WorldWideScience

Sample records for membrane anion concentration

  1. Anion exchange membrane

    Science.gov (United States)

    Verkade, John G; Wadhwa, Kuldeep; Kong, Xueqian; Schmidt-Rohr, Klaus

    2013-05-07

    An anion exchange membrane and fuel cell incorporating the anion exchange membrane are detailed in which proazaphosphatrane and azaphosphatrane cations are covalently bonded to a sulfonated fluoropolymer support along with anionic counterions. A positive charge is dispersed in the aforementioned cations which are buried in the support to reduce the cation-anion interactions and increase the mobility of hydroxide ions, for example, across the membrane. The anion exchange membrane has the ability to operate at high temperatures and in highly alkaline environments with high conductivity and low resistance.

  2. Simplified production and concentration of HIV-1-based lentiviral vectors using HYPERFlask vessels and anion exchange membrane chromatography

    Science.gov (United States)

    Kutner, Robert H; Puthli, Sharon; Marino, Michael P; Reiser, Jakob

    2009-01-01

    Background During the past twelve years, lentiviral (LV) vectors have emerged as valuable tools for transgene delivery because of their ability to transduce nondividing cells and their capacity to sustain long-term transgene expression in target cells in vitro and in vivo. However, despite significant progress, the production and concentration of high-titer, high-quality LV vector stocks is still cumbersome and costly. Methods Here we present a simplified protocol for LV vector production on a laboratory scale using HYPERFlask vessels. HYPERFlask vessels are high-yield, high-performance flasks that utilize a multilayered gas permeable growth surface for efficient gas exchange, allowing convenient production of high-titer LV vectors. For subsequent concentration of LV vector stocks produced in this way, we describe a facile protocol involving Mustang Q anion exchange membrane chromatography. Results Our results show that unconcentrated LV vector stocks with titers in excess of 108 transduction units (TU) per ml were obtained using HYPERFlasks and that these titers were higher than those produced in parallel using regular 150-cm2 tissue culture dishes. We also show that up to 500 ml of an unconcentrated LV vector stock prepared using a HYPERFlask vessel could be concentrated using a single Mustang Q Acrodisc with a membrane volume of 0.18 ml. Up to 5.3 × 1010 TU were recovered from a single HYPERFlask vessel. Conclusion The protocol described here is easy to implement and should facilitate high-titer LV vector production for preclinical studies in animal models without the need for multiple tissue culture dishes and ultracentrifugation-based concentration protocols. PMID:19220915

  3. Modelling the transport of carbonic acid anions through anion-exchange membranes

    International Nuclear Information System (INIS)

    Nikonenko, V.; Lebedev, K.; Manzanares, J.A.; Pourcelly, G.

    2003-01-01

    Electrodiffusion of carbonate and bicarbonate anions through anion-exchange membranes (AEM) is described on the basis of the Nernst-Planck equations taking into account coupled hydrolysis reactions in the external diffusion boundary layers (DBLs) and internal pore solution. The model supposes local electroneutrality as well as chemical and thermodynamic equilibrium. The transport is considered in three layers being an anion exchange membrane and two adjoining diffusion layers. A mechanism of competitive transport of HCO 3 - and CO 3 2- anions through the membrane which takes into account Donnan exclusion of H + ions is proposed. It is predicted that the pH of the depleting solution decreases and that of the concentrating solution increases during electrodialysis (ED). Eventual deviations from local electroneutrality and local chemical equilibrium are discussed

  4. Water permeation through anion exchange membranes

    Science.gov (United States)

    Luo, Xiaoyan; Wright, Andrew; Weissbach, Thomas; Holdcroft, Steven

    2018-01-01

    An understanding of water permeation through solid polymer electrolyte (SPE) membranes is crucial to offset the unbalanced water activity within SPE fuel cells. We examine water permeation through an emerging class of anion exchange membranes, hexamethyl-p-terphenyl poly (dimethylbenzimidazolium) (HMT-PMBI), and compare it against series of membrane thickness for a commercial anion exchange membrane (AEM), Fumapem® FAA-3, and a series of proton exchange membranes, Nafion®. The HMT-PMBI membrane is found to possess higher water permeabilities than Fumapem® FAA-3 and comparable permeability than Nafion (H+). By measuring water permeation through membranes of different thicknesses, we are able to decouple, for the first time, internal and interfacial water permeation resistances through anion exchange membranes. Permeation resistances on liquid/membrane interface is found to be negligible compared to that for vapor/membrane for both series of AEMs. Correspondingly, the resistance of liquid water permeation is found to be one order of magnitude smaller compared to that of vapor water permeation. HMT-PMBI possesses larger effective internal water permeation coefficient than both Fumapem® FAA-3 and Nafion® membranes (60 and 18% larger, respectively). In contrast, the effective interfacial permeation coefficient of HMT-PMBI is found to be similar to Fumapem® (±5%) but smaller than Nafion®(H+) (by 14%).

  5. Anion-conducting polymer, composition, and membrane

    Science.gov (United States)

    Pivovar, Bryan S [Los Alamos, NM; Thorn, David L [Los Alamos, NM

    2009-09-01

    Anion-conducing polymers and membranes with enhanced stability to aqueous alkali include a polymer backbone with attached sulfonium, phosphazenium, phosphazene, and guanidinium residues. Compositions also with enhanced stability to aqueous alkali include a support embedded with sulfonium, phosphazenium, and guanidinium salts.

  6. Influence of glucose and urea on 125I transport across an anion exchange paper membrane

    International Nuclear Information System (INIS)

    Inoue, Hiroyoshi

    2001-01-01

    In order to study the influence of glucose and urea on the 125 I transport across an anion exchange paper membrane, the transmembrane potential, the fluxes, and the concentrations of 125 I, glucose and urea within the membrane were measured in the Na 125 I concentration-cell system containing glucose or urea. Glucose and urea increased the membrane/solution distribution of the iodide ion, but scarcely affected the diffusion process of iodide ion within the membrane

  7. Anionic lipids and the maintenance of membrane electrostatics in eukaryotes.

    Science.gov (United States)

    Platre, Matthieu Pierre; Jaillais, Yvon

    2017-02-01

    A wide range of signaling processes occurs at the cell surface through the reversible association of proteins from the cytosol to the plasma membrane. Some low abundant lipids are enriched at the membrane of specific compartments and thereby contribute to the identity of cell organelles by acting as biochemical landmarks. Lipids also influence membrane biophysical properties, which emerge as an important feature in specifying cellular territories. Such parameters are crucial for signal transduction and include lipid packing, membrane curvature and electrostatics. In particular, membrane electrostatics specifies the identity of the plasma membrane inner leaflet. Membrane surface charges are carried by anionic phospholipids, however the exact nature of the lipid(s) that powers the plasma membrane electrostatic field varies among eukaryotes and has been hotly debated during the last decade. Herein, we discuss the role of anionic lipids in setting up plasma membrane electrostatics and we compare similarities and differences that were found in different eukaryotic cells.

  8. The effect of membrane diffusion potential change on anionic drugs ...

    African Journals Online (AJOL)

    The effect of membrane potential change on anionic drugs Indomethacin and barbitone induced human erythrocyte shape change and red cell uptake of drug has been studied using microscopy and spectrophotometry techniques respectively. The membrane potential was changed by reducing the extracellular chloride ...

  9. Facile preparation of salt-tolerant anion-exchange membrane adsorber using hydrophobic membrane as substrate.

    Science.gov (United States)

    Fan, Jinxin; Luo, Jianquan; Chen, Xiangrong; Wan, Yinhua

    2017-03-24

    In this study, a polyvinylidene fluoride (PVDF) hydrophobic membrane with high mechanical property was used as substrate to prepare salt-tolerant anion-exchange (STAE) membrane adsorber. Effective hydrophilization and functionalization of PVDF membrane was realized via polydopamine (PDA) deposition, thus overcoming the drawbacks of hydrophobic substrates including poor water permeability, inert property as well as severe non-specific adsorption. The following polyallylamine (PAH) coupling was carried out at pH 10.0, where unprotonated amine groups on PAH chains were more prone to couple with PDA. This membrane adsorber could remain 75% of protein binding capacity when NaCl concentration increased from 0 to 150mM, while its protein binding capacity was independent of flow rate from 10 to 100 membrane volume (MV)/min due to its high mechanical strength (tensile strength: 43.58±2.30MPa). With 200mM NaCl addition at pH 7.5, high purity (above 99%) and high recovery (almost 100%) of Immunoglobulin G (IgG) were obtained when using the STAE membrane adsorber to separate IgG/human serum albumin (HSA) mixture, being similar to that without NaCl at pH 6.0 (both under the flow rate of 10-100MV/min). Finally, the reliable reusability was confirmed by five reuse cycles of protein binding and elution operations. In comparison with commercial membrane adsorber, the new membrane adsorber exhibited a better mechanical property, higher IgG polishing efficiency and reusability, while the protein binding capacity was lower due to less NH 2 density on the membrane. The outcome of this work not only offers a facile and effective approach to prepare membrane adsorbers based on hydrophobic membranes, but also demonstrates great potential of this new designed STAE membrane adsorbers for efficient monoclonal antibody (mAb) polishing. Copyright © 2017 Elsevier B.V. All rights reserved.

  10. Ionic Resistance and Permselectivity Tradeoffs in Anion Exchange Membranes

    KAUST Repository

    Geise, Geoffrey M.

    2013-10-23

    Salinity gradient energy technologies, such as reverse electrodialysis (RED) and capacitive mixing based on Donnan potential (Capmix CDP), could help address the global need for noncarbon-based energy. Anion exchange membranes (AEMs) are a key component in these systems, and improved AEMs are needed in order to optimize and extend salinity gradient energy technologies. We measured ionic resistance and permselectivity properties of quaternary ammonium-functionalized AEMs based on poly(sulfone) and poly(phenylene oxide) polymer backbones and developed structure-property relationships between the transport properties and the water content and fixed charge concentration of the membranes. Ion transport and ion exclusion properties depend on the volume fraction of water in the polymer membrane, and the chemical nature of the polymer itself can influence fine-tuning of the transport properties to obtain membranes with other useful properties, such as chemical and dimensional stability. The ionic resistance of the AEMs considered in this study decreased by more than 3 orders of magnitude (i.e., from 3900 to 1.6 Ω m) and the permselectivity decreased by 6% (i.e., from 0.91 to 0.85) as the volume fraction of water in the polymer was varied by a factor of 3.8 (i.e., from 0.1 to 0.38). Water content was used to rationalize a tradeoff relationship between the permselectivity and ionic resistance of these AEMs whereby polymers with higher water content tend to have lower ionic resistance and lower permselectivity. The correlation of ion transport properties with water volume fraction and fixed charge concentration is discussed with emphasis on the importance of considering water volume fraction when interpreting ion transport data. © 2013 American Chemical Society.

  11. Reducing nitrogen crossover in microbial reverse-electrodialysis cells by using adjacent anion exchange membranes and anion exchange resin

    KAUST Repository

    Wallack, Maxwell J.; Geise, Geoffrey M.; Hatzell, Marta C.; Hickner, Michael A.; Logan, Bruce E.

    2015-01-01

    Microbial reverse electrodialysis cells (MRECs) combine power generation from salinity gradient energy using reverse electrodialysis (RED), with power generation from organic matter using a microbial fuel cell. Waste heat can be used to distill ammonium bicarbonate into high (HC) and low salt concentration (LC) solutions for use in the RED stack, but nitrogen crossover into the anode chamber must be minimized to avoid ammonia loses, and foster a healthy microbial community. To reduce nitrogen crossover, an additional low concentration (LC) chamber was inserted before the anode using an additional anion exchange membrane (AEM) next to another AEM, and filled with different amounts of anion or cation ion exchange resins. Addition of the extra AEM increased the ohmic resistance of the test RED stack from 103 Ω cm2 (1 AEM) to 295 Ω cm2 (2 AEMs). However, the use of the anion exchange resin decreased the solution resistance of the LC chamber by 74% (637 Ω cm2, no resin; 166 Ω cm2 with resin). Nitrogen crossover into the anode chamber was reduced by up to 97% using 50% of the chamber filled with an anion exchange resin compared to the control (no additional chamber). The added resistance contributed by the use of the additional LC chamber could be compensated for by using additional LC and HC membrane pairs in the RED stack.

  12. Membrane distillation for milk concentration

    NARCIS (Netherlands)

    Moejes, S.N.; Romero Guzman, Maria; Hanemaaijer, J.H.; Barrera, K.H.; Feenstra, L.; Boxtel, van A.J.B.

    2015-01-01

    Membrane distillation is an emerging technology to concentrate liquid products while producing high quality water as permeate. Application for desalination has been studied extensively the past years, but membrane distillation has also potential to produce concentrated food products like

  13. Mimicking the cell membrane: bio-inspired simultaneous functions with monovalent anion selectivity and antifouling properties of anion exchange membrane

    Science.gov (United States)

    Zhao, Yan; Liu, Huimin; Tang, Kaini; Jin, Yali; Pan, Jiefeng; der Bruggen, Bart Van; Shen, Jiangnan; Gao, Congjie

    2016-11-01

    A new bio-inspired method was applied in this study to simultaneously improve the monovalent anion selectivity and antifouling properties of anion exchange membranes (AEMs). Three-layer architecture was developed by deposition of polydopamine (PDA) and electro-deposition of N-O-sulfonic acid benzyl chitosan (NSBC). The innermost and outermost layers were PDA with different deposition time. The middle layer was prepared by NSBC. Fourier transform infrared spectroscopy and scanning electron microscopy confirmed that PDA and NSBC were successfully modified on the surfaces of AEMs. The contact angle of the membranes indicated an improved hydrophilicity of the modified membranes. A series of electrodialysis experiments in which Cl-/SO42- separation was studied, demonstrating the monovalent anion selectivity of the samples. The Cl-/SO42- permselectivity of the modified membranes can reach up to 2.20, higher than that of the commercial membrane (only 0.78) during 90 minutes in electrodialysis (ED). The increase value of the resistance of the membranes was also measured to evaluate the antifouling properties. Sodium dodecyl benzene sulfonate (SDBS) was used as the fouling material in the ED process and the membrane area resistance of modified membrane increase value of was only 0.08 Ωcm2 30 minutes later.

  14. Mimicking the cell membrane: bio-inspired simultaneous functions with monovalent anion selectivity and antifouling properties of anion exchange membrane

    Science.gov (United States)

    Zhao, Yan; Liu, Huimin; Tang, Kaini; Jin, Yali; Pan, Jiefeng; der Bruggen, Bart Van; Shen, Jiangnan; Gao, Congjie

    2016-01-01

    A new bio-inspired method was applied in this study to simultaneously improve the monovalent anion selectivity and antifouling properties of anion exchange membranes (AEMs). Three-layer architecture was developed by deposition of polydopamine (PDA) and electro-deposition of N-O-sulfonic acid benzyl chitosan (NSBC). The innermost and outermost layers were PDA with different deposition time. The middle layer was prepared by NSBC. Fourier transform infrared spectroscopy and scanning electron microscopy confirmed that PDA and NSBC were successfully modified on the surfaces of AEMs. The contact angle of the membranes indicated an improved hydrophilicity of the modified membranes. A series of electrodialysis experiments in which Cl−/SO42− separation was studied, demonstrating the monovalent anion selectivity of the samples. The Cl−/SO42− permselectivity of the modified membranes can reach up to 2.20, higher than that of the commercial membrane (only 0.78) during 90 minutes in electrodialysis (ED). The increase value of the resistance of the membranes was also measured to evaluate the antifouling properties. Sodium dodecyl benzene sulfonate (SDBS) was used as the fouling material in the ED process and the membrane area resistance of modified membrane increase value of was only 0.08 Ωcm2 30 minutes later. PMID:27853255

  15. based anion exchange membrane for alkaline polymer electrolyte

    Indian Academy of Sciences (India)

    Administrator

    Abstract. Hydroxyl ion (OH–) conducting anion exchange membranes based on modified poly (phenylene oxide) are fabricated for their application in alkaline polymer electrolyte fuel cells (APEFCs). In the present study, chloromethylation of poly(phenylene oxide) (PPO) is performed by aryl substitution rather than benzyl.

  16. Anion-exchange membranes in electrochemical energy systems

    NARCIS (Netherlands)

    Varcoe, J.R.; Atanassov, P.; Dekel, D.R.; Herring, A.M.; Hickner, M.A.; Kohl, P.A.; Kucernak, A. R.; Mustain, W.E.; Nijmeijer, K.; Scott, Keith; Xu, Tongwen; Zhuang, Lin

    2014-01-01

    This article provides an up-to-date perspective on the use of anion-exchange membranes in fuel cells, electrolysers, redox flow batteries, reverse electrodialysis cells, and bioelectrochemical systems (e.g. microbial fuel cells). The aim is to highlight key concepts, misconceptions, the current

  17. Polyvinyl alcohol (PVA) and sulfonated polyetheretherketone (SPEEK) anion exchange membrane for fuel cell

    CSIR Research Space (South Africa)

    Luo, H

    2010-08-31

    Full Text Available less than proton exchange membrane systems using alcohol as fuel. Many anion exchange membranes based on quaternised polymers have been developed and studied for AMFC3-5. The quaternary ammonium functional groups are the anion conductors...

  18. Selective preconcentration of iodide in presence of iodate using a plasticized anion-exchange membrane

    International Nuclear Information System (INIS)

    Bhagat, Preeti; Rajurkar, N.S.; Acharya, R.; Pandey, A.K.; Nair, A.G.C.; Reddy, A.V.R.

    2006-01-01

    In the present work, the hydrophobic anion-exchange membranes were prepared by physical immobilization of Aliquat-336 (AL) in the cellulose triacetate (CTA) matrix plasticized with dioctyl phthalate (DOP). The uptake of I - in this membrane was examined in aqueous sample in the presence of IO 3 - ions in varying concentrations. In order to provide better discrimination between I - and IO 3 - ions, the uptake studies were carried out using three different counterions (CL - , Br - and NO 3 - ) in the membrane. The results of these studies are described in this paper

  19. Ion-exchange concentration of inorganic anions from aqueous solution

    Directory of Open Access Journals (Sweden)

    L. P. Bondareva

    2016-01-01

    Full Text Available Monitoring of natural waters in the present time - consuming process, the accuracy of which is influenced by many factors: the composition of water, the presence of impurities and "interfering" components. The water sample preparation process includes the step of concentration and separation of ions determined. The most versatile, efficient, and frequently used method is the concentration of inorganic anions from aqueous solutions by ion exchanger, which can optimize the composition of water to the optimal for identification and quantitative determination of anions. The characteristics of sorption chloride, nitrate and sulfate ions of basic anion exchange resin AВ-17 and Purolite A430 were compared in the article. The constants of protolysis of ion exchangers both AB 17 and Purolite A430 are the same and equal 0.037 ± 0,002. The value of total capacity (POE Purolite A430 was 4.3 mmol/g, AB 17 – 3.4 mmol/g. The studied ion exchangers have the same type of ionic groups – quaternary ammonium, but their number and denotes differ. The number of quaternary ammonium groups is higher in Purolite A430, respectively the number of absorbed anions of these ion exchanger is higher. The values of dynamic exchange capacity (DOE of ion exchanger Purolite A430 is higher than these values of AB-17 and equal to 1.48 ± 0.03 mmol / dm3 for chloride ion, 1.50 ± 0.03 mmol / dm3 for nitrate ion, 1.62 ± 0.03 mmol / dm3 for sulfate ion. The values of the POE and DOE of anion-exchange resins Purolite A430 and AV-17 and the characteristics of the individual sorption of chloride, nitrate, sulfate ions showed an advantage of the Purolite for the concentrationing of anions. It is found that times of anions sorption from triple-anion solutions by Purolite A430 are significantly different for different anions, and these times are close for anion-exchanger AV-17. It proves the possibility of quantitative separation and concentration by anion-exchanger Purolite A430.

  20. Anion analysis in uranium more concentrates by ion chromatography

    International Nuclear Information System (INIS)

    Badaut, V.

    2009-01-01

    In the present exploratory study, the applicability of anionic impurities or attributing nuclear material to a certain chemical process or origin has been investigated. Anions (e.g., nitrate, sulphate, fluoride, chloride) originate from acids or salt solutions that are used for processing of solutions containing uranium or plutonium. The study focuses on uranium ore concentrates ('yellow cakes') originating from different mines. Uranium is mined from different types of ore body and depending on the type of rock, different chemical processes for leaching, dissolving and precipitating the uranium need to be applied. Consequently, the anionic patterns observed in he products of these processes (the 'ore concentrates') are different. The concentrations of different anionic species were measured by ion chromatography using conductivity detection. The results show clear differences of anion concentrations and patterns between samples from different uranium mines. Besides this, differences between sampling campaigns n a same mine were also observed indicating that the uranium ore is not homogeneous in a mine. These within-mine variations, however, were smaller than the between-mine variations. (author)

  1. Anion exchange membrane based on alkali doped poly(2,5-benzimidazole) for alkaline membrane fuel cell

    CSIR Research Space (South Africa)

    Luo, H

    2010-03-01

    Full Text Available was prepared. The alkali doped poly(2,5-benzimidazole) membrane is a promising candidate as anion exchange membrane for fuel cell application. The alkali doped poly(2,5-benzimidazole) membrane reached an anion conductivity of 2.3×10-2 S cm-1 at room temperature...

  2. Procedure for reducing hydrogen ion concentration in acidic anion eluate

    International Nuclear Information System (INIS)

    Parobek, P.; Baloun, S.; Plevac, S.

    1992-01-01

    A procedure is suggested for reducing the concentration of hydrogen ions in the acidic anionic eluate formed during the separation of uranium. The procedure involves anex elution, precipitation, filtration, precipitate rinsing, and anex rinsing. The procedure is included in the uranium elution process and requires at least one ion exchanger column and at least one tank in the continuous or discontinuous mode. Sparing the neutralizing agent by reducing the hydrogen ion concentration in the acidic anionic eluate is a major asset of this procedure. (Z.S.). 1 fig

  3. Ionic Resistance and Permselectivity Tradeoffs in Anion Exchange Membranes

    KAUST Repository

    Geise, Geoffrey M.; Hickner, Michael A.; Logan, Bruce E.

    2013-01-01

    (sulfone) and poly(phenylene oxide) polymer backbones and developed structure-property relationships between the transport properties and the water content and fixed charge concentration of the membranes. Ion transport and ion exclusion properties depend

  4. Review of cell performance in anion exchange membrane fuel cells

    Science.gov (United States)

    Dekel, Dario R.

    2018-01-01

    Anion exchange membrane fuel cells (AEMFCs) have recently received increasing attention since in principle they allow for the use of non-precious metal catalysts, which dramatically reduces the cost per kilowatt of power in fuel cell devices. Until not long ago, the main barrier in the development of AEMFCs was the availability of highly conductive anion exchange membranes (AEMs); however, improvements on this front in the past decade show that newly developed AEMs have already reached high levels of conductivity, leading to satisfactory cell performance. In recent years, a growing number of research studies have reported AEMFC performance results. In the last three years, new records in performance were achieved. Most of the literature reporting cell performance is based on hydrogen-AEMFCs, although an increasing number of studies have also reported the use of fuels others than hydrogen - such as alcohols, non-alcohol C-based fuels, as well as N-based fuels. This article reviews the cell performance and performance stability achieved in AEMFCs through the years since the first reports in the early 2000s.

  5. Removal of 125I from radioactive experimental waste with an anion exchange paper membrane

    International Nuclear Information System (INIS)

    Inoue, Hiroyoshi; Kagoshima, Mayumi

    2000-01-01

    The behavior of radioactive iodide and chloride ions through an anion exchange paper membrane to remove 125 I from radioactive experimental waste has been studied with nonequilibrium thermodynamic analyses. Anion exchange paper membrane was found to be electroconductively more permeable to iodide ion than to chloride ion. The iodide ion bound more strongly to the anion exchange site within a membrane phase than the chloride ion by more than twice. The results suggested that an anion exchange paper membrane was appropriate for the filtration removal system

  6. Ca2+ and Mg2+-enhanced reduction of arsenazo III to its anion free radical metabolite and generation of superoxide anion by an outer mitochondrial membrane azoreductase.

    Science.gov (United States)

    Moreno, S N; Mason, R P; Docampo, R

    1984-12-10

    At the concentrations usually employed as a Ca2+ indicator, arsenazo III underwent a one-electron reduction by rat liver mitochondria to produce an azo anion radical as demonstrated by electron-spin resonance spectroscopy. Either NADH or NADPH could serve as a source of reducing equivalents for the production of this free radical by intact rat liver mitochondria. Under aerobic conditions, addition of arsenazo III to rat liver mitochondria produced an increase in electron flow from NAD(P)H to molecular oxygen, generating superoxide anion. NAD(P)H generated from endogenous mitochondrial NAD(P)+ by intramitochondrial reactions could not be used for the NAD(P)H azoreductase reaction unless the mitochondria were solubilized by detergent or anaerobiosis. In addition, NAD(P)H azoreductase activity was higher in the crude outer mitochondrial membrane fraction than in mitoplasts and intact mitochondria. The steady-state concentration of the azo anion radical and the arsenazo III-stimulated cyanide-insensitive oxygen consumption were enhanced by calcium and magnesium, suggesting that, in addition to an enhanced azo anion radical-stabilization by complexation with the metal ions, enhanced reduction of arsenazo III also occurred. Accordingly, addition of cations to crude outer mitochondrial membrane preparations increased arsenazo III-stimulated cyanide-insensitive O2 consumption, H2O2 formation, and NAD(P)H oxidation. Antipyrylazo III was much less effective than arsenazo III in increasing superoxide anion formation by rat liver mitochondria and gave a much weaker electron spin resonance spectrum of an azo anion radical. These results provide direct evidence of an azoreductase activity associated with the outer mitochondrial membrane and of a stimulation of arsenazo III reduction by cations.

  7. Importance of balancing membrane and electrode water in anion exchange membrane fuel cells

    Science.gov (United States)

    Omasta, T. J.; Wang, L.; Peng, X.; Lewis, C. A.; Varcoe, J. R.; Mustain, W. E.

    2018-01-01

    Anion exchange membrane fuel cells (AEMFCs) offer several potential advantages over proton exchange membrane fuel cells (PEMFCs), most notably to overcome the cost barrier that has slowed the growth and large scale implementation of fuel cells for transportation. However, limitations in performance have held back AEMFCs, specifically in the areas of stability, carbonation, and maximum achievable current and power densities. In order for AEMFCs to contend with PEMFCs for market viability, it is necessary to realize a competitive cell performance. This work demonstrates a new benchmark for a H2/O2 AEMFC with a peak power density of 1.4 W cm-2 at 60 °C. This was accomplished by taking a more precise look at balancing necessary membrane hydration while preventing electrode flooding, which somewhat surprisingly can occur both at the anode and the cathode. Specifically, radiation-grafted ETFE-based anion exchange membranes and anion exchange ionomer powder, functionalized with benchmark benzyltrimethylammonium groups, were utilized to examine the effects of the following parameters on AEMFC performance: feed gas flow rate, the use of hydrophobic vs. hydrophilic gas diffusion layers, and gas feed dew points.

  8. Development of Preparation Methods for Alkaline Anion Exchange Membranes by Radiation

    International Nuclear Information System (INIS)

    Shin, Jun Hwa; Nho, Young Chang; Sohn, Joon Yong

    2010-01-01

    The objective of this project is to contribute to the environmentally friendly fuel cell system by developing a radiation grafting method for the preparation of anion exchange membranes for alkaline fuel cell and finally to the radiation technology industry. In this project, the preparation methods for the VBC-grafted fluoropolymer films using radiation have been developed and anion exchange membranes have been prepared via the reaction between the VBC-grafted fluoropolymer films and amines. The prepared anion exchange membranes were characterized and the performance of the membranes were evaluated

  9. Preparation of anion exchange membrane using polyvinyl chloride (PVC) for alkaline water electrolysis

    Energy Technology Data Exchange (ETDEWEB)

    Hwang, Gab-Jin; Bong, Soo-Yeon; Ryu, Cheol-Hwi [Hoseo University, Asan (Korea, Republic of); Lim, Soo-Gon [Energy and Machinery Korea Co., Ltd., Changwon (Korea, Republic of); Choi, Ho-Sang [Kyungil University, Gyeongsan (Korea, Republic of)

    2015-09-15

    An anion exchange membrane was prepared by the chloromethylation and the amination of polyvinyl chloride (PVC), as the base polymer. The membrane properties of the prepared anion exchange membrane, including ionic conductivity, ion exchange capacity, and water content were measured. The ionic conductivity of the prepared anion exchange membrane was in the range of 0.098x10{sup -2} -7.0x10{sup -2}S cm{sup -1}. The ranges of ion exchange capacity and water content were 1.9-3.7meq./g-dry-membrane and 35.1-63.1%, respectively. The chemical stability of the prepared anion exchange membrane was tested by soaking in 30 wt% KOH solution to determine its availability as a separator in the alkaline water electrolysis. The ionic conductivity during the chemical stability test largely did not change.

  10. Determination of arsenate in water by anion selective membrane electrode using polyurethane–silica gel fibrous anion exchanger composite

    Energy Technology Data Exchange (ETDEWEB)

    Khan, Asif Ali, E-mail: asifkhan42003@yahoo.com; Shaheen, Shakeeba, E-mail: shakeebashaheen@ymail.com

    2014-01-15

    Highlights: • PU–Si gel is new anion exchanger material synthesized and characterized. • This material used as anion exchange membrane is applied for electroanalytical studies. • The method for detection and determination of AsO{sub 4}{sup 3−} in traces amounts discussed. • The results are also verified from arsenic analyzer. -- Abstract: Polyurethane (PU)–silica (Si gel) based fibrous anion exchanger composites were prepared by solid–gel polymerization of polyurethane in the presence of different amounts of silica gel. The formation of PU–Si gel fibrous anion exchanger composite was characterized by Fourier transform infra-red spectroscopy (FTIR), X-ray diffraction (XRD), thermogravimetric analysis (TGA-DTA), scanning electron microscopy (SEM) and elemental analysis. The membrane having a composition of 5:3 (PU:Si gel) shows best results for water content, porosity, thickness and swelling. Our studies show that the present ion selective membrane electrode is selective for arsenic, having detection limit (1 × 10{sup −8} M to 1 × 10{sup −1} M), response time (45 s) and working pH range (5–8). The selectivity coefficient values for interfering ions indicate good selectivity for arsenate (AsO{sub 4}{sup 3−}) over interfering anions. The accuracy of the detection limit results was compared by PCA-Arsenomat.

  11. Hybrid capacitive deionization with anion-exchange membranes for lithium extraction

    OpenAIRE

    Siekierka Anna; Bryjak Marek

    2017-01-01

    Lithium is considered to be a critical material for various industrial fields. We present our studies on extraction lithium from diluted aqueous solution by novel hybrid system based on a membrane capacitive deionization and batteries desalination. Hybrid CDI is comprised by a lithium selective adsorbent, activated carbon electrode and anion-exchange membranes. Here, we demonstrated implication of various type of anion-exchange membranes and influence their properties on effective capacity an...

  12. Characterization of an anionic-exchange membranes for direct methanol alkaline fuel cells

    Energy Technology Data Exchange (ETDEWEB)

    Abuin, Graciela C. [Centro de Procesos Superficiales, Instituto Nacional de Tecnologia Industrial (INTI), Av. Gral. Paz 5445, B1650KNA, San Martin, Buenos Aires (Argentina); Nonjola, Patrick; Mathe, Mkhulu K. [Council for Scientific and Industrial Research (CSIR), Material Science and Manufacturing, PO Box 395, Brumeria, Pretoria 0001 (South Africa); Franceschini, Esteban A.; Izraelevitch, Federico H.; Corti, Horacio R. [Departamento de Fisica de la Materia Condensada, Comision Nacional de Energia Atomica (CNEA), Av. Gral. Paz 1499, B1650KNA, San Martin, Buenos Aires (Argentina)

    2010-06-15

    Ammonium quaternized polymers such as poly (arylene ether sulfones) are being developed and studied as candidates of ionomeric materials for application in alkaline fuel cells, due to their low cost and promising electrochemical properties. In this work, a quaternary ammonium polymer was synthesized by chloromethylation of a commercial polysulfone followed by amination process. Quaternized polysulfone membrane properties such us water and water-methanol uptake, electrical conductivity and Young's modulus were evaluated and compared to Nafion 117, commonly employed in direct methanol fuel cells. The anionic polysulfone membrane sorbs more water than Nafion all over the whole range of water activities, but it uptakes much less methanol as compared to Nafion. The specific conductivity of the fully hydrated polysulfone membrane equilibrated with KOH solutions at ambient temperature increases with the KOH concentration, reaching a maximum of 0.083 S cm{sup -1} for 2 M KOH, slightly less conductive than Nafion 117. The elastic modulus of the polysulfone membranes inmersed in water is similar to that reported for Nafion membranes under the same conditions. We concluded that quaternized polysulfone membrane are good candidates as electrolytes in alkaline direct methanol fuel cells. (author)

  13. Highly conductive side chain block copolymer anion exchange membranes.

    Science.gov (United States)

    Wang, Lizhu; Hickner, Michael A

    2016-06-28

    Block copolymers based on poly(styrene) having pendent trimethyl styrenylbutyl ammonium (with four carbon ring-ionic group alkyl linkers) or benzyltrimethyl ammonium groups with a methylene bridge between the ring and ionic group were synthesized by reversible addition-fragmentation radical (RAFT) polymerization as anion exchange membranes (AEMs). The C4 side chain polymer showed a 17% increase in Cl(-) conductivity of 33.7 mS cm(-1) compared to the benzyltrimethyl ammonium sample (28.9 mS cm(-1)) under the same conditions (IEC = 3.20 meq. g(-1), hydration number, λ = ∼7.0, cast from DMF/1-propanol (v/v = 3 : 1), relative humidity = 95%). As confirmed by small angle X-ray scattering (SAXS), the side chain block copolymers with tethered ammonium cations showed well-defined lamellar morphologies and a significant reduction in interdomain spacing compared to benzyltrimethyl ammonium containing block copolymers. The chemical stabilities of the block copolymers were evaluated under severe, accelerated conditions, and degradation was observed by (1)H NMR. The block copolymer with C4 side chain trimethyl styrenylbutyl ammonium motifs displayed slightly improved stability compared to that of a benzyltrimethyl ammonium-based AEM at 80 °C in 1 M NaOD aqueous solution for 30 days.

  14. Fundamental characteristics study of anion-exchange PVDF-SiO(2) membranes.

    Science.gov (United States)

    Zuo, Xingtao; Shi, Wenxin; Yu, Shuili; He, Jiajie

    2012-01-01

    A new type of poly(vinylidene fluoride)(PVDF)-SiO(2) hybrid anion-exchange membrane was prepared by blending method. The anion-exchange groups were introduced by the reaction of epoxy groups with trimethylamine (TMA). Contact angle between water and the membrane surface was measured to characterize the hydrophilicity change of the membrane surface. The effects of nano-sized SiO(2) particles in the membrane-forming materials on the membrane mechanical properties and conductivity were also investigated. The experimental results indicated that PVDF-SiO(2) anion-exchange membranes exhibited better water content, ion-exchange capacity, conductivity and mechanic properties, and so may find potential applications in alkaline membrane fuel cells and water treatment processes.

  15. Local impermeant anions establish the neuronal chloride concentration

    DEFF Research Database (Denmark)

    Glykys, J; Dzhala, V; Egawa, K

    2014-01-01

    Neuronal intracellular chloride concentration [Cl(-)](i) is an important determinant of γ-aminobutyric acid type A (GABA(A)) receptor (GABA(A)R)-mediated inhibition and cytoplasmic volume regulation. Equilibrative cation-chloride cotransporters (CCCs) move Cl(-) across the membrane, but accumulat...

  16. Mechanism of action of anions on the electron transport chain in thylakoid membranes of higher plants.

    Science.gov (United States)

    Singh-Rawal, Pooja; Zsiros, Ottó; Bharti, Sudhakar; Garab, Gyozo; Jajoo, Anjana

    2011-04-01

    With an aim to improve our understanding of the mechanisms behind specific anion effects in biological membranes, we have studied the effects of sodium salts of anions of varying valency in thylakoid membranes. Rates of electron transport of PS II and PS I, 77K fluorescence emission and excitation spectra, cyclic electron flow around PS I and circular dichroism (CD) spectra were measured in thylakoid membranes in order to elucidate a general mechanism of action of inorganic anions on photosynthetic electron transport chain. Re-distribution of absorbed excitation energy has been observed as a signature effect of inorganic anions. In the presence of anions, such as nitrite, sulphate and phosphate, distribution of absorbed excitation energy was found to be more in favor of Photosystem I (PS I). The amount of energy distributed towards PS I depended on the valency of the anion. In this paper, we propose for the first time that energy re-distribution and its valence dependence may not be the effect of anions per se. The entry of negative charge (anion) is accompanied by influx of positive charge (protons) to maintain a balance of charge across the thylakoid membranes. As reflected by the CD spectra, the observed energy re-distribution could be a result of structural rearrangements of the protein complexes of PS II caused by changes in the ionic environment of the thylakoid lumen.

  17. A novel anion exchange membrane from polystyrene (ethylene butylene) polystyrene: Synthesis and characterization

    International Nuclear Information System (INIS)

    Vinodh, Rajangam; Ilakkiya, Arjunan; Elamathi, Swaminathan; Sangeetha, Dharmalingam

    2010-01-01

    We look forward for an eco-friendly hydrocarbon polymer with higher molecular weight for the preparation of an anion exchange membrane. Polystyrene ethylene butylene polystyrene (PSEBS) was chosen as the polymer matrix. The anion exchange membrane was prepared from PSEBS tri-block co-polymer and then the properties were characterized for alkaline fuel cell application. The preparation of anion exchange polymer involved two steps namely chloromethylation and quaternization. The anion exchange membrane with high conductivity has been prepared by introducing quaternary ammonium groups in to the polymer. Finally, the membrane was prepared using solution casting method. The solution casting method yields highly hydrophilic membranes with uniform structure that were suitable for electrochemical applications. The efficiency of the entrapment was monitored by swelling ratio, chemical stability and ion exchange measurement. The characteristic structural properties of the membrane were investigated by FT-IR spectroscopy and 1 H NMR spectroscopy. The thermal stability of the membrane was characterized by TGA, DSC and DMA (dynamic mechanical analysis). The prepared uniform electrolyte membrane in this study has high thermal and chemical stability. The surface morphology and elemental composition of the quaternized PSEBS was determined by SEM-EDXA techniques, respectively. The measured hydroxyl ion conductivity of the synthesized alkaline PSEBS polymer electrolyte membrane showed ionic conductivity in the range of 10 -3 S/cm in deionized water at room temperature. It was found that the substitution provided a flexible, chemically and thermally stable membrane. Hence, the membrane will have potential application in the alkaline fuel cell.

  18. The recovery of zinc from hot galvanizing slag in an anion-exchange membrane electrolysis reactor

    Energy Technology Data Exchange (ETDEWEB)

    Ren Xiulian [College of Ocean, Harbin Institute of Technology at Weihai, Weihai 264209 (China); Wei Qifeng, E-mail: weiqifeng163@163.com [College of Ocean, Harbin Institute of Technology at Weihai, Weihai 264209 (China); Hu Surong; Wei Sijie [College of Ocean, Harbin Institute of Technology at Weihai, Weihai 264209 (China)

    2010-09-15

    This paper reports the optimization of the process parameters for recovery of zinc from hot galvanizing slag in an anion-exchange membrane electrolysis reactor. The experiments were carried out in an ammoniacal ammonium chloride system. The influence of composition of electrolytes, pH, stirring rate, current density and temperature, on cathodic current efficiency, specific power consumption and anodic dissolution of Zn were investigated. The results indicate that the cathode current efficiency increases and the hydrogen evolution decreased with increasing the cathode current density. The partial current for electrodeposition of Zn has liner relationship with {omega}{sup 1/2} ({omega}: rotation rate). The highest current efficiency for dissolving zinc was obtained when NH{sub 4}Cl concentration was 53.46 g L{sup -1} and the anodic dissolution of zinc was determined by mass transfer rate at stirring rate 0-300 r min{sup -1}. Increase in temperature benefits to improve CE and dissolution of Zn, and reduce cell voltage. Initial pH of electrolytes plays an important role in the deposition and anodic dissolution of Zn. The results of single factor experiment show that about 50% energy consumption was saved for electrodeposition of Zn in the anion-exchange membrane electrolysis reactor.

  19. The recovery of zinc from hot galvanizing slag in an anion-exchange membrane electrolysis reactor.

    Science.gov (United States)

    Ren, Xiulian; Wei, Qifeng; Hu, Surong; Wei, Sijie

    2010-09-15

    This paper reports the optimization of the process parameters for recovery of zinc from hot galvanizing slag in an anion-exchange membrane electrolysis reactor. The experiments were carried out in an ammoniacal ammonium chloride system. The influence of composition of electrolytes, pH, stirring rate, current density and temperature, on cathodic current efficiency, specific power consumption and anodic dissolution of Zn were investigated. The results indicate that the cathode current efficiency increases and the hydrogen evolution decreased with increasing the cathode current density. The partial current for electrodeposition of Zn has liner relationship with omega(1/2) (omega: rotation rate). The highest current efficiency for dissolving zinc was obtained when NH(4)Cl concentration was 53.46 g L(-1) and the anodic dissolution of zinc was determined by mass transfer rate at stirring rate 0-300 r min(-1). Increase in temperature benefits to improve CE and dissolution of Zn, and reduce cell voltage. Initial pH of electrolytes plays an important role in the deposition and anodic dissolution of Zn. The results of single factor experiment show that about 50% energy consumption was saved for electrodeposition of Zn in the anion-exchange membrane electrolysis reactor. Copyright 2010 Elsevier B.V. All rights reserved.

  20. The recovery of zinc from hot galvanizing slag in an anion-exchange membrane electrolysis reactor

    International Nuclear Information System (INIS)

    Ren Xiulian; Wei Qifeng; Hu Surong; Wei Sijie

    2010-01-01

    This paper reports the optimization of the process parameters for recovery of zinc from hot galvanizing slag in an anion-exchange membrane electrolysis reactor. The experiments were carried out in an ammoniacal ammonium chloride system. The influence of composition of electrolytes, pH, stirring rate, current density and temperature, on cathodic current efficiency, specific power consumption and anodic dissolution of Zn were investigated. The results indicate that the cathode current efficiency increases and the hydrogen evolution decreased with increasing the cathode current density. The partial current for electrodeposition of Zn has liner relationship with ω 1/2 (ω: rotation rate). The highest current efficiency for dissolving zinc was obtained when NH 4 Cl concentration was 53.46 g L -1 and the anodic dissolution of zinc was determined by mass transfer rate at stirring rate 0-300 r min -1 . Increase in temperature benefits to improve CE and dissolution of Zn, and reduce cell voltage. Initial pH of electrolytes plays an important role in the deposition and anodic dissolution of Zn. The results of single factor experiment show that about 50% energy consumption was saved for electrodeposition of Zn in the anion-exchange membrane electrolysis reactor.

  1. Production and application of cation/anion exchange membranes of high performance

    International Nuclear Information System (INIS)

    Xu Zhili; Tan Chunhong; Yang Xiangmin

    1995-01-01

    A third affiliated factory of our university has been established for the production in batches of cation/anion exchange membranes of high performance, trade marks of which are HF-1 and HF-2. Membrane products have been applied in various fields (including industries and research institutions) with great success

  2. Hybrid capacitive deionization with anion-exchange membranes for lithium extraction

    Directory of Open Access Journals (Sweden)

    Siekierka Anna

    2017-01-01

    Full Text Available Lithium is considered to be a critical material for various industrial fields. We present our studies on extraction lithium from diluted aqueous solution by novel hybrid system based on a membrane capacitive deionization and batteries desalination. Hybrid CDI is comprised by a lithium selective adsorbent, activated carbon electrode and anion-exchange membranes. Here, we demonstrated implication of various type of anion-exchange membranes and influence their properties on effective capacity and energy requirements in charge/discharge steps. We described a configuration with anion-exchange membrane characterized by adsorption capacity of 35 mg/g of Li+ with 0.08Wh/g and removal efficiency of 60 % of lithium ions, using novel selective desalination technique.

  3. Hybrid capacitive deionization with anion-exchange membranes for lithium extraction

    Science.gov (United States)

    Siekierka, Anna; Bryjak, Marek

    2017-11-01

    Lithium is considered to be a critical material for various industrial fields. We present our studies on extraction lithium from diluted aqueous solution by novel hybrid system based on a membrane capacitive deionization and batteries desalination. Hybrid CDI is comprised by a lithium selective adsorbent, activated carbon electrode and anion-exchange membranes. Here, we demonstrated implication of various type of anion-exchange membranes and influence their properties on effective capacity and energy requirements in charge/discharge steps. We described a configuration with anion-exchange membrane characterized by adsorption capacity of 35 mg/g of Li+ with 0.08Wh/g and removal efficiency of 60 % of lithium ions, using novel selective desalination technique.

  4. Calibration procedures for the quantitative determination of membrane potential in human cells using anionic dyes.

    Science.gov (United States)

    Klapperstück, Thomas; Glanz, Dagobert; Hanitsch, Stefan; Klapperstück, Manuela; Markwardt, Fritz; Wohlrab, Johannes

    2013-07-01

    Quantitative determinations of the cell membrane potential of lymphocytes (Wilson et al., J Cell Physiol 1985;125:72-81) and thymocytes (Krasznai et al., J Photochem Photobiol B 1995;28:93-99) using the anionic dye DiBAC4 (3) proved that dye depletion in the extracellular medium as a result of cellular uptake can be negligible over a wide range of cell densities. In contrast, most flow cytometric studies have not verified this condition but rather assumed it from the start. Consequently, the initially prepared extracellular dye concentration has usually been used for the calculation of the Nernst potential of the dye. In this study, however, external dye depletion could be observed in both large IGR-1 and small LCL-HO cells under experimental conditions, which have often been applied routinely in spectrofluorimetry and flow cytometry. The maximum cell density at which dye depletion could be virtually avoided was dependent on cell size and membrane potential and definitely needed to be taken into account to ensure reliable results. In addition, accepted calibration procedures based on the partition of sodium and potassium (Goldman-Hodgkin-Katz equation) or potassium alone (Nernst equation) were performed by flow cytometry on cell suspensions with an appropriately low cell density. The observed extensive lack of concordance between the correspondingly calculated membrane potential and the equilibrium potential of DiBAC4 (3) revealed that these methods require the additional measurement of cation parameters (membrane permeability and/or intracellular concentration). In contrast, due to the linear relation between fluorescence and low DiBAC4 (3) concentrations, the Nernst potential of the dye for totally depolarized cells can be reliably used for calibration with an essentially lower effort and expense. Copyright © 2013 International Society for Advancement of Cytometry.

  5. Multi-layer membrane model for mass transport in a direct ethanol fuel cell using an alkaline anion exchange membrane

    Science.gov (United States)

    Bahrami, Hafez; Faghri, Amir

    2012-11-01

    A one-dimensional, isothermal, single-phase model is presented to investigate the mass transport in a direct ethanol fuel cell incorporating an alkaline anion exchange membrane. The electrochemistry is analytically solved and the closed-form solution is provided for two limiting cases assuming Tafel expressions for both oxygen reduction and ethanol oxidation. A multi-layer membrane model is proposed to properly account for the diffusive and electroosmotic transport of ethanol through the membrane. The fundamental differences in fuel crossover for positive and negative electroosmotic drag coefficients are discussed. It is found that ethanol crossover is significantly reduced upon using an alkaline anion exchange membrane instead of a proton exchange membrane, especially at current densities higher than 500 A m

  6. A novel anion exchange membrane from polystyrene (ethylene butylene) polystyrene: Synthesis and characterization

    Energy Technology Data Exchange (ETDEWEB)

    Vinodh, Rajangam; Ilakkiya, Arjunan; Elamathi, Swaminathan [Department of Chemistry, Anna University Chennai, Sardar Patel Road, Chennai 600025, Tamil Nadu (India); Sangeetha, Dharmalingam, E-mail: sangeetha@annauniv.ed [Department of Chemistry, Anna University Chennai, Sardar Patel Road, Chennai 600025, Tamil Nadu (India)

    2010-02-25

    We look forward for an eco-friendly hydrocarbon polymer with higher molecular weight for the preparation of an anion exchange membrane. Polystyrene ethylene butylene polystyrene (PSEBS) was chosen as the polymer matrix. The anion exchange membrane was prepared from PSEBS tri-block co-polymer and then the properties were characterized for alkaline fuel cell application. The preparation of anion exchange polymer involved two steps namely chloromethylation and quaternization. The anion exchange membrane with high conductivity has been prepared by introducing quaternary ammonium groups in to the polymer. Finally, the membrane was prepared using solution casting method. The solution casting method yields highly hydrophilic membranes with uniform structure that were suitable for electrochemical applications. The efficiency of the entrapment was monitored by swelling ratio, chemical stability and ion exchange measurement. The characteristic structural properties of the membrane were investigated by FT-IR spectroscopy and {sup 1}H NMR spectroscopy. The thermal stability of the membrane was characterized by TGA, DSC and DMA (dynamic mechanical analysis). The prepared uniform electrolyte membrane in this study has high thermal and chemical stability. The surface morphology and elemental composition of the quaternized PSEBS was determined by SEM-EDXA techniques, respectively. The measured hydroxyl ion conductivity of the synthesized alkaline PSEBS polymer electrolyte membrane showed ionic conductivity in the range of 10{sup -3} S/cm in deionized water at room temperature. It was found that the substitution provided a flexible, chemically and thermally stable membrane. Hence, the membrane will have potential application in the alkaline fuel cell.

  7. Selective Interaction of a Cationic Polyfluorene with Model Lipid Membranes: Anionic versus Zwitterionic Lipids

    Directory of Open Access Journals (Sweden)

    Zehra Kahveci

    2014-03-01

    Full Text Available This paper explores the interaction mechanism between the conjugated polyelectrolyte {[9,9-bis(6'-N,N,N-trimethylammoniumhexyl]fluorene-phenylene}bromide (HTMA-PFP and model lipid membranes. The study was carried out using different biophysical techniques, mainly fluorescence spectroscopy and microscopy. Results show that despite the preferential interaction of HTMA-PFP with anionic lipids, HTMA-PFP shows affinity for zwitterionic lipids; although the interaction mechanism is different as well as HTMA-PFP’s final membrane location. Whilst the polyelectrolyte is embedded within the lipid bilayer in the anionic membrane, it remains close to the surface, forming aggregates that are sensitive to the physical state of the lipid bilayer in the zwitterionic system. The different interaction mechanism is reflected in the polyelectrolyte fluorescence spectrum, since the maximum shifts to longer wavelengths in the zwitterionic system. The intrinsic fluorescence of HTMA-PFP was used to visualize the interaction between polymer and vesicles via fluorescence microscopy, thanks to its high quantum yield and photostability. This technique allows the selectivity of the polyelectrolyte and higher affinity for anionic membranes to be observed. The results confirmed the appropriateness of using HTMA-PFP as a membrane fluorescent marker and suggest that, given its different behaviour towards anionic and zwitterionic membranes, HTMA-PFP could be used for selective recognition and imaging of bacteria over mammalian cells.

  8. Ultrathin self-assembled anionic polymer membranes for superfast size-selective separation

    Science.gov (United States)

    Deng, Chao; Zhang, Qiu Gen; Han, Guang Lu; Gong, Yi; Zhu, Ai Mei; Liu, Qing Lin

    2013-10-01

    Nanoporous membranes with superior separation performance have become more crucial with increasing concerns in functional nanomaterials. Here novel ultrahigh permeable nanoporous membranes have been fabricated on macroporous supports by self-assembly of anionic polymer on copper hydroxide nanostrand templates in organic solution. This facile approach has a great potential for the fabrication of ultrathin anionic polymer membranes as a general method. The as-fabricated self-assembled membranes have a mean pore size of 5-12 nm and an adjustable thickness as low as 85 nm. They allow superfast permeation of water, and exhibit excellent size-selective separation properties and good fouling resistance for negatively-charged solutes during filtration. The 85 nm thick membrane has an ultrahigh water flux (3306 l m-2 h-1 bar-1) that is an order of magnitude larger than commercial membranes, and can highly efficiently separate 5 and 15 nm gold nanoparticles from their mixtures. The newly developed nanoporous membranes have a wide application in separation and purification of biomacromolecules and nanoparticles.Nanoporous membranes with superior separation performance have become more crucial with increasing concerns in functional nanomaterials. Here novel ultrahigh permeable nanoporous membranes have been fabricated on macroporous supports by self-assembly of anionic polymer on copper hydroxide nanostrand templates in organic solution. This facile approach has a great potential for the fabrication of ultrathin anionic polymer membranes as a general method. The as-fabricated self-assembled membranes have a mean pore size of 5-12 nm and an adjustable thickness as low as 85 nm. They allow superfast permeation of water, and exhibit excellent size-selective separation properties and good fouling resistance for negatively-charged solutes during filtration. The 85 nm thick membrane has an ultrahigh water flux (3306 l m-2 h-1 bar-1) that is an order of magnitude larger than

  9. Removal of Congo Red from Aqueous Solution by Anion Exchange Membrane (EBTAC): Adsorption Kinetics and Themodynamics

    Science.gov (United States)

    Khan, Muhammad Imran; Akhtar, Shahbaz; Zafar, Shagufta; Shaheen, Aqeela; Khan, Muhammad Ali; Luque, Rafael; ur Rehman, Aziz

    2015-01-01

    The adsorption behavior of anionic dye congo red (CR) from aqueous solutions using an anion exchange membrane (EBTAC) has been investigated at room temperature. The effect of several factors including contact time, membrane dosage, ionic strength and temperature were studied. Kinetic models, namely pseudo-first-order and pseudo-second-order, liquid film diffusion and Elovich models as well as Bangham and modified freundlich Equations, were employed to evaluate the experimental results. Parameters such as adsorption capacities, rate constant and related correlation coefficients for every model were calculated and discussed. The adsorption of CR on anion exchange membranes followed pseudo-second-order Kinetics. Thermodynamic parameters, namely changes in Gibbs free energy (∆G°), enthalpy (∆H°) and entropy (∆S°) were calculated for the adsorption of congo red, indicating an exothermic process. PMID:28793430

  10. Fabrication of Electrospun Polyamide-6/Chitosan Nanofibrous Membrane toward Anionic Dyes Removal

    Directory of Open Access Journals (Sweden)

    Mozhdeh Ghani

    2014-01-01

    Full Text Available Nanofibrous filter media of polyamide-6/chitosan were fabricated by electrospinning onto a satin fabric substrate and characterized by scanning electron microscopy (SEM, Fourier transform infrared spectroscopy (FTIR, and water contact angle (WCA. Anionic dye removal capability of the filter was investigated for Solophenyl Red 3BL and Polar Yellow GN, respectively, as acidic and direct dyes were investigated with respect to solution parameters (pH and initial dye concentration and membrane parameters (electrospinning time and chitosan ratio through filtration system. Experiments were designed using response surface methodology (RSM based on five-level central composite design (CCD with four parameters to maximize removal efficiency of the filter media. Moreover, the effect of parameters and their likely interactions on dye removal were investigated by mathematically developed models. The optimum values for solution pH, initial dye concentration, electrospinning time, and chitosan ratio were predicted to be 5, 50 mg/L, 4 hr, 30% and 5, 100 mg/L, 4 hr, 10%, respectively, for achieving 96% and 95% removal of Solophenyl Red 3BL and Polar Yellow GN. Evaluation of the estimation capability of applied models revealed that the models have a good agreement with experimental values. This study demonstrated that polyamide-6/chitosan nanofibrous membrane has an enormous applicable potential in dye removal from aqueous solutions.

  11. Preparation of high-capacity, weak anion-exchange membranes by surface-initiated atom transfer radical polymerization of poly(glycidyl methacrylate) and subsequent derivatization with diethylamine

    International Nuclear Information System (INIS)

    Qian, Xiaolei; Fan, Hua; Wang, Chaozhan; Wei, Yinmao

    2013-01-01

    Ion-exchange membrane is of importance for the development of membrane chromatography. In this work, a high-capacity anion-exchange membrane was prepared by grafting of glycidyl methacrylate (GMA) onto the surface of regenerated cellulose (RC) membranes via surface-initiated atom transfer radical polymerization (SI-ATRP) and subsequent derivatization with diethylamine. Attenuated total reflectance Fourier-transform infrared (ATR-FTIR), X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM) were used to characterize changes in the chemical functionality, surface topography and pore morphology of the modified membranes. The static capacity of the prepared anion-exchange membrane was evaluated with bovine serum albumin (BSA) as a model protein. The results indicated that the anion-exchange membrane which could reach a maximum capacity of 96 mg/mL for static adsorption possesses a higher adsorption capacity, and the adsorption capacity increases with the polymerization time. The effect of pH and salt concentration confirmed that the adsorption of BSA followed ion-exchange mechanism. The established method would have potential application in the preparation of anion-exchange membrane.

  12. DEVELOPMENT AND CHARACTERIZATION OF POLYVINYLIDENE FLUORIDE - IMIDAZOLIUM FUNCTIONALIZED POLYSULFONE BLEND ANION EXCHANGE MEMBRANE

    Directory of Open Access Journals (Sweden)

    S. VELU

    2015-09-01

    Full Text Available Anion exchange membrane (AEM is one of the core components of an alkaline fuel cell influencing the fuel cell’s performance, durability and stability. Out of the many anion exchange membranes reported so far, imidazolium functionalized polysulfone (PSf-ImOH membrane has been identified to have high hydroxide ionic conductivity, reaching up to 50 mS cm-1 at 20oC. However, at high levels of ion exchange capacity, the membrane’s water uptake and swelling ratio increases significantly with temperature thus destabilizing it and making it unfit for potential use in high temperature alkaline fuel cells. This limitation of PSf-ImOH membranes has been overcome by blending it with polyvinylidene fluoride (PVDF polymer, which is a thermally stable and highly hydrophobic polymer. PSf-ImOH membrane with a high degree of chloromethylation (180% was synthesized and blended with PVDF at different weight ratios (PVDF / PSf-ImOH: 30/70, 50/50 and 70/30 to create a series of novel anion exchange membranes. The prepared membranes were characterized to study their structure, water uptake, swelling ratio, solubility in low boiling water soluble solvents, thermal stability, ion exchange capacity (IEC and ionic conductivity (IC at different temperatures. The 70% PVDF blend membrane demonstrated the better performance in terms of IEC, IC and water uptake properties compared to other membranes. Comparative studies on the water uptake and IC variation between the 70% PVDF blend membrane and pure PSfImOH membrane (having the same IEC as that of the blend membrane, clearly indicated the superiority and the promising use of the blend membrane in alkaline fuel cell especially for high temperature working condition.

  13. Design of Anion Exchange Membranes and Electrodialysis Studies for Water Desalination

    Directory of Open Access Journals (Sweden)

    Muhammad Imran Khan

    2016-05-01

    Full Text Available Anion exchange membranes are highly versatile and nowadays have many applications, ranging from water treatment to sensing materials. The preparation of anion exchange membranes (AEMs from brominated poly(2,6-dimethyl-1,6-phenylene oxide (BPPO and methyl(diphenylphosphine (MDPP for electrodialysis was performed. The physiochemical properties and electrochemical performance of fabricated membranes can be measured by changing MDPP contents in the membrane matrix. The influence of a quaternary phosphonium group associated with the removal of NaCl from water is discussed. The prepared membranes have ion exchange capacities (IEC 1.09–1.52 mmol/g, water uptake (WR 17.14%–21.77%, linear expansion ratio (LER 7.96%–11.86%, tensile strength (TS 16.66–23.97 MPa and elongation at break (Eb 485.57%–647.98%. The prepared anion exchange membranes were employed for the electrodialytic removal of 0.1 M NaCl aqueous solution at a constant applied voltage. It is found that the reported membranes could be the promising candidate for NaCl removal via electrodialysis.

  14. Investigation of Electrochemical and Morphological Properties of Mixed Matrix Polysulfone-Silica Anion Exchange Membrane

    Directory of Open Access Journals (Sweden)

    Khoiruddin

    2016-02-01

    Full Text Available Mixed matrix anion exchange membranes (AEMs were synthesized using dry-wet phase inversion. The casting solutions were prepared by dispersing finely ground anion-exchange resin particles in N,N-dimethylacetamide (DMAc solutions of polysulfone (PSf. Subsequently, nanosilica particles were introduced into the membranes. The results show that evaporation time (tev and solution composition contributed to membrane properties formation. A longer tev produces membranes with reduced void fraction inside the membranes, thus the amount of water adsorbed and membrane conductivity are reduced. Meanwhile, the permselectivity was improved by increasing tev, since a longer tev produces membranes with a narrower channel for ion migration and more effective Donnan exclusion. The incorporation of 0.5 %-wt nanosilica particles into the polymer matrix led to conductivity improvement (from 2.27 to 3.41 mS.cm-1. This may be associated with additional pathway formation by hydroxyl groups on the silica surface that entraps water and assists ion migration. However, at further silica loading (1.0 and 1.5 %-wt, these properties decreased (to 1.9 and 1.4 mS.cm-1 respectively, which attributed to inaccessibility of ion-exchange functional groups due to membrane compactness. It was found from the results that nanosilica contributes to membrane formation (increases casting solution viscosity then reduces void fraction and membrane functional group addition (provides hydroxyl groups.

  15. DNA release from lipoplexes by anionic lipids: correlation with lipid mesomorphism, interfacial curvature, and membrane fusion

    Energy Technology Data Exchange (ETDEWEB)

    Tarahovsky, Yury S.; Koynova, Rumiana; MacDonald, Robert C. (Northwestern)

    2010-01-18

    DNA release from lipoplexes is an essential step during lipofection and is probably a result of charge neutralization by cellular anionic lipids. As a model system to test this possibility, fluorescence resonance energy transfer between DNA and lipid covalently labeled with Cy3 and BODIPY, respectively, was used to monitor the release of DNA from lipid surfaces induced by anionic liposomes. The separation of DNA from lipid measured this way was considerably slower and less complete than that estimated with noncovalently labeled DNA, and depends on the lipid composition of both lipoplexes and anionic liposomes. This result was confirmed by centrifugal separation of released DNA and lipid. X-ray diffraction revealed a clear correlation of the DNA release capacity of the anionic lipids with the interfacial curvature of the mesomorphic structures developed when the anionic and cationic liposomes were mixed. DNA release also correlated with the rate of fusion of anionic liposomes with lipoplexes. It is concluded that the tendency to fuse and the phase preference of the mixed lipid membranes are key factors for the rate and extent of DNA release. The approach presented emphasizes the importance of the lipid composition of both lipoplexes and target membranes and suggests optimal transfection may be obtained by tailoring lipoplex composition to the lipid composition of target cells.

  16. Carbonate and Bicarbonate Ion Transport in Alkaline Anion Exchange Membranes

    Science.gov (United States)

    2013-06-25

    comparable assumptions, a similar equation can be derived starting with the Nernst -Planck equation . σ = ∑ σi = ∑ F2z2i RT (ε− ε0)q D0i 1 + δi Ci [1] Using Eq...an appropriate ion-membrane diffusion coefficient. Finally, an equation derived from the dusty fluid model can be used to calculate the ionic...Finally, an equation derived from the dusty fluid model can be used to calculate the ionic conductivity of the membrane in different counter ion forms

  17. The importance of OH − transport through anion exchange membrane in microbial electrolysis cells

    KAUST Repository

    Ye, Yaoli; Logan, Bruce

    2018-01-01

    In two-chamber microbial electrolysis cells (MECs) with anion exchange membranes (AEMs), a phosphate buffer solution (PBS) is typically used to avoid increases in catholyte pH as Nernst equation calculations indicate that high pHs adversely impact

  18. Distribution of anionic sites in Bruch's membrane of the rabbit eye.

    Science.gov (United States)

    Essner, E; Pino, R M

    1982-06-01

    The organization of anionic (negatively charged) sites in Bruch's membrane of the rabbit eye at various stages of postnatal development was studied using the cationic polymer, polyethyleneimine (PEI). PEI-positive sites were demonstrable as rows of particles (diameter ca. 18 nm) located at intervals along either side of the basal laminae of the retinal pigment epithelium and choriocapillary endothelium. In tangential sections through Bruch's membrane, stained particles appeared to be arranged in a semi-regular, lattice-like pattern in which the sites were separated from each other by an interval of approximately 50 nm. PEI-positive particles were also observed on collagen fibers where they were distributed at regular intervals along the length of the fiber. In tangential sections, collagen fibers formed a loosely packed meshwork in the central zone of Bruch's membrane. In addition, individual fibers were frequently oriented so that one end was located close to or within the substance of the basal laminae, a result suggesting that the anionic sites on these fibers might contribute to the network present in the basal laminae. The findings lend further support to the suggestion that anionic sites in Bruch's membrane may serve as a charge barrier which retards the movement of anionic molecules that are in transit from the choriocapillaris to the retinal pigment epithelium and outer neural retina.

  19. Determination of the ion-exchange capacity of anion-selective membranes

    Czech Academy of Sciences Publication Activity Database

    Karas, F.; Hnát, J.; Paidar, M.; Schauer, Jan; Bouzek, K.

    2014-01-01

    Roč. 39, č. 10 (2014), s. 5054-5062 ISSN 0360-3199 Institutional support: RVO:61389013 Keywords : ion-exchange capacity * anion-selective membranes * titration Subject RIV: CD - Macromolecular Chemistry Impact factor: 3.313, year: 2014

  20. Novel fluoropolymer anion exchange membranes for alkaline direct methanol fuel cells.

    Science.gov (United States)

    Zhang, Yanmei; Fang, Jun; Wu, Yongbin; Xu, Hankun; Chi, Xianjun; Li, Wei; Yang, Yixu; Yan, Ge; Zhuang, Yongze

    2012-09-01

    A series of novel fluoropolymer anion exchange membranes based on the copolymer of vinylbenzyl chloride, butyl methacrylate, and hexafluorobutyl methacrylate has been prepared. Fourier transform infrared (FT-IR) spectroscopy and elemental analysis techniques are used to study the chemical structure and chemical composition of the membranes. The water uptake, ion-exchange capacity (IEC), conductivity, methanol permeability, and chemical stability of the membranes are also determined. The membranes exhibit high anionic conductivity in deionized water at 65 °C ranging from 3.86×10(-2) S cm(-1) to 4.36×10(-2) S cm(-1). The methanol permeability coefficients of the membranes are in the range of 4.21-5.80×10(-8) cm(2) s(-1) at 65 °C. The novel membranes also show good chemical and thermal stability. An open-circuit voltage of 0.7 V and a maximum power density of 53.2 mW cm(-2) of alkaline direct methanol fuel cell (ADMFC) with the membrane C, 1 M methanol, 1 M NaOH, and humidified oxygen are achieved at 65 °C. Therefore, these membranes have great potential for applications in fuel cell systems. Copyright © 2012 Elsevier Inc. All rights reserved.

  1. A series of poly(butylimidazolium) ionic liquid functionalized copolymers for anion exchange membranes

    Science.gov (United States)

    Ouadah, Amina; Xu, Hulin; Luo, Tianwei; Gao, Shuitao; Wang, Xing; Fang, Zhou; Jing, Chaojun; Zhu, Changjin

    2017-12-01

    A new series of ionic liquid functionalized copolymers for anion exchange membranes (AEM) is prepared. Poly(butylvinylimidazolium)(b-VIB) is copolymerized with para-methyl styrene (p-MS) by the radical polymerization formed block copolymers b-VIB/p-MS, which is crosslinked with poly(diphenylether bibenzimidazole) (DPEBI) providing the desired materials b-VIB/p-MS/DPEBI. Structures are characterized via H1NMR, FTIR spectra and elemental analysis. The b-VIB blocks offer the anion conduction function while DPEBI moieties contribute to enhancing other properties. The prepared membranes display chloride conductivity as high as 19.5 mS/cm at 25 °C and 69.2 mS/cm at 100 °C-higher than that of the commercial membrane tokuyuama A201-. Their hydroxide conductivity reaches 35.7 Scm-1 at 25 °C and 73.1 Scm-1 at 100 °C. The membranes showed a linear Arrhenius behavior in the anion conduction, low activation energies and distinguished nanophase separation of hydrophilic/hydrophobic regions by the transmission electron microscopy (TEM) studies. Thermal investigations using TGA and DSC confirm that the membranes are stable up to 250 °C. Particularly, drastically alkaline stability due to no decrease in the hydroxide conductivity after 168 h of treatment with 2M KOH.

  2. Mechanical Characterization of Anion Exchange Membranes Under Controlled Environmental Conditions

    Science.gov (United States)

    2015-05-11

    little market penetration has been achieved. Proton exchange membrane fuel cells ( PEMFC ) have struggled primarily due to high cost, driven by the use...and requirements for Pt, Pt-alloy, and non-Pt oxygen reduction catalysts for PEMFCs , Appl. Catal. B Environ. 56 (2005) 9–35. doi:10.1016/j.apcatb...resins for PEMFCs , Electrochim. Acta. 50 (2004) 571–575. doi:10.1016/j.electacta.2004.01.133. [89] S. Bhadra, N.H. Kim, J.S. Choi, K.Y. Rhee, J.H. Lee

  3. A procedure for reducing the concentration of hydrogen ions in acid anionic eluate and equipment therefore

    International Nuclear Information System (INIS)

    Parobek, P.; Baloun, S.; Plevac, S.

    1989-01-01

    The method is described of reducing the concentration of hydrogen ions in acid anionic eluate produced in the separation of uranium or other metals, in which anion exchanger elution, precipitation, filtration and precipitate and anion exchanger washing are used. The technological line for such elution comprises at least one ion exchange column and at least one container. They together form the first and the second stages of preparation of the acid anion elution solution, the sorption-elution separation of hydrogen ions on an cation exchanger being inserted between them. The preparation of the solution is divide into two stages. In the first stage, the acid and part of the solution for the preparation of the acid anion elution solution are supplied. The resulting enriched acid elution solution is fe onto the cation exchanger where the hydrogen ion concentration i reduced. It is then carried into the second stage where it is mixed with the remaining part of the solution. (B.S.)

  4. Determination of Anionic Detergent Concentration of Karasu Stream in Sinop (Turkey

    Directory of Open Access Journals (Sweden)

    Ayşe Gündoğdu

    2018-02-01

    Full Text Available The study was achieved between May 2014 and April 2015 at the Karasu Creek located in the province of Sinop. It was conducted to determine anionic detergent pollution and some physicochemical properties (pH, temperature, conductivity, salinity, dissolved oxygen, total hardness, chemical oxygen demand, phosphate PO4-3, total nitrogen. The anionic detergent concentration of the stations was determined on a monthly basis. Seasonally averaged values of the anionic detergent was measured as the highest value in the autumn season. The lowest values of anionic detergent were found in stations in winter and spring. The increase in the concentration of anionic detergent is caused by population growth in residential areas, increased agricultural activities and rains, and that chemicals move to riverbed from terrestrial areas with rain water.

  5. Salt Concentration Differences Alter Membrane Resistance in Reverse Electrodialysis Stacks

    KAUST Repository

    Geise, Geoffrey M.; Curtis, Andrew J.; Hatzell, Marta C.; Hickner, Michael A.; Logan, Bruce E.

    2014-01-01

    Membrane ionic resistance is usually measured by immersing the membrane in a salt solution at a single, fixed concentration. While salt concentration is known to affect membrane resistance when the same concentration is used on both sides

  6. Filterability and Sludge Concentration in Membrane Bioreactors

    NARCIS (Netherlands)

    Lousada-Ferreira, M.

    2011-01-01

    The Thesis entitled “Filterability and Sludge Concentration in Membrane Bioreactors” aims at explaining the relation between Mixed Liquid Suspended Solids (MLSS) concentration, the amount of solids in the wastewater being treated, also designated as sludge, and filterability, being the ability of

  7. Anion-exchange membranes derived from quaternized polysulfone and exfoliated layered double hydroxide for fuel cells

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Wan; Liang, Na; Peng, Pai; Qu, Rong; Chen, Dongzhi; Zhang, Hongwei, E-mail: hanqiujiang@163.com

    2017-02-15

    Layered double hydroxides (LDH) are prepared by controlling urea assisted homogeneous precipitation conditions. Morphology and crystallinity of LDHs are confirmed by X-ray diffraction and scanning electron microscope. After LDHs are incorporated into quaternized polysulfone membranes, transmission electron microscope is used to observe the exfoliated morphology of LDH sheets in the membranes. The properties of the nanocomposite membranes, including water uptake, swelling ratio, mechanical property and ionic conductivity are investigated. The nanocomposite membrane containing 5% LDH sheets shows more balanced performances, exhibiting an ionic conductivity of 2.36×10{sup −2} S cm{sup −1} at 60 °C. - Graphical abstract: Anion-exchange membrane based on quaternized polysulfone and exfoliated layered double hydroxide is optically transparent and has good ionic properties.

  8. Ammonium Bicarbonate Transport in Anion Exchange Membranes for Salinity Gradient Energy

    KAUST Repository

    Geise, Geoffrey M.

    2013-09-17

    Many salinity gradient energy technologies such as reverse electrodialysis (RED) rely on highly selective anion transport through polymeric anion exchange membranes. While there is considerable interest in using thermolytic solutions such as ammonium bicarbonate (AmB) in RED processes for closed-loop conversion of heat energy to electricity, little is known about membrane performance in this electrolyte. The resistances of two commercially available cation exchange membranes in AmB were lower than their resistances in NaCl. However, the resistances of commercially available anion exchange membranes (AEMs) were much larger in AmB than in NaCl, which would adversely affect energy recovery. The properties of a series of quaternary ammonium-functionalized poly(phenylene oxide) and Radel-based AEMs were therefore examined to understand the reasons for increased resistance in AmB to overcome this performance penalty due to the lower mobility of bicarbonate, 4.59 × 10-4 cm2/(V s), compared to chloride, 7.90 × 10-4 cm2/(V s) (the dilute aqueous solution mobility ratio of HCO3 - to Cl- is 0.58). Most membrane resistances were generally consistent with the dilute solution mobilities of the anions. For a few key samples, however, increased water uptake in AmB solution reduced the ionic resistance of the polymer compared to its resistance in NaCl solution. This increased water uptake was attributed to the greater hydration of the bicarbonate ion compared to the chloride ion. The increased resistance due to the use of bicarbonate as opposed to chloride ions in AEMs can therefore be mitigated by designing polymers that swell more in AmB compared to NaCl solutions, enabling more efficient energy recovery using AmB thermolytic solutions in RED. © 2013 American Chemical Society.

