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

Improvement of air permeability of Bubbfil nanofiber membrane

Directory of Open Access Journals (Sweden)

Wang Fei-Yan

2018-01-01

Full Text Available Nanofiber membranes always have extremely high filter efficiency and remarkably low pressure drop. In order to further improve air permeability of bubbfil nanofiber membranes, the plasma technology is used for surface treatment in this paper. The results show that plasma treatment can improve air permeability by 4.45%. Under higher power plasma treatment, earthworm like etchings are produced on the membrane surface with fractal dimensions of about 1.138.

Water permeability of acinar cell membranes in the isolated perfused rabbit mandibular salivary gland.

Science.gov (United States)

Steward, M C; Seo, Y; Rawlings, J M; Case, R M

1990-01-01

1. The diffusive water permeability of epithelial cell membranes in the perfused rabbit mandibular salivary gland was measured at 37 degrees C by a 1H nuclear magnetic resonance relaxation method using an extracellular relaxation reagent, gadolinium diethylenetriaminepentaacetic acid (Gd(DTPA)). 2. In glands perfused with a HEPES-buffered solution containing 10 mmol l-1 Gd(DTPA), the spin-lattice (T1) relaxation of the water protons showed two exponential components. The water compartment responsible for the slower component corresponded in magnitude to 71 +/- 5% of the wet weight of the gland, and was attributed to the exchangeable intracellular water of the acinar cells. 3. The rate constant for water efflux from the cells was estimated to be 4.1 +/- 0.1 s-1 which would be consistent with a diffusive membrane permeability (Pd) of approximately 3 x 10(-3) cm s-1. Stimulation with acetylcholine (10(-6) mol l-1) did not cause any detectable change in membrane water permeability. 4. Since the basolateral membrane probably provides the main pathway for water efflux, the osmotic water permeability of this barrier (expressed per gland) was estimated to be less than 6.2 cm3 s-1. This would be insufficient to account for the generation of a near-isosmotic fluid at the flow rates observed during secretion, and suggests that a substantial fraction of the flow of water occurs via a paracellular route. PMID:1966053

Groundwater protection from cadmium contamination by permeable reactive barriers

Energy Technology Data Exchange (ETDEWEB)

Di Natale, F. [Dipartimento di Ingegneria chimica, Universita di Federico II, P.le Tecchio, 80-80125 Naples (Italy)], E-mail: fdinatal@unina.it; Di Natale, M.; Greco, R. [Centro Interdipartimentale di Ricerca in Ingegneria Ambientale (CIRIAM), Dipartimento di Ingegneria Civile, Seconda Universita di Napoli, via Roma 29-81031 Aversa (Caserta) (Italy); Lancia, A. [Dipartimento di Ingegneria chimica, Universita di Federico II, P.le Tecchio, 80-80125 Naples (Italy); Laudante, C.; Musmarra, D. [Centro Interdipartimentale di Ricerca in Ingegneria Ambientale (CIRIAM), Dipartimento di Ingegneria Civile, Seconda Universita di Napoli, via Roma 29-81031 Aversa (Caserta) (Italy)

2008-12-30

This work studies the reliability of an activated carbon permeable reactive barrier in removing cadmium from a contaminated shallow aquifer. Laboratory tests have been performed to characterize the equilibrium and kinetic adsorption properties of the activated carbon in cadmium-containing aqueous solutions. A 2D numerical model has been used to describe pollutant transport within a groundwater and the pollutant adsorption on the permeable adsorbing barrier (PRB). In particular, it has been considered the case of a permeable adsorbing barrier (PAB) used to protect a river from a Cd(II) contaminated groundwater. Numerical results show that the PAB can achieve a long-term efficiency by preventing river pollution for several months.

Permeability of uncharged organic molecules in reverse osmosis desalination membranes.

Science.gov (United States)

Dražević, Emil; Košutić, Krešimir; Svalina, Marin; Catalano, Jacopo

2017-06-01

Reverse osmosis (RO) membranes are primarily designed for removal of salts i.e. for desalination of brackish and seawater, but they have also found applications in removal of organic molecules. While it is clear that steric exclusion is the dominant removal mechanism, the fundamental explanation for how and why the separation occurs remains elusive. Until recently there was no strong microscopic evidences elucidating the structure of the active polyamide layers of RO membranes, and thus they have been conceived as "black boxes"; or as an array of straight capillaries with a distribution of radii; or as polymers with a small amount of polymer free domains. The knowledge of diffusion and sorption coefficients is a prerequisite for understanding the intrinsic permeability of any organic solute in any polymer. At the same time, it is technically challenging to accurately measure these two fundamental parameters in very thin (20-300 nm) water-swollen active layers. In this work we have measured partition and diffusion coefficients and RO permeabilities of ten organic solutes in water-swollen active layers of two types of RO membranes, low (SWC4+) and high flux (XLE). We deduced from our results and recent microscopic studies that the solute flux of organic molecules in polyamide layer of RO membranes occurs in two domains, dense polymer (the key barrier layer) and the water filled domains. Copyright © 2017 Elsevier Ltd. All rights reserved.

Hydraulic performance of permeable barriers for in situ treatment of contaminated groundwater

International Nuclear Information System (INIS)

Smyth, D.J.A.; Shikaze, S.G.; Cherry, J.A.

1997-01-01

The passive interception and in situ treatment of dissolved contaminants in groundwater by permeable reactive barriers has recently gained favor at an increasing number of sites as an alternative to conventional approaches to groundwater remediation such as the pump-and-treat method. Permeable reactive barriers have two essential functions. The first is that the barriers must be installed in a position such that all of the plume passes through the reactive system. The second function is to achieve acceptable treatment of the contamination by physical, chemical or biological means within or downgradient of the barrier. In this paper, issues associated with the hydraulic performance of permeable reaction barriers are evaluated using a three-dimensional groundwater flow model. The efficiency of plume capture by permeable wall and funnel-and-gate systems is examined for some generic and for site-specific hydrogeologic systems. The results have important implications to decisions pertaining to the selection, design and installation of permeable reactive barrier systems

Heavy Cigarette Smokers in a Chinese Population Display a Compromised Permeability Barrier

Science.gov (United States)

Xin, Shujun; Ye, Li; Lv, Chengzhi; Elias, Peter M.

2016-01-01

Cigarette smoking is associated with various cutaneous disorders with defective permeability. Yet, whether cigarette smoking influences epidermal permeability barrier function is largely unknown. Here, we measured skin biophysical properties, including permeability barrier homeostasis, stratum corneum (SC) integrity, SC hydration, skin surface pH, and skin melanin/erythema index, in cigarette smokers. A total of 99 male volunteers were enrolled in this study. Smokers were categorized as light-to-moderate (hydration and skin melanin/erythema index on the dorsal hand, forehead, and cheek. Basal transepidermal water loss (TEWL) and barrier recovery rates were assessed on the forearm. A Skin-pH-Meter pH900 was used to measure skin surface pH. Our results showed that heavy cigarette smokers exhibited delayed barrier recovery after acute abrogation (1.02% ± 13.06 versus 16.48% ± 6.07), and barrier recovery rates correlated negatively with the number of daily cigarettes consumption (p = 0.0087). Changes in biophysical parameters in cigarette smokers varied with body sites. In conclusion, heavy cigarette smokers display compromised permeability barrier homeostasis, which could contribute, in part, to the increased prevalence of certain cutaneous disorders characterized by defective permeability. Thus, improving epidermal permeability barrier should be considered for heavy cigarette smokers. PMID:27437403

Review of potential subsurface permeable barrier emplacement and monitoring technologies

International Nuclear Information System (INIS)

Riggsbee, W.H.; Treat, R.L.; Stansfield, H.J.; Schwarz, R.M.; Cantrell, K.J.; Phillips, S.J.

1994-02-01

This report focuses on subsurface permeable barrier technologies potentially applicable to existing waste disposal sites. This report describes candidate subsurface permeable barriers, methods for emplacing these barriers, and methods used to monitor the barrier performance. Two types of subsurface barrier systems are described: those that apply to contamination.in the unsaturated zone, and those that apply to groundwater and to mobile contamination near the groundwater table. These barriers may be emplaced either horizontally or vertically depending on waste and site characteristics. Materials for creating permeable subsurface barriers are emplaced using one of three basic methods: injection, in situ mechanical mixing, or excavation-insertion. Injection is the emplacement of dissolved reagents or colloidal suspensions into the soil at elevated pressures. In situ mechanical mixing is the physical blending of the soil and the barrier material underground. Excavation-insertion is the removal of a soil volume and adding barrier materials to the space created. Major vertical barrier emplacement technologies include trenching-backfilling; slurry trenching; and vertical drilling and injection, including boring (earth augering), cable tool drilling, rotary drilling, sonic drilling, jetting methods, injection-mixing in drilled holes, and deep soil mixing. Major horizontal barrier emplacement technologies include horizontal drilling, microtunneling, compaction boring, horizontal emplacement, longwall mining, hydraulic fracturing, and jetting methods

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

Measurement of radon permeability through polyethylene membrane using scintillation detector

Energy Technology Data Exchange (ETDEWEB)

Ashry, A.H.; Abou-Leila, M. [Department of Physics, Faculty of Education, Ain Shams University, Cairo (Egypt); Abdalla, A.M., E-mail: aymanabdalla62@hotmail.co [Department of Physics, Faculty of Education, Ain Shams University, Cairo (Egypt); Department of Physics, Faculty of Sciences and Arts, Najran University, Najran, P.O. Box. 11001 (Saudi Arabia); Advanced Materials and Nano-Engineering Laboratory (AMNEL), Centre for Advanced Materials and Nano-Engineering (CAMNE), Najran University, Najran, P.O. Box. 11001 (Saudi Arabia)

2011-01-15

The permeability of Radon 222 through polyethylene membranes has been studied using activated charcoal technique. The permeability constant of Radon 222 through low-density polyethylene, linear low-density Polyethylene and high density polyethylene samples has been measured. There is a considerable agreement between the values obtained by our method and the method suggested by W. Arafa [2002. Permeability of radon 222 through some materials. Radiat. Meas. 35, 207-211], and SSNTD technique suggested by A. Hafez and G. Somogyi [1986. Determination of radon and thoron permeability through some plastics by track technique. Int. J. Radiat. Appl. Instrum. Nucl. Track Radiat. Meas. 12 (1-6), 697-700]. In this work Radon permeability through different polyethylene membranes has been measured using three different methods, i.e. solid state nuclear track technique, W. Arafa [2002. Permeability of radon 222 through some materials. Radiat. Meas. 35, 207-211]method and our proposed method. In addition to this, in this study, the diffusion coefficient of radon in charcoal as well as solubility of Radon in polyethylene membrane has been taken into consideration.

Measurement of radon permeability through polyethylene membrane using scintillation detector

International Nuclear Information System (INIS)

Ashry, A.H.; Abou-Leila, M.; Abdalla, A.M.

2011-01-01

The permeability of Radon 222 through polyethylene membranes has been studied using activated charcoal technique. The permeability constant of Radon 222 through low-density polyethylene, linear low-density Polyethylene and high density polyethylene samples has been measured. There is a considerable agreement between the values obtained by our method and the method suggested by W. Arafa [2002. Permeability of radon 222 through some materials. Radiat. Meas. 35, 207-211], and SSNTD technique suggested by A. Hafez and G. Somogyi [1986. Determination of radon and thoron permeability through some plastics by track technique. Int. J. Radiat. Appl. Instrum. Nucl. Track Radiat. Meas. 12 (1-6), 697-700]. In this work Radon permeability through different polyethylene membranes has been measured using three different methods, i.e. solid state nuclear track technique, W. Arafa [2002. Permeability of radon 222 through some materials. Radiat. Meas. 35, 207-211] method and our proposed method. In addition to this, in this study, the diffusion coefficient of radon in charcoal as well as solubility of Radon in polyethylene membrane has been taken into consideration.

Instrumentation for Measurement of Gas Permeability of Polymeric Membranes

Science.gov (United States)

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

1993-01-01

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

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

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

Water-Permeable Dialysis Membranes for Multi-Layered Micro Dialysis System

Directory of Open Access Journals (Sweden)

Naoya eTo

2015-06-01

Full Text Available This paper presents the development of water-permeable dialysis membranes that are suitable for an implantable microdialysis system that does not use dialysis fluid. We developed a microdialysis system integrating microfluidic channels and nanoporous filtering membranes made of polyethersulfone (PES, aiming at a fully implantable system that drastically improves the quality of life of patients. Simplicity of the total system is crucial for the implantable dialysis system, where the pumps and storage tanks for the dialysis fluid pose problems. Hence, we focus on hemofiltration, which does not require the dialysis fluid but water-permeable membranes. We investigated the water-permeability of the PES membrane with respect to the concentrations of the PES, the additives, and the solvents in the casting solution. Sufficiently water-permeable membranes were found through in vitro experiments using whole bovine blood. The filtrate was verified to have the concentrations of low-molecular-weight molecules, such as sodium, potassium, urea, and creatinine, while proteins, such as albumin, were successfully blocked by the membrane. We conducted in vivo experiments using rats, where the system was connected to the femoral artery and jugular vein. The filtrate was successfully collected without any leakage of blood inside the system and it did not contain albumin but low-molecular-weight molecules whose concentrations were identical to those of the blood. The rat model with renal failure showed 100% increase of creatinine in 5 h, while rats connected to the system showed only a 7.4% increase, which verified the effectiveness of the proposed microdialysis system.

Polybenzimidazole-based mixed membranes with exceptional high water vapor permeability and selectivity

KAUST Repository

Akhtar, Faheem Hassan

2017-09-13

Polybenzimidazole (PBI), a thermal and chemically stable polymer, is commonly used to fabricate membranes for applications like hydrogen recovery at temperatures of more than 300 °C, fuel cells working in a highly acidic environment, and nanofiltration in aggressive solvents. This report shows for the first time use of PBI dense membranes for water vapor/gas separation applications. They showed an excellent selectivity and high water vapor permeability. Incorporation of inorganic hydrophilic titanium-based nano-fillers into the PBI matrix further increased the water vapor permeability and water vapor/N2 selectivity. The most selective mixed matrix membrane with 0.5 wt% loading of TiO2 nanotubes yielded a water vapor permeability of 6.8×104 Barrer and a H2O/N2 selectivity of 3.9×106. The most permeable membrane with 1 wt% loading of carboxylated TiO2 nanoparticles had a 7.1×104 Barrer water vapor permeability and a H2O/N2 selectivity of 3.1×106. The performance of these membranes in terms of water vapor transport and selectivity is among the highest reported ones. The remarkable ability of PBI to efficiently permeate water versus other gases opens the possibility to fabricate membranes for dehumidification of streams in harsh environments. This includes the removal of water from high temperature reaction mixtures to shift the equilibrium towards products.

Polybenzimidazole-based mixed membranes with exceptional high water vapor permeability and selectivity

KAUST Repository

Akhtar, Faheem Hassan; Kumar, Mahendra; Villalobos, Luis Francisco; Shevate, Rahul; Vovusha, Hakkim; Schwingenschlö gl, Udo; Peinemann, Klaus-Viktor

2017-01-01

Polybenzimidazole (PBI), a thermal and chemically stable polymer, is commonly used to fabricate membranes for applications like hydrogen recovery at temperatures of more than 300 °C, fuel cells working in a highly acidic environment, and nanofiltration in aggressive solvents. This report shows for the first time use of PBI dense membranes for water vapor/gas separation applications. They showed an excellent selectivity and high water vapor permeability. Incorporation of inorganic hydrophilic titanium-based nano-fillers into the PBI matrix further increased the water vapor permeability and water vapor/N2 selectivity. The most selective mixed matrix membrane with 0.5 wt% loading of TiO2 nanotubes yielded a water vapor permeability of 6.8×104 Barrer and a H2O/N2 selectivity of 3.9×106. The most permeable membrane with 1 wt% loading of carboxylated TiO2 nanoparticles had a 7.1×104 Barrer water vapor permeability and a H2O/N2 selectivity of 3.1×106. The performance of these membranes in terms of water vapor transport and selectivity is among the highest reported ones. The remarkable ability of PBI to efficiently permeate water versus other gases opens the possibility to fabricate membranes for dehumidification of streams in harsh environments. This includes the removal of water from high temperature reaction mixtures to shift the equilibrium towards products.

Permeability of the blood-brain barrier predicts conversion from optic neuritis to multiple sclerosis

DEFF Research Database (Denmark)

Cramer, Stig P; Modvig, Signe; Simonsen, Helle Juhl

2015-01-01

in the permeability of the blood-brain barrier in normal-appearing white matter of patients with multiple sclerosis and here, for the first time, we present a study on the capability of blood-brain barrier permeability in predicting conversion from optic neuritis to multiple sclerosis and a direct comparison...... with cerebrospinal fluid markers of inflammation, cellular trafficking and blood-brain barrier breakdown. To this end, we applied dynamic contrast-enhanced magnetic resonance imaging at 3 T to measure blood-brain barrier permeability in 39 patients with monosymptomatic optic neuritis, all referred for imaging...... fluid as well as levels of CXCL10 and MMP9 in the cerebrospinal fluid. These findings suggest that blood-brain barrier permeability, as measured by magnetic resonance imaging, may provide novel pathological information as a marker of neuroinflammation related to multiple sclerosis, to some extent...

SURFACE-ALTERED ZEOLITES AS PERMEABLE BARRIERS FOR IN SITU TREATMENT OF CONTAMINATED GROUNDWATER

International Nuclear Information System (INIS)

Bowman, Robert S.; Li, Zhaohui; Roy, Stephen J.; Burt, Todd; Johnson, Timothy L.; Johnson, Richard L.

1999-01-01

The overall objective of this effort is to develop and test a zeolite-based permeable barrier system for containing and remediating contaminated groundwater. The projected product is an engineered and tested permeable barrier system that can be adopted by the commercial sector

SURFACE-ALTERED ZEOLITES AS PERMEABLE BARRIERS FOR IN SITU TREATMENT OF CONTAMINATED GROUNDWATER

Energy Technology Data Exchange (ETDEWEB)

Robert S. Bowman; Zhaohui Li; Stephen J. Roy; Todd Burt; Timothy L. Johnson; Richard L. Johnson

1999-08-30

The overall objective of this effort is to develop and test a zeolite-based permeable barrier system for containing and remediating contaminated groundwater. The projected product is an engineered and tested permeable barrier system that can be adopted by the commercial sector.

Permeable bio-reactive barriers for hydrocarbon remediation in Antarctica

Energy Technology Data Exchange (ETDEWEB)

Mumford, K.A.; Stevens, G.W.; Gore, D.B. [Melbourne Univ., Victoria (Australia). Dept. of Chemical and Biomoleculuar Engineering, Particulate Fluids Processing Centre; Snape, I.; Rayner, J.L. [Australian Antarctic Div., Kingston, Tasmania (Australia); Gore, D.B. [Macquarie Univ., Sydney, NSW (Australia). Dept. of Environmental Science

2010-07-01

This study assessed the performance of a permeable bio-reactive barrier designed to treat contaminated water. The bio-reactive barrier was installed at a fuel spill site located in the Windmill Islands, Antarctica. A funnel and gate design was used to prevent contaminant migration beyond the barrier location as well as to ensure controlled nutrient delivery. The study also investigated the performance of the bio-reactive barrier in regions with freeze-thaw conditions. The 4-year project was also conducted to assess optimal conditions for enhancing the barrier's ability to degrade hydrocarbons.

Exploring bacterial outer membrane barrier to combat bad bugs.

Science.gov (United States)

Ghai, Ishan; Ghai, Shashank

2017-01-01

One of the main fundamental mechanisms of antibiotic resistance in Gram-negative bacteria comprises an effective change in the membrane permeability to antibiotics. The Gram-negative bacterial complex cell envelope comprises an outer membrane that delimits the periplasm from the exterior environment. The outer membrane contains numerous protein channels, termed as porins or nanopores, which are mainly involved in the influx of hydrophilic compounds, including antibiotics. Bacterial adaptation to reduce influx through these outer membrane proteins (Omps) is one of the crucial mechanisms behind antibiotic resistance. Thus to interpret the molecular basis of the outer membrane permeability is the current challenge. This review attempts to develop a state of knowledge pertinent to Omps and their effective role in antibiotic influx. Further, it aims to study the bacterial response to antibiotic membrane permeability and hopefully provoke a discussion toward understanding and further exploration of prospects to improve our knowledge on physicochemical parameters that direct the translocation of antibiotics through the bacterial membrane protein channels.

Recovery of ammonia and phosphate minerals from swine wastewater using gas-permeable membranes

Science.gov (United States)

Gas-permeable membrane technology is useful to recover ammonia from liquid manures. In this study, phosphorus (P) recovery via magnesium chloride precipitation was enhanced by combining it with ammonia recovery through gas-permeable membranes. Anaerobically digested swine effluent containing approx...

Evaluation of synthetic zeolite as engineering passive permeable reactive barrier

International Nuclear Information System (INIS)

Ibrahim, O.A.A.

2011-01-01

The presence of toxic pollutants in groundwater brings about significant changes in the properties of water resources and has to be avoided in order to preserve the environmental quality. Heavy metals are among the most dangerous inorganic water pollutants, that related to many anthropogenic sources and their compounds are extremely toxic. The treatment of contaminated groundwater is among the most difficult and expensive environmental problems. Over the past years, permeable reactive barriers have provided an increasingly important role in the passive insitu treatment of contaminated groundwater. There are a large number of materials that are able to immobilize contaminants by sorption, including granulated active carbon, zeolite, montmorillonite, peat, compost, sawdust, etc. Zeolite X is a synthetic counterpart of the naturally occurring mineral Faujasite. It has one of the largest cavities and cavity entrances of any known zeolites. The main aim of this work is to examine the possibility of using synthetic zeolite X as an engineering permeable reactive barrier to remove heavy metals from a contaminated groundwater. Within this context, the following investigations were carried out: 1. Review on the materials most commonly used as engineered permeable reactive barriers to identify the important features to be considered in the examination of the proposed permeable reactive barrier material (zeolite X). 2. Synthesis of zeolite X and characterization of the synthesized material using different techniques. 3. Batch tests were carried out to characterize the equilibrium and kinetic sorption properties of the synthesized zeolite X towards the concerned heavy metals; zinc and cadmium ions. 4. Column tests were also performed to determine the design factors for permeable reactive barrier against zinc and cadmium ions solutions.Breakthrough curves measured in such experiments used to determine the hydrodynamic dispersion coefficients for both metal ions. 5. Analytical

Patterning of super-hydrophobic structures on permeable sensor membranes

NARCIS (Netherlands)

Pelt, van S.; Eggermont, J.; Frijns, A.J.H.; Dietzel, A.H.; Colin, S; Morini, GL; Brandner, JJ

2012-01-01

For a disposable smart food monitoring system, a gas sensor membrane is needed that isolates the sensor surface from (dust) particles water droplets. At the same time, this membrane must have a high permeability, a sufficiently fast response times and should be water repellent to avoid blocking of

Test device for measuring permeability of a barrier material

Science.gov (United States)

Reese, Matthew; Dameron, Arrelaine; Kempe, Michael

2014-03-04

A test device for measuring permeability of a barrier material. An exemplary device comprises a test card having a thin-film conductor-pattern formed thereon and an edge seal which seals the test card to the barrier material. Another exemplary embodiment is an electrical calcium test device comprising: a test card an impermeable spacer, an edge seal which seals the test card to the spacer and an edge seal which seals the spacer to the barrier material.

Pb2+ Modulates Ca2+ Membrane Permeability In Paramecium

Science.gov (United States)

Bernal-Martínez, Juan; Ortega Soto, Arturo

2004-09-01

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

Extracorporeal membrane oxygenation causes loss of intestinal epithelial barrier in the newborn piglet.

Science.gov (United States)

Kurundkar, Ashish R; Killingsworth, Cheryl R; McIlwain, R Britt; Timpa, Joseph G; Hartman, Yolanda E; He, Dongning; Karnatak, Rajendra K; Neel, Mary L; Clancy, John P; Anantharamaiah, G M; Maheshwari, Akhil

2010-08-01

Extracorporeal membrane oxygenation (ECMO) is an important life-support system used in neonates and young children with intractable cardiorespiratory failure. In this study, we used our porcine neonatal model of venoarterial ECMO to investigate whether ECMO causes gut barrier dysfunction. We subjected 3-wk-old previously healthy piglets to venoarterial ECMO for up to 8 h and evaluated gut mucosal permeability, bacterial translocation, plasma levels of bacterial products, and ultrastructural changes in gut epithelium. We also measured plasma lipopolysaccharide (LPS) levels in a small cohort of human neonates receiving ECMO. In our porcine model, ECMO caused a rapid increase in gut mucosal permeability within the first 2 h of treatment, leading to a 6- to 10-fold rise in circulating bacterial products. These changes in barrier function were associated with cytoskeletal condensation in epithelial cells, which was explained by phosphorylation of a myosin II regulatory light chain. In support of these findings, we also detected elevated plasma LPS levels in human neonates receiving ECMO, indicating a similar loss of gut barrier function in these infants. On the basis of these data, we conclude that ECMO is an independent cause of gut barrier dysfunction and bacterial translocation may be an important contributor to ECMO-related inflammation.

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.

The biofiltration permeable reactive barrier: Practical experience from Synthesia

Energy Technology Data Exchange (ETDEWEB)

Vesela, L.; Nemecek, J.; Siglova, M.; Kubal, M. [DEKONTA, Prague (Czech Republic)

2006-10-15

The paper refers to utilization of biological elements within permeable reactive barriers. The concept of a biofiltration permeable barrier has been tested in the laboratory and in pilot-scale. Oxyhumolite (oxidized young lignite) was examined as an absorption material and a biofilm carrier. Laboratory tests performed before the pilot verification confirmed that oxyhumolite adsorbs organic pollutants at a minimum value, but that it can be used for biofilm attachment. An experimental barrier was built on premises of a chemical factory contaminated mainly by various organic pollutants (benzene, toluene, ethylbenzene, and xylenes (BTEX), chlorobenzenes, naphthalene, nitro-derivatives, phenols, trichloroethylene (TCE), and total petroleum hydrocarbon (TPH)). Before the barrier was installed, a preliminary survey of the unsaturated zone, hydrogeological investigation, and a microbiological survey had been performed. The barrier was designed as a trench-and-gate system with an in situ bioreactor. During the year 2004, measurements of groundwater flux and retention time under current hydrological conditions, together with chemical and microbiological monitoring, were carried out on the site. The results showed high effectiveness of organic contamination removal. Average elimination varied from 57.3% (naphthalene) to 99.9% (nitro-derivatives, BTEX); microbial density in the bioreactor was approx. 10{sup 5} CFU mL{sup -1}.

Improving the performance of water desalination through ultra-permeable functionalized nanoporous graphene oxide membrane

Science.gov (United States)

Hosseini, Mostafa; Azamat, Jafar; Erfan-Niya, Hamid

2018-01-01

Molecular dynamics simulations were performed to investigate the water desalination performance of nanoporous graphene oxide (NPGO) membranes. The simulated systems consist of a NPGO as a membrane with a functionalized pore in its center immersed in an aqueous ionic solution and a graphene sheet as a barrier. The considered NPGO membranes are involved four types of pore with different size and chemistry. The results indicated that the NPGO membrane has effective efficiency in salt rejection as well as high performance in water flux. For all types of pore with the radius size of 2.9-4.5 Å, the NPGO shows salt rejection of >89%. Functional groups on the surface and edge of pores have a great effect on water flux. To precisely understand the effect of functional groups on the surface of nanostructured membranes, nanoporous graphene was simulated under the same condition for comparison. Hydrophilic groups on the surface make the NPGO as an ultra-permeable membrane. As a result, the obtained water flux for NPGO was about 77% greater than graphene. Also, it was found that the water flux of NPGO is 2-5 orders of magnitude greater than other existing reverse osmosis membranes. Therefore, the investigated systems can be recommended as a model for the water desalination.

Hydrogen concentration control utilizing a hydrogen permeable membrane

International Nuclear Information System (INIS)

Keating, S.J. Jr.

1976-01-01

The concentration of hydrogen in a fluid mixture is controlled to a desired concentration by flowing the fluid through one chamber of a diffusion cell separated into two chambers by a hydrogen permeable membrane. A gradient of hydrogen partial pressure is maintained across the membrane to cause diffusion of hydrogen through the membrane to maintain the concentration of hydrogen in the fluid mixture at the predetermined level. The invention has particular utility for the purpose of injecting into and/or separating hydrogen from the reactor coolant of a nuclear reactor system

Control of BTEX migration using a biologically enhanced permeable barrier

International Nuclear Information System (INIS)

Borden, R.C.; Goin, R.T.; Kao, C.M.

1997-01-01

A permeable barrier system, consisting of a line of closely spaced wells, was installed perpendicular to ground water flow to control the migration of a dissolved hydrocarbon plume. The wells were charged with concrete briquets that release oxygen and nitrate at a controlled rate, enhancing aerobic biodegradation in the downgradient aquifer. Laboratory batch reactor experiments were conducted to identify concrete mixtures that slowly released oxygen over an extended time period. A full-scale permeable barrier system using ORC was constructed at a gasoline-spill site. During the first 242 days of operation, total BTEX decreased from 17 to 3.4 mg/L and dissolved oxygen increased from 0.4 to 1.8 mg/L during transport through the barrier. Over time, BTEX treatment efficiencies declined, indicating the barrier system had become less effective in releasing oxygen and nutrients to the highly contaminated portion of the aquifer. Point dilution tests and sediment analyses performed at the conclusion of the project indicated that the aquifer in the vicinity of the remediation wells had been clogged by precipitation with iron minerals

ECONOMICS ANALYSIS OF THE IMPLEMENTATION OF PERMEABLE REACTIVE BARRIERS FOR REMEDIATION OF CONTAMINATED GROUND WATER

Science.gov (United States)

This report presents an analysis of the cost of using permeable reactive barriers to remediate contaminated ground water. When possible, these costs are compared with the cost of pump-and-treat technology for similar situations. Permeable reactive barriers are no longer perceiv...

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+

Exploring bacterial outer membrane barrier to combat bad bugs

Directory of Open Access Journals (Sweden)

Ghai I

2017-08-01

Full Text Available Ishan Ghai,1 Shashank Ghai2 1School of Engineering and Life Sciences, Jacobs University, Bremen, 2Leibniz University, Hannover, Germany Abstract: One of the main fundamental mechanisms of antibiotic resistance in Gram-negative bacteria comprises an effective change in the membrane permeability to antibiotics. The Gram-negative bacterial complex cell envelope comprises an outer membrane that delimits the periplasm from the exterior environment. The outer membrane contains numerous protein channels, termed as porins or nanopores, which are mainly involved in the influx of hydrophilic compounds, including antibiotics. Bacterial adaptation to reduce influx through these outer membrane proteins (Omps is one of the crucial mechanisms behind antibiotic resistance. Thus to interpret the molecular basis of the outer membrane permeability is the current challenge. This review attempts to develop a state of knowledge pertinent to Omps and their effective role in antibiotic influx. Further, it aims to study the bacterial response to antibiotic membrane permeability and hopefully provoke a discussion toward understanding and further exploration of prospects to improve our knowledge on physicochemical parameters that direct the translocation of antibiotics through the bacterial membrane protein channels. Keywords: antibiotics, Gram-negative bacteria, cell envelope, protein channels, nanopores, influx, antibiotic resistance

Permeability measurement of some barrier materials as a function of temperature and pressure

International Nuclear Information System (INIS)

Maqsood, M.; Faisal, S.; Ali, J.; Usman, A.; Alamgir, K.; Farooq, K.

2011-01-01

Barrier materials possess the ability to restrict the passage of gases, vapors, and organic liquids through their boundaries. These barrier materials have large number of applications in industry and scientific research. To measure the permeability of barrier materials, a specific gas flow system has been developed, pure helium gas is used to measure the back ground reading through SS-316. The permeability and break-through time has been measured through Inconel X-750, NBR and Viton below and above the atmospheric pressure and at different temperatures 20 deg. C, 40 deg. C and 70 deg. C. (author)

Experimental Validation of a Permeability Model for Enrichment Membranes

International Nuclear Information System (INIS)

Orellano, Pablo; Brasnarof, Daniel; Florido Pablo

2003-01-01

An experimental loop with a real scale diffuser, in a single enrichment-stage configuration, was operated with air at different process conditions, in order to characterize the membrane permeability.Using these experimental data, an analytical geometric-and-morphologic-based model was validated.It is conclude that a new set of independent measurements, i.e. enrichment, is necessary in order to fully characterize diffusers, because of its internal parameters are not univocally determinated with permeability experimental data only

[Research on ultrasonic permeability of low intensity pulsed ultrasound through PTFE membrane and Bio-Gide collagen membrane].

Science.gov (United States)

Chai, Zhaowu; Zhao, Chunliang; Song, Jinlin; Deng, Feng; Yang, Ji; Gao, Xiang; Liu, Minyi

2013-12-01

The aim of the present study was to detect the transmission rate of ultrasonic low intensity pulsed ultrasound (LIPUS) through polytetrafluoroethylene (PTFE) membrane (Thickness: 0.01 mm) and Bio-Gide collagen membrane, and to provide the basis for the barrier membrane selection on the study of LIPUS combined with guided tissue regeneration (GTR). The ultrasonic (LIPUS, frequency 1.5 MHz, pulse width 200 micros, repetition rate 1.0 kHz) transmission coefficient of the two kinds of barrier membrane were detected respectively through setting ten groups from 10 to 100mW/cm2 every other 10 mW/cm2. We found in the study that the ultrasonic transmission coefficient through 0.01 mm PTFE membrane was 78.1% to 92.%, and the ultrasonic transmission coefficient through Bio-Gide collagen membrane was 43.9% to 55.8%. The ultrasonic transmission coefficient through PTFE membrane was obviously higher than that through Bio-Gide collagen membrane. The transmission coefficient of the same barrier membrane of the ultrasonic ion was statistically different under different powers (P PTFE membrane and Bio-Gide collagen membrane were relatively high. We should select barrier membranes based on different experimental needs, and exercise ultrasonic transmission coefficient experiments to ensure effective power.

Enhancing the intestinal membrane permeability of zanamivir: a carrier mediated prodrug approach.

Science.gov (United States)

Gupta, Sheeba Varghese; Gupta, Deepak; Sun, Jing; Dahan, Arik; Tsume, Yasuhiro; Hilfinger, John; Lee, Kyung-Dall; Amidon, Gordon L

2011-12-05

The purpose of this study was to improve the membrane permeability and oral absorption of the poorly permeable anti-influenza agent, zanamivir. The poor oral bioavailability is attributed to the high polarity (cLogP ∼ -5) resulting from the polar and zwitterionic nature of zanamivir. In order to improve the permeability of zanamivir, prodrugs with amino acids were developed to target the intestinal membrane transporter, hPepT1. Several acyloxy ester prodrugs of zanamivir conjugated with amino acids were synthesized and characterized. The prodrugs were evaluated for their chemical stability in buffers at various pHs and for their transport and tissue activation by enzymes. The acyloxy ester prodrugs of zanamivir were shown to competitively inhibit [(3)H]Gly-Sar uptake in Caco-2 cells (IC(50): 1.19 ± 0.33 mM for L-valyl prodrug of zanamivir). The L-valyl prodrug of zanamivir exhibited ∼3-fold higher uptake in transfected HeLa/hPepT1 cells compared to wild type HeLa cells, suggesting, at least in part, carrier mediated transport by the hPepT1 transporter. Further, enhanced transcellular permeability of prodrugs across Caco-2 monolayer compared to the parent drug (P(app) = 2.24 × 10(-6) ± 1.33 × 10(-7) cm/s for L-valyl prodrug of zanamivir), with only parent zanamivir appearing in the receiver compartment, indicates that the prodrugs exhibited both enhanced transport and activation in intestinal mucosal cells. Most significantly, several of these prodrugs exhibited high intestinal jejunal membrane permeability, similar to metoprolol, in the in situ rat intestinal perfusion system, a system highly correlated with human jejunal permeability. In summary, this mechanistic targeted prodrug strategy, to enhance oral absorption via intestinal membrane carriers such as hPepT1, followed by activation to parent drug (active pharmaceutical ingredient or API) in the mucosal cell, significantly improves the intestinal epithelial cell permeability of zanamivir and has the

Selectively gas-permeable composite membrane and process for production thereof

International Nuclear Information System (INIS)

Okita, K.; Asako, S.

1984-01-01

A selectively gas-permeable composite membrane and a process for producing said composite membrane are described. The composite membrane comprises a polymeric material support and a thin membrane deposited on the support, said thin membrane being obtained by glow discharge plasma polymerization of an organosilane compound containing at least one double bond or triple bond. Alternatively, the composite membrane comprises a polymeric material support having an average pore diameter of at least 0.1 micron, a hardened or cross-linked polyorganosiloxane layer on the support, and a thin membrane on the polyorganosiloxane layer, said thin membrane being obtained by plasma polymerization due to glow discharge of an organosilane compound containing at least one double bond or triple bond

Reactive Membrane Barriers for Containment of Subsurface Contamination

Energy Technology Data Exchange (ETDEWEB)

William A. Arnold; Edward L. Cussler

2007-02-26

The overall goal of this project was to develop reactive membrane barriers--a new and flexible technique to contain and stabilize subsurface contaminants. Polymer membranes will leak once a contaminant is able to diffuse through the membrane. By incorporating a reactive material in the polymer, however, the contaminant is degraded or immobilized within the membrane. These processes increase the time for contaminants to breakthrough the barrier (i.e. the lag time) and can dramatically extend barrier lifetimes. In this work, reactive barrier membranes containing zero-valent iron (Fe{sup 0}) or crystalline silicotitanate (CST) were developed to prevent the migration of chlorinated solvents and cesium-137, respectively. These studies were complemented by the development of models quantifying the leakage/kill time of reactive membranes and describing the behavior of products produced via the reactions within the membranes. First, poly(vinyl alcohol) (PVA) membranes containing Fe{sup 0} and CST were prepared and tested. Although PVA is not useful in practical applications, it allows experiments to be performed rapidly and the results to be compared to theory. For copper ions (Cu{sup 2+}) and carbon tetrachloride, the barrier was effective, increasing the time to breakthrough over 300 times. Even better performance was expected, and the percentage of the iron used in the reaction with the contaminants was determined. For cesium, the CST laden membranes increased lag times more than 30 times, and performed better than theoretical predictions. A modified theory was developed for ion exchangers in reactive membranes to explain this result. With the PVA membranes, the effect of a groundwater matrix on barrier performance was tested. Using Hanford groundwater, the performance of Fe{sup 0} barriers decreased compared to solutions containing a pH buffer and high levels of chloride (both of which promote iron reactivity). For the CST bearing membrane, performance improved by a

Reactive Membrane Barriers for Containment of Subsurface Contamination

International Nuclear Information System (INIS)

William A. Arnold; Edward L. Cussler

2007-01-01

The overall goal of this project was to develop reactive membrane barriers--a new and flexible technique to contain and stabilize subsurface contaminants. Polymer membranes will leak once a contaminant is able to diffuse through the membrane. By incorporating a reactive material in the polymer, however, the contaminant is degraded or immobilized within the membrane. These processes increase the time for contaminants to breakthrough the barrier (i.e. the lag time) and can dramatically extend barrier lifetimes. In this work, reactive barrier membranes containing zero-valent iron (Fe 0 ) or crystalline silicotitanate (CST) were developed to prevent the migration of chlorinated solvents and cesium-137, respectively. These studies were complemented by the development of models quantifying the leakage/kill time of reactive membranes and describing the behavior of products produced via the reactions within the membranes. First, poly(vinyl alcohol) (PVA) membranes containing Fe 0 and CST were prepared and tested. Although PVA is not useful in practical applications, it allows experiments to be performed rapidly and the results to be compared to theory. For copper ions (Cu 2+ ) and carbon tetrachloride, the barrier was effective, increasing the time to breakthrough over 300 times. Even better performance was expected, and the percentage of the iron used in the reaction with the contaminants was determined. For cesium, the CST laden membranes increased lag times more than 30 times, and performed better than theoretical predictions. A modified theory was developed for ion exchangers in reactive membranes to explain this result. With the PVA membranes, the effect of a groundwater matrix on barrier performance was tested. Using Hanford groundwater, the performance of Fe 0 barriers decreased compared to solutions containing a pH buffer and high levels of chloride (both of which promote iron reactivity). For the CST bearing membrane, performance improved by a factor of three when

Mass transfer rate through liquid membranes: interfacial chemical reactions and diffusion as simultaneous permeability controlling factors

International Nuclear Information System (INIS)

Danesi, P.R.; Horwitz, E.P.; Vandegrift, G.F.; Chiarizia, R.

1981-01-01

Equations describing the permeability of a liquid membrane to metal cations have been derived taking into account aqueous diffusion, membrane diffusion, and interfacial chemical reactions as simultaneous permeability controlling factors. Diffusion and chemical reactions have been coupled by a simple model analogous to the one previously described by us to represent liquid-liquid extraction kinetics. The derived equations, which make use of experimentally determined interfacial reaction mechanisms, qualitatively fit unexplained literature data regarding Cu 2+ transfer through liquid membranes. Their use to predict and optimize membrane permeability in practical separation processes by setting the appropriate concentration of the membrane carrier [LIX 64 (General Mills), a commercial β-hydroxy-oxime] and the pH of the aqueous copper feed solution is briefly discussed. 4 figures

Strength and Numerical Analysis in the Design of Permeable Reactive Barriers

Science.gov (United States)

Pawluk, Katarzyna; Wrzesiński, Grzegorz; Lendo-Siwicka, Marzena

2017-10-01

Permeable reactive barriers are one of the most important in situ technologies in groundwater remediation. Most of the installed PRBs have tended to use singular reactive media, but there is an increasing number of applications using combined or sequenced media to treat mixtures of contaminants within a groundwater plume. The concept of a multi-layered permeable reactive barrier (MPRB) to prevent and protect groundwater along traffic routes, especially in ecologically and naturally valuable areas, was developed following several field and laboratory investigations conducted in the Department of Geotechnical Engineering of the Warsaw University of Life Sciences. In accordance with the guidelines of the Interstate Technology & Regulatory Council for the selection of reactive materials, numerous laboratory and field investigations should be performed to determine the environmental conditions, type and concentrations of the contaminants, and the physical-chemical and permeability properties of the reactive materials. However, the deformation and strength properties of the reactive materials should be also considered in the design and evaluation of the safety conditions. In this paper, strength and deformation properties of silica spongolite, zeolite, and activated carbon were investigated using direct shear and oedometer tests. The laboratory test results were used in numerical calculations with the application of the finite element method. The aim of this study was to define the impact of the installation stages of a multi-layered permeable reactive barrier on the stability of a road embankment. Numerical analysis may prevent, reduce or eliminate the risk in the case of a breakdown during the construction or/and exploitation of a PRB.

Gyroid Nanoporous Membranes with Tunable Permeability

DEFF Research Database (Denmark)

Li, Li; Schulte, Lars; Clausen, Lydia D.

2011-01-01

-linked 1,2-polybutadiene (1,2-PB) membranes with uniform pores that, if needed, can be rendered hydrophilic. The gyroid porosity has the advantage of isotropic percolation with no need for structure prealignment. Closed (skin) or opened (nonskin) outer surface can be simply realized by altering...... the effective diffusion coefficients of a series of antibiotics, proteins, and other biomolecules; solute permeation is discussed in terms of hindered diffusion. The combination of uniform bulk morphology, isotropically percolating porosity, controlled surface chemistry, and tunable permeability is distinctive...

Octopus microvasculature: permeability to ferritin and carbon.

Science.gov (United States)

Browning, J

1979-01-01

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

Enhanced recovery of ammonia from swine manure anaerobic digester effluent using gas-permeable membranes and aeration

Science.gov (United States)

Atmospheric ammonia pollution from livestock wastes can be reduced using gas-permeable membrane technology by converting ammonia contained in the manure into ammonium salt for use in fertilizers. In this study, gas-permeable membrane technology was enhanced using aeration combined with nitrificatio...

Micro pore arrays in free standing cyclic olefin copolymer membranes: fabrication and surface functionalization strategies for in-vitro barrier tissue models

Science.gov (United States)

Gel, M.; Kandasamy, S.; Cartledge, K.; Be, C. L.; Haylock, D.

2013-12-01

In recent years there has been growing interest in micro engineered in-vitro models of tissues and organs. These models are designed to mimic the in-vivo like physiological conditions with a goal to study human physiology in an organ-specific context or to develop in-vitro disease models. One of the challenges in the development of these models is the formation of barrier tissues in which the permeability is controlled locally by the tissues cultured at the interface. In-vitro models of barrier tissues are typically created by generating a monolayer of cells grown on thin porous membranes. This paper reports a robust preparation method for free standing porous cyclic olefin copolymer (COC) membranes. We also demonstrate that gelatin coated membranes facilitate formation of highly confluent monolayer of HUVECs. Membranes with thickness in the range of 2-3 um incorporating micro pores with diameter approximately 20 um were fabricated and integrated with microfluidic channels. The performance of the device was demonstrated with a model system mimicking the endothelial barrier in bone marrow sinusoids.

Mapping the Fluid Pathways and Permeability Barriers of a Large Gas Hydrate Reservoir

Science.gov (United States)

Campbell, A.; Zhang, Y. L.; Sun, L. F.; Saleh, R.; Pun, W.; Bellefleur, G.; Milkereit, B.

2012-12-01

An understanding of the relationship between the physical properties of gas hydrate saturated sedimentary basins aids in the detection, exploration and monitoring one of the world's upcoming energy resources. A large gas hydrate reservoir is located in the MacKenzie Delta of the Canadian Arctic and geophysical logs from the Mallik test site are available for the gas hydrate stability zone (GHSZ) between depths of approximately 850 m to 1100 m. The geophysical data sets from two neighboring boreholes at the Mallik test site are analyzed. Commonly used porosity logs, as well as nuclear magnetic resonance, compressional and Stoneley wave velocity dispersion logs are used to map zones of elevated and severely reduced porosity and permeability respectively. The lateral continuity of horizontal permeability barriers can be further understood with the aid of surface seismic modeling studies. In this integrated study, the behavior of compressional and Stoneley wave velocity dispersion and surface seismic modeling studies are used to identify the fluid pathways and permeability barriers of the gas hydrate reservoir. The results are compared with known nuclear magnetic resonance-derived permeability values. The aim of investigating this heterogeneous medium is to map the fluid pathways and the associated permeability barriers throughout the gas hydrate stability zone. This provides a framework for an understanding of the long-term dissociation of gas hydrates along vertical and horizontal pathways, and will improve the knowledge pertaining to the production of such a promising energy source.

Convection due to an unstable density difference across a permeable membrane

Science.gov (United States)

Puthenveettil, Baburaj A.; Arakeri, Jaywant H.

We study natural convection driven by unstable concentration differences of sodium chloride (NaCl) across a horizontal permeable membrane at Rayleigh numbers (Ra) of 1010 to 1011 and Schmidt number (Sc)=600. A layer of brine lies over a layer of distilled water, separated by the membrane, in square-cross-section tanks. The membrane is permeable enough to allow a small flow across it at higher driving potentials. Based on the predominant mode of transport across the membrane, three regimes of convection, namely an advection regime, a diffusion regime and a combined regime, are identified. The near-membrane flow in all the regimes consists of sheet plumes formed from the unstable layers of fluid near the membrane. In the advection regime observed at higher concentration differences (Bb) show a common log-normal probability density function at all Ra. We propose a phenomenology which predicts /line{lambda}_b sqrt{Z_w Z_{V_i}}, where Zw and Z_{V_i} are, respectively, the near-wall length scales in Rayleighnard convection (RBC) and due to the advection velocity. In the combined regime, which occurs at intermediate values of C/2)4/3. At lower driving potentials, in the diffusion regime, the flux scaling is similar to that in turbulent RBC.

Calcium reduces the sodium permeability of luminal membrane vesicles from toad bladder. Studies using a fast-reaction apparatus

International Nuclear Information System (INIS)

Chase, H.S. Jr.; Al-Awqati, Q.

1983-01-01

Regulation of the sodium permeability of the luminal membrane is the major mechanism by which the net rate of sodium transport across tight epithelia is varied. Previous evidence has suggested that the permeability of the luminal membrane might be regulated by changes in intracellular sodium or calcium activities. To test this directly, we isolated a fraction of the plasma membrane from the toad urinary bladder, which contains a fast, amiloride-sensitive sodium flux with characteristics similar to those of the native luminal membrane. Using a flow-quench apparatus to measure the initial rate of sodium efflux from these vesicles in the millisecond time range, we have demonstrated that the isotope exchange permeability of these vesicles is very sensitive to calcium. Calcium reduces the sodium permeability, and the half-maximal inhibitory concentration is 0.5 microM, well within the range of calcium activity found in cells. Also, the permeability of the luminal membrane vesicles is little affected by the ambient sodium concentration. These results, when taken together with studies on whole tissue, suggest that cell calcium may be an important regulator of transepithelial sodium transport by its effect on luminal sodium permeability. The effect of cell sodium on permeability may be mediated by calcium rather than by sodium itself

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.

Calculating the permeability coefficients of mixed matrix membranes of polydimethylsiloxane and silicalite crystals to various ethanol-water solutions using molecular simulations.

Science.gov (United States)

The permeability coefficients of mixed matrix membranes of polydimethylsiloxane (PDMS) and silicalite crystal are taken as the sum of the permeability coefficients of membrane components each weighted by their associated mass fraction. The permeability coefficient of a membrane c...

Astrocyte–endothelial interactions and blood–brain barrier permeability*

Science.gov (United States)

Abbott, N Joan

2002-01-01

The blood–brain barrier (BBB) is formed by brain endothelial cells lining the cerebral microvasculature, and is an important mechanism for protecting the brain from fluctuations in plasma composition, and from circulating agents such as neurotransmitters and xenobiotics capable of disturbing neural function. The barrier also plays an important role in the homeostatic regulation of the brain microenvironment necessary for the stable and co-ordinated activity of neurones. The BBB phenotype develops under the influence of associated brain cells, especially astrocytic glia, and consists of more complex tight junctions than in other capillary endothelia, and a number of specific transport and enzyme systems which regulate molecular traffic across the endothelial cells. Transporters characteristic of the BBB phenotype include both uptake mechanisms (e.g. GLUT-1 glucose carrier, L1 amino acid transporter) and efflux transporters (e.g. P-glycoprotein). In addition to a role in long-term barrier induction and maintenance, astrocytes and other cells can release chemical factors that modulate endothelial permeability over a time-scale of seconds to minutes. Cell culture models, both primary and cell lines, have been used to investigate aspects of barrier induction and modulation. Conditioned medium taken from growing glial cells can reproduce some of the inductive effects, evidence for involvement of diffusible factors. However, for some features of endothelial differentiation and induction, the extracellular matrix plays an important role. Several candidate molecules have been identified, capable of mimicking aspects of glial-mediated barrier induction of brain endothelium; these include TGFβ, GDNF, bFGF, IL-6 and steroids. In addition, factors secreted by brain endothelial cells including leukaemia inhibitory factor (LIF) have been shown to induce astrocytic differentiation. Thus endothelium and astrocytes are involved in two-way induction. Short-term modulation of brain

Electrically Driven Ion Separations in Permeable Membranes

Energy Technology Data Exchange (ETDEWEB)

Bruening, Merlin [Michigan State Univ., East Lansing, MI (United States)

2017-04-21

Membranes are attractive for a wide range of separations due to their low energy costs and continuous operation. To achieve practical fluxes, most membranes consist of a thin, selective skin on a highly permeable substrate that provides mechanical strength. Thus, this project focused on creating new methods for forming highly selective ultrathin skins as well as modeling transport through these coatings to better understand their unprecedented selectivities. The research explored both gas and ion separations, and the latter included transport due to concentration, pressure and electrical potential gradients. This report describes a series of highlights of the research and then provides a complete list of publications supported by the grant. These publications have been cited more than 4000 times. Perhaps the most stunning finding is the recent discovery of monovalent/divalent cation and anion selectivities around 1000 when modifying cation- and anion-exchange membranes with polyelectrolyte multilayers (PEMs). This discovery builds on many years of exciting research. (Citation numbers refer to the journal articles in the bibliography.)

