WorldWideScience

Sample records for membrane chemical stability

  1. Long term physical and chemical stability of polyelectrolyte multilayer membranes

    NARCIS (Netherlands)

    de Grooth, Joris; Haakmeester, Brian; Wever, Carlos; Potreck, Jens; de Vos, Wiebe Matthijs; Nijmeijer, Dorothea C.

    2015-01-01

    This work presents a detailed investigation into the long term stability of polyelectrolyte multilayer (PEM) modified membranes, a key factor for the application of these membranes in water purification processes. Although PEM modified membranes have been frequently investigated, their long term

  2. Supported liquid membrane stability in chiral resolution by chemically and physically modified membranes

    Energy Technology Data Exchange (ETDEWEB)

    Molinari, R.; Argurio, P. [Arcavata di Rende Univ. of Calabria, Arcavata di Rende, CS (Italy). Dept. of Chemical and Materials Engineering

    2001-04-01

    In the present work some stability studies on Supported Liquid Membranes (SLMs) to be used for chiral separations were realized. In particular, primary aim was to determine how a modification of the support surface influences the SLM stability. First, the procedure for support modification was optimised, making a screening of various compounds (sulphuric acid, nitric acid, chromic acid, sodium dodecyl sulphate (SDS), glycerol, oleic alcohol, propylene glycol (PPG), bovine serum albumin (BSA)) and testing their performance by means of contact angle measurements. Next, a second screening was realized by permeation tests in a stirred cell. Finally, to compare the stability of modified with unmodified support in a process of interest for chemical and/or biochemical industries, some permeation tests for resolution of DNB-DL-Leucine were realized in a re-circulation system. Results showed a better surface hydrophilization of chemically modified support and better stability of the sulphonated support. However, in operating conditions a little high stability of the unmodified support was obtained. [Italian] Nel presente lavoro sono stati realizzati degli studi di stabilita' di Membrane Liquide Supportate (SLMs) da impiegare in separazioni chirali. In particolare, obiettivo principale e' stato quello di determinare l'influenza che una modifica della superficie del supporto ha sulla stabilita' della SLM. Cosi', in un primo momento, e' stata ottimizzata le procedura di modifica del supporto, facendo una selezione tra vari composti (acido solforico, acido nitrico, acido cromico, sodio dodecil solfato (SDS), glicerolo, alcool oleico, glicole propilenico (PPG), siero di albumina bovina (BSA)) basata su misure dell'angolo di contatto. Successivamente, e' stata realizzata una seconda selezione mediante prove di permeazione in una cella agitata. Infine, con lo scopo di confrontare la stabilita' della SLM con supporto modificato rispetto

  3. Oxygen permeation and thermo-chemical stability of oxygen separation membrane materials for the oxyfuel process

    Energy Technology Data Exchange (ETDEWEB)

    Ellett, Anna Judith

    2009-07-01

    analysis (TGA) and thermo mechanical analysis (TMA). An increase in thermal expansion and oxygen permeation associated with an increase in oxygen vacancy concentration, observed also in the TGA curves, occurs during heating. BSCF50 exhibits permeation fluxes well above those of LSCF58, PSCF58 and La{sub 2}NiO{sub 4+{delta}}, which are quite similar to each other. After exposure, no degradation of LSCF58, La{sub 2}NiO{sub 4+{delta}} and PSCF58 occurs. On the other hand BSCF50 is found to be unstable in CO{sub 2}- and/or H{sub 2}O-containing atmospheres and also to exhibit a chemical demixing. The thermo-chemical stability and the oxygen permeation performances are both crucial factors in the selection of high purity oxygen separation membranes for the oxyfuel process, thus making LSCF58, PSCF58 and La{sub 2}NiO{sub 4+{delta}} in this study the most suitable materials for this application. Serious issues arise, however, from the fact that secondary non-ion conducting oxide phases are formed in the bulk of every material, forming obstacles for oxygen ion migration, and also that a reaction with chromia occurs, preventing their use without protection. (orig.)

  4. Nanoporous silica membranes with high hydrothermal stability

    DEFF Research Database (Denmark)

    Boffa, Vittorio; Magnacca, Giualiana; Yue, Yuanzheng

    to improve the stability of nanoporous silica structure. This work is a quantitative study on the impact of type and concentration of transition metal ions on the microporous structure and stability of amorphous silica-based membranes, which provides information on how to design chemical compositions...

  5. Chemical degradation mechanisms of membranes for alkaline membrane fuel cells

    Energy Technology Data Exchange (ETDEWEB)

    Choe, Yoong-Kee [National Institute of Advanced Industrial Science and Technology, Umezono 1-1-1, Tsukuba (Japan); Henson, Neil J.; Kim, Yu Seung [Los Alamos National Laboratory, Los Alamos, NM (United States)

    2015-12-31

    Chemical degradation mechanisms of membranes for alkaline membrane fuel cells have been investigated using density functional theory (DFT). We have elucidated that the aryl-ether moiety of membranes is one of the weakest site against attack of hydroxide ions. The results of DFT calculations for hydroxide initiated aryl-ether cleavage indicated that the aryl-ether cleavage occurred prior to degradation of cationic functional group. Such a weak nature of the aryl-ether group arises from the electron deficiency of the aryl group as well as the low bond dissociation energy. The DFT results suggests that removal of the aryl-ether group in the membrane should enhance the stability of membranes under alkaline conditions. In fact, an ether fee poly(phenylene) membrane exhibits excellent stability against the attack from hydroxide ions.

  6. Role of post-sulfonation of poly(ether ether sulfone) in proton conductivity and chemical stability of its proton exchange membranes for fuel cell

    Energy Technology Data Exchange (ETDEWEB)

    Unveren, Elif Erdal; Erdogan, Tuba; Inan, Tulay Y. [Chemistry Institute, TUBITAK Marmara Research Center, 41470, Gebze, Kocaeli (Turkey); Celebi, Serdar S. [Professor Emeritus, Chemical Engineering Department, Hacettepe University, 06800, Beytepe, Ankara (Turkey)

    2010-04-15

    Commercially available poly(ether ether sulfone), PEES, was directly sulfonated using concentrated sulfuric acid at low temperatures by minimizing degradation during sulfonation. The sulfonation reaction was performed in the temperature range of 5-25 C. Sulfonated polymers were characterized by FTIR, {sup 1}H NMR spectroscopy and ion exchange capacity (IEC) measurements. Degradation during sulfonation was investigated by measuring intrinsic viscosity, glass transition temperature and thermal decomposition temperature of sulfonated polymers. Sulfonated PEES, SPEES, membranes were prepared by solvent casting method and characterized in terms of IEC, proton conductivity and water uptake. The effect of sulfonation conditions on chemical stability of membranes was also investigated via Fenton test. Optimum sulfonation condition was determined to be 10 C with conc. H{sub 2}SO{sub 4} based on the characteristics of sulfonated polymers and also the chemical stability of their membranes. SPEES membranes exhibited proton conductivity up to 185.8 mS cm{sup -1} which is higher than that of Nafion 117 (133.3 mS cm{sup -1}) measured at 80 C and relative humidity 100%. (author)

  7. Membrane Stability Testing

    Energy Technology Data Exchange (ETDEWEB)

    Hobbs, D.T. [Westinghouse Savannah River Company, AIKEN, SC (United States)

    1997-09-30

    The Electrosynthesis Co. Inc. (ESC) was contracted by the Westinghouse Savannah River Company to investigate the long term performance and durability of cell components (anode, membrane, cathode) in an electrochemical caustic recovery process using a simulated SRC liquid waste as anolyte solution. This report details the results of two long-term studies conducted using an ICI FM01 flow cell. This cell is designed and has previously been demonstrated to scale up directly into the commercial scale ICI FM21 cell.

  8. Chemical and radiation stability of a proprietary cesium ion exchange material manufactured from WWL membrane and SuperLig reg-sign 644

    International Nuclear Information System (INIS)

    Brown, G.N.; Carson, K.J.; DesChane, J.R.; Elovich, R.J.; Berry, P.K.

    1996-09-01

    Pretreatment of nuclear process wastes for ion exchange removal of Cs and other radionuclides is one way to minimize amount of high-level radioactive waste at Hanford. This study evaluated Cs-selective SuperLig reg-sign 644 (IBC Advanced Technologies, American Fork UT) entrapped in a proprietary WWL web membrane (3M) for chemical/radiation stability in simulated caustic neutralized current acid waste (NCAW), 0.5M HNO 3 , water, and air. After exposure up to 2.0E+09 rad, the material was evaluated for Cs uptake in 5M sodium NCAW simulants with varying Cs contents. Radiolytic stability appears to be sufficient for ion exchange pretreatment of radioactive Cs: essentially no decrease in Cs selectivity or loading (Kd) was observed during 60 Cs gamma irradiation in water or 0.5M HNO 3 up to 1.0E+09 rad. Cs Kd decreased by a factor of 2 after 2.0E+09 rad exposure. Cs Kd did not change during irradiation in 5M NCAW or ambient air up to 1.0E+08 rad, but decreased by more than an order of magnitude between 1.0E+08 and 2.0E+09 rad (not typical of process conditions). Chemical stability under caustic conditions is lower than in air or under neutral/acidic conditions. Results indicate that this material is less stable in caustic solution irrespective of radiation exposure. Samples of the membrane retained their physical form throughout the entire experiment and were only slightly brittle after exposure to 2.0E+09 rad. (The material evaluated was a finely ground (400 mesh) particulate engineered to form a polymeric fiber (WWL), not the macroscopic form of SuperLig reg-sign 644 resin (20 to 50 mesh).)

  9. Evaluation of antioxidant capacity and membrane stabilizing ...

    African Journals Online (AJOL)

    Both the leaf and root of C. adenocaulis were extracted with 70% ethanol to yield the ... ELE and ERE were able to protect red blood cell (RBC) membrane against ... antioxidant, anti-inflammatory, lipid peroxidation, membrane stabilization.

  10. Chemically stabilized soils.

    Science.gov (United States)

    2009-12-01

    The objective of this study was to conduct laboratory evaluations to quantify the effects of compaction and moisture conditions on the strength of chemically treated soils typical utilized in pavement construction in Mississippi.

  11. Isomeric Detergent Comparison for Membrane Protein Stability

    DEFF Research Database (Denmark)

    Cho, Kyung Ho; Hariharan, Parameswaran; Mortensen, Jonas S.

    2016-01-01

    and utility, particularly for eukaryotic membrane proteins and membrane protein complexes. Thus, a number of new agents have been devised; some have made significant contributions to membrane protein structural studies. However, few detergent design principles are available. In this study, we prepared meta...... and ortho isomers of the previously reported para-substituted xylene-linked maltoside amphiphiles (XMAs), along with alkyl chain-length variation. The isomeric XMAs were assessed with three membrane proteins, and the meta isomer with a C12 alkyl chain was most effective at maintaining solubility....../stability of the membrane proteins. We propose that interplay between the hydrophile–lipophile balance (HLB) and alkyl chain length is of central importance for high detergent efficacy. In addition, differences in inter-alkyl-chain distance between the isomers influence the ability of the detergents to stabilise membrane...

  12. Comparative antioxidant capacity, membrane stabilization ...

    African Journals Online (AJOL)

    STORAGESEVER

    2008-09-03

    Sep 3, 2008 ... chased from Sigma Chemical Company (Sigma Germany). Vitamin. C used was a product of Glaxo ... mortar and pestle. Weighed portion of each plant part powder was then extracted. Preparation of plant extracts. Cold extraction method was used for the extraction. 20 g of the powdered sample were ...

  13. Studies on the chemical constituents, antioxidants and membrane ...

    African Journals Online (AJOL)

    The chemical constituents, antioxidant and membrane stability activities of Hibiscus rosa sinensis Linn. (Malvaceae) flower were determined. The total anthocyanin was 165 mg / kg with about 6 % reduction due to fermentation. Tannin, ascorbic acid, and total polyphenol were 11.8 g / kg; 478 mg / kg; and 14.4 mg / g, ...

  14. Chemical and thermal stability of insulin

    DEFF Research Database (Denmark)

    Huus, Kasper; Havelund, Svend; Olsen, Helle B

    2006-01-01

    To study the correlation between the thermal and chemical stability of insulin formulations with various insulin hexamer ligands.......To study the correlation between the thermal and chemical stability of insulin formulations with various insulin hexamer ligands....

  15. Stability of model membranes in extreme environments.

    Science.gov (United States)

    Namani, Trishool; Deamer, David W

    2008-08-01

    The first forms of cellular life required a source of amphiphilic compounds capable of assembling into stable boundary structures. Membranes composed of fatty acids have been proposed as model systems of primitive membranes, but their bilayer structure is stable only within a narrow pH range and low ionic strength. They are particularly sensitive to aggregating effects of divalent cations (Mg+2, Ca+2, Fe+2) that would be present in Archaean sea water. Here we report that mixtures of alkyl amines and fatty acids form vesicles at strongly basic and acidic pH ranges which are resistant to the effects of divalent cations up to 0.1 M. Vesicles formed by mixtures of decylamine and decanoic acid (1:1 mole ratio) are relatively permeable to pyranine, a fluorescent anionic dye, but permeability could be reduced by adding 2 mol% of a polycyclic aromatic hydrocarbon such as pyrene. Permeability to the dye was also reduced by increasing the chain length of the amphiphiles. For instance, 1:1 mole ratio mixtures of dodecylamine and dodecanoic acid were able to retain pyranine dye during and following gel filtration. We conclude that primitive cell membranes were likely to be composed of mixtures of amphiphilic and hydrophobic molecules that manifested increased stability over pure fatty acid membranes.

  16. Membrane technology: in the chemical industry

    National Research Council Canada - National Science Library

    Nunes, S. P; Peinemann, K. V

    2001-01-01

    ... terephthalate) 15 22 23 32 37 5 5.1 5.2 5.3 5.4 Surface Modification of Membranes Chemical Oxidation 39 Plasma Treatment 40 Classical Organic Reactions 41 Polymer Grafting 41 39VI Contents 6 6.1 ...

  17. Membrane Stabilizing Activity And Phytochemistry Of Hibiscus rosa ...

    African Journals Online (AJOL)

    The human erythrocyte membrane stabilizing activity of saline extract of Hibiscus rosa-sinensis leaves was investigated as part of efforts at validating its use as anti-arthritic and anti-inflammatory agent. The results of the membrane stabilizing activity of the extract, when compared to two non-steroidal anti-inflammatory drugs ...

  18. Hydrothermal stability of microporous silica and niobia-silica membranes

    NARCIS (Netherlands)

    Boffa, V.; Blank, David H.A.; ten Elshof, Johan E.

    2008-01-01

    The hydrothermal stability of microporous niobia–silica membranes was investigated and compared with silica membranes. The membranes were exposed to hydrothermal conditions at 150 and 200 °C for 70 h. The change of pore structure before and after exposure to steam was probed by single-gas permeation

  19. Chemical stabilization of graphite surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Bistrika, Alexander A.; Lerner, Michael M.

    2018-04-03

    Embodiments of a device, or a component of a device, including a stabilized graphite surface, methods of stabilizing graphite surfaces, and uses for the devices or components are disclosed. The device or component includes a surface comprising graphite, and a plurality of haloaryl ions and/or haloalkyl ions bound to at least a portion of the graphite. The ions may be perhaloaryl ions and/or perhaloalkyl ions. In certain embodiments, the ions are perfluorobenzenesulfonate anions. Embodiments of the device or component including stabilized graphite surfaces may maintain a steady-state oxidation or reduction surface current density after being exposed to continuous oxidation conditions for a period of at least 1-100 hours. The device or component is prepared by exposing a graphite-containing surface to an acidic aqueous solution of the ions under oxidizing conditions. The device or component can be exposed in situ to the solution.

  20. Colour-Value Based Method for Polydopamine Coating-Stability Characterization on Polyethersulfone Membranes.

    Science.gov (United States)

    Bucher, Thomas; Clodt, Juliana I; Grabowski, Andrej; Hein, Martin; Filiz, Volkan

    2017-12-16

    Porous polyethersulfone membranes as used in oenology were investigated in order to evaluate temperature-dependent permeances in a temperature range from 10 to 35 °C. A temperature correction factor was determined for this type of membrane to get accurate and comparable results for further developments. Moreover, the membranes were modified with a bio-inspired polydopamine coating in order to reduce fouling. The performance of the membranes could be increased with respect to permeance and flux recovery under cross-flow conditions. In order to test the applicability and stability of the coating layer, they were treated with basic and acidic cleaning agents as used in industry for fouled membranes. The chemical stability of the coating layer was studied under basic and acidic conditions, by systematic observation of the colour change of the coated membranes over treatment time.

  1. Improvement of Expansive Soils Using Chemical Stabilizers

    Science.gov (United States)

    Ikizler, S. B.; Senol, A.; Khosrowshahi, S. K.; Hatipoğlu, M.

    2014-12-01

    The aim of this study is to investigate the effect of two chemical stabilizers on the swelling potential of expansive soil. A high plasticity sodium bentonite was used as the expansive soil. The additive materials including fly ash (FA) and lime (L) were evaluated as potential stabilizers to decrease the swelling pressure of bentonite. Depending on the type of additive materials, they were blended with bentonite in different percentages to assess the optimum state and approch the maximum swell pressure reduction. According to the results of swell pressure test, both fly ash and lime reduce the swelling potential of bentonite but the maximum improvement occurs using bentonite-lime mixture while the swelling pressure reduction approaches to 49%. The results reveal a significant reduction of swelling potential of expansive soil using chemical stabilizers. Keywords: Expansive soil; swell pressure; chemical stabilization; fly ash; lime

  2. Optimizing the dosage of stabilizing chemical

    OpenAIRE

    Harjula, Tomi

    2013-01-01

    A chemical company provides chemical treatment at customer mill in paper industry. This thesis work was done to determine the optimum dosage of stabilizing chemical. The theoretical framework explains the basics of paper brightness and bleaching and how these topics are connected to each other. The knowledge gained is very valuable and can possibly be used in the future in other similar applications as well. This thesis work contains confidential back ground information. Key ...

  3. Stabilized ultrathin liquid membranes for gas separations

    International Nuclear Information System (INIS)

    Deetz, D.W.

    1987-01-01

    Although immobilized liquid membranes have the desirable properties of high selectivity and permeability, their practical application to gas phase separations is hindered because of the instability of the liquid phase and the relative thickness of current membranes. The problem of liquid instability, which is due to both liquid volatilization and flooding, can be reduced, or eliminated, by immobilizing the liquid phase in pores small enough to significantly reduce the molar free energy of the solution via the Kelvin effect. The obstacle of membrane thickness can be overcome by selectively immobilizing the liquid phase into the skin of a porous asymmetric membranes

  4. Tandem Facial Amphiphiles for Membrane Protein Stabilization

    DEFF Research Database (Denmark)

    Chae, Pil Seok; Gotfryd, Kamil; Pacyna, Jennifer

    2010-01-01

    We describe a new type of synthetic amphiphile that is intended to support biochemical characterization of intrinsic membrane proteins. Members of this new family displayed favorable behavior with four of five membrane proteins tested, and these amphiphiles formed relatively small micelles....

  5. New Developments in Membrane-Based Chemical Separations

    National Research Council Canada - National Science Library

    Jirage, Kshama

    1998-01-01

    Membrane based chemical separations is an emerging field of research. This is because membrane-based separations are potentially less energy intensive and more cost effective than competing separation methods...

  6. Radio-chemical applications of functionalized membranes

    International Nuclear Information System (INIS)

    Pandey, Ashok K.

    2011-01-01

    Functionalized polymer membranes have many potential applications as they are task specific. We have developed many functionalized membranes like polymer inclusion membranes, pore-filled membranes and nano-membranes. Radiotracers and other methods have been used to understand the diffusional-transport properties of the Nafion-117 membrane as well as home-made membranes. These membranes have been used to develop novel analytical and separation methods for toxic metal ions and radionuclides. In this talk, an overview of our work on functionalized membrane is presented. (author)

  7. Influence of Erythrocyte Membrane Stability in Atherosclerosis.

    Science.gov (United States)

    da Silva Garrote-Filho, Mario; Bernardino-Neto, Morun; Penha-Silva, Nilson

    2017-04-01

    The purpose of this study is to show how an excess of cholesterol in the erythrocyte membrane contributes stochastically to the progression of atherosclerosis, leading to damage in blood rheology and O 2 transport, deposition of cholesterol (from trapped erythrocytes) in an area of intraplaque hemorrhage, and local exacerbation of oxidative stress. Cholesterol contained in the membrane of erythrocytes trapped in an intraplaque hemorrhage contributes to the growth of the necrotic nucleus. There is even a relationship between the amount of cholesterol in the erythrocyte membrane and the severity of atherosclerosis. In addition, the volume variability among erythrocytes, measured by RDW, is predictive of a worsening of this disease. Erythrocytes contribute to the development of atherosclerosis in several ways, especially when trapped in intraplate hemorrhage. These erythrocytes are oxidized and phagocytosed by macrophages. The cholesterol present in the membrane of these erythrocytes subsequently contributes to the growth of the atheroma plaque. In addition, when they rupture, erythrocytes release hemoglobin, which leads to the generation of free radicals. Finally, increased RDW may predict the worsening of atherosclerosis, due to the effects of inflammation and oxidative stress on erythropoiesis and erythrocyte volume. A better understanding of erythrocyte participation in atherosclerosis may contribute to the improvement of the prevention and treatment strategies of this disease.

  8. RADIATION STABILITY OF NAFION MEMBRANES USED FOR ISOTOPE SEPARATION BY PROTON EXCHANGE MEMBRANE ELECTROLYSIS

    International Nuclear Information System (INIS)

    Fox, E.

    2009-01-01

    Proton Exchange Membrane Electrolyzers have potential interest for use for hydrogen isotope separation from water. In order for PEME to be fully utilized, more information is needed on the stability of Nafion when exposed to radiation. This work examines Nafion 117 under varying exposure conditions, including dose rate, total dosage and atmospheric condition. Analytical tools, such as FT-IR, ion exchange capacity, DMA and TIC-TOC were used to characterize the exposed membranes. Analysis of the water from saturated membranes can provide important data on the stability of the membranes during radiation exposure. It was found that the dose rate of exposure plays an important role in membrane degradation. Potential mechanisms for membrane degradation include peroxide formation by free radicals

  9. RADIATION STABILITY OF NAFION MEMBRANES USED FOR ISOTOPE SEPARATION BY PROTON EXCHANGE MEMBRANE ELECTROLYSIS

    Energy Technology Data Exchange (ETDEWEB)

    Fox, E

    2009-05-15

    Proton Exchange Membrane Electrolyzers have potential interest for use for hydrogen isotope separation from water. In order for PEME to be fully utilized, more information is needed on the stability of Nafion when exposed to radiation. This work examines Nafion 117 under varying exposure conditions, including dose rate, total dosage and atmospheric condition. Analytical tools, such as FT-IR, ion exchange capacity, DMA and TIC-TOC were used to characterize the exposed membranes. Analysis of the water from saturated membranes can provide important data on the stability of the membranes during radiation exposure. It was found that the dose rate of exposure plays an important role in membrane degradation. Potential mechanisms for membrane degradation include peroxide formation by free radicals.

  10. Plasma membrane aquaporins mediates vesicle stability in broccoli.

    Directory of Open Access Journals (Sweden)

    Maria Del Carmen Martínez-Ballesta

    Full Text Available The use of in vitro membrane vesicles is attractive because of possible applications in therapies. Here we aimed to compare the stability and functionality of plasma membrane vesicles extracted from control and salt-treated broccoli. The impact of the amount of aquaporins was related to plasma membrane osmotic water permeability and the stability of protein secondary structure. Here, we describe for first time an increase in plant aquaporins acetylation under high salinity. Higher osmotic water permeability in NaCl vesicles has been related to higher acetylation, upregulation of aquaporins, and a more stable environment to thermal denaturation. Based on our findings, we propose that aquaporins play an important role in vesicle stability.

  11. Ceramic membrane fouling during ultrafiltration of oil/water emulsions: Roles played by stabilization surfactants of oil droplets

    KAUST Repository

    Lu, Dongwei

    2015-04-07

    Oil/water (O/W) emulsion stabilized by surfactants is the part of oily wastewater that is most difficult to handle. Ceramic membrane ultrafiltration presently is an ideal process to treat O/W emulsions. However, little is known about the fouling mechanism of the ceramic membrane during O/W emulsion treatment. This paper investigated how stabilization surfactants of O/W emulsions influence the irreversible fouling of ceramic membranes during ultrafiltration. An unexpected phenomenon observed was that irreversible fouling was much less when the charge of the stabilization surfactant of O/W emulsions is opposite to the membrane. The less ceramic membrane fouling in this case was proposed to be due to a synergetic steric effect and demulsification effect which prevented the penetration of oil droplets into membrane pores and led to less pore blockage. This proposed mechanism was supported by cross section images of fouled and virgin ceramic membranes taken with scanning electron microscopy, regression results of classical fouling models, and analysis of organic components rejected by the membrane. Furthermore, this mechanism was also verified by the existence of a steric effect and demulsification effect. Our finding suggests that ceramic membrane oppositely charged to the stabilization surfactant should be applied in ultrafiltration of O/W emulsions to alleviate irreversible membrane fouling. It could be a useful rule for ceramic membrane ultrafiltration of oily wastewater. © 2015 American Chemical Society.

  12. Mercury stabilization in chemically bonded phosphate ceramics

    International Nuclear Information System (INIS)

    Wagh, A. S.; Singh, D.; Jeong, S. Y.

    2000-01-01

    Mercury stabilization and solidification is a significant challenge for conventional stabilization technologies. This is because of the stringent regulatory limits on leaching of its stabilized products. In a conventional cement stabilization process, Hg is converted at high pH to its hydroxide, which is not a very insoluble compound; hence the preferred route for Hg sulfidation to convert it into insoluble cinnabar (HgS). Unfortunately, efficient formation of this compound is pH-dependent. At a high pH, one obtains a more soluble Hg sulfate, in a very low pH range, insufficient immobilization occurs because of the escape of hydrogen sulfide, while efficient formation of HgS occurs only in a moderately acidic region. Thus, the pH range of 4 to 8 is where stabilization with Chemically Bonded Phosphate Ceramics (CBPC) is carried out. This paper discusses the authors experience on bench-scale stabilization of various US Department of Energy (DOE) waste streams containing Hg in the CBPC process. This process was developed to treat DOE's mixed waste streams. It is a room-temperature-setting process based on an acid-base reaction between magnesium oxide and monopotassium phosphate solution that forms a dense ceramic within hours. For Hg stabilization, addition of a small amount ( 2 S or K 2 S is sufficient in the binder composition. Here the Toxicity Characteristic Leaching Procedure (TCLP) results on CBPC waste forms of surrogate waste streams representing secondary Hg containing wastes such as combustion residues and Delphi DETOXtrademark residues are presented. The results show that although the current limit on leaching of Hg is 0.2 mg/L, the results from the CBPC waste forms are at least one order lower than this stringent limit. Encouraged by these results on surrogate wastes, they treated actual low-level Hg-containing mixed waste from their facility at Idaho. TCLP results on this waste are presented here. The efficient stabilization in all these cases is

  13. Salinity induced changes in cell membrane stability, protein and ...

    African Journals Online (AJOL)

    control), 4.7, 9.4 and 14.1 dS m-1 to determine the effect of salt on vegetative growth, relative water content, cell membrane stability, protein and RNA contents in sand culture experiment. Fresh and dry weights of plants, shoots and roots decreased ...

  14. In vitro antioxidant and membrane stabilization activities of the fruit ...

    African Journals Online (AJOL)

    Arthritis is an inflammation of one or more joints. There is considerable experimental evidence linking lysosomal enzymes with tissue damage in arthritis. This study investigated anti-arthritic properties of Tetrapleura tetraptera (TT) using membrane stabilization assay (MSA). Powdered TT fruit sample was extracted by ...

  15. Surface Modifications of Support Partitions for Stabilizing Biomimetic Membrane Arrays

    DEFF Research Database (Denmark)

    Perry, Mark; Hansen, Jesper Schmidt; Jensen, Karin Bagger Stibius

    2011-01-01

    with a high signal-to-noise (s/n) ratio. We demonstratesd this by reconstituting gA and α-hemolysin (α-HL) into BLM arrays. The improvement in membrane array lifetime and s/n ratio demonstrates that surface plasma polymerization of the supporting partition can be used to increase the stability of biomimetic......Black lipid membrane (BLM) formation across apertures in an ethylene tetra-fluoroethylene (ETFE) partition separating two aqueous compartments is an established technique for the creation of biomimetic membranes. Recently multi-aperture BLM arrays have attracted interest and in order to increase...... BLM array stability we studied the effect of covalently modifying the partition substrate using surface plasma polymerization with hydrophobic n-hexene, 1-decene and hexamethyldisiloxane (HMDSO) as modification groups. Average lifetimes across singlesided HMDSO modified partitions or using 1-decene...

  16. Self-assembling peptides form nanodiscs that stabilize membrane proteins

    DEFF Research Database (Denmark)

    Midtgaard, Søren Roi; Pedersen, Martin Cramer; Kirkensgaard, Jacob Judas Kain

    2014-01-01

    -ray scattering (SAXS) and small-angle neutron scattering (SANS) supported by coarse-grained molecular dynamics simulations. The detailed structure of the discs was determined in unprecedented detail and it was found that they adopt a discoidal structure very similar to the ApoA1 based nanodiscs. We furthermore...... show that, like the ApoA1 and derived nanodiscs, these peptide discs can accommodate and stabilize a membrane protein. Finally, we exploit their dynamic properties and show that the 18A discs may be used for transferring membrane proteins and associated phospholipids directly and gently......New methods to handle membrane bound proteins, e.g. G-protein coupled receptors (GPCRs), are highly desirable. Recently, apoliprotein A1 (ApoA1) based lipoprotein particles have emerged as a new platform for studying membrane proteins, and it has been shown that they can self...

  17. Effect of Time in Chemical Cleaning of Ultrafiltration Membranes

    NARCIS (Netherlands)

    Levitsky, I.; Naim, R.; Duek, A.; Gitis, V.

    2012-01-01

    Chemical cleaning of ultrafiltration membranes is often considered successful when the flux through a cleaned membrane is much higher than through a pristine one. Here, a novel definition of cleaning intensity is proposed as the product of the concentration of the cleaning agent and the cleaning

  18. Analysis of cerium-composite polymer-electrolyte membranes during and after accelerated oxidative-stability test

    Science.gov (United States)

    Shin, Dongwon; Han, Myungseong; Shul, Yong-Gun; Lee, Hyejin; Bae, Byungchan

    2018-02-01

    The oxidative stability of membranes constructed from a composite of pristine sulfonated poly(arylene ether sulfone) and cerium was investigated by conducting an accelerated oxidative-stability test at the open-circuit voltage (OCV). The membranes were analyzed in situ through OCV and impedance measurements, cyclic voltammetry, and linear-sweep voltammetry to monitor the electrochemical properties during the stability test. Although the high-frequency resistance of a composite membrane was slightly higher than that of a pristine membrane because of the exchange of protons from the sulfonic acid with cerium ions, the composite membrane maintained its potential for much longer than the pristine membrane. The effect of the cerium ions as radical scavengers was confirmed by analyzing the drain water and chemical structure after operation. These post-operation analyses confirmed that cerium ions improved the oxidative stability of the hydrocarbon-based polymer during fuel-cell operation. It is clear that the cerium-based radical scavengers prevented chemical degradation of the polymer membrane as well as the electrode in terms of hydrogen cross-over, polymer-chain scission, and the electrochemical surface area, while they rarely diffused outward from the membrane.

  19. 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

  20. 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.

  1. Yttria-stabilized zirconia as membrane material for electrolytic deoxidation of CaO-CaCl{sub 2} melts

    Energy Technology Data Exchange (ETDEWEB)

    Martin, A.; Poignet, J. C.; Fouletier, J. [Univ Grenoble, LEPMI, CNRS, INPG, UJF, F-38402 St Martin Dheres (France); Allibert, M. [LPSC, F-38026 Grenoble 1 (France); Lambertin, D. [SPDE, CEA Marcoule, F-30207 Bagnols Sur Ceze (France); Bourges, G. [SRPU, CEA Valduc, F-21120 Is Sur Tille (France)

    2010-07-01

    This article is devoted to the study of the stability of an yttria-stabilized zirconia membrane used in the electrolysis of molten CaCl{sub 2}-CaO mixtures at 850 degrees C. Intentiostatic and potentiostatic electrolysis were carried for periods ranging from 10 to 20 h. Post-mortem composition profiles across the zirconia membrane were determined using Raman spectroscopy and microprobe analysis. The membrane degradation was analyzed in terms of synergetic parameters, i. e., chemical, electrochemical, and thermomechanical effects. (authors)

  2. Can Stabilization and Inhibition of Aquaporins Contribute to Future Development of Biomimetic Membranes?

    Science.gov (United States)

    To, Janet; Torres, Jaume

    2015-08-10

    In recent years, the use of biomimetic membranes that incorporate membrane proteins, i.e., biomimetic-hybrid membranes, has increased almost exponentially. Key membrane proteins in these systems have been aquaporins, which selectively permeabilize cellular membranes to water. Aquaporins may be incorporated into synthetic lipid bilayers or to more stable structures made of block copolymers or solid-state nanopores. However, translocation of aquaporins to these alien environments has adverse consequences in terms of performance and stability. Aquaporins incorporated in biomimetic membranes for use in water purification and desalination should also withstand the harsh environment that may prevail in these conditions, such as high pressure, and presence of salt or other chemicals. In this respect, modified aquaporins that can be adapted to these new environments should be developed. Another challenge is that biomimetic membranes that incorporate high densities of aquaporin should be defect-free, and this can only be efficiently ascertained with the availability of completely inactive mutants that behave otherwise like the wild type aquaporin, or with effective non-toxic water channel inhibitors that are so far inexistent. In this review, we describe approaches that can potentially be used to overcome these challenges.

  3. Can Stabilization and Inhibition of Aquaporins Contribute to Future Development of Biomimetic Membranes?

    Directory of Open Access Journals (Sweden)

    Janet To

    2015-08-01

    Full Text Available In recent years, the use of biomimetic membranes that incorporate membrane proteins, i.e., biomimetic-hybrid membranes, has increased almost exponentially. Key membrane proteins in these systems have been aquaporins, which selectively permeabilize cellular membranes to water. Aquaporins may be incorporated into synthetic lipid bilayers or to more stable structures made of block copolymers or solid-state nanopores. However, translocation of aquaporins to these alien environments has adverse consequences in terms of performance and stability. Aquaporins incorporated in biomimetic membranes for use in water purification and desalination should also withstand the harsh environment that may prevail in these conditions, such as high pressure, and presence of salt or other chemicals. In this respect, modified aquaporins that can be adapted to these new environments should be developed. Another challenge is that biomimetic membranes that incorporate high densities of aquaporin should be defect-free, and this can only be efficiently ascertained with the availability of completely inactive mutants that behave otherwise like the wild type aquaporin, or with effective non-toxic water channel inhibitors that are so far inexistent. In this review, we describe approaches that can potentially be used to overcome these challenges.

  4. CHEMICAL CLEANING OF NANOFILTRATION MEMBRANES FOULED BY ORGANIC MATTERS

    Directory of Open Access Journals (Sweden)

    CHARLENE C. H. KOO

    2016-07-01

    Full Text Available Membrane fouling is a term to describe non-integral substance on membrane surface which results in rapid decline of permeation flux and deteriorate the performance of membrane. Chemical cleaning agents especially like alkaline cleaners are most widely employed to restore the membrane performance. This research mainly investigated the potential use of sodium hydroxide (NaOH and sodium hypochlorite (NaOCl as the chemical cleaning agents to restore the permeate flux of organically fouled nanofiltration (NF membranes under varying applied pressure and flow condition. The performances of the cleaning protocols were quantified using flux recovery and resistance removal. The results demonstrated that NaOCl is more effective than NaOH. This observation is also in line with FTIR analysis in which the transmittance intensity showed by FTIR spectra of NaOCl is higher than that of NaOH. The results also reported that higher flux recovery and resistance removal were achieved when the fouled NF membranes were cleaned with higher concentration of chemical agents and applied pressure. However, the improvements of flux recovery and resistance removal by increasing the applied pressure were found insignificant at higher applied pressure range (16 to 18 bar than the lower applied pressure range (i.e. 12 to 14 bar. This research plays an important role by identifying the key parameters that could restore the flux of organically fouled NF membranes significantly.

  5. Chemical stability of levoglucosan: An isotopic perspective

    Science.gov (United States)

    Sang, X. F.; Gensch, I.; Kammer, B.; Khan, A.; Kleist, E.; Laumer, W.; Schlag, P.; Schmitt, S. H.; Wildt, J.; Zhao, R.; Mungall, E. L.; Abbatt, J. P. D.; Kiendler-Scharr, A.

    2016-05-01

    The chemical stability of levoglucosan was studied by exploring its isotopic fractionation during the oxidation by hydroxyl radicals. Aqueous solutions as well as mixed (NH4)2SO4-levoglucosan particles were exposed to OH. In both cases, samples experiencing different extents of processing were isotopically analyzed by Thermal Desorption-Gas Chromatography-Isotope Ratio Mass Spectrometry (TD-GC-IRMS). From the dependence of levoglucosan δ13C and concentration on the reaction extent, the kinetic isotope effect (KIE) of the OH oxidation reactions was determined to be 1.00187±0.00027 and 1.00229±0.00018, respectively. Both show good agreement within the uncertainty range. For the heterogeneous oxidation of particulate levoglucosan by gas-phase OH, a reaction rate constant of (2.67±0.03)·10-12 cm3 molecule-1S-1 was derived. The laboratory kinetic data, together with isotopic source and ambient observations, give information on the extent of aerosol chemical processing in the atmosphere.

  6. Thermal stability of nafion membranes under mechanical stress

    Energy Technology Data Exchange (ETDEWEB)

    Quintilii, M; Struis, R [Paul Scherrer Inst. (PSI), Villigen (Switzerland)

    1997-06-01

    The feasibility of adequately modified fluoro-ionomer membranes (NAFION{sup R}) is demonstrated for the selective separation of methanol synthesis products from the raw reactor gas at temperatures around 200{sup o}C. For an economically relevant application of this concept on a technical scale the Nafion membranes should be thin ({approx_equal}10 {mu}m) and thermally stable over a long period of time (1-2 years). In cooperation with industry (Methanol Casale SA, Lugano (CH)), we test the thermal stability of Nafion hollow fibers and supported Nafion thin sheet membranes at temperatures between 160 and 200{sup o}C under mechanical stress by applying a gas pressure difference over the membrane surface ({Delta}P{<=} 40 bar). Tests with the hollow fibers revealed that Nafion has visco-elastic properties. Tests with 50 {mu}m thin Nafion sheets supported by a porous metal carrier at 200{sup o}C and {Delta}P=39 bar showed no mechanical defects over a period of 92 days. (author) 5 figs., 4 refs.

  7. Chemically triggered ejection of membrane tubules controlled by intermonolayer friction.

    Science.gov (United States)

    Fournier, J-B; Khalifat, N; Puff, N; Angelova, M I

    2009-01-09

    We report a chemically driven membrane shape instability that triggers the ejection of a tubule growing exponentially toward a chemical source. The instability is initiated by a dilation of the exposed monolayer, which is coupled to the membrane spontaneous curvature and slowed down by intermonolayer friction. Our experiments are performed by local delivery of a basic pH solution to a giant vesicle. Quantitative fits of the data give an intermonolayer friction coefficient b approximately 2x10;{9} J s/m;{4}. The exponential growth of the tubule may be explained by a Marangoni stress yielding a pulling force proportional to its length.

  8. Chemical stability of high-temperature superconductors

    Science.gov (United States)

    Bansal, Narottam P.

    1992-01-01

    A review of the available studies on the chemical stability of the high temperature superconductors (HTS) in various environments was made. The La(1.8)Ba(0.2)CuO4 HTS is unstable in the presence of H2O, CO2, and CO. The YBa2Cu3O(7-x) superconductor is highly susceptible to degradation in different environments, especially water. The La(2-x)Ba(x)CuO4 and Bi-Sr-Ca-Cu-O HTS are relatively less reactive than the YBa2Cu3O(7-x). Processing of YBa2Cu3O(7-x) HTS in purified oxygen, rather than in air, using high purity noncarbon containing starting materials is recommended. Exposure of this HTS to the ambient atmosphere should also be avoided at all stages during processing and storage. Devices and components made out of these oxide superconductors would have to be protected with an impermeable coating of a polymer, glass, or metal to avoid deterioration during use.

  9. Stability of a chemically active floating disk

    Science.gov (United States)

    Vandadi, Vahid; Jafari Kang, Saeed; Rothstein, Jonathan; Masoud, Hassan

    2017-11-01

    We theoretically study the translational stability of a chemically active disk located at a flat liquid-gas interface. The initially immobile circular disk uniformly releases an interface-active agent that locally changes the surface tension and is insoluble in the bulk. If left unperturbed, the stationary disk remains motionless as the agent is discharged. Neglecting the inertial effects, we numerically test whether a perturbation in the translational velocity of the disk can lead to its spontaneous and self-sustained motion. Such a perturbation gives rise to an asymmetric distribution of the released factor that could trigger and sustain the Marangoni propulsion of the disk. An implicit Fourier-Chebyshev spectral method is employed to solve the advection-diffusion equation for the concentration of the active agent. The solution, given a linear equation of state for the surface tension, provides the shear stress distribution at the interface. This and the no-slip condition on the wetted surface of the disk are then used at each time step to semi-analytically determine the Stokes flow in the semi-infinite liquid layer. Overall, the findings of our investigation pave the way for pinpointing the conditions under which interface-bound active particles become dynamically unstable.

  10. Membrane-Organized Chemical Photoredox Systems

    Energy Technology Data Exchange (ETDEWEB)

    Hurst, James K.

    2014-09-18

    This project has three interrelated goals relevant to solar water photolysis, which are to develop: (1) vesicle-organized assemblies for H2 photoproduction that utilize pyrylium and structurally related compounds as combined photosensitizers and cyclic electroneutral transmembrane electron carriers; (2) transmembrane redox systems whose reaction rates can be modulated by light; and (3) homogeneous catalysts for water oxidation. . In area (1), initial efforts to photogenerate H2 from vectorially-organized vesicles containing occluded colloidal Pt and commonly available pyrylium ions as transmembrane redox mediators were unsuccessful. New pyrylium compounds with significantly lower reduction potentials have been synthesized to address this problem, their apparent redox potentials in functioning systems have been now evaluated by using a series of occluded viologens, and H2 photoproduction has been demonstrated in continuous illumination experiments. In area (2), spirooxazine-quinone dyads have been synthesized and their capacity to function as redox mediators across bilayer membranes has been evaluated through continuous photolysis and transient spectrophotometric measurements. Photoisomerization of the spiro moiety to the ring-open mero form caused net quantum yields to decrease significantly, providing a basis for photoregulation of transmembrane redox. Research on water oxidation (area 3) has been directed at understanding mechanisms of catalysis by cis,cis-[(bpy)2Ru(OH2)]2O4+ and related polyimine complexes. Using a variety of physical techniques, we have: (i) identified the redox state of the complex ion that is catalytically active; (ii) shown using 18O isotopic labeling that there are two reaction pathways, both of which involve participation of solvent H2O; and (iii) detected and characterized by EPR and resonance Raman spectroscopies new species which may be key intermediates in the catalytic cycle.

  11. Emerging trends in chemical separations with liquid membranes: an overview

    International Nuclear Information System (INIS)

    Shukla, J.P.

    1997-01-01

    It can be concluded that varied configurations of liquid membranes (LMs) will definitely play an important role in metal separations particularly in situations where other conventional chemical separation techniques fail to deliver goods. Potential areas include decontamination of biotoxic/ radioactive wastes, recovery of precious and strategic metals from lean/ extremely dilute solutions, add on to existing units, hydrometallurgy, etc

  12. Erythrocyte membrane stabilization effect and antioxidant activity of methyl methacrylate

    International Nuclear Information System (INIS)

    Popov, B.

    2004-01-01

    Methyl methacrylate (MMK) is a synthetic product with mild impact on human health that is not well studied on cellular basis. Here, human erythrocytes were used to investigate the effects MMK exerts on acid and heat-induced hemolysis. Biphasic effect of MMK was observed for acid-induced hemolysis; i.e., protection at low (0 - 0.05% v/v) and stimulation at higher (0.1- 0.4% v/v) concentrations. The maximal protective effect was produced at 0.03% (v/v). At this concentration MMK increased the temperatures of heat denaturation of erythrocyte membrane proteins, spectrin and integral proteins, by about 2 0 C and inhibited the heat-induced hemolysis by 20 %. This membrane stabilization effect of MMK is similar to that produced by some anti-inflammatory and antirheumatic drugs. The increased acid resistance possibly indicated anti-oxidant properties of MMK. The nonenzymatic antioxidant activity test evidenced that MMK has no superoxide dismutase-like activity but demonstrates strong catalase-like activity (about 900 kU/mmol at 0.05-0.1 mmol/l concentration). The results indicate that at low concentration MMK exerts benign effect on cellular membrane that could find therapeutic usage. (author)

  13. Semi-fluorinated sulfonated polyimide membranes with enhanced proton selectivity and stability for vanadium redox flow batteries

    International Nuclear Information System (INIS)

    Li, Jinchao; Liu, Suqin; He, Zhen; Zhou, Zhi

    2016-01-01

    A series of semi-fluorinated sulfonated polyimides (6F-SPIs) are designed and synthesized via a one-step high-temperature polycondensation reaction. The sulfonation degrees of 6F-SPIs are controlled through changing the ratio of sulfonated diamine to non-sulfonated diamine in the casting solution. The physico-chemical properties and single cell performance of 6F-SPI membranes are thoroughly evaluated and compared to a non-fluorinated SPI membrane (6H-SPI-50) and a Nafion 115 membrane. The results show that the designed 6F-SPI membrane with a 50% sulfonation degree (6F-SPI-50) possesses the highest proton selectivity (1.613 × 10 5 S min cm −3 ) among all tested membranes. Besides, the 6F-SPI-50 membrane exhibits a promising performance for vanadium redox flow batteries (VRFBs), showing higher coulombic efficiencies (96.90–99.20%) and energy efficiencies (88.25–64.80%) than the Nafion 115 membrane (with coulombic efficiencies of 90.60–96.70% and energy efficiencies of 81.04–60.10%) at the current densities ranging from 20 to 100 mA cm −2 . Moreover, the 6F-SPI-50 membrane shows excellent chemical stability in the VRFB system. This work paves the way for the development of a new class of 6F-SPI membranes for the VRFB application.

  14. Chemical Stability of Telavancin in Elastomeric Pumps☆

    Science.gov (United States)

    Sand, Patrick; Aladeen, Traci; Kirkegaard, Paul; LaChance, Dennis; Slover, Christine

    2015-01-01

    Background VIBATIV is a once-daily, injectable lipoglycopeptide antibiotic approved in the U.S. for the treatment of hospital-acquired and ventilator-associated bacterial pneumonia (HABP/VABP) caused by susceptible isolates of Staphylococcus aureus when alternative treatments are not suitable. In addition, VIBATIV is approved in the U.S. for the treatment of adult patients with complicated skin & skin structure infections (cSSSI) caused by susceptible isolates of Gram-positive bacteria, including Staphylococcus aureus, both methicillin-susceptible (MSSA) and methicillin-resistant (MRSA) strains. Objective To evaluate the chemical stability of telavancin (Vibativ; Theravance Biopharma US, Inc, Northbrook, Illinois), a lipoglycopeptide antibiotic with activity against methicillin-resistant Staphylococcus aureus, in 2 types of elastomeric pumps, the Intermate Infusion System (Baxter International Inc) and the Homepump Eclipse (I-Flow Corporation). Methods Different sizes of the Baxter (Ontario, Canada) (105 mL and 275 mL) and I-Flow (Stoughton, Massachusetts) (100 mL and 250 mL) pumps were compared with glass controls. The telavancin drug product was reconstituted and diluted to concentrations of 0.6 mg/mL and 8.0 mg/mL using either 0.9% saline, 5% dextrose in water, or sterilized water for injection (0.6 mg/mL telavancin) or saline (8.0 mg/mL telavancin) followed by Ringer’s Lactate solution. Pumps were filled and stored at 2°C to 8°C, protected from light. Aliquots from both pump types and for all telavancin reconstitution/dilution schemes and concentrations were taken over a period of 8 days and analyzed for appearance, pH, telavancin concentration and purity, and degradation products. Results The pH of all pump solutions remained consistent throughout the 8-day analysis period, within a range of 4.6 to 5.7 for the 0.6 mg/mL and 4.4 to 4.9 for the 8.0 mg/mL telavancin solutions. There was no significant change in the chromatographic purity for any of the pump

  15. Chemical Stability of Telavancin in Elastomeric Pumps.

    Science.gov (United States)

    Sand, Patrick; Aladeen, Traci; Kirkegaard, Paul; LaChance, Dennis; Slover, Christine

    2015-12-01

    VIBATIV is a once-daily, injectable lipoglycopeptide antibiotic approved in the U.S. for the treatment of hospital-acquired and ventilator-associated bacterial pneumonia (HABP/VABP) caused by susceptible isolates of Staphylococcus aureus when alternative treatments are not suitable. In addition, VIBATIV is approved in the U.S. for the treatment of adult patients with complicated skin & skin structure infections (cSSSI) caused by susceptible isolates of Gram-positive bacteria, including Staphylococcus aureus, both methicillin-susceptible (MSSA) and methicillin-resistant (MRSA) strains. To evaluate the chemical stability of telavancin (Vibativ; Theravance Biopharma US, Inc, Northbrook, Illinois), a lipoglycopeptide antibiotic with activity against methicillin-resistant Staphylococcus aureus, in 2 types of elastomeric pumps, the Intermate Infusion System (Baxter International Inc) and the Homepump Eclipse (I-Flow Corporation). Different sizes of the Baxter (Ontario, Canada) (105 mL and 275 mL) and I-Flow (Stoughton, Massachusetts) (100 mL and 250 mL) pumps were compared with glass controls. The telavancin drug product was reconstituted and diluted to concentrations of 0.6 mg/mL and 8.0 mg/mL using either 0.9% saline, 5% dextrose in water, or sterilized water for injection (0.6 mg/mL telavancin) or saline (8.0 mg/mL telavancin) followed by Ringer's Lactate solution. Pumps were filled and stored at 2°C to 8°C, protected from light. Aliquots from both pump types and for all telavancin reconstitution/dilution schemes and concentrations were taken over a period of 8 days and analyzed for appearance, pH, telavancin concentration and purity, and degradation products. The pH of all pump solutions remained consistent throughout the 8-day analysis period, within a range of 4.6 to 5.7 for the 0.6 mg/mL and 4.4 to 4.9 for the 8.0 mg/mL telavancin solutions. There was no significant change in the chromatographic purity for any of the pump solutions examined. All decreases in

  16. Partially Fluorinated Sulfonated Poly(ether amide Fuel Cell Membranes: Influence of Chemical Structure on Membrane Properties

    Directory of Open Access Journals (Sweden)

    Chulsung Bae

    2011-01-01

    Full Text Available A series of fluorinated sulfonated poly (ether amides (SPAs were synthesized for proton exchange membrane fuel cell applications. A polycondensation reaction of 4,4’-oxydianiline, 2-sulfoterephthalic acid monosodium salt, and tetrafluorophenylene dicarboxylic acids (terephthalic and isophthalic or fluoroaliphatic dicarboxylic acids produced SPAs with sulfonation degrees of 80–90%. Controlling the feed ratio of the sulfonated and unsulfonated dicarboxylic acid monomers afforded random SPAs with ion exchange capacities between 1.7 and 2.2 meq/g and good solubility in polar aprotic solvents. Their structures were characterized using NMR and FT IR spectroscopies. Tough, flexible, and transparent films were obtained with dimethylsulfoxide using a solution casting method. Most SPA membranes with 90% sulfonation degree showed high proton conductivity (>100 mS/cm at 80 °C and 100% relative humidity. Among them, two outstanding ionomers (ODA-STA-TPA-90 and ODA-STA-IPA-90 showed proton conductivity comparable to that of Nafion 117 between 40 and 80 °C. The influence of chemical structure on the membrane properties was systematically investigated by comparing the fluorinated polymers to their hydrogenated counterparts. The results suggest that the incorporation of fluorinated moieties in the polymer backbone of the membrane reduces water absorption. High molecular weight and the resulting physical entanglement of the polymers chains played a more important role in improving stability in water, however.

  17. Effect of Chemical Stabilizers in Silver Nanoparticle Suspensions on Nanotoxicity

    International Nuclear Information System (INIS)

    Bae, Eun Joo; Park, Hee Jin; Park, Jun Su; Yoon, Je Yong; Yi, Jong Heop; Kim, Young Hun; Choi, Kyung Hee

    2011-01-01

    Colloidal silver nanoparticles (AgNPs) have been commercialized as the typically stabilized form via the addition of a variety of surfactants or polymers. Herein, to examine the effects of stabilizing AgNPs in suspension, we modified the surface of bare AgNPs with four type of surfactants (NaDDBS, SDS, TW80, CTAB) and polymers (PVP, PAA, PAH, CMC). The modified AgNPs was applied to compare suspension stability and nanotoxicity test using Escherichia coli (E. coli) as a model organism. Modification of AgNPs surface using chemical stabilizer may be not related with molecular weight, but chemical structure such as ionic state and functional group of stabilizer. In this study, it is noteworthy that AgNPs modified with a cationic stabilizer (CTAB, PAH) were importantly toxic to E. coli, rather than anionic stabilizers (NaDDBS, SDS). Comparing similar anionic stabilizer, i.e., NaDDBS and SDS, the result showed that lipophilicity of chemical structure can affect on E. coli, because NaDDBS, which contains a lipophilic benzene ring, accelerated the cytotoxicity of AgNPs. Interestingly, none of the stabilizers tested, including biocompatible nonionic stabilizers (i.e., TW80 and cellulose) caused a reduction in AgNP toxicity. This showed that toxicity of AgNPs cannot be reduced using stabilizers

  18. Effect of Chemical Stabilizers in Silver Nanoparticle Suspensions on Nanotoxicity

    Energy Technology Data Exchange (ETDEWEB)

    Bae, Eun Joo; Park, Hee Jin; Park, Jun Su; Yoon, Je Yong; Yi, Jong Heop [Seoul National University, Seoul (Korea, Republic of); Kim, Young Hun [Kwangwoon University, Seoul (Korea, Republic of); Choi, Kyung Hee [National Institute of Environmental Research, Incheon (Korea, Republic of)

    2011-02-15

    Colloidal silver nanoparticles (AgNPs) have been commercialized as the typically stabilized form via the addition of a variety of surfactants or polymers. Herein, to examine the effects of stabilizing AgNPs in suspension, we modified the surface of bare AgNPs with four type of surfactants (NaDDBS, SDS, TW80, CTAB) and polymers (PVP, PAA, PAH, CMC). The modified AgNPs was applied to compare suspension stability and nanotoxicity test using Escherichia coli (E. coli) as a model organism. Modification of AgNPs surface using chemical stabilizer may be not related with molecular weight, but chemical structure such as ionic state and functional group of stabilizer. In this study, it is noteworthy that AgNPs modified with a cationic stabilizer (CTAB, PAH) were importantly toxic to E. coli, rather than anionic stabilizers (NaDDBS, SDS). Comparing similar anionic stabilizer, i.e., NaDDBS and SDS, the result showed that lipophilicity of chemical structure can affect on E. coli, because NaDDBS, which contains a lipophilic benzene ring, accelerated the cytotoxicity of AgNPs. Interestingly, none of the stabilizers tested, including biocompatible nonionic stabilizers (i.e., TW80 and cellulose) caused a reduction in AgNP toxicity. This showed that toxicity of AgNPs cannot be reduced using stabilizers.

  19. Chemical stability of oseltamivir in oral solutions.

    Science.gov (United States)

    Albert, K; Bockshorn, J

    2007-09-01

    The stability of oseltamivir in oral aqueous solutions containing the preservative sodium benzoate was studied by a stability indicating HPLC-method. The separation was achieved on a RP-18 ec column using a gradient of mobile phase A (aqueous solution of 50 mM ammonium acetate) and mobile phase B (60% (v/v) acetonitrile/40% (v/v) mobile phase A). The assay was subsequently validated according to the ICH guideline Q2(R1). The extemporaneously prepared "Oseltamivir Oral Solution 15 mg/ml for Adults or for Children" (NRF 31.2.) according to the German National Formulary ("Neues Rezeptur-Formularium") was stable for 84 days if stored under refrigeration. After storage at 25 degrees C the content of oseltamivir decreased to 98.4%. Considering the toxicological limit of 0.5% of the 5-acetylamino derivative (the so-called isomer I) the solution is stable for 46 days. Oseltamivir was less stable in a solution prepared with potable water instead of purified water. Due to an increasing pH the stability of this solution decreased to 14 days. Furthermore a white precipitate of mainly calcium phosphate was observed. The addition of 0.1% anhydrous citric acid avoided these problems and improved the stability of the solution prepared with potable water to 63 days. Sodium benzoate was stable in all oral solutions tested.

  20. Hydrothermal stability of silica, hybrid silica and Zr-doped hybrid silica membranes

    NARCIS (Netherlands)

    ten Hove, Marcel; Luiten-Olieman, Mieke W.J.; Huiskes, Cindy; Nijmeijer, Arian; Winnubst, Louis

    2017-01-01

    Hybrid silica membranes have demonstrated to possess a remarkable hydrothermal stability in pervaporation and gas separation processes allowing them to be used in industrial applications. In several publications the hydrothermal stability of pure silica or that of hybrid silica membranes are

  1. Chemical Stability of Telavancin in Elastomeric Pumps

    Directory of Open Access Journals (Sweden)

    Patrick Sand, MSc

    2015-12-01

    Conclusions: The results of this study indicate that telavancin remains chemically stable when diluted in the Intermate Infusion System and the Homepump Eclipse elastomeric pumps and stored at 2°C to 8°C for up to 8 days protected from light at the concentration range and dilution schemes evaluated.

  2. On the Chemical Stabilities of Ionic Liquids

    Directory of Open Access Journals (Sweden)

    Yen-Ho Chu

    2009-09-01

    Full Text Available Ionic liquids are novel solvents of interest as greener alternatives to conventional organic solvents aimed at facilitating sustainable chemistry. As a consequence of their unusual physical properties, reusability, and eco-friendly nature, ionic liquids have attracted the attention of organic chemists. Numerous reports have revealed that many catalysts and reagents were supported in the ionic liquid phase, resulting in enhanced reactivity and selectivity in various important reaction transformations. However, synthetic chemists cannot ignore the stability data and intermolecular interactions, or even reactions that are directly applicable to organic reactions in ionic liquids. It is becoming evident from the increasing number of reports on use of ionic liquids as solvents, catalysts, and reagents in organic synthesis that they are not totally inert under many reaction conditions. While in some cases, their unexpected reactivity has proven fortuitous and in others, it is imperative that when selecting an ionic liquid for a particular synthetic application, attention must be paid to its compatibility with the reaction conditions. Even though, more than 200 room temperature ionic liquids are known, only a few reports have commented their effects on reaction mechanisms or rate/stability. Therefore, rather than attempting to give a comprehensive overview of ionic liquid chemistry, this review focuses on the non-innocent nature of ionic liquids, with a decided emphasis to clearly illuminate the ability of ionic liquids to affect the mechanistic aspects of some organic reactions thereby affecting and promoting the yield and selectivity.

  3. On the chemical stabilities of ionic liquids.

    Science.gov (United States)

    Sowmiah, Subbiah; Srinivasadesikan, Venkatesan; Tseng, Ming-Chung; Chu, Yen-Ho

    2009-09-25

    Ionic liquids are novel solvents of interest as greener alternatives to conventional organic solvents aimed at facilitating sustainable chemistry. As a consequence of their unusual physical properties, reusability, and eco-friendly nature, ionic liquids have attracted the attention of organic chemists. Numerous reports have revealed that many catalysts and reagents were supported in the ionic liquid phase, resulting in enhanced reactivity and selectivity in various important reaction transformations. However, synthetic chemists cannot ignore the stability data and intermolecular interactions, or even reactions that are directly applicable to organic reactions in ionic liquids. It is becoming evident from the increasing number of reports on use of ionic liquids as solvents, catalysts, and reagents in organic synthesis that they are not totally inert under many reaction conditions. While in some cases, their unexpected reactivity has proven fortuitously advantageous in others is has been a problem, it is imperative that when selecting an ionic liquid for a particular synthetic application, attention be paid to its compatibility with the reaction conditions. Even though, more than 200 room temperature ionic liquids are known, only a few reports have commented their effects on reaction mechanisms or rate/stability. Therefore, rather than attempting to give a comprehensive overview of ionic liquid chemistry, this review focuses on the non-innocent nature of ionic liquids, with a decided emphasis to clearly illuminate the ability of ionic liquids to affect the mechanistic aspects of some organic reactions thereby affecting and promoting the yield and selectivity.

  4. Chemical Imaging of the Cell Membrane by NanoSIMS

    International Nuclear Information System (INIS)

    Weber, P.K.; Kraft, M.L.; Frisz, J.F.; Carpenter, K.J.; Hutcheon, I.D.

    2010-01-01

    The existence of lipid microdomains and their role in cell membrane organization are currently topics of great interest and controversy. The cell membrane is composed of a lipid bilayer with embedded proteins that can flow along the two-dimensional surface defined by the membrane. Microdomains, known as lipid rafts, are believed to play a central role in organizing this fluid system, enabling the cell membrane to carry out essential cellular processes, including protein recruitment and signal transduction. Lipid rafts are also implicated in cell invasion by pathogens, as in the case of the HIV. Therefore, understanding the role of lipid rafts in cell membrane organization not only has broad scientific implications, but also has practical implications for medical therapies. One of the major limitations on lipid organization research has been the inability to directly analyze lipid composition without introducing artifacts and at the relevant length-scales of tens to hundreds of nanometers. Fluorescence microscopy is widely used due to its sensitivity and specificity to the labeled species, but only the labeled components can be observed, fluorophores can alter the behavior of the lipids they label, and the length scales relevant to imaging cell membrane domains are between that probed by fluorescence resonance energy transfer (FRET) imaging (<10 nm) and the diffraction limit of light. Topographical features can be imaged on this length scale by atomic force microscopy (AFM), but the chemical composition of the observed structures cannot be determined. Immuno-labeling can be used to study the distribution of membrane proteins at high resolution, but not lipid composition. We are using imaging mass spectrometry by secondary ion mass spectrometry (SIMS) in concert with other high resolution imaging methods to overcome these limitations. The experimental approach of this project is to combine molecule-specific stable isotope labeling with high-resolution SIMS using a

  5. Removal of trace organic chemical contaminants by a membrane bioreactor.

    Science.gov (United States)

    Trinh, T; van den Akker, B; Stuetz, R M; Coleman, H M; Le-Clech, P; Khan, S J

    2012-01-01

    Emerging wastewater treatment processes such as membrane bioreactors (MBRs) have attracted a significant amount of interest internationally due to their ability to produce high quality effluent suitable for water recycling. It is therefore important that their efficiency in removing hazardous trace organic contaminants be assessed. Accordingly, this study investigated the removal of trace organic chemical contaminants through a full-scale, package MBR in New South Wales, Australia. This study was unique in the context of MBR research because it characterised the removal of 48 trace organic chemical contaminants, which included steroidal hormones, xenoestrogens, pesticides, caffeine, pharmaceuticals and personal care products (PPCPs). Results showed that the removal of most trace organic chemical contaminants through the MBR was high (above 90%). However, amitriptyline, carbamazepine, diazepam, diclofenac, fluoxetine, gemfibrozil, omeprazole, sulphamethoxazole and trimethoprim were only partially removed through the MBR with the removal efficiencies of 24-68%. These are potential indicators for assessing MBR performance as these chemicals are usually sensitive to changes in the treatment systems. The trace organic chemical contaminants detected in the MBR permeate were 1 to 6 orders of magnitude lower than guideline values reported in the Australian Guidelines for Water Recycling. The outcomes of this study enhanced our understanding of the levels and removal of trace organic contaminants by MBRs.

  6. A Mechanistic Study of Chemically Modified Inorganic Membranes for Gas and Liquid Separations

    Energy Technology Data Exchange (ETDEWEB)

    Way, J. Douglas [Colorado School of Mines, Golden, CO (United States). Dept. of Chemical Engineering

    2011-01-21

    This final report will summarize the progress made during the period August 1, 1993 - October 31, 2010 with support from DOE grant number DE-FG03-93ER14363. The objectives of the research have been to investigate the transport mechanisms in micro- and mesoporous, metal oxide membranes and to examine the relationship between the microstructure of the membrane, the membrane surface chemistry, and the separation performance of the membrane. Examples of the membrane materials under investigation are the microporous silica hollow fiber membrane manufactured by PPG Industries, chemically modified mesoporous oxide membranes, and polymer membranes containing microporous oxides (mixed matrix membranes). Analytical techniques such as NMR, FTIR and Raman spectroscopy, thermal analysis, and gas adsorption were used to investigate membrane microstructure and to probe the chemical interactions occurring at the gas-membrane interface.

  7. Membrane-stabilizing copolymers confer marked protection to dystrophic skeletal muscle in vivo

    Directory of Open Access Journals (Sweden)

    Evelyne M Houang

    Full Text Available Duchenne muscular dystrophy (DMD is a fatal disease of striated muscle deterioration. A unique therapeutic approach for DMD is the use of synthetic membrane stabilizers to protect the fragile dystrophic sarcolemma against contraction-induced mechanical stress. Block copolymer-based membrane stabilizer poloxamer 188 (P188 has been shown to protect the dystrophic myocardium. In comparison, the ability of synthetic membrane stabilizers to protect fragile DMD skeletal muscles has been less clear. Because cardiac and skeletal muscles have distinct structural and functional features, including differences in the mechanism of activation, variance in sarcolemma phospholipid composition, and differences in the magnitude and types of forces generated, we speculated that optimized membrane stabilization could be inherently different. Our objective here is to use principles of pharmacodynamics to evaluate membrane stabilization therapy for DMD skeletal muscles. Results show a dramatic differential effect of membrane stabilization by optimization of pharmacodynamic-guided route of poloxamer delivery. Data show that subcutaneous P188 delivery, but not intravascular or intraperitoneal routes, conferred significant protection to dystrophic limb skeletal muscles undergoing mechanical stress in vivo. In addition, structure-function examination of synthetic membrane stabilizers further underscores the importance of copolymer composition, molecular weight, and dosage in optimization of poloxamer pharmacodynamics in vivo.

  8. Chemical stabilization of porous silicon for enhanced biofunctionalization with immunoglobulin

    Directory of Open Access Journals (Sweden)

    Nelson Naveas, Vicente Torres Costa, Dario Gallach, Jacobo Hernandez-Montelongo, Raul Jose Martín Palma, Josefa Predenstinacion Garcia-Ruiz and Miguel Manso-Silván

    2012-01-01

    Full Text Available Porous silicon (PSi is widely used in biological experiments, owing to its biocompatibility and well-established fabrication methods that allow tailoring its surface. Nevertheless, there are some unresolved issues such as deciding whether the stabilization of PSi is necessary for its biological applications and evaluating the effects of PSi stabilization on the surface biofunctionalization with proteins. In this work we demonstrate that non-stabilized PSi is prone to detachment owing to the stress induced upon biomolecular adsorption. Biofunctionalized non-stabilized PSi loses the interference properties characteristic of a thin film, and groove-like structures resulting from a final layer collapse were observed by scanning electron microscopy. Likewise, direct PSi derivatization with 3-aminopropyl-triethoxysilane (APTS does not stabilize PSi against immunoglobulin biofunctionalization. To overcome this problem, we developed a simple chemical process of stabilizing PSi (CoxPSi for biological applications, which has several advantages over thermal stabilization (ToxPSi. The process consists of chemical oxidation in H2O2, surface derivatization with APTS and a curing step at 120 °C. This process offers integral homogeneous PSi morphology, hydrophilic surface termination (contact angle θ = 26° and highly efficient derivatized and biofunctionalized PSi surfaces (six times more efficient than ToxPSi. All these features are highly desirable for biological applications, such as biosensing, where our results can be used for the design and optimization of the biomolecular immobilization cascade on PSi surfaces.

  9. The thermomechanical stability of micro-solid oxide fuel cells fabricated on anodized aluminum oxide membranes

    Science.gov (United States)

    Kwon, Chang-Woo; Lee, Jae-Il; Kim, Ki-Bum; Lee, Hae-Weon; Lee, Jong-Ho; Son, Ji-Won

    2012-07-01

    The thermomechanical stability of micro-solid oxide fuel cells (micro-SOFCs) fabricated on an anodized aluminum oxide (AAO) membrane template is investigated. The full structure consists of the following layers: AAO membrane (600 nm)/Pt anode/YSZ electrolyte (900 nm)/porous Pt cathode. The utilization of a 600-nm-thick AAO membrane significantly improves the thermomechanical stability due to its well-known honeycomb-shaped nanopore structure. Moreover, the Pt anode layer deposited in between the AAO membrane and the YSZ electrolyte preserves its integrity in terms of maintaining the triple-phase boundary (TPB) and electrical conductivity during high-temperature operation. Both of these results guarantee thermomechanical stability of the micro-SOFC and extend the cell lifetime, which is one of the most critical issues in the fabrication of freestanding membrane-type micro-SOFCs.

  10. Stability of biogenic metal(loid) nanomaterials related to the colloidal stabilization theory of chemical nanostructures.

    Science.gov (United States)

    Piacenza, Elena; Presentato, Alessandro; Turner, Raymond J

    2018-02-25

    In the last 15 years, the exploitation of biological systems (i.e. plants, bacteria, mycelial fungi, yeasts, and algae) to produce metal(loid) (Me)-based nanomaterials has been evaluated as eco-friendly and a cost-effective alternative to the chemical synthesis processes. Although the biological mechanisms of biogenic Me-nanomaterial (Bio-Me-nanomaterials) production are not yet completely elucidated, a key advantage of such bio-nanostructures over those chemically synthesized is related to their natural thermodynamic stability, with several studies ascribed to the presence of an organic layer surrounding these Bio-Me-nanostructures. Different macromolecules (e.g. proteins, peptides, lipids, DNA, and polysaccharides) or secondary metabolites (e.g. flavonoids, terpenoids, glycosides, organic acids, and alkaloids) naturally produced by organisms have been indicated as main contributors to the stabilization of Bio-Me-nanostructures. Nevertheless, the chemical-physical mechanisms behind the ability of these molecules in providing stability to Bio-Me-nanomaterials are unknown. In this context, transposing the stabilization theory of chemically synthesized Me-nanomaterials (Ch-Me-nanomaterials) to biogenic materials can be used towards a better comprehension of macromolecules and secondary metabolites role as stabilizing agents of Bio-Me-nanomaterials. According to this theory, nanomaterials are generally featured by high thermodynamic instability in suspension, due to their high surface area and surface energy. This feature leads to the necessity to stabilize chemical nanostructures, even during or directly after their synthesis, through the development of (i) electrostatic, (ii) steric, or (iii) electrosteric interactions occurring between molecules and nanomaterials in suspension. Based on these three mechanisms, this review is focused on parallels between the stabilization of biogenic or chemical nanomaterials, suggesting which chemical-physical mechanisms may be

  11. Physical and chemical stability of pemetrexed in infusion solutions.

    Science.gov (United States)

    Zhang, Yanping; Trissel, Lawrence A

    2006-06-01

    Pemetrexed is a multitargeted, antifolate, antineoplastic agent that is indicated for single-agent use in locally advanced or metastatic non-small-cell lung cancer after prior chemotherapy and in combination with cisplatin for the treatment of malignant pleural mesothelioma not treatable by surgery. Currently, there is no information on the long-term stability of pemetrexed beyond 24 hours. To evaluate the longer-term physical and chemical stability of pemetrexed 2, 10, and 20 mg/mL in polyvinyl chloride (PVC) bags of dextrose 5% injection and NaCl 0.9% injection. Triplicate samples of pemetrexed were prepared in the concentrations and infusion solutions required. Evaluations for physical and chemical stability were performed initially and over 2 days at 23 degrees C protected from light and exposed to fluorescent light, and over 31 days of storage at 4 degrees C protected from light. Physical stability was assessed using turbidimetric and particulate measurement as well as visual observation. Chemical stability was evaluated by HPLC. All pemetrexed solutions remained chemically stable, with little or no loss of pemetrexed over 2 days at 23 degrees C, protected from light and exposed to fluorescent light, and over 31 days of storage at 4 degrees C, protected from light. The room temperature samples were physically stable throughout the 48 hour test period. However, pemetrexed admixtures developed large numbers of microparticulates during refrigerated storage exceeding 24 hours. Pemetrexed is chemically stable for 2 days at room temperature and 31 days refrigerated in dextrose 5% injection and NaCl 0.9% injection. However, substantial numbers of microparticulates may form in pemetrexed diluted in the infusion solutions in PVC bags, especially during longer periods of refrigerated storage. Limiting the refrigerated storage period to the manufacturer-recommended 24 hours will limit particulate formation.

