The Experts below are selected from a list of 110331 Experts worldwide ranked by ideXlab platform

Rafiuddin - One of the best experts on this subject based on the ideXlab platform.

  • Preparation, electrochemical characterization and antibacterial study of polystyrene-based magnesium–strontium phosphate composite Membrane
    Materials Science and Engineering: C, 2012
    Co-Authors: Mohammad Mujahid Ali Khan, Rafiuddin
    Abstract:

    Abstract The electrochemical characterizations of polystyrene-based magnesium–strontium phosphate (MSP) composite Membrane have been worked on, as a function of Membrane thickness, porosity and moisture content etc. Polystyrene-based magnesium–strontium phosphate composite Membrane was characterized by XRD, FTIR, SEM, and antibacterial studies. The Membrane was found to be crystalline in nature with uniform arrangement of particles, no sign of visible cracks and shows excellent inhibitory results against Escherichia coli and Pseudomonas aeruginosa bacteria. The Membrane potentials of inorganic Membrane were measured with uni-univalent electrolytes solution using saturated calomel electrodes and followed the order LiCl > NaCl > KCl, thus, the Membrane was found to be cation selective. Membrane potential data have been used to calculate transport number, mobility ratio, distribution coefficient, charge effectiveness, and also to derive the fixed-charge density which is a central parameter governing the Membrane phenomena by utilizing the Teorell, Meyer, and Sievers method. The order of surface charge density for uni-univalent electrolytes solution was found to be LiCl

  • Synthesis, electrochemical characterization, antibacterial study and evaluation of fixed charge density of polystyrene based calcium-strontium phosphate composite Membrane
    Desalination, 2012
    Co-Authors: Mohammad Mujahid Ali Khan, Rafiuddin
    Abstract:

    Abstract The present work demonstrates the electrochemical characterizations of polystyrene based calcium–strontium phosphate composite Membranes prepared by sol–gel process. Polystyrene based magnesium-strontium (CSP) composite Membrane was characterized by XRD, FTIR, SEM, and antibacterial studies. The Membrane was found to be crystalline in nature with uniform arrangement of particles indicating no sign of visible cracks and showed good inhibitory effects against gram positive as well as gram negative bacteria. The IR spectra confirm the binding of the composites with the polystyrene. The observed Membrane potential of polystyrene based calcium–strontium phosphate composite Membrane were measured with uni-univalent electrolytes solutions using saturated calomel electrodes and followed the order LiCl > NaCl > KCl. Thus, the Membrane was found to be Cation-Selective. Membrane potential data have been used to calculate transport number, mobility ratio, distribution coefficient, charge effectiveness, and also to derive the fixed charge density which is a key parameter to govern the Membrane phenomena by utilizing Teorell, Meyer, and Sievers method. The order of surface charge density for uni-univalent electrolytes solution was found to be KCl > NaCl > LiCl.

Arthur Yelon - One of the best experts on this subject based on the ideXlab platform.

  • Sodium salt-splitting performance of a novel ceramic-polymer composite Cation-Selective Membrane
    Journal of The Electrochemical Society, 2002
    Co-Authors: L. M. Cormier, S. T. Bah, M. Paleologou, Michel Meunier, S. Guetre, Arthur Yelon
    Abstract:

    The salt splitting performance of an electrolysis cell incorporating a novel composite Membrane consisting of a thin film of an amorphous ceramic with NASICON composition (Na 1+x Zr 2 Si x PO 3-x , 0≤x≤3) deposited on commercial Cation-Selective polymeric Membranes was evaluated. We have investigated how the ceramic film thickness and the technique of deposition affected the base current efficiency (BCE) for the production of sodium hydroxide from sodium sulfate. It was found that when full coverage of the polymeric substrate was achieved, the ceramic film improved the salt-splitting performance of the polymeric Membrane, even when localized surface defects were present. The study showed that the BCE of the electrolysis cell was the same whether the Cation-Selective composite Membrane used was formed by pulsed laser deposition or by sputtering. Operating the cell above room temperature, and at a high anolyte concentration increased the base current efficiency for sodium hydroxide production.

