from μCT-scans to structural or flow models.

A sedimentological approach to hydrologic characterization: A detailed three-dimensional study of an outcrop of the Sierra Ladrones Formation, Albuquerque basin

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

Lohmann, R.C.

1992-01-01

Three-dimensional geologic outcrop studies which quantitatively describe the geologic architecture of deposits of a specific depositional environment are a necessary requirement for characterization of the permeability structure of an aquifer. The objective of this study is to address this need for quantitative, three-dimensional outcrop studies. For this study, a 10,000 m{sup 2} by 25 m high outcrop of Pliocene-Pleistocene Sierra Ladrones Formation located near Belen, New Mexico was mapped in detail, and the geologic architecture was quantified using geostatistical variogram analysis. In general, the information contained in this study should be useful for hydrologists working on the characterization of aquifersmore » from similar depositional environments such as this one. However, for the permeability correlation study to be truly useful, the within-element correlation structure needs to be superimposed on the elements themselves instead of using mean log (k) values, as was done for this study. Such information is derived from outcrop permeability sampling such as the work of Davis (1990) and Goggin et al. (1988).« less

Micelle-template synthesis of hollow silica spheres for improving water vapor permeability of waterborne polyurethane membrane

PubMed Central

Bao, Yan; Wang, Tong; Kang, Qiaoling; Shi, Chunhua; Ma, Jianzhong

2017-01-01

Hollow silica spheres (HSS) with special interior spaces, high specific surface area and excellent adsorption and permeability performance were synthesized via micelle-template method using cetyl trimethyl ammonium bromide (CTAB) micelles as soft template and tetraethoxysilane (TEOS) as silica precursor. SEM, TEM, FT-IR, XRD, DLS and BET-BJH were carried out to characterize the morphology and structure of as-obtained samples. The results demonstrated that the samples were amorphous with a hollow structure and huge specific surface area. The growth of HSS was an inward-growth mechanism along template. Notably, we have provided a new and interesting fundamental principle for HSS materials by precisely controlling the ethanol-to-water volume ratio. In addition, the as-obtained HSS were mixed with waterborne polyurethane (WPU) to prepare WPU/HSS composite membrane. Various characterizations (SEM, TEM, FT-IR and TGA) revealed the morphology, polydispersity and adherence between HSS and WPU. Performance tests showed that the introduction of HSS can improve the water vapor permeability of composite membrane, promoting its water resistance and mechanical performance at the same time. PMID:28429740

Role of crystal orientation on electrical tuning of dynamic permeability in strain-mediated multiferroic structures

NASA Astrophysics Data System (ADS)

Phuoc, Nguyen N.; Ong, C. K.

2017-06-01

Multiferroic structures of FeCo/NiFe/[Pb(Mg1/3Nb2/3)O3]0.68-[PbTiO3]0.32 (PMN-PT) with three different crystal orientations of PMN-PT(0 1 1), PMN-PT(0 0 1) and PMN-PT(1 1 1) were fabricated by a sputtering deposition system. Their dynamic magnetic properties were characterized under various applied electrical fields. The sample with PMN-PT(0 1 1) orientation shows a large tuning of the permeability spectra while the ones with PMN-PT(0 0 1) and PMN-PT(1 1 1) orientations exhibit a moderate and little change in the permeability spectra, respectively. The result can be explained via the magnetoelectric effect by considering the role of the piezoelectric coefficients being highly dependent on the crystal orientation along which the PMN-PT is poled. This explanation is consistent with the static magnetic characteristics of the samples before and after poling.

Studies on increased vascular permeability in the pathogenesis of lesions of connective tissue diseases: I. Experimental hyperlipidaemia and immune arthropathy.

PubMed

Valente, A J; Walton, K W

1980-10-01

In order to investigate the known associations between hyperlipidaemia and various rheumatic complaints, immune arthritis and hyperlipidaemia have been induced concurrently in rabbits. The results obtained show that: (1) Rabbit apolipoprotein B-containing lipoproteins (LpB), which are normally virtually excluded from joint fluid, gain access to the inflamed joint in the serous effusion and serve as intrinsic indicators of altered local permeability to macromolecules. (2) Much of the LpB entering the joint space is taken up by the phagocytic cells and, following intracellular hydrolysis, leaves a lipid residue. In some chronically affected joints these residues are modified so as to give rise to crystalline cholesterol and its esters. Such crystals may serve as a chronic irritant in the joint. (3) In addition intact LpB is found sequestered in the superficial layers of intra-articular collagenous structures of the challenged joint in a distribution identical with that of similarly sequestered immune complexes and complement, suggesting altered permeability of these intra-articular structures also.

Kinetics of doublet formation in bicomponent magnetic suspensions: The role of the magnetic permeability anisotropy

NASA Astrophysics Data System (ADS)

Lopez-Lopez, M. T.; Nogueras-Lara, F.; Rodriguez-Arco, L.; Guigo, N.; Sbirrazzuoli, N.; Zubarev, A. Yu.; Lacis, S.; Kuzhir, P.

2017-12-01

Micron-sized particles (microbeads) dispersed in a suspension of magnetic nanoparticles, i.e., ferrofluids, can be assembled into different types of structures upon application of an external magnetic field. This paper is devoted to theoretical modeling of a relative motion of a pair of microbeads (either soft ferromagnetic or diamagnetic) in the ferrofluid under the action of applied uniform magnetic field which induces magnetic moments in the microbeads making them attracting to each other. The model is based on a point-dipole approximation for the magnetic interactions between microbeads mediated by the ferrofluid; however, the ferrofluid is considered to possess an anisotropic magnetic permeability thanks to field-induced structuring of its nanoparticles. The model is tested against experimental results and shows generally better agreement with experiments than the model considering isotropic magnetic permeability of ferrofluids. The results could be useful for understanding kinetics of aggregation of microbeads suspended in a ferrofluid. From a broader perspective, the present study is believed to contribute to a general understanding of particle behaviors in anisotropic media.

Disruption of the epithelial barrier during intestinal inflammation: Quest for new molecules and mechanisms.

PubMed

Lechuga, Susana; Ivanov, Andrei I

2017-07-01

The intestinal epithelium forms a key protective barrier that separates internal organs from the harmful environment of the gut lumen. Increased permeability of the gut barrier is a common manifestation of different inflammatory disorders contributing to the severity of disease. Barrier permeability is controlled by epithelial adherens junctions and tight junctions. Junctional assembly and integrity depend on fundamental homeostatic processes such as cell differentiation, rearrangements of the cytoskeleton, and vesicle trafficking. Alterations of intestinal epithelial homeostasis during mucosal inflammation may impair structure and remodeling of apical junctions, resulting in increased permeability of the gut barrier. In this review, we summarize recent advances in our understanding of how altered epithelial homeostasis affects the structure and function of adherens junctions and tight junctions in the inflamed gut. Specifically, we focus on the transcription reprogramming of the cell, alterations in the actin cytoskeleton, and junctional endocytosis and exocytosis. We pay special attention to knockout mouse model studies and discuss the relevance of these mechanisms to human gastrointestinal disorders. Copyright © 2017 Elsevier B.V. All rights reserved.

Micelle-template synthesis of hollow silica spheres for improving water vapor permeability of waterborne polyurethane membrane

NASA Astrophysics Data System (ADS)

Bao, Yan; Wang, Tong; Kang, Qiaoling; Shi, Chunhua; Ma, Jianzhong

2017-04-01

Hollow silica spheres (HSS) with special interior spaces, high specific surface area and excellent adsorption and permeability performance were synthesized via micelle-template method using cetyl trimethyl ammonium bromide (CTAB) micelles as soft template and tetraethoxysilane (TEOS) as silica precursor. SEM, TEM, FT-IR, XRD, DLS and BET-BJH were carried out to characterize the morphology and structure of as-obtained samples. The results demonstrated that the samples were amorphous with a hollow structure and huge specific surface area. The growth of HSS was an inward-growth mechanism along template. Notably, we have provided a new and interesting fundamental principle for HSS materials by precisely controlling the ethanol-to-water volume ratio. In addition, the as-obtained HSS were mixed with waterborne polyurethane (WPU) to prepare WPU/HSS composite membrane. Various characterizations (SEM, TEM, FT-IR and TGA) revealed the morphology, polydispersity and adherence between HSS and WPU. Performance tests showed that the introduction of HSS can improve the water vapor permeability of composite membrane, promoting its water resistance and mechanical performance at the same time.