  12. A New Class of Amphiphiles Bearing Rigid Hydrophobic Groups for Solubilization and Stabilization of Membrane Proteins

    DEFF Research Database (Denmark)

    Chae, Pil Seok; Rasmussen, Søren G F; Rana, Rohini R

    2012-01-01

    Non-traditional amphiphiles: Conferring aqueous solubility on membrane proteins generally requires the use of a detergent or other amphiphilic agent. A new class of amphiphiles was synthesized, based on steroidal lipophilic groups, and evaluated with several membrane proteins. The results show th...... that the new amphiphile, "glyco-diosgenin" (GDN; see figure), confers enhanced stability to a variety of membrane proteins in solution relative to popular conventional detergents, such as dodecylmaltoside (DDM)....

  13. Surface modification of titanium membrane by chemical vapor deposition and its electrochemical self-cleaning

    International Nuclear Information System (INIS)

    Li, X.W.; Li, J.X.; Gao, C.Y.; Chang, M.

    2011-01-01

    Membrane separation is applied widely in many fields, while concentration polarization and membrane fouling, limiting its promotion and application greatly, are the bottlenecks in membrane application. Among which, membrane fouling is irreversible, membrane must be periodically cleaned or even replaced to restore permeability. Membrane cleaning has become one of Key issues in membrane separation areas. Considering incomparable electrochemical advantages of boron-doped diamond (BDD) film electrode over conventional electrode, a new composite membrane Ti/BDD, made by depositing CVD (chemical vapor deposition) boron-doped diamond film on titanium(Ti) membrane to modify porous titanium surface, that can be cleaned electrochemically is proposed. Feasibility of its preparation and application is discussed in this paper. Results shows that based on the unique electrochemical properties of diamond, cleaning level of this composite Ti/BDD membrane is significantly increased, making membrane life and efficiency improved prominently.

  14. Surface modification of titanium membrane by chemical vapor deposition and its electrochemical self-cleaning

    Energy Technology Data Exchange (ETDEWEB)

    Li, X.W., E-mail: lynnww@sohu.com [School of Electronic and Information Engieering, Tianjin university, Tianjin, 300072 (China); School of Electronics Information Engieering, Tianjin University of Technology, Tianjin, 300384 (China); Li, J.X. [Tianjin Polytechnic University, Tianjin 300160 (China); Gao, C.Y. [Chinese Peoples Armed Police Forces Academy, Langfang 065000 (China); Chang, M. [School of Electronic and Information Engieering, Tianjin university, Tianjin, 300072 (China); School of Electronics Information Engieering, Tianjin University of Technology, Tianjin, 300384 (China)

    2011-10-15

    Membrane separation is applied widely in many fields, while concentration polarization and membrane fouling, limiting its promotion and application greatly, are the bottlenecks in membrane application. Among which, membrane fouling is irreversible, membrane must be periodically cleaned or even replaced to restore permeability. Membrane cleaning has become one of Key issues in membrane separation areas. Considering incomparable electrochemical advantages of boron-doped diamond (BDD) film electrode over conventional electrode, a new composite membrane Ti/BDD, made by depositing CVD (chemical vapor deposition) boron-doped diamond film on titanium(Ti) membrane to modify porous titanium surface, that can be cleaned electrochemically is proposed. Feasibility of its preparation and application is discussed in this paper. Results shows that based on the unique electrochemical properties of diamond, cleaning level of this composite Ti/BDD membrane is significantly increased, making membrane life and efficiency improved prominently.

  15. Rapid Production of a Porous Cellulose Acetate Membrane for Water Filtration Using Readily Available Chemicals

    Science.gov (United States)

    Kaiser, Adrian; Stark, Wendelin J.; Grass, Robert N.

    2017-01-01

    A chemistry laboratory experiment using everyday items and readily available chemicals is described to introduce advanced high school students and undergraduate college students to porous polymer membranes. In a three-step manufacturing process, a membrane is produced at room temperature. The filtration principle of the membrane is then…

  16. Ionic Liquid Confined in Mesoporous Polymer Membrane with Improved Stability for CO2/N2 Separation

    Directory of Open Access Journals (Sweden)

    Ming Tan

    2017-09-01

    Full Text Available Supported ionic liquid membranes (SILMs have a promising prospect of application in flue gas separation, owing to its high permeability and selectivity of CO2. However, existing SILMs have the disadvantage of poor stability due to the loss of ionic liquid from the large pores of the macroporous support. In this study, a novel SILM with high stability was developed by confining ionic liquid in a mesoporous polymer membrane. First, a mesoporous polymer membrane derived from a soluble, low-molecular-weight phenolic resin precursor was deposited on a porous Al2O3 support, and then 1-ethyl-3-methylimidazolium tetrafluoroborate ([emim][BF4] was immobilized inside mesopores of phenolic resin, forming the SILM under vacuum. Effects of trans-membrane pressure difference on the SILM separation performance were investigated by measuring the permeances of CO2 and N2. The SILM exhibits a high ideal CO2/N2 selectivity of 40, and an actual selectivity of approximately 25 in a mixed gas (50% CO2 and 50% N2 at a trans-membrane pressure difference of 2.5 bar. Compared to [emim][BF4] supported by polyethersulfone membrane with a pore size of around 0.45 μm, the [emim][BF4] confined in a mesoporous polymer membrane exhibits an improved stability, and its separation performance remained stable for 40 h under a trans-membrane pressure difference of 1.5 bar in a mixed gas before the measurement was intentionally stopped.

  17. [Pharmaceutical research progress of rhynchophylla based on chemical stability].

    Science.gov (United States)

    Hao, Bo; Yang, Xiu-Juan; Feng, Yi; Hong, Yan-Long

    2014-12-01

    Rhynchophylla is a Chinese herb commonly used in clinical practice. It's also the primary herb of some famous Chinese herbal compound such as Tianma Gouteng decoction, and Lingyang Gouteng decoction. According the record from many previous materia medica literatures, rhynchophylla should be added later during decoction. Pharmaceutical research showed that rhynchophylla alkaloids were not stable. Which has resulted in many problems in the research and its application. For example, there was not a quantitative determination method in "Chinese Pharmacopoeia" of past and present versions, which seriously impacted its quality control and product application. Firstly, records from previous materia medica literatures and "Chinese Pharmacopoeia" were systematically sorted based on the chemical stability of rhynchophylla. Secondly, pharmaceutical research including chemical compositions and their stability, pharmacological effects, extraction process and quality analysis, was reviewed after reference of literatures published at home and abroad in recent decades. Positive reference and evidence for further research and development of rhynchophylla will be provided in the article.

  18. Effect of operation parameters on the flux stabilization of gravity-driven membrane (GDM) filtration system for decentralized water supply.

    Science.gov (United States)

    Tang, Xiaobin; Ding, An; Qu, Fangshu; Jia, Ruibao; Chang, Haiqing; Cheng, Xiaoxiang; Liu, Bin; Li, Guibai; Liang, Heng

    2016-08-01

    A pilot-scale gravity-driven membrane (GDM) filtration system under low gravitational pressure without any pre-treatment, backwash, flushing, or chemical cleaning was carried out to investigate the effect of operation parameters (including operation pressure, aeration mode, and intermittent filtration) on the effluent quality and permeability development. The results revealed that GDM system exhibited an efficient performance for the removal of suspended substances and organic compounds. The stabilization of flux occurred and the average values of stable flux were 6.6, 8.1, and 8.6 Lm(-2) h(-1) for pressures of 65, 120, and 200 mbar, respectively. In contrast, flux stabilization was not observed under continuous and intermittent aeration conditions. However, aeration (especially continuous aeration) was effective to improve flux and alleviate membrane fouling during 1-month operation. Moreover, intermittent filtration would influence the stabilization of permeate flux, resulting in a higher stable flux (ranging from 6 to 13 Lm(-2) h(-1)). The stable flux significantly improved with the increase of intermittent period. Additionally, GDM systems exhibited an efficient recovery of flux after simple physical cleaning and the analyses of resistance reversibility demonstrated that most of the total resistance was hydraulic reversible resistance (50-75 %). Therefore, it is expected that the results of this study can develop strategies to increase membrane permeability and reduce energy consumption in GDM systems for decentralized water supply.

  19. Giant Plasma Membrane Vesicles: An Experimental Tool for Probing the Effects of Drugs and Other Conditions on Membrane Domain Stability.

    Science.gov (United States)

    Gerstle, Zoe; Desai, Rohan; Veatch, Sarah L

    2018-01-01

    Giant plasma membrane vesicles (GPMVs) are isolated directly from living cells and provide an alternative to vesicles constructed of synthetic or purified lipids as an experimental model system for use in a wide range of assays. GPMVs capture much of the compositional protein and lipid complexity of intact cell plasma membranes, are filled with cytoplasm, and are free from contamination with membranes from internal organelles. GPMVs often exhibit a miscibility transition below the growth temperature of their parent cells. GPMVs labeled with a fluorescent protein or lipid analog appear uniform on the micron-scale when imaged above the miscibility transition temperature, and separate into coexisting liquid domains with differing membrane compositions and physical properties below this temperature. The presence of this miscibility transition in isolated GPMVs suggests that a similar phase-like heterogeneity occurs in intact plasma membranes under growth conditions, albeit on smaller length scales. In this context, GPMVs provide a simple and controlled experimental system to explore how drugs and other environmental conditions alter the composition and stability of phase-like domains in intact cell membranes. This chapter describes methods to generate and isolate GPMVs from adherent mammalian cells and to interrogate their miscibility transition temperatures using fluorescence microscopy. © 2018 Elsevier Inc. All rights reserved.

  20. The impact of chemical cleaning on separation efficiency and properties of reverse osmosis membrane

    KAUST Repository

    Baatiyyah, Hani

    2018-04-01

    One of most major concerns from both cost-effective and technical point of view in membrane process industry is membrane cleaning. The aim of the project was to investigate the variations in membrane surface properties and separation efficiency of reverse osmosis membrane. Compativtive analysis have to be performed on four RO membrane before and after exposing the virgin membrane into chemical cleaning to identify and analysis the impact of the chemical cleaning on the performance of RO membrane. Commerical chemical cleaning used in this project were caustic and acidic cleaning agent. The project’s aim is the investigation of simulation software’s precision for the four membranes performance projection at different conditions of the feed water. The assessment of the membranes performance was done in the Innovation Cluster at pilot plant that was industrial in size. The main commercial elements used were the thin-film composite membranes with a spiral-wound of 8-inch polyamide. Ultrafiltration (UF) and seawater RO membrane pretreatment process was done for the red sea sourced feed water. A pressure vessel dimensioned at 8-inch was operated in conjunction with an individual element at 8 -20 m3/hr feed flow rate, with an 8 to 12 % recovery and an average 35,000-42,000 mg/L of total dissolved solids (TDS) composition for the feed water. To achieve the project’s aim in assessing the membranes, three phase experimental stages were completed. The membranes performance was assessed in terms of their water flux, salt rejection, boron rejection, bicarbonate rejection and permeate quality. In addition, the membrane surfaces were characterized after exposing the fresh membranes with a chemical cleaning reagent. The experimental results showed an increase in both permeate flow and salt passage for all studied elements. The changes in the membranes performance were systematically explained based on the changes in the charge density and chemical structure of the membranes

  1. The Acinar Cage: Basement Membranes Determine Molecule Exchange and Mechanical Stability of Human Breast Cell Acini.

    Directory of Open Access Journals (Sweden)

    Aljona Gaiko-Shcherbak

    Full Text Available The biophysical properties of the basement membrane that surrounds human breast glands are poorly understood, but are thought to be decisive for normal organ function and malignancy. Here, we characterize the breast gland basement membrane with a focus on molecule permeation and mechanical stability, both crucial for organ function. We used well-established and nature-mimicking MCF10A acini as 3D cell model for human breast glands, with ether low- or highly-developed basement membrane scaffolds. Semi-quantitative dextran tracer (3 to 40 kDa experiments allowed us to investigate the basement membrane scaffold as a molecule diffusion barrier in human breast acini in vitro. We demonstrated that molecule permeation correlated positively with macromolecule size and intriguingly also with basement membrane development state, revealing a pore size of at least 9 nm. Notably, an intact collagen IV mesh proved to be essential for this permeation function. Furthermore, we performed ultra-sensitive atomic force microscopy to quantify the response of native breast acini and of decellularized basement membrane shells against mechanical indentation. We found a clear correlation between increasing acinar force resistance and basement membrane formation stage. Most important native acini with highly-developed basement membranes as well as cell-free basement membrane shells could both withstand physiologically relevant loads (≤ 20 nN without loss of structural integrity. In contrast, low-developed basement membranes were significantly softer and more fragile. In conclusion, our study emphasizes the key role of the basement membrane as conductor of acinar molecule influx and mechanical stability of human breast glands, which are fundamental for normal organ function.

  2. Physical and chemical stability of different formulations with superoxide dismutase.

    Science.gov (United States)

    Di Mambro, V M; Campos, P M B G Maia; Fonseca, M J V

    2004-10-01

    Topical formulations with superoxide dismutase (SOD), a scavenger of superoxide radicals, have proved to be effective against some skin diseases. Nevertheless, formulations with proteins are susceptible to both chemical and physical instability. Three different formulations (anionic and non-ionic gel and emulsion) were developed and supplemented with SOD in order to determine the most stable formulation that would maintain SOD activity. Physical stability was evaluated by assessing the rheological behavior of the formulations stored at room temperature, 37 and 45 degrees C. Chemical stability was evaluated by the measurement of enzymatic activity in the formulations stored at room temperature and at 45 degrees C. Formulations showed a flow index less than one, characterizing pseudoplastic behavior. There was no significant difference in initial values of flow index, tixotropy or minimum apparent viscosity. Neither gel showed significant changes in minimum apparent viscosity concerning storage time or temperature, as well, SOD presence and its activity. The emulsion showed decreased viscosity by the 28th day, but no significant changes concerning storage temperature or SOD presence, although it showed a decreased activity. The addition of SOD to the formulations studied did not affect their physical stability but gel formulations seem to be better bases for enzyme addition.

  3. Chemical synthesis and stabilization of magnesium substituted brushite

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Donghyun [Department of Biomedical Engineering, Chung-Ang University, 221 Heukseok-Dong, Dongjak-Gu, Seoul 156-756 (Korea, Republic of); Kumta, Prashant N., E-mail: pkumta@pitt.edu [Department of Bioengineering, University of Pittsburgh, Pittsburgh, PA 15260 (United States); Department of Mechanical Engineering and Materials Sceince, University of Pittsburgh, Pittsburgh, PA 15260 (United States); Department of Chemical and Petroleum Engineering, University of Pittsburgh, Pittsburgh, PA 15260 (United States)

    2010-08-30

    Hydroxyapatite (Ca{sub 10}(PO{sub 4}){sub 6}(OH){sub 2}) is the most ubiquitous calcium phosphate phase used in implant coatings and more recently in gene/drug delivery applications due to its chemical stability under normal physiological conditions (37 deg. C, pH {approx} 7.5, 1 atm.). However, different calcium phosphate phases, such as brushite (CaH(PO{sub 4}){center_dot}2(H{sub 2}O)) and tricalcium phosphate (Ca{sub 3}(PO{sub 4}){sub 2}) which are thermodynamically unstable under physiological conditions are also being explored for biomedical applications. One way of stabilizing these phases under physiological conditions is to introduce magnesium to substitute for calcium in the brushite lattice. The role of magnesium as a stabilizing agent for synthesizing brushite under physiological conditions at room temperature has been studied. Chemical analysis, Fourier transform infrared spectroscopy and X-ray diffraction have also been conducted to validate the formation of magnesium substituted brushite under physiological conditions.

  4. Stability and structure of the membrane protein transporter Ffh is modulated by substrates and lipids

    DEFF Research Database (Denmark)

    Reinau, Marika Ejby; Otzen, Daniel

    2009-01-01

    the apoprotein. Escherichia coli lipid and DOPG (and to a smaller extent DOPC) increase Ffh's α-helical content, possibly related to Ffh's role in guiding membrane proteins to the membrane. Binding is largely mediated by electrostatic interactions but does not protect Ffh against trypsinolysis. We conclude...... that Ffh is a structurally flexible and dynamic protein whose stability is significantly modulated by the environment. © 2009 Elsevier Inc. All rights reserved....

  5. Molecular View of Cholesterol Flip-Flop and Chemical Potential in Different Membrane Environments

    NARCIS (Netherlands)

    Bennett, W. F. Drew; MacCallum, Justin L.; Hinner, Marlon J.; Marrink, Siewert J.; Tieleman, D. Peter

    2009-01-01

    The relative stability of cholesterol in cellular membranes and the thermodynamics of fluctuations from equilibrium have important consequences for sterol trafficking and lateral domain formation. We used molecular dynamics computer simulations to investigate the partitioning of cholesterol in a

  6. Chemically stabilized epitaxial wurtzite-BN thin film

    Science.gov (United States)

    Vishal, Badri; Singh, Rajendra; Chaturvedi, Abhishek; Sharma, Ankit; Sreedhara, M. B.; Sahu, Rajib; Bhat, Usha; Ramamurty, Upadrasta; Datta, Ranjan

    2018-03-01

    We report on the chemically stabilized epitaxial w-BN thin film grown on c-plane sapphire by pulsed laser deposition under slow kinetic condition. Traces of no other allotropes such as cubic (c) or hexagonal (h) BN phases are present. Sapphire substrate plays a significant role in stabilizing the metastable w-BN from h-BN target under unusual PLD growth condition involving low temperature and pressure and is explained based on density functional theory calculation. The hardness and the elastic modulus of the w-BN film are 37 & 339 GPa, respectively measured by indentation along direction. The results are extremely promising in advancing the microelectronic and mechanical tooling industry.

  7. Color stabilization of red wines. A chemical and colloidal approach.

    Science.gov (United States)

    Alcalde-Eon, Cristina; García-Estévez, Ignacio; Puente, Victor; Rivas-Gonzalo, Julián C; Escribano-Bailón, M Teresa

    2014-07-23

    The effects of cold treatment and time on CIELAB color parameters and on anthocyanin and anthocyanin-derived pigments composition have been evaluated as has been the effectiveness of either an enological tannin or a mannoprotein (M) on their stabilization. With respect to color, hue (hab) was increased in the wines treated with both enological products. Furthermore, the color changes induced by cold treatment were lessened by the addition of these two enological products, although the protective effect was higher for the wines treated with M. The pigment analysis revealed higher percentages of anthocyanin-derived pigments in tannin and M-treated samples (in both cold treated and not) in relation to control ones. The addition of the enological tannin may favor the synthesis of anthocyanin-derived pigments, which are chemically more stable than native anthocyanins, whereas M seems to stabilize anthocyanin-derived pigments from a colloidal point of view, avoiding their aggregation and further precipitation.

  8. Aquaporin based biomimetic membrane in forward osmosis: Chemical cleaning resistance and practical operation

    KAUST Repository

    Li, Zhenyu

    2017-07-27

    Aquaporin plays a promising role in fabricating high performance biomimetic forward osmosis (FO) membranes. However, aquaporin as a protein also has a risk of denaturation caused by various chemicals, resulting in a possible decay of membrane performance. The present study tested a novel aquaporin based biomimetic membrane in simulated membrane cleaning processes. The effects of cleaning agents on water flux and salt rejection were evaluated. The membrane showed a good resistance to the chemical agents. The water flux after chemical cleaning showed significant increases, particularly after cleaning with NaOCl and Alconox. Changes in the membrane structure and increased hydrophilicity in the surrounding areas of the aquaporin may be accountable for the increase in water permeability. The membrane shows stable salt rejection up to 99% after all cleaning agents were tested. A 15-day experiment with secondary wastewater effluent as the feed solution and seawater as the draw solution showed a stable flux and high salt rejection. The average rejection of the dissolved organic carbon from wastewater after the 15-day test was 90%. The results demonstrated that the aquaporin based biomimetic FO membrane exhibits chemical resistance for most agents used in membrane cleaning procedures, maintaining a stable flux and high salt rejection.

  9. Aquaporin based biomimetic membrane in forward osmosis: Chemical cleaning resistance and practical operation

    KAUST Repository

    Li, Zhenyu; Valladares Linares, Rodrigo; Bucs, Szilard; Fortunato, Luca; Hé lix-Nielsen, Claus; Vrouwenvelder, Johannes S.; Ghaffour, NorEddine; Leiknes, TorOve; Amy, Gary

    2017-01-01

    Aquaporin plays a promising role in fabricating high performance biomimetic forward osmosis (FO) membranes. However, aquaporin as a protein also has a risk of denaturation caused by various chemicals, resulting in a possible decay of membrane performance. The present study tested a novel aquaporin based biomimetic membrane in simulated membrane cleaning processes. The effects of cleaning agents on water flux and salt rejection were evaluated. The membrane showed a good resistance to the chemical agents. The water flux after chemical cleaning showed significant increases, particularly after cleaning with NaOCl and Alconox. Changes in the membrane structure and increased hydrophilicity in the surrounding areas of the aquaporin may be accountable for the increase in water permeability. The membrane shows stable salt rejection up to 99% after all cleaning agents were tested. A 15-day experiment with secondary wastewater effluent as the feed solution and seawater as the draw solution showed a stable flux and high salt rejection. The average rejection of the dissolved organic carbon from wastewater after the 15-day test was 90%. The results demonstrated that the aquaporin based biomimetic FO membrane exhibits chemical resistance for most agents used in membrane cleaning procedures, maintaining a stable flux and high salt rejection.

  10. Cetamolol: a new cardioselective beta-adrenoceptor blocking agent without membrane-stabilizing activity.

    Science.gov (United States)

    Beaulieu, G; Jaramillo, J; Cummings, J R

    1984-03-01

    Cetamolol, a new beta-adrenoceptor blocker with partial agonist activity and cardioselectivity, was studied in vivo to determine its membrane-stabilizing effects. Comparisons were carried out with atenolol, pindolol, practolol, propranolol, timolol, dexpropranolol, lidocaine, and procaine. The following results indicated that cetamolol lacked membrane-stabilizing activity: (i) failure to cause local anesthesia on the rabbit cornea and motor nerve of the rat tail; (ii) ineffectiveness in reversing ventricular arrhythmias induced by coronary artery litigation in dogs; (iii) failure to reduce cardiac automaticity in catecholamine-depleted dogs as determined by the rate of a subatrial rhythm during ventricular (vagal) escape; and (iv) lack of a significant increase in atrioventricular conduction time in vagotomized or atropinized dogs in contrast to the effect in normal dogs indicating a reflex effect of cetamolol. Other results include a restoration of sinus rhythm in dogs with ventricular tachycardia induced by ouabain, and a dose-related decline in the force of cardiac contraction in anesthetized dogs at doses from 3 to 15 mg/kg, which occurred after an initial increase in force owing to intrinsic sympathomimetic activity. Although the mechanisms for the latter two effects are not clear at this time, explanations other than membrane-stabilizing activity have been considered in view of the other findings. It is concluded that cetamolol lacks membrane-stabilizing activity even at inordinately high doses.

  11. Enhanced thermal stability of the thylakoid membranes from spruce. A comparison with selected angiosperms

    Czech Academy of Sciences Publication Activity Database

    Karlický, Václav; Kurasová, Irena; Ptáčková, B.; Večeřová, Kristýna; Urban, Otmar; Špunda, Vladimír

    2016-01-01

    Roč. 130, 1-3 (2016), s. 357-371 ISSN 0166-8595 R&D Projects: GA MŠk(CZ) LO1415; GA ČR GA13-28093S Institutional support: RVO:67179843 Keywords : Norway spruce * Thermal stability * Circular dichroism * Photosystem II organization * Thylakoid membrane Subject RIV: ED - Physiology Impact factor: 3.864, year: 2016

  12. Aquaporin based biomimetic membrane in forward osmosis: Chemical cleaning resistance and practical operation

    DEFF Research Database (Denmark)

    Li, Zhenyu; Linares, Rodrigo Valladares; Bucs, Szilard

    2017-01-01

    Aquaporin plays a promising role in fabricating high performance biomimetic forward osmosis (FO) membranes. However, aquaporin as a protein also has a risk of denaturation caused, by various chemicals, resulting in a possible decay of membrane performance. The present study tested a novel aquaporin...

  13. Aquaporin based biomimetic membrane in forward osmosis: Chemical cleaning resistance and practical operation

    DEFF Research Database (Denmark)

    Li, Zhenyu; Linares, Rodrigo Valladares; Bucs, Szilard

    2017-01-01

    Aquaporin plays a promising role in fabricating high performance biomimetic forward osmosis (FO) membranes. However, aquaporin as a protein also has a risk of denaturation caused, by various chemicals, resulting in a possible decay of membrane performance. The present study tested a novel aquapor...

  14. The Chemical Potential of Plasma Membrane Cholesterol: Implications for Cell Biology.

    Science.gov (United States)

    Ayuyan, Artem G; Cohen, Fredric S

    2018-02-27

    Cholesterol is abundant in plasma membranes and exhibits a variety of interactions throughout the membrane. Chemical potential accounts for thermodynamic consequences of molecular interactions, and quantifies the effective concentration (i.e., activity) of any substance participating in a process. We have developed, to our knowledge, the first method to measure cholesterol chemical potential in plasma membranes. This was accomplished by complexing methyl-β-cyclodextrin with cholesterol in an aqueous solution and equilibrating it with an organic solvent containing dissolved cholesterol. The chemical potential of cholesterol was thereby equalized in the two phases. Because cholesterol is dilute in the organic phase, here activity and concentration were equivalent. This equivalence allowed the amount of cholesterol bound to methyl-β-cyclodextrin to be converted to cholesterol chemical potential. Our method was used to determine the chemical potential of cholesterol in erythrocytes and in plasma membranes of nucleated cells in culture. For erythrocytes, the chemical potential did not vary when the concentration was below a critical value. Above this value, the chemical potential progressively increased with concentration. We used standard cancer lines to characterize cholesterol chemical potential in plasma membranes of nucleated cells. This chemical potential was significantly greater for highly metastatic breast cancer cells than for nonmetastatic breast cancer cells. Chemical potential depended on density of the cancer cells. A method to alter and fix the cholesterol chemical potential to any value (i.e., a cholesterol chemical potential clamp) was also developed. Cholesterol content did not change when cells were clamped for 24-48 h. It was found that the level of activation of the transcription factor STAT3 increased with increasing cholesterol chemical potential. The cholesterol chemical potential may regulate signaling pathways. Copyright © 2018. Published by

  15. Examination of lignocellulosic fibers for chemical, thermal, and separations properties: Addressing thermo-chemical stability issues

    Science.gov (United States)

    Johnson, Carter David

    Natural fiber-plastic composites incorporate thermoplastic resins with fibrous plant-based materials, sometimes referred to as biomass. Pine wood mill waste has been the traditional source of natural fibrous feedstock. In anticipation of a waste wood shortage other fibrous biomass materials are being investigated as potential supplements or replacements. Perennial grasses, agricultural wastes, and woody biomass are among the potential source materials. As these feedstocks share the basic chemical building blocks; cellulose, hemicellulose, and lignin, they are collectively called lignocellulosics. Initial investigation of a number of lignocellulosic materials, applied to fiber-plastic composite processing and material testing, resulted in varied results, particularly response to processing conditions. Less thermally stable lignocellulosic filler materials were physically changed in observable ways: darkened color and odor. The effect of biomass materials' chemical composition on thermal stability was investigated an experiment involving determination of the chemical composition of seven lignocellulosics: corn hull, corn stover, fescue, pine, soy hull, soy stover, and switchgrass. These materials were also evaluated for thermal stability by thermogravimetric analysis. The results of these determinations indicated that both chemical composition and pretreatment of lignocellulosic materials can have an effect on their thermal stability. A second study was performed to investigate what effect different pretreatment systems have on hybrid poplar, pine, and switchgrass. These materials were treated with hot water, ethanol, and a 2:1 benzene/ethanol mixture for extraction times of: 1, 3, 6, 12, and 24 hours. This factorial experiment demonstrated that both extraction time and medium have an effect on the weight percent of extractives removed from all three material types. The extracted materials generated in the above study were then subjected to an evaluation of thermal

  16. Physiological levels of diacylglycerols in phospholipid membranes induce membrane fusion and stabilize inverted phases

    International Nuclear Information System (INIS)

    Siegel, D.P.; Banschbach, J.; Alford, D.; Ellens, H.; Lis, L.J.; Quinn, P.J.; Yeagle, P.L.; Bentz, J.

    1989-01-01

    In a previous paper, it was shown that liposome fusion rates are substantially enhanced under the same conditions which induce isotropic 31 P NMR resonances in multilamellar dispersions of the same lipid. Both of these phenomena occur within the same temperature interval, ΔT I , below the L α /H II phase transition temperature, T H . T H and ΔT I can be extremely sensitive to the lipid composition. The present work shows that 2 mol % of diacylglycerols like those produced by the phosphatidylinositol cycle in vivo can lower T H , ΔT I , and the temperature for fast membrane fusion by 15-20 degree C. N-Monomethylated dioleoylphosphatidylethanolamine is used as a model system. These results show that physiological levels of diacylglycerols can substantially increase the susceptibility of phospholipid membranes to fusion. This suggests that, in addition to their role in protein kinase C activation, diacylglycerols could play a more direct role in the fusion event during stimulus-exocytosis coupling in vivo

  17. Chemical stability of reactive skin decontamination lotion (RSDL®).

    Science.gov (United States)

    Bogan, R; Maas, H J; Zimmermann, T

    2018-09-01

    Reactive Skin Decontamination Lotion (RSDL ® ) is used for the decontamination of Chemical Warfare Agents and Toxic Industrial Compounds after dermal exposure. It has to be stockpiled over a long period and is handled in all climatic zones. Therefore stability is an essential matter of concern. In this work we describe a study to the chemical stability of RSDL ® as basis for an estimation of shelf life. We analysed RSDL ® for the active ingredient 2,3-butandione monoxime (diacetylmonooxime, DAM), the putative degradation product dimethylglyoxime (DMG) and unknown degradation products by means of a reversed phase high pressure liquid chromatography (HPLC). Calculations were done according to the Arrhenius equation. Based on the temperature dependent rate constants, the time span was calculated, until defined threshold values for DAM and DMG subject to specification and valid regulations were exceeded. The calculated data were compared to the ones gathered from stockpiled samples and samples exposed during foreign mission. The decline of DAM followed first order kinetics, while formation of DMG could be described by zero order kinetics. The rate constants were distinctively temperature dependent. Calculated data were in good accordance to the measured ones from stockpile and mission. Based on a specified acceptable DAM-content of 90% and a valid threshold value of 0.1% (w/w) for the degradation product DMG, RSDL ® proved to be stable for at least four years if stored at the recommended conditions of 15°C-30°C. If continuously stored at higher temperatures shelf life will decrease markedly. Therefore RSDL ® is an object for risk orientated quality monitoring during storage. Copyright © 2017 Elsevier B.V. All rights reserved.

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

    International Nuclear Information System (INIS)

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

    1981-01-01

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

  19. Effect of crosslinking on the physico-chemical properties of radiation grafted PEM fuel cell membranes

    International Nuclear Information System (INIS)

    Mohamed Mahmoud Nasef; Hamdani Saidi

    2006-01-01

    The effect of crosslinking on the physico-chemical properties of radiation grafted proton conducting membranes (PFA-g-PSSA) was investigated. The membranes were prepared by radiation induced grafting of styrene/divinylbenzene (DVB) mixtures onto poly (tetrafluoroethylene-co-perfluorovinyl either) (PFA) films followed by sulfonation reactions. The variation of DVB content in the grafting mixture was in the range of 1-4 vol %. The equivalent weight, swelling, behavior and the proton conductivity of crosslinked membranes having equal degrees of grafting prepared found to be dependent predominantly on the level of crosslinking. The obtained membranes were found to posses a good combination of physico-chemical properties that is matching the commercial Nation 117 membranes

  20. Ceramic membrane fouling during ultrafiltration of oil/water emulsions: roles played by stabilization surfactants of oil droplets.

    Science.gov (United States)

    Lu, Dongwei; Zhang, Tao; Ma, Jun

    2015-04-07

    Oil/water (O/W) emulsion stabilized by surfactants is the part of oily wastewater that is most difficult to handle. Ceramic membrane ultrafiltration presently is an ideal process to treat O/W emulsions. However, little is known about the fouling mechanism of the ceramic membrane during O/W emulsion treatment. This paper investigated how stabilization surfactants of O/W emulsions influence the irreversible fouling of ceramic membranes during ultrafiltration. An unexpected phenomenon observed was that irreversible fouling was much less when the charge of the stabilization surfactant of O/W emulsions is opposite to the membrane. The less ceramic membrane fouling in this case was proposed to be due to a synergetic steric effect and demulsification effect which prevented the penetration of oil droplets into membrane pores and led to less pore blockage. This proposed mechanism was supported by cross section images of fouled and virgin ceramic membranes taken with scanning electron microscopy, regression results of classical fouling models, and analysis of organic components rejected by the membrane. Furthermore, this mechanism was also verified by the existence of a steric effect and demulsification effect. Our finding suggests that ceramic membrane oppositely charged to the stabilization surfactant should be applied in ultrafiltration of O/W emulsions to alleviate irreversible membrane fouling. It could be a useful rule for ceramic membrane ultrafiltration of oily wastewater.

  1. Analysis of hybrid membrane and chemical absorption systems for CO2 capture

    International Nuclear Information System (INIS)

    Binns, Michael; Oh, Se-Young; Kwak, Dong-Hun; Kim, Jin-Kuk

    2015-01-01

    Amine-based absorption of CO 2 is currently the industry standard technology for capturing CO 2 emitted from power plants, refineries and other large chemical plants. However, more recently there have been a number of competing technologies under consideration, including the use of membranes for CO 2 separation and purification. We constructed and analyzed two different hybrid configurations combining and connecting chemical absorption with membrane separation. For a particular flue gas which is currently treated with amine-based chemical absorption at a pilot plant we considered and tested how membranes could be integrated to improve the performance of the CO 2 capture. In particular we looked at the CO 2 removal efficiency and the energy requirements. Sensitivity analysis was performed varying the size of the membranes and the solvent flow rate

  2. Polypropylene Track Membranes for Mikro and Ultrafiltration of Chemically Aggressive Agents

    CERN Document Server

    Kravets, L I; Apel, P Yu

    2000-01-01

    A production process for track membranes on the basis of chemically resistant polymer polypropylene has been developed. Research in all stages of the formation of the polypropylene track membranes has been conducted: the main principles of the process of chemical etching of polypropylene irradiated with accelerated ions have been investigated, the most effective structure of the etchant for a selective etching of the heavy ion tracks has been selected, the parameters of etching have been optimized. A method for sensibilization of latent tracks in polypropylene by effect of solvents has been developed. It helps to reach a significant increase in etching selectivity. A method for destruction of an absorbed chromocontaining layer on the surface of polypropylene track membranes formed during etching has been elaborated. Experimental samples of the membranes for micro and ultrafiltration have been obtained and their properties have been studied in course of their exploitation in chemically aggressive agents. For t...

  3. A Stability Study of Alkali Doped PBI Membranes for Alkaline Electrolyzer Cells

    DEFF Research Database (Denmark)

    Jensen, Jens Oluf; Aili, David; Hansen, Martin Kalmar

    2014-01-01

    conductivity was similar to a commercial Zirfon membrane and suitable for a water electrolyzer. Some chemical degradation was seen during the aging period, but the crosslinked and the cured materials were both integral after 176 days of aging. A simplified electrolyzer test cell was operated successfully....

  4. Reflow process stabilization by chemical characteristics and process conditions

    Science.gov (United States)

    Kim, Myoung-Soo; Park, Jeong-Hyun; Kim, Hak-Joon; Kim, Il-Hyung; Jeon, Jae-Ha; Gil, Myung-Goon; Kim, Bong-Ho

    2002-07-01

    With the shrunken device rule below 130nm, the patterning of smaller contact hole with enough process margin is required for mass production. Therefore, shrinking technology using thermal reflow process has been applied for smaller contact hole formation. In this paper, we have investigated the effects of chemical characteristics such as molecular weight, blocking ratio of resin, cross-linker amount and solvent type with its composition to reflow process of resist and found the optimized chemical composition for reflow process applicable condition. And several process conditions like resist coating thickness and multi-step thermal reflow method have been also evaluated to stabilize the pattern profile and improve CD uniformity after reflow process. From the experiment results, it was confirmed that the effect of crosslinker in resist to reflow properties such as reflow temperature and reflow rate were very critical and it controlled the pattern profile during reflow processing. And also, it showed stable CD uniformity and improved resist properties for top loss, film shrinkage and etch selectivity. The application of lower coating thickness of resist induced symmetric pattern profile even at edge with wider process margin. The introduction of two-step baking method for reflow process showed uniform CD value, also. It is believed that the application of resist containing crosslinker and optimized process conditions for smaller contact hole patterning is necessary for the mass production with a design rule below 130nm.

  5. Color stability and staining of silorane after prolonged chemical challenges

    DEFF Research Database (Denmark)

    de Jesus, Vivian CBR; Martinelli, Nata Luiz; Poli-Frederico, Regina Célia

    Objectives: The purpose of this study was to investigate the effect of prolonged chemical challenges on color stability and staining susceptibility of a silorane-based composite material when compared to methacrylate-based composites. Methods: Cylindrical specimens (n=24) were fabricated from...... methacrylate (Filtek Z250, 3M ESPE; Filtek Z350XT, 3M ESPE; Master Fill, Biodinâmica) or silorane-based (Filtek P90, 3M ESPE) composite materials. Initial color was registered in a spectrophotometer. Specimens were divided in four groups and individually stored at 37°C in 0.02N citric acid, 0.02N phosphoric...... acid, 75% ethanol or distilled water (control) for 7, 14, 21, and 180 days, when new measurements were performed. A staining test was performed (n=12) after 21 days of chemical challenge by immersion in coffee during 3 weeks at 37°C. Color changes (¿E) were characterized using the CIEL*a*b* color...

  6. Sedative, membrane stability, cytotoxic and antioxidant properties of methanol extract of leaves of Protium serratum Wall.

    Directory of Open Access Journals (Sweden)

    Md. Rafikul Islam

    2014-09-01

    Full Text Available Objective: To study the sedative, membrane stability, cytotoxic and antioxidant properties of the leaves of Protium serratum extracted using methanol. Methods: Sedative test was performed using hole cross and open field methods at 200 and 400 mg/kg. Membrane stability of red blood cell was used for anti-inflammatory test at different concentrations. Cytotoxic study was performed using brine shrimp lethality test. Total flavonoid contents, total phenol contents and reducing power were used to assess antioxidant properties of the extract. Results: Extract showed better sedative action at lower doses in both experiments. Maximum 73.33% locomotion reduction was found at 200 mg/kg at 1 20 min and that was 89.29% for diazepam in hole cross test. In membrane stability test, extract and standard drug diclofenac have 35.66% and 91.20% stability, respectively. LC50 value of the extract was 22.91 µg/mL. Total phenol and flavonoid contents were (55.53依14.63 mg gallic acid equivalent per gram of extract and (1 06.33依7.35 mg of quercetin equivalent per gram of extract, respectively per gram of extract. Significant reducing power was observed as compared to ascorbic acid. Conclusions: Extract possesses good pharmacological properties. Hence, further extensive study is essential to find out possible active constituents for the treatment of anxiety, inflammation or sickle cell disease, cancer and free radical mediated abnormalities.

  7. Enhancing the Chemical and Mechanical Durability of Polymer Electrolyte Membranes for Fuel Cell Applications

    Science.gov (United States)

    Baker, Andrew M.

    Polymer electrolyte membrane (PEM) fuel cells are energy conversion devices which generate electricity from the electrochemical reaction of hydrogen and oxygen. Currently, widespread adoption of PEM fuel cell technology is hindered by low component durability and high costs. In this work, strategies were investigated to improve the mechanical and chemical durability of the ion conducting polymer, or ionomer, which comprises the PEM, in order to directly address these limitations. Owing to their exceptional mechanical properties, carbon nanotubes (CNTs) were investigated for mechanical reinforcement of the PEM. Because of their electronic conductivity, which diminishes cell performance, two strategies were developed to enable the use of CNTs as PEM reinforcement. These systems result in enhanced mechanical properties without sacrificing performance of the PEM during operation. Further, when coated with ceria (CeO2), which scavenges radicals that are generated during operation and cause PEM chemical degradation by attacking vulnerable chemical groups in the ionomer, MWCNTs further improved PEM chemical durability. During cell fabrication, conditioning, and discharge, Ce rapidly migrates between the PEM and catalyst layers (CLs), which reduces catalyst efficiency and leaves areas of the cell defenseless against radical attacks. Therefore, in order to stabilize Ce and localize it to areas of highest radical generation, it is critical to understand and identify the relative influences of different migration mechanisms. Using a novel elemental analysis technique, Ce migration was characterized due to potential and concentration gradients, water flux, and degradation of Ce-exchanged sulfonic acid groups within the PEM. Additionally, Zr-doped ceria was employed to resist migration due to ionomer degradation which improved cell durability, without reducing performance, resulting in PEM Ce stabilization near its initial concentrations after > 1,400 hours of testing. Ce was

  8. Functionalized polymer nanofibre membranes for protection from chemical warfare stimulants

    International Nuclear Information System (INIS)

    Ramaseshan, Ramakrishnan; Sundarrajan, Subramanian; Liu, Yingjun; Barhate, R S; Lala, Neeta L; Ramakrishna, S

    2006-01-01

    A catalyst for the detoxification of nerve agents is synthesized from β-cyclodextrin (β-CD) and o-iodosobenzoic acid (IBA). Functionalized polymer nanofibre membranes from PVC polymer are fabricated with β-CD, IBA, a blend of β-CD+IBA, and the synthesized catalyst. These functionalized nanofibres are then tested for the decontamination of paraoxon, a nerve agent stimulant, and it is observed that the stimulant gets hydrolysed. The kinetics of hydrolysis is investigated using UV spectroscopy. The rates of hydrolysis for different organophosphate hydrolyzing agents are compared. The reactivity and amount of adsorption of these catalysts are of higher capacity than the conventionally used activated charcoal. A new design for protective wear is proposed based on the functionalized nanofibre membrane

  9. Functionalized polymer nanofibre membranes for protection from chemical warfare stimulants

    Science.gov (United States)

    Ramaseshan, Ramakrishnan; Sundarrajan, Subramanian; Liu, Yingjun; Barhate, R. S.; Lala, Neeta L.; Ramakrishna, S.

    2006-06-01

    A catalyst for the detoxification of nerve agents is synthesized from β-cyclodextrin (β-CD) and o-iodosobenzoic acid (IBA). Functionalized polymer nanofibre membranes from PVC polymer are fabricated with β-CD, IBA, a blend of β-CD+IBA, and the synthesized catalyst. These functionalized nanofibres are then tested for the decontamination of paraoxon, a nerve agent stimulant, and it is observed that the stimulant gets hydrolysed. The kinetics of hydrolysis is investigated using UV spectroscopy. The rates of hydrolysis for different organophosphate hydrolyzing agents are compared. The reactivity and amount of adsorption of these catalysts are of higher capacity than the conventionally used activated charcoal. A new design for protective wear is proposed based on the functionalized nanofibre membrane.

  10. Functionalized polymer nanofibre membranes for protection from chemical warfare stimulants

    Energy Technology Data Exchange (ETDEWEB)

    Ramaseshan, Ramakrishnan [Nanoscience and Nanotechnology Initiative, National University of Singapore, 2 Engineering Drive 3, Singapore 117576, Singapore (Singapore); Sundarrajan, Subramanian [Nanoscience and Nanotechnology Initiative, National University of Singapore, 2 Engineering Drive 3, Singapore 117576, Singapore (Singapore); Liu, Yingjun [Department of Mechanical Engineering, National University of Singapore, 9 Engineering Drive 1, Singapore 117576, Singapore (Singapore); Barhate, R S [Nanoscience and Nanotechnology Initiative, National University of Singapore, 2 Engineering Drive 3, Singapore 117576, Singapore (Singapore); Lala, Neeta L [Nanoscience and Nanotechnology Initiative, National University of Singapore, 2 Engineering Drive 3, Singapore 117576, Singapore (Singapore); Ramakrishna, S [Nanoscience and Nanotechnology Initiative, National University of Singapore, 2 Engineering Drive 3, Singapore 117576, Singapore (Singapore)

    2006-06-28

    A catalyst for the detoxification of nerve agents is synthesized from {beta}-cyclodextrin ({beta}-CD) and o-iodosobenzoic acid (IBA). Functionalized polymer nanofibre membranes from PVC polymer are fabricated with {beta}-CD, IBA, a blend of {beta}-CD+IBA, and the synthesized catalyst. These functionalized nanofibres are then tested for the decontamination of paraoxon, a nerve agent stimulant, and it is observed that the stimulant gets hydrolysed. The kinetics of hydrolysis is investigated using UV spectroscopy. The rates of hydrolysis for different organophosphate hydrolyzing agents are compared. The reactivity and amount of adsorption of these catalysts are of higher capacity than the conventionally used activated charcoal. A new design for protective wear is proposed based on the functionalized nanofibre membrane.

  11. Pyrochlore as nuclear waste form. Actinide uptake and chemical stability

    Energy Technology Data Exchange (ETDEWEB)

    Finkeldei, Sarah Charlotte

    2015-07-01

    Radioactive waste is generated by many different technical and scientific applications. For the past decades, different waste disposal strategies have been considered. Several questions on the waste disposal strategy remain unanswered, particularly regarding the long-term radiotoxicity of minor actinides (Am, Cm, Np), plutonium and uranium. These radionuclides mainly arise from high level nuclear waste (HLW), specific waste streams or dismantled nuclear weapons. Although many countries have opted for the direct disposal of spent fuel, from a scientific and technical point of view it is imperative to pursue alternative waste management strategies. Apart from the vitrification, especially for trivalent actinides and Pu, crystalline ceramic waste forms are considered. In contrast to glasses, crystalline waste forms, which are chemically and physically highly stable, allow the retention of radionuclides on well-defined lattice positions within the crystal structure. Besides polyphase ceramics such as SYNROC, single phase ceramics are considered as tailor made host phases to embed a specific radionuclide or a specific group. Among oxidic single phase ceramics pyrochlores are known to have a high potential for this application. This work examines ZrO{sub 2} based pyrochlores as potential nuclear waste forms, which are known to show a high aqueous stability and a high tolerance towards radiation damage. This work contributes to (1) understand the phase stability field of pyrochlore and consequences of non-stoichiometry which leads to pyrochlores with mixed cationic sites. Mixed cationic occupancies are likely to occur in actinide-bearing pyrochlores. (2) The structural uptake of radionuclides themselves was studied. (3) The chemical stability and the effect of phase transition from pyrochlore to defect fluorite were probed. This phase transition is important, as it is the result of radiation damage in ZrO{sub 2} based pyrochlores. ZrO{sub 2} - Nd{sub 2}O{sub 3} pellets

  12. Pyrochlore as nuclear waste form. Actinide uptake and chemical stability

    International Nuclear Information System (INIS)

    Finkeldei, Sarah Charlotte

    2015-01-01

    Radioactive waste is generated by many different technical and scientific applications. For the past decades, different waste disposal strategies have been considered. Several questions on the waste disposal strategy remain unanswered, particularly regarding the long-term radiotoxicity of minor actinides (Am, Cm, Np), plutonium and uranium. These radionuclides mainly arise from high level nuclear waste (HLW), specific waste streams or dismantled nuclear weapons. Although many countries have opted for the direct disposal of spent fuel, from a scientific and technical point of view it is imperative to pursue alternative waste management strategies. Apart from the vitrification, especially for trivalent actinides and Pu, crystalline ceramic waste forms are considered. In contrast to glasses, crystalline waste forms, which are chemically and physically highly stable, allow the retention of radionuclides on well-defined lattice positions within the crystal structure. Besides polyphase ceramics such as SYNROC, single phase ceramics are considered as tailor made host phases to embed a specific radionuclide or a specific group. Among oxidic single phase ceramics pyrochlores are known to have a high potential for this application. This work examines ZrO 2 based pyrochlores as potential nuclear waste forms, which are known to show a high aqueous stability and a high tolerance towards radiation damage. This work contributes to (1) understand the phase stability field of pyrochlore and consequences of non-stoichiometry which leads to pyrochlores with mixed cationic sites. Mixed cationic occupancies are likely to occur in actinide-bearing pyrochlores. (2) The structural uptake of radionuclides themselves was studied. (3) The chemical stability and the effect of phase transition from pyrochlore to defect fluorite were probed. This phase transition is important, as it is the result of radiation damage in ZrO 2 based pyrochlores. ZrO 2 - Nd 2 O 3 pellets with pyrochlore and defect

  13. Maltose-neopentyl glycol (MNG) amphiphiles for solubilization, stabilization and crystallization of membrane proteins.

    Science.gov (United States)

    Chae, Pil Seok; Rasmussen, Søren G F; Rana, Rohini R; Gotfryd, Kamil; Chandra, Richa; Goren, Michael A; Kruse, Andrew C; Nurva, Shailika; Loland, Claus J; Pierre, Yves; Drew, David; Popot, Jean-Luc; Picot, Daniel; Fox, Brian G; Guan, Lan; Gether, Ulrik; Byrne, Bernadette; Kobilka, Brian; Gellman, Samuel H

    2010-12-01

    The understanding of integral membrane protein (IMP) structure and function is hampered by the difficulty of handling these proteins. Aqueous solubilization, necessary for many types of biophysical analysis, generally requires a detergent to shield the large lipophilic surfaces of native IMPs. Many proteins remain difficult to study owing to a lack of suitable detergents. We introduce a class of amphiphiles, each built around a central quaternary carbon atom derived from neopentyl glycol, with hydrophilic groups derived from maltose. Representatives of this maltose-neopentyl glycol (MNG) amphiphile family show favorable behavior relative to conventional detergents, as manifested in multiple membrane protein systems, leading to enhanced structural stability and successful crystallization. MNG amphiphiles are promising tools for membrane protein science because of the ease with which they may be prepared and the facility with which their structures may be varied.

  14. Improved glucose-neopentyl glycol (GNG) amphiphiles for membrane protein solubilization and stabilization.

    Science.gov (United States)

    Cho, Kyung Ho; Bae, Hyoung Eun; Das, Manabendra; Gellman, Samuel H; Chae, Pil Seok

    2014-02-01

    Membrane proteins are inherently amphipathic and undergo dynamic conformational changes for proper function within native membranes. Maintaining the functional structures of these biomacromolecules in aqueous media is necessary for structural studies but difficult to achieve with currently available tools, thus necessitating the development of novel agents with favorable properties. This study introduces several new glucose-neopentyl glycol (GNG) amphiphiles and reveals some agents that display favorable behaviors for the solubilization and stabilization of a large, multi-subunit membrane protein assembly. Furthermore, a detergent structure-property relationship that could serve as a useful guideline for the design of novel amphiphiles is discussed. Copyright © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  15. Understanding chemical-potential-related transient pore-pressure response to improve real-time borehole (in)stability predictions

    Energy Technology Data Exchange (ETDEWEB)

    Tare, U. A.; Mody, F. K.; Mese, A. I. [Haliburton Energy Services, TX (United States)

    2002-07-01

    In order to develop a real-time wellbore (in)stability modelling capability, experimental work was carried out to investigate the role of the chemical potential of drilling fluids on transient pore pressure and time-dependent rock property alterations of shale formations. Time-dependent alterations in the pore pressure, acoustic and rock properties of formations subjected to compressive tri-axial test were recorded during the experiments involving the Pore Pressure Transmission (PPT) test. Based on the transient pore pressure of shale exposed to the test fluid presented here, the 20 per cent calcium chloride showed a very low membrane efficiency of 4.45 per cent. The need for a thorough understanding of the drilling fluid/shale interaction prior to applying any chemical potential wellbore (in)stability model to real-time drilling operations was emphasized. 9 refs., 5 figs.

  16. Quinacrine pretreatment reduces microwave-induced neuronal damage by stabilizing the cell membrane

    Science.gov (United States)

    Ding, Xue-feng; Wu, Yan; Qu, Wen-rui; Fan, Ming; Zhao, Yong-qi

    2018-01-01

    Quinacrine, widely used to treat parasitic diseases, binds to cell membranes. We previously found that quinacrine pretreatment reduced microwave radiation damage in rat hippocampal neurons, but the molecular mechanism remains poorly understood. Considering the thermal effects of microwave radiation and the protective effects of quinacrine on heat damage in cells, we hypothesized that quinacrine would prevent microwave radiation damage to cells in a mechanism associated with cell membrane stability. To test this, we used retinoic acid to induce PC12 cells to differentiate into neuron-like cells. We then pretreated the neurons with quinacrine (20 and 40 mM) and irradiated them with 50 mW/cm2 microwaves for 3 or 6 hours. Flow cytometry, atomic force microscopy and western blot assays revealed that irradiated cells pretreated with quinacrine showed markedly less apoptosis, necrosis, and membrane damage, and greater expression of heat shock protein 70, than cells exposed to microwave irradiation alone. These results suggest that quinacrine stabilizes the neuronal membrane structure by upregulating the expression of heat shock protein 70, thus reducing neuronal injury caused by microwave radiation. PMID:29623929

  17. High-performance hybrid pervaporation membranes with superior hydrothermal and acid stability

    Energy Technology Data Exchange (ETDEWEB)

    Castricum, H.L. [Inorganic Materials Science, MESA Institute for Nanotechnology, University of Twente, P.O. Box 217, 7500 AE Enschede (Netherlands); Blank, D.H.A.; Ten Elshof, J.E. [Van ' t Hoff Institute for Molecular Sciences, University of Amsterdam, Nieuwe Achtergracht 166, 1018 WV Amsterdam (Netherlands); Kreiter, R.; Van Veen, H.M.; Vente, J.F. [ECN Efficiency and Infrastructure, Petten (Netherlands)

    2009-05-15

    A new organic-inorganic hybrid membrane has been prepared with exceptional performance in dewatering applications. The only precursor used in the sol-gel synthesis of the selective layer was organically linked 1,2-bis(triethoxysilyl)ethane (BTESE). The microporous structure of this layer enables selective molecular sieving of small molecules from larger ones. In the dehydration of n-butanol with 5% of water, the membrane shows a high separation factor of over 4000 and ultra-fast water transport at a rate of more than 20 kg m{sup -2} h{sup -1} at 150C. This can be related to the high adsorption capacity of the material and the sub-micron thickness of the selective layer. The selectivity has now remained constant over almost one and a half years under continuous process testing conditions. Apart from the hydrothermal stability, the membrane exhibits a high tolerance for acid contamination. A slow performance decline in flux and separation factor is only observed at a pH lower than 2. The high stability and effective separation indicate a broad industrial application potential of the hybrid membrane material.

  18. Chemical derivatization to enhance chemical/oxidative stability of resorcinol-formaldehyde resin

    Energy Technology Data Exchange (ETDEWEB)

    Hubler, T.L. [Pacific Northwest National Lab., Richland, WA (United States)

    1997-10-01

    The goal of this task is to develop modified resorcinol-formaldehyde (R-F) resin to improve the chemical/oxidative stability of the resin. R-F resin is a regenerable organic ion-exchange resin that is selective for cesium ion in highly alkaline, high ionic-strength solutions. R-F resin tends to undergo chemical degradation, reducing its ability to remove cesium ion from waste solutions; the mechanistic details of these decomposition reactions are currently unknown. The approach used for this task is chemical modification of the resin structure, particularly the resorcinol ring unit of the polymer resin. This approach is based on prior characterization studies conducted at Pacific Northwest National Laboratory (PNNL) that indicated the facile chemical degradation of the resin is oxidation of the resorcinol ring to the para-quinone structure, with subsequent loss of ion-exchange sites for cesium ion. R-F resin represents an important alternative to current radiocesium remediation technology for tank wastes at both the Hanford and Savannah River sites, particularly if regenerable resins are needed.

  19. Application of Photocured Polymer Ion Selective Membranes for Solid-State Chemical Sensors

    Directory of Open Access Journals (Sweden)

    Natalia Abramova

    2015-06-01

    Full Text Available Application of conducting polymers with additional functional groups for a solid contact formation and photocurable membranes as sensitive elements of solid-state chemical sensors is discussed. Problems associated with application of UV-curable polymers for sensors are analyzed. A method of sensor fabrication using copolymerized conductive layer and sensitive membrane is presented and the proof of concept is confirmed by two examples of solid-contact electrodes for Ca ions and pH.

  20. Chemical stability and physical properties of Caesium uranates

    International Nuclear Information System (INIS)

    Berton, J.P.; Baron, D.; Coquerelle, M.

    1998-01-01

    Caesium is one of the most abundant fission products in PWR nuclear fuel or in fast reactor fuel as well. A work program has been started at the TUI Karlsruhe, in collaboration with EDF Etudes et Recherches, to determine the thermal stability and conductivity, the mechanical properties and the thermal expansion coefficient of Cs 2 UO 4 . The Caesium mono-uranate was obtained by a chemical reaction between Cs 2 O 3 and U 3 O 8 powders mixed together, pressed and heated at 670 deg. C for 24 hours. The compound was found stable up to 830 deg. C. Mechanical compressive hardening tests allowed to evaluate the elastic modulus versus temperature in the range 200 to 800 deg. C. Furthermore the viscous behaviour of the compound above 400 deg. C was confirmed. The thermal expansion coefficient of Cs 2 UO 4 was found somewhat 40% higher than the thermal expansion coefficient of UO 2 . The thermal conductivity is about 1.5 to 1.8 W/m/K for temperatures ranging from 100 to 700 deg. C, a value very similar to the UO 2 fuel thermal conductivity at high burnup in the same temperature range. (author)

  1. Chemical vapor deposition of yttria stabilized zirconia in porous substrates

    International Nuclear Information System (INIS)

    Carolan, M.F.; Michaels, J.N.

    1987-01-01

    Electrochemical vapor deposition (EVD) of yttria stabilized zirconia (YSZ) is the preferred route to the production of thin films of YSZ on porous substrates. This process has been used in the construction of both fuel cells and steam electrolyzers. A critical aspect of the EVD process is an initial chemical vapor deposition phase in which the pores of a porous substrate are plugged by YSZ. In this process, water vapor and a mixture of gaseous zirconium chloride and yttrium chloride diffuse into the porous substrate from opposite sides and react to form YSZ and HCl ga. During the second stage of the process a continuous dense film of electrolyte is formed by a tarnishing-type process. Experimentally it is observed that the pores plug within a few pore diameters of the metal chloride face of the substrate. A kinetic rate expression that is first order in metal chloride but zero order in water is best able to explain this phenomenon. With this rate expression, the pores always plug near the metal chloride face. The model predicts less pore narrowing to occur as the ratio of the reaction rate to the diffusion rate of the metal chloride is increased. A kinetic rate expression that is first order in both water and metal chloride predicts that the pores plug much deeper in the substrate

  2. Method of waste stabilization with dewatered chemically bonded phosphate ceramics

    Science.gov (United States)

    Wagh, Arun; Maloney, Martin D.

    2010-06-29

    A method of stabilizing a waste in a chemically bonded phosphate ceramic (CBPC). The method consists of preparing a slurry including the waste, water, an oxide binder, and a phosphate binder. The slurry is then allowed to cure to a solid, hydrated CBPC matrix. Next, bound water within the solid, hydrated CBPC matrix is removed. Typically, the bound water is removed by applying heat to the cured CBPC matrix. Preferably, the quantity of heat applied to the cured CBPC matrix is sufficient to drive off water bound within the hydrated CBPC matrix, but not to volatalize other non-water components of the matrix, such as metals and radioactive components. Typically, a temperature range of between 100.degree. C.-200.degree. C. will be sufficient. In another embodiment of the invention wherein the waste and water have been mixed prior to the preparation of the slurry, a select amount of water may be evaporated from the waste and water mixture prior to preparation of the slurry. Another aspect of the invention is a direct anyhydrous CBPC fabrication method wherein water is removed from the slurry by heating and mixing the slurry while allowing the slurry to cure. Additional aspects of the invention are ceramic matrix waste forms prepared by the methods disclosed above.

  3. Study of structural stability and damaging effect on membrane for four Aβ42 dimers.

    Directory of Open Access Journals (Sweden)

    Wei Feng

    Full Text Available Increasing evidence shows that Aβ oligomers are key pathogenic molecules in Alzheimer's disease. Among Aβ oligomers, dimer is the smallest aggregate and toxic unit. Therefore, understanding its structural and dynamic properties is quite useful to prevent the formation and toxicity of the Aβ oligomers. In this study, we performed molecular dynamic simulations on four Aβ42 dimers, 2NCb, CNNC, NCNC and NCCN, within the hydrated DPPC membrane. Four Aβ42 dimers differ in the arrangements of two Aβ42 peptides. This study aims to investigate the impact of aggregation pattern of two Aβ peptides on the structural stability of the Aβ42 dimer and its disruption to the biological membrane. The MD results demonstrate that the NCCN, CNNC and NCNC have the larger structural fluctuation at the N-terminus of Aβ42 peptide, where the β-strand structure converts into the coil structure. The loss of the N-terminal β-strand further impairs the aggregate ability of Aβ42 dimer. In addition, inserting Aβ42 dimer into the membrane can considerably decrease the average APL of DPPC membrane. Moreover this decrease effect is largely dependent on the distance to the location of Aβ42 dimer and its secondary structure forms. Based on the results, the 2NCb is considered as a stable dimeric unit for aggregating the larger Aβ42 oligomer, and has a potent ability to disrupt the membrane.

  4. Integration of sand and membrane filtration systems for iron and pesticide removal without chemical addition

    DEFF Research Database (Denmark)

    Kowalski, Krysztof; Madsen, Henrik Tækker; Søgaard, Erik Gydesen

    2013-01-01

    the content of key foulants, the techniques can be used as a pre-treatment for nanofiltration and low pressure reverse osmosis that has proved to be capable of removing pesticides. It was found that a lower fouling potential could be obtained by using the membranes, but that sand filter was better at removing......Pilot plant investigations of sand and membrane filtration (MF/UF/NF/LPRO) have been performed to treat groundwater polluted with pesticides. The results show that simple treatment, with use of aeration and sand filtration or MF/UF membranes, does not remove pesticides. However, by reducing...... manganese and dissolved organic matter. The results indicate that combining aeration; sand filtration and membrane techniques might be a good option for pesticide removal without any addition of chemicals and minimized membrane maintenance....

  5. Chemical Vapor Deposition of Photocatalyst Nanoparticles on PVDF Membranes for Advanced Oxidation Processes

    Directory of Open Access Journals (Sweden)

    Giovanni De Filpo

    2018-06-01

    Full Text Available The chemical binding of photocatalytic materials, such as TiO2 and ZnO nanoparticles, onto porous polymer membranes requires a series of chemical reactions and long purification processes, which often result in small amounts of trapped nanoparticles with reduced photocatalytic activity. In this work, a chemical vapor deposition technique was investigated in order to allow the nucleation and growth of ZnO and TiO2 nanoparticles onto polyvinylidene difluoride (PVDF porous membranes for application in advanced oxidation processes. The thickness of obtained surface coatings by sputtered nanoparticles was found to depend on process conditions. The photocatalytic efficiency of sputtered membranes was tested against both a model drug and a model organic pollutant in a small continuous flow reactor.

  6. Chemical and microstructural analyses for heavy metals removal from water media by ceramic membrane filtration.

    Science.gov (United States)

    Ali, Asmaa; Ahmed, Abdelkader; Gad, Ali

    2017-01-01

    This study aims to investigate the ability of low cost ceramic membrane filtration in removing three common heavy metals namely; Pb 2+ , Cu 2+ , and Cd 2+ from water media. The work includes manufacturing ceramic membranes with dimensions of 15 by 15 cm and 2 cm thickness. The membranes were made from low cost materials of local clay mixed with different sawdust percentages of 0.5%, 2.0%, and 5.0%. The used clay was characterized by X-ray diffraction (XRD) and X-ray fluorescence analysis. Aqueous solutions of heavy metals were prepared in the laboratory and filtered through the ceramic membranes. The influence of the main parameters such as pH, initial driving pressure head, and concentration of heavy metals on their removal efficiency by ceramic membranes was investigated. Water samples were collected before and after the filtration process and their heavy metal concentrations were determined by chemical analysis. Moreover, a microstructural analysis using scanning electronic microscope (SEM) was performed on ceramic membranes before and after the filtration process. The chemical analysis results showed high removal efficiency up to 99% for the concerned heavy metals. SEM images approved these results by showing adsorbed metal ions on sides of the internal pores of the ceramic membranes.

  7. New generation of membrane efficient water-based drilling fluids: pragmatic and cost-effective solutions to borehole stability problems

    Energy Technology Data Exchange (ETDEWEB)

    Tare, U.A. [Haliburton, Calgary, AB (Canada); Mody, F.K. [Shell International E and P Inc., Calgary, AB (Canada); Tan, C.P. [CSIRO Petroleum, Kensington, WA (Australia)

    2002-06-01

    Drilling and completion operations in shales often suffer as a result of wellbore instability. Mechanical failure of the rock around a wellbore is the primary cause of shale instability. This process can be exacerbated by physico-chemical interactions between drilling fluids and shales. Water-based drilling fluids are used more and more due to environmental awareness that becomes more prevalent. Wellbore instability problems can however result from an improper application of water-based drilling fluids in those cases where drilling occurs in sensitive clay-rich formations. To meet the requirements of the petroleum industry, considerable collaborative efforts were expanded in the development of innovative environmentally acceptable water-based drilling fluids. In this paper, the authors describe the process that leads to the development of these drilling fluids. It is possible to achieve shale stability through an osmotic outflow of pore fluid and prevention/minimization of mud pressure penetration, as laboratory experiments on shale samples under realistic downhole conditions exposed to these drilling fluids prove. High membrane efficiencies, in excess of 80 per cent, were generated by this new generation of membrane efficient water-based drilling fluids. Drilling objectives resulting from an improved application of water-based drilling fluids are made possible by a fundamental understanding of the main drilling fluid-shale interaction mechanisms for shale stability and the application of experimental data to field conditions. The authors indicate that the achievement of trouble-free drilling of shales and notable reductions in non-productive time is accomplished by following the practical guidelines included in this paper for maintaining shale stability with the new generation of water-based drilling fluids. 8 refs., 2 tabs., 4 figs.

  8. Chemical synthesis of membrane proteins by the removable backbone modification method.

    Science.gov (United States)

    Tang, Shan; Zuo, Chao; Huang, Dong-Liang; Cai, Xiao-Ying; Zhang, Long-Hua; Tian, Chang-Lin; Zheng, Ji-Shen; Liu, Lei

    2017-12-01

    Chemical synthesis can produce membrane proteins bearing specifically designed modifications (e.g., phosphorylation, isotope labeling) that are difficult to obtain through recombinant protein expression approaches. The resulting homogeneously modified synthetic membrane proteins are valuable tools for many advanced biochemical and biophysical studies. This protocol describes the chemical synthesis of membrane proteins by condensation of transmembrane peptide segments through native chemical ligation. To avoid common problems encountered due to the poor solubility of transmembrane peptides in almost any solvent, we describe an effective procedure for the chemical synthesis of membrane proteins through the removable-backbone modification (RBM) strategy. Two key steps of this protocol are: (i) installation of solubilizing Arg4-tagged RBM groups into the transmembrane peptides at any primary amino acid through Fmoc (9-fluorenylmethyloxycarbonyl) solid-phase peptide synthesis and (ii) native ligation of the full-length sequence, followed by removal of the RBM tags by TFA (trifluoroacetic acid) cocktails to afford the native protein. The installation of RBM groups is achieved by using 4-methoxy-5-nitrosalicyladehyde by reduction amination to incorporate an activated O-to-N acyl transfer auxiliary. The Arg4-tag-modified membrane-spanning peptide segments behave like water-soluble peptides to facilitate their purification, ligation and mass characterization.

  9. Developmentally regulated GTP-binding protein 2 is required for stabilization of Rac1-positive membrane tubules.

    Science.gov (United States)

    Mani, Muralidharan; Lee, Unn Hwa; Yoon, Nal Ae; Yoon, Eun Hye; Lee, Byung Ju; Cho, Wha Ja; Park, Jeong Woo

    2017-11-04

    Previously we have reported that developmentally regulated GTP-binding protein 2 (DRG2) localizes on Rab5 endosomes and plays an important role in transferrin (Tfn) recycling. We here identified DRG2 as a key regulator of membrane tubule stability. At 30 min after Tfn treatment, DRG2 localized to membrane tubules which were enriched with phosphatidylinositol 4-monophosphate [PI(4)P] and did not contain Rab5. DRG2 interacted with Rac1 more strongly with GTP-bound Rac1 and tubular localization of DRG2 depended on Rac1 activity. DRG2 depletion led to destabilization of membrane tubules, while ectopic expression of DRG2 rescued the stability of the membrane tubules in DRG2-depleted cells. Our results reveal a novel mechanism for regulation of membrane tubule stability mediated by DRG2. Copyright © 2017 Elsevier Inc. All rights reserved.

  10. Influence of the use of statin on the stability of erythrocyte membranes in multiple sclerosis.

    Science.gov (United States)

    de Freitas, Mariana Vaini; de Oliveira, Marcela Ramos; dos Santos, Diogo Fernandes; de Cássia Mascarenhas Netto, Rita; Fenelon, Sheila Bernardino; Penha-Silva, Nilson

    2010-02-01

    Multiple sclerosis (MS) probably occurs by oxidative, inflammatory and autoimmune mechanisms. This study investigated the influence of statin on the stability of erythrocyte membranes in MS patients. The population was composed of one group with simvastatin therapy (20 mg/day), another group without statin therapy and a healthy control group. The stability of erythrocytes was evaluated by the half-transition points, H(50) and D(50), obtained from the curves of hemolysis induced by hypotonic shock and ethanol action, respectively. Erythrocytes of MS patients were less stable against lysis by both chaotropes. This behavior may be merely a consequence of the lifestyle of MS patients or it may be intrinsically associated with the conjunct of factors responsible for the development of the disease. The use of statin by MS patients was associated with lower levels of LDL and total cholesterol, as expected, and with higher stability of erythrocytes against ethanol compared to the values of untreated MS patients.

  11. Chemical, computational and functional insights into the chemical stability of the Hedgehog pathway inhibitor GANT61.

    Science.gov (United States)

    Calcaterra, Andrea; Iovine, Valentina; Botta, Bruno; Quaglio, Deborah; D'Acquarica, Ilaria; Ciogli, Alessia; Iazzetti, Antonia; Alfonsi, Romina; Lospinoso Severini, Ludovica; Infante, Paola; Di Marcotullio, Lucia; Mori, Mattia; Ghirga, Francesca

    2018-12-01

    This work aims at elucidating the mechanism and kinetics of hydrolysis of GANT61, the first and most-widely used inhibitor of the Hedgehog (Hh) signalling pathway that targets Glioma-associated oncogene homologue (Gli) proteins, and at confirming the chemical nature of its bioactive form. GANT61 is poorly stable under physiological conditions and rapidly hydrolyses into an aldehyde species (GANT61-A), which is devoid of the biological activity against Hh signalling, and a diamine derivative (GANT61-D), which has shown inhibition of Gli-mediated transcription. Here, we combined chemical synthesis, NMR spectroscopy, analytical studies, molecular modelling and functional cell assays to characterise the GANT61 hydrolysis pathway. Our results show that GANT61-D is the bioactive form of GANT61 in NIH3T3 Shh-Light II cells and SuFu -/- mouse embryonic fibroblasts, and clarify the structural requirements for GANT61-D binding to Gli1. This study paves the way to the design of GANT61 derivatives with improved potency and chemical stability.