  9. Ammonium Bicarbonate Transport in Anion Exchange Membranes for Salinity Gradient Energy

    KAUST Repository

    Geise, Geoffrey M.; Hickner, Michael A.; Logan, Bruce E.

    2013-01-01

    Many salinity gradient energy technologies such as reverse electrodialysis (RED) rely on highly selective anion transport through polymeric anion exchange membranes. While there is considerable interest in using thermolytic solutions such as ammonium bicarbonate (AmB) in RED processes for closed-loop conversion of heat energy to electricity, little is known about membrane performance in this electrolyte. The resistances of two commercially available cation exchange membranes in AmB were lower than their resistances in NaCl. However, the resistances of commercially available anion exchange membranes (AEMs) were much larger in AmB than in NaCl, which would adversely affect energy recovery. The properties of a series of quaternary ammonium-functionalized poly(phenylene oxide) and Radel-based AEMs were therefore examined to understand the reasons for increased resistance in AmB to overcome this performance penalty due to the lower mobility of bicarbonate, 4.59 × 10-4 cm2/(V s), compared to chloride, 7.90 × 10-4 cm2/(V s) (the dilute aqueous solution mobility ratio of HCO3 - to Cl- is 0.58). Most membrane resistances were generally consistent with the dilute solution mobilities of the anions. For a few key samples, however, increased water uptake in AmB solution reduced the ionic resistance of the polymer compared to its resistance in NaCl solution. This increased water uptake was attributed to the greater hydration of the bicarbonate ion compared to the chloride ion. The increased resistance due to the use of bicarbonate as opposed to chloride ions in AEMs can therefore be mitigated by designing polymers that swell more in AmB compared to NaCl solutions, enabling more efficient energy recovery using AmB thermolytic solutions in RED. © 2013 American Chemical Society.

  10. Preparation of a surface-grafted imprinted ceramic membrane for selective separation of molybdate anion from water solutions.

    Science.gov (United States)

    Zeng, Jianxian; Dong, Zhihui; Zhang, Zhe; Liu, Yuan

    2017-07-05

    A surface-grafted imprinted ceramic membrane (IIP-PVI/CM) for recognizing molybdate (Mo(VI)) anion was prepared by surface-initiated graft-polymerization. Firstly, raw alumina ceramic membrane (CM) was deposited with SiO 2 active layer by situ hydrolysis deposition method. Subsequently, γ-methacryloxy propyl trimethoxyl silane (MPS) was used as a coupling agent to introduce double bonds onto the SiO 2 layer (MPS-CM). Then, 1-vinylimidazole (VI) was employed as a functional monomer to graft-polymerization onto the MPS-CM (PVI-CM). During the graft-polymerization, the influence factors of grafting degree of PVI were investigated in detail. Under optimum conditions (monomer concentration 20wt%, temperature 70°C, initiator amount 1.1wt% and reaction time 8h), the grafting degree of 20.39g/100g was obtained. Further, Mo(VI) anion was used as a template to imprint in the PVI-CM by employing 1,6-dibromohexane as a cross-linking agent, and then Mo(VI) was removed, obtaining the IIP-PVI/CM with many imprinted cavities for Mo(VI). Thereafter, static adsorption and dynamic separation properties of IIP-PVI/CM for Mo(VI) were studied. Results indicate that IIP-PVI/CM shows a specific selectivity for Mo(VI) with the adsorption capacity of 0.69mmol/100g, and the selectivity coefficient of IIP-PVI/CM is 7.48 for molybdate to tungstate anions. During the dynamic separation, IIP-PVI/CM has also good selectivity for separation of Mo(VI) and W(VI) anions. Copyright © 2017 Elsevier B.V. All rights reserved.

  11. Effect of CO2 absorption on ion and water mobility in an anion exchange membrane

    Science.gov (United States)

    Peng, Jing; Roy, Asa L.; Greenbaum, Steve G.; Zawodzinski, Thomas A.

    2018-03-01

    We report the measured water uptake, density, ionic conductivity and water transport properties in Tokuyama A201 membrane in OH-, HCO3- and Cl- forms. The water uptake of the AEM varies with anion type in the order λ(OH-) > λ(HCO3-) > λ(Cl-) for samples equilibrated with the same water vapor activity (aw). The conductivity of the AEM is reduced by absorption of CO2. Pulsed-field gradient nuclear magnetic resonance (PFG-NMR) measurements were utilized to characterize the diffusivity of water and HCO3- ion. The anion diffusion coefficient and membrane conductivity are used to probe the applicability of the Nernst-Einstein equation in these AEMs.

  12. Imidazolium-Based Polymeric Materials as Alkaline Anion-Exchange Fuel Cell Membranes

    Science.gov (United States)

    Narayan, Sri R.; Yen, Shiao-Ping S.; Reddy, Prakash V.; Nair, Nanditha

    2012-01-01

    Polymer electrolyte membranes that conduct hydroxide ions have potential use in fuel cells. A variety of polystyrene-based quaternary ammonium hydroxides have been reported as anion exchange fuel cell membranes. However, the hydrolytic stability and conductivity of the commercially available membranes are not adequate to meet the requirements of fuel cell applications. When compared with commercially available membranes, polystyrene-imidazolium alkaline membrane electrolytes are more stable and more highly conducting. At the time of this reporting, this has been the first such usage for imidazolium-based polymeric materials for fuel cells. Imidazolium salts are known to be electrochemically stable over wide potential ranges. By controlling the relative ratio of imidazolium groups in polystyrene-imidazolium salts, their physiochemical properties could be modulated. Alkaline anion exchange membranes based on polystyrene-imidazolium hydroxide materials have been developed. The first step was to synthesize the poly(styrene-co-(1-((4-vinyl)methyl)-3- methylimidazolium) chloride through a free-radical polymerization. Casting of this material followed by in situ treatment of the membranes with sodium hydroxide solutions provided the corresponding hydroxide salts. Various ratios of the monomers 4-chloromoethylvinylbenzine (CMVB) and vinylbenzine (VB) provided various compositions of the polymer. The preferred material, due to the relative ease of casting the film, and its relatively low hygroscopic nature, was a 2:1 ratio of CMVB to VB. Testing confirmed that at room temperature, the new membranes outperformed commercially available membranes by a large margin. With fuel cells now in use at NASA and in transportation, and with defense potential, any improvement to fuel cell efficiency is a significant development.

  13. Plasma-polymerized alkaline anion-exchange membrane: Synthesis and structure characterization

    International Nuclear Information System (INIS)

    Hu Jue; Meng Yuedong; Zhang Chengxu; Fang Shidong

    2011-01-01

    After-glow discharge plasma polymerization was developed for alkaline anion-exchange membranes synthesis using vinylbenzyl chloride as monomer. X-ray photoelectron spectroscopy and attenuated total reflection Fourier transform infrared spectroscopy were used to characterize the chemical structure properties of plasma-polymerized membranes. Ion-exchange capacities of quaternized poly(vinylbenzyl chloride) (QPVBC) membranes were measured to evaluate their capability of hydroxyl ion transport. A mechanism of plasma polymerization using VBC as monomer that accounts for the competitive effects of free radicals polymerization and plasma ablation in the plasma polymerization process was proposed. Our results indicate that plasma discharge power influences the contents of functional groups and the structure of the plasma polymer membranes, which attribute to the coactions of polymerization and ablation. The properties of uniform morphology, good adhesion to the substrate, high thermal stability and satisfying anion conduction level suggest the potential application of QPVBC membrane deposited at discharge power of 20 W in alkaline direct methanol fuel cells.

  14. Preparation and performance evaluation of novel alkaline stable anion exchange membranes

    Science.gov (United States)

    Irfan, Muhammad; Bakangura, Erigene; Afsar, Noor Ul; Hossain, Md. Masem; Ran, Jin; Xu, Tongwen

    2017-07-01

    Novel alkaline stable anion exchange membranes are prepared from various amounts of N-methyl dipicolylamine (MDPA) and brominated poly (2,6-dimethyl-1,4-phenylene oxide) (BPPO). The dipicolylamine and MDPA are synthesized through condensation reaction and confirmed by 1H NMR spectroscopy. The morphologies of prepared membranes are investigated by atomic force microscopy (AFM), fourier transform infrared spectroscopy (FTIR), 1H NMR spectroscopy and scanning electron microscopy (SEM). The electrochemical and physical properties of AEMs are tested comprising water uptake (WU), ion exchange capacity (IEC), alkaline stability, linear expansion ratio (LER), thermal stability and mechanical stability. The obtained hydroxide conductivity of MDPA-4 is 66.5 mS/cm at 80 °C. The MDPA-4 membrane shows good alkaline stability, high hydroxide conductivity, low methanol permeability (3.43 × 10-7 cm2/s), higher selectivity (8.26 × 107 mS s/cm3), less water uptake (41.1%) and lower linear expansion (11.1%) despite of high IEC value (1.62 mmol/g). The results prove that MDPA membranes have great potential application in anion exchange membrane fuel cell.

  15. Heterogeneous anion-selective membranes: Influence of a water-soluble component in the membrane on the morphology and ionic conductivity

    Czech Academy of Sciences Publication Activity Database

    Schauer, Jan; Hnát, J.; Brožová, Libuše; Žitka, Jan; Bouzek, K.

    401/402, 15 May (2012), s. 83-88 ISSN 0376-7388 R&D Projects: GA MŠk(CZ) 7E08005 EU Projects: European Commission(XE) 212903 - WELTEMP Institutional research plan: CEZ:AV0Z40500505 Keywords : heterogeneous membrane * anion-exchange membrane * membrane morphology Subject RIV: CD - Macromolecular Chemistry Impact factor: 4.093, year: 2012

  16. Anion- or Cation-Exchange Membranes for NaBH4/H2O2 Fuel Cells?

    Science.gov (United States)

    Sljukić, Biljana; Morais, Ana L; Santos, Diogo M F; Sequeira, César A C

    2012-07-19

    Direct borohydride fuel cells (DBFC), which operate on sodium borohydride (NaBH4) as the fuel, and hydrogen peroxide (H2O2) as the oxidant, are receiving increasing attention. This is due to their promising use as power sources for space and underwater applications, where air is not available and gas storage poses obvious problems. One key factor to improve the performance of DBFCs concerns the type of separator used. Both anion- and cation-exchange membranes may be considered as potential separators for DBFC. In the present paper, the effect of the membrane type on the performance of laboratory NaBH4/H2O2 fuel cells using Pt electrodes is studied at room temperature. Two commercial ion-exchange membranes from Membranes International Inc., an anion-exchange membrane (AMI-7001S) and a cation-exchange membrane (CMI-7000S), are tested as ionic separators for the DBFC. The membranes are compared directly by the observation and analysis of the corresponding DBFC's performance. Cell polarization, power density, stability, and durability tests are used in the membranes' evaluation. Energy densities and specific capacities are estimated. Most tests conducted, clearly indicate a superior performance of the cation-exchange membranes over the anion-exchange membrane. The two membranes are also compared with several other previously tested commercial membranes. For long term cell operation, these membranes seem to outperform the stability of the benchmark Nafion membranes but further studies are still required to improve their instantaneous power load.

  17. Crosslinked anion exchange membranes with primary diamine-based crosslinkers for vanadium redox flow battery application

    Science.gov (United States)

    Cha, Min Suc; Jeong, Hwan Yeop; Shin, Hee Young; Hong, Soo Hyun; Kim, Tae-Ho; Oh, Seong-Geun; Lee, Jang Yong; Hong, Young Taik

    2017-09-01

    A series of polysulfone-based crosslinked anion exchange membranes (AEMs) with primary diamine-based crosslinkers has been prepared via simple a crosslinking process as low-cost and durable membranes for vanadium redox flow batteries (VRFBs). Chloromethylated polysulfone is used as a precursor polymer for crosslinked AEMs (CAPSU-x) with different degrees of crosslinking. Among the developed AEMs, CAPSU-2.5 shows outstanding dimensional stability and anion (Cl-, SO42-, and OH-) conductivity. Moreover, CAPSU-2.5 exhibits much lower vanadium ion permeability (2.72 × 10-8 cm2 min-1) than Nafion 115 (2.88 × 10-6 cm2 min-1), which results in an excellent coulombic efficiency of 100%. The chemical and operational stabilities of the membranes have been investigated via ex situ soaking tests in 0.1 M VO2+ solution and in situ operation tests for 100 cycles, respectively. The excellent chemical, physical, and electrochemical properties of the CAPSU-2.5 membrane make it suitable for use in VRFBs.

  18. A green approach for preparing anion exchange membrane based on cardo polyetherketone powders

    Science.gov (United States)

    Hu, Jue; Zhang, Chengxu; Zhang, Xiaodong; Chen, Longwei; Jiang, Lin; Meng, Yuedong; Wang, Xiangke

    2014-12-01

    Anion exchange membranes (AEMs) have attracted great attention due to their irreplaceable role in platinum-free fuel cell applications. The majority of AEM preparations have been performed in two steps: the grafting of functional groups and quaternization. Here, we adopted a simpler, more eco-friendly approach for the first time to prepare AEMs by atmospheric-pressure plasma-grafting. This approach enables the direct introduction of anion exchange groups (benzyltrimethylammonium groups) into the polymer matrix, overcoming the need for toxic chloromethyl ether and quaternization reagents. Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy and 1H NMR spectroscopy results demonstrate that benzyltrimethylammonium groups have been successfully grafted into the cardo polyetherketone (PEK-C) matrix. Thermogravimetric analysis reveals that the plasma-grafting technique is a facile and non-destructive method able to improve the thermal stability of the polymer matrix due to the strong preservation of the PEK-C backbone structure and the cross-linking of the grafted side chains. The plasma-grafted PG-NOH membrane, which shows satisfactory alcohol resistance (ethanol permeability of 6.3 × 10-7 cm2 s-1), selectivity (1.2 × 104 S s cm-3), thermal stability (safely used below 130 °C), chemical stability, anion conductivity (7.7 mS cm-1 at 20 °C in deionized water) and mechanical properties is promising for the construction of high-performance fuel cells.

  19. QUANTITATIVE ANALYSIS OF RELATIONSHIP STRUCTURE AND ANIONIC SURFACTANT MICELLE CONCENTRATION CRITIC WITH SEMIEMPIRIS AM1

    Directory of Open Access Journals (Sweden)

    Eva Vaulina Yulistia Delsy

    2017-05-01

    Full Text Available This research determines the mathematical equation which calculate the Concentration Micelle Critic theoretical anionic surfactant. The research was conducted the depiction of each surfactant anionic three-dimensional compound models, followed by optimizing the model structure anionic surfactant by using AM1 calculation method. Furthermore the calculation of descriptors (QSPR method, then it was analyzed statistically using Multiple Linear Regression (MLR. The results of statistical calculations showed that to calculate the theoretical CMC anionic surfactant can use the QSPR equation: log CMC = 4.157+0.118qC1+7.698qC2+0.425α–0.010µ-0.129RD–0.138 log P+0.021BM–0.034Avdw, n = 100 ; r = 0.927 ; r2 = 0.860 ; SE = 0.352 ; F= 30.888 ; PRESS = 23.506

  20. Structure and dynamics of water and lipid molecules in charged anionic DMPG lipid bilayer membranes

    DEFF Research Database (Denmark)

    Rønnest, A. K.; Peters, Günther H.J.; Hansen, Flemming Yssing

    2016-01-01

    Molecular dynamics simulations have been used to investigate the influence of the valency of counter-ions on the structure of freestanding bilayer membranes of the anionic 1,2-dimyristoyl-sn-glycero-3-phosphoglycerol (DMPG) lipid at 310 K and 1 atm. At this temperature, the membrane is in the fluid...... compared to experimental results and used to determine an average diffusion constant for all water molecules in the system. On extrapolating the diffusion constants inferred experimentally to a temperature of 310 K, reasonable agreement with the simulations is obtained. However, the experiments do not have...... the sensitivity to confirm the diffusion of a small component of water bound to the lipids as found in the simulations. In addition, the orientation of the dipole moment of the water molecules has been determined as a function of their depth in the membrane. Previous indirect estimates of the electrostatic...

  1. Preparation of Two-Layer Anion-Exchange Poly(ethersulfone Based Membrane: Effect of Surface Modification

    Directory of Open Access Journals (Sweden)

    Lucie Zarybnicka

    2016-01-01

    Full Text Available The present work deals with the surface modification of a commercial microfiltration poly(ethersulfone membrane by graft polymerization technique. Poly(styrene-co-divinylbenzene-co-4-vinylbenzylchloride surface layer was covalently attached onto the poly(ethersulfone support layer to improve the membrane electrochemical properties. Followed by amination, a two-layer anion-exchange membrane was prepared. The effect of surface layer treatment using the extraction in various solvents on membrane morphological and electrochemical characteristics was studied. The membranes were tested from the point of view of water content, ion-exchange capacity, specific resistance, permselectivity, FT-IR spectroscopy, and SEM analysis. It was found that the two-layer anion-exchange membranes after the extraction using tetrahydrofuran or toluene exhibited smooth and porous surface layer, which resulted in improved ion-exchange capacity, electrical resistance, and permselectivity of the membranes.

  2. Quest for anionic MOF membranes: Continuous sod -ZMOF membrane with Co2 adsorption-driven selectivity

    KAUST Repository

    Almaythalony, Bassem; Shekhah, Osama; Swaidan, Raja; Belmabkhout, Youssef; Pinnau, Ingo; Eddaoudi, Mohamed

    2015-01-01

    We report the fabrication of the first continuous zeolite-like metal-organic framework (ZMOF) thin-film membrane. A pure phase sod-ZMOF, sodalite topology, membrane was grown and supported on a porous alumina substrate using a solvothermal

  3. The next generation fuel cells: anion exchange membrane fuel cells (AEMFC)

    International Nuclear Information System (INIS)

    Tauqir, A.; Zahoor, S.

    2013-01-01

    Many environmentally friendly alternatives (solar, wind, hydroelectric, and geothermal power) can only be used in particular environments. In contrast, fuel cells can have near-zero emissions, are quiet and efficient, and can work in any environment where the temperature is lower than the cell's operating temperature. Among various types of fuel cells, the AEMFC is the most recent one and has advantages such as excellent performance compared to other candidate fuel cells due to its active O/sub 2/ electrode kinetics and flexibility to use a wide range of electro-catalysts such as silver and nickels contrary to expensive one (Platinum) required for proton exchange membrane fuel cell (PEMFC). Anion exchange membrane (AEM) is a crucial part in AEMFC, determining durability and electrochemical performances of membrane electrode assembly (MEA). The role of an AEM is to conduct hydroxyl ions from cathode to anode. If this conduction is not sufficiently high and selective, the corresponding fuel cell will not find any practical application. One of the major problems associated with AEMFC is much lower conductivities of anion compare to proton conductivity in PEMFCs, even upon similar working condition. Thus AEMs is only practical, if it is chemically and mechanically stable against severe basic operation conditions and highly hydroxyl ions conductive. The conventional AEMs based on animated aliphatic and aromatic hydrocarbon or even fluorinated polymers tend to be attacked by hydroxyl ions, causing the degradation during operation is strongly basic conditions. (author)

  4. Structure and dynamics of water and lipid molecules in charged anionic DMPG lipid bilayer membranes

    International Nuclear Information System (INIS)

    Rønnest, A. K.; Peters, G. H.; Hansen, F. Y.; Taub, H.; Miskowiec, A.

    2016-01-01

    Molecular dynamics simulations have been used to investigate the influence of the valency of counter-ions on the structure of freestanding bilayer membranes of the anionic 1,2-dimyristoyl-sn-glycero-3-phosphoglycerol (DMPG) lipid at 310 K and 1 atm. At this temperature, the membrane is in the fluid phase with a monovalent counter-ion and in the gel phase with a divalent counter-ion. The diffusion constant of water as a function of its depth in the membrane has been determined from mean-square-displacement calculations. Also, calculated incoherent quasielastic neutron scattering functions have been compared to experimental results and used to determine an average diffusion constant for all water molecules in the system. On extrapolating the diffusion constants inferred experimentally to a temperature of 310 K, reasonable agreement with the simulations is obtained. However, the experiments do not have the sensitivity to confirm the diffusion of a small component of water bound to the lipids as found in the simulations. In addition, the orientation of the dipole moment of the water molecules has been determined as a function of their depth in the membrane. Previous indirect estimates of the electrostatic potential within phospholipid membranes imply an enormous electric field of 10 8 –10 9 V m −1 , which is likely to have great significance in controlling the conformation of translocating membrane proteins and in the transfer of ions and molecules across the membrane. We have calculated the membrane potential for DMPG bilayers and found ∼1 V (∼2 ⋅ 10 8 V m −1 ) when in the fluid phase with a monovalent counter-ion and ∼1.4 V (∼2.8 ⋅ 10 8 V m −1 ) when in the gel phase with a divalent counter-ion. The number of water molecules for a fully hydrated DMPG membrane has been estimated to be 9.7 molecules per lipid in the gel phase and 17.5 molecules in the fluid phase, considerably smaller than inferred experimentally for 1,2-dimyristoyl-sn-glycero-3

  5. Structure and dynamics of water and lipid molecules in charged anionic DMPG lipid bilayer membranes

    Energy Technology Data Exchange (ETDEWEB)

    Rønnest, A. K.; Peters, G. H.; Hansen, F. Y., E-mail: flemming@kemi.dtu.dk [Department of Chemistry, Technical University of Denmark, IK 207 DTU, DK-2800 Lyngby (Denmark); Taub, H.; Miskowiec, A. [Department of Physics and Astronomy and the University of Missouri Research Reactor,University of Missouri, Columbia, Missouri 65211 (United States)

    2016-04-14

    Molecular dynamics simulations have been used to investigate the influence of the valency of counter-ions on the structure of freestanding bilayer membranes of the anionic 1,2-dimyristoyl-sn-glycero-3-phosphoglycerol (DMPG) lipid at 310 K and 1 atm. At this temperature, the membrane is in the fluid phase with a monovalent counter-ion and in the gel phase with a divalent counter-ion. The diffusion constant of water as a function of its depth in the membrane has been determined from mean-square-displacement calculations. Also, calculated incoherent quasielastic neutron scattering functions have been compared to experimental results and used to determine an average diffusion constant for all water molecules in the system. On extrapolating the diffusion constants inferred experimentally to a temperature of 310 K, reasonable agreement with the simulations is obtained. However, the experiments do not have the sensitivity to confirm the diffusion of a small component of water bound to the lipids as found in the simulations. In addition, the orientation of the dipole moment of the water molecules has been determined as a function of their depth in the membrane. Previous indirect estimates of the electrostatic potential within phospholipid membranes imply an enormous electric field of 10{sup 8}–10{sup 9} V m{sup −1}, which is likely to have great significance in controlling the conformation of translocating membrane proteins and in the transfer of ions and molecules across the membrane. We have calculated the membrane potential for DMPG bilayers and found ∼1 V (∼2 ⋅ 10{sup 8} V m{sup −1}) when in the fluid phase with a monovalent counter-ion and ∼1.4 V (∼2.8 ⋅ 10{sup 8} V m{sup −1}) when in the gel phase with a divalent counter-ion. The number of water molecules for a fully hydrated DMPG membrane has been estimated to be 9.7 molecules per lipid in the gel phase and 17.5 molecules in the fluid phase, considerably smaller than inferred experimentally for 1

  6. Characterization of a light-controlled anion channel in the plasma membrane of mesophyll cells of pea

    NARCIS (Netherlands)

    Elzenga, J.T.M.; Volkenburgh Van, E

    In leaf mesophyll cells of pea (Pisum sativum) light induces a transient depolarization that is at least partly due to an increased plasma membrane conductance for anions. Several channel types were identified in the plasma membrane of protoplasts from mesophyll cells using the patch-clamp

  7. On the freezing behavior and diffusion of water in proximity to single-supported zwitterionic and anionic bilayer lipid membranes

    DEFF Research Database (Denmark)

    Miskowiec, A.; Buck, Z. N.; Brown, M. C.

    2014-01-01

    We compare the freezing/melting behavior of water hydrating single-supported bilayers of a zwitterionic lipid DMPC with that of an anionic lipid DMPG. For both membranes, the temperature dependence of the elastically scattered neutron intensity indicates distinct water types undergoing...... translational diffusion: bulk-like water probably located above the membrane and two types of confined water closer to the lipid head groups. The membranes differ in the greater width of the water freezing transition near the anionic DMPG bilayer compared to zwitterionic DMPC as well as in the abruptness...

  8. Development of anionic membranes produced by radiation-grafting for alkaline fuel cell applications

    International Nuclear Information System (INIS)

    Pereira, Clotilde Coppini

    2017-01-01

    Anion Exchange Membranes (AEMs) are a promising alternative to the development of more efficient electrolytes for alkaline fuel cells. In general, the AEMs are ionomeric membranes able to conduct hydroxide ions (OH - ) due to the quaternary ammonium groups, which confer high pH equivalent to the AEM. In order to develop alkaline membranes with high chemical and thermal stability, besides satisfactory ionic conductivity for alkaline fuel cells, membranes based on low density polyethylene (LDPE), ultrahigh weight molecular weight polyethylene (UHWHPE), poly(ethylene-co-tetrafluoroethylene) (PETFE) and poly(hexafluoropropylene-co-tetrafluoroethylene) (PFEP) previously irradiated by using 60 Co gamma and electron beam sources, have been synthesized by styrene-grafting, and functionalized with trimethylamine to introduced quaternary ammonium groups. The resulting membranes were characterized by electron paramagnetic resonance (EPR), Raman spectroscopy, thermogravimetry (TG) and electrochemical impedance spectroscopy (EIS). The determination of the grafting degree and water uptake were conducted by gravimetry and ion exchange capacity, by titration. The membranes synthesized with PELD and PEUHMW polymers pre-irradiated at 70 kGy and stored at low temperature (-70 deg C), up to 10 months, showed ionic conductivity results, in hydroxide form (OH - ), of 29 mS.cm -1 and 14 mS.cm -1 at 65 deg C, respectively. The PFEP polymers irradiated by the simultaneous process showed insufficient grating levels for the membrane synthesis, requiring more studies to improve the irradiation and grafting process. The styrene-grafted PETFE membranes, pre-irradiated at 70 kGy and stored at low temperature (-70 deg C), up to 10 months, showed ionic conductivity results, in hydroxide form (OH - ), of 90 mS.cm -1 to 165 mS.cm -1 , in the temperature range 30 to 60 deg C. Such results have demonstrated that LDPE, UHMWPE and PETFE based AEMs are promising electrolytes for alkaline fuel cell

  9. Recyclable cross-linked anion exchange membrane for alkaline fuel cell application

    Science.gov (United States)

    Hou, Jianqiu; Liu, Yazhi; Ge, Qianqian; Yang, Zhengjin; Wu, Liang; Xu, Tongwen

    2018-01-01

    Cross-linking can effectively solve the conductivity-swelling dilemma in anion exchange membranes (AEMs) but will generate solid wastes. To address this, we developed an AEM cross-linked via disulfide bonds, bearing quaternary ammonium groups, which can be easily recycled. The membrane (RC-QPPO) with IEC of 1.78 mmol g-1, when cross-linked, showed enhanced mechanical properties and good hydroxide conductivity (24.6 mS cm-1 at 30 °C). Even at higher IEC value (2.13 mmol g-1), it still has low water uptake, low swelling ratio and delivers a peak power density of 150 mW cm-2 at 65 °C. Exploiting the formation of disulfide bonds from -SH groups, the membrane can be readily cross-linked in alkaline condition and recycled by reversibly breaking disulfide bonds with dithiothreitol (DTT). The recycled membrane solution can be directly utilized to cast a brand-new AEM. By washing away the residual DTT with water and exposure to air, it can be cross-linked again and this process is repeatable. During the recycling and cross-linking processes, the membrane showed a slight IEC decrease of 5% due to functional group degradation. The strategy presented here is promising in enhancing AEM properties and reducing the impact of artificial polymers on the environment.

  10. Salt Concentration Differences Alter Membrane Resistance in Reverse Electrodialysis Stacks

    KAUST Repository

    Geise, Geoffrey M.

    2014-01-14

    Membrane ionic resistance is usually measured by immersing the membrane in a salt solution at a single, fixed concentration. While salt concentration is known to affect membrane resistance when the same concentration is used on both sides of the membrane, little is known about membrane resistance when the membrane is placed between solutions of different concentrations, such as in a reverse electrodialysis (RED) stack. Ionic resistance measurements obtained using Selemion CMV and AMV that separated sodium chloride and ammonium bicarbonate solutions of different concentrations were greater than those measured using only the high-concentration solution. Measured RED stack resistances showed good agreement with resistances calculated using an equivalent series resistance model, where the membranes accounted for 46% of the total stack resistance. The high area resistance of the membranes separating different salt concentration solutions has implications for modeling and optimizing membranes used in RED systems.

  11. Effects of anion size and concentration on electrolyte invasion into molecular-sized nanopores

    International Nuclear Information System (INIS)

    Liu Ling; Chen Xi; Kim, Taewan; Han Aijie; Qiao Yu

    2010-01-01

    When an electrolyte solution is pressurized into a molecular-sized nanopore, oppositely charged ions are strongly inclined to aggregate, which effectively reduces the ion solubility to zero. Inside the restrictive confinement, a unique quasi-periodic structure is formed where the paired ion couples are periodically separated by a number of water molecules. As the anion size or ion concentration varies, the geometrical characteristics of the confined ion structure would change considerably, leading to a significant variation in the transport pressure. Both experimental and simulation results indicate that, contradictory to the prediction of conventional theory, infiltration pressure decreases as the anions become larger.

  12. Effects of Cationic Pendant Groups on Ionic Conductivity for Anion Exchange Membranes: Structure Conductivity Relationships

    Science.gov (United States)

    Kim, Sojeong; Choi, Soo-Hyung; Lee, Won Bo

    Anion exchange membranes(AEMs) have been widely studied due to their various applications, especially for Fuel cells. Previous proton exchange membranes(PEMs), such as Nafions® have better conductivity than AEMs so far. However, technical limitations such as slow electrode kinetics, carbon monoxide (CO) poisoning of metal catalysts, high methanol crossover and high cost of Pt-based catalyst detered further usages. AEMs have advantages to supplement its drawbacks. AEMs are environmentally friendly and cost-efficient. Based on the well-defined block copolymer, self-assembled morphology is expected to have some relationship with its ionic conductivity. Recently AEMs based on various cations, including ammonium, phosphonium, guanidinium, imidazolium, metal cation, and benzimidazolium cations have been developed and extensively studied with the aim to prepare high- performance AEMs. But more fundamental approach, such as relationships between nanostructure and conductivity is needed. We use well-defined block copolymer Poly(styrene-block-isoprene) as a backbone which is synthesized by anionic polymerization. Then we graft various cationic functional groups and analysis the relation between morphology and conductivity. Theoretical and computational soft matter lab.

  13. Quest for anionic MOF membranes: Continuous sod -ZMOF membrane with Co2 adsorption-driven selectivity

    KAUST Repository

    Almaythalony, Bassem

    2015-02-11

    We report the fabrication of the first continuous zeolite-like metal-organic framework (ZMOF) thin-film membrane. A pure phase sod-ZMOF, sodalite topology, membrane was grown and supported on a porous alumina substrate using a solvothermal crystallization method. The absence of pinhole defects in the film was confirmed and supported by the occurrence of quantifiable time-lags, for all studied gases, during constant volume/variable pressure permeation tests. For both pure and mixed gas feeds, the sod-ZMOF-1 membrane exhibits favorable permeation selectivity toward carbon dioxide over relevant industrial gases such as H2, N2, and CH4, and it is mainly governed by favorable CO2 adsorption.

  14. Poly(vinylbenzylchloride) Based Anion-Exchange Blend Membranes (AEBMs): Influence of PEG Additive on Conductivity and Stability.

    Science.gov (United States)

    Kerres, Jochen A; Krieg, Henning M

    2017-06-16

    In view of the many possible applications such as fuel cells and electrolysers, recent interest in novel anion exchange membranes (AEMs) has increased significantly. However, their low conductivity and chemical stability limits their current suitability. In this study, the synthesis and characterization of several three- and four-component anion exchange blend membranes (AEBMs) is described, where the compositions have been systematically varied to study the influence of the AEBM's composition on the anion conductivities as well as chemical and thermal stabilities under strongly alkaline conditions. It was shown that the epoxide-functionalized poly(ethylene glycol)s that were introduced into the four-component AEBMs resulted in increased conductivity as well as a marked improvement in the stability of the AEBMs in an alkaline environment. In addition, the thermal stability of the novel AEBMs was excellent showing the suitability of these membranes for several electrochemical applications.

  15. Electrodialytic Transport Properties of Anion-Exchange Membranes Prepared from Poly(vinyl alcohol) and Poly(vinyl alcohol-co-methacryloyl aminopropyl trimethyl ammonium chloride).

    Science.gov (United States)

    Jikihara, Atsushi; Ohashi, Reina; Kakihana, Yuriko; Higa, Mitsuru; Kobayashi, Kenichi

    2013-01-02

    Random-type anion-exchange membranes (AEMs) have been prepared by blending poly(vinyl alcohol) (PVA) and the random copolymer-type polycation, poly(vinyl alcohol-co-methacryloyl aminopropyl trimethyl ammonium chloride) at various molar percentages of anion-exchange groups to vinyl alcohol groups, Cpc, and by cross-linking the PVA chains with glutaraldehyde (GA) solution at various GA concentrations, CGA. The characteristics of the random-type AEMs were compared with blend-type AEMs prepared in our previous study. At equal molar percentages of the anion exchange groups, the water content of the random-type AEMs was lower than that of the blend-type AEMs. The effective charge density of the random-type AEMs increased with increasing Cpc and reached a maximum value. Further, the maximum value of the effective charge density increased with increasing CGA. The maximum value of the effective charge density, 0.42 mol/dm3, was obtained for the random-type AEM with Cpc = 4.2 mol % and CGA = 0.15 vol %. A comparison of the random-type and blend-type AEMs with almost the same Cpc showed that the random-type AEMs had lower membrane resistance than the blend-type ones. The membrane resistance and dynamic transport number of the random-type AEM with Cpc = 6.0 mol % and CGA = 0.15 vol % were 4.8 Ω cm2 and 0.83, respectively.

  16. On the structure and dynamics of water associated with single-supported zwitterionic and anionic membranes

    DEFF Research Database (Denmark)

    Miskowiec, A.; Buck, Z. N.; Hansen, Flemming Yssing

    2017-01-01

    We have used high-resolution quasielastic neutron scattering (QENS) to investigate the dynamics of water molecules (time scale of motion similar to ∼10-11- 10-9 s) in proximity to single-supported bilayers of the zwitterionic lipid DMPC (1,2-dimyristoyl-sn-glycero-3-phosphorylcholine) and the ani......We have used high-resolution quasielastic neutron scattering (QENS) to investigate the dynamics of water molecules (time scale of motion similar to ∼10-11- 10-9 s) in proximity to single-supported bilayers of the zwitterionic lipid DMPC (1,2-dimyristoyl-sn-glycero-3-phosphorylcholine......) and the anionic lipid DMPG (1,2-dimyristoyl-sn-glycero-3-phosphoglycerol) in the temperature range 160-295 K. For both membranes, the temperature dependence of the intensity of neutrons scattered elastically and incoherently from these samples indicates a series of freezing/melting transitions...... the membrane and two types of confined water in closer proximity to the lipids. Specifically, we propose a water type termed "confined 2" located within and just above the lipid head groups of the membrane and confined 1 water that lies between the bulk-like and confined 2 water. Confined 1 water is only...

  17. Radiolytic preparation of ETFE and PFA based anion exchange membranes for alkaline fuel cell

    International Nuclear Information System (INIS)

    Ko, Beom-Seok; Sohn, Joon-Yong; Nho, Young-Chang; Shin, Junhwa

    2011-01-01

    In this study, a versatile monomer, vinylbenzyl chloride (VBC) was radiolytically grafted onto a partially fluorinated ETFE and perfluorinated polymer PFA films. The VBC grafted films were treated with trimethylamine to prepare the alkaline anion exchange membranes (AAEMs). No significant differences in the ion exchange capacities and water uptakes were observed between the ETFE and PFA based AAEMs with similar degree of grafting (DOG). However, the distribution patterns of the graft chains over the cross-section of the ETFE and PFA based AAEMs were found to be quite different; the even distribution was observed from the ETFE based AAEMs while the uneven distribution was observed from the PFA based AAEMs. It was also found that the PFA based AAEMs have the higher ionic conductivity and chemical stability, compared to the ETFE based AAEMs.

  18. Crosslinked anion exchange membranes prepared from poly(phenylene oxide) (PPO) for non-aqueous redox flow batteries

    Science.gov (United States)

    Li, Yun; Sniekers, Jeroen; Malaquias, João C.; Van Goethem, Cedric; Binnemans, Koen; Fransaer, Jan; Vankelecom, Ivo F. J.

    2018-02-01

    A stable and eco-friendly anion-exchange membrane (AEM) was prepared and applied in a non-aqueous all-copper redox flow battery (RFB). The AEM was prepared via a simple procedure, leading to a cross-linked structure containing quaternary ammonium groups without involvement of harmful trimethylamine. A network was thus constructed which ensured both ion transport and solvent resistance. The ion exchange capacity (IEC) of the membrane was tuned from 0.49 to 1.03 meq g-1 by varying the content of the 4, 4‧-bipyridine crosslinking agent. The membrane showed a good anion conductivity and retention of copper ions. As a proof of principle, a RFB single cell with this crosslinked membrane yielded a coulombic efficiency of 89%, a voltage efficiency of 61% and an energy efficiency of 54% at 7.5 mA cm-2.

  19. Effect of anionic surfactant concentration on the variable range hopping conduction in polypyrrole nanoparticles

    International Nuclear Information System (INIS)

    Rawal, Ishpal; Kaur, Amarjeet

    2014-01-01

    The mechanism of charge transport in polypyrrole (PPy) nanoparticles prepared with different concentrations (5 to 30 mM) of anionic surfactant (sodium dodecyl sulfate) is reported. Transmission electron microscopy technique confirms the formation of PPy nanoparticles of sizes ∼52 to 28 nm under surfactant directed approach. The room temperature electrical conductivity of the prepared nanoparticles found to increase from 3 to 22 S/cm with surfactant concentration. The temperature dependent activation energy rules out the possibility of band conduction mechanism in the prepared PPy nanoparticles and thus the synthesized nanoparticles are analyzed under variable range hopping (VRH) model for conduction mechanism. The PPy nanoparticles, reduced with liquid ammonia, hold 3D VRH conduction mechanism for the charge transport. However, in the doped samples, some deviation from 3D VRH conduction behavior at higher temperatures (>150 K) has been observed. This may be attributed to the presence of anionic surfactant in these samples. The doping of anionic surfactant causes rise in conducting islands, which may lead to the change in the shape/distribution of density of states governed by Gaussian or exponential type near Fermi level

  20. Effect of anionic surfactant concentration on the variable range hopping conduction in polypyrrole nanoparticles

    Science.gov (United States)

    Rawal, Ishpal; Kaur, Amarjeet

    2014-01-01

    The mechanism of charge transport in polypyrrole (PPy) nanoparticles prepared with different concentrations (5 to 30 mM) of anionic surfactant (sodium dodecyl sulfate) is reported. Transmission electron microscopy technique confirms the formation of PPy nanoparticles of sizes ˜52 to 28 nm under surfactant directed approach. The room temperature electrical conductivity of the prepared nanoparticles found to increase from 3 to 22 S/cm with surfactant concentration. The temperature dependent activation energy rules out the possibility of band conduction mechanism in the prepared PPy nanoparticles and thus the synthesized nanoparticles are analyzed under variable range hopping (VRH) model for conduction mechanism. The PPy nanoparticles, reduced with liquid ammonia, hold 3D VRH conduction mechanism for the charge transport. However, in the doped samples, some deviation from 3D VRH conduction behavior at higher temperatures (>150 K) has been observed. This may be attributed to the presence of anionic surfactant in these samples. The doping of anionic surfactant causes rise in conducting islands, which may lead to the change in the shape/distribution of density of states governed by Gaussian or exponential type near Fermi level.

  1. Determination of Trace Anions in Concentrated Hydrogen Peroxide by Direct Injection Ion Chromatography with Conductivity Detection after Pt-Catalyzed On-Line Decomposition

    International Nuclear Information System (INIS)

    Kim, Do Hee; Lee, Bo Kyung; Lee, Dong Soo

    1999-01-01

    A method has been developed for the determination of trace anion impurities in concentrated hydrogen peroxide. The method involves on-line decomposition of hydrogen peroxide, ion chromatographic separation and subsequent suppressed-type conductivity detection. H 2 O 2 is decomposed in Pt-catalyst filled Gore-Tex membrane tubing and the resulting aqueous solution containing analytes is introduced to the injection valve of an ion chromatograph for periodic determinations. The oxygen gas evolving within the membrane tubing escapes freely through the membrane wall causing no problem in ion chromatographic analysis. Decomposition efficiency is above 99.99% at a flow rate of 0.4mL/min for a 30% hydrogen peroxide concentration. Analytes are quantitatively retained. The analysis results for several brands of commercial hydrogen peroxides are reported

  2. Factors in electrode fabrication for performance enhancement of anion exchange membrane water electrolysis

    Science.gov (United States)

    Cho, Min Kyung; Park, Hee-Young; Choe, Seunghoe; Yoo, Sung Jong; Kim, Jin Young; Kim, Hyoung-Juhn; Henkensmeier, Dirk; Lee, So Young; Sung, Yung-Eun; Park, Hyun S.; Jang, Jong Hyun

    2017-04-01

    To improve the cell performance for alkaline anion exchange membrane water electrolysis (AEMWE), the effects of the amount of polytetrafluoroethylene (PTFE) non-ionomeric binder in the anode and the hot-pressing conditions during the fabrication of the membrane electrode assemblies (MEAs) on cell performances are studied. The electrochemical impedance data indicates that hot-pressing at 50 °C for 1 min during MEA construction can reduce the polarization resistance of AEMWE by ∼12%, and increase the initial water electrolysis current density at 1.8 V (from 195 to 243 mA cm-2). The electrochemical polarization and impedance results also suggest that the AEMWE performance is significantly affected by the content of PTFE binder in the anode electrode, and the optimal content is found to be 9 wt% between 5 and 20 wt%. The AEMWE device fabricated with the optimized parameters exhibits good water splitting performance (299 mA cm-2 at 1.8 V) without noticeable degradation in voltage cycling operations.

  3. Alkaline anion exchange membrane water electrolysis: Effects of electrolyte feed method and electrode binder content

    Science.gov (United States)

    Cho, Min Kyung; Park, Hee-Young; Lee, Hye Jin; Kim, Hyoung-Juhn; Lim, Ahyoun; Henkensmeier, Dirk; Yoo, Sung Jong; Kim, Jin Young; Lee, So Young; Park, Hyun S.; Jang, Jong Hyun

    2018-04-01

    Herein, we investigate the effects of catholyte feed method and anode binder content on the characteristics of anion exchange membrane water electrolysis (AEMWE) to construct a high-performance electrolyzer, revealing that the initial AEMWE performance is significantly improved by pre-feeding 0.5 M aqueous KOH to the cathode. The highest long-term activity during repeated voltage cycling is observed for AEMWE operation in the dry cathode mode, for which the best long-term performance among membrane electrode assemblies (MEAs) featuring polytetrafluoroethylene (PTFE) binder-impregnated (5-20 wt%) anodes is detected for a PTFE content of 20 wt%. MEAs with low PTFE content (5 and 9 wt%) demonstrate high initial performance, rapid performance decay, and significant catalyst loss from the electrode during long-term operation, whereas the MEA with 20 wt% PTFE allows stable water electrolysis for over 1600 voltage cycles. Optimization of cell operating conditions (i.e., operation in dry cathode mode at an optimum anode binder content following an initial solution feed) achieves an enhanced water splitting current density (1.07 A cm-2 at 1.8 V) and stable long-term AEMWE performance (0.01% current density reduction per voltage cycle).

  4. Steady state and transient simulation of anion exchange membrane fuel cells

    Science.gov (United States)

    Dekel, Dario R.; Rasin, Igal G.; Page, Miles; Brandon, Simon

    2018-01-01

    We present a new model for anion exchange membrane fuel cells. Validation against experimental polarization curve data is obtained for current densities ranging from zero to above 2 A cm-2. Experimental transient data is also successfully reproduced. The model is very flexible and can be used to explore the system's sensitivity to a wide range of material properties, cell design specifications, and operating parameters. We demonstrate the impact of gas inlet relative humidity (RH), operating current density, ionomer loading and ionomer ion exchange capacity (IEC) values on cell performance. In agreement with the literature, high air RH levels are shown to improve cell performance. At high current densities (>1 A cm-2) this effect is observed to be especially significant. Simulated hydration number distributions across the cell reveal the related critical dependence of cathode hydration on air RH and current density values. When exploring catalyst layer design, optimal intermediate ionomer loading values are demonstrated. The benefits of asymmetric (cathode versus anode) electrode design are revealed, showing enhanced performance using higher cathode IEC levels. Finally, electrochemical reaction profiles across the electrodes uncover inhomogeneous catalyst utilization. Specifically, at high current densities the cathodic reaction is confined to a narrow region near the membrane.

  5. The Position of Aβ22-40 and Aβ1-42 in Anionic Lipid Membranes Containing Cholesterol.

    Science.gov (United States)

    Barrett, Matthew A; Alsop, Richard J; Hauß, Thomas; Rheinstädter, Maikel C

    2015-11-30

    Amyloid-β peptides interact with cell membranes in the human brain and are associated with neurodegenerative diseases, such as Alzheimer's disease. An emerging explanation of the molecular mechanism, which results in neurodegeneration, places the cause of neurotoxicity of the amyloid- peptides on their potentially negative interaction with neuronal membranes. It is known that amyloid-β peptides interact with the membrane, modifying the membrane's structural and dynamic properties. We present a series of X-ray diffraction experiments on anionic model lipid membranes containing various amounts of cholesterol. These experiments provide experimental evidence for an interaction of both the full length amyloid-β1-42 peptide, and the peptide fragment amyloid-β22-40 with anionic bilayer containing cholesterol. The location of the amyloid-β peptides was determined from these experiments, with the full length peptide embedding into the membrane, and the peptide fragment occupying 2 positions-on the membrane surface and embedded into the membrane core.

  6. Determination of anionic concentrations in ground water samples using ion chromatography

    International Nuclear Information System (INIS)

    Prathibha, P.; Saradhi, I.V.; Pandit, G.G.; Puranik, V.D.

    2011-01-01

    Ion chromatography is a powerful separation technique for the quantitative measurement of anions in aqueous samples as well as in soil, sediment and air particulate samples leached in aqueous solutions. Ion chromatographic technique is developed by making use of suppressed ion conductivity detection (Small et.al.,1975) and it is a rapid multi ion analysis technique. The time, processing and effort required for the analysis of anions is much less compared to other techniques available such as ion selective electrode technique. In the present paper ground water samples collected around New BARC campus, Visakhapatnam are analyzed for anions using Ion chromatograph. The data generated will establish the current baseline status of the ionic contaminants in the study area. Groundwater samples are collected at 13 locations around BARC Vizag campus covering 30 km radius in September, 2009, April and July, 2010. The water samples include samples from hand pump and open wells in villages. The water samples are analyzed for fluoride, chloride, nitrate and sulphate using Metrohm make Ion chromatograph. The fluoride concentration in samples varied from 0.22 to 1.26 ppm, chloride from 18.7 to 810.9, nitrate from 1.34 to 378.5 ppm and sulphate from 13.29 to 250.69 ppm. No significant seasonal variations are observed in the samples collected from various locations except chloride at two locations. Ions Chromatograph is found to be a useful tool for simultaneous analysis of environmental samples with good accuracy where the concentrations of anions vary within an order of magnitude among them themselves. (author)

  7. Formation and stabilization of anionic metal complexes in concentrated aqueous quaternary ammonium salt solutions

    International Nuclear Information System (INIS)

    Aronson, F.L.; Hwang, L.L.Y.; Ronca, N.; Solomon, N.A.; Steigman, J.

    1985-01-01

    Anionic complexes of transition metals were stabilized in aqueous solutions containing high concentrations of various short-chain quaternary ammonium salts. Compounds with longer paraffin chains were effective in much less concentrated solution. Complex ions were detected spectrophotometrically. FeCl 4 - , which is usually formed in concentrated HCl, was the predominant Fe(III) complex in 30 m choline chloride containing only 0.12 M HCl. A yellow transitory Tc(VII) chloro-addition intermediate, formed in the reduction of TcO 4 - by concentrated HCl, was stabilized when the solution also contained 25 m choline chloride. Its spectrum, as well as the isolation of an already known Tc(VII) bipyridyl complex, is reported. Concentrated organic electrolytes also stabilized Tc(V) oxide halides against disproportionation and Tc(IV) hexahalides against hydrolysis. Halochromates of Cr(VI) were formed and stabilized in dilute acid containing quaternary ammonium salts. Their UV spectra showed the well-resolved vibronic fine structure associated with the symmetric chromium-to-oxygen charge-transfer band. It is known that these progressions are resolved in aprotic solvents, but not in aqueous acidic solution alone, and that the loss of fine structure in aqueous media is due to hydrogen bonding. The stabilization of anionic metal complexes and the resolution of vibronic structure in halochromates are probably consequences of water-structure-enforced ion paring. The present work suggests that the water molecules in immediate contact with the complex anions are more strongly hydrogen bonded to each other than to the complex. 21 references, 4 figures

  8. Study of the ion-channel behavior on glassy carbon electrode supported bilayer lipid membranes stimulated by perchlorate anion

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Zhiquan; Shi, Jun; Huang, Weimin, E-mail: huangwm@jlu.edu.cn

    2015-10-01

    In this paper, a kind of didodecyldimethylammonium bromide (DDAB) layer membranes was supported on a glassy carbon electrode (GCE). We studied the ion channel behavior of the supported bilayer lipid membrane by scanning electrochemical microscopy (SCEM) in tris(2,2′-bipyridine) ruthenium(II) solution. Perchlorate anion was used as a presence of stimulus and ruthenium(II) complex cations as the probing ions for the measurement of SECM, the lipid membrane channel was opened and exhibited the behavior of distinct SECM positive feedback curve. The channel was in a closed state in the absence of perchlorate anions while reflected the behavior of SECM negative feedback curve. The rates of electron transfer reaction in the lipid membranes surface were detected and it was dependant on the potential of SECM. - Highlights: • The rates of electron transfer reaction in the lipid membranes surface were detected. • Dynamic investigations of ion-channel behavior of supported bilayer lipid membranes by scanning electrochemical microscopy • A novel way to explore the interaction between molecules and supported bilayer lipid membranes.

  9. The role of polymer nanolayer architecture on the separation performance of anion-exchange membrane adsorbers: I. Protein separations.

    Science.gov (United States)

    Bhut, Bharat V; Weaver, Justin; Carter, Andrew R; Wickramasinghe, S Ranil; Husson, Scott M

    2011-11-01

    This contribution describes the preparation of strong anion-exchange membranes with higher protein binding capacities than the best commercial resins. Quaternary amine (Q-type) anion-exchange membranes were prepared by grafting polyelectrolyte nanolayers from the surfaces of macroporous membrane supports. A focus of this study was to better understand the role of polymer nanolayer architecture on protein binding. Membranes were prepared with different polymer chain graft densities using a newly developed surface-initiated polymerization protocol designed to provide uniform and variable chain spacing. Bovine serum albumin and immunoglobulin G were used to measure binding capacities of proteins with different size. Dynamic binding capacities of IgG were measured to evaluate the impact of polymer chain density on the accessibility of large size protein to binding sites within the polyelectrolyte nanolayer under flow conditions. The dynamic binding capacity of IgG increased nearly linearly with increasing polymer chain density, which suggests that the spacing between polymer chains is sufficient for IgG to access binding sites all along the grafted polymer chains. Furthermore, the high dynamic binding capacity of IgG (>130 mg/mL) was independent of linear flow velocity, which suggests that the mass transfer of IgG molecules to the binding sites occurs primarily via convection. Overall, this research provides clear evidence that the dynamic binding capacities of large biologics can be higher for well-designed macroporous membrane adsorbers than commercial membrane or resin ion-exchange products. Specifically, using controlled polymerization leads to anion-exchange membrane adsorbers with high binding capacities that are independent of flow rate, enabling high throughput. Results of this work should help to accelerate the broader implementation of membrane adsorbers in bioprocess purification steps. Copyright © 2011 Wiley Periodicals, Inc.

  10. Quaternized adamantane-containing poly(aryl ether ketone) anion exchange membranes for vanadium redox flow battery applications

    Science.gov (United States)

    Zhang, Bengui; Zhang, Shouhai; Weng, Zhihuan; Wang, Guosheng; Zhang, Enlei; Yu, Ping; Chen, Xiaomeng; Wang, Xinwei

    2016-09-01

    Quaternized adamantane-containing poly(aryl ether ketone) anion exchange membranes (QADMPEK) are prepared and investigated for vanadium redox flow batteries (VRFB) application. The bulky, rigid and highly hydrophobic adamantane segment incorporated into the backbone of membrane material makes QADMPEK membranes have low water uptake and swelling ratio, and the as-prepared membranes display significantly lower permeability of vanadium ions than that of Nafion117 membrane. As a consequence, the VRFB cell with QADMPEK-3 membrane shows higher coulombic efficiency (99.4%) and energy efficiency (84.0%) than those for Nafion117 membrane (95.2% and 80.5%, respectively) at the current density of 80 mA cm-2. Furthermore, at a much higher current density of 140 mA cm-2, QADMPEK membrane still exhibits better coulombic efficiency and energy efficiency than Nafion117 membrane (coulombic efficiency 99.2% vs 96.5% and energy efficiency 76.0% vs 74.0%). Moreover, QADMPEK membranes show high stability in in-situ VRFB cycle test and ex-situ oxidation stability test. These results indicate that QADMPEK membranes are good candidates for VRFB applications.

  11. Phospatidylserine or ganglioside--which of anionic lipids determines the effect of cationic dextran on lipid membrane?

    Science.gov (United States)

    Hąc-Wydro, Katarzyna; Wydro, Paweł; Cetnar, Andrzej; Włodarczyk, Grzegorz

    2015-02-01

    In this work the influence of cationic polymer, namely diethylaminoethyl DEAE-dextran on model lipid membranes was investigated. This polymer is of a wide application as a biomaterial and a drug carrier and its cytotoxicity toward various cancer cells was also confirmed. It was suggested that anticancer effect of cationic dextran is connected with the binding of the polymer to the negatively charged sialic acid residues overexpressed in cancer membrane. This fact encouraged us to perform the studies aimed at verifying whether the effect of cationic DEAE-dextran on membrane is determined only by the presence of the negatively charged lipid in the system or the kind of anionic lipid is also important. To reach this goal systematic investigations on the effect of dextran on various one-component lipid monolayers and multicomponent hepatoma cell model membranes differing in the level and the kind of anionic lipids (phosphatidylserine, sialic acid-containing ganglioside GM3 or their mixture) were done. As evidenced the results the effect of DEAE-dextran on the model system is determined by anionic lipid-polymer electrostatic interactions. However, the magnitude of the effect of cationic polymer is strongly dependent on the kind of anionic lipid in the model system. Namely, the packing and ordering of the mixtures containing ganglioside GM3 were more affected by DEAE-dextran than phosphatidylserine-containing monolayers. Although the experiments were done on model systems and therefore further studies are highly needed, the collected data may indicate that ganglioside may be important in the differentiation of the effect of cationic dextran on membranes. Copyright © 2014 Elsevier B.V. All rights reserved.

  12. Halloysite-derived nitrogen doped carbon electrocatalysts for anion exchange membrane fuel cells

    Science.gov (United States)

    Lu, Yaxiang; Wang, Lianqin; Preuß, Kathrin; Qiao, Mo; Titirici, Maria-Magdalena; Varcoe, John; Cai, Qiong

    2017-12-01

    Developing the low-cost, highly active carbonaceous materials for oxygen reduction reaction (ORR) catalysts has been a high-priority research direction for durable fuel cells. In this paper, two novel N-doped carbonaceous materials with flaky and rod-like morphology using the natural halloysite as template are obtained from urea nitrogen source as well as glucose (denoted as GU) and furfural (denoted as FU) carbon precursors, respectively, which can be directly applied as metal-free electrocatalysts for ORR in alkaline electrolyte. Importantly, compared with a benchmark Pt/C (20wt%) catalyst, the as-prepared carbon catalysts demonstrate higher retention in diffusion limiting current density (after 3000 cycles) and enhanced methanol tolerances with only 50-60mV negative shift in half-wave potentials. In addition, electrocatalytic activity, durability and methanol tolerant capability of the two N-doped carbon catalysts are systematically evaluated, and the underneath reasons of the outperformance of rod-like catalysts over the flaky are revealed. At last, the produced carbonaceous catalysts are also used as cathodes in the single cell H2/O2 anion exchange membrane fuel cell (AEMFC), in which the rod-like FU delivers a peak power density as high as 703 mW cm-2 (vs. 1106 mW cm-2 with a Pt/C benchmark cathode catalyst).

  13. A Cation-containing Polymer Anion Exchange Membrane based on Poly(norbornene)

    Science.gov (United States)

    Beyer, Frederick; Price, Samuel; Ren, Xiaoming; Savage, Alice

    Cation-containing polymers are being studied widely for use as anion exchange membranes (AEMs) in alkaline fuel cells (AFCs) because AEMs offer a number of potential benefits including allowing a solid state device and elimination of the carbonate poisoning problem. The successful AEM will combine high performance from several orthogonal properties, having robust mechanical strength even when wet, high hydroxide conductivity, and the high chemical stability required for long device lifetimes. In this study, we have synthesized a model cationic polymer that combines three of the key advantages of Nafion. The polymer backbone based on semicrystalline atactic poly(norbornene) offers good mechanical properties. A flexible, ether-based tether between the backbone and fixed cation charged species (quaternary ammonium) should provide the low-Tg, hydrophilic environment required to facilitate OH- transport. Finally, methyl groups have been added at the beta position relative to the quaternary ammonium cation to prevent Hoffman elimination, one mechanism by which AEMs are neutralized in a high pH environment. In this poster, we will present our findings on mechanical properties, morphology, charge transport, and chemical stability of this material.

  14. Simultaneous in-line concentration for spectrophotometric determination of cations and anions

    Directory of Open Access Journals (Sweden)

    Rocha Fábio R. P

    2004-01-01

    Full Text Available A flow system is proposed for simultaneous in-line concentration of cations and anions. A sliding-bar commutator was employed to insert an anion and a cation exchange column into a flowing sample stream for serial retention of the analytes. In the injector alternative position, different solutions flowed through the columns for parallel elution of the species in different analytical paths. Three-way solenoid valves allowed the intermittent reagent introduction in the sample zones. Signals were measured by employing two flow-through LED-based detectors. The simultaneous retention of the sample zones in coiled reactors can be also performed to increase the residence time and the analyte conversion rate. The analytical potentiality was demonstrated by the in-line concentration of ammonium and phosphate followed by spectrophotometric detection. For a 90 s loading time, the sampling rate was estimated as 40 determinations per hour, which is three-fold higher than the obtained without performing the tasks simultaneously. Enrichment factors of 8.0 and 18 were estimated for phosphate and ammonium, respectively, yielding detection limits of 1 mg L-1 PO4(3- and 1 mg L-1 NH4+ (99.7% confidence level. The reagent consumption was lower than 2 mg per determination. Results for freshwater samples agreed with the obtained by reference APHA procedures at the 95% confidence level.

  15. Facile synthesis of mesoporous silica sublayer with hierarchical pore structure on ceramic membrane using anionic polyelectrolyte.

    Science.gov (United States)

    Kang, Taewook; Oh, Seogil; Kim, Honggon; Yi, Jongheop

    2005-06-21

    A facile method for introducing mesoporous silica sublayer onto the surface of a ceramic membrane for use in liquid-phase separation is described. To reduce the electrostatic repulsion between the mesoporous silica sol and the ceramic membrane in highly acidic conditions (pH ceramic membrane, as confirmed by experimental titration data. Consistent with the titration results, the amount of mesoporous silica particles on the surface of the ceramic membrane was low, in the absence of PSS- treatment, whereas mesoporous silica sublayer with hierarchical pore structure was produced, when 1 wt % PSS- was used. The results show that mesoporous silica grows in the confined surface, eventually forming a multistacked surface architecture. The mesoporous silica sublayer contained uniform, ordered (P6 mm) mesopores of ca. 7.5 nm from mesoporous silica as well as macropores ( approximately mum) from interparticle voids, as evidenced by transmission electron microscopy and scanning electron microscopy analyses. The morphologies of the supported mesoporous silica could be manipulated, thus permitting the generation of uniform needlelike forms or uniform spheroid particles by varying the concentration of PSS-.

  16. Examination of Amine-Functionalised Anion-Exchange Membranes for Possible Use in the All-Vanadium Redox Flow Battery

    International Nuclear Information System (INIS)

    Mallinson, Sarah L.; Varcoe, John R.; Slade, Robert C.T.

    2014-01-01

    The applicability of amine-functionalised anion-exchange membranes (AEMs) for use in the all-vanadium redox flow battery has been studied. A selection of radiation-grafted aminated membranes functionalised with dimethylamine, trimethylamine or diazabicyclo(2,2,2)octane were extensively tested. The success of each grafting process was confirmed by Raman and infrared spectroscopies, titrimetry and ionic conductivity measurements. The amine-functionalised membranes were found to have poor thermo-oxidative stability and high vanadium cation permeabilities. The results highlight the importance of balancing ionic conductivity with vanadium cation permeability and indicate that amine-based functional groups may not be suitably stable for the membranes to remain true AEMs when in use in the all-vanadium redox flow battery

  17. The importance of OH − transport through anion exchange membrane in microbial electrolysis cells

    KAUST Repository

    Ye, Yaoli

    2018-01-11

    In two-chamber microbial electrolysis cells (MECs) with anion exchange membranes (AEMs), a phosphate buffer solution (PBS) is typically used to avoid increases in catholyte pH as Nernst equation calculations indicate that high pHs adversely impact electrochemical performance. However, ion transport between the chambers will also impact performance, which is a factor not included in those calculations. To separate the impacts of pH and ion transport on MEC performance, a high molecular weight polymer buffer (PoB), which was retained in the catholyte due to its low AEM transport and cationic charge, was compared to PBS in MECs and abiotic electrochemical half cells (EHCs). In MECs, catholyte pH control was less important than ion transport. MEC tests using the PoB catholyte, which had a higher buffer capacity and thus maintained a lower catholye pH (<8), resulted in a 50% lower hydrogen production rate (HPR) than that obtained using PBS (HPR = 0.7 m3-H2 m−3 d−1) where the catholyte rapidly increased to pH = 12. The main reason for the decreased performance using PoB was a lack of hydroxide ion transfer into the anolyte to balance pH. The anolyte pH in MECs rapidly decreased to 5.8 due to a lack of hydroxide ion transport, which inhibited current generation by the anode, whereas the pH was maintained at 6.8 using PBS. In abiotic tests in ECHs, where the cathode potential was set at −1.2 V, the HPR was 133% higher using PoB than PBS due to catholyte pH control, as the anolyte pH was not a factor in the performance. These results show that maintaining charge transfer to control anolyte pH is more important than obtaining a more neutral pH catholyte.

  18. Hydrogen concentration control utilizing a hydrogen permeable membrane

    International Nuclear Information System (INIS)

    Keating, S.J. Jr.

    1976-01-01

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

  19. Dependence of Shear and Concentration on Fouling in a Membrane Bioreactor with Rotating Membrane Discs

    DEFF Research Database (Denmark)

    Jørgensen, Mads Koustrup; Pedersen, Malene Thostrup; Christensen, Morten Lykkegaard

    2014-01-01

    Rotating ceramic membrane discs were fouled with lab-scale membrane bioreactors (MBR) sludge. Sludge filtrations were performed at varying rotation speeds and in different concentric rings of the membranes on different sludge concentrations. Data showed that the back transport expressed by limiting...... flux increased with rotation speed and distance from membrane center as an effect of shear. Further, the limiting flux decreased with increasing sludge concentration. A model was developed to link the sludge concentration and shear stress to the limiting flux. The model was able to simulate the effect...... of shear stress and sludge concentration on the limiting flux. The model was developed by calculating the shear rate at laminar flow regime at different rotation speeds and radii on the membrane. Furthermore, through the shear rate and shear stress, the non-Newtonian behavior of MBR sludge was addressed...

  20. Rearrangements under confinement lead to increased binding energy of Synaptotagmin-1 with anionic membranes in Mg2+ and Ca2.

    Science.gov (United States)

    Gruget, Clémence; Coleman, Jeff; Bello, Oscar; Krishnakumar, Shyam S; Perez, Eric; Rothman, James E; Pincet, Frederic; Donaldson, Stephen H

    2018-05-01

    Synaptotagmin-1 (Syt1) is the primary calcium sensor (Ca 2+ ) that mediates neurotransmitter release at the synapse. The tandem C2 domains (C2A and C2B) of Syt1 exhibit functionally critical, Ca 2+ -dependent interactions with the plasma membrane. With the surface forces apparatus, we directly measure the binding energy of membrane-anchored Syt1 to an anionic membrane and find that Syt1 binds with ~6 k B T in EGTA, ~10 k B T in Mg 2+ and ~18 k B T in Ca 2+ . Molecular rearrangements measured during confinement are more prevalent in Ca 2+ and Mg 2+ and suggest that Syt1 initially binds through C2B, then reorients the C2 domains into the preferred binding configuration. These results provide energetic and mechanistic details of the Syt1 Ca 2+ -activation process in synaptic transmission. © 2018 Federation of European Biochemical Societies.

  1. Highly stable pyridinium-functionalized cross-linked anion exchange membranes for all vanadium redox flow batteries

    Science.gov (United States)

    Zeng, L.; Zhao, T. S.; Wei, L.; Zeng, Y. K.; Zhang, Z. H.

    2016-11-01

    It has recently been demonstrated that the use of anion exchange membranes (AEMs) in vanadium redox flow batteries (VRFBs) can reduce the migration of vanadium ions through the membrane due to the Donnan exclusion effect among the positively charged functional groups and vanadium ions. However, AEMs are plagued by low chemical stability in harsh chemical environments. Here we propose and fabricate a pyridinium-functionalized cross-linked AEM for VRFBs. The pyridinium-functionalized bromomethylated poly (2,6-dimethyl-1,4-phenylene oxide) exhibits a superior chemical stability as a result of the strengthened internal cross-linking networks and the chemical inertness of the polymer backbone. Therefore, the membrane exhibits littler decay in a harsh environment for 20 days during the course of an ex situ immersion test. A cycling test also demonstrates that the VRFB assembled with the membrane enable to retain 80% of the initial discharge capacity over 537 cycles with a capacity decay rate of 0.037% cycle-1. Meanwhile, the membrane also shows a low vanadium permeability and a reasonably high conductivity in supporting electrolytes. Hence, all the measurements and performance tests reported in this work suggest that the membrane is a promising AEM for redox flow batteries to achieve excellent cycling stability and superior cell performance.

  2. Recovery of nitric acid from simulated acidic high level radioactive waste using pore-filled anion exchange membranes

    International Nuclear Information System (INIS)

    Chavan, Vivek; Agarwal, Chhavi; Pandey, A.K.; Goswami, A.

    2014-01-01

    Acidic waste is generated at different stages of nuclear fuel cycle. The waste contains minor amounts of actinides ( 241 Am, Pu, Np) along with large number of long-lived radionuclides such as 137 Cs, 90 Sr, 106 Ru etc. Before disposal or storage, the overall activity of the waste needs to be reduced. Along with this, the high amount of acid present in the waste needs to be removed. In this study, DD has been used to recover nitric acid from acidic solutions with compositions similar to radioactive waste using pore-filled anion exchange membranes

  3. Zeolite-filled silicone rubber membranes. Experimental determination of concentration profiles

    NARCIS (Netherlands)

    te Hennepe, H.J.C.; Boswerger, W.B.F.; Bargeman, D.; Bargeman, D.; Mulder, M.H.V.; Smolders, C.A.; Smolders, C.A.

    1994-01-01

    Permeant concentrations in silicalite-filled silicone rubber membranes during pervaporation of propanol/water mixtures were measured using multi-layered membranes. Experimentally determined concentration profiles show that the propanol concentration in the silicalite-filled membrane increases with

  4. Synthesis and characterisation of alkaline anionic-exchange membranes for direct alcohol fuel cells

    CSIR Research Space (South Africa)

    Nonjola, P

    2007-12-01

    Full Text Available , but the most important being proton exchange membrane fuel cell (PEMFC), which uses an acidic membrane like Nafion (sulfonated fluorocarbon polymers) as an electrolyte. The use of polymer electrolytes represents an interesting path to pursue...

  5. Facilitated Anion Transport Induces Hyperpolarization of the Cell Membrane That Triggers Differentiation and Cell Death in Cancer Stem Cells.

    Science.gov (United States)

    Soto-Cerrato, Vanessa; Manuel-Manresa, Pilar; Hernando, Elsa; Calabuig-Fariñas, Silvia; Martínez-Romero, Alicia; Fernández-Dueñas, Víctor; Sahlholm, Kristoffer; Knöpfel, Thomas; García-Valverde, María; Rodilla, Ananda M; Jantus-Lewintre, Eloisa; Farràs, Rosa; Ciruela, Francisco; Pérez-Tomás, Ricardo; Quesada, Roberto

    2015-12-23

    Facilitated anion transport potentially represents a powerful tool to modulate various cellular functions. However, research into the biological effects of small molecule anionophores is still at an early stage. Here we have used two potent anionophore molecules inspired in the structure of marine metabolites tambjamines to gain insight into the effect induced by these compounds at the cellular level. We show how active anionophores, capable of facilitating the transmembrane transport of chloride and bicarbonate in model phospholipid liposomes, induce acidification of the cytosol and hyperpolarization of plasma cell membranes. We demonstrate how this combined effect can be used against cancer stem cells (CSCs). Hyperpolarization of cell membrane induces cell differentiation and loss of stemness of CSCs leading to effective elimination of this cancer cell subpopulation.

  6. Densely quaternized poly(arylene ether)s with distinct phase separation for highly anion-conductive membranes

    Science.gov (United States)

    Hu, Yuanfang; Wang, Bingxi; Li, Xiao; Chen, Dongyang; Zhang, Weiying

    2018-05-01

    To develop high performance anion exchange membranes (AEMs), a novel bisphenol monomer bearing eight benzylmethyl groups at the outer edge of the molecule was synthesized, which after condensation polymerization with various amounts of 4,4‧-dihydroxydiphenylsulfone and 4,4‧-difluorobenzophenone yielded novel poly(arylene ether)s with densely located benzylmethyl groups. These benzylmethyl groups were then converted to quaternary ammonium groups by radical-initiated bromination and quaternization in tandem, leading to the emergence of densely quaternized poly(arylene ether sulfone)s (QA-PAEs) with controlled ion exchange capacities (IECs) ranging from 1.61 to 2.32 mmol g-1. Both small-angle X-ray scattering (SAXS) and transmission electron microscopy (TEM) studies revealed distinct phase separation in the QA-PAEs. The QA-PAE-40 with an IEC of 2.32 mmol g-1 exhibited a Br- conductivity of 9.2 mS cm-1 and a SO42- conductivity of 14.0 mS cm-1 at room temperature, much higher than those of a control membrane with a similar IEC but without obvious phase separation. Therefore, phase separation of AEMs was validated to be advantageous for the efficient conducting of anions. The experimental results also showed that the QA-PAEs were promising AEM materials, especially for non-alkaline applications.

  7. Anion exchange membranes based on terminally crosslinked methyl morpholinium-functionalized poly(arylene ether sulfone)s

    Science.gov (United States)

    Kwon, Sohyun; Rao, Anil H. N.; Kim, Tae-Hyun

    2018-01-01

    Azide-assisted terminal crosslinking of methyl morpholinium-functionalized poly(arylene ether sulfone) block copolymers yields products (xMM-PESs) suitable for use as anion exchange membranes. By combining the advantages of bulky morpholinium conductors and our unique polymer network crosslinked only at the termini of the polymer chains, we can produce AEMs that after the crosslinking show minimal loss in conductivity, yet with dramatically reduced water uptake. Terminal crosslinking also significantly increases the thermal, mechanical and chemical stability levels of the membranes. A high ion conductivity of 73.4 mS cm-1 and low water uptake of 26.1% at 80 °C are obtained for the crosslinked membrane with higher amount of hydrophilic composition, denoted as xMM-PES-1.5-1. In addition, the conductivity of the crosslinked xMM-PES-1.5-1 membrane exceeds that of its non-crosslinked counterpart (denoted as MM-PES-1.5-1) above 60 °C at 95% relative humidity because of its enhanced water retention capacity caused by the terminally-crosslinked structure.

  8. Characterization of anionic-exchange membranes for direct alcohol alkaline fuel cells

    CSIR Research Space (South Africa)

    Abuin, GC

    2009-06-01

    Full Text Available and Young modulus were evaluated and compared to other membrane materials commonly employed in PEM fuel cells. A quartz crystal microbalance (QMC) was used to measure the water uptake of thin membranes of this material casted over the quartz crystals...

