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Sample records for passive permeability barrier

  1. 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

  2. Developments in permeable and low permeability barriers

    International Nuclear Information System (INIS)

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

    1997-01-01

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

  3. Permeability Barrier Generation in the Martian Lithosphere

    Science.gov (United States)

    Schools, Joe; Montési, Laurent

    2015-11-01

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

  4. Therapeutic benefits of enhancing permeability barrier for atopic eczema

    Directory of Open Access Journals (Sweden)

    George Man

    2015-06-01

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

  5. Permeability criteria for effective function of passive countercurrent multiplier.

    Science.gov (United States)

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

    1996-01-01

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

  6. Herbal medicines that benefit epidermal permeability barrier function

    Directory of Open Access Journals (Sweden)

    Lizhi Hu

    2015-06-01

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

  7. 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.

  8. 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

  9. 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...

  10. Permeable reactive barriers for pollutant removal from groundwater

    International Nuclear Information System (INIS)

    Simon, F.G.; Meggyes, T.

    2001-01-01

    The removal of pollutants from the groundwater using permeable reactive barriers is a novel in-situ groundwater remediation technology. The most relevant decontamination processes used are chemical reduction, oxidation, precipitation and sorption, for which examples are given. Some common organic pollutants are halogenated hydrocarbons, aromatic and nitroaromatic compounds which can be treated in reactive barriers successfully. Lead, chromium and, in particular, uranium are dealt with in great detail among inorganic pollutants because of their occurrence in many European countries. Construction methods for cut-off walls and reactive barriers exhibit similar features. Apart from conventional methods, drilling, deep soil mixing, jet technology, arrays of wells, injected systems and biobarriers are applied to construct permeable reactive barriers. Permeable reactive barriers bear great potential for the future in remediation engineering. (orig.)

  11. 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

  12. 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....

  13. 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.

  14. 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.

  15. 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.

  16. 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.

  17. 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}.

  18. Fatty acids are required for epidermal permeability barrier function.

    Science.gov (United States)

    Mao-Qiang, M; Elias, P M; Feingold, K R

    1993-08-01

    The permeability barrier is mediated by a mixture of ceramides, sterols, and free fatty acids arranged as extracellular lamellar bilayers in the stratum corneum. Whereas prior studies have shown that cholesterol and ceramides are required for normal barrier function, definitive evidence for the importance of nonessential fatty acids is not available. To determine whether epidermal fatty acid synthesis also is required for barrier homeostasis, we applied 5-(tetradecyloxy)-2-furancarboxylic acid (TOFA), an inhibitor of acetyl CoA carboxylase, after disruption of the barrier by acetone or tape stripping. TOFA inhibits epidermal fatty acid by approximately 50% and significantly delays barrier recovery. Moreover, coadministration of palmitate with TOFA normalizes barrier recovery, indicating that the delay is due to a deficiency in bulk fatty acids. Furthermore, TOFA treatment also delays the return of lipids to the stratum corneum and results in abnormalities in the structure of lamellar bodies, the organelle which delivers lipid to the stratum corneum. In addition, the organization of secreted lamellar body material into lamellar bilayers within the stratum corneum interstices is disrupted by TOFA treatment. Finally, these abnormalities in lamellar body and stratum corneum membrane structure are corrected by coapplication of palmitate with TOFA. These results demonstrate a requirement for bulk fatty acids in barrier homeostasis. Thus, inhibiting the epidermal synthesis of any of the three key lipids that form the extracellular, lipid-enriched membranes of the stratum corneum results in an impairment in barrier homeostasis.

  19. 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

  20. Passive Resonant Bidirectional Converter with Galvanic Barrier

    Science.gov (United States)

    Rosenblad, Nathan S. (Inventor)

    2014-01-01

    A passive resonant bidirectional converter system that transports energy across a galvanic barrier includes a converter using at least first and second converter sections, each section including a pair of transfer terminals, a center tapped winding; a chopper circuit interconnected between the center tapped winding and one of the transfer terminals; an inductance feed winding interconnected between the other of the transfer terminals and the center tap and a resonant tank circuit including at least the inductance of the center tap winding and the parasitic capacitance of the chopper circuit for operating the converter section at resonance; the center tapped windings of the first and second converter sections being disposed on a first common winding core and the inductance feed windings of the first and second converter sections being disposed on a second common winding core for automatically synchronizing the resonant oscillation of the first and second converter sections and transferring energy between the converter sections until the voltage across the pairs of transfer terminals achieves the turns ratio of the center tapped windings.

  1. 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...

  2. 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

  3. Engineered passive bioreactive barriers: risk-managing the legacy of industrial soil and groundwater pollution.

    Science.gov (United States)

    Kalin, Robert M

    2004-06-01

    Permeable reactive barriers are a technology that is one decade old, with most full-scale applications based on abiotic mechanisms. Though there is extensive literature on engineered bioreactors, natural biodegradation potential, and in situ remediation, it is only recently that engineered passive bioreactive barrier technology is being considered at the commercial scale to manage contaminated soil and groundwater risks. Recent full-scale studies are providing the scientific confidence in our understanding of coupled microbial (and genetic), hydrogeologic, and geochemical processes in this approach and have highlighted the need to further integrate engineering and science tools.

  4. 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

  5. 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

  6. Chances and barriers for passive house renovations

    NARCIS (Netherlands)

    Mlecnik, E.; Opstelten, I.; Rovers, R.; Verdeyen, N.; Wagenaar, A.

    2016-01-01

    There is significant potential for carbon reduction and energy saving in residential buildings. Various market actors are looking for ways to increase the uptake of passive house renovation and its certification.
    This study aimed specifically to draw lessons from research projects towards the

  7. 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.

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

    International Nuclear Information System (INIS)

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

    1985-01-01

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

  9. 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

  10. 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...

  11. 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.

  12. [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.

  13. Redox-active media for permeable reactive barriers

    International Nuclear Information System (INIS)

    Sivavec, T.M.; Mackenzie, P.D.; Horney, D.P.; Baghel, S.S.

    1997-01-01

    In this paper, three classes of redox-active media are described and evaluated in terms of their long-term effectiveness in treating TCE-contaminated groundwater in permeable reactive zones. Zero-valent iron, in the form of recycled cast iron filings, the first class, has received considerable attention as a reactive media and has been used in about a dozen pilot- and full-scale subsurface wall installations. Criteria used in selecting commercial sources of granular iron, will be discussed. Two other classes of redox-active media that have not yet seen wide use in pilot- or full-scale installations will also be described: Fe(II) minerals and bimetallic systems. Fe(II) minerals, including magnetite (Fe 3 O 4 ), and ferrous sulfide (troilite, FeS), are redox-active and afford TCE reduction rates and product distributions that suggest that they react via a reductive mechanism similar to that which operates in the FeO system. Fe(II) species within the passive oxide layer coating the iron metal may act as electron transfer mediators, with FeO serving as the bulk reductant. Bimetallic systems, the third class of redox-active media, are commonly prepared by plating a second metal onto zero-valent iron (e.g., Ni/Fe and Pd/Fe) and have been shown to accelerate solvent degradation rates relative to untreated iron metal. The long-term effectiveness of this approach, however, has not yet been determined in groundwater treatability tests. The results of a Ni-plated iron column study using site groundwater indicate that a change in reduction mechanism (to catalytic dehydrohalogenation/hydrogenation) accounts for the observed rate enhancement. A significant loss in media reactivity was observed over time, attributable to Ni catalyst deactivation or poisoning. Zero-valent iron systems have not shown similar losses in reactivity in long-term laboratory, pilot or field investigations

  14. 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...

  15. Permeable reactive barrier - innovative technology for ground-water remediation

    International Nuclear Information System (INIS)

    Vidic, D.R.

    2002-01-01

    Significant advances in the application of permeable reactive barriers (PRBs) for ground-water remediation have been witnessed in the last 5 years. From only a few full-scale systems and pilot-scale demonstrations, there are currently at least 38 full-scale PRBs using zero-valent iron (ZVI) as a reactive material. Of those, 26 are continuous reactive walls, 9 are funnel-and- gate systems and 3 are in situ reactive vessels. Most of the PRB systems have used granular iron media and have been applied to address the control of contamination caused by chlorinated volatile organic compounds or heavy metals. Many regulatory agencies have expressed interest in PRB systems and are becoming more comfortable in issuing permits. The main advantage of PRB systems is that the installation costs are comparable with those of other ground-water remediation technologies, while the O and M costs are significantly lower and are mostly due to monitoring requirements, which are required for all remediation approaches. In addition, the land use can resume after the installation of the PRB systems, since there are few visible signs of the installation above grounds except for the monitoring wells. It is difficult to make any definite conclusions about the long-term performance of PRB systems because there is no more than 5 years of the record of performance that can be used for such analysis. The two main challenges still facing this technology are: (1) evaluating the longevity (geochemistry) of a PRB; and (2) ensuring/verifying hydraulic performance. A number of public/private partnerships have been established in recent years that are working together to resolve some of these problems. This organized approach by combining the efforts of several government agencies and private companies will likely result in better understanding and, hopefully, better acceptance of this technology in the future. (author)

  16. 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

  17. 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...

  18. 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...

  19. 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

  20. 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)

  1. Do the recommended standards for in vitro biopharmaceutic classification of drug permeability meet the "passive transport" criterion for biowaivers?

    Science.gov (United States)

    Žakelj, Simon; Berginc, Katja; Roškar, Robert; Kraljič, Bor; Kristl, Albin

    2013-01-01

    BCS based biowaivers are recognized by major regulatory agencies. An application for a biowaiver can be supported by or even based on "in vitro" measurements of drug permeability. However, guidelines limit the application of biowaivers to drug substances that are transported only by passive mechanisms. Regarding published permeability data as well as measurements obtained in our institution, one can rarely observe drug substances that conform to this very strict criterion. Therefore, we measured the apparent permeability coefficients of 13 drugs recommended by FDA's Guidance to be used as standards for "in vitro" permeability classification. The asymmetry of permeability data determined for both directions (mucosal-to-serosal and serosalto- mucosal) through the rat small intestine revealed significant active transport for four out of the nine high-permeability standards and for all four low-permeability standard drugs. As could be expected, this asymmetry was abolished at 4°C on rat intestine. The permeability of all nine high-permeability, but none of the low permeability standards, was also much lower when measured with intestinal tissue, Caco-2 cell monolayers or artificial membranes at 4°C compared to standard conditions (37°C). Additionally, concurrent testing of several standard drugs revealed that membrane transport can be affected by the use of internal permeability standards. The implications of the results are discussed regarding the regulatory aspects of biopharmaceutical classification, good practice in drug permeability evaluation and regarding the general relevance of transport proteins with broad specificity in drug absorption.

  2. 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

  3. 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.

  4. Caractérisation de la perméabilité des couches constituant la barrière passive des installations de stockage de déchets non dangereux Permeability characterization of the geological barrier of non dangerous landfill sites

    Directory of Open Access Journals (Sweden)

    Mouthier B.

    2012-09-01

    Full Text Available Pour obtenir son autorisation d’exploiter, une Installation de Stockage de Déchets Non Dangereux (ISDND doit justifier réglementairement sa favorabilité géologique. Le « Guide de bonnes pratiques pour les reconnaissances géologiques » de l’AFNOR fournit les critères d’aptitude du site à recevoir une ISDND et les moyens à mettre en œuvre, dont ceux qui concernent la perméabilité des couches géologiques qui protègent le milieu naturel. La mesure de la perméabilité in situ, en forage, des matériaux peu à très peu perméables des deux couches de la barrière de sécurité passive, est une opération délicate qui nécessite une mise en œuvre soignée respectant les normes appropriées, choisies en fonction des gammes de perméabilité attendues. Plusieurs types d’essai en forage sont présentés. In order to get administrative authorization, a non dangerous waste landfill site (ISDND, must justify a favourable geological context, which follows the AFNOR “Guide de bonnes pratiques pour les reconnaissances géologiques ». Criteria and technical means are described among which the in situ and lab permeability determination processes. The low and very low permeability coefficient to be measured within the deep argillaceous formations of a landfill site, is a delicate operation which must be representative and accurate. Depending the permeability range, several norms are proposed.

  5. 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...

  6. Effects of topical application of aqueous solutions of hexoses on epidermal permeability barrier recovery rate after barrier disruption.

    Science.gov (United States)

    Denda, Mitsuhiro

    2011-11-01

    Previous studies have suggested that hexose molecules influence the stability of phospholipid bilayers. Therefore, the effects of topical application of all 12 stereoisomers of dextro-hexose on the epidermal barrier recovery rate after barrier disruption were evaluated. Immediately after tape stripping, 0.1 m aqueous solution of each hexose was applied on hairless mouse skin. Among the eight dextro-aldohexoses, topical application of altose, idose, mannose and talose accelerated the barrier recovery, while allose, galactose, glucose and gulose had no effect. Among the four dextro-ketohexoses, psicose, fructose, sorbose and tagatose all accelerated the barrier recovery. As the effects of hexoses on the barrier recovery rate appeared within 1 h, the mechanism is unlikely to be genomic. Instead, these hexoses may influence phase transition of the lipid bilayers of lamellar bodies and cell membrane, a crucial step in epidermal permeability barrier homeostasis. © 2011 John Wiley & Sons A/S.

  7. Development of Permeable Reactive Barriers (PRB) Using Edible Oils

    Science.gov (United States)

    2008-06-01

    naturally occurring processes of advection and dispersion to bring the contaminants to the treatment barrier. A large scale approach would be to form a...process has been developed for distributing soybean oil as an oil-in-water emulsion consisting of small oil droplets dispersed in a continuous...Thiele Kaolin Company, Sandersville, Georgia) was added to certain materials to evaluate the effect of increasing clay content. Grain size

  8. 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

  9. Permeability Barrier and Microstructure of Skin Lipid Membrane Models of Impaired Glucosylceramide Processing

    OpenAIRE

    Sochorov?, Michaela; Sta?kov?, Kl?ra; Pullmannov?, Petra; Kov??ik, Andrej; Zbytovsk?, Jarmila; V?vrov?, Kate?ina

    2017-01-01

    Ceramide (Cer) release from glucosylceramides (GlcCer) is critical for the formation of the skin permeability barrier. Changes in ?-glucocerebrosidase (GlcCer?ase) activity lead to diminished Cer, GlcCer accumulation and structural defects in SC lipid lamellae; however, the molecular basis for this impairment is not clear. We investigated impaired GlcCer-to-Cer processing in human Cer membranes to determine the physicochemical properties responsible for the barrier defects. Minor impairment (...

  10. 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.

  11. 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.

  12. Treatment of fue diesel with a permeable reactive barrier technology

    Directory of Open Access Journals (Sweden)

    SANTIAGO ALONSO CARDONA GALLO

    2007-01-01

    Full Text Available La investigación estudió el tratamiento de diesel combustibles de producción mexicana contenidos en agua con un sistema de barrera reactiva permeables a escala de laboratorio (siete columnas. Se uso un suelo agrícola como medio reactivo. Se aplico peroxido de hidrógeno al 50% industrial como fuente de oxigeno y nitrógeno en urea al 46% como nutriente. Se caracterizo el medio reactivo con los principales parámetros de interés (humedad, materia orgánica, pH, nitrógeno total, fósforo disponible, clasificación del suelo, conductividad eléctrica, sólidos suspendidos volátiles, densidad real y aparente, porosidad, textura, color, salinidad, conductividad hidráulica, capacidad de campo y densidad de bacterias. Se determinaron las cinéticas de degradación y la capacidad de adsorción del diesel en el medio reactivo. Las barreras reactivas permeables se diseñaron con los resultados cinéticos obtenidos en los reactores por lotes. Las columnas tenían dimensiones de 30 cm de longitud y 10 cm de diámetro. Las cinéticas de determinaron durante 18 días y las columnas se corrieron durante 70 días presentando remociones arriba del 80%. Se usaron concentraciones iniciales de diesel de 15,000 mg/L. Para la modelación de la adsorción se aplicaron las ecuaciones de Freundlich y Langmuir, donde esta ultima presentó un mejor ajuste a los datos a los datos experimentales y una mayor capacidad de adsorción. Para el suministro de los nutrientes y oxigeno se aplico el modelo propuesto por McCarty y la ecuación media para diesel propuesta por Jackson. Se determinó una velocidad de degradación de 0.0908 d-1, un coeficiente de distribución del diesel en el medio reactivo de 0.8 ml/g, una capacidad de adsorción de diesel en el medio reactivo de 13.50 mg/L y un factor de retardo de 3.69

  13. 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

  14. 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 ...

  15. 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

  16. 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;

  17. 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

  18. Passive water and urea permeability of a human Na(+)-glutamate cotransporter expressed in Xenopus oocytes

    DEFF Research Database (Denmark)

    Macaulay, Nanna; Gether, Ulrik; Klærke, Dan Arne

    2002-01-01

    to the K(0.5) value for glutamate activation of transport. The specific inhibitor DL-threo-beta-benzyloxyaspartate (TBOA) reduced the EAAT1-specific L(p) to 72 %. EAAT1 supported passive fluxes of [(14)C]urea and [(14)C]glycerol. The [(14)C]urea flux was increased in the presence of glutamate. The data...... suggest that the permeability depends on the conformational equilibrium of the EAAT1. At positive potentials and in the presence of Na(+) and glutamate, the pore is enlarged and water and urea penetrate more readily. The L(p) was larger when measured with urea or glycerol as osmolytes as compared...... with mannitol. Apparently, the properties of the pore are not uniform along its length. The outer section may accommodate urea and glycerol in an osmotically active form, giving rise to larger water fluxes. The physiological role of EAAT1 for water homeostasis in the central nervous system is discussed....

  19. 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

  20. Passive advection-dispersion in networks of pipes: Effect of connectivity and relationship to permeability

    Science.gov (United States)

    Bernabé, Y.; Wang, Y.; Qi, T.; Li, M.

    2016-02-01

    The main purpose of this work is to investigate the relationship between passive advection-dispersion and permeability in porous materials presumed to be statistically homogeneous at scales larger than the pore scale but smaller than the reservoir scale. We simulated fluid flow through pipe network realizations with different pipe radius distributions and different levels of connectivity. The flow simulations used periodic boundary conditions, allowing monitoring of the advective motion of solute particles in a large periodic array of identical network realizations. In order to simulate dispersion, we assumed that the solute particles obeyed Taylor dispersion in individual pipes. When a particle entered a pipe, a residence time consistent with local Taylor dispersion was randomly assigned to it. When exiting the pipe, the particle randomly proceeded into one of the pipes connected to the original one according to probabilities proportional to the outgoing volumetric flow in each pipe. For each simulation we tracked the motion of at least 6000 solute particles. The mean fluid velocity was 10-3 ms-1, and the distance traveled was on the order of 10 m. Macroscopic dispersion was quantified using the method of moments. Despite differences arising from using different types of lattices (simple cubic, body-centered cubic, and face-centered cubic), a number of general observations were made. Longitudinal dispersion was at least 1 order of magnitude greater than transverse dispersion, and both strongly increased with decreasing pore connectivity and/or pore size variability. In conditions of variable hydraulic radius and fixed pore connectivity and pore size variability, the simulated dispersivities increased as power laws of the hydraulic radius and, consequently, of permeability, in agreement with previously published experimental results. Based on these observations, we were able to resolve some of the complexity of the relationship between dispersivity and permeability.

  1. 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

  2. Scaffolding proteins in the development and maintenance of the epidermal permeability barrier.

    Science.gov (United States)

    Crawford, Melissa; Dagnino, Lina

    2017-10-02

    The skin of mammals and other terrestrial vertebrates protects the organism against the external environment, preventing heat, water and electrolyte loss, as well as entry of chemicals and pathogens. Impairments in the epidermal permeability barrier function are associated with the genesis and/or progression of a variety of pathological conditions, including genetic inflammatory diseases, microbial and viral infections, and photodamage induced by UV radiation. In mammals, the outside-in epidermal permeability barrier is provided by the joint action of the outermost cornified layer, together with assembled tight junctions in granular keratinocytes found in the layers underneath. Tight junctions serve as both outside-in and inside-out barriers, and impede paracellular movements of ions, water, macromolecules and microorganisms. At the molecular level, tight junctions consist of integral membrane proteins that form an extracellular seal between adjacent cells, and associate with cytoplasmic scaffold proteins that serve as links with the actin cytoskeleton. In this review, we address the roles that scaffold proteins play specifically in the establishment and maintenance of the epidermal permeability barrier, and how various pathologies alter or impair their functions.

  3. The role of multidrug resistance protein (MRP-1) as an active efflux transporter on blood-brain barrier (BBB) permeability.

    Science.gov (United States)

    Lingineni, Karthik; Belekar, Vilas; Tangadpalliwar, Sujit R; Garg, Prabha

    2017-05-01

    Drugs acting on central nervous system (CNS) may take longer duration to reach the market as these compounds have a higher attrition rate in clinical trials due to the complexity of the brain, side effects, and poor blood-brain barrier (BBB) permeability compared to non-CNS-acting compounds. The roles of active efflux transporters with BBB are still unclear. The aim of the present work was to develop a predictive model for BBB permeability that includes the MRP-1 transporter, which is considered as an active efflux transporter. A support vector machine model was developed for the classification of MRP-1 substrates and non-substrates, which was validated with an external data set and Y-randomization method. An artificial neural network model has been developed to evaluate the role of MRP-1 on BBB permeation. A total of nine descriptors were selected, which included molecular weight, topological polar surface area, ClogP, number of hydrogen bond donors, number of hydrogen bond acceptors, number of rotatable bonds, P-gp, BCRP, and MRP-1 substrate probabilities for model development. We identified 5 molecules that fulfilled all criteria required for passive permeation of BBB, but they all have a low logBB value, which suggested that the molecules were effluxed by the MRP-1 transporter.

  4. 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.

  5. 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

  6. 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

  7. 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.

  8. /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

  9. 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....

  10. 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.

  11. 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.

  12. 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

  13. 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

  14. 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

  15. The Blood-Brain Barrier Permeability of Six Indole Alkaloids from Uncariae Ramulus Cum Uncis in the MDCK-pHaMDR Cell Monolayer Model

    Directory of Open Access Journals (Sweden)

    Yi-Nan Zhang

    2017-11-01

    Full Text Available Uncariae Ramulus Cum Uncis (URCU is a widely used traditional Chinese medicine, and is reported to have various central nervous system effects. Alkaloids have been demonstrated to be the predominant pharmacological active components of URCU. In order to evaluate the blood-brain barrier (BBB permeability and transport mechanism of six typical indole alkaloids from URCU, the MDCK-pHaMDR cell monolayer model was used as an in vitro surrogate model for BBB. The samples were analyzed by high-performance liquid chromatography, and the apparent permeability coefficients (Papp were calculated. Among the six alkaloids, isorhynchophylline (2, isocorynoxeine (4, hirsutine (5 and hirsuteine (6 showed high permeability, with Papp values at 10−5 cm/s level in bidirectional transport. For rhynchophylline (1 and corynoxeine (3, they showed moderate permeability, with Papp values from the apical (AP side to the basolateral (BL side at 10−6 cm/s level and efflux ratio (Papp BL→AP/Papp AP→BL above 2. The time- and concentration-dependency experiments indicated that the main mechanism for 2, 4, 5 and 6 through BBB was passive diffusion. The efflux mechanism involved in the transports of compounds 1 and 3 could be reduced significantly by verapamil, and molecular docking screening also showed that 1 and 3 had strong bindings to P-glycoprotein. This study provides useful information for predicting the BBB permeability for 1–6, as well as better understanding of their central nervous system pharmacological activities.

  16. 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.

  17. Role of lipids in the formation and maintenance of the cutaneous permeability barrier.

    Science.gov (United States)

    Feingold, Kenneth R; Elias, Peter M

    2014-03-01

    The major function of the skin is to form a barrier between the internal milieu and the hostile external environment. A permeability barrier that prevents the loss of water and electrolytes is essential for life on land. The permeability barrier is mediated primarily by lipid enriched lamellar membranes that are localized to the extracellular spaces of the stratum corneum. These lipid enriched membranes have a unique structure and contain approximately 50% ceramides, 25% cholesterol, and 15% free fatty acids with very little phospholipid. Lamellar bodies, which are formed during the differentiation of keratinocytes, play a key role in delivering the lipids from the stratum granulosum cells into the extracellular spaces of the stratum corneum. Lamellar bodies contain predominantly glucosylceramides, phospholipids, and cholesterol and following the exocytosis of lamellar lipids into the extracellular space of the stratum corneum these precursor lipids are converted by beta glucocerebrosidase and phospholipases into the ceramides and fatty acids, which comprise the lamellar membranes. The lipids required for lamellar body formation are derived from de novo synthesis by keratinocytes and from extra-cutaneous sources. The lipid synthetic pathways and the regulation of these pathways are described in this review. In addition, the pathways for the uptake of extra-cutaneous lipids into keratinocytes are discussed. This article is part of a Special Issue entitled The Important Role of Lipids in the Epidermis and their Role in the Formation and Maintenance of the Cutaneous Barrier. Guest Editors: Kenneth R. Feingold and Peter Elias. Published by Elsevier B.V.

  18. 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.

  19. 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.

  20. 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

  1. 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....

  2. 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...

  3. 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.

  4. 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.

  5. 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.

  6. 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

  7. 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.

  8. 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

  9. 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.

  10. 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.

  11. 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...

  12. 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.

  13. 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

  14. 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)

  15. 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.

  16. 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.)

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

    Directory of Open Access Journals (Sweden)

    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.

  18. 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.

  19. 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)

  20. 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

  1. Passive Barriers to Inadvertent Human Intrusion for Use at the Nevada Test Site

    International Nuclear Information System (INIS)

    NSTec Environmental Management

    2007-01-01

    In July1996, BN transmitted Passive Barriers to Inadvertent Human Intrusion for Use at the Nevada Test Site to the United States Department of Energy, under Contract DE-AC08-91NV10833. The 1996 paper had a limited distribution and was not reviewed for public release. In 2007, National Security Technologies LLC (NSTec) made minor revisions to conform to current editorial standards of the NNSA/NSO and to meet current security requirements for public release. The primary purpose of this study was to identify types of engineered passive barriers that could deter future intrusion into buried low-level radioactive waste, particularly intrusion by drilling water wells. The study considered drilling technology, many natural and man-made materials, and both underground and above-ground barriers. Based on cost and effectiveness, the report recommended underground barriers consisting of a layer of rubble or tires. An aboveground barrier mound might also prove effective, but would cost more, and may become an attractive nuisance (e.g., might, after their purpose has been forgotten, encourage exploration for the sake of satisfying curiosity). Advances in drilling technology could render any engineered barriers ineffective if there is motivation to penetrate the barriers

  2. 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...

  3. 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...

  4. 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...

  5. 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

  6. Transcranial direct current stimulation transiently increases the blood-brain barrier solute permeability in vivo

    Science.gov (United States)

    Shin, Da Wi; Khadka, Niranjan; Fan, Jie; Bikson, Marom; Fu, Bingmei M.

    2016-03-01

    Transcranial Direct Current Stimulation (tDCS) is a non-invasive electrical stimulation technique investigated for a broad range of medical and performance indications. Whereas prior studies have focused exclusively on direct neuron polarization, our hypothesis is that tDCS directly modulates endothelial cells leading to transient changes in blood-brain-barrier (BBB) permeability (P) that are highly meaningful for neuronal activity. For this, we developed state-of-the-art imaging and animal models to quantify P to various sized solutes after tDCS treatment. tDCS was administered using a constant current stimulator to deliver a 1mA current to the right frontal cortex of rat (approximately 2 mm posterior to bregma and 2 mm right to sagittal suture) to obtain similar physiological outcome as that in the human tDCS application studies. Sodium fluorescein (MW=376), or FITC-dextrans (20K and 70K), in 1% BSA mammalian Ringer was injected into the rat (SD, 250-300g) cerebral circulation via the ipsilateral carotid artery by a syringe pump at a constant rate of ~3 ml/min. To determine P, multiphoton microscopy with 800-850 nm wavelength laser was applied to take the images from the region of interest (ROI) with proper microvessels, which are 100-200 micron below the pia mater. It shows that the relative increase in P is about 8-fold for small solute, sodium fluorescein, ~35-fold for both intermediate sized (Dex-20k) and large (Dex-70k) solutes, 10 min after 20 min tDCS pretreatment. All of the increased permeability returns to the control after 20 min post treatment. The results confirmed our hypothesis.

  7. 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.

  8. Evaluation of a permeable reactive barrier technology for use at Rocky Flats Environmental Technology Site (RFETS)

    International Nuclear Information System (INIS)

    Dwyer, Brian P.

    2000-01-01

    Three reactive materials were evaluated at laboratory scale to identify the optimum treatment reagent for use in a Permeable Reactive Barrier Treatment System at Rocky Flats Environmental Technology Site (RFETS). The contaminants of concern (COCS) are uranium, TCE, PCE, carbon tetrachloride, americium, and vinyl chloride. The three reactive media evaluated included high carbon steel iron filings, an iron-silica alloy in the form of a foam aggregate, and a peculiar humic acid based sorbent (Humasorb from Arctech) mixed with sand. Each material was tested in the laboratory at column scale using simulated site water. All three materials showed promise for the 903 Mound Site however, the iron filings were determined to be the least expensive media. In order to validate the laboratory results, the iron filings were further tested at a pilot scale (field columns) using actual site water. Pilot test results were similar to laboratory results; consequently, the iron filings were chosen for the fill-scale demonstration of the reactive barrier technology. Additional design parameters including saturated hydraulic conductivity, treatment residence time, and head loss across the media were also determined and provided to the design team in support of the final design. The final design was completed by the Corps of Engineers in 1997 and the system was constructed in the summer of 1998. The treatment system began fill operation in December, 1998 and despite a few problems has been operational since. Results to date are consistent with the lab and pilot scale findings, i.e., complete removal of the contaminants of concern (COCs) prior to discharge to meet RFETS cleanup requirements. Furthermore, it is fair to say at this point in time that laboratory developed design parameters for the reactive barrier technology are sufficient for fuel scale design; however,the treatment system longevity and the long-term fate of the contaminants are questions that remain unanswered. This

  9. Passive permeability of salicylic acid in renal proximal S2 and S3 tubules

    International Nuclear Information System (INIS)

    Chatton, J.Y.; Roch-Ramel, F.

    1991-01-01

    The role of nonionic diffusion in the transport of salicylic acid across rabbit proximal S2 and S3 segments was investigated using the in vitro isolated perfused tubule technique. The [ 14 C] salicylic acid apparent reabsorptive permeability (P'I-b, 10(-5) cm/s) was measured at 19 degrees C with luminal solutions kept at different pH and bath maintained at pH 7.4. In S2 tubules, P'I-b was 25.0 +/- 3.5 when luminal pH was 6.0; P'I-b decreased to 8.1 +/- 1.4 and to 4.4 +/- 1.2 at a luminal pH of 6.5 and 7.0, respectively. In S3 tubules, P'I-b was 17.6 +/- 2.4, 5.3 +/- 1.1 and 3.4 +/- 1.1 at a luminal pH of 6.0, 6.5 and 7.0, respectively. There was a close correlation between P'I-b and the calculated proportion of nonionized salicylic acid present at each pH, indicating that only the nonionized molecule could diffuse in our conditions. We calculated the apparent permeability of nonionic salicylic acid and found 0.248 +/- 0.032 cm/s for S2 and 0.176 +/- 0.022 cm/s for S3 tubules. These calculated permeabilities were independent of pH

  10. Assessment of a Hydroxyapatite Permeable Reactive Barrier to Remediate Uranium at the Old Rifle Site Colorado

    International Nuclear Information System (INIS)

    Moore, Robert C.; Szecsody, James; Rigali, Mark J.; Vermuel, Vince; Leullen, Jon

    2016-01-01

    We have performed an initial evaluation and testing program to assess the effectiveness of a hydroxyapatite (Ca10(PO4)6(OH)2) permeable reactive barrier and source area treatment to decrease uranium mobility at the Department of Energy (DOE) former Old Rifle uranium mill processing site in Rifle, western Colorado. Uranium ore was processed at the site from the 1940s to the 1970s. The mill facilities at the site as well as the uranium mill tailings previously stored there have all been removed. Groundwater in the alluvial aquifer beneath the site still contains elevated concentrations of uranium, and is currently used for field tests to study uranium behavior in groundwater and investigate potential uranium remediation technologies. The technology investigated in this work is based on in situ formation of apatite in sediment to create a subsurface apatite PRB and also for source area treatment. The process is based on injecting a solution containing calcium citrate and sodium into the subsurface for constructing the PRB within the uranium plume. As the indigenous sediment micro-organisms biodegrade the injected citrate, the calcium is released and reacts with the phosphate to form hydroxyapatite (precipitate). This paper reports on proof-of-principle column tests with Old Rifle sediment and synthetic groundwater.

  11. Assessment of a Hydroxyapatite Permeable Reactive Barrier to Remediate Uranium at the Old Rifle Site Colorado.

    Energy Technology Data Exchange (ETDEWEB)

    Moore, Robert C.; Szecsody, James (PNNL); Rigali, Mark J.; Vermuel, Vince (PNNL); Leullen, Jon (AECOM)

    2016-02-01

    We have performed an initial evaluation and testing program to assess the effectiveness of a hydroxyapatite (Ca10(PO4)6(OH)2) permeable reactive barrier and source area treatment to decrease uranium mobility at the Department of Energy (DOE) former Old Rifle uranium mill processing site in Rifle, western Colorado. Uranium ore was processed at the site from the 1940s to the 1970s. The mill facilities at the site as well as the uranium mill tailings previously stored there have all been removed. Groundwater in the alluvial aquifer beneath the site still contains elevated concentrations of uranium, and is currently used for field tests to study uranium behavior in groundwater and investigate potential uranium remediation technologies. The technology investigated in this work is based on in situ formation of apatite in sediment to create a subsurface apatite PRB and also for source area treatment. The process is based on injecting a solution containing calcium citrate and sodium into the subsurface for constructing the PRB within the uranium plume. As the indigenous sediment micro-organisms biodegrade the injected citrate, the calcium is released and reacts with the phosphate to form hydroxyapatite (precipitate). This paper reports on proof-of-principle column tests with Old Rifle sediment and synthetic groundwater.

  12. 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

  13. Assessment of solid reactive mixtures for the development of biological permeable reactive barriers

    International Nuclear Information System (INIS)

    Pagnanelli, Francesca; Viggi, Carolina Cruz; Mainelli, Sara; Toro, Luigi

    2009-01-01

    Solid reactive mixtures were tested as filling material for the development of biological permeable reactive barriers for the treatment of heavy metals contaminated waters. Mixture selection was performed by taking into account the different mechanisms operating in sulphate and cadmium removal with particular attention to bioprecipitation and sorption onto the organic matrices in the mixtures. Suspensions of eight reactive mixtures were tested for sulphate removal (initial concentration 3 g L -1 ). Each mixture was made up of four main functional components: a mix of organic sources for bacterial growth, a neutralizing agent, a porous medium and zero-valent iron. The best mixture among the tested ones (M8: 6% leaves, 9% compost, 3% zero-valent iron, 30% silica sand, 30% perlite, 22% limestone) presented optimal conditions for SRB growth (pH 7.8 ± 0.1; E h = -410 ± 5 mV) and 83% sulphate removal in 22 days (25% due to bioreduction, 32% due to sorption onto compost and 20% onto leaves). M8 mixture allowed the complete abatement of cadmium with a significant contribution of sorption over bioprecipitation (6% Cd removal due to SRB activity). Sorption properties, characterised by potentiometric titrations and related modelling, were mainly due to carboxylic sites of organic components used in reactive mixtures.

  14. Laboratory study on sequenced permeable reactive barrier remediation for landfill leachate-contaminated groundwater

    International Nuclear Information System (INIS)

    Dong Jun; Zhao Yongsheng; Zhang Weihong; Hong Mei

    2009-01-01

    Permeable reactive barrier (PRB) was a promising technology for groundwater remediation. Landfill leachate-polluted groundwater riches in various hazardous contaminants. Two lab-scale reactors (reactors A and B) were designed for studying the feasibility of PRB to remedy the landfill leachate-polluted groundwater. Zero valent iron (ZVI) and the mixture of ZVI and zeolites constitute the first section of the reactors A and B, respectively; the second section of two reactors consists of oxygen releasing compounds (ORCs). Experimental results indicated that BOD 5 /COD increased from initial 0.32 up to average 0.61 and 0.6 through reactors A and B, respectively. Removal efficiency of mixed media for pollutants was higher than that of single media (ZVI only). Zeolites exhibited selective removal of Zn, Mn, Mg, Cd, Sr, and NH 4 + , and removal efficiency was 97.2%, 99.6%, 95.9%, 90.5% and 97.4%, respectively. The maximum DO concentration of reactors A and B were 7.64 and 6.78 mg/L, respectively, while the water flowed through the ORC. Therefore, sequenced PRB system was effective and was proposed as an alternative method to remedy polluted groundwater by landfill leachate

  15. Evaluation of five strategies to limit the impact of fouling in permeable reactive barriers

    International Nuclear Information System (INIS)

    Li Lin; Benson, Craig H.

    2010-01-01

    Ground water flow and geochemical reactive transport models were used to assess the effectiveness of five strategies used to limit fouling and to enhance the long-term hydraulic behavior of continuous-wall permeable reactive barriers (PRBs) employing granular zero valent iron (ZVI). The flow model accounted for geological heterogeneity and the reactive transport model included a geochemical algorithm for simulating iron corrosion and mineral precipitation reactions that have been observed in ZVI PRBs. The five strategies that were evaluated are pea gravel equalization zones, a sacrificial pre-treatment zone, pH adjustment, large ZVI particles, and mechanical treatment. Results of simulations show that installation of pea gravel equalization zones results in flow equalization and a more uniform distribution of residence times within the PRB. Residence times within the PRB are less affected by mineral precipitation when a pre-treatment zone is employed. pH adjustment limits the total amount of hydroxide ions in ground water to reduce porosity reduction and to retain larger residence times. Larger ZVI particles reduce porosity reduction as a result of the smaller iron surface area for iron corrosion, and retain longer residence time. Mechanical treatment redistributes the porosity uniformly throughout the PRB over time, which is effective in maintaining residence time.

  16. Design, installation, and performance of a multi-layered permeable reactive barrier, Los Alamos National Laboratory

    International Nuclear Information System (INIS)

    Kaszuba, John P.; Longmire, Patrick A.; Strietelmeier, Elizabeth A.; Taylor, Tammy P.; Den-Baars, Peter S.

    2004-01-01

    A multi-layered permeable reactive barrier (PRB) has been installed in Mortandad Canyon, on the Pajarito Plateau in the north-central part of LANL, to demonstrate in-situ treatment of a suite of contaminants with dissimilar geochemical properties. The PRB will also mitigate possible vulnerabilities from downgradient contaminant movement within alluvial and deeper perched groundwater. Mortandad Canyon was selected as the location for this demonstration project because the flow of alluvial groundwater is constrained by the geology of the canyon, a large network of monitoring wells already were installed along the canyon reach, and the hydrochemistry and contaminant history of the canyon is well-documented. The PRB uses a funnel-and-gate system with a series of four reactive media cells to immobilize or destroy contaminants present in alluvial groundwater, including strontium-90, plutonium-238,239,240, americium-241, perchlorate, and nitrate. The four cells, ordered by sequence of contact with the groundwater, consist of gravel-sized scoria (for colloid removal); phosphate rock containing apatite (for metals and radionuclides); pecan shells and cotton seed admixed with gravel (bio-barrier, to deplete dissolved oxygen and destroy potential RCRA organic compounds, nitrate and perchlorate); and limestone (pH buffering and anion adsorption). Design elements of the PRB are based on laboratory-scale treatability studies and on a field investigation of hydrologic, geochemical, and geotechnical parameters. The PRB was designed with the following criteria: 1-day residence time within the biobarrier, 10-year lifetime, minimization of surface water infiltration and erosion, optimization of hydraulic capture, and minimization of excavated material requiring disposal. Each layer has been equipped with monitoring wells or ports to allow sampling of groundwater and reactive media, and monitor wells are located immediately adjacent to the up- and down-gradient perimeter of the

  17. 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.

  18. 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.

  19. Monitoring trichloroethene remediation at an iron permeable reactive barrier using stable carbon isotopic analysis

    Science.gov (United States)

    VanStone, Nancy; Przepiora, Andrzej; Vogan, John; Lacrampe-Couloume, Georges; Powers, Brian; Perez, Ernesto; Mabury, Scott; Sherwood Lollar, Barbara

    2005-08-01

    Stable carbon isotopic analysis, in combination with compositional analysis, was used to evaluate the performance of an iron permeable reactive barrier (PRB) for the remediation of ground water contaminated with trichloroethene (TCE) at Spill Site 7 (SS7), F.E. Warren Air Force Base, Wyoming. Compositional data indicated that although the PRB appeared to be reducing TCE to concentrations below treatment goals within and immediately downgradient of the PRB, concentrations remained higher than expected at wells further downgradient (i.e. > 9 m) of the PRB. At two wells downgradient of the PRB, TCE concentrations were comparable to upgradient values, and δ13C values of TCE at these wells were not significantly different than upgradient values. Since the process of sorption/desorption does not significantly fractionate carbon isotope values, this suggests that the TCE observed at these wells is desorbing from local aquifer materials and was present before the PRB was installed. In contrast, three other downgradient wells show significantly more enriched δ13C values compared to the upgradient mean. In addition, δ13C values for the degradation products of TCE, cis-dichloroethene and vinyl chloride, show fractionation patterns expected for the products of the reductive dechlorination of TCE. Since concentrations of both TCE and degradation products drop to below detection limit in wells within the PRB and directly below it, these downgradient chlorinated hydrocarbon concentrations are attributed to desorption from local aquifer material. The carbon isotope values indicate that this dissolved contaminant is subject to local degradation, likely due to in situ microbial activity.

  20. Monitoring trichloroethene remediation at an iron permeable reactive barrier using stable carbon isotopic analysis.

    Science.gov (United States)

    VanStone, Nancy; Przepiora, Andrzej; Vogan, John; Lacrampe-Couloume, Georges; Powers, Brian; Perez, Ernesto; Mabury, Scott; Sherwood Lollar, Barbara

    2005-08-01

    Stable carbon isotopic analysis, in combination with compositional analysis, was used to evaluate the performance of an iron permeable reactive barrier (PRB) for the remediation of ground water contaminated with trichloroethene (TCE) at Spill Site 7 (SS7), F.E. Warren Air Force Base, Wyoming. Compositional data indicated that although the PRB appeared to be reducing TCE to concentrations below treatment goals within and immediately downgradient of the PRB, concentrations remained higher than expected at wells further downgradient (i.e. >9 m) of the PRB. At two wells downgradient of the PRB, TCE concentrations were comparable to upgradient values, and delta13C values of TCE at these wells were not significantly different than upgradient values. Since the process of sorption/desorption does not significantly fractionate carbon isotope values, this suggests that the TCE observed at these wells is desorbing from local aquifer materials and was present before the PRB was installed. In contrast, three other downgradient wells show significantly more enriched delta13C values compared to the upgradient mean. In addition, delta13C values for the degradation products of TCE, cis-dichloroethene and vinyl chloride, show fractionation patterns expected for the products of the reductive dechlorination of TCE. Since concentrations of both TCE and degradation products drop to below detection limit in wells within the PRB and directly below it, these downgradient chlorinated hydrocarbon concentrations are attributed to desorption from local aquifer material. The carbon isotope values indicate that this dissolved contaminant is subject to local degradation, likely due to in situ microbial activity.

  1. Evaluation of [14C] and [13C]Sucrose as Blood-Brain Barrier Permeability Markers.

    Science.gov (United States)

    Miah, Mohammad K; Chowdhury, Ekram A; Bickel, Ulrich; Mehvar, Reza

    2017-06-01

    Nonspecific quantitation of [ 14 C]sucrose in blood and brain has been routinely used as a quantitative measure of the in vivo blood-brain barrier (BBB) integrity. However, the reported apparent brain uptake clearance (K in ) of the marker varies widely (∼100-fold). We investigated the accuracy of the use of the marker in comparison with a stable isotope of sucrose ([ 13 C]sucrose) measured by a specific liquid chromatography-tandem mass spectrometry method. Rats received single doses of each marker, and the K in values were determined. Surprisingly, the K in value of [ 13 C]sucrose was 6- to 7-fold lower than that of [ 14 C]sucrose. Chromatographic fractionation after in vivo administration of [ 14 C]sucrose indicated that the majority of the brain content of radioactivity belonged to compounds other than the intact [ 14 C]sucrose. However, mechanistic studies failed to reveal any substantial metabolism of the marker. The octanol:water partition coefficient of [ 14 C]sucrose was >2-fold higher than that of [ 13 C]sucrose, indicating the presence of lipid-soluble impurities in the [ 14 C]sucrose solution. Our data indicate that [ 14 C]sucrose overestimates the true BBB permeability to sucrose. We suggest that specific quantitation of the stable isotope ( 13 C) of sucrose is a more accurate alternative to the current widespread use of the radioactive sucrose as a BBB marker. Copyright © 2017 American Pharmacists Association®. Published by Elsevier Inc. All rights reserved.