Micelle-template synthesis of hollow silica spheres for improving water vapor permeability of waterborne polyurethane membrane.

PubMed

Bao, Yan; Wang, Tong; Kang, Qiaoling; Shi, Chunhua; Ma, Jianzhong

2017-04-21

Hollow silica spheres (HSS) with special interior spaces, high specific surface area and excellent adsorption and permeability performance were synthesized via micelle-template method using cetyl trimethyl ammonium bromide (CTAB) micelles as soft template and tetraethoxysilane (TEOS) as silica precursor. SEM, TEM, FT-IR, XRD, DLS and BET-BJH were carried out to characterize the morphology and structure of as-obtained samples. The results demonstrated that the samples were amorphous with a hollow structure and huge specific surface area. The growth of HSS was an inward-growth mechanism along template. Notably, we have provided a new and interesting fundamental principle for HSS materials by precisely controlling the ethanol-to-water volume ratio. In addition, the as-obtained HSS were mixed with waterborne polyurethane (WPU) to prepare WPU/HSS composite membrane. Various characterizations (SEM, TEM, FT-IR and TGA) revealed the morphology, polydispersity and adherence between HSS and WPU. Performance tests showed that the introduction of HSS can improve the water vapor permeability of composite membrane, promoting its water resistance and mechanical performance at the same time.

Permeability, porosity, and mineral surface area changes in basalt cores induced by reactive transport of CO2-rich brine

NASA Astrophysics Data System (ADS)

Luhmann, Andrew J.; Tutolo, Benjamin M.; Bagley, Brian C.; Mildner, David F. R.; Seyfried, William E.; Saar, Martin O.

2017-03-01

Four reactive flow-through laboratory experiments (two each at 0.1 mL/min and 0.01 mL/min flow rates) at 150°C and 150 bar (15 MPa) are conducted on intact basalt cores to assess changes in porosity, permeability, and surface area caused by CO2-rich fluid-rock interaction. Permeability decreases slightly during the lower flow rate experiments and increases during the higher flow rate experiments. At the higher flow rate, core permeability increases by more than one order of magnitude in one experiment and less than a factor of two in the other due to differences in preexisting flow path structure. X-ray computed tomography (XRCT) scans of pre- and post-experiment cores identify both mineral dissolution and secondary mineralization, with a net decrease in XRCT porosity of ˜0.7%-0.8% for the larger pores in all four cores. (Ultra) small-angle neutron scattering ((U)SANS) data sets indicate an increase in both (U)SANS porosity and specific surface area (SSA) over the ˜1 nm to 10 µm scale range in post-experiment basalt samples, with differences due to flow rate and reaction time. Net porosity increases from summing porosity changes from XRCT and (U)SANS analyses are consistent with core mass decreases. (U)SANS data suggest an overall preservation of the pore structure with no change in mineral surface roughness from reaction, and the pore structure is unique in comparison to previously published basalt analyses. Together, these data sets illustrate changes in physical parameters that arise due to fluid-basalt interaction in relatively low pH environments with elevated CO2 concentration, with significant implications for flow, transport, and reaction through geologic formations.

The effect of reservoir geometry, injection and production parameters and permeability structure on induced seismicity

NASA Astrophysics Data System (ADS)

Hosseini, S. M.; Goebel, T.; Aminzadeh, F.

2015-12-01

The recent increase in injection induced seismicity (IIS) in previously less seismically active regions highlighted a need for better mitigation strategies and physics-based models of induced seismicity. Previous models of pressure diffusion and fluid flow investigated the change in Coulomb stress as a result of induced pore-pressure perturbations (e.g. Zhang et al., 2013; Keranen et al., 2014; Hornbach et al., 2015; Segall and Lu, 2015). Here, we consider the additional effects of permeability structure, operational parameters and reservoir geometry. We numerically investigate the influence of net fluid injection volumes; linear, radial, and spherical reservoir geometry; as well as reservoir size. The latter can have a substantial effect on changes in Coulomb stress and subsequent induced seismicity. We report on results from two series of model runs, which explored pressure changes caused by wastewater disposal and water flooding. We observed that a typical water flooding operation that includes production wells and injectors has a lower probability of inducing seismicity. Our observations are in agreement with assessment by National Research Council report on induced seismicity (2012). We developed a third suite of models that investigate the effect of permeability structure on injection-induced seismicity. We examine two cases of wastewater disposal in proximity to active faults: 1) in Central Illinois Basin and 2) in central California. In both cases, we observed that the size of the reservoir, presence of faults, and permeability contrast relative to the host rock, strongly influences the pressure changes with distance and time. These pressure changes vary widely but can easily lead to fault instability and seismic activity at up to 10 km distance from the injection well. The results of this study may help to select safe injection sites and operational conditions in order to minimize injection induced seismicity hazard.

Scaling roads and wildlife: The Cinderella principle

USGS Publications Warehouse

Bissonette, J.A.

2002-01-01

It is clear that a reduction in both direct and indirect effects of roads and road networks must be the goal of management agencies. However, increased permeability of roaded landscapes can only be achieved by up-front planning and subsequent mitigative actions. The key is to understand that roads must be made permeable to the movement of animals. More profoundly, ecosystem services, i.e., clean water, clean air, uncontaminated soil, natural landscapes, recreation opportunities, abundant wildlife, and life sustaining ecological processes must not be seriously impacted. In other words, quality of life as measured by ecosystem services should be a major component of the planning process when roads are constructed or improved. Mitigative structures exist to increase permeability of roads. Wildlife overpasses and underpasses, often referred to as ecoducts or green bridges, with associated structures to enable larger animals to exit the road right of way, e.g., earthen escape ramps (BISSONETTE and HAMMER, 2001), various culvert designs for smaller animals including badger pipes and amphibian and reptile tunnels, and fish ladders are but a small sampling of the structures already in place around the world. What is needed is attention to the big picture. Landscapes need to be reconnected and made more permeable. Responsible agencies and organizations need to be aggressive about promoting mitigations and a conservation ethic into road planning. Only with a broad based effort between a concerned public, a database to work from, and a willingness of responsible agencies, will the now very large virtual footprint of roads and road networks be reduced to more closely approximate the physical footprint. By embracing the Cinderella Principle of making the virtual shoe fit more closely the actual physical footprint of roads, we will be able to achieve a closer connection with ecological harmony with its resultant effect of abundant wildlife.

Revisiting Temporal Markov Chains for Continuum modeling of Transport in Porous Media

NASA Astrophysics Data System (ADS)

Delgoshaie, A. H.; Jenny, P.; Tchelepi, H.

2017-12-01

The transport of fluids in porous media is dominated by flow­-field heterogeneity resulting from the underlying permeability field. Due to the high uncertainty in the permeability field, many realizations of the reference geological model are used to describe the statistics of the transport phenomena in a Monte Carlo (MC) framework. There has been strong interest in working with stochastic formulations of the transport that are different from the standard MC approach. Several stochastic models based on a velocity process for tracer particle trajectories have been proposed. Previous studies have shown that for high variances of the log-conductivity, the stochastic models need to account for correlations between consecutive velocity transitions to predict dispersion accurately. The correlated velocity models proposed in the literature can be divided into two general classes of temporal and spatial Markov models. Temporal Markov models have been applied successfully to tracer transport in both the longitudinal and transverse directions. These temporal models are Stochastic Differential Equations (SDEs) with very specific drift and diffusion terms tailored for a specific permeability correlation structure. The drift and diffusion functions devised for a certain setup would not necessarily be suitable for a different scenario, (e.g., a different permeability correlation structure). The spatial Markov models are simple discrete Markov chains that do not require case specific assumptions. However, transverse spreading of contaminant plumes has not been successfully modeled with the available correlated spatial models. Here, we propose a temporal discrete Markov chain to model both the longitudinal and transverse dispersion in a two-dimensional domain. We demonstrate that these temporal Markov models are valid for different correlation structures without modification. Similar to the temporal SDEs, the proposed model respects the limited asymptotic transverse spreading of the plume in two-dimensional problems.

Tidal Fluctuations in a Deep Fault Extending Under the Santa Barbara Channel, California

NASA Astrophysics Data System (ADS)

Garven, G.; Stone, J.; Boles, J. R.

