A Convenient Method for the Stereoselective Synthesis of 7αHydroxycholesterol

7-Hydroxyderivativesofcholesteroldisplayawidevarietyofbiologicalactivities'-',mostofwhicharerelatedtothephysiologicalcontrolofcholesterolbiosynthesisandantitumoractivity.Inearlyreports',the7-hydroxycholesterolswerepreparedbythesequenceofacetylation,allylicchromicoxidation,andhydridereduction.Generally,theproductisamixtureof7a-and76-epimerswhichisdifficulttobeseparated.V.Kumaretal5improvedthisprocedurebyusingstereospecificreducingreagentsinsteadofthesimplehydride.7a-and7o-epimerscouldbeobtained…     

Sr1-xLaxTiO3的高温高压合成及XPS研究

 利用高温高压方法合成了有稀土元素La掺杂的钙钛矿氧化物Sr_1-xLa_xTiO₃。XRD测试表明，在x≤0.5时，样品基本为单相，呈立方相；晶胞体积随x的增加而增加，在x=0.4时开始减小。XPS测量发现，样品中存在Ti离子的变价。讨论了Ti离子价态的变化对晶格参数的影响。     

Conflict resolution in fuzzy environment

Conflict resolution methodology is discussed with fuzzified Pareto frontier. Four solution concepts, namely, the Nash solution, the generalized Nash solution, the Kalai-Smorodinsky concept, and a solution method based on a special bargaining process are examined. The solutions are also fuzzy, the corresponding payoff values are fuzzy numbers, the membership functions of which are determined. Three particular cases are considered in the paper. Linear, quadratic, and general nonlinear Pareto frontiers with known shape are examined.     

Large area bolometers for millimeter-wave power calibration

An accurate monolithic power meter has been developed for millimeter-wave applications. The detector is a large-area Bismuth bolometer, integrated on a fused-Quartz substrate. It simply measures the temperature change caused by the absorption of millimeter-wave radiation. The power meter is simple to fabricate, inexpensive, and can be easily calibrated using a low-frequency network. The measured responsivity for a 50 bolometer, with an area of 1×1cm, at a bias of 1V. and a video modulation of 100Hz, is 1mV/W. The noise spectrum exhibits a 1/f rolloff till 1KHz, and is limited by the Johnson noise for higher frequencies. The NEP of the detector is 3WHz^–1/2 at a video modulation of 1KHz. It is possible to decrease the current NEP by fabricating bolometers with higher responsivities. Possible application areas are absolute power calibration and localized power density measurements at millimeter and submillimeter wavelengths.     

YBO3:Eu荧光粉的水热法制备及形貌控制

用水热法在低于300℃成功地制备出具有不同形貌的YBO3:Eu3+荧光粉,其反应温度比固相反应了约800℃.研究了初始原料、pH值、反应温度、反应溶剂和催化剂等条件对目的产物形貌及粒度的,得到了具有Vaterite结构、粒度分布均匀的球形荧光粉的最佳合成工艺.在254nm激发下,水热法的球形Y0.95Eu0.05BO3荧光粉最强发射峰位于598nm处,属于Eu3+的5D0→7F1的跃迁,是固相反应所品的1.5倍.这些结果表明,在PDP和荧光灯等显示和照明用荧光粉的制备中水热法具有潜在的应用.     

N-(邻-氯苯基)氨基乙酸铜(Ⅱ)和N-(邻-甲基苯基)氨基乙酸铜(Ⅱ)的合成、晶体结构和电子结构

合成了N-(邻氯苯基)氨基乙酸铜(Ⅱ)和N-(邻甲基苯基)氨基乙酸铜(Ⅱ)的单晶体,测定了它们的晶体结构,并对其电子结构进行EHMO计算。N-(邻氯苯基)氨基乙酸铜(Ⅱ)属单斜晶系,空间群P2₁/a.a=8.786(4),b=7.777(2),c=11.956(2)Å,β=96.01(3)°,V=812.4ų,Z=2,D_c=1.77g·cm^-3;N-(邻甲基苯基)氨基乙酸铜(Ⅱ)属单斜晶系,空间群P2₁/a,a=8.925(6),b=7.973(8),c=11.856(9)Åβ=96.23(6)°,V=838.6Å,Z=2,D_c=1.55g·cm^-3。两配合物互为异质同晶。配合物中,铜原子为分子的对称中心,并与两个配位体的两个羧基氧和两个氨基氮原子形成四方形配位结构,平均Cu-O键长为1.902Å,Cu-N为2.050Å。量子化学计算表明,在配位键的形成中,铜原子的d轨道的作用均不大,但配体中苯环上取代基的性质对Cu-N键强度有一定影响。     

ZnO超微粒子光催化氧化降解n-C7H16的研究

利用ZnO光催化氧化技术对气相n-C7H16进行了降解研究，考察了氧气、水燕气体积分数等因素对n-C7H16光催化氧化的影响，利用气相色谱－质谱联用仪和气相色谱仪对气相光催化反应过程中的气体组成进行了定性分析，并对主要中间产物丙醛进行了定量分析，结果发现，ZnO超微粒子光催化氧化n-C7H16的降解率较高，n-C7H16绝大部分被完全氧化成CO2，探讨了n-C7H16光催化氧化反尖的动力学行为及机理。     

A Highly Sensitive Spectrophotometric Assay of Bleomycins Based on the Fading Reaction of Some Halofluorescein Dyes

In weak acidic medium, anticancer antibiotics bleomycin A5 （BLMA5） and bleomycin A2 （BLMA2） can react with halofluorescein dyes such as erythrosin （Ery）, eosin Y （EY）, eosin B （EB） and rose bengal （RB） by virtue of electrostatic attraction and hydrophobic force to form the ion-association complexes, which can result in the fading reactions of four halofluorescein dyes. The maximum fading wavelengths of these four dyes were located at 527 nm for Ery, 515 nm for EY, 517 nm for EB and 546 nm for RB, respectively. The decrements of absorbance （AA） were directly proportional to the concentrations of bleomycin in a certain range. A new method for the determination of bleomycins anticancer drugs based on fading reactions of halofluorescein dyes has been developed. The method was not only highly sensitive but also simple and rapid. The molar absorptivities （ε） ranged from 1.5 × 10^5 to 7.5 × 10^5 L·mol^-1·cm^-1. It was applied to determination of the bleomycins in human serum, urine and rabbit serum samples. In this work, the spectral properties and the optimum reaction conditions were investigated. The structure of ion-association complexes and the reaction mechanism were discussed.