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

    Science.gov (United States)

    Floris, S; Blezer, E L A; Schreibelt, G; Döpp, E; van der Pol, S M A; Schadee-Eestermans, I L; Nicolay, K; Dijkstra, C D; de Vries, H E

    2004-03-01

    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 leakage is an early event and precedes massive cellular infiltration in the development of acute experimental allergic encephalomyelitis (EAE), the animal correlate of multiple sclerosis. Cerebrovascular leakage and monocytes infiltrates were separately monitored by quantitative in vivo MRI during the course of the disease. Magnetic resonance enhancement of the contrast agent gadolinium diethylenetriaminepentaacetate (Gd-DTPA), reflecting vascular leakage, occurred concomitantly with the onset of neurological signs and was already at a maximal level at this stage of the disease. Immunohistochemical analysis also confirmed the presence of the serum-derived proteins such as fibrinogen around the brain vessels early in the disease, whereas no cellular infiltrates could be detected. MRI further demonstrated that Gd-DTPA leakage clearly preceded monocyte infiltration as imaged by the contrast agent based on ultra small particles of iron oxide (USPIO), which was maximal only during full-blown EAE. Ultrastructural and immunohistochemical investigation revealed that USPIOs were present in newly infiltrated macrophages within the inflammatory lesions. To validate the use of USPIOs as a non-invasive tool to evaluate therapeutic strategies, EAE animals were treated with the immunomodulator 3-hydroxy-3-methylglutaryl Coenzyme A reductase inhibitor, lovastatin, which ameliorated clinical scores. MRI showed that the USPIO load in the brain was significantly diminished in lovastatin-treated animals. Data indicate that cerebrovascular leakage and monocytic trafficking into the brain are two distinct processes in the development of inflammatory lesions during multiple sclerosis, which can

  3. Impact of drug permeability of blood-brain barrier after whole brain conventional fractionation irradiation

    International Nuclear Information System (INIS)

    Zhang Longzhen; Cao Yuandong; Chen Yong; Yu Changzhou; Zhuang Ming

    2006-01-01

    Objective: To explore the effect of drug permeability in rat blood-brain barrier(BBB) after different doses of whole brain conventional fractionation irradiation in rats and provide the experimental basis for the optimum time of clinical chemotherapy. Methods: According to different irradiation doses, 100 adult Sprague-Dowley rats were divided randomly into 5 groups: the normal control group(0 Gy); 10 Gy; 20 Gy; 30 Gy; and 40 Gy group. All rats were exposed to conventional fractionation(2 Gy/d, 5 d/w) with 60 Co γ-ray. MTX(25 mg/kg) was injected through the tail mainline 16 hours after whole brain irradiation. Cerebrospinal fluid(CSF) and blood were collected 2 hours later. Those samples were used to assay MTX concentration using RP-HPLC. Results: MTX mean concentrations in CSF was 0.07, 0.08, 0.12, 0.24, 0.23 mg/L in the control, 10 Gy, 20 Gy, 30 Gy, 40 Gy groups, respectively. All the data was analyzed with rank test of transform. MTX concentration of CSF was significantly different except the control and 10 Gy, 30 Gy and 40 Gy group. MTX concentration of blood was not significantly different in all groups (P>0.05). Conclusions: Irradiation can directly damage the function of BBB. BBB would be opened gradually following the increase of irradiation dose. It could be considered as the optimum time of chemotherapy when the whole brain irradiation ranges from 20 Gy to 30 Gy. (authors)

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

    Science.gov (United States)

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

    2018-02-01

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

  5. 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...

  6. Selection of design parameters of diffusion barrier in a passive 222Rn sampler based on activated charcoal adsorption

    International Nuclear Information System (INIS)

    Wei Suxia

    1992-01-01

    A method concerning selection of design parameters of diffusion barrier in a passive 222 Rn sampler based on activated charcoal adsorption. The proper parameter value of diffusion barrier is obtained by means of linearization of 222 Rn adsorption versus the exposure time. Thus, the influence of temperature on measured results may be greatly decreased, and higher sensitivity of the detector may be maintained

  7. 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

  8. 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.

  9. 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.

  10. 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.

  11. Effect of cryoprotectants for maintaining drug permeability barriers in porcine buccal mucosa

    DEFF Research Database (Denmark)

    Marxen, Eva; Axelsen, Mary Carlos; Pedersen, Anne Marie Lynge

    2016-01-01

    fresh or frozen/thawed tissue was determined using modified Ussing chambers. Haematoxylin-eosin stained tissue sections for histology were prepared. The permeability of nicotine across tissue frozen without cryoprotectants was significantly higher compared to tissue frozen with cryoprotectants or fresh...

  12. 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.

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

    Directory of Open Access Journals (Sweden)

    Ping GUO

    2012-02-01

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

  14. 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

  15. 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.

  16. Design Guidance for Application of Permeable Barriers to Remediate Dissolved Chlorinated Solvents,

    Science.gov (United States)

    1997-02-01

    fill slurry composed of a reactive medium, such as iron powder and guar gum , can then be injected into the fracture to form a reactive treatment zone...slurry (Owaidat, 1996). The slurry, which is composed of powdered guar bean, acts to maintain the integrity of the trench walls during installation of...the cell. The guar gum will later biodegrade to mostly water after wall completion, and will have minimal effect on the permeability of the trench

  17. Tumor necrosis factor alpha increases epithelial barrier permeability by disrupting tight junctions in Caco-2 cells

    Directory of Open Access Journals (Sweden)

    W. Cui

    2010-04-01

    Full Text Available The objectives of this study were to determine the effect of tumor necrosis factor alpha (TNF-α on intestinal epithelial cell permeability and the expression of tight junction proteins. Caco-2 cells were plated onto Transwell® microporous filters and treated with TNF-α (10 or 100 ng/mL for 0, 4, 8, 16, or 24 h. The transepithelial electrical resistance and the mucosal-to-serosal flux rates of the established paracellular marker Lucifer yellow were measured in filter-grown monolayers of Caco-2 intestinal cells. The localization and expression of the tight junction protein occludin were detected by immunofluorescence and Western blot analysis, respectively. SYBR-Green-based real-time PCR was used to measure the expression of occludin mRNA. TNF-α treatment produced concentration- and time-dependent decreases in Caco-2 transepithelial resistance and increases in transepithelial permeability to the paracellular marker Lucifer yellow. Western blot results indicated that TNF-α decreased the expression of phosphorylated occludin in detergent-insoluble fractions but did not affect the expression of non-phosphorylated occludin protein. Real-time RT-PCR data showed that TNF-α did not affect the expression of occludin mRNA. Taken together, our data demonstrate that TNF-α increases Caco-2 monolayer permeability, decreases occludin protein expression and disturbs intercellular junctions.

  18. Measurement of blood-brain barrier permeability with positron emission tomography in patients with multiple sclerosis

    International Nuclear Information System (INIS)

    Fieschi, C.; Pozzilli, C.; Bernardi, S.; Bozzao, L.; Lenzi, G.L.; Picozzi, P.; Iannotti, F.; Conforti, P.

    1988-01-01

    The purpose of the investigation was to elucidate the role of positron emission tomography using 68 Ga-EDTA in the study of blood-brain barrier abnormalities associated with multiple sclerosis. 14 refs.; 1 figure

  19. 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; ...

  20. Passive House and Low Energy Buildings: Barriers and Opportunities for Future Development within UK Practice

    Directory of Open Access Journals (Sweden)

    Adrian Pitts

    2017-02-01

    Full Text Available This paper describes research carried out to understand better the current and future emphases emerging from practice for the design and development of “Passive House” and low energy buildings. The paper initially discusses the extant position, particularly with regards to the UK and considers how regulation and assessment systems have changed in recent years, as well as projecting ideas forward taking account of contemporary political situations. Relevant previous research into Passive House and low energy design and construction is then reviewed. The need for greater understanding of professionals and their communication/collaboration with clients were identified as important factors impacting development. Those involved in the design and construction practice therefore have key roles in the process of enhancing energy efficiency. Five industry/practice based professional organizations were interviewed in-depth to gain insights into their experience of current low energy design, and to extrapolate the outcomes to future scenarios. The method employed used a structured interview technique with key question areas to lead the discussion. The anonymized responses discussed are grouped around key themes. Evidence suggests there has been a move towards the adoption of voluntary high level standards because of potential limitations with mandatory regulations and because of perceived additional benefits of higher quality design. This change is now more than previously, being driven by informed clients, design professionals, and the industry, with regulation taking a secondary role. New opportunities and barriers are becoming evident and these require further consideration.

  1. Potential and barrier study. Passive house and near-zero energy buildings; Potensial- og barrierestudie. Passivhus og naer nullenergibygninger

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2012-07-01

    The main conclusion from the analysis is that the barriers to realize both passive and near zero-energy buildings are significant. In addition to being a mere economic assessment indicates that 30-70% of the technical potential is not profitable depending on energy price levels, the barriers is reducing the economic potential with approximately another half as a realistic market potential.(eb)

  2. 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.

  3. Influence of capillary barrier effect on biogas distribution at the base of passive methane oxidation biosystems: Parametric study.

    Science.gov (United States)

    Ahoughalandari, Bahar; Cabral, Alexandre R

    2017-05-01

    The efficiency of methane oxidation in passive methane oxidation biosystems (PMOBs) is influenced by, among other things, the intensity and distribution of the CH 4 loading at the base of the methane oxidation layer (MOL). Both the intensity and distribution are affected by the capillary barrier that results from the superposition of the two materials constituting the PMOB, namely the MOL and the gas distribution layer (GDL). The effect of capillary barriers on the unsaturated flow of water has been well documented in the literature. However, its effect on gas flow through PMOBs is still poorly documented. In this study, sets of numerical simulations were performed to evaluate the effect of unsaturated hydraulic characteristics of the MOL material on the value and distribution of moisture and hence, the ease and uniformity in the distribution of the upward flow of biogas along the GDL-MOL interface. The unsaturated hydraulic parameters of the materials used to construct the experimental field plot at the St-Nicephore landfill (Quebec, Canada) were adopted to build the reference simulation of the parametric study. The behavior of the upward flow of biogas for this particular material was analyzed based on its gas intrinsic permeability function, which was obtained in the laboratory. The parameters that most influenced the distribution and the ease of biogas flow at the base of the MOL were the saturated hydraulic conductivity and pore size distribution of the MOL material, whose effects were intensified as the slope of the interface increased. The effect of initial dry density was also assessed herein. Selection of the MOL material must be made bearing in mind that these three parameters are key in the effort to prevent unwanted restriction in the upward flow of biogas, which may result in the redirection of biogas towards the top of the slope, leading to high CH 4 fluxes (hotspots). In a well-designed PMOB, upward flow of biogas across the GDL-MOL interface is

  4. 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)

  5. 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...

  6. 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.

  7. 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.

  8. Topical antihistamines display potent anti-inflammatory activity linked in part to enhanced permeability barrier function

    DEFF Research Database (Denmark)

    Lin, Tzu-Kai; Man, Mao-Qiang; Santiago, Juan-Luis

    2013-01-01

    antagonists likely oppose mast cell-derived histamines. In four immunologically diverse, murine disease models, characterized by either inflammation alone (acute irritant contact dermatitis, acute allergic contact dermatitis) or by prominent barrier abnormalities (subacute allergic contact dermatitis, atopic...... of epidermal differentiation, leading to thickened cornified envelopes; and (ii) enhanced epidermal lipid synthesis and secretion. As barrier homeostasis was enhanced to a comparable extent in mast cell-deficient mice, with no further improvement following application of topical H1/2r antagonists, H1/2r...... dermatitis), topical H1/2r agonists aggravated, whereas H1/2r antagonists improved, inflammation and/or barrier function. The apparent ability of topical H1r/2r antagonists to target epidermal H1/2r could translate into increased efficacy in the treatment of inflammatory dermatoses, likely due to decreased...

  9. Creation of a subsurface permeable treatment barrier using in situ redox manipulation

    International Nuclear Information System (INIS)

    Fruchter, J.S.; Cole, C.R.; Williams, M.D.

    1997-01-01

    The goal of in situ redox manipulation is to create a permeable treatment zone in the subsurface for remediating redox-sensitive contaminants in groundwater. The permeable treatment zone is created just downstream of the contaminant plume or contaminant source through the injection of reagents and/or microbial nutrients to alter the redox potential of the aquifer fluids and sediments. Contaminant plumes migrating through this manipulated zone can then be destroyed or immobilized. In a field test at the Hanford Site, ∼77,000 L of buffered sodium dithionite solution were successfully injected into the unconfined aquifer at the 100-H Area in September 1995. The target contaminant was chromate. No significant plugging of the well screen or the formation was detected during any phase of the test. Dithionite was detected in monitoring wells at least 7.5 m from the injection point. Data were obtained from all three phases of the test (i.e., injection, reaction, withdrawal). Preliminary core data show that from 60% to 100% of the available reactive iron in the targeted aquifer sediments was reduced by the injected dithionite. One year after the injection, groundwater in the treatment zone remains anoxic. Total and hexavalent chromium levels in groundwater have been reduced from a preexperiment concentration of ∼60 μg/L to below the detection limit of the analytical methods

  10. Diel coral reef acidification driven by porewater advection in permeable sands, Heron Island, Great Barrier Reef

    DEFF Research Database (Denmark)

    Santos, Isaac R.; Glud, Ronnie N.; Maher, Damien

    2011-01-01

    Little is known about how biogeochemical processes in permeable sediments affect the pH of coastal waters. We demonstrate that seawater recirculation in permeable sands can play a major role in proton (H+) cycling in a coral reef lagoon. The diel pH range (up to 0.75 units) in the Heron Island...... lagoon was the broadest ever reported for reef waters, and the night‐time pH (7.69) was comparable to worst‐case scenario predictions for seawater pH in 2100. The net contribution of coarse carbonate sands to the whole system H+ fluxes was only 9% during the day, but approached 100% at night when small...... scale (i.e., flow and topography‐induced pressure gradients) and large scale (i.e., tidal pumping as traced by radon) seawater recirculation processes were synergistic. Reef lagoon sands were a net sink for H+, and the sink strength was a function of porewater flushing rate. Our observations suggest...

  11. 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.

  12. Lack of IL-6 increases blood–brain barrier permeability in fungal

    Indian Academy of Sciences (India)

    Interleukin (IL-6) is a multifunctional cytokine, and numerous studies have shown that IL‐6 influences the integrity of the blood–brain barrier. In this study we investigated the role of IL-6 in Cryptococcus meningitis. First, wild-type or IL-6−/− mice were injected with Cryptococcus neoformans (C. neoformans) and the survival ...

  13. Blood-Brain Barrier Permeability of Normal Appearing White Matter in Relapsing-Remitting Multiple Sclerosis

    DEFF Research Database (Denmark)

    Lund, Henrik; Krakauer, Martin; Skimminge, Arnold

    2013-01-01

    Background: Multiple sclerosis (MS) affects the integrity of the blood-brain barrier (BBB). Contrast-enhanced T1 weighted magnetic resonance imaging (MRI) is widely used to characterize location and extent of BBB disruptions in focal MS lesions. We employed quantitative T1 measurements before...

  14. Highly organic natural media as permeable reactive barriers: TCE partitioning and anaerobic degradation profile in eucalyptus mulch and compost.

    Science.gov (United States)

    Öztürk, Zuhal; Tansel, Berrin; Katsenovich, Yelena; Sukop, Michael; Laha, Shonali

    2012-10-01

    Batch and column experiments were conducted with eucalyptus mulch and commercial compost to evaluate suitability of highly organic natural media to support anaerobic decomposition of trichloroethylene (TCE) in groundwater. Experimental data for TCE and its dechlorination byproducts were analyzed with Hydrus-1D model to estimate the partitioning and kinetic parameters for the sequential dechlorination reactions during TCE decomposition. The highly organic natural media allowed development of a bioactive zone capable of decomposing TCE under anaerobic conditions. The first order TCE biodecomposition reaction rates were 0.23 and 1.2d(-1) in eucalyptus mulch and compost media, respectively. The retardation factors in the eucalyptus mulch and compost columns for TCE were 35 and 301, respectively. The results showed that natural organic soil amendments can effectively support the anaerobic bioactive zone for remediation of TCE contaminated groundwater. The natural organic media are effective environmentally sustainable materials for use in permeable reactive barriers. Copyright © 2012 Elsevier Ltd. All rights reserved.

  15. Organic substrates as electron donors in permeable reactive barriers for removal of heavy metals from acid mine drainage.

    Science.gov (United States)

    Kijjanapanich, P; Pakdeerattanamint, K; Lens, P N L; Annachhatre, A P

    2012-12-01

    This research was conducted to select suitable natural organic substrates as potential carbon sources for use as electron donors for biological sulphate reduction in a permeable reactive barrier (PRB). A number of organic substrates were assessed through batch and continuous column experiments under anaerobic conditions with acid mine drainage (AMD) obtained from an abandoned lignite coal mine. To keep the heavy metal concentration at a constant level, the AMD was supplemented with heavy metals whenever necessary. Under anaerobic conditions, sulphate-reducing bacteria (SRB) converted sulphate into sulphide using the organic substrates as electron donors. The sulphide that was generated precipitated heavy metals as metal sulphides. Organic substrates, which yielded the highest sulphate reduction in batch tests, were selected for continuous column experiments which lasted over 200 days. A mixture of pig-farm wastewater treatment sludge, rice husk and coconut husk chips yielded the best heavy metal (Fe, Cu, Zn and Mn) removal efficiencies of over 90%.

  16. [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

  17. The effect of high energy electron irradiation on blood-brain barrier permeability to haloperidol and stobadin in rats

    Energy Technology Data Exchange (ETDEWEB)

    Trnovec, T; Kallay, Z [Komenskeho Univ., Bratislava (Czechoslovakia). Inst. of Preventive and Clinical Medicine; Volenec, K [Karlova Univ., Hradec Kralove (Czechoslovakia). Lekarska Fakulta; Bezek, S; Durisova, M; Scasnar, V; Kubu, M [Slovenska Akademia Vied, Bratislava (Czechoslovakia). Ustav Experimentalnej Farmakologie; Svoboda, V [Medical Academy J.E. Purkyne, Hradec Kralove (Czechoslovakia)

    1991-10-01

    The heads of rats were irradiated by 4 MeV electrons in doses 90, 180, and 360 Gy. The observed times of deaths ranged 120-600, 60-420, and 150-370 min after 90, 180, and 360 Gy, respectively. A dose dependent decrease of the brain uptake index of haloperidol was observed 1 and 3 h post radiation. On the other hand an increased brain uptake index was found for stobadin after head irradiation with doses of 180 and 360 Gy. Regional cerebral blood flow, blood pressure, and heart rate were not significantly altered in the period following irradiation with 180 Gy. The observed changes in blood-brain barrier (BBB) permeability seem to be the result of the damaged function of morphological structures forming the BBB rather than altered regional blood flow. (orig.).

  18. Modeling localized delivery of Doxorubicin to the brain following focused ultrasound enhanced blood-brain barrier permeability

    International Nuclear Information System (INIS)

    Nhan, Tam; Burgess, Alison; Hynynen, Kullervo; Lilge, Lothar

    2014-01-01

    Doxorubicin (Dox) is a well-established chemotherapeutic agent, however it has limited efficacy in treating brain malignancies due to the presence of the blood-brain barrier (BBB). Recent preclinical studies have demonstrated that focused ultrasound induced BBB disruption (BBBD) enables efficient delivery of Dox to the brain. For future treatment planning of BBBD-based drug delivery, it is crucial to establish a mathematical framework to predict the effect of transient BBB permeability enhancement on the spatiotemporal distribution of Dox at the targeted area. The constructed model considers Dox concentrations within three compartments (plasma, extracellular, intracellular) that are governed by various transport processes (e.g. diffusion in interstitial space, exchange across vessel wall, clearance by cerebral spinal fluid, uptake by brain cells). By examining several clinical treatment aspects (e.g. sonication scheme, permeability enhancement, injection mode), our simulation results support the experimental findings of optimal interval delay between two consecutive sonications and therapeutically-sufficient intracellular concentration with respect to transfer constant K trans range of 0.01–0.03 min −1 . Finally, the model suggests that infusion over a short duration (20–60 min) should be employed along with single-sonication or multiple-sonication at 10 min interval to ensure maximum delivery to the intracellular compartment while attaining minimal cardiotoxicity via suppressing peak plasma concentration. (paper)

  19. 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.

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

    Directory of Open Access Journals (Sweden)

    Oláh G

    2013-09-01

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

  1. 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.

  2. Degassing, gas retention and release in Fe(0) permeable reactive barriers.

    Science.gov (United States)

    Ruhl, Aki S; Jekel, Martin

    2014-04-01

    Corrosion of Fe(0) has been successfully utilized for the reductive treatment of multiple contaminants. Under anaerobic conditions, concurrent corrosion leads to the generation of hydrogen and its liberation as a gas. Gas bubbles are mobile or trapped within the irregular pore structure leading to a reduction of the water filled pore volume and thus decreased residence time and permeability (gas clogging). With regard to the contaminant transport to the reactive site, the estimation of surface properties of the reactive material indicated that individual gas bubbles only occupied minor contact areas of the reactive surface. Quantification of gas entrapment by both gravimetrical and tracer investigations revealed that development of preferential flow paths was not significant. A novel continuous gravimetrical method was implemented to record variations in gas entrapment and gas bubble releases from the reactive filling. Variation of grain size fractions revealed that the pore geometry had a significant impact on gas release. Large pores led to the release of comparably large gas amounts while smaller volumes were released from finer pores with a higher frequency. Relevant processes are explained with a simplified pictorial sequence that incorporates relevant mechanisms. Copyright © 2014 Elsevier B.V. All rights reserved.

  3. Controlled ultrasound-induced blood-brain barrier disruption using passive acoustic emissions monitoring.

    Directory of Open Access Journals (Sweden)

    Costas D Arvanitis

    Full Text Available The ability of ultrasonically-induced oscillations of circulating microbubbles to permeabilize vascular barriers such as the blood-brain barrier (BBB holds great promise for noninvasive targeted drug delivery. A major issue has been a lack of control over the procedure to ensure both safe and effective treatment. Here, we evaluated the use of passively-recorded acoustic emissions as a means to achieve this control. An acoustic emissions monitoring system was constructed and integrated into a clinical transcranial MRI-guided focused ultrasound system. Recordings were analyzed using a spectroscopic method that isolates the acoustic emissions caused by the microbubbles during sonication. This analysis characterized and quantified harmonic oscillations that occur when the BBB is disrupted, and broadband emissions that occur when tissue damage occurs. After validating the system's performance in pilot studies that explored a wide range of exposure levels, the measurements were used to control the ultrasound exposure level during transcranial sonications at 104 volumes over 22 weekly sessions in four macaques. We found that increasing the exposure level until a large harmonic emissions signal was observed was an effective means to ensure BBB disruption without broadband emissions. We had a success rate of 96% in inducing BBB disruption as measured by in contrast-enhanced MRI, and we detected broadband emissions in less than 0.2% of the applied bursts. The magnitude of the harmonic emissions signals was significantly (P<0.001 larger for sonications where BBB disruption was detected, and it correlated with BBB permeabilization as indicated by the magnitude of the MRI signal enhancement after MRI contrast administration (R(2 = 0.78. Overall, the results indicate that harmonic emissions can be a used to control focused ultrasound-induced BBB disruption. These results are promising for clinical translation of this technology.

  4. 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

  5. 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

  6. 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 ...

  7. 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...

  8. 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

  9. Application of kinetic models to the design of a calcite permeable reactive barrier (PRB) for fluoride remediation.

    Science.gov (United States)

    Cai, Qianqian; Turner, Brett D; Sheng, Daichao; Sloan, Scott

    2018-03-01

    The kinetics of fluoride sorption by calcite in the presence of metal ions (Co, Mn, Cd and Ba) have been investigated and modelled using the intra-particle diffusion (IPD), pseudo-second order (PSO), and the Hill 4 and Hill 5 kinetic models. Model comparison using the Akaike Information Criterion (AIC), the Schwarz Bayseian Information Criterion (BIC) and the Bayes Factor allows direct comparison of model results irrespective of the number of model parameters. Information Criterion results indicate "very strong" evidence that the Hill 5 model was the best fitting model for all observed data due to its ability to fit sigmoidal data, with confidence contour analysis showing the model parameters were well constrained by the data. Kinetic results were used to determine the thickness of a calcite permeable reactive barrier required to achieve up to 99.9% fluoride removal at a groundwater flow of 0.1 m.day -1 . Fluoride removal half-life (t 0.5 ) values were found to increase in the order Ba ≈ stonedust (a 99% pure natural calcite) barrier width of 0.97 ± 0.02 m was found to be required for the fluoride/calcite (stonedust) only system when using no factor of safety, whilst in the presence of Mn and Co, the width increased to 2.76 ± 0.28 and 19.83 ± 0.37 m respectively. In comparison, the PSO model predicted a required barrier thickness of ∼46.0, 62.6 & 50.3 m respectively for the fluoride/calcite, Mn and Co systems under the same conditions. Crown Copyright © 2017. Published by Elsevier Ltd. All rights reserved.

  10. Permeable reactive barriers for the remediation of groundwater in a mining area: results for a pilot-scale project

    Science.gov (United States)

    Martinez-Sanchez, Maria Jose; Perez-Sirvent, Carmen; Garcia-Lorenzo, Maria Luz; Martinez-Lopez, Salvadora; Perez-Espinosa, Victor; Gonzalez-Ciudad, Eva; Belen Martinez-Martinez, Lucia; Hernandez, Carmen; Molina-Ruiz, Jose

    2017-04-01

    The Sierra Minera of Cartagena-La Union is located in the Region of Murcia, Southeast of Spain. This zone presents high levels of heavy metals due to natural, geogenic reasons. In addition, the prolonged mining activity, and subsequent abandonment of farms, has had consequences on the environment, including severe affectation of the groundwater in the area. To remediate this situation, the Permeable Reactive Barrier (PRB) technology was assayed, which required in addition to the hydro-geological study of the zone, a careful optimization study for the design and construction of PRBs. For such a purpose a pilot-scale project was developed, and this communication reports some of the most relevant findings obtained after a four-years monitorization period. The selected reactive material for the PRBs was limestone filler. The filler is a waste material produced in many factories in the zone. These residues have good adsorption properties, high alkalinity, low cost and high availability, which make them suitable for use in remediation. The PRB was constituted by a 50% limestone filler and 50% sand, a proportion optimized by means of independent batch experiments. A layer of gravel was placed at the top, and on it a layer of natural soil. The barrier was designed in the form of a continuous trench, because the level of the contaminated groundwater was not very deep. In this way, the barrier could be prepared with standard excavation equipment. Parallel to the barrier, 6 wells where arranged downstream for sample collection. The pH and conductivity of the samples was measured directly in situ, and the content of Zn, Cd, Cu, Fe, and Pb were analyzed in the laboratory. All the samples collected after the PRB was constructed had basic pH values between 7.5 and 8. The conductivity was between 5 and 11 mS / cm except for the well 4, which had a value of 3.70 mS / cm. The concentration values of trace elements were below the detection limit (atomic absorption measurement) in

  11. Permeability of the blood-brain barrier to the neurotensin8-13 analog NT1.

    Science.gov (United States)

    Banks, W A; Wustrow, D J; Cody, W L; Davis, M D; Kastin, A J

    1995-10-09

    Neurotensin (NT) has been suggested to be a neuropeptide with therapeutic potential. We used multiple-time regression analysis to measure the unidirectional influx constant (Ki) of a tritiated analog of NT8-13, NT1, with improved metabolic stability. The Ki of [3H]NT1 across the blood-brain barrier (BBB) was 5.12(10(-4)) ml/g-min and was decreased 66% by unlabeled NT1 system. The amount of NT1 crossing the BBB, 0.087% of the injected dose per gram of brain, is consistent with its exerting central effects after peripheral administration. The stable [3H]NT1 crossed the BBB in intact form as assessed by HPLC and completely crossed the endothelial cells that comprise the BBB as assessed by the capillary depletion method. The presence of a transport system could be important for the development of NT analogs.

  12. 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...

  13. 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。

  14. Effect of chemical permeation enhancers on stratum corneum barrier lipid organizational structure and interferon alpha permeability.

    Science.gov (United States)

    Moghadam, Shadi H; Saliaj, Evi; Wettig, Shawn D; Dong, Chilbert; Ivanova, Marina V; Huzil, J Torin; Foldvari, Marianna

    2013-06-03

    The outermost layer of the skin, known as the stratum corneum (SC), is composed of dead corneocytes embedded in an intercellular lipid matrix consisting of ceramides, free fatty acids, and cholesterol. The high level of organization within this matrix protects the body by limiting the permeation of most compounds through the skin. While essential for its protective functions, the SC poses a significant barrier for the delivery of topically applied pharmaceutical agents. Chemical permeation enhancers (CPEs) can increase delivery of small drug compounds into the skin by interacting with the intercellular lipids through physical processes including extraction, fluidization, increased disorder, and phase separation. However, it is not clear whether these same mechanisms are involved in delivery of biotherapeutic macromolecules, such as proteins. Here we describe the effect of three categories of CPEs {solvents [ethanol, propylene glycol, diethylene glycol monoethyl ether (transcutol), oleic acid], terpenes [menthol, nerol, camphor, methyl salicylate], and surfactants [Tween 80, SDS, benzalkonium chloride, polyoxyl 40 hydrogenated castor oil (Cremophor RH40), didecyldimethylammonium bromide (DDAB), didecyltrimethylammonium bromide (DTAB)]} on the lipid organizational structure of human SC as determined by X-ray scattering studies. Small- and wide-angle X-ray scattering studies were conducted to correlate the degree of structural changes and hydrocarbon chain packing in SC lipids caused by these various classes of CPEs to the extent of permeation of interferon alpha-2b (IFNα), a 19 kDa protein drug, into human skin. With the exception of solvents, propylene glycol and ethanol, all classes of CPEs caused increased disordering of lamellar and lateral packing of lipids. We observed that the highest degree of SC lipid disordering was caused by surfactants (especially SDS, DDAB, and DTAB) followed by terpenes, such as nerol. Interestingly, in vitro skin permeation studies

  15. Development of modified flyash as a permeable reactive barrier medium for a former manufactured gas plant site, Northern Ireland

    Science.gov (United States)

    Doherty, R.; Phillips, D. H.; McGeough, K. L.; Walsh, K. P.; Kalin, R. M.

    2006-05-01

    A sequential biological permeable reactive barrier (PRB) was determined to be the best option for remediating groundwater that has become contaminated with a wide range of organic contaminants (i.e., benzene, toluene, ethylbenzene, xylene and polyaromatic hydrocarbons), heavy metals (i.e., lead and arsenic), and cyanide at a former manufactured gas plant after 150 years of operation in Portadown, Northern Ireland. The objective of this study was to develop a modified flyash that could be used in the initial cell within a sequential biological PRB to filter complex contaminated groundwater containing ammonium. Flyash modified with lime (CaOH) and alum was subjected to a series of batch tests which investigated the modified cation exchange capacity (CEC) and rate of removal of anions and cations from the solution. These tests showed that a high flyash composition medium (80%) could remove 8.65 mol of ammonium contaminant for every kilogram of medium. The modified CEC procedure ruled out the possibility of cation exchange as the major removal mechanism. The medium could also adsorb anions as well as cations (i.e., Pb and Cr), but not with the same capacity. The initial mechanism for Pb and Cr removal is probably precipitation. This is followed by sorption, which is possibly the only mechanism for the removal of dichromate anions. Scanning electron microscopic analysis revealed very small (productive zeolite formation. Surface area measurements showed that biofilm growth on the medium could be a major factor in the comparative reduction of surface area between real and synthetic contaminant groundwaters. The modified flyash was found to be a highly sorptive granular material that did not inhibit microbiological activity, however, leaching tests revealed that the medium would fail as a long-term barrier material.

  16. Acid rock drainage passive remediation using alkaline clay and impacts of vegetation and saturated sand barrier

    Science.gov (United States)

    Plaza, F.; Wen, Y.; Liang, X.

    2017-12-01

    Acid rock drainage (ARD) caused by abundance of coal refuse (CR) deposits in mining regions requires adequate treatment to prevent serious water pollution due to its acidity and high concentrations of sulfate and metals/metalloids. Over the past decades, various approaches have been explored and developed to remediate ARD. This study uses laboratory experiments to investigate the effectiveness and impacts of ARD passive remediation using alkaline clay (AC), a by-product of the aluminum refining process. Twelve column kinetic leaching experiments were set up with CR/AC mixing ratios ranging from 1%AC to 10%AC. Samples were collected from these columns to measure the pH, sulfate, metals/metalloids, acidity and alkalinity. Additional tests of XRD and acid base accounting were also conducted to better characterize the mineral phase in terms of the alkalinity and acidity potential. Based on the leachate measurement results, these columns were further classified into two groups of neutral/near neutral pH and acidic pH for further analysis. In addition, impacts of the vegetation and saturated sand layer on the remediation effectiveness were explored. The results of our long-term (more than three years in some cases) laboratory experiments show that AC is an effective ARD remediation material for the neutralization of leachate pH and immobilization of sulfate and metals such as Fe, Mn, Cu, Zn, Ni, Pb, Cd, Co. The CR/AC mixing ratios higher than 3%AC are found to be effective, with 10% close to optimal. Moreover, the results demonstrate the benefits of using vegetation and a saturated sand barrier. Vegetation acted as a phytoaccumulation/phytoextraction agent, causing an additional immobilization of metals. The saturated sand barrier blocked the oxygen and water diffusion downwards, leading to a reduction of the pyrite oxidation rate. Finally, the proposed remediation approach shows that the acidity consumption will likely occur before all the alkalinity is exhausted

  17. Examples of Department of Energy Successes for Remediation of Contaminated Groundwater: Permeable Reactive Barrier and Dynamic Underground Stripping ASTD Projects

    International Nuclear Information System (INIS)

    Purdy, C.; Gerdes, K.; Aljayoushi, J.; Kaback, D.; Ivory, T.

    2002-01-01

    Since 1998, the Department of Energy's (DOE) Office of Environmental Management has funded the Accelerated Site Technology Deployment (ASTD) Program to expedite deployment of alternative technologies that can save time and money for the environmental cleanup at DOE sites across the nation. The ASTD program has accelerated more than one hundred deployments of new technologies under 76 projects that focus on a broad spectrum of EM problems. More than 25 environmental restoration projects have been initiated to solve the following types of problems: characterization of the subsurface using chemical, radiological, geophysical, and statistical methods; treatment of groundwater contaminated with DNAPLs, metals, or radionuclides; and other projects such as landfill covers, purge water management systems, and treatment of explosives-contaminated soils. One of the major goals of the ASTD Program is to deploy a new technology or process at multiple DOE sites. ASTD projects are encouraged to identify subsequent deployments at other sites. Some of the projects that have successfully deployed technologies at multiple sites focusing on cleanup of contaminated groundwater include: Permeable Reactive Barriers (Monticello, Rocky Flats, and Kansas City), treating uranium and organics in groundwater; and Dynamic Underground Stripping (Portsmouth, and Savannah River), thermally treating DNAPL source zones. Each year more and more new technologies and approaches are being used at DOE sites due to the ASTD program. DOE sites are sharing their successes and communicating lessons learned so that the new technologies can replace the baseline or standard approaches at DOE sites, thus expediting cleanup and saving money

  18. Remediation of arsenic-contaminated groundwater using media-injected permeable reactive barriers with a modified montmorillonite: sand tank studies.

    Science.gov (United States)

    Luo, Ximing; Liu, Haifei; Huang, Guoxin; Li, Ye; Zhao, Yan; Li, Xu

    2016-01-01

    A modified montmorillonite (MMT) was prepared using an acid activation-sodium activation-iron oxide coating method to improve the adsorption capacities of natural MMTs. For MMT, its interlamellar distance increased from 12.29 to 13.36 Å, and goethite (α-FeOOH) was intercalated into its clay layers. Two novel media-injected permeable reactive barrier (MI-PRB) configurations were proposed for removing arsenic from groundwater. Sand tank experiments were conducted to investigate the performance of the two MI-PRBs: Tank A was filled with quartz sand. Tank B was packed with quartz sand and zero-valent iron (ZVI) in series, and the MMT slurry was respectively injected into them to form reactive zones. The results showed that for tank A, total arsenic (TA) removal of 98.57% was attained within the first 60 mm and subsequently descended slowly to 88.84% at the outlet. For tank B, a similar spatial variation trend was observed in the quartz sand layer, and subsequently, TA removal increased to ≥99.80% in the ZVI layer. TA removal by MMT mainly depended on both surface adsorption and electrostatic adhesion. TA removal by ZVI mainly relied on coagulation/precipitation and adsorption during the iron corrosion. The two MI-PRBs are feasible alternatives for in situ remediation of groundwater with elevated As levels.

  19. Biological permeable reactive barriers coupled with electrokinetic soil flushing for the treatment of diesel-polluted clay soil.

    Science.gov (United States)

    Mena, Esperanza; Ruiz, Clara; Villaseñor, José; Rodrigo, Manuel A; Cañizares, Pablo

    2015-01-01

    Removal of diesel from spiked kaolin has been studied in the laboratory using coupled electrokinetic soil flushing (EKSF) and bioremediation through an innovative biological permeable reactive barriers (Bio-PRBs) positioned between electrode wells. The results show that this technology is efficient in the removal of pollutants and allows the soil to maintain the appropriate conditions for microorganism growth in terms of pH, temperature, and nutrients. At the same time, EKSF was demonstrated to be a very interesting technology for transporting pollutants, microorganisms and nutrients, although results indicate that careful management is necessary to avoid the depletion of nutrients, which are effectively transported by electro-migration. After two weeks of operation, 30% of pollutants are removed and energy consumption is under 70 kWh m(-3). Main fluxes (electroosmosis and evaporation) and changes in the most relevant parameters (nutrients, diesel, microorganisms, surfactants, moisture conductivity and pH) during treatment and in a complete post-study analysis are studied to give a comprehensive description of the most relevant processes occurring in the soil (pollutant transport and biodegradation). Copyright © 2014 Elsevier B.V. All rights reserved.

  20. Environmental life cycle assessment of permeable reactive barriers: effects of construction methods, reactive materials and groundwater constituents.

    Science.gov (United States)

    Mak, Mark S H; Lo, Irene M C

    2011-12-01

    The effects of the construction methods, materials of reactive media and groundwater constituents on the environmental impacts of a permeable reactive barrier (PRB) were evaluated using life cycle assessment (LCA). The PRB is assumed to be installed at a simulated site contaminated by either Cr(VI) alone or Cr(VI) and As(V). Results show that the trench-based construction method can reduce the environmental impacts of the remediation remarkably compared to the caisson-based method due to less construction material consumption by the funnel. Compared to using the zerovalent iron (Fe(0)) and quartz sand mixture, the use of the Fe(0) and iron oxide-coated sand (IOCS) mixture can reduce the environmental impacts. In the presence of natural organic matter (NOM) in groundwater, the environmental impacts generated by the reactive media were significantly increased because of the higher usage of Fe(0). The environmental impacts are lower by using the Fe(0) and IOCS mixture in the groundwater with NOM, compared with using the Fe(0) and quartz sand mixture. Since IOCS can enhance the removal efficiency of Cr(VI) and As(V), the usage of the Fe(0) can be reduced, which in turn reduces the impacts induced by the reactive media.

  1. INFLUENCE OF GROUNDWATER GEOCHEMISTRY ON THE LONG-TERM PERFORMANCE OF IN-SITU PERMEABLE REACTIVE BARRIERS CONTAINING ZERO-VALENT IRON

    Science.gov (United States)

    Reactive barriers that couple subsurface fluid flow with a passive chemical treatment zone are emerging, cost effective approaches for in-situ remediation of contaminated groundwater. Factors such as the build-up of surface precipitates, bio-fouling, and changes in subsurface tr...

  2. 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.

  3. Long-term performance of elemental iron and hydroxyapatite for uranium retention in permeable reactive barriers used for groundwater remediation

    International Nuclear Information System (INIS)

    Biermann, V.

    2007-01-01

    Elemental iron (Fe 0 ) and hydroxyapatite (HAP) were evaluated as reactive mate-rials for use in permeable reactive barriers (PRBs) to remove uranium from conta-minated groundwater. Special attention was given to the long-term performance of the materials, which was investigated by means of column tests with a duration of up to 30 months using two different artificial groundwaters (AGW) with varying composition and uranium concentration. The interaction of the materials with AGW was studied in column tests using 237 U as a radiotracer to monitor the movement of the contamination front through the columns. The tested materials were shredded cast iron (granulated grey cast iron, 0.3 - 1.3 mm) supplied by Gotthard Mayer, Rheinfelden, Germany, and food quality grade hydroxyapatite (Ca 5 (PO 4 ) 3 OH, 99 % 0 (AGW with 9.6 mg U/L and low bicarbonate content of 120 mg/L). No breakthrough was observed for the Fe 0 columns with effluent uranium con-centrations being below the detection limit of 10 μg/L after treating more than 2,000 pore volumes (PV) and no uranium could be leached from loaded Fe 0 columns with 200 PV of uranium free AGW. However, columns with high Fe 0 content (≥ 50%) suffered from severe loss of permeability when AGW with ≥ 320 mg/L bicarbonate was used. In the HAP columns a breakthrough occurred with effluent uranium concentrations > 15 μg/l after treating 1,240 PV (10% and 50% breakthrough after 1,460 PV and 2,140 PV respectively). 12.2% of the accu-mulated uranium could be desorbed again with 840 PV of uranium free AGW. Adsorption was found to be the dominant reaction mechanism for uranium and HAP. Image analysis of high uranium content samples showed uranium and phosphate bearing crystals growing from HAP surfaces. The uranium phases chernikovite and meta-ankoleite of the autunite group were identified by x-ray diffraction. The existence of these mineral phases proves that surface precipitation also occurs under favourable conditions. No uranium

  4. 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.

  5. 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.

  6. 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.

  7. 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.

  8. 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.

  9. Tidal and Seasonal River Stage Fluctuations Impact the Formation of Permeable Natural Reactive Barriers in Riverbank Sediments

    Science.gov (United States)

    Shuai, P.; Myers, K.; Knappett, P.; Cardenas, M. B.

    2017-12-01

    River stage fluctuations, induced by ocean tides and rainfall, enhance the exchange between oxic river water and reducing groundwater. When mixing occurs within riverbank aquifers high in dissolved iron (Fe) and arsenic (As), the timing and extent of mixing likely control the accumulation and mobility of arsenic (As) within the hyporheic zone. Here we analyzed the impact of tidal and seasonal water level fluctuations on the formation of a Permeable Natural Reactive Barrier (PNRB) within an aquifer adjacent to the Meghna River, Bangladesh and its impact on As mobility. We found that the periodicity and amplitude of river stage fluctuations strongly control the spatial and temporal distribution of the PNRB, comprised of rapidly precipitated iron oxides, in this riverbank along a relatively straight reach of the Meghna River. The PNRB forms much faster and with higher concentration of Fe-oxide under semi-diurnal (12 hr) tidal fluctuations compared to simulations run assuming only neap-spring tides (14 day). As tidal amplitude increases, a larger contact area between oxic river water and reducing groundwater results which in turn leads to the horizontal expansion of the PNRB into the riverbank. Seasonal fluctuations expand the PNRB up to 60 m horizontally and 5 m vertically. In contrast neap-spring tidal fluctuations result in a smaller PNRB that is 10 and 3 m in the horizontal and vertical dimensions. The predicted changes in the spatial distribution of iron oxides within the riverbank would trap and release As at different times of the year. The PNRB could act as a secondary source of As to drinking water aquifers under sustained groundwater pumping scenarios near the river.

  10. Linking field and laboratory studies to investigate nitrate removal using permeable reactive barrier technology during managed recharge

    Science.gov (United States)

    Gorski, G.; Beganskas, S.; Weir, W. B.; Redford, K.; Saltikov, C.; Fisher, A. T.

    2017-12-01

    We present data from a series of field and laboratory studies investigating mechanisms for the enhanced removal of nitrate during infiltration as a part of managed recharge. These studies combine physical, geochemical, and microbiological data collected during controlled infiltration experiments at both a plot and a laboratory scale using permeable reactive barrier (PRB) technology. The presence of a PRB, made of wood chips or biochar, enhances nitrate removal by stimulating the growth and productivity of native soil microbes to process nitrate via denitrification. Earlier work has shown that unamended soil can remove up to 50% of nitrate during infiltration at rates microbiological data show significant population changes below the PRB where most of the cycling occurs. Coupled with isotopic analyses, these results suggest that a PRB expands the range of infiltration rates at which significant nitrate can be removed by microbial activity. Further, nitrate removal occurs at different depths below the biochar and redwood chips, suggesting different mechanisms of nitrate removal in the presence of different PRB materials. In laboratory studies we flowed artificial groundwater through intact sediment cores collected at the same field site where we also ran infiltration tests. These experiments show that the fluid flow rate and the presence of a PRB exhibit primary control on nitrate removal during infiltration, and that the relationship between flow rate and nitrate removal is fundamentally different in the presence of a PRB. These data from multiple scales and flow regimes are combined to offer a deeper understanding how the use of PRB technology during infiltration can help address a significant non-point source issue at the surface-subsurface interface.

