Experimental study of heavy oil-water flow structure effects on relative permeabilities in a fracture filled with heavy oil

Energy Technology Data Exchange (ETDEWEB)

Shad, S.; Gates, I.D.; Maini, B.B. [Calgary Univ., AB (Canada). Dept. of Chemical and Petroleum Engineering]|[Alberta Ingenuity Centre for In Situ Energy, Edmonton, AB (Canada)

2008-10-15

An experimental apparatus was used to investigate the flow of water in the presence of heavy oil within a smooth-walled fracture. Different flow patterns were investigated under a variety of flow conditions. Results of the experiments were used to determine the accuracy of VC, Corey, and Shad and Gates models designed to represent the behaviour of oil wet systems. The relative permeability concept was used to describe the behaviour of multiple phases flowing through porous media. A smooth-walled plexiglass Hele-Shaw cell was used to visualize oil and water flow. Changes in flow rates led to different flow regimes. The experiment demonstrated that water flowed co-currently in the form of droplets or slugs. Decreases in the oil flow rate enlarged the size of the water droplets as well as the velocity, until eventually the droplets coalesced and became water slugs. Droplet appearance or disappearance directly impacted the oil and water saturation levels. Changes in fluid saturation altered the pressure gradient. Darcy's law for the 2 liquid phases were used to calculate relative permeability curves. The study showed that at low water saturation, oil relative permeability reached as high as 2.5, while water relative permeability was lower than unity. In the presence of a continuous water channel, water drops formed in oil, and the velocity of the drops was lower than their velocity under a discontinuous water flow regime. It was concluded that the Shad and Gates model overestimated oil relative permeability and underestimated water relative permeability. 38 refs., 2 tabs., 9 figs.

Experimental Measurement of Relative Permeability Functions for Fuel Cell GDL Materials

KAUST Repository

Hussaini, Irfan; Wang, Chao-Yang

2009-01-01

Gas diffusion layer in PEM fuel cells plays a pivotal role in water management. Modeling of liquid water transport through the GDL relies on knowledge of relative permeability functions in the in-plane and through-plane directions. In the present work, air and water relative permeabilities are experimentally determined as functions of saturation for typical GDL materials such as Toray-060, -090, -120 carbon paper and E-Tek carbon cloth materials in their plain, untreated forms. Saturation is measured using an ex-situ gravimetric method. Absolute and relative permeability functions in the two directions of interest are presented. Significant departure from the generally assumed cubic function of saturation is observed. ©The Electrochemical Society.

Effects of temperature, mechanical loading and of their interactions on the permeability of structural concrete

International Nuclear Information System (INIS)

Choinska, M.

2006-11-01

Concrete permeability may influence the durability of structures indirectly by controlling the penetration rate of aggressive agents, but also directly if the structure has a confinement role, like containment vessels of nuclear power plants for instance. In the industrial background on the safety of these structures, the objective of this study is to characterize the evolution of concrete permeability under the effects of temperature and mechanical loading. The permeability tests are performed on hollow concrete cylinders, subjected to temperature up to 150 C and compressive loading up to failure. Experimental results reveal that the effects of temperature and damage may be decoupled for the estimation of permeability and enable us to propose a relation between permeability, damage and temperature. However, this relation may only be applied in the pre-peak phase as concrete remains micro-cracked. In order to overcome this limit to be able to model also permeability increase in the post-peak phase, another parameter, which is crack opening, is introduced in the relation between permeability and damage. This problem, investigated by modelling, is exploited according to two approaches. The first one is based on the definition of a matching law between existing relations of permeability evolution with damage and with crack opening. With this approach the tendencies are similar to the observed ones on the experimental results. The second approach consists in linking from a mechanical point of view damage with crack opening in order to apply the Poiseuille's law for permeability determination. Experimental validation of this approach, emerging towards a continuous model capable to reproduce permeability variations of a concrete structure, constitutes a major perspective of this work. (author)

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

Energy Technology Data Exchange (ETDEWEB)

Lenormand, R.; Thiele, M.R. [Institut Francais du Petrole, Rueil Malmaison (France)

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.

Flow visualization and relative permeability measurements in rough-walled fractures

International Nuclear Information System (INIS)

Persoff, P.; Pruess, K.

1993-01-01

Two-phase (gas-liquid) flow experiments were done in a natural rock fracture and transparent replicas of natural fractures. Liquid was injected at constant volume flow rate, and gas was injected at either constant mass flow rate or constant pressure. When gas was injected at constant mass flow rate, the gas inlet pressure, and inlet and outlet capillary pressures, generally did not reach steady state but cycled irregularly. Flow visualization showed that this cycling was due to repeated blocking and unblocking of gas flow paths by liquid. Relative permeabilities calculated from flow rate and pressure data show that the sum of the relative permeabilities of the two phases is much less than 1, indicating that each phase interferes strongly with the flow of the other. Comparison of the relative permeability curves with typical curves for porous media (Corey curves) show that the phase interference is stronger in fractures than in typical porous media

A fractal model for predicting permeability and liquid water relative permeability in the gas diffusion layer (GDL) of PEMFCs

Science.gov (United States)

He, Guangli; Zhao, Zongchang; Ming, Pingwen; Abuliti, Abudula; Yin, Caoyong

In this study, a fractal model is developed to predict the permeability and liquid water relative permeability of the GDL (TGP-H-120 carbon paper) in proton exchange membrane fuel cells (PEMFCs), based on the micrographs (by SEM, i.e. scanning electron microscope) of the TGP-H-120. Pore size distribution (PSD), maximum pore size, porosity, diameter of the carbon fiber, pore tortuosity, area dimension, hydrophilicity or hydrophobicity, the thickness of GDL and saturation are involved in this model. The model was validated by comparison between the predicted results and experimental data. The results indicate that the water relative permeability in the hydrophobicity case is much higher than in the hydrophilicity case. So, a hydrophobic carbon paper is preferred for efficient removal of liquid water from the cathode of PEMFCs.

Relative permeabilities of supercritical CO2 and brine in carbon sequestration by a two-phase lattice Boltzmann method

Science.gov (United States)

Xie, Jian.-Fei.; He, S.; Zu, Y. Q.; Lamy-Chappuis, B.; Yardley, B. W. D.

2017-08-01

In this paper, the migration of supercritical carbon dioxide (CO2) in realistic sandstone rocks under conditions of saline aquifers, with applications to the carbon geological storage, has been investigated by a two-phase lattice Boltzmann method (LBM). Firstly the digital images of sandstone rocks were reproduced utilizing the X-ray computed microtomography (micro-CT), and high resolutions (up to 2.5 μm) were applied to the pore-scale LBM simulations. For the sake of numerical stability, the digital images were "cleaned" by closing the dead holes and removing the suspended particles in sandstone rocks. In addition, the effect of chemical reactions occurred in the carbonation process on the permeability was taken into account. For the wetting brine and non-wetting supercritical CO2 flows, they were treated as the immiscible fluids and were driven by pressure gradients in sandstone rocks. Relative permeabilities of brine and supercritical CO2 in sandstone rocks were estimated. Particularly the dynamic saturation was applied to improve the reliability of the calculations of the relative permeabilities. Moreover, the effects of the viscosity ratio of the two immiscible fluids and the resolution of digital images on the relative permeability were systematically investigated.

Relative permeability of fractured wellbore cement: an experimental investigation using electrical resistivity monitoring for moisture content

Science.gov (United States)

Um, W.; Rod, K. A.; Strickland, C. E.

2016-12-01

Permeability is a critical parameter needed to understand flow in subsurface environments; it is particularly important in deep subsurface reservoirs where multiphase fluid flow is common, such as carbon sequestration and geothermal reservoirs. Cement is used in the annulus of wellbores due to its low permeable properties to seal aquifers, reducing leaks to adjacent strata. Extreme subsurface environments of CO2 storage and geothermal production conditions will eventually reduce the cement integrity, propagating fracture networks and increasing the permeability for air and/or water. To date, there have been no reproducible experimental investigations of relative permeability in fractured wellbore cement published. To address this gap, we conducted a series of experiments using fractured Portland cement monoliths with increasing fracture networks. The monolith cylinder sides were jacketed with heavy-duty moisture-seal heat-shrink tubing, then fractured using shear force applied via a hydraulic press. Fractures were generated with different severity for each of three monoliths. Stainless steel endcaps were fixed to the monoliths using the same shrink-wrapped jacket. Fracture characteristics were determined using X-ray microtomography and image analysis. Flow controllers were used to control flow of water and air to supply continuous water or water plus air, both of which were delivered through the influent end cap. Effluent air flow was monitored using a flow meter, and water flow was measured gravimetrically. To monitor the effective saturation of the fractures, a RCON2 concrete bulk electrical resistivity test device was attached across both endcaps and a 0.1M NaNO3 brine was used as the transport fluid to improve resistivity measurements. Water content correlated to resistivity measurements with a r2 > 0.96. Data from the experiments was evaluated using two relative permeability models, the Corey-curve, often used for modeling relative permeability in porous media

Effect of temperature and relative humidity on the water vapour permeability and mechanical properties of cassava starch and soy protein concentrate based edible films.

Science.gov (United States)

Chinma, C E; Ariahu, C C; Alakali, J S

2015-04-01

The effect of temperature and relative humidity on the water vapour permeability (WVP) and mechanical properties of cassava starch and soy protein concentrate (SPC) based edible films containing 20 % glycerol level were studied. Tensile strength and elastic modulus of edible films increased with increase in temperature and decreased with increase in relative humidity, while elongation at break decreased. Water vapour permeability of the films increased (2.6-4.3 g.mm/m(2).day.kPa) with increase in temperature and relative humidity. The temperature dependence of water vapour permeation of cassava starch-soy protein concentrate films followed Arrhenius relationship. Activation energy (Ea) of water vapour permeation of cassava starch-soy protein concentrate edible films ranged from 1.9 to 5.3 kJ/mol (R (2)  ≥ 0.93) and increased with increase in SPC addition. The Ea values were lower for the bio-films than for polyvinylidene chloride, polypropylene and polyethylene which are an indication of low water vapour permeability of the developed biofilms compared to those synthetic films.

Gas and Water Permeability of Concrete

Energy Technology Data Exchange (ETDEWEB)

Villar, M. V.; Martin, P. L.; Romero, F. J.; Gutierrez-Rodirgo, V.; Barcala, J. M.

2012-11-01

The gas pressure of concrete samples was measured in an unsteady-state equipment working under low injection pressures and in a newly fine tuned steady-state setup working under different pressures. These measurements allowed the estimation of the intrinsic and relative gas permeability of the concrete and of the effect of boundary conditions on them. Permeability decreased with water content, but it was also greatly affected by the hydraulic history of concrete, i.e. if it had been previously dried or wetted. In particular, and for a given degree of saturation, the gas permeability of concrete previously saturated was lower than if the concrete had been just air dried or saturated after air drying. In any case, the gas permeability was about two orders of magnitude higher than the liquid water permeability (10-16 vs. 10-18 m2), probably due to the chemical reactions taking place during saturation (carbonation). The relative gas permeability of concrete increased sharply for water degrees of saturation smaller than 50%. The boundary conditions also affected the gas permeability, which seemed to be mostly conditioned by the back pressure and the confining pressure, increasing as the former increased and decreasing as the latter increased, i.e. decreasing as the effective pressure increased. Overall the increase of pressure head or injection pressure implied a decrease in gas permeability. External,microcracking during air-drying could not be ruled out as responsible for the decrease of permeability with confining pressure. The apparent permeability obtained applying the Klinkenberg method for a given effective pressure was only slightly smaller than the average of all the values measured for the same confining pressure range. For this reason it is considered that the Klinkenberg effect was not relevant in the range of pressures applied. (Author) 37 refs.

Effective stress law for the permeability and deformation of four porous limestones

Science.gov (United States)

Wang, Y.; Meng, F.; Wang, X.; Baud, P.; Wong, T. F.

2017-12-01

The effective stress behavior of a rock is related to the geometric of its pore space. In a microscopically homogeneous assemblage, effective stress coefficients for permeability, volumetric strain and porosity change are predicted to be equal to or less than unity. Experimental measurements are in basic agreement with this prediction, with exceptions particularly in clay-rich sandstones, for which effective stress coefficient for permeability up to 7 was documented. Little is known about carbonates, but Ghabezloo et al. [2009] studied the permeability of an oolitic limestone (from Nimes, France) with 17% porosity and reported effective stress coefficients up to 2.4. We investigated this phenomenon in Indiana, Leitha, Purbeck, and Thala limestones with porosities of 13-30%. Measurements were made at room temperature on water-saturated samples at confining and pore pressures of 7-15 MPa and 1-3 MPa, respectively. Unlike previous studies limited to the permeability, we also determined the effective stress coefficients for volumetric strain and porosity change. Indiana limestone is oolitic, and not surprisingly its behaviour was similar to Nimes limestone, with an effective stress coefficient for permeability of 2.5. Our Indiana limestone data showed that whereas the effective stress coefficient for volumetric strain was 1. Measurements on Purbeck and Thala limestones are consistent with these inequalities, with effective stress coefficients for permeability and porosity change >1 and that for volumetric strain <1. Even though Purbeck and Thala limestones are micritic with appreciable amount of quartz and dolomite, microstructural and mercury porosimetry data showed that their pore spaces are similar to the oolitic limestones, in that the pore size distribution is bimodal with significant fractions of both macropores and micropores. Berryman [1992] analyzed theoretically a rock made up of two porous constituents. Our new data are in agreement with inequalities he

Estimation of relative permeability and capillary pressure from mass imbibition experiments

Science.gov (United States)

Alyafei, Nayef; Blunt, Martin J.

2018-05-01

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

Measurement of relative permeability of fuel cell diffusion media

KAUST Repository

Hussaini, I.S.; Wang, C.Y.

2010-01-01

Gas diffusion layer (GDL) in PEM fuel cells plays a pivotal role in water management. Modeling of liquid water transport through the GDL relies on knowledge of relative permeability functions in the in-plane and through-plane directions

Permeability and stress-jump effects on magnetic drug targeting in a permeable microvessel using Darcy model

Energy Technology Data Exchange (ETDEWEB)

Shaw, S., E-mail: sachinshaw@gmail.com [Department of Mathematics and Statistical Sciences, Botswana International University of Science and Technology, Private Bag 16, Palapye (Botswana); Sutradhar, A.; Murthy, PVSN [Department of Mathematics, Indian Institute of Technology Kharagpur, Kharagpur 721302, West Bengal (India)

2017-05-01

In the present paper, we investigated the influence of permeability of the carrier particle and stress jump condition on the porous spherical surface in magnetic drug targeting through a permeable microvessel. The nature of blood is defined by non-Newtonian Casson fluid in the core region of the microvessel and Newtonian fluid in the peripheral region which is located near the surface of the wall of the microvessel. The magnetic particles are considered as spherical and in nanosize, embedded in the carrier particle along with drug particles. A magnet is placed near the tumor position to generate a magnetic field. The relative motion of the carrier particle is the resultant of the fluidic force, magnetic force and Saffman drag force which are calculated for the spherical carrier particle. Trajectories of the carrier particle along the radial and axial direction are calculated. Effect of different parameters such as stress-jump constant, permeability of the carrier particle, pressure gradient, yield stress, Saffman force, volume fraction of the embedded magnetic nanoparticles, permeability of the microvessel wall, and the radius of the carrier particle on the trajectory of the carrier particle are discussed and displayed graphically. - Highlights: • In the present manuscript, we considered the porous carrier particle which provide a larger surface area contact with the fluid than the solid spherical carrier particle. It shows that the porous carrier particle are captured easily than the solid carrier particle. • Introduce Suffman force on the carrier particle which commences an additional resistance which acts opposite to the surface wall and helps the particles to go away from the tumor position. • Considered stress jump condition at the surface of the porous carrier particle which enhanced the tendency of the carrier particle to be capture near the tumor. • Used Darcy model to define the permeability of the wall of the microvessel.

Evaluation of methods for measuring relative permeability of anhydride from the Salado Formation: Sensitivity analysis and data reduction

International Nuclear Information System (INIS)

Christiansen, R.L.; Kalbus, J.S.

1997-05-01

This report documents, demonstrates, evaluates, and provides theoretical justification for methods used to convert experimental data into relative permeability relationships. The report facilities accurate determination of relative permeabilities of anhydride rock samples from the Salado Formation at the Waste Isolation Pilot Plant (WIPP). Relative permeability characteristic curves are necessary for WIPP Performance Assessment (PA) predictions of the potential for flow of waste-generated gas from the repository and brine flow into repository. This report follows Christiansen and Howarth (1995), a comprehensive literature review of methods for measuring relative permeability. It focuses on unsteady-state experiments and describes five methods for obtaining relative permeability relationships from unsteady-state experiments. Unsteady-state experimental methods were recommended for relative permeability measurements of low-permeability anhydrite rock samples form the Salado Formation because these tests produce accurate relative permeability information and take significantly less time to complete than steady-state tests. Five methods for obtaining relative permeability relationships from unsteady-state experiments are described: the Welge method, the Johnson-Bossler-Naumann method, the Jones-Roszelle method, the Ramakrishnan-Cappiello method, and the Hagoort method. A summary, an example of the calculations, and a theoretical justification are provided for each of the five methods. Displacements in porous media are numerically simulated for the calculation examples. The simulated product data were processed using the methods, and the relative permeabilities obtained were compared with those input to the numerical model. A variety of operating conditions were simulated to show sensitivity of production behavior to rock-fluid properties

Effective High-Frequency Permeability of Compacted Metal Powders

Science.gov (United States)

Volkovskaya, I. I.; Semenov, V. E.; Rybakov, K. I.

2018-03-01

We propose a model for determination of the effective complex permeability of compacted metal-powder media. It is based on the equality of the magnetic moment in a given volume of the media with the desired effective permeability to the total magnetic moment of metal particles in the external high-frequency magnetic field, which arises due to excitation of electric eddy currents in the particles. Calculations within the framework of the proposed model allow us to refine the values of the real and imaginary components of the permeability of metal powder compacts in the microwave band. The conditions of applicability of the proposed model are formulated, and their fulfillment is verified for metal powder compacts in the microwave and millimeter wavelength bands.

Effect Of Hot Water Injection On Sandstone Permeability

DEFF Research Database (Denmark)

Rosenbrand, Esther; Fabricius, Ida Lykke

2012-01-01

of published results regarding the effect of temperature on sandstone permeability. These tests are performed with mineral oil, nitrogen gas, distilled water and solutions of NaCl, KCl, CaCl2 as well as brines that contain a mixture of salts. Thirteen sandstone formations, ranging from quartz arenites...... to formations with a significant fraction of fine particles including clay minerals are investigated. The porosities range from 0.10 to 0.30 and permeabilities span the range from 1 to 1000 md. To compare different rock types, specific surface is determined from permeability and porosity using Kozeny’s equation...... not account for all the permeability reductions observed. Permeablity reduction occurs both when distilled water is the saturating fluid as well as in tests with NaCl, KCl or CaCl2 solutions, however, this is not the case in tests with mineral oil or nitrogen gas. The formation of a filter cake or influx...

Optical investigation of effective permeability of dilute magnetic dielectrics with magnetic field

Science.gov (United States)

Banerjee, Ananya; Sarkar, A.

2016-05-01

The prime objective of this paper is to investigate the magnetic nature of dilute magnetic dielectrics (DMD) under variation of external magnetic field. The said variation is studied over developed nano-sized Gadolinium Oxide as a DMD system. The observed experimental field variation of the effective magnetic permeability is analyzed results of optical experiment. The experiment records the variation of Brewster angle of incident polarized LASER beam from the surface of developed DMD specimen with applied out of plane external magnetic field. The effective refractive index and hence relative magnetic permeability were estimated following electro-magnetic theory. The overall results obtained and agreement between theory and experiment are good.

Optical investigation of effective permeability of dilute magnetic dielectrics with magnetic field

Energy Technology Data Exchange (ETDEWEB)

Banerjee, Ananya, E-mail: banerjee.ananya2008@gmail.com; Sarkar, A. [Dept. of Physics, Bijoy Krishna Girls’ College, 5/3 M.G. Road, Howrah 711101, W.B. (India)

2016-05-06

The prime objective of this paper is to investigate the magnetic nature of dilute magnetic dielectrics (DMD) under variation of external magnetic field. The said variation is studied over developed nano-sized Gadolinium Oxide as a DMD system. The observed experimental field variation of the effective magnetic permeability is analyzed results of optical experiment. The experiment records the variation of Brewster angle of incident polarized LASER beam from the surface of developed DMD specimen with applied out of plane external magnetic field. The effective refractive index and hence relative magnetic permeability were estimated following electro-magnetic theory. The overall results obtained and agreement between theory and experiment are good.

Effect of leukotriene receptor antagonists on vascular permeability during endotoxic shock

International Nuclear Information System (INIS)

Cook, J.A.; Li, E.J.; Spicer, K.M.; Wise, W.C.; Halushka, P.V.

1990-01-01

Evidence has accumulated that sulfidopeptide leukotrienes are significant pathogenic mediators of certain hematologic and hemodynamic sequelae of endotoxic shock. In the present study, the effects of a selective LTD4/E4 receptor antagonist, LY171883 (LY), or a selective LTD4 receptor antagonist, SKF-104353 (SKF), were assessed on splanchnic and pulmonary localization of 99mTechnetium-labeled human serum albumin (99mTc-HSA) in acute endotoxic shock in the rat. Dynamic gamma camera imaging of heart (H), midabdominal (GI), and lung regions of interest generated time activity curves for baseline and at 5-35 min after Salmonella enteritidis endotoxin (10 mg/kg, i.v.). Slopes of GI/H and lung/H activity (permeability index, GI/H or lung/H X 10(-3)/min) provided indices of intestinal and lung localization. Rats received LY (30 mg/kg, i.v.), LY vehicle (LY Veh), SKF (10 mg/kg), or SKF vehicle (SK Veh) 10 min prior to endotoxin or endotoxin vehicle. In rats receiving the LY Veh and endotoxin (n = 8) or SKF Veh and endotoxin (n = 12), the splanchnic permeability indices to 99mTc-HSA were increased 11.2-fold and 5.1-fold, respectively (P less than 0.05) compared to vehicle control groups not given endotoxin (n = 5). Pulmonary permeability index for 99mTc-HSA was increased (P less than 0.05) to a lesser extent (3.2-fold) by endotoxin compared to vehicle controls. Pretreatment with SKF reduced the mesenteric permeability index to control levels (P less than 0.05) during the 5-35 min time interval post-endotoxin. LY reduced the mesenteric permeability index by 70%. Pulmonary relative permeability to 99mTc-HSA was not affected by LY pretreatment. Both splanchnic and lung relative permeability to the isotope was transient; at 135-225 min post-endotoxin, splanchnic localization of 99mTc-HSA (n = 4) was not significantly different from vehicle controls in these vascular beds

Permeability criteria for effective function of passive countercurrent multiplier.

Science.gov (United States)

Layton, H E; Knepper, M A; Chou, C L

1996-01-01

The urine concentrating effect of the mammalian renal inner medulla has been attributed to countercurrent multiplication of a transepithelial osmotic difference arising from passive absorption of NaCl from thin ascending limbs of long loops of Henle. This study assesses, both mathematically and experimentally, whether the permeability criteria for effective function of this passive hypothesis are consistent with transport properties measured in long loops of Henle of chinchilla. Mathematical simulations incorporating loop of Henle transepithelial permeabilities idealized for the passive hypothesis generated a steep inner medullary osmotic gradient, confirming the fundamental feasibility of the passive hypothesis. However, when permeabilities measured in chinchilla were used, no inner medullary gradient was generated. A key parameter in the apparent failure of the passive hypothesis is the long-loop descending limb (LDL) urea permeability, which must be small to prevent significant transepithelial urea flux into inner medullary LDL. Consequently, experiments in isolated perfused thin LDL were conducted to determine whether the urea permeability may be lower under conditions more nearly resembling those in the inner medulla. LDL segments were dissected from 30-70% of the distance along the inner medullary axis of the chinchilla kidney. The factors tested were NaCl concentration (125-400 mM in perfusate and bath), urea concentration (5-500 mM in perfusate and bath), calcium concentration (2-8 mM in perfusate and bath), and protamine concentration (300 micrograms/ml in perfusate). None of these factors significantly altered the measured urea permeability, which exceeded 20 x 10(-5) cm/s for all conditions. Simulation results show that this moderately high urea permeability in LDL is an order of magnitude too high for effective operation of the passive countercurrent multiplier.

Evaluating the Influence of Pore Architecture and Initial Saturation on Wettability and Relative Permeability in Heterogeneous, Shallow-Shelf Carbonates

Energy Technology Data Exchange (ETDEWEB)

Byrnes, Alan P.; Bhattacharya, Saibal; Victorine, John; Stalder, Ken

2007-09-30

Thin (3-40 ft thick), heterogeneous, limestone and dolomite reservoirs, deposited in shallow-shelf environments, represent a significant fraction of the reservoirs in the U.S. midcontinent and worldwide. In Kansas, reservoirs of the Arbuckle, Mississippian, and Lansing-Kansas City formations account for over 73% of the 6.3 BBO cumulative oil produced over the last century. For these reservoirs basic petrophysical properties (e.g., porosity, absolute permeability, capillary pressure, residual oil saturation to waterflood, resistivity, and relative permeability) vary significantly horizontally, vertically, and with scale of measurement. Many of these reservoirs produce from structures of less than 30-60 ft, and being located in the capillary pressure transition zone, exhibit vertically variable initial saturations and relative permeability properties. Rather than being simpler to model because of their small size, these reservoirs challenge characterization and simulation methodology and illustrate issues that are less apparent in larger reservoirs where transition zone effects are minor and most of the reservoir is at saturations near S{sub wirr}. These issues are further augmented by the presence of variable moldic porosity and possible intermediate to mixed wettability and the influence of these on capillary pressure and relative permeability. Understanding how capillary-pressure properties change with rock lithology and, in turn, within transition zones, and how relative permeability and residual oil saturation to waterflood change through the transition zone is critical to successful reservoir management and as advanced waterflood and improved and enhanced recovery methods are planned and implemented. Major aspects of the proposed study involve a series of tasks to measure data to reveal the nature of how wettability and drainage and imbibition oil-water relative permeability change with pore architecture and initial water saturation. Focus is placed on

Impact of Three-Phase Relative Permeability and Hysteresis Models on Forecasts of Storage Associated With CO2-EOR

Science.gov (United States)

Jia, Wei; McPherson, Brian; Pan, Feng; Dai, Zhenxue; Moodie, Nathan; Xiao, Ting

2018-02-01

Geological CO2 sequestration in conjunction with enhanced oil recovery (CO2-EOR) includes complex multiphase flow processes compared to CO2 storage in deep saline aquifers. Two of the most important factors affecting multiphase flow in CO2-EOR are three-phase relative permeability and associated hysteresis, both of which are difficult to measure and are usually represented by numerical interpolation models. The purpose of this study is to improve understanding of (1) the relative impacts of different three-phase relative permeability models and hysteresis models on CO2 trapping mechanisms, and (2) uncertainty associated with these two factors. Four different three-phase relative permeability models and three hysteresis models were applied to simulations of an active CO2-EOR site, the SACROC unit located in western Texas. To eliminate possible bias of deterministic parameters, we utilized a sequential Gaussian simulation technique to generate 50 realizations to describe heterogeneity of porosity and permeability, based on data obtained from well logs and seismic survey. Simulation results of forecasted CO2 storage suggested that (1) the choice of three-phase relative permeability model and hysteresis model led to noticeable impacts on forecasted CO2 sequestration capacity; (2) impacts of three-phase relative permeability models and hysteresis models on CO2 trapping are small during the CO2-EOR injection period, and increase during the post-EOR CO2 injection period; (3) the specific choice of hysteresis model is more important relative to the choice of three-phase relative permeability model; and (4) using the recommended three-phase WAG (Water-Alternating-Gas) hysteresis model may increase the impact of three-phase relative permeability models and uncertainty due to heterogeneity.

Relative permeability of the endothelium and epithelium of rabbit lungs

International Nuclear Information System (INIS)

Effros, R.M.; Mason, G.R.; Silverman, P.; Hukkanen, J.

1986-01-01

Electron micrographic studies of lungs suggest that the epithelial cells are more tightly joined than the underlying endothelium, and macromolecules penetrate the endothelium more readily than the epithelium. Comparisons of epithelial and endothelial permeability to small molecules have been based upon the relative rates at which solutes traverse the alveolar-capillary barrier in fluid filled lungs and those at which they equilibrate across the capillaries in air-filled lungs. Because the former process is much slower than the latter, it has been concluded that the epithelium is less permeable to small solutes than the endothelium. However this difference may be related to inadequate access of solutes to airway surfaces. In this study, solute losses from the vascular space were compared to those from the airspace in perfused, fluid-filled rabbit lungs. 36 Cl - and 125 I - were lost from air-spaces almost twice as rapidly as 22 Na + . In contrast, the endothelium is equally permeable to 22 Na + and these anions. Loss of 3 H-mannitol from the perfusate resembled that of 22 Na + for about 30 minutes, after which diffusion of 3 H-mannitol into the tissue nearly ceased. These observations suggest that the epithelium is more permselective than the endothelium. By resisting solute and water transport, the epithelium tends to prevent alveolar flooding and confines edema to the interstitium, where it is less likely to interfere with gas exchange

An Integrated Capillary, Buoyancy, and Viscous-Driven Model for Brine/CO2Relative Permeability in a Compositional and Parallel Reservoir Simulator

KAUST Repository

Kong, X.; Delshad, M.; Wheeler, M. F.

2012-01-01

The effectiveness of CO2 storage in the saline aquifers is governed by the interplay of capillary, viscous, and buoyancy forces. Recent experimental study reveals the impact of pressure, temperature, and salinity on interfacial tension (IFT) between CO2 and brine. The dependence of CO2-brine relative permeability and capillary pressure on pressure (IFT) is also clearly evident in published experimental results. Improved understanding of the mechanisms that control the migration and trapping of CO2 in subsurface is crucial to design future storage projects that warrant long-term and safe containment. Simulation studies ignoring the buoyancy and also variation in interfacial tension and the effect on the petrophysical properties such as trapped CO2 saturations, relative permeability, and capillary pressure have a poor chance of making accurate predictions of CO2 injectivity and plume migration. We have developed and implemented a general relative permeability model that combines effects of pressure gradient, buoyancy, and IFT in an equation of state (EOS) compositional and parallel simulator. The significance of IFT variations on CO2 migration and trapping is assessed.

An Integrated Capillary, Buoyancy, and Viscous-Driven Model for Brine/CO2Relative Permeability in a Compositional and Parallel Reservoir Simulator

KAUST Repository

Kong, X.

2012-11-03

The effectiveness of CO2 storage in the saline aquifers is governed by the interplay of capillary, viscous, and buoyancy forces. Recent experimental study reveals the impact of pressure, temperature, and salinity on interfacial tension (IFT) between CO2 and brine. The dependence of CO2-brine relative permeability and capillary pressure on pressure (IFT) is also clearly evident in published experimental results. Improved understanding of the mechanisms that control the migration and trapping of CO2 in subsurface is crucial to design future storage projects that warrant long-term and safe containment. Simulation studies ignoring the buoyancy and also variation in interfacial tension and the effect on the petrophysical properties such as trapped CO2 saturations, relative permeability, and capillary pressure have a poor chance of making accurate predictions of CO2 injectivity and plume migration. We have developed and implemented a general relative permeability model that combines effects of pressure gradient, buoyancy, and IFT in an equation of state (EOS) compositional and parallel simulator. The significance of IFT variations on CO2 migration and trapping is assessed.

Prediction of Central Nervous System Side Effects Through Drug Permeability to Blood-Brain Barrier and Recommendation Algorithm.

Science.gov (United States)

Fan, Jun; Yang, Jing; Jiang, Zhenran

2018-04-01

Drug side effects are one of the public health concerns. Using powerful machine-learning methods to predict potential side effects before the drugs reach the clinical stages is of great importance to reduce time consumption and protect the security of patients. Recently, researchers have proved that the central nervous system (CNS) side effects of a drug are closely related to its permeability to the blood-brain barrier (BBB). Inspired by this, we proposed an extended neighborhood-based recommendation method to predict CNS side effects using drug permeability to the BBB and other known features of drug. To the best of our knowledge, this is the first attempt to predict CNS side effects considering drug permeability to the BBB. Computational experiments demonstrated that drug permeability to the BBB is an important factor in CNS side effects prediction. Moreover, we built an ensemble recommendation model and obtained higher AUC score (area under the receiver operating characteristic curve) and AUPR score (area under the precision-recall curve) on the data set of CNS side effects by integrating various features of drug.

Effect of temperature on damage and permeability of clayey soils and rocks

International Nuclear Information System (INIS)

Monfared, M.

2011-04-01

Storage of exothermic radioactive waste in deep low permeability geological formations such as clayey rocks and plastic clays is a solution considered for long term repositories. However the excavation of underground galleries creates a damaged zone (EDZ). The effect of the damage zone on the transport properties of the geological barrier has been widely studied. Within the framework of the TIMODAZ European project, emphasis has been put on the effect of temperature. As a partner of this project, the current work is performed to investigate the coupling effect between temperature, damage and permeability on Boom clay and Opalinus clay through an experimental study. View to the experimental difficulties related to the low permeability materials, a new hollow cylinder triaxial cell with short drainage path specifically designed to study the thermo-hydro-mechanical behaviour of very low permeable materials is developed during this work. The tests and the numerical analysis show that the short sample drainage path reduces significantly the time needed to re-saturate an initially unsaturated sample and it also permits to achieve drained conditions (i.e. negligible excess pore pressure during testing) with a higher loading rate. For Boom clay, the effect of the pore water thermal pressurisation on a sample with a pre-existing shear band is investigated. The undrained heating under shear stress decreases the effective stress on the sample which leads to its failure. An existing failure plane in the sample behaves like a preferential weakness plane which can be reactivated by pore water thermal pressurisation. The estimated shearing resistance along the sheared plane is smaller than that of the intact material. For the Opalinus clay-stone, drained heating on a saturated sample shows that this clay-stone behaves like a slightly over consolidated material (thermo-elasto-plastic behaviour) with transition from expansion to contraction at 65 C. The decrease of the permeability

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

Science.gov (United States)

Li, Xiangchen; Yan, Xiaopeng; Kang, Yili

2018-04-01

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

Effect of vehicles and sodium lauryl sulphate on xenobiotic permeability and stratum corneum partitioning in porcine skin

International Nuclear Information System (INIS)

Merwe, Deon van der; Riviere, Jim E.

2005-01-01

Dermal contact with potentially toxic agricultural and industrial chemicals is a common hazard encountered in occupational, accidental spill and environmental contamination scenarios. Different solvents and chemical mixtures may influence dermal absorption. The effects of sodium lauryl sulphate (SLS) on the stratum corneum partitioning and permeability in porcine skin of 10 agricultural and industrial chemicals in water, ethanol and propylene glycol were investigated. The chemicals were phenol, p-nitrophenol, pentachlorophenol, methyl parathion, ethyl parathion, chlorpyrifos, fenthion, simazine, atrazine and propazine. SLS decreased partitioning into stratum corneum from water for lipophilic compounds, decreased partitioning from propylene glycol and did not alter partitioning from ethanol. SLS effects on permeability were less consistent, but generally decreased permeability from water, increased permeability from ethanol and had an inconsistent effect on permeability from propylene glycol. It was concluded that, for the compounds tested, partitioning into the stratum corneum was determined by the relative solubility of the solute in the donor solvent and the stratum corneum lipids. Permeability, however, reflected the result of successive, complex processes and was not predictable from stratum corneum partitioning alone. Addition of SLS to solvents altered partitioning and absorption characteristics across a range of compounds, which indicates that partition coefficients or skin permeability from neat chemical exposure should be used with caution in risk assessment procedures for chemical mixtures

Effect of confining pressure on permeability behavior of Beishan granite

International Nuclear Information System (INIS)

Ma Like; Li Yunfeng; Zhao Xingguang; Tan Guohuan

2012-01-01

By using of the Electro-Hydraulic Servo-controlled Rock Mechanics Testing System (MTS 815.04) in the University of Hong Kong, a series of permeability tests were performed on specimens of Beishan granite at different confining pressures. The result indicates that: (1) there is a decrease of permeability due to progressive closure of initial microcracks and the corresponding volumetric strain is compressive when the confining pressures increase from 2.5 MPa to 15 MPa, (2) when the confining pressures decrease from 15 MPa to 2.5 MPa, there is an increase of permeability in this stage in relation with the volumetric dilation. (authors)

Vascular permeability-increasing effect of the leaf essential oil of ...

African Journals Online (AJOL)

African Journal of Traditional, Complementary and Alternative Medicines ... Analysis of the differences in vascular permeability between treatment groups showed that, Ocimum oil, in intensity and duration, was significantly (p < 0.05) more effective in increasing cutaneous capillary permeability over a 24h period after ...

Notional Permeability

NARCIS (Netherlands)

Kik, R.; Van den Bos, J.P.; Maertens, J.; Verhagen, H.J.; Van der Meer, J.W.

2012-01-01

Different layer design of a rock slope and under layers has a large effect on the strengths on the rock slope itself. In the stability formula developed of VAN DER MEER [1988] this effect is represented by the term Notional Permeability with symbol P. A more open, or permeable, structure underneath

Clogging in permeable concrete: A review.

Science.gov (United States)

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

2017-05-15

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

Super enhanced permeability and retention (SUPR) effects in tumors following near infrared photoimmunotherapy

Science.gov (United States)

Kobayashi, Hisataka; Choyke, Peter L.

2016-06-01

To date, the delivery of nano-sized therapeutic agents to cancers largely relies on enhanced permeability and retention (EPR) effects that are caused by the leaky nature of cancer vasculature. However, nano-sized agents delivered in this way have demonstrated limited success in oncology due to the relatively small magnitude of the EPR effect. For achieving superior delivery of nano-sized agents, super-enhanced permeability and retention (SUPR) effects are needed. Near infrared photo-immunotherapy (NIR-PIT) is a recently reported therapy that treats tumors with light therapy and subsequently causes an increase in nano-drug delivery up to 24-fold compared with untreated tumors in which only the EPR effect is present. SUPR effects could enhance delivery into tumor beds of a wide variety of nano-sized agents including particles, antibodies, and protein binding small molecular agents. Therefore, taking advantage of the SUPR effects after NIR-PIT may be a promising avenue to utilize a wide variety of nano-drugs in a highly effective manner.

Effect of the aggregate grading on the concrete air permeability

Directory of Open Access Journals (Sweden)

Argiz, C.

2014-09-01

Full Text Available Great durability problems are being found in concrete structures related to the penetrability of aggressive agents through the concrete (ie. chloride penetration, sulphate attack, carbonation, freezing and thawing, and so on. Air permeability coefficient is used as an effective tool to estimate the potential durability of concrete structures due to its direct relation with the microstructure and the moisture content. This paper discusses the effect of the aggregate grading and water/cement ratio on the air permeability coefficient. An aggregate grading with more sand than coarse aggregates has resulted more beneficial from the point of view of concrete air permeability. This fact can be attributed to a denser skeleton formed by the finer aggregates. With fine aggregates, the higher water/cement ratio, the lower air permeability. However, the contrary was found with coarse aggregates. Overall, a temperature increase from 20 °C to 60 °C during preconditioning led to a Dair increase of 40–80%.Se han encontrado una gran cantidad de problemas de durabilidad de estructuras de hormigón relacionados con la penetración de agentes agresivos externos (es decir, penetración de cloruros, ataque por sulfatos, carbonatación, hielo-deshielo, etc.. El coeficiente de permeabilidad al aire se utiliza como una herramienta eficaz para estimar la durabilidad potencial de las estructuras de hormigón debido a su relación directa con su microestructura y contenido de humedad. Se discute el efecto de la gradación de los áridos y relación agua/cemento en el coeficiente de permeabilidad al aire. Con áridos más finos que gruesos, el resultado es más beneficioso, lo que se atribuye a que la arena forma un esqueleto más denso. Con áridos más finos, al aumentar la relación agua/cemento, disminuye la permeabilidad al aire; pero con áridos más gruesos se ha observado lo contrario. Cuando se pre-acondiciona de 20 °C a 60 °C, se produce un aumento del Dair

Intestinal permeability of 51Cr-labelled ethylenediaminetetraacetic acid in patients with Crohn's disease and their healthy relatives

International Nuclear Information System (INIS)

Ainsworth, M.; Eriksen, J.; Rasmussen, J.W.; Muckadell, O.B.S. de

1989-01-01

An increased intestinal permeability has been proposed as an aetiologic factor in Crohn's disease. The 24-h urinary excretion of 100 μCi 51 Cr-labelled ethylenediaminetetraacetic acid (EDTA) was used to test the permeability in 15 patients with Crohn's disease and in 20 healthy first-degree relatives, who were known to have a genetic predisposition to inflammatory bowel disease. Twenty-eight healthy persons not related to patients with inflammatory bowel disease served as control material. The 51 Cr-EDTA excretion of the relatives was not significantly higher than that of the controls, whereas patients with Crohn's disease had a significantly higher excretion than both the relatives and the controls. Among patients the increased excretion was found only if the small intestine was involved. It is concluded that 1) as a group, patient with Crohn's disease in the small intestine have an increased intestinal permeability, in contrast to their healthy relatives, who have a normal permeability; 2) a considerable overlap of the results of the 51 Cr-EDTA test was found between the groups studied, and the test is not suitable for evaluating individual patients; 3) the results do not support the hypothesis of an increase in intestinal permeability as an aetiologic factor in Crohn's disease. 29 refs

Modeling stress/strain-dependent permeability changes for deep geoenergy applications

Science.gov (United States)

Rinaldi, Antonio Pio; Rutqvist, Jonny

2016-04-01

Rock permeability is a key parameter in deep geoenergy systems. Stress and strain changes induced at depth by fluid injection or extraction may substantially alter the rock permeability in an irreversible way. With regard to the geoenergies, some applications require the permeability to be enhanced to improve productivity. The rock permeability is generally enhanced by shearing process of faults and fractures (e.g. hydroshearing for Enhanced and Deep Geothermal Systems), or the creation of new fractures (e.g. hydrofracturing for shale gas). However, such processes may, at the same time, produce seismicity that can be felt by the local population. Moreover, the increased permeability due to fault reactivation may pose at risk the sealing capacity of a storage site (e.g. carbon sequestration or nuclear waste disposal), providing then a preferential pathway for the stored fluids to escape at shallow depth. In this work we present a review of some recent applications aimed at understanding the coupling between stress (or strain) and permeability. Examples of geoenergy applications include both EGS and CO2 sequestration. To investigate both "wanted" and "unwanted" effects, THM simulations have been carried out with the TOUGH-FLAC simulator. Our studies include constitutive equations relating the permeability to mean effective stress, effective normal stress, volumetric strain, as well as accounting for permeability variation as related to fault/fracture reactivation. Results show that the geomechanical effects have a large role in changing the permeability, hence affecting fluids leakage, reservoir enhancement, as well as the induced seismicity.

Influence of effective stress and dry density on the permeability of municipal solid waste.

Science.gov (United States)

Zhang, Zhenying; Wang, Yingfeng; Xu, Hui; Fang, Yuehua; Wu, Dazhi

2018-05-01

A landfill is one of the main sites for disposal of municipal solid waste and the current landfill disposal system faces several problems. For instance, excessive leachate water is an important factor leading to landfill instability. Understanding the permeability characteristics of municipal solid waste is a relevant topic in the field of environmental geotechnical engineering. In this paper, the current research progress on permeability characteristics of municipal solid waste is discussed. A review of recent studies indicates that the research in this field is divided into two categories based on the experimental method employed: field tests and laboratory tests. This paper summarizes test methods, landfill locations, waste ages, dry densities and permeability coefficients across different studies that focus on permeability characteristics. Additionally, an experimental study on compressibility and permeability characteristics of fresh municipal solid waste under different effective stresses and compression times was carried out. Moreover, the relationships between the permeability coefficient and effective stress as well as dry density were obtained and a permeability prediction model was established. Finally, the experimental results from the existing literature and this paper were compared and the effects of effective stress and dry density on the permeability characteristics of municipal solid waste were summarized. This study provides the basis for analysis of leachate production in a landfill.

Theoretical Insight Into the Empirical Tortuosity-Connectivity Factor in the Burdine-Brooks-Corey Water Relative Permeability Model

Science.gov (United States)

Ghanbarian, Behzad; Ioannidis, Marios A.; Hunt, Allen G.

2017-12-01

A model commonly applied to the estimation of water relative permeability krw in porous media is the Burdine-Brooks-Corey model, which relies on a simplified picture of pores as a bundle of noninterconnected capillary tubes. In this model, the empirical tortuosity-connectivity factor is assumed to be a power law function of effective saturation with an exponent (μ) commonly set equal to 2 in the literature. Invoking critical path analysis and using percolation theory, we relate the tortuosity-connectivity exponent μ to the critical scaling exponent t of percolation that characterizes the power law behavior of the saturation-dependent electrical conductivity of porous media. We also discuss the cause of the nonuniversality of μ in terms of the nonuniversality of t and compare model estimations with water relative permeability from experiments. The comparison supports determining μ from the electrical conductivity scaling exponent t, but also highlights limitations of the model.

Unexpected effects of peripherally administered kynurenic acid on cortical spreading depression and related blood–brain barrier permeability

Directory of Open Access Journals (Sweden)

Oláh G

2013-09-01

Full Text Available Gáspár Oláh,1 Judit Herédi,1 Ákos Menyhárt,1 Zsolt Czinege,2 Dávid Nagy,1 János Fuzik,1 Kitti Kocsis,1 Levente Knapp,1 Erika Krucsó,1 Levente Gellért,1 Zsolt Kis,1 Tamás Farkas,1 Ferenc Fülöp,3 Árpád Párdutz,4 János Tajti,4 László Vécsei,4 József Toldi1 1Department of Physiology, Anatomy and Neuroscience, 2Department of Software Engineering, 3Institute of Pharmaceutical Chemistry and MTA-SZTE Research Group for Stereochemistry, 4Department of Neurology and MTA-SZTE Neuroscience Research Group, University of Szeged, Szeged, Hungary Abstract: Cortical spreading depression (CSD involves a slowly-propagating depolarization wave in the cortex, which can appear in numerous pathophysiological conditions, such as migraine with aura, stroke, and traumatic brain injury. Neurons and glial cells are also depolarized transiently during the phenomena. CSD is followed by a massive increase in glutamate release and by changes in the brain microcirculation. The aim of this study was to investigate the effects of two N-methyl-D-aspartate receptor antagonists, endogenous kynurenic acid (KYNA and dizocilpine, on CSD and the related blood–brain barrier (BBB permeability in rats. In intact animals, KYNA hardly crosses the BBB but has some positive features as compared with its precursor L-Kynurenine, which is frequently used in animal studies (KYNA cannot be metabolized to excitotoxic agents such as 3-hydroxy-L-kynurenine and quinolinic acid. We therefore investigated the possible effects of peripherally administered KYNA. Repetitive CSD waves were elicited by the application of 1 M KCl solution to the cortex. Direct current-electrocorticograms were measured for 1 hour. Four parameters of the waves were compared. Evans blue dye and fluorescent microscopy were used to study the possible changes in the permeability of the BBB. The results demonstrated that N-methyl-D-aspartate receptor antagonists can reduce the number of CSD waves and decrease

Suitability of Torrent Permeability Tester to measure air-permeability of covercrete

Energy Technology Data Exchange (ETDEWEB)

Andrade, C.; Gonzales-Gasca, C. [Institute of Construction Sciences ' Eduardo Torroja' , Madrid (Spain); Torrent, R. [Portland Cement Institute, (Argentina)

2000-07-01

Suitability of the Torrent Permeability Tester (TPT) to measure the permeability of covercrete to air, both in the laboratory and the field, is investigated, and test results obtained in laboratory studies are discussed. The tests performed included the determination of air permeability (TPT method), oxygen permeability (Cembureau method) and capillary suction, rapid chloride permeability test (ASTM C 1202), as well as a one-year carbonation depth test. Concrete specimens of various compositions and curing regimes were used in the tests; the gas-permeability tests were repeated on the same specimens after 28 days, than again at 6 months and 12 months. Test results confirmed the suitability of the TPT as a useful tool in the characterization of the quality the of concrete cover. It was found to be sensitive to changes in concrete quality; repeatable for sensitive properties such as gas permeability ; also, it was found to correlate well with other durability-related properties. 10 refs., 8 tabs., 8 figs.

Hydrotropic solubilization of lipophilic drugs for oral delivery: The effects of urea and nicotinamide on carbamazepine solubility-permeability interplay

Directory of Open Access Journals (Sweden)

Avital Beig

2016-10-01

Full Text Available Hydrotropy refers to increasing the water solubility of otherwise poorly soluble compound by the presence of small organic molecules. While it can certainly increase the apparent solubility of a lipophilic drug, the effect of hydrotropy on the drugs' permeation through the intestinal membrane has not been studied. The purpose of this work was to investigate the solubility-permeability interplay when using hydrotropic drug solubilization. The concentration-dependent effects of the commonly used hydrotropes urea and nicotinamide, on the solubility and the permeability of the lipophilic antiepileptic drug carbamazepine were studied. Then, the solubility-permeability interplay was mathematically modeled, and was compared to the experimental data. Both hydrotropes allowed significant concentration-dependent carbamazepine solubility increase (up to ~30-fold. A concomitant permeability decrease was evident both in-vitro and in-vivo (~17-fold for nicotinamide and ~9-fold for urea, revealing a solubility-permeability tradeoff when using hydrotropic drug solubilization. A relatively simplified simulation approach based on proportional opposite correlation between the solubility increase and the permeability decrease at a given hydrotrope concentration allowed excellent prediction of the overall solubility-permeability tradeoff. In conclusion, when using hydrotropic drug solubilization it is prudent to not focus solely on solubility, but to account for the permeability as well; achieving optimal solubility-permeability balance may promote the overall goal of the formulation to maximize oral drug exposure.

Hydrotropic Solubilization of Lipophilic Drugs for Oral Delivery: The Effects of Urea and Nicotinamide on Carbamazepine Solubility–Permeability Interplay

Science.gov (United States)

Beig, Avital; Lindley, David; Miller, Jonathan M.; Agbaria, Riad; Dahan, Arik

2016-01-01

Hydrotropy refers to increasing the water solubility of otherwise poorly soluble compound by the presence of small organic molecules. While it can certainly increase the apparent solubility of a lipophilic drug, the effect of hydrotropy on the drugs’ permeation through the intestinal membrane has not been studied. The purpose of this work was to investigate the solubility–permeability interplay when using hydrotropic drug solubilization. The concentration-dependent effects of the commonly used hydrotropes urea and nicotinamide, on the solubility and the permeability of the lipophilic antiepileptic drug carbamazepine were studied. Then, the solubility–permeability interplay was mathematically modeled, and was compared to the experimental data. Both hydrotropes allowed significant concentration-dependent carbamazepine solubility increase (up to ∼30-fold). A concomitant permeability decrease was evident both in vitro and in vivo (∼17-fold for nicotinamide and ∼9-fold for urea), revealing a solubility–permeability tradeoff when using hydrotropic drug solubilization. A relatively simplified simulation approach based on proportional opposite correlation between the solubility increase and the permeability decrease at a given hydrotrope concentration allowed excellent prediction of the overall solubility–permeability tradeoff. In conclusion, when using hydrotropic drug solubilization it is prudent to not focus solely on solubility, but to account for the permeability as well; achieving optimal solubility–permeability balance may promote the overall goal of the formulation to maximize oral drug exposure. PMID:27826241

Permeability-Porosity Relationships of Subduction Zone Sediments

Science.gov (United States)

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

2008-12-01

Permeability-porosity relationships for sediments from Northern Barbados, Costa Rica, Nankai, and Peru subduction zones were examined based on their sediment type and grain size distribution. Greater correlation was observed between permeability and porosity for siliciclastic sediments, diatom oozes, and nannofossil chalk than for nannofossil oozes. For siliciclastic sediments, grouping of sediments by clay content yields relationships that are generally consistent with results from other marine settings and suggest decreasing permeability for a given porosity as clay content increases. Correction of measured porosities for smectite content generally improves the quality of permeability-porosity relationships. The relationship between permeability and porosity for diatom oozes may be controlled by the amount of clay present in the ooze, causing diatom oozes to behave similarly to siliciclastic sediments. For a given porosity the nannofossil oozes have higher permeability values by 1.5 orders of magnitude than the siliciclastic sediments. However, the use of a permeability-porosity relation may not be appropriate for unconsolidated carbonates such as nannofossil oozes. This study provided insight to the effects of porosity correction for smectite, variations in lithology and grain size in permeability-porosity relationships. However, further progress in delineating controls on permeability will require more careful and better documented permeability tests on characterized samples.

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

Science.gov (United States)

Singh, R.; Olson, M. S.

2011-12-01

to decrease at 9.8 mm and 19.6 mm cross-sections in low permeability regions due to dilution with the injectate from the non-porous channel (Figure 1). However, relative bacterial counts increased in the low permeability region at both downstream cross-sections under chemotactic conditions. A large increase in relative bacterial count in the pore throats just outside the low permeability region was also observed at both cross-sections (Figure 1). The bacterial chemotactic response was observed to decrease linearly with increasing Darcy velocity and at flow rate 0.220 mm/s the chemotactic effect was offset by the advective flow in the porous channel.