  • Evaluation of a Ceramic‐Polymer Composite Cation‐Selective Membrane for Sodium Salt Splitting
    Journal of The Electrochemical Society, 1999
    Co-Authors: F. Girard, Ricardo Izquierdo, E. Quenneville, S. T. Bah, M. Paleologou, Michel Meunier, D. Ivanov, Arthur Yelon
    Abstract:

    A RAIPORE polymeric Cation-Selective Membrane was modified by deposition of a thin film of NASICON, a sodium superionic conducting ceramic, using pulsed laser deposition. The composite Membrane was incorporated into an electrolysis system for the production of sodium hydroxide and sulfuric acid from sodium sulfate. Its performance was compared to the unmodified polymeric base Membrane. The composite Membrane showed a significantly higher selectivity for sodium over hydrogen ions compared to the unmodified polymeric base Membrane, resulting in a higher current efficiency and a lower energy consumption for the production of sodium hydroxide. The composite Membrane was also found to be more resistant to fouling by ferric ion as compared to the polymeric Membrane. Neither Membrane was fouled by calcium or magnesium. The selectivity of the composite Membrane for sodium over potassium ions was not found to improve by the deposition of the ceramic layer.

Azzedine Elmidaoui - One of the best experts on this subject based on the ideXlab platform.

  • transport and separation of ag and zn 2 by donnan dialysis through a monovalent cation selective Membrane
    Talanta, 1998
    Co-Authors: A.t. Cherif, Jean Molenat, Claude Gavach, Azzedine Elmidaoui
    Abstract:

    Abstract Donnan Dialysis of Ag+ and Zn2+ was investigated through a cation exchange Membrane (CMS Neosepta) when a proton concentration difference was maintained between the two sides of the Membrane. Developed for the production of brine from sea water, CMS Neosepta showed a higher permeability to monovalent than to bivalent cations. Several physico-chemical parameters have been determined (electrical resistance, Membrane potential, sorption of electrolytes, Zn2+ and Ag+ diffusion coefficients). The flux of Ag+ and the diffusion potential in the Membrane increase with HNO3 concentrations. Ag+ and Zn2+ can be separated because of the preferential Membrane transfer for Ag+.

  • Transport and separation of Ag(+) and Zn(2+) by donnan dialysis through a monovalent cation selective Membrane.
    Talanta, 1998
    Co-Authors: A.t. Cherif, Jean Molenat, Claude Gavach, Azzedine Elmidaoui
    Abstract:

    Abstract Donnan Dialysis of Ag+ and Zn2+ was investigated through a cation exchange Membrane (CMS Neosepta) when a proton concentration difference was maintained between the two sides of the Membrane. Developed for the production of brine from sea water, CMS Neosepta showed a higher permeability to monovalent than to bivalent cations. Several physico-chemical parameters have been determined (electrical resistance, Membrane potential, sorption of electrolytes, Zn2+ and Ag+ diffusion coefficients). The flux of Ag+ and the diffusion potential in the Membrane increase with HNO3 concentrations. Ag+ and Zn2+ can be separated because of the preferential Membrane transfer for Ag+.

Mohammad Mujahid Ali Khan - One of the best experts on this subject based on the ideXlab platform.

  • Preparation, electrochemical characterization and antibacterial study of polystyrene-based magnesium–strontium phosphate composite Membrane
    Materials Science and Engineering: C, 2012
    Co-Authors: Mohammad Mujahid Ali Khan, Rafiuddin
    Abstract:

    Abstract The electrochemical characterizations of polystyrene-based magnesium–strontium phosphate (MSP) composite Membrane have been worked on, as a function of Membrane thickness, porosity and moisture content etc. Polystyrene-based magnesium–strontium phosphate composite Membrane was characterized by XRD, FTIR, SEM, and antibacterial studies. The Membrane was found to be crystalline in nature with uniform arrangement of particles, no sign of visible cracks and shows excellent inhibitory results against Escherichia coli and Pseudomonas aeruginosa bacteria. The Membrane potentials of inorganic Membrane were measured with uni-univalent electrolytes solution using saturated calomel electrodes and followed the order LiCl > NaCl > KCl, thus, the Membrane was found to be cation selective. Membrane potential data have been used to calculate transport number, mobility ratio, distribution coefficient, charge effectiveness, and also to derive the fixed-charge density which is a central parameter governing the Membrane phenomena by utilizing the Teorell, Meyer, and Sievers method. The order of surface charge density for uni-univalent electrolytes solution was found to be LiCl