  11. Enhanced chitosan beads-supported Fe(0)-nanoparticles for removal of heavy metals from electroplating wastewater in permeable reactive barriers.

    Science.gov (United States)

    Liu, Tingyi; Yang, Xi; Wang, Zhong-Liang; Yan, Xiaoxing

    2013-11-01

    The removal of heavy metals from electroplating wastewater is a matter of paramount importance due to their high toxicity causing major environmental pollution problems. Nanoscale zero-valent iron (NZVI) became more effective to remove heavy metals from electroplating wastewater when enhanced chitosan (CS) beads were introduced as a support material in permeable reactive barriers (PRBs). The removal rate of Cr (VI) decreased with an increase of pH and initial Cr (VI) concentration. However, the removal rates of Cu (II), Cd (II) and Pb (II) increased with an increase of pH while decreased with an increase of their initial concentrations. The initial concentrations of heavy metals showed an effect on their removal sequence. Scanning electron microscope images showed that CS-NZVI beads enhanced by ethylene glycol diglycidyl ether (EGDE) had a loose and porous surface with a nucleus-shell structure. The pore size of the nucleus ranged from 19.2 to 138.6 μm with an average aperture size of around 58.6 μm. The shell showed a tube structure and electroplating wastewaters may reach NZVI through these tubes. X-ray photoelectron spectroscope (XPS) demonstrated that the reduction of Cr (VI) to Cr (III) was complete in less than 2 h. Cu (II) and Pb (II) were removed via predominant reduction and auxiliary adsorption. However, main adsorption and auxiliary reduction worked for the removal of Cd (II). The removal rate of total Cr, Cu (II), Cd (II) and Pb (II) from actual electroplating wastewater was 89.4%, 98.9%, 94.9% and 99.4%, respectively. The findings revealed that EGDE-CS-NZVI-beads PRBs had the capacity to remediate actual electroplating wastewater and may become an effective and promising technology for in situ remediation of heavy metals. Copyright © 2013 Elsevier Ltd. All rights reserved.

  12. FeS-coated sand for removal of arsenic(III) under anaerobic conditions in permeable reactive barriers

    Science.gov (United States)

    Han, Y.-S.; Gallegos, T.J.; Demond, A.H.; Hayes, K.F.

    2011-01-01

    Iron sulfide (as mackinawite, FeS) has shown considerable promise as a material for the removal of As(III) under anoxic conditions. However, as a nanoparticulate material, synthetic FeS is not suitable for use in conventional permeable reactive barriers (PRBs). This study developed a methodology for coating a natural silica sand to produce a material of an appropriate diameter for a PRB. Aging time, pH, rinse time, and volume ratios were varied, with a maximum coating of 4.0 mg FeS/g sand achieved using a pH 5.5 solution at a 1:4 volume ratio (sand: 2 g/L FeS suspension), three days of aging and no rinsing. Comparing the mass deposited on the sand, which had a natural iron-oxide coating, with and without chemical washing showed that the iron-oxide coating was essential to the formation of a stable FeS coating. Scanning electron microscopy images of the FeS-coated sand showed a patchwise FeS surface coating. X-ray photoelectron spectroscopy showed a partial oxidation of the Fe(II) to Fe(III) during the coating process, and some oxidation of S to polysulfides. Removal of As(III) by FeS-coated sand was 30% of that by nanoparticulate FeS at pH 5 and 7. At pH 9, the relative removal was 400%, perhaps due to the natural oxide coating of the sand or a secondary mineral phase from mackinawite oxidation. Although many studies have investigated the coating of sands with iron oxides, little prior work reports coating with iron sulfides. The results suggest that a suitable PRB material for the removal of As(III) under anoxic conditions can be produced through the deposition of a coating of FeS onto natural silica sand with an iron-oxide coating. ?? 2010 Elsevier Ltd.

  13. Feasibility Of Coupling Permeable Bio-Barriers And Electrokinetics For The Treatment Of Diesel Hydrocarbons Polluted Soils

    International Nuclear Information System (INIS)

    Ramírez, Esperanza Mena; Jiménez, Cristina Sáez; Camacho, José Villaseñor; Rodrigo, Manuel A.Rodrigo; Cañizares, Pablo

    2015-01-01

    Highlights: • Electrokinetics and a biobarrier were combined to remediate of a diesel polluted soil. • pH gradients did not affect the biobarrier activity located in soil central position. • Microorganisms were partially detached from the biobarrier and moved across the soil. • An anionic surfactant helped the contact between pollutant and microorganisms. • A 39% of the diesel biodegradable fraction was homogeneously removed across the soil. - Abstract: In this study, the remediation of a diesel hydrocarbon-polluted clay soil using an electrochemical-biological combined technology is assessed. The polluted soil was subjected to an electrokinetic (EK) treatment with a biological permeable reactive barrier. A lab-scale electrochemical cell for soil treatment was used. The biological barrier placed in the soil was a biofilm reactor previously adapted for diesel degradation. A batch experiment of 336 h was conducted in a synthetic clay soil spiked with 10 g·kg −1 of diesel and a constant voltage gradient of 1.0 V cm −1 . Sodium dodecyl sulphate was used as an anionic surfactant in the cathodic well to allow for hydrocarbon emulsification during the treatment. At the end of the experiment, extreme pH values were observed near the electrodes. However, the pH remained constant at approximately 7.7 in the central biobarrier zone, which allowed for biological processes. Biological growth was observed in the biobarrier, and a part of the biofilm was detached and transported through the soil in both directions. Furthermore, the surfactant was transported across the soil due to electromigration and electroosmosis, which resulted in diesel emulsification. The combination of biological and EK phenomena finally resulted in a homogenous hydrocarbon removal of approximately 27% in the polluted soil, which indicated a 39% removal of the diesel biodegradable fraction. Due to the electroosmotic flow and the biological degradation, some of the water, surfactant and

  14. Small Is Big: Interactive Trumps Passive Information in Breaking Information Barriers and Impacting Behavioral Antecedents.

    Science.gov (United States)

    Beck, Ariane L; Lakkaraju, Kiran; Rai, Varun

    2017-01-01

    The wealth of information available on seemingly every topic creates a considerable challenge both for information providers trying to rise above the noise and discerning individuals trying to find relevant, trustworthy information. We approach this information problem by investigating how passive versus interactive information interventions can impact the antecedents of behavior change using the context of solar energy adoption, where persistent information gaps are known to reduce market potential. We use two experiments to investigate the impact of both passive and interactive approaches to information delivery on the antecedents (attitudes, subjective norms, and perceived behavioral control in the Theory of Planned Behavior) of intentions and behavior, as well as their effect on intentions and behavior directly. The passive information randomized control trial delivered via Amazon Mechanical Turk tests the effectiveness of delivering the same content in a single message versus multiple shorter messages. The interactive information delivery uses an online (mobile and PC) trivia-style gamification platform. Both experiments use the same content and are carried out over a two-week time period. Our findings suggest that interactive, gamified information has greater impact than passive information, and that shorter multiple messages of passive information are more effective than a single passive message.

  15. 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.

  16. Laboratory studies and model simulations of sorbent material behavior for an in-situ passive treatment barrier

    International Nuclear Information System (INIS)

    Aloysius, D.; Fuhrmann, M.

    1995-01-01

    This paper presents a study combining laboratory experiments and model simulations in support of the design and construction of a passive treatment barrier (or filter wall) for retarding the migration of Sr-90 within a water-bearing surficial sand and gravel layer. Preliminary evaluation was used to select materials for column testing. A one-dimensional finite-difference model was used to simulate the laboratory column results and extrapolation of the calibrated model was then used to assess barrier performance over extended time frames with respect to Sr-90 breakthrough and loading on the filter media. The final results of the study showed that 20 by 50 mesh clinoptilolite will attenuate Sr-90 with a maximum life expentancy of approximately 10 years. This time period is based on allowable limits of Sr-90 activity on the filter media and is also a function of site-specific conditions

  17. Effect of La doping on interface barrier between Si-passivated Ge and insulating HfO{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Kolomiiets, Nadiia M.; Afanas' ev, Valery V.; Madia, Oreste; Stesmans, Andre [Department of Physics and Astronomy, University of Leuven, Celestijnenlaan 200D, 3001 Leuven (Belgium); Cott, Daire J.; Collaert, Nadine [Imec, Kapeldreef 75, 3001 Leuven (Belgium); Thean, Aaron [Imec, Kapeldreef 75, 3001 Leuven (Belgium); National University of Singapore (Singapore)

    2016-12-15

    By analyzing internal photoemission of electrons from Si/SiO{sub x}-passivated Ge into insulating HfO{sub 2} we found that insertion of additional La interlayer between SiO{sub x} and HfO{sub 2} leads to dramatic increase (more than by factor of 20) of the barrier transparency. However, no measurable variation of the interface barrier height is observed suggesting that La induces intermixing of near-interface oxide stack resulting in development of additional density of states corresponding to conduction band of LaO{sub x} and HfO{sub x} sub-networks. At the same time, photoemission results indicate the presence of discrete positive charges in the near-interface oxide layer which may explain the observed ∝1 V shift of capacitance-voltage curves. (copyright 2016 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  18. 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.

  19. In-situ treatment of a mixed hydrocarbon plume through a permeable reactive barrier and enhanced bio-remediation

    International Nuclear Information System (INIS)

    Aglietto, I.; Bretti, L.L.

    2005-01-01

    Groundwater is frequently polluted with mixtures of contaminants that are amenable to different types of remediation. One example is the combination of petroleum hydrocarbons (mostly BTEX) and chlorinated solvents (chlorinated ethenes and propanes), as it occurs in the groundwater beneath the industrial site that is the objective of the present case study. The site is located in Italy near a main river (Arno), which is supposed to be the final recipient of the contamination and where a possible exposure might take place. The aim of the treatment is the plume containment within the site boundaries in order to avoid further migration of the contaminants towards the river. The design of the remediation system was based on an extensive site characterization that included - but was not limited to - the following information: geological and geochemical, microbiological and hydrological data, together with analytical data (i.e. contaminant concentrations). Pilot tests were also implemented in order to collect the necessary parameters for the full-scale treatment design and calibration. The site was contaminated by a mixed plume of more than 30 different contaminants, ranging from BTEX, to MTBE, to PAH, to chlorinated solvents. The concentration peaks were in the order of 1-100 mg/l for each contaminant. Petroleum hydrocarbons are quickly degradable through oxidative mechanisms (especially aerobic biodegradation), whereas fully-chlorinated compounds are only degradable via reductive pathways. A mixed plume of both types of contaminants therefore requires a combined approach with the application of different treatment technologies. The remediation strategy elaborated combines a permeable reactive barrier (PRB) in a funnel and gate configuration for the down-gradient plume containment, with the enhanced bio-remediation of the contaminants for the control of the plume boundaries and for the abatement of the concentration peaks. Pilot tests were carried out in order to assess

  20. 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.

  1. 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

  2. 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.

  3. Determination of equilibrium factor between radon and its progeny using surface barrier detector for various shapes of passive radon dosimeters

    Energy Technology Data Exchange (ETDEWEB)

    Jamil, K. [PINSTECH, Islamabad (Pakistan). Environ. Radiat. Group; Fazal-ur-Rehman [PINSTECH, Islamabad (Pakistan). Environ. Radiat. Group; Ali, S. [PINSTECH, Islamabad (Pakistan). Environ. Radiat. Group; Khan, H.A. [PINSTECH, Islamabad (Pakistan). Environ. Radiat. Group

    1997-03-21

    In the field of radon dosimetry, it is customary to measure radon ({sup 222}Rn) concentration while potential health hazard is due to the radon short-lived progeny. When radon is in secular equilibrium, the measured activity of radon equals the activity of radon`s progeny. However, in practical cases an inequilibrium between radon and its progeny exists which is measured in terms of the equilibrium factor. To determine the equilibrium factor between radon and its progeny in a closed environment various shapes of passive dosimeters based upon solid state nuclear track detectors (SSNTDs) are employed. In order to observe the dependence of equilibrium factor upon shapes or effective volumes, experiments have been performed replacing the SSNTDs with a surface barrier detector in Karlsruhe diffusion chamber, pen-type and box-type dosimeters. Using the collected alpha spectra, the equilibrium factor has been determined for a radon-air mixture in a custom designed radon chamber simulating a closed environment of a room. The results show that the radon equilibrium factor is about 0.20 for different shapes of dosimeters studied in this research. It is concluded that the determination of equilibrium factor between radon and its progeny does not depend upon effective volume or shape of the passive dosimeters using alpha spectroscopic data acquired by surface barrier detector. (orig.).

  4. Determination of equilibrium factor between radon and its progeny using surface barrier detector for various shapes of passive radon dosimeters

    International Nuclear Information System (INIS)

    Jamil, K.; Fazal-ur-Rehman; Ali, S.; Khan, H.A.

    1997-01-01

    In the field of radon dosimetry, it is customary to measure radon ( 222 Rn) concentration while potential health hazard is due to the radon short-lived progeny. When radon is in secular equilibrium, the measured activity of radon equals the activity of radon's progeny. However, in practical cases an inequilibrium between radon and its progeny exists which is measured in terms of the equilibrium factor. To determine the equilibrium factor between radon and its progeny in a closed environment various shapes of passive dosimeters based upon solid state nuclear track detectors (SSNTDs) are employed. In order to observe the dependence of equilibrium factor upon shapes or effective volumes, experiments have been performed replacing the SSNTDs with a surface barrier detector in Karlsruhe diffusion chamber, pen-type and box-type dosimeters. Using the collected alpha spectra, the equilibrium factor has been determined for a radon-air mixture in a custom designed radon chamber simulating a closed environment of a room. The results show that the radon equilibrium factor is about 0.20 for different shapes of dosimeters studied in this research. It is concluded that the determination of equilibrium factor between radon and its progeny does not depend upon effective volume or shape of the passive dosimeters using alpha spectroscopic data acquired by surface barrier detector. (orig.)

  5. 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.

  6. Contamination movement around a permeable reactive barrier at Solid Waste Management Unit 12, Naval Weapons Station Charleston, North Charleston, South Carolina, 2009

    Science.gov (United States)

    Vroblesky, Don A.; Petkewich, Matthew D.; Conlon, Kevin J.

    2010-01-01

    The U.S. Geological Survey and the Naval Facilities Engineering Command Southeast investigated natural and engineered remediation of chlorinated volatile organic compound groundwater contamination at Solid Waste Management Unit 12 at the Naval Weapons Station Charleston, North Charleston, South Carolina, beginning in 2000. In early 2004, groundwater contaminants began moving around the southern end of a permeable reactive barrier (PRB) installed by a consultant in December 2002. The PRB is a 130-foot-long and 3-foot-wide barrier consisting of varying amounts of zero-valent iron with or without sand mixture. Contamination moving around the PRB probably has been transported at least 75 feet downgradient from the PRB at a rate of about 15 to 29 feet per year.

  7. Diabetic and sympathetic influences on the water permeability barrier function of human skin as measured using transepidermal water loss: A case-control study.

    Science.gov (United States)

    Han, Seung Hoon; Park, Ji Woong

    2017-11-01

    The presence of long-standing hyperglycemic conditions has been suggested to lead to many skin problems associated with an impaired skin barrier function. However, the relationship between impaired skin barrier status and altered peripheral nervous system function has not yet been determined. The purpose of this study was to investigate the water evaporation rate as a measure of the permeability barrier function of diabetic skin and its relationship to diabetic sensorimotor polyneuropathy (DSPN) and peripheral autonomic neuropathy (PAN) using well-controlled confounding variables.This case-control study included 42 participants with chronic diabetes and 43 matched healthy controls. The diabetic group underwent a nerve conduction study and sympathetic skin response (SSR) test to confirm the presence of DSPN and PAN, respectively. Different skin regions were analyzed using the noninvasive Tewameter instrument (Courage + Khazaka Electronic GmbH, Cologne, Germany). The impacts of PAN, DSPN, age, and diabetes duration on the values of transepidermal water loss (TEWL) were each analyzed and compared between the groups.Regardless of the presence of DSPN or PAN, the TEWL values as measured on the distal extremities were significantly lower in the diabetic group than in the control group. In the diabetic group, participants with abnormal SSR test results showed decreased TEWL values in the finger, sole, and first toe, as compared with participants with normal SSR test results. In the control group, age showed a negative correlation with the TEWL values with respect to some measured regions. However, in the diabetic group, there was no significant correlation between either patient age or diabetes duration and TEWL values.The presence of a long-term hyperglycemic state can reduce the permeability barrier function of the skin, a phenomenon that might be related to the presence of an impaired peripheral sympathetic nervous system, rather than peripheral sensorimotor

  8. 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...

  9. A polymeric micelle magnetic resonance imaging (MRI) contrast agent reveals blood-brain barrier (BBB) permeability for macromolecules in cerebral ischemia-reperfusion injury.

    Science.gov (United States)

    Shiraishi, Kouichi; Wang, Zuojun; Kokuryo, Daisuke; Aoki, Ichio; Yokoyama, Masayuki

    2017-05-10

    Blood-brain barrier (BBB) opening is a key phenomenon for understanding ischemia-reperfusion injuries that are directly linked to hemorrhagic transformation. The recombinant human tissue-type plasminogen activator (rtPA) increases the risk of symptomatic intracranial hemorrhages. Recent imaging technologies have advanced our understanding of pathological BBB disorders; however, an ongoing challenge in the pre-"rtPA treatment" stage is the task of developing a rigorous method for hemorrhage-risk assessments. Therefore, we examined a novel method for assessment of rtPA-extravasation through a hyper-permeable BBB. To examine the image diagnosis of rtPA-extravasation for a rat transient occlusion-reperfusion model, in this study we used a polymeric micelle MRI contrast-agent (Gd-micelles). Specifically, we used two MRI contrast agents at 1h after reperfusion. Gd-micelles provided very clear contrast images in 15.5±10.3% of the ischemic hemisphere at 30min after i.v. injection, whereas a classic gadolinium chelate MRI contrast agent provided no satisfactorily clear images. The obtained images indicate both the hyper-permeable BBB area for macromolecules and the distribution area of macromolecules in the ischemic hemisphere. Owing to their large molecular weight, Gd-micelles remained in the ischemic hemisphere through the hyper-permeable BBB. Our results indicate the feasibility of a novel clinical diagnosis for evaluating rtPA-related hemorrhage risks. Copyright © 2017 Elsevier B.V. All rights reserved.

  10. 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.

  11. Using dissolved gas analysis to investigate the performance of an organic carbon permeable reactive barrier for the treatment of mine drainage

    Science.gov (United States)

    Williams, R.L.; Mayer, K.U.; Amos, R.T.; Blowes, D.W.; Ptacek, C.J.; Bain, J.G.

    2007-01-01

    The strongly reducing nature of permeable reactive barrier (PRB) treatment materials can lead to gas production, potentially resulting in the formation of gas bubbles and ebullition. Degassing in organic C based PRB systems due to the production of gases (primarily CO2 and CH4) is investigated using the depletion of naturally occurring non-reactive gases Ar and N2, to identify, confirm, and quantify chemical and physical processes. Sampling and analysis of dissolved gases were performed at the Nickel Rim Mine Organic Carbon PRB, which was designed for the treatment of groundwater contaminated by low quality mine drainage characterized by slightly acidic pH, and elevated Fe(II) and SO4 concentrations. A simple 4-gas degassing model was used to analyze the dissolved gas data, and the results indicate that SO4 reduction is by far the dominant process of organic C consumption within the barrier. The data provided additional information to delineate rates of microbially mediated SO4 reduction and confirm the presence of slow and fast flow zones within the barrier. Degassing was incorporated into multicomponent reactive transport simulations for the barrier and the simulations were successful in reproducing observed dissolved gas trends.

  12. ROADSIDE BARRIER AND PASSIVE SAFETY OF MOTORCYCLISTS ALONG EXCLUSIVE MOTORCYCLE LANES

    Directory of Open Access Journals (Sweden)

    A.B. IBITOYE

    2007-04-01

    Full Text Available The tremendous increase in number of motorcycles and fatalities in some ASEAN countries is becoming a main concern for the safety of motorcyclists along exclusive motorcycle lanes. The existing w-beam guardrail system along exclusive motorcycle lanes was originally designed to reduce severity of a crash when cars and trucks involve in run-off road accident – but not specifically to protect motorcyclists during such accident. However, the consequences of this guardrail design on the passive safety of motorcyclist have been given little consideration. Thus, Probability of the motorcyclists getting injured on collision with guardrail is higher compared to other motor vehicle’s driver. In order to investigate the passive safety of motorcyclists while in collision with this guardrail, this study carried out computer simulation of typical crash scenario and conducted a physical crash test to validate the simulation model. The study examines the crash mechanism as related to injury severity when motorcyclist interacts with W-beam guardrail. A three-dimensional computer simulation of a scaled Hybrid III 50th percentile Male dummy mounted on a motorcycle and colliding with W-beam guardrail was carried out. Multi-body model of motorcycle and finite element model of guardrail were developed with commercially available software called MADYMO. The simulation model is validated with a simple crash test conducted with same initial impact configuration. The subsequent simulations were set up for impacting the existing w-beam guardrail with 110 kg motorcycle using eighteen impact conditions that consist of impact angles 15o, 30o and 45o, impact speeds of 32, 48 and 60km/h as well as post spacing of 2m and 4m. The predicted rider’s injury risk criteria were used to assess safety of guardrail response to motorcyclists. The obtained results confirmed that the existing w-beam guardrail is not safe to motorcyclist, especially for the head injury at impact speed

  13. Minoxidil sulfate induced the increase in blood-brain tumor barrier permeability through ROS/RhoA/PI3K/PKB signaling pathway.

    Science.gov (United States)

    Gu, Yan-ting; Xue, Yi-xue; Wang, Yan-feng; Wang, Jin-hui; Chen, Xia; ShangGuan, Qian-ru; Lian, Yan; Zhong, Lei; Meng, Ying-nan

    2013-12-01

    Adenosine 5'-triphosphate-sensitive potassium channel (KATP channel) activator, minoxidil sulfate (MS), can selectively increase the permeability of the blood-tumor barrier (BTB); however, the mechanism by which this occurs is still under investigation. Using a rat brain glioma (C6) model, we first examined the expression levels of occludin and claudin-5 at different time points after intracarotid infusion of MS (30 μg/kg/min) by western blotting. Compared to MS treatment for 0 min group, the protein expression levels of occludin and claudin-5 in brain tumor tissue of rats showed no changes within 1 h and began to decrease significantly after 2 h of MS infusion. Based on these findings, we then used an in vitro BTB model and selective inhibitors of diverse signaling pathways to investigate whether reactive oxygen species (ROS)/RhoA/PI3K/PKB pathway play a key role in the process of the increase of BTB permeability induced by MS. The inhibitor of ROS or RhoA or PI3K or PKB significantly attenuated the expression of tight junction (TJ) protein and the increase of the BTB permeability after 2 h of MS treatment. In addition, the significant increases in RhoA activity and PKB phosphorylation after MS administration were observed, which were partly inhibited by N-2-mercaptopropionyl glycine (MPG) or C3 exoenzyme or LY294002 pretreatment. The present study indicates that the activation of signaling cascades involving ROS/RhoA/PI3K/PKB in BTB was required for the increase of BTB permeability induced by MS. Taken together, all of these results suggested that MS might increase BTB permeability in a time-dependent manner by down-regulating TJ protein expression and this effect could be related to ROS/RhoA/PI3K/PKB signal pathway. Copyright © 2013 Elsevier Ltd. All rights reserved.

  14. Altered blood-brain barrier permeability in rats with prehepatic portal hypertension turns to normal when portal pressure is lowered

    Science.gov (United States)

    Eizayaga, Francisco; Scorticati, Camila; Prestifilippo, Juan P; Romay, Salvador; Fernandez, Maria A; Castro, José L; Lemberg, Abraham; Perazzo, Juan C

    2006-01-01

    AIM: To study the blood-brain barrier integrity in prehepatic portal hypertensive rats induced by partial portal vein ligation, at 14 and 40 d after ligation when portal pressure is spontaneously normalized. METHODS: Adult male Wistar rats were divided into four groups: Group I: Sham14d , sham operated; Group II: PH14d , portal vein stenosis; (both groups were used 14 days after surgery); Group III: Sham40d, Sham operated and Group IV: PH40d Portal vein stenosis (Groups II and IV used 40 d after surgery). Plasma ammonia, plasma and cerebrospinal fluid protein and liver enzymes concentrations were determined. Trypan and Evans blue dyes, systemically injected, were investigated in hippocampus to study blood-brain barrier integrity. Portal pressure was periodically recorded. RESULTS: Forty days after stricture, portal pressure was normalized, plasma ammonia was moderately high, and both dyes were absent in central nervous system parenchyma. All other parameters were reestablished. When portal pressure was normalized and ammonia level was lowered, but not normal, the altered integrity of blood-brain barrier becomes reestablished. CONCLUSION: The impairment of blood-brain barrier and subsequent normalization could be a mechanism involved in hepatic encephalopathy reversibility. Hemodynamic changes and ammonia could trigger blood-brain barrier alterations and its reestablishment. PMID:16552803

  15. 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.

  16. Noise alters guinea pig's blood-labyrinth barrier ultrastructure and permeability along with a decrease of cochlear Claudin-5 and Occludin.

    Science.gov (United States)

    Wu, Yong-Xiang; Zhu, Guo-Xia; Liu, Xin-Qin; Sun, Fei; Zhou, Ke; Wang, Shuang; Wang, Chun-Mei; Jia, Jin-Wen; Song, Jian-Tao; Lu, Lian-Jun

    2014-12-24

    Noise exposure (NE) is a severe modern health hazard that induces hearing impairment. However, the noise-induced ultrastructural changes of blood-labyrinth barrier (BLB) and the potential involvements of tight junction proteins (TJP) remain inconclusive. We investigated the effects of NE on not only the ultrastructure of cochlea and permeability of BLB but also the expression of TJP within the guinea pig cochlea. Male albino guinea pigs were exposed to white noise for 4 h or 2 consecutive days (115 dB sound pressure level, 6 hours per day) and the hearing impairments and light microscopic change of BLB were evaluated with auditory brainstem responses (ABR) and the cochlear sensory epithelia surface preparation, respectively. The cochlear ultrastructure and BLB permeability after NE 2d were revealed with transmission electron microscope (TEM) and lanthanum nitrate-tracing techniques, respectively. The potential alterations of TJPs Claudin-5 and Occludin were quantified with immunohistochemistry and western blot. NE induced significant hearing impairment and NE 2d contributed to significant outer hair cell (OHC) loss that is most severe in the first row of outer hair cells. Furthermore, the loosen TJ and an obvious leakage of lanthanum nitrate particles beneath the basal lamina were revealed with TEM. Moreover, a dose-dependent decrease of Claudin-5 and Occludin was observed in the cochlea after NE. All these findings suggest that both decrease of Claudin-5 and Occludin and increased BLB permeability are involved in the pathologic process of noise-induced hearing impairment; however, the causal relationship and underlying mechanisms should be further investigated.

  17. Methamphetamine transiently increases the blood-brain barrier permeability in the hippocampus: role of tight junction proteins and matrix metalloproteinase-9.

    Science.gov (United States)

    Martins, Tânia; Baptista, Sofia; Gonçalves, Joana; Leal, Ermelindo; Milhazes, Nuno; Borges, Fernanda; Ribeiro, Carlos F; Quintela, Oscar; Lendoiro, Elena; López-Rivadulla, Manuel; Ambrósio, António F; Silva, Ana P

    2011-09-09

    Methamphetamine (METH) is a powerful stimulant drug of abuse that has steadily gained popularity worldwide. It is known that METH is highly neurotoxic and causes irreversible damage of brain cells leading to neurological and psychiatric abnormalities. Recent studies suggested that METH-induced neurotoxicity might also result from its ability to compromise blood-brain barrier (BBB) function. Due to the crucial role of BBB in the maintenance of brain homeostasis and protection against toxic molecules and pathogenic organisms, its dysfunction could have severe consequences. In this study, we investigated the effect of an acute high dose of METH (30mg/kg) on BBB permeability after different time points and in different brain regions. For that, young adult mice were sacrificed 1h, 24h or 72h post-METH administration. METH increased BBB permeability, but this effect was detected only at 24h after administration, being therefore a transitory effect. Interestingly, we also found that the hippocampus was the most susceptible brain region to METH, comparing to frontal cortex and striatum. Moreover, in an attempt to identify the key players in METH-induced BBB dysfunction we further investigated potential alterations in tight junction (TJ) proteins and matrix metalloproteinase-9 (MMP-9). METH was able to decrease the protein levels of zonula occludens (ZO)-1, claudin-5 and occludin in the hippocampus 24h post-injection, and increased the activity and immunoreactivity of MMP-9. The pre-treatment with BB-94 (30mg/kg), a matrix metalloproteinase inhibitor, prevented the METH-induced increase in MMP-9 immunoreactivity in the hippocampus. Overall, the present data demonstrate that METH transiently increases the BBB permeability in the hippocampus, which can be explained by alterations on TJ proteins and MMP-9. Copyright © 2011 Elsevier B.V. All rights reserved.

  18. Charge modification of the endothelial surface layer modulates the permeability barrier of isolated rat mesenteric small arteries

    NARCIS (Netherlands)

    van Haaren, Paul M. A.; VanBavel, Ed; Vink, Hans; Spaan, Jos A. E.

    2005-01-01

    We hypothesized that modulation of the effective charge density of the endothelial surface layer ( ESL) results in altered arterial barrier properties to transport of anionic solutes. Rat mesenteric small arteries ( diameter similar to 190 mu m) were isolated, cannulated, perfused, and superfused

  19. Examination of blood-brain barrier permeability in dementia of the Alzheimer type with [68Ga]EDTA and positron emission tomography

    International Nuclear Information System (INIS)

    Schlageter, N.L.; Carson, R.E.; Rapoport, S.I.

    1987-01-01

    Positron emission tomography with [ 68 Ga]ethylenediaminetetraacetic acid ([ 68 Ga]EDTA) was used to examine the integrity of the blood-brain barrier (BBB) in five patients with dementia of the Alzheimer type and in five healthy age-matched controls. Within a scanning time of 90 min, there was no evidence that measurable intravascular tracer entered the brain in either the dementia or the control group. An upper limit for the cerebrovascular permeability-surface area product of [68Ga]EDTA was estimated as 2 X 10(-6) s-1 in both groups. The results provide no evidence for breakdown of the BBB in patients with dementia of the Alzheimer type

  20. Examination of blood-brain barrier permeability in dementia of the Alzheimer type with [68Ga]EDTA and positron emission tomography.

    Science.gov (United States)

    Schlageter, N L; Carson, R E; Rapoport, S I

    1987-02-01

    Positron emission tomography with [68Ga]ethylenediaminetetraacetic acid ([68Ga]EDTA) was used to examine the integrity of the blood-brain barrier (BBB) in five patients with dementia of the Alzheimer type and in five healthy age-matched controls. Within a scanning time of 90 min, there was no evidence that measurable intravascular tracer entered the brain in either the dementia or the control group. An upper limit for the cerebrovascular permeability-surface area product of [68Ga]EDTA was estimated as 2 X 10(-6) s-1 in both groups. The results provide no evidence for breakdown of the BBB in patients with dementia of the Alzheimer type.

  1. Examination of blood-brain barrier permeability in dementia of the Alzheimer type with (68Ga)EDTA and positron emission tomography

    Energy Technology Data Exchange (ETDEWEB)

    Schlageter, N.L.; Carson, R.E.; Rapoport, S.I.

    1987-02-01

    Positron emission tomography with (/sup 68/Ga)ethylenediaminetetraacetic acid ((/sup 68/Ga)EDTA) was used to examine the integrity of the blood-brain barrier (BBB) in five patients with dementia of the Alzheimer type and in five healthy age-matched controls. Within a scanning time of 90 min, there was no evidence that measurable intravascular tracer entered the brain in either the dementia or the control group. An upper limit for the cerebrovascular permeability-surface area product of (68Ga)EDTA was estimated as 2 X 10(-6) s-1 in both groups. The results provide no evidence for breakdown of the BBB in patients with dementia of the Alzheimer type.

  2. Uranium Removal from Groundwater by Permeable Reactive Barrier with Zero-Valent Iron and Organic Carbon Mixtures: Laboratory and Field Studies

    Directory of Open Access Journals (Sweden)

    Borys Kornilovych

    2018-06-01

    Full Text Available Zhovty Vody city, located in south-central Ukraine, has long been an important center for the Ukrainian uranium and iron industries. Uranium and iron mining and processing activities during the Cold War resulted in poorly managed sources of radionuclides and heavy metals. Widespread groundwater and surface water contamination has occurred, which creates a significant risk to drinking water supplies. Hydrogeologic and geochemical conditions near large uranium mine tailings storage facility (TSF were characterized to provide data to locate, design and install a permeable reactive barrier (PRB to treat groundwater contaminated by leachate infiltrating from the TSF. The effectiveness of three different permeable reactive materials was investigated: zero-valent iron (ZVI for reduction, sorption, and precipitation of redox-sensitive oxyanions; phosphate material to transform dissolved metals to less soluble phases; and organic carbon substrates to promote bioremediation processes. Batch and column experiments with Zhovty Vody site groundwater were conducted to evaluate reactivity of the materials. Reaction rates, residence time and comparison with site-specific clean-up standards were determined. Results of the study demonstrate the effectiveness of the use of the PRB for ground water protection near uranium mine TSF. The greatest decrease was obtained using ZVI-based reactive media and the combined media of ZVI/phosphate/organic carbon combinations.

  3. Utilization of coal/biomass fly ash and bentonite as a low permeability barrier for the containment of acid-generating mine tailings

    International Nuclear Information System (INIS)

    Penney, K.; Mohamedelhassan, E.; Catalan, L.J.J.

    2009-01-01

    The control and treatment of acid mine drainage (AMD) in decommissioned mine sites is a major environmental challenge. In general, AMD has a low pH, high acidity, and elevated concentrations of heavy metals. This study investigated the use of coal/biomass fly ash (CBFA) and CBFA/bentonite mixtures as a low permeability seal to contain acid generating mine tailings and treat AMD. Although pure CBFA is effective as a reactive barrier to treat most toxic metals in AMD, its initial hydraulic conductivity exceeds the maximum regulatory requirement of 1 x 10 -7 cm/s. Therefore, 3 cases were investigated, notably CBFA only; CBFA amended with low percentages of bentonite; and layering of CBFA and CBFA amended with bentonite. Practical geoenvironmental applications for low permeability CBFA or bentonite/CBFA mixtures include a cap overlying reactive mine tailings, a containment pond liner, and a core in containment dams and dykes. Mixing 10 per cent by mass bentonite with CBFA decreased the hydraulic conductivity to 1 x 10 -7 cm/s or less throughout the entire permeation by water and AMD. The installation of a layer of pure CBFA upstream of the bentonite/CBFA mixture resulted in a further decrease in hydraulic conductivity over time by preventing the collapse of the bentonite double layer and promoting precipitation of gypsum and ettringite in the CBFA layer. The effluent from all tested bentonite/CBFA barriers met the regulatory requirements for chemical parameters, except for aluminum which was leached from the CBFA. 14 refs., 3 tabs., 10 figs.

  4. Pressure passive cerebral blood flow and breakdown of the blood-brain barrier in experimental fetal asphyxia

    DEFF Research Database (Denmark)

    Lou, H C; Lassen, N A; Tweed, W A

    1979-01-01

    reaching CBF values up to 6 times normal at normal MABP of about 60 to 70 mmHg, and severe ischemia reaching CBF values close to zero in large cortical areas at MABP of 30 mmHg. CVP remained essentially unchanged at 10--15 mmHg. The severe and prolonged asphyxia rendered the blood-brain barrier leaky......Cerebral blood flow (CBF) was studied in non-exteriorized near-term sheep fetuses using the radioactive microsphere technique. By partially occluding the umbilical vessels for a period of 1--1 1/2 hours a progressive and severe asphyxia with a final arterial pH of 6.90 was achieved. Varying...... the mean arterial blood pressure in the fetuses by blood withdrawal or infusion in this state, CBF was measured at different perfusion pressures (mean arterial blood pressure (MABP) minus central venous pressure (CVP)). A passive flow/pressure relationship--loss of autoregulation--was found, with hyperemia...

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

    Directory of Open Access Journals (Sweden)

    Lopalco A

    2015-03-01

    Full Text Available Antonio Lopalco,1–3,* Hazem Ali,1,* Nunzio Denora,3 Erik Rytting1,4,5 1Department of Obstretrics and Gynecology, University of Texas Medical Branch, Galveston, TX, USA; 2Department of Pharmaceutical Chemistry, University of Kansas, Lawrence, KS, USA; 3Department of Pharmacy – Drug Sciences, University of Bari Aldo Moro, Bari, Italy; 4Center for Biomedical Engineering, University of Texas Medical Branch, Galveston, TX, USA; 5Department of Pharmacology and Toxicology, University of Texas Medical Branch, Galveston, TX, USA *These authors contributed equally to this work Abstract: 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

  6. Adrenergic-induced enhancement of brain barrier system permeability to small nonelectrolytes: choroid plexus versus cerebral capillaries

    International Nuclear Information System (INIS)

    Murphy, V.A.; Johanson, C.E.

    1985-01-01

    Acute hypertension induced by adrenergic agents opens up the blood-CSF barrier (choroid plexus) to nonelectrolyte and protein tracers. Sprague-Dawley adult rats anesthetized with ketamine were given an intravenous bolus of either epinephrine (10 micrograms/kg), phenylephrine (100 micrograms/kg), isoproterenol (10 micrograms/kg), or D,L-amphetamine (2 mg/kg). Tracers were injected simultaneously with test agents, and the animals killed 10 min later. Epinephrine raised MABP by 57 mm Hg, to a peak pressure of 160 mm Hg; and it increased the volume of distribution (Vd) of urea, mannitol, and 125 I-bovine serum albumin in CSF by 1.5-, 2.7-, and 30-fold, respectively. There was enhanced uptake by lateral and fourth ventricle choroid plexuses, cerebral cortex, cerebellum, medulla, and thalamus. Phenylephrine also elevated MABP to 160 mm Hg, but it increased permeation of tracers into CSF (and several brain regions) to a lesser extent than epinephrine, attributable to protective vasoconstriction associated with alpha-agonist activity. Ratio analysis of Vd data provides evidence that augmented permeation of nonelectrolyte tracers in acute hypertension occurs predominantly by diffusion rather than vesicular transport. It is postulated that elevated MABP distends the central cores of choroid plexus villi and cerebral capillaries, with resultant stretching and opening of tight junctions in both barrier systems; with less hindrance to diffusion, urea and mannitol are cleared at rates closer to free diffusion. Neither isoproterenol (decreased MABP by 40 mm Hg) nor amphetamine (did not alter MABP) significantly opened the choroid plexus or blood-brain barrier to tracers

  7. Long-term performance monitoring for a permeable reactive barrier at the U.S. Coast Guard Support Center, Elizabeth City, North Carolina.

    Science.gov (United States)

    Puls, R W; Blowes, D W; Gillham, R W

    1999-08-12

    A continuous hanging iron wall was installed in June, 1996, at the U. S. Coast Guard (USCG) Support Center near Elizabeth City, NC, United States, to treat overlapping plumes of chromate and chlorinated solvent compounds. The wall was emplaced using a continuous trenching machine whereby native soil and aquifer sediment was removed and the iron simultaneously emplaced in one continuous excavation and fill operation. To date, there have been seven rounds (November 1996, March 1997, June 1997, September 1997, December 1997, March 1998, and June 1998) of performance monitoring of the wall. At this time, this is the only full-scale continuous 'hanging' wall installed as a permeable reactive barrier to remediate both chlorinated solvent compounds and chromate in groundwater. Performance monitoring entails the following: sampling of 10-5 cm PVC compliance wells and 15 multi-level samplers for the following constituents: TCE, cis-dichloroethylene (c-DCE), vinyl chloride, ethane, ethene, acetylene, methane, major anions, metals, Cr(VI), Fe(II), total sulfides, dissolved H(2), Eh, pH, dissolved oxygen, specific conductance, alkalinity, and turbidity. Electrical conductivity profiles have been conducted using a Geoprobe to verify emplacement of the continuous wall as designed and to locate upgradient and downgradient wall interfaces for coring purposes. Coring has been conducted in November, 1996, in June and September, 1997, and March, 1998, to evaluate the rate of corrosion on the iron surfaces, precipitate buildup (particularly at the upgradient interface), and permeability changes due to wall emplacement. In addition to several continuous vertical cores, angled cores through the 0.6-m thick wall have been collected to capture upgradient and downgradient wall interfaces along approximate horizontal flow paths for mineralogic analyses.

  8. Effects of Pringle maneuver and partial hepatectomy on the pharmacokinetics and blood-brain barrier permeability of sodium fluorescein in rats.

    Science.gov (United States)

    Miah, Mohammad K; Shaik, Imam H; Bickel, Ulrich; Mehvar, Reza

    2015-08-27

    Liver diseases are known to affect the function of remote organs. The aim of the present study was to investigate the effects of Pringle maneuver, which results in hepatic ischemia-reperfusion (IR) injury, and partial hepatectomy (Hx) on the pharmacokinetics and brain distribution of sodium fluorescein (FL), which is a widely used marker of blood-brain barrier (BBB) permeability. Rats were subjected to Pringle maneuver (total hepatic ischemia) for 20 min with (HxIR) or without (IR) 70% hepatectomy. Sham-operated animals underwent laparotomy only. After 15 min or 8h of reperfusion, a single 25-mg/kg dose of FL was injected intravenously and serial (0-30 min) blood and bile and terminal brain samples were collected. Total and free (ultrafiltration) plasma, total brain homogenate, and bile concentrations of FL and/or its glucuronidated metabolite (FL-Glu) were determined by HPLC. Both IR and HxIR caused significant reductions in the biliary excretions of FL and FL-Glu, resulting in significant increases in the plasma AUC of the marker. Additionally, the free fraction of FL in plasma was significantly increased by HxIR. Although the brain concentrations of FL were increased by almost twofold in both IR and HxIR animals, the brain concentrations corrected by the free FL AUC (and not the total AUC) were similar in both groups at either time points. It is concluded that Pringle maneuver and/or partial hepatectomy substantially alters the hepatobiliary disposition, plasma AUC, plasma free fraction, and brain accumulation of FL without altering the BBB permeability to the marker. Copyright © 2015 Elsevier B.V. All rights reserved.

  9. Induction of selective blood-tumor barrier permeability and macromolecular transport by a biostable kinin B1 receptor agonist in a glioma rat model.

    Science.gov (United States)

    Côté, Jérôme; Bovenzi, Veronica; Savard, Martin; Dubuc, Céléna; Fortier, Audrey; Neugebauer, Witold; Tremblay, Luc; Müller-Esterl, Werner; Tsanaclis, Ana-Maria; Lepage, Martin; Fortin, David; Gobeil, Fernand

    2012-01-01

    Treatment of malignant glioma with chemotherapy is limited mostly because of delivery impediment related to the blood-brain tumor barrier (BTB). B1 receptors (B1R), inducible prototypical G-protein coupled receptors (GPCR) can regulate permeability of vessels including possibly that of brain tumors. Here, we determine the extent of BTB permeability induced by the natural and synthetic peptide B1R agonists, LysdesArg(9)BK (LDBK) and SarLys[dPhe(8)]desArg(9)BK (NG29), in syngeneic F98 glioma-implanted Fischer rats. Ten days after tumor inoculation, we detected the presence of B1R on tumor cells and associated vasculature. NG29 infusion increased brain distribution volume and uptake profiles of paramagnetic probes (Magnevist and Gadomer) at tumoral sites (T(1)-weighted imaging). These effects were blocked by B1R antagonist and non-selective cyclooxygenase inhibitors, but not by B2R antagonist and non-selective nitric oxide synthase inhibitors. Consistent with MRI data, systemic co-administration of NG29 improved brain tumor delivery of Carboplatin chemotherapy (ICP-Mass spectrometry). We also detected elevated B1R expression in clinical samples of high-grade glioma. Our results documented a novel GPCR-signaling mechanism for promoting transient BTB disruption, involving activation of B1R and ensuing production of COX metabolites. They also underlined the potential value of synthetic biostable B1R agonists as selective BTB modulators for local delivery of different sized-therapeutics at (peri)tumoral sites.

  10. Induction of selective blood-tumor barrier permeability and macromolecular transport by a biostable kinin B1 receptor agonist in a glioma rat model.