2013-12-01

Faults are known to strongly affect deep groundwater flow, and exert a profound control on petroleum accumulation, migration, and natural seafloor seepage from coastal reservoirs within the young sedimentary basins of southern California. In this paper we focus on major fault structure permeability and compressibility in the Santa Barbara Basin, where unique submarine and subsurface instrumentation provide the hydraulic characterization of faults in a structurally complex system. Subsurface geologic logs, geophysical logs, fluid P-T-X data, seafloor seep discharge patterns, fault mineralization petrology, isotopic data, fluid inclusions, and structural models help characterize the hydrogeological nature of faults in this seismically-active and young geologic terrain. Unique submarine gas flow data from a natural submarine seep area of the Santa Barbara Channel help constrain fault permeability k ~ 30 millidarcys for large-scale upward migration of methane-bearing formation fluids along one of the major fault zones. At another offshore site near Platform Holly, pressure-transducer time-series data from a 1.5 km deep exploration well in the South Ellwood Field demonstrate a strong ocean tidal component, due to vertical fault connectivity to the seafloor. Analytical models from classic hydrologic papers by Jacob-Ferris-Bredehoeft-van der Kamp-Wang can be used to extract large-scale fault permeability and compressibility parameters, based on tidal signal amplitude attenuation and phase shift at depth. For the South Ellwood Fault, we estimate k ~ 38 millidarcys (hydraulic conductivity K~ 3.6E-07 m/s) and specific storage coefficient Ss ~ 5.5E-08 m-1. The tidal-derived hydraulic properties also suggest a low effective porosity for the fault zone, n ~ 1 to 3%. Results of forward modeling with 2-D finite element models illustrate significant lateral propagation of the tidal signal into highly-permeable Monterey Formation. The results have important practical implications for fault characterization, petroleum migration, structural diagenesis, and carbon sequestration.

Calculating the dermal flux of chemicals with OELs based on their molecular structure: An attempt to assign the skin notation.

PubMed

Kupczewska-Dobecka, Małgorzata; Jakubowski, Marek; Czerczak, Sławomir

2010-09-01

Our objectives included calculating the permeability coefficient and dermal penetration rates (flux value) for 112 chemicals with occupational exposure limits (OELs) according to the LFER (linear free-energy relationship) model developed using published methods. We also attempted to assign skin notations based on each chemical's molecular structure. There are many studies available where formulae for coefficients of permeability from saturated aqueous solutions (K(p)) have been related to physicochemical characteristics of chemicals. The LFER model is based on the solvation equation, which contains five main descriptors predicted from chemical structure: solute excess molar refractivity, dipolarity/polarisability, summation hydrogen bond acidity and basicity, and the McGowan characteristic volume. Descriptor values, available for about 5000 compounds in the Pharma Algorithms Database were used to calculate permeability coefficients. Dermal penetration rate was estimated as a ratio of permeability coefficient and concentration of chemical in saturated aqueous solution. Finally, estimated dermal penetration rates were used to assign the skin notation to chemicals. Defined critical fluxes defined from the literature were recommended as reference values for skin notation. The application of Abraham descriptors predicted from chemical structure and LFER analysis in calculation of permeability coefficients and flux values for chemicals with OELs was successful. Comparison of calculated K(p) values with data obtained earlier from other models showed that LFER predictions were comparable to those obtained by some previously published models, but the differences were much more significant for others. It seems reasonable to conclude that skin should not be characterised as a simple lipophilic barrier alone. Both lipophilic and polar pathways of permeation exist across the stratum corneum. It is feasible to predict skin notation on the basis of the LFER and other published models; from among 112 chemicals 94 (84%) should have the skin notation in the OEL list based on the LFER calculations. The skin notation had been estimated by other published models for almost 94% of the chemicals. Twenty-nine (25.8%) chemicals were identified to have significant absorption and 65 (58%) the potential for dermal toxicity. We found major differences between alternative published analytical models and their ability to determine whether particular chemicals were potentially dermotoxic. Copyright © 2010 Elsevier B.V. All rights reserved.

Cyclic activity at silicic volcanoes: A response to dynamic permeability variations

NASA Astrophysics Data System (ADS)

Lamur, Anthony; Lavallée, Yan; Kendrick, Jackie; Eggertsson, Gudjon; Ashworth, James; Wall, Richard

2017-04-01

Silicic volcanoes exhibit cyclic eruptive activity characterised by effusive (dome growth) to quiescent periods punctuated by short explosive episodes. The latter, characterised by fast emissions of gas and ash into the atmosphere, results from stress release through fracturing and causes significant hazards to the surrounding environment. Understanding the formation, development and closure of fractures as well as their impact on the volcanic system is hence vital for better constraining current models. Here, we present the results of two sets of experiments designed to understand first, the development of permeability through fracturing and second, the timescale over which these fractures can persist in magmas. To characterise the influence of a macro-fracture, the permeability of intact volcanic rocks with a wide porosity range (1-41%) was measured at varying effective pressures (-0.001-30 MPa). We then fractured each sample using the Brazilian disc method to induce a tensile macro-fracture, before measuring the permeability under the same conditions. While our results for intact samples are consistent with previous studies, the results for fractured samples display a distinct permeability-porosity relationship. We show that low porosity samples (<18%) suffer a net increase in permeability of up to 4 orders of magnitude upon fracturing, compared to high porosity samples (>18%) that show a less than 1 order of magnitude increase. This suggests that a macro-fracture has the ability to efficiently localise the flow in low porosity rocks by becoming the prevailing structure in a previously micro-fracture-dominated porous network, whereas at higher porosities fluid flow remains controlled by pore connectivity, irrespective of the presence of a fracture. To assess the longevity of fractures in magmas we developed a novel experimental set-up, in which two glass rods were placed in contact for different timescales at high temperatures before being pulled apart to test the tensile strength recovery of the fracture. We show that fracture healing starts within timescales 50-100 times longer than the structural relaxation time of the melt and that that full healing can be achieved within only a few hours of contact (timescale decreasing with decreasing viscosities) at magmatic temperatures. These results are important for understanding the permeability decrease associated with annealing. We postulate that rapid permeability evolution due to fracturing or fracture healing may be the cause of observed cyclicity at silicic volcanoes, whereby "instantaneous" increases in permeability occur through the development of macro-fractures drives explosions. We propose that the timescale for this cyclicity is governed by the competition between stress build up through gas accumulation under a relatively impervious plug until failure and fracture healing through annealing or, as shown in other studies, mineral precipitation and sintering of particulate material in fractures.

Numerical Analysis of Ground-Water Flow and Salinity in the Ewa Area, Oahu, Hawaii

USGS Publications Warehouse

Oki, Delwyn S.; Souza, William R.; Bolke, Edward I.; Bauer, Glenn R.

1996-01-01

The coastal plain in the Ewa area of southwestern Oahu, Hawaii, is part of a larger, nearly continuous sedimentary coastal plain along Oahu's southern coast. The coastal sediments are collectively known as caprock because they impede the free discharge of ground water from the underlying volcanic aquifers. The caprock is a layered sedimentary system consisting of interbedded marine and terrestrial sediments of both high and low permeability. Before sugarcane cultivation ended in late 1994, shallow ground water from the upper limestone unit, which is about 60 to 200 feet thick, was used primarily for irrigation of sugarcane. A cross-sectional ground-water flow and transport model was used to evaluate the hydrogeologic controls on the regional flow system in the Ewa area. Controls considered were: (1) overall caprock hydraulic conductivity, (2) stratigraphic variations of hydraulic conductivity in the caprock, and (3) recharge. In addition, the effects of a marina excavation were evaluated. Within the caprock, variations in hydraulic conductivity, caused by caprock stratigraphy or discontinuities of the stratigraphic units, are a major control on the direction of ground-water flow and the distribution of water levels and salinity. Model results also show that a reduction of recharge will result in increased salinity throughout the caprock with the greatest change in the upper limestone layer. In addition, the model indicates that excavation of an ocean marina will lower water levels in the upper limestone layer. Results of cross-sectional modeling confirm the general ground-water flow pattern that would be expected in the layered sedimentary system in the Ewa caprock. Ground-water flow is: (1) predominantly upward in the low-permeability sedimentary units, and (2) predominantly horizontal in the high-permeability sedimentary units.