  12. Morphological, Chemical Surface, and Diffusive Transport Characterizations of a Nanoporous Alumina Membrane

    Directory of Open Access Journals (Sweden)

    María I. Vázquez

    2015-12-01

    Full Text Available Synthesis of a nanoporous alumina membrane (NPAM by the two-step anodization method and its morphological and chemical surface characterization by analyzing Scanning Electron Microscopy (SEM micrographs and X-Ray Photoelectron Spectroscopy (XPS spectra is reported. Influence of electrical and diffusive effects on the NaCl transport across the membrane nanopores is determined from salt diffusion measurements performed with a wide range of NaCl concentrations, which allows the estimation of characteristic electrochemical membrane parameters such as the NaCl diffusion coefficient and the concentration of fixed charges in the membrane, by using an appropriated model and the membrane geometrical parameters (porosity and pore length. These results indicate a reduction of ~70% in the value of the NaCl diffusion coefficient through the membrane pores with respect to solution. The transport number of ions in the membrane pores (Na+ and Cl−, respectively were determined from concentration potential measurements, and the effect of concentration-polarization at the membrane surfaces was also considered by comparing concentration potential values obtained with stirred solutions (550 rpm and without stirring. From both kinds of results, a value higher than 0.05 M NaCl for the feed solution seems to be necessary to neglect the contribution of electrical interactions in the diffusive transport.

  13. 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....

  14. Effect of acidic aqueous solution on chemical and physical properties of polyamide NF membranes

    Science.gov (United States)

    Jun, Byung-Moon; Kim, Su Hwan; Kwak, Sang Kyu; Kwon, Young-Nam

    2018-06-01

    This work was systematically investigated the effects of acidic aqueous solution (15 wt% sulfuric acid as model wastewater from smelting process) on the physical and chemical properties of commercially available nanofiltration (NF) polyamide membranes, using piperazine (PIP)-based NE40/70 membranes and m-phenylene diamine (MPD)-based NE90 membrane. Surface properties of the membranes were studied before and after exposure to strong acid using various analytical tools: Scanning Electron Microscopy (SEM), Attenuated Total Reflectance-Fourier Transform Infrared spectroscopy (ATR-FTIR), X-ray photoelectron spectroscopy (XPS), Time-of-Flight Secondary Ion Mass Spectrometry (ToF-SIMS), contact angle analyzer, and electrophoretic light scattering spectrophotometer. The characterization and permeation results showed piperazine-based NE40/70 membranes have relatively lower acid-resistance than MPD-based NE90 membrane. Furthermore, density functional theory (DFT) calculation was also conducted to reveal the different acid-tolerances between the piperazine-based and MPD-based polyamide membranes. The easiest protonation was found to be the protonation of oxygen in piperazine-based monomer, and the N-protonation of the monomer had the lowest energy barrier in the rate determining step (RDS). The calculations were well compatible with the surface characterization results. In addition, the energy barrier in RDS is highly correlated with the twist angle (τD), which determines the delocalization of electrons between the carbonyl πCO bond and nitrogen lone pair, and the tendency of the twist angle was also maintained in longer molecules (dimer and trimer). This study clearly explained why the semi-aromatic membrane (NE40/70) is chemically less stable than the aromatic membrane (NE90) given the surface characterizations and DFT calculation results.

  15. Lysosomal membrane stability of the mussel, Mytilus galloprovincialis (L.), as a biomarker of tributyltin exposure.

    Science.gov (United States)

    Okoro, Hussein K; Snyman, Reinette G; Fatoki, Olalekan S; Adekola, Folahan A; Ximba, Bhekumusa J; Slabber, Michelle Y

    2015-05-01

    The effect of tributyltin (TBT) on the stability of hemocytic lysosome membranes of the mussel, Mytilus galloprovincialis, and the use thereof as a biomarker of TBT-induced stress, was investigated. Mussels were exposed to 0.1 and 1.0 µg/L tributyltin respectively for 4 weeks. Lysosomal membrane stability of hemocytes was tested weekly by means of the neutral red retention time (NRRT) assay, after which the mussel samples were analyzed for TBT content. The two exposed groups exhibited significantly increased (p < 0.05) whole body TBT concentrations with concomitant significant decreases (p < 0.05) in NRRT (R(2) values of 0.85 and 0.971 for lower and higher exposure groups, respectively). The higher exposure group showed a typical dose-response curve. For the control, no TBT was detected and NRRT remained stable. It was concluded that the NRRT assay could be considered as a useful technique, and lysosomal membrane destabilization a useful early warning and cellular biomarker of stress due to TBT exposure in M. galloprovincialis.

  16. Conditions that Stabilize Membrane Domains Also Antagonize n-Alcohol Anesthesia

    Science.gov (United States)

    Machta, Benjamin B.; Gray, Ellyn; Nouri, Mariam; McCarthy, Nicola L. C.; Gray, Erin M.; Miller, Ann L.; Brooks, Nicholas J.; Veatch, Sarah L.

    2016-08-01

    Diverse molecules induce general anesthesia with potency strongly correlated both with their hydrophobicity and their effects on certain ion channels. We recently observed that several n-alcohol anesthetics inhibit heterogeneity in plasma membrane derived vesicles by lowering the critical temperature ($T_c$) for phase separation. Here we exploit conditions that stabilize membrane heterogeneity to further test the correlation between the anesthetic potency of n-alcohols and effects on $T_c$. First we show that hexadecanol acts oppositely to n-alcohol anesthetics on membrane mixing and antagonizes ethanol induced anesthesia in a tadpole behavioral assay. Second, we show that two previously described `intoxication reversers' raise $T_c$ and counter ethanol's effects in vesicles, mimicking the findings of previous electrophysiological and behavioral measurements. Third, we find that hydrostatic pressure, long known to reverse anesthesia, also raises $T_c$ in vesicles with a magnitude that counters the effect of butanol at relevant concentrations and pressures. Taken together, these results demonstrate that $\\Delta T_c$ predicts anesthetic potency for n-alcohols better than hydrophobicity in a range of contexts, supporting a mechanistic role for membrane heterogeneity in general anesthesia.

  17. Hydrolytic Degradation and Mechanical Stability of Poly(ε-Caprolactone)/Reduced Graphene Oxide Membranes as Scaffolds for In Vitro Neural Tissue Regeneration.

    Science.gov (United States)

    Sánchez-González, Sandra; Diban, Nazely; Urtiaga, Ane

    2018-03-05

    The present work studies the functional behavior of novel poly(ε-caprolactone) (PCL) membranes functionalized with reduced graphene oxide (rGO) nanoplatelets under simulated in vitro culture conditions (phosphate buffer solution (PBS) at 37 °C) during 1 year, in order to elucidate their applicability as scaffolds for in vitro neural regeneration. The morphological, chemical, and DSC results demonstrated that high internal porosity of the membranes facilitated water permeation and procured an accelerated hydrolytic degradation throughout the bulk pathway. Therefore, similar molecular weight reduction, from 80 kDa to 33 kDa for the control PCL, and to 27 kDa for PCL/rGO membranes, at the end of the study, was observed. After 1 year of hydrolytic degradation, though monomers coming from the hydrolytic cleavage of PCL diffused towards the PBS medium, the pH was barely affected, and the rGO nanoplatelets mainly remained in the membranes which envisaged low cytotoxic effect. On the other hand, the presence of rGO nanomaterials accelerated the loss of mechanical stability of the membranes. However, it is envisioned that the gradual degradation of the PCL/rGO membranes could facilitate cells infiltration, interconnectivity, and tissue formation.

  18. Monatomic chemical-vapor-deposited graphene membranes bridge a half-millimeter-scale gap.

    Science.gov (United States)

    Lee, Choong-Kwang; Hwangbo, Yun; Kim, Sang-Min; Lee, Seoung-Ki; Lee, Seung-Mo; Kim, Seong-Su; Kim, Kwang-Seop; Lee, Hak-Joo; Choi, Byung-Ik; Song, Chang-Kyu; Ahn, Jong-Hyun; Kim, Jae-Hyun

    2014-03-25

    One of the main concerns in nanotechnology is the utilization of nanomaterials in macroscopic applications without losing their extreme properties. In an effort to bridge the gap between the nano- and macroscales, we propose a clever fabrication method, the inverted floating method (IFM), for preparing freestanding chemical-vapor-deposited (CVD) graphene membranes. These freestanding membranes were then successfully suspended over a gap a half-millimeter in diameter. To understand the working principle of IFM, high-speed photography and white light interferometry were used to characterize and analyze the deformation behaviors of the freestanding graphene membranes in contact with a liquid during fabrication. Some nanoscale configurations in the macroscopic graphene membranes were able to be characterized by simple optical microscopy. The proposed IFM is a powerful approach to investigating the macroscopic structures of CVD graphene and enables the exploitation of freestanding CVD graphene for device applications.

  19. SCREENING FOR TOXIC INDUSTRIAL CHEMICALS USING SEMIPERMEABLE MEMBRANE DEVICES WITH RAPID TOXICITY ASSAYS

    Science.gov (United States)

    A time-integrated sampling device interfaced with two toxicity-based assays is reported for monitoring volatile toxic industrial chemicals (TICs). Semipermeable membrane devices (SPMDs) using dimethylsulfoxide (DMSO) as the fill solvent accumulated each of 17 TICs from the vapor...

  20. Chemical treatment of commercial reverse osmosis membranes for use in FO

    Science.gov (United States)

    Commercially available reverse osmosis (RO) membranes – SW30HR, BW30, and AG – were chemically treated for use in forward osmosis (FO). Nitric acid, phosphoric acid, sulfuric acid, ethanol, and ethanol–acid–water ternary solutions were employed for the treatment. All three membra...

  1. The effect of gas permeation through vertical membranes on chemical switching reforming (CSR) reactor performance

    NARCIS (Netherlands)

    Wassie, S.A.; Gallucci, F.; Cloete, S.; Zaabout, A.; van Sint Annaland, M.; Amini, S.

    2016-01-01

    A novel membrane assisted fluidized bed reactor concept has been proposed for ultra-pure hydrogen production with integrated CO2 capture from steam methane reforming. The so-called Chemical Switching Reactor (CSR) concept combines the use of an oxygen carrier for supplying heat and catalysing 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. Chemical cleaning/disinfection and ageing of organic UF membranes: a review.

    Science.gov (United States)

    Regula, C; Carretier, E; Wyart, Y; Gésan-Guiziou, G; Vincent, A; Boudot, D; Moulin, P

    2014-06-01

    Membrane separation processes have become a basic unit operation for process design and product development. These processes are used in a variety of separation and concentration steps, but in all cases, the membranes must be cleaned regularly to remove both organic and inorganic material deposited on the surface and/or into the membrane bulk. Cleaning/disinfection is a vital step in maintaining the permeability and selectivity of the membrane in order to get the plant to its original capacity, to minimize risks of bacteriological contamination, and to make acceptable products. For this purpose, a large number of chemical cleaning/disinfection agents are commercially available. In general, these cleaning/disinfection agents have to improve the membrane flux to a certain extent. However, they can also cause irreversible damages in membrane properties and performances over the long term. Until now, there is considerably less literature dedicated to membrane ageing than to cleaning/disinfection. The knowledge in cleaning/disinfection efficiency has recently been improved. But in order to develop optimized cleaning/disinfection protocols there still remains a challenge to better understand membrane ageing. In order to compensate for the lack of correlated cleaning/disinfection and ageing data from the literature, this paper investigates cleaning/disinfection efficiencies and ageing damages of organic ultrafiltration membranes. The final aim is to provide less detrimental cleaning/disinfection procedures and to propose some guidelines which should have been taken into consideration in term of membrane ageing studies. To carry out this study, this article will detail the background of cleaning/disinfection and aging membrane topics in a first introductive part. In a second part, key factors and endpoints of cleaning/disinfection and aging membranes will be discussed deeply: the membrane role and the cleaning parameters roles, such as water quality, storing conditions

  4. Method of producing a carbon coated ceramic membrane and associated product

    Science.gov (United States)

    Liu, Paul K. T.; Gallaher, George R.; Wu, Jeffrey C. S.

    1993-01-01

    A method of producing a carbon coated ceramic membrane including passing a selected hydrocarbon vapor through a ceramic membrane and controlling ceramic membrane exposure temperature and ceramic membrane exposure time. The method produces a carbon coated ceramic membrane of reduced pore size and modified surface properties having increased chemical, thermal and hydrothermal stability over an uncoated ceramic membrane.

  5. Microfluidic Device for Controllable Chemical Release via Field-Actuated Membrane Incorporating Nanoparticles

    Directory of Open Access Journals (Sweden)

    Xiang Wang

    2013-01-01

    Full Text Available We report a robust magnetic-membrane-based microfluidic platform for controllable chemical release. The magnetic membrane was prepared by mixing polydimethylsiloxane (PDMS and carbonyl-iron nanoparticles together to obtain a flexible thin film. With combined, simultaneous regulation of magnetic stimulus and mechanical pumping, the desired chemical release rate can easily be realized. For example, the dose release experimental data was well fitted by a mathematical sigmoidal model, exhibiting a typical dose-response relationship, which shows promise in providing significant guidance for on-demand drug delivery. To test the platform’s feasibility, our microfluidic device was employed in an experiment involving Escherichia coli culture under controlled antibiotic ciprofloxacin exposure, and the expected outcomes were successfully obtained. Our experimental results indicate that such a microfluidic device, with high accuracy and easy manipulation properties, can legitimately be characterized as active chemical release system.

  6. Microfluidic Device for Controllable Chemical Release via Field-Actuated Membrane Incorporating Nanoparticles

    KAUST Repository

    Wang, Xiang; Li, Shunbo; Wang, Limu; Yi, Xin; Hui, Yu Sanna; Qin, Jianhua; Wen, Weijia

    2013-01-01

    We report a robust magnetic-membrane-based microfluidic platform for controllable chemical release. The magnetic membrane was prepared by mixing polydimethylsiloxane (PDMS) and carbonyl-iron nanoparticles together to obtain a flexible thin film. With combined, simultaneous regulation of magnetic stimulus and mechanical pumping, the desired chemical release rate can easily be realized. For example, the dose release experimental data was well fitted by a mathematical sigmoidal model, exhibiting a typical dose-response relationship, which shows promise in providing significant guidance for on-demand drug delivery. To test the platform’s feasibility, our microfluidic device was employed in an experiment involving Escherichia coli culture under controlled antibiotic ciprofloxacin exposure, and the expected outcomes were successfully obtained. Our experimental results indicate that such a microfluidic device, with high accuracy and easy manipulation properties, can legitimately be characterized as active chemical release system.

  7. Microfluidic Device for Controllable Chemical Release via Field-Actuated Membrane Incorporating Nanoparticles

    KAUST Repository

    Wang, Xiang

    2013-01-01

    We report a robust magnetic-membrane-based microfluidic platform for controllable chemical release. The magnetic membrane was prepared by mixing polydimethylsiloxane (PDMS) and carbonyl-iron nanoparticles together to obtain a flexible thin film. With combined, simultaneous regulation of magnetic stimulus and mechanical pumping, the desired chemical release rate can easily be realized. For example, the dose release experimental data was well fitted by a mathematical sigmoidal model, exhibiting a typical dose-response relationship, which shows promise in providing significant guidance for on-demand drug delivery. To test the platform’s feasibility, our microfluidic device was employed in an experiment involving Escherichia coli culture under controlled antibiotic ciprofloxacin exposure, and the expected outcomes were successfully obtained. Our experimental results indicate that such a microfluidic device, with high accuracy and easy manipulation properties, can legitimately be characterized as active chemical release system.

  8. Triphenylamine - a 'new' stabilizer for nitrocellulose based propellants. Pt. 1: chemical stability studies

    Energy Technology Data Exchange (ETDEWEB)

    Wilker, Stephan; Heeb, Gerhard [WIWEB ASt Heimerzheim, Grosses Cent, 53913 Swisttal (Germany); Vogelsanger, Beat [Nitrochemie Wimmis AG, Niesenstr. 44, 3752 Wimmis (Switzerland); Petrzilek, Jan; Skladal, Jan [Explosia a.s. - Research Institute of Industrial Chemistry (VUPCH), 532 17 Pardubice (Czech Republic)

    2007-04-15

    Triphenylamine (TPA) was used for the first time in France in 1937 as a stabilizer for propellants. The stability of those samples was described as 'good'. Around 1950 an American group produced TPA stabilized propellants and investigated the decomposition mechanism. Apart from one single experiment in the 1970s no further attempts were made to take TPA as a stabilizer for propellants. With the background of an increasingly critical discussion about nitrosamines in propellants and their declaration of being carcinogenic, TPA revealed a renaissance since the year 2000. To achieve the goal of nitrosamine free propellants several TPA stabilized propellants were produced. Their processability, stability and ballistic properties were investigated. This publication summarizes the most important results of stability tests on more than 30 different TPA stabilized propellants including the decomposition mechanism, the synthesis of the consecutive products and their stabilizing properties. In addition, the internal compatibility of TPA with the most important propellant ingredients is discussed and its relative decomposition rate is compared with that of other stabilizers. In summary TPA is a suitable stabilizer for propellants. It has nevertheless two disadvantages. It is relatively rapidly consumed in double base formulations (which makes it difficult to pass the criteria of AOP-48, Ed. 2) and the stabilizing activity of the two major consecutive products 4-NO{sub 2}-TPA and especially 4,4{sup '}-di-NO{sub 2}-TPA is low. (Abstract Copyright [2007], Wiley Periodicals, Inc.)

  9. Physical and chemical stability of the bentonite buffer

    Energy Technology Data Exchange (ETDEWEB)

    Jinsong Liu; Neretnieks, Ivars [Chemical Engineering and Technology, Royal I nstitute of Technology, Stockholm (Sweden)

    2007-12-15

    A literature study was made on previous work on clay erosion and on the fundamental processes that govern the stability of clay gels. Mechanical erosion has been studied earlier and models devised to estimate the tendency to erode. We have used a different approach that we deem is fundamentally more correct. Chemical erosion processes have not been found to be studied previously and we have approached the problem by applying simple but fundamental mass balances and transport processes to the problem. The physical and chemical processes that govern the repulsive and cohesive forces in clay are well understood in principle but cannot yet be applied quantitatively to predict the gel/sol behaviour of the bentonite clay. It was necessary to rely directly on laboratory measurements for information on swelling and gel/sol properties. The backfill bentonite clay acts as a Bingham fluid over a wide range of clay density. To mobilise the clay a shear stress larger than the Bingham yield stress must be applied to the gel. The Bingham yield stress has been measured to be larger than 1 Pa (N/m{sup 2}) although it cannot be ruled out that lower values can be found under different experimental conditions than those reported. Shear stresses exerted by the water flowing in the fractures that intersect the deposition holes with the clay backfill have been estimated for a wide range of fracture transmissivities, apertures and hydraulic gradients that could exist under repository conditions. This includes the extremely high gradients that could exist during some periods during an ice age. For fracture transmissivities ranging from 10{sup -9} to 10{sup -6} m{sup 2}/s, fracture apertures from 0.1 to 2 mm and the hydraulic gradients from 0.01 to 1 mH{sub 2}O/m, the largest local shear stress found in this range was about 0.1 Pa. To investigate a 'what if' situation where the shear stress exceeds the yield stress simple models were devised. They were used to assess the rate of

  10. Physical and chemical stability of the bentonite buffer

    International Nuclear Information System (INIS)

    Jinsong Liu; Neretnieks, Ivars

    2007-12-01

    A literature study was made on previous work on clay erosion and on the fundamental processes that govern the stability of clay gels. Mechanical erosion has been studied earlier and models devised to estimate the tendency to erode. We have used a different approach that we deem is fundamentally more correct. Chemical erosion processes have not been found to be studied previously and we have approached the problem by applying simple but fundamental mass balances and transport processes to the problem. The physical and chemical processes that govern the repulsive and cohesive forces in clay are well understood in principle but cannot yet be applied quantitatively to predict the gel/sol behaviour of the bentonite clay. It was necessary to rely directly on laboratory measurements for information on swelling and gel/sol properties. The backfill bentonite clay acts as a Bingham fluid over a wide range of clay density. To mobilise the clay a shear stress larger than the Bingham yield stress must be applied to the gel. The Bingham yield stress has been measured to be larger than 1 Pa (N/m 2 ) although it cannot be ruled out that lower values can be found under different experimental conditions than those reported. Shear stresses exerted by the water flowing in the fractures that intersect the deposition holes with the clay backfill have been estimated for a wide range of fracture transmissivities, apertures and hydraulic gradients that could exist under repository conditions. This includes the extremely high gradients that could exist during some periods during an ice age. For fracture transmissivities ranging from 10 -9 to 10 -6 m 2 /s, fracture apertures from 0.1 to 2 mm and the hydraulic gradients from 0.01 to 1 mH 2 O/m, the largest local shear stress found in this range was about 0.1 Pa. To investigate a 'what if' situation where the shear stress exceeds the yield stress simple models were devised. They were used to assess the rate of erosion by the groundwater. In

  11. Ozone mass transfer behaviors on physical and chemical absorption for hollow fiber membrane contactors.

    Science.gov (United States)

    Zhang, Yong; Li, Kuiling; Wang, Jun; Hou, Deyin; Liu, Huijuan

    2017-09-01

    To understand the mass transfer behaviors in hollow fiber membrane contactors, ozone fluxes affected by various conditions and membranes were investigated. For physical absorption, mass transfer rate increased with liquid velocity and the ozone concentration in the gas. Gas flow rate was little affected when the velocity was larger than the critical value, which was 6.1 × 10 -3 m/s in this study. For chemical absorption, the flux was determined by the reaction rate between ozone and the absorbent. Therefore, concentration, species, and pH affected the mass transfer process markedly. For different absorbents, the order of mass transfer rate was the same as the reaction rate constant, which was phenol, sodium nitrite, hydrogen peroxide, and oxalate. Five hydrophobic membranes with various properties were employed and the mass transfer behavior can be described by the Graetz-Lévèque equation for the physical absorption process. The results showed the process was controlled by liquid film and the gas phase conditions, and membrane properties did not affect the ozone flux. For the chemical absorption, gas film, membrane and liquid film affected the mass transfer together, and none of them were negligible.

  12. Stabilization of low-level mixed waste in chemically bonded phosphate ceramics

    International Nuclear Information System (INIS)

    Wagh, A.S.; Singh, D.; Sarkar, A.V.

    1994-06-01

    Mixed waste streams, which contain both chemical and radioactive wastes, are one of the important categories of DOE waste streams needing stabilization for final disposal. Recent studies have shown that chemically bonded phosphate ceramics may have the potential for stabilizing these waste streams, particularly those containing volatiles and pyrophorics. Such waste streams cannot be stabilized by conventional thermal treatment methods such as vitrification. Phosphate ceramics may be fabricated at room temperature into durable, hard and dense materials. For this reason room-temperature-setting phosphate ceramic waste forms are being developed to stabilize these to ''problem waste streams.''

  13. Synthesis of mesh-shaped calcia partially stabilized zirconia using eggshell membrane template as filler composite

    Directory of Open Access Journals (Sweden)

    Gema Gempita

    2017-08-01

    Full Text Available This experiment was conducted experimentally to synthesize Calcia Partially Stabilized Zirconia (Ca-PSZ by sol-gel method using eggshell membrane template as a composite filler. The eggshell membrane was used to produce a mesh shaped structure, which hopefully can improve the mechanical properties of the composite. Ca-PSZ filler was synthesized from ZrOCl2 precursor and Ca(NO32 stabilizer with a 24 hours immersion time. Ca-PSZ of synthesis then mixed with the resin matrix to test its composite hardness. The EDS characterization results suggested that the sample contained elements of zirconia, calcium, and oxygen. Whereas, the XRD characterization identified that crystal structures that formed in the sample were nano scale tetragonal. Characterization of SEM showed Ca-PSZ with mesh structured. The average composite hardness value was 15.79 VHN. The composites with Ca-PSZ-synthesized filler could be prepared and its hardness value was higher than the composite with Ca-PSZ filler in spherical particles, but the hardness was still below the composite on the market.

  14. Chemically Stable Covalent Organic Framework (COF)-Polybenzimidazole Hybrid Membranes: Enhanced Gas Separation through Pore Modulation.

    Science.gov (United States)

    Biswal, Bishnu P; Chaudhari, Harshal D; Banerjee, Rahul; Kharul, Ulhas K

    2016-03-24

    Highly flexible, TpPa-1@PBI-BuI and TpBD@PBI-BuI hybrid membranes based on chemically stable covalent organic frameworks (COFs) could be obtained with the polymer. The loading obtained was substantially higher (50 %) than generally observed with MOFs. These hybrid membranes show an exciting enhancement in permeability (about sevenfold) with appreciable separation factors for CO2/N2 and CO2/CH4. Further, we found that with COF pore modulation, the gas permeability can be systematically enhanced. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  15. Enhanced Performance of Thin Film Composite Forward Osmosis Membrane by Chemical Post-Treatment

    Science.gov (United States)

    Liu, Zheng; Chen, Jiangrong; Cao, Zhen; Wang, Jian; Guo, Chungang

    2018-01-01

    Forward osmosis is an attractive technique in water purification and desalination fields. Enhancement of the forward osmosis membrane performance is essential to the application of this technique. In this study, an optimized chemical post-treatment approach which was used to improve RO membrane performance was employed for enhancing water flux of thin film composite forward osmosis membrane. Home-made polysulfide-based forward osmosis membrane was prepared and nitric acid, sulfuric acid, ethanol, 2-propanol were employed as post-treatment solutions. After a short-term treatment, all the membrane samples manifested water flux enhancement compared with their untreated counterparts. Over 50% increase of water flux had been obtained by ethanol solution treatment. The swelling, changes of hydrophobicity and solvency in both active layer and substrate were verified as the major causes for the enhancement of the water flux. It is noted that the treatment time and solution concentration should be controlled to get both appropriate water flux and reverse salt flux. The results obtained in this study will be useful for further FO membrane development and application.

  16. Enhanced forward osmosis from chemically modified polybenzimidazole (PBI) nanofiltration hollow fiber membranes with a thin wall

    KAUST Repository

    Wang, Kai Yu; Yang, Qian; Chung, Tai-Shung; Rajagopalan, Raj

    2009-01-01

    To develop high-flux and high-rejection forward osmosis (FO) membranes for water reuses and seawater desalination, we have fabricated polybenzimidazole (PBI) nanofiltration (NF) hollow fiber membranes with a thin wall and a desired pore size via non-solvent induced phase inversion and chemically cross-linking modification. The cross-linking by p-xylylene dichloride can finely tune the mean pore size and enhance the salt selectivity. High water permeation flux and improved salt selectivity for water reuses were achieved by using the 2-h modified PBI NF membrane which has a narrow pore size distribution. Cross-linking at a longer time produces even a lower salt permeation flux potentially suitable for desalination but at the expense of permeation flux due to tightened pore sizes. It is found that draw solution concentration and membrane orientations are main factors determining the water permeation flux. In addition, effects of membrane morphology and operation conditions on water and salt transport through membrane have been investigated. © 2008 Elsevier Ltd. All rights reserved.

  17. Erythrocyte membrane-coated gold nanocages for targeted photothermal and chemical cancer therapy

    Science.gov (United States)

    Zhu, Dao-Ming; Xie, Wei; Xiao, Yu-Sha; Suo, Meng; Zan, Ming-Hui; Liao, Qing-Quan; Hu, Xue-Jia; Chen, Li-Ben; Chen, Bei; Wu, Wen-Tao; Ji, Li-Wei; Huang, Hui-Ming; Guo, Shi-Shang; Zhao, Xing-Zhong; Liu, Quan-Yan; Liu, Wei

    2018-02-01

    Recently, red blood cell (RBC) membrane-coated nanoparticles have attracted much attention because of their excellent immune escapability; meanwhile, gold nanocages (AuNs) have been extensively used for cancer therapy due to their photothermal effect and drug delivery capability. The combination of the RBC membrane coating and AuNs may provide an effective approach for targeted cancer therapy. However, few reports have shown the utilization of combining these two technologies. Here, we design erythrocyte membrane-coated gold nanocages for targeted photothermal and chemical cancer therapy. First, anti-EpCam antibodies were used to modify the RBC membranes to target 4T1 cancer cells. Second, the antitumor drug paclitaxel (PTX) was encapsulated into AuNs. Then, the AuNs were coated with the modified RBC membranes. These new nanoparticles were termed EpCam-RPAuNs. We characterized the capability of the EpCam-RPAuNs for selective tumor targeting via exposure to near-infrared irradiation. The experimental results demonstrate that EpCam-RPAuNs can effectively generate hyperthermia and precisely deliver the antitumor drug PTX to targeted cells. We also validated the biocompatibility of the EpCam-RAuNs in vitro. By combining the molecularly modified targeting RBC membrane and AuNs, our approach provides a new way to design biomimetic nanoparticles to enhance the surface functionality of nanoparticles. We believe that EpCam-RPAuNs can be potentially applied for cancer diagnoses and therapies.

  18. Enhanced forward osmosis from chemically modified polybenzimidazole (PBI) nanofiltration hollow fiber membranes with a thin wall

    KAUST Repository

    Wang, Kai Yu

    2009-04-01

    To develop high-flux and high-rejection forward osmosis (FO) membranes for water reuses and seawater desalination, we have fabricated polybenzimidazole (PBI) nanofiltration (NF) hollow fiber membranes with a thin wall and a desired pore size via non-solvent induced phase inversion and chemically cross-linking modification. The cross-linking by p-xylylene dichloride can finely tune the mean pore size and enhance the salt selectivity. High water permeation flux and improved salt selectivity for water reuses were achieved by using the 2-h modified PBI NF membrane which has a narrow pore size distribution. Cross-linking at a longer time produces even a lower salt permeation flux potentially suitable for desalination but at the expense of permeation flux due to tightened pore sizes. It is found that draw solution concentration and membrane orientations are main factors determining the water permeation flux. In addition, effects of membrane morphology and operation conditions on water and salt transport through membrane have been investigated. © 2008 Elsevier Ltd. All rights reserved.

  19. Fouling of Seawater Reverse Osmosis (SWRO) Membrane: Chemical and Microbiological Characterization

    KAUST Repository

    Khan, Muhammad T.

    2013-12-01

    In spite of abundant water resources, world is suffering from the scarcity of usable water. Seawater Reverse Osmosis (SWRO) desalination technology using polymeric membranes has been recognized as a key solution to water scarcity problem. However, economic sustainability of this advanced technology is adversely impacted by the membrane fouling problem. Fouling of RO membranes is a highly studied phenomenon. However, literature is found to be lacking a detailed study on kinetic and dynamic aspects of SWRO membrane fouling. The factors that impact the fouling dynamics, i.e., pretreatment and water quality were also not adequately studied at full–scale of operation. Our experimental protocol was designed to systematically explore these fouling aspects with the objective to improve the understanding of SWRO membrane fouling mechanisms. An approach with multiple analytical techniques was developed for fouling characterization. In addition to the fouling layer characterization, feed water quality was also analysed to assess its fouling potential. Study of SWRO membrane fouling dynamics and kinetics revealed variations in relative abundance of chemical and microbial constituents of the fouling layer, over operating time. Aromatic substances, most likely humic–like substances, were observed at relatively high abundance in the initial fouling layer, followed by progressive increase in relative abundances of proteins and polysaccharides. Microbial population grown on all membranes was dominated by specific groups/species belonging to different classes of Proteobacteria phylum; however, similar to abiotic foulant, their relative abundance also changed with the biofilm age and with the position of membrane element in RO vessel. Our results demonstrated that source water quality can significantly impact the RO membrane fouling scenarios. Moreover, the major role of chlorination in the SWRO membrane fouling was highlighted. It was found that intermittent mode of chlorination

  20. Mechanical Stability of H3PO4-Doped PBI/Hydrophilic-Pretreated PTFE Membranes for High Temperature PEMFCs

    International Nuclear Information System (INIS)

    Park, Jaehyung; Wang, Liang; Advani, Suresh G.; Prasad, Ajay K.

    2014-01-01

    Graphical abstract: - Highlights: • PBI/PTFE membrane was prepared by porous PTFE with hydrophilic surface pretreatment. • The durability of the prepared PBI/PTFE membrane was compared with pure PBI, PBI with untreated PTFE, and PBI-Nafion with untreated PTFE membranes. • Accelerated durability tests and SEM showed improved durability based the PBI/PTFE membrane with pretreated PTFE. - Abstract: A novel polybenzimidazole (PBI)/poly(tetrafluoroethylene) (PTFE) composite membrane doped with phosphoric acid was fabricated for high temperature operation in a polymer electrolyte membrane (PEM) fuel cell. A hydrophilic surface pretreatment was applied to the porous PTFE matrix film to improve its interfacial adhesion to the PBI polymer, thereby avoiding the introduction of Nafion ionomer which is traditionally used as a coupling agent. The pretreated PTFE film was embedded within the composite membrane during solution-casting using 5wt% PBI/DMAc solution. The mechanical stability and durability of three types of MEAs assembled with PBI only, PBI with pretreated PTFE, and PBI-Nafion with untreated PTFE membranes were evaluated under an accelerated degradation testing protocol employing extreme temperature cycling. Degradation was characterized by recording polarization curves, hydrogen crossover, and proton resistance. Cross-sections of the membranes were examined before and after thermal cycling by scanning electron microscope. Energy-dispersive X-ray spectroscopy verified that the PBI is dispersed homogeneously in the porous PTFE matrix. Results show that the PBI composite membrane with pretreated PTFE has a lower degradation rate than the Nafion/PBI membrane with untreated PTFE. Thus, the hydrophilic pretreatment employed here greatly improved the mechanical stability of the composite membrane, which resulted in improved durability under an extreme thermal cycling regime

  1. The Effect of Covalently-Attached ATRP-Synthesized Polymers on Membrane Stability and Cytoprotection in Human Erythrocytes.

    Science.gov (United States)

    Clafshenkel, William P; Murata, Hironobu; Andersen, Jill; Creeger, Yehuda; Koepsel, Richard R; Russell, Alan J

    2016-01-01

    Erythrocytes have been described as advantageous drug delivery vehicles. In order to ensure an adequate circulation half-life, erythrocytes may benefit from protective enhancements that maintain membrane integrity and neutralize oxidative damage of membrane proteins that otherwise facilitate their premature clearance from circulation. Surface modification of erythrocytes using rationally designed polymers, synthesized via atom-transfer radical polymerization (ATRP), may further expand the field of membrane-engineered red blood cells. This study describes the fate of ATRP-synthesized polymers that were covalently attached to human erythrocytes as well as the effect of membrane engineering on cell stability under physiological and oxidative conditions in vitro. The biocompatible, membrane-reactive polymers were homogenously retained on the periphery of modified erythrocytes for at least 24 hours. Membrane engineering stabilized the erythrocyte membrane and effectively neutralized oxidative species, even in the absence of free-radical scavenger-containing polymers. The targeted functionalization of Band 3 protein by NHS-pDMAA-Cy3 polymers stabilized its monomeric form preventing aggregation in the presence of the crosslinking reagent, bis(sulfosuccinimidyl)suberate (BS3). A free radical scavenging polymer, NHS-pDMAA-TEMPO˙, provided additional protection of surface modified erythrocytes in an in vitro model of oxidative stress. Preserving or augmenting cytoprotective mechanisms that extend circulation half-life is an important consideration for the use of red blood cells for drug delivery in various pathologies, as they are likely to encounter areas of imbalanced oxidative stress as they circuit the vascular system.

  2. The Effect of Covalently-Attached ATRP-Synthesized Polymers on Membrane Stability and Cytoprotection in Human Erythrocytes.

    Directory of Open Access Journals (Sweden)

    William P Clafshenkel

    Full Text Available Erythrocytes have been described as advantageous drug delivery vehicles. In order to ensure an adequate circulation half-life, erythrocytes may benefit from protective enhancements that maintain membrane integrity and neutralize oxidative damage of membrane proteins that otherwise facilitate their premature clearance from circulation. Surface modification of erythrocytes using rationally designed polymers, synthesized via atom-transfer radical polymerization (ATRP, may further expand the field of membrane-engineered red blood cells. This study describes the fate of ATRP-synthesized polymers that were covalently attached to human erythrocytes as well as the effect of membrane engineering on cell stability under physiological and oxidative conditions in vitro. The biocompatible, membrane-reactive polymers were homogenously retained on the periphery of modified erythrocytes for at least 24 hours. Membrane engineering stabilized the erythrocyte membrane and effectively neutralized oxidative species, even in the absence of free-radical scavenger-containing polymers. The targeted functionalization of Band 3 protein by NHS-pDMAA-Cy3 polymers stabilized its monomeric form preventing aggregation in the presence of the crosslinking reagent, bis(sulfosuccinimidylsuberate (BS3. A free radical scavenging polymer, NHS-pDMAA-TEMPO˙, provided additional protection of surface modified erythrocytes in an in vitro model of oxidative stress. Preserving or augmenting cytoprotective mechanisms that extend circulation half-life is an important consideration for the use of red blood cells for drug delivery in various pathologies, as they are likely to encounter areas of imbalanced oxidative stress as they circuit the vascular system.

  3. Thin porphyrin composite membranes with enhanced organic solvent transport

    KAUST Repository

    Phuoc, Duong; Anjum, Dalaver H.; Peinemann, Klaus-Viktor; Nunes, Suzana Pereira

    2018-01-01

    Extending the stability of polymeric membranes in organic solvents is important for applications in chemical and pharmaceutical industry. Thin-film composite membranes with enhanced solvent permeance are proposed, using porphyrin as a building block

  4. Development of Improved Membranes for ROWPU Spiral-Wound Elements

    National Research Council Canada - National Science Library

    Riley, R

    2001-01-01

    .... They are: poor lack of chemical stability to oxidants such as chlorine, high fouling rates due to membrane surface roughness and high bacterial attachment counts on the membrane surface leading to biofouling...

  5. Physical and chemical stability of reconstituted and diluted dexrazoxane infusion solutions.

    Science.gov (United States)

    Zhang, Yan-Ping; Myers, Alan L; Trinh, Van A; Kawedia, Jitesh D; Kramer, Mark A; Benjamin, Robert S; Tran, Hai T

    2014-02-01

    Dexrazoxane is used clinically to prevent anthracycline-associated cardiotoxicity. Hydrolysis of dexrazoxane prior to reaching the cardiac membranes severely hampers its mode of action; therefore, degradation during the preparation and administration of intravenous dexrazoxane admixtures demands special attention. Moreover, the ongoing national shortage of one dexrazoxane formulation in the United States has forced pharmacies to dispense other commercially available dexrazoxane products. However, the manufacturers' limited stability data restrict the flexibility of dexrazoxane usage in clinical practice. The aims of this study are to determine the physical and chemical stability of reconstituted and diluted solutions of two commercially available dexrazoxane formulations. The stability of two dexrazoxane products, brand and generic name, in reconstituted and intravenous solutions stored at room temperature without light protection in polyvinyl chloride bags was determined. The concentrations of dexrazoxane were measured at predetermined time points up to 24 h using a validated reversed phase high-performance liquid chromatography with ultraviolet detection assay. Brand (B-) and generic (G-) dexrazoxane products, reconstituted in either sterile water or 0.167 M sodium lactate (final concentration of 10 mg/mL), were found stable for at least to 8 h. Infusion solutions of B-dexrazoxane, prepared according to each manufacturer's directions, were stable for at least 24 h and 8 h at 1 mg/mL and 3 mg/mL, respectively. Infusion solutions of G-dexrazoxane, prepared in either 5% dextrose or 0.9% sodium chloride following the manufacturer's guidelines, were also stable for at least 24 h and 8 h at 1 mg/mL and 3 mg/mL, respectively. All tested solutions were found physically stable up to 24 h at room temperature. The stability of dexrazoxane infusion solutions reported herein permits advance preparation of dexrazoxane intravenous admixtures, facilitating

  6. Research results on productivity stabilization by ultrasonic camera (plant with membrane ceramic elements during vine processing

    Directory of Open Access Journals (Sweden)

    V. T. Antufyev

    2016-01-01

    Full Text Available The article describes solutions to the problems of declining productivity of ceramic membrane elements for wine processing on the final manufacturing phase. A relative stabilization of filtration velocity, venting efficiency and wine lightening were experimentally confirmed during contacts with oscillation waves of ultrasonic transmitter on the ceramic filter. Which significantly reduced the cost of various preservatives to increase periods storage. To study the processes of wine processing by the proposed method it was made an experimental installation on the basis of pilot machine MRp-1/2 for bottling of quiet liquids and an ultrasonic device "Volna– M" UZTA-1/22-OM with a firmly, waveguide which transmits sound, fixed filter frame on the ultrasound emitter. To stabilize the performance of ultrasonic units with ceramic membrane elements without quality deterioration of wines it was empirically determined rational parameters of power of ultrasound input and pressure in the system. The given derived dependencies and graphs allow to define the time of relatively stable operating filter regime. It was revealed a significant cost reduction on filtration, as it allows escape from the contamination of the product by various preservatives, and increasing of storage duration in a sealed container during aseptic filling without a thermal sterilization. Ultrasonic emitter contact by superposition wave vibrations on the ceramic filter increases not only the efficiency of gas removal, but also improves the organoleptic characteristics, stabilizes the filters, improves their productivity. Gas removal creates unfavorable conditions for development of the yeast, which in turn increases the shelf life of semisweet wine.

  7. Both solubility and chemical stability of curcumin are enhanced by solid dispersion in cellulose derivative matrices.

    Science.gov (United States)

    Li, Bin; Konecke, Stephanie; Wegiel, Lindsay A; Taylor, Lynne S; Edgar, Kevin J

    2013-10-15

    Amorphous solid dispersions (ASD) of curcumin (Cur) in cellulose derivative matrices, hydroxypropylmethylcellulose acetate succinate (HPMCAS), carboxymethylcellulose acetate butyrate (CMCAB), and cellulose acetate adipate propionate (CAAdP) were prepared in order to investigate the structure-property relationship and identify polymer properties necessary to effectively increase Cur aqueous solution concentration. XRD results indicated that all investigated solid dispersions were amorphous, even at a 9:1 Cur:polymer ratio. Both stability against crystallization and Cur solution concentration from these ASDs were significantly higher than those from physical mixtures and crystalline Cur. Remarkably, curcumin was also stabilized against chemical degradation in solution. Chemical stabilization was polymer-dependent, with stabilization in CAAdP>CMCAB>HPMCAS>PVP, while matrices enhanced solution concentration as PVP>HPMCAS>CMCAB≈CAAdP. HPMCAS/Cur dispersions have useful combinations of pH-triggered release profile, chemical stabilization, and strong enhancement of Cur solution concentration. Copyright © 2013 Elsevier Ltd. All rights reserved.

  8. Peptide insertion, positioning, and stabilization in a membrane: insight from an all-atom molecular dynamics simulation.

    Science.gov (United States)

    Babakhani, Arneh; Gorfe, Alemayehu A; Gullingsrud, Justin; Kim, Judy E; Andrew McCammon, J

    Peptide insertion, positioning, and stabilization in a model membrane are probed via an all-atom molecular dynamics (MD) simulation. One peptide (WL5) is simulated in each leaflet of a solvated dimyristoylglycero-3-phosphate (DMPC) membrane. Within the first 5 ns, the peptides spontaneously insert into the membrane and then stabilize during the remaining 70 ns of simulation time. In both leaflets, the peptides localize to the membrane interface, and this localization is attributed to the formation of peptide-lipid hydrogen bonds. We show that the single tryptophan residue in each peptide contributes significantly to these hydrogen bonds; specifically, the nitrogen heteroatom of the indole ring plays a critical role. The tilt angles of the indole rings relative to the membrane normal in the upper and lower leaflets are approximately 26 degrees and 54 degrees , respectively. The tilt angles of the entire peptide chain are 62 degrees and 74 degrees . The membrane induces conformations of the peptide that are characteristic of beta-sheets, and the peptide enhances the lipid ordering in the membrane. Finally, the diffusion rate of the peptides in the membrane plane is calculated (based on experimental peptide concentrations) to be approximately 6 A(2)/ns, thus suggesting a 500 ns time scale for intermolecular interactions.

  9. Removal of trace organic chemicals and performance of a novel hybrid ultrafiltration-osmotic membrane bioreactor.

    Science.gov (United States)

    Holloway, Ryan W; Regnery, Julia; Nghiem, Long D; Cath, Tzahi Y

    2014-09-16

    A hybrid ultrafiltration-osmotic membrane bioreactor (UFO-MBR) was investigated for over 35 days for nutrient and trace organic chemical (TOrC) removal from municipal wastewater. The UFO-MBR system uses both ultrafiltration (UF) and forward osmosis (FO) membranes in parallel to simultaneously extract clean water from an activated sludge reactor for nonpotable (or environmental discharge) and potable reuse, respectively. In the FO stream, water is drawn by osmosis from activated sludge through an FO membrane into a draw solution (DS), which becomes diluted during the process. A reverse osmosis (RO) system is then used to reconcentrate the diluted DS and produce clean water suitable for direct potable reuse. The UF membrane extracts water, dissolved salts, and some nutrients from the system to prevent their accumulation in the activated sludge of the osmotic MBR. The UF permeate can be used for nonpotable reuse purposes (e.g., irrigation and toilet flushing). Results from UFO-MBR investigation illustrated that the chemical oxygen demand, total nitrogen, and total phosphorus removals were greater than 99%, 82%, and 99%, respectively. Twenty TOrCs were detected in the municipal wastewater that was used as feed to the UFO-MBR system. Among these 20 TOrCs, 15 were removed by the hybrid UFO-MBR system to below the detection limit. High FO membrane rejection was observed for all ionic and nonionic hydrophilic TOrCs and lower rejection was observed for nonionic hydrophobic TOrCs. With the exceptions of bisphenol A and DEET, all TOrCs that were detected in the DS were well rejected by the RO membrane. Overall, the UFO-MBR can operate sustainably and has the potential to be utilized for direct potable reuse applications.

  10. Plant plasma membrane aquaporins in natural vesicles as potential stabilizers and carriers of glucosinolates.

    Science.gov (United States)

    Martínez-Ballesta, Maria Del Carmen; Pérez-Sánchez, Horacio; Moreno, Diego A; Carvajal, Micaela

    2016-07-01

    Their biodegradable nature and ability to target cells make biological vesicles potential nanocarriers for bioactives delivery. In this work, the interaction between proteoliposomes enriched in aquaporins derived from broccoli plants and the glucosinolates was evaluated. The vesicles were stored at different temperatures and their integrity was studied. Determination of glucosinolates, showed that indolic glucosinolates were more sensitive to degradation in aqueous solution than aliphatic glucosinolates. Glucoraphanin was stabilized by leaf and root proteoliposomes at 25°C through their interaction with aquaporins. An extensive hydrogen bond network, including different aquaporin residues, and hydrophobic interactions, as a consequence of the interaction between the linear alkane chain of glucoraphanin and Glu31 and Leu34 protein residues, were established as the main stabilizing elements. Combined our results showed that plasma membrane vesicles from leaf and root tissues of broccoli plants may be considered as suitable carriers for glucosinolate which stabilization can be potentially attributed to aquaporins. Copyright © 2016 Elsevier B.V. All rights reserved.

  11. Physical-chemical hydrodynamics of the processes of sorption-membrane technology of LRW treatment

    International Nuclear Information System (INIS)

    Alexander D Efanov; Pyotr N Martynov; Yuri D Boltoev; Ivan V Yagodkin; Nataliya G Bogdanovich; Sergey S Skvortsov; Alexander R Sokolovsky; Elena V Ignatova; Gennady V Grigoriev; Vitaly V Grigorov

    2005-01-01

    Full text of publication follows: Liquid radioactive NPP waste is generated, when radioactive water is collected and mixed from various routine and non-routine process measures being performed in accordance with the operating regulations of reactor units with water coolant. The main sources of LRW are the primary loop water coolant, deactivation, regeneration and rinse waters, waste laundry and showers water producing the initial averaged LRW as well as spent fuel element cooling pond water and water of biological protection tanks. LRW handling can be substantially advanced, in particular, through development and introduction of the non-conventional sorption-membrane technology of NPP LRW treatment, being developed at SSC RF IPPE. This technology makes use of natural inorganic sorbents (tripolite, zeolite, ion-exchange materials) and filtering nano-structured metallic and ceramic membranes (titanium, zirconium, chromium and other or their oxides, carbides and nitrides). The efficiency of the sorption membrane technology is associated just with the investigation of the physical-chemical processes of sorption, coagulation and sedimentation under the conditions of forced and free convection occurring in LRW. Besides, it is necessary to take into consideration that the hydrodynamics of the flows of LRW being decontaminated by membrane filtration depends on the structure and composition of the porous composition pare 'nano-structured membrane-substrate'. Neglecting these peculiarities can result in drastic reduction of the time of stable LRW filtration, reduction of the operability resource of filtration systems or in quick mechanical destruction of porous materials. The paper presents the investigation results on: -the effect of the convection flows being generated by air bubbling or LRW stirring by agitator on the static sorption conditions (sorption time, medium pH, sorbent dispersity, sorbent concentration in liquid medium) and on the efficiency of extraction by

  12. Investigation of the chemical mechanisms involved in the electropulsation of membranes at the molecular level.

    Science.gov (United States)

    Breton, Marie; Mir, Lluis M

    2018-02-01

    The chemical consequences of electropulsation on giant unilamellar vesicles (GUVs), in particular the possible oxidation of unsaturated phospholipids, have been investigated by mass spectrometry, flow cytometry and absorbance methods. Pulse application induced oxidation of the GUV phospholipids and the oxidation level depended on the duration of the pulse. Light and O 2 increased the level of pulse-induced lipid peroxidation whereas the presence of antioxidants either in the membrane or in the solution completely suppressed peroxidation. Importantly, pulse application did not create additional reactive oxygen species (ROS) in GUV-free solution. Lipid peroxidation seems to result from a facilitation of the lipid peroxidation by the ROS already present in the solution before pulsing, not from a direct pulse-induced peroxidation. The pulse would facilitate the entrance of ROS in the core of the membrane, allowing the contact between ROS and lipid chains and provoking the oxidation. Our findings demonstrate that the application of electric pulses on cells could induce the oxidation of the membrane phospholipids since cell membranes contain unsaturated lipids. The chemical consequences of electropulsation will therefore have to be taken into account in future biomedical applications of electropulsation since oxidized phospholipids play a key role in many signaling pathways and diseases. Copyright © 2017 Elsevier B.V. All rights reserved.

  13. How Do Polyethylene Glycol and Poly(sulfobetaine) Hydrogel Layers on Ultrafiltration Membranes Minimize Fouling and Stay Stable in Cleaning Chemicals?

    KAUST Repository

    Le, Ngoc Lieu

    2017-05-18

    We compare the efficiency of grafting polyethylene glycol (PEG) and poly(sulfobetaine) hydrogel layer on poly(ether imide) (PEI) hollow-fiber ultrafiltration membrane surfaces in terms of filtration performance, fouling minimization and stability in cleaning solutions. Two previously established different methods toward the two different chemistries (and both had already proven to be suited to reduce fouling significantly) are applied to the same PEI membranes. The hydrophilicity of PEI membranes is improved by the modification, as indicated by the change of contact angle value from 89° to 68° for both methods, due to the hydration layer formed in the hydrogel layers. Their pure water flux declines because of the additional permeation barrier from the hydrogel layers. However, these barriers increase protein rejection. In the exposure at a static condition, grafting PEG or poly(sulfobetaine) reduces protein adsorption to 23% or 11%, respectively. In the dynamic filtration, the hydrogel layers minimizes the flux reduction and increases the reversibility of fouling. Compared to the pristine PEI membrane that can recover its flux to 42% after hydraulic cleaning, the PEG and poly(sulfobetaine) grafted membranes can recover their flux up to 63% and 94%, respectively. Stability tests show that the poly(sulfobetaine) hydrogel layer is stable in acid, base and chlorine solutions, whereas the PEG hydrogel layer suffers alkaline hydrolysis in base and oxidation in chlorine conditions. With its chemical stability and pronounced capability of minimizing fouling, especially irreversible fouling, protective poly(sulfobetaine) hydrogel layers have great potential for various membrane-based applications.

  14. Probing nanomechanical interaction at the interface between biological membrane and potentially toxic chemical.

    Science.gov (United States)

    Lim, Chanoong; Park, Sohee; Park, Jinwoo; Ko, Jina; Lee, Dong Woog; Hwang, Dong Soo

    2018-04-12

    Various xenobiotics interact with biological membranes, and precise evaluations of the molecular interactions between them are essential to foresee the toxicity and bioavailability of existing or newly synthesized molecules. In this study, surface forces apparatus (SFA) measurement and Langmuir trough based tensiometry are performed to reveal nanomechanical interaction mechanisms between potential toxicants and biological membranes for ex vivo toxicity evaluation. As a toxicant, polyhexamethylene guanidine (PHMG) was selected because PHMG containing humidifier disinfectant and Vodka caused lots of victims in both S. Korea and Russia, respectively, due to the lack of holistic toxicity evaluation of PHMG. Here, we measured strong attraction (Wad ∼4.2 mJ/m 2 ) between PHMG and head group of biological membranes while no detectable adhesion force between the head group and control molecules was measured. Moreover, significant changes in π-A isotherm of 1,2-Dipalmitoyl-sn-glycero-3-phosphatidylcholine (DPPC) monolayers were measured upon PHMG adsorption. These results indicate PHMG strongly binds to hydrophilic group of lipid membranes and alters the structural and phase behavior of them. More importantly, complementary utilization of SFA and Langmuir trough techniques are found to be useful to predict the potential toxicity of a chemical by evaluating the molecular interaction with biological membranes, the primary protective barrier for living organisms. Copyright © 2018 Elsevier B.V. All rights reserved.

  15. Enhanced stability of Zr-doped Ba(CeTb)O(3-δ)-Ni cermet membrane for hydrogen separation.

    Science.gov (United States)

    Wei, Yanying; Xue, Jian; Fang, Wei; Chen, Yan; Wang, Haihui; Caro, Jürgen

    2015-07-25

    A mixed protonic and electronic conductor material BaCe(0.85)Tb(0.05)Zr(0.1)O(3-δ) (BCTZ) is prepared and a Ni-BCTZ cermet membrane is synthesized for hydrogen separation. Stable hydrogen permeation fluxes can be obtained for over 100 h through the Ni-BCTZ membrane in both dry and humid conditions, which exhibits an excellent stability compared with Ni-BaCe(0.95)Tb(0.05)O(3-δ) membrane due to the Zr doping.

  16. Study on stability of a-SiCOF films deposited by plasma enhanced chemical vapor deposition

    International Nuclear Information System (INIS)

    Ding Shijin; Zhang Qingquan; Wang Pengfei; Zhang Wei; Wang Jitao

    2001-01-01

    Low-dielectric-constant a-SiCOF films have been prepared from TEOS, C 4 F 8 and Ar by using plasma enhanced chemical vapor deposition method. With the aid of X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared spectroscopy (FTIR), the chemical bonding configuration, thermal stability and resistance to water of the films are explored

  17. Insertion of Neurotransmitters into a Lipid Bilayer Membrane and Its Implication on Membrane Stability: A Molecular Dynamics Study.

    Science.gov (United States)

    Shen, Chun; Xue, Minmin; Qiu, Hu; Guo, Wanlin

    2017-03-17

    The signaling molecules in neurons, called neurotransmitters, play an essential role in the transportation of neural signals, during which the neurotransmitters interact with not only specific receptors, but also cytomembranes, such as synaptic vesicle membranes and postsynaptic membranes. Through extensive molecular dynamics simulations, the atomic-scale insertion dynamics of typical neurotransmitters, including methionine enkephalin (ME), leucine enkephalin (LE), dopamine (DA), acetylcholine (ACh), and aspartic acid (ASP), into lipid bilayers is investigated. The results show that the first three neurotransmitters (ME, LE, and DA) are able to diffuse freely into both 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC) and 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphoethanolamine (POPE) membranes, and are guided by the aromatic residues Tyr and Phe. Only a limited number of these neurotransmitters are allowed to penetrate into the membrane, which suggests an intrinsic mechanism by which the membrane is protected from being destroyed by excessive inserted neurotransmitters. After spontaneous insertion, the neurotransmitters disturb the surrounding phospholipids in the membrane, as indicated by the altered distribution of components in lipid leaflets and the disordered lipid tails. In contrast, the last two neurotransmitters (ACh and ASP) cannot enter the membrane, but instead always diffuse freely in solution. These findings provide an understanding at the atomic level of how neurotransmitters interact with the surrounding cytomembrane, as well as their impact on membrane behavior. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  18. Stability of milk fat globule membrane proteins toward human enzymatic gastrointestinal digestion.

    Science.gov (United States)

    Le, T T; Van de Wiele, T; Do, T N H; Debyser, G; Struijs, K; Devreese, B; Dewettinck, K; Van Camp, J

    2012-05-01

    The milk fat globule membrane (MFGM) fraction refers to the thin film of polar lipids and membrane proteins that surrounds fat globules in milk. It is its unique biochemical composition that renders MFGM with some beneficial biological activities, such as anti-adhesive effects toward pathogens. However, a prerequisite for the putative bioactivity of MFGM is its stability during gastrointestinal digestion. We, therefore, subjected MFGM material, isolated from raw milk, to an in vitro enzymatic gastrointestinal digestion. Sodium dodecyl sulfate PAGE, in combination with 2 staining methods, Coomassie Blue and periodic acid Schiff staining, was used to evaluate polypeptide patterns of the digest, whereas mass spectrometry was used to confirm the presence of specific MFGM proteins. Generally, it was observed that glycoproteins showed higher resistance to endogenous proteases compared with non-glycosylated proteins. Mucin 1 displayed the highest resistance to digestion and a considerable part of this protein was still detected at its original molecular weight after gastric and small intestine digestion. Cluster of differentiation 36 was also quite resistant to pepsin. A significant part of periodic acid Schiff 6/7 survived the gastric digestion, provided that the lipid moiety was not removed from the MFGM material. Overall, MFGM glycoproteins are generally more resistant to gastrointestinal digestion than serum milk proteins and the presence of lipids, besides glycosylation, may protect MFGM glycoproteins from gastrointestinal digestion. This gastrointestinal stability makes MFGM glycoproteins amenable to further studies in which their putative health-promoting effects can be explored. Copyright © 2012 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

  19. Static Magnetic Field Attenuates Lipopolysaccharide-Induced Inflammation in Pulp Cells by Affecting Cell Membrane Stability

    Directory of Open Access Journals (Sweden)

    Sung-Chih Hsieh

    2015-01-01

    Full Text Available One of the causes of dental pulpitis is lipopolysaccharide- (LPS- induced inflammatory response. Following pulp tissue inflammation, odontoblasts, dental pulp cells (DPCs, and dental pulp stem cells (DPSCs will activate and repair damaged tissue to maintain homeostasis. However, when LPS infection is too serious, dental repair is impossible and disease may progress to irreversible pulpitis. Therefore, the aim of this study was to examine whether static magnetic field (SMF can attenuate inflammatory response of dental pulp cells challenged with LPS. In methodology, dental pulp cells were isolated from extracted teeth. The population of DPSCs in the cultured DPCs was identified by phenotypes and multilineage differentiation. The effects of 0.4 T SMF on DPCs were observed through MTT assay and fluorescent anisotropy assay. Our results showed that the SMF exposure had no effect on surface markers or multilineage differentiation capability. However, SMF exposure increases cell viability by 15%. In addition, SMF increased cell membrane rigidity which is directly related to higher fluorescent anisotropy. In the LPS-challenged condition, DPCs treated with SMF demonstrated a higher tolerance to LPS-induced inflammatory response when compared to untreated controls. According to these results, we suggest that 0.4 T SMF attenuates LPS-induced inflammatory response to DPCs by changing cell membrane stability.

  20. Stress proteins in lymphocytes: Membrane stabilization does not affect the heat shock response

    International Nuclear Information System (INIS)

    Hughes, C.S.; Repasky, E.A.; Subjeck, J.R.

    1987-01-01

    Temperatures which have been used to induce heat shock proteins (hsps) have been at the upper physiologic limit or well above this limit. In addition, little attention has been given to the effects of physiologic heat exposures on hsp induction in lymphocytes. The author examined temperatures between 39 0 C and 41 0 C on protein synthesis in the following lymphoid cell lines and cells: BDK, EL-4, JM, DO.11, and in dispersed lymph nodes and thymic tissues. In these studies, 39.5 0 appears to be the threshold for hsp induction (as distinguished by gel electrophoresis). At this temperature the induction of the major hsps at 70 and 89 kDa are observed. Hsp 89 appears to be the most strongly induced in all cells examined. In JM cells, a human cell line, heat shock also induces hsp 68, the non-constitutive hsp at this size. These temperatures do not depress normal levels of protein synthesis. When stearic acid or cholesterol was added to lymphocyte cultures prior to heating (which stabilize membranes), hsp induction appears to occur in a manner indistinguishable from cells heated in normal media. This suggests that membrane fluidity (as influenced by these agents) does not affect or depress the heat shock response in these cells. Finally, the authors observed that 2-deoxyglucose and other inducers of glucose regulated proteins in fibroblasts also induce the major glucose regulated proteins in lymphocytes

  1. Chemical stability of copper-canisters in deep repository

    International Nuclear Information System (INIS)

    Ahonen, L.

    1995-12-01

    The spent fuel from Finnish nuclear reactors is planned to be encapsulated in thick-walled copper-iron canisters and placed deep into the bedrock. The copper wall of the canister provides a long-time shield against corrosion, preventing the high-level nuclear fuel from contact with ground water. In the report, stability of metallic copper and its possible corrosion reactions in the conditions of deep bedrock are evaluated by means of thermo-dynamic calculations. (90 refs., 28 figs., 11 tabs.)

  2. Vibration and Stability of 3000-hp, Titanium Chemical Process Blower

    Directory of Open Access Journals (Sweden)

    Les Gutzwiller

    2003-01-01

    Full Text Available This 74-in-diameter blower had an overhung rotor design of titanium construction, operating at 50 pounds per square inch gauge in a critical chemical plant process. The shaft was supported by oil-film bearings and was directdriven by a 3000-hp electric motor through a metal disk type of coupling. The operating speed was 1780 rpm. The blower shaft and motor shaft motion was monitored by Bently Nevada proximity probes and a Model 3100 monitoring system.

  3. Modulation of erythrocyte membrane mechanical stability by 2,3-diphosphoglycerate in the neonatal poikilocytosis/elliptocytosis syndrome.

    OpenAIRE

    Mentzer, W C; Iarocci, T A; Mohandas, N; Lane, P A; Smith, B; Lazerson, J; Hays, T

    1987-01-01

    To explain the transient anemia and poikilocytosis seen during infancy in hereditary elliptocytosis (HE), we resealed erythrocyte (RBC) ghosts from affected children or their elliptocytic parents with 2,3-diphosphoglycerate (DPG) (0-8 mM), a compound that dissociates membrane skeletons, then measured ghost mechanical stability in the ektacytometer. Without added 2,3-DPG, ghost mechanical stability was subnormal in infantile poikilocytosis (IP) and HE but was even more abnormal in hereditary p...

  4. Structure and stability of the spinach aquaporin SoPIP2;1 in detergent micelles and lipid membranes.

    Directory of Open Access Journals (Sweden)

    Inés Plasencia

    Full Text Available BACKGROUND: SoPIP2;1 constitutes one of the major integral proteins in spinach leaf plasma membranes and belongs to the aquaporin family. SoPIP2;1 is a highly permeable and selective water channel that has been successfully overexpressed and purified with high yields. In order to optimize reconstitution of the purified protein into biomimetic systems, we have here for the first time characterized the structural stability of SoPIP2;1. METHODOLOGY/PRINCIPAL FINDING: We have characterized the protein structural stability after purification and after reconstitution into detergent micelles and proteoliposomes using circular dichroism and fluorescence spectroscopy techniques. The structure of SoPIP2;1 was analyzed either with the protein solubilized with octyl-β-D-glucopyranoside (OG or reconstituted into lipid membranes formed by E. coli lipids, diphytanoylphosphatidylcholine (DPhPC, or reconstituted into lipid membranes formed from mixtures of 1-palmitoyl-2-oleoyl-phosphatidylcholine (POPE, 1-palmitoyl-2oleoyl-phosphatidylethanolamine (POPE, 1-palmitoyl-2-oleoyl-phosphatidylserine (POPS, and ergosterol. Generally, SoPIP2;1 secondary structure was found to be predominantly α-helical in accordance with crystallographic data. The protein has a high thermal structural stability in detergent solutions, with an irreversible thermal unfolding occurring at a melting temperature of 58°C. Incorporation of the protein into lipid membranes increases the structural stability as evidenced by an increased melting temperature of up to 70°C. CONCLUSION/SIGNIFICANCE: The results of this study provide insights into SoPIP2;1 stability in various host membranes and suggest suitable choices of detergent and lipid composition for reconstitution of SoPIP2;1 into biomimetic membranes for biotechnological applications.

  5. Polyvinylpyrrolidone-based semi-interpenetrating polymer networks as highly selective and chemically stable membranes for all vanadium redox flow batteries

    Science.gov (United States)

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

    2016-09-01

    Vanadium redox flow batteries (VRFBs) with their high flexibility in configuration and operation, as well as long cycle life are competent for the requirement of future energy storage systems. Nevertheless, due to the application of perfluorinated membranes, VRFBs are plagued by not only the severe migration issue of vanadium ions, but also their high cost. Herein, we fabricate semi-interpenetrating polymer networks (SIPNs), consisting of cross-linked polyvinylpyrrolidone (PVP) and polysulfone (PSF), as alternative membranes for VRFBs. It is demonstrated that the PVP-based SIPNs exhibit extremely low vanadium permeabilities, which contribute to the well-established hydrophilic/hydrophobic microstructures and the Donnan exclusion effect. As a result, the coulombic efficiencies of VRFBs with PVP-based SIPNs reach almost 100% at 40 mA cm-2 to 100 mA cm-2; the energy efficiencies are more than 3% higher than those of VRFBs with Nafion 212. More importantly, the PVP-based SIPNs exhibit a superior chemical stability, as demonstrated both by an ex situ immersion test and continuously cycling test. Hence, all the characterizations and performance tests reported here suggest that PVP-based SIPNs are a promising alternative membrane for redox flow batteries to achieve superior cell performance and excellent cycling stability at the fraction of the cost of perfluorinated membranes.

  6. chemical studies on the extraction of certain metal ions from aqueous solution by liquid emulsion membrane

    International Nuclear Information System (INIS)

    Kassem, A.T.

    2011-01-01

    In this thesis four systems are addressed related to the use of liquid emulsion membranes (ELM) based on Co(III)dicarbiolide and. The system was dedicated for permeation of cadmium , cobalt Nickel and lead for use of this system for preconcentration and separation of cadmium, cobalt, nickel and lead. The work carried out in this thesis is presented in three parts, namely; introduction, experimental and results and discussion.The first chapter is the introduction which includes aim of work, basic concepts of liquid membranes; liquid emulsion membranes; different models of emulsion permeation, literature survey of extraction chemistry of cadmium, cobalt, nickel and lead. Chapter two includes the experimental part. In this part detailed outlines on the chemicals and different elements used were given. Different instruments as well as analytical techniques were outlines. The preparation of liquid emulsion membrane and the permeation techniques were presented in details. The third chapter deals with the results and discussion. This chapter is divided into four main parts, the four parts is concerned with cadmium/Co(III) dicarbolide/NTA, EDTA, DPTA and DCTA systems. In this part the permeation of Cd(II) aqueous solution by the membrane used was experimented based on liquid-liquid extraction studies of cadmium from different sodium chloride molarities (from 0.01 to 0.1 M) by 0.01 M Cobalt(III) dicarbolides. It was found that the extraction of with cadmium is higher following in the first system, the permeation of the toxic elements, Cd(II) from HCl/sodium chloride medium was carried out using liquid emulsion membrane containing Co(III)dicarbiolide in xylene as carrier, Spain 80/ Spain 85(1:3) as surfactant and NTA, EDTA, DPTA and DCTA as a stripping solutions.

  7. Proton-sensing transistor systems for detecting ion leakage from plasma membranes under chemical stimuli.

    Science.gov (United States)

    Imaizumi, Yuki; Goda, Tatsuro; Schaffhauser, Daniel F; Okada, Jun-Ichi; Matsumoto, Akira; Miyahara, Yuji

    2017-03-01

    The membrane integrity of live cells is routinely evaluated for cytotoxicity induced by chemical or physical stimuli. Recent progress in bioengineering means that high-quality toxicity validation is required. Here, we report a pH-sensitive transistor system developed for the continuous monitoring of ion leakage from cell membranes upon challenge by toxic compounds. Temporal changes in pH were generated with high reproducibility via periodic flushing of HepG2 cells on a gate insulator of a proton-sensitive field-effect transistor with isotonic buffer solutions with/without NH 4 Cl. The pH transients at the point of NH 4 Cl addition/withdrawal originated from the free permeation of NH 3 across the semi-permeable plasma membranes, and the proton sponge effect produced by the ammonia equilibrium. Irreversible attenuation of the pH transient was observed when the cells were subjected to a membrane-toxic reagent. Experiments and simulations proved that the decrease in the pH transient was proportional to the area of the ion-permeable pores on the damaged plasma membranes. The pH signal was correlated with the degree of hemolysis produced by the model reagents. The pH assay was sensitive to the formation of molecularly sized pores that were otherwise not measurable via detection of the leakage of hemoglobin, because the hydrodynamic radius of hemoglobin was greater than 3.1nm in the hemolysis assay. The pH transient was not disturbed by inherent ion-transporter activity. The ISFET assay was applied to a wide variety of cell types. The system presented here is fast, sensitive, practical and scalable, and will be useful for validating cytotoxins and nanomaterials. The plasma membrane toxicity and hemolysis are widely and routinely evaluated in biomaterials science and biomedical engineering. Despite the recent development of a variety of methods/materials for efficient gene/drug delivery systems to the cytosol, the methodologies for safety validation remain unchanged in

  8. Preparation of Cu{sub 2}O nanowire-blended polysulfone ultrafiltration membrane with improved stability and antimicrobial activity

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Zehai; Ye, Shuaiju; Fan, Zheng; Ren, Fanghua; Gao, Congjie [Zhejiang University of Technology, Institute of Oceanic and Environmental Chemical Engineering, College of Chemical Engineering and Material Science and College of Ocean, and State Key Lab Breeding Base of Green Chemical Synthesis Technology and Zhejiang Collaborative Innovation Center of Membrane Separation and Water Treatment (China); Li, Qingbiao; Li, Guoqing [Quanzhou Normal University, College of Chemistry and Life Science (China); Zhang, Guoliang, E-mail: membrane86571@163.com, E-mail: guoliangz@zjut.edu.cn [Zhejiang University of Technology, Institute of Oceanic and Environmental Chemical Engineering, College of Chemical Engineering and Material Science and College of Ocean, and State Key Lab Breeding Base of Green Chemical Synthesis Technology and Zhejiang Collaborative Innovation Center of Membrane Separation and Water Treatment (China)

    2015-10-15

    Polysulfone (PSF) membranes have been widely applied in water and wastewater treatment, food-processing and biomedical fields. In this study, we report the preparation of modified PSF membranes by blending PSF with Cu{sub 2}O nanowires (NWs) to improve their stability and antifouling activity. Synthesis of novel Cu{sub 2}O NWs/PSF-blended ultrafiltration membrane was achieved via phase inversion method by dispersing one-dimensional Cu{sub 2}O nanowires in PSF casting solutions. Various techniques such as XRD, SEM, TEM, and EDS were applied to characterize and investigate the properties of nanowires and membranes. The introduced Cu{sub 2}O nanowires can firmly be restricted into micropores of PSF membranes, and therefore, they can effectively prevent the serious leaking problem of inorganic substances in separation process. The blended PSF membranes also provided enhanced antimicrobial activity and superior permeation property compared to pure PSF membrane. The overall work can not only provide a new way for preparation of novel blended membranes with multidimensional nanomaterials, but can also be beneficial to solve the annoying problem of biofouling.

  9. Partially stabilized zirconia (PSZ) - what's in it for chemical engineers?

    International Nuclear Information System (INIS)

    Michelmore, A.G.

    1988-01-01

    Partial Stabilized Zirconia (PSZ) is a non-brittle ceramic material with virtually the same modulus of elasticity, Poisson's ratio, tensile strength, and co-efficient of thermal expansion as steel, coupled with low thermal conductivity, low electrical conductivity, high hardness, non-magnetic properties and high corrosion resistance. Uses are in a wide variety of applications such as automotive, computer, hot copper extrusion dies, delicate laboratory equipment, mining spigots and injection moulding gates for plastic. Applications previously thought to be impossible for ceramics such as in high thermal and/or mechanical shock situations are now possible with benefits such as longer life, reduced maintenance costs, less downtime, lower stock inventory and improved productivity. Examples given here include downhole pump check valves in the oil and gas industry, dry bearings in the mining industry and plungers for pumping tomato paste in the food processing industry. A brief comparison is made of other PSZs and Nilcra PSZ. 1 fig

  10. Environmental Decontamination of a Chemical Warfare Simulant Utilizing a Membrane Vesicle-Encapsulated Phosphotriesterase.

