The Experts below are selected from a list of 216 Experts worldwide ranked by ideXlab platform

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

  • Chitosan membranes filled by GPTMS-modified zeolite Beta Particles with low methanol permeability for DMFC
    Chemical Engineering and Processing: Process Intensification, 2010
    Co-Authors: Yabo Wang, Zhongyi Jiang, Dong Yang
    Abstract:

    Abstract Uniform zeolite Beta Particles about 800 nm in diameter were synthesized by a hydrothermal method, and functionalized by γ-glycidoxypropyltrimethoxysilane (GPTMS). Subsequently, chitosan (CS) membranes filled by GPTMS-modified zeolite Beta Particles were prepared, and characterized by SEM, FT-IR, XRD and TGA. Compared with the pure CS and Nafion®117 membrane, these CS/zeolite Beta hybrid membranes show apparently the lower methanol permeability, which could be assigned to the better interfacial morphology and compatibility between the GPTMS-modified zeolite Beta Particles and chitosan matrix. In all the prepared CS/zeolite Beta hybrid membranes, the CS membrane filled by 10 wt.% GPTMS-modified zeolite Beta Particles exhibits the lowest methanol permeability, which is 4.4 × 10−7 and 2.2 × 10−7 cm2 s−1 at 2 and 12 M methanol concentration, respectively. The proton conductivity of this hybrid membrane is 1.31 × 10−2 S cm−1, which is slightly lower than that of the pure CS membrane. The selectivity of CS/GPTMS-zeolite Beta membranes is comparable with Nafion® 117 at 2 M methanol concentration, and much higher at 12 M methanol concentration.

  • zeolite Beta filled chitosan membrane with low methanol permeability for direct methanol fuel cell
    Journal of Power Sources, 2008
    Co-Authors: Yabo Wang, Dong Yang, Xiaohong Zheng, Zhongyi Jiang
    Abstract:

    Abstract Zeolite Beta Particles with different sizes and narrow size distribution were hydrothermally synthesized and incorporated into chitosan (CS) matrix to prepare CS/zeolite Beta hybrid membranes for direct methanol fuel cell (DMFC). It was found that the chitosan membrane filled by zeolite Beta Particles about 800 nm in size exhibited the lowest methanol permeability, which can be ascribed to their optimum free volume and methanol diffusion characteristics. To further improve the performances of CS/zeolite Beta hybrid membranes, zeolite Beta Particles about 800 nm in size were sulfonated via three different approaches. The results indicated that the introduction of sulfonic groups could reduce the methanol permeability further as a result of the enhanced interfacial interaction between zeolite Beta and chitosan matrix. Furthermore, in terms of the overall selectivity index, CS/zeolite Beta hybrid membranes were comparable to Nafion ® 117 membrane at low methanol concentration (2 mol L −1 ) and much better at high methanol concentration (12 mol L −1 ).

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

  • Chitosan membranes filled by GPTMS-modified zeolite Beta Particles with low methanol permeability for DMFC
    Chemical Engineering and Processing: Process Intensification, 2010
    Co-Authors: Yabo Wang, Zhongyi Jiang, Dong Yang
    Abstract:

    Abstract Uniform zeolite Beta Particles about 800 nm in diameter were synthesized by a hydrothermal method, and functionalized by γ-glycidoxypropyltrimethoxysilane (GPTMS). Subsequently, chitosan (CS) membranes filled by GPTMS-modified zeolite Beta Particles were prepared, and characterized by SEM, FT-IR, XRD and TGA. Compared with the pure CS and Nafion®117 membrane, these CS/zeolite Beta hybrid membranes show apparently the lower methanol permeability, which could be assigned to the better interfacial morphology and compatibility between the GPTMS-modified zeolite Beta Particles and chitosan matrix. In all the prepared CS/zeolite Beta hybrid membranes, the CS membrane filled by 10 wt.% GPTMS-modified zeolite Beta Particles exhibits the lowest methanol permeability, which is 4.4 × 10−7 and 2.2 × 10−7 cm2 s−1 at 2 and 12 M methanol concentration, respectively. The proton conductivity of this hybrid membrane is 1.31 × 10−2 S cm−1, which is slightly lower than that of the pure CS membrane. The selectivity of CS/GPTMS-zeolite Beta membranes is comparable with Nafion® 117 at 2 M methanol concentration, and much higher at 12 M methanol concentration.