    Directory of Open Access Journals (Sweden)

    Jérôme Côté

    Full Text Available Treatment of malignant glioma with chemotherapy is limited mostly because of delivery impediment related to the blood-brain tumor barrier (BTB. B1 receptors (B1R, inducible prototypical G-protein coupled receptors (GPCR can regulate permeability of vessels including possibly that of brain tumors. Here, we determine the extent of BTB permeability induced by the natural and synthetic peptide B1R agonists, LysdesArg(9BK (LDBK and SarLys[dPhe(8]desArg(9BK (NG29, in syngeneic F98 glioma-implanted Fischer rats. Ten days after tumor inoculation, we detected the presence of B1R on tumor cells and associated vasculature. NG29 infusion increased brain distribution volume and uptake profiles of paramagnetic probes (Magnevist and Gadomer at tumoral sites (T(1-weighted imaging. These effects were blocked by B1R antagonist and non-selective cyclooxygenase inhibitors, but not by B2R antagonist and non-selective nitric oxide synthase inhibitors. Consistent with MRI data, systemic co-administration of NG29 improved brain tumor delivery of Carboplatin chemotherapy (ICP-Mass spectrometry. We also detected elevated B1R expression in clinical samples of high-grade glioma. Our results documented a novel GPCR-signaling mechanism for promoting transient BTB disruption, involving activation of B1R and ensuing production of COX metabolites. They also underlined the potential value of synthetic biostable B1R agonists as selective BTB modulators for local delivery of different sized-therapeutics at (peritumoral sites.

  11. Influence of Surface Passivation on AlN Barrier Stress and Scattering Mechanism in Ultra-thin AlN/GaN Heterostructure Field-Effect Transistors.

    Science.gov (United States)

    Lv, Y J; Song, X B; Wang, Y G; Fang, Y L; Feng, Z H

    2016-12-01

    Ultra-thin AlN/GaN heterostructure field-effect transistors (HFETs) with, and without, SiN passivation were fabricated by the same growth and device processes. Based on the measured DC characteristics, including the capacitance-voltage (C-V) and output current-voltage (I-V) curves, the variation of electron mobility with gate bias was found to be quite different for devices with, and without, SiN passivation. Although the AlN barrier layer is ultra thin (c. 3 nm), it was proved that SiN passivation induces no additional tensile stress and has no significant influence on the piezoelectric polarization of the AlN layer using Hall and Raman measurements. The SiN passivation was found to affect the surface properties, thereby increasing the electron density of the two-dimensional electron gas (2DEG) under the access region. The higher electron density in the access region after SiN passivation enhanced the electrostatic screening for the non-uniform distributed polarization charges, meaning that the polarization Coulomb field scattering has a weaker effect on the electron drift mobility in AlN/GaN-based devices.

  12. 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

  13. 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

  14. Assessment of Blood-Brain Barrier Permeability by Dynamic Contrast-Enhanced MRI in Transient Middle Cerebral Artery Occlusion Model after Localized Brain Cooling in Rats

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Eun Soo [Department of Radiology, Hallym University Sacred Heart Hospital, Hallym University College of Medicine, Anyang 14068 (Korea, Republic of); Lee, Seung-Koo [Department of Radiology, Yonsei University College of Medicine, Seoul 03722 (Korea, Republic of); Kwon, Mi Jung [Department of Pathology, Hallym University Sacred Heart Hospital, Hallym University College of Medicine, Anyang 14068 (Korea, Republic of); Lee, Phil Hye [Department of Neurology, Yonsei University College of Medicine, Seoul 03722 (Korea, Republic of); Ju, Young-Su [Department of Industrial Medicine, Hallym University Sacred Heart Hospital, Hallym University College of Medicine, Anyang 14068 (Korea, Republic of); Yoon, Dae Young [Department of Radiology, Hallym University Kangdong Sacred Heart Hospital, Hallym University College of Medicine, Seoul 05355 (Korea, Republic of); Kim, Hye Jeong [Department of Radiology, Kangnam Sacred Heart Hospital, Hallym University College of Medicine, Seoul 07441 (Korea, Republic of); Lee, Kwan Seop [Department of Radiology, Hallym University Sacred Heart Hospital, Hallym University College of Medicine, Anyang 14068 (Korea, Republic of)

    2016-11-01

    The purpose of this study was to evaluate the effects of localized brain cooling on blood-brain barrier (BBB) permeability following transient middle cerebral artery occlusion (tMCAO) in rats, by using dynamic contrast-enhanced (DCE)-MRI. Thirty rats were divided into 3 groups of 10 rats each: control group, localized cold-saline (20℃) infusion group, and localized warm-saline (37℃) infusion group. The left middle cerebral artery (MCA) was occluded for 1 hour in anesthetized rats, followed by 3 hours of reperfusion. In the localized saline infusion group, 6 mL of cold or warm saline was infused through the hollow filament for 10 minutes after MCA occlusion. DCE-MRI investigations were performed after 3 hours and 24 hours of reperfusion. Pharmacokinetic parameters of the extended Tofts-Kety model were calculated for each DCE-MRI. In addition, rotarod testing was performed before tMCAO, and on days 1-9 after tMCAO. Myeloperoxidase (MPO) immunohisto-chemistry was performed to identify infiltrating neutrophils associated with the inflammatory response in the rat brain. Permeability parameters showed no statistical significance between cold and warm saline infusion groups after 3-hour reperfusion 0.09 ± 0.01 min{sup -1} vs. 0.07 ± 0.02 min{sup -1}, p = 0.661 for K{sup trans}; 0.30 ± 0.05 min{sup -1} vs. 0.37 ± 0.11 min{sup -1}, p = 0.394 for kep, respectively. Behavioral testing revealed no significant difference among the three groups. However, the percentage of MPO-positive cells in the cold-saline group was significantly lower than those in the control and warm-saline groups (p < 0.05). Localized brain cooling (20℃) does not confer a benefit to inhibit the increase in BBB permeability that follows transient cerebral ischemia and reperfusion in an animal model, as compared with localized warm-saline (37℃) infusion group.

  15. Enhancement in blood-tumor barrier permeability and delivery of liposomal doxorubicin using focused ultrasound and microbubbles: evaluation during tumor progression in a rat glioma model

    Science.gov (United States)

    Aryal, Muna; Park, Juyoung; Vykhodtseva, Natalia; Zhang, Yong-Zhi; McDannold, Nathan

    2015-03-01

    Effective drug delivery to brain tumors is often challenging because of the heterogeneous permeability of the ‘blood tumor barrier’ (BTB) along with other factors such as increased interstitial pressure and drug efflux pumps. Focused ultrasound (FUS) combined with microbubbles can enhance the permeability of the BTB in brain tumors, as well as the blood-brain barrier in the surrounding tissue. In this study, dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) was used to characterize the FUS-induced permeability changes of the BTB in a rat glioma model at different times after implantation. 9L gliosarcoma cells were implanted in both hemispheres in male rats. At day 9, 14, or 17 days after implantation, FUS-induced BTB disruption using 690 kHz ultrasound and definity microbubbles was performed in one tumor in each animal. Before FUS, liposomal doxorubicin was administered at a dose of 5.67 mg kg-1. This chemotherapy agent was previously shown to improve survival in animal glioma models. The transfer coefficient Ktrans describing extravasation of the MRI contrast agent Gd-DTPA was measured via DCE-MRI before and after sonication. We found that tumor doxorubicin concentrations increased monotonically (823  ±  600, 1817  ±  732 and 2432  ±  448 ng g-1) in the control tumors at 9, 14 and 17 d. With FUS-induced BTB disruption, the doxorubicin concentrations were enhanced significantly (P benefit from FUS-induced drug enhancement. Corresponding enhancements in Ktrans were found to be variable in large/late-stage tumors and not significantly different than controls, perhaps reflecting the size mismatch between the liposomal drug (~100 nm) and Gd-DTPA (molecular weight: 938 Da; hydrodynamic diameter: ≃2 nm). It may be necessary to use a larger MRI contrast agent to effectively evaluate the sonication-induced enhanced permeabilization in large/late-stage tumors when a large drug carrier such as a liposome is used.

  16. Assessment of Blood-Brain Barrier Permeability by Dynamic Contrast-Enhanced MRI in Transient Middle Cerebral Artery Occlusion Model after Localized Brain Cooling in Rats

    International Nuclear Information System (INIS)

    Kim, Eun Soo; Lee, Seung-Koo; Kwon, Mi Jung; Lee, Phil Hye; Ju, Young-Su; Yoon, Dae Young; Kim, Hye Jeong; Lee, Kwan Seop

    2016-01-01

    The purpose of this study was to evaluate the effects of localized brain cooling on blood-brain barrier (BBB) permeability following transient middle cerebral artery occlusion (tMCAO) in rats, by using dynamic contrast-enhanced (DCE)-MRI. Thirty rats were divided into 3 groups of 10 rats each: control group, localized cold-saline (20℃) infusion group, and localized warm-saline (37℃) infusion group. The left middle cerebral artery (MCA) was occluded for 1 hour in anesthetized rats, followed by 3 hours of reperfusion. In the localized saline infusion group, 6 mL of cold or warm saline was infused through the hollow filament for 10 minutes after MCA occlusion. DCE-MRI investigations were performed after 3 hours and 24 hours of reperfusion. Pharmacokinetic parameters of the extended Tofts-Kety model were calculated for each DCE-MRI. In addition, rotarod testing was performed before tMCAO, and on days 1-9 after tMCAO. Myeloperoxidase (MPO) immunohisto-chemistry was performed to identify infiltrating neutrophils associated with the inflammatory response in the rat brain. Permeability parameters showed no statistical significance between cold and warm saline infusion groups after 3-hour reperfusion 0.09 ± 0.01 min -1 vs. 0.07 ± 0.02 min -1 , p = 0.661 for K trans ; 0.30 ± 0.05 min -1 vs. 0.37 ± 0.11 min -1 , p = 0.394 for kep, respectively. Behavioral testing revealed no significant difference among the three groups. However, the percentage of MPO-positive cells in the cold-saline group was significantly lower than those in the control and warm-saline groups (p < 0.05). Localized brain cooling (20℃) does not confer a benefit to inhibit the increase in BBB permeability that follows transient cerebral ischemia and reperfusion in an animal model, as compared with localized warm-saline (37℃) infusion group

  17. Assessment of blood-brain barrier permeability by dynamic contrast-enhanced MRI in transient middle cerebral artery occlusion model after localized brain cooling in rats

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Eun Soo; Lee, Kwan Seop; Kwon, Mi Jung; Ju, Young Su [Hallym University Sacred Heart Hospital, Hallym University College of Medicine, Anyang (Korea, Republic of); Lee, Seung Koo; Lee, Phil Hye [Yonsei University College of Medicine, Seoul (Korea, Republic of); Yoon, Dae Young [Dept. of Radiology, Hallym University Kangdong Sacred Heart Hospital, Hallym University College of Medicine, Seoul (Korea, Republic of); Kim, Hye Jeong [Dept. of Radiology, Kangnam Sacred Heart Hospital, Hallym University College of Medicine, Seoul (Korea, Republic of)

    2016-09-15

    The purpose of this study was to evaluate the effects of localized brain cooling on blood-brain barrier (BBB) permeability following transient middle cerebral artery occlusion (tMCAO) in rats, by using dynamic contrast-enhanced (DCE)-MRI. Thirty rats were divided into 3 groups of 10 rats each: control group, localized cold-saline (20 .deg. ) infusion group, and localized warm-saline (37 .deg. ) infusion group. The left middle cerebral artery (MCA) was occluded for 1 hour in anesthetized rats, followed by 3 hours of reperfusion. In the localized saline infusion group, 6 mL of cold or warm saline was infused through the hollow filament for 10 minutes after MCA occlusion. DCE-MRI investigations were performed after 3 hours and 24 hours of reperfusion. Pharmacokinetic parameters of the extended Tofts-Kety model were calculated for each DCE-MRI. In addition, rotarod testing was performed before tMCAO, and on days 1-9 after tMCAO. Myeloperoxidase (MPO) immunohisto-chemistry was performed to identify infiltrating neutrophils associated with the inflammatory response in the rat brain. Permeability parameters showed no statistical significance between cold and warm saline infusion groups after 3-hour reperfusion 0.09 ± 0.01 min{sup -1} vs. 0.07 ± 0.02 min{sup -1},p = 0.661 for K{sup trans}; 0.30 ± 0.05 min{sup -1} vs. 0.37 ± 0.11 min{sup -1},p = 0.394 for kep, respectively. Behavioral testing revealed no significant difference among the three groups. However, the percentage of MPO-positive cells in the cold-saline group was significantly lower than those in the control and warm-saline groups (p < 0.05). Localized brain cooling (20 .deg. ) does not confer a benefit to inhibit the increase in BBB permeability that follows transient cerebral ischemia and reperfusion in an animal model, as compared with localized warm-saline (37 .deg. ) infusion group.

  18. Assessment of blood-brain barrier permeability by dynamic contrast-enhanced MRI in transient middle cerebral artery occlusion model after localized brain cooling in rats

    International Nuclear Information System (INIS)

    Kim, Eun Soo; Lee, Kwan Seop; Kwon, Mi Jung; Ju, Young Su; Lee, Seung Koo; Lee, Phil Hye; Yoon, Dae Young; Kim, Hye Jeong

    2016-01-01

    The purpose of this study was to evaluate the effects of localized brain cooling on blood-brain barrier (BBB) permeability following transient middle cerebral artery occlusion (tMCAO) in rats, by using dynamic contrast-enhanced (DCE)-MRI. Thirty rats were divided into 3 groups of 10 rats each: control group, localized cold-saline (20 .deg. ) infusion group, and localized warm-saline (37 .deg. ) infusion group. The left middle cerebral artery (MCA) was occluded for 1 hour in anesthetized rats, followed by 3 hours of reperfusion. In the localized saline infusion group, 6 mL of cold or warm saline was infused through the hollow filament for 10 minutes after MCA occlusion. DCE-MRI investigations were performed after 3 hours and 24 hours of reperfusion. Pharmacokinetic parameters of the extended Tofts-Kety model were calculated for each DCE-MRI. In addition, rotarod testing was performed before tMCAO, and on days 1-9 after tMCAO. Myeloperoxidase (MPO) immunohisto-chemistry was performed to identify infiltrating neutrophils associated with the inflammatory response in the rat brain. Permeability parameters showed no statistical significance between cold and warm saline infusion groups after 3-hour reperfusion 0.09 ± 0.01 min -1 vs. 0.07 ± 0.02 min -1 ,p = 0.661 for K trans ; 0.30 ± 0.05 min -1 vs. 0.37 ± 0.11 min -1 ,p = 0.394 for kep, respectively. Behavioral testing revealed no significant difference among the three groups. However, the percentage of MPO-positive cells in the cold-saline group was significantly lower than those in the control and warm-saline groups (p < 0.05). Localized brain cooling (20 .deg. ) does not confer a benefit to inhibit the increase in BBB permeability that follows transient cerebral ischemia and reperfusion in an animal model, as compared with localized warm-saline (37 .deg. ) infusion group

  19. Differential blood-brain barrier permeabilities to [14C]sucrose and [3H]inulin after osmotic opening in the rat

    International Nuclear Information System (INIS)

    Ziylan, Y.Z.; Robinson, P.J.; Rapoport, S.I.

    1983-01-01

    The blood-brain barrier (B-BB) in 3-month-old rats was opened unilaterally by infusing 1.8 m L(+)arabinose in water into the internal carotid artery through a catheter in the external carotid. Two poorly penetrating uncharged test radiotracers of differing molecular weight and size, [ 14 C]sucrose (340 daltons, radius 5 A) and [ 3 H]inulin (5500 daltons, radius 15 A), were simultaneously injected i.v. in untreated rats, or rats at 1, 30, or 50 min after infusion of hypertonic arabinose solution. Evans-blue solution was injected 5 min prior to osmotic treatment as a visual indicator of barrier integrity. In regions of uninfused control brains, the [ 14 C]sucrose permeability-surface area (PA) product approximated 10(-5) s-1, whereas PA was not measurable for [ 3 H]inulin. In arabinose-infused animals, PA products on the ipsilateral hemisphere for both [ 14 C]sucrose and [ 3 H]inulin were markedly elevated 6 min after infusion, but decreased by 35 and 55 min. In nearly all regions, statistically significant differences were not found between 6-min [ 14 C]sucrose- and [ 3 H]inulin-PA values (P greater than 0.05). However, at 35 and 55 min in most regions, the PA for [ 3 H]inulin was significantly lower (P less than 0.05) than PA for [ 14 C]sucrose. The results indicated that the B-BB closed more rapidly to larger than to smaller molecules after osmotic treatment and were consistent with a pore model for osmotic B-BB opening

  20. In vitro porcine blood-brain barrier model for permeability studies: pCEL-X software pKa(FLUX) method for aqueous boundary layer correction and detailed data analysis.

    Science.gov (United States)

    Yusof, Siti R; Avdeef, Alex; Abbott, N Joan

    2014-12-18

    In vitro blood-brain barrier (BBB) models from primary brain endothelial cells can closely resemble the in vivo BBB, offering valuable models to assay BBB functions and to screen potential central nervous system drugs. We have recently developed an in vitro BBB model using primary porcine brain endothelial cells. The model shows expression of tight junction proteins and high transendothelial electrical resistance, evidence for a restrictive paracellular pathway. Validation studies using small drug-like compounds demonstrated functional uptake and efflux transporters, showing the suitability of the model to assay drug permeability. However, one limitation of in vitro model permeability measurement is the presence of the aqueous boundary layer (ABL) resulting from inefficient stirring during the permeability assay. The ABL can be a rate-limiting step in permeation, particularly for lipophilic compounds, causing underestimation of the permeability. If the ABL effect is ignored, the permeability measured in vitro will not reflect the permeability in vivo. To address the issue, we explored the combination of in vitro permeability measurement using our porcine model with the pKa(FLUX) method in pCEL-X software to correct for the ABL effect and allow a detailed analysis of in vitro (transendothelial) permeability data, Papp. Published Papp using porcine models generated by our group and other groups are also analyzed. From the Papp, intrinsic transcellular permeability (P0) is derived by simultaneous refinement using a weighted nonlinear regression, taking into account permeability through the ABL, paracellular permeability and filter restrictions on permeation. The in vitro P0 derived for 22 compounds (35 measurements) showed good correlation with P0 derived from in situ brain perfusion data (r(2)=0.61). The analysis also gave evidence for carrier-mediated uptake of naloxone, propranolol and vinblastine. The combination of the in vitro porcine model and the software

  1. Development in NMR spiral imaging and application to the assessment of the permeability of the blood-brain barrier on 2 models of brain tumors

    International Nuclear Information System (INIS)

    Beaumont, M.

    2007-12-01

    The results presented in this work were obtained as part of methodological developments in magnetic resonance imaging. First of all, the setting of the rapid imaging technique using a k-space sampling scheme along a variable density spiral is described. Numerical simulations were used to optimize the acquisitions parameters and to compare different reconstruction techniques. An original approach to calibrate the k-space trajectory was proposed. Then, spiral imaging was used to implement a method to measure the blood brain barrier permeability to Gd-DOTA. This protocol was combined to blood volume and vessel size index measurements using Sinerem. The results obtained highlighted differences between the microvascular parameters measured on C6 and RG2 tumor models. The presence of Sinerem induces a mean decrease of the transfer constant across the vascular wall (Ktrans), in the tumor, of 24 per cent. This study also showed extravasation of the Sinerem, during the first two hours after the product injection, only in the RG2 tumors. (author)

  2. Interrelations between blood-brain barrier permeability and matrix metalloproteinases are differently affected by tissue plasminogen activator and hyperoxia in a rat model of embolic stroke

    Directory of Open Access Journals (Sweden)

    Michalski Dominik

    2012-01-01

    Full Text Available Abstract Background In ischemic stroke, blood-brain barrier (BBB regulations, typically involving matrix metalloproteinases (MMPs and inhibitors (TIMPs as mediators, became interesting since tissue plasminogen activator (tPA-related BBB breakdown with risk of secondary hemorrhage was considered to involve these mediators too. Despite high clinical relevance, detailed interactions are purely understood. After a pilot study addressing hyperoxia as potential neuroprotective co-treatment to tPA, we analyzed interrelations between BBB permeability (BBB-P, MMPs and TIMPs. Findings Rats underwent embolic middle cerebral artery occlusion (eMCAO and treatment with normobaric (NBO or hyperbaric oxygen (HBO, tPA, tPA+HBO, or no treatment. BBB-P was assessed by intravenously applied FITC-albumin at 4 or 24 hours. MMP-2/-9 and TIMP-1/-2 serum levels were determined at 5 or 25 hours. Time point-corrected partial correlations were used to explore interrelations of BBB-P in ischemic regions (extra-/intravasal FITC-albumin ratio and related serum markers. BBB-P correlated positively with MMP-2 and MMP-9 in controls, whereas hyperoxia led to an inverse association, most pronounced for HBO/MMP-9 (r = -0.606; P Conclusions HBO was found to reverse the positively directed interrelation of BBB-P and MMPs after eMCAO, but this effect failed to sustain in the expected amount when HBO and tPA were given simultaneously.

  3. Remediation of lead and cadmium from simulated groundwater in loess region in northwestern China using permeable reactive barrier filled with environmentally friendly mixed adsorbents.

    Science.gov (United States)

    Fan, Chunhui; Gao, Yalin; Zhang, Yingchao; Dong, Wanqing; Lai, Miao

    2018-01-01

    Permeable reactive barrier (PRB) is potentially effective for groundwater remediation, especially using environmentally friendly mixed fillers in representative areas, such as semi-arid loess region in northwestern China. The mixed materials, including corn straw (agricultural wastes), fly ash (industrial wastes), zeolite synthesized from fly ash (reutilized products), and iron-manganese nodule derived from loess (materials with regional characteristics) in northwestern China, were chosen as PRB media to reduce the contents of lead and cadmium in simulated groundwater. A series of lab-scale column experiments were investigated, and the response surface methodology (RSM) was used to optimize the working process; Fourier transform infrared spectroscopy (FT-IR) and scanning electron microscope (SEM) were applied to further reveal the reaction mechanism. It shows that the purification efficiencies are more acceptable when the concentrations of lead and cadmium are approximately 7 and 0.7 mg/L, respectively, at 25 °C in weakly acidic solution, and functional groups of -OH and C=C play an important role for contaminants removal. The mixed adsorbents used are effective to remove lead and cadmium in groundwater. This is the first report on the removal of lead and cadmium from groundwater in loess region in northwestern China using PRB filled with environmentally friendly mixed adsorbents.

  4. Remediation of the Highland Drive South Ravine, Port Hope, Ontario: Contaminated Groundwater Discharge Management Using Permeable Reactive Barriers and Contaminated Sediment Removal - 13447

    Energy Technology Data Exchange (ETDEWEB)

    Smyth, David; Roos, Gillian [Golder Associates Ltd., 2390 Argentia Road, Mississauga, ON L5N 5Z7 (Canada); Ferguson Jones, Andrea [MMM Group Ltd., 100 Commerce Valley Drive West, Thornhill, ON L3T 0A1 (Canada); Case, Glenn [AECL Port Hope Area Initiative Management Office, 115 Toronto Road, Port Hope, ON L1A 3S4 (Canada); Yule, Adam [Public Works and Government Services Canada, 4900 Yonge Street, 11th Floor, Toronto, ON, M2N 6A6 (Canada)

    2013-07-01

    The Highland Drive South Ravine (HDSR) is the discharge area for groundwater originating from the Highland Drive Landfill, the Pine Street North Extension (PSNE) roadbed parts of the Highland Drive roadbed and the PSNE Consolidation Site that contain historical low-level radioactive waste (LLRW). The contaminant plume from these LLRW sites contains elevated concentrations of uranium and arsenic and discharges with groundwater to shallow soils in a wet discharge area within the ravine, and directly to Hunt's Pond and Highland Drive South Creek, which are immediately to the south of the wet discharge area. Remediation and environmental management plans for HDSR have been developed within the framework of the Port Hope Project and the Port Hope Area Initiative. The LLRW sites will be fully remediated by excavation and relocation to a new Long-Term Waste Management Facility (LTWMF) as part of the Port Hope Project. It is projected, however, that the groundwater contaminant plume between the remediated LLRW sites and HDSR will persist for several hundreds of years. At the HDSR, sediment remediation within Hunt's Ponds and Highland Drive South Creek, excavation of the existing and placement of clean fill will be undertaken to remove current accumulations of solid-phase uranium and arsenic associated with the upper 0.75 m of soil in the wet discharge area, and permeable reactive barriers (PRBs) will be used for in situ treatment of contaminated groundwater to prevent the ongoing discharge of uranium and arsenic to the area in HDSR where shallow soil excavation and replacement has been undertaken. Bench-scale testing using groundwater from HDSR has confirmed excellent treatment characteristics for both uranium and arsenic using permeable reactive mixtures containing granular zero-valent iron (ZVI). A sequence of three PRBs containing ZVI and sand in backfilled trenches has been designed to intercept the groundwater flow system prior to its discharge to the ground

  5. Remediation of the Highland Drive South Ravine, Port Hope, Ontario: Contaminated Groundwater Discharge Management Using Permeable Reactive Barriers and Contaminated Sediment Removal - 13447

    International Nuclear Information System (INIS)

    Smyth, David; Roos, Gillian; Ferguson Jones, Andrea; Case, Glenn; Yule, Adam

    2013-01-01

    The Highland Drive South Ravine (HDSR) is the discharge area for groundwater originating from the Highland Drive Landfill, the Pine Street North Extension (PSNE) roadbed parts of the Highland Drive roadbed and the PSNE Consolidation Site that contain historical low-level radioactive waste (LLRW). The contaminant plume from these LLRW sites contains elevated concentrations of uranium and arsenic and discharges with groundwater to shallow soils in a wet discharge area within the ravine, and directly to Hunt's Pond and Highland Drive South Creek, which are immediately to the south of the wet discharge area. Remediation and environmental management plans for HDSR have been developed within the framework of the Port Hope Project and the Port Hope Area Initiative. The LLRW sites will be fully remediated by excavation and relocation to a new Long-Term Waste Management Facility (LTWMF) as part of the Port Hope Project. It is projected, however, that the groundwater contaminant plume between the remediated LLRW sites and HDSR will persist for several hundreds of years. At the HDSR, sediment remediation within Hunt's Ponds and Highland Drive South Creek, excavation of the existing and placement of clean fill will be undertaken to remove current accumulations of solid-phase uranium and arsenic associated with the upper 0.75 m of soil in the wet discharge area, and permeable reactive barriers (PRBs) will be used for in situ treatment of contaminated groundwater to prevent the ongoing discharge of uranium and arsenic to the area in HDSR where shallow soil excavation and replacement has been undertaken. Bench-scale testing using groundwater from HDSR has confirmed excellent treatment characteristics for both uranium and arsenic using permeable reactive mixtures containing granular zero-valent iron (ZVI). A sequence of three PRBs containing ZVI and sand in backfilled trenches has been designed to intercept the groundwater flow system prior to its discharge to the ground surface

  6. Sialic acid (SA)-modified selenium nanoparticles coated with a high blood-brain barrier permeability peptide-B6 peptide for potential use in Alzheimer's disease.

    Science.gov (United States)

    Yin, Tiantian; Yang, Licong; Liu, Yanan; Zhou, Xianbo; Sun, Jing; Liu, Jie

    2015-10-01

    The blood-brain barrier (BBB) is a formidable gatekeeper toward exogenous substances, playing an important role in brain homeostasis and maintaining a healthy microenvironment for complex neuronal activities. However, it also greatly hinders drug permeability into the brain and limits the management of brain diseases. The development of new drugs that show improved transport across the BBB represents a promising strategy for Alzheimer's disease (AD) intervention. Whereas, previous study of receptor-mediated endogenous BBB transport systems has focused on a strategy of using transferrin to facilitate brain drug delivery system, a system that still suffers from limitations including synthesis procedure, stability and immunological response. In the present study, we synthetised sialic acid (SA)-modified selenium (Se) nanoparticles conjugated with an alternative peptide-B6 peptide (B6-SA-SeNPs, a synthetic selenoprotein analogue), which shows high permeability across the BBB and has the potential to serve as a novel nanomedicine for disease modification in AD. Laser-scanning confocal microscopy, flow cytometry analysis and inductively coupled plasma-atomic emission spectroscopy ICP-AES revealed high cellular uptake of B6-SA-SeNPs by cerebral endothelial cells (bEnd.3). The transport efficiency of B6-SA-SeNPs was evaluated in a Transwell experiment based on in vitro BBB model. It provided direct evidence for B6-SA-SeNPs crossing the BBB and being absorbed by PC12 cells. Moreover, inhibitory effects of B6-SA-SeNPs on amyloid-β peptide (Aβ) fibrillation could be demonstrated in PC12 cells and bEnd3 cells. B6-SA-SeNPs could not only effectively inhibit Aβ aggregation but could disaggregate preformed Aβ fibrils into non-toxic amorphous oligomers. These results suggested that B6-SA-SeNPs may provide a promising platform, particularly for the application of nanoparticles in the treatment of brain diseases. Alzheimer's disease (AD) is the world's most common form of

  7. Early intervention with human albumin to reduce the tissue plasminogen activator-mediated blood-brain barrier permeability damaged by delayed reperfusion: an experimental study in rats

    International Nuclear Information System (INIS)

    Lu Haitao; Zhao Jungong; Li Minghua; Li Yongdong; Zhang Peilei

    2011-01-01

    Objective: To clarify whether early use of high-dose human albumin can reduce the permeability of blood-brain barrier (BBB) damaged by delayed thrombolysis or not, and, in tun, reduce the vasogenic brain edema. Methods: A total of 138 male SD rats weighing 320-380 grams were randomly divided into 4 groups: sham operation group (n=3), control group (n=45), albumin group (n=45) and albumin+rt-PA group (n=45). According to the reperfusion time after the onset of middle cerebral artery occlusion (MCAO), each group, except sham operation group, was divided into three subgroups of 2 h, 3 h and 4 h with 15 rats in each subgroup. Rats in albumin group and albumin+rt-PA group received an intravenous infusion of 20% human albumin (2.5 g/kg) 2 hours after the onset of MCAO, and rats in albumin+rt-PA group received an intravenous infusion of rt-PA (10 mg/kg) at all points of reperfusion time via the rat's femoral vein immediately after the reperfusion. All rats were sacrificed 24 hours after MCAO, the infarct volume of the brain was determined with TTC dye method, the leakage extent of BBB was quantitatively estimated by using Evans blue method, and the matrix metalloproteinase-9 (MMP-9) expression was assessed with immunohistochemistry technique. Results: Early intervention with the use of high-dose human albumin could significantly improve the neurological score at 24 h. In MCAO 3 h albumin group, MCAO 4 h albumin group and MCAO 3 h albumin+rt-PA group, neurological score was significantly better than that in the control group (P 0.05). The volume of the infarct tissue was also significantly smaller in all the treated groups with high-dose human albumin groups (P<0.05) when compared with the control group. The infarct volume of the MCAO 4 h in albumin group and albumin+rt-PA group was reduced by 23% and by 17.3%, respectively. Cerebral hemorrhage transformation occurred in two rats of MCAO 4 h control group, in one rat of MCAO 4 h albumin group and in one rat of MCAO 4 h

  8. Ablation of CD11c(hi) dendritic cells exacerbates Japanese encephalitis by regulating blood-brain barrier permeability and altering tight junction/adhesion molecules.

    Science.gov (United States)

    Kim, Jin Hyoung; Hossain, Ferdaus Mohd Altaf; Patil, Ajit Mahadev; Choi, Jin Young; Kim, Seong Bum; Uyangaa, Erdenebelig; Park, Sang-Youel; Lee, John-Hwa; Kim, Bumseok; Kim, Koanhoi; Eo, Seong Kug

    2016-10-01

    Japanese encephalitis (JE), characterized by extensive neuroinflammation following infection with neurotropic JE virus (JEV), is becoming a leading cause of viral encephalitis due to rapid changes in climate and demography. The blood-brain barrier (BBB) plays an important role in restricting neuroinvasion of peripheral leukocytes and virus, thereby regulating the progression of viral encephalitis. In this study, we explored the role of CD11c(hi) dendritic cells (DCs) in regulating BBB integrity and JE progression using a conditional depletion model of CD11c(hi) DCs. Transient ablation of CD11c(hi) DCs resulted in markedly increased susceptibility to JE progression along with highly increased neuro-invasion of JEV. In addition, exacerbated JE progression in CD11c(hi) DC-ablated hosts was closely associated with increased expression of proinflammatory cytokines (IFN-β, IL-6, and TNF-α) and CC chemokines (CCL2, CCL3, CXCL2) in the brain. Moreover, our results revealed that the exacerbation of JE progression in CD11c(hi) DC-ablated hosts was correlated with enhanced BBB permeability and reduced expression of tight junction and adhesion molecules (claudin-5, ZO-1, occluding, JAMs). Ultimately, our data conclude that the ablation of CD11c(hi) DCs provided a subsidiary impact on BBB integrity and the expression of tight junction/adhesion molecules, thereby leading to exacerbated JE progression. These findings provide insight into the secondary role of CD11c(hi) DCs in JE progression through regulation of BBB integrity and the expression of tight junction/adhesion molecules. Copyright © 2016 Elsevier Ltd. All rights reserved.

  9. The proton permeability of self-assembled polymersomes and their neuroprotection by enhancing a neuroprotective peptide across the blood-brain barrier after modification with lactoferrin

    Science.gov (United States)

    Yu, Yuan; Jiang, Xinguo; Gong, Shuyu; Feng, Liang; Zhong, Yanqiang; Pang, Zhiqing

    2014-02-01

    Biotherapeutics such as peptides possess strong potential for the treatment of intractable neurological disorders. However, because of their low stability and the impermeability of the blood-brain barrier (BBB), biotherapeutics are difficult to transport into brain parenchyma via intravenous injection. Herein, we present a novel poly(ethylene glycol)-poly(d,l-lactic-co-glycolic acid) polymersome-based nanomedicine with self-assembled bilayers, which was functionalized with lactoferrin (Lf-POS) to facilitate the transport of a neuroprotective peptide into the brain. The apparent diffusion coefficient (D*) of H+ through the polymersome membrane was 5.659 × 10-26 cm2 s-1, while that of liposomes was 1.017 × 10-24 cm2 s-1. The stability of the polymersome membrane was much higher than that of liposomes. The uptake of polymersomes by mouse brain capillary endothelial cells proved that the optimal density of lactoferrin was 101 molecules per polymersome. Fluorescence imaging indicated that Lf101-POS was effectively transferred into the brain. In pharmacokinetics, compared with transferrin-modified polymersomes and cationic bovine serum albumin-modified polymersomes, Lf-POS obtained the greatest BBB permeability surface area and percentage of injected dose per gram (%ID per g). Furthermore, Lf-POS holding S14G-humanin protected against learning and memory impairment induced by amyloid-β25-35 in rats. Western blotting revealed that the nanomedicine provided neuroprotection against over-expression of apoptotic proteins exhibiting neurofibrillary tangle pathology in neurons. The results indicated that polymersomes can be exploited as a promising non-invasive nanomedicine capable of mediating peptide therapeutic delivery and controlling the release of drugs to the central nervous system.

  10. Management of Animal Carcass Disposal Sites Using a Biochar Permeable Reactive Barrier and Fast Growth Tree (Populus euramericana: A Field Study in Korea

    Directory of Open Access Journals (Sweden)

    Jung-Hwan Yoon

    2017-03-01

    Full Text Available Among many disposal options of animal carcasses due to animal diseases including foot-and-mouth disease (FMD and avian influenza (AI, on-farm burial has been the most frequently used one in Korea. Animal carcasses generate contaminants such as ammonium-N and chloride. This study aimed at testing biochar (BC as a permeable reactive barrier (PRB material in combination with fast growing tree species (Populus euramericana to mitigate groundwater pollution from animal burial sites. For this, a PRB filled with BC was installed and 400 poplar tree (P. euramericana seedlings were planted. Tested BC was obtained from rice husk and its efficiency to mitigate contaminant migration from a burial site of pig carcasses was tested using ammonium-N, chloride, electrical conductivity (EC, and pH as monitoring parameters. Monitoring wells downstream from the burial site were used. Leachates from a monitoring well, three wells inside the burial site close to PRB and three wells outside the burial site close to PRB were sampled and analyzed for ammonium-N, Cl−, EC, and pH for four years from PRB installation. The pH, EC, and ammonium-N of leachate fluctuated during the test period depending on precipitation. pH, EC, and ammonium-N of the leachate samples collected from outside of the burial site close to PRB decreased compared to those from inside of the burial site close to PRB. The concentrations of ammonium-N in the leachate from the monitoring well kept under the threshold value of 10 mg·L−1 for two years from PRB construction. In addition, the growth of poplar plants appeared to be increased via uptaking available N and P released from the burial sites. Achieved results suggest that BC PRBs can be used to in situ mitigate contaminant release from buried animal carcasses.

  11. Remediation of persistent organic pollutant-contaminated soil using biosurfactant-enhanced electrokinetics coupled with a zero-valent iron/activated carbon permeable reactive barrier.

    Science.gov (United States)

    Sun, Yuchao; Gao, Ke; Zhang, Yun; Zou, Hua

    2017-12-01

    Zero-valent iron/activated carbon (Fe/C) particles can degrade persistent organic pollutants via micro-electrolysis and therefore, they may be used to develop materials for permeable reactive barriers (PRBs). In this study, surfactant-enhanced electrokinetics (EK) was coupled with a Fe/C-PRB to treat phenanthrene (PHE) and 2,4,6-trichlorophenol (TCP) co-contaminated clay soil. An environment-friendly biosurfactant, rhamnolipid, was selected as the solubility-enhancing agent. Five bench-scale tests were conducted to investigate the performance of EK-PRB on PHE and TCP removal from soil as well as the impact of pH and rhamnolipid concentration. The results show that both PHE and TCP, driven by electro-osmotic flow (EOF), moved toward the cathode and reacted with the Fe/C-PRB. Catholyte acidification and rhamnolipid concentration increase improved the removal efficiencies of PHE and TCP. The highest removal efficiency of PHE in soil column was five times the efficiency of the control group on which only EK was applied (49.89 versus 9.40%). The highest removal efficiency of TCP in soil column was 4.5 times the efficiency of the control group (64.60 versus 14.30%). Desorption and mobility of PHE and TCP improved with the increase of rhamnolipid concentration when this exceeded the critical micelle concentration. This study indicates that the combination of EK and a Fe/C-PRB is efficient and promising for removing persistent organic pollutants (POPs) from contaminated soil with the enhancement of rhamnolipid.

  12. X-231A demonstration of in-situ remediation of DNAPL compounds in low permeability media by soil fracturing with thermally enhanced mass recovery or reactive barrier destruction

    International Nuclear Information System (INIS)

    Siegrist, R.L.; Slack, W.W.; Houk, T.C.

    1998-03-01

    The overall goal of the program of activities is to demonstrate robust and cost-effective technologies for in situ remediation of DNAPL compounds in low permeability media (LPM), including adaptations and enhancements of conventional technologies to achieve improved performance for DNAPLs in LPM. The technologies sought should be potential for application at simple, small sites (e.g., gasoline underground storage tanks) as well as at complex, larger sites (e.g., DOE land treatment units). The technologies involved in the X-231A demonstration at Portsmouth Gaseous Diffusion Plant (PORTS) utilized subsurface manipulation of the LPM through soil fracturing with thermally enhanced mass recovery or horizontal barrier in place destruction. To enable field evaluation of these approaches, a set of four test cells was established at the X-231A land treatment unit at the DOE PORTS plant in August 1996 and a series of demonstration field activities occurred through December 1997. The principal objectives of the PORTS X-231A demonstration were to: determine and compare the operational features of hydraulic fractures as an enabling technology for steam and hot air enhanced soil vapor extraction and mass recovery, in situ interception and reductive destruction by zero valent iron, and in situ interception and oxidative destruction by potassium permanganate; determine the interaction of the delivered agents with the LPM matrix adjacent to the fracture and within the fractured zone and assess the beneficial modifications to the transport and/or reaction properties of the LPM deposit; and determine the remediation efficiency achieved by each of the technology strategies

  13. microRNA-4516 Contributes to Different Functions of Epithelial Permeability Barrier by Targeting Poliovirus Receptor Related Protein 1 in Enterovirus 71 and Coxsackievirus A16 Infections

    Directory of Open Access Journals (Sweden)

    Yajie Hu

    2018-04-01

    Full Text Available Enterovirus 71 (EV-A71 and coxsackievirus A16 (CV-A16 remain the predominant etiological agents of hand, foot, and mouth disease (HFMD. The clinical manifestations caused by the two viruses are obviously different. CV-A16 usually triggers a repeated infection, and airway epithelial integrity is often the potential causative factor of respiratory repeated infections. Our previous studies have demonstrated that there were some differentially expressed miRNAs involved in the regulation of adhesion function of epithelial barrier in EV-A71 and CV-A16 infections. In this study, we compared the differences between EV-A71 and CV-A16 infections on the airway epithelial barrier function in human bronchial epithelial (16HBE cells and further screened the key miRNA which leaded to the formation of these differences. Our results showed that more rapid proliferation, more serious destruction of 16HBE cells permeability, more apoptosis and disruption of intercellular adhesion-associated molecules were found in CV-A16 infection as compared to EV-A71 infection. Furthermore, we also identified that microRNA-4516 (miR-4516, which presented down-regulation in EV-A71 infection and up-regulation in CV-A16 infection was an important regulator of intercellular junctions by targeting Poliovirus receptor related protein 1(PVRL1. The expressions of PVRL1, claudin4, ZO-1 and E-cadherin in CV-A16-infected cells were significantly less than those in EV-A71-infected cells, while the expressions of these proteins were subverted when pre-treated with miR-4516-overexpression plasmid in EV-A71 infected and miR-4516-knockdown plasmid in CV-A16 infected 16HBE cells. Thus, these data suggested that the opposite expression of miR-4516 in EV-A71 and CV-A16 infections might be the initial steps leading to different epithelial impairments of 16HBE cells by destroying intercellular adhesion, which finally resulted in different outcomes of EV-A71 and CV-A16 infections.

  14. Role of Dissolved Organic Matter and Geochemical Controls on Arsenic Cycling from Sediments to Groundwater along the Meghna River, Bangladesh: Tracking possible links to permeable natural reactive barrier

    Science.gov (United States)

    Datta, S.; Berube, M.; Knappett, P.; Kulkarni, H. V.; Vega, M.; Jewell, K.; Myers, K.

    2017-12-01

    to the overall understanding of geochemical processes involved in As release into groundwaters from sediments within a fluvial deltaic environment and close proximity to a possible permeable natural reactive barrier.

  15. Permeable Reactive Barrier: Technology Update

    Science.gov (United States)

    2011-06-01

    Vukovic 1998; Taylor et al. 2002; Waybrant, Blowes, and Ptacek 1998; Robertson, Vogan, and Lombardo 2008; Hulshof et al. 2003). Solid substrates used...Reductive Dechlorination of Tetrachloroethene to Growth,” Applied Environmental Microbiology 59: 2991–97. Hulshof , A. M. H., D. W. Blowes, C. J

  16. Waste disposal and permeable barriers

    International Nuclear Information System (INIS)

    Richard, S.; Lelievre, D.; Boisson, M.; Usseglio, J.M.; Fargier, E.; Dewiere, L.

    1996-01-01

    A study was made of the hydraulic impact of various concepts with drainage backfill, in order to ascertain the effectiveness of a partial hydraulic Faraday cage. Numerical simulations were developed for modeling the geometrical details of the concepts; a simplified representation of the rock mass was adopted : it was treated as a homogeneous porous medium displaying two major vertical discontinuities, dictating an overall horizontal flow; the validity conditions of this hypothesis for determining the hydraulic effect of drains were discussed; the hydraulic conditions considered are those of the steady state, and in particular, the heating due to waste packages was regarded as negligible (these conditions correspond to long term storage). A theoretical method, based on existing analogies between hydraulic and electrical properties, was also developed and used for a detailed study in the near field of the storage facility. It is shown that boreholes surrounding the storage shaft can limit water circulation in a hundred meter zone forming a partial hydraulic Faraday cage. (author)

  17. Crustal permeability

    Science.gov (United States)

    Gleeson, Tom; Ingebritsen, Steven E.

    2016-01-01

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

  18. 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...

  19. Notional Permeability

    NARCIS (Netherlands)

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

    2012-01-01

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

  20. Installation of a permeable reactive barrier at the mining complex facility in Los Gigantes - Cordoba : Monitoring plan of surface and underground water

    International Nuclear Information System (INIS)

    Grande Cobian, Juan D.; Sanchez Proano, Paula; Cicerone, Daniel S.