    Science.gov (United States)

    Alves, Nathan J; Moore, Martin; Johnson, Brandy J; Dean, Scott N; Turner, Kendrick B; Medintz, Igor L; Walper, Scott A

    2018-05-09

    While technologies for the remediation of chemical contaminants continue to emerge, growing interest in green technologies has led researchers to explore natural catalytic mechanisms derived from microbial species. One such method, enzymatic degradation, offers an alternative to harsh chemical catalysts and resins. Recombinant enzymes, however, are often too labile or show limited activity when challenged with nonideal environmental conditions that may vary in salinity, pH, or other physical properties. Here, we demonstrate how phosphotriesterase encapsulated in a bacterial outer membrane vesicle can be used to degrade the organophosphate chemical warfare agent (CWA) simulant paraoxon in environmental water samples. We also carried out remediation assays on solid surfaces, including glass, painted metal, and fabric, that were selected as representative materials, which could potentially be contaminated with a CWA.

  11. Further observations on sensitization of chemically stabilized stainless steels

    International Nuclear Information System (INIS)

    Samans, C.H.; Kinoshita, K.; Matsushima, I.

    1977-01-01

    Niobium additions to an 18Cr:8Ni type matrix reduce carbon solubility to such an extent that any ''solution treatment'' below 1150 0 C causes stabilization. Consequently, no Cr 23 C 6 precipitates at lower temperatures to sensitize the structure. Further observations on Type 321 suggest that two types of TiC precipitate from solid solution in an 18 : 8 type matrix. The size of the TiC nucleus decreases with the precipitating temperature. Above 1050 to 1100 0 C the initial TiC is probably incoherent, large enough to be stable, and resistant to ferric sulfate-sulfuric acid solution. Below 1050 to 1100 0 C the initial TiC, known as ''dot TiC'' or ''TiC on dislocations,'' is probably coherent, not large enough to be stable without further growth, and not resistant to ferric sulfate-sulfuric acid solution. During holding at temperatures below 1050 to 1100 0 C, stabilization occurs as the TiC on dislocations agglomerates to larger, incoherent particles. The time required increases as the temperature decreases down to the minimum TiC nucleation temperature near 610 0 C. Cold work makes it easier for the coherent particles to become incoherent, in effect facilitating approach to equilibrium carbon solubility at any temperature. Once chromium carbide forms, dissolved titanium eventually reacts with it, forming TiC and releasing chromium to desensitize the structure. This reaction can occur, given sufficient time for titanium diffusion, at any temperature at which chromium carbide nucleates. It is much more rapid than back diffusion of chromium from the matrix

  12. Study to determine the technical and economic feasibility of reclaiming chemicals used in micellar polymer and low tension surfactant flooding. Final report. [Ultrafiltration membranes and reverse osmosis membranes

    Energy Technology Data Exchange (ETDEWEB)

    Stephens, R.H.; Himmelblau, A.; Donnelly, R.G.

    1978-02-01

    Energy Resources Company has developed a technology for use with enhanced oil recovery to achieve emulsion breaking and surfactant recovery. By using ultrafiltration membranes, the Energy Resources Company process can dewater an oil-in-water type emulsion expected from enhanced oil recovery projects to the point where the emulsion can be inverted and treated using conventional emulsion-treating equipment. By using a tight ultrafiltration membrane or a reverse osmosis membrane, the Energy Resources Company process is capable of recovering chemicals such as surfactants used in micellar polymer flooding.

  13. An Untrodden Path: Versatile Fabrication of Self-Supporting Polymer-Stabilized Percolation Membranes (PSPMs) for Gas Separation.

    Science.gov (United States)

    Friebe, Sebastian; Mundstock, Alexander; Schneider, Daniel; Caro, Jürgen

    2017-05-11

    The preparation and scalability of zeolite or metal organic framework (MOF) membranes remains a major challenge, and thus prevents the application of these materials in large-scale gas separation. Additionally, several zeolite or MOF materials are quite difficult or nearly impossible to grow as defect-free layers, and require expensive macroporous ceramic or polymer supports. Here, we present new self-supporting zeolite and MOF composite membranes, called Polymer-Stabilized Percolation Membranes (PSPMs), consisting of a pressed gas selective percolation network (in our case ZIF-8, NaX and MIL-140) and a gas-impermeable infiltrated epoxy resin for cohesion. We demonstrate the performance of these PSPMs by separating binary mixtures of H 2 /CO 2 and H 2 /CH 4 . We report the brickwork-like architecture featuring selective percolation pathways and the polymer as a stabilizer, compare the mechanical stability of said membranes with competing materials, and give an outlook on how economic these membranes may become. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  14. A New Pseudoinverse Matrix Method For Balancing Chemical Equations And Their Stability

    International Nuclear Information System (INIS)

    Risteski, Ice B.

    2008-01-01

    In this work is given a new pseudoniverse matrix method for balancing chemical equations. Here offered method is founded on virtue of the solution of a Diophantine matrix equation by using of a Moore-Penrose pseudoinverse matrix. The method has been tested on several typical chemical equations and found to be very successful for the all equations in our extensive balancing research. This method, which works successfully without any limitations, also has the capability to determine the feasibility of a new chemical reaction, and if it is feasible, then it will balance the equation. Chemical equations treated here possess atoms with fractional oxidation numbers. Also, in the present work are introduced necessary and sufficient criteria for stability of chemical equations over stability of their extended matrices

  15. Chemical stability of insulin. 3. Influence of excipients, formulation, and pH.

    Science.gov (United States)

    Brange, J; Langkjaer, L

    1992-01-01

    The influence of auxiliary substances and pH on the chemical transformations of insulin in pharmaceutical formulation, including various hydrolytic and intermolecular cross-linking reactions, was studied. Bacteriostatic agents had a profound stabilizing effect--phenol > m-cresol > methylparaben--on deamidation as well as on insulin intermolecular cross-linking reactions. Of the isotonicity substances, NaCl generally had a stabilizing effect whereas glycerol and glucose led to increased chemical deterioration. Phenol and sodium chloride exerted their stabilizing effect through independent mechanisms. Zinc ions, in concentrations that promote association of insulin into hexamers, increase the stability, whereas higher zinc content had no further influence. Protamine gave rise to additional formation of covalent protamine-insulin products which increased with increasing protamine concentration. The impact of excipients on the chemical processes seems to be dictated mainly via an influence on the three-dimensional insulin structure. The effect of the physical state of the insulin on the chemical stability was also complex, suggesting an intricate dependence of intermolecular proximity of involved functional groups. At pH values below five and above eight, insulin degrades relatively fast. At acid pH, deamidation at residue A21 and covalent insulin dimerization dominates, whereas disulfide reactions leading to covalent polymerization and formation of A- and B-chains prevailed in alkaline medium. Structure-reactivity relationship is proposed to be a main determinant for the chemical transformation of insulin.

  16. Importance of asparagine on the conformational stability and chemical reactivity of selected anti-inflammatory peptides

    Energy Technology Data Exchange (ETDEWEB)

    Soriano-Correa, Catalina, E-mail: csorico@comunidad.unam.mx [Química Computacional, Facultad de Estudios Superiores (FES)-Zaragoza, Universidad Nacional Autónoma de México (UNAM), Iztapalapa, C.P. 09230 México, D.F. (Mexico); Barrientos-Salcedo, Carolina [Laboratorio de Química Médica y Quimiogenómica, Facultad de Bioanálisis Campus Veracruz-Boca del Río, Universidad Veracruzana, C.P. 91700 Veracruz (Mexico); Campos-Fernández, Linda; Alvarado-Salazar, Andres [Química Computacional, Facultad de Estudios Superiores (FES)-Zaragoza, Universidad Nacional Autónoma de México (UNAM), Iztapalapa, C.P. 09230 México, D.F. (Mexico); Esquivel, Rodolfo O. [Departamento de Química, Universidad Autónoma Metropolitana-Iztapalapa (UAM-Iztapalapa), C.P. 09340 México, D.F. (Mexico)

    2015-08-18

    Highlights: • Asparagine plays an important role to anti-inflammatory effect of peptides. • The electron-donor substituent groups favor the formation of the hydrogen bonds, which contribute in the structural stability of peptides. • Chemical reactivity and the physicochemical features are crucial in the biological functions of peptides. - Abstract: Inflammatory response events are initiated by a complex series of molecular reactions that generate chemical intermediaries. The structure and properties of peptides and proteins are determined by the charge distribution of their side chains, which play an essential role in its electronic structure and physicochemical properties, hence on its biological functionality. The aim of this study was to analyze the effect of changing one central amino acid, such as substituting asparagine for aspartic acid, from Cys–Asn–Ser in aqueous solution, by assessing the conformational stability, physicochemical properties, chemical reactivity and their relationship with anti-inflammatory activity; employing quantum-chemical descriptors at the M06-2X/6-311+G(d,p) level. Our results suggest that asparagine plays a more critical role than aspartic acid in the structural stability, physicochemical features, and chemical reactivity of these tripeptides. Substituent groups in the side chain cause significant changes on the conformational stability and chemical reactivity, and consequently on their anti-inflammatory activity.

  17. Influence of some DNA-alkylating drugs on thermal stability, acid and osmotic resistance of the membrane of whole human erythrocytes and their ghosts.

    Science.gov (United States)

    Ivanov, I T; Gadjeva, V

    2000-09-01

    Human erythrocytes and their resealed ghosts were alkylated under identical conditions using three groups of alkylating antitumor agents: mustards, triazenes and chloroethyl nitrosoureas. Osmotic fragility, acid resistance and thermal stability of membranes were changed only in alkylated ghosts in proportion to the concentration of the alkylating agent. All the alkylating agents decreased acid resistance in ghosts. The clinically used drugs sarcolysine, dacarbazine and lomustine all decreased osmotic fragility and thermal stability of ghost membranes depending on their lipophilicity. DM-COOH did not decrease osmotic fragility and thermal stability of ghost membranes, while NEM increased thermal stability of membranes. The preliminary but not subsequent treatment of ghosts with DM-COOH fully abolished the alkylation-induced thermal labilization of ghost membrane proteins while NEM had a partial effect only. The present study gives direct evidence that alkylating agents, having a high therapeutic activity against malignant growth, bind covalently to proteins of cellular membranes.

  18. Hypothesis for prediction of environmental stability of chemicals by mass spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Tremolada, P; Di Guardo, A; Calamari, D; Davoli, E; Fanelli, R [Milan Univ. (Italy). Ist. di Entomologia Agraria Istituto di Ricerche Farmacologiche Mario Negri, Milan (Italy)

    1992-01-01

    The environmental persistence of organic chemicals is generally very hard to predict. In this work, the hypothesis of the use of fragmentation data in Mass Spectrometry (MS) as a possible 'stability index' of the molecules is presented. Since the fragmentation is determined by the thermodynamic properties of the molecules, it is possible to deduct information about the 'intrinsic stability' of a chemical. Such information can be used and correlated to predict the environmental degradability of a substance, especially referring to abiotic degradation. To study this relation, three different methods of measuring the fragmentation patterns are compared. All the methods show similar behaviour and one of them, in particular, shows a very good qualitative correlation between fragmentation data and persistence values found in literature. A possible 'stability index' for the quantitative prediction of the environmental degradation of a chemical is discussed.

  19. Potentiometric sensing of iodide using polymeric membranes of microwave stabilized β-AgI

    International Nuclear Information System (INIS)

    James, Dhanya; Rao, T. Prasada

    2012-01-01

    Highlights: ► Stable β-phase was obtained by post MW irradiation of AgI precipitate. ► Constructed ISEby dispersing stable β-AgI crystals in polyvinyl chloride. ► Designed iodide ISE exhibited wide linear range and fast response. ► Highly selective with selectivity factors less than 10 −6 . ► Successfully applied to natural waters, table salt and human urine samples. - Abstract: A polymer based heterogeneous ion selective electrode (ISE) membrane was fabricated for the potentiometric sensing of iodide. The sensing element used for the preparation of the ISE membrane was microwave stabilized β-AgI. Because microwave energy was found to be beneficial for causing hysteresis at the phase transition temperature of AgI, an attempt has been made to prepare stable and conductive β-AgI crystals by post microwave irradiation under high pressure. A conventionally precipitated AgI based ISE was also fabricated for comparative studies. The β-AgI based ISE could respond to a wide range of iodide concentrations (1 × 10 −8 to 1 M) within 60 s with a detection limit of 10 nM. The ISE gave stable response to iodide ions in a pH range of 2.0–8.0 and was highly selective in the presence of various interfering ions. The performance of the proposed iodide ISE in the analysis of natural and seawater samples was encouraging, and the determination of iodide in table salt and human urine samples was explained using the developed sensor.

  20. Cell membrane thermo-stability studies through joint segregation analysis in various wheat populations

    International Nuclear Information System (INIS)

    Ullah, K.; Khan, N.U.; Gul, S.; Khan, S.J.

    2014-01-01

    Using joint segregation analysis (JSA) technique as statistical approach, mixed inheritance analysis for cell plasma membrane as membrane thermal stability (MTS) was assayed in two parental lines (P1, P2) and their four populations (F1, BC1, BC2, F2) of four wheat crosses, viz., Hashim-08 * LU-26, Farid-06 * Shafaq, Parula * Blue Silver and TD-1 * D-97603 at Faculty of Agriculture, Gomal University, Dera Ismail Khan, Pakistan during crop season 2011-12. Results revealed that MTS was under control of two mixed groups of genes i.e., additive-dominant-epistatic major genes plus additive-dominant-epistasis of polygenes (model E) in Hashim-08 * LU-26 and Farid-06 * Shafaq crosses, respectively. In cross Parula * Blue Silver, it was governed by mixed genes i.e. one major-gene and additive-dominance-epistatic polygenes (model D). However, in cross TD-1 * D-97603, the MTS was under the influence of mixed epistasis of two major genes plus polygenes (model E-1). Polygene variation and polygene heritability were higher than major gene variation and heritability in crosses Hashim-08 * LU-26 and Farid-06 * Shafaq. In crosses Parula * Blue Silver and TD-1 * D-97603, the major gene variation and heritability were higher than polygene variation and heritability, indicating maximum contribution of the major genes. While in cross TD-1 * D-97603, epistatic components were also positive and due to which the polygene heritability was almost zero. Moderate to high environmental variation in the MTS for segregating generations revealed that the said trait was highly persuaded by the environment. However, the genetic behavior of the MTS suggested that early selection for MTS in the crosses Hashim-08 * LU-26 and Farid-06 * Shafaq would be efficient. Whereas, the delayed selection in crosses Parula * Blue Silver and TD-1 * D-97603 until the accumulation of maximum favorable genes will be effective. (author)

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

    Science.gov (United States)

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

    2017-10-15

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

  2. Osmotic versus conventional membrane bioreactors integrated with reverse osmosis for water reuse: Biological stability, membrane fouling, and contaminant removal.

    Science.gov (United States)

    Luo, Wenhai; Phan, Hop V; Xie, Ming; Hai, Faisal I; Price, William E; Elimelech, Menachem; Nghiem, Long D

    2017-02-01

    This study systematically compares the performance of osmotic membrane bioreactor - reverse osmosis (OMBR-RO) and conventional membrane bioreactor - reverse osmosis (MBR-RO) for advanced wastewater treatment and water reuse. Both systems achieved effective removal of bulk organic matter and nutrients, and almost complete removal of all 31 trace organic contaminants investigated. They both could produce high quality water suitable for recycling applications. During OMBR-RO operation, salinity build-up in the bioreactor reduced the water flux and negatively impacted the system biological treatment by altering biomass characteristics and microbial community structure. In addition, the elevated salinity also increased soluble microbial products and extracellular polymeric substances in the mixed liquor, which induced fouling of the forward osmosis (FO) membrane. Nevertheless, microbial analysis indicated that salinity stress resulted in the development of halotolerant bacteria, consequently sustaining biodegradation in the OMBR system. By contrast, biological performance was relatively stable throughout conventional MBR-RO operation. Compared to conventional MBR-RO, the FO process effectively prevented foulants from permeating into the draw solution, thereby significantly reducing fouling of the downstream RO membrane in OMBR-RO operation. Accumulation of organic matter, including humic- and protein-like substances, as well as inorganic salts in the MBR effluent resulted in severe RO membrane fouling in conventional MBR-RO operation. Crown Copyright © 2016. Published by Elsevier Ltd. All rights reserved.

  3. Stability of racemic and chiral steady states in open and closed chemical systems

    Energy Technology Data Exchange (ETDEWEB)

    Ribo, Josep M. [Departament de Quimica Organica, Universitat de Barcelona, c. Marti i Franques 1, Barcelona (Spain); Hochberg, David [Centro de Astrobiologia (CSIC-INTA), Ctra. Ajalvir Km. 4, 28850 Torrejon de Ardoz, Madrid (Spain)], E-mail: hochbergd@inta.es

    2008-12-22

    The stability properties of models of spontaneous mirror symmetry breaking in chemistry are characterized algebraically. The models considered here all derive either from the Frank model or from autocatalysis with limited enantioselectivity. Emphasis is given to identifying the critical parameter controlling the chiral symmetry breaking transition from racemic to chiral steady-state solutions. This parameter is identified in each case, and the constraints on the chemical rate constants determined from dynamic stability are derived.

  4. Stability of racemic and chiral steady states in open and closed chemical systems

    International Nuclear Information System (INIS)

    Ribo, Josep M.; Hochberg, David

    2008-01-01

    The stability properties of models of spontaneous mirror symmetry breaking in chemistry are characterized algebraically. The models considered here all derive either from the Frank model or from autocatalysis with limited enantioselectivity. Emphasis is given to identifying the critical parameter controlling the chiral symmetry breaking transition from racemic to chiral steady-state solutions. This parameter is identified in each case, and the constraints on the chemical rate constants determined from dynamic stability are derived

  5. Using proven, cost-effective chemical stabilization to remediate radioactive and heavy metal contaminated sites

    International Nuclear Information System (INIS)

    Jensen, R.; Sogue, A.

    1999-01-01

    Rocky Mountain Remediation Services, L.L.C. (RMRS) has deployed a cost-effective metals stabilization method which can be used to reduce the cost of remediation projects where radioactivity and heavy metals are the contaminants of concern. The Envirobond TM process employs the use of a proprietary chemical process to stabilize metals in many waste forms, and provides an excellent binding system that can easily be compacted to reduce the waste into a shippable brick called Envirobric TM . The advantages of using chemical stabilization are: (1) Low cost, due to the simplicity of the process design and inexpensive reagents. (2) Chemical stabilization is easily deployed in field applications, which limit the amount of shielding and other protective measures. (3) The process does not add volume and bulk to the treated waste; after treatment the materials may be able to remain on-site, or if transportation and disposal is required the cost will be reduced due to lower volumes. (4) No secondary waste. The simplicity of this process creates a safe environment while treating the residues, and the long-term effectiveness of this type of chemical stabilization lowers the risk of future release of hazardous elements associated with the residues. (author)

  6. Impact of operation conditions, foulant adsorption, and chemical cleaning on the nanomechanical properties of ultrafiltraion hollow fiber membranes

    KAUST Repository

    Gutierrez, Leonardo

    2018-04-06

    This study analyzed the change in nanomechanical properties of ultrafiltration hollow fiber membranes harvested from pilot-scale units after twelve months of operation. Quantitative Nanomechanical Mapping technique was used to distinguish between adhesion, dissipation, deformation, and modulus while simultaneously generating a topographic image of membranes. Nanomechanical maps of virgin membranes evidenced surfaces of heterogeneous properties and were described by probability density functions. Operating conditions and feed quality exerted an impact on membranes. Clean harvested membranes showed a higher mean modulus and dissipation, and a lower deformation than virgin membranes, indicating stiffer membranes of lower elastic deformation. A significant fraction of these measurements displayed peak values deviating from the distribution; which represents regions of the membrane with properties highly differing from the probability density function. The membrane polymeric material experienced severe physicochemical changes by foulant adsorption and reaction with cleaning agents. Foulant adsorption on membranes was heterogeneous in both morphology and mechanical properties and could not be statistically described. Foulants, i.e., mainly consisting of polysaccharides and proteinaceous structures, displayed low elastic deformation and high roughness and adhesion. The presence of foulants after chemical cleaning and their high adhesion would be a direct nanoscale evidence of irreversible fouling. By the end of the operation, the Trans-Membrane Pressure experienced a 40% increase. The cleaning process was not able to fully recover the initial TMP, indicating irreversible fouling, i.e., permanent change in membrane characteristics and decrease in performance. These results suggest a link between the macroscopic properties and nanomechanical characteristics of membranes. This study advances our nanoscale understanding of the impact of fouling and operating conditions on

  7. Effects of chemical sludge disintegration on the performances of wastewater treatment by membrane bioreactor.

    Science.gov (United States)

    Oh, Young-Khee; Lee, Ki-Ryong; Ko, Kwang-Baik; Yeom, Ick-Tae

    2007-06-01

    A new wastewater treatment process combining a membrane bioreactor (MBR) with chemical sludge disintegration was tested in bench scale experiments. In particular, the effects of the disintegration treatment on the excess sludge production in MBR were investigated. Two MBRs were operated. In one reactor, a part of the mixed liquor was treated with NaOH and ozone gas consecutively and was returned to the bioreactor. The flow rate of the sludge disintegration stream was 1.5% of the influent flow rate. During the 200 days of operation, the MLSS level in the bioreactor with the disintegration treatment was maintained relatively constant at the range of 10,000-11,000 mg/L while it increased steadily up to 25,000 mg/L in the absence of the treatment. In the MBR with the sludge disintegration, relatively constant transmembrane pressures (TMPs) could be maintained for more than 6 months while the MBR without disintegration showed an abrupt increase of TMP in the later phase of the operation. In conclusion, a complete control of excess sludge production in the membrane-coupled bioreactor was possible without significant deterioration of the treated water quality and membrane performances.

  8. A robust method to screen detergents for membrane protein stabilization, revisited.

    Science.gov (United States)

    Champeil, Philippe; Orlowski, Stéphane; Babin, Simon; Lund, Sten; le Maire, Marc; Møller, Jesper; Lenoir, Guillaume; Montigny, Cédric

    2016-10-15

    This report is a follow up of our previous paper (Lund, Orlowski, de Foresta, Champeil, le Maire and Møller (1989), J Biol Chem 264:4907-4915) showing that solubilization in detergent of a membrane protein may interfere with its long-term stability, and proposing a protocol to reveal the kinetics of such irreversible inactivation. We here clarify the fact that when various detergents are tested for their effects, special attention has of course to be paid to their critical micelle concentration. We also investigate the effects of a few more detergents, some of which have been recently advertised in the literature, and emphasize the role of lipids together with detergents. Among these detergents, lauryl maltose neopentyl glycol (LMNG) exerts a remarkable ability, even higher than that of β-dodecylmaltoside (DDM), to protect our test enzyme, the paradigmatic P-type ATPase SERCA1a from sarcoplasmic reticulum. Performing such experiments for one's favourite protein probably remains useful in pre-screening assays testing various detergents. Copyright © 2016 Elsevier Inc. All rights reserved.

  9. Membrane Protein Stability Analyses by Means of Protein Energy Profiles in Case of Nephrogenic Diabetes Insipidus

    Directory of Open Access Journals (Sweden)

    Florian Heinke

    2012-01-01

    Full Text Available Diabetes insipidus (DI is a rare endocrine, inheritable disorder with low incidences in an estimated one per 25,000–30,000 live births. This disease is characterized by polyuria and compensatory polydypsia. The diverse underlying causes of DI can be central defects, in which no functional arginine vasopressin (AVP is released from the pituitary or can be a result of defects in the kidney (nephrogenic DI, NDI. NDI is a disorder in which patients are unable to concentrate their urine despite the presence of AVP. This antidiuretic hormone regulates the process of water reabsorption from the prourine that is formed in the kidney. It binds to its type-2 receptor (V2R in the kidney induces a cAMP-driven cascade, which leads to the insertion of aquaporin-2 water channels into the apical membrane. Mutations in the genes of V2R and aquaporin-2 often lead to NDI. We investigated a structure model of V2R in its bound and unbound state regarding protein stability using a novel protein energy profile approach. Furthermore, these techniques were applied to the wild-type and selected mutations of aquaporin-2. We show that our results correspond well to experimental water ux analysis, which confirms the applicability of our theoretical approach to equivalent problems.

  10. Stability of eosin-5'-maleimide dye used in flow cytometric analysis for red cell membrane disorders.

    Science.gov (United States)

    Mehra, Simmi; Tyagi, Neetu; Dorwal, Pranav; Pande, Amit; Jain, Dharmendra; Sachdev, Ritesh; Raina, Vimarsh

    2015-06-01

    The eosin-5'-maleimide (EMA) binding test using flow cytometry is a common method to measure reduced mean channel fluorescence (MCF) of EMA-labeled red blood cells (RBCs) from patients with red cell membrane disorders. The basic principle of the EMA-RBC binding test involves the covalent binding of EMA to lysine-430 on the first extracellular loop of band 3 protein. In the present study, the MCF of EMA was analyzed for samples derived from 12 healthy volunteers (controls) to determine the stability (i.e., the percentage decrease in fluorescence) of EMA over a period of 1 year. Comparison of periodical MCF readings over time, that is, at 2-month intervals, showed that there were no significant changes in mean channel fluorescence for up to 6 months; however, there was a significant decrease in MCF at 8 months. For optimal dye utilization, EMA remained stable only for up to 6 months. Therefore, we recommend reconstitution of the dye every 6 months when implementing this test and storage at -80℃ in dark conditions.

  11. SiO2 stabilized Pt/C cathode catalyst for proton exchange membrane fuel cells

    International Nuclear Information System (INIS)

    Zhu Tong; Du Chunyu; Liu Chuntao; Yin Geping; Shi Pengfei

    2011-01-01

    This paper describes the preparation of SiO 2 stabilized Pt/C catalyst (SiO 2 /Pt/C) by the hydrolysis of alkoxysilane, and examines the possibility that the SiO 2 /Pt/C is used as a durable cathode catalyst for proton exchange membrane fuel cells (PEMFCs). TEM and XRD results revealed that the hydrolysis of alkoxysilane did not significantly change the morphology and crystalline structure of Pt particles. The SiO 2 /Pt/C catalyst exhibited higher durability than the Pt/C one, due to the facts that the silica layers covered were beneficial for reducing the Pt aggregation and dissolution as well as increasing the corrosion resistance of supports, although the benefit of silica covering was lower than the case of Pt/CNT catalyst. Also, it was observed that the activity of the SiO 2 /Pt/C catalyst for the oxygen reduction reaction was somewhat reduced compared to the Pt/C one after the silica covering. This reduction was partially due to the low oxygen kinetics as revealed by the rotating-disk-electrode measurement. Silica covering by hydrolysis of only 3-aminopropyl trimethoxysilane is able to achieve a good balance between the durability and activity, leading to SiO 2 /Pt/C as a promising cathode catalyst for PEMFCs.

  12. Effects of physical and chemical aspects on membrane fouling and cleaning using interfacial free energy analysis in forward osmosis.

    Science.gov (United States)

    Zhang, Wanzhu; Dong, Bingzhi

    2018-05-20

    Natural organic matter (NOM) in micro-polluted water purification using membranes is a critical issue to handle. Understanding the fouling mechanism in the forward osmosis (FO) process, particularly identifying the predominant factor that controls membrane fouling, could have significant effects on exerting the advantages of FO technique. Cellulose triacetate no-woven (CTA-NW) membrane is applied to experiments with a high removal efficiency (> 99%) for the model foulant. Tannic acid (TA) is used as a surrogate foulant for NOM in the membrane fouling process, thus enabling the analysis of the effects of physical and chemical aspects of water flux, retention, and adsorption. The membrane fouling behavior is affected mainly by the combined effects of the osmotic dragging force and the interaction of the pH in the working solution, foulants, and calcium ions, as demonstrated by the water flux loss and the changes of membrane retention and adsorption. The fouled CTA-NW membrane (in PRO mode) could be flux-recovered by > 85% through physical cleaning methods. The interfacial free energy analysis theory was used to analyze the membrane fouling behavior with calculating the interfacial cohesion and adhesion free energies. The cohesion free energy refers to the deposition of foulants (TA or TA combined with calcium ions) on a fouled membrane. In addition, the adhesion free energy could be used to evaluate the interaction between foulants and a clean membrane.

  13. Innovative methods to stabilize liquid membranes for removal of radionuclides from groundwater

    Energy Technology Data Exchange (ETDEWEB)

    Lokhandwala, K. [Membrane Technology and Research, Inc., Menlo Park, CA (United States)

    1997-10-01

    In this Phase I Small Business Innovation Research program, Membrane Technology Research, Inc., is developing a stable liquid membrane for extracting uranium and other radionuclides from groundwater. The improved membrane can also be applied to separation of other metal ions from aqueous streams in industrial operations.

  14. Chemical crosslinking and mass spectrometry studies of the structure and dynamics of membrane proteins and receptors.

    Energy Technology Data Exchange (ETDEWEB)

    Haskins, William E.; Leavell, Michael D.; Lane, Pamela; Jacobsen, Richard B.; Hong, Joohee; Ayson, Marites J.; Wood, Nichole L.; Schoeniger, Joseph S.; Kruppa, Gary Hermann; Sale, Kenneth L.; Young, Malin M.; Novak, Petr

    2005-03-01

    Membrane proteins make up a diverse and important subset of proteins for which structural information is limited. In this study, chemical cross-linking and mass spectrometry were used to explore the structure of the G-protein-coupled photoreceptor bovine rhodopsin in the dark-state conformation. All experiments were performed in rod outer segment membranes using amino acid 'handles' in the native protein sequence and thus minimizing perturbations to the native protein structure. Cysteine and lysine residues were covalently cross-linked using commercially available reagents with a range of linker arm lengths. Following chemical digestion of cross-linked protein, cross-linked peptides were identified by accurate mass measurement using liquid chromatography-fourier transform mass spectrometry and an automated data analysis pipeline. Assignments were confirmed and, if necessary, resolved, by tandem MS. The relative reactivity of lysine residues participating in cross-links was evaluated by labeling with NHS-esters. A distinct pattern of cross-link formation within the C-terminal domain, and between loop I and the C-terminal domain, emerged. Theoretical distances based on cross-linking were compared to inter-atomic distances determined from the energy-minimized X-ray crystal structure and Monte Carlo conformational search procedures. In general, the observed cross-links can be explained by re-positioning participating side-chains without significantly altering backbone structure. One exception, between C3 16 and K325, requires backbone motion to bring the reactive atoms into sufficient proximity for cross-linking. Evidence from other studies suggests that residues around K325 for a region of high backbone mobility. These findings show that cross-linking studies can provide insight into the structural dynamics of membrane proteins in their native environment.

  15. Integrated Microfluidic Membrane Transistor Utilizing Chemical Information for On-Chip Flow Control

    Science.gov (United States)

    Frank, Philipp; Schreiter, Joerg; Haefner, Sebastian; Paschew, Georgi; Voigt, Andreas; Richter, Andreas

    2016-01-01

    Microfluidics is a great enabling technology for biology, biotechnology, chemistry and general life sciences. Despite many promising predictions of its progress, microfluidics has not reached its full potential yet. To unleash this potential, we propose the use of intrinsically active hydrogels, which work as sensors and actuators at the same time, in microfluidic channel networks. These materials transfer a chemical input signal such as a substance concentration into a mechanical output. This way chemical information is processed and analyzed on the spot without the need for an external control unit. Inspired by the development electronics, our approach focuses on the development of single transistor-like components, which have the potential to be used in an integrated circuit technology. Here, we present membrane isolated chemical volume phase transition transistor (MIS-CVPT). The device is characterized in terms of the flow rate from source to drain, depending on the chemical concentration in the control channel, the source-drain pressure drop and the operating temperature. PMID:27571209

  16. Integrated Microfluidic Membrane Transistor Utilizing Chemical Information for On-Chip Flow Control.

    Science.gov (United States)

    Frank, Philipp; Schreiter, Joerg; Haefner, Sebastian; Paschew, Georgi; Voigt, Andreas; Richter, Andreas

    2016-01-01

    Microfluidics is a great enabling technology for biology, biotechnology, chemistry and general life sciences. Despite many promising predictions of its progress, microfluidics has not reached its full potential yet. To unleash this potential, we propose the use of intrinsically active hydrogels, which work as sensors and actuators at the same time, in microfluidic channel networks. These materials transfer a chemical input signal such as a substance concentration into a mechanical output. This way chemical information is processed and analyzed on the spot without the need for an external control unit. Inspired by the development electronics, our approach focuses on the development of single transistor-like components, which have the potential to be used in an integrated circuit technology. Here, we present membrane isolated chemical volume phase transition transistor (MIS-CVPT). The device is characterized in terms of the flow rate from source to drain, depending on the chemical concentration in the control channel, the source-drain pressure drop and the operating temperature.

  17. Uptake rate constants and partition coefficients for vapor phase organic chemicals using semipermeable membrane devices (SPMDs)

    Science.gov (United States)

    Cranor, W.L.; Alvarez, D.A.; Huckins, J.N.; Petty, J.D.

    2009-01-01

    To fully utilize semipermeable membrane devices (SPMDs) as passive samplers in air monitoring, data are required to accurately estimate airborne concentrations of environmental contaminants. Limited uptake rate constants (kua) and no SPMD air partitioning coefficient (Ksa) existed for vapor-phase contaminants. This research was conducted to expand the existing body of kinetic data for SPMD air sampling by determining kua and Ksa for a number of airborne contaminants including the chemical classes: polycyclic aromatic hydrocarbons, organochlorine pesticides, brominated diphenyl ethers, phthalate esters, synthetic pyrethroids, and organophosphate/organosulfur pesticides. The kuas were obtained for 48 of 50 chemicals investigated and ranged from 0.03 to 3.07??m3??g-1??d-1. In cases where uptake was approaching equilibrium, Ksas were approximated. Ksa values (no units) were determined or estimated for 48 of the chemicals investigated and ranging from 3.84E+5 to 7.34E+7. This research utilized a test system (United States Patent 6,877,724 B1) which afforded the capability to generate and maintain constant concentrations of vapor-phase chemical mixtures. The test system and experimental design employed gave reproducible results during experimental runs spanning more than two years. This reproducibility was shown by obtaining mean kua values (n??=??3) of anthracene and p,p???-DDE at 0.96 and 1.57??m3??g-1??d-1 with relative standard deviations of 8.4% and 8.6% respectively.

  18. Thermodynamic stability of elementary chemical reactions proceeding at finite rates revisited using Lyapunov function analysis

    International Nuclear Information System (INIS)

    Burande, Chandrakant S.; Bhalekar, Anil A.

    2005-01-01

    The thermodynamic stability of a few representative elementary chemical reactions proceeding at finite rates has been investigated using the recently proposed thermodynamic Lyapunov function and following the steps of Lyapunov's second method (also termed as the direct method) of stability of motion. The thermodynamic Lyapunov function; L s , used herein is the excess rate of entropy production in the thermodynamic perturbation space, which thereby inherits the dictates of the second law of thermodynamics. This Lyapunov function is not the same as the excess entropy rate that one encounters in thermodynamic (irreversible) literature. The model chemical conversions studied in this presentation are A+B→v x X and A+B↔ν x X. For the sake of simplicity, the thermal effects of chemical reactions have been considered as not adding to the perturbation as our main aim was to demonstrate how one should use systematically the proposed thermodynamic Lyapunov function following the steps of Lyapunov's second method of stability of motion. The domains of thermodynamic stability under the constantly acting small disturbances, thermodynamic asymptotic stability and thermodynamic instability in these model systems get established

  19. New class of thermosetting plastics has improved strength, thermal and chemical stability

    Science.gov (United States)

    Burns, E. A.; Dubrow, B.; Lubowitz, H. R.

    1967-01-01

    New class of thermosetting plastics has high hydrocarbon content, high stiffness, thermal stability, humidity resistance, and workability in the precured state. It is designated cyclized polydiene urethane, and is applicable as matrices to prepare chemically stable ablative materials for rocket nose cones of nozzles.

  20. Design and construction control guidance for chemically stabilized pavement base layers.

    Science.gov (United States)

    2013-12-01

    A laboratory and field study was conducted related to chemically stabilized pavement layers, which is also : referred to as soil-cement. Soil-cement practices within MDOT related to Class 9C soils used for base layers : were evaluated in this report....

  1. Leaching behavior and chemical stability of copper butyl xanthate complex under acidic conditions.

    Science.gov (United States)

    Chang, Yi Kuo; Chang, Juu En; Chiang, Li Choung

    2003-08-01

    Although xanthate addition can be used for treating copper-containing wastewater, a better understanding of the leaching toxicity and the stability characteristics of the copper xanthate complexes formed is essential. This work was undertaken to evaluate the leaching behavior of copper xanthate complex precipitates by means of toxicity characteristics leaching procedure (TCLP) and semi-dynamic leaching test (SDLT) using 1 N acetic acid solution as the leachant. Also, the chemical stability of the copper xanthate complex during extraction has been examined with the studying of variation of chemical structure using UV-vis, Fourier transform infrared and X-ray photoelectron spectroscopies (XPS). Both TCLP and SDLT results showed that a negligible amount of copper ion was leached out from the copper xanthate complex precipitate, indicating that the complex exhibited a high degree of copper leaching stability under acidic conditions. Nevertheless, chemical structure of the copper xanthate complex precipitate varied during the leaching tests. XPS data suggested that the copper xanthate complex initially contained both cupric and cuprous xanthate, but the unstable cupric xanthate change to the cuprous form after acid extraction, indicating the cuprous xanthate to be the final stabilizing structure. Despite that, the changes of chemical structure did not induce the rapid leaching of copper from the copper xanthate complex.

  2. Evaluation of the effects of enzyme-based liquid chemical stabilizers on subgrade soils

    CSIR Research Space (South Africa)

    Mgangira, Martin B

    2009-07-01

    Full Text Available The purpose of this study was to asses the strength of enzyme treated soil material. Thus the aim of the paper is to present laboratory results on the effects of two enzyme-based liquid chemicals as soil stabilizers. Soil samples were prepared...

  3. Fast Pyrolysis Oil Stabilization: An Integrated Catalytic and Membrane Approach for Improved Bio-oils. Final Report

    Energy Technology Data Exchange (ETDEWEB)

    Huber, George W.; Upadhye, Aniruddha A.; Ford, David M.; Bhatia, Surita R.; Badger, Phillip C.

    2012-10-19

    This University of Massachusetts, Amherst project, "Fast Pyrolysis Oil Stabilization: An Integrated Catalytic and Membrane Approach for Improved Bio-oils" started on 1st February 2009 and finished on August 31st 2011. The project consisted following tasks: Task 1.0: Char Removal by Membrane Separation Technology The presence of char particles in the bio-oil causes problems in storage and end-use. Currently there is no well-established technology to remove char particles less than 10 micron in size. This study focused on the application of a liquid-phase microfiltration process to remove char particles from bio-oil down to slightly sub-micron levels. Tubular ceramic membranes of nominal pore sizes 0.5 and 0.8m were employed to carry out the microfiltration, which was conducted in the cross-flow mode at temperatures ranging from 38 to 45 C and at three different trans-membrane pressures varying from 1 to 3 bars. The results demonstrated the removal of the major quantity of char particles with a significant reduction in overall ash content of the bio-oil. The results clearly showed that the cake formation mechanism of fouling is predominant in this process. Task 2.0 Acid Removal by Membrane Separation Technology The feasibility of removing small organic acids from the aqueous fraction of fast pyrolysis bio-oils using nanofiltration (NF) and reverse osmosis (RO) membranes was studied. Experiments were carried out with a single solute solutions of acetic acid and glucose, binary solute solutions containing both acetic acid and glucose, and a model aqueous fraction of bio-oil (AFBO). Retention factors above 90% for glucose and below 0% for acetic acid were observed at feed pressures near 40 bar for single and binary solutions, so that their separation in the model AFBO was expected to be feasible. However, all of the membranes were irreversibly damaged when experiments were conducted with the model AFBO due to the presence of guaiacol in the feed solution. Experiments

  4. The development of orally administrable gemcitabine prodrugs with D-enantiomer amino acids: enhanced membrane permeability and enzymatic stability.

    Science.gov (United States)

    Tsume, Yasuhiro; Incecayir, Tuba; Song, Xueqin; Hilfinger, John M; Amidon, Gordon L

    2014-04-01

    Gemcitabine prodrugs with D- and L-configuration amino acids were synthesized and their chemical stability in buffers, resistance to glycosidic bond metabolism, enzymatic activation, permeability in Caco-2 cells and mouse intestinal membrane, anti-proliferation activity in cancer cell were determined and compared to that of parent drug, gemcitabine. Prodrugs containing D-configuration amino acids were enzymatically more stable than ones with L-configuration amino acids. The activation of all gemcitabine prodrugs was 1.3-17.6-fold faster in cancer cell homogenate than their hydrolysis in buffer, suggesting enzymatic action. The enzymatic activation of amino acid monoester prodrugs containing D-configuration amino acids in cell homogenates was 2.2-10.9-fold slower than one of amino acid monoester prodrugs with L-configuration amino acids. All prodrugs exhibited enhanced resistance to glycosidic bond metabolism by thymidine phosphorylase compared to parent gemcitabine. Gemcitabine prodrugs showed superior the effective permeability in mouse jejunum to gemcitabine. More importantly, the high plasma concentration of d-amino acid gemcitabine prodrugs was observed more than one of L-amino acid gemcitabine prodrugs. In general, the 5'-mono-amino acid monoester gemcitabine prodrugs exhibited higher permeability and uptake than their parent drug, gemcitabine. Cell proliferation assays in AsPC-1 pancreatic ductal cell line indicated that gemcitabine prodrugs were more potent than their parent drug, gemcitabine. The transport and enzymatic profiles of 5'-D-valyl-gemcitabine and 5'-D-phenylalanyl-gemcitabine suggest their potential for increased oral uptake and delayed enzymatic bioconversion as well as enhanced uptake and cytotoxic activity in cancer cells, would facilitate the development of oral dosage form for anti-cancer agents and, hence, improve the quality of life for the cancer patients. Copyright © 2014. Published by Elsevier B.V.

  5. Efficient first-principles prediction of solid stability: Towards chemical accuracy

    Science.gov (United States)

    Zhang, Yubo; Kitchaev, Daniil A.; Yang, Julia; Chen, Tina; Dacek, Stephen T.; Sarmiento-Pérez, Rafael A.; Marques, Maguel A. L.; Peng, Haowei; Ceder, Gerbrand; Perdew, John P.; Sun, Jianwei

    2018-03-01

    The question of material stability is of fundamental importance to any analysis of system properties in condensed matter physics and materials science. The ability to evaluate chemical stability, i.e., whether a stoichiometry will persist in some chemical environment, and structure selection, i.e. what crystal structure a stoichiometry will adopt, is critical to the prediction of materials synthesis, reactivity and properties. Here, we demonstrate that density functional theory, with the recently developed strongly constrained and appropriately normed (SCAN) functional, has advanced to a point where both facets of the stability problem can be reliably and efficiently predicted for main group compounds, while transition metal compounds are improved but remain a challenge. SCAN therefore offers a robust model for a significant portion of the periodic table, presenting an opportunity for the development of novel materials and the study of fine phase transformations even in largely unexplored systems with little to no experimental data.

  6. Vastly enhancing the chemical stability of phosphorene by employing an electric field.

    Science.gov (United States)

    Gao, Junfeng; Zhang, Gang; Zhang, Yong-Wei

    2017-03-23

    Currently, a major hurdle preventing phosphorene from various electronic applications is its rapid oxidation under ambient conditions. Thus how to enhance its chemical stability by suppressing oxidation becomes an urgent task. Here, we reveal a highly effective procedure to suppress the oxidation of phosphorene by employing a suitable van der Waals (vdW) substrate and a vertical electric field. Our first-principles study shows that the phosphorene-MoSe 2 vdW heterostructure is able to reverse the stability of physisorption and chemisorption of molecular O 2 on phosphorene. With further application of a vertical electric field of -0.6 V Å -1 , the energy barrier for oxidation is able to further increase to 0.91 eV, leading to a 10 5 times enhancement in its lifetime compared with that without using the procedure at room temperature. Our work presents a viable strategy to vastly enhance the chemical stability of phosphorene in air.

  7. Chemical and thermal stability of core-shelled magnetite nanoparticles and solid silica

    Science.gov (United States)

    Cendrowski, Krzysztof; Sikora, Pawel; Zielinska, Beata; Horszczaruk, Elzbieta; Mijowska, Ewa

    2017-06-01

    Pristine nanoparticles of magnetite were coated by solid silica shell forming core/shell structure. 20 nm thick silica coating significantly enhanced the chemical and thermal stability of the iron oxide. Chemical and thermal stability of this structure has been compared to the magnetite coated by mesoporous shell and pristine magnetite nanoparticles. It is assumed that six-membered silica rings in a solid silica shell limit the rate of oxygen diffusion during thermal treatment in air and prevent the access of HCl molecules to the core during chemical etching. Therefore, the core/shell structure with a solid shell requires a longer time to induce the oxidation of iron oxide to a higher oxidation state and, basically, even strong concentrated acid such as HCl is not able to dissolve it totally in one month. This leads to the desired performance of the material in potential applications such as catalysis and environmental protection.

  8. Evaluation of the influence of fluoroquinolone chemical structure on stability: forced degradation and in silico studies

    Directory of Open Access Journals (Sweden)

    André Valle de Bairros

    2018-05-01

    Full Text Available ABSTRACT Fluoroquinolones are a known antibacterial class commonly used around the world. These compounds present relative stability and they may show some adverse effects according their distinct chemical structures. The chemical hydrolysis of five fluoroquinolones was studied using alkaline and photolytic degradation aiming to observe the differences in molecular reactivity. DFT/B3LYP-6.31G* was used to assist with understanding the chemical structure degradation. Gemifloxacin underwent degradation in alkaline medium. Gemifloxacin and danofloxacin showed more degradation perceptual indices in comparison with ciprofloxacin, enrofloxacin and norfloxacin in photolytic conditions. Some structural features were observed which may influence degradation, such as the presence of five member rings attached to the quinolone ring and the electrostatic positive charges, showed in maps of potential electrostatic charges. These measurements may be used in the design of effective and more stable fluoroquinolones as well as the investigation of degradation products from stress stability assays.

  9. Structure and Stability of the Spinach Aquaporin SoPIP2;1 in Detergent Micelles and Lipid Membranes

    DEFF Research Database (Denmark)

    Plasencia, Ines; Survery, Sabeen; Ibragimova, Sania

    2011-01-01

    Background: SoPIP2;1 constitutes one of the major integral proteins in spinach leaf plasma membranes and belongs to the aquaporin family. SoPIP2;1 is a highly permeable and selective water channel that has been successfully overexpressed and purified with high yields. In order to optimize...... reconstitution of the purified protein into biomimetic systems, we have here for the first time characterized the structural stability of SoPIP2;1. Methodology/Principal Finding: We have characterized the protein structural stability after purification and after reconstitution into detergent micelles...... and proteoliposomes using circular dichroism and fluorescence spectroscopy techniques. The structure of SoPIP2;1 was analyzed either with the protein solubilized with octyl-beta-D-glucopyranoside (OG) or reconstituted into lipid membranes formed by E. coli lipids, diphytanoylphosphatidylcholine (DPh...

  10. Kinetic stability and membrane structure of liposomes during in vitro infant intestinal digestion: Effect of cholesterol and lactoferrin.

    Science.gov (United States)

    Liu, Weilin; Wei, Fuqiang; Ye, Aiqian; Tian, Mengmeng; Han, Jianzhong

    2017-09-01

    The effects of cholesterol and lactoferrin on the kinetic stability and membrane structural integrity of negatively charged liposomes under in vitro infant intestinal digestion conditions were elucidated using dynamic light scattering, pH-stat titration, Fourier transform infrared spectroscopy, and pyrene steady state fluorescence probes. The liposomes had a smaller particle diameter, a wider size distribution, and a greater negative charge after digestion. The incorporation of cholesterol into the phospholipid bilayers resulted in a more ordered conformation in the aliphatic tail region and reduced micropolarity, indicating that cholesterol can improve the structural stability of liposomal membranes against intestinal environmental stress. Lactoferrin coverage facilitated the release of free fatty acids and increased the microfluidity of the bilayers, reducing the structural integrity of the liposomes. This study provides useful information on the design of liposomes and other microcapsules with improved and controlled release properties during digestion for particular groups of people. Copyright © 2017 Elsevier Ltd. All rights reserved.

  11. Comparative analysis of CO2 separation from flue gas by membrane gas absorption technology and chemical absorption technology in China

    International Nuclear Information System (INIS)

    Yan, Shuiping; Fang, Mengxiang; Zhang, Weifeng; Zhong, Weilong; Luo, Zhongyang; Cen, Kefa

    2008-01-01

    This paper firstly evaluated the CO 2 absorption performance of a membrane gas absorption system (MAS) and chemical absorption system (CAS) using the overall mass transfer coefficient (K G a V ) as a basis for comparison. MAS selected microporous polypropylene (PP) hollow fiber membrane contactors to capture CO 2 from the simulated flue gas while CAS used a randomly packed column containing stainless Pall packing. Aqueous monoethanolamine (MEA) solution was adopted in both absorbers. Experimental results show that if the fresh membranes were tested, MAS has the higher K G a V values than that of CAS. However, when all the membrane pores were completely wetted or 50% pores were plugged, CAS inversely performs better than MAS in terms of K G a V values. In addition, the economic performance of MAS and CAS was also estimated. Results indicate that if the real operational time of membrane module is reduced to less than the critical value affected by the membrane price, the CO 2 captured cost of MAS is inversely higher than that of CAS. Therefore, the current well-accepted statement that MAS is superior to CAS in any case may be somewhat arbitrary unless membrane pore-wetting and pore-plugging problems, how to reduce the membrane price and how to prolong the membrane lifetime can be solved perfectly in the future. (author)

  12. The effect of peptides and ions interacting with an electrically neutral membrane interface on the structure and stability of lipid membranes in the liquid-crystalline phase and in the liquid-ordered phase

    Science.gov (United States)

    Sano, Ryoko; Masum, Shah Md; Tanaka, Tomoki; Yamashita, Yuko; Levadny, Victor; Yamazaki, Masahito

    2005-08-01

    We investigated the effects of a de novo designed peptide, WLFLLKKK (peptide-1) and La3+, which can bind with the electrically neutral lipid membrane interface, on the stability of the phosphatidylcholine (PC) membrane in the Lα phase and that of the liquid-ordered (lo) phase membranes. The results of spacing of the multilamellar vesicle and shape changes of the giant unilamellar vesicle (GUV) indicate that the peptide-1 can be partitioned into the membrane interface in the Lα phase but not into that in the lo phase. La3+ induced shape changes of GUVs of the lo phase membrane, which are the same as those of GUVs in the Lα phase. This indicates that the binding of La3+ induced an increase in the lateral compression pressure of the membrane, which decreased the surface area of the membrane in the lo phase. The difference of the membrane interface between the Lα phase and the lo phase is discussed.

  13. Understanding chemical-potential-related transient pore-pressure response to improve real-time borehole (in)stability predictions

    Energy Technology Data Exchange (ETDEWEB)

    Tare, U.A.; Mody, F.K.; Mese, A.I. [Halliburton Energy Services, Cairo (Egypt)

    2000-11-01

    Experimental studies were conducted to explain the concept of a real-time wellbore (in)stability logging methodology. The role of the chemical potential of drilling fluids on transient pore pressure and time-dependent rock property alterations of shale formations was examined by providing details about a pore pressure transmission (PPT) test. The PPT experiments exposed formation (shale) cores under simulated downhole conditions to various salt solutions and drilling fluids. The main objective was to translate the results of the PPT tests to actual drilling conditions. A 20 per cent w/w calcium chloride solution was exposed to a Pierre II shale under high pressure in the PPT apparatus. The PPT test was used to estimate the impact of a drilling fluid on shale pore pressure. The efficiency of the salt solution/shale system was also estimated. Estimates of the dynamic rock properties were made based on the obtained acoustic data. It was determined that in order to accurately model time-dependent wellbore (in)stability in the field, it is important to calibrate representative shale core response to drilling fluids under realistic in-situ conditions. The 20 per cent w/w calcium chloride solution showed very low membrane efficiency of 4.45 per cent. It was concluded that changes in the shale dynamic rock properties as a function of test fluid exposure can be obtained from the simultaneous acquisition of sonic compression and shear wave velocity data. 12 refs., 5 figs.

  14. Physico-chemical, microbiological and sensory stability of chemically preserved mango pulp

    International Nuclear Information System (INIS)

    Akhtar, S.; Riaz, M.; Nisar, A.

    2010-01-01

    The effect of sodium benzoate (SB) and potassium metabisulphite (PMS) at various concentrations on chemical, microbiological and sensory quality of mango pulp during storage was assessed. Inhibitory activity of the chemical preservatives and their effect on chemical and sensory attributes was tested periodically by simulating the industrial mango pulp storage in the lab (30-42 deg. C in the dark), for a period of 90 days. Protein, fats, decreased while ash content and total soluble solid (TSS) increased during the storage period. A slight progressive decline in pH was observed with a proportional increase (p<0.05) in the acidity of the stored pulp samples. Significant inhibition of the total bacterial count (TBC) was observed on applying the specified concentrations, however PMS was shown to be more inhibitory. Storage time significantly (p<0.05) increased the CFU/g of the pulp samples as the maximum growth was observed after 90 days of storage. Sensory characteristics of the juice prepared from treated mango pulp samples were affected negatively on addition of preservatives however, the samples were accepted by the judges even after three months of storage. (author)

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

    Science.gov (United States)

    Kwon, Jung-Hwan; Escher, Beate I

    2008-03-01

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

  16. DNA damage, acetylcholinesterase activity and lysosomal stability in native and transplanted mussels (Mytilus edulis) in areas close to coastal chemical dumping sites in Denmark

    DEFF Research Database (Denmark)

    Rank, Jette; Lehtonen, Kari K.; Strand, Jakob

    2007-01-01

    Biomarkers of genotoxicity (DNA damage, measured as tail moment in the Comet assay), neurotoxicity (acetylcholinesterase inhibition, AChE) and general stress (lysosomal membrane stability, LMS) were studied in native and transplanted blue mussels (Mytilus edulis) in coastal areas of western Denmark...... of chemical pollution complex, as seen especially in the variability in results on DNA damage, and also in regard to AChE activity. These investigations further stress the importance of understanding the effects of natural factors (salinity, temperature, water levels, rain and storm events) in correct...

  17. Physical and chemical stability of palonosetron HCl in 4 infusion solutions.

    Science.gov (United States)

    Trissel, Lawrence A; Xu, Quanyun A

    2004-10-01

    Palonosetron HCl is a selective 5-HT(3) receptor antagonist used for the prevention of chemotherapy-induced nausea and vomiting. Palonosetron HCl may be diluted in an infusion solution for administraton. Consequently, stability information is needed for palonosetron HCl admixed in common infusion solutions. To evaluate the physical and chemical stability of palonosetron HCl in concentrations of 5 and 30 microg/mL in dextrose 5% injection, NaCl 0.9% injection, dextrose 5% in NaCl 0.45% injection, and dextrose 5% in lactated Ringer's injection. Triplicate test samples of palonosetron HCl at each concentration in each diluent were tested. Samples were stored and evaluated at appropriate intervals for up to 48 hours at room temperature ( approximately 23 degrees C) and 14 days under refrigeration (4 degrees C). Physical stability was assessed using turbidimetric and particulate measurement, as well as visual inspection. Chemical stability was assessed by HPLC. All of the admixtures were initially clear and colorless when viewed in normal fluorescent room light and with a Tyndall beam. Measured turbidity and particulate content were low initially and remained low throughout the study. The drug concentration was unchanged in any of the samples at either temperature throughout the study. Palonosetron HCl is physically and chemically stable in all 4 common infusion solutions for at least 48 hours at room temperature and 14 days under refrigeration.

  18. Application of isotope-labelled compounds in the study of the chemical stability of pesticides

    International Nuclear Information System (INIS)

    Roesseler, M.; Luther, D.; Abendroth, H.C.; Koch, H.

    1980-01-01

    The user of pesticides requires specific biological modes of action from the corresponding commercial products. Impurities and degradation products may cause uncontrollable toxicological reactions. Profound knowledge of the chemical stability of the effective substance in question and its formulations under storage conditions as well as under those of analytical sample preparation and detection is required. Radioisotope labelled effective substances dimethoate and 1-butyl-amino-cyclohexane-phosphonic acid dibutyl ester are used to study storage stability of the pure effective substance and its formulations; effects of selected impurities, such as technical by-products, moisture or water content, binding or carrier materials, organic solvents, chemical stabilizers and other formulation components on storage properties; temperature dependence of storage stability; selection of suitable analytical techniques for quantitative determination of the effective substance without interference effects from any by-product; reduction of the necessary analytical expense; disclosure of sources of error in the application of usual analytical techniques; improvement of possibilities of an immediate and clearer discrimination between types and amounts of compounds in a chemical system consisting of one pesticide and its degradation or reaction products at the beginning and at the end of an experimental or reaction period. Radiochemical analytical techniques, such as radio thin-layer chromatography (also combined with liquid scintillation counting), radio gas chromatography, autoradiography and isotope dilution analysis were used. Results are discussed, especially of experiments on dimethoate and its technical by-products

  19. The stability of poly(2,2′-(m-phenylene)-5,5′-bibenzimidazole) membranes in aqueous potassium hydroxide

    DEFF Research Database (Denmark)

    Aili, David; Jankova Atanasova, Katja; Li, Qingfeng

    2015-01-01

    25wt%. This work is devoted to a comprehensive stability study of mPBI in aqueous KOH of different concentrations for up to 200 days under conditions relevant for electrochemical energy conversion technologies. The polymer membranes were kept at 88°C in aqueous KOH with concentrations ranging from 0...... to 50wt%, and the chemical and physicochemical changes were monitored. The degradation was connected to the hydrolysis of the polymer backbone and the degradation rate increased with increasing KOH concentration. In the lower concentration range mPBI proved to be stable but exhibited low ionic...... conductivity (10−4Scm−1). The preparation of a porous mPBI matrix was demonstrated as an effective approach to increase the ionic conductivity in the lower KOH concentration range, with great potential for further improvement through optimization of the porous structure....

  20. The use of microbial and chemical analyses to characterize the variations in fouling profile of seawater reverse osmosis (SWRO) membrane

    KAUST Repository

    Manes, Carmem Lara De O

    2013-01-01

    Biofouling of reverse osmosis (RO) membranes is one of the most common problems in desalinations plants reducing the efficiency of the water production process. The characterization of bacterial community composition from fouling layers as well as detailed analysis of surrounding chemical environment might reveal process specific bacterial groups/species that are involved in RO biofouling. In this study, advanced organics analytic methods (elemental analysis, FTIR, and ICP-OES) were combined with high-throughput 16S rRNA (pyro) sequencing to assess in parallel, the chemical properties and the active microbial community composition of SWRO membranes from a pilot desalination plant (MFT, Tarragona) in February 2011 and July 2011. Prefiltered ultrafiltration. waters fed SWRO membranes during third and fifth month of operation, respectively. SWRO samples were taken from three modules at different positions (first, fourth, and sixth) in order to investigate the spatial changes in fouling layers\\' chemical and microbiological composition. The overall assessment of chemical parameters revealed that fouling layers were mainly composed by bio and organic material (proteins and lipids). Ca and Fe were found to be the most abundant elements having an increasing concentration gradient according to the module position. Bacterial community composition of SWRO membranes is mostly represented by the Gammaproteobacteria class with interesting differences in genera/species spatial and temporal distribution. This preliminary result suggests that pretreatments and/or operational conditions might have selected different bacterial groups more adapted to colonize SWRO membranes. © 2013 Desalination Publications.

  1. Chemical derivation to enhance the chemical/oxidative stability of resorcinol-formaldehyde (R-F) resin

    International Nuclear Information System (INIS)

    Hubler, T.L.; Shaw, W.J.; Brown, G.N.; Linehan, J.C.; Franz, J.A.; Hart, T.R.; Hogan, M.O.

    1996-09-01

    Tank wastes at Hanford and SRS contain highly alkaline supernate solutions of conc. Na, K nitrates with large amounts of 137 Cs. It is desirable to remove and concentrate the highly radioactive fraction for vitrification. One candidate ion exchange material for removing the radiocesium is R-F resin. This report summarizes studies into synthesis and characterization of 4-derivatized R-F resins prepared in pursuit of more chemically/oxidatively robust resin. 85% 4-fluororesorcinol/15% phenol formaldehyde resin appears to have good stability in alkaline solution, although there may be some nucleophilic displacement reaction during synthesis; further studies are needed

  2. Chemical modifications to vesicle forming diblock copolymers: Development of smart functional polymersome membranes

    Science.gov (United States)

    Katz, Joshua S.

    2011-07-01

    A major limitation to current treatment regimens for diseases is the inability to adequately deliver therapeutics. Many routes to encapsulation of these materials have been explored to improve biodistribution and better protect encapsulants from harsh biological conditions. One vehicle particularly attractive for encapsulation of such materials is the polymersome. While promising for translation to clinical use, there are still limitations in polymer chemistry and resulting polymersome behavior that will slow their adaptation. This thesis addresses several of these limitations. The first major limitation to polymersomes is lack of control over their release rate. Release is generally by simple diffusion, leading to a burst. To address this burst, Aim 1 proposes a route to stabilizing polymersome membranes through their polymerization. PCL-PEG copolymers were terminally acrylated and the acrylates polymerized in the membrane following vesicle assembly. Polymerization enhanced mechanical robustness of the membranes and reduced diffusion of encapsulated contents. To ultimately trigger release, Aim 2 presents a novel route to synthesizing diblock copolymers, enabling insertion of a functional group at the blocks' junction. To facilitate triggering of release, we inserted UV-cleavable 2-nitrophenylalanine. Polymersomes assembled from this polymer collapse upon exposure to light and molecules release. Demonstrating further utility of this synthetic route, fluorescent vesicles were prepared using fluorescent lysine as the joining molecule. These vesicles labeled dendritic cells, providing a novel route to cell labeling and tracking. The second limitation to vesicles promising for biomedical applications (made of PCL-PEG) is their solid membranes. Aim 3 demonstrates partial (or full) replacement of the PCL block with a caprolactone analogue, TOSUO, which is non-crystalline and assembles into soft, deformable vesicles. Increasing TOSUO content in the copolymer leads to

  3. Thermal stability of Trichoderma reesei c30 cellulase and aspergillus niger; -glucosidase after ph and chemical modification

    Energy Technology Data Exchange (ETDEWEB)

    Woodward, J.; Whaley, K.S.; Zachry, G.S.; Wohlpart, D.L.

    1981-01-01

    Treatment of Trichoderma reesei C30 cellulase at pH 10.0 for 1 h at room temperature increased its pH and thermal stability. Chemical modification of the free epsilon-amino groups of cellulase at pH 10.0 resulted in no further increase in stability. Such chemical modification, however, decreased the thermal stability of the cellulose-cellulase complex. On the contrary, the chemical modification of Aspergillus niger glucosidase with glutaraldehyde at pH 8.0 increased the thermal stability of this enzyme.

  4. Thermal stability of Trichoderma reesei C30 cellulase and Aspergillus niger. beta. -glucosidase after pH and chemical modification

    Energy Technology Data Exchange (ETDEWEB)

    Woodward, J.; Whaley, K.S.; Zachry, G.S.; Wohlpart, D.L.

    1981-01-01

    Treatment of Trichoderma reesei C30 cellulase at pH 10.0 for 1 h at room temperature increased its pH and thermal stability. Chemical modification of the free epsilon-amino groups of cellulase at pH 10.0 resulted in no further increase in stability. Such chemical modification, however, decreased the thermal stability of the cellulose-cellulase complex. On the contrary, the chemical modification of Aspergillus niger ..beta..-glucosidase with glutaraldehyde at pH 8.0 increased the thermal stability of this enzyme.

  5. Membrane chemical reactor (MCR) combining photocatalysis and microfiltration for grey water treatment.

    Science.gov (United States)

    Rivero, M J; Parsons, S A; Jeffrey, P; Pidou, M; Jefferson, B

    2006-01-01

    Urban water recycling is now becoming an important issue where water resources are becoming scarce. This paper looks at reusing grey water; the preference is treatment processes based on biological systems to remove the dissolved organic content. Here, an alternative process, photocatalysis is discussed as it is an attractive technology that could be well-suited for treating the recalcitrant organic compounds found in grey water. The photocatalytic process oxidises organic reactants at a catalyst surface in the presence of ultraviolet light. Given enough exposure time, organic compounds will be oxidized into CO2 and water. The best contact is achieved in a slurry reactor but a second step to separate and recover the catalyst is need. This paper discusses a new membrane chemical reactor (MCR) combining photocatalysis and microfiltration for grey water treatment.

  6. Mathematical modelling of flux recovery during chemical cleaning of tubular membrane fouled with whey proteins

    Directory of Open Access Journals (Sweden)

    Marković Jelena Đ.

    2009-01-01

    Full Text Available Membrane process efficiency in the dairy industry is impaired by the formation of deposits during filtration processes. This work describes cleaning procedures for ceramic tubular membrane (50 nm fouled with whey proteins. Also, mathematical modelling was performed to obtain models which allow deeper insight into the mechanisms involved during cleaning procedures. The caustic solutions (0.2%w/w, 0.4%w/w and 1.0%w/w NaOH and the mixture of two commercial detergents (0.8%w/w P3-ultrasil 69+0.5% w/w P3-ultrasil 67 and 1.2% P3-ultrasil 69+0.75 P3-ultrasil 67 were used as chemical cleaning agents. The results showed that the best flux recovery was achieved with 0.4%w/w NaOH solution. After analyzing the experimental data, five parameter and six parameter kinetic models were suggested for alkali and detergent cleaning, respectively. The changes of total and specific resistances, as well as the change of the effective pore diameter and deposit thickness during cleaning are estimated by applying these models.

  7. RED WINE EXTRACT OBTAINED BY MEMBRANE-BASED SUPERCRITICAL FLUID EXTRACTION: PRELIMINARY CHARACTERIZATION OF CHEMICAL PROPERTIES.

    Directory of Open Access Journals (Sweden)

    W. Silva

    Full Text Available ABSTRACT This study aims to obtain an extract from red wine by using membrane-based supercritical fluid extraction. This technique involves the use of porous membranes as contactors during the dense gas extraction process from liquid matrices. In this work, a Cabernet Sauvignon wine extract was obtained from supercritical fluid extraction using pressurized carbon dioxide as solvent and a hollow fiber contactor as extraction setup. The process was continuously conducted at pressures between 12 and 18 MPa and temperatures ranged from 30 to 50ºC. Meanwhile, flow rates of feed wine and supercritical CO2 varied from 0.1 to 0.5 mL min-1 and from 60 to 80 mL min-1 (NCPT, respectively. From extraction assays, the highest extraction percentage value obtained from the total amount of phenolic compounds was 14% in only one extraction step at 18MPa and 35ºC. A summarized chemical characterization of the obtained extract is reported in this work; one of the main compounds in this extract could be a low molecular weight organic acid with aromatic structure and methyl and carboxyl groups. Finally, this preliminary characterization of this extract shows a remarkable ORAC value equal to 101737 ± 5324 µmol Trolox equivalents (TE per 100 g of extract.

  8. Chemical stability of fluorine-containing coatings of cold drying for radiation - protection technique articles

    International Nuclear Information System (INIS)

    Shigorina, I.I.; Zvyagintseva, N.V.; Egorov, B.N.

    1977-01-01

    The chemical stability of fluorolon coatings, which are not subjected to heat treatment or hot drying during application, has been studied. The test for layer life-time has been performed by submerging specimens in agressive medium. The time for one upper removable layer to fail under steady action of agressive liquid is found to be: > 12 months at 20 deg C, 6-9 months at 40 deg C; at 60 deg C the time of layer stability depends upon medium: 1 month for nitric, 2 months for acetic, 2-3 months for sulphuric and hydrochloric acid. The coatings are recommended for practical application in radiation-protective technique

  9. Molecular sieve adsorbents and membranes for applications in the production of renewable fuels and chemicals

    Science.gov (United States)

    Ranjan, Rajiv

    Metal organic frameworks (MOF), a new class of porous materials, have emerged as promising candidate for gas storage, separation membrane and chemical sensors. We used secondary growth method to grow microporous metal organic framework (MMOF) films on porous alumina supports. Examination of the film using SEM and XRD showed that the crystals were well inter-grown and preferentially oriented. Gas permeation study showed that membranes were defect free and moderate selectivity was achieved for H2/N2 gas pairs. The next project had to do with ethanol production from lignocellulosic biomass as an alternate energy source. However, toxic inhibitors produced from the hydrolysis of biomass decrease ethanol yield during the fermentation process. We demonstrated the use of zeolites for the pretreatment of hydrolyzate in order to remove inhibitors like 5-Hydroxymethylfurfuraldehyde (HMF) and furfural from aqueous solution. Zeolites exhibit preferential adsorption of the inhibitors and in effect improve the ethanol yield during fermentation. Ideal Adsorbed Solution Theory (IAST) was also used to predict adsorption isotherms for HMF-furfural mixtures using single component adsorption data. We also studied production of HMF, a potential substitute as a building block for plastic and chemical production, from renewable biomass resources. Catalytic dehydration of fructose for HMF production faces problems like low conversion and yield. Dimethyl sulfoxide (DMSO) can be used as the solvent as well as the catalyst resulting in high HMF yield. We studied a reaction-separation system for this dehydration reaction where the product (HMF) could be recovered by selective adsorption on solid adsorbents from the reaction mixture.

  10. Surface modification of reverse osmosis desalination membranes by thin-film coatings deposited by initiated chemical vapor deposition

    Energy Technology Data Exchange (ETDEWEB)

    Ozaydin-Ince, Gozde, E-mail: gozdeince@sabanciuniv.edu [Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139 (United States); Matin, Asif, E-mail: amatin@mit.edu [Department of Mechanical Engineering, King Fahd University of Petroleum and Minerals, Dhahran 31261 (Saudi Arabia); Khan, Zafarullah, E-mail: zukhan@mit.edu [Department of Mechanical Engineering, King Fahd University of Petroleum and Minerals, Dhahran 31261 (Saudi Arabia); Zaidi, S.M. Javaid, E-mail: zaidismj@kfupm.edu.sa [Department of Mechanical Engineering, King Fahd University of Petroleum and Minerals, Dhahran 31261 (Saudi Arabia); Gleason, Karen K., E-mail: kkgleasn@mit.edu [Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139 (United States)

    2013-07-31

    Thin-film polymeric reverse osmosis membranes, due to their high permeation rates and good salt rejection capabilities, are widely used for seawater desalination. However, these membranes are prone to biofouling, which affects their performance and efficiency. In this work, we report a method to modify the membrane surface without damaging the active layer or significantly affecting the performance of the membrane. Amphiphilic copolymer films of hydrophilic hydroxyethylmethacrylate and hydrophobic perfluorodecylacrylate (PFA) were synthesized and deposited on commercial RO membranes using an initiated chemical vapor deposition technique which is a polymer deposition technique that involves free-radical polymerization initiated by gas-phase radicals. Relevant surface characteristics such as hydrophilicity and roughness could be systematically controlled by varying the polymer chemistry. Increasing the hydrophobic PFA content in the films leads to an increase in the surface roughness and hydrophobicity. Furthermore, the surface morphology studies performed using the atomic force microscopy show that as the thickness of the coating increases average surface roughness increases. Using this knowledge, the coating thickness and chemistry were optimized to achieve high permeate flux and to reduce cell attachment. Results of the static bacterial adhesion tests show that the attachment of bacterial cells is significantly reduced on the coated membranes. - Highlights: • Thin films are deposited on reverse osmosis membranes. • Amphiphilic thin films are resistant to protein attachment. • The permeation performance of the membranes is not affected by the coating. • The thin film coatings delayed the biofouling.

  11. Porous polyoxadiazole membranes for harsh environment

    KAUST Repository

    Maab, Husnul

    2013-10-01

    A series of polyoxadiazoles with exceptionally high stability at temperatures as high as 370°C and in oxidative medium has been synthesized by polycondensation and manufactured into porous membranes by phase inversion. The membranes were characterized by thermal analysis (TGA), chemical stability was measured by immersion test, oxidative stability by Fenton\\'s test, pore diameter by porosimetry and the morphology by FESEM. The polymers are soluble only in sulfuric acid and are stable in organic solvents like NMP, THF and isopropanol. The membranes selectivity was confirmed by separation of polystyrene standards with different molecular weights. Most membranes were characterized as having a cut-off of 60,000. g/mol. Being stable under harsh environments, the membranes have incomparable characteristics with perspectives of application in chemical and pharmaceutical industry, catalytic reactors, in combination with oxidative processes and other applications so far envisioned only for ceramic membranes. © 2013.

