Palladium/Cobalt Coated on Multi‐Walled Carbon Nanotubes as an Electro‐catalyst for Oxygen Reduction Reaction in Passive Direct Methanol Fuel Cells

This work reports the synthesis of Pd‐based alloy electrocatalysts of Co supported on multi‐walled carbon nanotubes (MWCNTs) and their evaluation as cathode materials in a passive direct methanol fuel cell (PDMFC). The X‐ray diffraction (XRD) analysis showed well‐defined reflections corresponding to a face centered cubic phase of palladium. As compared to the Pd/MWCNT electrocatalyst, the bimetallic alloy electrocatalysts with the different Pd_xCo atomic ratios showed highly enhanced mass activity (MA) for the oxygen reduction reaction (ORR); however, the significant enhancement in the specific activity (SA) by a factor of about 1.2–5.6 for the ORR was found on the Pd_xCo alloy electrocatalysts in the presence and absence of methanol electrolyte solution. This enhancement SA in of the Pd‐based electrocatalysts was correlated to the changes in the lattice parameter and Pd_xCo surface composition. Surface area changes of Pd‐based electrocatalysts supported on MWCNT were evaluated using an accelerated durability test (ADT). The results obtained using the ADT were correlated to the performance of the Pd‐based electrocatalysts in the PDMFC. A better performance was obtained for the cell using Pd₃Co/MWCNT (2.53 mW cm^–2) compared to Pd/MWCNT (1.64 mW cm^–2) and Pt/C‐Electrochem (1.20 mW cm^–2) as cathode in the PDMFC. In the presence and absence of methanol the impedance Bode spectra showed one time constant that associated to follow a four electron pathway.     

Degradation Mechanism of Anode‐Supported Solid Oxide Fuel Cell In Planar‐Cell Channel‐Type Setup

The degradation mechanism of anode‐supported planar solid oxide fuel cells is investigated in the present work. We fabricate a large‐area (10 cm × 10 cm) cell and carry out a long‐term test with the assembly components. A constant current of ∼0.4 A cm^–2 is applied to the cell for ∼3,100 h, and the furnace temperature is controlled in the sequence 750–800–750 °C to investigate the effect of operating temperature and thermal cycling on the degradation rate. Impedance spectra and current–voltage characteristics are measured during the operation in order to trace any increase in Ohmic and non‐Ohmic resistance as a function of time. The degradation rate is rapid during the operation at the higher temperature of ∼800 °C compared to that during the operation at ∼750 °C. Even after cooling down to ∼750 °C, that rate is still accelerated. The main contribution to the cell degradation is from an increase in the Ohmic resistance. Postmaterial analyses indicate that the cathode is delaminated at the electrolyte/cathode interface, which is attributed to the difference in thermal expansion coefficient (TEC). Thus, the present results emphasize the importance of matching the TEC between cell layers, especially under severe operating conditions such as long duration and complex thermal cycling.     

话音优先策略在翘尾效应中的应用

为解决GSM最差小区话音拥塞和掉话的翘尾效应,提出在突发话务量的情况下,通过限制数据业务静态信道的比例,采取适当允许话音业务优先抢占动态分组数据信道（PDCH）的话音优先策略.此策略最大可能满足话音业务信道需求,缓解突发性话音拥塞和掉话现象.经省内外多城市试点测试,优化效果明显,具有一定的工程实用价值.     

太阳能光伏声屏障

除了光伏与建筑一体化以外,另一个不需占用土地,兼具两种功能的光伏应用领域是光伏声屏障。本文介绍了光伏声屏障的应用及其存在的问题,提出了用非晶硅太阳电池组件作为声屏障的设想。指出作为蓬勃发展的光伏发电与潜力巨大的声屏障两者结合点的光伏声屏障,具有十分广阔的发展前景。     

Impact of Compression on Effective Thermal Conductivity and Diffusion Coefficient of Woven Gas Diffusion Layers in Polymer Electrolyte Fuel Cells