Permeable barrier materials for strontium immobilization: Unsaturated flow apparatus determination of hydraulic conductivity -- Column sorption experiments

International Nuclear Information System (INIS)

Moody, T.E.; Conca, J.

1996-09-01

Selected materials were tested to emulate a permeable barrier and to examine the (1) capture efficiency of these materials relating to the immobilization of strontium-90 and hexavalent chromium (Cr 6+ ) in Hanford Site groundwater; and (2) hydraulic conductivity of the barrier material relative to the surrounding area. The emplacement method investigated was a permeable reactive barrier to treat contaminated groundwater as it passes through the barrier. The hydraulic conductivity function was measured for each material, and retardation column experiments were performed for each material. Measurements determining the hydraulic conductivity at unsaturated through saturated water content were executed using the Unsaturated Flow Apparatus

Selective imipenem resistance in Pseudomonas aeruginosa associated with diminished outer membrane permeability.

OpenAIRE

Studemeister, A E; Quinn, J P

1988-01-01

The permeability of the outer membranes of imipenem-susceptible and imipenem-resistant clinical isolates of Pseudomonas aeruginosa was investigated by the liposome swelling assay. Sugars and cephaloridine penetrated rapidly, whereas imipenem penetrated poorly into liposomes constructed from porin-rich outer membrane fractions of the resistant isolates.

Low Permeable Hydrocarbon Polymer Electrolyte Membrane for Vanadium Redox Flow Battery.

Science.gov (United States)

Jung, Ho-Young; Moon, Geon-O; Jung, Seunghun; Kim, Hee Tak; Kim, Sang-Chai; Roh, Sung-Hee

2017-04-01

Polymer electrolyte membrane (PEM) confirms the life span of vanadium redox flow battery (VRFB). Products from Dupont, Nafion membrane, is mainly used for PEM in VRFB. However, permeation of vanadium ion occurs because of Nafion’s high permeability. Therefore, the efficiency of VRFB decreases and the prices becomes higher, which hinders VRFB’s commercialization. In order to solve this problem, poly(phenylene oxide) (PPO) is sulfonated for the preparation of low-priced hydrocarbon polymer electrolyte membrane. sPPO membrane is characterized by fundamental properties and VRFB cell test.

Proton conducting membranes prepared by incorporation of organophosphorus acids into alcohol barrier polymers for direct methanol fuel cells

Science.gov (United States)

Jiang, Zhongyi; Zheng, Xiaohong; Wu, Hong; Pan, Fusheng

A novel type of DMFC membrane was developed via incorporation of organophosphorus acids (OPAs) into alcohol barrier materials (polyvinyl alcohol/chitosan, PVA/CS) to simultaneously acquire high proton conductivity and low methanol permeability. Three kinds of OPAs including amino trimethylene phosphonic acid (ATMP), ethylene diamine tetra(methylene phosphonic acid) (EDTMP) and hexamethylene diamine tetra(methylene phosphonic acid) (HDTMP), with different molecular structure and phosphonic acid groups content were added into PVA/CS blends and served the dual functions as proton conductor as well as crosslinker. The as-prepared OPA-doped PVA/CS membranes exhibited remarkably enhanced proton conducting ability, 2-4 times higher than that of the pristine PVA/CS membrane, comparable with that for Nafion ®117 membrane (5.04 × 10 -2 S cm -1). The highest proton conductivities 3.58 × 10 -2, 3.51 × 10 -2 and 2.61 × 10 -2 S cm -1 for ATMP-, EDTMP- and HDTMP-doped membranes, respectively were all achieved at highest initial OPA doping content (23.1 wt.%) at room temperature. The EDTMP-doped PVA/CS membrane with an acid content of 13.9 wt.% showed the lowest methanol permeability of 2.32 × 10 -7 cm 2 s -1 which was 16 times lower than that of Nafion ®117 membrane. In addition, the thermal stability and oxidative durability were both significantly improved by the incorporation of OPAs in comparison with pristine PVA/CS membranes.

Stress induces endotoxemia and low-grade inflammation by increasing barrier permeability

Directory of Open Access Journals (Sweden)

Karin ede Punder

2015-05-01

Full Text Available Chronic non-communicable diseases (NCDs are the leading causes of work absence, disability and mortality worldwide. Most of these diseases are associated with low-grade inflammation. Here we hypothesize that stresses (defined as homeostatic disturbances can induce low-grade inflammation by increasing the availability of water, sodium and energy-rich substances to meet the increased metabolic demand induced by the stressor. One way of triggering low-grade inflammation is by increasing intestinal barrier permeability through activation of various components of the stress system. Although beneficial to meet the demands necessary during stress, increased intestinal barrier permeability also raises the possibility of the translocation of bacteria and their toxins across the intestinal lumen into the blood circulation. In combination with modern life-style factors, the increase in bacteria/bacterial toxin translocation arising from a more permeable intestinal wall causes a low-grade inflammatory state. We support this hypothesis with numerous studies finding associations with NCDs and markers of endotoxemia, suggesting that this process plays a pivotal and perhaps even a causal role in the development of low-grade inflammation and its related diseases.

Abnormal blood-brain barrier permeability in normal appearing white matter in multiple sclerosis investigated by MRI

DEFF Research Database (Denmark)

Cramer, Stig Præstekær; Simonsen, Helle Juhl; Frederiksen, Jette Lautrup Battistini

2013-01-01

To investigate whether blood-brain barrier (BBB) permeability is disrupted in normal appearing white matter in MS patients, when compared to healthy controls and whether it is correlated with MS clinical characteristics.......To investigate whether blood-brain barrier (BBB) permeability is disrupted in normal appearing white matter in MS patients, when compared to healthy controls and whether it is correlated with MS clinical characteristics....

PERMEABLE REACTIVE BARRIERS FOR IN-SITU TREATMENT OF ARSENIC-CONTAMINATED GROUNDWATER

Science.gov (United States)

Laboratory and field research has shown that permeable reactive barriers (PRBs) containing a variety of materials can treat arsenic (As) contaminated groundwater. Sites where these PRBs are located include a mine tailings facility, fertilizer and chemical manufacturing sites, a...

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

Science.gov (United States)

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

2017-02-01

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

Exploration of permeability and antifouling performance on modified cellulose acetate ultrafiltration membrane with cellulose nanocrystals.

Science.gov (United States)

Lv, Jinling; Zhang, Guoquan; Zhang, Hanmin; Yang, Fenglin

2017-10-15

Cellulose nanocrystals (CNCs) were introduced into cellulose diacetate (CDA) matrix via immerged phase-inversion process, aiming to improve the filtration and antifouling performance of CNCs/CDA blending membrane. The effects of CNCs on membrane morphologies, hydrophilicity, permeability and antifouling property were investigated. Results showed that the incorporation of CNCs into CDA membrane could effectively enhance the permeability and antifouling property of CNCs/CDA blending membrane by optimizing membrane microstructure and improving membrane hydrophilicity. A high pure water flux of 173.8L/m 2 h was achieved for the CNCs/CDA blending membrane at 200KPa, which is 24 times that of the CDA membrane (7.2L/m 2 h). The bovine serum albumin (BSA) adsorption amount of the CNCs/CDA blending membrane decreased about 48% compared to that of the CDA membrane. Additionally, the CNCs/CDA blending membrane exhibited better antifouling performance with the flux recovery ratio (FRR) of 89.5% after three fouling cycles, compared to 59.7% for the CDA membrane. Copyright © 2017 Elsevier Ltd. All rights reserved.

Microporous membranes from polyamide 6/national clay nanocomposites - Part 2: microstructural and permeability evaluation

International Nuclear Information System (INIS)

Leite, Amanda M.D.; Araujo, Edcleide M.; Lira, Helio de L.; Paz, Rene Anisio da; Medeiros, Vanessa da Nobrega

2014-01-01

Organic/inorganic hybrid membranes of polyamide 6 and mineral clay containing layers of silicate were prepared and compared to those of the pure polymer. Use was made of an as-received sodium clay from industry and another organophilized with ammonium quaternary salts (Dodigen and Cetremide). The salts make the clays surface hydrophobic and improve their incorporation into the polymer matrix in the molten state. Membranes were prepared with these nanocomposites using the immersion-precipitation technique with formic acid as a solvent, and precipitation in a water bath as non-solvent. The acid concentration in the solution containing the polymer and the hybrids was varied to study its influence in morphology and permeability of the membranes. An asymmetric morphology consisting of a filter skin and a porous support was observed, with pores both on the surface and in the cross section being affected by the different salts. This asymmetric morphology was also affected significantly by the acid concentration, with thicker filter skins for higher concentrations. The acid concentration affected the pores size and their distribution. The clay particles probably acted as a barrier to the flow. The permeating flux for the two acid concentrations varied as a function of the distinct morphologies. (author)

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.

Proton conducting membranes prepared by incorporation of organophosphorus acids into alcohol barrier polymers for direct methanol fuel cells

Energy Technology Data Exchange (ETDEWEB)

Jiang, Zhongyi; Zheng, Xiaohong; Wu, Hong; Pan, Fusheng [Key Laboratory for Green Chemical Technology, School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072 (China)

2008-10-15

A novel type of DMFC membrane was developed via incorporation of organophosphorus acids (OPAs) into alcohol barrier materials (polyvinyl alcohol/chitosan, PVA/CS) to simultaneously acquire high proton conductivity and low methanol permeability. Three kinds of OPAs including amino trimethylene phosphonic acid (ATMP), ethylene diamine tetra(methylene phosphonic acid) (EDTMP) and hexamethylene diamine tetra(methylene phosphonic acid) (HDTMP), with different molecular structure and phosphonic acid groups content were added into PVA/CS blends and served the dual functions as proton conductor as well as crosslinker. The as-prepared OPA-doped PVA/CS membranes exhibited remarkably enhanced proton conducting ability, 2-4 times higher than that of the pristine PVA/CS membrane, comparable with that for Nafion {sup registered} 117 membrane (5.04 x 10{sup -2} S cm{sup -1}). The highest proton conductivities 3.58 x 10{sup -2}, 3.51 x 10{sup -2} and 2.61 x 10{sup -2} S cm{sup -1} for ATMP-, EDTMP- and HDTMP-doped membranes, respectively were all achieved at highest initial OPA doping content (23.1 wt.%) at room temperature. The EDTMP-doped PVA/CS membrane with an acid content of 13.9 wt.% showed the lowest methanol permeability of 2.32 x 10{sup -7} cm{sup 2} s{sup -1} which was 16 times lower than that of Nafion {sup registered} 117 membrane. In addition, the thermal stability and oxidative durability were both significantly improved by the incorporation of OPAs in comparison with pristine PVA/CS membranes. (author)

/GD-Tracker/ A software for blood-brain barrier permeability assessment\

Czech Academy of Sciences Publication Activity Database

Kala, David; Svoboda, Jan; Litvinec, Andrej; Pošusta, Antonín; Lisý, J.; Šulc, V.; Tomek, A.; Marusič, P.; Jiruška, Přemysl; Otáhal, Jakub

2017-01-01

Roč. 47, č. 2 (2017), s. 43-48 ISSN 0301-5491 R&D Projects: GA MZd(CZ) NV15-33115A; GA MŠk(CZ) LM2015062 Institutional support: RVO:67985823 Keywords : blood-brain barrier * MRI * Gd-DTPA * permeability * stroke * epileptogenesis * MATLAB * freeware * Gd-Tracker Subject RIV: FH - Neurology OBOR OECD: Neurosciences (including psychophysiology

Carbon-based building blocks for alcohol dehydration membranes with disorder-enhanced water permeability

DEFF Research Database (Denmark)

Boffa, Vittorio; Etmimi, H.; Mallon, P.E.

2017-01-01

Graphene oxide (GO) thin films have demonstrated outstanding water permeability and excellent selectivity towards organic molecules and inorganic salts, unlocking a new exciting direction in the development of nanofiltration, desalination and pervaporation membranes. However, there are still high......-HAL membranes promising devices for alcohol dehydration technologies....

Computational Prediction of Blood-Brain Barrier Permeability Using Decision Tree Induction

Directory of Open Access Journals (Sweden)

Jörg Huwyler

2012-08-01

Full Text Available Predicting blood-brain barrier (BBB permeability is essential to drug development, as a molecule cannot exhibit pharmacological activity within the brain parenchyma without first transiting this barrier. Understanding the process of permeation, however, is complicated by a combination of both limited passive diffusion and active transport. Our aim here was to establish predictive models for BBB drug permeation that include both active and passive transport. A database of 153 compounds was compiled using in vivo surface permeability product (logPS values in rats as a quantitative parameter for BBB permeability. The open source Chemical Development Kit (CDK was used to calculate physico-chemical properties and descriptors. Predictive computational models were implemented by machine learning paradigms (decision tree induction on both descriptor sets. Models with a corrected classification rate (CCR of 90% were established. Mechanistic insight into BBB transport was provided by an Ant Colony Optimization (ACO-based binary classifier analysis to identify the most predictive chemical substructures. Decision trees revealed descriptors of lipophilicity (aLogP and charge (polar surface area, which were also previously described in models of passive diffusion. However, measures of molecular geometry and connectivity were found to be related to an active drug transport component.

Modelling water vapour permeability through atomic layer deposition coated photovoltaic barrier defects

Energy Technology Data Exchange (ETDEWEB)

Elrawemi, Mohamed, E-mail: Mohamed.elrawemi@hud.ac.uk [EPSRC Centre for Innovative Manufacturing in Advanced Metrology, School of Computing and Engineering, University of Huddersfield, Huddersfield (United Kingdom); Blunt, Liam; Fleming, Leigh [EPSRC Centre for Innovative Manufacturing in Advanced Metrology, School of Computing and Engineering, University of Huddersfield, Huddersfield (United Kingdom); Bird, David, E-mail: David.Bird@uk-cpi.com [Centre for Process Innovation Limited, Sedgefield, County Durham (United Kingdom); Robbins, David [Centre for Process Innovation Limited, Sedgefield, County Durham (United Kingdom); Sweeney, Francis [EPSRC Centre for Innovative Manufacturing in Advanced Metrology, School of Computing and Engineering, University of Huddersfield, Huddersfield (United Kingdom)

2014-11-03

Transparent barrier films such as Al{sub 2}O{sub 3} used for prevention of oxygen and/or water vapour permeation are the subject of increasing research interest when used for the encapsulation of flexible photovoltaic modules. However, the existence of micro-scale defects in the barrier surface topography has been shown to have the potential to facilitate water vapour ingress, thereby reducing cell efficiency and causing internal electrical shorts. Previous work has shown that small defects (≤ 3 μm lateral dimension) were less significant in determining water vapour ingress. In contrast, larger defects (≥ 3 μm lateral dimension) seem to be more detrimental to the barrier functionality. Experimental results based on surface topography segmentation analysis and a model presented in this paper will be used to test the hypothesis that the major contributing defects to water vapour transmission rate are small numbers of large defects. The model highlighted in this study has the potential to be used for gaining a better understanding of photovoltaic module efficiency and performance. - Highlights: • A model of water vapour permeation through barrier defects is presented. • The effect of the defects on the water vapour permeability is investigated. • Defect density correlates with water vapour permeability. • Large defects may dominate the permeation properties of the barrier film.

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.

Bile salt-induced increases in duodenal brush-border membrane proton permeability, fluidity, and fragility

International Nuclear Information System (INIS)

Zhao, D.L.; Hirst, B.H.

1990-01-01

Rabbit duodenal brush-border membrane vesicles were treated in vitro with deoxycholate, glycodeoxycholate, or taurodeoxycholate. Intravesicular [14C]glucose space at equilibrium, 0.54 microliters/mg protein, was reduced by exposure to the three bile salts in a concentration (0.1-5.0 mM)-dependent manner, equatable with increased membrane fragility. Net proton permeability (Pnet), determined by acridine orange fluorescence quenching, was increased from 6.3 x 10(-4) cm/sec in untreated vesicles, by approximately 120, 150, and 170%, by treatment with bile salts at 0.1, 0.5 and 1.0 mM, respectively. The three bile salts were equipotent. The increases in membrane fragility and Pnet were not accompanied by significant increases in membrane fluidity, as assessed from steady-state and time-resolved diphenylhexatriene fluorescence anisotropy. The data demonstrate direct effects of bile salts on duodenal apical membrane fragility and proton permeability that are likely to be early events in bile salt-induced mucosal damage

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.

Quasi-equilibrium analysis of the ion-pair mediated membrane transport of low-permeability drugs.

Science.gov (United States)

Miller, Jonathan M; Dahan, Arik; Gupta, Deepak; Varghese, Sheeba; Amidon, Gordon L

2009-07-01

The aim of this research was to gain a mechanistic understanding of ion-pair mediated membrane transport of low-permeability drugs. Quasi-equilibrium mass transport analyses were developed to describe the ion-pair mediated octanol-buffer partitioning and hydrophobic membrane permeation of the model basic drug phenformin. Three lipophilic counterions were employed: p-toluenesulfonic acid, 2-naphthalenesulfonic acid, and 1-hydroxy-2-naphthoic acid (HNAP). Association constants and intrinsic octanol-buffer partition coefficients (Log P(AB)) of the ion-pairs were obtained by fitting a transport model to double reciprocal plots of apparent octanol-buffer distribution coefficients versus counterion concentration. All three counterions enhanced the lipophilicity of phenformin, with HNAP providing the greatest increase in Log P(AB), 3.7 units over phenformin alone. HNAP also enhanced the apparent membrane permeability of phenformin, 27-fold in the PAMPA model, and 4.9-fold across Caco-2 cell monolayers. As predicted from a quasi-equilibrium analysis of ion-pair mediated membrane transport, an order of magnitude increase in phenformin flux was observed per log increase in counterion concentration, such that log-log plots of phenformin flux versus HNAP concentration gave linear relationships. These results provide increased understanding of the underlying mechanisms of ion-pair mediated membrane transport, emphasizing the potential of this approach to enable oral delivery of low-permeability drugs.

A computational assessment of the permeability and salt rejection of carbon nanotube membranes and their application to water desalination

Science.gov (United States)

Thomas, Michael; Corry, Ben

2016-01-01

Membranes made from nanomaterials such as nanotubes and graphene have been suggested to have a range of applications in water filtration and desalination, but determining their suitability for these purposes requires an accurate assessment of the properties of these novel materials. In this study, we use molecular dynamics simulations to determine the permeability and salt rejection capabilities for membranes incorporating carbon nanotubes (CNTs) at a range of pore sizes, pressures and concentrations. We include the influence of osmotic gradients and concentration build up and simulate at realistic pressures to improve the reliability of estimated membrane transport properties. We find that salt rejection is highly dependent on the applied hydrostatic pressure, meaning high rejection can be achieved with wider tubes than previously thought; while membrane permeability depends on salt concentration. The ideal size of the CNTs for desalination applications yielding high permeability and high salt rejection is found to be around 1.1 nm diameter. While there are limited energy gains to be achieved in using ultra-permeable CNT membranes in desalination by reverse osmosis, such membranes may allow for smaller plants to be built as is required when size or weight must be minimized. There are diminishing returns in further increasing membrane permeability, so efforts should focus on the fabrication of membranes containing narrow or functionalized CNTs that yield the desired rejection or selection properties rather than trying to optimize pore densities. PMID:26712639

Recovery of ammonia and production of high-grade phosphates from side-stream digester effluents using gas-permeable membranes

Science.gov (United States)

Phosphorus recovery was combined with ammonia recovery using gas-permeable membranes. In a first step, the ammonia and alkalinity were removed from municipal side-stream wastewater using low-rate aeration and a gas-permeable membrane manifold. In a second step, the phosphorus was removed using magne...

Coxsackievirus protein 2B modifies endoplasmic reticulum membrane and plasma membrane permeability and facilitates virus release.

Science.gov (United States)

van Kuppeveld, F J; Hoenderop, J G; Smeets, R L; Willems, P H; Dijkman, H B; Galama, J M; Melchers, W J

1997-01-01

Digital-imaging microscopy was performed to study the effect of Coxsackie B3 virus infection on the cytosolic free Ca2+ concentration and the Ca2+ content of the endoplasmic reticulum (ER). During the course of infection a gradual increase in the cytosolic free Ca2+ concentration was observed, due to the influx of extracellular Ca2+. The Ca2+ content of the ER decreased in time with kinetics inversely proportional to those of viral protein synthesis. Individual expression of protein 2B was sufficient to induce the influx of extracellular Ca2+ and to release Ca2+ from ER stores. Analysis of mutant 2B proteins showed that both a cationic amphipathic alpha-helix and a second hydrophobic domain in 2B were required for these activities. Consistent with a presumed ability of protein 2B to increase membrane permeability, viruses carrying a mutant 2B protein exhibited a defect in virus release. We propose that 2B gradually enhances membrane permeability, thereby disrupting the intracellular Ca2+ homeostasis and ultimately causing the membrane lesions that allow release of virus progeny. PMID:9218794

Permeability of EVOH Barrier Material Used in Automotive Applications: Metrology Development for Model Fuel Mixtures

Directory of Open Access Journals (Sweden)

Zhao Jing

2015-02-01

Full Text Available EVOH (Ethylene-Vinyl Alcohol materials are widely used in automotive applications in multi-layer fuel lines and tanks owing to their excellent barrier properties to aromatic and aliphatic hydrocarbons. These barrier materials are essential to limit environmental fuel emissions and comply with the challenging requirements of fast changing international regulations. Nevertheless, the measurement of EVOH permeability to model fuel mixtures or to their individual components is particularly difficult due to the complexity of these systems and their very low permeability, which can vary by several orders of magnitude depending on the permeating species and their relative concentrations. This paper describes the development of a new automated permeameter capable of taking up the challenge of measuring minute quantities as low as 1 mg/(m2.day for partial fluxes for model fuel mixtures containing ethanol, i-octane and toluene at 50°C. The permeability results are discussed as a function of the model fuel composition and the importance of EVOH preconditioning is emphasized for accurate permeability measurements. The last part focuses on the influence of EVOH conditioning on its mechanical properties and its microstructure, and further illustrates the specific behavior of EVOH in presence of ethanol oxygenated fuels. The new metrology developed in this work offers a new insight in the permeability properties of a leading barrier material and will help prevent the consequences of (bioethanol addition in fuels on environmental emissions through fuel lines and tanks.

Ph responsive permeability and Ion- exchange characteristics of (PE/EPDM)-g-PMAA membranes

International Nuclear Information System (INIS)

El- Awady, M.M.; El-Awady, N.I.; Eissa, A.M.

2005-01-01

Chemical grafting of methacrylic acid (MAA) on low density exchange membranes for recovery of different cations from their solutions was investigated. When the dialysis permeability of two solutes (glucose + urea) through the membrane were tested at different ph values and compared, glucose was found to be less efficient than urea for permeation through the membrane. The permeability response of such solute was noticed only at higher ph value (ph 8). The grafted film (membrane) with graft yield of 185% is experimentally adequate to permeate all molecules with radius of lower than 4.3 x 10 polyethylene blended with EPDM with a ratio (90/10) films was carried out using sodium bisulphite as initiator. Factors affecting grafting and the properties of the grafted films were studied in details and showed improved hydrophilic properties, good thermal stability and nearly unaffected strength properties which make them acceptable for practical uses.In the present work, the possibility of practical uses of such grafted films as ph-responsive membranes in a dialysis process and as ion--7 mm. Grafted membranes in different forms (COOH-form), (Na-methacrylate form) and (K methacrylate- form) were prepared to evaluate the membranes uptake selectivity to different mono, di-and trivalent cations from their solutions. The results obtained showed very good efficiency of the prepared membranes as compared with the values obtained for the commercial cation exchange resin (Dowex)

Achieving high permeability and enhanced selectivity for Angstrom-scale separations using artificial water channel membranes.

Science.gov (United States)

Shen, Yue-Xiao; Song, Woochul C; Barden, D Ryan; Ren, Tingwei; Lang, Chao; Feroz, Hasin; Henderson, Codey B; Saboe, Patrick O; Tsai, Daniel; Yan, Hengjing; Butler, Peter J; Bazan, Guillermo C; Phillip, William A; Hickey, Robert J; Cremer, Paul S; Vashisth, Harish; Kumar, Manish

2018-06-12

Synthetic polymer membranes, critical to diverse energy-efficient separations, are subject to permeability-selectivity trade-offs that decrease their overall efficacy. These trade-offs are due to structural variations (e.g., broad pore size distributions) in both nonporous membranes used for Angstrom-scale separations and porous membranes used for nano to micron-scale separations. Biological membranes utilize well-defined Angstrom-scale pores to provide exceptional transport properties and can be used as inspiration to overcome this trade-off. Here, we present a comprehensive demonstration of such a bioinspired approach based on pillar[5]arene artificial water channels, resulting in artificial water channel-based block copolymer membranes. These membranes have a sharp selectivity profile with a molecular weight cutoff of ~ 500 Da, a size range challenging to achieve with current membranes, while achieving a large improvement in permeability (~65 L m -2  h -1  bar -1  compared with 4-7 L m -2  h -1  bar -1 ) over similarly rated commercial membranes.

Surfactant-modified zeolites as permeable barriers to organic and inorganic groundwater contaminants

International Nuclear Information System (INIS)

Bowman, R.S.; Sullivan, E.J.

1995-01-01

We have shown in laboratory experiments that natural zeolites treated with hexadecyltrimethylammonium (HDTMA) are effective sorbents for nonpolar organics, inorganic cations, and inorganic anions. Due to their low cost (∼$0.75/kg) and granular nature, HDTMA-zeolites appear ideal candidates for reactive, permeable subsurface barriers. The HDTMA-zeolites are stable over a wide range of pH (3-13), ionic strength (1 M Cs + or Ca 2+ ), and in organic solvents. Surfactant-modified zeolites sorb nonpolar organics (benzene, toluene, xylene, chlorinated aliphatics) via a partitioning mechanism, inorganic cations (Pb 2+ ) via ion exchange and surface complexation, and inorganic anions (CrO 4 2- , SeO 4 2- , SO 4 2- ) via surface precipitation.The goal of this work is to demonstrate the use of surfactant-modified zeolite as a permeable barrier to ground water contaminants

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.

The diffusion permeability to water of the rat blood-brain barrier

DEFF Research Database (Denmark)

Bolwig, T G; Lassen, N A

1975-01-01

The diffusion permeability to water of the rat blood-brain-barrier (BBB) was studied. Preliminary data obtained with the Oldendorf tissue uptake method (Oldendorf 1970) in seizure experiments suggested that the transfer from blood to brain of labelled water is diffusion-limited. More definite...... passage increased from 0.26 to 0.67 when the arterial carbon dioxide tension was changed from 15 to 85 mm Hg, a change increasing the cerebral blood flow about sixfold. This finding suggests that water does not pass the blood-brain barrier as freely as lipophilic gases....

Abatement of ammonia emissions from digested manure using gas-permeable membranes

Science.gov (United States)

A new strategy to avoid ammonia emissions from anaerobically digested swine manure was tested using the gas-permeable membrane process. Evaluation of the efficiency of ammonia recovery from digestate as well as mitigation of ammonia emissions to the atmosphere were carried out. Digestate was colle...

Research on Permeability of Poly(ethylene) Terephthalate Track Membranes Modified in Plasma

CERN Document Server

Dmitriev, S N; Sleptsov, V V; Elinson, V M; Potrjasaj, V V

2001-01-01

The properties of poly(ethylene) terephthalate track membranes subjected to the plasma RF-discharge treatment in air have been investigated. The effect of the treatment conditions in plasma on the structure and the properties of the membranes formed in the gas-discharge etching has been studied. It has been figured out that the influence of the air plasma on the membranes under study leads to a formation of asymmetric membranes with a higher flow rate, the structure and chemical composition of their superficial layer are changed. It is shown that the presence of the modified layer on the surface of the membranes causes changing their hydrodynamic characteristics - water permeability of the membranes treated in plasma in a greater degree depends upon {pH} of the filtered solution.

Diffusion studies on permeable nitroxyl spin probe through lipid bilayer membrane

International Nuclear Information System (INIS)

Benial, A. Milton Franklin; Meenakumari, V.; Ichikawa, Kazuhiro; Yamada, Ken-ichi; Utsumi, Hideo; Hyodo, Fuminori; Jawahar, A.

2014-01-01

Electron spin resonance (ESR) studies were carried out for 2mM 14 N labeled deutrated permeable 3- methoxycarbonyl-2,2,5,5-tetramethyl-pyrrolidine-1-oxyl (MC-PROXYL) in pure water, 1 mM, 2 mM, 3 mM and 4 mM concentration of MC-PROXYL in 300 mM concentration of liposomal solution by using a L-band ESR spectrometer. The ESR parameters such as linewidth, hyperfine coupling constant, g-factor, partition parameter and permeability were reported. The partition parameter and permeability values indicate the maximum spin distribution in the lipid phase at 2 mM concentration. This study illustrates that ESR can be used to differentiate between the intra and extra-membrane water by loading the liposome vesicles with a lipid-permeable nitroxyl spin probe. From the ESR results, the radical concentration was optimized as 2 mM in liposomal solution for ESR phantom studies and experiments

Polyethersulfone/clay membranes and its water permeability

International Nuclear Information System (INIS)

Cavalho, Thamyres Cardoso de; Medeiros, Vanessa da Nobrega; Araujo, Edcleide Maria de; Lira, Helio Lucena; Leite, Amanda Melissa Damiao

2017-01-01

Membranes can be considered polymeric or inorganic films that function as a semipermeable barrier to filtration on a molecular scale, separating two phases and restricting, totally or partially, the transportation of one or more chemical species (solute) present in the solution. Therefore, the aim of this work is to produce polyethersulfone membranes (PES) and polyethersulfone/clay by phase inversion technique and evaluate the presence of clay in obtaining membranes for wastewater treatment. The used solvent was dimethylformamide (DMF) and clays were Brasgel PA (MMT) and Cloisite Na (CL Na) in the proportion of 3 to 5% (wt.). By Xray diffraction (XRD), the membranes with 3% of MMT and CL Na clays apparently had partially exfoliated structures. For the composition with 5% of CL Na a small peak was observed, which indicates that this is possibly an intercalated structure or microcomposite. By scanning electron microscopy (SEM), visualizes that the pure surface of the pure PES membrane a structure apparently without pores was observed in the used magnification and without roughness surface when compared to membranes with clay. The measurements of contact angle indicated that the inclusion of clay altered the wetting ability of the membranes. The flow with distilled water for all membranes started high and over time reached a stabilization level. Thus, it can be concluded that the presence and the content of clay altered the morphology of the membrane, contributing to an increase in water flow. (author)

Modulation of ocular surface glycocalyx barrier function by a galectin-3 N-terminal deletion mutant and membrane-anchored synthetic glycopolymers.

Directory of Open Access Journals (Sweden)

Jerome Mauris

Full Text Available BACKGROUND: Interaction of transmembrane mucins with the multivalent carbohydrate-binding protein galectin-3 is critical to maintaining the integrity of the ocular surface epithelial glycocalyx. This study aimed to determine whether disruption of galectin-3 multimerization and insertion of synthetic glycopolymers in the plasma membrane could be used to modulate glycocalyx barrier function in corneal epithelial cells. METHODOLOGY/PRINCIPAL FINDINGS: Abrogation of galectin-3 biosynthesis in multilayered cultures of human corneal epithelial cells using siRNA, and in galectin-3 null mice, resulted in significant loss of corneal barrier function, as indicated by increased permeability to the rose bengal diagnostic dye. Addition of β-lactose, a competitive carbohydrate inhibitor of galectin-3 binding activity, to the cell culture system, transiently disrupted barrier function. In these experiments, treatment with a dominant negative inhibitor of galectin-3 polymerization lacking the N-terminal domain, but not full-length galectin-3, prevented the recovery of barrier function to basal levels. As determined by fluorescence microscopy, both cellobiose- and lactose-containing glycopolymers incorporated into apical membranes of corneal epithelial cells, independently of the chain length distribution of the densely glycosylated, polymeric backbones. Membrane incorporation of cellobiose glycopolymers impaired barrier function in corneal epithelial cells, contrary to their lactose-containing counterparts, which bound to galectin-3 in pull-down assays. CONCLUSIONS/SIGNIFICANCE: These results indicate that galectin-3 multimerization and surface recognition of lactosyl residues is required to maintain glycocalyx barrier function at the ocular surface. Transient modification of galectin-3 binding could be therapeutically used to enhance the efficiency of topical drug delivery.

Impedance-based cell monitoring: barrier properties and beyond

Directory of Open Access Journals (Sweden)

Benson Kathrin

2013-01-01

Full Text Available Abstract In multicellular organisms epithelial and endothelial cells form selective permeable interfaces between tissue compartments of different chemical compositions. Tight junctions which connect adjacent cells, control the passage of molecules across the barrier and, in addition, facilitate active transport processes. The cellular barriers are not static but can be deliberately modulated by exposure to specific external stimuli. In vitro models representing the essential absorption barriers of the body are nowadays available, thus allowing investigation of the parameters that control permeability as well as transport processes across those barriers. Independent of the origin of the barrier forming cells, techniques are needed to quantify their barrier integrity. One simple assay is to measure the permeability for given hydrophilic substrates possessing different molecular weights like sucrose or dextrans. However, this technique is time-consuming and labor-intensive. Moreover, radioactive or fluorescently-labeled substrates are needed to allow easy analytical detection. Finally, if transport processes are investigated, the standard permeant may interfere with the transport process under investigation or might even alter the barrier integrity by itself. Thus, independent, non-invasive techniques are needed to quantify the barrier integrity continuously during the experiment. Such techniques are available and are mainly based on the measurement of the transendothelial or transepithelial electrical resistance (TEER of barrier forming cells grown on porous membranes. Simple devices using two sets of electrodes (so-called Voltohmeters are widely used. In addition, an easy-to-use physical technique called impedance spectroscopy allows the continuous analysis of both the TEER and the electrical capacitance giving additional information about the barrier properties of cells grown on permeable membranes. This technique is useful as a quality control

The rights and wrongs of blood-brain barrier permeability studies

DEFF Research Database (Denmark)

Saunders, Norman R; Dreifuss, Jean-Jacques; Dziegielewska, Katarzyna M

2014-01-01

Careful examination of relevant literature shows that many of the most cherished concepts of the blood-brain barrier are incorrect. These include an almost mythological belief in its immaturity that is unfortunately often equated with absence or at least leakiness in the embryo and fetus....... The original concept of a blood-brain barrier is often attributed to Ehrlich; however, he did not accept that permeability of cerebral vessels was different from other organs. Goldmann is often credited with the first experiments showing dye (trypan blue) exclusion from the brain when injected systemically......, but not when injected directly into it. Rarely cited are earlier experiments of Bouffard and of Franke who showed methylene blue and trypan red stained all tissues except the brain. The term "blood-brain barrier" "Blut-Hirnschranke" is often attributed to Lewandowsky, but it does not appear in his papers...

An in vitro transport model for rapid screening and predicting the permeability of candidate compounds at blood-brain barrier.

Science.gov (United States)

Yang, Zhi-Hong; Sun, Xiao; Mei, Chao; Sun, Xiao-Bo; Liu, Xiao-Dong; Chang, Qi

2011-12-01

The aim of this study was to design and develop a simple in vitro blood-brain barrier (BBB) permeation model for elementarily and rapidly predicting the permeability of candidate compounds at BBB and further evaluating whether P-glycoprotein (P-gp) affects them across BBB. The model was mainly composed of cultured rat brain microvascular endothelial cells (rBMECs), glass contraption, and micropore membrane. First, we evaluated the model by morphological observation. Second, the restriction effects of paracellular transport were verified by measuring marker probes transport, and monitoring transendothelial electrical resistance (TEER) and leakage. Finally, protein expression and activity of P-gp were confirmed by carrying out Western blot analysis and polarized transport of rhodamine-123 (Rho123) in rBMECs. The rBMECs retained both endothelial cells and BBB features. The rBMECs model reproducibly attained approximately 130 Ω cm² on the steady-state TEER value, and displayed a barrier function to marker probes transport by decreasing the permeability. Protein band of 170 kDa manifested the existence of P-gp in the rBMECs, and the findings of cyclosporin A-sensitive decrease of Rho123 efflux confirmed the presence of P-gp activity. A simple, rapid, and convenient in vitro BBB permeation model was successfully established and applied to evaluate the BBB transport profiles of three natural flavonoids: quercetin, naringenin, and rutin.

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).

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.

The casting and mechanism of formation of semi-permeable polymer membranes in a microgravity environment

Science.gov (United States)

Vera, I.

The National Electric Company of Venezuela, C.A.D.A.F.E., is sponsoring the development of this experiment which represents Venezuela's first scientific experiment in space. The apparatus for the automatic casting of polymer thin films will be contained in NASA's payload No. G-559 of the Get Away Special program for a future orbital space flight in the U.S. Space Shuttle. Semi-permeable polymer membranes have important applications in a variety of fields, such as medecine, energy, and pharmaceuticals, and in general fluid separation processes such as reverse osmosis, ultra-filtration, and electro-dialysis. The casting of semi-permeable membranes in space will help to identify the roles of convection in determining the strucutre of these membranes.

Myxoviruses do not induce non-specific alterations in membrane permeability early on in infection

International Nuclear Information System (INIS)

Foster, K.A.; Micklem, K.J.; Bogomolova, N.N.; Boriskin, Y.S.; Pasternak, C.A.

1983-01-01

The permeability characteristics of cells infected with myxoviruses have been studied by measuring the concentrative uptake of nutrients, the concentration of intracellular K + , and the maintenance of the Na + gradient across the plasma membrane. Cells either show no change at all (Sendai virus-infected BHK cells and measles virus-infected Vero cells) or they show a decreased ability to concentrate nutrients, while intracellular K + and the Na + gradient remain unchanged (Sendai and influenza virus-infected L-1210 cells, measles virus-infected lymphocytes and mumps virus-infected L-41 cells). In no case, therefore, was a change observed that resembles the non-specific increase in membrane permeability induced by haemolytic paramyxoviruses (35, 42) or the non-specific membrane leakiness postulated to take place in infected cells (8, 9). A preliminary account of some of these findings has been presented (39)

Research on permeability of poly(ethylene) terephthalate track membranes modified in plasma

International Nuclear Information System (INIS)

Dmitriev, S.N.; Kravets, L.I.; Sleptsov, V.V.; Elinson, V.M.; Potryasaj, V.V.

2001-01-01

The properties of poly(ethylene) terephthalate track membranes subjected to the plasma RF-discharge treatment in air have been investigated. The effect of the treatment conditions in plasma on the structure and the properties of the membranes formed in the gas-discharge etching has been studied. It has been figured out that the influence of the air plasma on the membranes under study leads to a formation of asymmetric membranes with a higher flow rate, the structure and chemical composition of their superficial layer are changed. It is shown that the presence of the modified layer on the surface of the membranes causes changing their hydrodynamic characteristics - water permeability of the membranes treated in plasma in a greater degree depends upon pH of the filtered solution. (author)

Practical Application of Sheet Lead for Sound Barriers.

Science.gov (United States)

Lead Industries Association, New York, NY.

Techniques for improving sound barriers through the use of lead sheeting are described. To achieve an ideal sound barrier a material should consist of the following properties--(1) high density, (2) freedom from stiffness, (3) good damping capacity, and (4) integrity as a non-permeable membrane. Lead combines these desired properties to a greater…

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

Acrolein Disrupts Tight Junction Proteins and Causes Endoplasmic Reticulum Stress-Mediated Epithelial Cell Death Leading to Intestinal Barrier Dysfunction and Permeability.

Science.gov (United States)

Chen, Wei-Yang; Wang, Min; Zhang, Jingwen; Barve, Shirish S; McClain, Craig J; Joshi-Barve, Swati

2017-12-01

Increasing evidence suggests that environmental and dietary factors can affect intestinal epithelial integrity leading to gut permeability and bacterial translocation. Intestinal barrier dysfunction is a pathogenic process associated with many chronic disorders. Acrolein is an environmental and dietary pollutant and a lipid-derived endogenous metabolite. The impact of acrolein on the intestine has not been investigated before and is evaluated in this study, both in vitro and in vivo. Our data demonstrate that oral acrolein exposure in mice caused damage to the intestinal epithelial barrier, resulting in increased permeability and subsequently translocation of bacterial endotoxin-lipopolysaccharide into the blood. Similar results were seen in vitro using established Caco-2 cell monolayers wherein acrolein decreased barrier function and increased permeability. Acrolein also caused the down-regulation and/or redistribution of three representative tight junction proteins (ie, zonula occludens-1, Occludin, Claudin-1) that critically regulate epithelial paracellular permeability. In addition, acrolein induced endoplasmic reticulum stress-mediated death of epithelial cells, which is an important mechanism contributing to intestinal barrier damage/dysfunction, and gut permeability. Overall, we demonstrate that exposure to acrolein affects the intestinal epithelium by decrease/redistribution of tight junction proteins and endoplasmic reticulum stress-mediated epithelial cell death, thereby resulting in loss of barrier integrity and function. Our findings highlight the adverse consequences of environmental and dietary pollutants on intestinal barrier integrity/function with relevance to gut permeability and the development of disease. Copyright © 2017 American Society for Investigative Pathology. Published by Elsevier Inc. All rights reserved.

Fluorescein isothiocyanate (FITC)-Dextran Extravasation as a Measure of Blood-Brain Barrier Permeability

Science.gov (United States)

Natarajan, Reka; Northrop, Nicole

2017-01-01

The blood-brain barrier (BBB) is formed in part by vascular endothelial cells that constitute the capillaries and microvessels of the brain. The function of this barrier is to maintain homeostasis within the brain microenvironment and buffer the brain from changes in the periphery. A dysfunction of the BBB would permit circulating molecules and pathogens typically restricted to the periphery to enter the brain and interfere with normal brain function. As increased permeability of the BBB is associated with several neuropathologies, it is important to have a reliable and sensitive method that determines BBB permeability and the degree of BBB disruption. A detailed protocol is presented for assessing the integrity of the BBB by transcardial perfusion of a 10,000 Da FITC labeled dextran molecule and its visualization to determine the degree of extravasation from brain microvessels. PMID:28398646

Dynamic behaviour of a flexible membrane tsunami Barrier with Dyneema®

NARCIS (Netherlands)

Hofland, B.; Marissen, R.; Bergsma, O.K.

2016-01-01

Proof-of-concept model tests on a novel self-deploying on-shore tsunami barrier were executed. The tsunami barrier consists of a membrane, floater and cables that are stored underground. Due to buoyancy the barrier self-deploys when struck by a tsunami. The membrane and cables consist of the strong,

EDTA-assisted phytoextraction of heavy metals by turfgrass from municipal solid waste compost using permeable barriers and associated potential leaching risk.

Science.gov (United States)

Zhao, Shulan; Lian, Fei; Duo, Lian

2011-01-01

A column experiment with horizontal permeable barriers was conducted to investigate phytoextraction of heavy metals by Lolium perenne L. from municipal solid waste compost following EDTA application, as well as to study the effects of L. perenne and permeable barriers on preventing metal from leaching. In columns with barriers, EDTA addition yielded maximum concentrations of Cu, Zn and Pb of 155, 541 and 33.5 mg kg(-1) in shoot, respectively. This led to 4.2, 2.1 and 7.4 times higher concentrations of Cu, Zn and Pb compared to treatment with no chelating agent, respectively. In treatments with 10 mmol kg(-1) EDTA, the barriers reduced leaching of Cu, Zn and Pb by approximately three times, respectively, resulting in leaching of total initial Cu, Zn and Pb by 27.3%, 25.2% and 28.8%, respectively, after four times' irrigation. These results indicate that L. perenne and permeable barriers are effective to reduce leaching of heavy metals and minimize the risk of contaminating groundwater in EDTA-enhanced phytoremediation. Thus these findings highlight that turfgrass and permeable barriers can effectively prevent metal leaching. Copyright © 2010 Elsevier Ltd. All rights reserved.

The Mechanisms and Quantification of the Selective Permeability in Transport Across Biological Barriers : the Example of Kyotorphin

NARCIS (Netherlands)

Serrano, Isa D.; Freire, Joao M.; Carvalho, Miguel V.; Neves, Mafalda; Melo, Manuel N.; Castanho, Miguel A. R. B.

2014-01-01

This paper addresses the mechanisms behind selective endothelial permeability and their regulations. The singular properties of each of the seven blood-tissues barriers. Then, it further revisits the physical, quantitative meaning of permeability, and the way it should be measured based on sound

Knockout of MIMP protein in lactobacillus plantarum lost its regulation of intestinal permeability on NCM460 epithelial cells through the zonulin pathway.

Science.gov (United States)

Liu, Zhihua; Kang, Liang; Li, Chao; Tong, Chao; Huang, Meijin; Zhang, Xingwei; Huang, Nanqi; Moyer, Mary Pat; Qin, Huanlong; Wang, Jianping

2014-10-03

Previous studies indicated that the micro integral membrane protein located within the media place of the integral membrane protein of Lactobacillus plantarum CGMCC 1258 had protective effects against the intestinal epithelial injury. In our study, we mean to establish micro integral membrane protein -knockout Lactobacillus plantarum (LPKM) to investigate the change of its protective effects and verify the role of micro integral membrane protein on protection of normal intestinal barrier function. Binding assay and intestinal permeability were performed to verify the protective effects of micro integral membrane protein on intestinal permeability in vitro and in vivo. Molecular mechanism was also determined as the zonulin pathway. Clinical data were also collected for further verification of relationship between zonulin level and postoperative septicemia. LPKM got decreased inhibition of EPEC adhesion to NCM460 cells. LPKM had lower ability to alleviate the decrease of intestinal permeability induced by enteropathogenic-e.coli, and prevent enteropathogenic-e.coli -induced increase of zonulin expression. Overexpression of zonulin lowered the intestinal permeability regulated by Lactobacillus plantarum. There was a positive correlation between zonulin level and postoperative septicemia. Therefore, micro integral membrane protein could be necessary for the protective effects of Lactobacillus plantarum on intestinal barrier. MIMP might be a positive factor for Lactobacillus plantarum to protect the intestinal epithelial cells from injury, which could be related to the zonulin pathway.

Permeable Barrier Materials for Strontium Immobilization: - UFA Determination of Hydraulic Conductivity. - Column Sorption Experiments

National Research Council Canada - National Science Library

Moody, T

1996-01-01

Selected materials were tested to emulate a permeable barrier and to examine the: (1) capture efficiency of these materials relating to the immobilization of strontium-90 and hexavalent chromium in Hanford groundwater...

Blood brain barrier permeability and tPA-mediated neurotoxicity

Science.gov (United States)

Nassar, Taher; Yarovoi, Sergey; Rayan, Anwar; Lamensdorf, Itschak; Karakoveski, Michael; Vadim, Polianski; Fanne, Rami Abu; Jamal, Mahmud; Cines, Douglas B.; Higazi, Abd Al-Roof

2015-01-01

Tissue type plasminogen activator (tPA) induces neuronal apoptosis, disrupt the blood-brain-barrier (BBB), and promotes dilation of the cerebral vasculature. The timing, sequence and contributions of these and other deleterious effects of tPA and their contribution to post-ischemic brain damage after stroke, have not been fully elucidated. To dissociate the effects of tPA on BBB permeability, cerebral vasodilation and protease-dependent pathways, we developed several tPA mutants and PAI-1 derived peptides constructed by computerized homology modeling of tPA. Our data show that intravenous administration of human tPA to rats increases BBB permeability through a non-catalytic process, which is associated with reversible neurotoxicity, brain damage, edema, mortality and contributes significantly to its brief therapeutic window. Furthermore, our data show that inhibiting the effect of tPA on BBB function without affecting its catalytic activity, improves outcome and significantly extends its therapeutic window in mechanical as well as thromboembolic models of stroke. PMID:20060006

Permeability and Selectivity of PPO/Graphene Composites as Mixed Matrix Membranes for CO2 Capture and Gas Separation

Directory of Open Access Journals (Sweden)

Riccardo Rea

2018-01-01

Full Text Available We fabricated novel composite (mixed matrix membranes based on a permeable glassy polymer, Poly(2,6-dimethyl-1,4-phenylene oxide (PPO, and variable loadings of few-layer graphene, to test their potential in gas separation and CO2 capture applications. The permeability, selectivity and diffusivity of different gases as a function of graphene loading, from 0.3 to 15 wt %, was measured at 35 and 65 °C. Samples with small loadings of graphene show a higher permeability and He/CO2 selectivity than pure PPO, due to a favorable effect of the nanofillers on the polymer morphology. Higher amounts of graphene lower the permeability of the polymer, due to the prevailing effect of increased tortuosity of the gas molecules in the membrane. Graphene also allows dramatically reducing the increase of permeability with temperature, acting as a “stabilizer” for the polymer matrix. Such effect reduces the temperature-induced loss of size-selectivity for He/N2 and CO2/N2, and enhances the temperature-induced increase of selectivity for He/CO2. The study confirms that, as observed in the case of other graphene-based mixed matrix glassy membranes, the optimal concentration of graphene in the polymer is below 1 wt %. Below such threshold, the morphology of the nanoscopic filler added in solution affects positively the glassy chains packing, enhancing permeability and selectivity, and improving the selectivity of the membrane at increasing temperatures. These results suggest that small additions of graphene to polymers can enhance their permselectivity and stabilize their properties.

The food contaminant deoxynivalenol, decreases intestinal barrier permeability and reduces claudin expression

International Nuclear Information System (INIS)

Pinton, Philippe; Nougayrede, Jean-Philippe; Del Rio, Juan-Carlos; Moreno, Carolina; Marin, Daniela E.; Ferrier, Laurent; Bracarense, Ana-Paula; Kolf-Clauw, Martine; Oswald, Isabelle P.

2009-01-01

'The gastrointestinal tract represents the first barrier against food contaminants as well as the first target for these toxicants. Deoxynivalenol (DON) is a mycotoxin that commonly contaminates cereals and causes various toxicological effects. Through consumption of contaminated cereals and cereal products, human and pigs are exposed to this mycotoxin. Using in vitro, ex vivo and in vivo approaches, we investigated the effects of DON on the intestinal epithelium. We demonstrated that, in intestinal epithelial cell lines from porcine (IPEC-1) or human (Caco-2) origin, DON decreases trans-epithelial electrical resistance (TEER) and increases in a time and dose-dependent manner the paracellular permeability to 4 kDa dextran and to pathogenic Escherichia coli across intestinal cell monolayers. In pig explants treated with DON, we also observed an increased permeability of intestinal tissue. These alterations of barrier function were associated with a specific reduction in the expression of claudins, which was also seen in vivo in the jejunum of piglets exposed to DON-contaminated feed. In conclusion, DON alters claudin expression and decreases the barrier function of the intestinal epithelium. Considering that high levels of DON may be present in food or feed, consumption of DON-contaminated food/feed may induce intestinal damage and has consequences for human and animal health.