    2009-01-01

    The Argentine National Atomic Energy Commission declares under its Environmental policy the commitment to restore those sites where activities concerning Uranium mining were developed. It makes it beyond the scope of the Project of Environmental Restitution of the Uranium Mining (PRAMU from its Spanish abbreviation). The Chemistry of Water and Soil Division at the Environmental Chemistry and Energy Generation Department belonging to the Chemistry Management Office assist the PRAMU on the installation of an hydroxyapatite permeable reactive barrier (PRB) inside the Mining Complex facility placed at Los Gigantes in the Argentine province of Cordoba (in advance named the site). Among the preliminary assessment activities that are being carried out before the installation of the PRB, it has been prepared a monitoring program of surface water and groundwater useful to develop an environmental baseline suitable for the efficiency assessment of the corrective action to be applied. An exploratory campaign was conducted in the site with the aim of establishing a monitoring net of meteorological and hydrological, as well as physical, chemical and biological parameters in matrixes of sediments, water and suspended particulate matter collected on a regular time basis from its surface water and groundwater bodies. The processed results turn into useful environmental information to: a) determine the status of the environmental baseline of the site, b) establish a water quality index (WQI) to manage the natural resource quality according to a rational basis, c) plan experiments related to the design process of a biogenic hydroxyapatite PRB and d) apply chemometric and mechanistic models to forecast the contaminants mobilization through different scenarios and improve the engineering design of the PRB. Once achieved the hydrogeological characterisation of the site and taking into account the originality of the system the following results have been reached: 1) The boundaries of

  1. Alteration behavior of bentonite barrier of radioactive waste disposal by alkaline solutions. Part 2. Effect of type of alkaline solution on permeability of compacted bentonite-sand mixture

    International Nuclear Information System (INIS)

    Yokoyama, Shingo; Nakamura, Kunihiko; Tanaka, Yukihisa; Hironaga, Michihiko

    2011-01-01

    Permeability tests were carried out using compacted bentonite-sand mixture with initial dry density of 1.55 Mg/m 3 and alkaline solutions at 50degC for about two years to estimate the alteration behavior and the change in the permeability. Bentonite-sand mixtures which contain bentonites of 15wt% were made using Na-bentonite or Ca-exchanged bentonite. 0.3M-NaOH solution with pH 13.3 and 5mM-Ca(OH) 2 solution with pH 12.0 were used to the permeability tests of Na-bentonite-sand mixture and of Ca-exchanged bentonite-sand mixture, respectively. In the case of the permeability test conducted using NaOH solution, montmorillonite and other associated minerals were dissolved, and consequently, the dry density and effective montmorillonite density of Na-bentonite-sand mixture were decreased. Furthermore, the mineralogical feature of montmorillonite was changed (i.e. beidellitization and an increase in the layer charge). The permeability of Na-bentonite-sand mixture was increased 5.6 times by the end of permeability test as a result of above alteration. In the case of the permeability test conducted using Ca(OH) 2 solution, montmorillonite and other associated minerals were dissolved, and calcium silicate hydrate (C-S-H) was precipitated. Consequently, the dry density of Ca-exchanged bentonite-sand mixture was increased, while the effective montmorillonite density was decreased. The mineralogical feature of montmorillonite was changed (i.e. beidellitization and an increase in the layer charge). The permeability of Ca-exchange bentonite-sand mixture was decreased by more than two orders of magnitude due to fill the pore of Ca-exchange bentonite-sand mixture by the precipitation of C-S-H. From above results, the type of alkaline solution affects the mineralogical alteration behavior of the compacted bentonite-sand mixture, and consequently, affects the changing trend of permeability. In conclusion, it is important not only to consider the dissolution of montmorillonite, but

  2. Atomic layer deposition of Al{sub 2}O{sub 3} and Al{sub 2}O{sub 3}/TiO{sub 2} barrier coatings to reduce the water vapour permeability of polyetheretherketone

    Energy Technology Data Exchange (ETDEWEB)

    Ahmadzada, Tamkin, E-mail: tahm4852@uni.sydney.edu.au [School of Aerospace, Mechanical and Mechatronic Engineering, University of Sydney, NSW 2006 (Australia); McKenzie, David R.; James, Natalie L.; Yin, Yongbai [School of Physics, University of Sydney, NSW 2006 (Australia); Li, Qing [School of Aerospace, Mechanical and Mechatronic Engineering, University of Sydney, NSW 2006 (Australia)

    2015-09-30

    We demonstrate significantly enhanced barrier properties of polyetheretherketone (PEEK) against water vapour penetration by depositing Al{sub 2}O{sub 3} or Al{sub 2}O{sub 3}/TiO{sub 2} nanofilms grown by atomic layer deposition (ALD). Nanoindentation analysis revealed good adhesion strength of a bilayer Al{sub 2}O{sub 3}/TiO{sub 2} coating to PEEK, while the single layer Al{sub 2}O{sub 3} coating displayed flaking and delamination. We identified three critical design parameters for achieving the optimum barrier properties of ALD Al{sub 2}O{sub 3}/TiO{sub 2} coatings on PEEK. These are a minimum total thickness dependent on the required water vapour transmission rate, the use of an Al{sub 2}O{sub 3}/TiO{sub 2} bilayer coating and the application of the coating to both sides of the PEEK film. Using these design parameters, we achieved a reduction in moisture permeability of PEEK of over two orders of magnitude while maintaining good adhesion strength of the polymer–thin film system. - Highlights: • Atomic layer deposition of Al{sub 2}O{sub 3}/TiO{sub 2} coatings reduced water vapour permeability. • Bilayer coatings reduced the permeability more than single layer coatings. • Bilayer coatings displayed higher adhesion strength than the single layer coatings. • Double-sided coatings performed better than single-sided coatings. • Correlation was found between total thickness and reduced water vapour permeability.

  3. PIWIL1/piRNA-DQ593109 Regulates the Permeability of the Blood-Tumor Barrier via the MEG3/miR-330-5p/RUNX3 Axis

    Directory of Open Access Journals (Sweden)

    Shuyuan Shen

    2018-03-01

    Full Text Available The blood-tumor barrier (BTB restricts the efficient delivery of anti-glioma drugs to cranial glioma tissues. Increased BTB permeability may allow greater delivery of the therapeutic agents. Increasing evidence has revealed that PIWI proteins and PIWI-interacting RNAs (piRNAs play an important role in tumor progression. However, whether PIWI proteins and piRNAs regulate BTB permeability remains unclear. In the present study, we demonstrated that the PIWIL1/piRNA-DQ593109 (piR-DQ593109 complex was the predominant regulator of BTB permeability. Briefly, PIWIL1 was upregulated in glioma endothelial cells (GECs. Furthermore, piR-DQ593109 was also overexpressed in GECs, as revealed via a piRNA microarray. Downregulation of PIWIL1 or piR-DQ593109 increased the permeability of the BTB. Moreover, PIWIL1 and piR-DQ593109, which formed a piRNA-induced silencing complex, degraded the long non-coding RNA maternally expressed 3 (MEG3 in a sequenced-dependent manner. Furthermore, restoring MEG3 released post-transcriptional inhibition of Runt related transcription factor 3 (RUNX3 by sponging miR-330-5p. In addition, RUNX3 bounded to the promoter regions and reduced the promoter activities of ZO-1, occludin, and claudin-5, which significantly impaired the expression levels of ZO-1, occludin, and claudin-5. In conclusion, downregulating PIWIL1 and piR-DQ593109 increased BTB permeability through the MEG3/miR-330-5p/RUNX3 axis. These data may provide insight into glioma treatment.

  4. Surface barrier analysis of semi-insulating and n{sup +}-type GaAs(0 0 1) following passivation with n-alkanethiol SAMs

    Energy Technology Data Exchange (ETDEWEB)

    Marshall, Gregory M. [Laboratory for Quantum Semiconductors and Photon-Based BioNanotechnology, Department of Electrical and Computer Engineering, Universite de Sherbrooke, Sherbrooke, Quebec, J1K 2R1 (Canada); Institute for Chemical Process and Environmental Technology, National Research Council of Canada, Ottawa, Ontario, K1A 0R6 (Canada); Bensebaa, Farid [Institute for Chemical Process and Environmental Technology, National Research Council of Canada, Ottawa, Ontario, K1A 0R6 (Canada); Dubowski, Jan J., E-mail: jan.j.dubowski@usherbrooke.ca [Laboratory for Quantum Semiconductors and Photon-Based BioNanotechnology, Department of Electrical and Computer Engineering, Universite de Sherbrooke, Sherbrooke, Quebec, J1K 2R1 (Canada)

    2011-02-15

    The surface Fermi level of semi-insulating and n{sup +}-type GaAs(0 0 1) was determined before and after passivation with n-alkanethiol self-assembled monolayers (SAMs) by X-ray photoelectron spectroscopy. Fermi level positioning was achieved using Au calibration pads integrated directly onto the GaAs surface, prior to SAM deposition, in order to provide a surface equipotential binding energy reference. Fermi level pinning within 50 meV and surface barrier characteristics according to the Advanced Unified Defect Model were observed. Our results demonstrate the effectiveness of the Au integration technique for the determination of band-edge referenced Fermi level positions and are relevant to an understanding of emerging technologies based on the molecular-semiconductor junction.

  5. Validation of UHPLC-MS/MS methods for the determination of kaempferol and its metabolite 4-hydroxyphenyl acetic acid, and application to in vitro blood-brain barrier and intestinal drug permeability studies.

    Science.gov (United States)

    Moradi-Afrapoli, Fahimeh; Oufir, Mouhssin; Walter, Fruzsina R; Deli, Maria A; Smiesko, Martin; Zabela, Volha; Butterweck, Veronika; Hamburger, Matthias

    2016-09-05

    Sedative and anxiolytic-like properties of flavonoids such as kaempferol and quercetin, and of some of their intestinal metabolites, have been demonstrated in pharmacological studies. However, routes of administration were shown to be critical for observing in vivo activity. Therefore, the ability to cross intestinal and blood-brain barriers was assessed in cell-based models for kaempferol (KMF), and for the major intestinal metabolite of KMF, 4-hydroxyphenylacetic acid (4-HPAA). Intestinal transport studies were performed with Caco-2 cells, and blood-brain barrier transport studies with an immortalized monoculture human model and a primary triple-co-culture rat model. UHPLC-MS/MS methods for KMF and 4-HPAA in Ringer-HEPES buffer and in Hank's balanced salt solution were validated according to industry guidelines. For all methods, calibration curves were fitted by least-squares quadratic regression with 1/X(2) as weighing factor, and mean coefficients of determination (R(2)) were >0.99. Data obtained with all barrier models showed high intestinal and blood-brain barrier permeation of KMF, and no permeability of 4-HPAA, when compared to barrier integrity markers. Copyright © 2016 Elsevier B.V. All rights reserved.

  6. Characteristics of histocompatibility barriers in congenis strains of mice. III. Passive enhancement of skin allografts in x-irradiated hosts

    International Nuclear Information System (INIS)

    Cantrell, J.L.; Kaliss, N.; Hildemann, W.H.

    1975-01-01

    Passive immunological enhancement of skin allografts was investigated in three donor-host combinations of congenic mice disparate at non-H-2 loci. Serum against the graft donor was derived from mice that had received donor strain lymphoid cells as neonates, and thereby were rendered specifically tolerant of a skin allograft. We refer to this serum as ''allograft-tolerant'' serum. Each strain combination was chosen to provide only two non-H-2 histoincompatibilities present in the donor and absent in the host. The differences are categorized as immunogenetically strong, moderate, or weak, on the basis of skin allograft survival times. With passively administered allograft-tolerant serum, significantly prolonged graft survivals were noted for the weakest combination only. Combined treatment with sublethal x-irradiation and allograft-tolerant serum significantly prolonged graft survival in both the moderate and weak combinations, with the largest effect present in the weakest disparity. A hyperimmune alloantiserum (produced in adults) directed against the graft donor prolonged allograft survival in the strongest disparity when given in combination with irradiation. In this combination, graft survival time was increased in hosts exposed to x-ray alone, but joint treatment with x-ray and the alloantiserum gave the largest increment. In contrast, combined treatment with the serum and an antithymocyte alloantiserum did not affect graft survival times. Treatment with both radiation and antithymocyte serum did not prolong graft survival beyond that in mice given only x-radiation. Immunological enhancement with central inhibition is assumed as the mechanism underlying prolonged graft survival, and it is suggested that a population of thymus-derived killer cells, sensitive to x-irradiation, is required for normal graft rejection. (U.S.)

  7. AN IN SITU PERMEABLE REACTIVE BARRIER FOR THE TREATMENT OF HEXAVALENT CHROMIUM AND TRICHLOROETHYLENE IN GROUNDWATER:VOLUME 2 PERFORMANCE MONITORING

    Science.gov (United States)

    A 46 m long, 7.3 m deep, and 0.6 m wide permeable subsurface reactive wall was installed at the U.S. Coast Guard (USCG) Support Center, near Elizabeth City, North Carolina, in June 1996. The reactive wall was designed to remediate hexavalent chromium [Cr(VI)] contaminated ground ...

  8. AN IN-SITU PERMEABLE REACTIVE BARRIER FOR THE TREATMENT OF HEXAVALENT CHROMIUM AND TRICHLOROETHYLENE IN GROUND WATER: VOLUME 1 DESIGN AND INSTALLATION

    Science.gov (United States)

    A 46 m long, 7.3 m deep, and 0.6 m wide permeable subsurface reactive wall was installed at the U.S. Coast Guard (USCG) Support Center, near Elizabeth City, North Carolina, in June 1996. The reactive wall was designed to remediate hexavalent chromium [Cr(VI)] contaminated ground ...

  9. Effect of permeability enhancers on paracellular permeability of acyclovir.

    Science.gov (United States)

    Ates, Muge; Kaynak, Mustafa Sinan; Sahin, Selma

    2016-06-01

    According to Biopharmaceutics Classification System (BCS), acyclovir is a class III (high solubility, low permeability) compound, and it is transported through paracellular route by passive diffusion. The aim of this study was to investigate the effect of various pharmaceutical excipients on the intestinal permeability of acyclovir. The single-pass in-situ intestinal perfusion (SPIP) method was used to estimate the permeability values of acyclovir and metoprolol across different intestinal segments (jejunum, ileum and colon). Permeability coefficient (Peff ) of acyclovir was determined in the absence and presence of a permeation enhancer such as dimethyl β-cyclodextrin (DM-β-CD), sodium lauryl sulfate (SLS), sodium caprate (Cap-Na) and chitosan chloride. All enhancers increased the permeability of paracellularly transported acyclovir. Although Cap-Na has the highest permeability-enhancing effect in all segments, permeation-enhancing effect of chitosan and SLS was only significant in ileum. On the other hand, DM-β-CD slightly decreased the permeability in all intestinal segments. These findings have potential implication concerning the enhancement of absorption of paracellularly transported compounds with limited oral bioavailability. In the case of acyclovir, Cap-Na either alone or in combination with SLS or chitosan has the potential to improve its absorption and bioavailability and has yet to be explored. © 2016 Royal Pharmaceutical Society.

  10. Alteration behavior of bentonite barrier of radioactive waste disposal by alkaline solutions. Part 1. Permeability change of compacted bentonite immersed in alkaline solutions

    International Nuclear Information System (INIS)

    Yokoyama, Shingo; Nakamura, Kunihiko

    2010-01-01

    Permeability tests using the compacted bentonites and alkaline solutions were carried out to estimate of alteration behavior and the change of permeability during the alteration reaction. The permeability tests of the compacted bentonites were carried out at 23degC for one week after they were immersed in alkaline solution at 60degC for four weeks (immersing test). After permeability tests, the compacted bentonites were repeatedly tested as the same procedure (i.e. repetition of permeability test and immersing test) at 11 cycles. The compacted bentonites with initial dry density of 1.6 Mg/m 3 were reacted with the different type of the alkaline solutions (deionized water, NaOH (pH=12 and 14), KOH (pH=12 and 14) and Ca(OH) 2 (pH=12)) in each experiments. In the case of deionized water and alkaline solutions of pH12, the mineral compositions of altered bentonite were similar to original bentonite while the exchangeable cations of altered bentonites were changed. No changes of the mineralogical features of montmorillonite in altered bentonites (i.e. illitization, baideritization and increasing of layer charge) were observed in the case of deionized water, pH12-NaOH and pH12-Ca(OH) 2 . The montmorillonite was changed to the illite/smectite interstratified mineral containing about 40% illite like component during the reaction with pH12-KOH. In the case of alkaline solutions with pH14, the component minerals of bentonite (e.g. montmorillonite, quartz and clinoptilolite) were dissolved, consequently secondly minerals (e.g. analcime and phillipsite) were crystallized during experiments. Furthermore, the mineralogical features of montmorillonite were changed as illitization (pH14-KOH), beidellitization (pH14-NaOH and pH14-KOH) and increasing of layer charge (pH14-NaOH and pH14-KOH). No increasing of permeability were observed during the experiment using pH12-NaOH and pH12-Ca(OH) 2 as well as the case of deionized water. In the case of pH12-KOH, the permeability continually

  11. Effects of agmatine on blood-brain barrier stabilization assessed by permeability MRI in a rat model of transient cerebral ischemia.

    Science.gov (United States)

    Ahn, S S; Kim, S H; Lee, J E; Ahn, K J; Kim, D J; Choi, H S; Kim, J; Shin, N-Y; Lee, S-K

    2015-02-01

    BBB disruption after acute ischemic stroke and subsequent permeability increase may be enhanced by reperfusion. Agmatine has been reported to attenuate BBB disruption. Our aim was to evaluate the effects of agmatine on BBB stabilization in a rat model of transient cerebral ischemia by using permeability dynamic contrast-enhanced MR imaging at early stages and subsequently to demonstrate the feasibility of dynamic contrast-enhanced MR imaging for the investigation of new therapies. Thirty-four male Sprague-Dawley rats were subjected to transient MCA occlusion for 90 minutes. Immediately after reperfusion, agmatine (100 mg/kg) or normal saline was injected intraperitoneally into the agmatine-treated group (n = 17) or the control group, respectively. MR imaging was performed after reperfusion. For quantitative analysis, regions of interest were defined within the infarct area, and values for volume transfer constant, rate transfer coefficient, volume fraction of extravascular extracellular space, and volume fraction of blood plasma were obtained. Infarct volume, infarct growth, quantitative imaging parameters, and numbers of factor VIII-positive cells after immunohistochemical staining were compared between control and agmatine-treated groups. Among the permeability parameters, volume transfer constant and volume fraction of extravascular extracellular space were significantly lower in the agmatine-treated group compared with the control group (0.05 ± 0.02 minutes(-1) versus 0.08 ± 0.03 minute(-1), P = .012, for volume transfer constant and 0.12 ± 0.06 versus 0.22 ± 0.15, P = .02 for volume fraction of extravascular extracellular space). Other permeability parameters were not significantly different between the groups. The number of factor VIII-positive cells was less in the agmatine-treated group than in the control group (3-fold versus 4-fold, P = .037). In ischemic stroke, agmatine protects the BBB, which can be monitored in vivo by quantification of

  12. Mathematical Modeling and Experimental Validation of Nanoemulsion-Based Drug Transport across Cellular Barriers.

    Science.gov (United States)

    Kadakia, Ekta; Shah, Lipa; Amiji, Mansoor M

    2017-07-01

    Nanoemulsions have shown potential in delivering drug across epithelial and endothelial cell barriers, which express efflux transporters. However, their transport mechanisms are not entirely understood. Our goal was to investigate the cellular permeability of nanoemulsion-encapsulated drugs and apply mathematical modeling to elucidate transport mechanisms and sensitive nanoemulsion attributes. Transport studies were performed in Caco-2 cells, using fish oil nanoemulsions and a model substrate, rhodamine-123. Permeability data was modeled using a semi-mechanistic approach, capturing the following cellular processes: endocytotic uptake of the nanoemulsion, release of rhodamine-123 from the nanoemulsion, efflux and passive permeability of rhodamine-123 in aqueous solution. Nanoemulsions not only improved the permeability of rhodamine-123, but were also less sensitive to efflux transporters. The model captured bidirectional permeability results and identified sensitive processes, such as the release of the nanoemulsion-encapsulated drug and cellular uptake of the nanoemulsion. Mathematical description of cellular processes, improved our understanding of transport mechanisms, such as nanoemulsions don't inhibit efflux to improve drug permeability. Instead, their endocytotic uptake, results in higher intracellular drug concentrations, thereby increasing the concentration gradient and transcellular permeability across biological barriers. Modeling results indicated optimizing nanoemulsion attributes like the droplet size and intracellular drug release rate, may further improve drug permeability.

  13. Effects of in Utero Exposure of C57BL/6J Mice to 2,3,7,8-Tetrachlorodibenzo-p-dioxin on Epidermal Permeability Barrier Development and Function

    Science.gov (United States)

    Muenyi, Clarisse S.; Carrion, Sandra Leon; Jones, Lynn A.; Kennedy, Lawrence H.; Slominski, Andrzej T.

    2014-01-01

    Background: Development of the epidermal permeability barrier (EPB) is essential for neonatal life. Defects in this barrier are found in many skin diseases such as atopic dermatitis. Objective: We investigated the effects of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) on the development and function of the EPB. Methods: Timed-pregnant C57BL/6J mice were gavaged with corn oil or TCDD (10 μg/kg body weight) on gestation day 12. Embryos were harvested on embryonic day (E) 15, E16, E17, and postnatal day (PND) 1. Results: A skin permeability assay showed that TCDD accelerated the development of the EPB, beginning at E15. This was accompanied by a significant decrease in transepidermal water loss (TEWL), enhanced stratification, and formation of the stratum corneum (SC). The levels of several ceramides were significantly increased at E15 and E16. PND1 histology revealed TCDD-induced acanthosis and epidermal hyperkeratosis. This was accompanied by disrupted epidermal tight junction (TJ) function, with increased dye leakage at the terminal claudin-1–staining TJs of the stratum granulosum. Because the animals did not have enhanced rates of TEWL, a commonly observed phenotype in animals with TJ defects, we performed tape-stripping. Removal of most of the SC resulted in a significant increase in TEWL in TCDD-exposed PND1 pups compared with their control group. Conclusions: These findings demonstrate that in utero exposure to TCDD accelerates the formation of an abnormal EPB with leaky TJs, warranting further study of environmental exposures, epithelial TJ integrity, and atopic disease. Citation: Muenyi CS, Leon Carrion S, Jones LA, Kennedy LH, Slominski AT, Sutter CH, Sutter TR. 2014. Effects of in utero exposure of C57BL/6J mice to 2,3,7,8-tetrachlorodibenzo-p-dioxin on epidermal permeability barrier development and function. Environ Health Perspect 122:1052–1058; http://dx.doi.org/10.1289/ehp.1308045 PMID:24904982

  14. Essential function of linoleic acid esterified in acylglucosylceramide and acylceramide in maintaining the epidermal water permeability barrier. Evidence from feeding studies with oleate, linoleate, arachidonate, columbinate and a-linolenate

    DEFF Research Database (Denmark)

    Hansen, Harald S.; Jensen, B.

    1985-01-01

    sphingolipids. These rats showed increased evaporation which was comparable to that of essential fatty acid-deficient rats. We interpret these results as strong evidence for a very specific and essential function of linoleic acid in maintaining the integrity of the epidermal water permeability barrier......Essential fatty acid-deficient rats were supplemented with 300 mg per day of pure fatty acid esters: oleate (O), linoleate (L), arachidonate (A), and columbinate (C) for 10 days. During this period, the rats in groups L, A, and C all showed a decrease in their initially high trans-epidermal water...... loss, a classical essential fatty acid-deficiency symptom, to a level seen in non-deficient rats (group N). The trans-epidermal water loss in rats of group O was unaffected by the supplementation. Fatty acid composition of two epidermal sphingolipids, acylglucosylceramide and acylceramide, from...

  15. The Role of miR-330-3p/PKC-α Signaling Pathway in Low-Dose Endothelial-Monocyte Activating Polypeptide-II Increasing the Permeability of Blood-Tumor Barrier

    Directory of Open Access Journals (Sweden)

    Jiahui Liu

    2017-12-01

    Full Text Available This study was performed to determine whether EMAP II increases the permeability of the blood-tumor barrier (BTB by affecting the expression of miR-330-3p as well as its possible mechanisms. We determined the over-expression of miR-330-3p in glioma microvascular endothelial cells (GECs by Real-time PCR. Endothelial monocyte-activating polypeptide-II (EMAP-II significantly decreased the expression of miR-330-3p in GECs. Pre-miR-330-3p markedly decreased the permeability of BTB and increased the expression of tight junction (TJ related proteins ZO-1, occludin and claudin-5, however, anti-miR-330-3p had the opposite effects. Anti-miR-330-3p could enhance the effect of EMAP-II on increasing the permeability of BTB, however, pre-miR-330-3p partly reversed the effect of EMAP-II on that. Similarly, anti-miR-330-3p improved the effects of EMAP-II on increasing the expression levels of PKC-α and p-PKC-α in GECs and pre-miR-330-3p partly reversed the effects. MiR-330-3p could target bind to the 3′UTR of PKC-α. The results of in vivo experiments were similar to those of in vitro experiments. These suggested that EMAP-II could increase the permeability of BTB through inhibiting miR-330-3p which target negative regulation of PKC-α. Pre-miR-330-3p and PKC-α inhibitor decreased the BTB permeability and up-regulated the expression levels of ZO-1, occludin and claudin-5 while anti-miR-330-3p and PKC-α activator brought the reverse effects. Compared with EMAP-II, anti-miR-330-3p and PKC-α activator alone, the combination of the three combinations significantly increased the BTB permeability. EMAP-II combined with anti-miR-330-3p and PKCα activator could enhance the DOX’s effects on inhibiting the cell viabilities and increasing the apoptosis of U87 glioma cells. Our studies suggest that low-dose EMAP-II up-regulates the expression of PKC-α and increases the activity of PKC-α by inhibiting the expression of miR-330-3p, reduces the expression of ZO-1

  16. Permeability of public and private spaces in reproductive healthcare seeking: barriers to uptake of services among low income African American women in a smaller urban setting.

    Science.gov (United States)

    Golden, Annis G

    2014-05-01

    This study was undertaken in partnership with a publicly funded reproductive healthcare organization to better understand barriers to utilization of its services as perceived by low income African American women in its community and how those barriers might be managed. The study uses a place-based, ecological perspective to theorize privacy challenges across different levels of the communication ecology. Analysis of participant observation, interviews, and focus group data identified three key public-private problematics in African American women's experience of reproductive healthcare seeking in a smaller urban setting: a public-private problematic of organizational identity, of organizational regions, and of organizational members. Potential strategies are identified for managing these problematics by the organization and community members. Copyright © 2014. Published by Elsevier Ltd.

  17. PASSIVE CAVITATION DETECTION DURING PULSED HIFU EXPOSURES OF EX VIVO TISSUES AND IN VIVO MOUSE PANCREATIC TUMORS

    OpenAIRE

    Li, Tong; Chen, Hong; Khokhlova, Tatiana; Wang, Yak-Nam; Kreider, Wayne; He, Xuemei; Hwang, Joo Ha

    2014-01-01

    Pulsed high-intensity focused ultrasound (pHIFU) has been demonstrated to enhance vascular permeability, disrupt tumor barriers and enhance drug penetration into tumor tissue through acoustic cavitation. Monitoring of cavitation activity during pHIFU treatments and knowing the ultrasound pressure levels sufficient to reliably induce cavitation in a given tissue are therefore very important. Here, three metrics of cavitation activity induced by pHIFU and evaluated by confocal passive cavitatio...

  18. Passive House Solutions

    Energy Technology Data Exchange (ETDEWEB)

    Strom, I.; Joosten, L.; Boonstra, C. [DHV Sustainability Consultants, Eindhoiven (Netherlands)

    2006-05-15

    PEP stands for 'Promotion of European Passive Houses' and is a consortium of European partners, supported by the European Commission, Directorate General for Energy and Transport. In this working paper an overview is given of Passive House solutions. An inventory has been made of Passive House solutions for new build residences applied in each country. Based on this, the most common basic solutions have been identified and described in further detail, including the extent to which solutions are applied in common and best practice and expected barriers for the implementation in each country. An inventory per country is included in the appendix. The analysis of Passive House solutions in partner countries shows high priority with regard to the performance of the thermal envelope, such as high insulation of walls, roofs, floors and windows/ doors, thermal bridge-free construction and air tightness. Due to the required air tightness, special attention must be paid to indoor air quality through proper ventilation. Finally, efficient ((semi-)solar) heating systems for combined space and DHW heating still require a significant amount of attention in most partner countries. Other basic Passive House solutions show a smaller discrepancy with common practice and fewer barriers have been encountered in partner countries. In the next section, the general barriers in partner countries have been inventoried. For each type of barrier a suggested approach has been given. Most frequently encountered barriers in partner countries are: limited know-how; limited contractor skills; and acceptation of Passive Houses in the market. Based on the suggested approaches to overcoming barriers, this means that a great deal of attention must be paid to providing practical information and solutions to building professionals, providing practical training to installers and contractors and communication about the Passive House concept to the market.

  19. Endothelial Proliferation and Increased Blood - Brain Barrier Permeability in the Basal Ganglia in a Rat Model of 3,4-Dihydrozyphenyl-L-Alanine-Induced Dyskinesia

    DEFF Research Database (Denmark)

    Westin, Jenny E.; Lindgren, Hanna S.; Gardi, Jonathan Eyal

    2006-01-01

    3,4-Dihydroxyphenyl-L-alanine (L-DOPA)-induced dyskinesia is associated with molecular and synaptic plasticity in the basal ganglia, but the occurrence of structural remodeling through cell genesis has not been explored. In this study, rats with 6-hydroxydopamine lesions received injections of th...... of angiogenesis and blood-brain barrier dysfunction in an experimental model of L-DOPA-induced dyskinesia. These microvascular changes are likely to affect the kinetics of L-DOPA entry into the brain, favoring the occurrence of motor complications....... dyskinesia. The vast majority (60-80%) of the newborn cells stained positively for endothelial markers. This endothelial proliferation was associated with an upregulation of immature endothelial markers (nestin) and a downregulation of endothelial barrier antigen on blood vessel walls. In addition......, dyskinetic rats exhibited a significant increase in total blood vessel length and a visible extravasation of serum albumin in the two structures in which endothelial proliferation was most pronounced (substantia nigra pars reticulata and entopeduncular nucleus). The present study provides the first evidence...

  20. Simultaneous estimations of blood brain barrier (BBB) permeability and local cerebral blood volume (CBV) in human brain tumors with positron tomography and Ga-68 EDTA

    International Nuclear Information System (INIS)

    Hawkins, R.A.; Phelps, M.E.; Huang, S.C.; Wapenski, J.A.; Grimm, P.D.; Greenberg, P.; Parker, R.G.; Juillard, G.; Kuhl, D.E.

    1984-01-01

    Using Ga-68 EDTA and a two compartment model for diffusion across the BBB that includes a weighted subtraction term for determination of the relative CBV (compared to a normal region of brain with an intact BBB) or the absolute value of CBV (using measurements of Ga-68 concentrations in the blood: the input function), the authors determined values for the forward and reverse rate constants (k1 and k2) for diffusion across the BBB as well as values of CBV in 12 subjects with primary or metastatic brain tumors. Patients were studied on a NeuroECAT tomograph; imaging times were 1 to 10 minutes per scan for a total of about 2 hours. Measurements of Ga-68 concentrations were made on plasma arterial samples. Four direct measurements (in 3 subjects) of CBV using C(15-0) were also obtained. Values of k1 (the transfer constant which numerically approximates the capillary permeability surface area (PS) product) averaged 0.0030 (+- 0.0017) ml/min/gm while k2 averaged 0.0308 (+- 0.0157)/min. Linear regression analysis of the relative CBV in 7 tumor deposits in 4 paired Ga-68 EDTA/C(15-0) studies compared to normal brain tissues resulted in a correlation coefficient of 0.97 for the two methods. The estimates of k1 and k2 were insensitive to changes in the location of the control regions (although CBV estimates changed appropriately) as well as to substituting the input function for a normal brain region when determining the absolute CBV of the lesions

  1. Passive safety; Passive Sicherheit

    Energy Technology Data Exchange (ETDEWEB)

    Rueckert, J. [Skoda Auto a.s., Mlada Boleslav (Czech Republic). Interieurentwicklung und Versuche; Hau, M. [Skoda Auto a.s., Mlada Boleslav (Czech Republic). Koordination der Fahrzeugsicherung

    2004-05-01

    The specifications for passive safety are partly based on the legal requirements for all export markets combined with the strict internal standards of Volkswagen Group. The Euro NCAP tests and their precisely defined testing methods using the new point assessment are very important. (orig.)

  2. Comparison of Linear and Cyclic His-Ala-Val Peptides in Modulating the Blood-Brain Barrier Permeability: Impact on Delivery of Molecules to the Brain.

    Science.gov (United States)

    Alaofi, Ahmed; On, Ngoc; Kiptoo, Paul; Williams, Todd D; Miller, Donald W; Siahaan, Teruna J

    2016-02-01

    The aim of this study is to evaluate the effect of peptide cyclization on the blood-brain barrier (BBB) modulatory activity and plasma stability of His-Ala-Val peptides, which are derived from the extracellular 1 domain of human E-cadherin. The activities to modulate the intercellular junctions by linear HAV4 (Ac-SHAVAS-NH2), cyclic cHAVc1 (Cyclo(1,8)Ac-CSHAVASC-NH2), and cyclic cHAVc3 (Cyclo(1,6)Ac-CSHAVC-NH2) were compared in in vitro and in vivo BBB models. Linear HAV4 and cyclic cHAVc1 have the same junction modulatory activities as assessed by in vitro MDCK monolayer model and in situ rat brain perfusion model. In contrast, cyclic cHAVc3 was more effective than linear HAV4 in modulating MDCK cell monolayers and in improving in vivo brain delivery of Gd-DTPA on i.v. administration in Balb/c mice. Cyclic cHAVc3 (t1/2 = 12.95 h) has better plasma stability compared with linear HAV4 (t1/2 = 2.4 h). The duration of the BBB modulation was longer using cHAVc3 (2-4 h) compared with HAV4 (brain delivery of IRdye800cw-PEG (25 kDa) as detected by near IR imaging. The result showed that cyclic cHAVc3 peptide had better activity and plasma stability than linear HAV4 peptide. Copyright © 2016 American Pharmacists Association®. Published by Elsevier Inc. All rights reserved.

  3. Ultrastructural studies on the blood-brain barrier. Mainly as to changes in the permeability of cerebral capillary walls induced by experimental x-ray irradiation and the effect of glucocorticoid on such changes

    Energy Technology Data Exchange (ETDEWEB)

    Ichitsubo, H [Tokyo Medical Coll. (Japan)

    1977-03-01

    In the present study, an ultrastructural examination was made of the role of capillary endothelial cells of the brain which is one of the constituent factors of the blood-brain barrier. In normal cerebral capillaries, both endothelial cells and the basement membrane were demonstrated to be not crossed by a tracer (horseradish peroxidase) even in 60 minutes after its intravenous administration, thus suggesting the blood-brain barrier effect. Author investigated changes in the permeability of cerebral capillary walls induced by experimental brain irradiation and the effect of glucocorticoid on such changes. On forty-eight hours following an appropriate irradiation a marked brain edema was developed; under such circumstances when the tracer was injected intravenously, on 60 minutes thereafter the tracer was demonstrated to be transferred into the neutral tissue, and this was interpreted as indicating that capillary hyperpermeability was induced. These findings were suggested that the mechanism of capillary hyperpermeability might not be based on the passage of a tight junction of the cells of capillary wall but rather on account of activated active transport via an increased number of pinocytotic vesicles. The mechanism of increase of pinocytotic vesicle appeared to be resulting from a breakdown of the controlling system of pinocytotic vesicle production. However, the existence of this controlling system is still speculative. Pre-and post-irradiation administration of glucocorticoid proved to be effective in the prevention of irradiation-induced hyperpermeability of cerebral capillaries, and to be indicating the possible usefulness of the drug for the maintenance or repair of the aforementioned system.

  4. Development and validation of a sensitive UPLC-MS/MS method for the quantitation of [(13)C]sucrose in rat plasma, blood, and brain: Its application to the measurement of blood-brain barrier permeability.

    Science.gov (United States)

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

    2016-03-15

    Accurate and reproducible measurement of blood-brain barrier (BBB) integrity is critical in the assessment of the pathophysiology of the central nervous system disorders and in monitoring therapeutic effects. The widely-used low molecular weight marker [(14)C]sucrose is non-specific in the absence of chromatographic separation. The purpose of this study was to develop and validate a sensitive and reproducible LC-MS/MS method for the analysis of stable isotope-modified [(13)C12]sucrose in brain, plasma, and blood to determine BBB permeability to sucrose. After addition of internal standard (IS, [(13)C6]sucrose), the marker and IS were recovered from diluted rat blood, plasma, and brain homogenate by protein precipitation using acetonitrile. The recovery of the marker and IS was almost quantitative (90-106%) for all three matrices. The recovered samples were directly injected into an isocratic UPLC system with a run time of 6 min. Mass spectrometry was conducted using multiple reaction monitoring in negative mode. The method was linear (r(2)≥0.99) in the concentration ranges tested for the diluted blood and plasma (10-1000 ng/mL) and brain homogenate (1-200 ng/mL). The lower limit of quantitation of the assay was 0.5 pg injected on column. The assay was validated (n=5) based on acceptable intra- and inter-run accuracy and precision values. The method was successfully used for the measurement of serial blood and plasma and terminal brain concentrations of [(13)C12]sucrose after a single intravenous dose (10 mg/kg) of the marker to rats. As expected, the apparent brain uptake clearance values of [(13)C12]sucrose were low in healthy rats. The method may be useful for determination of the BBB integrity in animal models. Copyright © 2016 Elsevier B.V. All rights reserved.

  5. West Nile virus-induced cell adhesion molecules on human brain microvascular endothelial cells regulate leukocyte adhesion and modulate permeability of the in vitro blood-brain barrier model.

    Directory of Open Access Journals (Sweden)

    Kelsey Roe

    Full Text Available Characterizing the mechanisms by which West Nile virus (WNV causes blood-brain barrier (BBB disruption, leukocyte infiltration into the brain and neuroinflammation is important to understand the pathogenesis of WNV encephalitis. Here, we examined the role of endothelial cell adhesion molecules (CAMs in mediating the adhesion and transendothelial migration of leukocytes across human brain microvascular endothelial cells (HBMVE. Infection with WNV (NY99 strain significantly induced ICAM-1, VCAM-1, and E-selectin in human endothelial cells and infected mice brain, although the levels of their ligands on leukocytes (VLA-4, LFA-1and MAC-1 did not alter. The permeability of the in vitro BBB model increased dramatically following the transmigration of monocytes and lymphocytes across the models infected with WNV, which was reversed in the presence of a cocktail of blocking antibodies against ICAM-1, VCAM-1, and E-selectin. Further, WNV infection of HBMVE significantly increased leukocyte adhesion to the HBMVE monolayer and transmigration across the infected BBB model. The blockade of these CAMs reduced the adhesion and transmigration of leukocytes across the infected BBB model. Further, comparison of infection with highly neuroinvasive NY99 and non-lethal (Eg101 strain of WNV demonstrated similar level of virus replication and fold-increase of CAMs in HBMVE cells suggesting that the non-neuropathogenic response of Eg101 is not because of its inability to infect HBMVE cells. Collectively, these results suggest that increased expression of specific CAMs is a pathological event associated with WNV infection and may contribute to leukocyte infiltration and BBB disruption in vivo. Our data further implicate that strategies to block CAMs to reduce BBB disruption may limit neuroinflammation and virus-CNS entry via 'Trojan horse' route, and improve WNV disease outcome.

  6. Blood-brain barrier (BBB) toxicity and permeability assessment after L-(4-¹⁰Boronophenyl)alanine, a conventional B-containing drug for boron neutron capture therapy, using an in vitro BBB model.

    Science.gov (United States)

    Roda, E; Nion, S; Bernocchi, G; Coccini, T

    2014-10-02

    Since brain tumours are the primary candidates for treatment by Boron Neutron Capture Therapy, one major challenge in the selective drug delivery to CNS is the crossing of the blood-brain barrier (BBB). The present pilot study investigated (i) the transport of a conventional B-containing product (i.e., L-(4-(10)Boronophenyl)alanine, L-(10)BPA), already used in medicine but still not fully characterized regarding its CNS interactions, as well as (ii) the effects of the L-(10)BPA on the BBB integrity using an in vitro model, consisting of brain capillary endothelial cells co-cultured with glial cells, closely mimicking the in vivo conditions. The multi-step experimental strategy (i.e. Integrity test, Filter study, Transport assay) checked L-(10)BPA toxicity at 80 µg Boron equivalent/ml, and its ability to cross the BBB, additionally by characterizing the cytoskeletal and TJ's proteins by immunocytochemistry and immunoblotting. In conclusion, a lack of toxic effects of L-(10)BPA was demonstrated, nevertheless accompanied by cellular stress phenomena (e.g. vimentin expression modification), paralleled by a low permeability coefficient (0.39 ± 0.01 × 10(-3)cm min(-1)), corroborating the scarce probability that L-(10)BPA would reach therapeutically effective cerebral concentration. These findings emphasized the need for novel strategies aimed at optimizing boron delivery to brain tumours, trying to ameliorate the compound uptake or developing new targeted products suitable to safely and effectively treat head cancer. Thus, the use of in vitro BBB model for screening studies may provide a useful early safety assessment for new effective compounds. Copyright © 2014 Elsevier B.V. All rights reserved.

  7. The permeability of puerarin loaded poly(butylcyanoacrylate) nanoparticles coated with polysorbate 80 on the blood-brain barrier and its protective effect against cerebral ischemia/reperfusion injury.

    Science.gov (United States)

    Zhao, Li-xia; Liu, An-chang; Yu, Shu-wen; Wang, Zeng-xin; Lin, Xiao-qian; Zhai, Guang-xi; Zhang, Qing-zhu

    2013-01-01

    Puerarin (PUE) is a good candidate for treating stroke, but its low concentration in brain after administration limits its curative efficacy. The aim of the present work was to design and characterize PUE loaded poly(butylcyanoacrylate) nanoparticles (PBCN) coated with polysorbate 80 (Ps 80), and to evaluate the effect of PBCN on the permeability of PUE across the blood-brain barrier (BBB) and the effect of PUE loaded PBCN on the cerebral ischemia/reperfusion injury. PUE loaded PBCN were successfully prepared by anionic polymerization method with the mean particle size of 201.2 nm and the zeta potential of -7.72 mV. The in vitro release behavior of PUE from the nanoparticles showed a biphasic profile manner with an initial burst release followed by a sustained release. The results of pharmacokinetic and biodistribution to brain performed in mice after intravenous administration showed that the drug concentrations in blood and brain for PUE loaded PBCN were both greater than these for the free drug. Moreover, compared with free drug, the vein injection of PUE loaded PBCN exerted the better neuroprotective effect in rats with focal cerebral ischemic injury via significantly decreasing neurological deficit scores, increasing body weight, lowing brain water content, and reducing the infarct volume. The results indicated that this preparation may reduce the total dose required for the stroke therapy with concurrent reduction in dose related toxicity. All these findings suggest that PBCN could enhance the transport of PUE to brain and have a potential as a neuroprotective agent in the focal cerebral ischemic injury.

  8. Studies on the optimum conditions using acid-washed zero-valent iron/aluminum mixtures in permeable reactive barriers for the removal of different heavy metal ions from wastewater

    Energy Technology Data Exchange (ETDEWEB)

    Han, Weijiang [School of Environmental Science and Engineering, Guangdong University of Technology, Guangzhou 510006 (China); South China Institute of Environmental Science, MEP, Guangzhou 510655 (China); Fu, Fenglian, E-mail: fufenglian2006@163.com [School of Environmental Science and Engineering, Guangdong University of Technology, Guangzhou 510006 (China); Cheng, Zihang; Tang, Bing; Wu, Shijiao [School of Environmental Science and Engineering, Guangdong University of Technology, Guangzhou 510006 (China)

    2016-01-25

    Highlights: • Acid-washed zero-valent iron and zero-valent aluminum were used in PRBs. • The time that removal efficiencies of heavy metal were above 99.5% can keep 300 h. • Removal mechanism of Cr(VI), Cd{sup 2+}, Ni{sup 2+}, Cu{sup 2+}, and Zn{sup 2+} was discussed. • Heavy metal ions were removed by reduction, adsorption, and co-precipitation. - Abstract: The method of permeable reactive barriers (PRBs) is considered as one of the most practicable approaches in treating heavy metals contaminated surface and groundwater. The mixture of acid-washed zero-valent iron (ZVI) and zero-valent aluminum (ZVAl) as reactive medium in PRBs to treat heavy metal wastewater containing Cr(VI), Cd{sup 2+}, Ni{sup 2+}, Cu{sup 2+}, and Zn{sup 2+} was investigated. The performance of column filled with the mixture of acid-washed ZVI and ZVAl was much better than the column filled with ZVI or ZVAl alone. At initial pH 5.4 and flow rates of 1.0 mL/min, the time that the removal efficiencies of Cr(VI), Cd{sup 2+}, Ni{sup 2+}, Cu{sup 2+}, and Zn{sup 2+} were all above 99.5% can keep about 300 h using 80 g/40 g acid-washed ZVI/ZVAl when treating wastewater containing each heavy metal ions (Cr(VI), Cd{sup 2+}, Ni{sup 2+}, Cu{sup 2+}, and Zn{sup 2+}) concentration of 20.0 mg/L. Scanning electron microscopy (SEM), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS) were used to characterize ZVI/ZVAl before and after reaction and the reaction mechanism of the heavy metal ions with ZVI/ZVAl was discussed.