  9. Anion exchange membrane based on alkali doped poly(2,5-benzimidazole) for fuel cell

    CSIR Research Space (South Africa)

    Luo, H

    2012-02-01

    Full Text Available The properties of alkali doped poly(2,5-benzimidazole) membrane with different alkali doping level for fuel cell application is reported in this work. The alkali doping level played an important role for the ion conductivity of the membrane. The ion...

  10. Anion- or Cation-Exchange Membranes for NaBH4/H2O2 Fuel Cells?

    Directory of Open Access Journals (Sweden)

    César A. C. Sequeira

    2012-07-01

    Full Text Available Direct borohydride fuel cells (DBFC, which operate on sodium borohydride (NaBH4 as the fuel, and hydrogen peroxide (H2O2 as the oxidant, are receiving increasing attention. This is due to their promising use as power sources for space and underwater applications, where air is not available and gas storage poses obvious problems. One key factor to improve the performance of DBFCs concerns the type of separator used. Both anion- and cation-exchange membranes may be considered as potential separators for DBFC. In the present paper, the effect of the membrane type on the performance of laboratory NaBH4/H2O2 fuel cells using Pt electrodes is studied at room temperature. Two commercial ion-exchange membranes from Membranes International Inc., an anion-exchange membrane (AMI-7001S and a cation-exchange membrane (CMI-7000S, are tested as ionic separators for the DBFC. The membranes are compared directly by the observation and analysis of the corresponding DBFC’s performance. Cell polarization, power density, stability, and durability tests are used in the membranes’ evaluation. Energy densities and specific capacities are estimated. Most tests conducted, clearly indicate a superior performance of the cation-exchange membranes over the anion-exchange membrane. The two membranes are also compared with several other previously tested commercial membranes. For long term cell operation, these membranes seem to outperform the stability of the benchmark Nafion membranes but further studies are still required to improve their instantaneous power load.

  11. Atomistic simulations of anionic Au-144(SR)(60) nanoparticles interacting with asymmetric model lipid membranes

    DEFF Research Database (Denmark)

    Heikkila, E.; Martinez-Seara, H.; Gurtovenko, A. A.

    2014-01-01

    whose lipid composition and transmembrane distribution are to a large extent consistent with real plasma membranes of eukaryotic cells. To this end, we use a model system which comprises two cellular compartments, extracellular and cytosolic, divided by two asymmetric lipid bilayers. The simulations...... clearly show that AuNP- attaches to the extracellular membrane surface within a few tens of nanoseconds, while it avoids contact with the membrane on the cytosolic side. This behavior stems from several factors. In essence, when the nanoparticle interacts with lipids in the extracellular compartment...

  12. Preparation of silica nanocomposite anion-exchange membranes with low vanadium-ion crossover for vanadium redox flow batteries

    International Nuclear Information System (INIS)

    Leung, P.K.; Xu, Q.; Zhao, T.S.; Zeng, L.; Zhang, C.

    2013-01-01

    Highlights: • The permeability of vanadium ions through the silica nanocomposite AEM (SNAEM) is ten times lower than that for Nafion 115. • The rates of self-discharge and capacity fading of the VRFB are substantially reduced with the use of the SNAEM. • The Coulombic and energy efficiencies are as high as 92% and 73%, respectively, at 40 mA cm −2 . -- Abstract: Crossover of vanadium ions through the membranes of all-vanadium redox flow batteries (VRFB) is an issue that limits the performance of this type of flow battery. This paper reports on the preparation of a sol–gel derived silica nanocomposite anion exchange membrane (AEM) for VRFBs. The EDS and FT-IR characterizations confirm the presence and the uniformity of the silica nanoparticles formed in the membrane via an in situ sol–gel process. The properties of the obtained membrane, including the ion-exchange capacity, the area resistance, and the water uptake, are evaluated and compared to the pristine AEM and the Nafion cation exchange membrane (CEM). The experimental results show that the permeability of the vanadium ions through the silica nanocomposite AEM is about 20% lower than that of the pristine AEM, and one order of magnitude lower than that of the Nafion CEM. As a result, the rates of self-discharge and the capacity fading of the VRFB are substantially reduced. The Coulombic and energy efficiencies at a current density of 40 mA cm −2 are, respectively, as high as 92% and 73%

  13. Anionic-exchange membrane development for application in alcohol alkaline fuel cells

    CSIR Research Space (South Africa)

    Nonjola, S

    2010-09-01

    Full Text Available . In this work, a quaternary ammonium polymer was synthesized by chloromethylation of a commercial polysulfone followed by amination process. Quaternized polysulfone membrane properties such us water and water-methanol uptake, electrical conductivity and Young...

  14. Helicobacter pylori VacA toxin/subunit p34: targeting of an anion channel to the inner mitochondrial membrane.

    Directory of Open Access Journals (Sweden)

    Grazyna Domańska

    2010-04-01

    Full Text Available The vacuolating toxin VacA, released by Helicobacter pylori, is an important virulence factor in the pathogenesis of gastritis and gastroduodenal ulcers. VacA contains two subunits: The p58 subunit mediates entry into target cells, and the p34 subunit mediates targeting to mitochondria and is essential for toxicity. In this study we found that targeting to mitochondria is dependent on a unique signal sequence of 32 uncharged amino acid residues at the p34 N-terminus. Mitochondrial import of p34 is mediated by the import receptor Tom20 and the import channel of the outer membrane TOM complex, leading to insertion of p34 into the mitochondrial inner membrane. p34 assembles in homo-hexamers of extraordinary high stability. CD spectra of the purified protein indicate a content of >40% beta-strands, similar to pore-forming beta-barrel proteins. p34 forms an anion channel with a conductivity of about 12 pS in 1.5 M KCl buffer. Oligomerization and channel formation are independent both of the 32 uncharged N-terminal residues and of the p58 subunit of the toxin. The conductivity is efficiently blocked by 5-nitro-2-(3-phenylpropylaminobenzoic acid (NPPB, a reagent known to inhibit VacA-mediated apoptosis. We conclude that p34 essentially acts as a small pore-forming toxin, targeted to the mitochondrial inner membrane by a special hydrophobic N-terminal signal.

  15. The Effect of Concentration Factor on Membrane Fouling

    Directory of Open Access Journals (Sweden)

    Appana Lok

    2017-09-01

    Full Text Available Bench-scale systems are often used to evaluate pretreatment methods and operational conditions that can be applied in full-scale ultrafiltration (UF systems. However, the membrane packing density is substantially different in bench and full-scale systems. Differences in concentration factor (CF at the solution–membrane interface as a result of packing density may impact the mass transfer and fouling rate and the applicability of bench-scale systems. The present study compared membrane resistance when considering raw water (CF = 1 and reject water (also commonly referred to as concentrate water (CF > 1 as feed in UF systems operated in deposition (dead-end mode. A positive relationship was observed between the concentration of the organic matter in the solution being filtered and resistance. Bench-scale trials conducted with CF = 1 water were more representative of full-scale operation than trials conducted with elevated CFs when considering membrane resistance and permeate quality. As such, the results of this study indicate that the use of the same feed water as used at full-scale (CF = 1 is appropriate to evaluate fouling in UF systems operated in deposition mode.

  16. The purified ATPase from chromaffin granule membranes is an anion-dependent proton pump.

    Science.gov (United States)

    Moriyama, Y; Nelson, N

    1987-07-05

    The proton-ATPase of chromaffin granules was purified so as to maintain its proton-pumping activity when reconstituted into phospholipid vesicles. The purification procedure involved solubilization with polyoxyethylene 9 lauryl ether, hydroxylapatite column, precipitation by ammonium sulfate, and glycerol gradient centrifugation. The protease inhibitor mixture used in previous studies inhibited the proton-pumping activity of the enzyme; therefore, the protein was stabilized by pepstatin A and leupeptin. The enzyme was purified at least 50-fold with respect to both ATPase and proton-pumping activity. The ATP-dependent proton uptake activity of the reconstituted enzyme was absolutely dependent on the presence of Cl- or Br- outside the vesicles, whereas sulfate, acetate, formate, nitrate, and thiocyanate were inhibitory. Sulfate inhibition seems to be due to competition with Cl- on the anion-binding site outside the vesicles, whereas nitrate and thiocyanate inhibited only from the internal side. As with the inhibition by N-ethylmaleimide, the proton-pumping activity was much more sensitive to nitrate than the ATPase activity. About 20 mM nitrate were sufficient for 90% inhibition of the proton-pumping activity while 100 mM inhibited only 50% of the ATPase activity both in situ and in the reconstituted enzyme. The possible regulatory effect of anions on the ATP-dependent proton uptake in secretory granules is discussed.

  17. Cytochrome b5 reductase is the component from neuronal synaptic plasma membrane vesicles that generates superoxide anion upon stimulation by cytochrome c

    Directory of Open Access Journals (Sweden)

    Alejandro K. Samhan-Arias

    2018-05-01

    Full Text Available In this work, we measured the effect of cytochrome c on the NADH-dependent superoxide anion production by synaptic plasma membrane vesicles from rat brain. In these membranes, the cytochrome c stimulated NADH-dependent superoxide anion production was inhibited by antibodies against cytochrome b5 reductase linking the production to this enzyme. Measurement of the superoxide anion radical generated by purified recombinant soluble and membrane cytochrome b5 reductase corroborates the production of the radical by different enzyme isoforms. In the presence of cytochrome c, a burst of superoxide anion as well as the reduction of cytochrome c by cytochrome b5 reductase was measured. Complex formation between both proteins suggests that cytochrome b5 reductase is one of the major partners of cytochrome c upon its release from mitochondria to the cytosol during apoptosis. Superoxide anion production and cytochrome c reduction are the consequences of the stimulated NADH consumption by cytochrome b5 reductase upon complex formation with cytochrome c and suggest a major role of this enzyme as an anti-apoptotic protein during cell death.

  18. Anion-Exchange Membrane Fuel Cells with Improved CO2 Tolerance: Impact of Chemically Induced Bicarbonate Ion Consumption.

    Science.gov (United States)

    Katayama, Yu; Yamauchi, Kosuke; Hayashi, Kohei; Okanishi, Takeou; Muroyama, Hiroki; Matsui, Toshiaki; Kikkawa, Yuuki; Negishi, Takayuki; Watanabe, Shin; Isomura, Takenori; Eguchi, Koichi

    2017-08-30

    Over the last few decades, because of the significant development of anion exchange membranes, increasing efforts have been devoted the realization of anion exchange membrane fuel cells (AEMFCs) that operate with the supply of hydrogen generated on-site. In this paper, ammonia was selected as a hydrogen source, following which the effect of conceivable impurities, unreacted NH 3 and atmospheric CO 2 , on the performance of AEMFCs was established. As expected, we show that these impurities worsen the performance of AEMFCs significantly. Furthermore, with the help of in situ attenuated total reflection infrared (ATR-IR) spectroscopy, it was revealed that the degradation of the cell performance was primarily due to the inhibition of the hydrogen oxidation reaction (HOR). This is attributed to the active site occupation by CO-related adspecies derived from (bi)carbonate adspecies. Interestingly, this degradation in the HOR activity is suppressed in the presence of both NH 3 and HCO 3 - because of the bicarbonate ion consumption reaction induced by the existence of NH 3 . Further analysis using in situ ATR-IR and electrochemical methods revealed that the poisonous CO-related adspecies were completely removed under NH 3 -HCO 3 - conditions, accompanied by the improvement in HOR activity. Finally, a fuel cell test was conducted by using the practical AEMFC with the supply of NH 3 -contained H 2 gas to the anode and ambient air to the cathode. The result confirmed the validity of this positive effect of NH 3 -HCO 3 - coexistence on CO 2 -tolerence of AEMFCs. The cell performance achieved nearly 95% of that without any impurity in the fuels. These results clearly show the impact of the chemically induced bicarbonate ion consumption reaction on the realization of highly CO 2 -tolerent AEMFCs.

  19. Concentration dependence of halide fluxes and selectivity of the anion pathway in toad skin

    DEFF Research Database (Denmark)

    Harck, A F; Larsen, Erik Hviid

    1986-01-01

    The isolated toad (Bufo bufo) skin was mounted under voltage-clamp conditions in a chamber shown to cause no significant edge damage. The serosal side of the skin was bathed with NaCl-Ringer's, and the passive voltage-sensitive anion conductance studied in its fully voltage activated state, V = -...

  20. REVERSE OSMOSIS CONCENTRATION OF ORANGE JUICE USING SPIRAL WOUND MEMBRANES

    Directory of Open Access Journals (Sweden)

    W. A. de ARAUJO

    2009-03-01

    Full Text Available

    Flavor and odor components of foods are often lost during processing which leads to a poorer quality final product compared with the fresh ingredients. The orange juice industry concentrates juice (45-66ºBrix in TASTE (Thermally Accelerated Short Time Evaporator to remove excess water, and thus reduce storage and transportation costs, but also to improve product stability. Evaporation results in a loss of fresh juice flavors, color degradation and “cooked” taste due to the thermal effects. Methods using less heat for thermal damage reduction must be investigated to establish parameters for future commercial processes. The promising alternative is Reverse Osmosis (RO, but it cannot achieve concentrations greater than 30ºBrix. RO has advantages over traditional evaporation techniques in removing water. Because less heat is used, thermal damage to products is generally eliminated. In this project tests were performed using unpasteurised Single Strength Orange Juice (SSOJ, spiral wound membranes (Polyamide, and a DESAL pilot system model 4040. The aim was to evaluate spiral wound membranes on the basis of flux as a function of time. Retentate concentrations were 15-20ºBrix, and GC-FID analyses were used in order to understand aroma losses. KEYWORDS: Orange; juice; membrane; concentration; osmosis; reverse.

  1. Kinetics of Ca2+- and ATP-dependent, voltage-controlled anion conductance in the plasma membrane of mesophyll cells of Pisum sativum

    NARCIS (Netherlands)

    Elzenga, J.T.M.; van Volkenburgh, E.

    Whole-cell patch-clamp techniques were used to measure anion currents through the plasma membrane of protoplasts of mesophyll cells of expanding pea (Pisum sativum L.) leaves. Voltage-induced changes of the currents could be modelled with single exponential activation and deactivation kinetics. The

  2. Chemical modification of polysulfone: composite anionic exchange membrane with TiO2 nano-particles

    CSIR Research Space (South Africa)

    Nonjola, PT

    2013-04-01

    Full Text Available -chemical properties studied by means of SEM and XRD techniques suggested the uniform and homogeneous distribution of TiO2 at 2.5wt. % loading, and negligible agglomeration at 10wt % loading, also indicated enhancement of crystalline character of these membranes...

  3. The influence of plutonium concentration and solution flow rate on the effective capacity of macroporous anion exchange resin

    International Nuclear Information System (INIS)

    Marsh, S.F.; Gallegos, T.D.

    1987-07-01

    The principal aqueous process used to recover and purify plutonium at the Los Alamos Plutonium Facility is anion exchange in nitric acid. Previous studies with gel-type anion exchange resin have shown an inverse relationship between plutonium concentration in the feed solution and the optimum flow rate for this process. Because gel-type resin has been replaced with macroporous resin at Los Alamos, the relationship between plutonium concentration and solution flow rate was reexamined with the selected Lewatit MP-500-FK resin using solutions of plutonium in nitric acid and in nitric acid with high levels of added nitrate salts. Our results with this resin differ significantly from previous data obtained with gel-type resin. Flow-rate variation from 10 to 80 liters per hour had essentially no effect on the measured quantities of plutonium sorbed by the macroporous resin. However, the effect of plutonium concentration in the feed solutions was pronounced, as feed solutions that contained the highest concentrations of plutonium also produced the highest resin loadings. The most notable effect of high concentrations of dissolved nitrate salts in these solutions was an increased resin capacity for plutonium at low flow rates. 16 refs., 7 figs., 2 tabs

  4. Highly Stable Anion Exchange Membranes for High-Voltage Redox-Flow Batteries

    Energy Technology Data Exchange (ETDEWEB)

    Yan, Yushan [Univ. of Delaware, Newark, DE (United States)

    2018-02-26

    In this work, multiple polymer backbones were screened for oxidation resistance and multiple chemistries were explored for tethering tris(2,4,6-trimethylphenyl)phosphonium (9MeTTP+) to the selected polymer backbones. A new tethering strategy through brominated 9MeTTP+ cation was developed and used to obtain the desired 9MeTTP+-functionalized polysulfone (PSf) and hexafluoro polybenzimidazole (F6PBI) polymer. The crosslinked 9MeTTP+-functionalized hexafluoro polybenzimidazole (9MeTTP-F6PBI) polymer demonstrated excellent oxidation stability that met the go-no-go milestone of the first year. However, large-scale bromination inevitably involved multi-bromination products, which led to polymer crosslinking in the next tethering. A new synthesis strategy with diiodobutane as linker was developed to overcome the crosslinking problem. The prepared 9MeTTP+-F6PBI membrane without crosslinking showed only 3.58% water uptake and less than 1 mS/cm OH- conductivity in water at 20°C, possibly due to the hydrophobic 9MeTTP+ cation. In order to improve the conductivity, hydrophilic tris(2,4,6-trimethoxylphenyl)phosphonium (9MeOTTP+) cation was tethered to an F6PBI backbone, and a 9MeOTTP+-F6PBI PTFE reinforced membrane was prepared with 17.4% water uptake to increase the mechanical strength and durability in cerium (IV) solution. A 9MeOTTP+-F6PBI PTFE reinforced membrane had less than 20% conductivity loss during an accelerated stability test in 0.5 M cerium (IV) and 1.3 M HClO4 at 55°C for 100 hours. Moreover, a 9MeOTTP+-F6PBI PTFE reinforced membrane had more than double the lifetime of commercial FAS-30 and FAB-PK-130 AEMs during an accelerated stability test in 0.5 M cerium (IV) and 1.3 M HClO4 at 55°C. Low area specific resistance (ASR) of a 9MeOTTP+-F6PBI PTFE reinforced

  5. Liquid anion exchangers (LAE) as novel receptors for plutonium pertraction across polymer immobilized liquid membranes

    International Nuclear Information System (INIS)

    Sonawane, J.V.; Anil Kumar; Sawant, S.R.; Singh, R.K.; Bajpai, D.D.; Shukla, J.P.

    1999-03-01

    The diffusion-limited and amine-facilitated Pu 4+ cation permeation in nitric acid media across a polymer immobilized liquid membrane (PILM) has been investigated to quantify the membrane carrier type effects on its transport. Primene JM-T (JMT) as primary, Amberlite LA-2 (Amb LA-2) as secondary, trilaurylamine (TLA] and triiso-octyl amine (TIOA) as tertiary and Adogen-464 (Ado-464) and Aliquat-336 (Ali-336) as quaternary amines as typical examples of nitrogen containing basic extractants are tested as the carriers. After suitable dilutions, the receptors are immobilized on a microporous polymeric support which are held within the pores by capillary forces. Both the composition of the organic membrane solvents and type of amine carriers exert a marked effect on plutonium permeation. Recovery of Pu steadily increases from primary to quaternary amines; its permeability across PILM roughly follows the order quaternary > tertiary > secondary > primary, similar to that generally observed in liquid-liquid distribution experiments. More than 95% pertraction of Pu(IV) is easily accomplished using tertiary or quaternary amine as ionophores across PILM in single run employing a feed solution containing about 5 mg dm -3 Pu in 4 M nitric acid solution while the receiving phase is 0.1M NH 2 OH.HCl prepared in 0.3M HNO 3 . On the other hand, plutonium permeation at 4M HNO 3 under similar experimental conditions using other types of amines as carriers namely primary amine, Pri JM-T afforded only 19% and 49% by Amb LA-2 in 6-7h runs. Results of the detailed study to evaluate the effect of other contaminants on Pu transport are also discussed. (author)

  6. Heterogeneous anion conducting membranes based on linear and crosslinked KOH doped polybenzimidazole for alkaline water electrolysis

    DEFF Research Database (Denmark)

    Aili, David; Hansen, Martin Kalmar; Renzaho, Richard Fulgence

    2013-01-01

    Polybenzimidazole is a highly hygroscopic polymer that can be doped with aqueous KOH to give a material with high ion conductivity in the 10−2Scm−1 range, which in combination with its low gas permeability makes it an interesting electrolyte material for alkaline water electrolysis. In this study...... on their linear counterpart. The technical feasibility of the membranes was evaluated by the preliminary water electrolysis tests showing performance comparable to that of commercially available cell separators with great potential of further improvement....

  7. Comparative study on TSPM levels, anions and trace metal concentrations at BARC during the years 2000-2002

    International Nuclear Information System (INIS)

    Saradhi, I.V.; Prathibha, P.; Kothai, G.; Mahadevan, T.N.; Venkat Raj, V.; Kumar, Shaji C.

    2003-01-01

    Both total and respirable suspended particulate matter in the ambient air of Mumbai have been identified as the single largest pollutant associated with the health impacts in the community. This study deals with the extensive monitoring work carried out at BARC, Trombay during the period 2000-2002. The paper also deals with the comparative status of the TSPM levels and select trace metal and anion concentrations. While Pb levels have stabilized over the years following the introduction of unleaded gasoline, sulphate as a major contributor in the fine fraction of SPM assumes importance. The possible source profiles are presented and discussed. (author)

  8. Influence of concentration and hydrodynamic factors in sorption of iodine by anion-exchangers of the mass-transfer rate

    International Nuclear Information System (INIS)

    Sokolov, V.V.; Smirnov, N.N.

    1982-01-01

    An investigation of the joint influence of hydrodynamic and concentration factors in sorption of iodine by AV-17-8 and anion exchange resins on the mass-transfer coefficient is the subject of this report. The method of central composite rotatable experimental design was used for quantitative assessment and derivation of the appropriate equations. The investigation yielded the necessary regression equations satisfactorily describing the influence of all the factors in the mass-transfer coefficient. the optimal mass-transfer conditions were determined. On the basis of the values obtained, recommendations are made on the optimal hydrodynamic conditions of operation of equipment with pneumatic circulation of the ion-exchanger

  9. Evaluation of anionic surfactant concentrations in US effluents and probabilistic determination of their combined ecological risk in mixing zones.

    Science.gov (United States)

    McDonough, Kathleen; Casteel, Kenneth; Itrich, Nina; Menzies, Jennifer; Belanger, Scott; Wehmeyer, Kenneth; Federle, Thomas

    2016-12-01

    Alcohol sulfates (AS), alcohol ethoxysulfates (AES), linear alkyl benzenesulfonates (LAS) and methyl ester sulfonates (MES) are anionic surfactants that are widely used in household detergents and consumer products resulting in over 1 million tons being disposed of down the drain annually in the US. A monitoring campaign was conducted which collected grab effluent samples from 44 wastewater treatment plants (WWTPs) across the US to generate statistical distributions of effluent concentrations for anionic surfactants. The mean concentrations for AS, AES, LAS and MES were 5.03±4.5, 1.95±0.7, 15.3±19, and 0.35±0.13μg/L respectively. Since each of these surfactants consist of multiple homologues that differ in their toxicity, the concentration of each homologue measured in an effluent sample was converted into a toxic unit (TU) by normalizing to the predicted no effect concentration (PNEC) derived from high tier effects data (mesocosm studies). The statistical distributions of the combined TUs in the effluents were used in combination with distributions of dilution factors for WWTP mixing zones to conduct a US-wide probabilistic risk assessment for the aquatic environment for each of the surfactants. The 90th percentile level of TUs for AS, AES, LAS and MES in mixing zones were 1.89×10 -2 , 2.73×10 -3 , 2.72×10 -2 , and 3.65×10 -5 under 7Q10 (lowest river flow occurring over a 7day period every 10years) low flow conditions. Because these surfactants have the same toxicological mode of action, the TUs were summed and the aquatic safety for anionic surfactants as a whole was assessed. At the 90th percentile level under the conservative 7Q10 low flow conditions the forecasted TUs were 4.21×10 -2 which indicates that there is a significant margin of safety for the class of anionic surfactants in US aquatic environments. Copyright © 2016 Elsevier B.V. All rights reserved.

  10. Concentration of Selected Anions in Bottled Water in the United Arab Emirates

    Directory of Open Access Journals (Sweden)

    Mohamed Yehia Z. Abouleish

    2012-05-01

    Full Text Available Several studies have shown concern over nitrate and nitrite contamination of prepared infant formula used by infants less than six months old, as it may lead to methemoglobinemia and death. One possible source of contamination is through the use of improperly treated drinking water. Contamination of water could result from fertilizers and manure runoff, not fully treated and released human and industrial waste, or from disinfection processes. In the United Arab Emirates (UAE, bottled water is the major source of drinking water and may be used for the preparation of infant formula. Therefore, in this study, several bottled water brands that are sold on the UAE market, and could be used for preparation of infant formula, were tested for nitrate and nitrite and other anions to show their compatibility with the permissible levels of the United States Environmental Protection Agency (U.S. EPA, United States Food and Drug Administration/Code of Federal Regulations (U.S. FDA/CFR, and other international organizations. All the bottled water samples demonstrated nitrate, nitrite, and other anions levels below the permissible levels accepted by U.S. EPA, U.S. FDA/CFR, and other international organizations, except for one sample that showed nitrite levels exceeding the European Commission and Drinking Water Directive (EC/DWD permissible levels. Such study sheds light on the quality of bottled water sold not only in the UAE and the region, but also in other countries, such as France, since some of them are imported. In addition, the results shed light on the effectiveness of the treatment processes and possible sources of infant formula contamination that can affect the health of infants.

  11. PdRu/C catalysts for ethanol oxidation in anion-exchange membrane direct ethanol fuel cells

    Science.gov (United States)

    Ma, Liang; He, Hui; Hsu, Andrew; Chen, Rongrong

    2013-11-01

    Carbon supported PdRu catalysts with various Pd:Ru atomic ratios were synthesized by impregnation method, and characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), electrochemical half-cell tests, and the anion-exchange membrane direct ethanol fuel cell (AEM-DEFC) tests. XRD results suggest that the PdRu metal exists on carbon support in an alloy form. TEM study shows that the bimetallic PdRu/C catalysts have slightly smaller average particle size than the single metal Pd/C catalyst. Lower onset potential and peak potential and much higher steady state current for ethanol oxidation in alkaline media were observed on the bimetallic catalysts (PdxRuy/C) than on the Pd/C, while the activity for ethanol oxidation on the pure Ru/C was not noticeable. By using Pd/C anode catalysts and MnO2 cathode catalysts, AEM-DEFCs free from the expensive Pt catalyst were assembled. The AEM DEFC using the bimetallic Pd3Ru/C anode catalyst showed a peak power density as high as 176 mW cm-2 at 80 °C, about 1.8 times higher than that using the single metal Pd/C catalyst. The role of Ru for enhancing the EOR activity of Pd/C catalysts is discussed.

  12. Exploring backbone-cation alkyl spacers for multi-cation side chain anion exchange membranes

    Science.gov (United States)

    Zhu, Liang; Yu, Xuedi; Hickner, Michael A.

    2018-01-01

    In order to systematically study how the arrangement of cations on the side chain and length of alkyl spacers between cations impact the performance of multi-cation AEMs for alkaline fuel cells, a series of polyphenylene oxide (PPO)-based AEMs with different cationic side chains were synthesized. This work resulted in samples with two or three cations in a side chain pendant to the PPO backbone. More importantly, the length of the spacer between cations varied from 3 methylene (-CH2-) (C3) groups to 8 methylene (C8) groups. The highest conductivity, up to 99 mS/cm in liquid water at room temperature, was observed for the triple-cation side chain AEM with pentyl (C5) or hexyl (C6) spacers. The multi-cation AEMs were found to have decreased water uptake and ionic conductivity when the spacer chains between cations were lengthened from pentyl (C5) or hexyl (C6) to octyl (C8) linking groups. The triple-cation membranes with pentyl (C5) or hexyl (C6) groups between cations showed greatest stability after immersion in 1 M NaOH at 80 °C for 500 h.

  13. Concentration-dependent effect of melatonin on DSPC membrane

    Science.gov (United States)

    Sahin, Ipek; Bilge, Duygu; Kazanci, Nadide; Severcan, Feride

    2013-11-01

    The concentration-induced effects of melatonin on distearoyl phosphatidylcholine (DSPC) model membranes were investigated by using two different non-invasive techniques, namely Fourier transform infrared (FTIR) spectroscopy and differential scanning calorimetry (DSC). An investigation of the Csbnd H, Cdbnd O and PO2- double bond stretching mode in FTIR spectra and DSC studies reveals that the inclusion of melatonin changes the physical properties of the DSPC multilamellar liposomes (MLVs) by shifting the main phase transition to lower temperatures, abolishing the pretransition, ordering the system in the gel phase and slightly disordering the system in the liquid crystalline phase, increasing the dynamics both in the gel phase and liquid crystalline phases. Melatonin also causes strong hydrogen bonding between Cdbnd O and PO2- groups of lipids and the water molecules around.

  14. Kinetics of growth of semi-spheric pittings in the vicinity repassivation potential depending on bulk concentration of activator anions

    International Nuclear Information System (INIS)

    Frejman, L.I.

    1985-01-01

    A general case of semi-spheric pittings development in aqueous solutions of electrolyte of NaCl or LiCl type at different values of C 0 , usually studied in the range approximately equal to 10 -5 -10 -3 g-ionxcm -3 (approximately equal to 10 -2 -10 0 g-ionxl -1 ), has been analyzed. On the basis of experimental data on participation of anion-activators and water molecules in the process of metal dissolution in pitting, and using the previously obtained equations, kinetics of open and closed semi-spheric pittings during galvanostatic anode polarization in neutral chloride solutions with different volumetric concentration of Cl - -ions (C 0 ) has been considered. In a general case the process kinetics is described by a complex equation, the boundary, more simple forms of which, correspond to the initial (A) and subsequent (B) stages of open pitting development, or to certain stable conditions of closed pitting development

  15. The effect of cation source and dietary cation-anion difference on rumen ion concentrations in lactating dairy cows.

    Science.gov (United States)

    Catterton, T L; Erdman, R A

    2016-08-01

    Many studies have focused on the influence of dietary cation-anion difference (DCAD) on animal performance but few have examined the effect of DCAD on the rumen ionic environment. The objective of this study was to examine the effects of DCAD, cation source (Na vs. K), and anion source (Cl vs. bicarbonate or carbonate) on rumen environment and fermentation. The study used 5 rumen-fistulated dairy cows and 5 dietary treatments that were applied using a 5×5 Latin square design with 2-wk experimental periods. Treatments consisted of (1) the basal total mixed ration (TMR); (2) the basal TMR plus 340mEq/kg of Na (dry matter basis) using NaCl; (3) the basal TMR plus 340mEq/kg of K using KCl; (4) the basal TMR plus 340mEq/kg of Na using NaHCO3; and (5) the basal TMR plus 340mEq/kg of K using K2CO3. On the last day of each experimental period, rumen samples were collected and pooled from 5 different locations at 0, 1.5, 3, 4.5, 6, 9, and 12h postfeeding for measurement of rumen pH and concentrations of strong ions and volatile fatty acids (VFA). Dietary supplementation of individual strong ions increased the corresponding rumen ion concentration. Rumen Na was decreased by 24mEq/L when K was substituted for Na in the diet, but added dietary Na had no effect on rumen K. Rumen Cl was increased by 10mEq/L in diets supplemented with Cl. Cation source had no effect on rumen pH or total VFA concentration. Increased DCAD increased rumen pH by 0.10 pH units and increased rumen acetate by 4mEq/L but did not increase total VFA. This study demonstrated that rumen ion concentrations can be manipulated by dietary ion concentrations. If production and feed efficiency responses to DCAD and ionophores in the diet are affected by rumen Na and K concentrations, then manipulating dietary Na and K could be used either to enhance or diminish those responses. Copyright © 2016 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

  16. Multivariate analysis of the transport in an ion exchange membrane bioreactor for removal of anionic micropollutants from drinking water.

    Science.gov (United States)

    Ricardo, A R; Velizarov, S; Crespo, J G; Reis, M A M

    2011-01-01

    The present study focuses on investigating the effects of biological compartment conditions on the transport of nitrate and perchlorate in an Ion Exchange Membrane Bioreactor (IEMB). In this hybrid process, the transport depends not only on the membrane properties but also on the biological compartment conditions. The experiments were planned according to the Plackett-Burman statistical design in order to cover a broader range of experimental conditions, under which a previously developed mechanistic transport model was not able to predict correctly the transport fluxes of the target pollutants. Using Principal Component Analysis, it was possible to identify not only the concentrations of target (nitrate and perchlorate) and of major driving counter-ion (chloride) but also those of some biomedium components (e.g. ammonia, ethanol and sulphate) as variables that affect the transport rate of micropollutants across the membrane. These conclusions are based on the loadings of the two first principal components that describe 84% of the data variance. The present study also revealed that the hydraulic retention time and the hydrodynamic conditions in the biocompartment have a minor contribution to the micropollutants transport. The results obtained are important for process optimization purposes.

  17. Process intensification on membrane-based process for blackcurrant juice concentration

    DEFF Research Database (Denmark)

    Fjerbæk Søtoft, Lene; Rong, Ben-Guang; Christensen, Knud Villy

    Juice concentrate production is a field where process intensification and novel concentration processes need to be implemented. The paper presents a systematic approach for process synthesis based on membrane processes for the concentration of blackcurrant juice, exemplified by the aroma recovery...... using combinations of vacuum membrane distillation and traditional distillation. Furthermore, the paper further suggests a novel method for the combination of nanofiltration, reverse osmosis and membrane distillation for the concentration of the dearomatized juice....

  18. Plant-Scale Concentration Column Designs for SHINE Target Solution Utilizing AG 1 Anion Exchange Resin

    Energy Technology Data Exchange (ETDEWEB)

    Stepinski, Dominique C. [Argonne National Lab. (ANL), Argonne, IL (United States); Vandegrift, G. F. [Argonne National Lab. (ANL), Argonne, IL (United States)

    2015-09-30

    Argonne is assisting SHINE Medical Technologies (SHINE) in their efforts to develop SHINE, an accelerator-driven process that will utilize a uranyl-sulfate solution for the production of fission product Mo-99. An integral part of the process is the development of a column for the separation and recovery of Mo-99, followed by a concentration column to reduce the product volume from 15-25 L to <1 L. Argonne has collected data from batch studies and breakthrough column experiments to utilize the VERSE (Versatile Reaction Separation) simulation program (Purdue University) to design plant-scale product recovery and concentration processes.

  19. Seasonal evolution of anionic, cationic and non-ionic surfactant concentrations in coastal aerosols from Askö, Sweden

    Science.gov (United States)

    Gérard, Violaine; Nozière, Barbara; Baduel, Christine

    2015-04-01

    Surfactants present in atmospheric aerosols are expected to enhance the activation into cloud droplets by acting on one of the two key parameters of the Köhler equation: the surface tension, σ. But because the magnitude of this effect and its regional and temporal variability are still highly uncertain [1,2], various approaches have been developed to evidence it directly in the atmosphere. This work presents the analysis of surfactants present in PM2.5 aerosol fractions collected at the coastal site of Askö, Sweden (58° 49.5' N, 17° 39' E) from July to October 2010. The total surfactant fraction was extracted from the samples using an improved double extraction technique. Surface tension measurements performed with the pendant drop technique [3] indicated the presence of very strong surfactants (σ ~ 30 - 35 mN/m) in these aerosols. In addition, these extractions were combined with colorimetric methods to determine the anionic, cationic and non-ionic surfactant concentrations [4,5], and provided for the first time interference-free surfactant concentrations in atmospheric aerosols. At this site, the total surfactant concentration in the PM2.5 samples varied between 7 to 150 mM and was dominated by anionic and non-ionic ones. The absolute surface tension curves obtained for total surfactant fraction displayed Critical Micelle Concentrations (CMC) in the range 50 - 400 uM, strongly suggesting a biological origin for the surfactants. The seasonal evolution of these concentrations and their relationships with environmental or meteorological parameters at the site will be discussed. [1] Ekström, S., Nozière, B. et al., Biogeosciences, 2010, 7, 387 [2] Baduel, C., Nozière, B., Jaffrezo, J.-L., Atmos. Environ., 2012, 47, 413 [3] Nozière, B., Baduel, C., Jaffrezo, J.-L., Nat. Commun., 2014, 5, 1 [4] Latif, M. T.; Brimblecombe, P. Environ. Sci. Technol., 2004, 38, 6501 [5] Pacheco e Silva et al., Method to measure surfactant in fluid, 2013, US 2013/0337568 A1

  20. Swelling dynamics of zwitterionic copolymers: The effects of concentration and type of anion and cation

    NARCIS (Netherlands)

    de Grooth, Joris; Ogieglo, Wojciech; de Vos, Wiebe Matthijs; Girones nogue, Miriam; Nijmeijer, Dorothea C.; Benes, Nieck Edwin

    2014-01-01

    The effect of different salts and their concentration on the swelling of zwitterionic copolymers has been investigated for bulk polymer samples as well as for thin films. Relatively low ratios of the zwitterionic monomer already radically change the swelling properties of the copolymer. Increasing

  1. The voltage-dependent anion selective channel 1 (VDAC1 topography in the mitochondrial outer membrane as detected in intact cell.

    Directory of Open Access Journals (Sweden)

    Marianna F Tomasello

    Full Text Available Voltage-Dependent Anion selective Channel maintains the permeability of the outer mitochondrial membrane and is relevant in bioenergetic metabolism and apoptosis. The structure of the protein was shown to be a β-barrel formed by 19 strands. The topology or sideness of the pore has been predicted with various approaches but a general consensus was never reached. This is an important issue since VDAC is considered receptor of Hexokinase and Bcl-2. We fused at VDAC1 C-terminus two tags separated by a caspase cleavage site. Activation in cellulo of caspases was used to eventually separate the two reporters. This experiment did not require the isolation of mitochondria and limited the possibility of outer membrane rupture due to similar procedures. Our results show that the C-terminus end of VDAC faces the mitochondrial inter-membrane space.

  2. Revealing mechanisms of selective, concentration-dependent potentials of 4-hydroxy-2-nonenal to induce apoptosis in cancer cells through inactivation of membrane-associated catalase.

    Science.gov (United States)

    Bauer, Georg; Zarkovic, Neven

    2015-04-01

    Tumor cells generate extracellular superoxide anions and are protected against superoxide anion-mediated intercellular apoptosis-inducing signaling by the expression of membrane-associated catalase. 4-Hydroxy-2-nonenal (4-HNE), a versatile second messenger generated during lipid peroxidation, has been shown to induce apoptosis selectively in malignant cells. The findings described in this paper reveal the strong, concentration-dependent potential of 4-HNE to specifically inactivate extracellular catalase of tumor cells both indirectly and directly and to consequently trigger apoptosis in malignant cells through superoxide anion-mediated intercellular apoptosis-inducing signaling. Namely, 4-HNE caused apoptosis selectively in NOX1-expressing tumor cells through inactivation of their membrane-associated catalase, thus reactivating subsequent intercellular signaling through the NO/peroxynitrite and HOCl pathways, followed by the mitochondrial pathway of apoptosis. Concentrations of 4-HNE of 1.2 µM and higher directly inactivated membrane-associated catalase of tumor cells, whereas at lower concentrations, 4-HNE triggered a complex amplificatory pathway based on initial singlet oxygen formation through H2O2 and peroxynitrite interaction. Singlet-oxygen-dependent activation of the FAS receptor and caspase-8 increased superoxide anion generation by NOX1 and amplification of singlet oxygen generation, which allowed singlet-oxygen-dependent inactivation of catalase. 4-HNE and singlet oxygen cooperate in complex autoamplificatory loops during this process. The finding of these novel anticancer pathways may be useful for understanding the role of 4-HNE in the control of malignant cells and for the optimization of ROS-dependent therapeutic approaches including antioxidant treatments. Copyright © 2015 Elsevier Inc. All rights reserved.

  3. Raman spectroscopic study of the aging and nitration of actinide processing anion-exchange resins in concentrated nitric acid

    International Nuclear Information System (INIS)

    Buscher, C. T.; Donohoe, R. J.; Mecklenburg, S. L.; Berg, J. M.; Tait, C. D.; Huchton, K. M.; Morris, D. E.

    1999-01-01

    Degradation of two types of anion exchange resins, Dowex 11 and Reillex HPQ, from the action of concentrated nitric acid (4 to 12 M) and radiolysis [from depleted uranium as UO 2 2+ nitrate species and 239 Pu as Pu(IV) nitrate species] was followed as a function of time with Raman vibrational spectroscopy. Elevated temperatures (∼50 degree sign C) were used in the absence of actinide metal loading to simulate longer exposures of the resin to a HNO 3 process stream and waste storage conditions. In the absence of actinide loading, only minor changes in the Dowex resin at acid concentrations ≤10 M were observed, while at 12 M acid concentration, the emergence of a Raman peak at 1345 cm-1 indicates the addition of nitro functional groups to the resin. Similar studies with the Reillex resin show it to be more resistant to nitric acid attack at all acid concentrations. Incorporation of weakly radioactive depleted uranium as the UO 2 2+ nitrate species to the ion-exchange sites of Dowex 11 under differing nitric acid concentrations (6 to 12 M) at room temperature showed no Raman evidence of resin degradation or nitration, even after several hundred days of contact. In contrast, Raman spectra for Dowex 11 in the presence of 239 Pu as Pu(IV) nitrate species reveal numerous changes indicating resin alterations, including a new mode at 1345 cm-1 consistent with a Pu(IV)-nitrate catalyzed addition of nitro groups to the resin backbone. (c) 2000 Society for Applied Spectroscopy

  4. Study of Concentrations of Available Cations and Anions in PM2.5 in the Air of Twelfth Region of Tehran City

    Directory of Open Access Journals (Sweden)

    Hossean Arfaeinia

    2017-04-01

    Full Text Available Background: In the last few decades, the city's air quality has become a major concern; especially there is strong evidence about health effects of particulate matter in urban communities.In addition to suspended particles concentration, the ionic part of suspended particles is also very important, So that some studies  ions like Sulfate is the reson of increasing the respiratory diseases.So the aim of this study was to study of concentration of PM2.5 particles and their ionic componentsincluding major anions and cations in twelfth region of Tehran city in 2013. Materials & Methods: This cross - sectional study was conducted in the air of twelfth region of Tehran. PM2.5 concentration was calculated with sampling by frmOMNITMAmbient Air Sampler with PTFE filter with a diameter of 47 mm and through the weight measurement.Concentration of anions and cations which had associated with PM2.5 particles was read after collected sample preparation and injection to device Ion Chromatography (IC Metrohm 850 model. Correlation matrix was calculated between anions and cations. Data analysis was carried out by Excel and SPSS version 18 and One-Way ANOVA test. Results: The mean daily concentration of PM2.5 particles was 19.41 µg/m3 during the study. One-Way ANOVA test showed a significant difference at the 0.05 level between PM2.5 concentrations on different days of the week. Concentrations for sodium, potassium, ammonium, calcium, magnesium, sulfate, nitrate, chloride were obtained 0.28, 0.06, 0.49, 0.87, 0.63, 56.3, 1.43 and 0.71 µg/m3, respectively, and no value was detected for fluoride and nitrite. Balance between anions and cations were calculated and the correlation coefficient (R2 were obtained 0.972 between the anions and cations. Conclusion The mean concentrations of PM2.5 was higher than the air standards in Iran and WHO guidelines (25 µg/m3 and EPA standards (35 µg/m3. In a study reported that the One-Way ANOVA test between particle

  5. Enhancement of encaged electron concentration by Sr(2+) doping and improvement of Gd(3+) emission through controlling encaged anions in conductive C12A7 phosphors.

    Science.gov (United States)

    Zhang, Meng; Liu, Yuxue; Zhu, Hancheng; Yan, Duanting; Yang, Jian; Zhang, Xinyang; Liu, Chunguang; Xu, Changshan

    2016-07-28

    Conductive C12A7:0.1%Gd(3+),y%Sr(2+) powders with different Sr(2+) doping concentrations have been prepared in a H2 atmosphere by a solid state method in combination with subsequent UV-irradiation. The encaged electron concentration could be modulated through tuning Sr(2+) doping and its maximum value reaches 2.3 × 10(19) cm(-3). This is attributed to the competition between enhanced uptake and the release of the encaged anions during their formation and diffusion processes and the suppression of encaged electrons generation due to the increased encaged OH(-) anions and the decreased encaged O(2-) anions. Although there exists encaged electrons and different encaged anions (O(2-), H(-) and OH(-)) in C12A7 conductive powders prepared through the hydrogen route, a dominant local environment around Gd(3+) could be observed using electron spin resonance (ESR) detection. It can be ascribed to the stronger coupling of the encaged OH(-) to the framework of C12A7 than those of the encaged electrons, O(2-) and H(-) anions. In addition, emission of Gd(3+) ions is enhanced under UV or low voltage electron beam excitation and a new local environment around Gd(3+) ions appears through the thermal annealing in air because of the decrease of the encaged OH(-) anions and the increase of the encaged O(2-) anions. Our results suggested that Sr(2+) doping in combination with thermal annealing in air is an effective strategy for increasing the conductive performance and enhancing the emission of rare earth ions doped into C12A7 conductive phosphors for low-voltage field emission displays (FEDs).

  6. Modeling and simulation of anion-exchange membrane chromatography for purification of Sf9 insect cell-derived virus-like particles.

    Science.gov (United States)

    Ladd Effio, Christopher; Hahn, Tobias; Seiler, Julia; Oelmeier, Stefan A; Asen, Iris; Silberer, Christine; Villain, Louis; Hubbuch, Jürgen

    2016-01-15

    Recombinant protein-based virus-like particles (VLPs) are steadily gaining in importance as innovative vaccines against cancer and infectious diseases. Multiple VLPs are currently evaluated in clinical phases requiring a straightforward and rational process design. To date, there is no generic platform process available for the purification of VLPs. In order to accelerate and simplify VLP downstream processing, there is a demand for novel development approaches, technologies, and purification tools. Membrane adsorbers have been identified as promising stationary phases for the processing of bionanoparticles due to their large pore sizes. In this work, we present the potential of two strategies for designing VLP processes following the basic tenet of 'quality by design': High-throughput experimentation and process modeling of an anion-exchange membrane capture step. Automated membrane screenings allowed the identification of optimal VLP binding conditions yielding a dynamic binding capacity of 5.7 mg/mL for human B19 parvovirus-like particles derived from Spodoptera frugiperda Sf9 insect cells. A mechanistic approach was implemented for radial ion-exchange membrane chromatography using the lumped-rate model and stoichiometric displacement model for the in silico optimization of a VLP capture step. For the first time, process modeling enabled the in silico design of a selective, robust and scalable process with minimal experimental effort for a complex VLP feedstock. The optimized anion-exchange membrane chromatography process resulted in a protein purity of 81.5%, a DNA clearance of 99.2%, and a VLP recovery of 59%. Copyright © 2015 Elsevier B.V. All rights reserved.

  7. A novel outer-membrane anion channel (porin) as part of a putatively two-component transport system for 4-toluenesulphonate in Comamonas testosteroni T-2

    OpenAIRE

    Mampel, Jörg; Maier, Elke; Tralau, Tewes; Ruff, Jürgen; Benz, Roland; Cook, Alasdair M.

    2004-01-01

    Inducible mineralization of TSA (4-toluenesulphonate) by Comamonas testosteroni T-2 is initiated by a secondary transport system, followed by oxygenation and oxidation by TsaMBCD to 4-sulphobenzoate under the regulation of TsaR and TsaQ. Evidence is presented for a novel, presumably two-component transport system (TsaST). It is proposed that TsaT, an outer-membrane porin, formed an anion-selective channel that works in co-operation with the putative secondary transporter, TsaS, located in the...

  8. Adsorption and Orientation of Human Islet Amyloid Polypeptide (hIAPP Monomer at Anionic Lipid Bilayers: Implications for Membrane-Mediated Aggregation

    Directory of Open Access Journals (Sweden)

    Guanghong Wei

    2013-03-01

    Full Text Available Protein misfolding and aggregation cause serious degenerative diseases, such as Alzheimer’s and type II diabetes. Human islet amyloid polypeptide (hIAPP is the major component of amyloid deposits found in the pancreas of type II diabetic patients. Increasing evidence suggests that β-cell death is related to the interaction of hIAPP with the cellular membrane, which accelerates peptide aggregation. In this study, as a first step towards understanding the membrane-mediated hIAPP aggregation, we investigate the atomic details of the initial step of hIAPP-membrane interaction, including the adsorption orientation and conformation of hIAPP monomer at an anionic POPG lipid bilayer by performing all-atom molecular dynamics simulations. We found that hIAPP monomer is quickly adsorbed to bilayer surface, and the adsorption is initiated from the N-terminal residues driven by strong electrostatic interactions of the positively-charged residues K1 and R11 with negatively-charged lipid headgroups. hIAPP binds parallel to the lipid bilayer surface as a stable helix through residues 7–22, consistent with previous experimental study. Remarkably, different simulations lead to the same binding orientation stabilized by electrostatic and H-bonding interactions, with residues R11, F15 and S19 oriented towards membrane and hydrophobic residues L12, A13, L16 and V17 exposed to solvent. Implications for membrane-mediated hIAPP aggregation are discussed.

  9. Effect of membrane protein concentration on binding of 3H-imipramine in human platelets

    International Nuclear Information System (INIS)

    Barkai, A.I.; Kowalik, S.; Baron, M.

    1985-01-01

    Binding of 3 H-imipramine to platelet membranes has been implicated as a marker for depression. Comparing 3 H-IMI binding between depressed patients and normal subjects we observed an increase in the dissociation constant Kd with increasing membrane protein. This phenomenon was studied more rigorously in five normal subjects. Platelet membranes were prepared and adjusted to four concentrations of protein ranging from 100 to 800 micrograms/ml. The 3 H-IMI binding parameters of maximum binding sites number (Bmax) and Kd were obtained by Scatchard analysis at each membrane concentration. A positive linear relationship was found between K/sub d/ values and the concentration of membrane protein in the assay, but no change was observed in Bmax. The variability in Kd values reported in the literature may be accounted for in part by the different concentrations of membrane protein used in various studies

  10. Effect of KOH Concentration and Anions on the Performance of a Ni-H2 Battery Positive Plate

    Science.gov (United States)

    Vaidyanathan, Hari; Robbins, Kathleen; Gopalakrishna, M. Rao

    1996-01-01

    The capacity and voltage behavior of electrochemically impregnated sintered nickel positive plates was examined by galvanostatic charging and discharging in a flooded electrolyte cell. Three different concentrations of potassium hydroxide (KOH) (40, 31, and 26 percent) and 31 percent KOH containing dissolved nitrate, sulfate, or silicate were investigated. The end-of-charge voltage at C/10 charge and at 10 degrees C showed the following order: 40 percent KOH greater than 31 percent KOH alone and in the presence of the anions greater than 26 percent KOH. The mid discharge voltage at C/2 discharge was higher in 26 percent KOH, almost the same for 31 percent KOH with and without added contaminants, and much lower for 40 percent KOH. The plate capacity was marginally affected by cycling in all cases except for 40 percent KOH, where the capacity declined after 1,000 cycles at 80 percent depth of discharge (DOD). At the end of cycling, all the plates tested experienced a weight loss, except in the case of 31 percent KOH, as a result of active material extrusion. Cyclic voltammetry of miniature electrodes in 31 percent KOH showed that the cathodic peak potentials are less polarized in the presence and absence of silicate at -5 degrees C compared to 25 degrees C indicating a slightly higher voltage during discharge in a Ni-H2 battery. Futhermore, the features of the current-potential profile were practically unchanged in the presence of silicate.

  11. Concentration gradient driven molecular dynamics: a new method for simulations of membrane permeation and separation.

    Science.gov (United States)

    Ozcan, Aydin; Perego, Claudio; Salvalaglio, Matteo; Parrinello, Michele; Yazaydin, Ozgur

    2017-05-01

    In this study, we introduce a new non-equilibrium molecular dynamics simulation method to perform simulations of concentration driven membrane permeation processes. The methodology is based on the application of a non-conservative bias force controlling the concentration of species at the inlet and outlet of a membrane. We demonstrate our method for pure methane, ethane and ethylene permeation and for ethane/ethylene separation through a flexible ZIF-8 membrane. Results show that a stationary concentration gradient is maintained across the membrane, realistically simulating an out-of-equilibrium diffusive process, and the computed permeabilities and selectivity are in good agreement with experimental results.

  12. Filter Membrane Effects on Water-Extractable Phosphorus Concentrations from Soil.

    Science.gov (United States)

    Norby, Jessica; Strawn, Daniel; Brooks, Erin

    2018-03-01

    To accurately assess P concentrations in soil extracts, standard laboratory practices for monitoring P concentrations are needed. Water-extractable P is a common analytical test to determine P availability for leaching from soils, and it is used to determine best management practices. Most P analytical tests require filtration through a filter membrane with 0.45-μm pore size to distinguish between particulate and dissolved P species. However, filter membrane type is rarely specified in method protocols, and many different types of membranes are available. In this study, three common filter membrane materials (polyether sulfone, nylon, and nitrocellulose), all with 0.45-μm pore sizes, were tested for analytical differences in total P concentrations and dissolved reactive P (DRP) concentrations in water extracts from six soils sampled from two regions. Three of the extracts from the six soil samples had different total P concentrations for all three membrane types. The other three soil extracts had significantly different total P results from at least one filter membrane type. Total P concentration differences were as great as 35%. The DRP concentrations in the extracts were dependent on filter type in five of the six soil types. Results from this research show that filter membrane type is an important parameter that affects concentrations of total P and DRP from soil extracts. Thus, membrane type should be specified in soil extraction protocols. Copyright © by the American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America, Inc.

  13. The Effect of Cellulose Acetate Concentration from Coconut Nira on Ultrafiltration Membrane Characters

    Science.gov (United States)

    Vaulina, E.; Widyaningsih, S.; Kartika, D.; Romdoni, M. P.

    2018-04-01

    Cellulose acetate is one of material in produce ultrafiltration membrane. Many efforts have been done to produce cellulose acetate from natural product to replace commercial one. In this research, ultrafiltration membrane has been produced from coconut flower water (nira). Ultrafiltration membrane is widely used in separation processes. This research aims to determine the characteristics of ultrafiltration membrane at a various concentration of cellulose acetate. The ultrafiltration membrane is conducted by phase inversion method at various concentration of cellulose acetate. The cellulose acetate concentration was 20%, 23% and 25% (w/w) with formamide as additives. The results showed that the greater the concentration of cellulose acetate, the smaller the flux value. The highest flux was a membrane with 20% cellulose acetate concentration with water flux value 55.34 L/(m2. h). But the greater the concentration of cellulose acetate the greater the rejection. The highest rejection value was on a membrane with 25% cellulose acetate concentration of 82.82%. While from the tensile strength test and the pore size analysis, the greater the cellulose acetate concentration the greater the tensile strength and the smaller the pore size

  14. Effect of solvent concentration on performance of polysulfone membrane for filtration and separation

    Science.gov (United States)

    Syafiq Mohamad Sofian, Muhamad; Zaini Yunos, Muhamad; Ahmad, Azlinnorazia; Harun, Zawati; Akhair, Siti Hajar Mohd; Adibah Raja Ahmad, Raja; Hafeez Azhar, Faiz; Rashid, Abdul Qaiyyum Abd; Ismail, Al Emran

    2017-08-01

    This study was conducted to investigate the effect of solvent concentration on the performance of polysulfone membrane via airbrush spray method. The solvent concentration was varied from 73% to 80% in dope solution. The study also investigated airbrush processing parameter such as spray time and distance at different solvent concentration. The prepared membrane was characterized in respect to its morphology and the performance of the membrane were evaluated via gas permeability performance. This study found that the membrane fiber size was reduced as solvent concentration increases. When time increased the diameter of fiber also increased. The distance also affected the fiber size, when the distance increased the diameter of fiber became smaller. 80% of solvent concentration has better filtration and separation ability compared to other solvent due to its porosity and morphology. From the gas permeability cell testing it shows that the permeability is increasing as the solvent concentration decrease.

  15. Effect of KOH concentration and anions on the performance of Ni-H2 battery positive plate

    Science.gov (United States)

    Vaidyanathan, H.; Robbins, Kathleen; Gopalakrishna, Rao M.

    1995-01-01

    The capacity and voltage behavior of electrochemically impregnated sintered nickel positive plates was examined by galavanostatic charging; and discharging in a flooded electrolyte cell. Three different concentrations of KOH (40 percent, 31 percent, and 26 percent) and 31 percent KOH containing dissolved nitrate, sulfate or silicate were investigated. The end of charge voltage at C/10 charge and at 10 C showed the following order: 40 percent KOH is greater than 31 percent KOH alone and in the presence of the anions greater than 26 percent KOE. The middischarge voltage at C/2 discharge was higher in 26 percent KOH, almost the same for 31 percent KOH with and without the added contaminants and much lower for 40 percent KOH. The plate capacity was marginally affected by cycling in all cases except for 40 percent KOH where the capacity declined after 1000 cycles at 80 percent DOD. At the end of cycling the plate tested in the presence of sulfate and silicate experienced measurable weight loss as a result of active material extrusion. Cyclic voltammetry of miniature electrodes in 31 percent KOH showed that the second oxidation peak that corresponds to the formation of a different phase of oxidized Ni has a lower peak current at -5 C compared to 25 C and oxygen evolution occurs a higher potential at -5 C. The reduction peak (discharge reaction) is more polarized at 25 C compared to -5 C. The presence of silicate alters the potentials only marginally. The implications of these results in plate treatment and low temperature operation are discussed.

  16. Butanol production from concentrated lactose/whey permeate: Use of pervaporation membrane to recover and concentrate product

    Science.gov (United States)

    In these studies butanol (acetone butanol ethanol, or ABE) was produced from concentrated lactose/whey permeate containing 211 gL-1 lactose. Fermentation of such a highly concentrated lactose solution was possible due to simultaneous product removal using a pervaporation membrane. In this system a p...

  17. Effect of ceramic membrane channel diameter on limiting retentate protein concentration during skim milk microfiltration.

    Science.gov (United States)

    Adams, Michael C; Barbano, David M

    2016-01-01

    Our objective was to determine the effect of retentate flow channel diameter (4 or 6mm) of nongraded permeability 100-nm pore size ceramic membranes operated in nonuniform transmembrane pressure mode on the limiting retentate protein concentration (LRPC) while microfiltering (MF) skim milk at a temperature of 50°C, a flux of 55 kg · m(-2) · h(-1), and an average cross-flow velocity of 7 m · s(-1). At the above conditions, the retentate true protein concentration was incrementally increased from 7 to 11.5%. When temperature, flux, and average cross-flow velocity were controlled, ceramic membrane retentate flow channel diameter did not affect the LRPC. This indicates that LRPC is not a function of the Reynolds number. Computational fluid dynamics data, which indicated that both membranes had similar radial velocity profiles within their retentate flow channels, supported this finding. Membranes with 6-mm flow channels can be operated at a lower pressure decrease from membrane inlet to membrane outlet (ΔP) or at a higher cross-flow velocity, depending on which is controlled, than membranes with 4-mm flow channels. This implies that 6-mm membranes could achieve a higher LRPC than 4-mm membranes at the same ΔP due to an increase in cross-flow velocity. In theory, the higher LRPC of the 6-mm membranes could facilitate 95% serum protein removal in 2 MF stages with diafiltration between stages if no serum protein were rejected by the membrane. At the same flux, retentate protein concentration, and average cross-flow velocity, 4-mm membranes require 21% more energy to remove a given amount of permeate than 6-mm membranes, despite the lower surface area of the 6-mm membranes. Equations to predict skim milk MF retentate viscosity as a function of protein concentration and temperature are provided. Retentate viscosity, retentate recirculation pump frequency required to maintain a given cross-flow velocity at a given retentate viscosity, and retentate protein

  18. An electro-active paper actuator made with cellulose–polypyrrole–ionic liquid nanocomposite: influence of ionic liquid concentration, type of anion and humidity

    International Nuclear Information System (INIS)

    Mahadeva, Suresha K; Kim, Jaehwan

    2010-01-01

    This paper reports a cellulose–polypyrrole–ionic liquid (CPIL) nanocomposite that can produce large actuating displacement in a low humidity environment. The fabrication process and actuator performance of the CPIL nanocomposite actuator are illustrated. Experimental results revealed that the size of anion, concentration of ionic liquid and ambient humidity level have a significant influence on the actuator performance of the CPIL nanocomposite. The bending displacement of the CPIL nanocomposite actuator was enhanced with increasing anion size, ionic liquid concentration and humidity level. CPIL nanocomposite made with 4% BMIBF 4 ionic liquid exhibited a very large bending displacement with excellent durability under ambient conditions (30% relative humidity and 25 °C). This is probably the first report that cellulose based electro-active paper actuator can exhibit such a large bending displacement under ambient conditions. Experimental results revealed that the proposed CPIL nanocomposite actuator under study can be operated up to 70% humidity level

  19. Forward osmosis - a novel membrane process for concentration of low level radioactive wastes

    International Nuclear Information System (INIS)

    Ghosh, A.K.; Bindal, R.C.; Tewari, P.K.

    2013-01-01

    Forward osmosis (FO) is an emerging membrane process in which osmotic pressure differential across a semi-permeable membrane between the solution to be concentrated (feed) and a concentrated solution of high osmotic pressure (draw solution) than the feed is used to effect separation of water from dissolved solutes. With time, feed stream gets concentrated with dilution of draw solution and this technology recently being used as more energy efficient alternative to reverse osmosis (RO) in some of the application areas, particularly for the concentration of low volume high value products. The use of pressure driven membrane processes like reverse osmosis (RO) and ultrafiltration (UF) are already demonstrated in the treatment of radioactive laundry, laboratory effluents and some other applications in nuclear industry. The application of FO membrane process to concentrate simulated inactive ammonium-diuranate (ADU) filtered effluent solution (by mixing uranyl nitrate and ammonium nitrate) using indigenously developed cellulose acetate (CA) and thin-film composite polyamide (TFCP) membranes has been published recently from our laboratory. In this presentation, we briefly discuss our views on possibility of using FO membrane process with proper selection of membrane for concentration of low level radioactive wastes generated in various steps of nuclear fuel cycle in most effective way. (author)

  20. Novel use of positively charged nylon transfer membranes for trapping indoleacetic acid or other small anions during efflux from plant tissues

    Science.gov (United States)

    Evans, M. L.; Hangarter, R. P.

    1993-01-01

    Positively charged nylon blotting membranes were used as an anion binding medium to trap [14C]indoleactic acid (IAA) as it exited cells at the basal ends of Coleus blumei L. stem and Zea mays L. coleoptile segments. Autoradiography was used to visualize where the [14C] that moved out of the cut ends was localized on the nylon membrane. Diffusion of [14C]IAA from the initial point of contact with the nylon membrane was minimal. Comparison of the autoradiograms with anatomical tissue prints of the cut ends of the segments was used to determine what tissues participate in IAA movement. The results of these initial studies were consistent with other reports suggesting that [14C]IAA movement was primarily associated with vascular tissues in both C. blumei stems and corn coleoptiles, but the resolution was not sufficient to identify which vascular tissues were involved in IAA transport. With further refinements, this technique could also be used for studying the movement of other small charged molecules through plant tissues.

  1. Investigation of microbial adaptation to salinity variation for treatment of reverse osmosis concentrate by membrane bioreactor

    DEFF Research Database (Denmark)

    Jang, Duksoo; Moon, Chungman; Ahn, Kyuhong

    2014-01-01

    quantitative study on a microbial adaptation strategy for variations on salt concentration (0–20 g/L), lab-scale membrane bioreactors (7L working volume) with polypropylene hollow fiber membrane module (pore size 0.4 μm) were used with different adaptation strategies: instant and stepwise mode. The performance...

  2. Membrane distillation with porous metal hollow fibers for the concentration of thermo-sensitive solutions

    NARCIS (Netherlands)

    Shukla, Sushumna

    2014-01-01

    This thesis presents an original approach for the concentration of thermo-sensitive solutions: the Sweep Gas Membrane Distillation (SGMD) process. A new membrane contactor with metallic hollow fibers has been designed and allows the distillation process to be operational at low temperature. Heat is

  3. Direct Numerical Simulations of Concentration and Temperature Polarization in Direct Contact Membrane Distillation

    Science.gov (United States)

    Lou, Jincheng; Tilton, Nils

    2017-11-01

    Membrane distillation (MD) is a method of desalination with boundary layers that are challenging to simulate. MD is a thermal process in which warm feed and cool distilled water flow on opposite sides of a hydrophobic membrane. The temperature difference causes water to evaporate from the feed, travel through the membrane, and condense in the distillate. Two challenges to MD are temperature and concentration polarization. Temperature polarization represents a reduction in the transmembrane temperature difference due to heat transfer through the membrane. Concentration polarization describes the accumulation of solutes near the membrane. These phenomena reduce filtration and lead to membrane fouling. They are difficult to simulate due to the coupling between the velocity, temperature, and concentration fields on the membrane. Unsteady regimes are particularly challenging because noise at the outlets can pollute the near-membrane flow fields. We present the development of a finite-volume method for the simulation of fluid flow, heat, and mass transport in MD systems. Using the method, we perform a parametric study of the polarization boundary layers, and show that the concentration boundary layer shows self-similar behavior that satisfies power laws for the downstream growth. Funded by the U.S. Bureau of Reclamation.

  4. Combined effect of salt concentration and pressure gradients across charged membranes

    DEFF Research Database (Denmark)

    Benavente, Juana; Jonsson, Gunnar Eigil

    2002-01-01

    The combined effect of both concentration and pressure differences on electrical potential (Deltaphi) for two ion-exchanger membranes, one positively charged (AE) and another negatively charged (CE), measured with the membranes in contact with NaCl solutions was studied. Results show a linear dep...

  5. An integrated membrane bioreactor - nanofiltration concept with concentrate recirculation for wastewater treatment and nutrient recovery

    NARCIS (Netherlands)

    Kappel, C.

    2014-01-01

    Increasing water shortages drive the need for water reuse. Membranes are a very suitable technology for purification of wastewater. Membrane bioreactor (MBR) permeate can be polished by nanofiltration (NF), allowing the production of high quality reusable water. The NF concentrate potentially is an

  6. Monitoring changes in membrane polarity, membrane integrity, and intracellular ion concentrations in Streptococcus pneumoniae using fluorescent dyes.

    Science.gov (United States)

    Clementi, Emily A; Marks, Laura R; Roche-Håkansson, Hazeline; Håkansson, Anders P

    2014-02-17

    Membrane depolarization and ion fluxes are events that have been studied extensively in biological systems due to their ability to profoundly impact cellular functions, including energetics and signal transductions. While both fluorescent and electrophysiological methods, including electrode usage and patch-clamping, have been well developed for measuring these events in eukaryotic cells, methodology for measuring similar events in microorganisms have proven more challenging to develop given their small size in combination with the more complex outer surface of bacteria shielding the membrane. During our studies of death-initiation in Streptococcus pneumoniae (pneumococcus), we wanted to elucidate the role of membrane events, including changes in polarity, integrity, and intracellular ion concentrations. Searching the literature, we found that very few studies exist. Other investigators had monitored radioisotope uptake or equilibrium to measure ion fluxes and membrane potential and a limited number of studies, mostly in Gram-negative organisms, had seen some success using carbocyanine or oxonol fluorescent dyes to measure membrane potential, or loading bacteria with cell-permeant acetoxymethyl (AM) ester versions of ion-sensitive fluorescent indicator dyes. We therefore established and optimized protocols for measuring membrane potential, rupture, and ion-transport in the Gram-positive organism S. pneumoniae. We developed protocols using the bis-oxonol dye DiBAC4(3) and the cell-impermeant dye propidium iodide to measure membrane depolarization and rupture, respectively, as well as methods to optimally load the pneumococci with the AM esters of the ratiometric dyes Fura-2, PBFI, and BCECF to detect changes in intracellular concentrations of Ca(2+), K(+), and H(+), respectively, using a fluorescence-detection plate reader. These protocols are the first of their kind for the pneumococcus and the majority of these dyes have not been used in any other bacterial

  7. Drug Clearance from Cerebrospinal Fluid Mediated by Organic Anion Transporters 1 (Slc22a6) and 3 (Slc22a8) at Arachnoid Membrane of Rats.

    Science.gov (United States)

    Zhang, Zhengyu; Tachikawa, Masanori; Uchida, Yasuo; Terasaki, Tetsuya

    2018-03-05

    Although arachnoid mater epithelial cells form the blood-arachnoid barrier (BAB), acting as a blood-CSF interface, it has been generally considered that the BAB is impermeable to water-soluble substances and plays a largely passive role. Here, we aimed to clarify the function of transporters at the BAB in regulating CSF clearance of water-soluble organic anion drugs based on quantitative targeted absolute proteomics (QTAP) and in vivo analyses. Protein expression levels of 61 molecules, including 19 ATP-binding-cassette (ABC) transporters and 32 solute-carrier (SLC) transporters, were measured in plasma membrane fraction of rat leptomeninges using QTAP. Thirty-three proteins were detected; others were under the quantification limits. Expression levels of multidrug resistance protein 1 (Mdr1a/P-gp/Abcb1a) and breast cancer resistance protein (Bcrp/Abcg2) were 16.6 and 3.27 fmol/μg protein (51.9- and 9.82-fold greater than in choroid plexus, respectively). Among those organic anion transporters detected only at leptomeninges, not choroid plexus, organic anion transporter 1 (oat1/Slc22a6) showed the greatest expression (2.73 fmol/μg protein). On the other hand, the protein expression level of oat3 at leptomeninges was 6.65 fmol/μg protein, and the difference from choroid plexus was within two-fold. To investigate oat1's role, we injected para-aminohippuric acid (PAH) with or without oat1 inhibitors into cisterna magna (to minimize the contribution of choroid plexus function) of rats. A bulk flow marker, FITC-inulin, was not taken up from CSF up to 15 min, whereas uptake clearance of PAH was 26.5 μL/min. PAH uptake was completely blocked by 3 mM cephalothin (inhibits both oat1 and oat3), while 17% of PAH uptake was inhibited by 0.2 mM cephalothin (selectively inhibits oat3). These results indicate that oat1 and oat3 at the BAB provide a distinct clearance pathway of organic anion drugs from CSF independently of choroid plexus.

  8. Methane-steam reforming by molten salt - membrane reactor using concentrated solar thermal energy

    International Nuclear Information System (INIS)

    Watanuki, K.; Nakajima, H.; Hasegawa, N.; Kaneko, H.; Tamaura, Y.

    2006-01-01

    By utilization of concentrated solar thermal energy for steam reforming of natural gas, which is an endothermic reaction, the chemical energy of natural gas can be up-graded. The chemical system for steam reforming of natural gas with concentrated solar thermal energy was studied to produce hydrogen by using the thermal storage with molten salt and the membrane reactor. The original steam reforming module with hydrogen permeable palladium membrane was developed and fabricated. Steam reforming of methane proceeded with the original module with palladium membrane below the decomposition temperature of molten salt (around 870 K). (authors)

  9. Electrodeposition of ZnO from DMSO solution: influence of anion nature and its concentration in the nucleation and growth mechanisms

    Energy Technology Data Exchange (ETDEWEB)

    Riveros, Gonzalo; Ramirez, Daniel, E-mail: gonzalo.riveros@uv.cl [Departamento de Quimica y Bioquimica, Facultad de Ciencias, Universidad de Valparaiso, Valparaiso (Chile); Tello, Alejandra; Schrebler, Ricardo; Henriquez, Rodrigo; Gomez, Humberto [Instituto de Quimica, Pontificia Universidad Catolica de Valparaiso, Curauma, Valparaiso (Chile)

    2012-03-15

    The influence of the anion nature and its concentration in the electrodeposition of ZnO onto a gold electrode from dimethylsulfoxide (DMSO) solutions was studied. Voltammetric experiments revealed important changes in the zinc oxide electrodeposition process depending on the employed anion as electrolyte. From chronoamperometric experiments, the corresponding current-time curves were fitted with different nucleation and growth mechanism models. The analysis of these results showed changes from an instantaneous to a progressive growth when the solution composition was changed from ZnCl{sub 2} to ZnCl{sub 2} + LiCl. The change of the mechanism is associated to the adsorption of chloride ion on the active sites of the electrode surface when LiCl is present in the solution. (author)

  10. Effect of antibody charge and concentration on deposition of antibody to glomerular basement membrane

    International Nuclear Information System (INIS)

    Madaio, M.P.; Salant, D.J.; Adler, S.; Darby, C.; Couser, W.G.

    1984-01-01

    Fixed anionic sites within the glomerular capillary wall influence the permeation of serum proteins, the localization of various antigens, and the deposition of antibody in the subepithelial space. In anti-GBM nephritis antibody deposition occurs very rapidly to antigenic sites located relatively proximal in the glomerular capillary wall. The authors examined the influence of the glomerular charge barrier on anti-GBM antibody deposition by comparing the rate of deposition of antibodies with cationic and anionic isoelectric points. Purified sheep anti-rat GBM IgG was isolated from acid eluates of kidneys obtained 24 hr after rats were injected with sheep antiserum to rat GBM. Anti-GBM IgG was separated into cationic (pI 6.4-8.5) and anionic (pI 4.2-6.8) fractions, which were radiolabelled with 131 I and 125 I, respectively, shown to have equal antibody contents measured by in vitro binding to normal glomeruli, mixed in equal amounts, and injected in incremental doses to ten rats. At 1 hr the glomerular antibody binding of each fraction was directly related to the blood level (r . 0.95, r . 0.97) and delivery of antibody (r . 0.98, r . 0.98). Glomerular binding of cationic antibody was four times greater than anionic antibody over the entire range of deliveries studied (P less than 0.001). The authors conclude that glomerular deposition of anti-GBM antibody is directly related to blood concentration and delivery of antibody. Furthermore, the deposition of cationic antibodies to GBM antigens was significantly greater than the deposition of anionic antibodies

  11. Simultaneous micro-electromembrane extractions of anions and cations using multiple free liquid membranes and acceptor solutions

    Czech Academy of Sciences Publication Activity Database

    Kubáň, Pavel; Boček, Petr

    2016-01-01

    Roč. 908, FEB (2016), s. 113-120 ISSN 0003-2670 R&D Projects: GA ČR(CZ) GA13-05762S Institutional support: RVO:68081715 Keywords : free liquid membranes * micro-electromembrane extraction * simultaneous extractions Subject RIV: CB - Analytical Chemistry , Separation Impact factor: 4.950, year: 2016

  12. Extractable substances (anionic surfactants) from membrane filters induce morphological changes in the green alga Scenedesmus obliquus (Chlorophyceae)

    NARCIS (Netherlands)

    Lürling, M.; Beekman, W.

