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

  • cathode flooding behaviour in alkaline direct ethanol fuel cells
    Journal of Power Sources, 2011
    Co-Authors: Tianshou Zhao, Rong Chen
    Abstract:

    In an alkaline fuel cell, such as a direct ethanol fuel cell (DEFC), owing to the fact that water is consumed as a reactant at the cathode and the electro-osmotic drag (EOD) moves water from the cathode to the anode, a conventional conception is that the cathode flooding is unlikely. In this work, however, it is shown experimentally that cathode flooding also occurs in an alkaline DEFC, primarily because of the fact that the Diffusion Flux from the anode to the cathode outweighs the total water Flux due to both the oxygen reduction reaction and EOD. More interestingly, rather than in acid electrolyte based fuel cells where the cathode flooding occurs at a high (limiting) current, in an alkaline DEFC the cathode flooding occurs at an intermediate current.

  • numerical investigations of effect of membrane electrode assembly structure on water crossover in a liquid feed direct methanol fuel cell
    Journal of Power Sources, 2009
    Co-Authors: Weiwei Yang, Tianshou Zhao
    Abstract:

    Abstract A two-phase mass-transport model is employed to investigate the water transport behaviour through the membrane electrode assembly (MEA) of a liquid-feed direct methanol fuel cell (DMFC). Emphasis is placed on examining the effects of each constituent component design of the MEA, including catalyst layers, microporous layers and membranes, on each of the three water crossover mechanisms: electro-osmotic drag, Diffusion, and convection. The results show that lowering the Diffusion Flux of water or enhancing the convection Flux of water (termed as the back-flow Flux) through the membrane are both feasible to suppress water crossover in DMFCs. It is found that the reduction in the Diffusion Flux of water can be mainly achieved through optimum design of the anode porous layers, as the effect of the cathode porous region on water crossover by Diffusion is relatively smaller. On the other hand, the design of the cathode porous layers plays a more important role in increasing the back-flow Flux of water from the cathode to anode.

  • numerical investigations of effect of membrane electrode assembly structure on water crossover in a liquid feed direct methanol fuel cell
    Journal of Power Sources, 2009
    Co-Authors: Weiwei Yang, Tianshou Zhao
    Abstract:

    Abstract A two-phase mass-transport model is employed to investigate the water transport behaviour through the membrane electrode assembly (MEA) of a liquid-feed direct methanol fuel cell (DMFC). Emphasis is placed on examining the effects of each constituent component design of the MEA, including catalyst layers, microporous layers and membranes, on each of the three water crossover mechanisms: electro-osmotic drag, Diffusion, and convection. The results show that lowering the Diffusion Flux of water or enhancing the convection Flux of water (termed as the back-flow Flux) through the membrane are both feasible to suppress water crossover in DMFCs. It is found that the reduction in the Diffusion Flux of water can be mainly achieved through optimum design of the anode porous layers, as the effect of the cathode porous region on water crossover by Diffusion is relatively smaller. On the other hand, the design of the cathode porous layers plays a more important role in increasing the back-flow Flux of water from the cathode to anode.

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

  • Diffusion of charged and uncharged contrast agents in equine mandibular condylar cartilage is not affected by an increased level of sugar induced collagen crosslinking
    Journal of The Mechanical Behavior of Biomedical Materials, 2019
    Co-Authors: Fereshteh Mirahmadi, J H Koolstra, S Fazaeli, Frank Lobbezoo, Harry G Van Lenthe, Jessica Snabel, Reinout Stoop, Vincent Everts
    Abstract:

