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  1. Crustal Permeability

    NASA Astrophysics Data System (ADS)

    Ingebritsen, S.; Gleeson, T.

    2014-12-01

    Existing data and models support a distinction between the hydrodynamics of the brittle upper crust, where topography, permeability contrasts, and magmatic heat sources dominate patterns of flow and externally derived (meteoric) fluids are common, and the ductile lower crust, dominated by devolatilization reactions and internally derived fluids. The permeability structure of the uppermost (~<1 km) crust is highly heterogeneous, and controls include primary lithology, porosity, rheology, geochemistry, and tectonic and time-temperature histories of the rocks. Systematic permeability differences among original lithologies persist to contact-metamorphic depths of 3-10 km, but are not evident at regional-metamorphic depths of 10-30+ km - presumably because, at such depths, metamorphic textures become largely independent of the original lithology. Permeability can vary in time as well as space, and its temporal evolution may be gradual or abrupt: streamflow responses to moderate to large earthquakes demonstrate that dynamic stresses can instantaneously change permeability by factors of up to 20 on a regional scale, whereas a 10-fold decrease in the permeability of a package of shale in a compacting basin may require 107years. Temporal variation is enhanced by strong chemical and thermal disequilibrium; thus lab experiments involving hydrothermal flow in crystalline rocks under pressure, temperature, and chemistry gradients often result in 10-fold permeability decreases over daily to sub-annual time scales. Recent research on enhanced geothermal reservoirs, ore-forming systems, and the hydrologic effects of earthquakes consistently shows that shear dislocation caused by tectonic forcing or fluid injection can increase near-to intermediate-field permeability by factors of 100 to 1000. Nonetheless, considering permeability as static parameter is often a reasonable assumption for low-temperature hydrogeologic investigations with time scales of days to decades.

  2. Permeability of Clay Concretes

    NASA Astrophysics Data System (ADS)

    Solomon, F.; Ekolu, S. O.

    2015-11-01

    This paper presents an investigation on the effect of clay addition on water permeability and air permeability of concretes. Clay concrete mixes consisted of 0 to 40% clay content incorporated as cement replacement. Flow methods using triaxial cells and air permeameters were used for measuring the injected water and air flows under pressure. It was found that the higher the clay content in the mixture, the greater the permeability. At higher water-cement ratios (w/c), the paste matrix is less dense and easily allows water to ingress into concrete. But at high clay contents of 30 to 40% clay, the variation in permeability was significantly diminished among different concrete mixtures. It was confirmed that air permeability results were higher than the corresponding water permeability values when all permeability coefficients were converted to intrinsic permeability values.

  3. EPA Permeable Surface Research

    EPA Science Inventory

    EPA recognizes permeable surfaces as an effective post-construction infiltration-based Best Management Practice to mitigate the adverse effects of stormwater runoff. The professional user community conceptually embraces permeable surfaces as a tool for making runoff more closely...

  4. Permeability and relative permeability in rocks

    SciTech Connect

    Blair, S.C.; Berryman, J.G.

    1990-10-01

    Important features of the topology of the pore space of rocks can be usefully quantified by analyzing digitized images of rock cross sections. One approach computes statistical correlation functions using modern image processing techniques. These correlation functions contain information about porosity, specific surface area, tortuosity, formation factor, and elastic constants, as well as the fluid permeability and relative permeability. The physical basis of this approach is discussed and examples of the results for various sandstones are presented. The analysis shows that Kozeny-Carman relations and Archie's empirical laws must be modified to account for finite percolation thresholds in order to avoid unphysical behavior in the calculated relative permeabilities. 33 refs., 4 figs., 1 tab.

  5. Permeability of Dentine

    PubMed Central

    Ghazali, Farid Bin Che

    2003-01-01

    This is an update on the present integrated knowledge regarding dentine permeability that assumed a role in dentine sensitivity and contribute clinically to the effective bonding properties of restorative dental materials. This paper will attempt to refer to in vivo and in vitro studies of dentine permeability and the various interrelated factors governing it. PMID:23365497

  6. Seismic waves increase permeability.

    PubMed

    Elkhoury, Jean E; Brodsky, Emily E; Agnew, Duncan C

    2006-06-29

    Earthquakes have been observed to affect hydrological systems in a variety of ways--water well levels can change dramatically, streams can become fuller and spring discharges can increase at the time of earthquakes. Distant earthquakes may even increase the permeability in faults. Most of these hydrological observations can be explained by some form of permeability increase. Here we use the response of water well levels to solid Earth tides to measure permeability over a 20-year period. At the time of each of seven earthquakes in Southern California, we observe transient changes of up to 24 degrees in the phase of the water level response to the dilatational volumetric strain of the semidiurnal tidal components of wells at the Piñon Flat Observatory in Southern California. After the earthquakes, the phase gradually returns to the background value at a rate of less than 0.1 degrees per day. We use a model of axisymmetric flow driven by an imposed head oscillation through a single, laterally extensive, confined, homogeneous and isotropic aquifer to relate the phase response to aquifer properties. We interpret the changes in phase response as due to changes in permeability. At the time of the earthquakes, the permeability at the site increases by a factor as high as three. The permeability increase depends roughly linearly on the amplitude of seismic-wave peak ground velocity in the range of 0.21-2.1 cm s(-1). Such permeability increases are of interest to hydrologists and oil reservoir engineers as they affect fluid flow and might determine long-term evolution of hydrological and oil-bearing systems. They may also be interesting to seismologists, as the resulting pore pressure changes can affect earthquakes by changing normal stresses on faults. PMID:16810253

  7. The Permeable Classroom.

    ERIC Educational Resources Information Center

    Sandy, Leo R.

    1998-01-01

    Discusses the concept of permeability as knowledge flow into and out of the classroom and applies it to three college courses taught by the author at Plymouth State College (New Hampshire). Experiential knowledge comes into the classroom through interviews, guest speakers, and panel presentations, and flows out through service-learning students…

  8. Scales of rock permeability

    NASA Astrophysics Data System (ADS)

    Guéguen, Y.; Gavrilenko, P.; Le Ravalec, M.

    1996-05-01

    Permeability is a transport property which is currently measured in Darcy units. Although this unit is very convenient for most purposes, its use prevents from recognizing that permeability has units of length squared. Physically, the square root of permeability can thus be seen as a characteristic length or a characteristic pore size. At the laboratory scale, the identification of this characteristic length is a good example of how experimental measurements and theoretical modelling can be integrated. Three distinct identifications are of current use, relying on three different techniques: image analysis of thin sections, mercury porosimetry and nitrogen adsorption. In each case, one or several theoretical models allow us to derive permeability from the experimental data (equivalent channel models, statistical models, effective media models, percolation and network models). Permeability varies with pressure and temperature and this is a decisive point for any extrapolation to crustal conditions. As far as pressure is concerned, most of the effect is due to cracks and a model which does not incorporate this fact will miss its goal. Temperature induced modifications can be the result of several processes: thermal cracking (due to thermal expansion mismatch and anisotropy, or to fluid pressure build up), and pressure solution are the two main ones. Experimental data on pressure and temperature effects are difficult to obtain but they are urgently needed. Finally, an important issue is: up to which point are these small scale data and models relevant when considering formations at the oil reservoir scale, or at the crust scale? At larger scales the identification of the characteristic scale is also a major goal which is examined.

  9. EPA Permeable Surface Research - Poster

    EPA Science Inventory

    EPA recognizes permeable surfaces as an effective post-construction infiltration-based Best Management Practice to mitigate the adverse effects of stormwater runoff. The professional user community conceptually embraces permeable surfaces as a tool for making runoff more closely...

  10. Glutathione permeability of CFTR.

    PubMed

    Linsdell, P; Hanrahan, J W

    1998-07-01

    The cystic fibrosis transmembrane conductance regulator (CFTR) forms an ion channel that is permeable both to Cl- and to larger organic anions. Here we show, using macroscopic current recording from excised membrane patches, that the anionic antioxidant tripeptide glutathione is permeant in the CFTR channel. This permeability may account for the high concentrations of glutathione that have been measured in the surface fluid that coats airway epithelial cells. Furthermore, loss of this pathway for glutathione transport may contribute to the reduced levels of glutathione observed in airway surface fluid of cystic fibrosis patients, which has been suggested to contribute to the oxidative stress observed in the lung in cystic fibrosis. We suggest that release of glutathione into airway surface fluid may be a novel function of CFTR. PMID:9688865

  11. 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.

  12. Stainless Steel Permeability

    SciTech Connect

    Buchenauer, Dean A.; Karnesky, Richard A.

    2015-09-01

    An understanding of the behavior of hydrogen isotopes in materials is critical to predicting tritium transport in structural metals (at high pressure), estimating tritium losses during production (fission environment), and predicting in-vessel inventory for future fusion devices (plasma driven permeation). Current models often assume equilibrium diffusivity and solubility for a class of materials (e.g. stainless steels or aluminum alloys), neglecting trapping effects or, at best, considering a single population of trapping sites. Permeation and trapping studies of the particular castings and forgings enable greater confidence and reduced margins in the models. For FY15, we have continued our investigation of the role of ferrite in permeation for steels of interest to GTS, through measurements of the duplex steel 2507. We also initiated an investigation of the permeability in work hardened materials, to follow up on earlier observations of unusual permeability in a particular region of 304L forgings. Samples were prepared and characterized for ferrite content and coated with palladium to prevent oxidation. Issues with the poor reproducibility of measurements at low permeability were overcome, although the techniques in use are tedious. Funding through TPBAR and GTS were secured for a research grade quadrupole mass spectrometer (QMS) and replacement turbo pumps, which should improve the fidelity and throughput of measurements in FY16.

  13. Bovine colostrum supplementation during running training increases intestinal permeability.

    PubMed

    Buckley, Jonathan D; Butler, Ross N; Southcott, Emma; Brinkworth, Grant D

    2009-02-01

    Endurance exercise training can increase intestinal permeability which may contribute to the development of gastrointestinal symptoms in some athletes. Bovine colostrum (BC) supplementation reduces intestinal permeability induced by non-steroidal anti-inflammatory drugs. This study aimed to determine whether BC could also reduce intestinal permeability induced by endurance exercise. Thirty healthy adult males (25.0 ± 4.7 yr; mean ± SD) completed eight weeks of running three times per week for 45 minutes at their lactate threshold while consuming 60 g/day of BC, whey protein (WP) or control (CON). Intestinal permeability was assessed at baseline and after eight weeks by measuring the ratio of urinary lactulose (L) and rhamnose (R) excretion. After eight weeks the L/R ratio increased significantly more in volunteers consuming BC (251 ± 140%) compared with WP (21 ± 35%, P < 0.05) and CON (-7 ± 13%, P < 0.02). The increase in intestinal permeability with BC may have been due to BC inducing greater leakiness of tight junctions between enterocytes or by increasing macromolecular transport as it does in neonatal gut. Further research should investigate the potential for BC to increase intestinal macromolecular transport in adults. PMID:22253980

  14. Relative permeability through fractures

    SciTech Connect

    Diomampo, Gracel, P.

    2001-08-01

    The mechanism of two-phase flow through fractures is of importance in understanding many geologic processes. Currently, two-phase flow through fractures is still poorly understood. In this study, nitrogen-water experiments were done on both smooth and rough parallel plates to determine the governing flow mechanism for fractures and the appropriate methodology for data analysis. The experiments were done using a glass plate to allow visualization of flow. Digital video recording allowed instantaneous measurement of pressure, flow rate and saturation. Saturation was computed using image analysis techniques. The experiments showed that gas and liquid phases flow through fractures in nonuniform separate channels. The localized channels change with time as each phase path undergoes continues breaking and reforming due to invasion of the other phase. The stability of the phase paths is dependent on liquid and gas flow rate ratio. This mechanism holds true for over a range of saturation for both smooth and rough fractures. In imbibition for rough-walled fractures, another mechanism similar to wave-like flow in pipes was also observed. The data from the experiments were analyzed using Darcy's law and using the concept of friction factor and equivalent Reynold's number for two-phase flow. For both smooth- and rough-walled fractures a clear relationship between relative permeability and saturation was seen. The calculated relative permeability curves follow Corey-type behavior and can be modeled using Honarpour expressions. The sum of the relative permeabilities is not equal one, indicating phase interference. The equivalent homogeneous single-phase approach did not give satisfactory representation of flow through fractures. The graphs of experimentally derived friction factor with the modified Reynolds number do not reveal a distinctive linear relationship.

  15. Permeability across lipid membranes.

    PubMed

    Shinoda, Wataru

    2016-10-01

    Molecular permeation through lipid membranes is a fundamental biological process that is important for small neutral molecules and drug molecules. Precise characterization of free energy surface and diffusion coefficients along the permeation pathway is required in order to predict molecular permeability and elucidate the molecular mechanisms of permeation. Several recent technical developments, including improved molecular models and efficient sampling schemes, are illustrated in this review. For larger penetrants, explicit consideration of multiple collective variables, including orientational, conformational degrees of freedom, are required to be considered in addition to the distance from the membrane center along the membrane normal. Although computationally demanding, this method can provide significant insights into the molecular mechanisms of permeation for molecules of medical and pharmaceutical importance. This article is part of a Special Issue entitled: Biosimulations edited by Ilpo Vattulainen and Tomasz Róg. PMID:27085977

  16. Electrokinetic effects and fluid permeability

    NASA Astrophysics Data System (ADS)

    G. Berryman, James

    2003-10-01

    Fluid permeability of porous media depends mainly on connectivity of the pore space and two physical parameters: porosity and a pertinent length-scale parameter. Electrical imaging methods typically establish connectivity and directly measure electrical conductivity, which can then often be related to porosity by Archie's law. When electrical phase measurements are made in addition to the amplitude measurements, information about the pertinent length scale can then be obtained. Since fluid permeability controls the ability to flush unwanted fluid contaminants from the subsurface, inexpensive maps of permeability could improve planning strategies for remediation efforts. Detailed knowledge of fluid permeability is also important for oil field exploitation, where knowledge of permeability distribution in three dimensions is a common requirement for petroleum reservoir simulation and analysis, as well as for estimates on the economics of recovery.

  17. Water permeability of elastomers.

    PubMed

    Held, H R; Landi, S

    1977-01-01

    In a previous study it has been shown that the free moisture content in freeze-dried BCG vaccine dispensed in vials sealed with rubber stoppers increased during storage. The search for the source of this increase led us to explore the possibility that this additional moisture could originate from the rubber stoppers themselves. Therefore, the water permeability of various rubber stoppers has been studied, and the water content of grey butyl stoppers during some operations (autoclaving, oven-drying, freeze-drying, storage) used in the manufacturing of BCG vaccine has been determined. Our experiments showed: rapid water uptake during steam-autoclaving and rapid water release during subsequent oven-drying of the stoppers; a slow water uptake of the stoppers during freeze-drying and a slow water permeation through the stoppers when vials containing Indicating Drierite were stored in a water-saturated atmosphere. Among 12 types of rubber stoppers tested, the grey butyl stoppers and the silicone stoppers showed the lowest water uptake. Moisture-resistant wrappings decreased significantly the moisture uptake of Drierite. To delay moisture from reaching the vaccine it is recommended that the stoppers employed be as dry as possible. PMID:881425

  18. Permeable membrane experiment

    NASA Technical Reports Server (NTRS)

    Slavin, Thomas J.; Cao, Tuan Q.; Kliss, Mark H.

    1993-01-01

    The purpose of the Permeable Membrane Experiment is to gather flight data on three areas of membrane performance that are influenced by the presence of gravity. These areas are: (1) Liquid/gas phase separation, (2) gas bubble interference with diffusion through porous membranes and (3) wetting characteristics of hydrophilic membrane surfaces. These data are important in understaning the behavior of membrane/liquid/gas interfaces where surface tension forces predominate. The data will be compared with 1-g data already obtained and with predicted micrograviity behavior. The data will be used to develop designs for phase separation and plant nutrient delivery systems and will be available to the life support community for use in developing technologies which employ membranes. A conceptual design has been developed to conduct three membrane experiments, in sequence, aboard a single Complex Autonomous Payload (CAP) carrier to be carried in the Shuttle Orbiter payload bay. One experiment is conducted for each of the three membrane performance areas under study. These experiments are discussed in this paper.

  19. Relative Permeability of Fractured Rock

    SciTech Connect

    Mark D. Habana

    2002-06-30

    Contemporary understanding of multiphase flow through fractures is limited. Different studies using synthetic fractures and various fluids have yielded different relative permeability-saturation relations. This study aimed to extend the understanding of multiphase flow by conducting nitrogen-water relative permeability experiments on a naturally-fractured rock from The Geysers geothermal field. The steady-state approach was used. However, steady state was achieved only at the endpoint saturations. Several difficulties were encountered that are attributed to phase interference and changes in fracture aperture and surface roughness, along with fracture propagation/initiation. Absolute permeabilities were determined using nitrogen and water. The permeability values obtained change with the number of load cycles. Determining the absolute permeability of a core is especially important in a fractured rock. The rock may change as asperities are destroyed and fractures propagate or st rain harden as the net stresses vary. Pressure spikes occurred in water a solute permeability experiments. Conceptual models of an elastic fracture network can explain the pressure spike behavior. At the endpoint saturations the water relative permeabilities obtained are much less than the nitrogen gas relative permeabilities. Saturations were determined by weighing and by resistivity calculations. The resistivity-saturation relationship developed for the core gave saturation values that differ by 5% from the value determined by weighing. Further work is required to complete the relative permeability curve. The steady-state experimental approach encountered difficulties due to phase interference and fracture change. Steady state may not be reached until an impractical length of time. Thus, unsteady-state methods should be pursued. In unsteady-state experiments the challenge will be in quantifying rock fracture change in addition to fluid flow changes.

  20. Geothermal Permeability Enhancement - Final Report

    SciTech Connect

    Joe Beall; Mark Walters

    2009-06-30

    The overall objective is to apply known permeability enhancement techniques to reduce the number of wells needed and demonstrate the applicability of the techniques to other undeveloped or under-developed fields. The Enhanced Geothermal System (EGS) concept presented in this project enhances energy extraction from reduced permeability zones in the super-heated, vapor-dominated Aidlin Field of the The Geysers geothermal reservoir. Numerous geothermal reservoirs worldwide, over a wide temperature range, contain zones of low permeability which limit the development potential and the efficient recovery of heat from these reservoirs. Low permeability results from poorly connected fractures or the lack of fractures. The Enhanced Geothermal System concept presented here expands these technologies by applying and evaluating them in a systematic, integrated program.

  1. Respiratory mucosal permeability in asthma

    SciTech Connect

    Elwood, R.K.; Kennedy, S.; Belzberg, A.; Hogg, J.C.; Pare, P.D.

    1983-09-01

    The permeability of respiratory mucosa to technetium-labeled diethylenetriamine pentacetic acid (/sup 99m/Tc-DTPA) was measured in 10 clinically stable chronic asthmatics and the results were compared with those in 9 nonasthmatic control subjects. Nonspecific bronchial reactivity was measured using methacholine, and the PC20 was calculated. The intrapulmonary distribution and dose of the inhaled /sup 99m/Tc-DTPA was determined by a gamma camera and the half-life of the aerosolized label in the lung was calculated. The accumulation of radioactivity in the blood was monitored and a permeability index was calculated at 10, 25, and 60 min after aerosolization. Despite marked differences in airway reactivity, no differences in either parameter of permeability could be detected between the asthmatics and the control group. It is concluded that clinically stable asthmatics do not demonstrate increase mucosal permeability to small solutes when compared with normal subjects.

  2. Permeability within basaltic oceanic crust

    NASA Astrophysics Data System (ADS)

    Fisher, Andrew T.

    1998-05-01

    Water-rock interactions within the seafloor are responsible for significant energy and solute fluxes between basaltic oceanic crust and the overlying ocean. Permeability is the primary hydrologic property controlling the form, intensity, and duration of seafloor fluid circulation, but after several decades of characterizing shallow oceanic basement, we are still learning how permeability is created and distributed and how it changes as the crust ages. Core-scale measurements of basaltic oceanic crust yield permeabilities that are quite low (generally 10-22 to 10-17 m²), while in situ measurements in boreholes suggest an overlapping range of values extending several orders of magnitude higher (10-18 to 10-13 m²). Additional indirect estimates include calculations made from borehole temperature and flow meter logs (10-16 to 10-11 m²), numerical models of coupled heat and fluid flow at the ridge crest and within ridge flanks (10-16 to 10-9 m²), and several other methods. Qualitative indications of permeability within the basaltic oceanic crust come from an improved understanding of crustal stratigraphy and patterns of alteration and tectonic modification seen in ophiolites, seafloor samples and boreholes. Difficulties in reconciling the wide range of estimated permeabilities arise from differences in experimental scale and critical assumptions regarding the nature and distribution of fluid flow. Many observations and experimental and modeling results are consistent with permeability varying with depth into basement and with primary basement lithology. Permeability also seems to be highly heterogeneous and anisotropic throughout much of the basaltic crust, as within crystalline rocks in general. A series of focused experiments is required to resolve permeability in shallow oceanic basement and to directly couple upper crustal hydrogeology to magmatic, tectonic, and geochemical crustal evolution.

  3. Permeability of soils in Mississippi

    USGS Publications Warehouse

    O'Hara, Charles G.

    1994-01-01

    The permeability of soils in Mississippi was determined and mapped using a geographic information system (GIS). Soil permeabilities in Mississippi were determined to range in value from nearly 0.0 to values exceeding 5.0 inches per hour. The U.S. Soil Conservation Service's State Soil Geographic Data Base (STATSGO) was used as the primary source of data for the determination of area-weighted soil permeability. STATSGO provides soil layer properties that are spatially referenced to mapped areas. These mapped areas are referred to as polygons in the GIS. The polygons arc boundaries of soils mapped as a group and are given unique Map Unit Identifiers (MUIDs). The data describing the physical characteristics of the soils within each polygon are stored in a tabular data base format and are referred to as attributes. The U.S. Soil Conservation Service developed STATSGO to be primarily used as a guide for regional resource planning, management, and monitoring. STATSGO was designed so that soil information could be extracted from properties tables at the layer level, combined by component, and statistically expanded to cover the entire map unit. The results of this study provide a mapped value for permeability which is representative of the vertical permeability of soils in that area. The resultant permeability map provides a representative vertical soil permeability for a given area sufficient for county, multi- county, and area planning, and will be used as the soil permeability data component in the evaluation of the susceptibility of major aquifers to contami- nation in Mississippi.

  4. Permeability extraction: A sonic log inversion

    SciTech Connect

    Akbar, N.; Kim, J.J.

    1994-12-31

    In this paper the authors provide the missing important link between permeability and acoustic velocities by generating a permeability-dependent synthetic sonic log in a carbonate reservoir. The computations are based on Akbar`s theory that relates wave velocity to frequency, rock properties (e.g., lithology, permeability, and porosity), and fluid saturation and properties (viscosity, density, and compressibility). An inverted analytical expression of the theory is used to extract permeability from sonic velocity. The synthetic sonic and the computed permeability are compared with the observed sonic log and with plug permeability, respectively. The results demonstrate, as predicted by theory, that permeability can be related directly to acoustic velocities.

  5. Measuring Vascular Permeability In Vivo.

    PubMed

    Meijer, Eelco F J; Baish, James W; Padera, Timothy P; Fukumura, Dai

    2016-01-01

    Over the past decades, in vivo vascular permeability measurements have provided significant insight into vascular functions in physiological and pathophysiological conditions such as the response to pro- and anti-angiogenic signaling, abnormality of tumor vasculature and its normalization, and delivery and efficacy of therapeutic agents. Different approaches for vascular permeability measurements have been established. Here, we describe and discuss a conventional 2D imaging method to measure vascular permeability, which was originally documented by Gerlowski and Jain in 1986 (Microvasc Res 31:288-305, 1986) and further developed by Yuan et al. in the early 1990s (Microvasc Res 45:269-289, 1993; Cancer Res 54:352-3356, 1994), and our recently developed 3D imaging method, which advances the approach originally described by Brown et al. in 2001 (Nat Med 7:864-868, 2001). PMID:27581015

  6. Fibrinogen induces endothelial cell permeability

    PubMed Central

    Tyagi, Neetu; Roberts, Andrew M.; Dean, William L.; Tyagi, Suresh C.

    2010-01-01

    Many cardiovascular and cerebrovascular disorders are accompanied by an increased blood content of fibrinogen (Fg), a high molecular weight plasma adhesion protein. Fg is a biomarker of inflammation and its degradation products have been associated with microvascular leakage. We tested the hypothesis that at pathologically high levels, Fg increases endothelial cell (EC) permeability through extracellular signal regulated kinase (ERK) signaling and by inducing F-actin formation. In cultured ECs, Fg binding to intercellular adhesion molecule-1 and to α5β1 integrin, caused phosphorylation of ERK. Subsequently, F-actin formation increased and coincided with formation of gaps between ECs, which corresponded with increased permeability of ECs to albumin. Our data suggest that formation of F-actin and gaps may be the mechanism for increased albumin leakage through the EC monolayer. The present study indicates that elevated un-degraded Fg may be a factor causing microvascular permeability that typically accompanies cardiovascular and cerebrovascular disorders. PMID:17849175

  7. Permeability enhancement by shock cooling

    NASA Astrophysics Data System (ADS)

    Griffiths, Luke; Heap, Michael; Reuschlé, Thierry; Baud, Patrick; Schmittbuhl, Jean

    2015-04-01

    The permeability of an efficient reservoir, e.g. a geothermal reservoir, should be sufficient to permit the circulation of fluids. Generally speaking, permeability decreases over the life cycle of the geothermal system. As a result, is usually necessary to artificially maintain and enhance the natural permeability of these systems. One of the methods of enhancement -- studied here -- is thermal stimulation (injecting cold water at low pressure). This goal of this method is to encourage new thermal cracks within the reservoir host rocks, thereby increasing reservoir permeability. To investigate the development of thermal microcracking in the laboratory we selected two granites: a fine-grained (Garibaldi Grey granite, grain size = 0.5 mm) and a course-grained granite (Lanhelin granite, grain size = 2 mm). Both granites have an initial porosity of about 1%. Our samples were heated to a range of temperatures (100-1000 °C) and were either cooled slowly (1 °C/min) or shock cooled (100 °C/s). A systematic microstructural (2D crack area density, using standard stereological techniques, and 3D BET specific surface area measurements) and rock physical property (porosity, P-wave velocity, uniaxial compressive strength, and permeability) analysis was undertaken to understand the influence of slow and shock cooling on our reservoir granites. Microstructurally, we observe that the 2D crack surface area per unit volume and the specific surface area increase as a result of thermal stressing, and, for the same maximum temperature, crack surface area is higher in the shock cooled samples. This observation is echoed by our rock physical property measurements: we see greater changes for the shock cooled samples. We can conclude that shock cooling is an extremely efficient method of generating thermal microcracks and modifying rock physical properties. Our study highlights that thermal treatments are likely to be an efficient method for the "matrix" permeability enhancement of

  8. PERMEABILITY OF BACTERIAL SPORES I.

    PubMed Central

    Black, S. H.; Gerhardt, Philipp

    1961-01-01

    Black, S. H. (The University of Michigan, Ann Arbor) and Philipp Gerhardt. Permeability of bacterial spores. I. Characterization of glucose uptake. J. Bacteriol. 82:743–749. 1961.—The total uptake of glucose by masses of clean, dormant spores was measured to assess their permeability. After correction for intercellular space, packed spores of Bacillus cereus strain terminalis were found in 87 determinations to be permeated by glucose to 40% of their weight. The glucose uptake was relatively independent of environmental variables, and thus was concluded to occur principally through a process of passive diffusion. PMID:13869665

  9. High membrane permeability for melatonin.

    PubMed

    Yu, Haijie; Dickson, Eamonn J; Jung, Seung-Ryoung; Koh, Duk-Su; Hille, Bertil

    2016-01-01

    The pineal gland, an endocrine organ in the brain, synthesizes and secretes the circulating night hormone melatonin throughout the night. The literature states that this hormone is secreted by simple diffusion across the pinealocyte plasma membrane, but a direct quantitative measurement of membrane permeability has not been made. Experiments were designed to compare the cell membrane permeability to three indoleamines: melatonin and its precursors N-acetylserotonin (NAS) and serotonin (5-HT). The three experimental approaches were (1) to measure the concentration of effluxing indoleamines amperometrically in the bath while cells were being dialyzed internally by a patch pipette, (2) to measure the rise of intracellular indoleamine fluorescence as the compound was perfused in the bath, and (3) to measure the rate of quenching of intracellular fura-2 dye fluorescence as indoleamines were perfused in the bath. These measures showed that permeabilities of melatonin and NAS are high (both are uncharged molecules), whereas that for 5-HT (mostly charged) is much lower. Comparisons were made with predictions of solubility-diffusion theory and compounds of known permeability, and a diffusion model was made to simulate all of the measurements. In short, extracellular melatonin equilibrates with the cytoplasm in 3.5 s, has a membrane permeability of ∼1.7 µm/s, and could not be retained in secretory vesicles. Thus, it and NAS will be "secreted" from pineal cells by membrane diffusion. Circumstances are suggested when 5-HT and possibly catecholamines may also appear in the extracellular space passively by membrane diffusion. PMID:26712850

  10. Permeability of compacting porous lavas

    NASA Astrophysics Data System (ADS)

    Ashwell, P. A.; Kendrick, J. E.; Lavallée, Y.; Kennedy, B. M.; Hess, K.-U.; Aulock, F. W.; Wadsworth, F. B.; Vasseur, J.; Dingwell, D. B.

    2015-03-01

    The highly transient nature of outgassing commonly observed at volcanoes is in part controlled by the permeability of lava domes and shallow conduits. Lava domes generally consist of a porous outer carapace surrounding a denser lava core with internal shear zones of variable porosity. Here we examine densification using uniaxial compression experiments on variably crystalline and porous rhyolitic dome lavas from the Taupo Volcanic Zone. Experiments were conducted at 900°C and an applied stress of 3 MPa to 60% strain, while monitoring acoustic emissions to track cracking. The evolution of the porous network was assessed via X-ray computed tomography, He-pycnometry, and relative gas permeability. High starting connected porosities led to low apparent viscosities and high strain rates, initially accompanied by abundant acoustic emissions. As compaction ensued, the lavas evolved; apparent viscosity increased and strain rate decreased due to strain hardening of the suspensions. Permeability fluctuations resulted from the interplay between viscous flow and brittle failure. Where phenocrysts were abundant, cracks had limited spatial extent, and pore closure decreased axial and radial permeability proportionally, maintaining the initial anisotropy. In crystal-poor lavas, axial cracks had a more profound effect, and permeability anisotropy switched to favor axial flow. Irrespective of porosity, both crystalline samples compacted to a threshold minimum porosity of 17-19%, whereas the crystal-poor sample did not achieve its compaction limit. This indicates that unconfined loading of porous dome lavas does not necessarily form an impermeable plug and may be hindered, in part by the presence of crystals.

  11. High membrane permeability for melatonin

    PubMed Central

    Yu, Haijie; Dickson, Eamonn J.; Jung, Seung-Ryoung; Koh, Duk-Su

    2016-01-01

    The pineal gland, an endocrine organ in the brain, synthesizes and secretes the circulating night hormone melatonin throughout the night. The literature states that this hormone is secreted by simple diffusion across the pinealocyte plasma membrane, but a direct quantitative measurement of membrane permeability has not been made. Experiments were designed to compare the cell membrane permeability to three indoleamines: melatonin and its precursors N-acetylserotonin (NAS) and serotonin (5-HT). The three experimental approaches were (1) to measure the concentration of effluxing indoleamines amperometrically in the bath while cells were being dialyzed internally by a patch pipette, (2) to measure the rise of intracellular indoleamine fluorescence as the compound was perfused in the bath, and (3) to measure the rate of quenching of intracellular fura-2 dye fluorescence as indoleamines were perfused in the bath. These measures showed that permeabilities of melatonin and NAS are high (both are uncharged molecules), whereas that for 5-HT (mostly charged) is much lower. Comparisons were made with predictions of solubility-diffusion theory and compounds of known permeability, and a diffusion model was made to simulate all of the measurements. In short, extracellular melatonin equilibrates with the cytoplasm in 3.5 s, has a membrane permeability of ∼1.7 µm/s, and could not be retained in secretory vesicles. Thus, it and NAS will be “secreted” from pineal cells by membrane diffusion. Circumstances are suggested when 5-HT and possibly catecholamines may also appear in the extracellular space passively by membrane diffusion. PMID:26712850

  12. Quantifying Evaporation in a Permeable Pavement System

    EPA Science Inventory

    Studies quantifying evaporation from permeable pavement systems are limited to a few laboratory studies and one field application. This research quantifies evaporation for a larger-scale field application by measuring the water balance from lined permeable pavement sections. Th...

  13. Permeable Pavement Research - Edison, New Jersey

    EPA Science Inventory

    This presentation provides the background and summary of results collected at the permeable pavement parking lot monitored at the EPA facility in Edison, NJ. This parking lot is surfaced with permeable interlocking concrete pavers (PICP), pervious concrete, and porous asphalt. ...

  14. Novel additives to retard permeable flow

    SciTech Connect

    Golombok, Michael; Crane, Carel; Ineke, Erik; Welling, Marco; Harris, Jon

    2008-09-15

    Low concentrations of surfactant and cosolute in water, can selectively retard permeable flow in high permeability rocks compared to low permeability ones. This represents a way forward for more efficient areal sweep efficiency when water flooding a reservoir during improved oil recovery. (author)

  15. Review of hydrogen isotope permeability through materials

    SciTech Connect

    Steward, S.A.

    1983-08-15

    This report is the first part of a comprehensive summary of the literature on hydrogen isotope permeability through materials that do not readily form hydrides. While we mainly focus on pure metals with low permeabilities because of their importance to tritium containment, we also give data on higher-permeability materials such as iron, nickel, steels, and glasses.

  16. Vapor-liquid phase separator permeability results

    NASA Technical Reports Server (NTRS)

    Yuan, S. W. K.; Frederking, T. H. K.

    1981-01-01

    Continued studies are described in the area of vapor-liquid phase separator work with emphasis on permeabilities of porous sintered plugs (stainless steel, nominal pore size 2 micrometer). The temperature dependence of the permeability has been evaluated in classical fluid using He-4 gas at atmospheric pressure and in He-2 on the basis of a modified, thermosmotic permeability of the normal fluid.

  17. Structure/Permeability Relationships Of Polyimide Membranes

    NASA Technical Reports Server (NTRS)

    St. Clair, A. K.; Yamamoto, H.; Mi, Y.; Stern, S. A.

    1995-01-01

    Report describes experimental study of permeabilities, by each of five gases, of membranes made of four different polyimides. Conducted to gain understanding of effects of molecular structures of membranes on permeabilities and to assess potential for exploitation of selective permeability in gas-separation processes. Gases used: H2, O2, N2, CO2, and CH4.

  18. Permeability enhancement using explosive techniques

    SciTech Connect

    Adams, T.F.; Schmidt, S.C.; Carter, W.J.

    1980-01-01

    In situ recovery methods for many of our hydrocarbon and mineral resources depend on the ability to create or enhance permeability in the resource bed to allow uniform and predictable flow. To meet this need, a new branch of geomechanics devoted to computer prediction of explosive rock breakage and permeability enhancement has developed. The computer is used to solve the nonlinear equations of compressible flow, with the explosive behavior and constitutive properties of the medium providing the initial/boundary conditions and material response. Once the resulting computational tool has been verified and calibrated with appropriate large-scale field tests, it can be used to develop and optimize commercially useful explosive techniques for in situ resource recovery.

  19. Scale-dependent permeability of fractured andesite

    NASA Astrophysics Data System (ADS)

    Heap, Michael; Kennedy, Ben

    2016-04-01

    Extension fractures in volcanic systems exist on all scales, from microscopic fractures to large fissures. They play a fundamental role in the movement of fluids and distribution of pore pressure, and therefore exert considerable influence over volcanic eruption recurrence. We present here laboratory permeability measurements for porous (porosity = 0.03-0.6) andesites before (i.e. intact) and after failure in tension (i.e., the samples host a throughgoing tensile fracture). The permeability of the intact andesites increases with increasing porosity, from 2 × 10-17 to 5 × 10-11 m2. Following fracture formation, the permeability of the samples (the effective permeability) falls within a narrow range regardless of their initial porosity: 2-6 × 10-11 m2. However, laboratory measurements of fractured samples likely overestimate the effective permeability due to the inherent scale-dependence of permeability. To better understand this scale-dependence, we first determined the permeability of the tensile fractures using a two-dimensional model that considers flow in parallel layers. Our calculations highlight that tensile fractures in low-porosity samples are more permeable (as high as 2.3 × 10-9 m2) than those in high-porosity samples (as low as 3.0 × 10-10 m2), a difference that can be explained by an increase in fracture tortuosity with porosity. We then use our fracture permeability data to model the effective permeability of rock with different host rock permeabilities (10-17 to 10-11 m2) populated by tensile fractures over a wide range of lengthscale. We find that the effective permeability of fractured andesite depends heavily on the initial host rock permeability and the scale of interest. At a given lengthscale, the effective permeability of high-permeability rock (10-12 to 10-11 m2) is essentially unaffected by the presence of numerous tensile fractures. By contrast, a single tensile fracture increases the effective permeability of low-permeability rock

  20. Steam-water relative permeability

    SciTech Connect

    Ambusso, W.; Satik, C.; Home, R.N.

    1997-12-31

    A set of relative permeability relations for simultaneous flow of steam and water in porous media have been measured in steady state experiments conducted under the conditions that eliminate most errors associated with saturation and pressure measurements. These relations show that the relative permeabilities for steam-water flow in porous media vary approximately linearly with saturation. This departure from the nitrogen/water behavior indicates that there are fundamental differences between steam/water and nitrogen/water flows. The saturations in these experiments were measured by using a high resolution X-ray computer tomography (CT) scanner. In addition the pressure gradients were obtained from the measurements of liquid phase pressure over the portions with flat saturation profiles. These two aspects constitute a major improvement in the experimental method compared to those used in the past. Comparison of the saturation profiles measured by the X-ray CT scanner during the experiments shows a good agreement with those predicted by numerical simulations. To obtain results that are applicable to general flow of steam and water in porous media similar experiments will be conducted at higher temperature and with porous rocks of different wetting characteristics and porosity distribution.

  1. Vortex rings impinging on permeable boundaries

    NASA Astrophysics Data System (ADS)

    Mujal-Colilles, Anna; Dalziel, Stuart B.; Bateman, Allen

    2015-01-01

    Experiments with vortex rings impinging permeable and solid boundaries are presented in order to investigate the influence of permeability. Utilizing Particle Image Velocimetry, we compared the behaviour of a vortex ring impinging four different reticulated foams (with permeability k ˜ 26 - 85 × 10-8 m2) and a solid boundary. Results show how permeability affects the stretching phenomena of the vortex ring and the formation and evolution of the secondary vortex ring with opposite sign. Moreover, permeability also affects the macroscopic no-slip boundary condition found on the solid boundary, turning it into an apparent slip boundary condition for the most permeable boundary. The apparent slip-boundary condition and the flux exchange between the ambient fluid and the foam are jointly responsible for both the modified formation of the secondary vortex and changes on the vortex ring diameter increase.

  2. Permeability and corrosion behavior of phenoxy coatings

    SciTech Connect

    Tiburcio, A.C.; Manson, J.A.

    1993-12-31

    The corrosion behavior of a glass-bead-filled phenoxy coating system was studied by correlating permeability and electrochemical measurements with actual corrosion performance. The study emphasized the effects of filler and filler/polymer matrix interactions on corrosion behavior. Water vapor permeability, dissolved oxygen permeability and conductivity measurements were made to determine the rate of transport of the three key ingredients in cathodic delamination and corrosion process (H{sub 2}O, O{sub 2}, and cation). The glass bead filler had a greater effect on both cathodic delamination and corrosion behavior than filler/polymer matrix interaction. Overall, the permeability behavior controlled the delamination and corrosion performance.

  3. Permeability-porosity data sets for sandstones

    USGS Publications Warehouse

    Nelson, P.H.

    2004-01-01

    Due to the variable nature of permeability-porosity relations, core should be obtained and permeability (k) and porosity (??) should be determined on core plugs in the laboratory for the formation of interest. A catalog of k versus (??) data sets is now available on the Web. Examples from the catalog are considered to illustrate some aspects of k versus ?? dependencies in siliciclastic reservoirs.

  4. Pressure sensitivity of low permeability sandstones

    USGS Publications Warehouse

    Kilmer, N.H.; Morrow, N.R.; Pitman, J.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.

  5. Effect of Dead Algae on Soil Permeability

    SciTech Connect

    Harvey, R.S.

    2003-02-21

    Since existing basins support heavy growths of unicellular green algae which may be killed by temperature variation or by inadvertent pH changes in waste and then deposited on the basin floor, information on the effects of dead algae on soil permeability was needed. This study was designed to show the effects of successive algal kills on the permeability of laboratory soil columns.

  6. Intestinal permeability and contractility in murine colitis.

    PubMed Central

    van Meeteren, M E; van Bergeijk, J D; van Dijk, A P; Tak, C J; Meijssen, M A; Zijlstra, F J

    1998-01-01

    We developed an in vitro organ bath method to measure permeability and contractility simultaneously in murine intestinal segments. To investigate whether permeability and contractility are correlated and influenced by mucosal damage owing to inflammation, BALB/c mice were exposed to a 10% dextran sulphate sodium (DSS) solution for 8 days to induce colitis. The effect of pharmacologically induced smooth muscle relaxation and contraction on permeability was tested in vitro. Regional permeability differences were observed in both control and 10% DSS-treated mice. Distal colon segments were less permeable to 3H-mannitol and 14C-PEG 400 molecules compared with proximal colon and ileum. Intestinal permeability in control vs. 10% DSS mice was not altered, although histologic inflammation score and IFN-gamma pro-inflammatory cytokine levels were significantly increased in proximal and distal colon. IL-1beta levels were enhanced in these proximal and distal segments, but not significantly different from controls. Any effect of pharmacologically induced contractility on intestinal permeability could not be observed. In conclusion, intestinal permeability and contractility are not correlated in this model of experimentally induced colitis in mice. Although simultaneous measurement in a physiological set-up is possible, this method has to be further validated. PMID:9705603

  7. Accurate determination of characteristic relative permeability curves

    NASA Astrophysics Data System (ADS)

    Krause, Michael H.; Benson, Sally M.

    2015-09-01

    A recently developed technique to accurately characterize sub-core scale heterogeneity is applied to investigate the factors responsible for flowrate-dependent effective relative permeability curves measured on core samples in the laboratory. The dependency of laboratory measured relative permeability on flowrate has long been both supported and challenged by a number of investigators. Studies have shown that this apparent flowrate dependency is a result of both sub-core scale heterogeneity and outlet boundary effects. However this has only been demonstrated numerically for highly simplified models of porous media. In this paper, flowrate dependency of effective relative permeability is demonstrated using two rock cores, a Berea Sandstone and a heterogeneous sandstone from the Otway Basin Pilot Project in Australia. Numerical simulations of steady-state coreflooding experiments are conducted at a number of injection rates using a single set of input characteristic relative permeability curves. Effective relative permeability is then calculated from the simulation data using standard interpretation methods for calculating relative permeability from steady-state tests. Results show that simplified approaches may be used to determine flowrate-independent characteristic relative permeability provided flow rate is sufficiently high, and the core heterogeneity is relatively low. It is also shown that characteristic relative permeability can be determined at any typical flowrate, and even for geologically complex models, when using accurate three-dimensional models.

  8. 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.

  9. Relating P-wave attenuation to permeability

    SciTech Connect

    Akbar, N.; Dvorkin, J.; Nur, A. . Dept. of Geophysics)

    1993-01-01

    To relate P-wave attenuation to permeability, the authors examine a three-dimensional (3-D) theoretical model of a cylindrical pore filled with viscous fluid and embedded in an infinite isotropic elastic medium. They calculate both attenuation and permeability as functions of the direction of wave propagation. Attenuation estimates are based on the squirt flow mechanism; permeability is calculated using the Kozeny-Carmen relation. They find that in the case when a plane P-wave propagates parallel to this orientation (Q[sup [minus]1][delta] = 90[degree]), attenuation is always higher than when a wave propagates parallel to this orientation (Q[sup [minus]1][delta] = 0[degree]). The ratio of these two attenuation values Q[sup [minus]1][delta] = 90[degree]/Q[sup [minus]1] = 0[degree] increases with an increasing pore radius and decreasing frequency and saturation. By changing permeability, varying the radius of the pore, they find that the permeability-attenuation relation is characterized by a peak that shifts toward lower permeabilities as frequency decreases. Therefore, the attenuation of a low-frequency wave decreases with increasing permeability. They observe a similar trend on relations between attenuation and permeability experimentally obtained on sandstone samples.

  10. A method of determination of permeability

    SciTech Connect

    Kuznetsov, S.V.; Trofimov, V.A.

    2007-11-15

    A method is proposed for determining permeability of coals under conditions of steady-state deformation and stationary filtration mode by employing a reference core made of gas-non-sorbing material with a known permeability. The approach has been developed to assess the time of transition to the stable filtration.

  11. Compact rock material gas permeability properties

    NASA Astrophysics Data System (ADS)

    Wang, Huanling; Xu, Weiya; Zuo, Jing

    2014-09-01

    Natural compact rocks, such as sandstone, granite, and rock salt, are the main materials and geological environment for storing underground oil, gas, CO2, shale gas, and radioactive waste because they have extremely low permeabilities and high mechanical strengths. Using the inert gas argon as the fluid medium, the stress-dependent permeability and porosity of monzonitic granite and granite gneiss from an underground oil storage depot were measured using a permeability and porosity measurement system. Based on the test results, models for describing the relationships among the permeability, porosity, and confining pressure of rock specimens were analyzed and are discussed. A power law is suggested to describe the relationship between the stress-dependent porosity and permeability; for the monzonitic granite and granite gneiss (for monzonitic granite (A-2), the initial porosity is approximately 4.05%, and the permeability is approximately 10-19 m2; for the granite gneiss (B-2), the initial porosity is approximately 7.09%, the permeability is approximately 10-17 m2; and the porosity-sensitivity exponents that link porosity and permeability are 0.98 and 3.11, respectively). Compared with moderate-porosity and high-porosity rocks, for which φ > 15%, low-porosity rock permeability has a relatively lower sensitivity to stress, but the porosity is more sensitive to stress, and different types of rocks show similar trends. From the test results, it can be inferred that the test rock specimens' permeability evolution is related to the relative particle movements and microcrack closure.

  12. Permeability of naturally fractured reservoirs

    SciTech Connect

    Teufel, L.W. )

    1991-03-01

    Hydraulic fracture stress data collected from carbonate and clastic reservoirs show that the minimum horizontal in situ stress decreases with reservoir depletion and pore pressure drawdown. The reduction in minimum horizontal stress is, in part, a poro-elastic effect that is linear with pore pressure drawdown and can be approximated by an unlaxial compaction model. The observed change in horizontal stress is equal to 40% to 80% of the net change in pore pressure. This type of stress behavior has important implications for reservoir management of naturally fractured reservoirs, because conductivity of fractures is highly stress sensitive. Laboratory studies clearly demonstrate that with increasing effective normal stress fracture apertures close and conductivity decreases. Accordingly, in sharp contrast to the standard procedure, predictions of changes in fracture permeability during reservoir depletion should not be made simply as a function of pore pressure drawdown, but more importantly should be based on how the effective in situ stresses change during drawdown and the orientation of natural fractures relative to the in situ stress field. The increase in the effective overburden stress will be the largest and equal to the magnitude of the pore pressure decline because the overburden stress is constant and does not change with drawdown. However, the increase in the effective minimum horizontal stress will be much smaller. Accordingly, for a reservoir with several sets of fractures with similar morphology, the reduction in fracture conductivity during drawdown will be greatest for horizontal fractures and least for vertical fractures aligned with the maximum horizontal stress direction.

  13. A Poroelastic Description of Permeability Evolution

    NASA Astrophysics Data System (ADS)

    Hassanzadegan, Alireza; Zimmermann, Günter

    2014-07-01

    Pore pressure changes in a geothermal reservoir, as a result of injection and/or production of water, result in changes of stress acting on the reservoir rock and, consequently, changes in the mechanical and transport properties of the rock. Bulk modulus and permeability were measured at different pressures and temperatures. An outcropping equivalent of Rotliegend reservoir rock in the North German Basin (Flechtinger sandstone) was used to perform hydrostatic tests and steady state fluid flow tests. Permeability measurements were conducted while cycling confining pressure; the dependence of permeability on stress was determined at a constant downstream pressure of 1 MPa. Also, temperature was increased stepwise from 30 to 140 °C and crack porosity was calculated at different temperatures. Although changes in the volumes of cracks are not significant, the cracks control fluid flow pathways and, consequently, the permeability of the rock. A new model was derived which relates microstructure of porosity, the stress-strain curve, and permeability. Porosity change was described by the first derivative of the stress-strain curve. Permeability evolution was ascribed to crack closure and was related to the second derivative of the stress-strain curve. The porosity and permeability of Flechtinger sandstone were reduced by increasing the effective pressure and decreased after each pressure cycle.

  14. Fluid permeability of deformable fracture networks

    SciTech Connect

    Brown, S.R.; Bruhn, R.L.

    1997-04-01

    The authors consider the problem of defining the fracture permeability tensor for each grid lock in a rock mass from maps of natural fractures. For this purpose they implement a statistical model of cracked rock due to M. Oda [1985], where the permeability tensor is related to the crack geometry via a volume average of the contribution from each crack in the population. In this model tectonic stress is implicitly coupled to fluid flow through an assumed relationship between crack aperture and normal stress across the crack. The authors have included the following enhancements to the basic model: (1) a realistic model of crack closure under stress has been added along with the provision to apply tectonic stresses to the fracture system in any orientation, the application of stress results in fracture closure and consequently a reduction in permeability; (2) the fracture permeability can be superimposed onto an arbitrary anisotropic matrix permeability; (3) the fracture surfaces are allowed to slide under the application of shear stress, causing fractures to dilate and result in a permeability increase. Through an example, the authors demonstrate that significant changes in permeability magnitudes and orientations are possible when tectonic stress is applied to a fracture system.

  15. Permeable Gas Flow Influences Magma Fragmentation Speed.

    NASA Astrophysics Data System (ADS)

    Richard, D.; Scheu, B.; Spieler, O.; Dingwell, D.

    2008-12-01

    Highly viscous magmas undergo fragmentation in order to produce the pyroclastic deposits that we observe, but the mechanisms involved remain unclear. The overpressure required to initiate fragmentation depends on a number of physical parameters, such as the magma's vesicularity, permeability, tensile strength and textural properties. It is clear that these same parameters control also the speed at which a fragmentation front travels through magma when fragmentation occurs. Recent mathematical models of fragmentation processes consider most of these factors, but permeable gas flow has not yet been included in these models. However, it has been shown that permeable gas flow through a porous rock during a sudden decompression event increases the fragmentation threshold. Fragmentation experiments on natural samples from Bezymianny (Russia), Colima (Mexico), Krakatau (Indonesia) and Augustine (USA) volcanoes confirm these results and suggest in addition that high permeable flow rates may increase the speed of fragmentation. Permeability from the investigated samples ranges from as low as 5 x 10-14 to higher than 9 x 10- 12 m2 and open porosity ranges from 16 % to 48 %. Experiments were performed for each sample series at applied pressures up to 35 MPa. Our results indicate that the rate of increase of fragmentation speed is higher when the permeability is above 10-12 m2. We confirm that it is necessary to include the influence of permeable flow on fragmentation dynamics.

  16. Using magnetic permeability bits to store information

    NASA Astrophysics Data System (ADS)

    Timmerwilke, John; Petrie, J. R.; Wieland, K. A.; Mencia, Raymond; Liou, Sy-Hwang; Cress, C. D.; Newburgh, G. A.; Edelstein, A. S.

    2015-10-01

    Steps are described in the development of a new magnetic memory technology, based on states with different magnetic permeability, with the capability to reliably store large amounts of information in a high-density form for decades. The advantages of using the permeability to store information include an insensitivity to accidental exposure to magnetic fields or temperature changes, both of which are known to corrupt memory approaches that rely on remanent magnetization. The high permeability media investigated consists of either films of Metglas 2826 MB (Fe40Ni38Mo4B18) or bilayers of permalloy (Ni78Fe22)/Cu. Regions of films of the high permeability media were converted thermally to low permeability regions by laser or ohmic heating. The permeability of the bits was read by detecting changes of an external 32 Oe probe field using a magnetic tunnel junction 10 μm away from the media. Metglas bits were written with 100 μs laser pulses and arrays of 300 nm diameter bits were read. The high and low permeability bits written using bilayers of permalloy/Cu are not affected by 10 Mrad(Si) of gamma radiation from a 60Co source. An economical route for writing and reading bits as small at 20 nm using a variation of heat assisted magnetic recording is discussed.

  17. Permeability Barrier Generation in the Martian Lithosphere

    NASA Astrophysics Data System (ADS)

    Schools, Joe; Montési, Laurent

    2015-11-01

    Permeability barriers develop when a magma produced in the interior of a planet rises into the cooler lithosphere and crystallizes more rapidly than the lithosphere can deform (Sparks and Parmentier, 1991). Crystallization products may then clog the porous network in which melt is propagating, reducing the permeability to almost zero, i.e., forming a permeability barrier. Subsequent melts cannot cross the barrier. Permeability barriers have been useful to explain variations in crustal thickness at mid-ocean ridges on Earth (Magde et al., 1997; Hebert and Montési, 2011; Montési et al., 2011). We explore here under what conditions permeability barriers may form on Mars.We use the MELTS thermodynamic calculator (Ghiorso and Sack, 1995; Ghiorso et al., 2002; Asimow et al., 2004) in conjunction with estimated Martian mantle compositions (Morgan and Anders, 1979; Wänke and Dreibus, 1994; Lodders and Fegley, 1997; Sanloup et al., 1999; Taylor 2013) to model the formation of permeability barriers in the lithosphere of Mars. In order to represent potential past and present conditions of Mars, we vary the lithospheric thickness, mantle potential temperature (heat flux), oxygen fugacity, and water content.Our results show that permeability layers can develop in the thermal boundary layer of the simulated Martian lithosphere if the mantle potential temperature is higher than ~1500°C. The various Martian mantle compositions yield barriers in the same locations, under matching variable conditions. There is no significant difference in barrier location over the range of accepted Martian oxygen fugacity values. Water content is the most significant influence on barrier development as it reduces the temperature of crystallization, allowing melt to rise further into the lithosphere. Our lower temperature and thicker lithosphere model runs, which are likely the most similar to modern Mars, show no permeability barrier generation. Losing the possibility of having a permeability

  18. Effective permeabilities for model heterogeneous porous media

    SciTech Connect

    Otevo, C.; Rusinek, I. ); Saez, A.E. )

    1990-01-01

    This paper presents a technique to evaluate effective absolute permeabilities for heterogeneous porous media. The technique is based on a perturbation analysis of the equations of motion of a slightly compressible fluid in a homogeneous porous medium at low Reynolds numbers. The effective permeabilities can be calculated once the local geometry of the heterogeneous medium is specified. The technique is used to evaluate two- and three-dimensional effective vertical permeabilities in porous media with shale intercalations, including the case in which the porous matrix is anisotropic.

  19. Gas Permeable Chemochromic Compositions for Hydrogen Sensing

    NASA Technical Reports Server (NTRS)

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

  20. Flexible Sandwich Diaphragms Are Less Permeable

    NASA Technical Reports Server (NTRS)

    Michalovic, John G.; Vassallo, Franklin A.

    1993-01-01

    Diaphragms for use in refrigerator compressors made as laminates of commercially available elastomers and metals. Diaphragms flexible, but less permeable by chlorofluorocarbon refrigerant fluids than diaphragms made of homogeneous mixtures of materials.

  1. Variability of permeability with diameter of conduit

    NASA Astrophysics Data System (ADS)

    Adegoke, J. A.; Olowofela, J. A.

    2008-05-01

    An entry length is always observed before laminar flow is achieved in fluid flowing in a conduit. This depends on the Reynolds number of the flow and the degree of smoothness of the conduit. This work examined this region and the point where laminar flow commences in the context of flow through conduit packed with porous material like beads, of known porosity. Using some theoretical assumptions, it is demonstrated that permeability varies from zero at wall-fluid boundary to maximum at mid-stream, creating a permeability profile similar to the velocity profile. An equation was obtained to establish this. We also found that peak values of permeability increase with increasing porosity, and therefore entry length increases with increasing porosity with all other parameters kept constant. A plot of peak permeability versus porosity revealed that they are linearly related.

  2. Method for determining permeability in hydrocarbon wells

    SciTech Connect

    Boone, D.E.

    1990-10-09

    This patent describes a method of determining at the earth's surface the permeability of a subsurface earth formation having a known nominal hydrocarbon pore saturation value. The formation is tranversed by a borehole resulting from drilling with a drill bit.

  3. Specific surface area model for foam permeability.

    PubMed

    Pitois, O; Lorenceau, E; Louvet, N; Rouyer, F

    2009-01-01

    Liquid foams were recognized early to be porous materials, as liquid flowed between the gas bubbles. Drainage theories have been established, and foam permeability has been modeled from the microscopic description of the equivalent pores geometry, emphasizing similarities with their solid counterparts. But to what extent can the theoretical work devoted to the permeability of solid porous materials be useful to liquid foams? In this article, the applicability of the Carman-Kozeny model on foam is investigated. We performed measurements of the permeability of foams with nonmobile surfactants, and we show that, in introducing an equivalent specific surface area for the foam, the model accurately describes the experimental data over two orders of magnitude for the foam liquid fraction, without any additional parameters. Finally, it is shown that this model includes the previous permeability models derived for foams in the dry foams limit. PMID:19032030

  4. NASA In-step: Permeable Membrane Experiment

    NASA Technical Reports Server (NTRS)

    1992-01-01

    Viewgraphs on the Permeable Membrane Experiment are presented. An experiment overview is given. The Membrane Phase Separation Experiment, Membrane Diffusion Interference Experiment, and Membrane Wetting Experiment are described. Finally, summary and conclusions are discussed.

  5. Permeability After Impact Testing of Composite Laminates

    NASA Technical Reports Server (NTRS)

    Nettles, Alan T.

    2003-01-01

    Since composite laminates are beginning to be identified for use in reusable launch vehicle propulsion systems, an understanding of their permeance is needed. A foreign object impact event can cause a localized area of permeability (leakage) in a polymer matrix composite and it is the aim of this study to assess a method of quantifying permeability-after-impact results. A simple test apparatus is presented and variables that could affect the measured values of permeability-after-impact were assessed. Once it was determined that valid numbers were being measured, a fiber/resin system was impacted at various impact levels and the resulting permeability measured, first with a leak check solution (qualitative) then using the new apparatus (quantitative). The results showed that as the impact level increased, so did the measured leakage. As the pressure to the specimen was increased, the leak rate was seen to increase in a non-linear fashion for almost all of the specimens tested.

  6. Permeability After Impact Testing of Composite Laminates

    NASA Technical Reports Server (NTRS)

    Nettles, A.T.; Munafo, Paul (Technical Monitor)

    2002-01-01

    Since composite laminates are beginning to be identified for use in reusable launch vehicle propulsion systems, an understanding of their permeance is needed. A foreign object impact event can cause a localized area of permeability (leakage) in a polymer matrix composite and it is the aim of this study to assess a method of quantifying permeability-after-impact results. A simple test apparatus is presented and variables that could affect the measured values of permeability-after-impact were assessed. Once it was determined that valid numbers were being measured, a fiber/resin system was impacted at various impact levels and the resulting permeability measured, first with a leak check solution (qualitative) then using the new apparatus (quantitative). The results showed that as the impact level increased, so did the measured leakage. As the pressure to the specimen was increased, the leak rate was seen to increase in a non-linear fashion for almost all of the specimens tested.

  7. Measuring Permeability of Composite Cryotank Laminants

    NASA Technical Reports Server (NTRS)

    Oliver, Stanley T.; Selvidge, Shawn; Watwood, Michael C.

    2004-01-01

    This paper describes a test method developed to identify whether certain materials and material systems are suitable candidates for large pressurized reusable cryogenic tanks intended for use in current and future manned launch systems. It provides a quick way to screen numerous candidate materials for permeability under anticipated loading environments consistent with flight conditions, as well as addressing reusability issues. cryogenic tank, where the major design issue was hydrogen permeability. It was successfully used to evaluate samples subjected to biaxial loading while maintaining test temperatures near liquid hydrogen. After each sample was thermally preconditioned, a cyclic pressure load was applied to simulate the in-plane strain. First permeability was measured while a sample was under load. Then the sample was unloaded and allowed to return to ambient temperature. The test was repeated to simulate reusability, in order to evaluate its effects on material permeability.

  8. Permeability of rayon based polymer composites

    NASA Technical Reports Server (NTRS)

    Stokes, E. H.

    1992-01-01

    Several types of anomalous rayon based phenolic behavior have been observed in post-fired nozzles and exit cones. Many of these events have been shown to be related to the development of internal gas pressure within the material. The development of internal gas pressure is a function of the amount of gas produced within the material and the rate at which that gas is allowed to escape. The latter property of the material is referred to as the material's permeability. The permeability of two dimensional carbonized rayon based phenolic composites is a function of material direction, temperature, and stress/strain state. Recently significant differences in the permeability of these materials has been uncovered which may explain their inconsistent performance. This paper summarizes what is known about the permeability of these materials to date and gives possible implications of these finding to the performance of these materials in an ablative environment.

  9. Lunar electrical conductivity and magnetic permeability

    NASA Technical Reports Server (NTRS)

    Dyal, P.; Parkin, C. W.; Daily, W. D.

    1975-01-01

    Improved analytical techniques are applied to a large Apollo magnetometer data set to yield values of electroconductivity, temperature, magnetic permeability, and iron abundance. Average bulk electroconductivity of the moon is calculated to be .0007 mho/m; a rapid increase with depth to about .003 mho/m within 250 km is indicated. The temperature profile, obtained from the electroconductivity profile for olivine, indicates high lunar temperatures at relatively shallow depths. Magnetic permeability of the moon relative to its environment is calculated to be 1.008 plus or minus .005; a permeability relative to free space of 1.012 plus 0.011, minus 0.008 is obtained. Lunar iron abundances corresponding to this permeability value are 2.5 plus 2.3, minus 1.7 wt% free iron and 5.0-13.5 wt% total iron for a moon composed of a combination of free iron, olivine, and orthopyroxene.

  10. PERMEABILITY OF POLYMERIC MEMBRANE LINING MATERIALS

    EPA Science Inventory

    Permeabilities to three gases (carbon dioxide, methane, and nitrogen), water vapor, and five solvents (methanol, acetone, cyclohexane, xylene, and chloroform) are reported for a broad range of commercial polymeric membranes. Gas and water vapor transmission (WVT) data were determ...

  11. Vascular permeability, vascular hyperpermeability and angiogenesis

    PubMed Central

    Nagy, Janice A.; Benjamin, Laura; Zeng, Huiyan; Dvorak, Ann M.

    2008-01-01

    The vascular system has the critical function of supplying tissues with nutrients and clearing waste products. To accomplish these goals, the vasculature must be sufficiently permeable to allow the free, bidirectional passage of small molecules and gases and, to a lesser extent, of plasma proteins. Physiologists and many vascular biologists differ as to the definition of vascular permeability and the proper methodology for its measurement. We review these conflicting views, finding that both provide useful but complementary information. Vascular permeability by any measure is dramatically increased in acute and chronic inflammation, cancer, and wound healing. This hyperpermeability is mediated by acute or chronic exposure to vascular permeabilizing agents, particularly vascular permeability factor/vascular endothelial growth factor (VPF/VEGF, VEGF-A). We demonstrate that three distinctly different types of vascular permeability can be distinguished, based on the different types of microvessels involved, the composition of the extravasate, and the anatomic pathways by which molecules of different size cross-vascular endothelium. These are the basal vascular permeability (BVP) of normal tissues, the acute vascular hyperpermeability (AVH) that occurs in response to a single, brief exposure to VEGF-A or other vascular permeabilizing agents, and the chronic vascular hyperpermeability (CVH) that characterizes pathological angiogenesis. Finally, we list the numerous (at least 25) gene products that different authors have found to affect vascular permeability in variously engineered mice and classify them with respect to their participation, as far as possible, in BVP, AVH and CVH. Further work will be required to elucidate the signaling pathways by which each of these molecules, and others likely to be discovered, mediate the different types of vascular permeability. PMID:18293091

  12. Pneumatic fracturing of low permeability media

    SciTech Connect

    Schuring, J.R.

    1996-08-01

    Pneumatic fracturing of soils to enhance the removal and treatment of dense nonaqueous phase liquids is described. The process involves gas injection at a pressure exceeding the natural stresses and at a flow rate exceeding the permeability of the formation. The paper outlines geologic considerations, advantages and disadvantages, general technology considerations, low permeability media considerations, commercial availability, efficiency, and costs. Five case histories of remediation using pneumatic fracturing are briefly summarized. 11 refs., 2 figs., 1 tab.

