溶胶凝胶法制备三维规则排列大孔TiO2材料

以聚苯乙烯微球 (LatexSphere)离心后形成的三维规则排列的胶晶 (colloidcrystal)作模板 ,用钛酸丁酯、水、乙醇等配制的溶胶填充微球之间的间隙 ,然后原位形成凝胶 ,最后通过焙烧除去微球得到三维规则排列大孔TiO2 材料 (3DOM)。溶胶的浓度一般控制在 0 5～ 1 0md/L之间。焙烧过程的升温速度应控制在 5℃ /min以下。得到的样品表面可观察到五颜六色的彩光。从SEM照片可观察到 ,球形孔大小均匀 ,排列整齐 ,孔壁填充完全。孔径在 5 30nm左右 ,孔的排列呈面心立方结构 ,孔与孔之间由小孔窗相互交连。XRD表明孔壁含有锐钛矿和金红石两种晶型 ,2种晶型质量分数大约各占 5 0 %。     

Accurate forecasting of the undecided population in a public opinion poll

The problem of pollsters is addressed which is to forecast accurately the final answers of the undecided respondents to the primary question in a public opinion poll. The task is viewed as a pattern‐recognition problem of correlating the answers of the respondents to the peripheral questions in the survey with their primary answers. The underlying pattern is determined with a supervised artificial neural network that is trained using the peripheral answers of the decided respondents whose primary answers are also known. With peripheral answers as inputs, the trained network outputs the most probable primary response of an undecided respondent. For a poll conducted to determine the approval rating of the (former) Philippine president, J. E. Estrada in December 1999 and March 2000, the trained network predicted with a 95% success rate the direct responses of a test population that consists of 24.57% of the decided population who were excluded in the network training set. For the undecided population (22.67% of December respondents; 23.67% of March respondents), the network predicted a final response distribution that is consistent with the approval/disapproval ratio of the decided population. Copyright © 2002 John Wiley & Sons, Ltd.     

新型固体酸SO_4~(2-)MoO_3-TiO_2催化合成苹果酯

自制了一种新固体酸催化剂SO2 -4MoO3 -TiO2 ,FT -IR谱图表明 ,催化剂表面具有强酸中心 ,该催化剂对苹果酯合成的活性高 ,并得到该反应的优化条件如下 :乙酰乙酸乙酯 0 .3mol,乙二醇 0 .6mol,环己烷 30ml,催化剂 3g ,反应温度 110℃ ,反应时间 1.5h ,在此条件下 ,苹果酯产率达 90 % ,且催化剂易回收 ,具有较好的重复使用性能     

基于代理的校园网计费管理系统

根据目前Cernet校园网典型结构,设计了一种适应性广、通用性强的校园网计费管理系统,探讨了使用代理服务器进行计费的主要功能和工作流程.     

(E)-3-(3,4-二甲氧基苯基)-2-氰基丙烯酸乙酯的合成和晶体结构

标题化合物C14 H15O4N(3)是由 3,4 二甲氧基苯甲醛 (1) 与氰乙酸乙酯 (2 ) 在KF/蒙脱土催化下以N ,N 二甲基甲酰胺 (DMF)作溶剂反应而得 .结构通过单晶X射线衍射分析确定 ,其晶体属于单斜晶系 ,空间群P2 1/n ,a =1.310 1(3) ,b =0 .80 32 (2 ) ,c =1.385 4 (2 )nm ,β =114 .2 1(1)° ,Mr=2 6 1.2 7,V =1.32 96 (5 )nm3 ,Dc=1.30 5 g/cm3 ,Z =4 ,μ(MoKα) =0 .0 96mm-1,F(0 0 0 ) =5 5 2 .晶体结构用直接法解出 ,使用全矩阵最小二乘法对原子参数进行修正 ,最后的偏离因子R =0 .0 398,RW =0 .0 816 .单晶X衍射分析表明标题化合物为 (E)式异构体产物 ,说明该反应具有立体选择性 .     

安徽省芜湖市市区大气SO2污染特征分析

对1993-2002年芜湖市区大气SO2进行了连续10年的观测,结果表明,芜湖市区大气SO2质量浓度10年平均值为0.023 5 mg/m3,由1993年的0.052 mg/m3减少到2002年的0.012 mg/m3,年平均减少率为4%.2000年以来减少速度加快,大气SO2质量浓度日变化总特征是早晨高、午后低,季节变化是冬季、春季高,夏季、秋季低.同时对芜湖市区大气SO2发展趋势作了分析,并提出了防治和减轻污染的建议.     

具有纳米结构的TiO2纤维光催化氧化活性

研究了具有纳米结构,高比表面的锐钛矿TiO2纤维在光催化降解苯酚体系中的氧化性能,发现其活性与P25相当;通过加羟基自由基猝灭剂证实了羟基自由基(HO·)对苯酚降解的贡献;而通过加空穴猝灭剂则观察到明显的空穴(h+)效应.并通过KI氧化反应进一步研究了催化剂表面上的空穴效应,结果表明,TiO2纤维上的光生空穴比P25稳定,其空穴量子产率是后者的3.3倍.     

UPS网络控制和电压波形显示的研究

对目前在UPS方面研究的焦点问题作了阐述 ,并重点介绍了UPS网络控制系统的实现方法、系统功能和技术特点     

基于特征造型的注塑件CAD/CAE研究

以某电器零件的特征造型与注塑分析模拟为例，介绍了Pro/Engineer的特点以及在注塑件产品开发中的应用。     

THE TRANSFER BEHAVIOUR OF SOME CATIONS AT WATER／NITROBENZENE INTERFACE BY SEMIDIFFERENTIAL CYCLIC VOLTAMMETRY

The transfer of Sr~(2+) and Ba~(2+) ion, facilitated by 18-Crown-6 present in the aqueous phase, and of succinylcholine ion at w/nb interface were investigated by semi-differential cyclic voltammetry. A good polarographic curve of succinylcholine ion dissolved in water was obtained in the system of 0.01 mol/l LiCl (w)——0.01 mol/l TBATPB (nb). The peak current is directly proportional to the concentration of SC~(2+) ion. It can be used for the determination of SC and the detection limit is 1.05×10~(-5) mol/l.The apparent D~w and D~(nb) have been estimated. The transfer of Sr~(2+) and of Ba~(2+) at the interface are facilitated by 18-Crown-6 present in the aqueous phase and the peak current is directly proportional to the concentration of 18-Crown-6 in water. This method can be used for the determination of the complexing agent and for the stability constant of the complex formed in the aqueous phase.All the experimental results are in keeping with the theoretical.