Modeling of time-lapse multi-scale seismic monitoring of CO2 injected into a fault zone to enhance the characterization of permeability in enhanced geothermal systems

NASA Astrophysics Data System (ADS)

Zhang, R.; Borgia, A.; Daley, T. M.; Oldenburg, C. M.; Jung, Y.; Lee, K. J.; Doughty, C.; Altundas, B.; Chugunov, N.; Ramakrishnan, T. S.

2017-12-01

Subsurface permeable faults and fracture networks play a critical role for enhanced geothermal systems (EGS) by providing conduits for fluid flow. Characterization of the permeable flow paths before and after stimulation is necessary to evaluate and optimize energy extraction. To provide insight into the feasibility of using CO2 as a contrast agent to enhance fault characterization by seismic methods, we model seismic monitoring of supercritical CO2 (scCO2) injected into a fault. During the CO2 injection, the original brine is replaced by scCO2, which leads to variations in geophysical properties of the formation. To explore the technical feasibility of the approach, we present modeling results for different time-lapse seismic methods including surface seismic, vertical seismic profiling (VSP), and a cross-well survey. We simulate the injection and production of CO2 into a normal fault in a system based on the Brady's geothermal field and model pressure and saturation variations in the fault zone using TOUGH2-ECO2N. The simulation results provide changing fluid properties during the injection, such as saturation and salinity changes, which allow us to estimate corresponding changes in seismic properties of the fault and the formation. We model the response of the system to active seismic monitoring in time-lapse mode using an anisotropic finite difference method with modifications for fracture compliance. Results to date show that even narrow fault and fracture zones filled with CO2 can be better detected using the VSP and cross-well survey geometry, while it would be difficult to image the CO2 plume by using surface seismic methods.

Geostatistical analysis of regional hydraulic conductivity variations in the Snake River Plain aquifer, eastern Idaho

USGS Publications Warehouse

Welhan, J.A.; Reed, M.F.

1997-01-01

The regional spatial correlation structure of bulk horizontal hydraulic conductivity (Kb) estimated from published transmissivity data from 79 open boreholes in the fractured basalt aquifer of the eastern Snake River Plain was analyzed with geostatistical methods. The two-dimensional spatial correlation structure of In Kb shows a pronounced 4:1 range anisotropy, with a maximum correlation range in the north-northwest- south-southeast direction of about 6 km. The maximum variogram range of In Kb is similar to the mean length of flow groups exposed at the surface. The In Kb range anisotropy is similar to the mean width/length ratio of late Quaternary and Holocene basalt lava flows and the orientations of the major volcanic structural features on the eastern Snake River Plain. The similarity between In Kb correlation scales and basalt flow dimensions and between basalt flow orientations and correlation range anisotropy suggests that the spatial distribution of zones of high hydraulic conductivity may be controlled by the lateral dimensions, spatial distribution, and interconnection between highly permeable zones which are known to occur between lava flows within flow groups. If hydraulic conductivity and lithology are eventually shown to be cross correlative in this geologic setting, it may be possible to stochastically simulate hydraulic conductivity distributions, which are conditional on a knowledge of volcanic stratigraphy.

Nitric oxide and superoxide transport in a cross section of the rat outer medulla. II. Reciprocal interactions and tubulovascular cross talk.

PubMed

Edwards, Aurélie; Layton, Anita T

2010-09-01

In a companion study (Edwards A and Layton AT. Am J Physiol Renal Physiol. doi:10.1152/ajprenal.00680.2009), we developed a mathematical model of nitric oxide (NO), superoxide (O(2)(-)), and total peroxynitrite (ONOO) transport in mid-outer stripe and mid-inner stripe cross sections of the rat outer medulla (OM). We examined how the three-dimensional architecture of the rat OM, together with low medullary oxygen tension (Po(2)), affects the distribution of NO, O(2)(-), and ONOO in the rat OM. In the current study, we sought to determine generation rate and permeability values that are compatible with measurements of medullary NO concentrations and to assess the importance of tubulovascular cross talk and NO-O(2)(-) interactions under physiological conditions. Our results suggest that the main determinants of NO concentrations in the rat OM are the rate of vascular and tubular NO synthesis under hypoxic conditions, and the red blood cell (RBC) permeability to NO (P(NO)(RBC)). The lower the P(NO)(RBC), the lower the amount of NO that is scavenged by hemoglobin species, and the higher the extra-erythrocyte NO concentrations. In addition, our results indicate that basal endothelial NO production acts to significantly limit NaCl reabsorption across medullary thick ascending limbs and to sustain medullary perfusion, whereas basal epithelial NO production has a smaller impact on NaCl transport and a negligible effect on vascular tone. Our model also predicts that O(2)(-) consumption by NO significantly reduces medullary O(2)(-) concentrations, but that O(2)(-) , when present at subnanomolar concentrations, has a small impact on medullary NO bioavailability.

Quantitative structure-retention relationships of flavonoids unraveled by immobilized artificial membrane chromatography.

PubMed

Santoro, Adriana Leandra; Carrilho, Emanuel; Lanças, Fernando Mauro; Montanari, Carlos Alberto

2016-06-10

The pharmacokinetic properties of flavonoids with differing degrees of lipophilicity were investigated using immobilized artificial membranes (IAMs) as the stationary phase in high performance liquid chromatography (HPLC). For each flavonoid compound, we investigated whether the type of column used affected the correlation between the retention factors and the calculated octanol/water partition (log Poct). Three-dimensional (3D) molecular descriptors were calculated from the molecular structure of each compound using i) VolSurf software, ii) the GRID method (computational procedure for determining energetically favorable binding sites in molecules of known structure using a probe for calculating the 3D molecular interaction fields, between the probe and the molecule), and iii) the relationship between partition and molecular structure, analyzed in terms of physicochemical descriptors. The VolSurf built-in Caco-2 model was used to estimate compound permeability. The extent to which the datasets obtained from different columns differ both from each other and from both the calculated log Poct and the predicted permeability in Caco-2 cells was examined by principal component analysis (PCA). The immobilized membrane partition coefficients (kIAM) were analyzed using molecular descriptors in partial least square regression (PLS) and a quantitative structure-retention relationship was generated for the chromatographic retention in the cholesterol column. The cholesterol column provided the best correlation with the permeability predicted by the Caco-2 cell model and a good fit model with great prediction power was obtained for its retention data (R(2)=0.96 and Q(2)=0.85 with four latent variables). Copyright © 2015 Elsevier B.V. All rights reserved.

Origin of Permeability and Structure of Flows in Fractured Media

NASA Astrophysics Data System (ADS)

De Dreuzy, J.; Darcel, C.; Davy, P.; Erhel, J.; Le Goc, R.; Maillot, J.; Meheust, Y.; Pichot, G.; Poirriez, B.

2013-12-01

After more than three decades of research, flows in fractured media have been shown to result from multi-scale geological structures. Flows result non-exclusively from the damage zone of the large faults, from the percolation within denser networks of smaller fractures, from the aperture heterogeneity within the fracture planes and from some remaining permeability within the matrix. While the effect of each of these causes has been studied independently, global assessments of the main determinisms is still needed. We propose a general approach to determine the geological structures responsible for flows, their permeability and their organization based on field data and numerical modeling [de Dreuzy et al., 2012b]. Multi-scale synthetic networks are reconstructed from field data and simplified mechanical modeling [Davy et al., 2010]. High-performance numerical methods are developed to comply with the specificities of the geometry and physical properties of the fractured media [Pichot et al., 2010; Pichot et al., 2012]. And, based on a large Monte-Carlo sampling, we determine the key determinisms of fractured permeability and flows (Figure). We illustrate our approach on the respective influence of fracture apertures and fracture correlation patterns at large scale. We show the potential role of fracture intersections, so far overlooked between the fracture and the network scales. We also demonstrate how fracture correlations reduce the bulk fracture permeability. Using this analysis, we highlight the need for more specific in-situ characterization of fracture flow structures. Fracture modeling and characterization are necessary to meet the new requirements of a growing number of applications where fractures appear both as potential advantages to enhance permeability and drawbacks for safety, e.g. in energy storage, stimulated geothermal energy and non-conventional gas productions. References Davy, P., et al. (2010), A likely universal model of fracture scaling and its consequence for crustal hydromechanics, Journal of Geophysical Research-Solid Earth, 115, 13. de Dreuzy, J.-R., et al. (2012a), Influence of fracture scale heterogeneity on the flow properties of three-dimensional Discrete Fracture Networks (DFN), J. Geophys. Res.-Earth Surf., 117(B11207), 21 PP. de Dreuzy, J.-R., et al. (2012b), Synthetic benchmark for modeling flow in 3D fractured media, Computers and Geosciences(0). Pichot, G., et al. (2010), A Mixed Hybrid Mortar Method for solving flow in Discrete Fracture Networks, Applicable Analysis, 89(10), 1729-1643. Pichot, G., et al. (2012), Flow simulation in 3D multi-scale fractured networks using non-matching meshes, SIAM Journal on Scientific Computing (SISC), 34(1). Figure: (a) Fracture network with a broad-range of fracture lengths. (b) Flows (log-scale) with homogeneous fractures. (c) Flows (log-scale) with heterogeneous fractures [de Dreuzy et al., 2012a]. The impact of the fracture apertures (c) is illustrated on the organization of flows.