  13. Fracture-permeability behavior of shale

    SciTech Connect

    Carey, J. William; Lei, Zhou; Rougier, Esteban; Mori, Hiroko; Viswanathan, Hari

    2015-05-08

    The fracture-permeability behavior of Utica shale, an important play for shale gas and oil, was investigated using a triaxial coreflood device and X-ray tomography in combination with finite-discrete element modeling (FDEM). Fractures generated in both compression and in a direct-shear configuration allowed permeability to be measured across the faces of cylindrical core. Shale with bedding planes perpendicular to direct-shear loading developed complex fracture networks and peak permeability of 30 mD that fell to 5 mD under hydrostatic conditions. Shale with bedding planes parallel to shear loading developed simple fractures with peak permeability as high as 900 mD. In addition to the large anisotropy in fracture permeability, the amount of deformation required to initiate fractures was greater for perpendicular layering (about 1% versus 0.4%), and in both cases activation of existing fractures are more likely sources of permeability in shale gas plays or damaged caprock in CO₂ sequestration because of the significant deformation required to form new fracture networks. FDEM numerical simulations were able to replicate the main features of the fracturing processes while showing the importance of fluid penetration into fractures as well as layering in determining fracture patterns.

  14. Simulating perforation permeability damage and cleanup

    SciTech Connect

    Morris, J P; Lomov, I N; Glenn, L A

    2000-12-15

    Completion of cased and cemented wells by shaped charge perforation causes its own damage to the formation, potentially reducing well productivity. In practice it is found that underbalance conditions clean up the damaged zone to some extent, however, the mechanisms of these processes are poorly understood. Most hydrocodes typically used to simulate rock response to shaped charge penetration do not provide permeability estimates. Furthermore, the time scales for formation clean up are potentially much longer than the period of jet penetration. We have developed a simple, yet accurate model for the evolution of porosity and permeability which can easily be incorporated into existing hydrocodes using information from the history of each cell. In addition, we have developed a code that efficiently simulates fines migration during the post-shot surge period using initial conditions taken directly from hydrocode simulations of jet penetration. Results from a one-dimensional model simulation are in excellent agreement with measured permeability distributions. We also present two-dimensional numerical results which qualitatively reproduce experimentally obtained permeability maps for different values of underbalance. Although initial results have been promising, further comparison with experiment is essential to tune the coupling between the hydrocode and fines migration simulator. Currently the permeability model is most appropriate for high permeability sandstones (such as Berea), but with little effort, the model can be extended to other rock types, given sufficient experimental data.

  15. Simulating Perforation Permeability Damage and Cleanup

    SciTech Connect

    Morris, J.P.; Lomov, I.N.; Glenn, L.A.

    2000-09-01

    Completion of cased and cemented wells by shaped charge perforation causes its own damage to the formation, potentially reducing well productivity. In practice it is found that underbalance conditions clean up the damaged zone to some extent, however, the mechanisms of these processes are poorly understood. Most hydrocodes typically used to simulate rock response to shaped charge penetration do not provide permeability estimates. Furthermore, the time scales for formation clean up are potentially much longer than the period of jet penetration. We have developed a simple, yet accurate model for the evolution of porosity and permeability which can easily be incorporated into existing hydrocodes using information from the history of each cell. In addition, we have developed a code that efficiently simulates fines migration during the post-shot surge period using initial conditions taken directly from hydrocode simulations of jet penetration. Results from a one-dimensional model simulation are in excellent agreement with measured fines and permeability distributions. We also present two-dimensional numerical results which qualitatively reproduce experimentally obtained permeability maps for different values of underbalance. Although initial results have been promising, further comparison with experiment is essential to tune the coupling between the hydrocode and fines migration simulator. Currently the permeability model is most appropriate for high permeability sandstones (such as Berea), but with little effort, the model can be extended to other rock types, given sufficient experimental data.

  16. Fracture-permeability behavior of shale

    DOE PAGESBeta

    Carey, J. William; Lei, Zhou; Rougier, Esteban; Mori, Hiroko; Viswanathan, Hari

    2015-05-08

    The fracture-permeability behavior of Utica shale, an important play for shale gas and oil, was investigated using a triaxial coreflood device and X-ray tomography in combination with finite-discrete element modeling (FDEM). Fractures generated in both compression and in a direct-shear configuration allowed permeability to be measured across the faces of cylindrical core. Shale with bedding planes perpendicular to direct-shear loading developed complex fracture networks and peak permeability of 30 mD that fell to 5 mD under hydrostatic conditions. Shale with bedding planes parallel to shear loading developed simple fractures with peak permeability as high as 900 mD. In addition tomore » the large anisotropy in fracture permeability, the amount of deformation required to initiate fractures was greater for perpendicular layering (about 1% versus 0.4%), and in both cases activation of existing fractures are more likely sources of permeability in shale gas plays or damaged caprock in CO₂ sequestration because of the significant deformation required to form new fracture networks. FDEM numerical simulations were able to replicate the main features of the fracturing processes while showing the importance of fluid penetration into fractures as well as layering in determining fracture patterns.« less

  17. Hormonal Regulation of Nuclear Permeability*◆

    PubMed Central

    O'Brien, Elizabeth M.; Gomes, Dawidson A.; Sehgal, Sona; Nathanson, Michael H.

    2010-01-01

    Transport into the nucleus is critical for regulation of gene transcription and other intranuclear events. Passage of molecules into the nucleus depends in part upon their size and the presence of appropriate targeting sequences. However, little is known about the effects of hormones or their second messengers on transport across the nuclear envelope. We used localized, two-photon activation of a photoactivatable green fluorescent protein to investigate whether hormones, via their second messengers, could alter nuclear permeability. Vasopressin other hormones that increase cytosolic Ca2+ and activate protein kinase C increased permeability across the nuclear membrane of SKHep1 liver cells in a rapid unidirectional manner. An increase in cytosolic Ca2+ was both necessary and sufficient for this process. Furthermore, localized photorelease of caged Ca2+ near the nuclear envelope resulted in a local increase in nuclear permeability. Neither activation nor inhibition of protein kinase C affected nuclear permeability. These findings provide evidence that hormones linking to certain G protein-coupled receptors increase nuclear permeability via cytosolic Ca2+. Short term regulation of nuclear permeability may provide a novel mechanism by which such hormones permit transcription factors and other regulatory molecules to enter the nucleus, thereby regulating gene transcription in target cells. PMID:17158097

  18. Cell permeability beyond the rule of 5.

    PubMed

    Matsson, Pär; Doak, Bradley C; Over, Björn; Kihlberg, Jan

    2016-06-01

    Drug discovery for difficult targets that have large and flat binding sites is often better suited to compounds beyond the "rule of 5" (bRo5). However, such compounds carry higher pharmacokinetic risks, such as low solubility and permeability, and increased efflux and metabolism. Interestingly, recent drug approvals and studies suggest that cell permeable and orally bioavailable drugs can be discovered far into bRo5 space. Tactics such as reduction or shielding of polarity by N-methylation, bulky side chains and intramolecular hydrogen bonds may be used to increase cell permeability in this space, but often results in decreased solubility. Conformationally flexible compounds can, however, combine high permeability and solubility, properties that are keys for cell permeability and intestinal absorption. Recent developments in computational conformational analysis will aid design of such compounds and hence prediction of cell permeability. Transporter mediated efflux occurs for most investigated drugs in bRo5 space, however it is commonly overcome by high local intestinal concentrations on oral administration. In contrast, there is little data to support significant impact of transporter-mediated intestinal absorption in bRo5 space. Current knowledge of compound properties that govern transporter effects of bRo5 drugs is limited and requires further fundamental and comprehensive studies. PMID:27067608

  19. Permeability properties of erythrocyte ghosts.

    PubMed

    TEORELL, T

    1952-05-01

    1. Erythrocyte ghosts from human blood were produced by gentle water hemolysis. The ghost-containing hemolysate (about 20 mN) was added to media of different composition (KCl, NaCl, glucose, sucrose, etc.) and varying concentration ranging from 8 to 840 mN. The volume changes of the ghost cells were followed by a light absorption method. The potassium and sodium concentrations were also analyzed in some representative cases. 2. The ghosts shrank, or swelled, in two stages. An initial phase with a momentary expulsion, or uptake, of water leading to an osmotic equilibrium, was followed by a second phase in which a slow swelling or shrinking proceeded toward a final constant volume. 3. The ghosts were semipermeable in the sense that water always passed rapidly in either direction so as to maintain isotonicity with the external medium. The relation between ghost cell volumes (V) and the total concentration (C(e)) of the suspension medium can be expressed by a modified van't Hoff-Mariotte law: (C(e) + a)(V - b) = constant. Here a is a term correcting for an internal pressure and b is the non-solvent volume of the ghost cells. This means that the ghosts behave as perfect osmometers. 4. On the other hand appreciable concentration differences of the K and Na ions could be maintained across the intact ghost cell membranes for long periods. Whether this phenomenon is due simply to very low cation permeability or to active transport processes cannot be decided, although the first assumption appears more probable. 5. When the ghosts were treated with small concentrations of a lytic substance like Na oleate, the alkali ion transfer was greatly increased. This seems to be a simple exchange diffusion process with simultaneous, continued maintenance of osmotic equilibrium (= the second phase). A simplified theory is also given for the kinetics of the volume variations and ion exchange during the second phase (cf. the Appendix). 6. Miscellaneous observations on the effects of p

  20. Comparative field permeability measurement of permeable pavements using ASTM C1701 and NCAT permeameter methods.

    PubMed

    Li, Hui; Kayhanian, Masoud; Harvey, John T

    2013-03-30

    Fully permeable pavement is gradually gaining support as an alternative best management practice (BMP) for stormwater runoff management. As the use of these pavements increases, a definitive test method is needed to measure hydraulic performance and to evaluate clogging, both for performance studies and for assessment of permeability for construction quality assurance and maintenance needs assessment. Two of the most commonly used permeability measurement tests for porous asphalt and pervious concrete are the National Center for Asphalt Technology (NCAT) permeameter and ASTM C1701, respectively. This study was undertaken to compare measured values for both methods in the field on a variety of permeable pavements used in current practice. The field measurements were performed using six experimental section designs with different permeable pavement surface types including pervious concrete, porous asphalt and permeable interlocking concrete pavers. Multiple measurements were performed at five locations on each pavement test section. The results showed that: (i) silicone gel is a superior sealing material to prevent water leakage compared with conventional plumbing putty; (ii) both methods (NCAT and ASTM) can effectively be used to measure the permeability of all pavement types and the surface material type will not impact the measurement precision; (iii) the permeability values measured with the ASTM method were 50-90% (75% on average) lower than those measured with the NCAT method; (iv) the larger permeameter cylinder diameter used in the ASTM method improved the reliability and reduced the variability of the measured permeability. PMID:23434738

  1. Permeability reduction in granite under hydrothermal conditions

    USGS Publications Warehouse

    Morrow, C.A.; Moore, Diane E.; Lockner, D.A.

    2001-01-01

    The formation of impermeable fault seals between earthquake events is a feature of many models of earthquake generation, suggesting that earthquake recurrence may depend in part on the rate of permeability reduction of fault zone materials under hydrothermal conditions. In this study, permeability measurements were conducted on intact, fractured, and gouge-bearing Westerly granite at an effective pressure of 50 MPa and at temperatures from 150?? to 500??C, simulating conditions in the earthquake-generating portions of fault zones. Pore fluids were cycled back and forth under a 2 MPa pressure differential for periods of up to 40 days. Permeability of the granite decreased with time t, following the exponential relation k = c(10-rt). For intact samples run between 250?? and 500??C the time constant for permeability decrease r was proportional to temperature and ranged between 0.001 and 0.1 days-1 (i.e., between 0.4 and 40 decades year-1 loss of permeability). Values of r for the lower-temperature experiments differed little from the 250??C runs. In contrast, prefractured samples showed higher rates of permeability decrease at a given temperature. The surfaces of the fractured samples showed evidence of dissolution and mineral growth that increased in abundance with both temperature and time. The experimentally grown mineral assemblages varied with temperature and were consistent with a rock-dominated hydrothermal system. As such mineral deposits progressively seal the fractured samples, their rates of permeability decrease approach the rates for intact rocks at the same temperature. These results place constraints on models of precipitation sealing and suggest that fault rocks may seal at a rate consistent with earthquake recurrence intervals of typical fault zones.

  2. Strain-dependent permeability of volcanic rocks.

    NASA Astrophysics Data System (ADS)

    Farquharson, Jamie; Heap, Michael; Baud, Patrick

    2016-04-01

    We explore permeability evolution during deformation of volcanic materials using a suite of rocks with varying compositions and physical properties (such as porosity ϕ). 40 mm × 20 mm cylindrical samples were made from a range of extrusive rocks, including andesites from Colima, Mexico (ϕ˜0.08; 0.18; 0.21), Kumamoto, Japan (ϕ˜0.13), and Ruapehu, New Zealand (ϕ˜0.15), and basalt from Mt Etna, Italy (ϕ˜0.04). Gas permeability of each sample was measured before and after triaxial deformation using a steady-state benchtop permeameter. To study the strain-dependence of permeability in volcanic rocks, we deformed samples to 2, 3, 4, 6, and 12 % axial strain at a constant strain rate of 10‑5 s‑1. Further, the influence of failure mode - dilatant or compactant - on permeability was assessed by repeating experiments at different confining pressures. During triaxial deformation, porosity change of the samples was monitored by a servo-controlled pore fluid pump. Below an initial porosity of ˜0.18, and at low confining pressures (≤ 20 MPa), we observe a dilatant failure mode (shear fracture formation). With increasing axial strain, stress is accommodated by fault sliding and the generation of ash-sized gouge between the fracture planes. In higher-porosity samples, or at relatively higher confining pressures (≥ 60 MPa), we observe compactant deformation characterised by a monotonous decrease in porosity with increasing axial strain. The relative permeability k' is given by the change in permeability divided by the initial reference state. When behaviour is dilatant, k' tends to be positive: permeability increases with progressive deformation. However, results suggest that after a threshold amount of strain, k' can decrease. k' always is negative (permeability decreases during deformation) when compaction is the dominant behaviour. Our results show that - in the absence of a sealing or healing process - the efficiency of a fault to transmit fluids is

  3. Gastrointestinal permeability in patients with irritable bowel syndrome assessed using a four probe permeability solution

    PubMed Central

    Del Valle-Pinero, Arseima Y.; Van Deventer, Hendrick E.; Fourie, Nicolaas H.; Martino, Angela C.; Patel, Nayan S.; Remaley, Alan T.; Henderson, Wendy A.

    2013-01-01

    Background Abnormal gastrointestinal permeability has been linked to irritable bowel syndrome (IBS). The lactulose-to-mannitol ratio is traditionally used to assess small intestine permeability while sucralose and sucrose are used to assess colonic and gastric permeability respectively. We used a single 4-probe test solution to assess permeability throughout the gastrointestinal tract in IBS patients and healthy controls by measuring the recovery of the probes in urine after ingestion using a modified liquid chromatography mass spectrometry protocol. Methods Fasting participants (N = 59) drank a permeability test solution (100 ml: sucralose, sucrose, mannitol, and lactulose). Urine was collected over a 5-h period and kept frozen until analysis. Urinary sugar concentrations were measured using an liquid chromatography/triple quadruple mass spectrometer. Results Colonic permeability was significantly lower in IBS patients when compared to healthy controls (p = 0.011). Gastric and small intestinal permeability did not significantly differ between the groups. Conclusions The study demonstrates the clinical potential of this non-invasive method for assessing alterations in gastrointestinal permeability in patients with IBS. PMID:23328210

  4. Quantitative Permeability Prediction for Anisotropic Porous Media

    NASA Astrophysics Data System (ADS)

    Sheng, Q.; Thompson, K. E.

    2012-12-01

    Pore-scale modeling as a predictive tool has become an integral to both research and commercial simulation in recent years. Permeability is one of the most important of the many properties that can be simulated. Traditionally, permeability is determined using Darcy's law, based on the assumption that the pressure gradient is aligned with the principal flow direction. However, a wide variety of porous media exhibit anisotropic permeability due to particle orientation or laminated structure. In these types of materials, the direction of fluid flow is not aligned with the pressure gradient (except along the principal directions). Thus, it is desirable to predict the full permeability tensor for anisotropic materials using a first-principles pore-scale approach. In this work, we present a fast method to determine the full permeability tensor and the principal directions using a novel network modeling algorithm. We also test the ability of network modeling (which is an approximate method) to detect anisotropy in various structures. Both computational fluid dynamics (CFD) methods and network modeling have emerged as effective techniques to predict rock properties. CFD models are more rigorous but computationally expensive. Network modeling involves significant approximations but can be orders-of-magnitude more efficient computationally, which is important for both speed and the ability to model larger scales. This work uses network modeling, with simulations performed on two types of anisotropic materials: laminated packings (with layers of different sized particles) and oriented packings (containing particles with preferential orientation). Pore network models are created from the porous media data, and a novel method is used to determine the permeability tensor and principal flow direction using pore network modeling. The method is verified by comparing the calculated principal directions with the known anisotropy and also by comparing permeability with values from CFD

  5. Gas Permeability in Rubbery Polyphosphazene Membranes

    SciTech Connect

    Frederick F. Stewart; Christopher J. Orme; John R. Klaehn; Mason K. Harrup; Thomas A. Luther; Eric S. Peterson

    2006-09-01

    The synthesis, characterization, and gas permeability of ten new polyphosphazenes has been studied. Additionally, the first gas permeation data has been collected on hydrolytically unstable poly[bis-(chloro)phosphazene]. Gases used in this study include CO2, CH4, O2, N2, H2, and Ar. CO2 was the most permeable gas through any of the phosphazenes and a direct correlation between the Tg of the polymer and CO2 transport was noted with permeability increasing with decreasing polymer Tg. To a lesser degree, permeability of all the other gases studied also yielded increases with decreasing polymer Tg. The trend observed for these new polymers was further supported by published data for other phosphazenes. Furthermore, permeability data for all gases were found to correlate to the gas condensability and the gas critical pressures, except for hydrogen, suggesting that the nature of the gas is also a significant factor for permeation through rubbery phosphazene membranes. Ideal separation factors (á) for the CO2/H2 and CO2/CH4 gas pairs were calculated. For CO2/CH4, no increase in á was observed with decreasing Tg, however increases in á were noted for the CO2/H2 pair.

  6. Honeycomb Core Permeability Under Mechanical Loads

    NASA Technical Reports Server (NTRS)

    Glass, David E.; Raman, V. V.; Venkat, Venki S.; Sankaran, Sankara N.

    1997-01-01

    A method for characterizing the air permeability of sandwich core materials as a function of applied shear stress was developed. The core material for the test specimens was either Hexcel HRP-3/16-8.0 and or DuPont Korex-1/8-4.5 and was nominally one-half inch thick and six inches square. The facesheets where made of Hercules' AS4/8552 graphite/epoxy (Gr/Ep) composites and were nominally 0.059-in. thick. Cytec's Metalbond 1515-3M epoxy film adhesive was used for co-curing the facesheets to the core. The permeability of the specimens during both static (tension) and dynamic (reversed and non-reversed) shear loads were measured. The permeability was measured as the rate of air flow through the core from a circular 1-in2 area of the core exposed to an air pressure of 10.0 psig. In both the static and dynamic testing, the Korex core experienced sudden increases in core permeability corresponding to a core catastrophic failure, while the URP core experienced a gradual increase in the permeability prior to core failure. The Korex core failed at lower loads than the HRP core both in the transverse and ribbon directions.

  7. Changes in permeability caused by earthquakes

    NASA Astrophysics Data System (ADS)

    Manga, Michael; Wang, Chi-Yuen; Shi, Zheming

    2016-04-01

    Earthquakes induce a range of hydrological responses, including changes in streamflow and changes in the water level in wells. Here we show that many of these responses are caused the changes in permeability produced by the passage of seismic waves. First we analyze streams that were dry or nearly dry before the 2014 M6 Napa, California, earthquake butstarted to flow after the earthquake. We show that the new flows were meteoric in origin and originate in the nearby mountains. Responses are not correlated with the sign of static strains implying seismic waves liberated this water, presumably by changing permeability. We also analyze a large network of wells in China that responded to 4 large earthquakes. We monitor permeability changes through their effect on the water level response to solid Earth tides. We find that when earthquakes produce sustained changes in water level, permeability also changes. Wells with water level changes that last for only days show no evidence for changes in aquifer permeability.

  8. Permeability of Rigid Fibrous Refractory Insulations

    NASA Technical Reports Server (NTRS)

    Marschall, J.; Milos, F. S.; Rasky, Daniel J. (Technical Monitor)

    1996-01-01

    Rigid fibrous refractory insulations (TPS tiles) are integral components of many spacecraft thermal protection systems. These materials are composed of refractory fibers With diameters on the order of 1 to 15 micrometers. They are lightweight and have an open, highly porous microstructure. Typical densities are less than 500 kilograms per cubic meters, and porosities generally exceed 0.8. Because of their open porosity, these materials are permeable to gas glow. There are numerous instances in which internal gas transport in a thermal protection system could be important; examples include the penetration of hot boundary-layer gases into the insulation, the flow of decomposition (pyrolysis) products from the interior, the use of convective flows to mitigate ice formation caused by cryopumping, and the design of refractory vents for pressure equilibration during atmospheric entry. Computational analysis of gas flow through porous media requires values of permeability which have not previously been available for the rigid fibrous insulations used in thermal protection systems. This paper will document measurements of permeability for a variety of insulations from NASA's LI, FRCI, and AETB families of lightweight ceramic ablators. The directional anisotropy of permeability and its dependence on gas pressure and material density will be presented. It will be shown that rarified-flow effects are significant in the flow through such materials. Connections will be drawn between the insulation microstructure and permeability. The paper will also include representative computations of flow through rigid fibrous insulations.

  9. Comparison of Steady State Method and Transient Methods for Water Permeability Measurement in Low Permeability Rocks

    NASA Astrophysics Data System (ADS)

    Boulin, P. F.; Bretonnier, P.; Gland, N.

    2010-12-01

    Very low permeability geomaterials (order of nanoDarcy (10-21 m2)), such as clays rocks, are studied for many industrial applications such as production from unconventional reserves of oil and gas, CO2 geological storage and deep geological disposal of high-level long-lived nuclear wastes. For these last two applications, clay efficiency as barrier relies mainly on their very low permeability. Laboratory measurement of low permeability to water (below 10-19 m2) remains a technical challenge. Some authors argue that steady state methods are irrelevant due to the time required to stabilize water fluxes in such low permeability media. Most of the authors measuring low permeabilities use a transient technique called pulse decay. This study aims to compare objectively these different types of permeability tests performed on a single clay sample. For the steady state method, a high precision pump was used to impose a pressure gradient and to measure the small resulting water flow rate at steady state. We show that with a suitable set-up, the steady state method enables to measure a very low permeability of 8 10-22 m2 in a period of three days. For a comparable duration, the pulse decay test, most commonly used for such low permeability measurements, provides only an average estimate of the permeability. Permeability measurements by pulse decay require to perform simulations to interpret the pressure relaxation signals. Many uncertainties remain such as the determination of the reservoirs storage factor, micro leakage effect, or the determination of the initial pulse pressure. All these uncertainties have a very significant impact on the determination of sample permeability and specific storage. Opposite to the wide-spread idea that transient techniques are required to measure very low permeability, we show that direct steady state measurement of water permeability with suitable equipments can be much faster and more accurate than measurement by pulse decay, especially in

  10. GROUNDWATER FLOW IN LOW-PERMEABILITY ENVIRONMENTS.

    USGS Publications Warehouse

    Neuzil, C.E.

    1986-01-01

    Certain geologic media are known to have small permeability; subsurface environments composed of these media and lacking well developed secondary permeability have groundwater flow systems with many distinctive characteristics. Moreover, groundwater flow in these environments appears to influence the evolution of certain hydrologic, geologic, and geochemical systems, may affect the accumulation of petroleum and ores, and probably has a role in the structural evolution of parts of the crust. Such environments are also important in the context of waste disposal. This review attempts to synthesize the diverse contributions of various disciplines to the problem of flow in low-permeability environments. Problems hindering analysis are enumerated together with suggested approaches to overcoming them. A common thread running through the discussion is the significance of size- and time-scale limitations of the ability to directly observe flow behavior and make significance of size- and time-scale limitations of the ability to directly observe flow behavior and make measurements of parameters.

  11. Permeability of Hollow Microspherical Membranes to Helium

    NASA Astrophysics Data System (ADS)

    Zinoviev, V. N.; Kazanin, I. V.; Pak, A. Yu.; Vereshchagin, A. S.; Lebiga, V. A.; Fomin, V. M.

    2016-01-01

    This work is devoted to the study of the sorption characteristics of various hollow microspherical membranes to reveal particles most suitable for application in the membrane-sorption technologies of helium extraction from a natural gas. The permeability of the investigated sorbents to helium and their impermeability to air and methane are shown experimentally. The sorption-desorption dependences of the studied sorbents have been obtained, from which the parameters of their specific permeability to helium are calculated. It has been established that the physicochemical modification of the original particles exerts a great influence on the coefficient of the permeability of a sorbent to helium. Specially treated cenospheres have displayed high efficiency as membranes for selective extraction of helium.

  12. The effect of heat on skin permeability

    PubMed Central

    Park, Jung-Hwan; Lee, Jeong-Woo; Kim, Yeu-Chun; Prausnitz, Mark R.

    2008-01-01

    Although the effects of long exposure (≫ 1 s) to moderate temperatures (≤ 100 °C) have been well characterized, recent studies suggest that shorter exposure (< 1 s) to higher temperatures (> 100 °C) can dramatically increase skin permeability. Previous studies suggest that by keeping exposures short, thermal damage can be localized to the stratum corneum without damaging deeper tissue. Initial clinical trials have progressed to Phase II (see http://clinicaltrials.gov), which indicates the procedure can be safe. Because the effect of heating under these conditions has received little systematic or mechanistic study, we heated full-thickness skin, epidermis and stratum corneum samples from human and porcine cadavers to temperatures ranging from 100°C to 315°C for times ranging from 100 ms to 5 s. Tissue samples were analyzed using skin permeability measurements, differential scanning calorimetry, thermomechanical analysis, thermal gravimetric analysis, brightfield and confocal microscopy, and histology. Skin permeability was shown to be a very strong function of temperature and a less strong function of the duration of heating. At optimal conditions used in this study, transdermal delivery of calcein was increased up to 760-fold by rapidly heating the skin at high temperature. More specifically, skin permeability was increased (I) by a few fold after heating to approximately 100°C – 150°C, (II) by one to two orders of magnitude after heating to approximately 150°C – 250°C and (III) by three orders of magnitude after heating above 300°C. These permeability changes were attributed to (I) disordering of stratum corneum lipid structure, (II) disruption of stratum corneum keratin network structure and (III) decomposition and vaporization of keratin to create micron-scale holes in the stratum corneum, respectively. We conclude that heating the skin with short, high temperature pulses can increase skin permeability by orders of magnitude due to structural

  13. In-situ permeability determining method

    SciTech Connect

    Dowling, D.J.; Arnold, D.M.; Richter, A.P. Jr.; Warren, W.F.

    1985-01-29

    A method of determining the permeability of a particular stratum in an earth formation traversed by a borehole includes injecting a liquid into the borehole at a first pressure thereby causing liquid flow into the stratum. A first flow rate of the liquid is determined at the first pressure. The pressure of the liquid being injected into the borehole is then changed to a second pressure level and a second flow rate of the liquid flowing into the stratum is determined at the second pressure. An indication of the permeability of the stratum is then derived in accordance with the two pressures, the two flow rates and known characteristics of the stratum.

  14. Development of an Improved Permeability Modification Simulator

    SciTech Connect

    Gao, H.W.; Elphnick, J.

    1999-03-09

    This report describes the development of an improved permeability modification simulator performed jointly by BDM Petroleum Technologies and Schlumberger Dowell under a cooperative research and development agreement (CRADA) with the US Department of Energy. The improved simulator was developed by modifying NIPER's PC-GEL permeability modification simulator to include a radial model, a thermal energy equation, a wellbore simulator, and a fully implicit time-stepping option. The temperature-dependent gelation kinetics of a delayed gel system (DGS) is also included in the simulator.

  15. Water Permeability of Asymmetric Planar Lipid Bilayers

    PubMed Central

    Krylov, Andrey V.; Pohl, Peter; Zeidel, Mark L.; Hill, Warren G.

    2001-01-01

    To understand how plasma membranes may limit water flux, we have modeled the apical membrane of MDCK type 1 cells. Previous experiments demonstrated that liposomes designed to mimic the inner and outer leaflet of this membrane exhibited 18-fold lower water permeation for outer leaflet lipids than inner leaflet lipids (Hill, W.G., and M.L. Zeidel. 2000. J. Biol. Chem. 275:30176–30185), confirming that the outer leaflet is the primary barrier to permeation. If leaflets in a bilayer resist permeation independently, the following equation estimates single leaflet permeabilities: 1/PAB = 1/PA + 1/PB (Eq. l), where PAB is the permeability of a bilayer composed of leaflets A and B, PA is the permeability of leaflet A, and PB is the permeability of leaflet B. Using for the MDCK leaflet–specific liposomes gives an estimated value for the osmotic water permeability (Pf) of 4.6 × 10−4 cm/s (at 25°C) that correlated well with experimentally measured values in intact cells. We have now constructed both symmetric and asymmetric planar lipid bilayers that model the MDCK apical membrane. Water permeability across these bilayers was monitored in the immediate membrane vicinity using a Na+-sensitive scanning microelectrode and an osmotic gradient induced by addition of urea. The near-membrane concentration distribution of solute was used to calculate the velocity of water flow (Pohl, P., S.M. Saparov, and Y.N. Antonenko. 1997. Biophys. J. 72:1711–1718). At 36°C, Pf was 3.44 ± 0.35 × 10−3 cm/s for symmetrical inner leaflet membranes and 3.40 ± 0.34 × 10−4 cm/s for symmetrical exofacial membranes. From , the estimated permeability of an asymmetric membrane is 6.2 × 10−4 cm/s. Water permeability measured for the asymmetric planar bilayer was 6.7 ± 0.7 × 10−4 cm/s, which is within 10% of the calculated value. Direct experimental measurement of Pf for an asymmetric planar membrane confirms that leaflets in a bilayer offer independent and additive resistances to

  16. Lunar magnetic permeability studies and magnetometer sensitivity

    NASA Technical Reports Server (NTRS)

    King, J. H.; Ness, N. F.

    1977-01-01

    A regression of quiet magnetic field components simultaneously measured by the two Explorer 35 magnetometers reveals uncertainties in effective sensitivity factors of up to a few percent in one or both of these instruments. Given this, the validity of previous lunar permeability studies based on Explorer 35/ALSEP regressions, wherein inferences are drawn from regression line slopes differing from unity by the order of one percent, is called into question. We emphasize the need to critically address the question of small deviations in magnetometer sensitivity factors from nominal values as a part of any two-magnetometer lunar permeability study.

  17. Magnetic permeability measurements and a lunar core

    NASA Technical Reports Server (NTRS)

    Goldstein, B. E.; Phillips, R. J.; Russell, C. T.

    1976-01-01

    Measurements of the magnetic field induced in the moon while it is in the geomagnetic tail lobes have been interpreted in terms of lunar magnetic permeability due to free iron content; such studies ignored the possibility that a highly conducting lunar core (Fe or FeS) would exclude magnetic fields with an apparent diamagnetic effect. Using lunar chemical and thermal models to determine plausible limits of magnetic permeability, we interpret measurements of the induced moment. The maximum likely radius of a lunar core is 580 km. Subsatellite and ALSEP measurements of the induced field are in disagreement. Resolving the differences is critical to determining whether a core could or does exist.

  18. Predicting the permeability of sediments entering subduction zones

    NASA Astrophysics Data System (ADS)

    Daigle, Hugh; Screaton, Elizabeth J.

    2015-07-01

    Using end-member permeabilities defined by a worldwide compilation of sediment permeabilities at convergent margins, we compare permeability predictions using a geometric mean and a two-component effective medium theory (EMT). Our implementation of EMT includes a threshold fraction of the high-permeability component that determines whether flow occurs dominantly in the high- or low-permeability component. We find that this threshold fraction in most cases is equal to the silt + sand-sized fraction of the sediment. This suggests that sediments undergoing primary consolidation tend to exhibit flow equally distributed between the high- and low-permeability components. We show that the EMT method predicts permeability better than the weighted geometric mean of the end-member values for clay fractions <0.6. This work provides insight into the microstructural controls on permeability in subducting sediments and valuable guidance for locations which lack site-specific permeability results but have available grain-size information.

  19. Vascular Permeability and Drug Delivery in Cancers

    PubMed Central

    Azzi, Sandy; Hebda, Jagoda K.; Gavard, Julie

    2013-01-01

    The endothelial barrier strictly maintains vascular and tissue homeostasis, and therefore modulates many physiological processes such as angiogenesis, immune responses, and dynamic exchanges throughout organs. Consequently, alteration of this finely tuned function may have devastating consequences for the organism. This is particularly obvious in cancers, where a disorganized and leaky blood vessel network irrigates solid tumors. In this context, vascular permeability drives tumor-induced angiogenesis, blood flow disturbances, inflammatory cell infiltration, and tumor cell extravasation. This can directly restrain the efficacy of conventional therapies by limiting intravenous drug delivery. Indeed, for more effective anti-angiogenic therapies, it is now accepted that not only should excessive angiogenesis be alleviated, but also that the tumor vasculature needs to be normalized. Recovery of normal state vasculature requires diminishing hyperpermeability, increasing pericyte coverage, and restoring the basement membrane, to subsequently reduce hypoxia, and interstitial fluid pressure. In this review, we will introduce how vascular permeability accompanies tumor progression and, as a collateral damage, impacts on efficient drug delivery. The molecular mechanisms involved in tumor-driven vascular permeability will next be detailed, with a particular focus on the main factors produced by tumor cells, especially the emblematic vascular endothelial growth factor. Finally, new perspectives in cancer therapy will be presented, centered on the use of anti-permeability factors and normalization agents. PMID:23967403

  20. A microdevice for parallelized pulmonary permeability studies.

    PubMed

    Bol, Ludivine; Galas, Jean-Christophe; Hillaireau, Hervé; Le Potier, Isabelle; Nicolas, Valérie; Haghiri-Gosnet, Anne-Marie; Fattal, Elias; Taverna, Myriam

    2014-04-01

    We describe a compartmentalized microdevice specifically designed to perform permeability studies across a model of lung barrier. Epithelial cell barriers were reproduced by culturing Calu-3 cells at the air-liquid interface (AIC) in 1 mm² microwells made from a perforated glass slide with an embedded porous membrane. We created a single basolateral reservoir for all microwells which eliminated the need to renew the growth medium during the culture growth phase. To perform drug permeability studies on confluent cell layers, the cell culture slide was aligned and joined to a collection platform consisting in 35 μL collection reservoirs connected at the top and bottom with microchannels. The integrity and functionality of the cell barriers were demonstrated by measurement of trans-epithelial electrical resistance (TEER), confocal imaging and permeability assays of ¹⁴C-sucrose. Micro-cell barriers were able to form confluent layers in 1 week, demonstrating a similar bioelectrical evolution as the Transwell systems used as controls. Tight junctions were observed throughout the cell-cell interfaces, and the low permeability coefficients of ¹⁴C-sucrose confirmed their functional presence, creating a primary barrier to the diffusion of solutes. This microdevice could facilitate the monitoring of biomolecule transport and the screening of formulations promoting their passage across the pulmonary barrier, in order to select candidates for pulmonary administration to patients. PMID:24337430

  1. EVALUATION OF PERMEABLE REACTIVE BARRIER PERFORMANCE

    EPA Science Inventory

    The permeable reactive barrier (PRB) technology represents a passive option for long-term treatment of ground-water contamination. PRBs are a potentially more cost-effective treatment option for a variety of dissolved contaminants, such as certain types of chlorinated solvents, ...

  2. A permeable rotating-wheel solvent extractor

    NASA Technical Reports Server (NTRS)

    Kahn, D. R.; Nady, L. A.

    1972-01-01

    Column-type device reported employs circular permeable structures of wire mesh screen for extracting solvents from systems with low density differences and low interfacial tensions. Rotating screen wheels of structure fasten to shaft; stationary screen structures are supported by circular bands connected by radial metal arms.

  3. Permeable pavement research – Edison, New Jersey

    EPA Science Inventory

    These are the slides for the New York City Concrete Promotional Council Pervious Concrete Seminar presentation. The basis for the project, the monitoring design and some preliminary monitoring data from the permeable pavement parking lot at the Edison Environmental Center are pre...

  4. Tailoring wall permeabilities for enhanced filtration

    NASA Astrophysics Data System (ADS)

    Herterich, J. G.; Vella, D.; Field, R. W.; Hankins, N. P.; Griffiths, I. M.

    2015-05-01

    The build-up of contaminants at the wall of cross-flow membrane filtration systems can be detrimental to the operation of such systems because of, amongst other things, the osmotic backflow it may induce. In this paper, we propose a strategy to avoid the negative effects of backflow due to osmosis by using 2D channels bounded by walls with a combination of permeable and impermeable segments. We show that preventing flow through the final portion of the channel can increase the efficiency of filtration and we determine the optimal fraction occupied by the permeable wall that maximizes efficiency. Our analysis uses a combination of numerical techniques and asymptotic analysis in the limit of low wall permeabilities. Finally, we consider how the energy cost of filtration depends on the Péclet number and show that the energy cost per unit of filtered water may be minimized by appropriately choosing both the Péclet number and the permeable-region fraction.

  5. Estimating Plastic Film Permeability Under Field Conditions

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Fumigant emission is an important air quality and human health concern. Plastic films are used to reduce emissions. Laboratory tests have shown large differences in permeability between various films, including the typical polyethylene films (PEs), virtually impermeable films (VIFs), and semi-impe...

  6. Pump and treat in low permeability media

    SciTech Connect

    Mackay, D.M.

    1996-08-01

    Pump and Treat (P&T) is a commonly applied technology whose primary promise for the low permeability environments of interest to these technology reviews is almost certainly containment of the problem. Conventional P&T would be expected to offer little promise of complete restoration in such environments, unless very long time frames (decades or centuries) are considered. A variety of approaches have been proposed to enhance the efficiency of P&T; some appear to offer little promise in low or mixed permeability environments, while others may offer more promise (e.g. hydro- or pneumatic-fracturing, which are described elsewhere in this document, and application of vacuum to the extraction well(s), which is a proprietary technology whose promise is currently difficult to assess objectively). Understanding the potential advantages and means of optimizing these enhancement approaches requires more understanding of the basic processes limiting P&T performance in low or mixed permeability media. These efforts are probably also necessary to understand the advantages and means of optimizing many of the very different remedial technologies that may be applicable to low or mixed permeability environments. Finally, since a reasonably certain capability of P&T is containment (i.e. prevention of further migration of contaminants), P&T may generally be required as a sort of safety net around sites at which the alternative technologies are being tested or applied. 23 refs.

  7. SINGLE-INTERVAL GAS PERMEABILITY ESTIMATION

    EPA Science Inventory

    Single-interval, steady-steady-state gas permeability testing requires estimation of pressure at a screened interval which in turn requires measurement of friction factors as a function of mass flow rate. Friction factors can be obtained by injecting air through a length of pipe...

  8. Reduced hydrogen permeability at high temperatures

    NASA Technical Reports Server (NTRS)

    Stephens, J. R.; Klopp, W. D.; Misencik, J. A.

    1981-01-01

    CO and CO2 reduce hydrogen loss through iron, nickel, and cobalt based alloy tubes. Method is based on concept that oxide film on metal surface reduces hydrogen permeability through metal; adding CO or CO2 forms oxide films continuously during operation, and hydrogen containment is improved. Innovation enhances prospects for Stirling engine system utilization.

  9. Permeability Measurements in Carbon-Epoxy Composites

    NASA Technical Reports Server (NTRS)

    Zdenek, Michael J.

    1999-01-01

    To determine the permeability of the composite feedline, that is proposed to be used in the X-33 Reusable Launch Vehicle (RLV), three 8 x 8-in. coupons were constructed. Two of the coupons were layed-up with 4 plies of plain weave prepreg [0/90, plus or minus 45, plus or minus 45, 0/90] and the other one layed-up with 4 plies of unidirectional prepreg [0, 90, 90, 0]. The coupons were vacuumed bagged and cured to manufactures specifications. The coupons were then placed in an apparatus to test for permeability. Nitrogen gas was used to permeate through the coupons at a pressure of 5 psig. A manometer was placed on the opposite side of the coupons and was used to measure the height of the fluid with respect to time. From this data the mass flow rate of the gas could be calculated since the area of the manometer and the density of the gas is known. The results of the test are given. The permeability constant was calculated using Darcy's law, which related the pressure drop, flow rate of the permeating gas and resistance to flow through the coupon created. To put the results into prospective the permeability of sand stone and granite is 1E-15 and 1E-20 respectively.

  10. PRECISION AND RELIABILITY OF LABORATORY PERMEABILITY MEASUREMENTS

    EPA Science Inventory

    A limited set of laboratory test data on clay liner permeabilities was gathered from six sources to create a data bank suitable for a preliminary statistical analysis. The collected data were also used to survey the most commonly used permeameters and testing methods for clay lin...

  11. Permeability during densification of viscous droplets

    NASA Astrophysics Data System (ADS)

    Wadsworth, Fabian; Vasseur, Jérémie; Llewellin, Ed; Dobson, Katherine; Schauroth, Jenny; Heap, Michael; Farquharson, Jamie; Scheu, Bettina; Kendrick, Jackie; Lavallée, Yan; von Aulock, Felix; Dingwell, Donald B.

    2016-04-01

    Fragmentation of magma can yield a transiently granular material, which can subsequently weld back to a fluid-continuum. This process results in dramatic changes in the porosity of the material, which impacts its fluid permeability. We collate published data for the porosity and permeability of volcanic and synthetic materials which have undergone this process to different amounts. By discriminating data for which good microstructural information are provided, we use simple scaling arguments to collapse the data in both the still-granular, high porosity region, and the fluid-continuum low porosity region, such that a universal description can be provided. This allows us to describe the microstructural meaning of permeability scaling, and to infer the controls on the position of this transition between dominantly granular (dispersion) and dominantly fluid-continuum materials. Fractures in coherent magmas are thought to be a primary degassing pathway in high viscosity systems. As a specific application, we consider transiently granular magma being transported through and deposited in these fractures. We finally present a physical model for the kinetics of porosity changes in arrays of viscous droplets and compare this with our experimental data. The combination of the physical model for the evolution of porosity with the scaling between porosity and permeability permits us to describe the evolution of permeability during densification. We anticipate that this will be a useful tool for predicting the longevity of degassing pathways in granular filled cracks, both in conduits and shallow lava domes, as well as during the sedimentation of exceptionally hot ignimbrites undergoing compaction and welding.

  12. Connexin channel permeability to cytoplasmic molecules.

    PubMed

    Harris, Andrew L

    2007-01-01

    Connexin channels are known to be permeable to a variety of cytoplasmic molecules. The first observation of second messenger junctional permeability, made approximately 30 years ago, sparked broad interest in gap junction channels as mediators of intercellular molecular signaling. Since then, much has been learned about the diversity of connexin channels with regard to isoform diversity, tissue and developmental distribution, modes of channel regulation, assembly, expression, biochemical modification and permeability, all of which appear to be dynamically regulated. This information has expanded the potential roles of connexin channels in development, physiology and disease, and made their elucidation much more complex--30 years ago such an orchestra of junctional dynamics was unanticipated. Only recently, however, have investigators been able to directly address, in this more complex framework, the key issue: what specific biological molecules, second messengers and others, are able to permeate the various types of connexin channels, and how well? An important related issue, given the ever-growing list of connexin-related pathologies, is how these permeabilities are altered by disease-causing connexin mutations. Together, many studies show that a variety of cytoplasmic molecules can permeate the different types of connexin channels. A few studies reveal differences in permeation by different molecules through a particular type of connexin channel, and differences in permeation by a particular molecule through different types of connexin channels. This article describes and evaluates the various methods used to obtain these data, presents an annotated compilation of the results, and discusses the findings in the context of what can be inferred about mechanism of selectivity and potential relevance to signaling. The data strongly suggest that highly specific interactions take place between connexin pores and specific biological molecular permeants, and that those

  13. A new quasi-steady method to measure gas permeability of weakly permeable porous media

    NASA Astrophysics Data System (ADS)

    Jannot, Yves; Lasseux, Didier

    2012-01-01

    A new quasi-steady method for the determination of the apparent gas permeability of porous materials is presented in this paper along with the corresponding interpretative physical model derived from the unsteady flow equations. This method is mainly dedicated to the measurement of very low permeability of thin porous media, although thicker but more permeable samples may also be analyzed. The method relies on quasi-steady flow resulting from a (quasi) constant pressure maintained at the inlet face of the sample. Gas flow-rate, as low as 3 × 10-10 m3/s, is determined from the record of pressure increase in a reservoir connected to the outlet face of the sample. An estimate of the characteristic time, tc, to reach quasi-steady flow after imposing a constant pressure at the inlet is derived. It is validated by direct numerical simulations of the complete unsteady flow, clearly defining the required experimental duration for the method to apply. Experimental results obtained on rather permeable and thick rock samples are reported showing an excellent agreement of the measured permeability with that determined independently on the same sample whereas the experimental value of tc is also in very good agreement with the predicted one. The method is further employed on a composite material sheet allowing the identification of an apparent gas permeability of about 10-23 m2.

  14. Moisture Durability of Vapor Permeable Insulating Sheathing (Fact Sheet)

    SciTech Connect

    Not Available

    2013-10-01

    In this project, Building America team Building Science Corporation researched some of the ramifications of using exterior, vapor permeable insulation on retrofit walls with vapor permeable cavity insulation. Retrofit strategies are a key factor in reducing exterior building stock consumption.

  15. Neutrophils, nitric oxide, and microvascular permeability in severe sepsis

    Technology Transfer Automated Retrieval System (TEKTRAN)

    STUDY OBJECTIVES: Alterations in microvascular permeability are prevalent in patients with sepsis; a recent study reported that patients with septic shock had increased capillary filtration coefficient (Kf), a noninvasive index of microvascular permeability. We aimed to determine whether patients wi...

  16. Permeability-porosity relationships in sedimentary rocks

    USGS Publications Warehouse

    Nelson, Philip H.

    1994-01-01

    In many consolidated sandstone and carbonate formations, plots of core data show that the logarithm of permeability (k) is often linearly proportional to porosity (??). The slope, intercept, and degree of scatter of these log(k)-?? trends vary from formation to formation, and these variations are attributed to differences in initial grain size and sorting, diagenetic history, and compaction history. In unconsolidated sands, better sorting systematically increases both permeability and porosity. In sands and sandstones, an increase in gravel and coarse grain size content causes k to increase even while decreasing ??. Diagenetic minerals in the pore space of sandstones, such as cement and some clay types, tend to decrease log(k) proportionately as ?? decreases. Models to predict permeability from porosity and other measurable rock parameters fall into three classes based on either grain, surface area, or pore dimension considerations. (Models that directly incorporate well log measurements but have no particular theoretical underpinnings from a fourth class.) Grain-based models show permeability proportional to the square of grain size times porosity raised to (roughly) the fifth power, with grain sorting as an additional parameter. Surface-area models show permeability proportional to the inverse square of pore surface area times porosity raised to (roughly) the fourth power; measures of surface area include irreducible water saturation and nuclear magnetic resonance. Pore-dimension models show permeability proportional to the square of a pore dimension times porosity raised to a power of (roughly) two and produce curves of constant pore size that transgress the linear data trends on a log(k)-?? plot. The pore dimension is obtained from mercury injection measurements and is interpreted as the pore opening size of some interconnected fraction of the pore system. The linear log(k)-?? data trends cut the curves of constant pore size from the pore-dimension models

  17. Permeability Changes in Reaction Induced Fracturing

    NASA Astrophysics Data System (ADS)

    Ulven, Ole Ivar; Malthe-Sørenssen, Anders; Kalia, Rajiv

    2013-04-01

    The process of fracture formation due to a volume increasing chemical reaction has been studied in a variety of different settings, e.g. weathering of dolerites by Røyne et al.[4], serpentinization and carbonation of peridotite by Rudge et al.[3] and replacement reactions in silica-poor igneous rocks by Jamtveit et al.[1]. It is generally assumed that fracture formation will increase the net permeability of the rock, and thus increase the reactant transport rate and subsequently the total reaction rate, as summarised by Kelemen et al.[2]. Røyne et al.[4] have shown that transport in fractures will have an effect on the fracture pattern formed. Understanding the feedback process between fracture formation and permeability changes is essential in assessing industrial scale CO2 sequestration in ultramafic rock, but little is seemingly known about how large the permeability change will be in reaction-induced fracturing under compression, and it remains an open question how sensitive a fracture pattern is to permeability changes. In this work, we study the permeability of fractures formed under compression, and we use a 2D discrete element model to study the fracture patterns and total reaction rates achieved with different permeabilities. We achieve an improved understanding of the feedback processes in reaction-driven fracturing, thus improving our ability to decide whether industrial scale CO2 sequestration in ultramafic rock is a viable option for long-term handling of CO2. References [1] Jamtveit, B, Putnis, C. V., and Malthe-Sørenssen, A., "Reaction induced fracturing during replacement processes," Contrib. Mineral Petrol. 157, 2009, pp. 127 - 133. [2] Kelemen, P., Matter, J., Streit, E. E., Rudge, J. F., Curry, W. B., and Blusztajn, J., "Rates and Mechanisms of Mineral Carbonation in Peridotite: Natural Processes and Recipes for Enhanced, in situ CO2 Capture and Storage," Annu. Rev. Earth Planet. Sci. 2011. 39:545-76. [3] Rudge, J. F., Kelemen, P. B., and

  18. Nam Con Son Basin

    SciTech Connect

    Tin, N.T.; Ty, N.D.; Hung, L.T.

    1994-07-01

    The Nam Con Son basin is the largest oil and gas bearing basin in Vietnam, and has a number of producing fields. The history of studies in the basin can be divided into four periods: Pre-1975, 1976-1980, 1981-1989, and 1990-present. A number of oil companies have carried out geological and geophysical studies and conducted drilling activities in the basin. These include ONGC, Enterprise Oil, BP, Shell, Petro-Canada, IPL, Lasmo, etc. Pre-Tertiary formations comprise quartz diorites, granodiorites, and metamorphic rocks of Mesozoic age. Cenozoic rocks include those of the Cau Formation (Oligocene and older), Dua Formation (lower Miocene), Thong-Mang Cau Formation (middle Miocene), Nam Con Son Formation (upper Miocene) and Bien Dong Formation (Pliocene-Quaternary). The basement is composed of pre-Cenozoic formations. Three fault systems are evident in the basin: north-south fault system, northeast-southwest fault system, and east-west fault system. Four tectonic zones can also be distinguished: western differentiated zone, northern differentiated zone, Dua-Natuna high zone, and eastern trough zone.

  19. Exploring the scale-dependent permeability of fractured andesite

    NASA Astrophysics Data System (ADS)

    Heap, Michael J.; Kennedy, Ben M.

    2016-08-01

    Extension fractures in volcanic systems exist on all scales, from microscopic fractures to large fissures. They play a fundamental role in the movement of fluids and distribution of pore pressure, and therefore exert considerable influence over volcanic eruption recurrence. We present here laboratory permeability measurements for porous (porosity = 0.03-0.6) andesites before (i.e., intact) and after failure in tension (i.e., the samples host a throughgoing tensile fracture). The permeability of the intact andesites increases with increasing porosity, from 2 ×10-17 to 5 ×10-11 m2. Following fracture formation, the permeability of the samples (the equivalent permeability) falls within a narrow range, 2- 6 ×10-11 m2, regardless of their initial porosity. However, laboratory measurements on fractured samples likely overestimate the equivalent permeability due to the inherent scale-dependence of permeability. To explore this scale-dependence, we first determined the permeability of the tensile fractures using a two-dimensional model that considers flow in parallel layers. Our calculations highlight that tensile fractures in low-porosity samples are more permeable (as high as 3.5 ×10-9 m2) than those in high-porosity samples (as low as 4.1 ×10-10 m2), a difference that can be explained by an increase in fracture tortuosity with porosity. We then use our fracture permeability data to model the equivalent permeability of fractured rock (with different host rock permeabilities, from 10-17 to 10-11 m2) with increasing lengthscale. We highlight that our modelling approach can be used to estimate the equivalent permeability of numerous scenarios at andesitic stratovolcanoes in which the fracture density and width and host rock porosity or permeability are known. The model shows that the equivalent permeability of fractured andesite depends heavily on the initial host rock permeability and the scale of interest. At a given lengthscale, the equivalent permeability of high-permeability

  20. Studying the Variation in Gas Permeability of Porous Building Substrates

    NASA Astrophysics Data System (ADS)

    Townsend, L.; Savidge, C. R.; Hu, L.; Rizzo, D. M.; Hayden, N. J.; Dewoolkar, M.

    2009-12-01

    Understanding permeability of building materials is important for problems involving studies of contaminant transport. Examples include contamination from fire, acid rain, and chemical and biological weapons. Our research investigates the gas permeability of porous building substrates such as concretes, limestones, sandstones, and bricks. Each sample was cored to produce 70 mm (2.75”) diameter cores approximately 75-130 mm (3-5”) tall. The surface gas permeability was measured on the top surface of these specimens using the AutoScan II device manufactured by New England Research, Inc. The measurements were taken along a 3 mm grid producing a map of surface gas permeability. An example map is shown in Figure 1. The macroscopic measurements were performed along the entire cored specimen. A second set of measurements were made on a 5 mm thick slice cut from the top of each specimen to examine whether these measurements compare better with the surface measurements. The macroscopic gas permeability was measured for all specimens using ASTM D 4525. The results are summarized in Table 1. In general, the surface and macroscopic gas permeability measurements (Table 1) compare reasonably well (within one order of magnitude). The permeability of the 5 mm slices is not significantly different from the entire core for the specimens tested. Figure 1. Results of surface permeability mappingof Ohio Sandstone using the AutoScan II device. a) Map of gas permeability b) Range of gas permeability c) Density function of permeability. Table 1. Gas permeability values (mD)

  1. 46 CFR 172.240 - Permeability of spaces.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 46 Shipping 7 2010-10-01 2010-10-01 false Permeability of spaces. 172.240 Section 172.240 Shipping... Permeability of spaces. When doing the calculations required in § 172.225, (a) The permeability of a floodable space, other than a machinery or cargo space, must be assumed as listed in Table 172.240;...

  2. 46 CFR 172.140 - Permeability of spaces.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 46 Shipping 7 2010-10-01 2010-10-01 false Permeability of spaces. 172.140 Section 172.140 Shipping... Subchapter O of This Chapter § 172.140 Permeability of spaces. (a) When doing the calculations required in § 172.130, the permeability of a floodable space other than a machinery space must be as listed in...

  3. 46 CFR 174.090 - Permeability of spaces.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 46 Shipping 7 2010-10-01 2010-10-01 false Permeability of spaces. 174.090 Section 174.090 Shipping... Permeability of spaces. When doing the calculations required in § 174.065— (a) The permeability of a floodable space, other than a machinery space, must be as listed in Table 174.090; and (b) Calculations in which...

  4. 46 CFR 172.185 - Permeability of spaces.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 46 Shipping 7 2010-10-01 2010-10-01 false Permeability of spaces. 172.185 Section 172.185 Shipping... Under Subchapter O of This Chapter § 172.185 Permeability of spaces. (a) When doing the calculations required in § 172.170, the permeability of a floodable space other than a machinery space must be as...

  5. 46 CFR 172.140 - Permeability of spaces.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 46 Shipping 7 2012-10-01 2012-10-01 false Permeability of spaces. 172.140 Section 172.140 Shipping... Subchapter O of This Chapter § 172.140 Permeability of spaces. (a) When doing the calculations required in § 172.130, the permeability of a floodable space other than a machinery space must be as listed in...

  6. 46 CFR 172.185 - Permeability of spaces.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 46 Shipping 7 2014-10-01 2014-10-01 false Permeability of spaces. 172.185 Section 172.185 Shipping... Under Subchapter O of This Chapter § 172.185 Permeability of spaces. (a) When doing the calculations required in § 172.170, the permeability of a floodable space other than a machinery space must be as...

  7. 46 CFR 172.185 - Permeability of spaces.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 46 Shipping 7 2013-10-01 2013-10-01 false Permeability of spaces. 172.185 Section 172.185 Shipping... Under Subchapter O of This Chapter § 172.185 Permeability of spaces. (a) When doing the calculations required in § 172.170, the permeability of a floodable space other than a machinery space must be as...

  8. 46 CFR 174.090 - Permeability of spaces.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 46 Shipping 7 2012-10-01 2012-10-01 false Permeability of spaces. 174.090 Section 174.090 Shipping... Permeability of spaces. When doing the calculations required in § 174.065— (a) The permeability of a floodable space, other than a machinery space, must be as listed in Table 174.090; and (b) Calculations in which...

  9. 46 CFR 172.140 - Permeability of spaces.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 46 Shipping 7 2014-10-01 2014-10-01 false Permeability of spaces. 172.140 Section 172.140 Shipping... Subchapter O of This Chapter § 172.140 Permeability of spaces. (a) When doing the calculations required in § 172.130, the permeability of a floodable space other than a machinery space must be as listed in...

  10. 46 CFR 172.185 - Permeability of spaces.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 46 Shipping 7 2012-10-01 2012-10-01 false Permeability of spaces. 172.185 Section 172.185 Shipping... Under Subchapter O of This Chapter § 172.185 Permeability of spaces. (a) When doing the calculations required in § 172.170, the permeability of a floodable space other than a machinery space must be as...

  11. 46 CFR 172.240 - Permeability of spaces.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 46 Shipping 7 2014-10-01 2014-10-01 false Permeability of spaces. 172.240 Section 172.240 Shipping... Permeability of spaces. When doing the calculations required in § 172.225, (a) The permeability of a floodable space, other than a machinery or cargo space, must be assumed as listed in Table 172.240;...

  12. 46 CFR 172.240 - Permeability of spaces.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 46 Shipping 7 2013-10-01 2013-10-01 false Permeability of spaces. 172.240 Section 172.240 Shipping... Permeability of spaces. When doing the calculations required in § 172.225, (a) The permeability of a floodable space, other than a machinery or cargo space, must be assumed as listed in Table 172.240;...

  13. 46 CFR 174.090 - Permeability of spaces.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 46 Shipping 7 2014-10-01 2014-10-01 false Permeability of spaces. 174.090 Section 174.090 Shipping... Permeability of spaces. When doing the calculations required in § 174.065— (a) The permeability of a floodable space, other than a machinery space, must be as listed in Table 174.090; and (b) Calculations in which...

  14. 46 CFR 174.090 - Permeability of spaces.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 46 Shipping 7 2013-10-01 2013-10-01 false Permeability of spaces. 174.090 Section 174.090 Shipping... Permeability of spaces. When doing the calculations required in § 174.065— (a) The permeability of a floodable space, other than a machinery space, must be as listed in Table 174.090; and (b) Calculations in which...

  15. 46 CFR 172.240 - Permeability of spaces.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 46 Shipping 7 2012-10-01 2012-10-01 false Permeability of spaces. 172.240 Section 172.240 Shipping... Permeability of spaces. When doing the calculations required in § 172.225, (a) The permeability of a floodable space, other than a machinery or cargo space, must be assumed as listed in Table 172.240;...

  16. 46 CFR 172.140 - Permeability of spaces.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 46 Shipping 7 2013-10-01 2013-10-01 false Permeability of spaces. 172.140 Section 172.140 Shipping... Subchapter O of This Chapter § 172.140 Permeability of spaces. (a) When doing the calculations required in § 172.130, the permeability of a floodable space other than a machinery space must be as listed in...

  17. 46 CFR 172.185 - Permeability of spaces.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 46 Shipping 7 2011-10-01 2011-10-01 false Permeability of spaces. 172.185 Section 172.185 Shipping... Under Subchapter O of This Chapter § 172.185 Permeability of spaces. (a) When doing the calculations required in § 172.170, the permeability of a floodable space other than a machinery space must be as...

  18. 46 CFR 172.140 - Permeability of spaces.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 46 Shipping 7 2011-10-01 2011-10-01 false Permeability of spaces. 172.140 Section 172.140 Shipping... Subchapter O of This Chapter § 172.140 Permeability of spaces. (a) When doing the calculations required in § 172.130, the permeability of a floodable space other than a machinery space must be as listed in...

  19. 46 CFR 174.090 - Permeability of spaces.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 46 Shipping 7 2011-10-01 2011-10-01 false Permeability of spaces. 174.090 Section 174.090 Shipping... Permeability of spaces. When doing the calculations required in § 174.065— (a) The permeability of a floodable space, other than a machinery space, must be as listed in Table 174.090; and (b) Calculations in which...

  20. 46 CFR 172.240 - Permeability of spaces.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 46 Shipping 7 2011-10-01 2011-10-01 false Permeability of spaces. 172.240 Section 172.240 Shipping... Permeability of spaces. When doing the calculations required in § 172.225, (a) The permeability of a floodable space, other than a machinery or cargo space, must be assumed as listed in Table 172.240;...

  1. Control of vascular permeability by adhesion molecules.

    PubMed

    Sarelius, Ingrid H; Glading, Angela J

    2015-01-01

    Vascular permeability is a vital function of the circulatory system that is regulated in large part by the limited flux of solutes, water, and cells through the endothelial cell layer. One major pathway through this barrier is via the inter-endothelial junction, which is driven by the regulation of cadherin-based adhesions. The endothelium also forms attachments with surrounding proteins and cells via 2 classes of adhesion molecules, the integrins and IgCAMs. Integrins and IgCAMs propagate activation of multiple downstream signals that potentially impact cadherin adhesion. Here we discuss the known contributions of integrin and IgCAM signaling to the regulation of cadherin adhesion stability, endothelial barrier function, and vascular permeability. Emphasis is placed on known and prospective crosstalk signaling mechanisms between integrins, the IgCAMs- ICAM-1 and PECAM-1, and inter-endothelial cadherin adhesions, as potential strategic signaling nodes for multipartite regulation of cadherin adhesion. PMID:25838987

  2. Electrostatically gated membrane permeability in inorganic protocells

    NASA Astrophysics Data System (ADS)

    Li, Mei; Harbron, Rachel L.; Weaver, Jonathan V. M.; Binks, Bernard P.; Mann, Stephen

    2013-06-01

    Although several strategies are now available to produce functional microcompartments analogous to primitive cell-like structures, little progress has been made in generating protocell constructs with self-controlled membrane permeability. Here we describe the preparation of water-dispersible colloidosomes based on silica nanoparticles and delineated by a continuous semipermeable inorganic membrane capable of self-activated, electrostatically gated permeability. We use crosslinking and covalent grafting of a pH-responsive copolymer to generate an ultrathin elastic membrane that exhibits selective release and uptake of small molecules. This behaviour, which depends on the charge of the copolymer coronal layer, serves to trigger enzymatic dephosphorylation reactions specifically within the protocell aqueous interior. This system represents a step towards the design and construction of alternative types of artificial chemical cells and protocell models based on spontaneous processes of inorganic self-organization.

  3. Electrostatically gated membrane permeability in inorganic protocells.

    PubMed

    Li, Mei; Harbron, Rachel L; Weaver, Jonathan V M; Binks, Bernard P; Mann, Stephen

    2013-06-01

    Although several strategies are now available to produce functional microcompartments analogous to primitive cell-like structures, little progress has been made in generating protocell constructs with self-controlled membrane permeability. Here we describe the preparation of water-dispersible colloidosomes based on silica nanoparticles and delineated by a continuous semipermeable inorganic membrane capable of self-activated, electrostatically gated permeability. We use crosslinking and covalent grafting of a pH-responsive copolymer to generate an ultrathin elastic membrane that exhibits selective release and uptake of small molecules. This behaviour, which depends on the charge of the copolymer coronal layer, serves to trigger enzymatic dephosphorylation reactions specifically within the protocell aqueous interior. This system represents a step towards the design and construction of alternative types of artificial chemical cells and protocell models based on spontaneous processes of inorganic self-organization. PMID:23695636

  4. Permeability of cork for water and ethanol.

    PubMed

    Fonseca, Ana Luisa; Brazinha, Carla; Pereira, Helena; Crespo, Joao G; Teodoro, Orlando M N D

    2013-10-01

    Transport properties of natural (noncompressed) cork were evaluated for water and ethanol in both vapor and liquid phases. The permeability for these permeants has been measured, as well as the sorption and diffusion coefficients. This paper focuses on the differences between the transport of gases' relevant vapors and their liquids (water and ethanol) through cork. A transport mechanism of vapors and liquids is proposed. Experimental evidence shows that both vapors and liquids permeate not only through the small channels across the cells (plasmodesmata), as in the permeation of gases, but also through the walls of cork cells by sorption and diffusion as in dense membranes. The present study also shows that cork permeability for gases was irreversibly and drastically decreased after cork samples were exposed to ethanol or water in liquid phase. PMID:24001097

  5. Selective gel system for permeability profile control

    SciTech Connect

    Shu, P.