Radiation Effects on the Cytoskeleton of Endothelial Cells and Endothelial Monolayer Permeability

International Nuclear Information System (INIS)

Gabrys, Dorota; Greco, Olga; Patel, Gaurang; Prise, Kevin M.; Tozer, Gillian M.; Kanthou, Chryso

2007-01-01

Purpose: To investigate the effects of radiation on the endothelial cytoskeleton and endothelial monolayer permeability and to evaluate associated signaling pathways, which could reveal potential mechanisms of known vascular effects of radiation. Methods and Materials: Cultured endothelial cells were X-ray irradiated, and actin filaments, microtubules, intermediate filaments, and vascular endothelial (VE)-cadherin junctions were examined by immunofluorescence. Permeability was determined by the passage of fluorescent dextran through cell monolayers. Signal transduction pathways were analyzed using RhoA, Rho kinase, and stress-activated protein kinase-p38 (SAPK2/p38) inhibitors by guanosine triphosphate-RhoA activation assay and transfection with RhoAT19N. The levels of junction protein expression and phosphorylation of myosin light chain and SAPK2/p38 were assessed by Western blotting. The radiation effects on cell death were verified by clonogenic assays. Results: Radiation induced rapid and persistent actin stress fiber formation and redistribution of VE-cadherin junctions in microvascular, but not umbilical vein endothelial cells, and microtubules and intermediate filaments remained unaffected. Radiation also caused a rapid and persistent increase in microvascular permeability. RhoA-guanosine triphosphatase and Rho kinase were activated by radiation and caused phosphorylation of downstream myosin light chain and the observed cytoskeletal and permeability changes. SAPK2/p38 was activated by radiation but did not influence either the cytoskeleton or permeability. Conclusion: This study is the first to show rapid activation of the RhoA/Rho kinase by radiation in endothelial cells and has demonstrated a link between this pathway and cytoskeletal remodeling and permeability. The results also suggest that the RhoA pathway might be a useful target for modulating the permeability and other effects of radiation for therapeutic gain

Thermoporoelastic effects during heat extraction from low-permeability reservoirs

DEFF Research Database (Denmark)

Salimzadeh, Saeed; Nick, Hamidreza M.; Zimmerman, R. W.

2018-01-01

Thermoporoelastic effects during heat extraction from low permeability geothermal reservoirs are investigated numerically, based on the model of a horizontal penny-shaped fracture intersected by an injection well and a production well. A coupled formulation for thermo-hydraulic (TH) processes...... in EGS projects. Therefore, using the undrained thermal expansion coefficient for the matrix may overestimate the volumetric strain of the rock in low-permeability enhanced geothermal systems, whereas using a drained thermal expansion coefficient for the matrix may underestimate the volumetric strain...

Biofilm Effect on Flow Structure over a Permeable Bed

Science.gov (United States)

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

2017-12-01

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

Estimation of non-linear effective permeability of magnetic materials with fine structure

International Nuclear Information System (INIS)

Waki, H.; Igarashi, H.; Honma, T.

2006-01-01

This paper describes a homogenization method for magnetic materials with fine structure. In this method, the structures of the magnetic materials are assumed to be periodic, and the unit cell is defined. The effective permeability is determined on the basis of magnetic energy balance in the unit cell. This method can be applied not only for linear problems but also for non-linear ones. In this paper, estimation of the effective permeability of non-linear magnetic materials by using the homogenization method is described in detail, and then the validity for the non-liner problems is tested for two-dimensional problems. It is shown that this homogenization method gives accurate non-linear effective permeability

Effect of CH4 on the CO2 breakthrough pressure and permeability of partially saturated low-permeability sandstone in the Ordos Basin, China

Science.gov (United States)

Zhao, Yan; Yu, Qingchun

2018-01-01

The behavior of CO2 that coexists with CH4 and the effect of CH4 on the CO2 stream need to be deeply analyzed and studied, especially in the presence of water. Our previous studies investigated the breakthrough pressure and permeability of pure CO2 in five partially saturated low-permeability sandstone core samples from the Ordos Basin, and we concluded that rocks with a small pore size and low permeability show considerable sealing capacity even under unsaturated conditions. In this paper, we selected three of these samples for CO2-CH4 gas-mixture breakthrough experiments under various degrees of water saturation. The breakthrough experiments were performed by increasing the gas pressure step by step until breakthrough occurred. Then, the effluent gas mixture was collected for chromatographic partitioning analysis. The results indicate that CH4 significantly affects the breakthrough pressure and permeability of CO2. The presence of CH4 in the gas mixture increases the interfacial tension and, thus, the breakthrough pressure. Therefore, the injected gas mixture that contains the highest (lowest) mole fraction of CH4 results in the largest (smallest) breakthrough pressure. The permeability of the gas mixture is greater than that for pure CO2 because of CH4, and the effective permeability decreases with increased breakthrough pressure. Chromatographic partitioning of the effluent mixture gases indicates that CH4 breaks through ahead of CO2 as a result of its weaker solubility in water. Correlations are established between (1) the breakthrough pressure and water saturation, (2) the effective permeability and water saturation, (3) the breakthrough pressure and effective permeability, and (4) the mole fraction of CO2/CH4 in the effluent mixture gases and water saturation. These results deepen our understanding of the multi-phase flow behavior in the porous media under unsaturated conditions, which have implications for formulating emergency response plans for gas

Assessment of porous material anisotropy and its effect on gas permeability

Science.gov (United States)

Wałowski, Grzegorz

2017-10-01

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

Effect of preparation conditions on properties and permeability of chitosan-sodium hexametaphosphate capsules.

Science.gov (United States)

Angelova, N; Hunkeler, D

2001-01-01

Capsules were obtained by interpolymer complexation between chitosan (polycation) and sodium hexametaphosphate (SMP, oligoanion). The effect of the preparation conditions on the capsule characteristics was evaluated. Specifically, the influence of variables such as pH, ionic strength, reagent concentration, and additives on the capsule permeability properties was investigated using dextran as a model permeant. The capsule membrane permeability was found to increase by decreasing the chitosan/SMP ratio as well as adding mannitol to the oligoanion recipient bath. Increasing the ionic strength or the pH of the initial chitosan solution was also found to enhance the membrane permeability, moving the membrane exclusion limit to higher values. Generally, the capsules prepared tinder all tested conditions had a relatively low permeability which rarely exceeded a molecular cut-off of 40 kD based on dextran standards. Furthermore, the diffusion rate showed a strong temporal dependence, indicating that the capsules prepared under various conditions exhibit different apparent pore size densities on the surface. The results indicated that, in order to obtain the desired capsule mass-transfer properties, the preparation conditions should be carefully considered and adjusted. Adding a polyol as well as low salt amount (less than 0.15%) is preferable as a means of modulating the diffusion characteristics, without disturbing the capsule mechanical stability.

Effects of a Dicalcium and Tetracalcium Phosphate-Based Desensitizer on In Vitro Dentin Permeability.

Directory of Open Access Journals (Sweden)

Jianfeng Zhou

Full Text Available The present study evaluated the effectiveness of a dicalcium and tetracalcium phosphate-based desensitizer in reducing dentin permeability in vitro. Dentin fluid flow was measured before and after treatment of dentin with patent dentinal tubules using 1 or 3 applications of the dicalcium and tetracalcium phosphate containing agent TeethmateTM (TM and comparing the results with two sodium fluoride varnishes VellaTM (VLA and VanishTM (VAN, after storage in artificial saliva for 24 h, 48 h and 7 days. Significant differences were observed among the 4 methods employed for reducing dentin permeability (p < 0.001 and the 3 post-treatment times (p < 0.001. VLA and VAN never achieved 50% permeability reductions consistently in any of the 3 time periods. Only the calcium phosphate-based desensitizer applied for 3 times consistently reduced dentin permeability by 50% after 24 h. When applied once, the permeability reduction of TM increased progressively over the 3 time periods. After 7 days, only one and three applications of the calcium phosphate-based desensitizer consistently reduced dentin permeability by more than 50%. Permeability reductions corresponded well with scanning electron microscopy examination of dentinal tubule orifice occlusion in dentin specimens treated with the agents. Overall, the dicalcium and tetracalcium phosphate-based desensitizer is effective in reducing dentin permeability via a tubule occlusion mechanism. The ability of the agent to reduce dentin permeability renders it to be potentially useful as a clinical dentin desensitizing agent, which has to be confirmed in future clinical studies. By contrast, the two sodium fluoride varnishes are not effective in dentin permeability reduction and should be considered as topical fluoride delivering agents rather than tubular orifice-blocking agents.

Effect of 5-aminosalicylic acid on myocardial capillary permeability following ischaemia and reperfusion

DEFF Research Database (Denmark)

Hansen, P R; Svendsen, Jesper Hastrup; Høst, N B

1992-01-01

The aim was to evaluate the effect of 5-aminosalicylic acid on myocardial capillary permeability for small hydrophilic molecules after ischaemia and reperfusion.......The aim was to evaluate the effect of 5-aminosalicylic acid on myocardial capillary permeability for small hydrophilic molecules after ischaemia and reperfusion....

Meteoric calcite cementation: diagenetic response to relative fall in sea-level and effect on porosity and permeability, Las Negras area, southeastern Spain

Science.gov (United States)

Li, Zhaoqi; Goldstein, Robert H.; Franseen, Evan K.

2017-03-01

A dolomitized Upper Miocene carbonate system in southeast Spain contains extensive upper and lower zones of calcite cementation that cut across the stratigraphy. Cement textures including isopachous and circumgranular, which are consistent with phreatic-zone cementation. Cements in the upper cemented zone are non-luminescent, whereas those in the lower cemented zone exhibit multiple bands of luminescent and non-luminescent cements. In the upper cemented zone, isotopic data show two meteoric calcite lines (MCL) with mean δ18O at - 5.1‰ and - 5.8‰ VPDB, whereas no clear MCL is defined in the lower cemented zone where mean δ18O for calcite cement is at - 6.7‰ VPDB. δ13C values in both cement zones are predominantly negative, ranging from - 10 to + 2‰ VPDB, suggestive of carbon from soil gas or decayed organics. Measurements of Tm ice in primary fluid inclusions yield a mode of 0.0 °C in both zones, indicating calcite cementation from fresh water. These two zones define the positions of two different paleo-water tables that formed during a relative sea-level fall and erosional downcutting during the Plio-Pleistocene. The upper cemented zone pre-dated the lower cemented zone on the basis of known relative sea-level history. Meteoric calcite cementation reduced porosity and permeability, but measured values are inconsistent with simple filling of open pore space. Each texture, boundstone, grainstone, packstone, wackestone, produces a different relationship between percent calcite cement and porosity/permeability. Distribution of cements may be predictable on the basis of known sea-level history, and the effect of the cementation can be incorporated into subsurface geomodels by defining surfaces of rock boundaries that separate cemented zones from uncemented zones, and applying texture-specific relationships among cementation, porosity and permeability.

Measurement of choroid plexus perfusion using dynamic susceptibility MR imaging: capillary permeability and age-related changes

Energy Technology Data Exchange (ETDEWEB)

Bouzerar, Roger; Chaarani, Bader; Baledent, Olivier [University Hospital, Image Processing Department, Amiens (France); Gondry-Jouet, Catherine [University Hospital, Radiology Department, Amiens (France); Zmudka, Jadwiga [University Hospital, Geriatric Unit, Amiens (France)

2013-12-15

The cerebrospinal fluid (CSF) plays a major role in the physiology of the central nervous system. The continuous turnover of CSF is mainly attributed to the highly vascularized choroid plexus (CP) located in the cerebral ventricles which represent a complex interface between blood and CSF. We propose a method for evaluating CP functionality in vivo using perfusion MR imaging and establish the age-related changes of associated parameters. Fifteen patients with small intracranial tumors were retrospectively studied. MR Imaging was performed on a 3T MR Scanner. Gradient-echo echo planar images were acquired after bolus injection of gadolinium-based contrast agent (CA). The software developed used the combined T1- and T2-effects. The decomposition of the relaxivity signals enables the calculation of the CP capillary permeability (K{sub 2}). The relative cerebral blood volume (rCBV), mean transit time (MTT), and signal slope decrease (SSD) were also calculated. The mean permeability K{sub 2} of the extracted CP was 0.033+/-0.18 s{sup -1}. K{sub 2} and SSD significantly decreased with subject's age whereas MTT significantly increased with subject's age. No significant correlation was found for age-related changes in rCBV and rCBF. The decrease in CP permeability is in line with the age-related changes in CSF secretion observed in animals. The MTT increase indicates significant structural changes corroborated by microscopy studies in animals or humans. Overall, DSC MR-perfusion enables an in vivo evaluation of the hemodynamic state of CP. Clinical applications such as neurodegenerative diseases could be considered thanks to specific functional studies of CP. (orig.)

Permeability of skin and oral mucosa to water and horseradish peroxidase as related to the thickness of the permeability barrier

International Nuclear Information System (INIS)

Squier, C.A.; Hall, B.K.

1985-01-01

The permeability of porcine skin and keratinized and nonkeratinized oral mucosa to tritium-labeled water and horseradish peroxidase (HRPO) was determined using perfusion chambers. Small blocks from each tissue were also incubated with HRPO and the extent of penetration visualized microscopically; this enabled measurements to be made of the thickness of the permeability barrier to this water-soluble tracer. Results obtained after inverting the oral mucosa in the chambers or adding metabolic inhibitors indicated that both compounds diffuse across the tissue. The permeability constants derived directly in the study showed that skin was less permeable than oral mucosa and that the floor of the mouth was significantly more permeable than all other regions. When these constants were normalized in terms of a standard permeability barrier thickness and the different tissues compared, the values obtained for skin were again less than those of the oral regions but, of these, the buccal mucosa was significantly higher. The difference in permeability between epidermis and keratinized oral epithelium may be due to differences in the volume density of membrane-coating granules known to exist between the tissues; differences between the oral mucosal regions may reflect differences in the nature of the intercellular barrier material

The effect of meniscus on the permeability of micro-post arrays

International Nuclear Information System (INIS)

Byon, Chan; Kim, Sung Jin

2011-01-01

This study aims to investigate the effect of meniscus curvature on the permeability of the micro-post arrays, which are widely used for applications of microfluidics. An analytical model that accounts for the meniscus curvature is developed. The model considers two common array types: quadratic and hexagonal arrays. The permeability of micro-post arrays is estimated using the capillary rate of rise experiment and numerical simulation. The results obtained from the analytical model match the experimental and numerical results within the error of 5% over the range of parameters commonly found in microfluidic applications (0.06 0.2), where d * and H * are the post-diameter and the post-height, respectively, which are normalized by the pitch. Based on the analytic results, the effects of the post-diameter, post-height and the contact angle on the permeability of post-arrays are investigated. It is shown that the previous permeability models based on the flat meniscus assumption overestimate the experimental value by 26% for the quadratic array and 24% for the hexagonal array when cos θ = 1, d * = 0.5 and H *=1. The effect of the meniscus curvature is shown to become more pronounced as the contact angle or the post-height decreases.

Active intestinal drug absorption and the solubility-permeability interplay.

Science.gov (United States)

Porat, Daniel; Dahan, Arik

2018-02-15

The solubility-permeability interplay deals with the question: what is the concomitant effect on the drug's apparent permeability when increasing the apparent solubility with a solubility-enabling formulation? The solubility and the permeability are closely related, exhibit certain interplay between them, and ongoing research throughout the past decade shows that treating the one irrespectively of the other may be insufficient. The aim of this article is to provide an overview of the current knowledge on the solubility-permeability interplay when using solubility-enabling formulations for oral lipophilic drugs, highlighting active permeability aspects. A solubility-enabling formulation may affect the permeability in opposite directions; the passive permeability may decrease as a result of the apparent solubility increase, according to the solubility-permeability tradeoff, but at the same time, certain components of the formulation may inhibit/saturate efflux transporters (when relevant), resulting in significant apparent permeability increase. In these cases, excipients with both solubilizing and e.g. P-gp inhibitory properties may lead to concomitant increase of both the solubility and the permeability. Intelligent development of such formulation will account for the simultaneous effects of the excipients' nature/concentrations on the two arms composing the overall permeability: the passive and the active arms. Overall, thorough mechanistic understanding of the various factors involved in the solubility-permeability interplay may allow developing better solubility-enabling formulations, thereby exploiting the advantages analyzed in this article, offering oral delivery solution even for BCS class IV drugs. Copyright © 2017 Elsevier B.V. All rights reserved.

Systematic Analysis of the Effect of Small Scale Permeability Heterogeneity on Hyporheic Exchange Flux and Residence Times

Science.gov (United States)

Laube, G.; Schmidt, C.; Fleckenstein, J. H.

2014-12-01

The hyporheic zone (HZ) contributes significantly to whole stream biogeochemical cycling. Biogeochemical reactions within the HZ are often transport limited, thus, understanding these reactions requires knowledge about the magnitude of hyporheic fluxes (HF) and the residence time (RT) of these fluxes within the HZ. While the hydraulics of HF are relatively well understood, studies addressing the influence of permeability heterogeneity lack systematic analysis and have even produced contradictory results (e.g. [1] vs. [2]). In order to close this gap, this study uses a statistical numerical approach to elucidate the influence of permeability heterogeneity on HF and RT. We simulated and evaluated 3750 2D-scenarios of sediment heterogeneity by means of Gaussian random fields with focus on total HF and RT distribution. The scenarios were based on ten realizations of each of all possible combinations of 15 different correlation lengths, 5 dipping angles and 5 permeability variances. Roughly 500 hyporheic stream traces were analyzed per simulation, for a total of almost two million stream traces analyzed for correlations between permeability heterogeneity, HF, and RT. Total HF and the RT variance positively correlated with permeability variance while the mean RT negatively correlated with permeability variance. In contrast, changes in correlation lengths and dipping angles had little effect on the examined properties RT and HF. These results provide a possible explanation of the seemingly contradictory conclusions of recent studies, given that the permeability variances in these studies differ by several orders of magnitude. [1] Bardini, L., Boano, F., Cardenas, M.B, Sawyer, A.H, Revelli, R. and Ridolfi, L. "Small-Scale Permeability Heterogeneity Has Negligible Effects on Nutrient Cycling in Streambeds." Geophysical Research Letters, 2013. doi:10.1002/grl.50224. [2] Zhou, Y., Ritzi, R. W., Soltanian, M. R. and Dominic, D. F. "The Influence of Streambed Heterogeneity on

3D numerical surface charge model including relative permeability : the general theory

NARCIS (Netherlands)

Casteren, van D.T.E.H.; Paulides, J.J.H.; Lomonova, E.A.

2014-01-01

One of the still "open" issues within low-frequency magnetics is the inclusion of µr in the calculations using the magnetic charge method. In this paper a new iterative method to take the relative permeability into account is investigated. Results show that the model accurately accounts for the

Effect of platelet activating factor on endothelial permeability to plasma macromolecules

International Nuclear Information System (INIS)

Handley, D.A.; Arbeeny, C.M.; Lee, M.L.; Van Valen, R.G.; Saunders, R.N.

1984-01-01

The effect of intrajugular administration of platelet activating factor (PAF-C16) on vascular permeability was examined in the guinea pig. To examine the loss of selective endothelial permeability, the extravasative effect of PAF was assessed by monitoring hemoconcentration and the plasma loss of 125 I-albumin (6.7 nm), 125 I-low density lipoproteins (22.0 nm) or 125 I-very low density lipoproteins (62.1 nm). Extravasation was dose-dependent and began 1 min after PAF administration, continuing for 5-7 min. During extravasation, there was no evidence for selective plasma retention of any of the labeled plasma tracers, as measured by plasma radioactivity. These results suggest that PAF-induced extravasation is dose-dependent, with increases in vascular permeability sufficient to permit similar plasma efflux rates of albumin, low density lipoproteins and very low density lipoproteins

Compact rock material gas permeability properties

Energy Technology Data Exchange (ETDEWEB)

Wang, Huanling, E-mail: whl_hm@163.com [Key Laboratory of Coastal Disaster and Defence, Ministry of Education, Hohai University, Nanjing 210098 (China); LML, University of Lille, Cite Scientifique, 59655 Villeneuve d’Ascq (France); Xu, Weiya; Zuo, Jing [Institutes of Geotechnical Engineering, Hohai University, Nanjing 210098 (China)

2014-09-15

Natural compact rocks, such as sandstone, granite, and rock salt, are the main materials and geological environment for storing underground oil, gas, CO{sub 2,} 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{sup −19} m{sup 2}; for the granite gneiss (B-2), the initial porosity is approximately 7.09%, the permeability is approximately 10{sup −17} m{sup 2}; 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.

Permeability of hydrogen isotopes through Pd-Ag membrane

International Nuclear Information System (INIS)

Yoshida, Hiroshi

1981-01-01

This paper represents the permeabilities, diffusion coefficients and isotope effects for hydrogen and deuterium through Pd-25 wt.% Ag alloy tubes The feed gas H 2 or D 2 flowing into the permeation cell was preheated before it reached to the outer surface of the permeation tube made of palladium-silver alloy. Permeation time lag method could be successfully carried out with the present apparatus to measure both permeability and diffusion coefficient. The square-root pressure dependence for the permeation of hydrogen isotopes was observed. The observed systematic temperature dependence indicates that the approximation of the Arrhenius' relation was effective within this experimental conditions. Some tendency of permeation fluxes in relation to the reciprocal temperature, 1/T, was seen. The permeability ratio was larger than the square root of isotopic mass ratio, and it decreased with temperature rise. On the contrary, the diffusion coefficient ratio was much smaller than the square root of isotopic mass ratio. (Kato, T.)

Experimental study of the permeability of concrete under variable thermal and hydric conditions

International Nuclear Information System (INIS)

Chen, W.

2011-01-01

The main objective of this study is to evaluate the variable thermal and hydric effect, with fissuration effect on the hydraulic behaviour of two concretes. Many experimental tests (saturation and permeability measurements, uniaxial and triaxial compressions tests) were carried out in order to investigate the temperature and saturation influence on the behaviour hydraulic on sound and micro-cracked concrete. Moreover, an experimental device for permeability measurement on macro-cracked concrete was realized, it allows to study the behaviour of macro-cracked of concrete confined and subjected to dry gas flow or very moist air at different temperatures. Multiaxial mechanical tests are coupled to the permeability measurements of sound concrete and micro-cracked by freezing and thawing, which allow to measuring the permeability under deviatoric load-unload with the effect of pre-cracking under stress. We also effectuated a test of relative permeability of concrete as a function of water saturation, subjected to drying and re-saturation, conditioning by the different relative humidity imposed. (author)

The effects of hypoglycemic and alcoholic coma on the blood-brain barrier permeability

Science.gov (United States)

Yorulmaz, Hatice; Seker, Fatma Burcu; Oztas, Baria

2011-01-01

In this investigation, the effects of hypoglycemic coma and alcoholic coma on the blood-brain barrier (BBB) permeability have been compared. Female adult Wistar albino rats weighing 180-230 g were divided into three groups: Control group (n=8), Alcoholic Coma Group (n=18), and Hypoglycemic Coma group (n=12). The animals went into coma approximately 3-4 hours after insulin administration and 3-5 minutes after alcohol administration. Evans blue (4mL/kg) was injected intravenously as BBB tracer. It was observed that the alcoholic coma did not significantly increase the BBB permeability in any of the brain regions when compared to control group. Changes in BBB permeability were significantly increased by the hypoglycemic coma in comparison to the control group values (pcoma have different effects on the BBB permeability depending on the energy metabolism. PMID:21619558

Intestinal Permeability: The Basics

Directory of Open Access Journals (Sweden)

Ingvar Bjarnason

1995-01-01

Full Text Available The authors review some of the more fundamental principles underlying the noninvasive assessment of intestinal permeability in humans, the choice of test markers and their analyses, and the practical aspects of test dose composition and how these can be changed to allow the specific assessment of regional permeability changes and other intestinal functions. The implications of increased intestinal permeability in the pathogenesis of human disease is discussed in relation to findings in patients with Crohn’s disease. A common feature of increased intestinal permeability is the development of a low grade enteropathy, and while quantitatively similar changes may be found in Crohn’s disease these seem to predict relapse of disease. Moreover, factors associated with relapse of Crohn’s disease have in common an action to increase intestinal permeability. While increased intestinal permeability does not seem to be important in the etiology of Crohn’s disease it may be a central mechanism in the clinical relapse of disease.

Characterization and estimation of permeability correlation structure from performance data

Energy Technology Data Exchange (ETDEWEB)

Ershaghi, I.; Al-Qahtani, M. [Univ. of Southern California, Los Angeles, CA (United States)

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.

Negative permeability from random particle composites

Energy Technology Data Exchange (ETDEWEB)

Hussain, Shahid, E-mail: shussain2@qinetiq.com

2017-04-15

Artificial media, such as those composed of periodically-spaced wires for negative permittivity and split ring resonators for negative permeability have been extensively investigated for negative refractive index (NRI) applications (Smith et al., 2004; Pendry et al., 1999) [1,2]. This paper presents an alternative method for producing negative permeability: granular (or particulate) composites incorporating magnetic fillers. Artificial media, such as split-ring resonators, are designed to produce a magnetic resonance feature, which results in negative permeability over a narrow frequency range about the resonance frequency. The position of the feature is dependent upon the size of the inclusion. The material in this case is anisotropic, such that the feature is only observable when the materials are orientated in a specific direction relative to the applied field. A similar resonance can be generated in magnetic granular (particulate) materials: ferromagnetic resonance from the natural spin resonance of particles. Although the theoretical resonance profiles in granular composites shows the permeability dipping to negative values, this is rarely observed experimentally due to resonance damping effects. Results are presented for iron in spherical form and in flake form, dispersed in insulating host matrices. The two particle shapes show different permeability performance, with the magnetic flakes producing a negative contribution. This is attributed to the stronger coupling with the magnetic field resulting from the high aspect ratio of the flakes. The accompanying ferromagnetic resonance is strong enough to overcome the effects of damping and produce negative permeability. The size of random particle composites is not dictated by the wavelength of the applied field, so the materials are potentially much thinner than other, more traditional artificial composites at microwave frequencies. - Highlights: • Negative permeability from random particle composites is

Effect of aggregate grain size distribution on properties of permeable ...

African Journals Online (AJOL)

) ratio on the mechanical properties of permeable concrete is investigated. The aim of this study is to prepare permeable concrete mixture with optimum properties in terms of strength and permeability. For this purpose, five different permeable ...

Effect of injection water quality on permeability of productive sands in Shaimsk group of oil fields

Energy Technology Data Exchange (ETDEWEB)

Andreeva, N I; Ivanov, V N; Lazarev, V N; Maksimov, V P

1966-01-01

Water from the Kond River is used to flood Shaimsk oil fields. Effect of raw and filtered waters on permeability of Shaimsk cores was experimentally determined. The raw river water contained 26 mg/liter of suspended solids, 10.7 mg/liter of total iron, 4.3 mg/liter of suspended iron oxide, and a pH of 6.4. The filtered river water was free of suspended solids and had a pH of 6.2. It was found that both raw and filtered water decreased core permeability. The unfiltered water decreased permeability 2 to 7 times more than the filtered water. Also, the decrease in permeability occurs much more slowly with the filtered than the unfiltered water. The effect of water on core permeability is essentially irreversible. Efforts to restore core permeability by reversing flow direction were not successful. Among the reasons for the permeability decrease were hydration and swelling of clays and evolution of gases from water in the cores. (10 refs.)

Effect of desensitizing agents on dentin permeability.

Science.gov (United States)

Ishihata, Hiroshi; Kanehira, Masafumi; Nagai, Tomoko; Finger, Werner J; Shimauchi, Hidetoshi; Komatsu, Masashi

2009-06-01

To investigate the in vitro efficacy of two dentin desensitizing products at reducing liquid permeability through human dentin discs. The tested hypothesis was that the products, in spite of different chemical mechanisms were not different at reducing or eliminating flow through dentin discs. Dentin slices (1 mm thick) were prepared from 16 extracted human third molars and their permeability was indirectly recorded in a split chamber model, using a chemiluminescence technique, after EDTA treatment (control), after soaking with albumin, and after desensitizer application. Two products were studied: MS Coat, a self-curing resin-containing oxalate product, and Gluma Desensitizer, a glutaraldehyde/HEMA-based agent without initiator. The dentin slices were mounted between an upper chamber, filled with an aqueous solution of 1% potassium ferricyanide and 0.3% hydrogen peroxide, and a lower chamber filled with 1% sodium hydroxide solution and 0.02% luminol. The upper solution was pressurized, and upon contact with the luminol solution a photochemical signal was generated and recorded as a measure of permeability throughout two consecutive pressurizing cycles at 2.5 and 13 kPa (26 and 133 cm H2O), respectively. The permeability of the control and albumin-soaked samples was similarly high. After application of the desensitizing agents, dentin permeability was reduced to virtually zero at both pressure levels (P < 0.001).

Hydrothermal alteration and permeability changes in granitic intrusions related to Sn-W deposits : case study of Panasqueira (Portugal)

Science.gov (United States)

Launay, Gaetan; Sizaret, Stanislas; Guillou-Frottier, Laurent; Gloaguen, Eric; Melleton, Jérémie; Pichavant, Michel; Champallier, Rémi; Pinto, Filipe

2017-04-01

The Panasqueira Sn-W deposit occurs as a dense network of flat wolframite and cassiterite-bearing quartz veins concentrated in the vicinity of a hidden greisen cupola, and to a lesser extent as disseminated cassiterites in the greisen. Previous studies (Thadeu 1951; 1979) have suggested that the Panasqueira deposit is genetically related to magmatic activity for which the most part is unexposed, and being only represented by the greisen cupola. Hydrothermal fluid circulation during the final stages of granite crystallisation has probably led to the greisenisation of the cupola followed by the deposition of the mineralization in the veins system. Mineral replacement reactions that occurred during the greisenisation could affect rock properties (porosity, density and permeability) which control fluid circulation in the granite. This study aims to investigate effects of greisenisation reactions on the dynamic (time varying) permeability that ultimately leads to fluid circulation in the greisen cupola. To do so, petrological study and experimental determinations of hydrodynamic features (porosity and permeability) for different granite alteration levels and petrographic types (unaltered granite to greisen) are combined and then integrated in coupled numerical models of fluid circulation around the granitic intrusion. Greisen occurs in the apical part of the granitic body and results in the pervasive alteration of the granite along the granite-schist contact. This greisen consists mainly of quartz and muscovite formed by the replacement of feldspars and bleaching of biotites of the initial granite. Otherwise, greisen is generally vuggy which suggests a porosity increase of the granite during hydrothermal alteration processes. This porosity increase has a positive effect on the permeability of the granitic system. Indeed, experimental measurements of permeability with the Paterson press indicate that the initial granite is impermeable (10-20 m2) whereas the greisen is

Diagenetic effect on permeabilities of geothermal sandstone reservoirs

DEFF Research Database (Denmark)

Weibel, Rikke; Olivarius, Mette; Kristensen, Lars

The Danish subsurface contains abundant sedimentary deposits, which can be utilized for geothermal heating. The Upper Triassic – Lower Jurassic continental-marine sandstones of the Gassum Formation has been utilised as a geothermal reservoir for the Thisted Geothermal Plant since 1984 extracting...... and permeability is caused by increased diagenetic changes of the sandstones due to increased burial depth and temperatures. Therefore, the highest water temperatures typically correspond with the lowest porosities and permeabilities. Especially the permeability is crucial for the performance of the geothermal......-line fractures. Continuous thin chlorite coatings results in less porosity- and permeability-reduction with burial than the general reduction with burial, unless carbonate cemented. Therefore, localities of sandstones characterized by these continuous chlorite coatings may represent fine geothermal reservoirs...

Study on road surface source pollution controlled by permeable pavement

Science.gov (United States)

Zheng, Chaocheng

2018-06-01

The increase of impermeable pavement in urban construction not only increases the runoff of the pavement, but also produces a large number of Non-Point Source Pollution. In the process of controlling road surface runoff by permeable pavement, a large number of particulate matter will be withheld when rainwater is being infiltrated, so as to control the source pollution at the source. In this experiment, we determined the effect of permeable road surface to remove heavy pollutants in the laboratory and discussed the related factors that affect the non-point pollution of permeable pavement, so as to provide a theoretical basis for the application of permeable pavement.

Controlling DC permeability in cast steels

Energy Technology Data Exchange (ETDEWEB)

Sumner, Aaran, E-mail: aaran.sumner@nottingham.ac.uk [University of Nottingham, Nottingham University Park Campus, Nottingham NG7 2RD, England (United Kingdom); Gerada, Chris, E-mail: chris.gerada@nottingham.ac.uk [Electrical Machines, University of Nottingham, Tower Building, Nottingham NG7 2RD, England (United Kingdom); Brown, Neil, E-mail: neil.brown@cummins.com [Advanced Electrical Machines Research and Technology at Cummins Power Generation, Peterborough PE2 6FZ, England (United Kingdom); Clare, Adam, E-mail: adam.clare@nottingham.ac.uk [Advanced Manufacturing, University of Nottingham, University Park Campus, Nottingham NG7 2RD, England (United Kingdom)

2017-05-01

Annealing (at multiple cooling rates) and quenching (with tempering) was performed on specimens of cast steel of varying composition. The aim was to devise a method for selecting the steel with the highest permeability, from any given range of steels, and then increasing the permeability by heat treatment. Metallographic samples were imaged using optical microscopy to show the effect of the applied heat treatments on the microstructure. Commonly cast steels can have DC permeability altered by the careful selection of a heat treatment. Increases of up to 381% were achieved by annealing using a cooling rate of 6.0 °C/min. Annealing was found to cause the carbon present in the steel to migrate from grain boundaries and from within ferrite crystals into adjacent pearlite crystals. The migration of the carbon resulted in less carbon at grain boundaries and within ferrite crystals reducing the number of pinning sites between magnetic domains. This gives rise to a higher permeability. Quenching then tempering was found to cause the formation of small ferrite crystals with the carbon content of the steel predominately held in the martensitic crystal structures. The results show that with any given range of steel compositions the highest baseline DC permeability will be found with the steel that has the highest iron content and the lowest carbon content. For the samples tested in this paper a cooling rate of 4.5 °C/min resulted in the relative permeability of the sample with the highest baseline permeability, AS4, increasing from 783 to 1479 at 0.5 T. This paper shows how heat treatments commonly applied to hypoeutectoid cast steels, to improve their mechanical performance, can be used to also enhance electromagnetic properties of these alloys. The use of cast steels allows the creation of DC components for electrical machines not possible by the widely used method of stacking of electrical grade sheet steels. - Highlights: • A range of structural steels had their

Controlling DC permeability in cast steels

International Nuclear Information System (INIS)

Sumner, Aaran; Gerada, Chris; Brown, Neil; Clare, Adam

2017-01-01

Annealing (at multiple cooling rates) and quenching (with tempering) was performed on specimens of cast steel of varying composition. The aim was to devise a method for selecting the steel with the highest permeability, from any given range of steels, and then increasing the permeability by heat treatment. Metallographic samples were imaged using optical microscopy to show the effect of the applied heat treatments on the microstructure. Commonly cast steels can have DC permeability altered by the careful selection of a heat treatment. Increases of up to 381% were achieved by annealing using a cooling rate of 6.0 °C/min. Annealing was found to cause the carbon present in the steel to migrate from grain boundaries and from within ferrite crystals into adjacent pearlite crystals. The migration of the carbon resulted in less carbon at grain boundaries and within ferrite crystals reducing the number of pinning sites between magnetic domains. This gives rise to a higher permeability. Quenching then tempering was found to cause the formation of small ferrite crystals with the carbon content of the steel predominately held in the martensitic crystal structures. The results show that with any given range of steel compositions the highest baseline DC permeability will be found with the steel that has the highest iron content and the lowest carbon content. For the samples tested in this paper a cooling rate of 4.5 °C/min resulted in the relative permeability of the sample with the highest baseline permeability, AS4, increasing from 783 to 1479 at 0.5 T. This paper shows how heat treatments commonly applied to hypoeutectoid cast steels, to improve their mechanical performance, can be used to also enhance electromagnetic properties of these alloys. The use of cast steels allows the creation of DC components for electrical machines not possible by the widely used method of stacking of electrical grade sheet steels. - Highlights: • A range of structural steels had their

Effect of the Various Solvents on the In Vitro Permeability of Vitamin B

African Journals Online (AJOL)

Purpose: To investigate the effect of different solvents on the in vitro skin permeability of vitamin B12. Method: Vitamin B12 (B12) permeability experiments through rat skin pretreated with various solvents namely, propylene glycol, oleoyl macrogol-6-glycerides, propylene glycol monocaprylate and oleic acid, were performed ...

Different Methods of Predicting Permeability in Shale

DEFF Research Database (Denmark)

Mbia, Ernest Ncha; Fabricius, Ida Lykke; Krogsbøll, Anette

by two to five orders of magnitudes at lower vertical effective stress below 40 MPa as the content of clay minerals increases causing heterogeneity in shale material. Indirect permeability from consolidation can give maximum and minimum values of shale permeability needed in simulating fluid flow......Permeability is often very difficult to measure or predict in shale lithology. In this work we are determining shale permeability from consolidation tests data using Wissa et al., (1971) approach and comparing the results with predicted permeability from Kozeny’s model. Core and cuttings materials...... effective stress to 9 μD at high vertical effective stress of 100 MPa. The indirect permeability calculated from consolidation tests falls in the same magnitude at higher vertical effective stress, above 40 MPa, as that of the Kozeny model for shale samples with high non-clay content ≥ 70% but are higher...

PERMEABLE TREATMENT WALL EFFECTIVENESS MONITORING PROJECT, NEVADA STEWART MINE

Science.gov (United States)

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...

Permeability prediction in chalks

DEFF Research Database (Denmark)

Alam, Mohammad Monzurul; Fabricius, Ida Lykke; Prasad, Manika

2011-01-01

The velocity of elastic waves is the primary datum available for acquiring information about subsurface characteristics such as lithology and porosity. Cheap and quick (spatial coverage, ease of measurement) information of permeability can be achieved, if sonic velocity is used for permeability p...... significantly using the effective specific surface as the fluid-flow concept. The FZI unit is appropriate for highly permeable sedimentary rocks such as sandstones and limestones that have small surface areas....

Pore Structure and Effective Permeability of Metallic Filters

Czech Academy of Sciences Publication Activity Database

Hejtmánek, Vladimír; Veselý, M.; Čapek, P.

2013-01-01

Roč. 410, č. 2013 (2013), 012110 ISSN 1742-6588. [International Conference on Mathematical Modelling in Physical Sciences (IC-MSQUARE) /1./. Budapest, 03.09.2012-07.09.2012] R&D Projects: GA ČR(CZ) GAP204/11/1206 Institutional support: RVO:67985858 Keywords : stochastic reconstruction * porous media * effective permeability Subject RIV: CF - Physical ; Theoretical Chemistry

Stem sapwood permeability in relation to crown dominance and site quality in self-thinning fire-origin lodgepole pine stands.

Science.gov (United States)

Reid, Douglas E B; Silins, Uldis; Lieffers, Victor J

2003-08-01

Stem sapwood hydraulic permeability, tree leaf area, sapwood basal area, earlywood to latewood ratio of annual rings, radial variation in hydraulic permeability and stem hydraulic capacity were examined in dominant (D), codominant (CD) and suppressed (SP) lodgepole pine (Pinus contorta Dougl. ex Loud.) trees growing on medium and poor sites. Hydraulic permeability on a sapwood area basis (ks) was lower in suppressed trees (0.71 x 10(-12) m2) compared to dominants (1.97 x 10(-12) m2) and codominants (1.79 x 10(-12) m2), and higher on medium than on poor sites. The leaf/sapwood area ratio (S) varied with crown dominance position (D > CD > SP) but not by site type. Leaf specific conductivity (kL) did not vary between crown classes or site types. The relationship between leaf area and stem hydraulic supply capacity (Q*) was strong, but differed among crown classes. Dominant trees and trees from the medium sites had a greater proportion of earlywood in outer rings of sapwood than suppressed trees. Sapwood permeability declined from the cambium to the sapwood-heartwood boundary in all samples, but the decline was more gradual in dominant trees compared to codominant and suppressed trees; differences in the radial variation in sapwood permeability may be related to differences in S. Sapwood permeability is positively related to crown dominance, whereas subdominant (CD and SP) trees have greater Q* in relation to leaf area, leading us to propose that this may give subdominant trees a survival advantage, slowing self-thinning.

Regional-dependent intestinal permeability and BCS classification: elucidation of pH-related complexity in rats using pseudoephedrine.

Science.gov (United States)

Fairstein, Moran; Swissa, Rotem; Dahan, Arik

2013-04-01

Based on its lower Log P value relative to metoprolol, a marker for the low/high-permeability (P(eff)) class boundary, pseudoephedrine was provisionally classified as BCS low-permeability compound. On the other hand, following oral administration, pseudoephedrine fraction dose absorbed (F(abs)) and systemic bioavailability approaches 100%. This represents a challenge to the generally recognized P(eff)-F(abs) correlation. The purpose of this study was to elucidate the underlying mechanisms behind the confusion in pseudoephedrine's BCS classification. Pseudoephedrine's BCS solubility class was determined, and its physicochemical properties and intestinal permeability were thoroughly investigated, both in vitro and in vivo in rats, considering the complexity of the whole of the small intestine. Pseudoephedrine was found to be unequivocally a high-solubility compound. All of the permeability studies revealed similar phenomenon; at any given intestinal segment/pH, the permeability of metoprolol was higher than that of pseudoephedrine, however, as the intestinal region becomes progressively distal, and the pH gradually increases, pseudoephedrine's permeability rises above that of metoprolol in the former segment. This unique permeability pattern likely explains pseudoephedrine's complete absorption. In conclusion, pseudoephedrine is a BCS Class I compound; no discrepancy between P(eff) and F(abs) is involved in its absorption. Rather, it reflects the complexity behind P(eff) when considering the whole of the intestine. We propose to allow high-permeability classification to drugs with P(eff) that matches/exceeds the low/high class benchmark anywhere throughout the intestinal tract and not restricted necessarily to the jejunum.

A lattice Boltzmann investigation of steady-state fluid distribution, capillary pressure and relative permeability of a porous medium: Effects of fluid and geometrical properties

Science.gov (United States)

Li, Zi; Galindo-Torres, Sergio; Yan, Guanxi; Scheuermann, Alexander; Li, Ling

2018-06-01

Simulations of simultaneous steady-state two-phase flow in the capillary force-dominated regime were conducted using the state-of-the-art Shan-Chen multi-component lattice Boltzmann model (SCMC-LBM) based on two-dimensional porous media. We focused on analyzing the fluid distribution (i.e., WP fluid-solid, NP fluid-solid and fluid-fluid interfacial areas) as well as the capillary pressure versus saturation curve which was affected by fluid and geometrical properties (i.e., wettability, adhesive strength, pore size distribution and specific surface area). How these properties influenced the relative permeability versus saturation relation through apparent effective permeability and threshold pressure gradient was also explored. The SCMC-LBM simulations showed that, a thin WP fluid film formed around the solid surface due to the adhesive fluid-solid interaction, resulting in discrete WP fluid distributions and reduction of the WP fluid mobility. Also, the adhesive interaction provided another source of capillary pressure in addition to capillary force, which, however, did not affect the mobility of the NP fluid. The film fluid effect could be enhanced by large adhesive strength and fine pores in heterogeneous porous media. In the steady-state infiltration, not only the NP fluid but also the WP fluid were subjected to the capillary resistance. The capillary pressure effect could be alleviated by decreased wettability, large average pore radius and improved fluid connectivity in heterogeneous porous media. The present work based on the SCMC-LBM investigations elucidated the role of film fluid as well as capillary pressure in the two-phase flow system. The findings have implications for ways to improve the macroscopic flow equation based on balance of force for the steady-state infiltration.

Effect of Matrix-Wellbore Flow and Porosity on Pressure Transient Response in Shale Formation Modeling by Dual Porosity and Dual Permeability System

Directory of Open Access Journals (Sweden)

Daolun Li

2015-01-01

Full Text Available A mathematical dual porosity and dual permeability numerical model based on perpendicular bisection (PEBI grid is developed to describe gas flow behaviors in shale-gas reservoirs by incorporating slippage corrected permeability and adsorbed gas effect. Parametric studies are conducted for a horizontal well with multiple infinite conductivity hydraulic fractures in shale-gas reservoir to investigate effect of matrix-wellbore flow, natural fracture porosity, and matrix porosity. We find that the ratio of fracture permeability to matrix permeability approximately decides the bottom hole pressure (BHP error caused by omitting the flow between matrix and wellbore and that the effect of matrix porosity on BHP is related to adsorption gas content. When adsorbed gas accounts for large proportion of the total gas storage in shale formation, matrix porosity only has a very small effect on BHP. Otherwise, it has obvious influence. This paper can help us understand the complex pressure transient response due to existence of the adsorbed gas and help petroleum engineers to interpret the field data better.

Regional-Dependent Intestinal Permeability and BCS Classification: Elucidation of pH-Related Complexity in Rats Using Pseudoephedrine

OpenAIRE

Fairstein, Moran; Swissa, Rotem; Dahan, Arik

2013-01-01

Based on its lower Log P value relative to metoprolol, a marker for the low/high-permeability (Peff) class boundary, pseudoephedrine was provisionally classified as BCS low-permeability compound. On the other hand, following oral administration, pseudoephedrine fraction dose absorbed (Fabs) and systemic bioavailability approaches 100%. This represents a challenge to the generally recognized Peff–Fabs correlation. The purpose of this study was to elucidate the underlying mechanisms behind the ...

The Effect of Excipients on the Permeability of BCS Class III Compounds and Implications for Biowaivers

OpenAIRE

Parr, Alan; Hidalgo, Ismael J.; Bode, Chris; Brown, William; Yazdanian, Mehran; Gonzalez, Mario A.; Sagawa, Kazuko; Miller, Kevin; Jiang, Wenlei; Stippler, Erika S.

2015-01-01

Purpose Currently, the FDA allows biowaivers for Class I (high solubility and high permeability) and Class III (high solubility and low permeability) compounds of the Biopharmaceutics Classification System (BCS). Scientific evidence should be provided to support biowaivers for BCS Class I and Class III (high solubility and low permeability) compounds. Methods Data on the effects of excipients on drug permeability are needed to demonstrate that commonly used excipients do not affect the permea...

The effect of offset on fracture permeability of rocks from the Southern Andes Volcanic Zone, Chile

Science.gov (United States)

Pérez-Flores, P.; Wang, G.; Mitchell, T. M.; Meredith, P. G.; Nara, Y.; Sarkar, V.; Cembrano, J.

2017-11-01

The Southern Andes Volcanic Zone (SVZ) represents one of the largest undeveloped geothermal provinces in the world. Development of the geothermal potential requires a detailed understanding of fluid transport properties of its main lithologies. The permeability of SVZ rocks is altered by the presence of fracture damage zones produced by the Liquiñe-Ofqui Fault System (LOFS) and the Andean Transverse Faults (ATF). We have therefore measured the permeability of four representative lithologies from the volcanic basement in this area: crystalline tuff, andesitic dike, altered andesite and granodiorite. For comparative purposes, we have also measured the permeability of samples of Seljadalur basalt, an Icelandic rock with widely studied and reported hydraulic properties. Specifically, we present the results of a systematic study of the effect of fractures and fracture offsets on permeability as a function of increasing effective pressure. Baseline measurements on intact samples of SVZ rocks show that the granodiorite has a permeability (10-18 m2), two orders of magnitude higher than that of the volcanic rocks (10-20 m2). The presence of throughgoing mated macro-fractures increases permeability by between four and six orders of magnitude, with the highest permeability recorded for the crystalline tuff. Increasing fracture offset to produce unmated fractures results in large increases in permeability up to some characteristic value of offset, beyond which permeability changes only marginally. The increase in permeability with offset appears to depend on fracture roughness and aperture, and these are different for each lithology. Overall, fractured SVZ rocks with finite offsets record permeability values consistent with those commonly found in geothermal reservoirs (>10-16 m2), which potentially allow convective/advective flow to develop. Hence, our results demonstrate that the fracture damage zones developed within the SVZ produce permeable regions, especially within the

Group boundary permeability moderates the effect of a dependency meta-stereotype on help-seeking behaviour.

Science.gov (United States)

Zhang, Lange; Kou, Yu; Zhao, Yunlong; Fu, Xinyuan

2016-08-01

Previous studies have found that when low-status group members are aware that their in-group is stereotyped as dependent by a specific out-group (i.e. a dependency meta-stereotype is salient), they are reluctant to seek help from the high-status out-group to avoid confirming the negative meta-stereotype. However, it is unclear whether low-status group members would seek more help in the context of a salient dependency meta-stereotype when there is low (vs. high) group boundary permeability. Therefore, we conducted two experiments to examine the moderating effect of permeability on meta-stereotype confirmation with a real group. In study 1, we manipulated the salience of the dependency meta-stereotype, measured participants' perceived permeability and examined their help-seeking behaviour in a real-world task. Participants who perceived low permeability sought more help when the meta-stereotype was salient (vs. not salient), whereas participants who perceived high permeability sought the same amount of help across conditions. In study 2, we manipulated the permeability levels and measured the dependency meta-stereotype. Participants who endorsed a high-dependency meta-stereotype sought more help than participants who endorsed a low-dependency meta-stereotype; this effect was particularly strong in the low-permeability condition. The implications of these results for social mobility and intergroup helping are discussed. © 2015 International Union of Psychological Science.

Effectiveness of semi-permeable dressings to treat radiation-induced skin reactions. A systematic review.

Science.gov (United States)

Fernández-Castro, M; Martín-Gil, B; Peña-García, I; López-Vallecillo, M; García-Puig, M E

2017-11-01

The aim of this systematic review is to assess the available evidence concerning the effectiveness of semi-permeable dressings, on the full range of skin reactions, related to radiation therapy in cancer patients, from local erythema to moist desquamation, including subjective symptoms such as pain, discomfort, itchiness, burning and the effect on daily life activities. The bibliographic search was carried out looking for Randomised Clinical Trials (RCTs) indexed in PubMed, Cinhal, Cochrane plus and Biblioteca Nacional de Salud, published in the English and Spanish language, between 2010 and 2015. Data extraction and evaluation of study quality was undertaken by peer reviewers using the Critical Appraisal Skills Programme (CASP). Of 181 studies, nine full texts were assessed. Finally, six RCT were included in the final synthesis: three analysed the application of Mepilex ® Lite in breast cancer and head & neck cancer; one evaluated the application of Mepitel ® Film in breast cancer; and two assessed the use of silver nylon dressings in breast cancer and in patients with lower gastrointestinal cancer. The results show that semi-permeable dressings are beneficial in the management of skin toxicity related to radiation therapy. However, rigorous trials showing stronger evidence are needed. © 2017 John Wiley & Sons Ltd.

The Effect of DA-6034 on Intestinal Permeability in an Indomethacin-Induced Small Intestinal Injury Model.

Science.gov (United States)

Kwak, Dong Shin; Lee, Oh Young; Lee, Kang Nyeong; Jun, Dae Won; Lee, Hang Lak; Yoon, Byung Chul; Choi, Ho Soon

2016-05-23

DA-6034 has anti-inflammatory activities and exhibits cytoprotective effects in acute gastric injury models. However, explanations for the protective effects of DA-6034 on intestinal permeability are limited. This study sought to investigate the effect of DA-6034 on intestinal permeability in an indomethacin-induced small intestinal injury model and its protective effect against small intestinal injury. Rats in the treatment group received DA-6034 from days 0 to 2 and indomethacin from days 1 to 2. Rats in the control group received indomethacin from days 1 to 2. On the fourth day, the small intestines were examined to compare the severity of inflammation. Intestinal permeability was evaluated by using fluorescein isothiocyanate-labeled dextran. Western blotting was performed to confirm the association between DA-6034 and the extracellular signal-regulated kinase (ERK) pathway. The inflammation scores in the treatment group were lower than those in the control group, but the difference was statistically insignificant. Hemorrhagic lesions in the treatment group were broader than those in the control group, but the difference was statistically insignificant. Intestinal permeability was lower in the treatment group than in the control group. DA-6034 enhanced extracellular signal-regulated kinase expression, and intestinal permeability was negatively correlated with ERK expression. DA-6034 may decrease intestinal permeability in an indomethacin-induced intestinal injury model via the ERK pathway.

Permeability and dispersivity of variable-aperture fracture systems

International Nuclear Information System (INIS)

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

The effects of heavy metal ions on the chlorophyll content and cell membrane permeability of charophytes

International Nuclear Information System (INIS)

Fu Hualong; Chen Hao; Dong Bin; Qing Renwei

2001-01-01

The authors studied the effects of several heavy metal ions in different concentrations (Cd 2+ , Hg 2+ , Pb 2+ , Cr 6+ ) on the chlorophyll content and cell membrane permeability of Chara vulgaris L. It was discovered that the effects of heavy metal ions on the chlorophyll content and cell membrane permeability of Chara vulgaris L. changed with their different concentration. The trend was that the chlorophyll content and cell membrane permeability were decreased with the increase of the heavy metal ions. The degree of chlorophyll content affected was Cr 6+ , Cd 2+ , Hg 2+ , Pb 2+ , and that of cell membrane permeability affected was Cd 2+ , Cr 6+ , Hg 2+ , Pb 2+

A casting and imaging technique for determining void geometry and relative permeability behavior of a single fracture specimen

Energy Technology Data Exchange (ETDEWEB)

Cox, B.L.; Pruess, K.; Persoff, P.

1990-01-01

A casting technique has been developed for making translucent replicas of the void space of natural rock fractures. Attenuation of light shined through the cast combined with digital image analysis provides a pointwise definition of fracture apertures. The technique has been applied to a fracture specimen from Dixie Valley, Nevada, and the measured void space geometry has been used to develop theoretical predictions of two-phase relative permeability. A strong anisotropy in relative permeabilities has been found, which is caused by highly anisotropic spatial correlations among fracture apertures. 16 refs., 6 figs.