    Nutrition of articular cartilage relies mainly on Diffusion and convection of solutes through the interstitial fluid due to the lack of blood vessels. The Diffusion is controlled by two factors: steric hindrance and electrostatic interactions between the solutes and the matrix components. Aging comes with changes in the cartilage structure and composition, which can influence the Diffusion. In this study, we treated fibrocartilage of mandibular condyle with ribose to induce an aging-like effect by accumulating collagen crosslinks. The effect of steric hindrance or electrostatic forces on the Diffusion was analyzed using either charged (Hexabrix) or uncharged (Visipaque) contrast agents. Osteochondral plugs from young equine mandibular condyles were treated with 500 mM ribose for 7 days. The effect of crosslinking on mechanical properties was then evaluated via dynamic indentation. Thereafter, the samples were exposed to contrast agents and imaged using contrast-enhanced computed tomography (CECT) at 18 different time points up to 48 h to measure their Diffusion. Normalized concentration of contrast agents in the cartilage and contrast agent Diffusion Flux, as well as the content of crosslink level (pentosidine), water, collagen, and glycosaminoglycan (GAG) were determined. Ribose treatment significantly increased the pentosidine level (from 0.01 to 7.6 mmol/mol collagen), which resulted in an increase in tissue stiffness (~1.5 fold). Interestingly, the normalized concentration and Diffusion Flux did not change after the induction of an increased level of pentosidine either for Hexabrix or Visipaque. The results of this study strongly suggest that sugar-induced collagen crosslinking in TMJ condylar cartilage does not affect the Diffusion properties.Nutrition of articular cartilage relies mainly on Diffusion and convection of solutes through the interstitial fluid due to the lack of blood vessels. The Diffusion is controlled by two factors: steric hindrance and electrostatic interactions between the solutes and the matrix components. Aging comes with changes in the cartilage structure and composition, which can influence the Diffusion. In this study, we treated fibrocartilage of mandibular condyle with ribose to induce an aging-like effect by accumulating collagen crosslinks. The effect of steric hindrance or electrostatic forces on the Diffusion was analyzed using either charged (Hexabrix) or uncharged (Visipaque) contrast agents. Osteochondral plugs from young equine mandibular condyles were treated with 500 mM ribose for 7 days. The effect of crosslinking on mechanical properties was then evaluated via dynamic indentation. Thereafter, the samples were exposed to contrast agents and imaged using contrast-enhanced computed tomography (CECT) at 18 different time points up to 48 h to measure their Diffusion. Normalized concentration of contrast agents in the cartilage and contrast agent Diffusion Flux, as well as the content of crosslink level (pentosidine), water, collagen, and glycosaminoglycan (GAG) were determined. Ribose treatment significantly increased the pentosidine level (from 0.01 to 7.6 mmol/mol collagen), which resulted in an increase in tissue stiffness (~1.5 fold). Interestingly, the normalized concentration and Diffusion Flux did not change after the induction of an increased level of pentosidine either for Hexabrix or Visipaque. The results of this study strongly suggest that sugar-induced collagen crosslinking in TMJ condylar cartilage does not affect the Diffusion properties.

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

  • numerical investigations of effect of membrane electrode assembly structure on water crossover in a liquid feed direct methanol fuel cell
    Journal of Power Sources, 2009
    Co-Authors: Weiwei Yang, Tianshou Zhao
    Abstract:

    Abstract A two-phase mass-transport model is employed to investigate the water transport behaviour through the membrane electrode assembly (MEA) of a liquid-feed direct methanol fuel cell (DMFC). Emphasis is placed on examining the effects of each constituent component design of the MEA, including catalyst layers, microporous layers and membranes, on each of the three water crossover mechanisms: electro-osmotic drag, Diffusion, and convection. The results show that lowering the Diffusion Flux of water or enhancing the convection Flux of water (termed as the back-flow Flux) through the membrane are both feasible to suppress water crossover in DMFCs. It is found that the reduction in the Diffusion Flux of water can be mainly achieved through optimum design of the anode porous layers, as the effect of the cathode porous region on water crossover by Diffusion is relatively smaller. On the other hand, the design of the cathode porous layers plays a more important role in increasing the back-flow Flux of water from the cathode to anode.

