Cr2O3和CrO3/Cr2O3催化剂的2-氯-1,1,1-三氟乙烷气相氟化反应的活性物种和失活

采用沉淀法和浸渍法制备了2种铬基（Cr₂O₃和CrO₃/Cr₂O₃）催化剂,用于气相氟化2-氯-1,1,1-三氟乙烷合成1,1,1,2-四氟乙烷。研究发现含有低价铬（Cr³⁺）物种的Cr₂O₃催化剂上2-氯-1,1,1-三氟乙烷的稳态转化率为18.5%,而含有高价铬（Cr⁶⁺）物种和低价铬（Cr³⁺）物种的CrO₃/Cr₂O₃催化剂初始转化率达到30.6%,然而存在明显的失活。含有Cr⁶⁺物种的CrO₃/Cr₂O₃催化剂的2-氯-1,1,1-三氟乙烷氟化反应初始TOF值为1.71×10^-4 mol_HCFC-133a·mol_Cr（Ⅵ）^-1·s^-1,高于含有Cr³⁺物种的Cr₂O₃催化剂（4.16×10^-5 mol_HCFC-133a·mol_Cr（Ⅲ）^-1·s^-1）。Cr₂O₃催化剂在氟化反应前后催化剂的物相结构保持不变;而含有高价铬物种的CrO₃/Cr₂O₃催化剂经HF反应后生成了CrO_xF_y活性物种。然而,CrO_xF_y物种在反应中挥发或转化成稳定但无活性的CrF₃,从而导致催化剂失活。     

Effect of substrate temperature on microstructure and optical properties of single-phased Ag20 film deposited by using radio-frequency reactive magnetron sputtering method

Using a radio-frequency reactive magnetron sputtering technique, a series of the single-phased Ag20 films are deposited in a mixture of oxygen and argon gas with a flow ratio of 2：3 by changing substrate temperature （Ts）. Effects of the Ts on the microstructure and optical properties of the films are investigated by using X-ray diffractometry, scanning electron microscopy and spectrophotometry. The single-phased Ag20 films deposited at values of Ts below 200℃ are （111） preferentially oriented, which may be due to the smallest free energy of the （111） crystalline face. The film crystallization becomes poor as the value of Ts increases from 100℃ to 225℃. In particular, the Ag20 film deposited at Ts=225℃ loses the （111） preferential orientation. Correspondingly, the film surface morphology obviously evolves from a uniform and compact surface structure to a loose and gullied surface structure. With the increase of Ts value, the transmissivity and the reflectivity of the films in the transparent region are gradually reduced, while the absorptivity gradually increases, which may be attributed to an evolution of the crystalline structure and the surface morphology of the films.     

钴卟啉过氧中间体向环己烷夺氢的密度泛函计算

采用密度泛函理论计算方法模拟了简单钴卟啉过氧中间体PCo-O2与环己烷C6H12的作用,分析了反应路径中各驻点能量和反应过渡态分子构型。研究结果表明,PCo-O2向底物环己烷夺氢的反应可以延正方向进行,二线态PCo-O2更具反应活性,反应过程中Co-O键得到加强,O-O键被削弱。依据理论计算结果,探讨了四苯基钴卟啉催化环己烷氧化生成环己醇和环己酮的反应机理,指出反应延Lyons高价金属氧代物机理生成环己醇,而反应循环中产生的烷基自由基可以延烷基过氧化过渡金属配合物反应机理进行生成环己酮。     

有机药物分子与DNA相互作用的研究进展

综述了有机药物分子与DNA相互作用的模式、影响因素、并着重介绍了其相互作用的电化学等研究方法,概括了其近几年的研究进展,并在此基础上提出了在药物分子与DNA相互作用的研究工作中应解决的问题.     

对甲基苯磺酸亚铈催化一锅法合成取代2,3-二氢-4(1H)-喹唑啉酮

以对甲基苯磺酸亚铈为催化剂,靛红酸酐、醛和铵盐或伯胺为原料,在乙醇水溶液中三组分一锅法合成了一系列单取代和双取代2,3-二氢-4(1H)-喹唑啉酮衍生物。考察了溶剂条件及催化剂用量对产率的影响。经催化剂循环研究,催化活性无明显变化。产物的结构通过熔点、IR、1H NMR、13C NMR、质谱和元素分析进行测定和结构表征。     

一类不确定非线性系统的多约束鲁棒H∞控制

针对一类不确定的T-S模糊模型,给出了反馈控制器存在的充分条件,该控制器使得闭环极点被配置在给定的线性矩阵不等式(LMI)区域内,同时满足系统对H∞范数和方差约束的要求.基于这一条件和并行分布补偿技术(PDC),借助于LMI和凸优化方法,得出一个全局鲁棒H∞控制器的解析式.最后,通过一个仿真例子,说明该方法的可行性.     

机器人实践教学的探讨和优势

机器人是集机械、电子、控制、计算机、传感器、人工智能等多学科先进技术于一体的智能仪器。机器人实践教学在学习上充分渗透了研究性学习的思想,实践性非常强。初步机器人教学实践措施表明,在电子信息类专业积极开展机器人实践教学,有助于培养和提高学生的实践和创新能力,有助于促进实践教学改革。     

Effect of substrate temperature on microstructure and optical properties of single-phased Ag2O film deposited by using radio-frequency reactive magnetron sputtering method

Using a radio-frequency reactive magnetron sputtering technique,a series of the single-phased Ag2O films are deposited in a mixture of oxygen and argon gas with a flow ratio of 2:3 by changing substrate temperature(T s).Effects of the T s on the microstructure and optical properties of the films are investigated by using X-ray diffractometry,scanning electron microscopy and spectrophotometry.The single-phased Ag2O films deposited at values of T s below 200℃ are(111) preferentially oriented,which may be due to the smallest free energy of the(111) crystalline face.The film crystallization becomes poor as the value of T s increases from 100℃ to 225℃.In particular,the Ag2O film deposited at T s = 225℃ loses the 111 preferential orientation.Correspondingly,the film surface morphology obviously evolves from a uniform and compact surface structure to a loose and gullied surface structure.With the increase of T s value,the transmissivity and the reflectivity of the films in the transparent region are gradually reduced,while the absorptivity gradually increases,which may be attributed to an evolution of the crystalline structure and the surface morphology of the films.     

顺序注射停流分光光度法测定痕量碘

食物中碘的含量一直是人们关注的问题,研究食物中微量碘的分析方法具有重要的现实意义.目前测定碘的方法主要有色谱法[1,2]、荧光法[3,4]、分光光度法[5,6]等.