A framework for understanding semi-permeable barrier effects on migratory ungulates

Science.gov (United States)

Sawyer, Hall; Kauffman, Matthew J.; Middleton, Arthur D.; Morrison, Thomas A.; Nielson, Ryan M.; Wyckoff, Teal B.

2013-01-01

1. Impermeable barriers to migration can greatly constrain the set of possible routes and ranges used by migrating animals. For ungulates, however, many forms of development are semi-permeable, and making informed management decisions about their potential impacts to the persistence of migration routes is difficult because our knowledge of how semi-permeable barriers affect migratory behaviour and function is limited. 2. Here, we propose a general framework to advance the understanding of barrier effects on ungulate migration by emphasizing the need to (i) quantify potential barriers in terms that allow behavioural thresholds to be considered, (ii) identify and measure behavioural responses to semi-permeable barriers and (iii) consider the functional attributes of the migratory landscape (e.g. stopovers) and how the benefits of migration might be reduced by behavioural changes. 3. We used global position system (GPS) data collected from two subpopulations of mule deer Odocoileus hemionus to evaluate how different levels of gas development influenced migratory behaviour, including movement rates and stopover use at the individual level, and intensity of use and width of migration route at the population level. We then characterized the functional landscape of migration routes as either stopover habitat or movement corridors and examined how the observed behavioural changes affected the functionality of the migration route in terms of stopover use. 4. We found migratory behaviour to vary with development intensity. Our results suggest that mule deer can migrate through moderate levels of development without any noticeable effects on migratory behaviour. However, in areas with more intensive development, animals often detoured from established routes, increased their rate of movement and reduced stopover use, while the overall use and width of migration routes decreased. 5. Synthesis and applications. In contrast to impermeable barriers that impede animal movement

Inclusion of Topological Measurements into Analytic Estimates of Effective Permeability in Fractured Media

Science.gov (United States)

Sævik, P. N.; Nixon, C. W.

2017-11-01

We demonstrate how topology-based measures of connectivity can be used to improve analytical estimates of effective permeability in 2-D fracture networks, which is one of the key parameters necessary for fluid flow simulations at the reservoir scale. Existing methods in this field usually compute fracture connectivity using the average fracture length. This approach is valid for ideally shaped, randomly distributed fractures, but is not immediately applicable to natural fracture networks. In particular, natural networks tend to be more connected than randomly positioned fractures of comparable lengths, since natural fractures often terminate in each other. The proposed topological connectivity measure is based on the number of intersections and fracture terminations per sampling area, which for statistically stationary networks can be obtained directly from limited outcrop exposures. To evaluate the method, numerical permeability upscaling was performed on a large number of synthetic and natural fracture networks, with varying topology and geometry. The proposed method was seen to provide much more reliable permeability estimates than the length-based approach, across a wide range of fracture patterns. We summarize our results in a single, explicit formula for the effective permeability.

Two-phase flow in porous media: power-law scaling of effective permeability

Energy Technology Data Exchange (ETDEWEB)

Groeva, Morten; Hansen, Alex, E-mail: Morten.Grova@ntnu.no, E-mail: Alex.Hansen@ntnu.no [Department of Physics, NTNU, NO-7491 Trondheim (Norway)

2011-09-15

A recent experiment has reported power-law scaling of effective permeability of two-phase flow with respect to capillary number for a two-dimensional model porous medium. In this paper, we consider the simultaneous flow of two phases through a porous medium under steady-state conditions, fixed total flow-rate and saturation, using a two-dimensional network simulator. We obtain power-law exponents for the scaling of effective permeability with respect to capillary number. The simulations are performed both for viscosity matched fluids and for a high viscosity ratio resembling that of air and water. Good power-law behaviour is found for both cases. Different exponents are found, depending on saturation.

Intestinal mucosal permeability of severely underweight and nonmalnourished Bangladeshi children and effects of nutritional rehabilitation.

Science.gov (United States)

Hossain, Md Iqbal; Nahar, Baitun; Hamadani, Jena D; Ahmed, Tahmeed; Roy, Anjan Kumar; Brown, Kenneth H

2010-11-01

Lactulose/mannitol (L/M) intestinal permeability tests were completed to compare the intestinal function of severely underweight children recovering from diarrhea and other illnesses and of nonmalnourished children from the same communities, and to evaluate the effects of food supplementation, with or without psychosocial stimulation, on the changes in intestinal function among the underweight children. Seventy-seven malnourished children completed intestinal permeability studies at baseline and 3 months after receiving 1 of the following randomly assigned treatment regimens: group-C--fortnightly follow-up at community-based follow-up units, including growth monitoring and promotion, health education, and micronutrient supplementation, n = 17; group-SF--same as group-C plus supplementary food (SF) to provide 150 to 300 kcal/day, n = 23; group-PS--same as group-C plus psychosocial stimulation (PS), n = 17; or group-SF + PS--same as group-C plus SF and PS, n = 20. Seventeen nonmalnourished children were included as comparison subjects. The malnourished children's mean ± SD initial age was 13.1 ± 4.0 months, their mean weight-for-age z score was -3.82 ± 0.61, and their median (interquartile range) urinary L/M recovery ratio was 0.16 (0.10-0.28). Eighty-four percent of the children had L/M ≥ 0.07, suggestive of impaired intestinal function. The median L/M of the malnourished children was significantly greater than that of 17 relatively well-nourished children (median 0.09; interquartile range 0.05-0.12; P = 0.001). There were no significant differences in baseline characteristics of the severely malnourished children by treatment group. Following treatment, the L/M ratio improved in all of the groups (P sugar permeability, is impaired among severely underweight children. Intestinal permeability improves in relation to weight gain, but intestinal mucosal recovery is not specifically related to the types or amount of food supplementation or PS provided in this trial.

Making synthetic mudstone: Parametric resedimentation studies at high effective stress to determine controls on breakthrough pressure and permeability

Science.gov (United States)

Guiltinan, E. J.; Cardenas, M. B.; Cockrell, L.; Espinoza, N.

2017-12-01

The geologic sequestration of CO2 is widely considered a potential solution for decreasing anthropogenic atmospheric CO2 emissions. As CO2 rises buoyantly within a reservoir it pools beneath a caprock and a pressure is exerted upon the pores of the caprock proportionally to the height of the pool. The breakthrough pressure is the point at which CO2 begins to flow freely across the caprock. Understanding the mineralogical and grain size controls on breakthrough pressure is important for screening the security of CO2 sequestration sites. However, breakthrough pressure and permeability measurements on caprocks are difficult to conduct in a systematic manner given the variability in and heterogeneity of naturally occurring mudstones and shales causing significant noise and scatter in the literature. Recent work has even revealed the ability for CO2 to pass through thin shale beds at relatively low pressures. To broaden the understanding of shale breakthrough and permeability, we developed an approach that allows for the creation of resedimented mudstones at high effective stresses. Resedimented samples also include calcium carbonate cement. Using this technique, we explore the controls on entry pressure, breakthrough pressure, and permeability of synthetic mudstones. Understanding the effect of mineralogy and grain size on the permeability and breakthrough pressure of mudstones at reservoir stresses will help in the selection and uncertainty quantification of secure CO2 storage sites.

Wetting phase permeability in a partially saturated horizontal fracture

International Nuclear Information System (INIS)

Nicholl, M.J.; Glass, R.J.

1994-01-01

Fractures within geologic media can dominate the hydraulic properties of the system. Therefore, conceptual models used to assess the potential for radio-nuclide migration in unsaturated fractured rock such as that composing Yucca Mountain, Nevada, must be consistent with flow processes in individual fractures. A major obstacle to the understanding and simulation of unsaturated fracture flow is the paucity of physical data on both fracture aperture structure and relative permeability. An experimental procedure is developed for collecting detailed data on aperture and phase structure from a transparent analog fracture. To facilitate understanding of basic processes and provide a basis for development of effective property models, the simplest possible rough-walled fracture is used. Stable phase structures of varying complexity are created within the horizontal analog fracture. Wetting phase permeability is measured under steady-state conditions. A process based model for wetting phase relative permeability is then explored. Contributions of the following processes to reduced wetting phase permeability under unsaturated conditions are considered: reduction in cross-sectional flow area, increased path length, localized flow restriction, and preferential occupation of large apertures by the non-wetting phase

High-permeability criterion for BCS classification: segmental/pH dependent permeability considerations.

Science.gov (United States)

Dahan, Arik; Miller, Jonathan M; Hilfinger, John M; Yamashita, Shinji; Yu, Lawrence X; Lennernäs, Hans; Amidon, Gordon L

2010-10-04

The FDA classifies a drug substance as high-permeability when the fraction of dose absorbed (F(abs)) in humans is 90% or higher. This direct correlation between human permeability and F(abs) has been recently controversial, since the β-blocker sotalol showed high F(abs) (90%) and low Caco-2 permeability. The purpose of this study was to investigate the scientific basis for this disparity between permeability and F(abs). The effective permeabilities (P(eff)) of sotalol and metoprolol, a FDA standard for the low/high P(eff) class boundary, were investigated in the rat perfusion model, in three different intestinal segments with pHs corresponding to the physiological pH in each region: (1) proximal jejunum, pH 6.5; (2) mid small intestine, pH 7.0; and (3) distal ileum, pH 7.5. Both metoprolol and sotalol showed pH-dependent permeability, with higher P(eff) at higher pH. At any given pH, sotalol showed lower permeability than metoprolol; however, the permeability of sotalol determined at pH 7.5 exceeded/matched metoprolol's at pH 6.5 and 7.0, respectively. Physicochemical analysis based on ionization, pK(a) and partitioning of these drugs predicted the same trend and clarified the mechanism behind these observed results. Experimental octanol-buffer partitioning experiments confirmed the theoretical curves. An oral dose of metoprolol has been reported to be completely absorbed in the upper small intestine; it follows, hence, that metoprolol's P(eff) value at pH 7.5 is not likely physiologically relevant for an immediate release dosage form, and the permeability at pH 6.5 represents the actual relevant value for the low/high permeability class boundary. Although sotalol's permeability is low at pH 6.5 and 7.0, at pH 7.5 it exceeds/matches the threshold of metoprolol at pH 6.5 and 7.0, most likely responsible for its high F(abs). In conclusion, we have shown that, in fact, there is no discrepancy between P(eff) and F(abs) in sotalol's absorption; the data emphasize that

Developments in permeable and low permeability barriers

International Nuclear Information System (INIS)

Jefferis, S.A.; Norris, G.H.; Thomas, A.O.

1997-01-01

The concept of the reactive treatment zone whereby pollutants are attenuated as they move along a pathway in the ground has enabled a re-thinking of many of the concepts of containment. In particular it offers the potential for the control of the flux from a contaminated area by controlling the contaminant concentration in the pathway(s) as well as or instead of using a low permeability barrier. The paper outlines the basic concepts of the reactive treatment zone and the use of permeable and low permeability reactive systems. The paper then gives a case history of the installation of a permeable barrier using an in-situ reaction chamber

Synthesis of Plate-Like Nanoalumina and Its Effect on Gas Permeability of Carbon Fiber Epoxy Composite

Directory of Open Access Journals (Sweden)

Ghadamali Karimi Khozani

2017-03-01

Full Text Available In recent years considerable efforts have been made to develop gas impermeable polymer systems. Compared with metal system counterparts they have advantages such as low density and production costs. The most important challenge in development of impermeable polymer systems is to reduce their gas permeability by proper selection of system composition and process conditions. In this work, nanoparticles were initially synthesized using Al (NO33•9H2O and sodium dodecyl sulfate as a structure-directing agent via hydrothermal method and a plate-like structure was characterized by FESEM and EDAX analyses. In the second step, epoxy/plate-like nanoalumina nanocomposites and epoxy-carbon fiber composites containing 1, 2.5, and 5 wt% nanoalumina were prepared. The effect of nanoparticle loading level on permeability of nitrogen, argon, and carbon dioxide in epoxy/plate-like nanoalumina nanocomposites was investigated. It was observed that the permeability of epoxy/plate-like nanoalumina nanocomposites toward nitrogen, argon, and carbon dioxide gases reduced 83%, 74%, and 50%, respectively. It was deduced that the permeability reduction was clearly associated with the diameter of gas molecules. Generally speaking, the results showed that the incorporation of plate-like nanoalumina particles significantly reduced the gas permeability. Also, carbon dioxide gas permeability of carbon fiber epoxy composites containing plate-like nanoalumina was investigated to show the effect of ingredients on the gas permeability of the system. The results indicated that carbon dioxide gas permeability of epoxy carbon fiber composite containing 5 wt% of plate-like nanoalumina was totally reduced 84%.

Effect of fluid supplementation and modality on peritoneal permeability characteristics in a rat peritoneal dialysis model

NARCIS (Netherlands)

Zweers, M. M.; Splint, L. J.; Krediet, R. T.; Struijk, D. G.

2001-01-01

OBJECTIVE: Hemoconcentration may influence peritoneal permeability parameters in anesthetized animals without fluid supplementation. Therefore, the aim of this study was to investigate the effects of fluid supplementation on peritoneal permeability in an acute peritoneal dialysis model in

Effects of water activity and low molecular weight humectants on skin permeability and hydration dynamics - a double-blind, randomized and controlled study.

Science.gov (United States)

Albèr, C; Buraczewska-Norin, I; Kocherbitov, V; Saleem, S; Lodén, M; Engblom, J

2014-10-01

The mammalian skin is a barrier that effectively separates the water-rich interior of the body from the normally dryer exterior. Changes in the external conditions, for example ambient humidity, have been shown to affect the skin barrier properties. The prime objective of this study was to evaluate the effect of water activity of a topical formulation on skin hydration and permeability. A second objective was to gain more understanding on how two commonly used humectants, urea and glycerol, affect skin barrier function in vivo. Simple aqueous formulations were applied under occlusion to the volar forearm of healthy volunteers. Following 4-h exposure, skin water loss (by transepidermal water loss measurements), skin hydration (by Corneometry) and skin permeability (by time to vasodilation due to benzyl nicotinate exposure) were monitored. The results demonstrate that a relatively small change in the water activity of a topical formulation is sufficient to induce considerable effects on stratum corneum hydration and permeability to exogenous substances. Exposing the skin to high water activity leads to increased skin hydration and also increased permeability. Furthermore, urea and glycerol promote skin hydration and permeability even at reduced water activity of the applied formulation. These results highlight the importance of considering the water activity in topically applied formulations and the potential benefit of using humectants. The results may impact formulation optimization in how to facilitate skin hydration and to modify skin permeability by temporarily open and close the skin barrier. © 2014 Society of Cosmetic Scientists and the Société Française de Cosmétologie.

Establishment of a permeability/porosity equation for salt grit and damming materials

International Nuclear Information System (INIS)

Fein, E.; Mueller-Lyda, I.; Storck, R.

1996-09-01

The flow resistance of stowing and sealing materials hinder the transport of brines in an ultimate storage site in salt rock strata. This effect can be seen when brines flow into the storage areas and when contaminated brines are pressed out of the underground structure. The main variable determining flow resistance is permeability. The convergence process induced by rock pressure reduces the size of the available residual cavern and also the permeability of the stowing and sealing materials. In the long-term safety analyses carried out so far, the interdependence between porosity and permeability in the case of salt grit was commonly described by a power function. The present investigation uses the data available until the end of 1994 to derive an improved relation between permeability and porosity for salt grit stowing material. The results obtained show that the power function used until now is still applicable with only a slight modification of parameters. In addition, the statistical distribution functions of the correlated parameters of the permeability/porosity relation were determined for the first time for a probabilistic safety analysis. (orig./DG) [de

Effect of porosity heterogeneity on the permeability and tortuosity of gas diffusion layers in polymer electrolyte membrane fuel cells

Science.gov (United States)

Nabovati, Aydin; Hinebaugh, James; Bazylak, Aimy; Amon, Cristina H.

2014-02-01

In this paper, we study the effect of porosity heterogeneity on the bulk hydrodynamic properties (permeability and tortuosity) of simulated gas diffusion layers (GDLs). The porosity distributions of the heterogeneous reconstructed samples are similar to those previously reported in the literature for Toray TGP-H 120™ GDLs. We use the lattice Boltzmann method to perform pore-level flow simulations in the reconstructed GDL samples. Using the results of pore-level simulations, the effect of porosity distribution is characterized on the predicted in- and cross-plane permeability and tortuosity. It was found that porosity heterogeneity causes a higher in-plane permeability and lower in-plane tortuosity, while the effect is opposite in the cross-plane direction, that is a lower cross-plane permeability and a higher cross-plane tortuosity. We further investigate the effect of adding poly-tetra-fluoro-ethylene (PTFE) & binder material to the reconstructed GDL samples. Three fiber volume percentages of 50, 75, and 100% are considered. Overall, increasing the fiber volume percentage reduces the predicted in- and cross-plane permeability and tortuosity values. A previously reported relationship for permeability of fibrous materials is fitted to the predicted permeability values, and the magnitude of the fitting parameter is reported as a function of fiber volume percentage.

Non-monotonic permeability variation during colloidal transport: Governing equations and analytical model

Science.gov (United States)

Chequer, L.; Russell, T.; Behr, A.; Genolet, L.; Kowollik, P.; Badalyan, A.; Zeinijahromi, A.; Bedrikovetsky, P.

2018-02-01

Permeability decline associated with the migration of natural reservoir fines impairs the well index of injection and production wells in aquifers and oilfields. In this study, we perform laboratory corefloods using aqueous solutions with different salinities in engineered rocks with different kaolinite content, yielding fines migration and permeability alteration. Unusual permeability growth has been observed at high salinities in rocks with low kaolinite concentrations. This has been attributed to permeability increase during particle detachment and re-attachment of already mobilised fines by electrostatic attraction to the rock in stagnant zones of the porous space. We refine the traditional model for fines migration by adding mathematical expressions for the particle re-attachment rate, particle detachment with delay relative to salinity decrease, and the attached-concentration-dependency of permeability. A one-dimensional flow problem that accounts for those three effects allows for an exact analytical solution. The modified model captures the observed effect of permeability increase at high water salinities in rocks with low kaolinite concentrations. The developed model matches the coreflooding data with high accuracy, and the obtained model coefficients vary within their usual intervals.

Crustal permeability

Science.gov (United States)

Gleeson, Tom; Ingebritsen, Steven E.

2016-01-01

Permeability is the primary control on fluid flow in the Earth’s crust and is key to a surprisingly wide range of geological processes, because it controls the advection of heat and solutes and the generation of anomalous pore pressures.  The practical importance of permeability – and the potential for large, dynamic changes in permeability – is highlighted by ongoing issues associated with hydraulic fracturing for hydrocarbon production (“fracking”), enhanced geothermal systems, and geologic carbon sequestration.  Although there are thousands of research papers on crustal permeability, this is the first book-length treatment.  This book bridges the historical dichotomy between the hydrogeologic perspective of permeability as a static material property and the perspective of other Earth scientists who have long recognized permeability as a dynamic parameter that changes in response to tectonism, fluid production, and geochemical reactions. 

Enhancement and inhibition effects on the corneal permeability of timolol maleate: Polymers, cyclodextrins and chelating agents.

Science.gov (United States)

Rodríguez, Isabel; Vázquez, José Antonio; Pastrana, Lorenzo; Khutoryanskiy, Vitaliy V

2017-08-30

This study investigates how both bioadhesive polymers (chitosan, hyaluronic acid and alginate) and permeability enhancers (ethylene glycol- bis(2-aminoethylether)- N, N, N', N'- tetraacetic acid (EGTA) and hydroxypropyl-ß-cyclodextrin) influence the permeability of the anti-glaucoma drug timolol maleate through ex vivo bovine corneas. Our results showed that only the permeability enhancers alone were able to increase drug permeability, whereas the polymers significantly reduced drug permeation, and however, they increased the pre-corneal residence of timolol. Ternary systems (polymer-enhancer-drug) showed a reduced drug permeability compared to the polymers alone. Fluorescence microscopy analysis of the epithelium surface confirmed there was no evidence of epithelial disruption caused by these formulations, suggesting that polymer-enhancer interactions reduce drug solubilization and counteract the disruptive effect of the permeability enhancers on the surface of the cornea. Further mucoadhesive tests, revealed a stable interaction of chitosan and hyaluronic acid with the epithelium, while alginate showed poor mucoadhesive properties. The differences in mucoadhesion correlated with the permeability of timolol maleate observed, i.e. formulations containing mucoadhesive polymers showed lower drug permeabilities. The results of the present study indicate polymers acting as an additional barrier towards drug permeability which is even more evident in the presence of permeability enhancers like EGTA and hydroxypropyl-ß-cyclodextrin. Then, this study highlights the need to adequately select additives intended for ocular applications since interactions between them can have opposite results to what expected in terms of drug permeability. Copyright © 2017 Elsevier B.V. All rights reserved.

Effect of Salt Forms of Chitosan on In Vitro Permeability ...

African Journals Online (AJOL)

Purpose: To investigate the effect of chitosan (CS) salt forms and pH condition on the transepithelial electrical resistance (TEER) of Caco-2 cell monolayer for enhanced permeability. Methods: Solutions (2 %w/v) of four different salt forms of CS-aspartate (CS-A), CS-ethylene diamine tetraacetate (CS-EDTA), ...

Experimental Study on the Effects of Stress Variations on the Permeability of Feldspar-Quartz Sandstone

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Fugang Wang

2017-01-01

Full Text Available The multistage and discontinuous nature of the injection process used in the geological storage of CO2 causes reservoirs to experience repeated loading and unloading. The reservoir permeability changes caused by this phenomenon directly impact the CO2 injection process and the process of CO2 migration in the reservoirs. Through laboratory experiments, variations in the permeability of sandstone in the Liujiagou formation of the Ordos CO2 capture and storage (CCS demonstration project were analyzed using cyclic variations in injection pressure and confining pressure and multistage loading and unloading. The variation in the micropore structure and its influence on the permeability were analyzed based on micropore structure tests. In addition, the effects of multiple stress changes on the permeability of the same type of rock with different clay minerals content were also analyzed. More attention should be devoted to the influence of pressure variations on permeability in evaluations of storage potential and studies of CO2 migration in reservoirs in CCS engineering.

Upscaling of permeability field of fractured rock system: Numerical examples

KAUST Repository

Bao, K.; Salama, Amgad; Sun, S.

2012-01-01

When the permeability field of a given porous medium domain is heterogeneous by the existence of randomly distributed fractures such that numerical investigation becomes cumbersome, another level of upscaling may be required. That is such complex permeability field could be relaxed (i.e., smoothed) by constructing an effective permeability field. The effective permeability field is an approximation to the real permeability field that preserves certain quantities and provides an overall acceptable description of the flow field. In this work, the effective permeability for a fractured rock system is obtained for different coarsening scenarios starting from very coarse mesh all the way towards the fine mesh simulation. In all these scenarios, the effective permeability as well as the pressure at each cell is obtained. The total flux at the exit boundary is calculated in all these cases, and very good agreement is obtained.

Effect of a mechanical damage on permeability and moisture diffusivity of concrete

International Nuclear Information System (INIS)

Picandet, V.

2001-12-01

The effect of a mechanical damage on transfer parameters of concrete is an original point of view on the coupling between damage and durability. The studied transfer parameters, permeability and moisture diffusivity, allow to characterize the transport ability of a porous media to convey gases or water (liquid and vapour). The theoretical framework of the measurement of these parameters and its applications to concrete is pointed out. The experimental studies are carried on three types of concrete: ordinary concrete, high performance concrete, and high performance steel fiber reinforced concrete. Two kinds of damage are considered and generated in samples: - A continuous damage of the medium, obtained by cyclic uniaxial loading. It is characterized by a loss of stiffness and results in a diffuse microcracking.- A discrete or localised damage, obtained by a diametrical compression of cylindrical specimens. It is characterized by the presence of identifiable and measurable cracks. Measurements of gas permeability are taken using a constant head, Cembureau type, permeameter. For cracked samples, the procedure and analysis of the results are changed in order to make the evaluation of their gas and water permeability. The simple imbibition and positive head imbibition are the disturbances of the moisture equilibrium, which allow the evaluation of the material diffusivity. The local moisture contents of the specimen are measured using a gamma-ray attenuation method. The analysis of profiles using Boltzmann's transformation leads to the moisture diffusivity and then to the water permeability coefficients. Measurements of gas and water permeability are compared in both cases of considered damage. In the first case, a damage - permeability relationship dependent on the fluid of percolation but valid for all concrete types studied could be worked out. (author)

Effects of Pregnant Leach Solution Temperature on the Permeability of Gravelly Drainage Layer of Heap Leaching Structures

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mehdi amini

2013-12-01

Full Text Available In copper heap leaching structures, the ore is leached by an acidic solution. After dissolving the ore mineral, the heap is drained off in the acidic solution using a drainage system (consisting of a network of perforated polyethylene pipes and gravelly drainage layers and is, then, transferred to the leaching plant for copper extraction where the copper is extracted and the remaining solution is dripped over the ore heap for re-leaching. In this process, the reaction between the acidic solution and copper oxide ore is exothermal and the pregnant leach solution (PLS, which is drained off the leaching heap, has a higher temperature than the dripped acidic solution. The PLS temperature variations cause some changes in the viscosity and density which affect the gravelly drainage layer's permeability. In this research, a special permeability measuring system was devised for determining the effects of the PLS temperature variations on the permeability coefficient of the gravelly drainage layer of heap leaching structures. The system, consisting of a thermal acid resistant element and a thermocouple, controls the PLS temperature, which helps measure the permeability coefficient of the gravelly drainage layer. The PLS and gravelly drainage layer of Sarcheshmeh copper mine heap leaching structure No. 1 were used in this study. The permeability coefficient of the gravelly soil was measured against the PLS and pure water at temperatures varying between 3°C to 60°C. Also, the viscosity and density of the PLS and pure water were measured at these temperatures and, using existing theoretical relations, the permeability coefficient of the gravel was computed. A comparison between the experimental and theoretical results revealed a good conformity between the two sets of results. Finally, a case (Taft heap leaching structure, Yazd, Iran was studied and its gravelly drainage layer was designed based on the results of the present research.

Effects of an elastic membrane on tube waves in permeable formations

Energy Technology Data Exchange (ETDEWEB)

Liu, H; Johnson, D

1996-10-01

In this paper, the modified properties were calculated for tube wave propagation in a fluid-filled borehole penetrating a permeable rock due to the presence of a mudcake which forms on the borehole wall. The mudcake was characterized by an impermeable elastic layer. The mudcake partial sealing mechanism was simulated using a finite membrane stiffness. Consequently, it was shown that the mudcake can reduce, but not eliminate, the permeability effects on the tube wave slowness and attenuation. Moreover, this paper discusses a variety of values for the relevant parameters especially the mudcake thickness and membrane stiffness. The important combinations of mudcake parameters were clarified by using an analytic expression for the low-frequency limit.

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

Science.gov (United States)

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. Copyright © 2013 Elsevier Ltd. All rights reserved.

The permeability of concrete for reactor containment vessels

International Nuclear Information System (INIS)

Mills, R.H.

1983-07-01

Review of the literature pertaining to water, water vapour and gas transmission through concrete revealed conflicting views on the mechanisms involved and the influence of mix design parameters such as initial porosities and water/cement ratio. Consideration of the effects of ageing and of construction defects in field concrete were totally neglected in published work. Permeability data from three published papers were compared with permeability calculated according to Powers. The ratio of calculated to observed permeability varied from 40 x 10 -3 to 860 x 10 -3 for one group: from 0.17 x 10 3 to 8.6 x 10 3 in the second; and from 24 x 10 3 to 142 x 10 3 for the third. There were therefore wide discrepancies within each group of data and between groups. A bibliography was prepared and an exploratory experimental programme was mounted to determine the relative importance of key parameters such as cement type, porosity and water/cement ratio. Contrary to frequently cited references it was found that permeability of concrete was not significantly influenced by water/cement ratio when the starting porosity was constant. If water/cement ratio was held constant, however, the permeability was strongly influenced by starting porosity. It was also found that with constant water/cement ratio permeability increased with cement content. The value of fly ash and blast furnace slag in partial substitution for Portland cement is neglected in the literature but it is important since such substitutions alleviate alkali-silicate reactions. Permeability of concrete was significantly decreased by partial substitution of Portland cement with fly ash but there was no benefit in the use of blast furnace slag

Effects of bioadvection by Arenicola marina on microphytobenthos in permeable sediments

NARCIS (Netherlands)

Chennu, Arjun; Volkenborn, Nils; De Beer, Dirk; Wethey, David S.; Woodin, Sarah A.; Polerecky, Lubos

2015-01-01

We used hyperspectral imaging to study short-term effects of bioturbation by lugworms (Arenicola marina) on the surficial biomass of microphytobenthos (MPB) in permeable marine sediments. Within days to weeks after the addition of a lugworm to a homogenized and recomposed sediment, the average

Permeability of porour rhyolite

Science.gov (United States)

Cashman, K.; Rust, A.; Wright, H.; Roberge, J.

2003-04-01

The development of permeability in bubble-bearing magmas determines the efficiency of volatile escape during their ascent through volcanic conduits, which, in turn, controls their explosive potential. As permeability requires bubble connectivity, relationships between permeability and porosity in silicic magmas must be controlled by the formation, growth, deformation and coalescence of their constituent bubbles. Although permeability data on porous volcanic pyroclasts are limited, the database can be greatly extended by including data for ceramic and metallic foams1. Several studies indicate that a single number does not adequately describe the permeability of a foam because inertial effects, which predominate at high flow rates, cause deviations from Darcy's law. These studies suggest that permeability is best modeled using the Forschheimer equation to determine both the Darcy permeability (k1) and the non-Darcian (k2) permeability. Importantly, at the high porosities of ceramic foams (75-95%), both k1 and k2 are strongly dependent on pore size and geometry, suggesting that measurement of these parameters provides important information on foam structure. We determined both the connected porosity (by He-pycnometry) and the permeability (k1 and k2) of rhyolitic samples having a wide range in porosity (22-85%) and vesicle textures. In general, these data support previous observations of a power law relationship between connected porosity and Darcy permeability2. In detail, variations in k1 increase at higher porosities. Similarly, k2 generally increases in both mean and standard deviation with increasing porosity. Measurements made on three mutually perpendicular cores from individual pumice clasts suggest that some of the variability can be explained by anisotropy in the vesicle structure. By comparison with ceramic foams, we suggest that the remaining variability results from differences either in average vesicle size or, more likely, in the size of apertures

Effect of the Various Solvents on the In Vitro Permeability of Vitamin ...

African Journals Online (AJOL)

HP

Purpose: To investigate the effect of different solvents on the in vitro skin permeability of vitamin B12. Method: Vitamin ... Transdermal delivery has many advantages such as avoidance ..... penetration enhancement in transdermal drug delivery ...

Influence of demagnetizing field on the permeability of soft magnetic composites

International Nuclear Information System (INIS)

Lin, G.Q.; Li, Z.W.; Chen, Linfeng; Wu, Y.P.; Ong, C.K.

2006-01-01

The influence of demagnetizing field on the effective permeability of magnetic composites has been investigated. A theoretical expression of the effective permeability has been obtained and discussed according to four typical composites with spheres, needles, flakes, and aligned prolate ellipsoidal particles. The results indicate that the demagnetizing field within the particles can reduce the effective permeability significantly. In order to increase the effective permeability, it is necessary to decrease the demagnetizing field within the particles. A linear relationship between effective permeability and volume fraction is also observed for composites filled with spherical particles at low volume fraction

Bentonite Permeability at Elevated Temperature

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Katherine A. Daniels

2017-01-01

Full Text Available Repository designs frequently favour geological disposal of radioactive waste with a backfill material occupying void space around the waste. The backfill material must tolerate the high temperatures produced by decaying radioactive waste to prevent its failure or degradation, leading to increased hydraulic conductivity and reduced sealing performance. The results of four experiments investigating the effect of temperature on the permeability of a bentonite backfill are presented. Bentonite is a clay commonly proposed as the backfill in repository designs because of its high swelling capacity and very low permeability. The experiments were conducted in two sets of purpose-built, temperature controlled apparatus, designed to simulate isotropic pressure and constant volume conditions within the testing range of 4–6 MPa average effective stress. The response of bentonite during thermal loading at temperatures up to 200 °C was investigated, extending the previously considered temperature range. The results provide details of bentonite’s intrinsic permeability, total stress, swelling pressure and porewater pressure during thermal cycles. We find that bentonite’s hydraulic properties are sensitive to thermal loading and the type of imposed boundary condition. However, the permeability change is not large and can mostly be accounted for by water viscosity changes. Thus, under 150 °C, temperature has a minimal impact on bentonite’s hydraulic permeability.

Transformable ferroelectric control of dynamic magnetic permeability

Science.gov (United States)

Jiang, Changjun; Jia, Chenglong; Wang, Fenglong; Zhou, Cai; Xue, Desheng

2018-02-01

Magnetic permeability, which measures the response of a material to an applied magnetic field, is crucial to the performance of magnetic devices and related technologies. Its dynamic value is usually a complex number with real and imaginary parts that describe, respectively, how much magnetic power can be stored and lost in the material. Control of permeability is therefore closely related to energy redistribution within a magnetic system or energy exchange between magnetic and other degrees of freedom via certain spin-dependent interactions. To avoid a high power consumption, direct manipulation of the permeability with an electric field through magnetoelectric coupling leads to high efficiency and simple operation, but remains a big challenge in both the fundamental physics and material science. Here we report unambiguous evidence of ferroelectric control of dynamic magnetic permeability in a Co /Pb (Mg1/3Nb2/3) 0.7Ti0.3O3 (Co/PMN-PT) heterostructure, in which the ferroelectric PMN-PT acts as an energy source for the ferromagnetic Co film via an interfacial linear magnetoelectric interaction. The electric field tuning of the magnitude and line shape of the permeability offers a highly localized means of controlling magnetization with ultralow power consumption. Additionally, the emergence of negative permeability promises a new way of realizing functional nanoscale metamaterials with adjustable refraction index.

Crustal permeability: Introduction to the special issue

Science.gov (United States)

Ingebritsen, Steven E.; Gleeson, Tom

2015-01-01

The topic of crustal permeability is of broad interest in light of the controlling effect of permeability on diverse geologic processes and also timely in light of the practical challenges associated with emerging technologies such as hydraulic fracturing for oil and gas production (‘fracking’), enhanced geothermal systems, and geologic carbon sequestration. This special issue of Geofluids is also motivated by the historical dichotomy between the hydrogeologic concept of permeability as a static material property that exerts control on fluid flow and the perspective of economic geologists, geophysicists, and crustal petrologists who have long recognized permeability as a dynamic parameter that changes in response to tectonism, fluid production, and geochemical reactions. Issues associated with fracking, enhanced geothermal systems, and geologic carbon sequestration have already begun to promote a constructive dialog between the static and dynamic views of permeability, and here we have made a conscious effort to include both viewpoints. This special issue also focuses on the quantification of permeability, encompassing both direct measurement of permeability in the uppermost crust and inferential permeability estimates, mainly for the deeper crust.

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

Science.gov (United States)

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

2017-02-01

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

A Reconciliation of Packed Column Permeability Data: Column Permeability as a Function of Particle Porosity

Directory of Open Access Journals (Sweden)

Hubert M. Quinn

2014-01-01

Full Text Available In his textbook teaching of packed bed permeability, Georges Guiochon uses mobile phase velocity as the fluid velocity term in his elaboration of the Darcy permeability equation. Although this velocity frame makes a lot of sense from a thermodynamic point of view, it is valid only with respect to permeability at a single theoretical boundary condition. In his more recent writings, however, Guiochon has departed from his long-standing mode of discussing permeability in terms of the Darcy equation and has embraced the well-known Kozeny-Blake equation. In this paper, his teaching pertaining to the constant in the Kozeny-Blake equation is examined and, as a result, a new correlation coefficient is identified and defined herein based on the velocity frame used in his teaching. This coefficient correlates pressure drop and fluid velocity as a function of particle porosity. We show that in their experimental protocols, Guiochon et al. have not adhered to a strict material balance of permeability which creates a mismatch of particle porosity and leads to erroneous conclusions regarding the value of the permeability coefficient in the Kozeny-Blake equation. By correcting the experimental data to properly reflect particle porosity we reconcile the experimental results of Guiochon and Giddings, resulting in a permeability reference chart which is presented here for the first time. This reference chart demonstrates that Guiochon’s experimental data, when properly normalized for particle porosity and other related discrepancies, corroborates the value of 267 for the constant in the Kozeny-Blake equation which was derived by Giddings in 1965.

Determination of hydrogen permeability in commercial and modified superalloys

Science.gov (United States)

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.

Modelling of water permeability in cementitious materials

DEFF Research Database (Denmark)

Guang, Ye; Lura, Pietro; van Breugel, K.

2006-01-01

This paper presents a network model to predict the permeability of cement paste from a numerical simulation of its microstructure. Based on a linked list pore network structure, the effective hydraulic conductivity is estimated and the fluid flow is calculated according to the Hagen-Poiseuille law....... The pressure gradient at all nodes is calculated with the Gauss elimination method and the absolute permeability of the pore network is calculated directly from Darcy's law. Finally, the permeability model is validated by comparison with direct water permeability measurements. According to this model...

Effects of GSM modulated radio-frequency electromagnetic radiation on permeability of blood-brain barrier in male & female rats.

Science.gov (United States)

Sırav, Bahriye; Seyhan, Nesrin

2016-09-01

With the increased use of mobile phones, their biological and health effects have become more important. Usage of mobile phones near the head increases the possibility of effects on brain tissue. This study was designed to investigate the possible effects of pulse modulated 900MHz and 1800MHz radio-frequency radiation on the permeability of blood-brain barrier of rats. Study was performed with 6 groups of young adult male and female wistar albino rats. The permeability of blood-brain barrier to intravenously injected evans blue dye was quantitatively examined for both control and radio-frequency radiarion exposed groups. For male groups; Evans blue content in the whole brain was found to be 0.08±0.01mg% in the control, 0.13±0.03mg% in 900MHz exposed and 0.26±0.05mg% in 1800MHz exposed animals. In both male radio-frequency radiation exposed groups, the permeability of blood-brain barrier found to be increased with respect to the controls (pradiation exposure was found more effective on the male animals (p0.01). However 900MHz pulse modulated radio-frequency exposure was found effective on the permeability of blood-brain barrier of female animals. Results have shown that 20min pulse modulated radio-frequency radiation exposure of 900MHz and 1800MHz induces an effect and increases the permeability of blood-brain barrier of male rats. For females, 900MHz was found effective and it could be concluded that this result may due to the physiological differences between female and male animals. The results of this study suggest that mobile phone radation could lead to increase the permeability of blood-brain barrier under non-thermal exposure levels. More studies are needed to demonstrate the mechanisms of that breakdown. Copyright © 2015 Elsevier B.V. All rights reserved.

Effect of Viscous Instability on Unsteady-State Relative Permeability Effet de l'instabilité visqueuse sur la perméabilité relative en régime irrégulier

Directory of Open Access Journals (Sweden)

Sarma H. K.

2006-11-01

limiting value at high values of Isr. It is evident that the relative permeability inferred from unsteady-state core floods conducted under unfavourable mobility conditions is a lumped parameter which includes the effects of viscous instabilities. Therefore, unless the laboratory displacements happens to be a fully scaled model of the field-scale displacement, the relative permeability curves generated in the laboratory would not fully describe the field behaviour. Hence, it is essential to assess the extent of instability likely to be present in the field process. If the field process involves favourable mobility ratio, the expectation is that it would be free of viscous instability. Accordingly, the laboratory tests should also be conducted under favourable mobility ratio conditions. When the field process is known to involve unfavourable mobility ratio, it would be desirable to simulate the extent of instability in laboratory tests. Unfortunately, the scaling criteria for the growth and propagation of viscous fingers are not yet fully known. However, the relative permeability curves approach a limiting value at high values of instability number and the instability numbers encountered in the field are likely to be much higher because much larger geometric size is involved. Therefore, for unfavourable mobility ratio systems, it would be desirable to conduct the laboratory displacements in the pseudostable regime, i. e. at a high value of the instability number (> 900. This can be achieved simply by using high flow rates, provided the complications of fines migration can be avoided. Cet article présente les résultats d'une étude expérimentale sur les relations entre l'ampleur de l'instabilité visqueuse lors d'une expérience de déplacement en laboratoire et la perméabilité relative déterminée à partir des mesures effectuées lors du déplacement. Les expériences de déplacement de pétrole ont été effectuées sur un sable quartzeux à confinement triaxial. On

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

Science.gov (United States)

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

2018-01-31

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

[Effect of three penetration enhancers on corneal permeability of mangiferin in vitro].

Science.gov (United States)

Liu, Rui; Liu, Zhidong; Shu, Lexin; Zhang, Chengui; Zhang, Boli

2010-12-01

To investigate the effects of labrasol, solutol HS 15 and transcutol P on the corneal permeability of mangiferin in vitro. The effects of three penetration enhancers on the corneal permeability of mangiferin were investigated in vitro by using isolated rabbit corneas. The apparent Papp enhancements were increased 1.80, 3.27, 3.41 and 4.76-folds with Lab at 1.0%, 1.5%, 2.0% and 3.0% (P < 0.01), respectively. The apparent Papp increased 1.98 and 3.07-folds with Sol at 0.2% and 0.4% (P < 0.01), respectively, but reduced with 0.010%-0.03% Trans. The Papp value of mangiferin is significantly enhanced by 1.0%-3.0% Lab, 0.2% and 0.4% Sol, however the Papp value of mangiferin is reduced by 0.01%-0.03% Trans.

The Effect of Excipients on the Permeability of BCS Class III Compounds and Implications for Biowaivers.

Science.gov (United States)

Parr, Alan; Hidalgo, Ismael J; Bode, Chris; Brown, William; Yazdanian, Mehran; Gonzalez, Mario A; Sagawa, Kazuko; Miller, Kevin; Jiang, Wenlei; Stippler, Erika S

2016-01-01

Currently, the FDA allows biowaivers for Class I (high solubility and high permeability) and Class III (high solubility and low permeability) compounds of the Biopharmaceutics Classification System (BCS). Scientific evidence should be provided to support biowaivers for BCS Class I and Class III (high solubility and low permeability) compounds. Data on the effects of excipients on drug permeability are needed to demonstrate that commonly used excipients do not affect the permeability of BCS Class III compounds, which would support the application of biowaivers to Class III compounds. This study was designed to generate such data by assessing the permeability of four BCS Class III compounds and one Class I compound in the presence and absence of five commonly used excipients. The permeability of each of the compounds was assessed, at three to five concentrations, with each excipient in two different models: Caco-2 cell monolayers, and in situ rat intestinal perfusion. No substantial increases in the permeability of any of the compounds were observed in the presence of any of the tested excipients in either of the models, with the exception of disruption of Caco-2 cell monolayer integrity by sodium lauryl sulfate at 0.1 mg/ml and higher. The results suggest that the absorption of these four BCS Class III compounds would not be greatly affected by the tested excipients. This may have implications in supporting biowaivers for BCS Class III compounds in general.

Development of a New Apparatus for Investigating Acoustic Effects on Hydraulic Properties of Low-Permeability Geo-Materials

Science.gov (United States)

Nakajima, H.; Sawada, A.; Sugita, H.; Takeda, M.; Komai, T.; Zhang, M.

2006-12-01

Remediation of polluted soils and groundwater contaminated by heavy metals and non-aqueous phase liquids has been one of the challenging issues in the field of geo-environments. In-situ removal of the contaminants from low permeable soils, such as clay strata, is particularly difficult because of the low mobility, strong adsorption, and/or other various interactions within soils. Thus current remediation techniques, such as pump- and-treat method and even eletrokinetic method, generally suffer from low recovery rates and/or economically unacceptable long remediation periods. A perspective improvement in remediation technology is to couple the electrokinetic method with an application of acoustic waves. This so-called Electro-Acoustic Soil Decontamination (EASD) method has been proposed by Battelle Columbus Labs.(Muralidhara et al. 1990). Simultaneous application of an electric field and an acoustic field may produce a synergistic effect and result in further enhancement of water transport by electro-osmosis in principle, but there is still no fundamental data for the design of EASD method in practical applications. A number of investigations have shown that an application of acoustic waves can increase hydraulic conductivity and mobility of non-aqueous phase liquids in porous media. Most of the prior and ongoing researches in this area have been focused on increasing production from declining oil and gas reservoirs. During several field tests by the oil and gas industries, increases in oil production rates by 20% or more have been reported. However, underlying physical mechanisms for acoustically enhanced fluid transport are not adequately understood. In addition, majority of the past investigations has dealt with applications of large amplitude of acoustic waves to relatively permeable soils or fractured rocks, and there is little information if acoustic wave effectively enhances flow and contaminant transport for less permeable clayey soils. To evaluate the

Study of the effects of stress sensitivity on the permeability and porosity of fractal porous media

International Nuclear Information System (INIS)

Tan, Xiao-Hua; Li, Xiao-Ping; Liu, Jian-Yi; Zhang, Lie-Hui; Fan, Zhou

2015-01-01

Flow in porous media under stress is very important in various scientific and engineering fields. It has been shown that stress plays an important role in effect of permeability and porosity of porous media. In this work, novel predictive models for permeability and porosity of porous media considering stress sensitivity are developed based on the fractal theory and mechanics of materials. Every parameter in the proposed models has clear physical meaning. The proposed models are evaluated using previously published data for permeability and porosity measured in various natural materials. The predictions of permeability and porosity show good agreement with those obtained by the available experimental data and illustrate that the proposed models can be used to characterize the flow in porous media under stress accurately. - Highlights: • Predictive models for permeability and porosity of porous media considering stress sensitivity are developed. • The fractal theory and mechanics of materials are used in these models. • The predictions of permeability and porosity show good agreement with those obtained by the available experimental data. • The proposed models can be used to characterize the flow in porous media under stress accurately

Stress dependence of permeability of intact and fractured shale cores.

Science.gov (United States)

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.

Evaluation of permeability of compacted bentonite ground considering heterogeneity by geostatistics

International Nuclear Information System (INIS)

Tanaka, Yukihisa; Nakamura, Kunihiko; Kudo, Kohji; Hironaga, Michihiko; Nakagami, Motonori; Niwase, Kazuhito; Komatsu, Shin-ichi

2007-01-01

The permeability of the bentonite ground as an engineered barrier is possibly designed to the value which is lower than that determined in terms of required performance because of heterogeneous distribution of permeability in the ground, which might be considerable when the ground is created by the compaction method. The effect of heterogeneity in the ground on the permeability of the bentonite ground should be evaluated by overall permeability of the ground, whereas in practice, the effect is evaluated by the distribution of permeability in the ground. Thus, in this study, overall permeability of the bentonite ground is evaluated from the permeability of the bentonite ground is evaluated from the permeability distribution determined using the geostatistical method with the dry density data as well as permeability data of the undisturbed sample recovered from the bentonite ground. Consequently, it was proved through this study that possibility of overestimation of permeability of the bentonite ground can be reduced if the overall permeability is used. (author)

Verification of capillary pressure functions and relative permeability equations for gas production

Energy Technology Data Exchange (ETDEWEB)

Jang, Jaewon [Arizona State Univ., Tempe, AZ (United States)

2016-10-25

The understanding of multiphase fluid flow in porous media is of great importance in many fields such as enhanced oil recovery, hydrology, CO₂ sequestration, contaminants cleanup and natural gas production from hydrate bearing sediments. However, there are many unanswered questions about the key parameters that characterize gas and water flows in porous media. The characteristics of multiphase fluid flow in porous media such as water retention curve, relative permeability, preferential fluid flow patterns and fluid-particle interaction should be taken into consideration for a fundamental understanding of the behavior of pore scale systems.

An intelligent detecting system for permeability prediction of MBR.

Science.gov (United States)

Han, Honggui; Zhang, Shuo; Qiao, Junfei; Wang, Xiaoshuang

2018-01-01

The membrane bioreactor (MBR) has been widely used to purify wastewater in wastewater treatment plants. However, a critical difficulty of the MBR is membrane fouling. To reduce membrane fouling, in this work, an intelligent detecting system is developed to evaluate the performance of MBR by predicting the membrane permeability. This intelligent detecting system consists of two main parts. First, a soft computing method, based on the partial least squares method and the recurrent fuzzy neural network, is designed to find the nonlinear relations between the membrane permeability and the other variables. Second, a complete new platform connecting the sensors and the software is built, in order to enable the intelligent detecting system to handle complex algorithms. Finally, the simulation and experimental results demonstrate the reliability and effectiveness of the proposed intelligent detecting system, underlying the potential of this system for the online membrane permeability for detecting membrane fouling of MBR.

Effects of Collar Permeability on the Field Quality of the Large Aperture Quadrupoles for the LHC

CERN Document Server

Catalan-Lasheras, N; Kirby, G; Mess, K H; Ostojic, R; Russenschuck, Stephan

2008-01-01

The LHC contains a number of large aperture quadrupoles (MQY) in the insertions. The acceptance of these magnets was based on warm magnetic measurements performed before delivery to CERN. During the series production of the MQY quadrupoles, the permeability of the collars drifted from the nominal value, and effects on the transfer function and multipole components became evident. To study the effects on the magnetic field, variable permeability of the stainless-steel collars as a function of local field and temperature was introduced into a numerical model. Comparing the results with measured data, we could isolate the contribution of permeability deviation on the magnetic field quality. The extrapolation of transfer function and field multipoles to operating temperature and current gives the necessary offsets, which are compared with measurements on a reduced set of magnets.

The effect of novel surfactants and Solutol HS 15 on paclitaxel aqueous solubility and permeability across a Caco-2 monolayer.

Science.gov (United States)

Alani, Adam W G; Rao, Deepa A; Seidel, Ron; Wang, Jian; Jiao, Jim; Kwon, Glen S

2010-08-01

The effect of novel surfactants on the aqueous solubility and the permeability of paclitaxel across a Caco-2 cell monolayer were examined in this work. The solubility and permeability of paclitaxel was evaluated in the presence of four soft surfactants (SS) KXN441, KXN424, KXN437, and KXN 337 and Solutol HS15. All surfactants increased the aqueous solubility of paclitaxel. Caco-2 cell membrane integrity in the presence of SS and Solutol HS15 was assessed by mannitol permeability and LDH release. All surfactants were tested at 0.5x CMC, 5x CMC and 1.5 mM concentrations. The effect of SSs on paclitaxel permeability was concentration dependent. At all concentrations tested, KXN 441 and Solutol HS 15 showed partially inhibition of drug efflux with no discernable change in mannitol permeability or cytotoxicity as observed with LDH release. At these concentrations, other SSs exhibited some partial efflux inhibition along with compromised membrane integrity and increasing mannitol permeability. In conclusion, all SSs were able to increase the aqueous solubility and permeability of paclitaxel across Caco-2 cells monolayer. However, KXN441 and Solutol HS15 were able to enhance paclitaxel permeability across Caco-2 monolayer without cytotoxicity. (c) 2010 Wiley-Liss, Inc. and the American Pharmacists Association

Borehole stoneley waves and permeability: Laboratory results

International Nuclear Information System (INIS)

Winkler, K.W.; Plona, T.J.; Froelich, B.; Liu, H.L.

1987-01-01

Recent interest in full waveform sonic logging has created the need for full waveform laboratory experiments on model boreholes. Of particular interest is the investigation of Stoneley waves and their interaction with permeable formations. The authors describe experimental results that show how Stoneley wave slowness and attenuation are affected by formation permeability. Both slowness and attenuation (1/Q) are observed to increase with formation permeability. This increase is frequency dependent, being greatest at low frequencies. The presence of simulated mudcakes on the borehole wall reduces the permeability effect on Stoneley waves, but does not eliminate it. The mudcake effect is frequency dependent, being greatest at low frequencies. In our experiments on rocks, the laboratory data is in qualitative agreement with theoretical predictions. In a very well characterized synthetic porous material, theory and experiment are in good quantitative agreement

Simple algorithm to estimate mean-field effects from minor differential permeability curves based on the Preisach model

International Nuclear Information System (INIS)

Perevertov, Oleksiy

2003-01-01

The classical Preisach model (PM) of magnetic hysteresis requires that any minor differential permeability curve lies under minor curves with larger field amplitude. Measurements of ferromagnetic materials show that very often this is not true. By applying the classical PM formalism to measured minor curves one can discover that it leads to an oval-shaped region on each half of the Preisach plane where the calculations produce negative values in the Preisach function. Introducing an effective field, which differs from the applied one by a mean-field term proportional to the magnetization, usually solves this problem. Complex techniques exist to estimate the minimum necessary proportionality constant (the moving parameter). In this paper we propose a simpler way to estimate the mean-field effects for use in nondestructive testing, which is based on experience from the measurements of industrial steels. A new parameter (parameter of shift) is introduced, which monitors the mean-field effects. The relation between the shift parameter and the moving one was studied for a number of steels. From preliminary experiments no correlation was found between the shift parameter and the classical magnetic ones such as the coercive field, maximum differential permeability and remanent magnetization

Synergistic permeability enhancing effect of lysophospholipids and fatty acids on lipid membranes

DEFF Research Database (Denmark)

Davidsen, Jesper; Mouritsen, O.G.; Jørgensen, K.

2002-01-01

The permeability-enhancing effects of the two surfactants, 1-paltnitoyl-2-lyso-sn-gycero-3-pllosplloclloline (lysoPPC) and palmitic acid (PA), on lipid membranes that at physiological temperatures are in the gel, fluid, and liquid-ordered phases were determined using the concentration-dependent s...