    2002-01-01

    The effect of filtration of medium through different kinds of filters (glass fiber, mixed esters of cellulose and nitrocellulose) on the morphology in the green alga Scenedesmus obliquus was examined. Several compounds potentially released from membrane filters were further investigated, and among

  13. Simultaneous micro-electromembrane extractions of anions and cations using multiple free liquid membranes and acceptor solutions

    Czech Academy of Sciences Publication Activity Database

    Kubáň, Pavel; Boček, Petr

    2016-01-01

    Roč. 908, FEB (2016), s. 113-120 ISSN 0003-2670 R&D Projects: GA ČR(CZ) GA13-05762S Institutional support: RVO:68081715 Keywords : free liquid membranes * micro-electromembrane extraction * simultaneous extractions Subject RIV: CB - Analytical Chemistry, Separation Impact factor: 4.950, year: 2016

  14. Local membrane deformations activate Ca2+-dependent K+ and anionic currents in intact human red blood cells

    DEFF Research Database (Denmark)

    Dyrda, Agnieszka; Cytlak, Urszula; Ciuraszkiewicz, Anna

    2010-01-01

    -activated transient PCa observed here under local membrane deformation is a likely contributor to the Ca(2+)-mediated effects observed during the normal aging process of red blood cells, and to the increased Ca(2+) content of red cells in certain hereditary anemias such as thalassemia and sickle cell anemia....

  15. Impact of ozonation, anion exchange resin and UV/H2O2 pre-treatments to control fouling of ultrafiltration membrane for drinking water treatment.

    Science.gov (United States)

    Pramanik, Biplob Kumar; Pramanik, Sagor Kumar; Sarker, Dipok Chandra; Suja, Fatihah

    2017-06-01

    The effects of ozonation, anion exchange resin (AER) and UV/H 2 O 2 were investigated as a pre-treatment to control organic fouling (OF) of ultrafiltration membrane in the treatment of drinking water. It was found that high molecular weight (MW) organics such as protein and polysaccharide substances were majorly responsible for reversible fouling which contributed to 90% of total fouling. The decline rate increased with successive filtration cycles due to deposition of protein content over time. All pre-treatment could reduce the foulants of a Ultrafiltration membrane which contributed to the improvement in flux, and there was a greater improvement of flux by UV/H 2 O 2 (61%) than ozonation (43%) which in turn was greater than AER (23%) treatment. This was likely due to the effective removal/breakdown of high MW organic content. AER gave greater removal of biofouling potential components (such as biodegradable dissolved organic carbon and assimilable organic carbon contents) compared to UV/H 2 O 2 and ozonation treatment. Overall, this study demonstrated the potential of pre-treatments for reducing OF of ultrafiltration for the treatment of drinking water.

  16. An alternative anionic bio-sustainable anti-fungal agent: Investigation of its mode of action on the fungal cell membrane.

    Science.gov (United States)

    Stenbæk, Jonas; Löf, David; Falkman, Peter; Jensen, Bo; Cárdenas, Marité

    2017-07-01

    The potential of a lactylate (the sodium caproyl lactylate or C10 lactylate), a typical food grade emulsifier, as an anionic environmental friendly anti-fungal additive was tested in growth medium and formulated in a protective coating for exterior wood. Different laboratory growth tests on the blue stain fungus Aureobasidium pullulans were performed and its interactions on a model fungal cell membrane were studied. Promising short term anti-fungal effects in growth tests were observed, although significant but less dramatic effects took place in coating test on wood panels. Scanning electron microscope analysis shows clear differences in the amount of fungal slime on the mycelium of Aureobasidium pullulans when the fungus was exposed of C10 lactylate. This could indicate an effect on the pullulan and melanin production by the fungus. Moreover, the interaction studies on model fungal cell membranes show that C10 lactylate affects the phospholipid bilayer in a similar manner to other negative charged detergents. Copyright © 2017 Elsevier Inc. All rights reserved.

  17. A Pd/C-CeO2 Anode Catalyst for High-Performance Platinum-Free Anion Exchange Membrane Fuel Cells.

    Science.gov (United States)

    Miller, Hamish A; Lavacchi, Alessandro; Vizza, Francesco; Marelli, Marcello; Di Benedetto, Francesco; D'Acapito, Francesco; Paska, Yair; Page, Miles; Dekel, Dario R

    2016-05-10

    One of the biggest obstacles to the dissemination of fuel cells is their cost, a large part of which is due to platinum (Pt) electrocatalysts. Complete removal of Pt is a difficult if not impossible task for proton exchange membrane fuel cells (PEM-FCs). The anion exchange membrane fuel cell (AEM-FC) has long been proposed as a solution as non-Pt metals may be employed. Despite this, few examples of Pt-free AEM-FCs have been demonstrated with modest power output. The main obstacle preventing the realization of a high power density Pt-free AEM-FC is sluggish hydrogen oxidation (HOR) kinetics of the anode catalyst. Here we describe a Pt-free AEM-FC that employs a mixed carbon-CeO2 supported palladium (Pd) anode catalyst that exhibits enhanced kinetics for the HOR. AEM-FC tests run on dry H2 and pure air show peak power densities of more than 500 mW cm(-2) . © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  18. Durability and Performance of Polystyrene-b-Poly(vinylbenzyl trimethylammonium) Diblock Copolymer and Equivalent Blend Anion Exchange Membranes

    Science.gov (United States)

    2015-01-01

    requiring circulation of the electrolyte to filter out the carbonate solids. The superior power density of proton exchange membrane fuel cells ( PEMFC ...without requir- ing a CO2 free oxidant stream, prevented commercial develop- ment of the liquid AFC, allowing PEMFCs to dominate low temperature fuel...cell research and development. PEMFCs employ a solid acidic polymer to transport protons from anode to cathode. PEMs have been researched heavily the

  19. Fouling-Resistant Membranes for Treating Concentrated Brines for Water Reuse in Advanced Energy Systems

    Energy Technology Data Exchange (ETDEWEB)

    Hendren, Zachary [RTI International, Research Triangle Park, NC (United States); Choi, Young Chul [RTI International, Research Triangle Park, NC (United States)

    2014-10-14

    The high total dissolved solids (TDS) levels in the wastewater quality generated from unconventional oil and gas development make the current state-of-the art approach to water treatment/disposal untenable. Our proposed membrane technology approach addresses the two major challenges associated with this water: 1) the membrane distillation process removes the high TDS content, which is often 8 times higher than that of seawater, and 2) our novel membrane coating prevents the formation of scale that would otherwise pose a significant operational hurdle. This is accomplished through next-generation electrically conductive membranes that mitigate fouling beyond what is currently possible, and allow for the flexibility to treat to the water to levels desirable for multiple reuse options, thus reducing fresh water withdrawal, all the way to direct disposal into the environment. The overall project objective was to demonstrate the efficacy of membrane distillation (MD) as a cost-savings technology to treat concentrated brines (such as, but not limited to, produced waters generated from fossil fuel extraction) that have high levels of TDS for beneficial water reuse in power production and other industrial operations as well as agricultural and municipal water uses. In addition, a novel fouling-resistant nanocomposite membrane was developed to reduce the need for chemicals to address membrane scaling due to the precipitation of divalent ions in high-TDS waters and improve overall MD performance via an electrically conductive membrane distillation process (ECMD). This anti-fouling membrane technology platform is based on incorporating carbon nanotubes (CNTs) into the surface layer of existing, commercially available MD membranes. The CNTs impart electrical conductivity to the membrane surface to prevent membrane scaling and fouling when an electrical potential is applied.

  20. Anion exchange chromatography of 99mTc(Sn)-EHDP complexes: determination of the charge of the components and influence of pH and ligand concentration

    International Nuclear Information System (INIS)

    Huigen, Y.M.; Diender, M.; Gelsema, W.J.; De Ligny, C.L.

    1991-01-01

    The components of a 99m Tc(Sn)-EHDP complex mixture were separated by means of normal pressure and high-pressure anion exchange chromatography. Precautions were taken to prevent the dissociation of the complexes during chromatography. The charges of the components were determined according to the methods of Wilson and Pinkerton (1985) and Russell and Bischoff (1985). The values of the charges obtained with the two methods are not in agreement. Russell and Bischoff's method, in which a reference ion is used, must be preferred. However, even with this method the accuracy of the data obtained is probably limited, due to the difficulty of making corrections for activity coefficients of highly-charge ions at the rather high electrolyte concentrations that must be used in the ion exchange method. So, we think that it is only warranted to conclude that the mean charge of the components of 99m Tc(Sn)-EHDP is about -6 at pH 7, and that the charges of the individual components are in the range of -4 to -9. The influence of pH and ligand concentration in the reaction mixture was determined with high pressure anion exchange chromatography. It was found that a decrease in the pH of the reaction mixture favours the production of complexes with a long retention time, which leads to a slightly higher mean charge. The ligand concentration of the reaction mixture scarcely influenced the relative concentrations of the components. (author)

  1. Optimization of SHINE Process: Design and Verification of Plant-Scale AG 1 Anion-Exchange Concentration Column and Titania Sorbent Pretreatment

    Energy Technology Data Exchange (ETDEWEB)

    Stepinski, Dominique C. [Argonne National Lab. (ANL), Argonne, IL (United States). Nuclear Engineering Division; Abdul, Momen [Argonne National Lab. (ANL), Argonne, IL (United States). Nuclear Engineering Division; Youker, Amanda J. [Argonne National Lab. (ANL), Argonne, IL (United States). Nuclear Engineering Division; Rotsch, David A. [Argonne National Lab. (ANL), Argonne, IL (United States). Nuclear Engineering Division; Tkac, Peter [Argonne National Lab. (ANL), Argonne, IL (United States). Nuclear Engineering Division; Chemerisov, Sergey [Argonne National Lab. (ANL), Argonne, IL (United States). Nuclear Engineering Division; Vandegrift, George F. [Argonne National Lab. (ANL), Argonne, IL (United States). Nuclear Engineering Division

    2016-06-01

    Argonne National Laboratory has developed a Mo-recovery and -purification system for the SHINE medical technologies process, which uses a uranyl sulfate solution for the accelerator-driven production of Mo-99. The objective of this effort is to reduce the processing time for the acidification of the Mo-99 product prior to loading onto a concentration column and concentration of the Mo-99 product solution. Two methods were investigated: (1) the replacement of the titania concentration column by an anion-exchange column to decrease processing time and increase the radioiodine-decontamination efficiency and (2) pretreatment of the titania sorbent to improve its effectiveness for the Mo-recovery and -concentration columns. Promising results are reported for both methods.

  2. Trough Concentrations of Vancomycin in Patients Undergoing Extracorporeal Membrane Oxygenation.

    Directory of Open Access Journals (Sweden)

    So Jin Park

    Full Text Available To investigate the appropriateness of the current vancomycin dosing strategy in adult patients with extracorporeal membrane oxygenation (ECMO, between March 2013 and November 2013, patients who were treated with vancomycin while on ECMO were enrolled. Control group consisted of 60 patients on vancomycin without ECMO, stayed in medical intensive care unit during the same study period and with the same exclusion criteria. Early trough levels were obtained within the fourth dosing, and maintenance levels were measured at steady state. A total of 20 patients were included in the analysis in ECMO group. Sixteen patients received an initial intravenous dose of 1.0 g vancomycin followed by 1.0 g every 12 hours. The non-steady state trough level of vancomycin after starting administration was subtherapeutic in 19 patients (95.00% in ECMO group as compared with 40 patients (66.67% in the control group (p = 0.013. Vancomycin clearance was 1.27±0.51 mL/min/kg, vancomycin clearance/creatinine clearance ratio was 0.90 ± 0.37, and elimination rate constant was 0.12 ± 0.04 h-1. Vancomycin dosingfrequency and total daily dose were significantly increased after clinical pharmacokinetic services of the pharmacist based on calculated pharmacokinetic parameters (from 2.10 ± 0.72 to 2.90 ± 0.97 times/day, p = 0.002 and from 32.54 ± 8.43 to 42.24 ± 14.62mg/kg, p = 0.014 in ECMO group in contrast with those (from 2.11 ± 0.69 to 2.37 ± 0.86 times/day, p = 0.071 and from 33.91 ± 11.85 to 31.61 ± 17.50 mg/kg, p = 0.350 in the control group.Although the elimination rate for vancomycin was similar with population parameter of non ECMO patients, the current dosing strategy of our institution for vancomycinin our ICU was not sufficient to achieve the target trough in the initial period in most patients receiving ECMO.

  3. Effect of polysulfone concentration on the performance of membrane-assisted lead acid battery

    Directory of Open Access Journals (Sweden)

    Ahmad Fauzi Ismail

    2002-11-01

    Full Text Available The application of lead acid battery in tropical countries normally faces the problem of water decomposition. This phenomenon is due to the factor of charge-discharge reaction in the battery and heat accumulation caused by hot tropical climate and heat generated from engine compartment. The objective of this study is to analyze the effect of polysulfone concentration on the performance of membrane-assisted lead-acid battery. Gas separation membranes, prepared through wet-dry phase inversion method and using various polysulfone concentrated formulations, were applied on the battery vent holes, for the purpose of preventing electrolyte from evaporating to the atmosphere. The best membrane, which retains the most electrolyte, will be chosen to be applied on the soon-to-be-developed “membrane-assisted maintenance- free battery”. This maintenance-free battery will need no topping up of deionized water every time the electrolyte level goes low.

  4. Double-Skinned Forward Osmosis Membranes for Reducing Internal Concentration Polarization within the Porous Sublayer

    KAUST Repository

    Wang, Kai Yu

    2010-05-19

    A scheme to fabricate forward osmosis membranes comprising a highly porous sublayer sandwiched between two selective skin layers via phase inversion was proposed. One severe deficiency of existing composite and asymmetric membranes used in forward osmosis is the presence of unfavorable internal concentration polarization within the porous support layer that hinders both (i) separation (salt flux) and (ii) the performance (water flux). The double skin layers of the tailored membrane may mitigate the internal concentration polarization by preventing the salt and other solutes in the draw solution from penetrating into the membrane porous support. The prototype double-skinned cellulose acetate membrane displayed a water flux of 48.2 L·m-2·h -1 and lower reverse salt transport of 6.5 g·m -2·h-1 using 5.0 M MgCl2 as the draw solution in a forward osmosis process performed at 22 °C. This can be attributed to the effective salt rejection by the double skin layers and the low water transport resistance within the porous support layer. The prospects of utilizing the double-selective layer membranes may have potential application in forward osmosis for desalination. This study may help pave the way to improve the membrane design for the forward osmosis process. © 2010 American Chemical Society.

  5. Double-Skinned Forward Osmosis Membranes for Reducing Internal Concentration Polarization within the Porous Sublayer

    KAUST Repository

    Wang, Kai Yu; Ong, Rui Chin; Chung, Tai-Shung

    2010-01-01

    A scheme to fabricate forward osmosis membranes comprising a highly porous sublayer sandwiched between two selective skin layers via phase inversion was proposed. One severe deficiency of existing composite and asymmetric membranes used in forward osmosis is the presence of unfavorable internal concentration polarization within the porous support layer that hinders both (i) separation (salt flux) and (ii) the performance (water flux). The double skin layers of the tailored membrane may mitigate the internal concentration polarization by preventing the salt and other solutes in the draw solution from penetrating into the membrane porous support. The prototype double-skinned cellulose acetate membrane displayed a water flux of 48.2 L·m-2·h -1 and lower reverse salt transport of 6.5 g·m -2·h-1 using 5.0 M MgCl2 as the draw solution in a forward osmosis process performed at 22 °C. This can be attributed to the effective salt rejection by the double skin layers and the low water transport resistance within the porous support layer. The prospects of utilizing the double-selective layer membranes may have potential application in forward osmosis for desalination. This study may help pave the way to improve the membrane design for the forward osmosis process. © 2010 American Chemical Society.

  6. Time and spatial concentration profile inside a membrane by means of a memory formalism

    Science.gov (United States)

    Caputo, Michele; Cametti, Cesare; Ruggero, Vittorio

    2008-03-01

    In this note, the profile concentration of diffusing particles inside a membrane has been calculated on the basis of the Fick diffusion equation modified by introducing a memory formalism. In highly heterogeneous systems, such as biological membranes, the intrinsic structural complexity of the medium restricts the applicability of continuum diffusion models and suggests that diffusion parameters could depend at a certain time or position on what happens at preceding times (diffusion with memory). Here, we deal with two particular cases, the diffusion of glucose across an erythrocyte membrane, when the concentration at both sides of the membrane are assigned, and the permeation transport of small molecular weight solute through an artificial hydrogel polymeric membrane. However, the present procedure can be easily extended to more general conditions. The knowledge of the concentration profile within a membranous structure, which is usually not easily experimentally accessible, completes the description of the rather complex phenomenon of the transport across a highly structured confined medium and can also lead to an improvement in controlled drug-delivery systems.

  7. Membrane distillation for wastewater reverse osmosis concentrate treatment with water reuse potential

    KAUST Repository

    Naidu, Gayathri

    2016-11-29

    Membrane distillation (MD) was evaluated as a treatment option of wastewater reverse osmosis concentrate (WWROC) discharged from wastewater reclamation plants (WRPs). A direct contact MD (DCMD), at obtaining 85% water recovery of WWROC showed only 13–15% flux decline and produced good quality permeate (10–15 µS/cm, 99% ion rejection) at moderate feed temperature of 55 °C. Prevalent calcium carbonate (CaCO3) deposition on the MD membrane occurred in treating WWROC at elevated concentrations. The combination of low salinity and loose CaCO3 adhesion on the membrane did not significantly contribute to DCMD flux decline. Meanwhile, high organic content in WWROC (58–60 mg/L) resulted in a significant membrane hydrophobicity reduction (70% lower water contact angle than virgin membrane) attributed to low molecular weight organic adhesion onto the MD membrane. Granular activated carbon (GAC) pretreatment helped in reducing organic contents of WWROC by 46–50%, and adsorbed a range of hydrophobic and hydrophilic micropollutants. This ensured high quality water production by MD (micropollutants-free) and enhanced its reuse potential. The MD concentrated WWROC was suitable for selective ion precipitation, promising a near zero liquid discharge in WRPs.

  8. Membrane distillation for wastewater reverse osmosis concentrate treatment with water reuse potential

    KAUST Repository

    Naidu, Gayathri; Jeong, Sanghyun; Choi, Youngkwon; Vigneswaran, Saravanamuthu

    2016-01-01

    Membrane distillation (MD) was evaluated as a treatment option of wastewater reverse osmosis concentrate (WWROC) discharged from wastewater reclamation plants (WRPs). A direct contact MD (DCMD), at obtaining 85% water recovery of WWROC showed only 13–15% flux decline and produced good quality permeate (10–15 µS/cm, 99% ion rejection) at moderate feed temperature of 55 °C. Prevalent calcium carbonate (CaCO3) deposition on the MD membrane occurred in treating WWROC at elevated concentrations. The combination of low salinity and loose CaCO3 adhesion on the membrane did not significantly contribute to DCMD flux decline. Meanwhile, high organic content in WWROC (58–60 mg/L) resulted in a significant membrane hydrophobicity reduction (70% lower water contact angle than virgin membrane) attributed to low molecular weight organic adhesion onto the MD membrane. Granular activated carbon (GAC) pretreatment helped in reducing organic contents of WWROC by 46–50%, and adsorbed a range of hydrophobic and hydrophilic micropollutants. This ensured high quality water production by MD (micropollutants-free) and enhanced its reuse potential. The MD concentrated WWROC was suitable for selective ion precipitation, promising a near zero liquid discharge in WRPs.

  9. [Computer modeling the dependences of the membrane potential for polymeric membrane separated non-homogeneous electrolyte solutions on concentration Rayleigh number].

    Science.gov (United States)

    Slezak, Izabella H; Jasik-Slezak, Jolanta; Bilewicz-Wyrozumska, Teresa; Slezak, Andrzej

    2006-01-01

    On the basis of model equation describing the membrane potential delta psi(s) on concentration Rayleigh number (R(C)), mechanical pressure difference (deltaP), concentration polarization coefficient (zeta s) and ratio concentration of solutions separated by membrane (Ch/Cl), the characteristics delta psi(s) = f(Rc)(delta P, zeta s, Ch/Cl) for steady values of zeta s, R(C) and Ch/Cl in single-membrane system were calculated. In this system neutral and isotropic polymeric membrane oriented in horizontal plane, the non-homogeneous binary electrolytic solutions of various concentrations were separated. Nonhomogeneity of solutions is results from creations of the concentration boundary layers on both sides of the membrane. Calculations were made for the case where on a one side of the membrane aqueous solution of NaCl at steady concentration 10(-3) mol x l(-1) (Cl) was placed and on the other aqueous solutions of NaCl at concentrations from 10(-3) mol x l(-1) to 2 x 10(-2) mol x l(-1) (Ch). Their densities were greater than NaCl solution's at 10(-3) mol x l(-1). It was shown that membrane potential depends on hydrodynamic state of a complex concentration boundary layer-membrane-concentration boundary layer, what is controlled by deltaP, Ch/Cl, Rc and Zeta(s).

  10. Maximally asymmetric transbilayer distribution of anionic lipids alters the structure and interaction with lipids of an amyloidogenic protein dimer bound to the membrane surface.

    Science.gov (United States)

    Cheng, Sara Y; Chou, George; Buie, Creighton; Vaughn, Mark W; Compton, Campbell; Cheng, Kwan H

    2016-03-01

    We used molecular dynamics simulations to explore the effects of asymmetric transbilayer distribution of anionic phosphatidylserine (PS) lipids on the structure of a protein on the membrane surface and subsequent protein-lipid interactions. Our simulation systems consisted of an amyloidogenic, beta-sheet rich dimeric protein (D42) absorbed to the phosphatidylcholine (PC) leaflet, or protein-contact PC leaflet, of two membrane systems: a single-component PC bilayer and double PC/PS bilayers. The latter comprised of a stable but asymmetric transbilayer distribution of PS in the presence of counterions, with a 1-component PC leaflet coupled to a 1-component PS leaflet in each bilayer. The maximally asymmetric PC/PS bilayer had a non-zero transmembrane potential (TMP) difference and higher lipid order packing, whereas the symmetric PC bilayer had a zero TMP difference and lower lipid order packing under physiologically relevant conditions. Analysis of the adsorbed protein structures revealed weaker protein binding, more folding in the N-terminal domain, more aggregation of the N- and C-terminal domains and larger tilt angle of D42 on the PC leaflet surface of the PC/PS bilayer versus the PC bilayer. Also, analysis of protein-induced membrane structural disruption revealed more localized bilayer thinning in the PC/PS versus PC bilayer. Although the electric field profile in the non-protein-contact PS leaflet of the PC/PS bilayer differed significantly from that in the non-protein-contact PC leaflet of the PC bilayer, no significant difference in the electric field profile in the protein-contact PC leaflet of either bilayer was evident. We speculate that lipid packing has a larger effect on the surface adsorbed protein structure than the electric field for a maximally asymmetric PC/PS bilayer. Our results support the mechanism that the higher lipid packing in a lipid leaflet promotes stronger protein-protein but weaker protein-lipid interactions for a dimeric protein on

  11. The action of polyene antibiotics on lipid bilayer membranes in the presence of several cations and anions

    NARCIS (Netherlands)

    Zutphen, H. van; Demel, R.A.; Norman, A.W.; Deenen, L.L.M. van

    1971-01-01

    1. 1. Filipin complex, filipin II, filipin III, nystatin, etruscomycin, and pimaricin at concentrations of 10−5 M were able to disrupt bimolecular lipid films containing lecithin and cholesterol in a 1:1 molar ratio. 2. 2. The above antibiotics were not able to disrupt lecithin bilayer

  12. Effect of concentration variation in graphene oxide (GO) membranes for water flux optimization

    Science.gov (United States)

    Kumar, Shani; Garg, Amit; Chowdhuri, Arijit

    2018-05-01

    Graphene oxide, sister material of Graphene has generated tremendous research interest in fields of energy storage, catalyst material, adsorbent material for heavy metals and dyes, green energy production, drug delivery agent, a gas sensing material as well as in membrane based water purification and desalination systems1-3 etc. In this paper, we are reporting the effect of concentration variation in GO membranes on water flux. GO has been synthesized by Hummer's method with related characterizations like XRD, Raman, SEM and FTIR carried out. GO membranes have been developed using pressure assisted filtration assembly (Water Vac-100) over Cellulose Acetate membrane support (47 mm dia. and 0.45 µm pore size), Millipore.

  13. Highly efficient transition metal and nitrogen co-doped carbide-derived carbon electrocatalysts for anion exchange membrane fuel cells

    Science.gov (United States)

    Ratso, Sander; Kruusenberg, Ivar; Käärik, Maike; Kook, Mati; Puust, Laurits; Saar, Rando; Leis, Jaan; Tammeveski, Kaido

    2018-01-01

    The search for an efficient electrocatalyst for oxygen reduction reaction (ORR) to replace platinum in fuel cell cathode materials is one of the hottest topics in electrocatalysis. Among the many non-noble metal catalysts, metal/nitrogen/carbon composites made by pyrolysis of cheap materials are the most promising with control over the porosity and final structure of the catalyst a crucial point. In this work we show a method of producing a highly active ORR catalyst in alkaline media with a controllable porous structure using titanium carbide derived carbon as a base structure and dicyandiamide along with FeCl3 or CoCl2 as the dopants. The resulting transition metal-nitrogen co-doped carbide derived carbon (M/N/CDC) catalyst is highly efficient for ORR electrocatalysis with the activity in 0.1 M KOH approaching that of commercial 46.1 wt.% Pt/C. The catalyst materials are also investigated by scanning electron microscopy, Raman spectroscopy and X-ray photoelectron spectroscopy to characterise the changes in morphology and composition causing the raise in electrochemical activity. MEA performance of M/N/CDC cathode materials in H2/O2 alkaline membrane fuel cell is tested with the highest power density reached being 80 mW cm-2 compared to 90 mW cm-2 for Pt/C.

  14. Morphologies and separation characteristics of polyphenyl sulfone-based solvent resistant nanofiltration membranes: Effect of polymer concentration in casting solution and membrane pretreatment condition

    International Nuclear Information System (INIS)

    Sani, Nur Aimie Abdullah; Lau, Woei Jye; Ismail, Ahmad Fauzi

    2015-01-01

    The performance of polyphenylsulfone (PPSU) solvent resistant nanofiltration (SRNF)-based flat sheet membranes prepared from phase inversion method was investigated by varying the concentration of polymer in the dope solution and condition of membrane pretreatment process. The membrane properties were characterized by SEM, FTIR, AFM and contact angle goniometer, while their performance was evaluated by measuring methanol flux and rejection of different molecular weight of dyes (ranging from 269 to 1,470 g/mol) in methanol. The experimental results showed that the polymer concentration has great impact not only on the final membrane morphology but also its separation characteristics. Increasing polymer concentration from 17 to 25wt% tended to suppress finger-like structure and more pear-like pores were developed, causing methanol flux to decrease. This can be explained by the decrease in molecular weight cut off (MWCO) of the membrane prepared at high polymer concentration. With respect to the effect of membrane pretreatment conditions, the rejection of membrane was negatively affected with longer immersion period in methanol solution prior to filtration experiment. The variation in membrane rejection can be attributed to the rearrangement of the polymer chain, which results in membrane swelling and/or change of membrane surface hydrophilicity

  15. Morphologies and separation characteristics of polyphenyl sulfone-based solvent resistant nanofiltration membranes: Effect of polymer concentration in casting solution and membrane pretreatment condition

    Energy Technology Data Exchange (ETDEWEB)

    Sani, Nur Aimie Abdullah; Lau, Woei Jye; Ismail, Ahmad Fauzi [Universiti Teknologi Malaysia, Skudai (Malaysia)

    2015-04-15

    The performance of polyphenylsulfone (PPSU) solvent resistant nanofiltration (SRNF)-based flat sheet membranes prepared from phase inversion method was investigated by varying the concentration of polymer in the dope solution and condition of membrane pretreatment process. The membrane properties were characterized by SEM, FTIR, AFM and contact angle goniometer, while their performance was evaluated by measuring methanol flux and rejection of different molecular weight of dyes (ranging from 269 to 1,470 g/mol) in methanol. The experimental results showed that the polymer concentration has great impact not only on the final membrane morphology but also its separation characteristics. Increasing polymer concentration from 17 to 25wt% tended to suppress finger-like structure and more pear-like pores were developed, causing methanol flux to decrease. This can be explained by the decrease in molecular weight cut off (MWCO) of the membrane prepared at high polymer concentration. With respect to the effect of membrane pretreatment conditions, the rejection of membrane was negatively affected with longer immersion period in methanol solution prior to filtration experiment. The variation in membrane rejection can be attributed to the rearrangement of the polymer chain, which results in membrane swelling and/or change of membrane surface hydrophilicity.

  16. Insulin and adenosine regulate the phosphatidylcholine concentration in isolated rat adipocyte plasma membranes.

    Science.gov (United States)

    Kiechle, F L; Sykes, E; Artiss, J D

    1995-01-01

    Blockade of adenosine receptors by 3-isobutyl-1-methylxanthine or degradation of endogenous adenosine with adenosine deaminase increased the phosphatidylcholine concentration in isolated rat adipocyte plasma membranes, an effect which was suppressed by the phosphatidylethanolamine methyltransferase inhibitor, S-adenosyl-L-homocysteine, and reversed by the adenosine analogue, N6-(L-phenylisopropyl)-adenosine. For example, the addition of N6-(L-phenylisopropyl)-adenosine to adenosine deaminase pretreated plasma membranes rapidly lowered the concentration of phosphatidylcholine by 171 nmol/mg at 30 seconds compared to control. Insulin-induced stimulation of phospholipid methylation in membranes treated with 3-isobutyl-1-methylxanthine or adenosine deaminase was achieved only after the addition of N6-(L-phenylisopropyl)-adenosine. These results suggest that adenosine receptor occupancy inhibits phospholipid methylation, is required for insulin stimulation of phospholipid methylation, and may perhaps activate a phosphatidylcholine-specific phospholipase C or phospholipase D.

  17. Computational fluid dynamics simulations of flow and concentration polarization in forward osmosis membrane systems

    DEFF Research Database (Denmark)

    Gruber, M.F.; Johnson, C.J.; Tang, C.Y.

    2011-01-01

    is inspired by previously published CFD models for pressure-driven systems and the general analytical theory for flux modeling in asymmetric membranes. Simulations reveal a non-negligible external concentration polarization on the porous support, even when accounting for high cross-flow velocity and slip...

  18. Methods and systems for measuring anions

    KAUST Repository

    Masih, Dilshad; Mohammed, Omar F.; Aly, Shawkat M.; Alarousu, Erkki

    2016-01-01

    Embodiments of the present disclosure provide for methods for detecting the presence and/or concentration of anions in a solution, systems for detecting the presence and/or concentration of anions in a solution, anion sensor systems, and the like.

  19. Methods and systems for measuring anions

    KAUST Repository

    Masih, Dilshad

    2016-08-18

    Embodiments of the present disclosure provide for methods for detecting the presence and/or concentration of anions in a solution, systems for detecting the presence and/or concentration of anions in a solution, anion sensor systems, and the like.

  20. Stability of a Cu0.7Co2.3O4 electrode during the oxygen evolution reaction for alkaline anion-exchange membrane water electrolysis

    Science.gov (United States)

    Kang, Kyoung Eun; Kim, Chi Ho; Lee, Myung Sup; Jung, Chang Wook; Kim, Yang Do; Lee, Jae Ho

    2018-01-01

    The electrode materials for oxygen evolution, especially non-platinum group metal oxides, have attracted increasing attention. Among the spinel-type transition metal oxides, Cu0.7Co2.3O4 powders were evaluated as a potential replacement for expensive dimensionally stabilized anode materials. Cu0.7Co2.3O4 powder for use as an electrode material for oxygen evolution in an alkaline anion-exchange membrane water electrolyzer was prepared using a thermal decomposition method. The Cu0.7Co2.3O4 powders heat-treated at 250 °C exhibited the same X-ray diffraction patterns without any secondary phases as the Co3O4 spinel structure did. The Cu0.7Co2.3O4 powders heat-treated at 250 °C for 30 minutes showed the smallest mean particle size of approximately 376 nm with the powders having a homogeneous shape and size distribution. The fine powders with a relatively homogeneous size distribution showed a higher current density during the oxygen evolution reaction. The lifetime of the Cu0.7Co2.3O4 electrode was relatively long at a low current density, but was quickly shortened due to physical detachment of the Cu0.7Co2.3O4 powders as the current density was increased. This study showed that the efficiency and the stability of Cu0.7Co2.3O4 powders during the oxygen evolution reaction were related directly to the active electrode area.

  1. Effect of free calcium concentration and ionic strength on alginate fouling in cross-flow membrane filtration

    NARCIS (Netherlands)

    Brink, van den P.; Zwijnenburg, A.; Smith, G.; Temmink, B.G.; Loosdrecht, van M.C.

    2009-01-01

    Extracellular polymeric substances (EPS) are generally negatively charged polymers. Membrane fouling in membrane bioreactors (MBRs) by EPS is therefore influenced by the water chemistry of the mixed liquor (calcium concentration, foulant concentration and ionic strength). We used alginate as a model

  2. Selective separation and concentration of antihypertensive peptides from rapeseed protein hydrolysate by electrodialysis with ultrafiltration membranes.

    Science.gov (United States)

    He, Rong; Girgih, Abraham T; Rozoy, Elodie; Bazinet, Laurent; Ju, Xing-Rong; Aluko, Rotimi E

    2016-04-15

    Rapeseed protein isolate was subjected to alcalase digestion to obtain a protein hydrolysate that was separated into peptide fractions using electrodialysis with ultrafiltration membrane (EDUF) technology. The EDUF process (6h duration) led to isolation of three peptide fractions: anionic (recovered in KCl-1 compartment), cationic (recovered in KCl-2 compartment), and those that remained in the feed compartment, which was labeled final rapeseed protein hydrolysate (FRPH). As expected the KCl-1 peptides were enriched in negatively-charged (43.57%) while KCl-2 contained high contents of positively-charged (28.35%) amino acids. All the samples inhibited angiotensin converting enzyme (ACE) and renin activities in dose-dependent manner with original rapeseed protein hydrolysate having the least ACE-inhibitory IC50 value of 0.0932±0.0037 mg/mL while FRPH and KCl-2 had least renin-inhibitory IC50 values of 0.47±0.05 and 0.55±0.06 mg/mL, respectively. Six hours after oral administration (100 mg/kg body weight) to spontaneously hypertensive rats, the FRPH produced the maximum systolic blood pressure reduction of -51 mmHg. Copyright © 2015 Elsevier Ltd. All rights reserved.

  3. Effects of Concentration of Organically Modified Nanoclay on Properties of Sulfonated Poly(vinyl alcohol Nanocomposite Membranes

    Directory of Open Access Journals (Sweden)

    Apiradee Sanglimsuwan

    2011-01-01

    Full Text Available Electrolyte nanocomposite membranes for proton exchange membrane fuel cells and direct methanol fuel cells were prepared by carrying out a sulfonation of poly(vinyl alcohol with sulfosuccinic acid and adding a type of organically modified montmorillonite (layered silicate nanoclay commercially known as Cloisite 93A. The effects of the different concentrations (0, 2, 4, 6, 8 wt. % of the organoclay in the membranes on water uptake, ion exchange capacity (IEC, proton conductivity, and methanol permeability were measured, respectively, via gravimetry, titration, impedance analysis, and gas chromatography techniques. The IEC values remained constant for all concentrations. Water uptakes and proton conductivities of the nanocomposite membranes changed with the clay content in a nonlinear fashion. While all the nanocomposite membranes had lower methanol permeability than Nafion115, the 6% concentration of Cloisite 93A in sulfonated poly(vinyl alcohol membrane displayed the greatest proton conductivity to methanol permeability ratio.

  4. The effect of dietary cation-anion difference concentration and cation source on milk production and feed efficiency in lactating dairy cows.

    Science.gov (United States)

    Iwaniuk, M E; Weidman, A E; Erdman, R A

    2015-03-01

    Feed costs currently account for 55% or more of the total cost of milk production in US dairy herds, and dairy producers are looking for strategies to improve feed efficiency [FE; 3.5% fat-corrected milk (FCM) per dry matter (DM) intake]. Increasing dietary cation-anion difference [DCAD; Na+K-Cl (mEq/kg of DM)] has been shown to increase milk production, FCM, and FE. However, the optimal DCAD concentration for maximal FE has yet to be determined. The objectives of this research were to test the effects of DCAD concentration and cation source on dairy FE. Sixty Holstein dairy cows (20 cows per experiment) were used in three 4×4 Latin square design experiments with 3-wk experimental periods. In experiments 1 and 2, we tested the effect of DCAD concentration: cows were fed a basal diet containing ~250 mEq/kg of DM DCAD that was supplemented with potassium carbonate at 0, 50, 100, and 150 mEq/kg of DM or 0, 125, 250, and 375 mEq/kg of DM in experiments 1 and 2, respectively. In experiment 3, we tested the effect of cation source: sodium sesquicarbonate replaced 0, 33, 67, and 100% of the supplemental potassium carbonate (150 mEq/kg of DM DCAD). The DCAD concentration had no effect on milk production, milk protein concentration, or milk protein yield in experiments 1 and 2. Dry matter intake was not affected by DCAD concentration in experiment 1 or by cation source in experiment 3. However, DMI increased linearly with increasing DCAD in experiment 2. We detected a linear increase in milk fat concentration and yield with increasing DCAD in experiments 1 and 2 and by substituting sodium sesquicarbonate for potassium carbonate in experiment 3. Increased milk fat concentration with increasing DCAD led to increases in 3.5% FCM in experiments 1 and 2. Maximal dairy FE was achieved at a DCAD concentration of 426 mEq/kg of DM in experiments 1 and 2 and by substituting Na for K in experiment 3. The results of these experiments suggest that both DCAD concentration and the cation

  5. Concentrated emulsion pathway to novel composite polymeric membranes and their use in pervaporation

    Energy Technology Data Exchange (ETDEWEB)

    Ruckenstein, E.; Sun, F. [State Univ. of New York, Buffalo, NY (United States). Dept. of Chemical Engineering

    1995-10-01

    Pervaporation is becoming recognized as an energy-efficient alternative to distillation and other separation methods of liquid mixtures, especially in cases in which the traditional separation techniques are not efficient, such as the separation of azeotropic mixtures, close-boiling-point components, isomeric components, and recovery or removal of trace organic substances from aqueous solutions. Novel composite polymeric membranes have been prepared, using concentrated emulsions as precursors, and employed in the pervaporation of various liquid mixtures. In order to improve the stability of the concentrated emulsion, the hydrophilicity and/or the hydrophobicity of the phases involved must be increased by replacing them with their solutions in water and/or in a hydrocarbon, respectively. Another possibility of improving the stability is to increase the viscosity of the phases, by partial polymerization of one or both phases before preparing the concentrated emulsion. The emulsion gel was subsequently transformed into a polymer composite by polymerizing both phases. The dispersed phase should be selected to yield a hydrophobic (hydrophilic) polymer which is compatible with the components selected for separation and incompatible with the other components, while the continuous phase should be selected to yield a hydrophilic (hydrophobic) polymer which is incompatible with all of the components of the mixture, and thus it can ensure the integrity of the membrane. As examples, several composite polymeric membranes were designed, prepared, and employed in the separation by pervaporation of water-ethanol,aromatics-paraffinics, and aromatics-alcohol mixtures.

  6. Geometrically Nonlinear Shell Analysis of Wrinkled Thin-Film Membranes with Stress Concentrations

    Science.gov (United States)

    Tessler, Alexander; Sleight, David W.

    2006-01-01

    Geometrically nonlinear shell finite element analysis has recently been applied to solar-sail membrane problems in order to model the out-of-plane deformations due to structural wrinkling. Whereas certain problems lend themselves to achieving converged nonlinear solutions that compare favorably with experimental observations, solutions to tensioned membranes exhibiting high stress concentrations have been difficult to obtain even with the best nonlinear finite element codes and advanced shell element technology. In this paper, two numerical studies are presented that pave the way to improving the modeling of this class of nonlinear problems. The studies address the issues of mesh refinement and stress-concentration alleviation, and the effects of these modeling strategies on the ability to attain converged nonlinear deformations due to wrinkling. The numerical studies demonstrate that excessive mesh refinement in the regions of stress concentration may be disadvantageous to achieving wrinkled equilibrium states, causing the nonlinear solution to lock in the membrane response mode, while totally discarding the very low-energy bending response that is necessary to cause wrinkling deformation patterns.

  7. Omega-3 PUFA concentration by a novel PVDF nano-composite membrane filled with nano-porous silica particles.

    Science.gov (United States)

    Ghasemian, Samaneh; Sahari, Mohammad Ali; Barzegar, Mohsen; Ahmadi Gavlighi, Hasan

    2017-09-01

    In this study, polyvinylidene fluoride (PVDF) and nano-porous silica particle were used to fabricate an asymmetric nano-composite membrane. Silica particles enhanced the thermal stability of PVDF/SiO 2 membranes; increasing the decomposition temperature from 371°C to 408°C. Cross sectional morphology showed that silica particles were dispersed in polymer matrix uniformly. However, particle agglomeration was found at higher loading of silica (i.e., 20 by weight%). The separation performance of nano-composite membranes was also evaluated using the omega-3 polyunsaturated fatty acids (PUFA) concentration at a temperature and pressure of 30°C and 4bar, respectively. Silica particle increased the omega-3PUFA concentration from 34.8 by weight% in neat PVDF to 53.9 by weight% in PVDF with 15 by weight% of silica. Moreover, PVDF/SiO 2 nano-composite membranes exhibited enhanced anti-fouling property compared to neat PVDF membrane. Fouling mechanism analysis revealed that complete pore blocking was the predominant mechanism occurring in oil filtration. The concentration of omega-3 polyunsaturated fatty acids (PUFA) is important in the oil industries. While the current methods demand high energy consumptions in concentrating the omega-3, membrane separation technology offers noticeable advantages in producing pure omega-3 PUFA. Moreover, concentrating omega-3 via membrane separation produces products in the triacylglycerol form which possess better oxidative stability. In this work, the detailed mechanisms of fouling which limits the performance of membrane separation were investigated. Incorporating silica particles to polymeric membrane resulted in the formation of mixed matrix membrane with improved anti-fouling behaviour compared to the neat polymeric membrane. Hence, the industrial potential of membrane processing to concentrate omega-3 fatty acids is enhanced. Copyright © 2017. Published by Elsevier Ltd.

  8. Mercury Concentration Reduction In Waste Water By Using Liquid Surfactant Membrane Technique

    International Nuclear Information System (INIS)

    Prayitno; Sardjono, Joko

    2000-01-01

    The objective of this research is ti know effectiveness of liquid surfactant membrane in diminishing mercury found in waste water. This process can be regarded as transferring process of solved mercury from the external phase functioning as a moving phase to continue to the membrane internal one. The existence of the convection rotation results in the change of the surface pressure on the whole interface parts, so the solved mercury disperses on every interface part. Because of this rotation, the solved mercury will fulfil every space with particles from dispersion phase in accordance with its volume. Therefore, the change of the surface pressure on the whole interface parts can be kept stable to adsorb mercury. The mercury adsorbed in the internal phase moves to dispersed particles through molecule diffusion process. The liquid surfactant membrane technique in which the membrane phase is realized into emulsion contains os kerosene as solvent, sorbitan monoleat (span-80) 5 % (v/v) as surfactant, threbuthyl phosphate (TBP) 10 % (v/v) as extractant, and solved mercury as the internal phase. All of those things are mixed and stirred with 8000 rpm speed for 20 minutes. After the stability of emulsion is formed, the solved mercury is extracted by applying extraction process. The effective condition required to achieve mercury ion recovery utilizing this technique is obtained through extraction and re-extraction process. This process was conducted in 30 minutes with membrane and mercury in scale 1 : 1 on 100 ppm concentration. The results of the processes was 99,6 % efficiency. This high efficiency shows that the liquid surfactant membrane technique is very effective to reduce waste water contamined by mercury

  9. Radiation-induced lipid peroxidation: influence of oxygen concentration and membrane lipid composition

    International Nuclear Information System (INIS)

    Wolters, H.; Tilburg, C.A.M. van; Konings, A.W.T.

    1987-01-01

    Radiation -induced lipid peroxidation phospholipid liposomes was investigated in terms of its dependence on lipid composition and oxygen concentration. Non-peroxidizable lipid incorporated in the liposomes reduced the rate of peroxidation of the peroxidizable phospholipid acyl chains, possibly by restricting the length of chain reactions. The latter effect is believed to be caused by interference of the non-peroxidizable lipids in the bilayer. At low oxygen concentration lipid peroxidation was reduced. The cause of this limited peroxidation may be a reduced number of radical initiation reactions possibly involving oxygen-derived superoxide radicals. Killing of proliferating mammalian cells, irradiated at oxygen concentrations ranging from 0 to 100%, appeared to be independent of the concentration of peroxidizable phospholipids in the cell membranes. This indicates that lipid peroxidation is not the determining process in radiation-induced reproductive cell death. (author)

  10. Production efficiency of micellar casein concentrate using polymeric spiral-wound microfiltration membranes.

    Science.gov (United States)

    Beckman, S L; Zulewska, J; Newbold, M; Barbano, D M

    2010-10-01

    Most current research has focused on using ceramic microfiltration (MF) membranes for micellar casein concentrate production, but little research has focused on the use of polymeric spiral-wound (SW) MF membranes. A method for the production of a serum protein (SP)-reduced micellar casein concentrate using SW MF was compared with a ceramic MF membrane. Pasteurized (79°C, 18s) skim milk (1,100 kg) was microfiltered at 50°C [about 3 × concentration] using a 0.3-μm polyvinylidene fluoride spiral-wound membrane, bleed-and-feed, 3-stage process, using 2 diafiltration stages, where the retentate was diluted 1:2 with reverse osmosis water. Skim milk, permeate, and retentate were analyzed for SP content, and the reduction of SP from skim milk was determined. Theoretically, 68% of the SP content of skim milk can be removed using a single-stage 3× MF. If 2 subsequent water diafiltration stages are used, an additional 22% and 7% of the SP can be removed, respectively, giving a total SP removal of 97%. Removal of SP greater than 95% has been achieved using a 0.1-μm pore size ceramic uniform transmembrane pressure (UTP) MF membrane after a 3-stage MF with diafiltration process. One stage of MF plus 2 stages of diafiltration of 50°C skim milk using a polyvinylidene fluoride polymeric SW 0.3-μm membrane yielded a total SP reduction of only 70.3% (stages 1, 2, and 3: 38.6, 20.8, and 10.9%, respectively). The SP removal rate for the polymeric SW MF membrane was lower in all 3 stages of processing (stages 1, 2, and 3: 0.05, 0.04, and 0.03 kg/m(2) per hour, respectively) than that of the comparable ceramic UTP MF membrane (stages 1, 2, and 3: 0.30, 0.11, and 0.06 kg/m(2) per hour, respectively), indicating that SW MF is less efficient at removing SP from 50°C skim milk than the ceramic UTP system. To estimate the number of steps required for the SW system to reach 95% SP removal, the third-stage SP removal rate (27.4% of the starting material SP content) was used to

  11. Electrodeformation of multi-bilayer spherical concentric membranes by AC electric fields

    Science.gov (United States)

    Lira-Escobedo, J.; Arauz-Lara, J.; Aranda-Espinoza, H.; Adlerz, K.; Viveros-Mendez, P. X.; Aranda-Espinoza, S.

    2017-09-01

    It is now well established that external stresses alter the behaviour of cells, where such alterations can be as profound as changes in gene expression. A type of stresses of particular interest are those due to alternating-current (AC) electric fields. The effect of AC fields on cells is still not well understood, in particular it is not clear how these fields affect the cell nucleus and other organelles. Here, we propose that one possible mechanism is through the deformation of the membranes. In order to investigate the effect of AC fields on the morphological changes of the cell organelles, we modelled the cell as two concentric bilayer membranes. This model allows us to obtain the deformations induced by the AC field by balancing the elastic energy and the work done by the Maxwell stresses. Morphological phase diagrams are obtained as a function of the frequency and the electrical properties of the media and membranes. We demonstrate that the organelle shapes can be changed without modifying the shape of the external cell membrane and that the organelle deformation transitions can be used to measure, for example, the conductivity of the nucleus.

  12. Concentration gradient along the scala tympani after local application of gentamicin to the round window membrane.

    Science.gov (United States)

    Plontke, Stefan K; Mynatt, Robert; Gill, Ruth M; Borgmann, Stefan; Salt, Alec N

    2007-07-01

    The distribution of gentamicin along the fluid spaces of the cochlea after local applications has never previously been demonstrated. Computer simulations have predicted that significant basal-apical concentration gradients might be expected, and histologic studies indicate that hair cell damage is greater at the base than at the apex after local gentamicin application. In the present study, gradients of gentamicin along the cochlea were measured. A recently developed method of sampling perilymph from the cochlear apex of guinea pigs was used in which the samples represent fluid originating from different regions along the scala tympani. Gentamicin concentration was determined in sequential apical samples that were taken after up to 3 hours of local application to the round window niche. Substantial gradients of gentamicin along the length of the scala tympani were demonstrated and quantified, averaging more than 4,000 times greater concentration at the base compared with the apex at the time of sampling. Peak concentrations and gradients for gentamicin varied considerably between animals, likely resulting from variations in round window membrane permeability and rates of perilymph flow. The large gradients for gentamicin demonstrated here in guinea pigs account for how it is possible to suppress vestibular function in some patients with a local application of gentamicin without damaging auditory function. Variations in round window membrane permeability and in perilymph flow could account for why hearing losses are observed in some patients.

  13. Concentration gradient along scala tympani following the local application of gentamicin to the round window membrane

    Science.gov (United States)

    Plontke, Stefan K.; Mynatt, Robert; Gill, Ruth M.; Borgmann, Stefan; Salt, Alec N.

    2008-01-01

    Objectives The distribution of gentamicin along the fluid spaces of the cochlea following local applications has never previously been demonstrated. Computer simulations have predicted that significant basal-apical concentration gradients might be expected and histological studies indicate that hair cell damage is greater at the base than at the apex following local gentamicin application. In the present study, gradients of gentamicin along the cochlea were measured. Methods A recently-developed method of sampling perilymph from the cochlear apex of guinea pigs was used, in which the samples represent fluid originating from different regions along scala tympani. Gentamicin concentration was determined in sequential apical samples which were taken following up to three hours of local application to the round window niche. Results Substantial gradients of gentamicin along the length of scala tympani were demonstrated and quantified, averaging more than 4000 times greater concentration at the base compared to the apex at the time of sampling. Peak concentrations and gradients for gentamicin varied considerably between animals, likely resulting from variations in round window membrane permeability and rates of perilymph flow. Conclusions The large gradients for gentamicin demonstrated here in guinea pigs account for how it is possible to suppress vestibular function in some patients with a local application of gentamicin without damaging auditory function. Variations in round window membrane permeability and in perilymph flow could account for why hearing losses are observed in some patients. PMID:17603318

  14. Effect of Porosity and Concentration Polarization on Electrolyte Diffusive Transport Parameters through Ceramic Membranes with Similar Nanopore Size

    Directory of Open Access Journals (Sweden)

    Virginia Romero

    2014-08-01

    Full Text Available Diffusive transport through nanoporous alumina membranes (NPAMs produced by the two-step anodization method, with similar pore size but different porosity, is studied by analyzing membrane potential measured with NaCl solutions at different concentrations. Donnan exclusion of co-ions at the solution/membrane interface seem to exert a certain control on the diffusive transport of ions through NPAMs with low porosity, which might be reduced by coating the membrane surface with appropriated materials, as it is the case of SiO2. Our results also show the effect of concentration polarization at the membrane surface on ionic transport numbers (or diffusion coefficients for low-porosity and high electrolyte affinity membranes, which could mask values of those characteristic electrochemical parameters.

  15. Anionic lipids and the cytoskeletal proteins MreB and RodZ define the spatio-temporal distribution and function of membrane stress controller PspA in Escherichia coli.

    Science.gov (United States)

    Jovanovic, Goran; Mehta, Parul; Ying, Liming; Buck, Martin

    2014-11-01

    All cell types must maintain the integrity of their membranes. The conserved bacterial membrane-associated protein PspA is a major effector acting upon extracytoplasmic stress and is implicated in protection of the inner membrane of pathogens, formation of biofilms and multi-drug-resistant persister cells. PspA and its homologues in Gram-positive bacteria and archaea protect the cell envelope whilst also supporting thylakoid biogenesis in cyanobacteria and higher plants. In enterobacteria, PspA is a dual function protein negatively regulating the Psp system in the absence of stress and acting as an effector of membrane integrity upon stress. We show that in Escherichia coli the low-order oligomeric PspA regulatory complex associates with cardiolipin-rich, curved polar inner membrane regions. There, cardiolipin and the flotillin 1 homologue YqiK support the PspBC sensors in transducing a membrane stress signal to the PspA-PspF inhibitory complex. After stress perception, PspA high-order oligomeric effector complexes initially assemble in polar membrane regions. Subsequently, the discrete spatial distribution and dynamics of PspA effector(s) in lateral membrane regions depend on the actin homologue MreB and the peptidoglycan machinery protein RodZ. The consequences of loss of cytoplasmic membrane anionic lipids, MreB, RodZ and/or YqiK suggest that the mode of action of the PspA effector is closely associated with cell envelope organization. © 2014 The Authors.

  16. Critical Filler Concentration in Sulfated Titania-Added Nafion™ Membranes for Fuel Cell Applications

    Directory of Open Access Journals (Sweden)

    Mirko Sgambetterra

    2016-04-01

    Full Text Available In this communication we present a detailed study of Nafion™ composite membranes containing different amounts of nanosized sulfated titania particles, synthesized through an optimized one-step synthesis procedure. Functional membrane properties, such as ionic exchange capacity and water uptake (WU ability will be described and discussed, together with thermal analysis, atomic force microscopy and Raman spectroscopy data. Also electrochemical properties such as proton conductivity and performances in hydrogen fuel cells will be presented. It has been demonstrated that a critical concentration of filler particles can boost the fuel cell performance at low humidification, exhibiting a significant improvement of the maximum power and current density delivered under 30% low-relative humidity (RH and 70 °C with respect to bare Nafion™-based systems.

  17. Delipidation of a whey protein concentrate by electroacidification with bipolar membranes.

    Science.gov (United States)

    Shee, Fabrice Lin Teng; Angers, Paul; Bazinet, Laurent

    2007-05-16

    The separation of residual fats from whey protein concentrates (WPC) results in a better nutritional and functional utilization of this product. Bipolar membrane electroacidification (BMEA) technology allows acidification and demineralization of solutions without any salt addition. The principle of BMEA is based on proton formation from water molecule dissociation at the bipolar membrane interface. The objective of this work was to determine the effect of an electroacidification treatment at pH 4.5 on the precipitation of lipids. WPC electroacidification was carried out with or without preliminary demineralization by conventional electrodialysis. The effect of ionic strength on lipid precipitation rates was also evaluated by dilution of the WPC samples. Lipid precipitation levels of 35-39% were obtained using the electroacidification process without a dilution step, while the combination of BMEA and dilution of the WPC resulted in a decrease in lipid content by six-fold from 0.76 to 0.21%.

  18. Development of membrane technology for production of concentrated fertilizer and clean water

    DEFF Research Database (Denmark)

    Camilleri Rumbau, Maria Salud

    The global increasing livestock production is reflected in a high rate of animal waste production, commonly known as manure or animal slurry. These effluents are rich in nutrients such as nitrogen, phosphorus and potassium. Solid-liquid separation of farm effluents is a common practice...... for obtaining a phosphorus-rich fraction and a liquid fraction rich in nitrogen and potassium. However, the nutrient concentration in the obtained liquid fractions remains unbalanced due to the high water content. Membrane technologies have previously proved to be a suitable technology for separation....... During FO processing of digestate liquid fractions, membranes were able to retain ammonia nitrogen -TAN while using a highly saline wastewater from a tannery beam house. A salt rejection higher than 90% was achieved along the experiments. However, when acidification of the feed digestate liquid fraction...

  19. Dexamethasone concentration gradients along scala tympani after application to the round window membrane.

    Science.gov (United States)

    Plontke, Stefan K; Biegner, Thorsten; Kammerer, Bernd; Delabar, Ursular; Salt, Alec N

    2008-04-01

    Local application of dexamethasone-21-dihydrogen-phosphate (Dex-P) to the round window (RW) membrane of guinea pigs produces a substantial basal-apical concentration gradient in scala tympani (ST) perilymph. In recent years, intratympanically applied glucocorticoids are increasingly being used for the treatment of inner ear disease. Although measurements of intracochlear concentrations after RW application exist, there is limited information on the distribution of these drugs in the inner ear fluids. It has been predicted from computer simulations that substantial concentration gradients will occur after RW application, with lower concentrations expected in apical turns. Concentration gradients of other substances along the cochlea have recently been confirmed using a sequential apical sampling method to obtain perilymph. Dexamethasone-21-dihydrogen-phosphate (10 mg/ml) was administered to the RW membrane of guinea pigs (n = 9) in vivo for 2 to 3 hours. Perilymph was then collected using a protocol in which 10 samples, each of approximately 1 mul, were taken sequentially from the cochlear apex into capillary tubes. Dexamethasone-21-dihydrogen-phosphate concentration of the samples was analyzed by high-performance liquid chromatography. Interpretation of sample data using a finite element model allowed the longitudinal gradients of Dex-P in ST to be quantified. The Dex-P content of the first sample in each experiment (dominated by perilymph from apical regions) was substantially lower than that of the third and fourth sample (dominated by basal turn perilymph). These findings qualitatively demonstrated the existence of a concentration gradient along ST. After detailed analysis of the measured sample concentrations using an established finite element computer model, the mean basal-apical concentration gradient was estimated to be 17,000. Both absolute concentrations of Dex-P in ST and the basal-apical gradients were found to vary substantially. The existence of

  20. Cytosolic nucleotides block and regulate the Arabidopsis vacuolar anion channel AtALMT9.

    Science.gov (United States)

    Zhang, Jingbo; Martinoia, Enrico; De Angeli, Alexis

    2014-09-12

    The aluminum-activated malate transporters (ALMTs) form a membrane protein family exhibiting different physiological roles in plants, varying from conferring tolerance to environmental Al(3+) to the regulation of stomatal movement. The regulation of the anion channels of the ALMT family is largely unknown. Identifying intracellular modulators of the activity of anion channels is fundamental to understanding their physiological functions. In this study we investigated the role of cytosolic nucleotides in regulating the activity of the vacuolar anion channel AtALMT9. We found that cytosolic nucleotides modulate the transport activity of AtALMT9. This modulation was based on a direct block of the pore of the channel at negative membrane potentials (open channel block) by the nucleotide and not by a phosphorylation mechanism. The block by nucleotides of AtALMT9-mediated currents was voltage dependent. The blocking efficiency of intracellular nucleotides increased with the number of phosphate groups and ATP was the most effective cellular blocker. Interestingly, the ATP block induced a marked modification of the current-voltage characteristic of AtALMT9. In addition, increased concentrations of vacuolar anions were able to shift the ATP block threshold to a more negative membrane potential. The block of AtALMT9-mediated anion currents by ATP at negative membrane potentials acts as a gate of the channel and vacuolar anion tune this gating mechanism. Our results suggest that anion transport across the vacuolar membrane in plant cells is controlled by cytosolic nucleotides and the energetic status of the cell. © 2014 by The American Society for Biochemistry and Molecular Biology, Inc.

  1. Cytosolic Nucleotides Block and Regulate the Arabidopsis Vacuolar Anion Channel AtALMT9*

    Science.gov (United States)

    Zhang, Jingbo; Martinoia, Enrico; De Angeli, Alexis

    2014-01-01

    The aluminum-activated malate transporters (ALMTs) form a membrane protein family exhibiting different physiological roles in plants, varying from conferring tolerance to environmental Al3+ to the regulation of stomatal movement. The regulation of the anion channels of the ALMT family is largely unknown. Identifying intracellular modulators of the activity of anion channels is fundamental to understanding their physiological functions. In this study we investigated the role of cytosolic nucleotides in regulating the activity of the vacuolar anion channel AtALMT9. We found that cytosolic nucleotides modulate the transport activity of AtALMT9. This modulation was based on a direct block of the pore of the channel at negative membrane potentials (open channel block) by the nucleotide and not by a phosphorylation mechanism. The block by nucleotides of AtALMT9-mediated currents was voltage dependent. The blocking efficiency of intracellular nucleotides increased with the number of phosphate groups and ATP was the most effective cellular blocker. Interestingly, the ATP block induced a marked modification of the current-voltage characteristic of AtALMT9. In addition, increased concentrations of vacuolar anions were able to shift the ATP block threshold to a more negative membrane potential. The block of AtALMT9-mediated anion currents by ATP at negative membrane potentials acts as a gate of the channel and vacuolar anion tune this gating mechanism. Our results suggest that anion transport across the vacuolar membrane in plant cells is controlled by cytosolic nucleotides and the energetic status of the cell. PMID:25028514

  2. Cholesterol concentrations in lipoprotein fractions separated by anion-exchange-high-performance liquid chromatography in healthy dogs and dogs with hypercholesterolemia.

    Science.gov (United States)

    Oda, Hitomi; Mori, Akihiro; Hirowatari, Yuji; Takoura, Toshie; Manita, Daisuke; Takahashi, Tomoya; Shono, Saori; Onozawa, Eri; Mizutani, Hisashi; Miki, Yohei; Itabashi, Yukiko; Sako, Toshinori

    2017-10-01

    Anion-exchange (AEX)-high-performance liquid chromatography (HPLC) for measurement of cholesterol can be used to separate serum lipoproteins (high-density lipoprotein (HDL); low-density lipoprotein (LDL); intermediate-density lipoprotein (IDL); very-low-density lipoprotein (VLDL)) in humans. However, AEX-HPLC has not been applied in veterinary practice. We had three objectives: (i) the validation of AEX-HPLC methods including the correlation of serum cholesterol concentration in lipoprotein fraction measured by AEX-HPLC and gel permeation-HPLC (GP-HPLC) in healthy dogs and those with hypercholesterolemia was investigated; (ii) the reference intervals of lipoprotein fractions measured by AEX-HPLC from healthy dogs (n=40) was established; (iii) lipoprotein fractions from the serum of healthy dogs (n=12) and dogs with hypercholesterolemia (n=23) were compared. Analytic reproducibility and precision of AEX-HPLC were acceptable. Positive correlation between serum concentrations of total cholesterol (Total-Chol), HDL cholesterol (HDL-Chol), LDL cholesterol (LDL-Chol)+IDL cholesterol (IDL-Chol), and VLDL cholesterol (VLDL-Chol) was noted for AEX-HPLC and GP-HPLC in healthy dogs and dogs with hypercholesterolemia. Reference intervals measured by AEX-HPLC for serum concentrations of Total-Chol, HDL-Chol, and LDL-Chol were determined to be 2.97-9.32, 2.79-6.57, 0.16-3.28mmol/L (2.5-97.5% interval), respectively. Furthermore, there was significant difference in lipoprotein profiles between healthy and dogs with hypercholesterolemia. These results suggest that AEX-HPLC can be used to evaluate lipoprotein profiles in dogs and could be a new useful indicator of hyperlipidemia in dogs. Copyright © 2017 Elsevier Ltd. All rights reserved.

  3. Investigation on degradation mechanism of ion exchange membrane immersed in highly concentrated tritiated water under the Broader Approach Activities

    Energy Technology Data Exchange (ETDEWEB)

    Iwai, Yasunori, E-mail: iwai.yasunori@jaea.go.jp; Sato, Katsumi; Yamanishi, Toshihiko

    2014-10-15

    Highlights: • Endurance of Nafion ion exchange membrane immersed into 1.38 × 10{sup 12} Bq/kg of highly concentrated tritiated water has been demonstrated. • The formation of free hydrophobic free products by reactions between radicals on the membrane and oxygen caused the decrease in ionic conductivity. • From the {sup 19}F NMR spectrum, no distinctive degradation in the membrane structure by interaction with tritium was measured. - Abstract: The ion exchange membrane is a key material for electrolysis cells of the water detritiation system. Durability of ion exchange membrane has been demonstrated under the Broader Approach Activities. Long-term exposure of Nafion{sup ®} ion exchange membrane in 1.38 × 10{sup 12} Bq/kg of tritiated water was conducted at room temperature for up to 2 years. The ionic conductivity of Nafion{sup ®} membrane after immersed in tritiated water was changed. The change in color of membrane from colorless to yellowish was caused by reactions of radicals on the polymer and oxygen molecules in air. Infrared Fourier transform spectrum of a yellowish membrane revealed a small peak for bending vibration of C-H situated at 1437 cm{sup −1}, demonstrating the formation of hydrophobic functional group in the membrane. The hydrophilic network in Nafion{sup ®} membrane was partially obstructed by the hydrophobic free products. This caused the decrease in ionic conductivity. The peak for bending vibration was clearly eliminated in the spectrum of the membrane after treatment by acid for removal of free products. The high-resolution solid state {sup 19}F NMR spectrum of a membrane after immersed in tritiated water was similar to that of a membrane irradiated with gamma-rays. From the {sup 19}F NMR spectrum, no distinctive degradation in the membrane structure by interaction with tritium was measured.

  4. Investigation on degradation mechanism of ion exchange membrane immersed in highly concentrated tritiated water under the Broader Approach Activities

    International Nuclear Information System (INIS)

    Iwai, Yasunori; Sato, Katsumi; Yamanishi, Toshihiko

    2014-01-01

    Highlights: • Endurance of Nafion ion exchange membrane immersed into 1.38 × 10 12 Bq/kg of highly concentrated tritiated water has been demonstrated. • The formation of free hydrophobic free products by reactions between radicals on the membrane and oxygen caused the decrease in ionic conductivity. • From the 19 F NMR spectrum, no distinctive degradation in the membrane structure by interaction with tritium was measured. - Abstract: The ion exchange membrane is a key material for electrolysis cells of the water detritiation system. Durability of ion exchange membrane has been demonstrated under the Broader Approach Activities. Long-term exposure of Nafion ® ion exchange membrane in 1.38 × 10 12 Bq/kg of tritiated water was conducted at room temperature for up to 2 years. The ionic conductivity of Nafion ® membrane after immersed in tritiated water was changed. The change in color of membrane from colorless to yellowish was caused by reactions of radicals on the polymer and oxygen molecules in air. Infrared Fourier transform spectrum of a yellowish membrane revealed a small peak for bending vibration of C-H situated at 1437 cm −1 , demonstrating the formation of hydrophobic functional group in the membrane. The hydrophilic network in Nafion ® membrane was partially obstructed by the hydrophobic free products. This caused the decrease in ionic conductivity. The peak for bending vibration was clearly eliminated in the spectrum of the membrane after treatment by acid for removal of free products. The high-resolution solid state 19 F NMR spectrum of a membrane after immersed in tritiated water was similar to that of a membrane irradiated with gamma-rays. From the 19 F NMR spectrum, no distinctive degradation in the membrane structure by interaction with tritium was measured

  5. The diagnostic value of the lactate concentration in the vaginal fluid for diagnosis of premature rupture of membranes

    Directory of Open Access Journals (Sweden)

    N Nazari

    2013-11-01

    Conclusion: Test of Lactate concentration in vaginal fluid test is a valid, quick and easy with high sensitivity and specificity for the diagnosis of premature rupture of membranes the fetus of pregnant women.

  6. Sensor development for in situ detection of concentration polarization and fouling of reverse osmosis membranes

    Science.gov (United States)

    Detrich, Kahlil T.; Goulbourne, Nakhiah C.

    2009-03-01

    The purpose of this research is to evaluate three polymer electroding techniques in developing a novel in situ sensor for an RO system using the electrical response of a thin film composite sensor. Electrical impedance spectroscopy (EIS) was used to measure the sensor response when exposed to sodium chloride solutions with concentrations from 0.1 M to 0.8 M in both single and double bath configurations. An insulated carbon grease sensor was mechanically stable while a composite Direct Assembly Process (DAP) sensor was fragile upon hydration. Scanning electron microscopy results from an impregnation-reduction technique showed gold nanoparticles were deposited most effectively when presoaked in a potassium hydroxide solution and on an uncoated membrane; surface resistances remained too high for sensor implementation. Through thickness carbon grease sensors showed a transient response to changes in concentration, and no meaningful concentration sensitivity was noted for the time scales over which EIS measurements were taken. Surface carbon grease electrodes attached to the polyamide thin film were not sensitive to concentration. The impedance spectra indicated the carbon grease sensor was unable to detect changes in concentration in double bath experiments when implemented with the polyamide surface exposed to salt solutions. DAP sensors lacked a consistent response to changes in concentration too. A reverse double bath experiment with the polysulfone layer exposed to a constant concentration exhibited a transient impedance response similar to through thickness carbon grease sensors in a single bath at constant concentration. These results suggest that the microporous polysulfone layer is responsible for sensor response to concentration.

  7. Performance and Fouling Study of Asymmetric PVDF Membrane Applied in the Concentration of Organic Fertilizer by Direct Contact Membrane Distillation (DCMD

    Directory of Open Access Journals (Sweden)

    Yanfei Liu

    2018-02-01

    Full Text Available This study proposes using membrane distillation (MD as an alternative to the conventional multi-stage flushing (MSF process to concentrate a semi-product of organic fertilizer. By applying a unique asymmetric polyvinylidene fluoride (PVDF membrane, which was specifically designed for MD applications using a nonsolvent thermally induced phase separation (NTIPS method, the direct contact membrane distillation (DCMD performance was investigated in terms of its sustainability in permeation flux, fouling resistance, and anti-wetting properties. It was found that the permeation flux increased with increasing flow rate, while the top-surface facing feed mode was the preferred orientation to achieve 25% higher flux than the bottom-surface facing feed mode. Compared to the commercial polytetrafluoroethylene (PTFE membrane, the asymmetric PVDF membrane exhibited excellent anti-fouling and sustainable flux, with less than 8% flux decline in a 15 h continuous operation, i.e., flux decreased slightly and was maintained as high as 74 kg·m−2·h−1 at 70 °C. Meanwhile, the lost flux was easily recovered by clean water rinsing. Overall 2.6 times concentration factor was achieved in 15 h MD operation, with 63.4% water being removed from the fertilizer sample. Further concentration could be achieved to reach the desired industrial standard of 5x concentration factor.

  8. Preparation and characterization of polysulfone/zeolite mixed matrix membranes for removal of low-concentration ammonia from aquaculture wastewater.

    Science.gov (United States)

    Moradihamedani, Pourya; Abdullah, Abdul Halim

    2018-01-01

    Removal of low-concentration ammonia (1-10 ppm) from aquaculture wastewater was investigated via polysulfone (PSf)/zeolite mixed matrix membrane. PSf/zeolite mixed matrix membranes with different weight ratios (90/10, 80/20, 70/30 and 60/40 wt.%) were prepared and characterized. Results indicate that PSf/zeolite (80/20) was the most efficient membrane for removal of low-concentration ammonia. The ammonia elimination by PSf/zeolite (80/20) from aqueous solution for 10, 7, 5, 3 and 1 ppm of ammonia was 100%, 99%, 98.8%, 96% and 95% respectively. The recorded results revealed that pure water flux declined in higher loading of zeolite in the membrane matrix due to surface pore blockage caused by zeolite particles. On the other hand, ammonia elimination from water was decreased in higher contents of zeolite because of formation of cavities and macrovoids in the membrane substructure.

  9. FOULING CHARACTERIZATION OF MEMBRANE CONTACTORS USED FOR THE RECOVERY AND CONCENTRATION OF AMMONIA FROM UNDIGESTED PIG SLURRY

    DEFF Research Database (Denmark)

    Zarebska, Agata; Norddahl, Birgir; Christensen, Knud Villy

    2012-01-01

    The main obstacle impeding implementation of membrane contactors for the recovery and concentration of ammonia from swine manure is the phenomena of membrane fouling. Fouling is defined as the accumulation of suspended or dissolved substances on the membrane surface and/or within its pores. Due...... to the different types of fouling which can occur in a membrane system, characterization of fouling is a complex problem. Fouling intensity, morphology and composition of fouling layers has been determined using Scanning Electron Microscopy, X-ray Energy Dispersive Spectrometry and Attenuated Total Reflectance...... Infrared Spectrometry. Based on the analysis of fouled membranes, it is concluded that membrane fouling is dominated by organic fouling in combination with biofouling mainly due to adsorption and deposition of undegraded organic matter. The average fouling layer thickness was estimated to 127.4 μm after...

