CH3O和CO在Pd(111)表面偶联反应机理的理论研究

采用DMol³程序包中的GGA-PW91方法, 结合周期平板模型, 对CH₃O和CO在Pd(111)表面的反应进行了系统研究. 计算结果表明, 吸附在Pd(111)表面顶位上的CO分子中C原子所带正电荷最多, 容易与亲核试剂反应, 化学吸附能稍低, 有利于在表面上移动发生亲电插入反应; CH₃O 在Pd(111)表面fcc穴位吸附稳定, O原子上所带的负电荷较多, 易被亲电试剂进攻. 过渡态搜索表明, Pd(111)表面顶位上的CO与fcc穴位上CH₃O反应生成CH₃OOC的为放热反应, 反应能垒较低, 有利于偶联反应的进行.     

水合醋酸铈直接热分解制备超细氧化铈及其抛光性能

Ultra fine ceria was prepared by calcining hydrate cerium acetate. The effects of pyrolysis temperature on the particle size, morphology, specific surface area and loose packing density of ceria were investigated, and the removal rate of optical glasses polishing by ceria was determined. The results show that with the increase of pyrolysis temperature, the loose deposit density and crystallinity increases and the specific surface area decreases, however, the particle size decreases firstly and then increases, the minimum medium particle size D₅₀ is 0.47 μm at pyrolysis temperature of 1 000 ℃. The SEM images of ceria prepared by the decomposition at 800 ℃ or at 1 100 ℃ show porous powders or quasi-sphere small particles with loosely agglomeration, respectively. It was found that the removal rate varied with pyrolysis temperature in preparation of ceria and the property of glass polished. The removal rate for three kinds of glasses was in the order of ZF7> F1> K9, and the maximum value appeared at around 1 000 ℃ for ZF7 and F1, and at around 1 100 ℃ for K9.     

燃料电池用聚合物质子交换膜的研究进展

质子交换膜（PEM）是质子交换膜燃料电池的核心组件之一,具有隔绝阴阳极、提供质子传递通道和阻止燃料渗透的作用. 商业化应用的全氟磺酸PEM存在燃料渗透严重、高温条件下导电性差和成本高的问题,开发性能优良的聚合物PEM显得很有必要. 本文讨论了近年来聚合物PEM的研究进展,分别从聚合物的主链、支链和交联结构角度介绍了分子结构对薄膜相分离、质子导电性、稳定性和电池性能等性能的影响,并讨论了聚合物分子结构设计方面存在的问题,最后对燃料电池用聚合物PEM在未来的发展方向进行了展望.     

A new Sequiterpenoid from Eupatorium adenophorum Spreng

A new sequiterpenoid compound 8aα-hydroxy-1-isopropyl-4,7-dimethyl-1,2,3,4,6,8a-hexahydro-naphthalene-2,6-dione(1),together with seven known compounds anti-HH-dimer-coumarin(2),(-)-5-exo-hydroxy-bomeol(3),O-hydroxyl cinnamic acid(4),9β-hydroxy-ageraphorone(5),10Hα-9-oxo-ageraphorone(6),10Hβ-9-oxo-ageraphorone(7)and 9-oxo-10,11-dehydroageraphorone 8,was isolated from the leaves of Eupatorium adenopho-rum Spreng.The structures were elucidated by IR,~1H and ~(13)C NMR,EIMS,HMBC and single-crystal X-ray spec-tral data.     

纯与掺杂CeO2的氧化还原性质及其催化领域的应用

概述了纯与掺杂CeO2氧化还原性质的研究状况及CeO2单独/主成分使用方式在催化领域中的应用.由于CeO2具有优异的储放氧性能,以及吸附气体和反应中间物能与几个Ce3 同时作用,其在氧化还原、合成气生产、有机合成和有机污染物降解等反应过程中呈现出良好的催化性能,而通过恰当的掺杂往往能使之得到进一步提高.最后,结合现状对其未来研究方向进行了展望.     

近红外光谱分析技术在快速分析上的应用

简要介绍了近红外光谱的原理、特点,综述了近红外光谱在农业、食品、制药、石油化工、高分子等领域快速分析上的研究及应用现状,并对近红外光谱的应用前景进行了展望．     

无患子皂苷成分的串联质谱分析

我们采用电喷雾串联质谱直接对无患子总皂苷中各皂苷成分进行鉴定. 该方法方便快捷, 适合于无患子或其它皂苷混合物的快速分析.     

甲基百里酚蓝-钐(III)配合物与鲱鱼精DNA的相互作用

在pH＝7.25的Tris-HCl缓冲溶液中, 以中性红(NR)作为光谱探针, 采用UV光谱、FS光谱、粘度等方法研究了甲基百里酚蓝(MTB)与稀土金属离子钐[Sm(III)]形成的配合物Sm(III)(MTB)₂与鲱鱼精DNA的作用机制. 确定了Sm(III)(MTB)₂与鲱鱼精DNA之间有嵌插作用方式存在, 说明Sm(III)(MTB)₂金属配合物能使鲱鱼精DNA的功能产生一定影响.     

MgSiO3状态方程的分子动力学模拟

The equation of state of MgSiO3 perovskite under high pressure and high temperature is simulated using the molecular dynamics method. It was found that the molecular dynamics simulation is very successful in accurately reproducing the measured molar volumes of MgSiO3 perovskite over a wide range of temperatures and pressures. The simulated equation of state of MgSiO3 perovskite matched experimental data at up to 140GPa at 300 K, as well as the fitting data of others and results from the first-principles simulation based on the local density approximation. The simulated equations of state of MgSiO3 perovskite at higher temperatures and higher pressures also correspond to the other calculations. In addition, the volume compression data of MgSiO3 perovskite is simulated up to 120 GPa at 300, 900, 2000 and 3000 K, respectively.