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The micro-porous polymer electrolytes membranes(PEMs), notably electro-spun fiber mats, have been suggested to give an improved ionic conductivity. However, the mat-type PEMs have a poor mechanical and dimensional stability because of their inevitable porous nature. In this study, we suggest a new PEM system based on poly(vinylidene fluoride)(PVdF) mats, which can overwhelm such shortcomings of the porous mats by introducing another component, poly(4-vinyl pyridine)(P4VP), into the mats. The tensile strength of PVdF/P4VP membrane was considerably improved compared with that of pristine PVdF membrane under dry and wet conditions. The ionic conductivity was also improved by about 10 times than that of PVdF mat. A micro- to nano-size gap was formed at the interfaces between PVdF nanofiber and P4VP, and this may act as a channel for fast ion transportation under wet condition.

Three different types of current-collecting plates for air-hydrogen PEM fuel cell were manufactured and tested: unmodified titanium plates; gold-plated titanium plates and titanium plates treated by carbon ions implantation. It was shown that the applied surface modifications reduce contact resistance between titanium plate and carbon gas diffusion layer. Total ohmic resistance of fuel cell is reduced by 1.8 and 1.4 times in case of gold-plated titanium and carbon-implanted titanium, respectively, in comparison with uncoated titanium. Although gold plating turned out to be more profitable than carbon ion implantation in terms of electrical characteristics, in the last case, the performance enhancement was reached without using precious metals, which at mass production must play more important role. This technology promises to reduce the cost of bipolar plates manufacturing, while maintaining high electrical performance of PEM fuel cells.

Replication of time series in microarray experiments is costly. To analyze time series data with no replicate, many model-specific approaches have been proposed. However, they fail to identify the genes whose expression patterns do not fit the pre-defined models. Besides, modeling the temporal expression patterns is difficult when the dynamics of gene expression in the experiment is poorly understood. We propose a method called Partial Energy ratio for Microarray (PEM) for the analysis of time course microarray data. In the PEM method, we assume the gene expressions vary smoothly in the temporal domain. This assumption is comparatively weak and hence the method is general enough to identify genes expressed in unexpected patterns. To identify the differentially expressed genes, a new statistic is developed by comparing the energies of two convoluted profiles. We further improve the statistic for microarray analysis by introducing the concept of partial energy. The PEM statistic can be easily incorporated into the SAM framework for significance analysis. We evaluated the PEM method with an artificial dataset and two published time course cDNA microarray datasets on yeast. The experimental results show the robustness and the generality of the PEM method in identifying the genes of interest.

Sulfonated poly(arylene ether sulfone) (SPAES) copolymer with degree of sulfonation of 1.0 was synthesized and characterized. A series of SPAES-TiO₂ hybrid membranes with various contents of nano-sized TiO₂ particles were prepared and characterized through sol-gel reactions. Scanning electron microscopy (SEM) images indicated the TiO₂ particles were well dispersed within polymer matrix. These composite membranes were evaluated for proton exchange membranes (PEMs) in direct methanol fuel cell (DMFC). These membranes showed good thermal stability and mechanical properties. It was found that the water uptake of these membranes increased with the increase of the TiO₂ contents in the hybrid membranes. Meanwhile, the introduction of inorganic particles increased the proton conductivity and reduced the methanol permeability. The proton conductivities (0.118–0.162 S/cm) of SPAES-TiO₂ hybrid membranes with 8% TiO₂ particles are much higher than those of Nafion 117 membrane (0.095–0.117 S/cm) and pure SPAES membrane (0.100–0.124 S/cm) with degree of sulfonation of 1.0 at all temperatures (25–100°C). Especially, the methanol diffusion coefficient (8.4 × 10^–7cm²/s) of SPAES-TiO₂ hybrid membranes with 8% TiO₂ is much lower than that of Nafion 117 membrane (2.1 × 10^–6cm²/s). SPAES-TiO₂ hybrid membranes were therefore proposed as candidates of material for PEM in DMFC.