Synthesis and deposition of basement membrane proteins by primary brain capillary endothelial cells in a murine model of the blood-brain barrier.

Science.gov (United States)

Thomsen, Maj Schneider; Birkelund, Svend; Burkhart, Annette; Stensballe, Allan; Moos, Torben

2017-03-01

The brain vascular basement membrane is important for both blood-brain barrier (BBB) development, stability, and barrier integrity and the contribution hereto from brain capillary endothelial cells (BCECs), pericytes, and astrocytes of the BBB is probably significant. The aim of this study was to analyse four different in vitro models of the murine BBB for expression and possible secretion of major basement membrane proteins from murine BCECs (mBCECs). mBCECs, pericytes and glial cells (mainly astrocytes and microglia) were prepared from brains of C57BL/6 mice. The mBCECs were grown as monoculture, in co-culture with pericytes or mixed glial cells, or as a triple-culture with both pericytes and mixed glial cells. The integrity of the BBB models was validated by measures of transendothelial electrical resistance (TEER) and passive permeability to mannitol. The expression of basement membrane proteins was analysed using RT-qPCR, mass spectrometry and immunocytochemistry. Co-culturing mBCECs with pericytes, mixed glial cells, or both significantly increased the TEER compared to the monoculture, and a low passive permeability was correlated with high TEER. The mBCECs expressed all major basement membrane proteins such as laminin-411, laminin-511, collagen [α1(IV)] 2 α2(IV), agrin, perlecan, and nidogen 1 and 2 in vitro. Increased expression of the laminin α5 subunit correlated with the addition of BBB-inducing factors (hydrocortisone, Ro 20-1724, and pCPT-cAMP), whereas increased expression of collagen IV α1 primarily correlated with increased levels of cAMP. In conclusion, BCECs cultured in vitro coherently form a BBB and express basement membrane proteins as a feature of maturation. Cover Image for this issue: doi: 10.1111/jnc.13789. © 2016 International Society for Neurochemistry.

Evaluation of the Membrane Permeability (PAMPA and Skin) of Benzimidazoles with Potential Cannabinoid Activity and their Relation with the Biopharmaceutics Classification System (BCS)

OpenAIRE

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

2011-01-01

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 thes...

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...

Research on water permeability of poly(ethylene) terephthalate track membranes modified with plasma

International Nuclear Information System (INIS)

Kravets, L.I.; Dmitriev, S.N.; Sleptsov, V.V.; Elinson, V.M.; Potryasay, V.V.

2001-01-01

The properties of poly(ethylene) terephthalate track membranes subjected to effect of plasma of the RF-discharge in air have been investigated. The influence conditions of a plasma treatment on the surface properties and hydrodynamic characteristics of the membranes has been studied. It has been found that the effect of the air plasma on the researched membranes results in a formation of asymmetric track membranes with a higher flow rate, the structure and chemical composition of their superficial layer are changed. It was shown that the availability of the modified layer on the membrane surface caused changing in their hydrodynamic characteristics - the water permeability of the membranes, processed in plasma, in a greater degree depends upon pH of a filtered solution. (author)

Effect of Adsorbed Protein on the Hydraulic Permeability, Membrane and Streaming Potential Values Measured across a Microporous Membrane

DEFF Research Database (Denmark)

Benavente, Juana; Jonsson, Gunnar Eigil

1998-01-01

permeability decreases strongly when the pH decreases, having its minimum value at the isoelectric point of the protein; the apparent zeta potential values are also dependent on both pH and salt concentration. Differences in the streaming potential coefficient determined for two membranes fouled under......The effect of the adsorption of a protein, bovine serum albumin (BSA), on the membrane potential, flux reduction and streaming potential measured across a microporous polysulphone membrane with different NaCl solutions and pH values is studied. From electrokinetic phenomena, information about...... the electrical properties of the membrane (fixed charge concentration and ionic transport numbers) or the membrane/solute interactions (streaming and zeta potentials) can be obtained. The influence of pH and ionic strength on volume flux and streaming potential values is considered. Results show that hydraulic...

Recovery of ammonia from poultry litter using flat gas permeable membranes.

Science.gov (United States)

Rothrock, M J; Szögi, A A; Vanotti, M B

2013-06-01

The use of flat gas-permeable membranes was investigated as components of a new process to capture and recover ammonia (NH3) in poultry houses. This process includes the passage of gaseous NH3 through a microporous hydrophobic membrane, capture with a circulating dilute acid on the other side of the membrane, and production of a concentrated ammonium (NH4) salt. Bench- and pilot-scale prototype systems using flat expanded polytetrafluoroethylene (ePTFE) membranes and a sulfuric acid solution consistently reduced headspace NH3 concentrations from 70% to 97% and recovered 88% to 100% of the NH3 volatilized from poultry litter. The potential benefits of this technology include cleaner air inside poultry houses, reduced ventilation costs, and a concentrated liquid ammonium salt that can be used as a plant nutrient solution. Published by Elsevier Ltd.

Effects of temperature and anion species on CO2 permeability and CO2/N2 separation coefficient through ionic liquid membranes

International Nuclear Information System (INIS)

Jindaratsamee, Pinyarat; Shimoyama, Yusuke; Morizaki, Hironobu; Ito, Akira

2011-01-01

The permeability of carbon dioxide (CO 2 ) through imidazolium-based ionic liquid membranes was measured by a sweep gas method. Six species of ionic liquids were studied in this work as follows: [emim][BF 4 ], [bmim][BF 4 ], [bmim][PF 6 ], [bmim][Tf 2 N], [bmim][OTf], and [bmim][dca]. The ionic liquids were supported with a polyvinylidene fluoride porous membrane. The measurements were performed at T = (303.15 to 343.15) K. The partial pressure difference between feed and permeate sides was 0.121 MPa. The permeability of the CO 2 increases with temperature for the all ionic liquid species. Base on solution diffusion theory, it can be explained that the diffusion coefficient of CO 2 in an ionic liquid affects the temperature dependence more strongly than the solubility coefficient. The greatest permeability was obtained with the [bmim][Tf 2 N] membrane. The membrane of [bmim][PF 6 ] presents the lowest permeability. The separation coefficient between CO 2 and N 2 through the ionic liquid membranes was also investigated at the volume fraction of CO 2 at feed side 0.10. The separation coefficient decreases with the increase of temperature for the all ionic liquid species. The membrane of [emim][BF 4 ] and [bmim][BF 4 ] gives the highest separation coefficient at constant temperature. The lowest separation coefficient was obtained from [bmim][Tf 2 N] membrane which presents the highest permeability of CO 2 .

Use of novel permeable membrane and air cathodes in acetate microbial fuel cells

Energy Technology Data Exchange (ETDEWEB)

Pant, Deepak, E-mail: deepak.pant@vito.b [Separation and Conversion Technology, VITO - Flemish Institute for Technological Research, Boeretang 200, Mol 2400 (Belgium); Van Bogaert, Gilbert; De Smet, Mark; Diels, Ludo; Vanbroekhoven, Karolien [Separation and Conversion Technology, VITO - Flemish Institute for Technological Research, Boeretang 200, Mol 2400 (Belgium)

2010-11-01

In the existing microbial fuel cells (MFCs), the use of platinized electrodes and Nafion as proton exchange membrane (PEM) leads to high costs leading to a burden for wastewater treatment. In the present study, two different novel electrode materials are reported which can replace conventional platinized electrodes and can be used as very efficient oxygen reducing cathodes. Further, a novel membrane which can be used as an ion permeable membrane (Zirfon) can replace Nafion as the membrane of choice in MFCs. The above mentioned gas porous electrodes were first tested in an electrochemical half cell configuration for their ability to reduce oxygen and later in a full MFC set up. It was observed that these non-platinized air electrodes perform very well in the presence of acetate under MFC conditions (pH 7, room temperature) for oxygen reduction. Current densities of -0.43 mA cm{sup -2} for a non-platinized graphite electrode and -0.6 mA cm{sup -2} for a non-platinized activated charcoal electrode at -200 mV vs. Ag/AgCl of applied potential were obtained. The proposed ion permeable membrane, Zirfonwas tested for its oxygen mass transfer coefficient, K{sub 0} which was compared with Nafion. The K{sub 0} for Zirfon was calculated as 1.9 x 10{sup -3} cm s{sup -1}.

Relating transport modeling to nanofiltration membrane fabrication: Navigating the permeability-selectivity trade-off in desalination pretreatment

OpenAIRE

Labban, Omar; Lienhard, John H

2018-01-01

Faced with a pressing need for membranes with a higher permeability and selectivity, the field of membrane technology can benefit from a systematic framework for designing membranes with the necessary physical characteristics. In this work, we present an approach through which transport modeling is employed in fabricating specialized nanofiltration membranes, that experimentally demonstrate enhanced selectivity. Specifically, the Donnan-Steric Pore Model with dielectric exclusion (DSPM-DE) is...

Positive zeta potential of a negatively charged semi-permeable plasma membrane

Science.gov (United States)

Sinha, Shayandev; Jing, Haoyuan; Das, Siddhartha

2017-08-01

The negative charge of the plasma membrane (PM) severely affects the nature of moieties that may enter or leave the cells and controls a large number of ion-interaction-mediated intracellular and extracellular events. In this letter, we report our discovery of a most fascinating scenario, where one interface (e.g., membrane-cytosol interface) of the negatively charged PM shows a positive surface (or ζ) potential, while the other interface (e.g., membrane-electrolyte interface) still shows a negative ζ potential. Therefore, we encounter a completely unexpected situation where an interface (e.g., membrane-cytosol interface) that has a negative surface charge density demonstrates a positive ζ potential. We establish that the attainment of such a property by the membrane can be ascribed to an interplay of the nature of the membrane semi-permeability and the electrostatics of the electric double layer established on either side of the charged membrane. We anticipate that such a membrane property can lead to such capabilities of the cell (in terms of accepting or releasing certain kinds of moieties as well regulating cellular signaling) that was hitherto inconceivable.

Gas-permeable hydrophobic tubular membranes for ammonia recovery in bio-electrochemical systems

NARCIS (Netherlands)

Kuntke, P.; Zamora, P.; Saakes, M.; Buisman, C.J.N.; Hamelers, H.V.M.

2016-01-01

The application of a gas-permeable hydrophobic tubular membrane in bio-electrochemical systems enables efficient recovery of ammonia (NH₃) from their cathode compartments. Due to a hydrogen evolution reaction at the cathode, no chemical addition was required to increase the pH for

Treatment of radioactive liquid wastes on semi-permeable membranes

International Nuclear Information System (INIS)

Antonescu, M.; Deleanu, N.; Nechifor, G.

1997-01-01

At present, among the currently world-wide applied separation processes, those using membranes are thought to be most advanced due to their advantages: high efficiency, cost-effectiveness in application, universality of the utilized equipment, operation in non-destructive and non-polluting conditions. The most significant results of the treatment experiments are: - a reduction of more than 70% in the chemical oxygen consumption for the solution simulating the POD waste; - the solution simulating the secondary waste from decontamination by POD procedure, appear to be the best (with retentions of 88.5%, 76.5% and 65.7% for strontium, cobalt and manganese, respectively). Important reduction of costs and efficient technological schemes can be obtained by combining the semi-permeable membrane separation techniques with other efficient currently used procedures of separation, concentration and purification, adequate for given situations

Enhancement of Gene Silencing Effect and Membrane Permeability by Peptide-Conjugated 27-Nucleotide Small Interfering RNA

Directory of Open Access Journals (Sweden)

Toshio Seyama

2012-09-01

Full Text Available Two different sizes of siRNAs, of which one type was 21-nucleotide (nt siRNA containing 2-nt dangling ends and the other type was 27-nt siRNA with blunt ends, were conjugated with a nuclear export signal peptide of HIV-1 Rev at the 5′-sense end. Processing by Dicer enzyme, cell membrane permeability, and RNAi efficiency of the peptide-conjugated siRNAs were examined. Dicer cleaved the peptide-conjugated 27-nt siRNA leading to the release of 21-nt siRNA, whereas the peptide-conjugated 21-nt siRNA was not cleaved. High membrane permeability and cytoplasmic localization was found in the conjugates. Moreover, the peptide-conjugated 27-nt siRNA showed increased potency of RNAi in comparison with the nonmodified 21-nt and 27-nt siRNAs, whereas the peptide-conjugated 21-nt siRNA showed decreased RNAi efficacy. This potent RNAi efficacy is probably owing to acceleration of RISC through recognition by Dicer, as well as to the improvement of cell membrane permeability and intracellular accumulation.

Pannexin 1 channels mediate 'find-me' signal release and membrane permeability during apoptosis.

Science.gov (United States)

Chekeni, Faraaz B; Elliott, Michael R; Sandilos, Joanna K; Walk, Scott F; Kinchen, Jason M; Lazarowski, Eduardo R; Armstrong, Allison J; Penuela, Silvia; Laird, Dale W; Salvesen, Guy S; Isakson, Brant E; Bayliss, Douglas A; Ravichandran, Kodi S

2010-10-14

Apoptotic cells release 'find-me' signals at the earliest stages of death to recruit phagocytes. The nucleotides ATP and UTP represent one class of find-me signals, but their mechanism of release is not known. Here, we identify the plasma membrane channel pannexin 1 (PANX1) as a mediator of find-me signal/nucleotide release from apoptotic cells. Pharmacological inhibition and siRNA-mediated knockdown of PANX1 led to decreased nucleotide release and monocyte recruitment by apoptotic cells. Conversely, PANX1 overexpression enhanced nucleotide release from apoptotic cells and phagocyte recruitment. Patch-clamp recordings showed that PANX1 was basally inactive, and that induction of PANX1 currents occurred only during apoptosis. Mechanistically, PANX1 itself was a target of effector caspases (caspases 3 and 7), and a specific caspase-cleavage site within PANX1 was essential for PANX1 function during apoptosis. Expression of truncated PANX1 (at the putative caspase cleavage site) resulted in a constitutively open channel. PANX1 was also important for the 'selective' plasma membrane permeability of early apoptotic cells to specific dyes. Collectively, these data identify PANX1 as a plasma membrane channel mediating the regulated release of find-me signals and selective plasma membrane permeability during apoptosis, and a new mechanism of PANX1 activation by caspases.

Oxidation of trichloroethylene, toluene, and ethanol vapors by a partially saturated permeable reactive barrier

Science.gov (United States)

Mahmoodlu, Mojtaba G.; Hassanizadeh, S. Majid; Hartog, Niels; Raoof, Amir

2014-08-01

The mitigation of volatile organic compound (VOC) vapors in the unsaturated zone largely relies on the active removal of vapor by ventilation. In this study we considered an alternative method involving the use of solid potassium permanganate to create a horizontal permeable reactive barrier for oxidizing VOC vapors. Column experiments were carried out to investigate the oxidation of trichloroethylene (TCE), toluene, and ethanol vapors using a partially saturated mixture of potassium permanganate and sand grains. Results showed a significant removal of VOC vapors due to the oxidation. We found that water saturation has a major effect on the removal capacity of the permeable reactive layer. We observed a high removal efficiency and reactivity of potassium permanganate for all target compounds at the highest water saturation (Sw = 0.6). A change in pH within the reactive layer reduced oxidation rate of VOCs. The use of carbonate minerals increased the reactivity of potassium permanganate during the oxidation of TCE vapor by buffering the pH. Reactive transport of VOC vapors diffusing through the permeable reactive layer was modeled, including the pH effect on the oxidation rates. The model accurately described the observed breakthrough curve of TCE and toluene vapors in the headspace of the column. However, miscibility of ethanol in water in combination with produced water during oxidation made the modeling results less accurate for ethanol. A linear relationship was found between total oxidized mass of VOC vapors per unit volume of permeable reactive layer and initial water saturation. This behavior indicates that pH changes control the overall reactivity and longevity of the permeable reactive layer during oxidation of VOCs. The results suggest that field application of a horizontal permeable reactive barrier can be a viable technology against upward migration of VOC vapors through the unsaturated zone.

A Tracer Test to Characterize Treatment of TCE in a Permeable Reactive Barrier

Science.gov (United States)

A tracer test was conducted to characterize the flow of ground water surrounding a permeable reactive barrier constructed with plant mulch (a biowall) at the OU-1 site on Altus Air Force Base, Oklahoma. This biowall is intended to intercept and treat ground water contaminated by ...

Silver ions increase plasma membrane permeability through modulation of intracellular calcium levels in tobacco BY-2 cells.

Science.gov (United States)

Klíma, Petr; Laňková, Martina; Vandenbussche, Filip; Van Der Straeten, Dominique; Petrášek, Jan

2018-05-01

Silver ions increase plasma membrane permeability for water and small organic compounds through their stimulatory effect on plasma membrane calcium channels, with subsequent modulation of intracellular calcium levels and ion homeostasis. The action of silver ions at the plant plasma membrane is largely connected with the inhibition of ethylene signalling thanks to the ability of silver ion to replace the copper cofactor in the ethylene receptor. A link coupling the action of silver ions and cellular auxin efflux has been suggested earlier by their possible direct interaction with auxin efflux carriers or by influencing plasma membrane permeability. Using tobacco BY-2 cells, we demonstrate here that besides a dramatic increase of efflux of synthetic auxins 2,4-dichlorophenoxyacetic acid (2,4-D) and 1-naphthalene acetic acid (NAA), treatment with AgNO 3 resulted in enhanced efflux of the cytokinin trans-zeatin (tZ) as well as the auxin structural analogues tryptophan (Trp) and benzoic acid (BA). The application of AgNO 3 was accompanied by gradual water loss and plasmolysis. The observed effects were dependent on the availability of extracellular calcium ions (Ca 2+ ) as shown by comparison of transport assays in Ca 2+ -rich and Ca 2+ -free buffers and upon treatment with inhibitors of plasma membrane Ca 2+ -permeable channels Al 3+ and ruthenium red, both abolishing the effect of AgNO 3 . Confocal microscopy of Ca 2+ -sensitive fluorescence indicator Fluo-4FF, acetoxymethyl (AM) ester suggested that the extracellular Ca 2+ availability is necessary to trigger the response to silver ions and that the intracellular Ca 2+ pool alone is not sufficient for this effect. Altogether, our data suggest that in plant cells the effects of silver ions originate from the primal modification of the internal calcium levels, possibly by their interaction with Ca 2+ -permeable channels at the plasma membrane.

Use of jet grouting to create a low permeability horizontal barrier below an incinerator ash landfill

International Nuclear Information System (INIS)

Furth, A.J.; Burke, G.K.; Deutsch, W.L. Jr.

1997-01-01

The City of Philadelphia's Division of Aviation (DOA) has begun construction of a new commuter runway, designated as Runway 8-26, at the Philadelphia International Airport. A portion of this runway will be constructed over a former Superfund site known as the Enterprise Avenue Landfill, which for many years was used to dispose of solid waste incinerator ash and other hazardous materials. The site was clay capped in the 1980's, but in order for the DOA to use the site, additional remediation was needed to meet US EPA final closure requirements. One component of the closure plan included installation of a low permeability horizontal barrier above a very thin (approximately 0.61 to 0.91 meters) natural clay stratum which underlies an approximately 1020 m 2 area of the landfill footprint so as to insure that a minimum 1.52 meter thick low permeability barrier exists beneath the entire 150,000 m 2 landfill. The new barrier was constructed using jet grouting techniques to achieve remote excavation and replacement of the bottom 0.91 meters of the waste mass with a low permeability grout. The grout was formulated to meet the low permeability, low elastic modulus and compressive strength requirements of the project design. This paper will discuss the advantages of using jet grouting for the work and details the development of the grout mixture, modeling of the grout zone under load, field construction techniques, performance monitoring and verification testing

ABOUT CORRELATION BETWEEN THE PERCOLATION RATE OF MOISTURE THROUGH THE SEMI-PERMEABLE MEMBRANES AND THE STANDARD MEASUREMENTS OF THEIR PERMEABILITY OR EVAPORATIVE RESISTANCE

Directory of Open Access Journals (Sweden)

В.Б. Роганков

2015-02-01

Full Text Available A variety of test methods to estimate the water vapour transmission (WVT-rate of thin membranes do not provide, unfortunately, the reliable basis to compare the permeability of different fabrics. Their results are crucially dependent on the details and construction of experimental methodologies as well as on the accepted by the different authors conditions of measurement. In this work, we propose the universal approach and demonstrate its adequate realization to compare the transport properties of any semi-permeable membranes measured by the conventional test-methods. The purpose is to avoid any confusion in such procedure of comparison. We have analysed below the WVT-rates measured by six alternative test-methods, which have been applied step-by-step to six different fabrics. In opposite to the widespread search for a pair correlation between the above results obtained by any two methods we treat them, in total, for each fabric in terms of the reduced variables. This approach is based on the novel concept of the moisture percolation (MP-rate which combines the diffusion and convective contributions in a transport process. It leads to the well-established general estimates of the normalized WVT-rates measured by the standard test-methods. Another advantage of the developed approach is its thermodynamic consistency, which offers the appropriate fluctuation model to take into account the porosity of any semi-permeable membranes.

Tuning biomimetic membrane barrier properties by hydrocarbon, cholesterol and polymeric additives

DEFF Research Database (Denmark)

Palanco, Marta Espina; Skovgaard, Nils; Hansen, Jesper Søndergaard

2017-01-01

The barrier properties of cellular membranes are increasingly attracting attention as a source of inspiration for designing biomimetic membranes. The broad range of potential technological applications makes the use of lipid and lately also polymeric materials a popular choice for constructing...... biomimetic membranes, where the barrier properties can be controlled by the composition of the membrane constituent elements. Here we investigate the membrane properties reported by the light-induced proton pumping activity of bacteriorhodopsin (bR) reconstituted in three vesicle systems of different...... membrane composition. Specifically we quantify how the resulting proton influx and efflux rates are influenced by the membrane composition using a variety of membrane modulators. We demonstrate that by adding hydrocarbons to vesicles with reconstituted bR formed from asolectin lipids the resulting...

Assessment of peritoneal membrane permeability by Tc-99m-excretion in patients undergoing CAPD

International Nuclear Information System (INIS)

Das, B.K.; Senthilnathan, M.S.; Pradhan, P.K.; Jeloka, T.K.; Sharma, R.K.

2002-01-01

Full text: Among various conservative treatment modalities for end stage renal disease (ESRD), continuous ambulatory peritoneal dialysis (CAPD) is increasingly being used in many centers. The success of CAPD depends largely on the permeable characteristics of the peritoneal membrane. Peritoneal Equilibration Test (PET), first described by Twardowski in 1987, is the most commonly used method for determination of peritoneal membrane characteristics. However, this test has several limitations. In order to find an alternative method for assessing peritoneal membrane characteristics we undertook this prospective study involving 20 patients. The main objective was to determine whether peritoneal excretion of intravenously applied Tc-99m-DTPA can be used for this purpose. 20 patients undergoing regular CAPD were included in this study. 370 MBq (10 mCi) of Tc-99m-DTPA was injected intravenously in the same standard preconditions as for the PET evaluation. A standard dose of 370 MBq (10 mCi) DTPA was kept and used later for calculations. At the end of 4 hours, a dialysate fluid sample was collected and the total dialysis effluent volume was measured. Excretion of Tc-99m-DTPA into the dialysate fluid as percentage of injected dose was calculated. Simultaneously standard PET values were determined. The peritoneal excretion of Tc-99m-DTPA ranged from 8 to 16 % of the injected dose depending upon the peritoneal membrane permeability. The patients were divided into following four groups depending upon DTPA excretion. High transporters (15 % and above); high average(12-15 %); low average (10-12 %); low transporters (10 % and less). When the results were compared with standard PET values, a good correlation could be established. We conclude that the radioisotope method using Tc-99m-DTPA can a good alternative technique to assess peritoneal membrane permeability. (author)

Captura de amonio procedente de estiercol mediante membranas permeables de gases (capture of ammonnia from turkey manure using gas-permeable membranes)

Science.gov (United States)

This paper, written in Spanish, describes the capture and recovery of gaseous ammonia from turkey manure using gas-permeable membranes technology with formation of stabilized ammonium salts. Bench experiments were carried out in Maryland using a pilot prototype system with turkey litter inside contr...

Capsid protein VP4 of human rhinovirus induces membrane permeability by the formation of a size-selective multimeric pore.

Directory of Open Access Journals (Sweden)

Anusha Panjwani

2014-08-01

Full Text Available Non-enveloped viruses must deliver their viral genome across a cell membrane without the advantage of membrane fusion. The mechanisms used to achieve this remain poorly understood. Human rhinovirus, a frequent cause of the common cold, is a non-enveloped virus of the picornavirus family, which includes other significant pathogens such as poliovirus and foot-and-mouth disease virus. During picornavirus cell entry, the small myristoylated capsid protein VP4 is released from the virus, interacts with the cell membrane and is implicated in the delivery of the viral RNA genome into the cytoplasm to initiate replication. In this study, we have produced recombinant C-terminal histidine-tagged human rhinovirus VP4 and shown it can induce membrane permeability in liposome model membranes. Dextran size-exclusion studies, chemical crosslinking and electron microscopy demonstrated that VP4 forms a multimeric membrane pore, with a channel size consistent with transfer of the single-stranded RNA genome. The membrane permeability induced by recombinant VP4 was influenced by pH and was comparable to permeability induced by infectious virions. These findings present a molecular mechanism for the involvement of VP4 in cell entry and provide a model system which will facilitate exploration of VP4 as a novel antiviral target for the picornavirus family.

Aging time on the aluminum basic acetate gel and its influence on the membrane permeability

International Nuclear Information System (INIS)

Clar, C; Scian, A. N; Aglietti, E.F

2003-01-01

Alumina ceramic membranes are new materials with important applications in separation processes with low energy requirements, high selectivity and ability to work at high and low temperatures.The preparation of alumina ceramic membranes from hydrates or aluminum salts as precursors implies obtaining a system of controlled porosity with a suitable mechanical resistance as well as the densification of the material thanks to the stable phases remaining after the thermal treatment.The metal carboxylates are potential precursors for the deposition and the subsequent formation of oxides at low temperatures.Aluminum basic acetate gel was synthesised in this work from commercial pseudobohemite. The influence of the aging time on the composition, crystalline structure and transition temperatures of the phases on the carboxylate was studied by XRD and DTA-TG.From suspensions of this aged gel at different times alumina ceramic membranes were prepared by dipcoating on different α-Al 2 O 3 supports and the influence of aging on the permeability of those membranes face to N 2 was also studied. It was observed that this is a parameter to be considered as it determines the thickness, permeability and integrity of the membranes

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

Science.gov (United States)

Saito, Hiroaki; Shinoda, Wataru

2011-12-29

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

Permeability of PEGylated immunoarsonoliposomes through in vitro blood brain barrier-medulloblastoma co-culture models for brain tumor therapy.

Science.gov (United States)

Al-Shehri, Abdulghani; Favretto, Marco E; Ioannou, Panayiotis V; Romero, Ignacio A; Couraud, Pierre-Olivier; Weksler, Babette Barbash; Parker, Terry L; Kallinteri, Paraskevi

2015-03-01

Owing to restricted access of pharmacological agents into the brain due to blood brain barrier (BBB) there is a need: 1. to develop a more representative 3-D-co-culture model of tumor-BBB interaction to investigate drug and nanoparticle transport into the brain for diagnostic and therapeutic evaluation. 2. to address the lack of new alternative methods to animal testing according to replacement-reduction-refinement principles. In this work, in vitro BBB-medulloblastoma 3-D-co-culture models were established using immortalized human primary brain endothelial cells (hCMEC/D3). hCMEC/D3 cells were cultured in presence and in absence of two human medulloblastoma cell lines on Transwell membranes. In vitro models were characterized for BBB formation, zonula occludens-1 expression and permeability to dextran. Transferrin receptors (Tfr) expressed on hCMEC/D3 were exploited to facilitate arsonoliposome (ARL) permeability through the BBB to the tumor by covalently attaching an antibody specific to human Tfr. The effect of anticancer ARLs on hCMEC/D3 was assessed. In vitro BBB and BBB-tumor co-culture models were established successfully. BBB permeability was affected by the presence of tumor aggregates as suggested by increased permeability of ARLs. There was a 6-fold and 8-fold increase in anti-Tfr-ARL uptake into VC312R and BBB-DAOY co-culture models, respectively, compared to plain ARLs. The three-dimensional models might be appropriate models to study the transport of various drugs and nanocarriers (liposomes and immunoarsonoliposomes) through the healthy and diseased BBB. The immunoarsonoliposomes can be potentially used as anticancer agents due to good tolerance of the in vitro BBB model to their toxic effect.

Prediction of Placental Barrier Permeability: A Model Based on Partial Least Squares Variable Selection Procedure

Directory of Open Access Journals (Sweden)

Yong-Hong Zhang

2015-05-01

Full Text Available Assessing the human placental barrier permeability of drugs is very important to guarantee drug safety during pregnancy. Quantitative structure–activity relationship (QSAR method was used as an effective assessing tool for the placental transfer study of drugs, while in vitro human placental perfusion is the most widely used method. In this study, the partial least squares (PLS variable selection and modeling procedure was used to pick out optimal descriptors from a pool of 620 descriptors of 65 compounds and to simultaneously develop a QSAR model between the descriptors and the placental barrier permeability expressed by the clearance indices (CI. The model was subjected to internal validation by cross-validation and y-randomization and to external validation by predicting CI values of 19 compounds. It was shown that the model developed is robust and has a good predictive potential (r2 = 0.9064, RMSE = 0.09, q2 = 0.7323, rp2 = 0.7656, RMSP = 0.14. The mechanistic interpretation of the final model was given by the high variable importance in projection values of descriptors. Using PLS procedure, we can rapidly and effectively select optimal descriptors and thus construct a model with good stability and predictability. This analysis can provide an effective tool for the high-throughput screening of the placental barrier permeability of drugs.

Long-term Performance of Permeable Reactive Barriers Using Zero-valent Iron: An Evaluation at Two Sites

National Research Council Canada - National Science Library

Wilkin, Richard T; Puls, Robert W; Sewell, Guy W

2002-01-01

Research described in this research brief explores the geochemical and microbiological processes occurring within zero-valent iron treatment zones in permeable reactive barriers that may contribute...

Arabidopsis annexin1 mediates the radical-activated plasma membrane Ca²+- and K+-permeable conductance in root cells.

Science.gov (United States)

Laohavisit, Anuphon; Shang, Zhonglin; Rubio, Lourdes; Cuin, Tracey A; Véry, Anne-Aliénor; Wang, Aihua; Mortimer, Jennifer C; Macpherson, Neil; Coxon, Katy M; Battey, Nicholas H; Brownlee, Colin; Park, Ohkmae K; Sentenac, Hervé; Shabala, Sergey; Webb, Alex A R; Davies, Julia M

2012-04-01

Plant cell growth and stress signaling require Ca²⁺ influx through plasma membrane transport proteins that are regulated by reactive oxygen species. In root cell growth, adaptation to salinity stress, and stomatal closure, such proteins operate downstream of the plasma membrane NADPH oxidases that produce extracellular superoxide anion, a reactive oxygen species that is readily converted to extracellular hydrogen peroxide and hydroxyl radicals, OH•. In root cells, extracellular OH• activates a plasma membrane Ca²⁺-permeable conductance that permits Ca²⁺ influx. In Arabidopsis thaliana, distribution of this conductance resembles that of annexin1 (ANN1). Annexins are membrane binding proteins that can form Ca²⁺-permeable conductances in vitro. Here, the Arabidopsis loss-of-function mutant for annexin1 (Atann1) was found to lack the root hair and epidermal OH•-activated Ca²⁺- and K⁺-permeable conductance. This manifests in both impaired root cell growth and ability to elevate root cell cytosolic free Ca²⁺ in response to OH•. An OH•-activated Ca²⁺ conductance is reconstituted by recombinant ANN1 in planar lipid bilayers. ANN1 therefore presents as a novel Ca²⁺-permeable transporter providing a molecular link between reactive oxygen species and cytosolic Ca²⁺ in plants.

Phasic changes of blood-brain-barrier permeability in mice after non-uniform γ-irradiation

International Nuclear Information System (INIS)

Ushakov, I.B.

1986-01-01

Early changes of blood-brain barrier (BBB) permeability in mice after irradiation of head or body were studied. The experiments were carried out on male-mice F 1 (C57xCBA) with medium mass of 25.1±0.8 g, irradiated in 2.58 C/kg dose to head or body. Correlation between BBB permeability decrease and radiation disease clinical manifestation frequency is determined. In early periods after irradiation, minimum two phases of BBB permeability change were observed: increase (0-2 h) and decrease (2-6 h) of permeability. BBB changes were expressed in later periods (24-120 h) as well. BBB permeability progressively increased after irradiation of head. According to the author's suggestion, this phenomenon gives evidence of generalization of vessel permeability disturbance (primarily of brain vessels) which leads to complete BBB dysfunction and to the loss of this morphofunctional formation's ability to perform its protective function. When considering BBB permeability connection with the frequency of neurologycal sign (tremor, ataxia) appearance, reversible correlation between these indicators is marked, beginning with the first period. The presence connection of fluid redistribution between blood and internal brain medium (edema growth) with the development of clinical manifestations of CNS affection is suggested

Highly permeable polymeric membranes based on the incorporation of the functional water channel protein Aquaporin Z

Science.gov (United States)

Kumar, Manish; Grzelakowski, Mariusz; Zilles, Julie; Clark, Mark; Meier, Wolfgang

2007-01-01

The permeability and solute transport characteristics of amphiphilic triblock-polymer vesicles containing the bacterial water-channel protein Aquaporin Z (AqpZ) were investigated. The vesicles were made of a block copolymer with symmetric poly-(2-methyloxazoline)-poly-(dimethylsiloxane)-poly-(2-methyloxazoline) (PMOXA15-PDMS110-PMOXA15) repeat units. Light-scattering measurements on pure polymer vesicles subject to an outwardly directed salt gradient in a stopped-flow apparatus indicated that the polymer vesicles were highly impermeable. However, a large enhancement in water productivity (permeability per unit driving force) of up to ≈800 times that of pure polymer was observed when AqpZ was incorporated. The activation energy (Ea) of water transport for the protein-polymer vesicles (3.4 kcal/mol) corresponded to that reported for water-channel-mediated water transport in lipid membranes. The solute reflection coefficients of glucose, glycerol, salt, and urea were also calculated, and indicated that these solutes are completely rejected. The productivity of AqpZ-incorporated polymer membranes was at least an order of magnitude larger than values for existing salt-rejecting polymeric membranes. The approach followed here may lead to more productive and sustainable water treatment membranes, whereas the variable levels of permeability obtained with different concentrations of AqpZ may provide a key property for drug delivery applications. PMID:18077364

Dynamic /sup 99m/Tc-DTPA radioaerosol lung scanning for the evaluation of alveolar-capillary barrier permeability

Energy Technology Data Exchange (ETDEWEB)

Maini, C L; Marchetti, L; Bonetti, M G; Giordano, A; Pistelli, R; Antonelli Incalzi, R

1987-01-01

Pulmonary clearance of small droplet /sup 99m/Tc-DTPA radioaerosol was studied in 100 patients (12 normal subjects, N; 10 asymptomatic healthy smoker, FA; 31 patients with interstitial lung diseases, IP; 47 patients with chronic obstructive lung disease, BPCO). The first seven minutes of clearance were described with the function At=Ao*exp(-K*t) and the time constant K was considered representative of the /sup 99m/Tc-DTPA clearance rate and hence of the alveolar-capillary barrier permeability. Groups FA, IP and BPCO showed a significant (p<0.05) or a highly significant (p<0.01) increase in permeability when compared to group N. No correlation was found between permeability and bronchial obstraction tests. The following conclusions were drawn: 1) /sup 99m/Tc-DTPA dynamic lung scanning is an easy, non-invasive method to assess derangements of alveolar-capillary barrier permeability secondary to epithelial damage; 2) permeability increase is a very early effect of cigarette smoke damafe to the epithelium; 3) other mechanisms of epithelial injury are present in diffuse lung disease; 4) while the clinical role of this new pathophysiological test is not yet clear, it is likely that it may become a very early marker of pulmonary epithelial damage in diffuse lung disease. 35 refs.

In vitro and in vivo activation of mitochondrial membrane permeability transition pore using triiodothyronine.

Science.gov (United States)

Endlicher, R; Drahota, Z; Červinková, Z

2016-06-20

Using a novel method for evaluating mitochondrial swelling (Drahota et al. 2012a) we studied the effect of calcium (Ca(2+)), phosphate (P(i)), and triiodothyronine (T(3)) on the opening of mitochondrial membrane permeability transition pore and how they interact in the activation of swelling process. We found that 0.1 mM P(i), 50 microM Ca(2+) and 25 microM T(3) when added separately increase the swelling rate to about 10 % of maximal values when all three factors are applied simultaneously. Our findings document that under experimental conditions in which Ca(2+) and P(i) are used as activating factors, the addition of T(3) doubled the rate of swelling. T(3) has also an activating effect on mitochondrial membrane potential. The T(3) activating effect was also found after in vivo application of T(3). Our data thus demonstrate that T(3) has an important role in opening the mitochondrial membrane permeability pore and activates the function of the two key physiological swelling inducers, calcium and phosphate ions.

Magnetic resonance imaging-guided focused ultrasound to increase localized blood-spinal cord barrier permeability.

Science.gov (United States)

Payne, Allison H; Hawryluk, Gregory W; Anzai, Yoshimi; Odéen, Henrik; Ostlie, Megan A; Reichert, Ethan C; Stump, Amanda J; Minoshima, Satoshi; Cross, Donna J

2017-12-01

Spinal cord injury (SCI) affects thousands of people every year in the USA, and most patients are left with some permanent paralysis. Therapeutic options are limited and only modestly affect outcome. To address this issue, we used magnetic resonance imaging-guided focused ultrasound (MRgFUS) as a non-invasive approach to increase permeability in the blood-spinal cord barrier (BSCB). We hypothesize that localized, controlled sonoporation of the BSCB by MRgFUS will aid delivery of therapeutics to the injury. Here, we report our preliminary findings for the ability of MRgFUS to increase BSCB permeability in the thoracic spinal cord of a normal rat model. First, an excised portion of normal rat spinal column was used to characterize the acoustic field and to estimate the insertion losses that could be expected in an MRgFUS blood spinal cord barrier opening. Then, in normal rats, MRgFUS was applied in combination with intravenously administered microbubbles to the spinal cord region. Permeability of the BSCB was indicated as signal enhancement by contrast administered prior to T1-weighted magnetic resonance imaging and verified by Evans blue dye. Neurological testing using the Basso, Beattie, and Breshnahan scale and the ladder walk was normal in 8 of 10 rats tested. Two rats showed minor impairment indicating need for further refinement of parameters. No gross tissue damage was evident by histology. In this study, we have opened successfully the blood spinal cord barrier in the thoracic region of the normal rat spine using magnetic resonance-guided focused ultrasound combined with microbubbles.

CMHC research project: Testing of air barriers construction details: Report

Energy Technology Data Exchange (ETDEWEB)

1991-01-01

This project was conducted to quantify the air leakage characteristics of the header joist, the electric outlets, and the window openings in wood-frame walls. The study evaluated the sealed internal membrane method, where polyethylene sheet and sealant provide the air barrier; the external air barrier method, which uses a continuous vapour permeable membrane (spun-bonded olefin film), sandwiched between two layers of external wall sheathing; and the airtight drywall method, where the interior gypsum board finish, together with framing materials and gaskets, are used as the air barrier. In addition, the traditional approach to wood-frame wall construction, where no special attention is given to achieving a continuous air barrier, was evaluated for comparison.

Enhanced permeability, selectivity, and antifouling ability of CNTs/Al2O3 membrane under electrochemical assistance.

Science.gov (United States)

Fan, Xinfei; Zhao, Huimin; Liu, Yanming; Quan, Xie; Yu, Hongtao; Chen, Shuo

2015-02-17

Membrane filtration provides effective solutions for removing contaminants, but achieving high permeability, good selectivity, and antifouling ability remains a great challenge for existing membrane filtration technologies. In this work, membrane filtration coupled with electrochemistry has been developed to enhance the filtration performance of a CNTs/Al2O3 membrane. The as-prepared CNTs/Al2O3 membrane, obtained by coating interconnected CNTs on an Al2O3 substrate, presented good pore-size tunability, mechanical stability, and electroconductivity. For the removal of a target (silica spheres as a probe) with a size comparable to the membrane pore size, the removal efficiency and flux at +1.5 V were 1.1 and 1.5 times higher, respectively, than those without electrochemical assistance. Moreover, the membrane also exhibited a greatly enhanced removal efficiency for contaminants smaller than the membrane pores, providing enhancements of 4 orders of magnitude and a factor of 5.7 for latex particles and phenol, respectively. These results indicated that both the permeability and the selectivity of CNTs/Al2O3 membranes can be significantly improved by electrochemical assistance, which was further confirmed by the removal of natural organic matter (NOM). The permeate flux and NOM removal efficiency at +1.5 V were about 1.6 and 3.0 times higher, respectively, than those without electrochemical assistance. In addition, the lost flux of the fouled membrane was almost completely recovered by an electrochemically assisted backwashing process.

Permeability of a Fluid Lipid Bilayer to Short-Chain Alcohols from First Principles.

Science.gov (United States)

Comer, Jeffrey; Schulten, Klaus; Chipot, Christophe

2017-06-13

Computational prediction of membrane permeability to small molecules requires accurate description of both the thermodynamics and kinetics underlying translocation across the lipid bilayer. In this contribution, well-converged, microsecond-long free-energy calculations are combined with a recently developed subdiffusive kinetics framework to describe the membrane permeation of a homologous series of short-tail alcohols, from methanol to 1-butanol, with unprecedented fidelity to the underlying molecular models. While the free-energy profiles exhibit barriers for passage through the center of the bilayer in all cases, the height of these barriers decreases with the length of the aliphatic chain of the alcohol, in quantitative agreement with experimentally determined differential solvation free energies in water and oil. A unique aspect of the subdiffusive model employed herein, which was developed in a previous article, is the determination of a position-dependent fractional order which quantifies the degree to which the motion of the alcohol deviates from classical diffusion along the thickness of the membrane. In the aqueous medium far from the bilayer, this quantity approaches 1.0, the asymptotic limit for purely classical diffusion, whereas it dips below 0.75 near the center of the membrane irrespective of the permeant. Remarkably, the fractional diffusivity near the center of membrane, where its influence on the permeability is the greatest, is similar among the four permeants despite the large difference in molecular weight and lipophilicity between methanol and 1-butanol. The relative permeabilities, which are estimated from the free-energy and fractional diffusivity profiles, are therefore determined predominantly by differences in the former rather than the latter. The predicted relative permeabilities are highly correlated with existing experimental results, albeit they do not agree quantitatively with them. On the other hand, quite unexpectedly, the

Acylation of salmon calcitonin modulates in vitro intestinal peptide flux through membrane permeability enhancement

DEFF Research Database (Denmark)

Trier, Sofie; Linderoth, Lars; Bjerregaard, Simon

2015-01-01

hypothesize that tailoring the acylation may be used to optimize intestinal translocation. This work aims to characterize acylated analogues of the therapeutic peptide salmon calcitonin (sCT), which lowers blood calcium, by systematically increasing acyl chain length at two positions, in order to elucidate...... to be optimal, as elongating the chain causes greater binding to the cell membrane but similar permeability, and we speculate that increasing the chain length further may decrease the permeability. In conclusion, acylated sCT acts as its own in vitro intestinal permeation enhancer, with reversible effects...... on Caco-2 cells, indicating that acylation of sCT may represent a promising tool to increase intestinal permeability without adding oral permeation enhancers....

Discontinuous permeable adsorptive barrier design and cost analysis: a methodological approach to optimisation.

Science.gov (United States)

Santonastaso, Giovanni Francesco; Bortone, Immacolata; Chianese, Simeone; Di Nardo, Armando; Di Natale, Michele; Erto, Alessandro; Karatza, Despina; Musmarra, Dino

2017-09-19

The following paper presents a method to optimise a discontinuous permeable adsorptive barrier (PAB-D). This method is based on the comparison of different PAB-D configurations obtained by changing some of the main PAB-D design parameters. In particular, the well diameters, the distance between two consecutive passive wells and the distance between two consecutive well lines were varied, and a cost analysis for each configuration was carried out in order to define the best performing and most cost-effective PAB-D configuration. As a case study, a benzene-contaminated aquifer located in an urban area in the north of Naples (Italy) was considered. The PAB-D configuration with a well diameter of 0.8 m resulted the best optimised layout in terms of performance and cost-effectiveness. Moreover, in order to identify the best configuration for the remediation of the aquifer studied, a comparison with a continuous permeable adsorptive barrier (PAB-C) was added. In particular, this showed a 40% reduction of the total remediation costs by using the optimised PAB-D.

Water and vapor permeability at different temperatures of poly (3-Hydroxybutyrate dense membranes

Directory of Open Access Journals (Sweden)

Luiz H. Poley

2005-03-01

Full Text Available Polyhydroxyalkanoates (PHAs are polymers produced from renewable resources with biodegradability and biocompatibility, being therefore attractive for medical and pharmaceutical purposes. Poly (3-hydroxybutyrate (PHB is the most important polymer of this family by considering the biotechnology process of its synthesis. In the present study, dense films of PHB were prepared by casting from chloroform solutions (1% m/m. Permeability studies with water, methanol, ethanol and n-propanol were performed using the gravimetric method at different temperatures (from 50 ºC to 65 ºC. Results provide new data on permeability coefficients of PHB membranes.

Decreased outer membrane permeability in imipenem-resistant mutants of Pseudomonas aeruginosa.

OpenAIRE

Trias, J; Dufresne, J; Levesque, R C; Nikaido, H

1989-01-01

The outer membrane of imipenem-resistant mutants of Pseudomonas aeruginosa was shown to have decreased permeability to imipenem but not to cephaloridine. These experiments were performed with intact cells and liposomes containing imipenem-hydrolyzing beta-lactamase derived from Pseudomonas maltophilia, in both cases utilizing an imipenem concentration of 50 microM. In contrast, liposome swelling assays using imipenem at 8 mM detected no significant difference between the imipenem-resistant mu...

Recovery of ammonia from swine manure using gas-permeable membranes: Effect of aeration

Science.gov (United States)

Gas-permeable membranes can recover ammonia from manure, reducing pollution whilst converting ammonia into ammonium salt fertilizer. The process involves manure pH control to increase ammonium (NH4) recovery rate that is normally carried out using an alkali. In this study a new strategy to avoid the...

Automated Impedance Tomography for Monitoring Permeable Reactive Barrier Health

Energy Technology Data Exchange (ETDEWEB)

LaBrecque, D J; Adkins, P L

2009-07-02

The objective of this research was the development of an autonomous, automated electrical geophysical monitoring system which allows for near real-time assessment of Permeable Reactive Barrier (PRB) health and aging and which provides this assessment through a web-based interface to site operators, owners and regulatory agencies. Field studies were performed at four existing PRB sites; (1) a uranium tailing site near Monticello, Utah, (2) the DOE complex at Kansas City, Missouri, (3) the Denver Federal Center in Denver, Colorado and (4) the Asarco Smelter site in East Helena, Montana. Preliminary surface data over the PRB sites were collected (in December, 2005). After the initial round of data collection, the plan was modified to include studies inside the barriers in order to better understand barrier aging processes. In September 2006 an autonomous data collection system was designed and installed at the EPA PRB and the electrode setups in the barrier were revised and three new vertical electrode arrays were placed in dedicated boreholes which were in direct contact with the PRB material. Final data were collected at the Kansas City, Denver and Monticello, Utah PRB sites in the fall of 2007. At the Asarco Smelter site in East Helena, Montana, nearly continuous data was collected by the autonomous monitoring system from June 2006 to November 2007. This data provided us with a picture of the evolution of the barrier, enabling us to examine barrier changes more precisely and determine whether these changes are due to installation issues or are normal barrier aging. Two rounds of laboratory experiments were carried out during the project. We conducted column experiments to investigate the effect of mineralogy on the electrical signatures resulting from iron corrosion and mineral precipitation in zero valent iron (ZVI) columns. In the second round of laboratory experiments we observed the electrical response from simulation of actual field PRBs at two sites: the

Dynamic 99mTc-DTPA radioaerosol lung scanning for the evaluation of alveolar-capillary barrier permeability

International Nuclear Information System (INIS)

Maini, C.L.; Marchetti, L.; Bonetti, M.G.; Giordano, A.; Pistelli, R.; Antonelli Incalzi, R.

1987-01-01

Pulmonary clearance of small droplet 99m Tc-DTPA radioaerosol was studied in 100 patients (12 normal subjects, N; 10 asymptomatic healthy smoker, FA; 31 patients with interstitial lung diseases, IP; 47 patients with chronic obstructive lung disease, BPCO). The first seven minutes of clearance were described with the function At=Ao*exp(-K*t) and the time constant K was considered representative of the 99m Tc-DTPA clearance rate and hence of the alveolar-capillary barrier permeability. Groups FA, IP and BPCO showed a significant (p 99m Tc-DTPA dynamic lung scanning is an easy, non-invasive method to assess derangements of alveolar-capillary barrier permeability secondary to epithelial damage; 2) permeability increase is a very early effect of cigarette smoke damafe to the epithelium; 3) other mechanisms of epithelial injury are present in diffuse lung disease; 4) while the clinical role of this new pathophysiological test is not yet clear, it is likely that it may become a very early marker of pulmonary epithelial damage in diffuse lung disease

Bifidobacterium animalis ssp. lactis CNCM-I2494 Restores Gut Barrier Permeability in Chronically Low-Grade Inflamed Mice.

Science.gov (United States)

Martín, Rebeca; Laval, Laure; Chain, Florian; Miquel, Sylvie; Natividad, Jane; Cherbuy, Claire; Sokol, Harry; Verdu, Elena F; van Hylckama Vlieg, Johan; Bermudez-Humaran, Luis G; Smokvina, Tamara; Langella, Philippe

2016-01-01

Growing evidence supports the efficacy of many probiotic strains in the management of gastrointestinal disorders associated with deregulated intestinal barrier function and/or structure. In particular, bifidobacteria have been studied for their efficacy to both prevent and treat a broad spectrum of animal and/or human gut disorders. The aim of the current work was thus to evaluate effects on intestinal barrier function of Bifidobacterium animalis ssp. lactis CNCM-I2494, a strain used in fermented dairy products. A chronic dinitrobenzene sulfonic acid (DNBS)-induced low-grade inflammation model causing gut dysfunction in mice was used in order to study markers of inflammation, intestinal permeability, and immune function in the presence of the bacterial strain. In this chronic low-grade inflammation mice model several parameters pointed out the absence of an over active inflammation process. However, gut permeability, lymphocyte populations, and colonic cytokines were found to be altered. B. animalis ssp. lactis CNCM-I2494 was able to protect barrier functions by restoring intestinal permeability, colonic goblet cell populations, and cytokine levels. Furthermore, tight junction (TJ) proteins levels were also measured by qRT-PCR showing the ability of this strain to specifically normalize the level of several TJ proteins, in particular for claudin-4. Finally, B. lactis strain counterbalanced CD4(+) lymphocyte alterations in both spleen and mesenteric lymphoid nodes. It restores the Th1/Th2 ratio altered by the DNBS challenge (which locally augments CD4(+) Th1 cells) by increasing the Th2 response as measured by the increase in the production of major representative Th2 cytokines (IL-4, IL-5, and IL-10). Altogether, these data suggest that B. animalis ssp. lactis CNCM-I2494 may efficiently prevent disorders associated with increased barrier permeability.

