Influence of water molecule diffusion resistance force on electro-actuating characteristics of ionic polymer-metal

基于Tadokoro理论模型,采用有限元方法对离子交换膜金属复合材料 (ionic polymer metal composite, IPMC)的电致动特性进行了数值模拟. 通过比较求解控制方程中不考虑水分子扩散阻力和考虑水分子扩散力的两种计算模型, 着重探讨和比较了水分子扩散阻力对钠离子携带周围水分子的迁移运动规律和变形过程中各 个特征物理量的影响. 结果表明,控制方程中增加水分子扩散阻力这一非线性项,对最终的 宏观挠曲位移影响并不明显;但是对于钠离子浓度、等效应变、内部平衡力分布等物理量影 响很大;这种影响还具有区域性特征,主要集中于电极板附近区域,其他区域影响较弱. 控 制方程中增加水分子扩散力可以更准确地描述钠离子在迁移过程各物理量的变化规律.     

CeO2对等离子喷涂Cr2O3涂层抗热震性的影响

在Ｃｒ２Ｏ３陶瓷粉末中添加不同量的ＣｅＯ２,探讨ＣｅＯ２对等离子喷涂涂层抗热震性的影响,认为涂层的热震失效机制是在循环应力作用下发生在陶瓷层／粘结层界面的疲劳失效。在等离子喷涂Ｃｒ２Ｏ３涂层中添加３％ＣｅＯ２后,热震超裂寿命及失效寿命均得到明显提高。适量的ＣｅＯ２使微型裂纹呈现网状分布于涂层薄片内,具有释放涂层内应力的作用,可延缓裂纹的起裂和扩展,并使涂层内贯穿性孔洞减少,从而显著提高涂层的抗热震     

Study of Supported Bimetallic Pd-Pt Catalysts. Characterization and Catalytic Activity for Toluene Hydrogenation

Bimetallic Pd-Pt catalysts were prepared either by a surface redox reaction (RC catalysts) or by coimpregnation (CI catalysts). RC bimetallic catalysts show a higher sulfur resistance in the course of toluene hydrogenation in the presence of thiophene compared to monometallic palladium and CI bimetallic catalysts. A characterization of the RC catalysts by IR and EXAFS allows to propose a structure of the Pd-Pt crystallites which would explain these results.     

高碳高钢系高速钢的耐磨性研究

制备了不同成分的新型高碳高钢系高速钢,并与高铬铸铁对比考察了其耐磨性和磨损机理。结果表明：高碳高钡系高速钢的耐磨性明显优于高铬铸铁;其组织中的碳化物形态对耐磨性具有显著影响,其中具有细小及弥散分布的颗粒状ＭＣ型碳化物组织的试样的耐磨性最佳;其磨损机理为犁削和应力作用下碳化物的脆性碎裂及脱落。     

磺化聚醚醚酮/含硅二胺交联结构质子交换膜的制备与性能研究

采用含硅二胺(DMS)与磺化聚醚醚酮(SPEEK)反应,制备了交联结构质子交换膜.通过傅里叶变换红外(FTIR)和溶解实验证实交联结构的存在.采用热重分析仪(TG)、万能材料试验机和电化学综合站,研究了交联结构质子交换膜的热稳定性能、力学性能和交流阻抗.对质子交换膜的阻醇性能、水中尺寸稳定性能、吸水率、质子交换容量和质子传导率进行了详细探讨.交联改性可大幅度提高SPEEK膜的力学性能、阻醇性能以及尺寸稳定性能.通过扫描电镜(SEM)观察拉伸断面微观形貌,结果显示,DMS均匀分散在SPEEK基体中.将SPEEK/DMS交联结构质子交换膜与Nafion-117膜进行了性能对比分析,结果表明适度交联的质子交换膜具有比Nafion-117更优异的综合性能.20％的DMS对SPEEK进行交联改性后,膜的甲醇渗透系数为4.26×10-7 cm2·s-1,远低于Nafion-117的1.88×10-6 cm2·s-1;SPEEK/DMS-20％交联质子交换膜的有效选择性是Nafion-117的1.68倍.     

