贮氢合金氧含量及添加剂对电池性能的影响

为了改善MH Ni电池的性能 ,在由不同的处理方法得到MmNi3 .55Co0 .75Mn0 .4 Al0 .3 贮氢合金表面氧含量不同的基础上 ,通过电池的充放电测试 ,以及电池充放电及静止过程中内压变化的测量 ,研究了合金表面不同氧化物含量对金属氢化物电极和电池有关性能的影响规律。结果表明 :贮氢合金的表面氧化物含量越低 ,合金的质量比容量便越高 ,同时负极的初始活化性能越好 ,负极的工作电位越负 ,电池的内压越低。在此基础上 ,通过向负极中加入 1%化学镀催化剂的乙炔黑 ,用以加速氧的复合 ,结果使MH Ni电池充电时的内压进一步降低。     

不对称Reformatsky反应的研究进展

综述了近年来不对称Reformatsky反应在有机合成中的应用。     

有机高分子聚合物LPPP异质结构微腔调谐器可靠性的研究

研究表明有机半导体微腔效应可通过简单地调节有机发光层的厚度来实现。实验结果还指出,由空穴传输型的ＬＰＰＰ和电子转移型掺杂的Ａｌｑ构成的异质结构的微腔器能极大地改进其可靠性。同时用金刚石电极代替金属电极也能提高有机发光器件的稳定性。     

十两茶提取物抗高脂诱导家兔动脉粥样硬化形成涉及调节ADMANO通路

目的:观察十两茶提取物对高脂诱导家兔动脉粥样硬化的影响。方法:家兔高脂饲料喂养4周后,分别灌胃给予不同剂量的十两茶提取物(25、50和100mg/kg),共4周。实验结束后,颈动脉取血检测红细胞变形能力,测定血脂、NO、非对称二甲基精氨酸(ADMA)和丙二醛(MDA)含量;分离胸主动脉检测脂质斑块面积和血管内皮依赖性舒张功能。结果:十两茶提取物能剂量依赖性地降低高脂饲养家兔血清总胆固醇和低密度脂蛋白水平,同时显著减少主动脉粥样斑块面积和改善血管内皮舒张功能及红细胞变形能力。十两茶提取物显著降低血清MDA和ADMA含量和增加NO水平,且呈剂量依赖性。结论:十两茶提取物具有抗动脉粥样硬化作用,其机制与抑制脂质过氧化、调节ADMANO系统,改善血管内皮功能和红细胞变形能力有关。     

Miniaturization limits for single-chamber micro-solid oxide fuel cells with coplanar electrodes

Single-chamber solid oxide fuel cells with coplanar microelectrodes were operated in methane–air mixtures (R_mix = 2) at 700 °C. The performance of cells with one pair of NiO–YSZ (yttria stabilized zirconia) anode and (La_0.8Sr_0.2)_0.98MnO₃–YSZ cathode, arranged parallel on a YSZ electrolyte substrate, was found to be significantly dependent on the electrode width. For an interelectrode gap of 250 μm, cells with average electrode widths exceeding 850 μm could establish a stable open circuit voltage (OCV) of 0.8 V, while those with widths less than 550 μm could not establish any OCV. In the intermediate range, the cells exhibited significant fluctuations in voltage and power under our testing conditions. This behavior suggests that a lower limit to electrode dimensions exists for cells with single electrode pairs, below which neither a stable difference in oxygen partial pressure, nor an OCV, can be established. Conversely, increasing the electrode width imposes a penalty in the form of an increase in the cell resistance. However, both size limits can be circumvented by employing multiple pairs of microscale electrodes in an interdigitated configuration.     

An Efficient Approach to Chiral Ferrocene‐Based Secondary Alcohols via Asymmetric Hydrogenation of Ferrocenyl Ketones

P‐Phos‐ruthenium‐DPEN precatalysts have been found to be efficient for the asymmetric hydrogenation of various ferrocenyl ketones. The use of (R)‐xylyl‐P‐PhosRuCl₂(R,R)‐DPEN generated chiral ferrocenylethanol in 99.3% e.e. with >99% conversion in a 150‐g scale.     

Polyethylene Glycol as an Environmentally Friendly and Recyclable Reaction Medium for Enantioselective Hydrogenation

Polyethylene glycol (PEG) was found to be an inexpensive, non‐toxic and recyclable reaction medium for ruthenium‐ and rhodium‐catalyzed asymmetric hydrogenation of 2‐arylacrylic acids (Ru‐catalyzed CC bond reduction), enamides (Rh‐catalyzed CC bond reduction), β‐keto esters and simple aromatic ketones (Ru‐catalyzed CO bond reduction). In all cases, high catalytic activities and enantioselectivities have been achieved, which are comparable to those obtained in conventional organic solvent systems. The Ru and Rh catalysts prepared with commercially available chiral diphosphine ligands could be readily recycled by simple extraction, as in the case of ionic liquids, and reused up to nine times without obvious loss of catalytic activity and enantioselectivity. The reduced products were obtained from the extracts in high isolated yields. These results indicate that PEGs as new reaction media are attractive alternatives to room temperature ionic liquids.     

A 100 Gram‐Scale Production of a Key Building Block of Antibacterial Vancomycin: The Use of an Air‐Stable Chiral Zirconium Catalyst and Complete Recovery of a Silicon Source in Catalytic Asymmetric Mukaiyama Aldol Reaction

We have achieved a 100 gram‐scale production of anti‐(2S,3S)‐β‐(p‐benzyloxy‐m‐chloro)phenyl‐N‐trifluoroacetyl‐L ‐serine methyl ester ( 1 ) in high yield with high diastereo‐ and enantioselectivities based on a catalytic asymmetric Mukaiyama aldol reaction. The use of an air‐stable zirconium‐molecular sieves combined catalyst [(R)‐I₄‐ZrMS] facilitates easy manufacturing operation and reproducibility. Moreover, this is the first example of the complete recovery of the silicon source in a Mukaiyama aldol reaction.     

Second‐Generation N,O‐[2.2]Paracyclophane Ketimine Ligands for the Alkenylzinc Addition to Aliphatic and Aromatic Aldehydes: Scope and Limitations

Second generation N,O‐[2.2]paracyclophane ketimine ligands were investigated for their ability to catalyze the 1,2‐addition of alkenylzinc reagents to aliphatic and aromatic aldehydes with special focus on functionalized substrates. For aliphatic aldehydes, which have always been challenging in this field, remarkably high enantiomeric excesses could be determined (50–95 % ee). However, alkenylzinc reagents bearing heteroatoms proved to be demanding substrates for this system.     

Efficient Enantioselective Hydrosilylation of Aryl Ketones Catalyzed by a Chiral BINAP‐Copper(I) Catalyst‐Phenyl(methyl)silane System

The Cu(I)‐chiral diphosphine (BINAP) system was found to efficiently catalyze the hydrosilylation of aryl alkyl ketones with excellent enantioselectivities by using phenyl(methyl)silane as stoichiometric hydride source.