OBSERVATION AND ANALYSIS OF A PRONOUNCED PERMEABILITY AND POROSITY SCALE-EFFECT IN UNSATURATED FRACTURED TUFF

Energy Technology Data Exchange (ETDEWEB)

V. VESSELINOV; ET AL

2001-01-01

Over 270 single-hole (Guzman et al., 1996) and 44 cross-hole pneumatic injection tests (Illman et al., 1998; Illman, 1999) have been conducted at the Apache Leap Research Site (ALRS) near Superior, Arizona. They have shown that the pneumatic pressure behavior of fractured tuff at the site is amenable to analysis by methods which treat the rock as a continuum on scales ranging from meters to tens of meters, and that this continuum is representative primarily of interconnected fractures. Both the single-hole and cross-hole test results are free of skin effect. Single-hole tests have yielded estimates of air permeability at various locations throughout the tested rock volume, on a nominal support scale of about 1 m. The corresponding log permeability data exhibit spatial behavior characteristic of a random fractal and yield a kriged estimate of how these 1-m scale log permeabilities vary in three-dimensional space (Chen et al., 2000). Cross-hole tests have been analyzed by means of a three-dimensional inverse model (Vesselinov et al., 2000) in two ways: (a) by interpreting pressure records from individual borehole monitoring intervals, one at a time, while treating the rock as if it was spatially uniform; and (b) by using the inverse model to interpret pressure records from multiple tests and borehole monitoring intervals simultaneously, while treating the rock as a random fractal characterized by a power variogram. The first approach has yielded equivalent air permeabilities and air-filled porosities for a rock volume characterized by a length-scale of several tens of meters. Comparable results have been obtained by means of type-curves (Illman and Neuman, 2001). The second approach amounts to three-dimensional pneumatic tomography, or stochastic imaging, of the rock. It has yielded a high-resolution geostatistical estimate of how air permeability and air-filled porosity, defined over grid blocks having a length-scale of 1 m, vary throughout the modeled rock volume

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

Science.gov (United States)

Liu, Yong; Li, Tian; Peng, Hangyu

2018-09-01

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

Stress-dependent permeability and wave dispersion in tight cracked rocks: Experimental validation of simple effective medium models

Science.gov (United States)

Sarout, Joel; Cazes, Emilie; Delle Piane, Claudio; Arena, Alessio; Esteban, Lionel

2017-08-01

We experimentally assess the impact of microstructure, pore fluid, and frequency on wave velocity, wave dispersion, and permeability in thermally cracked Carrara marble under effective pressure up to 50 MPa. The cracked rock is isotropic, and we observe that (1) P and S wave velocities at 500 kHz and the low-strain (S waves and 9% for P waves at 1 MPa, and (4) wave dispersion virtually vanishes above 30 MPa. Assuming no interactions between the cracks, effective medium theory is used to model the rock's elastic response and its permeability. P and S wave velocity data are jointly inverted to recover the crack density and effective aspect ratio. The permeability data are inverted to recover the cracks' effective radius. These parameters lead to a good agreement between predicted and measured wave velocities, dispersion and permeability up to 50 MPa, and up to a crack density of 0.5. The evolution of the crack parameters suggests that three deformation regimes exist: (1) contact between cracks' surface asperities up to 10 MPa, (2) progressive crack closure between 10 and 30 MPa, and (3) crack closure effectively complete above 30 MPa. The derived crack parameters differ significantly from those obtained by analysis of 2-D electron microscope images of thin sections or 3-D X-ray microtomographic images of millimeter-size specimens.

Relation between histamine release and dye permeability of pulmonary blood-air barrier in x-irradiated rat

Energy Technology Data Exchange (ETDEWEB)

Yamazaki, H [Kobe Univ. (Japan). School of Medicine

1976-04-01

The histamine-release kinetics and the influence of released histamine on the permeability of the pulmonary blood-air(BA) barrier during the early period after either whole-body or thoracic x irradiation of the rat were studied. Histamine contents of skin and lung of the irradiated rat decreased rapidly, reaching a minimum at 5 h, and this histamine depletion continued for at least 7 days. Conversely, in circulating blood histamine increased during the early period of 5 h and then decreased gradually. This early increase was linear up to 500R and then became saturated between 500 and 1,000R. Administration of polymixine B (5mg/100g body weight) to rats liberated histamine similarly. Rat sera containg histamine released soon after irradiation enhanced the capillary permeability of Evans blue(EB) in the guinea pig skin reaction, which was effectively countered by pretreatment of the guinea pig with anti-histaminic pyribenzamine (29..mu..g/100g body weight), but not by anti-serotonic chlorpromazine (0.3mg/100g body weight). Similarly, perhaps only the EB-bound serum albumin (EB-albumin), that was seen in alveolar perfusate, penetrated more through the pulmonary BA-barrier with increasing x-ray dose, in parallel with the increase in blood histamine. Pyribenzamine inhibited this effect effectively, but cysteamine (a radical scavenger) did so only partially. Thus, it seems possible that at soon after x irradiation the enhanced permeability of EB-albumin through the BA barrier of rat lung is due preferentially to the pharmacologic action of released histamine and subsidiarily to radiation damage to pulmonary cells.

Herbal medicines that benefit epidermal permeability barrier function

Directory of Open Access Journals (Sweden)

Lizhi Hu

2015-06-01

Full Text Available Epidermal permeability barrier function plays a critical role in regulating cutaneous functions. Hence, researchers have been searching for effective and affordable regimens to enhance epidermal permeability barrier function. In addition to topical stratum corneum lipids, peroxisome proliferator-activated receptor, and liver X receptor ligands, herbal medicines have been proven to benefit epidermal permeability barrier function in both normal and diseased skin, including atopic dermatitis, glucocorticoid-induced skin damage, and UVB-damaged skin. The potential mechanisms by which herbal medicines improve the permeability barrier include stimulation of epidermal differentiation, lipid production, antimicrobial peptide expression, and antioxidation. Therefore, utilization of herbal medicines could be a valuable alternative approach to enhance epidermal permeability barrier function in order to prevent and/or treat skin disorders associated with permeability barrier abnormalities.

Permeable pavement study (Edison)

Data.gov (United States)

U.S. Environmental Protection Agency — While permeable pavement is increasingly being used to control stormwater runoff, field-based, side-by-side investigations on the effects different pavement types...

Thermomechanical effects on permeability for a 3-D model of YM rock

International Nuclear Information System (INIS)

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

1999-01-01

The authors estimate how thermomechanical processes affect the spatial variability of fracture permeability for a 3-D model representing Topopah Spring tuff at the nuclear-waste repository horizon in Yucca Mountain, Nevada. Using a finite-difference code, they compute thermal stress changes. They evaluate possible permeability enhancement resulting from shear slip along various mapped fracture sets after 50 years of heating, for rock in the near-field environment of the proposed repository. The results indicate permeability enhancement of a factor of 2 for regions about 10 to 30 m above drifts, for north-south striking vertical fractures. Shear slip and permeability increases of a factor of 4 can occur in regions just above drifts, for east-west striking vertical fractures. Information on how permeability may change over the lifetime of a geologic repository is important to the prediction and evaluation of repository performance

Accurate control testing for clay liner permeability

Energy Technology Data Exchange (ETDEWEB)

Mitchell, R J

1991-08-01

Two series of centrifuge tests were carried out to evaluate the use of centrifuge modelling as a method of accurate control testing of clay liner permeability. The first series used a large 3 m radius geotechnical centrifuge and the second series a small 0.5 m radius machine built specifically for research on clay liners. Two permeability cells were fabricated in order to provide direct data comparisons between the two methods of permeability testing. In both cases, the centrifuge method proved to be effective and efficient, and was found to be free of both the technical difficulties and leakage risks normally associated with laboratory permeability testing of fine grained soils. Two materials were tested, a consolidated kaolin clay having an average permeability coefficient of 1.2{times}10{sup -9} m/s and a compacted illite clay having a permeability coefficient of 2.0{times}10{sup -11} m/s. Four additional tests were carried out to demonstrate that the 0.5 m radius centrifuge could be used for linear performance modelling to evaluate factors such as volumetric water content, compaction method and density, leachate compatibility and other construction effects on liner leakage. The main advantages of centrifuge testing of clay liners are rapid and accurate evaluation of hydraulic properties and realistic stress modelling for performance evaluations. 8 refs., 12 figs., 7 tabs.

The use of reflective and permeable pavements as a potential practice for heat island mitigation and stormwater management

International Nuclear Information System (INIS)

Li, H; Harvey, J T; Holland, T J; Kayhanian, M

2013-01-01

To help address the built environmental issues of both heat island and stormwater runoff, strategies that make pavements cooler and permeable have been investigated through measurements and modeling of a set of pavement test sections. The investigation included the hydraulic and thermal performance of the pavements. The permeability results showed that permeable interlocking concrete pavers have the highest permeability (or infiltration rate, ∼0.5 cm s −1 ). The two permeable asphalt pavements showed the lowest permeability, but still had an infiltration rate of ∼0.1 cm s −1 , which is adequate to drain rainwater without generating surface runoff during most typical rain events in central California. An increase in albedo can significantly reduce the daytime high surface temperature in summer. Permeable pavements under wet conditions could give lower surface temperatures than impermeable pavements. The cooling effect highly depends on the availability of moisture near the surface layer and the evaporation rate. The peak cooling effect of watering for the test sections was approximately 15–35 °C on the pavement surface temperature in the early afternoon during summer in central California. The evaporative cooling effect on the pavement surface temperature at 4:00 pm on the third day (25 h after watering) was still 2–7 °C lower compared to that on the second day, without considering the higher air temperature on the third day. A separate and related simulation study performed by UCPRC showed that full depth permeable pavements, if designed properly, can carry both light-duty traffic and certain heavy-duty vehicles while retaining the runoff volume captured from an average California storm event. These preliminarily results indicated the technical feasibility of combined reflective and permeable pavements for addressing the built environment issues related to both heat island mitigation and stormwater runoff management. (letter)

Effective permeability in micropores from molecular simulations

International Nuclear Information System (INIS)

Botan, A.; Vermorel, R.; Brochard, L.; Hantal, G.; Pellenq, R.

2012-01-01

Document available in extended abstract form only. Despite many years' efforts and a large numbers of proposed models, the description of transport properties in clays is still an open question. The reason for this is that structurally clay is an extremely heterogeneous material. The pore size varies from a few to 20 angstroms for interlayer (micro) porosity, from 20 A to 500 A for interparticle (meso) porosity, and 500 A to μm and more for natural (macro) fractures. One further problem with the description of the transport properties is the presence of adsorption/desorption processes onto clay particles, which are coupled with swelling/shrinkage of the particles. Any volumetric changes in the particles affect the meso-pore aperture, and thus, the total permeability of the system. The various processes affecting the permeability occur on different spatial and temporal scales, that requires a multi-scale modeling approach. The most complete model to date is a dual porosity mode. Here the total flow is often written as a sum of the macropore flow and micropore flow. The flow through macro-pores is generally considered to be laminar and obeys Darcy's law, whereas flow through the matrix (micropore flow) may be modeled using Fick's law. The micropore flow involves both Knudsen and surface diffusion mechanisms. An accurate accounting of adsorption-desorption processes or the consideration of binary mixture greatly complicate analytical description. The goal of this study is to improve macro-scale model, the dual porosity model, for the transport properties of fluids in micropores from molecular simulations. The main idea is that we reproduce an experimental set-up used for permeability measurements, as illustrated in Figure 1. High density and low density regions are settled at each end of the membrane that allows to attain a steady flow. The densities in these regions are controlled by Grand Canonical Monte Carlo simulation; the molecular motions are described by

Inhibition of K+ permeability diminishes alpha 2-adrenoceptor mediated effects on norepinephrine release

International Nuclear Information System (INIS)

Zimanyi, I.; Folly, G.; Vizi, E.S.

1988-01-01

The effect of two different potassium channel blockers, 4-aminopyridine (4-AP) and quinine, on the alpha 2-adrenoceptor mediated modulation of norepinephrine (NE) release was investigated. Pairs of mouse vasa deferentia were loaded with 3 H-norepinephrine ( 3 H-NE), superfused continuously, and stimulated electrically. 4-AP (5.3 x 10(-4) M), and quinine (10(-5) M) enhanced the stimulation-evoked release of tritium significantly. The electrically induced release of radioactivity was reduced by alpha 2-adrenoceptor agonists (1-NE and xylazine) and enhanced by the alpha 2-adrenoceptor antagonist yohimbine. Both effects were affected markedly by 4-AP or quinine: the depressant action of 1-NA and xylazine was partially antagonized and the facilitatory effect of yohimbine was completely abolished during the blockade of the potassium channels. It is suggested that the blockade of the potassium permeability counteracts negative feedback modulation; therefore, it seems likely that the stimulation of alpha 2-adrenoceptors leads to an enhanced potassium permeability and hyperpolarization of varicose axon terminals

Experimental study on the response characteristics of coal permeability to pore pressure under loading and unloading conditions

Science.gov (United States)

Ye, Zhiwei; Zhang, Lei; Hao, Dingyi; Zhang, Cun; Wang, Chen

2017-10-01

In order to study the response characteristics of coal permeability to pore pressure, seepage experiments under different simulated in situ stresses on loading and unloading paths are carried out using the self-developed Gas Flow and Displacement Testing Apparatus (GFDTA) system. Based on the analysis of the experimental data, the relationship between average pore pressure and permeability is found to basically obey the function distribution of a two degree polynomial. In this paper, two aspects of the relationship between permeability and pore pressure are explained: the Klinbenberg effect and expansion, and the penetration of the initial fracture. Under low pore pressure, the decrease in the Klinbenberg effect is the main reason for the decrease in permeability with increased pore pressure. Under relatively high pore pressure, the increase in pore pressure leads to the initial fracture expansion and penetration of the coal sample, which causes an increase in permeability. In order to evaluate the sensitivity of the permeability response to pore pressure changes, the permeability dispersion and pore pressure sensitivity coefficients are defined. After the sensitivity analysis, it was concluded that the loading history changed the fracture structure of the original coal sample and reduced its permeability sensitivity to pore pressure. Under low pore pressure, the Klinbenberg effect is the reason for the decrease in pore pressure sensitivity. Lastly, the permeability-pore pressure relationship is divided into three stages to describe the different response characteristics individually.

Trench infiltration for managed aquifer recharge to permeable bedrock

Science.gov (United States)

Heilweil, V.M.; Watt, D.E.

2011-01-01

Managed aquifer recharge to permeable bedrock is increasingly being utilized to enhance resources and maintain sustainable groundwater development practices. One such target is the Navajo Sandstone, an extensive regional aquifer located throughout the Colorado Plateau of the western United States. Spreading-basin and bank-filtration projects along the sandstone outcrop's western edge in southwestern Utah have recently been implemented to meet growth-related water demands. This paper reports on a new cost-effective surface-infiltration technique utilizing trenches for enhancing managed aquifer recharge to permeable bedrock. A 48-day infiltration trench experiment on outcropping Navajo Sandstone was conducted to evaluate this alternative surface-spreading artificial recharge method. Final infiltration rates through the bottom of the trench were about 0.5 m/day. These infiltration rates were an order of magnitude higher than rates from a previous surface-spreading experiment at the same site. The higher rates were likely caused by a combination of factors including the removal of lower permeability soil and surficial caliche deposits, access to open vertical sandstone fractures, a reduction in physical clogging associated with silt and biofilm layers, minimizing viscosity effects by maintaining isothermal conditions, minimizing chemical clogging caused by carbonate mineral precipitation associated with algal photosynthesis, and diminished gas clogging associated with trapped air and biogenic gases. This pilot study illustrates the viability of trench infiltration for enhancing surface spreading of managed aquifer recharge to permeable bedrock. ?? 2010.

Effect of high density lipoproteins on permeability of rabbit aorta to low density lipoproteins

International Nuclear Information System (INIS)

Klimov, A.N.; Popov, V.A.; Nagornev, V.A.; Pleskov, V.M.

1985-01-01

A study was made on the effect of high density lipoproteins (HDL) on the permeability of rabbit aorta to low density lipoproteins (LDL) after intravenous administration of human HDL and human ( 125 I)LDL to normal and hypercholesterolemic rabbits. Evaluation of radioactivity in plasma and aorta has shown that the administration of a large dose of HDL decreased the aorta permeability rate for ( 125 I)LDL on an average by 19% in normal rabbits, and by 45% in rabbits with moderate hypercholesterolemia. A historadiographic study showed that HDL also decreased the vessel wall permeability to ( 125 I)LDL in normal and particularly in hypercholesterolemic animals. The suggestion was made that HDL at very high molar concentration can hamper LDL transportation through the intact endothelial layer into the intima due to the ability of HDL to compete with LDL in sites of low affinity on the surface of endothelial cells. (author)

Estimation of effective permeability for magnetoactive composites containing multi-chain-structured particles based on the generalized Mori–Tanaka approach

International Nuclear Information System (INIS)

Zhang, Haiyu; Wang, Xingzhe

2014-01-01

We present an analytic approach to evaluate the effective permeability of multi-chain-structured magnetic particle-filled composites which is formulated by a microstructure-based double-inclusion magnetic model with the generalized Mori–Tanaka theorem. The local magnetic field in a representative volume element (RVE) containing multi-chain-structured particles is derived by using a modified Green’s function. The average fields in the particles, in a matrix coated by particles, and in an effective medium far away from particles are rendered by homogenization of the local magnetic distributions. By means of the relation between the average magnetic field and induction, the effective magnetic permeability of magnetoactive composites is explicitly derived; it exhibits anisotropic and universal behavior. The proposed model has been compared with the available experimental data and other microstructure-based models in the literature; it shows good agreement and gives reliable predictions for magnetic particle-filled composites, especially in terms of capturing the magnetic anisotropic characteristics with respect to the multi-chain-structured particle distribution. (paper)

Pore Structure and Diagenetic Controls on Relative Permeability: Implications for Enhanced Oil Recovery and CO2 Storage

Science.gov (United States)

Feldman, J.; Dewers, T. A.; Heath, J. E.; Cather, M.; Mozley, P.

2016-12-01

Multiphase flow in clay-bearing sandstones of the Morrow Sandstone governs the efficiency of CO2 storage and enhanced oil recovery at the Farnsworth Unit, Texas. This formation is the target for enhanced oil recovery and injection of one million metric ton of anthropogenically-sourced CO2. The sandstone hosts eight major flow units that exhibit distinct microstructural characteristics due to diagenesis, including: "clean" macro-porosity; quartz overgrowths constricting some pores; ghost grains; intergranular porosity filled by microporous authigenic clay; and feldspar dissolution. We examine the microstructural controls on macroscale (core scale) relative permeability and capillary pressure behavior through: X-ray computed tomography, Robomet.3d, and focused ion beam-scanning electron microscopy imaging of the pore structure of the major flow units of the Morrow Sandstone; relative permeability and capillary pressure in the laboratory using CO2, brine, and oil at reservoir pressure and effective stress conditions. The combined data sets inform links between patterns of diagenesis and multiphase flow. These data support multiphase reservoir simulation and performance assessment by the Southwest Regional Partnership on Carbon Sequestration (SWP). Funding for this project is provided by the U.S. Department of Energy's National Energy Technology Laboratory through the SWP under Award No. DE-FC26-05NT42591. Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of Energy's National Nuclear Security Administration under contract DE-AC04-94AL85000.

Effect of Drying Method on the Permeability Coefficient of Oak Wood (Quercus infactoria

Directory of Open Access Journals (Sweden)

Shuboo Salehpour

2014-05-01

Full Text Available In this study, the effect of drying method on the permeability coefficient of the oak wood (Quercus infectoria Oliv was studied. Freshly-cut logs of oak were prepared from Oureman, the east area of Kourdistan in Iran. Then, boards with nominal thickness of 6 cm were cut. The boards were dried using two methods. In the first method, the boards were air dried to the moisture content close to FSP for 45 days and then they were kiln dried using T5-D1 schedule. In the second method, the boards were dried from green condition to the final moisture content of 10% using T5-D1 schedule. Then, the permeability coefficient in the transverse and longitudinal directions in both heartwood and sapwood regions was measured, separately. Results showed that the permeability of oak boards dried by kiln drying method both in the transverse and longitudinal directions and also in the heartwood and sapwood regions was greater than that of those dried by the combined method (air drying + kiln drying.

Thermodynamic model for grain boundary effects on hydrogen solubility, diffusivity and permeability in poly-crystalline tungsten

Energy Technology Data Exchange (ETDEWEB)

Oda, Takuji, E-mail: oda@snu.ac.kr

2016-11-15

Highlights: • A thermodynamic model to simulate grain boundary effects on hydrogen behaviors in poly-crystalline W was established. • With this model, the effective solubility, diffusivity and permeability of hydrogen are calculated as a function of grain size. • Grain boundary significantly change the hydrogen behaviors in poly-crystalline W up to around 1000 K. - Abstract: A thermodynamic model to evaluate effects of grain boundary (GB) on hydrogen behaviors in poly-crystalline tungsten is established. With this model, the effective solubility, diffusivity and permeability of hydrogen in tungsten equilibrated with surrounding H{sub 2} gas can be calculated as a function of grain size, temperature and H{sub 2} partial pressure. By setting 1.0 eV to the binding energy of hydrogen to GBs and 0.4 eV to the diffusion barrier of hydrogen along GBs, the model reasonably reproduces some experimental data on the effective diffusivity and permeability. Comparisons between calculation results by the model and available experimental data show that GBs significantly affect the hydrogen behaviors up to around 1000 K or higher in practical materials. Therefore, the effects of GBs need to be considered in analysis of experimental results, for which the present model can be utilized, and in prediction of tritium inventory and leakage in fusion reactors.

Simultaneous inversion of airborne electromagnetic data for resistivity and magnetic permeability

International Nuclear Information System (INIS)

Beard, L.P.; Nyquist, J.E.

1998-01-01

Where the magnetic permeability of rock or soil exceeds that of free space, the effect on airborne electromagnetic systems is to produce a frequency-independent shift in the in-phase response of the system while altering the quadrature response only slightly. The magnitude of the in-phase shift increases as (1) the relative magnetic permeability is increased, (2) the amount of magnetic material is increased, and (3) the airborne sensor gets nearer the earth's surface. Over resistive, magnetic ground, the shift may be evinced by negative in-phase measurements at low frequencies; but over more conductive ground, the same shift may go unnoticed because of the large positive in-phase response. If the airborne sensor is flown at low levels, the magnitude of the shift may be large enough to affect automatic inversion routines that do not take this shift into account, producing inaccurate estimated resistivities, usually overestimates. However, layered-earth inversion algorithms that incorporate magnetic permeability as an additional inversion parameter may improve the resistivity estimates. The authors demonstrate this improvement using data collected over hazardous waste sites near Oak Ridge, Tennessee, USA. Using resistivity inversion without magnetic permeability, the waste sites are almost invisible to the sensors. When magnetic permeability is included as an inversion parameter, the sites are detected, both by improved resistivity estimates and by estimated magnetic permeability

The Effect of Green Inhibitor on strength and water permeability of ...

African Journals Online (AJOL)

... present in the concrete evident from inductively coupled plasma-mass spectrometry (ICPMS) result. KOH is adequate for passivation and reduction of permeability, which serve as a chemical water barriers or hydrophobic agents. Keywords: Concrete; Calcium-Silicate-Hydrate (C-S-H); Compressive strength; Permeability; ...

Hydrogen permeability through metals

International Nuclear Information System (INIS)

Pisarev, A.A.; Tsvetkov, I.V.; Marenkov, E.D.; Yarko, S.S.

2011-01-01

The mechanisms of hydrogen permeability through one-layer and multi-layer membranes are considered. The effect of surface roughness, crystal defects, cracks and pores is described. Mathematical description of the processes is given [ru

Effect of ozone and histamine on airway permeability to horseradish peroxidase in guinea pigs

International Nuclear Information System (INIS)

Miller, P.D.; Gordon, T.; Warnick, M.; Amdur, M.O.

1986-01-01

Airway permeability was studied in groups of male guinea pigs at 2, 8, and 24 h after a 1-h exposure to 1 ppm ozone or at 2 h after a 1-h exposure to filtered air (control). Intratracheal administration of 2 mg horseradish peroxidase (HRP) was followed by blood sampling at 5-min intervals up to 30 min. The rate of appearance of HRP in plasma was significantly higher at 2 and 8 h after ozone exposure than that found in animals examined 2 h after air exposure or 24 h after ozone exposure. A dose of 0.12 mg/kg of subcutaneous histamine given after the 15 min blood sample significantly increased the already elevated permeability seen at 2 h post ozone, but had no effect on animals exposed to filtered air 2 h earlier or to ozone 24 h earlier. No difference was seen in the amount of subcutaneous radiolabeled histamine in the lungs of animals exposed 2 h earlier either to air or to ozone. These data indicate that a short-term exposure to ozone produced a reversible increase in respiratory epithelial permeability to HRP in guinea pigs. The potentiation of this increased permeability by histamine may be another manifestation of ozone-induced hyperreactivity

[Effect of multicomponent environment on intestinal permeability of puerarin in biopharmaceutics classification system of Chinese materia medica].

Science.gov (United States)

Liu, Yang; Wang, Gang; Dong, Ling; Tang, Ming-Min; Zhu, Mei-Ling; Dong, Hong-Huant; Hou, Cheng-Bo

2014-12-01

The evaluation of permeability in biopharmaceutics classification system of Chinese materia medica (CMMBCS) requires multicomponent as a whole in order to conduct research, even in the study of a specific component, should also be put in the multicomponent environment. Based on this principle, the high content components in Gegen Qinlian decoction were used as multicomponent environmental impact factors in the experiment, and the relevant parameters of intestinal permeability about puerarin were measured with using in situ single-pass intestinal perfusion model, to investigate and evaluate the intestinal permeability of puerarin with other high content components. The experimental results showed that different proportions of baicalin, glycyrrhizic acid and berberine had certain influence on intestinal permeability of puerarin, and glycyrrhizic acid could significantly inhibit the intestinal absorption of puerarin, moreover, high concentration of berberine could promote the absorption of puerarin. The research results indicated that the important research ideas of permeability evaluation in biopharmaceutics classification system of Chinese materia medica with fully considering the effects of other ingredients in multicomponent environment.

Xenon NMR measurements of permeability and tortuosity in reservoir rocks.

Science.gov (United States)

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.

Ground-water flow in low permeability environments

Science.gov (United States)

Neuzil, Christopher E.

1986-01-01

flow phenomena, osmosis and ultrafiltration, are experimentally well established in prepared clays but have been incompletely investigated, particularly in undisturbed geologic media. Small-scale experimental results form much of the basis for analyses of flow in low-permeability environments which occurs on scales of time and size too large to permit direct observation. Such large-scale flow behavior is the focus of the second part of the review. Extrapolation of small-scale experimental experience becomes an important and sometimes controversial problem in this context. In large flow systems under steady state conditions the regional permeability can sometimes be determined, but systems with transient flow are more difficult to analyze. The complexity of the problem is enhanced by the sensitivity of large-scale flow to the effects of slow geologic processes. One-dimensional studies have begun to elucidate how simple burial or exhumation can generate transient flow conditions by changing the state of stress and temperature and by burial metamorphism. Investigation of the more complex problem of the interaction of geologic processes and flow in two and three dimensions is just beginning. Because these transient flow analyses have largely been based on flow in experimental scale systems or in relatively permeable systems, deformation in response to effective stress changes is generally treated as linearly elastic; however, this treatment creates difficulties for the long periods of interest because viscoelastic deformation is probably significant. Also, large-scale flow simulations in argillaceous environments generally have neglected osmosis and ultrafiltration, in part because extrapolation of laboratory experience with coupled flow to large scales under in situ conditions is controversial. Nevertheless, the effects are potentially quite important because the coupled flow might cause ultra long lived transient conditions. The difficulties associated with analysis are

The effects of a multispecies probiotic on migraine and markers of intestinal permeability-results of a randomized placebo-controlled study

NARCIS (Netherlands)

Roos, De N.M.; Hemert, Van S.; Rovers, J.M.P.; Smits, M.G.; Witteman, B.J.M.

2017-01-01

Background/Objectives:Migraine, associated with several gastrointestinal disorders, may result from increased intestinal permeability, allowing endotoxins to enter the bloodstream. We tested whether probiotics could reduce migraine through an effect on intestinal permeability and

Effect of gas type on foam film permeability and its implications for foam flow in porous media.

Science.gov (United States)

Farajzadeh, R; Muruganathan, R M; Rossen, W R; Krastev, R

2011-10-14

The aim of this paper is to provide a perspective on the effect of gas type on the permeability of foam films stabilized by different types of surfactant and to present a critical overview of the tracer gas experiments, which is the common approach to determine the trapped fraction of foam in porous media. In these experiments some part of the gas is replaced by a "tracer gas" during the steady-state stage of the experiments and trapped fraction of foam is determined by fitting the effluent data to a capacitance mass-transfer model. We present the experimental results on the measurement of the gas permeability of foam films stabilized with five surfactants (non-ionic, anionic and cationic) and different salt concentrations. The salt concentrations assure formation of either common black (CBF) or Newton black films (NBF). The experiments are performed with different single gasses. The permeability of the CBF is in general higher than that of the NBF. This behavior is explained by the higher density of the surfactant molecules in the NBF compared to that of CBF. It is also observed that the permeability coefficient, K(cm/s), of CBF and NBF for non-ionic and cationic surfactants are similar and K is insensitive to film thickness. Compared to anionic surfactants, the films made by the non-ionic surfactant have much lower permeability while the films made by the cationic surfactant have larger permeability. This conclusion is valid for all gasses. For all types of surfactant the gas permeability of foam film is largely dependent on the dissolution of gas in the surfactant solution and increases with increasing gas solubility in the bulk liquid. The measured values of K are consistent with rapid diffusion of tracer gasses through trapped gas adjacent to flowing gas in porous media, and difficulties in interpreting the results of tracer-foam experiments with conventional capacitance models. The implications of the results for foam flow in porous media and factors leading

Effects of different desensitizing treatments on root dentin permeability

Directory of Open Access Journals (Sweden)

Raydsa Raíssa Moura ROSA

Full Text Available Abstract The objective of this study was to evaluate the effects of diode laser and a desensitizing dentifrice on dentin permeability. Fifty-two root dentin fragments were obtained (5 × 5mm and treated with 24% EDTA gel. The samples were divided into 4 groups (n = 13: G1, control (no treatment; G2, diode laser (λ = 908 nm, 1.5 W, continuous mode, 20s; G3, application of abrasive dentifrice for 1 minute (Elmex Sensitive Professional (International Gaba; and G4, application of abrasive dentifrice for 1 minute followed by irradiation with diode laser. Ten samples per group were immersed in 2% methylene blue solution for 4h. The specimens were washed, longitudinally sectioned, observed under optical microscopy, photographed and assessed based on the degree of dye leakage. The remaining samples were observed under scanning electron microscopy (SEM. The leakage data were subjected to ANOVA test, followed by Tukey’s t-test (α = 5%. Groups 2, 3 and 4 showed less dye penetration than the control group (p < 0.05, but were similar among each other. SEM images showed that dentinal tubules were open in G1, and fused and occluded in G2. Group 3 showed dentinal tubules that were occluded by the metal ions from the toothpaste. G4 presented similar characteristics to G3, and the presence of fused dentin. The diode laser and the dentifrice were effective in reducing dentinal permeability, and the combination of the two treatments did not show better results than either one used alone.

Permeability of protective coatings to tritium

International Nuclear Information System (INIS)

Braun, J.M.

1987-10-01

The permeability of four protective coatings to tritium gas and tritiated water was investigated. The coatings, including two epoxies, one vinyl and one urethane, were selected for their suitability in CANDU plant service in Ontario Hydro. Sorption rates of tritium gas into the coatings were considerably larger than for tritiated water, by as much as three to four orders of magnitude. However, as a result of the very large solubility of tritiated water in the coatings, the overall permeability to tritium gas and tritiated water are comparable, being somewhat larger for HTO. Marked differences were also evident among the four coatings, the vinyl proving to be unique in behaviour and morphology. Because of a highly porous surface structure water condensation takes place at high relative humidities, leading to an abnormally high retention of free water. Desorption rates from the four coatings were otherwise quite similar. Of practical importance was the observation that more effective desorption of tritiated water could be carried out at relatively high humidities, in this case 60%. It was believed that isotopic exchange was responsible for this phenomenon. It appears that epoxy coatings having a high pigment-to-binder ratio are most suited for coating concrete in tritium handling facilities

Effects of the air–steam mixture on the permeability of damaged concrete

Energy Technology Data Exchange (ETDEWEB)

Medjigbodo, Sonagnon [LUNAM Université, Institut de Recherche en Génie Civil et Mécanique (GeM UMR CNRS 6183), Centrale Nantes, 1 rue de la Noe, BP 92101, F-44321 CEDEX 3 Nantes (France); Darquennes, Aveline [LMT/ENS Cachan/CNRS UMR 8535/UPMC/PRES Université Sud Paris, Cachan (France); Aubernon, Corentin [LUNAM Université, Institut de Recherche en Génie Civil et Mécanique (GeM UMR CNRS 6183), Centrale Nantes, 1 rue de la Noe, BP 92101, F-44321 CEDEX 3 Nantes (France); Khelidj, Abdelhafid [LUNAM Université, Institut de Recherche en Génie Civil et Mécanique (GeM UMR CNRS 6183), IUT de Saint Nazaire, 58 rue Michel Ange, BP 420 Heinlex, F-44600 Saint-Nazaire (France); Loukili, Ahmed, E-mail: ahmed.loukili@ec-nantes.fr [LUNAM Université, Institut de Recherche en Génie Civil et Mécanique (GeM UMR CNRS 6183), Centrale Nantes, 1 rue de la Noe, BP 92101, F-44321 CEDEX 3 Nantes (France)

2013-12-15

Massive concrete structures such as the containments of nuclear power plant must maintain their tightness at any circumstances to prevent the escape of radioactive fission products into the environment. In the event of an accident like a Loss of Coolant Accident (LOCA), the concrete wall is submitted to both hydric and mechanical loadings. A new experimental device reproducing these extreme conditions (water vapor transfer, 140 °C and 5 bars) is developed in the GeM Laboratory to determine the effect of the saturation degree, the mechanical loading and the flowing fluid type on the concrete transfer properties. The experimental tests show that the previous parameters significantly affect the concrete permeability and the gas leakage rate. Their evolution as a function of the mechanical loading is characterized by two phases that are directly related to concrete microstructure and crack development.

Current and evolving approaches for improving the oral permeability of BCS Class III or analogous molecules.

Science.gov (United States)

Dave, Vivek S; Gupta, Deepak; Yu, Monica; Nguyen, Phuong; Varghese Gupta, Sheeba

2017-02-01

The Biopharmaceutics Classification System (BCS) classifies pharmaceutical compounds based on their aqueous solubility and intestinal permeability. The BCS Class III compounds are hydrophilic molecules (high aqueous solubility) with low permeability across the biological membranes. While these compounds are pharmacologically effective, poor absorption due to low permeability becomes the rate-limiting step in achieving adequate bioavailability. Several approaches have been explored and utilized for improving the permeability profiles of these compounds. The approaches include traditional methods such as prodrugs, permeation enhancers, ion-pairing, etc., as well as relatively modern approaches such as nanoencapsulation and nanosizing. The most recent approaches include a combination/hybridization of one or more traditional approaches to improve drug permeability. While some of these approaches have been extremely successful, i.e. drug products utilizing the approach have progressed through the USFDA approval for marketing; others require further investigation to be applicable. This article discusses the commonly studied approaches for improving the permeability of BCS Class III compounds.

Unsaturated and Saturated Permeabilities of Fiber Reinforcement: Critics and Suggestions

Directory of Open Access Journals (Sweden)

Chung Hae ePARK

2015-04-01

Full Text Available 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.

Fracture permeability under effect of normal and shear stress: A preliminary experimental investigation

International Nuclear Information System (INIS)

Mohanty, S.; Manteufel, R.D.; Chowdhury, A.H.

1995-01-01

The change in fracture permeability under mechanical loads have been investigated. An apparatus has been developed to measure change in fracture permeability, when a single fracture is subjected to normal and shear stress. Both radial and linear flow experiments have been conducted by modifying a direct shear test apparatus. Preliminary results suggest a 35-percent change in fracture permeability under normal stress to 8 MPa and nearly 350 percent under shear displacement of 9.9254 m (1 in.) at 5 MPa normal stress. Effort is underway to separate the permeability change due to gouge material production from that of due to dilation

Effect of a low-permeability layer on calculated gas flow at Yucca Mountain

International Nuclear Information System (INIS)

Lu, Ning; Amter, S.; Ross, B.

1990-01-01

Yucca Mountain is being studied to determine its suitability as a location for a high-level nuclear waste repository. Amter and Ross developed a model called TGIF (Topographic Induced Flow) to simulate gas flow under Yucca Mountain. The TGIF model differs significantly from previous gas flow models. It uses a governing equation that is based on the concept of freshwater head, thus avoiding the numerical problems associated with the near-cancellation of the forces due to gravity and the pressure gradient. Unlike most other models, dipping, layered media can be simulated. This paper describes a systematic sensitivity study that was designed to test several aspects of the TGIF model when used to simulate gas flow under Yucca Mountain. Values of three important inputs to the model were systematically varied to form a matrix of 80 runs. The matrix consisted of five values of permeability contrast between a bedded tuff layer and surrounding welded units (in all cases, bulk permeabilities were used to represent the combined effect of both fractures and matrix permeability), four temperature profiles representing different stages of repository cooldown, and four finite-difference grids

Effect of a low-permeability layer on calculated gas flow at Yucca Mountain

Energy Technology Data Exchange (ETDEWEB)

Lu, Ning; Amter, S.; Ross, B. [Disposal Safety, Inc., Washington, DC (USA)

1990-12-31

Yucca Mountain is being studied to determine its suitability as a location for a high-level nuclear waste repository. Amter and Ross developed a model called TGIF (Topographic Induced Flow) to simulate gas flow under Yucca Mountain. The TGIF model differs significantly from previous gas flow models. It uses a governing equation that is based on the concept of freshwater head, thus avoiding the numerical problems associated with the near-cancellation of the forces due to gravity and the pressure gradient. Unlike most other models, dipping, layered media can be simulated. This paper describes a systematic sensitivity study that was designed to test several aspects of the TGIF model when used to simulate gas flow under Yucca Mountain. Values of three important inputs to the model were systematically varied to form a matrix of 80 runs. The matrix consisted of five values of permeability contrast between a bedded tuff layer and surrounding welded units (in all cases, bulk permeabilities were used to represent the combined effect of both fractures and matrix permeability), four temperature profiles representing different stages of repository cooldown, and four finite-difference grids.

The complex initial reluctivity, permeability and susceptibility spectra of magnetic materials

Science.gov (United States)

Hamilton, N. C.

2015-03-01

The HF complex permeability spectrum of a magnetic material is deduced from the measured impedance spectrum, which is then normalized to a series permeability spectrum. However, this series permeability spectrum has previously been shown to correspond to a parallel magnetic circuit, which is not appropriate. Some of the implications of this truth are examined. This electric/magnetic duality has frustrated efforts to interpret the shape of the complex magnetic permeability spectra of materials, and has hindered the application of impedance spectroscopy to magnetic materials. In the presence of magnetic loss, the relationship between the relative magnetic permeability and the magnetic susceptibility is called into question. The use of reluctivity spectra for expressing magnetic material properties is advocated. The relative loss factor, tanδm/μi is shown to be an approximation for the imaginary part of the reluctivity. A single relaxation model for the initial reluctivity spectra of magnetic materials is presented, and its principles are applied to measurements of a high permeability ferrite. The results are presented as contour plots of the spectra as a function of temperature.

The solubility-permeability interplay and oral drug formulation design: Two heads are better than one.

Science.gov (United States)

Dahan, Arik; Beig, Avital; Lindley, David; Miller, Jonathan M

2016-06-01

Poor aqueous solubility is a major challenge in today's biopharmaceutics. While solubility-enabling formulations can significantly increase the apparent solubility of the drug, the concomitant effect on the drug's apparent permeability has been largely overlooked. The mathematical equation to describe the membrane permeability of a drug comprises the membrane/aqueous partition coefficient, which in turn is dependent on the drug's apparent solubility in the GI milieu, suggesting that the solubility and the permeability are closely related, exhibit a certain interplay between them, and treating the one irrespectively of the other may be insufficient. In this article, an overview of this solubility-permeability interplay is provided, and the available data is analyzed in the context of the effort to maximize the overall drug exposure. Overall, depending on the type of solubility-permeability interplay, the permeability may decrease, remain unchanged, and even increase, in a way that may critically affect the formulation capability to improve the overall absorption. Therefore, an intelligent design of solubility-enabling formulation needs to consider both the solubility afforded by the formulation and the permeability in the new luminal environment resulting from the formulation. Copyright © 2016 Elsevier B.V. All rights reserved.

Permeability of gypsum samples dehydrated in air

Science.gov (United States)

Milsch, Harald; Priegnitz, Mike; Blöcher, Guido

2011-09-01

We report on changes in rock permeability induced by devolatilization reactions using gypsum as a reference analog material. Cylindrical samples of natural alabaster were dehydrated in air (dry) for up to 800 h at ambient pressure and temperatures between 378 and 423 K. Subsequently, the reaction kinetics, so induced changes in porosity, and the concurrent evolution of sample permeability were constrained. Weighing the heated samples in predefined time intervals yielded the reaction progress where the stoichiometric mass balance indicated an ultimate and complete dehydration to anhydrite regardless of temperature. Porosity showed to continuously increase with reaction progress from approximately 2% to 30%, whilst the initial bulk volume remained unchanged. Within these limits permeability significantly increased with porosity by almost three orders of magnitude from approximately 7 × 10-19 m2 to 3 × 10-16 m2. We show that - when mechanical and hydraulic feedbacks can be excluded - permeability, reaction progress, and porosity are related unequivocally.

The effect of different surface materials on runoff quality in permeable pavement systems.

Science.gov (United States)

Li, Haiyan; Li, Zhifei; Zhang, Xiaoran; Li, Zhuorong; Liu, Dongqing; Li, Tanghu; Zhang, Ziyang

2017-09-01

To investigate the effect of different permeable pavement surface materials on the removal of pollutants from urban storm-runoff, six commonly surface materials (porous asphalt, porous concrete, cement brick, ceramic brick, sand base brick, and shale brick) were selected in this study and the research was carried out by column experiments. Except the concentrations of total suspended solids (TSS), chemical oxygen demand (COD), ammonia nitrogen (NH 4 -N), nitrate nitrogen (NO 3 -N), total nitrogen (TN), and total phosphorus (TP) in the influent and effluent that were measured, the removal mechanism of pollutants was discussed further. The results indicate that the surface materials influence the removal efficiency of pollutants greatly and have different effects on certain pollutant. Furthermore, the physical interception and adsorption would be the main mechanism for the removal of pollutants from runoff. For example, for all surface materials, the average removal efficiency of TSS is nearly about 90.0% because of physical interception. Due to the amount of iron oxide, the removal efficiency of COD, NO 3 -N, and TN of shale brick was 88.2, 35.1, and 17.5%, respectively. NH 4 -N and TN can be easily removed by porous asphalt due to the high content of organic matter. By lacking of useful adsorption sites, all the surface materials had little effect on the removal of TP from runoff. This research could offer useful guidelines for the better design of permeable pavement system and promote the insight into the removal mechanism of pollutants in permeable pavement system. Graphical abstract Different types of materials for the different types of pollutants in the runoff purification capacity were significantly different, overall, shale brick and porous asphalt Shale bricks and porous asphalt have a better purification effect according to the six kinds of materials.

Permeability of Concrete with Recycled Concrete Aggregate and Pozzolanic Materials under Stress.

Science.gov (United States)

Wang, Hailong; Sun, Xiaoyan; Wang, Junjie; Monteiro, Paulo J M

2016-03-30

The research reported herein studied the permeability of concrete containing recycled-concrete aggregate (RA), superfine phosphorous slag (PHS), and ground granulated blast-furnace slag (GGBS) with and without stress. Test results showed that the chloride diffusion coefficient of RA concrete (RAC) without external loads decreased with time, and the permeability of RAC is much lower than that of the reference concrete due to the on-going hydration and the pozzolanic reaction provided by the PHS and GGBS additives in the RAC mixture. The permeability of chloride under flexural load is much more sensitive than that under compressive load due to the differences in porosity and cracking pattern. At low compressive stress levels, the permeability of chloride decreased by the closing of pores and microcracks within RAC specimens. However, in a relatively short time the chloride diffusion coefficient and the chloride content increased rapidly with the increase of compressive stress when it exceeded a threshold stress level of approximate 35% of the ultimate compressive strength. Under flexural stress, the chloride transport capability increased with the increase of stress level and time. At high compressive and flexural stress levels, creep had a significant effect on the permeability of chloride in the RAC specimens due to the damage from the nucleation and propagation of microcracks over time. It is apparent that mortar cracking has more of a significant effect on the chloride transport in concrete than cracking in the interfacial transition zone (ITZ).

Theory and test research on permeability of coal and rock body influenced by mining

Energy Technology Data Exchange (ETDEWEB)

Qing-xin Qi; Hong-yan Li; You-gang Wang; Zhi-gang Deng; Hang Lan; Yong-wei Peng; Chun-rui Li [China Coal Research Institute, Beijing (China)

2009-06-15

Stress distribution rules and deformation and failure properties of coal and rock bodies influenced by mining were analyzed. Experimental research on permeability of coal and rock samples under different loading conditions was finished in the laboratory. In-situ measurement of coal permeability influenced by actual mining was done as well. Theory analysis show that permeability varied with damage development of coal and rock under stress, and the influence of fissure on permeability was greatest. Laboratory results show that under different loading conditions permeability was different and it varied with stress, which indicated that permeability was directly related to the loading process. In-situ tests showed that permeability is related to abutment stress to some degree. The above results may be referenced to gas prevention and drainage. 11 refs., 6 figs., 1 tab.

Therapeutic benefits of enhancing permeability barrier for atopic eczema

Directory of Open Access Journals (Sweden)

George Man

2015-06-01

Full Text Available The regulatory role of epidermal permeability barrier function in cutaneous inflammation has been well appreciated. While barrier disruption induces cutaneous inflammation, improvement of permeability barrier function alleviates inflammation. Studies have demonstrated that improvement of epidermal permeability barrier function not only prevents the development of atopic eczema, but also delays the relapse of these diseases. Moreover, enhancing the epidermal permeability barrier also alleviates atopic eczema. Furthermore, co-applications of barrier enhancing products with glucocorticoids can increase the therapeutic efficacy and reduce the adverse effects of glucocorticoids in the treatment of atopic eczema. Therefore, utilization of permeability barrier enhancing products alone or in combination with glucocorticoids could be a valuable approach in the treatment of atopic eczema. In this review, we discuss the benefits of improving the epidermal permeability barrier in the management of atopic eczema.

Support vector regression to predict porosity and permeability: Effect of sample size

Science.gov (United States)

Al-Anazi, A. F.; Gates, I. D.

2012-02-01

Porosity and permeability are key petrophysical parameters obtained from laboratory core analysis. Cores, obtained from drilled wells, are often few in number for most oil and gas fields. Porosity and permeability correlations based on conventional techniques such as linear regression or neural networks trained with core and geophysical logs suffer poor generalization to wells with only geophysical logs. The generalization problem of correlation models often becomes pronounced when the training sample size is small. This is attributed to the underlying assumption that conventional techniques employing the empirical risk minimization (ERM) inductive principle converge asymptotically to the true risk values as the number of samples increases. In small sample size estimation problems, the available training samples must span the complexity of the parameter space so that the model is able both to match the available training samples reasonably well and to generalize to new data. This is achieved using the structural risk minimization (SRM) inductive principle by matching the capability of the model to the available training data. One method that uses SRM is support vector regression (SVR) network. In this research, the capability of SVR to predict porosity and permeability in a heterogeneous sandstone reservoir under the effect of small sample size is evaluated. Particularly, the impact of Vapnik's ɛ-insensitivity loss function and least-modulus loss function on generalization performance was empirically investigated. The results are compared to the multilayer perception (MLP) neural network, a widely used regression method, which operates under the ERM principle. The mean square error and correlation coefficients were used to measure the quality of predictions. The results demonstrate that SVR yields consistently better predictions of the porosity and permeability with small sample size than the MLP method. Also, the performance of SVR depends on both kernel function

Effect of drilling fluids on permeability of uranium sandstone. Report of Investigations/1984

International Nuclear Information System (INIS)

Ahlness, J.K.; Johnson, D.I.; Tweeton, D.R.

1984-01-01

The Bureau of Mines conducted laboratory and field experiments to determine the amount of permeability reduction in uranium sandstone after its exposure to different drilling fluids. Seven polymer and two bentonite fluids were laboratory-tested in their clean condition, and six polymer fluids were tested with simulated drill cuttings added. Sandstone cores cut from samples collected at an open pit uranium mine were the test medium. The clean fluid that resulted in the least permeability reduction was an hydroxyethyl cellulose polymer fluid. The greatest permeability reduction of the clean polymers came from a shale-inhibiting synthetic polymer. Six polymer fluids were tested with simulated drill cuttings added to represent field use. The least permeability reduction was obtained from a multi-polymer blend fluid. A field experiment was performed to compare how two polymer fluids affect formation permeability when used for drilling in situ uranium leaching wells

Modelling the effects of porous and semi-permeable layers on corrosion processes

International Nuclear Information System (INIS)

King, F.; Kolar, M.; Shoesmith, D.W.

1996-09-01

Porous and semi-permeable layers play a role in many corrosion processes. Porous layers may simply affect the rate of corrosion by affecting the rate of mass transport of reactants and products to and from the corroding surface. Semi-permeable layers can further affect the corrosion process by reacting with products and/or reactants. Reactions in semi-permeable layers include redox processes involving electron transfer, adsorption, ion-exchange and complexation reactions and precipitation/dissolution processes. Examples of porous and semi-permeable layers include non-reactive salt films, precipitate layers consisting of redox-active species in multiple oxidation states (e.g., Fe oxide films), clay and soil layers and biofilms. Examples of these various types of processes will be discussed and modelling techniques developed from studies for the disposal of high-level nuclear waste presented. (author). 48 refs., 1 tab., 12 figs

Permeability measuremens of brazilian Eucalyptus

Directory of Open Access Journals (Sweden)

Marcio Rogério da Silva

2010-09-01

Full Text Available The permeability of Brazilian Eucalyptus grandis and Eucalyptus citriodora wood was measured in a custom build gas analysis chamber in order to determine which species could be successfully treated with preservatives. Liquid permeability was tested using an emulsion of Neen oil and a control of distillated water. Air was used to test the gas phase permeability. For both Eucalyptus grandis and Eucalyptus citriodora, the longitudinal permeability of gas was shown to be about twice as great as the liquid phase permeability. No radial permeability was observed for either wood. The permeability of air and water through the sapwood of Eucalyptus grandis was greater than that through the sapwood of Eucalyptus citriodora. The permeability of neen oil preservative through the sapwood of Eucalyptus grandis was also greater than through the sapwood of E. Citradora, but the difference was not statistically significant. Scanning Electron Microscopy images showed that the distribution and obstruction in the vessels could be correlated with observed permeability properties. Irrespective of the causes of differences in permeability between the species, the fluid phase flux through the sapwood of both species was significant, indicating that both Eucalyptus grandis and Eucalyptus citriodora could be successfully treated with wood preservative.

A theoretical model for gas permeability in a composite membrane

International Nuclear Information System (INIS)

Serrano, D. A

2009-01-01

We present in this work an analytical expression for permeability in a two-layer composite membrane, which was derived assuming the same hypothesis as those of Adzumi model for permeability in a homogeneous membrane. Whereas in Adzumi model permeability shows a linear dependence on the mean pressure, our model for a composite membrane related permeability to pressure through a rather complex expression, which covers the whole range of flow, from molecular-Knudsen to viscous-Poiseuille regimes. The expression obtained for permeability contained information of membrane structural properties as pore size, porosity and thickness of each layer, as well as gas nature and operational conditions. Our two-layer-model expression turns into Adzumi formula when the structure of the layers approach to each other. [es

Effect of dissolved oxygen manipulation on diffusive emissions from NAPL-impacted low permeability soil layers.

Science.gov (United States)

Clifton, Lisa M; Dahlen, Paul R; Johnson, Paul C

2014-05-06

Aquifer physical model experiments were performed to investigate if diffusive emissions from nonaqueous phase liquid (NAPL)-impacted low-permeability layers into groundwater moving through adjacent NAPL-free high-permeability layers can be reduced by creating an aerobic biotreatment zone at the interface between the two, and if over time that leads to reduced emissions after treatment ceases. Experiments were performed in two 1.2-m long × 1.2-m high × 5.4 cm wide stainless steel tanks; each with a high-permeability sand layer overlying a low-permeability crushed granite layer containing a NAPL mixture of indane and benzene. Each tank was water-saturated with horizontal flow primarily through the sand layer. The influent water was initially deoxygenated and the emissions and concentration distributions were allowed to reach near-steady conditions. The influent dissolved oxygen (DO) level was increased stepwise to 6.5-8.5 mg/L and 17-20 mg/L, and then decreased back to deoxygenated conditions. Each condition was maintained for at least 45 days. Relative to the near-steady benzene emission at the initial deoxygenated condition, the emission was reduced by about 70% when the DO was 6.5-8.5 mg/L, 90% when the DO was 17-20 mg/L, and ultimately 60% when returning to low DO conditions. While the reductions were substantial during treatment, longer-term reductions after 120 d of elevated DO treatment, relative to an untreated condition predicted by theory, were low: 29% and 6% in Tank 1 and Tank 2, respectively. Results show a 1-2 month lag between the end of DO delivery and rebound to the final near-steady emissions level. This observation has implications for post-treatment performance monitoring sampling at field sites.