The contrasting effect of compression on the ability of gas diffusion layer (GDL) in polymer electrolyte membrane fuel cell to conduct fluid, heat and electron implies that there is an optimal clamping force for cell performance. For a given GDL, understanding its associated optimal compression needs to know how its conductive ability changes with compressive pressure. In this paper we investigated the impact of compression on the effective diffusion coefficient and thermal conductivity of a carbon‐cloth GDL. The interior microstructures of the GDL under different compressions were acquired using X‐ray tomography; microscopic models were then developed to simulate gas diffusion and heat transfer in the microstructures in both in‐plane and through‐plane directions. The effective diffusion coefficient and thermal conductivity were calculated by volumetrically averaging the simulated gas diffusive and thermal flux rates at micron scale. The results show that both effective diffusion coefficient and thermal conductivity were anisotropic and their values in the in‐plane direction were higher than in the through‐plane direction. With porosity decreasing under the compression, the effective diffusion coefficient decreased faster in the through‐plane direction than in the in‐plane direction; the formula derived by Nam and Kaviany was capable of describing the change of the effective diffusion coefficient with porosity in the in‐plane direction but not in the through‐plane direction. For heat transfer, as the porosity decreased, the thermal conductivity increased faster in the through‐plane direction than in the in‐plane direction, and the increase in both directions could fit to the formula of Das et al.     

商陆色素敏化TiO_2薄膜太阳能电池的初步研究

本文从商陆科植物商陆（Phytolacca acinosa Roxb）浆果中提取一种紫红水溶性色素,进行了敏化TiO2电极制备太阳能电池实验。结果表明：在紫外线强度134×100uw/cm2的模拟太阳光照射下,所制成的染料敏化电池可以产生0.13V的开路电压和0.007mA的短路电流;在紫外线强度90×100uw/cm...     

Cell behaviour on a polyaniline nanoprotrusion structure surface

The extracellular matrix provides mechanical support and affects cell behaviour. Nanoscale structures have been shown to have functions similar to the extracellular matrix. In this study, we fabricated nanoprotrusion structures with polyaniline as cell culture plates using a simple method and determined the effects of these nanoprotrusion structures on cells.     

A critical review on the cellular and molecular interactions at the interface of zirconia-based biomaterials

In the past few years, zirconia has gained a great attention among biomedical scientists due to its extraordinary strength and fracture toughness, negligible thermal conductivity, good biocompatibility and chemical inertness. In this regard, there is still room for the manipulation of zirconia-based biomaterials regarding the protein adsorption and subsequently cell responses to the surface. Protein adsorption on biomaterials surfaces start interpreting the construction and also arranging the surface characteristics into a biological language. In this review, the role of adsorbed proteins as key players in starting interactions between cells and zirconia-based biomaterials will be discussed in detail. The discussion will then highlight discussions on the implementation of innovative strategies to engineer the physiochemical properties of this class of biomaterials. It is expected that these promising solutions can better control proteins adsorption and cellular functions after implantation in the body.     

Femtosecond laser multi-patterning of zirconia for screening of cell-surface interactions

Yttria-stabilised tetragonal zirconia polycrystals (3Y-TZP) bioinert ceramics combine excellent strength and toughness, good aesthetics, high resistance to corrosion and absence of allergic reaction. However, improved osseointegration is needed as higher marginal bone loss was sometimes reported. In the present work, 3Y-TZP multi-patterned samples for rapid screening of cell-surface interactions were fabricated by femtosecond laser micromachining. Pits with well-defined edges and micrometric precision in pit diameter, depth and spacing were produced, as determined by white light interferometry. Pits showed a nanometric granular texture on the sidewalls and ripples at pit bottom, as attested by scanning electron microscopy. Focused ion beam analyses indicated limited laser-induced damage. Micropatterns impacted human mesenchymal stem cell (hMSC) size and morphology. Cell area and aspect ratio were mainly influenced by pit diameter, while solidity and circularity were affected by both pit diameter and depth. The pattern 30 μm diameter/10 μm depth induced the strongest osteoblastic hMSC commitment.     

PHOTOVOLTAIC CELLS AND MODULES: TECHNICAL AND ECONOMIC OUTLOOK TOWARDS THE YEAR 2000

There is a clear need for renewable energy and PV is a very attractive renewable energy source. The paper describes the different requirements for photovoltaic materials and compares these materials on the basis of these requirements. Silicon in general and crystalline silicon in particular fullfil the largest part of the current PV-market and the technological issues of this materials are therefore described in more detail from source(feedstock) material, over crystallization and wafering up to cell and module fabrication. The potentiality to serve the market and the ecological impact are extremely large and encouraging. Industrial capacity is increasing. Some applications are economic already now at current prices, but the large electrical market penetration can only come if conversion efficiencies are increased and cost is reduced further by accelerating the increase in production volumes and R&D efforts considerably.