Temperature and composition of carbonate cements record early structural control on cementation in a nascent deformation band fault zone: Moab Fault, Utah, USA

NASA Astrophysics Data System (ADS)

Hodson, Keith R.; Crider, Juliet G.; Huntington, Katharine W.

2016-10-01

Fluid-driven cementation and diagenesis within fault zones can influence host rock permeability and rheology, affecting subsequent fluid migration and rock strength. However, there are few constraints on the feedbacks between diagenetic conditions and structural deformation. We investigate the cementation history of a fault-intersection zone on the Moab Fault, a well-studied fault system within the exhumed reservoir rocks of the Paradox Basin, Utah, USA. The fault zone hosts brittle structures recording different stages of deformation, including joints and two types of deformation bands. Using stable isotopes of carbon and oxygen, clumped isotope thermometry, and cathodoluminescence, we identify distinct source fluid compositions for the carbonate cements within the fault damage zone. Each source fluid is associated with different carbonate precipitation temperatures, luminescence characteristics, and styles of structural deformation. Luminescent carbonates appear to be derived from meteoric waters mixing with an organic-rich or magmatic carbon source. These cements have warm precipitation temperatures and are closely associated with jointing, capitalizing on increases in permeability associated with fracturing during faulting and subsequent exhumation. Earlier-formed non-luminescent carbonates have source fluid compositions similar to marine waters, low precipitation temperatures, and are closely associated with deformation bands. The deformation bands formed at shallow depths very early in the burial history, preconditioning the rock for fracturing and associated increases in permeability. Carbonate clumped isotope temperatures allow us to associate structural and diagenetic features with burial history, revealing that structural controls on fluid distribution are established early in the evolution of the host rock and fault zone, before the onset of major displacement.

Structural fabrics, mineralization and Lamaride kinematics of the Idaho Springs-Ralston shear zone, Colorado mineral belt and central Front Range uplift

USGS Publications Warehouse

Caine, Jonathan S.; Nelson, E.P.; Beach, S.T.; Layer, P.W.

2006-01-01

The Idaho Springs and Central City mining districts form the central portion of a structurally controlled hydrothermal precious- and base-metal vein system in the Front Range of the northeast-trending Colorado Mineral Belt. Three new 40Ar/39Ar plateau ages on hydrothermal sericite indicate the veins formed during the Laramide orogeny between 65.4??1.5 - 61.9??1.3 Ma. We compile structural geologic data from surface geological maps, subsurface mine maps, and theses for analysis using modern graphical methods and integration into models of formation of economic mineral deposits. Structural data sets, produced in the 1950s and 1960s by the U.S. Geological Survey, are compiled for fabric elements, including metamorphic foliations, fold axial trends, major brittle fault zones, quartz and precious- and base-metal veins and fault veins, Tertiary dikes, and joints. These fabric elements are plotted on equal-area projections and analyzed for mean fabric orientations. Strike-slip fault-vein sets are mostly parallel or sub-parallel, and not conjugate as interpreted by previous work; late-stage, normal-slip fault veins possibly show a pattern indicative of triaxial strain. Fault-slip kinematic analysis was used to model the trend of the Laramide maximum horizontal stress axis, or compression direction, and to determine compatibility of opening and shear motions within a single stress field. The combined-model maximum compression direction for all strike slip fault veins is ???068??, which is consistent with published Laramide compression directions of ???064?? (mean of 23 regional models) and ???072?? for the Front Range uplift. The orientations of fabric elements were analyzed for mechanical and kinematic compatibility with opening, and thus permeability enhancement, in the modeled regional east-northeast, Laramide compression direction. The fabric orientation analysis and paleostress modeling show that structural permeability during mineralization was enhanced along pre-existing metamorphic foliations and fold axial planes. Large orientation dispersion in most fabric elements likely caused myriad potential pathways for permeability. The dominant orientations of opening and shear mode structures are consistent with a sub-parallel network of structures that formed in the Laramide east-northeast compression direction. The results presented demonstrate the importance of using mechanical and kinematic theory integrated with contemporary ideas of permeability structure to better understand the coupled nature of fluid flow, mineral deposition, stress, and strain. Further, the results demonstrate that there is significant internal strain within this basement-cored uplift that was localized by optimally oriented pre-existing structures in a regional stress field.

Structural architecture and petrophysical properties of the Rocca di Neto extensional fault zone developed in the shallow marine sediments of the Crotone Basin (Southern Apennines, Italy).

NASA Astrophysics Data System (ADS)

Pizzati, Mattia; Balsamo, Fabrizio; Iacumin, Paola; Swennen, Rudy; Storti, Fabrizio

2017-04-01

In this contribution we describe the architecture and petrophysical properties of the Rocca di Neto extensional fault zone in loose and poorly lithified sediments, located in the Crotone forearc basin (south Italy). To this end, we combined fieldwork with microstructural observations, grain size analysis, and in situ permeability measurements. The studied fault zone has an estimated maximum displacement of 80-90 m and separates early Pleistocene age (Gelasian) sands in the footwall from middle Pleistocene (Calabrian) silty clay in the hangingwall. The analysed outcrop consists of about 70 m section through the fault zone mostly developed in the footwall block. Fault zone consists of four different structural domains characterized by distinctive features: (1) <1 m-thick fault core (where the majority of the displacement is accommodated) in which bedding is transposed into foliation imparted by grain preferential orientation and some black gouges decorate the main slip surfaces; (2) zone of tectonic mixing characterized by a set of closely spaced and anastomosed deformation bands parallel to the main slip surface; (3) about 8 m-thick footwall damage zone characterized by synthetic and antithetic sets of deformation bands; (4) zone of background deformation with a few, widely-spaced conjugate minor faults and deformation bands. The boundary between the relatively undeformed sediments and the damage zone is not sharp and it is characterized by a progressive decrease in deformation intensity. The silty clay in the hangingwall damage zone is characterized by minor faults. Grain size and microstructural data indicate that particulate flow with little amount of cataclasis is the dominant deformation mechanism in both fault core rocks and deformation bands. Permeability of undeformed sediments is about 70000 mD, whereas the permeability in deformation bands ranges from 1000 to 18000 mD; within the fault core rocks permeability is reduced up to 3-4 orders of magnitude respect to the undeformed domains. Structural and petrophysical data suggest that the Rocca di Neto fault zone may compartmentalize the footwall block due to both juxtaposition of clay-rich lithology in the hangingwall and the development of low permeability fault core rocks.

An Integrated Tensorial Approach for Quantifying Porous, Fractured Rocks

NASA Astrophysics Data System (ADS)

Healy, David; Rizzo, Roberto; Harland, Sophie; Farrell, Natalie; Browning, John; Meredith, Phil; Mitchell, Tom; Bubeck, Alodie; Walker, Richard

2017-04-01

The patterns of fractures in deformed rocks are rarely uniform or random. Fracture orientations, sizes, shapes and spatial distributions often exhibit some kind of order. In detail, there may be relationships among the different fracture attributes e.g. small fractures dominated by one orientation, and larger fractures by another. These relationships are important because the mechanical (e.g. strength, anisotropy) and transport (e.g. fluids, heat) properties of rock depend on these fracture patterns and fracture attributes. Based on previously published work (Oda, Cowin, Sayers & Kachanov) this presentation describes an integrated tensorial approach to quantifying fracture networks and predicting the key properties of fractured rock: permeability and elasticity (and in turn, seismic velocities). Each of these properties can be represented as tensors, and these entities capture the essential 'directionality', or anisotropy of the property. In structural geology, we are familiar with using tensors for stress and strain, where these concepts incorporate volume averaging of many forces (in the case of the stress tensor), or many displacements (for the strain tensor), to produce more tractable and more computationally efficient quantities. It is conceptually attractive to formulate both the structure (the fracture network) and the structure-dependent properties (permeability, elasticity) in a consistent way with tensors of 2nd and 4th rank, as appropriate. Examples are provided to highlight the interdependence of the property tensors with the geometry of the fracture network. The fabric tensor (or orientation tensor of Scheidegger, Woodcock) describes the orientation distribution of fractures in the network. The crack tensor combines the fabric tensor (orientation distribution) with information about the fracture density and fracture size distribution. Changes to the fracture network, manifested in the values of the fabric and crack tensors, translate into changes in predicted permeability and elasticity (seismic velocity). Conversely, this implies that measured changes in any of the in situ properties or responses in the subsurface (e.g. permeability, seismic velocity) could be used to predict, or at least constrain, the fracture network. Explicitly linking the fracture network geometry to the permeability and elasticity (seismic velocity) through a tensorial formulation provides an exciting and efficient alternative to existing approaches.