    1990-02-27

    This patent describes a process for closing pores in a more permeable zone of a formation. It comprises: placing into an aqueous solution a first composition sufficient to form ex-situ a size selective, shear thinning first gel which comprises a xanthan biopolymer, and a transitional metal ion; placing into the aqueous solution a second composition sufficient to form thermally a second in-situ gel which is substantially more resistant to formation conditions than the first gel. The composition comprises an aldehyde, and a phenolic compound; allowing the aqueous solution sufficient time to form the ex-situ gel; and injecting the aqueous solution containing the gel into the permeable zone where it reheals, is heated by the formation and thereafter forms a solid gel substantially more resistant to formation conditions than the first gel.

  6. Selective gel system for permeability profile control

    SciTech Connect

    Shu, P.

    1990-10-16

    This patent describes a selective gel for closing pores in a more permeable zone of a formation. It comprises: an aqueous solution of a first composition sufficient to form ex-situ a size selective, shear thinning first gel which comprises a xanthan biopolymer, and a transitional metal ion; and an aqueous solution of a second composition sufficient to form thermally a second in-situ gel that which comprises and aldehyde, and a phenolic compound which solutions are combined and allowed to form a shearable, rehealable ex-situ gel which can be injected into the permeable zone where it reheals when heated by the formation and thereafter forms a solid gel substantially more resistant to formation conditions than the first gel.

  7. Monitoring pulmonary vascular permeability using radiolabeled transferrin

    SciTech Connect

    Basran, G.S.; Hardy, J.G.

    1988-07-01

    A simple, noninvasive technique for monitoring pulmonary vascular permeability in patients in critical care units is discussed. High vascular permeability is observed in patients with clinically defined adult respiratory distress syndrome (ARDS) but not in patients with hydrostatic pulmonary edema or in patients with minor pulmonary insults who are considered to be at risk of developing ARDS. The technique has been used in the field of therapeutics and pharmacology to test the effects of the putative antipermeability agents methylprednisolone and terbutaline sulfate. There appears to be a good correlation between the acute inhibitory effect of either drug on transferrin exudation and patient prognosis. Thus, a byproduct of such drug studies may be an index of survival in patients with established ARDS.

  8. Nonlinear effective pressure law for permeability

    NASA Astrophysics Data System (ADS)

    Li, M.; Xiao, W.-L.; Bernabé, Y.; Zhao, J.-Z.

    2014-01-01

    The permeability k of porous rocks is known to vary with confining pressure pc and pore fluid pressure pf. But it is, in principle, possible to replace the two-variable function k(pf, pc) by a function k(peff) of a single variable, peff(pf, pc), called the effective pressure. Our goal in this paper is to establish an experimental method for determining a possibly nonlinear, effective pressure law (EPL) for permeability, i.e., find the function κs(pf, pc) such that the effective pressure is given by peff = pc - κs(pf, pc) pf. We applied this method to a set of 26 sandstone cores from various hydrocarbon reservoirs in China. We found that κs greatly varied, from sample to sample, in magnitude and range, sometimes even reaching theoretically prohibited values (i.e., greater than 1 or lower than porosity). One interesting feature of κs(pf, pc) is that it could be approximately described in all rocks but one as a decreasing function κs(pc - pf) of Terzaghi's differential pressure. We also investigated the dependence of permeability on peff for each of our samples. Three models from the literature, i.e., exponential (E), power law (P), and the Walsh model (W), were tested. The (W) model was more likely to fit the experimental data of cores with a high pressure dependence of permeability whereas (E) occurred more frequently in low-pressure-sensitive rocks. Finally, we made various types of two- and three-dimensional microstructural observations that generally supported the trend mentioned above.

  9. Methods of determining permeability, transmissibility and drawdown

    USGS Publications Warehouse

    Bentall, Ray

    1964-01-01

    If the Theis graphical method is used for determining the hydraulic constants of an aquifer under water-table conditions, the observed drawdowns should be corrected for the decrease in saturated thickness. This is especially true if the drawdown is a large fraction of the original saturated thickness, for then the computed coefficient of permeability is highly inaccurate if based on observed, rather than corrected, water levels. Wenzel's limiting formula, a modification of the Theis graphical method, is useful where u=r2s/4Tt is less than about 0.01. However, a shorter procedure for determination of the coefficient of transmissibility, as well as the coefficient of storage, consists of plotting the values of the corrected drawdowns against the values of the logarithm of r. Wenzel (1942) suggested that observation wells be situated on lines that extend upgradient and downgradient from the pumped well. However, a detailed analysis of aquifer-test results indicates that such a restriction is unnecessary. The gradient method for determining permeability should yield the same results as the Thies method. The former, when applied for a distance within the range of applicability of the latter, is merely a duplication of effort or, at best, a crude check. Because of the limitations of accuracy in plotting, the gradient method is much less satisfactory. That Wenzel (1942) obtained identical results from the two methods is regarded as a coincidence. Failure to take into consideration the fact that the pumped well does not tap the full thickness of the aquifer leads to an apparent coefficient of permeability that is much too low, especially if the aquifer consists of stratified sediments. The average coefficient of permeability computed from uncorrected drawdowns may be only a little more than half of the true value.

  10. Effect of peptide conformation on membrane permeability.

    PubMed

    Boguslavsky, V; Hruby, V J; O'Brien, D F; Misicka, A; Lipkowski, A W

    2003-06-01

    The effect of peptide conformational constraint on the peptide permeation across the model membranes was examined by determining the permeability of pairs of cyclic and acyclic peptides related to c[d-Pen2, d-Pen5] enkephalin (DPDPE). The peptides were cyclized by formation of an intramolecular disulfide bridge between the second and fifth residues composed of either d-penicillamine or cysteine. In each case the acyclic peptide was three to seven times more permeable than corresponding cyclic peptide. The possibility that the differences in permeability of cyclic and acyclic peptides is based on the greater conformational freedom of the acyclic peptides in the presence of membrane was examined in more detail by isothermal titration calorimetric studies of Trp6-DPDPE and its acyclic analog. The membrane binding of the acyclic peptide is a more exothermic process than binding of its cyclic Trp6-DPDPE. The transfer of acyclic peptide from water to membrane is an enthalpy driven process, whereas the transfer of the cyclic peptide is driven by entropy. PMID:12753376

  11. Anisotropic Hydraulic Permeability Under Finite Deformation

    PubMed Central

    Ateshian, Gerard A.; Weiss, Jeffrey A.

    2011-01-01

    The structural organization of biological tissues and cells often produces anisotropic transport properties. These tissues may also undergo large deformations under normal function, potentially inducing further anisotropy. A general framework for formulating constitutive relations for anisotropic transport properties under finite deformation is lacking in the literature. This study presents an approach based on representation theorems for symmetric tensor-valued functions and provides conditions to enforce positive semi-definiteness of the permeability or diffusivity tensor. Formulations are presented which describe materials that are orthotropic, transversely isotropic, or isotropic in the reference state, and where large strains induce greater anisotropy. Strain-induced anisotropy of the permeability of a solid-fluid mixture is illustrated for finite torsion of a cylinder subjected to axial permeation. It is shown that, in general, torsion can produce a helical flow pattern, rather than the rectilinear pattern observed when adopting a more specialized, unconditionally isotropic spatial permeability tensor commonly used in biomechanics. The general formulation presented in this study can produce both affine and non-affine reorientation of the preferred directions of material symmetry with strain, depending on the choice of material functions. This study addresses a need in the biomechanics literature by providing guidelines and formulations for anisotropic strain-dependent transport properties in porous-deformable media undergoing large deformations. PMID:21034145

  12. Polymer nanocomposites: permeability, chain dynamics, mechanical properties

    NASA Astrophysics Data System (ADS)

    Sahu, Laxmi

    2005-03-01

    Polymer nanocomposites based on dispersion of surfactant treated expandable smectite clays such as montmorillonite layered silicates (MLS) have shown promise as organic-inorganic hybrids with the potential to improve barrier properties. Separately, flexible displays based on plastic substrates have reduced lifetimes tied to the low barrier properties. While there has been a general attribution of improved barrier properties to the tortuous path, this does not consider the influence the introduction of a secondary filler has on the morphology of the host polymer. Here we examine the influence of MLS nanoplatelets on the barrier properties and chain dynamics of polymers. We investigate the potential for host polymer modification by comparing two crystallizable polymers nylon and PET and resulting well dispersed nanocomposites. We study mechanical, cyclic fatigue and permeability of films. Permeability of the biaxially stretched film and when the film undergoes fatigue of 50 and 10000 cycles are also measured. Chain dynamics were modeled based on the Burger model fit to creep-recovery data. A systematic approach to predict the permeability considering amorphous, crystalline and MLS content and comparison with experimental values were done. We also conducted water absorption measurements to highlight the water absorption differences in the two polymers. Dimensional stability of PET was studied by measuring coefficient of thermal expansion of thin film on Si substrate by ellipsometry method.

  13. Patterns of permeability in eolian deposits

    SciTech Connect

    Goggin, D.J.; Chandler, M.A.; Kocurek, G.; Lake, L.W.

    1988-06-01

    The eolian, Jurassic Page sandstone of northeastern Arizona is marked by a highly ordered heterogeneity. The heterogeneity is expressed by the intricate association of stratification types, which are a direct result of the depositional processes. The dominant stratification types in eolian reservoirs are grainflow, grainfall, and wind-ripple deposits, which form on the lee faces of migrating dunes; interdune deposits, which form between migrating dunes; and extra-erg deposits, which occur sporadically when other depositional environments encroach upon an eolian system. These stratification types each have a unique permeability range, which implies that the fluid migration routes in eolian reservoirs will be dictated by the geometry and types of stratification present. One of the most important aspects of this study is the correlation of qualitative geologic descriptions with quantitative variables such as permeability. About 2,000 measurements were made with a field minipermeameter on an outcrop of the Page sandstone. These data show that three distinct permeability modes directly relate to the different stratification types.

  14. Gravity filtration of suspensions: permeability effects

    NASA Astrophysics Data System (ADS)

    Soori, Tejaswi; Wang, Mengyu; Ward, Thomas

    2015-11-01

    This paper examines the filtration rates of mono-modal suspensions as a function of time and a cake layer builds up through theory and experimentation. Darcy's Law, which describes fluid flow through porous media, was applied along with the Kynch theory of sedimentation, which provides the basis for analyzing low concentration (ϕ <=20%) cake formation. Experiments were performed to study the effects of varying particle sizes (45 μm <= d <= 1400 μm) and total solid concentration ϕ on both the formation rate of the cake layer and its flow permeability (k) in conjunction with the filter media. A CCD camera was used to capture images of the cake formation and fluid drainage processes, and subsequent image and theoretical analysis found the fluid flow experienced a constant pressure loss due to the permeability of the filter media, whereas the experienced pressure loss due to the cake formation varies as a function of time, ϕ and d. The rate of cake formation was also found to be independent of ϕ but dependent on d which can be attributed to a change in porosity affecting permeability. Studies on similar systems with multi-modal suspensions are in-progress.

  15. Atrial natriuretic factor increases vascular permeability

    SciTech Connect

    Lockette, W.; Brennaman, B. )

    1990-12-01

    An increase in central blood volume in microgravity may result in increased plasma levels of atrial natriuretic factor (ANF). Since elevations in plasma ANF are found in clinical syndromes associated with edema, and since space motion sickness induced by microgravity is associated with an increase in central blood volume and facial edema, we determined whether ANF increases capillary permeability to plasma protein. Conscious, bilaterally nephrectomized male rats were infused with either saline, ANF + saline, or hexamethonium + saline over 2 h following bolus injections of 125I-albumin and 14C-dextran of similar molecular size. Blood pressure was monitored and serial determinations of hematocrits were made. Animals infused with 1.0 micrograms.kg-1.min-1 ANF had significantly higher hematocrits than animals infused with saline vehicle. Infusion of ANF increased the extravasation of 125I-albumin, but not 14C-dextran from the intravascular compartment. ANF also induced a depressor response in rats, but the change in blood pressure did not account for changes in capillary permeability to albumin; similar depressor responses induced by hexamethonium were not accompanied by increased extravasation of albumin from the intravascular compartment. ANF may decrease plasma volume by increasing permeability to albumin, and this effect of ANF may account for some of the signs and symptoms of space motion sickness.

  16. Porosity and Permeability of Chondritic Materials

    NASA Technical Reports Server (NTRS)

    Zolensky, Michael E.; Corrigan, Catherine M.; Dahl, Jason; Long, Michael

    1996-01-01

    We have investigated the porosity of a large number of chondritic interplanetary dust particles and meteorites by three techniques: standard liquid/gas flow techniques, a new, non-invasive ultrasonic technique, and image processing of backscattered images . The latter technique is obviously best suited to sub-kg sized samples. We have also measured the gas and liquid permeabilities of some chondrites by two techniques: standard liquid/gas flow techniques, and a new, non-destructive pressure release technique. We find that chondritic IDP's have a somewhat bimodal porosity distribution. Peaks are present at 0 and 4% porosity; a tail then extends to 53%. These values suggest IDP bulk densities of 1.1 to 3.3 g/cc. Type 1-3 chondrite matrix porosities range up to 30%, with a peak at 2%. The bulk porosities for type 1-3 chondrites have the same approximate range as exhibited by matrix, indicating that other components of the bulk meteorites (including chondrules and aggregates) have the same average porosity as matrix. These results reveal that the porosity of primitive materials at scales ranging from nanogram to kilogram are similar, implying similar accretion dynamics operated through 12 orders of size magnitude. Permeabilities of the investigated chondrites vary by several orders of magnitude, and there appears to be no simple dependence of permeability with degree of aqueous alteration, or chondrite type.

  17. Atrial natriuretic factor increases vascular permeability

    NASA Technical Reports Server (NTRS)

    Lockette, Warren; Brennaman, Bruce

    1990-01-01

    An increase in central blood volume in microgravity may result in increased plasma levels of atrial natriuretic factor (ANF). In this study, it was determined whether ANF increases capillary permeability to plasma protein. Conscious, bilaterally nephrectomized male rats were infused with either saline, ANF + saline, or hexamethonium + saline over 2 h following bolus injections of (I-125)-albumin and (C-14)-dextran of similar molecular size. Blood pressure was monitored, and serial determinations of hematocrits were made. Animals infused with 1.0 microg/kg per min ANF had significantly higher hematocrits than animals infused with saline vehicle. Infusion of ANF increased the extravasation of (I-125)-albumin, but not (C-14)-dextran from the intravascular compartment. ANF also induced a depressor response in rats, but the change in blood pressure did not account for changes in capillary permeability to albumin; similar depressor responses induced by hexamethonium were not accompanied by increased extravasation of albumin from the intravascular compartment. ANF may decrease plasma volume by increasing permeability to albumin, and this effect of ANF may account for some of the signs and symptoms of space motion sickness.

  18. Effect of water on hydrogen permeability

    NASA Technical Reports Server (NTRS)

    Hulligan, David; Tomazic, William A.

    1987-01-01

    Doping of hydrogen with CO and CO2 was developed to reduce hydrogen permeation in Stirling engines by forming a low permeability oxide coating on the inner surface of the heater head tubes. Although doping worked well, under certain circumstances the protective oxide could be chemically reduced by the hydrogen in the engine. Some oxygen is required in the hydrogen to prevent reduction. Eventually, all the oxygen in the hydrogen gas - whatever its source - shows up as water. This is the result of hydrogen reducing the CO, CO2, or the protective inner surface oxides. This water can condense in the engine system under the right conditions. If the concentration of water vapor is reduced to a low enough level, the hydrogen can chemically reduce the oxide coating, resulting in an increase in permeability. This work was done to define the minimum water content required to avoid this reduction in the oxide coating. The results of this testing show that a minimum of approximately 750 ppm water is required to prevent an increase in permeability of CG-27, a high temperature metal alloy selected for Stirling engine heater tubes.

  19. Endothelial cell permeability to water and antipyrine

    SciTech Connect

    Garrick, R.A.

    1986-03-05

    The endothelium provides a structural barrier between plasma constituents and the tissues. The permeability characteristics of the the endothelial cells regulate the transcellular movement of materials across this barrier while other movement is paracellular. In this study the permeability of the endothelial cells to tritiated water (/sup 3/HHO) and /sup 14/C-labeled antipyrine (AP) was investigated. The cells were isolated non-enzymatically from calf pulmonary artery and were maintained in culture and used between the seventh and fifteenth passage. The cells were removed from the T-flasks with a rubber policeman, titurated with a 22g needle and centrifuged. The cells were mixed with an extracellular marker, drawn into polyethylene tubing and packed by centrifugation for use in the linear diffusion technique. All measurements were made at 37 C. The diffusion coefficients for /sup 3/HHO through the packed cells (D), the intracellular material (D/sub 2/), and the extracellular material (D/sub 1/) were 0.682, 0.932 and 2.45 x 10/sup -5/ cm/sup 2/ s/sup -1/ and for AP were 0.273, 0.355 and 1.13 x 10/sup -5/ cm/sup 2/ s/sup -1/ respectively. The permeability coefficient calculated by the series-parallel pathway model for /sup 3/HHO was higher than that for AP and for both /sup 3/HHO and AP were lower than those calculated for isolated lung cells and erythrocytes.

  20. Changes in rock salt permeability due to nearby excavation

    SciTech Connect

    Stormont, J C; Howard, C L

    1991-07-01

    Changes in brine and gas permeability of rock salt as a result of nearby excavation (mine-by) have been measured from the underground workings of the WIPP facility. Prior to the mine-by, the formation responds as a porous medium with a very low brine permeability, a significant pore (brine) pressure and no measurable gas permeability. The mine-by excavation creates a dilated, partially saturated zone in the immediate vicinity of the excavation with an increased permeability to brine and a measurable permeability to gas. The changes in hydrologic properties are discussed in the context of pore structure changes.

  1. Phase behavior and permeability properties of phospholipid bilayers containing a short-chain phospholipid permeability enhancer.

    PubMed

    Risbo, J; Jørgensen, K; Sperotto, M M; Mouritsen, O G

    1997-10-01

    The thermodynamic phase behavior and trans-bilayer permeability properties of multilamellar phospholipid vesicles containing a short-chain DC10PC phospholipid permeability enhancer have been studied by means of differential scanning calorimetry and fluorescence spectroscopy. The calorimetric scans of DC14PC lipid bilayer vesicles incorporated with high concentrations of DC10PC demonstrate a distinct influence on the lipid bilayer thermodynamics manifested as a pronounced freezing-point depression and a narrow phase coexistence region. Increasing amounts of DC10PC lead to a progressive lowering of the melting enthalpy, implying a mixing behavior of the DC10PC in the bilayer matrix similar to that of a substitutional impurity. The phase behavior of the DC10PC-DC14PC mixture is supported by fluorescence polarization measurements which, furthermore, in the low-temperature gel phase reveal a non-monotonic concentration-dependent influence on the structural bilayer properties; small concentrations of DC10PC induce a disordering of the acyl chains, whereas higher concentrations lead to an ordering. Irreversible fluorescence quench measurements demonstrate a substantial increase in the trans-bilayer permeability over broad temperature and composition ranges. At temperatures corresponding to the peak positions of the heat capacity, a maximum in the trans-bilayer permeability is observed. The influence of DC10PC on the lipid bilayer thermodynamics and the associated permeability properties is discussed in terms of microscopic effects on the lateral lipid organization and heterogeneity of the bilayer. PMID:9370247

  2. Evaluating Permeability Enchancement Using Electrical Techniques

    SciTech Connect

    John W. Pritchett

    2008-09-01

    Enhanced Geothermal Systems (EGS) development projects involve the artificial stimulation of relatively impermeable high-temperature underground regions (at depths of 2-4 kilometers or more) to create sufficient permeability to permit underground fluid circulation, so that hot water can be withdrawn from production wells and used to generate electric power. Several major research projects of this general type have been undertaken in the past in New Mexico (Fenton Hill), Europe, Japan and Australia. Recent U.S. activities along these lines focus mainly on stimulating peripheral areas of existing operating hydrothermal fields rather than on fresh 'greenfield' sites, but the long-term objective of the Department of Energy's EGS program is the development of large-scale power projects based on EGS technology (MIT, 2006; NREL, 2008). Usually, stimulation is accomplished by injecting water into a well at high pressure, enhancing permeability by the creation and propagation of fractures in the surrounding rock (a process known as 'hydrofracturing'). Beyond just a motivation, low initial system permeability is also an essential prerequisite to hydrofracturing. If the formation permeability is too high, excessive fluid losses will preclude the buildup of sufficient pressure to fracture rock. In practical situations, the actual result of injection is frequently to re-open pre-existing hydrothermally-mineralized fractures, rather than to create completely new fractures by rupturing intact rock. Pre-existing fractures can often be opened using injection pressures in the range 5-20 MPa. Creation of completely new fractures will usually require pressures that are several times higher. It is preferable to undertake development projects of this type in regions where tectonic conditions are conducive to shear failure, so that when pre-existing fractures are pressurized they will fail by shearing laterally. If this happens, the fracture will often stay open afterwards even if

  3. Membrane stress increases cation permeability in red cells.

    PubMed

    Johnson, R M

    1994-11-01

    The human red cell is known to increase its cation permeability when deformed by mechanical forces. Light-scattering measurements were used to quantitate the cell deformation, as ellipticity under shear. Permeability to sodium and potassium was not proportional to the cell deformation. An ellipticity of 0.75 was required to increase the permeability of the membrane to cations, and flux thereafter increased rapidly as the limits of cell extension were reached. Induction of membrane curvature by chemical agents also did not increase cation permeability. These results indicate that membrane deformation per se does not increase permeability, and that membrane tension is the effector for increased cation permeability. This may be relevant to some cation permeabilities observed by patch clamping. PMID:7858123

  4. Permeability-porosity relationships of subduction zone sediments

    USGS Publications Warehouse

    Gamage, K.; Screaton, E.; Bekins, B.; Aiello, I.

    2011-01-01

    Permeability-porosity relationships for sediments from the northern Barbados, Costa Rica, Nankai, and Peru subduction zones were examined based on sediment type, grain size distribution, and general mechanical and chemical compaction history. Greater correlation was observed between permeability and porosity in siliciclastic sediments, diatom oozes, and nannofossil chalks than in nannofossil oozes. For siliciclastic sediments, grouping of sediments by percentage of clay-sized material yields relationships that are generally consistent with results from other marine settings and suggests decreasing permeability as percentage of clay-sized material increases. Correction of measured porosities for smectite content improved the correlation of permeability-porosity relationships for siliciclastic sediments and diatom oozes. The relationship between permeability and porosity for diatom oozes is very similar to the relationship in siliciclastic sediments, and permeabilities of both sediment types are related to the amount of clay-size particles. In contrast, nannofossil oozes have higher permeability values by 1.5 orders of magnitude than siliciclastic sediments of the same porosity and show poor correlation between permeability and porosity. More indurated calcareous sediments, nannofossil chalks, overlap siliciclastic permeabilities at the lower end of their measured permeability range, suggesting similar consolidation patterns at depth. Thus, the lack of correlation between permeability and porosity for nannofossil oozes is likely related to variations in mechanical and chemical compaction at shallow depths. This study provides the foundation for a much-needed global database with fundamental properties that relate to permeability in marine settings. Further progress in delineating controls on permeability requires additional carefully documented permeability measurements on well-characterized samples. ?? 2010 Elsevier B.V.

  5. Permeability development during compaction of pumiceous dome lavas: testing the permeable foam collapse model

    NASA Astrophysics Data System (ADS)

    Ashwell, P.; Kendrick, J. E.; Lavallee, Y.; kennedy, B.; Hess, K.; von Aulock, F. W.; Cole, J. W.; Dingwell, D. B.

    2011-12-01

    The evolution of the porous network during lava dome extrusions is commonly perceived as the key control on the permeability which regulates the pore pressure, thereby challenging the stability of the dome. Here, we present experimental results of porosity and permeability evolution during compaction of aphiric and crystal-bearing rhyolitic, pumiceous (porosity ~60 %) lavas from Tarawera and Ngongotaha volcanoes (Taupo Volcanic Zone, New Zealand), respectively. The The Ngongotaha sample is from the crystal-free dome carapace (erupted ~200 ka following caldera collapse at Rotorua Caldera), while the Tarawera sample is a crystalline, pumiceous clast from a dome-collapse generated block and ash flow (at Okataina Caldera ~1314 AD). This study tests the validity of the 'permeable foam' model by comparing properties of the experimentally compacted pumice to denser material seen in the exposed cores of Tarawera and Ngongotaha. Cylindrical samples were deformed under an axial stress of 2.8 MPa at 650-750°C (above their calorimetric glass transition temperature) up a total axial strain of 50 %. The porosity and permeability of the samples were characterized at strain increments of 10 %. The samples exhibit strain hardening during compaction. A rapid reduction in permeability along the primary axis occurs during the initial stage of compression and continues to decrease with increasing strain and densification of the lava. Development of permeability of each lava differs as the crystallinity affects the compaction process. The development of textures and microstructures is characterised using petrographic analysis and neutron computed tomography. The findings from the study are then put into the context of lava dome growth at Tarawera and Ngongotaha volcanoes.

  6. EPA/ITRC-RTDF permeable reactive barrier short course. Permeable reactive barriers: Application and deployment

    SciTech Connect

    Not Available

    1999-01-01

    This report focuses on the following: Permeable Reactive Barriers: Application and Deployment; Introduction to Permeable Reactive Barriers (PRBs) for Remediating and Managing Contaminated Groundwater in Situ; Collection and Interpretation of Design Data 1: Site Characterization for PRBs; Reactive Materials: Zero-Valent Iron; Collection and Interpretation of Design Data 2: Laboratory and Pilot Scale Tests; Design Calculations; Compliance Monitoring, Performance Monitoring and Long-Term Maintenance for PRBs; PRB Emplacement Techniques; PRB Permitting and Implementation; Treatment of Metals; Non-Metallic Reactive Materials; Economic Considerations for PRB Deployment; and Bibliography.

  7. EPA/ITRC-RTDF permeable reactive barrier short course. Permeable reactive barriers: Application and deployment

    SciTech Connect

    1999-11-01

    This report focuses on the following: Permeable Reactive Barriers: Application and Deployment; Introduction to Permeable Reactive Barriers (PRBs) for Remediating and Managing Contaminated Groundwater in Situ; Collection and Interpretation of Design Data 1: Site Characterization for PRBs; Reactive Materials: Zero-Valent Iron; Collection and Interpretation of Design Data 2: Laboratory and Pilot Scale Tests; Design Calculations; Compliance Monitoring, Performance Monitoring and Long-Term Maintenance for PRBs; PRB Emplacement Techniques; PRB Permitting and Implementation; Treatment of Metals; Non-Metallic Reactive Materials; Economic Considerations for PRB Deployment; and Bibliography.

  8. Clamshell excavation of a permeable reactive barrier

    NASA Astrophysics Data System (ADS)

    Molfetta, Antonio Di; Sethi, Rajandrea

    2006-06-01

    Nowadays, permeable reactive barriers (PRB) are one of the most widespread techniques for the remediation of contaminated aquifers. Over the past 10 years, the use of iron-based PRBs has evolved from innovative to accepted standard practice for the treatment of a variety of groundwater contaminants (ITRC in: Permeable reactive barriers: lessons learned/new directions. The Interstate Technology and Regulatory Council, Permeable Reactive Barriers Team 2005). Although, a variety of excavation methods have been developed, backhoe excavators are often used for the construction of PRBs. The aim of this study is to describe the emplacement of a full-scale PRB and the benefits deriving from the use of a crawler crane equipped with a hydraulic grab (also known as clamshell excavator) in the excavation phases. The studied PRB was designed to remediate a chlorinated hydrocarbons plume at an old industrial landfill site, in Avigliana, near the city of Torino, in Italy. The continuous reactive barrier was designed to be 120 m long, 13 m deep, and 0.6 m thick. The installation of the barrier was accomplished using a clamshell for the excavation of the trench and a guar-gum slurry to support the walls. The performance of this technique was outstanding and allowed the installation of the PRB in 7 days. The degree of precision of the excavation was very high because of the intrinsic characteristics of this excavation tool and of the use of a concrete curb to guide the hydraulic grab. Moreover, the adopted technique permitted a saving of bioslurry thus minimizing the amount of biocide required.

  9. Engineered Trehalose Permeable to Mammalian Cells

    PubMed Central

    Abazari, Alireza; Meimetis, Labros G.; Budin, Ghyslain; Bale, Shyam Sundhar; Weissleder, Ralph; Toner, Mehmet

    2015-01-01

    Trehalose is a naturally occurring disaccharide which is associated with extraordinary stress-tolerance capacity in certain species of unicellular and multicellular organisms. In mammalian cells, presence of intra- and extracellular trehalose has been shown to confer improved tolerance against freezing and desiccation. Since mammalian cells do not synthesize nor import trehalose, the development of novel methods for efficient intracellular delivery of trehalose has been an ongoing investigation. Herein, we studied the membrane permeability of engineered lipophilic derivatives of trehalose. Trehalose conjugated with 6 acetyl groups (trehalose hexaacetate or 6-O-Ac-Tre) demonstrated superior permeability in rat hepatocytes compared with regular trehalose, trehalose diacetate (2-O-Ac-Tre) and trehalose tetraacetate (4-O-Ac-Tre). Once in the cell, intracellular esterases hydrolyzed the 6-O-Ac-Tre molecules, releasing free trehalose into the cytoplasm. The total concentration of intracellular trehalose (plus acetylated variants) reached as high as 10 fold the extracellular concentration of 6-O-Ac-Tre, attaining concentrations suitable for applications in biopreservation. To describe this accumulation phenomenon, a diffusion-reaction model was proposed and the permeability and reaction kinetics of 6-O-Ac-Tre were determined by fitting to experimental data. Further studies suggested that the impact of the loading and the presence of intracellular trehalose on cellular viability and function were negligible. Engineering of trehalose chemical structure rather than manipulating the cell, is an innocuous, cell-friendly method for trehalose delivery, with demonstrated potential for trehalose loading in different types of cells and cell lines, and can facilitate the wide-spread application of trehalose as an intracellular protective agent in biopreservation studies. PMID:26115179

  10. The kinetics of denitrification in permeable sediments

    NASA Astrophysics Data System (ADS)

    Evrard, Victor; Glud, Ronnie N.; Cook, Perran L. M.

    2013-04-01

    Permeable sediments comprise the majority of shelf sediments, yet the rates of denitrification remain highly uncertain in these environments. Computational models are increasingly being used to understand the dynamics of denitrification in permeable sediments, which are complex environments to study experimentally. The realistic implementation of such models requires reliable experimentally derived data on the kinetics of denitrification. Here we undertook measurements of denitrification kinetics as a function of nitrate concentration and in the presence and absence of oxygen, in carefully controlled flow through reactor experiments on sediments taken from six shallow coastal sites in Port Phillip Bay, Victoria, Australia. The results showed that denitrification commenced rapidly (within 30 min) after the onset of anoxia and the kinetics could be well described by Michaelis-Menten kinetics with half saturation constants (apparent Km) ranging between 1.5 and 19.8 μM, and maximum denitrification rate (Vmax) were in the range of 0.9-7.5 nmol mL-1 h-1. The production of N2 through anaerobic ammonium oxidation (anammox) was generally found to be less than 10% that of denitrification. Vmax were in the same range as previously reported in cohesive sediments despite organic carbon contents one order of magnitude lower for the sediments studied here. The ratio of sediment O2 consumption to Vmax was in the range of 0.02-0.09, and was on average much lower than the theoretical ratio of 0.8. The most likely explanation for this is that the microbial community is not able to instantaneously shift or optimally use a particular electron acceptor in the highly dynamic redox environment experienced in permeable sediments. Consistent with this explanation, subsequent longer-term experiments over 5 days showed that denitrification rates increased by a factor of 10 within 3 days of the permanent onset of anoxia. In contrast to previous studies, we did not observe any significant

  11. Small intestinal permeability in older adults

    PubMed Central

    Valentini, Luzia; Ramminger, Sara; Haas, Verena; Postrach, Elisa; Werich, Martina; Fischer, André; Koller, Michael; Swidsinski, Alexander; Bereswill, Stefan; Lochs, Herbert; Schulzke, Jörg‐Dieter

    2014-01-01

    Abstract It is not yet clear whether intestinal mucosal permeability changes with advancing age in humans. This question is of high importance for drug and nutrition approaches for older adults. Our main objective was to answer the question if small intestinal barrier integrity deteriorates with healthy aging. We conducted a cross‐sectional study including the pooled data of 215 nonsmoking healthy adults (93 female/122 male), 84 of whom were aged between 60 and 82 years. After a 12‐h fast, all participants ingested 10 g of lactulose and 5 g of mannitol. Urine was collected for 5 h afterwards and analyzed for test sugars. The permeability index (PI = lactulose/mannitol) was used to assess small intestinal permeability. Low‐grade inflammation defined by high‐sensitivity C‐reactive protein ≥1 mL/L and kidney function (estimated glomerular filtration rate) were determined in the older age group. The PI was similar in older compared to younger adults (P =0.887). However, the urinary recovery of lactulose and mannitol was lower in the older adults and this change was neither associated with urinary volume nor glomerular filtration rate. The PI was not significantly correlated with low‐grade inflammation or presence of noninsulin‐dependent type 2 diabetes. However, it significantly deteriorated in the copresence of both conditions compared to low‐grade inflammation alone (P =0.043) or type 2 diabetes alone (P =0.015). Small intestinal mucosal barrier does not deteriorate with age per se. But low‐grade inflammation coupled with minor disease challenges, such as type 2 diabetes, can compromise the small intestinal barrier. PMID:24771689

  12. Antibiotic Treatment Affects Intestinal Permeability and Gut Microbial Composition in Wistar Rats Dependent on Antibiotic Class

    PubMed Central

    Tulstrup, Monica Vera-Lise; Christensen, Ellen Gerd; Carvalho, Vera; Linninge, Caroline; Ahrné, Siv; Højberg, Ole; Licht, Tine Rask; Bahl, Martin Iain

    2015-01-01

    Antibiotics are frequently administered orally to treat bacterial infections not necessarily related to the gastrointestinal system. This has adverse effects on the commensal gut microbial community, as it disrupts the intricate balance between specific bacterial groups within this ecosystem, potentially leading to dysbiosis. We hypothesized that modulation of community composition and function induced by antibiotics affects intestinal integrity depending on the antibiotic administered. To address this a total of 60 Wistar rats (housed in pairs with 6 cages per group) were dosed by oral gavage with either amoxicillin (AMX), cefotaxime (CTX), vancomycin (VAN), metronidazole (MTZ), or water (CON) daily for 10–11 days. Bacterial composition, alpha diversity and caecum short chain fatty acid levels were significantly affected by AMX, CTX and VAN, and varied among antibiotic treatments. A general decrease in diversity and an increase in the relative abundance of Proteobacteria was observed for all three antibiotics. Additionally, the relative abundance of Bifidobacteriaceae was increased in the CTX group and both Lactobacillaceae and Verrucomicrobiaceae were increased in the VAN group compared to the CON group. No changes in microbiota composition or function were observed following MTZ treatment. Intestinal permeability to 4 kDa FITC-dextran decreased after CTX and VAN treatment and increased following MTZ treatment. Plasma haptoglobin levels were increased by both AMX and CTX but no changes in expression of host tight junction genes were found in any treatment group. A strong correlation between the level of caecal succinate, the relative abundance of Clostridiaceae 1 family in the caecum, and the level of acute phase protein haptoglobin in blood plasma was observed. In conclusion, antibiotic-induced changes in microbiota may be linked to alterations in intestinal permeability, although the specific interactions remain to be elucidated as changes in permeability did

  13. Laser Additive Manufacturing of Gas Permeable Structures

    NASA Astrophysics Data System (ADS)

    Klahn, C.; Bechmann, F.; Hofmann, S.; Dinkel, M.; Emmelmann, C.

    Laser additive manufacturing offers a variety of new design possibilities. In mold making laser additive manufactured inserts with conformal cooling channels are already state of the art. Pneumatic ejectors for injection molds are a new application for laser additive manufacturing. The pneumatic ejectors require a durable gas permeable material. This material is produced by placing the scan vectors for the laser additive manufacturing process in a defined pattern. Trials with different plastics proofed the function and reliability of the pneumatic ejector concept in the injection molding cycle.

  14. Gas permeability measurements for film envelope materials

    DOEpatents

    Ludtka, G.M.; Kollie, T.G.; Watkin, D.C.; Walton, D.G.

    1998-05-12

    Method and apparatus for measuring the permeability of polymer film materials such as used in super-insulation powder-filled evacuated panels (PEPs) reduce the time required for testing from several years to weeks or months. The method involves substitution of a solid non-outgassing body having a free volume of between 0% and 25% of its total volume for the usual powder in the PEP to control the free volume of the ``body-filled panel.`` Pressure versus time data for the test piece permit extrapolation to obtain long term performance of the candidate materials. 4 figs.

  15. Gas permeability measurements for film envelope materials

    DOEpatents

    Ludtka, Gerard M.; Kollie, Thomas G.; Watkin, David C.; Walton, David G.

    1998-01-01

    Method and apparatus for measuring the permeability of polymer film materials such as used in super-insulation powder-filled evacuated panels (PEPs) reduce the time required for testing from several years to weeks or months. The method involves substitution of a solid non-outgassing body having a free volume of between 0% and 25% of its total volume for the usual powder in the PEP to control the free volume of the "body-filled panel". Pressure versus time data for the test piece permit extrapolation to obtain long term performance of the candidate materials.

  16. Method for decreasing permeability around a wellbore

    SciTech Connect

    Richardson, W.C.; Whittington, L.E.; Morrow, L.R.

    1988-01-26

    A method for decreasing formation permeability in an underground formation around a wellbore is described comprising: injecting an aqueous solution having a pH of about 0.9 to about 3.5 into the formation surrounding a wellbore, the aqueous solution comprising about 2% to about 20% by weight of lignosulfonate, about 2% to about 20% by weight of monomer of acrylic acid, a sufficient amount of an initiator of persulfate to copolymerize the lignosulfonate and the monomer, and about 0% to about 3.0% by weight of a metal slat having a cation of iron, titanium, vanadium, chromium or molybdenum.

  17. Nerve impulses increase glial intercellular permeability.

    PubMed

    Marrero, H; Orkand, R K

    1996-03-01

    Coordinating the activity of neurons and their satellite glial cells requires mechanisms by which glial cells detect neuronal activity and change their properties as a result. This study monitors the intercellular diffusion of the fluorescent dye Lucifer Yellow (LY), following its injection into glial cells of the frog optic nerve, and demonstrates that nerve impulses increase the permeability of interglial gap junctions. Consequently, the spatial buffer capacity of the neuroglial cell syncytium for potassium, other ions, and small molecules will be enhanced; this may facilitate glial function in maintaining homeostasis of the neuronal microenvironment. PMID:8833199

  18. Gas permeable electrode for electrochemical system

    DOEpatents

    Ludwig, Frank A.; Townsend, Carl W.

    1989-01-01

    An electrode apparatus adapted for use in electrochemical systems having an anode compartment and a cathode compartment in which gas and ions are produced and consumed in the compartments during generation of electrical current. The electrode apparatus includes a membrane for separating the anode compartment from the cathode compartment wherein the membrane is permeable to both ions and gas. The cathode and anode for the assembly are provided on opposite sides of the membrane. During use of the membrane-electrode apparatus in electrochemical cells, the gas and ions generated at the cathode or anode migrate through the membrane to provide efficient transfer of gas and ions between the anode and cathode compartments.

  19. PERMEABILITY OF SALTSTONE MEASUREMENT BY BEAM BENDING

    SciTech Connect

    Harbour, J; Tommy Edwards, T; Vickie Williams, V

    2008-01-30

    One of the goals of the Saltstone variability study is to identify (and, quantify the impact of) the operational and compositional variables that control or influence the important processing and performance properties of Saltstone mixes. A performance property for Saltstone mixes that is important but not routinely measured is the liquid permeability or saturated hydraulic conductivity of the cured Saltstone mix. The value for the saturated hydraulic conductivity is an input into the Performance Assessment for the SRS Z-Area vaults. Therefore, it is important to have a method available that allows for an accurate and reproducible measurement of permeability quickly and inexpensively. One such method that could potentially meet these requirements for the measurement of saturated hydraulic conductivity is the technique of beam bending, developed by Professor George Scherer at Princeton University. In order to determine the feasibility of this technique for Saltstone mixes, a summer student, David Feliciano, was hired to work at Princeton under the direction of George Scherer. This report details the results of this study which demonstrated the feasibility and applicability of the beam bending method to measurement of permeability of Saltstone samples. This research effort used samples made at Princeton from a Modular Caustic side solvent extraction Unit based simulant (MCU) and premix at a water to premix ratio of 0.60. The saturated hydraulic conductivities for these mixes were measured by the beam bending technique and the values determined were of the order of 1.4 to 3.4 x 10{sup -9} cm/sec. These values of hydraulic conductivity are consistent with independently measured values of this property on similar MCU based mixes by Dixon and Phifer. These values are also consistent with the hydraulic conductivity of a generic Saltstone mix measured by Langton in 1985. The high water to premix ratio used for Saltstone along with the relatively low degree of hydration for

  20. Experimental Observations of Permeability Enhancements by Dynamic Stresses

    NASA Astrophysics Data System (ADS)

    Elkhoury, J. E.; Niemeijer, A.; Brodsky, E. E.; Marone, C.

    2008-12-01

    Shaking produced by seismic faulting often triggers distant and nearby earthquakes. Seismic waves are also known to increase stream flow and spring discharge and enhance oil production; in some cases tripling the effective permeability of the natural system. These observations have been attributed to shaking-induced increases in permeability. However, the underlying mechanism is poorly understood. Here we present experimental evidence of permeability enhancement in fractured rock samples subject to dynamic stresses. We use Berea sandstone samples under triaxial stresses with confining pressure of 9 MPa and 20 MPa of normal stress. We flow deionized water through a fracture produced in-situ and find that oscillations in pore pressure, of 20 second period and 120 second duration, induce transient increases in permeability. Permeability increases scale with the amplitude of pore pressure oscillations. The maximum value of the permeability enhancement is 5x10-16 m2 over a background permeability of 1x10-15 m2. After the oscillations, permeability recovers as the inverse square root of time. The recovery indicates a reversible mechanism, such as clogging/unclogging of fractures, as opposed to an irreversible one, like micro-fracturing. Our result has clear consequences for earthquake triggering mediated by permeability enhancement. Moreover, our data point at the feasibility of dynamically controlling permeability of fractured systems with applications to hydrology and oil reservoir engineering.

  1. Direct numerical simulation of turbulent channel flow with permeable walls

    NASA Astrophysics Data System (ADS)

    Hahn, Seonghyeon; Je, Jongdoo; Choi, Haecheon

    2002-01-01

    The main objectives of this study are to suggest a proper boundary condition at the interface between a permeable block and turbulent channel flow and to investigate the characteristics of turbulent channel flow with permeable walls. The boundary condition suggested is an extended version of that applied to laminar channel flow by Beavers & Joseph (1967) and describes the behaviour of slip velocities in the streamwise and spanwise directions at the interface between the permeable block and turbulent channel flow. With the proposed boundary condition, direct numerical simulations of turbulent channel flow that is bounded by the permeable wall are performed and significant skin-friction reductions at the permeable wall are obtained with modification of overall flow structures. The viscous sublayer thickness is decreased and the near-wall vortical structures are significantly weakened by the permeable wall. The permeable wall also reduces the turbulence intensities, Reynolds shear stress, and pressure and vorticity fluctuations throughout the channel except very near the wall. The increase of some turbulence quantities there is due to the slip-velocity fluctuations at the wall. The boundary condition proposed for the permeable wall is validated by comparing solutions with those obtained from a separate direct numerical simulation using both the Brinkman equation for the interior of a permeable block and the Navier Stokes equation for the main channel bounded by a permeable block.

  2. Salt-saturated concrete strength and permeability

    SciTech Connect

    Pfeifle, T.W.

    1996-11-01

    Laboratory-scale experiments applicable to the use of salt-saturated concrete as a seal material for a transuranic waste repository have been completed. Nitrogen gas permeability measurements were made using a flexible-wall permeameter, a confining pressure of 1 MPa, and gas pressure gradients ranging from 0.3 MPa to 0.75 MPa. Results show that salt-saturated concrete has very low intrinsic permeability with values ranging from 9.4 {times} 10{sup {minus}22} m{sup 2} to 9.7 {times} 10{sup {minus}17} m{sup 2}. Strength and deformation characteristics were investigated under conditions of triaxial compression with confining pressures ranging from 0 to 15 MPa using either axial strain-rate or axial stress-rate control and show that the failure strength of concrete increases with confining pressure which can be adequately described through pressure-sensitive failure criteria. Axial, radial, and volumetric strains were also measured during each test and these data were used to determine elastic properties. Experimental results are applicable in the design and analysis of scale-related functions and apply to other concrete structures subjected to compressive loadings such as dams and prestressed structural members.

  3. Vortex Ring Interaction with Multiple Permeable Screens

    NASA Astrophysics Data System (ADS)

    Musta, Mustafa N.; Krueger, Paul S.

    2008-11-01

    Previous experiments on the interaction of a vortex ring impinging on single thin permeable screen demonstrated the formation of secondary vortices and a transmitted vortex ring. The present work concerns experimental investigation of the interaction of a vortex ring with multiple permeable screens. Vortex rings are formed by piston-cylinder type vortex ring generator and impinge on an array of parallel, transparent screens. The screens have an open ratio of 84% and the spacing between screens is variable. The vortex rings were formed with an approximate jet Reynolds number of 1300 and a piston stroke-to-jet diameter ratio (L/D) of approximately 4. Dye visualization of the vortex rings shows that they break into multiple vortices after impinging on first screen The vortices subsequently disintegrate, but the total distance required for disintegration is relatively unaffected by the number of screens through with the vortices pass due to the regular structure of the screens. It is also observed that the location of the initial vortex ring axis relative to the screen rods has a significant effect on the vortex breakup and disintegration process.

  4. Modeling of microvascular permeability changes after electroporation.

    PubMed

    Corovic, Selma; Markelc, Bostjan; Dolinar, Mitja; Cemazar, Maja; Jarm, Tomaz

    2015-01-01

    Vascular endothelium selectively controls the transport of plasma contents across the blood vessel wall. The principal objective of our preliminary study was to quantify the electroporation-induced increase in permeability of blood vessel wall for macromolecules, which do not normally extravasate from blood into skin interstitium in homeostatic conditions. Our study combines mathematical modeling (by employing pharmacokinetic and finite element modeling approach) with in vivo measurements (by intravital fluorescence microscopy). Extravasation of fluorescently labeled dextran molecules of two different sizes (70 kDa and 2000 kDa) following the application of electroporation pulses was investigated in order to simulate extravasation of therapeutic macromolecules with molecular weights comparable to molecular weight of particles such as antibodies and plasmid DNA. The increase in blood vessel permeability due to electroporation and corresponding transvascular transport was quantified by calculating the apparent diffusion coefficients for skin microvessel wall (D [μm2/s]) for both molecular sizes. The calculated apparent diffusion coefficients were D = 0.0086 μm2/s and D = 0.0045 μm2/s for 70 kDa and 2000 kDa dextran molecules, respectively. The results of our preliminary study have important implications in development of realistic mathematical models for prediction of extravasation and delivery of large therapeutic molecules to target tissues by means of electroporation. PMID:25793292

  5. Blood-ocular barrier permeability in monkeys.

    PubMed Central

    Yoshida, A; Ishiko, S; Kojima, M; Lipsky, S N

    1992-01-01

    The permeability of the blood-ocular barrier was investigated in five monkeys using vitreous fluorophotometry (VFP). Inward permeability (Pin) of the blood-retinal barrier was calculated by a computer simulation method. Kinetic VFP was performed after intravitreal injection of fluorescein (F) or fluorescein monoglucuronide (FG). The estimated mean value of Pin (x10(-6) cm/min) was 4.8 (SD 1.2). The mean rates of loss (per hour) of F from the anterior chamber (Ka) and the vitreous (Kv) were 0.11 (SD 0.01) and 0.13 (SD 0.03), respectively, which were approximately three and four times greater than those of FG (0.04 (SD 0.01) and 0.03 (SD 0.01), respectively). Probenecid administered intraperitoneally decreased both the Ka and the Kv of F significantly but had no effect on the Ka or the Kv of FG, suggesting that F was excreted from the eye with the aid of the active transport mechanism. The results of comparative studies of the rates of loss of F from the anterior chamber (Ka) and from the vitreous (Kv) suggested that active transport was more predominant in the blood-retinal barrier than in the blood-aqueous barrier. PMID:1739721

  6. Efficient high-permeability fracturing offshore

    SciTech Connect

    Phillipi, M.; Farabee, M.

    1996-12-31

    Offshore operators can more efficiently and effectively perform high-permeability and conventional hydraulic fracture treatments by blending treatment slurries under microprocessor control, adding undiluted acid on-the-fly, and altering sand concentrations and other slurry properties instantaneously. A two-skid system has been designed with these considerations in mind. The system, which can be shipped efficiently in ISO containers, has been tested on fluids up to 210-cp viscosity and can step or ramp sand concentrations up to a maximum of 20 lb/gal. All additives, including acid treatments, are added on-the-fly; leftover additives and acids may be stored for future jobs. The system may be applied in most conditions, including offshore wells requiring conventional or high-permeability fracture treatments and certain land-based wells in remote areas where a compact skid is needed. Three significant benefits have resulted from using the compact-skid system: offshore operators have been able to ship the skid system at 20% of shipping costs of non-ISO equipment; on-the-fly mixing has prevented material waste associated with batch-mixing; and volumes pumped on actual jobs have closely matched job designs. Data have been collected from several Gulf of Mexico jobs run with the two-part skid system that has been designed for conducting hydraulic fracture treatments from offshore rigs.

  7. Modeling of Microvascular Permeability Changes after Electroporation

    PubMed Central

    Corovic, Selma; Markelc, Bostjan; Dolinar, Mitja; Cemazar, Maja; Jarm, Tomaz

    2015-01-01

    Vascular endothelium selectively controls the transport of plasma contents across the blood vessel wall. The principal objective of our preliminary study was to quantify the electroporation-induced increase in permeability of blood vessel wall for macromolecules, which do not normally extravasate from blood into skin interstitium in homeostatic conditions. Our study combines mathematical modeling (by employing pharmacokinetic and finite element modeling approach) with in vivo measurements (by intravital fluorescence microscopy). Extravasation of fluorescently labeled dextran molecules of two different sizes (70 kDa and 2000 kDa) following the application of electroporation pulses was investigated in order to simulate extravasation of therapeutic macromolecules with molecular weights comparable to molecular weight of particles such as antibodies and plasmid DNA. The increase in blood vessel permeability due to electroporation and corresponding transvascular transport was quantified by calculating the apparent diffusion coefficients for skin microvessel wall (D [μm2/s]) for both molecular sizes. The calculated apparent diffusion coefficients were D = 0.0086 μm2/s and D = 0.0045 μm2/s for 70 kDa and 2000 kDa dextran molecules, respectively. The results of our preliminary study have important implications in development of realistic mathematical models for prediction of extravasation and delivery of large therapeutic molecules to target tissues by means of electroporation. PMID:25793292

  8. Air sparging in low permeability soils

    SciTech Connect

    Marley, M.C.

    1996-08-01

    Sparging technology is rapidly growing as a preferred, low cost remediation technique of choice at sites across the United States. The technology is considered to be commercially available and relatively mature. However, the maturity is based on the number of applications of the technology as opposed to the degree of understanding of the mechanisms governing the sparging process. Few well documented case studies exist on the long term operation of the technology. Sparging has generally been applied using modified monitoring well designs in uniform, coarse grained soils. The applicability of sparging for the remediation of DNAPLs in low permeability media has not been significantly explored. Models for projecting the performance of sparging systems in either soils condition are generally simplistic but can be used to provide general insight into the effects of significant changes in soil and fluid properties. The most promising sparging approaches for the remediation of DNAPLs in low permeability media are variations or enhancements to the core technology. Recirculatory sparging systems, sparging/biosparging trenches or curtains and heating or induced fracturing techniques appear to be the most promising technology variants for this type of soil. 21 refs., 9 figs.

  9. Reservoir permeability from seismic attribute analysis

    SciTech Connect

    Silin, Dmitriy; Goloshubin, G.; Silin, D.; Vingalov, V.; Takkand, G.; Latfullin, M.

    2008-02-15

    In case of porous fluid-saturated medium the Biot's poroelasticity theory predicts a movement of the pore fluid relative to the skeleton on seismic wave propagation through the medium. This phenomenon opens an opportunity for investigation of the flow properties of the hydrocarbon-saturated reservoirs. It is well known that relative fluid movement becomes negligible at seismic frequencies if porous material is homogeneous and well cemented. In this case the theory predicts an underestimated seismic wave velocity dispersion and attenuation. Based on Biot's theory, Helle et al. (2003) have numerically demonstrated the substantial effects on both velocity and attenuation by heterogeneous permeability and saturation in the rocks. Besides fluid flow effect, the effects of scattering (Gurevich, et al., 1997) play very important role in case of finely layered porous rocks and heterogeneous fluid saturation. We have used both fluid flow and scattering effects to derive a frequency-dependent seismic attribute which is proportional to fluid mobility and applied it for analysis of reservoir permeability.

  10. Tight junction, selective permeability, and related diseases.

    PubMed

    Krug, Susanne M; Schulzke, Jörg D; Fromm, Michael

    2014-12-01

    The tight junction forms a barrier against unlimited paracellular passage but some of the tight junction proteins just do the opposite, they form extracellular channels zigzagging between lateral membranes of neighboring cells. All of these channel-forming proteins and even some of the barrier formers exhibit selectivity, which means that they prefer certain substances over others. All channel formers exhibit at least one of the three types of selectivity: for cations (claudin-2, -10b, -15), for anions (claudin-10a, -17) or for water (claudin-2). Also some, but not all, barrier-forming claudins are charge-selective (claudin-4, -8, -14). Moreover, occludin and tricellulin turned out to be relevant for barrier formation against macromolecule passage. Tight junction proteins are dysregulated or can be genetically defective in numerous diseases, which may lead to three effects: (i) impaired paracellular transport e.g. causing magnesium loss in the kidney, (ii) increased paracellular transport of solutes and water e.g. causing leak-flux diarrhea in the intestine, and (iii) increased permeability to large molecules e.g. unwanted intestinal pathogen uptake fueling inflammatory processes. This review gives an overview on the properties of tight junction proteins featuring selective permeability, and in this context explains how these proteins induce or aggravate diseases. PMID:25220018

  11. What about temperature? Measuring permeability at magmatic conditions.

    NASA Astrophysics Data System (ADS)

    Kushnir, Alexandra R. L.; Martel, Caroline; Champallier, Rémi; Reuschlé, Thierry

    2015-04-01

    The explosive potential of volcanoes is intimately linked to permeability, which is governed by the connectivity of the porous structure of the magma and surrounding edifice. As magma ascends, volatiles exsolve from the melt and expand, creating a gas phase within the conduit. In the absence of a permeable structure capable of dissipating these gases, the propulsive force of an explosive eruption arises from the gas expansion and the build up of subsurface overpressures. Thus, characterizing the permeability of volcanic rocks under in-situ conditions (high temperature and pressure) allows us to better understand the outgassing potential and explosivity of volcanic systems. Current studies of the permeabilities of volcanic rocks generally measure permeability at room temperature using gas permeameters or model permeability using analytic imaging. Our goal is to perform and assess permeability measurements made at high temperature and high pressure in the interest of approaching the permeability of the samples at magmatic conditions. We measure the permeability of andesitic samples expelled during the 2010 Mt. Merapi eruption. We employ and compare two protocols for measuring permeability at high temperature and under high pressure using argon gas in an internally heated Paterson apparatus with an isolated pore fluid system. We first use the pulse decay method to measure the permeability of our samples, then compare these values to permeability measurements performed under steady state flow. We consider the steady state flow method the more rigorous of the two protocols, as we are more capable of accounting for the temperature gradient within the entire pore fluid system. At temperatures in excess of 700°C and pressures of 100 MPa, permeability values plummet by several orders of magnitude. These values are significantly lower than those commonly reported for room temperature permeameter measurements. The reduction in permeability at high temperature is a

  12. Experimental Investigation on Sandstone Rock Permeability of Pakistan Gas Fields

    NASA Astrophysics Data System (ADS)

    Raza, Arshad; Bing, Chua Han; Nagarajan, Ramasamy; Hamid, Mohamed Ali

    2015-04-01

    Permeability is the ability of formation to produce hydrocarbon which is affected by compaction, pore size, sorting, cementation, layering and clay swelling. The effect of texture on permeability in term of grain size, sorting, sphericity, degree of cementing has been reported in literature. Also, the effect of permeability on capillary pressure, irreducible water saturation, displacement pressure and pore geometry constant has been studied separately. This preliminary study presents the experimental results of eight samples to understand the effect of similar factors of texture on permeability. With the knowledge of the results, it can be said that the effect of grain size, cementation, texture material, sphericity, and porosity can't be observed on permeability except sorting when less than ten samples are considered from different depositional environment. The results also show the impact of permeability on capillary pressure, irreducible water saturation, and displacement pressure and pore geometry index as similar as published in the literature.

  13. Calculation of large scale relative permeabilities from stochastic properties of the permeability field and fluid properties

    SciTech Connect

    Lenormand, R.; Thiele, M.R.

    1997-08-01

    The paper describes the method and presents preliminary results for the calculation of homogenized relative permeabilities using stochastic properties of the permeability field. In heterogeneous media, the spreading of an injected fluid is mainly sue to the permeability heterogeneity and viscosity fingering. At large scale, when the heterogeneous medium is replaced by a homogeneous one, we need to introduce a homogenized (or pseudo) relative permeability to obtain the same spreading. Generally, is derived by using fine-grid numerical simulations (Kyte and Berry). However, this operation is time consuming and cannot be performed for all the meshes of the reservoir. We propose an alternate method which uses the information given by the stochastic properties of the field without any numerical simulation. The method is based on recent developments on homogenized transport equations (the {open_quotes}MHD{close_quotes} equation, Lenormand SPE 30797). The MHD equation accounts for the three basic mechanisms of spreading of the injected fluid: (1) Dispersive spreading due to small scale randomness, characterized by a macrodispersion coefficient D. (2) Convective spreading due to large scale heterogeneities (layers) characterized by a heterogeneity factor H. (3) Viscous fingering characterized by an apparent viscosity ration M. In the paper, we first derive the parameters D and H as functions of variance and correlation length of the permeability field. The results are shown to be in good agreement with fine-grid simulations. The are then derived a function of D, H and M. The main result is that this approach lead to a time dependent . Finally, the calculated are compared to the values derived by history matching using fine-grid numerical simulations.

  14. Method for plugging high permeability zones in subterranean reservoirs

    SciTech Connect

    Clauset, A.O. Jr.; Christopher, C.A. Jr.

    1980-07-01

    An aqueous solution comprising fresh water and a pectic substance selected from the group consisting of pectins, pectates, polygalacturonic acids, and mixtures thereof is injected into a subterranean petroleum reservoir containing high permeability areas within the reservoirs. Upon entering these high permeability areas the injected aqueous solution contacts a brine which causes the pectate substance to form a gel, thereby effectively plugging the high permeability areas within the reservoir. 13 claims.

  15. Permeability of stemming materials for prompt gas sampling

    SciTech Connect

    Beiriger, J.; Trimmer, D.

    1982-01-01

    The permeability and porosity of a suite of man-made granular aggregates and stemming materials currently in use at NTS was measured in 1-D loading as a function of stress. In all cases, the gas permeability was measured at 22 MPa after cycling up and down from 100 to 1200 MPa. Depending on stress and material, permeability decreased up to three orders of magnitude, porosity up to 63% and the sample compacted by as much as 35%. Steel ball bearings were found to retain the highest permeability of all the materials tested. The enhancement of prompt gas sampling through alternate stemming material in the column above the nuclear device is discussed.

  16. Stress induced permeability anisotropy of Resedimented Boston Blue Clay

    NASA Astrophysics Data System (ADS)

    Adams, Amy L.; Germaine, John T.; Flemings, Peter B.; Day-Stirrat, Ruarri J.

    2013-10-01

    In Resedimented Boston Blue Clay (RBBC), a low-plasticity glacio-marine illitic mudrock, the ratio of the horizontal to vertical permeability (the permeability anisotropy, rk) increases from 1.2 to 1.9 as the porosity decreases from 0.5 to 0.37 and the permeability decreases by more than 1 order of magnitude. Backscattered Scanning Electron Microscope (BSEM) images taken at formation stress levels reveal that particles rotate perpendicular to the axial loading direction by ˜22°, with larger particles rotating more significantly and achieving more uniform alignment than smaller particles. We show experimentally that preferred platy particle orientation can explain our permeability anisotropy measurements. The permeability anisotropy of mechanically compressed mudrocks is minimal, <2.5. We use a novel approach (cubic specimens) to measure the evolution of permeability anisotropy in different directions on the same specimen, unlike most other methods. Modified analytic techniques allow calculation of the permeability anisotropy for a specimen using directional constant head permeability methods. A better understanding of the evolution of permeability anisotropy during sediment burial is important for modeling subsurface transport processes, including hydrocarbon migration and contaminant transport, as well as estimating in situ conditions such as pore pressure, overpressure, and effective stress.

  17. Cutaneous thermal injury alters macromolecular permeability of rat small intestine.

    PubMed

    Carter, E A; Tompkins, R G; Schiffrin, E; Burke, J F

    1990-03-01

    The intestinal epithelium normally provides a barrier function that prevents absorption of potentially harmful materials from the intestinal lumen. It has been postulated but never demonstrated that a cutaneous thermal injury will result in increased small-intestinal permeability. In a standardized 20% body surface area full-thickness scald injury, with polyethylene glycol 3350 and horseradish peroxidase used as permeability probes, small-intestinal permeability was examined regionally in an everted intestinal sac model. In the normal animals, the upper (proximal) and lower (distal) small intestine were less permeable to these probes than the middle segment. Within 6 hours after the injury, an increase in the mucosal uptake and transmural permeability was seen in all three small-intestinal segments; the most dramatic increase in permeability occurred in the ileum, p less than 0.01. The maximum increase in permeability was seen at 18 hours, and permeability was normal by 72 hours after the injury. This increase in intestinal permeability may represent a transient failure of the intestinal barrier function and may allow absorption of potentially toxic macromolecules from the intestinal lumen into the portal circulation early after thermal injury. Absorption of these macromolecules, such as endotoxin, may be potentially harmful by direct toxic actions or potentially helpful by activation of the immune system. PMID:2309150

  18. Increased Vascular permeability produced by human platelet granule cationic extract

    PubMed Central

    Nachman, Ralph L.; Weksler, Babette; Ferris, Barbara

    1970-01-01

    A cationic protein extract obtained from isolated human platelet granules increased vascular permeability in mouse and rabbit skin. The permeability-enhancing effect was not inhibited by soybean trypsin and pancreatic trypsin inhibitor, methylsergide maleate, carboxypeptidase B, and C[unk]1 inactivator. Permeability-enhancing activity was blocked by prior treatment of challenged animals with antihistamine. The nondializable relatively heat-stable cationic granule protein extract possessed potent mastocytolytic activity. The experiments described suggest that human platelets exert a permeability-enhancing effect by lysosomal release of cationic proteins which cause histamine release from adjacent tissue mast cells. Images PMID:4391559

  19. 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.

  20. Characterizing average permeability in oil and gas formations

    SciTech Connect

    Rollins, J.B. ); Holditch, S.A.; Lee, W.J. )

    1992-03-01

    This paper reports that permeability in a formation frequently follows a unimodal probability distribution. In many formations, particularly sedimentary ones, the permeability distribution is similar to the log-normal distribution. Theoretical considerations, field cases, and a reservoir simulation example show that the median, rather than the arithmetic mean, is the appropriate measure of central tendency or average value of the permeability distribution in a formation. Use of the correct estimate of average permeability is of particular importance in the classification of tight gas formations under statues in the 1978 Natural Gas Policy Act (NGPA).

  1. 21 CFR 876.5860 - High permeability hemodialysis system.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ..., hematocrit, urea, etc.). (3) The high permeability hemodialysis system accessories include, but are not..., hematocrit, and blood recirculation monitors). (b) Classification. Class II. The special controls for...

  2. 21 CFR 876.5860 - High permeability hemodialysis system.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ..., hematocrit, urea, etc.). (3) The high permeability hemodialysis system accessories include, but are not..., hematocrit, and blood recirculation monitors). (b) Classification. Class II. The special controls for...

  3. 21 CFR 876.5860 - High permeability hemodialysis system.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ..., hematocrit, urea, etc.). (3) The high permeability hemodialysis system accessories include, but are not..., hematocrit, and blood recirculation monitors). (b) Classification. Class II. The special controls for...