  • Synthesis, electrochemical characterization, antibacterial study and evaluation of fixed charge density of polystyrene based calcium-strontium phosphate composite Membrane
    Desalination, 2012
    Co-Authors: Mohammad Mujahid Ali Khan, Rafiuddin
    Abstract:

    Abstract The present work demonstrates the electrochemical characterizations of polystyrene based calcium–strontium phosphate composite Membranes prepared by sol–gel process. Polystyrene based magnesium-strontium (CSP) composite Membrane was characterized by XRD, FTIR, SEM, and antibacterial studies. The Membrane was found to be crystalline in nature with uniform arrangement of particles indicating no sign of visible cracks and showed good inhibitory effects against gram positive as well as gram negative bacteria. The IR spectra confirm the binding of the composites with the polystyrene. The observed Membrane potential of polystyrene based calcium–strontium phosphate composite Membrane were measured with uni-univalent electrolytes solutions using saturated calomel electrodes and followed the order LiCl > NaCl > KCl. Thus, the Membrane was found to be Cation-Selective. Membrane potential data have been used to calculate transport number, mobility ratio, distribution coefficient, charge effectiveness, and also to derive the fixed charge density which is a key parameter to govern the Membrane phenomena by utilizing Teorell, Meyer, and Sievers method. The order of surface charge density for uni-univalent electrolytes solution was found to be KCl > NaCl > LiCl.

Mayumi Iijima - One of the best experts on this subject based on the ideXlab platform.

  • Tooth Enamel Proteins Enamelin and Amelogenin Cooperate To Regulate the Growth Morphology of Octacalcium Phosphate Crystals
    Crystal growth & design, 2010
    Co-Authors: Mayumi Iijima, Daming Fan, Keith M. Bromley, Zhi Sun, Janet Moradian-oldak
    Abstract:

    To examine the hypothetical cooperative role of enamelin and amelogenin in controlling the growth morphology of enamel crystals in the postsecretory stage, we applied a cation selective Membrane sy...

  • Creation of a composite of collagen and OCP crystals with large morphological anisotropy
    Journal of the Ceramic Society of Japan, 2008
    Co-Authors: Mayumi Iijima, Nobukazu Wakamatu, Hideo Kamemizu, Masanori Adachi, Yutaka Doi
    Abstract:

    Collagen and octacalcium phosphate (OCP) crystals of micrometer size with anisotropic morphology were combined under physiological temperature and pH. OCP crystals elongated in the c-axis direction were grown in a reaction chamber where diffusion was controlled by a cation selective Membrane. The size of crystal used was 40-50 μm in length, about 2 μm in width and aspect ratio of around 20-25. Atelocollagen was reconstituted and cross-linked in the presence of the crystals at 37°C for 20-48 h under stirring. Despite stirring and mixing during fabrication process, the long crystals assembled with reconstituted collagen fibers and arranged more or less parallel to each other along the collagen fibers. This suggested that OCP crystals and collagen fibers assembled through some interaction, by which crystals stayed on/between collagen fibers during fabrication process. Collagen content of resultant composites was arbitrarily changeable in the range of 20-90% by weight. Thus, the composite of long OCP crystals and collagen was newly designed for future application as a bone substitute material.

