农林高校基础化学多层次课程体系和教学内容的改革与实践

以农林高校基础化学课程体系和教学内容改革为抓手,构建了农科特色鲜明的多层次课程体系,优化设计了教学内容,增强了教学的针对性,突出了学生个性的发展,为农科院校创新人才的培养奠定了重要的化学基础。     

酰胺基团对Gemini表面活性剂表面活性和聚集行为的影响

本文合成了含酰胺基团和不含酰胺基团的两类Gemini阳离子表面活性剂,测定了其表面活性参数,研究了酰胺基团对表面活性剂的表面活性和聚集行为的影响。结果表明,酰胺基团提高了Gemini阳离子表面活性剂的临界胶团浓度,降低了胶团聚集数,增强了胶团微极性,增大了表面活性剂的饱和吸附量。     

促进学生认识发展的“电离和离子反应”专题的单元整体教学研究

系统梳理了电离、离子反应专题的已有研究,分析了电离、离子反应内容对学生认识发展的作用,进而确立了化学1模块电离、离子反应专题的教学论问题并进行了阐述分析。在上述研究的基础上,设计了化学1模块电离、离子反应专题的单元整体教学,并进行了教学实践,取得了较好的教学效果。     

钠在氯气中燃烧实验的改进

指出了现行高中化学教材中钠在氯气中燃烧实验的不足,详细介绍了改进后的实验装置及其实验方法,简化了氯气制备及其实验过程,保障了整个实验在封闭体系内进行,解决了钠在氯气中燃烧实验严重污染环境问题,从而培养了学生的环保意识。     

分析化学实验课程教学大纲的标准化改造与构建

基于工程教育专业认证标准的要求,结合专业课程的特点,对我校制药工程专业的分析化学实验教学大纲进行了标准化改造。标准化的教学大纲更加突出了专业适用性,关联了教学要求与教学内容和考核评定,增加了考核量化指标与课程持续改进的方式,进一步规范了分析化学实验课程的教学。标准教学大纲的构建为实验教学活动提供了更加明确的指导,有利于缩小不同教师教学的差异性,保证了实验教学的质量,为建立可持续完善的工程类实验教学标准体系提供了具体参考。     

非线性多相催化动态模型的理论分析

本文讨论了吸附为非线性的多相催化的动态模型,用特征线方法对该模型进行了分析,求得了流出曲线的解析结果,指出了非线性对多相催化动态测量结果的影响,为速率参数及吸附参数在非线性条件下的动态测定给出了计算公式。     

声发射和激光拉曼研究镍氧化机制中的稀土元素效应

对纯镍及其表面离子注钇样品在1000℃空气中的恒温氧化和循环氧化行为进行了研究。用扫描电镜(SEM)和透射电镜(TEM)对氧化膜的表面形貌及结构进行了观测。研究表明离子注钇极大地提高了金属镍的抗氧化性能。此外,用声发射(AE)技术研究了氧化膜／基体界面上缺陷的分布情况,并用激光拉曼(Raman)谱对注钇引起的膜内应力变化进行了测量。结果表明,离子注钇降低了NiO氧化膜的生长速率,减小了表面NiO的晶粒尺寸,降低了膜内压应力水平。同时,离子注钇还减小了氧化膜／基体界面缺陷的平均尺寸和数目,因此,极大地提高了镍表面NiO氧化膜的粘附性和保护性。     

过氧化氢对8-氨基喹啉衍生物-铜和钴荧光体系的增敏作用及机理研究

本文介绍了新合成的8-氨基喹啉三系列衍生物,系统研究了它们与铜和钴的荧光反应,发现了试剂取代结构对其荧光性能的影响规律,试验了过氧化氢对铜、钴荧光体系的影响,发现了其增敏作用,探讨了增敏机理。     

储氢合金电极的表面修饰研究

利用等离子体技术对AA型MH/Ni电池的储氢合金电极进行了镀覆导电膜层的表面修饰,用XRD及SEM对电极结构进行了表征.极片经过表面修饰的电池,其内阻降低了24％,放电容量有了明显提高,5C (7.5 A) 放电容量提高了200 mA•h,放电平台电压提高了约0.14 V,导电膜层还起到了电极保护层的作用,抑制了合金的粉化,提高了电池的循环稳定性.同时,电池内压显著降低,电池性能有了较大改善.     

