• Title, Summary, Keyword: cell permeability

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Mass Transfer and Heat Transfer Characteristics of PEM fuel cell by Permeability of GDL (GDL Permeability에 따른 고분자 전해질 연료전지의 물질전달 및 열전달 특성에 관한 연구)

  • Han, Sang-Seok;Lee, Pil-Hyong;Park, Chang-Soo;Lee, Jae-Young;Hwang, Sang-Soon
    • Proceedings of the KSME Conference
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    • pp.2822-2827
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    • 2008
  • Among the main components of PEM fuel cell, the functions of GDL are to transport reactants from the channel to the catalyst and remove reaction products from the catalyst and transport heat from the catalyst to the channels in the flow filed plate. Permeability of GDL is known to make it possible to enhance the gas transport through GDL, devoting to get better performance. In this paper, three dimensional numerical simulation of the fuel cell by the permeability of GDL is presented by using a FLUENT modified to include the electrochemical behavior. Results show that as permeability is higher than $10^{-12}m^2$, gradients of temperature distribution, oxygen molar concentration and current density distribution in MEA were decreased. Although heat generation was increased as high permeability, MEA's temperature was lower than the low permeability of GDL. This seems because that convection was higher affects in mass and heat transfer process than diffusion as permeability of GDL is increases.

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Asymptotic Expansion Homogenization of Permeability Tensor for Plain Woven Fabrics (평직에 대한 투과율 계수의 균질화)

  • Song, Young-Seok;Youn, Jae-Roun
    • Proceedings of the Korean Society For Composite Materials Conference
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    • pp.134-136
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    • 2005
  • Homogenization method is adopted to predict the permeability tenor for glass fiber plain woven fabrics. Calculating the permeability tensor numerically is an encouraging task because the permeability tensor is a key parameter in resin transfer molding (RTM). Based on multi-scale approach of the homogenization method, the permeability for the micro-unit cell within fiber tow is computed and compared with that obtained from flow analysis for the same micro-unit cell. It is found that they are in good agreement. In order to calculate the permeability tensor of macro-unit cell for the plain woven fabrics, the Stokes and Brinkman equations which describe inter-tow and intra-tow flow respectively are employed as governing equations. The effective permeabilities homogenized by considering intra-tow flow are compared with those obtained experimentally. Control volume finite element method (CVFEM) is used as a numerical method. It is shown that the asymptotic expansion homogenization method is an attractive method to predict the effective permeability for heterogeneous media.

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Monoamine Oxidase Inhibitors Attenuate Cytotoxicity of 1-Methyl-4-phenylpyridinium by Suppressing Mitochondrial Permeability Transition

  • Lee, Chung-Soo
    • The Korean Journal of Physiology and Pharmacology
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    • v.10 no.4
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    • pp.207-212
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    • 2006
  • Mitochondrial permeability transition has been shown to be involved in neuronal cell death. Mitochondrial monoamine oxidase (MAO)-B is considered to play a part in the progress of nigrostriatal cell death. The present study examined the effect of MAO inhibitors against the toxicity of 1-methyl-4-phenylpyridinium $(MPP^+)$ in relation to the mitochondrial permeability transition. Chlorgyline (a selective inhibitor of MAO-A), deprenyl (a selective inhibitor of MAO-B) and tranylcypromine (nonselective inhibitor of MAO) all prevented cell viability loss, cytochrome c release, caspase-3 activation, formation of reactive oxygen species and depletion of GSH in differentiated PC12 cells treated with $500\;{\mu}M$$MPP^+$. The MAO inhibitors at $10\;{\mu}M$ revealed a maximal inhibitory effect and beyond this concentration the inhibitory effect declined. On the basis of concentration, the inhibitory potency was tranylcypromine, deprenyl and chlorgyline order. The results suggest that chlorgyline, deprenyl and tranylcypromine attenuate the toxicity of $MPP^+$ against PC12 cells by suppressing the mitochondrial permeability transition that seems to be mediated by oxidative stress.