  4. 21 CFR 876.5860 - High permeability hemodialysis system.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ..., hematocrit, urea, etc.). (3) The high permeability hemodialysis system accessories include, but are not..., hematocrit, and blood recirculation monitors). (b) Classification. Class II. The special controls for...

  5. Composite binders for concrete with reduced permeability

    NASA Astrophysics Data System (ADS)

    Fediuk, R.; Yushin, A.

    2016-02-01

    Composite binder consisting of cement (55%), acid fly ash (40%) and limestone (5%) has been designed. It is obtained by co-milling to a specific surface of 550 kg/m2, it has an activity of 77.3 MPa and can produce a more dense cement stone structure. Integrated study revealed that the concrete on the composite binder basis provides an effective diffusion coefficient D. So we can conclude that the concrete layer protects buildings from toxic effects of expanded polystyrene. Low water absorption of the material (2.5% by weight) is due to the structure of its cement stone pore space. Besides lime powder prevents the penetration of moisture, reduces water saturation of the coverage that has a positive effect on useful life period. It also explains rather low water vapor permeability of the material - 0.021 mg/(m- hour-Pa).

  6. Signal Transduction to the Permeability Transition Pore

    PubMed Central

    Rasola, Andrea; Sciacovelli, Marco; Pantic, Boris; Bernardi, Paolo

    2010-01-01

    The permeability transition pore (PTP) is an inner mitochondrial membrane channel that has been thoroughly characterized functionally, yet remains an elusive molecular entity. The best characterized PTP-regulatory component, cyclophilin (CyP) D, is a matrix protein that favors pore opening. CyP inhibitors, CyPD null animals, and in situ PTP readouts have established the role of PTP as an effector mechanism of cell death, and the growing definition of PTP signaling mechanisms. This review briefly covers the functional features of the PTP and the role played by its dysregulation in disease pathogenesis. Recent progress on PTP modulation by kinase/phosphatase signal transduction is discussed, with specific emphasis on hexokinase and on the Akt-ERK-GSK3 axis, which might modulate the PTP through CyPD phosphorylation. PMID:20153328

  7. Osmotic flow through fully permeable nanochannels.

    PubMed

    Lee, C; Cottin-Bizonne, C; Biance, A-L; Joseph, P; Bocquet, L; Ybert, C

    2014-06-20

    Osmosis across membranes is intrinsically associated with the concept of semipermeability. Here, however, we demonstrate that osmotic flow can be generated by solute gradients across nonselective, fully permeable nanochannels. Using a fluorescence imaging technique, we are able to measure the water flow rate inside single nanochannels to an unprecedented sensitivity of femtoliters per minute flow rates. Our results indicate the onset of a convective liquid motion under salinity gradients, from the higher to lower electrolyte concentration, which is attributed to diffusio-osmotic transport. To our knowledge, this is the first experimental evidence and quantitative investigation of this subtle interfacially driven transport, which need to be accounted for in nanoscale dynamics. Finally, diffusio-osmotic transport under a neutral polymer gradient is also demonstrated. The experiments highlight the entropic depletion of polymers that occurs at the nanochannel surface, resulting in convective flow in the opposite direction to that seen for electrolytes. PMID:24996091

  8. Osmotic water permeability in glycoprotein containing liposomes.

    PubMed

    Neitchev, V Z; Kostadinov, A P

    1987-01-01

    The kinetics of osmotic water permeability in proteoliposomes containing alpha 1-acid glycoprotein was investigated by means of stopped-flow spectrophotometry. A biphasic time-course of scattered light with time was registered. The rate constants calculated from fits to an exponential function in the first phase were proportional to the final medium osmolarity. The apparent second order rate constants Kapp (Osm-1 sec-1) were determined at different glycoprotein concentrations in the original mixture for preparation of proteoliposomes. The value of Kapp at lipid:glycoprotein weight ratio = 1 was plotted in Arrhenius coordinates. The calculated activation energy for water permeation through the lipid bilayer suggests that eventual channel mechanism may be involved due to the presence of glycoprotein molecule in the liposomes. PMID:3431542

  9. Biomimetic Hybrid Nanocontainers with Selective Permeability.

    PubMed

    Messager, Lea; Burns, Jonathan R; Kim, Jungyeon; Cecchin, Denis; Hindley, James; Pyne, Alice L B; Gaitzsch, Jens; Battaglia, Giuseppe; Howorka, Stefan

    2016-09-01

    Chemistry plays a crucial role in creating synthetic analogues of biomacromolecular structures. Of particular scientific and technological interest are biomimetic vesicles that are inspired by natural membrane compartments and organelles but avoid their drawbacks, such as membrane instability and limited control over cargo transport across the boundaries. In this study, completely synthetic vesicles were developed from stable polymeric walls and easy-to-engineer membrane DNA nanopores. The hybrid nanocontainers feature selective permeability and permit the transport of organic molecules of 1.5 nm size. Larger enzymes (ca. 5 nm) can be encapsulated and retained within the vesicles yet remain catalytically active. The hybrid structures constitute a new type of enzymatic nanoreactor. The high tunability of the polymeric vesicles and DNA pores will be key in tailoring the nanocontainers for applications in drug delivery, bioimaging, biocatalysis, and cell mimicry. PMID:27560310

  10. Fluid permeability measurement system and method

    DOEpatents

    Hallman, Jr., Russell Louis; Renner, Michael John

    2008-02-05

    A system for measuring the permeance of a material. The permeability of the material may also be derived. The system provides a liquid or high concentration fluid bath on one side of a material test sample, and a gas flow across the opposing side of the material test sample. The mass flow rate of permeated fluid as a fraction of the combined mass flow rate of gas and permeated fluid is used to calculate the permeance of the material. The material test sample may be a sheet, a tube, or a solid shape. Operational test conditions may be varied, including concentration of the fluid, temperature of the fluid, strain profile of the material test sample, and differential pressure across the material test sample.

  11. Composite Crew Module (CCM) Permeability Characterization

    NASA Technical Reports Server (NTRS)

    Kirsch, Michael T.

    2013-01-01

    In January 2007, the NASA Administrator chartered the NASA Engineering and Safety Center (NESC) to form an Agency team to design and build a composite crew module in 18 months in order to gain hands-on experience in anticipation that future exploration systems may be made of composite materials. One of the conclusions from this Composite Crew Module Primary Structure assessment was that there was a lack of understanding regarding the ability for composite pressure shells to contain consumable gases, which posed a technical risk relative to the use of a metallic design. After the completion of the Composite Crew Module test program, the test article was used in a new program to assess the overall leakage/permeability and identify specific features associated with high leak rates. This document contains the outcome of the leakage assessment.

  12. Osmotic Flow through Fully Permeable Nanochannels

    NASA Astrophysics Data System (ADS)

    Lee, C.; Cottin-Bizonne, C.; Biance, A.-L.; Joseph, P.; Bocquet, L.; Ybert, C.

    2014-06-01

    Osmosis across membranes is intrinsically associated with the concept of semipermeability. Here, however, we demonstrate that osmotic flow can be generated by solute gradients across nonselective, fully permeable nanochannels. Using a fluorescence imaging technique, we are able to measure the water flow rate inside single nanochannels to an unprecedented sensitivity of femtoliters per minute flow rates. Our results indicate the onset of a convective liquid motion under salinity gradients, from the higher to lower electrolyte concentration, which is attributed to diffusio-osmotic transport. To our knowledge, this is the first experimental evidence and quantitative investigation of this subtle interfacially driven transport, which need to be accounted for in nanoscale dynamics. Finally, diffusio-osmotic transport under a neutral polymer gradient is also demonstrated. The experiments highlight the entropic depletion of polymers that occurs at the nanochannel surface, resulting in convective flow in the opposite direction to that seen for electrolytes.

  13. Gas permeable electrode for electrochemical system

    DOEpatents

    Ludwig, F.A.; Townsend, C.W.

    1989-09-12

    An electrode apparatus is described which is adapted for use in electrochemical systems having an anode compartment and a cathode compartment in which gas and ions are produced and consumed in the compartments during generation of electrical current. The electrode apparatus includes a membrane for separating the anode compartment from the cathode compartment wherein the membrane is permeable to both ions and gas. The cathode and anode for the assembly are provided on opposite sides of the membrane. During use of the membrane-electrode apparatus in electrochemical cells, the gas and ions generated at the cathode or anode migrate through the membrane to provide efficient transfer of gas and ions between the anode and cathode compartments. 3 figs.

  14. Turbulent structures and budgets behind permeable ribs

    SciTech Connect

    Panigrahi, P.K.; Schroeder, A.; Kompenhans, J.

    2008-02-15

    Different rib geometries are traditionally used to improve heat transfer and enhance mixing in different industrial applications, i.e. heat exchangers, cooling passages of gas turbine blades and fuel elements of nuclear reactors, etc. Permeable ribs have been proposed in literature for passive control of the reattaching flow past surface mounted ribs leading to superior performance. The flow past different surface mounted permeable rib geometries, i.e. solid, slit, split-slit and inclined split-slit ribs have been investigated in this study. Both two components and stereo particle image velocimetry (PIV) have been used in streamwise and cross stream planes to study the underlying flow structures. The detailed turbulent statistics, i.e. mean and rms velocity, higher order moments, quadrant decomposition of turbulent shear stress producing motions, skewness and components of the turbulent kinetic energy budgets have been compared for different rib geometries. Coherent structures are identified based on the invariant of velocity gradient tensor invariant and wavelet transform. The skewness results demonstrate the intermittency of quadrant motions. The reattachment length of the inclined split-slit rib is lowest among all rib geometries. The average Reynolds stresses and the production of turbulent kinetic energy are highest for the inclined split-slit rib. The pressure transport calculated as residual of the turbulent kinetic energy budget equation is highest for the inclined split-slit rib. This is attributed to the smaller reattachment length leading to greater adverse pressure gradient for the inclined split-slit rib. The quadrant motions, turbulent fluxes, skewness and kinetic energy budgets at post reattachment region compares well with that of flat plate turbulent boundary layer from hot wire measurements in literature. Overall, this study demonstrates the effectiveness of PIV technique for the detailed turbulent structures characterization of complex flows

  15. Back diffusion from thin low permeability zones.

    PubMed

    Yang, Minjune; Annable, Michael D; Jawitz, James W

    2015-01-01

    Aquitards can serve as long-term contaminant sources to aquifers when contaminant mass diffuses from the aquitard following aquifer source mass depletion. This study describes analytical and experimental approaches to understand reactive and nonreactive solute transport in a thin aquitard bounded by an adjacent aquifer. A series of well-controlled laboratory experiments were conducted in a two-dimensional flow chamber to quantify solute diffusion from a high-permeability sand into and subsequently out of kaolinite clay layers of vertical thickness 15 mm, 20 mm, and 60 mm. One-dimensional analytical solutions were developed for diffusion in a finite aquitard with mass exchange with an adjacent aquifer using the method of images. The analytical solutions showed very good agreement with measured breakthrough curves and aquitard concentration distributions measured in situ by light reflection visualization. Solutes with low retardation accumulated more stored mass with greater penetration distance in the aquitard compared to high-retardation solutes. However, because the duration of aquitard mass release was much longer, high-retardation solutes have a greater long-term back diffusion risk. The error associated with applying a semi-infinite domain analytical solution to a finite diffusion domain increases as a function of the system relative diffusion length scale, suggesting that the solutions using image sources should be applied in cases with rapid solute diffusion and/or thin clay layers. The solutions presented here can be extended to multilayer aquifer/low-permeability systems to assess the significance of back diffusion from thin layers. PMID:25478850

  16. Consolidation and permeability of salt in brine

    SciTech Connect

    Shor, A.J.; Baes, C.F. Jr.; Canonico, C.M.

    1981-07-01

    The consolidation and loss of permeability of salt crystal aggregates, important in assessing the effects of water in salt repositories, has been studied as a function of several variables. The kinetic behavior was similar to that often observed in sintering and suggested the following expression for the time dependence of the void fraction: phi(t) = phi(0) - (A/B)ln(1 + Bt/z(0)/sup 3/), where A and B are rate constants and z(0) is initial average particle size. With brine present, A and phi(0) varied linearly with stress. The initial void fraction was also dependent to some extent on the particle size distribution. The rate of consolidation was most rapid in brine and least rapid in the presence of only air as the fluid. A brine containing 5 m MgCl/sub 2/ showed an intermediate rate, presumably because of the greatly reduced solubility of NaCl. A substantial wall effect was indicated by an observed increase in the void fraction of consolidated columns with distance from the top where the stress was applied and by a dependence of consolidation rate on the column height and radius. The distance through which the stress fell by a factor of phi was estimated to change inversely as the fourth power of the column diameter. With increasing temperature (to 85/sup 0/C), consolidation proceeded somewhat more rapidly and the wall effect was reduced. The permeability of the columns dropped rapidly with consolidation, decreasing with about the sixth power of the void fraction. In general, extrapolation of the results to repository conditions confirms the self-sealing properties of bedded salt as a storage medium for radioactive waste.

  17. Hormonal regulation of hepatocyte tight junctional permeability

    SciTech Connect

    Lowe, P.J.; Miyai, K.; Steinbach, J.H.; Hardison, W.G.M. Univ. of California, San Diego )

    1988-10-01

    The authors have investigated the effects of hormones on the permeability of the hepatocyte tight junction to two probes, ({sup 14}C)sucrose and horseradish peroxidase, using one-pass perfused rat livers. Using a single injection of horseradish peroxidase the authors have demonstrated that this probe can enter bile by two pathways that are kinetically distinct, a fast pathway, which corresponds to the passage of the probe through the hepatocyte tight junctions, and a slow pathway, which corresponds to the transcytotic entry into bile. The passage of horseradish peroxidase through the hepatocyte tight junctions was confirmed by electron microscopic histochemistry. Vasopressin, epinephrine, and angiotensin II, hormones that act in the hepatocyte through the intracellular mediators calcium, the inositol polyphosphates, and diacylglycerol, increased the bile-to-perfusion fluid ratio of ({sup 14}C)sucrose and the rapid entry of horseradish peroxidase into bile, indicating that the permeability of the tight junctions to these probes was increased. The effect of these hormones was dose dependent and in the cases of angiotensin II and epinephrine was inhibited by the specific inhibitors (Sar{sup 1},Thr{sup 8})angiotensin II and prazosin, respectively. Dibutyryl adenosine 3{prime},5{prime}-cyclic monophosphate did not affect the ({sup 14}C)sucrose bile-to-perfusion fluid ratio or the fast entry of horseradish peroxidase into bile. These results suggest that the hepatocyte tight junction can no longer be considered a static system of pores separating blood from bile. It is rather a dynamic barrier potentially capable of influencing the composition of the bile.

  18. Turbulent Hyporheic Exchange in Permeable Sediments

    NASA Astrophysics Data System (ADS)

    Roche, K. R.; Aubeneau, A. F.; Li, A.; Packman, A. I.

    2015-12-01

    Solute delivery from the water column into a streambed strongly influences metabolism in rivers. Current hydrological models simplify surface-subsurface (hyporheic) exchange by treating each domain separately, constraining turbulent flows to the water column. Studies have shown, however, that turbulence penetrates into permeable sediments. Evidence is lacking for how this highly coupled flow regime influences hyporheic exchange. We characterized the dynamics of turbulent exchange between surface and porewaters in a 2.5 m recirculating flume. The channel was packed with 3.8 cm PVC spheres to form a coarse gravel bed, with a total depth of 21 cm. We implanted microsensors onto an array of spheres to measure in situsalt concentrations within the streambed. Water was recirculated in the channel, and concentrated salt solution was continuously injected upstream of the sensor array. We observed solute exchange increased with free-stream Reynolds number and decreased with depth in the sediment bed. Mass of injected solute remaining in the bed decreased rapidly in all cases, with only 10-30% of mass recovered 50 cm downstream of the injection point at Re = 25,000. We observed high-frequency (1-10 Hz) concentration fluctuations at bed depths of at least 4.75 cm, and sporadic low-frequency fluctuations at depths of 12.5 cm. Spectral analysis revealed increased filtering of high frequencies with depth. We used particle-tracking simulations to fit depth-dependent turbulent diffusion profiles to experimental results. These results demonstrate that free-stream turbulence impacts hyporheic mixing deep into permeable streambeds, and mixing is strongly influenced by the coupled surface-subsurface flow field.

  19. Parallel artificial membrane permeability assay for blood-brain permeability determination of illicit drugs and synthetic analogues.

    PubMed

    Clemons, Kristina; Kretsch, Amanda; Verbeck, Guido

    2014-09-01

    With the number of designer drugs on the streets rampantly on the rise, it's becoming more and more important to be able to rapidly characterize them in a biologically relevant way. Using a parallel artificial membrane permeability assay (PAMPA) to assess the blood brain barrier permeability has shown to be a high throughput way to compare new drugs with currently controlled substances via their effective permeability values. This combined with direct infusion electrospray ionization-mass spectrometry creates a rapid technique for characterization of new designer drugs. PAMPA has successfully determined the effective permeabilities of cocaine, methamphetamine, heroin, MDMA, and several tryptamine derivatives. PMID:25278197

  20. Hydraulic Permeability of Resorcinol-Formaldehyde Resin

    SciTech Connect

    Taylor, Paul Allen

    2010-01-01

    An ion exchange process using spherical resorcinol-formaldehyde (RF) resin is the baseline process for removing cesium from the dissolved salt solution in the high-level waste tanks at the Hanford Site, using large scale columns as part of the Waste Treatment Plant (WTP). The RF resin is also being evaluated for use in the proposed small column ion exchange (SCIX) system, which is an alternative treatment option at Hanford and at the Savannah River Site (SRS). A recirculating test loop with a small ion exchange column was used to measure the effect of oxygen uptake and radiation exposure on the permeability of a packed bed of the RF resin. The lab-scale column was designed to be prototypic of the proposed Hanford columns at the WTP. Although the test equipment was designed to model the Hanford ion exchange columns, the data on changes in the hydraulic permeability of the resin will also be valuable for determining potential pressure drops through the proposed SCIX system. The superficial fluid velocity in the lab-scale test (3.4-5.7 cm/s) was much higher than is planned for the full-scale Hanford columns to generate the maximum pressure drop expected in those columns (9.7 psig). The frictional drag from this high velocity produced forces on the resin in the lab-scale tests that matched the design basis of the full-scale Hanford column. Any changes in the resin caused by the radiation exposure and oxygen uptake were monitored by measuring the pressure drop through the lab-scale column and the physical properties of the resin. Three hydraulic test runs were completed, the first using fresh RF resin at 25 C, the second using irradiated resin at 25 C, and the third using irradiated resin at 45 C. A Hanford AP-101 simulant solution was recirculated through a test column containing 500 mL of Na-form RF resin. Known amounts of oxygen were introduced into the primary recirculation loop by saturating measured volumes of the simulant solution with oxygen and reintroducing

  1. Paracellular and transcellular pathways facilitate insulin permeability in rat gut.

    PubMed

    Lane, Majella E; Corrigan, Owen I

    2006-02-01

    The aim of this study was to conduct a systematic investigation of the absorption of insulin in the rat intestine in the presence of permeation enhancers and protease inhibitors. An in-situ perfused rat gut model was used for the co-perfusion of insulin and PEG 4000 in the presence or absence of bile salts, bile salt:fatty acid surfactant systems and protease inhibitors. Perfusion experiments were conducted for 180 min with perfusate and blood collection at regular intervals. Permeability coefficients for insulin were calculated from plasma insulin and PEG 4000 permeability coefficients were calculated from lumenal disappearance data. In the absence of enzyme inhibitors, insulin permeability was consistently lower than PEG 4000, but increased in proportion to PEG 4000 permeability. Large increases in insulin permeability were obtained for mixed micellar systems and protease inhibitors. In the presence of protease inhibitors and simple micelle systems, PEG 4000 permeability was three-fold greater than insulin permeability. In the presence of absorption enhancers, PEG 4000 permeability increased up to a maximum value of 3.63 x 10(-6)cm s(-1), a value five-fold less than that of the estimated aqueous boundary layer permeability for PEG 4000. This suggests that PEG 4000 permeability is primarily membrane controlled. Insulin permeability is enhanced to a maximum value of 9.17 x 10(-6)cm s(-1), suggesting that paracellular transport routes do not account exclusively for insulin permeation across the intestinal epithelium. The results add support to suggestions that routes other than the paracellular route may contribute to insulin absorption in rat gut. PMID:16451757

  2. Hepatic Injury in Nonalcoholic Steatohepatitis Contributes to Altered Intestinal Permeability

    PubMed Central

    Luther, Jay; Garber, John J.; Khalili, Hamed; Dave, Maneesh; Bale, Shyam Sundhar; Jindal, Rohit; Motola, Daniel L.; Luther, Sanjana; Bohr, Stefan; Jeoung, Soung Won; Deshpande, Vikram; Singh, Gurminder; Turner, Jerrold R.; Yarmush, Martin L.; Chung, Raymond T.; Patel, Suraj J.

    2015-01-01

    BACKGROUND & AIMS Emerging data suggest that changes in intestinal permeability and increased gut microbial translocation contribute to the inflammatory pathway involved in nonalcoholic steatohepatitis (NASH) development. Numerous studies have investigated the association between increased intestinal permeability and NASH. Our meta-analysis of this association investigates the underlying mechanism. METHODS A meta-analysis was performed to compare the rates of increased intestinal permeability in patients with NASH and healthy controls. To further address the underlying mechanism of action, we studied changes in intestinal permeability in a diet-induced (methionine-and-choline-deficient; MCD) murine model of NASH. In vitro studies were also performed to investigate the effect of MCD culture medium at the cellular level on hepatocytes, Kupffer cells, and intestinal epithelial cells. RESULTS Nonalcoholic fatty liver disease (NAFLD) patients, and in particular those with NASH, are more likely to have increased intestinal permeability compared with healthy controls. We correlate this clinical observation with in vivo data showing mice fed an MCD diet develop intestinal permeability changes after an initial phase of liver injury and tumor necrosis factor-α (TNFα) induction. In vitro studies reveal that MCD medium induces hepatic injury and TNFα production yet has no direct effect on intestinal epithelial cells. Although these data suggest a role for hepatic TNFα in altering intestinal permeability, we found that mice genetically resistant to TNFα-myosin light chain kinase (MLCK)–induced intestinal permeability changes fed an MCD diet still develop increased permeability and liver injury. CONCLUSIONS Our clinical and experimental results strengthen the association between intestinal permeability increases and NASH and also suggest that an early phase of hepatic injury and inflammation contributes to altered intestinal permeability in a fashion independent of TNF

  3. Permeability evolution in quartz fault gouges under hydrothermal conditions

    NASA Astrophysics Data System (ADS)

    Giger, Silvio B.; Tenthorey, Eric; Cox, Stephen F.; Fitz Gerald, John D.

    2007-07-01

    The permeability (k) of fine-grained quartz aggregates were measured in situ during hot pressing (HPing) experiments to explore the evolution of fluid transport properties of fault zones during the interseismic period. Experiments were conducted at temperatures of 150°C and between 700 and 850°C, with confining and pore water pressures of 250 and 150 MPa, respectively. Significant permeability reduction was observed between 700 and 850°C, with permeability reduction rates (r = (1/t) ln (kto/kt)), ranging from approximately 6 × 10-5 s-1 at 700°C to a maximum of approximately 7.4 × 10-4 s-1 at 850°C. Permeability decreased exponentially with time, and the permeability reduction rate increased with increasing temperature, increasing differential stress, and decreasing grain size. Analysis of the permeability-porosity relationships indicates that permeability in the simulated gouge at high temperature shuts off at a critical porosity of 0.045 ± 0.004. The presence of microstructures, such as grain interpenetration, grain shape truncation, arrays of fluid inclusions, and development of quartz overgrowths on grains, indicate that k reduction was controlled by dissolution-precipitation creep processes. Extrapolation of the permeability reduction rates, measured in this study, to temperatures typical of the continental seismogenic regime highlights the strongly time-dependent nature of permeability in natural fault wear products at depths of nucleation of major earthquakes. Within the recurrence time of large earthquakes, quartz-rich fault zones in the fluid-active midcrustal to lower continental crustal regimes can evolve from high-permeability conduits to low-permeability seals. Episodic changes in the fluid transport properties of faults during the interseismic period are likely to impact on the pore pressure evolution of fault wear products.

  4. Porosity and permeability evolution of clay faults: in situ experiments

    NASA Astrophysics Data System (ADS)

    Henry, P.; Guglielmi, Y.; Seguy, S.; Lefevre, M.; Ghani, I.; Gent, G.; Castilla, R.; Gout, C.; Dick, P.; Nussbaum, C.; Durand, J.

    2015-12-01

    Fault models associating low permeability cores with high permeability damage zones are widely accepted, however, constitutive laws relating permeability with fault structure, stress, and strain remain poorly constrained. We here present preliminary results of hydromechanical experiments performed at the 10 m scale in fault zones in Toarcian and Aalenian black shale formations. Intact formations have a very low permeability (10-19 to 10-22 m2). One case (in IRSN's Tournemire Underground Research Laboratory) displays a porosity increase in and around the fault core and abundant veins and calcite cemented small faults in the damage zone. The other case (Mont Terri Swisstopo Underground Research Laboratory) displays a porosity decrease in the fault core zone and few veins. However, under the present stress state, the static permeability of the fractured zones at both locations is higher than that of the intact formation by up to 3 orders of magnitude. During borehole pressurization tests three regimes of permeability variations are observed. (1) Fracture permeability first increases progressively as a function of fluid pressure (2) When a threshold is reached, permeability further increases by 100 or more, but strain as well as permeability variations remain in most part reversible. (3) When a steady pressure is maintained in the injection borehole (from 20 minutes to several days) flow rate tends to decrease with time. These results show that high transient permeability may locally occur in a fault zone under conditions when most of the deformation is reversible, opening the possibility of transient fluid migration decoupled from slip along faults that are not favorably oriented. However, during one test, more than 1 mm of irreversible slip occurred along one of the main interfaces, associated with a sudden increase in flow rate (from 11 to more than 40 l/min). This suggests that when slip occurs, it could result in permeability variations that may remain difficult

  5. Further investigations of why gels reduce water permeability more than oil permeability

    SciTech Connect

    Liang, J.T.; Seright, R.S.

    1997-11-01

    In this paper, the authors investigate why some gels can reduce the permeability to water much more than to oil. This property is critical to the success of chemical-based water-shutoff treatments in production wells if hydrocarbon-productive zones cannot be protected during placement. The authors first briefly review previous findings and the validity of several possible explanations for this disproportionate permeability reduction. Next, they describe experiments that test the validity of a promising mechanism--the segregated pathway theory. This theory speculates that on a microscopic scale, aqueous gelants follow water pathways more than oil pathways. Experimental results in cores support this mechanism for oil-based gels, but not for water-based gels. They also explore another interesting mechanism that involves a balance between capillary and elastic forces. Results from experiments support this mechanism for flow in tubes and micromodels, but not in porous rock. Other mechanisms are also discussed.

  6. Determination of Coal Permeability Using Pressure Transient Methods

    SciTech Connect

    McLendon, T.R.; Siriwardane, H.; Haljasmaa, I.V.; Bromhal, G.S.; Soong, Y.; Irdi, G.A.

    2007-05-01

    Coalbed methane is a significant natural resource in the Appalachian region. It is believed that coalbed methane production can be enhanced by injection of carbon dioxide into coalbeds. However, the influence of carbon dioxide injection on coal permeability is not yet well understood. Competitive sorption of carbon dioxide and methane gases onto coal is a known process. Laboratory experiments and limited field experience indicate that coal will swell during sorption of a gas and shrink during desorption of a gas. The swelling and shrinkage may change the permeability of the coal. In this study, the permeability of coal was determined by using carbon dioxide as the flowing fluid. Coal samples with different dimensions were prepared for laboratory permeability tests. Carbon dioxide was injected into the coal and the permeability was determined by using pressure transient methods. The confining pressure was variedto cover a wide range of depths. The permeability was also determined as a function of exposure time of carbon dioxide while the confining stress was kept constant. CT scans were taken before and after the introduction of carbon dioxide. Results show that the porosity and permeability of the coal matrix was very low. The paper presents experimental data and theoretical aspects of the flow of carbon dioxide through a coal sample during pressure transient tests. The suitability of the pressure transient methods for determining permeability of coal during carbon dioxide injection is discussed in the paper.

  7. The structure of turbulence overlying impermeable and permeable rough walls

    NASA Astrophysics Data System (ADS)

    Kim, T.; Blois, G.; Best, J.; Christensen, K. T.

    2014-11-01

    Turbulent flow overlying complex topographies, both impermeable and permeable, occur across a broad range of scales in both natural and engineering environments. Permeability of the wall introduces a higher degree of both structural and conceptual complexity, with previous studies suggesting that interactions between the turbulent free flow and pore flow occur along the permeable interface and play a defining role in momentum exchange across the interface. Here we employ a Refractive-Index-Matching (RIM) technique in order to access the flow across the permeable interface with the particle image velocimetry (PIV) method, resulting in unimpeded optical access to the fluid flow at and within a permeable bed. Cubic-packed hemispheres are studied in both impermeable and permeable configurations, with models cast by an acrylic resin whose refractive index matched that of the working fluid (aqueous sodium iodide). The statistical and structural features of the flow in the near-wall region of the impermeable case and the interfacial region of the permeable case are compared to understand the role of permeability in driving momentum exchange processes as a function of Reynolds number. Comparisons to recent numerical simulations are also made.

  8. Permeable Pavement Research at the Edison Environmental Center

    EPA Science Inventory

    There are few detailed studies of full-scale, replicated, actively-used permeable pavement systems. Practitioners need additional studies of permeable pavement systems in its intended application (parking lot, roadway, etc.) across a range of climatic events, daily usage conditio...

  9. Predicting permeability from porosity using artificial neural networks

    SciTech Connect

    Rogers, S.J.; Fang, J.H.; Chen, H.C. Kopaska-Merkel, D.C.

    1995-12-01

    Permeability values in a borehole are predicted by an artificial neural network from the porosity values at the same depths. THe network used in this study employs an architecture called backpropagation that is good at making predictions. The traditional approach for permeability prediction is regression analysis, the relationship between porosity and permeability is assumed to be known. In reality, the functional form of this relationship, i.e., the model equation, is unknown. In contrast, the neural-network approach assumes no functional relationship. Six wells from Big Escambia Creek (Jurassic Smackover carbonate) field in southern Alabama were used to test predicting permeability from porosity using a neural network. Porosity and spatial data alone were used to predict permeability because these data are readily available from any hydrocarbon field. Three scenarios were performed; in each one, a subset of the six wells was used for a training set, one well for calibration, and one or two wells were used for prediction. For each scenario, simple linear regression was also used to predict permeability from porosity. The neural net predicted permeability much better than did regression in one scenario; in the other two scenarios the two methods performed equally well. The neural net predicted permeability accurately using minimal data, but other kinds of information (e.g., log- or core-derived lithologic information) are easily incorporated if available. In addition, compartmentalization of carbonate reservoirs may be recognizable by this approach.

  10. PREFERENTIAL RADON TRANSPORT THROUGH HIGHLY PERMEABLE CHANNELS IN SOILS

    EPA Science Inventory

    The paper discusses preferential radon transport through highly permeable channels in soils. Indoor radon levels (that can pose a serious health risk) can be dramatically increased by air that is drawn into buildings through pipe penetrations that connect to permeable channels in...

  11. Permeability of hydrogen isotopes through nickel-based alloys

    SciTech Connect

    Edge, E.M.; Mitchell, D.J.

    1983-04-01

    Permeabilities and diffusivities of deuterium in several nickel-based alloys were measured in this investigation. Measurements were made by the gas-phase breakthrough technique in the temperature range 200 to 450/sup 0/C with applied pressures ranging from 1 to 100 kPa. The results were extrapolated to predict the permeabilities (K) of the alloys at room temperature. The alloy with the smallest deuterium permeability is Carpenter 49, for which K = 4.3 x 10/sup -18/ mol s/sup -1/ m/sup -1/ Pa/sup -//sup 1/2/ at 22/sup 0/C. The permeability of deuterium in Kovar or Ceramvar is about 80% greater than that for Carpenter 49. Premeabilities of Inconel 625, Inconel 718, Inconel 750 and Monel K-500 are all equal to about 5 x 10/sup -17/ mol m/sup -1/ s/sup -1/ Pa/sup -//sup 1/2/ at 22/sup 0/C. The validity (from a statistical standpoint) of the extrapolation of the permeabilities to room temperature is considered in detail. Published permeabilities of stainless steels and nickel-iron alloys are also reviewed. The greatest differences in permeabilities among the nickel-based alloys appear to be associated with the tendency for some alloys to form protective oxide layers. Permeabilities of deuterium through laminates containing copper are smaller than for any of the iron-nickel alloys.

  12. Nitrogen Transformations in Three Types of Permeable Pavement

    EPA Science Inventory

    In 2009, USEPA constructed a 0.4-ha (1-ac) parking lot at the Edison Environmental Center in Edison, NJ, that incorporated three different permeable pavement types - permeable interlocking concrete pavers (PICP), pervious concrete (PC), and porous asphalt (PA). The driving lanes...

  13. 21 CFR 886.5916 - Rigid gas permeable contact lens.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Rigid gas permeable contact lens. 886.5916 Section 886.5916 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES... lens. (a) Identification. A rigid gas permeable contact lens is a device intended to be worn...

  14. 21 CFR 886.5916 - Rigid gas permeable contact lens.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Rigid gas permeable contact lens. 886.5916 Section 886.5916 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES... lens. (a) Identification. A rigid gas permeable contact lens is a device intended to be worn...

  15. 21 CFR 886.5916 - Rigid gas permeable contact lens.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Rigid gas permeable contact lens. 886.5916 Section 886.5916 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES... lens. (a) Identification. A rigid gas permeable contact lens is a device intended to be worn...

  16. 21 CFR 886.5916 - Rigid gas permeable contact lens.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Rigid gas permeable contact lens. 886.5916 Section 886.5916 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES... lens. (a) Identification. A rigid gas permeable contact lens is a device intended to be worn...

  17. 21 CFR 886.5916 - Rigid gas permeable contact lens.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Rigid gas permeable contact lens. 886.5916 Section 886.5916 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES... lens. (a) Identification. A rigid gas permeable contact lens is a device intended to be worn...

  18. Nanochannel flow past permeable walls via molecular dynamics

    NASA Astrophysics Data System (ADS)

    Xie, Jian-Fei; Cao, Bing-Yang

    2016-07-01

    The nanochannel flow past permeable walls with nanopores is investigated by molecular dynamics (MD) simulations, including the density distribution, velocity field, molecular penetration mechanism and surface friction coefficient. A low density distribution has been found at the gas-wall interface demonstrating the low pressure region. In addition, there exists a jump of the gas density on the permeable surface, which indicates the discontinuity of the density distribution across the permeable surface. On the other hand, the nanoscale vortices are observed in nanopores of the permeable wall, and the reduced mass flux of the flow in nanopores results in a shifted hydrodynamic boundary above the permeable surface. Particularly the slip length of the gas flow on the permeable surface is pronounced a non-linear function of the molecular mean free path, which produces a large value of the tangential momentum accommodation coefficient (TMAC) and a big portion of the diffusive refection. Moreover, the gas-gas interaction and multi-collision among gas molecules may take place in nanopores, which contribute to large values of TMAC. Consequently the boundary friction coefficient on the permeable surface is increased because of the energy dissipation consumed by the nanoscale vortices in nanopores. The molecular boundary condition provides us with a new picture of the nanochannel flow past the permeable wall with nanopores.

  19. Hydrogen-permeable composite metal membrane and uses thereof

    DOEpatents

    Edlund, D.J.; Friesen, D.T.

    1993-06-08

    Various hydrogen production and hydrogen sulfide decomposition processes are disclosed that utilize composite metal membranes that contain an intermetallic diffusion barrier separating a hydrogen-permeable base metal and a hydrogen-permeable coating metal. The barrier is a thermally stable inorganic proton conductor.

  20. Determination of hydrogen permeability in uncoated and coated superalloys

    NASA Technical Reports Server (NTRS)

    Bhattacharyya, S.; Vesely, E. J., Jr.; Hill, V. L.

    1981-01-01

    Hydrogen permeability, diffusivity, and solubility data were obtained for eight wrought and cast high temperature alloys over the range 650 to 815 C. Data were obtained for both uncoated alloys and wrought alloys coated with four commercially available coatings. Activation energies for permeability, diffusivity and solubility were calculated.

  1. The Permeability of Territorial Space: Some Evidence from Military Warfare.

    ERIC Educational Resources Information Center

    Khoury, Robert M.

    1984-01-01

    Investigated military invasions (N=58) of the territorial boundaries of nation-states, and attempted to document empirically the territorial space permeability function. Results showed that the function relating intrusion to discomfort was found to be conspicuously similar to the personal space permeability function described by Hayduk (1981).…

  2. Selective permeability of PVA membranes. I - Radiation-crosslinked membranes

    NASA Technical Reports Server (NTRS)

    Katz, M. G.; Wydeven, T., Jr.

    1981-01-01

    The water and salt transport properties of ionizing radiation crosslinked poly(vinyl alcohol) (PVA) membranes were investigated. The studied membranes showed high permeabilities and low selectivities for both water and salt. The results were found to be in accord with a modified solution-diffusion model for transport across the membranes, in which pressure-dependent permeability coefficients are employed.

  3. Mapping permeability over the surface of the Earth

    USGS Publications Warehouse

    Gleeson, Tom; Smith, Leslie; Moosdorf, Nils; Hartmann, Jens; Durr, Hans H.; Manning, Andrew H.; van Beek, Ludovicus P. H.; Jellinek, A. Mark

    2011-01-01

    Permeability, the ease of fluid flow through porous rocks and soils, is a fundamental but often poorly quantified component in the analysis of regional-scale water fluxes. Permeability is difficult to quantify because it varies over more than 13 orders of magnitude and is heterogeneous and dependent on flow direction. Indeed, at the regional scale, maps of permeability only exist for soil to depths of 1-2 m. Here we use an extensive compilation of results from hydrogeologic models to show that regional-scale (>5 km) permeability of consolidated and unconsolidated geologic units below soil horizons (hydrolithologies) can be characterized in a statistically meaningful way. The representative permeabilities of these hydrolithologies are used to map the distribution of near-surface (on the order of 100 m depth) permeability globally and over North America. The distribution of each hydrolithology is generally scale independent. The near-surface mean permeability is of the order of -5 x 10-14 m2. The results provide the first global picture of near-surface permeability and will be of particular value for evaluating global water resources and modeling the influence of climate-surface-subsurface interactions on global climate change.

  4. Mapping permeability over the surface of the Earth

    USGS Publications Warehouse

    Gleeson, T.; Smith, L.; Moosdorf, N.; Hartmann, J.; Durr, H.H.; Manning, A.H.; Van Beek, L. P. H.; Jellinek, A. Mark

    2011-01-01

    Permeability, the ease of fluid flow through porous rocks and soils, is a fundamental but often poorly quantified component in the analysis of regional-scale water fluxes. Permeability is difficult to quantify because it varies over more than 13 orders of magnitude and is heterogeneous and dependent on flow direction. Indeed, at the regional scale, maps of permeability only exist for soil to depths of 1-2 m. Here we use an extensive compilation of results from hydrogeologic models to show that regional-scale (>5 km) permeability of consolidated and unconsolidated geologic units below soil horizons (hydrolithologies) can be characterized in a statistically meaningful way. The representative permeabilities of these hydrolithologies are used to map the distribution of near-surface (on the order of 100 m depth) permeability globally and over North America. The distribution of each hydrolithology is generally scale independent. The near-surface mean permeability is of the order of ???5 ?? 10-14 m2. The results provide the first global picture of near-surface permeability and will be of particular value for evaluating global water resources and modeling the influence of climate-surface-subsurface interactions on global climate change. Copyright ?? 2011 by the American Geophysical Union.

  5. Permeable Textual Discussion in Tracked Language Arts Classrooms

    ERIC Educational Resources Information Center

    Gritter, Kristine

    2012-01-01

    Permeable textual discussion occurs when the unofficial texts and discursive practices and personal histories that are already recognized and valued in students' cultures are scaffolds to academically sanctioned literacies. Ideally, permeable textual discussions are safe havens where students' identities (racial, gender, world views) are…

  6. Unsaturated and Saturated Permeabilities of Fiber Reinforcement: Critics and Suggestions

    NASA Astrophysics Data System (ADS)

    Park, Chung Hae; Krawczak, Patricia

    2015-04-01

    In general, permeability measurement results show a strong scattering according to the measurement method, the type of test fluid and the fluid injection condition, even though permeability is regarded as a unique property of porous medium. In particular, the discrepancy between the unsaturated and saturated permeabilities for the same fabric has been widely reported. In the literature, relative permeability has been adopted to model the unsaturated flow. This approach has some limits in the modeling of double-scale porosity medium. We address this issue of permeability measurement by rigorously examining the mass conservation condition. Finally, we identify that the pressure gradient is non-linear with positive curvature in the unsaturated flow and a misinterpretation of pressure gradient is the main reason for the difference between the saturated and unsaturated permeabilities of the same fiber reinforcement. We propose to use a fixed value of permeability and to modify the mass conservation equation if there are air voids which are entrapped inside the fiber tow. Finally, we also suggest some guidelines and future perspectives to obtain more consistent permeability measurement results.

  7. Selective Permeability of PVA Membranes. I: Radiation-Crosslinked Membranes

    NASA Technical Reports Server (NTRS)

    Katz, Moshe G.; Wydeven, Theodore, Jr.

    1981-01-01

    The water and salt transport properties of ionizing radiation crosslinked poly(vinyl alcohol) (PVA) membranes were investigated. The studied membranes showed high permeabilities and low selectivities for both water and salt. The results were found to be in accord with a modified solution-diffusion model for transport across the membranes, in which pressure-dependent permeability coefficients are employed.

  8. Modeling the Hydrologic Processes of a Permeable Pavement System

    EPA Science Inventory

    A permeable pavement system can capture stormwater to reduce runoff volume and flow rate, improve onsite groundwater recharge, and enhance pollutant controls within the site. A new unit process model for evaluating the hydrologic performance of a permeable pavement system has be...

  9. Permeability of mono- and bi-dispersed porous media

    NASA Astrophysics Data System (ADS)

    Byon, C.; Kim, S. J.

    2013-04-01

    In this study, the permeability of mono- and bi-dispersed porous media is considered. The effects of the particle size distribution and the packing structure of particles on the permeability are investigated experimentally and analytically. Both experimental and analytic results suggest that the particlesize distribution is close to the log-normal distribution, and the permeability of the mono-dispersed porous media quasi-linearly decreases as the range of the particle size distribution increases. On the other hand, the effect of packing structure of particles on the permeability is shown to be negligible.The permeability of the bidispersed porous media quasi-linearly decreases as the range of cluster size increases, and nearly independent of the particle size distribution. The present model is valid over the range of parameters typically found in heat transfer applications.

  10. Effect of dengue virus-induced cytotoxin on capillary permeability.

    PubMed Central

    Dhawan, R.; Khanna, M.; Chaturvedi, U. C.; Mathur, A.

    1990-01-01

    Capillary permeability is increased in cases of dengue haemorrhagic fever (DHF) and dengue shock syndrome (DSS) but its genesis is not known. Dengue type 2 virus (DV) induces production of a cytokine (CF2) by mouse macrophages. The present study was undertaken to investigate the effect of CF2 on capillary permeability. It was observed that intraperitoneal inoculation of CF2 in mice increased the capillary permeability in a dose-dependent manner, as shown by leakage of intravenously injected radioactive iodine (125I) or Evan's blue dye in the peritoneal cavity. Peak leakage occurred at 30 min and the vascular integrity was restored by 1-2 h. The increase in capillary permeability was abrogated by pretreatment of mice with avil (H1 receptor blocker) but not by ranitidine (H2 receptor blocker). The findings thus show that DV-induced CF2 increases the capillary permeability via release of histamine. PMID:2310617

  11. EPSA: A Novel Supercritical Fluid Chromatography Technique Enabling the Design of Permeable Cyclic Peptides

    PubMed Central

    2014-01-01

    Most peptides are generally insufficiently permeable to be used as oral drugs. Designing peptides with improved permeability without reliable permeability monitoring is a challenge. We have developed a supercritical fluid chromatography technique for peptides, termed EPSA, which is shown here to enable improved permeability design. Through assessing the exposed polarity of a peptide, this technique can be used as a permeability surrogate. PMID:25313332

  12. Impact of permeability on seismoelectric transfer function of P waves

    NASA Astrophysics Data System (ADS)

    Holzhauer, J.; Bordes, C.; Oppermann, F.; Brito, D.; Yaramanci, U.

    2012-04-01

    Recent developments in the understanding of seismoelectrics have shown its potential relevance for porous media characterization with particular focus on permeability estimations. According to promising theoretical and numerical studies, permeability should influence the seismoelectric transfer function at higher frequencies. The dynamic seismoelectric transfer function E(ω)/ ü(ω), where E relates to the coseismic electric field induced by the seismic particle acceleration ü, is expected to increase with increasing permeabilities when crossing the Biot transition frequency. Still, only few experiments have been developed on that matter so far. To address the transfer function dependence on permeability, we adapted a column experiment to comply with steady-state permeability estimations. These observations were run in-situ, during the fluid-balancing phase prior to seismoelectric measurements. The 50 cm-long column had previously been carefully filled with perfectly rounded glass beads. The use of sorted glass beads is expected to achieve similar porosities reproducible throughout the experiment, opposed to varying permeabilities depending on the introduced particle size. The acoustic source delivered compressional waves with an optimal effect limited to the [1-3] kHz frequency range. These limitations are due to strong seismic attenuation in uncompacted porous media on one side, and to the dilemma of observing propagation in downsized laboratory setup on the other. First results validated the experimental protocol in terms of porosity/permeability independence: for particle size varying between 100 μm and 500 μm, permeability varied by a factor 20, with a maximum by 5.10-11 m2, while porosity remained by 39 ± 2 % during the whole experiment. Further investigations are being led regarding the normalised transfer function, corrected for both the fluid conductivity and the seismic energy. For that purpose, we compare the dependence of our measured transfer

  13. Predicting skin permeability from complex chemical mixtures

    SciTech Connect

    Riviere, Jim E. . E-mail: Jim_Riviere@ncsu.edu; Brooks, James D.

    2005-10-15

    Occupational and environmental exposure to topical chemicals is usually in the form of complex chemical mixtures, yet risk assessment is based on experimentally derived data from individual chemical exposures from a single, usually aqueous vehicle, or from computed physiochemical properties. We present an approach using hybrid quantitative structure permeation relationships (QSPeR) models where absorption through porcine skin flow-through diffusion cells is well predicted using a QSPeR model describing the individual penetrants, coupled with a mixture factor (MF) that accounts for physicochemical properties of the vehicle/mixture components. The baseline equation is log k {sub p} = c + mMF + a{sigma}{alpha} {sub 2} {sup H} + b{sigma}{beta} {sub 2} {sup H} + s{pi} {sub 2} {sup H} + rR {sub 2} + vV {sub x} where {sigma}{alpha} {sub 2} {sup H} is the hydrogen-bond donor acidity, {sigma}{beta} {sub 2} {sup H} is the hydrogen-bond acceptor basicity, {pi} {sub 2} {sup H} is the dipolarity/polarizability, R {sub 2} represents the excess molar refractivity, and V {sub x} is the McGowan volume of the penetrants of interest; c, m, a, b, s, r, and v are strength coefficients coupling these descriptors to skin permeability (k {sub p}) of 12 penetrants (atrazine, chlorpyrifos, ethylparathion, fenthion, methylparathion, nonylphenol, {rho}-nitrophenol, pentachlorophenol, phenol, propazine, simazine, and triazine) in 24 mixtures. Mixtures consisted of full factorial combinations of vehicles (water, ethanol, propylene glycol) and additives (sodium lauryl sulfate, methyl nicotinate). An additional set of 4 penetrants (DEET, SDS, permethrin, ricinoleic acid) in different mixtures were included to assess applicability of this approach. This resulted in a dataset of 16 compounds administered in 344 treatment combinations. Across all exposures with no MF, R{sup 2} for absorption was 0.62. With the MF, correlations increased up to 0.78. Parameters correlated to the MF include refractive

  14. Electromagnetic imaging of lithosphere permeable zones

    NASA Astrophysics Data System (ADS)

    Litvinova, Tamara; Petrova Petrova, Alevtina; Petrishchev Petrishchev, Maxim

    2014-05-01

    By way of strong minima of magnetic anomalies studies we are investigated the features of the lithosphere structure by magnetic and gravity data. Exploration methods included the application of existing and open source near-surface aeromagnetic (WDMAM) with satellite data both at 100 km and 400 km in altitude (CHAMP) and gravity satellite data (GRACE). Aeromagnetic data have been used for the 2D geomagnetic model for a depth range from 3 to 50 km plotting. Gravity data has allowed to study the 2D density model for a depth range from 5 to 200 km plotting. At the heart of the geomagnetic and density model plotting lies the technique of the spectral-spatial representation of a geomagnetic field converted in a deep geomagnetic model. The technique of the spectral-spatial analysis (SPAN) is used to differentiate the weakly magnetic heterogeneities within the basement. In this paper we have studied the structure of the lithosphere in the area of deep magnetic minima in the vicinity of the eastern part of the Fennoscandian Shield, Central Europe and the northern part of South America. We have found powerful (more than 10 km) permeable feeble magnetic zones in the middle crust (20-30 km in depth) that are detected as feebly magnetic layer using the geomagnetic data. The magnetic minimum at 100 and 400 km in altitude corresponds to this feeble magnetic layer. It stands out as the low density layer at depth 20-35 km and, after the break, at depth 60-100 km. Ground-based magnetotelluric survey has allowed to allocate the high-conductivity layer at depth 15-30 and 60-110 km. It suggests that the detected layers can be rheological weak. The same is for the regions of Central Europe and South America. The powerful feebly magnetic layers have been detected in the middle and bottom crust (30-50 km for the Central Europe and 30-40 km for South America). The low density layers have been found for 20-35 km and 50-80 km in depth. The ground based measurement has confirmed the presence

  15. The influence of age and weaning on permeability of the gastrointestinal tract in Holstein bull calves.

    PubMed

    Wood, K M; Palmer, S I; Steele, M A; Metcalf, J A; Penner, G B

    2015-10-01

    Fourteen Holstein bull calves were used in a randomized complete block design to investigate the effect of calf age and weaning on permeability of the gastrointestinal tract (GIT). Calves were randomly assigned to 1 of 2 treatments: (1) a weaning protocol that was initiated on d 35; WN; n=7), or (2) a control treatment where calves were not weaned (CON; n=7). Calves were bottle-fed milk replacer (150 g/L), in 3 equal portions/d targeting 15% of their body weight (BW) in liquid milk intake [approximately 21.1g/kg of BW/d, dry matter (DM) basis]. On d 35, the amount of milk replacer offered to WN calves was reduced to 7.5% of BW for 7 d before calves were weaned on d 42. On d 14, 28, and 42, calves were orally dosed with 500 mL of Cr-EDTA (179 mM Cr-EDTA solution) and housed in a metabolism crate to enable total urine collection and determination of total urinary Cr recovery as an indicator of total-tract permeability. On d 44, calves were killed and tissues from the rumen, omasum, duodenum, jejunum, ileum, cecum, and proximal and distal colon were collected, rinsed, and transported in buffer solution (pH 7.4 at 38.5°C). Tissues were incubated in Ussing chambers under short-circuit conditions with buffer solutions designed to mimic the mucosal and serosal energy source that would be available in vivo (glucose for tissues from the small intestine and short-chain fatty acids for tissues that would be exposed to fermentation; rumen, omasum, and large intestinal tissues). The serosal to mucosal flux of (14)C-mannitol and (3)H-inulin was measured for each region. Although we detected treatment × period interactions for BW and starter intake, dietary treatments did not differ within a week. Overall, the time that ruminal pH was <5.5 was less before weaning than after weaning. We observed a differential response for the appearance of Cr in urine for WN and CON calves, where the appearance of Cr (mg/48 h) in urine decreased for both treatments from d 14 to 28, but

  16. Predicting the extent of metabolism using in vitro permeability rate measurements and in silico permeability rate predictions

    PubMed Central

    Hosey, Chelsea M; Benet, Leslie Z

    2015-01-01

    The Biopharmaceutics Drug Disposition Classification System (BDDCS) can be utilized to predict drug disposition, including interactions with other drugs and transporter or metabolizing enzyme effects based on the extent of metabolism and solubility of a drug. However, defining the extent of metabolism relies upon clinical data. Drugs exhibiting high passive intestinal permeability rates are extensively metabolized. Therefore, we aimed to determine if in vitro measures of permeability rate or in silico permeability rate predictions could predict the extent of metabolism, to determine a reference compound representing the permeability rate above which compounds would be expected to be extensively metabolized, and to predict the major route of elimination of compounds in a two-tier approach utilizing permeability rate and a previously published model predicting the major route of elimination of parent drug. Twenty-two in vitro permeability rate measurement data sets in Caco-2 and MDCK cell lines and PAMPA were collected from the literature, while in silico permeability rate predictions were calculated using ADMET Predictor™ or VolSurf+. The potential for permeability rate to differentiate between extensively and poorly metabolized compounds was analyzed with receiver operating characteristic curves. Compounds that yielded the highest sensitivity-specificity average were selected as permeability rate reference standards. The major route of elimination of poorly permeable drugs was predicted by our previously published model and the accuracies and predictive values were calculated. The areas under the receiver operating curves were >0.90 for in vitro measures of permeability rate and >0.80 for the VolSurf+ model of permeability rate, indicating they were able to predict the extent of metabolism of compounds. Labetalol and zidovudine predicted greater than 80% of extensively metabolized drugs correctly and greater than 80% of poorly metabolized drugs correctly in Caco

  17. Intrinsic delay of permeable base transistor

    SciTech Connect

    Chen, Wenchao; Guo, Jing; So, Franky

    2014-07-28

    Permeable base transistors (PBTs) fabricated by vacuum deposition or solution process have the advantages of easy fabrication and low power operation and are a promising device structure for flexible electronics. Intrinsic delay of PBT, which characterizes the speed of the transistor, is investigated by solving the three-dimensional Poisson equation and drift-diffusion equation self-consistently using finite element method. Decreasing the emitter thickness lowers the intrinsic delay by improving on-current, and a thinner base is also preferred for low intrinsic delay because of fewer carriers in the base region at off-state. The intrinsic delay exponentially decreases as the emitter contact Schottky barrier height decreases, and it linearly depends on the carrier mobility. With an optimized emitter contact barrier height and device geometry, a sub-nano-second intrinsic delay can be achieved with a carrier mobility of ∼10 cm{sup 2}/V/s obtainable in solution processed indium gallium zinc oxide, which indicates the potential of solution processed PBTs for GHz operations.

  18. Drainage hydraulics of permeable friction courses

    NASA Astrophysics Data System (ADS)

    Charbeneau, Randall J.; Barrett, Michael E.

    2008-04-01

    This paper describes solutions to the hydraulic equations that govern flow in permeable friction courses (PFC). PFC is a layer of porous asphalt approximately 50 mm thick that is placed as an overlay on top of an existing conventional concrete or asphalt road surface to help control splash and hydroplaning, reduce noise, and enhance quality of storm water runoff. The primary objective of this manuscript is to present an analytical system of equations that can be used in design and analysis of PFC systems. The primary assumptions used in this analysis are that the flow can be modeled as one-dimensional, steady state Darcy-type flow and that slopes are sufficiently small so that the Dupuit-Forchheimer assumptions apply. Solutions are derived for cases where storm water drainage is confined to the PFC bed and for conditions where the PFC drainage capacity is exceeded and ponded sheet flow occurs across the pavement surface. The mathematical solutions provide the drainage characteristics (depth and residence time) as a function of rainfall intensity, PFC hydraulic conductivity, pavement slope, and maximum drainage path length.

  19. Complex permeability spectra of permendur composite materials

    NASA Astrophysics Data System (ADS)

    Kasagi, Teruhiro; Tsutaoka, Takanori; Hatakeyama, Kenichi

    2010-01-01

    Complex permeability μ* and permittivity epsilon* spectra of permendur (Co50Fe50) composite materials have been studied in the microwave frequency range considering the application to the left-handed meta-materials and EMC devices. High surface electrical resistance of the permendur particles was achieved by the heat-treatment in order to suppress the eddy current effect in the high particle content composites. For the 82.6 vol.% composite, the μ' is 11 and less than 1 at 100 MHz and 6 GHz, respectively; the μ'' shows the two peaks around 700 MHz and 3GHz due to the domain wall and gyromagnetic spin resonance. On the other hand, the epsilon' is almost constant value of 28 and the epsilon'' is almost zero in the frequency range from 100 MHz to 6 GHz. The calculated reflection loss of a single-layer electromagnetic wave absorber (EM absorber) designed by using permendur composites indicates less than -20 dB around the matching frequency of 1 GHz.

  20. Second law violations, continuum mechanics, and permeability

    NASA Astrophysics Data System (ADS)

    Ostoja-Starzewski, Martin

    2016-03-01

    The violations of the second law are relevant as the length and/or time scales become very small. The second law then needs to be replaced by the fluctuation theorem and mathematically, the irreversible entropy is a submartingale. First, we discuss the consequences of these results for the axioms of continuum mechanics, arguing in favor of a framework relying on stochastic functionals of energy and entropy. We next determine a Lyapunov function for diffusion-type problems governed by stochastic rather than deterministic functionals of internal energy and entropy, where the random field coefficients of diffusion are not required to satisfy the positive definiteness everywhere. Next, a formulation of micropolar fluid mechanics is developed, accounting for the lack of symmetry of stress tensor on molecular scales. This framework is then applied to employed to show that spontaneous random fluctuations of the microrotation field will arise in Couette—and Poiseuille-type flows in the absence of random (turbulence-like) fluctuations of the classical velocity field. Finally, while the permeability is classically modeled by the Darcy law or its modifications, besides considering the violations of the second law, one also needs to account for the spatial randomness of the channel network, implying a modification of the hierarchy of scale-dependent bounds on the macroscopic property of the network.

  1. Permeability of WIPP Salt During Damage Evolution and Healing

    SciTech Connect

    BODNER,SOL R.; CHAN,KWAI S.; MUNSON,DARRELL E.

    1999-12-03

    The presence of damage in the form of microcracks can increase the permeability of salt. In this paper, an analytical formulation of the permeability of damaged rock salt is presented for both initially intact and porous conditions. The analysis shows that permeability is related to the connected (i.e., gas accessible) volumetric strain and porosity according to two different power-laws, which may be summed to give the overall behavior of a porous salt with damage. This relationship was incorporated into a constitutive model, known as the Multimechanism Deformation Coupled Fracture (MDCF) model, which has been formulated to describe the inelastic flow behavior of rock salt due to coupled creep, damage, and healing. The extended model was used to calculate the permeability of rock salt from the Waste Isolation Pilot Plant (WIPP) site under conditions where damage evolved with stress over a time period. Permeability changes resulting from both damage development under deviatoric stresses and damage healing under hydrostatic pressures were considered. The calculated results were compared against experimental data from the literature, which indicated that permeability in damaged intact WIPP salt depends on the magnitude of the gas accessible volumetric strain and not on the total volumetric strain. Consequently, the permeability of WIPP salt is significantly affected by the kinetics of crack closure, but shows little dependence on the kinetics of crack removal by sintering.

  2. Stress-Induced Permeability Anisotropy of Resedimented Boston Blue Clay

    NASA Astrophysics Data System (ADS)

    Adams, A. L.; Germaine, J. T.; Flemings, P. B.

    2011-12-01

    Significant permeability anisotropy, defined as the ratio of horizontal to vertical permeability, can develop in a homogenous material due to one dimensional compression. In Resedimented Boston Blue Clay (RBBC), a low plasticity glacio-marine illitic clay, the permeability anisotropy increases from 1.22 to 1.85 as the porosity decreases from 0.5 to 0.37. The permeability decreases by greater than one order of magnitude over this porosity range, ranging from 7.5 x 10-17 m2 to 3.9 x 10-18 m2 vertically and from 9.1 x 10-17 m2 to 7.2 x 10-18 m2 horizontally. SEM images, taken at different orientations and stress levels, reveal that pores become increasingly elongate perpendicular to the maximum (vertical) loading direction as stress is increased. We interpret that rotation of platy materials creates this fabric. To make these measurements, a new method to measure the permeability anisotropy using cubic specimens was developed. In addition, we correct for test sequence bias and minimize scatter in the data set to produce a well defined permeability anisotropy vs. porosity trend. A better understanding of the evolution of permeability anisotropy during sediment burial is important for understanding a range of transport processes in the subsurface.

  3. Characterization and estimation of permeability correlation structure from performance data

    SciTech Connect

    Ershaghi, I.; Al-Qahtani, M.

    1997-08-01

    In this study, the influence of permeability structure and correlation length on the system effective permeability and recovery factors of 2-D cross-sectional reservoir models, under waterflood, is investigated. Reservoirs with identical statistical representation of permeability attributes are shown to exhibit different system effective permeability and production characteristics which can be expressed by a mean and variance. The mean and variance are shown to be significantly influenced by the correlation length. Detailed quantification of the influence of horizontal and vertical correlation lengths for different permeability distributions is presented. The effect of capillary pressure, P{sub c1} on the production characteristics and saturation profiles at different correlation lengths is also investigated. It is observed that neglecting P{sub c} causes considerable error at large horizontal and short vertical correlation lengths. The effect of using constant as opposed to variable relative permeability attributes is also investigated at different correlation lengths. Next we studied the influence of correlation anisotropy in 2-D reservoir models. For a reservoir under five-spot waterflood pattern, it is shown that the ratios of breakthrough times and recovery factors of the wells in each direction of correlation are greatly influenced by the degree of anisotropy. In fully developed fields, performance data can aid in the recognition of reservoir anisotropy. Finally, a procedure for estimating the spatial correlation length from performance data is presented. Both the production performance data and the system`s effective permeability are required in estimating the correlation length.

  4. Permeability alteration induced by drying of brines in porous media

    NASA Astrophysics Data System (ADS)

    Peysson, Y.

    2012-11-01

    Permeability of reservoir rocks can be strongly altered by salt precipitation induced by drying. Indeed, gas injection in deep saline aquifers leads first to the brine displacement. The liquid saturation decreases near the injection point and reaches a residual water saturation. But at longer time, the water mass transfer to the gas phase by evaporation can become significant and the dissolved salt can precipitate in the porous structure. The solid salts fill the pores and the permeability decreases. Permeability alteration by salting out is a risk of injectivity decline in the context of CO2 geological storage in saline aquifers where high level of gas injection has to be maintained over decades. However, this problem has been poorly investigated. It implies physical processes that are strongly coupled: drying, water and gas flows in the porous structure and precipitation. This work is an experimental investigation aiming at measuring on natural rock samples the permeability alteration induced by convective drying where dry gas is injected through the sample. We show that alteration of permeability is strong and total blockage of the flow is even possible. We also show that the change in porosity due to the solid salt is heterogeneous along the rock samples. A local permeability-porosity relationship has been estimated from the measurements and we could deduce the permeability alteration function of time by modeling the drying dynamic. We show that it starts very early because capillary backflows are extremely efficient in this process to accumulate solid salt near the injection surfaces.

  5. Sucrose, xylitol, and erythritol increase PMMA permeability for depot antibiotics.

    PubMed

    McLaren, Alex C; McLaren, Sandra G; Hickmon, Miranda K

    2007-08-01

    Release of antibiotics from antibiotic-loaded PMMA is dependent on its permeability. Loading PMMA with soluble particulate filler has been proposed to increase permeability and antibiotic release for beads and spacers. We therefore assessed particulate sucrose, xylitol, and erythritol as fillers to increase the permeability and elution kinetics of filler-loaded PMMA. Based on lower solubility, we hypothesized that erythritol would not enhance permeability and elution as much as xylitol and sucrose. We made filler-loaded PMMA beads with each of the three fillers combined with phenolphthalein, and soaked in 0.1% NaOH solution. Permeability was assessed qualitatively by relative depth of phenolphthalein color change caused by penetration of NaOH solution into subsequently split beads. Elution was quantitatively assessed by spectrophotometric light absorption measurements of the eluent. Fluid penetration reached the center of 7-mm beads by day 15, similar for all three materials. Elution of phenolphthalein was greater for xylitol than for the other two materials. Particulate sucrose, xylitol, and erythritol fillers increase PMMA permeability and elution kinetics but relative solubility did not determine the relative degree of enhancement of permeability and elution by these materials. PMID:17549030

  6. Stress dependence of permeability of intact and fractured shale cores.

    NASA Astrophysics Data System (ADS)

    van Noort, Reinier; Yarushina, Viktoriya

    2016-04-01

    Whether a shale acts as a caprock, source rock, or reservoir, understanding fluid flow through shale is of major importance for understanding fluid flow in geological systems. Because of the low permeability of shale, flow is thought to be largely confined to fractures and similar features. In fracking operations, fractures are induced specifically to allow for hydrocarbon exploration. We have constructed an experimental setup to measure core permeabilities, using constant flow or a transient pulse. In this setup, we have measured the permeability of intact and fractured shale core samples, using either water or supercritical CO2 as the transporting fluid. Our measurements show decreasing permeability with increasing confining pressure, mainly due to time-dependent creep. Furthermore, our measurements show that for a simple splitting fracture, time-dependent creep will also eliminate any significant effect of this fracture on permeability. This effect of confinement on fracture permeability can have important implications regarding the effects of fracturing on shale permeability, and hence for operations depending on that.