Safety, efficacy, and molecular mechanism of claudin-1-specific peptides to enhance blood-nerve-barrier permeability.

Science.gov (United States)

Sauer, Reine-Solange; Krug, Susanne M; Hackel, Dagmar; Staat, Christian; Konasin, Natalia; Yang, Shaobing; Niedermirtl, Benedikt; Bosten, Judith; Günther, Ramona; Dabrowski, Sebastian; Doppler, Kathrin; Sommer, Claudia; Blasig, Ingolf E; Brack, Alexander; Rittner, Heike L

2014-07-10

The blood-nerve barrier consists of the perineurium and endoneurial vessels. The perineurial barrier is composed of a basal membrane and a layer of perineurial cells sealed by tight junction proteins preventing e.g. application of analgesics for selective regional pain control. One of the barrier-sealing proteins in the blood-nerve barrier is claudin-1. Therefore, the claudin-1-peptidomimetics (C1C2), derived from the first extracellular loop (ECL1) on claudin-1 was developed. In this study, we further evaluated the expression of tight junction proteins in the perineurium in Wistar rats and characterized the specificity, in vivo applicability, mechanism of action as well as the biocompatibility of C1C2. In the perineurium, claudin-19, tricellulin and ZO-1, but no claudin-2, 3, 8 and -11 were expressed. C1C2 specifically bound to the ECL1 of claudin-1 and fluorescent 5,6-carboxytetramethylrhodamine-C1C2 was rapidly internalized. Opening the perineurium with C1C2 reduced the mRNA and protein expression of claudin-1 and increased small and macromolecule permeability into the peripheral nerve. Application of C1C2 facilitated regional analgesia using μ-opioid receptor agonists like DAMGO or morphine without motor impairment in naïve rats as well as rats with hind paw inflammation. In contrast the control peptide C2C2 derived from ECL1 on claudin-2 did neither open the barrier nor facilitated opioid-mediated regional analgesia. C1C2 delivery was well tolerated and caused no morphological and functional nerve damage. C1C2 effects could be reversed by interference with the wnt-signal-transduction pathway, specifically the homeobox transcription factor cdx2, using a glycogen-synthase-kinase-3 inhibitor. In summary, we describe the composition of and a pathway to open the perineurial barrier employing a peptide to deliver hydrophilic substances to the peripheral nerve. Copyright © 2014 Elsevier B.V. All rights reserved.

A permeability barrier surrounds taste buds in lingual epithelia

Science.gov (United States)

Dando, Robin; Pereira, Elizabeth; Kurian, Mani; Barro-Soria, Rene; Chaudhari, Nirupa

2014-01-01

Epithelial tissues are characterized by specialized cell-cell junctions, typically localized to the apical regions of cells. These junctions are formed by interacting membrane proteins and by cytoskeletal and extracellular matrix components. Within the lingual epithelium, tight junctions join the apical tips of the gustatory sensory cells in taste buds. These junctions constitute a selective barrier that limits penetration of chemosensory stimuli into taste buds (Michlig et al. J Comp Neurol 502: 1003–1011, 2007). We tested the ability of chemical compounds to permeate into sensory end organs in the lingual epithelium. Our findings reveal a robust barrier that surrounds the entire body of taste buds, not limited to the apical tight junctions. This barrier prevents penetration of many, but not all, compounds, whether they are applied topically, injected into the parenchyma of the tongue, or circulating in the blood supply, into taste buds. Enzymatic treatments indicate that this barrier likely includes glycosaminoglycans, as it was disrupted by chondroitinase but, less effectively, by proteases. The barrier surrounding taste buds could also be disrupted by brief treatment of lingual tissue samples with DMSO. Brief exposure of lingual slices to DMSO did not affect the ability of taste buds within the slice to respond to chemical stimulation. The existence of a highly impermeable barrier surrounding taste buds and methods to break through this barrier may be relevant to basic research and to clinical treatments of taste. PMID:25209263

A permeability barrier surrounds taste buds in lingual epithelia.

Science.gov (United States)

Dando, Robin; Pereira, Elizabeth; Kurian, Mani; Barro-Soria, Rene; Chaudhari, Nirupa; Roper, Stephen D

2015-01-01

Epithelial tissues are characterized by specialized cell-cell junctions, typically localized to the apical regions of cells. These junctions are formed by interacting membrane proteins and by cytoskeletal and extracellular matrix components. Within the lingual epithelium, tight junctions join the apical tips of the gustatory sensory cells in taste buds. These junctions constitute a selective barrier that limits penetration of chemosensory stimuli into taste buds (Michlig et al. J Comp Neurol 502: 1003-1011, 2007). We tested the ability of chemical compounds to permeate into sensory end organs in the lingual epithelium. Our findings reveal a robust barrier that surrounds the entire body of taste buds, not limited to the apical tight junctions. This barrier prevents penetration of many, but not all, compounds, whether they are applied topically, injected into the parenchyma of the tongue, or circulating in the blood supply, into taste buds. Enzymatic treatments indicate that this barrier likely includes glycosaminoglycans, as it was disrupted by chondroitinase but, less effectively, by proteases. The barrier surrounding taste buds could also be disrupted by brief treatment of lingual tissue samples with DMSO. Brief exposure of lingual slices to DMSO did not affect the ability of taste buds within the slice to respond to chemical stimulation. The existence of a highly impermeable barrier surrounding taste buds and methods to break through this barrier may be relevant to basic research and to clinical treatments of taste. Copyright © 2015 the American Physiological Society.

Involvement of membrane lipids in radiation damage to potassium-ion permeability of Escherichia coli

Energy Technology Data Exchange (ETDEWEB)

Suzuki, S [Tokyo Univ. (Japan). Inst. for Medical Science; Akamatsu, Y

1978-02-01

Radiation damage to K/sup +/ permeability of an unsaturated fatty acid auxotroph of E.coli grown with oleate or linolenate was investigated at different temperatures. A remarkable effect of radiation was observed at 0/sup 0/C with cells that had been grown in linolenate at 42/sup 0/C. This indicates that, besides protein, membrane lipids at least are involved in the radiation damage. The damage also seems to be affected by the fluidity of membrane lipids.

A study on H{sub 2}S permeability of CsHSO{sub 4} membranes

Energy Technology Data Exchange (ETDEWEB)

Mbah, Jonathan; Wolan, John T. [Department of Chemical and Biomedical Engineering, College of Engineering, University of South Florida, Tampa, FL 33620 (United States); Clean Energy Research Center, College of Engineering, University of South Florida, Tampa, FL 33617 (United States); Krakow, Burton [Clean Energy Research Center, College of Engineering, University of South Florida, Tampa, FL 33617 (United States); Stefanakos, Elias [Clean Energy Research Center, College of Engineering, University of South Florida, Tampa, FL 33617 (United States); Department of Electrical Engineering, College of Engineering, University of South Florida, Tampa, FL 33617 (United States)

2009-03-15

The gas permeability of H{sub 2}S gas at 150 C through ultra-thin cesium hydrogen sulfate (CsHSO{sub 4}) membranes has been investigated. Gas chromatography-mass spectrometry analyses indicate that CsHSO{sub 4} membrane is impermeable to H{sub 2}S gas under test conditions. The apparent micropore diameter of the membrane averaged between 9.5 and 11.5 Aa with a maximum permeance of 0.09 Barrer (6.75 x 10{sup -19} m{sup 2} s{sup -1} Pa{sup -1}). Atomic force microscope and X-ray diffraction analyses show respectively that the surface morphology and crystal structure of the membranes are preserved, with no adverse effect from prolonged exposure to H{sub 2}S gas. Electrochemical impedance spectroscopy analysis confirm over a 30% decrease in membrane resistance via an 80% reduction in membrane thickness. (author)

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

Accurate determination of blood–brain barrier permeability using dynamic contrast-enhanced T1-weighted MRI

DEFF Research Database (Denmark)

Cramer, Stig P; Larsson, Henrik B W

2014-01-01

Dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) is increasingly used to estimate permeability in situations with subtle blood-brain barrier (BBB) leakage. However, the method's ability to differentiate such low values from zero is unknown, and no consensus exists on optimal selection...

Blood-brain barrier permeability and monocyte infiltration in experimental allergic encephalomyelitis : a quantitative MRI study

NARCIS (Netherlands)

Floris, S.; Blezer, E.L.A.; Schreibelt, Gerty; Dopp, E.; Pol, van der S.M.A.; Schadee-Eestermans, I.L.; Nicolaij, K.; Dijkstra, C.D.; Vries, de H.E.

2004-01-01

Enhanced cerebrovascular permeability and cellular infiltration mark the onset of early multiple sclerosis lesions. So far, the precise sequence of these events and their role in lesion formation and disease progression remain unknown. Here we provide quantitative evidence that blood–brain barrier

LONG-TERM GEOCHEMICAL BEHAVIOR OF A ZEROVALENT IRON PERMEABLE REACTIVE BARRIER FOR THE TREATMENT OF HEXAVALENT CHROMIUM IN GROUNDWATER

Science.gov (United States)

Passive, in-situ reactive barriers have proven to be viable, cost-effective systems for the remediation of Cr-contaminated groundwater at some sites. Permeable reactive barriers (PRBs) are installed in the flow-path of groundwater, most typically as vertical treatment walls. Re...

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;

Diffusion studies on permeable nitroxyl spin probes through bilayer lipid membranes: A low frequency ESR study

International Nuclear Information System (INIS)

Meenakumari, V.; Benial, A. Milton Franklin; Utsumi, Hideo; Ichikawa, Kazuhiro; Yamada, Ken-ichi; Hyodo, Fuminori; Jawahar, A.

2015-01-01

Electron spin resonance (ESR) studies were carried out for permeable 2mM 14 N-labeled deutrated 3 Methoxy carbonyl-2,2,5,5-tetramethyl-pyrrolidine-1-oxyl (MC-PROXYL) in pure water and 1mM, 2mM, 3mM, 4mM concentration of 14N-labeled deutrated MC-PROXYL in 400mM concentration of liposomal solution by using a 300 MHz ESR spectrometer. The ESR parameters such as linewidth, hyperfine coupling constant, g-factor, partition parameter and permeability were reported for these samples. The line broadening was observed for the nitroxyl spin probe in the liposomal solution. The line broadening indicates that the high viscous nature of the liposomal solution. The partition parameter and permeability values indicate the maximum diffusion of nitroxyl spin probes in the bilayer lipid membranes at 2 mM concentration of nitroxyl radical. This study illustrates that ESR can be used to differentiate between the intra and extra- membrane water by loading the liposome vesicles with a lipid-permeable nitroxyl spin probe. From the ESR results, the spin probe concentration was optimized as 2mM in liposomal solution for ESR phantom studies/imaging, invivo and invitro experiments

Hydrogen-permeable TiO{sub 2}/SiO{sub 2} membranes formed by chemical vapor deposition

Energy Technology Data Exchange (ETDEWEB)

Ha, Heung Yong; Nam, Suk Woo; Yoon, Sung Pil [Korea Institute of Science and Technology, Seoul (Korea, Republic of)] [and others

1994-12-31

Thin films of TiO{sub 2}/SiO{sub 2} were deposited on the inner surface of the porous support tubes by the decomposition of tetraisopropyl titanate (TIPT) and tetraethyl orthosilicate (TEOS) at atmospheric pressure. Dense and hydrogen-permeable membranes were formed at 400-600{degrees}C. The permeation rate of H{sub 2} through the membrane at 600{degrees}C was about 0.3 cm{sup 3}(STP)/min-cm{sup 2}-atm and H{sub 2}/N{sub 2} permeation ratio was above 1000. The permeation properties of the membranes were investigated at various deposition temperatures and TIPT/TEOS concentrations. Decomposition of TIPT alone at temperatures above 400{degrees}C produced porous crystalline TiO{sub 2} films which were not H{sub 2}-selective. Decomposition of TEOS, however produced H{sub 2}-permeable SiO{sub 2} films at 400-600{degrees}C but film deposition rate was very low. Addition of TIPT to the TEOS stream significantly accelerated the deposition rate and produced highly H{sub 2}-selective films. Increasing the TEPT/TEOS ratios increased the deposition rate. The TiO{sub 2}/SiO{sub 2} membranes have the permeation properties comparable to those of SiO{sub 2} membranes. The TiO{sub 2}/SiO{sub 2} membranes were stable and did not show significant densification during the treatment at high temperature.

Integrin-Linked Kinase Is Indispensable for Keratinocyte Differentiation and Epidermal Barrier Function.

Science.gov (United States)

Sayedyahossein, Samar; Rudkouskaya, Alena; Leclerc, Valerie; Dagnino, Lina

2016-02-01

A functional permeability barrier is essential to prevent the passage of water and electrolytes, macromolecules, and pathogens through the epidermis. This is accomplished in terminally differentiated keratinocytes through formation of a cornified envelope and the assembly of tight intercellular junctions. Integrin-linked kinase (ILK) is a scaffold protein essential for hair follicle morphogenesis and epidermal attachment to the basement membrane. However, the biological functions of ILK in differentiated keratinocytes remain poorly understood. Furthermore, whether ILK is implicated in keratinocyte differentiation and intercellular junction formation has remained an unresolved issue. Here we describe a pivotal role for ILK in keratinocyte differentiation responses to increased extracellular Ca(2+), regulation of adherens and tight junction assembly, and the formation of an outside-in permeability barrier toward macromolecules. In the absence of ILK, the calcium sensing receptor, E-cadherin, and ZO-1 fail to translocate to the cell membrane, through mechanisms that involve abnormalities in microtubules and in RhoA activation. In situ, ILK-deficient epidermis exhibits reduced tight junction formation and increased outside-in permeability to a dextran tracer, indicating reduced barrier properties toward macromolecules. Therefore, ILK is an essential component of keratinocyte differentiation programs that contribute to epidermal integrity and the establishment of its barrier properties. Copyright © 2015 The Authors. Published by Elsevier Inc. All rights reserved.

Gas permeability of bentonite barriers: development, construction and testing of a measurement system

Directory of Open Access Journals (Sweden)

Heraldo Nunes Pitanga

Full Text Available Abstract This article proposes a testing device to quickly and reliably estimate the gas permeability of bentonite-based clay barriers used in landfill cover systems. The testing methodology is based on a transient gas flow regime that passes through the barrier, therefore not requiring the use of sophisticated equipment that aim to maintain constant differential pressure and measure the gas flow, common requirements for testing methods under a permanent flow regime. To confirm the feasibility of the proposed technique, tests were performed on a pure hydrated bentonite layer, which subsequently encompassed samples of geosynthetic clay liner (GCL at different moisture contents. Geosynthetic clay liners are often selected as a part of the barrier layer for cover systems in solid waste landfills to prevent infiltration of rainfall and migration of biogas into the atmosphere. The results confirmed the equipment reliability and differentiate the different responses of the gas flow barriers studied, considering their different compositions and different moistures.

Enhanced Proton Conductivity and Methanol Permeability Reduction via Sodium Alginate Electrolyte-Sulfonated Graphene Oxide Bio-membrane

Science.gov (United States)

Shaari, N.; Kamarudin, S. K.; Basri, S.; Shyuan, L. K.; Masdar, M. S.; Nordin, D.

2018-03-01

The high methanol crossover and high cost of Nafion® membrane are the major challenges for direct methanol fuel cell application. With the aim of solving these problems, a non-Nafion polymer electrolyte membrane with low methanol permeability and high proton conductivity based on the sodium alginate (SA) polymer as the matrix and sulfonated graphene oxide (SGO) as an inorganic filler (0.02-0.2 wt%) was prepared by a simple solution casting technique. The strong electrostatic attraction between -SO3H of SGO and the sodium alginate polymer increased the mechanical stability, optimized the water absorption and thus inhibited the methanol crossover in the membrane. The optimum properties and performances were presented by the SA/SGO membrane with a loading of 0.2 wt% SGO, which gave a proton conductivity of 13.2 × 10-3 Scm-1, and the methanol permeability was 1.535 × 10-7 cm2 s-1 at 25 °C, far below that of Nafion (25.1 × 10-7 cm2 s-1) at 25 °C. The mechanical properties of the sodium alginate polymer in terms of tensile strength and elongation at break were improved by the addition of SGO.

Heavy metal uptake and leaching from polluted soil using permeable barrier in DTPA-assisted phytoextraction.

Science.gov (United States)

Zhao, Shulan; Shen, Zhiping; Duo, Lian

2015-04-01

Application of sewage sludge (SS) in agriculture is an alternative technique of disposing this waste. But unreasonable application of SS leads to excessive accumulation of heavy metals in soils. A column experiment was conducted to test the availability of heavy metals to Lolium perenne grown in SS-treated soils following diethylene triamine penta acetic acid (DTPA) application at rates of 0, 10 and 20 mmol kg(-1) soil. In order to prevent metal leaching in DTPA-assisted phytoextraction process, a horizontal permeable barrier was placed below the treated soil, and its effectiveness was also assessed. Results showed that DTPA addition significantly increased metal uptake by L. perenne shoots and metal leaching. Permeable barriers increased metal concentrations in plant shoots and effectively decreased metal leaching from the treated soil. Heavy metals in SS-treated soils could be gradually removed by harvesting L. perenne many times in 1 year and adding low dosage of DTPA days before each harvest.

Fifteen-year Assessment of a Permeable Reactive Barrier for Treatment of Chromate and Trichloroethylene in Groundwater

Science.gov (United States)

The fifteen-year performance of a granular iron, permeable reactive barrier (PRB; Elizabeth City, North Carolina) is reviewed with respect to contaminant treatment (hexavalent chromium and trichloroethylene) and hydraulic performance. Due to in-situ treatment of the chromium sou...

In vitro and in vivo activation of mitochondrial membrane permeability transition pore using triiodothyronine

Czech Academy of Sciences Publication Activity Database

Endlicher, R.; Drahota, Zdeněk; Červinková, Z.

2016-01-01

Roč. 65, č. 2 (2016), s. 321-331 ISSN 0862-8408 R&D Projects: GA ČR(CZ) GB14-36804G Institutional support: RVO:67985823 Keywords : rat liver mitochondria * membrane permeability transition pore * thyroid hormones Subject RIV: EB - Genetics ; Molecular Biology Impact factor: 1.461, year: 2016

Characterization of NaA Zeolite Oxygen Permeable Membrane on TiO2/α-Al2O3 Composite Support

Directory of Open Access Journals (Sweden)

Zhu Mengfu

2016-01-01

Full Text Available The NaA zeolite membrane was synthesized on the surface of TiO2/α-Al2O3 composite support with TiO2 as modifier of α-Al2O3 porous tubular ceramic membrane support by crystallization method. The structure characterization indicated that the TiO2 of the support surface could effectively improve the surface properties of the support. It didn’t affect the crystallization of NaA synthesis liquid and synthesis process of NaA zeolite membrane. There were no obvious defects between the crystal particles with size of approximate 6μm. The perfect and complete membrane with thickness of approximate 15μm combined closely with support to connection together by TiO2 modified. The oxygen permeability of the membrane on TiO2/α-Al2O3 composite support improves of 47% compared with that of α-Al2O3 support. So the process of TiO2 modifying the surface of α-Al2O3 support should increase the oxygen permeability of the NaA zeolite membrane.

Removal of chromate in a permeable reactive barrier using zero-valent iron

DEFF Research Database (Denmark)

Kjeldsen, Peter; Locht, T

2002-01-01

Chromate is a commonly found groundwater contaminant. Permeable reactive barriers containing zero-valent iron as iron filings are able to remove the chromate by a combined reduction/precipitation reaction. However, due to the passivation of the reduction capability of the iron surfaces by the pre......). Mixing in sand had no significant enhancing effect on the removal capacity, in contrast to a pH adjustment of the groundwater to pH 4, which significantly increased the removal capacity....

LOCALIZATION OF PERMEABILITY BARRIERS IN THE FROG SKIN EPITHELIUM

Science.gov (United States)

Martinez-Palomo, A.; Erlij, D.; Bracho, H.

1971-01-01

Ruthenium red and colloidal lanthanum were used to determine the site of the structural barriers to diffusion within the intercellular spaces of frog skin epithelium. Electron micrographs show that occluding zonules located at the outer border of the stratum corneum and at the outer layer of the stratum granulosum are true tight junctions since they are impermeable to these tracers. Measurement of 140La uptake by the living skin shows that lanthanum moves across the external surface of the skin readily, into and out of a compartment that has a limited capacity and is bounded on its internal side by a barrier impermeable to lanthanum. Examination of these skins with the electron microscope suggests that the compartment is localized between the external membrane of the cells at the outer layer of the s. granulosum and at the outermost surface of the skin. These observations and other findings described in the literature indicate that the site of the external high resistance barrier of the frog skin is localized at the outer border of the s. granulosum. PMID:4329611

Evaluation of blood--brain barrier permeability changes in rhesus monkeys and man using 82Rb and positron emission tomography

International Nuclear Information System (INIS)

Yen, C.K.; Budinger, T.F.

1981-01-01

Dynamic positron tomography of the brain with 82 Rb, obtained from a portable generator [ 82 Sr (25 days) -- 82 Rb (76 sec)], provides a means of studying blood-brain barrier (BBB) permeability in physiological and clinical investigations. The BBB in rhesus monkeys was opened unilaterally by intracarotid infusion of 3 M urea. This osmotic barrier opening allowed entry into the brain of intravenously administered rubidium chloride. The BBB opening was demonstrated noninvasively using 82 Rb and positron emission tomography and corroborated by the accumulation of 86 Rb in tissue samples. Positron emission tomography studies can be repeated every 5 min and indicate that dynamic tomography or static imaging can be used to study BBB permeability changes induced by a wide variety of noxious stimuli. Brain tumors in human subjects are readily detected because of the usual BBB permeability disruption in and around the tumors

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

Science.gov (United States)

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

2018-07-01

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

Mitochondrial Membrane Permeability Inhibitors in Acute Myocardial Infarction

Directory of Open Access Journals (Sweden)

Cory Trankle, MD

2016-10-01

Full Text Available Despite therapeutic advances, acute myocardial infarction (AMI remains a leading cause of morbidity and mortality worldwide. One potential limitation of the current treatment paradigm is the lack of effective therapies to optimize reperfusion after ischemia and prevent reperfusion-mediated injury. Experimental studies indicate that this process accounts for up to 50% of the final infarct size, lending it importance as a potential target for cardioprotection. However, multiple therapeutic approaches have shown potential in pre-clinical and early phase trials but a paucity of clear clinical benefit when expanded to larger studies. Here we explore this history of trials and errors of the studies of cyclosporine A and other mitochondrial membrane permeability inhibitors, agents that appeared to have a promising pre-clinical record yet provided disappointing results in phase III clinical trials.

Controlling the hydration of the skin though the application of occluding barrier creams.

Science.gov (United States)

Sparr, Emma; Millecamps, Danielle; Isoir, Muriel; Burnier, Véronique; Larsson, Åsa; Cabane, Bernard

2013-03-06

The skin is a barrier membrane that separates environments with profoundly different water contents. The barrier properties are assured by the outer layer of the skin, the stratum corneum (SC), which controls the transepidermal water loss. The SC acts as a responding membrane, since its hydration and permeability vary with the boundary condition, which is the activity of water at the outer surface of the skin. We show how this boundary condition can be changed by the application of a barrier cream that makes a film with a high resistance to the transport of water. We present a quantitative model that predicts hydration and water transport in SC that is covered by such a film. We also develop an experimental method for measuring the specific resistance to water transport of films made of occluding barrier creams. Finally, we combine the theoretical model with the measured properties of the barrier creams to predict how a film of cream changes the activity of water at the outer surface of the SC. Using the known variations of SC permeability and hydration with the water activity in its environment (i.e. the relative humidity), we can thus predict how a film of barrier cream changes SC hydration.

Polyhydroxybutyrate Targets Mammalian Mitochondria and Increases Permeability of Plasmalemmal and Mitochondrial Membranes

Science.gov (United States)

Elustondo, Pia A.; Angelova, Plamena R.; Kawalec, Michał; Michalak, Michał; Kurcok, Piotr; Abramov, Andrey Y.; Pavlov, Evgeny V.

2013-01-01

Poly(3-hydroxybutyrate) (PHB) is a polyester of 3-hydroxybutyric acid (HB) that is ubiquitously present in all organisms. In higher eukaryotes PHB is found in the length of 10 to 100 HB units and can be present in free form as well as in association with proteins and inorganic polyphosphate. It has been proposed that PHB can mediate ion transport across lipid bilayer membranes. We investigated the ability of PHB to interact with living cells and isolated mitochondria and the effects of these interactions on membrane ion transport. We performed experiments using a fluorescein derivative of PHB (fluo-PHB). We found that fluo-PHB preferentially accumulated inside the mitochondria of HeLa cells. Accumulation of fluo-PHB induced mitochondrial membrane depolarization. This membrane depolarization was significantly delayed by the inhibitor of the mitochondrial permeability transition pore - Cyclosporin A. Further experiments using intact cells as well as isolated mitochondria confirmed that the effects of PHB directly linked to its ability to facilitate ion transport, including calcium, across the membranes. We conclude that PHB demonstrates ionophoretic properties in biological membranes and this effect is most profound in mitochondria due to the selective accumulation of the polymer in this organelle. PMID:24086638

Aging and sex influence the permeability of the blood-brain barrier in the rat

International Nuclear Information System (INIS)

Saija, A.; Princi, P.; D'Amico, N.; De Pasquale, R.; Costa, G.

1990-01-01

The aim of the present study was to investigate the existence of aging- and sex-related alterations in the permeability of the blood-brain barrier (BBB) in the rat, by calculating a unidirectional blood-to-brain transfer constant (Ki) for the circulating tracer [ 14 C]-α-aminoisobutyric acid. The authors observed that: (a) the permeability of the BBB significantly increased within the frontal and temporo-parietal cortex, hypothalamus and cerebellum in 28-30 week old rats, in comparison with younger animals; (b) in several brain areas of female intact rats higher Ki values (even though not significantly different) were calculated at oestrus than at proestrus; (c) in 1-week ovariectomized rats there was a marked increase of Ki values at the level of the frontal, temporo-parietal and occipital cortex, cerebellum and brain-stem. One can speculate that aging and sex-related alterations in thee permeability of the BBB reflect respectively changes in brain neurochemical system activity and in plasma steroid hormone levels

Negotiation of intracellular membrane barriers by TAT-modified gold nanoparticles.

Science.gov (United States)

Krpetić, Zeljka; Saleemi, Samia; Prior, Ian A; Sée, Violaine; Qureshi, Rumana; Brust, Mathias

2011-06-28

This paper contributes to the debate on how nanosized objects negotiate membrane barriers inside biological cells. The uptake of peptide-modified gold nanoparticles by HeLa cells has been quantified using atomic emission spectroscopy. The TAT peptide from the HIV virus was singled out as a particularly effective promoter of cellular uptake. The evolution of the intracellular distribution of TAT-modified gold nanoparticles with time has been studied in detail by TEM and systematic image analysis. An unusual trend of particles disappearing from the cytosol and the nucleus and accumulating massively in vesicular bodies was observed. Subsequent release of the particles, both by membrane rupture and by direct transfer across the membrane boundary, was frequently found. Ultimately, near total clearing of particles from the cells occurred. This work provides support for the hypothesis that cell-penetrating peptides can enable small objects to negotiate membrane barriers also in the absence of dedicated transport mechanisms.

Autoradiographic study of the permeability characteristics of the small intestine

Energy Technology Data Exchange (ETDEWEB)

Kingham, J G.C.; Baker, J H; Loehry, C A [Royal Victoria Hospital, Bournemouth (UK)

1978-02-01

This autoradiographic study demonstrates the distribution of a range of small solutes and macromolecules in the mucosa of the guinea-pig small intestine after intracardiac injection. The substances investigated were: /sup 14/C-urea, /sup 3/H-mannose, /sup 3/H-inulin, and /sup 125/I polyvinylpyrrolidone (PVP). Small bowel biopsies were taken at intervals from one to 60 minutes after injection and the tissues processed for autoradiography. Light microscopic examination of the autoradiographs showed that the compartmental distribution depended on the molecular size of the substances being studied. Urea and mannose, as small solutes, were uniformly distributed throughout the intravascular, extravascular, and epithelial compartments. Inulin was evenly distributed in the vessel lumen and extravascular space but there was a considerable drop in concentration in the epithelium. PVP exhibited the most marked gradients, the concentration being greatest in the vascular lumina, lower in the extravascular space, least in the epithelium. Thus there appear to be two barriers to macromolecular passage which are freely permeable to small solutes: the capillary wall and the epithelium. At a light microscopical level it was not possible to observe whether the limiting membrane of each of these barriers is the cell plasmalemmal membrane or the basement membrane. The selectivity of the epithelial barrier was greater than that of the capillary barrier.

Magnetically controlled permeability membranes

KAUST Repository

Kosel, Jurgen

2013-10-31

A bioactive material delivery system can include a thermoresponsive polymer membrane and nanowires distributed within the thermoresponsive polymer membrane. Magnetic activation of a thermoresponsive polymer membrane can take place via altering the magnetization or dimensions of nanowires dispersed or ordered within the membrane matrix.

Magnetically controlled permeability membranes

KAUST Repository

Kosel, Jü rgen; Khashab, Niveen M.; Zaher, Amir

2013-01-01

A bioactive material delivery system can include a thermoresponsive polymer membrane and nanowires distributed within the thermoresponsive polymer membrane. Magnetic activation of a thermoresponsive polymer membrane can take place via altering the magnetization or dimensions of nanowires dispersed or ordered within the membrane matrix.

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.

Membrane permeability of the human granulocyte to water, dimethyl sulfoxide, glycerol, propylene glycol and ethylene glycol.

Science.gov (United States)

Vian, Alex M; Higgins, Adam Z

2014-02-01

Granulocytes are currently transfused as soon as possible after collection because they rapidly deteriorate after being removed from the body. This short shelf life complicates the logistics of granulocyte collection, banking, and safety testing. Cryopreservation has the potential to significantly increase shelf life; however, cryopreservation of granulocytes has proven to be difficult. In this study, we investigate the membrane permeability properties of human granulocytes, with the ultimate goal of using membrane transport modeling to facilitate development of improved cryopreservation methods. We first measured the equilibrium volume of human granulocytes in a range of hypo- and hypertonic solutions and fit the resulting data using a Boyle-van't Hoff model. This yielded an isotonic cell volume of 378 μm(3) and an osmotically inactive volume of 165 μm(3). To determine the permeability of the granulocyte membrane to water and cryoprotectant (CPA), cells were injected into well-mixed CPA solution while collecting volume measurements using a Coulter Counter. These experiments were performed at temperatures ranging from 4 to 37°C for exposure to dimethyl sulfoxide, glycerol, ethylene glycol, and propylene glycol. The best-fit water permeability was similar in the presence of all of the CPAs, with an average value at 21°C of 0.18 μmatm(-1)min(-1). The activation energy for water transport ranged from 41 to 61 kJ/mol. The CPA permeability at 21°C was 6.4, 1.0, 8.4, and 4.0 μm/min for dimethyl sulfoxide, glycerol, ethylene glycol, and propylene glycol, respectively, and the activation energy for CPA transport ranged between 59 and 68 kJ/mol. Copyright © 2013 Elsevier Inc. All rights reserved.

Sulfonated graphene oxide/nafion composite membrane for vanadium redox flow battery.

Science.gov (United States)

Kim, Byung Guk; Han, Tae Hee; Cho, Chang Gi

2014-12-01

Nafion is the most frequently used as the membrane material due to its good proton conductivity, and excellent chemical and mechanical stabilities. But it is known to have poor barrier property due to its well-developed water channels. In order to overcome this drawback, graphene oxide (GO) derivatives were introduced for Nafion composite membranes. Sulfonated graphene oxide (sGO) was prepared from GO. Both sGO and GO were treated each with phenyl isocyanate and transformed into corresponding isGO and iGO in order to promote miscibility with Nafion. Then composite membranes were obtained, and the adaptability as a membrane for vanadium redox flow battery (VRFB) was investigated in terms of proton conductivity and vanadium permeability. Compared to a pristine Nafion, proton conductivities of both isGO/Nafion and iGO/Nafion membranes showed less temperature sensitivity. Both membranes also showed quite lower vanadium permeability at room temperature. Selectivity of the membrane was the highest for isGO/Nafion and the lowest for the pristine Nafion.

Ion permeability of the cytoplasmic membrane limits the maximum growth temperature of bacteria and archaea

NARCIS (Netherlands)

van de Vossenberg, J.L C M; Ubbink-Kok, T.; Elferink, M.G.L.; Driessen, A.J.M.; Konings, W.N

1995-01-01

Protons and sodium ions are the most commonly used coupling ions in energy transduction in bacteria and archaea. At their growth temperature, the permeability of the cytoplasmic membrane of thermophilic bacteria to protons is high compared with that of sodium ions. In some thermophiles, sodium is

Effects of propranolol and clonidine on brain edema, blood-brain barrier permeability, and endothelial glycocalyx disruption after fluid percussion brain injury in the rat

DEFF Research Database (Denmark)

Genét, Gustav Folmer; Bentzer, Peter; Hansen, Morten Bagge

2018-01-01

clonidine would decrease brain edema, blood-brain barrier permeability, and glycocalyx disruption at 24 hours after trauma. METHODS: We subjected 53 adult male Sprague-Dawley rats to lateral fluid percussion brain injury and randomized infusion with propranolol (n = 16), propranolol + clonidine (n = 16......), vehicle (n = 16), or sham (n = 5) for 24 hours. Primary outcome was brain water content at 24 hours. Secondary outcomes were blood-brain barrier permeability and plasma levels of syndecan-1 (glycocalyx disruption), cell damage (histone-complexed DNA fragments), epinephrine, norepinephrine, and animal.......555). We found no effect of propranolol and propranolol/clonidine on blood-brain barrier permeability and animal motor scores. Unexpectedly, propranolol and propranolol/clonidine caused an increase in epinephrine and syndecan-1 levels. CONCLUSION: This study does not provide any support for unselective...

Vascular endothelial growth factors enhance the permeability of the mouse blood-brain barrier.

Directory of Open Access Journals (Sweden)

Shize Jiang

Full Text Available The blood-brain barrier (BBB impedes entry of many drugs into the brain, limiting clinical efficacy. A safe and efficient method for reversibly increasing BBB permeability would greatly facilitate central nervous system (CNS drug delivery and expand the range of possible therapeutics to include water soluble compounds, proteins, nucleotides, and other large molecules. We examined the effect of vascular endothelial growth factor (VEGF on BBB permeability in Kunming (KM mice. Human VEGF165 was administered to treatment groups at two concentrations (1.6 or 3.0 µg/mouse, while controls received equal-volume saline. Changes in BBB permeability were measured by parenchymal accumulation of the contrast agent Gd-DTPA as assessed by 7 T magnetic resonance imaging (MRI. Mice were then injected with Evans blue, sacrificed 0.5 h later, and perfused transcardially. Brains were removed, fixed, and sectioned for histological study. Both VEGF groups exhibited a significantly greater signal intensity from the cerebral cortex and basal ganglia than controls (P<0.001. Evans blue fluorescence intensity was higher in the parenchyma and lower in the cerebrovasculature of VEGF-treated animals compared to controls. No significant brain edema was observed by diffusion weighted MRI (DWI or histological staining. Exogenous application of VEGF can increase the permeability of the BBB without causing brain edema. Pretreatment with VEGF may be a feasible method to facilitate drug delivery into the CNS.

Influence of CO2 on electrophysiology and ionic permeability of the basolateral membrane of frog skin

International Nuclear Information System (INIS)

Stoddard, J.S.

1984-01-01

When short-circuited epithelia of frog skin bathed in an alkaline Ringer solution equilibrated with room air, are exposed to a Ringer solution equilibrated with 5% CO 2 , inhibition of transepithelial Na + transport is observed accompanied by a marked depolarization of the basolateral membrane voltage as measured with intracellular microelectrodes. To study further the mechanisms involved, basolateral membrane influxes and effluxes of 24 Na, 42 K, and 36 Cl were measured in control and CO 2 -treated isolated epithelia. In control epithelia, studies of the bidirectional 24 Na fluxes confirmed the existence of an important basolateral membrane permeability to Na + . In control epithelia, the apical membranes of the cells were found to be virtually impermeable to Cl - , while basolateral membranes were highly permeable to Cl - . Although CO 2 caused a partial inhibition of pump activity as assessed from decreases of pump-mediated Na + efflux and K + influx, CO 2 caused little or no change of the leak influx of Na + or K + . K + efflux was increased markedly with CO 2 resulting in a net loss of K + from the cells. Cl - influx was increased and Cl - efflux was decreased by CO 2 leading to a net influx of Cl - . Analysis of the data according to criteria involving changes of flux, ionic equilibrium potentials, mass and charge balance restrictions indicated that the principle changes involve a transient decrease in electrical conductance to K + with a concurrent increase in electrical conductance to HCO 3 - (OH - or H + ) of the basolateral membranes of the cells

Transformation of Reactive Iron Minerals in a Permeable Reactive Barrier (Biowall) Used to Treat TCE in Groundwater

Science.gov (United States)

Abstract: Iron and sulfur reducing conditions are generally created in permeable reactive barrier (PRB) systems constructed for groundwater treatment, which usually leads to formation of iron sulfide phases. Iron sulfides have been shown to play an important role in degrading ch...

Bone conditioned media (BCM) improves osteoblast adhesion and differentiation on collagen barrier membranes.

Science.gov (United States)

Fujioka-Kobayashi, Masako; Caballé-Serrano, Jordi; Bosshardt, Dieter D; Gruber, Reinhard; Buser, Daniel; Miron, Richard J

2016-07-04

The use of autogenous bone chips during guided bone regeneration procedures has remained the gold standard for bone grafting due to its excellent combination of osteoconduction, osteoinduction and osteogenesis. Recent protocols established by our group have characterized specific growth factors and cytokines released from autogenous bone that have the potential to be harvested and isolated into bone conditioned media (BCM). Due to the advantageous osteo-promotive properties of BCM, the aims of the present study was to pre-coat collagen barrier membranes with BCM and investigate its effect on osteoblast adhesion, proliferation and differentiation for possible future clinical use. Scanning electron microscopy (SEM) was first used to qualitative assess BCM protein accumulation on the surface of collagen membranes. Thereafter, undifferentiated mouse ST2 stromal bone marrow cells were seeded onto BioGide porcine derived collagen barrier membranes (control) or barrier membranes pre-coated with BCM (test group). Control and BCM samples were compared for cell adhesion at 8 h, cell proliferation at 1, 3 and 5 days and real-time PCR at 5 days for osteoblast differentiation markers including Runx2, alkaline phosphatase (ALP), osteocalcin (OCN) and bone sialoprotein (BSP). Mineralization was further assessed with alizarin red staining at 14 days post seeding. SEM images demonstrated evidence of accumulated proteins found on the surface of collagen membranes following coating with BCM. Analysis of total cell numbers revealed that the additional pre-coating with BCM markedly increased cell attachment over 4 fold when compared to cells seeded on barrier membranes alone. No significant difference could be observed for cell proliferation at all time points. BCM significantly increased mRNA levels of osteoblast differentiation markers including ALP, OCN and BSP at 5 days post seeding. Furthermore, barrier membranes pre-coated with BCM demonstrated a 5-fold increase in alizarin

基于压水试验的深部煤层底板岩层阻渗性能研究∗%Study on permeability barrier performance of deep coal seam floor based on packer permeability test

Institute of Scientific and Technical Information of China (English)

孙晓倩; 张冬; 张新武; 王言剑

2014-01-01

In situ field packer permeability test,being a reliable method to obtain the param-eters of permeability barrier performance of strata,was used to explore this performance of deep coal seam floor. A large amount of measured data were obtained after the test on two layers of floor strata. The test results showed that these two layers of floor strata could not seep in initial state due to stronger barrier performance until the fracture and connection led to seepage. Co MPared with the first and repeated packer permeability tests on these two layers of floor strata, the variation of water pressure in measured pore was associated with that in water injection hole, but the seepage pressure in the first time was higher than that in second time,showing that the permeability barrier performance of strata turned weaker after first packer permeability test and was easy to form seepage. Using permeability coefficient and permeability barrier strength as in-dexes,the permeability barrier performance of floor strata has been quantitatively evaluated,and the results showed that the tested strata was characterized with high barrier performance and weak permeability.%原位现场压水试验是获取岩层阻渗性能参数的可靠方法，为探究某煤矿深部煤层底板阻渗能力，采用现场压水试验方法对底板两段岩层进行了测试并获取了大量的实测数据。结果分析表明：该底板两测试段岩层在原始状态均不导渗，阻渗性较强，直至压裂导通才形成导渗条件；对两段岩层均进行了初次和重复两个压水过程，对比两次试验可知，测渗孔水压力与注水孔水压力的关联变化趋势大致相同，但初次压水的起始导渗水压明显高于重复压水，表明在初次压水后岩层的阻渗能力降低，更易形成导渗；采用渗透系数和阻渗强度作为指标，对底板岩层的阻渗性能进行了量化评价，结果表明测试岩层表现出明显的高阻弱渗的特点。

Free flow zone electrophoresis and isoelectric focusing using a microfabricated glass device with ion permeable membranes

NARCIS (Netherlands)

Kohlheyer, D.; Besselink, G.A.J.; Schlautmann, Stefan; Schasfoort, Richardus B.M.

2006-01-01

This paper describes a microfabricated free-flow electrophoresis device with integrated ion permeable membranes. In order to obtain continuous lanes of separated components an electrical field is applied perpendicular to the sample flow direction. This sample stream is sandwiched between two sheath

Flame Retardancy Effects of Graphene Nanoplatelet/Carbon Nanotube Hybrid Membranes on Carbon Fiber Reinforced Epoxy Composites

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Dongxian Zhuo

2013-01-01

Full Text Available Carbon nanotube/graphene nanoplatelet (MWCNT/GNP hybrid membranes with lower liquid permeability and better barrier effect compared to MWCNT membranes were successfully synthesized by vacuum filtering. Their morphologies, water permeability, and pore structures were characterized by a scanning electron microscope (SEM and nitrogen adsorption isotherms. Furthermore, MWCNT/GNP membranes were used to improve the flame retardancy of carbon fiber reinforced polymer (CFRP composites, and the influence of weight percentage of GNPs on the permeability and flame retardancy of MWCNT/GNP membranes was systematically investigated. Results show that incorporation of MWCNT/GNP membranes on CFRP composite plates can remarkably improve the flame retardancy of CFRP composites. Specifically, the incorporation of hierarchical MWCNT/GNP membrane with 7.5 wt% of GNP displays a 35% reduction in the peak heat release rate (PHRR for a CFRP composite plate with the epoxy as matrix and a 11% reduction in PHRR compared with the incorporation of MWCNT membrane only. A synergistic flame retarding mechanism is suggested to be attributed to these results, which includes controlling the pore size and penetrative network structure.

Tuning Liposome Membrane Permeability by Competitive Peptide Dimerization and Partitioning-Folding Interactions Regulated by Proteolytic Activity

Science.gov (United States)

Lim, Seng Koon; Sandén, Camilla; Selegård, Robert; Liedberg, Bo; Aili, Daniel

2016-02-01

Membrane active peptides are of large interest for development of drug delivery vehicles and therapeutics for treatment of multiple drug resistant infections. Lack of specificity can be detrimental and finding routes to tune specificity and activity of membrane active peptides is vital for improving their therapeutic efficacy and minimize harmful side effects. We describe a de novo designed membrane active peptide that partition into lipid membranes only when specifically and covalently anchored to the membrane, resulting in pore-formation. Dimerization with a complementary peptide efficiently inhibits formation of pores. The effect can be regulated by proteolytic digestion of the inhibitory peptide by the matrix metalloproteinase MMP-7, an enzyme upregulated in many malignant tumors. This system thus provides a precise and specific route for tuning the permeability of lipid membranes and a novel strategy for development of recognition based membrane active peptides and indirect enzymatically controlled release of liposomal cargo.

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

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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.

Transport of Zn(OH)4(-2) ions across a polyolefin microporous membrane

Science.gov (United States)

Krejci, Ivan; Vanysek, Peter; Trojanek, Antonin

1993-04-01

Transport of ZN(OH)4(2-) ions through modified microporous polypropylene membranes (Celgard 3401, 350140) was studied using polarography and conductometry. Soluble Nafion as an ion exchange modifying agent was applied to the membrane by several techniques. The influence of Nafion and a surfactant on transport of zinc ions through the membrane was studied. A relationship between membrane impedance and the rate of Zn(OH)4(2-) transport was found. The found correlation between conductivity, ion permeability and Nafion coverage suggests a suitable technique of membrane preparation to obtain desired zinc ion barrier properties.

Determination of glucose exchange rates and permeability of erythrocyte membrane in preeclampsia and subsequent oxidative stress-related protein damage using dynamic-{sup 19}F-NMR

Energy Technology Data Exchange (ETDEWEB)

Dickinson, Elizabeth, E-mail: elizabeth.dickinson@york.ac.uk [University of York, Department of Chemistry (United Kingdom); Arnold, John R. P. [Selby College (United Kingdom); Fisher, Julie [University of Leeds, School of Chemistry (United Kingdom)

2017-02-15

The cause of the pregnancy condition preeclampsia (PE) is thought to be endothelial dysfunction caused by oxidative stress. As abnormal glucose tolerance has also been associated with PE, we use a fluorinated-mimic of this metabolite to establish whether any oxidative damage to lipids and proteins in the erythrocyte membrane has increased cell membrane permeability. Data were acquired using {sup 19}F Dynamic-NMR (DNMR) to measure exchange of 3-fluoro-3-deoxyglucose (3-FDG) across the membrane of erythrocytes from 10 pregnant women (5 healthy control women, and 5 from women suffering from PE). Magnetisation transfer was measured using the 1D selective inversion and 2D EXSY pulse sequences, over a range of time delays. Integrated intensities from these experiments were used in matrix diagonalisation to estimate the values of the rate constants of exchange and membrane permeability. No significant differences were observed for the rate of exchange of 3-FDG and membrane permeability between healthy pregnant women and those suffering from PE, leading us to conclude that no oxidative damage had occurred at this carrier-protein site in the membrane.

Determination of glucose exchange rates and permeability of erythrocyte membrane in preeclampsia and subsequent oxidative stress-related protein damage using dynamic-"1"9F-NMR

International Nuclear Information System (INIS)

Dickinson, Elizabeth; Arnold, John R. P.; Fisher, Julie

2017-01-01

The cause of the pregnancy condition preeclampsia (PE) is thought to be endothelial dysfunction caused by oxidative stress. As abnormal glucose tolerance has also been associated with PE, we use a fluorinated-mimic of this metabolite to establish whether any oxidative damage to lipids and proteins in the erythrocyte membrane has increased cell membrane permeability. Data were acquired using "1"9F Dynamic-NMR (DNMR) to measure exchange of 3-fluoro-3-deoxyglucose (3-FDG) across the membrane of erythrocytes from 10 pregnant women (5 healthy control women, and 5 from women suffering from PE). Magnetisation transfer was measured using the 1D selective inversion and 2D EXSY pulse sequences, over a range of time delays. Integrated intensities from these experiments were used in matrix diagonalisation to estimate the values of the rate constants of exchange and membrane permeability. No significant differences were observed for the rate of exchange of 3-FDG and membrane permeability between healthy pregnant women and those suffering from PE, leading us to conclude that no oxidative damage had occurred at this carrier-protein site in the membrane.

Fine-Tuned Intrinsically Ultramicroporous Polymers Redefine the Permeability/Selectivity Upper Bounds of Membrane-Based Air and Hydrogen Separations

KAUST Repository

Swaidan, Raja

2015-08-20

Intrinsically ultramicroporous (<7 Å) polymers represent a new paradigm in materials development for membrane-based gas separation. In particular, they demonstrate that uniting intrachain “rigidity”, the traditional design metric of highly permeable polymers of intrinsic microporosity (PIMs), with gas-sieving ultramicroporosity yields high-performance gas separation membranes. Highly ultramicroporous PIMs have redefined the state-of-the-art in large-scale air (e.g., O2/N2) and hydrogen recovery (e.g., H2/N2, H2/CH4) applications with unprecedented molecular sieving gas transport properties. Accordingly, presented herein are new 2015 permeability/selectivity “upper bounds” for large-scale commercial membrane-based air and hydrogen applications that accommodate the substantial performance enhancements of recent PIMs over preceding polymers. A subtle balance between intrachain rigidity and interchain spacing has been achieved in the amorphous microstructures of PIMs, fine-tuned using unique bridged-bicyclic building blocks (i.e., triptycene, ethanoanthracene and Tröger’s base) in both ladder and semiladder (e.g., polyimide) structures.

Implementation of a permeable reactive barrier for treatment of groundwater impacted by strontium-90

International Nuclear Information System (INIS)

Przepiora, A.; Bodine, D.; Dollar, P.; Smith, P.

2014-01-01

A funnel and gate permeable reactive barrier (PRB) system was constructed to treat strontium-90 (Sr- 90) in groundwater migrating from a legacy waste disposal area into an adjacent wetland. The PRB system was designed to contain and direct the Sr-90 impacted groundwater into treatment 'gates' containing zeolite using a low permeability 'funnel' sections constructed with soil-bentonite slurry. The constructed PRB met all dimension and permeability specifications. Initial performance monitoring results indicate that the PRB captured the Sr-90 impacted groundwater plume and the beta radiation values in groundwater emerging from the treatment gates ranged from 35 to 86 Becquerel's per litre (Bq/L), equivalent to a reduction by 88% to 99% from the influent values. Those initial performance results were influenced by residual impacts present in the aquifer material prior to PRB installation. It is anticipated that the clean-up target of 5 Bq/L will be achieved with time as treated groundwater emerging from the PRB flushes through the downgradient aquifer zone. (author)

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

Science.gov (United States)

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

2016-06-01

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

Guided bone regeneration : the influence of barrier membranes on bone grafts and bone defects

NARCIS (Netherlands)

Gielkens, Pepijn Frans Marie

2008-01-01

Guided bone regeneration (GBR) can be described as the use of a barrier membrane to provide a space available for new bone formation in a bony defect. The barrier membrane protects the defect from in-growth of soft tissue cells and allows bone progenitor cells to develop bone within a blood clot

Theoretical investigation of gas separation in functionalized nanoporous graphene membranes

Science.gov (United States)

Wang, Yong; Yang, Qingyuan; Zhong, Chongli; Li, Jinping

2017-06-01

Graphene has enormous potential as a membrane-separation material with ultrahigh permeability and selectivity. The understanding of mass-transport mechanism in graphene membranes is crucial for applications in gas separation field. We computationally investigated the capability and mechanisms of functionalized nanoporous graphene membranes for gas separation. The functionalized graphene membranes with appropriate pore size and geometry possess excellent high selectivity for separating CO2/N2, CO2/CH4 and N2/CH4 gas mixtures with a gas permeance of ∼103-105 GPU, compared with ∼100 GPU for typical polymeric membranes. More important, we found that, for ultrathin graphene membranes, the gas separation performance has a great dependence not only with the energy barrier for gas getting into the pore of the graphene membranes, but also with the energy barrier for gas escaping from the pore to the other side of the membranes. The gas separation performance can be tuned by changing the two energy barriers, which can be realized by varying the chemical functional groups on the pore rim of the graphene. The novel mass-transport mechanism obtained in current study may provide a theoretical foundation for guiding the future design of graphene membranes with outstanding separation performance.