Evaluating the Regulation of P-glycoprotein by Phytochemicals Using Caco-2 Cell Permeability Assay System

  • Choi, Ran Joo;Kim, Yeong Shik
    • Natural Product Sciences
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    • v.20 no.1
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    • pp.1-6
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    • 2014
  • P-glycoprotein (P-gp) is a permeability glycoprotein also known as multidrug resistance protein 1 (MDR1). P-gp is an ATP-binding cassette (ABC) transporter that pumps various types of drugs out of cells. These transporters reduce the intracellular concentrations of drugs and disturb drug absorption. The Caco-2 cell permeability assay system is an effective in vitro system that predicts the intestinal absorption of drugs and the functions of enzymes and transporters. Rhodamine-123 (R-123) and digoxin are well-known P-gp substrates that have been used to determine the function of P-gp. Efflux of P-gp substrates by P-gp has been routinely evaluated. To date, a number of herbal medicines have been tested with Caco-2 cell permeability assay system to assess bioavailability. There are growing efforts to find phytochemicals that potentially regulate P-gp function. The Caco-2 cell permeability assay system is a primary strategy to search for candidates of P-gp inhibitors. In this mini review, we have summarized the P-gp modulation by herbal extracts, decoctions or single components from natural products using Caco-2 cell permeability assays. Many natural products are known to regulate P-gp and herbal medicines could be used in combination with conventional drugs to enhance bioavailability.

Differential Effect of Harmalol and Deprenyl on Dopamine-Induced Mitochondrial Membrane Permeability Change in PC12 Cells

  • Lee, Chung-Soo
    • Biomolecules & Therapeutics
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    • v.12 no.1
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    • pp.9-18
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    • 2004
  • Opening of the mitochondrial permeability transition pore has been recognized to be involved in cell death. The present study investigated the effect of ${\beta}$-carbolines (harmaline and harmalol) and deprenyl on the dopamine-induced change in the mitochondrial membrane permeability and cell death in differentiated PC12 cells. Cell death due to 250 4{\mu}$M dopamine was inhibited by caspase inhibitors (z-IETD.fmk, z-LEHD.fmk and z-DQMD.fmk) and antioxidants (N-acetylcysteine, ascorbate, superoxide dismutase, catalase and carboxy-PTIO). ${\beta}$-Carbolines prevented the dopamine-induced cell death in PCl2 cells, while deprenyl did not inhibit cell death. ${\beta}$-Carbolines decreased the condensation and fragmentation of nuclei caused by dopamine in PC12 cells. ${\beta}$-Carbolines inhibited the decrease in mitochondrial transmembrane potential, cytochrome c release, formation of reactive oxygen species and depletion of GSH caused by dopamine in PC12 cells, whereas deprenyl did not decrease dopamine-induced mitochondrial damage. ${\beta}$-Carbolines, deprenyl and antioxidants depressed the formation of nitric oxide and melanin in dopamine-treated PC12 cells. The results suggest that cell death due to dopamine PC12 cells is mediated by caspase-8, -9 and -3. Unlike deprenyl, ${\beta}$-carbolines may attenuate the dopamineinduced cell death in PC12 cells by suppressing change in the mitochondrial membrane permeability through inhibition of the toxic action of reactive oxygen and nitrogen species.

Significance of nonlinear permeability in the coupled-numerical analysis of tunnelling

  • Kim, Kang-Hyun;Kim, Ho-Jong;Jeong, Jae-Ho;Shin, Jong-Ho
    • Geomechanics and Engineering
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    • v.21 no.2
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    • pp.103-109
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    • 2020
  • The inflow rate is of interest in the design of underground structures such as tunnels and buried pipes below the groundwater table. Soil permeability governing the inflow rate significantly affects the hydro-geological behavior of soils but is difficult to estimate due to its wide range of distribution, nonlinearity and anisotropy. Volume changes induced by stress can cause nonlinear stress-strain behavior, resulting in corresponding permeability changes. In this paper, the nonlinearity and anisotropy of permeability are investigated by conducting Rowe cell tests, and a nonlinear permeability model considering anisotropy was proposed. Model modification and parameter evaluation for field application were also addressed. Significance of nonlinear permeability was illustrated by carrying out numerical analysis of a tunnel. It is highlighted that the effect of nonlinear permeability is significant in soils of which volume change is considerable, and particularly appears in the short-term flow behavior.