  7. IMPACT OF CAPILLARY AND BOND NUMBERS ON RELATIVE PERMEABILITY

    SciTech Connect

    Kishore K. Mohanty

    2002-09-30

    Recovery and recovery rate of oil, gas and condensates depend crucially on their relative permeability. Relative permeability in turn depends on the pore structure, wettability and flooding conditions, which can be represented by a set of dimensionless groups including capillary and bond numbers. The effect of flooding conditions on drainage relative permeabilities is not well understood and is the overall goal of this project. This project has three specific objectives: to improve the centrifuge relative permeability method, to measure capillary and bond number effects experimentally, and to develop a pore network model for multiphase flows. A centrifuge has been built that can accommodate high pressure core holders and x-ray saturation monitoring. The centrifuge core holders can operate at a pore pressure of 6.9 MPa (1000 psi) and an overburden pressure of 17 MPa (2500 psi). The effect of capillary number on residual saturation and relative permeability in drainage flow has been measured. A pore network model has been developed to study the effect of capillary numbers and viscosity ratio on drainage relative permeability. Capillary and Reynolds number dependence of gas-condensate flow has been studied during well testing. A method has been developed to estimate relative permeability parameters from gas-condensate well test data.

  8. A novel fluorescence-based cellular permeability assay.

    PubMed

    Chandra, Ankur; Barillas, Samuel; Suliman, Ahmed; Angle, Niren

    2007-04-10

    Vascular permeability is a pathologic process in many disease states ranging from metastatic progression of malignancies to ischemia-reperfusion injury. In order to more precisely study tissue, and more specifically cell layer permeability, our goal was to create a fluorescence-based assay which could quantify permeability without radioactivity or electrical impedance measurements. Human aortic endothelial cells were grown in monolayer culture on Costar-Transwell clear polyester membrane 6-well cell culture inserts. After monolayer integrity was confirmed, vascular endothelial growth factor (VEGF(165)) at varying concentrations with a fixed concentration of yellow-green fluorescent 0.04 microm carboxylate-modified FluoSpheres microspheres were placed in the luminal chamber and incubated for 24 h. When stimulated with VEGF(165) at 20, 40, 80, and 100 ng/ml, this assay system was able to detect increases in trans-layer flux of 8.2+/-2.4%, 16.0+/-3.7%, 41.5+/-4.9%, and 58.6+/-10.1% for each concentration, respectively. This represents the first fluorescence-based permeability assay with the sensitivity to detect changes in the permeability of a cell layer to fluid flux independent of protein flux; as well as being simpler and safer than previous radioactive-and impedance-based permeability assays. With the application of this in vitro assay to a variety of pathologic conditions, both the dynamics and physiology relating to cellular permeability can be more fully investigated. PMID:16962665

  9. Scale Dependence of Equivalent Permeability Tensor in Naturally Fractured Reservoirs

    NASA Astrophysics Data System (ADS)

    Azizmohammadi, S.; Matthäi, S. K.; Paul, J. D.

    2012-04-01

    Fracture geometries in naturally fractured reservoirs are usually inferred from sparse subsurface observations from well logs or cores. Since the largest fractures tend to be the least frequent, they are often undersampled. Therefore, interpretations based on samples taken at any scale smaller than that of interest contain a bias, misrepresenting the true characteristics of the fracture system. This bias may lead to the incorrect characterisation of the reservoir, upscaling and gridding. In this work, we investigate the variation of the equivalent permeability and its anisotropy in naturally fractured rocks as a function of sample size. We use a two dimensional linear elastic model of fracture aperture, taking into account the far-field stresses in conjunction with the parallel plate model, to determine fracture permeability. These apertures are applied to fractured reservoir analogues mapped in the field to numerically estimate permeability. We then employ a finite element scheme to compute equivalent permeability tensors for random samples of the fractured porous medium at specific length scales. We find that the distribution of the principle component of equivalent permeability tensor computed at each scale size appears to be dependent upon the underlying attributes of the fracture networks. We notice a clear trend between the mean equivalent permeability and sample size. Our findings suggest that fracture geometries in naturally fractured reservoirs should be sampled at the scales of interest; if not, the equivalent permeability of such reservoirs might be significantly underestimated.

  10. Age-related changes in mouse bone permeability.

    PubMed

    Rodriguez-Florez, Naiara; Oyen, Michelle L; Shefelbine, Sandra J

    2014-03-21

    The determination of lacunar-canalicular permeability is essential for understanding local fluid flow in bone, which may indicate how bone senses changes in the mechanical environment to regulate mechano-adaptation. The estimates of lacunar-canalicular permeability found in the literature vary by up to eight orders of magnitude, and age-related permeability changes have not been measured in non-osteonal mouse bone. The objective of this study is to use a poroelastic approach based on nanoindentation data to characterize lacunar-canalicular permeability in murine bone as a function of age. Nine wild type C57BL/6 mice of different ages (2, 7 and 12 months) were used. Three tibiae from each age group were embedded in epoxy resin, cut in half and indented in the longitudinal direction in the mid-cortex using two spherical fluid indenter tips (R=238 μm and 500 μm). Results suggest that the lacunar-canalicular intrinsic permeability of mouse bone decreases from 2 to 7 months, with no significant changes from 7 to 12 months. The large indenter tip imposed larger contact sizes and sampled larger ranges of permeabilities, particularly for the old bone. This age-related difference in the distribution was not seen for indents with the smaller radius tip. We conclude that the small tip effectively measured lacunar-canalicular permeability, while larger tip indents were influenced by vascular permeability. Exploring the age-related changes in permeability of bone measured by nanoindentation will lead to a better understanding of the role of fluid flow in mechano-transduction. This understanding may help indicate alterations in bone adaptation and remodeling. PMID:24433671

  11. Patterns of effective permeability of leaf cuticles to acids

    SciTech Connect

    Hauser, H.D.; Walters, K.D.; Berg, V.S. )

    1993-01-01

    Plants in the field are frequently exposed to anthropogenic acid precipitation with pH values of 4 and below. For the acid to directly affect leaf tissues, it must pass through the leaf cuticle, but little is known about the permeability of cuticles to protons, of about the effect of different anions on this permeability. We investigated the movement of protons through isolated astomatous leaf cuticles of grapefruit (Citrus x paradisi Macfady.), rough lemon (Citrus limon [L.] Burm. fils cv Ponderosa), and pear (Pyrus communis L.) using hydrochloric, sulfuric, and nitric acids. Cuticles were enzymically isolated from leaves and placed in a diffusion apparatus with pH 4 acid on the morphological outer surface of the cuticle and degassed distilled water on the inner surface. Changes in pH of the solution on the inner surface were used to determine rates of effective permeability of the cuticles to the protons of these acids. Most cuticles exhibited an initial low permeability, lasting hours to days, then after a short transition displayed a significant higher permeability, which persisted until equilibrium was approached. The change in effective permeability appears to be reversible. Effective permeabilities were higher for sulfuric acid than for the others. A model of the movement of protons through the cuticle is presented, proposing that dissociated acid groups in channels within the cutin are first protonated by the acid, accounting for the low initial effective permeability; then protons pass freely through the channels, resulting in a higher effective permeability. 26 refs., 6 figs., 2 tabs.

  12. Fractal Theory for Permeability Prediction, Venezuelan and USA Wells

    NASA Astrophysics Data System (ADS)

    Aldana, Milagrosa; Altamiranda, Dignorah; Cabrera, Ana

    2014-05-01

    Inferring petrophysical parameters such as permeability, porosity, water saturation, capillary pressure, etc, from the analysis of well logs or other available core data has always been of critical importance in the oil industry. Permeability in particular, which is considered to be a complex parameter, has been inferred using both empirical and theoretical techniques. The main goal of this work is to predict permeability values on different wells using Fractal Theory, based on a method proposed by Pape et al. (1999). This approach uses the relationship between permeability and the geometric form of the pore space of the rock. This method is based on the modified equation of Kozeny-Carman and a fractal pattern, which allows determining permeability as a function of the cementation exponent, porosity and the fractal dimension. Data from wells located in Venezuela and the United States of America are analyzed. Employing data of porosity and permeability obtained from core samples, and applying the Fractal Theory method, we calculated the prediction equations for each well. At the beginning, this was achieved by training with 50% of the data available for each well. Afterwards, these equations were tested inferring over 100% of the data to analyze possible trends in their distribution. This procedure gave excellent results in all the wells in spite of their geographic distance, generating permeability models with the potential to accurately predict permeability logs in the remaining parts of the well for which there are no core samples, using even porority logs. Additionally, empirical models were used to determine permeability and the results were compared with those obtained by applying the fractal method. The results indicated that, although there are empirical equations that give a proper adjustment, the prediction results obtained using fractal theory give a better fit to the core reference data.

  13. Measurement of the intestinal permeability in chronic kidney disease

    PubMed Central

    Terpstra, Matty L; Singh, Ramandeep; Geerlings, Suzanne E; Bemelman, Frederike J

    2016-01-01

    AIM: To evaluate methods measuring the intestinal per-meability in chronic kidney disease (CKD) and clarify whether there is an increased intestinal permeability in CKD. METHODS: We reviewed the literature in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-analysis (PRISMA) protocol and performed a systematic literature search through MEDline and EMBASE. All controlled trials and cohort studies using non-invasive methods to assess intestinal permeability in CKD patients were included. Excluded were: Conference abstracts and studies including patients younger than 18 years or animals. From the included studies we summarized the used methods and their advantages and disadvantages. For the comparison of their results we divided the included studies in two categories based on their included patient population, either assessing the intestinal permeability in mild to moderate CKD patients or in end stage renal disease (ESRD) patients. Results were graphically displayed in two plots, one comparing the intestinal permeability in mild to moderate CKD patients to healthy controls and one comparing the intestinal permeability in ESRD patients to healthy controls. RESULTS: From the 480 identified reports, 15 met our inclusion criteria. Methods that were used to assess the intestinal permeability varied from markers measured in plasma to methods based on calculating the urinary excretion of an orally administered test substance. None of the applied methods has been validated in CKD patients and the influence of decreased renal function on the different methods remains unclear to a certain extent. Methods that seem the least likely to be influenced by decreased renal function are the quantitative PCR (qPCR) for bacterial DNA in blood and D-lactate. Considering the results published by the included studies; the studies including patients with mild to moderate CKD conducted conflicting results. Some studies did report an increase in intestinal

  14. Method for plugging high permeability zones in subterranean reservoirs

    SciTech Connect

    Christopher, C.; Clauset, A.

    1980-07-01

    A description is given of a method for plugging high permeability areas within a subterranean reservoir penetrated by at least one injection well and at least one production well, said wells being in fluid communication with each other, comprising infecting through at least one of said wells an effective amount of an aqueous solution comprising fresh wter and a pectic substance selected from the group consisting pectins, pectates, polygalacturonic acids and mixtures thereof into said high permeability areas wherein the aqueous solution contacts a brine which causes the pectic substance to form a gel thereby effectively plugging the high permeability areas within the reservoir.

  15. Timescales for permeability reduction and strength recovery in densifying magma

    NASA Astrophysics Data System (ADS)

    Heap, M. J.; Farquharson, J. I.; Wadsworth, F. B.; Kolzenburg, S.; Russell, J. K.

    2015-11-01

    Transitions between effusive and explosive behaviour are routine for many active volcanoes. The permeability of the system, thought to help regulate eruption style, is likely therefore in a state of constant change. Viscous densification of conduit magma during effusive periods, resulting in physical and textural property modifications, may reduce permeability to that preparatory for an explosive eruption. We present here a study designed to estimate timescales of permeability reduction and strength recovery during viscous magma densification by coupling measurements of permeability and strength (using samples from a suite of variably welded, yet compositionally identical, volcanic deposits) with a rheological model for viscous compaction and a micromechanical model, respectively. Bayesian Information Criterion analysis confirms that our porosity-permeability data are best described by two power laws that intersect at a porosity of 0.155 (the "changepoint" porosity). Above and below this changepoint, the permeability-porosity relationship has a power law exponent of 8.8 and 1.0, respectively. Quantitative pore size analysis and micromechanical modelling highlight that the high exponent above the changepoint is due to the closure of wide (∼200-300 μm) inter-granular flow channels during viscous densification and that, below the changepoint, the fluid pathway is restricted to narrow (∼50 μm) channels. The large number of such narrow channels allows porosity loss without considerable permeability reduction, explaining the switch to a lower exponent. Using these data, our modelling predicts a permeability reduction of four orders of magnitude (for volcanically relevant temperatures and depths) and a strength increase of a factor of six on the order of days to weeks. This discrepancy suggests that, while the viscous densification of conduit magma will inhibit outgassing efficiency over time, the regions of the conduit prone to fracturing, such as the margins, will

  16. An analytical model for permeability of isotropic porous media

    NASA Astrophysics Data System (ADS)

    Yang, Xiaohu; Lu, Tian Jian; Kim, Tongbeum

    2014-06-01

    We demonstrate that permeability of isotropic porous media e.g., open-cell foams can be analytically presented as a function of two morphological parameters: porosity and pore size. Adopting a cubic unit cell model, an existing tortuosity model from the branching algorithm method is incorporated into a generalized permeability model. The present model shows that dimensionless permeability significantly increases as the porosity of isotropic porous media and unifies the previously reported data in a wide range of porosity (ɛ=0.55-0.98) and pore size (Dp=0.254 mm-5.08 mm).

  17. Fractal Analysis of Stress Sensitivity of Permeability in Porous Media

    NASA Astrophysics Data System (ADS)

    Tan, Xiao-Hua; Li, Xiao-Ping; Liu, Jian-Yi; Zhang, Lie-Hui; Cai, Jianchao

    2015-12-01

    A permeability model for porous media considering the stress sensitivity is derived based on mechanics of materials and the fractal characteristics of solid cluster size distribution. The permeability of porous media considering the stress sensitivity is related to solid cluster fractal dimension, solid cluster fractal tortuosity dimension, solid cluster minimum diameter and solid cluster maximum diameter, Young's modulus, Poisson's ratio, as well as power index. Every parameter has clear physical meaning without the use of empirical constants. The model predictions of permeability show good agreement with those obtained by the available experimental expression. The proposed model may be conducible to a better understanding of the mechanism for flow in elastic porous media.

  18. Shear-induced permeability anisotropy of simulated serpentinite gouge

    NASA Astrophysics Data System (ADS)

    Okazaki, K.; Katayama, I.; Noda, H.; Takahashi, M.

    2012-12-01

    Fluids in fault zone play an important role on mechanical weakening of fault strength due to elevated pore fluid pressures and absorbed on the crystal surface. The heterogeneous occurrence of earthquake in subduction zone are probably linked to the heterogeneous distribution of fluids that have significant influence on the fault instability. Permeability in fault zone control fluid flow in In this study, permeability in three orthogonal directions of antigorite serpentinite gouge was measured during pre-cut frictional experiments using triaxial gas apparatus in Hiroshima University. kx, ky, and kz denote permeabilities in the slip direction, normal to the slip direction in the fault, and normal to the fault. All experiments were conducted at a room temperature, a confining pressure of 150 MPa, a pore pressure of 100 MPa, and a constant slip rate of 0.575 μm/s while the initial gouge thickness is about 1.2 mm. Permeabilities in different directrions are measured for different but similar samples continuously during shear deformation by the pore pressure oscillation method [e.g., Fischer and Paterson, 1992]. The friction coefficient reached its maximum value at a slip displacement of about 0.8 mm. Permeabilities in all directions decreases by one order of magnitude until this point without showing significant anisotropy. After the shear stress reaches steady-state, anisotropy of permeability becomes remarkable. At the steady state in terms of shear stress, permeability anisotropies kx/kz and ky/kz stayed at their steady state value as high as nearly one order magnitude. Microstructures of recovered samples suggest that the permeability anisotropy is caused by developments of R- and P-shear band structures that may act as fluid conduits and encourage fluid flow parallel to the fault in serpentinite gouge. These permeability anisotropies may enhance fluid flow along subduction plate interface and active fault zones. In addition, this anisotropic permeability structure

  19. Quantifying the complex permittivity and permeability of magnetic nanoparticles

    NASA Astrophysics Data System (ADS)

    Yao, B. M.; Gui, Y. S.; Worden, M.; Hegmann, T.; Xing, M.; Chen, X. S.; Lu, W.; Wroczynskyj, Y.; van Lierop, J.; Hu, C.-M.

    2015-04-01

    The complex permittivity and permeability of superparamagnetic iron-oxide nanoparticles has been quantified using a circular waveguide assembly with a static magnetic field to align the nanoparticle's magnetization. The high sensitivity of the measurement provides the precise resonant feature of nanoparticles. The complex permeability in the vicinity of ferromagnetic resonance is in agreement with the nanoparticle's measured magnetization via conventional magnetometry. A rigorous and self-consistent measure of complex permittivities and permeabilities of nanoparticles is crucial to ascertain accurately the dielectric behaviour as well as the frequency response of nanoparticle magnetization, necessary ingredients when designing and optimizing magnetic nanoparticles for biomedical applications.

  20. Preasymptotic hydrodynamic dispersion as a quantitative probe of permeability.

    PubMed

    Brosten, Tyler R; Vogt, Sarah J; Seymour, Joseph D; Codd, Sarah L; Maier, Robert S

    2012-04-01

    We interpret a generalized short-time expansion of stochastic hydrodynamic dispersion dynamics in the case of small Reynolds number flow through macroscopically homogenous permeable porous media to directly determine hydrodynamic permeability. The approach allows determination of hydrodynamic permeability from pulsed field gradient spin-echo nuclear magnetic resonance measurement of the short-time effective hydrodynamic dispersion coefficient. The analytical expansion of asymptotic dynamics agrees with experimental NMR data and lattice Boltzmann simulation of hydrodynamic dispersion in consolidated random sphere pack media. PMID:22680531

  1. Effects of Aspirin on Gastroduodenal Permeability in Alcoholics and Controls

    PubMed Central

    Farhadi, Ashkan; Keshavarzian, Ali; Kwasny, Mary J.; Shaikh, Maliha; Fogg, Louis; Lau, Cynthia; Fields, Jeremy Z.; Forsyth, Christopher B.

    2010-01-01

    Alcohol and non-steroidal anti-inflammatory drugs (NSAIDS) are noxious agents that can disrupt the integrity of the gastroduodenal mucosal and damage the epithelial barrier, and lead to increased gastroduodenal permeability. Moreover, it is not uncommon that patients are exposed to these two barrier stressors at the same time. It is thus important to know how simultaneous exposure affects the gastroduodenal barrier, and acquiring that knowledge was the goal of this study. We used a method that has been widely used for the assessment of injury to the gastroduodenal barrier induced by these noxious agents – measurement of gastroduodenal permeability as indicated by urinary excretion of ingested sucrose. We used gas chromatography to measure the amount of sucrose excreted in the urine over the 5–12 h following ingestion of a bolus of sucrose. The 148 participants in the study included 92 alcoholics and 56 healthy controls. All study subjects had a baseline permeability test. To determine whether addition of a second noxious agent, in addition to chronic alcohol, further decreases gastroduodenal barrier integrity, a subset of 118 study subjects participated in another permeability test in which they were exposed to aspirin. For this test, participants ingested 1300 mg aspirin twice, 12 hours and 1 hour before the final permeability test. The baseline permeability test showed that alcoholics have significantly higher gastroduodenal permeability than controls. Aspirin caused a significant within group absolute increase in gastroduodenal permeability in both alcoholics and controls (+7.72%, p=0.003 and +2.25%, p = 0.011, respectively) but the magnitude of these increases were not significantly different from each other. Baseline permeability did vary by gender, self-reported illegal drug use, and employment type. The extent of the permeability increase after aspirin ingestion varied with illegal drug use and recruitment site (a surrogate marker of socioeconomic status

  2. Instrumentation for Measurement of Gas Permeability of Polymeric Membranes

    NASA Technical Reports Server (NTRS)

    Upchurch, Billy T.; Wood, George M.; Brown, Kenneth G.; Burns, Karen S.

    1993-01-01

    A mass spectrometric 'Dynamic Delta' method for the measurement of gas permeability of polymeric membranes has been developed. The method is universally applicable for measurement of the permeability of any gas through polymeric membrane materials. The usual large sample size of more than 100 square centimeters required for other methods is not necessary for this new method which requires a size less than one square centimeter. The new method should fulfill requirements and find applicability for industrial materials such as food packaging, contact lenses and other commercial materials where gas permeability or permselectivity properties are important.

  3. Predicting the permeability of sedimentary rocks from microstructure

    SciTech Connect

    Schlueter, E.M.

    1995-01-01

    Permeability is linked to other properties of porous media such as capillary pressure and relative permeability. In order to understand the relationships, one has to understand how all those properties are conditioned by the connectivity and geometrical properties of the pore space. In this study, we look at a natural porous material which is defined as a two-phase material in which the interconnected pore space constitutes one phase and the solid matrix the other. Laboratory samples are tested using fluid flow experiments to determine the relationship of macroscopic properties such as permeability to rock microstructure. Kozeny-Carman and other equations are developed to further quantify these relationships.

  4. Permeability anisotropy of serpentinite and fluid migration in subduction zones

    NASA Astrophysics Data System (ADS)

    Kawano, S.; Katayama, I.; Okazaki, K.

    2010-12-01

    Subduction zones are the place where water is transported into the Earth's interior and causes arc volcanism and seismic activities. Subducting slabs release most of the water to the mantle wedge by the dehydration reactions, and the expelled water reacts with mantle rocks, forming serpentinite at the plate interface. The existence of hydrous layer has been detected by low- velocity anomaly and high-Poison's ratio in several subduction zones (Kamiya and Kobayashi 2000 ; Brocher et al. 2003). The migration of water is generally considered to move upward by buoyancy in the mantle. However, if the hydrous layer is extensively deformed, the migration of water can be controlled by the deformation plane within such layer. In order to test this hypothesis, we analyzed the permeability anisotropy of serpentinite with a strongly-developed schistosity and discuss fluid migration in the subduction systems. Serpentinite samples were collected from Nishisonogi metamorphic terrane in Nagasaki, which schistosity is well-defined developed. Two types of experimental samples were prepared: one is parallel to schistosity and the other is perpendicular. We used intra-vessel deformation and fluid- flow apparatus (IVA) in Hiroshima University to measure the permeability. In this study, we measured gas permeability using nitrogen gas and water permeability under isotropic pressure. Gas permeability was measured using the constant flow method, and water permeability was similar to gas and the transient pulse method was also used. The experiments were conducted at confining pressures up to 50 MPa, pore pressures up to 8 MPa at room temperature. We converted gas permeability to intrinsic permeability with Klinkenberg effect. The permeability decreased with increasing confining pressure, and intrinsic permeability of samples parallel to schistosity were about 10^-20 m2 at confining pressure of 50 MPa. We observed two types of pressure effect: one is significant decline due to crack filling

  5. Permeability of filters used for immunoisolation.

    PubMed

    Iwata, H; Morikawa, N; Ikada, Y

    1996-01-01

    Immunoisolation of islets of Langerhans (islets) by their enclosure in a filter to isolate them from the host immune system following implantation is a particularly attractive method for bioartificial pancreas. The filter should have excellent semipermeability so that damaging components of the immune system cannot reach the implanted islets. In addition, oxygen and nutrients should be supplied at a sufficiently high rate to maintain tissue viability. In the present work we conducted in vitro diffusion studies of solutes with various molecular sizes through Nuclepore filters and an XM-50 ultrafilter, which have been preferentially used for immunoisolation. The high permeability of microsolutes was not reduced much by the presence of any filters, implying that oxygen and nutrients could be effectively supplied to living cells by diffusion even if enclosed in a filter. Since the predominant cause of allograft rejection is activation of cellular immunity by T lymphocyte, while humoral immunity including antibodies and complement proteins plays a major role in the rejection of xenografts, requirements for the semipermeability of filters highly depends on the donor of islet tissue. T lymphocytes with a diameter of about 10 microm can permeate through neither Nuclepore nor XM-50 filters because their pore size is less than 2 microm. Therefore all of the filters are anticipated to act as effective immunobarrier for islet allografts. Although the XM-50 ultrafilter and 0.015-microm-diameter Nuclepore filter can sharply fractionate macromolecules in accordance with their size (around 50 kD) in a pressure-driven process such as ultrafiltration, these filters were found to lose the fractionation efficiency of macrosolutes in a concentration-driven process such as diffusion. In other words, neither the Nuclepore filters nor the XM-50 ultrafilter could prevent passage of immunoglobulin G in the diffusion process. This finding suggests that these filters cannot protect xenogeneic

  6. Composites with tuned effective magnetic permeability

    NASA Astrophysics Data System (ADS)

    Amirkhizi, Alireza V.; Nemat-Nasser, Sia

    2007-07-01

    Pendry et al. [J. B. Pendry, A. J. Holden, D. J. Robbins, and W. J. Stewart, IEEE Trans. Microwave Theory Tech. 47, 2075 (1999)] and Smith et al. [D. R. Smith, W. J. Padilla, D. C. Vier, S. C. Nemat-Nasser, and S. Schultz, Phys. Rev. Lett. 84, 4184 (2000)] have shown that the effective magnetic permeability, μ, of free space can be rendered negative over a certain frequency range by a periodic arrangement of very thin conductors with suitable magnetic resonance properties, the so-called split-ring resonators. Because of its rather bulky architecture, this structure does not lend itself to a proper integration into a reasonably thin real composite structural panel. To remedy this fundamental barrier, we invented a new magnetic resonator consisting of very thin folded plates that are suitably nested within one another to form folded-doubled resonators (FDRs) that can be integrated into an actual composite panel. Measurements, using a focused beam electromagnetic characterization system combined with time-domain numerical simulations of the reflection and transmission coefficients of such a composite slab have revealed that indeed the composite has a negative μ over a frequency range of about 9.1-9.35 GHz [S. Nemat-Nasser, S. C. Nemat-Nasser, T. A. Plaisted, A. Starr, and A. Vakil Amirkhizi, in Biomimetics: Biologically Inspired Technologies, edited by Y. Bar Cohen (CRC Press, Boca Raton, FL, 2006)]. Thus, it has become possible to construct a structural composite panel with negative index of refraction by simultaneously creating negative effective ɛ and μ [V. G. Veselago, Sov. Phys. Usp. 10, 509 (1968); R. A. Shelby, D. R. Smith, and S. Schultz, Science 292, 77 (2001); A. F. Starr, P. M. Rye, D. R. Smith, and S. Nemat-Nasser, Phys. Rev. B 70, 113102 (2004)].

  7. Probing permeability and microstructure: Unravelling the role of a low-permeability dome on the explosivity of Merapi (Indonesia)

    NASA Astrophysics Data System (ADS)

    Kushnir, Alexandra R. L.; Martel, Caroline; Bourdier, Jean-Louis; Heap, Michael J.; Reuschlé, Thierry; Erdmann, Saskia; Komorowski, Jean-Christophe; Cholik, Noer

    2016-04-01

    Low permeability dome rocks may contribute to conduit overpressure development in volcanic systems, indirectly abetting explosive activity. The permeability of dome-forming rocks is primarily controlled by the volume, type (vesicles and/or microcracks), and connectivity of the void space present. Here we investigate the permeability-porosity relationship of dome-forming rocks and pumice clasts from Merapi's 1888 to 2013 eruptions and assess their possible role in eruptive processes, with particular emphasis on the 2010 paroxysmal eruption. Rocks are divided into three simple field classifications common to all eruptions: Type 1 samples have low bulk density and are pumiceous in texture; Type 2 samples, ubiquitous to the 2010 eruption, are dark grey to black in hand sample and vary greatly in vesicularity; and Type 3 samples are weakly vesicular, light grey in hand sample, and are the only samples that contain cristobalite. Type 2 and Type 3 rocks are present in all eruptions and their permeability and porosity data define similar power law relationships, whereas data for Type 1 samples are clearly discontinuous from these trends. A compilation of permeability and porosity data for andesites and basaltic andesites with published values highlights two microstructural transitions that exert control on permeability, confirmed by modified Bayesian Information Criterion (BIC) analysis. Permeability is microcrack- and diktytaxitic-controlled at connected porosities, φc, < 10.5 vol.%; vesicle- and microcrack-controlled at 10.5 < φc < 31 vol.%; and likely vesicle-controlled for φc > 31 vol.%. Type 3 basaltic andesites, the least permeable of the measured samples and therefore the most likely to have originated in the uppermost low-permeability dome, are identified as relicts of terminal domes (the last dome extruded prior to quiescence). Cristobalite commonly found in the voids of Type 3 blocks may not contribute significantly to the reduction of the permeability of

  8. Boundary Layer Flow over a Rotating Permeable Plane

    NASA Astrophysics Data System (ADS)

    Mehta, K.; Rao, K.

    1994-06-01

    This paper examines the effect of permeability on boundary layerflow over an infinite permeable bed rotatingin a mass of still fluid occupying the upper half space.The slip boundar condition proposed by Beavers and Joseph1) isemployed to analyse the dynamic coupling of boundary layer flowwith the Darcy flow induced in the bed due to transfer of momentumby seepage into the porous medium,occupying the lower half space below the fluid.The effect of permeability and rotation on the componentsof slip velocity and shear stress in the radialand transverse directions is examined.Rotation and tangential slip are found to cause axial flow reversalin the boundary layer.Dependence of the location of point of flow reversalon rotation and permeability has been also studied.

  9. Xenon NMR measurements of permeability and tortuosity in reservoir rocks.

    PubMed

    Wang, Ruopeng; Pavlin, Tina; Rosen, Matthew Scott; Mair, Ross William; Cory, David G; Walsworth, Ronald Lee

    2005-02-01

    In this work we present measurements of permeability, effective porosity and tortuosity on a variety of rock samples using NMR/MRI of thermal and laser-polarized gas. Permeability and effective porosity are measured simultaneously using MRI to monitor the inflow of laser-polarized xenon into the rock core. Tortuosity is determined from measurements of the time-dependent diffusion coefficient using thermal xenon in sealed samples. The initial results from a limited number of rocks indicate inverse correlations between tortuosity and both effective porosity and permeability. Further studies to widen the number of types of rocks studied may eventually aid in explaining the poorly understood connection between permeability and tortuosity of rock cores. PMID:15833638

  10. Method of determining vertical permeability of a subsurface earth formation

    SciTech Connect

    Prasad, R.K.

    1992-10-20

    This patent describes a method of determining vertical permeability of a subsurface earth formation. It comprises: perforating a production casing for an initial area less than a thickness of the subsurface earth formation; measuring reservoir fluid flow and pressure through the initial area perforation in the production casing; perforating the production casing for a production interval having an area greater than the initial area; measuring reservoir fluid flow and pressure through the perforated production interval; establishing a value corresponding to horizontal permeability from the measured reservoir fluid flow through the perforated production interval; simulating pressure profiles using values of vertical permeability in combination with the established value of horizontal permeability; and determining the simulated pressure profile which generally corresponds to a measured pressure profile from the initial area perforation.

  11. Quantifying tight-gas sandstone permeability via critical path analysis

    NASA Astrophysics Data System (ADS)

    Ghanbarian, Behzad; Torres-Verdín, Carlos; Skaggs, Todd H.

    2016-06-01

    Rock permeability has been actively investigated over the past several decades by the geosciences community. However, its accurate estimation still presents significant technical challenges, particularly in spatially complex rocks. In this short communication, we apply critical path analysis (CPA) to estimate permeability in porous rocks from measured mercury intrusion porosimetry and electrical conductivity data. Theoretical estimations of various CPA-based models are then compared to experimental measurements using eighteen tight-gas sandstones. Except for two of the samples, we find permeability estimations performed with the Skaggs model (assuming pore diameter independent of its length) more accurate than other models, within a factor of two of the measured permeabilities. We discuss some plausible sources of the uncertainties.

  12. TREATMENT OF INORGANIC CONTAMINANTS USING PERMEABLE REACTIVE BARRIERS

    EPA Science Inventory

    Permeable reactive barriers are an emerging alternative to traditional pump and treat systems for groundwater remediation. This technique has progressed rapidly over the past decade from laboratory bench-scale studies to full-scale implementation. Laboratory studies indicate the ...

  13. Research Update from EPA Permeable Parking Lot in Edison, NJ

    EPA Science Inventory

    Communities are increasingly installing green infrastructure stormwater control measures (SCMs) to reduce pollutant loads associated with stormwater runoff. Permeable pavement is a SCM that has limited research on working-scale, side-by-side performance of different pavement sur...

  14. The mitochondrial permeability transition from yeast to mammals

    PubMed Central

    Azzolin, Luca; von Stockum, Sophia; Basso, Emy; Petronilli, Valeria; Forte, Michael A.; Bernardi, Paolo

    2010-01-01

    Regulated permeability changes have been detected in mitochondria across species. We review here their key features, with the goal of assessing whether a “permeability transition” similar to that observed in higher eukaryotes is present in other species. The recent discoveries (i) that treatment with cyclosporin A unmasks an inhibitory site for Pi [Basso et al. (2008) J. Biol Chem. 283, 26307–26311], the classical inhibitor of the permeability transition of yeast; and (ii) that under proper experimental conditions a matrix Ca2+-dependence can be demonstrated in yeast as well [Yamada et al. (2009) Biochim. Biophys. Acta 1787, 1486–1491] suggest that the mitochondrial permeability transition has been conserved during evolution. PMID:20398660

  15. Air permeability and trapped-air content in two soils

    USGS Publications Warehouse

    Stonestrom, D.A.; Rubin, J.

    1989-01-01

    To improve understanding of hysteretic air permeability relations, a need exists for data on the water content dependence of air permeability, matric pressure, and air trapping (especially for wetting-drying cycles). To obtain these data, a special instrument was designed. The instrument is a combination of a gas permeameter (for air permeability determination), a suction plate apparatus (for retentivity curve determination), and an air pycnometer (for trapped-air-volume determination). This design allowed values of air permeability, matric pressure, and air trapping to be codetermined, i.e., determined at the same values of water content using the same sample and the same inflow-outflow boundaries. Such data were obtained for two nonswelling soils. -from Authors

  16. Correlation of Three Techniques for Determining Soil Permeability

    ERIC Educational Resources Information Center

    Winneberger, John T.

    1974-01-01

    Discusses problems of acquiring adequate results when measuring for soil permeability. Correlates three relatively simple techniques that could be helpful to the inexperienced technician dealing with septic tank practices. An appendix includes procedures for valid percolation tests. (MLB)

  17. Porosity, permeability, and their relationship in granite, basalt, and tuff

    SciTech Connect

    Not Available

    1983-04-01

    This report discusses the porosity, storage, and permeability of fractured (mainly crystalline) rock types proposed as host rock for nuclear waste repositories. The emphasis is on the inter-relationships of these properties, but a number of reported measurements are included as well. The porosity of rock is shown to consist of fracture porosity and matrix porosity; techniques are described for determining the total interconnected porosity through both laboratory and field measurement. Permeability coefficient, as obtained by experiments ranging from laboratory to crustal scale, is discussed. Finally, the problem of determining the relationship between porosity and permeability is discussed. There is no simple, all encompassing relationship that describes the dependence of permeability upon porosity. However, two particular cases have been successfully analyzed: flow through a single rough fracture, and flow through isotropic porous rock. These two cases are discussed in this report.

  18. Development of optimized, graded-permeability axial groove heat pipes

    NASA Technical Reports Server (NTRS)

    Kapolnek, Michael R.; Holmes, H. Rolland

    1988-01-01

    Heat pipe performance can usually be improved by uniformly varying or grading wick permeability from end to end. A unique and cost effective method for grading the permeability of an axial groove heat pipe is described - selective chemical etching of the pipe casing. This method was developed and demonstrated on a proof-of-concept test article. The process improved the test article's performance by 50 percent. Further improvement is possible through the use of optimally etched grooves.

  19. Endocannabinoids modulate human blood–brain barrier permeability in vitro

    PubMed Central

    Hind, William H; Tufarelli, Cristina; Neophytou, Maria; Anderson, Susan I; England, Timothy J; O'Sullivan, Saoirse E

    2015-01-01

    Background and Purpose Endocannabinoids alter permeability at various epithelial barriers, and cannabinoid receptors and endocannabinoid levels are elevated by stroke, with potential neuroprotective effects. We therefore explored the role of endocannabinoids in modulating blood–brain barrier (BBB) permeability in normal conditions and in an ischaemia/reperfusion model. Experimental Approach Human brain microvascular endothelial cell and astrocyte co-cultures modelled the BBB. Ischaemia was modelled by oxygen-glucose deprivation (OGD) and permeability was measured by transepithelial electrical resistance. Endocannabinoids or endocannabinoid-like compounds were assessed for their ability to modulate baseline permeability or OGD-induced hyperpermeability. Target sites of action were investigated using receptor antagonists and subsequently identified with real-time PCR. Key Results Anandamide (10 μM) and oleoylethanolamide (OEA, 10 μM) decreased BBB permeability (i.e. increased resistance). This was mediated by cannabinoid CB2 receptors, transient receptor potential vanilloid 1 (TRPV1) channels, calcitonin gene-regulated peptide (CGRP) receptor (anandamide only) and PPARα (OEA only). Application of OEA, palmitoylethanolamide (both PPARα mediated) or virodhamine (all 10 μM) decreased the OGD-induced increase in permeability during reperfusion. 2-Arachidonoyl glycerol, noladin ether and oleamide did not affect BBB permeability in normal or OGD conditions. N-arachidonoyl-dopamine increased permeability through a cytotoxic mechanism. PPARα and γ, CB1 receptors, TRPV1 channels and CGRP receptors were expressed in both cell types, but mRNA for CB2 receptors was only present in astrocytes. Conclusion and Implication The endocannabinoids may play an important modulatory role in normal BBB physiology, and also afford protection to the BBB during ischaemic stroke, through a number of target sites. PMID:25651941

  20. Permeability determinations through the logging of subsurface formation properties

    SciTech Connect

    Herron, M.M.

    1988-09-27

    This patent describes a method for determining the permeability of an earth formation traversed by a borehole, comprising: (a) logging the borehole to determine indications of at least a plurality of predetermined elements in the formation; (b) from the elemental indications, determining a mineralogical content of the formation; (c) determining the porosity of the formation; and (d) determining the permeability of the formation directly as a function of the determined mineralogical content and porosity.

  1. Influence of Subslab Aggregate Permeability of SSV Performance

    SciTech Connect

    Gadgil, A.J.; Bonnefous, Y.C.; Fisk, W.J.; Prill, R.J.; Nematollahi, A.

    1991-09-01

    The effectiveness of the technique of subslab ventilation (SSV) for limiting radon entry into basements was investigated through complementary experimentation and numerical modeling. Determination of the impact of subslab aggregate permeability on SSV performance was a primary objective. Subslab pressure fields resulting from SSV were measured in six well-characterized basements, each with a different combination of soil and aggregate permeability. The relationship between air velocity and pressure gradient within the three types of aggregate installed beneath the basement slabs was measured in the laboratory. A new numerical model of SSV was developed and verified with the field data. This model simulates non-Darcy flow in the aggregate. We demonstrate that non-Darcy effects significantly impact SSV performance. Field data and numerical simulations indicate that increasing the aggregate permeability within the investigated range of 2 x 10{sup -8} m{sup 2} to 3 x 10{sup -7} m{sup 2} substantially improves the extension of the subslab pressure field due to SSV operation. Subslab pressure field extension also improves as soil permeability decreases between 10{sup -9} m{sup 2} and 10{sup -10} m{sup 2}. With a slab-wall gap thickness of 1 mm and the range of aggregate permeability investigated, further reductions in soil permeability do not significantly improve the subslab pressure field extension. Sealing of cracks in the slab and excavation of a small pit where the SSV pipe penetrates the slab also dramatically improve this pressure field extension. A large ratio of aggregate permeability to soil permeability reduces the need for large depressurizations at the SSV pit. Our findings are consistent with the results of prior field studies; however, our understanding of SSV is improved and the dependence of SSV performance on the relevant parameters can now be quantified with the model.

  2. Towards Polymer-Based Capsules with Drastically Reduced Controlled Permeability

    NASA Astrophysics Data System (ADS)

    Andreeva, Daria V.; Sukhorukov, Gleb B.

    Small molecules (dyes, therapeutics, etc.) could be easily handled, stored, delivered, and released by polyelectrolyte capsules. To make the polyelectrolyte capsule more efficient for small molecule encapsulation, capsule permeability should be significantly decreased. Here, we demonstrate the possibility to entrap water-soluble molecular species into polyelectrolyte capsules modified by a low permeable dense polymer (polypyrrole). Possible future areas in PE capsule application as carriers for gases and volatiles in the pharmaceutical, food, and gases industry, agriculture and cosmetology are discussed.

  3. Anisotropic permeabilities evolution of reservoir rocks under pressure

    NASA Astrophysics Data System (ADS)

    Jeremie, D.; Nicolas, G.; Alexandre, D.; Olga, V.

    2006-12-01

    The aim of our study is to measure, to model and to forecast the evolutions of porosity and permeability under anisotropic stresses representative of hydrocarbon reservoir conditions. Reservoir field exploitation induces a decrease of the pore pressure, hence modifying the effective stress-state at the reservoir scale. To optimize production and recovery rates of the reservoir it is of fundamental interest to understand all the physical and mechanical evolutions of the host-rock and their influence on transport properties. In the case of weakly consolidated reservoirs the variations of stresses are modest, yet they can induce significant porosity and permeability changes due to their high compressibility. In the case of deeply buried and consolidated reservoirs the stress variations might be pronounced enough to influence flow properties as well. Because of reservoir boundaries conditions, the fluid pressure drop influences essentially the vertical stress. The recovery rate is a function of horizontal permeability. In order to understand how the anisotropic stress-states induced during production may influence the transport properties experiments must be designed to measure simultaneously both horizontal and vertical permeabilities under deviatoric stresses. For this purpose we developed a specific triaxial cell operating in conditions representative of the field conditions. Preliminary results obtained with low permeability sandstones allowed a coupled observation of deformation and directional permeability evolution. Because of complex geometrical conditions the results required numerical interpretations. A finite-element inversion of our data allowed the determination of the complete permeability tensor. In addition the study aims on the identification of the microphysical mechanics that induce the pore scale microstructural evolution, which is ultimately responsible of the permeability decrease. For this purpose we used synthetic hot-pressed calcite

  4. Resistin increases monolayer permeability of human coronary artery endothelial cells.

    PubMed

    Jamaluddin, Md Saha; Yan, Shaoyu; Lü, Jianming; Liang, Zhengdong; Yao, Qizhi; Chen, Changyi

    2013-01-01

    Resistin has been linked to obesity, insulin resistance, atherosclerosis, and the development of cardiovascular disease. Nevertheless, the effects and the molecular mechanisms of resistin on endothelial permeability, a key event in the development of atherosclerosis, inflammation, and vascular disease, are largely unknown. In order to determine the effect of resistin on endothelial permeability, human coronary artery endothelial cells (HCAECs) were treated with clinically relevant concentrations of resistin and the endothelial permeability was measured using the Transwell system with a Texas-Red-labeled dextran tracer. The permeability of HCAEC monolayers treated with resistin (80 ng/mL) was 51% higher than the permeability of control monolayers (P<0.05). The mRNA levels of tight junction proteins zonula occludens-1 (ZO-1) and occludin in resistin-treated cells were 37% and 42% lower, respectively, than the corresponding levels in untreated cells. The protein levels of these molecules in resistin-treated cells were significantly reduced by 35% and 37%, respectively (P<0.05), as shown by flow cytometry and Western blot analysis. Superoxide dismutase (SOD) mimetic MnTBAP effectively blocked the resistin-mediated reduction of ZO-1 and occludin levels in HCAECs. In addition, superoxide anion production was increased from 21% (untreated cells) to 55% (cells treated with 40 ng/mL resistin), and 64% (resistin, 80 mg/mL) (P<0.05). The natural antioxidant Ginkgolide A effectively inhibited resistin-induced increase in permeability and the increase in superoxide anion production in HCAECs. Furthermore, resistin treatment significantly activated p38 MAPK, but not ERK1/2. Pretreatment of HCAECs with a p38 inhibitor effectively blocked resistin-induced permeability. These results provide new evidence that resistin may contribute to the vascular lesion formation via increasing endothelial permeability through the mechanism of oxidative stress and the activation of p38 MAPK. PMID

  5. Resistin Increases Monolayer Permeability of Human Coronary Artery Endothelial Cells

    PubMed Central

    Jamaluddin, Md Saha; Yan, Shaoyu; Lü, Jianming; Liang, Zhengdong; Yao, Qizhi; Chen, Changyi

    2013-01-01

    Resistin has been linked to obesity, insulin resistance, atherosclerosis, and the development of cardiovascular disease. Nevertheless, the effects and the molecular mechanisms of resistin on endothelial permeability, a key event in the development of atherosclerosis, inflammation, and vascular disease, are largely unknown. In order to determine the effect of resistin on endothelial permeability, human coronary artery endothelial cells (HCAECs) were treated with clinically relevant concentrations of resistin and the endothelial permeability was measured using the Transwell system with a Texas-Red-labeled dextran tracer. The permeability of HCAEC monolayers treated with resistin (80 ng/mL) was 51% higher than the permeability of control monolayers (P<0.05). The mRNA levels of tight junction proteins zonula occludens-1 (ZO-1) and occludin in resistin-treated cells were 37% and 42% lower, respectively, than the corresponding levels in untreated cells. The protein levels of these molecules in resistin-treated cells were significantly reduced by 35% and 37%, respectively (P<0.05), as shown by flow cytometry and Western blot analysis. Superoxide dismutase (SOD) mimetic MnTBAP effectively blocked the resistin-mediated reduction of ZO-1 and occludin levels in HCAECs. In addition, superoxide anion production was increased from 21% (untreated cells) to 55% (cells treated with 40 ng/mL resistin), and 64% (resistin, 80 mg/mL) (P<0.05). The natural antioxidant Ginkgolide A effectively inhibited resistin-induced increase in permeability and the increase in superoxide anion production in HCAECs. Furthermore, resistin treatment significantly activated p38 MAPK, but not ERK1/2. Pretreatment of HCAECs with a p38 inhibitor effectively blocked resistin-induced permeability. These results provide new evidence that resistin may contribute to the vascular lesion formation via increasing endothelial permeability through the mechanism of oxidative stress and the activation of p38 MAPK. PMID

  6. The mitochondrial permeability transition from yeast to mammals.

    PubMed

    Azzolin, Luca; von Stockum, Sophia; Basso, Emy; Petronilli, Valeria; Forte, Michael A; Bernardi, Paolo

    2010-06-18

    Regulated permeability changes have been detected in mitochondria across species. We review here their key features, with the goal of assessing whether a "permeability transition" similar to that observed in higher eukaryotes is present in other species. The recent discoveries (i) that treatment with cyclosporin A (CsA) unmasks an inhibitory site for inorganic phosphate (Pi) [Basso, E., Petronilli, V., Forte, M.A. and Bernardi, P. (2008) Phosphate is essential for inhibition of the mitochondrial permeability transition pore by cyclosporin A and by cyclophilin D ablation. J. Biol. Chem. 283, 26307-26311], the classical inhibitor of the permeability transition of yeast and (ii) that under proper experimental conditions a matrix Ca(2+)-dependence can be demonstrated in yeast as well [Yamada, A., Yamamoto, T., Yoshimura, Y., Gouda, S., Kawashima, S., Yamazaki, N., Yamashita, K., Kataoka, M., Nagata, T., Terada, H., Pfeiffer, D.R. and Shinohara Y. (2009) Ca(2+)-induced permeability transition can be observed even in yeast mitochondria under optimized experimental conditions. Biochim. Biophys. Acta 1787, 1486-1491] suggest that the mitochondrial permeability transition has been conserved during evolution. PMID:20398660

  7. Hybrid green permeable pave with hexagonal modular pavement systems

    NASA Astrophysics Data System (ADS)

    Rashid, M. A.; Abustan, I.; Hamzah, M. O.

    2013-06-01

    Modular permeable pavements are alternatives to the traditional impervious asphalt and concrete pavements. Pervious pore spaces in the surface allow for water to infiltrate into the pavement during rainfall events. As of their ability to allow water to quickly infiltrate through the surface, modular permeable pavements allow for reductions in runoff quantity and peak runoff rates. Even in areas where the underlying soil is not ideal for modular permeable pavements, the installation of under drains has still been shown to reflect these reductions. Modular permeable pavements have been regarded as an effective tool in helping with stormwater control. It also affects the water quality of stormwater runoff. Places using modular permeable pavement has been shown to cause a significant decrease in several heavy metal concentrations as well as suspended solids. Removal rates are dependent upon the material used for the pavers and sub-base material, as well as the surface void space. Most heavy metals are captured in the top layers of the void space fill media. Permeable pavements are now considered an effective BMP for reducing stormwater runoff volume and peak flow. This study examines the extent to which such combined pavement systems are capable of handling load from the vehicles. Experimental investigation were undertaken to quantify the compressive characteristics of the modular. Results shows impressive results of achieving high safety factor for daily life vehicles.

  8. Permeability controls in the Santana Tuff, Trans-Pecos Texas

    SciTech Connect

    Smyth, R.C.; Sharp, J.M. Jr. . Dept. of Geological Sciences)

    1993-02-01

    The Santana Tuff is a poorly to densely welded rhyolitic ash-flow tuff that erupted from the Sierra Rica caldera complex in Chihuahua, Mexico, 27.8 m.y. ago. The portion of the Santana Tuff examined in this study crops out over a 125-km[sup 2] area in the Big Bend Ranch State Natural Area in Trans-Pecos Texas. A review of recent literature has revealed the need to incorporate realistic values for permeability due to fracture spacing into groundwater models. Permeability/porosity relationship for fracture skins and unaltered tuff are significant to problems of solute transport. Permeability measurements of tuff samples vary over four orders of magnitude. The most densely welded samples have the lowest permeability. The least densely welded ones have the highest permeability. However, effective permeabilities of the differentially welded layers are quite different if fractures are considered. The spacing of cooling fractures in poorly to densely welded layers of the Santana Tuff also varies considerably. Degree of welding of the different Santana Tuff units has been quantified by length-to-width ratios (flattening) of pumice fragments. Lognormally distributed fracture spacing measurements correlate directly with the degree of welding. Rose diagrams and stereonets indicate that fracture orientations are not always random, as might be inferred from a cooling origin, but may have preferred orientation patterns.

  9. Bath osmolality: effect on water permeability of epithelial tissue.

    PubMed

    Lau, Y T; Parsons, R H; Feeney, G A; Walker, K L

    1982-03-01

    When hyperosmotic gradients from 100 to 500 mosM are used to produce a water flux, the water permeability of live and potassium cyanide (KCN)-poisoned frog skin decreases with increasing osmotic gradients. In addition, as the total bath osmolality (corium + epithelial) increases there is a reduction in tissue water. Examination of the tissue cellular and extracellular compartments shows that cell shrinkage caused by the increasing hyperosmolality of the bathing medium correlates with the decrease in osmotic permeability. When the bath osmolality is held constant and cell volume decreases, there is a decrease in the water permeability. High potassium in the external bathing medium causes cell swelling that is associated with an increase in water permeability. These data support the hypothesis that a number of conditions known to affect the water permeability of frog skin do so partly or wholly as a result of a change in the cell volume, which either directly or indirectly alters the osmotic permeability of a rate limiting barrier, possibly the cell membrane. PMID:6801996

  10. Influence of Relict Joints on Permeability of Residual Soil

    NASA Astrophysics Data System (ADS)

    Talib, Z. A.; Kassim, A.; Yunusa, G. H.

    2016-07-01

    Weathering process of granitic material results in the formation of relict joint in lateritic layer of the weathering profile. The number and arrangements of the relict joints affects the permeability of the residual soil which invariably affects water flow and suction distribution in the residual soil. Although the permeability of residual soil without a relict joint can be determined using standard permeability test, it is difficult to be measured when a relict joint is incorporated due to limitation of size and area of the standard equipment. Hence, modified permeability test equipment is introduced in this study. Two arrangement of the relict joint in the equipment were considered. In the first arrangement one relict joint with various spacing were tested while the orientation and spacing of the relict joint were tested using two relict joints in the second arrangement. The results obtained shows that the permeability of the residual soil due to one and two relict joint varies by two orders of magnitude. Therefore, the number and spacing of relict joints modified the permeability of residual soil.

  11. Regulation of AQP0 water permeability is enhanced by cooperativity.

    PubMed

    Németh-Cahalan, Karin L; Clemens, Daniel M; Hall, James E

    2013-03-01

    Aquaporin 0 (AQP0), essential for lens clarity, is a tetrameric protein composed of four identical monomers, each of which has its own water pore. The water permeability of AQP0 expressed in Xenopus laevis oocytes can be approximately doubled by changes in calcium concentration or pH. Although each monomer pore functions as a water channel, under certain conditions the pores act cooperatively. In other words, the tetramer is the functional unit. In this paper, we show that changes in external pH and calcium can induce an increase in water permeability that exhibits either a positive cooperativity switch-like increase in water permeability or an increase in water permeability in which each monomer acts independently and additively. Because the concentrations of calcium and hydrogen ions increase toward the center of the lens, a concentration signal could trigger a regulatory change in AQP0 water permeability. It thus seems plausible that the cooperative modes of water permeability regulation by AQP0 tetramers mediated by decreased pH and elevated calcium are the physiologically important ones in the living lens. PMID:23440275

  12. Permeability of fault gouge under confining pressure and shear stress.

    USGS Publications Warehouse

    Morrow, C.A.; Shi, L.Q.; Byerlee, J.D.

    1984-01-01

    The permeability of both clay-rich and non-clay gouges, as well as several pure clays, was studied as a function of confining pressures from 5 to 200 MPa and shear strain to 10. Permeability ranged over 4 orders of magnitude, from around 10-22 to 10-18 m2 (1 darcy = 0.987 X 10-12 m2). Grain size was an important factor in determining permeability, particularly for the clay-rich samples. The permeabilities of the non-clay samples were not significantly different than those of the clays. Strength of the saturated samples under drained (low pore pressure) conditions did not correlate with high or low permeability. However, the low permeabilities of these gouges could be a factor in the measured low shear stresses along fault regions if excess pore pressures were created as a result of shearing or compaction, and this pressure was unable to dissipate through a thick section of the material.-from Authors

  13. Evolution of permeability and induced seismicity within fractured reservoirs

    NASA Astrophysics Data System (ADS)

    Izadi, Ghazal

    Fractured in geologic media, advective transport, heat transfer and chemical transport can change the porosity during short- to long-term fluid circulation that results from changes in mineral volume fractions. The porosity-permeability correlation in geologic media can be complex and depends on several factors such as fracture size distribution, fracture orientations, fracture network connectivity and in situ stresses, among others. Within fractured reservoirs under geothermal conditions, coupling between fluid transport, mechanical response, heat transfer and chemical reactions may change the permeability and influence the induced seismicity both during short-term reservoir stimulation and long-term production. During short-term stimulation, rapid enhancement of fracture permeability occurs as a result of circulating fluid through these fracture networks. During long-term production, hydraulic and thermal effects both contribute to the reactivation of the natural fracture networks and that also enhances the reservoir permeability. During the reactivation of pre-existing fractures due to hydraulic transport and mechanical deformation, seismic events occur when fluid circulates between the injection and production wells with a large number of high magnitude events associated with the initiation of the reservoir stimulation. Determining dominant behaviors that control the enhancement of permeability and the triggering of induced seismicity is the main focus of this work. This dissertation examines the role of coupled thermal, hydraulic, mechanical and chemical effects on various fracture networks in promoting the failure of pre-existing fractures and their influence on the evolution of seismicity and of permeability. (Abstract shortened by UMI.).

  14. The diffusion-active permeable reactive barrier

    NASA Astrophysics Data System (ADS)

    Schwarz, Alex O.; Rittmann, Bruce E.

    2010-03-01

    Using the biogeochemical model CCBATCH, which we expanded to include transport processes, we study a novel approach for the treatment of aquifers contaminated with toxic concentrations of metals, the diffusion-active permeable reactive barrier (DAPRB), which is based on generation of sulfide by Sulfate Reducing Bacteria (SRB) as the groundwater moves through a layered treatment zone. In the DAPRB, layers of low conductivity (low-K) containing reactive materials are intercalated between layers of high conductivity (high-K) that transport the groundwater across the barrier. Because diffusion dominates transport in the reactive layers, microbial communities can take advantage there of the chemical-gradient mechanism for protection from toxicants. The ideal sulfidic DAPRB design includes particulate organic matter (POM) and solid sulfate mineral inside the reactive (low-K) layer. This leads to sulfate reduction and the formation of sulfide ligands that complex with toxic metals, such as Zn 2+ in the high-K layer. We perform a theoretical biogeochemical analysis of the ideal configuration of a DAPRB for treatment of Zn-contaminated groundwater. Our analysis using the expanded CCBATCH confirms the gradient-resistance mechanism for bio-protection, with the ZnS bio-sink forming at the intersection of the Zn and sulfide plumes inside the high-K layers of the DAPRB. The detailed DAPRB analysis also shows that total alkalinity and pH distributions are representative footprints of the two key biogeochemical processes taking place, sulfidogenesis and Zn immobilization as sulfide mineral. This is so because these two reactions consume or produce acidic hydrogen and alkalinity. Additionally, because Zn immobilization is due to ZnS mineral precipitation, the ZnS mineral distribution is a good indicator for the bio-sink. Bio-sinks are located for the most part within the high-K layers, and their exact position depends on the relative magnitude of metal and sulfide fluxes. Finally

  15. Transverse Chemotactic Migration of Bacteria from High to Low Permeability Regions in a Dual Permeability Porous Microfluidic Device

    NASA Astrophysics Data System (ADS)

    Singh, R.; Olson, M. S.

    2011-12-01

    Low permeability regions sandwiched between high permeability regions such as clay lenses are difficult to treat using conventional treatment methods. Trace concentrations of contaminants such as non-aqueous phase liquids (NAPLs) remain trapped in these regions and over the time diffuse out into surrounding water thereby acting as a long term source of groundwater contamination. Bacterial chemotaxis (directed migration toward a contaminant source), may be helpful in enhancing bioremediation of such contaminated sites. This study is focused on simulating a two-dimensional dual-permeability groundwater contamination scenario using microfluidic devices and evaluating transverse chemotactic migration of bacteria from high to low permeability regions. A novel bi-layer polydimethylsiloxane (PDMS) microfluidic device was fabricated using photolithography and soft lithography techniques to simulate contamination of a dual- permeability region due to leakage from an underground storage tank into a low permeability region. This device consists of a porous channel through which a bacterial suspension (Escherchia Coli HCB33) is flown and another channel for injecting contaminant/chemo-attractant (DL-aspertic acid) into the porous channel. The pore arrangement in the porous channel contains a 2-D low permeability region surrounded by high permeability regions on both sides. Experiments were performed under chemotactic and non-chemotactic (replacing attractant with buffer solution in the non porous channel) conditions. Images were captured in transverse pore throats at cross-sections 4.9, 9.8, and 19.6 mm downstream from the attractant injection point and bacteria were enumerated in the middle of each pore throat. Bacterial chemotaxis was quantified in terms of the change in relative bacterial counts in each pore throat at cross-sections 9.8 and 19.6 mm with respect to counts at the cross-section at 4.9 mm. Under non-chemotactic conditions, relative bacterial count was observed

  16. Relating tortuosity and permeability in microfractured and unfractured porous media

    NASA Astrophysics Data System (ADS)

    Tokan-Lawal, A.; Wang, W.; Prodanovic, M.

    2012-12-01

    Permeability estimates are key to any subsurface flow prediction. Several methods are available for estimating (relative) permeability either on Darcy scale (lab measurements) or on pore scale (numerical flow simulation, assuming pore space geometry is known). However, relative permeability measurements in particular can be time consuming, and there is a benefit in having a fast estimate. Thus, a number of permeability estimates are available based on the some known porous medium parameters. The famous Carman Kozeny (1937) model represents the pores as parallel tubes of length equal to the sample length and of a range of radii. This single phase permeability model developed for packings of equal spherical grains relates the absolute permeability to the tortuosity of the medium. Fractures or fracture networks, on the other hand, do not lend themselves to an analytical description akin to pores spaces in-between a packing of spheres. Thus far, the study of flow in fractures has for the most part been limited to fractures in rock with impermeable fractures. The simplest models, such as the cubic law, relate fracture permeability to its average aperture and model fracture as parallel planes which are insufficient to extend to multiphase displacement. In this study, we focus on correlating permeability with geometric tortuosity of both pore space and individual fluid phases for a wide variety of homogeneous as well as microfractured porous samples. We use a combination of lattice-Boltzmann simulation and the level set method based progressive-quasistatic (LSMPQS) algorithm to characterize the capillary dominated flow properties (capillary pressure-saturation and relative permeability-saturation relationships) of the matrix, and when present, the fracture, in samples of different compositions. At the same time, we use image analysis tools to characterize the connectivity and tortuosity of the pore space, as well as individual fluid phases at different saturations

  17. Quantitation of small intestinal permeability during normal human drug absorption

    PubMed Central

    2013-01-01

    Background Understanding the quantitative relationship between a drug’s physical chemical properties and its rate of intestinal absorption (QSAR) is critical for selecting candidate drugs. Because of limited experimental human small intestinal permeability data, approximate surrogates such as the fraction absorbed or Caco-2 permeability are used, both of which have limitations. Methods Given the blood concentration following an oral and intravenous dose, the time course of intestinal absorption in humans was determined by deconvolution and related to the intestinal permeability by the use of a new 3 parameter model function (“Averaged Model” (AM)). The theoretical validity of this AM model was evaluated by comparing it to the standard diffusion-convection model (DC). This analysis was applied to 90 drugs using previously published data. Only drugs that were administered in oral solution form to fasting subjects were considered so that the rate of gastric emptying was approximately known. All the calculations are carried out using the freely available routine PKQuest Java (http://www.pkquest.com) which has an easy to use, simple interface. Results Theoretically, the AM permeability provides an accurate estimate of the intestinal DC permeability for solutes whose absorption ranges from 1% to 99%. The experimental human AM permeabilities determined by deconvolution are similar to those determined by direct human jejunal perfusion. The small intestinal pH varies with position and the results are interpreted in terms of the pH dependent octanol partition. The permeability versus partition relations are presented separately for the uncharged, basic, acidic and charged solutes. The small uncharged solutes caffeine, acetaminophen and antipyrine have very high permeabilities (about 20 x 10-4 cm/sec) corresponding to an unstirred layer of only 45 μm. The weak acid aspirin also has a large AM permeability despite its low octanol partition at pH 7.4, suggesting

  18. Saturated permeability measurements on pumice and welded-tuffaceous materials

    SciTech Connect

    Reda, D.C.; Hadley, G.R.

    1985-12-31

    An experimental apparatus was designed and built to allow water-saturated permeabilities as low as 10{sup -18} m{sup 2} to be measured on cores of diameter 5 cm and length 10 cm under steady-state flow conditions. This same apparatus can also be utilized in a transient (pressure-decay) mode in order to measure permeabilities several orders of magnitude lower than the steady-state limit. Tests were conducted on samples of pumice, fractured welded tuff, and welded tuff, representing a permeability range of seven orders of magnitude. Based on present measurements and calculations, the following results were obtained: Liquid-saturated permeability of the pumice core from Mount St. Helens was 2.76 x 10{sup -12} m{sup 2}; the corresponding Ergun constant was 4.43 x 10{sup 11} kg/m{sup 4}. The ultimate compressive strength of this material was found to be greater than 1.8 MPa, but less than 3.6 MPa; liquid-saturated permeability of the unfractured welded-tuff core was 5.6 x 10{sup -19} m{sup 2}; liquid-saturated permeability for the fractured welded-tuff core was found to decay to 2 x 10{sup -18} m{sup 2} after long-time-scale exposures to continuous-flow and applied-load conditions, independent of the initial fracture state (open vs closed); with an initially closed (naturally existing) fracture, core permeability decreased by a factor of about 2 over a 200-h test period; with an initially open fracture, core permeability decreased by a factor of about 4 under the influence of a comparable load-time history to that experienced in the natural-fracture test; final core permeability was found to be reduced by an order of magnitude from its initial level during a total 700-h test period; and the final effective hydraulic fracture aperture was calculated to be 10{sup -6} m for both tests on the fractured welded-tuff core; the final effective fracture permeability was calculated to be 10{sup -13} m{sup 2}, five orders of magnitude greater than the matrix-material prmeability

  19. Evaluation of permeable and non-permeable tritium in normal condition in a fusion reactor

    NASA Astrophysics Data System (ADS)

    Marta, V.; A, S. Luis; Manuel, P. J.