  • numerical investigations of effect of membrane electrode assembly structure on water crossover in a liquid feed direct methanol fuel cell
    Journal of Power Sources, 2009
    Co-Authors: Weiwei Yang, Tianshou Zhao
    Abstract:

    Abstract A two-phase mass-transport model is employed to investigate the water transport behaviour through the membrane electrode assembly (MEA) of a liquid-feed direct methanol fuel cell (DMFC). Emphasis is placed on examining the effects of each constituent component design of the MEA, including catalyst layers, microporous layers and membranes, on each of the three water crossover mechanisms: electro-osmotic drag, Diffusion, and convection. The results show that lowering the Diffusion Flux of water or enhancing the convection Flux of water (termed as the back-flow Flux) through the membrane are both feasible to suppress water crossover in DMFCs. It is found that the reduction in the Diffusion Flux of water can be mainly achieved through optimum design of the anode porous layers, as the effect of the cathode porous region on water crossover by Diffusion is relatively smaller. On the other hand, the design of the cathode porous layers plays a more important role in increasing the back-flow Flux of water from the cathode to anode.

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

  • Diffusion of charged and uncharged contrast agents in equine mandibular condylar cartilage is not affected by an increased level of sugar induced collagen crosslinking
    Journal of The Mechanical Behavior of Biomedical Materials, 2019
    Co-Authors: Fereshteh Mirahmadi, J H Koolstra, S Fazaeli, Frank Lobbezoo, Harry G Van Lenthe, Jessica Snabel, Reinout Stoop, Vincent Everts
    Abstract:

    Nutrition of articular cartilage relies mainly on Diffusion and convection of solutes through the interstitial fluid due to the lack of blood vessels. The Diffusion is controlled by two factors: steric hindrance and electrostatic interactions between the solutes and the matrix components. Aging comes with changes in the cartilage structure and composition, which can influence the Diffusion. In this study, we treated fibrocartilage of mandibular condyle with ribose to induce an aging-like effect by accumulating collagen crosslinks. The effect of steric hindrance or electrostatic forces on the Diffusion was analyzed using either charged (Hexabrix) or uncharged (Visipaque) contrast agents. Osteochondral plugs from young equine mandibular condyles were treated with 500 mM ribose for 7 days. The effect of crosslinking on mechanical properties was then evaluated via dynamic indentation. Thereafter, the samples were exposed to contrast agents and imaged using contrast-enhanced computed tomography (CECT) at 18 different time points up to 48 h to measure their Diffusion. Normalized concentration of contrast agents in the cartilage and contrast agent Diffusion Flux, as well as the content of crosslink level (pentosidine), water, collagen, and glycosaminoglycan (GAG) were determined. Ribose treatment significantly increased the pentosidine level (from 0.01 to 7.6 mmol/mol collagen), which resulted in an increase in tissue stiffness (~1.5 fold). Interestingly, the normalized concentration and Diffusion Flux did not change after the induction of an increased level of pentosidine either for Hexabrix or Visipaque. The results of this study strongly suggest that sugar-induced collagen crosslinking in TMJ condylar cartilage does not affect the Diffusion properties.Nutrition of articular cartilage relies mainly on Diffusion and convection of solutes through the interstitial fluid due to the lack of blood vessels. The Diffusion is controlled by two factors: steric hindrance and electrostatic interactions between the solutes and the matrix components. Aging comes with changes in the cartilage structure and composition, which can influence the Diffusion. In this study, we treated fibrocartilage of mandibular condyle with ribose to induce an aging-like effect by accumulating collagen crosslinks. The effect of steric hindrance or electrostatic forces on the Diffusion was analyzed using either charged (Hexabrix) or uncharged (Visipaque) contrast agents. Osteochondral plugs from young equine mandibular condyles were treated with 500 mM ribose for 7 days. The effect of crosslinking on mechanical properties was then evaluated via dynamic indentation. Thereafter, the samples were exposed to contrast agents and imaged using contrast-enhanced computed tomography (CECT) at 18 different time points up to 48 h to measure their Diffusion. Normalized concentration of contrast agents in the cartilage and contrast agent Diffusion Flux, as well as the content of crosslink level (pentosidine), water, collagen, and glycosaminoglycan (GAG) were determined. Ribose treatment significantly increased the pentosidine level (from 0.01 to 7.6 mmol/mol collagen), which resulted in an increase in tissue stiffness (~1.5 fold). Interestingly, the normalized concentration and Diffusion Flux did not change after the induction of an increased level of pentosidine either for Hexabrix or Visipaque. The results of this study strongly suggest that sugar-induced collagen crosslinking in TMJ condylar cartilage does not affect the Diffusion properties.