A relative permeability model to derive fractional-flow functions of water-alternating-gas and surfactant-alternating-gas foam core-floods

International Nuclear Information System (INIS)

Al-Mossawy, Mohammed Idrees; Demiral, Birol; Raja, D M Anwar

2013-01-01

Foam is used in enhanced oil recovery to improve the sweep efficiency by controlling the gas mobility. The surfactant-alternating-gas (SAG) foam process is used as an alternative to the water-alternating-gas (WAG) injection. In the WAG technique, the high mobility and the low density of the gas lead the gas to flow in channels through the high permeability zones of the reservoir and to rise to the top of the reservoir by gravity segregation. As a result, the sweep efficiency decreases and there will be more residual oil in the reservoir. The foam can trap the gas in liquid films and reduces the gas mobility. The fractional-flow method describes the physics of immiscible displacements in porous media. Finding the water fractional flow theoretically or experimentally as a function of the water saturation represents the heart of this method. The relative permeability function is the conventional way to derive the fractional-flow function. This study presents an improved relative permeability model to derive the fractional-flow functions for WAG and SAG foam core-floods. The SAG flow regimes are characterized into weak foam, strong foam without a shock front and strong foam with a shock front. (paper)

Thermally induced permeability reduction due to particle migration in sandstones: the effect of temperature on kaolinite mobilisation and aggregation

DEFF Research Database (Denmark)

Rosenbrand, Esther; Fabricius, Ida Lykke; Yuan, Hao

2012-01-01

The seasonal imbalance in supply and demand of renewable energy requires seasonal storage, which potentially may be achieved by hot water injection in geothermal aquifers to minimize heat loss by advection. A reduction of porosity and permeability is a risk of heating the rock above the in...... the interaction energy between quartz and kaolinite particles for different saturating fluids. The results are compared to the published data addressing the effect of temperature on permeability. This provides a qualitative explanation for the observed changes in permeability with temperature for the tests...

Effect of particle size distribution on permeability in the randomly packed porous media

Science.gov (United States)

Markicevic, Bojan

2017-11-01

An answer of how porous medium heterogeneity influences the medium permeability is still inconclusive, where both increase and decrease in the permeability value are reported. A numerical procedure is used to generate a randomly packed porous material consisting of spherical particles. Six different particle size distributions are used including mono-, bi- and three-disperse particles, as well as uniform, normal and log-normal particle size distribution with the maximum to minimum particle size ratio ranging from three to eight for different distributions. In all six cases, the average particle size is kept the same. For all media generated, the stochastic homogeneity is checked from distribution of three coordinates of particle centers, where uniform distribution of x-, y- and z- positions is found. The medium surface area remains essentially constant except for bi-modal distribution in which medium area decreases, while no changes in the porosity are observed (around 0.36). The fluid flow is solved in such domain, and after checking for the pressure axial linearity, the permeability is calculated from the Darcy law. The permeability comparison reveals that the permeability of the mono-disperse medium is smallest, and the permeability of all poly-disperse samples is less than ten percent higher. For bi-modal particles, the permeability is for a quarter higher compared to the other media which can be explained by volumetric contribution of larger particles and larger passages for fluid flow to take place.

Oral Supplementation with Bovine Colostrum Decreases Intestinal Permeability and Stool Concentrations of Zonulin in Athletes

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Maciej Hałasa

2017-04-01

Full Text Available Increased intestinal permeability has been implicated in various pathologies, has various causes, and can develop during vigorous athletic training. Colostrum bovinum is a natural supplement with a wide range of supposed positive health effects, including reduction of intestine permeability. We assessed influence of colostrum supplementation on intestinal permeability related parameters in a group of 16 athletes during peak training for competition. This double-blind placebo-controlled study compared supplementation for 20 days with 500 mg of colostrum bovinum or placebo (whey. Gut permeability status was assayed by differential absorption of lactulose and mannitol (L/M test and stool zonulin concentration. Baseline L/M tests found that six of the participants (75% in the colostrum group had increased intestinal permeability. After supplementation, the test values were within the normal range and were significantly lower than at baseline. The colostrum group Δ values produced by comparing the post-intervention and baseline results were also significantly lower than the placebo group Δ values. The differences in stool zonulin concentration were smaller than those in the L/M test, but were significant when the Δ values due to intervention were compared between the colostrum group and the placebo group. Colostrum bovinum supplementation was safe and effective in decreasing of intestinal permeability in this series of athletes at increased risk of its elevation.

Oral Supplementation with Bovine Colostrum Decreases Intestinal Permeability and Stool Concentrations of Zonulin in Athletes.

Science.gov (United States)

Hałasa, Maciej; Maciejewska, Dominika; Baśkiewicz-Hałasa, Magdalena; Machaliński, Bogusław; Safranow, Krzysztof; Stachowska, Ewa

2017-04-08

Increased intestinal permeability has been implicated in various pathologies, has various causes, and can develop during vigorous athletic training. Colostrum bovinum is a natural supplement with a wide range of supposed positive health effects, including reduction of intestine permeability. We assessed influence of colostrum supplementation on intestinal permeability related parameters in a group of 16 athletes during peak training for competition. This double-blind placebo-controlled study compared supplementation for 20 days with 500 mg of colostrum bovinum or placebo (whey). Gut permeability status was assayed by differential absorption of lactulose and mannitol (L/M test) and stool zonulin concentration. Baseline L/M tests found that six of the participants (75%) in the colostrum group had increased intestinal permeability. After supplementation, the test values were within the normal range and were significantly lower than at baseline. The colostrum group Δ values produced by comparing the post-intervention and baseline results were also significantly lower than the placebo group Δ values. The differences in stool zonulin concentration were smaller than those in the L/M test, but were significant when the Δ values due to intervention were compared between the colostrum group and the placebo group. Colostrum bovinum supplementation was safe and effective in decreasing of intestinal permeability in this series of athletes at increased risk of its elevation.

A drainage data-based calculation method for coalbed permeability

International Nuclear Information System (INIS)

Lai, Feng-peng; Li, Zhi-ping; Fu, Ying-kun; Yang, Zhi-hao

2013-01-01

This paper establishes a drainage data-based calculation method for coalbed permeability. The method combines material balance and production equations. We use a material balance equation to derive the average pressure of the coalbed in the production process. The dimensionless water production index is introduced into the production equation for the water production stage. In the subsequent stage, which uses both gas and water, the gas and water production ratio is introduced to eliminate the effect of flush-flow radius, skin factor, and other uncertain factors in the calculation of coalbed methane permeability. The relationship between permeability and surface cumulative liquid production can be described as a single-variable cubic equation by derivation. The trend shows that the permeability initially declines and then increases after ten wells in the southern Qinshui coalbed methane field. The results show an exponential relationship between permeability and cumulative water production. The relationship between permeability and cumulative gas production is represented by a linear curve and that between permeability and surface cumulative liquid production is represented by a cubic polynomial curve. The regression result of the permeability and surface cumulative liquid production agrees with the theoretical mathematical relationship. (paper)

Blood-brain barrier permeability and neuroprotective effects of three main alkaloids from the fruits of Euodia rutaecarpa with MDCK-pHaMDR cell monolayer and PC12 cell line.

Science.gov (United States)

Zhang, Yi-Nan; Yang, Yan-Fang; Yang, Xiu-Wei

2018-02-01

The fruits of Euodia rutaecarpa (Euodiae Fructus, EF), the widely used traditional Chinese medicine, have various central nervous system effects. Alkaloids following as evodiamine (EDM), rutaecarpine (RCP) and dehydroevodiamine (DEDM) are the major substances in EF. The MDCK-pHaMDR cell monolayer model was utilized as a blood-brain barrier (BBB) surrogate model to study their BBB permeability. The transport samples were analyzed by high performance liquid chromatography and the apparent permeability coefficients (P app ) were calculated. EDM and RCP showed high permeability through BBB by passive diffusion, while DEDM showed moderate permeability with efflux mechanism related to P-glycoprotein (P-gp). EDM and RCP could also reduce the efflux of DEDM probably by inhibiting P-gp. The neuroprotective effects of the three alkaloids were then studied on the PC12 cell line injured by 1-methyl-4-phenylpyridinium ion (MPP + ) or hydrogen peroxide (H 2 O 2 ). EDM could significantly reduce MPP + or H 2 O 2 -induced cell injury dose-dependently. RCP could increase the cell viability in MPP + treated group while DEDM showed a protective effect against H 2 O 2 injury. This study predicted the permeability of EDM, RCP and DEDM through BBB and discovered the neuroprotective substance basis of EF as a potential encephalopathy drug. Copyright © 2017 Elsevier Masson SAS. All rights reserved.

Hybrid biofilm-membrane bioreactor (Bf-MBR) for minimization of bulk liquid-phase organic substances and its positive effect on membrane permeability.

Science.gov (United States)

Sun, F Y; Li, P; Li, J; Li, H J; Ou, Q M; Sun, T T; Dong, Z J

2015-12-01

Four biofilm membrane bioreactors (Bf-MBRs) with various fixed carrier volumes (C:M) were operated in parallel to investigate the effect of attached-growth mode biomass involvement to the change of liquid-phase organics characteristics and membrane permeability, by comparing with conventional MBR. The experiments displayed that C:M and co-existence of biofilm with suspended solids in Bf-MBRs resulted in slight difference in pollutants removal effectiveness, and in rather distinct biomass properties and bacterial activities. The membrane permeability and specific resistance of bulk suspension of Bf-MBRs related closely with the liquid-phase organic substance, including soluble microbial products (SMP) and biopolymer cluster (BPC). Compared with conventional MBR, Bf-MBR with proper C:M had a low total biomass content and food-chain, where biofilm formation and its dominance affected liquid-phase organics, especially through reducing their content and minimizing strongly and weakly hydrophobic components with small molecular weight, and thus to mitigate membrane fouling significantly. Copyright © 2015 Elsevier Ltd. All rights reserved.

Effects of insulin combined with idebenone on blood-brain barrier permeability in diabetic rats.

Science.gov (United States)

Sun, Yan-Na; Liu, Li-Bo; Xue, Yi-Xue; Wang, Ping

2015-04-01

This study investigates the effect of insulin combined with idebenone on blood-brain barrier (BBB) permeability in experimental streptozotocin-induced diabetic rats as well as the underlying mechanisms. With a diabetic rat model, we show that insulin and idebenone normalize body weight and water intake and restore BBB permeability and that their combination displays a synergistic effect. The results from transmission electron microscopy show that the combination of insulin and idebenone significantly closed the tight junction (TJ) in diabetic rats. The results from Western blotting in diabetic rats show that the upregulation of TJ-associated proteins occludin, and zonula occludens (ZO)-1 caused by the combination of insulin and idebenone is more remarkable than that with either agent alone. In addition, the activations of reactive oxygen species (ROS) and advanced glycation end products (AGEs) and the expression levels of receptors for advanced glycation end-products (RAGE) and nuclear factor-κB (NF-κB) were significantly decreased after treatment with insulin and idebenone in diabetic rats. These results suggest that the combination of insulin and idebenone could decrease the BBB permeability in diabetic rats by upregulating the expression of occludin, claudin-5, and ZO-1 and that the ROS/AGE/RAGE/NF-κB signal pathway might be involved in the process. © 2014 Wiley Periodicals, Inc.

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

Science.gov (United States)

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

2018-09-01

Road permeability to animal movements depends among several factors on structures which, integrated in the road design, operate as safe conducts to mitigate vehicle collision and barrier effects. There is abundant evidence that wildlife makes use of such structures as safe passages to cross roads. We analyzed the spatial relationship between road drainage elements (N = 253; mostly culverts) as potential faunal underpasses, and mortality due to vehicle collisions in two seasons and on four relatively low-traffic roads (roads, identifying and characterizing all potential underpasses. Overall frequencies of casualties and spatial distribution were highly variable both within and among these roads. We obtained an estimation of potential permeability for the different roads. We detected, located and described a wide supply and a very variable pattern of drainage culverts and other underpasses, with differences among roads in passage attributes potentially affecting permeability for wildlife, such as spatial arrangement, number, density (frequency or concentration of passages) and dimensions. We used Mantel tests to assess spatial congruence of passages and road-killed animals. We applied generalized linear mixed models fitted by maximum likelihood through Akaike Information Criterion to explain the variation in the distance of the 238 casualties to the nearest underpasses, with road transect and season as random factors, and traffic intensity, speed and vertebrate class as fixed effects. Both road-killed animals and underpass distribution followed aggregated patterns, and casualties were not significantly related to underpasses along any of the 4 roads. There were no differences in distance of casualties to the nearest underpass for the three vertebrate classes. Although existing underpasses were abundant, we could not correlate potential permeability with reduced mortality along these roads, and other factors potentially affecting roadkill aggregations should be

Breaking down the barriers: the gut microbiome, intestinal permeability and stress-related psychiatric disorders

Science.gov (United States)

Kelly, John R.; Kennedy, Paul J.; Cryan, John F.; Dinan, Timothy G.; Clarke, Gerard; Hyland, Niall P.

2015-01-01

The emerging links between our gut microbiome and the central nervous system (CNS) are regarded as a paradigm shift in neuroscience with possible implications for not only understanding the pathophysiology of stress-related psychiatric disorders, but also their treatment. Thus the gut microbiome and its influence on host barrier function is positioned to be a critical node within the brain-gut axis. Mounting preclinical evidence broadly suggests that the gut microbiota can modulate brain development, function and behavior by immune, endocrine and neural pathways of the brain-gut-microbiota axis. Detailed mechanistic insights explaining these specific interactions are currently underdeveloped. However, the concept that a “leaky gut” may facilitate communication between the microbiota and these key signaling pathways has gained traction. Deficits in intestinal permeability may underpin the chronic low-grade inflammation observed in disorders such as depression and the gut microbiome plays a critical role in regulating intestinal permeability. In this review we will discuss the possible role played by the gut microbiota in maintaining intestinal barrier function and the CNS consequences when it becomes disrupted. We will draw on both clinical and preclinical evidence to support this concept as well as the key features of the gut microbiota which are necessary for normal intestinal barrier function. PMID:26528128

Effect of persistent high intraocular pressure on microstructure and hydraulic permeability of trabecular meshwork

International Nuclear Information System (INIS)

Mei Xi; Ren Lin; Xu Qiang; Liu Zhi-Cheng; Zheng Wei

2015-01-01

As the aqueous humor leaves the eye, it first passes through the trabecular meshwork (TM). Increased flow resistance in this region causes elevation of intraocular pressure (IOP), which leads to the occurrence of glaucoma. To quantitatively evaluate the effect of high IOP on the configuration and hydraulic permeability of the TM, second harmonic generation (SHG) microscopy was used to image the microstructures of the TM and adjacent tissues in control (normal) and high IOP conditions. Enucleated rabbit eyes were perfused at a pressure of 60 mmHg to achieve the high IOP. Through the anterior chamber of the eye, in situ images were obtained from different depths beneath the surface of the TM. Porosity and specific surface area of the TM in control and high IOP conditions were then calculated to estimate the effect of the high pressure on the permeability of tissue in different depths. We further photographed the histological sections of the TM and compared the in situ images. The following results were obtained in the control condition, where the region of depth was less than 55 μm with crossed branching beams and large pores in the superficial TM. The deeper meshwork is a silk-like tissue with abundant fluorescence separating the small size of pores. The total thickness of pathway tissues composed of TM and juxtacanalicular (JCT) is more than 100 μm. After putting a high pressure on the inner wall of the eye, the TM region progressively collapses and decreases to be less than 40 μm. Fibers of the TM became dense, and the porosity at 34 μm in the high IOP condition is comparable to that at 105 μm in the control condition. As a consequent result, the permeability of the superficial TM decreases rapidly from 120 μm 2 to 49.6 μm 2 and that of deeper TM decreases from 1.66 μm 2 to 0.57 μm 2 . Heterogeneity reflected by descent in permeability reduces from 12.4 μm of the control condition to 3.74 μm of the high IOP condition. The persistently high IOP makes the

Evolution of permeability in diatomaceous rocks mediated by pressure solution

International Nuclear Information System (INIS)

Yasuhara, Hideaki; Kinoshita, Naoki; Kurikami, Hiroshi; Kishida, Kiyoshi

2007-01-01

A conceptual model is presented to follow the evolution of permeability in diatomaceous rocks mediated by pressure solution. The progress of compaction and the evolution of permeability may be followed with time. Specifically, the main minerals of diatomaceous rocks that are quartz, cristobalite, and amorphous silica, are focused to examine differences of the permeability evolutions among them at effective stresses of 5, and 10 MPa, and temperatures of 20 and 90degC. The rates and magnitudes of permeability reduction increase with increase of the dissolution rate constants. Ultimate permeabilities reduce to the order of 90% at the completion of dissolution-mediated compaction. (author)

Study on Surface Permeability of Concrete under Immersion.

Science.gov (United States)

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

2014-01-28

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

Acute effects of carprofen and meloxicam on canine gastrointestinal permeability and mucosal absorptive capacity.

Science.gov (United States)

Craven, Melanie; Chandler, Marge L; Steiner, Jörg M; Farhadi, Ashkan; Welsh, Elizabeth; Pratschke, Kathryn; Shaw, Darren J; Williams, David A

2007-01-01

Nonsteroidal anti-inflammatory drugs (NSAIDs) are frequently prescribed to dogs for their analgesic, antipyretic, and anti-inflammatory properties. Their beneficial actions can be offset by gastrointestinal (GI) toxicosis. Endoscopy has traditionally been employed to detect GI lesions, but alterations in GI permeability precede the development of mucosal damage. Carprofen and meloxicam alter GI permeability and mucosal absorptive capacity of dogs. Twenty adult dogs treated with an NSAID for >7 days were evaluated by permeability tests while receiving either carprofen (10 dogs) or meloxicam (10 dogs). Prospective, longitudinal observational study. A 6-sugar permeability test (sucrose, lactulose, rhamnose, 3-O-methyl-D-glucose, D-xylose, and sucralose) was performed on the day before NSAID treatment, and after 3 and 8 days of treatment. There were no significant differences in the urinary recovery ratios of lactulose: rhamnose, D-xylose: 3-O-methyl-D-glucose, or sucralose recovery within either group at any time during the study. Sucrose permeability in the meloxicam group did not alter significantly over time. However, sucrose permeability in the carprofen group decreased significantly by day 3 (P = .049) and increased again by day 8 (P = .049), to a level that was not significantly different to permeability before treatment (P = .695). The absence of increased GI permeability and diminished mucosal absorptive capacity in this group of dogs does not support the development of acute GI toxicosis during treatment with either meloxicam or carprofen.

A Systematic Procedure to Describe Shale Gas Permeability Evolution during the Production Process

Science.gov (United States)

Jia, B.; Tsau, J. S.; Barati, R.

2017-12-01

Gas flow behavior in shales is complex due to the multi-physics nature of the process. Pore size reduces as the in-situ stress increases during the production process, which will reduce intrinsic permeability of the porous media. Slip flow/pore diffusion enhances gas apparent permeability, especially under low reservoir pressures. Adsorption not only increases original gas in place but also influences gas flow behavior because of the adsorption layer. Surface diffusion between free gas and adsorption phase enhances gas permeability. Pore size reduction and the adsorption layer both have complex impacts on gas apparent permeability and non-Darcy flow might be a major component in nanopores. Previously published literature is generally incomplete in terms of coupling of all these four physics with fluid flow during gas production. This work proposes a methodology to simultaneously take them into account to describe a permeability evolution process. Our results show that to fully describe shale gas permeability evolution during gas production, three sets of experimental data are needed initially: 1) intrinsic permeability under different in-situ stress, 2) adsorption isotherm under reservoir conditions and 3) surface diffusivity measurement by the pulse-decay method. Geomechanical effects, slip flow/pore diffusion, adsorption layer and surface diffusion all play roles affecting gas permeability. Neglecting any of them might lead to misleading results. The increasing in-situ stress during shale gas production is unfavorable to shale gas flow process. Slip flow/pore diffusion is important for gas permeability under low pressures in the tight porous media. They might overwhelm the geomechanical effect and enhance gas permeability at low pressures. Adsorption layer reduces the gas permeability by reducing the effective pore size, but the effect is limited. Surface diffusion increases gas permeability more under lower pressures. The total gas apparent permeability might

Effective diffusion coefficients of DNAPL waste components in saturated low permeability soil materials

Science.gov (United States)

Ayral-Cinar, Derya; Demond, Avery H.

2017-12-01

Diffusion is regarded as the dominant transport mechanism into and out of low permeable subsurface lenses and layers in the subsurface. But, some reports of mass storage in such zones are higher than what might be attributable to diffusion, based on estimated diffusion coefficients. Despite the importance of diffusion to efforts to estimate the quantity of residual contamination in the subsurface, relatively few studies present measured diffusion coefficients of organic solutes in saturated low permeability soils. This study reports the diffusion coefficients of a trichloroethylene (TCE), and an anionic surfactant, Aerosol OT (AOT), in water-saturated silt and a silt-montmorillonite (25:75) mixture, obtained using steady-state experiments. The relative diffusivity ranged from 0.11 to 0.17 for all three compounds for the silt and the silt-clay mixture that was allowed to expand. In the case in which the swelling was constrained, the relative diffusivity was about 0.07. In addition, the relative diffusivity of 13C-labeled TCE through a water saturated silt-clay mixture that had contacted a field dense non-aqueous phase liquid (DNAPL) for 18 months was measured and equaled 0.001. These experimental results were compared with the estimates generated using common correlations, and it was found that, in all cases, the measured diffusion coefficients were significantly lower than the estimated. Thus, the discrepancy between mass accumulations observed in the field and the mass storage that can attributable to diffusion may be greater than previously believed.

A new water permeability measurement method for unsaturated tight materials using saline solutions

International Nuclear Information System (INIS)

Malinsky, Laurent; Talandier, Jean

2012-01-01

Document available in extended abstract form only. Relative water permeability of material in a radioactive waste disposal is a key parameter to simulate and predict saturation state evolution. In this paper we present a new measurement method and the results obtained for Callovo-Oxfordian (Cox) clay-stone, host rock of the underground Andra laboratory at Bure (Meuse/Haute-Marne). Relative water permeability of such a low permeability rock as Cox clay-stone has been measured up to now by an indirect method. It consists in submitting a rock sample to successive relative humidity steps imposed by saline solutions. The transient mass variation during each step and the mass at hydric equilibrium are interpreted generally by using an inverse analysis method. The water relative permeability function of water saturation is derived from water diffusion coefficient evolution and water retention curve. The proposed new method consists in directly measuring the water flux across a flat cylindrical submitted to a relative humidity gradient. Two special cells have been developed. The tightness of the lateral sample surface is insured by crushing a polyurethane ring surrounding the sample set in an aluminium device placed over a Plexiglas vessel filled with a saline solution. One of the cells is designed to allow humidity measurement in the cell. These cells can also be used to measure the relative humidity produced by a saline solution or by an unsaturated material. During a permeability measurement, the cell with the sample to be tested is continuously weighted in a Plexiglas box in which a saline solution imposes a different relative humidity at the upper sample face. The experimental set-up is shown on Figure 1. The mean permeability of the sample is proportional to the rate of mass variation when steady state is reached. The result of one test is shown on Figure 2(a). Twenty four permeability measurements have been performed on four argillite samples of 15 mm in height and

Predicting permeability and electrical conductivity of sedimentary rocks from microgeometry

International Nuclear Information System (INIS)

Schlueter, E.M.; Cook, N.G.W.

1991-02-01

The determination of hydrologic parameters that characterize fluid flow through rock masses on a large scale (e.g., hydraulic conductivity, capillary pressure, and relative permeability) is crucial to activities such as the planning and control of enhanced oil recovery operations, and the design of nuclear waste repositories. Hydraulic permeability and electrical conductivity of sedimentary rocks are predicted from the microscopic geometry of the pore space. The cross-sectional areas and perimeters of the individual pores are estimated from two-dimensional scanning electron micrographs of rock sections. The hydraulic and electrical conductivities of the individual pores are determined from these geometrical parameters, using Darcy's law and Ohm's law. Account is taken of the fact that the cross-sections are randomly oriented with respect to the channel axes, and for possible variation of cross-sectional area along the length of the pores. The effective medium theory from solid-state physics is then used to determine an effective average conductance of each pore. Finally, the pores are assumed to be arranged on a cubic lattice, which allows the calculation of overall macroscopic values for the permeability and the electrical conductivity. Preliminary results using Berea, Boise, Massilon and Saint-Gilles sandstones show reasonably close agreement between the predicted and measured transport properties. 12 refs., 5 figs., 1 tab

Field-scale forward and back diffusion through low-permeability zones

Science.gov (United States)

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

2017-07-01

Understanding the effects of back diffusion of groundwater contaminants from low-permeability zones to aquifers is critical to making site management decisions related to remedial actions. Here, we combine aquifer and aquitard data to develop recommended site characterization strategies using a three-stage classification of plume life cycle based on the solute origins: aquifer source zone dissolution, source zone dissolution combined with back diffusion from an aquitard, and only back diffusion. We use measured aquitard concentration profile data from three field sites to identify signature shapes that are characteristic of these three stages. We find good fits to the measured data with analytical solutions that include the effects of advection and forward and back diffusion through low-permeability zones, and linearly and exponentially decreasing flux resulting from source dissolution in the aquifer. Aquifer contaminant time series data at monitoring wells from a mature site were well described using analytical solutions representing the combined case of source zone and back diffusion, while data from a site where the source had been isolated were well described solely by back diffusion. The modeling approach presented in this study is designed to enable site managers to implement appropriate remediation technologies at a proper timing for high- and low-permeability zones, considering estimated plume life cycle.

Silver nanoparticles interact with the cell membrane and increase endothelial permeability by promoting VE-cadherin internalization

Energy Technology Data Exchange (ETDEWEB)

Sun, Xia; Shi, Junpeng; Zou, Xiaoyan; Wang, Chengcheng; Yang, Yi; Zhang, Hongwu, E-mail: hwzhang@iue.ac.cn

2016-11-05

Highlights: • Short-term exposure to AgNPs at low doses induces increase HUVECs monolayer permeability. • AgNPs interact with the cell membrane and increase endothelial permeability by promoting VE-Cadherin internalization. • Particle effect is a major factor leading to endothelial dysfunction. - Abstract: The toxicological risks of silver nanoparticles (AgNPs) have attracted widespread attention, and many studies have been published that have contributed to understanding AgNPs-induced toxicity. However, little attention has been paid to the low-dose effects of AgNPs and the related toxicological mechanism is still unclear. Here, we show that short-term exposure to AgNPs at low doses induces a substantial increase in human umbilical vein endothelial cells (HUVECs) monolayer permeability, whereas Ag ions at low doses do not induce an observable increase in monolayer permeability. This effect is independent of oxidative stress and apoptosis. Scanning electron microscopy confirms that AgNPs adhere to the cell membrane after 1 h exposure. Furthermore, adhesion of AgNPs to the cell membrane can trigger vascular endothelial (VE)-cadherin phosphorylation at Y658 followed by VE-cadherin internalization, which lead to the increase in endothelial monolayer permeability. Our data show that surface interactions of AgNPs with the cell membrane, in other words, the particle effect, is a major factor leading to endothelial dysfunction following low-dose and short-term exposure. Our findings will contribute to understanding the health effects and the toxicological mechanisms of AgNPs.

Mathematical Model to Predict the Permeability of Water Transport in Concrete Structure

OpenAIRE

Solomon Ndubuisi Eluozo

2013-01-01

Mathematical model to predict the permeability of water transport in concrete has been established, the model is to monitor the rate of water transport in concrete structure. The process of this water transport is based on the constituent in the mixture of concrete. Permeability established a relation on the influence of the micropores on the constituent that made of concrete, the method of concrete placement determine the rate of permeability deposition in concrete structure, permeability es...

Cell permeability beyond the rule of 5.

Science.gov (United States)

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. Copyright © 2016 Elsevier B.V. All rights reserved.

Persistence of aquatic insects across managed landscapes: effects of landscape permeability on re-colonization and population recovery.

Directory of Open Access Journals (Sweden)

Nika Galic

Full Text Available Human practices in managed landscapes may often adversely affect aquatic biota, such as aquatic insects. Dispersal is often the limiting factor for successful re-colonization and recovery of stressed habitats. Therefore, in this study, we evaluated the effects of landscape permeability, assuming a combination of riparian vegetation (edge permeability and other vegetation (landscape matrix permeability, and distance between waterbodies on the colonization and recovery potential of weakly flying insects. For this purpose, we developed two models, a movement and a population model of the non-biting midge, Chironomus riparius, an aquatic insect with weak flying abilities. With the movement model we predicted the outcome of dispersal in a landscape with several linear water bodies (ditches under different assumptions regarding landscape-dependent movement. Output from the movement model constituted the probabilities of encountering another ditch and of staying in the natal ditch or perishing in the landscape matrix, and was used in the second model. With this individual-based model of midge populations, we assessed the implications for population persistence and for recovery potential after an extreme stress event. We showed that a combination of landscape attributes from the movement model determines the fate of dispersing individuals and, once extrapolated to the population level, has a big impact on the persistence and recovery of populations. Population persistence benefited from low edge permeability as it reduced the dispersal mortality which was the main factor determining population persistence and viability. However, population recovery benefited from higher edge permeability, but this was conditional on the low effective distance that ensured fewer losses in the landscape matrix. We discuss these findings with respect to possible landscape management scenarios.

Effects of hepatic ischemia-reperfusion injury on the blood-brain barrier permeability to [14C] and [13C]sucrose.

Science.gov (United States)

Miah, Mohammad K; Bickel, Ulrich; Mehvar, Reza

2017-12-01

Hepatic encephalopathy that is associated with severe liver failure may compromise the blood-brain barrier (BBB) integrity. However, the effects of less severe liver diseases, in the absence of overt encephalopathy, on the BBB are not well understood. The goal of the current study was to investigate the effects of hepatic ischemia-reperfusion (IR) injury on the BBB tight junction permeability to small, hydrophilic molecules using the widely used [ 14 C]sucrose and recently-proposed alternative [ 13 C]sucrose as markers. Rats were subjected to 20 min of hepatic ischemia or sham surgery, followed by 8 h of reperfusion before administration of a single bolus dose of [ 14 C] or [ 13 C]sucrose and collection of serial (0-30 min) blood and plasma and terminal brain samples. The concentrations of [ 14 C] and [ 13 C]sucrose in the samples were determined by measurement of total radioactivity (nonspecific) and LC-MS/MS (specific), respectively. IR injury significantly increased the blood, plasma, and brain concentrations of both [ 14 C] and [ 13 C]sucrose. However, when the brain concentrations were corrected for their respective area under the blood concentration-time curve, only [ 14 C]sucrose showed significantly higher (30%) BBB permeability values in the IR animals. Because [ 13 C]sucrose is a more specific BBB permeability marker, these data indicate that our animal model of hepatic IR injury does not affect the BBB tight junction permeability to small, hydrophilic molecules. Methodological differences among studies of the effects of liver diseases on the BBB permeability may confound the conclusions of such studies.

Perovskite-related oxide materials for oxygen-permeable electrochemical membrans

OpenAIRE

Naumovich, E. N.; Yaremchenko, A. A.; Viskup, A. P.; Kharton, V. V.

2003-01-01

This brief review is focused on the studies of mixed ionic-electronic conductors on the basis of lanthanum gallate doped with transition metal cations in the В sublattice. The substitution of gallium with iron, cobalt or nickel results in greater electronic conductivity, simultaneously keeping high level of the oxy-gen ionic transport. In particular, La0 90Sr0 10Ga0 65Ni0 20Mg0 1503d perovskite exhib-its attractive oxygen permeability, which is quite similar to that of La2Ni04- and (...

Experimental Study of Bacterial Penetration into Chalk Rock: Mechanisms and Effect on Permeability

DEFF Research Database (Denmark)

Halim, Amalia Yunita; Shapiro, Alexander; Eliasson Lantz, Anna

2014-01-01

Bacterial selective plugging is one of the mechanisms through which microorganisms can be applied for enhanced oil recovery, as bacteria can plug the water-swept zones of a reservoir, thus altering the flow paths and improving sweep efficiency. However, complete understanding of the penetration...... behavior of bacteria is lacking, especially in chalk formations where characteristic pore throat sizes are comparable with the sizes of bacterial cells. In this study, two bacterial strains, Bacillus licheniformis 421 (spore-forming) and Pseudomonas putida K12 (non-spore forming) were used to investigate...... the penetration of bacteria into chalk and its effect on permeability reduction. The core plugs were produced from Stevns Klint outcrop with low permeability (2–4 mD) and with pore sizes comparable to bacterial sizes. Both types of bacteria were able to penetrate and to be transported through the cores to some...

Investigation clogging dynamic of permeable pavement systems using embedded sensors

Science.gov (United States)

Razzaghmanesh, Mostafa; Borst, Michael

2018-02-01

Permeable pavement is a stormwater control measure commonly selected in both new and retrofit applications. However, there is limited information about the clogging mechanism of these systems that effects the infiltration. A permeable pavement site located at the Seitz Elementary School, on Fort Riley, Kansas was selected for this study. An 80-space parking lot was built behind the school as part of an EPA collaboration with the U.S. Army. The parking lot design includes a permeable interlocking concrete pavement section along the downgradient edge. This study monitored the clogging progress of the pavement section using twelve water content reflectometers and three buried tipping bucket rain gauges. This clogging dynamic investigation was divided into three stages namely pre-clogged, transitional, and clogged. Recorded initial relative water content of all three stages were significantly and negatively correlated to antecedent dry weather periods with stronger correlations during clogged conditions. The peak relative water content correlation with peak rainfall 10-min intensity was significant for the water content reflectometers located on the western edge away from the eastern edge; this correlation was strongest during transition stage. Once clogged, rainfall measurements no longer correlated with the buried tipping bucket rain gauges. Both water content reflectometers and buried tipping bucket rain gauges showed the progress of surface clogging. For every 6 mm of rain, clogging advanced 1 mm across the surface. The results generally support the hypothesis that the clogging progresses from the upgradient to the downgradient edge. The magnitude of the contributing drainage area and rainfall characteristics are effective factors on rate and progression of clogging.

Intestinal permeability study of minoxidil: assessment of minoxidil as a high permeability reference drug for biopharmaceutics classification.

Science.gov (United States)

Ozawa, Makoto; Tsume, Yasuhiro; Zur, Moran; Dahan, Arik; Amidon, Gordon L

2015-01-05

The purpose of this study was to evaluate minoxidil as a high permeability reference drug for Biopharmaceutics Classification System (BCS). The permeability of minoxidil was determined in in situ intestinal perfusion studies in rodents and permeability studies across Caco-2 cell monolayers. The permeability of minoxidil was compared with that of metoprolol, an FDA reference drug for BCS classification. In rat perfusion studies, the permeability of minoxidil was somewhat higher than that of metoprolol in the jejunum, while minoxidil showed lower permeability than metoprolol in the ileum. The permeability of minoxidil was independent of intestinal segment, while the permeability of metoprolol was region-dependent. Similarly, in mouse perfusion study, the jejunal permeability of minoxidil was 2.5-fold higher than that of metoprolol. Minoxidil and metoprolol showed similar permeability in Caco-2 study at apical pH of 6.5 and basolateral pH of 7.4. The permeability of minoxidil was independent of pH, while metoprolol showed pH-dependent transport in Caco-2 study. Minoxidil exhibited similar permeability in the absorptive direction (AP-BL) in comparison with secretory direction (BL-AP), while metoprolol had higher efflux ratio (ER > 2) at apical pH of 6.5 and basolateral pH of 7.4. No concentration-dependent transport was observed for either minoxidil or metoprolol transport in Caco-2 study. Verapamil did not alter the transport of either compounds across Caco-2 cell monolayers. The permeability of minoxidil was independent of both pH and intestinal segment in intestinal perfusion studies and Caco-2 studies. Caco-2 studies also showed no involvement of carrier mediated transport in the absorption process of minoxidil. These results suggest that minoxidil may be an acceptable reference drug for BCS high permeability classification. However, minoxidil exhibited higher jejunal permeability than metoprolol and thus to use minoxidil as a reference drug would raise the

Gliadin, zonulin and gut permeability: Effects on celiac and non-celiac intestinal mucosa and intestinal cell lines.

Science.gov (United States)

Drago, Sandro; El Asmar, Ramzi; Di Pierro, Mariarosaria; Grazia Clemente, Maria; Tripathi, Amit; Sapone, Anna; Thakar, Manjusha; Iacono, Giuseppe; Carroccio, Antonio; D'Agate, Cinzia; Not, Tarcisio; Zampini, Lucia; Catassi, Carlo; Fasano, Alessio

2006-04-01

Little is known about the interaction of gliadin with intestinal epithelial cells and the mechanism(s) through which gliadin crosses the intestinal epithelial barrier. We investigated whether gliadin has any immediate effect on zonulin release and signaling. Both ex vivo human small intestines and intestinal cell monolayers were exposed to gliadin, and zonulin release and changes in paracellular permeability were monitored in the presence and absence of zonulin antagonism. Zonulin binding, cytoskeletal rearrangement, and zonula occludens-1 (ZO-1) redistribution were evaluated by immunofluorescence microscopy. Tight junction occludin and ZO-1 gene expression was evaluated by real-time polymerase chain reaction (PCR). When exposed to gliadin, zonulin receptor-positive IEC6 and Caco2 cells released zonulin in the cell medium with subsequent zonulin binding to the cell surface, rearrangement of the cell cytoskeleton, loss of occludin-ZO1 protein-protein interaction, and increased monolayer permeability. Pretreatment with the zonulin antagonist FZI/0 blocked these changes without affecting zonulin release. When exposed to luminal gliadin, intestinal biopsies from celiac patients in remission expressed a sustained luminal zonulin release and increase in intestinal permeability that was blocked by FZI/0 pretreatment. Conversely, biopsies from non-celiac patients demonstrated a limited, transient zonulin release which was paralleled by an increase in intestinal permeability that never reached the level of permeability seen in celiac disease (CD) tissues. Chronic gliadin exposure caused down-regulation of both ZO-1 and occludin gene expression. Based on our results, we concluded that gliadin activates zonulin signaling irrespective of the genetic expression of autoimmunity, leading to increased intestinal permeability to macromolecules.

Polymeric membrane materials: new aspects of empirical approaches to prediction of gas permeability parameters in relation to permanent gases, linear lower hydrocarbons and some toxic gases.

Science.gov (United States)

Malykh, O V; Golub, A Yu; Teplyakov, V V

2011-05-11

Membrane gas separation technologies (air separation, hydrogen recovery from dehydrogenation processes, etc.) use traditionally the glassy polymer membranes with dominating permeability of "small" gas molecules. For this purposes the membranes based on the low free volume glassy polymers (e.g., polysulfone, tetrabromopolycarbonate and polyimides) are used. On the other hand, an application of membrane methods for VOCs and some toxic gas recovery from air, separation of the lower hydrocarbons containing mixtures (in petrochemistry and oil refining) needs the membranes with preferable penetration of components with relatively larger molecular sizes. In general, this kind of permeability is characterized for rubbers and for the high free volume glassy polymers. Data files accumulated (more than 1500 polymeric materials) represent the region of parameters "inside" of these "boundaries." Two main approaches to the prediction of gas permeability of polymers are considered in this paper: (1) the statistical treatment of published transport parameters of polymers and (2) the prediction using model of ≪diffusion jump≫ with consideration of the key properties of the diffusing molecule and polymeric matrix. In the frames of (1) the paper presents N-dimensional methods of the gas permeability estimation of polymers using the correlations "selectivity/permeability." It is found that the optimal accuracy of prediction is provided at n=4. In the frames of the solution-diffusion mechanism (2) the key properties include the effective molecular cross-section of penetrating species to be responsible for molecular transportation in polymeric matrix and the well known force constant (ε/k)(eff i) of {6-12} potential for gas-gas interaction. Set of corrected effective molecular cross-section of penetrant including noble gases (He, Ne, Ar, Kr, Xe), permanent gases (H(2), O(2), N(2), CO), ballast and toxic gases (CO(2), NO(,) NO(2), SO(2), H(2)S) and linear lower hydrocarbons (CH(4

Hybrid green permeable pave with hexagonal modular pavement systems

International Nuclear Information System (INIS)

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

2013-01-01

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.

Compressible fluid flow through rocks of variable permeability

International Nuclear Information System (INIS)

Lin, W.

1977-01-01

The effectiveness of course-grained igneous rocks as shelters for burying radioactive waste can be assessed by determining the rock permeabilities at their in situ pressures and stresses. Analytical and numerical methods were used to solve differential equations of one-dimensional fluid flow through rocks with permeabilities from 10 4 to 1 nD. In these calculations, upstream and downstream reservoir volumes of 5, 50, and 500 cm 3 were used. The optimal size combinations of the two reservoirs were determined for measurements of permeability, stress, strain, acoustic velocity, and electrical conductivity on low-porosity, coarse-grained igneous rocks

2D and 3D imaging resolution trade-offs in quantifying pore throats for prediction of permeability

Energy Technology Data Exchange (ETDEWEB)

Beckingham, Lauren E.; Peters, Catherine A.; Um, Wooyong; Jones, Keith W.; Lindquist, W.Brent

2013-09-03

Although the impact of subsurface geochemical reactions on porosity is relatively well understood, changes in permeability remain difficult to estimate. In this work, pore-network modeling was used to predict permeability based on pore- and pore-throat size distributions determined from analysis of 2D scanning electron microscopy (SEM) images of thin sections and 3D X-ray computed microtomography (CMT) data. The analyzed specimens were a Viking sandstone sample from the Alberta sedimentary basin and an experimental column of reacted Hanford sediments. For the column, a decrease in permeability due to mineral precipitation was estimated, but the permeability estimates were dependent on imaging technique and resolution. X-ray CT imaging has the advantage of reconstructing a 3D pore network while 2D SEM imaging can easily analyze sub-grain and intragranular variations in mineralogy. Pore network models informed by analyses of 2D and 3D images at comparable resolutions produced permeability esti- mates with relatively good agreement. Large discrepancies in predicted permeabilities resulted from small variations in image resolution. Images with resolutions 0.4 to 4 lm predicted permeabilities differ- ing by orders of magnitude. While lower-resolution scans can analyze larger specimens, small pore throats may be missed due to resolution limitations, which in turn overestimates permeability in a pore-network model in which pore-to-pore conductances are statistically assigned. Conversely, high-res- olution scans are capable of capturing small pore throats, but if they are not actually flow-conducting predicted permeabilities will be below expected values. In addition, permeability is underestimated due to misinterpreting surface-roughness features as small pore throats. Comparison of permeability pre- dictions with expected and measured permeability values showed that the largest discrepancies resulted from the highest resolution images and the best predictions of

EFSA Panel on Dietetic Products, Nutrition and Allergies (NDA); Scientific Opinion on the substantiation of a health claim related to flaxseed oil and vitamin E and maintenance of the skin permeability barrier function pursuant to Article 13(5) of Regulation (EC) No 1924/2006

DEFF Research Database (Denmark)

Tetens, Inge

related to a combination of flaxseed oil and vitamin E and maintenance of the skin permeability barrier function. The food constituent that is the subject of the health claim is a combination of flaxseed oil and vitamin E. The Panel considers that the combination of flaxseed oil and vitamin E...... be drawn from these studies for the scientific substantiation of the claim. The Panel concludes that a cause and effect relationship has not been established between the consumption of a combination of flaxseed oil and vitamin E and maintenance of the skin permeability barrier function...... is sufficiently characterised. The claimed effect is “contributes to maintain skin permeability barrier function”. The target population proposed by the applicant is healthy adults with dry and sensitive skin. Maintenance of the permeability barrier function of the skin is a beneficial physiological effect...

Evaluation of the effect of macerals on coal permeability in Tazareh and Parvadeh mines

Directory of Open Access Journals (Sweden)

Farhang Sereshki

2016-08-01

Full Text Available In recent decades, the subject of gas emission in underground coal mines in many countries is an important subject. Many factors affect in gas emissions in coal seams. Geological and physical structures of coal are affecting on gas emissions'. Also, composition and mineralization of coal, affect in coal permeability for different gases. In this study, the relationship between maceral composition and coal permeability in Tazareh and Parvadeh mines has been studied. Accordingly, a laboratory studies to investigate the relationship between coal composition and coal permeability was done. In coal samples, with MFORR equipment the permeability test was done. With microscopic analysis, the maceral contents of coal such as Inertinite and Vitrinite have been measured. Accordingly, many coal samples of Parvadeh and Tazareh coal mines have the pyrite as the dominant mineral matter. Parvadeh coal samples has the average percentage of Vitrinite equal 81.34% and 10.52% Inertinite. Also, in the Tazareh coal samples in Eastern Alborz coal mines, the average percentage of Vitrinite is 69.31% and inertinite is 22.47%. The average percentage of Pyrite content in Parvadeh coal samples in Tabas coal mines is 2.38% and in the Tazareh coal samples in Eastern Alborz coal mines is 2.62%.  The permeability test results have been shown, which, with increase of Inertinite contents, the permeability of coal is increasing. Also, test results have been shown, there was a reduction in the coal permeability with increasing of mineral contents and carbonate contents of the coal. So, the coal permeability in Tabas coal samples is more than Eastern Alborz coal samples.

Effects of Atelocollagen Formulation Containing Oligonucleotide on Endothelial Permeability

Directory of Open Access Journals (Sweden)

Koji Hanai

2012-01-01

Full Text Available Atelocollagen is a major animal protein that is used as a highly biocompatible biomaterial. To date, atelocollagen has been used as an effective drug delivery technology to sustain the release of antitumor proteins and to enhance the antitumor activity of oligonucleotides in in vivo models. However, the biological effects of this technology are not fully understood. In the present study, we investigated the effects of atelocollagen on endothelial paracellular barrier function. An atelocollagen formulation containing oligonucleotides specifically increased the permeability of two types of endothelial cells, and the change was dependent on the molecular size, structure of the oligonucleotides used and the concentrations of the oligonucleotide and atelocollagen in the formulation. An immunohistochemical examination revealed that the formulation had effects on the cellular skeleton and intercellular structure although it did not affect the expression of adherens junction or tight junction proteins. These changes were induced through p38 MAP kinase signaling. It is important to elucidate the biological functions of atelocollagen in order to be able to exploit its drug delivery properties.

The role of python eggshell permeability dynamics in a respiration-hydration trade-off.

Science.gov (United States)

Stahlschmidt, Zachary R; Heulin, Benoit; DeNardo, Dale F

2010-01-01

Parental care is taxonomically widespread because it improves developmental conditions and thus fitness of offspring. Although relatively simplistic compared with parental behaviors of other taxa, python egg-brooding behavior exemplifies parental care because it mediates a trade-off between embryonic respiration and hydration. However, because egg brooding increases gas-exchange resistance between embryonic and nest environments and because female pythons do not adjust their brooding behavior in response to the increasing metabolic requirements of developing offspring, python egg brooding imposes hypoxic costs on embryos during the late stages of incubation. We conducted a series of experiments to determine whether eggshells coadapted with brooding behavior to minimize the negative effects of developmental hypoxia. We tested the hypotheses that python eggshells (1) increase permeability over time to accommodate increasing embryonic respiration and (2) exhibit permeability plasticity in response to chronic hypoxia. Over incubation, we serially measured the atomic and structural components of Children's python (Antaresia childreni) eggshells as well as in vivo and in vitro gas exchange across eggshells. In support of our first hypothesis, A. childreni eggshells exhibited a reduced fibrous layer, became more permeable, and facilitated greater gas exchange as incubation progressed. Our second hypothesis was not supported, as incubation O(2) concentration did not affect the shells' permeabilities to O(2) and H(2)O vapor. Our results suggest that python eggshell permeability changes during incubation but that the alterations over time are fixed and independent of environmental conditions. These findings are of broad evolutionary interest because they demonstrate that, even in relatively simple parental-care models, successful parent-offspring relationships depend on adjustments made by both the parent (i.e., egg-brooding behavioral shifts) and the offspring (i

Permeability of WIPP Salt During Damage Evolution and Healing

International Nuclear Information System (INIS)

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

1999-01-01

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

Compression characteristics and permeability of saturated Gaomiaozi ca-bentonite

International Nuclear Information System (INIS)

Sun Wenjing; Sun De'an; Fang Lei

2012-01-01

The compression characteristics and permeability of compacted Gaomiaozi Ca-bentonite saturated by the water uptake tests are studied by conducting a series of one-dimension compression tests. The permeability coefficient can be calculated by the Terzaghi's one-dimensional consolidation theory after the consolidation coefficient is obtained by the square root of time method. It is found that the compression curves of compacted specimens saturated by the water uptake tests tend to be consistent in the relatively high stress range. The compression indexes show a linear decrease with increasing dry density and the swelling index is a constant. The permeability coefficient decreases with increasing compression stress, and they show the linear relationship in double logarithmic coordinates. Meanwhile, the permeability coefficient shows a linear decrease with decreasing void ratio, which has no relationship with initial states, stress states and stress paths. The permeability coefficient k of GMZ Ca-bentonite at dry density Pd of 1.75 g/cm 3 can be calculated as 2.0 × 10 -11 cm/s by the linear relationship between Pd and log k. It is closed to the permeability coefficient of GMZ Ca-bentonite with the same dry density published in literature, which testifies that the method calculating the permeability coefficient is feasible from the consolidation coefficient obtained by the consolidation test. (authors)

Numerical Simulation of Hydraulic Fracturing in Low-/High-Permeability, Quasi-Brittle and Heterogeneous Rocks

Science.gov (United States)

Pakzad, R.; Wang, S. Y.; Sloan, S. W.

2018-04-01

In this study, an elastic-brittle-damage constitutive model was incorporated into the coupled fluid/solid analysis of ABAQUS to iteratively calculate the equilibrium effective stress of Biot's theory of consolidation. The Young's modulus, strength and permeability parameter of the material were randomly assigned to the representative volume elements of finite element models following the Weibull distribution function. The hydraulic conductivity of elements was associated with their hydrostatic effective stress and damage level. The steady-state permeability test results for sandstone specimens under different triaxial loading conditions were reproduced by employing the same set of material parameters in coupled transient flow/stress analyses of plane-strain models, thereby indicating the reliability of the numerical model. The influence of heterogeneity on the failure response and the absolute permeability was investigated, and the post-peak permeability was found to decrease with the heterogeneity level in the coupled analysis with transient flow. The proposed model was applied to the plane-strain simulation of the fluid pressurization of a cavity within a large-scale block under different conditions. Regardless of the heterogeneity level, the hydraulically driven fractures propagated perpendicular to the minimum principal far-field stress direction for high-permeability models under anisotropic far-field stress conditions. Scattered damage elements appeared in the models with higher degrees of heterogeneity. The partially saturated areas around propagating fractures were simulated by relating the saturation degree to the negative pore pressure in low-permeability blocks under high pressure. By replicating previously reported trends in the fracture initiation and breakdown pressure for different pressurization rates and hydraulic conductivities, the results showed that the proposed model for hydraulic fracture problems is reliable for a wide range of

Effect of acute, slightly increased intra-abdominal pressure on intestinal permeability and oxidative stress in a rat model.

Directory of Open Access Journals (Sweden)

Yuxin Leng

Full Text Available INTRODUCTION: Intra-abdominal hypertension (IAH is known as a common, serious complication in critically ill patients. Bacterial translocation and permeability changes are considered the pathophysiological bases for IAH-induced enterogenic endotoxemia and subsequent multiorgan failure. Nevertheless, the effects of slightly elevated intra-abdominal pressures (IAPs on the intestinal mucosa and the associated mechanisms remain unclear. METHODS: To investigate the acute effects of different nitrogen pneumoperitoneum grades on colonic mucosa, male Sprague-Dawley rats were assigned to six groups with different IAPs (0 [control], 4, 8, 12, 16, and 20 mmHg, n = 6/group. During 90 min of exposure, we dynamically monitored the heart rate and noninvasive hemodynamic parameters. After gradual decompression, arterial blood gas analyses were conducted. Thereafter, structural injuries to the colonic mucosa were identified using light microscopy. Colon permeability was determined using the expression of tight junction proteins, combined with fluorescein isothiocyanate dextran (FD-4 absorption. The pro-oxidant-antioxidant balance was determined based on the levels of malondialdehyde (MDA and antioxidant enzymes. RESULTS: IAH significantly affected the histological scores of the colonic mucosa, tight junction protein expression, mucosal permeability, and pro-oxidant-antioxidant balance. Interestingly, elevations of IAP that were lower than the threshold for IAH also showed a similar, undesirable effect. In the 8 mmHg group, mild hyponatremia, hypocalcemia, and hypoxemia occurred, accompanied by reduced blood and abdominal perfusion pressures. Mild microscopic inflammatory infiltration and increased MDA levels were also detected. Moreover, an 8-mm Hg IAP markedly inhibited the expression of tight junction proteins, although no significant differences in FD-4 permeability were observed between the 0- and 8-mmHg groups. CONCLUSIONS: Acute exposure to slightly

Analysis of Fault Permeability Using Mapping and Flow Modeling, Hickory Sandstone Aquifer, Central Texas

Energy Technology Data Exchange (ETDEWEB)

Nieto Camargo, Jorge E., E-mail: jorge.nietocamargo@aramco.com; Jensen, Jerry L., E-mail: jjensen@ucalgary.ca [University of Calgary, Department of Chemical and Petroleum Engineering (Canada)

2012-09-15

Reservoir compartments, typical targets for infill well locations, are commonly created by faults that may reduce permeability. A narrow fault may consist of a complex assemblage of deformation elements that result in spatially variable and anisotropic permeabilities. We report on the permeability structure of a km-scale fault sampled through drilling a faulted siliciclastic aquifer in central Texas. Probe and whole-core permeabilities, serial CAT scans, and textural and structural data from the selected core samples are used to understand permeability structure of fault zones and develop predictive models of fault zone permeability. Using numerical flow simulation, it is possible to predict permeability anisotropy associated with faults and evaluate the effect of individual deformation elements in the overall permeability tensor. We found relationships between the permeability of the host rock and those of the highly deformed (HD) fault-elements according to the fault throw. The lateral continuity and predictable permeability of the HD fault elements enhance capability for estimating the effects of subseismic faulting on fluid flow in low-shale reservoirs.