    2008-05-01

    The tritium cycle, technologies of process and control of the tritium in the plant will constitute a fraction of the environmental impact of the first generation of DT fusion reactors. The efforts of conceptual development of the tritium cycle are centered in the Internal Regenerator Cycle. The tritium could be recovered from a flow of He gas, or directly from solid breeder. The limits of transfers to the atmosphere are assumed ~ 1 gr-T/a (~20 Ci/a) (without species distinction). In the case of ITER, for example, we have global demands of control of 5 orders of magnitude have been demonstrated at experimental level. The transfer limits determine the key parameters in tritium Cycle (HT, HTO, as dominant, and T2, T2O as marginal). Presently, the transfer from the cycle to the environment is assumed through the exchange system of the power plant (primary to secondary). That transport is due to the permeation through HT, T2, or leakage to the coolant in the primary system. It is key the chemical optimitation in the primary system, that needs to be reanalyzed in terms of radiological impact both for permeable, HT, T2, and non-permeable HTO, T2O. It is necessary considered the pathway of tritium from the reactor to the atmosphere, these processes are modelled adequately. Results of the assessments were early and chronic doses which have been evaluated for the Most Exposed Individual at particular distance bands from the release point. The impact evaluations will be performed with the computational tools (NORMTRI), besides national regulatory models, internationally accepted computer these code for dosimetric evaluations of tritiated effluents in operational conditions.

  20. Some Recent Laboratory Measurements of Fault Zone Permeability

    NASA Astrophysics Data System (ADS)

    Morrow, C. A.; Lockner, D. A.

    2005-12-01

    The permeability of fault zone material is key to understanding fluid circulation and the role of pore fluids in earthquake generation and rupture dynamics. Permeability results of core samples from several scientific drillholes are presented, including new results from the SAFOD drillsite in California and the Chelungpu Fault in Taiwan. Permeability values at simulated in situ pressures range from 10-18 to 10-23 m2, a broad range reflecting differences in rock type, proximity to the fault (i.e., fault core, damage zone or country rock), and degree of interseismic healing and sealing. In addition to these natural characteristics, stress-relief and thermal cracking damage resulting from core retrieval will tend to increase the permeability of some of the deepest crystalline rock samples, although testing under in situ conditions can reduce these errors. Recently active fault rocks, with an interconnected network of fractures, tend toward the higher end of the permeability range, whereas fault rocks that have had time to heal through hydrothermal processes tend to have lower permeabilities. In addition, the permeability of borehole-derived core samples was found to be more sensitive to applied pressure than equivalent rocks obtained from surface outcrops because of weathering and other processes. Thus, permeability values of surface samples can not be adequately extrapolated to depth, highlighting the importance of deep drilling studies in determining in situ transport properties. Permeability studies also reveal the storage capacity of the fault rocks, an important parameter in the determination of excess fluid pressure potential. Storage capacity was found to be 10-10 to 10-11/Pa in the Chelungpu Fault cores. Typical down-hole permeability measurements are generally 1-2 orders of magnitude higher than laboratory-derived values because they sample joints and fractures in the damage zone that are larger in scale than the core samples. Consequently, most fluid flow at

  1. Permeability evolution as a result of fluid-rock interaction

    NASA Astrophysics Data System (ADS)

    Astakhov, Dmitriy Konstantinovich

    2000-10-01

    Fluid-rock interaction plays a critical role in the evolution of rock permeability. Among the most important engineering applications are flow of hydrocarbons in petroleum reservoirs, thermal energy extraction, water supply exploration, and toxic and radioactive waste management. Important natural examples include multiple dikes and sheeted intrusions, natural hydraulic fracturing, water circulation in the oceanic crust, and ore deposits formation. In this thesis, new effects associated with stress and temperature dependent permeability of fractured rock were studied. The conducted asymptotic and numerical analysis supported by field and laboratory observations resulted in better understanding of these phenomena and useful recommendations for science and engineering. In particular, the evolution of permeability as a result of the fluid-rock interaction was considered for hydraulic fracturing, fluid flow through jointed layered rocks, and water circulation in seafloor hydrothermal systems. It was shown that in all three cases fluid-rock interaction plays a critical role and must be taken into account by accurately computing changes of fracture apertures. It was also shown that elastic interaction between the segments significantly affects multisegmented hydraulic fracture dimensions and driving pressure and can alter the permeability of jointed layered rocks by orders of magnitude. Fracture closure due to thermal stresses can dramatically reduce water flow through the oceanic crust changing the regime of heat transfer near mid-oceanic ridges and the temperature of the water discharging from the hydrothermal vents. Fracture closure by internal fluid pressure---an effect never previously reported---was found in the study of parallel, closely located fractures. Asymptotic formula that is simple but accurate for all possible parameter ranges was suggested for the permeability of parallel joint sets. These findings may have a significant impact on hydraulic fracture

  2. The porous medium permeability and effective diffusion coefficient direct correlation

    NASA Astrophysics Data System (ADS)

    Markicevic, Bojan

    2012-11-01

    Dimensionless analysis of a momentum and mass transport in the homogeneous porous medium reveals that the permeability and effective to the molecular diffusion coefficient ratio can be expressed as a function of medium pore and throat sizes and two additional geometrical scales. These two scales, each one pertinent to the momentum and mass transport, respectively, are referred to as permeability and diffusivity characteristic scales. Based on these findings, it can be shown that the medium permeability and effective diffusivity can be correlated, and, at the same time, that one microscopic scale needs to be known in this correlation. The same is implied from the Katz-Thompson formula - which correlates the permeability, effective diffusivity, and breakthrough capillary pressure length scale. We recast the correlation developed into the Katz-Thompson formula form, showing how corresponding members are related. It turns out that the coefficient from the Katz-Thompson formula is equal to the ratio of the permeability to diffusivity characteristic length scales, and it is indeed constant for the homogeneous media. As porous media are heterogeneous materials, the analysis is extended onto such materials using heterogeneous capillary networks. The networks with the uniform, normal and log-normal pore size distribution functions are generated, where the networks are sufficiently large to obtain small variations in permeability and effective diffusivity for pore size distribution set. For such stochastically homogeneous media, the effective pore size averages are used in calculating the permeability and effective diffusivity showing the true nature of the coefficient in the Katz-Thompson formula.

  3. Origin and permeability of deep ocean salts

    NASA Astrophysics Data System (ADS)

    Hovland, M.; Rueslåtten, H.

    2009-04-01

    Large, buried salt bodies occur in numerous offshore rift-related sedimentary basins, worldwide. For most practical purposes, the conventional evaporite (solar evaporation of seawater) theory is adequate for explaining these occurrences. However, a new model for their formation has now been published (Hovland et al., 2006; 2007, 2008). This model relies on the properties of supercritical water, a fluid which does not dissolve salt (within specific temperature and pressure ranges). The model predicts that some of the large volumes of salt occurring underground in the Red Sea and also in the Mediterranean Sea, formed by forced hydrothermal circulation of seawater down to depths where it became superctical (i.e., temperatures above 405°C, and pressures above 300 bars). Thus, salt precipitated under-ground and filled up cracks and crevices and also formed massive accumulations, which partly flowed upwards as dense, hot brines, precipitating more solid salts upon cooling. In addition, Holness and Lewis (1997) have shown experimentally that salt bodies subjected to high pressures and elevated temperatures, acquire a permeability comparable to sand. This is because the crystalline structure of salt (halite) attains dihedral angles between salt crystals less than 60° at higher temperatures and pressures, allowing water to form continuous strings around all salt crystals. This allows hot dense brines to migrate through the salt. Thus, the salt may act as conduits for flow of brines and salt slurries from previously accumulated salt in the subsurface. If these brines reach the sea floor, they can also form brine-pools and layered salt bodies on the sea floor. An IODP Pre-proposal (No. 741-pre) is now actively promoting drilling some targets in order of checking out this new theory against the conventional evaporite model. It is hoped that European scientists will take up this question and actively promote drilling into salt bodies, for example in the Red Sea (The

  4. Theoretical studies of permeability inversion from seismoelectric logs

    NASA Astrophysics Data System (ADS)

    Hu, H.; Guan, W.; Zhao, W.

    2012-04-01

    Permeability is one of the most important parameters for evaluating the level of difficulty in oil and gas exploitation. A quick, continuous and accurate in-situ estimate of reservoir permeability is highly significant. Stoneley wave logs have been used to determine formation permeability (Tang and Cheng, 1996). However, the inversion errors of this method are too big in low-permeability formations, especially in high-porosity and low-permeability formations resulting from the high clay content in pores. In this study, we propose to invert permeability by using the full waveforms of seismoelectric logs with low frequencies. This method is based on the relationship of permeability with the ratio of the electric excitation intensity to the pressure field's (REP) with respect to the Stoneley wave in seismoelectric logs. By solving the governing equations for electrokinetic coupled wavefields in homogeneous fluid-saturated porous media (Pride, 1994), we calculate the full waveforms of the borehole seismoelectric wavefields excited by a point pressure source and investigate frequency-dependent excitation intensities of the mode waves and excitation intensities of the real branch points in seismoelectric logs. It is found that the REP's phase, which reflects the phase discrepancy between the Stoneley-wave-induced electric field and the acoustic pressure, is sensitive to formation permeability. To check the relation between permeability and REP's phase qualitatively, an approximate expression of the tangent of the REP's argument is derived theoretically as tan(θEP) ≈-ωc/ω = -φη/ (2πfα ∞ρfκ0), where θEPdenotes the arguments of the REP and their principal value is the REP's phase,ω is the angular frequency,ωc is a critical angular frequency that separates the low-frequency viscous flow from the high-frequency inertial flow, φ is the porosity, α∞ is the tortuosity, κ0 is the Darcy permeability, ρf and η are the density and the viscosity of the pore

  5. Permeability of the San Andreas Fault Zone at Depth

    NASA Astrophysics Data System (ADS)

    Rathbun, A. P.; Song, I.; Saffer, D.

    2010-12-01

    Quantifying fault rock permeability is important toward understanding both the regional hydrologic behavior of fault zones, and poro-elastic processes that affect fault mechanics by mediating effective stress. These include long-term fault strength as well as dynamic processes that may occur during earthquake slip, including thermal pressurization and dilatancy hardening. Despite its importance, measurements of fault zone permeability for relevant natural materials are scarce, owing to the difficulty of coring through active fault zones seismogenic depths. Most existing measurements of fault zone permeability are from altered surface samples or from thinner, lower displacement faults than the SAF. Here, we report on permeability measurements conducted on gouge from the actively creeping Central Deformation Zone (CDZ) of the San Andreas Fault, sampled in the SAFOD borehole at a depth of ~2.7 km (Hole G, Run 4, sections 4,5). The matrix of the gouge in this interval is predominantly composed of particles <10 µm, with ~5 vol% clasts of serpentinite, very fine-grained sandstone, and siltstone. The 2.6 m-thick CDZ represents the main fault trace and hosts ~90% of the active slip on the SAF at this location, as documented by repeated casing deformation surveys. We measured permeability in two different configurations: (1) in a uniaxial pressure cell, in which a sample is placed into a rigid steel ring which imposes a zero lateral strain condition and subjected to axial load, and (2) in a standard triaxial system under isostatic stress conditions. In the uniaxial configuration, we obtained permeabilities at axial effective stresses up to 90 MPa, and in the triaxial system up to 10 MPa. All experiments were conducted on cylindrical subsamples of the SAFOD core 25 mm in diameter, with lengths ranging from 18mm to 40mm, oriented for flow approximately perpendicular to the fault. In uniaxial tests, permeability is determined by running constant rate of strain (CRS) tests up

  6. Permeability Modification Using a Reactive Alkaline-Soluble Biopolymer

    SciTech Connect

    Snadra L. Fox; X. Xie; K. D. Schaller; E. P. Robertson; G. A. Bala

    2003-10-01

    Polymer injection has been used in reservoirs to alleviate contrasting permeability zones. Current technology relies on the use of cross-linking agents to initiate gelation. The use of biological polymers are advantageous in that they can block high permeability areas, are environmentally friendly, and have potential to form reversible gels without the use of hazardous cross-linkers. Recent efforts at the Idaho National Engineering and Environmental Laboratory (INEEL) have produced a reactive alkaline-soluble biopolymer from Agrobacterium sp. ATCC no. 31749 that gels upon decreasing the pH of the polymeric solution. The focus of this study was to determine the impact an alkaline-soluble biopolymer can have on sandstone permeability. Permeability modification was investigated by injecting solubilized biopolymer into Berea sandstone cores and defining the contribution of pH, salt, temperature, and Schuricht crude oil on biopolymer gelation. The biopolymer was soluble in KOH at a pH greater than 11.4 and gelled when the pH dropped below 10.8. The Berea sandstone core buffered the biopolymer solution, decreasing the pH sufficiently to form a gel, which subsequently decreased the permeability. The effluent pH of the control cores injected with 0.01 {und M} KOH (pH 12.0) and 0.10{und M} KOH (pH 13.0) decreased to 10.6 and 12.7, respectively. The permeability of the sandstone core injected with biopolymer was decreased to greater than 95% of the original permeability at 25 C in the presence of 2% NaCl, and Schuricht crude oil; however, the permeability increased when the temperature of the core was increased to 60 C. Residual resistance factors as high as 792 were seen in Berea cores treated with biopolymer. The buffering capacity of sandstone has been demonstrated to reduce the pH of a biopolymer solution sufficiently to cause the polymer to form a stable in-situ gel. This finding could potentially lead to alternate technology for permeability modification, thus

  7. Experimental investigation of turbulent flow over a permeable rough wall

    NASA Astrophysics Data System (ADS)

    Kim, T.; Blois, G.; Best, J.; Christensen, K. T.

    2015-12-01

    Permeable walls are encountered in a variety of geophysical flows, including alluvial river beds, canopies and urban environments. Permeable walls possess very different boundary conditions as compared to classic impermeable walls (i.e. the slip condition and penetration of flow into the bed). Permeability allows flow interactions across the wall interface, resulting in notable mass, momentum and energy exchange. Such exchange takes place in the so-called transition layer and often occurs through turbulent flow mechanisms. It is increasingly recognized that turbulence plays a key role in a number of important natural functions, including biogeochemical as well as geomorphological processes. However, the flow physics of the transition layer are still poorly understood due to a lack of quantitative investigation of these permeable systems within which physical and optical access are severely compromised. This is particularly true for state-of-the-art flow measurement techniques such as particle image velocimetry (PIV) that require unaberrated optical access to the measurement locations. To overcome optical limitations, a refractive index matching (RIM) technique was employed herein to gain full optical access to the transition layer. Sodium Iodide aqueous solution (63% by weight and RI ~ 1.496 at 20°C) served as a working fluid, and an acrylic resin (RI ~ 1.499) was chosen for fabricating wall models. Measurements were performed using high-resolution planar PIV in different configurations to characterize the turbulent boundary layer and the transition layer. The wall models comprised uniform spheres packed in a cubic arrangement, and two cases were modeled - impermeable and permeable walls that were both rough. To eliminate the effect of roughness, and thus isolate the effect of permeability, the surface roughness of the two wall models was kept identical. This allowed us to obtain a more meaningful comparison and highlight the impact of wall permeability in natural

  8. Controlling ferrofluid permeability across the blood-brain barrier model

    NASA Astrophysics Data System (ADS)

    Shi, Di; Sun, Linlin; Mi, Gujie; Sheikh, Lubna; Bhattacharya, Soumya; Nayar, Suprabha; Webster, Thomas J.

    2014-02-01

    In the present study, an in vitro blood-brain barrier model was developed using murine brain endothelioma cells (b.End3 cells). Confirmation of the blood-brain barrier model was completed by examining the permeability of FITC-Dextran at increasing exposure times up to 96 h in serum-free medium and comparing such values with values from the literature. After such confirmation, the permeability of five novel ferrofluid (FF) nanoparticle samples, GGB (ferrofluids synthesized using glycine, glutamic acid and BSA), GGC (glycine, glutamic acid and collagen), GGP (glycine, glutamic acid and PVA), BPC (BSA, PEG and collagen) and CPB (collagen, PVA and BSA), was determined using this blood-brain barrier model. All of the five FF samples were characterized by zeta potential to determine their charge as well as TEM and dynamic light scattering for determining their hydrodynamic diameter. Results showed that FF coated with collagen passed more easily through the blood-brain barrier than FF coated with glycine and glutamic acid based on an increase of 4.5% in permeability. Through such experiments, diverse magnetic nanomaterials (such as FF) were identified for: (1) MRI use since they were less permeable to penetrate the blood-brain barrier to avoid neural tissue toxicity (e.g. GGB) or (2) brain drug delivery since they were more permeable to the blood-brain barrier (e.g. CPB).

  9. Calculation of the effective permeability of saturated random porous media

    NASA Astrophysics Data System (ADS)

    Ostvar, S.; Wood, B. D.; Apte, S.; Liburdy, J.

    2014-12-01

    Estimation of the effective permeability tensor is an essential part of Darcy-scale representations of flow in porous media. The permeability tensor itself is a property of the medium, and depends only on the microscale geometry of the system. Determining the functional relationships between effective permeability (or conductivity in the general sense) and the structure of the medium is an old problem, with the earliest results for ordered porous media dating the 1920's. In this presentation, we report on the results of (1) detailed theory development, and (2) computations for the effective permeability tensor in fully-saturated random sphere packs, with a focus on the computational results. The theory is developed by volume averaging the Stokes equations, and using developing appropriate closures via potential theory, and has been reported on previously. For the computations, we have adopted an immersed boundary method to fully resolve the pore-scale velocity field. From our results, we compute the hydraulic permeability for both ordered and random media, and we compare these results with existing analytical solutions for the hydraulic conductivity in periodic arrays.

  10. Determining permeability of tight rock samples using inverse modeling

    NASA Astrophysics Data System (ADS)

    Finsterle, Stefan; Persoff, Peter

    1997-08-01

    Data from gas-pressure-pulse-decay experiments have been analyzed by means of numerical simulation in combination with automatic model calibration techniques to determine hydrologie properties of low-permeability, low-porosity rock samples. Porosity, permeability, and Klinkenberg slip factor have been estimated for a core plug from The Geysers geothermal field, California. The experiments were conducted using a specially designed permeameter with small gas reservoirs. Pressure changes were measured as gas flowed from the pressurized upstream reservoir through the sample to the downstream reservoir. A simultaneous inversion of data from three experiments performed on different pressure levels allows for independent estimation of absolute permeability and gas permeability which is pressure-dependent due to enhanced slip flow. With this measurement and analysis technique we can determine matrix properties with permeabilities as low as 10-21 m2. In this paper we discuss the procedure of parameter estimation by inverse modeling. We will focus on the error analysis, which reveals estimation uncertainty and parameter correlations. This information can also be used to evaluate and optimize the design of an experiment. The impact of systematic errors due to potential leakage and uncertainty in the initial conditions will also be addressed. The case studies clearly illustrate the need for a thorough error analysis of inverse modeling results.

  11. Direct Optofluidic Measurement of the Lipid Permeability of Fluoroquinolones

    PubMed Central

    Cama, Jehangir; Schaich, Michael; Al Nahas, Kareem; Hernández-Ainsa, Silvia; Pagliara, Stefano; Keyser, Ulrich F.

    2016-01-01

    Quantifying drug permeability across lipid membranes is crucial for drug development. In addition, reduced membrane permeability is a leading cause of antibiotic resistance in bacteria, and hence there is a need for new technologies that can quantify antibiotic transport across biological membranes. We recently developed an optofluidic assay that directly determines the permeability coefficient of autofluorescent drug molecules across lipid membranes. Using ultraviolet fluorescence microscopy, we directly track drug accumulation in giant lipid vesicles as they traverse a microfluidic device while exposed to the drug. Importantly, our measurement does not require the knowledge of the octanol partition coefficient of the drug – we directly determine the permeability coefficient for the specific drug-lipid system. In this work, we report measurements on a range of fluoroquinolone antibiotics and find that their pH dependent lipid permeability can span over two orders of magnitude. We describe various technical improvements for our assay, and provide a new graphical user interface for data analysis to make the technology easier to use for the wider community. PMID:27604156

  12. Direct Optofluidic Measurement of the Lipid Permeability of Fluoroquinolones.

    PubMed

    Cama, Jehangir; Schaich, Michael; Al Nahas, Kareem; Hernández-Ainsa, Silvia; Pagliara, Stefano; Keyser, Ulrich F

    2016-01-01

    Quantifying drug permeability across lipid membranes is crucial for drug development. In addition, reduced membrane permeability is a leading cause of antibiotic resistance in bacteria, and hence there is a need for new technologies that can quantify antibiotic transport across biological membranes. We recently developed an optofluidic assay that directly determines the permeability coefficient of autofluorescent drug molecules across lipid membranes. Using ultraviolet fluorescence microscopy, we directly track drug accumulation in giant lipid vesicles as they traverse a microfluidic device while exposed to the drug. Importantly, our measurement does not require the knowledge of the octanol partition coefficient of the drug - we directly determine the permeability coefficient for the specific drug-lipid system. In this work, we report measurements on a range of fluoroquinolone antibiotics and find that their pH dependent lipid permeability can span over two orders of magnitude. We describe various technical improvements for our assay, and provide a new graphical user interface for data analysis to make the technology easier to use for the wider community. PMID:27604156

  13. Hydrodynamic Forcing Mobilizes Cu in Low-Permeability Estuarine Sediments.

    PubMed

    Xie, Minwei; Wang, Ning; Gaillard, Jean-François; Packman, Aaron I

    2016-05-01

    Overlying hydrodynamics play critical roles in controlling surface-porewater exchanges in permeable sediments, but these effects have rarely been characterized in low-permeability sediments. We conducted a series of laboratory experiments to evaluate the effects of varied hydrodynamic conditions on the efflux of metals from low-permeability estuarine sediments. Two Cu-contaminated sediments obtained from the Piscataqua River were subject to controlled levels of hydrodynamic shear in Gust mesocosms, including episodic sediment resuspension. Overlying water and porewater samples were collected over the course of experiments and analyzed for metal concentrations. The two sediments had similar permeability (∼10(-15) m(2)), but different particle size distributions. Hydrodynamic forcing enhanced the mobilization and efflux of Cu from the coarser-grained sediments, but not the finer-grained sediments. Sediment resuspension caused additional transitory perturbations in Cu concentrations in the water column. Particulate metal concentrations increased significantly during resuspension, but then rapidly decreased to preresuspension levels following cessation of sediment transport. Overall, these results show that the mobility and efflux of metals are likely to be influenced by overlying hydrodynamics even in low-permeability sediments, and these effects are mediated by sediment heterogeneity and resuspension. PMID:27054802

  14. Permeability-increasing effects of low-power light

    NASA Astrophysics Data System (ADS)

    Nemtsev, Igor Z.; Koudryavtsev, N. N.

    1996-01-01

    The actions of physico-chemical mechanisms of low power light, applied in medicine are discussed. The investigations were prepared both in experiment on laboratory animals and in emergency-care clinics, where I worked with physicians as the theory-investigator. In this message I propose the theory of permeability increasing effects of low power light. Proton- permeability increasing effects on membranes go to the bioenergetic mechanism of low power light action. Sodium-permeability increasing effects on excitable membranes go to the reflex mechanism of low power light action. We suppose the medical mechanism of laser irradiation effects on the blood to be connected with water-permeability increasing effects because of blood cell membrane depolarization and shaking. We measured the dependence of red blood cell membrane water-permeability coefficient upon the low power light irradiation wavelength in the range 625 - 645 nm. So it was proved that He-Ne laser irradiation with 633 nm wavelength excites dissolved molecular oxygen from the ground triplet state to the singlet state. Fast relaxation of singlet oxygen to triplet state in water medium near membrane with the time 10-6 sec go to the membrane purification mechanism of low power light action.

  15. Simulating bioclogging effects on dynamic riverbed permeability and infiltration

    NASA Astrophysics Data System (ADS)

    Newcomer, Michelle E.; Hubbard, Susan S.; Fleckenstein, Jan H.; Maier, Ulrich; Schmidt, Christian; Thullner, Martin; Ulrich, Craig; Flipo, Nicolas; Rubin, Yoram

    2016-04-01

    Bioclogging in rivers can detrimentally impact aquifer recharge. This is particularly so in dry regions, where losing rivers are common, and where disconnection between surface water and groundwater (leading to the development of an unsaturated zone) can occur. Reduction in riverbed permeability due to biomass growth is a time-variable parameter that is often neglected, yet permeability reduction from bioclogging can introduce order of magnitude changes in seepage fluxes from rivers over short (i.e., monthly) timescales. To address the combined effects of bioclogging and disconnection on infiltration, we developed numerical representations of bioclogging processes within a one-dimensional, variably saturated flow model representing losing-connected and losing-disconnected rivers. We tested these formulations using a synthetic case study informed with biological data obtained from the Russian River, California, USA. Our findings show that modeled biomass growth reduced seepage for losing-connected and losing-disconnected rivers. However, for rivers undergoing disconnection, infiltration declines occurred only after the system was fully disconnected. Before full disconnection, biologically induced permeability declines were not significant enough to offset the infiltration gains introduced by disconnection. The two effects combine to lead to a characteristic infiltration curve where peak infiltration magnitude and timing is controlled by permeability declines relative to hydraulic gradient gains. Biomass growth was found to hasten the onset of full disconnection; a condition we term `effective disconnection'. Our results show that river infiltration can respond dynamically to bioclogging and subsequent permeability declines that are highly dependent on river connection status.

  16. Intestinal permeability in children/adolescents with functional dyspepsia

    PubMed Central

    2014-01-01

    Background An altered intestinal mucosal barrier has been demonstrated in subsets of patients with IBS and FAP and may be an additional biological factor contributing to symptom generation in children with FD. The objective of this study was to determine if intestinal permeability is increased in children/adolescents with functional dyspepsia (FD) and whether intestinal permeability is correlated with mucosal inflammation and/or symptoms of anxiety or depression in this population. Methods A sugar absorption test was performed in 19 patients with FD and 19 controls. Anxiety and depression were assessed in both groups utilizing a standard questionnaire. In FD patients, duodenal mean and peak mast cell and eosinophil densities were determined. Results Intestinal permeability as measured by the sugar absorption test did not differ between children with FD and controls. In children with FD, there was no correlation between permeability and mast cell density, eosinophil density, anxiety scores, or depression scores, respectively. Conclusions Pediatric FD does not appear to be associated with increased small bowel intestinal permeability, however, there are some limitations to the current study. Trial registration ClinicalTrials.gov; NCT00363597. PMID:24886078

  17. A mechanistic model for permeability evolution in fractured sorbing media

    NASA Astrophysics Data System (ADS)

    Wang, Shugang; Elsworth, Derek; Liu, Jishan

    2012-06-01

    A mechanistic model is presented to represent the evolution of permeability in fractured sorbing media such as coal beds and organic-rich shales. This model accommodates key competing processes of poromechanical dilation and sorption-induced swelling. We show that the significant difference in stiffness between fracture and matrix transforms the composite system from globally unconstrained to locally constrained by the development of a virtual "stiff shell" that envelops the perimeter of a representative elementary volume containing a fracture. It is this transformation that results in swelling-induced permeability reduction at low (sorbing) gas pressures and self consistently allows competitive dilation of the fracture as gas pressures are increased. Importantly, net dilation is shown to require a mismatch in the Biot coefficients of fracture and matrix with the coefficient for the fracture exceeding that for the matrix—a condition that is logically met. Permeability evolution is cast in terms of series and parallel models with the series model better replicating observational data. The model may be cast in terms of nondimensional parameters representing sorptive and poromechanical effects and modulated by the sensitivity of the fracture network to dilation or compaction of the individual fractures. This latter parameter encapsulates the effects of fracture spacing and initial permeability and scale changes in permeability driven by either sorption or poromechanical effects. This model is applied to well-controlled observational data for different ranks of coals and different gases (He, CO2) and satisfactory agreement is obtained.

  18. Desformylgramicidin: a model channel with an extremely high water permeability.

    PubMed Central

    Saparov, S M; Antonenko, Y N; Koeppe, R E; Pohl, P

    2000-01-01

    The water conductivity of desformylgramicidin exceeds the permeability of gramicidin A by two orders of magnitude. With respect to its single channel hydraulic permeability coefficient of 1.1.10(-12) cm(3) s(-1), desformylgramicidin may serve as a model for extremely permeable aquaporin water channel proteins (AQP4 and AQPZ). This osmotic permeability exceeds the conductivity that is predicted by the theory of single-file transport. It was derived from the concentration distributions of both pore-impermeable and -permeable cations that were simultaneously measured by double barreled microelectrodes in the immediate vicinity of a planar bilayer. From solvent drag experiments, approximately five water molecules were found to be transported by a single-file process along with one ion through the channel. The single channel proton, potassium, and sodium conductivities were determined to be equal to 17 pS (pH 2.5), 7 and 3 pS, respectively. Under any conditions, the desformyl-channel remains at least 10 times longer in its open state than gramicidin A. PMID:11053127

  19. The evaluation of rock permeability with streaming current measurements

    NASA Astrophysics Data System (ADS)

    Wang, Jun; Hu, Hengshan; Guan, Wei

    2016-06-01

    Rock permeability is an important parameter for the formation evaluation. In this paper, a new method with streaming current is proposed to determine the sample permeability based on the electrokinetic effects, and is proved by the experimental measurements. Corresponding to this method, we have designed an experimental setup and a test system, then performed the streaming current (potential) and electroosmosis pressure experiments with 23 sandstone samples at 0.05 mol/l NaCl solution. The streaming current (potential) coefficient and electroosmosis pressure coefficient are obtained respectively with the experimental data at low frequencies with AC lock-in technique. The electrokinetic permeabilities are further calculated with these coefficients. The results are consistent well with the gas permeability measured with Darcy's law, which verifies the current method for estimating rock permeability. Our measurements are also analyzed and compared with previous measurements. The results indicate that our method can reflect the essence of electrokinetic effects better and simplify the electrokinetic measurements as well. In addition, we discuss the influences of experimental artefacts (core-holder and confining pressure installation) on the electrokinetic data. The results show that the trough phenomenon, appeared in frequency curves of streaming current (potential) coefficients, is induced by the resonance of the core-holder/vibrator system. This is important for the design of electrokinetic setup and the analysis of low frequency response of the electrokinetic coupling coefficients.

  20. Acetazolamide inhibits osmotic water permeability by interaction with aquaporin-1.

    PubMed

    Gao, Junwei; Wang, Xiaohua; Chang, Yongjie; Zhang, Jianzhao; Song, Qianliu; Yu, Heming; Li, Xuejun

    2006-03-15

    Water channel proteins, known as aquaporins, are transmembrane proteins that mediate osmotic water permeability. In a previous study, we found that acetazolamide could inhibit osmotic water transportation across Xenopus oocytes by blocking the function of aquaporin-1 (AQP1). The purpose of the current study was to confirm the effect of acetazolamide on water osmotic permeability using the human embryonic kidney 293 (HEK293) cells transfected with pEGFP/AQP1 and to investigate the interaction between acetazolamide and AQP1. The fluorescence intensity of HEK293 cells transfected with pEGFP/AQP1, which corresponds to the cell volume when the cells swell in a hyposmotic solution, was recorded under confocal laser fluorescence microscopy. The osmotic water permeability was assessed by the change in the ratio of cell fluorescence to certain cell area. Acetazolamide, at concentrations of 1 and 10muM, inhibited the osmotic water permeability in HEK293 cells transfected with pEGFP/AQP1. The direct binding between acetazolamide and AQP1 was detected by surface plasmon resonance. AQP1 was prepared from rat red blood cells and immobilized on a CM5 chip. The binding assay showed that acetazolamide could directly interact with AQP1. This study demonstrated that acetazolamide inhibited osmotic water permeability through interaction with AQP1. PMID:16480680

  1. Modification in Cay Concrete Properties During Fluid Flow Permeability Measurement

    NASA Astrophysics Data System (ADS)

    Solomon, F.; Ekolu, S. O.

    2015-11-01

    In this paper, two methods consisting of triaxial water permeability and water penetration were used to evaluate the changes occurring in the pores of clay concretes during the tests. Triaxial permeability is generally used for concrete with higher permeability while concretes with very low permeability are suited for the penetration method. Clay concrete specimens of 0 to 40% clay content were used in the study. The concrete mixes had water-to-cement ratios (w/c) of 0.70, 0.75, 0.80, 0.85, and the cementitious content 380 and 450 kg/m3. Results show that concrete gains moisture during wetting at a much faster rate than loses it during subsequent drying. This could be explained by the contribution of suction pressure created upon drying. When water penetration pressure is applied, more water is driven into pore space that could be responsible for changing the network of the voids. Pore structure during drying may certainly be different in size and shape than its form during wetting, leading to a consequent effect on the permeability of the clay concretes. The modification could be one reason why the moisture gain percentage in clay concretes was higher than in normal concretes.

  2. 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).

  3. Controlling ferrofluid permeability across the blood–brain barrier model.

    PubMed

    Shi, Di; Sun, Linlin; Mi, Gujie; Sheikh, Lubna; Bhattacharya, Soumya; Nayar, Suprabha; Webster, Thomas J

    2014-02-21

    In the present study, an in vitro blood–brain barrier model was developed using murine brain endothelioma cells (b.End3 cells). Confirmation of the blood–brain barrier model was completed by examining the permeability of FITCDextran at increasing exposure times up to 96 h in serum-free medium and comparing such values with values from the literature. After such confirmation, the permeability of five novel ferrofluid (FF) nanoparticle samples, GGB (ferrofluids synthesized using glycine, glutamic acid and BSA), GGC (glycine, glutamic acid and collagen), GGP (glycine, glutamic acid and PVA), BPC (BSA, PEG and collagen) and CPB (collagen, PVA and BSA), was determined using this blood–brain barrier model. All of the five FF samples were characterized by zeta potential to determine their charge as well as TEM and dynamic light scattering for determining their hydrodynamic diameter. Results showed that FF coated with collagen passed more easily through the blood–brain barrier than FF coated with glycine and glutamic acid based on an increase of 4.5% in permeability. Through such experiments, diverse magnetic nanomaterials (such as FF) were identified for: (1) MRI use since they were less permeable to penetrate the blood–brain barrier to avoid neural tissue toxicity (e.g. GGB) or (2) brain drug delivery since they were more permeable to the blood–brain barrier (e.g. CPB). PMID:24457539

  4. Influence of relative permeabilities on chemical enhanced oil recovery

    NASA Astrophysics Data System (ADS)

    Destefanis, M. F.; Savioli, G. B.

    2011-05-01

    The main objective of chemical flooding is to mobilize the trapped oil remaining after a secondary recovery by waterflooding. This purpose is achieved by lowering the oil-water interfacial tension and producing partial miscibility between both phases. The chemical partition among phases (phase behavior) influences all other physical properties. In particular, it affects residual saturations determining relative permeability curves. Relative permeabilities rule the flow of each phase through the porous medium, so they play an essential role in oil recovery. Therefore, in this work we study the influence of relative permeabilities on the behavior of a surfactant-polymer flooding for the three different types of phase behavior. This analysis is performed applying the 3D compositional numerical simulator UTCHEM developed at the University of Texas at Austin. From the examples studied, we conclude that the influence of relative permeabilities depends on the type of phase behavior, i.e., as microemulsion relative permeability decreases, oil recovery increases for Types II(+) and III while slightly decreases for Type II(-). Moreover, a better displacement efficiency is observed for Types II(+) and III, because they behave similarly to a miscible displacement.

  5. Similarity & Instability in Flows Over Permeable Layers (Invited)

    NASA Astrophysics Data System (ADS)

    Ghisalberti, M.

    2013-12-01

    Permeable obstructions (such as seagrass meadows) are prevalent in the benthic region of freshwater and coastal environments. Their impact on the near-bed flow, turbulence and vertical transport is profound. Here, I use particle imaging and point velocity measurements in both steady and oscillatory flows to demonstrate three salient features of environmental flows over permeable layers: (1) A framework developed for vegetation canopies has the capacity to predict flow, turbulence and mixing properties over a wide range of permeable layers (from sediment beds to coral reefs to 'urban' canopies to ancient rangeomorph communities). (2) Steady flows are characterized by the development of a Kelvin-Helmholtz-type instability at the interface between the permeable layer and the free flow. These coherent structures dominate vertical mixing at the interface and generate regular oscillations in flow and transport. The height of the permeable layer relative to its drag length scale defines three regimes of obstructed shear flow. (3) Such instability is also observed in oscillatory flow when both the Reynolds and Keulegan-Carpenter numbers exceed threshold values. This is important in the prediction of residence time in ecologically-significant benthic habitats that exist in shallow (and therefore, typically, wave-dominated) coastal regions.

  6. High Temperature Permeability of Carbon Cloth Phenolic Composite

    NASA Technical Reports Server (NTRS)

    Park, O. Y.; Lawrence, T. W.

    2003-01-01

    The carbon fiber phenolic resin composite material used for the RSRM nozzle insulator occasionally experiences problems during operation from pocketing or spalling-like erosion and lifting of plies into the char layer. This phenomenon can be better understood if the permeability of the material at elevated temperatures is well defined. This paper describes an experimental approach to determining high temperature permeability of the carbon phenolic material used as the RSRM nozzle liner material. Two different approaches were conducted independently using disk and bar type specimens with the designed permeability apparatus. The principle of the apparatus was to subject a test specimen to a high pressure differential and a heat supply and to monitor both the pressure and temperature variations resulting from gas penetration through the permeable wall between the two chambers. The bar types, especially designed to eliminate sealing difficulties at a high temperature environment, were directly exposed to real time temperature elevation from 22 C to 260 C during the test period. The disk types were pre-heat treated up to 300 C for 8 hours and cooled to room temperature before testing. Nonlinear variation of downstream pressure at a certain temperature range implied moisture release and matrix pyrolysis. Permeability was calculated using a semi-numerical model of quasi-steady state. The test results and the numerical model are discussed in the paper.

  7. Determination of hydrogen permeability in commercial and modified superalloys

    NASA Technical Reports Server (NTRS)

    Bhattacharyya, S.; Peterman, W.

    1983-01-01

    The results of hydrogen permeability measurements on several iron- and cobalt-base alloys as well as on two long-ranged ordered alloys over the range of 705 to 870 C (1300 to 1600 F) are summarized. The test alloys included wrought alloys N-155, IN 800, A-286, 19-9DL, and 19-9DL modifications with aluminum, niobium, and misch metal. In addition, XF-818, CRM-6D, SA-F11, and HS-31 were evaluated. Two wrought long-range ordered alloys, Ni3Al and (Fe,Ni)3(V,Al) were also evaluated. All tests were conducted at 20.7 MPa pressure in either pure and/or 1% CO2-doped H2 for test periods as long as 133 h. Detailed analyses were conducted to determine the relative permeability rankings of these alloys and the effect of doping, exit surface oxidation, specimen design variations, and test duration on permeability coefficient, and permeation activation energies were determined. The two long-range ordered alloys had the lowest permeability coefficients in pure H2 when compared with the eight commercial alloys and their modifications. With CO2 doping, significant decrease in permeability was observed in commercial alloys--no doped tests were conducted with the long-range ordered alloys.

  8. Permeability profile of poly(alkyl cyanoacrylate) nanocapsules.

    PubMed

    Erdmann, Christian; Mayer, Christian

    2016-09-15

    The permeability profile of poly(alkyl cyanoacrylate) nanocapsules is studied using pulsed-field gradient NMR on a variety of tracer molecules of different size and polarity. In addition, the influence of the surfactant layer and of organic tracer molecules on the capsule membrane permeability for water is examined. The aim of the study is a detailed understanding of the dependencies between molecular properties of a given tracer and its capability to permeate the polymer membrane. As expected, the results clearly show that the capsule membrane permeability depends on the size of the tracer molecule: the exchange rate of polyethylene glycols continuously decreases with increasing chain length. However, the permeation rate also varies with the polarity of the tracer molecule: molecules of lower polarity exchange faster than more polar ones. In turn, the capsule membrane permeability is influenced by added organic compounds. Focusing on water as a characteristic permeate and depending on the type of the additive, the permeability can be varied by almost an order of magnitude, offering an opportunity to reversibly switch the uptake and release properties of the capsules. PMID:27343463

  9. Genetic aspects of intestinal permeability in inflammatory bowel disease.

    PubMed

    Takeuchi, Ken; Maiden, Laurence; Bjarnason, Ingvar

    2004-01-01

    There is a long-standing belief that disruption of the intestinal barrier function may lead to systemic and local intestinal disease. The role of increased intestinal permeability in Crohn's disease is reviewed here. What is not in doubt is that intestinal permeability in patients with Crohn's disease is increased proportional to disease activity; it can be used to predict clinical relapse of disease and prognosis; and a small proportion of first-degree relatives have increased intestinal permeability. This last finding has been subject to much speculation. In particular it has been suggested that it represents a genetically determined abnormality. If so it might play an important pathogenic process in the disease. However this permeability change in relatives does not conform to a classical inheritance pattern and in some studies it is found in the patients' spouses. This suggests an environmental cause for the changes. However proponents of an environmental factor have been singularly inactive in attempting to identify this agent(s). In view of recent research it seems likely that the increased intestinal permeability in relatives of Crohn's patients may be secondary to sub-clinical intestinal inflammation. This inflammation conforms to an inherited additive trait. The genetic basis for this inflammation is being studied. PMID:15669640

  10. Proton/hydroxide conductance and permeability through phospholipid bilayer membranes.

    PubMed Central

    Gutknecht, J

    1987-01-01

    Proton/hydroxide (H+/OH-) permeability of phospholipid bilayers is several orders of magnitude higher than alkali or halide ion permeabilities at pH 7. The objective of this study was to determine the mechanism(s) of H+/OH- conductance and permeability through planar phospholipid bilayer membranes. Membranes were formed from decane solutions of bacterial phosphatidylethanolamine, diphytanoyl phosphatidylcholine, or egg phosphatidylcholine plus cholesterol. At pH 7, H+/OH- conductance (GH/OH) ranged from 2 to 6 nS.cm-2, corresponding to H+/OH- "net" permeabilities of (0.4-1.6) X 10(-5) cm.sec-1. GH/OH was inhibited by serum albumin (fatty acid-free), phloretin, and low pH. GH/OH was increased by chlorodecane, long-chain fatty acids, and voltages greater than 80 mV. Water permeability and GH/OH were not correlated. The results suggest that the H+/OH- charge carrier (i) is primarily anionic, (ii) crosses the membrane via nonpolar pathway(s), and (iii) can be removed from the membrane by "washing" with serum albumin. The simplest explanation is that the phospholipids contain weakly acidic contaminants that act as proton carriers at neutral pH. However, at low pH or in the presence of inhibitors, a "background" GH/OH remains that may be due to other mechanisms. PMID:2819878

  11. System level permeability modeling of porous hydrogen storage materials.

    SciTech Connect

    Kanouff, Michael P.; Dedrick, Daniel E.; Voskuilen, Tyler

    2010-01-01

    A permeability model for hydrogen transport in a porous material is successfully applied to both laboratory-scale and vehicle-scale sodium alanate hydrogen storage systems. The use of a Knudsen number dependent relationship for permeability of the material in conjunction with a constant area fraction channeling model is shown to accurately predict hydrogen flow through the reactors. Generally applicable model parameters were obtained by numerically fitting experimental measurements from reactors of different sizes and aspect ratios. The degree of channeling was experimentally determined from the measurements and found to be 2.08% of total cross-sectional area. Use of this constant area channeling model and the Knudsen dependent Young & Todd permeability model allows for accurate prediction of the hydrogen uptake performance of full-scale sodium alanate and similar metal hydride systems.

  12. Apparatus for providing directional permeability measurements in subterranean earth formations

    DOEpatents

    Shuck, Lowell Z.

    1977-01-01

    Directional permeability measurements are provided in a subterranean earth formation by injecting a high-pressure gas from a wellbore into the earth formation in various azimuthal directions with the direction having the largest pressure drop being indicative of the maximum permeability direction. These measurements are provided by employing an inflatable boot containing a plurality of conduits in registry with a like plurality of apertures penetrating the housing at circumferentially spaced-apart locations. These conduits are, in turn, coupled through a valved manifold to a source of pressurized gas so that the high-pressure gas may be selectively directed through any conduit into the earth formation defining the bore with the resulting difference in the pressure drop through the various conduits providing the permeability measurements.

  13. Experimental investigation of the permeability for unconsolidated porous media

    SciTech Connect

    Lei, S.Y.; Jia, L.Q.; Xia, C.M.; Zheng, G.Y.

    1997-07-01

    A device was constructed to investigate the permeability of unconsolidated media at low flow rate and small pressure drop. The stability and reliability of the device have been verified through repeated experiments on a given porous medium. The experimental investigation on the porous media demonstrated that the permeability-porosity relation is unique for a given medium. Experiments with the narrow screened sands show that conventional hydrodynamics theory and dimension analysis can not be applied satisfactorily in the study of the capillary porous media. For screened sand whose particle size ranges from 0.10mm to 0.45mm and size rate is 1:1.25, the permeability can be estimated from formula k = 4.89 x 10{sup {minus}4} d{sup 1.465} {phi}{sup 4.69} where k and d are limited in m{sup 2} and m, respectively.

  14. Dual-effect laser handpiece for modification of tissue permeability

    NASA Astrophysics Data System (ADS)

    McMillan, Kathleen

    2011-03-01

    A new approach for improving the availability of topically applied drugs by reducing the permeability of dermis has been evaluated. The premise of this work is that photothermal vascular injury will reduce vascular uptake of drug in the dermis. The dermal distribution of two topically applied drugs, 5-fluorouracil and mitomycin C, is calculated, considering molecular diffusion and vascular uptake according to a distributed model, in the presence and absence of vascular injury. Intradermal drug exposures obtained are compared to exposures known to be effective in killing tumor cells. Combining the reduction in dermal permeability with fractional photothermal epidermal ablation to increase epidermal permeability may allow higher drug concentrations to be achieved in the skin. A newly developed laser handpiece for implementing the technique is described.

  15. Estimation of reservoir permeability using gravity change measurements

    SciTech Connect

    Hunt, Trevor M.; Kissling, Warwick M.

    1994-01-20

    Exploitation of a liquid-dominated geothermal system generally results in a transfer of mass that causes measurable changes in gravity. When the rate of mass transfer is controlled by the permeability of the reservoir rocks then analysis of measured gravity changes, using numerical reservoir simulation models, can yield values for reservoir properties. One such case is during the early stages of exploitation, during the formation and expansion of a 2-phase zone. Calculations using MULKOM models show that for Wairakei field the gravity changes associated with permeabilities of 50 and 100 md would be clearly distinguishable (> 50 microgal) in less than 2 years. A measured gravity change of -415 microgal between 1950 and 1961 suggests a permeability of 100 md for rocks in the upper part of the 2-phase zone. This value is consistent with those obtained from well tests.

  16. Dynamics of cell membrane permeability changes at supraphysiological temperatures.

    PubMed Central

    Bischof, J C; Padanilam, J; Holmes, W H; Ezzell, R M; Lee, R C; Tompkins, R G; Yarmush, M L; Toner, M

    1995-01-01

    A quantitative fluorescent microscopy system was developed to characterize, in real time, the effects of supraphysiological temperatures between 37 degrees and 70 degrees C on the plasma membrane of mouse 3T3 fibroblasts and isolated rat skeletal muscle cells. Membrane permeability was assessed by monitoring the leakage as a function of time of the fluorescent membrane integrity probe calcein. The kinetics of dye leakage increased with increasing temperature in both the 3T3 fibroblasts and the skeletal muscle cells. Analytical solutions derived from a two-compartment transport model showed that, for both cell types, a time-dependent permeability assumption provided a statistically better fit of the model predictions to the data than a constant permeability assumption. This finding suggests that the plasma membrane integrity is continuously being compromised while cells are subjected to supraphysiological temperatures. Images FIGURE 1 FIGURE 2 FIGURE 3 PMID:7647264

  17. Permeability and dispersivity of variable-aperture fracture systems

    SciTech Connect

    Tsang, Y.W.; Tsang, C.F.

    1990-01-01

    A number of recent experiments have pointed out the need of including the effects of aperture variation within each fracture in predicting flow and transport properties of fractured media. This paper introduces a new approach in which medium properties, such as the permeability to flow and dispersivity in tracer transport, are correlated to only three statistical parameters describing the fracture aperture probability distribution and the aperture spatial correlation. We demonstrate how saturated permeability and relative permeabilities for flow, as well as dispersion for solute transport in fractures may be calculated. We are in the process of examining the applicability of these concepts to field problems. Results from the evaluation and analysis of the recent Stripa-3D field data are presented. 13 refs., 10 figs.

  18. Reduction of gas and water permeabilities using gels

    SciTech Connect

    Seright, R.S.

    1995-05-01

    The authors investigated how different types of gels reduce permeability to water and gases in porous rock. Five types of gels were studied, including (1) a ``weak`` resorcinol-formaldehyde gel, (2) a ``strong`` resorcinol-formaldehyde gel, (3) a Cr(III)-xanthan gel, (4) a Cr(III)-acetate-HPAM gel, and (5) a colloidal-silica gel. For all gels, extensive coreflood experiments were performed to assess the permeability-reduction characteristics and the stability to repeated water-alternating-gas (WAG) cycles. Studies were performed at pressures up to 1,500 psi using either nitrogen or carbon dioxide as the compressed gas. They developed a coreflood apparatus with an inline high-pressure spectrophotometer that allowed tracer studies to be performed without depressurizing the core. They noted several analogies between the results reported here and those observed during a parallel study of the effects of gel on oil and water permeabilities.

  19. Oxygen permeability of several ceramic oxides above 1200 degrees C

    SciTech Connect

    Courtright, E.L.; Prater, J.T.

    1992-01-01

    Oxygen permeability as a function of temperature was measured for several ceramic oxides over the range 1200 to 1700{degrees}C. Of the oxides testbed, alumina, beryllia, yttria, lanthanum halfnate, and calcium zironcate exhibited the lowest permeabilities in order of decreasing resistance to oxygen transport. None of the permeability constants were less than the 10{sup {minus}10} to 10{sup {minus}12} g O{sub 2}/cm {center dot} s needed for a useful protective coating system above 1500{degrees}C. In some of the mixed oxide compounds, cation segregation was observed to occur with the more rapidly diffusing species segregating to the side of highest oxygen potential. Thus, segregation must be considered when selecting mixed oxides for high temperature applications.

  20. Permeability of rock samples from Cajon Pass, California

    USGS Publications Warehouse

    Morrow, C.; Byerlee, J.

    1988-01-01

    Room temperature, steady-state flow measurements of permeability were conducted on 15 unfractured core samples collected at depths between 270 and 2100 m in the Cajon Pass drillhole. Confining and pore pressures were set to the lithostat and hydrostat for each depth. The first 500 m encountered in the drill hole is composed of sandstones with typically high permeabilities of around 10-17m2. The crystalline rocks between 500 and 2100 m show a systematic decrease in permeability with depth from 10-19 to less than 10-21m2. These values are particularly low relative to the applied effective stresses of only 10-30 MPa, and may be a result of the extensive crack healing that was observed in most samples. -Authors

  1. The mitochondrial permeability transition pore: a mystery solved?

    PubMed Central

    Bernardi, Paolo

    2013-01-01

    The permeability transition (PT) denotes an increase of the mitochondrial inner membrane permeability to solutes with molecular masses up to about 1500 Da. It is presumed to be mediated by opening of a channel, the permeability transition pore (PTP), whose molecular nature remains a mystery. Here I briefly review the history of the PTP, discuss existing models, and present our new results indicating that reconstituted dimers of the FOF1 ATP synthase form a channel with properties identical to those of the mitochondrial megachannel (MMC), the electrophysiological equivalent of the PTP. Open questions remain, but there is now promise that the PTP can be studied by genetic methods to solve the large number of outstanding problems. PMID:23675351

  2. Flow and permeability structure of the Beowawe, Nevada hydrothermal system

    SciTech Connect

    Faulder, D.D.; Johnson, S.D.; Benoit, W.R.

    1997-05-01

    A review of past geologic, geochemical, hydrological, pressure transient, and reservoir engineering studies of Beowawe suggests a different picture of the reservoir than previously presented. The Beowawe hydrothermal contains buoyant thermal fluid dynamically balanced with overlying cold water, as shown by repeated temperature surveys and well test results. Thermal fluid upwells from the west of the currently developed reservoir at the intersection of the Malpais Fault and an older structural feature associated with mid-Miocene rifting. A tongue of thermal fluid rises to the east up the high permeability Malpais Fault, discharges at the Geysers area, and is in intimate contact with overlying cooler water. The permeability structure is closely related to the structural setting, with the permeability of the shallow hydrothermal system ranging from 500 to 1,000 D-ft, while the deeper system ranges from 200 to 400 D-ft.

  3. Direct measurement of the permeability of human cervical tissue.

    PubMed

    Fernandez, Michael; Vink, Joy; Yoshida, Kyoko; Wapner, Ronald; Myers, Kristin M

    2013-02-01

    The mechanical integrity of the uterine cervix is critical for a pregnancy to successfully reach full term. It must be strong to retain the fetus throughout gestation and then undergo a remodeling and softening process before labor for delivery of the fetus. It is believed that cervical insufficiency (CI), a condition in pregnancy resulting in preterm birth (PTB), is related to a cervix with compromised mechanical strength which cannot resist deformation caused by external forces generated by the growing fetus. Such PTBs are responsible for infant developmental problems and in severe cases infant mortality. To understand the etiologies of CI, our overall research goal is to investigate the mechanical behavior of the cervix. Permeability is a mechanical property of hydrated collagenous tissues that dictates the time-dependent response of the tissue to mechanical loading. The goal of this study was to design a novel soft tissue permeability testing device and to present direct hydraulic permeability measurements of excised nonpregnant (NP) and pregnant (PG) human cervical tissue from women with different obstetric histories. Results of hydraulic permeability testing indicate repeatability for specimens from single patients, with an order of magnitude separating the NP and PG group means (2.1 ± 1.4×10(-14) and 3.2 ± 4.8×10(-13)m(4)/N[middle dot]s, respectively), and large variability within the NP and PG sample groups. Differences were found between samples with similar obstetric histories, supporting the view that medical history may not be a good predictor of permeability (and therefore mechanical behavior) and highlighting the need for patient-specific measurements of cervical mechanical properties. The permeability measurements from this study will be used in future work to model the constitutive material behavior of cervical tissue and to develop in vivo diagnostic tools to stage the progression of labor. PMID:23445069

  4. Permeability effects on the seismic response of gas reservoirs

    NASA Astrophysics Data System (ADS)

    Rubino, J. Germán.; Velis, Danilo R.; Holliger, Klaus

    2012-04-01

    In this work, we analyse the role of permeability on the seismic response of sandstone reservoirs characterized by patchy gas-water saturation. We do this in the framework of Johnson's model, which is a generalization of White's seminal model allowing for patches of arbitrary geometry. We first assess the seismic attenuation and velocity dispersion characteristics in response to wave-induced fluid flow. To this end, we perform an exhaustive analysis of the sensitivity of attenuation and velocity dispersion of compressional body waves to permeability and explore the roles played by the Johnson parameters T and S/V, which characterize the shape and size of the gas-water patches. Our results indicate that, within the typical frequency range of exploration seismic data, this sensitivity may indeed be particularly strong for a variety of realistic and relevant scenarios. Next, we extend our analysis to the corresponding effects on surface-based reflection seismic data for two pertinent models of typical sandstone reservoirs. In the case of softer and more porous formations and in the presence of relatively low levels of gas saturation we observe that the effects of permeability on seismic reflection data are indeed significant. These prominent permeability effects prevail for normal-incidence and non-normal-incidence seismic data and for a very wide range of sizes and shapes of the gas-water patches. For harder and less porous reservoirs, the normal-incidence seismic responses exhibit little or no sensitivity to permeability, but the corresponding non-normal-incidence responses show a clear dependence on this parameter, again especially so for low gas saturations. The results of this study therefore suggest that, for a range of fairly common and realistic conditions, surface-based seismic reflection data are indeed remarkably sensitive to the permeability of gas reservoirs and thus have the potential of providing corresponding first-order constraints.

  5. Committee neural network model for rock permeability prediction

    NASA Astrophysics Data System (ADS)

    Bagheripour, Parisa

    2014-05-01

    Quantitative formulation between conventional well log data and rock permeability, undoubtedly the most critical parameter of hydrocarbon reservoir, could be a potent tool for solving problems associated with almost all tasks involved in petroleum engineering. The present study proposes a novel approach in charge of the quest for high-accuracy method of permeability prediction. At the first stage, overlapping of conventional well log data (inputs) was eliminated by means of principal component analysis (PCA). Subsequently, rock permeability was predicted from extracted PCs using multi-layer perceptron (MLP), radial basis function (RBF), and generalized regression neural network (GRNN). Eventually, a committee neural network (CNN) was constructed by virtue of genetic algorithm (GA) to enhance the precision of ultimate permeability prediction. The values of rock permeability, derived from the MPL, RBF, and GRNN models, were used as inputs of CNN. The proposed CNN combines results of different ANNs to reap beneficial advantages of all models and consequently producing more accurate estimations. The GA, embedded in the structure of the CNN assigns a weight factor to each ANN which shows relative involvement of each ANN in overall prediction of rock permeability from PCs of conventional well logs. The proposed methodology was applied in Kangan and Dalan Formations, which are the major carbonate reservoir rocks of South Pars Gas Field-Iran. A group of 350 data points was used to establish the CNN model, and a group of 245 data points was employed to assess the reliability of constructed CNN model. Results showed that the CNN method performed better than individual intelligent systems performing alone.

  6. Upscaling verticle permeability within a fluvio-aeolian reservoir

    SciTech Connect

    Thomas, S.D.; Corbett, P.W.M.; Jensen, J.L.

    1997-08-01

    Vertical permeability (k{sub v}) is a crucial factor in many reservoir engineering issues. To date there has been little work undertaken to understand the wide variation of k{sub v} values measured at different scales in the reservoir. This paper presents the results of a study in which we have modelled the results of a downhole well tester using a statistical model and high resolution permeability data. The work has demonstrates and quantifies a wide variation in k{sub v} at smaller, near wellbore scales and has implications for k{sub v} modelling at larger scales.

  7. Pb2+ Modulates Ca2+ Membrane Permeability In Paramecium

    NASA Astrophysics Data System (ADS)

    Bernal-Martínez, Juan; Ortega Soto, Arturo

    2004-09-01

    Intracellular recording experiments in current clamp configuration were done to evaluate whether Pb2+ modulates ionic membrane permeability in the fresh water Paramecium tetraurelia. It was found that Pb2+ triggers in a dose-dependent manner, a burst of spontaneous action potentials followed by a robust and sustained after hyper-polarization. In addition, Pb2+ increased the frequency of firing the spontaneous Ca2+-Action Potential and also, the duration of Ca2+-Action Potential, in a dose and reversibly-dependent manner. These results suggest that Pb2+ increases calcium membrane permeability of Paramecium and probably activates a calcium-dependent-potassium conductance in the ciliate.

  8. High-permeability pulmonary edema: nursing assessment, diagnosis, and interventions.

    PubMed

    Roberts, S L

    1990-05-01

    High-permeability pulmonary edema (HPPE) is a problem affecting 150,000 to 200,000 critically ill patients yearly. In HPPE the alveolar-capillary membrane is injured. The resulting increased permeability of the alveolar-capillary membrane allows shifts of fluid and protein into the interstitial fluid space and alveolus. As hypoxemia develops, the nurse assesses cardinal signs and symptoms derived from the physical examination and observations. Clinical data consisting of results from various laboratory and diagnostic studies confirm the diagnosis of HPPE. Finally, nursing diagnoses can be delineated as the basis on which expert nursing care is planned and implemented. PMID:2187834

  9. Antidepressants Alter Cerebrovascular Permeability and Metabolic Rate in Primates

    NASA Astrophysics Data System (ADS)

    Preskorn, Sheldon H.; Raichle, Marcus E.; Hartman, Boyd K.

    1982-07-01

    External detection of the annihilation radiation produced by water labeled with oxygen-15 was used to measure cerebrovascular permeability and cerebral blood flow in six rhesus monkeys. Use of oxygen-15 also permitted assessment of cerebral metabolic rate in two of the monkeys. Amitriptyline produced a dose-dependent, reversible increase in permeability at plasma drug concentrations which are therapeutic for depressed patients. At the same concentrations the drug also produced a 20 to 30 percent reduction in cerebral metabolic rate. At higher doses normal autoregulation of cerebral blood flow was suspended, but responsivity to arterial carbon dioxide was normal.

  10. Advanced Glycation End-Product Accumulation Reduces Vitreous Permeability

    PubMed Central

    Lee, On-Tat; Good, Samuel D.; Lamy, Ricardo; Kudisch, Max; Stewart, Jay M.

    2015-01-01

    Purpose. To evaluate the effect of nonenzymatic cross-linking (glycation) upon the permeability of the vitreous to small- and large-solute diffusion. Methods. Vitreous from freshly excised porcine eyes was treated for 30 minutes with control or 0.01%, 0.1%, or 1% methylglyoxal (MG) solution. The efficacy of the glycation regimen was verified by measuring nonenzymatic cross-link density by fluorescence in the vitreous samples. Resistance to collagenase digestion as well as Nε-(carboxyethyl) lysine (CEL) content were also measured. The permeability coefficient for fluorescein and fluorescein isothiocyanate (FITC)-IgG diffusion through 3 mL of the vitreous samples was determined by using a custom permeability tester. Results. Vitreous cross-linking with MG treatment was confirmed by increased fluorescence, increased CEL concentration, and increased resistance to collagenase digestion. Vitreous glycation resulted in a statistically significant decrease in the permeability coefficient for fluorescein diffusion when either 0.1% or 1% MG solution was used (5.36 ± 5.24 × 10−5 cm s−1, P = 0.04; and 4.03 ± 2.1 × 10−5 cm s−1, P = 0.001; respectively, compared with control, 9.77 ± 5.45 × 10−5 cm s−1). The permeability coefficient for diffusion of FITC-IgG between control (9.9 ± 6.37 × 10−5 cm s−1) and treatment groups was statistically significant at all MG concentrations (0.01% MG: 3.95 ± 3.44 × 10−5 cm s−1, P = 0.003; 0.1% MG: 4.27 ± 1.32 × 10−5 cm s−1, P = 0.004; and 0.1% MG: 3.72 ± 2.49 × 10−5 cm s−1, P = 0.001). Conclusions. Advanced glycation end-product (AGE) accumulation reduces vitreous permeability when glycation is performed in ex vivo porcine vitreous. The permeability change was more pronounced for the larger solute, suggesting a lower threshold for AGE-induced permeability changes to impact the movement of proteins through the vitreous when compared with smaller molecules. PMID:26024075

  11. Permeability and structure of resorcinol-formaldehyde gels

    SciTech Connect

    Scherer, G.W.; Alviso, C.; Pekala, R.; Gross, J.

    1996-12-31

    The permeability (D) of resorcinol-formaldehyde (RF) gels was measured using a beam-bending technique. For gels made at various solids contents and with different catalyst contents, the permeabilities ranged over a factor of {approximately} 50; the pore radii inferred from D varied from {approximately}3 to 30 nm. Pore radii obtained on RF aerogels using nitrogen desorption were severely affected by compression of the aerogel by capillary forces (resulting from the surface tension of liquid nitrogen). After correction for that effect, the desorption data were found to be in very good agreement with the pore sizes calculated from D.

  12. Rapidly reversible alterations of pulmonary epithelial permeability induced by smoking

    SciTech Connect

    Mason, G.R.; Uszler, J.M.; Effros, R.M.; Reid, E.

    1983-01-01

    A radioaerosol procedure using /sup 99m/Tc-DTPA (diethylene triamine penta acetate) was used to evaluate the permeability of the pulmonary epithelium in smokers and nonsmokers. The average clearance of this indicator from the lungs of smokers without significant airway obstruction exceeded that found in normal subjects by an average factor of more than five. This abnormality was observed throughout all lung regions. /sup 99m/Tc-DTPA clearance decreased rapidly during the week after smoking was discontinued. It is concluded that smoking results in a rapidly reversible increase in pulmonary epithelial permeability.

  13. Diffusion of DNAPL Components into Low Permeability Soils

    NASA Astrophysics Data System (ADS)

    Ayral, D.; Demond, A. H.