Sulfonated Poly(Ether Ether Ketone)/Functionalized Carbon Nanotube Composite Membrane for Vanadium Redox Flow Battery Applications

International Nuclear Information System (INIS)

Jia, Chuankun; Cheng, Yuanhang; Ling, Xiao; Wei, Guanjie; Liu, Jianguo; Yan, Chuanwei

2015-01-01

A novel sulfonated poly(ether ether ketone) (SPEEK) membrane embedded with the short-carboxylic multi-walled carbon nanotube (we name it as SPEEK/SCCT membrane) for vanadium redox flow battery (VRB) has been prepared with low capacity loss, low cost and high energy efficiency. The mechanical strength, vanadium ions permeability and performance of the membrane in the VRB single cell were characterized. Results showed that the SPEEK/SCCT membrane possessed low permeability of vanadium ions, accompanied by higher mechanical strength than the Nafion 212 membrane. The VRB single cell with SPEEK/SCCT membrane showed 7% higher coulombic efficiency (CE), 6% higher energy efficiency (EE) but lower capacity loss in comparison with the one with Nafion 212. The good cell performance, low capacity loss and high vanadium ions barrier properties of the blend membrane is of significant interest for VRB applications

Long-Term Groundwater Monitoring Optimization, Clare Water Supply Superfund Site, Permeable Reactive Barrier and Soil Remedy Areas, Clare, Michigan

Science.gov (United States)

This report contains a review of the long-term groundwater monitoring network for the Permeable Reactive Barrier (PRB) and Soil Remedy Areas at the Clare Water Supply Superfund Site in Clare, Michigan.

Effect of Light-Activated Hypocrellin B on the Growth and Membrane Permeability of Gram-Negative Escherichia coli Cells

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Yuan Jiang

2014-01-01

Full Text Available Aim. To investigate the effect of light-activated hypocrellin B on the growth and membrane permeability of Gram-negative bacteria. Methods. Escherichia coli (E. coli as a model bacterium of Gram-negative bacteria was incubated with various concentrations of hypocrellin B for 60 min and was subsequently irradiated by blue light with wavelength of 470 nm at the dose of 12 J/cm2. Colony forming units were counted and the growth inhibition rate of E. coli cells was calculated after light-activated hypocrellin B. Membrane permeability was measured using flow cytometry and confocal laser scanning microscopy (CLSM with propidium iodide (PI staining. Bacterial morphology was observed using transmission electron microscopy (TEM. Reactive oxygen species in bacterial cells were measured using flow cytometry with DCFH-DA staining. Results. Significant growth inhibition rate of E. coli cells was observed after photodynamic action of hypocrellin B. Remarkable damage to the ultrastructure of E. coli was also observed by TEM. Flow cytometry and CLSM observation showed that light-activated hypocrellin B markedly increased membrane permeability of E. coli. Flow cytometry showed the intracellular ROS increase in E. coli treated by photodynamic action of hypocrellin B. Conclusion. Light-activated hypocrellin B caused intracellular ROS increase and structural damages and inhibited the growth of Gram-negative E. coli cells.

Increase of radiation damage to potassium-ion permeability in E. coli cells with decrease in membrane fluidity

International Nuclear Information System (INIS)

Suzuki, S.

1980-01-01

Membrane lipids of an auxotroph of E. coli requiring unsaturated fatty acid were manipulated by supplementing the growth medium with unsaturated fatty acids of different chain lengths and/or configurations, and the radiation damage to K + -permeability of the resulting modified cells was investigated in relation with factors influencing membrane fluidity, such as temperature and procaine. Radiation had greater effects on membranes supplemented with unsaturated fatty acids of the trans configuration with a longer chain than on those of the cis configuration with a shorter chain. Radiation damage also increased with decrease in temperature. Furthermore, procaine-treated membranes showed increased resistance to radiation. All these results indicate that the damage was affected by the physical character of membrane lipids and that it was greater in membranes with decreased fluidity. (author)

Fine-Tuned Intrinsically Ultramicroporous Polymers Redefine the Permeability/Selectivity Upper Bounds of Membrane-Based Air and Hydrogen Separations

KAUST Repository

Swaidan, Raja; Ghanem, Bader; Pinnau, Ingo

2015-01-01

Intrinsically ultramicroporous (<7 Å) polymers represent a new paradigm in materials development for membrane-based gas separation. In particular, they demonstrate that uniting intrachain “rigidity”, the traditional design metric of highly permeable

Bexarotene reduces blood-brain barrier permeability in cerebral ischemia-reperfusion injured rats.

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Lu Xu

Full Text Available Matrix metalloproteinase-9 (MMP-9 over-expression disrupts the blood-brain barrier (BBB in the ischemic brain. The retinoid X receptor agonist bexarotene suppresses MMP-9 expression in endothelial cells and displays neuroprotective effects. Therefore, we hypothesized that bexarotene may have a beneficial effect on I/R-induced BBB dysfunction.A total of 180 rats were randomized into three groups (n = 60 each: (i a sham-operation group, (ii a cerebral ischemia-reperfusion (I/R group, and (iii an I/R+bexarotene group. Brain water content was measured by the dry wet weight method. BBB permeability was analyzed by Evans Blue staining and the magnetic resonance imaging contrast agent Omniscan. MMP-9 mRNA expression, protein expression, and activity were assessed by reverse transcription polymerase chain reaction, Western blotting, and gelatin zymography, respectively. Apolipoprotein E (apoE, claudin-5, and occludin expression were analyzed by Western blotting.After 24 h, 48 h, and 72 h post-I/R, several effects were observed with bexarotene administration: (i brain water content and BBB permeability were significantly reduced; (ii MMP-9 mRNA and protein expression as well as activity were significantly decreased; (iii claudin-5 and occludin expression were significantly increased; and (iv apoE expression was significantly increased.Bexarotene decreases BBB permeability in rats with cerebral I/R injury. This effect may be due in part to bexarotene's upregulation of apoE expression, which has been previously shown to reduce BBB permeability through suppressing MMP-9-mediated degradation of the tight junction proteins claudin-5 and occludin. This work offers insight to aid future development of therapeutic agents for cerebral I/R injury in human patients.

Tunable hydrogen separation in porous graphene membrane: first-principle and molecular dynamic simulation.

Science.gov (United States)

Tao, Yehan; Xue, Qingzhong; Liu, Zilong; Shan, Meixia; Ling, Cuicui; Wu, Tiantian; Li, Xiaofang

2014-06-11

First-principle density functional theory (DFT) calculation and molecular dynamic (MD) simulation are employed to investigate the hydrogen purification performance of two-dimensional porous graphene material (PG-ESX). First, the pore size of PG-ES1 (3.2775 Å) is expected to show high selectivity of H2 by DFT calculation. Then MD simulations demonstrate the hydrogen purification process of the PG-ESX membrane. The results indicate that the selectivity of H2 over several other gas molecules that often accompany H2 in industrial steam methane reforming or dehydrogenation of alkanes (such as N2, CO, and CH4) is sensitive to the pore size of the membrane. PG-ES and PG-ES1 membranes both exhibit high selectivity for H2 over other gases, but the permeability of the PG-ES membrane is much lower than the PG-ES1 membrane because of the smaller pore size. The PG-ES2 membrane with bigger pores demonstrates low selectivity for H2 over other gases. Energy barrier and electron density have been used to explain the difference of selectivity and permeability of PG-ESX membranes by DFT calculations. The energy barrier for gas molecules passing through the membrane generally increase with the decreasing of pore sizes or increasing of molecule kinetic diameter, due to the different electron overlap between gas and a membrane. The PG-ES1 membrane is far superior to other carbon membranes and has great potential applications in hydrogen purification, energy clean combustion, and making new concept membrane for gas separation.

Mass transport of direct methanol fuel cell species in sulfonated poly(ether ether ketone) membranes

International Nuclear Information System (INIS)

Silva, V.S.; Ruffmann, B.; Vetter, S.; Boaventura, M.; Mendes, A.M.; Madeira, L.M.; Nunes, S.P.

2006-01-01

Homogeneous membranes based on sulfonated poly(ether ether ketone) (sPEEK) with different sulfonation degrees (SD) were prepared and characterized. In order to perform a critical analysis of the SD effect on the polymer barrier and mass transport properties towards direct methanol fuel cell species, proton conductivity, water/methanol pervaporation and nitrogen/oxygen/carbon dioxide pressure rise method experiments are proposed. This procedure allows the evaluation of the individual permeability coefficients in hydrated sPEEK membranes with different sulfonation degrees. Nafion[reg] 112 was used as reference material. DMFC tests were also performed at 50 deg. C. It was observed that the proton conductivity and the permeability towards water, methanol, oxygen and carbon dioxide increase with the sPEEK sulfonation degree. In contrast, the SD seems to not affect the nitrogen permeability coefficient. In terms of selectivity, it was observed that the carbon dioxide/oxygen selectivity increases with the sPEEK SD. In contrast, the nitrogen/oxygen selectivity decreases. In terms of barrier properties for preventing the DMFC reactants loss, the polymer electrolyte membrane based on the sulfonated poly(ether ether ketone) with SD lower or equal to 71%, although having slightly lower proton conductivity, presented much better characteristics for fuel cell applications compared with the well known Nafion[reg] 112. In terms of the DMFC tests of the studied membranes at low temperature, the sPEEK membrane with SD = 71% showed to have similar performance, or even better, as that of Nafion[reg] 112. However, the highest DMFC overall efficiency was achieved using sPEEK membrane with SD = 52%

Determination of membrane behaviour during transport of pollutants n clay barriers

International Nuclear Information System (INIS)

Musso, M.; Pejon, O.

2010-01-01

The study of the transport of contaminants in clay barriers had a extensive development in environmental geotechnics. The most studied transport processes are solutes by advection - dispersion and diffusion generated by hydraulic and chemical gradients respectively. Greater attention should be given to the chemical - osmotic flow and behavior membrane clay barriers, since in one case the water molecules move through the existence of a chemical gradient and on the other the means totally or partially inhibits the passage of solutes. The team developed to measure these processes was constructed based on items international literature and performance was verified using two types of materials KCl solution . One material is a bentonite geocomposite (Geosynthetic Clay Liner GCL ) similar to that used by other researchers. The other material is a soil barrier compacted clay (Compacted Clay Liner CCL) Fm. Corumbataí (Permian), belonging to the Paraná basin in the state of Sao Paulo, Brazil . The results show the proper performance of the equipment built . Osmotic pressure generation and membrane performance was verified for both samples. Further corroborated influence of the type of clay mineral in the osmotic pressure generated value and membrane behavior

Ion permeability of artificial membranes evaluated by diffusion potential and electrical resistance measurements.

Science.gov (United States)

Shlyonsky, Vadim

2013-12-01

In the present article, a novel model of artificial membranes that provides efficient assistance in teaching the origins of diffusion potentials is proposed. These membranes are made of polycarbonate filters fixed to 12-mm plastic rings and then saturated with a mixture of creosol and n-decane. The electrical resistance and potential difference across these membranes can be easily measured using a low-cost volt-ohm meter and home-made Ag/AgCl electrodes. The advantage of the model is the lack of ionic selectivity of the membrane, which can be modified by the introduction of different ionophores to the organic liquid mixture. A membrane treated with the mixture containing valinomycin generates voltages from -53 to -25 mV in the presence of a 10-fold KCl gradient (in to out) and from -79 to -53 mV in the presence of a bi-ionic KCl/NaCl gradient (in to out). This latter bi-ionic gradient potential reverses to a value from +9 to +20 mV when monensin is present in the organic liquid mixture. Thus, the model can be build stepwise, i.e., all factors leading to the development of diffusion potentials can be introduced sequentially, helping students to understand the quantitative relationships of ionic gradients and differential membrane permeability in the generation of cell electrical signals.

Membrane organization determines barrier properties of endothelial cells and short-chain sphingolipid-facilitated doxorubicin influx.

Science.gov (United States)

van Hell, A J; Klymchenko, A; Gueth, D M; van Blitterswijk, W J; Koning, G A; Verheij, M

2014-09-01

The endothelial lining and its outer lipid membrane are the first major barriers drug molecules encounter upon intravenous administration. Our previous work identified lipid analogs that counteract plasma membrane barrier function for a series of amphiphilic drugs. For example, short-chain sphingolipids (SCS), like N-octanoyl-glucosylceramide, effectively elevated doxorubicin accumulation in tumor cells, both in vitro and in vivo, and in endothelial cells, whereas other (normal) cells remained unaffected. We hypothesize here that local membrane lipid composition and the degree of lipid ordering define SCS efficacy in individual cells. To this end, we study the differential effect of SCS on bovine aortic endothelial cells (BAEC) in its confluent versus proliferative state, as a model system. While their (plasma membrane) lipidome stays remarkably unaltered when BAECs reach confluency, their lipids segregate to form apical and basolateral domains. Using probe NR12S, we reveal that lipids in the apical membrane are more condensed/liquid-ordered. SCS preferentially attenuate the barrier posed by these condensed membranes and facilitate doxorubicin influx in these particular membrane regions. We confirm these findings in MDCK cells and artificial membranes. In conclusion, SCS-facilitated drug traversal acts on condensed membrane domains, elicited by confluency in resting endothelium. Copyright © 2014 Elsevier B.V. All rights reserved.

Effect of Exercise Intensity on Neurotrophic Factors and Blood-Brain Barrier Permeability Induced by Oxidative-Nitrosative Stress in Male College Students.

Science.gov (United States)

Roh, Hee-Tae; Cho, Su-Youn; Yoon, Hyung-Gi; So, Wi-Young

2017-06-01

We investigated the effects of aerobic exercise intensity on oxidative-nitrosative stress, neurotrophic factor expression, and blood-brain barrier (BBB) permeability. Fifteen healthy men performed treadmill running under low-intensity (LI), moderate-intensity (MI), and high-intensity (HI) conditions. Blood samples were collected immediately before exercise (IBE), immediately after exercise (IAE), and 60 min after exercise (60MAE) to examine oxidative-nitrosative stress (reactive oxygen species [ROS]; nitric oxide [NO]), neurotrophic factors (brain-derived neurotrophic factor [BDNF]; nerve growth factor [NGF]), and blood-brain barrier (BBB) permeability (S-100β; neuron-specific enolase). ROS concentration significantly increased IAE and following HI (4.9 ± 1.7 mM) compared with that after LI (2.8 ± 1.4 mM) exercise (p exercise (p exercise (p exercise (p exercise (p .05). Moderate- and/or high-intensity exercise may induce higher oxidative-nitrosative stress than may low-intensity exercise, which can increase peripheral neurotrophic factor levels by increasing BBB permeability.

Bacterial community succession during pig manure and wheat straw aerobic composting covered with a semi-permeable membrane under slight positive pressure.

Science.gov (United States)

Ma, Shuangshuang; Fang, Chen; Sun, Xiaoxi; Han, Lujia; He, Xueqin; Huang, Guangqun

2018-07-01

Bacteria play an important role in organic matter degradation and maturity during aerobic composting. This study analyzed composting with or without a membrane cover in laboratory-scale aerobic composting reactor systems. 16S rRNA gene analysis was used to study the bacterial community succession during composting. The richness of the bacterial community decreased and the diversity increased after covering with a semi-permeable membrane and applying a slight positive pressure. Principal components analysis based on operational taxonomic units could distinguish the main composting phases. Linear Discriminant Analysis Effect Size analysis indicated that covering with a semi-permeable membrane reduced the relative abundance of anaerobic Clostridiales and pathogenic Pseudomonas and increased the abundance of Cellvibrionales. In membrane-covered aerobic composting systems, the relative abundance of some bacteria could be affected, especially anaerobic bacteria. Covering could effectively promote fermentation, reduce emissions and ensure organic fertilizer quality. Copyright © 2018 Elsevier Ltd. All rights reserved.

Retention behavior of flavonoids on immobilized artificial membrane chromatography and correlation with cell-based permeability.

Science.gov (United States)

Tsopelas, Fotios; Tsagkrasouli, Maria; Poursanidis, Pavlos; Pitsaki, Maria; Vasios, George; Danias, Panagiotis; Panderi, Irene; Tsantili-Kakoulidou, Anna; Giaginis, Constantinos

2018-03-01

The aim of the study was to investigate the immobilized artificial membrane (IAM) retention mechanism for a set of flavonoids and to evaluate the potential of IAM chromatography to model Caco-2 permeability. For this purpose, the retention behavior of 41 flavonoid analogs on two IAM stationary phases, IAM.PC.MG and IAM.PC.DD2, was investigated. Correlations between retention factors, logk w(IAM) and octanol-water partitioning (logP) were established and the role of hydroxyl groups of flavonoids to the underlying retention mechanism was explored. IAM retention and logP values were used to establish sound linear models with Caco-2 permeability (logP app ) taken from the literature. Both stepwise regression and multivariate analysis confirmed the contribution of hydrogen bond descriptors, as additional parameters in the either logk w(IAM) or logP models. Retention factors on both IAM stationary phases showed comparable performance with n-octanol-water partitioning towards Caco-2 permeability. Copyright © 2017 John Wiley & Sons, Ltd.

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.

The long noncoding RNA TUG1 regulates blood-tumor barrier permeability by targeting miR-144.

Science.gov (United States)

Cai, Heng; Xue, Yixue; Wang, Ping; Wang, Zhenhua; Li, Zhen; Hu, Yi; Li, Zhiqing; Shang, Xiuli; Liu, Yunhui

2015-08-14

Blood-tumor barrier (BTB) limits the delivery of chemotherapeutic agent to brain tumor tissues. Long non-coding RNAs (lncRNAs) have been shown to play critical regulatory roles in various biologic processes of tumors. However, the role of lncRNAs in BTB permeability is unclear. LncRNA TUG1 (taurine upregulated gene 1) was highly expressed in glioma vascular endothelial cells from glioma tissues. It also upregulated in glioma co-cultured endothelial cells (GEC) from BTB model in vitro. Knockdown of TUG1 increased BTB permeability, and meanwhile down-regulated the expression of the tight junction proteins ZO-1, occludin, and claudin-5. Both bioinformatics and luciferase reporter assays demonstrated that TUG1 influenced BTB permeability via binding to miR-144. Furthermore, Knockdown of TUG1 also down-regulated Heat shock transcription factor 2 (HSF2), a transcription factor of the heat shock transcription factor family, which was defined as a direct and functional downstream target of miR-144. HSF2 up-regulated the promoter activities and interacted with the promoters of ZO-1, occludin, and claudin-5 in GECs. In conclusion, our results indicate that knockdown of TUG1 increased BTB permeability via binding to miR-144 and then reducing EC tight junction protein expression by targeting HSF2. Thus, TUG1 may represent a useful future therapeutic target for enhancing BTB permeability.

Identification of two immortalized cell lines, ECV304 and bEnd3, for in vitro permeability studies of blood-brain barrier.

Directory of Open Access Journals (Sweden)

Shu Yang

Full Text Available To identify suitable cell lines for a mimetic system of in vivo blood-brain barrier (BBB for drug permeability assessment, we characterized two immortalized cell lines, ECV304 and bEnd3 in the respect of the tightness, tight junction proteins, P-glycoprotein (P-gp function and discriminative brain penetration. The ECV304 monoculture achieved higher transendothelial electrical resistance (TEER and lower permeability to Lucifer yellow than bEnd3. However, co-culture with rat glioma C6 cells impaired the integrity of ECV304 and bEnd3 cell layers perhaps due to the heterogeneity among C6 cells in inducing BBB characteristics. The immunostaining of ZO-1 delivered distinct bands along cell borders on both cell lines while those of occludin and claudin-5 were diffused and weak. P-gp functionality was only proved in bEnd3 by Rhodamine 123 (R123 uptake assay. A permeability test of reference compounds displayed a similar rank order (digoxin < R123 < quinidine, verapamil < propranolol in ECV304 and bEnd3 cells. In comparison with bEnd3, ECV304 developed tighter barrier for the passage of reference compounds and higher discrimination between transcellular and paracellular transport. However, the monoculture models of ECV304 and bEnd3 fail to achieve the sufficient tightness of in vitro BBB permeability models with high TEER and evident immunostaining of tight junction proteins. Further strategies to enhance the paracellular tightness of both cell lines to mimic in vivo BBB tight barrier deserve to be conducted.

Micelle-template synthesis of hollow silica spheres for improving water vapor permeability of waterborne polyurethane membrane

Science.gov (United States)

Bao, Yan; Wang, Tong; Kang, Qiaoling; Shi, Chunhua; Ma, Jianzhong

2017-04-01

Hollow silica spheres (HSS) with special interior spaces, high specific surface area and excellent adsorption and permeability performance were synthesized via micelle-template method using cetyl trimethyl ammonium bromide (CTAB) micelles as soft template and tetraethoxysilane (TEOS) as silica precursor. SEM, TEM, FT-IR, XRD, DLS and BET-BJH were carried out to characterize the morphology and structure of as-obtained samples. The results demonstrated that the samples were amorphous with a hollow structure and huge specific surface area. The growth of HSS was an inward-growth mechanism along template. Notably, we have provided a new and interesting fundamental principle for HSS materials by precisely controlling the ethanol-to-water volume ratio. In addition, the as-obtained HSS were mixed with waterborne polyurethane (WPU) to prepare WPU/HSS composite membrane. Various characterizations (SEM, TEM, FT-IR and TGA) revealed the morphology, polydispersity and adherence between HSS and WPU. Performance tests showed that the introduction of HSS can improve the water vapor permeability of composite membrane, promoting its water resistance and mechanical performance at the same time.

Guided bone regeneration in rat mandibular defects using resorbable poly(trimethylene carbonate) barrier membranes

NARCIS (Netherlands)

van Leeuwen, A. C.; Huddleston Slater, J. J. R.; Gielkens, P. F. M.; de Jong, J. R.; Grijpma, D. W.; Bos, R. R. M.

The present study evaluates a new synthetic degradable barrier membrane based on poly(trimethylene carbonate) (PTMC) for use in guided bone regeneration. A collagen membrane and an expanded polytetrafluoroethylene (e-PTFE) membrane served as reference materials. In 192 male Sprague-Dawley rats, a

Guided bone regeneration in rat mandibular defects using resorbable poly(trimethylene carbonate) barrier membranes

NARCIS (Netherlands)

van Leeuwen, A.C.; Huddelston Slater, J.J.R.; Gielkens, P.F.M.; de Jong, J.R.; Grijpma, Dirk W.; Bos, R.R.M.

2012-01-01

The present study evaluates a new synthetic degradable barrier membrane based on poly(trimethylene carbonate) (PTMC) for use in guided bone regeneration. A collagen membrane and an expanded polytetrafluoroethylene (e-PTFE) membrane served as reference materials. In 192 male Sprague–Dawley rats, a

Metal ion separations using reactive membranes

International Nuclear Information System (INIS)

Way, J.D.

1993-01-01

A membrane is a barrier between two phases. If one component of a mixture moves through the membrane faster than another mixture component, a separation can be accomplished. Membranes are used commercially for many applications including gas separations, water purification, particle filtration, and macromolecule separations (Abelson). There are two points to note concerning this definition. First, a membrane is defined based on its function, not the material used to make the membrane. Secondly, a membrane separation is a rate process. The separation is accomplished by a driving force, not by equilibrium between phases. Liquids that are immiscible with the feed and product streams can also be used as membrane materials. Different solutes will have different solubilities and diffusion coefficients in a liquid. The product of the diffusivity and the solubility is known as the permeability coefficient, which is proportional to the solute flux. Differences in permeability coefficient will produce a separation between solutes at constant driving force. Because the diffusion coefficients in liquids are typically orders of magnitude higher than in polymers, a larger flux can be obtained. Further enhancements can be accomplished by adding a nonvolatile complexation agent to the liquid membrane. One can then have either coupled or facilitated transport of metal ions through a liquid membrane. The author describes two implementations of this concept, one involving a liquid membrane supported on a microporous membrane, and the other an emulsion liquid membrane, where separation occurs to internal receiving phases. Applications and costing studies for this technology are reviewed, and a brief summary of some of the problems with liquid membranes is presented

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

Microporous silica membranes

DEFF Research Database (Denmark)

Boffa, Vittorio; Yue, Yuanzheng

2012-01-01

Hydrothermal stability is a crucial factor for the application of microporous silica-based membranes in industrial processes. Indeed, it is well established that steam exposure may cause densification and defect formation in microporous silica membranes, which are detrimental to both membrane...... permeability and selectivity. Numerous previous studies show that microporous transition metal doped-silica membranes are hydrothermally more stable than pure silica membranes, but less permeable. Here we present a quantitative study on the impact of type and concentration of transition metal ions...... on the microporous structure, stability and permeability of amorphous silica-based membranes, providing information on how to design chemical compositions and synthetic paths for the fabrication of silica-based membranes with a well accessible and highly stabile microporous structure....

Highly Hydrophilic Thin-Film Composite Forward Osmosis Membranes Functionalized with Surface-Tailored Nanoparticles

KAUST Repository

Tiraferri, Alberto

2012-09-26

Thin-film composite polyamide membranes are state-of-the-art materials for membrane-based water purification and desalination processes, which require both high rejection of contaminants and high water permeabilities. However, these membranes are prone to fouling when processing natural waters and wastewaters, because of the inherent surface physicochemical properties of polyamides. The present work demonstrates the fabrication of forward osmosis polyamide membranes with optimized surface properties via facile and scalable functionalization with fine-tuned nanoparticles. Silica nanoparticles are coated with superhydrophilic ligands possessing functional groups that impart stability to the nanoparticles and bind irreversibly to the native carboxyl moieties on the membrane selective layer. The tightly tethered layer of nanoparticles tailors the surface chemistry of the novel composite membrane without altering the morphology or water/solute permeabilities of the membrane selective layer. Surface characterization and interfacial energy analysis confirm that highly hydrophilic and wettable membrane surfaces are successfully attained. Lower intermolecular adhesion forces are measured between the new membrane materials and model organic foulants, indicating the presence of a bound hydration layer at the polyamide membrane surface that creates a barrier for foulant adhesion. © 2012 American Chemical Society.

KB-R7943, a plasma membrane Na(+)/Ca(2+) exchanger inhibitor, blocks opening of the mitochondrial permeability transition pore.

Science.gov (United States)

Wiczer, Brian M; Marcu, Raluca; Hawkins, Brian J

2014-01-31

The isothiourea derivative, KB-R7943, inhibits the reverse-mode of the plasma membrane sodium/calcium exchanger and protects against ischemia/reperfusion injury. The mechanism through which KB-R7943 confers protection, however, remains controversial. Recently, KB-R7943 has been shown to inhibit mitochondrial calcium uptake and matrix overload, which may contribute to its protective effects. While using KB-R7943 for this purpose, we find here no evidence that KB-R7943 directly blocks mitochondrial calcium uptake. Rather, we find that KB-R7943 inhibits opening of the mitochondrial permeability transition pore in permeabilized cells and isolated liver mitochondria. Furthermore, we find that this observation correlates with protection against calcium ionophore-induced mitochondrial membrane potential depolarization and cell death, without detrimental effects to basal mitochondrial membrane potential or complex I-dependent mitochondrial respiration. Our data reveal another mechanism through which KB-R7943 may protect against calcium-induced injury, as well as a novel means to inhibit the mitochondrial permeability transition pore. Copyright © 2014 Elsevier Inc. All rights reserved.

Cell-penetrating peptides for drug delivery across membrane barriers

DEFF Research Database (Denmark)

Foged, Camilla; Nielsen, Hanne Moerck

2008-01-01

During the last decade, cell-penetrating peptides have been investigated for their ability to overcome the plasma membrane barrier of mammalian cells for the intracellular or transcellular delivery of cargoes as diverse as low molecular weight drugs, imaging agents, oligonucleotides, peptides......, proteins and colloidal carriers such as liposomes and polymeric nanoparticles. Their ability to cross biological membranes in a non-disruptive way without apparent toxicity is highly desired for increasing drug bioavailability. This review provides an overview of the application of cell......-penetrating peptides as transmembrane drug delivery agents, according to the recent literature, and discusses critical issues and future challenges in relation to fully understanding the fundamental principles of the cell-penetrating peptide-mediated membrane translocation of cargoes and the exploitation...

A modified parallel artificial membrane permeability assay for evaluating the bioconcentration of highly hydrophobic chemicals in fish.

Science.gov (United States)

Kwon, Jung-Hwan; Escher, Beate I

2008-03-01

Low cost in vitro tools are needed at the screening stage of assessment of bioaccumulation potential of new and existing chemicals because the number of chemical substances that needs to be tested highly exceeds the capacity of in vivo bioconcentration tests. Thus, the parallel artificial membrane permeability assay (PAMPA) system was modified to predict passive uptake/ elimination rate in fish. To overcome the difficulties associated with low aqueous solubility and high membrane affinity of highly hydrophobic chemicals, we measured the rate of permeation from the donor poly(dimethylsiloxane)(PDMS) disk to the acceptor PDMS disk through aqueous and PDMS membrane boundary layers and term the modified PAMPA system "PDMS-PAMPA". Twenty chemicals were selected for validation of PDMS-PAMPA. The measured permeability is proportional to the passive elimination rate constant in fish and was used to predict the "minimum" in vivo elimination rate constant. The in vivo data were very close to predicted values except for a few polar chemicals and metabolically active chemicals, such as pyrene and benzo[a]pyrene. Thus, PDMS-PAMPA can be an appropriate in vitro system for nonmetabolizable chemicals. Combination with metabolic clearance rates using a battery of metabolic degradation assays would enhance the applicability for metabolizable chemicals.

A process efficiency assessment of serum protein removal from milk using ceramic graded permeability microfiltration membrane.

Science.gov (United States)

Tremblay-Marchand, D; Doyen, A; Britten, M; Pouliot, Y

2016-07-01

Microfiltration (MF) is a well-known process that can be used in the dairy industry to separate caseins from serum proteins (SP) in skim milk using membranes with a pore diameter of 0.1μm. Graded permeability ceramic membranes have been studied widely as means of improving milk fractionation by overcoming problems encountered with other MF membranes. The ideal operating parameters for process efficiency in terms of membrane selectivity, permeate flux, casein loss, SP transmission, energy consumption, and dilution with water remain to be determined for this membrane. Our objective was to evaluate the effects of transmembrane pressure (TMP), volumetric concentration factor (VCF), and diafiltration on overall process efficiency. Skim milk was processed using a pilot-scale MF system equipped with 0.72-m(2) graded permeability membranes with a pore size of 0.1μm. In the first experiment, in full recycle mode, TMP was set at 124, 152, 179, or 207 kPa by adjusting the permeate pressure at the outlet. Whereas TMP had no significant effect on permeate and retentate composition, 152 kPa was found to be optimal for SP removal during concentration and concentration or diafiltration experiments. When VCF was increased to 3×, SP rejection coefficient increased along with energy consumption and total casein loss, whereas SP removal rate decreased. Diafiltering twice allowed an increase in total SP removal but resulted in a substantial increase in energy consumption and casein loss. It also reduced the SP removal rate by diluting permeate. The membrane surface area required for producing cheese milk by blending whole milk, cream, and MF retentate (at different VCF) was estimated for different cheese milk casein concentrations. For a given casein concentration, the same quantity of permeate and SP would be produced, but less membrane surface area would be needed at a lower retentate VCF. Microfiltration has great potential as a process of adding value to conventional

Permeability of human placenta and fetal membranes to thyrotropin-stimulating hormone in vitro.

Science.gov (United States)

Bajoria, R; Fisk, N M

1998-05-01

We determined the placental transfer of TSH in an in vitro model of dually perfused isolated lobule in 28 human term placentas by adding varying concentrations (5-60 microIU mL(-1)) of TSH as a single bolus dose to the closed maternal circulation. Transmembrane transfer of TSH was also studied by adding 45 microIU mL(-1) to the maternal or fetal compartment of a dual chamber of fetal membranes in culture. Passage of freely diffusible markers creatinine and antipyrine were also studied in this model. TSH concentration was measured by third generation chemiluminescence assay with a sensitivity of 10 mIU mL(-1). In the perfusion experiments, at physiologic concentrations the slow decline of TSH in the maternal circulation was associated with a small linear increase in fetal levels to 0.11 +/- 0.04% of initial dose at 2 h. The placental transfer rate was 0.08 microIU min(-1). Increasing maternal concentrations of TSH were associated with proportional increases in transfer rate (y = 0.002x; R2 = 0.99) and placental uptake (y = 0.01x; R2 = 0.97). The placental permeability of TSH was 2.4 x 10(-4) mL min(-1) g(-1) and was proportional to its coefficients of diffusion in water and molecular size. The transmembrane transfer and permeability of TSH was comparable to those of the placenta. We conclude that TSH crosses the human term placenta and fetal membranes sparingly.

Proton permeability of membranes of Streptococcus faecalis and submitochondrial particles of rats after irradiation

International Nuclear Information System (INIS)

Fomenko, B.S.; Pinchukova, V.A.

1977-01-01

It has been shown that at a changed, by HCl impulse, pH of Streptococcus faecalis suspension and submitochondrial liver particles (SLP) of rats, H + concentration decreases more rapidly in the irradiated bacteria and SLP than in the controls. The curves of energy dependence of accumulation of the penetrating ions were also displaced toward the alkaline zone depending on pH. These effects are suggested to be connected with an increased proton permeability of irradiated membranes

Confirmation tests of construction method and initial performance quality for low permeable engineered barrier in side part of radioactive waste disposal facilities

International Nuclear Information System (INIS)

Yamada, Atsuo; Chijimatsu, Masakazu; Akiyama, Yoshihiro; Komine, Hideo; Iizuka, Atsushi

2016-01-01

As for the low permeable layer, important functions are expected as an engineered barrier of radioactive waste disposal for low-level waste with comparatively high radiation levels. On examining the construction methods of this low permeable layer, it is important to confirm the possibility of the construction in the conditions similar to the actual constructed conditions with a true scale size. Therefore, the construction examination for the side part of the low permeable layer by bentonite and the performance check test of the low permeable layer were carried out. The result of the construction examination showed that the possibility of the construction were confirmed, and the result of performance check test showed that it was possible to ensure the required performance of the low permeable layer, such as hydraulic conductivity. (author)

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.

Blood-brain barrier permeability and brain uptake mechanism of kainic Acid and dihydrokainic Acid

DEFF Research Database (Denmark)

Gynther, Mikko; Petsalo, Aleksanteri; Hansen, Steen Honoré

2015-01-01

tools in various in vivo central nervous system disease models in rodents, as well as being templates in the design of novel ligands affecting the glutamatergic system. Both molecules are highly polar but yet capable of crossing the blood-brain barrier (BBB). We used an in situ rat brain perfusion...... technique to determine the brain uptake mechanism and permeability across the BBB. To determine KA and DHK concentrations in the rat brain, simple and rapid sample preparation and liquid chromatography mass spectrometer methods were developed. According to our results the BBB permeability of KA and DHK...... is low, 0.25 × 10(-6) and 0.28 × 10(-6) cm/s for KA and DHK, respectively. In addition, the brain uptake is mediated by passive diffusion, and not by active transport. Furthermore, the non-specific plasma and brain protein binding of KA and DHK was determined to be low, which means that the unbound drug...

Rebamipide suppresses diclofenac-induced intestinal permeability via mitochondrial protection in mice.

Science.gov (United States)

Diao, Lei; Mei, Qiao; Xu, Jian-Ming; Liu, Xiao-Chang; Hu, Jing; Jin, Juan; Yao, Qiang; Chen, Mo-Li

2012-03-14

To investigate the protective effect and mechanism of rebamipide on small intestinal permeability induced by diclofenac in mice. Diclofenac (2.5 mg/kg) was administered once daily for 3 d orally. A control group received the vehicle by gavage. Rebamipide (100 mg/kg, 200 mg/kg, 400 mg/kg) was administered intragastrically once a day for 3 d 4 h after diclofenac administration. Intestinal permeability was evaluated by Evans blue and the FITC-dextran method. The ultrastructure of the mucosal barrier was evaluated by transmission electron microscopy (TEM). Mitochondrial function including mitochondrial swelling, mitochondrial membrane potential, mitochondrial nicotinamide adenine dinucleotide-reduced (NADH) levels, succinate dehydrogenase (SDH) and ATPase activities were measured. Small intestinal mucosa was collected for assessment of malondialdehyde (MDA) content and myeloperoxidase (MPO) activity. Compared with the control group, intestinal permeability was significantly increased in the diclofenac group, which was accompanied by broken tight junctions, and significant increases in MDA content and MPO activity. Rebamipide significantly reduced intestinal permeability, improved inter-cellular tight junctions, and was associated with decreases in intestinal MDA content and MPO activity. At the mitochondrial level, rebamipide increased SDH and ATPase activities, NADH level and decreased mitochondrial swelling. Increased intestinal permeability induced by diclofenac can be attenuated by rebamipide, which partially contributed to the protection of mitochondrial function.

Towards high water permeability in triazine-framework-based microporous membranes for dehydration of ethanol.

Science.gov (United States)

Tang, Yu Pan; Wang, Huan; Chung, Tai Shung

2015-01-01

The microstructural evolution of a series of triazine framework-based microporous (TFM) membranes under different conditions has been explored in this work. The pristine TFM membrane is in situ fabricated in the course of polymer synthesis via a facile Brønsted-acid-catalyzed cyclotrimerizaiton reaction. The as-synthesized polymer exhibits a microporous network with high thermal stability. The free volume size of the TFM membranes gradually evolved from a unimodal distribution to a bimodal distribution under annealing, as analyzed by positron annihilation lifetime spectroscopy (PALS). The emergence of the bimodal distribution is probably ascribed to the synergetic effect of quenching and thermal cyclization reaction. In addition, the fractional free volume (FFV) of the membranes presents a concave trend with increasing annealing temperature. Vapor sorption tests reveal that the mass transport properties are closely associated with the free volume evolution, which provides an optimal condition for dehydration of biofuels. A promising separation performance with extremely high water permeability has been attained for dehydration of an 85 wt % ethanol aqueous solution at 45 °C. The study on the free volume evolution of the TFM membranes may provide useful insights about the microstructure and mass transport behavior of the microporous polymeric materials. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

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

Science.gov (United States)

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

2017-08-01

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

Effects of impurities on hydrogen permeability through palladium alloy membrane at comparatively high pressure and temperature

International Nuclear Information System (INIS)

Yoshida, Hiroshi; Konishi, Satoshi; Katsuta, Hiroji; Naruse, Yuji

1982-02-01

Palladium alloy membrane method is considered to be a useful technique for fusion reactor fuel purification process. To study the feasibility of this method, the effects of impurities on permeation characteristics of palladium alloy membrane were examined. Experiments were carried out at practical conditions: pressure; 120 - 1200 kPa, temperature; about 700 K. No poisoning effect on hydrogen permeability of commercial Pd-Ag (Au.Ru) alloy was observed for impurities such as NH 3 , CH 4 , CO, CO 2 , O 2 and N 2 , which were mixed with hyper-pure H 2 at low concentration level (10 - 10000 ppm). Deterioration occurred by contamination with oil vapor. However, regeneration of the membrane was easily performed by air baking followed by hydrogen reduction. Chemical reactions in the permeation cell were also examined. (author)

Phosphate barrier on pore-filled cation-exchange membrane for blocking complexing ions in presence of non-complexing ions

Science.gov (United States)

Chavan, Vivek; Agarwal, Chhavi; Shinde, Rakesh N.

2018-06-01

In present work, an approach has been used to form a phosphate groups bearing surface barrier on a cation-exchange membrane (CEM). Using optimized conditions, the phosphate bearing monomer bis[2-(methacryloyloxy)ethyl] phosphate has been grafted on the surface of the host poly(ethersulfone) membranes using UV light induced polymerization. The detailed characterizations have shown that less than a micron layer of phosphate barrier is formed without disturbing the original microporous structure of the host membrane. The pores of thus formed membrane have been blocked by cationic-gel formed by in situ UV-initiator induced polymerization of 2-acrylamido-2-methyl-1-propane sulphonic acid along with crosslinker ethylene glycol dimethacrylate in the pores of the membrane. UV-initiator is required for pore-filling as UV light would not penetrate the interior matrix of the membrane. The phosphate functionalized barrier membrane has been examined for permselectivity using a mixture of representative complexing Am3+ ions and non-complexing Cs+ ions. This experiment has demonstrated that complex forming Am3+ ions are blocked by phosphate barrier layer while non-complexing Cs+ ions are allowed to pass through the channels formed by the crosslinked cationic gel.

Arabidopsis SNAREs SYP61 and SYP121 coordinate the trafficking of plasma membrane aquaporin PIP2;7 to modulate the cell membrane water permeability.

Science.gov (United States)

Hachez, Charles; Laloux, Timothée; Reinhardt, Hagen; Cavez, Damien; Degand, Hervé; Grefen, Christopher; De Rycke, Riet; Inzé, Dirk; Blatt, Michael R; Russinova, Eugenia; Chaumont, François

2014-07-01

Plant plasma membrane intrinsic proteins (PIPs) are aquaporins that facilitate the passive movement of water and small neutral solutes through biological membranes. Here, we report that post-Golgi trafficking of PIP2;7 in Arabidopsis thaliana involves specific interactions with two syntaxin proteins, namely, the Qc-SNARE SYP61 and the Qa-SNARE SYP121, that the proper delivery of PIP2;7 to the plasma membrane depends on the activity of the two SNAREs, and that the SNAREs colocalize and physically interact. These findings are indicative of an important role for SYP61 and SYP121, possibly forming a SNARE complex. Our data support a model in which direct interactions between specific SNARE proteins and PIP aquaporins modulate their post-Golgi trafficking and thus contribute to the fine-tuning of the water permeability of the plasma membrane. © 2014 American Society of Plant Biologists. All rights reserved.

In vivo EPR pharmacokinetic evaluation of the redox status and the blood brain barrier permeability in the SOD1G93A ALS rat model.

Science.gov (United States)

Stamenković, Stefan; Pavićević, Aleksandra; Mojović, Miloš; Popović-Bijelić, Ana; Selaković, Vesna; Andjus, Pavle; Bačić, Goran

2017-07-01

Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disorder affecting the motor pathways of the central nervous system. Although a number of pathophysiological mechanisms have been described in the disease, post mortem and animal model studies indicate blood-brain barrier (BBB) disruption and elevated production of reactive oxygen species as major contributors to disease pathology. In this study, the BBB permeability and the brain tissue redox status of the SOD1 G93A ALS rat model in the presymptomatic (preALS) and symptomatic (ALS) stages of the disease were investigated by in vivo EPR spectroscopy using three aminoxyl radicals with different cell membrane and BBB permeabilities, Tempol, 3-carbamoyl proxyl (3CP), and 3-carboxy proxyl (3CxP). Additionally, the redox status of the two brain regions previously implicated in disease pathology, brainstem and hippocampus, was investigated by spectrophotometric biochemical assays. The EPR results indicated that among the three spin probes, 3CP is the most suitable for reporting the intracellular redox status changes, as Tempol was reduced in vivo within minutes (t 1/2 =2.0±0.5min), thus preventing reliable kinetic modeling, whereas 3CxP reduction kinetics gave divergent conclusions, most probably due to its membrane impermeability. It was observed that the reduction kinetics of 3CP in vivo, in the head of preALS and ALS SOD1 G93A rats was altered compared to the controls. Pharmacokinetic modeling of 3CP reduction in vivo, revealed elevated tissue distribution and tissue reduction rate constants indicating an altered brain tissue redox status, and possibly BBB disruption in these animals. The preALS and ALS brain tissue homogenates also showed increased nitrilation, superoxide production, lipid peroxidation and manganese superoxide dismutase activity, and a decreased copper-zinc superoxide dismutase activity. The present study highlights in vivo EPR spectroscopy as a reliable tool for the investigation of

Ultrathin Ceramic Membranes as Scaffolds for Functional Cell Coculture Models on a Biomimetic Scale

Science.gov (United States)

Jud, Corinne; Ahmed, Sher; Müller, Loretta; Kinnear, Calum; Vanhecke, Dimitri; Umehara, Yuki; Frey, Sabine; Liley, Martha; Angeloni, Silvia; Petri-Fink, Alke; Rothen-Rutishauser, Barbara

2015-01-01

Abstract Epithelial tissue serves as an interface between biological compartments. Many in vitro epithelial cell models have been developed as an alternative to animal experiments to answer a range of research questions. These in vitro models are grown on permeable two-chamber systems; however, commercially available, polymer-based cell culture inserts are around 10 μm thick. Since the basement membrane found in biological systems is usually less than 1 μm thick, the 10-fold thickness of cell culture inserts is a major limitation in the establishment of realistic models. In this work, an alternative insert, accommodating an ultrathin ceramic membrane with a thickness of only 500 nm (i.e., the Silicon nitride Microporous Permeable Insert [SIMPLI]-well), was produced and used to refine an established human alveolar barrier coculture model by both replacing the conventional inserts with the SIMPLI-well and completing it with endothelial cells. The structural–functional relationship of the model was evaluated, including the translocation of gold nanoparticles across the barrier, revealing a higher translocation if compared to corresponding polyethylene terephthalate (PET) membranes. This study demonstrates the power of the SIMPLI-well system as a scaffold for epithelial tissue cell models on a truly biomimetic scale, allowing construction of more functionally accurate models of human biological barriers. PMID:26713225

Acute Acrolein Exposure Induces Impairment of Vocal Fold Epithelial Barrier Function.

Science.gov (United States)

Liu, Xinxin; Zheng, Wei; Sivasankar, M Preeti

2016-01-01

Acrolein is a ubiquitous pollutant abundant in cigarette smoke, mobile exhaust, and industrial waste. There is limited literature on the effects of acrolein on vocal fold tissue, although there are clinical reports of voice changes after pollutant exposures. Vocal folds are responsible for voice production. The overall objective of this study was to investigate the effects of acrolein exposure on viable, excised vocal fold epithelial tissue and to characterize the mechanism underlying acrolein toxicity. Vocal fold epithelia were studied because they form the outermost layer of the vocal folds and are a primary recipient of inhaled pollutants. Porcine vocal fold epithelia were exposed to 0, 50, 100, 500, 900 or 1300 μM of acrolein for 3 hours; the metabolic activity, epithelial resistance, epithelial permeability, tight junction protein (occludin and claudin 3) expression, cell membrane integrity and lipid peroxidation were investigated. The data demonstrated that acrolein exposure at 500 μM significantly reduced vocal fold epithelial metabolic activity by 27.2% (p≤0.001). Incubation with 100 μM acrolein caused a marked increase in epithelial permeability by 130.5% (pacrolein-treated samples, the cell membrane integrity was significantly damaged with a 45.6% increase of lipid peroxidation as compared to controls (pacrolein exposure impairs vocal fold epithelial barrier integrity. Lipid peroxidation-induced cell membrane damage may play an important role in reducing the barrier function of the epithelium.

Adjunctive Effect of Autologus Platelet-Rich Fibrin to Barrier Membrane in the Treatment of Periodontal Intrabony Defects.

Science.gov (United States)

Panda, Saurav; Sankari, Malaiappan; Satpathy, Anurag; Jayakumar, Doraiswamy; Mozzati, Marco; Mortellaro, Carmen; Gallesio, Giorgia; Taschieri, Silvio; Del Fabbro, Massimo

2016-05-01

Autologous platelet-rich fibrin (PRF) and barrier membranes in the treatment of intrabony defects in chronic periodontitis patients have shown significant clinical benefits. This study evaluates the additive effect of autologous PRF in combination with a barrier membrane versus the use of barrier membrane alone for the treatment of intrabony defects in chronic periodontitis patients. A randomized split-mouth design was used. Sixteen patients with 32 paired intrabony defects were included. In each patient 1 defect was treated using a resorbable collagen membrane along with PRF (test group) and the other defect by guided tissue regeneration alone (control group). The following clinical parameters were measured at baseline and after 9 months: plaque index, modified sulcus bleeding index, probing pocket depth, clinical attachment level, and gingival marginal level. The radiographic defect depth was also assessed at baseline and after 9 months. Test group showed a statistically significant improvement for probing depth (P = 0.002), clinical attachment level (P = 0.001), and radiographic defect depth (P < 0.001) after 9 months as compared with the control sites. Radiographic defect depth reduction was 58.19 ± 13.24% in the test group as compared with 24.86 ± 9.94% reduction in the control group. The adjunctive use of PRF in combination with barrier membrane is more effective in the treatment of intrabony defects in chronic periodontitis as compared with barrier membrane alone.

Liposomal membrane disruption by means of miniaturized dielectric-barrier discharge in air: liposome characterization

Science.gov (United States)

Svarnas, P.; Asimakoulas, L.; Katsafadou, M.; Pachis, K.; Kostazos, N.; Antimisiaris, S. G.

2017-08-01

The increasing interest of the plasma community in the application of atmospheric-pressure cold plasmas to bio-specimen treatment has led to the creation of the emerging field of plasma biomedicine. Accordingly, plasma setups based on dielectric-barrier discharges have already been widely tested for the inactivation of various cells. Most of these systems refer to the plasma jet concept where noble gases penetrate atmospheric air and are subjected to the influence of high electric fields, thus forming guided streamers. Following the original works of our group where liposomal membranes were proposed as models for studying the interaction between plasma jets and cells, we present herein a study on liposomal membrane disruption by means of miniaturized dielectric-barrier discharge running in atmospheric air. Liposomal membranes of various lipid compositions, lamellarities, and sizes are treated at different times. It is shown that the dielectric-barrier discharge of low mean power leads to efficient liposomal membrane disruption. The latter is achieved in a controllable manner and depends on liposome properties. Additionally, it is clearly demonstrated that liposomal membrane disruption takes place even after plasma extinction, i.e. during post-treatment, resembling thus an ‘apoptosis’ effect, which is well known today mainly for cell membranes. Thus, the adoption of the present concept would be beneficial for tailoring studies on plasma-treated cell-mimics. Finally, the liposome treatment is discussed with respect to possible physicochemical mechanisms and potential discharge modification due to the various compositions of the liquid electrode.

Effect of mixed γ-plus neutron-radiation on permeability to taurine of peripheral blood leukocyte membranes

International Nuclear Information System (INIS)

Dokshina, G.A.; Naumenko, L.A.

1980-01-01

A study was made of permeability to taurine of cellular membranes of peripheral blood leukocytes in vitro under normal conditions and 24 k following mixed γ-plus neutron-irradiation in a dose of 3.5 Gy. It was established that radiation increases the taurine content of cells. The protein content of leukocytes also increases probably due to a better sorption of serum proteins of blood

Increasing the permeability of Escherichia coli using MAC13243

DEFF Research Database (Denmark)

Muheim, Claudio; Götzke, Hansjörg; Eriksson, Anna U.

2017-01-01

molecules that make the outer membrane of Escherichia coli more permeable. We identified MAC13243, an inhibitor of the periplasmic chaperone LolA that traffics lipoproteins from the inner to the outer membrane. We observed that cells were (1) more permeable to the fluorescent probe 1-N...

Do phosphoinositides regulate membrane water permeability of tobacco protoplasts by enhancing the aquaporin pathway?