  12. Glucose-Neopentyl Glycol (GNG) Amphiphiles for Membrane Protein Solubilization, Stabilization and Crystallization

    Science.gov (United States)

    Rana, Rohini R.; Gotfryd, Kamil; Rasmussen, Søren G. F.; Kruse, Andrew C.; Cho, Kyung Ho; Capaldi, Stefano; Carlsson, Emil; Kobilka, Brian; Loland, Claus J.; Gether, Ulrik; Banerjee, Surajit

    2012-01-01

    The development of a new class of surfactants for membrane protein manipulation, “GNG amphiphiles”, is reported. These amphiphiles display promising behavior for membrane proteins, as demonstrated recently by the high resolution structure of a sodium-pumping pyrophosphatase reported by Kellosalo et al. PMID:23165475

  13. Glucose-Neopentyl Glycol (GNG) Amphiphiles for Membrane Protein Solubilization, Stabilization and Crystallization

    OpenAIRE

    Chae, Pil Seok; Rana, Rohini R.; Gotfryd, Kamil; Rasmussen, Søren G. F.; Kruse, Andrew C.; Cho, Kyung Ho; Capaldi, Stefano; Carlsson, Emil; Kobilka, Brian; Loland, Claus J.; Gether, Ulrik; Banerjee, Surajit; Byrne, Bernadette; Lee, John K.; Gellman, Samuel H.

    2013-01-01

    The development of a new class of surfactants for membrane protein manipulation, “GNG amphiphiles”, is reported. These amphiphiles display promising behavior for membrane proteins, as demonstrated recently by the high resolution structure of a sodium-pumping pyrophosphatase reported by Kellosalo et al.

  14. Aquifex aeolicus membrane hydrogenase for hydrogen biooxidation: Role of lipids and physiological partners in enzyme stability and activity

    Energy Technology Data Exchange (ETDEWEB)

    Infossi, Pascale; Lojou, Elisabeth; Giudici-Orticoni, Marie-Therese [Unite de Bioenergetique et Ingenierie des Proteines, UPR 9036, Institut de Microbiologie de la Mediterranee - CNRS, 31 Chemin Joseph Aiguier, 13402 Marseille Cedex 20 (France); Chauvin, Jean-Paul [Institut de Biologie du developpement de Marseille Luminy, UMR 6216, Parc Scientifique de Luminy, 163 Avenue de Luminy, BP 907, 13009 Marseille (France); Herbette, Gaetan [Spectropole FI 1739, Aix-Marseille Universite case 511, Faculte de St Jerome Avenue Escadrille Normandie Niemen, 13397 Marseille Cedex 20 (France); Brugna, Myriam [Unite de Bioenergetique et Ingenierie des Proteines, UPR 9036, Institut de Microbiologie de la Mediterranee - CNRS, 31 Chemin Joseph Aiguier, 13402 Marseille Cedex 20 (France); Universite de Provence, 3 Place Victor Hugo, 13331 Marseille Cedex 03 (France)

    2010-10-15

    Hydrogenase I from the hyperthermophilic bacterium Aquifex aeolicus is a good candidate for biotechnological devices thanks to its ability to oxidize hydrogen at high temperature, even in the presence of oxygen and CO. In order to enhance the enzyme stability and the catalytic efficiency, we investigated the hydrogen oxidation process with hydrogenase I embedded in a physiological-like environment. Hydrogenase I partners in the metabolic chain, namely membrane quinone and cytochrome b, were purified and fully characterized. The complex hydrogenase I-cytochrome b was inserted into liposomes. Surface Plasmon Resonance revealed that quinone took part in the stabilization of the complex. By use of molecular modelization and electrochemistry analysis, enzyme stability has been demonstrated to be stronger and enzymatic efficiency to be five times higher when hydrogenase is embedded into the liposomes. This result raises the possibility of using hydrogenases as biocatalysts in fuel cells. (author)

  15. Structure of anti-FLAG M2 Fab domain and its use in the stabilization of engineered membrane proteins

    International Nuclear Information System (INIS)

    Roosild, Tarmo P.; Castronovo, Samantha; Choe, Senyon

    2006-01-01

    The X-ray crystallographic analysis of anti-FLAG M2 Fab is reported and the implications of the structure on FLAG epitope binding are described as a first step in the development of a tool for the structural and biophysical study of membrane proteins. The inherent difficulties of stabilizing detergent-solubilized integral membrane proteins for biophysical or structural analysis demand the development of new methodologies to improve success rates. One proven strategy is the use of antibody fragments to increase the ‘soluble’ portion of any membrane protein, but this approach is limited by the difficulties and expense associated with producing monoclonal antibodies to an appropriate exposed epitope on the target protein. Here, the stabilization of a detergent-solubilized K + channel protein, KvPae, by engineering a FLAG-binding epitope into a known loop region of the protein and creating a complex with Fab fragments from commercially available anti-FLAG M2 monoclonal antibodies is reported. Although well diffracting crystals of the complex have not yet been obtained, during the course of crystallization trials the structure of the anti-FLAG M2 Fab domain was solved to 1.86 Å resolution. This structure, which should aid future structure-determination efforts using this approach by facilitating molecular-replacement phasing, reveals that the binding pocket appears to be specific only for the first four amino acids of the traditional FLAG epitope, namely DYKD. Thus, the use of antibody fragments for improving the stability of target proteins can be rapidly applied to the study of membrane-protein structure by placing the short DKYD motif within a predicted peripheral loop of that protein and utilizing commercially available anti-FLAG M2 antibody fragments

  16. Real cause of detrimental carbonation in chemically stabilized layers and possible solutions

    CSIR Research Space (South Africa)

    Botha, PB

    2005-10-01

    Full Text Available to determine the other reaction that may take place in the material. KEYWORDS CARBONATION/ CHEMICAL REACTIONS/ WATER CURING/ NEW TESTING PROTOCOL 1 INTRODUCTION This paper deals with the problems related to the “curing” of the stabilized layers... than CO2 driven. In actually fact the so-called “detrimental carbonation” chemical reaction cannot even take place without free water being available. The water is normally supplied by the specified curing 2 technique to keep the layer moist...

  17. Characterization of milk proteins-lutein complexes and the impact on lutein chemical stability.

    Science.gov (United States)

    Yi, Jiang; Fan, Yuting; Yokoyama, Wallace; Zhang, Yuzhu; Zhao, Liqing

    2016-06-01

    In this study, the interaction of WPI (whey protein isolate) and SC (sodium caseinate) with hydrophobic lutein was investigated through UV-vis spectroscopy and circular dichroism (CD) as well as fluorescence. The effects on lutein's chemical stability were also examined. The decrease of turbidity of lutein suggested that lutein's aqueous solubility was improved after binding with milk proteins. CD analysis indicated lutein had little impact on the secondary structures of both proteins. Different preparation methods have significant impacts on the binding constant. Fluorescence results indicated that WPI and SC interact with lutein by hydrophobic contacts. Milk proteins have protective effects on lutein against oxidation and decomposition, and SC showed better capability in protecting lutein from oxidation than WPI during 16 days storage. The lutein's chemical stability was increased with increasing of proteins concentration. The results indicated that milk proteins may act as effective carriers for lipophilic nutraceuticals. Copyright © 2016 Elsevier Ltd. All rights reserved.

  18. Metal and anion composition of two biopolymeric chemical stabilizers and toxicity risk implication for the environment.

    Science.gov (United States)

    Ndibewu, P P; Mgangira, M B; Cingo, N; McCrindle, R I

    2010-01-01

    The objective of this study was to (1) measure the concentration of four anions (Cl(-), F(-), [image omitted], and [image omitted]) and nine other elements (Al, Ba, Ca, K, Mg, Mn, Fe, Ni, and Si) in two nontraditional biopolymeric chemical stabilizers (EBCS1 and EBCS2), (2) investigate consequent environmental toxicity risk implications, and (3) create awareness regarding environmental health issues associated with metal concentration levels in enzyme-based chemical stabilizers that are now gaining widespread application in road construction and other concrete materials. Potential ecotoxicity impacts were studied on aqueous extracts of EBCS1 and EBCS2 using two thermodynamic properties models: the Pitzer-Mayorga model (calculation of the electrolyte activity coefficients) and the Millero-Pitzer model (calculation of the ionic activity coefficients). Results showed not only high concentrations of a variety of metal ions and inorganic anions, but also a significant variation between two chemical stabilizing mixtures. The mixture (EBCS2) with the lower pH value was richer in all the cationic and anionic species than (EBCS1). Sulfate (SO(2-)(4)) concentrations were found to be higher in EBCS2 than in EBCS1. There was no correlation between electrolyte activity and presence of the ionic species, which may be linked to a possible high ionic environmental activity. The concentrations of trace metals found (Mn, Fe, and Ni) were low compared to those of earth metals (Ba, Ca, K, and Mg). The metal concentrations were higher in EBCS1 than in EBCS2. Data suggest that specific studies are needed to establish "zero" permissible metal ecotoxicity values for elements and anions in any such strong polyelectrolytic enzyme-based chemical stabilizers.

  19. A high throughput platform for understanding the influence of excipients on physical and chemical stability

    DEFF Research Database (Denmark)

    Raijada, Dhara; Cornett, Claus; Rantanen, Jukka

    2013-01-01

    The present study puts forward a miniaturized high-throughput platform to understand influence of excipient selection and processing on the stability of a given drug compound. Four model drugs (sodium naproxen, theophylline, amlodipine besylate and nitrofurantoin) and ten different excipients were...... for chemical degradation. The proposed high-throughput platform can be used during early drug development to simulate typical processing induced stress in a small scale and to understand possible phase transformation behaviour and influence of excipients on this....

  20. Chemical structure and radiation stability of solid crystalline antibiotics: thiamphenicol and chloramphenicol

    International Nuclear Information System (INIS)

    Varshney, Lalit; Soe Nwe

    1997-01-01

    Antibiotics in solid state show significant radiation resistance and some of them are exposed to gamma or electron beam irradiation for sterilization. Even small radiation degradation in solid state antibiotics is not desirable. Two antibiotics namely thiamphenicol (TPL) and chloramphenicol (CPL) having similar chemical and solid state structure were irradiated at different graded radiation doses to study their stability. Differential scanning calorimetry (DSC) was used to evaluate purity, entropy of radiation processing, heat of fusion and melting point. (author). 3 refs., 1 tab

  1. The chemical modification and characterization of polypropylene membrane with environment response by in-situ chlorinating graft copolymerization

    Science.gov (United States)

    Zhang, Yue; Liu, Jiankai; Hu, Wenjie; Feng, Ying; Zhao, Jiruo

    2017-08-01

    In this study, a novel chemical surface modification method of polyolefin membranes is applied following the in-situ chlorinating graft copolymerization (ISCGC). Polypropylene (PP)/methyl methacrylate (MMA) system was used as an example. A unique structure was formed by the modification process on the original membrane surface and the product exhibited an environmental response. Chlorine free radicals were generated using ultraviolet and heat and were used to capture the hydrogen in the polymer chains on the substrate surface. The formed macromolecular radicals could react with MMA over 2 h to achieve a high coverage ratio polymer on the PP membrane surface. The graft copolymers were characterized using FTIR, 1H-NMR, DSC, and XPS, which all proved the feasibility of chemically modifying the PP membrane surface by ISCGC. The surface morphology of the grafted PP membrane was characterized using SEM and AFM. The results showed that the grafted product presents a uniform, neat, and dense mastoid structure with an average thickness of 4.44 μm, which was expected to be similar to the brush-like surface structure. The contact angle and AFM tests indicated that the product surface is responsive to solvent and pH. The experimental results showed that the PP membrane surface structure can be reconstructed using ISCGC, a method that can be used for environment-responsive polymer materials. Moreover, the product has the characteristics of polymer interfacial brush.

  2. Enhancement of the chemical stability in confined δ-Bi2O3

    DEFF Research Database (Denmark)

    Sanna, Simone; Esposito, Vincenzo; Andreasen, Jens Wenzel

    2015-01-01

    Bismuth-oxide-based materials are the building blocks for modern ferroelectrics1, multiferroics2, gas sensors3, light photocatalysts4 and fuel cells5,6. Although the cubic fluorite δ-phase of bismuth oxide (δ-Bi2O3) exhibits the highest conductivity of known solid-state oxygen ion conductors5, its...... instability prevents use at low temperature7–10. Here we demonstrate the possibility of stabilizing δ-Bi2O3 using highly coherent interfaces of alternating layers of Er2O3-stabilized δ-Bi2O3 and Gd2O3-doped CeO2. Remarkably, an exceptionally high chemical stability in reducing conditions and redox cycles...

  3. On the stabilizing role of species diffusion in chemical enhanced oil recovery

    Science.gov (United States)

    Daripa, Prabir; Gin, Craig

    2015-11-01

    In this talk, the speaker will discuss a problem on the stability analysis related to the effect of species diffusion on stabilization of fingering in a Hele-Shaw model of chemical enhanced oil recovery. The formulation of the problem is motivated by a specific design principle of the immiscible interfaces in the hope that this will lead to significant stabilization of interfacial instabilities, there by improving oil recovery in the context of porous media flow. Testing the merits of this hypothesis poses some challenges which will be discussed along with some numerical results based on current formulation of this problem. Several open problems in this context will be discussed. This work is currently under progress. Supported by the grant NPRP 08-777-1-141 from the Qatar National Research Fund (a member of The Qatar Foundation).

  4. Effect of stabilization temperature during pyrolysis process of P84 co-polyimide-based tubular carbon membrane for H2/N2 and He/N2 separations

    Science.gov (United States)

    Sazali, N.; Salleh, W. N. W.; Ismail, A. F.; Ismail, N. H.; Aziz, F.; Yusof, N.; Hasbullah, H.

    2018-04-01

    In this study, the effect of stabilization temperature on the performance of tubular carbon membrane was being investigated. P84 co-polyimide-based tubular carbon membrane will be fabricated through the dip-coating technique. The tubular carbon membrane performance can be controlled by manipulating the pyrolysis conditions which was conducted at different stabilization temperatures of 250, 300, 350, 400, and 450°C under N2 environment (200 ml/min). The prepared membranes were characterized by using scanning electron microscopy (SEM), x-ray diffraction (XRD), and pure gas permeation system. The pure gas of H2, He, and N2 were used to determine the permeation properties of the carbon membrane. The P84 co-polyimide-based tubular carbon membrane stabilized at 300°C demonstrated an excellent permeation property with H2, He, and N2 gas permeance of 1134.51±2.87, 1287.22±2.86 and 2.98±1.28GPU, respectively. The highest H2/N2 and He/N2 selectivity of 380.71±2.34 and 431.95±2.61 was obtained when the stabilization temperature of 450°C was applied. It is concluded that the stabilization temperatures have protrusive effect on the carbon membrane properties specifically their pore structure, and eventually their gas separation properties.

  5. Thermal and chemical stabilities of some synthesized inorganic ion exchange materials

    International Nuclear Information System (INIS)

    EI-Naggar, I.M.; Abou-Mesalam, M.M.; El-Shorbagy, M.M.; Shady, S.A.

    2006-01-01

    Chromium and cerium titanate as inorganic ion exchange materials were synthesized by the reaction of potassium chromate or ammonium eerie nitrate with titanium tetrachloride with molar ratio equal unity. The crystal system of both chromium and cerium titanates were determined and set to be monoclinic and orthorhombic system's, respectively. The chemical composition of both chromium and cerium titanates was determined by X-ray fluorescence technique and based on the data obtained with other different techniques. A molecular formula for chromium and cerium titanates as Cr 2 Ti 12 O 27 . 13H 2 O and Ce 2 Ti 3 O 10 . 7.46H 2 O, respectively, was proposed. Thermal stabilities of both ion exchangers were investigated at different heating temperatures. Also the stability of chromium and cerium titanates for chemical attack was studied in different media. The data obtained showed high thermal and chemical stabilities of chromium and cerium titanate ion exchangers compared with the same group of ion exchange materials. The ion exchange capacities of chromium and cerium titanates at different heating temperature were also investigated

  6. Thermal and chemical stabilities of some synthesized inorganic ion exchange materials

    International Nuclear Information System (INIS)

    El-Naggar, I.M.; Abou-Mesalam, M. M.; El-Shorbagy, M.M.; Shady, S.A.

    2005-01-01

    Chromium and cerium titanate as inorganic ion exchange materials were synthesized by the reaction of potassium chromate or ammonium ceric nitrate with titanium tetrachloride with molar ratio equal unity. The crystal system of both chromium and cerium titanates were determined and set to be monoclinic and orthorhombic systems, respectively. The chemical composition of both chromium and cerium titanates were determined by X-ray fluorescence technique and based on the data obtained with other different techniques. We can proposed molecular formula for chromium and cerium titanates as Cr 2 Ti 1 2O27. 13H 2 O and Ce 2 ThO10. 7.46 H 2 O, respectively. Thermal stability of both ion exchangers was investigated at different heating temperatures. Also the stability of chromium and cerium titanates for chemical attack was studied in different media. The data obtained showed high thermal and chemical stabilities of chromium and cerium titanate ion exchangers compared to the same group of ion exchange materials. The ion exchange capacities of chromium and cerium titanates at different heating temperature were investigated

  7. Formulation design of oral pediatric Acetazolamide suspension: dose uniformity and physico-chemical stability study.

    Science.gov (United States)

    Santoveña, Ana; Suárez-González, Javier; Martín-Rodríguez, Cristina; Fariña, José B

    2017-03-01

    The formulation of an active pharmaceutical ingredient (API) as oral solution or suspension in pediatrics is a habitual practice, due to the non-existence of many commercialized medicines in pediatric doses. It is also the simplest way to prepare and administer them to this vulnerable population. The design of a formulation that assures the dose and the system stability depends on the physico-chemical properties of the API. In this study, we formulate a class IV API, Acetazolamide (AZM) as suspension for oral administration to pediatric population. The suspension must comply attributes of quality, safety and efficacy for this route of administration. We use simple compounding procedures, as well as fewer pure excipients, as recommended for children. Mass and uniformity content assays and physical and chemical stability studies were performed. To quantify the API an UPLC method was used. We verified the physico-chemical stability of the suspensions and that they passed the mass test of the European Pharmacopeia (EP), but not the dose uniformity test. This reveals that AZM must be formulated as liquid forms with a more complex system of excipients (not usually indicated in pediatrics), or otherwise solid forms capable of assuring uniformity of mass and dose for every dosage unit.

  8. Comparing the short and long term stability of biodegradable, ceramic and cation exchange membranes in microbial fuel cells.

    Science.gov (United States)

    Winfield, Jonathan; Chambers, Lily D; Rossiter, Jonathan; Ieropoulos, Ioannis

    2013-11-01

    The long and short-term stability of two porous dependent ion exchange materials; starch-based compostable bags (BioBag) and ceramic, were compared to commercially available cation exchange membrane (CEM) in microbial fuel cells. Using bi-directional polarisation methods, CEM exhibited power overshoot during the forward sweep followed by significant power decline over the reverse sweep (38%). The porous membranes displayed no power overshoot with comparably smaller drops in power during the reverse sweep (ceramic 8%, BioBag 5.5%). The total internal resistance at maximum power increased by 64% for CEM compared to 4% (ceramic) and 6% (BioBag). Under fixed external resistive loads, CEM exhibited steeper pH reductions than the porous membranes. Despite its limited lifetime, the BioBag proved an efficient material for a stable microbial environment until failing after 8 months, due to natural degradation. These findings highlight porous separators as ideal candidates for advancing MFC technology in terms of cost and operation stability. Copyright © 2013 Elsevier Ltd. All rights reserved.

  9. The Effects of Lyophilization on the Physico-Chemical Stability of Sirolimus Liposomes

    Directory of Open Access Journals (Sweden)

    Parvin Zakeri-Milani

    2013-02-01

    Full Text Available Purpose: The major limitation in the widespread use of liposome drug delivery system is its instability. Lyophilization is a promising approach to ensure the long-term stability of liposomes. The aim of this study was to prepare sirolimus-loaded liposomes, study their stability and investigate the effect of lyophilization either in the presence or in the absence of lyoprotectant on liposome properties. Methods: Two types of multi-lamellar liposomes, conventional and fusogenic, containing sirolimus were prepared by modified thin film hydration method with different ratio of dipalmitoylphosphatidylcholine (DPPC, cholesterol and dioleoylphosphoethanolamine (DOPE, and were lyophilized with or without dextrose as lyoprotectant. Chemical stability investigation was performed at 4°C and 25°C until 6 months using a validated HPLC method. Physical stability was studied with determination of particle size (PS and encapsulation efficiency (EE % of formulations through 6 months. Results: Chemical stability test at 4°C and 25°C until 6 months showed that drug content of liposomes decreased 8.4% and 20.2% respectively. Initial mean EE % and PS were 72.8 % and 582 nm respectively. After 6 months mean EE % for suspended form, lyophilized without lyoprotectant and lyophilized with lyoprotectant were 54.8 %, 62.3% and 67.1 % at 4°C and 48.2%, 60.4 % and 66.8 % at 25°C respectively. Corresponding data for mean PS were 8229 nm, 2397 nm and 688nm at 4°C and 9362 nm, 1944 nm and 737 nm at 25°C respectively. Conclusion: It is concluded that lyophilization with and without dextrose could increase shelf life of liposome and dextrose has lyoprotectant effect that stabilized liposomes in the lyophilization process.

  10. Physical and chemical stability of proflavine contrast agent solutions for early detection of oral cancer.

    Science.gov (United States)

    Kawedia, Jitesh D; Zhang, Yan-Ping; Myers, Alan L; Richards-Kortum, Rebecca R; Kramer, Mark A; Gillenwater, Ann M; Culotta, Kirk S

    2016-02-01

    Proflavine hemisulfate solution is a fluorescence contrast agent to visualize cell nuclei using high-resolution optical imaging devices such as the high-resolution microendoscope. These devices provide real-time imaging to distinguish between normal versus neoplastic tissue. These images could be helpful for early screening of oral cancer and its precursors and to determine accurate margins of malignant tissue for ablative surgery. Extemporaneous preparation of proflavine solution for these diagnostic procedures requires preparation in batches and long-term storage to improve compounding efficiency in the pharmacy. However, there is a paucity of long-term stability data for proflavine contrast solutions. The physical and chemical stability of 0.01% (10 mg/100 ml) proflavine hemisulfate solutions prepared in sterile water was determined following storage at refrigeration (4-8℃) and room temperature (23℃). Concentrations of proflavine were measured at predetermined time points up to 12 months using a validated stability-indicating high-performance liquid chromatography method. Proflavine solutions stored under refrigeration were physically and chemically stable for at least 12 months with concentrations ranging from 95% to 105% compared to initial concentration. However, in solutions stored at room temperature increased turbidity and particulates were observed in some of the tested vials at 9 months and 12 months with peak particle count reaching 17-fold increase compared to baseline. Solutions stored at room temperature were chemically stable up to six months (94-105%). Proflavine solutions at concentration of 0.01% were chemically and physically stable for at least 12 months under refrigeration. The solution was chemically stable for six months when stored at room temperature. We recommend long-term storage of proflavine solutions under refrigeration prior to diagnostic procedure. © The Author(s) 2014.

  11. Chemical stability of insulin. 4. Mechanisms and kinetics of chemical transformations in pharmaceutical formulation.

    Science.gov (United States)

    Brange, J

    1992-01-01

    Insulin decomposes by a multitude of chemical reactions [1-3]. It deamidates at two different residues by entirely different mechanisms. In acid, deamidation at AsnA21 is intramolecularly catalyzed by the protonated C-terminal, whereas above pH 6 an intermediate imide formation at residue AsnB3 leads to isoAsp and Asp derivatives. The imide formation requires a large rotation around the alpha-carbon/peptide carbonyl carbon bond at B3, corresponding to a 10 A movement of the B-chain N-terminal. The main determinant for the rate of B3 deamidation, as well as for the ratio between the two products formed, is the local conformational structure, which is highly influenced by various excipients and the physical state of the insulin. An amazing thermolysin-like, autoproteolytic cleavage of the A-chain takes place in rhombohedral insulin crystals, mediated by a concerted catalytic action by several, inter-hexameric functional groups and Zn2+. Intermolecular, covalent cross-linking of insulin molecules occurs via several mechanisms. The most prominent type of mechanism is aminolysis by the N-terminals, leading to isopeptide linkages with the A-chain side-chain amides of residues GlnA15, AsnA18 and AsnA21. The same type of reaction also leads to covalent cross-linking of the N-terminal in protamine with insulin. Disulfide exchange reactions, initiated by lysis of the A7-B7 disulfide bridge, lead mainly to formation of covalent oligo- and polymers. Activation energy (Ea) for the neutral deamidation and the aminolysis reactions was found to be 80 and 119 KJ/mol, respectively.

  12. RNS60, a charge-stabilized nanostructure saline alters Xenopus Laevis oocyte biophysical membrane properties by enhancing mitochondrial ATP production

    Science.gov (United States)

    Choi, Soonwook; Yu, Eunah; Kim, Duk-Soo; Sugimori, Mutsuyuki; Llinás, Rodolfo R

    2015-01-01

    We have examined the effects of RNS60, a 0.9% saline containing charge-stabilized oxygen nanobubble-based structures. RNS60 is generated by subjecting normal saline to Taylor–Couette–Poiseuille (TCP) flow under elevated oxygen pressure. This study, implemented in Xenopus laevis oocytes, addresses both the electrophysiological membrane properties and parallel biological processes in the cytoplasm. Intracellular recordings from defolliculated X. laevis oocytes were implemented in: (1) air oxygenated standard Ringer's solution, (2) RNS60-based Ringer's solution, (3) RNS10.3 (TCP-modified saline without excess oxygen)-based Ringer's, and (4) ONS60 (saline containing high pressure oxygen without TCP modification)-based Ringer's. RNS60-based Ringer's solution induced membrane hyperpolarization from the resting membrane potential. This effect was prevented by: (1) ouabain (a blocker of the sodium/potassium ATPase), (2) rotenone (a mitochondrial electron transfer chain inhibitor preventing usable ATP synthesis), and (3) oligomycin A (an inhibitor of ATP synthase) indicating that RNS60 effects intracellular ATP levels. Increased intracellular ATP levels following RNS60 treatment were directly demonstrated using luciferin/luciferase photon emission. These results indicate that RNS60 alters intrinsic the electrophysiological properties of the X. laevis oocyte membrane by increasing mitochondrial-based ATP synthesis. Ultrastructural analysis of the oocyte cytoplasm demonstrated increased mitochondrial length in the presence of RNS60-based Ringer's solution. It is concluded that the biological properties of RNS60 relate to its ability to optimize ATP synthesis. PMID:25742953

  13. Processing and stabilization of Aloe Vera leaf gel by adding chemical and natural preservatives

    Directory of Open Access Journals (Sweden)

    N. Nazemi

    2017-11-01

    Full Text Available Background and objectives: Aloe vera has been used as a medicinal herb for thousands of years. Aloe vera leaves can be separated into latex and gel which have biological effects. Aloe gel is a potent source of polysaccharides. When the gel is exposed to air, it quickly decomposes and decays and loses most of its biological activity. There are various processing techniques for sterilizing and stabilizing the gel. The aim of this study was to improve stabilization of the gel by adding some chemical and natural preservatives. Methods: The gel was obtained from Aloe vera leaves and after some processing chemical and natural preservatives were added. Chemicals included citric acid, ascorbic acid, vitamin E and potassium sorbate while natural preservatives were two essential oils derived from Cinnamomum zeylanicum and Eugenia caryophyllata. All these operations were performed under sterile conditions and they were evaluated at different temperatures and times. Appearance and taste changes of gel were studied organoleptic. Microbiological tests and some physical assays such as pH, refractometry and viscosity properties as well as determination of total sugars were measured. NMR and FT-IR analyses were performed for determining the quality of samples. Results: After data analyzing, the results showed that the samples formulated with chemical additives together with essential oils were more suitable and stable compared to the control samples after 90 days and the effective ingredient acemannan, remained stable. Conclusion: The stable gel can be considered for therapeutic properties and be used for edible and medicinal purposes.

  14. Rapid continuous chemical methods for studies of nuclei far from stability

    CERN Document Server

    Trautmann, N; Eriksen, D; Gaggeler, H; Greulich, N; Hickmann, U; Kaffrell, N; Skarnemark, G; Stender, E; Zendel, M

    1981-01-01

    Fast continuous separation methods accomplished by combining a gas-jet recoil-transport system with a variety of chemical systems are described. Procedures for the isolation of individual elements from fission product mixtures with the multistage solvent extraction facility SISAK are presented. Thermochromatography in connection with a gas-jet has been studied as a technique for on-line separation of volatile fission halides. Based on chemical reactions in a gas-jet system itself separation procedures for tellurium, selenium and germanium from fission products have been worked out. All the continuous chemical methods can be performed within a few seconds. The application of such procedures to the investigation of nuclides far from the line of beta -stability is illustrated by a few examples. (16 refs).

  15. The physical and chemical stability of suspensions of sustained-release diclofenac microspheres.

    Science.gov (United States)

    Lewis, L; Boni, R L; Adeyeye, C M

    1998-01-01

    The major challenge in liquid sustained-release oral suspensions is to minimize drug diffusion into the suspending medium and to retain the original properties of the microparticles during storage. Diclofenac wax microspheres prepared by the hydrophobic congealable disperse phase method were formulated as a sustained release suspension and stored at three different temperatures (25, 37 and 45 degrees C) for 3 months, to evaluate the physical and chemical stability of the suspended microspheres. Suspensions of microspheres stored at ambient temperatures were both physically and chemically stable, but at higher temperatures, up to 45 degrees C, there was a decrease in drug release due to scaling and melting on the microsphere surface as observed by scanning electron microscopy. However, on prolonged storage, up to 90 days, especially at 45 degrees C, temperature became a dominant factor causing an increase in drug release. The suspension of diclofenac microspheres was chemically stable for 3 months, while the plain drug suspension exhibited slight degradation.

  16. Chemical properties and oxidative stability of Arjan (Amygdalus reuteri) kernel oil as emerging edible oil.

    Science.gov (United States)

    Tavakoli, Javad; Emadi, Teymour; Hashemi, Seyed Mohammad Bagher; Mousavi Khaneghah, Amin; Munekata, Paulo Eduardo Sichetti; Lorenzo, Jose Manuel; Brnčić, Mladen; Barba, Francisco J

    2018-05-01

    The oxidative stability, as well as the chemical composition of Amygdalus reuteri kernel oil (ARKO), were evaluated and compared to those of Amygdalus scoparia kernel oil (ASKO) and extra virgin olive oil (EVOO) during and after holding in the oven (170 °C for 8 h). The oxidative stability analysis was carried out by measuring the changes in conjugated dienes, carbonyl and acid values as well as oil/oxidative stability index and their correlation with the antioxidant compounds (tocopherol, polyphenols, and sterol compounds). The oleic acid was determined as the predominant fatty acid of ARKO (65.5%). Calculated oxidizability value and an iodine value of ARKO, ASKO and EVOO were reported as 3.29 and 3.24, 2.00 and 100.0, 101.4 and 81.9, respectively. Due to the high wax content (4.5% and 3.3%, respectively), the saponification number of ARKO and ASKO (96.4 and 99.8, respectively) was lower than that of EVOO (169.7). ARKO had the highest oxidative stability, followed by ASKO and EVOO. Therefore, ARKO can be introduced as a new source of edible oil with high oxidative stability. Copyright © 2018. Published by Elsevier Ltd.

  17. ZIFL1.1 transporter modulates polar auxin transport by stabilizing membrane abundance of multiple PINs in Arabidopsis root tip

    Science.gov (United States)

    Remy, Estelle; Baster, Pawel; Friml, Jiří; Duque, Paula

    2013-01-01

    Cell-to-cell directional flow of the phytohormone auxin is primarily established by polar localization of the PIN auxin transporters, a process tightly regulated at multiple levels by auxin itself. We recently reported that, in the context of strong auxin flows, activity of the vacuolar ZIFL1.1 transporter is required for fine-tuning of polar auxin transport rates in the Arabidopsis root. In particular, ZIFL1.1 function protects plasma-membrane stability of the PIN2 carrier in epidermal root tip cells under conditions normally triggering PIN2 degradation. Here, we show that ZIFL1.1 activity at the root tip also promotes PIN1 plasma-membrane abundance in central cylinder cells, thus supporting the notion that ZIFL1.1 acts as a general positive modulator of polar auxin transport in roots. PMID:23857365

  18. Idaho Chemical Processing Plant low-level waste grout stabilization development program FY-96 status report

    International Nuclear Information System (INIS)

    Herbst, A.K.

    1996-09-01

    The general purpose of the Grout Stabilization Development Program is to solidify and stabilize the liquid low-level wastes (LLW) generated at the Idaho Chemical Processing Plant (ICPP). It is anticipated that LLW will be produced from the following: (1) chemical separation of the tank farm high-activity sodium-bearing waste; (2) retrieval, dissolution, and chemical separation of the aluminum, zirconium, and sodium calcines; (3) facility decontamination processes; and (4) process equipment waste. The main tasks completed this fiscal year as part of the program were chromium stabilization study for sodium-bearing waste and stabilization and solidification of LLW from aluminum and zirconium calcines. The projected LLW will be highly acidic and contain high amounts of nitrates. Both of these are detrimental to Portland cement chemistry; thus, methods to precondition the LLW and to cure the grout were explored. A thermal calcination process, called denitration, was developed to solidify the waste and destroy the nitrates. A three-way blend of Portland cement, blast furnace slag, and fly ash was successfully tested. Grout cubes were prepared at various waste loadings to maximize loading while meeting compressive strength and leach resistance requirements. For the sodium LLW, a 25% waste loading achieves a volume reduction of 3.5 and a compressive strength of 2,500 pounds per square inch while meeting leach, mix, and flow requirements. It was found that the sulfur in the slag reduces the chromium leach rate below regulatory limits. For the aluminum LLW, a 15% waste loading achieves a volume reduction of 8.5 and a compressive strength of 4,350 pounds per square inch while meeting leach requirements. Likewise for zirconium LLW, a 30% waste loading achieves a volume reduction of 8.3 and a compressive strength of 3,570 pounds per square inch

  19. Analyte-triggered luminescence of Eu{sup 3+} ions encapsulated in Nafion membranes -preparation of hybrid materials from in membrane chemical reactions-

    Energy Technology Data Exchange (ETDEWEB)

    Aguilar-Sánchez, Rocío, E-mail: raguilar@ifuap.buap.mx [Depto. Química Analítica, Facultad de Ciencias Químicas, Benemérita Universidad Autónoma de Puebla, Puebla 72570 (Mexico); Zelocualtecatl-Montiel, Iván [Depto. Química Analítica, Facultad de Ciencias Químicas, Benemérita Universidad Autónoma de Puebla, Puebla 72570 (Mexico); Gálvez-Vázquez, María de Jesús [Depto. Química Analítica, Facultad de Ciencias Químicas, Benemérita Universidad Autónoma de Puebla, Puebla 72570 (Mexico); Instituto de Física, Benemérita Universidad Autónoma de Puebla, Apartado postal J-48, Puebla 72570 (Mexico); Silva-González, Rutilo [Instituto de Física, Benemérita Universidad Autónoma de Puebla, Apartado postal J-48, Puebla 72570 (Mexico)

    2017-04-15

    The possibility to perform chemical reactions inside polymer materials opens a unique opportunity to control and prepare materials for diverse solid-state applications. Based on the affinity of Eu{sup 3+} ions for oxygen functionalities, in this work we report the luminescence enhancement of Eu{sup 3+} ions inserted in Nafion membranes (Naf/Eu{sup 3+}) by in-situ complexing to oxalate. The formation of a europium-oxalate type complex enhances Eu{sup 3+} luminescence emission, which could be exploited for the construction of devices for oxalate sensing and the fabrication of highly luminescent materials. Possible analytical applications of Naf/Eu{sup 3+} membranes were evaluated by fluorescence spectroscopy through the linear response with concentration. The complex formation was followed by infrared spectroscopy and SEM-EDS analysis. - Highlights: • Luminescence enhancement by complexation of Eu{sup 3+} ions to oxalate inside Nafion. • Performance of chemical reactions inside Nafion/polymer membranes. • An easy and novel method to prepare luminescent solid devices. • Possibility to develop luminescent sensors by analyte-triggered optical response.

  20. Microvillar membrane microdomains exist at physiological temperature. Role of galectin-4 as lipid raft stabilizer revealed by "superrafts"

    DEFF Research Database (Denmark)

    Braccia, Anita; Villani, Maristella; Immerdal, Lissi

    2003-01-01

    rafts prepared by the two protocols were morphologically different but had essentially similar profiles of protein- and lipid components, showing that raft microdomains do exist at 37 degrees C and are not "low temperature artifacts." We also employed a novel method of sequential detergent extraction...... and the transmembrane aminopeptidase N, whereas the peripheral lipid raft protein annexin 2 was essentially absent. In conclusion, in the microvillar membrane, galectin-4, functions as a core raft stabilizer/organizer for other, more loosely raft-associated proteins. The superraft analysis might be applicable to other...

  1. Development of organic membrane and biosensor. ; Artificial membrane chemical sensor on the model of olfactory cells. Seitaimaku to bio sensor no hatten. ; Kyusaibo wo model to shita jinkomaku kagaku sensor

    Energy Technology Data Exchange (ETDEWEB)

    Enomoto, S; Kashiwayanagi, M; Kurihara, K [Hokkaido University, Sapporo (Japan). Faculty of Pharmaceutical Science

    1991-05-05

    The olfactory cell is the most prominent chemical sensor to detect various kinds of external chemical substances with high sensibility. Consequently, on the model of such an organic chemical sensor mechanism, an artificial membrane with functions to detect and distinguish various chemical substances has been developed. In this study, a test using a lipid bimolecular membrane was carried out. As a result, it was found that the lipid bimolecular membrane showed membrane potential changes responding to various odorants. The mambrane with proper lipid composition presented almost the same sensibility to odorants as an olfactory organ. Response characteristic against various odors changed greatly due to the lipid composition and the addition of protein. It was also found that various odors can be discriminated by analyzing response information obtained from a lot of mambranes with different compositions Such ideas can be applied to the odor discrimination of the artificial membrane sensor. 14 refs., 13 figs.

  2. DNA damage, acetylcholinesterase activity and lysosomal stability in native and transplanted mussels (Mytilus edulis) in areas close to coastal chemical dumping sites in Denmark

    DEFF Research Database (Denmark)

    Rank, J.; Lehtonen, K. K.; Strand, J.

    2007-01-01

    of chemical pollution complex, as seen especially in the variability in results on DNA damage, and also in regard to AChE activity. These investigations further stress the importance of understanding the effects of natural factors (salinity, temperature, water levels, rain and storm events) in correct......Biomarkers of genotoxicity (DNA damage, measured as tail moment in the Comet assay), neurotoxicity (acetylcholinesterase inhibition, AChE) and general stress (lysosomal membrane stability, LMS) were studied in native and transplanted blue mussels (Mytilus edulis) in coastal areas of western Denmark...... potentially affected by anthropogenic pollution originating from chemical dumping sites. The results indicate responses to pollution in all the biomarkers applied at the suspected areas, but the results were not consistent. Seasonal fluctuations in exposure situations at the study sites make interpretation...

  3. Bcl-xL regulates mitochondrial energetics by stabilizing the inner membrane potential.

    Science.gov (United States)

    Chen, Ying-Bei; Aon, Miguel A; Hsu, Yi-Te; Soane, Lucian; Teng, Xinchen; McCaffery, J Michael; Cheng, Wen-Chih; Qi, Bing; Li, Hongmei; Alavian, Kambiz N; Dayhoff-Brannigan, Margaret; Zou, Shifa; Pineda, Fernando J; O'Rourke, Brian; Ko, Young H; Pedersen, Peter L; Kaczmarek, Leonard K; Jonas, Elizabeth A; Hardwick, J Marie

    2011-10-17

    Mammalian Bcl-x(L) protein localizes to the outer mitochondrial membrane, where it inhibits apoptosis by binding Bax and inhibiting Bax-induced outer membrane permeabilization. Contrary to expectation, we found by electron microscopy and biochemical approaches that endogenous Bcl-x(L) also localized to inner mitochondrial cristae. Two-photon microscopy of cultured neurons revealed large fluctuations in inner mitochondrial membrane potential when Bcl-x(L) was genetically deleted or pharmacologically inhibited, indicating increased total ion flux into and out of mitochondria. Computational, biochemical, and genetic evidence indicated that Bcl-x(L) reduces futile ion flux across the inner mitochondrial membrane to prevent a wasteful drain on cellular resources, thereby preventing an energetic crisis during stress. Given that F(1)F(O)-ATP synthase directly affects mitochondrial membrane potential and having identified the mitochondrial ATP synthase β subunit in a screen for Bcl-x(L)-binding partners, we tested and found that Bcl-x(L) failed to protect β subunit-deficient yeast. Thus, by bolstering mitochondrial energetic capacity, Bcl-x(L) may contribute importantly to cell survival independently of other Bcl-2 family proteins.

  4. Sol-gel route to synthesis of microporous ceramic membranes: Thermal stability of TiO2-ZrO2 mixed oxides

    International Nuclear Information System (INIS)

    Qunyin Xu; Anderson, M.A.

    1993-01-01

    In this paper concerning the synthesis of microporous ceramic membranes, the authors focus on the preparation and thermal stability of unsupported microporous TiO 2 -ZrO 2 mixed-oxide membranes. It has been observed that, by adding up to 20% ZrO 2 into TiO 2 or up to 10% TiO 2 into ZrO 2 , these microporous membranes display improved thermal stability. They can be fired up to 500 C for 0.5 h without closing micropores. However, membranes containing almost equal percentages of each component have lost microporous features and have low surface areas and low porosities. A phase diagram of a two-component TiO 2 -ZrO 2 mixed-oxide membrane has been prepared based on DTA and X-ray diffraction data in order to better understand the microstructure changes upon firing

  5. Evaluation of chemical stabilizers and windscreens for wind erosion control of uranium mill tailings

    International Nuclear Information System (INIS)

    Elmore, M.R.; Hartley, J.N.

    1984-08-01

    Potential wind erosion of uranium mill tailings is a concern for the surface disposal of tailings at uranium mills. Wind-blown tailings may subsequently be redeposited on areas outside the impoundment. Pacific Northwest Laboratory (PNL) is investigating techniques for fugitive dust control at uranium mill tailings piles. Laboratory tests, including wind tunnel studies, were conducted to evaluate the relative effectiveness of 43 chemical stabilizers. Seventeen of the more promising stabilizers were applied to test plots on a uranium tailings pile at the American Nuclear Corporation-Gas Hills Project mill site in central Wyoming. The durabilities of these materials under actual site conditions were evaluated over time. In addition, field testing of commercially available windscreens was conducted. Test panels were constructed of eight different materials at the Wyoming test site to compare their durability. A second test site was established near PNL to evaluate the effectiveness of windscreens at reducing wind velocity, and thereby reduce the potential for wind erosion of mill tailings. Results of the laboratory land field tests of the chemical stabilizers and windscreens are presented, along with costs versus effectiveness of these techniques for control of wind erosion at mill tailings piles. 12 references, 4 figures, 6 tables

  6. Study on thermal stability and chemical structure of polyamide blended with small amount of Cu

    International Nuclear Information System (INIS)

    Arai, Tsuyoshi; Ueno, Tomonaga; Kajiya, Takafumi; Ishikawa, Tomoyuki; Takeda, Kunihiko

    2007-01-01

    The thermal stability and the chemical structure of Polyamide 66 (PA66) blended with a small amount of copper have been studied. The thermal degradation of the blend with 35 ppm or more of copper was restrained and no strong influence of the concentration of copper was observed. The molecular weight of PA66 decreased by the thermal aging process but the amount of decrease of the blend was smaller than that of the non-blend. The water uptake of the blend increased. The chemical structure, which was observed by IR and NMR, changed slightly by blending with copper after aging at higher temperatures. Multiple items influenced the thermal stability of PA66 blended with a small amount of copper instead of just one. Namely, the main chain of PA66 is cut by heat and the degree of the cut is restrained by the copper. The diffusion time of copper atoms that disperse uniformly in the PA66 matrix is short enough to cover the individual amide groups and the effect enlarges the entire configuration of the PA66 chain to enhance the thermal stability. (author)

  7. Treatment of textile dyehouse effluent using ceramic membrane based process in combination with chemical pretreatment.

    Science.gov (United States)

    Bhattacharya, Priyankari; Ghosh, Sourja; Majumdar, Swachchha; Bandyopadhyay, Sibdas

    2013-10-01

    Treatment of highly concentrated dyebath effluent and comparatively dilute composite effluent having mixture of various reactive dyes collected from a cotton fabric dyeing unit was undertaken in the present study. Ceramic microfiltration membrane prepared from a cost effective composition of alumina and clay was used. Prior to microfiltration, a chemical pretreatment was carried out with aluminium sulphate in combination with a polymeric retention aid. An optimum dose of 100 mg/L of aluminium sulphate and 1 ml/L of a commercial flocculant Afilan RAMF was found effective for dye removal (> 98%) from the synthetic solutions of reactive dyes with initial concentration of 150 mg/L in both the single component and two component systems. In the microfiltration study, effect of operating pressure in the permeate flux was observed for both the pretreated and untreated effluents and permeate samples were analyzed for dye concentration, COD, turbidity, TSS, etc. during constant pressure filtration. About 98-99% removal of dyes was obtained in the combined process with COD reduction of 54-64%.

  8. Performance and Long-Term Stability of Pd/PSS and Pd/Al2O3 Membranes for Hydrogen Separation.

    Science.gov (United States)

    Liguori, Simona; Iulianelli, Adolfo; Dalena, Francesco; Pinacci, Pietro; Drago, Francesca; Broglia, Maria; Huang, Yan; Basile, Angelo

    2014-03-06

    The present work is focused on the investigation of the performance and long-term stability of two composite palladium membranes under different operating conditions. One membrane (Pd/porous stainless steel (PSS)) is characterized by a ~10 µm-thick palladium layer on a porous stainless steel substrate, which is pretreated by means of surface modification and oxidation; the other membrane (Pd/Al2O3) is constituted by a ~7 µm-thick palladium layer on an asymmetric microporous Al2O3 substrate. The operating temperature and pressure ranges, used for studying the performance of these two kinds of membranes, are 350-450 °C and 200-800 kPa, respectively. The H2 permeances and the H2/N2 selectivities of both membranes were investigated and compared with literature data. At 400 °C and 200 kPa as pressure difference, Pd/PSS and Pd/Al2O3 membranes exhibited an H2/N2 ideal selectivity equal to 11700 and 6200, respectively, showing stability for 600 h. Thereafter, H2/N2 selectivity of both membranes progressively decreased and after around 2000 h, dropped dramatically to 55 and 310 for the Pd/PSS and Pd/Al2O3 membranes, respectively. As evidenced by Scanning Electron Microscope (SEM) analyses, the pinholes appear on the whole surface of the Pd/PSS membrane and this is probably due to release of sulphur from the graphite seal rings.

  9. Deposition of yttria stabilized zirconia layer for solid oxide fuel cell by chemical vapor infiltration

    International Nuclear Information System (INIS)

    John, John T.; Dubey, Vivekanand; Kain, Vivekanand; Dey, Gautham Kumar; Prakash, Deep

    2011-01-01

    Free energy associated with a chemical reaction can be converted into electricity, if we can split the reaction into an anodic reaction and a cathodic reaction and carry out the reactions in an electrochemical cell using electrodes that will catalyze the reactions. We also have to use a suitable electrolyte, that serves to isolate the chemical species in the two compartments from getting mixed directly but allow an ion produced in one of the reactions to proceed to the other side and complete the reaction. For this reason cracks and porosity are not tolerated in the electrolyte. First generation solid oxide fuel cell (SOFC) uses yttria stabilized zirconia (YSZ) as the electrolyte. In spite of the fact that several solid electrolytes with higher conductivities at lower temperature are being investigated and developed, 8 mol% yttria stabilized zirconia (8YSZ) is considered to be the most favored electrolyte for the SOFC today. The electrolyte should be present as a thin, impervious layer of uniform thickness with good adherence, chemical and mechanical stability, in between the porous cathode and anode. Efforts to produce the 8YSZ coatings on porous lanthanum strontium manganite tubes by electrochemical vapor deposition (ECVD) have met with unexpected difficulties such as impurity pick up and chemical and mechanical instability of the LSM tubes in the ECVD environment. It was also difficult to keep the chemical composition of the YSZ coating at exactly 8 mol% Yttria in zirconia and to control the coating thickness in tight control. These problems were overcome by a two step deposition process where a YSZ layer of required thickness was produced by electrophoretic coating from an acetyl acetone bath at a voltage of 30-300V DC and sintered at 1300 deg C. The resulting porous YSZ layer was made impervious by chemical vapor infiltration (CVI) by the reaction between a mixture of vapors of YCl 3 and ZrCl 4 and steam at 1300 deg C as in the case of ECVD for a short

  10. A Pilot Chemical and Physical Stability Study of Extemporaneously Compounded Levetiracetam Intravenous Solution.

    Science.gov (United States)

    Raphael, Chenzira D; Zhao, Fang; Hughes, Susan E; Juba, Katherine M

    2015-01-01

    Levetiracetam is a commonly used antiepileptic medication for tumor-related epilepsy. However, the 100 mL intravenous (IV) infusion volume can be burdensome to imminently dying hospice patients. A reduced infusion volume would improve patient tolerability. The purpose of this study was to evaluate the stability of 1000 mg/25 mL (40 mg/mL) levetiracetam IV solution in sodium chloride 0.9%. We prepared levetiracetam 40 mg/mL IV solution and added it to polyvinyl chloride (PVC) bags, polyolefin bags, and polypropylene syringes. Triplicate samples of each product were stored at refrigeration (2-8°C) and analyzed on days 0, 1, 4, 7, and 14. Samples were subjected to visual inspection, pH measurement, and stability-indicating high-performance liquid chromatography (HPLC) analysis. Over the 2-week storage period, there was no significant change in visual appearance or pH for any of the stability samples. The HPLC results confirmed that all stability samples retained 94.2-101.3% of initial drug concentration and no degradation products or leachable material from the packaging materials were observed. We conclude that levetiracetam 1000 mg/25 mL IV solution in sodium chloride 0.9% is physically and chemically stable for up to 14 days under refrigeration in polypropylene syringes, PVC bags, and polyolefin bags.

  11. Micropore structure stabilization in organosilica membranes by gaseous catalyst post-treatment

    NARCIS (Netherlands)

    Dral, A. Petra; van Eck, Ernst R.H.; Winnubst, Louis; ten Elshof, Johan E.

    2018-01-01

    A post-treatment involving repeated exposure to gaseous HCl alternated with heating is demonstrated to strongly accelerate the recently reported structural evolution in organically bridged silica networks. Films, powders and membranes derived from 1,2-bis(triethoxysilyl)ethane were exposed to

  12. 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...

  13. Electrical conductivity and chemical stability of BaCe0· 8− xAxGd0 ...

    Indian Academy of Sciences (India)

    ... K. BaCe0.7In0.1Gd0.2O3− and BaCe0.7Zr0.1Gd0.2O3− ceramics exhibit an excellent chemical stability against boiling water. Indium is a suitable doping element to promote the sintering densification and to enhance both electrical conductivity and chemical stability of Gd-doped BaCeO3 at operating temperatures.

  14. Acquisition of Co metal from spent lithium-ion battery using emulsion liquid membrane technology and emulsion stability test

    Science.gov (United States)

    Yuliusman; Wulandari, P. T.; Amiliana, R. A.; Huda, M.; Kusumadewi, F. A.

    2018-03-01

    Lithium-ion batteries are the most common type to be used as energy source in mobile phone. The amount of lithium-ion battery wastes is approximated by 200 – 500 ton/year. In one lithium-ion battery, there are 5 – 20% of cobalt metal, depend on the manufacturer. One of the way to recover a valuable metal from waste is leaching process then continued with extraction, which is the aim of this study. Spent lithium-ion batteries will be characterized with EDX and AAS, the result will show the amount of cobalt metal with form of LiCoO2 in the cathode. Hydrochloric acid concentration used is 4 M, temperature 80°C, and reaction time 1 hour. This study will discuss the emulsion stability test on emulsion liquid membrane. The purpose of emulsion stability test in this study was to determine optimum concentration of surfactant and extractant to produce a stable emulsion. Surfactant and extractant used were SPAN 80 and Cyanex 272 respectively with both concentrations varied. Membrane and feed phase ratios used in this experiment was 1 : 2. The optimum results of this study were SPAN 80 concentrations of 10% w/v and Cyanex 272 0.7 M.

  15. Physical–chemical properties, separation performance, and fouling resistance of mixed-matrix ultrafiltration membranes

    KAUST Repository

    Hoek, Eric M.V.; Ghosh, Asim K.; Huang, Xiaofei; Liong, Monty; Zink, Jeffrey I.

    2011-01-01

    Herein we report on the formation and characterization of mixed-matrix ultrafiltration (UF) membranes hand-cast by nonsolvent induced phase inversion. We evaluated nanometer-to-micrometer sized inorganic fillers (silver, copper, silica, zeolite, and silver-zeolite) materials with polysulfone (PSf) as the polymeric dispersing matrix. In general, mixed-matrix membranes were rougher, more hydrophilic, and more mechanically robust. Only sub-micron zeolite-PSf mixed-matrix membranes exhibited simultaneous improvements in water permeability and solute selectivity; all other mixed-matrix membranes were more permeable, but less selective due to defects associated with poor polymer-filler binding. Protein and bacterial fouling resistance of mixed-matrix membranes containing silver, zeolite, and silver-zeolite nanoparticles were compared to a low-fouling, poly(acrylonitrile) (PAN) UF membrane. Zeolite and silver containing membranes exhibited better protein fouling resistance (due to higher hydrophilicity), whereas silver and silver-zeolite based membranes produce better bacterial fouling resistance due to antimicrobial properties. Overall, zeolite-PSf and silver exchanged zeolite-PSf membranes offered the best combination of improved permeability, selectivity, and fouling resistance - superior to the commercial PAN membrane. © 2011 Elsevier B.V.

  16. Physical–chemical properties, separation performance, and fouling resistance of mixed-matrix ultrafiltration membranes

    KAUST Repository

    Hoek, Eric M.V.

    2011-12-01

    Herein we report on the formation and characterization of mixed-matrix ultrafiltration (UF) membranes hand-cast by nonsolvent induced phase inversion. We evaluated nanometer-to-micrometer sized inorganic fillers (silver, copper, silica, zeolite, and silver-zeolite) materials with polysulfone (PSf) as the polymeric dispersing matrix. In general, mixed-matrix membranes were rougher, more hydrophilic, and more mechanically robust. Only sub-micron zeolite-PSf mixed-matrix membranes exhibited simultaneous improvements in water permeability and solute selectivity; all other mixed-matrix membranes were more permeable, but less selective due to defects associated with poor polymer-filler binding. Protein and bacterial fouling resistance of mixed-matrix membranes containing silver, zeolite, and silver-zeolite nanoparticles were compared to a low-fouling, poly(acrylonitrile) (PAN) UF membrane. Zeolite and silver containing membranes exhibited better protein fouling resistance (due to higher hydrophilicity), whereas silver and silver-zeolite based membranes produce better bacterial fouling resistance due to antimicrobial properties. Overall, zeolite-PSf and silver exchanged zeolite-PSf membranes offered the best combination of improved permeability, selectivity, and fouling resistance - superior to the commercial PAN membrane. © 2011 Elsevier B.V.

  17. Chemical and enzymatic stability of amino acid prodrugs containing methoxy, ethoxy and propylene glycol linkers.

    Science.gov (United States)

    Gupta, Deepak; Gupta, Sheeba Varghese; Lee, Kyung-Dall; Amidon, Gordon L

    2009-01-01

    We evaluated the chemical and enzymatic stabilities of prodrugs containing methoxy, ethoxy and propylene glycol linkers in order to find a suitable linker for prodrugs of carboxylic acids with amino acids. l-Valine and l-phenylalanine prodrugs of model compounds (benzoic acid and phenyl acetic acid) containing methoxy, ethoxy and propylene glycol linkers were synthesized. The hydrolysis rate profile of each compound was studied at physiologically relevant pHs (1.2, 4, 6 and 7.4). Enzymatic hydrolysis of propylene glycol containing compounds was studied using Caco-2 homogenate as well as purified enzyme valacyclovirase. It was observed that the stability of the prodrugs increases with the linker length (propyl > ethyl > methyl). The model prodrugs were stable at acidic pH as compared to basic pH. It was observed that the prodrug with the aliphatic amino acid promoiety was more stable compared to its aromatic counterpart. The comparison between benzyl and the phenyl model compounds revealed that the amino acid side chain is significant in determining the stability of the prodrug whereas the benzyl or phenyl carboxylic acid had little or no effect on the stability. The enzymatic activation studies of propylene glycol linker prodrug in the presence of valacyclovirase and cell homogenate showed faster generation of the parent drug at pH 7.4. The half-life of prodrugs at pH 7.4 was more than 12 h, whereas in the presence of cell homogenate the half-lives were less than 1 h. Hydrolysis by Caco-2 homogenate generated the parent compound in two steps, where the prodrug was first converted to the intermediate, propylene glycol benzoate, which was then converted to the parent compound (benzoic acid). Enzymatic hydrolysis of propylene glycol containing prodrugs by valacyclovirase showed hydrolysis of the amino acid ester part to generate the propylene glycol ester of model compound (propylene glycol benzoate) as the major product. The amino acid prodrugs containing methoxy

  18. The chemical stability of TRISO-coated HTGR fuel. Pt. 1. Status report

    International Nuclear Information System (INIS)

    Groot, P.; Cordfunke, E.H.P.; Konings, R.J.M.

    1994-12-01

    The US fuel seemed to be more difficult to produce than the German fuel. Also the chemical stability of this fuel must be investigated. The conditions are more severe in the US concept than in the German concept. Oxidation of the graphite seems to be no problem, according to US HTGR concept. A ZrC coating seems to have a number of advantages with regard to the SiC coating: (1) Better retention, (2) no reaction with Pd, (3) no thermal dissociation. Only the oxidation resistance is worse than SiC. Also the maximum stress must be determined that the ZrC coating can have. (orig./HP)

  19. Assessment of soil stabilization by chemical extraction and bioaccumulation using earthworm, Eisenia fetida

    Science.gov (United States)

    Lee, Byung-Tae; Abd Aziz, Azilah; Han, Heop Jo; Kim, Kyoung-Woong

    2014-05-01

    Soil stabilization does not remove heavy metals from contaminated soil, but lowers their exposures to ecosystem. Thus, it should be evaluated by measuring the fractions of heavy metals which are mobile and/or bioavailable in soils. The study compared several chemical extractions which intended to quantify the mobile or bioaccessible fractions with uptake and bioaccumulation by earthworm, Eisenia fetida. Soil samples were taken from the abandoned mine area contaminated with As, Cd, Cu, Pb and/or Zn. To stabilize heavy metals, the soils were amended with limestone and steel slag at 5% and 2% (w/w), respectively. All chemical extractions and earthworm tests were applied to both the contaminated and the stabilized soils with triplicates. The chemical extractions consisted of six single extractions which were 0.01M CaCl2 (unbufferred), EDTA or DTPA (chelating), TCLP (acidic), Mehlich 3 (mixture), and aqua regia (peudo-total). Sequential extractions were also applied to fractionate heavy metals in soils. In earthworm tests, worms were exposed to the soils for uptake of heavy metals. After 28 days of exposure to soils, worms were transferred to clean soils for elimination. During the tests, three worms were randomly collected at proper sampling events. Worms were rinsed with DI water and placed on moist filter paper for 48 h for depuration. Filter paper was renewed at 24 h to prevent coprophagy. The worms were killed with liquid nitrogen, dried in the oven, and digested with aqua regia for ICP-MS analysis. In addition to the bioaccumulation, several toxicity endpoints were observed such as burrowing time, mortality, cocoon production, and body weight changes. Toxicokinetics was applied to determine the uptake and elimination heavy metals by the earthworms. Bioaccumulation factor (BAF) was estimated using total metal concentrations and body burdens. Pearson correlation and simple linear regression were applied to evaluate the relationship between metal fractions by single

  20. Chemical stability and defect formation in CaHfO3

    KAUST Repository

    Alay-E-Abbas, Syed Muhammad

    2014-04-01

    Defects in CaHfO3 are investigated by ab initio calculations based on density functional theory. Pristine and anion-deficient CaHfO 3 are found to be insulating, whereas cation-deficient CaHfO 3 is hole-doped. The formation energies of neutral and charged cation and anion vacancies are evaluated to determine the stability in different chemical environments. Moreover, the energies of the partial and full Schottky defect reactions are computed. We show that clustering of anion vacancies in the HfO layers is energetically favorable for sufficiently high defect concentrations and results in metallicity. © 2014 EPLA.

  1. Chemical stability and defect formation in CaHfO3

    KAUST Repository

    Alay-E-Abbas, Syed Muhammad; Nazir, Safdar; Mun Wong, Kin; Shaukat, Ali; Schwingenschlö gl, Udo

    2014-01-01

    Defects in CaHfO3 are investigated by ab initio calculations based on density functional theory. Pristine and anion-deficient CaHfO 3 are found to be insulating, whereas cation-deficient CaHfO 3 is hole-doped. The formation energies of neutral and charged cation and anion vacancies are evaluated to determine the stability in different chemical environments. Moreover, the energies of the partial and full Schottky defect reactions are computed. We show that clustering of anion vacancies in the HfO layers is energetically favorable for sufficiently high defect concentrations and results in metallicity. © 2014 EPLA.

  2. Physico-chemical stability of eribulin mesylate containing concentrate and ready-to-administer solutions.

    Science.gov (United States)

    Spindeldreier, Kirsten; Thiesen, Judith; Lipp, Hans-Peter; Krämer, Irene

    2014-06-01

    The aim of this study was to determine the stability of commercially available eribulin mesylate containing injection solution as well as diluted ready-to-administer solutions stored under refrigeration or at room temperature. Stability was studied by a novel developed stability-indicating reversed-phase high-performance liquid chromatography (RP-HPLC) assay with ultraviolet detection (detection wavelength 200 nm). Triplicate test solutions of eribulin mesylate containing injection concentrate (0.5 mg/mL) and with 0.9% sodium chloride solution diluted ready-to-administer preparations (0.205 mg/mL eribulin mesylate in polypropylene (PP) syringes, 0.020 mg/mL eribulin mesylate in polypropylene/polyethylene (PE) bags) were stored protected from light either at room temperature (25) or under refrigeration (2-8). Samples were withdrawn on day 0 (initial), 1, 3, 5, 7, 14, 21 and 28 of storage and assayed. Physical stability was determined by measuring the pH value once a week and checking for visible precipitations or colour changes. The stability tests revealed that concentrations of eribulin mesylate remained unchanged over a period of 28 days irrespective of concentration, container material or storage temperature. Neither colour changes nor visible particles have been observed. The pH value varied slightly over time but remained in the stability favourable range of 5-9. Eribulin mesylate injection (0.5 mg/mL) is physico-chemically stable over a period of 28 days after first puncture of the vial. After dilution with 0.9% NaCl vehicle solution, ready-to-administer eribulin mesylate injection solutions (0.205 mg/mL in PP syringe) and infusion solutions (0.02 mg/mL in prefilled PP/PE bags) are physico-chemically stable for a period of at least four weeks either refrigerated or stored at room temperature. For microbiological reasons storage under refrigeration is recommended.

  3. Membrane alterations following toxic chemical insult. Research progress report No. 3 (Final), 15 July 1984-31 January 1988

    Energy Technology Data Exchange (ETDEWEB)

    Liss, A.

    1988-03-10

    A procaryotic cell system was developed that can be used to determine the toxic action of chemicals acting at the level of the eucaryotic or procaryotic cytoplasmic membrane. Cell wall-less microbes known as mycoplasmas were used. In this current study, two perfluorinated fatty acids (CB and C10) were found to inhibit the growth of the test mycoplasmas. Two apparent activities, cytotoxicity and cytolysis, were observed. At high concentrations (>10 mM), a detergent-like action was noted. At low concentrations (<10 mM), cell death was observed without detectable cell lysis. Altering the cell membrane (the presumed target of the toxic compounds) resulted in altered levels to toxicity. Similar results were obtained when human or murine B-cells were used as the target organism. The toxic action of the perfluorinated fatty acids apparently involves some interaction with the membrane of the cells being treated.

  4. Effects of anticaking agents and relative humidity on the physical and chemical stability of powdered vitamin C.

    Science.gov (United States)

    Lipasek, Rebecca A; Taylor, Lynne S; Mauer, Lisa J

    2011-09-01

    Vitamin C is an essential nutrient that is widely used by the food industry in the powder form for both its nutritional and functional properties. However, vitamin C is deliquescent, and deliquescence has been linked to physical and chemical instabilities. Anticaking agents are often added to powder systems to delay or prevent caking, but little is known about their effect on the chemical stability of powders. In this study, various anticaking agents (calcium phosphate, calcium silicate, calcium stearate, corn starch, and silicon dioxide) were combined with sodium ascorbate at 2% and 50% w/w ratios and stored at various relative humidities (23%, 43%, 64%, 75%, 85%, and 98% RHs). Chemical and physical stability and moisture sorption were monitored over time. Additionally, saturated solution samples were stored at various pHs to determine the effect of surface pH and dissolution on the vitamin degradation rate. Storage RH, time, and anticaking agent type and ratio all significantly affected (P vitamin C stability. Silicon dioxide and calcium silicate (50% w/w) and calcium stearate (at both ratios) were the only anticaking agents to improve the physical stability of powdered sodium ascorbate while none of the anticaking agents improved its chemical stability. However, corn starch and calcium stearate had the least adverse effect on chemical stability. Dissolution rate and pH were also important factors affecting the chemical and physical stability of the powders. Therefore, monitoring storage environmental conditions and anticaking agent usage are important for understanding the stability of vitamin C. Anticaking agent type and ratio significantly affected the physical and chemical stability of vitamin C over time and over a range of RHs. No anticaking agent improved the chemical stability of the vitamin, and most caused an increase in chemical degradation even if physical stability was improved. It is possible that anticaking agents would greatly affect other

  5. Environmental impact of industrial sludge stabilization/solidification products: chemical or ecotoxicological hazard evaluation?

    Science.gov (United States)

    Silva, Marcos A R; Testolin, Renan C; Godinho-Castro, Alcione P; Corrêa, Albertina X R; Radetski, Claudemir M

    2011-09-15

    Nowadays, the classification of industrial solid wastes is not based on risk analysis, thus the aim of this study was to compare the toxicity classifications based on the chemical and ecotoxicological characterization of four industrial sludges submitted to a two-step stabilization/solidification (S/S) processes. To classify S/S products as hazardous or non-hazardous, values cited in Brazilian chemical waste regulations were adopted and compared to the results obtained with a battery of biotests (bacteria, alga and daphnids) which were carried out with soluble and leaching fractions. In some cases the hazardous potential of industrial sludge was underestimated, since the S/S products obtained from the metal-mechanics and automotive sludges were chemically classified as non-hazardous (but non-inert) when the ecotoxicity tests showed toxicity values for leaching and soluble fractions. In other cases, the environmental impact was overestimated, since the S/S products of the textile sludges were chemically classified as non-inert (but non-hazardous) while ecotoxicity tests did not reveal any effects on bacteria, daphnids and algae. From the results of the chemical and ecotoxicological analyses we concluded that: (i) current regulations related to solid waste classification based on leachability and solubility tests do not ensure reliable results with respect to environmental protection; (ii) the two-step process was very effective in terms of metal immobilization, even at higher metal-concentrations. Considering that S/S products will be subject to environmental conditions, it is of great interest to test the ecotoxicity potential of the contaminants release from these products with a view to avoiding environmental impact given the unreliability of ecotoxicological estimations originating from chemical analysis. Copyright © 2011 Elsevier B.V. All rights reserved.

  6. An investigation on the chemical stability and a novel strategy for long-term stabilization of diphenylalanine nanostructures in aqueous solution

    Directory of Open Access Journals (Sweden)

    H. Nezammahalleh

    2015-01-01

    Full Text Available The stability of diphenylalanine (FF microwires and microtubes in phosphate buffer solution was investigated and a novel strategy was developed for their chemical stabilization. This stability investigation was carried out by optical microscopy and by high performance liquid chromatography (HPLC. These microstructures dissolve in the solution depending upon their degree of FF saturation. The dissolution mechanisms of the structures in kinetically limited processes were found by accurately fitting the experimental dissolution data to a theoretical kinetic equation. The dissolution data were well fitted to the particular Avrami-Erofe’ev kinetic expression (R2 > 0.98. These findings suggest that the structures can be stabilized by a decrease in the hydration of the constituent molecules thorough a chemical conformational induced transition upon heat treatment. The stable microtubes were fabricated in a novel three step procedure consisting of the reduction of silver ions in unstable FF microtubes by a citrate reductant, the stabilization by chemical conformational induced transition upon heat treatment, and the consequent oxidation of the reduced silver by a persulfate oxidant. These materials were characterized by electron microscopy and powder X-ray diffraction techniques. The long-term stability of both structures was also confirmed by optical microscopy and HPLC.

  7. Modification of Nafion Membranes by IL-Cation Exchange: Chemical Surface, Electrical and Interfacial Study

    Directory of Open Access Journals (Sweden)

    V. Romero

    2012-01-01

    A study of time evolution of the impedance curves measured in the system “IL aqueous solution/Nafion-112 membrane/IL aqueous solution” was also performed. This study allows us monitoring the electrical changes associated to the IL-cation incorporation in both the membrane and the membrane/IL solution interface, and it provides supplementary information on the characteristic of the Nafion/DTA+ hybrid material. Moreover, the results also show the significant effect of water on the electrical resistance of the Nafion-112/IL-cation-modified membrane.

  8. Involvement of the Cdc42 pathway in CFTR post-translational turnover and in its plasma membrane stability in airway epithelial cells.

    Directory of Open Access Journals (Sweden)

    Romain Ferru-Clément

    Full Text Available Cystic fibrosis transmembrane conductance regulator (CFTR is a chloride channel that is expressed on the apical plasma membrane (PM of epithelial cells. The most common deleterious allele encodes a trafficking-defective mutant protein undergoing endoplasmic reticulum-associated degradation (ERAD and presenting lower PM stability. In this study, we investigated the involvement of the Cdc42 pathway in CFTR turnover and trafficking in a human bronchiolar epithelial cell line (CFBE41o- expressing wild-type CFTR. Cdc42 is a small GTPase of the Rho family that fulfils numerous cell functions, one of which is endocytosis and recycling process via actin cytoskeleton remodelling. When we treated cells with chemical inhibitors such as ML141 against Cdc42 and wiskostatin against the downstream effector N-WASP, we observed that CFTR channel activity was inhibited, in correlation with a decrease in CFTR amount at the cell surface and an increase in dynamin-dependent CFTR endocytosis. Anchoring of CFTR to the cortical cytoskeleton was then presumably impaired by actin disorganization. When we performed siRNA-mediated depletion of Cdc42, actin polymerization was not impacted, but we observed actin-independent consequences upon CFTR. Total and PM CFTR amounts were increased, resulting in greater activation of CFTR. Pulse-chase experiments showed that while CFTR degradation was slowed, CFTR maturation through the Golgi apparatus remained unaffected. In addition, we observed increased stability of CFTR in PM and reduction of its endocytosis. This study highlights the involvement of the Cdc42 pathway at several levels of CFTR biogenesis and trafficking: (i Cdc42 is implicated in the first steps of CFTR biosynthesis and processing; (ii it contributes to the stability of CFTR in PM via its anchoring to cortical actin; (iii it promotes CFTR endocytosis and presumably its sorting toward lysosomal degradation.

  9. Maltose-neopentyl glycol (MNG) amphiphiles for solubilization, stabilization and crystallization of membrane proteins

    OpenAIRE

    Chae, Pil Seok; Rasmussen, Søren G. F.; Rana, Rohini; Gotfryd, Kamil; Chandra, Richa; Goren, Michael A.; Kruse, Andrew C.; Nurva, Shailika; Loland, Claus J.; Pierre, Yves; Drew, David; Popot, Jean-Luc; Picot, Daniel; Fox, Brian G.; Guan, Lan

    2010-01-01

    The understanding of integral membrane protein (IMP) structure and function is hampered by the difficulty of handling these proteins. Aqueous solubilization, necessary for many types of biophysical analysis, generally requires a detergent to shield the large lipophilic surfaces displayed by native IMPs. Many proteins remain difficult to study owing to a lack of suitable detergents. We introduce a class of amphiphiles, each of which is built around a central quaternary carbon atom derived from...