Investigation of Kevlar fabric based materials for use with inflatable structures

NASA Technical Reports Server (NTRS)

Niccum, R. J.; Munson, J. B.

1974-01-01

Design, manufacture and testing of laminated and coated composite materials incorporating a structural matrix of Kevlar are reported in detail. The practicality of using Kevlar in aerostat materials is demonstrated and data are provided on practical weaves, lamination and coating particulars, rigidity, strength, weight, elastic coefficients, abrasion resistance, crease effects, peel strength, blocking tendencies, helium permeability, and fabrication techniques. Properties of the Kevlar based materials are compared with conventional, Dacron reinforced counterparts. A comprehensive test and qualification program is discussed and quantitative biaxial tensile and shear test data are provided. The investigation shows that single ply laminates of Kevlar and plastic films offer significant strength to weight improvements, are less permeable than two ply coated materials, but have a lower flex life.

[Use of porous permeable titanium nickelide implants in surgery of the frontal and maxillary sinuses (a clinical-experimental study)].

PubMed

Starokha, A V; Itin, V I; Kovrizhnykh, V V; Ryzhov, A I; Monasevich, L A

1990-01-01

The purpose of the investigation was to study the efficacy of closing the bone defect in facial walls of the frontal and maxillary sinuses, formed as a result of their purulent inflammation, by porous permeable titanium nickelide. Analysis of the experimental data (18 dogs) and clinical observations (20 patients in whom the anatomic structure and function of frontal and maxillary sinuses with osteomyelitis were restored by an antibiotic pooling implantation material) gives evidence that the material can be well used to reconstruct an organ with an infected wound. The porous structure of the bioinert graft facilitates the ingrowth of osteogenic tissues, which becomes packed in the bone matrix without any intermediate connective tissue layer.

Interconnected Porous Polymers with Tunable Pore Throat Size Prepared via Pickering High Internal Phase Emulsions.

PubMed

Xu, Hongyun; Zheng, Xianhua; Huang, Yifei; Wang, Haitao; Du, Qiangguo

2016-01-12

Interconnected macroporous polymers were prepared by copolymerizing methyl acrylate (MA) via Pickering high internal phase emulsion (HIPE) templates with modified silica particles. The pore structure of the obtained polymer foams was observed by field-emission scanning electron microscopy (FE-SEM). Gas permeability was characterized to evaluate the interconnectivity of macroporous polymers. The polymerization shrinkage of continuous phase tends to form open pores while the solid particles surrounding the droplets act as barriers to produce closed pores. These two conflicting factors are crucial in determining the interconnectivity of macroporous polymers. Thus, poly-Pickering HIPEs with high permeability and well-defined pore structure can be achieved by tuning the MA content, the internal phase fraction, and the content of modified silica particles.

Capsules made from prefabricated thin films

NASA Astrophysics Data System (ADS)

Amstad, Esther

2018-02-01

Capsules are composed of a core, typically a liquid containing active substances, and a surrounding shell. They are used to delay the degradation of active ingredients, protect them from reacting or interacting with substances contained in the surrounding shell, or to prevent premature consumption of encapsulants (1, 2). The performance of capsules is often determined by their permeability toward encapsulants and stability against rupture; these parameters can be adjusted with the composition, structure, and thickness of the shell (3, 4). Mechanically robust capsules with a minimal permeability even toward low molecular weight substances often have rather thick shells (5). On page 775 of this issue, Kumar et al. (6) report an elegant process to fabricate capsules with very thin, rigid shells that display a low permeability even toward small encapsulants.

Strong coercivity reduction and high initial permeability in NiCoP coated BaFe12O19-polystyrene bilayer composite

NASA Astrophysics Data System (ADS)

Hamad, Mahmoud A.; El-Sayed, Adly H.; Hemeda, O. M.; Tawfik, A.

2016-03-01

Soft-magnetic NiCoP coated hard-magnetic M-type ferrite BaFe12O19 (BaM)-polystyrene (PS) bilayer composite film was successfully synthesized. X-ray diffraction peaks exhibited no change in the structure of BaM after coating with PS. The NiCoP coated BaM-PS composite exhibited a wasp-waisted magnetic hysteretic loop with remarkable reduction in the coercivity, remanence and squareness with respect to BaM-PS, which is useful for the core of a magnetic switching device to control currents so large that they are unmanageable. Moreover, the initial permeability measurement exhibits initial permeability of around 100 000 and thermal stability up to 558 K, which is good for flux-amplifying components of smaller inductors.

Apparatus for diffusion separation

DOEpatents

Nierenberg, William A.; Pontius, Rex B.

1976-08-10

1. The method of testing the separation efficiency of porous permeable membranes which comprises causing a stream of a gaseous mixture to flow into contact with one face of a finely porous permeable membrane under such conditions that a major fraction of the mixture diffuses through the membrane, maintaining a rectangular cross section of the gaseous stream so flowing past said membrane, continuously recirculating the gas that diffuses through said membrane and continuously withdrawing the gas that does not diffuse through said membrane and maintaining the volume of said recirculating gas constant by continuously introducing into said continuously recirculating gas stream a mass of gas equivalent to that which is continuously withdrawn from said gas stream and comparing the concentrations of the light component in the entering gas, the withdrawn gas and the recirculated gas in order to determine the efficiency of said membrane.

Porous poly(benzimidazole) membrane for all vanadium redox flow battery

NASA Astrophysics Data System (ADS)

Luo, Tao; David, Oana; Gendel, Youri; Wessling, Matthias

2016-04-01

Porous poly(benzimidazole) (PBI) membranes of low vanadium ions permeability are described for an all vanadium redox flow battery (VRFB). The PBI membrane was prepared by a water vapour induced phase inversion process of a PBI polymer solution. The membrane has a symmetrical cross-sectional morphology. A low water permeability of 16.5 L (m2 h bar)-1 indicates the high hydraulic resistance stemming from a closed cell morphology with nanoporous characteristics. The PBI membrane doped with 2.5 M H2SO4 shows a proton conductivity of 16.6 mS cm-1 and VO2+ permeability as low as 4.5 × 10-8 cm2 min-1. The stability test of dense PBI membrane in VO2+ solution indicates good chemical stability. An all vanadium redox flow battery (VRFB) operated with the porous PBI membrane shows 98% coulombic efficiency and more than 10% higher energy efficiency compared to VRFB operated with Nafion 112 at applied current densities of 20-40 mA cm-2. High in situ stability of the porous PBI membrane was confirmed by about 50 cycles of continuous charge and discharge operation of the battery.

Biomimetic carriers mimicking leukocyte plasma membrane to increase tumor vasculature permeability

NASA Astrophysics Data System (ADS)

Palomba, R.; Parodi, A.; Evangelopoulos, M.; Acciardo, S.; Corbo, C.; De Rosa, E.; Yazdi, I. K.; Scaria, S.; Molinaro, R.; Furman, N. E. Toledano; You, J.; Ferrari, M.; Salvatore, F.; Tasciotti, E.