Science.gov (United States)

Ma, Xiaohong; Shatil-Cohen, Arava; Ben-Dor, Shifra; Wigoda, Noa; Perera, Imara Y; Im, Yang Ju; Diminshtein, Sofia; Yu, Ling; Boss, Wendy F; Moshelion, Menachem; Moran, Nava

2015-03-01

Enhancing the membrane content of PtdInsP 2 , the already-recognized protein-regulating lipid, increased the osmotic water permeability of tobacco protoplasts, apparently by increasing the abundance of active aquaporins in their membranes. While phosphoinositides are implicated in cell volume changes and are known to regulate some ion channels, their modulation of aquaporins activity has not yet been reported for any organism. To examine this, we compared the osmotic water permeability (P f) of protoplasts isolated from tobacco (Nicotiana tabacum) cultured cells (NT1) with different (genetically lowered or elevated relative to controls) levels of inositol trisphosphate (InsP3) and phosphatidyl inositol [4,5] bisphosphate (PtdInsP2). To achieve this, the cells were transformed with, respectively, the human InsP3 5-phosphatase ('Ptase cells') or human phosphatidylinositol (4) phosphate 5-kinase ('PIPK cells'). The mean P f of the PIPK cells was several-fold higher relative to that of controls and Ptase cells. Three results favor aquaporins over the membrane matrix as underlying this excessive P f: (1) transient expression of the maize aquaporin ZmPIP2;4 in the PIPK cells increased P f by 12-30 μm s(-1), while in the controls only by 3-4 μm s(-1). (2) Cytosol acidification-known to inhibit aquaporins-lowered the P f in the PIPK cells down to control levels. (3) The transcript of at least one aquaporin was elevated in the PIPK cells. Together, the three results demonstrate the differences between the PIPK cells and their controls, and suggest a hitherto unobserved regulation of aquaporins by phosphoinositides, which could occur through direct interaction or indirect phosphoinositides-dependent cellular effects.

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.

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.

Investigation of endothelial growth using a sensors-integrated microfluidic system to simulate physiological barriers

Directory of Open Access Journals (Sweden)

Rajabi Taleieh

2015-09-01

Full Text Available In this paper we present a microfluidic system based on transparent biocompatible polymers with a porous membrane as substrate for various cell types which allows the simulation of various physiological barriers under continuous laminar flow conditions at distinct tunable shear rates. Besides live cell and fluorescence microscopy, integrated electrodes enable the investigation of the permeability and barrier function of the cell layer as well as their interaction with external manipulations using the Electric Cell-substrate Impedance Sensing (ECIS method.

Nafion–clay nanocomposite membranes: Morphology and properties

KAUST Repository

Herrera Alonso, Rafael; Estevez, Luis; Lian, Huiqin; Kelarakis, Antonios; Giannelis, Emmanuel P.

2009-01-01

A series of Nafion-clay nanocomposite membranes were synthesized and characterized. To minimize any adverse effects on ionic conductivity the clay nanoparticles were H+ exchanged prior to mixing with Nafion. Well-dispersed, mechanically robust, free-standing nanocomposite membranes were prepared by casting from a water suspension at 180 °C under pressure. SAXS profiles reveal a preferential orientation of Nafion aggregates parallel to the membrane surface, or normal plane. This preferred orientation is induced by the platy nature of the clay nanoparticles, which tend to align parallel to the surface of the membrane. The nanocomposite membranes show dramatically reduced methanol permeability, while maintaining high levels of proton conductivity. The hybrid films are much stiffer and can withstand much higher temperatures compared to pure Nafion. The superior thermomechanical, electrochemical and barrier properties of the nanocomposite membranes are of significant interest for direct methanol fuel cell applications. © 2009 Elsevier Ltd. All rights reserved.

Nafion–clay nanocomposite membranes: Morphology and properties

KAUST Repository

Herrera Alonso, Rafael

2009-05-01

A series of Nafion-clay nanocomposite membranes were synthesized and characterized. To minimize any adverse effects on ionic conductivity the clay nanoparticles were H+ exchanged prior to mixing with Nafion. Well-dispersed, mechanically robust, free-standing nanocomposite membranes were prepared by casting from a water suspension at 180 °C under pressure. SAXS profiles reveal a preferential orientation of Nafion aggregates parallel to the membrane surface, or normal plane. This preferred orientation is induced by the platy nature of the clay nanoparticles, which tend to align parallel to the surface of the membrane. The nanocomposite membranes show dramatically reduced methanol permeability, while maintaining high levels of proton conductivity. The hybrid films are much stiffer and can withstand much higher temperatures compared to pure Nafion. The superior thermomechanical, electrochemical and barrier properties of the nanocomposite membranes are of significant interest for direct methanol fuel cell applications. © 2009 Elsevier Ltd. All rights reserved.

Genetic Manipulation of Outer Membrane Permeability: Generating Porous Heterogeneous Catalyst Analogs in Escherichia coli

Energy Technology Data Exchange (ETDEWEB)

Patel, TN; Park, AHA; Bantat, S

2014-12-01

The limited permeability of the E. coli outer membrane can significantly hinder whole-cell biocatalyst performance. In this study, the SARS coronavirus small envelope protein (SCVE) was expressed in E. coli cells previously engineered for periplasmic expression of carbonic anhydrase (CA) activity. This maneuver increased small molecule uptake by the cells, resulting in increased apparent CA activity of the biocatalysts. The enhancements in activity were quantified using methods developed for traditional heterogeneous catalysis. The expression of the SCVE protein was found to significantly reduce the Thiele moduli (phi), as well as increase the effectiveness factors (eta), effective diffusivities (D-e), and permeabilities (P) of the biocatalysts. These catalytic improvements translated into superior performance of the biocatalysts for the precipitation of calcium carbonate from solution which is an attractive strategy for long-term sequestration of captured carbon dioxide. Overall, these results demonstrate that synthetic biology approaches can be used to enhance heterogeneous catalysts incorporated into microbial whole-cell scaffolds.

Prediction of Groundwater Quality Improvement Down-Gradient of In Situ Permeable Treatment Barriers and Fully-Remediated Source Zones. ESTCP Cost and Performance Report

National Research Council Canada - National Science Library

Johnson, Paul C; Carlson, Pamela M; Dahlen, Paul

2008-01-01

In situ permeable treatment barriers (PTB) are designed so that contaminated groundwater flows through an engineered treatment zone within which contaminants are eliminated or the concentrations are significantly reduced...

Permeable Reactive Barriers: a multidisciplinary approach of a new emerging sustainable groundwater treatment technology

Energy Technology Data Exchange (ETDEWEB)

Diels, L.; Bastiaens, L. [Vito, Mol (BL); O' Hannessin, S. [EnviroMetal Technologies Inc., Ontario (Canada); Cortina, J.L. [Univ. Politecnica de Catalunya, Barcelona (Spain). Dept. d' Enginyeria Quimica; Alvarez, P.J. [Univ. of Iowa, Iowa-City (United States). Center for Biocatalysis and Bioprocessing; Ebert, M. [Christian-Albrechts Univ. Kiel (Germany). Inst. fuer Geowissenschaften; Schad, H. [I.M.E.S. GmbH, Amtzell (Germany)

2003-07-01

Permeable reactive barriers or zones are becoming an interesting sustainable and cost-effective technology for in situ treatment of contaminated groundwater. The technology is based on chemical processes as the dehalogenating activity of zerovalent iron, biological processes in bioscreens or reactive zones and on sorption technology (e.g. heavy metal adsorption or adsorption on granular activated carbon). Three technical sessions will be devoted to this nowadays becoming mature technology. This special session intends to pay attention to the discussion about some questions related to PRBs. These include the sustainability (e.g. life time and clogging) especially for zerovalent iron barriers, the need and quality of feasibility tests, drawbacks and restrictions of PRBs. Combined with long term performance monitoring os these systems will be discussed. Further attention will be paid to cost evaluation and the relationship between zerovalent barriers and bacterial growth. Also attention will be paid to new reactive materials (e.g. activated carbon for organics and inorganic materials for heavy metals) and consequences (e.g. environmental impact). Finally the session will combine al these approaches in a discussion about combined barriers or multibarriers for treatment of mixed pollution (e.g. landfill leachates contaminated groundwater). Specialists involved in these subjects will introduce these topics and allow for a large and intensive discussion to improve future applications of this technology. (orig.)

Selective and membrane-permeable small molecule inhibitors of nicotinamide N-methyltransferase reverse high fat diet-induced obesity in mice.

Science.gov (United States)

Neelakantan, Harshini; Vance, Virginia; Wetzel, Michael D; Wang, Hua-Yu Leo; McHardy, Stanton F; Finnerty, Celeste C; Hommel, Jonathan D; Watowich, Stanley J

2018-01-01

There is a critical need for new mechanism-of-action drugs that reduce the burden of obesity and associated chronic metabolic comorbidities. A potentially novel target to treat obesity and type 2 diabetes is nicotinamide-N-methyltransferase (NNMT), a cytosolic enzyme with newly identified roles in cellular metabolism and energy homeostasis. To validate NNMT as an anti-obesity drug target, we investigated the permeability, selectivity, mechanistic, and physiological properties of a series of small molecule NNMT inhibitors. Membrane permeability of NNMT inhibitors was characterized using parallel artificial membrane permeability and Caco-2 cell assays. Selectivity was tested against structurally-related methyltransferases and nicotinamide adenine dinucleotide (NAD + ) salvage pathway enzymes. Effects of NNMT inhibitors on lipogenesis and intracellular levels of metabolites, including NNMT reaction product 1-methylnicotianamide (1-MNA) were evaluated in cultured adipocytes. Effects of a potent NNMT inhibitor on obesity measures and plasma lipid were assessed in diet-induced obese mice fed a high-fat diet. Methylquinolinium scaffolds with primary amine substitutions displayed high permeability from passive and active transport across membranes. Importantly, methylquinolinium analogues displayed high selectivity, not inhibiting related SAM-dependent methyltransferases or enzymes in the NAD + salvage pathway. NNMT inhibitors reduced intracellular 1-MNA, increased intracellular NAD + and S-(5'-adenosyl)-l-methionine (SAM), and suppressed lipogenesis in adipocytes. Treatment of diet-induced obese mice systemically with a potent NNMT inhibitor significantly reduced body weight and white adipose mass, decreased adipocyte size, and lowered plasma total cholesterol levels. Notably, administration of NNMT inhibitors did not impact total food intake nor produce any observable adverse effects. These results support development of small molecule NNMT inhibitors as therapeutics to

Correlation of Gas Permeability in a Metal-Organic Framework MIL-101(Cr)-Polysulfone Mixed-Matrix Membrane with Free Volume Measurements by Positron Annihilation Lifetime Spectroscopy (PALS).

Science.gov (United States)

Jeazet, Harold B Tanh; Koschine, Tönjes; Staudt, Claudia; Raetzke, Klaus; Janiak, Christoph

2013-10-25

Hydrothermally stable particles of the metal-organic framework MIL-101(Cr) were incorporated into a polysulfone (PSF) matrix to produce mixed-matrix or composite membranes with excellent dispersion of MIL-101 particles and good adhesion within the polymer matrix. Pure gas (O2, N2, CO2 and CH4) permeation tests showed a significant increase of gas permeabilities of the mixed-matrix membranes without any loss in selectivity. Positron annihilation lifetime spectroscopy (PALS) indicated that the increased gas permeability is due to the free volume in the PSF polymer and the added large free volume inside the MIL-101 particles. The trend of the gas transport properties of the composite membranes could be reproduced by a Maxwell model.

Blood-retinal barrier glycerol permeability in diabetic macular edema and healthy eyes: estimations from macular volume changes after peroral glycerol

DEFF Research Database (Denmark)

Thornit, Dorte Nellemann; Vinten, Carl Martin; Sander, Birgit

2010-01-01

PURPOSE: To compare the changes in macular volume (MV) between healthy subjects and patients with diabetic macular edema (DME) after an osmotic load and to determine the glycerol permeability (P(gly)) of the blood-retinal barrier (BRB). METHODS: In this unmasked study, 13 patients with DME and 5...

Subcompartmentalization by cross-membranes during early growth of Streptomyces hyphae

DEFF Research Database (Denmark)

Yagüe, Paula; Willemse, Joost; Koning, Roman I

2016-01-01

Bacteria of the genus Streptomyces are a model system for bacterial multicellularity. Their mycelial life style involves the formation of long multinucleated hyphae during vegetative growth, with occasional cross-walls separating long compartments. Reproduction occurs by specialized aerial hyphae......, which differentiate into chains of uninucleoid spores. While the tubulin-like FtsZ protein is required for the formation of all peptidoglycan-based septa in Streptomyces, canonical divisome-dependent cell division only occurs during sporulation. Here we report extensive subcompartmentalization in young...... vegetative hyphae of Streptomyces coelicolor, whereby 1 μm compartments are formed by nucleic acid stain-impermeable barriers. These barriers possess the permeability properties of membranes and at least some of them are cross-membranes without detectable peptidoglycan. Z-ladders form during the early growth...

NMR studies of human blood cells in health and disease. I. Alterations of the plasma membrane water permeability of erythrocytes

International Nuclear Information System (INIS)

Katona, Eva; Doaga, I. O.; Radulet, Diana; Caplanusi, A.; Negreanu, Cezarina; Mihele, Denisa

1999-01-01

Alterations in pathological cases of the human erythrocyte membrane water permeability were investigated by using a Mn 2+ -doping 1 H nuclear magnetic resonance (NMR) technique. The temperature dependence of the apparent water diffusional exchange through erythrocyte membranes in chronic hepatitis, diabetes, dyslipidemia and essential hypertension was measured and compared to healthy controls. Using moderate manganese concentrations (9-18 mM) and Carr-Purcell-Meiboom-Gill pulse sequences with a large number of refocusing π pulses and short interpulse delay (100 μs) our values of the water exchange times (τ e ) across erythrocyte membranes, obtained within a 10 min time period following the moment of doping, were independent of the actual manganese concentration and the Arrhenius plot for water exchange was linear over the range of 22-42 deg C. A marked increase of the water exchange times values was observed in all studied disease states. In case of chronic hepatitis, diabetes and dyslipidemia the changes observed in transmembrane water exchange time were associated with significant increase in the apparent activation energy of the diffusional water permeability thus, pointing out alterations in the function of the erythrocyte water channel. (author)

NMR studies of human blood cells in health and disease. I. Alterations of the plasma membrane water permeability of erythrocytes

Energy Technology Data Exchange (ETDEWEB)

Katona, Eva; Doaga, I O; Radulet, Diana [Department of Biophysics, Carol Davila University of Medicine and Pharmaceutics, 8 Blvd. Eroilor Sanitari, POB 15-205, RO-76241 Bucharest (Romania); Caplanusi, A [Medical Biochemistry Department, Carol Davila University of Medicine and Pharmaceutics, 8 Blvd. Eroilor Sanitari, POB 15-205, RO-76241 Bucharest (Romania); Negreanu, Cezarina [Division of New Energy Conversion Methods, Institute of Research and Design for Thermoenergetic Equipment, ICPET-CERCETARE, Bucharest (Romania); Mihele, Denisa [Clinical Laboratory Department, Carol Davila University of Medicine and Pharmaceutics, 8 Blvd. Eroilor Sanitari, POB 15-205, RO-76241 Bucharest (Romania)

1999-07-01

Alterations in pathological cases of the human erythrocyte membrane water permeability were investigated by using a Mn{sup 2+}-doping {sup 1}H nuclear magnetic resonance (NMR) technique. The temperature dependence of the apparent water diffusional exchange through erythrocyte membranes in chronic hepatitis, diabetes, dyslipidemia and essential hypertension was measured and compared to healthy controls. Using moderate manganese concentrations (9-18 mM) and Carr-Purcell-Meiboom-Gill pulse sequences with a large number of refocusing {pi} pulses and short interpulse delay (100 {mu}s) our values of the water exchange times ({tau}{sub e}) across erythrocyte membranes, obtained within a 10 min time period following the moment of doping, were independent of the actual manganese concentration and the Arrhenius plot for water exchange was linear over the range of 22-42 deg C. A marked increase of the water exchange times values was observed in all studied disease states. In case of chronic hepatitis, diabetes and dyslipidemia the changes observed in transmembrane water exchange time were associated with significant increase in the apparent activation energy of the diffusional water permeability thus, pointing out alterations in the function of the erythrocyte water channel. (author)

Recovery of ammonia from anaerobically digested manure using gas-permeable membranes

Directory of Open Access Journals (Sweden)

Maria Cruz García-González

Full Text Available ABSTRACT Nitrogen (N can be recovered from different types of wastewaters. Among these wastewaters, anaerobically digested swine manure (digestate has the highest N content in ammonia form (NH3. It is desirable to reduce N in digestate effluents to safely incorporate them in arable soil in N vulnerable zones (NVZ and to mitigate NH3 emissions during N land application. Additional benefit is to minimize inhibition of the anaerobic process by removing NH3 during the anaerobic digestion process. This work aimed to apply the gas-permeable membrane technology to evaluate ammonia (NH3 recovery from high-ammonia digested swine manure. Anaerobically digested swine manure with NH4+ content of 4,293 mg N L−1 was reduced by 91 % (to 381 mg N L−1 during the 32-day experiment. Although the results showed a total N recovery efficiency of 71 %, it is possible to increase this recovery efficiency to > 90 % by adjusting the area of the membrane system to match the high free ammonia concentration (FA in digested swine manure. Moreover, final digestate pH and alkalinity were kept around 8.1 and 8,923 mgCaCO3 L−1, which are convenient for the anaerobic process or incorporation in arable soil when the process is finished.

Permeable reactive barrier of surface hydrophobic granular activated carbon coupled with elemental iron for the removal of 2,4-dichlorophenol in water

Energy Technology Data Exchange (ETDEWEB)

Yang Ji, E-mail: yangji@ecust.edu.cn [School of Resources and Environmental Engineering, State Environmental Protection Key Laboratory of Environmental Risk Assessment and Control on Chemical Process, East China University of Science and Technology, Shanghai 200237 (China); Cao Limei; Guo Rui; Jia Jinping [School of Environmental Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240 (China)

2010-12-15

Granular activated carbon was modified with dimethyl dichlorosilane to improve its surface hydrophobicity, and therefore to improve the performance of permeable reactive barrier constructed with the modified granular activated carbon and elemental iron. X-ray photoelectron spectroscopy shows that the surface silicon concentration of the modified granular activated carbon is higher than that of the original one, leading to the increased surface hydrophobicity. Although the specific surface area decreased from 895 to 835 m{sup 2} g{sup -1}, the modified granular activated carbon could adsorb 20% more 2,4-dichlorophenol than the original one did in water. It is also proven that the permeable reactive barrier with the modified granular activated carbon is more efficient at 2,4-dichlorophenol dechlorination, in which process 2,4-dichlorophenol is transformed to 2-chlorophenol or 4-chlorophenol then to phenol, or to phenol directly.

Permeable reactive barrier of surface hydrophobic granular activated carbon coupled with elemental iron for the removal of 2,4-dichlorophenol in water

International Nuclear Information System (INIS)

Yang Ji; Cao Limei; Guo Rui; Jia Jinping

2010-01-01

Granular activated carbon was modified with dimethyl dichlorosilane to improve its surface hydrophobicity, and therefore to improve the performance of permeable reactive barrier constructed with the modified granular activated carbon and elemental iron. X-ray photoelectron spectroscopy shows that the surface silicon concentration of the modified granular activated carbon is higher than that of the original one, leading to the increased surface hydrophobicity. Although the specific surface area decreased from 895 to 835 m 2 g -1 , the modified granular activated carbon could adsorb 20% more 2,4-dichlorophenol than the original one did in water. It is also proven that the permeable reactive barrier with the modified granular activated carbon is more efficient at 2,4-dichlorophenol dechlorination, in which process 2,4-dichlorophenol is transformed to 2-chlorophenol or 4-chlorophenol then to phenol, or to phenol directly.

Tri-membrane nanoparticles produced by combining liposome fusion and a novel patchwork of bicelles to overcome endosomal and nuclear membrane barriers to cargo delivery.

Science.gov (United States)

Yamada, Asako; Mitsueda, Asako; Hasan, Mahadi; Ueda, Miho; Hama, Susumu; Warashina, Shota; Nakamura, Takashi; Harashima, Hideyoshi; Kogure, Kentaro

2016-03-01

Membrane fusion is a rational strategy for crossing intracellular membranes that present barriers to liposomal nanocarrier-mediated delivery of plasmid DNA into the nucleus of non-dividing cells, such as dendritic cells. Based on this strategy, we previously developed nanocarriers consisting of a nucleic acid core particle coated with four lipid membranes [Akita, et al., Biomaterials, 2009, 30, 2940-2949]. However, including the endosomal membrane and two nuclear membranes, cells possess three intracellular membranous barriers. Thus, after entering the nucleus, nanoparticles coated with four membranes would still have one lipid membrane remaining, and could impede cargo delivery. Until now, coating a core particle with an odd number of lipid membranes was challenging. To produce nanocarriers with an odd number of lipid membranes, we developed a novel coating method involving lipid nano-discs, also known as bicelles, as a material for packaging DNA in a carrier with an odd number of lipid membranes. In this procedure, bicelles fuse to form an outer coating that resembles a patchwork quilt, which allows the preparation of nanoparticles coated with only three lipid membranes. Moreover, the transfection activity of dendritic cells with these three-membrane nanoparticles was higher than that for nanoparticles coated with four lipid membranes. In summary, we developed novel nanoparticles coated with an odd number of lipid membranes using the novel "patchwork-packaging method" to deliver plasmid DNA into the nucleus via membrane fusion.

Oxidation of volatile organic compound vapours by potassium permanganate in a horizontal permeable reactive barrier under unsaturated conditions: experiments and modeling

NARCIS (Netherlands)

Ghareh Mahmoodlu, Mojtaba|info:eu-repo/dai/nl/357287746

2014-01-01

In this research we evaluated the potential of using solid potassium permanganate to create a horizontal permeable reactive barrier (HPRB) for oxidizing VOC vapours in the unsaturated zone. We have performed batch experiments, short column, and long column experiments, and have fully analyzed the

Hydrogen purifier module with membrane support

Science.gov (United States)

A hydrogen purifier utilizing a hydrogen-permeable membrane to purify hydrogen from mixed gases containing hydrogen is disclosed. Improved mechanical support for the permeable membrane is described, enabling forward or reverse differential pressurization of the membrane, which further stabilizes the membrane from wrinkling upon hydrogen uptake.

2012-07-24

A hydrogen purifier utilizing a hydrogen-permeable membrane to purify hydrogen from mixed gases containing hydrogen is disclosed. Improved mechanical support for the permeable membrane is described, enabling forward or reverse differential pressurization of the membrane, which further stabilizes the membrane from wrinkling upon hydrogen uptake.

Synthesis of ceramic hollow fiber supported zeolitic imidazolate framework-8 (ZIF-8) membranes with high hydrogen permeability

KAUST Repository

Pan, Yichang; Wang, Bo; Lai, Zhiping

2012-01-01

Purification and recovery of hydrogen from hydrocarbons in refinery streams in the petrochemical industry is an emerging research field in the study of membrane gas separation. Hollow fiber membrane modules can be easily implemented into separation processes at the industrial scale. In this report, hollow yttria-stabilized zirconia (YSZ) fiber-supported zeolitic imidazole framework-8 (ZIF-8) membranes were successfully prepared using a mild and environmentally friendly seeded growth method. Our single-component permeation studies demonstrated that the membrane had a very high hydrogen permeance (~15×10 -7mol/m 2sPa) and an ideal selectivity of H 2/C 3H 8 of more than 1000 at room temperature. This high membrane permeability and selectivity caused serious concentration polarization in the separation of H 2/C 3H 8 mixtures, which led to almost 50% drop in both the H 2 permeance and the separation factor. Enhanced mixing on the feed side could reduce the effect of the concentration polarization. Our experimental data also indicated that the membranes had excellent reproducibility and long-term stability, indicating that the hollow fiber-supported ZIF-8 membranes developed in this study have great potential in industry-scale separation of hydrogen. © 2012 Elsevier B.V.

Synthesis of ceramic hollow fiber supported zeolitic imidazolate framework-8 (ZIF-8) membranes with high hydrogen permeability

KAUST Repository

Pan, Yichang

2012-12-01

Purification and recovery of hydrogen from hydrocarbons in refinery streams in the petrochemical industry is an emerging research field in the study of membrane gas separation. Hollow fiber membrane modules can be easily implemented into separation processes at the industrial scale. In this report, hollow yttria-stabilized zirconia (YSZ) fiber-supported zeolitic imidazole framework-8 (ZIF-8) membranes were successfully prepared using a mild and environmentally friendly seeded growth method. Our single-component permeation studies demonstrated that the membrane had a very high hydrogen permeance (~15×10 -7mol/m 2sPa) and an ideal selectivity of H 2/C 3H 8 of more than 1000 at room temperature. This high membrane permeability and selectivity caused serious concentration polarization in the separation of H 2/C 3H 8 mixtures, which led to almost 50% drop in both the H 2 permeance and the separation factor. Enhanced mixing on the feed side could reduce the effect of the concentration polarization. Our experimental data also indicated that the membranes had excellent reproducibility and long-term stability, indicating that the hollow fiber-supported ZIF-8 membranes developed in this study have great potential in industry-scale separation of hydrogen. © 2012 Elsevier B.V.

Lipids in the Assembly of Membrane Proteins and Organization of Protein Supercomplexes: Implications for Lipid-Linked Disorders

OpenAIRE

Bogdanov, Mikhail; Mileykovskaya, Eugenia; Dowhan, William

2008-01-01

Lipids play important roles in cellular dysfunction leading to disease. Although a major role for phospholipids is in defining the membrane permeability barrier, phospholipids play a central role in a diverse range of cellular processes and therefore are important factors in cellular dysfunction and disease. This review is focused on the role of phospholipids in normal assembly and organization of the membrane proteins, multimeric protein complexes, and higher order supercomplexes. Since lipi...

Permeability and Diffusion Coefficients of Single Methyl Lactate Enantiomers in Nafion® and Cellophane Membranes Measured in Diffusion Cell.

Czech Academy of Sciences Publication Activity Database

Hovorka, Š.; Randová, A.; Borbášová, T.; Sysel, P.; Vychodilová, Hana; Červenková Šťastná, Lucie; Brožová, Libuše; Žitka, Jan; Storch, Jan; Kačírková, Marie; Drašar, P.; Izák, Pavel

2016-01-01

Roč. 158, JAN 28 (2016), s. 322-332 ISSN 1383-5866 R&D Projects: GA ČR(CZ) GAP106/12/0569 Institutional support: RVO:67985858 ; RVO:61389013 Keywords : diffusion coefficient measurement * permeability * nafion * cellophane * chirality of polymer membrane Subject RIV: CI - Industrial Chemistry, Chemical Engineering Impact factor: 3.359, year: 2016

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.

Improved Prediction of Blood-Brain Barrier Permeability Through Machine Learning with Combined Use of Molecular Property-Based Descriptors and Fingerprints.

Science.gov (United States)

Yuan, Yaxia; Zheng, Fang; Zhan, Chang-Guo

2018-03-21

Blood-brain barrier (BBB) permeability of a compound determines whether the compound can effectively enter the brain. It is an essential property which must be accounted for in drug discovery with a target in the brain. Several computational methods have been used to predict the BBB permeability. In particular, support vector machine (SVM), which is a kernel-based machine learning method, has been used popularly in this field. For SVM training and prediction, the compounds are characterized by molecular descriptors. Some SVM models were based on the use of molecular property-based descriptors (including 1D, 2D, and 3D descriptors) or fragment-based descriptors (known as the fingerprints of a molecule). The selection of descriptors is critical for the performance of a SVM model. In this study, we aimed to develop a generally applicable new SVM model by combining all of the features of the molecular property-based descriptors and fingerprints to improve the accuracy for the BBB permeability prediction. The results indicate that our SVM model has improved accuracy compared to the currently available models of the BBB permeability prediction.

Differential protection by cell wall components of Lactobacillus amylovorus DSM 16698Tagainst alterations of membrane barrier and NF-kB activation induced by enterotoxigenic F4+ Escherichia coli on intestinal cells.

Science.gov (United States)

Roselli, Marianna; Finamore, Alberto; Hynönen, Ulla; Palva, Airi; Mengheri, Elena

2016-09-29

The role of Lactobacillus cell wall components in the protection against pathogen infection in the gut is still largely unexplored. We have previously shown that L. amylovorus DSM 16698 T is able to reduce the enterotoxigenic F4 + Escherichia coli (ETEC) adhesion and prevent the pathogen-induced membrane barrier disruption through the regulation of IL-10 and IL-8 expression in intestinal cells. We have also demonstrated that L. amylovorus DSM 16698 T protects host cells through the inhibition of NF-kB signaling. In the present study, we investigated the role of L. amylovorus DSM 16698 T cell wall components in the protection against F4 + ETEC infection using the intestinal Caco-2 cell line. Purified cell wall fragments (CWF) from L. amylovorus DSM 16698 T were used either as such (uncoated, U-CWF) or coated with S-layer proteins (S-CWF). Differentiated Caco-2/TC7 cells on Transwell filters were infected with F4 + ETEC, treated with S-CWF or U-CWF, co-treated with S-CWF or U-CWF and F4 + ETEC for 2.5 h, or pre-treated with S-CWF or U-CWF for 1 h before F4 + ETEC addition. Tight junction (TJ) and adherens junction (AJ) proteins were analyzed by immunofluorescence and Western blot. Membrane permeability was determined by phenol red passage. Phosphorylated p65-NF-kB was measured by Western blot. We showed that both the pre-treatment with S-CWF and the co- treatment of S-CWF with the pathogen protected the cells from F4 + ETEC induced TJ and AJ injury, increased membrane permeability and activation of NF-kB expression. Moreover, the U-CWF pre-treatment, but not the co-treatment with F4 + ETEC, inhibited membrane damage and prevented NF-kB activation. The results indicate that the various components of L. amylovorus DSM 16698 T cell wall may counteract the damage caused by F4 + ETEC through different mechanisms. S-layer proteins are essential for maintaining membrane barrier function and for mounting an anti-inflammatory response against F4 + ETEC infection. U-CWF are

Combining Nitrilotriacetic Acid and Permeable Barriers for Enhanced Phytoextraction of Heavy Metals from Municipal Solid Waste Compost by and Reduced Metal Leaching.

Science.gov (United States)

Zhao, Shulan; Jia, Lina; Duo, Lian

2016-05-01

Phytoextraction has the potential to remove heavy metals from contaminated soil, and chelants can be used to improve the capabilities of phytoextraction. However, environmentally persistent chelants can cause metal leaching and groundwater pollution. A column experiment was conducted to evaluate the viability of biodegradable nitrilotriacetic acid (NTA) to increase the uptake of heavy metals (Cd, Cr, Ni, Pb, Cu, and Zn) by L. in municipal solid waste (MSW) compost and to evaluate the effect of two permeable barrier materials, bone meal and crab shell, on metal leaching. The application of NTA significantly increased the concentrations and uptake of heavy metals in . The enhancement was more pronounced at higher dosages of NTA. In the 15 mmol kg NTA treatment using a crab shell barrier, the Cr and Ni concentrations in the plant shoots increased by approximately 8- and 10-fold, respectively, relative to the control. However, the addition of NTA also caused significant heavy metal leaching from the MSW compost. Bone meal and crab shell barriers positioned between the compost and the subsoil were effective in preventing metal leaching down through the soil profile by the retention of metals in the barrier. The application of a biodegradable chelant and the use of permeable barriers is a viable form of enhanced phytoextraction to increase the removal of metals and to reduce possible leaching. Copyright © by the American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America, Inc.

Transdermal therapeutic system of narcotic analgesics using nonporous membrane (I) : Effect of the ethanol permeability on vinylacetate content of EVA membrane

Energy Technology Data Exchange (ETDEWEB)

Kwon, H.; Song, H.Y. [Chungnam National University, Taejon (Korea); Khang, G.S. [Chonbuk National University, Chonju (Korea); Lee, H.B. [Korea Research Institute of Chemical Technology, Taejon (Korea)

1999-05-01

The fundamental properties of transdermal therapeutic patch as narcotic analgesics agent has been investigated. From the study of drug and ethanol release patterns from the fentanyl base (FB) patches through diffusion cell and hairless mouse skin, it was observed that the FB release patterns were largely affected by the content of vinyl acetate (VA) of ethylene-co-vinyl acetate (EVA) membrane, and volume fraction of ethanolic solution. Additionally, a variety of control membrane as a function of VA content were examined for swelling following equilibration with ethanolic solutions. Generally, ethanol was incorporated into a transdermal therapeutic device to enable the controlled delivery of enhancer and drug to the skin surface. In vitro skin permeation analysis of the control membrane showed that ethanol flux was linearly related to the ethanol volume fraction. This result was shown that drug permeability increased with increasing as the content of VA. But, the FB flux from saturated aqueous ethanol solutions increases until 80% ethanol volume fraction. Over 80% ethanol volume fraction, the FB flux through skin samples is independent of ethanol volume. These results showed that the decrease in skin permeation due to dehydration nis the dominant effect. 26 refs., 8 figs.

Advances in immobilized artificial membrane (IAM) chromatography for novel drug discovery.

Science.gov (United States)

Tsopelas, Fotios; Vallianatou, Theodosia; Tsantili-Kakoulidou, Anna

2016-01-01

The development of immobilized artificial membrane (IAM) chromatography has unfolded new perspectives for the use of chromatographic techniques in drug discovery, combining simulation of the environment of cell membranes with rapid measurements. The present review describes the characteristics of phosphatidylcholine-based stationary phases and analyses the molecular factors governing IAM retention in comparison to n-octanol-water and liposomes partitioning systems as well as to reversed phase chromatography. Other biomimetic stationary phases are also briefly discussed. The potential of IAM chromatography to model permeability through the main physiological barriers and drug membrane interactions is outlined. Further applications to calculate complex pharmacokinetic properties, related to tissue binding, and to screen drug candidates for phospholipidosis, as well as to estimate cell accumulation/retention are surveyed. The ambivalent nature of IAM chromatography, as a border case between passive diffusion and binding, defines its multiple potential applications. However, despite its successful performance in many permeability and drug-membrane interactions studies, IAM chromatography is still used as a supportive and not a stand-alone technique. Further studies looking at IAM chromatography in different biological processes are still required if this technique is to have a more focused and consistent application in drug discovery.

Nanoporous Membrane Technologies for Pathogen Collection, Separation, and Detection

National Research Council Canada - National Science Library

Lee, Sang W; Shang, Hao; Lee, Gil U; Griffin, Matthew T; Fulton, Jack

2003-01-01

Partial contents: Nanoporous Membranes, Membrane Chemistries, Characterization of Membrane Chemistries,Protein Fouling, Collector,Gas and Liquid Permeabilities, Membrane Permeabilities in the Presence of Water...

Delayed astrocytic contact with cerebral blood vessels in FGF-2 deficient mice does not compromise permeability properties at the developing blood-brain barrier.

Science.gov (United States)

Saunders, Norman R; Dziegielewska, Katarzyna M; Unsicker, Klaus; Ek, C Joakim

2016-11-01

The brain functions within a specialized environment tightly controlled by brain barrier mechanisms. Understanding the regulation of barrier formation is important for understanding brain development and may also lead to finding new ways to deliver pharmacotherapies to the brain; access of many potentially promising drugs is severely hindered by these barrier mechanisms. The cellular composition of the neurovascular unit of the blood-brain barrier proper and their effects on regulation of its function are beginning to be understood. One hallmark of the neurovascular unit in the adult is the astroglial foot processes that tightly surround cerebral blood vessels. However their role in barrier formation is still unclear. In this study we examined barrier function in newborn, juvenile and adult mice lacking fibroblast growth factor-2 (FGF-2), which has been shown to result in altered astroglial differentiation during development. We show that during development of FGF-2 deficient mice the astroglial contacts with cerebral blood vessels are delayed compared with wild-type animals. However, this delay did not result in changes to the permeability properties of the blood brain barrier as assessed by exclusion of either small or larger sized molecules at this interface. In addition cerebral vessels were positive for tight-junction proteins and we observed no difference in the ultrastructure of the tight-junctions. The results indicate that the direct contact of astroglia processes to cerebral blood vessels is not necessary for either the formation of the tight-junctions or for basic permeability properties and function of the blood-brain barrier. © 2016 Wiley Periodicals, Inc. Develop Neurobiol 76: 1201-1212, 2016. © 2016 Wiley Periodicals, Inc.

Influence of blood-brain barrier permeability on O-(2-{sup 18}F-fluoroethyl)-L-tyrosine uptake in rat gliomas

Energy Technology Data Exchange (ETDEWEB)

Stegmayr, Carina; Bandelow, Ulrike; Oliveira, Dennis; Lohmann, Philipp; Willuweit, Antje; Galldiks, Norbert; Luebke, Joachim H.R. [Institute of Neuroscience and Medicine, Forschungszentrum Juelich, Juelich (Germany); Filss, Christian; Ermert, Johannes; Langen, Karl-Josef [Institute of Neuroscience and Medicine, Forschungszentrum Juelich, Juelich (Germany); RWTH/University Hospital Aachen, Department of Nuclear Medicine and Neurology, Aachen (Germany); Shah, N. Jon [Institute of Neuroscience and Medicine, Forschungszentrum Juelich, Juelich (Germany); RWTH/University Hospital Aachen, Department of Nuclear Medicine and Neurology, Aachen (Germany); Juelich-Aachen Research Alliance (JARA) - Section JARA-Brain, Aachen (Germany)

2017-03-15

O-(2-{sup 18}F-fluoroethyl)-L-tyrosine ({sup 18}F-FET) is an established tracer for the diagnosis of brain tumors with PET. This study investigates the influence of blood-brain barrier (BBB) permeability on {sup 18}F-FET uptake in two rat glioma models and one human xenograft model. F98 glioma, 9L gliosarcoma or human U87 glioblastoma cells were implanted into the striatum of 56 Fischer or RNU rats. Thereafter, animals were divided into a control group and a group receiving injections of the glucocorticoid dexamethasone (Dex). After 12-13 days of tumor growth animals received injection of Evans blue dye (EBD) to visualize BBB disturbance and underwent {sup 18}F-FET PET followed by autoradiography. Time activity curves, standardized uptake values (SUV) and Tumor-to-brain ratios (TBR) of {sup 18}F-FET uptake [18-61 min post injection (p.i.)] were evaluated using a volume-of-Interest (VOI) analysis. BBB disturbance was quantitatively evaluated by EBD fluorescence. The membrane gaps of blood vessel endothelial tight junctions were measured using electron microscopy to visualize ultrastructural BBB alterations in one untreated and one Dex treated F98 glioma. Data were analyzed by two-way ANOVAs. In Dex treated animals EBD extravasation was significantly reduced in 9L (P < 0.001) and U87 (P = 0.008) models and showed a trend in F98 models (P = 0.053). In contrast, no significant differences of {sup 18}F-FET uptake were observed between Dex treated animals and control group except a decrease of the TBR in the 9L tumor model in PET (P < 0.01). Ultrastructural evaluation of tumor blood vessel endothelia revealed significant reduction of the cleft diameter between endothelial cells after Dex treatment in F98 model (P = 0.010). Despite a considerable reduction of BBB permeability in rat gliomas after Dex treatment, no relevant changes of {sup 18}F-FET uptake were noted in this experimental study. Thus, {sup 18}F-FET uptake in gliomas appears to be widely independent of the

Permeable reactive barrier of surface hydrophobic granular activated carbon coupled with elemental iron for the removal of 2,4-dichlorophenol in water.

Science.gov (United States)

Yang, Ji; Cao, Limei; Guo, Rui; Jia, Jinping

2010-12-15

Granular activated carbon was modified with dimethyl dichlorosilane to improve its surface hydrophobicity, and therefore to improve the performance of permeable reactive barrier constructed with the modified granular activated carbon and elemental iron. X-ray photoelectron spectroscopy shows that the surface silicon concentration of the modified granular activated carbon is higher than that of the original one, leading to the increased surface hydrophobicity. Although the specific surface area decreased from 895 to 835 m(2)g(-1), the modified granular activated carbon could adsorb 20% more 2,4-dichlorophenol than the original one did in water. It is also proven that the permeable reactive barrier with the modified granular activated carbon is more efficient at 2,4-dichlorophenol dechlorination, in which process 2,4-dichlorophenol is transformed to 2-chlorophenol or 4-chlorophenol then to phenol, or to phenol directly. Copyright © 2010 Elsevier B.V. All rights reserved.

A calcite permeable reactive barrier for the remediation of Fluoride from spent potliner (SPL) contaminated groundwater

DEFF Research Database (Denmark)

Turner, B.D.; Binning, Philip John; Sloan, S.W.

2008-01-01

The use of calcite (CaCO3) as a substrate for a permeable reactive barrier (PRB) for removing fluoride from contaminated groundwater is proposed and is illustrated by application to groundwater contaminated by spent potliner leachate (SPL), a waste derived from the aluminium smelting process...... leachate indicate that the complex chemical matrix of the SPL leachate can impact fluoride removal significantly. For SPL contaminant mixtures, fluoride removal is initially less than expected from idealized, pure, solutions. However, with time, the effect of other contaminants on fluoride removal...... diminishes. Column tests also show that pH control is important for optimizing fluoride removal with the mass removed increasing with decreasing pH. Barrier pH can be regulated by CO2 addition with the point of injection being critical for optimising the remediation performance. Experimental and model...

Processes And Apparatus For Inhibiting Membrane Bio-fouling

KAUST Repository

Missimer, Thomas M.

2012-12-20

Certain embodiments are directed to a process and apparatus for cleaning and/or regeneration of permeable or semipermeable membranes comprising modulating pressure of a feed stream feeding the permeable or semipermeable membrane and providing intermittent pressure pulses for cleaning and/or regeneration of the permeable or semipermeable membrane.

Processes And Apparatus For Inhibiting Membrane Bio-fouling

KAUST Repository

Missimer, Thomas M.; Ng, Kim Choon; Amy, Gary

2012-01-01

Certain embodiments are directed to a process and apparatus for cleaning and/or regeneration of permeable or semipermeable membranes comprising modulating pressure of a feed stream feeding the permeable or semipermeable membrane and providing intermittent pressure pulses for cleaning and/or regeneration of the permeable or semipermeable membrane.

Integrin-based diffusion barrier separates membrane domains enabling the formation of microbiostatic frustrated phagosomes

Science.gov (United States)

Maxson, Michelle E; Naj, Xenia; O'Meara, Teresa R; Plumb, Jonathan D; Cowen, Leah E

2018-01-01

Candida albicans hyphae can reach enormous lengths, precluding their internalization by phagocytes. Nevertheless, macrophages engulf a portion of the hypha, generating incompletely sealed tubular phagosomes. These frustrated phagosomes are stabilized by a thick cuff of F-actin that polymerizes in response to non-canonical activation of integrins by fungal glycan. Despite their continuity, the surface and invaginating phagosomal membranes retain a strikingly distinct lipid composition. PtdIns(4,5)P2 is present at the plasmalemma but is not detectable in the phagosomal membrane, while PtdIns(3)P and PtdIns(3,4,5)P3 co-exist in the phagosomes yet are absent from the surface membrane. Moreover, endo-lysosomal proteins are present only in the phagosomal membrane. Fluorescence recovery after photobleaching revealed the presence of a diffusion barrier that maintains the identity of the open tubular phagosome separate from the plasmalemma. Formation of this barrier depends on Syk, Pyk2/Fak and formin-dependent actin assembly. Antimicrobial mechanisms can thereby be deployed, limiting the growth of the hyphae. PMID:29553370

Correlation of Gas Permeability in a Metal-Organic Framework MIL-101(Cr)–Polysulfone Mixed-Matrix Membrane with Free Volume Measurements by Positron Annihilation Lifetime Spectroscopy (PALS)

Science.gov (United States)

Jeazet, Harold B. Tanh; Koschine, Tönjes; Staudt, Claudia; Raetzke, Klaus; Janiak, Christoph

2013-01-01

Hydrothermally stable particles of the metal-organic framework MIL-101(Cr) were incorporated into a polysulfone (PSF) matrix to produce mixed-matrix or composite membranes with excellent dispersion of MIL-101 particles and good adhesion within the polymer matrix. Pure gas (O2, N2, CO2 and CH4) permeation tests showed a significant increase of gas permeabilities of the mixed-matrix membranes without any loss in selectivity. Positron annihilation lifetime spectroscopy (PALS) indicated that the increased gas permeability is due to the free volume in the PSF polymer and the added large free volume inside the MIL-101 particles. The trend of the gas transport properties of the composite membranes could be reproduced by a Maxwell model. PMID:24957061

On the methanol permeability through pristine Nafion {sup registered} and Nafion/PVA membranes measured by different techniques. A comparison of methodologies

Energy Technology Data Exchange (ETDEWEB)

Molla, S.; Compan, V. [Departmento de Termodinamica Aplicada, Escuela de Ingenieria Tecnica Industrial (ETSII), Universidad Politecnica de Valencia, 46022 Valencia (Spain); Instituto Tecnologico de la Energia (ITE), Av. Juan de la Cierva 24, 46980 Paterna, Valencia (Spain); Luis Lafuente, S. [Departmento de Quimica Organica, Universidad Jaume I, 12072 Castellon (Spain); Prats, J. [Departmento de Termodinamica Aplicada, Escuela de Ingenieria Tecnica Industrial (ETSII), Universidad Politecnica de Valencia, 46022 Valencia (Spain)

2011-12-15

Methanol crossover through polymer electrolyte membranes is a critical issue and causes an important reduction of performance in direct methanol fuel cells (DMFCs). Measuring the evolution of CO{sub 2} gas in the cathode is a common method to determine the methanol crossover under real operating conditions, although an easier and simpler method is preferable for the screening of membranes during their step of development. In this sense, this work has been focused on the ex situ characterization of the methanol permeability in novel nanofiber-reinforced composite Nafion/PVA membranes for DMFC application by means of three different experimental procedures: (a) potentiometric method, (b) gas chromatography technique, and (c) measuring the density. It was found that all these methods resulted in comparable results and it was observed that the incorporation of the PVA nanofiber phase within the Nafion {sup registered} matrix causes a remarkable reduction of the methanol permeability. The optimal choice of the most suitable technique depends on the accuracy expected for the methanol concentration, the availability of the required instrumental, and the complexity of the procedure. (Copyright copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

Role of different biodegradable polymers on the permeability of ciprofloxacin

Directory of Open Access Journals (Sweden)

Chandra Kanti Chakraborti

2014-01-01

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

A technique to investigate the mechanism of uniform corrosion in the presence of a semi-permeable membrane

International Nuclear Information System (INIS)

King, F.

1987-01-01

A technique to investigate the mechanism of uniform corrosion in the presence of a semi-permeable membrane is described. For both the anodic and cathodic half-reactions three possible rate-determining steps are considered: transport of species through the bulk solution diffusion layer, transport of species through the membrane and the electrochemical reaction itself. The technique is based on the measurement of the corrosion potential, E CORR , of a rotating disc electrode under steady-state conditions. The variation of E CORR with the oxidant concentration, the thickness of the diffusion layer and the membrane thickness is used to identify the rate-determining step for each half-reaction. This technique should be of use in the study of the corrosion behaviour of candidate materials for nuclear waste disposal containers. An understanding of the mechanism of uniform corrosion will enable confident predictions to be made concerning the long-term behaviour of such containers

In vitro evaluation of various bioabsorbable and nonresorbable barrier membranes for guided tissue regeneration

Directory of Open Access Journals (Sweden)

Smeets Ralf

2008-10-01

Full Text Available Abstract Background Different types of bioabsorbable and nonresorbable membranes have been widely used for guided tissue regeneration (GTR with its ultimate goal of regenerating lost periodontal structures. The purpose of the present study was to evaluate the biological effects of various bioabsorbable and nonresorbable membranes in cultures of primary human gingival fibroblasts (HGF, periodontal ligament fibroblasts (PDLF and human osteoblast-like (HOB cells in vitro. Methods Three commercially available collagen membranes [TutoDent® (TD, Resodont® (RD and BioGide® (BG] as well as three nonresorbable polytetrafluoroethylene (PTFE membranes [ACE (AC, Cytoplast® (CT and TefGen-FD® (TG] were tested. Cells plated on culture dishes (CD served as positive controls. The effect of the barrier membranes on HGF, PDLF as well as HOB cells was assessed by the Alamar Blue fluorometric proliferation assay after 1, 2.5, 4, 24 and 48 h time periods. The structural and morphological properties of the membranes were evaluated by scanning electron microscopy (SEM. Results The results showed that of the six barriers tested, TD and RD demonstrated the highest rate of HGF proliferation at both earlier (1 h and later (48 h time periods (P P ≤ 0.001. In HOB cell culture, the highest rate of cell proliferation was also calculated for TD at all time periods (P Conclusion Results from the present study suggested that GTR membrane materials, per se, may influence cell proliferation in the process of periodontal tissue/bone regeneration. Among the six membranes examined, the bioabsorbable membranes demonstrated to be more suitable to stimulate cellular proliferation compared to nonresorbable PTFE membranes.

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

Water transport and desalination through double-layer graphyne membranes.

Science.gov (United States)

Akhavan, Mojdeh; Schofield, Jeremy; Jalili, Seifollah

2018-05-16

Non-equilibrium molecular dynamics simulations of water-salt solutions driven through single and double-layer graphyne membranes by a pressure difference created by rigid pistons are carried out to determine the relative performance of the membranes as filters in a reverse osmosis desalination process. It is found that the flow rate of water through a graphyne-4 membrane is twice that of a graphyne-3 membrane for both single and double-layer membranes. Although the addition of a second layer to a single-layer membrane reduces the membrane permeability, the double-layer graphyne membranes are still two or three orders of magnitude more permeable than commercial reverse osmosis membranes. The minimum reduction in flow rate for double-layer membranes occurs at a layer spacing of 0.35 nm with an AA stacking configuration, while at a spacing of 0.6 nm the flow rate is close to zero due to a high free energy barrier for permeation. This is caused by the difference in the environments on either side of the membrane sheets and the formation of a compact two-dimensional layer of water molecules in the interlayer space which slows down water permeation. The distribution of residence times of water molecules in the interlayer region suggests that at the critical layer spacing of 0.6 nm, a cross-over occurs in the mechanism of water flow from the collective movement of hydrogen-bonded water sheets to the permeation of individual water molecules. All membranes are demonstrated to have a high salt rejection fraction and the double-layered graphyne-4 membranes can further increase the salt rejection by trapping ions that have passed through the first membrane from the feed solution in the interlayer space.

Pharmacological aspects of release from microcapsules - from polymeric multilayers to lipid membranes.

Science.gov (United States)

Wuytens, Pieter; Parakhonskiy, Bogdan; Yashchenok, Alexey; Winterhalter, Mathias; Skirtach, Andre

2014-10-01

This review is devoted to pharmacological applications of principles of release from capsules to overcome the membrane barrier. Many of these principles were developed in the context of polymeric multilayer capsule membrane modulation, but they are also pertinent to liposomes, polymersomes, capsosomes, particles, emulsion-based carriers and other carriers. We look at these methods from the physical, chemical or biological driving mechanisms point of view. In addition to applicability for carriers in drug delivery, these release methods are significant for another area directly related to pharmacology - modulation of the permeability of the membranes and thus promoting the action of drugs. Emerging technologies, including ionic current monitoring through a lipid membrane on a nanopore, are also highlighted. Copyright © 2014 Elsevier Ltd. All rights reserved.

Concerted regulation of retinal pigment epithelium basement membrane and barrier function by angiocrine factors.