  9. Studies on the optimum conditions using acid-washed zero-valent iron/aluminum mixtures in permeable reactive barriers for the removal of different heavy metal ions from wastewater

    International Nuclear Information System (INIS)

    Han, Weijiang; Fu, Fenglian; Cheng, Zihang; Tang, Bing; Wu, Shijiao

    2016-01-01

    Highlights: • Acid-washed zero-valent iron and zero-valent aluminum were used in PRBs. • The time that removal efficiencies of heavy metal were above 99.5% can keep 300 h. • Removal mechanism of Cr(VI), Cd 2+ , Ni 2+ , Cu 2+ , and Zn 2+ was discussed. • Heavy metal ions were removed by reduction, adsorption, and co-precipitation. - Abstract: The method of permeable reactive barriers (PRBs) is considered as one of the most practicable approaches in treating heavy metals contaminated surface and groundwater. The mixture of acid-washed zero-valent iron (ZVI) and zero-valent aluminum (ZVAl) as reactive medium in PRBs to treat heavy metal wastewater containing Cr(VI), Cd 2+ , Ni 2+ , Cu 2+ , and Zn 2+ was investigated. The performance of column filled with the mixture of acid-washed ZVI and ZVAl was much better than the column filled with ZVI or ZVAl alone. At initial pH 5.4 and flow rates of 1.0 mL/min, the time that the removal efficiencies of Cr(VI), Cd 2+ , Ni 2+ , Cu 2+ , and Zn 2+ were all above 99.5% can keep about 300 h using 80 g/40 g acid-washed ZVI/ZVAl when treating wastewater containing each heavy metal ions (Cr(VI), Cd 2+ , Ni 2+ , Cu 2+ , and Zn 2+ ) concentration of 20.0 mg/L. Scanning electron microscopy (SEM), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS) were used to characterize ZVI/ZVAl before and after reaction and the reaction mechanism of the heavy metal ions with ZVI/ZVAl was discussed.

  10. Long-term performance of elemental iron and hydroxyapatite for uranium retention in permeable reactive barriers used for groundwater remediation; Langzeitverhalten von elementarem Eisen und Hydroxylapatit zur Uranrueckhaltung in permeablen reaktiven Waenden bei der Grundwassersanierung

    Energy Technology Data Exchange (ETDEWEB)

    Biermann, V.

    2007-11-21

    Elemental iron (Fe{sup 0}) and hydroxyapatite (HAP) were evaluated as reactive mate-rials for use in permeable reactive barriers (PRBs) to remove uranium from conta-minated groundwater. Special attention was given to the long-term performance of the materials, which was investigated by means of column tests with a duration of up to 30 months using two different artificial groundwaters (AGW) with varying composition and uranium concentration. The interaction of the materials with AGW was studied in column tests using {sup 237}U as a radiotracer to monitor the movement of the contamination front through the columns. The tested materials were shredded cast iron (granulated grey cast iron, 0.3 - 1.3 mm) supplied by Gotthard Mayer, Rheinfelden, Germany, and food quality grade hydroxyapatite (Ca{sub 5}(PO{sub 4}){sub 3}OH, 99 % < 0.42 mm) supplied by Che-mische Fabrik Budenheim CFB, Germany. Both materials exhibited uranium retention of more than 99.9% and sorption capacities of up to 28.3 mg U/g HAP and more than 38.4 mg U/g Fe{sup 0} (AGW with 9.6 mg U/L and low bicarbonate content of 120 mg/L). No breakthrough was observed for the Fe{sup 0} columns with effluent uranium con-centrations being below the detection limit of 10 {mu}g/L after treating more than 2,000 pore volumes (PV) and no uranium could be leached from loaded Fe{sup 0} columns with 200 PV of uranium free AGW. However, columns with high Fe{sup 0} content ({>=} 50%) suffered from severe loss of permeability when AGW with {>=} 320 mg/L bicarbonate was used. In the HAP columns a breakthrough occurred with effluent uranium concentrations > 15 {mu}g/l after treating 1,240 PV (10% and 50% breakthrough after 1,460 PV and 2,140 PV respectively). 12.2% of the accu-mulated uranium could be desorbed again with 840 PV of uranium free AGW. Adsorption was found to be the dominant reaction mechanism for uranium and HAP. Image analysis of high uranium content samples showed uranium and phosphate bearing crystals growing

  11. Film Permeability Determination Using Static Permeability Cells

    Science.gov (United States)

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

  12. 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.

  13. Evaluation of permeability of compacted bentonite ground considering heterogeneity by geostatistics

    International Nuclear Information System (INIS)

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

    2007-01-01

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

  14. Development in NMR spiral imaging and application to the assessment of the permeability of the blood-brain barrier on 2 models of brain tumors; Developpements en imagerie RMN spirale et application a la caracterisation de la permeabilite de la barriere hemato-encephalique sur deux modeles de tumeurs intracerebrales

    Energy Technology Data Exchange (ETDEWEB)

    Beaumont, M

    2007-12-15

    The results presented in this work were obtained as part of methodological developments in magnetic resonance imaging. First of all, the setting of the rapid imaging technique using a k-space sampling scheme along a variable density spiral is described. Numerical simulations were used to optimize the acquisitions parameters and to compare different reconstruction techniques. An original approach to calibrate the k-space trajectory was proposed. Then, spiral imaging was used to implement a method to measure the blood brain barrier permeability to Gd-DOTA. This protocol was combined to blood volume and vessel size index measurements using Sinerem. The results obtained highlighted differences between the microvascular parameters measured on C6 and RG2 tumor models. The presence of Sinerem induces a mean decrease of the transfer constant across the vascular wall (Ktrans), in the tumor, of 24 per cent. This study also showed extravasation of the Sinerem, during the first two hours after the product injection, only in the RG2 tumors. (author)

  15. Immune responses at brain barriers and implications for brain development and neurological function in later life

    Directory of Open Access Journals (Sweden)

    Helen B. Stolp

    2013-08-01

    Full Text Available For a long time the brain has been considered an immune-privileged site due to a muted inflammatory response and the presence of protective brain barriers. It is now recognised that neuroinflammation may play an important role in almost all neurological disorders and that the brain barriers may be contributing through either normal immune signalling, or disruption of their basic physiological mechanisms. The distinction between normal function and dysfunction at the barriers is difficult to dissect, partly due to a lack of understanding of normal barrier function and partly because of physiological changes that occur as part of normal development and ageing. Brain barriers consist of a number of interacting structural and physiological elements including tight junctions between adjacent barrier cells and an array of influx and efflux transporters. Despite these protective mechanisms, the capacity for immune-surveillance of the brain is maintained, and there is evidence of inflammatory signalling at the brain barriers that may be an important part of the body’s response to damage or infection. This signalling system appears to change both with normal ageing, and during disease. Changes may affect diapedesis of immune cells and active molecular transfer, or cause rearrangement of the tight junctions and an increase in passive permeability across barrier interfaces. Here we review the many elements that contribute to brain barrier functions and how they respond to inflammation, particularly during development and aging. The implications of inflammation–induced barrier dysfunction for brain development and subsequent neurological function are also discussed.

  16. Active intestinal drug absorption and the solubility-permeability interplay.

    Science.gov (United States)

    Porat, Daniel; Dahan, Arik

    2018-02-15

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

  17. Passive Education

    Science.gov (United States)

    Bojesen, Emile

    2018-01-01

    This paper does not present an advocacy of a passive education as opposed to an active education nor does it propose that passive education is in any way 'better' or more important than active education. Through readings of Maurice Blanchot, Jacques Derrida and B.S. Johnson, and gentle critiques of Jacques Rancière and John Dewey, passive…

  18. Furoxans (oxadiazole-4N-oxides) with Attenuated Reactivity are Neuroprotective, Cross the Blood Brain Barrier, and Improve Passive Avoidance Memory.

    Science.gov (United States)

    Horton, Austin; Nash, Kevin; Tackie-Yarboi, Ethel; Kostrevski, Alexander; Novak, Adam; Raghavan, Aparna; Tulsulkar, Jatin; Alhadidi, Qasim; Wamer, Nathan; Langenderfer, Bryn; Royster, Kalee; Ducharme, Maxwell; Hagood, Katelyn; Post, Megan; Shah, Zahoor A; Schiefer, Isaac T

    2018-04-23

    Nitric oxide (NO) mimetics and other agents capable of enhancing NO/cGMP signaling have demonstrated efficacy as potential therapies for Alzheimer's disease. A group of thiol-dependent NO mimetics known as furoxans may be designed to exhibit attenuated reactivity to provide slow onset NO effects. The present study describes the design, synthesis, and evaluation of a furoxan library resulting in the identification of a prototype furoxan, 5a, which was profiled for use in the CNS. 5a demonstrated negligible reactivity toward generic cellular thiols under physiological conditions. Nonetheless, cGMP dependent neuroprotection was observed. 5a (20 mg/kg) reversed cholinergic memory deficits in a mouse model of passive avoidance fear memory. Importantly, 5a can be prepared as a pharmaceutically acceptable salt and is observed in the brain 12 hr after oral administration, suggesting potential for daily dosing and excellent metabolic stability. Continued investigation into furoxans as attenuated NO mimetics for the CNS is warranted.

  19. An HPLC-UV method for the measurement of permeability of marker drugs in the Caco-2 cell assay

    Directory of Open Access Journals (Sweden)

    J.M. Kratz

    2011-06-01

    Full Text Available The Caco-2 cell line has been used as a model to predict the in vitro permeability of the human intestinal barrier. The predictive potential of the assay relies on an appropriate in-house validation of the method. The objective of the present study was to develop a single HPLC-UV method for the identification and quantitation of marker drugs and to determine the suitability of the Caco-2 cell permeability assay. A simple chromatographic method was developed for the simultaneous determination of both passively (propranolol, carbamazepine, acyclovir, and hydrochlorothiazide and actively transported drugs (vinblastine and verapamil. Separation was achieved on a C18 column with step-gradient elution (acetonitrile and aqueous solution of ammonium acetate, pH 3.0 at a flow rate of 1.0 mL/min and UV detection at 275 nm during the total run time of 35 min. The method was validated and found to be specific, linear, precise, and accurate. This chromatographic system can be readily used on a routine basis and its utilization can be extended to other permeability models. The results obtained in the Caco-2 bi-directional transport experiments confirmed the validity of the assay, given that high and low permeability profiles were identified, and P-glycoprotein functionality was established.

  20. Permeability prediction in chalks

    DEFF Research Database (Denmark)

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

    2011-01-01

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

  1. A Triple Culture Model of the Blood-Brain Barrier Using Porcine Brain Endothelial cells, Astrocytes and Pericytes.

    Science.gov (United States)

    Thomsen, Louiza Bohn; Burkhart, Annette; Moos, Torben

    2015-01-01

    In vitro blood-brain barrier (BBB) models based on primary brain endothelial cells (BECs) cultured as monoculture or in co-culture with primary astrocytes and pericytes are useful for studying many properties of the BBB. The BECs retain their expression of tight junction proteins and efflux transporters leading to high trans-endothelial electric resistance (TEER) and low passive paracellular permeability. The BECs, astrocytes and pericytes are often isolated from small rodents. Larger species as cows and pigs however, reveal a higher yield, are readily available and have a closer resemblance to humans, which make them favorable high-throughput sources for cellular isolation. The aim of the present study has been to determine if the preferable combination of purely porcine cells isolated from the 6 months old domestic pigs, i.e. porcine brain endothelial cells (PBECs) in co-culture with porcine astrocytes and pericytes, would compare with PBECs co-cultured with astrocytes and pericytes isolated from newborn rats with respect to TEER value and low passive permeability. The astrocytes and pericytes were grown both as contact and non-contact co-cultures as well as in triple culture to examine their effects on the PBECs for barrier formation as revealed by TEER, passive permeability, and expression patterns of tight junction proteins, efflux transporters and the transferrin receptor. This syngenic porcine in vitro BBB model is comparable to triple cultures using PBECs, rat astrocytes and rat pericytes with respect to TEER formation, low passive permeability, and expression of hallmark proteins signifying the brain endothelium (tight junction proteins claudin 5 and occludin, the efflux transporters P-glycoprotein (PgP) and breast cancer related protein (BCRP), and the transferrin receptor).

  2. A Triple Culture Model of the Blood-Brain Barrier Using Porcine Brain Endothelial cells, Astrocytes and Pericytes.

    Directory of Open Access Journals (Sweden)

    Louiza Bohn Thomsen

    Full Text Available In vitro blood-brain barrier (BBB models based on primary brain endothelial cells (BECs cultured as monoculture or in co-culture with primary astrocytes and pericytes are useful for studying many properties of the BBB. The BECs retain their expression of tight junction proteins and efflux transporters leading to high trans-endothelial electric resistance (TEER and low passive paracellular permeability. The BECs, astrocytes and pericytes are often isolated from small rodents. Larger species as cows and pigs however, reveal a higher yield, are readily available and have a closer resemblance to humans, which make them favorable high-throughput sources for cellular isolation. The aim of the present study has been to determine if the preferable combination of purely porcine cells isolated from the 6 months old domestic pigs, i.e. porcine brain endothelial cells (PBECs in co-culture with porcine astrocytes and pericytes, would compare with PBECs co-cultured with astrocytes and pericytes isolated from newborn rats with respect to TEER value and low passive permeability. The astrocytes and pericytes were grown both as contact and non-contact co-cultures as well as in triple culture to examine their effects on the PBECs for barrier formation as revealed by TEER, passive permeability, and expression patterns of tight junction proteins, efflux transporters and the transferrin receptor. This syngenic porcine in vitro BBB model is comparable to triple cultures using PBECs, rat astrocytes and rat pericytes with respect to TEER formation, low passive permeability, and expression of hallmark proteins signifying the brain endothelium (tight junction proteins claudin 5 and occludin, the efflux transporters P-glycoprotein (PgP and breast cancer related protein (BCRP, and the transferrin receptor.

  3. Long term performance of the Waterloo denitrification barrier

    International Nuclear Information System (INIS)

    Robertson, W.D.; Cherry, J.A.

    1997-01-01

    Beginning in 1991 a series of laboratory tests and small scale field trials were initiated to test the performance of an innovative permeable reactive barrier for treatment of nitrate from septic systems. The barrier promotes denitrification by providing an energy source in the form of solid organic carbon mixed into the porous media material. Advantages of the system for nitrate treatment are that the reaction is passive and in situ and it is possible to incorporate sufficient carbon mass in conveniently sized barriers to potentially provide treatment for long periods (decades) without the necessity for maintenance. However, longevity can only be demonstrated by careful long term monitoring of field installations. This paper documents four years of operating history at three small scale field trials; two where the denitrification barrier is installed as a horizontal layer positioned in the unsaturated zone below conventional septic system infiltration beds and one where the barrier is installed as a vertical wall intercepting a septic system plume at a downgradient location. The barriers have successfully attenuated 50-100% of NO - 3 -N levels of up to 170 mg/L and treatment has remained consistent over the four year period in each case, thus considerable longevity is indicated. Other field trials have demonstrated this technology to be equally effective in treating nitrogen contamination from other sources such as landfill leachate and farm field runoff

  4. 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....

  5. [Blood-brain barrier part III: therapeutic approaches to cross the blood-brain barrier and target the brain].

    Science.gov (United States)

    Weiss, N; Miller, F; Cazaubon, S; Couraud, P-O

    2010-03-01

    Over the last few years, the blood-brain barrier has come to be considered as the main limitation for the treatment of neurological diseases caused by inflammatory, tumor or neurodegenerative disorders. In the blood-brain barrier, the close intercellular contact between cerebral endothelial cells due to tight junctions prevents the passive diffusion of hydrophilic components from the bloodstream into the brain. Several specific transport systems (via transporters expressed on cerebral endothelial cells) are implicated in the delivery of nutriments, ions and vitamins to the brain; other transporters expressed on cerebral endothelial cells extrude endogenous substances or xenobiotics, which have crossed the cerebral endothelium, out of the brain and into the bloodstream. Recently, several strategies have been proposed to target the brain, (i) by by-passing the blood-brain barrier by central drug administration, (ii) by increasing permeability of the blood-brain barrier, (iii) by modulating the expression and/or the activity of efflux transporters, (iv) by using the physiological receptor-dependent blood-brain barrier transport, and (v) by creating new viral or chemical vectors to cross the blood-brain barrier. This review focuses on the illustration of these different approaches. Copyright (c) 2009 Elsevier Masson SAS. All rights reserved.

  6. Rehabilitation of a house with high radon level, using a ground ventilation system with double barrier

    International Nuclear Information System (INIS)

    Bonnefous, Y.C.; Richon, P.; Arnautou, J.C.; Sabroux, J.C.

    1995-01-01

    A ground ventilation system has been designed and implemented in a town hall in Brittany. Radon concentration in the heating unit room of this building has been reduced from 10000 Bq/m 3 to less than 200 Bq/m 3 by the means of a depressurization system using a 32 W fan, which blows air into a permeable gravel layer intercalated between two radon barrier mylar films. Results show that passive systems should be applicable; for new buildings, very low energy consumption systems with 10 W fans, are easily implemented if designed before construction

  7. Permeability of porour rhyolite

    Science.gov (United States)

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

    2003-04-01

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

  8. Soils - Mean Permeability

    Data.gov (United States)

    Kansas Data Access and Support Center — This digital spatial data set provides information on the magnitude and spatial pattern of depth-weighted, mean soil permeability throughout the State of Kansas. The...

  9. 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

  10. Permeable pavement study (Edison)

    Data.gov (United States)

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

  11. Intestinal Permeability: The Basics

    Directory of Open Access Journals (Sweden)

    Ingvar Bjarnason

    1995-01-01

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

  12. Passive Methods as a Solution for Improving Indoor Environments

    CERN Document Server

    Orosa, José A

    2012-01-01

    There are many aspects to consider when evaluating or improving an indoor environment; thermal comfort, energy saving, preservation of materials, hygiene and health are all key aspects which can be improved by passive methods of environmental control. Passive Methods as a Solution for Improving Indoor Environments endeavours to fill the lack of analysis in this area by using over ten years of research to illustrate the effects of methods such as thermal inertia and permeable coverings; for example, the use of permeable coverings is a well known passive method, but its effects and ways to improve indoor environments have been rarely analyzed.   Passive Methods as a Solution for Improving Indoor Environments  includes both software simulations and laboratory and field studies. Through these, the main parameters that characterize the behavior of internal coverings are defined. Furthermore, a new procedure is explained in depth which can be used to identify the real expected effects of permeable coverings such ...

  13. Biostable glucose permeable polymer

    DEFF Research Database (Denmark)

    2017-01-01

    A new biostable glucose permeable polymer has been developed which is useful, for example, in implantable glucose sensors. This biostable glucose permeable polymer has a number of advantageous characteristics and, for example, does not undergo hydrolytic cleavage and degradation, thereby providing...... a composition that facilitates long term sensor stability in vivo. The versatile characteristics of this polymer allow it to be used in a variety of contexts, for example to form the body of an implantable glucose sensor. The invention includes the polymer composition, sensor systems formed from this polymer...

  14. Urea uptake enhances barrier function and antimicrobial defense in humans by regulating epidermal gene expression

    Science.gov (United States)

    Grether-Beck, Susanne; Felsner, Ingo; Brenden, Heidi; Kohne, Zippora; Majora, Marc; Marini, Alessandra; Jaenicke, Thomas; Rodriguez-Martin, Marina; Trullas, Carles; Hupe, Melanie; Elias, Peter M.; Krutmann, Jean

    2012-01-01

    Urea is an endogenous metabolite, known to enhance stratum corneum hydration. Yet, topical urea anecdotally also improves permeability barrier function, and it appears to exhibit antimicrobial activity. Hence, we hypothesized that urea is not merely a passive metabolite, but a small-molecule regulator of epidermal structure and function. In 21 human volunteers, topical urea improved barrier function in parallel with enhanced antimicrobial peptide (LL-37 and β-defensin-2) expression. Urea both stimulates expression of, and is transported into keratinocytes by two urea transporters, UT-A1 and UT-A2, and by aquaporin 3, 7 and 9. Inhibitors of these urea transporters block the downstream biological effects of urea, which include increased mRNA and protein levels for: (i) transglutaminase-1, involucrin, loricrin and filaggrin; (ii) epidermal lipid synthetic enzymes, and (iii) cathelicidin/LL-37 and β-defensin-2. Finally, we explored the potential clinical utility of urea, showing that topical urea applications normalized both barrier function and antimicrobial peptide expression in a murine model of atopic dermatitis (AD). Together, these results show that urea is a small-molecule regulator of epidermal permeability barrier function and antimicrobial peptide expression after transporter uptake, followed by gene regulatory activity in normal epidermis, with potential therapeutic applications in diseased skin. PMID:22418868

  15. Endothelial cell permeability to water and antipyrine

    International Nuclear Information System (INIS)

    Garrick, R.A.

    1986-01-01

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

  16. Passive water and ion transport by cotransporters

    DEFF Research Database (Denmark)

    Loo, D D; Hirayama, B A; Meinild, A K

    1999-01-01

    the Lp of control oocytes. Passive Na+ transport (Na+ leak) was obtained from the blocker-sensitive Na+ currents in the absence of substrates (glucose and GABA). 2. Passive Na+ and water transport through SGLT1 were blocked by phlorizin with the same sensitivity (inhibitory constant (Ki), 3-5 micro......1. The rabbit Na+-glucose (SGLT1) and the human Na+-Cl--GABA (GAT1) cotransporters were expressed in Xenopus laevis oocytes, and passive Na+ and water transport were studied using electrical and optical techniques. Passive water permeabilities (Lp) of the cotransporters were determined from......M). When Na+ was replaced with Li+, phlorizin also inhibited Li+ and water transport, but with a lower affinity (Ki, 100 microM). When Na+ was replaced by choline, which is not transported, the SGLT1 Lp was indistinguishable from that in Na+ or Li+, but in this case water transport was less sensitive...

  17. GAS PERMEABILITY OF GEOSYNTHETIC CLAY LINERS

    Directory of Open Access Journals (Sweden)

    Helena Vučenović

    2017-01-01

    Full Text Available Geosynthetic clay liners (GCL are manufactured hydraulic barriers consisting of mineral and geosynthetic components. They belong to a group of geosynthetic products whose primary purpose is to seal and they have been used in many geotechnical and hydrotechnical applications, landfi lls and liquid waste lagoons for quite a while. They are used in landfill final cover systems to prevent the infi ltration of precipitation into the landfi ll body and the penetration of gases and liquids from the landfill into the atmosphere and environment. Laboratory and fi eld research and observations on regulated landfi lls have proven the eff ectiveness of GCL as a barrier for the infi ltration of precipitation into the landfi ll body as well as the drainage of fl uid beneath the landfill. Due to the presence of high concentrations of gases in the landfill body, there is a growing interest in determining the efficiency of GCL as a gas barrier. It was not until the last twenty years that the importance of this topic was recognized. In this article, current GCL gas permeability studies, the testing methods and test results of gas permeability in laboratory conditions are described.

  18. Comparative study of four immortalized human brain capillary endothelial cell lines, hCMEC/D3, hBMEC, TY10, and BB19, and optimization of culture conditions, for an in vitro blood-brain barrier model for drug permeability studies.

    Science.gov (United States)

    Eigenmann, Daniela E; Xue, Gongda; Kim, Kwang S; Moses, Ashlee V; Hamburger, Matthias; Oufir, Mouhssin

    2013-11-22

    Reliable human in vitro blood-brain barrier (BBB) models suitable for high-throughput screening are urgently needed in early drug discovery and development for assessing the ability of promising bioactive compounds to overcome the BBB. To establish an improved human in vitro BBB model, we compared four currently available and well characterized immortalized human brain capillary endothelial cell lines, hCMEC/D3, hBMEC, TY10, and BB19, with respect to barrier tightness and paracellular permeability. Co-culture systems using immortalized human astrocytes (SVG-A cell line) and immortalized human pericytes (HBPCT cell line) were designed with the aim of positively influencing barrier tightness. Tight junction (TJ) formation was assessed by transendothelial electrical resistance (TEER) measurements using a conventional epithelial voltohmmeter (EVOM) and an automated CellZscope system which records TEER and cell layer capacitance (CCL) in real-time.Paracellular permeability was assessed using two fluorescent marker compounds with low BBB penetration (sodium fluorescein (Na-F) and lucifer yellow (LY)). Conditions were optimized for each endothelial cell line by screening a series of 24-well tissue culture inserts from different providers. For hBMEC cells, further optimization was carried out by varying coating material, coating procedure, cell seeding density, and growth media composition. Biochemical characterization of cell type-specific transmembrane adherens junction protein VE-cadherin and of TJ proteins ZO-1 and claudin-5 were carried out for each endothelial cell line. In addition, immunostaining for ZO-1 in hBMEC cell line was performed. The four cell lines all expressed the endothelial cell type-specific adherens junction protein VE-cadherin. The TJ protein ZO-1 was expressed in hCMEC/D3 and in hBMEC cells. ZO-1 expression could be confirmed in hBMEC cells by immunocytochemical staining. Claudin-5 expression was detected in hCMEC/D3, TY10, and at a very low level

  19. The Use of Waste Materials in the Passive Remediation of Mine Water Polution

    Science.gov (United States)

    Batty, Lesley C.; Younger, Paul L.

    2004-01-01

    The contamination and resulting degradation of water courses by effluents from abandoned and active mines is a world-wide problem. Traditional methods of remediating the discharges from mines involve the addition of chemicals and the utilisation of artificial energy sources. Over the last 15-20 years passive treatment systems have been developed that harness natural chemical and biological processes to ameliorate the potentially toxic effects of such discharges. There are many different types of passive system, including compost wetlands, reducing and alkalinity producing systems (RAPS), permeable reactive barriers and inorganic media passive systems. Different waste materials can be utilised as reactive media within each of these systems, dependent upon the type of mine water and treatment technology. In many cases the reactivity of these recycled waste materials is key to the remedial performance of these systems. The materials used may be organic (e.g., composts) or inorganic (e.g., blast furnace slag) and where possible are sourced locally in order to minimise transport costs. The remediation of mine waters in itself can produce large quantities of waste products in the form of iron oxide sludge. Potential uses of this material in the production of pigments and in the treatment of phosphate contaminated waters is also currently under investigation. The exploitation of what are traditionally thought of as waste materials within treatment systems for polluted waters is an expanding technology which provides great scope for recycling.

  20. Compositional properties of passivity

    NARCIS (Netherlands)

    Kerber, Florian; van der Schaft, Arjan

    2011-01-01

    The classical passivity theorem states that the negative feedback interconnection of passive systems is again passive. The converse statement, - passivity of the interconnected system implies passivity of the subsystems -, turns out to be equally valid. This result implies that among all feasible

  1. Development of a passive sampler based on a polymer inclusion membrane for total ammonia monitoring in freshwaters.

    Science.gov (United States)

    Almeida, M Inês G S; Silva, Adélia M L; Coleman, Rhys A; Pettigrove, Vincent J; Cattrall, Robert W; Kolev, Spas D

    2016-05-01

    A passive sampler for determining the time-weighted average total ammonia (i.e. molecular ammonia and the ammonium cation) concentration (C TWA) in freshwaters, which incorporated a polymer inclusion membrane (PIM) as a semi-permeable barrier separating the aqueous source solution from the receiving solution (i.e. 0.8 mol L(-1) HCl), was developed for the first time. The PIM was composed of dinonylnaphthalene sulfonic acid (DNNS) as a carrier, poly (vinyl chloride) (PVC) as a base polymer and 1-tetradecanol as a modifier. Its optimal composition was found to be 35 wt% commercial DNNS, 55 wt% PVC and 10 wt% 1-tetradecanol. The effect of environmental variables such as the water matrix, pH and temperature were also studied using synthetic freshwaters. The passive sampler was calibrated under laboratory conditions using synthetic freshwaters and exhibited a linear response within the concentration range 0.59-2.8 mg L(-1) NH4(+) (0.46-2.1 mg N L(-1)) at 20 °C. The performance of the sampler was further investigated under field conditions over 7 days. A strong correlation between spot sampling and passive sampling was achieved, thus providing a proof-of-concept for the passive sampler for reliably measuring the C(TWA) of total ammonia in freshwaters, which can be used as an indicator in tracking sources of faecal contamination in stormwater drains.

  2. Intestinal permeability - a new target for disease prevention and therapy

    NARCIS (Netherlands)

    Bischoff, S.C.; Barbara, G.; Buurman, W.; Ockhuizen, T.; Schulzke, J.D.; Serino, M.; Tilg, H.; Watson, A.; Wells, J.M.

    2014-01-01

    Data are accumulating that emphasize the important role of the intestinal barrier and intestinal permeability for health and disease. However, these terms are poorly defined, their assessment is a matter of debate, and their clinical significance is not clearly established. In the present review,

  3. Geophysical characterization of subsurface barriers

    International Nuclear Information System (INIS)

    Borns, D.J.

    1995-08-01

    An option for controlling contaminant migration from plumes and buried waste sites is to construct a subsurface barrier of a low-permeability material. The successful application of subsurface barriers requires processes to verify the emplacement and effectiveness of barrier and to monitor the performance of a barrier after emplacement. Non destructive and remote sensing techniques, such as geophysical methods, are possible technologies to address these needs. The changes in mechanical, hydrologic and chemical properties associated with the emplacement of an engineered barrier will affect geophysical properties such a seismic velocity, electrical conductivity, and dielectric constant. Also, the barrier, once emplaced and interacting with the in situ geologic system, may affect the paths along which electrical current flows in the subsurface. These changes in properties and processes facilitate the detection and monitoring of the barrier. The approaches to characterizing and monitoring engineered barriers can be divided between (1) methods that directly image the barrier using the contrasts in physical properties between the barrier and the host soil or rock and (2) methods that reflect flow processes around or through the barrier. For example, seismic methods that delineate the changes in density and stiffness associated with the barrier represents a direct imaging method. Electrical self potential methods and flow probes based on heat flow methods represent techniques that can delineate the flow path or flow processes around and through a barrier

  4. Permeability measuremens of brazilian Eucalyptus

    Directory of Open Access Journals (Sweden)

    Marcio Rogério da Silva

    2010-09-01

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

  5. Permeability of dura mater

    DEFF Research Database (Denmark)

    Tfelt-Hansen, Peer Carsten

    2011-01-01

    In the wake of cortical spreading depression (CSD) it has been suggested that noxious substances diffuse through the dura with resulting firing of epidural nerves. In my view this is unlikely because there are good reasons to suggest that there must be a dura-brain barrier. Alternatively collateral...

  6. Passive solar technology

    Energy Technology Data Exchange (ETDEWEB)

    Watson, D

    1981-04-01

    The present status of passive solar technology is summarized, including passive solar heating, cooling and daylighting. The key roles of the passive solar system designer and of innovation in the building industry are described. After definitions of passive design and a summary of passive design principles are given, performance and costs of passive solar technology are discussed. Passive energy design concepts or methods are then considered in the context of the overall process by which building decisions are made to achieve the integration of new techniques into conventional design. (LEW).

  7. Phonic Attenuation due to Screen-Barriers

    Directory of Open Access Journals (Sweden)

    Vasile Bacria

    2011-10-01

    Full Text Available The technique of noise decreasing admits two basic approaches: an active approach and a passive one. In the frame of passive method one can count the employment of screen-barriers. In this paper we present some considerations on sound attenuation due to screen-barriers emphasizing the elements which influence it. The elucidation of these elements is made by measurements. The obtained results can be applied in every other practical situation concerning the protection against noise.

  8. Fundamental studies of passivity and passivity breakdown

    International Nuclear Information System (INIS)

    Macdonald, D.D.; Urquidi-Macdonald, M.; Song, H.; Biaggio-Rocha, S.; Searson, P.

    1991-11-01

    This report summarizes the findings of our fundamental research program on passivity and passivity breakdown. During the past three and one half years in this program (including the three year incrementally-funded grant prior to the present grant), we developed and experimentally tested various physical models for the growth and breakdown of passive films on metal surfaces. These models belong to a general class termed ''point defects models'' (PDMs), in which the growth and breakdown of passive films are described in terms of the movement of anion and cation vacancies

  9. Electrokinetic effects and fluid permeability

    International Nuclear Information System (INIS)

    Berryman, J.G.

    2003-01-01

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

  10. Permeability testing of biomaterial membranes

    Energy Technology Data Exchange (ETDEWEB)

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

    2008-09-01

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

  11. Permeability testing of biomaterial membranes

    International Nuclear Information System (INIS)

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

    2008-01-01

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

  12. Relative Permeability of Fractured Rock

    Energy Technology Data Exchange (ETDEWEB)

    Mark D. Habana

    2002-06-30

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

  13. Evaluation of layered and mixed passive treatment systems for acid mine drainage.

    Science.gov (United States)

    Jeen, Sung-Wook; Mattson, Bruce

    2016-11-01

    Laboratory column tests for passive treatment systems for mine drainage from a waste rock storage area were conducted to evaluate suitable reactive mixture, system configuration, effects of influent water chemistry, and required residence time. Five columns containing straw, chicken manure, mushroom compost, and limestone (LS), in either layered or mixed configurations, were set up to simulate the treatment system. The results showed that all of the five columns removed metals of concern (i.e. Al, Cd, Co, Cu, Fe, Ni, and Zn) with a residence time of 15 h and greater. Reaction mechanisms responsible for the removal of metals may include sulfate reduction and subsequent sulfide precipitation, precipitation of secondary carbonates and hydroxides, co-precipitation, and sorption on organic substrates and secondary precipitates. The results suggest that the mixed systems containing organic materials and LS perform better than the layered systems, sequentially treated by organic and LS layers, due to the enhanced pH adjustment, which is beneficial to bacterial activity and precipitation of secondary minerals. The column tests provide a basis for the design of a field-scale passive treatment system, such as a reducing and alkalinity producing system or a permeable reactive barrier.

  14. Immunizations: Active vs. Passive

    Science.gov (United States)

    ... Issues Health Issues Health Issues Conditions Injuries & Emergencies Vaccine Preventable Diseases ... Children > Safety & Prevention > Immunizations > Immunizations: Active vs. Passive Safety & ...

  15. Sensing of Vascular Permeability in Inflamed Vessel of Live Animal

    Directory of Open Access Journals (Sweden)

    Sang A Park

    2018-01-01

    Full Text Available Increase in vascular permeability is a conclusive response in the progress of inflammation. Under controlled conditions, leukocytes are known to migrate across the vascular barriers to the sites of inflammation without severe vascular rupture. However, when inflammatory state becomes excessive, the leakage of blood components may occur and can be lethal. Basically, vascular permeability can be analyzed based on the intensity of blood outflow. To evaluate the amount and rate of leakage in live mice, we performed cremaster muscle exteriorization to visualize blood flow and neutrophil migration. Using two-photon intravital microscopy of the exteriorized cremaster muscle venules, we found that vascular barrier function is transiently and locally disrupted in the early stage of inflammatory condition induced by N-formylmethionyl-leucyl-phenylalanine (fMLP. Measurement of the concentration of intravenously (i.v. injected Texas Red dextran inside and outside the vessels resulted in clear visualization of real-time increases in transient and local vascular permeability increase in real-time manner. We successfully demonstrated repeated leakage from a target site on a blood vessel in association with increasing severity of inflammation. Therefore, compared to other methods, two-photon intravital microscopy more accurately visualizes and quantifies vascular permeability even in a small part of blood vessels in live animals in real time.

  16. Biliary obstruction dissipates bioelectric sinusoidal-canalicular barrier without altering taurocholate uptake

    International Nuclear Information System (INIS)

    Cotting, J.; Zysset, T.; Reichen, J.

    1989-01-01

    To study immediate events during extrahepatic cholestasis, we investigated the effect of short-term biliary obstruction on the bioelectrical sinusoidal-canalicular barrier in the rat using molecular weight-matched uncharged and negatively charged inert solute pairs. The bioelectrical barrier averaged -22 +/- 5 and -18 +/- 4 mV (NS) using the pair carboxy-/methoxyinulin and ferrocyanide/sucrose, respectively. After a 20-min biliary obstruction both decreased by 61 and 11%, respectively, but only the large molecular weight pair (the inulins) returned to base line after release of the obstruction. Inert solute clearances were increased after short biliary obstruction depending on molecular size and negative charge (ferrocyanide greater than sucrose greater than carboxyinulin greater than inulin), suggesting that both permeability and bioelectrical barriers were affected by obstruction. The hepatic extraction in vivo of a passively transported drug not excreted into bile (D-propranolol) was not affected by obstruction, whereas that of an actively transported drug (glycocholate) decreased from 66 +/- 8 to 41 +/- 20% during biliary obstruction (P less than 0.01). Unidirectional transfer of glycocholate was not affected by short-term biliary obstruction in the situ perfused rat liver; however, 2 min after [14C]glycocholate administration, increased return was observed in hepatic venous effluent in obstructed animals. Our findings demonstrate a loss of the bioelectrical barrier immediately after short-term biliary obstruction. Decreased hepatic extraction in the view of unaltered sinusoidal uptake demonstrates regurgitation of bile into blood during short-term biliary obstruction

  17. Hydrogenation of passivated contacts

    Energy Technology Data Exchange (ETDEWEB)

    Nemeth, William; Yuan, Hao-Chih; LaSalvia, Vincenzo; Stradins, Pauls; Page, Matthew R.

    2018-03-06

    Methods of hydrogenation of passivated contacts using materials having hydrogen impurities are provided. An example method includes applying, to a passivated contact, a layer of a material, the material containing hydrogen impurities. The method further includes subsequently annealing the material and subsequently removing the material from the passivated contact.

  18. Geothermal Permeability Enhancement - Final Report

    Energy Technology Data Exchange (ETDEWEB)

    Joe Beall; Mark Walters

    2009-06-30

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

  19. Treatment for cracked and permeable Houston clay

    International Nuclear Information System (INIS)

    Vipulanandan, C.; Leung, M.

    1991-01-01

    In this study, the treatability of a field clay (obtained from Houston, Texas) and a clay-sand mixture to reduce their hydraulic conductivity was evaluated. Remolded field clay and clay-sand mixture with and without methanol contamination were treated to reduce their hydraulic conductivity by permeating very dilute grout solutions. The concentration of sodium silicate in the grout solution was 8%, while the solid content in the cement grout was 0.3%. The hydraulic conductivity of permeable Houston clay (hydraulic conductivity >10 -5 cm/sec) could be reduced to less than 10 -7 cm/sec (U.S. EPA limit for soil barriers) by permeating with a selected combination of grout solutions

  20. Permeable Reactive Barriers: Lessons Learned/New Directions

    Science.gov (United States)

    2005-02-01

    various • compost (various compositions), and • pecan she 2.2 Tre The basic objective of any PRB-treatment material is to either directly destroy or...barrier” of pecan shells and cottonseed admixed with gravel (to deplete dissolved oxygen, and destroy any Resource Conservation and Recovery Act [RCRA...Zone 2 San Antonio, TX, USA BP continuous wall Nov 04 Industrial facility Italy BP continuous wall Nov 04 Industrial facility Ohio, USA Continuous

  1. Field Applications of In Situ Remediation Technologies: Permeable Reactive Barriers

    Science.gov (United States)

    2002-01-01

    enter PRB; level of Fax: 43-2243-22843 contamination Email: niederbacher@geol.at varies with groundwater level Marzone Inc./ Tifton , GA 1998 BHC, beta...system should be constructed to allow for gas venting (Bodo Canyon, Marzone). � The length of trench box should be mini- mized to reduce slope failure

  2. Performance Monitoring of the Permeable Reactive Barrier at Dover AFB

    National Research Council Canada - National Science Library

    1999-01-01

    Based on column tests conducted between February and June 1997, NERL recommended that in terms of effectiveness in achieving cleanup standards and kinetics, a pyrite-iron combination ranked as the best reactive medium (EPA, 1997...

  3. Permeability of cork to gases.

    Science.gov (United States)

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

    2011-04-27

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

  4. Identifiability of location and magnitude of flow barriers in slightly compressible flow

    NARCIS (Netherlands)

    Kahrobaei, S.; Mansoori Habib Abadi, M.; Joosten, G.J.P.; Hof, Van den P.M.J.; Jansen, J.D.

    2015-01-01

    Classic identifiability analysis of flow barriers in incompressible single-phase flow reveals that it is not possible to identify the location and permeability of low-permeability barriers from production data (wellbore pressures and rates), and that only averaged reservoir properties in between

  5. Identifiability of location and magnitude of flow barriers in slightly compressible flow

    NARCIS (Netherlands)

    Kahrobaei, S.; Mansoori Habib Abadi, M.; Joosten, G.J.P.; Van den Hof, P.; Jansen, J.D.

    2016-01-01

    Classic identifiability analysis of flow barriers in incompressible single-phase flow reveals that it is not possible to identify the location and permeability of low-permeability barriers from production data (wellbore pressures and rates), and that only averaged reservoir properties in between

  6. Bentonite Permeability at Elevated Temperature

    Directory of Open Access Journals (Sweden)

    Katherine A. Daniels

    2017-01-01

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

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

    Science.gov (United States)

    Volpe, Donna A

    2011-12-01

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

  8. Permeability enhancement by shock cooling

    Science.gov (United States)

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

    2015-04-01

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

  9. A passive sampler for atmospheric ozone

    International Nuclear Information System (INIS)

    Grosjean, D.; Hisham, M.W.M.

    1992-01-01

    A simple, cost-effective passive sampler has been developed for the determination of atmospheric ozone. This passive sampler is based on a colorant which fades upon reaction with ozone, whose concentration can be determined by reflectance measurement of the color change. Direct, on-site measurements are possible, and no chemical analyses are needed. Sampler design and validation studies have been carried out and included quantitative determination of color change vs exposure time (1-8 days), color change vs. ozone concentration (30-350 ppb), and response to changes in sampler configuration that modify the passive sampling rate. With indigo carmine as the colorant, the detection limits are 30 ppb. day and 120 ppb. day using a plastic grid and Teflon filter, respectively, as diffusion barriers. Interferences from nitrogen dioxide, formaldehyde and peroxyacetyl nitrate are 15, 4 and 16%, respectively, thus resulting in a negligible bias when measuring ozone in ambient air

  10. 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)

  11. Gap junction protein connexin43 exacerbates lung vascular permeability.

    Directory of Open Access Journals (Sweden)

    James J O'Donnell

    Full Text Available Increased vascular permeability causes pulmonary edema that impairs arterial oxygenation and thus contributes to morbidity and mortality associated with Acute Respiratory Distress Syndrome and sepsis. Although components of intercellular adhesive and tight junctions are critical for maintaining the endothelial barrier, there has been limited study of the roles of gap junctions and their component proteins (connexins. Since connexins can modulate inflammatory signaling in other systems, we hypothesized that connexins may also regulate pulmonary endothelial permeability. The relationships between connexins and the permeability response to inflammatory stimuli were studied in cultured human pulmonary endothelial cells. Prolonged treatment with thrombin, lipopolysaccharide, or pathological cyclic stretch increased levels of mRNA and protein for the major connexin, connexin43 (Cx43. Thrombin and lipopolysaccharide both increased intercellular communication assayed by transfer of microinjected Lucifer yellow. Although thrombin decreased transendothelial resistance in these cells, the response was attenuated by pretreatment with the connexin inhibitor carbenoxolone. Additionally, the decreases of transendothelial resistance produced by either thrombin or lipopolysaccharide were attenuated by reducing Cx43 expression by siRNA knockdown. Both carbenoxolone and Cx43 knockdown also abrogated thrombin-induced phosphorylation of myosin light chain. Taken together, these data suggest that increased lung vascular permeability induced by inflammatory conditions may be amplified via increased expression of Cx43 and intercellular communication among pulmonary endothelial cells.

  12. Passive magnetic bearing configurations

    Science.gov (United States)

    Post, Richard F [Walnut Creek, CA

    2011-01-25

    A journal bearing provides vertical and radial stability to a rotor of a passive magnetic bearing system when the rotor is not rotating and when it is rotating. In the passive magnetic bearing system, the rotor has a vertical axis of rotation. Without the journal bearing, the rotor is vertically and radially unstable when stationary, and is vertically stable and radially unstable when rotating.

  13. 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.

  14. Passive solar construction handbook

    Energy Technology Data Exchange (ETDEWEB)

    Levy, E.; Evans, D.; Gardstein, C.