2016-10-01

Recent advances in the field of nanomedicine have demonstrated that biomimicry can further improve targeting properties of current nanotechnologies while simultaneously enable carriers with a biological identity to better interact with the biological environment. Immune cells for example employ membrane proteins to target inflamed vasculature, locally increase vascular permeability, and extravasate across inflamed endothelium. Inspired by the physiology of immune cells, we recently developed a procedure to transfer leukocyte membranes onto nanoporous silicon particles (NPS), yielding Leukolike Vectors (LLV). LLV are composed of a surface coating containing multiple receptors that are critical in the cross-talk with the endothelium, mediating cellular accumulation in the tumor microenvironment while decreasing vascular barrier function. We previously demonstrated that lymphocyte function-associated antigen (LFA-1) transferred onto LLV was able to trigger the clustering of intercellular adhesion molecule 1 (ICAM-1) on endothelial cells. Herein, we provide a more comprehensive analysis of the working mechanism of LLV in vitro in activating this pathway and in vivo in enhancing vascular permeability. Our results suggest the biological activity of the leukocyte membrane can be retained upon transplant onto NPS and is critical in providing the particles with complex biological functions towards tumor vasculature.

A three-dimensional transient mixed hybrid finite element model for superabsorbent polymers with strain-dependent permeability.

PubMed

Yu, Cong; Malakpoor, Kamyar; Huyghe, Jacques M

2018-05-16

A hydrogel is a cross-linked polymer network with water as solvent. Industrially widely used superabsorbent polymers (SAP) are partially neutralized sodium polyacrylate hydrogels. The extremely large degree of swelling is one of the most distinctive characteristics of such hydrogels, as the volume increase can be about 30 times its original volume when exposed to physiological solution. The large deformation resulting from the swelling demands careful numerical treatment. In this work, we present a biphasic continuum-level swelling model using the mixed hybrid finite element method (MHFEM) in three dimensions. The hydraulic permeability is highly dependent on the swelling ratio, resulting in values that are orders of magnitude apart from each other. The property of the local mass conservation of MHFEM contributes to a more accurate calculation of the deformation as the permeability across the swelling gel in a transient state is highly non-uniform. We show that the proposed model is able to simulate the free swelling of a random-shaped gel and the squeezing of fluid out of a swollen gel. Finally, we make use of the proposed numerical model to study the onset of surface instability in transient swelling.

Assessment of Blood-brain Barrier Permeability by Intravenous Infusion of FITC-labeled Albumin in a Mouse Model of Neurodegenerative Disease.

PubMed

Di Pardo, Alba; Castaldo, Salvatore; Capocci, Luca; Amico, Enrico; Vittorio, Maglione

2017-11-08

Disruption of blood-brain barrier (BBB) integrity is a common feature for different neurological and neurodegenerative diseases. Although the interplay between perturbed BBB homeostasis and the pathogenesis of brain disorders needs further investigation, the development and validation of a reliable procedure to accurately detect BBB alterations may be crucial and represent a useful tool for potentially predicting disease progression and developing targeted therapeutic strategies. Here, we present an easy and efficient procedure for evaluating BBB leakage in a neurodegenerative condition like that occurring in a preclinical mouse model of Huntington disease, in which defects in the permeability of BBB are clearly detectable precociously in the disease. Specifically, the high molecular weight fluorescein isothiocyanate labelled (FITC)-albumin, which is able to cross the BBB only when the latter is impaired, is acutely infused into a mouse jugular vein and its distribution in the vascular or parenchymal districts is then determined by fluorescence microscopy. Accumulation of green fluorescent-albumin in the brain parenchyma functions as an index of aberrant BBB permeability and, when quantitated by using Image J processing software, is reported as Green Fluorescence Intensity.

[Permeability of isolated rat hepatocyte plasma membranes for molecules of dimethyl sulfoxide].

PubMed

Kuleshova, L G; Gordienko, E A; Kovalenko, I F

2014-01-01

We have studied permeability of isolated rat hepatocyte membranes for molecules of dimethyl sulfoxide (DMSO) at different hypertonicity of a cryoprotective medium. The permeability coefficient of hepatocyte membranes κ1 for DMSO molecules was shown to be the differential function of osmotic pressure between a cell and an extracellular medium. Ten-fold augmentation of DMSO concentration in the cryoprotective medium causes the decrease of permeability coefficients κ1 probably associated with the increased viscosity in membrane-adjacent liquid layers as well as partial limitations appeared as a result of change in cell membrane shape after hepatocyte dehydration. We have found out that in aqueous solutions of NaCl (2246 mOsm/l) and DMSO (2250 mOsm/l) the filtration coefficient L(p) in the presence of a penetrating cryoprotectant (L(pDMSO) = (4.45 ± 0.04) x 10(-14) m3/Ns) is 3 orders lower compared to the case with electrolyte (L(pNaCl) = (2.25 ± 0.25) x 10(-11) m3/Ns). This phenomenon is stipulated by the cross impact of flows of a cryoprotectant and water at the stage of cell dehydration. Pronounced lipophilicity of DMSO, geometric parameters of its molecule as well as the presence of large aqueous pores in rat hepatocyte membranes allow of suggesting the availability of two ways of penetrating this cryoprotectant into the cells by non-specific diffusion through membrane lipid areas and hydrophilic channels.

Moisture Management Behaviour of Knitted Fabric from Structurally Modified Ring and Vortex Spun Yarn

NASA Astrophysics Data System (ADS)

Sharma, Navendu; Kumar, Pawan; Bhatia, Dinesh; Sinha, Sujit Kumar

2016-10-01

The acceptability of a new product is decided by its performance, level of improvement in quality and economy of production. The basic aim of generating micro pores in a textile structure is to provide better thermo-physiological comfort by enhancing the breathability and hence improving moisture management behaviour. In the present study, an attempt has been made to create a relatively more open structure through removal of a component. A comparative assessment with a homogeneous and parent yarn was also made. Yarns of two linear densities, each from ring and vortex spinning systems were produced using 100 % polyester and 80:20 polyester/cotton blend. The modified yarn was produced by removing a component, viz; cotton, by treatment with sulphuric acid from the blended yarn. The knitted fabric from modified yarn was found to show significant improvement in air permeability, water vapour permeability and total absorbency while the wicking characteristic was found to decline.

Effects of electromagnetic pulse irradiation on the mouse blood-testicle barrier.

PubMed

Hou, Wu-Gang; Zhao, Jie; Li, Zhen; Li, Wei; Li, Teng; Xiong, Li-Ze; Zhang, Yuan-Qiang

2012-07-01

To investigate the effects of electromagnetic pulse irradiation on the mouse blood-testicle barrier (BTB) and spermatogenesis. After whole body irradiation with 400 kV/m electromagnetic pulse irradiation, the mouse testicles and BTB permeability were observed using hematoxylin-eosin, Evans blue, and lanthanum nitrate as tracers. The expression of the BTB tight junction protein occludin was examined using real-time polymerase chain reaction and Western blotting. At 1, 7, and 14 days after irradiation, the BTB structure was damaged, the BTB permeability was significantly increased, numerous apoptotic or necrotic spermatogenic cells were found in the lumen, and the mRNA and protein expression levels of occludin were markedly decreased. The BTB structure and occludin expression levels had gradually recovered by 21 and 28 days after irradiation. Electromagnetic pulse irradiation damaged the structure and function of mouse BTB, resulting in apoptosis or necrosis of the spermatogenic cells. Copyright © 2012 Elsevier Inc. All rights reserved.

Submarine slope failures due to pipe structure formation.

PubMed

Elger, Judith; Berndt, Christian; Rüpke, Lars; Krastel, Sebastian; Gross, Felix; Geissler, Wolfram H

2018-02-19

There is a strong spatial correlation between submarine slope failures and the occurrence of gas hydrates. This has been attributed to the dynamic nature of gas hydrate systems and the potential reduction of slope stability due to bottom water warming or sea level drop. However, 30 years of research into this process found no solid supporting evidence. Here we present new reflection seismic data from the Arctic Ocean and numerical modelling results supporting a different link between hydrates and slope stability. Hydrates reduce sediment permeability and cause build-up of overpressure at the base of the gas hydrate stability zone. Resulting hydro-fracturing forms pipe structures as pathways for overpressured fluids to migrate upward. Where these pipe structures reach shallow permeable beds, this overpressure transfers laterally and destabilises the slope. This process reconciles the spatial correlation of submarine landslides and gas hydrate, and it is independent of environmental change and water depth.