Development and characterization of a new oral dapsone nanoemulsion system: permeability and in silico bioavailability studies.

Science.gov (United States)

Monteiro, Lidiane M; Lione, Viviane F; do Carmo, Flavia A; do Amaral, Lilian H; da Silva, Julianna H; Nasciutti, Luiz E; Rodrigues, Carlos R; Castro, Helena C; de Sousa, Valeria P; Cabral, Lucio M

2012-01-01

Dapsone is described as being active against Mycobacterium leprae, hence its role in the treatment of leprosy and related pathologies. Despite its therapeutic potential, the low solubility of dapsone in water results in low bioavailability and high microbial resistance. Nanoemulsions are pharmaceutical delivery systems derived from micellar solutions with a good capacity for improving absorption. The aim of this work was to develop and compare the permeability of a series of dapsone nanoemulsions in Caco-2 cell culture against that of effective permeability in the human body simulated using Gastroplus™ software. The release profiles of the dapsone nanoemulsions using different combinations of surfactants and cosolvent showed a higher dissolution rate in simulated gastric and enteric fluid than did the dispersed dapsone powder. The drug release kinetics were consistent with a Higuchi model. This comparison of dapsone permeability in Caco-2 cells with effective permeability in the human body simulated by Gastroplus showed a good correlation and indicates potential improvement in the biodisponibility of dapsone using this new system.

Effects of Bioadvection by Arenicola marina on Microphytobenthos in Permeable Sediments.

Directory of Open Access Journals (Sweden)

Arjun Chennu

Full Text Available We used hyperspectral imaging to study short-term effects of bioturbation by lugworms (Arenicola marina on the surficial biomass of microphytobenthos (MPB in permeable marine sediments. Within days to weeks after the addition of a lugworm to a homogenized and recomposed sediment, the average surficial MPB biomass and its spatial heterogeneity were, respectively, 150-250% and 280% higher than in sediments without lugworms. The surficial sediment area impacted by a single medium-sized lugworm (~4 g wet weight over this time-scale was at least 340 cm2. While sediment reworking was the primary cause of the increased spatial heterogeneity, experiments with lugworm-mimics together with modeling showed that bioadvective porewater transport from depth to the sediment surface, as induced by the lugworm ventilating its burrow, was the main cause of the increased surficial MPB biomass. Although direct measurements of nutrient fluxes are lacking, our present data show that enhanced advective supply of nutrients from deeper sediment layers induced by faunal ventilation is an important mechanism that fuels high primary productivity at the surface of permeable sediments even though these systems are generally characterized by low standing stocks of nutrients and organic material.

Effects of Bioadvection by Arenicola marina on Microphytobenthos in Permeable Sediments.

Science.gov (United States)

Chennu, Arjun; Volkenborn, Nils; de Beer, Dirk; Wethey, David S; Woodin, Sarah A; Polerecky, Lubos

2015-01-01

We used hyperspectral imaging to study short-term effects of bioturbation by lugworms (Arenicola marina) on the surficial biomass of microphytobenthos (MPB) in permeable marine sediments. Within days to weeks after the addition of a lugworm to a homogenized and recomposed sediment, the average surficial MPB biomass and its spatial heterogeneity were, respectively, 150-250% and 280% higher than in sediments without lugworms. The surficial sediment area impacted by a single medium-sized lugworm (~4 g wet weight) over this time-scale was at least 340 cm2. While sediment reworking was the primary cause of the increased spatial heterogeneity, experiments with lugworm-mimics together with modeling showed that bioadvective porewater transport from depth to the sediment surface, as induced by the lugworm ventilating its burrow, was the main cause of the increased surficial MPB biomass. Although direct measurements of nutrient fluxes are lacking, our present data show that enhanced advective supply of nutrients from deeper sediment layers induced by faunal ventilation is an important mechanism that fuels high primary productivity at the surface of permeable sediments even though these systems are generally characterized by low standing stocks of nutrients and organic material.

Permeability Estimation of Rock Reservoir Based on PCA and Elman Neural Networks

Science.gov (United States)

Shi, Ying; Jian, Shaoyong

2018-03-01

an intelligent method which based on fuzzy neural networks with PCA algorithm, is proposed to estimate the permeability of rock reservoir. First, the dimensionality reduction process is utilized for these parameters by principal component analysis method. Further, the mapping relationship between rock slice characteristic parameters and permeability had been found through fuzzy neural networks. The estimation validity and reliability for this method were tested with practical data from Yan’an region in Ordos Basin. The result showed that the average relative errors of permeability estimation for this method is 6.25%, and this method had the better convergence speed and more accuracy than other. Therefore, by using the cheap rock slice related information, the permeability of rock reservoir can be estimated efficiently and accurately, and it is of high reliability, practicability and application prospect.

METHODOLOGY FOR CALCULATION OF HORIZONTAL WATER PERMEABILITY COEFFICIENT IN SOIL CAPILLARY BORDER

Directory of Open Access Journals (Sweden)

E. I. Michnevich

2011-01-01

Full Text Available The paper shows that for overall estimation of soil water permeability it is necessary to know a horizontal water permeability value of a soil capillary border in addition to coefficients of filtration and permeability. Relations allowing to determine soil permeability in the area of incomplete saturation, are given in the paper. For a fully developed capillary border some calculation formulae have been obtained in the form of algebraic polynomial versus soil grading (grain composition. These formulae allow to make more accurate calculations while designing and operating  reclamation works.

Permeability and compression characteristics of municipal solid waste samples

Science.gov (United States)

Durmusoglu, Ertan; Sanchez, Itza M.; Corapcioglu, M. Yavuz

2006-08-01

Four series of laboratory tests were conducted to evaluate the permeability and compression characteristics of municipal solid waste (MSW) samples. While the two series of tests were conducted using a conventional small-scale consolidometer, the two others were conducted in a large-scale consolidometer specially constructed for this study. In each consolidometer, the MSW samples were tested at two different moisture contents, i.e., original moisture content and field capacity. A scale effect between the two consolidometers with different sizes was investigated. The tests were carried out on samples reconsolidated to pressures of 123, 246, and 369 kPa. Time settlement data gathered from each load increment were employed to plot strain versus log-time graphs. The data acquired from the compression tests were used to back calculate primary and secondary compression indices. The consolidometers were later adapted for permeability experiments. The values of indices and the coefficient of compressibility for the MSW samples tested were within a relatively narrow range despite the size of the consolidometer and the different moisture contents of the specimens tested. The values of the coefficient of permeability were within a band of two orders of magnitude (10-6-10-4 m/s). The data presented in this paper agreed very well with the data reported by previous researchers. It was concluded that the scale effect in the compression behavior was significant. However, there was usually no linear relationship between the results obtained in the tests.

Permeability, storage and hydraulic diffusivity controlled by earthquakes

Science.gov (United States)

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

2016-12-01

Earthquakes can increase permeability in fractured rocks. In the farfield, such permeability increases are attributed to seismic waves and can last for months after the initial earthquake. Laboratory studies suggest that unclogging of fractures by the transient flow driven by seismic waves is a viable mechanism. These dynamic permeability increases may contribute to permeability enhancement in the seismic clouds accompanying hydraulic fracking. Permeability enhancement by seismic waves could potentially be engineered and the experiments suggest the process will be most effective at a preferred frequency. We have recently observed similar processes inside active fault zones after major earthquakes. A borehole observatory in the fault that generated the M9.0 2011 Tohoku earthquake reveals a sequence of temperature pulses during the secondary aftershock sequence of an M7.3 aftershock. The pulses are attributed to fluid advection by a flow through a zone of transiently increased permeability. Directly after the M7.3 earthquake, the newly damaged fault zone is highly susceptible to further permeability enhancement, but ultimately heals within a month and becomes no longer as sensitive. The observation suggests that the newly damaged fault zone is more prone to fluid pulsing than would be expected based on the long-term permeability structure. Even longer term healing is seen inside the fault zone of the 2008 M7.9 Wenchuan earthquake. The competition between damage and healing (or clogging and unclogging) results in dynamically controlled permeability, storage and hydraulic diffusivity. Recent measurements of in situ fault zone architecture at the 1-10 meter scale suggest that active fault zones often have hydraulic diffusivities near 10-2 m2/s. This uniformity is true even within the damage zone of the San Andreas fault where permeability and storage increases balance each other to achieve this value of diffusivity over a 400 m wide region. We speculate that fault zones

Fluid flow simulation and permeability computation in deformed porous carbonate grainstones

Science.gov (United States)

Zambrano, Miller; Tondi, Emanuele; Mancini, Lucia; Lanzafame, Gabriele; Trias, F. Xavier; Arzilli, Fabio; Materazzi, Marco; Torrieri, Stefano

2018-05-01

In deformed porous carbonates, the architecture of the pore network may be modified by deformation or diagenetic processes altering the permeability with respect to the pristine rock. The effects of the pore texture and morphology on permeability in porous rocks have been widely investigated due to the importance during the evaluation of geofluid reservoirs. In this study, these effects are assessed by combining synchrotron X-ray computed microtomography (SR micro-CT) and computational fluid dynamics. The studied samples pertain to deformed porous carbonate grainstones highly affected by deformation bands (DBs) exposed in Northwestern Sicily and Abruzzo regions, Italy. The high-resolution SR micro-CT images of the samples, acquired at the SYRMEP beamline of the Elettra - Sincrotrone Trieste laboratory (Italy), were used for simulating a pressure-driven flow by using the lattice-Boltzmann method (LBM). For the experiments, a multiple relaxation time (MRT) model with the D3Q19 scheme was used to avoid viscosity-dependent results of permeability. The permeability was calculated using Darcy's law once steady conditions were reached. After the simulations, the pore-network properties (effective porosity, specific surface area, and geometrical tortuosity) were calculated using 3D images of the velocity fields. These images were segmented considering a velocity threshold value higher than zero. The study showed that DBs may generate significant heterogeneity and anisotropy of the permeability of the evaluated rock samples. Cataclasis and cementation process taking place within the DBs reduce the effective porosity and therefore the permeability. Contrary to this, pressure dissolution and faulting may generate connected channels which contribute to the permeability only parallel to the DB.

Intestinal Permeability of β-Lapachone and Its Cyclodextrin Complexes and Physical Mixtures.

Science.gov (United States)

Mangas-Sanjuan, Victor; Gutiérrez-Nieto, Jorge; Echezarreta-López, Magdalena; González-Álvarez, Isabel; González-Álvarez, Marta; Casabó, Vicente-Germán; Bermejo, Marival; Landin, Mariana

2016-12-01

β-Lapachone (βLAP) is a promising, poorly soluble, antitumoral drug. βLAP combination with cyclodextrins (CDs) improves its solubility and dissolution but there is not enough information about the impact of cyclodextrins on βLAP intestinal permeability. The objectives of this work were to characterize βLAP intestinal permeability and to elucidate cyclodextrins effect on the dissolution properties and on the intestinal permeability. The final goal was to evaluate CDs influence on the oral absorption of βLAP. Binary systems (physical mixtures and inclusion complexes) including βLAP and CDs (β-cyclodextrin: βCD, random-methyl-β-cyclodextrin: RMβCD and sulfobutylether-β-cyclodextrin: SBEβCD) have been prepared and analysed by differential scanning calorimetry. βLAP (and its combinations with CDs) absorption rate coefficients and effective permeability values have been determined in vitro in MDCK or MDCK-Mdr1 monolayers and in situ in rat by a closed loop perfusion technique. DSC results confirmed the formation of the inclusion complexes. βLAP-CDs inclusion complexes improve drug solubility and dissolution rate in comparison with physical mixtures. βLAP presented a high permeability value which can provide complete oral absorption. Its oral absorption is limited by its low solubility and dissolution rate. Cyclodextrin (both as physical mixtures and inclusion complexes) showed a positive effect on the intestinal permeability of βLAP. Complexation with CDs does not reduce βLAP intestinal permeability in spite of the potential negative effect of the reduction in free fraction of the drug. The use of RMβCD or SBEβCD inclusion complexes could benefit βLAP oral absorption by enhancing its solubility, dissolution rate and permeability.

Investigation clogging dynamic of permeable pavement systems using embedded sensors

Science.gov (United States)

Permeable pavement is a stormwater control measure commonly selected in both new and retrofit applications. However, there is limited information about the clogging mechanism of these systems that effects the infiltration. A permeable pavement site located at the Seitz Elementary...

Water sorption and water permeability properties of edible film made from potato peel waste

Directory of Open Access Journals (Sweden)

Siti Hajar OTHMAN

Full Text Available Abstract The water sorption and permeability properties of edible film produced from potato peel waste was investigated under different levels of relative humidity (23, 33, 43, 57, 75% RH and temperatures (5, 30, 50 °C. The water sorption behaviour and isotherms of the film were investigated by fitting water sorption data to the Peleg model and the Guggenheim, Anderson de Boer model (GAB model. The amount of moisture content, time required for the moisture content of the film to reach equilibrium, water sorption rate, and water sorption capacity increased when the relative humidity increased. The effect of temperature on moisture content, water sorption rate, water sorption capacity, and monolayer moisture content is complex and related to the water activity as well as the moisture content. Based on R2 and RMSE values, the Peleg and GAB models were respectively determined as excellent models to predict the water sorption properties of the films, thus supporting the reliability of water sorption behaviour prediction. The water vapour transmission rate and water vapour permeability increased with an increase in relative humidity and temperature. The sorption and permeability properties of the film are worth investigation since the final application of the film as food packaging is ultimately dependent on these behaviours.

Preliminary study of the irradiation-induced modification of skin permeability

International Nuclear Information System (INIS)

Coelho, R.; Istin, M.

1978-01-01

Irradiation of the skin of an animal leads immediately to a strong increase in vascular permeability. If a dye is at once injected intraveinously it diffuses very rapidly in the irradiated zone, this becomes highly coloured and the colour intensity measurement gives a clue to the severity of the lesions produced. This phenomenon has been used in the past as a pharmacological test to study vascular permeability and is employed in this work to observe the effect of diosmine-titrated flavonoids on vascular permeability in inflammatory diseases. The capillary permeability increase due to local γ irradiation of rabbit skin has been accurately determined by measurement of the colouration observed after injection of Geigy Blue. Diosmine, injected intraperitoneally, protects the vascular system against increased permeability due to ionising radiations [fr

Permeability and Dispersion Coefficients in Rocks with Fracture Network - 12140

Energy Technology Data Exchange (ETDEWEB)

Lee, C.K.; Htway, M.Z. [Handong Global University, 3 Namsong-ri, Heunghae-eub, Buk-gu, Pohang, Kyungbuk, 791-708 (Korea, Republic of); Yim, S.P. [Korea Atomic Energy Research Institute, P.O.Box 150, Yusong, Daejon, 305-600 (Korea, Republic of)

2012-07-01

Fluid flow and solute transport are considered for a rock medium with a fracture network with regard to the effective permeability and the dispersion coefficients. To investigate the effects of individual fractures a three-fracture system is chosen in which two are parallel and the third one connects the two at different angles. Specifically the micro-cell boundary-value problems(defined through multiple scale analysis) are solved numerically by using finite elements to calculate the permeability and dispersion coefficients. It is shown that the permeability depends significantly on the pattern of the fracture distribution and the dispersion coefficient is influenced by both the externally imposed pressure gradient (which also reflects the flow field) and the direction of the gradient of solute concentration on the macro-scale. From the calculations of the permeability and dispersion coefficients for solute in a rock medium with a fracture network the following conclusions are drawn. 1. The permeability of fractured medium depends on the primary orientation of the fracture network and is influenced by the connecting fractures in the medium. 2. The cross permeability, e.g., permeability in the direction normal to the direction of the external pressure gradient is rather insensitive to the orientation of the fracture network. 3. Calculation of permeability is most efficiently achieved with optimal discretization across individual fractures and is rather insensitive to the discretization along the fracture.. 4. The longitudinal dispersion coefficient Dxx of a fractured medium depends on both the macro-scale concentration gradient and the direction of the flow (pressure gradient). Hence both features must be considered when investigating solute transport in a fractured medium. (authors)

Effects of discontinuous magnetic permeability on magnetodynamic problems

KAUST Repository

Guermond, J.-L.

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. © 2011 Elsevier Inc.

The Effect of Ovariectomy and Estrogen on Penetrating Brain Arterioles and Blood-Brain Barrier Permeability

NARCIS (Netherlands)

Cipolla, Marilyn J.; Godfrey, Julie A.; Wiegman, Marchien J.

2009-01-01

Objective: We investigated the effect of estrogen replacement on the structure and function of penetrating brain arterioles (PA) and blood-brain barrier (BBB) permeability. Materials and Methods: Female ovariectomized Sprague-Dawley rats were replaced with estradiol (E-2) and estriol (E-3) (OVX + E;

Front gardens to car parks: changes in garden permeability and effects on flood regulation.

Science.gov (United States)

Warhurst, Jennifer R; Parks, Katherine E; McCulloch, Lindsay; Hudson, Malcolm D

2014-07-01

This study addresses the consequences of widespread conversion of permeable front gardens to hard standing car parking surfaces, and the potential consequences in high-risk urban flooding hotspots, in the city of Southampton. The last two decades has seen a trend for domestic front gardens in urban areas to be converted for parking, driven by the lack of space and increased car ownership. Despite media and political attention, the effects of this change are unknown, but increased and more intense rainfall, potentially linked to climate change, could generate negative consequences as runoff from impermeable surfaces increases. Information is limited on garden permeability change, despite the consequences for ecosystem services, especially flood regulation. We focused on eight flooding hotspots identified by the local council as part of a wider urban flooding policy response. Aerial photographs from 1991, 2004 and 2011 were used to estimate changes in surface cover and to analyse permeability change within a digital surface model in a GIS environment. The 1, 30 and 100 year required attenuation storage volumes were estimated, which are the temporary storage required to reduce the peak flow rate given surface permeability. Within our study areas, impermeable cover in domestic front gardens increased by 22.47% over the 20-year study period (1991-2011) and required attenuation storage volumes increased by 26.23% on average. These increases suggest that a consequence of the conversion of gardens to parking areas will be a potential increase in flooding frequency and severity - a situation which is likely to occur in urban locations worldwide. Copyright © 2014 Elsevier B.V. All rights reserved.

The effect of air permeability characteristics of protective garments on the induced physiological strain under exercise-heat stress.

Science.gov (United States)

Epstein, Yoram; Heled, Yuval; Ketko, Itay; Muginshtein, Jeni; Yanovich, Ran; Druyan, Amit; Moran, Daniel S

2013-08-01

The high values of thermal resistance (Rct) and/or vapor resistance (Ret) of chemical protective clothing (CPC) induce a considerable thermal stress. The present study compared the physiological strain induced by CPCs and evaluates the relative importance of the fabrics' Rct, Ret, and air permeability in determining heat strain. Twelve young (20-30 years) healthy, heat-acclimated male subjects were exposed fully encapsulated for 3h daily to an exercise-heat stress (35°C and 30% relative humidity, walking on a motor-driven treadmill at a pace of 5 km h(1) and a 4% inclination, in a work-rest cycle of 45 min work and 15 min rest). Two bipack CPCs (PC1 and PC2) were tested and the results were compared with those attained by two control suits-a standard cotton military BDU (CO1) and an impermeable material suit (CO2). The physiological burden imposed by the two bilayer garments was within the boundaries set by the control conditions. Overall, PC2 induced a lower strain, which was closer to CO1, whereas PC1 was closer to CO2. Air permeability of the PC2 cloth was almost three times higher than that of PC1, enabling a better heat dissipation and consequently a lower physiological strain. Furthermore, air permeability characteristic of the fabrics, which is associated with its construction and weave, significantly correlated with the physiological strain, whereas the correlation with Rct, Ret, and weight was poor. The results emphasize the importance of air permeability in reducing the physiological strain induced by CPCs.

Calculation of Permeability inside the Basket including one Fuel Assembly

Energy Technology Data Exchange (ETDEWEB)

Yu, Seung Hwan; Bang, Kyung Sik; Lee, Ju an; Choi, Woo Seok [KAERI, Daejeon (Korea, Republic of)

2016-05-15

In general, the porous media model and the effective thermal conductivity were used to simply the fuel assembly. The methods of calculating permeability were compared considering the flow inside a basket which includes a nuclear fuel. Detailed fuel assembly was a computational modeling and the flow characteristics were investigated. The flow inside the basket which included a fuel assembly is analyzed by CFD. As the height of the fuel assembly increases, the pressure drop linearly increased. The inertia resistance could be neglected. Three methods to calculate the permeability were compared. The permeability by the friction factor is 50% less than the permeability by wall shear stress and pressure drop.

Quantifying the Effects of Spatial Uncertainty in Fracture Permeability on CO2 Leakage through Columbia River Basalt Flow Interiors

Science.gov (United States)

Gierzynski, A.; Pollyea, R.

2016-12-01

Recent studies suggest that continental flood basalts may be suitable for geologic carbon sequestration, due to fluid-rock reactions that mineralize injected CO2 on relatively short time-scales. Flood basalts also possess a morphological structure conducive to injection, with alternating high-permeability (flow margin) and low-permeability (flow interior) layers. However, little information exists on the behavior of CO2 migration within field-scale fracture networks, particularly within flow interiors and at conditions near the critical point for CO2. In this study, numerical simulation is used to investigate the influence of fracture permeability uncertainty during gravity-driven CO2 migration within a jointed basalt flow interior as CO2 undergoes phase change from supercritical fluid to a subcritical phase. The model domain comprises a 2D fracture network mapped with terrestrial LiDAR scans of Columbia River Basalt acquired near Starbuck, WA. The model domain is 5 m × 5 m with bimodal heterogeneity (fracture and matrix), and initial conditions corresponding to a hydrostatic pressure gradient between 750 and 755 m depth. Under these conditions, the critical point for CO2 occurs 1.5 m above the bottom of the domain. For this model scenario, CO2 enters the base of the fracture network at 0.5 MPa overpressure, and matrix permeability is assumed constant. Fracture permeability follows a lognormal distribution on the basis of fracture aperture values from literature. In order to account for spatial uncertainty, the lognormal fracture permeability distribution is randomly located in the model domain and CO2 migration is simulated within the same fracture network for 50 equally probable realizations. Model results suggest that fracture connectivity, which is independent of permeability distribution, governs the path taken by buoyant CO2 as it rises through the flow interior; however, the permeability distribution strongly governs the CO2 flux magnitude. In particular

Air-injection field tests to determine the effect of a heat cycle on the permeability of welded tuff

International Nuclear Information System (INIS)

Lee, K.H.; Ueng, Tzou-Shin.

1991-01-01

As part of a series of prototype tests conducted in preparation for site characterization of the potential nuclear-waste repository site at Yucca Mountain, Nevada, air-injection tests were conducted in the welded tuffs in G-Tunnel at the Nevada Test Site. The objectives were to characterize the permeability of the highly fractured tuff around a horizontal heater emplacement borehole, and to determine the effect of a heating and cooling cycle on the rock-mass permeability. Air was injected into packed-off intervals along the heater borehole. The bulk permeability of the rock adjacent to the test interval and the aperture of fractures intersecting the interval were computed from the air-flow rate, temperature, and pressure at steady state. The bulk permeability of intervals along with borehole varied from a minimum of 0.08 D to a maximum of over 144 D and the equivalent parallel-plate apertures of fractures intersecting the borehole varied from 70 to 589 μm. Higher permeabilities seemed to correlate spatially with the mapped fractures. The rock was then heated for a period of 6.5 months with an electrical-resistive heater installed in the borehole. After heating, the rock was allowed to cool down to the ambient temperature. The highest borehole wall temperature measured was 242 degree C. Air injection tests were repeated following the heating and cooling cycle, and the results showed significant increases in bulk permeability ranging from 10 to 1830% along the borehole. 8 ref., 6 figs., 3 tabs

Comparison of Mass Transfer Models for Determination of the Intestinal Permeability

Directory of Open Access Journals (Sweden)

P Zakeri-Milani

2008-09-01

Full Text Available Background and the purpose of the study: In determination of the permeability of the intestinal wall by external perfusion techniques, several models have been proposed. In the present study three models were used for experimental results that differ in their convection and diffusion assumptions. Material and Methods: Permeability coefficients for 13 compounds (metoprolol, propranolol, naproxen, ketoprofen, furosemide, hydrochlorothiazide, cimetidine, ranitidine, atenolol, piroxicam, antipyrine, ibuprofen and carbamazepine with known human intestinal permeability values were determined in anaesthetized rats by different mass transfer models and plotted versus the observed human intestinal permeabilities. Results: The calculated dimensionless wall permeability values were in the range of 0.37 - 4.85, 0.38-6.54 and 0.41-16.59 for complete radial mixing, mixing tank and laminar flow models respectively. The results indicated that all of the models work relatively well for our data despite fundamentally different assumptions. The wall permeabilities were in the order laminar flow > mixing tank > complete radial mixing. Conclusion: Although laminar flow model provides the most direct measure of the intrinsic wall permeability, it has limitations for highly permeable drugs such as ibuprofen. The normal physiological hydrodynamics is more complex and more investigation is required to find out the real hydrodynamics.

Foam film permeability: theory and experiment.

Science.gov (United States)

Farajzadeh, R; Krastev, R; Zitha, Pacelli L J

2008-02-28

The mass transfer of gas through foam films is a prototype of various industrial and biological processes. The aim of this paper is to give a perspective and critical overview of studies carried out to date on the mass transfer of gas through foam films. Contemporary experimental data are summarized, and a comprehensive overview of the theoretical models used to explain the observed effects is given. A detailed description of the processes that occur when a gas molecule passes through each layer that forms a foam film is shown. The permeability of the film-building surfactant monolayers plays an important role for the whole permeability process. It can be successfully described by the models used to explain the permeability of surfactant monolayers on aqueous sub-phase. For this reason, the present paper briefly discusses the surfactant-induced resistance to mass transfer of gases through gas-liquid interface. One part of the paper discusses the experimental and theoretical aspects of the foam film permeability in a train of foam films in a matrix or a cylinder. This special case is important to explain the gas transfer in porous media or in foams. Finally, this paper will highlight the gaps and challenges and sketch possible directions for future research.

Porosity, petrophysics and permeability of the Whitby Mudstone (UK)

Science.gov (United States)

Houben, M.; Barnhoorn, A.; Hardebol, N.; Ifada, M.; Boersma, Q.; Douma, L.; Peach, C. J.; Bertotti, G.; Drury, M. R.

2016-12-01

Typically pore diameters in shales range from the µm down to the nm scale and the effective permeability of shale reservoirs is a function of the interconnectivity between the pore space and the natural fracture network present. The length and spacing of mechanical induced and natural fractures is one of the factors controlling gas produtivity from unconventional reservoirs. Permeability of the Whitby Mudstone measured on 1 inch cores was linked to microstructure and combined with natural fracture spacing present in outcrops along the Yorkshire coast (UK) to get insight into possible fluid pathways from reservoir to well. We used a combination of different techniques to characterize the porosity (gas adsorption, Scanning Electron Microscopy), mineralogy (X-Ray Fluorescence, X-Ray Diffraction, Scanning Electron Microscopy) and permeability (pressure step decay) of the Whitby Mudstone. In addition, we mapped the natural fracture network as present in outcrops along the Yorkshire coast (UK) at the 10-2-101m scale. Mineralogically we are dealing with a rock that is high in clay content and has an average organic matter content of about 10%. Results show a low porosity (max. 7%) as well as low permeability for the Whitby Mudstone. The permeability, measured parallel to bedding, depends on the confining pressure and is 86 nanodarcy at 10 MPa effective confining pressure and decreases to 16 nanodarcy at 40 MPa effective confining pressure. At the scale of observation the average distance to nearest natural fracture is in the order of 0.13 meter and 90 percent of all matrix elements are spaced within 0.4 meter to the nearest fracture. By assuming darcy flow, a permeability of 100 nanodarcy and 10% of overpressure we calculated that for the Whitby mudstone most of the gas resides in the matrix for less than 60 days until it reaches the fracture network.

Permeability model of sintered porous media: analysis and experiments

Science.gov (United States)

Flórez Mera, Juan Pablo; Chiamulera, Maria E.; Mantelli, Marcia B. H.

2017-11-01

In this paper, the permeability of porous media fabricated from copper powder sintering process was modeled and measured, aiming the use of the porosity as input parameter for the prediction of the permeability of sintering porous media. An expression relating the powder particle mean diameter with the permeability was obtained, based on an elementary porous media cell, which is physically represented by a duct formed by the arrangement of spherical particles forming a simple or orthorhombic packing. A circular duct with variable section was used to model the fluid flow within the porous media, where the concept of the hydraulic diameter was applied. Thus, the porous is modeled as a converging-diverging duct. The electrical circuit analogy was employed to determine two hydraulic resistances of the cell: based on the Navier-Stokes equation and on the Darcýs law. The hydraulic resistances are compared between themselves and an expression to determine the permeability as function of average particle diameter is obtained. The atomized copper powder was sifted to reduce the size dispersion of the particles. The porosities and permeabilities of sintered media fabricated from powders with particle mean diameters ranging from 20 to 200 microns were measured, by means of the image analysis method and using an experimental apparatus. The permeability data of a porous media, made of copper powder and saturated with distilled water, was used to compare with the permeability model. Permeability literature models, which considers that powder particles have the same diameter and include porosity data as input parameter, were compared with the present model and experimental data. This comparison showed to be quite good.

The Effects of Creatine Monohydrate on Permeability of Coronary Artery Endothelium and Level of Blood Lipoprotein in Diabetic Rats.

Science.gov (United States)

Rahmani, Asghar; Asadollahi, Khairollah; Soleimannejad, Kourosh; Khalighi, Zahra; Mohsenzadeh, Yosouf; Hemati, Ruhollah; Moradkhani, Atefeh; Abangah, Ghobad

2016-09-01

Creatine monohydrate has beneficial effects on serum glucose. This study aimed to investigate the effects of creatine on serum biochemical markers and permeability of coronary arteries among diabetic rats. 32 Wistar rats, which weighed 150-200 grams were randomly divided into 4 groups including: group I, control; group II, creatine monohydrate; group III, diabetic rats; and group IV, diabetic rats + creatine. Creatine monohydrate was applied by 400 mg/kg/daily for 5 months. Animals' weights and blood samples were taken before and after the study. Endothelial permeability rate was measured by Evans Blue method. Data were analysed by SPSS 16. At the end of fifth month, rats' weights in diabetic group under treatment with creatine, compared to those without, increased significantly (pcreatine (pcreatine compared to untreated groups, closed to the intact group (pcreatine monohydrate caused an improvement of serum biochemical markers associated with diabetes and reduced the permeability rate of coronary arteries among diabetic rats. © 2016 by the Association of Clinical Scientists, Inc.

Problems of increasing of thermostability of highly permeable Ni-Zn ferrites and relative materials for telecommunications

Energy Technology Data Exchange (ETDEWEB)

Gonchar, A. E-mail: letyuk@mail.ru; Andreev, V.; Letyuk, L.; Shishkanov, A.; Maiorov, V

2003-01-01

The work considers ways of increasing of thermostability of ferrites of the basic systems NiO-ZnO-Fe{sub 2}O{sub 3} and MgO-ZnO-Fe{sub 2}O{sub 3} and relative materials for telecommunication. Sufficient results in increasing of the thermostability were achieved by doping Cu ions and controlling rejection of Fe{sub 2}O{sub 3} content from equimolar composition. These results allow to increase the Curie temperature to 130-140 deg. C for Ni-Zn ferrites with initial permeability 2000.

Hydrogen solubility and permeability of Nb-W-Mo alloy membrane

International Nuclear Information System (INIS)

Awakura, Y.; Nambu, T.; Matsumoto, Y.; Yukawa, H.

2011-01-01

Research highlights: → The concept for alloy design of Nb-based hydrogen permeable membrane has been applied to Nb-W-Mo ternary alloy in order to improve further the resistance to hydrogen embrittlement and hydrogen permeability. → The alloying effects of Mo on the hydriding properties of Nb-W alloy have been elucidated. → The addition of Mo and/or W into niobium improves the resistance to hydrogen embrittlement by reducing the dissolved hydrogen concentration in the alloy. → Nb-W-Mo alloy possesses excellent hydrogen permeability together with strong resistance to hydrogen embrittlement. - Abstract: The alloying effects of molybdenum on the hydrogen solubility, the resistance to hydrogen embrittlement and the hydrogen permeability are investigated for Nb-W-Mo system. It is found that the hydrogen solubility decreases by the addition of molybdenum into Nb-W alloy. As a result, the resistance to hydrogen embrittlement improves by reducing the hydrogen concentration in the alloy. It is demonstrated that Nb-5 mol%W-5 mol%Mo alloy possesses excellent hydrogen permeability without showing any hydrogen embrittlement when used under appropriate hydrogen permeation conditions, i.e., temperature and hydrogen pressures.

Steady flow in voids and closed cracks in permeable media

International Nuclear Information System (INIS)

Rae, J.

1985-03-01

This paper considers what happens when a steady flow in a permeable medium meets two concentric spheres which have different permeabilities. This can form a first stage model for water flow near an engineered cavity in rock or a concreted waste package placed in filler material as in a nuclear waste repository. Results are obtained in terms of the simplest spherical harmonics, which lets them be used easily. Included are the well-known result that a highly permeable sphere will see only a few times the flux which would occur if it had the permeability of its surroundings, and the less well-known result, though unsurprising, that a spherical region surrounded by a highly permeable shell will see almost no flow, as it will almost all by-pass. A companion paper will include more geometrical effects by replacing the spheres by ellipsoids. (author)

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

Energy Technology Data Exchange (ETDEWEB)

Han, M., E-mail: mangui@gmail.com [State Key Laboratory of Electronic Thin Films & Integrated Devices, University of Electronic Science and Technology of China, Chengdu (China); Rozanov, K.N.; Zezyulina, P.A. [Institute for Theoretical and Applied Electromagnetics, Russian Academy of Sciences, Moscow (Russian Federation); Wu, Yan-Hui [State Key Laboratory of Electronic Thin Films & Integrated Devices, University of Electronic Science and Technology of China, Chengdu (China)

2015-06-01

Fe–Cu–Nb–Si–B microflakes have been prepared by ball milling. The structural, magnetostatic and microwave permeability of the flakes and flake-filled composites have been studied. Two ferromagnetic phases, nanograins and amorphous matrix, are found in the flakes. The Mössbauer study shows that the nanograins are α-Fe{sub 3}(Si) with D0{sub 3} superlattice structure. High resolution transmission electron microscopy shows that the nanograins are well dispersed in the matrix. The microwave permeability of composites containing the flakes has been measured. The comparison of the intrinsic permeability of the flakes obtained from the permeability measurements and from the anisotropy field distribution reveals a disagreement in the magnetic loss peak location. It is concluded that the low-frequency loss in the composites is not due to the effect of eddy currents. The low-frequency loss may be attributed to other sources, such as domain wall motion or peculiarities of the magnetic structure of the flakes in the composite. - Highlights: • Hyperfine interactions have been studied for the Fe-based nanocomposites. Please see Fig. 3. • The distribution of magnetic anisotropy has been derived from the initial magnetization curve of the composite. Please see Fig. 6. • The magnetic loss peak has been reconstructed from the measured permeability of composites and from the anisotropy field distribution. Please see Fig. 9.

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

International Nuclear Information System (INIS)

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

2015-01-01

Fe–Cu–Nb–Si–B microflakes have been prepared by ball milling. The structural, magnetostatic and microwave permeability of the flakes and flake-filled composites have been studied. Two ferromagnetic phases, nanograins and amorphous matrix, are found in the flakes. The Mössbauer study shows that the nanograins are α-Fe 3 (Si) with D0 3 superlattice structure. High resolution transmission electron microscopy shows that the nanograins are well dispersed in the matrix. The microwave permeability of composites containing the flakes has been measured. The comparison of the intrinsic permeability of the flakes obtained from the permeability measurements and from the anisotropy field distribution reveals a disagreement in the magnetic loss peak location. It is concluded that the low-frequency loss in the composites is not due to the effect of eddy currents. The low-frequency loss may be attributed to other sources, such as domain wall motion or peculiarities of the magnetic structure of the flakes in the composite. - Highlights: • Hyperfine interactions have been studied for the Fe-based nanocomposites. Please see Fig. 3. • The distribution of magnetic anisotropy has been derived from the initial magnetization curve of the composite. Please see Fig. 6. • The magnetic loss peak has been reconstructed from the measured permeability of composites and from the anisotropy field distribution. Please see Fig. 9

The effect of hot water injection on sandstone permeability

DEFF Research Database (Denmark)

Rosenbrand, Esther; Haugwitz, Christian; Jacobsen, Peter Sally Munch

2014-01-01

Seasonal energy storage can be achieved by hot water injection in geothermal sandstone aquifers. We present an analysis of literature data in combination with new short-term flow through permeability experiments in order to address physical and physico-chemical mechanisms that can alter...

Effect on moisture permeability of typewriting on unit dose package surfaces.

Science.gov (United States)

Rackson, J T; Zellhofer, M J; Birmingham, P H

1984-10-01

The effects of typewriting on labels of two unit dose packages with respect to moisture permeability were examined. Using an electric typewriter, a standard label format was imprinted on two different types of class A unit dose packages: (1) a heat-sealed paper-backed foil and cellofilm strip pouch, and (2) a copolyester and polyethylene multiple-cup blister with a heat-sealed paper-backed foil and cellofilm cover. The labels were typed at various typing-element impact settings. The official USP test for water permeation was then performed on typed packages and untyped control packages. The original untyped packages were confirmed to be USP class A quality. The packages for which successively harder impact settings were used showed a corresponding increase in moisture permeability. This resulted in a lowering of USP package ratings from class A to class B and D, some of which would be unsuitable for use in any unit dose system under current FDA repackaging standards. Typing directly onto the label of a unit dose package before it is sealed will most likely damage the package and possibly make it unfit for use. Pharmacists who must type labels for the unit dose packages studied should use the lowest possible typewriter impact setting and test for damage using the USP moisture-permeation test.

[Study on effect of pH on rectum permeability of active ingredients in Reduning suppositories in vitro].

Science.gov (United States)

Yan, Ming; Wei, Ying-chun; Meng, Jin; Xu, Dian-hong; Wu, Yun; Xiao, Wei

2015-04-01

To investigate the effect of different pH on rectum permeability of chlorogenic acid and geniposide. Four kinds of Reduning suppositories of different pH were separated and put into the rectum to study the suppositories in vitro and the content of chlorogenic acid and geniposide samples was determined by HPLC to calculate the permeation in 24 hours. With increase of pH within 2.5-7.4, the steady state flux of chlorogenic acid was increased, but the steady state flux of geniposidesamples was steady. Adjusted the pH can increase the rectum permeability of active ingredients in Reduning auppositories.

Zonulin upregulation is associated with increased gut permeability in subjects with type 1 diabetes and their relatives.

Science.gov (United States)

Sapone, Anna; de Magistris, Laura; Pietzak, Michelle; Clemente, Maria G; Tripathi, Amit; Cucca, Francesco; Lampis, Rosanna; Kryszak, Deborah; Cartenì, Maria; Generoso, Maddalena; Iafusco, Dario; Prisco, Francesco; Laghi, Francesca; Riegler, Gabriele; Carratu, Romano; Counts, Debra; Fasano, Alessio

2006-05-01

Zonulin, a protein that modulates intestinal permeability, is upregulated in several autoimmune diseases and is involved in the pathogenesis of autoimmune diabetes in the BB/Wor animal model of the disease. To verify the association between serum zonulin levels and in vivo intestinal permeability in patients with type 1 diabetes, both parameters were investigated in different stages of the autoimmune process. Forty-two percent (141 of 339) of the patients had abnormal serum zonulin levels, as compared with age-matched control subjects. The increased zonulin levels correlated with increased intestinal permeability in vivo and changes in claudin-1, claudin-2, and myosin IXB genes expression, while no changes were detected in ZO1 and occludin genes expression. When tested in serum samples collected during the pre-type 1 diabetes phase, elevated serum zonulin was detected in 70% of subjects and preceded by 3.5 +/- 0.9 years the onset of the disease in those patients who went on to develop type 1 diabetes. Combined, these results suggest that zonulin upregulation is associated with increased intestinal permeability in a subgroup of type 1 diabetic patients. Zonulin upregulation seems to precede the onset of the disease, providing a possible link between increased intestinal permeability, environmental exposure to non-self antigens, and the development of autoimmunity in genetically susceptible individuals.

Permeability During Magma Expansion and Compaction

Science.gov (United States)

Gonnermann, Helge. M.; Giachetti, Thomas; Fliedner, Céline; Nguyen, Chinh T.; Houghton, Bruce F.; Crozier, Joshua A.; Carey, Rebecca J.

2017-12-01

Plinian lapilli from the 1060 Common Era Glass Mountain rhyolitic eruption of Medicine Lake Volcano, California, were collected and analyzed for vesicularity and permeability. A subset of the samples were deformed at a temperature of 975°, under shear and normal stress, and postdeformation porosities and permeabilities were measured. Almost all undeformed samples fall within a narrow range of vesicularity (0.7-0.9), encompassing permeabilities between approximately 10-15 m2 and 10-10 m2. A percolation threshold of approximately 0.7 is required to fit the data by a power law, whereas a percolation threshold of approximately 0.5 is estimated by fitting connected and total vesicularity using percolation modeling. The Glass Mountain samples completely overlap with a range of explosively erupted silicic samples, and it remains unclear whether the erupting magmas became permeable at porosities of approximately 0.7 or at lower values. Sample deformation resulted in compaction and vesicle connectivity either increased or decreased. At small strains permeability of some samples increased, but at higher strains permeability decreased. Samples remain permeable down to vesicularities of less than 0.2, consistent with a potential hysteresis in permeability-porosity between expansion (vesiculation) and compaction (outgassing). We attribute this to retention of vesicle interconnectivity, albeit at reduced vesicle size, as well as bubble coalescence during shear deformation. We provide an equation that approximates the change in permeability during compaction. Based on a comparison with data from effusively erupted silicic samples, we propose that this equation can be used to model the change in permeability during compaction of effusively erupting magmas.

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

Science.gov (United States)

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

2015-04-01

Tectonized clays are complex materials characterized by several levels of structures that may evolve during load and wetting/drying processes. Some microstructural patterns, as microfissures, have a particular influence on the value of permeability which is one of the main factors controlling pore pressure regime in slopes. In this work, the pore pressure regime measured in a real slope of tectonized clay in Southern Italy is analyzed by a numerical model that considers changes in permeability induced by microfissure closure and opening during the wetting and drying processes resulting from climatic actions. Permeability model accounts for the changes in Pore Size Distribution observed by Microscopy Intrusion Porosimetry. MIP tests are performed on representative samples of ground in initial conditions ("in situ" conditions) and final conditions (deformed sample after applying a wetting path that aims to reproduce the saturation of the soil under heavy rains). The resulting measurements allow for the characterization at microstructural level of the soil, identifying the distribution of dominant families pores in the sample and its evolution under external actions. Moreover, comparison of pore size density functions allows defining a microstructural parameter that depends on void ratio and degree of saturation and controls the variation of permeability. Model has been implemented in a thermo-hydro-mechanical code provided with a special boundary condition for climatic actions. Tool is used to analyze pore pressure measurements obtained in the tectonized clay slope. Results are analyzed at the light of the effect that permeability changes during wetting and drying have on the pore pressure regime.

Sensitivity Analysis of Interfacial Tension on Saturation and Relative Permeability Model Predictions

KAUST Repository

Abdallah, Wael; Zhao, Weishu; Gmira, Ahmed; Negara, Ardiansyah; Buiting, Jan

2011-01-01

Interfacial tension (IFT) measurements of Dodecane/brine systems at different concentrations and Dodecane/deionized water subject to different Dodecane purification cycles were taken over extended durations at room temperature and pressure to investigate the impact of aging. When a fresh droplet was formed, a sharp drop in IFT was observed assumed to be a result of intrinsic impurity adsorption at the interface. The subsequent measurements exhibited a prolonged equilibration period consistent with diffusion from the bulk phase to the interface. Our results indicate that minute amounts of impurities present in experimental chemical fluids "used as received" have a drastic impact on the properties of the interface. Initial and equilibrium IFT are shown to be dramatically different, therefore it is important to be cautious of utilizing IFT values in numerical models. The study demonstrates the impact these variations in IFT have on relative permeability relationships by adopting a simple pore network model simulation.

Sensitivity Analysis of Interfacial Tension on Saturation and Relative Permeability Model Predictions

KAUST Repository

Abdallah, Wael

2011-05-18

Interfacial tension (IFT) measurements of Dodecane/brine systems at different concentrations and Dodecane/deionized water subject to different Dodecane purification cycles were taken over extended durations at room temperature and pressure to investigate the impact of aging. When a fresh droplet was formed, a sharp drop in IFT was observed assumed to be a result of intrinsic impurity adsorption at the interface. The subsequent measurements exhibited a prolonged equilibration period consistent with diffusion from the bulk phase to the interface. Our results indicate that minute amounts of impurities present in experimental chemical fluids "used as received" have a drastic impact on the properties of the interface. Initial and equilibrium IFT are shown to be dramatically different, therefore it is important to be cautious of utilizing IFT values in numerical models. The study demonstrates the impact these variations in IFT have on relative permeability relationships by adopting a simple pore network model simulation.

Modification of permeability of frog perineurium to [14C]-sucrose by stretch and hypertonicity

International Nuclear Information System (INIS)

Weerasuriya, A.; Rapoport, S.I.; Taylor, R.E.

1979-01-01

An in vitro method has been developed to determine quantitatively the permeability of the perineurium to radiotracers at room temperature. The permeability to [ 14 C]sucrose of the isolated perineurium of the sciatic nerve of the frog, Rana pipiens, was measured at rest length, when the perineurium was stretched and after the perineurium had been subjected to hypertonic treatment. Mean permeability at rest length was calculated to be 5.6 +- 0.27 (S.E.M., n=45)x10 -7 cm/sec, and both stretch and hypertonic treatment increased the permeability. A 10% stretch increased permeability reversibly, whereas a 20% stretch or immersion of the perineurium in a hypertonic bath increased permeability irreversibly. Altered permeability under these conditions might be related to changes in the ultrastructure of tight junctions in the perineurium. (Auth.)

Permeability log using new lifetime measurements

International Nuclear Information System (INIS)

Dowling, D.J.; Boyd, J.F.; Fuchs, J.A.

1975-01-01

Comparative measurements of thermal neutron decay time are obtained for a formation after irradiation with a pulsed neutron source. Chloride ions in formation fluids are concentrated by the electrosmosis effect using charged poles on a well logging sonde. The formation is irradiated with fast neutrons and a first comparative measure of the thermal neutron decay time or neutron lifetime is taken. The chloride ions are then dispersed by acoustic pumping with a magnetostrictive transducer. The formation is then again irradiated with fast neutrons and a comparative measure of neutron lifetime is taken. The comparison is a function of the variation in chloride concentration between the two measurements which is related to formation permeability

Microstructure-based characterization of permeability using a random walk model

International Nuclear Information System (INIS)

Chen, F F; Yang, Y S

2012-01-01

Quantitative transport properties of materials are analysed using a random walk model, based on the microscopic compositional distribution of compositions in the materials. A material sample is defined on a simple-cubic lattice, with volume fractions specified for each composition on every volume pixel (voxel). The quantitative relation between bulk permeability and fine-scale anisotropy is investigated by assuming fully anisotropic and fully isotropic voxel morphology. Such a study has prompted an analytic approximate formulation to predict bulk permeability range for a heterogeneous multi-component system that lacks detailed microstructure information. The numerical approach is verified on synthetic structures with known permeability. The analysis technique is applied to a real-world rock sample, as illustrated by a case study detailed in this paper. The investigations show that the bulk permeability is affected significantly by fine length scale anisotropy. (paper)

Experimental study on the soil structure and permeability in aerated zone at CIRP's field test site

International Nuclear Information System (INIS)

Du Zhongde; Zhao Yingjie; Guo Zhiming

2000-01-01

Measurement of soil grain and pore size distribution, observation of soil microstructure and permeability test are used to study soil structure and permeability. The results show that soil heterogeneity in vertical soil profile is much great. The mean heterogeneity coefficient is 14.7. The eccentric rate of saturated permeability coefficient in vertical and horizontal direction is from 0.65 to 1.00. The mean coefficient is 0.93. So the soil can be considered to be isotropic from the view point of the groundwater dynamics. The permeability coefficient has more difference in different soil layers. In vertical profile, the saturated permeability coefficient is relatively great in upper and under layers. It is relatively small in middle layers

Effect of Fluid Bypassing on the Experimentally Obtained Darcy and Non-Darcy Permeability Parameters of Ceramic Foam Filters

Science.gov (United States)

Akbarnejad, Shahin; Saffari Pour, Mohsen; Jonsson, Lage Tord Ingemar; Jönsson, Pӓr Göran

2017-02-01

Ceramic foam filters (CFFs) are used to remove solid particles and inclusions from molten metal. In general, molten metal which is poured on the top of a CFF needs to reach a certain height to build the required pressure (metal head) to prime the filter. To estimate the required metal head, it is necessary to obtain permeability coefficients using permeametry experiments. It has been mentioned in the literature that to avoid fluid bypassing, during permeametry, samples need to be sealed. However, the effect of fluid bypassing on the experimentally obtained pressure gradients seems not to be explored. Therefore, in this research, the focus was on studying the effect of fluid bypassing on the experimentally obtained pressure gradients as well as the empirically obtained Darcy and non-Darcy permeability coefficients. Specifically, the aim of the research was to investigate the effect of fluid bypassing on the liquid permeability of 30, 50, and 80 pores per inch (PPI) commercial alumina CFFs. In addition, the experimental data were compared to the numerically modeled findings. Both studies showed that no sealing results in extremely poor estimates of the pressure gradients and Darcy and non-Darcy permeability coefficients for all studied filters. The average deviations between the pressure gradients of the sealed and unsealed 30, 50, and 80 PPI samples were calculated to be 57.2, 56.8, and 61.3 pct. The deviations between the Darcy coefficients of the sealed and unsealed 30, 50, and 80 PPI samples found to be 9, 20, and 31 pct. The deviations between the non-Darcy coefficients of the sealed and unsealed 30, 50, and 80 PPI samples were calculated to be 59, 58, and 63 pct.

The influence of naphthenic acids and their fractions onto cell membrane permeability

Directory of Open Access Journals (Sweden)

Pavlović Ksenija

2015-01-01

Full Text Available The influence of naphthenic acids (NAs mixture and their narrow fractions (called NA pH 4, pH 8 and pH 10 onto permeability of beetroot cell membrane is examined. The results showed that the effect depends on treatment duration, concentration and NAs structure. Longer treatment of plant cell membranes with sodium naphthenate (Na-naph resulted in the increase of membrane permeability (e.g. 4-hour treatment with Na-naph (C=100 μmol L-1 increased membrane permeability about 3 times, while prolongation of treatment to 24 hour resulted in the 18 times increasing of the effect. NAs in the concentration range from 0.1 to 10 μmol L-1 does not change membrane permeability, while membrane permeability is increasing linearly with concentration increasing from 10-100 μmol L-1. The strongest effect expressed fraction pH 8, where bi- and tricyclic carboxylic acids are the most abundant. These structures are predominant in the total NAs mixture as well. Thereby could be explained their closest, but a little bit weaker effect, comparing to NAs present in fraction pH 8. The effect of NAs onto beetroot cell membrane is between the effects of anionic (SDS and LS and non-ionic surfactants (Triton X-100. [Projekat Ministarstva nauke Republike Srbije, br. 172006. i br. TR31036

Using artificial intelligence to predict permeability from petrographic data

Energy Technology Data Exchange (ETDEWEB)

Maqsood Ali; Adwait Chawathe [New Mexico Petroleum Recovery Research Centre (Mexico)

2000-10-01

Petrographic data collected during thin section analysis can be invaluable for understanding the factors that control permeability distribution. Reliable prediction of permeability is important for reservoir characterization. The petrographic elements (mineralogy, porosity types, cements and clays, and pore morphology) interact with each other uniquely to generate a specific permeability distribution. It is difficult to quantify accurately this interaction and its consequent effect on permeability, emphasizing the non-linear nature of the process. To capture these non-linear interactions, neural networks were used to predict permeability from petrographic data. The neural net was used as a multivariate correlative tool because of its ability to learn the non-linear relationships between multiple input and output variables. The study was conducted on the upper Queen formation called the Shattuck Member (Permian age). The Shattuck Member is composed of very fine-grained arkosic sandstone. The core samples were available from the Sulimar Queen and South Lucky Lake fields located in Chaves County, New Mexico. Nineteen petrographic elements were collected for each permeability value using a combined minipermeameter-petrographic technique. In order to reduce noise and overfitting the permeability model, these petrographic elements were screened, and their control (ranking) with respect to permeability was determined using fuzzy logic. Since the fuzzy logic algorithm provides unbiased ranking, it was used to reduce the dimensionality of the input variables. Based on the fuzzy logic ranking, only the most influential petrographic elements were selected as inputs for permeability prediction. The neural net was trained and tested using data from Well 1-16 in the Sulimar Queen field. Relying on the ranking obtained from the fuzzy logic analysis, the net was trained using the most influential three, five, and ten petrographic elements. A fast algorithm (the scaled conjugate

Effects of exogenous oxygen derived free radicals on myocardial capillary permeability, vascular tone, and incidence of ventricular arrhythmias in the canine heart

DEFF Research Database (Denmark)

Svendsen, Jesper Hastrup; Bjerrum, P J

1992-01-01

The aim was to examine the effects of exogenous oxygen derived free radicals on myocardial capillary permeability for a small hydrophilic indicator, postischaemic vascular tone, and the occurrence of arrhythmias in the canine heart in vivo.......The aim was to examine the effects of exogenous oxygen derived free radicals on myocardial capillary permeability for a small hydrophilic indicator, postischaemic vascular tone, and the occurrence of arrhythmias in the canine heart in vivo....