    2013-12-01

    Hazardous waste sites contaminated with dense non-aqueous phase liquids (DNAPLs) have proven difficult to remediate. Even though DNAPLs may be removed from high permeability subsurface strata, the storage of compounds making up DNAPLs in low permeability strata constitutes a secondary source that contributes to a dissolved phase plume over an extended period of time. The movement of DNAPL constituents into and out of low permeable strata is considered to occur through diffusion. However, there are few experimentally measured effective diffusion coefficients for DNAPL components in low permeability soils. Thus, the effective diffusion coefficient is commonly estimated from the aqueous phase diffusion coefficient as a function of the porosity of the soil. This study presents measurements of effective diffusion coefficients of chlorinated solvents and an anionic surfactant dioctyl sodium sulfosuccinate (AOT) in silt and clay-silt mixtures. The experimental results are compared with estimated values to evaluate the performance of commonly used methods to estimate effective diffusion coefficients of DNAPL components. These estimation models generally suggest an increase in the effective diffusion coefficient with an increase in porosity. Yet, in low permeable soils with a substantial fraction of clay, the effective diffusion coefficient for chlorinated solutes decreases, although the porosity increases. Thus, calculations of the quantity of mass stored in low permeable strata may be in error if based on rates of diffusion calculated using such models. In addition to chlorinated solvents, DNAPLs often contain surfactants. The high molecular weight of these solutes results in problems when estimating their effective diffusion coefficient in low permeability soils, since commonly models were formulated for use with low molecular weight compounds. Furthermore, some clay minerals present in low permeable soils have a flexible structure which enables them to expand or

  14. Urban land use: Remote sensing of ground-basin permeability

    NASA Technical Reports Server (NTRS)

    Tinney, L. R.; Jensen, J. R.; Estes, J. E.

    1975-01-01

    A remote sensing analysis of the amount and type of permeable and impermeable surfaces overlying an urban recharge basin is discussed. An effective methodology for accurately generating this data as input to a safe yield study is detailed and compared to more conventional alternative approaches. The amount of area inventoried, approximately 10 sq. miles, should provide a reliable base against which automatic pattern recognition algorithms, currently under investigation for this task, can be evaluated. If successful, such approaches can significantly reduce the time and effort involved in obtaining permeability data, an important aspect of urban hydrology dynamics.

  15. LOW GRADIENT PERMEABILITY MEASUREMENTS IN A TRIAXIAL SYSTEM.

    USGS Publications Warehouse

    Olsen, H.W.; Nichols, R.W.; Rice, T.L.

    1985-01-01

    Permeability measurements were conducted with the flow-pump method on sand, sandy silt and silty clay specimens in a conventional triaxial system by introducing and withdrawing water at known constant flow rates into the base of a specimen with a flow-pump, and by monitoring the head difference induced across the length of the specimen with a sensitive differential pressure transducer. The results show that the previously reported advantages of the flow-pump method, compared with conventional constant head and falling head methods, were realized for permeability measurements in conventional triaxial equipment.

  16. [Investigation of membrane permeability of carp spermatozoa for water molecules].

    PubMed

    Pugovkin, A Iu; Kopeĭka, E F; Nardid, O A; Cherkashina, Ia O

    2014-01-01

    The fundamentals of a photometry method for determination of membrane permeability of some fish spermatozoa for water molecules are presented. Osmotic tolerance of carp spermatozoa membranes was studied using EPR-spectroscopy and photometric analysis methods. It was shown that carp spermatozoa look like the ideal osmometers in their reaction on media of different osmolarity. The value of membrane permeability of carp spermatozoa for water molecules was determined. Data obtained can be used in cryobiology for creating cryoprotective media and regimes of fish sperm cryopreservation. PMID:25715589

  17. Can streaming potential data improve permeability estimates in EGS reservoirs?

    NASA Astrophysics Data System (ADS)

    Vogt, Christian; Klitzsch, Norbert

    2013-04-01

    We study the capability of streaming potential data to improve the estimation of permeability in fractured geothermal systems. To this end, we simulate a tracer experiment numerically carried out at the Enhanced Geothermal System (EGS) at Soultz-sous-Forêts, France, in 2005. The EGS is located in the Lower Rhine Graben. Here, at approximately 5000 m depth an engineered reservoir was established. The tracer circulation test provides information on hydraulic connectivity between the injection borehole GPK3 and the two production boreholes GPK2 and GPK4. Vogt et al. (2011) performed stochastic inversion approaches to estimate heterogeneous permeability at Soultz in an equivalent porous medium approach and studied the non-uniqueness of the possible pathways in the reservoir. They identified three different possible groups of pathway configurations between GPK2 and GPK3 and corresponding hydraulic properties. Using the Ensemble Kalman Fitler, Vogt et al. (2012) estimated permeability by updating sequentially an ensemble of heterogeneous Monte Carlo reservoir models. Additionally, this approach quantifies the heterogeneously distributed uncertainty. Here, we study whether considering hypothetical streaming potential (SP) data during the stochastic inversion can improve the determination of the hydraulic reservoir properties. In particular, we study whether the three groups are characterized uniquely by their corresponding SP signals along the boreholes and whether the Ensemble Kalman Filter fit could be improved by joint inversion of SP and tracer data. During the actual tracer test, no SP data were recorded. Therefore, this study is based on synthetic data. We find that SP data predominantly yields information on the near field of permeability around the wells. Therefore, SP observations along wells will not help to characterize large-scale reservoir flow paths. However, we investigate whether additional passive SP monitoring from deviated wells around the injection

  18. Heterogeneity, permeability patterns, and permeability upscaling: Physical characterization of a block of Massillon sandstone exhibiting nested scales of heterogeneity

    SciTech Connect

    TIDWELL,VINCENT C.; WILSON,JOHN L.

    2000-04-20

    Over 75,000 permeability measurements were collected from a meter-scale block of Massillon sandstone, characterized by conspicuous cross bedding that forms two distinct nested-scales of heterogeneity. With the aid of a gas minipermeameter, spatially exhaustive fields of permeability data were acquired at each of five different sample supports (i.e. sample volumes) from each block face. These data provide a unique opportunity to physically investigate the relationship between the multi-scale cross-stratified attributes of the sandstone and the corresponding statistical characteristics of the permeability. These data also provide quantitative physical information concerning the permeability upscaling of a complex heterogeneous medium. Here, a portion of the data taken from a single block face cut normal to stratification is analyzed. Results indicate a strong relationship between the calculated summary statistics and the cross-stratified structural features visible evident in the sandstone sample. Specifically, the permeability fields and semivariograms are characterized by two nested scales of heterogeneity, including a large-scale structure defined by the cross-stratified sets (delineated by distinct bounding surfaces) and a small-scale structure defined by the low-angle cross-stratification within each set. The permeability data also provide clear evidence of upscaling. That is, each calculated summary statistic exhibits distinct and consistent trends with increasing sample support. Among these trends are an increasing mean, decreasing variance, and an increasing semivariogram range. Results also clearly indicate that the different scales of heterogeneity upscale differently, with the small-scale structure being preferentially filtered from the data while the large-scale structure is preserved. Finally, the statistical and upscaling characteristics of individual cross-stratified sets were found to be very similar owing to their shared depositional environment

  19. Synthetic slings: pros and cons.

    PubMed

    Staskin, David R; Plzak, Louis

    2002-10-01

    Historically, the choice of sling material for the treatment of urinary incontinence has been based on the surgeon's preference and experience. In general, pelvic surgeons have not differentiated artificial graft materials by their inherent qualities or for biocompatibility in the female pelvis and vaginal wall. The introduction of new artificial graft materials and new methods of implantation for the correction of genuine stress incontinence has generated renewed interest in the "pros and cons" associated with nonabsorbable material use. In this review, we discuss and differentiate sling materials and techniques. We consider some of the physical and biologic qualities of artificial graft materials, present theories and practices associated with the successful use of permanent grafts, and discuss the natural evolution of artificial graft slings to the current use of the tension-free vaginal tape and Suprapubic Arc Sling System (American Medical Systems, Minneapolis, MN). PMID:12354353

  20. Predicting chemically-induced skin reactions. Part II: QSAR models of skin permeability and the relationships between skin permeability and skin sensitization

    SciTech Connect

    Alves, Vinicius M.; Muratov, Eugene; Fourches, Denis; Strickland, Judy; Kleinstreuer, Nicole; Tropsha, Alexander

    2015-04-15

    Skin permeability is widely considered to be mechanistically implicated in chemically-induced skin sensitization. Although many chemicals have been identified as skin sensitizers, there have been very few reports analyzing the relationships between molecular structure and skin permeability of sensitizers and non-sensitizers. The goals of this study were to: (i) compile, curate, and integrate the largest publicly available dataset of chemicals studied for their skin permeability; (ii) develop and rigorously validate QSAR models to predict skin permeability; and (iii) explore the complex relationships between skin sensitization and skin permeability. Based on the largest publicly available dataset compiled in this study, we found no overall correlation between skin permeability and skin sensitization. In addition, cross-species correlation coefficient between human and rodent permeability data was found to be as low as R{sup 2} = 0.44. Human skin permeability models based on the random forest method have been developed and validated using OECD-compliant QSAR modeling workflow. Their external accuracy was high (Q{sup 2}{sub ext} = 0.73 for 63% of external compounds inside the applicability domain). The extended analysis using both experimentally-measured and QSAR-imputed data still confirmed the absence of any overall concordance between skin permeability and skin sensitization. This observation suggests that chemical modifications that affect skin permeability should not be presumed a priori to modulate the sensitization potential of chemicals. The models reported herein as well as those developed in the companion paper on skin sensitization suggest that it may be possible to rationally design compounds with the desired high skin permeability but low sensitization potential. - Highlights: • It was compiled the largest publicly-available skin permeability dataset. • Predictive QSAR models were developed for skin permeability. • No concordance between skin

  1. Two Relations to Estimate Membrane Permeability Using Milestoning.

    PubMed

    Votapka, Lane W; Lee, Christopher T; Amaro, Rommie E

    2016-08-25

    Prediction of passive permeation rates of solutes across lipid bilayers is important to drug design, toxicology, and other biological processes such as signaling. The inhomogeneous solubility-diffusion (ISD) equation is traditionally used to relate the position-dependent potential of mean force and diffusivity to the permeability coefficient. The ISD equation is derived via the Smoluchowski equation and assumes overdamped system dynamics. It has been suggested that the complex membrane environment may exhibit more complicated damping conditions. Here we derive a variant of the inhomogeneous solubility diffusion equation as a function of the mean first passage time (MFPT) and show how milestoning, a method that can estimate kinetic quantities of interest, can be used to estimate the MFPT of membrane crossing and, by extension, the permeability coefficient. We further describe a second scheme, agnostic to the damping condition, to estimate the permeability coefficient from milestoning results or other methods that compute a probability of membrane crossing. The derived relationships are tested using a one-dimensional Langevin dynamics toy system confirming that the presented theoretical methods can be used to estimate permeabilities given simulation and milestoning results. PMID:27154639

  2. Demonstrations of Magnetic Phenomena: Measuring the Air Permeability Using Tablets

    ERIC Educational Resources Information Center

    Lara, V. O. M.; Amaral, D. F.; Faria, D.; Vieira, L. P.

    2014-01-01

    We use a tablet to experimentally determine the dependencies of the magnetic field (B) on the electrical current and the axial distance from a coil (z). Our data shows good precision on the inverse cubic dependence of the magnetic field on the axial distance, B?z[superscript -3]. We obtain the value of air permeability µ[subscript air] with good…

  3. Permeable Reactive Barriers for Treatment of Cr6

    EPA Science Inventory

    Several options are available for treatment of hexavalent chromium (Cr(VI)) in groundwater using the permeable reactive barrier (PRB) approach. They include conventional trench-and-fill systems, chemical redox curtains, and organic carbon redox curtains. Each of these PRB syste...

  4. Dissolution-Driven Permeability Reduction of a Fractured Carbonate Caprock

    PubMed Central

    Ellis, Brian R.; Fitts, Jeffrey P.; Bromhal, Grant S.; McIntyre, Dustin L.; Tappero, Ryan; Peters, Catherine A.

    2013-01-01

    Abstract Geochemical reactions may alter the permeability of leakage pathways in caprocks, which serve a critical role in confining CO2 in geologic carbon sequestration. A caprock specimen from a carbonate formation in the Michigan sedimentary Basin was fractured and studied in a high-pressure core flow experiment. Inflowing brine was saturated with CO2 at 40°C and 10 MPa, resulting in an initial pH of 4.6, and had a calcite saturation index of −0.8. Fracture permeability decreased during the experiment, but subsequent analyses did not reveal calcite precipitation. Instead, experimental observations indicate that calcite dissolution along the fracture pathway led to mobilization of less soluble mineral particles that clogged the flow path. Analyses of core sections via electron microscopy, synchrotron-based X-ray diffraction imaging, and the first application of microbeam Ca K-edge X-ray absorption near edge structure, provided evidence that these occlusions were fragments from the host rock rather than secondary precipitates. X-ray computed tomography showed a significant loss of rock mass within preferential flow paths, suggesting that dissolution also removed critical asperities and caused mechanical closure of the fracture. The decrease in fracture permeability despite a net removal of material along the fracture pathway demonstrates a nonintuitive, inverse relationship between dissolution and permeability evolution in a fractured carbonate caprock. PMID:23633894

  5. MICROBIAL CHARACTERIZATION OF MANURE BASED PERMEABLE REACTIVE BARRIER

    EPA Science Inventory

    The implementation of permeable reactive barriers (PRB) provides a viable option for the remediation of contaminants of environmental significance such as dissolved metals (i.e., chromium), chlorinated solvents, and nitrate/ammonia. The designs of PRBs are usually based on the a...

  6. Foamed gel barriers in porous media: Breakdown and permeability evolution

    SciTech Connect

    Miller, M.J.; Fogler, H.S.

    1995-11-01

    Foamed gel has begun to play an important role in permeability modification applications because of the reduced chemical requirements. Foamed gels create impermeable barriers in porous media; however, once a critical pressure differential is exceeded, the permeability increases with increasing pressure. A two-dimensional network model was developed to estimate foamed gel barrier performance in terms of the maximum pressure a barrier can withstand and the evolution of the foamed gel barrier`s permeability. The formation of conductive pathways and the accompanying permeability increase were estimated for a model of the pressure-induced deformation and rupture of individual lenses. The evolution of conductive pathways changed from invasion percolation (high elastic modulus, rigid gel) to a lens rupture chain reaction initiated by the rupture of a single lens (low elastic modulus gel) as the elastic modulus of the gel was decreased. The apparent fractal dimension of the first conductive channel ranged from 1.89 to 1.06 for high and low elastic modulus gels., respectively. This dependency of breakthrough and breakdown is unique and produces a large range of breakdown behavior for any degree of microscopic heterogeneity.

  7. Nutrient Infiltrate Concentrations from Three Permeable Pavement Types

    EPA Science Inventory

    While permeable pavement is increasingly being used to control stormwater runoff, field-based, side-by-side investigations on the effects different pavement types have on nutrient concentrations present in stormwater runoff are limited. In 2009, the U.S. EPA constructed a 0.4-ha...

  8. Structural permeability of fluid-driven fault-fracture meshes

    NASA Astrophysics Data System (ADS)

    Sibson, Richard H.

    1996-08-01

    Fluid redistribution in the crust is influenced by hydraulic gradient, by existing permeability anisotropy arising from bedding and other forms of layering, and by structural permeability developed under the prevailing stress field. Field evidence suggests that mesh structures, comprising faults interlinked with extensional-shear and purely extensional vein-fractures, form important conduits for large volume flow of hydrothermal and hydrocarbon fluids. Meshes may be 'self-generated' by the infiltration of pressurised fluids into a stressed heterogeneous rock mass with varying material properties, developing best where bulk coaxial strain is symmetric with existing layering, but they also form under predominantly simple shear. Fluid passage through such structures generates earthquake swarm activity by distributed fault-valve action along suprahydrostatic gradients that may arise from compaction overpressuring, metamorphic dewatering, magmatic intrusion, and mantle degassing. Within mesh structures, strong directional permeability may develop in the σ2 direction parallel to fault-fracture intersections and orthogonal to fault slip vectors. In particular tectonic settings, this promotes strongly focused flow with high potential for mineralisation. Mesh activation requires the condition Pf ~ σ3 to be maintained for the structures to remain high permeability conduits, requiring fluid overpressuring at other than shallow depths in extensional-transtensional regimes. Favoured localities for mesh development include linkage structures along large-displacement fault zones such as dilational jogs, lateral ramps, and transfer faults. In some circumstances, mesh formation appears to precede the development of major faults.

  9. The Permeability Transition in Plant Mitochondria: The Missing Link

    PubMed Central

    Zancani, Marco; Casolo, Valentino; Petrussa, Elisa; Peresson, Carlo; Patui, Sonia; Bertolini, Alberto; De Col, Valentina; Braidot, Enrico; Boscutti, Francesco; Vianello, Angelo

    2015-01-01

    The synthesis of ATP in mitochondria is dependent on a low permeability of the inner membrane. Nevertheless, mitochondria can undergo an increased permeability to solutes, named permeability transition (PT) that is mediated by a permeability transition pore (PTP). PTP opening requires matrix Ca2+ and leads to mitochondrial swelling and release of intramembrane space proteins (e.g., cytochrome c). This feature has been initially observed in mammalian mitochondria and tentatively attributed to some components present either in the outer or inner membrane. Recent works on mammalian mitochondria point to mitochondrial ATP synthase dimers as physical basis for PT, a finding that has been substantiated in yeast and Drosophila mitochondria. In plant mitochondria, swelling and release of proteins have been linked to programmed cell death, but in isolated mitochondria PT has been observed in only a few cases and in plant cell cultures only indirect evidence is available. The possibility that mitochondrial ATP synthase dimers could function as PTP also in plants is discussed here on the basis of the current evidence. Finally, a hypothetical explanation for the origin of PTP is provided in the framework of molecular exaptation. PMID:26697057

  10. MEASUREMENT OF THE SURFACE PERMEABILITY OF BASEMENT CONCRETES

    EPA Science Inventory

    The report discusses the development, testing, and use of a portable surface permeameter suitable for field use in measuring the surface permeability of concrete in new houses. he permeameter measures the airflow induced by a pressure difference across a temporary test seal appli...

  11. PERMEABILITY PROPERTIES OF FLY ASH FORM FURNACE SORBENT INJECTION PROCESS

    EPA Science Inventory

    The paper discusses tests of the applicability of furnace sorbent injection (FSI) waste solids for use as synthetic waste landfill liners by measuring the mechanical strength and permeability of moisture-cured samples. SI waste solids were received from the EPA-sponsored demonstr...

  12. Monitoring Strategies in Permeable Pavement Systems to Optimize Maintenance Scheduling

    EPA Science Inventory

    As the surface in a permeable pavement system clogs and performance decreases, maintenance is required to preserve the design function. Currently, guidance is limited for scheduling maintenance on an as needed basis. Previous research has shown that surface clogging in a permea...

  13. Advanced Organic Permeable-Base Transistor with Superior Performance.

    PubMed

    Klinger, Markus P; Fischer, Axel; Kaschura, Felix; Scholz, Reinhard; Lüssem, Björn; Kheradmand-Boroujeni, Bahman; Ellinger, Frank; Kasemann, Daniel; Leo, Karl

    2015-12-16

    An optimized vertical organic permeable-base transistor (OPBT) competing with the best organic field-effect transistors in performance, while employing low-cost fabrication techniques, is presented. The OPBT stands out by its excellent power efficiency at the highest frequencies. PMID:26484500

  14. PERMEABLE REACTIVE BARRIERS FOR REMEDIATION OF INORGANIC CONTAMINANTS

    EPA Science Inventory

    The permeable reactive barrier (PRB) technology is an in-situ approach for groundwater remediation that couples subsurface flow management with a passive chemical or biochemical treatment zone. The development and application of the PRB technology has progressed over the last de...

  15. PERMEABLE TREATMENT WALL EFFECTIVENESS MONITORING PROJECT, NEVADA STEWART MINE

    EPA Science Inventory

    This report summarizes the results of Mine Waste Technology Program (MWTP) Activity III, Project 39, Permeable Treatment Wall Effectiveness Monitoring Project, implemented and funded by the U.S. Environmental Protection Agency (EPA) and jointly administered by EPA and the U.S. De...

  16. MEAUSREMENT OF THE SURFACE PERMEABILITY OF BASEMENT CONCRETES

    EPA Science Inventory

    The report discusses the development, testing, and use of a portable surface permeameter suitable for field use in measuring the surface permeability of concrete in new houses. he permeameter measures the airflow induced by a pressure difference across a temporary test seal appli...

  17. Permeability changes in coal resulting from gas desorption

    SciTech Connect

    Levine, J.R.; Johnson, P.M.

    1992-01-01

    Research continued on the study of coal permeability and gas desorption. This quarter, most of the effort involved identifying problems with the microbalance and then getting it repaired. Measurement of the amount of gas adsorbed with the microbalance involved corrections for the buoyancy change with pressure and several experiments with helium were made to determine this correction.

  18. Effects of discontinuous magnetic permeability on magnetodynamic problems

    NASA Astrophysics Data System (ADS)

    Guermond, J.-L.; Léorat, J.; Luddens, F.; Nore, C.; Ribeiro, A.

    2011-07-01

    A novel approximation technique using Lagrange finite elements is proposed to solve magneto-dynamics problems involving discontinuous magnetic permeability and non-smooth interfaces. The algorithm is validated on benchmark problems and is used for kinematic studies of the Cadarache von Kármán Sodium 2 (VKS2) experimental fluid dynamo.

  19. Ammonia recovery from livestock waste using gas permeable membrane technology

    Technology Transfer Automated Retrieval System (TEKTRAN)

    This presentation shows new methods and systems being developed for reducing ammonia emissions from livestock waste and recovering concentrated liquid nitrogen that could be sold as fertilizer. These systems use gas-permeable membranes as components of new processes to capture and recover the ammoni...

  20. Ammonia recovery from livestock wastewater with gas permeable membranes

    Technology Transfer Automated Retrieval System (TEKTRAN)

    This presentation shows new methods and systems being developed for reducing ammonia emissions from livestock waste and recovering concentrated liquid nitrogen that could be sold as fertilizer. These systems use gas-permeable membranes as components of new processes to capture and recover the ammoni...

  1. Increased endothelial cell permeability in endoglin-deficient cells.

    PubMed

    Jerkic, Mirjana; Letarte, Michelle

    2015-09-01

    Endoglin (ENG) is a TGF-β superfamily coreceptor essential for vascular endothelium integrity. ENG mutations lead to a vascular dysplasia associated with frequent hemorrhages in multiple organs, whereas ENG null mouse embryos die at midgestation with impaired heart development and leaky vasculature. ENG interacts with several proteins involved in cell adhesion, and we postulated that it regulates vascular permeability. The current study assessed the permeability of ENG homozygous null (Eng(-/-)), heterozygous (Eng(+/-)), and normal (Eng(+/+)) mouse embryonic endothelial cell (EC) lines. Permeability, measured by passage of fluorescent dextran through EC monolayers, was increased 2.9- and 1.7-fold for Eng(-/-) and Eng(+/-) ECs, respectively, compared to control ECs and was not increased by TGF-β1 or VEGF. Prolonged starvation increased Eng(-/-) EC permeability by 3.7-fold with no effect on control ECs; neutrophils transmigrated faster through Eng(-/-) than Eng(+/+) monolayers. Using a pull-down assay, we demonstrate that Ras homolog gene family (Rho) A is constitutively active in Eng(-/-) and Eng(+/-) ECs. We show that the endothelial barrier destabilizing factor thrombospondin-1 and its receptor-like protein tyrosine phosphatase are increased, whereas stabilizing factors VEGF receptor 2, vascular endothelial-cadherin, p21-activated kinase, and Ras-related C3 botulinum toxin substrate 2 are decreased in Eng(-/-) cells. Our findings indicate that ENG deficiency leads to EC hyperpermeability through constitutive activation of RhoA and destabilization of endothelial barrier function. PMID:25972355

  2. An asymptotic model of seismic reflection from a permeable layer

    SciTech Connect

    Silin, D.; Goloshubin, G.

    2009-10-15

    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 of 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.

  3. Salmonella Rapidly Regulates Membrane Permeability To Survive Oxidative Stress

    PubMed Central

    van der Heijden, Joris; Reynolds, Lisa A.; Deng, Wanyin; Mills, Allan; Scholz, Roland; Imami, Koshi; Foster, Leonard J.; Duong, Franck

    2016-01-01

    ABSTRACT The outer membrane (OM) of Gram-negative bacteria provides protection against toxic molecules, including reactive oxygen species (ROS). Decreased OM permeability can promote bacterial survival under harsh circumstances and protects against antibiotics. To better understand the regulation of OM permeability, we studied the real-time influx of hydrogen peroxide in Salmonella bacteria and discovered two novel mechanisms by which they rapidly control OM permeability. We found that pores in two major OM proteins, OmpA and OmpC, could be rapidly opened or closed when oxidative stress is encountered and that the underlying mechanisms rely on the formation of disulfide bonds in the periplasmic domain of OmpA and TrxA, respectively. Additionally, we found that a Salmonella mutant showing increased OM permeability was killed more effectively by treatment with antibiotics. Together, these results demonstrate that Gram-negative bacteria regulate the influx of ROS for defense against oxidative stress and reveal novel targets that can be therapeutically targeted to increase bacterial killing by conventional antibiotics. PMID:27507830

  4. PERMEABLE REACTIVE WALL REMEDIATION OF CHLORINATED HYDROCARBONS IN GROUNDWATER

    EPA Science Inventory

    A pilot-scale permeable reactive barrier was installed at Moffett Field in April 1996 and its performance was monitored over the following 16 months on a quarterly basis. The details of this study are described in a technology evaluation report (Battelle, 1998). This document pro...

  5. Quantifying tight-gas sandstone permeability via critical path analysis

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Rock permeability has been actively investigated over the past several decades by the geosciences community. However, its accurate estimation still presents significant technical challenges, especially in spatially complex rocks. In this letter, we apply critical path analysis (CPA) to estimate perm...

  6. Chloroquine and Hydroxychloroquine Increase Retinal Pigment Epithelial Layer Permeability.

    PubMed

    Korthagen, Nicoline M; Bastiaans, Jeroen; van Meurs, Jan C; van Bilsen, Kiki; van Hagen, P Martin; Dik, Willem A

    2015-07-01

    Antimalarials chloroquine (CQ) and hydroxychloroquine (HCQ) are widely used as antiinflammatory drugs, but side effects include retinopathy and vision loss. The objective of this study was to examine the effect of CQ and HCQ on the barrier integrity of retinal pigment epithelial (RPE) cell monolayers in vitro. Permeability of ARPE-19 cell monolayers was determined using Fluorescein isothiocyanate (FITC)-labeled dextran. The influence of CQ and HCQ on cell death and the expression tight junction molecules was examined. CQ and HCQ significantly increased ARPE-19 monolayer permeability after 3 and 18 h, respectively, and enhanced mRNA levels for claudin-1 and occludin. Cytotoxicity was only observed after 18 h exposure. Thus, CQ and HCQ rapidly enhance RPE barrier permeability in vitro, independent of cytotoxicity or loss of zonula occludens-1, claudin-1, and occludin expression. Our findings suggest that CQ/HCQ-induced permeability of the RPE layer may contribute to blood-retinal barrier breakdown in case of CQ/HCQ-induced retinopathy. PMID:25752684

  7. Permeability of rhynchophylline across human intestinal cell in vitro.

    PubMed

    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

  8. Dissolution-Driven Permeability Reduction of a Fractured Carbonate Caprock

    SciTech Connect

    Ellis, Brian R; Fitts, Jeffrey P; Bromhal, Grant S; McIntyre, Dustin L; Tappero, Ryan; Peters, Catherine

    2013-04-01

    Geochemical reactions may alter the permeability of leakage pathways in caprocks, which serve a critical role in confining CO{sub 2} in geologic carbon sequestration. A caprock specimen from a carbonate formation in the Michigan sedimentary Basin was fractured and studied in a high-pressure core flow experiment. Inflowing brine was saturated with CO{sub 2} at 40°C and 10 MPa, resulting in an initial pH of 4.6, and had a calcite saturation index of −0.8. Fracture permeability decreased during the experiment, but subsequent analyses did not reveal calcite precipitation. Instead, experimental observations indicate that calcite dissolution along the fracture pathway led to mobilization of less soluble mineral particles that clogged the flow path. Analyses of core sections via electron microscopy, synchrotron-based X-ray diffraction imaging, and the first application of microbeam Ca K-edge X-ray absorption near edge structure, provided evidence that these occlusions were fragments from the host rock rather than secondary precipitates. X-ray computed tomography showed a significant loss of rock mass within preferential flow paths, suggesting that dissolution also removed critical asperities and caused mechanical closure of the fracture. The decrease in fracture permeability despite a net removal of material along the fracture pathway demonstrates a nonintuitive, inverse relationship between dissolution and permeability evolution in a fractured carbonate caprock.

  9. The permeability of rabbit and human corneal endothelium.

    PubMed Central

    Hodson, S; Wigham, C

    1983-01-01

    The fluxes of sodium, chloride and bicarbonate across endothelium plus stroma and then stroma alone were measured in the direction from lens-side to tear-side in rabbit and human corneas in vitro, in order to measure passive permeabilities. The results were used to calculate the permeability of the endothelium. Hodgkin's equation (1951) was then used to calculate the partial electrical conductivity of each ion crossing the endothelium. The summated electrical conductivities of sodium, chloride and bicarbonate were equal to 89 +/- 8% of the measured electrical conductivity, suggesting that the ions diffuse independently across the endothelium in the direction lens-side to tear-side. Stereological analysis of the intercellular spaces supports the idea that the ions permeate through this route and that the physical shape of the spaces determines almost entirely the permeability of the endothelial layer. Trans-endothelial sodium and chloride permeabilities are nearly equal, which may be explained by supposing the intercellular spaces include a cation exchanger of fixed negative charge capacity around 60 m-equiv l.-1 intercellular fluid. PMID:6631742

  10. Aeroperformance and Acoustics of the Nozzle with Permeable Shell

    NASA Technical Reports Server (NTRS)

    Gilinsky, M.; Blankson, I. M.; Chernyshev, S. A.; Chernyshev, S. A.

    1999-01-01

    Several simple experimental acoustic tests of a spraying system were conducted at the NASA Langley Research Center. These tests have shown appreciable jet noise reduction when an additional cylindrical permeable shell was employed at the nozzle exit. Based on these results, additional acoustic tests were conducted in the anechoic chamber AK-2 at the Central Aerohydrodynamics Institute (TsAGI, Moscow) in Russia. These tests examined the influence of permeable shells on the noise from a supersonic jet exhausting from a round nozzle designed for exit Mach number, M (sub e)=2.0, with conical and Screwdriver-shaped centerbodies. The results show significant acoustic benefits of permeable shell application especially for overexpanded jets by comparison with impermeable shell application. The noise reduction in the overall pressure level was obtained up to approximately 5-8%. Numerical simulations of a jet flow exhausting from a convergent-divergent nozzle designed for exit Mach number, M (sub e)=2.0, with permeable and impermeable shells were conducted at the NASA LaRC and Hampton University. Two numerical codes were used. The first is the NASA LaRC CFL3D code for accurate calculation of jet mean flow parameters on the basis of a full Navier-Stokes solver (NSE). The second is the numerical code based on Tam's method for turbulent mixing noise (TMN) calculation. Numerical and experimental results are in good qualitative agreement.

  11. 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

  12. Iron abundance and magnetic permeability of the moon

    NASA Technical Reports Server (NTRS)

    Parkin, C. W.; Daily, W. D.; Dyal, P.

    1974-01-01

    A set of simultaneous data from the Apollo 12 lunar surface magnetometer and the Explorer 35 Ames magnetometer are used to construct a whole-moon hysteresis curve, from which a new value of global lunar permeability is determined to be mu = 1.012 + or - 0.006. The corresponding global induced dipole moment is 2.1 x 10 to the 18th power gauss-cucm for typical inducing fields of .1000 gauss in the lunar environment. From the permeability measurement, lunar free iron abundance is determined to be 2.5 + or - 2.0 wt. %. Total iron abundance is calculated for two assumed compositional models of the lunar interior: a free iron/orthopyroxene lunar composition and a free iron/olivine composition. The overall lunar total iron abundance is determined to be 9.0 + or - 4.7 wt. %. Other lunar models with a small iron core and with a shallow iron-rich layer are discussed in light of the measured global permeability. Effects on permeability and iron content calculations due to a possible lunar ionosphere are also considered.

  13. Evaluation of unsaturated zone air permeability through pneumatic tests

    USGS Publications Warehouse

    Baehr, Arthur L.; Hult, Marc F.

    1991-01-01

    Predicting the steady state distribution of air pressure in the unsaturated zone resulting from a pneumatic test provides a method for determining air-phase permeability. This technique is analogous to the inverse problem of well hydraulics; however, air flow is more complicated than ground water flow because of air compressibility, the Klinkenberg effect, variations in air density and viscosity that result from temperature fluctuations in the unsaturated zone and the possibility of inducing water movement during the pneumatic test. An analysis of these complicating factors reveals that, when induced water movement can be neglected, a linear version of the airflow equation can provide an appropriate approximation for the purpose of determining air-phase permeability. Two analytical solutions for steady state, two-dimensional, axisymmetric airflow to a single well partially screened in the unsaturated zone are developed. One solution applies where there is a stratum of relatively low air permeability, separating the stratum in which the well is completed, from the atmosphere. The other solution applies where there is no separating stratum between the domain and atmosphere. In both situations the water table forms the lower horizontal boundary. Applications of both solutions to determine air permeability from data collected during pneumatic tests are presented.

  14. Iron abundance and magnetic permeability of the moon

    NASA Technical Reports Server (NTRS)

    Parkin, C. W.; Daily, W. D.; Dyal, P.

    1974-01-01

    A larger set of simultaneous data from the Apollo 12 lunar surface magnetometer and the Explorer 35 Ames magnetometer are used to construct a whole-moon hysteresis curve, from which a new value of global lunar permeability is determined to be mu = 1.012 + or - 0.006. The corresponding global induced dipole moment is 2.1 times ten to the eighteenth power gauss-cu cm for typical inducing fields of one ten-thousandth gauss in the lunar environment. From the permeability measurement, lunar free iron abundance is determined to be 2.5 + or - 2.0 wt %. Total iron abundance (sum of iron in the ferromagnetic and paramagnetic states) is calculated for two assumed compositional models of the lunar interior: a free iron/orthopyroxene lunar composition and a free iron/olivine composition. The overall lunar total iron abundance is determined to be 9.0 + or - 4.7 wt %. Other lunar models with a small iron core and with a shallow iron-rich layer are discussed in light of the measured global permeability. Effects on permeability and iron content calculations due to a possible lunar ionosphere are also considered.

  15. 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.

  16. Investigation of the feasibility of developing low permeability polymeric films

    NASA Technical Reports Server (NTRS)

    Hoggatt, J. T.

    1971-01-01

    The feasibility of reducing the gas permeability rate of Mylar and Kapton films without drastically effecting their flexibility characteristics at cryogenic temperatures was considered. This feasibility was established using a concept of diffusion bonding two layers of metallized films together forming a film-metal-film sandwich laminate. The permeability of kapton film to gaseous helium was reduced from a nominal ten = to the minus 9 power cc-mm/sq cm sec. cm Hg to ten to the minus 13 power cc-mm/ sq cm - sec. cm Hg with some values as low as ten to the minus 15 power cc - mm/sq cm m-sec - cm Hg being obtained. Similar reductions occurred in the liquid hydrogen permeability at -252 C. In the course of the program the permeability, flexibility and bond strength of plain, metalized and diffusion bond film were determined at +25 C, -195 C and -252 C. The cryogenic flexibility of Kapton film was reduced slightly due to the metallization process but no additional loss in flexibility resulted from the diffusion bonding process.

  17. Redox-controlled molecular permeability of composite-wall microcapsules

    NASA Astrophysics Data System (ADS)

    Ma, Yujie; Dong, Wen-Fei; Hempenius, Mark A.; Möhwald, Helmuth; Julius Vancso, G.

    2006-09-01

    Many smart materials in bioengineering, nanotechnology and medicine allow the storage and release of encapsulated drugs on demand at a specific location by an external stimulus. Owing to their versatility in material selection, polyelectrolyte multilayers are very promising systems in the development of microencapsulation technologies with permeation control governed by variations in the environmental conditions. Here, organometallic polyelectrolyte multilayer capsules, composed of polyanions and polycations of poly(ferrocenylsilane) (PFS), are introduced. Their preparation involved layer-by-layer self-assembly onto colloidal templates followed by core removal. PFS polyelectrolytes feature redox-active ferrocene units in the main chain. Incorporation of PFS into the capsule walls allowed us to explore the effects of a new stimulus, that is, changing the redox state, on capsule wall permeability. The permeability of these capsules could be sensitively tuned via chemical oxidation, resulting in a fast capsule expansion accompanied by a drastic permeability increase in response to a very small trigger. The substantial swelling could be suppressed by the application of an additional coating bearing common redox-inert species of poly(styrene sulfonate) (PSS-) and poly(allylamine hydrochloride) (PAH+) on the outer wall of the capsules. Hence, we obtained a unique capsule system with redox-controlled permeability and swellability with a high application potential in materials as well as in bioscience.

  18. Measuring Clogging with Pressure Transducers in Permeable Pavement Strips

    EPA Science Inventory

    Two issues that have a negative affect on the long term hydrologic performance of permeable pavement systems are surface clogging and clogging at the interface with the underlying soil. Surface clogging limits infiltration capacity and results in bypass if runoff rate exceeds in...

  19. Two Relations to Estimate Membrane Permeability Using Milestoning

    PubMed Central

    2016-01-01

    Prediction of passive permeation rates of solutes across lipid bilayers is important to drug design, toxicology, and other biological processes such as signaling. The inhomogeneous solubility-diffusion (ISD) equation is traditionally used to relate the position-dependent potential of mean force and diffusivity to the permeability coefficient. The ISD equation is derived via the Smoluchowski equation and assumes overdamped system dynamics. It has been suggested that the complex membrane environment may exhibit more complicated damping conditions. Here we derive a variant of the inhomogeneous solubility diffusion equation as a function of the mean first passage time (MFPT) and show how milestoning, a method that can estimate kinetic quantities of interest, can be used to estimate the MFPT of membrane crossing and, by extension, the permeability coefficient. We further describe a second scheme, agnostic to the damping condition, to estimate the permeability coefficient from milestoning results or other methods that compute a probability of membrane crossing. The derived relationships are tested using a one-dimensional Langevin dynamics toy system confirming that the presented theoretical methods can be used to estimate permeabilities given simulation and milestoning results. PMID:27154639

  20. LONG-TERM PERFORMANCE OF PERMEABLE REACTIVE BARRIERS: LESSONS LEARNED

    EPA Science Inventory

    This presentation will provide an overview of research efforts at EPA on the application, monitoring, and performance of Permeable Reactive Barriers (PRBs) for groundwater restoration. Over the past 10 years, research projects conducted by research staff at EPA's National Risk M...

  1. COLLECTION OF DESIGN DATA: SITE CHARACTERIZATION FOR PERMEABLE REACTIVE BARRIERS

    EPA Science Inventory

    Permeable reactive barriers (PRBs) for the restoration of contaminated ground water are no longer innovative. PRBs have evolved from innovative to accepted, standard practice, for the containment and treatment of a variety of contaminants in ground water. Like any remedial tech...

  2. Permeability Evolution and the Mechanisms of Porosity Change (Invited)

    NASA Astrophysics Data System (ADS)

    Zhu, W.; Gribbin, J. L.; Tivey, M. K.

    2013-12-01

    Understanding subsurface fluid flow is of critical importance to such geological and engineering applications as faulting mechanics, hydrothermal venting and resource recovery. Mechanical, chemical and thermal loads can significantly alter microscopic pore geometry and thus affect macroscopic permeability. Recently, we measured the permeability and porosity of massive anhydrite deposits recovered from various seafloor hydrothermal vent fields. Together, these deposits comprise anhydrite samples that have undergone different stages of formation. For anhydrite samples with porosities greater than 5%, the dependence of permeability to porosity change is best characterized by a power-law relationship with an exponent n~9. At porosities less than 5%, a much gentler trend of n~1 is observed. These permeability-porosity relationships (PPRs) in anhydrite deposits are in stark contrast to those of Fontainebleau sandstone, a quartz arenite with various degrees of quartz cementation. Fontainebleau sandstone shows a power-law dependence of PPR with an exponent of n~3 for samples with porosities greater than 7%, and a much steeper trend of n~8 at low porosities [Bourbie and Zinszner, 1985]. Microstructural analysis and numerical models suggest that the significant loss in pore connectivity below 7% is responsible for the steeper PPR trend in Fontainebleau sandstone [Zhu et al., 1995]. In anhydrite deposits, petrographic analyses show evidence for both dissolution and precipitation, consistent with the observed PPRs resulting from pore-size controlled solubility. Precipitation of anhydrite takes place preferentially in large pores within the anhydrite deposits, with precipitation limited in small pores, which is proposed to be due to the change in interfacial energy of the growing crystal (e.g., as described by Emmanuel and Ague [2009]). With abundant large voids in high porosity anhydrite samples, the growth of sulfates would result in a drastic loss of pore connectivity and

  3. A study of the osmotic characteristics, water permeability, and cryoprotectant permeability of human vaginal immune cells

    PubMed Central

    Shu, Zhiquan; Hughes, Sean M.; Fang, Cifeng; Huang, Jinghua; Fu, Baiwen; Zhao, Gang; Fialkow, Michael; Lentz, Gretchen; Hladik, Florian; Gao, Dayong

    2016-01-01

    Cryopreservation of specimens taken from the genital tract of women is important for studying mucosal immunity during HIV prevention trials. However, it is unclear whether the current, empirically developed cryopreservation procedures for peripheral blood cells are also ideal for genital specimens. The optimal cryopreservation protocol depends on the cryobiological features of the cells. Thus, we obtained tissue specimens from vaginal repair surgeries, isolated and flow cytometry-purified immune cells, and determined fundamental cryobiological characteristics of vaginal CD3+ T cells and CD14+ macrophages using a microfluidic device. The osmotically inactive volumes of the two cell types (Vb) were determined relative to the initial cell volume (V0) by exposing the cells to hypotonic and hypertonic saline solutions, evaluating the equilibrium volume, and applying the Boyle van't Hoff relationship. The cell membrane permeability to water (Lp) and to four different cryoprotective agent (CPA) solutions (Ps) at room temperature were also measured. Results indicated Vb values of 0.516 V0 and 0.457 V0 for mucosal T cells and macrophages, respectively. Lp values at room temperature were 0.196 and 0.295 μm/min/atm for T cells and macrophages, respectively. Both cell types had high Ps values for the three CPAs, dimethyl sulfoxide (DMSO), propylene glycol (PG) and ethylene glycol (EG) (minimum of 0.418 × 10−3 cm/min), but transport of the fourth CPA, glycerol, occurred 50–150 times more slowly. Thus, DMSO, PG, and EG are better options than glycerol in avoiding severe cell volume excursion and osmotic injury during CPA addition and removal for cryopreservation of human vaginal immune cells. PMID:26976225

  4. A study of the osmotic characteristics, water permeability, and cryoprotectant permeability of human vaginal immune cells.

    PubMed

    Shu, Zhiquan; Hughes, Sean M; Fang, Cifeng; Huang, Jinghua; Fu, Baiwen; Zhao, Gang; Fialkow, Michael; Lentz, Gretchen; Hladik, Florian; Gao, Dayong

    2016-04-01

    Cryopreservation of specimens taken from the genital tract of women is important for studying mucosal immunity during HIV prevention trials. However, it is unclear whether the current, empirically developed cryopreservation procedures for peripheral blood cells are also ideal for genital specimens. The optimal cryopreservation protocol depends on the cryobiological features of the cells. Thus, we obtained tissue specimens from vaginal repair surgeries, isolated and flow cytometry-purified immune cells, and determined fundamental cryobiological characteristics of vaginal CD3(+) T cells and CD14(+) macrophages using a microfluidic device. The osmotically inactive volumes of the two cell types (Vb) were determined relative to the initial cell volume (V0) by exposing the cells to hypotonic and hypertonic saline solutions, evaluating the equilibrium volume, and applying the Boyle van't Hoff relationship. The cell membrane permeability to water (Lp) and to four different cryoprotective agent (CPA) solutions (Ps) at room temperature were also measured. Results indicated Vb values of 0.516 V0 and 0.457 V0 for mucosal T cells and macrophages, respectively. Lp values at room temperature were 0.196 and 0.295 μm/min/atm for T cells and macrophages, respectively. Both cell types had high Ps values for the three CPAs, dimethyl sulfoxide (DMSO), propylene glycol (PG) and ethylene glycol (EG) (minimum of 0.418 × 10(-3) cm/min), but transport of the fourth CPA, glycerol, occurred 50-150 times more slowly. Thus, DMSO, PG, and EG are better options than glycerol in avoiding severe cell volume excursion and osmotic injury during CPA addition and removal for cryopreservation of human vaginal immune cells. PMID:26976225

  5. Tritium Permeability of Incoloy 800H and Inconel 617

    SciTech Connect

    Philip Winston; Pattrick Calderoni; Paul Humrickhouse

    2011-09-01

    Design of the Next Generation Nuclear Plant (NGNP) reactor and its high-temperature components requires information regarding the permeation of fission generated tritium and hydrogen product through candidate heat exchanger alloys. Release of fission-generated tritium to the environment and the potential contamination of the helium coolant by permeation of product hydrogen into the coolant system represent safety basis and product contamination issues. Of the three potential candidates for high-temperature components of the NGNP reactor design, only permeability for Incoloy 800H has been well documented. Hydrogen permeability data have been published for Inconel 617, but only in two literature reports and for partial pressures of hydrogen greater than one atmosphere, far higher than anticipated in the NGNP reactor. To support engineering design of the NGNP reactor components, the tritium permeability of Inconel 617 and Incoloy 800H was determined using a measurement system designed and fabricated at Idaho National Laboratory. The tritium permeability of Incoloy 800H and Inconel 617, was measured in the temperature range 650 to 950 C and at primary concentrations of 1.5 to 6 parts per million volume tritium in helium. (partial pressures of 10-6 atm) - three orders of magnitude lower partial pressures than used in the hydrogen permeation testing. The measured tritium permeability of Incoloy 800H and Inconel 617 deviated substantially from the values measured for hydrogen. This may be due to instrument offset, system absorption, presence of competing quantities of hydrogen, surface oxides, or other phenomena. Due to the challenge of determining the chemical composition of a mixture with such a low hydrogen isotope concentration, no categorical explanation of this offset has been developed.

  6. Measuring the vertical permeability of horizontally- stratified sedimentary rocks

    SciTech Connect

    Novakowski, K.S.; Lapcevic, P.A. ); Reichart, T.M. )

    1993-03-01

    The vertical permeability of horizontally stratified rocks is usually assumed to be significantly less than the permeability of horizontal structural features such as bedding plane partings and sheeting structure. Consequently it is also assumed that this type of media provides suitable vertical barriers to the migration of both aqueous and non-aqueous phase groundwater contaminants. To investigate this assumption, a site adjacent to an inactive dolostone quarry was instrumented using nine boreholes drilled to a depth of approximately 25 m in a 30 x 30 m area. The area is immediately underlain by flat-lying thick-bedded dolostones of Middle-Silurian age. Six of the boreholes were drilled at angle of 45[degree] to intersect two vertical fracture sets oriented at 020[degree] and 110[degree] which were identified by mapping the fractures in the quarry. Detailed hydraulic tests (constant-head method) were conducted in each of the boreholes using a packer spacing of 0.5 m to determine the hydraulic properties of the individual horizontal and vertical fractures and fracture zones. In addition, four pumping tests were conducted in which a fracture zone in one of the vertical boreholes was shut-in and pumped and the hydraulic response was monitored in the observation boreholes using pressure transducer installed in 15 intervals isolated with multiple-packer strings. The results of the constant-head tests show that although the groundwater flow system in the dolostone is dominated by 3--4 horizontal fracture zones, the average permeability of the vertical fractures is only one order of magnitude less than the average permeability of the horizontal fractures. However, this aspect of the flow system is not detected using pumping tests, the results of which suggest that the average permeability is 3--4 orders of magnitude less in the vertical direction.

  7. Role of different biodegradable polymers on the permeability of ciprofloxacin

    PubMed Central

    Chakraborti, Chandra Kanti; Sahoo, Subhashree; Behera, Pradipta Kumar

    2014-01-01

    Since permeability across biological membranes is a key factor in the absorption and distribution of drugs, drug permeation characteristics of three oral suspensions of ciprofloxacin were designed and compared. The three suspensions of ciprofloxacin were prepared by taking biodegradable polymers such as carbopol 934, carbopol 940, and hydroxypropyl methylcellulose (HPMC). The permeability study was performed by using a Franz diffusion cell through both synthetic cellulose acetate membrane and excised goat gastrointestinal membranes in acidic as well as alkaline pH. To know the permeability of drug from control/formulations through different membranes in acidic/alkaline pH, cumulative percentage drug permeation, apparent permeability (Papp), flux, and enhancement ratio (ER) were calculated. Considering Papp and flux values of all formulations, it is evident that formulation containing HPMC was the most beneficial for improving permeation and diffusivity of ciprofloxacin even after 16 h. Hence, this preparation may be considered as the most suitable formulation to obtain prolonged release action of the drug. The ER values of all formulations, through excised goat intestinal mucosal membrane in alkaline pH, were higher than those formulations through goat stomach mucosal membrane in acidic pH. Enhancement ratio values of those formulations indicate that the permeability of the drug was more enhanced by the polymers in the intestinal part, leading to more bioavailability and prolonged action in that portion of the gastrointestinal tract. It may also be concluded from our results that HPMC containing formulation was the best suspension, which may show effective controlled release action. Even carbopol containing formulations might also produce controlled release action. PMID:25126536

  8. Permeability of lipid bilayers to amino acids and phosphate

    NASA Technical Reports Server (NTRS)

    Chakrabarti, A. C.; Deamer, D. W.

    1992-01-01

    Permeability coefficients for amino acid classes, including neutral, polar, hydrophobic, and charged species, were measured and compared with values for other ionic solutes such as phosphate. The rates of efflux of glycine, lysine, phenylalanine, serine and tryptophan were determined after they were passively entrapped in large unilamellar vesicles (LUVs) composed of egg phosphatidylcholine (EPC) or dimyristoylphosphatidylcholine (DMPC). The following permeability coefficients were obtained for: glycine, 5.7 x 10(-12) cm s-1 (EPC), 2.0 x 10(-11) cm s-1 (DMPC); serine, 5.5 x 10(-12) cm s-1 (EPC), 1.6 x 10(-11) cm s-1 (DMPC); lysine, 5.1 x 10(-12) cm s-1 (EPC), 1.9 x 10(-11) cm s-1 (DMPC); tryptophan, 4.1 x 10(-10) cm s-1 (EPC); and phenylalanine, 2.5 x 10(-10) cm s-1 (EPC). Decreasing lipid chain length increased permeability slightly, while variations in pH had only minor effects on the permeability coefficients of the amino acids tested. Phosphate permeability was in the range of 10(-12)-10(-13) cm s-1 depending on the pH of the medium. The values for the polar and charged amino acids were surprisingly similar to those previously measured for monovalent cations such as sodium and potassium, which are in the range of 10(-12)-10(-13) cm s-1, depending on conditions and the lipid species used. This observation suggests that the permeation rates for the neutral, polar and charged amino acids are controlled by bilayer fluctuations and transient defects, rather than partition coefficients and Born energy barriers. The results are relevant to the permeation of certain peptides into lipid bilayers during protein translocation and membrane biogenesis.

  9. Acid tolerance, proton permeabilities, and membrane ATPases of oral streptococci.

    PubMed Central

    Bender, G R; Sutton, S V; Marquis, R E

    1986-01-01

    Differences in acid tolerance among representative oral streptococci were found to be related more closely to the dynamic permeabilities of the bacteria to protons than to differences in the sensitivities of cell membranes to gross damage caused by environmental acidification. For Streptococcus mutans GS-5, Streptococcus sanguis NCTC 10904, and Streptococcus salivarius ATCC 13419, gross membrane damage, indicated by the release of magnesium from whole cells, occurred at pH values below about 4 and was rapid and extensive at pH values of about 3 or less. A more aciduric, lactic acid bacterium, Lactobacillus casei ATCC 4646, was more resistant to environmental acidification, and gross membrane damage was evident only at pH values below 3. Assessments of the movements of protons into S. mutans cells after an acid pulse at various pH values indicated that permeability to protons was minimal at a pH value of about 5, at which the average half time for pH equilibration across the cell membrane was about 12 min. The corresponding values for the less aciduric organism S. sanguis were pH 7 and 8.2 min, and the values for the intermediate organism S. salivarius were pH 6 and 6.6 min. The ATPase inhibitor dicyclohexylcarbodiimide acted to increase markedly the permeability of each organism to protons, and this action indicated that permeability involved not only the passive inflow of protons but also active outflow through the proton-translocating membrane ATPase. Membranes were isolated from each of the bacteria, and pH profiles for ATPase activities indicated pH optima of about 7.5, 7.0, 6.0, and 5.0 for S. sanguis, S. salivarius, S. mutans, and L. casei, respectively. Thus, the pH profiles for the enzymes reflected the acid tolerances of the bacteria and the permeabilities of whole cells to protons. PMID:3015800

  10. Intestinal permeability defects: Is it time to treat?

    PubMed Central

    Odenwald, Matthew A.; Turner, Jerrold R.

    2013-01-01

    An essential role of the intestinal epithelium is to separate luminal contents from the interstitium, a function primarily determined by the integrity of the epithelium and the tight junction that seals the paracellular space. Intestinal tight junctions are selectively-permeable, and intestinal permeability can be increased physiologically in response to luminal nutrients or pathologically by mucosal immune cells and cytokines, the enteric nervous system, and pathogens. Compromised intestinal barrier function is associated with an array of clinical conditions, both intestinal and systemic. While most available data are correlative, some studies support a model where cycles of increased intestinal permeability, intestinal immune activation, and subsequent immune-mediated barrier loss contribute to disease progression. This model is applicable to intestinal and systemic diseases. However, it has not been proven and both mechanistic and therapeutic studies are ongoing. Nevertheless, the correlation between increased intestinal permeability and disease has caught the attention of the public, leading to a rise in popularity of the diagnosis of “leaky gut syndrome,” which encompasses a range of systemic disorders. Proponents claim that barrier restoration will cure underlying disease, but this has not been demonstrated in clinical trials. Moreover, human and mouse studies show that intestinal barrier loss alone is insufficient to initiate disease. It is therefore uncertain if increased permeability in these patients is a cause or effect of the underlying disorder. Although drug targets that may mediate barrier restoration have been proposed, none have been proven effective. As such, current treatments for barrier dysfunction should target the underlying disease. PMID:23851019

  11. Tritium Permeability of Incoloy 800H and Inconel 617

    SciTech Connect

    Philip Winston; Pattrick Calderoni; Paul Humrickhouse

    2012-07-01

    Design of the Next Generation Nuclear Plant (NGNP) reactor and its high-temperature components requires information regarding the permeation of fission generated tritium and hydrogen product through candidate heat exchanger alloys. Release of fission-generated tritium to the environment and the potential contamination of the helium coolant by permeation of product hydrogen into the coolant system represent safety basis and product contamination issues. Of the three potential candidates for high-temperature components of the NGNP reactor design, only permeability for Incoloy 800H has been well documented. Hydrogen permeability data have been published for Inconel 617, but only in two literature reports and for partial pressures of hydrogen greater than one atmosphere, far higher than anticipated in the NGNP reactor. To support engineering design of the NGNP reactor components, the tritium permeability of Inconel 617 and Incoloy 800H was determined using a measurement system designed and fabricated at Idaho National Laboratory. The tritium permeability of Incoloy 800H and Inconel 617, was measured in the temperature range 650 to 950°C and at primary concentrations of 1.5 to 6 parts per million volume tritium in helium. (partial pressures of 10-6 atm)—three orders of magnitude lower partial pressures than used in the hydrogen permeation testing. The measured tritium permeability of Incoloy 800H and Inconel 617 deviated substantially from the values measured for hydrogen. This may be due to instrument offset, system absorption, presence of competing quantities of hydrogen, surface oxides, or other phenomena. Due to the challenge of determining the chemical composition of a mixture with such a low hydrogen isotope concentration, no categorical explanation of this offset has been developed.

  12. Permeability of Candidate Stirling Heater Head Materials Measured

    NASA Technical Reports Server (NTRS)

    Freedman, Marc R.; Singh, Mrityunjay

    2005-01-01

    Researchers at the NASA Glenn Research Center are evaluating high-temperature materials for Stirling heater heads for second- and third-generation Stirling radioisotope power systems that would help to increase the system efficiency to 30 to 35 percent and the system specific power to 8 to 10+ W/kg. Ceramic materials could make it possible for the convertor hot-end temperature to be increased to 1050 to 1200 C, in comparison to the current 650 C with an Inconel 718 heater head. A hermetically sealed Stirling heater head must retain a constant internal pressure of nearly 400-psi helium (He) throughout its useful life (120,000 hr) at the design operating temperature. Therefore, He permeability was measured for eight potential materials and compared with the permeability of the current heater head material, Inconel 718. The eight materials included silicon nitride (Si3N4), silicon dioxide (SiO2), both sintered and chemical vapor deposited (CVD) silicon carbide (SiC), alumina (Al2O3), two types of melt-infiltrated (MI) SiC/SiC composites, and a carbon/SiC composite (C/SiC). Glenn submitted samples of each material to Porous Materials, Inc., Ithaca, New York, for permeability analysis. At room temperature and 30-psi He, four materials--Si3N4, Al2O3, SiO2, and sintered SiC--demonstrated lower permeability than Inconel 718. The CVD SiC and all the composite materials were significantly more permeable to He than the baseline material.

  13. The permeability of gabbro in oceanic core complexes

    NASA Astrophysics Data System (ADS)

    Titarenko, S.; McCaig, A. M.

    2013-12-01

    In IODP Expedition 340T, a thermal gradient of about 100 °C km-1 was measured in IODP Hole U1309D (Blackman et al. 2013), located in 1.2 My old gabbroic crust in the footwall of an oceanic detachment fault in the Atlantis Massif, just west of the mid-Atlantic Ridge at 30° N. The gradient is linear below 748 mbsf, indicating an essentially conductive regime, and slightly concave above that depth, suggesting slow, long-term downward flow of seawater in surrounding rocks. The lack of any vigorous hydrothermal circulation at this site is remarkable considering that the serpentinite-hosted Lost City Hydrothermal Field (LCHF) is located only 5 km to the south, and has been venting highly alkaline fluids at 40-90 °C for at least the last 140,000 years. We have created a 2-D topographic model of the Atlantis Massif using a N-S profile through the LCHF and the drillhole location, and modelled hydrothermal circulation using Comsol Multiphysics. A maximum permeability of 10-17 m2 below 750 mbsf, and a basal heatflow of 0.22 Wm-1 are required at the drillhole location to suppress hydrothermal circulation and preserve the observed conductive thermal gradient at depth. The concave gradient above this depth can be closely fitted over long time periods with a layer 750 m thick of higher permeability, ~3x 10-14 m2. Fluid vents at the site of the LCHF and in a small knoll north of the drill hole, and enters the seafloor everywhere else, including the drillhole location. Model vent temperatures are only about 20 °C however, much less that at the LCHF. A model with a deeper permeable zone beneath the LCHF, with a permeability of 10-15 m2 or more, is required to match simultaneously both observed vent temperatures and the drillhole gradient. This deep permeable zone is hosted in serpentinite but is most likely related to active faulting related to the Atlantis Transform Fault, not lithological control on permeability. Data from the flanks of both fast and intermediate spreading

  14. Technology Solutions Case Study: Moisture Durability of Vapor Permeable Insulating Sheathing

    SciTech Connect

    2013-10-01

    In this project, Building America team Building Science Corporation researched some of the ramifications of using exterior, vapor permeable insulation on retrofit walls with vapor permeable cavity insulation. Retrofit strategies are a key factor in reducing exterior building stock consumption.

  15. Morphine-Induced Preconditioning: Involvement of Protein Kinase A and Mitochondrial Permeability Transition Pore

    PubMed Central

    Dorsch, Marianne; Behmenburg, Friederike; Raible, Miriam; Blase, Dominic; Grievink, Hilbert; Hollmann, Markus W.; Heinen, André; Huhn, Ragnar

    2016-01-01

    Background Morphine induces myocardial preconditioning (M-PC) via activation of mitochondrial large conductance Ca2+-sensitive potassium (mKCa) channels. An upstream regulator of mKCa channels is protein kinase A (PKA). Furthermore, mKCa channel activation regulates mitochondrial bioenergetics and thereby prevents opening of the mitochondrial permeability transition pore (mPTP). Here, we investigated in the rat heart in vivo whether 1) M-PC is mediated by activation of PKA, and 2) pharmacological opening of the mPTP abolishes the cardioprotective effect of M-PC and 3) M-PC is critically dependent on STAT3 activation, which is located upstream of mPTP within the signalling pathway. Methods Male Wistar rats were randomised to six groups (each n = 6). All animals underwent 25 minutes of regional myocardial ischemia and 120 minutes of reperfusion. Control animals (Con) were not further treated. Morphine preconditioning was initiated by intravenous administration of 0.3 mg/kg morphine (M-PC). The PKA blocker H-89 (10 μg/kg) was investigated with and without morphine (H-89+M-PC, H-89). We determined the effect of mPTP opening with atractyloside (5 mg/kg) with and without morphine (Atr+M-PC, Atr). Furthermore, the effect of morphine on PKA activity was tested in isolated adult rat cardiomyocytes. In further experiments in isolated hearts we tested the protective properties of morphine in the presence of STAT3 inhibition, and whether pharmacological prevention of the mPTP-opening by cyclosporine A (CsA) is cardioprotective in the presence of STAT3 inhibition. Results Morphine reduced infarct size from 64±5% to 39±9% (P<0.05 vs. Con). H-89 completely blocked preconditioning by morphine (64±9%; P<0.05 vs. M-PC), but H-89 itself had not effect on infarct size (61±10%; P>0.05 vs. Con). Also, atractyloside abolished infarct size reduction of morphine completely (65±9%; P<0.05 vs. M-PC) but had no influence on infarct size itself (64±5%; P>0.05 vs. Con). In isolated

  16. Fluids, fault zone permeability and two distinct types of pseudotachylyte

    NASA Astrophysics Data System (ADS)

    Bjornerud, M.

    2010-12-01

    The comparative rarity of pseudotachylyte in ancient fault zones is surprising in light of estimates that ca. 90% of the energy budget of an earthquake is expended in frictional heating. One explanation is that frictional melting (pseudotachylyte generation) is suppressed after the initial rupture on a fault zone because fluids infiltrate the zone and thermal pressurization of these fluids inhibits melting in subsequent seismic events. While this seems plausible for many of the iconic occurrences of pseudotachylyte in otherwise undamaged crystalline rocks, some pseudotachylytes clearly formed in host rocks in which permeability was apparently high and fluids were present at the time of frictional melting. In these fault zones, cataclasites and pseudotachylyte commonly have mutually cross cutting relationships, and both types of fault rock have been complexly intruded into the surrounding damage zone. In contrast, cataclasites associated with pseudotachylyte in pristine crystalline rocks occur in smaller volumes and have simpler geometries, typically limited to the margins of fault veins or in dilational jogs. These observations suggest that there may be two distinct physical circumstances under which frictional melting may occur and thus two distinct genetic types of pseudotachylyte. Classic “dry” pseudotachylytes (e.g., Holsnøy, Bergen Arcs, Norway; Gole Larghe Fault, Italy) probably represent the initial seismic rupture of intact, low-permeability rock at high effective stress in the absence of fluids. When fluids are present, however (e.g., central Otago, New Zealand; Nojima fault, Japan), the potential for frictional melting depends on the relative rates at which heat and fluids can escape from a fault zone. Geophysical models of dynamic weakening mechanisms during earthquakes (Rempel and Rice, JGR, 2006) show that thermal pressurization occurs when the hydraulic diffusivity is effectively less than thermal diffusivity, while melting occurs when thermal

  17. Anisotropy of Pore Structure and Permeability in Granite: Preliminary Results

    NASA Astrophysics Data System (ADS)

    Onishi, C. T.; Shimizu, I.; Mizoguchi, K.; Uehara, S.; Shimamoto, T.

