[en] The internal transport mechanisms, which were acquired from the modeling results in Part I of this series, are discussed and compared for PEM fuel cells with a conventional flow field and an interdigitated flow field. The modeling results show that the oxygen concentration fraction in an interdigitated flow field is higher than that in a conventional flow field to increase the reaction rate, and the liquid water saturation in the former flow field is much less than that in the latter one at the cathode side to reduce the concentration overpotential largely. However, if the cathode inlet air in a PEM fuel cell with interdigitated flow field is not humidified, the performance of this fuel cell is inferior to that of a PEM fuel cell with conventional flow field because of a larger ohmic overpotential. As a result, the humidification is important for an interdigitated flow field to acquire a much better performance than a conventional flow field

[en] A full three dimensional PEM fuel cell model is developed, which considers not only the rib resistance to the species but both the single and two phase flow and transport in the gas channels and diffusers at both the anode and cathode sides of the PEM fuel cell. Two sets of boundary conditions, one for a conventional flow field and the other for an interdigitated one, are presented. A detailed discussion of the numerical techniques for the PEM fuel cell model is given with a flow diagram to provide an overview of the solution procedure using the FORTRAN language. A rigorous validation method is used to show good agreement between our predicted results and the experimental data

[en] Objective: To investigate the relationship between changes of serum leptin levels and glomerulosclerosis index, TGF-β₁ expression at glomerulus as well as degree of ECM proliferation in rats after 5/6 nephrectomy. Methods: Eight rats underwent two-stage 5/6 nephrectomy to establish a progressive glomeruloselerosis model. Six weeks after the second operation, the rats were sacrificed, the renal tissue was examined with routine pathological sections for study of glomerulosclerosis as well as with immunohistochemical studies for TGF-β₁, collagen IV and fibronectin expressions. Six rats underwent sham operation served as controls. Serum creatinine, urea nitrogen and leptin levels were measured in all these animals. Results: The serum levels of leptin were significantly higher in rats after 5/6 nephrectomy than the rats with sham operations (14.88 ± 1.46ng/ml vs 10.84 ± 2.67ng/ml, P < 0. 01 ). Serum levels of leptin were positively correlated with the glomeruloselerosis index and collagen IV, fibronectin expressions ( P < 0.01 ). Conclusion: Hyperleptinemia may be one of the causative factors of development of glomerulosclerosis. (authors)

[en] The proton exchange membrane fuel cell (PEMFC) is one of the most important power supplies. The operating temperature of the stack is an important controlled variable, which impacts the performance of the PEMFC. In order to improve the generating performance of the PEMFC, prolong its life and guarantee safety, credibility and low cost of the PEMFC system, it must be controlled efficiently. A nonlinear predictive control algorithm based on a least squares support vector machine (LS-SVM) model is presented for a family of complex systems with severe nonlinearity, such as the PEMFC, in this paper. The nonlinear off line model of the PEMFC is built by a LS-SVM model with radial basis function (RBF) kernel so as to implement nonlinear predictive control of the plant. During PEMFC operation, the off line model is linearized at each sampling instant, and the generalized predictive control (GPC) algorithm is applied to the predictive control of the plant. Experimental results demonstrate the effectiveness and advantages of this approach

[en] The microstructure and electrochemical performance of Ti_0.17Zr_0.08V_0.34Pd_0.01Cr_0.1Ni_0.3 electrode alloy have been investigated using X-ray diffraction, field emission scanning electron microscopy-energy dispersive spectroscopy, inductively coupled plasma and electrochemical impedance spectroscopy. The alloy electrode has a higher discharge capacity than an AB₅ type alloy within a wider temperature span. The increase of the charge-transfer-resistances, and the dissolutions of V and Zr were responsible for the performance degradation of the alloy electrode