Influence of the Testa on Seed Dormancy, Germination, and Longevity in Arabidopsis1

PubMed Central

Debeaujon, Isabelle; Léon-Kloosterziel, Karen M.; Koornneef, Maarten

2000-01-01

The testa of higher plant seeds protects the embryo against adverse environmental conditions. Its role is assumed mainly by controlling germination through dormancy imposition and by limiting the detrimental activity of physical and biological agents during seed storage. To analyze the function of the testa in the model plant Arabidopsis, we compared mutants affected in testa pigmentation and/or structure for dormancy, germination, and storability. The seeds of most mutants exhibited reduced dormancy. Moreover, unlike wild-type testas, mutant testas were permeable to tetrazolium salts. These altered dormancy and tetrazolium uptake properties were related to defects in the pigmentation of the endothelium and its neighboring crushed parenchymatic layers, as determined by vanillin staining and microscopic observations. Structural aberrations such as missing layers or a modified epidermal layer in specific mutants also affected dormancy levels and permeability to tetrazolium. Both structural and pigmentation mutants deteriorated faster than the wild types during natural aging at room temperature, with structural mutants being the most strongly affected. PMID:10677433

An audio-magnetotelluric investigation in Terceira Island (Azores)

NASA Astrophysics Data System (ADS)

Monteiro Santos, Fernando A.; Trota, António; Soares, António; Luzio, Rafael; Lourenço, Nuno; Matos, Liliana; Almeida, Eugénio; Gaspar, João L.; Miranda, Jorge M.

2006-08-01

Ten audio-magnetotelluric soundings have been carried out along a profile crossing the Serra do Cume caldera in the eastern part of the Terceira Island (Azores). The main objectives of this investigation were to detect geoelectrical features related with tectonic structures and to characterize regional hydrological and hydrothermal aspects mainly those related to geothermal fluid dynamics. Three-dimensional numerical investigation showed that the data acquired at periods shorter than 1 s are not significantly affected by ocean effect. The data was analysed using the Smith's decomposition method in order to investigate possible distortions caused by superficial structures and to estimate a global regional strike. The results suggest that in general the soundings were not distorted. A regional N55°W strike was chosen for the two-dimensional data inversion. The low-resistivity zones (10-30 ohm-m) displayed in the central part of the 2-D geoelectrical model have been interpreted as caused by hydrothermal circulation. The low-resistivity anomalies at the ends of the profile might be attributed to alteration zones with interaction of seawater intrusion. High-resistivity (> 300 ohm-m) values have been related with less permeable zones in the SW of Cinco Picos and Guilherme Moniz caldera walls.

Development and characterization of carrageenan/grapefruit seed extract composite films for active packaging.

PubMed

Kanmani, Paulraj; Rhim, Jong-Whan

2014-07-01

Carrageenan-based antimicrobial films were developed by incorporation of grape fruit seed extract (GSE) at different concentration into the polymer using a solvent casing method and their physical, mechanical, and antimicrobial properties were examined. The carrageenan/GSE composite films appeared yellowish tint due to the polyphenolic compounds in the GSE. SEM analysis showed rough surface with sponge like structures on the cross section of the films. FT-IR results indicated at GSE had good compatibility with carrageenan. The amorphous structure of polymer films was not changed by the incorporation of GSE. But, the addition of GSE increased moisture content, water vapor permeability, and surface hydrophilicity of the films. The tensile strength and elastic modulus decreased with increasing content of GSE, however, the elongation at break increased significantly up to 6.6μg/mL of GSE then decreased thereafter. Thermal stability of the films was not influenced by GSE incorporation. The carrageenan/GSE composite films exhibited great antibacterial activity against food borne pathogens. These results suggest that the carrageenan-based composite films have a high potential for being used as an antimicrobial or active food packaging applications. Copyright © 2014 Elsevier B.V. All rights reserved.

Preparation of quaternary amine monolithic column for strong anion-exchange chromatography and its application to the separation of Enterovirus 71.

PubMed

Gu, Huimin; Yin, Dezhong; Ren, Jie; Zhang, Baoliang; Zhang, Qiuyu

2016-10-15

Large size virion is unable to diffuse into pores of conventional porous chromatography particles. Therefore, separation of virion by conventional column-packing materials is not quite efficient. To solve this problem, a monolithic column with large convective pores and quaternary amine groups was prepared and was applied to separate Enterovirus 71 (EV71, ≈5700-6000kDa). Cross-section, pore structure, hydrodynamic performance, adsorption property and dynamic binding capacity of prepared monolithic column were determined. Double-pore structures, macropore at 2472nm and mesopore at 5-60nm, were formed. The porosity was up to 63.3%, which enable higher permeability and lower back pressure of the monolithic column than commercial UNO™ Q1 column. Based on the breakthrough curves, the loading capacity of bovine serum albumin was calculated to be 42.0mg per column. In addition, prepared quaternary amine monolithic column was proved to be suitable for the separation of protein mixture by strong anion-exchange chromatography. As a practical application, prepared monolith column presents excellent performance to the separation of EV71 from virus-proteins mixture. Copyright © 2016 Elsevier B.V. All rights reserved.

Perfluorohexadecanoic acid increases paracellular permeability in endothelial cells through the activation of plasma kallikrein-kinin system.

PubMed

Liu, Qian S; Hao, Fang; Sun, Zhendong; Long, Yanmin; Zhou, Qunfang; Jiang, Guibin

2018-01-01

Per- and polyfluoroalkyl substances (PFASs) are ubiquitous and high persistent in human blood, thus potentially inducing a myriad of deleterious consequences. Plasma kallikrein-kinin system (KKS), which physiologically regulates vascular permeability, is vulnerable to exogenous stimulators, like PFASs with long-chain alkyl backbone substituted by electronegative fluorine. The study on the interactions of PFASs with the KKS and the subsequent effects on vascular permeability would be helpful to illustrate how the chemicals penetrate the biological vascular barriers to reach different tissues. In present study, three representative PFASs, including perfluorooctane sulfonic acid (PFOS), perfluorooctanoic acid (PFOA) and perfluorohexadecanoic acid (PFHxDA), were investigated for their effects on the activation of the KKS, paracellular permeability in human retina endothelial cells (HRECs) and integrity of the adherens junctions. In contrast to either PFOS or PFOA, PFHxDA efficiently triggered KKS activation in a concentration-dependent manner based on protease activity assays. The plasma activated by PFHxDA significantly increased paracellular permeability of HRECs through the degradation of adherens junctions. As evidenced by the antagonistic effect of aprotinin, PFHxDA-involved effects on vascular permeability were mediated by KKS activation. The results herein firstly revealed the mechanistic pathway for PFHxDA induced effects on vascular endothelial cells. Regarding the possible structure-related activities of the chemicals, this finding would be of great help in the risk assessment of PFASs. Copyright © 2017 Elsevier Ltd. All rights reserved.

Transport characteristics of urea transporter-B.

PubMed

Yang, Baoxue

2014-01-01

UT-B represents the major urea transporter in erythrocytes, in addition to being expressed in kidney descending vasa recta, brain, spleen, ureter, bladder, and testis. Expression of urea transporter UT-B confers high urea permeability to mammalian erythrocytes. Erythrocyte membranes are also permeable to various urea analogues, suggesting common transport pathways for urea and structurally similar solutes. UT-B is highly permeable to urea and the chemical analogues formamide, acetamide, methylurea, methylformamide, ammonium carbamate, and acrylamide, each with a Ps > 5.0 × 10(-6) cm/s at 10 °C. The amides formamide, acetamide, acrylamide, and butyramide efficiently diffuse across lipid bilayers. The urea analogues dimethylurea, acryalmide, methylurea, thiourea, and methylformamide inhibit UT-B-mediated urea transport by >60 % by a pore-blocking mechanism. UT-B is also a water channel in erythrocytes and has a single-channel water permeability that is similar to aquaporin-1. Whether UT-B is an NH3 channel still needs further study. Urea permeability (Purea) in erythrocytes differs between different mammals. Carnivores (dog, fox, cat) exhibit high Purea. In contrast, herbivores (cow, donkey, sheep) show much lower Purea. Erythrocyte Purea in human and pig (omnivores) was intermediate. Rodents and lagomorphs (mouse, rat, rabbit) have Purea intermediate between carnivores and omnivores. Birds that do not excrete urea and do not express UT-B in their erythrocytes have very low values. In contrast to Purea, water permeability is relatively similar in all mammals studied. This chapter will provide information about the transporter characteristics of UT-B.