    1981-08-01

    Many of the basic elements of passive solar design are reviewed. The unique design constraints presented in passive homes are introduced and many of the salient issues influencing design decisions are described briefly. Passive solar construction is described for each passive system type: direct gain, thermal storage wall, attached sunspace, thermal storage roof, and convective loop. For each system type, important design and construction issues are discussed and case studies illustrating designed and built examples of the system type are presented. Construction details are given and construction and thermal performance information is given for the materials used in collector components, storage components, and control components. Included are glazing materials, framing systems, caulking and sealants, concrete masonry, concrete, brick, shading, reflectors, and insulators. The Load Collector Ratio method for estimating passive system performance is appended, and other analysis methods are briefly summarized. (LEW)

  15. European Embedding of Passive Houses. www.europeanpassivehouses.org

    Energy Technology Data Exchange (ETDEWEB)

    Elswijk, M.; Kaan, H. (eds.) [and others

    2008-05-15

    The passive house concept has become a European wide accepted solution to reach a significant energy demand reduction in the built environment. The European Commission has published the ambition to construct newly built ho uses in 2015 accordingly to the passive ho use standard. In most project participating countries this ambition is shared. With the support of the Intelligent Energy Europe program this project 'Promotion of European Passive Houses' (PEP-project) contributed to achieve this ambition to clear the first market barriers internationally to reach the status 'Business As Usual' for passive houses in 2015. The PEP project aimed at the development of easy accessible web based documentation for stakeholders in the building process to solve national market introduction barriers regarding the passive house concept. The project also aimed at the distribution of this information via international and national workshops, seminars and conferences. It can be concluded that the PEP-project has been successful. All participating countries made significant progress in the societal embedding process of passive houses and in most countries the passive house concept is on the brink of breaking through nationally. Further, the PEP-project contributed successfully in the internationalisation of the Internal Passive House Conference and fixed the definition of a passive house for three geographical European regions. Finally, the PEP website with its wealth of information was a powerful tool for promotion of passive houses in Europe. In order to increase the implementation efficiency of the passive house concept it is recommended to develop additional information packages concerning passive house solutions for offices, schools and social homes (e.g. architectural examples, organisational issues); passive house renovations; financial schemes for passive houses; performance oriented quality approach for the design and construction process; industrial

  16. Dopamine enhances duodenal epithelial permeability via the dopamine D5 receptor in rodent.

    Science.gov (United States)

    Feng, X-Y; Zhang, D-N; Wang, Y-A; Fan, R-F; Hong, F; Zhang, Y; Li, Y; Zhu, J-X

    2017-05-01

    The intestinal barrier is made up of epithelial cells and intercellular junctional complexes to regulate epithelial ion transport and permeability. Dopamine (DA) is able to promote duodenal epithelial ion transport through D1-like receptors, which includes subtypes of D 1 (D 1 R) and D 5 (D 5 R), but whether D1-like receptors influence the duodenal permeability is unclear. FITC-dextran permeability, short-circuit current (I SC ), Western blot, immunohistochemistry and ELISA were used in human D 5 R transgenic mice and hyperendogenous enteric DA (HEnD) rats in this study. Dopamine induced a downward deflection in I SC and an increase in FITC-dextran permeability of control rat duodenum, which were inhibited by the D1-like receptor antagonist, SCH-23390. However, DA decreased duodenal transepithelial resistance (TER), an effect also reversed by SCH-23390. A strong immunofluorescence signal for D 5 R, but not D 1 R, was observed in the duodenum of control rat. In human D 5 R knock-in transgenic mice, duodenal mucosa displayed an increased basal I SC with high FITC-dextran permeability and decreased TER with a lowered expression of tight junction proteins, suggesting attenuated duodenal barrier function in these transgenic mice. D 5 R knock-down transgenic mice manifested a decreased basal I SC with lowered FITC-dextran permeability. Moreover, an increased FITC-dextran permeability combined with decreased TER and tight junction protein expression in duodenal mucosa were also observed in HEnD rats. This study demonstrates, for the first time, that DA enhances duodenal permeability of control rat via D 5 R, which provides new experimental and theoretical evidence for the influence of DA on duodenal epithelial barrier function. © 2016 Scandinavian Physiological Society. Published by John Wiley & Sons Ltd.

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

    Science.gov (United States)

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

    2017-08-30

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

  18. INTESTINAL PERMEABILITY IN PEDIATRIC GASTROENTEROLOGY

    NARCIS (Netherlands)

    VANELBURG, RM; UIL, JJ; DEMONCHY, JGR; HEYMANS, HSA

    1992-01-01

    The role of the physiologic barrier function of the small bowel and its possible role in health and disease has attracted much attention over the past decade. The intestinal mucosal barrier for luminal macromolecules and microorganism is the result of non-immunologic and immunologic defense

  19. Quantifying Evaporation in a Permeable Pavement System

    Science.gov (United States)

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

  20. Permeable Pavement Research - Edison, New Jersey

    Science.gov (United States)

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

  1. 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…

  2. Passivity and Evolutionary Game Dynamics

    KAUST Repository

    Park, Shinkyu; Shamma, Jeff S.; Martins, Nuno C.

    2018-01-01

    This paper investigates an energy conservation and dissipation -- passivity -- aspect of dynamic models in evolutionary game theory. We define a notion of passivity using the state-space representation of the models, and we devise systematic methods to examine passivity and to identify properties of passive dynamic models. Based on the methods, we describe how passivity is connected to stability in population games and illustrate stability of passive dynamic models using numerical simulations.

  3. Passivity and Evolutionary Game Dynamics

    KAUST Repository

    Park, Shinkyu

    2018-03-21

    This paper investigates an energy conservation and dissipation -- passivity -- aspect of dynamic models in evolutionary game theory. We define a notion of passivity using the state-space representation of the models, and we devise systematic methods to examine passivity and to identify properties of passive dynamic models. Based on the methods, we describe how passivity is connected to stability in population games and illustrate stability of passive dynamic models using numerical simulations.

  4. Quantifying porosity, compressibility and permeability in Shale

    DEFF Research Database (Denmark)

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

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

  5. Viscous fingering with permeability heterogeneity

    International Nuclear Information System (INIS)

    Tan, C.; Homsy, G.M.

    1992-01-01

    Viscous fingering in miscible displacements in the presence of permeability heterogeneities is studied using two-dimensional simulations. The heterogeneities are modeled as stationary random functions of space with finite correlation scale. Both the variance and scale of the heterogeneities are varied over modest ranges. It is found that the fingered zone grows linearly in time in a fashion analogous to that found in homogeneous media by Tan and Homsy [Phys. Fluids 31, 1330 (1988)], indicating a close coupling between viscous fingering on the one hand and flow through preferentially more permeable paths on the other. The growth rate of the mixing zone increases monotonically with the variance of the heterogeneity, as expected, but shows a maximum as the correlation scale is varied. The latter is explained as a ''resonance'' between the natural scale of fingers in homogeneous media and the correlation scale

  6. Aktiv kontra passiv forvaltning

    DEFF Research Database (Denmark)

    Bechmann, Ken L.; Pedersen, Lasse Heje

    2017-01-01

    Fordele og ulemper ved aktiv og passiv forvaltning har fået fornyet opmærksomhed blandt andet i forbindelse med den forestående implementering af MiFID II. Som bidrag til denne diskussion indeholder dette nummer af Finans/Invest tre artikler, der behandler aktiv og passiv forvaltning fra...... forskellige vinkler. Denne leder forklarer, hvorfor valget mellem aktiv og passiv forvaltning er mere kompliceret, end hvad man kunne tro ved første øjekast, og konkluderer, at der vil være plads til - og behov for - begge typer forvaltning....

  7. Most energetic passive states.

    Science.gov (United States)

    Perarnau-Llobet, Martí; Hovhannisyan, Karen V; Huber, Marcus; Skrzypczyk, Paul; Tura, Jordi; Acín, Antonio

    2015-10-01

    Passive states are defined as those states that do not allow for work extraction in a cyclic (unitary) process. Within the set of passive states, thermal states are the most stable ones: they maximize the entropy for a given energy, and similarly they minimize the energy for a given entropy. Here we find the passive states lying in the other extreme, i.e., those that maximize the energy for a given entropy, which we show also minimize the entropy when the energy is fixed. These extremal properties make these states useful to obtain fundamental bounds for the thermodynamics of finite-dimensional quantum systems, which we show in several scenarios.

  8. RCRA corrective measures using a permeable reactive iron wall US Coast Guard Support Center, Elizabeth City, North Carolina

    International Nuclear Information System (INIS)

    Schmithors, W.L.; Vardy, J.A.

    1997-01-01

    A chromic acid release was discovered at a former electroplating shop at the U.S. Coast Guard Support Center in Elizabeth City, North Carolina. Initial investigative activities indicated that chromic acid had migrated into the subsurface soils and groundwater. In addition, trichloroethylene (TCE) was also discovered in groundwater during subsequent investigations of the hexavalent chromium (Cr VI) plume. Corrective measures were required under the Resource Conservation and Recovery Act (RCRA). The in-situ remediation method, proposed under RCRA Interim Measures to passively treat the groundwater contaminants, uses reactive zero-valent iron to reductively dechlorinate the chlorinated compounds and to mineralize the hexavalent chromium. A 47 meter by 0.6 meter subsurface permeable iron wall was installed downgradient of the source area to a depth of 7 meters using a direct trenching machine. The iron filings were placed in the ground as the soils were excavated from the subsurface. This is the first time that direct trenching was used to install reactive zero-valent iron filings. Over 250 metric tons of iron filings were used as the reactive material in the barrier wall. Installation of the iron filings took one full day. Extensive negotiations with regulatory agencies were required to use this technology under the current facility Hazardous Waste Management Permit. All waste soils generated during the excavation activities were contained and treated on site. Once contaminant concentrations were reduced the waste soils were used as fill material

  9. 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

  10. Techniques for active passivation

    Science.gov (United States)

    Roscioli, Joseph R.; Herndon, Scott C.; Nelson, Jr., David D.

    2016-12-20

    In one embodiment, active (continuous or intermittent) passivation may be employed to prevent interaction of sticky molecules with interfaces inside of an instrument (e.g., an infrared absorption spectrometer) and thereby improve response time. A passivation species may be continuously or intermittently applied to an inlet of the instrument while a sample gas stream is being applied. The passivation species may have a highly polar functional group that strongly binds to either water or polar groups of the interfaces, and once bound presents a non-polar group to the gas phase in order to prevent further binding of polar molecules. The instrument may be actively used to detect the sticky molecules while the passivation species is being applied.

  11. Passive radon daughter dosimeters

    International Nuclear Information System (INIS)

    McElroy, R.G.C.; Johnson, J.R.

    1986-03-01

    On the basis of an extensive review of the recent literature concerning passive radon daughter dosimeters, we have reached the following conclusions: 1) Passive dosimeters for measuring radon are available and reliable. 2) There does not presently exist an acceptable passive dosimeter for radon daughters. There is little if any hope for the development of such a device in the foreseeable future. 3) We are pessimistic about the potential of 'semi-passive dosimeters' but are less firm about stating categorically that these devices cannot be developed into a useful radon daughter dosimeter. This report documents and justifies these conclusions. It does not address the question of the worker's acceptance of these devices because at the present time, no device is sufficiently advanced for this question to be meaningful. 118 refs

  12. Passive Mixing inside Microdroplets

    Directory of Open Access Journals (Sweden)

    Chengmin Chen

    2018-04-01

    Full Text Available Droplet-based micromixers are essential units in many microfluidic devices for widespread applications, such as diagnostics and synthesis. The mixers can be either passive or active. When compared to active methods, the passive mixer is widely used because it does not require extra energy input apart from the pump drive. In recent years, several passive droplet-based mixers were developed, where mixing was characterized by both experiments and simulation. A unified physical understanding of both experimental processes and simulation models is beneficial for effectively developing new and efficient mixing techniques. This review covers the state-of-the-art passive droplet-based micromixers in microfluidics, which mainly focuses on three aspects: (1 Mixing parameters and analysis method; (2 Typical mixing element designs and the mixing characters in experiments; and, (3 Comprehensive introduction of numerical models used in microfluidic flow and diffusion.

  13. Economic alternatives for containment barriers

    International Nuclear Information System (INIS)

    Nicholson, P.J.; Jasperse, B.H.; Fisher, M.J.

    1997-01-01

    Fixation, barriers, and containment of existing landfills and other disposal areas are often performed by insitu auger type soil mixing and jet grouting. Cement or other chemical reagents are mixed with soil to form both vertical and horizontal barriers. Immobilization of contaminants can be economically achieved by mixing soil and the contaminants with reagents that solidify or stabilize the contaminated area. Developed in Japan, and relatively new to the United States, the first large scale application was for a vertical barrier at the Jackson Lake Dam project in 1986. This technology has grown in both the civil and environmental field since. The paper describes current United States practice for Deep Soil Mixing (over 12 meters in depth), and Shallow Soil Mixing for vertical barriers and stabilization/solidification, and Jet Grouting for horizontal and vertical barriers. Creating very low permeability barriers at depth with minimal surface return often makes these techniques economical when compared to slurry trenches. The paper will discuss equipment, materials, soil and strength parameters, and quality control

  14. CANDU passive shutdown systems

    Energy Technology Data Exchange (ETDEWEB)

    Hart, R S; Olmstead, R A [AECL CANDU, Sheridan Park Research Community, Mississauga, ON (Canada)

    1996-12-01

    CANDU incorporates two diverse, passive shutdown systems, independent of each other and from the reactor regulating system. Both shutdown systems function in the low pressure, low temperature, moderator which surrounds the fuel channels. The shutdown systems are functionally different, physically separate, and passive since the driving force for SDS1 is gravity and the driving force for SDS2 is stored energy. The physics of the reactor core itself ensures a degree of passive safety in that the relatively long prompt neutron generation time inherent in the design of CANDU reactors tend to retard power excursions and reduces the speed required for shutdown action, even for large postulated reactivity increases. All passive systems include a number of active components or initiators. Hence, an important aspect of passive systems is the inclusion of fail safe (activated by active component failure) operation. The mechanisms that achieve the fail safe action should be passive. Consequently the passive performance of the CANDU shutdown systems extends beyond their basic modes of operation to include fail safe operation based on natural phenomenon or stored energy. For example, loss of power to the SDS1 clutches results in the drop of the shutdown rods by gravity, loss of power or instrument air to the injection valves of SDS2 results in valve opening via spring action, and rigorous self checking of logic, data and timing by the shutdown systems computers assures a fail safe reactor trip through the collapse of a fluctuating magnetic field or the discharge of a capacitor. Event statistics from operating CANDU stations indicate a significant decrease in protection system faults that could lead to loss of production and elimination of protection system faults that could lead to loss of protection. This paper provides a comprehensive description of the passive shutdown systems employed by CANDU. (author). 4 figs, 3 tabs.

  15. Membrane barriers for radon gas flow restrictions

    International Nuclear Information System (INIS)

    Archibald, J.F.

    1984-08-01

    Research was performed to assess the feasibility of barrier membrane substances, for use within mining or associated high risk environments, in restricting the diffusion transport of radon gas quantities. Specific tests were conducted to determine permeability parameters of a variety of membrane materials with reference to radon flow capabilities. Tests were conducted both within laboratory and in-situ emanation environments where concentrations and diffusion flows of radon gas were known to exist. Equilibrium radon gas concentrations were monitored in initially radon-free chambers adjacent to gas sources, but separated by specified membrane substances. Membrane barrier effectiveness was demonstrated to result in reduced emanation concentrations of radon gas within the sampling chamber atmosphere. Minimum gas concentrations were evidenced where the barrier membrane material was shown to exhibit lowest radon permeability characteristics

  16. Pathophysiology of increased intestinal permeability in obstructive jaundice

    Science.gov (United States)

    Assimakopoulos, Stelios F; Scopa, Chrisoula D; Vagianos, Constantine E

    2007-01-01

    Despite advances in preoperative evaluation and postoperative care, intervention, especially surgery, for relief of obstructive jaundice still carries high morbidity and mortality rates, mainly due to sepsis and renal dysfunction. The key event in the pathophysiology of obstructive jaundice-associated complications is endotoxemia of gut origin because of intestinal barrier failure. This breakage of the gut barrier in obstructive jaundice is multi-factorial, involving disruption of the immunologic, biological and mechanical barrier. Experimental and clinical studies have shown that obstructive jaundice results in increased intestinal permeability. The mechanisms implicated in this phenomenon remain unresolved, but growing research interest during the last decade has shed light in our knowledge in the field. This review summarizes the current concepts in the pathophysiology of obstructive jaundice-induced gut barrier dysfunction, analyzing pivotal factors, such as altered intestinal tight junctions expression, oxidative stress and imbalance of enterocyte proliferation and apoptosis. Clinicians handling patients with obstructive jaundice should not neglect protecting the intestinal barrier function before, during and after intervention for the relief of this condition, which may improve their patients’ outcome. PMID:18161914

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

    African Journals Online (AJOL)

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

  18. cGMP and nitric oxide modulate thrombin-induced endothelial permeability : Regulation via different pathways in human aortic and umbilical vein endothelial cells

    NARCIS (Netherlands)

    Draijer, R.; Atsma, D.E.; Laarse, A. van der; Hinsbergh, V.W.M. van

    1995-01-01

    Previous studies have demonstrated that cGMP and cAMP reduce the endothelial permeability for fluids and macromolecules when the endothelial permeability is increased by thrombin. In this study, we have investigated the mechanism by which cGMP improves the endothelial barrier function and examined

  19. LEAK AND GAS PERMEABILITY TESTING DURING SOIL-GAS SAMPLING AT HAL'S CHEVRON LUST SITE IN GREEN RIVER, UTAH

    Science.gov (United States)

    The results of gas permeability and leak testing during active soil-gas sampling at Hal’s Chevron LUST Site in Green River, Utah are presented. This study was conducted to support development of a passive soil-gas sampling method. Gas mixtures containing helium and methane were...

  20. SALT ACCLIMATION OF TRITICUM-AESTIVUM BY CHOLINE CHLORIDE - PLANT-GROWTH, MINERAL-CONTENT, AND CELL-PERMEABILITY

    NARCIS (Netherlands)

    MANSOUR, MM; STADELMANN, EJ; LEESTADELMANN, OY

    1993-01-01

    Seedlings of a salt sensitive line of Triticum aestivum were grown in Hoagland solution supplemented with 100 mM NaCl following a pretreatment with choline chloride (ChCl). Changes in growth, mineral content of roots and shoots, and passive permeability of the cell membrane were measured. Relative

  1. 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)

  2. NucleDyne's passive containment system

    International Nuclear Information System (INIS)

    Falls, O.B. Jr.; Kleimola, F.W.

    1987-01-01

    A simple definition of the passive containment system is that it is a total safeguards system for light water reactors designed to prevent and contain any accidental release of radioactivity. Its passive features utilize the natural laws of physics and thermodynamics. The system encompasses three basic containments constructed as one integrated structure on the reactor building foundation. The primary containment encloses the reactor pressure vessel and coolant system and passive engineered safety systems and components. Auxiliary containment enclosures house auxiliary systems and components. Secondary containment (the reactor building), housing the primary and auxiliary containment structures, provides a second containment barrier as added defense-in-depth against leakage of radioactivity for all accidents assumed by the industry. The generic features of the passive containment system are applicable to both the boiling water reactors and the pressurized water reactors as standardized features for all power ranges. These features provide for a zero source term, the industry's ultimate safety goal. This paper relates to a four-loop pressurized water reactor

  3. Permeability of highly compacted bentonite

    International Nuclear Information System (INIS)

    Pusch, R.

    1980-12-01

    The object of the study was the water flow through the bentonite which is caused by hydraulic gradients. The study comprised laboratory tests and theoretical considerations. It was found that high bulk densities reduced the permeability to very low values. It was concluded that practically impervious conditions prevail when the gradients are low. Thus with a regional gradient of 10 -2 and a premeability of 10 -13 m/s the flow rate will not be higher than approximately 1 mm in 30 000 years. (G.B.)

  4. Engineered safeguards and passive safety features (safety analysis detailed report no. 6)

    Energy Technology Data Exchange (ETDEWEB)

    1988-01-15

    The Safety-Analysis Summary lists the reactor's safety aspects for passive and active prevention of severe accidents and mitigation of accident consequences, i.e., intrinsic and passive protections of the plant; intrinsic and passive protections of the core; inherent decay-heat removal systems; rapid-shutdown systems; four physical containment barriers. This report goes into further details regarding some of this aspects.

  5. Quantitative Raman microspectroscopy for water permeability parameters at a droplet interface bilayer.

    Science.gov (United States)

    Braziel, S; Sullivan, K; Lee, S

    2018-01-29

    Using confocal Raman microspectroscopy, we derive parameters for bilayer water transport across an isolated nanoliter aqueous droplet pair. For a bilayer formed with two osmotically imbalanced and adherent nanoliter aqueous droplets in a surrounding oil solvent, a droplet interface bilayer (DIB), the water permeability coefficient across the lipid bilayer was determined from monitoring the Raman scattering from the C[triple bond, length as m-dash]N stretching mode of K 3 Fe(CN) 6 as a measure of water uptake into the swelling droplet of a DIB pair. We also derive passive diffusional permeability coefficient for D 2 O transport across a droplet bilayer using O-D Raman signal. This method provides a significant methodological advance in determining water permeability coefficients in a convenient and reliable way.

  6. Measure Guideline: Passive Vents

    Energy Technology Data Exchange (ETDEWEB)

    Berger, David [Consortium for Advanced Residential Buildings, Norwalk, CT (United States); Neri, Robin [Consortium for Advanced Residential Buildings, Norwalk, CT (United States)

    2016-02-05

    This document addresses the use of passive vents as a source of outdoor air in multifamily buildings. The challenges associated with implementing passive vents and the factors affecting performance are outlined. A comprehensive design methodology and quantified performance metrics are provided. Two hypothetical design examples are provided to illustrate the process. This document is intended to be useful to designers, decision-makers, and contractors implementing passive ventilation strategies. It is also intended to be a resource for those responsible for setting high-performance building program requirements, especially pertaining to ventilation and outdoor air. To ensure good indoor air quality, a dedicated source of outdoor air is an integral part of high-performance buildings. Presently, there is a lack of guidance pertaining to the design and installation of passive vents, resulting in poor system performance. This report details the criteria necessary for designing, constructing, and testing passive vent systems to enable them to provide consistent and reliable levels of ventilation air from outdoors.

  7. The low/high BCS permeability class boundary: physicochemical comparison of metoprolol and labetalol.

    Science.gov (United States)

    Zur, Moran; Gasparini, Marisa; Wolk, Omri; Amidon, Gordon L; Dahan, Arik

    2014-05-05

    Although recognized as overly conservative, metoprolol is currently the common low/high BCS permeability class boundary reference compound, while labetalol was suggested as a potential alternative. The purpose of this study was to identify the various characteristics that the optimal marker should exhibit, and to investigate the suitability of labetalol as the permeability class reference drug. Labetalol's BCS solubility class was determined, and its physicochemical properties and intestinal permeability were thoroughly investigated, both in vitro and in vivo in rats, considering the complexity of the whole of the small intestine. Labetalol was found to be unequivocally a high-solubility compound. In the pH range throughout the small intestine (6.5-7.5), labetalol exhibited pH-dependent permeability, with higher permeability at higher pH values. While in vitro octanol-buffer partitioning (Log D) values of labetalol were significantly higher than those of metoprolol, the opposite was evident in the in vitro PAMPA permeability assay. The results of the in vivo perfusion studies in rats lay between the two contradictory in vitro studies; metoprolol was shown to have moderately higher rat intestinal permeability than labetalol. Theoretical distribution of the ionic species of the drugs was in corroboration with the experimental in vitro and the in vivo data. We propose three characteristics that the optimal permeability class reference drug should exhibit: (1) fraction dose absorbed in the range of 90%; (2) the optimal marker drug should be absorbed largely via passive transcellular permeability, with no/negligible carrier-mediated active intestinal transport (influx or efflux); and (3) the optimal marker drug should preferably be nonionizable. The data presented in this paper demonstrate that neither metoprolol nor labetalol can be regarded as optimal low/high-permeability class boundary standard. While metoprolol is too conservative due to its complete absorption

  8. Relative permeability of the endothelium and epithelium of rabbit lungs

    International Nuclear Information System (INIS)

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

    1986-01-01

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

  9. Thermal loading of bentonite. Impact on hydromechanics and permeability

    Energy Technology Data Exchange (ETDEWEB)

    Zihms, Stephanie G.; Harrington, Jon [British Geological Survey, Nickerhill Keyworth (United Kingdom)

    2015-07-01

    Due to its favorable properties, in particular, low permeability and swelling capacity, bentonite has been favored as an engineered barrier and backfill material for the geological storage of radioactive waste. To ensure safe long-term performance it is important to understand any changes in these properties when the material is subject to heat emitting waste. As such, this study will investigate the hydro-mechanical response of bentonite under multi-step thermal loading subject to a constant volume boundary condition. The experimental set up allows continuous measurements of hydraulic and mechanical response during each phase of the thermal cycle. The constant volume cell was placed inside an oven and connected to a hydraulic system with the water reservoir located externally. A pressure gradient of 4 MPa was placed across the sample for the duration of the test in order to map the evolution of permeability. After initial hydration of the bentonite, in this case signified by reaching the asymptote in total stress, the temperature was raised in 20 C increments from 20 to 80 C followed by a final 10 C step to reach 90 C. Each temperature was held constant for at least 7-10 days to allow the stresses and hydraulic transients to equilibrate. This data set will provide an insight into the hydromechanical behavior of the bentonite and the evolution of its permeability when exposed to elevated temperatures.

  10. Steam-water relative permeability

    Energy Technology Data Exchange (ETDEWEB)

    Ambusso, W.; Satik, C.; Home, R.N. [Stanford Univ., CA (United States)

    1997-12-31

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

  11. Material Barriers to Diffusive Mixing

    Science.gov (United States)

    Haller, George; Karrasch, Daniel

    2017-11-01

    Transport barriers, as zero-flux surfaces, are ill-defined in purely advective mixing in which the flux of any passive scalar is zero through all material surfaces. For this reason, Lagrangian Coherent Structures (LCSs) have been argued to play the role of mixing barriers as most repelling, attracting or shearing material lines. These three kinematic concepts, however, can also be defined in different ways, both within rigorous mathematical treatments and within the realm of heuristic diagnostics. This has lead to a an ever-growing number of different LCS methods, each generally identifying different objects as transport barriers. In this talk, we examine which of these methods have actual relevance for diffusive transport barriers. The latter barriers are arguably the practically relevant inhibitors in the mixing of physically relevant tracers, such as temperature, salinity, vorticity or potential vorticity. We demonstrate the role of the most effective diffusion barriers in analytical examples and observational data. Supported in part by the DFG Priority Program on Turbulent Superstructures.

  12. ROS-activated calcium signaling mechanisms regulating endothelial barrier function.

    Science.gov (United States)

    Di, Anke; Mehta, Dolly; Malik, Asrar B

    2016-09-01

    Increased vascular permeability is a common pathogenic feature in many inflammatory diseases. For example in acute lung injury (ALI) and its most severe form, the acute respiratory distress syndrome (ARDS), lung microvessel endothelia lose their junctional integrity resulting in leakiness of the endothelial barrier and accumulation of protein rich edema. Increased reactive oxygen species (ROS) generated by neutrophils (PMNs) and other inflammatory cells play an important role in increasing endothelial permeability. In essence, multiple inflammatory syndromes are caused by dysfunction and compromise of the barrier properties of the endothelium as a consequence of unregulated acute inflammatory response. This review focuses on the role of ROS signaling in controlling endothelial permeability with particular focus on ALI. We summarize below recent progress in defining signaling events leading to increased endothelial permeability and ALI. Copyright © 2016 Elsevier Ltd. All rights reserved.

  13. Attenuation of pyrite oxidation with a fly ash pre-barrier: Reactive transport modelling of column experiments

    Energy Technology Data Exchange (ETDEWEB)

    Perez-Lopez, R.; Cama, J.; Nieto, J.M.; Ayora, C.; Saaltink, M.W. [University of Huelva, Huelva (Spain). Dept. of Geology

    2009-09-15

    Conventional permeable reactive barriers (PRBs) for passive treatment of groundwater contaminated by acid mine drainage (AMD) use limestone as reactive material that neutralizes water acidity. However, the limestone-alkalinity potential ceases as inevitable precipitation of secondary metal-phases on grain surfaces occurs, limiting its efficiency. In the present study, fly ash derived from coal combustion is investigated as an alternative alkalinity generating material for the passive treatment of AMD using solution-saturated column experiments. Unlike conventional systems, the utilization of fly ash in a pre-barrier to intercept the non-polluted recharge water before this water reacts with pyrite-rich wastes is proposed. Chemical variation in the columns was interpreted with the reactive transport code RETRASO. In parallel, kinetics of fly ash dissolution at alkaline pH were studied using flow-through experiments and incorporated into the model. In a saturated column filled solely with pyritic sludge-quartz sand (1: 10), oxidation took place at acidic conditions (pH 3.7). According to SO{sub 4}{sup 2-} release and pH, pyrite dissolution occurred favourably in the solution-saturated porous medium until dissolved O{sub 2} was totally consumed. In a second saturated column, pyrite oxidation took place at alkaline conditions (pH 10.45) as acidity was neutralized by fly ash dissolution in a previous level. At this pH Fe release from pyrite dissolution was immediately depleted as Fe-oxy(hydroxide) phases that precipitated on the pyrite grains, forming Fe-coatings (microencapsulation). With time, pyrite microencapsulation inhibited oxidation in practically 97% of the pyritic sludge. Rapid pyrite-surface passivation decreased its reactivity, preventing AMD production in the relatively short term.

  14. Clogging in permeable concrete: A review.

    Science.gov (United States)

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

    2017-05-15

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

  15. Different Methods of Predicting Permeability in Shale

    DEFF Research Database (Denmark)

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

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

  16. Nuclear reactor vessel fuel thermal insulating barrier

    Science.gov (United States)

    Keegan, C. Patrick; Scobel, James H.; Wright, Richard F.

    2013-03-19

    The reactor vessel of a nuclear reactor installation which is suspended from the cold leg nozzles in a reactor cavity is provided with a lower thermal insulating barrier spaced from the reactor vessel that has a hemispherical lower section that increases in volume from the center line of the reactor to the outer extent of the diameter of the thermal insulating barrier and smoothly transitions up the side walls of the vessel. The space between the thermal insulating harrier and the reactor vessel forms a chamber which can be flooded with cooling water through passive valving to directly cool the reactor vessel in the event of a severe accident. The passive inlet valve for the cooling water includes a buoyant door that is normally maintained sealed under its own weight and floats open when the cavity is Hooded. Passively opening steam vents are also provided.

  17. Constructing passive houses

    Energy Technology Data Exchange (ETDEWEB)

    Oehler, S. [Oehler Faigle Archkom Solar Architektur, Bretten (Germany)

    2005-07-01

    Everybody can learn to build energy-efficient. It needs theoretical and practical experience. 1997 we built the first freestanding Passive House in Europe, the Passive House Oehler. There had been a lot of questions, starting with the insecurity, whether the calculation program of the Passive House Institute, the PHPP, is working properly in our case. Nobody knew at that time because nobody tried it out before. It took us a lot of time to find out and every detail of the construction hat to be invented to meet the very high demand of thermal quality. All the following houses needed less time and had fewer open questions, adding one piece of experience with every building. 2002 we realised the biggest Passive House, the office building Energon Ulm with 420 working spaces. In the meantime we have learned a lot like how to produce prefabricated timber elements for the facades, providing good insulation, air tightness and avoiding serious thermal bridges. We have proofed, that any kind of building type can be a Passive House. And with increasing experience the freedom of design and construction is growing. Even the economical efficiency increased. The Energon Ulm is providing a much better indoor climate than any other office building and was build 10 % cheaper than an average German office building. At present the Passive House Standard is the most efficient solution for the user to live in the desired comfort zone between 20 C and 25 C. This zone of individual feeling-well can be described with the term ''operative temperature''. This term is defined by factors like air temperature, radiation temperature of warm and cold surfaces, air speed and humidity. The result of all these factors has to be within 18 C to 25 C without accepting one of the factors getting extreme.

  18. Passive containment system

    International Nuclear Information System (INIS)

    Kleimola, F.W.

    1977-01-01

    Disclosed is a containment system that provides complete protection entirely by passive means for the loss of coolant accident in a nuclear power plant and wherein all stored energy released in the coolant blowdown is contained and absorbed while the nuclear fuel is prevented from over-heating by a high containment back-pressure and a reactor vessel refill system. The primary containment vessel is restored to a high sub-atmospheric pressure within a few minutes after accident initiation and the decay heat is safely transferred to the environment while radiolytic hydrogen is contained by passive means. 20 claims, 14 figures

  19. Wireless passive radiation sensor

    Science.gov (United States)

    Pfeifer, Kent B; Rumpf, Arthur N; Yelton, William G; Limmer, Steven J

    2013-12-03

    A novel measurement technique is employed using surface acoustic wave (SAW) devices, passive RF, and radiation-sensitive films to provide a wireless passive radiation sensor that requires no batteries, outside wiring, or regular maintenance. The sensor is small (<1 cm.sup.2), physically robust, and will operate unattended for decades. In addition, the sensor can be insensitive to measurement position and read distance due to a novel self-referencing technique eliminating the need to measure absolute responses that are dependent on RF transmitter location and power.

  20. Glomerular barrier behaves as an atomically precise bandpass filter in a sub-nanometre regime

    Science.gov (United States)

    Du, Bujie; Jiang, Xingya; Das, Anindita; Zhou, Qinhan; Yu, Mengxiao; Jin, Rongchao; Zheng, Jie

    2017-11-01

    The glomerular filtration barrier is known as a 'size cutoff' slit, which retains nanoparticles or proteins larger than 6-8 nm in the body and rapidly excretes smaller ones through the kidneys. However, in the sub-nanometre size regime, we have found that this barrier behaves as an atomically precise 'bandpass' filter to significantly slow down renal clearance of few-atom gold nanoclusters (AuNCs) with the same surface ligands but different sizes (Au18, Au15 and Au10-11). Compared to Au25 (∼1.0 nm), just few-atom decreases in size result in four- to ninefold reductions in renal clearance efficiency in the early elimination stage, because the smaller AuNCs are more readily trapped by the glomerular glycocalyx than larger ones. This unique in vivo nano-bio interaction in the sub-nanometre regime also slows down the extravasation of sub-nanometre AuNCs from normal blood vessels and enhances their passive targeting to cancerous tissues through an enhanced permeability and retention effect. This discovery highlights the size precision in the body's response to nanoparticles and opens a new pathway to develop nanomedicines for many diseases associated with glycocalyx dysfunction.

  1. Reactive barrier technologies for treatment of contaminated groundwater at Rocky Flats

    International Nuclear Information System (INIS)

    Marozas, D.C.; Bujewski, G.E.; Castaneda, N.

    1997-01-01

    The U.S. Department of Energy (DOE) Office of Science and Technology Subsurface Contaminants Focus Area is supporting the investigation of reactive barrier technologies to mitigate the risks associated with mixed organic/radioactive waste at several DOE sites. Groundwater from a small contaminated plume at the Rocky Flats Environmental Technology Site (RFETS) is being used to evaluate passive reactive material treatment. Permeable reactive barriers which intercept contaminants and destroy the VOC component while containing radionuclides are attractive for a number of reasons relating to public and regulatory acceptance. In situ treatment keeps contaminants away from the earth's surface, there is no above-ground treatment equipment that could expose workers and the public and operational costs are expected to be lower than currently used technologies. This paper will present results from preliminary site characterization and in-field small-scale column testing of reactive materials at RFETS. Successful demonstration is expected to lead to full-scale implementation of the technology at several DOE sites, including Rocky Flats

  2. Passive versus active tumor targeting using RGD- and NGR-modified polymeric nanomedicines

    NARCIS (Netherlands)

    Kunjachan, Sijumon; Pola, Robert; Gremse, Felix; Theek, Benjamin; Ehling, Josef; Moeckel, Diana; Hermanns-Sachweh, Benita; Pechar, Michal; Ulbrich, Karel; Hennink, Wim E.; Storm, Gert; Lederle, Wiltrud; Kiessling, Fabian; Lammers, Twan

    2014-01-01

    Enhanced permeability and retention (EPR) and the (over-) expression of angiogenesis-related surface receptors are key features of tumor blood vessels. As a consequence, EPR-mediated passive and Arg-Gly-Asp (RGD) and Asn-Gly-Arg (NGR) based active tumor targeting have received considerable attention

  3. 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

  4. Heterogeneity of brain blood flow and permeability during acute hypertension

    International Nuclear Information System (INIS)

    Baumbach, G.L.; Heistad, D.D.

    1985-01-01

    The purpose of this study was to examine regional autoregulation of blood flow in the brain during acute hypertension. In anesthetized cats severe hypertension increased blood flow more in cerebrum (159%) and cerebellum (106%) than brain stem (58%). In contrast to the heterogeneous autoregulatory response, hypocapnia produced uniform vasoconstriction in the brain. The authors also compared vasodilatation during severe hypertension with vasodilatation during hypercapnia. During hypercapnia, blood flow increased as much in brain stem, as in cerebrum and cerebellum. Thus, regional differences in autoregulation appear to be specific for autoregulatory stimulus and are not secondary to nonspecific differences in vasoconstrictor or vasodilator capacity. To determine whether the blood-brain barrier is more susceptible to hypertensive disruption in regions with less effective autoregulation, permeability of the barrier was quantitated with 125 I-albumin. Severe hypertension produced disruption of the barrier in cerebrum but not in brain stem. Thus, there are parallel differences in effectiveness of autoregulation and susceptibility to disruption of the blood-brain barrier in different regions of the brain

  5. 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.

  6. Low Permeability Polyimide Insulation, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — Resodyn Technologies proposes a new technology that enables the application of polyimide based cryogenic insulation with low hydrogen permeability. This effort...

  7. Modelling of water permeability in cementitious materials

    DEFF Research Database (Denmark)

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

    2006-01-01

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

  8. Permeability - Fluid Pressure - Stress Relationship in Fault Zones in Shales

    Science.gov (United States)

    Henry, P.; Guglielmi, Y.; Morereau, A.; Seguy, S.; Castilla, R.; Nussbaum, C.; Dick, P.; Durand, J.; Jaeggi, D.; Donze, F. V.; Tsopela, A.

    2016-12-01

    Fault permeability is known to depend strongly on stress and fluid pressures. Exponential relationships between permeability and effective pressure have been proposed to approximate fault response to fluid pressure variations. However, the applicability of these largely empirical laws remains questionable, as they do not take into account shear stress and shear strain. A series of experiments using mHPP probes have been performed within fault zones in very low permeability (less than 10-19 m2) Lower Jurassic shale formations at Tournemire (France) and Mont Terri (Switzerland) underground laboratories. These probes allow to monitor 3D displacement between two points anchored to the borehole walls at the same time as fluid pressure and flow rate. In addition, in the Mont-Terri experiment, passive pressure sensors were installed in observation boreholes. Fracture transmissivity was estimated from single borehole pulse test, constant pressure injection tests, and cross-hole tests. It is found that the transmissivity-pressure dependency can be approximated with an exponential law, but only above a pressure threshold that we call the Fracture Opening Threshold (F.O.P). The displacement data show a change of the mechanical response across the F.O.P. The displacement below the F.O.P. is dominated by borehole response, which is mostly elastic. Above F.O.P., the poro-elasto-plastic response of the fractures dominates. Stress determinations based on previous work and on the analysis of slip data from mHPPP probe indicate that the F.O.P. is lower than the least principal stress. Below the F.O.P., uncemented fractures retain some permeability, as pulse tests performed at low pressures yield diffusivities in the range 10-2 to 10-5 m2/s. Overall, this dual behavior appears consistent with the results of CORK experiments performed in accretionary wedge decollements. Results suggest (1) that fault zones become highly permeable when approaching the critical Coulomb threshold (2

  9. Comparative study of four immortalized human brain capillary endothelial cell lines, hCMEC/D3, hBMEC, TY10, and BB19, and optimization of culture conditions, for an in vitro blood–brain barrier model for drug permeability studies

    OpenAIRE

    Eigenmann, Daniela E; Xue, Gongda; Kim, Kwang S; Moses, Ashlee V; Hamburger, Matthias; Oufir, Mouhssin

    2013-01-01

    Background: Reliable human in vitro blood brain barrier (BBB) models suitable for high throughput screening are urgently needed in early drug discovery and development for assessing the ability of promising bioactive compounds to overcome the BBB. To establish an improved human in vitro BBB model we compared four currently available and well characterized immortalized human brain capillary endothelial cell lines hCMEC/D3 hBMEC TY10 and BB19 with respect to barrier tightness and paracellular p...

  10. Application of polycrystalline diffusion barriers

    International Nuclear Information System (INIS)

    Tsymbal, V.A.; Kolupaev, I.N.

    2010-01-01

    Degradation of contacts of the electronic equipment at the raised temperatures is connected with active diffusion redistribution of components contact - metalized systems (CMS) and phase production on interphase borders. One of systems diffusion barriers (DB) are polycrystalline silicide a film, in particular silicides of the titan. Reception disilicide the titan (TiSi 2 ) which on the parameters is demanded for conditions of microelectronics from known silicides of system Ti-Si, is possible as a result of direct reaction of a film of the titan and a substrate of silicon, and at sedimentation of layer Ti-Si demanded stoichiometric structure. Simultaneously there is specific problem polycrystalline diffusion a barrier (PDB): the polycrystalline provides structural balance and metastability film disilicide, but leaves in it borders of grains - easy local ways of diffusion. In clause the analysis diffusion permeability polycrystalline and polyphase DB is made and recommendations for practical methods of increase of blocking properties PDB are made.

  11. Passiv-Sammler

    OpenAIRE

    Fritsche, U.

    1991-01-01

    The invention relates to a passive collector for air pollution for the determination of emission rates for dry and wet deposits on construction materials such as natural stone, whereby the collector has a surrogate surface of the stone under investigation, the surrogate surface being linked to a collecting vessel such that any dry or wet contamination occurring can be collected.

  12. Passive houses in Norway

    Energy Technology Data Exchange (ETDEWEB)

    Halse, Andreas

    2008-12-15

    The paper analyzes the introduction of passive houses in the Norwegian house market. Passive houses are houses with extremely low levels of energy consumption for heating, and have not yet been built in Norway, but have started to enter the market in Germany and some other countries. The construction sector is analyzed as a sectoral innovation system. The different elements of the innovation system are studied. This includes government agencies, producers, consumers, finance and education. The analysis shows that passive and low-energy houses are on the verge of market breakthrough. This can partly be explained by economic calculations, and partly by processes of learning and change in the institutional set-up of the sector. The construction sector is a sector characterized by low innovative intensity and little interaction between different agents. Those working to promote passive houses have to some extent managed to cope with these challenges. This has happened by breaking away from the traditional focus of Norwegian energy efficiency policies on technology and the economically rational agents, by instead focusing on knowledge and institutional change at the level of the producers. (Author)

  13. Hood River Passive House

    Energy Technology Data Exchange (ETDEWEB)

    Hales, David [BA-PIRC, Spokane, WA (United States)

    2014-01-01

    The Hood River Passive Project was developed by Root Design Build of Hood River Oregon using the Passive House Planning Package (PHPP) to meet all of the requirements for certification under the European Passive House standards. The Passive House design approach has been gaining momentum among residential designers for custom homes and BEopt modeling indicates that these designs may actually exceed the goal of the U.S. Department of Energy's (DOE) Building America program to "reduce home energy use by 30%-50% (compared to 2009 energy codes for new homes). This report documents the short term test results of the Shift House and compares the results of PHPP and BEopt modeling of the project. The design includes high R-Value assemblies, extremely tight construction, high performance doors and windows, solar thermal DHW, heat recovery ventilation, moveable external shutters and a high performance ductless mini-split heat pump. Cost analysis indicates that many of the measures implemented in this project did not meet the BA standard for cost neutrality. The ductless mini-split heat pump, lighting and advanced air leakage control were the most cost effective measures. The future challenge will be to value engineer the performance levels indicated here in modeling using production based practices at a significantly lower cost.

  14. Passive THz metamaterials

    DEFF Research Database (Denmark)

    Lavrinenko, Andrei; Malureanu, Radu; Zalkovskij, Maksim

    2012-01-01

    In this work we present our activities in the fabrication and characterization of passive THz metamaterials. We use two fabrication processes to develop metamaterials either as free-standing metallic membranes or patterned metallic multi-layers on the substrates to achieve different functionalities...

  15. Artificial neural network models for prediction of intestinal permeability of oligopeptides

    Directory of Open Access Journals (Sweden)

    Kim Min-Kook

    2007-07-01

    Full Text Available Abstract Background Oral delivery is a highly desirable property for candidate drugs under development. Computational modeling could provide a quick and inexpensive way to assess the intestinal permeability of a molecule. Although there have been several studies aimed at predicting the intestinal absorption of chemical compounds, there have been no attempts to predict intestinal permeability on the basis of peptide sequence information. To develop models for predicting the intestinal permeability of peptides, we adopted an artificial neural network as a machine-learning algorithm. The positive control data consisted of intestinal barrier-permeable peptides obtained by the peroral phage display technique, and the negative control data were prepared from random sequences. Results The capacity of our models to make appropriate predictions was validated by statistical indicators including sensitivity, specificity, enrichment curve, and the area under the receiver operating characteristic (ROC curve (the ROC score. The training and test set statistics indicated that our models were of strikingly good quality and could discriminate between permeable and random sequences with a high level of confidence. Conclusion We developed artificial neural network models to predict the intestinal permeabilities of oligopeptides on the basis of peptide sequence information. Both binary and VHSE (principal components score Vectors of Hydrophobic, Steric and Electronic properties descriptors produced statistically significant training models; the models with simple neural network architectures showed slightly greater predictive power than those with complex ones. We anticipate that our models will be applicable to the selection of intestinal barrier-permeable peptides for generating peptide drugs or peptidomimetics.

  16. Barrier Systems

    NARCIS (Netherlands)

    Heteren, S. van

    2015-01-01

    Barrier-system dynamics are a function of antecedent topography and substrate lithology, Relative sea-level (RSL) changes, sediment availability and type, climate, vegetation type and cover, and various aero- and hydrodynamic processes during fair-weather conditions and extreme events. Global change

  17. The measurement of water vapor permeability of glove materials using dilute tritiated water

    International Nuclear Information System (INIS)

    Doughty, D.H.