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

  • stages of steady Diffusion growth of a gas bubble in strongly supersaturated gas liquid solution
    Colloid Journal, 2009
    Co-Authors: A. E. Kuchma, Yu G Gor, F M Kuni
    Abstract:

    Gas bubble growth as a result of Diffusion Flux of dissolved gas molecules from the surrounding supersaturated solution to the bubble surface is studied. The condition of the Flux steadiness is revealed. A limitation from below on the bubble radius is considered. Its fulfillment guarantees the smallness of fluctuation influence on bubble growth and irreversibility of this process. Under the conditions of steadiness of Diffusion Flux three stages of bubble growth are marked out. Taking into account Laplace forces in the bubble, intervals of bubble size change and time intervals of these stages are found. The trend of the third stage towards the self-similar regime of the bubble growth, when Laplace forces in the bubble are completely neglected, is described analytically.

  • Gas bubble growth dynamics in a supersaturated solution: Henry's and Sievert's solubility laws
    arXiv: Chemical Physics, 2009
    Co-Authors: A. E. Kuchma, Gennady Y. Gor, F M Kuni
    Abstract:

    Theoretical description of Diffusion growth of a gas bubble after its nucleation in supersaturated liquid solution is p resented. We study the influence of Laplace pressure on the bubble growt h. We consider two different solubility laws: Henry’s law, whi ch is fulfilled for the systems where no gas molecules dissociat ion takes place and Sievert’s law, which is fulfilled for the syst ems where gas molecules completely dissociate in the solvent into two parts. We show that the difference between Henry’s and Sievert’s laws for chemical equilibrium conditions causes the difference in bubble growth dynamics. Assuming that Diffusion Flux of dissolved gas molecules to the bubble is steady we obtain differential equations on bubble radius for both solubility la ws. For the case of homogeneous nucleation of a bubble, which takes place at a significant pressure drop bubble dynamics equatio ns for Henry’s and Sievert’s laws are solved analytically. For both solubility laws three characteristic stages of bubble grow th are marked out. Intervals of bubble size change and time intervals of these stages are found. We also obtain conditions of Diffusion Flux steadiness corresponding to consecutive stages. The fu lfillment of these conditions is discussed for the case of nucleation of water vapor bubbles in magmatic melts. For Sievert’s law the analytical treatment of the problem of bubble dissolution in a pure solvent is also presented.

  • dynamics of gas bubble growth in a supersaturated solution with sievert s solubility law
    Journal of Chemical Physics, 2009
    Co-Authors: A. E. Kuchma
    Abstract:

    This paper presents a theoretical description of Diffusion growth of a gas bubble after its nucleation in supersaturated liquid solution. We study systems where gas molecules completely dissociate in the solvent into two parts, thus making Sievert’s solubility law valid. We show that the difference between Henry’s and Sievert’s laws for chemical equilibrium conditions causes the difference in bubble growth dynamics. Assuming that Diffusion Flux is steady we obtain a differential equation on bubble radius. Bubble dynamics equation is solved analytically for the case of homogeneous nucleation of a bubble, which takes place at a significant pressure drop. We also obtain conditions of Diffusion Flux steadiness. The fulfillment of these conditions is studied for the case of nucleation of water vapor bubbles in magmatic melts.