  10. Application of a macrocyclic compound, bambus[6]uril, in tailor-made liquid membranes for highly selective electromembrane extractions of inorganic anions

    Czech Academy of Sciences Publication Activity Database

    Šlampová, Andrea; Šindelář, V.; Kubáň, Pavel

    2017-01-01

    Roč. 950, JAN (2017), s. 49-56 ISSN 0003-2670 R&D Projects: GA ČR(CZ) GA16-09135S Institutional support: RVO:68081715 Keywords : bambus[6]uril * electromembrane extraction selectivity * inorganic anions Subject RIV: CB - Analytical Chemistry, Separation OBOR OECD: Analytical chemistry Impact factor: 4.950, year: 2016

  11. Well-constructed cellulose acetate membranes for forward osmosis: Minimized internal concentration polarization with an ultra-thin selective layer

    KAUST Repository

    Zhang, Sui

    2010-09-01

    The design and engineering of membrane structure that produces low salt leakage and minimized internal concentration polarization (ICP) in forward osmosis (FO) processes have been explored in this work. The fundamentals of phase inversion of cellulose acetate (CA) regarding the formation of an ultra-thin selective layer at the bottom interface of polymer and casting substrate were investigated by using substrates with different hydrophilicity. An in-depth understanding of membrane structure and pore size distribution has been elucidated with field emission scanning electronic microscopy (FESEM) and positron annihilation spectroscopy (PAS). A double dense-layer structure is formed when glass plate is used as the casting substrate and water as the coagulant. The thickness of the ultra-thin bottom layer resulted from hydrophilic-hydrophilic interaction is identified to be around 95nm, while a fully porous, open-cell structure is formed in the middle support layer due to spinodal decomposition. Consequently, the membrane shows low salt leakage with mitigated ICP in the FO process for seawater desalination. The structural parameter (St) of the membrane is analyzed by modeling water flux using the theory that considers both external concentration polarization (ECP) and ICP, and the St value of the double dense-layer membrane is much smaller than those reported in literatures. Furthermore, the effects of an intermediate immersion into a solvent/water mixed bath prior to complete immersion in water on membrane formation have been studied. The resultant membranes may have a single dense layer with an even lower St value. A comparison of fouling behavior in a simple FO-membrane bioreactor (MBR) system is evaluated for these two types of membranes. The double dense-layer membrane shows a less fouling propensity. This study may help pave the way to improve the membrane design for new-generation FO membranes. © 2010 Elsevier B.V.

  12. Effect of anionic salts in concentrate mixture and magnesium intake on some blood and urine minerals and acid-base balance of dry pregnant cows on grass silage based feeding

    Directory of Open Access Journals (Sweden)

    S. TAURIAINEN

    2008-12-01

    Full Text Available Twenty Friesian cows were randomly assigned to one of four prepartum diets in a 2 x 2 factorially designed experiment to determine the effect of anionic salts contained in a concentrate mixture and magnesium (Mg intake on some blood and urine minerals in cows fed a grass silage based diet. Four diets provided either 16 g or 33 g total dietary Mg/day, and had either a low or high cation-anion difference. Dietary cation-anion balance (DCAB of the diets, calculated as milliequivalents [(Na+ + K+ - (Cl- + S2-], was +31 mEq/kg dry matter (DM in the low DCAB group and +340 mEq/kg DM in the high DCAB group. DCAB was formulated using NH4Cl, (NH42SO4 and MgCl2 as anionic salts. Cows received grass silage (5.2 kg DM, hay (1.0 kg DM and concentrate mixture (1.5 kg DM until calving. Blood and urine samples were collected 4, 3, 2 and 1 week before the expected calving date, at calving, the day after calving and 1 week following calving. Cows fed the low DCAB diet had a lower urinary pH (P

  13. Influence of Irradiance, Flow Rate, Reactor Geometry, and Photopromoter Concentration in Mineralization Kinetics of Methane in Air and in Aqueous Solutions by Photocatalytic Membranes Immobilizing Titanium Dioxide

    Directory of Open Access Journals (Sweden)

    Ignazio Renato Bellobono

    2008-01-01

    Full Text Available Photomineralization of methane in air (10.0–1000 ppm (mass/volume of C at 100% relative humidity (dioxygen as oxygen donor was systematically studied at 318±3 K in an annular laboratory-scale reactor by photocatalytic membranes immobilizing titanium dioxide as a function of substrate concentration, absorbed power per unit length of membrane, reactor geometry, and concentration of a proprietary vanadium alkoxide as photopromoter. Kinetics of both substrate disappearance, to yield intermediates, and total organic carbon (TOC disappearance, to yield carbon dioxide, were followed. At a fixed value of irradiance (0.30 W⋅cm-1, the mineralization experiments in gaseous phase were repeated as a function of flow rate (4–400 m3⋅h−1. Moreover, at a standard flow rate of 300 m3⋅h−1, the ratio between the overall reaction volume and the length of the membrane was varied, substantially by varying the volume of reservoir, from and to which circulation of gaseous stream took place. Photomineralization of methane in aqueous solutions was also studied, in the same annular reactor and in the same conditions, but in a concentration range of 0.8–2.0 ppm of C, and by using stoichiometric hydrogen peroxide as an oxygen donor. A kinetic model was employed, from which, by a set of differential equations, four final optimised parameters, k1 and K1, k2 and K2, were calculated, which is able to fit the whole kinetic profile adequately. The influence of irradiance on k1 and k2, as well as of flow rate on K1 and K2, is rationalized. The influence of reactor geometry on k values is discussed in view of standardization procedures of photocatalytic experiments. Modeling of quantum yields, as a function of substrate concentration and irradiance, as well as of concentration of photopromoter, was carried out very satisfactorily. Kinetics of hydroxyl radicals reacting between themselves, leading to hydrogen peroxide, other than with substrate or

  14. Physicochemical properties and the concentration of anions, major and trace elements in groundwater, treated drinking water and bottled drinking water in Najran area, KSA

    Science.gov (United States)

    Brima, Eid I.

    2017-03-01

    Basic information about major elements in bottled drinking water is provided on product labels. However, more information is needed about trace elements in bottled drinking water and other sources of drinking water to assess its quality and suitability for drinking. This is the first such study to be carried out in Najran city in the Kingdom of Saudi Arabia (KSA). A total of 48 water samples were collected from different sources comprising wells, stations for drinking water treatment and bottled drinking water (purchased from local supermarkets). The concentrations of 24 elements [aluminum (Al), arsenic (As), barium (Ba), calcium (Ca), cadmium (Cd), cobalt (Co), chromium (Cr), cesium (Cs), copper (Cu), iron (Fe), potassium (K), magnesium (Mg), manganese (Mn), molydenum (Mo), sodium (Na), nickel (Ni), lead (Pb), rubidium (Rb), selenium (Se), strontium (Sr), titanium (Ti), vanadium (V), uranium (U) and zinc (Zn)] were determined by inductively coupled plasma-mass spectrometry (ICP-MS). Anions (chlorine (Cl-), fluoride (F-), sulfate (SO4 2-) and nitrate (NO3 -) were determined by ion chromatography (IC). Electrical conductivity (EC), pH, total dissolved salts (TDS) and total hardness (TH) were also measured. All parameters of treated drinking water and bottled drinking water samples did not exceed the World Health Organization (WHO) 2008, US Environmental Protection Agency (USEPA 2009), Gulf Cooperation Council Standardization Organization (GSO) 2008 and Saudi Arabian Standards Organization (SASO) 1984 recommended guidelines. It is noteworthy that groundwater samples were not used for drinking purpose. This study is important to raise public knowledge about drinking water, and to promote public health.

  15. Liquid membrane system for the removal and concentration of transuranic elements

    International Nuclear Information System (INIS)

    Timmins, M.R.; Wysk, S.R.; Smolensky, L.A.; Jiang, D.; Lumetta, G.J.

    1996-01-01

    The goal of this program is to develop an efficient, reliable, and radiation-resistant modified liquid membrane system (MLMS) for the selective removal and concentration of transuranic elements (TRUs) and strontium-90 from dissolved Hanford sludge wastes. The efforts are divided into three categories: (1) demonstration and optimization of the MLMS for the TRUEX and SREX processes using simulant waste solution; (2) development of a radiation-resistant microporous divider and membrane module for testing with actual waste solutions; and (3) demonstration of the MLMS for the TRUEX and SREX processes using actual Hanford waste. Successful completion of these development efforts will yield a compact, versatile, and reliable MLMS for implementation with the TRUEX and SREX processes. The MLMS is simple, stable, more efficient, and easier to control and operate than conventional solvent-extraction processes, such as those employing centrifugal contactors. In addition, the MLMS process offers operational cost savings over the conventional technology, by exhibiting at least a 10% reduction in the consumption of extractant chemicals

  16. Revealing Transient Concentration of CO2 in a Mixed Matrix Membrane by IR Microimaging and Molecular Modeling

    KAUST Repository

    Hwang, Seungtaik

    2018-02-21

    Through IR microimaging the spatially and temporally resolved development of the CO2 concentration in a ZIF-8@6FDA-DAM mixed matrix membrane was visualized during transient adsorption. By recording the evolution of the CO2 concentration, it is observed that the CO2 molecules propagate from the ZIF-8 filler, which acts as a transport

  17. Revealing Transient Concentration of CO2 in a Mixed Matrix Membrane by IR Microimaging and Molecular Modeling

    KAUST Repository

    Hwang, Seungtaik; Semino, Rocio; Seoane, Beatriz; Zahan, Marufa; Chmelik, Christian; Valiullin, Rustem; Bertmer, Marko; Haase, Jü rgen; Kapteijn, Freek; Gascon, Jorge; Maurin, Guillaume; Kä rger, Jö rg

    2018-01-01

    Through IR microimaging the spatially and temporally resolved development of the CO2 concentration in a ZIF-8@6FDA-DAM mixed matrix membrane was visualized during transient adsorption. By recording the evolution of the CO2 concentration, it is observed that the CO2 molecules propagate from the ZIF-8 filler, which acts as a transport

  18. Determination of the free ion concentration of trace metals in soil solution using a soil column Donnan membrane technique

    NARCIS (Netherlands)

    Weng, L.; Temminghoff, E.J.M.; Riemsdijk, van W.H.

    2001-01-01

    Accurate measurement of the free metal ion is difficult, especially for trace metals present in very small concentrations (less than micromolar) in natural systems. The recently developed Donnan membrane technique can measure the concentrations in solution in the presence of inorganic and organic

  19. Hofmeister effect of anions on calcium translocation by sarcoplasmic reticulum Ca2+-ATPase

    Science.gov (United States)

    Tadini-Buoninsegni, Francesco; Moncelli, Maria Rosa; Peruzzi, Niccolò; Ninham, Barry W.; Dei, Luigi; Nostro, Pierandrea Lo

    2015-10-01

    The occurrence of Hofmeister (specific ion) effects in various membrane-related physiological processes is well documented. For example the effect of anions on the transport activity of the ion pump Na+, K+-ATPase has been investigated. Here we report on specific anion effects on the ATP-dependent Ca2+ translocation by the sarcoplasmic reticulum Ca2+-ATPase (SERCA). Current measurements following ATP concentration jumps on SERCA-containing vesicles adsorbed on solid supported membranes were carried out in the presence of different potassium salts. We found that monovalent anions strongly interfere with ATP-induced Ca2+ translocation by SERCA, according to their increasing chaotropicity in the Hofmeister series. On the contrary, a significant increase in Ca2+ translocation was observed in the presence of sulphate. We suggest that the anions can affect the conformational transition between the phosphorylated intermediates E1P and E2P of the SERCA cycle. In particular, the stabilization of the E1P conformation by chaotropic anions seems to be related to their adsorption at the enzyme/water and/or at the membrane/water interface, while the more kosmotropic species affect SERCA conformation and functionality by modifying the hydration layers of the enzyme.

  20. Increase The Sugar Concentration of The Solution Sugar by Reverse Osmotic Membrane

    Science.gov (United States)

    Redjeki, S.; Hapsari, N.; Iriani

    2018-01-01

    Sugar is one of the basic needs of people and food and drink industry. As technology advances and the demand for efficient usage of sugar rises, crystal sugar is seen as less advantageous than liquid sugar. If sugar is always dissolved in water before use, then it will be more efficient and practical for consumers to use sugar in liquid form than in crystal form. Other than that, liquid sugar is also attractive to consumers because it is economical, hygienic, instantly soluble in hot and cold water, fresher and longer-lasting, able to thicken and enrich the texture of foods and drinks, and functions as sweetener, syrup, and flavor enhancer. Liquid sugar is also more beneficial for sugar producers because of simpler production process, cheaper production cost, and similar yield with no extra cost. In sugar production, separation process is found in most of its stages and therefore the use of membrane technology for separating solute and water content has a good potential. In this research, water content reduction of sugar solution was done in order to increase the sugar concentration of the solution. The parameters of this research were 4%, 5%, and 6% starting concentration of sugar solution; 20, 40, and 60 minutes of process time; and 85 and 60 PSI ΔP. The best result was acquired on 4% starting concentration, 60 PSI ΔP, and 60 minutes process time.

  1. Utilization of concentrate after membrane filtration of sugar beet thin juice for ethanol production.

    Science.gov (United States)

    Kawa-Rygielska, Joanna; Pietrzak, Witold; Regiec, Piotr; Stencel, Piotr

    2013-04-01

    The subject of this study was to investigate the feasibility of the concentrate obtained after membrane ultrafiltration of sugar beet thin juice for ethanol production and selection of fermentation conditions (yeast strain and media supplementation). Resulting concentrate was subjected to batch ethanol fermentation using two strains of Saccharomyces cerevisiae (Ethanol Red and Safdistill C-70). The effect of different forms of media supplementation (mineral salts: (NH4)2SO4, K2HPO4, MgCl2; urea+Mg3(PO4)2 and yeast extract) on the fermentation course was also studied. It was stated that sugar beet juice concentrate is suitable for ethanol production yielding, depending on the yeast strain, ca. 85-87 g L(-1) ethanol with ca. 82% practical yield and more than 95% of sugars consumption after 72 h of fermentation. Nutrients enrichment further increased ethanol yield. The best results were obtained for media supplemented with urea+Mg3(PO4)2 yielding 91.16-92.06 g L(-1) ethanol with practical yield ranging 84.78-85.62% and full sugars consumption. Copyright © 2013. Published by Elsevier Ltd.

  2. Alveolar and serum concentrations of imipenem in two lung transplant recipients supported with extracorporeal membrane oxygenation.

    Science.gov (United States)

    Welsch, C; Augustin, P; Allyn, J; Massias, L; Montravers, P; Allou, N

    2015-02-01

    Venovenous extracorporeal membrane oxygenation (ECMO) is increasingly used in patients with respiratory failure who fail conventional treatment. Postoperative pneumonia is the most common infection after lung transplantation (40%). Imipenem is frequently used for empirical treatment of nosocomial pneumonia in the intensive care unit. Nevertheless, few data are available on the impact of ECMO on pharmacokinetics, and no data on imipenem dosing during ECMO. Currently, no guidelines exist for antibiotic dosing during ECMO support. We report the cases of 2 patients supported with venovenous ECMO for refractory acute respiratory distress syndrome following single lung transplantation for pulmonary fibrosis, treated empirically with 1 g of imipenem intravenously every 6 h. Enterobacter cloacae was isolated from the respiratory sample of Patient 1 and Klebsiella pneumoniae was isolated from the respiratory sample of Patient 2. Minimum inhibitory concentrations of the 2 isolated strains were 0.125 and 0.25 mg/L, respectively. Both patients were still alive on day 28. This is the first report, to our knowledge, of imipenem concentrations in lung transplantation patients supported with ECMO. This study confirms high variability in imipenem trough concentrations in patients on ECMO and with preserved renal function. An elevated dosing regimen (4 g/24 h) is more likely to optimize drug exposure, and therapeutic drug monitoring is recommended, where available. Population pharmacokinetic studies are indicated to develop evidence-based dosing guidelines for ECMO patients. © 2015 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  3. Pre-concentration and quantification of uranium from lean feed by stir adsorptive membranes

    International Nuclear Information System (INIS)

    Das, Sadananda; Pandey, A.K.; Manchanda, V.K.; Athawale, A.A.

    2010-01-01

    Uranium recovery from bio-aggressive but lean feed like seawater is a challenging problem as it requires in situ preconcentration of uranium in presence of huge excess of competing ions with fast sorption kinetics. In our laboratory, widely used amidoxime membrane (AO-membrane) was evaluated for uranium sorption under seawater conditions. This study indicated that AO-membrane was inherently slow because of the complexation chemistry involved in transfer of U(VI) from (UO 2 (CO 3 ) 3 ) 4- to AO sites in membrane. In order to search better options, several chemical compositions of membrane were scanned for their efficacy for uranium preconcentration from seawater, and concluded that EGMP-membrane offers several advantages over AO-membrane. In this paper, the comparison of EGMP-membrane with AO-membrane for uranium sorption under seawater conditions has been reviewed. (author)

  4. Full scale plant with membrane based concentration of blackcurrant juice on the basis of laboratory and pilot scale tests

    DEFF Research Database (Denmark)

    Fjerbæk Søtoft, Lene; Christensen, K. V.; Andresen, R.

    2012-01-01

    A conceptual process design with the use of integrated membrane processes is prepared for blackcurrant juice concentrate (BCJC) production to replace traditional multiple step evaporators and aroma recovery. The combination of membrane processes includes aroma recovery with vacuum membrane distil...... is 0.40 (sic)/kg BCJC, which is lower than the price of a traditional operation by about 43%. Therefore, the economical potential of the process is very promising and could supersede conventional evaporators. (C) 2012 Elsevier B.V. All rights reserved....

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

    International Nuclear Information System (INIS)

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

    2011-01-01

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

  6. Impacts of NF concentrate recirculation on membrane performance in an integrated MBR and NF membrane process for wastewater treatment

    NARCIS (Netherlands)

    Kappel, C.; Kemperman, A.J.B.; Temmink, B.G.; Zwijnenburg, A.; Rijnaarts, H.; Nijmeijer, K.

    2014-01-01

    As water shortages are increasing, the need for sustainable water treatment and the reuse of water is essential. Water reuse from wastewater can be accomplished in a membrane bioreactor (MBR) in the secondary activated sludge stage of a wastewater treatment plant. To remove viruses, dissolved

  7. Freely dissolved concentrations of anionic surfactants in seawater solutions: optimization of the non-depletive solid-phase microextraction method and application to linear alkylbenzene sulfonates.

    NARCIS (Netherlands)

    Rico Rico, A.; Droge, S.T.J.; Widmer, D.; Hermens, J.L.M.

    2009-01-01

    A solid-phase microextraction method (SPME) has been optimized for the analysis of freely dissolved anionic surfactants, namely linear alkylbenzene sulfonates (LAS), in seawater. An effect of the thermal conditioning treatment on the polyacrylate fiber coating was demonstrated for both uptake

  8. Oxygen diffusion-concentration in phospholipidic model membranes. An ESR-saturation study

    International Nuclear Information System (INIS)

    Vachon, A.; Lecomte, C.; Berleur, F.

    1986-04-01

    Fully hydrated liposomes of dipalmitoyl-phosphatidylcholine were labelled with 5 (or 7, 10, 12, 16)-doxyl stearic acid at pH 6 and 8, and studied by the continuous wave ESR-saturation technique. The ESR spectral magnitude depends on the hyperfrequency power P and on both T 1 and T 2 relaxation times. Saturation, i.e. the non linearity of the spectral magnitude plotted versus √P can be quantified by a P1/2 parameter (power at which the signal is half as great as it would be without saturation). If we assume T 2 weakly modified by spin exchange between paramagnetic spin probe and oxygen in triplet state, P1/2 is inversely proportional to T 1 , and becomes a sensitive parameter to appreciate the oxygen transport (oxygen diffusion-concentration product) inside the bilayers. According to the DPPC bilayer phase transition diagrams, P1/2 (oxygen diffusion-concentration) is related to the thermodynamic state of the membrane. This technique provides further informations on a particular property of a radioprotective agent, cysteamine, which seems to inhibit spin-triplet exchange and hence maximizes T 1 (minimizes P1/2). Since radioprotective agents are known to act by scavenging radiation-induced free radicals and by inhibiting oxygen-dependent free radical processes, such a result may contribute to elucidate radioprotecting mechanisms

  9. Production of Concentrated Pickering Emulsions with Narrow Size Distributions Using Stirred Cell Membrane Emulsification.

    Science.gov (United States)

    Manga, Mohamed S; York, David W

    2017-09-12

    Stirred cell membrane emulsification (SCME) has been employed to prepare concentrated Pickering oil in water emulsions solely stabilized by fumed silica nanoparticles. The optimal conditions under which highly stable and low-polydispersity concentrated emulsions using the SCME approach are highlighted. Optimization of the oil flux rates and the paddle stirrer speeds are critical to achieving control over the droplet size and size distribution. Investigating the influence of oil volume fraction highlights the criticality of the initial particle loading in the continuous phase on the final droplet size and polydispersity. At a particle loading of 4 wt %, both the droplet size and polydispersity increase with increasing of the oil volume fraction above 50%. As more interfacial area is produced, the number of particles available in the continuous phase diminishes, and coincidently a reduction in the kinetics of particle adsorption to the interface resulting in larger polydisperse droplets occurs. Increasing the particle loading to 10 wt % leads to significant improvements in both size and polydispersity with oil volume fractions as high as 70% produced with coefficient of variation values as low as ∼30% compared to ∼75% using conventional homogenization techniques.

  10. Technical Performance and Economic Evaluation of Evaporative and Membrane-Based Concentration for Biomass-Derived Sugars

    International Nuclear Information System (INIS)

    Sievers, David A.; Stickel, Jonathan J.; Grundl, Nicholas J.; Tao, Ling

    2017-01-01

    Several conversion pathways of lignocellulosic biomass to advanced biofuels require or benefit from using concentrated sugar syrups of 600 g/L or greater. And while concentration may seem straightforward, thermal sugar degradation and energy efficiency remain major concerns. This study evaluated the trade-offs in product recovery, energy consumption, and economics between evaporative and membrane-based concentration methods. The degradation kinetics of xylose and glucose were characterized and applied to an evaporator process simulation. Though significant sugar loss was predicted for certain scenarios due to the Maillard reaction, industrially common falling-film plate evaporators offer short residence times (<5 min) and are expected to limit sugar losses. Membrane concentration experiments characterized flux and sugar rejection, but diminished flux occurred at >100 g/L. A second step using evaporation is necessary to achieve target concentrations. Techno-economic process model simulations evaluated the overall economics of concentrating a 35 g/L sugar stream to 600 g/L in a full-scale biorefinery. A two-step approach of preconcentrating using membranes and finishing with an evaporator consumed less energy than evaporation alone but was more expensive because of high capital expenses of the membrane units.

  11. Study on concentrating treatment test of simulated radioactive wastewater containing boron by reverse osmosis membrane in PWR NPP

    International Nuclear Information System (INIS)

    Ye Xinnan; Jiang Baihua; Fan Wenwen; Zhang Zhiyin; Yang Cangsheng

    2015-01-01

    The reverse osmosis membrane equipment in PWR NPP was employed to investigate the application of pilot scale system in the radioactive wastewater treatment at the full recirculation operation. The removal performance of the equipment for the boron and the radioactivity nuclide were studied, respectively. The experimental results show that the removal efficiency of the aromatic polyamide composite reverse osmosis membrane for boron is over 83.3% and the concentration of boron in concentrate is over 10000 mg/L. The experimental results also show that the removal efficiency of two nuclides including cobalt and cesium is over 97.9%. (authors)

  12. Power Generation from Concentration Gradient by Reverse Electrodialysis in Dense Silica Membranes for Microfluidic and Nanofluidic Systems

    Directory of Open Access Journals (Sweden)

    Sang Woo Lee

    2016-01-01

    Full Text Available In this study, we investigate power generation by reverse electrodialysis in a dense silica membrane that is between two NaCl solutions with various combinations of concentrations. Each silica membrane is fabricated by depositing a silica layer on a porous alumina substrate via chemical vapor deposition. The measured potential-current (V-I characteristics of the silica membrane are used to obtain the transference number, diffusion potential, and electrical resistance. We develop empirical correlations for the transference number and the area-specific resistance, and present the results of power generation by reverse electrodialysis using the fabricated silica membranes. The highest measured power density is 0.98 mW/m2. In addition, we develop a contour map of the power density as a function of NaCl concentrations on the basis of the empirical correlations. The contour map shows that a power output density of 1.2 mW/m2 is achievable with the use of silica membranes and is sufficient to drive nanofluidic and microfluidic systems. The dense silica membrane has the potential for use in micro power generators in nanofluidic and microfluidic systems.

  13. Nanofiltration and Tight Ultrafiltration Membranes for Natural Organic Matter Removal-Contribution of Fouling and Concentration Polarization to Filtration Resistance.

    Science.gov (United States)

    Winter, Joerg; Barbeau, Benoit; Bérubé, Pierre

    2017-07-02

    Nanofiltration (NF) and tight ultrafiltration (tight UF) membranes are a viable treatment option for high quality drinking water production from sources with high concentrations of contaminants. To date, there is limited knowledge regarding the contribution of concentration polarization (CP) and fouling to the increase in resistance during filtration of natural organic matter (NOM) with NF and tight UF. Filtration tests were conducted with NF and tight UF membranes with molecular weight cut offs (MWCOs) of 300, 2000 and 8000 Da, and model raw waters containing different constituents of NOM. When filtering model raw waters containing high concentrations of polysaccharides (i.e., higher molecular weight NOM), the increase in resistance was dominated by fouling. When filtering model raw waters containing humic substances (i.e., lower molecular weight NOM), the increase in filtration resistance was dominated by CP. The results indicate that low MWCO membranes are better suited for NOM removal, because most of the NOM in surface waters consist mainly of humic substances, which were only effectively rejected by the lower MWCO membranes. However, when humic substances are effectively rejected, CP can become extensive, leading to a significant increase in filtration resistance by the formation of a cake/gel layer at the membrane surface. For this reason, cross-flow operation, which reduces CP, is recommended.

  14. Nanofiltration and Tight Ultrafiltration Membranes for Natural Organic Matter Removal—Contribution of Fouling and Concentration Polarization to Filtration Resistance

    Directory of Open Access Journals (Sweden)

    Joerg Winter

    2017-07-01

    Full Text Available Nanofiltration (NF and tight ultrafiltration (tight UF membranes are a viable treatment option for high quality drinking water production from sources with high concentrations of contaminants. To date, there is limited knowledge regarding the contribution of concentration polarization (CP and fouling to the increase in resistance during filtration of natural organic matter (NOM with NF and tight UF. Filtration tests were conducted with NF and tight UF membranes with molecular weight cut offs (MWCOs of 300, 2000 and 8000 Da, and model raw waters containing different constituents of NOM. When filtering model raw waters containing high concentrations of polysaccharides (i.e., higher molecular weight NOM, the increase in resistance was dominated by fouling. When filtering model raw waters containing humic substances (i.e., lower molecular weight NOM, the increase in filtration resistance was dominated by CP. The results indicate that low MWCO membranes are better suited for NOM removal, because most of the NOM in surface waters consist mainly of humic substances, which were only effectively rejected by the lower MWCO membranes. However, when humic substances are effectively rejected, CP can become extensive, leading to a significant increase in filtration resistance by the formation of a cake/gel layer at the membrane surface. For this reason, cross-flow operation, which reduces CP, is recommended.

  15. Demonstration on endurance of ion exchange membrane immersed in high-concentration tritiated water under the Broader Approach Activities

    Energy Technology Data Exchange (ETDEWEB)

    Iwai, Yasunori, E-mail: iwai.yasunori@jaea.go.jp; Sato, Katsumi; Kawamura, Yoshinori; Yamanishi, Toshihiko

    2013-10-15

    Highlights: • Endurance of Nafion ion exchange membrane immersed in 1.38 × 10{sup 12} Bq/kg of highly concentrated tritiated water was demonstrated. • Degradation of Nafion backbone structure by tritium beta was similar to that by gamma rays and electron beams at an equivalent dose. • Degradation directly by radiation was dominant at room temperature compared with that by reactions with radicals produced from water radiolysis. -- Abstract: The Nafion{sup ®} ion exchange membrane is a key material for electrolysis cells of the water detritiation system. Endurance of Nafion ion exchange membrane immersed in 1.38 × 10{sup 12} Bq/kg of highly concentrated tritiated water has been demonstrated at room temperature for up to 2 years under the Broader Approach Activities. The curves of percent elongation at break vs. dose and tensile strength vs. dose for the Nafion membranes immersed in tritiated water were well consistent with those for Nafion membranes irradiated to an equivalent dose with gamma rays and electron beams. This shows that the degradation of Nafion backbone structure by tritium beta is similar to that by gamma rays and electron beams. The results of ferric Fenton test indicated that the degradation directly by radiation was dominant at room temperature compared with that by reactions with radicals produced from water radiolysis. The curve of ion exchange capacity vs. dose for the Nafion membranes immersed in tritiated water was also well consistent with that for Nafion membranes irradiated to an equivalent dose with gamma rays and electron beams. These results showed irradiation tests with gamma rays and electron beams were alternative for predicting degradation of ion exchange membrane by tritium beta.

  16. Anion channels: master switches of stress responses.

    Science.gov (United States)

    Roelfsema, M Rob G; Hedrich, Rainer; Geiger, Dietmar

    2012-04-01

    During stress, plant cells activate anion channels and trigger the release of anions across the plasma membrane. Recently, two new gene families have been identified that encode major groups of anion channels. The SLAC/SLAH channels are characterized by slow voltage-dependent activation (S-type), whereas ALMT genes encode rapid-activating channels (R-type). Both S- and R-type channels are stimulated in guard cells by the stress hormone ABA, which leads to stomatal closure. Besides their role in ABA-dependent stomatal movement, anion channels are also activated by biotic stress factors such as microbe-associated molecular patterns (MAMPs). Given that anion channels occur throughout the plant kingdom, they are likely to serve a general function as master switches of stress responses. Copyright © 2012 Elsevier Ltd. All rights reserved.

  17. Semipermeable membrane devices concentrate mixed function oxygenase inducers from oil sands and refinery wastewaters

    International Nuclear Information System (INIS)

    Parrott, J.L.; Hewitt, L.M.

    2002-01-01

    The health of fish in the Athabasca River was examined to determine the effects of both natural and anthropogenic oil sands exposure on liver mixed function oxygenase (MFO) enzymes. Semipermeable membrane devices (SPMD) were used to concentrate bioavailable compounds that may result in MFO induction. The SPMDs were used for a period of 2 weeks in the Steepbank River as well as in oil refinery wastewater and intake ponds. They were then tested to see if they induced ethoxyresorufin-O-deethylase (EROD) activity in hepatoma cells, a cell line derived from a liver cancer of a small fish. SPMDs from the wastewater pond contained potent EROD inducers in fish liver cells. SPMDs from the Athabasca River exhibited some EROD inducers, but they were 1/100 as potent as those of the refinery wastewater. The characteristics of MFO inducers from refinery wastewater were different from natural inducers from the oil sands in the Athabasca and Steepbank Rivers. For instance, log Kow was less than 5 for refinery wastewater, but it was greater than 5 for Athabasca River wastewater and from natural oil sands exposure. In the case of the Steepbank River, the pattern of MFO induction was similar to the MFO induction seen in wild fish.The highest MFO inducers were found to be in the area of the mine, suggesting and anthropogenic pollution source. The less potent inducers were in the area of the natural and undisturbed oil sands. Very few inducers were found outside of the oil sands formation

  18. Fs-laser-induced Ca2+ concentration change during membrane perforation for cell transfection.

    Science.gov (United States)

    Baumgart, J; Bintig, W; Ngezahayo, A; Lubatschowski, H; Heisterkamp, A

    2010-02-01

    Fs-laser based opto-perforation is a gentle method for gene transfer into sensitive cells such as stem cells or primary cells. The high selectivity and the low damage to the cell lead to a high efficiency of transfection. However, there are side effects which induce stress to the cell due to the exchange of intra- and extracellular media as well as the disintegration of the structure of biomolecules resulting from the laser exposure. Moreover, the mechanisms of the optical transfection are still unclear. In this paper, we present our study on calcium (Ca(2+)) homeostasis during cell surgery, especially during laser induced membrane perforation. We show that the manipulation of cells can induce an increase in the cytosolic Ca(2+) concentration. This increase was not observed if the manipulation of the cells was performed in absence of the extracellular calcium indicating the importance of the Ca(2+) uptake. We found, that the uptake of extracellular Ca(2+) strongly depends on the repetition rate and the irradiation time of the laser pulses. The exposure for several seconds to kHz pulses even induces Ca(2+) induced Ca(2+) release. Dependent on the location of perforation, probably in the vicinity of an intracellular Ca(2+) stock, an instantaneous intracellular Ca(2+) release can be induced. Since Ca(2+) could be involved in negative side effect by cell surgery, we propose an application of the optoperforation technique in nominal Ca(2+)-free external solution.

  19. Successive membrane separation processes simplify concentration of lipases produced by Aspergillus niger by solid-state fermentation.

    Science.gov (United States)

    Reinehr, Christian Oliveira; Treichel, Helen; Tres, Marcus Vinicius; Steffens, Juliana; Brião, Vandré Barbosa; Colla, Luciane Maria

    2017-06-01

    In this study, we developed a simplified method for producing, separating, and concentrating lipases derived from solid-state fermentation of agro-industrial residues by filamentous fungi. First, we used Aspergillus niger to produce lipases with hydrolytic activity. We analyzed the separation and concentration of enzymes using membrane separation processes. The sequential use of microfiltration and ultrafiltration processes made it possible to obtain concentrates with enzymatic activities much higher than those in the initial extract. The permeate flux was higher than 60 L/m 2 h during microfiltration using 20- and 0.45-µm membranes and during ultrafiltration using 100- and 50-kDa membranes, where fouling was reversible during the filtration steps, thereby indicating that the fouling may be removed by cleaning processes. These results demonstrate the feasibility of lipase production using A. niger by solid-state fermentation of agro-industrial residues, followed by successive tangential filtration with membranes, which simplify the separation and concentration steps that are typically required in downstream processes.

  20. Alteration in peripheral blood concentration of certain pro-inflammatory cytokines in cows developing retention of fetal membranes.

    Science.gov (United States)

    Boro, Prasanta; Kumaresan, A; Pathak, Rupal; Patbandha, T K; Kumari, Susavi; Yadav, Asha; Manimaran, A; Baithalu, R K; Attupuram, Nitin M; Mohanty, T K

    2015-06-01

    Retention of fetal membranes (RFM) adversely affects the production and reproduction potential of the affected cows leading to huge economic loss. Physiological separation of fetal membranes is reported to be an inflammatory process. The present study compared the concentrations of certain pro inflammatory cytokines [Interleukin 1β (IL-1), Interleukin 6 (IL-6), Interleukin 8 (IL-8) and Tumor necrosis factor α (TNF-α) between the cows that developed RFM (n=10) and the cows that expelled fetal membranes normally (n=10) to find out if they could serve as a predictive tool for RFM. Blood samples were collected from the cows from 30 days before expected parturition through day -21, day -14, day -7, day -5, day -3, day -1, on the day of parturition (day 0), day 1 postpartum and the pro-inflammatory cytokines were estimated in blood plasma by ELISA method. The IL-1β concentration was significantly lower (Pmembranes normally from 3 days before calving till the day of calving. The plasma concentrations of IL-6 and IL-8 were also lower (Pmembranes normally. It may be inferred that the concentrations of IL-1, IL-6, IL-8 and TNF-α around parturition were altered in cows developing RFM compared to those expelled fetal membranes normally. Copyright © 2015. Published by Elsevier B.V.

  1. Isolation and partial characterization of gypsy moth BTR-270, an anionic brush border membrane glycoconjugate that binds Bacillus thuringiensis Cry1A toxins with high affinity

    Science.gov (United States)

    Algimantas P. Valaitis; Jeremy L. Jenkins; Mi Kyong Lee; Donald H. Dean; Karen J. Garner

    2001-01-01

    BTR-270, a gypsy moth (Lymantria dispar) brush border membrane molecule that binds Bacillus thuringiensis (Bt) Cry1A toxins with high affinity, was purified by preparative gel electrophoresis. Rabbit antibodies specific for the Bt toxin-binding molecule were raised. Attempts to label BTR-270 by protein-directed techniques were...

  2. Multilayer network representation of membrane potential and cytosolic calcium concentration dynamics in beta cells

    International Nuclear Information System (INIS)

    Gosak, Marko; Dolenšek, Jurij; Markovič, Rene; Slak Rupnik, Marjan; Marhl, Marko; Stožer, Andraž

    2015-01-01

    Highlights: • Physiological processes within and among pancreatic beta cells are very complex. • We analyze the simultaneous recordings of membrane potential and calcium dynamics. • We represent the interaction patterns among beta cells as a multilayer network. • The nature of the intracellular dynamics is found to rely on the network structure. - Abstract: Modern theory of networks has been recognized as a very successful methodological concept for the description and analysis of complex systems. However, some complex systems are more complex than others. For instance, several real-life systems are constituted by interdependent subsystems and their elements are subjected to different types of interactions that can also change with time. Recently, the multilayer network formalism has been proposed as a general theoretical framework for the description and analysis of such multi-dimensional complex systems and is acquiring more and more prominence in terms of a new research direction. In the present study, we use this methodology for the description of functional connectivity patterns and signal propagation between pancreatic beta cells in an islet of Langerhans at the levels of membrane potential (MP) and cytosolic calcium concentration ([Ca"2"+]_c) dynamics to study the extent of overlap in the two networks and to clarify whether time lags between the two signals in individual cells are in any way dependent on the role these cells play in the functional networks. The two corresponding network layers are constructed on the basis of signal directions and pairwise correlations, whereas the interlayer connections represent the time lag between both measured signals. Our results confirm our previous finding that both MP and [Ca"2"+]_c change spread across an islet in the form of a depolarization and a [Ca"2"+]_c wave, respectively. Both types of waves follow nearly the same path and the networks in both layers have a similar but not entirely the same structure

  3. Agarose gel electrophoresis of cerebrospinal fluid proteins of dogs after sample concentration using a membrane microconcentrator technique.

    Science.gov (United States)

    Gama, Fernanda Gomes Velasque; Santana, Aureo Evangelista; Filho, Eugênio de Campos; Nogueira, Cláudia Aparecida da Silva

    2007-03-01

    Cerebrospinal fluid (CSF) is produced in the cerebral ventricles through ultrafiltration of plasma and active transport mechanisms. Evaluation of proteins in CSF may provide important information about the production of immunoglobulins within the central nervous system as well as possible disturbances in the blood-brain barrier. The objective of this study was to measure the concentration and fractions of protein in CSF samples using a membrane microconcentrator technique followed by electrophoresis, and to compare the protein fractions obtained with those in serum. CSF samples from 3 healthy dogs and 3 dogs with canine distemper virus infection were concentrated using a membrane microconcentrator having a 0.5 to 30,000 d nominal molecular weight limit (Ultrafree, Millipore, Billerica, MA, USA). Protein concentration was determined before and after concentration. Agarose gel electrophoresis was done on concentrated CSF samples, serum, and serial dilutions of one of the CSF samples. Electrophoretic bands were clearly identified in densitometer tracings in CSF samples with protein concentrations as low as 1.3 g/dL. The higher CSF protein concentration in dogs with distemper was mainly the result of increased albumin concentration. The microconcentrating method used in this study enables characterization of the main protein fractions in CSF by routine electrophoresis and may be useful for interpreting the underlying cause of changes in CSF protein concentrations.

  4. Investigation of patterned and non-patterned poly(2,6-dimethyl 1,4-phenylene) oxide based anion exchange membranes for enhanced desalination and power generation in a microbial desalination cell.

    Science.gov (United States)

    Moruno, Francisco Lopez; Rubio, Juan E; Santoro, Carlo; Atanassov, Plamen; Cerrato, José M; Arges, Christopher G

    2018-01-01

    Quaternary ammonium poly(2,6-dimethyl 1,4-phenylene oxide) (QAPPO) anion exchange membranes (AEMs) with topographically patterned surfaces were assessed in a microbial desalination cell (MDC) system. The MDC results with these QAPPO AEMs were benchmarked against a commercially available AEM. The MDC with the non-patterned QAPPO AEM (Q1) displayed the best desalination rate (a reduction of salinity by 53 ± 2.7%) and power generation (189 ± 5 mW m - 2 ) when compared against the commercially available AEM and the patterned AEMs. The enhanced performance with the Q1 AEM was attributed to its higher ionic conductivity and smaller thickness leading to a reduced area specific resistance. It is important to note that Real Pacific Ocean seawater and activated sludge were used into the desalination chamber and anode chamber respectively for the MDC - which mimicked realistic conditions. Although the non-patterned QAPPO AEM displayed better performance over the patterned QAPPO AEMs, it was observed that the anodic overpotential was smaller when the MDCs featured QAPPO AEMs with larger lateral feature sizes. The results from this study have important implications for the continuous improvements necessary for developing cheaper and better performing membranes in order to optimize the MDC.

  5. IMPROVING OF ANION EXCHANGERES REGENERATION

    Directory of Open Access Journals (Sweden)

    Muzher M. Ibrahim

    2013-05-01

    Full Text Available Inthis study, Different basis [NaOH and KOH] of variable concentration are usedto reactivate Anion exchangers employing different schemes .The Laboratoryresults showed large improvement in efficiency of these exchangers ( i.eoperating time was increased from 12 to 42 hours .The results of this work showed that the environmentalload (waste water can be reduced greatly when using the proposed regenerationscheme .

  6. Concentration of phenolic acids and flavonoids in aronia melanocarpa (choke berry) juice by osmotic membrane distillation

    DEFF Research Database (Denmark)

    Fjerbæk Søtoft, Lene; Christensen, Knud Villy; Horn, Vibeke G

    2009-01-01

    melanocarpa is among the red fruits with the highest content of antioxidants [2] and has gained must interest due to the content of phenolic acids, procyanidins and polyphenolic compounds as anthocyanins [3]. In this study, osmotic membrane distillation (OMD) has been tested for the concentration of not only...... sugars, but in particular potentially bioactive components such as phenolic acids and flavonoids. OMD is carried out on 37 kg aronia juice at 30°C and the juice is concentrated from 12 wt% to 74 wt% dry matter. The juice is filtered to remove kernels, peel residues etc before concentration by OMD...

  7. Dermcidin, an anionic antimicrobial peptide: influence of lipid charge, pH and Zn2+ on its interaction with a biomimetic membrane.

    Science.gov (United States)

    Becucci, Lucia; Valensin, Daniela; Innocenti, Massimo; Guidelli, Rolando

    2014-01-28

    The mechanism of membrane permeabilization by dermcidin (DCD-1L), an antimicrobial peptide present in human sweat, was investigated at a mercury-supported monolayer of dioleoylphosphatidylcholine (DOPC) or dioleoylphosphatidylserine (DOPS) and at a mercury-supported tethered bilayer lipid membrane (tBLM) consisting of a thiolipid (DPTL) with a DOPC or DOPS monolayer self-assembled on top of it. In an unbuffered solution of pH 5.4, DCD-1L is almost neutral and permeabilizes a DPTL/DOPS tBLM at transmembrane potentials, ϕtrans, which are physiological. In a pH 7 buffer solution DCD-1L bears two negative charges and has no effect on a DPTL/DOPC tBLM, whereas it permeabilizes a DPTL/DOPS tBLM only outside the physiological ϕtrans range; however, the presence of zinc ion induces DCD-1L to permeabilize the DPTL/DOPS tBLM at physiological ϕtrans values. The effect of zinc ions suggests a DCD-1L conformation with its positive N-terminus embedded in the lipid bilayer and the negative C terminus floating on the membrane surface. This conformation can be stabilized by a zinc ion bridge between the His(38) residue of the C terminus and the carboxyl group of DOPS. Chronocoulometric potential jumps from ϕtrans ≅ +160 mV to sufficiently negative values yield charge transients exhibiting a sigmoidal shape preceded by a relatively long "foot". This behavior is indicative of ion-channel formation characterized by disruption of DCD-1L clusters adsorbed on top of the lipid bilayer, incorporation of the resulting monomers and their aggregation into hydrophilic pores by a mechanism of nucleation and growth.

  8. Influence of phosphorus precipitation on permeability and soluble microbial product concentration in a membrane bioreactor

    Czech Academy of Sciences Publication Activity Database

    Gómez, M.; Dvořák, L.; Růžičková, I.; Wanner, J.; Holba, Marek; Sýkorová, E.

    2013-01-01

    Roč. 129, Feb 2013 (2013), s. 164-169 ISSN 0960-8524 Institutional support: RVO:67985939 Keywords : membrane bioreactor * coagulant adition * soluble microbial products Subject RIV: EF - Botanics Impact factor: 5.039, year: 2013

  9. in Situ Formation of a Biocatalytic Alginate Membrane by Enhanced Concentration Polarization

    DEFF Research Database (Denmark)

    Marpani, Fauziah; Luo, Jianquan; Mateiu, Ramona Valentina

    2015-01-01

    A thin alginate layer induced on the surface of a commercial polysulfone membrane was used as a matrix for noncovalent immobilization of enzymes. Despite the expected decrease of flux across the membrane resulting from the coating, the initial hypothesis was that such a system should allow high...... immobilized enzyme loadings, which would benefit from the decreased flux in terms of increased enzyme/substrate contact time. The study was performed in a sequential fashion: first, the most suitable types of alginate able to induce a very thin, sustainable gel layer by pressure-driven membrane filtration...... were selected and evaluated. Then, an efficient method to make the gel layer adhere to the surface of the membrane was developed. Finally, and after confirming that the enzyme loading could remarkably be enhanced by using this method, several strategies to increase the permeate flux were evaluated...

  10. Development of composite membranes of PVA-TEOS doped KOH for alkaline membrane fuel cell

    International Nuclear Information System (INIS)

    Haryadi,; Sugianto, D.; Ristopan, E.

    2015-01-01

    Anion exchange membranes (AEMs) play an important role in separating fuel and oxygen (or air) in the Alkaline Membrane Fuel Cells. Preparation of hybrid organic inorganic materials of Polyvinylalcohol (PVA) - Tetraethylorthosilicate (TEOS) composite membrane doped KOH for direct alcohol alkaline fuel cell application has been investigated. The sol-gel method has been used to prepare the composite membrane of PVA-TEOS through crosslinking step and catalyzed by concentrated of hydrochloric acid. The gel solution was cast on the membrane plastic plate to obtain membrane sheets. The dry membranes were then doped by immersing in various concentrations of KOH solutions for about 4 hours. Investigations of the cross-linking process and the presence of hydroxyl group were conducted by FTIR as shown for frequency at about 1600 cm −1 and 3300 cm −1 respectively. The degree of swelling in ethanol decreased as the KOH concentration for membrane soaking process increased. The ion exchange capacity (IEC) of the membrane was 0.25meq/g. This composite membranes display significant ionic conductivity of 3.23 x 10 −2 S/cm in deionized water at room temperature. In addition, the morphology observation by scanning electron microscope (SEM) of the membrane indicates that soaking process of membrane in KOH increased thermal resistant

  11. Development of composite membranes of PVA-TEOS doped KOH for alkaline membrane fuel cell

    Energy Technology Data Exchange (ETDEWEB)

    Haryadi,, E-mail: haryadi@polban.ac.id; Sugianto, D.; Ristopan, E. [Department of Chemical Engineering, Politeknik Negeri Bandung Jl. Gegerkalong Hilir, Ds. Ciwaruga, Bandung West Java (Indonesia)

    2015-12-29

    Anion exchange membranes (AEMs) play an important role in separating fuel and oxygen (or air) in the Alkaline Membrane Fuel Cells. Preparation of hybrid organic inorganic materials of Polyvinylalcohol (PVA) - Tetraethylorthosilicate (TEOS) composite membrane doped KOH for direct alcohol alkaline fuel cell application has been investigated. The sol-gel method has been used to prepare the composite membrane of PVA-TEOS through crosslinking step and catalyzed by concentrated of hydrochloric acid. The gel solution was cast on the membrane plastic plate to obtain membrane sheets. The dry membranes were then doped by immersing in various concentrations of KOH solutions for about 4 hours. Investigations of the cross-linking process and the presence of hydroxyl group were conducted by FTIR as shown for frequency at about 1600 cm{sup −1} and 3300 cm{sup −1} respectively. The degree of swelling in ethanol decreased as the KOH concentration for membrane soaking process increased. The ion exchange capacity (IEC) of the membrane was 0.25meq/g. This composite membranes display significant ionic conductivity of 3.23 x 10{sup −2} S/cm in deionized water at room temperature. In addition, the morphology observation by scanning electron microscope (SEM) of the membrane indicates that soaking process of membrane in KOH increased thermal resistant.

  12. Development of composite membranes of PVA-TEOS doped KOH for alkaline membrane fuel cell

    Science.gov (United States)

    Haryadi, Sugianto, D.; Ristopan, E.

    2015-12-01

    Anion exchange membranes (AEMs) play an important role in separating fuel and oxygen (or air) in the Alkaline Membrane Fuel Cells. Preparation of hybrid organic inorganic materials of Polyvinylalcohol (PVA) - Tetraethylorthosilicate (TEOS) composite membrane doped KOH for direct alcohol alkaline fuel cell application has been investigated. The sol-gel method has been used to prepare the composite membrane of PVA-TEOS through crosslinking step and catalyzed by concentrated of hydrochloric acid. The gel solution was cast on the membrane plastic plate to obtain membrane sheets. The dry membranes were then doped by immersing in various concentrations of KOH solutions for about 4 hours. Investigations of the cross-linking process and the presence of hydroxyl group were conducted by FTIR as shown for frequency at about 1600 cm-1 and 3300 cm-1 respectively. The degree of swelling in ethanol decreased as the KOH concentration for membrane soaking process increased. The ion exchange capacity (IEC) of the membrane was 0.25meq/g. This composite membranes display significant ionic conductivity of 3.23 x 10-2 S/cm in deionized water at room temperature. In addition, the morphology observation by scanning electron microscope (SEM) of the membrane indicates that soaking process of membrane in KOH increased thermal resistant.

  13. Determining time-weighted average concentrations of nitrate and ammonium in freshwaters using DGT with ion exchange membrane-based binding layers

    DEFF Research Database (Denmark)

    Huang, Jianyin; Bennett, William W.; Welsh, David T.

    2016-01-01

    Commercially-available AMI-7001 anion exchange and CMI-7000 cation exchange membranes were utilised as binding layers for DGT measurements of NO3-N and NH4-N in freshwaters. These ion exchange membranes are easier to prepare and handle than DGT binding layers consisting of hydrogels cast with ion...... exchange resins. The membranes showed good uptake and elution efficiencies for both NO3-N and NH4-N. The membrane-based DGTs are suitable for pH 3.5-8.5 and ionic strength ranges (0.0001-0.014 and 0.0003-0.012 mol L−1 as NaCl for the AMI-7001 and CMI-7000 membrane, respectively) typical of most natural...... freshwaters. The binding membranes had high intrinsic binding capacities for NO3-N and NH4-N of 911 ± 88 μg and 3512 ± 51 μg, respectively. Interferences from the major competing ions for membrane-based DGTs are similar to DGTs employing resin-based binding layers but with slightly different selectivity...

  14. Zero-Gap Alkaline Water Electrolysis Using Ion-Solvating Polymer Electrolyte Membranes at Reduced KOH Concentrations

    DEFF Research Database (Denmark)

    Kraglund, Mikkel Rykær; Aili, David; Jankova Atanasova, Katja

    2016-01-01

    Membranes based on poly(2,2'-(m-phenylene)-5,5-bibenzimidazole) (m-PBI) can dissolve large amounts of aqueous KOH to give electrolyte systems with ion conductivity in a practically useful range. The conductivity of the membrane strongly depends on the concentration of the aqueous KOH phase......, reaching about 10-1 S cm-1 or higher in 15-25 wt% KOH. Herein, m-PBI membranes are systematically characterized with respect to performance and short-term stability as electrolyte in a zero-gap alkaline water electrolyzer at different KOH concentrations. Using plain uncatalyzed nickel foam electrodes......, the cell based on m-PBI outperforms the cell based on the commercially available state-of-the-art diaphragm and reaches a current density of 1500 mA cm-2 at 2.4 V in 20 wt% KOH at 80°C. The cell performance remained stable during two days of operation, though post analysis of the membrane using size...

  15. INFLUENCE AT DIFFERENT OPERATION CONDITIONS ON THE ACEROLA JUICE CONCENTRATION BY REVERSE OSMOSIS, USING SPIRAL MEMBRANE OF COMPOSITE FILM

    Directory of Open Access Journals (Sweden)

    E. R.S. GOMES

    2009-03-01

    Full Text Available

    The concentration of acerola juice, involves removal of water with the objective of reducing packing, storage and transport costs. The reverse osmosis (RO is a process of increasing interest in food industry and among the advantages they stand out: the low consumption of energy and the minimum thermal damages is caused to the products. The objective of this work was to evaluate the influence of different operation conditions in relation to the permeate flux, in the concentration process of the acerola juice by RO. All the RO experiments were carried out with retentate recycling. The concentration by RO, were carried on the transmembrane pressures of 20, 30 and 40 bar and at 23ºC and 40ºC, being used a membrane of composite film in spiral module (99% NaCl rejection. The acerola pulp was defrosted and treated with Citrozym Ultra L enzyme (100 ppm, 45ºC ,1 hour, then it was ultrafiltrated at 3 bar at the same temperature, in 0.1 µm ceramic membrane, and so it was concentrated by RO. It was verified that the pressure and the temperature influenced the concentration and the permeate flux obtained in the RO process. The flux decreased along the processing, once the feeding becomes more concentrate, increasing the viscosity, osmotic pressure and retained sugar. KEYWORDS: Acerola juice concentration; reverse osmosis; membrane of composite film.

  16. Process for removing sulfate anions from waste water

    Science.gov (United States)

    Nilsen, David N.; Galvan, Gloria J.; Hundley, Gary L.; Wright, John B.

    1997-01-01

    A liquid emulsion membrane process for removing sulfate anions from waste water is disclosed. The liquid emulsion membrane process includes the steps of: (a) providing a liquid emulsion formed from an aqueous strip solution and an organic phase that contains an extractant capable of removing sulfate anions from waste water; (b) dispersing the liquid emulsion in globule form into a quantity of waste water containing sulfate anions to allow the organic phase in each globule of the emulsion to extract and absorb sulfate anions from the waste water and (c) separating the emulsion including its organic phase and absorbed sulfate anions from the waste water to provide waste water containing substantially no sulfate anions.

  17. Extracellular Determinants of Anion Discrimination of the Cl−/H+ Antiporter Protein CLC-5*

    Science.gov (United States)

    De Stefano, Silvia; Pusch, Michael; Zifarelli, Giovanni

    2011-01-01

    Mammalian CLC proteins comprise both Cl− channels and Cl−/H+ antiporters that carry out fundamental physiological tasks by transporting Cl− across plasma membrane and intracellular compartments. The NO3− over Cl− preference of a plant CLC transporter has been pinpointed to a conserved serine residue located at Scen and it is generally assumed that the other two binding sites of CLCs, Sext and Sin, do not substantially contribute to anion selectivity. Here we show for the Cl−/H+ antiporter CLC-5 that the conserved and extracellularly exposed Lys210 residue is critical to determine the anion specificity for transport activity. In particular, mutations that neutralize or invert the charge at this position reverse the NO3− over Cl− preference of WT CLC-5 at a concentration of 100 mm, but do not modify the coupling stoichiometry with H+. The importance of the electrical charge is shown by chemical modification of K210C with positively charged cysteine-reactive compounds that reintroduce the WT preference for Cl−. At saturating extracellular anion concentrations, neutralization of Lys210 is of little impact on the anion preference, suggesting an important role of Lys210 on the association rate of extracellular anions to Sext. PMID:21921031

  18. Extracellular determinants of anion discrimination of the Cl-/H+ antiporter protein CLC-5.

    Science.gov (United States)

    De Stefano, Silvia; Pusch, Michael; Zifarelli, Giovanni

    2011-12-23

    Mammalian CLC proteins comprise both Cl- channels and Cl-/H+ antiporters that carry out fundamental physiological tasks by transporting Cl- across plasma membrane and intracellular compartments. The NO3- over Cl- preference of a plant CLC transporter has been pinpointed to a conserved serine residue located at Scen and it is generally assumed that the other two binding sites of CLCs, Sext and Sin, do not substantially contribute to anion selectivity. Here we show for the Cl-/H+ antiporter CLC-5 that the conserved and extracellularly exposed Lys210 residue is critical to determine the anion specificity for transport activity. In particular, mutations that neutralize or invert the charge at this position reverse the NO3- over Cl- preference of WT CLC-5 at a concentration of 100 mm, but do not modify the coupling stoichiometry with H+. The importance of the electrical charge is shown by chemical modification of K210C with positively charged cysteine-reactive compounds that reintroduce the WT preference for Cl-. At saturating extracellular anion concentrations, neutralization of Lys210 is of little impact on the anion preference, suggesting an important role of Lys210 on the association rate of extracellular anions to Sext.

  19. Removal of transmissible spongiform encephalopathy prion from large volumes of cell culture media supplemented with fetal bovine serum by using hollow fiber anion-exchange membrane chromatography.

    Science.gov (United States)

    Chou, Ming Li; Bailey, Andy; Avory, Tiffany; Tanimoto, Junji; Burnouf, Thierry

    2015-01-01

    Cases of variant Creutzfeldt-Jakob disease in people who had consumed contaminated meat products from cattle with bovine spongiform encephalopathy emphasize the need for measures aimed at preventing the transmission of the pathogenic prion protein (PrPSc) from materials derived from cattle. Highly stringent scrutiny is required for fetal bovine serum (FBS), a growth-medium supplement used in the production of parenteral vaccines and therapeutic recombinant proteins and in the ex vivo expansion of stem cells for transplantation. One such approach is the implementation of manufacturing steps dedicated to removing PrPSc from materials containing FBS. We evaluated the use of the QyuSpeed D (QSD) adsorbent hollow-fiber anion-exchange chromatographic column (Asahi Kasei Medical, Tokyo, Japan) for the removal of PrPSc from cell culture media supplemented with FBS. We first established that QSD filtration had no adverse effect on the chemical composition of various types of culture media supplemented with 10% FBS or the growth and viability characteristics of human embryonic kidney (HEK293) cells, baby hamster kidney (BHK-21) cells, African green monkey kidney (Vero) cells, and Chinese hamster ovary (CHO-k1) cells propagated in the various culture-medium filtrates. We used a 0.6-mL QSD column for removing PrPSc from up to 1000 mL of Dulbecco's modified Eagle's medium containing 10% FBS previously spiked with the 263K strain of hamster-adapted scrapie. The Western blot analysis, validated alongside an infectivity assay, revealed that the level of PrPSc in the initial 200mL flow-through was reduced by 2.5 to > 3 log10, compared with that of the starting material. These results indicate that QSD filtration removes PrPSc from cell culture media containing 10% FBS, and demonstrate the ease with which QSD filtration can be implemented in at industrial-scale to improve the safety of vaccines, therapeutic recombinant proteins, and ex vivo expanded stem cells produced using growth

  20. Formation of cubic phases from large unilamellar vesicles of dioleoylphosphatidylglycerol/monoolein membranes induced by low concentrations of Ca2+.

    Science.gov (United States)

    Awad, Tarek S; Okamoto, Yoshihide; Masum, Shah Md; Yamazaki, Masahito

    2005-12-06

    We developed a new method for the transformation of large unilamellar vesicles (LUVs) into the cubic phase. We found that the addition of low concentrations of Ca(2+) to suspensions of multilamellar vesicles (MLVs) of membranes of monoolein (MO) and dioleoylphosphatidylglycerol (DOPG) mixtures (DOPG/MO) changed their L(alpha) phase to the cubic phases. For instance, the addition of 15-25 mM Ca(2+) to 30%-DOPG/70%-MO-MLVs induced the Q(229) phase, whereas the addition of > or =28 mM Ca(2+) induced the Q(224) phase. LUVs of DOPG/MO membranes containing > or =25 mol % DOPG were prepared easily. Low concentrations of Ca(2+) transformed these LUVs in excess buffer into the Q(224) or the Q(229) phase, depending on the Ca(2+) concentration. For example, 15 and 50 mM Ca(2+) induced the Q(224) and Q(229) phase in the 30%-DOPG/70%-MO-LUVs at 25 degrees C, respectively. This finding is the first demonstration of transformation of LUVs of lipid membranes into the cubic phase under excess water condition.

  1. Anions in Cometary Comae

    Science.gov (United States)

    Charnley, Steven B.

    2011-01-01

    The presence of negative ions (anions) in cometary comae is known from Giotto mass spectrometry of IP/Halley. The anions 0-, OH-, C-, CH- and CN- have been detected, as well as unidentified anions with masses 22-65 and 85-110 amu (Chaizy et al. 1991). Organic molecular anions are known to have a significant impact on the charge balance of interstellar clouds and circumstellar envelopes and have been shown to act as catalysts for the gas-phase synthesis of larger hydrocarbon molecules in the ISM, but their importance in cometary comae has not yet been explored. We present details of the first attempt to model the chemistry of anions in cometary comae. Based on the combined chemical and hydro dynamical model of Rodgers & Charnley (2002), we investigate the role of large carbon-chain anions in cometary coma chemistry. We calculate the effects of these anions on coma thermodynamics, charge balance and examine their impact on molecule formation.

  2. Development of real-time measurement of methanol-concentration in polymer electrolyte membrane using a local NMR sensor

    International Nuclear Information System (INIS)

    Ogawa, Kuniyasu; Ito, Kohei; Haishi, Tomoyuki

    2007-01-01

    A real-time sensor to measure methanol concentration in polymer electrolyte membrane (PEM) was developed for reducing methanol cross-over in Direct Methanol Fuel Cell (DMFC). The principle of the methanol sensor is based on the chemical shift of CH and OH species under high magnetic field. The sensor consists of a planar surface coil of 1.3 mm outside diameter. NMR signal from PEM being exposed to CH3OH solvent was measured using NMR sensor. Time-dependence changes of methanol concentration in PEM were obtained from analyzing spectrum of NMR signal. (author)

  3. Simulations of simple Bovine and Homo sapiens outer cortex ocular lens membrane models with a majority concentration of cholesterol.

    Science.gov (United States)

    Adams, Mark; Wang, Eric; Zhuang, Xiaohong; Klauda, Jeffery B

    2017-11-21

    The lipid composition of bovine and human ocular lens membranes has been probed, and a variety of lipids have been found including phosphatidylcholine (PC), phosphatidylethanolamine (PE), sphingomyelin (SM), and cholesterol (CHOL) with cholesterol being present in particularly high concentrations. In this study, we use the all-atom CHARMM36 force field to simulate binary, ternary, and quaternary mixtures as models of the ocular lens. High concentration of cholesterol, in combination with different and varying diversity of phospholipids (PL) and sphingolipids (SL), affect the structure of the ocular lens lipid bilayer. The following analyses were done for each simulation: surface area per lipid, component surface area per lipid, deuterium order parameters (S CD ), electron density profiles (EDP), membrane thickness, hydrogen bonding, radial distribution functions, clustering, and sterol tilt angle distribution. The S CD show significant bilayer alignment and packing in cholesterol-rich bilayers. The EDP show the transition from liquid crystalline to liquid ordered with the addition of cholesterol. Hydrogen bonds in our systems show the tendency for intramolecular interactions between cholesterol and fully saturated lipid tails for less complex bilayers. But with an increased number of components in the bilayer, the acyl chain of the lipids becomes a less important characteristic, and the headgroup of the lipid becomes more significant. Overall, cholesterol is the driving force of membrane structure of the ocular lens membrane where interactions between cholesterol, PL, and SL determine structure and function of the biomembrane. The goal of this work is to develop a baseline for further study of more physiologically realistic ocular lens lipid membranes. This article is part of a Special Issue entitled: Emergence of Complex Behavior in Biomembranes edited by Marjorie Longo. Copyright © 2017 Elsevier B.V. All rights reserved.

  4. An empirical study into the effect of long term storage (−36±2 °C) of electron-beamed ETFE on the properties of radiation-grafted alkaline anion-exchange membranes

    International Nuclear Information System (INIS)

    Kizewski, Jamie Peter; Mudri, Nurul H.; Varcoe, John R.

    2013-01-01

    The application of alkaline anion-exchange membranes (AAEM) in solid alkaline fuel cells is growing in prominence mainly due to enhanced tolerance to carbon dioxide, compared to alkaline fuel cells containing aqueous electrolytes, and the potential for using non precious metal catalysts. Radiation grafting is a common methodology for the production of functional polymers and membranes. This statistical study examines the synthesis of radiation grafted AAEMs that are formed from electron beam irradiated poly(ethylene-co-tetrafluoroethylene), EB-ETFE. It is shown that EB-ETFE can be cold stored for at least 16 months and still be used to produce ionically conductive AAEMs. The limitations of routine measurements of properties, such as dimensional increases, ion-exchange capacity, water uptakes and ionic conductivities, are also highlighted. - Highlights: • EB-ETFE films can be used to synthesise viable AAEMs even after storage at −36±2 °C for 16 months. • The AAEMs exhibited ion-exchange capacities in the range 1.0–1.8 mmol g −1 and ionic conductivities (through plane, fully hydrated) in the range 20–40 mS cm −1 at room temperature. • The ionic conductivities of the AAEMs are insensitive to the EB-ETFE storage time (up to the 16 months of this study). • The previously reported bubble formation phenomenon (within the AAEMs) is a major interference in the determination of swelling and water uptake properties. This interference appears more prominent at longer EB-ETFE cold storage times. • Water uptakes are too high for optimal utilisation in fuel cells and AAEMs with both improved ionic conductivities and lower swelling are required

  5. Adsorption of anionic surfactant on porous and nonporous polyethylene terephthalate films

    International Nuclear Information System (INIS)

    Yamauchi, Yu.; Apel, P.Yu.

    2016-01-01

    We study the adsorption of anionic surfactant, sodium dodecyl diphenyloxide disulfonate (SDDD) on three types of polyethylene terephthalate (PET) substrates from aqueous solutions of SDDD of different concentrations. Neutral electrolyte (KCl) was added to the solutions to vary the ionic strength. Three types of substrates were used: 1) original PET film; 2) etched nonporous film, obtained from pristine film by chemical etching and bearing negative charge on the surface; 3) etched porous membranes, fabricated from pristine film by ion irradiation and subsequent chemical etching. The membranes have negative charge on the flat surface and on the inner pore walls. The comparison shows that the negative charge on the flat surface has weak effect on adsorption of the anionic surfactant, and the SDDD adsorption on the inner walls of pores is much weaker than on flat surface, even if the pore radius is significantly larger than the Debye length. This «exclusion» effect strongly depends on ionic strength of solution. [ru

  6. A novel IrNi@PdIr/C core-shell electrocatalyst with enhanced activity and durability for the hydrogen oxidation reaction in alkaline anion exchange membrane fuel cells.

    Science.gov (United States)

    Qin, Bowen; Yu, Hongmei; Jia, Jia; Jun, Chi; Gao, Xueqiang; Yao, Dewei; Sun, Xinye; Song, Wei; Yi, Baolian; Shao, Zhigang

    2018-03-08

    Herein, a novel non-platinum core-shell catalyst, namely, IrNi@PdIr/C was prepared via a galvanic replacement reaction; it exhibits enhanced hydrogen oxidation activity and excellent stability under alkaline conditions. Electrochemical experiments demonstrated that the mass and specific activities at 50 mV of IrNi@PdIr/C are 2.1 and 2.2 times that of commercial Pt/C in 0.1 M KOH at 298 K, respectively. Moreover, accelerated degradation tests have shown that the electrochemically active surface area (ECSA) of IrNi@PdIr/C reduces by only 5.1%, which is almost 4 times less than that of commercial Pt/C and the mass activity at 50 mV of IrNi@PdIr/C after 2000 potential cycles is still 1.8 times higher than that of aged Pt/C. XRD and XPS analysis suggest that the enhanced HOR activity is attributed to the weakening of the hydrogen binding to the PdIr overlayers induced by the IrNi core. The better stability to potential cycling can be associated with the PdIr shell, which inhibits oxide formation. These results suggest that IrNi@PdIr/C is a promising non-platinum anode catalyst for alkaline anion exchange membrane fuel cells.

  7. Assessment of Blend PVDF Membranes, and the Effect of Polymer Concentration and Blend Composition.

    Science.gov (United States)

    Ali, Imtiaz; Bamaga, Omar A; Gzara, Lassaad; Bassyouni, M; Abdel-Aziz, M H; Soliman, M F; Drioli, Enrico; Albeirutty, Mohammed

    2018-03-05

    In this work, PVDF homopolymer was blended with PVDF-co-HFP copolymer and studied in terms of morphology, porosity, pore size, hydrophobicity, permeability, and mechanical properties. Different solvents, namely N-Methyl-2 pyrrolidone (NMP), Tetrahydrofuran (THF), and Dimethylformamide (DMF) solvents, were used to fabricate blended PVDF flat sheet membranes without the introduction of any pore forming agent, through a non-solvent induced phase separation (NIPS) technique. Furthermore, the performance of the fabricated membranes was investigated for pressure and thermal driven applications. The porosity of the membranes was slightly increased with the increase in the overall content of PVDF and by the inclusion of PVDF copolymer. Total PVDF content, copolymer content, and mixed-solvent have a positive effect on mechanical properties. The addition of copolymer increased the hydrophobicity when the total PVDF content was 20%. At 25% and with the inclusion of mixed-solvent, the hydrophobicity was adversely affected. The permeability of the membranes increased with the increase in the overall content of PVDF. Mixed-solvents significantly improved permeability.

  8. FBAR syndapin 1 recognizes and stabilizes highly curved tubular membranes in a concentration dependent manner

    DEFF Research Database (Denmark)

    Ramesh, Pradeep; Baroji, Younes F.; Seyyed Reihani, Seyyed Nader

    2013-01-01

    Syndapin 1 FBAR, a member of the Bin-amphiphysin-Rvs (BAR) domain protein family, is known to induce membrane curvature and is an essential component in biological processes like endocytosis and formation and growth of neurites. We quantify the curvature sensing of FBAR on reconstituted porcine b...

  9. Impregnated membranes for direct methanol fuel cells at high methanol concentrations

    NARCIS (Netherlands)

    Yildirim, M.H.; Schwarz, Alexander; Stamatialis, Dimitrios; Wessling, Matthias

    2009-01-01

    Sulfonated poly(phthalazinone ether ketone) (SPPEK) impregnated Solupor® microporous film (SPPEK–PE) and pure SPPEK membranes with two different ion-exchange capacities (IECs) were prepared and characterized for use in DMFC applications. Swelling, proton conductivity, diffusion and DMFC experiments

  10. Assessment of Blend PVDF Membranes, and the Effect of Polymer Concentration and Blend Composition

    Directory of Open Access Journals (Sweden)

    Imtiaz Ali

    2018-03-01

    Full Text Available In this work, PVDF homopolymer was blended with PVDF-co-HFP copolymer and studied in terms of morphology, porosity, pore size, hydrophobicity, permeability, and mechanical properties. Different solvents, namely N-Methyl-2 pyrrolidone (NMP, Tetrahydrofuran (THF, and Dimethylformamide (DMF solvents, were used to fabricate blended PVDF flat sheet membranes without the introduction of any pore forming agent, through a non-solvent induced phase separation (NIPS technique. Furthermore, the performance of the fabricated membranes was investigated for pressure and thermal driven applications. The porosity of the membranes was slightly increased with the increase in the overall content of PVDF and by the inclusion of PVDF copolymer. Total PVDF content, copolymer content, and mixed-solvent have a positive effect on mechanical properties. The addition of copolymer increased the hydrophobicity when the total PVDF content was 20%. At 25% and with the inclusion of mixed-solvent, the hydrophobicity was adversely affected. The permeability of the membranes increased with the increase in the overall content of PVDF. Mixed-solvents significantly improved permeability.

  11. Environmentally sensitive probes for monitoring protein-membrane interactions at nanomolar concentrations

    Czech Academy of Sciences Publication Activity Database

    Shvadchak, Volodymyr V.; Kucherak, Oleksandr; Afitska, Kseniia; Dziuba, D.; Yushchenko, Dmytro A.

    2017-01-01

    Roč. 1859, č. 5 (2017), s. 852-859 ISSN 0005-2736 Institutional support: RVO:61388963 Keywords : solvatochromic probes * fluorescence * protein-membrane interaction * affinity * binding stoichiometry * alpha-synuclein Subject RIV: CE - Biochemistry OBOR OECD: Biochemistry and molecular biology Impact factor: 3.498, year: 2016

  12. Mathematical modeling of methyl ester concentration distribution in a continuous membrane tubular reactor and comparison with conventional tubular reactor

    Science.gov (United States)

    Talaghat, M. R.; Jokar, S. M.; Modarres, E.

    2017-10-01

    The reduction of fossil fuel resources and environmental issues made researchers find alternative fuels include biodiesels. One of the most widely used methods for production of biodiesel on a commercial scale is transesterification method. In this work, the biodiesel production by a transesterification method was modeled. Sodium hydroxide was considered as a catalyst to produce biodiesel from canola oil and methanol in a continuous tubular ceramic membranes reactor. As the Biodiesel production reaction from triglycerides is an equilibrium reaction, the reaction rate constants depend on temperature and related linearly to catalyst concentration. By using the mass balance for a membrane tubular reactor and considering the variation of raw materials and products concentration with time, the set of governing equations were solved by numerical methods. The results clearly show the superiority of membrane reactor than conventional tubular reactors. Afterward, the influences of molar ratio of alcohol to oil, weight percentage of the catalyst, and residence time on the performance of biodiesel production reactor were investigated.

  13. Pentraxin 3 concentrations of the mothers with preterm premature rupture of membranes and their neonates, and early neonatal outcome.

    Science.gov (United States)

    Akin, Mustafa Ali; Gunes, Tamer; Coban, Dilek; Ozgun, Mahmut Tuncay; Akgun, Hulya; Kurtoglu, Selim

    2015-07-01

    Pentraxin 3 (PTX3) is an acute phase reactant which has been used to detect intra-amniotic infections (IAI) in pregnancy, but the prognostic value of PTX3 concentrations on neonates has not been studied. We aimed to investigate the relationship between maternal PTX3-neonatal PTX3 concentrations and early neonatal outcome. The mothers diagnosed with preterm prelabor rupture of membranes (PPROM) (n = 28) and their preterm infants (n = 28) were included in the study. PTX3 concentrations were studied in plasma in the maternal peripheral blood and umbilical/peripheral vein in the neonates. The relationship between the mPTX3-nPTX3 concentrations and neonatal outcome were investigated using non-parametric tests and binary logistic regression analysis. The mean mPTX3 concentration was 10.35 ± 7.82 μg/L. Ten (35.7%) of all mothers were within the normal range and 18 (64.3%) in high percentile (≥ 97.5 percentile). There was no relation between mPTX3 concentrations and clinical or histologic chorioamnionitis, latency of PPROM, and early neonatal outcome. Mean nPTX3 concentrations was 9.18 ± 7.83 μg/L and high nPTX3 concentrations were detected in five (17.8%) neonates. nPTX3 concentrations were inversely correlated with gestational age and correlated with rate of intraventricular hemorrhage (IVH) and mortality. Neonates with high nPTX3 concentrations also have lowered APGAR scores, increased rate of respiratory distress syndrome, clinical sepsis, IVH, necrotizing enterocolitis and prolonged NICU stay. High PTX3 concentrations of the newborns are associated with some worsened early neonatal outcome including lower gestational age at delivery, increased rate of IVH and mortality. Maternal PTX3 concentrations are not an adequate marker in defining clinical or histologic chorioamnionitis and early neonatal outcome.