    1982-01-01

    As fusion technology progresses, there will be an increasing need to handle tritium and tritiated compounds. Protective clothing, especially drybox gloves, must be an effective barrier to minimize worker exposure. The water vapor permeability of glove materials and finished glove constructions is a crucial property of drybox gloves and is not sufficiently well characterized. We have built an apparatus that measures water vapor permeability of elastomers using dilute tritiated water. The technique is more sensitive than other methods currently available and allows us to make measurements on materials and under conditions previously inaccessible. In particular, we present results on laminated drybox gloves for which data is not currently available. (orig.)

  18. Intrinsically Passive Handling and Grasping

    NARCIS (Netherlands)

    Stramigioli, Stefano; Scherpen, Jacquelien M.A.; Khodabandehloo, Koorosh

    2000-01-01

    The paper presents a control philosophy called Intrinsically Passive Control, which has the feature to properly behave during interaction with any passive objects. The controlled robot will never become unstable due to the physical structure of the controller.

  19. 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.

  20. Crustal permeability: Introduction to the special issue

    Science.gov (United States)

    Ingebritsen, Steven E.; Gleeson, Tom

    2015-01-01

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

  1. [The blood-brain barrier in ageing persons].

    Science.gov (United States)

    Haaning, Nina; Damsgaard, Else Marie; Moos, Torben

    2018-03-26

    Brain capillary endothelial cells (BECs) form the ultra-tight blood-brain barrier (BBB). The permeability of the BBB increases with increasing age and neurovascular and neurodegenerative diseases. Major defects of the BBB can be initiated by increased permeability to plasma proteins in small arteriosclerotic arteries and release of proteins from degenerating neurons into the brain extracellular space. These proteins deposit in perivascular spaces, and subsequently negatively influence the BECs leading to decreased expression of barrier proteins. Detection of BBB defects by the use of non-invasive techniques is relevant for clinical use in settings with advanced age and severe brain disorders.

  2. Effect of temperature on sandstone permeability

    DEFF Research Database (Denmark)

    Rosenbrand, Esther; Kjøller, Claus

    Hot water injection in geothermal sandstone aquifers is considered for seasonal energy storage in Denmark. However, an increase in the aquifer temperature might reduce permeability, and thereby increase production costs. An understanding of the factors that control permeability is required in order...... and the Klinkenberg procedure showed the expected correlation between the two measures, however, differences could be around one order of magnitude. In tight gas sandstones, permeability is often sensitive to net stress, which might change due to the pore pressure change in the Klinkenberg procedure. Besides...... affecting the Klinkenberg procedure, the combined effect of slip and changes in permeability would affect production during pressure depletion in tight gas sandstone reservoirs; therefore effects of gas slip and net stress on permeability were combined in a model based on the Klinkenberg equation. A lower...

  3. Microorganism Removal in Permeable Pavement Parking Lots ...

    Science.gov (United States)

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

  4. Neutrophils Compromise Retinal Pigment Epithelial Barrier Integrity

    Directory of Open Access Journals (Sweden)

    Jiehao Zhou

    2010-01-01

    Full Text Available We hypothesized that neutrophils and their secreted factors mediate breakdown of the integrity of the outer blood-retina-barrier by degrading the apical tight junctions of the retinal pigment epithelium (RPE. The effect of activated neutrophils or neutrophil cell lysate on apparent permeability of bovine RPE-Choroid explants was evaluated by measuring [H] mannitol flux in a modified Ussing chamber. The expression of matrix metalloproteinase- (MMP- 9 in murine peritoneal neutrophils, and the effects of neutrophils on RPE tight-junction protein expression were assessed by confocal microscopy and western blot. Our results revealed that basolateral incubation of explants with neutrophils decreased occludin and ZO-1 expression at 1 and 3 hours and increased the permeability of bovine RPE-Choroid explants by >3-fold (P<.05. Similarly, basolateral incubation of explants with neutrophil lysate decreased ZO-1 expression at 1 and 3 hours (P<.05 and increased permeability of explants by 75%. Further, we found that neutrophils prominently express MMP-9 and that incubation of explants with neutrophils in the presence of anti-MMP-9 antibody inhibited the increase in permeability. These data suggest that neutrophil-derived MMP-9 may play an important role in disrupting the integrity of the outer blood-retina barrier.

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

    Science.gov (United States)

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

    2012-04-01

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

  6. Passivation of black phosphorus saturable absorbers for reliable pulse formation of fiber lasers.

    Science.gov (United States)

    Na, Dongsoo; Park, Kichul; Park, Ki-Hwan; Song, Yong-Won

    2017-11-24

    Black phosphorus (BP) has attracted increasing attention due to its unique electrical properties. In addition, the outstanding optical nonlinearity of BP has been demonstrated in various ways. Its functionality as a saturable absorber, in particular, has been validated in demonstrations of passive mode-locked lasers. However, normally, the performance of BP is degraded eventually by both thermal and chemical damage in ambient conditions. The passivation of BP is the critical issue to guarantee a stable performance of the optical devices. We quantitatively characterized the mode-locked lasers operated by BP saturable absorbers with diversified passivation materials such as polydimethylsiloxane (PDMS) or Al 2 O 3 , considering the atomic structure of the materials, and therefore the hydro-permeability of the passivation layers. Unlike the BP layers without passivation, we demonstrated that the Al 2 O 3 -passivated BP layer was protected from the surface oxidation reaction in the long-term, and the PDMS-passivated one had a short-term blocking effect. The quantitative analysis showed that the time-dependent characteristics of the pulsed laser without passivation were changed with respect to the pulse duration, spectral width, and time-bandwidth product displaying 550 fs, 2.8 nm, and 0.406, respectively. With passivation, the changes were limited to <43 fs, <0.3 nm, and <0.012, respectively.

  7. Passivation of black phosphorus saturable absorbers for reliable pulse formation of fiber lasers

    Science.gov (United States)

    Na, Dongsoo; Park, Kichul; Park, Ki-Hwan; Song, Yong-Won

    2017-11-01

    Black phosphorus (BP) has attracted increasing attention due to its unique electrical properties. In addition, the outstanding optical nonlinearity of BP has been demonstrated in various ways. Its functionality as a saturable absorber, in particular, has been validated in demonstrations of passive mode-locked lasers. However, normally, the performance of BP is degraded eventually by both thermal and chemical damage in ambient conditions. The passivation of BP is the critical issue to guarantee a stable performance of the optical devices. We quantitatively characterized the mode-locked lasers operated by BP saturable absorbers with diversified passivation materials such as polydimethylsiloxane (PDMS) or Al2O3, considering the atomic structure of the materials, and therefore the hydro-permeability of the passivation layers. Unlike the BP layers without passivation, we demonstrated that the Al2O3-passivated BP layer was protected from the surface oxidation reaction in the long-term, and the PDMS-passivated one had a short-term blocking effect. The quantitative analysis showed that the time-dependent characteristics of the pulsed laser without passivation were changed with respect to the pulse duration, spectral width, and time-bandwidth product displaying 550 fs, 2.8 nm, and 0.406, respectively. With passivation, the changes were limited to <43 fs, <0.3 nm, and <0.012, respectively.

  8. Information barriers

    International Nuclear Information System (INIS)

    Fuller, J.L.; Wolford, J.

    2001-01-01

    Full text: An information barrier (IB) consists of procedures and technology that prevent the release of sensitive information during a joint inspection of a sensitive nuclear item, and provides confidence that the measurement system into which it has been integrated functions exactly as designed and constructed. Work in the U.S. on radiation detection system information barriers dates back at least to 1990, even though the terminology is more recent. In January 1999 the Joint DoD-DOE Information Barrier Working Group was formed in the United States to help coordinate technical efforts related to information barrier R and D. This paper presents an overview of the efforts of this group, by its Chairs, as well as recommendations for further information barrier R and D. Progress on the demonstration of monitoring systems containing IBs is also provided. From the U.S. perspective, the basic, top-level functional requirements for the information barrier portion of an integrated radiation signature-information barrier inspection system are twofold: The host must be assured that his classified information is protected from disclosure to the inspecting party; and The inspecting party must be confident that the integrated inspection system measures, processes, and presents the radiation-signature-based measurement conclusion in an accurate and reproducible manner. It is the position of the United States that in the absence of any agreement to share classified nuclear weapons design information in the conduct of an inspection regime, the requirement to protect host country classified warhead design information is paramount and admits no tradeoff versus the confidence provided to the inspecting party in the accuracy and reproducibility of the measurements. The U.S. has reached an internal consensus on several critical design elements that define a general standard for radiation signature information barrier design. These criteria have stood the test of time under intense

  9. Compact rock material gas permeability properties

    Energy Technology Data Exchange (ETDEWEB)

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

    2014-09-15

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

  10. Gas and Water Permeability of Concrete

    Energy Technology Data Exchange (ETDEWEB)

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

    2012-11-01

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

  11. Permeability During Magma Expansion and Compaction

    Science.gov (United States)

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

    2017-12-01

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

  12. Towards the rational design of novel drugs based on solubility, partitioning/distribution, biomimetic permeability and biological activity exemplified by 1,2,4-thiadiazole derivatives

    DEFF Research Database (Denmark)

    Volkova, T. V.; Terekhova, I. V.; Silyukov, O. I.

    2017-01-01

    -octanol/buffer (pH 7.4) and 1-hexane/buffer (pH 7.4) immiscible phases as model systems imitating the gastrointestinal tract epithelium and the blood-brain barrier were determined. Permeation experiments the new Permeapad™ barrier using Franz diffusion cells were conducted and the apparent permeability...

  13. Floating barrier

    Energy Technology Data Exchange (ETDEWEB)

    1968-05-06

    This floating barrier consists of relatively long elements which can be connected to form a practically continuous assembly. Each element consists of an inflatable tube with an apron of certain height, made of impregnated fabric which is resistant to ocean water and also to hydrocarbons. Means for connecting one element to the following one, and means for attaching ballast to the apron are also provided.

  14. Columbia County Habitat for Humanity Passive Townhomes

    Energy Technology Data Exchange (ETDEWEB)

    Dentz, Jordan [The Advanced Residential Integrated Energy Solutions Collaborative, New York, NY (United States); Alaigh, Kunal [The Advanced Residential Integrated Energy Solutions Collaborative, New York, NY (United States); Dadia, Devanshi [The Advanced Residential Integrated Energy Solutions Collaborative, New York, NY (United States)

    2016-03-18

    Columbia County (New York) Habitat for Humanity built a pair of townhomes to Passive House criteria with the purpose of exploring approaches for achieving Passive House performance and to eventually develop a prototype design for future projects. The project utilized a 2x6 frame wall with a structural insulated panel curtain wall and a ventilated attic over a sealed OSB ceiling air barrier. Mechanical systems include a single head, wall mounted ductless mini-split heat pump in each unit and a heat recovery ventilator. Costs were $26,000 per unit higher for Passive House construction compared with the same home built to ENERGY STAR version 3 specifications, representing about 18% of total construction cost. This report discusses the cost components, energy modeling results and lessons from construction. Two alternative ventilation systems are analyzed: a central system; and, a point-source system with small through-wall units distributed throughout the house. The report includes a design and cost analysis of these two approaches.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2000-07-01

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

  16. Passive solar heating

    Energy Technology Data Exchange (ETDEWEB)

    Wiberg, K

    1981-11-10

    The present work treats the possibilities for heating according to the passive solar heating method. Problems of 'spatial organization in an energy-saving society' are distinguished from among other social problems. The final delimination of the actual problems under investigation consists of the use of passive solar heating and especially the 'consequences of such solar heating exploitation upon the form and structures' of planning and construction. In the concluding chapter an applied example shows how this method can be used in designing an urban area and what are its limitations. The results indicate the possibilities and difficulties in attempting to transfer this ideal and general method into models and directives for form and structure from which examples of the actual possibilities in practical planning can be given.

  17. Vertical barriers with increased sorption capacities

    International Nuclear Information System (INIS)

    Bradl, H.B.

    1997-01-01

    Vertical barriers are commonly used for the containment of contaminated areas. Due to the very small permeability of the barrier material which is usually in the order of magnitude of 10-10 m/s or less the advective contaminant transport can be more or less neglected. Nevertheless, there will always be a diffusive contaminant transport through the barrier which is caused by the concentration gradient. Investigations have been made to increase the sorption capacity of the barrier material by adding substances such as organoclays, zeolites, inorganic oxides and fly ashes. The contaminants taken into account where heavy metals (Pb) and for organic contaminants Toluole and Phenantrene. The paper presents results of model calculations and experiments. As a result, barrier materials can be designed 'tailor-made' depending on the individual contaminant range of each site (e.g. landfills, gasworks etc.). The parameters relevant for construction such as rheological properties, compressive strength and permeability are not affected by the addition of the sorbents

  18. Qademah Fault Passive Data

    KAUST Repository

    Hanafy, Sherif M.

    2014-01-01

    OBJECTIVE: In this field trip we collect passive data to 1. Convert passive to surface waves 2. Locate Qademah fault using surface wave migration INTRODUCTION: In this field trip we collected passive data for several days. This data will be used to find the surface waves using interferometry and then compared to active-source seismic data collected at the same location. A total of 288 receivers are used. A 3D layout with 5 m inline intervals and 10 m cross line intervals is used, where we used 12 lines with 24 receivers at each line. You will need to download the file (rec_times.mat), it contains important information about 1. Field record no 2. Record day 3. Record month 4. Record hour 5. Record minute 6. Record second 7. Record length P.S. 1. All files are converted from original format (SEG-2) to matlab format P.S. 2. Overlaps between records (10 to 1.5 sec.) are already removed from these files

  19. Concept research on general passive system

    International Nuclear Information System (INIS)

    Han Xu; Yang Yanhua; Zheng Mingguang

    2009-01-01

    This paper summarized the current passive techniques used in nuclear power plants. Through classification and analysis, the functional characteristics and inherent identification of passive systems were elucidated. By improving and extending the concept of passive system, the general passive concept was proposed, and space and time relativity was discussed and assumption of general passive system were illustrated. The function of idealized general passive system is equivalent with the current passive system, but the design of idealized general passive system is more flexible. (authors)

  20. Possible links between intestinal permeablity and food processing: a potential therapeutic niche for glutamine

    Directory of Open Access Journals (Sweden)

    Jean Robert Rapin

    2010-01-01

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

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

    Science.gov (United States)

    Rapin, Jean Robert; Wiernsperger, Nicolas

    2010-01-01

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

  2. Gas and water permeability of concrete for reactor buildings--prototype scale specimens

    International Nuclear Information System (INIS)

    Mills, R.H.

    1987-02-01

    The permeability testing was performed on four concrete cylinders, 0.25 m in diameter and 2 m long, modelling the wall-thickness of reactor containment structures on the prototype scale. Tests were performed on the cylinders before and after artificial induction of longitudinal cracks, intented to model defects developing after some period of adverse service conditions. Permeability increased greatly with the introduction of longitudinal cracks in the concrete, and was also affected by moisture content and casting direction. The influence of reinforcing steel could not be resolved within the bounds of experimental variability. Ultrasound measurements were taken on each cylinder before and after cracking, and a correlation between increased permeability and lowered Ultrasonic Pulse Velocity was observed. Ultrasonic Pulse Velocity measurements thus show promise as a means of continuous monitoring of the integrity of the concrete barrier in service

  3. Barrier abnormalities and keratinocyte-derived cytokine cascade after cessation of long-term topical glucocorticosteroid on hairless mouse skin

    Directory of Open Access Journals (Sweden)

    Tzu-Kai Lin

    2015-06-01

    Conclusion: An epidermis-derived cytokine cascade was observed following TCS-induced barrier disruption, which is similar to that from permeability barrier insults by acetone or tape stripping. The study suggests that concurrent application of skin care products during TCS treatment improves barrier homeostasis, and should become a standard practice to alleviate TCS-induced WD.

  4. Characterization of a novel brain barrier ex vivo insect-based P-glycoprotein screening model

    DEFF Research Database (Denmark)

    Andersson, O.; Badisco, L.; Hansen, A. H.

    2014-01-01

    In earlier studies insects were proposed as suitable models for vertebrate blood–brain barrier (BBB) permeability prediction and useful in early drug discovery. Here we provide transcriptome and functional data demonstrating the presence of a P-glycoprotein (Pgp) efflux transporter in the brain b...... has the potential to act as a robust and convenient model for assessing BBB permeability in early drug discovery.......In earlier studies insects were proposed as suitable models for vertebrate blood–brain barrier (BBB) permeability prediction and useful in early drug discovery. Here we provide transcriptome and functional data demonstrating the presence of a P-glycoprotein (Pgp) efflux transporter in the brain...

  5. Permeability Tests on Silkeborg Sand No. 0000

    DEFF Research Database (Denmark)

    Lund, Willy; Jakobsen, Kim Parsberg

    on the characteristics of the soil matrix, the permeability is determined for different void ratios. All tests are performed on reconstituted specimens of Silkeborg Sand No. 0000. The permeability is determined by use of a falling head apparatus. The apparatus, test procedures and the analysis method are described......The flow through porous media plays an important role in various engineering disciplines, as for example in ground water hydrology and soil mechanics. In the present study the permeability is determined for a fine, saturated sand. As the flow through a porous media strongly depends...

  6. Permeability Tests on Eastern Scheldt Sand

    DEFF Research Database (Denmark)

    Jakobsen, Kim Parsberg

    on the characteristics of the soil matrix, the permeability is determined for different void ratios. All tests are performed on reconstituted specimens of Eastern Scheldt Sand. The permeability is determined by use of a falling head apparatus. Finally the test results are briefly summarised and a relationship between......The flow through porous media plays an important role in various engineering disciplines, as for example in ground water hydrology and soil mechanics. In the present study the permeability is determined for a fine, saturated sand. As the flow through a porous media strongly depends...

  7. Smart parking barrier

    KAUST Repository

    Alharbi, Abdulrazaq M.

    2016-01-01

    positioning of the movable parking barrier, and a parking controller configured to initiate movement of the parking barrier, via the barrier drive. The movable parking barrier can be positioned between a first position that restricts access to the parking

  8. Polymer/Silicate Nanocomposites Used to Manufacture Gas Storage Tanks With Reduced Permeability

    Science.gov (United States)

    Campbell, Sandi G.; Johnston, Chris

    2004-01-01

    Over the past decade, there has been considerable research in the area of polymer-layered silicate nanocomposites. This research has shown that the dispersion of small amounts of an organically modified layered silicate improves the polymer strength, modulus, thermal stability, and barrier properties. There have been several reports on the dispersion of layered silicates in an epoxy matrix. Potential enhancements to the barrier properties of epoxy/silicate nanocomposites make this material attractive for low permeability tankage. Polymer matrix composites (PMCs) have several advantages for cryogenic storage tanks. They are lightweight, strong, and stiff; therefore, a smaller fraction of a vehicle's potential payload capacity is used for propellant storage. Unfortunately, the resins typically used to make PMC tanks have higher gas permeability than metals. This can lead to hydrogen loss through the body of the tank instead of just at welds and fittings. One approach to eliminate this problem is to build composite tanks with thin metal liners. However, although these tanks provide good permeability performance, they suffer from a substantial mismatch in the coefficient of thermal expansion, which can lead to failure of the bond between the liner and the body of the tank. Both problems could be addressed with polymersilicate nanocomposites, which exhibit reduced hydrogen permeability, making them potential candidates for linerless PMC tanks. Through collaboration with Northrop Grumman and Michigan State University, nanocomposite test tanks were manufactured for the NASA Glenn Research Center, and the helium permeability was measured. An organically modified silicate was prepared at Michigan State University and dispersed in an epoxy matrix (EPON 826/JeffamineD230). The epoxy/silicate nanocomposites contained either 0 or 5 wt% of the organically modified silicate. The tanks were made by filament winding carbon fibers with the nanocomposite resin. Helium permeability

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

    Science.gov (United States)

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

    2017-06-06

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

  10. Permeability, transport, and metabolism of solutes in Caco-2 cell monolayers: a theoretical study.

    Science.gov (United States)

    Sun, Huadong; Pang, K Sandy

    2008-01-01

    We explored the properties of a catenary model that includes the basolateral (B), apical (A), and cellular compartments via simulations under linear and nonlinear conditions to understand the asymmetric observations arising from transporters, enzymes, and permeability in Caco-2 cells. The efflux ratio (EfR; P(app,B-->A)/P(app,A-->B)), obtained from the effective permeability from the A-->B and B-->A direction under linear conditions, was unity for passively permeable drugs whose transport does not involve transporters; the value was unaffected by cellular binding or metabolism, but increased with apical efflux. Metabolism was asymmetric, showing lesser metabolite accrual for the B-->A than A-->B direction because of inherent differences in the volumes for A and B. Moreover, the net flux (total - passive permeation) due to saturable apical efflux, absorption, or metabolism showed nonconformity to simple Michaelis-Menten kinetics against C(D,0), the loading donor concentration. EfR values differed with saturable apical efflux and metabolism (>1), as well as apical absorption (EfRs transport and metabolic data in Caco-2 cells.

  11. Transport phenomena in sharply contrasting media with a diffusion barrier

    International Nuclear Information System (INIS)

    Dvoretskaya, O A; Kondratenko, P S

    2011-01-01

    Using the advection–diffusion equation, we analytically study contaminant transport in a sharply contrasting medium with a diffusion barrier due to localization of a contaminant source in a low-permeability medium. Anomalous diffusion behavior and a crossover between different transport regimes are observed. The diffusion barrier results in exponential attenuation of the source power, retardation of the contaminant plume growth and modification of the concentration distribution at large distances. (paper)

  12. Electron grafted barrier coatings for packaging film modification

    International Nuclear Information System (INIS)

    Rangwalla, I.J.; Nablo, S.V.

    1993-01-01

    The O 2 barrier performance of organosilane films, coated, dried and electron beam grafted to polyolefin film has been studied. Excellent anti-scalping properties based upon limonene (dipentene) transmission measurements have also been observed. Results are also reported on O 2 permeability reduction when the process is applied to common barrier polymers such as EVOH and acrylonitrile. Experience with its in-line application on LDPE is discussed. (author)

  13. Borehole stoneley waves and permeability: Laboratory results

    International Nuclear Information System (INIS)

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

    1987-01-01

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

  14. Dentin Permeability of Carious Primary Teeth

    African Journals Online (AJOL)

    primary dental pulp make it difficult to determine which modality offers the best ... The most common pathology of the dentine is dental caries. ... to evaluate dentine permeability is to calculate its hydraulic conductance (Lp) using fluid filtration ...

  15. Permeability of gypsum samples dehydrated in air

    Science.gov (United States)

    Milsch, Harald; Priegnitz, Mike; Blöcher, Guido

    2011-09-01

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

  16. Permeability After Impact Testing of Composite Laminates

    Science.gov (United States)

    Nettles, Alan T.

    2003-01-01

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

  17. Passive Power Filters

    CERN Document Server

    Künzi, R.

    2015-06-15

    Power converters require passive low-pass filters which are capable of reducing voltage ripples effectively. In contrast to signal filters, the components of power filters must carry large currents or withstand large voltages, respectively. In this paper, three different suitable filter struc tures for d.c./d.c. power converters with inductive load are introduced. The formulas needed to calculate the filter components are derived step by step and practical examples are given. The behaviour of the three discussed filters is compared by means of the examples. P ractical aspects for the realization of power filters are also discussed.

  18. 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.

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

    International Nuclear Information System (INIS)

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

    2002-01-01

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

  20. Surface sedimentation at permeable pavement systems

    DEFF Research Database (Denmark)

    Støvring, Jan; Dam, Torben; Jensen, Marina Bergen

    2018-01-01

    Newly installed permeable pavement (PP) systems provide high surface infiltration capacity, but the accumulation of sediments causes a decrease in capacity over time, eventually leading to surface clogging. With the aim of investigating local sedimentation processes and the importance of restorat......Newly installed permeable pavement (PP) systems provide high surface infiltration capacity, but the accumulation of sediments causes a decrease in capacity over time, eventually leading to surface clogging. With the aim of investigating local sedimentation processes and the importance...

  1. Negative permeability from random particle composites

    Energy Technology Data Exchange (ETDEWEB)

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

    2017-04-15

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

  2. Transformable ferroelectric control of dynamic magnetic permeability

    Science.gov (United States)

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

    2018-02-01

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

  3. Defining clogging potential for permeable concrete.

    Science.gov (United States)

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

    2018-08-15

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

  4. Accurate control testing for clay liner permeability

    Energy Technology Data Exchange (ETDEWEB)

    Mitchell, R J

    1991-08-01

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

  5. Cell permeability beyond the rule of 5.

    Science.gov (United States)

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

    2016-06-01

    Drug discovery for difficult targets that have large and flat binding sites is often better suited to compounds beyond the "rule of 5" (bRo5). However, such compounds carry higher pharmacokinetic risks, such as low solubility and permeability, and increased efflux and metabolism. Interestingly, recent drug approvals and studies suggest that cell permeable and orally bioavailable drugs can be discovered far into bRo5 space. Tactics such as reduction or shielding of polarity by N-methylation, bulky side chains and intramolecular hydrogen bonds may be used to increase cell permeability in this space, but often results in decreased solubility. Conformationally flexible compounds can, however, combine high permeability and solubility, properties that are keys for cell permeability and intestinal absorption. Recent developments in computational conformational analysis will aid design of such compounds and hence prediction of cell permeability. Transporter mediated efflux occurs for most investigated drugs in bRo5 space, however it is commonly overcome by high local intestinal concentrations on oral administration. In contrast, there is little data to support significant impact of transporter-mediated intestinal absorption in bRo5 space. Current knowledge of compound properties that govern transporter effects of bRo5 drugs is limited and requires further fundamental and comprehensive studies. Copyright © 2016 Elsevier B.V. All rights reserved.

  6. Expansion of passive safety function

    International Nuclear Information System (INIS)

    Inai, Nobuhiko; Nei, Hiromichi; Kumada, Toshiaki.

    1995-01-01

    Expansion of the use of passive safety functions is proposed. Two notions are presented. One is that, in the design of passive safety nuclear reactors where aversion of active components is stressed, some active components are purposely introduced, by which a system is built in such a way that it behaves in an apparently passive manner. The second notion is that, instead of using a passive safety function alone, a passive safety function is combined with some active components, relating the passivity in the safety function with enhanced controllability in normal operation. The nondormant system which the authors propose is one example of the first notion. This is a system in which a standby safety system is a portion of the normal operation system. An interpretation of the nondormant system via synergetics is made. As an example of the second notion, a PIUS density lock aided with active components is proposed and is discussed

  7. Hydrostatic and shear consolidation tests with permeability measurements on Waste Isolation Pilot Plant crushed salt

    International Nuclear Information System (INIS)

    Brodsky, N.S.

    1994-03-01

    Crushed natural rock salt is a primary candidate for use as backfill and barrier material at the Waste Isolation Pilot Plant (WIPP) and therefore Sandia National Laboratories (SNL) has been pursuing a laboratory program designed to quantify its consolidation properties and permeability. Variables that influence consolidation rate that have been examined include stress state and moisture content. The experimental results presented in this report complement existing studies and work in progress conducted by SNL. The experiments described in this report were designed to (1) measure permeabilities of consolidated specimens of crushed salt, (2) determine the influence of brine saturation on consolidation under hydrostatic loads, and 3) measure the effects of small applied shear stresses on consolidation properties. The laboratory effort consisted of 18 individual tests: three permeability tests conducted on specimens that had been consolidated at Sandia, six hydrostatic consolidation and permeability tests conducted on specimens of brine-saturated crushed WIPP salt, and nine shear consolidation and permeability tests performed on crushed WIPP salt specimens containing 3 percent brine by weight. For hydrostatic consolidation tests, pressures ranged from 1.72 MPa to 6.90 MPa. For the shear consolidation tests, confining pressures were between 3.45 MPa and 6.90 MPa and applied axial stress differences were between 0.69 and 4.14 MPa. All tests were run under drained conditions at 25 degrees C

  8. 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.

  9. Multiple Targets for Novel Therapy of FSGS Associated with Circulating Permeability Factor

    Directory of Open Access Journals (Sweden)

    Virginia J. Savin

    2017-01-01

    Full Text Available A plasma component is responsible for altered glomerular permeability in patients with focal segmental glomerulosclerosis. Evidence includes recurrence after renal transplantation, remission after plasmapheresis, proteinuria in infants of affected mothers, transfer of proteinuria to experimental animals, and impaired glomerular permeability after exposure to patient plasma. Therapy may include decreasing synthesis of the injurious agent, removing or blocking its interaction with cells, or blocking signaling or enhancing cell defenses to restore the permeability barrier and prevent progression. Agents that may prevent the synthesis of the permeability factor include cytotoxic agents or aggressive chemotherapy. Extracorporeal therapies include plasmapheresis, immunoadsorption with protein A or anti-immunoglobulin, or lipopheresis. Oral or intravenous galactose also decreases Palb activity. Studies of glomeruli have shown that several strategies prevent the action of FSGS sera. These include blocking receptor-ligand interactions, modulating cell reactions using indomethacin or eicosanoids 20-HETE or 8,9-EET, and enhancing cytoskeleton and protein interactions using calcineurin inhibitors, glucocorticoids, or rituximab. We have identified cardiotrophin-like cytokine factor 1 (CLCF-1 as a candidate for the permeability factor. Therapies specific to CLCF-1 include potential use of cytokine receptor-like factor (CRLF-1 and inhibition of Janus kinase 2. Combined therapy using multiple modalities offers therapy to reverse proteinuria and prevent scarring.

  10. Ascorbic acid attenuates endothelial permeability triggered by cell-free hemoglobin.

    Science.gov (United States)

    Kuck, Jamie L; Bastarache, Julie A; Shaver, Ciara M; Fessel, Joshua P; Dikalov, Sergey I; May, James M; Ware, Lorraine B

    2018-01-01

    Increased endothelial permeability is central to shock and organ dysfunction in sepsis but therapeutics targeted to known mediators of increased endothelial permeability have been unsuccessful in patient studies. We previously reported that cell-free hemoglobin (CFH) is elevated in the majority of patients with sepsis and is associated with organ dysfunction, poor clinical outcomes and elevated markers of oxidant injury. Others have shown that Vitamin C (ascorbate) may have endothelial protective effects in sepsis. In this study, we tested the hypothesis that high levels of CFH, as seen in the circulation of patients with sepsis, disrupt endothelial barrier integrity. Human umbilical vein endothelial cells (HUVEC) were grown to confluence and treated with CFH with or without ascorbate. Monolayer permeability was measured by Electric Cell-substrate Impedance Sensing (ECIS) or transfer of 14 C-inulin. Viability was measured by trypan blue exclusion. Intracellular ascorbate was measured by HPLC. CFH increased permeability in a dose- and time-dependent manner with 1 mg/ml of CFH increasing inulin transfer by 50% without affecting cell viability. CFH (1 mg/ml) also caused a dramatic reduction in intracellular ascorbate in the same time frame (1.4 mM without CFH, 0.23 mM 18 h after 1 mg/ml CFH, p < 0.05). Pre-treatment of HUVECs with ascorbate attenuated CFH induced permeability. CFH increases endothelial permeability in part through depletion of intracellular ascorbate. Supplementation of ascorbate can attenuate increases in permeability mediated by CFH suggesting a possible therapeutic approach in sepsis. Copyright © 2017 Elsevier Inc. All rights reserved.

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

    Science.gov (United States)

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

    2013-03-30

    Fully permeable pavement is gradually gaining support as an alternative best management practice (BMP) for stormwater runoff management. As the use of these pavements increases, a definitive test method is needed to measure hydraulic performance and to evaluate clogging, both for performance studies and for assessment of permeability for construction quality assurance and maintenance needs assessment. Two of the most commonly used permeability measurement tests for porous asphalt and pervious concrete are the National Center for Asphalt Technology (NCAT) permeameter and ASTM C1701, respectively. This study was undertaken to compare measured values for both methods in the field on a variety of permeable pavements used in current practice. The field measurements were performed using six experimental section designs with different permeable pavement surface types including pervious concrete, porous asphalt and permeable interlocking concrete pavers. Multiple measurements were performed at five locations on each pavement test section. The results showed that: (i) silicone gel is a superior sealing material to prevent water leakage compared with conventional plumbing putty; (ii) both methods (NCAT and ASTM) can effectively be used to measure the permeability of all pavement types and the surface material type will not impact the measurement precision; (iii) the permeability values measured with the ASTM method were 50-90% (75% on average) lower than those measured with the NCAT method; (iv) the larger permeameter cylinder diameter used in the ASTM method improved the reliability and reduced the variability of the measured permeability. Copyright © 2013 Elsevier Ltd. All rights reserved.

  12. Passive cooling containment study

    International Nuclear Information System (INIS)

    Shin, J.J.; Iotti, R.C.; Wright, R.F.

    1993-01-01

    Pressure and temperature transients of nuclear reactor containment following postulated loss of coolant accident with a coincident station blackout due to total loss of all alternating current power are studied analytically and experimentally for the full scale NPR (New Production Reactor). All the reactor and containment cooling under this condition would rely on the passive cooling system which removes reactor decay heat and provides emergency core and containment cooling. Containment passive cooling for this study takes place in the annulus between containment steel shell and concrete shield building by natural convection air flow and thermal radiation. Various heat transfer coefficients inside annular air space were investigated by running the modified CONTEMPT code CONTEMPT-NPR. In order to verify proper heat transfer coefficient, temperature, heat flux, and velocity profiles were measured inside annular air space of the test facility which is a 24 foot (7.3m) high, steam heated inner cylinder of three foot (.91m) diameter and five and half foot (1.7m) diameter outer cylinder. Comparison of CONTEMPT-NPR and WGOTHIC was done for reduced scale NPR

  13. Fly ash carbon passivation

    Science.gov (United States)

    La Count, Robert B; Baltrus, John P; Kern, Douglas G

    2013-05-14

    A thermal method to passivate the carbon and/or other components in fly ash significantly decreases adsorption. The passivated carbon remains in the fly ash. Heating the fly ash to about 500 and 800 degrees C. under inert gas conditions sharply decreases the amount of surfactant adsorbed by the fly ash recovered after thermal treatment despite the fact that the carbon content remains in the fly ash. Using oxygen and inert gas mixtures, the present invention shows that a thermal treatment to about 500 degrees C. also sharply decreases the surfactant adsorption of the recovered fly ash even though most of the carbon remains intact. Also, thermal treatment to about 800 degrees C. under these same oxidative conditions shows a sharp decrease in surfactant adsorption of the recovered fly ash due to the fact that the carbon has been removed. This experiment simulates the various "carbon burnout" methods and is not a claim in this method. The present invention provides a thermal method of deactivating high carbon fly ash toward adsorption of AEAs while retaining the fly ash carbon. The fly ash can be used, for example, as a partial Portland cement replacement in air-entrained concrete, in conductive and other concretes, and for other applications.

  14. Effects of Electromagnetic Fields on the Blood Brain Barrier

    National Research Council Canada - National Science Library

    Persson, Rolf

    2000-01-01

    ...) in the 91 5-2450 MHz range on the permeability of the blood brain barrier (BBB) in rats. Male and female Fischer rats were exposed to continuous wave or pulse-modulated EMF, with different pulse powers and times up to 960 minutes...

  15. Surface Passivation in Empirical Tight Binding

    OpenAIRE

    He, Yu; Tan, Yaohua; Jiang, Zhengping; Povolotskyi, Michael; Klimeck, Gerhard; Kubis, Tillmann

    2015-01-01

    Empirical Tight Binding (TB) methods are widely used in atomistic device simulations. Existing TB methods to passivate dangling bonds fall into two categories: 1) Method that explicitly includes passivation atoms is limited to passivation with atoms and small molecules only. 2) Method that implicitly incorporates passivation does not distinguish passivation atom types. This work introduces an implicit passivation method that is applicable to any passivation scenario with appropriate parameter...

  16. Passive-solar construction handbook

    Energy Technology Data Exchange (ETDEWEB)

    Levy, E.; Evans, D.; Gardstein, C.

    1981-02-01

    Many of the basic elements of passive solar design are reviewed. Passive solar construction is covered according to system type, each system type discussion including a general discussion of the important design and construction issues which apply to the particular system and case studies illustrating designed and built examples of the system type. The three basic types of passive solar systems discussed are direct gain, thermal storage wall, and attached sunspace. Thermal performance and construction information is presented for typical materials used in passive solar collector components, storage components, and control components. Appended are an overview of analysis methods and a technique for estimating performance. (LEW)

  17. Hydrogen sulfide metabolism regulates endothelial solute barrier function

    Directory of Open Access Journals (Sweden)

    Shuai Yuan

    2016-10-01

    Full Text Available Hydrogen sulfide (H2S is an important gaseous signaling molecule in the cardiovascular system. In addition to free H2S, H2S can be oxidized to polysulfide which can be biologically active. Since the impact of H2S on endothelial solute barrier function is not known, we sought to determine whether H2S and its various metabolites affect endothelial permeability. In vitro permeability was evaluated using albumin flux and transendothelial electrical resistance. Different H2S donors were used to examine the effects of exogenous H2S. To evaluate the role of endogenous H2S, mouse aortic endothelial cells (MAECs were isolated from wild type mice and mice lacking cystathionine γ-lyase (CSE, a predominant source of H2S in endothelial cells. In vivo permeability was evaluated using the Miles assay. We observed that polysulfide donors induced rapid albumin flux across endothelium. Comparatively, free sulfide donors increased permeability only with higher concentrations and at later time points. Increased solute permeability was associated with disruption of endothelial junction proteins claudin 5 and VE-cadherin, along with enhanced actin stress fiber formation. Importantly, sulfide donors that increase permeability elicited a preferential increase in polysulfide levels within endothelium. Similarly, CSE deficient MAECs showed enhanced solute barrier function along with reduced endogenous bound sulfane sulfur. CSE siRNA knockdown also enhanced endothelial junction structures with increased claudin 5 protein expression. In vivo, CSE genetic deficiency significantly blunted VEGF induced hyperpermeability revealing an important role of the enzyme for barrier function. In summary, endothelial solute permeability is critically regulated via exogenous and endogenous sulfide bioavailability with a prominent role of polysulfides.

  18. The use of tracers in the study of the ionic permeability of the nerve

    International Nuclear Information System (INIS)

    Guinnebault, M.

    1961-01-01

    The use of the radioactive tracers 24 Na and 42 K, and the electrophysiological fine study carried out on the plant Cephalopods nervous cells have made it possible, during ten years, to study the relationships between the electrical phenomena observed during the propagation of the nervous impulse and the ionic movements which occur at the cell membrane between the intra- and extra-cellular media. In the state of rest, the nerve fibres present a certain permeability towards sodium and potassium, a permeability which allows the renewal, from the extra-cellular medium, of the cations contained in the cytoplasm. At the moment of the passage of the nervous impulse, it is possible to demonstrate a temporary increase in the permeability towards the sodium which causes the entry of Na + ions into the nerve fibre, whilst, a few milliseconds later, the increase in the potassium permeability causes the departure of an equivalent quantity of K + ions. A recovery phase follows the passage of the nervous impulse, during which the original ionic conditions are re-established. If the potassium movements can be considered as passive, the expulsion of Na + requires, on the part of the cell, the use of a part of the metabolic energy. (author) [fr

  19. Controlling DC permeability in cast steels

    International Nuclear Information System (INIS)

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

    2017-01-01

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

  20. Controlling DC permeability in cast steels

    Energy Technology Data Exchange (ETDEWEB)

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

    2017-05-01

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

  1. Modulating the skin barrier function by DMSO: molecular dynamics simulations of hydrophilic and hydrophobic transmembrane pores

    NARCIS (Netherlands)

    den Otter, Wouter K.; Notman, R.; Anwar, J.; Noro, M.G.; Briels, Willem J.

    2008-01-01

    The dense lipid bilayers at the outer surface of the skin represent the primary barrier to molecules penetrating the human skin. One approach to overcome this barrier, with promising applications in administering medicinal drugs to the body, is to employ chemical permeability enhancers. How these

  2. Assessment of canine intestinal permeability, using 51Cr-labeled ethylenediaminetetraacetate

    International Nuclear Information System (INIS)

    Hall, E.J.; Batt, R.M.; Brown, A.

    1989-01-01

    The 51 Cr-labeled EDTA was validated as a suitable permeability probe in dogs for measurement of passive, unmediated diffusion across intestinal mucosa via intercellular pathways. The 51 Cr-labeled EDTA was stable in aqueous solution and did not bind to biologic tissue and fluids. After incubation of 51 Cr-labeled EDTA in isolated jejunal loops, analytic subcellular fractionation of jejunal mucosa on reorientating sucrose-density gradients was performed, and no association of 51 Cr-labeled EDTA with particulate intracellular organelles was detected. Intravenously administered 51 Cr-labeled EDTA was rapidly and completely excreted in urine. Intestinal permeability to 51 Cr-labeled EDTA after oral administration was assessed in healthy dogs. The percentage of the administered dose of 51 Cr-labeled EDTA excreted in the urine in 24 hours ranged from 2.3 to 17.6% (median, 13%)

  3. Mobilitet, barrierer & muligheder

    DEFF Research Database (Denmark)

    Petersen, Mimi

    2011-01-01

    stereotypering. På den ene side peger udsagn fra de unge drenge på en oplevelse af at blive kriminaliseret i kraft af deres køn (det maskuline kombineret med at have en anden hudfarve). Og de unge piger oplever, at de udover at blive kategoriseret som ”indvandrere” også bliver kategoriseret som passive, umyndige...... som en vej ud af irakiske Kurdistan, men ikke tilbage til Danmark. Drengene fra familier med bedre økonomiske ressourcer giver udtryk for, ønske om at rejse til andre lande. På grund af begrænsede sproglige kompetencer oplever hovedparten af de unge (både i Danmark og i irakiske Kurdistan) barrierer i...... har planer for at flytte fra Kurdistan. De har dansk statsborgerskab, men de vil ikke tilbage til Danmark. I de fortællinger, som afhandlingen bygger på, er det tydeligt at samspillet mellem flere sociale dimensioner, spiller ind på de unges selvforståelse, tilhørsforhold, erfaringer og deres valg af...

  4. Constructing bottom barriers with met grouting

    International Nuclear Information System (INIS)

    Shibazaki, M.; Yoshida, H.

    1997-01-01

    Installing a bottom barrier using conventional high pressure jetting technology and ensuring barrier continuity is challenging. This paper describes technology that has been developed and demonstrated for the emplacement of bottom barriers using pressures and flow rates above the conventional high pressure jetting parameters. The innovation capable of creating an improved body exceeding 5 meters in diameter has resulted in the satisfying connection and adherence between the treated columns. Besides, the interfaces among the improved bodies obtain the same strength and permeability lower than 1 x 10 -7 cm/sec as body itself. A wide variety of the thickness and the diameter of the improved mass optimizes the application, and the method is nearing completion. The paper explains an aspect and briefs case histories

  5. Probable variations of a passive safety containment for a 1700 MWe class PWR with passive safety systems

    International Nuclear Information System (INIS)

    Sato, Takashi; Fujiki, Yasunobu; Oikawa, Hirohide; Ofstun, Richard P.

    2009-01-01

    The paper presents probable variations of a passive safety containment for a PWR. The passive safety containment is named Mark P containment tentatively. It is a pressure suppression type containment for a large scale PWR with a BWR type passive containment cooling system (PCCS). More than 3-day grace period can be achieved even for a 1700 MWe class large scale PWR owing to the PCCS. The containment is a reinforced concrete containment vessel (RCCV). The design pressure of the RCCV can be low owing to the suppression pool (S/P) and no prestressed tendon is necessary. It is a single barrier CV that can withstand a large airplane crash by itself. This simple configuration results in good economy and short construction term. The BWR type passive safety systems also include the Passive Cooling and Depressurization System (PCDS). The PCDS has 3-day grace period for the SBO induced by a giant earthquake and can practically eliminate the residual risk of a giant earthquake beyond the design basis earthquake of Ss. It also has a safety function to automatically depressurize the primary system at accidents such as SGTR and eliminate the need for operator actions. It is a large 1700 MWe passive safety PWR that has more than 3-day grace period for extremely severe natural disasters including a giant earthquake, a mega hurricane, tsunami and so on; no containment failure at a SA establishing a no evacuation plant; protection for a large airplane crash with the RCCV single barrier; good economy and short construction term. (author)

  6. Passive magnetic bearing system

    Science.gov (United States)

    Post, Richard F.

    2014-09-02

    An axial stabilizer for the rotor of a magnetic bearing provides external control of stiffness through switching in external inductances. External control also allows the stabilizer to become a part of a passive/active magnetic bearing system that requires no external source of power and no position sensor. Stabilizers for displacements transverse to the axis of rotation are provided that require only a single cylindrical Halbach array in its operation, and thus are especially suited for use in high rotation speed applications, such as flywheel energy storage systems. The elimination of the need of an inner cylindrical array solves the difficult mechanical problem of supplying support against centrifugal forces for the magnets of that array. Compensation is provided for the temperature variation of the strength of the magnetic fields of the permanent magnets in the levitating magnet arrays.

  7. European vehicle passive safety network

    NARCIS (Netherlands)

    Wismans, J.S.H.M.; Janssen, E.G.

    1999-01-01

    The general objective of the European Vehicle Passive Safety Network is to contribute to the reduction of the number of road traffic victims in Europe by passive safety measures. The aim of the road safety policy of the European Commission is to r