  10. Molecularly Designed Stabilized Asymmetric Hollow Fiber Membranes for Aggressive Natural Gas Separation.

    Science.gov (United States)

    Liu, Gongping; Li, Nanwen; Miller, Stephen J; Kim, Danny; Yi, Shouliang; Labreche, Ying; Koros, William J

    2016-10-24

    New rigid polyimides with bulky CF 3 groups were synthesized and engineered into high-performance hollow fiber membranes. The enhanced rotational barrier provided by properly positioned CF 3 side groups prohibited fiber transition layer collapse during cross-linking, thereby greatly improving CO 2 /CH 4 separation performance compared to conventional materials for aggressive natural gas feeds. © 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  11. Stabilization of mitochondrial membrane potential prevents doxorubicin-induced cardiotoxicity in isolated rat heart

    International Nuclear Information System (INIS)

    Montaigne, David; Marechal, Xavier; Baccouch, Riadh; Modine, Thomas; Preau, Sebastien; Zannis, Konstantinos; Marchetti, Philippe; Lancel, Steve; Neviere, Remi

    2010-01-01

    The present study was undertaken to examine the effects of doxorubicin on left ventricular function and cellular energy state in intact isolated hearts, and, to test whether inhibition of mitochondrial membrane potential dissipation would prevent doxorubicin-induced mitochondrial and myocardial dysfunction. Myocardial contractile performance and mitochondrial respiration were evaluated by left ventricular tension and its first derivatives and cardiac fiber respirometry, respectively. NADH levels, mitochondrial membrane potential and glucose uptake were monitored non-invasively via epicardial imaging of the left ventricular wall of Langendorff-perfused rat hearts. Heart performance was reduced in a time-dependent manner in isolated rat hearts perfused with Krebs-Henseleit solution containing 1 μM doxorubicin. Compared with controls, doxorubicin induced acute myocardial dysfunction (dF/dt max of 105 ± 8 mN/s in control hearts vs. 49 ± 7 mN/s in doxorubicin-treated hearts; *p < 0.05). In cardiac fibers prepared from perfused hearts, doxorubicin induced depression of mitochondrial respiration (respiratory control ratio of 4.0 ± 0.2 in control hearts vs. 2.2 ± 0.2 in doxorubicin-treated hearts; *p < 0.05) and cytochrome c oxidase kinetic activity (24 ± 1 μM cytochrome c/min/mg in control hearts vs. 14 ± 3 μM cytochrome c/min/mg in doxorubicin-treated hearts; *p < 0.05). Acute cardiotoxicity induced by doxorubicin was accompanied by NADH redox state, mitochondrial membrane potential, and glucose uptake reduction. Inhibition of mitochondrial permeability transition pore opening by cyclosporine A largely prevented mitochondrial membrane potential dissipation, cardiac energy state and dysfunction. These results suggest that in intact hearts an impairment of mitochondrial metabolism is involved in the development of doxorubicin cardiotoxicity.

  12. A study of chemical modifications of a Nafion membrane by incorporation of different room temperature ionic liquids

    Energy Technology Data Exchange (ETDEWEB)

    Martinez de Yuso, M.V.; Rodriguez-Castellon, E. [Departamento de Quimica Inorganica, Facultad de Ciencias, Universidad de Malaga (Spain); Neves, L.A.; Coelhoso, I.M.; Crespo, J.G. [REQUIMTE/CQFB, Departamento de Quimica, Universidade Nova de Lisboa, Caparica (Portugal); Benavente, J. [Departamento de Fisica Aplicada I, Facultad de Ciencias, Universidad de Malaga (Spain)

    2012-08-15

    Surface and bulk chemical changes in a Nafion membrane as a result of room temperature ionic liquids (RTILs) incorporation were determined by X-ray photoelectron spectroscopy (XPS) and elemental analysis, respectively. RTILs with different physicochemical properties were selected. Two imidazolium based RTIL-cations (1-octyl-3-methylimidazolium and 1-butyl-3-methylimidazolium) were used to detect the effect of cation size on membrane modification, while the effect of the RTIL hydrophilic/hydrophobic character was also considered by choosing different anions. Angle resolved XPS measurements (ARXPS) were carried out varying the angle of analysis between 15 and 75 to get elemental information on the Nafion/RTIL-modified membranes interactions for a deepness of around 10 nm. Moreover, changes in the RTIL-modified membranes associated to thermal effect were also considered by analyzing the samples after their heating at 120 C for 24 h. Agreement between both chemical techniques, bulk and destructive elemental analysis and surface and non-destructive XPS, were obtained. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  13. A high stability Ni-La0.5Ce0.5O2-δ asymmetrical metal-ceramic membrane for hydrogen separation and generation

    Science.gov (United States)

    Zhu, Zhiwen; Sun, Wenping; Wang, Zhongtao; Cao, Jiafeng; Dong, Yingchao; Liu, Wei

    2015-05-01

    In this work, hydrogen permeation properties of Ni-La0.5Ce0.5O2-δ (LDC) asymmetrical cermet membrane are investigated, including hydrogen fluxes (JH2) under different hydrogen partial pressures, the influence of water vapor on JH2 and the long-term stability of the membrane operating under the containing-CO2 atmosphere. Ni-LDC asymmetrical membrane shows the best hydrogen permeability among LDC-based hydrogen separation membranes, inferior to Ni-BaZr0.1Ce0.7Y0.2O3-δ asymmetrical membrane. The water vapor in feed gas is beneficial to hydrogen transport process, which promote an increase of JH2 from 5.64 × 10-8 to 6.83 × 10-8 mol cm-2 s-1 at 900 °C. Stability testing of hydrogen permeation suggests that Ni-LDC membrane remains stable against CO2. A dual function of combining hydrogen separation and generation can be realized by humidifying the sweep gas and enhance the hydrogen output by 1.0-1.5 times. Ni-LDC membrane exhibits desirable performance and durability in dual-function mode. Morphologies and phase structures of the membrane after tests are also characterized by SEM and XRD.

  14. Organosilica Membrane with Ionic Liquid Properties for Separation of Toluene/H₂ Mixture.

    Science.gov (United States)

    Hirota, Yuichiro; Maeda, Yohei; Yamamoto, Yusuke; Miyamoto, Manabu; Nishiyama, Norikazu

    2017-08-03

    In this study, we present a new concept in chemically stabilized ionic liquid membranes: an ionic liquid organosilica (ILOS) membrane, which is an organosilica membrane with ionic liquid-like properties. A silylated ionic liquid was used as a precursor for synthesis. The permselectivity, permeation mechanism, and stability of the membrane in the H₂/toluene binary system were then compared with a supported ionic liquid membrane. The membrane showed a superior separation factor of toluene/H₂ (>17,000) in a binary mixture system based on a solution-diffusion mechanism with improved durability over the supported ionic liquid membrane.

  15. Chemical quality and oxidative stability of extra virgin olive oils from San Juan province (Argentina).

    Science.gov (United States)

    Ceci, Liliana N; Mattar, Susana B; Carelli, Amalia A

    2017-10-01

    This study provides information about the chemical quality (quality indices, fatty acid profile, total polyphenols (PPs), tocopherols and pigments) and oxidative stability index (OSI) of virgin olive oils of Arbequina, Changlot Real and Coratina cultivars (San Juan province, Argentina). The influence of the cultivar and the effect of earlier harvest dates on the yields (OY), quality and OSI of the oils were also evaluated. All the oils were classified as extra virgin. The OY (L/100kg) averaged: Arbequina=13.2, Changlot Real=21.3, Coratina=18.3. The oleic acid (O) percentage, oleic to linoleic plus linolenic ratio [O/(L+Ln)], PPs and OSI were highly dependent on cultivar (Arbequinachemical and nutritional quality, higher oxidative stability and a fatty acid profile according to the IOC trade standard. Copyright © 2017 Elsevier Ltd. All rights reserved.

  16. Preparation and chemical stability of iron-nitride-coated iron microparticles

    International Nuclear Information System (INIS)

    Luo Xin; Liu Shixiong

    2007-01-01

    Iron-nitride-coated iron microparticles were prepared by nitridation of the surface of iron microparticles with ammonia gas at a temperature of 510 deg. C. The phases, composition, morphology, magnetic properties, and chemical stability of the particles were studied. The phases were α-Fe, ε-Fe 3 N, and γ-Fe 4 N. The composition varied from the core to the surface, with 99.8 wt% Fe in the core, and 93.8 wt% Fe and 6 wt% N in the iron-nitride coating. The thickness of the iron-nitride coating was about 0.28 μm. The chemical stability of the microparticles was greatly improved, especially the corrosion resistance in corrosive aqueous media. The saturation magnetization and the coercive force were 17.1x10 3 and 68 kA/m, respectively. It can be concluded that iron-nitride-coated iron microparticles will be very useful in many fields, such as water-based magnetorheological fluids and polishing fluids

  17. Unique battery with an active membrane separator having uniform physico-chemically functionalized ion channels and a method making the same

    Science.gov (United States)

    Gerald, II, Rex E.; Ruscic, Katarina J [Chicago, IL; Sears, Devin N [Spruce Grove, CA; Smith, Luis J [Natick, MA; Klingler, Robert J [Glenview, IL; Rathke, Jerome W [Homer Glen, IL

    2012-02-21

    The invention relates to a unique battery having an active, porous membrane and method of making the same. More specifically the invention relates to a sealed battery system having a porous, metal oxide membrane with uniform, physicochemically functionalized ion channels capable of adjustable ionic interaction. The physicochemically-active porous membrane purports dual functions: an electronic insulator (separator) and a unidirectional ion-transporter (electrolyte). The electrochemical cell membrane is activated for the transport of ions by contiguous ion coordination sites on the interior two-dimensional surfaces of the trans-membrane unidirectional pores. The membrane material is designed to have physicochemical interaction with ions. Control of the extent of the interactions between the ions and the interior pore walls of the membrane and other materials, chemicals, or structures contained within the pores provides adjustability of the ionic conductivity of the membrane.

  18. OXYGEN TRANSPORT CERAMIC MEMBRANES

    Energy Technology Data Exchange (ETDEWEB)

    Dr. Sukumar Bandopadhyay; Dr. Nagendra Nagabhushana

    2000-10-01

    This is the third quarterly report on oxygen Transport Ceramic Membranes. In the following, the report describes the progress made by our university partners in Tasks 1 through 6, experimental apparatus that was designed and built for various tasks of this project, thermodynamic calculations, where applicable and work planned for the future. (Task 1) Design, fabricate and evaluate ceramic to metal seals based on graded ceramic powder/metal braze joints. (Task 2) Evaluate the effect of defect configuration on ceramic membrane conductivity and long term chemical and structural stability. (Task 3) Determine materials mechanical properties under conditions of high temperatures and reactive atmospheres. (Task 4) Evaluate phase stability and thermal expansion of candidate perovskite membranes and develop techniques to support these materials on porous metal structures. (Task 5) Assess the microstructure of membrane materials to evaluate the effects of vacancy-impurity association, defect clusters, and vacancy-dopant association on the membrane performance and stability. (Task 6) Measure kinetics of oxygen uptake and transport in ceramic membrane materials under commercially relevant conditions using isotope labeling techniques.

  19. Profiling of the Tox21 Chemical Collection for Mitochondrial Function to Identify Compounds that Acutely Decrease Mitochondrial Membrane Potential

    Science.gov (United States)

    Attene-Ramos, Matias S.; Huang, Ruili; Michael, Sam; Witt, Kristine L.; Richard, Ann; Tice, Raymond R.; Simeonov, Anton; Austin, Christopher P.

    2014-01-01

    Background: Mitochondrial dysfunction has been implicated in the pathogenesis of a variety of disorders including cancer, diabetes, and neurodegenerative and cardiovascular diseases. Understanding whether different environmental chemicals and druglike molecules impact mitochondrial function represents an initial step in predicting exposure-related toxicity and defining a possible role for such compounds in the onset of various diseases. Objectives: We sought to identify individual chemicals and general structural features associated with changes in mitochondrial membrane potential (MMP). Methods: We used a multiplexed [two end points in one screen; MMP and adenosine triphosphate (ATP) content] quantitative high throughput screening (qHTS) approach combined with informatics tools to screen the Tox21 library of 10,000 compounds (~ 8,300 unique chemicals) at 15 concentrations each in triplicate to identify chemicals and structural features that are associated with changes in MMP in HepG2 cells. Results: Approximately 11% of the compounds (913 unique compounds) decreased MMP after 1 hr of treatment without affecting cell viability (ATP content). In addition, 309 compounds decreased MMP over a concentration range that also produced measurable cytotoxicity [half maximal inhibitory concentration (IC50) in MMP assay/IC50 in viability assay ≤ 3; p Tice RR, Simeonov A, Austin CP, Xia M. 2015. Profiling of the Tox21 chemical collection for mitochondrial function to identify compounds that acutely decrease mitochondrial membrane potential. Environ Health Perspect 123:49–56; http://dx.doi.org/10.1289/ehp.1408642 PMID:25302578

  20. Stability of Dry Probiotic Bacteria in Relation to the Cellular Membrane and Genomic DNA

    DEFF Research Database (Denmark)

    Hansen, Marie-Louise Rittermann W

    powders to infant formula and functional foods, e.g. cereal and chocolate bars. Part of production of the probiotic product often includes freeze-drying of the probiotic bacteria. Drying is necessary in the preparation of dry powders, and to increase shelf life of the product at ambient temperatures....... Freeze-drying and storage of probiotic bacteria can, however, also have a negative effect on cell stability. It is important to understand the processes, which can lead to loss of cell stability during dry storage in order to develop more stable probiotic products. The purpose of the present PhD thesis...

  1. Organic Redox Species in Aqueous Flow Batteries: Redox Potentials, Chemical Stability and Solubility

    Science.gov (United States)

    Wedege, Kristina; Dražević, Emil; Konya, Denes; Bentien, Anders

    2016-01-01

    Organic molecules are currently investigated as redox species for aqueous low-cost redox flow batteries (RFBs). The envisioned features of using organic redox species are low cost and increased flexibility with respect to tailoring redox potential and solubility from molecular engineering of side groups on the organic redox-active species. In this paper 33, mainly quinone-based, compounds are studied experimentially in terms of pH dependent redox potential, solubility and stability, combined with single cell battery RFB tests on selected redox pairs. Data shows that both the solubility and redox potential are determined by the position of the side groups and only to a small extent by the number of side groups. Additionally, the chemical stability and possible degradation mechanisms leading to capacity loss over time are discussed. The main challenge for the development of all-organic RFBs is to identify a redox pair for the positive side with sufficiently high stability and redox potential that enables battery cell potentials above 1 V. PMID:27966605

  2. Organic Redox Species in Aqueous Flow Batteries: Redox Potentials, Chemical Stability and Solubility

    Science.gov (United States)

    Wedege, Kristina; Dražević, Emil; Konya, Denes; Bentien, Anders

    2016-12-01

    Organic molecules are currently investigated as redox species for aqueous low-cost redox flow batteries (RFBs). The envisioned features of using organic redox species are low cost and increased flexibility with respect to tailoring redox potential and solubility from molecular engineering of side groups on the organic redox-active species. In this paper 33, mainly quinone-based, compounds are studied experimentially in terms of pH dependent redox potential, solubility and stability, combined with single cell battery RFB tests on selected redox pairs. Data shows that both the solubility and redox potential are determined by the position of the side groups and only to a small extent by the number of side groups. Additionally, the chemical stability and possible degradation mechanisms leading to capacity loss over time are discussed. The main challenge for the development of all-organic RFBs is to identify a redox pair for the positive side with sufficiently high stability and redox potential that enables battery cell potentials above 1 V.

  3. Modulation of erythrocyte membrane mechanical stability by 2,3-diphosphoglycerate in the neonatal poikilocytosis/elliptocytosis syndrome.

    Science.gov (United States)

    Mentzer, W C; Iarocci, T A; Mohandas, N; Lane, P A; Smith, B; Lazerson, J; Hays, T

    1987-01-01

    To explain the transient anemia and poikilocytosis seen during infancy in hereditary elliptocytosis (HE), we resealed erythrocyte (RBC) ghosts from affected children or their elliptocytic parents with 2,3-diphosphoglycerate (DPG) (0-8 mM), a compound that dissociates membrane skeletons, then measured ghost mechanical stability in the ektacytometer. Without added 2,3-DPG, ghost mechanical stability was subnormal in infantile poikilocytosis (IP) and HE but was even more abnormal in hereditary pyropoikilocytosis (HPP). Addition of 2,3-DPG (2.55 mM) to IP or HE ghosts, decreased their stability to that of HPP ghosts (without 2,3-DPG). Nonphysiological 2,3-DPG levels (6-8 mM) were required to elicit a similar effect in normal ghosts. The data suggest that free 2,3-DPG, present in neonatal RBC as a consequence of diminished binding to HbF, may render HE susceptible to in vivo fragmentation. The developmental switch from fetal to adult hemoglobin, by diminishing available free 2,3-DPG, may explain the abatement of poikilocytosis and hemolytic anemia that accompanies maturation. Images PMID:3818955

  4. Chemical Surface, Thermal and Electrical Characterization of Nafion Membranes Doped with IL-Cations

    Directory of Open Access Journals (Sweden)

    María del Valle Martínez de Yuso

    2014-04-01

    Full Text Available Surface and bulk changes in a Nafion membrane as a result of IL-cation doping (1-butyl-3-methylimidazolium tetrafluoroborate or BMIM+BF4 and phenyltrimethylammonium chloride or TMPA+Cl− were studied by X-ray photoelectron spectroscopy (XPS, contact angle, differential scanning calorimetry (DSC and impedance spectroscopy (IS measurements performed with dry samples after 24 h in contact with the IL-cations BMIM+ and TMPA+. IL-cations were selected due to their similar molecular weight and molar volume but different shape, which could facilitate/obstruct the cation incorporation in the Nafion membrane structure by proton/cation exchange mechanism. The surface coverage of the Nafion membrane by the IL-cations was confirmed by XPS analysis and contact angle, while the results obtained by the other two techniques (DSC and IS seem to indicate differences in thermal and electrical behaviour depending on the doping-cation, being less resistive the Nafion/BMIM+ membrane. For that reason, determination of the ion transport number was obtained for this membrane by measuring the membrane or concentration potential with the samples in contact with HCl solutions at different concentrations. The comparison of these results with those obtained for the original Nafion membrane provides information on the effect of IL-cation BMIM+ on the transport of H+ across wet Nafion/BMIM+ doped membranes.

  5. Water and chemical savings in cooling towers by using membrane capacitive deionization

    NARCIS (Netherlands)

    Limpt, van B.; Wal, van der A.

    2014-01-01

    Membrane capacitive deionization (MCDI) is a water desalination technology based on applying a voltage difference between two oppositely placed porous carbon electrodes. In front of each electrode, an ion exchange membrane is positioned, and between them, a spacer is situated, which transports the

  6. Bifurcation and stability analysis of rotating chemical spirals in circular domains: Boundary-induced meandering and stabilization

    Science.gov (United States)

    Bär, Markus; Bangia, Anil K.; Kevrekidis, Ioannis G.

    2003-05-01

    Recent experimental and model studies have revealed that the domain size may strongly influence the dynamics of rotating spirals in two-dimensional pattern forming chemical reactions. Hartmann et al. [Phys. Rev. Lett. 76, 1384 (1996)], report a frequency increase of spirals in circular domains with diameters substantially smaller than the spiral wavelength in a large domain for the catalytic NO+CO reaction on a microstructured platinum surface. Accompanying simulations with a simple reaction-diffusion system reproduced the behavior. Here, we supplement these studies by a numerical bifurcation and stability analysis of rotating spirals in a simple activator-inhibitor model. The problem is solved in a corotating frame of reference. No-flux conditions are imposed at the boundary of the circular domain. At large domain sizes, eigenvalues and eigenvectors very close to those corresponding to infinite medium translational invariance are observed. Upon decrease of domain size, we observe a simultaneous change in the rotation frequency and a deviation of these eigenvalues from being neutrally stable (zero real part). The latter phenomenon indicates that the translation symmetry of the spiral solution is appreciably broken due to the interaction with the (now nearby) wall. Various dynamical regimes are found: first, the spiral simply tries to avoid the boundary and its tip moves towards the center of the circular domain corresponding to a negative real part of the “translational” eigenvalues. This effect is noticeable at a domain radius of R

  7. OXYGEN TRANSPORT CERAMIC MEMBRANES

    International Nuclear Information System (INIS)

    Dr. Sukumar Bandopadhyay; Dr. Nagendra Nagabhushana

    2001-01-01

    Conversion of natural gas to liquid fuels and chemicals is a major goal for the Nation as it enters the 21st Century. Technically robust and economically viable processes are needed to capture the value of the vast reserves of natural gas on Alaska's North Slope, and wean the Nation from dependence on foreign petroleum sources. Technologies that are emerging to fulfill this need are all based syngas as an intermediate. Syngas (a mixture of hydrogen and carbon monoxide) is a fundamental building block from which chemicals and fuels can be derived. Lower cost syngas translates directly into more cost-competitive fuels and chemicals. The currently practiced commercial technology for making syngas is either steam methane reforming (SMR) or a two-step process involving cryogenic oxygen separation followed by natural gas partial oxidation (POX). These high-energy, capital-intensive processes do not always produce syngas at a cost that makes its derivatives competitive with current petroleum-based fuels and chemicals. This project has the following 6 main tasks: Task 1--Design, fabricate and evaluate ceramic to metal seals based on graded ceramic powder/metal braze joints. Task 2--Evaluate the effect of defect configuration on ceramic membrane conductivity and long term chemical and structural stability. Task 3--Determine materials mechanical properties under conditions of high temperatures and reactive atmospheres. Task 4--Evaluate phase stability and thermal expansion of candidate perovskite membranes and develop techniques to support these materials on porous metal structures. Task 5--Assess the microstructure of membrane materials to evaluate the effects of vacancy-impurity association, defect clusters, and vacancy-dopant association on the membrane performance and stability. Task 6--Measure kinetics of oxygen uptake and transport in ceramic membrane materials under commercially relevant conditions using isotope labeling techniques

  8. Effect of Cation Ordering on the Performance and Chemical Stability of Layered Double Perovskite Cathodes

    Directory of Open Access Journals (Sweden)

    Carlos Bernuy-Lopez

    2018-01-01

    Full Text Available The effect of A-site cation ordering on the cathode performance and chemical stability of A-site cation ordered LaBaCo2O5+δ and disordered La0.5Ba0.5CoO3−δ materials are reported. Symmetric half-cells with a proton-conducting BaZr0.9Y0.1O3−δ electrolyte were prepared by ceramic processing, and good chemical compatibility of the materials was demonstrated. Both A-site ordered LaBaCo2O5+δ and A-site disordered La0.5Ba0.5CoO3−δ yield excellent cathode performance with Area Specific Resistances as low as 7.4 and 11.5 Ω·cm2 at 400 °C and 0.16 and 0.32 Ω·cm2 at 600 °C in 3% humidified synthetic air respectively. The oxygen vacancy concentration, electrical conductivity, basicity of cations and crystal structure were evaluated to rationalize the electrochemical performance of the two materials. The combination of high-basicity elements and high electrical conductivity as well as sufficient oxygen vacancy concentration explains the excellent performance of both LaBaCo2O5+δ and La0.5Ba0.5CoO3−δ materials at high temperatures. At lower temperatures, oxygen-deficiency in both materials is greatly reduced, leading to decreased performance despite the high basicity and electrical conductivity. A-site cation ordering leads to a higher oxygen vacancy concentration, which explains the better performance of LaBaCo2O5+δ. Finally, the more pronounced oxygen deficiency of the cation ordered polymorph and the lower chemical stability at reducing conditions were confirmed by coulometric titration.

  9. Rescue of glaucoma-causing mutant myocilin thermal stability by chemical chaperones

    Science.gov (United States)

    Burns, J. Nicole; Orwig, Susan D.; Harris, Julia L.; Watkins, J. Derrick; Vollrath, Douglas; Lieberman, Raquel L.

    2010-01-01

    Mutations in myocilin cause an inherited form of open angle glaucoma, a prevalent neurodegenerative disorder associated with increased intraocular pressure. Myocilin forms part of the trabecular meshwork extracellular matrix presumed to regulate intraocular pressure. Missense mutations, clustered in the olfactomedin (OLF) domain of myocilin, render the protein prone to aggregation in the endoplasmic reticulum of trabecular meshwork cells, causing cell dysfunction and death. Cellular studies have demonstrated temperature-sensitive secretion of myocilin mutants, but difficulties in expression and purification have precluded biophysical characterization of wild-type (wt) myocilin and disease-causing mutants in vitro. We have overcome these limitations by purifying wt and select glaucoma-causing mutant (D380A, I477N, I477S, K423E) forms of the OLF domain (228–504) fused to maltose binding protein (MBP) from E. coli. Monomeric fusion proteins can be isolated in solution. To determine the relative stability of wt and mutant OLF domains, we developed a fluorescence thermal stability assay without removal of MBP, and provide the first direct evidence that mutated OLF is folded but less thermally stable than wt. We tested the ability of seven chemical chaperones to stabilize mutant myocilin. Only sarcosine and trimethylamine N-oxide were capable of shifting the melting temperature of all mutants tested to near that of wt OLF. Our work lays the foundation for the identification of tailored small molecules capable of stabilizing mutant myocilin and promoting secretion to the extracellular matrix, to better control intraocular pressure and ultimately delay the onset of myocilin glaucoma. PMID:20334347

  10. Wet-chemical passivation of InAs: toward surfaces with high stability and low toxicity.

    Science.gov (United States)

    Jewett, Scott A; Ivanisevic, Albena

    2012-09-18

    In a variety of applications where the electronic and optical characteristics of traditional, siliconbased materials are inadequate, recently researchers have employed semiconductors made from combinations of group III and V elements such as InAs. InAs has a narrow band gap and very high electron mobility in the near-surface region, which makes it an attractive material for high performance transistors, optical applications, and chemical sensing. However, silicon-based materials remain the top semiconductors of choice for biological applications, in part because of their relatively low toxicity. In contrast to silicon, InAs forms an unstable oxide layer under ambient conditions, which can corrode over time and leach toxic indium and arsenic components. To make InAs more attractive for biological applications, researchers have investigated passivation, chemical and electronic stabilization, of the surface by adlayer adsorption. Because of the simplicity, low cost, and flexibility in the type of passivating molecule used, many researchers are currently exploring wet-chemical methods of passivation. This Account summarizes much of the recent work on the chemical passivation of InAs with a particular focus on the chemical stability of the surface and prevention of oxide regrowth. We review the various methods of surface preparation and discuss how crystal orientation affects the chemical properties of the surface. The correct etching of InAs is critical as researchers prepare the surface for subsequent adlayer adsorption. HCl etchants combined with a postetch annealing step allow the tuning of the chemical properties in the near-surface region to either arsenic- or indium-rich environments. Bromine etchants create indium-rich surfaces and do not require annealing after etching; however, bromine etchants are harsh and potentially destructive to the surface. The simultaneous use of NH(4)OH etchants with passivating molecules prevents contact with ambient air that can

  11. Stabilization of contaminated soil and wastewater with chemically bonded phosphate ceramics

    International Nuclear Information System (INIS)

    Wagh, A.S.; Jeong, S.Y.; Singh, D.

    1997-01-01

    At Argonne National Laboratory, we have developed chemically Bonded phosphate ceramic (CBPC) technology to stabilize the U.S. Department of Energy's problem mixed waste streams, for which no other stabilization technology is suitable. In this technology, solid waste is mixed with MgO and reacted with aqueous solutions of phosphoric acid or acid phosphates at room temperature to form a slurry that sets in ∼2 h into a hard and dense ceramic waste form. Initial studies involved stabilizing the surrogate waste streams and then testing the waste forms for leaching of contaminants. After achieving satisfactory performance of the waste forms, we next incorporated actual waste streams at bench scale and produced waste forms that were then tested with the Toxicity Characteristic Leaching Procedure (TCLP). This presentation deals with stabilization of soil contaminated with Cd, Cr, Pb, Ag, Ba, and Hg, and of low-level radioactive wastewater. To enhance the contaminant levels in the soil, we further spiked the soil with additional amounts of Cd, Cr, Pb, and Hg. Both the soil and the wastewater were incorporated in the same waste form by stabilizing them with the CBPC process. The waste forms had a total waste loading of ∼77 wt.% and were dense with an open porosity of 2.7 vol.% and a density of 2.17 g/cm 3 . Compression strength was 4910 psi. The TCLP results showed excellent immobilization of all the RCRA metals, and radioactive contaminant levels were below the detection limit of 0.2 pCi/mL. Long-term leaching studies using the ANS 16.1 procedure showed that the retention of contaminants is excellent and comparable to or better than most of other stabilization processes. These results demonstrate that the CBPC process is a very superior process for treatment of low level mixed wastes; we therefore conclude that the CBPC process is well suited to the treatment of low-level mixed waste streams with high waste loading

  12. Functional and chemical stability of a medicinal herb, Artemisia capillaris, following gamma sterilization

    Energy Technology Data Exchange (ETDEWEB)

    Jung, Uhee; Jeong, Ill Yun; Bae, Mun Hyoung; Byun, Myung Woo; Jo, Sung Kee [Radiation Research Center for Biotechnology, Advanced Radiation Technology Institute, Korea Atomic Energy Research Institute, Jeongeup (Korea, Republic of)

    2007-08-15

    The stability of functional and chemical properties of gamma-irradiated (10 kGy) Artemisia capillaris, a widely used herb in the traditional Oriental medicine, was investigated. Functional properties of the extracts of gamma-irradiated and non-irradiated A. capillaris were compared in antioxidant activities, such as 1,1-diphenyl-2-picryl hydrazyl (DPPH) radical and superoxide anion radical scavenging, lipid peroxidation inhibition, and protection of lymphocyte and plasmid DNA. Their chemical properties were assessed by HPLC analysis, comparing with chlorogenic acid and caffeic acid, which were isolated from ethylacetate fraction as major compounds with strong antioxidant activities. No significant difference in functional properties between irradiated and non-irradiated A. capillaris was found in all antioxidant assays. Also HPLC analysis of ethyl acetate fractions of irradiated and non-irradiated A. capillaris revealed the preservation of chlorogenic acid ({sub t}R=3.124 min) and caffeic acid ({sub t}R=3.672 min), and showed almost the same pattern in the general peaks. These results suggest that the chemical components and antioxidant properties of A. capillaris are not affected largely by gamma-ray irradiation. Therefore, this study may provide evidence that the irradiated herbs retain their potential functional properties.

  13. Correlations of the glycemic variability with oxidative stress and erythrocytes membrane stability in patients with type 1 diabetes under intensive treatment.

    Science.gov (United States)

    Rodrigues, Ricardo; Alves de Medeiros, Luciana; Moreira Cunha, Lucas; da Silva Garrote-Filho, Mario; Bernardino Neto, Morun; Tannus Jorge, Paulo; Santos Resende, Elmiro; Penha-Silva, Nilson

    2018-02-07

    This study aimed to evaluate the correlations of glycemic variability with erythrocyte membrane stability parameters and oxidative stress markers in patients with DM1 under intensive treatment. 90 patients with DM1 and under intensive treatment of the disease were evaluated in relation to anthropometric indices, records of glycemic averages and parameters of glycemic variability, biochemical dosages (glucose, uric acid, lipidogram, glycated hemoglobin, microalbuminuria, creatinine and iron) reticulocyte count, erythrocyte membrane stability parameters and oxidative stress markers (thiobarbituric acid reactive substances, TBARS, and glutathione reductase, GR). Indicators of glycemic variability in the short and long term showed correlations with parameters of membrane stability and markers of oxidative stress (GR). In addition, the comparison of these same parameters between the subgroups consisting of quartiles of GV or glycemic control also showed significant differences. In the DM1 patients studied here, glycemic variability showed correlations with oxidative stress and erythrocyte membrane stability variables. This corroborates the hypothesis that glycemic fluctuations interfere with lipid peroxidation and cell membrane behavior, emphasizing its participation in mechanisms related to the development of chronic complications of diabetes. Copyright © 2018 Elsevier B.V. All rights reserved.

  14. Plasma-chemical modification of the structure and properties of poly(ethylene terephthalate) track membranes

    International Nuclear Information System (INIS)

    Kravets, L I; Dmitriev, S N; Dinescu, G; Lazea, A; Sleptsov, V V; Elinson, V M

    2007-01-01

    A process of extraction of the low-molecular products of the synthesis from the poly(ethylene terephthalate) track membranes modified by plasma has been investigated. It is shown that the deposition of a thin polymeric hydrocarbon film by cyclohexane plasma on the membrane surface with preliminary treatment in a plasma of non-polymerizing gases, for example oxygen, allows one to produce membranes possessing a high productivity. Their advantages are much better hydrodynamic properties and a small amount of the low-molecular products of the synthesis extracted by organic solvents

  15. Application of membrane LaF3 electrode in the determination of stability constants of Uranyl Fluoride complex in solution

    International Nuclear Information System (INIS)

    Muzakky; Iswani GS; Mintolo

    1996-01-01

    A membrane electrode LaF 3 has been applied in the determination of uranyl fluoride complex stability constant in solution. The determination is based on the detection of free F ion in solution as a result of hydrolysis reaction (process) of uranyl ions into the uranyl hydroxide form at low pH. The experiment results showed that there was no effect of ammonium carbonate 2 M titran, flow rate on the electrode response. The F release is optimum at pH 1. The free F ion in solution is calculated from the standard curve at pH 1, after the fluoride concentration at the same pH has been corrected. Using the plot of average number of ligand binding (n) versus minus log of free ligand (-log F) the value of β1 = 4.4, β2 = 7.48, β3=9.73, and β4 = 11.67

  16. Comment on the Long-Term Chemical and Mineralogical Stability of the Buffer

    International Nuclear Information System (INIS)

    Arthur, Randy; Apted, Mick; Stenhouse, Mike

    2005-03-01

    This report examines concepts and data that SKB may use to assess the long-term chemical and mineralogical evolution of bentonite barriers in a KBS-3 repository for spent nuclear fuel. Three interrelated topics are considered: mineral chemistry of the smectite clays; thermodynamic stability of the smectite clays; and bentonite-water interactions during the early thermal period of repository evolution. Smectites are complex solid solutions having variable compositions resulting from ionic substitutions on exchange, octahedral and tetrahedral sites in the crystalline lattice. Although little is known about the mechanisms and rates of reactions involving the latter two sites, abundant observational evidence from natural systems suggests that such reactions could occur to an appreciable extent in the buffer over the million year time frame being considered for an intact canister. We are not aware of any efforts in SKB's current modeling strategy to account for such reactions, and therefore question whether the strategy is appropriate for modeling the long-term chemical evolution of the buffer and associated potential effects on the desirable physical and rheological properties of this barrier material. The variable chemistry of smectites affects their thermodynamic stability. Models of smectite-water equilibria use either a fixed stoichiometric composition to approximate representative smectite varieties, or account for compositional variations using solid solution models and ideal mixing relations among thermodynamic components. In either case the thermodynamic properties of a specific smectite composition or of individual solid-solution components must usually be estimated. Recent reports suggest that SKB will not account explicitly for the thermodynamic properties of smectite in its models of bentonite-water interactions. Rather, the models will assume that this clay mineral has a fixed, though unspecified, composition representing an ion-exchanger phase. This phase

  17. Influences of the Structure of Lipids on Thermal Stability of Lipid Membranes

    International Nuclear Information System (INIS)

    Hai Nan-Nan; Zhou Xin; Li Ming

    2015-01-01

    The binding free energy (BFE) of lipid to lipid bilayer is a critical factor to determine the thermal or mechanical stability of the bilayer. Although the molecular structure of lipids has significant impacts on BFE of the lipid, there lacks a systematic study on this issue. In this paper we use coarse-grained molecular dynamics simulation to investigate this problem for several typical phospholipids. We find that both the tail length and tail unsaturation can significantly affect the BFE of lipids but in opposite way, namely, BFE decreases linearly with increasing length, but increases linearly with addition of unsaturated bonds. Inspired by the specific structure of cholesterol which is a crucial component of biomembrane, we also find that introduction of carbo-ring-like structures to the lipid tail or to the bilayer may greatly enhance the stability of the bilayer. Our simulation also shows that temperature can influence the bilayer stability and this effect can be significant when the bilayer undergoes phase transition. These results may be helpful to the design of liposome or other self-assembled lipid systems. (paper)

  18. The effect of peptides and ions interacting with an electrically neutral membrane interface on the structure and stability of lipid membranes in the liquid-crystalline phase and in the liquid-ordered phase

    Energy Technology Data Exchange (ETDEWEB)

    Sano, Ryoko [Department of Physics, Faculty of Science, Shizuoka University, Shizuoka, 422-8529 (Japan); Masum, Shah Md [Material Science, Graduate School of Science and Engineering, Shizuoka University, 422-8529 (Japan); Tanaka, Tomoki [Material Science, Graduate School of Science and Engineering, Shizuoka University, 422-8529 (Japan); Yamashita, Yuko [Department of Physics, Faculty of Science, Shizuoka University, Shizuoka, 422-8529 (Japan); Levadny, Victor [Department of Physics, Faculty of Science, Shizuoka University, Shizuoka, 422-8529 (Japan); Scientific Council for Cybernetics, Russian Academy of Sciences, Vavilov street 34, 333117, Moscow (Russian Federation); Yamazaki, Masahito [Department of Physics, Faculty of Science, Shizuoka University, Shizuoka, 422-8529 (Japan); Material Science, Graduate School of Science and Engineering, Shizuoka University, 422-8529 (Japan)

    2005-08-10

    We investigated the effects of a de novo designed peptide, WLFLLKKK (peptide-1) and La{sup 3+}, which can bind with the electrically neutral lipid membrane interface, on the stability of the phosphatidylcholine (PC) membrane in the L{sub {alpha}} phase and that of the liquid-ordered (lo) phase membranes. The results of spacing of the multilamellar vesicle and shape changes of the giant unilamellar vesicle (GUV) indicate that the peptide-1 can be partitioned into the membrane interface in the L{sub {alpha}} phase but not into that in the lo phase. La{sup 3+} induced shape changes of GUVs of the lo phase membrane, which are the same as those of GUVs in the L{sub {alpha}} phase. This indicates that the binding of La{sup 3+} induced an increase in the lateral compression pressure of the membrane, which decreased the surface area of the membrane in the lo phase. The difference of the membrane interface between the L{sub {alpha}} phase and the lo phase is discussed.

  19. The effect of peptides and ions interacting with an electrically neutral membrane interface on the structure and stability of lipid membranes in the liquid-crystalline phase and in the liquid-ordered phase

    International Nuclear Information System (INIS)

    Sano, Ryoko; Masum, Shah Md; Tanaka, Tomoki; Yamashita, Yuko; Levadny, Victor; Yamazaki, Masahito

    2005-01-01

    We investigated the effects of a de novo designed peptide, WLFLLKKK (peptide-1) and La 3+ , which can bind with the electrically neutral lipid membrane interface, on the stability of the phosphatidylcholine (PC) membrane in the L α phase and that of the liquid-ordered (lo) phase membranes. The results of spacing of the multilamellar vesicle and shape changes of the giant unilamellar vesicle (GUV) indicate that the peptide-1 can be partitioned into the membrane interface in the L α phase but not into that in the lo phase. La 3+ induced shape changes of GUVs of the lo phase membrane, which are the same as those of GUVs in the L α phase. This indicates that the binding of La 3+ induced an increase in the lateral compression pressure of the membrane, which decreased the surface area of the membrane in the lo phase. The difference of the membrane interface between the L α phase and the lo phase is discussed

  20. Evaluation of a Silicone Membrane as an Alternative to Human Skin for Determining Skin Permeation Parameters of Chemical Compounds.

    Science.gov (United States)

    Uchida, Takashi; Yakumaru, Masafumi; Nishioka, Keisuke; Higashi, Yoshihiro; Sano, Tomohiko; Todo, Hiroaki; Sugibayashi, Kenji

    2016-01-01

    We evaluated the effectiveness of a silicone membrane as an alternative to human skin using the skin permeation parameters of chemical compounds. An in vitro permeation study using 15 model compounds was conducted, and permeation parameters comprising permeability coefficient (P), diffusion parameter (DL(-2)), and partition parameter (KL) were calculated from each permeation profile. Significant correlations were obtained in log P, log DL(-2), and log KL values between the silicone membrane and human skin. DL(-2) values of model compounds, except flurbiprofen, in the silicone membrane were independent of the lipophilicity of the model compounds and were 100-fold higher than those in human skin. For antipyrine and caffeine, which are hydrophilic, KL values in the silicone membrane were 100-fold lower than those in human skin, and P values, calculated as the product of a DL(-2) and KL, were similar. For lipophilic compounds, such as n-butyl paraben and flurbiprofen, KL values for silicone were similar to or 10-fold higher than those in human skin, and P values for silicone were 100-fold higher than those in human skin. Furthermore, for amphiphilic compounds with log Ko/w values from 0.5 to 3.5, KL values in the silicone membrane were 10-fold lower than those in human skin, and P values for silicone were 10-fold higher than those in human skin. The silicone membrane was useful as a human skin alternative in an in vitro skin permeation study. However, depending on the lipophilicity of the model compounds, some parameters may be over- or underestimated.

  1. Fouling of Seawater Reverse Osmosis (SWRO) Membrane: Chemical and Microbiological Characterization

    KAUST Repository

    Khan, Muhammad T.

    2013-01-01

    In spite of abundant water resources, world is suffering from the scarcity of usable water. Seawater Reverse Osmosis (SWRO) desalination technology using polymeric membranes has been recognized as a key solution to water scarcity problem. However

  2. Proton-Conducting Sulfonated and Phosphonated Polymers and Fuel Cell Membranes by Chemical Modification of Polysulfones

    OpenAIRE

    Lafitte, Benoit

    2007-01-01

    The proton exchange membrane fuel cell (PEMFC) is currently emerging as an efficient and environmentally friendly power source. The technology is very complex and relies ultimately on materials and components which need further development. One of the major hurdles for advancing the PEMFC technology is currently the demand for new durable low-cost polymeric membranes that will allow fuel cell operation at high temperatures without extensive humidification requirements. Thus, the design and pr...

  3. YNi and its hydrides: Phase stabilities, electronic structures and chemical bonding properties from first principles

    International Nuclear Information System (INIS)

    Matar, S.F.; Nakhl, M.; Al Alam, A.F.; Ouaini, N.; Chevalier, B.

    2010-01-01

    Graphical abstract: Base centered orthorhombic YNiH X structure. For x = 3, only H1 and H2 are present. Highest hydrogen content YNiH 4 is obtained when H3 are added. - Abstract: Within density functional theory, establishing the equations of states of YNi in two different controversial structures in the literature, leads to determine the orthorhombic FeB-type as the ground state one with small energy difference. For YNiH 3 and YNiH 4 hydrides crystallizing in the orthorhombic CrB-type structure the geometry optimization and the ab initio determination of the H atomic positions show that the stability of hydrogen decreases from the tri- to the tetra- hydride. New states brought by hydrogen within the valence band lead to its broadening and to enhanced localization of metal density of states. The chemical bonding analysis shows a preferential Ni-H bonding versus Y-H.

  4. YNi and its hydrides: Phase stabilities, electronic structures and chemical bonding properties from first principles

    Energy Technology Data Exchange (ETDEWEB)

    Matar, S.F., E-mail: matar@icmcb-bordeaux.cnrs.fr [CNRS, Universite de Bordeaux, ICMCB, 87 avenue du Docteur Albert Schweitzer, F-33608 Pessac (France); Nakhl, M. [Universite Libanaise, Laboratoire de Chimie-Physique des Materiaux LCPM, Fanar (Lebanon); Al Alam, A.F.; Ouaini, N. [Universite Saint-Esprit de Kaslik, Faculte des Sciences et de Genie Informatique, Jounieh (Lebanon); Chevalier, B. [CNRS, Universite de Bordeaux, ICMCB, 87 avenue du Docteur Albert Schweitzer, F-33608 Pessac (France)

    2010-11-25

    Graphical abstract: Base centered orthorhombic YNiH{sub X} structure. For x = 3, only H1 and H2 are present. Highest hydrogen content YNiH{sub 4} is obtained when H3 are added. - Abstract: Within density functional theory, establishing the equations of states of YNi in two different controversial structures in the literature, leads to determine the orthorhombic FeB-type as the ground state one with small energy difference. For YNiH{sub 3} and YNiH{sub 4} hydrides crystallizing in the orthorhombic CrB-type structure the geometry optimization and the ab initio determination of the H atomic positions show that the stability of hydrogen decreases from the tri- to the tetra- hydride. New states brought by hydrogen within the valence band lead to its broadening and to enhanced localization of metal density of states. The chemical bonding analysis shows a preferential Ni-H bonding versus Y-H.

  5. Chemical stability of {gamma}-butyrolactone-based electrolytes for aluminium electrolytic capacitors

    Energy Technology Data Exchange (ETDEWEB)

    Ue, Makoto [Mitsubishi Chemical Corp., Tsukuba Research Center, Ibaraki (Japan); Takeda, Masayuki [Mitsubishi Chemical Corp., Tsukuba Research Center, Ibaraki (Japan); Suzuki, Yoko [Mitsubishi Chemical Corp., Tsukuba Research Center, Ibaraki (Japan); Mori, Shoichiro [Mitsubishi Chemical Corp., Tsukuba Research Center, Ibaraki (Japan)

    1996-06-01

    {gamma}-Butyrolactone-based electrolytes have been used as the operating electrolytes for aluminum electrolytic capacitors. The chemical stability of these electrolytes at elevated temperatures has been examined by monitoring the decrease in their electrolytic conductivities. The deteriorated electrolytes were analyzed by gas and liquid chromatography and the conductivity decrease was directly correlated with the loss of acid components. In quaternary ammonium hydrogen maleate/{gamma}-butyrolactone electrolytes, the maleate anion decomposed by decarboxylation resulting in a complex polymer containing polyester and polyacrylate structures. Quaternary ammonium benzoate/{gamma}-butyrolactone electrolytes decomposed by SN2 reactions giving alkyl benzoates and trialkylamines. The deterioration of the carboxylate salt/{gamma}-butyrolactone electrolytes was accelerated by electrolysis. (orig.)

  6. Assessment of chromatographic methods for the chemical stability of a new miconazole nitrate cream

    International Nuclear Information System (INIS)

    Garcia Pulpeiro, Oscar; Calzadilla Aguiar, Wendy; Rodriguez Bencomo, Wendy

    2013-01-01

    To assess the chromatographic methods for the chemical stability of a new 2 % miconazol nitrate cream. arious degradation conditions were firstly used in the raw material miconazole nitrate in order to obtain the possible degradation products of this drug and to evaluate them by thin layer chromatography-based method, which was validated to identify the degradation products in the new cream. The performance of the official method based on high resolution liquid chromatography and reported in British Pharmacopoeia 2010 was evaluated, and its selectivity against the possible degradation products were also analyzed. Both chromatographic methods were applied to the analysis of cream samples from the three pilot batches under heat stress for 30 days

  7. Colour stability, staining and roughness of silorane after prolonged chemical challenges

    DEFF Research Database (Denmark)

    Benetti, Ana Raquel; Ribeiro de Jesus, Vivian Cristiane Bueno; Martinelli, Natan Luiz

    2013-01-01

    methacrylate or silorane composites. Specimens were individually stored at 37°C in 0.02 N citric acid, 0.02 N phosphoric acid, 75% ethanol or distilled water for 7, 14, 21 and 180 days, when new measurements were performed. A staining test was performed after the chemical challenge by immersion in coffee...... considered acceptable (although significantly different) after immersion in water, citric acid, phosphoric acid or ethanol, but were unacceptable for the silorane composite immersed in ethanol for 180 days. The methacrylate-based resins stored in ethanol were significantly more stained by coffee than those...... stored in other media. The silorane composite demonstrated no staining, but increased roughness, when compared to the methacrylate-based resins. CONCLUSIONS: No effect of the immersion solution was noticed on roughness of the investigated materials. Ethanol influenced colour stability and staining...

  8. Porous polycarbene-bearing membrane actuator for ultrasensitive weak-acid detection and real-time chemical reaction monitoring.

    Science.gov (United States)

    Sun, Jian-Ke; Zhang, Weiyi; Guterman, Ryan; Lin, Hui-Juan; Yuan, Jiayin

    2018-04-30

    Soft actuators with integration of ultrasensitivity and capability of simultaneous interaction with multiple stimuli through an entire event ask for a high level of structure complexity, adaptability, and/or multi-responsiveness, which is a great challenge. Here, we develop a porous polycarbene-bearing membrane actuator built up from ionic complexation between a poly(ionic liquid) and trimesic acid (TA). The actuator features two concurrent structure gradients, i.e., an electrostatic complexation (EC) degree and a density distribution of a carbene-NH 3 adduct (CNA) along the membrane cross-section. The membrane actuator performs the highest sensitivity among the state-of-the-art soft proton actuators toward acetic acid at 10 -6  mol L -1 (M) level in aqueous media. Through competing actuation of the two gradients, it is capable of monitoring an entire process of proton-involved chemical reactions that comprise multiple stimuli and operational steps. The present achievement constitutes a significant step toward real-life application of soft actuators in chemical sensing and reaction technology.

  9. Proton exchange membranes prepared by grafting of styrene/divinylbenzene into crosslinked PTFE membranes

    International Nuclear Information System (INIS)

    Li Jingye; Ichizuri, Shogo; Asano, Saneto; Mutou, Fumihiro; Ikeda, Shigetoshi; Iida, Minoru; Miura, Takaharu; Oshima, Akihiro; Tabata, Yoneho; Washio, Masakazu

    2005-01-01

    Thin PTFE membranes were prepared by coating the PTFE dispersion onto the aluminum films. Thus the thin crosslinked PTFE (RX-PTFE) membranes were obtained by means of electron beam irradiation above the melting temperature of PTFE under oxygen-free atmosphere. The RX-PTFE membranes were pre-irradiated and grafted by styrene with or without divinylbenzene (DVB) in liquid phase. The existence of DVB accelerated the initial grafting rate. The styrene grafted RX-PTFE membranes are white colored, on the other hand, the styrene/DVB grafted RX-PTFE membranes are colorless. The proton exchange membranes (PEMs) were obtained by sulfonating the grafted membranes using chlorosulfonic acid. The ion exchange capacity (IEC) values of the PEMs ranging from 1.5 to 2.8 meq/g were obtained. The PEMs made from the styrene/DVB grafted membranes showed higher chemical stability than those of the styrene grafted membranes under oxidative circumstance

  10. Thermal stability of chemically denatured green fluorescent protein (GFP) A preliminary study

    Energy Technology Data Exchange (ETDEWEB)

    Nagy, Attila; Malnasi-Csizmadia, Andras; Somogyi, Bela; Lorinczy, Denes

    2004-02-09

    Green fluorescent protein (GFP) is a light emitter in the bioluminescence reaction of the jellyfish Aequorea victoria. The protein consist of 238 amino acids and produces green fluorescent light ({lambda}{sub max}=508 nm), when irradiated with near ultraviolet light. The fluorescence is due to the presence of chromophore consisting of an imidazolone ring, formed by a post-translational modification of the tripeptide -Ser{sup 65}-Tyr{sup 66}-Gly{sup 67}-, which buried into {beta}-barrel. GFP is extremely compact and heat stable molecule. In this work, we present data for the effect of chemical denaturing agent on the thermal stability of GFP. When denaturing agent is applied, global thermal stability and the melting point of the molecule is decreases, that can be monitored with differential scanning calorimetry. The results indicate, that in 1-6 M range of GuHCl the melting temperature is decreasing continuously from 83 to 38 deg. C. Interesting finding, that the calculated calorimetric enthalpy decreases with GuHCl concentration up to 3 M (5.6-0.2 kJ mol{sup -1}), but at 4 M it jumps to 8.4 and at greater concentration it is falling down to 1.1 kJ mol{sup -1}. First phenomena, i.e. the decrease of melting point with increasing GuHCl concentration can be easily explained by the effect of the extended chemical denaturation, when less and less amount of heat required to diminish the remaining hydrogen bonds in {beta}-barrel. The surprising increase of calorimetric enthalpy at 4 M concentration of GuHCl could be the consequence of a dimerization or a formation of stable complex between GFP and denaturing agent as well as a precipitation at an extreme GuHCl concentration. We are planning further experiments to elucidate fluorescent consequence of these processes.

  11. Stability of transmembrane amyloid β-peptide and membrane integrity tested by molecular modeling of site-specific Aβ42 mutations.

    Directory of Open Access Journals (Sweden)

    Chetan Poojari

    Full Text Available Interactions of the amyloid β-protein (Aβ with neuronal cell membranes, leading to the disruption of membrane integrity, are considered to play a key role in the development of Alzheimer's disease. Natural mutations in Aβ42, such as the Arctic mutation (E22G have been shown to increase Aβ42 aggregation and neurotoxicity, leading to the early-onset of Alzheimer's disease. A correlation between the propensity of Aβ42 to form protofibrils and its effect on neuronal dysfunction and degeneration has been established. Using rational mutagenesis of the Aβ42 peptide it was further revealed that the aggregation of different Aβ42 mutants in lipid membranes results in a variety of polymorphic aggregates in a mutation dependent manner. The mutant peptides also have a variable ability to disrupt bilayer integrity. To further test the connection between Aβ42 mutation and peptide-membrane interactions, we perform molecular dynamics simulations of membrane-inserted Aβ42 variants (wild-type and E22G, D23G, E22G/D23G, K16M/K28M and K16M/E22G/D23G/K28M mutants as β-sheet monomers and tetramers. The effects of charged residues on transmembrane Aβ42 stability and membrane integrity are analyzed at atomistic level. We observe an increased stability for the E22G Aβ42 peptide and a decreased stability for D23G compared to wild-type Aβ42, while D23G has the largest membrane-disruptive effect. These results support the experimental observation that the altered toxicity arising from mutations in Aβ is not only a result of the altered aggregation propensity, but also originates from modified Aβ interactions with neuronal membranes.

  12. Isoparaffinic diluents for tri-n-butyl phosphate. Chemical, radiation-chemical stability, effect on tetravalent plutonium and thorium extraction

    International Nuclear Information System (INIS)

    Renard, E.V.; Pyatibratov, Yu.P.; Neumoev, N.V.; Chizhov, A.A.; Kulikov, I.A.; Gol'dfarb, Yu.Ya.; Sirotkina, I.G.; Semenova, T.I.

    1989-01-01

    By means of catalytic hydroisomerization of the n-paraffinic raw material in a reactor using alumino-platinum catalysts, there was attained a 45-90% degree of conversion of n-paraffins into branched iso-paraffins with mono- and dimethyl structure. From a batch of extensively isomerized n-paraffins, by carrying out the operations of distillation of the light (benzine) fraction, dearomatization, de-n-paraffinization and fractional distillation on a rectification column, isoparaffinic (99%) concentrates were obtained with a constant molecular weight, from iso-C 10 to isoC 15 . The solubility of plutonium and thorium nitrates in 30% solutions of TBP in iso-paraffins (mixtures of iso-paraffins with the same number of C-atoms) increases with decrease in the molecular weight of the iso-paraffin; a system with a 30% TBP in a mixture of iso-decanes practically does not stratify (∼104 g Pu/liter, 22-25 degree C). Nevertheless, a twofold increase (compared with NP) of the maximally permissible (up to the formation of the third phase) concentration, is attained when iso-paraffins are introduced into NP with a similar molecular composition in a 1:1 ratio. With respect to the main requirements demanded of diluents for radiochemical extractional operations, such as density, viscosity, boiling point, flash point, and freezing point, the chemical stability and radiation resistance, content of radioruthenium and radiozirconium, rate of stratification of two-phase systems, the synthetic iso-paraffin-containing solvents are as suitable as n-paraffins

  13. Chemical stabilization of subgrade soil for the strategic expeditionary landing field

    Science.gov (United States)

    Conaway, M. H.

    1983-06-01

    The Strategic Expeditionary Landing Field (SELF) is a military expeditionary-type airfield with an aluminum matted surface that is designed for sustained tactical and cargo airlift operations in an amphibious objective area. Because of the operational traffic parameters such as loads of the various types of aircraft, tire pressures and volume of traffic, a base layer must be constructed over subgrade soil support conditions which may be only marginal. The base layer could be constructed with conventional soil construction techniques (compaction) and yield the required strength. It would be difficult, however, to maintain this strength for the required one-year service life under many climatic conditions due to the degrading effects of water on the support capacity of many soils. Chemical soil stabilization with lime, portland cement and asphalt stabilizing agents could be used to treat the soil. These additives, when properly mixed with certain types of soils, initiate reactions which will increase soil support strength and enhance durability (resistance to the degrading effects of water). Technically, this procedure is quite viable but logistically, it may not be feasible.

  14. Chemical and physical stability of smectites and illite in electrolyte solutions: experimental study at 150 C

    International Nuclear Information System (INIS)

    Boutiche, M.

    1995-01-01

    Chemical interactions between electrolytic solutions commonly used i drilling muds and clays have been studies under P-T conditions similar to those of drillings (150 deg C) in order to determine the eventual consequences on the stability of clay rich formations. The experimental work has been carried out using several solutions (water, NaOH (pH 8, 10, 12), KCI (0,1, 1 2 mol./l), sea water, and K 2 CO 3 ) and clay minerals with low to high amounts of swelling layers (smectite (Na, Na-Ca, Ca), mixed layered illite-smectite minerals). Run products are studied by X-ray diffraction and electronic microprobe. Smectite layers show series of mineralogical changes (cation exchange in the interlayer site, formation of non-swelling layers, hydrolysis), which, however, do not yield to the formation of new minerals, except in the case of the interaction with K 2 CO 3 at 150 deg C (zeolite crystallisation). Cation exchange in the interlayer depends on the nature of the cation, cation concentration in the solution, exchange constants, and liquid/solid ratio. In dilute solutions ( 1 mol./l), because they favour the collapse of swelling layers, and dispersion. Solutions of K 2 CO 3 at 150 deg C are at the origin of the transformation of smectite to zeolites, and high pH - highly saline solutions are rather aggressive, and would probably not stabilize the argilites. (author)

  15. Stabilization of heavy oil-water emulsions using a bio/chemical emulsifier mixture

    Energy Technology Data Exchange (ETDEWEB)

    Farahbakhsh, A.; Taghizadeh, M.; Movagharnejad, K. [Chemical Engineering Department, Babol University of Technology, Babol (Iran, Islamic Republic of); Yakhchali, B. [National Institute of Genetic Engineering and Biotechnology, Tehran (Iran, Islamic Republic of)

    2011-11-15

    In this study, the viscosity reduction of heavy oil has been investigated through the formation of oil-water emulsion using a bio/chemical emulsifier mixture. Four bioemulsifiers from indigenous Rhodococcus ergthropolis and Bacillus licheniformis strains were used to stabilize a highly-viscous oil-in-water emulsion. The Taguchi method with an L{sub 9} orthogonal array design was used to investigate the effect of various control factors on the formation of the oil/water emulsions. An emulsion with lowest viscosity was formed using ACO4 strain. The substantial stability of the oil-in-water emulsion allows the heavy oil to be transported practically over long distances or remain stationary for a considerable period of time prior to utilization. As the result of Taguchi analysis, the temperature and concentration of the emulsifier had a significant influence on viscosity reduction of the emulsion. (Copyright copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  16. Thulium oxide fuel characterization study: Part 2, Environmental behavior and mechanical, thermal and chemical stability enhancement

    International Nuclear Information System (INIS)

    Nelson, C.A.

    1970-12-01

    A study was performed of the correlation between fuel form stability and exposure environment of (temperature and atmosphere). 100% Tm 2 O 3 , 80% Tm 2 O 3 /20% Yb 2 O 3 and 100% Yb 2 O 3 wafers were subjected to air, dynamic vacuum and static vacuum at temperatures to 2000 0 C for times to 100 hours. Results showed the Tm 2 O 3 /Yb 2 O 3 cubic structure to be unaffected by elemental levels of iron, aluminum, magnesium and silicon and unaffected by the environmental conditions imposed on the wafers. A second task emphasized the optimization of the thermal, mechanical and chemical stability of Tm 2 O 3 fuel forms. Enhancement was sought through process variable optimization and the addition of metal oxides to Tm 2 O 3 . CaO, TiO 2 and Al 2 O 3 were added to form a grain boundary precipitate to control fines generation. The presence of 1% additive was inadequate to depress the melting point of Tm 2 O 3 or to change the cubic crystalline structure of Tm 2 O 3 /Yb 2 O 3 . Tm 2 O 3 /Yb 2 O 3 wafers containing CaO developed a grain boundary phase that improved the resistance to fines generation. The presence of Yb 2 O 3 did not appear to measurably influence behavior

  17. Aerobic stability, chemical composition and ruminal degradability of sugarcane silage with glycerin from biodiesel

    Directory of Open Access Journals (Sweden)

    Marco Antonio Bensimon Gomes

    2015-06-01

    Full Text Available The experiment was performed with the objective of studying the ensiled sugarcane silage with 0, 5, 10, 15 and 20% of glycerin in experimental PVC silos. The aerobic stability was assessed by measuring the pH and the temperature of the silage at 0, 24, 48, 72, 96 and 120h. The chemical composition, the levels of non-fiber carbohydrates (NFC and the total digestible nutrients (TDN were evaluated. The in vitro digestibility of dry matter (IVDDM and the in vitro digestibility of the cell wall (IVDCW in the silages were evaluated. In three fistulated cattle the in situ degradability of dry matter (DM and the disappearance percentage of the neutral detergent fiber (NDF in samples incubated at 0, 2, 6, 12, 24, 48, 72 and 96h were analyzed. The experimental design was completely randomized and the statistical analyzes were done using Bayesian inference. Increases were observed in DM, TDN, mineral matter, NFC and reductions in NDF, acid detergent fiber, crude protein and ether extract as the inclusion of glycerin was higher. IVDDM increased (P <0.05 in silage with 15 and 20% of glycerin in relation to those with 0, 5 and 10%. The IVDCW at levels of 10, 15 and 20% of glycerin was higher (P <0.05 compared to the other treatments. Increases were observed in the soluble portion (a, a reduction in the insoluble fraction (b, and an increase in the degradability fraction constant (c of the silages with 5, 10, 15 and 20% of glycerin (P <0.05 compared to the control. Glycerin improved aerobic stability while maintaining a low pH and temperature during the observation period at levels of 15 and 20% of glycerin against the silage with 0, 5 and 10%. These results indicate glycerin as a promising additive for sugarcane silage, being able to enhance energy density and improve the aerobic stability of the ensiled matter when its inclusion is from 10 to 20%.

  18. Stability and performance improvement of a polymer electrolyte membrane fuel cell stack by laser perforation of gas diffusion layers

    Energy Technology Data Exchange (ETDEWEB)

    Gerteisen, Dietmar; Sadeler, Christian [Fraunhofer Institute for Solar Energy Systems ISE, Department of Energy Technology, Heidenhofstrasse 2, 79110 Freiburg (Germany)

    2010-08-15

    The performance and stability of a hydrogen-driven polymer electrolyte membrane fuel cell stack (6-cell PEFC stack) are investigated with regard to pore flooding within the gas diffusion layers (GDLs). Two short stacks with various GDLs (Toray TGP-H-060 untreated and laser-perforated) were characterized at different operating conditions by several characterization techniques such as constant current load, polarization curve, chronoamperometry and chronovoltammetry. The experimental results reveal that the perforation of the cathode GDLs improves the water transport in the porous media and thus the performance as well as the stability of the operating stack in medium and high current density range. A reduced pore flooding is verified when using the customized laser-perforated GDLs. The GDL perforation has a huge potential to balance the inhomogeneous in-plane saturation conditions between the inlet and outlet area of the cell and to compensate to a certain degree the effects of temperature distribution within a stack regarding the water management. (author)

  19. Stability and performance improvement of a polymer electrolyte membrane fuel cell stack by laser perforation of gas diffusion layers

    Science.gov (United States)

    Gerteisen, Dietmar; Sadeler, Christian

    The performance and stability of a hydrogen-driven polymer electrolyte membrane fuel cell stack (6-cell PEFC stack) are investigated with regard to pore flooding within the gas diffusion layers (GDLs). Two short stacks with various GDLs (Toray TGP-H-060 untreated and laser-perforated) were characterized at different operating conditions by several characterization techniques such as constant current load, polarization curve, chronoamperometry and chronovoltammetry. The experimental results reveal that the perforation of the cathode GDLs improves the water transport in the porous media and thus the performance as well as the stability of the operating stack in medium and high current density range. A reduced pore flooding is verified when using the customized laser-perforated GDLs. The GDL perforation has a huge potential to balance the inhomogeneous in-plane saturation conditions between the inlet and outlet area of the cell and to compensate to a certain degree the effects of temperature distribution within a stack regarding the water management.

  20. Size-Controlled AgI/Ag Heteronanowires in Highly Ordered Alumina Membranes: Superionic Phase Stabilization and Conductivity.

    Science.gov (United States)

    Zhang, Hemin; Tsuchiya, Takashi; Liang, Changhao; Terabe, Kazuya

    2015-08-12

    Nanoscaled ionic conductors are crucial for future nanodevices. A well-known ionic conductor, AgI, exhibited conductivity greater than 1 Ω(-1) cm(-1) in α-phase and transformed into poorly conducting β-/γ-phase below 147 °C, thereby limiting applications. Here, we report that transition temperatures both from the β-/γ- to α-phase (Tc↑) and the α- to β-/γ-phase (Tc↓) are tuned by AgI/Ag heteronanowires embedded in anodic aluminum oxide (AAO) membranes with 10-30 nm pores. Tc↑ and Tc↓ shift to correspondingly higher and lower temperature as pore size decreases, generating a progressively enlarged thermal hysteresis. Tc↑ and Tc↓ specifically achieve 185 and 52 °C in 10 nm pores, and the final survived conductivity reaches ∼8.3 × 10(-3) Ω(-1) cm(-1) at room temperature. Moreover, the low-temperature stabilizing α-phase (down to 21 °C, the lowest in state of the art temperatures) is reproducible and survives further thermal cycling. The low-temperature phase stabilization and enhancement conductivity reported here suggest promising applications in silver-ion-based future nanodevices.

  1. Conformational stabilization of the membrane embedded targeting domain of the lysosomal peptide transporter TAPL for solution NMR

    Energy Technology Data Exchange (ETDEWEB)

    Tumulka, Franz [Goethe-University Frankfurt, Institute of Biochemistry, Biocenter (Germany); Roos, Christian; Loehr, Frank [Goethe-University Frankfurt, Institute of Biophysical Chemistry, Biocenter (Germany); Bock, Christoph [Goethe-University Frankfurt, Institute of Biochemistry, Biocenter (Germany); Bernhard, Frank; Doetsch, Volker [Goethe-University Frankfurt, Institute of Biophysical Chemistry, Biocenter (Germany); Abele, Rupert, E-mail: abele@em.uni-frankfurt.de [Goethe-University Frankfurt, Institute of Biochemistry, Biocenter (Germany)

    2013-10-15

    The ATP binding cassette transporter TAPL translocates cytosolic peptides into the lumen of lysosomes driven by the hydrolysis of ATP. Functionally, this transporter can be divided into coreTAPL, comprising the transport function, and an additional N-terminal transmembrane domain called TMD0, which is essential for lysosomal targeting and mediates the interaction with the lysosomal associated membrane proteins LAMP-1 and LAMP-2. To elucidate the structure of this unique domain, we developed protocols for the production of high quantities of cell-free expressed TMD0 by screening different N-terminal expression tags. Independently of the amino acid sequence, high expression was detected for AU-rich sequences in the first seven codons, decreasing the free energy of RNA secondary structure formation at translation initiation. Furthermore, avoiding NGG codons in the region of translation initiation demonstrated a positive effect on expression. For NMR studies, conditions were optimized for high solubilization efficiency, long-term stability, and high quality spectra. A most critical step was the careful exchange of the detergent used for solubilization by the detergent dihexanoylphosphatidylcholine. Several constructs of different size were tested in order to stabilize the fold of TMD0 as well as to reduce the conformation exchange. NMR spectra with sufficient resolution and homogeneity were finally obtained with a TMD0 derivative only modified by a C-terminal His{sub 10}-tag and containing a codon optimized AT-rich sequence.

  2. Chemical stability of a cold-active cellulase with high tolerance toward surfactants and chaotropic agent

    Directory of Open Access Journals (Sweden)

    Thaís V. Souza

    2016-03-01

    Full Text Available CelE1 is a cold-active endo-acting glucanase with high activity at a broad temperature range and under alkaline conditions. Here, we examined the effects of pH on the secondary and tertiary structures, net charge, and activity of CelE1. Although variation in pH showed a small effect in the enzyme structure, the activity was highly influenced at acidic conditions, while reached the optimum activity at pH 8. Furthermore, to estimate whether CelE1 could be used as detergent additives, CelE1 activity was evaluated in the presence of surfactants. Ionic and nonionic surfactants were not able to reduce CelE1 activity significantly. Therefore, CelE1 was found to be promising candidate for use as detergent additives. Finally, we reported a thermodynamic analysis based on the structural stability and the chemical unfolding/refolding process of CelE1. The results indicated that the chemical unfolding proceeds as a reversible two-state process. These data can be useful for biotechnological applications.

  3. Chemical compounds and mechanisms involved in the formation and stabilization of foam in sparkling wines.

    Science.gov (United States)

    Kemp, Belinda; Condé, Bruna; Jégou, Sandrine; Howell, Kate; Vasserot, Yann; Marchal, Richard

    2018-02-08

    The visual properties of sparkling wine including foam and bubbles are an indicator of sparkling wine quality. Foam properties, particularly foam height (FH) and foam stability (TS), are significantly influenced by the chemical composition of the wine. This review investigates our current knowledge of specific chemical compounds and, the mechanisms by which they influence the foam properties of sparkling wines. Grape and yeast proteins, amino acids, polysaccharides, phenolic compounds, organic acids, fatty acids, ethanol and sugar are examined with respect to their contribution to foam characteristics in sparkling wines made with the Traditional, Transfer, and Charmat and carbonation methods. Contradictory results have been identified that appear to be due to the analytical methods used to measure and quantify compounds and foam. Biopolymer complexes are discussed and absent knowledge with regards to thaumatin-like proteins (TLPs), polysaccharides, amino acids, oak-derived phenolic compounds and organic acids are identified. Future research is also likely to concentrate on visual analysis of sparkling wines by in-depth imaging analysis and specific sensory analysis techniques.