  14. Estimating the concentration of gold nanoparticles incorporated on natural rubber membranes using multi-level starlet optimal segmentation

    Energy Technology Data Exchange (ETDEWEB)

    Siqueira, A. F. de, E-mail: siqueiraaf@gmail.com; Cabrera, F. C., E-mail: flavioccabrera@yahoo.com.br [UNESP – Univ Estadual Paulista, Dep de Física, Química e Biologia (Brazil); Pagamisse, A., E-mail: aylton@fct.unesp.br [UNESP – Univ Estadual Paulista, Dep de Matemática e Computação (Brazil); Job, A. E., E-mail: job@fct.unesp.br [UNESP – Univ Estadual Paulista, Dep de Física, Química e Biologia (Brazil)

    2014-12-15

    This study consolidates multi-level starlet segmentation (MLSS) and multi-level starlet optimal segmentation (MLSOS) techniques for photomicrograph segmentation, based on starlet wavelet detail levels to separate areas of interest in an input image. Several segmentation levels can be obtained using MLSS; after that, Matthews correlation coefficient is used to choose an optimal segmentation level, giving rise to MLSOS. In this paper, MLSOS is employed to estimate the concentration of gold nanoparticles with diameter around 47  nm, reduced on natural rubber membranes. These samples were used for the construction of SERS/SERRS substrates and in the study of the influence of natural rubber membranes with incorporated gold nanoparticles on the physiology of Leishmania braziliensis. Precision, recall, and accuracy are used to evaluate the segmentation performance, and MLSOS presents an accuracy greater than 88 % for this application.

  15. Studies on as separation behaviour of polymer blending PI/PES hybrid mixed membrane: Effect of polymer concentration and zeolite loading

    Directory of Open Access Journals (Sweden)

    Ahmad Fauzi Ismail

    2014-04-01

    Full Text Available This study is performed primarily to investigate the effect of polymer concentration of polyimide/polyethersulfone (PI/PES blending on the gas separation performance of hybrid mixed matrix membrane. In this study, PI/ (PES–zeolite 4A mixed matrix membranes were casted using dry/wet phase inversion technique. The efefct of PI/PES concentrations and zeolite loading on the dope solution were investigated for gas separation performance. The results from the Field Emission Scanning Electron Microscopy (FESEM analysis confirmed that polymer concentration and zeolite loading was affected the morphology of membrane and gas separation performance. ‘Sieve-in-a-cage’ morphology observed the poor adhesion between polymer and zeolite at higher zeolite loading. The gas separation performance of the mixed matrix membranes were relatively higher compared to that of the neat polymeric membrane.

  16. Pu Anion Exchange Process Intensification

    International Nuclear Information System (INIS)

    Taylor-Pashow, Kathryn M. L.

    2017-01-01

    This research is focused on improving the efficiency of the anion exchange process for purifying plutonium. While initially focused on plutonium, the technology could also be applied to other ion-exchange processes. Work in FY17 focused on the improvement and optimization of porous foam columns that were initially developed in FY16. These foam columns were surface functionalized with poly(4-vinylpyridine) (PVP) to provide the Pu specific anion-exchange sites. Two different polymerization methods were explored for maximizing the surface functionalization with the PVP. The open-celled polymeric foams have large open pores and large surface areas available for sorption. The fluid passes through the large open pores of this material, allowing convection to be the dominant mechanism by which mass transport takes place. These materials generally have very low densities, open-celled structures with high cell interconnectivity, small cell sizes, uniform cell size distributions, and high structural integrity. These porous foam columns provide advantages over the typical porous resin beads by eliminating the slow diffusion through resin beads, making the anion-exchange sites easily accessible on the foam surfaces. The best performing samples exceeded the Pu capacity of the commercially available resin, and also offered the advantage of sharper elution profiles, resulting in a more concentrated product, with less loss of material to the dilute heads and tails cuts. An alternate approach to improving the efficiency of this process was also explored through the development of a microchannel array system for performing the anion exchange.

  17. Pu Anion Exchange Process Intensification

    Energy Technology Data Exchange (ETDEWEB)

    Taylor-Pashow, Kathryn M. L. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL)

    2017-10-06

    This research is focused on improving the efficiency of the anion exchange process for purifying plutonium. While initially focused on plutonium, the technology could also be applied to other ion-exchange processes. Work in FY17 focused on the improvement and optimization of porous foam columns that were initially developed in FY16. These foam columns were surface functionalized with poly(4-vinylpyridine) (PVP) to provide the Pu specific anion-exchange sites. Two different polymerization methods were explored for maximizing the surface functionalization with the PVP. The open-celled polymeric foams have large open pores and large surface areas available for sorption. The fluid passes through the large open pores of this material, allowing convection to be the dominant mechanism by which mass transport takes place. These materials generally have very low densities, open-celled structures with high cell interconnectivity, small cell sizes, uniform cell size distributions, and high structural integrity. These porous foam columns provide advantages over the typical porous resin beads by eliminating the slow diffusion through resin beads, making the anion-exchange sites easily accessible on the foam surfaces. The best performing samples exceeded the Pu capacity of the commercially available resin, and also offered the advantage of sharper elution profiles, resulting in a more concentrated product, with less loss of material to the dilute heads and tails cuts. An alternate approach to improving the efficiency of this process was also explored through the development of a microchannel array system for performing the anion exchange.

  18. Anion binding in biological systems

    Energy Technology Data Exchange (ETDEWEB)

    Feiters, Martin C [Department of Organic Chemistry, Institute for Molecules and Materials, Faculty of Science, Radboud University Nijmegen, Heyendaalseweg 135, 6525 AJ Nijmegen (Netherlands); Meyer-Klaucke, Wolfram [EMBL Hamburg Outstation at DESY, Notkestrasse 85, D-22607 Hamburg (Germany); Kostenko, Alexander V; Soldatov, Alexander V [Faculty of Physics, Southern Federal University, Sorge 5, Rostov-na-Donu, 344090 (Russian Federation); Leblanc, Catherine; Michel, Gurvan; Potin, Philippe [Centre National de la Recherche Scientifique and Universite Pierre et Marie Curie Paris-VI, Station Biologique de Roscoff, Place Georges Teissier, BP 74, F-29682 Roscoff cedex, Bretagne (France); Kuepper, Frithjof C [Scottish Association for Marine Science, Dunstaffnage Marine Laboratory, Oban, Argyll PA37 1QA, Scotland (United Kingdom); Hollenstein, Kaspar; Locher, Kaspar P [Institute of Molecular Biology and Biophysics, ETH Zuerich, Schafmattstrasse 20, Zuerich, 8093 (Switzerland); Bevers, Loes E; Hagedoorn, Peter-Leon; Hagen, Wilfred R, E-mail: m.feiters@science.ru.n [Department of Biotechnology, Delft University of Technology, Julianalaan 67, 2628 BC Delft (Netherlands)

    2009-11-15

    We compare aspects of biological X-ray absorption spectroscopy (XAS) studies of cations and anions, and report on some examples of anion binding in biological systems. Brown algae such as Laminaria digitata (oarweed) are effective accumulators of I from seawater, with tissue concentrations exceeding 50 mM, and the vanadate-containing enzyme haloperoxidase is implicated in halide accumulation. We have studied the chemical state of iodine and its biological role in Laminaria at the I K edge, and bromoperoxidase from Ascophyllum nodosum (knotted wrack) at the Br K edge. Mo is essential for many forms of life; W only for certain archaea, such as Archaeoglobus fulgidus and the hyperthermophilic archaeon Pyrococcus furiosus, and some bacteria. The metals are bound and transported as their oxo-anions, molybdate and tungstate, which are similar in size. The transport protein WtpA from P. furiosus binds tungstate more strongly than molybdate, and is related in sequence to Archaeoglobus fulgidus ModA, of which a crystal structure is known. We have measured A. fulgidus ModA with tungstate at the W L{sub 3} (2p{sub 3/2}) edge, and compared the results with the refined crystal structure. XAS studies of anion binding are feasible even if only weak interactions are present, are biologically relevant, and give new insights in the spectroscopy.

  19. Anion binding in biological systems

    International Nuclear Information System (INIS)

    Feiters, Martin C; Meyer-Klaucke, Wolfram; Kostenko, Alexander V; Soldatov, Alexander V; Leblanc, Catherine; Michel, Gurvan; Potin, Philippe; Kuepper, Frithjof C; Hollenstein, Kaspar; Locher, Kaspar P; Bevers, Loes E; Hagedoorn, Peter-Leon; Hagen, Wilfred R

    2009-01-01

    We compare aspects of biological X-ray absorption spectroscopy (XAS) studies of cations and anions, and report on some examples of anion binding in biological systems. Brown algae such as Laminaria digitata (oarweed) are effective accumulators of I from seawater, with tissue concentrations exceeding 50 mM, and the vanadate-containing enzyme haloperoxidase is implicated in halide accumulation. We have studied the chemical state of iodine and its biological role in Laminaria at the I K edge, and bromoperoxidase from Ascophyllum nodosum (knotted wrack) at the Br K edge. Mo is essential for many forms of life; W only for certain archaea, such as Archaeoglobus fulgidus and the hyperthermophilic archaeon Pyrococcus furiosus, and some bacteria. The metals are bound and transported as their oxo-anions, molybdate and tungstate, which are similar in size. The transport protein WtpA from P. furiosus binds tungstate more strongly than molybdate, and is related in sequence to Archaeoglobus fulgidus ModA, of which a crystal structure is known. We have measured A. fulgidus ModA with tungstate at the W L 3 (2p 3/2 ) edge, and compared the results with the refined crystal structure. XAS studies of anion binding are feasible even if only weak interactions are present, are biologically relevant, and give new insights in the spectroscopy.

  20. Anion binding in biological systems

    Science.gov (United States)

    Feiters, Martin C.; Meyer-Klaucke, Wolfram; Kostenko, Alexander V.; Soldatov, Alexander V.; Leblanc, Catherine; Michel, Gurvan; Potin, Philippe; Küpper, Frithjof C.; Hollenstein, Kaspar; Locher, Kaspar P.; Bevers, Loes E.; Hagedoorn, Peter-Leon; Hagen, Wilfred R.

    2009-11-01

    We compare aspects of biological X-ray absorption spectroscopy (XAS) studies of cations and anions, and report on some examples of anion binding in biological systems. Brown algae such as Laminaria digitata (oarweed) are effective accumulators of I from seawater, with tissue concentrations exceeding 50 mM, and the vanadate-containing enzyme haloperoxidase is implicated in halide accumulation. We have studied the chemical state of iodine and its biological role in Laminaria at the I K edge, and bromoperoxidase from Ascophyllum nodosum (knotted wrack) at the Br K edge. Mo is essential for many forms of life; W only for certain archaea, such as Archaeoglobus fulgidus and the hyperthermophilic archaeon Pyrococcus furiosus, and some bacteria. The metals are bound and transported as their oxo-anions, molybdate and tungstate, which are similar in size. The transport protein WtpA from P. furiosus binds tungstate more strongly than molybdate, and is related in sequence to Archaeoglobus fulgidus ModA, of which a crystal structure is known. We have measured A. fulgidus ModA with tungstate at the W L3 (2p3/2) edge, and compared the results with the refined crystal structure. XAS studies of anion binding are feasible even if only weak interactions are present, are biologically relevant, and give new insights in the spectroscopy.

  1. Roles of Organic Acid Anion Secretion in Aluminium Tolerance of Higher Plants

    Science.gov (United States)

    Yang, Lin-Tong; Qi, Yi-Ping; Jiang, Huan-Xin; Chen, Li-Song

    2013-01-01

    Approximately 30% of the world's total land area and over 50% of the world's potential arable lands are acidic. Furthermore, the acidity of the soils is gradually increasing as a result of the environmental problems including some farming practices and acid rain. At mildly acidic or neutral soils, aluminium(Al) occurs primarily as insoluble deposits and is essentially biologically inactive. However, in many acidic soils throughout the tropics and subtropics, Al toxicity is a major factor limiting crop productivity. The Al-induced secretion of organic acid (OA) anions, mainly citrate, oxalate, and malate, from roots is the best documented mechanism of Al tolerance in higher plants. Increasing evidence shows that the Al-induced secretion of OA anions may be related to the following several factors, including (a) anion channels or transporters, (b) internal concentrations of OA anions in plant tissues, (d) temperature, (e) root plasma membrane (PM) H+-ATPase, (f) magnesium (Mg), and (e) phosphorus (P). Genetically modified plants and cells with higher Al tolerance by overexpressing genes for the secretion and the biosynthesis of OA anions have been obtained. In addition, some aspects needed to be further studied are also discussed. PMID:23509687

  2. Effect of sulphuric acid concentration on electroosmotic flow through polymer electrolyte membranes in PEM fuel cells. Paper no. IGEC-1-061

    International Nuclear Information System (INIS)

    Karimi, G.; Li, X.

    2005-01-01

    Polymer electrolyte membrane (PEM) fuel cells are highly efficient and environmentally clean, and hence one of the most promising power sources for both stationary and mobile applications. The operations of PEM fuel cells are complicated by the electroosmotic flow of water from anode to cathode through the polymer electrolyte membrane leading to the membrane dehydration and fuel cell performance degradations. In this study, electro osmotic flow in polymer electrolyte membranes is modeled by incorporating the electro kinetic effects in the presence of euphoric acid. The governing Poisson-Boatman and the Nervier-Stokes equations were solved numerically for a single membrane pore to determine the electro osmotic flow distributions through the membrane over a wide range of acid concentrations. The presence of euphoric acid modifies the protons distribution in the membrane and hence alters the driving force for electroosmotic drag. Numerical results indicate that the electro osmotic flow increases steadily with acid concentration. The water transport due to electro osmosis is almost doubled at 2 M acid concentration compared with that of non-doped membrane. The value of electroosmotic drag coefficient however falls steadily with acid concentration due to the presence of a larger number of protons in the electrolyte. (author)

  3. Handling of membrane concentrate from reclamation of water in polyester dyeing

    DEFF Research Database (Denmark)

    Villanueva, Alejandro; Wenzel, Henrik; Knudsen, Hans Henrik

    2003-01-01

    incineration, wet air oxidation, activated carbon, transport to hazardous waste treatment facility, and drying for zero-discharge. In most disposal scenarios considered it is advantageous to dewater the concentrate further from 2,5 %DS (dry solids) to 20 %DS in order to reduce its volume and thereby diminish...... recycling projects where the concentrate has low or no commercial value. In the scenarios analyzed, concentrate disposal costs represents between 10% and 70% of the total treatment costs per m3 of water recycled. It is therefore recommended to analyze in detail the available alternatives for concentrate...

  4. Handling of Membrane Concentrate from Reclamation of Water in Polyester Dyeing

    DEFF Research Database (Denmark)

    Villanueva, Alejandro; Wenzel, Henrik; Knudsen, Hans Henrik

    2003-01-01

    incineration, wet air oxidation, activated carbon, transport to hazardous waste treatment facility, and drying for zero-discharge. In most disposal scenarios considered it is advantageous to dewater the concentrate further from 2,5 %DS (dry solids) to 20 %DS in order to reduce its volume and thereby diminish...... recycling projects where the concentrate has low or no commercial value. In the scenarios analyzed, concentrate disposal costs represents between 10% and 70% of the total treatment costs per m3 of water recycled. It is therefore recommended to analyze in detail the available alternatives for concentrate...

  5. Bipolar membranes in forward bias region for fuel cell reactors

    International Nuclear Information System (INIS)

    Lobyntseva, Elena; Kallio, Tanja; Kontturi, Kyoesti

    2006-01-01

    Three bipolar membranes, two home-made composed of commercial cation (DuPont) and anion (FuMA-Tech) exchange membranes (called Nafion/FT-FAA and Nafion/FT-FAS) and a commercial one, BP-1 from FuMA-Tech, were investigated in order to characterize their suitability to use in a H 2 /O 2 fuel cell intended to produce hydrogen peroxide on the cathode instead of water. The Nafion/FT-FAA and Nafion/FT-FAS membranes were prepared using a hot-pressing method. The optimal hot-pressing conditions were determined by measuring the ionic conductivity of the membranes. The latter was observed to depend on the relative humidity of the bipolar membrane. Of the studied bipolar membranes, Nafion/FT-FAA showed the best performance. The transport number of protons measured in a concentration cell was observed to depend on the direction of the proton diffusion flux through these membranes so that transport numbers of ca. unity were obtained when the cation exchange side faced the solution with higher proton concentration. In the opposite case, when the higher concentration faced anion exchange side, the transport number of proton was clearly lower, indicating the usefulness of the bipolar membranes for hydrogen peroxide production in the fuel cell

  6. A pilot-scale forward osmosis membrane system for concentrating low-strength municipal wastewater: performance and implications

    Science.gov (United States)

    Wang, Zhiwei; Zheng, Junjian; Tang, Jixu; Wang, Xinhua; Wu, Zhichao

    2016-02-01

    Recovery of nutrients and energy from municipal wastewater has attracted much attention in recent years; however, its efficiency is significantly limited by the low-strength properties of municipal wastewater. Herein, we report a pilot-scale forward osmosis (FO) system using a spiral-wound membrane module to concentrate real municipal wastewater. Under active layer facing feed solution mode, the critical concentration factor (CCF) of this FO system was determined to be 8 with 0.5 M NaCl as draw solution. During long-term operation at a concentration factor of 5, (99.8 ± 0.6)% of chemical oxygen demand and (99.7 ± 0.5)% of total phosphorus rejection rates could be achieved at a flux of 6 L/(m2 h) on average. In comparison, only (48.1 ± 10.5)% and (67.8 ± 7.3)% rejection of ammonium and total nitrogen were observed. Cake enhanced concentration polarization is a major contributor to the decrease of water fluxes. The fouling also led to the occurrence of a cake reduced concentration polarization effect, improving ammonium rejection rate with the increase of operation time in each cycle. This work demonstrates the applicability of using FO process for wastewater concentrating and also limitations in ammonium recovery that need further improvement in future.

  7. Electrodialysis of boron-containing solutions using homogeneuos ionite membranes

    International Nuclear Information System (INIS)

    Pilipenko, A.T.; Grebenyuk, V.D.; Mel'nik, L.A.

    1989-01-01

    Electrodialysis of boron-containing solutions is studied when preparing potable water from the sea one with the limiting admissible concentration (LAC) of boron 0.5 mg/dm 3 . It is ascertained that at pH>7 diffusion permeability of anion- and cation-exchange membranes as regards boron reduces both in the absence of external field and at current density 0.3 A/dm 3 . It is shown that when MK-100 homogeneous cationic membranes and MA-100 homogeneous anionic membranes are used, boron concentration in dialyzate decreases to LAC, if the process is realized in acid and low-acid media and if the depth of freshening increases to 0.2g/l

  8. Application of the CMPO extractant (supported liquid membrane) for the alpha decontamination of marcoule reprocessing concentrate

    International Nuclear Information System (INIS)

    Dozol, J.F.

    1990-01-01

    Reprocessing operations produce medium activity liquid wastes, in which the main components are sodium nitrate and nitric acid. These wastes are treated by evaporation, the distillate is discharged in the environment and all active and inactive salts are concentrated, leading to an important volume of wastes. The overall objective of this work, carried out within the framework of an CEC contract is to separate long life radionuclides (actinides and Cs - Sr) into a small volume from the large volume of the concentrate

  9. Spectrophotometric flow-injection determination of sulphite in white wines involving gas diffusion through a concentric tubular membrane

    Directory of Open Access Journals (Sweden)

    Melo Denise

    2003-01-01

    Full Text Available A flow-injection system is proposed for the spectrophotometric determination of sulphite in white wines. The method involves analyte conversion to SO2, gas diffusion through a Teflon® semi-permeable membrane, collection into an alkaline stream (pH 8, reaction with Malachite green (MG and monitoring at 620 nm. With a concentric tubular membrane, the system design was simplified. Influence of reagent concentrations, pH of donor and acceptor streams, temperature, timing, surfactant addition and presence of potential interfering species of the wine matrix were investigated. A pronounced (ca. 100% enhancement in sensitivity was noted by adding cetylpyridinium chloride (CPC. The proposed system is robust and baseline drift is not observed during 4 h operating periods. Only 400 muL of sample and 0.32 mg MG are required per determination. The system handles 30 samples per hour, yielding precise results (r.s.d. < 0.015 for 1.0 - 20.0 mg L-1 SO2 in agreement with those obtained by an alternative procedure.

  10. Wheat germ cell-free expression: Two detergents with a low critical micelle concentration allow for production of soluble HCV membrane proteins.

    Science.gov (United States)

    Fogeron, Marie-Laure; Badillo, Aurélie; Jirasko, Vlastimil; Gouttenoire, Jérôme; Paul, David; Lancien, Loick; Moradpour, Darius; Bartenschlager, Ralf; Meier, Beat H; Penin, François; Böckmann, Anja

    2015-01-01

    Membrane proteins are notoriously difficult to express in a soluble form. Here, we use wheat germ cell-free expression in the presence of various detergents to produce the non-structural membrane proteins 2, 4B and 5A of the hepatitis C virus (HCV). We show that lauryl maltose neopentyl glycol (MNG-3) and dodecyl octaethylene glycol ether (C12E8) detergents can yield essentially soluble membrane proteins at detergent concentrations that do not inhibit the cell-free reaction. This finding can be explained by the low critical micelle concentration (CMC) of these detergents, which keeps the monomer concentrations low while at the same time providing the necessary excess of detergent concentration above CMC required for full target protein solubilization. We estimate that a tenfold excess of detergent micelles with respect to the protein concentration is sufficient for solubilization, a number that we propose as a guideline for detergent screening assays. Copyright © 2014 Elsevier Inc. All rights reserved.

  11. Integrated Disinfection Byproducts (DBPs) Mixtures Research: DBP Concentration via Reverse Osmosis Membrane Techniques

    Science.gov (United States)

    With the completion of the 4-lab project, the NOM concentration aspect of 4-lab is being continued with renewed focus on creating drinking water relevant freeze-dried NOM isolates that can be used for many drinking water research efforts from DBP investigations to water reuse inv...

  12. Anaerobic membrane bioreactors and the influence of space velocity and biomass concentration on methane production for liquid dairy manure

    International Nuclear Information System (INIS)

    Wallace, James M.; Safferman, Steven I.

    2014-01-01

    Two pilot-scale anaerobic membrane bioreactors (AnMBRs) and a control completely mixed digester (CMD) were constructed to evaluate the influence of space velocity and biomass concentration on methane production for sand separated dairy manure. A negative impact on methane production resulted with operating the AnMBR system at 972 μHz–2960 μHz but no impact was found when operating at 69 μHz and 312 μHz. Operating at 69 μHz–350 μHz is realistic for a field installation. Despite the higher biomass concentration, the methane production of the AnMBRs was nearly equal to the CMD. An AnMBR with 69 μHz was operated equivalent to a CMD by returning all permeate to the digester tank and removing excess biomass directly from the reactor tank resulting in a hydraulic retention time (HRT) equal to the solids retention time (SRT). When using sand separated dairy manure and an HRT (and equal SRT) of 12 d, both systems produced methane at an equal rate, suggesting that the pump/membrane system did not influence methane production. The most likely reason was mass transfer limitations of hydrolytic enzymes. Based on methane production and volatile fatty acids analysis, it appears the fermentable substrate available for degradation was similar. The AnMBR proved to have benefit as part of an integrated nutrient management system that produced water that is virtually free of particulate nutrients, especially phosphorus. This enables the irrigation of the water to crops that need nitrogen and the efficient movement of phosphorus, as a solid, to needed locations. - Highlights: • Manure AnMBRs with a high space velocity inhibit methane production. • Manure AnMBRs with a low space velocity perform similar to conventional digesters. • Decoupled HRT and SRT in manure AnMBRs do not increase methane production. • Ultrafiltration membranes effectively partitioned manure nutrients from the liquid. • Manure does not foul ultrafiltration membranes and require mild

  13. Facilitated transport of hydrophilic salts by mixtures of anion and cation carriers and by ditopic carriers

    NARCIS (Netherlands)

    Chrisstoffels, L.A.J.; de Jong, Feike; Reinhoudt, David; Sivelli, Stefano; Gazzola, Licia; Casnati, Alessandro; Ungaro, Rocco

    1999-01-01

    Anion transfer to the membrane phase affects the extraction efficiency of salt transport by cation carriers 1 and 3. Addition of anion receptors 5 or 6 to cation carriers 1, 3, or 4 in the membrane phase enhances the transport of salts under conditions in which the cation carriers alone do not

  14. Electrochemical oxidation of biological pretreated and membrane separated landfill leachate concentrates on boron doped diamond anode

    Energy Technology Data Exchange (ETDEWEB)

    Zhou, Bo, E-mail: 357436235@qq.com [School of Materials Science and Engineering, Central South University, Changsha 410083 (China); Yu, Zhiming, E-mail: zhiming@csu.edu.cn [School of Materials Science and Engineering, Central South University, Changsha 410083 (China); State Key Laboratory of Powder Metallurgy, Central South University, Changsha 410083 (China); Wei, Qiuping, E-mail: qiupwei@csu.edu.cn [School of Materials Science and Engineering, Central South University, Changsha 410083 (China); State Key Laboratory of Powder Metallurgy, Central South University, Changsha 410083 (China); Long, HangYu, E-mail: 55686385@qq.com [School of Materials Science and Engineering, Central South University, Changsha 410083 (China); Xie, Youneng, E-mail: 1187272844@qq.com [School of Materials Science and Engineering, Central South University, Changsha 410083 (China); Wang, Yijia, E-mail: 503630433@qq.com [School of Materials Science and Engineering, Central South University, Changsha 410083 (China)

    2016-07-30

    Highlights: • High quality boron-doped diamond film electrodes were synthesized on Nb substrates. • Electrochemical oxidation on boron-doped diamond anode is an effective method for treating landfill leachate concentrates. • Optimal operating conditions for electrochemical oxidation of landfill leachate concentrates is determined. • 87.5% COD removal and 74.06% NH{sub 3}−N removal were achieved after 6 h treatment. - Abstract: In the present study, the high quality boron-doped diamond (BDD) electrodes with excellent electrochemical properties were deposited on niobium (Nb) substrates by hot filament chemical vapor deposition (HFCVD) method. The electrochemical oxidation of landfill leachate concentrates from disc tube reverse osmosis (DTRO) process over a BDD anode was investigated. The effects of varying operating parameters, such as current density, initial pH, flow velocity and cathode material on degradation efficiency were also evaluated following changes in chemical oxygen demand (COD) and ammonium nitrogen (NH{sub 3}−N). The instantaneous current efficiency (ICE) was used to appraise different operating conditions. As a result, the best conditions obtained were as follows, current density 50 mA cm{sup −2}, pH 5.16, flow velocity 6 L h{sup −1}. Under these conditions, 87.5% COD and 74.06% NH{sub 3}−N removal were achieved after 6 h treatment, with specific energy consumption of 223.2 kWh m{sup −3}. In short, these results indicated that the electrochemical oxidation with BDD/Nb anode is an effective method for the treatment of landfill leachate concentrates.

  15. Genotoxicity assessment of membrane concentrates of landfill leachate treated with Fenton reagent and UV-Fenton reagent using human hepatoma cell line

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Guifang [Department of Chemistry, Jinan University, Guangzhou 510632 (China); Lu, Gang [Key Laboratory of Water/Soil Toxic Pollutants Control and Bioremediation of Guangdong Higher Education Institutes, Department of Environmental Engineering, Jinan University, Guangzhou 510632 (China); Yin, Pinghe, E-mail: tyinph@jnu.edu.cn [Research Center of Analysis and Test, Jinan University, Guangzhou 510632 (China); Zhao, Ling, E-mail: zhaoling@jnu.edu.cn [Key Laboratory of Water/Soil Toxic Pollutants Control and Bioremediation of Guangdong Higher Education Institutes, Department of Environmental Engineering, Jinan University, Guangzhou 510632 (China); Jimmy Yu, Qiming [Griffith School of Engineering, Griffith University, Nathan Campus, Brisbane, Queensland 4111 (Australia)

    2016-04-15

    Highlights: • Membrane concentrates have a threat to human health and environment. • Untreated membrane concentrates induces cytotoxic and genotoxic to HepG2 cells. • Both methods were effective method for degradation of BPA and NP in concentrates. • Both methods were efficient in reducing genotoxic effects of concentrates. • UV-Fenton reagent had higher removal efficiency and provides toxicological safety. - Abstract: Membrane concentrates of landfill leachates contain organic and inorganic contaminants that could be highly toxic and carcinogenic. In this paper, the genotoxicity of membrane concentrates before and after Fenton and UV-Fenton reagent was assessed. The cytotoxicity and genotoxicity was determined by using the methods of methyltetrazolium (MTT), cytokinesis-block micronucleus (CBMN) and comet assay in human hepatoma cells. MTT assay showed a cytotoxicity of 75% after 24 h of exposure to the highest tested concentration of untreated concentrates, and no cytotoxocity for UV-Fenton and Fenton treated concentrates. Both CBMN and comet assays showed increased levels of genotoxicity in cells exposed to untreated concentrates, compared to those occurred in cells exposed to UV-Fenton and Fenton reagent treated concentrates. There was no significant difference between negative control and UV-Fenton treated concentrates for micronucleus and comet assay parameters. UV-Fenton and Fenton treatment, especially the former, were effective methods for degradation of bisphenol A and nonylphenol in concentrates. These findings showed UV-Fenton and Fenton reaction were effective methods for treatment of such complex concentrates, UV-Fenton reagent provided toxicological safety of the treated effluent, and the genotoxicity assays were found to be feasible tools for assessment of toxicity risks of complex concentrates.

  16. Genotoxicity assessment of membrane concentrates of landfill leachate treated with Fenton reagent and UV-Fenton reagent using human hepatoma cell line

    International Nuclear Information System (INIS)

    Wang, Guifang; Lu, Gang; Yin, Pinghe; Zhao, Ling; Jimmy Yu, Qiming

    2016-01-01

    Highlights: • Membrane concentrates have a threat to human health and environment. • Untreated membrane concentrates induces cytotoxic and genotoxic to HepG2 cells. • Both methods were effective method for degradation of BPA and NP in concentrates. • Both methods were efficient in reducing genotoxic effects of concentrates. • UV-Fenton reagent had higher removal efficiency and provides toxicological safety. - Abstract: Membrane concentrates of landfill leachates contain organic and inorganic contaminants that could be highly toxic and carcinogenic. In this paper, the genotoxicity of membrane concentrates before and after Fenton and UV-Fenton reagent was assessed. The cytotoxicity and genotoxicity was determined by using the methods of methyltetrazolium (MTT), cytokinesis-block micronucleus (CBMN) and comet assay in human hepatoma cells. MTT assay showed a cytotoxicity of 75% after 24 h of exposure to the highest tested concentration of untreated concentrates, and no cytotoxocity for UV-Fenton and Fenton treated concentrates. Both CBMN and comet assays showed increased levels of genotoxicity in cells exposed to untreated concentrates, compared to those occurred in cells exposed to UV-Fenton and Fenton reagent treated concentrates. There was no significant difference between negative control and UV-Fenton treated concentrates for micronucleus and comet assay parameters. UV-Fenton and Fenton treatment, especially the former, were effective methods for degradation of bisphenol A and nonylphenol in concentrates. These findings showed UV-Fenton and Fenton reaction were effective methods for treatment of such complex concentrates, UV-Fenton reagent provided toxicological safety of the treated effluent, and the genotoxicity assays were found to be feasible tools for assessment of toxicity risks of complex concentrates.

  17. Improvement on the concentrated grape juice physico-chemical characteristics by an enzymatic treatment and Membrane Separation Processes

    Directory of Open Access Journals (Sweden)

    PLÍNIO R.F. CAMPOS

    2016-03-01

    Full Text Available ABSTRACT In this work, the improvement on the concentrated grape juice physico-chemical characteristics by using an enzymatic treatment followed by Membrane Separation Process (MSP has been investigated. By using Novozym 33095(r and Ultrazym AFP L(r enzymes varying three operating parameters, the best result on the grape pulp characteristics was attained for the Novozym 33095(r performed at 35oC, 15 min. and 50 mgL-1. In micro/ultra filtration processes after enzymatic pretreatment, the best performance of the MSP with high permeate flux value and suitable grape juice characteristics was attained using 0.05 mm membrane pore size, 1 bar pressure and 40 oC treatment temperature. When reverse osmosis process is operated at 40 bar and 40oC, high soluble solid and low turbidity values are attained. An enzymatic treatment along with MSP has shown an alternative and efficient grape juice processing system, being possible to extend to other foods.

  18. Impact of low-concentrated acidic electrolysed water obtained by membrane electrolysis on the decontamination of meat microbiota

    Directory of Open Access Journals (Sweden)

    Brychcy Ewa

    2015-09-01

    Full Text Available The influence of acidic electrolysed water (AEW treatment on inactivation of pure bacterial cultures inoculated onto the surface of agarised media and surface microbiota of pork meat were examined. Low-concentrated AEW (low concentration of sodium chloride and low current electrolysis was generated by electrolysis (5 or 10 min of 0.001% or 0.01% NaCl solution. The number of viable microorganisms was determined using a plate count method. The effect of AEW on bacterial cell morphology were investigated using scanning electron microscopy (SEM. After treatment with AEW, a significant, about 3.00 log reduction of Pseudomonas fluorescens, Yersinia enterocolitica, Escherichia coli, Staphylococcus aureus, Bacillus subtilis, Listeria monocytogenes, and Micrococcus luteus populations was observed. In the AEW treatment of pork, the highest reduction of total number of microorganisms (2.1 log reduction, yeast and moulds (2.5-2.6 log reduction, and psychrotrophs (more than 1 log reduction was observed after spraying with 0.001% NaCl subjected to 10 min electrolysis. SEM revealed disruption and lysis of E. coli and S. aureus cells treated with AEW, suggesting a bactericidal effect. Higher available chlorine concentration (0.37-8.45 mg/L, redox potential (863.1-1049.8 mV, and lower pH (2.73-3.70 had an influence on the shape of bacteria and the number of breaks in the bacterial membrane.

  19. Laboratory-scale membrane up-concentration and co-anaerobic digestion for energy recovery from sewage and kitchen waste.

    Science.gov (United States)

    Tuyet, Nguyen Thi; Dan, Nguyen Phuoc; Vu, Nguyen Cong; Trung, Nguyen Le Hoang; Thanh, Bui Xuan; De Wever, Heleen; Goemans, Marcel; Diels, Ludo

    2016-01-01

    This study assessed an alternative concept for co-treatment of sewage and organic kitchen waste in Vietnam. The goal was to apply direct membrane filtration for sewage treatment to generate a permeate that is suitable for discharge. The obtained chemical oxygen demand (COD) concentrations in the permeate of ultrafiltration tests were indeed under the limit value (50 mg/L) of the local municipal discharge standards. The COD of the concentrate was 5.4 times higher than that of the initial feed. These concentrated organics were then co-digested with organic kitchen wastes at an organic loading rate of 2.0 kg VS/m(3).d. The volumetric biogas production of the digester was 1.94 ± 0.34 m(3)/m(3).d. The recovered carbon, in terms of methane gas, accounted for 50% of the total carbon input of the integrated system. Consequently, an electrical production of 64 Wh/capita/d can be obtained when applying the proposed technology with the current wastes generated in Ho Chi Minh City. Thus, it is an approach with great potential in terms of energy recovery and waste treatment.

  20. Electrochemical activation and inhibition of neuromuscular systems through modulation of ion concentrations with ion-selective membranes

    Science.gov (United States)

    Song, Yong-Ak; Melik, Rohat; Rabie, Amr N.; Ibrahim, Ahmed M. S.; Moses, David; Tan, Ara; Han, Jongyoon; Lin, Samuel J.

    2011-12-01

    Conventional functional electrical stimulation aims to restore functional motor activity of patients with disabilities resulting from spinal cord injury or neurological disorders. However, intervention with functional electrical stimulation in neurological diseases lacks an effective implantable method that suppresses unwanted nerve signals. We have developed an electrochemical method to activate and inhibit a nerve by electrically modulating ion concentrations in situ along the nerve. Using ion-selective membranes to achieve different excitability states of the nerve, we observe either a reduction of the electrical threshold for stimulation by up to approximately 40%, or voluntary, reversible inhibition of nerve signal propagation. This low-threshold electrochemical stimulation method is applicable in current implantable neuroprosthetic devices, whereas the on-demand nerve-blocking mechanism could offer effective clinical intervention in disease states caused by uncontrolled nerve activation, such as epilepsy and chronic pain syndromes.

  1. Ion Transport through Diffusion Layer Controlled by Charge Mosaic Membrane

    Directory of Open Access Journals (Sweden)

    Akira Yamauchi

    2012-01-01

    Full Text Available The kinetic transport behaviors in near interface of the membranes were studied using commercial anion and cation exchange membrane and charge mosaic membrane. Current-voltage curve gave the limiting current density that indicates the ceiling of conventional flux. From chronopotentiometry above the limiting current density, the transition time was estimated. The thickness of boundary layer was derived with conjunction with the conventional limiting current density and the transition time from steady state flux. On the other hand, the charge mosaic membrane was introduced in order to examine the ion transport on the membrane surface in detail. The concentration profile was discussed by the kinetic transport number with regard to the water dissociation (splitting on the membrane surface.

  2. Concentration of membrane antigens by forward transport and trapping in neuronal growth cones.

    Science.gov (United States)

    Sheetz, M P; Baumrind, N L; Wayne, D B; Pearlman, A L

    1990-04-20

    Formation of the nervous system requires that neuronal growth cones follow specific paths and then stop at recognition signals, sensed at the growth cone's leading edge. We used antibody-coated gold particles viewed by video-enhanced differential interference contrast microscopy to observe the distribution and movement of two cell surface molecules, N-CAM and the 2A1 antigen, on growth cones of cultured cortical neurons. Gold particles are occasionally transported forward at 1-2 microns/s to the leading edge where they are trapped but continue to move. Concentration at the edge persists after cytochalasin D treatment or ATP depletion, but active movements to and along edges cease. We also observed a novel outward movement of small cytoplasmic aggregates at 1.8 microns/s in filopodia. We suggest that active forward transport and trapping involve reversible attachment of antigens to and transport along cytoskeletal elements localized to edges of growth cones.

  3. A highly phosphorylated subpopulation of insulin-like growth factor II/mannose 6-phosphate receptors is concentrated in a clathrin-enriched plasma membrane fraction

    International Nuclear Information System (INIS)

    Corvera, S.; Folander, K.; Clairmont, K.B.; Czech, M.P.

    1988-01-01

    Insulin-like growth factor II (IGF-II)/mannose 6-phosphate (Man-6-P) receptors immunoprecipitated from purified plasma membranes of 32 P-labeled rat adipocytes are markedly heterogenous in their phosphorylation state. Approximately 80% of the plasma membrane receptors are solubilized in 1% (vol/vol) Triton X-100 and are phosphorylated on serine residues at a stoichiometry of ∼ 0.1-0.2 mol of phosphate per mol of receptor. In contrast, 15-20% of the receptors are Triton X-100-insoluble and are phosphorylated on serine and threonine residues at ∼ 4 or 5 mol of phosphate per mol of receptor. This Triton X-100-insoluble membrane subfraction contains only 5% of the total plasma membrane protein and yet contains all of the clathrin heavy chain associated with plasma membrane. Based on the relative yields of protein in the detergent-insoluble material, IGF-II/Man-6-P receptors are concentrated ∼ 3-fold in this clathrin-enriched subfraction. Taken together, these results indicate that insulin decreases the phosphorylation state of a highly phosphorylated subpopulation of IGF-II/Man-6-P receptors on the plasma membrane. In addition, insulin action may prevent the concentration of these receptors in a clathrin-enriched membrane subfraction

  4. [Effect of high magnesium ion concentration on the electron transport rate and proton exchange in thylakoid membranes in higher plants].

    Science.gov (United States)

    Ignat'ev, A R; Khorobrykh, S A; Ivanov, B N

    2001-01-01

    The effects of magnesium ion concentration on the rate of electron transport in isolated pea thylakoids were investigated in the pH range from 4.0 up to 8.0. In the absence of magnesium ions in the medium and in the presence of 5 mM MgCl2 in the experiments not only without added artificial acceptors but also with ferricyanide or methylviologen as an acceptor, this rate had a well-expressed maximum at pH 5.0. It was shown that, after depression to minimal values at pH 5.5-6.5, it gradually rose with increasing pH. An increase in magnesium ion concentration up to 20 mM essentially affected the electron transfer rate: it decreased somewhat at pH 4.0-5.0 but increased at higher pH values. At this magnesium ion concentration, the maximum rate was at pH 6.0-6.5 and the minimum, at pH 7.0. Subsequent rise upon increasing pH to 8.0 was expressed more sharply. The influence of high magnesium ion concentration on the rate of electron transport was not observed in the presence of gramicidin D. It was found that without uncoupler, the changes in the electron transfer rate under the influence of magnesium ions correlated to the changes in the first-order rate constant of the proton efflux from thylakoids. It is supposed that the change in the ability of thylakoids to keep protons by the action of magnesium ions is the result of electrostatic interactions of these ions with the charges on the external surface of membranes. A possible role of regulation of the electron transport rate by magnesium ions in vivo is discussed.

  5. Maternal serum C-reactive protein concentration and intra-amniotic inflammation in women with preterm prelabor rupture of membranes.

    Directory of Open Access Journals (Sweden)

    Ivana Musilova

    Full Text Available To evaluate maternal serum C-reactive protein (CRP concentrations in pregnancies complicated by preterm prelabor rupture of membranes (PPROM in relation to the presence of microbial invasion of the amniotic cavity (MIAC and/or intra-amniotic inflammation (IAI.Two hundred and eighty-seven women with singleton pregnancies complicated by PPROM between 2014 and 2016 were included in this study. Maternal blood and amniotic fluid samples were collected at the time of admission. Maternal serum CRP concentration was measured using a high-sensitivity immunoturbidimetric assay. Interleukin-6 (IL-6 concentration was measured using a point-of-care test. MIAC was diagnosed based on a positive polymerase chain reaction result for Ureaplasma species, Mycoplasma hominis, and/or Chlamydia trachomatis and for the 16S rRNA gene. IAI was characterized by an amniotic fluid IL-6 concentration of ≥ 745 pg/mL.Women with MIAC and IAI had higher maternal serum CRP concentrations than did women without (with MIAC: median 6.9 mg/L vs. without MIAC: median 4.9 mg/L; p = 0.02; with IAI: median 8.6 mg/L vs. without IAI: median 4.7 mg/L; p < 0.0001. When women were split into four subgroups based on the presence of MIAC and/or IAI, women with the presence of both MIAC and IAI had higher maternal serum CRP than did women with IAI alone, with MIAC alone, and women without MIAC and IAI (both MIAC and IAI: median: 13.1 mg/L; IAI alone: 6.0 mg/L; MIAC alone: 3.9 mg/L; and without MIAC and IAI: median 4.8 mg/L; p < 0.0001. The maternal serum CRP cutoff value of 17.5 mg/L was the best level to identify the presence of both MIAC and IAI, with sensitivity of 47%, specificity of 96%, positive predictive value of 42%, negative predictive value of 96%, and the positive likelihood ratio of 10.9.The presence of both MIAC and IAI was associated with the highest maternal serum CRP concentrations. Maternal serum CRP concentration in women with PPROM at the time of admission can rule out the

  6. Superoxide anion production by human neutrophils activated by Trichomonas vaginalis.

    Science.gov (United States)

    Song, Hyun-Ouk; Ryu, Jae-Sook

    2013-08-01

    Neutrophils are the predominant inflammatory cells found in vaginal discharges of patients infected with Trichomonas vaginalis. In this study, we examined superoxide anion (O2 (.-)) production by neutrophils activated by T. vaginalis. Human neutrophils produced superoxide anions when stimulated with either a lysate of T. vaginalis, its membrane component (MC), or excretory-secretory product (ESP). To assess the role of trichomonad protease in production of superoxide anions by neutrophils, T. vaginalis lysate, ESP, and MC were each pretreated with a protease inhibitor cocktail before incubation with neutrophils. Superoxide anion production was significantly decreased by this treatment. Trichomonad growth was inhibited by preincubation with supernatants of neutrophils incubated for 3 hr with T. vaginalis lysate. Furthermore, myeloperoxidase (MPO) production by neutrophils was stimulated by live trichomonads. These results indicate that the production of superoxide anions and MPO by neutrophils stimulated with T. vaginalis may be a part of defense mechanisms of neutrophils in trichomoniasis.

  7. Beneficial phosphate recovery from reverse osmosis (RO) concentrate of an integrated membrane system using polymeric ligand exchanger (PLE).

    Science.gov (United States)

    Kumar, Manish; Badruzzaman, Mohammad; Adham, Samer; Oppenheimer, Joan

    2007-05-01

    Phosphorus (P) discharge to surface water is a major environmental problem. Wastewater treatment is targeted towards removal of this nutrient to prevent degradation of surface water. Integrated membrane systems (IMS) are increasingly being considered for wastewater reclamation, and provide excellent removal of P compounds. However, reverse osmosis (RO), which forms an integral part of these IMSs, concentrates most dissolved substances including P-species such as phosphates in the RO waste stream. In this study, removal of phosphate from this stream using polymeric ligand exchange (PLE) resins was investigated. Further, the possibility of phosphate recovery through struvite (MgNH(4)PO(4).6H(2)O) precipitation was tested. Struvite has been promoted as a slow release fertilizer in recent years. This study demonstrates that PLEs can be successfully used to remove phosphate from RO-concentrate, and to recover more than 85% of the adsorbed phosphorus from the exhausted media and precipitated as a beneficial product (struvite). The approach, presented in this study, suggests advantages of providing economic benefit from a waste product (RO) while avoiding phosphorus discharge to the environment.

  8. Development of anionic membranes produced by radiation-grafting for alkaline fuel cell applications; Desenvolvimento de membranas aniônicas obtidas por enxertia via irradiação para aplicação em células a combustível alcalinas

    Energy Technology Data Exchange (ETDEWEB)

    Pereira, Clotilde Coppini

    2017-07-01

    Anion Exchange Membranes (AEMs) are a promising alternative to the development of more efficient electrolytes for alkaline fuel cells. In general, the AEMs are ionomeric membranes able to conduct hydroxide ions (OH{sup -}) due to the quaternary ammonium groups, which confer high pH equivalent to the AEM. In order to develop alkaline membranes with high chemical and thermal stability, besides satisfactory ionic conductivity for alkaline fuel cells, membranes based on low density polyethylene (LDPE), ultrahigh weight molecular weight polyethylene (UHWHPE), poly(ethylene-co-tetrafluoroethylene) (PETFE) and poly(hexafluoropropylene-co-tetrafluoroethylene) (PFEP) previously irradiated by using {sup 60}Co gamma and electron beam sources, have been synthesized by styrene-grafting, and functionalized with trimethylamine to introduced quaternary ammonium groups. The resulting membranes were characterized by electron paramagnetic resonance (EPR), Raman spectroscopy, thermogravimetry (TG) and electrochemical impedance spectroscopy (EIS). The determination of the grafting degree and water uptake were conducted by gravimetry and ion exchange capacity, by titration. The membranes synthesized with PELD and PEUHMW polymers pre-irradiated at 70 kGy and stored at low temperature (-70 deg C), up to 10 months, showed ionic conductivity results, in hydroxide form (OH{sup -}), of 29 mS.cm{sup -1} and 14 mS.cm{sup -1} at 65 deg C, respectively. The PFEP polymers irradiated by the simultaneous process showed insufficient grating levels for the membrane synthesis, requiring more studies to improve the irradiation and grafting process. The styrene-grafted PETFE membranes, pre-irradiated at 70 kGy and stored at low temperature (-70 deg C), up to 10 months, showed ionic conductivity results, in hydroxide form (OH{sup -}), of 90 mS.cm{sup -1} to 165 mS.cm{sup -1}, in the temperature range 30 to 60 deg C. Such results have demonstrated that LDPE, UHMWPE and PETFE based AEMs are promising

  9. Inhibition of nuclear waste solutions containing multiple aggressive anions

    International Nuclear Information System (INIS)

    Congdon, J.W.

    1987-01-01

    The inhibition of localized corrosion of carbon steel in caustic, high-level radioactive waste solutions was studied using cyclic potentiodynamic polarization scans, supplemented by partially immersed coupon tests. The electrochemical tests provided a rapid and accurate means of determining the relationship between the minimum inhibitor requirements and the concentration of the aggressive anions in this system. Nitrate, sulfate, chloride, and fluoride were identified as aggressive anions, however, no synergistic effects were observed between these anions. This observation may have important theoretical implications because it tends to contradict the behavior of aggressive anions as predicted by existing theories for localized corrosion. 10 refs., 5 figs., 2 tabs

  10. Genotoxicity assessment of membrane concentrates of landfill leachate treated with Fenton reagent and UV-Fenton reagent using human hepatoma cell line.

    Science.gov (United States)

    Wang, Guifang; Lu, Gang; Yin, Pinghe; Zhao, Ling; Yu, Qiming Jimmy

    2016-04-15

    Membrane concentrates of landfill leachates contain organic and inorganic contaminants that could be highly toxic and carcinogenic. In this paper, the genotoxicity of membrane concentrates before and after Fenton and UV-Fenton reagent was assessed. The cytotoxicity and genotoxicity was determined by using the methods of methyltetrazolium (MTT), cytokinesis-block micronucleus (CBMN) and comet assay in human hepatoma cells. MTT assay showed a cytotoxicity of 75% after 24h of exposure to the highest tested concentration of untreated concentrates, and no cytotoxocity for UV-Fenton and Fenton treated concentrates. Both CBMN and comet assays showed increased levels of genotoxicity in cells exposed to untreated concentrates, compared to those occurred in cells exposed to UV-Fenton and Fenton reagent treated concentrates. There was no significant difference between negative control and UV-Fenton treated concentrates for micronucleus and comet assay parameters. UV-Fenton and Fenton treatment, especially the former, were effective methods for degradation of bisphenol A and nonylphenol in concentrates. These findings showed UV-Fenton and Fenton reaction were effective methods for treatment of such complex concentrates, UV-Fenton reagent provided toxicological safety of the treated effluent, and the genotoxicity assays were found to be feasible tools for assessment of toxicity risks of complex concentrates. Copyright © 2016 Elsevier B.V. All rights reserved.

  11. Reversed-phase liquid chromatography coupled on-line with capillary gas chromatography use of an anion-exchange membrane to remove an ion-pair reagent from the eluent.

    NARCIS (Netherlands)

    Brinkman, U.A.T.; Goosens, E.C.; de Jong, D.; de Jong, G.J.; Beerthuizen, I.M.

    1995-01-01

    In order to enable the coupling of reversed-phase liquid chromatography (RPLC) with capillary gas chromatography (GC), the performance of an anion-exchange micromembrane device has been studied to remove the ion-pair reagent methanesulphonic acid from an acetonitrile/water LC eluent. The regenerant

  12. Design and performance evaluation of a microfluidic ion-suppression module for anion-exchange chromatography.

    Science.gov (United States)

    Wouters, Sam; Wouters, Bert; Jespers, Sander; Desmet, Gert; Eghbali, Hamed; Bruggink, Cees; Eeltink, Sebastiaan

    2014-08-15

    A microfluidic membrane suppressor has been constructed to suppress ions of alkaline mobile-phases via an acid-base reaction across a sulfonated poly(tetrafluoroethylene)-based membrane and was evaluated for anion-exchange separations using conductivity detection. The membrane was clamped between two chip substrates, accommodating rectangular microchannels for the eluent and regenerant flow, respectively. Additionally, a clamp-on chip holder has been constructed which allows the alignment and stacking of different chip modules. The response and efficacy of the microfluidic chip suppressor was assessed for a wide range of eluent (KOH) concentrations, using 127 and 183μm thick membranes, while optimizing the flow rate and concentration of the regenerant solution (H2SO4). The optimal operating eluent flow rate was determined at 5μL/min, corresponding to the optimal van-Deemter flow velocity of commercially-available column technology, i.e. a 0.4mm i.d.×250mm long column packed with 7.5μm anion-exchange particles. When equilibrated at 10mM KOH, a 99% decrease in conductivity signal could be obtained within 5min when applying 10mM H2SO4 regenerant at 75μL/min. A background signal as low as 1.2μS/cm was obtained, which equals the performance of a commercially-available electrolytic hollow-fiber suppressor. When increasing the temperature of the membrane suppressor from 15 to 20°C, ion suppression was significantly improved allowing the application of 75mM KOH. The applicability of the chip suppressor has been demonstrated with an isocratic baseline separation of a mixture of seven inorganic ions, yielding plate numbers between 5300 and 10,600 and with a gradient separation of a complex ion mixture. Copyright © 2014 Elsevier B.V. All rights reserved.

  13. The absorption of plutonium by anion resins

    Energy Technology Data Exchange (ETDEWEB)

    Durham, R. W.; Mills, R.

    1961-10-15

    Equilibrium experiments have shown Pu{sup +4} to be absorbed from nitric acid onto an anion resin as a complex anion Pu(NO{sub 3}){sub 6}{sup -2}. The amount of absorption is dependent on the plutonium and nitric acid concentrations in the equilibrium solution with a maximum at 7N to 8N HNO{sub 3}. A low cross-linked resin has a higher capacity and reaches equilibrium more rapidly than the normally supplied resin. Saturation capacity of one per cent cross-linked Nalcite SBR (Dowex 1), 50 -- 100 mesh, is 385 mg Pu/gram dry resin. (author)

  14. Simultaneous determination of free calcium, magnesium, sodium and potassium ion concentrations in simulated milk ultrafiltrate and reconstituted skim milk using the Donnan Membrane Technique

    NARCIS (Netherlands)

    Gao, R.; Temminghoff, E.J.M.; Leeuwen, van H.P.; Valenberg, van H.J.F.; Eisner, M.D.; Boekel, van M.A.J.S.

    2009-01-01

    This study focused on determination of free Ca2+, Mg2+, Na+ and K+ concentrations in a series of CaCl2 solutions, simulated milk ultrafiltrate and reconstituted skim milk using a recently developed Donnan Membrane Technique (DMT). A calcium ion selective electrode was used to compare the DMT

  15. Ultrafiltration Membrane Fouling and the Effect of Ion Exchange Resins

    KAUST Repository

    Jamaly, Sanaa

    2011-12-01

    Membrane fouling is a challenging process for the ultrafiltration membrane during wastewater treatment. This research paper determines the organic character of foulants of different kinds of wastewater before and after adding some ion exchange resins. Two advanced organic characterization methods are compared in terms of concentration of dissolved organic carbons: The liquid chromatography with organic carbon (LC-OCD) and Shimadzu total organic carbon (TOC). In this study, two secondary wastewater effluents were treated using ultrafiltration membrane. To reduce fouling, pretreatment using some adsorbents were used in the study. Six ion exchange resins out of twenty were chosen to compare the effect of adsorbents on fouling membrane. Based on the percent of dissolved organic carbon’s removal, three adsorbents were determined to be the most efficient (DOWEX Marathon 11 anion exchange resin, DOWEX Optipore SD2 polymeric adsorbent, and DOWEX PSR2 anion exchange), and three other ones were determined to the least efficient (DOWEX Marathon A2 anion exchange resin, DOWEX SAR anion exchange resin, and DOWEX Optipore L493 polymeric adsorbent). Organic characterization for feed, permeate, and backwash samples were tested using LC-OCD and TOC to better understand the characteristics of foulants to prevent ultrafiltration membrane fouling. The results suggested that the polymeric ion exchange resin, DOWEX SD2, reduced fouling potential for both treated wastewaters. All the six ion exchange resins removed more humic fraction than other organic fractions in different percent, so this fraction is not the main for cause for UF membrane fouling. The fouling of colloids was tested before and after adding calcium. There is a severe fouling after adding Ca2+ to effluent colloids.

  16. A simple approach to uniform PdAg alloy membranes: Comparative study of conventional and silver concentration-controlled co-plating

    KAUST Repository

    Zeng, Gaofeng

    2014-03-01

    An Ag-controlled co-plating method was developed for the preparation of palladium/silver alloy membranes on porous tubular alumina supports. By controlling the feed rate of Ag to the Pd bath, the concentration of the silver in the plating bath was restricted during the course of plating. As a result, preferential deposition of silver at the beginning was suppressed and uniform dispersion of silver inside the membrane with silver composition in the desired range was achieved. Ultrathin (∼2.5 μm) PdAg alloy membranes with uniform silver composition of ∼25% were successfully obtained. The membrane showed a hydrogen permeance of 0.88 mol m-2 s-1 and pure-gas H2/N2 selectivity of 2140 at 823 K with ΔP = 100 kPa. Only one hydride phase existed in the studied temperature range from 373 to 823 K with ΔPH=100kPa. Direct comparisons with the conventional simply-mixed co-plating method showed that membranes made by the novel Ag-controlled co-plating method had much more uniform silver distribution, smoother surface, denser membrane structure, higher utilization rate of metal sources, and shorter alloying time. © 2013, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.

  17. A simple approach to uniform PdAg alloy membranes: Comparative study of conventional and silver concentration-controlled co-plating

    KAUST Repository

    Zeng, Gaofeng; Shi, Lei; Liu, Yunyang; Zhang, Yanfeng; Sun, Yuhan

    2014-01-01

    An Ag-controlled co-plating method was developed for the preparation of palladium/silver alloy membranes on porous tubular alumina supports. By controlling the feed rate of Ag to the Pd bath, the concentration of the silver in the plating bath was restricted during the course of plating. As a result, preferential deposition of silver at the beginning was suppressed and uniform dispersion of silver inside the membrane with silver composition in the desired range was achieved. Ultrathin (∼2.5 μm) PdAg alloy membranes with uniform silver composition of ∼25% were successfully obtained. The membrane showed a hydrogen permeance of 0.88 mol m-2 s-1 and pure-gas H2/N2 selectivity of 2140 at 823 K with ΔP = 100 kPa. Only one hydride phase existed in the studied temperature range from 373 to 823 K with ΔPH=100kPa. Direct comparisons with the conventional simply-mixed co-plating method showed that membranes made by the novel Ag-controlled co-plating method had much more uniform silver distribution, smoother surface, denser membrane structure, higher utilization rate of metal sources, and shorter alloying time. © 2013, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.

  18. Effect of Diafiltration on Preparation of Fermented Mung Beans Concentrate as Probiotic Savory Flavor Through Ultrafiltration Membrane

    Directory of Open Access Journals (Sweden)

    Aspiyanto Aspiyanto

    2011-05-01

    Full Text Available Diafiltration by means of the ultrafiltration system of probiotic fermented Mung beans (Phaseolus radiatus L. concentrate has been performed to reduce or eliminate salts and smaller impurities than the nominal cut-off of the membrane of 20,000 nominal weight cut-off (NWCO. These processes have been conducted as an attempt in order to get a probiotic product with organoleptic acceptability, composition, and the optimal total lactic acid bacteria (LAB counts because the presence of salts will affect on the viability of LAB and the cell lysis of LAB and limit its utility in food products. Concentrate of probiotic mung beans was prepared through fermentation of LAB using inoculum of LAB consisting of Lactobacillus bulgaricus and Streptococcus thermophylus (1 : 1 on fermented mung beans extract inoculated by inoculum of Rhizopus–C1 in rice substrates at salt condition. Ultrafiltration and diafiltration modes have been carried out at flow rate of 8.77 Liter/minute, room temperature and the pressure of 5 bar (0 to 79.7 minutes and 7 bar (0-154.5 minutes with the ratio of the volume of pure water to the volume of initial feed (number of diavolume, Nd of 0, 0.25, 0.5, 0.75, 1.0 and 1.25, respectively. The experiment results based on total LAB counts as a probiotic product show that a high Nd can reduce the salt content but increase the total LAB counts. Nd of 1.0 results reduce the salt content which is equal to retentate, permeate, and the optimal total LAB counts. Ultrafiltration and diafiltration modes at the pressure of 7 bar and Nd of 1.0 give a retentate with total solid of 6.1355%, salt of 1.3515% and remove 86.15% of the salt from probiotic fermented mung beans concentrate and total LAB counts of 10.73 log cycles. Meanwhile, the permeate obtained at this condition results in flux value of 10.83 Liter/m2.hour with contents of total solid of 6.8199%, salt of 1.325% and total LAB counts of 5.49 log cycles.

  19. Preparation of Organic/Inorganic Siloxane Composite Membranes and Concentration of n-butanol from ABE Solution by Pervaporation

    Energy Technology Data Exchange (ETDEWEB)

    Jee, Ki Yong; Lee, Yong Taek [Kyung Hee University, Yongin (Korea, Republic of)

    2013-10-15

    In this paper, polymer composite membranes and ceramic composite membranes were prepared in order to compare differences in pervaporation performances relative to the support layers. PVDF was used for the polymer support layers, and a-Al{sub 2}O{sub 3} was used for the ceramic support layers. For active layer was coated for PDMS, which is a rubbery polymer. The characterization of membranes were analysed by SEM, contact angle, and XPS. We studied performances relative to the composite membrane support layers in the ABE mixture solutions. The results of the pervaporation, the flux of the ceramic composite membrane was shown to be 250.87 g/m{sup 2}h, which was higher than that of polymer composite membranes, at 195.64 g/m{sup 2}h. However, it was determined that the separation factor of the polymer composite membranes was 31.98 which were higher than that of the ceramic composite membranes, at 20.66.

  20. Comparative techno-economical study between membrane technology systems for obtaining concentrated fertilizers from biogas plant effluents

    DEFF Research Database (Denmark)

    Camilleri Rumbau, Maria Salud; Norddahl, Birgir; Kjærhus Nielsen, Anne

    2013-01-01

    Membrane technology is a promising candidate for producing mineral fertilizers from animal slurry. This paper presents a combination of membrane technologies for processing digested slurry, lists retentions of nitrogen (N), phosphorus (P) and potassium (K) and evaluates the economic and technolog...

  1. Increased anion channel activity is an unavoidable event in ozone-induced programmed cell death.

    Directory of Open Access Journals (Sweden)

    Takashi Kadono

    Full Text Available BACKGROUND: Ozone is a major secondary air pollutant often reaching high concentrations in urban areas under strong daylight, high temperature and stagnant high-pressure systems. Ozone in the troposphere is a pollutant that is harmful to the plant. PRINCIPAL FINDINGS: By exposing cells to a strong pulse of ozonized air, an acute cell death was observed in suspension cells of Arabidopsis thaliana used as a model. We demonstrated that O(3 treatment induced the activation of a plasma membrane anion channel that is an early prerequisite of O(3-induced cell death in A. thaliana. Our data further suggest interplay of anion channel activation with well known plant responses to O(3, Ca(2+ influx and NADPH-oxidase generated reactive oxygen species (ROS in mediating the oxidative cell death. This interplay might be fuelled by several mechanisms in addition to the direct ROS generation by O(3; namely, H(2O(2 generation by salicylic and abscisic acids. Anion channel activation was also shown to promote the accumulation of transcripts encoding vacuolar processing enzymes, a family of proteases previously reported to contribute to the disruption of vacuole integrity observed during programmed cell death. SIGNIFICANCE: Collectively, our data indicate that anion efflux is an early key component of morphological and biochemical events leading to O(3-induced programmed cell death. Because ion channels and more specifically anion channels assume a crucial position in cells, an understanding about the underlying role(s for ion channels in the signalling pathway leading to programmed cell death is a subject that warrants future investigation.

  2. Specific ion effects on membrane potential and the permselectivity of ion exchange membranes.

    Science.gov (United States)

    Geise, Geoffrey M; Cassady, Harrison J; Paul, Donald R; Logan, Bruce E; Hickner, Michael A

    2014-10-21

    Membrane potential and permselectivity are critical parameters for a variety of electrochemically-driven separation and energy technologies. An electric potential is developed when a membrane separates electrolyte solutions of different concentrations, and a permselective membrane allows specific species to be transported while restricting the passage of other species. Ion exchange membranes are commonly used in applications that require advanced ionic electrolytes and span technologies such as alkaline batteries to ammonium bicarbonate reverse electrodialysis, but membranes are often only characterized in sodium chloride solutions. Our goal in this work was to better understand membrane behaviour in aqueous ammonium bicarbonate, which is of interest for closed-loop energy generation processes. Here we characterized the permselectivity of four commercial ion exchange membranes in aqueous solutions of sodium chloride, ammonium chloride, sodium bicarbonate, and ammonium bicarbonate. This stepwise approach, using four different ions in aqueous solution, was used to better understand how these specific ions affect ion transport in ion exchange membranes. Characterization of cation and anion exchange membrane permselectivity, using these ions, is discussed from the perspective of the difference in the physical chemistry of the hydrated ions, along with an accompanying re-derivation and examination of the basic equations that describe membrane potential. In general, permselectivity was highest in sodium chloride and lowest in ammonium bicarbonate solutions, and the nature of both the counter- and co-ions appeared to influence measured permselectivity. The counter-ion type influences the binding affinity between counter-ions and polymer fixed charge groups, and higher binding affinity between fixed charge sites and counter-ions within the membrane decreases the effective membrane charge density. As a result permselectivity decreases. The charge density and polarizability

  3. Specific ion effects on membrane potential and the permselectivity of ion exchange membranes

    KAUST Repository

    Geise, Geoffrey M.

    2014-08-26

    © the Partner Organisations 2014. Membrane potential and permselectivity are critical parameters for a variety of electrochemically-driven separation and energy technologies. An electric potential is developed when a membrane separates electrolyte solutions of different concentrations, and a permselective membrane allows specific species to be transported while restricting the passage of other species. Ion exchange membranes are commonly used in applications that require advanced ionic electrolytes and span technologies such as alkaline batteries to ammonium bicarbonate reverse electrodialysis, but membranes are often only characterized in sodium chloride solutions. Our goal in this work was to better understand membrane behaviour in aqueous ammonium bicarbonate, which is of interest for closed-loop energy generation processes. Here we characterized the permselectivity of four commercial ion exchange membranes in aqueous solutions of sodium chloride, ammonium chloride, sodium bicarbonate, and ammonium bicarbonate. This stepwise approach, using four different ions in aqueous solution, was used to better understand how these specific ions affect ion transport in ion exchange membranes. Characterization of cation and anion exchange membrane permselectivity, using these ions, is discussed from the perspective of the difference in the physical chemistry of the hydrated ions, along with an accompanying re-derivation and examination of the basic equations that describe membrane potential. In general, permselectivity was highest in sodium chloride and lowest in ammonium bicarbonate solutions, and the nature of both the counter- and co-ions appeared to influence measured permselectivity. The counter-ion type influences the binding affinity between counter-ions and polymer fixed charge groups, and higher binding affinity between fixed charge sites and counter-ions within the membrane decreases the effective membrane charge density. As a result permselectivity decreases. The

  4. Supramolecular Chemistry of Selective Anion Recognition for Anions of Environmental Relevance

    International Nuclear Information System (INIS)

    Sessler, Jonathan L.

    2007-01-01

    The major thrust of this project, led by the University of Kansas (Prof. Kristin Bowman-James), entails an exploration of the basic determinants of anion recognition and their application to the design, synthesis, and testing of novel sulfate extractants. A key scientific inspiration for the work comes from the need, codified in simple-to-appreciate terms by the Oak Ridge National Laboratory component of the team (viz. Dr. Bruce Moyer), for chemical entities that can help in the extractive removal of species that have low solubilities in borosilicate glass. Among such species, sulfate anion, has been identified as particularly insidious. Its presence interferes with the vitrification process, thus rendering the remediation of tank waste from, e.g., the Hanford site far more difficult and expensive. The availability of effective extractants, that would allow for the separation of separating sulfate from the major competing anions in the waste, especially nitrate, could allow for pre-vitrification removal of sulfate via liquid-liquid extraction. The efforts at The University of Texas, the subject of this report, have thus concentrated on the development of new sulfate receptors. These systems are designed to increase our basic understanding of anion recognition events and set the stage for the development of viable sulfate anion extractants. In conjunction with the Oak Ridge National Laboratory (ORNL) members of the research team, several of these new receptors were studied as putative extractants, with two of the systems being shown to act as promising synergists for anion exchange.

  5. Influence of aminosilane precursor concentration on physicochemical properties of composite Nafion membranes for vanadium redox flow battery applications

    Science.gov (United States)

    Kondratenko, Mikhail S.; Karpushkin, Evgeny A.; Gvozdik, Nataliya A.; Gallyamov, Marat O.; Stevenson, Keith J.; Sergeyev, Vladimir G.

    2017-02-01

    A series of composite proton-exchange membranes have been prepared via sol-gel modification of commercial Nafion membranes with [N-(2-aminoethyl)-3-aminopropyl]trimethoxysilane. The structure and physico-chemical properties (water uptake, ion-exchange capacity, vanadyl ion permeability, and proton conductivity) of the prepared composite membranes have been studied as a function of the precursor loading (degree of the membrane modification). If the amount of the precursor is below 0.4/1 M ratio of the amino groups of the precursor to the sulfonic groups of Nafion, the composite membranes exhibit decreased vanadium ion permeability while having relatively high proton conductivity. With respect to the use of a non-modified Nafion membrane, the performance of the composite membrane with an optimum precursor loading in a single-cell vanadium redox flow battery demonstrates enhanced energy efficiency in 20-80 mA cm-2 current density range. The maximum efficiency increase of 8% is observed at low current densities.

  6. Study of Aging ion exchange membranes used in separation processes

    International Nuclear Information System (INIS)

    Bellakhal, N.; Ghalloussi, R.; Dammak, L.

    2009-01-01

    Presently, the most important application of ion exchange membranes (IEM) is the electrodialysis. This technique consists of a membrane separation using a series of anion exchange membranes alternately and cations, often used for the desalination of brackish water. These membranes are confronted with problems of aging. Indeed, the more they are used more physical and chemical properties will change. A comparative study of the behavior of both EMI and new but the same treatment is carried out by measuring a magnitude transfer characteristic: ion permeability. Ionic permeability is a physical quantity can have an idea about the selectivity of the membrane towards the charged species and the p orosity o f the membrane. It is a transport of ions (cations + anions) through the membrane. Thus, determining the ion permeability is to determine the diffusion flux of a strong electrolyte through a membrane separating two compartments (one containing electrolytes and other water initially ultrapure who will gradually electrolyte through the membrane). The measurement technique used is that by conductimetric detection because of the ease of its implementation and its accuracy. Thus, the variation of the concentration of the electrolyte is continuously monitored by measuring the conductivity of the solution diluted with time. The curves s = f (t) MEA and MEC new and used varying concentration of the electrolyte membranes show that let in less waste of strong electrolyte (NaCl and HCl) than new ones. This can be explained by: - The functional sites are combined with polyvalent ions present even in trace amounts in the solution process and become inactive. The membrane loses its hydrophilic character and turns into a film almost hydrophobic. - The chemical attacks and electrodialysis operations have degraded and eliminated much of the fixed sites leading to the same effects on the hydrophilic membrane. - These two assumptions have been reinforced by the extent of exchange

  7. Evaluation of the Semipermeable Membrane Device (SPMD) as a Passive In Situ Concentrator of Military Chemicals in Water

    National Research Council Canada - National Science Library

    Petty, Jim

    1995-01-01

    .... This fact, that of membrane permeation as the rate controlling step in the uptake of contaminants, provides SPMD sampling rates, independent of water velocity and is extremely important in developing...

  8. Fouling behavior of poly(ether)sulfone ultrafiltration membrane during concentration of whey proteins: Effect of hydrophilic modification using atmospheric pressure argon jet plasma.

    Science.gov (United States)

    Damar Huner, Irem; Gulec, Haci Ali

    2017-12-01

    The aim of the study was to investigate the effects of hydrophilic surface modification via atmospheric pressure jet plasma (ApJPls) on the fouling propensity of polyethersulfone (PES) ultrafiltration (UF) membranes during concentration of whey proteins. The distance from nozzle to substrate surface of 30mm and the exposure period of 5 times were determined as the most effective parameters enabling an increase in ΔG iwi value of the plain membrane from (-) 14.92±0.89mJ/m 2 to (+) 17.57±0.67mJ/m 2 . Maximum hydrophilicity and minimum surface roughness achieved by argon plasma action resulted in better antifouling behavior, while the hydraulic permeability and the initial permeate flux were decreased sharply due to the plasma-induced surface cross-linking. A quite steady state flux was obtained throughout the UF with the ApJPls modified PES membrane. The contribution of R frev to R t , which was 94% for the UF through the plain membrane, decreased to 43% after the plasma treatment. The overall results of this study highlighted the ApJPls modification decreased the fouling propensity of PES membrane without affecting the original protein rejection capability and improved the recovery of initial permeate flux after chemical cleaning. Copyright © 2017 Elsevier B.V. All rights reserved.

  9. Selective decontamination of cesium and strontium from evaporation concentrates of spent fuel reprocessing plants with crown ethers by transport through supported liquid membranes

    International Nuclear Information System (INIS)

    Casas i Garcia, J.