Ethamsylate and lung permeability in ventilated immature newborn rabbits.

Science.gov (United States)

Amato, M; Sun, B; Robertson, B

1994-01-01

The leakage of proteins in the immature neonatal lung can reduce the effect of exogenous surfactant. The effect of ethamsylate, a more specific prostaglandin inhibitor than indomethacin and aspirin-like drugs, on alveolar albumin leak was studied in a group of 27 immature newborn rabbits (gestational age 27 days). A pilot study was carried out using 4 animals and low-dose ethamsylate (10 mg/kg). A second group of animals (n = 12) received at birth, by intravenous injection, ethamsylate (50 mg/kg) and 10% human albumin (7 ml/kg). Animals not receiving ethamsylate (n = 11) served as control group. After 30 min of artificial ventilation with standard tidal volume (10 ml/kg) the lungs were lavaged and the amount of human albumin in lung lavage fluid was determined by immunodiffusion. No statistically significant differences were found in lung-thorax compliance and vascular to alveolar albumin leak between ethamsylate-treated animals and controls (p > 0.5). However, there was a statistically significant negative correlation between protein leak and lung compliance (r = -0.41; p ethamsylate administration on neonatal lung permeability in the immature neonate confirming that lung permeability is inversely related to compliance.

Wave transmission over permeable submerged breakwaters; Transmision del oleaje en rompeolas sumergidos permeables

Energy Technology Data Exchange (ETDEWEB)

Ruiz-y-Zurvia-Flores, Jaime Roberto; Fragoso-Sandoval, Lucio [Instituto Politecnico Nacional(Mexico)

2008-10-15

The permeable submerged breakwaters represent a coastal protection alternative, where some degree of wave energy transmission is acceptable. Such would be the case of tourist beach protection in Mexico. In previous researches, like those performed by D'Angremond et al. (1996), Seabrook and Hall (1998), and Briganti et al. (2003), the empirical formulas developed, give only some limited information over the spatial distribution of wave energy over the structure. Therefore, a decision was made to conduct a study on a reduced physical model of a permeable submerged breakwater based on the results presented by those researchers and with possible applications. Therefore this paper presents the development of a study of wave transmission over permeable submerged breakwaters performed in a reduced physical model of different sections of a submerged rockfill breakwater of the trapezoidal type. This was done in a narrow wave flume with a hydraulic irregular wave generator controlled by a computer that was used to generate and to reproduce different types of irregular waves to be used in the tests. It also has a wave meter with four sensors, and they are connected to a computer in order to process the wave data. The main objective of the study was to determine in an experimental way the influence of the several parameters of submerged breakwater over the wave transmission coefficient. Our experimental results were comparable to those obtained by D'Angremond et al. (1996) and Seabrook and Hall (1998). The results show that the sumerged breakwater parameters of most influence over the wave transmission coefficient were relative submergence and the relative width crest of the sumerged breakwater, and that the formula by Seabrook and Hall correlates best with our results. [Spanish] Los rompeolas sumergidos permeables representan actualmente una alternativa de proteccion de costas, donde un cierto grado de transmision de energia del oleaje es aceptable, como seria el

Apparent permeability of electrical steel under PWM magnetisation

International Nuclear Information System (INIS)

Moses, A.J.; Leicht, J.; Anderson, P.

2006-01-01

In recent years much attention has been paid to material performance under pulse width modulation (PWM) excitation conditions, which is of increasing importance to motor applications particularly in energy efficient variable speed drive systems. It is well known that in general, losses increase significantly with reducing modulation index, the increase depending on parameters such as silicon contents, thickness and grain size. The effect of the PWM waveform on permeability has attracted little attention until now. So in this paper its influence on the permeability of electrical steel is analysed and characterised. A prediction approach based on the permeability under sine wave excitation and total harmonic distortion is introduced which results in errors below 10% for non-electrical steel at 1.5 T

ADVANTAGES AND DISADVANTAGES OF MODERN LABORATORY MEASUREMENT OF THE COEFFICIENT OF PERMEABILITY FOR SOIL MATERIALS

OpenAIRE

Veinović, Želimir; Kovačević-Zelić, Biljana; Kvasnička, Predrag

2003-01-01

Permeability tests are one of the most often performed experiments in geotechnics. Conventional methods conducted by oedometer and triaxial apparatus have many disadvantages, the most significant being the test duration. As a consequence, errors in permeability measurements could occur. On the contrary, by applying modern flow-pump method, permeability measurements can be obtained much more rapidly. Moreover, the permeability/void ratio relation can be obtained by using adequate laboratory de...

Film Permeability Determination Using Static Permeability Cells

Science.gov (United States)

The permeability of tarps to soil fumigant pesticides varies depending on the active ingredient chemical: dimethyl disulfide (DMDS), methyl bromide, chloropicrin, or other. The diffusion rate can be represented by the mass transfer coefficient (MTC).

Permeability testing of biomaterial membranes

Energy Technology Data Exchange (ETDEWEB)

Dreesmann, L; Hajosch, R; Nuernberger, J Vaz; Schlosshauer, B [NMI Natural and Medical Sciences Institute at University Tuebingen, Markwiesenstr. 55, D-72770 Reutlingen (Germany); Ahlers, M [GELITA AG, Gammelsbacher Str. 2, D-69412 Eberbach (Germany)], E-mail: schlosshauer@nmi.de

2008-09-01

The permeability characteristics of biomaterials are critical parameters for a variety of implants. To analyse the permeability of membranes made from crosslinked ultrathin gelatin membranes and the transmigration of cells across the membranes, we combined three technical approaches: (1) a two-chamber-based permeability assay, (2) cell culturing with cytochemical analysis and (3) biochemical enzyme electrophoresis (zymography). Based on the diffusion of a coloured marker molecule in conjunction with photometric quantification, permeability data for a gelatin membrane were determined in the presence or absence of gelatin degrading fibroblasts. Cytochemical evaluation after cryosectioning of the membranes was used to ascertain whether fibroblasts had infiltrated the membrane inside. Zymography was used to investigate the potential release of proteases from fibroblasts, which are known to degrade collagen derivatives such as gelatin. Our data show that the diffusion equilibrium of a low molecular weight dye across the selected gelatin membrane is approached after about 6-8 h. Fibroblasts increase the permeability due to cavity formation in the membrane inside without penetrating the membrane for an extended time period (>21 days in vitro). Zymography indicates that cavity formation is most likely due to the secretion of matrix metalloproteinases. In summary, the combination of the depicted methods promises to facilitate a more rational development of biomaterials, because it provides a rapid means of determining permeability characteristics and bridges the gap between descriptive methodology and the mechanistic understanding of permeability alterations due to biological degradation.

Permeability testing of biomaterial membranes

International Nuclear Information System (INIS)

Dreesmann, L; Hajosch, R; Nuernberger, J Vaz; Schlosshauer, B; Ahlers, M

2008-01-01

The permeability characteristics of biomaterials are critical parameters for a variety of implants. To analyse the permeability of membranes made from crosslinked ultrathin gelatin membranes and the transmigration of cells across the membranes, we combined three technical approaches: (1) a two-chamber-based permeability assay, (2) cell culturing with cytochemical analysis and (3) biochemical enzyme electrophoresis (zymography). Based on the diffusion of a coloured marker molecule in conjunction with photometric quantification, permeability data for a gelatin membrane were determined in the presence or absence of gelatin degrading fibroblasts. Cytochemical evaluation after cryosectioning of the membranes was used to ascertain whether fibroblasts had infiltrated the membrane inside. Zymography was used to investigate the potential release of proteases from fibroblasts, which are known to degrade collagen derivatives such as gelatin. Our data show that the diffusion equilibrium of a low molecular weight dye across the selected gelatin membrane is approached after about 6-8 h. Fibroblasts increase the permeability due to cavity formation in the membrane inside without penetrating the membrane for an extended time period (>21 days in vitro). Zymography indicates that cavity formation is most likely due to the secretion of matrix metalloproteinases. In summary, the combination of the depicted methods promises to facilitate a more rational development of biomaterials, because it provides a rapid means of determining permeability characteristics and bridges the gap between descriptive methodology and the mechanistic understanding of permeability alterations due to biological degradation

Tomographic evidence for enhanced fracturing and permeability within the relatively aseismic Nemaha Fault Zone, Oklahoma

Science.gov (United States)

Stevens, N. T.; Keranen, K. M.; Lambert, C.

2017-12-01

Recent earthquakes in north central Oklahoma are dominantly hosted on unmapped basement faults away from and outside of the largest regional structure, the Nemaha Fault Zone (NFZ) [Lambert, 2016]. The NFZ itself remains largely aseismic, despite the presence of disposal wells and numerous faults. Here we present results from double-difference tomography using TomoDD [Zhang and Thurber, 2003] for the NFZ and the surrounding region, utilizing a seismic catalog of over 10,000 local events acquired by 144 seismic stations deployed between 2013 and 2017. Inversion results for shallow crustal depth, beneath the 2-3 km sedimentary cover, show compressional wavespeeds (Vp) of >6 km/sec and shear wavespeeds (Vs) >4 km/sec outside the NFZ, consistent with crystalline rock. Along the western margin of the NFZ, both Vp and Vs are reduced, and Vp/Vs gradients parallel the trend of major faults, suggesting enhanced fault density and potentially enhanced fluid pressure within the study region. Enhanced fracture density within the NFZ, and associated permeability enhancement, could reduce the effect of regional fluid pressurization from injection wells, contributing to the relative aseismicity of the NFZ.

Mechanisms of formation damage in matrix-permeability geothermal wells

Energy Technology Data Exchange (ETDEWEB)

Bergosh, J.L.; Wiggins, R.B.; Enniss, D.O.

1982-04-01

Tests were conducted to determine mechanisms of formation damage that can occur in matrix permeability geothermal wells. Two types of cores were used in the testing, actual cores from the East Mesa Well 78-30RD and cores from a fairly uniform generic sandstone formation. Three different types of tests were run. The East Mesa cores were used in the testing of the sensitivity of core to filtrate chemistry. The tests began with the cores exposed to simulated East Mesa brine and then different filtrates were introduced and the effects of the fluid contrast on core permeability were measured. The East Mesa cores were also used in the second series of tests which tested formation sandstone cores were used in the third test series which investigated the effects of different sizes of entrained particles in the fluid. Tests were run with both single-particle sizes and distributions of particle mixes. In addition to the testing, core preparation techniques for simulating fracture permeability were evaluated. Three different fracture formation mechanisms were identified and compared. Measurement techniques for measuring fracture size and permeability were also developed.

Permeability of sediment cores from methane hydrate deposit in the Eastern Nankai Trough, Japan

Science.gov (United States)

Konno, Y.; Yoneda, J.; Egawa, K.; Ito, T.; Jin, Y.; Kida, M.; Suzuki, K.; Nakatsuka, Y.; Nagao, J.

2013-12-01

Effective and absolute permeability are key parameters for gas production from methane-hydrate-bearing sandy sediments. Effective and/or absolute permeability have been measured using methane-hydrate-bearing sandy cores and clayey and silty cores recovered from Daini Atsumi Knoll in the Eastern Nankai Trough during the 2012 JOGMEC/JAPEX Pressure coring operation. Liquid-nitrogen-immersed cores were prepared by rapid depressurization of pressure cores recovered by a pressure coring system referred to as the Hybrid PCS. Cores were shaped cylindrically on a lathe with spraying of liquid nitrogen to prevent hydrate dissociation. Permeability was measured by a flooding test or a pressure relaxation method under near in-situ pressure and temperature conditions. Measured effective permeability of hydrate-bearing sediments is less than tens of md, which are order of magnitude less than absolute permeability. Absolute permeability of clayey cores is approximately tens of μd, which would perform a sealing function as cap rocks. Permeability reduction due to a swelling effect was observed for a silty core during flooding test of pure water mimicking hydrate-dissociation-water. Swelling effect may cause production formation damage especially at a later stage of gas production from methane hydrate deposits. This study was financially supported by the Research Consortium for Methane Hydrate Resources in Japan (MH21 Research Consortium) that carries out Japan's Methane Hydrate R&D Program conducted by the Ministry of Economy, Trade and Industry (METI).

Evaluation of the membrane permeability (PAMPA and skin) of benzimidazoles with potential cannabinoid activity and their relation with the Biopharmaceutics Classification System (BCS).

Science.gov (United States)

Alvarez-Figueroa, M Javiera; Pessoa-Mahana, C David; Palavecino-González, M Elisa; Mella-Raipán, Jaime; Espinosa-Bustos, Cristián; Lagos-Muñoz, Manuel E

2011-06-01

The permeability of five benzimidazole derivates with potential cannabinoid activity was determined in two models of membranes, parallel artificial membrane permeability assay (PAMPA) and skin, in order to study the relationship of the physicochemical properties of the molecules and characteristics of the membranes with the permeability defined by the Biopharmaceutics Classification System. It was established that the PAMPA intestinal absorption method is a good predictor for classifying these molecules as very permeable, independent of their thermodynamic solubility, if and only if these have a Log P(oct) value permeability is conditioned on the solubility of the molecule so that it can only serve as a model for classifying the permeability of molecules that possess high solubility (class I: high solubility, high permeability; class III: high solubility, low permeability).

The Effect Of Anisotropy In Formation Permeability On The Efficiency Of Cyclic Water Flooding

Directory of Open Access Journals (Sweden)

Al-Obaidi SH

2017-11-01

Full Text Available In oil industry one of the most worldwide used methods a among the hydrodynamic enhanced oil recovery methods is the water flooding including the cyclic water flooding. The efficiency of cyclic water flooding is affected by a number of geophysical and field technological factors. In this work and based on three-dimensional hydrodynamic simulation it is shown that anisotropy of formation permeability has significant effect on justification of the half-cycle time and the technological effectiveness of the method.

Measurement of HTO permeability of materials for protective appliances

International Nuclear Information System (INIS)

Yamamoto, H.; Tomooka, M.; Kato, S.; Murata, M.; Kinouchi, N.; Yamamoto, H.

1992-01-01

Tritiated water (HTO) vapor permeabilities were measured for plastic and rubber films used for protective appliances (suits, gloves, wrappings, etc.). The measurement data prove that polyehylene and butyl rubbers are materials suitable for HTO protective appliances with their lower permeability. The data also indicate that desiccating protective appliances before reuse is effective for restoring their original resistances to penetrating HTO vapor when they are repeatedly used. (author)

Permeability testing of fractures in climax stock granite at the Nevada Test Site

International Nuclear Information System (INIS)

Murray, W.A.

1980-01-01

Permeability tests conducted in the Climax stock granitic rock mass indicate that the bulk rock permeability can be highly variable. If moderately to highly fractured zones are encountered, the permeability values may lie in the range of 10 -4 to 10 -1 darcies. If, on the other hand, only intact rock or healed fractures are encountered, the permeability is found to be less than 10 -9 darcies. In order to assess the thermomechanical effect on fracture permeability, discrete fractures will be packed off and tested periodically throughout the thermal cycle caused by the emplacement of spent nuclear fuel in the Climax stock

Clear-cutting affects habitat connectivity for a forest amphibian by decreasing permeability to juvenile movements.

Science.gov (United States)

Popescu, Viorel D; Hunter, Malcolm L

2011-06-01

Conservation of forest amphibians is dependent on finding the right balance between management for timber production and meeting species' habitat requirements. For many pond-breeding amphibians, successful dispersal of the juvenile stage is essential for long-term population persistence. We investigated the influence of timber-harvesting practices on the movements of juvenile wood frogs (Lithobates sylvaticus). We used a chronosequence of stands produced by clear-cutting to evaluate how stand age affects habitat permeability to movements. We conducted experimental releases of juveniles in 2008 (n = 350) and 2009 (n = 528) in unidirectional runways in four treatments: mature forest, recent clearcut, 11-year-old, and 20-year-old regeneration. The runways were 50 x 2.5-m enclosures extending into each treatment, perpendicular to a distinct edge, with four tracking stations at 10, 20, 30, and 40 m from the edge. We recorded the number of animals reaching each tracking station, and the proportion of animals changing their direction of movement at each distance. We found that the mature forest was 3.1 and 3.7 times more permeable than the 11-year-old regeneration and the recent clearcut, respectively. Animals actively avoided open-canopy habitats and sharp edges; significantly more animals returned toward the closed-canopy forest at 0 m and 10 m in the less permeable treatments. There were no significant differences in habitat permeability between the mature forest and the 20-year-old regeneration. Our study is the first to directly assess habitat permeability to juvenile amphibian movement in relation to various forestry practices. We argue that habitat permeability at this scale is largely driven by the behavior of animals in relation to habitat disturbance and that caution needs to be used when using spatial modeling and expert-derived permeability values to assess connectivity of amphibian populations. The effects of clear-cutting on the migratory success of juvenile

Permeability of cork to gases.

Science.gov (United States)

Faria, David P; Fonseca, Ana L; Pereira, Helen; Teodoro, Orlando M N D

2011-04-27

The permeability of gases through uncompressed cork was investigated. More than 100 samples were assessed from different plank qualities to provide a picture of the permeability distribution. A novel technique based on a mass spectrometer leak detector was used to directly measure the helium flow through the central area of small disks 10 mm in diameter and 2 mm thick. The permeability for nitrogen, oxygen, and other gases was measured by the pressure rise technique. Boiled and nonboiled cork samples from different sections were evaluated. An asymmetric frequency distribution ranging 3 orders of magnitude (roughly from 1 to 1000 μmol/(cm·atm·day)) for selected samples without macroscopic defects was found, having a peak below 100 μmol/(cm·atm·day). Correlation was found between density and permeability: higher density samples tend to show lower permeability. However, boiled cork showed a mean lower permeability despite having a lower density. The transport mechanism of gases through cork was also examined. Calculations suggest that gases permeate uncompressed cork mainly through small channels between cells under a molecular flow regime. The diameter of such channels was estimated to be in the range of 100 nm, in agreement with the plasmodesmata size in the cork cell walls.

Retinal pathology is associated with increased blood-retina barrier permeability in a diabetic and hypercholesterolaemic pig model: Beneficial effects of the LpPLA2 inhibitor Darapladib.

Science.gov (United States)

Acharya, Nimish K; Qi, Xin; Goldwaser, Eric L; Godsey, George A; Wu, Hao; Kosciuk, Mary C; Freeman, Theresa A; Macphee, Colin H; Wilensky, Robert L; Venkataraman, Venkat; Nagele, Robert G

2017-05-01

Using a porcine model of diabetes mellitus and hypercholesterolaemia, we previously showed that diabetes mellitus and hypercholesterolaemia is associated with a chronic increase in blood-brain barrier permeability in the cerebral cortex, leading to selective binding of immunoglobulin G and deposition of amyloid-beta 1-42 peptide in pyramidal neurons. Treatment with Darapladib (GlaxoSmithKline, SB480848), an inhibitor of lipoprotein-associated phospholipase-A2, alleviated these effects. Here, investigation of the effects of chronic diabetes mellitus and hypercholesterolaemia on the pig retina revealed a corresponding increased permeability of the blood-retina barrier coupled with a leak of plasma components into the retina, alterations in retinal architecture, selective IgG binding to neurons in the ganglion cell layer, thinning of retinal layers due to cell loss and increased glial fibrillary acidic protein expression in Müller cells, all of which were curtailed by treatment with Darapladib. These findings suggest that chronic diabetes mellitus and hypercholesterolaemia induces increased blood-retina barrier permeability that may be linked to altered expression of blood-retina barrier-associated tight junction proteins, claudin and occludin, leading to structural changes in the retina consistent with diabetic retinopathy. Additionally, results suggest that drugs with vascular anti-inflammatory properties, such as Darapladib, may have beneficial effects on eye diseases strongly linked to vascular abnormalities such as diabetic retinopathy and age-related macular degeneration.

Influence of Cholesterol on the Oxygen Permeability of Membranes: Insight from Atomistic Simulations.

Science.gov (United States)

Dotson, Rachel J; Smith, Casey R; Bueche, Kristina; Angles, Gary; Pias, Sally C

2017-06-06

Cholesterol is widely known to alter the physical properties and permeability of membranes. Several prior works have implicated cell membrane cholesterol as a barrier to tissue oxygenation, yet a good deal remains to be explained with regard to the mechanism and magnitude of the effect. We use molecular dynamics simulations to provide atomic-resolution insight into the influence of cholesterol on oxygen diffusion across and within the membrane. Our simulations show strong overall agreement with published experimental data, reproducing the shapes of experimental oximetry curves with high accuracy. We calculate the upper-limit transmembrane oxygen permeability of a 1-palmitoyl,2-oleoylphosphatidylcholine phospholipid bilayer to be 52 ± 2 cm/s, close to the permeability of a water layer of the same thickness. With addition of cholesterol, the permeability decreases somewhat, reaching 40 ± 2 cm/s at the near-saturating level of 62.5 mol % cholesterol and 10 ± 2 cm/s in a 100% cholesterol mimic of the experimentally observed noncrystalline cholesterol bilayer domain. These reductions in permeability can only be biologically consequential in contexts where the diffusional path of oxygen is not water dominated. In our simulations, cholesterol reduces the overall solubility of oxygen within the membrane but enhances the oxygen transport parameter (solubility-diffusion product) near the membrane center. Given relatively low barriers to passing from membrane to membrane, our findings support hydrophobic channeling within membranes as a means of cellular and tissue-level oxygen transport. In such a membrane-dominated diffusional scheme, the influence of cholesterol on oxygen permeability is large enough to warrant further attention. Copyright © 2017 Biophysical Society. Published by Elsevier Inc. All rights reserved.

Effect of plate permeability on nonlinear stability of the asymptotic suction boundary layer.

Science.gov (United States)

Wedin, Håkan; Cherubini, Stefania; Bottaro, Alessandro

2015-07-01

The nonlinear stability of the asymptotic suction boundary layer is studied numerically, searching for finite-amplitude solutions that bifurcate from the laminar flow state. By changing the boundary conditions for disturbances at the plate from the classical no-slip condition to more physically sound ones, the stability characteristics of the flow may change radically, both for the linearized as well as the nonlinear problem. The wall boundary condition takes into account the permeability K̂ of the plate; for very low permeability, it is acceptable to impose the classical boundary condition (K̂=0). This leads to a Reynolds number of approximately Re(c)=54400 for the onset of linearly unstable waves, and close to Re(g)=3200 for the emergence of nonlinear solutions [F. A. Milinazzo and P. G. Saffman, J. Fluid Mech. 160, 281 (1985); J. H. M. Fransson, Ph.D. thesis, Royal Institute of Technology, KTH, Sweden, 2003]. However, for larger values of the plate's permeability, the lower limit for the existence of linear and nonlinear solutions shifts to significantly lower Reynolds numbers. For the largest permeability studied here, the limit values of the Reynolds numbers reduce down to Re(c)=796 and Re(g)=294. For all cases studied, the solutions bifurcate subcritically toward lower Re, and this leads to the conjecture that they may be involved in the very first stages of a transition scenario similar to the classical route of the Blasius boundary layer initiated by Tollmien-Schlichting (TS) waves. The stability of these nonlinear solutions is also investigated, showing a low-frequency main unstable mode whose growth rate decreases with increasing permeability and with the Reynolds number, following a power law Re(-ρ), where the value of ρ depends on the permeability coefficient K̂. The nonlinear dynamics of the flow in the vicinity of the computed finite-amplitude solutions is finally investigated by direct numerical simulations, providing a viable scenario for

An experimental study of relative permeability hysteresis, capillary trapping characteristics, and capillary pressure of CO2/brine systems at reservoir conditions

Science.gov (United States)

Akbarabadi, Morteza

We present the results of an extensive experimental study on the effects of hysteresis on permanent capillary trapping and relative permeability of CO2/brine and supercritical (sc)CO2+SO2/brine systems. We performed numerous unsteady- and steady-state drainage and imbibition full-recirculation flow experiments in three different sandstone rock samples, i.e., low and high-permeability Berea, Nugget sandstones, and Madison limestone carbonate rock sample. A state-of-the-art reservoir conditions core-flooding system was used to perform the tests. The core-flooding apparatus included a medical CT scanner to measure in-situ saturations. The scanner was rotated to the horizontal orientation allowing flow tests through vertically-placed core samples with about 3.8 cm diameter and 15 cm length. Both scCO2 /brine and gaseous CO2 (gCO2)/brine fluid systems were studied. The gaseous and supercritical CO2/brine experiments were carried out at 3.46 and 11 MPa back pressures and 20 and 55°C temperatures, respectively. Under the above-mentioned conditions, the gCO2 and scCO2 have 0.081 and 0.393 gr/cm3 densities, respectively. During unsteady-state tests, the samples were first saturated with brine and then flooded with CO2 (drainage) at different maximum flow rates. The drainage process was then followed by a low flow rate (0.375 cm 3/min) imbibition until residual CO2 saturation was achieved. Wide flow rate ranges of 0.25 to 20 cm3/min for scCO2 and 0.125 to 120 cm3min for gCO2 were used to investigate the variation of initial brine saturation (Swi) with maximum CO2 flow rate and variation of trapped CO2 saturation (SCO2r) with Swi. For a given Swi, the trapped scCO2 saturation was less than that of gCO2 in the same sample. This was attributed to brine being less wetting in the presence of scCO2 than in the presence of gCO 2. During the steady-state experiments, after providing of fully-brine saturated core, scCO2 was injected along with brine to find the drainage curve and as

Geothermal Permeability Enhancement - Final Report

Energy Technology Data Exchange (ETDEWEB)

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.

Fault reactivation by fluid injection considering permeability evolution in fault-bordering damage zones

Science.gov (United States)

Yang, Z.; Yehya, A.; Rice, J. R.; Yin, J.

2017-12-01

Earthquakes can be induced by human activity involving fluid injection, e.g., as wastewater disposal from hydrocarbon production. The occurrence of such events is thought to be, mainly, due to the increase in pore pressure, which reduces the effective normal stress and hence the strength of a nearby fault. Change in subsurface stress around suitably oriented faults at near-critical stress states may also contribute. We focus on improving the modeling and prediction of the hydro-mechanical response due to fluid injection, considering the full poroelastic effects and not solely changes in pore pressure in a rigid host. Thus we address the changes in porosity and permeability of the medium due to the changes in the local volumetric strains. Our results also focus on including effects of the fault architecture (low permeability fault core and higher permeability bordering damage zones) on the pressure diffusion and the fault poroelastic response. Field studies of faults have provided a generally common description for the size of their bordering damage zones and how they evolve along their direction of propagation. Empirical laws, from a large number of such observations, describe their fracture density, width, permeability, etc. We use those laws and related data to construct our study cases. We show that the existence of high permeability damage zones facilitates pore-pressure diffusion and, in some cases, results in a sharp increase in pore-pressure at levels much deeper than the injection wells, because these regions act as conduits for fluid pressure changes. This eventually results in higher seismicity rates. By better understanding the mechanisms of nucleation of injection-induced seismicity, and better predicting the hydro-mechanical response of faults, we can assess methodologies and injection strategies to avoid risks of high magnitude seismic events. Microseismic events occurring after the start of injection are very important indications of when injection

Permeability of salt-crystal interfaces to brine

International Nuclear Information System (INIS)

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

1982-06-01

To investigate the movement of brine along grain boundaries in polycrystalline salt, measurements have been made of the radial flow of brine through the interface between cylindrical salt crystals under axial stresses to 140 bar and temperatures to 80 0 C. For constant conditions, the total flow of brine showed a linear dependence on the logarithm of time, and the reciprocal permeability increased linearly with time. Loss of salt from the interface by pressure solution effects was more than enough to account for the decrease in the apparent thickness of the interface (i.e., that which may be estimated for an interface of the same permeability formed by plane parallel surfaces). This apparent thickness, initially as large as 10 μm, decreased to as little as 0.2 μm with exposure to stress and flowing brine. It decreased quickly with sudden increases in axial stress and usually increased, though not reversibly, with decreases in stress. The rate of increase in the reciprocal permeability with time was roughly proportional to the stress and to the square of the hydraulic pressure drop. Assuming similar apparent thicknesses for the grain boundaries in polycrystalline salt, permeabilities are predicted that are quite consistent with the low values reported for stressed core specimens

Drug-permeability and transporter assays in Caco-2 and MDCK cell lines.

Science.gov (United States)

Volpe, Donna A

2011-12-01

The human colon adenocarcinoma Caco-2 and Madin-Darby canine kidney epithelial cell lines provide in vitro tools to assess a drug's permeability and transporter interactions during discovery and development. The cells, when cultured on semiporous filters, form confluent monolayers that model the intestinal epithelial barrier for permeability, transporter and drug-interaction assays. The applications of these assays in pharmaceutical research include qualitative prediction and ranking of absorption, determining mechanism(s) of permeability, formulation effects on drug permeability, and the potential for transporter-mediated drug-drug interactions. This review focuses on recent examples of Caco-2 and Madin-Darby canine kidney cells assays for drug permeability including transfected and knock-down cells, miniaturization and automation, and assay combinations to better understand and predict intestinal drug absorption.

The effects of surface treatments on rapid chloride permeability tests

KAUST Repository

Yoon, Seyoon

2012-08-01

Surface treatments are commonly applied to improve the chloride resistance of concrete structures exposed to saline environments. Information on chloride ingress to surface-treated concrete is mostly provided by application of the rapid chloride permeability test (RCPT); this test is short in duration and provides rapid results. This study presents a numerical formulation, based on the extended Nernst-Plank/Poisson (NPP) equation, to model the effect of the surface treatment on a sample tested by RCPT. Predictions of the model are compared to experimental measurements. The simulations show that the results from RCPT, in terms of ionic profiles and measurement of the electric field, are dependent on the effectiveness of surface treatments. During RCPT, highly effective surface treatments cause both cations and anions to flocculate at the interface between the surface treatment and the concrete, creating a local electric field. Our numerical model includes these phenomena and presents a methodology to obtain more accurate diffusivities of the surface-treated- concrete from RCPT. © 2012 Elsevier B.V. All rights reserved.

The effects of surface treatments on rapid chloride permeability tests

KAUST Repository

Yoon, Seyoon; Oh, Sang-gyun; Ha, Juyoung; Monteiro, Paulo M.

2012-01-01

Surface treatments are commonly applied to improve the chloride resistance of concrete structures exposed to saline environments. Information on chloride ingress to surface-treated concrete is mostly provided by application of the rapid chloride permeability test (RCPT); this test is short in duration and provides rapid results. This study presents a numerical formulation, based on the extended Nernst-Plank/Poisson (NPP) equation, to model the effect of the surface treatment on a sample tested by RCPT. Predictions of the model are compared to experimental measurements. The simulations show that the results from RCPT, in terms of ionic profiles and measurement of the electric field, are dependent on the effectiveness of surface treatments. During RCPT, highly effective surface treatments cause both cations and anions to flocculate at the interface between the surface treatment and the concrete, creating a local electric field. Our numerical model includes these phenomena and presents a methodology to obtain more accurate diffusivities of the surface-treated- concrete from RCPT. © 2012 Elsevier B.V. All rights reserved.

A multi-state magnetic memory dependent on the permeability of Metglas

Science.gov (United States)

Petrie, J. R.; Wieland, K. A.; Timmerwilke, J. M.; Barron, S. C.; Burke, R. A.; Newburgh, G. A.; Burnette, J. E.; Fischer, G. A.; Edelstein, A. S.

2015-04-01

A three-state magnetic memory was developed based on differences in the magnetic permeability of a soft ferromagnetic media, Metglas 2826MB (Fe40Ni38Mo4B18). By heating bits of a 250 nm thick Metglas film with 70-100 mW of laser power, we were able to tune the local microstructure, and hence, the permeability. Ternary memory states were created by using lower laser power to enhance the initial permeability through localized atomic rearrangement and higher power to reduce the permeability through crystallization. The permeability of the bits was read by detecting variations in an external 32 Oe probe field within 10 μm of the media via a magnetic tunnel junction read head. Compared to data based on remanent magnetization, these multi-permeability bits have enhanced insensitivity to unexpected field and temperature changes. We found that data was not corrupted after exposure to fields of 1 T or temperatures of 423 K, indicating the effectiveness of this multi-state approach for safely storing large amounts of data.

A multi-state magnetic memory dependent on the permeability of Metglas

International Nuclear Information System (INIS)

Petrie, J. R.; Wieland, K. A.; Timmerwilke, J. M.; Burke, R. A.; Newburgh, G. A.; Fischer, G. A.; Edelstein, A. S.; Barron, S. C.; Burnette, J. E.

2015-01-01

A three-state magnetic memory was developed based on differences in the magnetic permeability of a soft ferromagnetic media, Metglas 2826MB (Fe 40 Ni 38 Mo 4 B 18 ). By heating bits of a 250 nm thick Metglas film with 70–100 mW of laser power, we were able to tune the local microstructure, and hence, the permeability. Ternary memory states were created by using lower laser power to enhance the initial permeability through localized atomic rearrangement and higher power to reduce the permeability through crystallization. The permeability of the bits was read by detecting variations in an external 32 Oe probe field within 10 μm of the media via a magnetic tunnel junction read head. Compared to data based on remanent magnetization, these multi-permeability bits have enhanced insensitivity to unexpected field and temperature changes. We found that data was not corrupted after exposure to fields of 1 T or temperatures of 423 K, indicating the effectiveness of this multi-state approach for safely storing large amounts of data

An efficient permeability scaling-up technique applied to the discretized flow equations

Energy Technology Data Exchange (ETDEWEB)

Urgelli, D.; Ding, Yu [Institut Francais du Petrole, Rueil Malmaison (France)

1997-08-01

Grid-block permeability scaling-up for numerical reservoir simulations has been discussed for a long time in the literature. It is now recognized that a full permeability tensor is needed to get an accurate reservoir description at large scale. However, two major difficulties are encountered: (1) grid-block permeability cannot be properly defined because it depends on boundary conditions; (2) discretization of flow equations with a full permeability tensor is not straightforward and little work has been done on this subject. In this paper, we propose a new method, which allows us to get around both difficulties. As the two major problems are closely related, a global approach will preserve the accuracy. So, in the proposed method, the permeability up-scaling technique is integrated in the discretized numerical scheme for flow simulation. The permeability is scaled-up via the transmissibility term, in accordance with the fluid flow calculation in the numerical scheme. A finite-volume scheme is particularly studied, and the transmissibility scaling-up technique for this scheme is presented. Some numerical examples are tested for flow simulation. This new method is compared with some published numerical schemes for full permeability tensor discretization where the full permeability tensor is scaled-up through various techniques. Comparing the results with fine grid simulations shows that the new method is more accurate and more efficient.

A fractal analytical model for the permeabilities of fibrous gas diffusion layer in proton exchange membrane fuel cells

International Nuclear Information System (INIS)

Xiao, Boqi; Fan, Jintu; Ding, Feng

2014-01-01

The study of water and gas transport through fibrous gas diffusion layer (GDL) is important to the optimization of proton exchange membrane fuel cells (PEMFCs). In this work, analytical models of dimensionless permeability, and water and gas relative permeabilities of fibrous GDL in PEMFCs are derived using fractal theory. In our models, the structure of fibrous GDL is characterized in terms of porosity, tortuosity fractal dimension (D T ), pore area fractal dimensions (d f ), water phase (d f,w ) and gas phase (d f,g ) fractal dimensions. The predicted dimensionless permeability, water and gas relative permeabilities based on the proposed models are in good agreement with experimental data and predictions of numerical simulations reported in the literature. The model reveals that, although water phase and gas phase fractal dimensions strongly depend on porosity, the water and gas relative permeabilities are independent of porosity and are a function of water saturation only. It is also shown that the dimensionless permeability decreases significantly with the increase of tortuosity fractal dimension. On the other hand, there is only a small decrease in the water and gas relative permeabilities when tortuosity fractal dimension increases. One advantage of the proposed analytical model is that it contains no empirical constant, which is normally required in past models

Magnetic field extraction of trap-based electron beams using a high-permeability grid

International Nuclear Information System (INIS)

Hurst, N. C.; Danielson, J. R.; Surko, C. M.

2015-01-01

A method to form high quality electrostatically guided lepton beams is explored. Test electron beams are extracted from tailored plasmas confined in a Penning-Malmberg trap. The particles are then extracted from the confining axial magnetic field by passing them through a high magnetic permeability grid with radial tines (a so-called “magnetic spider”). An Einzel lens is used to focus and analyze the beam properties. Numerical simulations are used to model non-adiabatic effects due to the spider, and the predictions are compared with the experimental results. Improvements in beam quality are discussed relative to the use of a hole in a high permeability shield (i.e., in lieu of the spider), and areas for further improvement are described

Realizability of metamaterials with prescribed electric permittivity and magnetic permeability tensors

International Nuclear Information System (INIS)

Milton, Graeme W

2010-01-01

We show that any pair of real symmetric tensors ε and μ can be realized as the effective electric permittivity and effective magnetic permeability of a metamaterial at a given fixed frequency. The construction starts with two extremely low-loss metamaterials, with arbitrarily small microstructure, whose existence is ensured by the work of Bouchitte and Bourel and Bouchitte and Schweizer: one having, at the given frequency, a permittivity tensor with exactly one negative eigenvalue, and a positive permeability tensor; and the other having a positive permittivity tensor, and a permeability tensor having exactly one negative eigenvalue. To achieve the desired effective properties, these materials are laminated together in a hierarchical multiple rank laminate structure, with widely separated length scales, and varying directions of lamination, but with the largest length scale still much shorter than the wavelengths and attenuation lengths in the macroscopic effective medium.

Persistence of aquatic insects across managed landscapes: effects of landscape permeability on re-colonization and population recovery

NARCIS (Netherlands)

Galic, N.; Hengeveld, G.M.; Van den Brink, P.J.; Schmolke, A.; Thorbek, P.; Bruns, E.; Baveco, J.M.

2013-01-01

Human practices in managed landscapes may often adversely affect aquatic biota, such as aquatic insects. Dispersal is often the limiting factor for successful re-colonization and recovery of stressed habitats. Therefore, in this study, we evaluated the effects of landscape permeability, assuming a

Bronchoalveolar permeability changes in rats inhaling gas/particle combinations during rest or exercise

International Nuclear Information System (INIS)

Bhalla, D.K.; Phalen, R.F.; Mannix, R.C.; Lavan, S.M.; Crocker, T.T.

1986-01-01

Bronchoalveolar (BA) injury in rats exposed at rest or exercise to air pollutants was studied by changes in epithelial permeability. Rats exposed to air, single gases or pollutant combinations were anesthetized, tracheostomized, and placed on an incline. /sup 99m/Tc-DTPA was delivered directly to a major bronchus. Radioactivity measurements were made on blood samples collected during first 10 min. Exposure of resting rats to 0.6 ppm O 3 increased BA permeability just after exposure, but it was normal 24 hrs later; in exercising rats the increase was greater than in rats exposed at rest, and it persisted up to 24 hrs. NO 2 at 6 ppm did not affect permeability. Exposure of resting rats to 2.5 ppm NO 2 + 0.6 ppm O 3 only increased permeability right after the exposure, but in exercising rats this exposure resulted in a greater permeability which remained elevated up to 24 hrs. Exposure of exercising rats to 0.8 ppm O 3 + 10 ppm HCHO increased permeability. Exposure of resting rats to an atmosphere of 0.6 ppm O 3 + 2.5 ppm NO 2 + 5 ppm SO 2 + 1 mg/m 3 sulfates of ferric, ammonium and manganese also produced an increase in permeability that persisted up to 24 hrs. The results suggest potentiation of the pollutant effects by exercise, but there is no indication of synergistic effect of pollutant combinations on BA permeability

A study on the water permeability of concrete structures

International Nuclear Information System (INIS)

Loadsman, R.V.C.; Acres, D.H.; Stokes, C.J.; Wadeson, L.

1988-03-01

This report forms part of the DoE's research programme on the disposal of nuclear waste. The information available on the permeability of concrete and the effects of various factors on this value are reviewed. The effect of defects on the overall permeability of concrete structures is examined and the recorded performance of a range of existing concrete structures is considered with identification of some of the factors that are significant in practice. Deficiencies in the information available on this subject are identified and recommendations for further work are made including a list of structures suitable for future monitoring. (author)

Permeability computation on a REV with an immersed finite element method

International Nuclear Information System (INIS)

Laure, P.; Puaux, G.; Silva, L.; Vincent, M.

2011-01-01

An efficient method to compute permeability of fibrous media is presented. An immersed domain approach is used to represent the porous material at its microscopic scale and the flow motion is computed with a stabilized mixed finite element method. Therefore the Stokes equation is solved on the whole domain (including solid part) using a penalty method. The accuracy is controlled by refining the mesh around the solid-fluid interface defined by a level set function. Using homogenisation techniques, the permeability of a representative elementary volume (REV) is computed. The computed permeabilities of regular fibre packings are compared to classical analytical relations found in the bibliography.

Permeable treatment wall design and cost analysis

International Nuclear Information System (INIS)

Manz, C.; Quinn, K.

1997-01-01

A permeable treatment wall utilizing the funnel and gate technology has been chosen as the final remedial solution for one industrial site, and is being considered at other contaminated sites, such as a closed municipal landfill. Reactive iron gates will be utilized for treatment of chlorinated VOCs identified in the groundwater. Alternatives for the final remedial solution at each site were evaluated to achieve site closure in the most cost effective manner. This paper presents the remedial alternatives and cost analyses for each site. Several options are available at most sites for the design of a permeable treatment wall. Our analysis demonstrates that the major cost factor's for this technology are the design concept, length, thickness, location and construction methods for the reactive wall. Minimizing the amount of iron by placement in the most effective area and construction by the lowest cost method is critical to achieving a low cost alternative. These costs dictate the design of a permeable treatment wall, including selection of a variety of alternatives (e.g., a continuous wall versus a funnel and gate system, fully penetrating gates versus partially penetrating gates, etc.). Selection of the appropriate construction methods and materials for the site can reduce the overall cost of the wall

The Permeability of Rubble Mound Breakwaters

DEFF Research Database (Denmark)

Williams, A.F.; Burcharth, H. F.; Adel, H. den

1992-01-01

. A new series of tests designed to test for deviations from the Forchheimer equation and investigate the effects of material shape are described. While no evidence can be found to indicate a deviation from the Forchheimer equation a dependency of permeability and the surface roughness the material...

Gut permeability is related to body weight, fatty liver disease, and insulin resistance in obese individuals undergoing weight reduction.

Science.gov (United States)

Damms-Machado, Antje; Louis, Sandrine; Schnitzer, Anna; Volynets, Valentina; Rings, Andreas; Basrai, Maryam; Bischoff, Stephan C

2017-01-01

Obesity and associated metabolic disorders are related to impairments of the intestinal barrier. We examined lactulose:mannitol (Lac:Man) permeability in obese individuals with and without liver steatosis undergoing a weight-reduction program to test whether an effective weight-loss program improves gut barrier function and whether obese patients with or without liver steatosis differ in this function. Twenty-seven adult, nondiabetic individuals [mean ± SD body mass index (BMI; in kg/m 2 ): 43.7 ± 5.2; 78% with moderate or severe liver steatosis] were included in the follow-up intervention study (n = 13 by month 12). All patients reduced their weight to a mean ± SD BMI of 36.4 ± 5.1 within 12 mo. We assessed barrier functions by the oral Lac:Man and the fecal zonulin tests. Insulin resistance was assessed by the homeostatic model assessment index (HOMA), and liver steatosis by sonography and the fatty liver index (FLI). The Lac:Man ratio and circulating interleukin (IL) 6 concentration decreased during intervention from 0.080 (95% CI: 0.073, 0.093) to 0.027 (95% CI: 0.024, 0.034; P < 0.001) and from 4.2 ± 1.4 to 2.8 ± 1.6 pg/mL (P < 0.01), respectively. At study start, the Lac:Man ratio was higher in patients with moderate or severe steatosis than in those without any steatosis (P < 0.001). The Lac:Man ratio tended to correlate with HOMA (ρ = 0.55, P = 0.052), which correlated with FLI (ρ = 0.75, P < 0.01). A multiple-regression analysis led to a final model explaining FLI best through BMI, waist circumference, and the Lac:Man ratio. Intestinal permeability is increased in obese patients with steatosis compared with obese patients without. The increased permeability fell to within the previously reported normal range after weight reduction. The data suggest that a leaky gut barrier is linked with liver steatosis and could be a new target for future steatosis therapies. This trial was registered at clinicaltrials.gov as NCT01344525. © 2017 American Society

A numerical approach for assessing effects of shear on equivalent permeability and nonlinear flow characteristics of 2-D fracture networks

Science.gov (United States)

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

2018-01-01

Hydro-mechanical properties of rock fractures are core issues for many geoscience and geo-engineering practices. Previous experimental and numerical studies have revealed that shear processes could greatly enhance the permeability of single rock fractures, yet the shear effects on hydraulic properties of fractured rock masses have received little attention. In most previous fracture network models, single fractures are typically presumed to be formed by parallel plates and flow is presumed to obey the cubic law. However, related studies have suggested that the parallel plate model cannot realistically represent the surface characters of natural rock fractures, and the relationship between flow rate and pressure drop will no longer be linear at sufficiently large Reynolds numbers. In the present study, a numerical approach was established to assess the effects of shear on the hydraulic properties of 2-D discrete fracture networks (DFNs) in both linear and nonlinear regimes. DFNs considering fracture surface roughness and variation of aperture in space were generated using an originally developed code DFNGEN. Numerical simulations by solving Navier-Stokes equations were performed to simulate the fluid flow through these DFNs. A fracture that cuts through each model was sheared and by varying the shear and normal displacements, effects of shear on equivalent permeability and nonlinear flow characteristics of DFNs were estimated. The results show that the critical condition of quantifying the transition from a linear flow regime to a nonlinear flow regime is: 10-4 〈 J hydraulic gradient. When the fluid flow is in a linear regime (i.e., J reduce the equivalent permeability significantly in the orientation perpendicular to the sheared fracture as much as 53.86% when J = 1, shear displacement Ds = 7 mm, and normal displacement Dn = 1 mm. By fitting the calculated results, the mathematical expression for δ2 is established to help choose proper governing equations when

Improvements in scaling of counter-current imbibition recovery curves using a shape factor including permeability anisotropy

Science.gov (United States)

Abbasi, Jassem; Sarafrazi, Shiva; Riazi, Masoud; Ghaedi, Mojtaba

2018-02-01

Spontaneous imbibition is the main oil production mechanism in the water invaded zone of a naturally fractured reservoir (NFR). Different scaling equations have been presented in the literature for upscaling of core scale imbibition recovery curves to field scale matrix blocks. Various scale dependent parameters such as gravity effects and boundary influences are required to be considered in the upscaling process. Fluid flow from matrix blocks to the fracture system is highly dependent on the permeability value in the horizontal and vertical directions. The purpose of this study is to include permeability anisotropy in the available scaling equations to improve the prediction of imbibition assisted oil production in NFRs. In this paper, a commercial reservoir simulator was used to obtain imbibition recovery curves for different scenarios. Then, the effect of permeability anisotropy on imbibition recovery curves was investigated, and the weakness of the existing scaling equations for anisotropic rocks was demonstrated. Consequently, an analytical shape factor was introduced that can better scale all the curves related to anisotropic matrix blocks.

Evolution of permeability in siliceous rocks induced by mineral dissolution and precipitation

International Nuclear Information System (INIS)

Yasuhara, Hideaki; Kinoshita, Naoki; Kurikami, Hiroshi; Nakashima, Shinichiro; Kishida, Kiyoshi

2007-01-01

A conceptual model is presented to follow the evolution of permeability in siliceous rocks mediated by pressure solution. Specifically, the main minerals of siliceous rocks that are quartz, cristobalite, and amorphous silica, are focused to examine differences of the permeability evolutions among them at effective pressures of 1, 5, and 10 MPa, and temperatures of 20 and 90degC. The rates and magnitudes of permeability reduction increase with increases of the pressures and temperatures applied. Ultimate permeabilities reduced by the order of 90 % at the completion of dissolution-mediated compaction at 10 MPa and 90degC. Precipitation may augment more degradation of flow transport in time. (author)

Microfluidic passive permeability assay using nanoliter droplet interface lipid bilayers.

Science.gov (United States)

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

2013-11-21

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

An integrated approach to permeability modeling using micro-models

Energy Technology Data Exchange (ETDEWEB)

Hosseini, A.H.; Leuangthong, O.; Deutsch, C.V. [Society of Petroleum Engineers, Canadian Section, Calgary, AB (Canada)]|[Alberta Univ., Edmonton, AB (Canada)

2008-10-15

An important factor in predicting the performance of steam assisted gravity drainage (SAGD) well pairs is the spatial distribution of permeability. Complications that make the inference of a reliable porosity-permeability relationship impossible include the presence of short-scale variability in sand/shale sequences; preferential sampling of core data; and uncertainty in upscaling parameters. Micro-modelling is a simple and effective method for overcoming these complications. This paper proposed a micro-modeling approach to account for sampling bias, small laminated features with high permeability contrast, and uncertainty in upscaling parameters. The paper described the steps and challenges of micro-modeling and discussed the construction of binary mixture geo-blocks; flow simulation and upscaling; extended power law formalism (EPLF); and the application of micro-modeling and EPLF. An extended power-law formalism to account for changes in clean sand permeability as a function of macroscopic shale content was also proposed and tested against flow simulation results. There was close agreement between the model and simulation results. The proposed methodology was also applied to build the porosity-permeability relationship for laminated and brecciated facies of McMurray oil sands. Experimental data was in good agreement with the experimental data. 8 refs., 17 figs.

Effect of age of permeable pavements on their infiltration function

NARCIS (Netherlands)

Boogaard, Floris; Lucke, Terry; Beecham, Simon

This study describes field investigations designed to compare the infiltration capacities of 55 permeable pavement systems installed in the Netherlands and in Australia. The ages of the pavements varied from 1 to 12 years. Using infiltrometer testing, the performance of the pavements has been

Three-Dimensional poroelastic effects during hydraulic fracturing in permeable rocks

DEFF Research Database (Denmark)

Salimzadeh, Saeed; Paluszny, Adriana; Zimmerman, Robert W.

2017-01-01

A fully coupled three-dimensional finite-element model for hydraulic fractures in permeable rocks is presented, and used to investigate the ranges of applicability of the classical analytical solutions that are known to be valid in limiting cases. This model simultaneously accounts for fluid flow...

Effect of age of permeable pavements on their infiltration function

NARCIS (Netherlands)

Terry Lucke; ir. Floris Boogaard; Simon Beecham

2013-01-01

This study describes field investigations designed to compare the infiltration capacities of 55 permeable pavement systems installed in the Netherlands and in Australia. The ages of the pavements varied from 1 to 12 years. Using infiltrometer testing, the performance of the pavements has been

EDZ and permeability in clayey rocks

International Nuclear Information System (INIS)

Levasseur, Severine; Collin, Frederic; Charlier, Robert; Besuelle, Pierre; Chambon, Rene; Viggiani, Cino

2010-01-01

Document available in extended abstract form only. Deep geological layers are being considered as potential host rocks for the high level radioactivity waste disposals. During drilling in host rocks, an excavated damaged zone - EDZ is created. The fluid transmissivity may be modified in this damaged zone. This paper deals with the permeability evolution in relation with diffuse and/or localized crack propagation in the material. We mainly focus on argillaceous rocks and on some underground laboratories: Mol URL in Boom clay, Bure URL in Callovo-Oxfordian clay and Mont-Terri URL in Opalinus clay. First, observations of damage around galleries are summarized. Structure of damage in localized zone or in fracture has been observed at underground gallery scale within the excavation damaged zone (EDZ). The first challenge for a correct understanding of all the processes occurring within the EDZ is the characterization at the laboratory scale of the damage and localization processes. The observation of the initiation and propagation of the localized zones needs for advanced techniques. X-ray tomography is a non-destructive imaging technique that allows quantification of internal features of an object in 3D. If mechanical loading of a specimen is applied inside a X-ray CT apparatus, successive 3D images at different loading steps show the evolution of the specimen. However, in general volumetric strain in a shear band is small compared to the shear strain and, unfortunately, in tomographic images grey level is mainly sensitive to the local mass density field. Such a limitation has been recently overcome by complementing X-ray tomography with 3D Volumetric Digital Image Correlation (V-DIC) which allows the determination of the full strain tensor field. Then it is possible to further explore the progression of localized deformation in the specimen. The second challenge is the robust modelling of the strain localized process. In fact, modelling the damage process with finite

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

Energy Technology Data Exchange (ETDEWEB)

Alves, Vinicius M. [Laboratory of Molecular Modeling and Design, Faculty of Pharmacy, Federal University of Goiás, Goiânia, GO 74605-220 (Brazil); Laboratory for Molecular Modeling, Division of Chemical Biology and Medicinal Chemistry, Eshelman School of Pharmacy, University of North Carolina, Chapel Hill, NC 27599 (United States); Muratov, Eugene [Laboratory for Molecular Modeling, Division of Chemical Biology and Medicinal Chemistry, Eshelman School of Pharmacy, University of North Carolina, Chapel Hill, NC 27599 (United States); Laboratory of Theoretical Chemistry, A.V. Bogatsky Physical–Chemical Institute NAS of Ukraine, Odessa 65080 (Ukraine); Fourches, Denis [Laboratory for Molecular Modeling, Division of Chemical Biology and Medicinal Chemistry, Eshelman School of Pharmacy, University of North Carolina, Chapel Hill, NC 27599 (United States); Strickland, Judy; Kleinstreuer, Nicole [ILS/Contractor supporting the NTP Interagency Center for the Evaluation of Alternative Toxicological Methods (NICEATM), P.O. Box 13501, Research Triangle Park, NC 27709 (United States); Andrade, Carolina H. [Laboratory of Molecular Modeling and Design, Faculty of Pharmacy, Federal University of Goiás, Goiânia, GO 74605-220 (Brazil); Tropsha, Alexander, E-mail: alex_tropsha@unc.edu [Laboratory for Molecular Modeling, Division of Chemical Biology and Medicinal Chemistry, Eshelman School of Pharmacy, University of North Carolina, Chapel Hill, NC 27599 (United States)

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

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

International Nuclear Information System (INIS)

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

2015-01-01

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 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 2 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 sensitization and

Effect of ionising radiation exposure on structure and permeability of epithelial junctions in rat ileum

International Nuclear Information System (INIS)

Lebrum, F.; Dublineau, I.; Grison, S.; Strup, C.; Griffiths, N.M.