    2001-12-01

    The permeability of rocks is sensitive to pore structures. In fault zones where brittle deformation dominates, connectivity of cracks is perhaps the most important factor to control the fluid permeability. The relationship between microstructure, porosity-pore structures and permeability were investigated, using drill core samples from the Toki Granite in Gifu Prefecture, Central Japan. Core samples taken from a borehole penetrating a fault strand of the Tsukiyoshi Fault at the depth of 700 m were used for analysis and measurements. The Toki Granite shows textural variations. For example, away from the fault zone, the granite is fresh, massive biotite granite. Toward the fault the granitic texture is largely destroyed, reflecting deformation due to fault movement, with extensive fracturing and development of calcite veins. The central part of the fault zone constitutes foliated ultra-cataclasites with a fine grained matrix. Microstructural observations indicate that fragmentation of crystals is the cause of grain size reduction in the fault zone and anisotropy in micro-crack development. The effective porosity of bulk samples measured by Helium pycnometer varies from 0.54% for unaltered fresh granite to over 5.4% for foliated cataclasite from the central part of the fault zone. The pore structures of the granite samples were visualized by the Laser Scanning Microscope (LSM). The samples were impregnated with low viscosity fluorescent resin under vacuum condition, and then observed by the LSM. Quasi 3-D images of pore structures were constructed from optical slices (confocal images) of thick sections. Micro-cracks in granites were successfully filled with the fluorescent resin. Micro-cracks were mainly observed at grain boundaries, and the intra and inter granular fractures. Permeability measurements were performed by a High Pressure Temperature (HPT) gas apparatus using the pore oscillation technique. Confining pressure was increased and then decreased in the range

  18. Nutrient infiltrate concentrations from three permeable pavement types.

    PubMed

    Brown, Robert A; Borst, Michael

    2015-12-01

    While permeable pavement is increasingly being used to control stormwater runoff, field-based, side-by-side investigations on the effects different pavement types have on nutrient concentrations present in stormwater runoff are limited. In 2009, the U.S. EPA constructed a 0.4-ha parking lot in Edison, New Jersey, that incorporated permeable interlocking concrete pavement (PICP), pervious concrete (PC), and porous asphalt (PA). Each permeable pavement type has four, 54.9-m(2), lined sections that direct all infiltrate into 5.7-m(3) tanks enabling complete volume collection and sampling. This paper highlights the results from a 12-month period when samples were collected from 13 rainfall/runoff events and analyzed for nitrogen species, orthophosphate, and organic carbon. Differences in infiltrate concentrations among the three permeable pavement types were assessed and compared with concentrations in rainwater samples and impervious asphalt runoff samples, which were collected as controls. Contrary to expectations based on the literature, the PA infiltrate had significantly larger total nitrogen (TN) concentrations than runoff and infiltrate from the other two permeable pavement types, indicating that nitrogen leached from materials in the PA strata. There was no significant difference in TN concentration between runoff and infiltrate from either PICP or PC, but TN in runoff was significantly larger than in the rainwater, suggesting meaningful inter-event dry deposition. Similar to other permeable pavement studies, nitrate was the dominant nitrogen species in the infiltrate. The PA infiltrate had significantly larger nitrite and ammonia concentrations than PICP and PC, and this was presumably linked to unexpectedly high pH in the PA infiltrate that greatly exceeded the optimal pH range for nitrifying bacteria. Contrary to the nitrogen results, the PA infiltrate had significantly smaller orthophosphate concentrations than in rainwater, runoff, and infiltrate from PICP

  19. Estimated bounds on rock permeability changes from THM Processes

    SciTech Connect

    Berge, P A; Blair, S C; Wang, H F

    1998-08-01

    We performed THM modeling to estimate bounds on permeability changes in the NFE. For our modeling, we used the TM three-dimensional (3-D) finite-difference code FLAC{sup 3D} version 2.0 (Itasca Consulting Group Inc. 1997) to compute changes in stress and displacement in an elastic model subjected to temperature changes over time. Output from TH modeling (Hardin et al., 1998, Chapter 3) using the code NUFT (Nitao 1993) provided the temperature changes for input to FLAC{sup 3D}. We then estimated how the stress changes could affect permeability. For this report, we chose to base our 3-D THM modeling on a coarser version of the 2-D model we ran for the work described in Chapter 4 of the Near-Field/Altered Zone Models Report (Hardin et al., 1998, Chapter 4). The grid and temperature field were based on those used by the TH code for 50 yr of heating for the reference Case 1 TH model calculated using Total System Performance Assessment-Viability Assessment (TSPA-VA) base-case properties, nominal infiltration, and a point-load repository design (Hardin et al., 1998, Chapter 3). The stress field rotated in the region between and below the drifts after 50 yr of heating. High vertical shear stresses were computed for these regions. The maximum computed displacement was about 7 cm, mainly vertical. Estimates of permeability changes were obtained by analyzing stresses, following a method we developed previously for 2-D models. In our 3-D modeling for this report, we only considered vertical and horizontal fractures. We extended our 2-D method to a simplified 3-D case. We conclude that widespread permeability enhancement is likely for fractures parallel to NS fracture set No.2, the vertical fractures that strike north-south, for regions above the drifts. In some regions just above the drifts, permeability may increase by a minimum of a factor of two and possibly more than a factor of four if slip also occurs along the vertical fractures in EW set No.1, the east-west fractures

  20. High temperature permeability in volcanic systems: An experimental approach

    NASA Astrophysics Data System (ADS)

    Chadderton, Amy; Sammonds, Peter; Meredith, Philip; Smith, Rosanna; Tuffen, Hugh

    2015-04-01

    The permeability of magma exerts a major influence on volcanic activity and we have long held the ability to experimentally determine the permeability of volcanic material via various techniques. These observations have provided the basis for numerous theories of magmatic degassing. Recent enhancements to the High Temperature Triaxial Deformation Cell (HTTDC) at UCL have enabled us to make permeability measurements on 25mm x 75mm core samples at elevated temperature and elevated hydrostatic pressure (Gaunt et al, 2013). Specifically, we present here the results of several suites of permeability data on samples of dome dacite from Mount St Helens volcano, measured under an effective pressure of 5 MPa (confining pressure of 10 MPa and pore fluid pressure of 5 MPa) and temperatures up to 900oC. Most recently, the capabilities of the HTTDC apparatus have been further extended to enable permeability measurements to be made during triaxial deformation of test samples under similar temperature and pressure conditions. Initial results from this entirely new methodology will also be presented. These new experimental results are being applied to enhance our understanding of the complex issue of silicic magma degassing. Two recent eruptions in Chile, at Chaitén Volcano in 2008-10 and at Cordón Caulle in 2011-12, allowed the first detailed observations of rhyolitic activity and provided previously hidden insights into the evolution of highly silicic eruptions. Both events exhibited simultaneous explosive and effusive activity, with both lava and ash plumes emitted from the same vent (Castro et al, 2014). The permeability of fracture networks that act as fluid flow pathways is key to such eruptive behaviour, and will be investigated systematically at magmatic temperatures and pressures in the presence of pore fluids, using our newly-developed experimental capability. Castro, J.M., Bindeman, I.N., Tuffen, H. and Schipper, I. (2014) EPSL 405, 52-61. Gaunt, H.E., Sammonds, P

  1. Stress Analysis and Permeability Testing of Cryogenic Composite Feed Line

    NASA Technical Reports Server (NTRS)

    Chu, Tsuchin Philip

    1999-01-01

    For the next generation Single-Stage-To-Orbit (SSTO) Reusable Launch Vehicle (RLV), the use of advanced composite materials is highly desirable and critical to the success of the mission. NASA Marshall Space Flight Center (MSFC) has been working with the aerospace industry for many years to develop and demonstrate the cryogenic composite propellant tanks and feed lines technologies. A 50.8-mm diameter composite feed line for the Clipper Graham (DCY.A) was developed and tested. The purpose of the program is to demonstrate the LH2 permeability, composite to composite and metal joints, as well as composite flange interface of the composite feed line. Stress analysis and permeability testing have been performed on this article. Recently, a larger composite feed line design is being investigated and developed at MSFC for potential use in future RLV. The diameter of the feed line is 203 mm and the overall length is approximately 2.2 meters. This one piece unlined feed line consists of three straight tubular sections joined by two 90 degree elbows. The material chosen is IM7/977-3 prepreg fabric. The lay-up pattern is [0/90, plus or minus 45]s and is built up to 18 plies to the flanges at both ends. A preliminary stress analysis has been conducted to identify potential critical stresses and to develop the finite element analysis (FEA) capability of composite feed lines. As expected, the critical stresses occurred at the rims of some flange holes and the onset of the tapered tubular sections. Further analysis is required to determine the loads, flange deflection, vibration, and combined maximum loads. Two permeability-testing apparatuses were also designed for both flat panel specimens and curved feed line sections after impact damage. A larger permeant gas exposed area is required to accurately determine the effect of impact damage on the permeability of the feed line materials. The flat panel tester was fabricated and assembled. Three test coupons were made of graphite

  2. Tensor Inversion of Intrinsic Permeabilities for Heterogeneous Reservoirs

    NASA Astrophysics Data System (ADS)

    Jiao, J.; Zhang, Y.

    2013-12-01

    An inverse method has been developed using hybrid formulations and coordinate transform techniques to simultaneously estimate multiple intrinsic permeability tensors (k), flow field, and boundary conditions for a heterogeneous reservoir under non-pumping or pumping conditions [Jiao & Zhang, 2013]. Unlike the objective-function-based approaches, the inverse method does not require forward flow simulations to assess the data-model misfits; thus the knowledge of reservoir boundary conditions is not needed. The method directly incorporates noisy observed data (i.e., fluid heads, Darcy fluxes, or well rates) at the measurement locations, without solving a boundary value problem. Given sufficient measurement data, it yields well-posed systems of equations that can be solved efficiently with coarse inverse grids and nonlinear optimization. When pumping and injection are active, the well rates can be used as measurements and subsurface flux sampling is not needed. Also, local grid refinement at the well locations is not needed for the inversion to succeed. The method is successfully tested for reservoir problems with regular and irregular geometries, different petrofacies patterns, and permeability anisotropy ratios. All problems yield stable solutions under increasing measurement errors. For a given set of the observation data, inversion accuracy is most affected by the permeability anisotropy ratio. Accuracy in estimating k is also affected by the flow pattern: within a given petrofacies, when the Darcy flux component is extremely small, the corresponding directional permeability perpendicular to streamlines becomes less identifiable. Finally, inversion is successful even if the location of the reservoir boundaries is unknown. In this case, the problem domain for inversion is defined by the location of the measurement data. Select problems are presented below in a set of figures and a table (the relevant quantities have a consistent set of units and are thus not labeled

  3. Permeability of noble gases through Kapton, butyl, nylon, and “Silver Shield”

    NASA Astrophysics Data System (ADS)

    Schowalter, Steven J.; Connolly, Colin B.; Doyle, John M.

    2010-04-01

    Noble gas permeabilities and diffusivities of Kapton, butyl, nylon, and "Silver Shield" are measured at temperatures between 22 and 115C. The breakthrough times and solubilities at 22C are also determined. The relationship of the room temperature permeabilities to the noble gas atomic radii is used to estimate radon permeability for each material studied. For the noble gases tested, Kapton and Silver Shield have the lowest permeabilities and diffusivities, followed by nylon and butyl, respectively.

  4. Stress state evaluation in low carbon and TRIP steels by magnetic permeability

    NASA Astrophysics Data System (ADS)

    Kouli, M.-E.; Giannakis, M.

    2016-03-01

    Magnetic permeability is an indicative factor for the steel health monitoring. The measurements of magnetic permeability lead to the evaluation of the stress state of any ferromagnetic steel. The magnetic permeability measurements were conducted on low carbon and TRIP steel samples, which were subjected to both tensile and compressive stresses. The results indicated a direct correlation of the magnetic permeability with the mechanical properties, the stress state and the microstructural features of the examined samples.

  5. Mitigating methane emissions and air intrusion in heterogeneous landfills with a high permeability layer.

    PubMed

    Jung, Yoojin; Imhoff, Paul T; Augenstein, Don; Yazdani, Ramin

    2011-05-01

    Spatially variable refuse gas permeability and landfill gas (LFG) generation rate, cracking of the soil cover, and reduced refuse gas permeability because of liquid addition can all affect CH(4) collection efficiency when intermediate landfill covers are installed. A new gas collection system that includes a near-surface high permeability layer beneath the landfill cover was evaluated for enhancing capture of LFG and mitigating CH(4) emissions. Simulations of gas transport in two-dimensional domains demonstrated that the permeable layer reduces CH(4) emissions up to a factor of 2 for particular spatially variable gas permeability fields. When individual macrocracks formed in the cover soil and the permeable layer was absent, CH(4) emissions increased to as much as 24% of the total CH(4) generated, double the emissions when the permeable layer was installed. CH(4) oxidation in the cover soil was also much more uniform when the permeable layer was present: local percentages of CH(4) oxidized varied between 94% and 100% across the soil cover with the permeable layer, but ranged from 10% to 100% without this layer for some test cases. However, the permeable layer had a minor effect on CH(4) emissions and CH(4) oxidation in the cover soil when the ratio of the gas permeability of the cover soil to the mean refuse gas permeability ≤ 0.05. The modeling approach employed in this study may be used to assess the utility of other LFG collection systems and management practices. PMID:20880688

  6. Permeability of Campi Flegrei magmas: examples from the Campanian Ignimbrite and Monte Nuovo eruptions

    NASA Astrophysics Data System (ADS)

    Polacci, Margherita; Bouvet de Maisonneuve, Caroline; Giordano, Daniele; Piochi, Monica; Mancini, Lucia; Degruyter, Wim; Bachmann, Olivier

    2014-05-01

    We performed permeability measurements on trachy-phonolitic pyroclastic products from the Campanian Ignimbrite and Monte Nuovo, two explosive eruptions from the active Campi Flegrei caldera, Southern Italy. Viscous (Darcian) permeability spans a wide range between 1.22x10-14 and 9.31x10-11 m2. Inertial (non-Darcian) permeability follows the same trend as viscous permeability: it increases as viscous permeability increases, highlighting the strong direct correlation between these two parameters. We observe that vesicularity does not exert a first order control on permeability: the Monte Nuovo scoria clasts are the most permeable samples but not the most vesicular; pumice clasts from the Campanian Ignimbrite proximal facies, whose vesicularity is comparable with that of Monte Nuovo scoriae, are instead the least permeable. In addition, we find that sample geometry exhibits permeability anisotropy as samples oriented parallel to vesicle elongation are more permeable than those oriented perpendicular. We compare our results with permeability values of volcanic products from effusive and explosive activity, and discuss the role of melt viscosity and crystallinity on magma permeability.

  7. 21 CFR 886.5918 - Rigid gas permeable contact lens care products.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Rigid gas permeable contact lens care products... contact lens care products. (a) Identification. A rigid gas permeable contact lens care product is a... rigid gas permeable contact lens. This includes all solutions and tablets used together with rigid...

  8. 21 CFR 886.5918 - Rigid gas permeable contact lens care products.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Rigid gas permeable contact lens care products... contact lens care products. (a) Identification. A rigid gas permeable contact lens care product is a... rigid gas permeable contact lens. This includes all solutions and tablets used together with rigid...

  9. 21 CFR 886.5918 - Rigid gas permeable contact lens care products.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Rigid gas permeable contact lens care products... contact lens care products. (a) Identification. A rigid gas permeable contact lens care product is a... rigid gas permeable contact lens. This includes all solutions and tablets used together with rigid...

  10. 21 CFR 886.5918 - Rigid gas permeable contact lens care products.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Rigid gas permeable contact lens care products... contact lens care products. (a) Identification. A rigid gas permeable contact lens care product is a... rigid gas permeable contact lens. This includes all solutions and tablets used together with rigid...

  11. 46 CFR 171.066 - Calculation of permeability for Type I subdivision.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 46 Shipping 7 2010-10-01 2010-10-01 false Calculation of permeability for Type I subdivision. 171... permeability for Type I subdivision. (a) Except as prescribed in paragraph (b) of this section, the following permeabilities must be used when doing the calculations required to demonstrate compliance with § 171.065(a),...

  12. 46 CFR 171.072 - Calculation of permeability for Type II subdivision.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 46 Shipping 7 2010-10-01 2010-10-01 false Calculation of permeability for Type II subdivision. 171... permeability for Type II subdivision. When doing calcualtions to show compliance with § 171.070, the following uniform average permeabilities must be assumed: (a) 85 percent in the machinery space. (b) 60 percent...

  13. Measuring School Boundary Permeability: The P.S.C.Q. Revised.

    ERIC Educational Resources Information Center

    Wiener, William K.

    This paper discusses the concept of school boundary permeability and describes the field testing and revision of the Parent-School Communities Questionnaire (PSCQ), a survey questionnaire designed to measure the permeability of school boundaries. The concept of permeability assumes that any social system, such as a school, is surrounded by a…

  14. Increased bladder permeability in interstitial cystitis/painful bladder syndrome

    PubMed Central

    Greenwood-Van Meerveld, Beverley; Wisniewski, Amy B.; VanGordon, Samuel; Lin, HsuehKung; Kropp, Bradley P.; Towner, Rheal A.

    2015-01-01

    The definition of interstitial cystitis (IC) has evolved over the years from being a well-defined entity characterized by diagnostic lesion (Hunner’s ulcer) in the urothelium to a clinical diagnosis by exclusion [painful bladder syndrome (PBS)]. Although the etiology is unknown, a central theme has been an association with increased permeability of the bladder. This article reviews the evidence for increased permeability being important to the symptoms of interstitial cystitis/painful bladder syndrome (IC/PBS) and in treating the disorder. Recent work showing cross-communication among visceral organs is also reviewed to provide a basis for understanding IC/PBS as a systemic disorder of a complex, interconnected system consisting of the bladder, bowel and other organs, nerves, cytokine-responding cells and the nervous system. PMID:26751576

  15. Are extrusive rhyolites produced from permeable foam eruptions?

    USGS Publications Warehouse

    Friedman, I.

    1989-01-01

    The permeable foam hypothesis is suggested by Eichelberger el al. (1986) to explain a major loss of water from rhyolithic magmas in the volcanic conduit. Evidence for the high-water content of the major portion of the magmas is herein examined and rejected. Eichelberger's hypothesis does not take into account the large (~2 orders of magnitude) viscosity change that would occur in the conduit as a result of water loss. It also requires that the permeable foam collapse and weld to form an obsidian that in thin section displays no evidence of the foam. An alternate hypothesis to explain the existence of small amounts of high water content rhyolite glasses in acid volcanoes is that rhyolite magmas are relatively dry (0.1-0.3% H2O) and that water enters the magma from the environment to produce a water-rich selvage which then is kneaded into the body of the magma. -Author

  16. Gravity Current in Horizontal Porous Media with A Permeability Gradient

    NASA Astrophysics Data System (ADS)

    Zheng, Zhong; Tsai, Peichun; Al-Housseiny, Talal; Stone, Howard; Complex Fluid Group Team

    2011-11-01

    We study the influence of a power-law porosity and permeability gradient on the front propagation of a gravity current in an unconfined porous media. We neglect mass transfer and surface tension on the interface. A similarity solution is found for the propagating front, which is different from the homogeneous case. Experiments have been performed using liquid pushing air in a Hele-Shaw cell with a constant gradient in gap thickness in the vertical direction. We measure the speed of the front and the shape of the interface. We observe a third layer of trapped air in the region where the permeability is low, while it appears that the propagating front still satisfies the similarity solution with a modified coefficient. This work is supported by a funding from Carbon Mitigation Initiative at Princeton University

  17. Fractal analysis of permeability near the wall in porous media

    NASA Astrophysics Data System (ADS)

    Liang, Mingchao; Yu, Boming; Li, Li; Yang, Shanshan; Zou, Mingqing

    2014-01-01

    In this paper, a fractal model for permeability of porous media is proposed based on Tamayol and Bahrami's method and the fractal theory for porous media. The proposed model is expressed as a function of the mean particle diameter, the length along the macroscopic pressure drop in the medium, porosity, fractal dimensions for pore space and tortuous capillaries, and the ratio of the minimum pore size to the maximum pore size. The relationship between the permeability near the wall and the dimensionless distance from the wall under different conditions is discussed in detail. The predictions by the present fractal model are in good agreement with available experimental data. The present results indicate that the present model may have the potential in comprehensively understanding the mechanisms of flow near the wall in porous media.

  18. Biopolymer system for permeability modification in porous media

    SciTech Connect

    Stepp, A.K.; Bryant, R.S.; Llave, F.M.

    1995-12-31

    New technologies are needed to reduce the current high rate of well abandonment. Improved sweep efficiency, reservoir conformance, and permeability modification can have a significant impact on oil recovery processes. Microorganisms can be used to selectively plug high-permeability zones to improve sweep efficiency and impart conformance control. Studies of a promising microbial system for polymer production were conducted to evaluate reservoir conditions in which this system would be effective. Factors which can affect microbial growth and polymer production include salinity, pH, temperature, divalent ions, presence of residual oil, and rock matrix. Flask tests and coreflooding experiments were conducted to optimize and evaluate the effectiveness of this system. Nuclear magnetic resonance imaging (NMRI) was used to visualize microbial polymer production in porous media. Changes in fluid distribution within the pore system of the core were detected.

  19. Control of Seed Coat Thickness and Permeability in Soybean 1

    PubMed Central

    Noodén, L. D.; Blakley, K. A.; Grzybowski, J. M.

    1985-01-01

    Although the seed coat, through its thickness and permeability, often regulates seed germination, very little is known about the control of its development. Using soybean (Glycine max [L.] Merrill) explants, podbearing cuttings in which defined solutions can be substituted for the roots, we have demonstrated that cytokinin and mineral nutrients moving through the xylem can control soybean seed coat development. Lack of cytokinin and minerals in the culture solution, causes a thicker, less permeable seed coat to develop. The seeds with thickened coats will imbibe water rapidly if scarified; furthermore, these scratched seeds also germinate and produce normal plants. Inasmuch as stress (e.g. drought) decreases mineral assimilation and cytokinin production by the roots, the resulting delay in germination could be an adaptive response to stress. PMID:16664447

  20. Mitochondrial Permeability Transition: New Findings and Persisting Uncertainties.

    PubMed

    Izzo, Valentina; Bravo-San Pedro, José Manuel; Sica, Valentina; Kroemer, Guido; Galluzzi, Lorenzo

    2016-09-01

    Several insults cause the inner mitochondrial membrane to abruptly lose osmotic homeostasis, hence initiating a regulated variant of cell death known as 'mitochondrial permeability transition' (MPT)-driven necrosis. MPT provides an etiological contribution to several human disorders characterized by the acute loss of post-mitotic cells, including cardiac and cerebral ischemia. Nevertheless, the precise molecular determinants of MPT remain elusive, which considerably hampers the development of clinically implementable cardio- or neuroprotective strategies targeting this process. We summarize recent findings shedding new light on the supramolecular entity that mediates MPT, the so-called 'permeability transition pore complex' (PTPC). Moreover, we discuss hitherto unresolved controversies on MPT and analyze the major obstacles that still preclude the complete understanding and therapeutic targeting of this process. PMID:27161573

  1. Reduction of permeability in granite at elevated temperatures.

    PubMed

    Moore, D E; Lockner, D A; Byerlee, J D

    1994-09-01

    The addition of hydrothermal fluids to heated, intact granite leads to permeability reductions in the temperature range of 300 degrees to 500 degrees C, with the rate of change generally increasing with increasing temperature. The addition of gouge enhances the rate of permeability reduction because of the greater reactivity of the fine material. Flow rate is initially high in a throughgoing fracture but eventually drops to the level of intact granite. These results support the fault-valve model for the development of mesothermal ore deposits, in which seals are formed at the base of the seismogenic zone of high-angle thrust faults. The lower temperature results yield varying estimates of mineral-sealing rates at shallower depths in fault zones, although they generally support the hypothesis that such seals develop in less time than the recurrence interval for moderate to large earthquakes on the San Andreas fault. PMID:17801532

  2. Effect of drying on viscoelasticity and permeability of gel

    SciTech Connect

    Scherer, G.W.

    1994-12-31

    The beam-bending method was used to measure the effect of partial drying on the viscoelastic relaxation behavior and permeability of a two-step acid-base catalyzed silica gel. Both the elastic modulus (E) and the permeability (D) showed a power-law dependence on density ({rho}): E {approximately} {rho}{sup m} {approx} 3.0; D {approximately} {rho}{sup {minus}n}, n {approx} 2.5. The viscosity of the network rose from {approximately}10{sup 11} to {approximately}10{sup 13} Pa{center_dot}s, and was strongly dependent on age as well as density of the gel. The viscoelastic relaxation function was well described by the stretched exponential function with an exponent of 0.3--0.5.

  3. Spontaneous Imbibition in Low Permeability Medium, SUPRI TR-114

    SciTech Connect

    Kovscek, Anthony R.; Schembre, Josephina

    1999-08-09

    A systematic experimental investigation of capillary pressure characteristics and fluid flow in diatomite was begun. Using an X-ray CT scanner and a specially constructed imbibition cell, we study spontaneous water imbibition processes in diatomite and, for reference, Berea sandstone and chalk. The mass of water imbibed as a function of time is also measured. Imbibition is restricted to concurrent flow. Despite a marked difference in rock properties such as permeability and porosity, we find similar trends in saturation profiles and weight gain versus time functions. Imbibition in diatomote is relatively rapid when initial water saturation is low due to large capillary forces. Using a non-linear regression analysis together with the experimental data, the capillary pressure and water relative permeability curves are determined for the diatomite in the water-air system. The results given for displacement profiles by numerical simulation match the experimental results.

  4. Thermal treatment of low permeability soils using electrical resistance heating

    SciTech Connect

    Udell, K.S.

    1996-08-01

    The acceleration of recovery rates of second phase liquid contaminants from the subsurface during gas or water pumping operations is realized by increasing the soil and ground water temperature. Electrical heating with AC current is one method of increasing the soil and groundwater temperature and has particular applicability to low permeability soils. Several mechanisms have been identified that account for the enhanced removal of the contaminants during electrical heating. These are vaporization of liquid contaminants with low boiling points, temperature-enhanced evaporation rates of semi-volatile components, and removal of residual contaminants by the boiling of residual water. Field scale studies of electrical heating and fluid extraction show the effectiveness of this technique and its applicability to contaminants found both above and below the water table and within low permeability soils. 10 refs., 8 figs.

  5. Analysis of thermally induced permeability enhancement in geothermal injection wells

    SciTech Connect

    Benson, S.M.; Daggett, J.S.; Iglesias, E.; Arellano, V.; Ortiz-Ramirez, J.

    1987-02-01

    Reinjection of spent geothermal brine is a common means of disposing of geothermal effluents and maintaining reservoir pressures. Contrary to the predictions of two-fluid models (two-viscosity) of nonisothermal injection, an increase of injectivity, with continued injection, is often observed. Injectivity enhancement and thermally-affected pressure transients are particularly apparent in short-term injection tests at the Los Azufres Geothermal Field, Mexico. During an injection test, it is not uncommon to observe that after an initial pressure increase, the pressure decreases with time. As this typically occurs far below the pressure at which hydraulic fracturing is expected, some other mechanism for increasing the near-bore permeability must explain the observed behavior. This paper focuses on calculating the magnitude of the nearbore permeability changes observed in several nonisothermal injection tests conducted at the Los Azufres Geothermal Field.

  6. Structural permeability of complex networks to control signals

    NASA Astrophysics Data System (ADS)

    Lo Iudice, Francesco; Garofalo, Franco; Sorrentino, Francesco

    2015-09-01

    Many biological, social and technological systems can be described as complex networks. The goal of affecting their behaviour has motivated recent work focusing on the relationship between the network structure and its propensity to be controlled. While this work has provided insight into several relevant problems, a comprehensive approach to address partial and complete controllability of networks is still lacking. Here, we bridge this gap by developing a framework to maximize the diffusion of the control signals through a network, while taking into account physical and economic constraints that inevitably arise in applications. This approach allows us to introduce the network permeability, a unified metric of the propensity of a network to be controllable. The analysis of the permeability of several synthetic and real networks enables us to extract some structural features that deepen our quantitative understanding of the ease with which specific controllability requirements can be met.

  7. Novel JAK1-selective benzimidazole inhibitors with enhanced membrane permeability.

    PubMed

    Kim, Hyungmi; Kim, Mi Kyoung; Choo, Hyunah; Chong, Youhoon

    2016-07-15

    The previously identified Janus kinase 1 (JAK1)-selective inhibitor, 1-(2-aminoethyl)-2-(piperidin-4-yl)-1H-benzo[d]imidazole-5-carboxamide (2), suffered from low cell permeability, which resulted in poor pharmacokinetic properties. In this study, by introducing less polar hydrogen bond donors at N(1) (a hydroxyalkyl or a methylaminoalkyl group) and C2 (a cyclohexanol group) positions, a series of novel benzimidazole derivatives were prepared, which exhibited selective JAK1 inhibitory activity (IC50 against JAK1=0.08-0.15μM; JAK1-selectivity=26-40 fold vs JAK2, 12-23 fold vs JAK3, and 38-54 fold vs Tyk2) along with significantly increased lipophilicity (3.3-15.8 times) as well as membrane permeability (6.3-12 times). PMID:27261178

  8. Hydrogen Permeability of Polymer Matrix Composites at Cryogenic Temperatures

    NASA Technical Reports Server (NTRS)

    Grenoble, Ray W.; Gates, Thomas S

    2005-01-01

    This paper presents experimental methods and results of an ongoing study of the correlation between damage state and hydrogen gas permeability of laminated composite materials under mechanical strains and thermal loads. A specimen made from IM-7/977-2 composite material has been mechanically cycled at room temperature to induce microcrack damage. Crack density and tensile modulus were observed as functions of number of cycles. Damage development was found to occur most quickly in the off-axis plies near the outside of the laminate. Permeability measurements were made after 170,000 cycles and 430,000 cycles. Leak rate was found to depend on applied mechanical strain, crack density, and test temperature.

  9. Influence of wall permeability on turbulent boundary-layer properties

    NASA Technical Reports Server (NTRS)

    Wilkinson, S. P.

    1983-01-01

    Experimental boundary-layer studies of a series of low pressure drop, permeable surfaces have been conducted to characterize their surface interaction with a turbulent boundary layer. The models were flat and tested at nominally zero pressure gradient in low speed air. The surfaces were thin metal sheets with discrete perforations. Direct drag balance measurements of skin friction indicate that the general effect of surface permeability is to increase drag above that of a smooth plate reference level. Heuristic arguments are presented to show that this type of behavior is to be expected. Other boundary-layer data are also presented including mean velocity profiles and conditionally sampled streamwise velocity fluctuations (hot wire) for selected models.

  10. Tubular hydrogen permeable metal foil membrane and method of fabrication

    DOEpatents

    Paglieri, Stephen N.; Birdsell, Stephen A.; Barbero, Robert S.; Snow, Ronny C.; Smith, Frank M.

    2006-04-04

    A tubular hydrogen permeable metal membrane and fabrication process comprises obtaining a metal alloy foil having two surfaces, coating the surfaces with a metal or metal alloy catalytic layer to produce a hydrogen permeable metal membrane, sizing the membrane into a sheet with two long edges, wrapping the membrane around an elongated expandable rod with the two long edges aligned and overlapping to facilitate welding of the two together, placing the foil wrapped rod into a surrounding fixture housing with the two aligned and overlapping foil edges accessible through an elongated aperture in the surrounding fixture housing, expanding the elongated expandable rod within the surrounding fixture housing to tighten the foil about the expanded rod, welding the two long overlapping foil edges to one another generating a tubular membrane, and removing the tubular membrane from within the surrounding fixture housing and the expandable rod from with the tubular membrane.

  11. Structural permeability of complex networks to control signals

    PubMed Central

    Lo Iudice, Francesco; Garofalo, Franco; Sorrentino, Francesco

    2015-01-01

    Many biological, social and technological systems can be described as complex networks. The goal of affecting their behaviour has motivated recent work focusing on the relationship between the network structure and its propensity to be controlled. While this work has provided insight into several relevant problems, a comprehensive approach to address partial and complete controllability of networks is still lacking. Here, we bridge this gap by developing a framework to maximize the diffusion of the control signals through a network, while taking into account physical and economic constraints that inevitably arise in applications. This approach allows us to introduce the network permeability, a unified metric of the propensity of a network to be controllable. The analysis of the permeability of several synthetic and real networks enables us to extract some structural features that deepen our quantitative understanding of the ease with which specific controllability requirements can be met. PMID:26391186

  12. Use of Interface Treatment to Reduce Emissions from Residuals in Lower Permeability Zones to Groundwater flowing Through More Permeable Zones (Invited)

    NASA Astrophysics Data System (ADS)

    Johnson, P.; Cavanagh, B.; Clifton, L.; Daniels, E.; Dahlen, P.

    2013-12-01

    Many soil and groundwater remediation technologies rely on fluid flow for contaminant extraction or reactant delivery (e.g., soil vapor extraction, pump and treat, in situ chemical oxidation, air sparging, enhanced bioremediation). Given that most unconsolidated and consolidated settings have permeability contrasts, the outcome is often preferential treatment of more permeable zones and ineffective treatment of the lower permeability zones. When this happens, post-treatment contaminant emissions from low permeability zone residuals can cause unacceptable long-term impacts to groundwater in the transmissive zones. As complete remediation of the impacted lower permeability zones may not be practicable with conventional technologies, one might explore options that lead to reduction of the contaminant emissions to acceptable levels, rather than full remediation of the lower permeability layers. This could be accomplished either by creating a sustained emission reaction/attenuation zone at the high-low permeability interface, or by creating a clean soil zone extending sufficiently far into the lower permeability layer to cause the necessary reduction in contaminant concentration gradient and diffusive emission. These options are explored in proof-of-concept laboratory-scale physical model experiments. The physical models are prepared with two layers of contrasting permeability and either dissolved matrix storage or nonaqueous phase liquid (NAPL) in the lower permeability layer. A dissolved oxidant is then delivered to the interface via flow across the higher permeability layer and changes in contaminant emissions from the low permeability zone are monitored before, during, and after oxidant delivery. The use of three oxidants (dissolved oxygen, hydrogen peroxide and sodium persulfate) for treatment of emissions from petroleum hydrocarbon residuals is examined.

  13. Lipopolysaccharide-induced caveolin-1 phosphorylation-dependent increase in transcellular permeability precedes the increase in paracellular permeability

    PubMed Central

    Wang, Nan; Zhang, Dan; Sun, Gengyun; Zhang, Hong; You, Qinghai; Shao, Min; Yue, Yang

    2015-01-01

    Background Lipopolysaccharide (LPS) was shown to induce an increase in caveolin-1 (Cav-1) expression in endothelial cells; however, the mechanisms regarding this response and the consequences on caveolae-mediated transcellular transport have not been completely investigated. This study aims to investigate the role of LPS-induced Cav-1 phosphorylation in pulmonary microvascular permeability in pulmonary microvascular endothelial cells (PMVECs). Methods Rat PMVECs were isolated, cultured, and identified. Endocytosis experiments were employed to stain the nuclei by DAPI, and images were obtained with a fluorescence microscope. Permeability of endothelial cultures was measured to analyze the barrier function of endothelial monolayer. Western blot assay was used to examine the expression of Cav-1, pCav-1, triton-insoluble Cav-1, and triton-soluble Cav-1 protein. Results The LPS treatment induced phosphorylation of Cav-1, but did not alter the total Cav-1 level till 60 min in both rat and human PMVECs. LPS treatment also increased the triton-insoluble Cav-1 level, which peaked 15 min after LPS treatment in both rat and human PMVECs. LPS treatment increases the intercellular cell adhesion molecule-1 expression. Src inhibitors, including PP2, PP1, Saracatinib, and Quercetin, partially inhibited LPS-induced phosphorylation of Cav-1. In addition, both PP2 and caveolae disruptor MβCD inhibited LPS-induced increase of triton-insoluble Cav-1. LPS induces permeability by activating interleukin-8 and vascular endothelial growth factor and targeting other adhesion markers, such as ZO-1 and occludin. LPS treatment also significantly increased the endocytosis of albumin, which could be blocked by PP2 or MβCD. Furthermore, LPS treatment for 15 min significantly elevated Evans Blue-labeled BSA transport in advance of a decrease in transendothelial electrical resistance of PMVEC monolayer at this time point. After LPS treatment for 30 min, transendothelial electrical resistance

  14. Symmetry-Breaking Metamaterials Enabling Broadband Negative Permeability

    NASA Astrophysics Data System (ADS)

    Trang, Pham Thi; Nguyen, Bui Huu; Tiep, Dinh Hong; Thuy, Le Minh; Lam, Vu Dinh; Tung, Nguyen Thanh

    2016-05-01

    Looking for a metamaterial, which can operate over a broad frequency band, has been indispensable towards promising applications. In this report, we propose a simple approach, allowing enlargement of the negative permeability band by breaking the structural symmetry in conventional cut-wire-pair metamaterials. Equivalent LC circuit and finite integration simulations are performed to explain underlying physics of the band expansion. Microwave samples are also prepared and measured to verify the proposed idea.

  15. A Collection of Complex Permittivity and Permeability Measurements

    SciTech Connect

    Barry, W.; Byrd, J.; Johnson, J.; Smithwick, J.

    1993-02-01

    We present the results of measurements of the complex permittivity and permeability over a frequency range of 0.1-5.1 GHz for a range of microwave absorbing materials used in a variety of accelerator applications. We also describe the automated measurement technique which uses swept-frequency S-parameter measurements made on a strip transmission line device loaded with the material under test.

  16. Identification of productive layers in low-permeability gas wells

    SciTech Connect

    Johnston, J.L.; Lee, W.J. )

    1992-11-01

    This paper presents new guidelines for determining net pay thickness in low-permeability, multilayered gas wells. These criteria were developed from a sensitivity study performed with an analytical solution for complex multilayered reservoirs. The purpose of this study is to determine whether many layers now considered to contribute to net pay actually have transmissibilities too low for the layer to be productive, causing performance projections from current singly-layer descriptive models to be too optimistic.

  17. The effect of rotary instrumentation on the permeability of dentin

    SciTech Connect

    Boyer, D.B.; Svare, C.W.

    1981-06-01

    The filtration and diffusion of tritiated water through dentin disks were measured ina split-chamber diffusion cell. The dentin had been cut with a diamond disk and the surfaces modified with a carbide fissure bur or diamond bur. Disks were given a secondary burnishing treatment with a blank bur or a modified blank bur. Burnishing reduced the permeability of dentin cut with a fissure bur.

  18. Microwave techniques for measuring complex permittivity and permeability of materials

    SciTech Connect

    Guillon, P.

    1995-08-01

    Different materials are of fundamental importance to the aerospace, microwave, electronics and communications industries, and include for example microwave absorbing materials, antennas lenses and radomes, substrates for MMIC and microwave components and antennaes. Basic measurements for the complex permittivity and permeability of those homogeneous solid materials in the microwave spectral region are described including hardware, instrumentation and analysis. Elevated temperature measurements as well as measurements intercomparisons, with a discussion of the strengths and weaknesses of each techniques are also presented.

  19. Photoresponsive vesicle permeability based on intramolecular host-guest inclusion.

    PubMed

    Kauscher, Ulrike; Samanta, Avik; Ravoo, Bart Jan

    2014-01-28

    This article describes light-responsive vesicles that can release their contents in response to a light-sensitive molecular trigger. To this end, liposomes were equipped with amphiphilic β-cyclodextrin that was covalently labeled with azobenzene. Using dye encapsulation and confocal laser scanning microscopy, we show that the permeability of these vesicles strongly increases upon UV irradiation (λ = 350 nm) with concomitant isomerization of apolar trans-azobenzene to polar cis-azobenzene on the liposome surface. PMID:24287588

  20. Test device for measuring permeability of a barrier material

    DOEpatents

    Reese, Matthew; Dameron, Arrelaine; Kempe, Michael

    2014-03-04

    A test device for measuring permeability of a barrier material. An exemplary device comprises a test card having a thin-film conductor-pattern formed thereon and an edge seal which seals the test card to the barrier material. Another exemplary embodiment is an electrical calcium test device comprising: a test card an impermeable spacer, an edge seal which seals the test card to the spacer and an edge seal which seals the spacer to the barrier material.

  1. The hydrogen permeability of Pd{sub 4}S

    SciTech Connect

    O'Brien, Casey; Miller, James; Gellman, Andrew; Morreale, Bryan

    2011-04-01

    Hydrogen permeates rapidly through pure Pd membranes, but H{sub 2}S, a common minor component in hydrogen-containing streams, produces a Pd{sub 4}S film on the Pd surface that severely retards hydrogen permeation. Hydrogen still permeates through the bi-layered Pd{sub 4}S/Pd structure, indicating that the Pd{sub 4}S surface is active for H{sub 2} dissociation; the low hydrogen permeability of the Pd4S film is responsible for the decreased rate of hydrogen transport. In this work, the hydrogen permeability of Pd{sub 4}S was determined experimentally in the 623-773 K temperature range. Bi-layered Pd{sub 4}S/Pd foils were produced by exposing pure Pd foils to H{sub 2}S. H{sub 2} fluxes through the bi-layered Pd{sub 4}S/Pd foils were measured during exposure to both pure H{sub 2} and a 1000 ppm H{sub 2}S in H{sub 2} gas mixture. Our results show that H{sub 2}S slows hydrogen permeation through Pd mainly by producing a Pd{sub 4}S film on the Pd surface that is roughly an order-of-magnitude less permeable to hydrogen (k{sub Pd{sub 4}S} = 10{sup −7.5} exp(−0.22 eV/k{sub B}T) molH{sub 2}/m/s/Pa{sup 1/2}) than pure Pd. The presence of H{sub 2}S in the gas stream results in greater inhibition of hydrogen transport than can be explained by the very low permeability of Pd{sub 4}S. H{sub 2}S may block H2 dissociation sites at the Pd{sub 4}S surface.

  2. Relative ion permeability of normal and cystic fibrosis nasal epithelium.

    PubMed Central

    Knowles, M; Gatzy, J; Boucher, R

    1983-01-01

    The raised transepithelial electric potential difference (PD) across respiratory epithelia in cystic fibrosis (CF) has suggested an abnormality in ion permeation. We characterized this abnormality further by measuring in the nasal epithelia of CF and normal subjects the concentration-PD relationship for amiloride, an inhibitor of cell Na+ permeability, and PD responses to superfusion with solutions of different composition. Amiloride was more efficacious in the CF subjects but the ED50 was not different from that of normals (approximately 2 X 10(-6) M). Na+ replacement by choline induced effects similar to those of amiloride, i.e. a greater depolarization in CF subjects. A 10-fold increase in the K+ concentration of the perfusate induced a small (less than 10 mV) depolarization in both subject populations. When Cl- in the perfusate was replaced by gluconate or SO2-(4) the nasal PD of normal subjects hyperpolarized (lumen became more negative) by approximately 35 mV. A significantly smaller response (less than 17 mV) was induced in CF homozygotes but not in heterozygotes (38 mV). The smaller response of CF subjects appears to reflect an absolute decrease in luminal surface Cl- permeability because pretreatment with amiloride did not increase the response to Cl- free solution (7 mV). Accordingly, three abnormalities (decreased Cl- permeability, raised PD, greater amiloride efficacy) have been identified in CF respiratory epithelia. Whereas "excessive" active Na+ transport can account for these abnormalities and the dessication of airway surface liquid, it is possible that a lower lumenal cell membrane Cl- permeability and inhibition of a potential path of Cl- secretion can also explain the observations. PMID:6853720

  3. Bio-mediated Permeability Reduction of Saturated Sands

    NASA Astrophysics Data System (ADS)

    Proto, Clayton Joseph

    New, alternative in-situ ground improvement techniques are necessary to address increased performance demands and growing environmental concerns about traditional grouting methods. To date, the controlled use of microbiological processes has demonstrated promise in the ability of microbes to meet this need. A particular form of biological improvement is the utilization of biofilms, an organic accumulation of cells and extracellular polymeric substances (EPS), in saturated soils. By adhering and accumulating on particle surfaces, biofilms can cause clogging of the pore volume and induce significant permeability reductions. The void-filling nature of biofilms allows for possible field applications to control groundwater, heal leaks, and prevent internal erosion in structures such as earth dams and levees. This study investigated the growth characteristics and robustness of biofilm-treated sands. Experimental results indicate that biofilms are capable of reducing permeability of saturated sands by 100-fold or more after only two to three weeks of nutrient treatment. These improvements can be maintained indefinitely with extended nutrient treatments, after which a gradual return to initial conditions is seen. During periods of nutrient treatment, permeability reductions were shown to remain stable in a variety of adverse conditions including two months of starvation, reverse flow, and fluctuating hydraulic gradients. However, further tests indicated that biofilm growth in this study was highly heterogeneous, with the majority of clogging occurring adjacent to the inlet face. The results of this study show strong potential for the use of biofilms to reduce permeability, but future studies are required to improve uniformity as the process is scaled to field applications.

  4. Bioinspired nanovalves with selective permeability and pH sensitivity

    NASA Astrophysics Data System (ADS)

    Zheng, Z.; Huang, X.; Schenderlein, M.; Moehwald, H.; Xu, G.-K.; Shchukin, D. G.

    2015-01-01

    Biological systems with controlled permeability and release functionality, which are among the successful examples of living beings to survive in evolution, have attracted intensive investigation and have been mimicked due to their broad spectrum of applications. We present in this work, for the first time, an example of nuclear pore complexes (NPCs)-inspired controlled release system that exhibits on-demand release of angstrom-sized molecules. We do so in a cost-effective way by stabilizing porous cobalt basic carbonates as nanovalves and realizing pH-sensitive release of entrapped subnano cargo. The proof-of-concept work also consists of the establishment of two mathematical models to explain the selective permeability of the nanovalves. Finally, gram-sized (or larger) quantities of the bio-inspired controlled release system can be synthesized through a scaling-up strategy, which opens up opportunities for controlled release of functional molecules in wider practical applications.Biological systems with controlled permeability and release functionality, which are among the successful examples of living beings to survive in evolution, have attracted intensive investigation and have been mimicked due to their broad spectrum of applications. We present in this work, for the first time, an example of nuclear pore complexes (NPCs)-inspired controlled release system that exhibits on-demand release of angstrom-sized molecules. We do so in a cost-effective way by stabilizing porous cobalt basic carbonates as nanovalves and realizing pH-sensitive release of entrapped subnano cargo. The proof-of-concept work also consists of the establishment of two mathematical models to explain the selective permeability of the nanovalves. Finally, gram-sized (or larger) quantities of the bio-inspired controlled release system can be synthesized through a scaling-up strategy, which opens up opportunities for controlled release of functional molecules in wider practical applications

  5. Can the imaginary part of permeability be negative?

    PubMed

    Markel, Vadim A

    2008-08-01

    When new composite optical materials are developed experimentally or studied in numerical simulations, it is essential to have a set of fundamental constraints that the optical constants of such materials must satisfy. In this paper I argue that positivity of the imaginary part of the magnetic permeability may not be one of such constraints, particularly in naturally occurring diamagnetics and in artificial materials that exhibit diamagnetic response to low-frequency or static magnetic fields. PMID:18850963

  6. Depth-weighted, mean soil permeability in Kansas

    USGS Publications Warehouse

    Juracek, Kyle E.

    2000-01-01

    This digital spatial data set provides information on the magnitude and spatial pattern of depth-weighted, mean soil permeability throughout the State of Kansas. The data set was assembled using 1:24,000-scale cartographic and attribute information on the spatial distribution and characteristics of Kansas soils. The data set is in grid (raster) format with a grid-cell size of 10,000 square meters.

  7. Betacellulin Induces Increased Retinal Vascular Permeability in Mice

    PubMed Central

    Anand-Apte, Bela; Ebrahem, Quteba; Cutler, Alecia; Farage, Eric; Sugimoto, Masahiko; Hollyfield, Joe; Folkman, Judah

    2010-01-01

    Background Diabetic maculopathy, the leading cause of vision loss in patients with type 2 diabetes, is characterized by hyper-permeability of retinal blood vessels with subsequent formation of macular edema and hard exudates. The degree of hyperglycemia and duration of diabetes have been suggested to be good predictors of retinal complications. Intervention studies have determined that while intensive treatment of diabetes reduced the development of proliferative diabetic retinopathy it was associated with a two to three-fold increased risk of severe hypoglycemia. Thus we hypothesized the need to identify downstream glycemic targets, which induce retinal vascular permeability that could be targeted therapeutically without the additional risks associated with intensive treatment of the hyperglycemia. Betacellulin is a 32 kD member of the epidermal growth factor family with mitogenic properties for the retinal pigment epithelial cells. This led us to hypothesize a role for betacellulin in the retinal vascular complications associated with diabetes. Methods and Findings In this study, using a mouse model of diabetes, we demonstrate that diabetic mice have accentuated retinal vascular permeability with a concomitant increased expression of a cleaved soluble form of betacellulin (s-Btc) in the retina. Intravitreal injection of soluble betacellulin induced retinal vascular permeability in normoglycemic and hyperglycemic mice. Western blot analysis of retinas from patients with diabetic retinopathy showed an increase in the active soluble form of betacellulin. In addition, an increase in the levels of A disintegrin and metalloproteinase (ADAM)-10 which plays a role in the cleavage of betacellulin was seen in the retinas of diabetic mice and humans. Conclusions These results suggest that excessive amounts of betacellulin in the retina may contribute to the pathogenesis of diabetic macular edema. PMID:20976146

  8. Evaluation of dentin permeability after light activated internal dental bleaching.

    PubMed

    Carrasco, Laise Daniela; Zanello Guerisoli, Danilo M; Pécora, Jesus Djalma; Fröner, Izabel Cristina

    2007-02-01

    The aim of this in vitro study was to assess quantitatively the dentin permeability of human teeth after intracoronal bleaching therapy with 35% hydrogen peroxide activated by LEDs, halogen lamp or using the walking bleach technique. Forty human maxillary central incisors had standard access cavities performed and the cervical thirds of the canals were prepared with Gates-Glidden drills up to a size 130. Roots were resected between the coronal and middle thirds and the apical portions were discarded. A glass ionomer, 2 mm thick cervical plug was placed inside the canal, at the cement-enamel junction level. Group I received 35% hydrogen peroxide gel activated by LEDs. Group II was submitted to 35% hydrogen peroxide gel activated by halogen lamp. Group III received 35% hydrogen peroxide gel and the walking bleach technique was followed. Group IV (control) received a dry cotton pellet inside the pulp chamber with temporary restoration. Dentinal permeability was quantified by copper ion penetration. Linear measurements were obtained by analysis of digital images under x 5 magnification. Mean values and SD for the experimental groups were: I, 7.1% (+/-3.2%); II, 8.4% (+/-3.0%); III, 9.1% (+/-3.0%); IV, 1.3% (+/-2.8%). One-way ANOVA was used to analyze the results. Results showed an increase of permeability values for groups I, II and III when compared to group IV (control); however, no statistical differences were found between the three tested bleaching techniques. It can be concluded that 35% hydrogen peroxide activated by LED, halogen lamp or used following the walking bleach technique produced similar increase in dentinal permeability. PMID:17227378

  9. Permeability of Two Parachute Fabrics - Measurements, Modeling, and Application

    NASA Technical Reports Server (NTRS)

    Cruz, Juan R.; O'Farrell, Clara; Hennings, Elsa; Runnells, Paul

    2016-01-01

    Two parachute fabrics, described by Parachute Industry Specifications PIA-C-7020D Type I and PIA-C-44378D Type I, were tested to obtain their permeabilities in air (i.e., flow-through volume of air per area per time) over the range of differential pressures from 0.146 psf (7 Pa) to 25 psf (1197 Pa). Both fabrics met their specification permeabilities at the standard differential pressure of 0.5 inch of water (2.60 psf, 124 Pa). The permeability results were transformed into an effective porosity for use in calculations related to parachutes. Models were created that related the effective porosity to the unit Reynolds number for each of the fabrics. As an application example, these models were used to calculate the total porosities for two geometrically-equivalent subscale Disk-Gap-Band (DGB) parachutes fabricated from each of the two fabrics, and tested at the same operating conditions in a wind tunnel. Using the calculated total porosities and the results of the wind tunnel tests, the drag coefficient of a geometrically-equivalent full-scale DGB operating on Mars was estimated.

  10. Review of potential subsurface permeable barrier emplacement and monitoring technologies

    SciTech Connect

    Riggsbee, W.H.; Treat, R.L.; Stansfield, H.J.; Schwarz, R.M.; Cantrell, K.J.; Phillips, S.J.

    1994-02-01

    This report focuses on subsurface permeable barrier technologies potentially applicable to existing waste disposal sites. This report describes candidate subsurface permeable barriers, methods for emplacing these barriers, and methods used to monitor the barrier performance. Two types of subsurface barrier systems are described: those that apply to contamination.in the unsaturated zone, and those that apply to groundwater and to mobile contamination near the groundwater table. These barriers may be emplaced either horizontally or vertically depending on waste and site characteristics. Materials for creating permeable subsurface barriers are emplaced using one of three basic methods: injection, in situ mechanical mixing, or excavation-insertion. Injection is the emplacement of dissolved reagents or colloidal suspensions into the soil at elevated pressures. In situ mechanical mixing is the physical blending of the soil and the barrier material underground. Excavation-insertion is the removal of a soil volume and adding barrier materials to the space created. Major vertical barrier emplacement technologies include trenching-backfilling; slurry trenching; and vertical drilling and injection, including boring (earth augering), cable tool drilling, rotary drilling, sonic drilling, jetting methods, injection-mixing in drilled holes, and deep soil mixing. Major horizontal barrier emplacement technologies include horizontal drilling, microtunneling, compaction boring, horizontal emplacement, longwall mining, hydraulic fracturing, and jetting methods.

  11. Mitochondrial Calcium and the Permeability Transition in Cell Death

    PubMed Central

    Lemasters, John J.; Theruvath, Tom P.; Zhong, Zhi; Nieminen, Anna-Liisa

    2009-01-01

    Dysregulation of Ca2+ has long been implicated to be important in cell injury. A Ca2+-linked process important in necrosis and apoptosis (or necrapoptosis) is the mitochondrial permeability transition (MPT). In the MPT, large conductance permeability transition (PT) pores open that make the mitochondrial inner membrane abruptly permeable to solutes up to 1500 Da. The importance of Ca2+ in MPT induction varies with circumstance. Ca2+ overload is sufficient to induce the MPT. By contrast after ischemia-reperfusion to cardiac myocytes, Ca2+ overload is the consequence of bioenergetic failure after the MPT rather than its cause. In other models, such as cytotoxicity from Reye-related agents and storage-reperfusion injury to liver grafts, Ca2+ appears to be permissive to MPT onset. Lastly in oxidative stress, increased mitochondrial Ca2+ and ROS generation act synergistically to product the MPT and cell death. Thus, the exact role of Ca2+ for inducing the MPT and cell death depends on the particular biologic setting. PMID:19576166

  12. Human scalp permeability to the chemical warfare agent VX.

    PubMed

    Rolland, P; Bolzinger, M-A; Cruz, C; Briançon, S; Josse, D

    2011-12-01

    The use of chemical warfare agents such as VX in terrorism act might lead to contamination of the civilian population. Human scalp decontamination may require appropriate products and procedures. Due to ethical reasons, skin decontamination studies usually involve in vitro skin models, but human scalp skin samples are uncommon and expensive. The purpose of this study was to characterize the in vitro permeability to VX of human scalp, and to compare it with (a) human abdominal skin, and (b) pig skin from two different anatomic sites: ear and skull roof, in order to design a relevant model. Based on the VX skin permeation kinetics and distribution, we demonstrated that (a) human scalp was significantly more permeable to VX than abdominal skin and (b) pig-ear skin was the most relevant model to predict the in vitro human scalp permeability. Our results indicated that the follicular pathway significantly contributed to the skin absorption of VX through human scalp. In addition, the hair follicles and the stratum corneum significantly contributed to the formation of a skin reservoir for VX. PMID:21762776

  13. Modeling Fe0 permeable reactive barriers for groundwater remediation

    NASA Astrophysics Data System (ADS)

    Carniato, Luca; Schoups, Gerrit; Seuntjens, Piet; Bastiaens, Leen

    2010-05-01

    Remediation of groundwater pollution has traditionally been achieved by energy-intensive and drastic methods such as pump and treat (P&T) systems. Recently, more economically viable and less invasive methods such as permeable reactive barriers have been used to clean up a wide variety of groundwater pollutants (volatile organic compounds, VOCl). Permeable reactive barriers are installed in the subsurface and the naturally present hydraulic gradient makes the groundwater flow through the barrier where the contaminants are removed by different removal processes (biodegradation, sorption, precipitation, chemical destruction). Effective application of these techniques requires a solid understanding of the site-specific hydrogeological and biochemical conditions, as well as a predictive assessment of long-term remediation efficiency. For example, secondary mineral precipitation has been shown to reduce reactivity and efficiency of permeable reactive barriers and the interactions between biological and chemical processes may also influence the long-term efficiency of such systems. In this study a multi-component transport model based on PHAST USGS has been developed to simulate the removal processes in the barrier and to make quantitative predictions about the long-term efficiency of the system. In particular the modelling approach will be presented together with the model application in lab-scale experiments and in field.

  14. Computation of streaming potential in porous media: Modified permeability tensor

    NASA Astrophysics Data System (ADS)

    Bandopadhyay, Aditya; DasGupta, Debabrata; Mitra, Sushanta K.; Chakraborty, Suman

    2015-11-01

    We quantify the pressure-driven electrokinetic transport of electrolytes in porous media through a matched asymptotic expansion based method to obtain a homogenized description of the upscaled transport. The pressure driven flow of aqueous electrolytes over charged surfaces leads to the generation of an induced electric potential, commonly termed as the streaming potential. We derive an expression for the modified permeability tensor, K↔eff, which is analogous to the Darcy permeability tensor with due accounting for the induced streaming potential. The porous media herein are modeled as spatially periodic. The modified permeability tensor is obtained for both topographically simple and complex domains by enforcing a zero net global current. Towards resolving the complicated details of the porous medium in a computationally efficient framework, the domain identification and reconstruction of the geometries are performed using adaptive quadtree (in 2D) and octree (in 3D) algorithms, which allows one to resolve the solid-liquid interface as per the desired level of resolution. We discuss the influence of the induced streaming potential on the modification of the Darcy law in connection to transport processes through porous plugs, clays and soils by considering a case-study on Berea sandstone.

  15. Theoretical relationships between reactivity and permeability for monomineralic porous media

    SciTech Connect

    Smith, R.W.; Schafer, A.L.; Tompson, A.F.B.

    1996-08-01

    The release of contaminants to the subsurface has lead to potential or actual contamination of groundwater resources. The remediation of these plumes requires improved capability for the prediction of contaminant fate and transport. Key to improving predictive capabilities is an increased understanding of natural chemical (or reactive) heterogeneity in subsurface media and how chemical and physical heterogeneity are related. Although the effects of physical heterogeneity on transport has received significant attention, similar investigations of chemical heterogeneity, and the correlation of chemical and physical heterogeneity are in their infancy. Theoretical considerations for unconsolidated porous media composed of sand-sized grains of a single reactive phase suggest that chemical reactivity and permeability are inversely related. This correlation is consistent with measured permeability, porosity, and surface area data for unconsolidated sands. The correlation arises because both reactivity and permeability are functions of the surface area of the porous media. This relationship suggests that for a heterogeneous porous media, significant contaminant transport will occur in zones of minimal reactivity.

  16. A Microscopic Multiphase Diffusion Model of Viable Epidermis Permeability

    PubMed Central

    Nitsche, Johannes M.; Kasting, Gerald B.

    2013-01-01

    A microscopic model of passive transverse mass transport of small solutes in the viable epidermal layer of human skin is formulated on the basis of a hexagonal array of cells (i.e., keratinocytes) bounded by 4-nm-thick, anisotropic lipid bilayers and separated by 1-μm layers of extracellular fluid. Gap junctions and tight junctions with adjustable permeabilities are included to modulate the transport of solutes with low membrane permeabilities. Two keratinocyte aspect ratios are considered to represent basal and spinous cells (longer) and granular cells (more flattened). The diffusion problem is solved in a unit cell using a coordinate system conforming to the hexagonal cross section, and an efficient two-dimensional treatment is applied to describe transport in both the cell membranes and intercellular spaces, given their thinness. Results are presented in terms of an effective diffusion coefficient, D¯epi, and partition coefficient, K¯epi/w, for a homogenized representation of the microtransport problem. Representative calculations are carried out for three small solutes—water, L-glucose, and hydrocortisone—covering a wide range of membrane permeability. The effective transport parameters and their microscopic interpretation can be employed within the context of existing three-layer models of skin transport to provide more realistic estimates of the epidermal concentrations of topically applied solutes. PMID:23708370

  17. Increased intestinal permeability during cytomegalovirus infection in renal transplant recipients.

    PubMed

    de Maar, E F; Kleibeuker, J H; Boersma-van Ek, W; The, T H; van Son, W J

    1996-01-01

    Cytomegalovirus (CMV) infections in renal transplant recipients can affect the gastrointestinal tract, but significant clinical manifestations are seldom seen. We hypothesize that subclinical involvement of the gastrointestinal tract may be quite frequent during CMV infection. In order to study this, we measured intestinal permeability by calculating the urinary lactulose mannitol (LM) excretion ratio after oral administration of lactulose and mannitol (normal < 0.030) in patients with symptomatic and asymptomatic CMV infection. A total of 111 patients were enrolled in the study, 104 of whom were tested on postoperative day (POD) 10. Twenty-nine patients developed CMV infection, 12 of whom could be studied with the permeability test (median POD 40). Another nine patients without CMV infection were also studied at day 40 and served as controls. The LM ratio increased significantly during CMV infection compared to measurements before active infection (median 0.060 vs. 0.030, P < 0.01) and was significantly higher during the infection than in the control group (median 0.007, P < 0.01). No correlation could be found between the LM ratio and viral load, humoral response to the virus, or symptomatology of infection. We conclude that an increased intestinal permeability is found in a substantial number of patients with an active, albeit asymptomatic, CMV infection after renal transplantation. Pathophysiological mechanisms and clinical implications remain speculative but will be subject to further study. PMID:8914238

  18. Comment on 'Anisotropic permeability and tortuosity in deformed wet sediments'

    NASA Astrophysics Data System (ADS)

    Brown, Kevin M.; Moore, Casey

    1993-10-01

    As far as we can ascertain the only way of increasing the permeability parallel to shear zones developed in muds is to dilate them so that pore diameter r increases in conjuction to any grain alignment decrease in the value of T(sub x) Karig (1990) likewise suggested that dilational paths are necessary to account for the observed properties and fabrics in the decollements of an accretionary wedges. Because the sediments in the decollements of an accretionary wedge are progressively buried during their deformation and, thus subject to increasing overburden stress, dilational failure must be asscociated, at least episodically, with increased fluid pressures (Karig, 1990). We suggest that any such dilation will also be accompanied by an associated fault-parallel permeability enhancement. Whether the required 3-5 orders of permeability increase parallel to the fault zone that is suggested by hydrogeologic modeling (Screaton et al, 1990) can be accomplished by dilational deformation in partly consolidated sediments alone is not clear. The observation of local mineral-filled fractures in the muds of the decollement zone of the Barbados wedge (Macsle et al., 1988) Brown and Behrmann, 1990) suggests that conditions of extensional shear or hydrofracture development may periodically occur (Sibson, 1981). In this case, localized failure and dilation of the material in the decollements zone of accretionary wedges may occur as a prelude to such hydrofracture episodes.

  19. Wake control with permeable multilayer structures: The spherical symmetry case.

    PubMed

    Bowen, Patrick T; Smith, David R; Urzhumov, Yaroslav A

    2015-12-01

    We explore the possibility of controlling the wake and drag of a spherical object independently of each other, using radial distributions of permeability in the Brinkman-Stokes formalism. By discretizing a graded-permeability shell into discrete, macroscopically homogeneous layers, we are able to sample the entire functional space of spherically-symmetric permeabilities and observe quick convergence to a certain manifold in the wake-drag coordinates. Monte Carlo samplings with 10^{4}-10^{5} points have become possible thanks to our new algorithm, which is based on exact analytical solutions for the Stokes flow through an arbitrary multilayer porous sphere. The algorithm is not restricted to the Brinkman-Stokes equation and can be modified to account for other types of scattering problems for spherically-symmetric systems with arbitrary radial complexity. Our main practical finding for Stokes flow is that it is possible to reduce a certain measure of wake of a spherical object without any energy penalty and without active (power-consuming) force generation. PMID:26764826

  20. Microfluidic Fabrication of Pluronic Vesicles with Controlled Permeability.

    PubMed

    do Nascimento, Débora F; Arriaga, Laura R; Eggersdorfer, Max; Ziblat, Roy; Marques, Maria de Fátima V; Reynaud, Franceline; Koehler, Stephan A; Weitz, David A

    2016-05-31

    Block copolymers with a low hydrophilic-to-lipophilic balance form membranes that are highly permeable to hydrophilic molecules. Polymersomes with this type of membrane enable the controllable release of molecules without membrane rupture. However, these polymersomes are difficult to assemble because of their low hydrophobicity. Here, we report a microfluidic approach to the production of these polymersomes using double-emulsion drops with ultrathin shells as templates. The small thickness of the middle oil phase enables the attraction of the hydrophobic blocks of the polymers adsorbed at each of the oil/water interfaces of the double emulsions; this results in the dewetting of the oil from the surface of the innermost water drops of the double emulsions and the ultimate formation of the polymersome. This approach to polymersome fabrication enables control of the vesicle size and results in the efficient encapsulation of hydrophilic ingredients that can be released through the polymer membrane without membrane rupture. We apply our approach to the fabrication of Pluronic L121 vesicles and characterize the permeability of their membranes. Furthermore, we show that membrane permeability can be tuned by blending different Pluronic polymers. Our work thus describes a route to producing Pluronic vesicles that are useful for the controlled release of hydrophilic ingredients. PMID:27192611