Electrochemical and Spectroscopic Behaviour of Bis(2‐mercaptopyridine‐N‐oxide)oxovanadium(IV)

The complex [VO(MPO)₂] (MPO = deprotonated 2‐mercaptopyridine N‐oxide) was synthesized and characterized by IR spectroscopy. Its electrochemical behaviour was investigated by cyclic voltammetry in different organic solvents. The V^IV/V^V and V^IV/V^III couples could be identified. The nature of the electroactive species is strongly dependent on the solvent. The results are discussed in terms of a reaction mechanism describing the characteristics of the electron transfer processes and the involved chemical reactions, and the stability of the complex in each solvent was also determined. The electronic spectra of the investigated solutions gave additional support to the proposed mechanisms.     

石吊兰的红外光谱分析

本论文首次采用傅立叶变换红外光谱法对云南当地药材石吊兰的根、茎、叶和花进行了对比研究, 比较了它们红外光谱的异同。结果表明: 同一株石吊兰的不同部位, 它们吸收峰的峰形大体相同, 但由于它们所属的部位不同, 它们的化学成分和相对含量出现差异, 它们红外光谱的吸收峰位置和吸收强度均有不同。分析获得的红外光谱, 发现石吊兰的根、茎、叶和花均有不同的缺峰现象。根据各种化学键和官能团振动所引起的吸收峰形状和范围, 判断推理出石吊兰中含有生物碱、黄酮类化合物、石吊兰素(即黄酮甙元)和β-谷甾醇等化合物。石吊兰的红外光谱分析为石吊兰的定量分析和定性分析提供了科学依据。     

鼠曲草的红外光谱分析

利用傅立叶红外光谱仪测定了鼠曲草的根、茎、叶和花的红外光谱图, 分析比较了它们在光谱图上的差异, 尽管它们的吸收峰的强度和位置有所差异, 但是通过对红外光谱图的主要特征峰的峰位和强度的分析, 推断出它们均含有氨基酸、淀粉、甙类、酮类、挥发油、豆甾醇等物质。此结果对鼠曲草的开发和利用提供了科学依据。     

Interpolation of compact bilinear operators among quasi‐Banach spaces and applications

We study the interpolation properties of compact bilinear operators by the general real method among quasi‐Banach couples. As an application we show that commutators of Calderón–Zygmund bilinear operators are compact provided that , and .     

齐次树上三次循环树指标马氏链的强极限定理

首先给出齐次树上三次循环树指标马氏链的定义,利用构造鞅的方法,研究齐次树上三次循环树指标马氏链的强极限定理,并给出其状态及状态序偶发生频率的强大数定律.     

基于近似尺度不变特征转换的序列图像融合算法(英文)

在分析了尺度不变特征转换算法特点的基础上提出了一种近似尺度不变特征转换算法,该算法改变了传统尺度不变特征转换算法的框架,将尺度不变特征转换描述符看作是一种特殊的Harris算子,该算法既保留了尺度不变特征转换描述符的优点又降低了计算量.另外,为了提高特征匹配的精度,给出了一种新的特征点对提纯算法.实验结果表明,近似尺度不变特征转换算法在不影响匹配性能的前提下大大缩短了处理时间,经过提纯后的特征点对匹配性能显著提高,最终得到的全景图像过渡平稳,重叠区域没有显著的痕迹.     

固相萃取-毛细管气相色谱法测定中草药及其土壤中多种有机氯农药残留量

建立了中草药及其土壤中多种有机氯农药残留量的固相萃取-毛细管气相色谱(SPE-CGC)分析方法,并对7种中草药及其土壤中多种有机氯农药残留量的相关性进行了初步研究。样品以正己烷-丙酮用超声波提取,Florisil(1 g)固相萃取小柱快速净化提取物。采用SPB-5弹性石英毛细管柱分离样品,GC-ECD检测7种中草药及其土壤中的13种有机氯农药的残留量。方法的线性范围为1.26×10-10~2.24×10-7g/mL;检出限为6.4×10-11~6.1×10-10g/mL;加样平均回收率为87.3%~104.4%(RSD为1.1%~7.0%)。     

A Conversation with William A. Fowler – Part II

Physicist William A.Fowler initiated an experimental program in nuclear astrophysics after World War II. He recalls here the Steady State versus Big Bang controversy and his celebrated collaboration with Fred Hoyle and Geoffrey and Margaret Burbidge on nucleosynthesis in stars. He also comments on the shift away from nuclear physics in universities to large accelerators and national laboratories.John Greenberg received his Ph.D. degree from the University of Wisconsin and was Caltech research fellow in history from 1980–1984. The Editors were saddened to learn that he died while this interview was in press. Requests for reprints may be directed to Judith R. Goodstein, Institute Archives 015A-74, Caltech, Pasadena, CA 91125 USA; e-mail: jrg@caltech.edu.     

Thermochemistry of some mono-substituted iodine fluorides and a comparison of gas and solid phase structures

The heat of formation of iodine trifluoride, obtained from an ab initio calculation of its heat of dismutation to mono- and penta-fluorides, was close to their average value. The mean bond dissociation energies of these iodine fluorides is almost invariant. The reduction couples between penta and trifluoro, or tri and mono-fluoro compounds, were employed to calculate formation heats of phenyl and trifluoromethyl iodine fluorides via similar isodesmic reactions. The substituted derivatives were stronger oxidants than the unsubstituted iodine fluorides as quantified by their redox couples. Similarly the corresponding chloro-fluorides were stronger oxidants than the iodo-fluorides. Heats of formation of other iodine fluoride derivatives can be obtained by additivity methods. Recent X-ray structures, when compared with calculated gas-phase structures, showed a lesser tilt of axial I-F bonds to the vertical in the solids probably due to intermolecular association. Rotational barriers around C-I bonds were small enough to permit almost free rotation at ambient temperatures.     

不同气氛环境中钢/铜摩擦副的高速干滑动摩擦磨损特性研究

采用MMS-1G型高温高速摩擦磨损试验机研究了在氧气和二氧化碳2种气氛环境中CrNiMo钢/H96黄铜摩擦副的高速干滑动摩擦磨损特性,采用扫描电子显微镜和X射线光电子能谱仪对CrNiMo钢销试样的磨损表面形貌及其元素的化学状态进行分析,结合摩擦表面宏观温度的测量,分析了不同气氛环境中pv值对摩擦副摩擦磨损特性的影响.结果表明,在不同气氛环境中,摩擦副表现出完全不同的摩擦磨损特性,在二氧化碳气氛环境中,摩擦副的摩擦系数与CrNiMo钢的磨损率均高于氧气气氛环境中,这是由于2种气氛环境中的摩擦表面温度及其磨损机制的差异所致.二氧化碳气氛环境中的摩擦表面温度高于氧气气氛环境中的摩擦表面温度,其主要磨损机制为磨粒磨损、金属流变和粘着磨损;而氧气气氛环境中主要表现为氧化磨损和粘着磨损.