  4. Silver-mediated base pairings: towards dynamic DNA nanostructures with enhanced chemical and thermal stability

    International Nuclear Information System (INIS)

    Swasey, Steven M; Gwinn, Elisabeth G

    2016-01-01

    The thermal and chemical fragility of DNA nanomaterials assembled by Watson–Crick (WC) pairing constrain the settings in which these materials can be used and how they can be functionalized. Here we investigate use of the silver cation, Ag + , as an agent for more robust, metal-mediated self-assembly, focusing on the simplest duplex building blocks that would be required for more elaborate Ag + –DNA nanostructures. Our studies of Ag + -induced assembly of non-complementary DNA oligomers employ strands of 2–24 bases, with varied base compositions, and use electrospray ionization mass spectrometry to determine product compositions. High yields of duplex products containing narrowly distributed numbers of Ag + can be achieved by optimizing solution conditions. These Ag + -mediated duplexes are stable to at least 60 mM Mg 2+ , higher than is necessary for WC nanotechnology schemes such as tile assemblies and DNA origami, indicating that sequential stages of Ag + -mediated and WC-mediated assembly may be feasible. Circular dichroism spectroscopy suggests simple helical structures for Ag + -mediated duplexes with lengths to at least 20 base pairs, and further indicates that the structure of cytosine-rich duplexes is preserved at high urea concentrations. We therefore propose an approach towards dynamic DNA nanomaterials with enhanced thermal and chemical stability through designs that combine sturdy silver-mediated ‘frames’ with WC paired ‘pictures’. (paper)

  5. Preparing for chemical terrorism: a study of the stability of expired pralidoxime (2-PAM).

    Science.gov (United States)

    Hoffman, Robert S; Mercurio-Zappala, Maria; Bouchard, Nicole; Ravikumar, Padinjarekuttu; Goldfrank, Lewis

    2012-03-01

    Oximes such as pralidoxime (2-PAM) are essential antidotes for life-threatening organophosphate poisoning. Unfortunately, oximes are expensive, have limited use, and have short shelf lives. As such, maintaining large stockpiles in preparation for terrorist activity is not always possible. We have demonstrated that atropine is stable well beyond its labeled shelf life and that recently expired 2-PAM was clinically efficacious in a series of poisoned patients. Because 2-PAM is often dosed empirically, clinical improvement does not guarantee pharmacological stability. We therefore chose to analyze the chemical stability of expired 2-PAM. Samples of lyophylized 2-PAM were maintained according to the manufacturer's recommendations for 20 years beyond the published shelf life. We studied 2-PAM contained in a MARK I autoinjector that was stored properly for 3 years beyond its expiration date. An Agilent LC/MSD 1100 with diode-array detector and an Agilent Sorbax SB-C-18, 4.6 × 150-mm, 5-μm column were used with the following solvent systems: water with 0.01% trifluoroacetic acid and methanol with 0.01% trifluoroacetic acid. Fresh reagent grade 2-PAM was used as a standard. Results were repeated for consistency. Lyophylized 2-PAM was a white powder that was clear and colorless in solution. Liquid chromatography was identical to the standard and resulted in 2 isolated peaks with identical mass spectra, suggesting that they are stereoisomers. The autoinjector discharged a clear, yellowish solution. In addition to the 2 peaks identified for lyophylized 2-PAM, a small third peak was identified with a mass spectra corresponding to the reported N -methyl pyridinium carboxaldehyde degradation product. When properly stored, lyophylized 2-PAM appears to be chemically stable well beyond its expiration date. Although the relative amount of degradation product found in solubilized (autoinjector) 2-PAM was small, it is unclear whether this may be toxic and therefore is of concern

  6. Chemical Stability Analysis of Hair Cleansing Conditioners under High-Heat Conditions Experienced during Hair Styling Processes

    Directory of Open Access Journals (Sweden)

    Derek A. Drechsel

    2018-03-01

    Full Text Available Chemical stability is a key component of ensuring that a cosmetic product is safe for consumer use. The objective of this study was to evaluate the chemical stability of commercially available hair cleansing conditioners subjected to high heat stresses from the styling processes of blow drying or straightening. Two hair cleansing conditioners were subjected to temperatures of 60 °C and 185 °C to simulate the use of a blow dryer or flatiron hair straightener, respectively and analyzed via Gas Chromatography-Mass Spectrometry (GC-MS, High-Performance Liquid Chromatography-UV (HPLC and Fourier-Transform Infrared Spectroscopy (FT-IR to capture a chemical profile of the samples. The resulting spectra from matched heated and unheated samples were compared to identify any changes in chemical composition. Overall, no differences in the spectra were observed between the heated and unheated samples at both temperatures evaluated. Specifically, no new peaks were observed during analysis, indicating that no degradation products were formed. In addition, all chemicals identified during GC-MS analysis were known listed ingredients of the products. In summary, no measurable changes in chemical composition were observed in the hair cleansing conditioner samples under high-heat stress conditions. The presented analytical methods can serve as an initial screening tool to evaluate the chemical stability of a cosmetic product under conditions of anticipated use.

  7. Modeling error and stability of endothelial cytoskeletal membrane parameters based on modeling transendothelial impedance as resistor and capacitor in series.

    Science.gov (United States)

    Bodmer, James E; English, Anthony; Brady, Megan; Blackwell, Ken; Haxhinasto, Kari; Fotedar, Sunaina; Borgman, Kurt; Bai, Er-Wei; Moy, Alan B

    2005-09-01

    Transendothelial impedance across an endothelial monolayer grown on a microelectrode has previously been modeled as a repeating pattern of disks in which the electrical circuit consists of a resistor and capacitor in series. Although this numerical model breaks down barrier function into measurements of cell-cell adhesion, cell-matrix adhesion, and membrane capacitance, such solution parameters can be inaccurate without understanding model stability and error. In this study, we have evaluated modeling stability and error by using a chi(2) evaluation and Levenberg-Marquardt nonlinear least-squares (LM-NLS) method of the real and/or imaginary data in which the experimental measurement is compared with the calculated measurement derived by the model. Modeling stability and error were dependent on current frequency and the type of experimental data modeled. Solution parameters of cell-matrix adhesion were most susceptible to modeling instability. Furthermore, the LM-NLS method displayed frequency-dependent instability of the solution parameters, regardless of whether the real or imaginary data were analyzed. However, the LM-NLS method identified stable and reproducible solution parameters between all types of experimental data when a defined frequency spectrum of the entire data set was selected on the basis of a criterion of minimizing error. The frequency bandwidth that produced stable solution parameters varied greatly among different data types. Thus a numerical model based on characterizing transendothelial impedance as a resistor and capacitor in series and as a repeating pattern of disks is not sufficient to characterize the entire frequency spectrum of experimental transendothelial impedance.

  8. Inorganic Membranes: Preparation and Application for Water Treatment and Desalination

    Science.gov (United States)

    McKay, Gordon; Buekenhoudt, Anita; Motmans, Filip; Khraisheh, Marwan; Atieh, Muataz

    2018-01-01

    Inorganic membrane science and technology is an attractive field of membrane separation technology, which has been dominated by polymer membranes. Recently, the inorganic membrane has been undergoing rapid development and innovation. Inorganic membranes have the advantage of resisting harsh chemical cleaning, high temperature and wear resistance, high chemical stability, long lifetime, and autoclavable. All of these outstanding properties made inorganic membranes good candidates to be used for water treatment and desalination applications. This paper is a state of the art review on the synthesis, development, and application of different inorganic membranes for water and wastewater treatment. The inorganic membranes reviewed in this paper include liquid membranes, dynamic membranes, various ceramic membranes, carbon based membranes, silica membranes, and zeolite membranes. A brief description of the different synthesis routes for the development of inorganic membranes for application in water industry is given and each synthesis rout is critically reviewed and compared. Thereafter, the recent studies on different application of inorganic membrane and their properties for water treatment and desalination in literature are critically summarized. It was reported that inorganic membranes despite their high synthesis cost, showed very promising results with high flux, full salt rejection, and very low or no fouling. PMID:29304024

  9. Inorganic Membranes: Preparation and Application for Water Treatment and Desalination

    Directory of Open Access Journals (Sweden)

    Ahmad Kayvani Fard

    2018-01-01

    Full Text Available Inorganic membrane science and technology is an attractive field of membrane separation technology, which has been dominated by polymer membranes. Recently, the inorganic membrane has been undergoing rapid development and innovation. Inorganic membranes have the advantage of resisting harsh chemical cleaning, high temperature and wear resistance, high chemical stability, long lifetime, and autoclavable. All of these outstanding properties made inorganic membranes good candidates to be used for water treatment and desalination applications. This paper is a state of the art review on the synthesis, development, and application of different inorganic membranes for water and wastewater treatment. The inorganic membranes reviewed in this paper include liquid membranes, dynamic membranes, various ceramic membranes, carbon based membranes, silica membranes, and zeolite membranes. A brief description of the different synthesis routes for the development of inorganic membranes for application in water industry is given and each synthesis rout is critically reviewed and compared. Thereafter, the recent studies on different application of inorganic membrane and their properties for water treatment and desalination in literature are critically summarized. It was reported that inorganic membranes despite their high synthesis cost, showed very promising results with high flux, full salt rejection, and very low or no fouling.

  10. Effect of stabilizers on the physico-chemical and sensory attributes ...

    African Journals Online (AJOL)

    SERVER

    2008-01-18

    Jan 18, 2008 ... a source of highly nutritive protein, energy from added cane sugar ... stability of the grain during storage, value of its product and ease of .... Effect of stabilizers on the solids and specific gravity of thermized yoghurt*+. Stabilize.

  11. Imparting chemical stability in nanoparticulate silver via a conjugated polymer casing approach.

    Science.gov (United States)

    Chang, Mincheol; Kim, Taejoon; Park, Hyun-Woo; Kang, Minjeong; Reichmanis, Elsa; Yoon, Hyeonseok

    2012-08-01

    Only limited information is available on the design and synthesis of functional materials for preventing corrosion of metal nanostructures. In the nanometer regime, even noble metals are subject to chemical attack. Here, the corrosion behavior of noble metal nanoparticles coated with a conjugated polymer nanolayer was explored for the first time. Specifically, electrochemical corrosion and sulfur tarnishing behaviors were examined for Ag-polypyrrole (PPy) core-shell nanoparticles using potentiodynamic polarization and spectrophotometric analysis, respectively. First, the Ag-PPy nanoparticles exhibited enhanced resistance to electrochemically induced corrosion compared to their exposed silver counterparts. Briefly, a neutral PPy shell provided the highest protection efficiency (75.5%), followed by sulfate ion- (61.3%) and dodecylbenzenesulfonate ion- (53.6%) doped PPy shells. However, the doping of the PPy shell with chloride ion induced an adverse effect (protection efficiency, -120%). Second, upon exposure to sulfide ions, the Ag-PPy nanoparticles preserved their morphology and colloidal stability while the bare silver analog underwent significant structural deformation. To further understand the function of the PPy shell as a protection layer for the silver core, the catalytic activity of the nanostructures was also evaluated. Using the reduction of 4-nitrophenol as a representative example of a catalytic reaction, the rate constant for that reduction using the PPy encased Ag nanoparticles was found to be 1.1 × 10(-3) s(-1), which is approximately 33% less than that determined for the parent silver. These results demonstrate that PPy can serve as both an electrical and chemical barrier for mitigating undesirable chemical degradation in corrosive environments, as well as provide a simple physical barrier to corrosive substances under appropriate conditions.

  12. New Polymeric Membranes for Organic Solvent Nanofiltration

    KAUST Repository

    Aburabie, Jamaliah

    2017-05-01

    The focus of this dissertation was the development, synthesis and modification of polymers for the preparation of membranes for organic solvent nanofiltration. High chemical stability in a wide range of solvents was a key requirement. Membranes prepared from synthesized polymers as well as from commercial polymers were designed and chemically modified to reach OSN requirements. A solvent stable thin-film composite (TFC) membrane is reported, which is fabricated on crosslinked polythiosemicarbazide (PTSC) as substrate. The membranes exhibited high fluxes towards solvents like THF, DMF and DMSO ranging around 20 L/m2 h at 5 bar with a MWCO of around 1000 g/mol. Ultrafiltration PTSC membranes were prepared by non-solvent induced phase separation and crosslinked with GPTMS. The crosslinking reaction was responsible for the formation of an inorganic-type-network that tuned the membrane pore size. The crosslinked membranes acquired high solvent stability in DMSO, DMF and THF with a MWCO above 1300 g/mol. Reaction Induced Phase Separation (RIPS) was introduced as a new method for the preparation of skinned asymmetric membranes. These membranes have two distinctive layers with different morphologies both from the same polymer. The top dense layer is composed of chemically crosslinked polymer chains while the bottom layer is a porous structure formed by non-crosslinked polymer chains. Such membranes were tested for vitamin B12 in solvents after either crosslinking the support or dissolving the support and fixing the freestanding membrane on alumina. Pebax® 1657 was utilized for the preparation of composite membranes by simple coating. Porous PAN membranes were coated with Pebax® 1657 which was then crosslinked using TDI. Crosslinked Pebax® membranes show high stability towards ethanol, propanol and acetone. The membranes were also stable in DMF once crosslinked PAN supports were used. Sodium alginate polymer was investigated for the preparation of thin film composite

  13. Polymer confined in membrane phases: influences on stability, structure and dynamics

    International Nuclear Information System (INIS)

    Javierre, Isabelle

    1999-01-01

    The addition of a hydrosoluble polymer to the different structures obtained with mixtures of water/surfactant/alcohol/oil alters the thermodynamic stability of microemulsion and lamellar phases. The reverse sponge phase disappears while one can observe the occurrence of a new phase, labelled L5, at intermediate polymer concentration. In polymer-'doped' solvent lamellar phase, the polymer induces an attractive contribution to the interaction between bilayers while in polymer-'doped' bilayers lamellar phase, the polymer increases the flexibility. The L5 phase exhibits symmetric sponge properties and furthermore presents very strong symmetry fluctuations. The relaxation of these fluctuations were experimentally evidenced for the first time. This unusual dynamic behaviour was confronted to the one of other sponge phases, in a large range of concentrations. (author) [fr

  14. Enhanced life of proton exchange membrane fuel cell catalysts using perfluorosulfonic acid stabilized carbon support

    International Nuclear Information System (INIS)

    Cheng Niancai; Mu Shichun; Chen Xiaojing; Lv Haifeng; Pan Mu; Edwards, Peter P.

    2011-01-01

    We report a new and simple solution to increase life of Pt/C catalysts using the proton-conducting polymer (perfluorosulfonic acid, PFSA) stabilized carbon support (denoted these catalysts as Pt/NFC catalysts) as compared to conventional Pt/C catalysts commonly used in PEM fuel cells. A high catalytic activity of the catalyst is observed by both CV (cyclic voltammetry) and ORR (oxygen reduction reaction) measurements. Especially, our own catalysts have a 60% better life as compared to Pt/C under electrochemically accelerated durability test conditions. The loss rate of electrochemical active area (ECA) for Pt/NFC catalysts is only 0.007 m 2 g -1 cycle -1 , compared to a value of 0.011 m 2 g -1 cycle -1 for Pt/C.

  15. Enhanced life of proton exchange membrane fuel cell catalysts using perfluorosulfonic acid stabilized carbon support

    Energy Technology Data Exchange (ETDEWEB)

    Cheng Niancai [State Key Laboratory of Advanced Technology for Materials Synthesis and Processing, Wuhan University of Technology, 430070 (China); Mu Shichun, E-mail: msc@whut.edu.c [State Key Laboratory of Advanced Technology for Materials Synthesis and Processing, Wuhan University of Technology, 430070 (China); Department of Chemistry, Inorganic Chemistry Laboratory, University of Oxford, South Parks Road, OX1 3QR (United Kingdom); Chen Xiaojing; Lv Haifeng; Pan Mu [State Key Laboratory of Advanced Technology for Materials Synthesis and Processing, Wuhan University of Technology, 430070 (China); Edwards, Peter P. [Department of Chemistry, Inorganic Chemistry Laboratory, University of Oxford, South Parks Road, OX1 3QR (United Kingdom)

    2011-02-01

    We report a new and simple solution to increase life of Pt/C catalysts using the proton-conducting polymer (perfluorosulfonic acid, PFSA) stabilized carbon support (denoted these catalysts as Pt/NFC catalysts) as compared to conventional Pt/C catalysts commonly used in PEM fuel cells. A high catalytic activity of the catalyst is observed by both CV (cyclic voltammetry) and ORR (oxygen reduction reaction) measurements. Especially, our own catalysts have a 60% better life as compared to Pt/C under electrochemically accelerated durability test conditions. The loss rate of electrochemical active area (ECA) for Pt/NFC catalysts is only 0.007 m{sup 2} g{sup -1} cycle{sup -1}, compared to a value of 0.011 m{sup 2} g{sup -1} cycle{sup -1} for Pt/C.

  16. Self-Assembling Peptide Surfactants A6K and A6D Adopt a-Helical Structures Useful for Membrane Protein Stabilization

    Directory of Open Access Journals (Sweden)

    Furen Zhuang

    2011-10-01

    Full Text Available Elucidation of membrane protein structures have been greatly hampered by difficulties in producing adequately large quantities of the functional protein and stabilizing them. A6D and A6K are promising solutions to the problem and have recently been used for the rapid production of membrane-bound G protein-coupled receptors (GPCRs. We propose that despite their short lengths, these peptides can adopt α-helical structures through interactions with micelles formed by the peptides themselves. These α-helices are then able to stabilize α-helical motifs which many membrane proteins contain. We also show that A6D and A6K can form β-sheets and appear as weak hydrogels at sufficiently high concentrations. Furthermore, A6D and A6K together in sodium dodecyl sulfate (SDS can form expected β-sheet structures via a surprising α-helical intermediate.

  17. Evaluation of physical stability and leachability of Portland Pozzolona Cement (PPC) solidified chemical sludge generated from textile wastewater treatment plants

    International Nuclear Information System (INIS)

    Patel, Hema; Pandey, Suneel

    2012-01-01

    Highlights: ► Stabilization/solidification of chemical sludge from textile wastewater treatment plants using Portland Pozzolona Cement (PPC) containing fly ash. ► Physical engineering (compressive strength and block density) indicates that sludge has potential to be reused for construction purpose after stabilization/solidification. ► Leaching of heavy metals from stabilized/solidified materials were within stipulated limits. ► There is a modification of microstructural properties of PPC with sludge addition as indicated by XRD and SEM patterns. - Abstract: The chemical sludge generated from the treatment of textile dyeing wastewater is a hazardous waste as per Indian Hazardous Waste Management rules. In this paper, stabilization/solidification of chemical sludge was carried out to explore its reuse potential in the construction materials. Portland Pozzolona Cement (PPC) was selected as the binder system which is commercially available cement with 10–25% fly ash interground in it. The stabilized/solidified blocks were evaluated in terms of unconfined compressive strength, block density and leaching of heavy metals. The compressive strength (3.62–33.62 MPa) and block density (1222.17–1688.72 kg/m 3 ) values as well as the negligible leaching of heavy metals from the stabilized/solidified blocks indicate that there is a potential of its use for structural and non-structural applications.

  18. Double-Layer Structured CO2 Adsorbent Functionalized with Modified Polyethyleneimine for High Physical and Chemical Stability.

    Science.gov (United States)

    Jeon, Sunbin; Jung, Hyunchul; Kim, Sung Hyun; Lee, Ki Bong

    2018-06-18

    CO 2 capture using polyethyleneimine (PEI)-impregnated silica adsorbents has been receiving a lot of attention. However, the absence of physical stability (evaporation and leaching of amine) and chemical stability (urea formation) of the PEI-impregnated silica adsorbent has been generally established. Therefore, in this study, a double-layer impregnated structure, developed using modified PEI, is newly proposed to enhance the physical and chemical stabilities of the adsorbent. Epoxy-modified PEI and diepoxide-cross-linked PEI were impregnated via a dry impregnation method in the first and second layers, respectively. The physical stability of the double-layer structured adsorbent was noticeably enhanced when compared to the conventional adsorbents with a single layer. In addition to the enhanced physical stability, the result of simulated temperature swing adsorption cycles revealed that the double-layer structured adsorbent presented a high potential working capacity (3.5 mmol/g) and less urea formation under CO 2 -rich regeneration conditions. The enhanced physical and chemical stabilities as well as the high CO 2 working capacity of the double-layer structured adsorbent were mainly attributed to the second layer consisting of diepoxide-cross-linked PEI.

  19. Antifoaming materials studies in G.S. (Girlder sulfide) heavy water plants. Chemical and thermical stability. Pt. 3

    International Nuclear Information System (INIS)

    Delfino, C.A.; Rojo, E.A.

    1988-01-01

    In Girlder sulfide (G.S.) heavy water plants hydrogen sulfide-water systems are inherentely foaming, so the adding of antifoaming materials is of great importance. These may be of high volatility, pyrolizable or chemically unstable in plant operation conditions (water and hydrogen sulfide at 2 MPa, up to 230 deg C). Five commercial surfactants were studied from the point of view of their chemical and thermical stability in order to select the most suitable. (Author) [es

  20. Modelling of cross-flow membrane contactors : Mass transfer with chemical reactions

    NARCIS (Netherlands)

    Dindore, V. Y.; Brilman, D. W. F.; Versteeg, G. F.

    2005-01-01

    Conventionally, carbon dioxide and hydrogen sulphide are absorbed using aqueous alkanolamines or carbonate solution in column type of equipment. However, in view of the unparallel advantages offered, the use of microporous hollow fiber membrane modules is an attractive alternative. In the present

  1. Comparative evaluation of haematological parameters and erythrocyte membrane stability in pregnant and lactating goats in different seasons of tropical Savannah.

    Science.gov (United States)

    Habibu, B; Makun, H J; Yaqub, L S; Buhari, H U; Aluwong, T; Kawu, M U

    2017-09-01

    Haematological parameters and erythrocyte osmotic fragility (EOF) are commonly used as indicators of health status and erythrocyte membrane integrity. Variations in haematological parameters and EOF in late gestation and early lactation during the cold-dry (CDS), hot-dry (HDS) and rainy (RAS) seasons were studied in sixty (n = 60) Red Sokoto goats (20 goats for each season). The ambient temperatures and temperature-humidity index recorded were higher in the afternoon hours of the HDS and RAS, but lower in the morning hours of the CDS as compared with the thermoneutral zone of goats. Results revealed that the pregnant goats had significantly (P goats, higher (P goats. The EOF was significantly higher during lactation than pregnancy in the CDS and HDS. Similarly, the magnitude of the left shift in fragiligram during the CDS was more marked in pregnant compared with lactating goats. During gestation, the CDS had lower (P goats during the CDS. In conclusion, seasonal variations exist in physiology of erythrocytes of goats during the peri-partum period, with an increase in PCV and RBC, but a decrease in haemoglobin parameters in pregnant compared with lactating goats during the RAS. Erythrocyte stability and membrane integrity were higher in pregnant than lactating goats, and also higher during the CDS than the HDS and RAS, irrespective of reproductive status. This information may be useful in the design of animal breeding and is of value in animal welfare, research, diagnosis and management of haematological conditions during the peri-partum period. Copyright © 2017 Elsevier Inc. All rights reserved.

  2. Sedimentation equilibrium of a small oligomer-forming membrane protein: effect of histidine protonation on pentameric stability.

    Science.gov (United States)

    Surya, Wahyu; Torres, Jaume

    2015-04-02

    Analytical ultracentrifugation (AUC) can be used to study reversible interactions between macromolecules over a wide range of interaction strengths and under physiological conditions. This makes AUC a method of choice to quantitatively assess stoichiometry and thermodynamics of homo- and hetero-association that are transient and reversible in biochemical processes. In the modality of sedimentation equilibrium (SE), a balance between diffusion and sedimentation provides a profile as a function of radial distance that depends on a specific association model. Herein, a detailed SE protocol is described to determine the size and monomer-monomer association energy of a small membrane protein oligomer using an analytical ultracentrifuge. AUC-ES is label-free, only based on physical principles, and can be used on both water soluble and membrane proteins. An example is shown of the latter, the small hydrophobic (SH) protein in the human respiratory syncytial virus (hRSV), a 65-amino acid polypeptide with a single α-helical transmembrane (TM) domain that forms pentameric ion channels. NMR-based structural data shows that SH protein has two protonatable His residues in its transmembrane domain that are oriented facing the lumen of the channel. SE experiments have been designed to determine how pH affects association constant and the oligomeric size of SH protein. While the pentameric form was preserved in all cases, its association constant was reduced at low pH. These data are in agreement with a similar pH dependency observed for SH channel activity, consistent with a lumenal orientation of the two His residues in SH protein. The latter may experience electrostatic repulsion and reduced oligomer stability at low pH. In summary, this method is applicable whenever quantitative information on subtle protein-protein association changes in physiological conditions have to be measured.

  3. Study on stability of labeled yttrium-90 with lipiodol by chemical extraction for liver cancer

    International Nuclear Information System (INIS)

    Mu, P.Y.; Jiang, X.L.; Chen, J.; Zhu, Y.J.

    2005-01-01

    Liver cancer, particularly hepatocellular carcinoma, is one of the most common malignant diseases in many developed and developing countries. It is also one of the most common diseases endangering the people's lives and health heavily. Surgery is very effective in early-stage patients. Unfortunately, there is less than 10% of the patients with hepatocellular carcinoma fitting for surgical therapy. Instead of surgical therapy, other methods are considered for patients in whom surgery may not work well. Systemic administration of chemotherapeutic agents is not often considered in liver cancer patients, due to discouraging result and adverse side effects. Also, hepatocellular carcinoma is not keen on usual radioactive therapy. However, method of inner interventional radioactive nuclide is a potential way to cure liver tumors. Hepatocellular carcinoma would be cured with inner interventional radioactive nuclide, which is a hot topic in experimental research on hepatocellular carcinoma at home and abroad. The purpose of the study is to label Yttrium-90 with lipiodol by means of the chemical extraction method and research the stability of labeled Yttrium-90 ( 90 Y-P204-Lipiodol) in serum of a newly-born cattle and human's blood. We chose to label steady yttrium with lipiodol, because radioactive yttrium has great nuclear character for liver cancer, yttrium-90 can eradiate pure β radial, and it's half time is 64 hours. Average energy of it is 0.93 Mev, the highest energy is 2.27 Mev. Yttrium-90 can be labeled with lipiodol by means of the chemical extraction method, which is mature in chemical techniques, combined with method of radioactive nuclide labeled in. nuclear medicine. At first, yttrium-90 is extracted in certain condition(pH, temperature, whisk time, whisk frequency, etc ) after adding yttrium-90 solution. We use some distilled water to balance the labeled organic phase twice, and test the stability of labeled yttrium-90 in serum of a newly-born cattle and

  4. Iron-phosphate-based chemically bonded phosphate ceramics for mixed waste stabilization

    International Nuclear Information System (INIS)

    Wagh, A.S.; Jeong, S.Y.; Singh, D.

    1997-01-01

    In an effort to develop chemically bonded phosphate ceramics for mixed waste stabilization, a collaborative project to develop iron-phosphate based ceramics has been initiated between Argonne National Laboratory and the V. G. Khlopin Radium Institute in St. Petersburg, Russia. The starter powders are oxides of iron that are generated as inexpensive byproduct materials in the iron and steel industry. They contain iron oxides as a mixture of magnetite (Fe 3 O 4 ) and haematite (Fe 2 O 3 ). In this initial phase of this project, both of these compounds were investigated independently. Each was reacted with phosphoric acid solution to form iron phosphate ceramics. In the case of magnetite, the reaction was rapid. Adding ash as the waste component containing hazardous contaminants resulted in a dense and hard ceramic rich in glassy phase. On the other hand, the reaction of phosphoric acid solution with a mixture of haematite and ash waste contaminated with cesium and americium was too slow. Samples had to be molded under pressure. They were cured for 2-3 weeks and then hardened by heating at 350 degrees C for 3 h. The resulting ceramics in both cases were subjected to physical tests for measurement of density, open porosity, compression strength, phase analyses using X-ray diffraction and differential thermal analysis, and leaching tests using toxicity characteristic leaching procedure (TCLP) and ANS 16.1 with 7 days of leaching. Using the preliminary information obtained from these tests, we evaluated these materials for stabilization of Department of Energy's mixed waste streams

  5. In-line formation of chemically cross-linked P84® co-polyimide hollow fibre membranes for H2/CO2 separation

    KAUST Repository

    Choi, Seung Hak; Jansen, Johannes C.; Tasselli, Franco; Barbieri, Giuseppe; Drioli, Enrico

    2010-01-01

    In this study, chemically cross-linked asymmetric P84® co-polyimide hollow fibre membranes with enhanced separation performance were fabricated, using a dry-wet spinning process with an innovative in-line cross-linking step. The chemical

  6. Nafion-TiO2 composite DMFC membranes: physico-chemical properties of the filler versus electrochemical performance

    International Nuclear Information System (INIS)

    Baglio, V.; Arico, A.S.; Di Blasi, A.; Antonucci, V.; Antonucci, P.L.; Licoccia, S.; Traversa, E.; Fiory, F. Serraino

    2005-01-01

    TiO 2 nanometric powders were prepared via a sol-gel procedure and calcined at various temperatures to obtain different surface and bulk properties. The calcined powders were used as fillers in composite Nafion membranes for application in high temperature direct methanol fuel cells (DMFCs). The powder physico-chemical properties were investigated by X-ray diffraction (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS) and pH measurements. The observed characteristics were correlated to the DMFC electrochemical behaviour. Analysis of the high temperature conductivity and DMFC performance reveals a significant influence of the surface characteristics of the ceramic oxide, such as oxygen functional groups and surface area, on the membrane electrochemical behaviour. A maximum DMFC power density of 350 mW cm -2 was achieved under oxygen feed at 145 deg. C in a pressurized DMFC (2.5 bar, anode and cathode) equipped with TiO 2 nano-particles based composite membranes

  7. Chemical de-conjugation for investigating the stability of small molecule drugs in antibody-drug conjugates.

    Science.gov (United States)

    Chen, Tao; Su, Dian; Gruenhagen, Jason; Gu, Christine; Li, Yi; Yehl, Peter; Chetwyn, Nik P; Medley, Colin D

    2016-01-05

    Antibody-drug conjugates (ADCs) offer new therapeutic options for advanced cancer patients through precision killing with fewer side effects. The stability and efficacy of ADCs are closely related, emphasizing the urgency and importance of gaining a comprehensive understanding of ADC stability. In this work, a chemical de-conjugation approach was developed to investigate the in-situ stability of the small molecule drug while it is conjugated to the antibody. This method involves chemical-mediated release of the small molecule drug from the ADC and subsequent characterization of the released small molecule drug by HPLC. The feasibility of this technique was demonstrated utilizing a model ADC containing a disulfide linker that is sensitive to the reducing environment within cancer cells. Five reducing agents were screened for use in de-conjugation; tris(2-carboxyethyl) phosphine (TCEP) was selected for further optimization due to its high efficiency and clean impurity profile. The optimized de-conjugation assay was shown to have excellent specificity and precision. More importantly, it was shown to be stability indicating, enabling the identification and quantification of the small molecule drug and its degradation products under different formulation pHs and storage temperatures. In summary, the chemical de-conjugation strategy demonstrated here offers a powerful tool to assess the in-situ stability of small molecule drugs on ADCs and the resulting information will shed light on ADC formulation/process development and storage condition selection. Copyright © 2015 Elsevier B.V. All rights reserved.

  8. The Effect of Membrane Environment on Surfactant Protein C Stability Studied by Constant-pH Molecular Dynamics.

    Science.gov (United States)

    Carvalheda, Catarina A; Campos, Sara R R; Baptista, António M

    2015-10-26

    Pulmonary surfactant protein C (SP-C) is a small peptide with two covalently linked fatty acyl chains that plays a crucial role in the formation and stabilization of the pulmonary surfactant reservoirs during the compression and expansion steps of the respiratory cycle. Although its function is known to be tightly related to its highly hydrophobic character and key interactions maintained with specific lipid components, much is left to understand about its molecular mechanism of action. Also, although it adopts a mainly helical structure while associated with the membrane, factors as pH variation and deacylation have been shown to affect its stability and function. In this work, the conformational behavior of both the acylated and deacylated SP-C isoforms was studied in a DPPC bilayer under different pH conditions using constant-pH molecular dynamics simulations. Our findings show that both protein isoforms are remarkably stable over the studied pH range, even though the acylated isoform exhibits a labile helix-turn-helix motif rarely observed in the other isoform. We estimate similar tilt angles for the two isoforms over the studied pH range, with a generally higher degree of internalization of the basic N-terminal residues in the deacylated case, and observe and discuss some protonation-conformation coupling effects. Both isoforms establish contacts with the surrounding lipid molecules (preferentially with the sn-2 ester bonds) and have a local effect on the conformational behavior of the surrounding lipid molecules, the latter being more pronounced for acylated SP-C.

  9. Study of glucoamylase immobilization in butadiene nitrile latex membrane

    International Nuclear Information System (INIS)

    Miller, E.

    1992-01-01

    Attempts have been undetaken to immobilize glucoamylaze by means of butadiene nitrile latex in the presence of a chemical initiator and 60 Co γ-radiation. The activity, stability of conjugates in the membrane and permeability of oxygen in these membranes were determined. (author) 14 refs.; 5 figs

  10. A review of the chemical and physical mechanisms of the storage stability of fast pyrolysis bio-oils

    Energy Technology Data Exchange (ETDEWEB)

    Diebold, J.P.

    1999-01-27

    Understanding the fundamental chemical and physical aging mechanisms is necessary to learn how to produce a bio-oil that is more stable during shipping and storage. This review provides a basis for this understanding and identifies possible future research paths to produce bio-oils with better storage stability.

  11. Comparative leaching of six toxic metals from raw and chemically stabilized MSWI fly ash using citric acid.

    Science.gov (United States)

    Wang, Huawei; Fan, Xinxiu; Wang, Ya-Nan; Li, Weihua; Sun, Yingjie; Zhan, Meili; Wu, Guizhi

    2018-02-15

    The leaching behavior of six typical toxic metals (Pb, Zn, Cr, Cd, Cu and Ni) from raw and chemically stabilized (phosphate and chelating agent) municipal solid waste incineration (MSWI) fly ash were investigated using citric acid. Leaching tests indicated that phosphate stabilization can effectively decrease the leaching of Zn, Cd and Cr; whereas chelating agent stabilization shows a strong ability to lower the release of Pb, Cd and Cu, but instead increases the solubility of Zn and Cr at low pH conditions. Sequential extraction results suggested that the leaching of Pb, Zn and Cd in both the stabilized MSWI fly ash samples led to the decrease in Fe/Mn oxide fraction and the increase in exchangeable and carbonate fractions. The leaching of Cr was due to the decrease in exchangeable, carbonate and Fe/Mn oxide fractions in phosphate-stabilized and chelating agent-stabilized MSWI fly ash. The leaching of Cu in both stabilized MSWI fly ash was greatly ascribed to the decrease in Fe/Mn oxide and oxidisable fractions. Moreover, predicted curves by geochemical model indicated that both stabilized MSWI fly ash have the risk of releasing toxic metals under strong acid environment. Copyright © 2017 Elsevier Ltd. All rights reserved.

  12. The Influence of Chemically Modified Potato Maltodextrins on Stability and Rheological Properties of Model Oil-in-Water Emulsions

    Directory of Open Access Journals (Sweden)

    Karolina Pycia

    2018-01-01

    Full Text Available The aim of this study was to determine the effect of the maltodextrins prepared from chemically modified starches (crosslinked, stabilized, crosslinked and stabilized on the stability and rheological properties of model oil-in-water (o/w emulsions. Based on the obtained results, it was concluded that emulsion stability depended on hydrolysates dextrose equivalent (DE value. Maltodextrin with the lowest degree of depolymerization effectively stabilized the dispersed system, and the effectiveness of this action depended on the maltodextrin type and concentration. Addition of distarch phosphate-based maltodextrin stabilized emulsion at the lowest applied concentration, and the least effective was maltodextrin prepared from acetylated starch. Emulsions stabilized by maltodextrins (DE 6 prepared from distarch phosphate and acetylated distarch adipate showed the predominance of the elastic properties over the viscous ones. Only emulsion stabilized by maltodextrin prepared from distarch phosphate (E1412 revealed the properties of strong gel. Additionally, the decrease in emulsions G′ and G″ moduli values, combined with an increase in the value of DE maltodextrins, was observed.

  13. Liquid Membranes as a Tool for Chemical Speciation of Metals in Natural Waters: Organic and Inorganic Complexes of Nickel.

    Science.gov (United States)

    Vergel, Cristina; Mendiguchía, Carolina; Moreno, Carlos

    2018-04-15

    The different species of nickel present in natural waters exhibit different transport behaviour through bulk liquid membranes (BLMs). This fact has been used to design and optimise a separation/pre-concentration system applicable to separate labile and non-labile nickel fractions. A hydrazone derivative-1,2-cyclohexanedione bis-benzoyl-hydrazone (1,2-CHBBH) dissolved in toluene/dimethyl formamide (2% DMF)-was used as a chemical carrier of nickel species, from an aqueous source solution (sample) to a receiving acidic solution. Both chemical and hydrodynamic conditions controlling the transport system were studied and optimised. Under optimum conditions, variations in the transport of nickel ions as a function of organic (humic acids) and inorganic (chloride ions) ligands were studied. Relationships between the permeability coefficient ( P ) or recovery efficiency (%R) and the concentrations of ligands and nickel species were analysed using Winhumic V software. A negative correlation between P and the concentration of organic nickel complexes was found, suggesting that only labile nickel species are transported through the liquid membrane, with non-labile complexes remaining in the water sample; allowing for their separation and subsequent quantification in natural waters.

  14. Liquid Membranes as a Tool for Chemical Speciation of Metals in Natural Waters: Organic and Inorganic Complexes of Nickel

    Directory of Open Access Journals (Sweden)

    Cristina Vergel

    2018-04-01

    Full Text Available The different species of nickel present in natural waters exhibit different transport behaviour through bulk liquid membranes (BLMs. This fact has been used to design and optimise a separation/pre-concentration system applicable to separate labile and non-labile nickel fractions. A hydrazone derivative—1,2-cyclohexanedione bis-benzoyl-hydrazone (1,2-CHBBH dissolved in toluene/dimethyl formamide (2% DMF—was used as a chemical carrier of nickel species, from an aqueous source solution (sample to a receiving acidic solution. Both chemical and hydrodynamic conditions controlling the transport system were studied and optimised. Under optimum conditions, variations in the transport of nickel ions as a function of organic (humic acids and inorganic (chloride ions ligands were studied. Relationships between the permeability coefficient (P or recovery efficiency (%R and the concentrations of ligands and nickel species were analysed using Winhumic V software. A negative correlation between P and the concentration of organic nickel complexes was found, suggesting that only labile nickel species are transported through the liquid membrane, with non-labile complexes remaining in the water sample; allowing for their separation and subsequent quantification in natural waters.

  15. Chemical stability and in chemico reactivity of 24 fragrance ingredients of concern for skin sensitization risk assessment.

    Science.gov (United States)

    Avonto, Cristina; Wang, Mei; Chittiboyina, Amar G; Vukmanovic, Stanislav; Khan, Ikhlas A

    2018-02-01

    Twenty-four pure fragrance ingredients have been identified as potential concern for skin sensitization. Several of these compounds are chemically unstable and convert into reactive species upon exposure to air or light. In the present work, a systematic investigation of the correlation between chemical stability and reactivity has been undertaken. The compounds were subjected to forced photodegradation for three months and the chemical changes were studied with GC-MS. At the end of the stability study, two-thirds of the samples were found to be unstable. The generation of chemically reactive species was investigated using the in chemico HTS-DCYA assay. Eleven and fourteen compounds were chemically reactive before and after three months, respectively. A significant increase in reactivity upon degradation was found for isoeugenol, linalool, limonene, lyral, citronellol and geraniol; in the same conditions, the reactivity of hydroxycitronellal decreased. The non-reactive compounds α-isomethyl ionone, benzyl alcohol, amyl cinnamal and farnesol became reactive after photo-oxidative degradation. Overall, forced degradation resulted in four non-reactive fragrance compounds to display in chemico thiol reactivity, while ten out of 24 compounds remained inactive. Chemical degradation does not necessarily occur with generation of reactive species. Non-chemical activation may be involved for the 10 stable unreactive compounds. Copyright © 2017 Elsevier Ltd. All rights reserved.

  16. Influence of N-Oxide Introduction on the Stability of Nitrogen-Rich Heteroaromatic Rings: A Quantum Chemical Study.

    Science.gov (United States)

    Yuan, Jia; Long, Xinping; Zhang, Chaoyang

    2016-12-01

    N-Oxidization is an important strategy for enhancing the density and energy of energetic materials. Nevertheless, the influence of N + -O - introduction on molecular stability remains relatively unknown. Thus, the present work comprehensively studied 102 basic N-rich ring structures, including azoles, furazans, and azines, as well as their N-oxides by quantum chemical calculations. The introduction of N + -O - weakens molecular stability in most cases because the process elongates chemical bonds, decreases ring aromaticity, narrows the gaps between the highest occupied and lowest unoccupied molecular orbitals, and increases the photochemical reactivity. Besides, the easy H transfer to the neighboring O atom, which forms a N-OH isomer in azoles, renders the stabilization by N-oxide introduction ineffective. However, N-oxide introduction can enhance the molecular stability of 1,2,3,4-tetrazine-1,3-dioxide and tetrazino-tetrazine 1,3,6,8-tetraoxide by promoting σ-π separation and relieving lone-pair repulsion. Moreover, the alternate arrangement of positive and negative charges is another factor stabilizing the 1,2,3,4-tetrazine ring by 1,3-dioxidation. Finally, we assess the accessibility of N-oxidized azoles and azines by regarding N 2 O and H 2 O 2 as oxidizers. We find that all the oxidations were exothermic, thermodynamically spontaneous, and kinetically feasible. After an overall evaluation, we propose 19 N-oxides as basic structures for high-energy materials with considerable stability.

  17. Physical and chemical stability of expired fixed dose combination artemether-lumefantrine in uncontrolled tropical conditions

    Directory of Open Access Journals (Sweden)

    Hess Kimberly

    2009-02-01

    Full Text Available Abstract Background New artemisinin combination therapies pose difficulties of implementation in developing and tropical settings because they have a short shelf-life (two years relative to the medicines they replace. This limits the reliability and cost of treatment, and the acceptability of this treatment to health care workers. A multi-pronged investigation was made into the chemical and physical stability of fixed dose combination artemether-lumefantrine (FDC-ALU stored under heterogeneous, uncontrolled African conditions, to probe if a shelf-life extension might be possible. Methods Seventy samples of expired FDC-ALU were collected from private pharmacies and malaria researchers in seven African countries. The samples were subjected to thin-layer chromatography (TLC, disintegration testing, and near infrared Raman spectrometry for ascertainment of active ingredients, tablet integrity, and chemical degradation of the tablet formulation including both active ingredients and excipients. Results Seventy samples of FDC-ALU were tested in July 2008, between one and 58 months post-expiry. 68 of 70 (97% samples passed TLC, disintegration and Raman spectrometry testing, including eight samples that were post-expiry by 20 months or longer. A weak linear association (R2 = 0.33 was observed between the age of samples and their state of degradation relative to brand-identical samples on Raman spectrometry. Sixty-eight samples were retested in February 2009 using Raman spectrometry, between eight and 65 months post-expiry. 66 of 68 (97% samples passed Raman spectrometry retesting. An unexpected observation about African drug logistics was made in three batches of FDC-ALU, which had been sold into the public sector at concessional pricing in accordance with a World Health Organization (WHO agreement, and which were illegally diverted to the private sector where they were sold for profit. Conclusion The data indicate that FDC-ALU is chemically and

  18. Nutritional Profile and Chemical Stability of Pasta Fortified with Tilapia (Oreochromis niloticus) Flour.

    Science.gov (United States)

    Monteiro, Maria Lúcia G; Mársico, Eliane T; Soares, Manoel S; Magalhães, Amanda O; Canto, Anna Carolina V C S; Costa-Lima, Bruno R C; Alvares, Thiago S; Conte, Carlos A

    2016-01-01

    Physicochemical parameters of pasta enriched with tilapia (Oreochromis niloticus) flour were investigated. Five formulations were prepared with different concentrations of tilapia flour as partial substitute of wheat flour: pasta without tilapia flour (PTF0%), pasta with 6% (PTF6%), 12% (PTF12%), 17% (PTF17%), and 23% (PTF23%) of tilapia flour. The formulations were assessed for proximate composition, fatty acid and amino acid profile on day 1 whereas, instrumental color parameters (L*, a* and b* values), pH, water activity (aw), and lipid and protein oxidation were evaluated on days 1, 7, 14, and 21 of storage at 25°C. Fortification with tilapia flour increased (p pasta with tilapia flour decreased (p pasta containing 12%, 17%, and 23% of tilapia flour than their counterparts, and the storage promoted an increase (p pasta with 6% of tilapia flour has the potential to be a technological alternative to food industry for the nutritional enrichment of traditional pasta with negligible negative effects on the chemical stability of the final product during 21 days at 25°C.

  19. Energetics and stability of azulene: From experimental thermochemistry to high-level quantum chemical calculations

    International Nuclear Information System (INIS)

    Sousa, Clara C.S.; Matos, M. Agostinha R.; Morais, Victor M.F.

    2014-01-01

    Highlights: • Experimental standard molar enthalpy of formation, sublimation azulene. • Mini-bomb combustion calorimetry, sublimation Calvet microcalorimetry. • High level composite ab initio calculations. • Computational estimate of the enthalpy of formation of azulene. • Discussion of stability and aromaticity of azulene. - Abstract: The standard (p 0 = 0.1 MPa) molar enthalpy of formation for crystalline azulene was derived from the standard molar enthalpy of combustion, in oxygen, at T = 298.15 K, measured in a mini-bomb combustion calorimeter (aneroid isoperibol calorimeter) and the standard molar enthalpy of sublimation, at T = 298.15 K, measured by Calvet microcalorimetry. From these experiments, the standard molar enthalpy of formation of azulene in the gaseous phase at T = 298.15 K was calculated. In addition, very accurate quantum chemical calculations at the G3 and G4 composite levels of calculation were conducted in order to corroborate our experimental findings and further clarify and establish the definitive standard enthalpy of formation of this interesting non-benzenoid hydrocarbon

  20. Arsenic stability and mobilization in soil at an amenity grassland overlying chemical waste (St. Helens, UK)

    Energy Technology Data Exchange (ETDEWEB)

    Hartley, William [School of Biological and Earth Sciences, Liverpool John Moores University, Byrom Street, Liverpool L3 3AF (United Kingdom)], E-mail: w.hartley@ljmu.ac.uk; Dickinson, Nicholas M. [School of Biological and Earth Sciences, Liverpool John Moores University, Byrom Street, Liverpool L3 3AF (United Kingdom); Clemente, Rafael [Department of Soil and Water Conservation and Organic Waste Management, Centro de Edafologia y Biologia Aplicada del Segura, CSIC, Apartado 4195, 30080 Murcia (Spain); French, Christopher [School of Biological and Earth Sciences, Liverpool John Moores University, Byrom Street, Liverpool L3 3AF (United Kingdom); Piearce, Trevor G. [Biological Sciences Division, Lancaster Environment Centre, Lancaster University, Lancaster LA1 4YQ (United Kingdom); Sparke, Shaun; Lepp, Nicholas W. [School of Biological and Earth Sciences, Liverpool John Moores University, Byrom Street, Liverpool L3 3AF (United Kingdom)

    2009-03-15

    A 6.6 ha grassland, established on a former chemical waste site adjacent to a residential area, contains arsenic (As) in surface soil at concentrations 200 times higher than UK Soil Guideline Values. The site is not recognized as statutory contaminated land, partly on the assumption that mobility of the metalloid presents a negligible threat to human health, groundwater and ecological receptors. Evidence for this is evaluated, based on studies of the effect of organic (green waste compost) and inorganic (iron oxides, lime and phosphate) amendments on As fractionation, mobility, plant uptake and earthworm communities. Arsenic mobility in soil was low but significantly related to dissolved organic matter and phosphate, with immobilization associated with iron oxides. Plant uptake was low and there was little apparent impact on earthworms. The existing vegetation cover reduces re-entrainment of dust-blown particulates and pathways of As exposure via this route. Minimizing risks to receptors requires avoidance of soil exposure, and no compost or phosphate application. - Stabilization of alkali industry waste requires careful management to minimise soil arsenic mobilization and dispersal to the wider environment.

  1. A conceptual chemical solidification/stabilization system to remediate radioactive raffinate sludge

    International Nuclear Information System (INIS)

    Carpenter, D.J.; Ansted, J.P.; Foldyna, J.T.

    1994-01-01

    Past operations at the U.S. Department of Energy's (DOE) Weldon Spring, Missouri, Superfund Site included the manufacture of nitroaromatic-based munitions and the production of uranium and thorium metal from ore concentrates. These operations generated a large quantity of diverse contaminated waste media including raffinate sludge, soil, sediment, and building debris. These various waste media are contaminated with varying amounts of radionuclides nitroaromatics, metals, metalloids, non-metals, polychlorinated biphenyls (PCBs) and asbestos. The volumes and diversity of contaminants and waste media pose significant challenges in identifying applicable remedial technologies, particularly for the excavation and treatment of the water-rich raffinate sludge. This paper presents the results of comprehensive efforts to develop a conceptual chemical solidification/stabilization (CSS) system to treat a variety of waste media. The emphasis of this paper is the treatment of a water-rich refractory raffinate sludge and site contaminated soils both radioactive and nonradioactive. The conceptual system design includes raffinate sludge excavation, dewatering, and CSS processing (reagent selection and formulation, reagent and waste storage and metering, and product mixing). Many innovations were incorporated into the design, producing a system that can process the various waste types. Additionally, the radioactive and hazardous constituents are sufficiently immobilized to allow the secured disposal in a waste cell of the treated product. The conceptual CSS system can also produce a variety of treated product types, ranging from a monolithic form to a compactible soil-like medium. The advantages of this system flexibility are also presented

  2. Impact of polyethylene glycol on proline and membrane stability index for water stress regime in tomato (Solanum lycopersicum)

    International Nuclear Information System (INIS)

    George, S.; Jatoi, S.A.; Siddiqui, S.U.

    2015-01-01

    Drought is one of the most important constraints worldwide for crop growth including tomato. It adversely affects germination and seedling that ultimately reduces crop development and economic yield. Polyethylene glycol (PEG) gives an indication to abiotic stresses and has been used throughout world in various crops for successful screening and breeding against stresses. Contrarily proline protects plant tissues against stress through preventing molecular denaturation, scavenges reactive oxygen species and interacts with phospholipids. Present paper presents the results on PEG and proline estimation in tomato. The PEG screening reduced the experimental material and finally 20 genotypes (6232, 6233, 6234, 10584, 10587, 17889, 17902, 17904, 19288, 19289, 19290, 19291, 19893, Avinash-2, Feston, Nagina, Punjab Chohara, Ratan and T-4) from diverse origin were investigated for proline estimation, chlorophyll contents and membrane stability index that gave a clear reference for drought tolerance in tomato. All the techniques (PEG, Proline, MSI) related to drought screening were employed and their interactive interpretation will enable us to design future breeding strategies for tomato development under drought that is still a dream for man. Among 20 genotypes, 19291 possessed the highest proline contents hence was tolerant to drought conditions, although needs verification under actual drought for adaptability and yield potential. High MSI under stress was observed for Punjab Chuhara, Chuhara, Avinash-2, Ratan, 19893, 19291 and 6233. (author)

  3. Physico-chemical and mineralogical properties influencing water-stability of aggregates of some Italian surface soils

    International Nuclear Information System (INIS)

    Mbagwu, J.S.C.; Bazzoffi, P.; Unamba Oparah, I.

    1994-06-01

    A laboratory study was conducted to determine the relationship between physical, chemical and mineralogical properties of some surface soils (developed in north central Italy) and the stability of their aggregates to water. The index of stability used is the mean-weight diameter of water-stable aggregates (MWD). The ratio of total sand to clay which correlated negatively with MWD (r=-0.638) is the physical property which explained most of the variability in aggregate stability. The chemical properties which correlated best with aggregate stability are FeO (r=0.671), CaO (R=0.635), CaCO 3 (r=0.651) and SiO 2 (r=-0.649). Feldspar, chlorite and calcite are the minerals which influence MWD most, with respective ''r'' values of -0.627, 0.588 and 0.550. The best-fit model developed from soil physical properties explained 59% of the variation in MWD with a standard error of 0.432, that developed from chemical properties explained 97% of the variation in MWD with a standard error of 0.136, whereas the model developed from mineralogical properties explained 78% of the variation in MWD with a standard error of 0.222. Also the closest relationship between measured and model-predicted MWD was obtained with the chemical properties-based model (r=0.985), followed by the mineralogical properties-based model (r=0.884) and then the physical properties-based model (r=0.656). This indicates that the most reliable inference on the stability of these soils in water can be made from a knowledge of the amount and composition of their chemical constituents. (author). 32 refs, 1 fig., 9 tabs

  4. Ceramic membrane fouling during ultrafiltration of oil/water emulsions: Roles played by stabilization surfactants of oil droplets

    KAUST Repository

    Lu, Dongwei; Zhang, Tao; Ma, Jun

    2015-01-01

    of classical fouling models, and analysis of organic components rejected by the membrane. Furthermore, this mechanism was also verified by the existence of a steric effect and demulsification effect. Our finding suggests that ceramic membrane oppositely charged

  5. Radiation and chemical stability of 2-deoxy-2-[18F]fluoro-D-glucose radiopharmaceutical

    International Nuclear Information System (INIS)

    Buriova, M.

    2004-07-01

    molecules association with formate anion HCOO - and also for negative ions of deprotonised molecules. All acids appeared in the form of their lactones. FDG and GLC exhibited tendency for formation of a mixed associate charged by HCOO - anion. On the amine bond silica gel HPTLC column, FDG is poorly separated from fluoride, which even in presence of Kryptofix 2.2.2 remains on the start like on the silica gel layer. The last parathion is to be used as a standard technique for [ 18 F]F - assay. At LC-MS Kryptofix provides a very well measurable signals of associates with NH 4 + a H + ions in positive mode of ESI MS. Sensitivity of the ESI MS detector towards sugars is for three orders of magnitude higher than the refraction index detector, which is used for routine analysis, and enables estimation of molar activity of non-carrier-added 2-[ 18 F]FDG. The results of quantitative LC/MS analysis and high-efficient radiometric detector were used for specific activity of 2-[ 18 F]FDG assessment. Concentration of FDG carrier in 2-[ 18 F]FDG preparation was found to be 6 mg.dm -3 and in combination with a radiometric detector the specific activity 6.6 GBq.μmol -1 of 2-[ 18 F]FDG was found. The molar activity of carrier-free ( 18 F)FDG is 63 TBq.μmol -1 , and for good quality of bio-specific ligands at PET it is supposed to be minimally 1 kBq.fmol -1 . Radiation and chemical stability of 2-deoxy-2-[ 18 F]fluoro-D-glucose, and its comparison with glucose at oxidation by Fenton's reagent and autoradiolysis was found. The main oxidation products of FDG and glucose by Fenton's reagent were arabonic acid at 14-23% yield, gluconic acid 12%, both glucuronic acid and arabinose at 5%. In case of FDG among the principal products 2-fluorgluconic acid and 2-fluorgluconic acid by 2.7 % and 4% yields respectively were identified. The dose rates in real solutions of 2-[ 18 F]FDG, as well as the radiation-chemical yields of radioactive (fluorinated), but also further products of autoradiolysis of 2

  6. Dense ceramic membranes based on ion conducting oxides

    International Nuclear Information System (INIS)

    Fontaine, M.L.; Larring, Y.; Bredesen, R.; Norby, T.; Grande, T.

    2007-01-01

    This chapter reviews the recent progress made in the fields of high temperature oxygen and hydrogen separation membranes. Studies of membranes for oxygen separation are mainly focusing on materials design to improve flux, and to lesser extent, related to stability issues. High oxygen fluxes satisfying industrial requirements can be obtained but, for many materials, the surface exchange rate is limiting the performance. The current status on electrolyte-type and mixed proton and electron conducting membranes is outlined, highlighting materials with improved stability in typical applications as solid oxide fuel cell technology and gas separation. In our presentation more fundamental aspects related to transport properties, chemical and mechanical stability of membrane materials are also treated. It is concluded that a significantly better understanding of the long term effects of operation in chemical gradients is needed for these types of membrane materials. (authors)

  7. Optimization of O3 as Pre-Treatment and Chemical Enhanced Backwashing in UF and MF Ceramic Membranes for the Treatment of Secondary Wastewater Effluent and Red Sea Water

    KAUST Repository

    Herrera, Catalina

    2011-01-01

    Ceramic membranes have proven to have many advantages over polymeric membranes. Some of these advantages are: resistance against extreme pH, higher permeate flux, less frequent chemical cleaning, excellent backwash efficiency and longer lifetime

  8. Oxygen Permeation and Stability Study of (La0.6Ca0.4)0.98(Co0.8Fe0.2)O3-δ Membranes

    DEFF Research Database (Denmark)

    Salehi, Mehdi; Søgaard, Martin; Esposito, Vincenzo

    2017-01-01

    ) was tested. A small decrease in the flux was observed over 48 h in CO2 at 850 °C. SEM examinations of the cross-section of the tested membrane showed that the Ca rich phase in the membrane showed a tendency to migrate to the feed side. Whereas the material shows a CO2 stability superior to that of Sr or Ba......The perovskite-type oxide (La0.6Ca0.4)0.98(Co0.8Fe0.2)O3-δ (LCCF) was investigated for use as oxygen separation membrane. A 25 µm thick dense membrane on a porous LCCF support with a thickness of around 175 µm was prepared by a tape casting and lamination process. The optimum sintering temperature...... of the component was established to be 1050 °C by analysis of microstructures of membranes sintered at different temperatures. Scanning electron microscopy (SEM) examination of cross-sections of the sintered membrane showed that it consisted of two phases, the main phase being enriched in calcium (Ca) and depleted...

  9. The pH-dependent long-term stability of an amorphous manganese oxide in smelter-polluted soils: implication for chemical stabilization of metals and metalloids.

    Science.gov (United States)

    Ettler, Vojtěch; Tomášová, Zdeňka; Komárek, Michael; Mihaljevič, Martin; Šebek, Ondřej; Michálková, Zuzana

    2015-04-09

    An amorphous manganese oxide (AMO) and a Pb smelter-polluted agricultural soil amended with the AMO and incubated for 2 and 6 months were subjected to a pH-static leaching procedure (pH 3-8) to verify the chemical stabilization effect on metals and metalloids. The AMO stability in pure water was pH-dependent with the highest Mn release at pH 3 (47% dissolved) and the lowest at pH 8 (0.14% dissolved). Secondary rhodochrosite (MnCO3) was formed at the AMO surfaces at pH>5. The AMO dissolved significantly less after 6 months of incubation. Sequential extraction analysis indicated that "labile" fraction of As, Pb and Sb in soil significantly decreased after AMO amendment. The pH-static experiments indicated that no effect on leaching was observed for Cd and Zn after AMO treatments, whereas the leaching of As, Cu, Pb and Sb decreased down to 20%, 35%, 7% and 11% of the control, respectively. The remediation efficiency was more pronounced under acidic conditions and the time of incubation generally led to increased retention of the targeted contaminants. The AMO was found to be a promising agent for the chemical stabilization of polluted soils. Copyright © 2015 Elsevier B.V. All rights reserved.

  10. Physical and chemical stability of palonosetron hydrochloride with dacarbazine and with methylprednisolone sodium succinate during simulated y-site administration.

    Science.gov (United States)

    Trissel, Lawrence A; Zhang, Yanping; Xu, Quanyun A

    2006-01-01

    The objective of this study was to evaluate the physical and chemical stability of mixtures of undiluted palonosetron hydrochloride 50 micrograms/mL with dacarbazine 4 mg/mL and with methylprednisolone sodium succinate 5 mg/mL in 5% dextrose injection during simulated Y-site administration. Triplicate test samples were prepared by admixing 7.5 mL of palonosetron hydrochloride with 7.5 mL of dacarbazine solution and, separately, methylprednisolone sodium succinate solution. Physical stability was assessed by using a multistep evaluation procedure that included both turbidimetric and particulate measurement as well as visual inspection. Chemical stability was assessed by using stability-indicating high-performance liquid chromatographic analytical techniques that determined drug concentrations. Evaluations were performed immediately after mixing and 1 and 4 hours after mixing. The palonosetron hydrochloride-dacarbazine samples were clear and colorless when viewed in normal fluorescent room light and when viewed with a Tyndall beam. Measured turbidities remained unchanged; particulate contents were low and exhibited little change. High-performance liquid chromatography analysis revealed that palonosetron hydrochloride and dacarbazine remained stable throughout the 4-hour test with no drug loss. Palonosetron hydrochloride is, therefore, physically compatible and chemically stable with dacarbazine during Y-site administration. Within 4 hours, the mixtures of palonosetron hydrochloride and methylprednisolone sodium succinate developed a microprecipitate that became a white precipitate visible to the unaided eye. The precipitate was analyzed and identified as methylprednisolone. Palonosetron hydrochloride is incompatible with methylprednisolone sodium succinate.

  11. Stabilization

    Directory of Open Access Journals (Sweden)

    Muhammad H. Al-Malack

    2016-07-01

    Full Text Available Fuel oil flyash (FFA produced in power and water desalination plants firing crude oils in the Kingdom of Saudi Arabia is being disposed in landfills, which increases the burden on the environment, therefore, FFA utilization must be encouraged. In the current research, the effect of adding FFA on the engineering properties of two indigenous soils, namely sand and marl, was investigated. FFA was added at concentrations of 5%, 10% and 15% to both soils with and without the addition of Portland cement. Mixtures of the stabilized soils were thoroughly evaluated using compaction, California Bearing Ratio (CBR, unconfined compressive strength (USC and durability tests. Results of these tests indicated that stabilized sand mixtures could not attain the ACI strength requirements. However, marl was found to satisfy the ACI strength requirement when only 5% of FFA was added together with 5% of cement. When the FFA was increased to 10% and 15%, the mixture’s strength was found to decrease to values below the ACI requirements. Results of the Toxicity Characteristics Leaching Procedure (TCLP, which was performed on samples that passed the ACI requirements, indicated that FFA must be cautiously used in soil stabilization.

  12. Application of a high-throughput relative chemical stability assay to screen therapeutic protein formulations by assessment of conformational stability and correlation to aggregation propensity.

    Science.gov (United States)

    Rizzo, Joseph M; Shi, Shuai; Li, Yunsong; Semple, Andrew; Esposito, Jessica J; Yu, Shenjiang; Richardson, Daisy; Antochshuk, Valentyn; Shameem, Mohammed

    2015-05-01

    In this study, an automated high-throughput relative chemical stability (RCS) assay was developed in which various therapeutic proteins were assessed to determine stability based on the resistance to denaturation post introduction to a chaotrope titration. Detection mechanisms of both intrinsic fluorescence and near UV circular dichroism (near-UV CD) are demonstrated. Assay robustness was investigated by comparing multiple independent assays and achieving r(2) values >0.95 for curve overlays. The complete reversibility of the assay was demonstrated by intrinsic fluorescence, near-UV CD, and biologic potency. To highlight the method utility, we compared the RCS assay with differential scanning calorimetry and dynamic scanning fluorimetry methodologies. Utilizing C1/2 values obtained from the RCS assay, formulation rank-ordering of 12 different mAb formulations was performed. The prediction of long-term stability on protein aggregation is obtained by demonstrating a good correlation with an r(2) of 0.83 between RCS and empirical aggregation propensity data. RCS promises to be an extremely useful tool to aid in candidate formulation development efforts based on the complete reversibility of the method to allow for multiple assessments without protein loss and the strong correlation between the C1/2 data obtained and accelerated stability under stressed conditions. © 2015 Wiley Periodicals, Inc. and the American Pharmacists Association.

  13. Assessing the physical-chemical properties and stability of dapivirine-loaded polymeric nanoparticles.

    Science.gov (United States)

    das Neves, José; Amiji, Mansoor; Bahia, Maria Fernanda; Sarmento, Bruno

    2013-11-18

    Nanocarriers may provide interesting delivery platforms for microbicide drugs and their characterization should be addressed early in development. Differently surface-engineered dapivirine-loaded, poly(epsilon-caprolactone) (PCL)-based nanoparticles (NPs) were obtained by nanoprecipitation using polyethylene oxide (PEO), sodium lauryl sulfate (SLS), or cetyltrimethylammonium bromide (CTAB) as surface modifiers. Physical-chemical properties of NP aqueous dispersions were evaluated upon storage at -20-40 °C for one year. NPs presented 170-200 nm in diameter, roundish-shape, low polydispersity index (≤0.18), and high drug association efficiency (≥97%) and loading (≥12.7%). NPs differed in zeta potential, depending on surface modifier (PEO: -27.9 mV; SLS: -54.7 mV; CTAB: +42.4 mV). No interactions among formulation components were detected by differential scanning calorimetry (DSC) and Fourier transform infrared spectroscopy (FTIR), except for SLS-PCL NPs. Colloidal properties of NPs were lost at -20 °C storage. Negatively charged NPs were stable up to one year at 5-40°C; as for CTAB-PCL NPs, particle aggregation was observed from 30 to 90 days of storage depending on temperature. Colloidal instability affected the in vitro drug release of CTAB-PCL NPs after 360 days. In any case, no degradation of dapivirine was apparent. Overall, PEO-PCL and SLS-PCL NPs presented suitable properties as nanocarriers for dapivirine. Conversely, CTAB-PCL NPs require additional strategies in order to increase stability. Copyright © 2013 Elsevier B.V. All rights reserved.

  14. Achieving synergy between chemical oxidation and stabilization in a contaminated soil.

    Science.gov (United States)

    Srivastava, Vipul J; Hudson, Jeffrey Michael; Cassidy, Daniel P

    2016-07-01

    Eight in situ solidification/stabilization (ISS) amendments were tested to promote in situ chemical oxidation (ISCO) with activated persulfate (PS) in a contaminated soil. A 3% (by weight) dose of all ISS amendments selected for this study completely activated a 1.5% dose of PS within 3 h by raising temperatures above 30 °C (heat activation) and/or increasing pH above 10.5 (alkaline activation). Heat is released by the reaction of CaO with water, and pH increases because this reaction produces Ca(OH)2. Heat activation is preferred because it generates 2 mol of oxidizing radicals per mole of PS, whereas alkaline activation releases only 1. The relative contribution of heat vs. alkaline activation increased with CaO content of the ISS amendment, which was reflected by enhanced contaminant oxidation with increasing CaO content, and was confirmed by comparing to controls promoting purely heat or alkaline (NaOH) activation. The test soil was contaminated with benzene, toluene, ethylbenzene, and xylenes (BTEX) and polycyclic aromatic hydrocarbons (PAH), particularly naphthalene (NAP). ISS-activated PS oxidized between 47% and 84% of the BTEX & NAP, and between 13% and 33% of the higher molecular weight PAH. ISS-activated PS reduced the leachability of BTEX & NAP by 76%-91% and of the 17 PAH by 83%-96%. Combined ISCO/ISS reduced contaminant leachability far than ISCO or ISS treatments alone, demonstrating the synergy that is possible with combined remedies. Copyright © 2016 Elsevier Ltd. All rights reserved.

  15. Gel layer formation on membranes in Membrane Bioreactors

    NARCIS (Netherlands)

    Van den Brink, P.F.H.

    2014-01-01

    The widespread application of membrane bioreactors (MBRs) for municipal wastewater treatment is hampered by membrane fouling. Fouling increases energy demand, reduces process performance and creates the need for more frequent (chemical) membrane cleaning or replacement. Membrane fouling in MBRs is

  16. Polyanionic pH-responsive polystyrene-b-poly(4-vinyl pyridine-N-oxide) isoporous membranes

    KAUST Repository

    Shevate, Rahul; Karunakaran, Madhavan; Kumar, Mahendra; Peinemann, Klaus-Viktor

    2015-01-01

    , but also the mechanical and chemical membrane stability was improved significantly. The modified membranes are insoluble in solvents like DMF, NMP and DMSO. Two kinds of PS-b-P4VP based isoporous membranes are available now with reverse flux response to p

  17. Application showcases for a small scale membrane contactor for fine chemical processes

    NARCIS (Netherlands)

    Roelands, C.P.M.; Ngene, I.S.

    2011-01-01

    The transition from batch to continuous processing in fine-chemicals industries offers many advantages; among these are a high volumetric productivity, improved control over reaction conditions resulting in a higher yield and selectivity, a small footprint and a safer process due to a smaller

  18. Polyarylenethioethersulfone Membranes for Fuel Cells (Postprint)

    Science.gov (United States)

    2010-01-01

    The Electrochemical SocietyProton exchange membrane fuel cells PEMFCs are an attrac- tive power source due to their energy efficiency and...standard in PEMFC technology.3,4 Nafion membranes have a polytetrafluoro- ethylene PTFE backbone, which provides thermal and chemical stability, and...diffusion layers to fabricate MEAs. Single-cell test (H- PEMFC ).— MEAs were positioned in a single-cell fixture with graphite blocks as current

  19. 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.

  20. Yeast Tok1p channel is a major contributor to membrane potential maintenance under chemical stress

    Czech Academy of Sciences Publication Activity Database

    Zahumenský, J.; Jančíková, I.; Drietomská, A.; Švenkrtová, Andrea; Hlaváček, Otakar; Hendrych, T.; Plášek, J.; Sigler, Karel; Gášková, D.

    2017-01-01

    Roč. 1859, č. 10 (2017), s. 1974-1985 ISSN 0005-2736 R&D Projects: GA ČR(CZ) GA15-08225S; GA MŠk LH13049; GA MŠk(CZ) ED1.1.00/02.0109 Institutional support: RVO:61388971 Keywords : Chemical stress * Depolarization * Fluorescent probe diS-C-3(3) Subject RIV: EE - Microbiology, Virology OBOR OECD: Microbiology Impact factor: 3.498, year: 2016

  1. Annulated Dialkoxybenzenes as Catholyte Materials for Non-aqueous Redox Flow Batteries: Achieving High Chemical Stability through Bicyclic Substitution

    International Nuclear Information System (INIS)

    Zhang, Jingjing; Yang, Zheng; Shkrob, Ilya A.; Assary, Rajeev S.

    2017-01-01

    1,4-Dimethoxybenzene derivatives are materials of choice for use as catholytes in nonaqueous redox flow batteries, as they exhibit high open-circuit potentials and excellent electrochemical reversibility. However, chemical stability of these materials in their oxidized form needs to be improved. Disubstitution in the arene ring is used to suppress parasitic reactions of their radical cations, but this does not fully prevent ring-addition reactions. By incorporating bicyclic substitutions and ether chains into the dialkoxybenzenes, a novel catholyte molecule, 9,10-bis(2-methoxyethoxy)-1,2,3,4,5,6,7,8-octahydro-1,4:5, 8-dimethanenoanthracene (BODMA), is obtained and exhibits greater solubility and superior chemical stability in the charged state. As a result, a hybrid flow cell containing BODMA is operated for 150 charge–discharge cycles with minimal loss of capacity.

  2. PHYSICAL AND CHEMICAL STABILITY ANALYSIS OF COSMETIC MULTI- PLE EMULSIONS LOADED WITH ASCORBYL PALMITATE AND SODIUM ASCORBYL PHOSPHATE SALTS.

    Science.gov (United States)

    Khan, Hira; Akhtar, Naveed; Ali, Atif; Khan, Haji M Shoaib; Sohail, Muhammad; Naeem, Muhammad; Nawaz, Zarqa

    2016-09-01

    Stability of hydrophilic and lipophilic vitamin C derivatives for quenching synergistic antioxidant activities and to treat oxidative related diseases is a major issue. This study was aimed to encapsulate hydrophilic and lipophilic vitamin C derivatives (ascorbyl palmitate and sodium ascorbyl phosphate) as functional ingredients in a newly formulated multiple emulsion of the W//W type to attain the synergistic antioxidant effects and the resultant system's long term physical and chemical stability. Several multiple emulsions using the same concentration of emulsifiers but different concentrations of ascorbyl palmitate and sodium ascorbyl phosphate were developed. Three finally selected multiple emulsions (ME₁, ME₂ and ME₃) were evaluated for physical stability in terms of rheology, microscopy, conductivity, pH, and organoleptic characteristics under different storage conditions for 3 months. Chemical stability was determined by HPLC on Sykam GmbH HPLC system (Germany), equipped with a variable UV detector. Results showed that at accelerated storage conditions all the three multiple emulsions had shear thinning behavior of varying shear stress with no influence of location of functional ingredients in a carrier system. Conductivity values increased and pH values remained within the skin pH range for 3 months. Microscopic analysis showed an increase in globule size with the passage of time, especially at higher temperatures while decreased at low temperatures. Centrifugation test did not cause phase separation till the 45th day, but little effects after 2 months. Chemical stability analysis by HPLC at the end of 3 months showed that ascorbyl palmitate and sodium ascorbyl phosphate were almost stable in all multiple emulsions with no influence of their location in a carrier system. Multiple emulsions were found a stable carrier for hydrophilic and lipophilic vitamin C derivatives to enhance their desired effects. Considering that many topical formulations

  3. Sequestration of maize crop straw C in different soils: role of oxyhydrates in chemical binding and stabilization as recalcitrance.

    Science.gov (United States)

    Song, Xiangyun; Li, Lianqing; Zheng, Jufeng; Pan, Genxing; Zhang, Xuhui; Zheng, Jinwei; Hussain, Qaiser; Han, Xiaojun; Yu, Xinyan

    2012-05-01

    While biophysical controls on the sequestration capacity of soils have been well addressed with physical protection, chemical binding and stabilization processes as well as microbial community changes, the role of chemical binding and stabilization has not yet well characterized for soil organic carbon (SOC) sequestration in rice paddies. In this study, a 6-month laboratory incubation with and without maize straw amendment (MSA) was conducted using topsoil samples from soils with different clay mineralogy and free oxy-hydrate contents collected across Southern China. The increase in SOC under MSA was found coincident with that in Fe- and Al-bound OC (Fe/Al-OC) after incubation for 30 d (R(2)=0.90, P=0.05), and with sodium dithionate-citrate-bicarbonate (DCB) extractable Fe after incubation for 180 d (R(2)=0.99, Psoils rich in DCB extractable Fe than those poor in DCB extractable Fe. The greater SOC sequestration in soils rich in DCB extractable Fe was further supported by the higher abundance of (13)C which was a natural signature of MSA. Moreover, a weak positive correlation of the increased SOC under MSA with the increased humin (R(2)=0.87, P=0.06) observed after incubation for 180 d may indicate a chemical stabilization of sequestered SOC as humin in the long run. These results improved our understanding of SOC sequestration in China's rice paddies that involves an initial chemical binding of amended C and a final stabilization as recalcitrant C of humin. Copyright © 2012 Elsevier Ltd. All rights reserved.