  • zeolite Beta filled chitosan membrane with low methanol permeability for direct methanol fuel cell
    Journal of Power Sources, 2008
    Co-Authors: Yabo Wang, Dong Yang, Xiaohong Zheng, Zhongyi Jiang
    Abstract:

    Abstract Zeolite Beta Particles with different sizes and narrow size distribution were hydrothermally synthesized and incorporated into chitosan (CS) matrix to prepare CS/zeolite Beta hybrid membranes for direct methanol fuel cell (DMFC). It was found that the chitosan membrane filled by zeolite Beta Particles about 800 nm in size exhibited the lowest methanol permeability, which can be ascribed to their optimum free volume and methanol diffusion characteristics. To further improve the performances of CS/zeolite Beta hybrid membranes, zeolite Beta Particles about 800 nm in size were sulfonated via three different approaches. The results indicated that the introduction of sulfonic groups could reduce the methanol permeability further as a result of the enhanced interfacial interaction between zeolite Beta and chitosan matrix. Furthermore, in terms of the overall selectivity index, CS/zeolite Beta hybrid membranes were comparable to Nafion ® 117 membrane at low methanol concentration (2 mol L −1 ) and much better at high methanol concentration (12 mol L −1 ).

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

  • Chitosan membranes filled by GPTMS-modified zeolite Beta Particles with low methanol permeability for DMFC
    Chemical Engineering and Processing: Process Intensification, 2010
    Co-Authors: Yabo Wang, Zhongyi Jiang, Dong Yang
    Abstract:

    Abstract Uniform zeolite Beta Particles about 800 nm in diameter were synthesized by a hydrothermal method, and functionalized by γ-glycidoxypropyltrimethoxysilane (GPTMS). Subsequently, chitosan (CS) membranes filled by GPTMS-modified zeolite Beta Particles were prepared, and characterized by SEM, FT-IR, XRD and TGA. Compared with the pure CS and Nafion®117 membrane, these CS/zeolite Beta hybrid membranes show apparently the lower methanol permeability, which could be assigned to the better interfacial morphology and compatibility between the GPTMS-modified zeolite Beta Particles and chitosan matrix. In all the prepared CS/zeolite Beta hybrid membranes, the CS membrane filled by 10 wt.% GPTMS-modified zeolite Beta Particles exhibits the lowest methanol permeability, which is 4.4 × 10−7 and 2.2 × 10−7 cm2 s−1 at 2 and 12 M methanol concentration, respectively. The proton conductivity of this hybrid membrane is 1.31 × 10−2 S cm−1, which is slightly lower than that of the pure CS membrane. The selectivity of CS/GPTMS-zeolite Beta membranes is comparable with Nafion® 117 at 2 M methanol concentration, and much higher at 12 M methanol concentration.

  • zeolite Beta filled chitosan membrane with low methanol permeability for direct methanol fuel cell
    Journal of Power Sources, 2008
    Co-Authors: Yabo Wang, Dong Yang, Xiaohong Zheng, Zhongyi Jiang
    Abstract:

    Abstract Zeolite Beta Particles with different sizes and narrow size distribution were hydrothermally synthesized and incorporated into chitosan (CS) matrix to prepare CS/zeolite Beta hybrid membranes for direct methanol fuel cell (DMFC). It was found that the chitosan membrane filled by zeolite Beta Particles about 800 nm in size exhibited the lowest methanol permeability, which can be ascribed to their optimum free volume and methanol diffusion characteristics. To further improve the performances of CS/zeolite Beta hybrid membranes, zeolite Beta Particles about 800 nm in size were sulfonated via three different approaches. The results indicated that the introduction of sulfonic groups could reduce the methanol permeability further as a result of the enhanced interfacial interaction between zeolite Beta and chitosan matrix. Furthermore, in terms of the overall selectivity index, CS/zeolite Beta hybrid membranes were comparable to Nafion ® 117 membrane at low methanol concentration (2 mol L −1 ) and much better at high methanol concentration (12 mol L −1 ).

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

  • thermoluminescent response of zro2 ptfe prepared in mexico to 90sr 90y Beta Particles
    Radiation Protection Dosimetry, 2002
    Co-Authors: T Rivera, J Azorín, G Falcony, M García, E Martínez
    Abstract:

    Results of studying the thermoluminescent response of undoped ZrO2 + PTFE pellets irradiated with 90Sr/90Y Beta Particles are presented. Previously, TL characteristics of ZrO2 films doped with rare earths were studied. Phosphor powder was obtained by evaporating a solution of zirconium nitrate in ethanol. In order to stabilise the traps in ZrO2 this phosphor was submitted to different thermal treatments. Optimal thermal treatment consisted in heating at 1100 degrees C for 24 h. With this powder. pressing at room temperature a mixture (2:1) of ZrO2 and polytetrafluoroethylene (PTFE), pellets of 5 mm diameter and 0.8 mm thickness were made. The glow curve of ZrO2 + PTFE pellets exhibited two peaks at 200 and 250 degrees C: its TL response as a function of Beta Particles dose was linear in the range from 2 to 60 Gy. Repeatability over 10 cycles was 1.8%. Fading at room temperature was 3.8% per month.