A Study on the Anisotropic Characteristics of Permeability of a Remolded Decomposed Mudstone Soil in Pohang (재성형된 포항 이암풍화토의 투수에 관한 이방성 연구)

  • Kim, Young-Su;Jung, Sung-Gwan;Kim, Dae-Man;Kwon, Yong-Min
    • Journal of the Korean Geoenvironmental Society
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    • v.4 no.3
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    • pp.5-17
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    • 2003
  • Using Rowe cell for vertical and lateral consolidate test, we concerned characteristics of vertical and lateral consolidation, and permeability on the remolded Decompoed Mudstone Soil in Phoang, and then, compared it with Oedometer test results. Indirect coefficients of permeability were calculated by the results of the coefficient of consolidation that were derived from 9 different kinds of methods. The values of indirect coefficients of permeability derived from ${\sqrt{t}}$ method and hyperbolic method were similar to the results of direct coefficients of permeability with respect to vertical drainage, but, in the case of lateral drainage, for all kinds of methods, the values of indirect coefficients of permeability showed overestimated ones. With vertical and lateral direct coefficient of permeability, by investigating the anisotropic effect with respect to permeability on Decomposed mudstone soil, we obtained average value, 13, with respect to anisotropic characteristics for all kinds of consolidation loadings.

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Permeabilization of Ochrobactrum anthropi SY509 Cells with Organic Solvents for Whole Cell Biocatalyst

  • Park, Kyung-Oh;Song, Seung-Hoon;Yoo, Young-Je
    • Biotechnology and Bioprocess Engineering:BBE
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    • v.9 no.3
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    • pp.147-150
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    • 2004
  • Permeabilization is known to overcome cell membrane barriers of whole cell biocatalysts. The use of organic solvents is advantageous in terms of cost, simplicity, and efficiency. In this study, Ochrobactrum anthropi SY509 was permeabilized with various organic solvents. Treatment with organic solvents resulted in lower permeability barriers due to falling out lipids of the cell membrane. Therefore, permeabilized cells showed higher enzyme activity with no cell viability. Among various organic solvents, 0.5% (v/v) chloroform was selected as the most efficient permeabilizing reagent. Changes in the cell membrane structure were observe d and the residual amounts of phospholipids of the cell membrane were measured to investigate the mechanism of the improved permeability.

A Study on Character of Consolidation for Radial Drainage of Pohang배s Clay Ground (포항 점토 지반의 수평배수 압밀특성 연구)

  • Lee, Song;Jeon, Je-Sung;Kim, Won-Young
    • Proceedings of the Korean Geotechical Society Conference
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    • pp.685-692
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    • 2000
  • Vertical drain used improvement soft clay is made of not only decreasing construction time but also increasing the ground strength during some decades. As, it is applied to improvement soft clay with vertical drain, it is designed by the result that is caused by oedemeter test ignored anisotropic of the ground related to consolidation conditions. When we are expected consolidation conditions, the most important factors is soil of compaction and water permeability. Above all, anisotropic of the ground permeability show the results which differ between vertical and radial drainage. Recently, We study for radial consolidation coefficient and permeability coefficient that utilized Rowe Cell Consolidation and permeability tester but, it dont use well because of not only a supply lack also difficulty of test. The paper experimented with searching anisotropic of the ground so there are Rowe Cell test, standard consolidation tester and modified standard consolidation test that have pohang's soft clay ground. Therefore, we find anisotropic of the ground and a tester of easy use more than before. We made a comparison test result between the devised tester and Rowe Cell tester, Also, we learned average degree of consolidation for partial penetrating vertical drains. We were found relations as effective stress-void and effective stress-permeability coefficient through those tests.

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Effect of New Herbicides(CGA 82725 & DOWCO 453) on Membrane Permeability in Bean Leaf Tissue (새로운 제초제(除草劑)가 강남콩잎의 세포막(細胞膜) 투과성(透過性)에 미치는 영향(影響))

  • Kim, Jae-Cheol
    • Korean Journal of Weed Science
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    • v.5 no.1
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    • pp.85-88
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    • 1985
  • Leakage of electrolytes from leaf discs of treated bean (Phaseolus velgaris L.) plant was the criterion used to investigate the effect of four herbicides on the permeability of leaf-cell membrane. CGA 82725 (2-propynyl 2-((3, 5-dichloro-2 pyridinyl) oxy) phenoxy prpanate) at $10^{-3}M$ increased significantly cell membrane permeability within 1 h after 12 h treatment. Significant increase in cell membrane permeability was also detected at $10^{-2}M$ of DOWCO 453 (Haloxy-methyl 2-(4 (3-chloro- 5-(trifuluoromethyl)-2-pyridinyl) phenoxy) propanate. The effect of dinoseb (2-(1-methylpropyl)-4, 6-dintrophenol) on cell premeability was detected at $10^{-4}M$ after 12h. The highest conductivity measurement was obtained from paraquat (1, 1'- dimethyl-4, 4'-bipyridinium ion). Increase in cell membrane permeability was not always associated with injury symptoms such as appearance of necrotic area in leaves.

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