Polyaniline/Platinum Composite Cathode Catalysts Towards Durable Polymer Electrolyte Membrane Fuel Cells

Polymer stabilization proved to be a promising approach to increase the catalytic performance of common platinum/carbon based cathode catalysts (Pt/C) used in polymer electrolyte membrane fuel cells (PEMFCs). Platinum and polyaniline composite catalysts (Pt/C/PANI) were prepared by combining chemical polymerization reactions with anion exchange reactions. Electrochemical ex-situ characterizations of the decorated Pt/C/PANI catalysts show high catalytic activity toward the oxygen reduction reaction (ORR) and, more importantly, a significant enhanced durability compared to the undecorated Pt/C catalyst. Transmission electron microscopy (TEM) investigations reveal structural benefits of Pt/C/PANI for ORR catalysis. All studies confirm high potential of Pt/C/PANI for practical fuel cell application.     

1-苯基-2-丙酮的合成新方法

以苯胺为原料,经重氮化反应和改进的Meerwein芳基化反应合成了1-苯基-2-丙酮(2)。优化的Meer-wein芳基化反应条件为:醋酸异丙烯酯为溶剂,氧化亚铜为催化剂,n(氟硼酸重氮盐)∶n(氧化亚铜)=10∶1,反应温度35℃~40℃,反应时间6 h。在优化反应条件下,2的收率达91%。     

一种优化设计的动目标检测方法及其运用

提出一种新的动目标检测(MTD)滤波器组设计方法,即通过设置目标处理通道和气象处理通道,其中目标通道采用自适应动目标检测(AMTD)处理方式,实时检测杂波的存在,根据杂波的强弱自动产生或选择滤波器加权因子,以保证对地杂波抑制的同时,减少信噪比损失,提高对弱小目标的检测性能.通过仿真结果,证明该方法是有效的,在工程上有一定的实用价值.     

Na-K liquid alloy:A review on wettability enhancement and ionic carrier selection mechanism

The intrinsic liquid interface of Na-K alloy allays concerns about dendrite growth on metal anodes that are thermodynamically within the room temperature(20-22℃).Nevertheless,it hinders the formation of a stable electrode structure due to the inferior wettability induced by considerable liquid tension.In addition,the dominant ionic carrier in the Na-K alloy is subject to multiple factors,which is not conducive to customized battery design.This review,based on recently reported frontier achievements on Na-K liquid anodes,summarizes practical strategies for promoting the wettability by hightemperature induction,capillary effect,vacuum infiltration,and solid interface protection.Furthermo re,four selection mechanisms of the dominant ionic carrier are presented:(1) ion property dominated,(2)cathode dominated,(3) separator dominated,and(4) solid electrolyte interface dominated.Notably,initial electrolytes in energy storage systems have been unable to play a decisive role in ionic selection.Utilizing a superior wettability strategy and simultaneously identifying the dominant ionic carrier can facilitate the tailored application of dendrite-free Na-K liquid anodes.     

非那雄胺合成工艺改进

非那雄胺能抑制5α-还原酶的活性,明显降低二氢睾酮水平,是一种治疗良性前列腺增生的有效药品。该合成工艺以甾烯酮酸为原料,将其与氯化亚砜反应,无须分离即与叔丁胺反应得17β-酰胺化合物,再氧化开环,环合,氢化,脱氢合成了非那雄胺。经元素分析、IR、1HNMR、13CNMR、MS分析表征了其结构。该法无须使用昂贵的2,2-二吡啶二硫化物和剧毒药品苯亚硒酸酐,且以乙酸铵代替氨气,降低了对设备的要求和腐蚀,更适用于工业生产。     

Interlaboratory Study to Improve the Quality Control of Methylmercury Determination in Sediment

The results are presented of an interlaboratory study on methylmercury (MeHg) in sediment carried out by a group of European laboratories within the framework of a project managed by the EC Standards, Measurements and Testing Programme (formerly BCR). The aim of this exercise was to evaluate the performance of current methods used for MeHg determination in sediment in order to improve the state-of-the-art prior to the certification of a candidate reference material. The paper describes the organization of the interlaboratory study, the preparation of the sediment material used, the techniques evaluated and the results obtained by the participating laboratories. The outcome of the collaborative project showed that certification could be contemplated, providing that certain analytical techniques were optimized, especially with regard to extraction methods.     

箔式聚丙烯电容器电压失效机理及工艺控制

箔式聚丙烯电容器在高温负荷及整机使用时易击穿。为了改善箔式电容器的抗电性能,对切割、卷绕、热压、焊接和浸渍工艺进行了研究。结果表明:切割时应尽量消除铝箔毛刺,卷绕时毛刺应卷在芯子端面,热压压强取5.88MPa,焊接时控制引线间距,浸渍应在真空度为–0.09MPa时进行。     

电子焊料的工艺性能及影响因素

通过分析焊料在钎焊过程中的行为,提出了电子焊料的工艺性能主要包括熔化/固化温度、抗氧化性、润湿性和漫流性。给出了各工艺性能的定义。分析表明:相关的影响因素主要包括合金的组成、纯度和化学均匀性;母材的成分、性质和表面的洁净度;液态焊料的表面张力;钎焊温度、气氛、助焊剂的活性;液态焊料表面膜的组成、结构和性能等。     

添加CaSO4·2H2O为晶种制备磷石膏半水硫酸钙晶须

以固体废弃物磷石膏为原料,在传统常压醇水热法的基础上添加CaSO₄·2H₂O为晶种制备半水硫酸钙晶须。采用单因素试验法探究了晶种含量、丙三醇含量和磷石膏质量分数对晶须结构和形貌的影响,确定晶须的最佳制备工艺条件。采用SEM和XRD对样品进行表征分析,实验结果表明:添加CaSO₄·2H₂O晶种制备晶须的长径比(49.29)比只添加丙三醇的样品的长径比(30.99)提高了近60%;当丙三醇与水的体积比(V)为1、晶种含量为1%、磷石膏质量分数为5%时制备的晶须的平均直径为0.65 μm,长径比达到了62.15,晶须的尺寸均匀。这说明添加1%CaSO₄·2H₂O晶种、V为1的丙三醇和质量分数为5%的磷石膏在常压下能制备出高长径比和尺寸均匀的半水硫酸钙晶须。     

基于数值计算的斜流泵级性能改进

采用CFD数值模拟的方法对斜流泵级内部三维紊流流场进行计算,预测了其效率-流量、扬程-流量特性,并与实验结果进行了对比验证。根据得到的流场结果,通过斜流泵级水力尺寸改进-数值模拟分析的循环工作,在最终改进的斜流泵级预测流场中减少了泵内流场的漩涡运动,避免了出口回流的产生,削弱了叶顶间隙泄漏涡,提高了斜流泵级的效率,改进了能量特性,得到了斜流泵级改进前后流场与效率的对比。