    1993-01-01

    Reprocessing operations lead to the production of radioactive medium activity liquid waste which is treated by evaporation and solutions of very high salinity are thus formed. The concentrates from reprocessing plant evaporators have to be stored in geological storage sites in view of their strong caesium, strontium and actinides activity. These elements, contained in acid and high sodium nitrate content liquid waste, are removed by means of selective extractants, using the supported liquid membrane technique (SLM), which allows them to be stored in surface sites, the actinides and long-life fission products being respectively recycled and concentrated into reduced volumes. The removal of the actinides is done by means of an Octyl N.N Diisobutyl Carbamoyl Methyl Phosphine Oxide (C.M.P.O.) based liquid membrane, whereas the removal of the caesium and strontium involves crown ethers. Supported liquid membranes (S.L.M.s) have the advantage of implementing very small quantities of extractant, but they generally have poor stability. The extractant, the diluent and the phase modifier impregnating the membrane play a vital role in SLM stability; the support also affects stability by its nature and geometry. For the extraction of strontium, the most lipophilic extractant, DtBu 18 C 6, enables higher strontium transfer kinetics to be attained. As regards caesium, the extremely lipophilic nDec B21 C7 is the most efficient. Caesium cannot be quantitatively removed, due to the competition of the very high content of sodium ions in the concentrate. Stable membranes are obtained with DC18 C6 or DtBu18 C6 diluted in alkylbenzenes with an added phase modifier such as decanol or especially isotridecanol

  10. Selective decontamination for cesium and strontium in evaporation concentrates from reprocessing plants with crown ethers by transport through supported liquid membranes

    International Nuclear Information System (INIS)

    Casas i Garcia, J.

    1991-01-01

    Reprocessing operations lead to the production of radioactive medium activity liquid waste which is treated by evaporation. The concentrates from reprocessing plant evaporators have to be stored in geological storage sites in view of their strong caesium, strontium and actinides activity. These elements, contained in acid and high sodium nitrate content liquid waste, are removed by means of selective extractants, using the supported liquid membrane technique (SLM), which allows them to be stored in surface sites, the actinides and long-life fission products being respectively recycled and concentrated into reduced volumes. The removal of the actinides is done by means of an Octyl N.N Diisobutyl Carbamoyl Methyl Phosphine Oxyde (C.M.P.O.) based liquid membrane, whereas the removal of the caesium and strontium involves crown ethers. Supported liquid membranes (S.L.M.s) have the advantage of implementing very small quantities of extractant, but, they generally have poor stability. The extractant, the diluent and the phase modifier that constitute the organic phase impregnating the membrane play a vital role in SLM stability; the support also affects stability by its nature and geometry. For the extraction of strontium, DtBu 18 C6 enables higher strontium transfer kinetics to be attained than with DC18 C6. As regards caesium, nDec B21 C7 is the most efficient. Unlike strontium, caesium cannot be quantitatively removed, due to the competition of sodium ions in the concentrate. Stable membranes are obtained with DC18 C6 or DtBu18 C6 diluted in alkylbenzene with an added phase modifier such as decanol or isotridecanol. The highest strontium transfer kinetics were obtained with the DC18 C6/hexylbenzene/isotridecanol mixture

  11. Interaction Free Energies of Eight Sodium Salts and a Phosphatidylcholine Membrane

    DEFF Research Database (Denmark)

    Wang, C. H.; Ge, Y.; Mortensen, J.

    2011-01-01

    Many recent reports have discussed specific effects of anions on the properties of lipid membranes and possible roles of such effects within biochemistry. One key parameter in both theoretical and experimental treatments of membrane-salt interactions is the net affinity, that is, the free energy...... salts by dialysis equilibrium measurements. This method provides model free thermodynamic data and allows investigations in the dilute concentration range where solution nonideality and perturbation of membrane structure is limited. The transfer free energy of DMPC from water to salt solutions, Delta mu...

  12. Anionic surface binders

    OpenAIRE

    Aljaž-Rožič Mateja; Hočevar Nežka

    2004-01-01

    The MELAMIN Chemical Factory in Kočevje manufactures synthetic resins and binders for the paper industry. Binders based on AKD (alkyl ketene dimer) are produced which are used for binding paper and cardboard in the range of neutral and partially basic pH. Cationic and, lately, anionic binders are mostly used for the bulk binding of paper and board. The possibility of using AKD binders on paper or board surfaces is presented. In this case partially cationic AKD binders may be applied. When opt...

  13. Formation of interstellar anions

    Science.gov (United States)

    Senent, Maria Luisa

    2012-05-01

    Formation of interstellar anions: M.L. Senent. The recent detection of negative charged species in the ISM1 has instigated enthusiasm for anions in the astrophysical community2. Many of these species are new and entail characterization. How they are formed in astrophysical sources is a question of major relevance. The anion presence in ISM was first predicted theoretically on the basis of electron affinities and on the negative linear chain molecular stabilities. Although very early, they were considered in astrochemical models3-4, their discovery is so recent because their abundances seem to be relatively low. These have to be understood in terms of molecular stabilities, reaction probabilities and radiative and collisional excitations. Then, we present our theoretical work on even carbon chains type Cn and CnH (n=2,4,6) focused to the understanding of anion abundances. We use highly correlated ab initio methods. We performed spectroscopic studies of various isomers that can play important roles as intermediates5-8. In previous papers9-10, we compared C2H and C2H- collisional rates responsible for observed line intensities. Actually, we study hydrogen attachment (Cn +H → CnH and Cn- +H → CnH-) and associative detachment processes (Cn- +H → CnH +e-) for 2, 4 and 6 carbon atom chains11. [1] M.C.McCarthy, C.A.Gottlieb, H.Gupta, P.Thaddeus, Astrophys.J, 652, L141 (2006) [2] V.M.Bierbaum, J.Cernicharo, R.Bachiller, eds., 2011, pp 383-389. [3] A. Dalgarno, R.A. Mc Cray, Astrophys.J,, 181, 95 (1973) [4] E. Herbst E., Nature, 289, 656 (1981); [5] H.Massó, M.L.Senent, P.Rosmus, M.Hochlaf, J.Chem.Phys., 124, 234304 (2006) [6] M.L.Senent, M.Hochlaf, Astrophys. J. , 708, 1452(2010) [7] H.Massó, M.L.Senent, J.Phys.Chem.A, 113, 12404 (2009) [8] D. Hammoutene, M.Hochlaf, M.L.Senent, submitted. [9] A. Spielfiedel, N. Feautrier, F. Najar, D. ben Abdallah, F. Dayou, M.L. Senent, F. Lique, Mon.Not.R.Astron.Soc., 421, 1891 (2012) [10] F.Dumouchel, A, Spielfieldel , M

  14. Selective removal of arsenic and monovalent ions from brackish water reverse osmosis concentrate.

    Science.gov (United States)

    Xu, Pei; Capito, Marissa; Cath, Tzahi Y

    2013-09-15

    Concentrate disposal and management is a considerable challenge for the implementation of desalination technologies, especially for inland applications where concentrate disposal options are limited. This study has focused on selective removal of arsenic and monovalent ions from brackish groundwater reverse osmosis (RO) concentrate for beneficial use and safe environmental disposal using in situ and pre-formed hydrous ferric oxides/hydroxides adsorption, and electrodialysis (ED) with monovalent permselective membranes. Coagulation with ferric salts is highly efficient at removing arsenic from RO concentrate to meet a drinking water standard of 10 μg/L. The chemical demand for ferric chloride however is much lower than ferric sulfate as coagulant. An alternative method using ferric sludge from surface water treatment plant is demonstrated as an efficient adsorbent to remove arsenic from RO concentrate, providing a promising low cost, "waste treat waste" approach. The monovalent permselective anion exchange membranes exhibit high selectivity in removing monovalent anions over di- and multi-valent anions. The transport of sulfate and phosphate through the anion exchange membranes was negligible over a broad range of electrical current density. However, the transport of divalent cations such as calcium and magnesium increases through monovalent permselective cation exchange membranes with increasing current density. Higher overall salt concentration reduction is achieved around limiting current density while higher normalized salt removal rate in terms of mass of salt per membrane area and applied energy is attained at lower current density because the energy unitization efficiency decreases at higher current density. Copyright © 2013 Elsevier B.V. All rights reserved.

  15. Membrane with integrated spacer

    NARCIS (Netherlands)

    Balster, J.H.; Stamatialis, Dimitrios; Wessling, Matthias

    2010-01-01

    Many membrane processes are severely influenced by concentration polarisation. Turbulence promoting spacers placed in between the membranes can reduce the diffusional resistance of concentration polarisation by inducing additional mixing. Electrodialysis (ED) used for desalination suffers from

  16. Well-constructed cellulose acetate membranes for forward osmosis: Minimized internal concentration polarization with an ultra-thin selective layer

    KAUST Repository

    Zhang, Sui; Wang, Kaiyu; Chung, Tai Shung Neal; Chen, Hongmin; Jean, Yanching; Amy, Gary L.

    2010-01-01

    polarization (ECP) and ICP, and the St value of the double dense-layer membrane is much smaller than those reported in literatures. Furthermore, the effects of an intermediate immersion into a solvent/water mixed bath prior to complete immersion in water

  17. Ion Transport across Biological Membranes by Carborane-Capped Gold Nanoparticles.

    Science.gov (United States)

    Grzelczak, Marcin P; Danks, Stephen P; Klipp, Robert C; Belic, Domagoj; Zaulet, Adnana; Kunstmann-Olsen, Casper; Bradley, Dan F; Tsukuda, Tatsuya; Viñas, Clara; Teixidor, Francesc; Abramson, Jonathan J; Brust, Mathias

    2017-12-26

    Carborane-capped gold nanoparticles (Au/carborane NPs, 2-3 nm) can act as artificial ion transporters across biological membranes. The particles themselves are large hydrophobic anions that have the ability to disperse in aqueous media and to partition over both sides of a phospholipid bilayer membrane. Their presence therefore causes a membrane potential that is determined by the relative concentrations of particles on each side of the membrane according to the Nernst equation. The particles tend to adsorb to both sides of the membrane and can flip across if changes in membrane potential require their repartitioning. Such changes can be made either with a potentiostat in an electrochemical cell or by competition with another partitioning ion, for example, potassium in the presence of its specific transporter valinomycin. Carborane-capped gold nanoparticles have a ligand shell full of voids, which stem from the packing of near spherical ligands on a near spherical metal core. These voids are normally filled with sodium or potassium ions, and the charge is overcompensated by excess electrons in the metal core. The anionic particles are therefore able to take up and release a certain payload of cations and to adjust their net charge accordingly. It is demonstrated by potential-dependent fluorescence spectroscopy that polarized phospholipid membranes of vesicles can be depolarized by ion transport mediated by the particles. It is also shown that the particles act as alkali-ion-specific transporters across free-standing membranes under potentiostatic control. Magnesium ions are not transported.

  18. The many ways of making anionic clays

    Indian Academy of Sciences (India)

    Together with hydrotalcite-like layered double hydroxides, bivalent and trivalent metal hydroxides and their hydroxy salts are actually anionic clays consisting of positively charged hydroxide layers with anions intercalated in the interlayer region. The anionic clays exhibit anion sorption, anion diffusion and exchange ...

  19. Electrically Driven Ion Separations in Permeable Membranes

    Energy Technology Data Exchange (ETDEWEB)

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

    2017-04-21

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

  20. Dietary Tocotrienol/γ-Cyclodextrin Complex Increases Mitochondrial Membrane Potential and ATP Concentrations in the Brains of Aged Mice

    Directory of Open Access Journals (Sweden)

    Anke Schloesser

    2015-01-01

    Full Text Available Brain aging is accompanied by a decrease in mitochondrial function. In vitro studies suggest that tocotrienols, including γ- and δ-tocotrienol (T3, may exhibit neuroprotective properties. However, little is known about the effect of dietary T3 on mitochondrial function in vivo. In this study, we monitored the effect of a dietary T3/γ-cyclodextrin complex (T3CD on mitochondrial membrane potential and ATP levels in the brain of 21-month-old mice. Mice were fed either a control diet or a diet enriched with T3CD providing 100 mg T3 per kg diet for 6 months. Dietary T3CD significantly increased mitochondrial membrane potential and ATP levels compared to those of controls. The increase in MMP and ATP due to dietary T3CD was accompanied by an increase in the protein levels of the mitochondrial transcription factor A (TFAM. Furthermore, dietary T3CD slightly increased the mRNA levels of superoxide dismutase, γ-glutamyl cysteinyl synthetase, and heme oxygenase 1 in the brain. Overall, the present data suggest that T3CD increases TFAM, mitochondrial membrane potential, and ATP synthesis in the brains of aged mice.

  1. C-terminus-mediated voltage gating of Arabidopsis guard cell anion channel QUAC1.

    Science.gov (United States)

    Mumm, Patrick; Imes, Dennis; Martinoia, Enrico; Al-Rasheid, Khaled A S; Geiger, Dietmar; Marten, Irene; Hedrich, Rainer

    2013-09-01

    Anion transporters in plants play a fundamental role in volume regulation and signaling. Currently, two plasma membrane-located anion channel families—SLAC/SLAH and ALMT—are known. Among the ALMT family, the root-expressed ALuminium-activated Malate Transporter 1 was identified by comparison of aluminum-tolerant and Al(3+)-sensitive wheat cultivars and was subsequently shown to mediate voltage-independent malate currents. In contrast, ALMT12/QUAC1 (QUickly activating Anion Channel1) is expressed in guard cells transporting malate in an Al(3+)-insensitive and highly voltage-dependent manner. So far, no information is available about the structure and mechanism of voltage-dependent gating with the QUAC1 channel protein. Here, we analyzed gating of QUAC1-type currents in the plasma membrane of guard cells and QUAC1-expressing oocytes revealing similar voltage dependencies and activation–deactivation kinetics. In the heterologous expression system, QUAC1 was electrophysiologically characterized at increasing extra- and intracellular malate concentrations. Thereby, malate additively stimulated the voltage-dependent QUAC1 activity. In search of structural determinants of the gating process, we could not identify transmembrane domains common for voltage-sensitive channels. However, site-directed mutations and deletions at the C-terminus of QUAC1 resulted in altered voltage-dependent channel activity. Interestingly, the replacement of a single glutamate residue, which is conserved in ALMT channels from different clades, by an alanine disrupted QUAC1 activity. Together with C- and N-terminal tagging, these results indicate that the cytosolic C-terminus is involved in the voltage-dependent gating mechanism of QUAC1.

  2. Optimum concentration gradient of the electrocatalyst, Nafion® and poly(tetrafluoroethylene) in a membrane-electrode-assembly for enhanced performance of direct methanol fuel cells.

    Science.gov (United States)

    Liu, Jing Hua; Jeon, Min Ku; Lee, Ki Rak; Woo, Seong Ihl

    2010-12-14

    A combinatorial library of membrane-electrode-assemblies (MEAs) which consisted of 27 different compositions was fabricated to optimize the multilayer structure of direct methanol fuel cells. Each spot consisted of three layers of ink and a gradient was generated by employing different concentrations of the three components (Pt catalyst, Nafion® and polytetrafluoroethylene (PTFE)) of each layer. For quick evaluation of the library, a high-throughput optical screening technique was employed for methanol electro-oxidation reaction (MOR) activity. The screening results revealed that gradient layers could lead to higher MOR activity than uniform layers. It was found that the MOR activity was higher when the concentrations of Pt catalyst and Nafion ionomer decreased downward from the top layer to the bottom layer. On the other hand, higher MOR activity was observed when PTFE concentration increased downward from the top to the bottom layer.

  3. Ion-conducting membranes

    Science.gov (United States)

    Masel, Richard I.; Sajjad, Syed Dawar; Gao, Yan; Liu, Zengcai; Chen, Qingmei

    2017-12-26

    An anion-conducting polymeric membrane comprises a terpolymer of styrene, vinylbenzyl-R.sub.s and vinylbenzyl-R.sub.x. R.sub.s is a positively charged cyclic amine group. R.sub.x is at least one constituent selected from the group consisting Cl, OH and a reaction product between an OH or Cl and a species other than a simple amine or a cyclic amine. The total weight of the vinylbenzyl-R.sub.x groups is greater than 0.3% of the total weight of the membrane. In a preferred embodiment, the membrane is a Helper Membrane that increases the faradaic efficiency of an electrochemical cell into which the membrane is incorporated, and also allows product formation at lower voltages than in cells without the Helper Membrane.

  4. Effect of pretreatment and membrane orientation on fluxes for concentration of whey with high foulants by using NH3/CO2 in forward osmosis.

    Science.gov (United States)

    Seker, M; Buyuksari, E; Topcu, S; Babaoglu, D S; Celebi, D; Keskinler, B; Aydiner, C

    2017-11-01

    Usage of forward osmosis membrane in FO mode, in which active and support layers of the membrane were in contact with the feed and the draw solutions respectively, provided higher initial water flux (12L/m 2 h) than the usage of membrane in PRO mode (6L/m 2 h) having opposite orientation but fluxes approached to each other after 4h during concentration of whey with NH 3 /CO 2 as draw salt. High organic and inorganic foulants of whey was considered as reason for observed result in addition to lower solute resistivity. Initial water flux (8,5L/m 2 h) was lower when pre-treatment was applied before forward osmosis process but final flux (4L/m 2 h) was equal flux of non pre-treatment. Reduction of solute resistivity or absence of hydraulic pressure can be reasons for lower initial flux. Detection of organic carbon but absence of lactose in draw solution showed passage of molecules being different than lactose into draw solution. Copyright © 2017 Elsevier Ltd. All rights reserved.

  5. Dual control of low concentration CO poisoning by anode air bleeding of low temperature polymer electrolyte membrane fuel cells

    Science.gov (United States)

    Klages, Merle; Tjønnås, Johannes; Zenith, Federico; Halvorsen, Ivar J.; Scholta, Joachim

    2016-12-01

    Fuel impurities, fed to a polymer electrolyte membrane fuel cell, can affect stack performance by poisoning of catalyst layers. This paper describes the dynamic behaviour of a stack, including state-of-the-art membrane electrode assemblies (MEA) of three different manufacturers, at different operating conditions. The voltage transients of the step responses to CO poisoning as well as air bleed recovery are compared, revealing differences in performance loss: slow poisoning versus fast recovery, incomplete recovery and voltage oscillation. The recorded behaviour is used to develop a model, based on Tafel equation and first order dynamic response, which can be calibrated to each MEA type. Using this model to predict voltage response, a controller is built with the aim of reducing the total amount of air bleed and monitoring upstream stack processes without the need of sensors measuring the poisoning level. Two controllers are implemented in order to show the concept from a heuristic, easy to implement, and a more technical side allowing more detailed analysis of the synthesis. The heuristic algorithm, based on periodic perturbations of the manipulated variable (air-bleed), is validated on a real stack, revealing a stabilized performance without the need of detailed stack properties knowledge.

  6. Phosphazene-promoted anionic polymerization

    KAUST Repository

    Zhao, Junpeng

    2014-01-01

    In the recent surge of metal-free polymerization techniques, phosphazene bases have shown their remarkable potential as organic promoters/catalysts for the anionic polymerization of various types of monomers. By complexation with the counterion (e.g. proton or lithium cation), phosphazene base significantly improve the nucleophilicity of the initiator/chain-end resulting in rapid and usually controlled anionic/quasi-anionic polymerization. In this review, we will introduce the general mechanism, i.e. in situ activation (of initiating sites) and polymerization, and summarize the applications of such a mechanism on macromolecular engineering toward functionalized polymers, block copolymers and complex macromolecular architectures.

  7. Automated electronic tongue based on potentiometric sensors for the determination of a trinary anionic surfactant mixture.

    Science.gov (United States)

    Cortina, Montserrat; Ecker, Christina; Calvo, Daniel; del Valle, Manuel

    2008-01-22

    An automated electronic tongue consisting of an array of potentiometric sensors and an artificial neural network (ANN) has been developed to resolve mixtures of anionic surfactants. The sensor array was formed by five different flow-through sensors for anionic surfactants, based on poly(vinyl chloride) membranes having cross-sensitivity features. Feedforward multilayer neural networks were used to predict surfactant concentrations. As a great amount of information is required for the correct modelling of the sensors response, a sequential injection analysis (SIA) system was used to automatically provide it. Dodecylsulfate (DS(-)), dodecylbenzenesulfonate (DBS(-)) and alpha-alkene sulfonate (ALF(-)) formed the three-analyte study case resolved in this work. Their concentrations varied from 0.2 to 4mM for ALF(-) and DBS(-) and from 0.2 to 5mM for DS(-). Good prediction ability was obtained with correlation coefficients better than 0.933 when the obtained values were compared with those expected for a set of 16 external test samples not used for training.

  8. Snake cytotoxins bind to membranes via interactions with phosphatidylserine head groups of lipids.

    Directory of Open Access Journals (Sweden)

    Anastasia G Konshina

    Full Text Available The major representatives of Elapidae snake venom, cytotoxins (CTs, share similar three-fingered fold and exert diverse range of biological activities against various cell types. CT-induced cell death starts from the membrane recognition process, whose molecular details remain unclear. It is known, however, that the presence of anionic lipids in cell membranes is one of the important factors determining CT-membrane binding. In this work, we therefore investigated specific interactions between one of the most abundant of such lipids, phosphatidylserine (PS, and CT 4 of Naja kaouthia using a combined, experimental and modeling, approach. It was shown that incorporation of PS into zwitterionic liposomes greatly increased the membrane-damaging activity of CT 4 measured by the release of the liposome-entrapped calcein fluorescent dye. The CT-induced leakage rate depends on the PS concentration with a maximum at approximately 20% PS. Interestingly, the effects observed for PS were much more pronounced than those measured for another anionic lipid, sulfatide. To delineate the potential PS binding sites on CT 4 and estimate their relative affinities, a series of computer simulations was performed for the systems containing the head group of PS and different spatial models of CT 4 in aqueous solution and in an implicit membrane. This was done using an original hybrid computational protocol implementing docking, Monte Carlo and molecular dynamics simulations. As a result, at least three putative PS-binding sites with different affinities to PS molecule were delineated. Being located in different parts of the CT molecule, these anion-binding sites can potentially facilitate and modulate the multi-step process of the toxin insertion into lipid bilayers. This feature together with the diverse binding affinities of the sites to a wide variety of anionic targets on the membrane surface appears to be functionally meaningful and may adjust CT action against

  9. Clinical evaluation and induced corneal vascularization study by native and anionic collagen membranes in rabbits corneas Avaliação clínica e estudo da vascularização corneal induzida pelas membranas de colágeno nativo e aniônico em córneas de coelhos

    Directory of Open Access Journals (Sweden)

    Thaís Eliane Binotto

    2009-12-01

    Full Text Available PURPOSE: To evaluate the corneal vascularization (CV and the clinical aspects induced by interlamellar graft with native (NCM and anionic (ACM collagen membranes in rabbits corneas. METHODS: An interlamellar graft with a 0.25 x 0.25 cm NCM (group 1 or ACM (group 2 fragment was performed in the right eye (treated eye. In the left eye, an estromal tunnel was done (control eye. Sixteen rabbits were used, and they were subdivided into two experimental groups of eight animals each. The clinical evaluation was performed at the 1st, 3rd, 7th, 15th and 30th postoperative days. Corneal vascularization analysis was performed after 30 days by the Images Analizator System Leica Qwin-550®. RESULTS: After 7 days, corneal vascularization was observed at about 2.25 ± 0.71 mm (NCM and at about 1.0 ± 1.69 mm (ACM, respectively, from the limbus in direction to the central cornea. After 15 days, CV increased in both groups (5.25 ± 1.03 mm - NCM; 2.0 ± 2.39 mm - ACM and then progressively decreased until day 30 (2.25 ± 2.10 mm - NCM; 0.75 ± 2.12 mm - ACM. The statistical analysis indicated that the averages of the distances from the limb vessels to the grafts observed after 7 and 15 days had not differed statistically (p=0.17, and after 15 and 30 postoperative days had a tendency to differ statistically (p=0.09. The control eyes did not present any changes. CONCLUSION: The interlamellar graft with native and anionic collagen membranes induced corneal vascularization when applied to rabbit corneas, but anionic collagen membrane induced a smaller corneal vascularization when compared to native collagen membrane. Although further studies are required, the results found in this study demonstrated the usefulness of interlamellar graft with native and anionic collagen membranes in keratoplasties. These membranes consists in one more graft option for the surgical treatment of corneal repair in rabbits and others animals, when other forms of medical and surgical

  10. Performance of polyethylene based radiation grafted anion exchange membrane with polystyrene-b-poly (ethylene/butylene)-b-polystyrene based ionomer using NiCo2O4 catalyst for water electrolysis

    Science.gov (United States)

    Gupta, Gaurav; Scott, Keith; Mamlouk, Mohamed

    2018-01-01

    A soluble anion exchange ionomer with high OH- ion conductivity comparable to that of H+ conductivity of Nafion is synthesised by chloromethylation of polystyrene-b-poly (ethylene/butylene)-b-polystyrene (SEBS) and used with NiCo2O4 electro-catalyst for water electrolysis. The ionomer has an ion exchange capacity of 1.9 mmol g-1 and ionic conductivity of 0.14 S cm-2 at 50 °C. The cell voltage at 20 °C at 100 mA cm-2 is 1.77 and 1.72 V in, 0.1 and 1.0 M NaOH, respectively, for an optimum loading of 10 mg cm-2 NiCo2O4. At 10 mg cm-2 NiCo2O4 electrolyser cell performance is at least equal to or superior to that of IrO2 at 2 mg cm-2 with excellent stability over 1 h. When the catalyst is sprayed on the GDL instead of CCM, the performance is further improved to 1.65 V at 100 mA cm-2 at 60 °C & 0.1 M KOH. The limited AEM electrolyser performance when operating with deionised water in comparison to PEM and alkaline electrolyser arises from the sluggish OER in the AEM environment equivalent to pH of 11.5 and the two orders of magnitude lower HER activity with respect to acid medium combined with the high Tafel slope of 120 mV dec-1.

  11. Simultaneous anionic and cationic redox

    Science.gov (United States)

    Jung, Sung-Kyun; Kang, Kisuk

    2017-12-01

    It is challenging to unlock anionic redox activity, accompanied by full utilization of available cationic redox process, to boost capacity of battery cathodes. Now, material design by tuning the metal-oxygen interaction is shown to be a promising solution.

  12. Schlenk Techniques for Anionic Polymerization

    KAUST Repository

    Ratkanthwar, Kedar; Zhao, Junpeng; Zhang, Hefeng; Hadjichristidis, Nikolaos; Mays, Jimmy

    2015-01-01

    Anionic polymerization-high vacuum techniques (HVTs) are doubtlessly the most prominent and reliable experimental tools to prepare polymer samples with well-defined and, in many cases, complex macromolecular architectures. Due to the high demands

  13. Ultrafiltration and Nanofiltration Multilayer Membranes Based on Cellulose

    KAUST Repository

    Livazovic, Sara

    2016-06-09

    Membrane processes are considered energy-efficient for water desalination and treatment. However most membranes are based on polymers prepared from fossil petrochemical sources. The development of multilayer membranes for nanofiltration and ultrafiltration, with thin selective layers of naturally available cellulose, has been hampered by the availability of non-aggressive solvents. We propose the manufacture of cellulose membranes based on two approaches: (i) silylation, coating from solutions in tetrahydrofuran, followed by solvent evaporation and cellulose regeneration by acid treatment; (ii) casting from solution in 1-ethyl-3-methylimidazolum acetate ([C2mim]OAc), an ionic liquid, followed by phase inversion in water. In the search for less harsh, greener membrane manufacture, the combination of cellulose and ionic liquid is of high interest. Due to the abundance of OH groups and hydrophilicity, cellulose-based membranes have high permeability and low fouling tendency. Membrane fouling is one of the biggest challenges in membrane industry and technology. Accumulation and deposition of foulants onto the surface reduce membrane efficiency and requires harsh chemical cleaning, therefore increasing the cost of maintenance and replacement. In this work the resistance of cellulose 5 membranes towards model organic foulants such as Suwanee River Humic Acid (SRHA) and crude oil have been investigated. Cellulose membrane was tested in this work for oil-water (o/w) separation and exhibited practically 100 % oil rejection with good flux recovery ratio and membrane resistivity. The influence of anionic, cationic and ionic surfactant as well as pH and crude oil concentration on oil separation was investigated, giving a valuable insight in experimental and operational planning.

  14. Fouling prevention of peptides from a tryptic whey hydrolysate during electromembrane processes by use of monovalent ion permselective membranes

    OpenAIRE

    Persico, Mathieu; Bazinet, Laurent

    2017-01-01

    Peptide adsorption occurring on conventional anion- and cation-exchange membranes is one of the main technological locks in electrodialysis (ED) for hydrolysate demineralization. Hence, the peptide fouling of monovalent anion (MAP) and monovalent cation (MCP) permselective membranes was studied and compared to conventional membranes (AMX-SB and CMX-SB). It appeared that the main peptide sequences responsible for fouling were TPEVDDEALEKFDK, VAGTWY and VLVLDTDYK for both anionic membranes; and...

  15. Evaluation of the Semipermeable Membrane Device (SPMD) as a Passive In Situ Concentrator of Military Organic Chemicals in Water

    National Research Council Canada - National Science Library

    Petty, J

    1997-01-01

    ...., 1 ng/L, 10 ng/L, and 100 ng/L) at water temperatures ranging from I 00C to 260C. The data are indicative of concentration independent sampling rates for the 23 OC pesticides employed in this research...

  16. Recovery of Fermented Spinach (Amaranthus sp. Concentrate Through Ultrafiltration Membrane Process as Source of Folic Acid for Smart Food Formula

    Directory of Open Access Journals (Sweden)

    Aspiyanto Aspiyanto

    2017-11-01

    Full Text Available Fermentation process on spinach (Amaranthus sp. by Kombucha culture was done as an effort to recover naturally folic acid as bioactive components to increase smartness. The experimental activity was done by means of UF membrane (100,000 MWCO fitted in Stirred Ultrafiltration Cell (SUFC at stirrer rotation speed 200 and 400 rpm, room temperature, pressure 20 and 40 Psi for 30 min. Result of experimental activity showed that based on both selectivity and recovery of folic acid, process optimization of UF was reached at stirrer rotation speed 200 rpm and pressure 40 Psi. In the optimum condition, SUFC technique was able to recover folic acid in retentate 67.75% and in permeate 97.27% (63.19 µg/mL. Identification of monomer in permeate from the optimum process treatment was find out folic acid monomer with molecular weight (MW 441.39 and relative intensity 93% at mass spectra T2.32 between m/z 257–304 and glutamic acids monomer with MW 148.57 and relative intensity 0.22% at mass spectra T2.82 between m/z 415–470. Other dominant monomer were folic acid fraction.

  17. Determination of arsenate and organic arsenic via potentiometric titration of its heteropoly anions.

    Science.gov (United States)

    Metelka, R; Slavíková, S; Vytras, K

    2002-08-16

    Determination of arsenate based on its conversion to molybdoarsenate heteropoly anions followed by potentiometric titration is described. The titration is realized on the ion-pairing principle using cetylpyridinium chloride (or an analogous titrant containing a lipophilic cation), and is monitored by a carbon paste electrode, although other liquid-polymeric membrane-based electrodes can also be used. Calibration plots of the titrant end-point consumption versus concentration of arsenic were constructed and used to evaluate the content of arsenic in aqueous samples. The method could be applied in the analyses of samples with quite low arsenic content (amounts approximately 10 mug As in 50 cm(3) could be titrated). Organic arsenic was determined analogously after the Schöniger combustion of the sample and conversion of its arsenic to arsenate.

  18. Effect of DS Concentration on the PRO Performance Using a 5-Inch Scale Cellulose Triacetate-Based Hollow Fiber Membrane Module

    Directory of Open Access Journals (Sweden)

    Masahiro Yasukawa

    2018-05-01

    Full Text Available In this study, pressure-retarded osmosis (PRO performance of a 5-inch scale cellulose triacetate (CTA-based hollow fiber (HF membrane module was evaluated under a wide range of operating conditions (0.0–6.0 MPa of applied pressure, 0.5–2.0 L/min feed solution (FS inlet flow rate, 1.0–6.0 L/min DS inlet flow rate and 0.1–0.9 M draw solution (DS concentration by using a PRO/reverse osmosis (RO hybrid system. The subsequent RO system for DS regeneration enabled the evaluation of the steady-stated module performance. In the case of pilot-scale module operation, since the DS dilution and the feed solution (FS up-concentration had occurred and was not negligible, unlike the lab-scale experiment, PRO performance strongly depended on operating conditions such as inlet flow rates of both the DS and FS concentration. To compare the module performance with different configurations, we proposed a converted parameter in which a difference of the packing density between the spiral wound (SW and the HF module was fairly considered. In the case of HF configuration, because of high packing density, volumetric-based performance was higher than that of SW module, that is, the required number of the module would be less than that of SW module in a full-scale PRO plant.

  19. Umbilical cord blood and maternal visfatin (PBEF/NAMPT) concentrations in preterm birth with and without preterm premature rupture of membranes.

    Science.gov (United States)

    Pavlová, Tereza; Zlámal, Filip; Šplíchal, Zbyněk; Tomandl, Josef; Hodická, Zuzana; Ventruba, Pavel; Bienertová-Vašků, Julie

    2018-07-01

    The aim of the study is to investigate differences in visfatin concentrations between mothers with term and preterm birth (PTB) and between mothers who delivered within seven days and after more than seven days following admission for PTB/preterm premature rupture of membranes (PPROMs). Maternal peripheral blood and cord blood were collected from 56 mothers with PTB (31 with PPROM) and 71 mothers with term delivery (three with PPROM). Maternal visfatin concentration was significantly higher for given gestational age in PTBs compared to term deliveries (p = .021) and also in mothers who delivered within seven days after admission for PTB or PPROM, compared to those who delivered after more than seven days (p = .027; p = .039). Cord blood visfatin concentration was found to be decreased in preterm compared to term infants (p = .007). Visfatin in both maternal and fetal circulation may play an important role in the pathogenesis of PTB/PPROM and could be used to distinguish between women who will deliver in a short period of time after clinical presentation of PTB/PPROM and those who deliver later. Nevertheless, additional research is necessary in order to identify its direct involvement in PTB/PPROM.

  20. Automated dual capillary electrophoresis system with hydrodynamic injection for the concurrent determination of cations and anions

    Energy Technology Data Exchange (ETDEWEB)

    Pham, Thi Thanh Thuy; Mai, Thanh Duc [University of Basel, Department of Chemistry, Spitalstrasse 51, Basel 4056 (Switzerland); Centre for Environmental Technology and Sustainable Development (CETASD), Hanoi University of Science, Nguyen Trai Street 334, Hanoi (Viet Nam); Nguyen, Thanh Dam [Centre for Environmental Technology and Sustainable Development (CETASD), Hanoi University of Science, Nguyen Trai Street 334, Hanoi (Viet Nam); Sáiz, Jorge [Department of Analytical Chemistry, Physical Chemistry and Chemical Engineering – University of Alcalá, Ctra. Madrid-Barcelona km 33.6, Alcalá de Henares, Madrid 28871 (Spain); Pham, Hung Viet, E-mail: phamhungviet@hus.edu.vn [Centre for Environmental Technology and Sustainable Development (CETASD), Hanoi University of Science, Nguyen Trai Street 334, Hanoi (Viet Nam); Hauser, Peter C., E-mail: Peter.Hauser@unibas.ch [University of Basel, Department of Chemistry, Spitalstrasse 51, Basel 4056 (Switzerland)

    2014-09-02

    Highlights: • Concurrent determination of cations and anions was carried out by electrophoretic separation. • Optimized conditions for each class of analystes was possible by using separate capillaries. • Simultaneous hydrodynamic injection was carried out. • Pneumatic actuation was used for flushing and sample handling. • The denitrification of drinking water was successfully demonstrated. - Abstract: The capillary electrophoresis instrument developed for the concurrent determination of cations and anions features two separate capillaries and individual detectors to allow independent optimization for each group of ions. The capillaries are joined in a common injector block. The sample is drawn into the injector with a small membrane pump and automated simultaneous injection into both capillaries is achieved by pressurization of the fluid with compressed air. Flushing of the injector and of the capillaries with the background electrolyte is also carried out automatically by the same means. The buffer consisted of 12 mM histidine and 2 mM 18-crown-6 adjusted to pH 4 with acetic acid and was suitable for the contactless conductivity detection employed. The system was optimized for the determination of cationic NH{sub 4}{sup +} and anionic NO{sub 3}{sup −} and NO{sub 2}{sup −}, and linear calibration curves from about 20 μM up to about 1.5 mM were obtained for these ions. In a test run over 8 h, the reproducibility for the peak areas was within ±7%. For demonstration, the instrument was successfully applied to the concurrent monitoring of the concentrations of the three ions during the biological removal of ammonium from contaminated groundwater in a sequencing batch reactor, where NO{sub 3}{sup −} and NO{sub 2}{sup −} are formed as intermediate products.

  1. Spectrophotometric Analysis of Phosphoric Acid Leakage in High-Temperature Phosphoric Acid-Doped Polybenzimidazole Membrane Fuel Cell Application

    Directory of Open Access Journals (Sweden)

    Seungyoon Han

    2016-01-01

    Full Text Available High-temperature proton exchange membrane fuel cells (HT-PEMFCs utilize a phosphoric acid- (PA- doped polybenzimidazole (PBI membrane as a polymer electrolyte. The PA concentration in the membrane can affect fuel cell performance, as a significant amount of PA can leak from the membrane electrode assembly (MEA by dissolution in discharged water, which is a byproduct of cell operation. Spectrophotometric analysis of PA leakage in PA-doped polybenzimidazole membrane fuel cells is described here. This spectrophotometric analysis is based on measurement of absorption of an ion pair formed by phosphomolybdic anions and the cationoid color reagent. Different color reagents were tested based on PA detection sensitivity, stability of the formed color, and accuracy with respect to the amount of PA measured. This method allows for nondestructive analysis and monitoring of PA leakage during HT-PEMFCs operation.

  2. Impact of the antimicrobial peptide Novicidin on membrane structure and integrity

    DEFF Research Database (Denmark)

    Nielsen, Søren B; Otzen, Daniel Erik

    2010-01-01

    We have studied the impact of an 18-residue cationic antimicrobial peptide Novicidin (Nc) on the structure and integrity of partially anionic lipid membranes using oriented circular dichroism (OCD), quartz crystal microbalance with dissipation (QCM-D), dual polarization interferometry (DPI......), calcein dye leakage and fluorescence spectroscopy. OCD consistently showed that Nc is bound in an alpha-helical, surface bound state over a range of peptide to lipid (P/L) ratios up to approximately 1:15. Realignment of Nc at higher P/L ratios correlates to loss of membrane integrity as shown by Laurdan...... concentration, probably through formation of transient pores or transient disruption of the membrane integrity, followed by more extensive membrane disintegration at higher P/L ratios....

  3. Probing lipid membrane electrostatics

    Science.gov (United States)

    Yang, Yi

    The electrostatic properties of lipid bilayer membranes play a significant role in many biological processes. Atomic force microscopy (AFM) is highly sensitive to membrane surface potential in electrolyte solutions. With fully characterized probe tips, AFM can perform quantitative electrostatic analysis of lipid membranes. Electrostatic interactions between Silicon nitride probes and supported zwitterionic dioleoylphosphatidylcholine (DOPC) bilayer with a variable fraction of anionic dioleoylphosphatidylserine (DOPS) were measured by AFM. Classical Gouy-Chapman theory was used to model the membrane electrostatics. The nonlinear Poisson-Boltzmann equation was numerically solved with finite element method to provide the potential distribution around the AFM tips. Theoretical tip-sample electrostatic interactions were calculated with the surface integral of both Maxwell and osmotic stress tensors on tip surface. The measured forces were interpreted with theoretical forces and the resulting surface charge densities of the membrane surfaces were in quantitative agreement with the Gouy-Chapman-Stern model of membrane charge regulation. It was demonstrated that the AFM can quantitatively detect membrane surface potential at a separation of several screening lengths, and that the AFM probe only perturbs the membrane surface potential by external field created by the internai membrane dipole moment. The analysis yields a dipole moment of 1.5 Debye per lipid with a dipole potential of +275 mV for supported DOPC membranes. This new ability to quantitatively measure the membrane dipole density in a noninvasive manner will be useful in identifying the biological effects of the dipole potential. Finally, heterogeneous model membranes were studied with fluid electric force microscopy (FEFM). Electrostatic mapping was demonstrated with 50 nm resolution. The capabilities of quantitative electrostatic measurement and lateral charge density mapping make AFM a unique and powerful

  4. Effect of biocides and anionic homopolymeric inhibitors on the ...

    African Journals Online (AJOL)

    This paper describes the effect of biocides and of the anionic homopolymeric inhibitors on the precipitation behavior of calcium fluoride (CaF2).The efficiency of inhibitors in the presence and absence of biocides was calculated using the half-life (t1/2) approach, where 50% of the concentration has been precipitated.

  5. The Determination of Anionic Surfactants in Natural and Waste Waters.

    Science.gov (United States)

    Crisp, P. T.; And Others

    1983-01-01

    Background information, procedures, and results of an experiment suitable for measuring subpart per million concentrations of anionic surfactants in natural waters and waste effluents are provided. The experiment required only a spectrophotometer or filter photometer and has been successfully performed by students in an undergraduate environmental…

  6. Evaluation of indigenous anion exchange resins for plutonium purification

    International Nuclear Information System (INIS)

    Kumaresan, R.; Sabharwal, K.N.; Srinivasan, T.G.; Vasudeva Rao, P.R.; Thite, B.S.; Ajithlal, R.T.; Sinalkar, Nitin; Dharampurikar, G.R.; Janardhanan, C.; Michael, K.M.; Vijayan, K.; Jambunathan, U.; Dey, P.K.

    2004-01-01

    Preliminary data with pure plutonium nitrate solution indicate that indigenous anion exchange resin can be used for the purification and concentration of plutonium. However, further studies are required to be conducted on larger scale with actual plant feed solutions before arriving to final conclusions. This includes repeated loading and elution cycles studies with the same bed and evaluation of the performance after each cycle

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

    Directory of Open Access Journals (Sweden)

    Pavlović Ksenija

    2015-01-01

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

  8. Ionic liquids comprising heteraromatic anions

    Energy Technology Data Exchange (ETDEWEB)

    Schneider, William F.; Brennecke, Joan F.; Maginn, Edward J.; Mindrup, Elaine; Gurkan, Burcu; Price, Erica; Goodrich, Brett

    2018-04-24

    Some embodiments described herein relate to ionic liquids comprising an anion of a heteraromatic compound such as optionally substituted pyrrolide, optionally substituted pyrazolide, optionally substituted indolide, optionally substituted phospholide, or optionally substituted imidazolide. Methods and devices for gas separation or gas absorption related to these ionic liquids are also described herein.

  9. Quantum mechanics of toroidal anions

    International Nuclear Information System (INIS)

    Afanas'ev, G.N.

    1990-01-01

    We consider a toroidal solenoid with an electric charge attached to it. It turns out that statistical properties of the wave function describing interacting toroidal anions depend on both their relative position and orientation. The influence of the particular gauge choice on the exchange properties of the wave function is studied. 30 refs.; 6 figs

  10. Micellar casein concentrate production with a 3X, 3-stage, uniform transmembrane pressure ceramic membrane process at 50°C.

    Science.gov (United States)

    Hurt, E; Zulewska, J; Newbold, M; Barbano, D M

    2010-12-01

    The production of serum protein (SP) and micellar casein from skim milk can be accomplished using microfiltration (MF). Potential commercial applications exist for both SP and micellar casein. Our research objective was to determine the total SP removal and SP removal for each stage, and the composition of retentates and permeates, for a 3×, continuous bleed-and-feed, 3-stage, uniform transmembrane pressure (UTP) system with 0.1-μm ceramic membranes, when processing pasteurized skim milk at 50°C with 2 stages of water diafiltration. For each of 4 replicates, about 1,100 kg of skim milk was pasteurized (72°C, 16s) and processed at 3× through the UTP MF system. Retentate from stage 1 was cooled to <4°C and stored until the next processing day, when it was diluted with reverse osmosis water back to a 1× concentration and again processed through the MF system (stage 2) to a 3× concentration. The retentate from stage 2 was stored at <4°C, and, on the next processing day, was diluted with reverse osmosis water back to a 1× concentration, before running through the MF system at 3× for a total of 3 stages. The retentate and permeate from each stage were analyzed for total nitrogen, noncasein nitrogen, and nonprotein nitrogen using Kjeldahl methods; sodium dodecyl sulfate-PAGE analysis was also performed on the retentates from each stage. Theoretically, a 3-stage, 3× MF process could remove 97% of the SP from skim milk, with a cumulative SP removal of 68 and 90% after the first and second stages, respectively. The cumulative SP removal using a 3-stage, 3× MF process with a UTP system with 0.01-μm ceramic membranes in this experiment was 64.8 ± 0.8, 87.8 ± 1.6, and 98.3 ± 2.3% for the first, second, and third stages, respectively, when calculated using the mass of SP removed in the permeate of each stage. Various methods of calculation of SP removal were evaluated. Given the analytical limitations in the various methods for measuring SP removal, calculation

  11. Determinação de eletrólitos, gases sanguíneos, osmolalidade, hematócrito, hemoglobina, base titulável e anion gap no sangue venoso de equinos destreinados submetidos a exercício máximo e submáximo em esteira rolante Determination of electrolytes, hemogasometry, osmalility, hematocrit, hemoglobin, base concentration, and anion gap in detrained equines submitted a maximum and submaximum exercise on treadmill

    Directory of Open Access Journals (Sweden)

    M.A.G. Silva

    2009-10-01

    Full Text Available Estudaram-se as alterações nos eletrólitos, nos gases sanguíneos, na osmolalidade, no hematócrito, na hemoglobina, nas bases tituláveis e no anion gap no sangue venoso de 11 equinos da raça Puro Sangue Árabe, destreinados, submetidos a exercício máximo e submáximo em esteira rolante. Esses animais passaram por período de três dias de adaptação à esteira rolante e posteriormente realizaram dois exercícios testes, um de curta e outro de longa duração. Foram coletadas amostras de sangue venoso antes, imediatamente após e 30 minutos após o término dos exercícios. Após a realização do exercício máximo, observou-se diminuição significativa no pHv, na PvCO2, no HCO3, na cBase além de elevação no AG. Detectou-se também aumento do K+, do Ht e da Hb. Ao final do exercício submáximo, constatou-se somente aumento significativo no pHv, na cBase, na SatvO2 e na PvO2. Conclui-se que os equinos submetidos a exercício máximo desenvolveram acidose metabólica e alcalose respiratória compensatória, hipercalemia e aumento nos valores de hematócrito e hemoglobina. No exercício submáximo, os animais apresentaram alcalose metabólica hipoclorêmica e não ocorreram alterações no equilíbrio hidroeletrolítico.Changes in electrolytes, blood gas, osmolality, hematocrit, hemoglobin, base concentration, and anion gap in 11 detrained Arabian horses during exercise on a high-speed treadmill were investigated. After a period of three days of adaptation on the rolling mat, the animals were submitted to two exercises: one of short (maximum and other of long duration (submaximum. Venous blood samples were obtained right before, and 30 minutes after the exercise. After the maximum exercise, it was observed a significative decrease in pHv, PvCO2, HCO3, and cBase and an increase in AG. It was also observed hypercalemia and increase in Ht and Hb. At the final of the submaximum exercise, it was observed significative increase in pH, c

  12. A role for the organic anion transporter OAT3 in renal creatinine secretion in mice

    Science.gov (United States)

    Eraly, Satish A.; Rao, Satish Ramachandra; Gerasimova, Maria; Rose, Michael; Nagle, Megha; Anzai, Naohiko; Smith, Travis; Sharma, Kumar; Nigam, Sanjay K.; Rieg, Timo

    2012-01-01

    Tubular secretion of the organic cation, creatinine, limits its value as a marker of glomerular filtration rate (GFR) but the molecular determinants of this pathway are unclear. The organic anion transporters, OAT1 and OAT3, are expressed on the basolateral membrane of the proximal tubule and transport organic anions but also neutral compounds and cations. Here, we demonstrate specific uptake of creatinine into mouse mOat1- and mOat3-microinjected Xenopus laevis oocytes at a concentration of 10 μM (i.e., similar to physiological plasma levels), which was inhibited by both probenecid and cimetidine, prototypical competitive inhibitors of organic anion and cation transporters, respectively. Renal creatinine clearance was consistently greater than inulin clearance (as a measure of GFR) in wild-type (WT) mice but not in mice lacking OAT1 (Oat1−/−) and OAT3 (Oat3−/−). WT mice presented renal creatinine net secretion (0.23 ± 0.03 μg/min) which represented 45 ± 6% of total renal creatinine excretion. Mean values for renal creatinine net secretion and renal creatinine secretion fraction were not different from zero in Oat1−/− (−0.03 ± 0.10 μg/min; −3 ± 18%) and Oat3−/− (0.01 ± 0.06 μg/min; −6 ± 19%), with greater variability in Oat1−/−. Expression of OAT3 protein in the renal membranes of Oat1−/− mice was reduced to ∼6% of WT levels, and that of OAT1 in Oat3−/− mice to ∼60%, possibly as a consequence of the genes for Oat1 and Oat3 having adjacent chromosomal locations. Plasma creatinine concentrations of Oat3−/− were elevated in clearance studies under anesthesia but not following brief isoflurane anesthesia, indicating that the former condition enhanced the quantitative contribution of OAT3 for renal creatinine secretion. The results are consistent with a contribution of OAT3 and possibly OAT1 to renal creatinine secretion in mice. PMID:22338083

  13. Effects of concentration, temperature and solvent composition on density and apparent molar volume of the binary mixtures of cationic-anionic surfactants in methanol-water mixed solvent media.

    Science.gov (United States)

    Bhattarai, Ajaya; Chatterjee, Sujeet Kumar; Niraula, Tulasi Prasad

    2013-01-01

    The accurate measurements on density of the binary mixtures of cetyltrimethylammonium bromide and sodium dodecyl sulphate in pure water and in methanol(1) + water (2) mixed solvent media containing (0.10, 0.20, and 0.30) volume fractions of methanol at 308.15, 318.15, and 323.15 K are reported. The concentrations are varied from (0.03 to 0.12) mol.l(-1) of sodium dodecyl sulphate in presence of ~ 5.0×10(-4) mol.l(-1) cetyltrimethylammonium bromide. The results showed almost increase in the densities with increasing surfactant mixture concentration, also the densities are found to decrease with increasing temperature over the entire concentration range, investigated in a given mixed solvent medium and these values are found to decrease with increasing methanol content in the solvent composition. The concentration dependence of the apparent molar volumes appear to be negligible over the entire concentration range, investigated in a given mixed solvent medium and the apparent molar volumes increase with increasing temperature and are found to decrease with increasing methanol content in the solvent composition.

  14. Enzymatic methylation of band 3 anion transporter in intact human erythrocytes

    International Nuclear Information System (INIS)

    Lou, L.L.; Clarke, S.

    1987-01-01

    Band 3, the anion transport protein of erythrocyte membranes, is a major methyl-accepting substrate of the intracellular erythrocyte protein carboxyl methyltransferase (S-adenosyl-L-methionine: protein-D-aspartate O-methyltransferase; EC 2.1.1.77). The localization of methylation sites in intact cells by analysis of proteolytic fragments indicated that sites were present in the cytoplasmic N-terminal domain as well as the membranous C-terminal portion of the polypeptide. The amino acid residues that serve as carboxyl methylation sites of the erythrocyte anion transporter were also investigated. 3 H-Methylated band 3 was purified from intact erythrocytes incubated with L-[methyl- 3 H]methionine and from trypsinized and lysed erythrocytes incubated with S-adenosyl-L-[methyl- 3 H]methionine. After proteolytic digestion with carboxypeptidase Y, D-aspartic acid beta-[ 3 H]methyl ester was isolated in low yields (9% and 1%, respectively) from each preparation. The bulk of the radioactivity was recovered as [ 3 H]methanol, and the amino acid residue(s) originally associated with these methyl groups could not be determined. No L-aspartic acid beta-[ 3 H]methyl ester or glutamyl gamma-[ 3 H]methyl ester was detected. The formation of D-aspartic acid beta-[ 3 H]methyl esters in this protein in intact cells resulted from protein carboxyl methyltransferase activity since it was inhibited by adenosine and homocysteine thiolactone, which increases the intracellular concentration of the potent product inhibitor S-adenosylhomocysteine, and cycloleucine, which prevents the formation of the substrate S-adenosyl-L-[methyl- 3 H]methionine

  15. Supramolecular Chemistry of Selective Anion Recognition for Anions of Environmental Relevance

    International Nuclear Information System (INIS)

    Moyer, Bruce a.; Bostick, Debra A.; Fowler, Christopher J.; Kang, Hyun-Ah; Ruas, Alexandre; Delmau, Laetitia H.; Haverlock, Tamara J.; Llinares, Jose M.; Hossain, Alamgir; Kang, S. O.; Bowman-James, Kristin; Shriver, James A.; Marquez, Manuel; Sessler, Jonathan L.

    2005-01-01

    The major thrust of this project led by the University of Kansas (Prof. Kristin Bowman-Jones) entails the exploration of the principles of recognition and separation of sulfate by the design, synthesis, and testing of novel sulfate extractants. A key science need for the cleanup of tank wastes at Hanford has been identified in developing methods to separate those bulk waste components that have low solubilities in borosilicate glass. Sulfate has been identified as a particularly difficult and expensive problem in that its concentration in the waste is relatively high, its solubility in glass is especially low, and it interferes with the performance of both vitrification equipment and the glass waste form. The new extractants will be synthesized by the University of Kansas and the University of Texas, Austin. Oak Ridge National Laboratory (ORNL) is subjecting the new extractants to experiments that will determine their properties and effectiveness in separating sulfate from the major competing anions in the waste, especially nitrate. Such experiments will entail primarily liquid-liquid extraction. Current efforts focus on exciting new systems in which the anion receptors act as synergists for anion exchange

  16. Tripodal receptors for cation and anion sensors

    NARCIS (Netherlands)

    Kuswandi, Bambang; Nuriman, [Unknown; Verboom, Willem; Reinhoudt, David

    2006-01-01

    This review discusses different types of artificial tripodal receptors for the selectiverecognition and sensing of cations and anions. Examples on the relationship between structure andselectivity towards cations and anions are described. Furthermore, their applications as potentiometricion sensing

  17. Metamaterial membranes

    International Nuclear Information System (INIS)

    Restrepo-Flórez, Juan Manuel; Maldovan, Martin

    2017-01-01

    We introduce a new class of metamaterial device to achieve separation of compounds by using coordinate transformations and metamaterial theory. By rationally designing the spatial anisotropy for mass diffusion, we simultaneously concentrate different compounds in different spatial locations, leading to separation of mixtures across a metamaterial membrane. The separation of mixtures into their constituent compounds is critically important in biophysics, biomedical, and chemical applications. We present a practical case where a mixture of oxygen and nitrogen diffusing through a polymeric planar matrix is separated. This work opens doors to new paradigms in membrane separations via coordinate transformations and metamaterials by introducing novel properties and unconventional mass diffusion phenomena. (paper)

  18. Meniscus Membranes For Separation

    Science.gov (United States)

    Dye, Robert C.; Jorgensen, Betty; Pesiri, David R.

    2005-09-20

    Gas separation membranes, especially meniscus-shaped membranes for gas separations are disclosed together with the use of such meniscus-shaped membranes for applications such as thermal gas valves, pre-concentration of a gas stream, and selective pre-screening of a gas stream. In addition, a rapid screening system for simultaneously screening polymer materials for effectiveness in gas separation is provided.

  19. Meniscus membranes for separations

    Science.gov (United States)

    Dye, Robert C [Irvine, CA; Jorgensen, Betty [Jemez Springs, NM; Pesiri, David R [Aliso Viejo, CA

    2004-01-27

    Gas separation membranes, especially meniscus-shaped membranes for gas separations are disclosed together with the use of such meniscus-shaped membranes for applications such as thermal gas valves, pre-concentration of a gas stream, and selective pre-screening of a gas stream. In addition, a rapid screening system for simultaneously screening polymer materials for effectiveness in gas separation is provided.

  20. Reactivity of niobium cluster anions with nitrogen and carbon monoxide

    Science.gov (United States)

    Mwakapumba, Joseph; Ervin, Kent M.

    1997-02-01

    Reactions of small niobium cluster anions, Nbn-(n = 2-7), with CO and N2 are investigated using a flow tube reactor (flowing afterglow) apparatus. Carbon monoxide chemisorption on niobium cluster anions occurs with faster reaction rates than nitrogen chemisorption on corresponding cluster sizes. N2 addition to niobium cluster anions is much more size-selective than is CO addition. These general trends follow those reported in the literature for reactions of neutral and cationic niobium clusters with CO and N2. Extensive fragmentation of the clusters is observed upon chemisorption. A small fraction of the larger clusters survive and sequentially add multiple CO or N2 units without fragmentation. However, chemisorption saturation is not reached at the experimentally accessible pressure and reagent concentration ranges. The thermochemistry of the adsorption processes and the nature of the adsorbed species, molecular or dissociated, are discussed.

  1. Vesicle fusion with bilayer lipid membrane controlled by electrostatic interaction

    Directory of Open Access Journals (Sweden)

    Azusa Oshima

    2017-09-01

    Full Text Available The fusion of proteoliposomes is a promising approach for incorporating membrane proteins in artificial lipid membranes. In this study, we employed an electrostatic interaction between vesicles and supported bilayer lipid membranes (s-BLMs to control the fusion process. We combined large unilamellar vesicles (LUVs containing anionic lipids, which we used instead of proteoliposomes, and s-BLMs containing cationic lipids to control electrostatic interaction. Anionic LUVs were never adsorbed or ruptured on the SiO2 substrate with a slight negative charge, and selectively fused with cationic s-BLMs. The LUVs can be fused effectively to the target position. Furthermore, as the vesicle fusion proceeds and some of the positive charges are neutralized, the attractive interaction weakens and finally the vesicle fusion saturates. In other words, we can control the number of LUVs fused with s-BLMs by controlling the concentration of the cationic lipids in the s-BLMs. The fluidity of the s-BLMs after vesicle fusion was confirmed to be sufficiently high. This indicates that the LUVs attached to the s-BLMs were almost completely fused, and there were few intermediate state vesicles in the fusion process. We could control the position and amount of vesicle fusion with the s-BLMs by employing an electrostatic interaction.

  2. Metal-Oxide Film Conversions Involving Large Anions

    International Nuclear Information System (INIS)

    Pretty, S.; Zhang, X.; Shoesmith, D.W.; Wren, J.C.

    2008-01-01

    The main objective of my research is to establish the mechanism and kinetics of metal-oxide film conversions involving large anions (I - , Br - , S 2- ). Within a given group, the anions will provide insight on the effect of anion size on the film conversion, while comparison of Group 6 and Group 7 anions will provide insight on the effect of anion charge. This research has a range of industrial applications, for example, hazardous radioiodine can be immobilized by reaction with Ag to yield AgI. From the perspective of public safety, radioiodine is one of the most important fission products from the uranium fuel because of its large fuel inventory, high volatility, and radiological hazard. Additionally, because of its mobility, the gaseous iodine concentration is a critical parameter for safety assessment and post-accident management. A full kinetic analysis using electrochemical techniques has been performed on the conversion of Ag 2 O to (1) AgI and (2) AgBr. (authors)

  3. Metal-Oxide Film Conversions Involving Large Anions

    Energy Technology Data Exchange (ETDEWEB)

    Pretty, S.; Zhang, X.; Shoesmith, D.W.; Wren, J.C. [The University of Western Ontario, Chemistry Department, 1151 Richmond St., N6A 5B7, London, Ontario (Canada)

    2008-07-01

    The main objective of my research is to establish the mechanism and kinetics of metal-oxide film conversions involving large anions (I{sup -}, Br{sup -}, S{sup 2-}). Within a given group, the anions will provide insight on the effect of anion size on the film conversion, while comparison of Group 6 and Group 7 anions will provide insight on the effect of anion charge. This research has a range of industrial applications, for example, hazardous radioiodine can be immobilized by reaction with Ag to yield AgI. From the perspective of public safety, radioiodine is one of the most important fission products from the uranium fuel because of its large fuel inventory, high volatility, and radiological hazard. Additionally, because of its mobility, the gaseous iodine concentration is a critical parameter for safety assessment and post-accident management. A full kinetic analysis using electrochemical techniques has been performed on the conversion of Ag{sub 2}O to (1) AgI and (2) AgBr. (authors)

  4. Organoboron compounds as Lewis acid receptors of fluoride ions in polymeric membranes.

    Science.gov (United States)

    Jańczyk, Martyna; Adamczyk-Woźniak, Agnieszka; Sporzyński, Andrzej; Wróblewski, Wojciech

    2012-07-06

    Newly synthesized organoboron compounds - 4-octyloxyphenylboronic acid (OPBA) and pinacol ester of 2,4,6-trifluorophenylboronic acid (PE-PBA) - were applied as Lewis acid receptors of fluoride anions. Despite enhanced selectivity, the polymer membrane electrodes containing the lipophilic receptor OPBA exhibited non-Nernstian slopes of the responses toward fluoride ions in acidic conditions. Such behavior was explained by the lability of the B-O bond in the boronic acids, and the OH(-)/F(-) exchange at higher fluoride content in the sample solution. In consequence, the stoichiometry of the OPBA-fluoride complexes in the membrane could vary during the calibration, changing the equilibrium concentration of the primary anion in membrane and providing super-Nernstian responses. The proposed mechanism was supported by (19)F NMR studies, which indicated that the fluoride complexation proceeds more effectively in acidic solution leading mainly to PhBF(3)(-) species. Finally, the performances of the membranes based on the phenylboronic acid pinacol ester, with a more stable B-O bond, were tested. As it was expected, Nernstian fluoride responses were recorded for such membranes with worsened fluoride selectivity. Copyright © 2012 Elsevier B.V. All rights reserved.

  5. Simultaneous anion and cation mobility in polypyrrole

    DEFF Research Database (Denmark)

    Skaarup, Steen; Bay, Lasse; Vidanapathirana, K.

    2003-01-01

    and the expulsion of anions; a broad anodic peak centered at ca. - 0.5 V representing the expulsion of cations; and a second broad peak at +0.2 to +0.5 V corresponding to anions being inserted. Although the motion of cations is the most important, as expected, there is a significant anion contribution, thereby...... complicating reproducibility when employing PPy(DBS) polymers as actuators. When the cation is doubly charged, it enters the film less readily, and anions dominate the mobility. Using a large and bulky cation switches the mechanism to apparently total anion motion. The changes in area of the three peaks...

  6. Supramolecular Chemistry of Environmentally Relevant Anions

    International Nuclear Information System (INIS)

    Bowman-James, Kristin; Moyer, B.A.; Sessler, Jonathan L.

    2003-01-01

    The goal of this project is the development of highly selective extractants for anions targeting important and timely problems of critical interest to the EMSP mission. In particular, sulfate poses a special problem in cleaning up the Hanford waste tanks in that it interferes with vitrification, but available technologies for sulfate removal are limited. The basic chemical aspects of anion receptor design of functional pH independent systems as well as design of separations strategies for selective and efficient removal of targeted anions have been probed. Key findings include: (1) some of the first synthetic sulfate-selective anion-binding agents; (2) simple, structure-based methods for modifying the intrinsic anion selectivity of a given class of anion receptors; and (3) the first system capable of extracting sulfate from acidic, nitrate-containing aqueous media. Receptor design, structural influences on anion binding affinities, and findings from liquid-liquid extraction studies will be discussed

  7. Adsorption of an anionic dispersant on lignite

    Energy Technology Data Exchange (ETDEWEB)

    Yavuz, R.; Kucukbayrak, S. [Istanbul Technical University, Istanbul (Turkey). Dept. of Chemical Engineering, Chemical & Metallurgical Engineering Faculty

    2001-12-01

    Since coal is not a homogeneous substance but a mixture of carbonaceous materials and mineral matter, it has a variety of surface properties. Therefore, it is not easy to control the properties of coal suspensions by simply adjusting variables, such as pH and/or electrolyte. A chemical agent needs to be added to control the properties of the coal suspensions. The adsorption behavior of an anionic dispersant in the presence of a wetting agent using some Turkish lignite samples was investigated. The effects of dispersant concentration, temperature and pH on the dispersant adsorption were studied systematically, and the experimental results are presented. Pellupur B69 as a dispersant, commercial mixture of formaldehyde condensate sodium salt of naphthalene sulphonic acid, and Texapon N{sub 2}5 as a wetting agent, a sodium lauryl ether sulfate, have been used.

  8. Ca(2+-dependent regulation of the Ca(2+ concentration in the myometrium mitochondria. II. Ca(2+ effects on mitochondria membranes polarization and [Ca(2+](m

    Directory of Open Access Journals (Sweden)

    L. G. Babich

    2017-06-01

    Full Text Available It is known that Ca2+ accumulation in the mitochondria undergoes complex regulation by Ca2+ itself. But the mechanisms of such regulation are still discussed. In this paper we have shown that Ca ions directly or indirectly regulate the level of myometrium mitochondria membranes polarization. The additions of 100 µM Ca2+ were accompanied by depolarization of the mitochondria membranes. The following experiments were designed to study the impact of Ca2+ on the myometrium mitochondria [Ca2+]m. Isolated myometrium mitochondria were preincubated without or with 10 μM Са2+ followed by 100 μM Са2+ addition. Experiments were conducted in three mediums: without ATP and Mg2+ (0-medium, in the presence of 3 mM Mg2+ (Mg-medium and 3 mM Mg2+ + 3 mM ATP (Mg,ATP-medium. It was shown that the effects of 10 μM Са2+ addition were different in different mediums, namely in 0- and Mg-medium the [Ca2+]m values increased, whereas in Mg,ATP-medium statistically reliable changes were not registered. Preincubation of mitochondria with 10 μM Са2+ did not affect the [Ca2+]m value after the addition of 100 μM Са2+. The [Ca2+]m values after 100 μM Са2+ addition were the same in 0- and Mg,ATP-mediums and somewhat lower in Mg-medium. Preliminary incubation of mitochondria with 10 μM Са2+ in 0- and Mg-mediums reduced changes of Fluo 4 normalized fluorescence values that were induced by 100 μM Са2+ additions, but in Mg,ATP-medium such differences were not recorded. It is concluded that Са2+ exchange in myometrium mitochondria is regulated by the concentration of Ca ions as in the external medium, so in the matrix of mitochondria. The medium composition had a significant impact on the [Са2+]m values in the absence of exogenous cation. It is suggested that light increase of [Са2+]m before the addition of 100 μM Са2+ may have a positive effect on the functional activity of the mitochondria.

  9. Anion

    Directory of Open Access Journals (Sweden)

    A. Vadivel Murugan

    2003-01-01

    . Its characterization is investigated by Fourier Transform Infrared Spectroscopy (FT-IR and Scanning Electron Microscopy (SEM. The hybrid material presents predominantly high electronic conductivities of around 2.0 and 7.0 S cm-1 at 300 and 400K respectively.

  10. Study of the simultaneous complexation of a cation and of an anion using functionalized calixarenes

    International Nuclear Information System (INIS)

    Moli, Ch.

    2002-03-01

    The chemical reprocessing of irradiated nuclear fuels leads to the production of high-level radioactive liquid wastes which contain long-lived toxic radioelements. In the framework of the long-term management of these wastes, important research work is carried out for the separation of these radioelements for their further transmutation or immobilization inside specific matrices. These radioelements are present in acid solutions of fission products in the form of cations (cesium), anions (technetium, selenium) and molecules (iodine). Crown calixarenes have been successfully used for the extraction of cesium thanks to their exceptional selectivities. This work is mainly based on the use of the chelating properties of calixarenes for the extraction of anionic radioelements. Calixarenes functionalized by amino-carbon chains have been selected. The synthesis of amine calix[4]arenes and calix[6]arenes is described and their extractive and ionophoretic properties with respect to radioelements are shown using aqueous selective separation techniques like the liquid-liquid extraction and the supported liquid membrane transport. Technetium and selenium are extracted by amine calixarenes from a 10 -2 M aqueous solution of nitric acid. At this acidity, no selenium transport is observed, while technetium transport is efficient: the solution is quasi-totally decontaminated in 6 hours. Molecular iodine is efficiently extracted with a simple organic diluent, the 1,2-nitro-phenyl-hexyl-ether, from a strongly concentrated aqueous solution of nitric acid (HNO 3 = 3 M). The transport of iodine becomes faster and more efficient when its concentration in the solution is higher. (J.S.)

  11. Effect of applied voltage and initial concentration to desalting NaCl solution using electrodialysis

    International Nuclear Information System (INIS)

    Boubakri, Ali; Gzara, Lassaad; Dhahbi, Mahmoud; Bouguecha, Salah

    2009-01-01

    The desalination process of electrodialysis is one of membrane separation that competes with reverse osmosis for desalination of brackish water and seawater. In this work water desalination using a laboratory electrodialysis was performed and evaluated to desalting aqueous solutions containing 5000, 10000 and 20000 mg/L NaCl at different applied potential (10, 15 and 20 V) and at a constant flow rate of 3 L/min. Nine electrodialysis runs were performed. The results showed that the increasing of applied potential and decreasing of NaCl concentration have an important effect to enhance the electrodialysis performance. The efficiencies of each experiment were evaluated as function of specific power consumption with the electrical energy consumed in electrodialysis stack. It was obtained that the specific power consumption increased when the salt concentration and applied voltage increased. A laboratory electrodialysis stack containing fifteen cation exchange membranes and fifteen anion exchange membranes of 0,716 m 2 total effective area was used.

  12. Non-Native Metal Ion Reveals the Role of Electrostatics in Synaptotagmin 1-Membrane Interactions.

    Science.gov (United States)

    Katti, Sachin; Nyenhuis, Sarah B; Her, Bin; Srivastava, Atul K; Taylor, Alexander B; Hart, P John; Cafiso, David S; Igumenova, Tatyana I

    2017-06-27

    C2 domains are independently folded modules that often target their host proteins to anionic membranes in a Ca 2+ -dependent manner. In these cases, membrane association is triggered by Ca 2+ binding to the negatively charged loop region of the C2 domain. Here, we used a non-native metal ion, Cd 2+ , in lieu of Ca 2+ to gain insight into the contributions made by long-range Coulombic interactions and direct metal ion-lipid bridging to membrane binding. Using X-ray crystallography, NMR, Förster resonance energy transfer, and vesicle cosedimentation assays, we demonstrate that, although Cd 2+ binds to the loop region of C2A/B domains of synaptotagmin 1 with high affinity, long-range Coulombic interactions are too weak to support membrane binding of individual domains. We attribute this behavior to two factors: the stoichiometry of Cd 2+ binding to the loop regions of the C2A and C2B domains and the impaired ability of Cd 2+ to directly coordinate the lipids. In contrast, electron paramagnetic resonance experiments revealed that Cd 2+ does support membrane binding of the C2 domains in full-length synaptotagmin 1, where the high local lipid concentrations that result from membrane tethering can partially compensate for lack of a full complement of divalent metal ions and specific lipid coordination in Cd 2+ -complexed C2A/B domains. Our data suggest that long-range Coulombic interactions alone can drive the initial association of C2A/B with anionic membranes and that Ca 2+ further augments membrane binding by the formation of metal ion-lipid coordination bonds and additional Ca 2+ ion binding to the C2 domain loop regions.

  13. Phosphoenolpyruvate carboxylase from C4 leaves is selectively targeted for inhibition by anionic phospholipids

    NARCIS (Netherlands)

    Monreal, J.A.; McLoughlin, F.; Echevarría, C.; García-Mauriño, S.; Testerink, C.

    2010-01-01

    Phosphoenolpyruvate carboxylase (PEPC; EC 4.1.1.31) is an enzyme playing a crucial role in photosynthesis of C4 plants. Here, we identify anionic phospholipids as novel regulators that inhibit C4 PEPC activity and provide evidence that the enzyme partially localizes to membranes.

  14. Atomic-scale structure and electrostatics of anionic palmitoyloleoylphosphatidylglycerol lipid bilayers with Na+ counterions

    NARCIS (Netherlands)

    Zhao, W.; Róg, T.; Gurtovenko, A.A.; Vattulainen, I.; Karttunen, M.E.J.

    2007-01-01

    Anionic palmitoyloleoylphosphatidylglycerol (POPG) is one of the most abundant lipids in nature, yet its atomic-scale properties have not received significant attention. Here we report extensive 150-ns molecular dynamics simulations of a pure POPG lipid membrane with sodium counterions. It turns out

  15. Molecular dynamics investigation of the influence of anionic and zwitterionic interfaces on antimicrobial peptides' structure: implications for peptide toxicity and activity

    DEFF Research Database (Denmark)

    Khandelia, Himanshu; Kaznessis, Yiannis N

    2006-01-01

    Molecular dynamics simulations of three related helical antimicrobial peptides have been carried out in zwitterionic diphosphocholine (DPC) micelles and anionic sodiumdodecylsulfate (SDS) micelles. These systems can be considered as model mammalian and bacterial membrane interfaces, respectively...

  16. A single-cell technique for the measurement of membrane potential, membrane conductance, and the efflux of rapidly penetrating solutes in Amphiuma erythrocytes.

    Science.gov (United States)

    Stoner, L C; Kregenow, F M

    1980-10-01

    We describe a single-cell technique for measuring membrane potential, membrane resistance, and the efflux of rapidly penetrating solutes such as Cl and H2O. Erythrocytes from Amphiuma means were aspirated into a Sylgard (Dow Corning Corp.)-coated capillary. The aspirated cell separated a solution within the capillary from a solution in the bath. Each of these two solutions was contiguous with approximately 5% of the total membrane surface. Microelectrodes placed concentrically within the capillary permit the measurement of intracellular voltage, specific membrane resistance, and the electrical seal between the two solutions. The intracellular voltage averaged -17.7 mV (pH 7.6) and changed as either intra- or extracellular chloride was varied. The average specific membrane resistance measured by passing current across the exposed membrane surface was 110 ohm-cm2. 36Cl and tritiated H2O fluxes (0.84 +/- 0.05 x 10(-6) M . cm-2 . min-1 and 6.4 +/- 1.5 x 10(-3) M . cm-2 . min-1, respectively) were determined by noting the rate at which isotope leaves the cell and crosses the membrane exposed to the bath. Our measured values for the flux of 36Cl and tritiated H2O approximate reported values for free-floating cells. 36Cl efflux, in addition, is inhibited by 4-acetamido-4'-isothiocyano-stilbene 2,2'-disulfonic acid (SITS) and furosemide, known inhibitors of the anion exchange mechanism responsible for the rapid anion fluxes of red blood cells. One can also demonstrate directly that > 89% of 36Cl efflux is "electrically silent" by analyzing the flux in the presence of an imposed transcellular voltage.