Science.gov (United States)

Benedicto, Ignacio; Lehmann, Guillermo L; Ginsberg, Michael; Nolan, Daniel J; Bareja, Rohan; Elemento, Olivier; Salfati, Zelda; Alam, Nazia M; Prusky, Glen T; Llanos, Pierre; Rabbany, Sina Y; Maminishkis, Arvydas; Miller, Sheldon S; Rafii, Shahin; Rodriguez-Boulan, Enrique

2017-05-19

The outer blood-retina barrier is established through the coordinated terminal maturation of the retinal pigment epithelium (RPE), fenestrated choroid endothelial cells (ECs) and Bruch's membrane, a highly organized basement membrane that lies between both cell types. Here we study the contribution of choroid ECs to this process by comparing their gene expression profile before (P5) and after (P30) the critical postnatal period when mice acquire mature visual function. Transcriptome analyses show that expression of extracellular matrix-related genes changes dramatically over this period. Co-culture experiments support the existence of a novel regulatory pathway: ECs secrete factors that remodel RPE basement membrane, and integrin receptors sense these changes triggering Rho GTPase signals that modulate RPE tight junctions and enhance RPE barrier function. We anticipate our results will spawn a search for additional roles of choroid ECs in RPE physiology and disease.

Response of exfoliated human buccal epithelium cells to combined gamma radiation, microwaves, and magnetic field exposure estimated by changes in chromatin condensation and cell membrane permeability

Directory of Open Access Journals (Sweden)

K. А. Kuznetsov

2016-11-01

Full Text Available Modulation of the biological effects produced by ionizing radiation (IR using microwave and magnetic fields has important theoretical and practical applications. Response of human buccal epithelium cells to different physical agents (single and combined exposure to 0.5–5 Gy γ-radiation (60Co; microwaves with the frequency of 36.64 GHz and power densities of 0.1 and 1 W/m2, and static magnetic field with the intensity of 25 mT has been investigated. The stress response of the cells was evaluated by counting heterochromatin granules quantity (HGQ in the cell nuclei stained with orcein. Membrane permeability was assessed by the percentage of cells stained with indigocarmine (cells with damaged membrane. The increase of heterochromatin granules quantity (HGQ, i.e. chromatin condensation was detected at the doses of 2 Gy and higher. Changes in the cell membrane permeability to indigocarmine expressed the threshold effect. Membrane permeability reached the threshold at the doses of 2–3 Gy for the cells of different donors and did not change with the increase of the dose of γ-radiation. Cells obtained from different donors revealed some individual peculiarities in their reaction to γ-radiation. The static magnetic field and microwaves applied before or after γ-radiation decreased its impact, as revealed by means of HGQ assessment.

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

Adsorption of amylase enzyme on ultrafiltration membranes

DEFF Research Database (Denmark)

Beier, Søren; Enevoldsen, Ann Dorrit; Kontogeorgis, Georgios

2007-01-01

A method to measure the static adsorption on membrane surfaces has been developed and described. The static adsorption of an amylase-F has been measured on two different ultrafiltration membranes, both with a cut-off value of 10 kDa (a PES membrane and the ETNA10PP membrane, which is a surface......-modified PVDF membrane). The adsorption follows the Langmuir adsorption theory. Thus, the static adsorption consists of monolayer coverage. The static adsorption is expressed both as a permeability drop and an adsorption resistance. From the adsorption isotherms the maximum static permeability drops...... and the maximum static adsorption resistances are determined. The maximum static permeability drop for the hydrophobic PES membrane is 75 % and the maximum static adsorption resistance is 0.014 m2hbar/L. The maximum static permeability drop for the hydrophilic surface-modified PVDF membrane (ETNA10PP) is 23...

Enhancing hydrophilicity and water permeability of PET track-etched membranes by advanced oxidation process

International Nuclear Information System (INIS)

Korolkov, Ilya V.; Mashentseva, Anastassiya A.; Güven, Olgun; Zdorovets, Maxim V.; Taltenov, Abzal A.

2015-01-01

In this study we present results on the application of advanced oxidation systems for effective and non-toxic oxidation of poly(ethylene terephthalate) track-etched membranes (PET TeMs) to improve their wettability and water transport properties. Two oxidizing systems: H 2 O 2 under UV irradiation (H 2 O 2 /UV) and Fenton system under visible light (Fenton/H 2 O 2 /Vis) were compared. The surface of functionalized PET TeMs was characterized by using colorimetric assay, contact angle measurements and X-ray photoelectron spectroscopy (XPS). Results clearly showed that water permeability of PET TeMs treated with H 2 O 2 /UV was improved by 28 ± 5% compared with etched-only membrane, the same parameter was found to increase by 13 ± 4% in the case of Fenton/H 2 O 2 /Vis treatment. The proposed oxidation technique is very simple, environment friendly and not requiring special equipment or expensive chemicals. The surface hydrophilicity of the membranes stored for 360 days in air between paper sheets was analyzed by contact angle test, colorimetric assay to measure concentration of carboxylic groups on the surface with toluidine blue and XPS analysis. The hydrophilic properties of oxidized PET TeMs were found to be stable for a long period of time.

Enhancing hydrophilicity and water permeability of PET track-etched membranes by advanced oxidation process

Science.gov (United States)

Korolkov, Ilya V.; Mashentseva, Anastassiya A.; Güven, Olgun; Zdorovets, Maxim V.; Taltenov, Abzal A.

2015-12-01

In this study we present results on the application of advanced oxidation systems for effective and non-toxic oxidation of poly(ethylene terephthalate) track-etched membranes (PET TeMs) to improve their wettability and water transport properties. Two oxidizing systems: H2O2 under UV irradiation (H2O2/UV) and Fenton system under visible light (Fenton/H2O2/Vis) were compared. The surface of functionalized PET TeMs was characterized by using colorimetric assay, contact angle measurements and X-ray photoelectron spectroscopy (XPS). Results clearly showed that water permeability of PET TeMs treated with H2O2/UV was improved by 28 ± 5% compared with etched-only membrane, the same parameter was found to increase by 13 ± 4% in the case of Fenton/H2O2/Vis treatment. The proposed oxidation technique is very simple, environment friendly and not requiring special equipment or expensive chemicals. The surface hydrophilicity of the membranes stored for 360 days in air between paper sheets was analyzed by contact angle test, colorimetric assay to measure concentration of carboxylic groups on the surface with toluidine blue and XPS analysis. The hydrophilic properties of oxidized PET TeMs were found to be stable for a long period of time.

Integrated evaluation of the performance of a more than seven year old permeable reactive barrier at a site contaminated with chlorinated aliphatic hydrocarbons (CAHs)

DEFF Research Database (Denmark)

Muchitsch, Nanna; Nooten, Thomas Van; Bastiaens, Leen

2011-01-01

An important issue of concern for permeable reactive iron barriers is the long-term efficiency of the barriers due to the long operational periods required. Mineral precipitation resulting from the anaerobic corrosion of the iron filings and bacteria present in the barrier may play an important...... performed equally well as virgin granular iron of the same type based on determined degradation rates despite that parts of the cored iron material were covered by mineral precipitates (especially iron sulfides, carbonate green rust and aragonite). The PCR analysis performed on the iron core samples...

The exhibition to ozone diminishes the adherence and increases the membrane permeability of macrophages alveolar of rate

International Nuclear Information System (INIS)

Garcia, J.

2000-01-01

Ozone gas is generated photochemically in areas with high levels of automotive or industrial emissions, and causes irritation and inflammation of the airways if inhaled. Rat alveolar macrophages were obtained by lung lavage from male Sprague Dawley rats and used as a model to assess ozone induced cell damage (0,594 ppm for up to 60 minutes). Ozone exposure caused loss of cell adherence to a polystyrene substrate and increased membrane permeability, as noted by increases in specific 51 Cr release and citoplasmic calcium levels. The results indicate that the cell membrane is a target for ozone damage. Elevations of cytoplasmic calcium could mediate other macrophage responses to ozone , including eicosanoid and nitric oxide production, with concomitant decreases in phagocytic ability and superoxide production. (Author) [es

Remediation of groundwater contaminated with the lead-phenol binary system by granular dead anaerobic sludge-permeable reactive barrier.

Science.gov (United States)

Faisal, Ayad A H; Abd Ali, Ziad T

2017-10-01

Computer solutions (COMSOL) Multiphysics 3.5a software was used for simulating the one-dimensional equilibrium transport of the lead-phenol binary system including the sorption process through saturated sandy soil as the aquifer and granular dead anaerobic sludge (GDAS) as the permeable reactive barrier. Fourier-transform infrared spectroscopy analysis proved that the carboxylic and alcohol groups are responsible for the bio-sorption of lead onto GDAS, while phosphines, aromatic and alkane are the functional groups responsible for the bio-sorption of phenol. Batch tests have been performed to characterize the equilibrium sorption properties of the GDAS and sandy soil in lead and/or phenol containing aqueous solutions. Numerical and experimental results proved that the barrier plays a potential role in the restriction of the contaminant plume migration and there is a linear relationship between longevity and thickness of the barrier. A good agreement between these results was recognized with root mean squared error not exceeding 0.04.

Membrane dynamics

DEFF Research Database (Denmark)

Bendix, Pól Martin

2015-01-01

Current topics include membrane-protein interactions with regard to membrane deformation or curvature sensing by BAR domains. Also, we study the dynamics of membrane tubes of both cells and simple model membrane tubes. Finally, we study membrane phase behavior which has important implications...... for the lateral organization of membranes as wells as for physical properties like bending, permeability and elasticity...

Membrane fouling mechanism of biofilm-membrane bioreactor (BF-MBR): Pore blocking model and membrane cleaning.

Science.gov (United States)

Zheng, Yi; Zhang, Wenxiang; Tang, Bing; Ding, Jie; Zheng, Yi; Zhang, Zhien

2018-02-01

Biofilm membrane bioreactor (BF-MBR) is considered as an important wastewater treatment technology that incorporates advantages of both biofilm and MBR process, as well as can alleviate membrane fouling, with respect to the conventional activated sludge MBR. But, to be efficient, it necessitates the establishment of proper methods for the assessment of membrane fouling. Four Hermia membrane blocking models were adopted to quantify and evaluate the membrane fouling of BF-MBR. The experiments were conducted with various operational conditions, including membrane types, agitation speeds and transmembrane pressure (TMP). Good agreement between cake formation model and experimental data was found, confirming the validity of the Hermia models for assessing the membrane fouling of BF-MBR and that cake layer deposits on membrane. Moreover, the influences of membrane types, agitation speeds and transmembrane pressure on the Hermia pore blocking coefficient of cake layer were investigated. In addition, the permeability recovery after membrane cleaning at various operational conditions was studied. This work confirms that, unlike conventional activated sludge MBR, BF-MBR possesses a low degree of membrane fouling and a higher membrane permeability recovery after cleaning. Copyright © 2017 Elsevier Ltd. All rights reserved.

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.)

Research in Water Permeability of Poly(ethylene) Terephthalate Track Membranes Modified by Polymerization of Dimethylaniline under the Action of Direct Current Discharge

CERN Document Server

Kravets, L I; Drachev, A I

2004-01-01

The properties of poly(ethylene) terephthalate track membranes modified by polymerization of dimethylaniline in a discharge of direct current are investigated. The influence of conditions of plasma treatment on the basic characteristics of the membranes (pore size, wettability, surface charge, water permeability) is studied. It is shown that under the action of discharge, a polymeric layer is formed on the membrane surface that can swell in solutions with low pH values. It has been found that the degree of the swelling stipulated by the conformation transfer of macromolecules of the deposited polymeric layer depends upon the size of relative magnification of the mass of the membrane during its plasma treatment. It is also shown that the obtained membranes can reversibly react to changing the pH of solution and applied pressure.

Characteristics of membranes which are suitable for isotopic separation by gaseous diffusion; Caracteristiques des barrieres utilisables pour la separation isotopique par diffusion gazeuse

Energy Technology Data Exchange (ETDEWEB)

Massignon, D [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

1958-07-01

In this article we shall briefly describe how results obtained from the experimental analysis of the structure of membranes can be used on the one hand for determining this structure and on the other hand as a result for example of the detection of too many large pores or micro fissures and the existence of leaks at the joints, for eliminating membranes which can not be used industrially. Here we shall only consider the utilisation of information given by measurement of the specific permeability G{sub 0}, the pore radius for the molecular (diffusion) regime r{sub mol.}, the pore radius for the viscous diffusion regime the pore radius for the intermediate stage of diffusion, r{sub wicke}, the pore radius r{sub sep.} which is used for determining the actual separation, the distribution of the pore radius defined by mercury symmetry, the B.E.T. and central X ray diffusion. First of all we shall give the definition which is adopted in practice for these empirical values, which can be adapted for a rapid analysis of the quality of membranes by comparing them with the same measurements carried out on standard porous samples. In a second section we show in a few cases which have occurred in routine measurement how by comparison it is possible to eliminate membranes which do not have a suitable structure. (author) [French] Dans cet expose, nous allons montrer sommairement comment les resultats donnes par les methodes experimentales de controle de la structure des barrieres peuvent, d'une part, conduire a une certaine representation de cette structure et, d'autre part, permettre d'eliminer les barrieres non utilisables industriellement en detectant par exemple les trop nombreux gros pores ou microfissures et l'existence de fuites aux joints. Nous nous limiterons ici a l'exploitation des renseignements donnes par la permeabilite specifique G{sub 0}, le rayon de pore r{sub mol.} effectif en regime moleculaire, le rayon de pore r{sub visq.} effectif en regime visqueux, le

Acoustic cavitation-based monitoring of the reversibility and permeability of ultrasound-induced blood-brain barrier opening.

Science.gov (United States)

Sun, Tao; Samiotaki, Gesthimani; Wang, Shutao; Acosta, Camilo; Chen, Cherry C; Konofagou, Elisa E

2015-12-07

Cavitation events seeded by microbubbles have been previously reported to be associated with MR- or fluorescent-contrast enhancement after focused ultrasound (FUS)-induced blood-brain barrier (BBB) opening. However, it is still unknown whether bubble activity can be correlated with the reversibility (the duration of opening and the likelihood of safe reinstatement) and the permeability of opened BBB, which is critical for the clinical translation of using passive cavitation detection to monitor, predict and control the opening. In this study, the dependence of acoustic cavitation on the BBB opening duration, permeability coefficient and histological damage occurrence were thus investigated. Transcranial pulsed FUS at 1.5 MHz in the presence of systemically circulating microbubbles was applied in the mouse hippocampi (n  =  60). The stable and inertial cavitation activities were monitored during sonication. Contrast-enhanced MRI was performed immediately after sonication and every 24 h up to 6 d thereafter, to assess BBB opening, brain tissue permeability and potential edema. Histological evaluations were used to assess the occurrence of neurovascular damages. It was found that stable cavitation was well correlated with: (1) the duration of the BBB opening (r(2)  =  0.77); (2) the permeability of the opened BBB (r(2)  =  0.82); (3) the likelihood of safe opening (P  cavitation dose was correlated with the resulting BBB permeability (r(2)  =  0.72). Stable cavitation was found to be more reliable than inertial cavitation at assessing the BBB opening within the pressure range used in this study. This study demonstrates that the stable cavitation response during BBB opening holds promise for predicting and controlling the restoration and pharmacokinetics of FUS-opened BBB. The stable cavitation response therefore showed great promise in predicting the BBB opening duration, enabling thus control of opening according to the drug

Biomimetic membranes and methods of making biomimetic membranes

Science.gov (United States)

Rempe, Susan; Brinker, Jeffrey C.; Rogers, David Michael; Jiang, Ying-Bing; Yang, Shaorong

2016-11-08

The present disclosure is directed to biomimetic membranes and methods of manufacturing such membranes that include structural features that mimic the structures of cellular membrane channels and produce membrane designs capable of high selectivity and high permeability or adsorptivity. The membrane structure, material and chemistry can be selected to perform liquid separations, gas separation and capture, ion transport and adsorption for a variety of applications.

Dietary Virgin Olive Oil Reduces Blood Brain Barrier Permeability, Brain Edema, and Brain Injury in Rats Subjected to Ischemia-Reperfusion

Directory of Open Access Journals (Sweden)

Fatemeh Mohagheghi

2010-01-01

Full Text Available Recent studies suggest that dietary virgin olive oil (VOO reduces hypoxia-reoxygenation injury in rat brain slices. We sought to extend these observations in an in vivo study of rat cerebral ischemia-reperfusion injury. Four groups, each consisting of 18 Wistar rats, were studied. One group (control received saline, while three treatment groups received oral VOO (0.25, 0.5, and 0.75 mL/kg/day, respectively. After 30 days, blood lipid profiles were determined, before a 60-min period of middle cerebral artery occlusion (MCAO. After 24-h reperfusion, neurological deficit scores, infarct volume, brain edema, and blood brain barrier permeability were each assessed in subgroups of six animals drawn from each main group. VOO reduced the LDL/HDL ratio in doses of 0.25, 0.5, and 0.75 mL/kg/day in comparison to the control group (p < 0.05, and offered cerebroprotection from ischemia-reperfusion. For controls vs. doses of 0.25 vs. 0.5 vs. 0.75 mL/kg/day, attenuated corrected infarct volumes were 207.82 ± 34.29 vs. 206.41 ± 26.23 vs. 124.21 ± 14.73 vs. 108.46 ± 31.63 mm3; brain water content of the infarcted hemisphere was 82 ±± 0.25 vs. 81.5 ± 0.56 vs. 80.5 ± 0.22 vs. 80.5 ± 0.34%; and blood brain barrier permeability of the infarcted hemisphere was 11.31 ± 2.67 vs. 9.21 ± 2.28 vs. 5.83 ± 1.6 vs. 4.43 ± 0.93 µg/g tissue (p < 0.05 for measures in doses 0.5 and 0.75 mL/kg/day vs. controls. Oral administration of VOO reduces infarct volume, brain edema, blood brain barrier permeability, and improves neurologic deficit scores after transient MCAO in rats.

Permeability recovery of fouled forward osmosis membranes by chemical cleaning during a long-term operation of anaerobic osmotic membrane bioreactors treating low-strength wastewater.

Science.gov (United States)

Wang, Xinhua; Hu, Taozhan; Wang, Zhiwei; Li, Xiufen; Ren, Yueping

2017-10-15

Anaerobic osmotic membrane bioreactor (AnOMBR) has gained increasing interests in wastewater treatment owing to its simultaneous recovery of biogas and water. However, the forward osmosis (FO) membrane fouling was severe during a long-term operation of AnOMBRs. Here, we aim to recover the permeability of fouled FO membranes by chemical cleaning. Specifically speaking, an optimal chemical cleaning procedure was searched for fouled thin film composite polyamide FO (TFC-FO) membranes in a novel microfiltration (MF) assisted AnOMBR (AnMF-OMBR). The results indicated that citric acid, disodium ethylenediaminetetraacetate (EDTA-2Na), hydrochloric acid (HCl), sodium dodecyl sulfate (SDS) and sodium hydroxide (NaOH) had a low cleaning efficiency of less than 15%, while hydrogen peroxide (H 2 O 2 ) could effectively remove foulants from the TFC-FO membrane surface (almost 100%) through oxidizing the functional group of the organic foulants and disintegrating the colloids and microbe flocs into fine particles. Nevertheless, the damage of H 2 O 2 to the TFC-FO membrane was observed when a high cleaning concentration and a long duration were applied. In this case, the optimal cleaning conditions including cleaning concentration and time for fouled TFC-FO membranes were selected through confocal laser scanning microscope (CLSM) and scanning electron microscopy (SEM) images and the flux recovery rate. The results suggested that the optimal cleaning procedure for fouled TFC-FO membranes was use of 0.5% H 2 O 2 at 25 °C for 6 h, and after that, the cleaned TFC-FO membrane had the same performance as a virgin one including water flux and rejection for organic matters and phosphorus during the operation of AnMF-OMBR. Copyright © 2017 Elsevier Ltd. All rights reserved.

Dissociation of changes in the permeability of the blood-brain barrier from catecholamine-induced changes in blood pressure of normotensive and spontaneously hypertensive rats

International Nuclear Information System (INIS)

Sankar, R.; Domer, F.R.; Taylor, B.

1982-01-01

Researchers have studied the effects of the pressor catecholamine, dopamine, and the depressor catecholamine, isoproterenol, on the systemic blood pressure and the permeability of the blood-brain barrier (BBB) to albumin in normotensive (WKY) and spontaneously hypertensive (SHR) rats. The rats were anesthetized with pentobarbital. The permeability of the BBB to protein was measured by the extravasation of radioiodinated serum albumin (RISA). The permeability was decreased by both catecholamines despite the dose-dependent, yet opposite, changes in blood pressure in the WKY rats. The blood pressure response to both of the catecholamines was enhanced in the SHR rats. Isoproterenol caused a decrease in the permeability of the BBB in the SHR but dopamine did not. Results with both WKY and SHR rats are suggestive of an adrenergically-mediated decrease in movement across the BBB of compounds of large molecular weight, regardless of changes in blood pressure

The Effect of Micro-Channels in the MPL on the Predicted Membrane Water Content in a PEMFC – A Modeling Study

DEFF Research Database (Denmark)

Berning, Torsten

2014-01-01

The micro-porous layer (MPL) in a proton exchange membrane fuel cell is frequently believed to constitute a barrier for the liquid water owing to its low hydraulic permeability compared to the porous substrate. When micro-channels are carved into the MPL on the side facing the catalyst layer, liq...

Role of different biodegradable polymers on the permeability of ciprofloxacin

OpenAIRE

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

2014-01-01

Since permeability across biological membranes is a key factor in the absorption and distribution of drugs, drug permeation characteristics of three oral suspensions of ciprofloxacin were designed and compared. The three suspensions of ciprofloxacin were prepared by taking biodegradable polymers such as carbopol 934, carbopol 940, and hydroxypropyl methylcellulose (HPMC). The permeability study was performed by using a Franz diffusion cell through both synthetic cellulose acetate membrane and...

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.

Enhancing hydrophilicity and water permeability of PET track-etched membranes by advanced oxidation process

Energy Technology Data Exchange (ETDEWEB)

Korolkov, Ilya V.; Mashentseva, Anastassiya A. [Institute of Nuclear Physics, Ibrahimov Str., 1, 050032 Almaty (Kazakhstan); The L.N. Gumilyov Eurasian National University, Satpaev Str., 5, 010008 Astana (Kazakhstan); Güven, Olgun [Department of Chemistry, Hacettepe University, 06800 Beytepe, Ankara (Turkey); Zdorovets, Maxim V. [Institute of Nuclear Physics, Ibrahimov Str., 1, 050032 Almaty (Kazakhstan); The L.N. Gumilyov Eurasian National University, Satpaev Str., 5, 010008 Astana (Kazakhstan); Taltenov, Abzal A. [The L.N. Gumilyov Eurasian National University, Satpaev Str., 5, 010008 Astana (Kazakhstan)

2015-12-15

In this study we present results on the application of advanced oxidation systems for effective and non-toxic oxidation of poly(ethylene terephthalate) track-etched membranes (PET TeMs) to improve their wettability and water transport properties. Two oxidizing systems: H{sub 2}O{sub 2} under UV irradiation (H{sub 2}O{sub 2}/UV) and Fenton system under visible light (Fenton/H{sub 2}O{sub 2}/Vis) were compared. The surface of functionalized PET TeMs was characterized by using colorimetric assay, contact angle measurements and X-ray photoelectron spectroscopy (XPS). Results clearly showed that water permeability of PET TeMs treated with H{sub 2}O{sub 2}/UV was improved by 28 ± 5% compared with etched-only membrane, the same parameter was found to increase by 13 ± 4% in the case of Fenton/H{sub 2}O{sub 2}/Vis treatment. The proposed oxidation technique is very simple, environment friendly and not requiring special equipment or expensive chemicals. The surface hydrophilicity of the membranes stored for 360 days in air between paper sheets was analyzed by contact angle test, colorimetric assay to measure concentration of carboxylic groups on the surface with toluidine blue and XPS analysis. The hydrophilic properties of oxidized PET TeMs were found to be stable for a long period of time.

[Chromogranin A derived peptide CGA47-66 inhibits hyper-permeability of blood brain barrier in mice with sepsis].

Science.gov (United States)

Zeng, Yan; Zhang, Dan; Jiang, Liping; Wei, Fu; Xu, Shan

2016-02-01

To explore the effect of chromofungin (CHR), a chromogranin A (CGA) derived peptide CGA47-66, on hyper-permeability of blood brain barrier in septic mice. 120 healthy male C57BL/6 mice were randomly divided into groups, with 12 mice in each group. Seventy-two mice were used for dynamic observation of the contents of water and Evan blue (EB) in brain tissue after being treated with lipopolysaccharide (LPS). Another 48 mice were divided into normal saline control group (NS group), LPS induced sepsis model group (LPS group), low-dose CHR pretreatment group (CL+LPS group), and high-dose CHR pretreatment group (CH+LPS group). The septic model was reproduced by intraperitoneal injection of 10 mg/kg LPS 0.1 mL, and the mice in NS group was given equal volume of normal saline. The mice in CL+LPS group and CH+LPS group were intraperitoneally injected with 15.5 μg/kg and 77.5 μg/kg CHR 10 minutes before LPS injection. Six hours after LPS injection, 4 mL/kg of 2% EB was injected via caudal vein, the contents of water and EB in brain tissue were determined, and EB immune fluorescence in brain tissue was determined to assess the changes in permeability of blood brain barrier. Brain pathology was observed with hematoxylin and eosin (HE) staining. With the extension of time after LPS injection, the contents of water and EB in brain tissue were gradually increased, and the time of difference with statistical significance appeared earlier when compared with that of control group in the contents of water than that in EB contents (3 hours and 6 hours, respectively). The contents of water and EB in brain tissue in LPS group were significantly increased as compared with NS group [water content: (79.77±0.62)% vs. (78.28±0.44)%, P water and EB contents in brain tissue induced by LPS, and the effect was more significant in CH+LPS group [water content: (78.15±0.73)% vs. (79.77±0.62)%, EB (μg/g): 7.09±2.59 vs. 13.87±4.50, both P leakage in LPS group was more marked than that of NS

GOHAL!: sustainable membranes for alcohol dehydration

DEFF Research Database (Denmark)

Boffa, Vittorio

2017-01-01

the pristine graphene oxide membrane. The enhanced water permeability along with the good water/ethanol selectivity makes the GO-HAL membranes promising devices for alcohol dehydration technologies. This study provides a new basis for the rational design of the future generation of GO-based membranes......Treat, H2020-MSCA-RISE-2014 (n. 64555). [1] V. Boffa et. al., Carbon-based building blocks for alcohol dehydration membranes with disorder-enhanced water permeability, Carbon, under review....

Analytical model for the design of in situ horizontal permeable reactive barriers (HPRBs) for the mitigation of chlorinated solvent vapors in the unsaturated zone

NARCIS (Netherlands)

Verginelli, Iason; Capobianco, Oriana; Hartog, Niels; Baciocchi, Renato

In this work we introduce a 1-D analytical solution that can be used for the design of horizontal permeable reactive barriers (HPRBs) as a vapor mitigation system at sites contaminated by chlorinated solvents. The developed model incorporates a transient diffusion-dominated transport with a

Calcium permeability of the T lymphocyte plasma membrane: counteraction of phorbol ester and A23187

Energy Technology Data Exchange (ETDEWEB)

Csermely, P.; Szamel, M.; Somogyi, J.

1986-01-01

The intracellular calcium concentration (Ca/sub i/) of T lymphocytes was measured using the fluorescent indicator quin2. Different ionophores effectively enhanced the Ca permeability of the plasma membrane. The effective concentration of the ionophores required for permeabilization increased in the order of ionomycin, A23187 and X537-A (lasalocid-A). 12-0-tetradecanoyl-phorbol-13-acetate (TPA) in submicromolar concentrations did not change Ca/sub i/. The addition of TPA immediately before the A23187-permeabilization did not alter the Ca ionophoretic effect of A23187. However, prolonged incubation with TPA decreased the efficiency of A23187 permeabilizing the plasma membrane for calcium ions. This effect was concentration and time dependent, being maximal at TPA concentrations higher than 10 nM with a preincubation time of 1.5 hours. TPA induced relative A23187 insensitivity is most probably not due to a direct effect of TPA on the ionophore as it is concentration and time dependent. Moreover the fluorescence and fluorescence polarization of A23187 as well as the energy transfer between the tryptophan groups of the membrane proteins and A23187 showed no significant change during incubation with TPA. These results indicate that membrane fluidity changes or A23187 immobilization also do not play a prominent role in the explanation of the phenomenon. However the supposed intracellular heavy metal content of T lymphocyte might be a possible source of the TPA induced relative insensitization towards A23187.

Zero-Valent Iron Permeable Reactive Barriers: A Review of Performance

International Nuclear Information System (INIS)

Korte, NE

2001-01-01

This report briefly reviews issues regarding the implementation of the zero-valent iron permeable reactive barrier (PRB) technology at sites managed by the U.S. Department of Energy (DOE). Initially, the PRB technology, using zero-valent iron for the reactive media, was received with great enthusiasm, and DOE invested millions of dollars testing and implementing PRBs. Recently, a negative perception of the technology has been building. This perception is based on the failure of some deployments to satisfy goals for treatment and operating expenses. The purpose of this report, therefore, is to suggest reasons for the problems that have been encountered and to recommend whether DOE should invest in additional research and deployments. The principal conclusion of this review is that the most significant problems have been the result of insufficient characterization, which resulted in poor engineering implementation. Although there are legitimate concerns regarding the longevity of the reactive media, the ability of zero-valent iron to reduce certain chlorinated hydrocarbons and to immobilize certain metals and radionuclides is well documented. The primary problem encountered at some DOE full-scale deployments has been an inadequate assessment of site hydrology, which resulted in misapplication of the technology. The result is PRBs with higher than expected flow velocities and/or incomplete plume capture

Acute Acrolein Exposure Induces Impairment of Vocal Fold Epithelial Barrier Function.

Directory of Open Access Journals (Sweden)

Xinxin Liu

Full Text Available Acrolein is a ubiquitous pollutant abundant in cigarette smoke, mobile exhaust, and industrial waste. There is limited literature on the effects of acrolein on vocal fold tissue, although there are clinical reports of voice changes after pollutant exposures. Vocal folds are responsible for voice production. The overall objective of this study was to investigate the effects of acrolein exposure on viable, excised vocal fold epithelial tissue and to characterize the mechanism underlying acrolein toxicity. Vocal fold epithelia were studied because they form the outermost layer of the vocal folds and are a primary recipient of inhaled pollutants. Porcine vocal fold epithelia were exposed to 0, 50, 100, 500, 900 or 1300 μM of acrolein for 3 hours; the metabolic activity, epithelial resistance, epithelial permeability, tight junction protein (occludin and claudin 3 expression, cell membrane integrity and lipid peroxidation were investigated. The data demonstrated that acrolein exposure at 500 μM significantly reduced vocal fold epithelial metabolic activity by 27.2% (p≤0.001. Incubation with 100 μM acrolein caused a marked increase in epithelial permeability by 130.5% (p<0.05 and a reduction in transepithelial electrical resistance (TEER by 180.0% (p<0.001. While the expression of tight junctional protein did not change in acrolein-treated samples, the cell membrane integrity was significantly damaged with a 45.6% increase of lipid peroxidation as compared to controls (p<0.05. Taken together, these data provide evidence that acute acrolein exposure impairs vocal fold epithelial barrier integrity. Lipid peroxidation-induced cell membrane damage may play an important role in reducing the barrier function of the epithelium.

Facile fabrication of aloe vera containing PCL nanofibers for barrier membrane application.

Science.gov (United States)

Carter, Princeton; Rahman, Shekh M; Bhattarai, Narayan

2016-01-01

Guided tissue regeneration (GTR) is a widely used method in dental surgical procedures that utilizes a barrier membrane to exclude migration of epithelium and ensure repopulation of periodontal ligament cells at the sites having insufficient gingiva. Commercial GTR membranes are typically composed of synthetic polymers that have had mild clinical success mostly because of their lack of proper bioactivity and appropriate degradation profile. In this study, a natural polymer, aloe vera was blended with polycaprolactone (PCL) to create nanofibrous GTR membranes by electrospinning. Aloe vera has proven anti-inflammatory properties and enhances the regeneration of periodontium tissues. PCL, a synthetic polymer, is well known to produce miscible polyblends nanofibers with natural polymers. Nanofibrous membranes with varying composition of PCL to aloe vera were fabricated, and several physicochemical and biological properties, such as fiber morphology, wettability, chemical structure, mechanical strength, and cellular compatibility of the membranes were analyzed. PCL/aloe vera membranes with ratios from 100/00 to 70/30 showed good uniformity in fiber morphology and suitable mechanical properties, and retained the integrity of their fibrous structure in aqueous solutions. Experimental results, using cell viability assay and cell attachment observation, showed that the nanofibrous membranes support 3T3 cell viability and could be a potential candidate for GTR therapy.

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...

Syntheses of prodrug-type phosphotriester oligonucleotides responsive to intracellular reducing environment for improvement of cell membrane permeability and nuclease resistance.

Science.gov (United States)

Hayashi, Junsuke; Samezawa, Yusuke; Ochi, Yosuke; Wada, Shun-Ichi; Urata, Hidehito

2017-07-15

We synthesized prodrug-type phosphotriester (PTE) oligonucleotides containing the six-membered cyclic disulfide moiety by using phosphoramidite chemistry. Prodrug-type oligonucleotides named "Reducing-Environment-Dependent Uncatalyzed Chemical Transforming (REDUCT) PTE oligonucleotides" were converted into natural oligonucleotides under cytosol-mimetic reductive condition. Furthermore, the REDUCT PTE oligonucleotides were robust to nuclease digestion and exhibited good cell membrane permeability. Copyright © 2017 Elsevier Ltd. All rights reserved.

[Removal of nitrate from groundwater using permeable reactive barrier].

Science.gov (United States)

Li, Xiu-Li; Yang, Jun-Jun; Lu, Xiao-Xia; Zhang, Shu; Hou, Zhen

2013-03-01

To provide a cost-effective method for the remediation of nitrate-polluted groundwater, column experiments were performed to study the removal of nitrate by permeable reactive barrier filled with fermented mulch and sand (biowall), and the mechanisms and influence factors were explored. The experimental results showed that the environmental condition in the simulated biowall became highly reduced after three days of operation (oxidation-reduction potential was below - 100 mV), which was favorable for the reduction of nitrate. During the 15 days of operation, the removal rate of nitrate nitrogen (NO3(-) -N) by the simulated biowall was 80%-90% (NO3(-)-N was reduced from 20 mg x L(-1) in the inlet water to 1.6 mg x L(-1) in the outlet water); the concentration of nitrite nitrogen (NO2(-) -N) in the outlet water was below 2.5 mg x L(-1); the concentration of ammonium nitrogen (NH4(+) -N) was low in the first two days but increased to about 12 mg x L(-1) since day three. The major mechanisms involved in the removal of nitrate nitrogen were adsorption and biodegradation. When increasing the water flow velocity in the simulated biowall, the removal rate of NO3(-) -N was reduced and the concentration of NH4(+) -N in the outlet water was significantly reduced. A simulated zeolite wall was set up following the simulated biowall and 98% of the NH4(+) -N could be removed from the water.

Isoproterenol attenuates high vascular pressure-induced permeability increases in isolated rat lungs.

Science.gov (United States)

Parker, J C; Ivey, C L

1997-12-01

To separate the contributions of cellular and basement membrane components of the alveolar capillary barrier to the increased microvascular permeability induced by high pulmonary venous pressures (Ppv), we subjected isolated rat lungs to increases in Ppv, which increased capillary filtration coefficient (Kfc) without significant hemorrhage (31 cmH2O) and with obvious extravasation of red blood cells (43 cmH2O). Isoproterenol (20 microM) was infused in one group (Iso) to identify a reversible cellular component of injury, and residual blood volumes were measured to assess extravasation of red blood cells through ruptured basement membranes. In untreated lungs (High Ppv group), Kfc increased 6.2 +/- 1.3 and 38.3 +/- 15.2 times baseline during the 31 and 43 cmH2O Ppv states. In Iso lungs, Kfc was 36.2% (P Kfc increases at moderate Ppv, possibly because of an endothelial effect, but it did not affect red cell extravasation at higher vascular pressures.

Current progress in the permeability and its enhancement approches for TCM active ingredients across blood-eye barrier

Directory of Open Access Journals (Sweden)

Yu-Yang Bai

2014-10-01

Full Text Available Blood-eye barrier(BEBis one of the most important structures of organism to maintain homeostasis of the eye. However, it is the major constraint for the medication of intraocular diseases. Traditional Chinese medicines have distinctive advantages for the treatment of intraocular diseases, which can be used to regulate the physiological function of human body with low toxicity. In this article, we have briefly summarized the feature of BEB, with the domestic and foreign literatures combined, and mainly reviewed current progress in the field of study on the permeability of traditional Chinese medicines and effective components in BEB and promoting methods.

The solubility-permeability interplay and its implications in formulation design and development for poorly soluble drugs.

Science.gov (United States)

Dahan, Arik; Miller, Jonathan M

2012-06-01

While each of the two key parameters of oral drug absorption, the solubility and the permeability, has been comprehensively studied separately, the relationship and interplay between the two have been largely ignored. For instance, when formulating a low-solubility drug using various solubilization techniques: what are we doing to the apparent permeability when we increase the solubility? Permeability is equal to the drug's diffusion coefficient through the membrane times the membrane/aqueous partition coefficient divided by the membrane thickness. The direct correlation between the intestinal permeability and the membrane/aqueous partitioning, which in turn is dependent on the drug's apparent solubility in the GI milieu, suggests that the solubility and the permeability are closely associated, exhibiting a certain interplay between them, and the current view of treating the one irrespectively of the other may not be sufficient. In this paper, we describe the research that has been done thus far, and present new data, to shed light on this solubility-permeability interplay. It has been shown that decreased apparent permeability accompanies the solubility increase when using different solubilization methods. Overall, the weight of the evidence indicates that the solubility-permeability interplay cannot be ignored when using solubility-enabling formulations; looking solely at the solubility enhancement that the formulation enables may be misleading with regards to predicting the resulting absorption, and hence, the solubility-permeability interplay must be taken into account to strike the optimal solubility-permeability balance, in order to maximize the overall absorption.

Acoustic cavitation-based monitoring of the reversibility and permeability of ultrasound-induced blood-brain barrier opening

International Nuclear Information System (INIS)

Sun, Tao; Samiotaki, Gesthimani; Wang, Shutao; Acosta, Camilo; Chen, Cherry C; Konofagou, Elisa E

2015-01-01

Cavitation events seeded by microbubbles have been previously reported to be associated with MR- or fluorescent-contrast enhancement after focused ultrasound (FUS)-induced blood-brain barrier (BBB) opening. However, it is still unknown whether bubble activity can be correlated with the reversibility (the duration of opening and the likelihood of safe reinstatement) and the permeability of opened BBB, which is critical for the clinical translation of using passive cavitation detection to monitor, predict and control the opening. In this study, the dependence of acoustic cavitation on the BBB opening duration, permeability coefficient and histological damage occurrence were thus investigated. Transcranial pulsed FUS at 1.5 MHz in the presence of systemically circulating microbubbles was applied in the mouse hippocampi (n  =  60). The stable and inertial cavitation activities were monitored during sonication. Contrast-enhanced MRI was performed immediately after sonication and every 24 h up to 6 d thereafter, to assess BBB opening, brain tissue permeability and potential edema. Histological evaluations were used to assess the occurrence of neurovascular damages. It was found that stable cavitation was well correlated with: (1) the duration of the BBB opening (r 2   =  0.77); (2) the permeability of the opened BBB (r 2   =  0.82); (3) the likelihood of safe opening (P  <  0.05, safe opening compared to cases of damage; P  <  0.0001, no opening compared to safe opening). The inertial cavitation dose was correlated with the resulting BBB permeability (r 2   =  0.72). Stable cavitation was found to be more reliable than inertial cavitation at assessing the BBB opening within the pressure range used in this study. This study demonstrates that the stable cavitation response during BBB opening holds promise for predicting and controlling the restoration and pharmacokinetics of FUS-opened BBB. The stable cavitation response

Acoustic cavitation-based monitoring of the reversibility and permeability of ultrasound-induced blood-brain barrier opening

Science.gov (United States)

Sun, Tao; Samiotaki, Gesthimani; Wang, Shutao; Acosta, Camilo; Chen, Cherry C.; Konofagou, Elisa E.

2015-12-01

Cavitation events seeded by microbubbles have been previously reported to be associated with MR- or fluorescent-contrast enhancement after focused ultrasound (FUS)-induced blood-brain barrier (BBB) opening. However, it is still unknown whether bubble activity can be correlated with the reversibility (the duration of opening and the likelihood of safe reinstatement) and the permeability of opened BBB, which is critical for the clinical translation of using passive cavitation detection to monitor, predict and control the opening. In this study, the dependence of acoustic cavitation on the BBB opening duration, permeability coefficient and histological damage occurrence were thus investigated. Transcranial pulsed FUS at 1.5 MHz in the presence of systemically circulating microbubbles was applied in the mouse hippocampi (n  =  60). The stable and inertial cavitation activities were monitored during sonication. Contrast-enhanced MRI was performed immediately after sonication and every 24 h up to 6 d thereafter, to assess BBB opening, brain tissue permeability and potential edema. Histological evaluations were used to assess the occurrence of neurovascular damages. It was found that stable cavitation was well correlated with: (1) the duration of the BBB opening (r2  =  0.77) (2) the permeability of the opened BBB (r2  =  0.82) (3) the likelihood of safe opening (P  cases of damage; P  <  0.0001, no opening compared to safe opening). The inertial cavitation dose was correlated with the resulting BBB permeability (r2  =  0.72). Stable cavitation was found to be more reliable than inertial cavitation at assessing the BBB opening within the pressure range used in this study. This study demonstrates that the stable cavitation response during BBB opening holds promise for predicting and controlling the restoration and pharmacokinetics of FUS-opened BBB. The stable cavitation response therefore showed great promise in predicting the

Polyethersulfone/clay membranes and its water permeability; Membranas de polietersulfona/argila e sua permeabilidade a agua

Energy Technology Data Exchange (ETDEWEB)

Cavalho, Thamyres Cardoso de; Medeiros, Vanessa da Nobrega; Araujo, Edcleide Maria de; Lira, Helio Lucena, E-mail: thamyrescc@gmail.com, E-mail: vanismedeiros@gmail.com, E-mail: edcleide.araujo@ufcg.edu.br, E-mail: helio.lira@ufcg.edu.br [Universidade Federal de Campina Grande (UAEMa/CCT/UFCG), PB (Brazil). Unidade Academica de Engenharia de Materiais; Leite, Amanda Melissa Damiao, E-mail: amanda.leite@ect.ufrn.br [Universidade Federal do Rio Grande do Norte (ECT/UFRN), Natal, RN (Brazil). Escola de Ciencia e Tecnologia

2017-04-15

Membranes can be considered polymeric or inorganic films that function as a semipermeable barrier to filtration on a molecular scale, separating two phases and restricting, totally or partially, the transportation of one or more chemical species (solute) present in the solution. Therefore, the aim of this work is to produce polyethersulfone membranes (PES) and polyethersulfone/clay by phase inversion technique and evaluate the presence of clay in obtaining membranes for wastewater treatment. The used solvent was dimethylformamide (DMF) and clays were Brasgel PA (MMT) and Cloisite Na (CL Na) in the proportion of 3 to 5% (wt.). By Xray diffraction (XRD), the membranes with 3% of MMT and CL Na clays apparently had partially exfoliated structures. For the composition with 5% of CL Na a small peak was observed, which indicates that this is possibly an intercalated structure or microcomposite. By scanning electron microscopy (SEM), visualizes that the pure surface of the pure PES membrane a structure apparently without pores was observed in the used magnification and without roughness surface when compared to membranes with clay. The measurements of contact angle indicated that the inclusion of clay altered the wetting ability of the membranes. The flow with distilled water for all membranes started high and over time reached a stabilization level. Thus, it can be concluded that the presence and the content of clay altered the morphology of the membrane, contributing to an increase in water flow. (author)

Enhancing recovery of ammonia from swine manure anaerobic digester effluent using gas-permeable membrane technology.

Science.gov (United States)

Dube, P J; Vanotti, M B; Szogi, A A; García-González, M C

2016-03-01

Gas-permeable membrane technology is useful to recover ammonia from manure. In this study, the technology was enhanced using aeration instead of alkali chemicals to increase pH and the ammonium (NH4(+)) recovery rate. Digested effluents from covered anaerobic swine lagoons containing 1465-2097 mg NH4(+)-N L(-1) were treated using submerged membranes (0.13 cm(2) cm(-3)), low-rate aeration (120 mL air L-manure(-1) min(-1)) and nitrification inhibitor (22 mg L(-1)) to prevent nitrification. The experiment included a control without aeration. The pH of the manure with aeration rose from 8.6 to 9.2 while the manure without aeration decreased from 8.6 to 8.1. With aeration, 97-99% of the NH4(+) was removed in about 5 days of operation with 96-98% recovery efficiency. In contrast, without aeration it took 25 days to treat the NH4(+). Therefore, the recovery of NH4(+) was five times faster with the low-rate aeration treatment. This enhancement could reduce costs by 70%. Published by Elsevier Ltd.

Measurement of brain perfusion, blood volume, and blood-brain barrier permeability, using dynamic contrast-enhanced T(1)-weighted MRI at 3 tesla

DEFF Research Database (Denmark)

Larsson, Henrik B W; Courivaud, Frédéric; Rostrup, Egill

2009-01-01

Assessment of vascular properties is essential to diagnosis and follow-up and basic understanding of pathogenesis in brain tumors. In this study, a procedure is presented that allows concurrent estimation of cerebral perfusion, blood volume, and blood-brain permeability from dynamic T(1)-weighted...... on a pixel-by-pixel basis of cerebral perfusion, cerebral blood volume, and blood-brain barrier permeability.......Assessment of vascular properties is essential to diagnosis and follow-up and basic understanding of pathogenesis in brain tumors. In this study, a procedure is presented that allows concurrent estimation of cerebral perfusion, blood volume, and blood-brain permeability from dynamic T(1)-weighted...... imaging of a bolus of a paramagnetic contrast agent passing through the brain. The methods are applied in patients with brain tumors and in healthy subjects. Perfusion was estimated by model-free deconvolution using Tikhonov's method (gray matter/white matter/tumor: 72 +/- 16/30 +/- 8/56 +/- 45 mL/100 g...

Polyurethane Membranes Modified with Isopropyl Myristate as a Potential Candidate for Encapsulating Electronic Implants: A Study of Biocompatibility and Water Permeability

Directory of Open Access Journals (Sweden)

Deepen Paul

2010-07-01

Full Text Available Medical polyurethanes have shown good bio-stability and mechanical properties and have been used as coating for implantable medical devices. However, despite their excellent properties, they are relatively permeable to liquid water and water vapour which is a drawback for electronic implant encapsulation. In this study polyether polyurethanes with different soft segment molecular weights were modified by incorporating isopropyl myristate (IPM, as a hydrophobic modifying agent, and the effect of IPM on water resistant and biocompatibility of membranes were investigated. IPM changed the surface properties of the polyurethane film and reduced its surface energy. Polyurethane films were found to be stable with IPM concentrations of 1–5 wt% based upon their chemistry; however it leached out in BSA at higher concentrations. Though, low concentrations of IPM reduced both liquid water and water vapour permeability; at higher IPM content liquid permeability did not improved significantly. In general, the polyurethane materials showed much lower water permeability compared with currently used silicone packaging material for electronic implants. In addition, cytotoxicity assessment of IPM containing polyurethanes showed no evidence of cytotoxcity up to 5 wt% IPM.

Fabrication of Novel Hydrogel with Berberine-Enriched Carboxymethylcellulose and Hyaluronic Acid as an Anti-Inflammatory Barrier Membrane

Directory of Open Access Journals (Sweden)

Yu-Chih Huang

2016-01-01

Full Text Available An antiadhesion barrier membrane is an important biomaterial for protecting tissue from postsurgical complications. However, there is room to improve these membranes. Recently, carboxymethylcellulose (CMC incorporated with hyaluronic acid (HA as an antiadhesion barrier membrane and drug delivery system has been reported to provide excellent tissue regeneration and biocompatibility. The aim of this study was to fabricate a novel hydrogel membrane composed of berberine-enriched CMC prepared from bark of the P. amurense tree and HA (PE-CMC/HA. In vitro anti-inflammatory properties were evaluated to determine possible clinical applications. The PE-CMC/HA membranes were fabricated by mixing PE-CMC and HA as a base with the addition of polyvinyl alcohol to form a film. Tensile strength and ultramorphology of the membrane were evaluated using a universal testing machine and scanning electron microscope, respectively. Berberine content of the membrane was confirmed using a UV-Vis spectrophotometer at a wavelength of 260 nm. Anti-inflammatory property of the membrane was measured using a Griess reaction assay. Our results showed that fabricated PE-CMC/HA releases berberine at a concentration of 660 μg/ml while optimal plasticity was obtained at a 30 : 70 PE-CMC/HA ratio. The berberine-enriched PE-CMC/HA had an inhibited 60% of inflammation stimulated by LPS. These results suggest that the PE-CMC/HA membrane fabricated in this study is a useful anti-inflammatory berberine release system.

Robust High Performance Aquaporin based Biomimetic Membranes

DEFF Research Database (Denmark)

Helix Nielsen, Claus; Zhao, Yichun; Qiu, C.

2013-01-01

on top of a support membrane. Control membranes, either without aquaporins or with the inactive AqpZ R189A mutant aquaporin served as controls. The separation performance of the membranes was evaluated by cross-flow forward osmosis (FO) and reverse osmosis (RO) tests. In RO the ABM achieved a water......Aquaporins are water channel proteins with high water permeability and solute rejection, which makes them promising for preparing high-performance biomimetic membranes. Despite the growing interest in aquaporin-based biomimetic membranes (ABMs), it is challenging to produce robust and defect...... permeability of ~ 4 L/(m2 h bar) with a NaCl rejection > 97% at an applied hydraulic pressure of 5 bar. The water permeability was ~40% higher compared to a commercial brackish water RO membrane (BW30) and an order of magnitude higher compared to a seawater RO membrane (SW30HR). In FO, the ABMs had > 90...

Lipopolysaccharide precipitates hepatic encephalopathy and increases blood-brain barrier permeability in mice with acute liver failure.

Science.gov (United States)

Chastre, Anne; Bélanger, Mireille; Nguyen, Bich N; Butterworth, Roger F

2014-03-01

Acute liver failure (ALF) is frequently complicated by infection leading to precipitation of central nervous system complications such as hepatic encephalopathy (HE) and increased mortality. There is evidence to suggest that when infection occurs in ALF patients, the resulting pro-inflammatory mechanisms may be amplified that could, in turn, have a major impact on blood-brain barrier (BBB) function. The aim of this study was to investigate the role of endotoxemia on the progression of encephalopathy in relation to BBB permeability during ALF. Adult male C57-BL6 mice with ALF resulting from azoxymethane-induced toxic liver injury were administered trace amounts of the endotoxin component lipopolysaccharide (LPS). Effects on the magnitude of the systemic inflammatory response, liver pathology and BBB integrity were measured as a function of progression of HE, defined as time to loss of corneal reflex (coma). Lipopolysaccharide caused additional two- to seven-fold (P liver pathology and associated increases of circulating transaminases as well as increased hyperammonaemia consistent with a further loss of viable hepatocytes. LPS treatment of ALF mice led to a rapid precipitation of hepatic coma and the BBB became permeable to the 25-kDa protein immunoglobulin G (IgG). This extravasation of IgG was accompanied by ignificant up-regulation of matrix metalloproteinase-9 (MMP-9), an endopeptidase known to modulate opening of the BBB in a wide range of neurological disorders. These findings represent the first direct evidence of inflammation-related BBB permeability changes in ALF. © 2013 John Wiley & Sons A/S. Publishing by John Wiley & Sons Ltd.