  4. Crosslinked Hexafluoropropylidene Polybenzimidazole Membranes with Chloromethyl Polysulfone for Fuel Cell Applications

    DEFF Research Database (Denmark)

    Yang, Jingshuai; Li, Qingfeng; Cleemann, Lars Nilausen

    2013-01-01

    Hexafluoropropylidene polybenzimidazole (F6PBI) was synthesized with excellent chemical stability and improved solubility. When doped with phosphoric acid, however, the F6PBI membranes showed plastic deformation at elevated temperatures. Further efforts were made to covalently crosslink F6PBI...... membranes with chloromethyl polysulfone as a polymeric crosslinker. Comparing with linear F6PBI and mPBI membranes, the polymer crosslinked F6PBI membranes exhibited little organo solubility, excellent stability towards the radical oxidation, high resistance to swelling in concentrated phosphoric acid...... with the linear F6PBI and mPBI membranes....

  5. Chemical stability of astaxanthin integrated into a food matrix: Effects of food processing and methods for preservation.

    Science.gov (United States)

    Martínez-Delgado, Alejandra Anahí; Khandual, Sanghamitra; Villanueva-Rodríguez, Socorro Josefina

    2017-06-15

    Astaxanthin is a carotenoid pigment found in numerous organisms ranging from bacteria to algae, yeasts, plants, crustaceans and fish such as salmon. Technological importance of this pigment emerged from various studies demonstrating that it is a powerful antioxidant, even with higher activity than alpha-tocopherol and other carotenoids. It has been included in various pharmaceutical products because of several beneficial properties. By its nature, astaxanthin is susceptible to degradation and can undergo chemical changes during food processing. Therefore, different studies have focused on improving the stability of the carotenoid under conditions such as high temperatures, pressures and mechanical force, among others. In this review, common processes involved in food processing and their effect on the stability of astaxanthin, integrated into a food matrix are discussed. Moreover, preservation techniques such as microencapsulation, inclusion in emulsions, suspensions, liposomes, etc., that are being employed to maintain stability of the product are also reviewed. Copyright © 2016 Elsevier Ltd. All rights reserved.

  6. Enhancement in Proton Conductivity and Thermal Stability in Nafion Membranes Induced by Incorporation of Sulfonated Carbon Nanotubes.

    Science.gov (United States)

    Yin, Chongshan; Li, Jingjing; Zhou, Yawei; Zhang, Haining; Fang, Pengfei; He, Chunqing

    2018-04-25

    Proton exchange membrane fuel cell (PEMFC) is one of the most promising green power sources, in which perfluorinated sulfonic acid ionomer-based membranes (e.g., Nafion) are widely used. However, the widespread application of PEMFCs is greatly limited by the sharp degradation in electrochemical properties of the proton exchange membranes under high temperature and low humidity conditions. In this work, the high-performance sulfonated carbon nanotubes/Nafion composite membranes (Su-CNTs/Nafion) for the PEMFCs were prepared and the mechanism of the microstructures on the macroscopic properties of membranes was intensively studied. Microstructure evolution in Nafion membranes during water uptake was investigated by positron annihilation lifetime spectroscopy, and results strongly showed that the Su-CNTs or CNTs in Nafion composite membranes significantly reinforced Nafion matrices, which influenced the development of ionic-water clusters in them. Proton conductivities in Su-CNTs/Nafion composite membranes were remarkably enhanced due to the mass formation of proton-conducting pathways (water channels) along the Su-CNTs. In particular, these pathways along Su-CNTs in Su-CNTs/Nafion membranes interconnected the isolated ionic-water clusters at low humidity and resulted in less tortuosity of the water channel network for proton transportation at high humidity. At a high temperature of 135 °C, Su-CNTs/Nafion membranes maintained high proton conductivity because the reinforcement of Su-CNTs on Nafion matrices reduced the evaporation of water molecules from membranes as well as the hydrophilic Su-CNTs were helpful for binding water molecules.

  7. Chemical Stability of Cd(II and Cu(II Ionic Imprinted Amino-Silica Hybrid Material in Solution Media

    Directory of Open Access Journals (Sweden)

    Buhani, Narsito, Nuryono, Eko Sri Kunarti

    2015-12-01

    Full Text Available Chemical stability of Cd(II and Cu(II ionic imprinted hybrid material of (i-Cd-HAS and i-Cu-HAS derived from silica modification with active compound (3-aminopropyl-trimethoxysilane (3-APTMS has been studied in solution media. Stability test was performed with HNO3 0.1 M (pH 1.35 to investigate material stability at low pH condition, CH3COONa 0.1 M (pH 5.22 for adsorption process optimum pH condition, and in the water (pH 9.34 for base condition. Material characteristics were carried out with infrared spectrophotometer (IR and atomic absorption spectrophotometer (AAS. At interaction time of 4 days in acid and neutral condition, i-Cd-HAS is more stable than i-Cu-HAS with % Si left in material 95.89 % (acid media, 43.82 % (close to neutral, and 9.39 % (base media.Keywords: chemical stability, amino-silica hybrid, ionic imprinting technique

  8. Chemical Stability of Cd(II and Cu(II Ionic Imprinted Amino-Silica Hybrid Material in Solution Media

    Directory of Open Access Journals (Sweden)

    Buhani Buhani

    2012-02-01

    Full Text Available Chemical stability of Cd(II and Cu(II ionic imprinted amino-silica (HAS material of (i-Cd-HAS and i-Cu-HAS derived from silica modification with active compound (3-aminopropyl-trimethoxysilane (3-APTMS has been studied in solution media.  Stability test was performed with HNO3 0.1 M (pH 1.35 to investigate material stability at low pH condition, acetat buffer at pH 5.22 for adsorption process optimum pH condition, and in the water (pH 9.34 for base condition.  Material characteristics were carried out with infrared spectrophotometer (IR and atomic absorption spectrophotometer (AAS.  At interaction time of 4 days in acid and neutral condition, i-Cd-HAS is more stable than i-Cu-HAS with % Si left in material 95.89 % (acid media, 43.82 % (close to neutral, and 9.39 % (base media.Keywords: chemical stability, amino-silica hybrid, ionic imprinting technique.

  9. Effect of stabilizers on the physico-chemical and sensory attributes ...

    African Journals Online (AJOL)

    Stabilized thermized yoghurt was produced by the addition of gelatin, carboxyl methyl cellulose (CMC) and corn starch, into yoghurt mix as stabilizers, each at 0, 0.5, 0.75 and 1.0% concentrations. The yoghurt samples produced after pasteurization of the mix, cooling, inoculation of starter culture and incubation for about 16 ...

  10. Stability issues of conjugated polymer / fullerene solar cells from a chemical viewpoint

    NARCIS (Netherlands)

    Hummelen, J.C.; Knol, J.; Sánchez, L.

    2001-01-01

    The efficiency of energy conversion and the stability or lifetime of ‘plastic’ photovoltaic cells, based on conjugated polymer/ fullerene blends, are the two main issues to be improved for this type of devices. The stability of these PV cells depends potentially on a large number of factors. A brief

  11. Treatment of tannery wastewater for reuse by physico-chemical processes and a membrane bioreactor

    Directory of Open Access Journals (Sweden)

    J. Fettig

    2017-12-01

    Full Text Available Treatment of wastewater from a tannery in Greater Ho Chi Minh City (Vietnam was investigated on a pilot scale. After pre-treatment by the tannery that included batch-coagulation and sedimentation, the wastewater was treated by dissolved air flotation, a membrane bioreactor (MBR and granular activated carbon (GAC for polishing the MBR effluent. The average removal efficiency for organic substances in the MBR was 81% while total nitrogen could only be removed by 36%. The performance of the GAC column could be successfully predicted using adsorption parameters determined in laboratory experiments. A larger proportion of the organics in the MBR effluent was only weakly adsorbable, therefore the usable carbon capacity was limited as confirmed by the modelling approach. The results were used to outline the size of a technical plant with a volumetric loading rate of 3 kg COD/(m3*d for the MBR and a specific carbon demand of about 1.8 kg/m3.

  12. Matrimid®/polysulfone blend mixed matrix membranes containing ZIF-8 nanoparticles for high pressure stability in natural gas separation

    NARCIS (Netherlands)

    Shahid, S.; Nijmeijer, K.

    2017-01-01

    Plasticization is of important concern in high pressure natural gas separation. Majority of the pure polymers and MOF-MMM systems suffer from plasticization at low pressures. Combination of polymer blending and MMM approach could lead to plasticization resistant membranes with improved membrane

  13. Bacterial Reaction Centers Purified with Styrene Maleic Acid Copolymer Retain Native Membrane Functional Properties and Display Enhanced Stability**

    Science.gov (United States)

    Swainsbury, David J K; Scheidelaar, Stefan; van Grondelle, Rienk; Killian, J Antoinette; Jones, Michael R

    2014-01-01

    Integral membrane proteins often present daunting challenges for biophysical characterization, a fundamental issue being how to select a surfactant that will optimally preserve the individual structure and functional properties of a given membrane protein. Bacterial reaction centers offer a rare opportunity to compare the properties of an integral membrane protein in different artificial lipid/surfactant environments with those in the native bilayer. Here, we demonstrate that reaction centers purified using a styrene maleic acid copolymer remain associated with a complement of native lipids and do not display the modified functional properties that typically result from detergent solubilization. Direct comparisons show that reaction centers are more stable in this copolymer/lipid environment than in a detergent micelle or even in the native membrane, suggesting a promising new route to exploitation of such photovoltaic integral membrane proteins in device applications. PMID:25212490

  14. Properties of Polyethylene Naphthalate Track Membranes

    CERN Document Server

    Akimenko, S N; Orelovich, O L; Maekawa, J; Ioshida, M; Apel, P Yu

    2002-01-01

    Basic characteristics of track membranes made of polyethylene naphthalate (which is a polyester synthesized from dimethyl naphthalate and ethylene glycol) are studied and presented. Polyethylene naphthalate possesses some properties (mechanical strength, thermal and chemical stability), which make this polymer a promising material for the production of track membranes. Water flow rate and air flow rate characteristics, burst strength, wettability, and amount of extractables are determined. Surface structure and pore structure are examined using scanning electron microscopy. It is found that the pores in the membranes are cylindrical in shape. The measured water and air flow rates follow known theoretical relations for the transport in narrow capillaries. The burst strength of polyethylene naphthalate membranes is found to be similar to that of polyethylene terephthalate track membranes. Polyethylene naphthalate track membranes can be categorized as moderately hydrophilic. Being treated with boiling water, pol...

  15. Storage stability of margarines produced from enzymatically interesterified fats compared to those prepared by conventional methods - Chemical properties

    DEFF Research Database (Denmark)

    Zhang, Hong; Jacobsen, Charlotte; Pedersen, Lars Saaby

    2006-01-01

    margarines in a pilot plant. Storage stability studies were carried out at storage temperatures of 5 and 25øC for 12wk. Margarines from the enzymatically interesterified fats were compared to the margarines produced by the conventional methods (chemical interesterification and physical blending......In this study, four margarine hardstocks were produced, two from enzymatically interesterified fats at 80 and 100% conversion, one from chemically randomized fat and one from physically mixed fat. These four hardstocks, blended with 50% sunflower oil, were mainly used for the production of table...... interesterified fat had higher PV in weeks4, 8 and10 than the margarines produced from the enzymatically interesterified fats and the physically blended fat. These differences were not caused by different contents of tocopherols in the hardstocks. The differences between the processes for chemical and enzymatic...

  16. Gravity-driven membrane filtration as pretreatment for seawater reverse osmosis: linking biofouling layer morphology with flux stabilization.

    Science.gov (United States)

    Akhondi, Ebrahim; Wu, Bing; Sun, Shuyang; Marxer, Brigit; Lim, Weikang; Gu, Jun; Liu, Linbo; Burkhardt, Michael; McDougald, Diane; Pronk, Wouter; Fane, Anthony G

    2015-03-01

    In this study gravity-driven membrane (GDM) ultrafiltration is investigated for the pretreatment of seawater before reverse osmosis (RO). The impacts of temperature (21 ± 1 and 29 ± 1 °C) and hydrostatic pressure (40 and 100 mbar) on dynamic flux development and biofouling layer structure were studied. The data suggested pore constriction fouling was predominant at the early stage of filtration, during which the hydrostatic pressure and temperature had negligible effects on permeate flux. With extended filtration time, cake layer fouling played a major role, during which higher hydrostatic pressure and temperature improved permeate flux. The permeate flux stabilized in a range of 3.6 L/m(2) h (21 ± 1 °C, 40 mbar) to 7.3 L/m(2) h (29 ± 1 °C, 100 mbar) after slight fluctuations and remained constant for the duration of the experiments (almost 3 months). An increase in biofouling layer thickness and a variable biofouling layer structure were observed over time by optical coherence tomography and confocal laser scanning microscopy. The presence of eukaryotic organisms in the biofouling layer was observed by light microscopy and the microbial community structure of the biofouling layer was analyzed by sequences of 16S rRNA genes. The magnitude of permeate flux was associated with the combined effect of the biofouling layer thickness and structure. Changes in the biofouling layer structure were attributed to (1) the movement and predation behaviour of the eukaryotic organisms which increased the heterogeneous nature of the biofouling layer; (2) the bacterial debris generated by eukaryotic predation activity which reduced porosity; (3) significant shifts of the dominant bacterial species over time that may have influenced the biofouling layer structure. As expected, most of the particles and colloids in the feed seawater were removed by the GDM process, which led to a lower RO fouling potential. However, the dissolved organic carbon in the

  17. Transport Properties, Mechanical Behavior, Thermal and Chemical Resistance of Asymmetric Flat Sheet Membrane Prepared from PSf/PVDF Blended Membrane on Gauze Supporting Layer

    Directory of Open Access Journals (Sweden)

    Nita Kusumawati

    2018-05-01

    Full Text Available Asymmetric polysulfone (PSf membrane is prepared using phase inversion method and blending with polyvinylidene fluoride (PVDF on the gauze solid support. Casting solution composition optimization has been done to get PSf/PVDF membrane with best characteristics and permeability. The result shows that blending on PSf with PVDF polymer using phase inversion method has been very helpful in creating an asymmetric porous membrane. Increased level of PVDF in casting solution has increased the formation of asymmetry structure and corresponding flux membrane. The result from thermal test using Differential Scanning Calorimetry (DSC-Thermal Gravimetric Analysis (TGA shows the resistance of the membrane to temperature 460 °C. Membrane resistance against acid looks from undetectable changes on infrared spectra after immersion process in H2SO4 6–98 v/v%. While membrane color changes from white to brownish and black is detected after the immersion process in sodium hydroxide (NaOH 0.15–80 w/v%.

  18. Influence of particle size and preparation methods on the physical and chemical stability of amorphous simvastatin

    DEFF Research Database (Denmark)

    Zhang, Fang; Aaltonen, Jaakko; Tian, Fang

    2009-01-01

    This study investigated the factors influencing the stability of amorphous simvastatin. Quench-cooled amorphous simvastatin in two particle size ranges, 150-180 microm (QC-big) and ... compared to the crystalline form. The rank of solubility was found to be QC-big=QC-small>CM>crystalline. For the physical stability, the highest crystallization rate was observed for CM, and the slowest rate was detected for QC-big, with an intermediate rate occurring for QC-small. QC exhibited lower...

  19. Chemical and physical aspects of the stability of mica on heating

    International Nuclear Information System (INIS)

    Muromtsev, V.A.; Arkhangel'skii, S.V.; Egorov, S.V.

    1989-01-01

    An attempt was made in this study to comparatively determine the degree of hydration and thermal stability of micas and to analyze the possible causes of differences in interpreting the results on establishment of the degree of hydration on the example of phlogopites from the Kovdor and Aldan deposits by methods of flame photometry, γ-radiometric determination of K 2 O, thermal stability, and gravimetric methods of analysis of the moisture content and weight loss in calcination

  20. Studies on the stability of 3H-dopamine in neostriatal membrane preparations: effects of ascorbic acid

    International Nuclear Information System (INIS)

    Heikkila, R.E.; Cabbat, F.S.

    1983-01-01

    The rate of 3 H-dopamine decomposition was determined in buffers and in neostriatal membrane preparations that are commonly used in binding experiments. The rate of decomposition of 3 H-dopamine was inhibited considerably by the membrane preparation and by ascorbic acid. Under conditions in which the binding of 3 H-dopamine is routinely measured in neostriatal membrane preparations, there was almost no 3 H-dopamine decomposition. The data would seem to suggest that the routine addition of very high concentrations of antioxidants is unnecessary when 3 H-dopamine binding is being determined

  1. Stabilization of the H,K-ATPase M5M6 membrane hairpin by K+ ions. Mechanistic significance for p2-type atpases.

    Science.gov (United States)

    Gatto, C; Lutsenko, S; Shin, J M; Sachs, G; Kaplan, J H

    1999-05-14

    The integral membrane protein, the gastric H,K-ATPase, is an alpha-beta heterodimer, with 10 putative transmembrane segments in the alpha-subunit and one such segment in the beta-subunit. All transmembrane segments remain within the membrane domain following trypsinization of the intact gastric H,K-ATPase in the presence of K+ ions, identified as M1M2, M3M4, M5M6, and M7, M8, M9, and M10. Removal of K+ ions from this digested preparation results in the selective loss of the M5M6 hairpin from the membrane. The release of the M5M6 fragment is directed to the extracellular phase as evidenced by the accumulation of the released M5M6 hairpin inside the sealed inside out vesicles. The stabilization of the M5M6 hairpin in the membrane phase by the transported cation as well as loss to the aqueous phase in the absence of the transported cation has been previously observed for another P2-type ATPase, the Na, K-ATPase (Lutsenko, S., Anderko, R., and Kaplan, J. H. (1995) Proc. Natl. Acad. Sci. U. S. A. 92, 7936-7940). Thus, the effects of the counter-transported cation on retention of the M5M6 segment in the membrane as compared with the other membrane pairs may be a general feature of P2-ATPase ion pumps, reflecting a flexibility of this region that relates to the mechanism of transport.

  2. Obtention of selective membranes for water and hydrophobic liquids by plasma enhanced chemical vapor deposition on porous substrates

    International Nuclear Information System (INIS)

    Bankovic, P.; Demarquette, N.R.; Silva, M.L.P. da

    2004-01-01

    In this work, the possibility of obtaining selective membranes for water and hydrophobic liquids by plasma enhanced chemical vapor deposition (PECVD) of hexamethyldisilazane (HMDS) or double layers of HMDS and n-hexane on porous substrates using a capacitive plasma reactor was investigated. The porous substrates used were paper filter, diatomite and polyester textiles. The films were characterized by X-ray photoelectron spectroscopy (XPS), attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR) and contact angle measurements. The membranes obtained were characterized by the Cobb test. Their efficiency to separate hydrocarbon compounds from water was evaluated through filtration experiments and Karl-Fischer titration tests. The reagents used in the filtration experiments were: chloroform, n-hexane, n-heptane, ethyl ether, benzene and diesel. XPS analysis showed that Si, N, C and O were present at the surface of the film. C peak was dominant in the double layer film spectra. C-H n , CH 2 , Si-H, Si-CH 3 , N-H, Si-CH 2 -Si, Si-N-Si and Si-C bonds were identified in both types of the films by ATR-FTIR. The relative intensities of the corresponding peaks in the two spectra were different. The XPS and FTIR results indicated that C was most likely present in a CH n form at the surface of double layer film. The average contact angles formed by drops of water on the film surface ranged from 135 deg. to 155 deg. . Water adsorption measured by Cobb test decreased from average values ranging from 300 to 9000 g m -2 (for nonmodified surfaces) to values ranging from 0 to 20 g m -2 (for treated surfaces). The Karl-Fischer titration indicated that between 90 and 1000 ppm (depending on the reagent used) of water remained in the hydrocarbon compound after filtration

  3. 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.

  4. In-line formation of chemically cross-linked P84® co-polyimide hollow fibre membranes for H2/CO2 separation

    KAUST Repository

    Choi, Seung Hak

    2010-12-13

    In this study, chemically cross-linked asymmetric P84® co-polyimide hollow fibre membranes with enhanced separation performance were fabricated, using a dry-wet spinning process with an innovative in-line cross-linking step. The chemical modification was conducted by controlled immersion of the coagulated fibre in an aqueous 1,5-diamino-2-methylpentane (DAMP) cross-linker solution before the take-up. The effect of the cross-linker concentration on the thermal, mechanical, chemical and gas transport properties of the membranes was investigated. FT-IR/ATR analysis was used to identify the chemical changes in the polymer, while DSC analysis confirmed the changes in the Tg and the specific heat of the polymer upon cross-linking. Chemical cross-linking with a 10 wt.% aqueous DAMP solution strongly enhanced the H2/CO2 ideal selectivity from 5.3 to 16.1, while the H2 permeance of the membranes decreased from 7.06 × 10−3 to 1.01 × 10−3 m3(STP) m−2 h−1 bar−1 for a feed pressure of 1 bar at 25 °C. The increase of selectivity with decreasing permeance is somewhat higher than the slope in the Robeson upper bound, evidencing the positive effect of the cross-linking on the separation performance of the fibres. Simultaneously, the cross-linking leads to improved mechanical resistance of the membranes, which could be further enhanced by an additional thermal treatment. The produced membranes are therefore more suitable for use under harsh conditions and have a better overall performance than the uncross-linked ones.

  5. Ionic Conductivity and Cycling Stability Improvement of PVDF/Nano-Clay Using PVP as Polymer Electrolyte Membranes for LiFePO4 Batteries

    Directory of Open Access Journals (Sweden)

    Endah R. Dyartanti

    2018-07-01

    Full Text Available In this paper, we present the characteristics and performance of polymer electrolyte membranes (PEMs based on poly(vinylidene fluoride (PVDF. The membranes were prepared via a phase-inversion method (non-solvent-induced phase separation (NIPS. As separators for lithium battery systems, additive modified montmorillonite (MMT nano-clay served as a filler and poly(vinylpyrrolidone (PVP was used as a pore-forming agent. The membranes modified with an additive (8 wt % nano-clay and 7 wt % PVP showed an increased porosity (87% and an uptake of a large amount of electrolyte (801.69%, which generated a high level of ionic conductivity (5.61 mS cm−1 at room temperature. A graphite/PEMs/LiFePO4 coin cell CR2032 showed excellent stability in cycling performance (average discharge capacity 127 mA h g−1. Based on these results, PEMs are promising materials to be used in Polymer Electrolyte Membranes in lithium-ion batteries.

  6. A study on the chemical stability and electrode performance of modified NiO cathodes for molten carbonate fuel cells

    International Nuclear Information System (INIS)

    Kim, Seung-Goo; Yoon, Sung Pil; Han, Jonghee; Nam, Suk Woo; Lim, Tae Hoon; Oh, In-Hwan; Hong, Seong-Ahn

    2004-01-01

    The chemical stabilities of modified NiO cathodes doped with 1.5 mol% CoO and 1.5 mol% LiCoO 2 fabricated by a conventional tape casting method were evaluated through the real MCFC single cell operation. The heat-treated samples before oxidation had proper porosities and microstructures for a MCFC cathode. At 150 mA cm -2 in current density, the MCFC single cell using a CoO-doped NiO cathode showed stable cell voltages in the range of 0.833-0.843 V for 1000 h. In contrast, the cell using a LiCoO 2 -doped NiO cathode with a maximum of 0.836 V at 500 h degraded to 0.826 V at 1000 h due to a wet seal breakdown at the cathode side. The amounts of nickel precipitated in the electrolytes of the cells using modified NiO cathodes doped with CoO and LiCoO 2 after the operation for 1000 h were 1.2 and 1.4 wt.%, respectively, which were about 60% lower than that of the standard cells using pure NiO cathodes. The enhanced chemical stability of modified NiO cathodes seems to be attributed to the fact that the presence of cobalt increases the lithium content in the cathodes by converting Ni 2+ to Ni 3+ , resulting in stabilizing the layered crystal structure

  7. Organic-inorganic hybrid membranes in separation processes: a 10-year review

    Directory of Open Access Journals (Sweden)

    V. C. Souza

    2013-12-01

    Full Text Available In relation to some inorganic membranes, polymeric membranes have relatively low separation performance. However, the processing flexibility and low cost of polymers still make them highly attractive for many industrial separation applications. Polymer-inorganic hybrid membranes constitute an emerging research field and have been recently developed to improve the separation properties of polymer membranes because they possess properties of both organic and inorganic membranes such as good hydrophilicity, selectivity, permeability, mechanical strength, and thermal and chemical stability. The structures and processing of polymer-inorganic nanocomposite hybrid membranes, as well as their use in the fields of ultrafiltration, nanofiltration, pervaporation, gas separation and separation mechanism are reviewed.

  8. EFFECT OF STABILIZERS ON THE CHEMICAL AND PHOTODEGRADATION OF ASCORBIC ACID IN AQUEOUS SOLUTION

    Directory of Open Access Journals (Sweden)

    Iqbal Ahmad

    2016-06-01

    Full Text Available Ascorbic acid (vitamin C is susceptible to light and air and forms various degradation products. A number of stabilizers have been used to study their effect on the degradation of ascorbic acid (AH2 in dark and light at pH 4.0 and 6.0 alone and in combination with citric and tartaric acids. The assay of AH2 in degraded solutions was performed by a specific UV spectrometric method. The degradation product of AH2 at pH 4.0 and 6.0 was identified as dehydroascorbic acid. The degradation of AH2 has been found to follow first-order kinetics. The apparent first-order rate constants, t90 and percent inhibition in rate in the presence of stabilizers and the second-order rate constants for the interaction of stabilizers with AH2 have been determined. The highest stabilizing effect on AH2 was found by sodium metabisulfite, followed by sodium sulfite, sodium bisulfate, sodium thiosulfate and thiourea. The pH of the solutions has also been found to influence the degradation of AH2 as the rates are higher at pH 6.0 compared to those of pH 4.0, probably due to the ionization of AH2. A synergistic effect has been observed when citric or tartaric acid was added to the solutions containing stabilizers where citric acid showed comparatively better effect.

  9. Progress in surface and membrane science

    CERN Document Server

    Cadenhead, D A

    1979-01-01

    Progress in Surface and Membrane Science, Volume 12 covers the advances in the study of surface and membrane science. The book discusses the topographical differentiation of the cell surface; the NMR studies of model biological membrane system; and an irreversible thermodynamic approach to energy coupling in mitochondria and chloroplasts. The text also describes water at surfaces; the nature of microemulsions; and the energy principle in the stability of interfaces. Biochemists, physicists, chemical engineers, and people involved in surface and coatings research will find the book invaluable.

  10. Properties, degradation and high temperature fuel cell test of different types of PBI and PBI blend membranes

    DEFF Research Database (Denmark)

    Li, Qingfeng; Rudbeck, Hans Christian; Chromik, Andreas

    2010-01-01

    Polybenzimidazoles (PBIs) with synthetically modified structures and their blends with a partially fluorinated sulfonated aromatic polyether have been prepared and characterized for high temperature proton exchange membrane fuel cells. Significant improvement in the polymer chemical stability...

  11. Exploring the potential of commercial polyethylene membranes for desalination by membrane distillation

    KAUST Repository

    Zuo, Jian; Bonyadi, Sina; Chung, Neal Tai-Shung

    2015-01-01

    The potential of utilizing polyethylene (PE) membranes in membrane distillation (MD) for sea water desalination has been explored in this study. The advantages of using PE membranes are (1) their intrinsic hydrophobicity with low surface energy of 28-33×10N/m, (2) good chemical stability and low thermal conductivity and (3) their commercial availability that may expedite the MD commercialization process. Several commercial PE membranes with different physicochemical properties are employed to study the capability and feasibility of PE membrane application in an MD process. The effect of membrane pore size, porosity, thickness and wetting resistance on MD performance and energy efficiency have been investigated. The PE membranes demonstrate impressive separation performance with permeation fluxes reaching 123.0L/mh for a 3.5wt% sodium chloride (NaCl) feed solution at 80°C. This superior performance surpasses most of the prior commercial and lab-made flat sheet and hollow fiber membranes. A long term MD testing of 100h is also performed to evaluate the durability of PE membranes, and a relatively stable performance is observed during the entire experiment. This long term stability signifies the suitability of PE membranes for MD applications.

  12. Exploring the potential of commercial polyethylene membranes for desalination by membrane distillation

    KAUST Repository

    Zuo, Jian

    2015-09-26

    The potential of utilizing polyethylene (PE) membranes in membrane distillation (MD) for sea water desalination has been explored in this study. The advantages of using PE membranes are (1) their intrinsic hydrophobicity with low surface energy of 28-33×10N/m, (2) good chemical stability and low thermal conductivity and (3) their commercial availability that may expedite the MD commercialization process. Several commercial PE membranes with different physicochemical properties are employed to study the capability and feasibility of PE membrane application in an MD process. The effect of membrane pore size, porosity, thickness and wetting resistance on MD performance and energy efficiency have been investigated. The PE membranes demonstrate impressive separation performance with permeation fluxes reaching 123.0L/mh for a 3.5wt% sodium chloride (NaCl) feed solution at 80°C. This superior performance surpasses most of the prior commercial and lab-made flat sheet and hollow fiber membranes. A long term MD testing of 100h is also performed to evaluate the durability of PE membranes, and a relatively stable performance is observed during the entire experiment. This long term stability signifies the suitability of PE membranes for MD applications.

  13. 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.

  14. Chemical stabilization of metals and arsenic in contaminated soils using oxides – A review

    International Nuclear Information System (INIS)

    Komárek, Michael; Vaněk, Aleš; Ettler, Vojtěch

    2013-01-01

    Oxides and their precursors have been extensively studied, either singly or in combination with other amendments promoting sorption, for in situ stabilization of metals and As in contaminated soils. This remediation option aims at reducing the available fraction of metal(loid)s, notably in the root zone, and thus lowering the risks associated with their leaching, ecotoxicity, plant uptake and human exposure. This review summarizes literature data on mechanisms involved in the immobilization process and presents results from laboratory and field experiments, including the subsequent influence on higher plants and aided phytostabilization. Despite the partial successes in the field, recent knowledge highlights the importance of long-term and large-scale field studies evaluating the stability of the oxide-based amendments in the treated soils and their efficiency in the long-term. - In situ stabilization of metals and As in contaminated soils using oxides combined with phytostabilization is a potential alternative to conventional remediation techniques.

  15. There Is Still Room for Improvement: Presentation of a Neutral Borosilicate Glass with Improved Chemical Stability for Parenteral Packaging.

    Science.gov (United States)

    Boltres, Bettine; Tratzky, Stephan; Kass, Christof; Eichholz, Rainer; Naß, Peter

    2016-01-01

    For pharmaceutical parenteral packaging the glass compositions have always been either Type I borosilicate or Type III soda-lime glass. As both the compositions and certain chemical and physical properties are mandated by international standards, there has not been room for any changes. However, by applying only minor adjustments, a borosilicate glass was developed that showed improved chemical stability. The chemical composition is still in the range of currently used borosilicate glasses, which makes it a Type I glass according to all current pharmacopeia. A study was performed on glass vials comparing the new glass with the standard FIOLAX(®) and two other publicly available glasses. In an extraction study with water at 121 °C the new glass showed the highest chemical stability with the lowest amount of extractables. In an accelerated ageing study, which was done with water, phosphate, and carbonate buffer at 40 °C for 12 months, the new glass also proved to have the lowest amount of leachables. In this article the new glass and the results from the studies are presented, showing the reader how much of an effect can be attained with only minor adjustments if the scientific fundamentals are clear. The pharmaceutical market has been quite constant and risk-oriented due to the high impact on the safety of the patient. As any change necessitates a complicated change process, this has, in consequence, lead the industry to resist changing the parenteral primary packaging material for decades. The main glasses have either been Type I borosilicate or Type III soda-lime glass. On the other hand, a combination of improved inspection systems and the development of more sensitive biologically based drugs has elevated the standards for parental packaging materials. For example, the measurement of extractables and leachables from the packaging material steadily came into focus. In this article, a new glass is presented that still belongs to the group of Type I borosilicate

  16. Stability of integral membrane proteins under high hydrostatic pressure: the LH2 and LH3 antenna pigment-protein complexes from photosynthetic bacteria.

    Science.gov (United States)

    Kangur, Liina; Timpmann, Kõu; Freiberg, Arvi

    2008-07-03

    The bacteriochlorophyll a-containing LH2 and LH3 antenna complexes are the integral membrane proteins that catalyze the photosynthetic process in purple photosynthetic bacteria. The LH2 complex from Rhodobacter sphaeroides shows characteristic strong absorbance at 800 and 850 nm due to the pigment molecules confined in two separate areas of the protein. In the LH3 complex from Rhodopesudomonas acidophila the corresponding bands peak at 800 and 820 nm. Using the bacteriochlorophyll a cofactors as intrinsic probes to monitor local changes in the protein structure, we investigate spectral responses of the antenna complexes to very high hydrostatic pressures up to 2.5 GPa when embedded into natural membrane environment or extracted with detergent. We first demonstrate that high pressure does induce significant alterations to the tertiary structure of the proteins not only in proximity of the 800 nm-absorbing bacteriochlorophyll a molecules known previously (Gall, A.; et al. Biochemistry 2003, 42, 13019) but also of the 850 nm- and 820 nm-absorbing molecules, including breakage of the hydrogen bond they are involved in. The membrane-protected complexes appear more resilient to damaging effects of the compression compared with the complexes extracted into mixed detergent-buffer environment. Increased resistance of the isolated complexes is observed at high protein concentration resulting aggregation as well as when cosolvent (glycerol) is added into the solution. These stability variations correlate with ability of penetration of the surrounding polar solvent (water) into the hydrophobic protein interiors, being thus the principal reason of the pressure-induced denaturation of the proteins. Considerable variability of elastic properties of the isolated complexes was also observed, tentatively assigned to heterogeneous protein packing in detergent micelles. While a number of the isolated complexes release most of their bacteriochlorophyll a content under high pressure

  17. Development of a human corneal epithelium model utilizing a collagen vitrigel membrane and the changes of its barrier function induced by exposing eye irritant chemicals.

    Science.gov (United States)

    Takezawa, Toshiaki; Nishikawa, Kazunori; Wang, Pi-Chao

    2011-09-01

    The brief TEER (trans-epithelial electrical resistance) assay after exposing chemicals to corneal epithelium in vivo is known as a suitable method for evaluating corneal irritancy and permeability quantitatively and continuously. A collagen vitrigel membrane we previously developed is a thin (about 20 μm thick) and transparent membrane composed of high density collagen fibrils equivalent to connective tissues in vivo, e.g. corneal Bowman's membrane. To develop such a TEER assay system in vitro utilizing a human corneal epithelial model, HCE-T cells (a human corneal epithelial cell line) were cultured on the collagen vitrigel membrane substratum prepared in a Millicell chamber suitable for TEER measurement. Human corneal epithelium model possessing 5-6 cell layers sufficient for TEER assay was successfully reconstructed on the substratum in the Millicell chamber by culturing the cells in monolayer for 2 days and subsequently in air-liquid interface for 7 days. The exposure of chemicals to the model induced the time-dependent relative changes of TEER in response to the characteristic of each chemical within a few minutes. These results suggest that the TEER assay using the human corneal epithelial model is very useful for an ocular irritancy evaluation as an alternative to the Draize eye irritation test. Copyright © 2011 Elsevier Ltd. All rights reserved.

  18. Stabilization of collagen nanofibers with l-lysine improves the ability of carbodiimide cross-linked amniotic membranes to preserve limbal epithelial progenitor cells

    Directory of Open Access Journals (Sweden)

    Lai JY

    2014-11-01

    Full Text Available Jui-Yang Lai,1–3 Pei-Ran Wang,1 Li-Jyuan Luo,1 Si-Tan Chen1 1Institute of Biochemical and Biomedical Engineering, 2Biomedical Engineering Research Center, 3Molecular Medicine Research Center, Chang Gung University, Taoyuan, Taiwan, Republic of ChinaAbstract: To overcome the drawbacks associated with limited cross-linking efficiency of carbodiimide modified amniotic membrane, this study investigated the use of L-lysine as an additional amino acid bridge to enhance the stability of a nanofibrous tissue matrix for a limbal epithelial cell culture platform. Results of ninhydrin assays and zeta potential measurements showed that the amount of positively charged amino acid residues incorporated into the tissue collagen chains is highly correlated with the L-lysine -pretreated concentration. The cross-linked structure and hydrophilicity of amniotic membrane scaffolding materials affected by the lysine molecular bridging effects were determined. With an increase in the L-lysine-pretreated concentration from 1 to 30 mM, the cross-linking density was significantly increased and water content was markedly decreased. The variations in resistance to thermal denaturation and enzymatic degradation were in accordance with the number of cross-links per unit mass of amniotic membrane, indicating L-lysine-modulated stabilization of collagen molecules. It was also noteworthy that the carbodiimide cross-linked tissue samples prepared using a relatively high L-lysine-pretreated concentration (ie, 30 mM appeared to have decreased light transmittance and biocompatibility, probably due to the influence of a large nanofiber size and a high charge density. The rise in stemness gene and protein expression levels was dependent on improved cross-link formation, suggesting the crucial role of amino acid bridges in constructing suitable scaffolds to preserve limbal progenitor cells. It is concluded that mild to moderate pretreatment conditions (ie, 3–10 mM L-lysine can

  19. SS-mPEG chemical modification of recombinant phospholipase C for enhanced thermal stability and catalytic efficiency.

    Science.gov (United States)

    Fang, Xian; Wang, Xueting; Li, Guiling; Zeng, Jun; Li, Jian; Liu, Jingwen

    2018-05-01

    PEGylation is one of the most promising and extensively studied strategies for improving the properties of proteins as well as enzymic physical and thermal stability. Phospholipase C, hydrolyzing the phospholipids offers tremendous applications in diverse fields. However, the poor thermal stability and higher cost of production have restricted its industrial application. This study focused on improving the stabilization of recombinant PLC by chemical modification with methoxypolyethylene glycol-Succinimidyl Succinate (SS-mPEG, MW 5000). PLC gene from isolate Bacillus cereus HSL3 was fused with SUMO, a novel small ubiquitin-related modifier expression vector and over expressed in Escherichia coli. The soluble fraction of SUMO-PLC reached 80% of the total recombinant protein. The enzyme exhibited maximum catalytic activity at 80 °C and was relatively thermostable at 40-70 °C. It showed extensive substrate specificity pattern and marked activity toward phosphatidylcholine, which made it a typical non-specific PLC for industrial purpose. SS-mPEG-PLC complex exhibited an enhanced thermal stability at 70-80 °C and the catalytic efficiency (K cat /K m ) had increased by 3.03 folds compared with free PLC. CD spectrum of SS-mPEG-PLC indicated a possible enzyme aggregation after chemical modification, which contributed to the higher thermostability of SS-mPEG-PLC. The increase of antiparallel β sheets in secondary structure also made it more stable than parallel β sheets. The presence of SS-mPEG chains on the enzyme molecule surface somewhat changed the binding rate of the substrates, leading to a significant improvement in catalytic efficiency. This study provided an insight into the addition of SS-mPEG for enhancing the industrial applications of phospholipase C at higher temperature. Copyright © 2018 Elsevier B.V. All rights reserved.

  20. Chemical characterization of solid polymer electrolyte membrane surfaces in LiFePO4 half-cells

    Science.gov (United States)

    Kyu, Thein; He, Ruixuan; Peng, Fang; Dunn, William E.; Kyu's Group Team, Dr.

    High temperature (60 °C) capacity retention of succinonitrile plasticized solid polymer electrolyte membrane (PEM) in a LiFePO4 half-cell was investigated with or without lithium bis(oxalato)borate (LiBOB) modification. Various symmetric cells and half-cells were studied under different thermal and electrochemical conditions. At room temperature cycling, the unmodified PEM in the half-cell appeared stable up to 50 cycles tested. Upon cycling at 60 °C, the capacity decays rapidly and concurrently the cell resistance increased. The chemical compositions of the solid PEM surfaces on both cathode and anode sides were analyzed. New IR bands (including those belonged to amide) were discerned on the unmodified PEM surface of the Li electrode side at 60 °C suggestive of side reaction, but no new bands develop during room temperature cycling. To our astonishment, the side reaction was effectively suppressed upon LiBOB addition (0.4 wt%) into the PEM, contributing to increased high temperature capacity retention at 60°C. Plausible mechanisms of capacity fading and improved cycling performance due to LiBOB modification are discussed.

  1. The influence of oscillating electromagnetic fields on membrane structure and function: Synthetic liposome and natural membrane bilayer systems with direct application to the controlled delivery of chemical agents

    International Nuclear Information System (INIS)

    Liburdy, R.P.; de Manincor, D.; Fingado, B.

    1989-09-01

    Investigations have been conducted to determine if an imposed electromagnetic field can influence membrane transport, and ion and drug permeability in both synthetic and natural cell membrane systems. Microwave fields enhance accumulation of sodium in the lymphocyte and induce protein shedding at Tc. Microwaves also trigger membrane permeability of liposome systems under specific field exposure conditions. Sensitivity varies in a defined way in bilayers displaying a membrane structural phase transition temperature, Tc; maximal release was observed at or near Tc. Significantly, liposome systems without a membrane phase transition were also found to experience permeability increases but, in contrast, this response was temperature independent. The above results indicate that field-enhanced drug release occurs in liposome vesicles that possess a Tc as well as non-Tc liposomes. Additional studies extend non-Tc liposome responses to the in vivo case in which microwaves trigger Gentamicin release from a liposome ''depot'' placed subcutaneously in the rat hind leg. In addition, evidence is provided that cell surface sequestered liposomes can be triggered by microwave fields to release drugs directly into target cells. 24 refs., 6 figs

  2. Incorporation of zinc for fabrication of low-cost spinel-based composite ceramic membrane support to achieve its stabilization.

    Science.gov (United States)

    Li, Lingling; Dong, Xinfa; Dong, Yingchao; Zhu, Li; You, Sheng-Jie; Wang, Ya-Fen

    2015-04-28

    In order to reduce environment risk of zinc, a spinel-based porous membrane support was prepared by the high-temperature reaction of zinc and bauxite mineral. The phase evolution process, shrinkage, porosity, mechanical property, pore size distribution, gas permeation flux and microstructure were systematically studied. The XRD results, based on a Zn/Al stoichiometric composition of 1/2, show a formation of ZnAl2O4 structure starting from 1000°C and then accomplished at 1300°C. For spinel-based composite membrane, shrinkage and porosity are mainly influenced by a combination of an expansion induced by ZnAl2O4 formation and a general densification due to amorphous liquid SiO2. The highest porosity, as high as 44%, is observed in ZnAl4 membrane support among all the investigated compositions. Compared with pure bauxite (Al), ZnAl4 composite membrane support is reinforced by ZnAl2O4 phase and inter-locked mullite crystals, which is proved by the empirical strength-porosity relationships. Also, an increase in average pore diameter and gas flux can be observed in ZnAl4. A prolonged leaching experiment reveals the zinc can be successfully incorporated into ceramic membrane support via formation of ZnAl2O4, which has substantially better resistance toward acidic attack. Copyright © 2015 Elsevier B.V. All rights reserved.

  3. New ETFE-based membrane for direct methanol fuel cell

    International Nuclear Information System (INIS)

    Saarinen, V.; Kallio, T.; Paronen, M.; Tikkanen, P.; Rauhala, E.; Kontturi, K.

    2005-01-01

    The investigated membranes are based on 35-bar μ m thick commercial poly(ethylene-alt-tetrafluoroethylene) (ETFE) films. The films were made proton conductive by means of irradiation treatment followed by sulfonation. These membranes have exceptionally low water uptake and excellent dimensional stability. The new membranes are investigated widely in a laboratory-scale direct methanol fuel cell (DMFC). The temperature range used in the fuel cell tests was 30-85-bar o C and the measurement results were compared to those of the Nafion ( R)115 membrane. Also methanol permeability through the ETFE-based membrane was measured as a function of temperature, resulting in values less than 10% of the corresponding values for Nafion ( R)115, which was considerably thicker than the experimental membrane. Methanol crossover was reported to decrease when the thickness of the membrane increases, so the ETFE-based membrane compares favourably to Nafion ( R) membranes. The maximum power densities achieved with the experimental ETFE-based membrane were about 40-65% lower than the corresponding values of the Nafion ( R)115 membrane, because of the lower conductivity and noticeably higher IR-losses. Chemical and mechanical stability of the ETFE-based membrane appeared to be promising since it was tested over 2000-bar h in the DMFC without any performance loss

  4. High pressure stability analysis and chemical bonding of Ti1-xZrxN alloy: A first principle study

    International Nuclear Information System (INIS)

    Chauhan, Mamta; Gupta, Dinesh C.

    2016-01-01

    First-principles pseudo-potential calculations have been performed to analyze the stability of Ti 1-x Zr x N alloy under high pressures. The first order phase transition from B1 to B2 phase has been observed in this alloy at high pressure. The variation of lattice parameter with the change in concentration of Zr atom in Ti 1-x Zr x N is also reported in both the phases. The calculations for density of states have been performed to understand the alloying effects on chemical bonding of Ti-Zr-N alloy.

  5. The effect of lunar soil, metal oxides on thermal and radio-chemical stability of amino acids

    International Nuclear Information System (INIS)

    Khenokh, M.A.; Lapinskaya, E.M.

    1983-01-01

    Data on study of the effect of lunar soil and some metal oxides characteristic both for land and sea basaltS of lunar sojls on thermal and radio-chemical stability of amino acids are presented. The data obtained permit to suppose that extremely small quantity of amino acids discovered in lunar soil is conditioned by their decomposition under combined effect of different types of radiation, solar wind and sharp change of temperature. Probably, the effect of soil on photochemical activity of UV-radiation of the Sun and solid-phase radiolysis is not practically observed

  6. Anatase thin film with diverse epitaxial relationship grown on yttrium stabilized zirconia substrate by chemical vapor deposition

    International Nuclear Information System (INIS)

    Miyagi, Takahira; Ogawa, Tomoyuki; Kamei, Masayuki; Wada, Yoshiki; Mitsuhashi, Takefumi; Yamazaki, Atsushi

    2003-01-01

    An anatase epitaxial thin film with diverse epitaxial relationship, YSZ (001) // anatase (001), YSZ (010) // anatase (110), was grown on a single crystalline yttrium stabilized zirconia (YSZ) (001) substrate by metal organic chemical vapor deposition (MOCVD). The full width at half maximum (FWHM) of the (004) reflection of this anatase epitaxial film was 0.4deg, and the photoluminescence of this anatase epitaxial film showed visible emission with broad spectral width and large Stokes shift at room temperature. These results indicate that this anatase epitaxial film possessed almost equal crystalline quality compared with that grown under identical growth conditions on single crystalline SrTiO 3 substrate. (author)

  7. Quantum chemical evaluation for the stability of liquid sodium containing titanium nanoparticles

    International Nuclear Information System (INIS)

    Suzuki, Ai; Inaba, Kenji; Ishizawa, Yukie; Miura, Ryuji; Hatakeyama, Nozomu; Miyamoto, Akira; Saito, Jun-ichi; Ara, Kuniaki

    2015-01-01

    Recently, liquid sodium containing titanium nanoparticles (LSnanop) have attracted considerable attention. In this study, suspension state of Ti nanoparticle in liquid sodium was quantum chemically evaluated. The atomic interaction between Ti nanoparticles and sodium atoms in the liquid sodium medium was investigated. There were some literatures which gained quantum chemical insight into a nanoparticle with the surrounding sodium atom. However, liquid sodium medium itself together with a Ti nanoparticle under the realistic temperature has not yet been investigated theoretically. To overcome the problem of conventional theoretical method, we applied computationally low-load Tight Binding Quantum Chemical Molecular Dynamics (TB-QCMD) calculation method to investigate the suspension state of the Ti nanoparticle in liquid sodium metal. (author)

  8. Invariant boxes and stability of some systems from biomathematics and chemical reactions

    International Nuclear Information System (INIS)

    Pavel, N.H.

    1984-08-01

    A general theorem on the flow-invariance of a time-dependent rectangular box with respect to a differential system is first recalled [''Analysis of some non-linear problems'' in Banach Spaces and Applications, Univ. of Iasi (Romania) (1982)]. Then a theorem applicable to the study of some differential systems from biomathematics and chemical reactions is given and proved. The theorem can be applied to enzymatic reactions, the chemical mechanism in the Belousov reaction, and the kinetic system for the chemical scheme of Hanusse of two processes with three intermediate species [in Pavel, N.H., Differential Equations, Flow-invariance and Applications, Pitman Publishing, Ltd., London (to appear)]. Next, the matrices A for which the corresponding linear system x'=Ax is component-wise positive asymptotically stable are characterized. In the Appendix a partial answer to an open problem regarding the preservation of both continuity and dissipativity in the extension of functions to a Banach space is given

  9. Stabilization of enzymatically polymerized phenolic chemicals in a model soil organic matter-free geomaterial.

    Science.gov (United States)

    Palomo, Mónica; Bhandari, Alok

    2012-01-01

    A variety of remediation methods, including contaminant transformation by peroxidase-mediated oxidative polymerization, have been proposed to manage soils and groundwater contaminated with chlorinated phenols. Phenol stabilization has been successfully observed during cross polymerization between phenolic polymers and soil organic matter (SOM) for soils with SOM >3%. This study evaluates peroxidase-mediated transformation and removal of 2,4-dichlorophenol (DCP) from an aqueous phase in contact with a natural geomaterial modified to contain negligible (soils with higher SOM. The SOM-free sorbent was generated by removing SOM using a NaOCl oxidation. When horseradish peroxidase (HRP) was used to induce polymerization of DCP, the soil-water phase distribution relationship (PDR) of DCP polymerization products (DPP) was complete within 1 d and PDRs did not significantly change over the 28 d of study. The conversion of DCP to DPP was close to 95% efficient. Extractable solute consisted entirely of DPP with 5% or less of unreacted DCP. The aqueous extractability of DPP from SOM-free geomaterial decreased at longer contact times and at smaller residual aqueous concentrations of DPP. DCP stabilization appeared to have resulted from a combination of sorption, precipitation, and ligand exchange between oligomeric products and the exposed mineral surfaces. Modification of the mineral surface through coverage with DPP enhanced the time-dependent retention of the oligomers. DPP stabilization in SOM-free geomaterial was comparable with that reported in the literature with soil containing SOM contents >1%. Results from this study suggest that the effectiveness of HRP-mediated stabilization of phenolic compounds not only depends on the cross-coupling with SOM, but also on the modification of the surface of the sorbent that can augment affinity with oligomers and enhance stabilization. Coverage of the mineral surface by phenolic oligomers may be analogous to SOM that can potentially

  10. Evaluation of quantum-chemical methods of radiolysis stability for macromolecular structures

    International Nuclear Information System (INIS)

    Postolache, Cristian; Matei, Lidia

    2005-01-01

    The behavior of macromolecular structures in ionising fields was analyzed by quantum-chemical methods. In this study the primary radiolytic effect was analyzed using a two-step radiolytic mechanism: a) ionisation of molecule and spatial redistribution of atoms in order to reach a minimum value of energy, characteristic to the quantum state; b) neutralisation of the molecule by electron capture and its rapid dissociation into free radicals. Chemical bonds suspected to break are located in the distribution region of LUMO orbital and have minimal homolytic dissociation energies. Representative polymer structures (polyethylene, polypropylene, polystyrene, poly α and β polystyrene, polyisobutylene, polytetrafluoroethylene, poly methylsiloxanes) were analyzed. (authors)

  11. Chemical functionalization and stabilization of type I collagen with organic tanning agents

    International Nuclear Information System (INIS)

    Albu, Madalina Georgiana; Deselnicu, Viorica; Ioannidis, Ioannis; Deselnicu, Dana; Chelaru, Ciprian

    2015-01-01

    We investigated the interactions between selected organic tanning agents and type I fibrillar collagen as a model fibrillar substrate to enable the fast direct evaluation and validation of interpretations of tanning activity. Type I fibrillar collagen (1%) as gel was used as substrate of tanning and tannic acid, resorcinol- and melamine-formaldehyde and their combination at three concentrations as crosslinking agents (tannins). To evaluate the stability of collagen during tanning, the crosslinked gels at 2.8, 4.5 and 9.0 pHs were freeze-dried as discs which were characterized by FTIR, shrinkage temperature, enzymatic degradation and optical microscopy, and the results were validated by statistical analyses. The best stability was given by combinations between resorcinol- and melamine-formaldehyde at isoelectric pH

  12. Chemical functionalization and stabilization of type I collagen with organic tanning agents

    Energy Technology Data Exchange (ETDEWEB)

    Albu, Madalina Georgiana; Deselnicu, Viorica; Ioannidis, Ioannis; Deselnicu, Dana; Chelaru, Ciprian [Leather and Footwear Research Institute, Bucharest (Romania)

    2015-02-15

    We investigated the interactions between selected organic tanning agents and type I fibrillar collagen as a model fibrillar substrate to enable the fast direct evaluation and validation of interpretations of tanning activity. Type I fibrillar collagen (1%) as gel was used as substrate of tanning and tannic acid, resorcinol- and melamine-formaldehyde and their combination at three concentrations as crosslinking agents (tannins). To evaluate the stability of collagen during tanning, the crosslinked gels at 2.8, 4.5 and 9.0 pHs were freeze-dried as discs which were characterized by FTIR, shrinkage temperature, enzymatic degradation and optical microscopy, and the results were validated by statistical analyses. The best stability was given by combinations between resorcinol- and melamine-formaldehyde at isoelectric pH.

  13. Chemical stabilization of metals and arsenic in contaminated soils using oxides--a review.

    Science.gov (United States)

    Komárek, Michael; Vaněk, Aleš; Ettler, Vojtěch

    2013-01-01

    Oxides and their precursors have been extensively studied, either singly or in combination with other amendments promoting sorption, for in situ stabilization of metals and As in contaminated soils. This remediation option aims at reducing the available fraction of metal(loid)s, notably in the root zone, and thus lowering the risks associated with their leaching, ecotoxicity, plant uptake and human exposure. This review summarizes literature data on mechanisms involved in the immobilization process and presents results from laboratory and field experiments, including the subsequent influence on higher plants and aided phytostabilization. Despite the partial successes in the field, recent knowledge highlights the importance of long-term and large-scale field studies evaluating the stability of the oxide-based amendments in the treated soils and their efficiency in the long-term. Copyright © 2012 Elsevier Ltd. All rights reserved.

  14. A Catalytically Active Membrane Reactor for Fast, Highly Exothermic, Heterogeneous Gas Reactions. A Pilot Plant Study

    NARCIS (Netherlands)

    Veldsink, Jan W.; Versteeg, Geert F.; Swaaij, Wim P.M. van

    1995-01-01

    Membrane reactors have been frequently studied because of their ability to combine chemical activity and separation properties into one device. Due to their thermal stability and mechanical strength, ceramic membranes are preferred over polymeric ones, but small transmembrane fluxes obstruct a

  15. A catalytically membrane reactor for fast, highly exothermic, heterogeneous gas reactions : a pilot plant study

    NARCIS (Netherlands)

    Veldsink, J.W.; Veldsink, J.W.; Versteeg, Geert; van Swaaij, Willibrordus Petrus Maria

    1995-01-01

    Membrane reactors have been frequently studied because of their ability to combine chemical activity and separation properties into one device. Due to their thermal stability and mechanical strength, ceramic membranes are preferred over polymeric ones, but small transmembrane fluxes obstruct a

  16. Strength degradation and failure limits of dense and porous ceramic membrane materials

    DEFF Research Database (Denmark)

    Pećanac, G.; Foghmoes, Søren Preben Vagn; Lipińska-Chwałek, M.

    2013-01-01

    Thin dense membrane layers, mechanically supported by porous substrates, are considered as the most efficient designs for oxygen supply units used in Oxy-fuel processes and membrane reactors. Based on the favorable permeation properties and chemical stability, several materials were suggested...

  17. Covalently Cross-Linked Sulfone Polybenzimidazole Membranes with Poly(Vinylbenzyl Chloride) for Fuel Cell Applications

    DEFF Research Database (Denmark)

    Yang, Jingshuai; Aili, David; Li, Qingfeng

    2013-01-01

    Covalently cross-linked polymer membranes were fabricated from poly(aryl sulfone benzimidazole) (SO(2) PBI) and poly(vinylbenzyl chloride) (PVBCl) as electrolytes for high-temperature proton-exchange-membrane fuel cells. The cross-linking imparted organo insolubility and chemical stability against...

  18. Organic Redox Species in Aqueous Flow Batteries: Redox Potentials, Chemical Stability and Solubility

    OpenAIRE

    Kristina Wedege; Emil Dražević; Denes Konya; Anders Bentien

    2016-01-01

    Organic molecules are currently investigated as redox species for aqueous low-cost redox flow batteries (RFBs). The envisioned features of using organic redox species are low cost and increased flexibility with respect to tailoring redox potential and solubility from molecular engineering of side groups on the organic redox-active species. In this paper 33, mainly quinone-based, compounds are studied experimentially in terms of pH dependent redox potential, solubility and stability, combined ...

  19. Physical and Chemical Stability of Urapidil in 0.9% Sodium Chloride in Elastomeric Infusion Pump.

    Science.gov (United States)

    Tomasello, Cristina; Leggieri, Anna; Rabbia, Franco; Veglio, Franco; Baietto, Lorena; Fulcheri, Chiara; De Nicolò, Amedeo; De Perri, Giovanni; D'Avolio, Antonio

    2016-01-01

    Urapidil is an antihypertensive agent, usually administered through intravenous bolus injection, slow-intravenous infusion, or continuous-drug infusion by perfusor. Since to date no evidences are available on drug stability in elastomeric pumps, patients have to be hospitalized. The purpose of this study was to validate an ultra-performance liquid chromatographic method to evaluate urapidil stability in an elastomeric infusion pump, in order to allow continuous infusion as home-care treatment. Analyses were conducted by diluting urapidil in an elastomeric pump. Two concentrations were evaluated: 1.6 mg/mL and 3.3 mg/mL. For the analyses, a reverse-phase ultra-performance liquid chromatographic- photodiode array detection instrument was used. Stressed degradation, pH changes, and visual clarity were used as stability indicators up to 10 days after urapidil solution preparation. The drug showed no more than 5% degradation during the test period at room temperature. No pH changes and no evidences of incompatibility were observed. Stress tests resulted in appreciable observation of degradation products. Considering the observed mean values, urapidil hydrochloride in sodium chloride 0.9% in elastomeric infusion pumps is stable for at least 10 days. These results indicate that this treatment could be administered at home for a prolonged duration (at least 7 days) with a satisfactory response. Copyright© by International Journal of Pharmaceutical Compounding, Inc.

  20. Influence of chemical treatment on dimensional stability of narrow-leaved ash - part one: Tangential swelling

    Directory of Open Access Journals (Sweden)

    Popović Jasmina

    2012-01-01

    Full Text Available Dimensional change in wood occurs with the change in hygroscopic moisture content, as a consequence of available hydroxyl groups in wood constituents, allowing for the hydrogen bonding with water molecules. Various pretreatments of wood material are being frequently applied in the wood processing industry. One of the main effects of such processes is the hydrolysis of hemicelluloses, which is the main carrier of the free hydroxyl groups in wood material. Hence, the influence of water treatment and the acetic acid treatment on dimensional stability of narrow-leaved ash (Fraxinus angustifolia Vahl. ssp. Pannonica Soó & Simon were examined in this paper. Duration of treatments was 1h, 2h, 3h and 4h for both solvents. In addition the acetic acid was separately used in concentrations of 3% and 6%. Dimensional stability of the control (referent and treated sample groups were tested on oven dried samples which were consequently submerged in the distilled water during 32 days. The increase of dimensional stability of narrow-leaved ash was achieved with all of the three treatments (one treatment with water and the two with acetic acid solutions. Simultaneously, it was noticed that the results of water uptake and tangential swelling were not significantly affected by the duration (length of the treatments. [Projekat Ministarstva nauke Republike Srbije, br. TP-031041

  1. CO2 separation from biogas with ceramic membranes

    International Nuclear Information System (INIS)

    Fassauer, Burkhardt; Richter, Hannes; Schwarz, Bjoern; Reger-Wagner, Norman; Kaemnitz, Susanne; Lubenau, Udo; Mothes, Raimund

    2015-01-01

    Biogas contains after the production of up to 55% CO 2 . In order to use biogas as a fuel or to feed it into the natural gas network, it must be purified before. Adsorption and scrubbing processes are primarily used technically. Membrane processes offer the advantage of continuous operation and a simple modular and flexible system design, which imply relatively low investment costs and low energy needs. Moreover, membrane systems can be started up and shut down quickly without any problems. Ceramic membranes are characterised by high stability (thermal, chemical, mechanical) and very high flows in comparison to polymeric membranes. [de

  2. Separation of tritiated water from water using composite membranes

    International Nuclear Information System (INIS)

    Duncan, J.; Nelson, D.

    1996-01-01

    Polymeric composite membranes are being developed to remove tritium from contaminated water at DOE sites. Industrial membrane systems are being developed that have proven to be energy efficient, and membrane technologies such as reverse-osmosis have been well developed for desalination and other industrial/municipal applications. Aromatic polyphosphazene membranes are being investigated because they have excellent radiological, thermal, and chemical stability. The FY 1996 effort is directed toward delineating a potential mechanism, providing a statistical approach to data acquisition, refining a mass balance, and designing a staged array module

  3. Mechanical properties and chemical stability of pivalolactone-based poly(ether ester)s

    NARCIS (Netherlands)

    Tijsma, E.J.; Tijsma, E.J.; van der Does, L.; Bantjes, A.; Bantjes, A.; Vulic, I.

    1994-01-01

    The processing, mechanical and chemical properties of poly(ether ester)s, prepared from pivalolactone (PVL), 1,4-butanediol (4G) and dimethyl terephthalate (DMT), were studied. The poly(ether ester)s could easily be processed by injection moulding, owing to their favourable rheological and thermal

  4. Validation and refinement of chemical stabilization procedures for pavement subgrade soils in Oklahoma : volume I.

    Science.gov (United States)

    2011-07-01

    Additions of byproduct chemicals, such as fly ash or cement kiln dust, have been shown to increase the unconfined compression strength (UCS) of soils. To be considered effective, the soil must exhibit a strength increase of at least 50 psi. Many curr...

  5. Stability fields of smectites and illites as a function of temperature and chemical composition

    International Nuclear Information System (INIS)

    Tardy, Y.; Duplay, J.; Fritz, B.; Strasbourg-1 Univ., 67

    1987-04-01

    A thermodynamic ideal solid solution analogue is proposed which accounts the correlations which clearly reflect the temperatures at which the nonmineralic population are supposed to have been formed. The solid solution is considered, at a particle scale, as an ideal mixture of individual layers, weakly bent each to the next. Each layer presents the chemical composition of a given end member, so that the proportions of the different end members change from one particle to another. Considering one particle of a given chemical composition, the multipole solid solution theory allows to calculate the wheighted contributions of each end member into the ideal clay solid solution along with the chemical composition of the aqueous solutions in equilibrium with the considered particle in its independent microenvironment. This model is able to predict the nature of the chemical correlations which are expected, at a given temperature, within a given population. This model is also applied to the prediction of the temperature required for the conversion of smectite into illite during the burial diagenesis. (orig./HP)

  6. STABILITY OF MFI ZEOLITE-FILLED PDMS MEMBRANES DURING PERVAPORATIVE ETHANOL RECOVERY FROM AQUEOUS MIXTURES CONTAINING ACETIC ACID

    Science.gov (United States)

    Pervaporation is potentially a cost-effective means of recovering biofuels, such as ethanol, from biomass fermentation broths for small- to medium-scale applications (~2 - 20 million liters per year). Hydrophobic zeolite-filled polydimethylsiloxane (PDMS) membranes have been sho...

  7. Stability of radicals in electron-irradiated fluoropolymer film for the preparation ofgraft copolymer fuel cell electrolyte membranes

    DEFF Research Database (Denmark)

    Larsen, Mikkel Juul; Ma, Yue; Qian, Huan

    2010-01-01

    The content of radicals in the base polymer film before and after grafting is an important issue in theproduction and use of membranes for electrochemical devices by radiation grafting. In this work a methodhas been developed for determination of relative radical content in fluoropolymer films us...

  8. Isoparaffin diluents for tri-n-butyl phosphate. Chemical, radiation-chemical stability, effect on solvent extraction of tetravalet plutonium and thorium

    International Nuclear Information System (INIS)

    Renard, Eh.V.; Pyatibratov, Yu.P.; Neumoev, N.V.

    1988-01-01

    45-90% conversion degree of n-paraffin into branched isoparaffin with mono- and dimethyl structure is achieved by means of catalytic hydroisomerization of n-paraffin raw material in reactor with alumoplatinum catalyser. Isoparaffin (99%) concentrates with constant molecular mass from iso-C 10 to iso-C 15 are produced of a batch of deeply isomerized n-paraffins. Plutonium and thorum nitrate solubility in 30% TBP solutions in iso-paraffins (iso-paraffin mixtures with similar C atom number) increases with the reduction of iso-paraffin molecular mass; system with 30% TBP in isodecane mixture is practically not stratified (∼ 104 g Pu/l, 22-25 deg C). By the main requirements to diluents for radiochemical extraction operations, including density, viscosity, boiling point flashed and freezines, chemical and radiation stability, radioruthenium and radiozirconium confinement systems, synthetic isoparaffin-containing solvents are as good as n-paraffins

  9. College Students' Conceptions of Chemical Stability: The Widespread Adoption of a Heuristic Rule out of Context and beyond Its Range of Application

    Science.gov (United States)

    Taber, Keith S.

    2009-01-01

    This paper reports evidence that learners commonly develop a notion of chemical stability that, whilst drawing upon ideas taught in the curriculum, is nevertheless inconsistent with basic scientific principles. A series of related small-scale studies show that many college-level students consider a chemical species with an octet structure, or a…

  10. Membrane Stabilization and Detoxification of Acetaminophen-Mediated Oxidative Onslaughts in the Kidneys of Wistar Rats by Standardized Fraction of Zea mays L. (Poaceae), Stigma maydis

    Science.gov (United States)

    Sabiu, S.; O'Neill, F. H.

    2016-01-01

    This study evaluated membrane stabilization and detoxification potential of ethyl acetate fraction of Zea mays L., Stigma maydis in acetaminophen-induced oxidative onslaughts in the kidneys of Wistar rats. Nephrotoxic rats were orally pre- and posttreated with the fraction and vitamin C for 14 days. Kidney function, antioxidative and histological analyses were thereafter evaluated. The acetaminophen-mediated significant elevations in the serum concentrations of creatinine, urea, uric acid, sodium, potassium, and tissue levels of oxidized glutathione, protein-oxidized products, lipid peroxidized products, and fragmented DNA were dose-dependently assuaged in the fraction-treated animals. The fraction also markedly improved creatinine clearance rate, glutathione, and calcium concentrations as well as activities of superoxide dismutase, catalase, glutathione reductase, and glutathione peroxidase in the nephrotoxic rats. These improvements may be attributed to the antioxidative and membrane stabilization activities of the fraction. The observed effects compared favorably with that of vitamin C and are informative of the fraction's ability to prevent progression of renal pathological conditions and preserve kidney functions as evidently supported by the histological analysis. Although the effects were prominently exhibited in the fraction-pretreated groups, the overall data from the present findings suggest that the fraction could prevent or extenuate acetaminophen-mediated oxidative renal damage via fortification of antioxidant defense mechanisms. PMID:27579048

  11. Expression, stabilization and purification of membrane proteins via diverse protein synthesis systems and detergents involving cell-free associated with self-assembly peptide surfactants.

    Science.gov (United States)

    Zheng, Xuan; Dong, Shuangshuang; Zheng, Jie; Li, Duanhua; Li, Feng; Luo, Zhongli

    2014-01-01

    G-protein coupled receptors (GPCRs) are involved in regulating most of physiological actions and metabolism in the bodies, which have become most frequently addressed therapeutic targets for various disorders and diseases. Purified GPCR-based drug discoveries have become routine that approaches to structural study, novel biophysical and biochemical function analyses. However, several bottlenecks that GPCR-directed drugs need to conquer the problems including overexpression, solubilization, and purification as well as stabilization. The breakthroughs are to obtain efficient protein yield and stabilize their functional conformation which are both urgently requiring of effective protein synthesis system methods and optimal surfactants. Cell-free protein synthesis system is superior to the high yields and post-translation modifications, and early signs of self-assembly peptide detergents also emerged to superiority in purification of membrane proteins. We herein focus several predominant protein synthesis systems and surfactants involving the novel peptide detergents, and uncover the advantages of cell-free protein synthesis system with self-assembling peptide detergents in purification of functional GPCRs. This review is useful to further study in membrane proteins as well as the new drug exploration. Copyright © 2014 Elsevier Inc. All rights reserved.

  12. Membrane Stabilization and Detoxification of Acetaminophen-Mediated Oxidative Onslaughts in the Kidneys of Wistar Rats by Standardized Fraction of Zea mays L. (Poaceae, Stigma maydis

    Directory of Open Access Journals (Sweden)

    S. Sabiu

    2016-01-01

    Full Text Available This study evaluated membrane stabilization and detoxification potential of ethyl acetate fraction of Zea mays L., Stigma maydis in acetaminophen-induced oxidative onslaughts in the kidneys of Wistar rats. Nephrotoxic rats were orally pre- and posttreated with the fraction and vitamin C for 14 days. Kidney function, antioxidative and histological analyses were thereafter evaluated. The acetaminophen-mediated significant elevations in the serum concentrations of creatinine, urea, uric acid, sodium, potassium, and tissue levels of oxidized glutathione, protein-oxidized products, lipid peroxidized products, and fragmented DNA were dose-dependently assuaged in the fraction-treated animals. The fraction also markedly improved creatinine clearance rate, glutathione, and calcium concentrations as well as activities of superoxide dismutase, catalase, glutathione reductase, and glutathione peroxidase in the nephrotoxic rats. These improvements may be attributed to the antioxidative and membrane stabilization activities of the fraction. The observed effects compared favorably with that of vitamin C and are informative of the fraction’s ability to prevent progression of renal pathological conditions and preserve kidney functions as evidently supported by the histological analysis. Although the effects were prominently exhibited in the fraction-pretreated groups, the overall data from the present findings suggest that the fraction could prevent or extenuate acetaminophen-mediated oxidative renal damage via fortification of antioxidant defense mechanisms.

  13. Conserved amino acids within the N-terminus of the West Nile virus NS4A protein contribute to virus replication, protein stability and membrane proliferation

    International Nuclear Information System (INIS)

    Ambrose, R.L.; Mackenzie, J.M.

    2015-01-01

    The West Nile virus strain Kunjin virus (WNV KUN ) NS4A protein is a multifunctional protein involved in many aspects of the virus life-cycle and is a major component of the WNV KUN replication complex (RC). Previously we identified a conserved region in the C-terminus of NS4A regulating proteolytic processing and RC assembly, and now investigate key conserved residues in the N-terminus of NS4A and their contribution to WNV KUN replication. Mutation of P13 completely ablated replication, whereas, mutation of P48 and D49, near the first transmembrane helix, and G66 within the helix, showed variable defects in replication, virion secretion and membrane proliferation. Intriguingly, the P48 and G66 NS4A mutants resulted in specific proteasome depletion of NS4A that could in part be rescued with a proteasome inhibitor. Our results suggest that the N-terminus of NS4A contributes to correct folding and stability, essential for facilitating the essential roles of NS4A during replication. - Highlights: • Mutation of Proline13 of the WNV NS4A protein is lethal to replication. • 1st TMB helix of NS4A contributes to protein stability and membrane remodelling. • Unstable mutants of NS4A can be rescued with a proteasome inhibitor. • This study (and of others) contributes to a functional mapping of the NS4A protein

  14. Identification of new SSR markers linked to leaf chlorophyll content, flag leaf senescence and cell membrane stability traits in wheat under water stressed condition.

    Science.gov (United States)

    Barakat, Mohamed N; Saleh, Mohamed; Al-Doss, Abdullah A; Moustafa, Khaled A; Elshafei, Adel A; Al-Qurainy, Fahed H

    2015-03-01

    Segregating F4 families from the cross between drought sensitive (Yecora Rojo) and drought tolerant (Pavon 76) genotypes were made to identify SSR markers linked to leaf chlorophyll content, flag leaf senescence and cell membrane stability traits in wheat (Triticum ae