Simulation and design of cathode catalyst layer in proton exchange membrane fuel cells

燃料电池是一种高效、清洁的能源利用方式，但要依赖于价格昂贵的Pt基贵金属催化剂。为了降低燃料电池成本，非贵金属催化剂Fe/N/C材料受到了广泛关注。但Fe/N/C催化剂制备的阴极催化层厚度较大，比传统铂催化层厚度大1个数量级，使得阴极传质过程变得更加困难。燃料电池Fe/N/C阴极催化层的传质成为其应用的一个难题。燃料电池结构和过程复杂，原位表征、在线表征手段比较缺乏，人们难以准确得到燃料电池中物质的传递数据。利用成熟的理论基础，建立合理的燃料电池数学模型，可以获取电池运行中的微观数据，使得仿真模拟在燃料电池研究中扮演着越来越重的角色。 在本论文中，我建立了燃料电池阴极催化层模型，模型求解区域...Fuel cell is an electrochemcial energy conversion device with high efficiency and low emissions. However, its large-scale commercialization is limited by high cost, which mainly comes from expensive Pt-based precious metal catalysts. In order to reduce the cost of fuel cell, Fe/N/C non-noble metal catalyst has received wide attention. However, the high thickness the cathode catalyst layer made by ...学位：理学硕士院系专业：化学化工学院_物理化学学号：2052014115161

St8sia1-deficiency in mice alters tumor environments of gliomas, leading to reduced disease severity

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The Construction of a Vector for Endosperm-specific Expression of IPT Gene and It's Transformation in Rice

为研究细胞分裂素在水稻籽粒发育中的作用,构建了P1300-P Pg-5α-IPT-nOS植物表达载体,并对水稻进行遗传转化。以水稻品种9311为材料,采用PCr法获得种子中特异表达的Pg-5α基因启动子,并将此启动子与P1300相连接,构建P1300-P Pg-5α载体,用nCOⅠ和SPEⅠ双酶切P Sg516,获得IPT-nOS核酸片段,然后将此核酸片段插入到P1300-P Pg-5α中,构建P1300-P Pg-5α-IPT-nOS植物表达载体。以水稻品种日本晴愈伤组织为材料,采用农杆菌介导的方法进行遗传转化。成功构建了植物表达载体P1300-P Pg-5α-IPT-nOS,获得了阳性率为81.3%转IPT基因群体。获得转基因株系后,将为进一步筛选高效表达株系及观察其籽粒生长发育过程提供基础。In order to specifically express IPT gene in the endosperm of developing rice seed,the binary vector p1300-p PG-5α-IPT-Nos was constructed,firstly,the promoter of PG-5α was obtained by PCR amplification from rice genomic DNA( variety: 9311) and p1300-p PG-5α was constructed by inserting p PG-5α into p1300,then the IPT-Nos fragment was obtained by cutting p SG516 with Nco Ⅰ and Spe Ⅰ.After IPT-Nos inserted into p1300-p PG-5α,p1300-p PG-5α-IPT-Nos was constructed.p PG-5α-IPT-Nos was transformated into Oryza sativa( subsp.japonicacv.Nipponbare) cells by agrobacterium mediated method and regenerative seedlings were obtained.The results of PCR showed that about 81.3% seedlings were positive.唐山师范学院博士基金项目(09A01); 农业部“948”项目(2011-G1(3)-07); 河北省科技计划项目(13396401D

Experimental Investigation on Thermocapillary Drop Migration at Large Marangoni Number in Reduced Gravity

Results from a space experiment on thermocapillary drop migration conducted on board the Chinese spacecraft ShenZhou-4 are presented in this paper. In the experiment, isolated drops of Fluorinert liquid moved in a matrix liquid of 5cst silicone oil at values of the Marangoni numbers (Ma) ranging up to 5500 and the interferometry images showed the temperature distribution inside the test cell. The drop migration velocity was measured. The experimental results show that the scaled drop migration velocity V/VYGB obviously decreases with Ma increasing the values up to 5500. The space experimental results are also compared with those from our early experiments, other space experiments, and some theoretical predictions

拘留所建筑单体实例

拟建拘留所建设工程包括以下建设内容：办公区、拘留区、连廊及室外配套工程。按照统一规划,有效利用资源,全盘考虑,建设一个设施完备,高效、便捷的工作场所。</jats:p

A Variant of Hormander's Condition and Weighted Estimates for Singular Integrals

设10和C_r>0,使对任意的y∈r~n和r>C_r|y|,有SuM((2kr)~(n/r')(InTEgrAl(︱k(X-y)-SuM(bJ(X)φJ(y)) frOM J=1 TO ∞︱_(dX)~r) frOM n=2krj(j = 1,...,m) are suitable functions.We say a kernel K satisfies a variant of the classical L~r-Hrmander's condition,if there exist constants c_r>0 and C_r>0,such that for any y∈R~n and R>c_r|y|, sum((2kR)~(n/r')(integral(︱K(x-y)-sum(Bj(x)φj(y)) from j=1 to ∞︱_(dx)~r) from n=2kR<︱x︱≤2(k+1)R))≤C_r In this paper,the authors establish the weighted norm inequalities for singular integral operators with kernel satisfying the above variant of the classical L~r-Hrmander's condition.国家自然科学基金资助项目(11041004); 黑龙江省自然科学基金项目(A200913