2002-01-01

Exposure of the digestive tract to ionising radiation results in both morphological and functional alterations of the small intestine. However little is known about the effect of irradiation on the junctions playing a major role in the maintenance of epithelial barrier integrity. Thus the aim of this study was to investigate, in rat ileum, the effect of radiation exposure on the permeability of the epithelial barrier in parallel with the localization of certain inter- and intra-cellular proteins of tight and adherent junctions

Defining clogging potential for permeable concrete.

Science.gov (United States)

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

2018-08-15

Permeable concrete is used to reduce urban flooding as it allows water to flow through normally impermeable infrastructure. It is prone to clogging by particulate matter and predicting the long-term performance of permeable concrete is challenging as there is currently no reliable means of characterising clogging potential. This paper reports on the performance of a range of laboratory-prepared and commercial permeable concretes, close packed glass spheres and aggregate particles of varying size, exposed to different clogging methods to understand this phenomena. New methods were developed to study clogging and define clogging potential. The tests involved applying flowing water containing sand and/or clay in cycles, and measuring the change in permeability. Substantial permeability reductions were observed in all samples, particularly when exposed to sand and clay simultaneously. Three methods were used to define clogging potential based on measuring the initial permeability decay, half-life cycle and number of cycles to full clogging. We show for the first time strong linear correlations between these parameters for a wide range of samples, indicating their use for service-life prediction. Copyright © 2018 Elsevier Ltd. All rights reserved.

Use of swelling clays to reduce permeability and its potential application to nuclear waste repository sealing

International Nuclear Information System (INIS)

Moore, D.E.; Morrow, C.A.; Byerlee, J.D.

1982-01-01

The injection of swelling-clay slurries into joints or faults at a deep-burial nuclear waste disposal site may result in signficant permeability reductions for the effective containment of radioactive wastes. In an experiment conducted to illustrate the permeability change accompanying clay swelling, a coarse stone with interconnected pore spaces was injected with a clay-electrolyte slurry, modelling the pressure-grouting of a fractured repository rock. Subsequently, solutions with lower electroylte concentrations were driven through the clay-filled stone, corresponding to migration of lower salinity ground-waters through the clay-grouted fracture. The initial injection procedure reduced the permeability of the stone from 1--10 darcies to 700 nanodarcies; the changes in solution composition decreased permeability by more than 2 additional orders of magnitude to 3 nanodarcies. For application at a nuclear waste repository, the electrolyte concentration of the injected clay slurry should be made higher than that of the ground-water in the host rock. Subesquent interaction of the ground-water with the clays would initiate swelling and create the additional, post-injection permeability reductions that may be important in preventing the escape of buried radioactive wastes. The measured permeability of the clay filling is considerably lower than that of cement tested for borehole plugging. Clays also have the advantage over cement and chemical grouts in that they are geologically stable at relatively low temperatures and have a high capacity for radionuclide adsorption

The solubility-permeability interplay in using cyclodextrins as pharmaceutical solubilizers: mechanistic modeling and application to progesterone.

Science.gov (United States)

Dahan, Arik; Miller, Jonathan M; Hoffman, Amnon; Amidon, Gregory E; Amidon, Gordon L

2010-06-01

A quasi-equilibrium mass transport analysis has been developed to quantitatively explain the solubility-permeability interplay that exists when using cyclodextrins as pharmaceutical solubilizers. The model considers the effects of cyclodextrins on the membrane permeability (P(m)) as well as the unstirred water layer (UWL) permeability (P(aq)), to predict the overall effective permeability (P(eff)) dependence on cyclodextrin concentration (C(CD)). The analysis reveals that: (1) UWL permeability markedly increases with increasing C(CD) since the effective UWL thickness quickly decreases with increasing C(CD); (2) membrane permeability decreases with increasing C(CD), as a result of the decrease in the free fraction of drug; and (3) since P(aq) increases and P(m) decreases with increasing C(CD), the UWL is effectively eliminated and the overall P(eff) tends toward membrane control, that is, P(eff) approximately P(m) above a critical C(CD). Application of this transport model enabled excellent quantitative prediction of progesterone P(eff) as a function of HP beta CD concentrations in PAMPA assay, Caco-2 transepithelial studies, and in situ rat jejunal-perfusion model. This work demonstrates that when using cyclodextrins as pharmaceutical solubilizers, a trade-off exists between solubility increase and permeability decrease that must not be overlooked; the transport model presented here can aid in striking the appropriate solubility-permeability balance in order to achieve optimal overall absorption. (c) 2009 Wiley-Liss, Inc. and the American Pharmacists Association

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

Science.gov (United States)

Toramaru, A.; Yamauchi, S.

2012-04-01

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

Enhanced CAH dechlorination in a low permeability, variably-saturated medium

Science.gov (United States)

Martin, J.P.; Sorenson, K.S.; Peterson, L.N.; Brennan, R.A.; Werth, C.J.; Sanford, R.A.; Bures, G.H.; Taylor, C.J.; ,

2002-01-01

An innovative pilot-scale field test was performed to enhance the anaerobic reductive dechlorination (ARD) of chlorinated aliphatic hydrocarbons (CAHs) in a low permeability, variably-saturated formation. The selected technology combines the use of a hydraulic fracturing (fracking) technique with enhanced bioremediation through the creation of highly-permeable sand- and electron donor-filled fractures in the low permeability matrix. Chitin was selected as the electron donor because of its unique properties as a polymeric organic material and based on the results of lab studies that indicated its ability to support ARD. The distribution and impact of chitin- and sand-filled fractures to the system was evaluated using hydrologic, geophysical, and geochemical parameters. The results indicate that, where distributed, chitin favorably impacted redox conditions and supported enhanced ARD of CAHs. These results indicate that this technology may be a viable and cost-effective approach for remediation of low-permeability, variably saturated systems.

Measuring the permeability of Eleana argillite from area 17, Nevada Test Site, using the transient method

International Nuclear Information System (INIS)

Lin, W.

1978-01-01

Using the transient method, we determine the permeability of high-quartz Eleana argillite from the Nevada Test Site as a function of effective pressure. By comparing calculated and observed pressure decay in the upstream reservoir, we have determined the permeability of intact and fractured specimens at effective pressures ranging from 1.0 to 24.0 MPa. Over this pressure range, Eleana argillite has a low permeability (10 -16 to 10 -19 cm 2 ) when intact and a higher permeability (10 -12 to 10 -17 cm 2 ) with one induced through-going fracture

Dual Identity and Prejudice: The Moderating Role of Group Boundary Permeability

Science.gov (United States)

Shi, Yuanyuan; Dang, Jianning; Zheng, Wenwen; Liu, Li

2017-01-01

Past work suggested that dual identity was effective to reduce prejudice. This study extended research on dual identity and prejudice by identifying a boundary condition in this relationship, that is, group permeability. In Study 1, we replicated previous studies with Chinese individuals and found that inducing dual identity (emphasizing subgroup differences and a common nation identity), compared to the control condition, decreased the urban residents’ prejudice against rural-to-urban migrants. In Study 2, we manipulated the group boundary permeability using the Hukou system reform, and found that when the group boundary was permeable, dual identity was effective in reducing prejudice against rural-to-urban migrants. However, this effect vanished in the condition where the group boundary was impermeable. These results point to the importance of inducing dual identity under specific conditions for research on decreasing prejudice. Some practical implications of the findings for urbanization and immigration are discussed. PMID:28261130

Water-pipe smoking effects on pulmonary permeability using technetium-99m DTPA inhalation scintigraphy

International Nuclear Information System (INIS)

Aydin, A.; Durak, H.; Ucan, E.S.; Kaya, G.C.; Ceylan, E.; Kiter, G.

2004-01-01

Although extensive work has been done on cigarette smoking and its effects on pulmonary function, there are limited number of studies on water-pipe smoking. The effects of water-pipe smoking on health are not widely investigated. The aim of this study was to determine the effects of water-pipe smoking on pulmonary permeability. Technetium-99m DTPA inhalation scintigraphy was performed on 14 water-pipe smoker volunteers (all men, mean age 53.7±9.8) and 11 passive smoker volunteers (1 woman, 10 men, mean age 43.8±12). Clearance half-time (T 1/2) was calculated by placing a monoexponential fit on the time activity curves. Penetration index (PI) of the radioaerosol was also calculated. PI was 0.58±0.14 and 0.50±0.12 for water-pipe smokers (WPS) and passive smokers (PS) respectively. T 1/2 of peripheral lung was 57.3±12.7 and 64.6±13.2 min, central airways was 55.8±23.5 and 80.1±35.2 min for WPS and PS, respectively (p≤0.05). Forced expiratory volume in one second/forced vital capacity (FEV 1 /FVC)% was 82.1±8.5 (%) and 87.7±6.5 (%) for WPS and PS, respectively (0.025< p≤0.05). We suggest that water-pipe smoking effects pulmonary epithelial permeability more than passive smoking. Increased central mucociliary clearance in water-pipe smoking may be due to preserved humidity of the airway tracts. (author)

Quantifying porosity, compressibility and permeability in Shale

DEFF Research Database (Denmark)

Mbia, Ernest Ncha; Fabricius, Ida Lykke; Frykman, Peter

strain data. We found that Kozeny's modelled permeability fall in the same order of magnitude with measured permeability for shale rich in kaolinite but overestimates permeability by two to three orders of magnitudes for shale with high content of smectite. The empirical Yang and Aplin model gives good...... permeability estimate comparable to the measured one for shale rich in smectite. This is probably because Yang and Aplin model was calibrated in London clay which is rich in smectite....

Urban evaporation rates for water-permeable pavements.

Science.gov (United States)

Starke, P; Göbel, P; Coldewey, W G

2010-01-01

In urban areas the natural water balance is disturbed. Infiltration and evaporation are reduced, resulting in a high surface runoff and a typical city climate, which can lead to floods and damages. Water-permeable pavements have a high infiltration rate that reduces surface runoff by increasing the groundwater recharge. The high water retention capacity of the street body of up to 51 l/m(2) and its connection via pores to the surface lead to higher evaporation rates than impermeable surfaces. A comparison of these two kinds of pavements shows a 16% increase in evaporation levels of water-permeable pavements. Furthermore, the evaporation from impermeable pavements is linked directly to rain events due to fast-drying surfaces. Water-permeable pavements show a more evenly distributed evaporation after a rain event. Cooling effects by evaporative heat loss can improve the city climate even several days after rain events. On a large scale use, uncomfortable weather like sultriness or dry heat can be prevented and the urban water balance can be attenuated towards the natural.

Field data provide estimates of effective permeability, fracture spacing, well drainage area and incremental production in gas shales

KAUST Repository

Eftekhari, Behzad; Marder, M.; Patzek, Tadeusz

2018-01-01

the external unstimulated reservoir. This allows us to estimate for the first time the effective permeability of the unstimulated shale and the spacing of fractures in the stimulated region. From an analysis of wells in the Barnett shale, we find

Microorganism Removal in Permeable Pavement Parking Lots ...

Science.gov (United States)

Three types of permeable pavements (pervious concrete, permeable interlocking concrete pavers, and porous asphalt) were monitored at the Edison Environmental Center in Edison, New Jersey for indicator organisms such as fecal coliform, enterococci, and E. coli. Results showed that porous asphalt had much lower concentration in monitored infiltrate compared to pervious concrete and permeable interlocking concrete pavers. Concentrations of monitored organisms in infiltrate from porous asphalt were consistently below the bathing water quality standard. Fecal coliform and enterococci exceeded bathing water quality standards more than 72% and 34% of the time for permeable interlocking concrete pavers and pervious concrete, respectively. Purpose is to evaluate the performance of permeable pavement in removing indicator organisms from infiltrating stormwater runoff.

The Effect of External Magnetic Field on Dielectric Permeability of Multiphase Ferrofluids

Science.gov (United States)

Dotsenko, O. A.; Pavlova, A. A.; Dotsenko, V. S.

2018-03-01

Nowadays, ferrofluids are applied in various fields of science and technology, namely space, medicine, geology, biology, automobile production, etc. In order to investigate the feasibility of applying ferrofluids in magnetic field sensors, the paper presents research into the influence of the external magnetic field on dielectric permeability of ferrofluids comprising magnetite nanopowder, multiwall carbon nanotubes, propanetriol and deionized water. The real and imaginary parts of the dielectric permeability change respectively by 3.7 and 0.5% when applying the magnetic field parallel to the electric. The findings suggest that the considered ferrofluid can be used as a magnetic level gauge or in design of variable capacitors.

AAnti-leakage mechanism and effect of sodium aescinate on the permeability of blood-brain barrier

Directory of Open Access Journals (Sweden)

Ping GUO

2012-02-01

Full Text Available Objective  To study the anti-leakage mechanism and protective effect of sodium aescinate on the blood-brain barrier of rats acutely exposed to hypoxia. Methods  Seventy-five healthy SD rats were randomly divided into 3 groups (25 each: normoxic control (NC, simple hypoxic (SH and drug treated (DT group. Acute hypoxia brain edema rat model was established by a simulation of acute high-altitude hypoxia for 5 days. The cerebral water content was determined by dry-wet method. The permeability of the blood-brain barrier (BBB was evaluated by Evans blue (EB method. The pathological change of the brain was detected by HE staining. The state of BBB tight junction (TJ and ultrastructures of the brain tissues were observed by lanthanum nitrate tracer method under transmission electron microscope (TEM. Protein and mRNA expression of Occludin, Zo-1 and Claudin-5 were investigated by immunohistochemistry, Western-blotting and real-time PCR respectively. Results  After exposure to acute hypoxia for 5 days, compared with NC group, the water content of brain in SH group increased obviously (PPPPPConclusion  Acute hypoxia exposure may lead to a remarkable decline of the expressions of rat's brain Occludin protein and the Occludin, Zo-1 and Claudin-5 mRNA, and an obvious increase of BBB permeability. Sodium aescinate can up-regulate the expression level of these molecules and decrease BBB permeability, thus playing a profitable role of anti-leakage and BBB protection.

Use of Interface Treatment to Reduce Emissions from Residuals in Lower Permeability Zones to Groundwater flowing Through More Permeable Zones (Invited)

Science.gov (United States)

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.

Fracture network topology and characterization of structural permeability

Science.gov (United States)

Hansberry, Rowan; King, Rosalind; Holford, Simon

2017-04-01

There are two fundamental requirements for successful geothermal development: elevated temperatures at accessible depths, and a reservoir from which fluids can be extracted. The Australian geothermal sector has successfully targeted shallow heat, however, due in part to the inherent complexity of targeting permeability, obtaining adequate flow rates for commercial production has been problematic. Deep sedimentary aquifers are unlikely to be viable geothermal resources due to the effects of diagenetic mineral growth on rock permeability. Therefore, it is likely structural permeability targets, exploiting natural or induced fracture networks will provide the primary means for fluid flow in geothermal, as well as unconventional gas, reservoirs. Recent research has focused on the pattern and generation of crustal stresses across Australia, while less is known about the resultant networks of faults, joints, and veins that can constitute interconnected sub-surface permeability pathways. The ability of a fracture to transmit fluid is controlled by the orientation and magnitude of the in-situ stress field that acts on the fracture walls, rock strength, and pore pressure, as well as fracture properties such as aperture, orientation, and roughness. Understanding the distribution, orientation and character of fractures is key to predicting structural permeability. This project focuses on extensive mapping of fractures over various scales in four key Australian basins (Cooper, Otway, Surat and Perth) with the potential to host geothermal resources. Seismic attribute analysis is used in concert with image logs from petroleum wells, and field mapping to identify fracture networks that are usually not resolved in traditional seismic interpretation. We use fracture network topology to provide scale-invariant characterisation of fracture networks from multiple data sources to assess similarity between data sources, and fracture network connectivity. These results are compared with

INTESTINAL PERMEABILITY IN PATIENTS WITH CELIAC-DISEASE AND RELATIVES OF PATIENTS WITH CELIAC-DISEASE

NARCIS (Netherlands)

van Elburg, R. M.; Uil, J. J.; Mulder, C. J.; Heymans, H. S.

1993-01-01

The functional integrity of the small bowel is impaired in coeliac disease. Intestinal permeability, as measured by the sugar absorption test probably reflects this phenomenon. In the sugar absorption test a solution of lactulose and mannitol was given to the fasting patient and the

INTESTINAL PERMEABILITY IN PATIENTS WITH CELIAC-DISEASE AND RELATIVES OF PATIENTS WITH CELIAC-DISEASE

NARCIS (Netherlands)

VANELBURG, RM; UIL, JJ; MULDER, CJJ; HEYMANS, HSA

The functional integrity of the small bowel is impaired in coeliac disease. Intestinal permeability, as measured by the sugar absorption test probably reflects this phenomenon. In the sugar absorption test a solution of lactulose and mannitol was given to the fasting patient and the

A new coal-permeability model: Internal swelling stress and fracture-matrix interaction

Energy Technology Data Exchange (ETDEWEB)

Liu, H.H.; Rutqvist, J.

2009-10-01

We have developed a new coal-permeability model for uniaxial strain and constant confining stress conditions. The model is unique in that it explicitly considers fracture-matrix interaction during coal deformation processes and is based on a newly proposed internal-swelling stress concept. This concept is used to account for the impact of matrix swelling (or shrinkage) on fracture-aperture changes resulting from partial separation of matrix blocks by fractures that do not completely cut through the whole matrix. The proposed permeability model is evaluated with data from three Valencia Canyon coalbed wells in the San Juan Basin, where increased permeability has been observed during CH{sub 4} gas production, as well as with published data from laboratory tests. Model results are generally in good agreement with observed permeability changes. The importance of fracture-matrix interaction in determining coal permeability, demonstrated in this work using relatively simple stress conditions, underscores the need for a dual-continuum (fracture and matrix) mechanical approach to rigorously capture coal-deformation processes under complex stress conditions, as well as the coupled flow and transport processes in coal seams.

Investigating Multiphase Flow Phenomena in Fine-Grained Reservoir Rocks: Insights from Using Ethane Permeability Measurements over a Range of Pore Pressures

Directory of Open Access Journals (Sweden)

Eric Aidan Letham

2018-01-01

Full Text Available The ability to quantify effective permeability at the various fluid saturations and stress states experienced during production from shale oil and shale gas reservoirs is required for efficient exploitation of the resources, but to date experimental challenges prevent measurement of the effective permeability of these materials over a range of fluid saturations. To work towards overcoming these challenges, we measured effective permeability of a suite of gas shales to gaseous ethane over a range of pore pressures up to the saturated vapour pressure. Liquid/semiliquid ethane saturation increases due to adsorption and capillary condensation with increasing pore pressure resulting in decreasing effective permeability to ethane gas. By how much effective permeability to ethane gas decreases with adsorption and capillary condensation depends on the pore size distribution of each sample and the stress state that effective permeability is measured at. Effective permeability decreases more at higher stress states because the pores are smaller at higher stress states. The largest effective permeability drops occur in samples with dominant pore sizes in the mesopore range. These pores are completely blocked due to capillary condensation at pore pressures near the saturated vapour pressure of ethane. Blockage of these pores cuts off the main fluid flow pathways in the rock, thereby drastically decreasing effective permeability to ethane gas.

Lung epithelial permeability and inhaled furosemide. Added dimensions in asthmatics

International Nuclear Information System (INIS)

Bhure, U.N.; Bhure, S.U.; Bhatt, B.M.; Mistry, S.; Pednekar, S.J.; Chari, V.V.; Desai, S.A.; Joshi, J.M.; Paidhungat, A.J.

2009-01-01

Lung clearance rates of inhaled 99m Tc-diethylene-triamine-pentaacetic acid (DTPA) aerosols constitute a sensitive index to evaluate the permeability changes characteristic of airway epithelial damage. It was thought that edema of the airway wall which is reported in asthma could be relieved with a diuretic like furosemide, helping to relieve the symptoms. We intended to study the effect of inhaled furosemide on lung epithelial permeability in asthmatics and smokers with the help of 99m Tc-DTPA lung clearance test (LCT). The study included three groups (n=15), viz. normal healthy controls, asymptomatic chronic smokers, and chronic persistent asthmatics. Each subject underwent the LCT twice, baseline and post-furosemide (Lasix) study, within a week's interval. The post-furosemide study was carried out 15 min after inhalation of 10 mg of lasix. Lung epithelial permeability was determined in terms of clearance half-life (T 1/2 ). The baseline mean T 1/2 values for controls, smokers, and asthmatics were 50.95±16.58, 20.81±5.47, 24.06±6.19 min, respectively. Post-lasix T 1/2 values were 50.83±15.84, 20.70±5.65, 41.27±15.07 min, respectively. There was a significant difference (P<0.001) in baseline and post-lasix clearance values in asthmatics only. Baseline lung epithelial permeability was altered in smokers and asthmatics compared to the controls. Furosemide was effective only in asthmatics in reverting the permeability almost back to the normal range. Inhaled furosemide was effective even in moderate and severe asthmatics. Furosemide has multiple mechanisms of action. It possibly acts at bronchial level in view of the pathology in asthmatics lying in the airways. (author)

Permeability of commercial solvents through living human skin

DEFF Research Database (Denmark)

Ursin, C; Hansen, C M; Van Dyk, J W

1995-01-01

A procedure has been developed for measuring the steady state rate of permeation of commercial solvents through living human skin. To get the most consistent results, it was necessary with some solvents to normalize the solvent permeation rate of a given skin sample with its [3H]water permeation...... rate. For other solvents this was not necessary, so the un-normalized data were used. High [3H]water permeation rate also was used as a criterion for "defective" skin samples that gave erroneous permeability rates, especially for solvents having slow permeability. The linearity of the steady state data...... of DMSO and octyl acetate were measured. No octyl acetate was detected and the permeability of DMSO was proportional to its mole fraction in the mixture. The effect of two hours of solvent exposure on the viability of skin (based on DNA synthesis) was measured and found to be very dependent on the solvent....

The novel oral imatinib microemulsions: physical properties, cytotoxicity activities and improved Caco-2 cell permeability.

Science.gov (United States)

Gundogdu, Evren; Karasulu, Hatice Yesim; Koksal, Cinel; Karasulu, Ercüment

2013-01-01

The objective of this study was to formulate imatinib (IM) loaded to water-in-oil (w/o) microemulsions as an alternative formulation for cancer therapy and to evaluate the cytotoxic effect of microemulsions Caco-2 and MCF-7. Moreover, permeability studies were also performed with Caco-2 cells. W/o microemulsion systems were developed by using pseudo-ternary phase diagram. According to cytotoxicity studies, all formulations did not exert a cytotoxic effect on Caco-2 cells. Furthermore, all formulations had a significant cytotoxic effect on MCF-7 cells and the cytotoxic effect of M3IM was significantly more than that of other microemulsions and IM solution (p < 0.05). The permeability studies of IM across Caco-2 cells showed that permeability value from apical to basolateral was higher than permeability value of other formulations. In conclusion, the microemulsion formulations as a drug carrier, especially M3IM formulation, may be used as an effective alternative breast cancer therapy for oral delivery of IM.

Frictional stability-permeability relationships for fractures in shales

Science.gov (United States)

Fang, Yi; Elsworth, Derek; Wang, Chaoyi; Ishibashi, Takuya; Fitts, Jeffrey P.

2017-03-01

There is wide concern that fluid injection in the subsurface, such as for the stimulation of shale reservoirs or for geological CO2 sequestration (GCS), has the potential to induce seismicity that may change reservoir permeability due to fault slip. However, the impact of induced seismicity on fracture permeability evolution remains unclear due to the spectrum of modes of fault reactivation (e.g., stable versus unstable). As seismicity is controlled by the frictional response of fractures, we explore friction-stability-permeability relationships through the concurrent measurement of frictional and hydraulic properties of artificial fractures in Green River shale (GRS) and Opalinus shale (OPS). We observe that carbonate-rich GRS shows higher frictional strength but weak neutral frictional stability. The GRS fracture permeability declines during shearing while an increased sliding velocity reduces the rate of permeability decline. By comparison, the phyllosilicate-rich OPS has lower friction and strong stability while the fracture permeability is reduced due to the swelling behavior that dominates over the shearing induced permeability reduction. Hence, we conclude that the friction-stability-permeability relationship of a fracture is largely controlled by mineral composition and that shale mineral compositions with strong frictional stability may be particularly subject to permanent permeability reduction during fluid infiltration.

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

Science.gov (United States)

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

2015-01-01

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 R2=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 (Q2ext = 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. PMID:25560673

Regulation of endothelial cell shape and monolayer permeability by atrial natriuretic peptide

International Nuclear Information System (INIS)

Lofton-Day, C.E.

1989-01-01

Atrial natriuretic peptide (ANP), considered to be an important regulator of intravascular fluid volume, binds specifically to receptors on endothelial cells. In this study, the role of ANP-specific binding was investigated by examining the effect of ANP on the morphology and macromolecular permeability of monolayer cultures of bovine aortic endothelial cells. ANP alone had no observable effect on the monolayers. However, incubation of monolayers with ANP antagonized thrombin- or glucose oxidase-induced cell shape changes and intercellular gap formation. ANP pretreatment also opposed the effect of thrombin and glucose oxidase on actin filament distribution as observed by rhodamine-phalloidin staining and digital image analysis of F0actin staining. In addition, ANP reversed cell shape changes and cytoskeletal alterations induced by thrombin treatment but did not reverse alternations induced by glucose oxidase treatment. ANP significantly reduced increases in monolayer permeability to albumin resulting from thrombin or glucose oxidases treatment. Thrombin caused a 2-fold increase in monolayer permeability to 125 I-labeled albumin, which was abolished by 10 -8 -10 -6 M ANP pretreatment. Glucose oxidase caused similar increases in permeability and was inhibited by ANP at slightly shorter time periods

Effects of roof tile permeability on the thermal performance of ventilated roofs. Analysis of annual performance

Energy Technology Data Exchange (ETDEWEB)

D' Orazio, M.; Di Perna, C.; Principi, P.; Stazi, A. [DACS, Universita politecnica delle Marche, 60100 Ancona (Italy)

2008-07-01

This paper shows the results of the second part of an experimental study aimed at analysing the effects of roof tile permeability on the thermal performances of ventilation ducts. Ventilation ducts under the layer of tiles are typically used in south European countries to limit the energy load during the summer period. The results of the first part of the study, carried out by analysing 14 different types of roof, proved that the air permeability of the layer of tiles determines a certain amount of heat to be released, in addition to the release connected with the stack effect, in ventilation ducts which have the same characteristics but are perfectly airtight. However, the study did not completely resolve some issues since it was carried out on a model roof (6 m x 1.5 m) with devices to raise the layer of tiles and to create the ventilation duct but without those building elements which are present in real roofs and are used to stop insects and small animals from entering the ventilation duct. These elements narrow the inlet and outlet and consequently cause important reductions in pressure. Moreover, the measurements were based on data collected for limited periods of time during the summer season. So as to eliminate any possible uncertainty from the results of the research, the study continued with the creation of a model building on which five types of ventilated roof with different cross sections of the ventilation duct were analysed. The results show that the presence of air permeable layers and elements to protect the ventilation duct eliminate any differences in performance which were due to the cross section of the ventilation duct. (author)

Effect of iron content on permeability and power loss characteristics ...

Indian Academy of Sciences (India)

Administrator

have been measured by vibrating sample magnetometer (VSM). The permeability of cadmium doped lithium ferrites exhibited higher values than zinc doped lithium ferrites. The power loss of cadmium doped lithium ferrites is lesser as compared to zinc doped lithium ferrites in the frequency range of 50–5000 kHz and at flux.

Studies on the increase of capillary permeability in rat skin under the action of pyridoxal 5' phosphate

International Nuclear Information System (INIS)

Garcia Agudo, N.L. del M. de.

1979-01-01

The activity of pyridoxal 5'-phosphate (PLP) is described on the vascular permeability response, measured in the abdominal wall of rats from the amount of extravased Evans blue labelled with radioactive iodine 125 or 131. The PLP effect is related to histamine release as it has been showed by tha use of antihistaminics. An attempt has been made in order to correlate structure and biological activity by using PLP analogs. The intact molecule of PLP seems to be the proper active substance. The critical role of calcium in histamine release is discussed in relation to our observations. In the presence of high concentrations of calcium and lantanium, PLP fails to increase the vascular permeability; magnesium does not show any influence. The calcium mobilization produced by theophylline results in inhibition of the response. The course of the reaction between PLP and histamine in vitro was followed; the synthetic cyclic product is deprived of activity and does not interfere with the intrinsic effects of PLP and histamine. (Author) [pt

Integrated petrophysical and reservoir characterization workflow to enhance permeability and water saturation prediction

Science.gov (United States)

Al-Amri, Meshal; Mahmoud, Mohamed; Elkatatny, Salaheldin; Al-Yousef, Hasan; Al-Ghamdi, Tariq

2017-07-01

Accurate estimation of permeability is essential in reservoir characterization and in determining fluid flow in porous media which greatly assists optimize the production of a field. Some of the permeability prediction techniques such as Porosity-Permeability transforms and recently artificial intelligence and neural networks are encouraging but still show moderate to good match to core data. This could be due to limitation to homogenous media while the knowledge about geology and heterogeneity is indirectly related or absent. The use of geological information from core description as in Lithofacies which includes digenetic information show a link to permeability when categorized into rock types exposed to similar depositional environment. The objective of this paper is to develop a robust combined workflow integrating geology and petrophysics and wireline logs in an extremely heterogeneous carbonate reservoir to accurately predict permeability. Permeability prediction is carried out using pattern recognition algorithm called multi-resolution graph-based clustering (MRGC). We will bench mark the prediction results with hard data from core and well test analysis. As a result, we showed how much better improvements are achieved in the permeability prediction when geology is integrated within the analysis. Finally, we use the predicted permeability as an input parameter in J-function and correct for uncertainties in saturation calculation produced by wireline logs using the classical Archie equation. Eventually, high level of confidence in hydrocarbon volumes estimation is reached when robust permeability and saturation height functions are estimated in presence of important geological details that are petrophysically meaningful.

Third invitational well-testing symposium: well testing in low permeability environments

Energy Technology Data Exchange (ETDEWEB)

Doe, T.W.; Schwarz, W.J. (eds.)

1981-03-01

The testing of low permeability rocks is common to waste disposal, fossil energy resource development, underground excavation, and geothermal energy development. This document includes twenty-six papers and abstracts, divided into the following sessions: opening session, case histories and related phenomena, well test design in low permeability formations, analysis and interpretation of well test data, and instrumentation for well tests. Separate abstracts were prepared for 15 of the 16 papers; the remaining paper has been previously abstracted. (DLC)

Third invitational well-testing symposium: well testing in low permeability environments

International Nuclear Information System (INIS)

Doe, T.W.; Schwarz, W.J.

1981-03-01

The testing of low permeability rocks is common to waste disposal, fossil energy resource development, underground excavation, and geothermal energy development. This document includes twenty-six papers and abstracts, divided into the following sessions: opening session, case histories and related phenomena, well test design in low permeability formations, analysis and interpretation of well test data, and instrumentation for well tests. Separate abstracts were prepared for 15 of the 16 papers; the remaining paper has been previously abstracted

Development and characterization of a new oral dapsone nanoemulsion system: permeability and in silico bioavailability studies

Directory of Open Access Journals (Sweden)

Monteiro LM

2012-09-01

Full Text Available Lidiane M Monteiro,1 Viviane F Lione,1 Flavia A do Carmo,1 Lilian H do Amaral,1 Julianna H da Silva,2 Luiz E Nasciutti,2 Carlos R Rodrigues,1 Helena C Castro,3 Valeria P de Sousa,1 Lucio M Cabral11Faculdade de Farmácia, Universidade Federal do Rio de Janeiro, 2Instituto de Ciências Biomédicas, Universidade Federal do Rio de Janeiro, 3Instituto de Biologia, Universidade Federal Fluminense, Niterói, Rio de Janeiro, BrasilBackground: Dapsone is described as being active against Mycobacterium leprae, hence its role in the treatment of leprosy and related pathologies. Despite its therapeutic potential, the low solubility of dapsone in water results in low bioavailability and high microbial resistance. Nanoemulsions are pharmaceutical delivery systems derived from micellar solutions with a good capacity for improving absorption. The aim of this work was to develop and compare the permeability of a series of dapsone nanoemulsions in Caco-2 cell culture against that of effective permeability in the human body simulated using GastroplusTM software.Methods and results: The release profiles of the dapsone nanoemulsions using different combinations of surfactants and cosolvent showed a higher dissolution rate in simulated gastric and enteric fluid than did the dispersed dapsone powder. The drug release kinetics were consistent with a Higuchi model.Conclusion: This comparison of dapsone permeability in Caco-2 cells with effective permeability in the human body simulated by Gastroplus showed a good correlation and indicates potential improvement in the biodisponibility of dapsone using this new system.Keywords: dapsone, nanoemulsions, antibacterial, permeability, Caco-2 cell, GastroplusTM

Effect of heterogeneity on the characterization of cell membrane compartments: I. Uniform size and permeability.

Science.gov (United States)

Hall, Damien

2010-03-15

Observations of the motion of individual molecules in the membrane of a number of different cell types have led to the suggestion that the outer membrane of many eukaryotic cells may be effectively partitioned into microdomains. A major cause of this suggested partitioning is believed to be due to the direct/indirect association of the cytosolic face of the cell membrane with the cortical cytoskeleton. Such intimate association is thought to introduce effective hydrodynamic barriers into the membrane that are capable of frustrating molecular Brownian motion over distance scales greater than the average size of the compartment. To date, the standard analytical method for deducing compartment characteristics has relied on observing the random walk behavior of a labeled lipid or protein at various temporal frequencies and different total lengths of time. Simple theoretical arguments suggest that the presence of restrictive barriers imparts a characteristic turnover to a plot of mean squared displacement versus sampling period that can be interpreted to yield the average dimensions of the compartment expressed as the respective side lengths of a rectangle. In the following series of articles, we used computer simulation methods to investigate how well the conventional analytical strategy coped with heterogeneity in size, shape, and barrier permeability of the cell membrane compartments. We also explored questions relating to the necessary extent of sampling required (with regard to both the recorded time of a single trajectory and the number of trajectories included in the measurement bin) for faithful representation of the actual distribution of compartment sizes found using the SPT technique. In the current investigation, we turned our attention to the analytical characterization of diffusion through cell membrane compartments having both a uniform size and permeability. For this ideal case, we found that (i) an optimum sampling time interval existed for the analysis

Ascorbic acid attenuates endothelial permeability triggered by cell-free hemoglobin.

Science.gov (United States)

Kuck, Jamie L; Bastarache, Julie A; Shaver, Ciara M; Fessel, Joshua P; Dikalov, Sergey I; May, James M; Ware, Lorraine B

2018-01-01

Increased endothelial permeability is central to shock and organ dysfunction in sepsis but therapeutics targeted to known mediators of increased endothelial permeability have been unsuccessful in patient studies. We previously reported that cell-free hemoglobin (CFH) is elevated in the majority of patients with sepsis and is associated with organ dysfunction, poor clinical outcomes and elevated markers of oxidant injury. Others have shown that Vitamin C (ascorbate) may have endothelial protective effects in sepsis. In this study, we tested the hypothesis that high levels of CFH, as seen in the circulation of patients with sepsis, disrupt endothelial barrier integrity. Human umbilical vein endothelial cells (HUVEC) were grown to confluence and treated with CFH with or without ascorbate. Monolayer permeability was measured by Electric Cell-substrate Impedance Sensing (ECIS) or transfer of 14 C-inulin. Viability was measured by trypan blue exclusion. Intracellular ascorbate was measured by HPLC. CFH increased permeability in a dose- and time-dependent manner with 1 mg/ml of CFH increasing inulin transfer by 50% without affecting cell viability. CFH (1 mg/ml) also caused a dramatic reduction in intracellular ascorbate in the same time frame (1.4 mM without CFH, 0.23 mM 18 h after 1 mg/ml CFH, p < 0.05). Pre-treatment of HUVECs with ascorbate attenuated CFH induced permeability. CFH increases endothelial permeability in part through depletion of intracellular ascorbate. Supplementation of ascorbate can attenuate increases in permeability mediated by CFH suggesting a possible therapeutic approach in sepsis. Copyright © 2017 Elsevier Inc. All rights reserved.

Permeability enhancement by shock cooling

Science.gov (United States)

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

Lifelong consumption of sodium selenite: gender differences on blood-brain barrier permeability in convulsive, hypoglycemic rats.

Science.gov (United States)

Seker, F Burcu; Akgul, Sibel; Oztas, Baria

2008-07-01

The aim of this study was to compare the effects of hypoglycemia and induced convulsions on the blood-brain barrier permeability in rats with or without lifelong administration of sodium selenite. There is a significant decrease of the blood-brain barrier permeability in three brain regions of convulsive, hypoglycemic male rats treated with sodium selenite when compared to sex-matched untreated rats (p0.05). The blood-brain barrier permeability of the left and right hemispheres of untreated, moderately hypoglycemic convulsive rats of both genders was better than their untreated counterparts (peffect against blood-brain barrier permeability during convulsions and that the effects of sodium selenite are gender-dependent.

Research on the performance of sand-based environmental-friendly water permeable bricks

Science.gov (United States)

Cai, Runze; Mandula; Chai, Jinyi

2018-02-01

This paper examines the effects of the amount of admixture, the water cement ratio, the aggregate grading, and the cement aggregate ratio on the mechanical service properties and of porous concrete pavement bricks including strength, water permeability, frost resistance, and wear resistance. The admixture can enhance the performance of water permeable brick, and optimize the design mix. Experiments are conducted to determine the optimal mixing ratios which are given as; (1) the admixture (self-developed) within the content of 5% of the cement quality; (2) water-cement ratio equal to 0.34; (3) cement-aggregate ratio equal to 0.25; (4) fine aggregate of 70% (particle size 0.6-2.36mm); and coarse aggregate of 30% (particle size: 2.36-4.75mm). The experimental results that the sand-based permeable concrete pavement brick has a strength of 35.6MPa and that the water permeability coefficient is equal to 3.5×10-2cm/s. In addition, it was found that the concrete water permeable brick has good frost resistance and surface wear resistance, and that the its production costs are much lower than the similar sand-based water permeable bricks in China.

Report on Hydrologic Flow in Low-Permeability Media

Energy Technology Data Exchange (ETDEWEB)

Liu, Hui-Hai; Birkholzer, Jens

2013-11-13

We demonstrate that under normal conditions (under which there are no intersections between tunnels/drifts and conductive geological structures, such as faults), the water flow velocity in the damage zone, as a result of non-Darcian flow behavior, is extremely small such that solute transport is dominated by diffusion, rather than advection. We show that unless non-Darcian flow behavior is considered, significant errors can occur in the “measured” relative-permeability values. We propose a hypothesis to consider the temperature impact based on limited test results from the petroleum literature. To consider the bedding effects, we present an empirical relationship between water flux and hydraulic gradient for non-Darcian water flow in anisotropic cases.

Modeling of damage, permeability changes and pressure responses during excavation of the TSX tunnel in granitic rock at URL, Canada

Science.gov (United States)

Rutqvist, Jonny; Börgesson, Lennart; Chijimatsu, Masakazu; Hernelind, Jan; Jing, Lanru; Kobayashi, Akira; Nguyen, Son

2009-05-01

This paper presents numerical modeling of excavation-induced damage, permeability changes, and fluid-pressure responses during excavation of a test tunnel associated with the tunnel sealing experiment (TSX) at the Underground Research Laboratory (URL) in Canada. Four different numerical models were applied using a wide range of approaches to model damage and permeability changes in the excavation disturbed zone (EDZ) around the tunnel. Using in situ calibration of model parameters, the modeling could reproduce observed spatial distribution of damage and permeability changes around the tunnel as a combination of disturbance induced by stress redistribution around the tunnel and by the drill-and-blast operation. The modeling showed that stress-induced permeability increase above the tunnel is a result of micro and macrofracturing under high deviatoric (shear) stress, whereas permeability increase alongside the tunnel is a result of opening of existing microfractures under decreased mean stress. The remaining observed fracturing and permeability changes around the periphery of the tunnel were attributed to damage from the drill-and-blast operation. Moreover, a reasonably good agreement was achieved between simulated and observed excavation-induced pressure responses around the TSX tunnel for 1 year following its excavation. The simulations showed that these pressure responses are caused by poroelastic effects as a result of increasing or decreasing mean stress, with corresponding contraction or expansion of the pore volume. The simulation results for pressure evolution were consistent with previous studies, indicating that the observed pressure responses could be captured in a Biot model using a relatively low Biot-Willis’ coefficient, α ≈ 0.2, a porosity of n ≈ 0.007, and a relatively low permeability of k ≈ 2 × 10-22 m2, which is consistent with the very tight, unfractured granite at the site.

Study of pressure drop, void fraction and relative permeabilities of two phase flow through porous media

International Nuclear Information System (INIS)

Chu, W.; Dhir, V.K.; Marshall, J.

1983-01-01

An experimental investigation of two phase flow through porous layers formed of non-heated glass particles (nominal diameter 1 to 6 mm) has been made. Particulate bed depths of 30 cm and 70 cm were used. The effect of particle size, particle size distribution and bed porosity on void fraction and pressure drop through a particulate bed formed in a cylindrical test section has been investigated. The superficial velocity of liquid (water) is varied from 1.83 to 18.3 mm/s while the superficial velocity of gas (air) is varied from 0 to 68.4 mm/s. These superficial velocities were chosen so that pressure drop and void fraction measurement could be made for the porous layer in fixed and fluidized states. A model based on drift flux approach has been developed for the void fraction. Using the two phase friction pressure drop data, the relative permeabilities of the two phases have been concluded with void fraction. The void fraction and two phase friction pressure gradient in beds composed of mixtures of spherical particles as well as sharps of different nominal sizes have also been examined. It is found that the models for single size particles are also applicable to mixtures of particles if a mean particle diameter for the mixture is defined

Surface-subsurface turbulent interaction at the interface of a permeable bed: influence of the wall permeability

Science.gov (United States)

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

2017-12-01

Coarse-gravel river beds possess a high degree of permeability. Flow interactions between surface and subsurface flow across the bed interface is key to a number of natural processes occurring in the hyporheic zone. In fact, it is increasingly recognized that these interactions drive mass, momentum and energy transport across the interface, and consequently control biochemical processes as well as stability of sediments. The current study explores the role of the wall permeability in surface and subsurface flow interaction under controlled experimental conditions on a physical model of a gravel bed. The present wall model was constructed by five layers of cubically arranged spheres (d=25.4mm, where d is a diameter) providing 48% of porosity. Surface topography was removed by cutting half of a diameter on the top layer of spheres to render the flow surface smooth and highlight the impact of the permeability on the overlying flow. An impermeable smooth wall was also considered as a baseline of comparison for the permeable wall flow. To obtain basic flow statistics, low-frame-rate high-resolution PIV measurements were performed first in the streamwise-wall-normal (x-y) plane and refractive-index matching was employed to optically access the flow within the permeable wall. Time-resolved PIV experiments in the same facility were followed to investigate the flow interaction across the wall interface in sptaio-temporal domain. In this paper, a detailed analysis of the first and second order velocity statistics as well as the amplitude modulation for the flow overlying the permeable smooth wall will be presented.

Apolipoprotein L1 confers pH-switchable ion permeability to phospholipid vesicles.

Science.gov (United States)

Bruno, Jonathan; Pozzi, Nicola; Oliva, Jonathan; Edwards, John C

2017-11-03

Apolipoprotein L1 (ApoL1) is a human serum protein conferring resistance to African trypanosomes, and certain ApoL1 variants increase susceptibility to some progressive kidney diseases. ApoL1 has been hypothesized to function like a pore-forming colicin and has been reported to have permeability effects on both intracellular and plasma membranes. Here, to gain insight into how ApoL1 may function in vivo , we used vesicle-based ion permeability, direct membrane association, and intrinsic fluorescence to study the activities of purified recombinant ApoL1. We found that ApoL1 confers chloride-selective permeability to preformed phospholipid vesicles and that this selectivity is strongly pH-sensitive, with maximal activity at pH 5 and little activity above pH 7. When ApoL1 and lipid were allowed to interact at low pH and were then brought to neutral pH, chloride permeability was suppressed, and potassium permeability was activated. Both chloride and potassium permeability linearly correlated with the mass of ApoL1 in the reaction mixture, and both exhibited lipid selectivity, requiring the presence of negatively charged lipids for activity. Potassium, but not chloride, permease activity required the presence of calcium ions in both the association and activation steps. Direct assessment of ApoL1-lipid associations confirmed that ApoL1 stably associates with phospholipid vesicles, requiring low pH and the presence of negatively charged phospholipids for maximal binding. Intrinsic fluorescence of ApoL1 supported the presence of a significant structural transition when ApoL1 is mixed with lipids at low pH. This pH-switchable ion-selective permeability may explain the different effects of ApoL1 reported in intracellular and plasma membrane environments. © 2017 by The American Society for Biochemistry and Molecular Biology, Inc.

A model experiment of liquefaction and fluid transport: quantifying the effect of permeability discontinuity

Science.gov (United States)

Yasuda, N.; Sumita, I.

2013-12-01

and accumulates at the interface, after which it migrates upwards, 3: water discharge ends, and particles settle. We measured the relaxation time needed for the discharge and compaction to end. Because low-permeability layer inhibits pore water from rising, longer time is needed for a two-layer case compared to the one-layer case. When the particle size of the upper layer is about 1/3 or smaller than that of the lower layer, relaxation time becomes independent of the bottom particle size. We modeled the relaxation time by introducing the effective permeability of two-layered medium, and find that it explains the measurements well. References Nohguchi, Y., 2004, ICTAM04 Proceedings, Warsaw, Poland. Peacock, D. C. P., 2006, J. Geosci.Ed, 54, 550

Factors Determining the Oxygen Permeability of Biological Membranes: Oxygen Transport Across Eye Lens Fiber-Cell Plasma Membranes.

Science.gov (United States)

Subczynski, Witold Karol; Widomska, Justyna; Mainali, Laxman

2017-01-01

Electron paramagnetic resonance (EPR) spin-label oximetry allows the oxygen permeability coefficient to be evaluated across homogeneous lipid bilayer membranes and, in some cases, across coexisting membrane domains without their physical separation. The most pronounced effect on oxygen permeability is observed for cholesterol, which additionally induces the formation of membrane domains. In intact biological membranes, integral proteins induce the formation of boundary and trapped lipid domains with a low oxygen permeability. The effective oxygen permeability coefficient across the intact biological membrane is affected not only by the oxygen permeability coefficients evaluated for each lipid domain but also by the surface area occupied by these domains in the membrane. All these factors observed in fiber cell plasma membranes of clear human eye lenses are reviewed here.

Principal permeability determination from multiple horizontal well tests

Energy Technology Data Exchange (ETDEWEB)

Economides, M. [Texas A and M Univ., TX (United States); Munoz, A.; Ehlig-Economides, C.

1998-12-31

A method for obtaining principal permeability magnitudes and direction that requires only the linear flow regime from transient tests in three horizontal wells oriented in three distinct and arbitrary directions, is described. Well design optimization strategies require knowledge of both the principal permeability orientation as well as the horizontal permeability magnitudes. When the degree of horizontal permeability anisotropy (i.e. permeability in the bedding plane with respect to direction) is significant, the productivity of a long horizontal well will depend greatly on its direction, especially when the well is first brought into production. Productivities have been found to deviate substantially among wells in the same reservoir and this deviation has been attributed to differences in well orientation. In view of this fact, measuring permeability anisotropy becomes a compelling necessity. The success of the proposed method is illustrated by a case study in which the principal permeability magnitudes and direction from three wells were used to predict the productivity of a fourth well within 10 per cent. Use of the computed principal permeabilities from the case study, it was possible to forecast the cumulative production to show the significance of well trajectory optimization on the discounted cash flow and the net present value. 20 refs., 3 figs.

Changes in permeability of the alveolar-capillary barrier in firefighters.

Science.gov (United States)

Minty, B D; Royston, D; Jones, J G; Smith, D J; Searing, C S; Beeley, M

1985-09-01

The effect on alveolar-capillary barrier permeability of chronic exposure to a smoke produced by the partial combusion of diesel oil, paraffin, and wood was examined. An index of permeability was determined from the rate of transfer from the lung into the blood of the hydrophilic, labelled chelate 99mTc diethylene triamine penta-acetate (MW 492 dalton). The results of this test were expressed as the half time clearance of the tracer from the lung into the blood (T1/2 LB). The study was carried out at the Royal Naval Firefighting School, HMS Excellent. Permeability index was measured on seven non-smoking naval firefighting instructors who had worked at the school for periods of longer than two and a half months. Tests of airway function and carbon monoxide transfer factor were performed on four of these seven instructors. The results of the permeability index showed a T1/2 LB of 26 min +/- 5 (SEM) which differed significantly from that of normal non-smokers. By contrast all other lung function tests had values within the predicted normal range.

Influence of 2,3-diphosphoglycerate metabolism on sodium-potassium permeability in human red blood cells: studies with bisulfite and other redox agents

Science.gov (United States)

Parker, John C.

1969-01-01

It is known that bisulfite ions can selectively deplete red blood cells of 2,3-diphosphoglycerate (2,3-DPG). Studies of the effects of bisulfite on sodium-potassium permeability and metabolism were undertaken to clarify the physiologic role of the abundant quantities of 2,3-DPG in human erythrocytes. Treatment of cells with bisulfite results in a reversible increase in the passive permeability to Na and K ions. Metabolism of glucose to lactate is increased, with a rise in the intracellular ratio of fructose diphosphate to hexose monophosphate. Cell 2,3-DPG is quantitatively converted to pyruvate and inorganic phosphate. The permeability effects of bisulfite are countered by ethacrynic acid and by such oxidizing agents as pyruvate and methylene blue. Taken together, the results suggest that the effects on Na-K flux of bisulfite are related more to the reducing potential of this anion than to its capacity to deplete cells of 2,3-DPG. PMID:5765015

Permeability Tests on Eastern Scheldt Sand

DEFF Research Database (Denmark)

Jakobsen, Kim Parsberg

on the characteristics of the soil matrix, the permeability is determined for different void ratios. All tests are performed on reconstituted specimens of Eastern Scheldt Sand. The permeability is determined by use of a falling head apparatus. Finally the test results are briefly summarised and a relationship between......The flow through porous media plays an important role in various engineering disciplines, as for example in ground water hydrology and soil mechanics. In the present study the permeability is determined for a fine, saturated sand. As the flow through a porous media strongly depends...

Biopolymer system for permeability modification in porous media

Energy Technology Data Exchange (ETDEWEB)

Stepp, A.K.; Bryant, R.S.; Llave, F.M. [BMD-Oklahoma, Inc., Bartlesville, OK (United States)] [and others

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.

Damage-induced permeability changes around underground excavations

International Nuclear Information System (INIS)

Coll, C.

2005-07-01

The storage of nuclear waste in deep geological formations is now considered more and more as a potential solution. During excavation, a disturbed zone develops in which damaging can be important and which can lead eventually to the failure of the rock. Fluid flow and permeability in the rock mass can be significantly modified producing a possible security risk. Our work consisted in an experimental study of the hydro-mechanical coupling of two argillaceous rocks: Boom clay (Mol, Belgium) and Opalinus clay (Mont-Terri, Switzerland). Triaxial tests were performed in a saturated state to study the permeability evolution of both clays with isotropic and deviatoric stresses. Argillaceous rocks are geo-materials with complex behaviour governed by numerous coupled processes. Strong physico-chemical interactions between the fluid and the solid particles and their very low permeability required the modification of the experimental set up. Moreover, specific procedures were developed to measure permeability and to detect strain localisation in shear bands. We show that for Boom Clay, permeability is not significantly influenced by strain localisation. For Opalinus clay, fracturing can induce an increase of the permeability at low confining pressure. (author)

Effect of iron content on permeability and power loss characteristics of

Indian Academy of Sciences (India)

Magnetic properties like saturation magnetization, coercivity, retentivity have been measured by vibrating sample magnetometer (VSM). The permeability of cadmium doped lithium ferrites exhibited higher values than zinc doped lithium ferrites. The power loss of cadmium doped lithium ferrites is lesser as compared to zinc ...

Long-term Metal Performance of Three Permeable Pavements