  17. The Influence of Emulgator on Stability of Emulsion H3PO4 in Topo-Kerosene and Efficiency at Emulsion Membrane Extraction of La and Nd Concentrate Product of Monazite Sand Treatment

    International Nuclear Information System (INIS)

    Purwani, MV.; Bintarti, AN.; Subagiono, R.

    2002-01-01

    The making of La and Nd concentrate from monazite sand have been done. The separation of La and Nd by emulsion 1M H 3 PO 4 in 5 % TOPO-Kerosene membrane extraction. The feed or aqueous phase was La and Nd concentrate in 1M HNO 3 . Emulgator Span-80 and Tween-80 were used to stabilize emulsion membrane. The influence parameters were percentage of Span-80 and ratio of Span-80 and Tween-80. After formation of emulsion membrane, the extraction process was carried out. Ratio of volume of feed : volume membrane phase = 1 : 1, ratio of volume of 5% TOPO - Kerosene : ratio of volume of 1M H 3 PO 4 1 : 1. The best yield were obtained time of emulsification was 10 minutes with the speed of emulsion was 6000 rpm and concentration of span-80 was 5%. At this condition was obtained the extraction efficiency of La was 55.55%, the extraction efficiency of Nd was 41.6% the stripping efficiency of La was 35.05%, the stripping efficiency of Nd was 87.32 %, the total efficiency of La was 19.46%, the total efficiency of Nd was 36.30% and Separation factor of Nd and La = 1.87. (author)

  18. Environmental behavior of inorganic anions

    International Nuclear Information System (INIS)

    Garland, T.R.; Cataldo, D.A.; Fellows, R.J.; Wildung, R.E.

    1987-01-01

    Recent efforts have addressed two aspects of anion behavior in the soil/plant system. The first involves evaluation of the gaseous component of the terrestrial iodine cycle in soils and plants. Field analyses of 129 I in soils and vegetation adjacent to a fuels reprocessing facility, which was idle for 10 years prior to the study, indicated that there may be a significant gaseous component to the terrestrial iodine cycle. Soil substrates, including a silt-sand, organic forest soil, quartz sand, and a sterilized soil, were amended with radioiodide, and the rates and quality of the volatile components evaluated

  19. Effect of reagent charge on the labeling of erythrocyte membrane proteins by photoactivated reagents

    International Nuclear Information System (INIS)

    Schaeffer, J.C.; Hakimian, R.; Shimer, M.L.

    1986-01-01

    Leaky erythrocyte ghosts were labeled with 3 H-[2-(4-azido-2-nitroanilino)ethyl]trimethylammonium iodide (cationic label) or 3 H-N-(4-azido-2-nitrophenyl)-β-alanine (anionic label). After the membranes were thoroughly washed, seven times as much cationic label was associated with the membranes as anionic label at 5 μM, whereas at 50 μM the cationic label was favored 15-fold. The distribution of label in the membrane proteins was ascertain by SDS-gel electrophoresis followed by autoradiography. At 50 μM cationic label, erythrocyte membrane protein bands 1,2,3,4.2, and 5 were intensely labeled, while band 6 was labeled weakly. At 5 μM cationic label, bands 1 and 4.2 were heavily labeled, while 2,3 and 5 were labeled less well. At both 50 μM and 5 μM anionic label, bands 1 and 6 were most prominently labeled. Bands 2,3,4.2 and 5 were labeled also at 50 μM, but they were labeled only very weakly at 5 μM. Band 4.1 was labeled very poorly if at all by either reagent. A mixture of the reagents gave an additive pattern. Thus, the charge and concentration of these reagents appear to play a major role in their ability to label membrane proteins indiscriminately. Because these reagents contain the same chromophore, 4-azido-2-nitroaniline, and differ mainly only in their charge, they may prove useful in assessing the location of charged sites on proteins in supramolecular complexes

  20. Study of CD69 antigen expression and integrity of leukocyte cellular membrane in stored platelet concentrates following irradiation and treatment with Mirasol® PRT System.

    Science.gov (United States)

    Lachert, Elżbieta; Woźniak, Jolanta; Antoniewicz-Papis, Jolanta; Krzywdzińska, Agnieszka; Kubis, Jolanta; Mikołowska, Agata; Letowska, Magdalena

    2017-01-01

    Leukocytes in transfused blood components, particularly residual lymphocytes, have been shown to contribute to the occurrence of various adverse reactions. One of the most severe is transfusionassociated graft versus host disease (TA-GvHD) following transfusion of blood components contaminated with immunocompetent T lymphocytes. Irradiation is a routine method for protection against TA-GvHD. According to the literature, some pathogen reduction methods have also been proven effective for the inactivation of T lymphocytes, and so they may be considered as an alternative to irradiation. Comparison of CD69 antigen expression and the integrity of the leukocyte cellular membrane in stored platelet concentrates (PCs) following irradiation with the Gammacell 3000 Elan (Nordion Inc., Ottawa, Canada) and treatment with the Mirasol® Pathogen Reduction Technology (PRT) System (Terumo BCT, Lakewood, USA). The study included seven experiments. For each experiment we used 3 PCs, for Mirasol® PRT System treatment (M), for Gammacell 3000 Elan irradiation (R), and for the control (C). 7-amino-actinomycin D (7-AAD, Becton Dickinson, Franklin Lakes, USA) permeability was used to determine lymphocyte viability while CD69 antigen expression was the marker of lymphocyte activation. Analyses of 7-AAD and CD69 antigen expression were performed in a FACS Canto I flow cytometer (Becton Dickinson, USA). During 6 storage days, viable lymphocyte count decreased to 28% (p = 0.001) in the Mirasol® PRT System treated PCs and to 65% (p = 0.004) in the irradiated PCs. A statistically significant increase in CD69 expression in the irradiated PCs was observed; 1.3-fold on day 3 and 1.5-fold on day 6. In the Mirasol ® PRT System treated PCs, no statistically significant increase was observed. The in vitro results suggest that the Mirasol® PRT System is as effective as irradiation due to donor leukocyte inactivation capacity.

  1. Effect of Structure on Charge Distribution in the Isatin Anions in Aprotic Environment: Spectral Study

    Directory of Open Access Journals (Sweden)

    Pavol Tisovský

    2017-11-01

    Full Text Available Five isatin anions were prepared by deprotonation of initial isatins in aprotic solvents using basic fluoride and acetate anions (F− and CH3COO−. The F− basicity is sufficient to deprotonate isatin NH hydrogen from all the studied compounds. This process is reversible. In the presence of proton donor solvents, the anions form the corresponding isatins. The isatin hydrogen acidity depends on the overall structure of the isatin derivatives. The anions were characterized by ultraviolet–visible (UV–Vis, Fourier transform infrared (FTIR and nuclear magnetic resonance (NMR spectroscopy. Interestingly, the anions form aggregates at concentrations above 10−3 mol·dm−3. Further, the effect of cations on the UV–Vis spectra of the studied anions was studied. Charge transfer and its distribution in the anion depends on the radius and the cation electron configuration. The alkali metal cations, tetrabutylammonium (TBA+, Mg2+ and Ag+, interact with the C-2 carbonyl oxygen of the isatin anion. The interaction has a coulombic character. On the other hand, Cd2+, Zn2+, Hg2+, Co2+, and Cu+ cations form a coordinate bond with the isatin nitrogen.

  2. Concentration gradient driven molecular dynamics: a new method for simulations of membrane permeation and separation† †Electronic supplementary information (ESI) available: Additional simulation settings, results and snapshots. See DOI: 10.1039/c6sc04978h Click here for additional data file.

    Science.gov (United States)

    Ozcan, Aydin; Perego, Claudio; Salvalaglio, Matteo; Parrinello, Michele

    2017-01-01

    In this study, we introduce a new non-equilibrium molecular dynamics simulation method to perform simulations of concentration driven membrane permeation processes. The methodology is based on the application of a non-conservative bias force controlling the concentration of species at the inlet and outlet of a membrane. We demonstrate our method for pure methane, ethane and ethylene permeation and for ethane/ethylene separation through a flexible ZIF-8 membrane. Results show that a stationary concentration gradient is maintained across the membrane, realistically simulating an out-of-equilibrium diffusive process, and the computed permeabilities and selectivity are in good agreement with experimental results. PMID:28966778

  3. Schlenk Techniques for Anionic Polymerization

    KAUST Repository

    Ratkanthwar, Kedar

    2015-09-01

    Anionic polymerization-high vacuum techniques (HVTs) are doubtlessly the most prominent and reliable experimental tools to prepare polymer samples with well-defined and, in many cases, complex macromolecular architectures. Due to the high demands for time and skilled technical personnel, HVTs are currently used in only a few research laboratories worldwide. Instead, most researchers in this filed are attracted to more facile Schlenk techniques. The basic principle of this technique followed in all laboratories is substantially the same, i.e. the use of alternate vacuum and inert gas atmosphere in glass apparatus for the purification/charging of monomer, solvents, additives, and for the manipulation of air-sensitive compounds such as alkyl metal initiators, organometallic or organic catalysts. However, it is executed quite differently in each research group in terms of the structure of Schlenk apparatus (manifolds, connections, purification/storage flasks, reactors, etc.), the use of small supplementary devices (soft tubing, cannulas, stopcocks, etc.) and experimental procedures. The operational methods are partly purpose-oriented while also featured by a high flexibility, which makes it impossible to describe in detail each specific one. In this chapter we will briefly exemplify the application of Schlenk techniques for anionic polymerization by describing the performance of a few experiments from our own work.

  4. Electro-membrane processes for flue gas cleaning

    Energy Technology Data Exchange (ETDEWEB)

    Larsen, T. F.

    1997-12-31

    Various techniques for NO removal in Membrane Contactor were considered. However the NO absorption in a liquid adsorbent with chemical enhancement and its ease for regeneration, was selected as the most practicable choice. Various different compounds for chemical enhancement were studied and Fe(II)-chelate enhanced adsorbent was selected for further studies. The technical feasibility of Fe(II)-chelate enhanced adsorbent for obtaining greater than 80% NO removal have been successfully established. Even though the membrane area required for greater than 80% NO removal has been found to be about 500 m{sup 2}/MW{sub c} (compared to 50 - 150 m{sup 2}/MW{sub c}, for 95% SO{sub 2} removal, depending on the membrane characteristics), suitable Membrane Contactor design has been proposed for carrying out the process at an acceptable gas side pressure drop. The electro-membrane processes for the regeneration of adsorbents have been studied both theoretically and experimentally. The theoretical studies have concerned the study of basic functions of both the bipolar membranes and charge laden (anion/cation) membranes. Suitable experimental techniques have been devised for studying of these basic parameters (e.g. charge transport number, salt diffusion through membranes, current-voltage characteristics of bipolar membranes and electrical resistance of charge laden membranes). These parameters have further been utilized in the mechanistic model of combined membranes in an ED cell (electrodialysis). Based on these fundamental studies and analysis of process requirements, suitable configuration of ED cell has been developed and verified by experimental studies. The effect of both the stack design parameters (e.g. number of cells, membrane type and spacer design) and the operational parameters (e.g. temperature, electrolyte concentration, liquid velocity and current density) have been studied for optimization of energy consumption for regeneration of loaded adsorbents. As a result

  5. Physicochemical treatments of anionic surfactants wastewater: Effect on aerobic biodegradability.

    Science.gov (United States)

    Aloui, Fathi; Kchaou, Sonia; Sayadi, Sami

    2009-05-15

    The effect of different physicochemical treatments on the aerobic biodegradability of an industrial wastewater resulting from a cosmetic industry has been investigated. This industrial wastewater contains 11423 and 3148mgL(-1) of chemical oxygen demand (COD) and anionic surfactants, respectively. The concentration of COD and anionic surfactants were followed throughout the diverse physicochemical treatments and biodegradation experiments. Different pretreatments of this industrial wastewater using chemical flocculation process with lime and aluminium sulphate (alum), and also advanced oxidation process (electro-coagulation (Fe and Al) and electro-Fenton) led to important COD and anionic surfactants removals. The best results were obtained using electro-Fenton process, exceeding 98 and 80% of anionic surfactants and COD removals, respectively. The biological treatment by an isolated strain Citrobacter braakii of the surfactant wastewater, as well as the pretreated wastewater by the various physicochemical processes used in this study showed that the best results were obtained with electro-Fenton pretreated wastewater. The characterization of the treated surfactant wastewater by the integrated process (electro-coagulation or electro-Fenton)-biological showed that it respects Tunisian discharge standards.

  6. The anionic biosurfactant rhamnolipid does not denature industrial enzymes

    Directory of Open Access Journals (Sweden)

    Jens Kvist Madsen

    2015-04-01

    Full Text Available Biosurfactants (BS are surface-active molecules produced by microorganisms. Their combination of useful properties and sustainable production make them promising industrial alternatives to petrochemical and oleochemical surfactants. Here we compare the impact of the anionic BS rhamnolipid (RL and the conventional/synthetic anionic surfactant sodium dodecyl sulfate (SDS on the structure and stability of three different commercially used enzymes, namely the cellulase Carezyme® (CZ, the phospholipase Lecitase Ultra® (LT and the α-amylase Stainzyme® (SZ. Our data reveal a fundamental difference in their mode of interaction. SDS shows great diversity of interaction towards the different enzymes. It efficiently unfolds both LT and CZ, but LT is unfolded by SDS through formation of SDS clusters on the protein well below the cmc, while CZ is only unfolded by bulk micelles and on average binds significantly less SDS than LT. SDS binds with even lower stoichiometry to SZ and leads to an increase in thermal stability. In contrast, RL does not affect the tertiary or secondary structure of any enzyme at room temperature, has little impact on thermal stability and only binds detectably (but at low stoichiometries to SZ. Furthermore all enzymes maintain activity at both monomeric and micellar concentrations of RL. We conclude that RL, despite its anionic charge, is a surfactant that does not compromise the structural integrity of industrially relevant proteins. This makes RL a promising alternative to current synthetic anionic surfactants in a wide range of commercial applications.

  7. Membrane dynamics

    DEFF Research Database (Denmark)

    Bendix, Pól Martin

    2015-01-01

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

  8. The use of ion-selective membranes for the recovery of sulphuric acid out of contaminated solutions. Comparing electrodialysis, electro electrodialysis and diffusion dialysis

    International Nuclear Information System (INIS)

    Cattoir, S.

    1998-02-01

    The amount of waste arising from dismantled reactors is minimized by decontamination processes. These processes result in contaminated effluents, containing acid and metal salts. The quantity of final waste can be substantially reduced when the acid is extracted out of the decontamination effluents prior to neutralisation. This report discusses three membrane techniques for the displacement of acids out of mixed acid/salt solutions: electrodialysis (ED), electro electrodialysis (EED) and diffusion dialysis (DD). EED uses an electrical potential difference across an anion-selective membrane; DD uses a concentration difference across an anion-selective membrane; ED uses an electrical potential difference, across an anion- and a cation-selective membrane. EED can displace up to 90% of the sulphuric acid, the amount of metal ions in the displaced-acid solution is less than 1% of the ions in the original contaminated solution. Treatment costs are estimated to about 18 Belgian Francs per litre. In DD the purity of the displaced acid is comparable to EED. Treatment costs are about 21 Belgian Francs per litre. In ED 90% acid-displacement is easily reached, but 5% metal ions are also displaced. Treatment costs are about 6 Belgian Francs per litre. Therefore, in spite of the lower purity of the resulting acid, ED is economically speaking the best choice

  9. Multiple-membrane multiple-electrolyte redox flow battery design

    Science.gov (United States)

    Yan, Yushan; Gu, Shuang; Gong, Ke

    2017-05-02

    A redox flow battery is provided. The redox flow battery involves multiple-membrane (at least one cation exchange membrane and at least one anion exchange membrane), multiple-electrolyte (one electrolyte in contact with the negative electrode, one electrolyte in contact with the positive electrode, and at least one electrolyte disposed between the two membranes) as the basic characteristic, such as a double-membrane, triple electrolyte (DMTE) configuration or a triple-membrane, quadruple electrolyte (TMQE) configuration. The cation exchange membrane is used to separate the negative or positive electrolyte and the middle electrolyte, and the anion exchange membrane is used to separate the middle electrolyte and the positive or negative electrolyte.

  10. Characterization of a supported ionic liquid membrane used for the removal of cyanide from wastewater.

    Science.gov (United States)

    Xue, Juan Qin; Liu, Ni Na; Li, Guo Ping; Dang, Long Tao

    2017-12-01

    This work evaluated the performance of ionic liquids (ILs) in supported liquid membranes in the removal of total cyanide from wastewater. Membranes were characterized by scanning electron microscopy and contact angle measurements to study the membrane morphology and wetting ability. In particular, the effects of operational parameters such as membrane immersion time, feed-phase concentration, and pH on cyanide removal were investigated. ILs are organic salts that are entirely composed of organic cations and either organic or inorganic anions. Since their vapor pressure is negligible, they can be handled easily; this characteristic gives rise to their 'green' nature. In this study, a hydrophobic IL, 1-butyl-3-methylimidazolium hexafluorophosphate ([Bmim]PF 6 ), was immobilized in the pores of a solid polymeric support made of polyvinylidene fluoride. The optimal conditions were as follows: 1 hour membrane immersion time, 312.24 mg/L feed-phase concentration, a feed-phase pH of 4, 3% NaOH solution, and 1 hour stirring time. The cyanide removal was 95.31%. The treatment of cyanide using supported ionic liquid membrane (SILM) technology is a method with potential applications in industry.

  11. Gas separation with membranes

    International Nuclear Information System (INIS)

    Schulz, G.; Michele, H.; Werner, U.

    1982-01-01

    Gas separation with membranes has already been tested in numerous fields of application, e.g. uranium enrichment of H 2 separation. In many of these processes the mass transfer units, so-called permeators, have to be connected in tandem in order to achieve high concentrations. A most economical operating method provides for each case an optimization of the cascades with regard to the membrane materials, construction and design of module. By utilization of the concentration gradient along the membrane a new process development has been accomplished - the continuously operating membrane rectification unit. Investment and operating costs can be reduced considerably for a number of separating processes by combining a membrane rectification unit with a conventional recycling cascade. However, the new procedure requires that the specifications for the module construction, flow design, and membrane properties be reconsidered. (orig.) [de

  12. Separation of some ionic species from solutions by membrane and centrifugation methods

    International Nuclear Information System (INIS)

    Toropov, I.G.; Toropova, V.V.; Davydov, Yu.P.; Zemskova, L.M.

    2003-01-01

    Present work is dedicated to investigation of influence on iron ion hydrolytic behavior of some anions. On the basis of this research one can propose new, quite effective ways for liquid water solution purification. This paper has shown how the knowledge of iron ions behavior in solution can be applied to solve practical tasks. The conditions of formation of Fe(III) polynuclear forms, which are detained by semipermeable membranes have been considered in this research. The influence of a range of anions, some oxidants and reducing agents, affecting the formation of polynuclear hydroxo-forms of iron in solutions, has been studied during this research. It has been demonstrated that multinuclear forms of Fe(III) can interact with an ion of the medium. In this instance anion behaves as a multinuclear particle. In this work the behaviour of iodine during dialysis of solution was investigated. Additionally, it appeared that in the presence of iron polynuclear forms phosphate ion was detained by cellophane membrane. The data show that phosphate ion interacts strongly with the polynuclear forms of iron in aqueous solution. The formation of rather coarse forms of iron takes place at the phosphate ion presence which can be sedimented by centrifugation, and increasing either phosphate ion concentration or pH of solutions results in increase of percentage of the iron sedimented. According to these data phosphate ion can be separated from water solution by way of centrifugation with polynuclear hydroxo particles of iron. (authors)

  13. Electrochemical membrane reactor: In situ separation and recovery of chromic acid and metal ions

    International Nuclear Information System (INIS)

    Khan, Jeeshan; Tripathi, Bijay P.; Saxena, Arunima; Shahi, Vinod K.

    2007-01-01

    An electrochemical membrane reactor with three compartments (anolyte, catholyte and central compartment) based on in-house-prepared cation- and anion-exchange membrane was developed to achieve in situ separation and recovery of chromic acid and metal ions. The physicochemical and electrochemical properties of the ion-exchange membrane under standard operating conditions reveal its suitability for the proposed reactor. Experiments using synthetic solutions of chromate and dichromate of different concentrations were carried out to study the feasibility of the process. Electrochemical reactions occurring at the cathode and anode under operating conditions are proposed. It was observed that metal ion migrated through the cation-exchange membrane from central compartment to catholyte and OH - formation at the cathode leads to the formation of metal hydroxide. Simultaneously, chromate ion migrated through the anion-exchange membrane from central compartment to the anolyte and formed chromic acid by combining H + produced their by oxidative water splitting. Thus a continuous decay in the concentration of chromate and metal ion was observed in the central compartment, which was recovered separately in the anolyte and catholyte, respectively, from their mixed solution. This process was completely optimized in terms of operating conditions such as initial concentration of chromate and metal ions in the central compartment, the applied cell voltage, chromate and metal ion flux, recovery percentage, energy consumption, and current efficiency. It was concluded that chromic acid and metal ions can be recovered efficiently from their mixed solution leaving behind the uncharged organics and can be reused as their corresponding acid and base apart from the purifying water for further applications

  14. Growth of the obligate anaerobe Desulfovibrio vulgaris Hildenborough under continuous low oxygen concentration sparging: impact of the membrane-bound oxygen reductases.

    Science.gov (United States)

    Ramel, Fanny; Brasseur, Gael; Pieulle, Laetitia; Valette, Odile; Hirschler-Réa, Agnès; Fardeau, Marie Laure; Dolla, Alain

    2015-01-01

    Although obligate anaerobe, the sulfate-reducing bacterium Desulfovibrio vulgaris Hildenborough (DvH) exhibits high aerotolerance that involves several enzymatic systems, including two membrane-bound oxygen reductases, a bd-quinol oxidase and a cc(b/o)o3 cytochrome oxidase. Effect of constant low oxygen concentration on growth and morphology of the wild-type, single (Δbd, Δcox) and double deletion (Δcoxbd) mutant strains of the genes encoding these oxygen reductases was studied. When both wild-type and deletion mutant strains were cultured in lactate/sulfate medium under constant 0.02% O2 sparging, they were able to grow but the final biomasses and the growth yield were lower than that obtained under anaerobic conditions. At the end of the growth, lactate was not completely consumed and when conditions were then switched to anaerobic, growth resumed. Time-lapse microscopy revealed that a large majority of the cells were then able to divide (over 97%) but the time to recover a complete division event was longer for single deletion mutant Δbd than for the three other strains. Determination of the molar growth yields on lactate suggested that a part of the energy gained from lactate oxidation was derived toward cells protection/repairing against oxidative conditions rather than biosynthesis, and that this part was higher in the single deletion mutant Δbd and, to a lesser extent, Δcox strains. Our data show that when DvH encounters oxidative conditions, it is able to stop growing and to rapidly resume growing when conditions are switched to anaerobic, suggesting that it enters active dormancy sate under oxidative conditions. We propose that the pyruvate-ferredoxin oxidoreductase (PFOR) plays a central role in this phenomenon by reversibly switching from an oxidative-sensitive fully active state to an oxidative-insensitive inactive state. The oxygen reductases, and especially the bd-quinol oxidase, would have a crucial function by maintaining reducing conditions

  15. Growth of the obligate anaerobe Desulfovibrio vulgaris Hildenborough under continuous low oxygen concentration sparging: impact of the membrane-bound oxygen reductases.

    Directory of Open Access Journals (Sweden)

    Fanny Ramel

    Full Text Available Although obligate anaerobe, the sulfate-reducing bacterium Desulfovibrio vulgaris Hildenborough (DvH exhibits high aerotolerance that involves several enzymatic systems, including two membrane-bound oxygen reductases, a bd-quinol oxidase and a cc(b/oo3 cytochrome oxidase. Effect of constant low oxygen concentration on growth and morphology of the wild-type, single (Δbd, Δcox and double deletion (Δcoxbd mutant strains of the genes encoding these oxygen reductases was studied. When both wild-type and deletion mutant strains were cultured in lactate/sulfate medium under constant 0.02% O2 sparging, they were able to grow but the final biomasses and the growth yield were lower than that obtained under anaerobic conditions. At the end of the growth, lactate was not completely consumed and when conditions were then switched to anaerobic, growth resumed. Time-lapse microscopy revealed that a large majority of the cells were then able to divide (over 97% but the time to recover a complete division event was longer for single deletion mutant Δbd than for the three other strains. Determination of the molar growth yields on lactate suggested that a part of the energy gained from lactate oxidation was derived toward cells protection/repairing against oxidative conditions rather than biosynthesis, and that this part was higher in the single deletion mutant Δbd and, to a lesser extent, Δcox strains. Our data show that when DvH encounters oxidative conditions, it is able to stop growing and to rapidly resume growing when conditions are switched to anaerobic, suggesting that it enters active dormancy sate under oxidative conditions. We propose that the pyruvate-ferredoxin oxidoreductase (PFOR plays a central role in this phenomenon by reversibly switching from an oxidative-sensitive fully active state to an oxidative-insensitive inactive state. The oxygen reductases, and especially the bd-quinol oxidase, would have a crucial function by maintaining

  16. Induction of Apoptosis by Superoxide Anion and the Protective Effects of Selenium and Vitamin E

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Objective The purpose of this study is to investigate the effect of superoxide anion on the apoptosis of cultured fibroblasts and the protective role of selenium and Vitamin E. Methods Cultured fibroblasts (NIH3T3), with or without selenium or vitamin E in the medium, were treated by superoxide anion produced by xanthine/xanthine oxidase reaction system and changes in cell structure and DNA were observed microscopically and electrophoretically. Results Apoptosis was observed when superoxide anion at a concentration of 5 nmol/L or 10 nmol/L had acted on the fibroblasts for 5-10 h. Selenium and Vitamin E in the medium inhibited the apoptosis significantly when their concentrations reached 1.15 mol/L and 2.3 mol/L respectively. Conclusion Selenium and vitamin E have protective effect against the apoptosis induced by superoxide anion. The effect of selenium is more remarkable than that of vitamin E.

  17. Microporous silica membranes

    DEFF Research Database (Denmark)

    Boffa, Vittorio; Yue, Yuanzheng

    2012-01-01

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

  18. Proton-stimulated Cl-HCO3 antiport by basolateral membrane vesicles of lobster hepatopancreas

    International Nuclear Information System (INIS)

    Ahearn, G.A.; Grover, M.L.; Tsuji, R.T.; Clay, L.P.

    1987-01-01

    Purified epithelial basolateral membrane vesicles were prepared from lobster hepatopancreas by sorbitol gradient centrifugation. Na+-K+-adenosinetriphosphatase, alkaline phosphatase, and cytochrome-c oxidase enzyme activities in the final membrane preparation were enriched 9.6-, 1.4-, and 0.4-fold, respectively, compared with their activities in the original tissue homogenate. Vesicle osmotic reactivity was demonstrated using 60-min equilibrium 36 Cl uptake experiments at a variety of transmembrane osmotic gradients. 36 Cl uptake into vesicles preloaded with HCO 3 was significantly greater than into vesicles lacking HCO 3 . This exchange process was stimulated by a transmembrane proton gradient (internal pH greater than external pH). Proton-gradient-dependent Cl-HCO 3 exchange was potential sensitive and stimulated by an electrically negative vesicle interior. 36 Cl influx (4-s exposures) into HCO 3 -loaded vesicles occurred by the combination of 4-acetamido-4'-isothiocyanatostilbene-2,2'-disulfonic acid sensitive, carrier-mediated transfer and apparent diffusion. 36 Cl influx was a hyperbolic function of both internal [HCO 3 ] and internal [Cl]. The two internal anions displayed a 100-fold difference in apparent affinity constants with HCO 3 being strongly preferred. 36 Cl influx was stimulated more by preloaded monovalent than by divalent anions. Na was an inhibitor of proton-dependent anion antiport, whereas K had no effect. A model for HCl-HCO 3 antiport is suggested that employs combined transmembrane concentration gradients of Cl and HCO 3 to power anion exchange and transfer protons against a concentration gradient

  19. Analysis of trace inorganic anions in weak acid salts by single pump cycling-column-switching ion chromatography.

    Science.gov (United States)

    Huang, Zhongping; Ni, Chengzhu; Zhu, Zhuyi; Pan, Zaifa; Wang, Lili; Zhu, Yan

    2015-05-01

    The application of ion chromatography with the single pump cycling-column-switching technique was described for the analysis of trace inorganic anions in weak acid salts within a single run. Due to the hydrogen ions provided by an anion suppressor electrolyzing water, weak acid anions could be transformed into weak acids, existing as molecules, after passing through the suppressor. Therefore, an anion suppressor and ion-exclusion column were adopted to achieve on-line matrix elimination of weak acid anions with high concentration for the analysis of trace inorganic anions in weak acid salts. A series of standard solutions consisting of target anions of various concentrations from 0.005 to 10 mg/L were analyzed, with correlation coefficients r ≥ 0.9990. The limits of detection were in the range of 0.67 to 1.51 μg/L, based on the signal-to-noise ratio of 3 and a 25 μL injection volume. Relative standard deviations for retention time, peak area, and peak height were all less than 2.01%. A spiking study was performed with satisfactory recoveries between 90.3 and 104.4% for all anions. The chromatographic system was successfully applied to the analysis of trace inorganic anions in five weak acid salts. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  20. Test procedure for anion exchange chromatography

    International Nuclear Information System (INIS)

    Cooper, T.D.

    1994-01-01

    Plutonium from stored nitrate solutions will be sorbed onto anion exchange resins and converted to storable plutonium dioxide. Useful information will be simultaneously gained on the thermal stability and ion exchange capacity of four commercially available anion exchange resins over several years and under severe degradative conditions. This information will prove useful in predicting the safe and efficient lifetimes of these resins

  1. Tripodal Receptors for Cation and Anion Sensors

    Directory of Open Access Journals (Sweden)

    David N. Reinhoudt

    2006-08-01

    Full Text Available This review discusses different types of artificial tripodal receptors for the selectiverecognition and sensing of cations and anions. Examples on the relationship between structure andselectivity towards cations and anions are described. Furthermore, their applications as potentiometricion sensing are emphasised, along with their potential applications in optical sensors or optodes.

  2. Neutral anion receptors: design and application

    NARCIS (Netherlands)

    Antonisse, M.M.G.; Reinhoudt, David

    1998-01-01

    After the development of synthetic cation receptors in the late 1960s, only in the past decade has work started on the development of synthetic neutral anion receptors. Combination and preorganization of different anion binding groups, like amides, urea moieties, or Lewis acidic metal centers lead

  3. Ectopic expression of the erythrocyte band 3 anion exchange protein, using a new avian retrovirus vector

    DEFF Research Database (Denmark)

    Fuerstenberg, S; Beug, H; Introna, M

    1990-01-01

    into protein. Using the Escherichia coli beta-galactosidase gene cloned into the vector as a test construct, expression of enzyme activity could be detected in 90 to 95% of transfected target cells and in 80 to 85% of subsequently infected cells. In addition, a cDNA encoding the avian erythrocyte band 3 anion...... exchange protein has been expressed from the vector in both chicken embryo fibroblasts and QT6 cells and appears to function as an active, plasma membrane-based anion transporter. The ectopic expression of band 3 protein provides a visual marker for vector function in these cells....

  4. The roles of organic anion permeases in aluminium resistance and mineral nutrition.

    Science.gov (United States)

    Delhaize, Emmanuel; Gruber, Benjamin D; Ryan, Peter R

    2007-05-25

    Soluble aluminium (Al(3+)) is the major constraint to plant growth on acid soils. Plants have evolved mechanisms to tolerate Al(3+) and one type of mechanism relies on the efflux of organic anions that protect roots by chelating the Al(3+). Al(3+) resistance genes of several species have now been isolated and found to encode membrane proteins that facilitate organic anion efflux from roots. These proteins belong to the Al(3+)-activated malate transporter (ALMT) and multi-drug and toxin extrusion (MATE) families. We review the roles of these proteins in Al(3+) resistance as well as their roles in other aspects of mineral nutrition.

  5. ELECTRODIALYSIS IN THE CONVERSION STEP OF THE CONCENTRATED SALT SOLUTIONS IN THE PROCESS OF BATTERY SCRAP

    Directory of Open Access Journals (Sweden)

    S. I. Niftaliev

    2014-01-01

    Full Text Available Summary. The concentrated sodium sulfate solution is formed during the processing of waste battery scrap. A promising way to further treatment of the concentrated salt solution could be the conversion of these salts into acid and bases by electrodialysis, that can be reused in the same technical process cycle. For carrying out the process of conversion of salts into the corresponding acid and base several cells schemes with different combinations of cation, anion and bipolar membranes are used. At this article a comparative analysis of these cells is carried out. In the cells there were used the membranes МC-40, МА-41 and МB-2I. Acid and base solutions with higher concentration may be obtained during the process of electrodialysis in the circulation mode, when a predetermined amount of salt in the closed loop is run through a set of membranes to obtain the desired concentration of the product. The disadvantages of this method are the high cost of buffer tanks and the need to work with small volumes of treated solutions. In industrial applications it is advisable to use continuous electrodialysis with bipolar membranes, since this configuration allows to increase the number of repeating sections, which is necessary to reduce the energy costs. The increase of the removal rate of salts can be achieved by increasing the process steps, and to produce a more concentrated products after the conversion step can be applied electrodialysis-concentrator or evaporator.

  6. Creating molecular macrocycles for anion recognition

    Directory of Open Access Journals (Sweden)

    Amar H. Flood

    2016-03-01

    Full Text Available The creation and functionality of new classes of macrocycles that are shape persistent and can bind anions is described. The genesis of triazolophane macrocycles emerges out of activity surrounding 1,2,3-triazoles made using click chemistry; and the same triazoles are responsible for anion capture. Mistakes made and lessons learnt in anion recognition provide deeper understanding that, together with theory, now provides for computer-aided receptor design. The lessons are acted upon in the creation of two new macrocycles. First, cyanostars are larger and like to capture large anions. Second is tricarb, which also favors large anions but shows a propensity to self-assemble in an orderly and stable manner, laying a foundation for future designs of hierarchical nanostructures.

  7. Adaptation of H+-pumping and plasma membrane H+ ATPase activity in proteoid roots of white lupin under phosphate deficiency.

    Science.gov (United States)

    Yan, Feng; Zhu, Yiyong; Müller, Caroline; Zörb, Christian; Schubert, Sven

    2002-05-01

    White lupin (Lupinus albus) is able to adapt to phosphorus deficiency by producing proteoid roots that release a huge amount of organic acids, resulting in mobilization of sparingly soluble soil phosphate in rhizosphere. The mechanisms responsible for the release of organic acids by proteoid root cells, especially the trans-membrane transport processes, have not been elucidated. Because of high cytosolic pH, the release of undissociated organic acids is not probable. In the present study, we focused on H+ export by plasma membrane H+ ATPase in active proteoid roots. In vivo, rhizosphere acidification of active proteoid roots was vanadate sensitive. Plasma membranes were isolated from proteoid roots and lateral roots from P-deficient and -sufficient plants. In vitro, in comparison with two types of lateral roots and proteoid roots of P-sufficient plants, the following increase of the various parameters was induced in active proteoid roots of P-deficient plants: (a) hydrolytic ATPase activity, (b) Vmax and Km, (c) H+ ATPase enzyme concentration of plasma membrane, (d) H+-pumping activity, (e) pH gradient across the membrane of plasmalemma vesicles, and (f) passive H+ permeability of plasma membrane. In addition, lower vanadate sensitivity and more acidic pH optimum were determined for plasma membrane ATPase of active proteoid roots. Our data support the hypothesis that in active proteoid root cells, H+ and organic anions are exported separately, and that modification of plasma membrane H+ ATPase is essential for enhanced rhizosphere acidification by active proteoid roots.

  8. Effect of therapeutic concentration of lithium on live HEK293 cells; increase of Na+/K+-ATPase, change of overall protein composition and alteration of surface layer of plasma membrane.

    Science.gov (United States)

    Vosahlikova, Miroslava; Ujcikova, Hana; Chernyavskiy, Oleksandr; Brejchova, Jana; Roubalova, Lenka; Alda, Martin; Svoboda, Petr

    2017-05-01

    The effect of long-term exposure of live cells to lithium cations (Li) was studied in HEK293 cells cultivated in the presence of 1mM LiCl for 7 or 21days. The alteration of Na + /K + -ATPase level, protein composition and biophysical state of plasma membrane was determined with the aim to characterize the physiological state of Li-treated cells. Na + /K + -ATPase level was determined by [ 3 H]ouabain binding and immunoblot assays. Overall protein composition was determined by 2D electrophoresis followed by proteomic analysis by MALDI-TOF MS/MS and LFQ. Li interaction with plasma membrane was characterized by fluorescent probes DPH, TMA-DPH and Laurdan. Na + /K + -ATPase was increased in plasma membranes isolated from cells exposed to Li. Identification of Li-altered proteins by 2D electrophoresis, MALDI-TOF MS/MS and LFQ suggests a change of energy metabolism in mitochondria and cytosol and alteration of cell homeostasis of calcium. Measurement of Laurdan generalized polarization indicated a significant alteration of surface layer of isolated plasma membranes prepared from both types of Li-treated cells. Prolonged exposure of HEK293 cells to 1mM LiCl results in up-regulation of Na + /K + -ATPase expression, reorganization of overall cellular metabolism and alteration of the surface layer/polar head-group region of isolated plasma membranes. Our findings demonstrate adaptation of live HEK293 cell metabolism to prolonged exposure to therapeutic concentration of Li manifested as up-regulation of Na + /K + -ATPase expression, alteration of protein composition and change of the surface layer of plasma membrane. Copyright © 2017 Elsevier B.V. All rights reserved.

  9. Artificial membranes with selective nanochannels for protein transport

    KAUST Repository

    Sutisna, Burhannudin

    2016-09-05

    A poly(styrene-b-tert-butoxystyrene-b-styrene) copolymer was synthesized by anionic polymerization and hydrolyzed to poly(styrene-b-4-hydroxystyrene-b-styrene). Lamellar morphology was confirmed in the bulk after annealing. Membranes were fabricated by self-assembly of the hydrolyzed copolymer in solution, followed by water induced phase separation. A high density of pores of 4 to 5 nm diameter led to a water permeance of 40 L m−2 h−1 bar−1 and molecular weight cut-off around 8 kg mol−1. The morphology was controlled by tuning the polymer concentration, evaporation time, and the addition of imidazole and pyridine to stabilize the terpolymer micelles in the casting solution via hydrogen bond complexes. Transmission electron microscopy of the membrane cross-sections confirmed the formation of channels with hydroxyl groups beneficial for hydrogen-bond forming sites. The morphology evolution was investigated by time-resolved grazing incidence small angle X-ray scattering experiments. The membrane channels reject polyethylene glycol with a molecular size of 10 kg mol−1, but are permeable to proteins, such as lysozyme (14.3 kg mol−1) and cytochrome c (12.4 kg mol−1), due to the right balance of hydrogen bond interactions along the channels, electrostatic attraction, as well as the right pore sizes. Our results demonstrate that artificial channels can be designed for protein transport via block copolymer self-assembly using classical methods of membrane preparation.

  10. Artificial membranes with selective nanochannels for protein transport

    KAUST Repository

    Sutisna, Burhannudin; Polymeropoulos, Georgios; Mygiakis, E.; Musteata, Valentina-Elena; Peinemann, Klaus-Viktor; Smilgies, D. M.; Hadjichristidis, Nikolaos; Nunes, Suzana Pereira

    2016-01-01

    A poly(styrene-b-tert-butoxystyrene-b-styrene) copolymer was synthesized by anionic polymerization and hydrolyzed to poly(styrene-b-4-hydroxystyrene-b-styrene). Lamellar morphology was confirmed in the bulk after annealing. Membranes were fabricated by self-assembly of the hydrolyzed copolymer in solution, followed by water induced phase separation. A high density of pores of 4 to 5 nm diameter led to a water permeance of 40 L m−2 h−1 bar−1 and molecular weight cut-off around 8 kg mol−1. The morphology was controlled by tuning the polymer concentration, evaporation time, and the addition of imidazole and pyridine to stabilize the terpolymer micelles in the casting solution via hydrogen bond complexes. Transmission electron microscopy of the membrane cross-sections confirmed the formation of channels with hydroxyl groups beneficial for hydrogen-bond forming sites. The morphology evolution was investigated by time-resolved grazing incidence small angle X-ray scattering experiments. The membrane channels reject polyethylene glycol with a molecular size of 10 kg mol−1, but are permeable to proteins, such as lysozyme (14.3 kg mol−1) and cytochrome c (12.4 kg mol−1), due to the right balance of hydrogen bond interactions along the channels, electrostatic attraction, as well as the right pore sizes. Our results demonstrate that artificial channels can be designed for protein transport via block copolymer self-assembly using classical methods of membrane preparation.

  11. Anion Gap Blood Test: MedlinePlus Lab Test Information

    Science.gov (United States)

    ... https://medlineplus.gov/labtests/aniongapbloodtest.html Anion Gap Blood Test To use the sharing features on this page, please enable JavaScript. What is an Anion Gap Blood Test? An anion gap blood test is a way ...

  12. Effect of indifferent anions on reactions of cadmium ferrocyanide precipitation

    Energy Technology Data Exchange (ETDEWEB)

    Gyunner, Eh A; Mel' nichenko, L M; Vel' mozhnyj, I S [Simferopol' skij Gosudarstvennyj Univ. (Ukrainian SSR)

    1982-08-01

    To clarify the effect of indifferent anions on the processes of cadmium ferrocyanide precipitation the interaction in six systems of the type CdXsub(m)-Msub(4)R-Hsub(2)O (X-Cl/sup -/, CH/sub 3/COO/sup -/, SO/sub 4//sup 2 -/; M-K/sup +/, NH/sub 4//sup +/; R-(Fe(CN)/sub 6/)/sup 4 -/) is studied using the methods of physicochemical analysis (the method of residual concentrations, refractometry). Composition and formation regions of low-soluble interaction products are determined. Effect of anion X nature on interaction character is stated in the series Cl/sup -/, CH/sub 3/COO/sup -/, SO/sub 4//sup 2 -/ in mixtures with incomplete Cd/sup 2 +/ precipitation a tendency for the increase of Cd/sup 2 +/:R/sup 4 -/ ratios in precipitates formed is observed.

  13. The efficiency of Amberjet 4200 resin in removing nitrate in the presence of competitive anions from Shiraz drinking water.

    Science.gov (United States)

    Dehghani, M; Haghighi, A Binaee; Zamanian, Z

    2010-06-01

    The aim of this research is to study the feasibility of removing nitrates from water by means of anion exchange. In the purposed work an attempt was made to utilize strong basic anion resin to remove nitrate in the presence of competitive anion. Amberjet Cl- 4200 ion exchange resin was used in a batch scale. The fixation rate of nitrate without the presences of any competitive anion was almost constant (94.60-96.43) when the nitrate concentrations are in the range of 100-150 mg L(-1). The fixation rate of nitrate in the presences of two competitive anions (sulphate and chloride) was reduced to 82% when the concentration of nitrate was 100 mg L(-1).

  14. Anion-π Catalysts with Axial Chirality.

    Science.gov (United States)

    Wang, Chao; Matile, Stefan

    2017-09-04

    The idea of anion-π catalysis is to stabilize anionic transition states by anion-π interactions on aromatic surfaces. For asymmetric anion-π catalysis, π-acidic surfaces have been surrounded with stereogenic centers. This manuscript introduces the first anion-π catalysts that operate with axial chirality. Bifunctional catalysts with tertiary amine bases next to π-acidic naphthalenediimide planes are equipped with a bulky aromatic substituent in the imide position to produce separable atropisomers. The addition of malonic acid half thioesters to enolate acceptors is used for evaluation. In the presence of a chiral axis, the selective acceleration of the disfavored but relevant enolate addition was much better than with point chirality, and enantioselectivity could be observed for the first time for this reaction with small-molecule anion-π catalysts. Enantioselectivity increased with the π acidity of the π surface, whereas the addition of stereogenic centers around the aromatic plane did not cause further improvements. These results identify axial chirality of the active aromatic plane generated by atropisomerism as an attractive strategy for asymmetric anion-π catalysis. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  15. Structuring detergents for extracting and stabilizing functional membrane proteins.

    Directory of Open Access Journals (Sweden)

    Rima Matar-Merheb

    Full Text Available BACKGROUND: Membrane proteins are privileged pharmaceutical targets for which the development of structure-based drug design is challenging. One underlying reason is the fact that detergents do not stabilize membrane domains as efficiently as natural lipids in membranes, often leading to a partial to complete loss of activity/stability during protein extraction and purification and preventing crystallization in an active conformation. METHODOLOGY/PRINCIPAL FINDINGS: Anionic calix[4]arene based detergents (C4Cn, n=1-12 were designed to structure the membrane domains through hydrophobic interactions and a network of salt bridges with the basic residues found at the cytosol-membrane interface of membrane proteins. These compounds behave as surfactants, forming micelles of 5-24 nm, with the critical micellar concentration (CMC being as expected sensitive to pH ranging from 0.05 to 1.5 mM. Both by 1H NMR titration and Surface Tension titration experiments, the interaction of these molecules with the basic amino acids was confirmed. They extract membrane proteins from different origins behaving as mild detergents, leading to partial extraction in some cases. They also retain protein functionality, as shown for BmrA (Bacillus multidrug resistance ATP protein, a membrane multidrug-transporting ATPase, which is particularly sensitive to detergent extraction. These new detergents allow BmrA to bind daunorubicin with a Kd of 12 µM, a value similar to that observed after purification using dodecyl maltoside (DDM. They preserve the ATPase activity of BmrA (which resets the protein to its initial state after drug efflux much more efficiently than SDS (sodium dodecyl sulphate, FC12 (Foscholine 12 or DDM. They also maintain in a functional state the C4Cn-extracted protein upon detergent exchange with FC12. Finally, they promote 3D-crystallization of the membrane protein. CONCLUSION/SIGNIFICANCE: These compounds seem promising to extract in a functional state

  16. An improved method for the separation of 210Bi and 210Po from 210Pb by using solid-phase extraction disk membranes: environmental applications

    International Nuclear Information System (INIS)

    Marley, N.A.; Gaffney, J.S.; Orlandini, K.A.; Cunningham, M.M.; Drayton, P.J.

    1999-01-01

    An improved method is described for the rapid separation of 210 Bi and 210 Po from the parent radionuclide, 210 Pb, in environmental samples. After the metals were leached from a variety of matrices, they were converted to their anionic chloride complexes by addition of 1 M HCl. These complexes can be separated by solid-phase extraction with disk extraction membranes impregnated with anionic chelating particles. This separation technique takes advantage of the differences in sorption behavior of the chloride complexes to strongly basic anion exchange groups. The extraction membranes can then be counted directly for 210 Bi and 210 Po. If sufficient time is allowed for ingrowth of the daughter, the concentration of the parent 210 Pb in the original sample can be determined from the concentration of 210 Bi. In addition, the ratios of 210 Bi/ 210 Pb and 210 Po/ 210 Pb can be obtained by immediate extraction of 210 Bi followed by ingrowth of 210 Bi for a second determination to establish 210 Pb concentration levels. This can be accomplished easily in order to estimate the residence times of atmospheric aerosols or aqueous colloidal materials. This new technique avoids the time consuming extraction, precipitation, and electroplating procedures used previously and eliminates the experimental errors associated with multiple sample manipulations. (orig.)

  17. Permeabilitas Membran Transpor Campuran Unsur Tanah Jarang (La, Nd, Gd, Lu Menggunakan Carrier (TBP : D2EHPA Melalui Supported Liquid Membrane

    Directory of Open Access Journals (Sweden)

    Djabal Nur Basir

    2015-01-01

    Full Text Available Methods that have been developed currently for the separation and purification of rare earth elements, REE’s are solvent extraction by through immobilization of an extracting agent in a porous polymeric membrane. This methods beside could increase the transport selectivity, also the amount of carrier was very few. This technique is known as supported liquid membrane, SLM. Research toward transport and separation of REE’s through SLM have been still relatively limited merely to single feed-binary mixture, and one type of carrier. The transport   membrane permeability was obtained in a mixture of REE’s (La,Nd,Gd,Lu using the carrier TBP : D2EHPA by SLM. In this SLM technique, supporting membrane PTFE (polytetrafluoroethylene was soaked in a mixture of TBP carrier (tributilfosfat as a neutral ligand and D2EHPA (acid-2- etilheksilfosfat as anionic ligand with a particular concentration ratio in the solvent kerosene as membrane phase. HCl as receiver phase and solution mixture of REE’s as feed phase. Determination of the REE’s total concentration was carried out by UV-Vis spectrophotometry with NAS (sodium alizarin sulfonate as the colouring agent at pH 4,75 and the solution absorbance was determinated at 534 nm as maximum wavelength. Transport patterns of REE’s on the variation of the concentration of total mixed carrier composition, pH, and concentration  of the receiver phase were done for 300 minutes. The optimum conditions of transport mixture of REE’s (La, Nd, Gd, Lu were feed phase pH 3,0; carrier TBP: D2EHPA (0,3:0,7 M; and receiver phase HCl 3,0 M. In this condition, the transport membrane permeability in mixture of REE’s was 0,1077 cm.menit-1 with the percent of transport was 95,24%.

  18. Radiation deterioration of ion-exchange Nafion N117CS membranes

    International Nuclear Information System (INIS)

    Iwai, Yasunori; Hiroki, Akihiro; Tamada, Masao; Isobe, Kanetsugu; Yamanishi, Toshihiko

    2010-01-01

    The cation-exchange Nafion N117 membranes swelling in electrolyte solution were irradiated with γ-rays or electron beams at various doses up to 1500 kGy in the temperature range from room temperature to 343 K to obtain detailed information on the effect of ion-exchange on the radiation deterioration in mechanical properties and ion-exchange capacity. Considerable deterioration in mechanical properties was observed when the Nafion membranes swelling in electrolyte solution were irradiated. A reason is the promotion of degradation with oxygen molecules produced by the irradiation of electrolyte solution. The concentration of electrolyte solution influenced strongly the radiation deterioration in mechanical properties. Keeping the concentration of metal ions to be negligible is important when electrolyzed highly radioactive solution in the light of the durability of polyperfluorosulfonic acid (PFSA) membrane. A sort of cation in electrolyte solution negligibly influenced radiation deterioration in mechanical properties. A sort of anion in electrolyte solution had negligible effect on radiation deterioration in mechanical properties and ion-exchange capacity. The discrepancy in the radiation deterioration in mechanical properties of Nafion membranes swelling in NaCl solution was observed between the specimens irradiated with γ-rays and electron beams. This discrepancy can be explained from the low diffusivity of oxygen from bulk into the membrane.

  19. Charge- and Size-Selective Molecular Separation using Ultrathin Cellulose Membranes

    KAUST Repository

    Puspasari, Tiara

    2016-08-30

    To date, it is still a challenge to prepare high-flux and highselectivity microporous membranes thinner than 20 nm without introducing defects. In this work, we report for the first time the application of cellulose membranes for selective separation of small molecules. A freestanding cellulose membrane as thin as 10 nm has been prepared through regeneration of trimethylsilyl cellulose (TMSC). The freestanding membrane can be transferred to any desired substrate and shows a normalized flux as high as 700 L m−2 h−1 bar−1 when supported by a porous alumina disc. According to filtration experiments, the membrane exhibits precise size-sieving performances with an estimated pore size between 1.5–3.5 nm depending on the regeneration period and initial TMSC concentration. A perfect discrimination of anionic molecules over neutral species is demonstrated. Moreover, the membrane demonstrates high reproducibility, high scale-up potential, and excellent stability over two months.

  20. Liver plasma membranes: an effective method to analyze membrane proteome.

    Science.gov (United States)

    Cao, Rui; Liang, Songping

    2012-01-01

    Plasma membrane proteins are critical for the maintenance of biological systems and represent important targets for the treatment of disease. The hydrophobicity and low abundance of plasma membrane proteins make them difficult to analyze. The protocols given here are the efficient isolation/digestion procedures for liver plasma membrane proteomic analysis. Both protocol for the isolation of plasma membranes and protocol for the in-gel digestion of gel-embedded plasma membrane proteins are presented. The later method allows the use of a high detergent concentration to achieve efficient solubilization of hydrophobic plasma membrane proteins while avoiding interference with the subsequent LC-MS/MS analysis.

  1. Indium extraction by an acidic extractant associated or not with synergetic agents: importance of inorganic anions

    International Nuclear Information System (INIS)

    Goetz-Grandmont, G.; Taheri, M.; Brunette, J.P.; Leroy, M.J.F.

    1985-01-01

    Thermodynamic data are presented for indium extraction from low acidity media (pH value between 1 and 4) and at low concentration by a chelating extractant alone or associated to a solvatant or a lipophylic ammonium salt. Modifications in the nature and/or concentration of inorganic anions can transform the extraction process and allow to change metal distribution between phases [fr

  2. A two-year monitoring study on anionic detergent, phosphate and ...

    African Journals Online (AJOL)

    Anionic detergent, phosphate and chlorophyll-a concentrations were evaluated in Istanbul Strait between January 2013 and December 2014. Water samples were taken monthly at one station in the strait. The average concentrations of phosphate were 1.38 mg L-1 for surface water and 1.76 mg L -1 for bottom water in 2013 ...

  3. The action of physical power sources on the membranes are containing of ionic channels

    International Nuclear Information System (INIS)

    Qasimov, X.M.; Qurbanov, O.Q.

    2002-01-01

    action of an ionizing radiation the inactivation conductance of the membranes is observed, and inactivation conductance of the membranes has in reversible nature. The conductance of membranes thus decreases on 5-6 orders. The speed of an inactivation conductance of the membranes depends on a radiation dose. So at radiation doses 60 and 80 kV the speed of an inactivation conductance of the membranes is sharply decreased. The observed inactivation conductance of the membranes on the one hand can be connected to sensitivity shift of membranes to the action of modifying agents. On the other hand it can be by outcome of decay of functioning channels, the pioneer which one can be formation of free radicals in membranes which are forming as a result generated by water radiolysis, ambient of the membrane. Can be and other gears which are accounting for process of an inactivation conductance of the membranes, which one in the given article are not esteemed. In the second part of this article the process of change of conductance of the membranes, modified by anion selectivity molecules nystatin relating to group of polyene macrolide antibiotics is studied. The experiments conducted with UV-irradiation and it was shown that the conductance decreases with modified by nystatin of membranes and in during 45 min the conductance reaches to the unmodified membranes. The process of an inactivation conductance of the membranes is reached if into the membranes there is the ergosterol or 7-dehydrocholesterol. A ratio of a weight concentration of sterols in relation to general lipids made value 1:10. At replacement of ergosterol or 7-dehydrocholesterol on cholesterol of an inactivation conductance of the membranes under the action of UV - irradiation is not observed. On our view the process of an inactivation conductance of the membranes in the presence of nystatin is connected to series transformation of ergosterol and 7-dehydrocholesterol in other products of a chemical photolysis of

  4. Molecular Evolution of Slow and Quick Anion Channels (SLACs and QUACs/ALMTs).

    Science.gov (United States)

    Dreyer, Ingo; Gomez-Porras, Judith Lucia; Riaño-Pachón, Diego Mauricio; Hedrich, Rainer; Geiger, Dietmar

    2012-01-01

    Electrophysiological analyses conducted about 25 years ago detected two types of anion channels in the plasma membrane of guard cells. One type of channel responds slowly to changes in membrane voltage while the other responds quickly. Consequently, they were named SLAC, for SLow Anion Channel, and QUAC, for QUick Anion Channel. Recently, genes SLAC1 and QUAC1/ALMT12, underlying the two different anion current components, could be identified in the model plant Arabidopsis thaliana. Expression of the gene products in Xenopus oocytes confirmed the quick and slow current kinetics. In this study we provide an overview on our current knowledge on slow and quick anion channels in plants and analyze the molecular evolution of ALMT/QUAC-like and SLAC-like channels. We discovered fingerprints that allow screening databases for these channel types and were able to identify 192 (177 non-redundant) SLAC-like and 422 (402 non-redundant) ALMT/QUAC-like proteins in the fully sequenced genomes of 32 plant species. Phylogenetic analyses provided new insights into the molecular evolution of these channel types. We also combined sequence alignment and clustering with predictions of protein features, leading to the identification of known conserved phosphorylation sites in SLAC1-like channels along with potential sites that have not been yet experimentally confirmed. Using a similar strategy to analyze the hydropathicity of ALMT/QUAC-like channels, we propose a modified topology with additional transmembrane regions that integrates structure and function of these membrane proteins. Our results suggest that cross-referencing phylogenetic analyses with position-specific protein properties and functional data could be a very powerful tool for genome research approaches in general.

  5. Molecular evolution of slow and quick anion channels (SLACs and QUACs/ALMTs

    Directory of Open Access Journals (Sweden)

    Ingo eDreyer

    2012-11-01

    Full Text Available Electrophysiological analyses conducted about 25 years ago detected two types of anion channels in the plasma membrane of guard cells. One type of channel responds slowly to changes in membrane voltage while the other responds quickly. Consequently, they were named SLAC, for SLow Anion Channel, and QUAC, for QUick Anion Channel. Recently, genes SLAC1 and QUAC1/ALMT12, underlying the two different anion current components, could be identified in the model plant Arabidopsis thaliana. Expression of the gene products in Xenopus oocytes confirmed the quick and slow current kinetics. In this study we provide an overview on our current knowledge on slow and quick anion channels in plants and analyze the molecular evolution of ALMT/QUAC-like and SLAC-like channels. We discovered fingerprints that allow screening databases for these channel types and were able to identify 192 (177 non-redundant SLAC-like and 422 (402 non-redundant ALMT/QUAC-like proteins in the fully sequenced genomes of 32 plant species. Phylogenetic analyses provided new insights into the molecular evolution of these channel types. We also combined sequence alignment and clustering with predictions of protein features, leading to the identification of known conserved phosphorylation sites in SLAC1-like channels along with potential sites that have not been yet experimentally confirmed. Using a similar strategy to analyze the hydropathicity of ALMT/QUAC-like channels, we propose a modified topology with additional transmembrane regions that integrates structure and function of these membrane proteins. Our results suggest that cross-referencing phylogenetic analyses with position-specific protein properties and functional data could be a very powerful tool for genome research approaches in general.

  6. Altered Expression of a Malate-Permeable Anion Channel, OsALMT4, Disrupts Mineral Nutrition1[OPEN

    Science.gov (United States)

    Delhaize, Emmanuel

    2017-01-01

    Aluminum-activated malate transporters (ALMTs) form a family of anion channels in plants, but little is known about most of its members. This study examined the function of OsALMT4 from rice (Oryza sativa). We show that OsALMT4 is expressed in roots and shoots and that the OsALMT4 protein localizes to the plasma membrane. Transgenic rice lines overexpressing (OX) OsALMT4 released malate from the roots constitutively and had 2-fold higher malate concentrations in the xylem sap than nulls, indicating greater concentrations of malate in the apoplast. OX lines developed brown necrotic spots on the leaves that did not appear on nulls. These symptoms were not associated with altered concentrations of any mineral element in the leaves, although the OX lines had higher concentrations of Mn and B in their grain compared with nulls. While total leaf Mn concentrations were not different between the OX and null lines, Mn concentrations in the apoplast were greater in the OX plants. The OX lines also displayed increased expression of Mn transporters and were more sensitive to Mn toxicity than null plants. We showed that the growth of wild-type rice was unaffected by 100 µm Mn in hydroponics but, when combined with 1 mm malate, this concentration inhibited growth. We conclude that increasing OsALMT4 expression affected malate efflux and compartmentation within the tissues, which increased Mn concentrations in the apoplast of leaves and induced the toxicity symptoms. This study reveals new links between malate transport and mineral nutrition. PMID:29101278

  7. High Vacuum Techniques for Anionic Polymerization

    KAUST Repository

    Ratkanthwar, Kedar; Hadjichristidis, Nikolaos; Mays, Jimmy

    2015-01-01

    Anionic polymerization high vacuum techniques (HVTs) are the most suitable for the preparation of polymer samples with well-defined complex macromolecular architectures. Though HVTs require glassblowing skill for designing and making polymerization

  8. Cation–Anion Interactions within the Nucleic Acid Ion Atmosphere Revealed by Ion Counting

    Science.gov (United States)

    Gebala, Magdalena; Giambasu, George M.; Lipfert, Jan; Bisaria, Namita; Bonilla, Steve; Li, Guangchao; York, Darrin M.; Herschlag, Daniel

    2016-01-01

    The ion atmosphere is a critical structural, dynamic, and energetic component of nucleic acids that profoundly affects their interactions with proteins and ligands. Experimental methods that “count” the number of ions thermodynamically associated with the ion atmosphere allow dissection of energetic properties of the ion atmosphere, and thus provide direct comparison to theoretical results. Previous experiments have focused primarily on the cations that are attracted to nucleic acid polyanions, but have also showed that anions are excluded from the ion atmosphere. Herein, we have systematically explored the properties of anion exclusion, testing the zeroth-order model that anions of different identity are equally excluded due to electrostatic repulsion. Using a series of monovalent salts, we find, surprisingly, that the extent of anion exclusion and cation inclusion significantly depends on salt identity. The differences are prominent at higher concentrations and mirror trends in mean activity coefficients of the electrolyte solutions. Salts with lower activity coefficients exhibit greater accumulation of both cations and anions within the ion atmosphere, strongly suggesting that cation–anion correlation effects are present in the ion atmosphere and need to be accounted for to understand electrostatic interactions of nucleic acids. To test whether the effects of cation–anion correlations extend to nucleic acid kinetics and thermodynamics, we followed the folding of P4–P6, a domain of the Tetrahymena group I ribozyme, via single-molecule fluorescence resonance energy transfer in solutions with different salts. Solutions of identical concentration but lower activity gave slower and less favorable folding. Our results reveal hitherto unknown properties of the ion atmosphere and suggest possible roles of oriented ion pairs or anion-bridged cations in the ion atmosphere for electrolyte solutions of salts with reduced activity. Consideration of these new

  9. Study of the simultaneous complexation of a cation and of an anion using functionalized calixarenes; Etude de la complexation simultanee d'un cation et d'un anion par des calixarenes fonctionnalises

    Energy Technology Data Exchange (ETDEWEB)

    Moli, Ch. [CEA Cadarache, Dept. d' Etudes des Dechets, DED, 13 - Saint Paul lez Durance (France)]|[Universite Louis Pasteur, 67 - Strasbourg (France)

    2002-03-01

    The chemical reprocessing of irradiated nuclear fuels leads to the production of high-level radioactive liquid wastes which contain long-lived toxic radioelements. In the framework of the long-term management of these wastes, important research work is carried out for the separation of these radioelements for their further transmutation or immobilization inside specific matrices. These radioelements are present in acid solutions of fission products in the form of cations (cesium), anions (technetium, selenium) and molecules (iodine). Crown calixarenes have been successfully used for the extraction of cesium thanks to their exceptional selectivities. This work is mainly based on the use of the chelating properties of calixarenes for the extraction of anionic radioelements. Calixarenes functionalized by amino-carbon chains have been selected. The synthesis of amine calix[4]arenes and calix[6]arenes is described and their extractive and ionophoretic properties with respect to radioelements are shown using aqueous selective separation techniques like the liquid-liquid extraction and the supported liquid membrane transport. Technetium and selenium are extracted by amine calixarenes from a 10{sup -2} M aqueous solution of nitric acid. At this acidity, no selenium transport is observed, while technetium transport is efficient: the solution is quasi-totally decontaminated in 6 hours. Molecular iodine is efficiently extracted with a simple organic diluent, the 1,2-nitro-phenyl-hexyl-ether, from a strongly concentrated aqueous solution of nitric acid (HNO{sub 3} = 3 M). The transport of iodine becomes faster and more efficient when its concentration in the solution is higher. (J.S.)

  10. Study of the simultaneous complexation of a cation and of an anion using functionalized calixarenes; Etude de la complexation simultanee d'un cation et d'un anion par des calixarenes fonctionnalises

    Energy Technology Data Exchange (ETDEWEB)

    Moli, Ch [CEA Cadarache, Dept. d' Etudes des Dechets, DED, 13 - Saint Paul lez Durance (France); [Universite Louis Pasteur, 67 - Strasbourg (France)

    2002-03-01

    The chemical reprocessing of irradiated nuclear fuels leads to the production of high-level radioactive liquid wastes which contain long-lived toxic radioelements. In the framework of the long-term management of these wastes, important research work is carried out for the separation of these radioelements for their further transmutation or immobilization inside specific matrices. These radioelements are present in acid solutions of fission products in the form of cations (cesium), anions (technetium, selenium) and molecules (iodine). Crown calixarenes have been successfully used for the extraction of cesium thanks to their exceptional selectivities. This work is mainly based on the use of the chelating properties of calixarenes for the extraction of anionic radioelements. Calixarenes functionalized by amino-carbon chains have been selected. The synthesis of amine calix[4]arenes and calix[6]arenes is described and their extractive and ionophoretic properties with respect to radioelements are shown using aqueous selective separation techniques like the liquid-liquid extraction and the supported liquid membrane transport. Technetium and selenium are extracted by amine calixarenes from a 10{sup -2} M aqueous solution of nitric acid. At this acidity, no selenium transport is observed, while technetium transport is efficient: the solution is quasi-totally decontaminated in 6 hours. Molecular iodine is efficiently extracted with a simple organic diluent, the 1,2-nitro-phenyl-hexyl-ether, from a strongly concentrated aqueous solution of nitric acid (HNO{sub 3} = 3 M). The transport of iodine becomes faster and more efficient when its concentration in the solution is higher. (J.S.)

  11. Demonstrate use of capillary electrophoresis low level transient of anions

    International Nuclear Information System (INIS)

    Moum, Kari-Lye; Solheim, Torill; McElrath, Joel; Frattini, Paul

    2012-09-01

    Capillary Electrophoresis (CE) is a well-known analytical method capable of rapid detection of very low concentration of cations and anionic species such as chloride, sulfate and nitrate. These anions are of crucial importance in reducing the potential of stainless steel components to undergo stress corrosion cracking. Currently, Nuclear Power Plants (NPPs) use Ion Chromatography (IC) as the analytical technique to achieve the required detection levels of ionic species. At the Halden Reactor Project (HRP) IC was replaced by CE in 1996, and since then HRP has gained nearly 20 years of operational experience. During the last 15 years, EPRI has done research on the CE technique and has achieved extensive experience in this area. EPRI has demonstrated detection levels at ppt and sub-ppb levels. This paper presents the ability of the CE technique to follow low level transients of anions in Boiling Water Reactor (BWR) coolant. A transient caused by approx. 10 ppb chloride and sulfate was simulated in an experimental circuit simulating BWR conditions. A series of grab samples were taken and analysed using HRPs CE (Agilent G1600). (authors)

  12. Anion Effects on the Ion Exchange Process and the Deformation Property of Ionic Polymer Metal Composite Actuators

    Directory of Open Access Journals (Sweden)

    Wataru Aoyagi

    2016-06-01

    Full Text Available An ionic polymer-metal composite (IPMC actuator composed of a thin perfluorinated ionomer membrane with electrodes plated on both surfaces undergoes a large bending motion when a low electric field is applied across its thickness. Such actuators are soft, lightweight, and able to operate in solutions and thus show promise with regard to a wide range of applications, including MEMS sensors, artificial muscles, biomimetic systems, and medical devices. However, the variations induced by changing the type of anion on the device deformation properties are not well understood; therefore, the present study investigated the effects of different anions on the ion exchange process and the deformation behavior of IPMC actuators with palladium electrodes. Ion exchange was carried out in solutions incorporating various anions and the actuator tip displacement in deionized water was subsequently measured while applying a step voltage. In the step voltage response measurements, larger anions such as nitrate or sulfate led to a more pronounced tip displacement compared to that obtained with smaller anions such as hydroxide or chloride. In AC impedance measurements, larger anions generated greater ion conductivity and a larger double-layer capacitance at the cathode. Based on these mechanical and electrochemical measurements, it is concluded that the presence of larger anions in the ion exchange solution induces a greater degree of double-layer capacitance at the cathode and results in enhanced tip deformation of the IPMC actuators.

  13. Photoelectron spectroscopy of the 6-azauracil anion.

    Science.gov (United States)

    Chen, Jing; Buonaugurio, Angela; Dolgounitcheva, Olga; Zakrzewski, V G; Bowen, Kit H; Ortiz, J V

    2013-02-14

    We report the photoelectron spectrum of the 6-azauracil anion. The spectrum is dominated by a broad band exhibiting a maximum at an electron binding energy (EBE) of 1.2 eV. This spectral pattern is indicative of a valence anion. Our calculations were carried out using ab initio electron propagator and other many-body methods. Comparison of the anion and corresponding neutral of 6-azauracil with those of uracil shows that substituting a nitrogen atom for C-H at the C6 position of uracil gives rise to significant changes in the electronic structure of 6-azauracil versus that of uracil. The adiabatic electron affinity (AEA) of the canonical 6-azauracil tautomer is substantially larger than that of canonical uracil. Among the five tautomeric, 6-azauracil anions studied computationally, the canonical structure was found to be the most stable. The vertical detachment energies (VDE) of the canonical, valence-bound anion of 6-azauracil and its closest "very-rare" tautomer have been calculated. Electron propagator calculations on the canonical anion yield a VDE value that is in close agreement with the experimentally determined VDE value of 1.2 eV. The AEA value of 6-azauracil, assessed at the CCSD(T) level of theory to be 0.5 eV, corresponds with the EBE value of the onset of the experimental spectrum.

  14. Membrane fusion

    DEFF Research Database (Denmark)

    Bendix, Pól Martin

    2015-01-01

    At Stanford University, Boxer lab, I worked on membrane fusion of small unilamellar lipid vesicles to flat membranes tethered to glass surfaces. This geometry closely resembles biological systems in which liposomes fuse to plasma membranes. The fusion mechanism was studied using DNA zippering...... between complementary strands linked to the two apposing membranes closely mimicking the zippering mechanism of SNARE fusion complexes....

  15. Fouling in Membrane Distillation, Osmotic Distillation and Osmotic Membrane Distillation

    Directory of Open Access Journals (Sweden)

    Mourad Laqbaqbi

    2017-03-01

    Full Text Available Various membrane separation processes are being used for seawater desalination and treatment of wastewaters in order to deal with the worldwide water shortage problem. Different types of membranes of distinct morphologies, structures and physico-chemical characteristics are employed. Among the considered membrane technologies, membrane distillation (MD, osmotic distillation (OD and osmotic membrane distillation (OMD use porous and hydrophobic membranes for production of distilled water and/or concentration of wastewaters for recovery and recycling of valuable compounds. However, the efficiency of these technologies is hampered by fouling phenomena. This refers to the accumulation of organic/inorganic deposits including biological matter on the membrane surface and/or in the membrane pores. Fouling in MD, OD and OMD differs from that observed in electric and pressure-driven membrane processes such electrodialysis (ED, membrane capacitive deionization (MCD, reverse osmosis (RO, nanofiltration (NF, ultrafiltration (UF, microfiltration (MF, etc. Other than pore blockage, fouling in MD, OD and OMD increases the risk of membrane pores wetting and reduces therefore the quantity and quality of the produced water or the concentration efficiency of the process. This review deals with the observed fouling phenomena in MD, OD and OMD. It highlights different detected fouling types (organic fouling, inorganic fouling and biofouling, fouling characterization techniques as well as various methods of fouling reduction including pretreatment, membrane modification, membrane cleaning and antiscalants application.

  16. Double-membrane triple-electrolyte redox flow battery design

    Science.gov (United States)

    Yushan, Yan; Gu, Shuang; Gong, Ke

    2018-03-13

    A redox flow battery is provided having a double-membrane (one cation exchange membrane and one anion exchange membrane), triple-electrolyte (one electrolyte in contact with the negative electrode, one electrolyte in contact with the positive electrode, and one electrolyte positioned between and in contact with the two membranes). The cation exchange membrane is used to separate the negative or positive electrolyte and the middle electrolyte, and the anion exchange membrane is used to separate the middle electrolyte and the positive or negative electrolyte. This design physically isolates, but ionically connects, the negative electrolyte and positive electrolyte. The physical isolation offers great freedom in choosing redox pairs in the negative electrolyte and positive electrolyte, making high voltage of redox flow batteries possible. The ionic conduction drastically reduces the overall ionic crossover between negative electrolyte and positive one, leading to high columbic efficiency.

  17. Interaction of a potyviral VPg with anionic phospholipid vesicles

    International Nuclear Information System (INIS)

    Rantalainen, Kimmo I.; Christensen, Peter A.; Hafren, Anders; Otzen, Daniel E.; Kalkkinen, Nisse; Maekinen, Kristiina

    2009-01-01

    The viral genome-linked protein (VPg) of Potato virus A (PVA) is a multifunctional protein that belongs to a class of intrinsically disordered proteins. Typically, this type of protein gains a more stable structure upon interactions or posttranslational modifications. In a membrane lipid strip overlay binding assay, PVA VPg was found to bind phosphatidylserine (PS), but not phosphatidylcholine (PC). According to circular dichroism spectroscopy, the secondary structure of PVA VPg was stabilized upon interactions with PS and phosphatidylglycerol (PG), but not with PC vesicles. It is possible that this stabilizati