Oxcarbazepine-loaded polymeric nanoparticles: development and permeability studies across in vitro models of the blood-brain barrier and human placental trophoblast.

Science.gov (United States)

Lopalco, Antonio; Ali, Hazem; Denora, Nunzio; Rytting, Erik

2015-01-01

Encapsulation of antiepileptic drugs (AEDs) into nanoparticles may offer promise for treating pregnant women with epilepsy by improving brain delivery and limiting the transplacental permeability of AEDs to avoid fetal exposure and its consequent undesirable adverse effects. Oxcarbazepine-loaded nanoparticles were prepared by a modified solvent displacement method from biocompatible polymers (poly(lactic-co-glycolic acid) [PLGA] with or without surfactant and PEGylated PLGA [Resomer(®) RGPd5055]). The physical properties of the developed nanoparticles were determined with subsequent evaluation of their permeability across in vitro models of the blood-brain barrier (hCMEC/D3 cells) and human placental trophoblast cells (BeWo b30 cells). Oxcarbazepine-loaded nanoparticles with encapsulation efficiency above 69% were prepared with sizes ranging from 140-170 nm, polydispersity indices below 0.3, and zeta potential values below -34 mV. Differential scanning calorimetry and X-ray diffraction studies confirmed the amorphous state of the nanoencapsulated drug. The apparent permeability (Pe ) values of the free and nanoencapsulated oxcarbazepine were comparable across both cell types, likely due to rapid drug release kinetics. Transport studies using fluorescently-labeled nanoparticles (loaded with coumarin-6) demonstrated increased permeability of surfactant-coated nanoparticles. Future developments in enzyme-prodrug therapy and targeted delivery are expected to provide improved options for pregnant patients with epilepsy.

Effects of casein glycomacropeptide supplementation on growth performance, intestinal morphology, intestinal barrier permeability and inflammatory responses in Escherichia coli K88 challenged piglets

Directory of Open Access Journals (Sweden)

Yili Rong

2015-06-01

Full Text Available Casein glycomacropeptide (CGMP is a bioactive peptide derived from milk with multiple functions. This study was aimed at evaluating the effects of CGMP as a potential feed additive on growth performance, intestinal morphology, intestinal barrier permeability and inflammatory responses of Escherichia coli K88 (E. coli K88 challenged piglets. Eighteen weaning piglets were randomly assigned to three groups. Control group and K88 challenged group received a basal diet, and CGMP treated group received the basal diet supplemented with 1% of CGMP powder. The trail lasted for 12 days, K88 was orally administered to the piglets of K88 challenged group and CGMP treated group on days 8–10. The results showed that the diet containing 1% CGMP significantly alleviated the decrease in average daily gain (P  0.05 and barrier permeability damage (P < 0.05, and acute inflammatory response (P < 0.05 induced by E. coli K88 infection. In conclusion, CGMP supplementation in the diet protected the weaning piglets against E. coli K88 infection.

Endothelial glycocalyx dysfunction in disease: albuminuria and increased microvascular permeability.

Science.gov (United States)

Salmon, Andrew H J; Satchell, Simon C

2012-03-01

Appreciation of the glomerular microcirculation as a specialized microcirculatory bed, rather than as an entirely separate entity, affords important insights into both glomerular and systemic microvascular pathophysiology. In this review we compare regulation of permeability in systemic and glomerular microcirculations, focusing particularly on the role of the endothelial glycocalyx, and consider the implications for disease processes. The luminal surface of vascular endothelium throughout the body is covered with endothelial glycocalyx, comprising surface-anchored proteoglycans, supplemented with adsorbed soluble proteoglycans, glycosaminoglycans and plasma constituents. In both continuous and fenestrated microvessels, this endothelial glycocalyx provides resistance to the transcapillary escape of water and macromolecules, acting as an integral component of the multilayered barrier provided by the walls of these microvessels (ie acting in concert with clefts or fenestrae across endothelial cell layers, basement membranes and pericytes). Dysfunction of any of these capillary wall components, including the endothelial glycocalyx, can disrupt normal microvascular permeability. Because of its ubiquitous nature, damage to the endothelial glycocalyx alters the permeability of multiple capillary beds: in the glomerulus this is clinically apparent as albuminuria. Generalized damage to the endothelial glycocalyx can therefore manifest as both albuminuria and increased systemic microvascular permeability. This triad of altered endothelial glycocalyx, albuminuria and increased systemic microvascular permeability occurs in a number of important diseases, such as diabetes, with accumulating evidence for a similar phenomenon in ischaemia-reperfusion injury and infectious disease. The detection of albuminuria therefore has implications for the function of the microcirculation as a whole. The importance of the endothelial glycocalyx for other aspects of vascular function

Kinetics of the flash-induced P515 response in relation to the H+-permeability of the membrane bound ATPase in spinach chloroplasts

Energy Technology Data Exchange (ETDEWEB)

Peters, R.L.; van Kooten, O.; Vredenberg, W.J.

1985-08-01

The effect of dicyclohexylcarbodiimide (DCCD) on the kinetics of the flash-induced P515 response and on the activity of the ATPase was investigated in isolated spinach chloroplasts. It was found that after the addition of 5 X 10(-8)mol DCCD the rate of ATP hydrolysis induced by a period of 60 sec illumination was decreased to less than 5% of its original value. At this concentration, hardly any effect, if at all, could be detected on the kinetics of the flash-induced P515 response, neither in dark-adapted nor in light-activated chloroplasts. It was concluded that the presence of concentrations of DCCD, sufficiently high to affect the ATPase activity, does not affect the kinetics of the flash-induced P515 response. Since DCCD decreases the H+ permeability of the membrane-bound ATPase, it was concluded that this permeability coefficient for protons is not an important factor in the regulation of the flash-induced membrane potential and, therefore, does not affect the kinetics of the flash-induced P515 response.

Polymer Inclusion Membranes with Strip Dispersion

Directory of Open Access Journals (Sweden)

Yueh-Hsien Li

2017-06-01

Full Text Available The present work investigated the permeation of indium ions through a polymer inclusion membrane (PIM, prepared with cellulose triacetate (CTA as the base polymer, tris(2-butoxyethyl phosphate (TBEP as the plasticizer and di-(2-ethylhexylphosphoric acid (D2EHPA as the extractant. With 5 M HCl aqueous solution as the strip solution, we observed an initial indium permeability of 2.4 × 10−4 m/min. However, the permeability decreases with time, dropping to about 3.4 × 10−5 m/min after 200 min of operation. Evidence was obtained showing that hydrolysis of CTA occurred, causing a dramatic decrease in the feed pH (protons transported from strip to feed solutions and a loss of extractant and plasticizer from the membrane, and then leading to the loss of indium permeability. To alleviate the problem of hydrolysis, we proposed an operation scheme called polymer inclusion membranes with strip dispersion: dispersing the strip solution in extractant-containing oil and then bringing the dispersion to contact with the polymer membrane. Since the strong acid was dispersed in oil, the membrane did not directly contact the strong acid at all times, and membrane hydrolysis was thus alleviated and the loss of indium permeability was effectively prevented. With the proposed scheme, a stable indium permeability of 2.5 × 10−4 m/min was obtained during the whole time period of the permeation experiment.

Rationalization of reduced penetration of drugs through ceramide gel phase membrane.

Science.gov (United States)

Paloncýová, Markéta; DeVane, Russell H; Murch, Bruce P; Berka, Karel; Otyepka, Michal

2014-11-25

Since computing resources have advanced enough to allow routine molecular simulation studies of drug molecules interacting with biologically relevant membranes, a considerable amount of work has been carried out with fluid phospholipid systems. However, there is very little work in the literature on drug interactions with gel phase lipids. This poses a significant limitation for understanding permeation through the stratum corneum where the primary pathway is expected to be through a highly ordered lipid matrix. To address this point, we analyzed the interactions of p-aminobenzoic acid (PABA) and its ethyl (benzocaine) and butyl (butamben) esters with two membrane bilayers, which differ in their fluidity at ambient conditions. We considered a dioleoylphosphatidylcholine (DOPC) bilayer in a fluid state and a ceramide 2 (CER2, ceramide NS) bilayer in a gel phase. We carried out unbiased (100 ns long) and biased z-constraint molecular dynamics simulations and calculated the free energy profiles of all molecules along the bilayer normal. The free energy profiles converged significantly slower for the gel phase. While the compounds have comparable affinities for both membranes, they exhibit penetration barriers almost 3 times higher in the gel phase CER2 bilayer. This elevated barrier and slower diffusion in the CER2 bilayer, which are caused by the high ordering of CER2 lipid chains, explain the low permeability of the gel phase membranes. We also compared the free energy profiles from MD simulations with those obtained from COSMOmic. This method provided the same trends in behavior for the guest molecules in both bilayers; however, the penetration barriers calculated by COSMOmic did not differ between membranes. In conclusion, we show how membrane fluid properties affect the interaction of drug-like molecules with membranes.

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

Science.gov (United States)

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

2018-05-01

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

Membranes, methods of making membranes, and methods of separating gases using membranes

Science.gov (United States)

Ho, W. S. Winston

2012-10-02

Membranes, methods of making membranes, and methods of separating gases using membranes are provided. The membranes can include at least one hydrophilic polymer, at least one cross-linking agent, at least one base, and at least one amino compound. The methods of separating gases using membranes can include contacting a gas stream containing at least one of CO.sub.2, H.sub.2S, and HCl with one side of a nonporous and at least one of CO.sub.2, H.sub.2S, and HCl selectively permeable membrane such that at least one of CO.sub.2, H.sub.2S, and HCl is selectively transported through the membrane.

Interaction of abscisic acid with phospholipid membranes

International Nuclear Information System (INIS)

Stillwell, W.; Brengle, B.; Hester, P.; Wassall, S.T.

1989-01-01

The plant hormone abscisic acid (ABA) is shown, under certain conditions, to greatly enhance the permeability of phospholipid bilayer membranes to the nonelectrolyte erythritol (followed spectrophotometrically by osmotic swelling) and the anion carboxyfluorescein (followed by fluorescence). The hormone is ineffective with single- and mixed-component phosphatidylcholine membranes in the liquid-crystalline or gel states. In contrast, substantial ABA-induced permeability is measured for two-component membranes containing lipids with different polar head groups or containing phosphatidylcholines with different acyl chains at temperatures where gel and liquid-crystalline phases coexist. Despite the large ABA-induced enhancement in bilayer permeability, no evidence for a substantial change at the molecular level was seen in the membranes by magnetic resonance techniques. 13 C NMR spin-lattice relaxation times, T 1 , in sonicated unilamellar vesicles and ESR of spin-labeled fatty acids intercalated into membranes showed negligible effect on acyl chain order and dynamics within the bilayer, while 31 P NMR of sonicated unilamellar vesicles indicated negligible effect on molecular motion and conformation in the head-group region. The authors propose that, instead of causing a general nonspecific perturbation to the membrane, the hormone acts at membrane defects formed due to mismatch in molecular packing where two different head groups or acyl chain states interface. Increased membrane disruption by ABA at these points of membrane instability could then produce an enhancement in permeability

On the Mechanism(s of Membrane Permeability Transition in Liver Mitochondria of Lamprey, Lampetra fluviatilis L.: Insights from Cadmium

Directory of Open Access Journals (Sweden)

Elena A. Belyaeva

2014-01-01

Full Text Available Previously we have shown that opening of the mitochondrial permeability transition pore in its low conductance state is the case in hepatocytes of the Baltic lamprey (Lampetra fluviatilis L. during reversible metabolic depression taking place in the period of its prespawning migration when the exogenous feeding is switched off. The depression is observed in the last year of the lamprey life cycle and is conditioned by reversible mitochondrial dysfunction (mitochondrial uncoupling in winter and coupling in spring. To further elucidate the mechanism(s of induction of the mitochondrial permeability transition pore in the lamprey liver, we used Cd2+ and Ca2+ plus Pi as the pore inducers. We found that Ca2+ plus Pi induced the high-amplitude swelling of the isolated “winter” mitochondria both in isotonic sucrose and ammonium nitrate medium while both low and high Cd2+ did not produce the mitochondrial swelling in these media. Low Cd2+ enhanced the inhibition of basal respiration rate of the “winter” mitochondria energized by NAD-dependent substrates whereas the same concentrations of the heavy metal evoked its partial stimulation on FAD-dependent substrates. The above changes produced by Cd2+ or Ca2+ plus Pi in the “winter” mitochondria were only weakly (if so sensitive to cyclosporine A (a potent pharmacological desensitizer of the nonselective pore added alone and they were not sensitive to dithiothreitol (a dithiol reducing agent. Under monitoring of the transmembrane potential of the “spring” lamprey liver mitochondria, we revealed that Cd2+ produced its decrease on both types of the respiratory substrates used that was strongly hampered by cyclosporine A, and the membrane potential was partially restored by dithiothreitol. The effects of different membrane permeability modulators on the lamprey liver mitochondria function and the seasonal changes in their action are discussed.

Laminar oxy-fuel diffusion flame supported by an oxygen-permeable-ion-transport membrane

KAUST Repository

Hong, Jongsup

2013-03-01

A numerical model with detailed gas-phase chemistry and transport was used to predict homogeneous fuel conversion processes and to capture the important features (e.g., the location, temperature, thickness and structure of a flame) of laminar oxy-fuel diffusion flames stabilized on the sweep side of an oxygen permeable ion transport membrane (ITM). We assume that the membrane surface is not catalytic to hydrocarbon or syngas oxidation. It has been demonstrated that an ITM can be used for hydrocarbon conversion with enhanced reaction selectivity such as oxy-fuel combustion for carbon capture technologies and syngas production. Within an ITM unit, the oxidizer flow rate, i.e., the oxygen permeation flux, is not a pre-determined quantity, since it depends on the oxygen partial pressures on the feed and sweep sides and the membrane temperature. Instead, it is influenced by the oxidation reactions that are also dependent on the oxygen permeation rate, the initial conditions of the sweep gas, i.e., the fuel concentration, flow rate and temperature, and the diluent. In oxy-fuel combustion applications, the sweep side is fuel-diluted with CO2, and the entire unit is preheated to achieve a high oxygen permeation flux. This study focuses on the flame structure under these conditions and specifically on the chemical effect of CO2 dilution. Results show that, when the fuel diluent is CO2, a diffusion flame with a lower temperature and a larger thickness is established in the vicinity of the membrane, in comparison with the case in which N2 is used as a diluent. Enhanced OH-driven reactions and suppressed H radical chemistry result in the formation of products with larger CO and H2O and smaller H2 concentrations. Moreover, radical concentrations are reduced due to the high CO2 fraction in the sweep gas. CO2 dilution reduces CH3 formation and slows down the formation of soot precursors, C2H2 and C2H4. The flame location impacts the species diffusion and heat transfer from the

Radioactive rare gas separation using a separation cell with two kinds of membrane differing in gas permeability tendency

International Nuclear Information System (INIS)

Ohno, Masayoshi; Ozaki, Osamu; Sato, Hajime; Kimura, Shoji; Miyauchi, Terukatsu.

1977-01-01

A separation cell embodying two kinds of membrane-porous and nonporous, i.e. differing in gas permeability - has a separation factor higher than possible with a conventional separation cell with a single kind of membrane. The performance of such separation cells and of cascades constituted thereof are analyzed theoretically and measured experimentally for different conditions of operation, to determine the applicability of the concept to the separation of rare gases from gaseous waste out of nuclear plants. Theoretical considerations indicate that, in a cascade composed of symmetric separation cells, the separation performance can be improved by recycling part of the effluent from a cell back through the same cell (recycling cascade). It is shown that its performance is better than with the arrangement of diverting another effluent several stages upstream. With the recycling cascade, the symmetric separation recycling rate is determined by the depletion separation and enrichment separation factors relevant to the respective membranes. The separation performance of a 9-stage recycling cascade composed of separation cells with silicone rubber tubular membranes and cellulose acetate tubular membranes is derived for a case of Kr separation from N 2 -Kr mixture. The experimental data coincide well with the analytical results. From both the experimental and the analytical results, it is found that the attainable separation coefficient per stage of the cascade comes to average approximately 0.97. (auth.)

Anti-fouling and high water permeable forward osmosis membrane fabricated via layer by layer assembly of chitosan/graphene oxide

Science.gov (United States)

Salehi, Hasan; Rastgar, Masoud; Shakeri, Alireza

2017-08-01

To date, forward osmosis (FO) has received considerable attention due to its potential application in seawater desalination. FO does not require external hydraulic pressure and consequently is believed to have a low fouling propensity. Despite the numerous privileges of FO process, a major challenge ahead for its development is the lack of high performance membranes. In this study, we fabricated a novel highly-efficient FO membrane using layer-by-layer (LbL) assembly of positive chitosan (CS) and negative graphene oxide (GO) nanosheets via electrostatic interaction on a porous support layer. The support layer was prepared by blending hydrophilic sulfonated polyethersulfone (SPES) into polyethersulfone (PES) matrix using wet phase inversion process. Various characterization techniques were used to confirm successful fabrication of LbL membrane. The number of layers formed on the SPES-PES support layer was easily adjusted by repeating the CS and GO deposition cycles. Thin film composite (TFC) membrane was also prepared by the same SPES-PES support layer and polyamide (PA) active layer to compare membranes performances. The water permeability and salt rejection of the fabricated membranes were obtained by two kinds of draw solutions (including Na2SO4 and sucrose) under two different membrane orientations. The results showed that membrane coated by a CS/GO bilayers had water flux of 2-4 orders of magnitude higher than the TFC one. By increasing the number of CS/GO bilayers, the selectivity of the LbL membrane was improved. The novel fabricated LbL membrane showed better fouling resistance than the TFC one in the feed solution containing 200 ppm of sodium alginate as a foulant model.

Contribution of liver mitochondrial membrane-bound glutathione transferase to mitochondrial permeability transition pores

International Nuclear Information System (INIS)

Hossain, Quazi Sohel; Ulziikhishig, Enkhbaatar; Lee, Kang Kwang; Yamamoto, Hideyuki; Aniya, Yoko

2009-01-01

We recently reported that the glutathione transferase in rat liver mitochondrial membranes (mtMGST1) is activated by S-glutathionylation and the activated mtMGST1 contributes to the mitochondrial permeability transition (MPT) pore and cytochrome c release from mitochondria [Lee, K.K., Shimoji, M., Quazi, S.H., Sunakawa, H., Aniya, Y., 2008. Novel function of glutathione transferase in rat liver mitochondrial membrane: role for cytochrome c release from mitochondria. Toxcol. Appl. Pharmacol. 232, 109-118]. In the present study we investigated the effect of reactive oxygen species (ROS), generator gallic acid (GA) and GST inhibitors on mtMGST1 and the MPT. When rat liver mitochondria were incubated with GA, mtMGST1 activity was increased to about 3 fold and the increase was inhibited with antioxidant enzymes and singlet oxygen quenchers including 1,4-diazabicyclo [2,2,2] octane (DABCO). GA-mediated mtMGST1 activation was prevented by GST inhibitors such as tannic acid, hematin, and cibacron blue and also by cyclosporin A (CsA). In addition, GA induced the mitochondrial swelling which was also inhibited by GST inhibitors, but not by MPT inhibitors CsA, ADP, and bongkrekic acid. GA also released cytochrome c from the mitochondria which was inhibited completely by DABCO, moderately by GST inhibitors, and somewhat by CsA. Ca 2+ -mediated mitochondrial swelling and cytochrome c release were inhibited by MPT inhibitors but not by GST inhibitors. When the outer mitochondrial membrane was isolated after treatment of mitochondria with GA, mtMGST1 activity was markedly increased and oligomer/aggregate of mtMGST1 was observed. These results indicate that mtMGST1 in the outer mitochondrial membrane is activated by GA through thiol oxidation leading to protein oligomerization/aggregation, which may contribute to the formation of ROS-mediated, CsA-insensitive MPT pore, suggesting a novel mechanism for regulation of the MPT by mtMGST1

Gas phase fractionation method using porous ceramic membrane

Science.gov (United States)

Peterson, Reid A.; Hill, Jr., Charles G.; Anderson, Marc A.

1996-01-01

Flaw-free porous ceramic membranes fabricated from metal sols and coated onto a porous support are advantageously used in gas phase fractionation methods. Mean pore diameters of less than 40 .ANG., preferably 5-20 .ANG. and most preferably about 15 .ANG., are permeable at lower pressures than existing membranes. Condensation of gases in small pores and non-Knudsen membrane transport mechanisms are employed to facilitate and increase membrane permeability and permselectivity.

In vitro evaluation of electrospun chitosan mats crosslinked with genipin as guided tissue regeneration barrier membranes

Science.gov (United States)

Norowski, Peter Andrew, Jr.

Guided tissue regeneration (GTR) is a surgical technique commonly used to exclude bacteria and soft tissues from bone graft sites in oral/maxillofacial bone graft sites by using a barrier membrane to maintain the graft contour and space. Current clinical barrier membrane materials based on expanded polytetrafluoroethylene (ePTFE) and bovine type 1 collagen are non-ideal and experience a number of disadvantages including membrane exposure, bacterial colonization/biofilm formation and premature degradation, all of which result in increased surgical intervention and poor bone regeneration. These materials do not actively participate in tissue regeneration, however bioactive materials, such as chitosan, may provide advantages such as the ability to stimulate wound healing and de novo bone formation. Our hypothesis is that electrospun chitosan GTR membranes will support cell attachment and growth but prevent cell infiltration/penetration of membrane, demonstrate in vitro degradation predictive of 4--6 month in vivo functionality, and will deliver antibiotics locally to prevent/inhibit periopathogenic complications. To test this hypothesis a series of chitosan membranes were electrospun, in the presence or absence of genipin, a natural crosslinking agent, at concentrations of 5 and 10 mM. These membranes were characterized by scanning electron microscopy, tensile testing, suture pullout testing, Fourier transform infrared spectroscopy, X-ray diffraction, and gel permeation chromatography, and in vitro biodegradation for diameter/morphology of fibers, membrane strengths, degree of crosslinking, crystallinity, molecular weight, and degradation kinetics, respectively. Cytocompability of membranes was evaluated in osteoblastic, fibroblastic and monocyte cultures. The activity of minocycline loaded and released from the membranes was determined in zone of inhibition tests using P. gingivalis microbe. The results demonstrated that genipin crosslinking extended the in vitro

Study on the application of permeable reactive barriers for remediation of uranium mine pit water

International Nuclear Information System (INIS)

Li Na'na; Zhu Yucheng

2012-01-01

Permeable reactive barrier (PRB) is economical and convenient on in suit remediation of polluted groundwater. In this paper, according to characteristics of uranium mine pit water, laboratory-scale PRB reactors were designed with the mixture of valent iron, active carbon, hydrated lime and quartz sands as reaction media. The feasibility and effectiveness of treating uranium mine pit water by PRB were tested under 3 different proportions of contaminants through dynamic simulation tests, which came out the optimal proportion of contaminants. The result indicated that the remediation effect of reactor B was the best, whose average removal rate to U was up to 99%. The quality of effluent attained the relevant standards, which indicated that the PRB technology is a feasible method for the treatment of uranium mine pit water. (authors)

Use of a permeable biological reaction barrier for groundwater remediation at a uranium mill tailings remedial action (UMTRA) site

International Nuclear Information System (INIS)

Thombre, M.S.; Thomson, B.M.; Barton, L.L.

1997-01-01

Previous work at the University of New Mexico and elsewhere has shown that sulfate reducing bacteria are capable of reducing uranium from the soluble +6 oxidation state to the insoluble +4 oxidation state. This chemistry forms the basis of a proposed groundwater remediation strategy in which microbial reduction would be used to immobilize soluble uranium. One such system would consist of a subsurface permeable barrier which would stimulate microbial growth resulting in the reduction of sulfate and nitrate and immobilization of metals while permitting the unhindered flow of ground water through it. This research investigated some of the engineering considerations associated with a microbial reducing barrier such as identifying an appropriate biological substrate, estimating the rate of substrate utilization, and identifying the final fate of the contaminants concentrated in the barrier matrix. The performance of batch reactors and column systems that treated simulated plume water was evaluated using cellulose, wheat straw, alfalfa hay, sawdust, and soluble starch as substrates. The concentrations of sulfate, nitrate, and U(VI) were monitored over time. Precipitates from each system were collected and the precipitated U(IV) was determined to be crystalline UO 2 (s) by X-ray Diffraction. The results of this study support the proposed use of cellulosic substrates as candidate barrier materials

Permeability of endothelial and astrocyte cocultures: in vitro blood-brain barrier models for drug delivery studies.

Science.gov (United States)

Li, Guanglei; Simon, Melissa J; Cancel, Limary M; Shi, Zhong-Dong; Ji, Xinying; Tarbell, John M; Morrison, Barclay; Fu, Bingmei M

2010-08-01

The blood-brain barrier (BBB) is a major obstacle for drug delivery to the brain. To seek for in vitro BBB models that are more accessible than animals for investigating drug transport across the BBB, we compared four in vitro cultured cell models: endothelial monoculture (bEnd3 cell line), coculture of bEnd3 and primary rat astrocytes (coculture), coculture with collagen type I and IV mixture, and coculture with Matrigel. The expression of the BBB tight junction proteins in these in vitro models was assessed using RT-PCR and immunofluorescence. We also quantified the hydraulic conductivity (L (p)), transendothelial electrical resistance (TER) and diffusive solute permeability (P) of these models to three solutes: TAMRA, Dextran 10K and Dextran 70K. Our results show that L (p) and P of the endothelial monoculture and coculture models are not different from each other. Compared with in vivo permeability data from rat pial microvessels, P of the endothelial monoculture and coculture models are not significantly different from in vivo data for Dextran 70K, but they are 2-4 times higher for TAMRA and Dextran 10K. This suggests that the endothelial monoculture and all of the coculture models are fairly good models for studying the transport of relatively large solutes across the BBB.

Proton conductive montmorillonite-Nafion composite membranes for direct ethanol fuel cells

Science.gov (United States)

Wu, Xiu-Wen; Wu, Nan; Shi, Chun-Qing; Zheng, Zhi-Yuan; Qi, Hong-Bin; Wang, Ya-Fang

2016-12-01

The preparation of Nafion membranes modified with montmorillonites is less studied, and most relative works mainly applied in direct methanol fuel cells, less in direct ethanol fuel cells. Organic/inorganic composite membranes are prepared with different montmorillonites (Ca-montmorillonite, Na-montmorillonite, K-montmorillonite, Mg-montmorillonite, and H-montmorillonite) and Nafion solution via casting method at 293 K in air, and with balance of their proton conductivity and ethanol permeability. The ethanol permeability and proton conductivity of the membranes are comparatively studied. The montmorillonites can well decrease the ethanol permeability of the membranes via inserted them in the membranes, while less decrease the proton conductivities of the membranes depending on the inserted amount and type of montmorillonites. The proton conductivities of the membranes are between 36.0 mS/cm and 38.5 mS/cm. The ethanol permeability of the membranes is between 0.69 × 10-6 cm2/s and 2.67 × 10-6 cm2/s.

Oxcarbazepine-loaded polymeric nanoparticles: development and permeability studies across in vitro models of the blood–brain barrier and human placental trophoblast

Science.gov (United States)

Lopalco, Antonio; Ali, Hazem; Denora, Nunzio; Rytting, Erik

2015-01-01

Encapsulation of antiepileptic drugs (AEDs) into nanoparticles may offer promise for treating pregnant women with epilepsy by improving brain delivery and limiting the transplacental permeability of AEDs to avoid fetal exposure and its consequent undesirable adverse effects. Oxcarbazepine-loaded nanoparticles were prepared by a modified solvent displacement method from biocompatible polymers (poly(lactic-co-glycolic acid) [PLGA] with or without surfactant and PEGylated PLGA [Resomer® RGPd5055]). The physical properties of the developed nanoparticles were determined with subsequent evaluation of their permeability across in vitro models of the blood–brain barrier (hCMEC/D3 cells) and human placental trophoblast cells (BeWo b30 cells). Oxcarbazepine-loaded nanoparticles with encapsulation efficiency above 69% were prepared with sizes ranging from 140–170 nm, polydispersity indices below 0.3, and zeta potential values below -34 mV. Differential scanning calorimetry and X-ray diffraction studies confirmed the amorphous state of the nanoencapsulated drug. The apparent permeability (Pe) values of the free and nanoencapsulated oxcarbazepine were comparable across both cell types, likely due to rapid drug release kinetics. Transport studies using fluorescently-labeled nanoparticles (loaded with coumarin-6) demonstrated increased permeability of surfactant-coated nanoparticles. Future developments in enzyme-prodrug therapy and targeted delivery are expected to provide improved options for pregnant patients with epilepsy. PMID:25792832

NOVEL CERAMIC MEMBRANE FOR HIGH TEMPERATURE CARBON DIOXIDE SEPARATION

International Nuclear Information System (INIS)

Ida, Jun-ichi; Yang, Zhaohui; Lin, Jerry Y.S.

2002-01-01

A new CO 2 semi-permeable dense inorganic membrane consisting of a porous metal phase and molten carbonate was proposed. A simple direct infiltration method was used to synthesize the metal-carbonate dual-phase membrane. Hermetic (gas-tight) dual phase membrane was successfully obtained. Permeation data showed that nitrogen or helium is not permeable through the membrane (only CO 2 , with O 2 can permeate through the membrane based on transport mechanism)

Evaluation of performance of barrier materials in geological disposal of radioactive waste

International Nuclear Information System (INIS)

Sasakura, Takeshi; Kobayashi, Ichizo

2004-01-01

It is important to evaluate the hydraulic and mechanical performance of barrier materials for geological disposal of radioactive waste. Many experiments on the hydraulic and mechanical performance of barrier materials have been implemented. However, both the ordinary water head-controlled permeability test for evaluating hydraulic performance and the oedometer test for obtaining the mechanical properties are usually needed. In this study, the flow pump permeability test was applied to various barrier materials with the purpose of quickly evaluating their hydraulic performance. The flow pump permeability test was shown to be applicable to every barrier material employed in this study, of which the coefficient of permeability ranged from 10-7 to 10-14 m/sec. The time needed to obtain the coefficient of permeability was about 1/8 that of ordinary head-controlled permeability tests. The resulting coefficient of permeability was more accurate than that from the standard water head-controlled permeability test. Moreover, the bentonite-engineered barrier materials were subjected to a constant strain rate consolidation test, which is a method to quickly evaluate the mechanical performance. The results of the consolidation tests were consistent with the results of the oedometer tests and the necessary time for the test was reduced to only four days even in case of Na-ben-tonite, for which a couple of months was necessary with the standard oedometer test. (author)

Barriers and post-closure monitoring (AL121125)

International Nuclear Information System (INIS)

Bostick, K.V.; Janecky, D.

1995-01-01

This project focuses on the rapid implementation of near-surface barriers, biotreatment, and post-closure monitoring technology. It uses water-permeable and biologic barriers that chemically capture and/or degrade contaminants without significantly altering the natural water flow regime. Barrier approaches are being tested for two different applications. The first is the use of barriers for confinement of chemical contaminants for in-trench treatments with leach systems or an in-place bioreactor. The second is an enhancement of the current practice of emplacing grout or clay slurry walls into direct horizontal surface and subsurface water flows around a contaminated area by integrating permeable reactive barriers and petroleum reservoir gel/foam/polymer technology

A simple, fast and accurate in-situ method to measure the rate of transport of redox species through membranes for lithium batteries

Science.gov (United States)

Meddings, Nina; Owen, John R.; Garcia-Araez, Nuria

2017-10-01

Lithium ion conducting membranes are important to protect the lithium metal electrode and act as a barrier to crossover species such as polysulphides in Li-S systems, redox mediators in Li-O2 cells or dissolved cathode species or electrolyte oxidation products in high voltage Li-ion batteries. We present an in-situ method for measuring permeability of membranes to crossover redox species. The method employs a 'Swagelok' cell design equipped with a glassy carbon working electrode, in which redox species are placed initially in the counter electrode compartment only. Permeability through the membrane, which separates working and counter electrodes, is determined using a square wave voltammetry technique that allows the concentration of crossover redox species to be evaluated over time with very high precision. We test the method using a model and well-behaved electrochemical system to demonstrate its sensitivity, reproducibility and reliability relative to alternative approaches. This new method offers advantages in terms of small electrolyte volume, and simple, fast, quantitative and in-situ measurement.

Thin-film Nanofibrous Composite Membranes Containing Cellulose or Chitin Barrier Layers Fabricated by Ionic Liquids

Energy Technology Data Exchange (ETDEWEB)

H Ma; B Hsiao; B Chu

2011-12-31

The barrier layer of high-flux ultrafiltration (UF) thin-film nanofibrous composite (TFNC) membranes for purification of wastewater (e.g., bilge water) have been prepared by using cellulose, chitin, and a cellulose-chitin blend, regenerated from an ionic liquid. The structures and properties of regenerated cellulose, chitin, and a cellulose-chitin blend were analyzed with thermogravimetric analysis (TGA) and wide-angle X-ray diffraction (WAXD). The surface morphology, pore size and pore size distribution of TFNC membranes were determined by SEM images and molecular weight cut-off (MWCO) methods. An oil/water emulsion, a model of bilge water, was used as the feed solution, and the permeation flux and rejection ratio of the membranes were investigated. TFNC membranes based on the cellulose-chitin blend exhibited 10 times higher permeation flux when compared with a commercial UF membrane (PAN10, Sepro) with a similar rejection ratio after filtration over a time period of up to 100 h, implying the practical feasibility of such membranes for UF applications.

A polygeneration from a dual-gas partial catalytic oxidation coupling with an oxygen-permeable membrane reactor

International Nuclear Information System (INIS)

Hao, Yanhong; Huang, Yi; Gong, Minhui; Li, Wenying; Feng, Jie; Yi, Qun

2015-01-01

Highlights: • A new polygeneration system (PL-PCO-OPMR) to DME/methanol/power is proposed. • Exergeo-economic analysis is adopted to disclose the performance of systems. • Key technological conditions and parameters for PL-PCO-OPMR are optimized. • PL-PCO-OPMR shows high energy efficiency and low CO_2 emission. • PL-PCO-OPMR is an attractive way for high efficient and clean use of COG and CGG. - Abstract: Polygeneration system, typically involving chemicals/fuels and electricity co-production, is a promising technology for the sustainable development of energy and environment. In this study, a new polygeneration system based on coal and coke oven gas (COG) inputs for co-production of dimethyl ether (DME)/methanol and electricity is proposed. In the new system, an appropriate syngas for the synthesis of DME is from coal gasified gas (CGG) reforming of COG coupled with an oxygen-permeable membrane reactor, in which both COG and CGG reforming process and fuel combustion process are incorporated, which reduces exergy destruction in the whole reforming process. In order to obtain the best performance of CO_2 reduction, energy saving and economic benefit, the key operation parameters of the proposed process are analyzed and optimized. The new system is compared with the process based on CH_4/CO_2 dry reforming, in terms of exergy efficiency, exergy cost and CO_2 emissions. Through the new system, the exergy efficiency can be increased by 7.8%, the exergy cost can be reduced by 0.88 USD/GJ and the CO_2 emission can be reduced by 0.023 kg/MJ. These results suggest that the polygeneration system from CGG and COG partial catalytic oxidation coupling with an oxygen-permeable membrane reactor (PL-PCO-OPMR) would be a more attractive way for highly efficient and clean use of CGG and COG.

Evaluation of flexible membrane liners as long-term barriers for uranium mill tailings

International Nuclear Information System (INIS)

1984-07-01

The National Uranium Tailings Program has commissioned a study to evaluate flexible membrane liners (geomembranes) as long-term barriers for Canadian uranium mill tailings. This study reviews the common liner type and addresses flexible liners (polymeric membranes and asphalt) in detail. Liner fabrication, design, installation, and performance are reviewed. Conceptual designs are presented for basins to accommodate 20 years accumulation of uranium tailings from mills in Elliot Lake and southeastern Athabasca. Nine polymeric and three asphalt liner types have been considered with respect to the physical and chemical environment in the uranium producing areas of Canada. All materials indicate good chemical resistance to uranium wastes but are subject to installation problems

Skin Membrane Electrical Impedance Properties under the Influence of a Varying Water Gradient

Science.gov (United States)

Björklund, Sebastian; Ruzgas, Tautgirdas; Nowacka, Agnieszka; Dahi, Ihab; Topgaard, Daniel; Sparr, Emma; Engblom, Johan

2013-01-01

The stratum corneum (SC) is an effective permeability barrier. One strategy to increase drug delivery across skin is to increase the hydration. A detailed description of how hydration affects skin permeability requires characterization of both macroscopic and molecular properties and how they respond to hydration. We explore this issue by performing impedance experiments on excised skin membranes in the frequency range 1 Hz to 0.2 MHz under the influence of a varying gradient in water activity (aw). Hydration/dehydration induces reversible changes of membrane resistance and effective capacitance. On average, the membrane resistance is 14 times lower and the effective capacitance is 1.5 times higher when the outermost SC membrane is exposed to hydrating conditions (aw = 0.992), as compared to the case of more dehydrating conditions (aw = 0.826). Molecular insight into the hydration effects on the SC components is provided by natural-abundance 13C polarization transfer solid-state NMR and x-ray diffraction under similar hydration conditions. Hydration has a significant effect on the dynamics of the keratin filament terminals and increases the interchain spacing of the filaments. The SC lipids are organized into lamellar structures with ∼ 12.6 nm spacing and hexagonal hydrocarbon chain packing with mainly all-trans configuration of the acyl chains, irrespective of hydration state. Subtle changes in the dynamics of the lipids due to mobilization and incorporation of cholesterol and long-chain lipid species into the fluid lipid fraction is suggested to occur upon hydration, which can explain the changes of the impedance response. The results presented here provide information that is useful in explaining the effect of hydration on skin permeability. PMID:23790372

Proton conductive montmorillonite-Nafion composite membranes for direct ethanol fuel cells

International Nuclear Information System (INIS)

Wu, Xiu-Wen; Wu, Nan; Shi, Chun-Qing; Zheng, Zhi-Yuan; Qi, Hong-Bin; Wang, Ya-Fang

2016-01-01

Highlights: • Composite membranes are prepared with different montmorillonites and nafion solution. • Proton conductivities of the composite membranes are between 36.0 mS/cm and 38.5 mS/cm. • Ethanol permeability is between 0.69 × 10"−"6 cm"2/s and 2.67 × 10"−"6 cm"2/s. • Water uptake is approximately 24.30 mass%. - Abstract: The preparation of Nafion membranes modified with montmorillonites is less studied, and most relative works mainly applied in direct methanol fuel cells, less in direct ethanol fuel cells. Organic/inorganic composite membranes are prepared with different montmorillonites (Ca-montmorillonite, Na-montmorillonite, K-montmorillonite, Mg-montmorillonite, and H-montmorillonite) and Nafion solution via casting method at 293 K in air, and with balance of their proton conductivity and ethanol permeability. The ethanol permeability and proton conductivity of the membranes are comparatively studied. The montmorillonites can well decrease the ethanol permeability of the membranes via inserted them in the membranes, while less decrease the proton conductivities of the membranes depending on the inserted amount and type of montmorillonites. The proton conductivities of the membranes are between 36.0 mS/cm and 38.5 mS/cm. The ethanol permeability of the membranes is between 0.69 × 10"−"6 cm"2/s and 2.67 × 10"−"6 cm"2/s.

Scintigraphic assessment of vascularity and blood-tissue barrier of human brain tumours

International Nuclear Information System (INIS)

Front, D.

1978-01-01

Assessment of vascularity and blood-tissue barrier was performed by sequential scintigraphy in 43 patients with brain tumours. The blood-tumour barrier was evaluated by use of sup(99m)Tc-pertechnetate, and vascularity using sup(99m)Tc-labelled red blood cells. Three groups of tumours were found: tumours with low vascularity and permeable barrier, tumours with high vascularity and permeable barrier, and tumours with low vascularity and relatively impermeable barrier. The first group indicates that when vessels are permeable, there may be a rapid penetration of large amounts of pertechnetate into the tumour even when vascularity is not increased. In the other two groups penetration of pertechnetate into the tumour is affected by vascularity, as it determines the total area where passage of the radiopharmaceutical takes place. It is suggested that the permeability of the blood-tumour barrier and the amount of vascularity may have an effect on the success of chemotherapy in brain tumours. (author)

Effects of Streptococcus sanguinis Bacteriocin on Cell Surface Hydrophobicity, Membrane Permeability, and Ultrastructure of Candida Thallus

Directory of Open Access Journals (Sweden)

Shengli Ma

2015-01-01

Full Text Available Candida albicans (C.a and Candida tropicalis (C.t were treated with Streptococcus sanguinis bacteriocin (S.s bacteriocin, respectively; the bacteriostatic dynamics of S.s bacteriocin, their effects on cell surface hydrophobicity, leakage of inorganic phosphorus and macromolecular substance, cytosolic calcium concentration, and ultrastructure changes of Candida thallus were detected and analyzed. The results showed that inhibitory effect of S.s bacteriocin on C.a and C.t reached peak level at 24 h, the cell-surface hydrophobicity decreased significantly (P < 0.05 after S.s bacteriocin treatment, and there was leakage of cytoplasmic inorganic phosphorus and macromolecular substance from C.a and C.t; cytosolic calcium concentration decreased greatly. After 24 h treatment by S.s bacteriocin, depressive deformity and defect could be found in the cell surface of C.a and C.t; the thallus displayed irregular forms: C.a was shrunken, there was unclear margins abutting upon cell wall and cell membrane, nucleus disappeared, and cytoplasm was inhomogeneous; likewise, C.t was first plasmolysis, and then the cytoplasm was shrunk, the ultrastructure of cell wall and cell membrane was continuously damaged, and the nucleus was karyolysis. It was illustrated that S.s bacteriocin had similar antifungal effect on C.a and C.t; their cell surface hydrophobicity, membrane permeability, and ultrastructure were changed significantly on exposure to S.s bacteriocin.

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; ...

Thermal Adaptation of the Archaeal and Bacterial Lipid Membranes

Science.gov (United States)

Koga, Yosuke

2012-01-01

The physiological characteristics that distinguish archaeal and bacterial lipids, as well as those that define thermophilic lipids, are discussed from three points of view that (1) the role of the chemical stability of lipids in the heat tolerance of thermophilic organisms: (2) the relevance of the increase in the proportion of certain lipids as the growth temperature increases: (3) the lipid bilayer membrane properties that enable membranes to function at high temperatures. It is concluded that no single, chemically stable lipid by itself was responsible for the adaptation of surviving at high temperatures. Lipid membranes that function effectively require the two properties of a high permeability barrier and a liquid crystalline state. Archaeal membranes realize these two properties throughout the whole biological temperature range by means of their isoprenoid chains. Bacterial membranes meet these requirements only at or just above the phase-transition temperature, and therefore their fatty acid composition must be elaborately regulated. A recent hypothesis sketched a scenario of the evolution of lipids in which the “lipid divide” emerged concomitantly with the differentiation of archaea and bacteria. The two modes of thermal adaptation were established concurrently with the “lipid divide.” PMID:22927779

Thermal Adaptation of the Archaeal and Bacterial Lipid Membranes

Directory of Open Access Journals (Sweden)

Yosuke Koga

2012-01-01

Full Text Available The physiological characteristics that distinguish archaeal and bacterial lipids, as well as those that define thermophilic lipids, are discussed from three points of view that (1 the role of the chemical stability of lipids in the heat tolerance of thermophilic organisms: (2 the relevance of the increase in the proportion of certain lipids as the growth temperature increases: (3 the lipid bilayer membrane properties that enable membranes to function at high temperatures. It is concluded that no single, chemically stable lipid by itself was responsible for the adaptation of surviving at high temperatures. Lipid membranes that function effectively require the two properties of a high permeability barrier and a liquid crystalline state. Archaeal membranes realize these two properties throughout the whole biological temperature range by means of their isoprenoid chains. Bacterial membranes meet these requirements only at or just above the phase-transition temperature, and therefore their fatty acid composition must be elaborately regulated. A recent hypothesis sketched a scenario of the evolution of lipids in which the “lipid divide” emerged concomitantly with the differentiation of archaea and bacteria. The two modes of thermal adaptation were established concurrently with the “lipid divide.”

REMOVAL OF ADDED NITRATE IN THE SINGLE, BINARY, AND TERNARY SYSTEMS OF COTTON BURR COMPOST, ZEROVALENT IRON, AND SEDIMENT: IMPLICATIONS FOR GROUNDWATER NITRATE REMEDIATION USING PERMEABLE REACTIVE BARRIERS

Science.gov (United States)

Recent research has shown that carbonaceous solid materials and zerovalent iron (Fe0) may potentially be used as media in permeable reactive barriers (PRBs) to degrade groundwater nitrate via heterotrophic denitrification in the solid carbon system, and via abiotic reduction and ...

Characterizing the Performance of Gas-Permeable Membranes as an Ammonia Recovery Strategy from Anaerobically Digested Dairy Manure.

Science.gov (United States)

Fillingham, Melanie; VanderZaag, Andrew; Singh, Jessica; Burtt, Stephen; Crolla, Anna; Kinsley, Chris; MacDonald, J Douglas

2017-10-07

Capturing ammonia from anaerobically digested manure could simultaneously decrease the adverse effects of ammonia inhibition on biogas production, reduce reactive nitrogen (N) loss to the environment, and produce mineral N fertilizer as a by-product. In this study, gas permeable membranes (GPM) were used to capture ammonia from dairy manure and digestate by the diffusion of gaseous ammonia across the membrane where ammonia is captured by diluted acid, forming an aqueous ammonium salt. A lab-scale prototype using tubular expanded polytetrafluoroethylene (ePTFE) GPM was used to (1) characterize the effect of total ammonium nitrogen (TAN) concentration, temperature, and pH on the ammonia capture rate using GPM, and (2) to evaluate the performance of a GPM system in conditions similar to a mesophilic anaerobic digester. The GPM captured ammonia at a rate between 2.2 to 6.3% of gaseous ammonia in the donor solution per day. Capture rate was faster in anaerobic digestate than raw manure. The ammonia capture rate could be predicted using non-linear regression based on the factors of total ammonium nitrogen concentration, temperature, and pH. This use of membranes shows promise in reducing the deleterious impacts of ammonia on both the efficiency of biogas production and the release of reactive N to the environment.

Inhibition of free radical scavenging enzymes affects mitochondrial membrane permeability transition during growth and aging of yeast cells.

Science.gov (United States)

Deryabina, Yulia; Isakova, Elena; Sekova, Varvara; Antipov, Alexey; Saris, Nils-Erik L

2014-12-01

In this study, we investigated the change in the antioxidant enzymes activity, cell respiration, reactive oxygen species (ROS), and impairment of membrane mitochondria permeability in the Endomyces magnusii yeasts during culture growth and aging. We showed that the transition into stationary phase is the key tool to understanding interaction of these processes. This growth stage is distinguished by two-fold increase in ROS production and respiration rate as compared to those in the logarithmic phase. It results in induction of alternative oxidase (AO) in the stationary phase, decline of the main antioxidant enzymes activities, ROS-production, and mitochondria membrane permeability. Significant increase in the share of mitochondrial isoform of superoxide dismutase (SOD2) occurred in the stationary phase from 51.8% (24 h of cultivation) to 68.6% (48 h of cultivation). Upon blocking the essential ROS-scavenging enzymes, SODs and catalases (CATs) some heterogeneity of cell population was observed: 80-90% of cells displayed evident signs of early apoptosis (such as disorientation of mitochondria cristae, mitochondrial fragmentation and deformation of nuclear chromatine). However, 10-20% of the population were definitely healthy. It allowed to draw the conclusion that a complete system of cell antioxidant protection underlies normal mitochondria functioning while the E. magnusii yeasts grow and age. Moreover, this system provides unimpaired cell physiology under oxidative stress during culture aging in the stationary phase. Failures in mitochondria functions due to inhibition of ROS-scavenging enzymes of CATs and SODs could lead to damage of the cells and some signs of early apoptosis.

Small-bowel permeability in collagenous colitis

DEFF Research Database (Denmark)

Wildt, Signe; Madsen, Jan L; Rumessen, Jüri J

2006-01-01

Collagenous colitis (CC) is a chronic inflammatory bowel disease that affects the colon. However, some patients with CC present with accompanying pathologic small-bowel manifestations such as coeliac disease, defects in bile acid absorption and histopathologic changes in small-intestinal biopsies......, indicating that CC is a pan-intestinal disease. In small-intestinal disease, the intestinal barrier function may be impaired, and the permeability of the small intestine altered. The purpose of this research was to study small-bowel function in patients with CC as expressed by intestinal permeability....

Reduction of methanol crossover by thin cracked metal barriers at the interface between membrane and electrode in direct methanol fuel cells

Science.gov (United States)

Kim, Sungjun; Jang, Segeun; Kim, Sang Moon; Ahn, Chi-Yeong; Hwang, Wonchan; Cho, Yong-Hun; Sung, Yung-Eun; Choi, Mansoo

2017-09-01

This work reports the successful reduction in methanol crossover by creating a thin cracked metal barrier at the interface between a Nafion® membrane and an electrode in direct methanol fuel cells (DMFCs). The cracks are generated by simple mechanical stretching of a metal deposited Nafion® membrane as a result of the elastic mismatch between the two attached surfaces. The cracked metal barriers with varying strains (∼0.5 and ∼1.0) are investigated and successfully incorporated into the DMFC. Remarkably, the membrane electrode assembly with the thin metal crack exhibits comparable ohmic resistance as well as reduction of methanol crossover, which enhanced the device performance.

Dewatering of Yoghurt Using Permeable Membrane and Acrylic Superabsorbent Hydrogel

Directory of Open Access Journals (Sweden)

A. Ahmadpour

2008-02-01

Full Text Available Conventional processes of food dewatering, such as thermal, have undesirable and destruction effects on vitamins, aromatic compounds and pigments. In addition, they are accompanied with some technological complications and energy consumption. Thus, food concentration processes are directed to non-thermal techniques or methods with reduced heat effects. Superabsorbents are highly hydrophilic polymer networks which can absorb water and aqueous solutions some hundred times of their weights and retain them. These materials are subgroups of hydrogel family that are transformed into gels after absorbing water. In the present research, the possibilities of yoghurt dewatering using superabsorbents have been investigated for the first time in Iran and some remarkable results are obtained for this vital product. In the experiments carried out to investigate the effect of these absorbents on normal method of yoghurt concentration (use of permeable membrane, type of bed (wide and vertical and time are also studied. The percentage of total soluble solids and dry solids of dewatered samples were measured in different time intervals up to 180 min. The results showed that superabsorbent on a wide bed would reduce the concentration time to one third. In other words, in a certain time interval, more than 70% increase in yoghurt dry solids was observed compared to normal method. These results show that acrylic superabsorbent hydrogel can be applied as highly hydrophilic material in non-thermal food dewatering methods.

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

Science.gov (United States)

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

2014-04-16

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