  • control of apatite crystal growth in a fluoride containing amelogenin rich matrix
    Biomaterials, 2005
    Co-Authors: Mayumi Iijima, Janet Moradianoldak
    Abstract:

    Abstract To study how crystal growth in dental enamel is controlled by the components of the extracellular matrix, we investigated the functional roles of amelogenins and fluoride ions in apatite formation occurring through an octacalcium phosphate (OCP)-precursor pathway. Using a cation selective Membrane system as a model of tooth enamel formation, we evaluated the resulting mineral habit grown in native porcine amelogenins and fluoride ions. In the absence of amelogenin and in the presence of 1 or 2 ppm F, we obtained OCP+apatite and apatite, respectively. Without amelogenins, the crystals were hexagonal prisms and cones with diameters of ∼100–200 nm. In the presence of 10% amelogenins and in the absence of fluoride, rod-like OCP with a diameter of 35 nm were obtained. Remarkably, a combination of amelogenin and fluoride created the formation of rod-like apatite crystals with dimensions similar to the former crystals. These observations indicate a cooperative role of amelogenin and fluoride in the regulation of habit, size orientation and phase of the calcium-phosphate crystals, resulting in the formation of fine rod-like apatite whose habit and orientation were similar to that of authentic tooth enamel crystals. The significant modulating effect of the amelogenin matrix combined with fluoride ions suggests the potential for this artificial system to contribute to the engineering of novel enamel-like biomaterials in vitro.

  • Effects of the Ca2+ and PO43− ion flow on the lengthwise growth of octacalcium phosphate in a model system of enamel crystal formation with controlled ionic diffusion
    Journal of Crystal Growth, 2001
    Co-Authors: Mayumi Iijima, Kenji Hayashi, Yutaka Moriwaki
    Abstract:

    Abstract An amount of Ca 2+ and PO 4 3− ions transported into the enamel matrix change during tooth enamel crystals formation. Effects of the Ca 2+ and PO 4 3− ion flow on the lengthwise growth of octacalcium phosphate were studied at 37°C and at pH 6.5 in a model system of tooth enamel formation, where a cation selective Membrane and a dialysis Membrane were used to control the ionic diffusion. An amount of Ca 2+ and PO 4 3− ions that flow into the reaction space between the Membranes was changed by using 5, 10, 30 mM Ca and PO 4 solutions as ionic sources. The length increased while the width decreased with an increase in concentration of Ca and/or PO 4 solutions. As a result, the length to width ( L / W ) ratio increased and the width to thickness ( W / T ) ratio decreased with an increase in concentration, resulting in narrower and longer ribbon-like crystals. It was suggested that growth of enamel crystals is, in part, affected by the change in the amount of Ca 2+ and PO 4 3− ions, that flow into the enamel matrix.

  • Amelogenin Nanospheres Modulate Crystal Habit of Octacalcium Phosphate and Hydroxyapatite Crystals in In Vitro Model Systems
    MRS Proceedings, 2000
    Co-Authors: Janet Moradian-oldak, H.b. Wen, Alan G. Fincham, Mayumi Iijima
    Abstract:

    This paper is a short review of recent studies, which were undertaken to investigate interactions of amelogenin with octacalcium phosphate (OCP), and apatite. OCP crystals were grown using two independent experimental systems; (a) in a 10% gelatin gel, containing 0-2% amelogenin, where the crystals were formed in a double-diffusion chamber, and (b) in a 10% pure amelogenin gel, where crystal growth took place in between a Cation-Selective and a dialysis Membrane. Apatite crystals were grown from a supersaturated calcifying solution on a bioactive glass in the absence (SCS B ) and the presence of amelogenin (SCSrM179). It was found that OCP crystals formed in 10% gelatin gel containing 1-2% amelogenin were longer (3-5 times larger in aspect ratio) than the OCP crystals formed in 10% gelatin without amelogenin. A profound effect was that found in the cation selective Membrane system when 10% amelogenin inhibited the growth morphology in a specific manner. Affected crystals had a length to width ratio twice larger than that of control crystals while the width to thickness ratio was about 1/12 of that of the control crystals. Amelogenin promoted the formation of bundles of lengthwise apatite crystals, which were all oriented parallel to their c axes when grown on SCSrM179. It was found that individual apatite crystals within those bundles adopted an elongated, curved shape. The data presented here suggest that amelogenin nanospheres modulate the growth morphology of apatite and OCP crystals and indicate significant functional roles for amelogenin proteins during the in vivo oriented growth of enamel crystallites.