  • Thermoluminescent response of ZrO2+PTFE prepared in Mexico to 90Sr/90Y Beta Particles
    Radiation Protection Dosimetry, 2002
    Co-Authors: T Rivera, J Azorín, G Falcony, M García, E Martínez
    Abstract:

    Results of studying the thermoluminescent response of undoped ZrO2 + PTFE pellets irradiated with 90Sr/90Y Beta Particles are presented. Previously, TL characteristics of ZrO2 films doped with rare earths were studied. Phosphor powder was obtained by evaporating a solution of zirconium nitrate in ethanol. In order to stabilise the traps in ZrO2 this phosphor was submitted to different thermal treatments. Optimal thermal treatment consisted in heating at 1100 degrees C for 24 h. With this powder. pressing at room temperature a mixture (2:1) of ZrO2 and polytetrafluoroethylene (PTFE), pellets of 5 mm diameter and 0.8 mm thickness were made. The glow curve of ZrO2 + PTFE pellets exhibited two peaks at 200 and 250 degrees C: its TL response as a function of Beta Particles dose was linear in the range from 2 to 60 Gy. Repeatability over 10 cycles was 1.8%. Fading at room temperature was 3.8% per month.

  • Thermoluminescent response of ZrO2 + PTFE prepared in Mexico to 90Sr/90Y Beta Particles.
    Radiation Protection Dosimetry, 2002
    Co-Authors: T Rivera, J Azorín, M García, C. Falcony, E Martínez
    Abstract:

    Results of studying the thermoluminescent response of undoped ZrO 2 + PTFE pellets irradiated with 90 Sr/ 90 Y Beta Particles are presented. Previously, TL characteristics of ZrO 2 films doped with rare earths were studied. Phosphor powder was obtained by evaporating a solution of zirconium nitrate in ethanol. In order to stabilise the traps in ZrO 2 this phosphor was submitted to different thermal treatments. Optimal thermal treatment consisted in heating at 1100°C for 24 h. With this powder, pressing at room temperature a mixture (2:1) of ZrO 2 and polytetrafluoroethylene (PTFE), pellets of 5 mm diameter and 0.8 mm thickness were made. The glow curve of ZrO 2 + PTFE pellets exhibited two peaks at 200 and 250°C; its TL response as a function of Beta Particles dose was linear in the range from 2 to 60 Gy. Repeatability over 10 cycles was 1.8%. Fading at room temperature was 3.8% per month.

  • Thermoluminescent response of ZrO2 + PTFE prepared in Mexico to 90Sr/90Y Beta Particles.
    Radiation protection dosimetry, 2002
    Co-Authors: T Rivera, J Azorín, G Falcony, M García, E Martínez
    Abstract:

    Results of studying the thermoluminescent response of undoped ZrO2 + PTFE pellets irradiated with 90Sr/90Y Beta Particles are presented. Previously, TL characteristics of ZrO2 films doped with rare earths were studied. Phosphor powder was obtained by evaporating a solution of zirconium nitrate in ethanol. In order to stabilise the traps in ZrO2 this phosphor was submitted to different thermal treatments. Optimal thermal treatment consisted in heating at 1100 degrees C for 24 h. With this powder. pressing at room temperature a mixture (2:1) of ZrO2 and polytetrafluoroethylene (PTFE), pellets of 5 mm diameter and 0.8 mm thickness were made. The glow curve of ZrO2 + PTFE pellets exhibited two peaks at 200 and 250 degrees C: its TL response as a function of Beta Particles dose was linear in the range from 2 to 60 Gy. Repeatability over 10 cycles was 1.8%. Fading at room temperature was 3.8% per month.

Robert G. Gilbert - One of the best experts on this subject based on the ideXlab platform.

  • Nature of alpha and Beta Particles in glycogen using molecular size distributions.
    Biomacromolecules, 2010
    Co-Authors: Mitchell A. Sullivan, Francisco Vilaplana, Richard A. Cave, David Stapleton, Angus Gray-weale, Robert G. Gilbert
    Abstract:

    Glycogen is a randomly hyperbranched glucose polymer. Complex branched polymers have two structural levels: individual branches and the way these branches are linked. Liver glycogen has a third level: supramolecular clusters of Beta Particles which form larger clusters of alpha Particles. Size distributions of native glycogen were characterized using size exclusion chromatography (SEC) to find the number and weight distributions and the size dependences of the number- and weight-average masses. These were fitted to two distinct randomly joined reference structures, constructed by random attachment of individual branches and as random aggregates of Beta Particles. The z-average size of the alpha Particles in dimethylsulfoxide does not change significantly with high concentrations of LiBr, a solvent system that would disrupt hydrogen bonding. These data reveal that the Beta Particles are covalently bonded to form alpha Particles through a hitherto unsuspected enzyme process, operative in the liver on Particles above a certain size range.