Metal transport ATPase genes from Cupriavidus metallidurans CH34: a transcriptomic approach

Cupriavidus metallidurans strain CH34 is a multiple metal resistant β-proteobacterium isolated from the sediments of a zinc metallurgical plant. This strain possesses a large diversity of heavy-metal-resistance genes that are located mostly on two large plasmids, pMOL28 and pMOL30. The metal efflux ATPases constitute the major mechanism by which metal ions are removed and pumped out from the cytoplasmic pool of thiol groups. The genome of C. metallidurans CH34 contains eight such P1-ATPases. This high number of ATPases, compared with the P1-ATPase content in other micro-organisms, is a typical feature of the adaptation of C. metallidurans CH34 to metal-rich biotopes. We performed a phylogenetic analysis, and used quantitative PCR to study the metal-specific induction of the ATPases genes and, for some of them, their neighbouring genes. One of the ATPases, a homologue of the E. coli zntA gene, was characterized in detail by analysing the phenotypes of zntA mutants in different genetic backgrounds. In addition to the already-reported sensitivity to Zn(II), Cd(II), and Pb(II), zntA mutants also displayed a higher sensitivity to Tl(I) and Bi(III), indicating that the ZntA protein might play a role in the tolerance of very large cations.     

土壤汞污染下水稻植株的傅里叶红外光谱特征

土壤汞污染对水稻的生长、发育以及稻米的品质均产生重要影响，目前，应用红外光谱研究汞对水稻植株中有机物分子结构的影响尚不深入。采取大田低、中、高三种汞污染水平下的水稻植株样品，应用傅里叶变换-红外光谱法(FTIR)测定水稻根、茎叶、籽粒三个器官的特征吸收峰，研究不同程度土壤汞污染对植株傅里叶红外光谱特征的影响。结果表明：土壤汞污染导致了汞在水稻植株中的累积，其含量分布为：根>茎叶>籽粒。水稻根、茎叶在3 428，2 922，2 851，2 364，2 344，1 750~1 500和1 150~935 cm-1等波数均受汞污染的影响，而汞污染下的水稻籽粒仅在3 426，2 361，2 335和1 750~1 300 cm-1波数发生了变化。综合分析水稻植株各器官的FTIR光谱特征，可能说明：汞胁迫降低了水稻根、茎叶和籽粒中碳水化合物，刺激了根中羧酸、半乳糖、饱和脂类和茎叶中多种多糖的生成。水稻根和茎叶是阻抑汞迁移与侵害的主要器官。根部似乎是在茎叶加强多糖类物质的生成并向根部转运营养物质的基础上通过分泌有机酸和增强细胞壁、膜的形成，使其与Hg螯合和吸附，阻止汞向根内的迁移来实现抗汞胁迫的。可以通过加强根与茎叶的抗汞过程来降低汞对水稻尤其是稻米的侵害。在种植管理中不仅要重视汞在稻米中的积累，还应当重视汞对水稻生长发育和稻米品质的影响。     

Synthesis,characterization, AC conductivity,and diode properties of polyaniline–CaTiO3 composites

Polyaniline–CaTiO₃ composites of different weight percentages were prepared by in situ polymerization. The prepared composites were characterized by Fourier transform infrared spectroscopy for structural studies, and a morphology analysis was carried out by scanning electron microscopy studies. Real and imaginary parts of the complex impedance were determined for given samples as a function of frequency. Current–voltage and capacitance–voltage measurements were also carried out. The carrier mobility μ values of neat polyaniline and polyaniline–CaTiO₃ composites were found to be 5.37 × 10^?3 and 2.73 × 10^?2, respectively, and a significant enhancement, as compared with the reported data, was observed. Therefore, this study may provide a better route for technological applications in all fields in the near future and can also be represented by a pure electronic model. Copyright © 2013 John Wiley & Sons, Ltd.     

Negative differential thermal resistance in a double-chain system

Using nonequilibrium molecular dynamics simulations, we study the phenomenon of negative differential thermal resistance (NDTR) in a double-chain system. We investigate the dependence of NDTR on the external potential, inter- and intra-chain interaction and the system size. It is reported that the NDTR can occur in a small double-chain system with weak external potential and weak inter- and intra-chain interaction. We also present the influence of the external potential, inter- and intra-chain interaction and the system size on the heat current of the system through the phonon spectral analysis.