无酶葡萄糖传感器

葡萄糖传感器在几十年的发展中取得了重大进展,经历了三代基于酶葡萄糖传感器之后,现已进入第四代无酶葡萄糖传感器的发展阶段.本文从基于酶和无酶两类介绍了不同葡萄糖传感器的测试原理,综述了近年来纳米材料在无酶电化学葡萄糖传感器方面应用的主要研究进展,对不同类别纳米材料的制备方法以及所构建传感器的灵敏度、选择性、检测范围和稳定性等进行了评述,分析了制约无酶葡萄糖传感器商业化应用的主要原因.其中,贵金属纳米材料主要讨论了铂、金和钯;过渡金属纳米材料主要讨论了镍、铜以及其氧化物;双金属纳米材料主要讨论了合金和复合物;碳纳米材料主要讨论了单壁(多壁)碳纳米管和石墨烯.此外,本文也对无酶葡萄糖传感器的发展方向和趋势进行了展望.     

Mechanistic studies of hydrogen-peroxide-mediated anthocyanin oxidation

The oxidation of cyanidin-3-O-glucoside by hydrogen peroxide was investigated in a range of solvents. The reaction products had chemical structures identical to those formed by the reaction of this compound with the alkylperoxyl radical 2,2?-azobis(2,4-dimethyl)valeronitrile. A plausible oxidation mechanism was proposed based on the obtained reaction products, and this mechanism was confirmed by HPLC–MS experiments using ¹⁸O-labeled reagents. Further, the reaction conditions were found to influence both the reaction rate and the products formed during the transformation, which validated the proposed mechanism.     

Study of the reaction between boron trifluoride methanol complex and sodium methoxide

The reaction between boron trifluoride methanol complex and sodium methoxide in methanol solution was investigated using conductivity as the reaction indicator. The reaction conditions were examined and a mechanism of this reaction was proposed. Moreover, proper reaction conditions were proposed for boric acid preparation using this reaction.     

A new mechanism for gas phase ozone–olefin reactions

A new mechanism for gas phase ozone-olefin reactions is proposed. The mechanism involves biradical intermediates which can react in a variety of ways. One of the possible reaction modes corresponds to the Criegie mechanism originally proposed to explain solution ozonolysis reactions and generally also accepted in the past for gas phase reactions. However, an examination of the gas phase data on ozone–olefin reactions and of the thermochemical and kinetic requirements for these reactions indicates that the Criegie reaction mode may be the least important of various other reaction possibilities. Those other reaction possibilities involve intramolecular H abstractions and rearrangements in biradical intermediates. The proposed mechanism provides very reasonable explanations for a number of unusual observations on gas phase ozonolysis. These are the formation of peroxidic bound products, aldehyde and 1,2-dicarbonyl product fluorescences, and unexpected carbonyl product formations.     

氟分子与乙烯反应的直接动力学模拟

Direct dynamics within the framework of DFT was used to study the long-time puzzling mechanism of the reaction between F2 and ethylene. Three types of reactions are widely accepted : F atom elimination reaction, HF elimination reaction and the addition reaction. Several reaction mechanisms have been proposed, but only the radical mechanism can reasonably explain the initial reaction at low temperature. In this article, our calculations support the radical mechanism and the reaction mechanisms of the three reactions, and they are described in detail by trajectory simulation. The reactions in a cryogenic matrix with the reaction mechanism were also discussed.     

低热固相反应的反应机理研究(Ⅰ)——冷融熔机理和冷溶熔机理的模型

本文提出了低热固相反应的冷融熔机理和冷溶熔机理,其中冷融熔机理主要针对于不含结晶水的反应体系,冷溶熔机理主要针对于含结晶水的反应体系,并对低热固相反应动力学提出冷融熔/冷溶熔、扩散、反应、成核、生长的五步机理。两种机理都避开了分子在固相晶格中的扩散,从而对低热固相反应的扩散问题进行了有效的解释,并给出了低热固相反应的热力学和动力学判据。     

Proposed mechanism for diterpene synthases in the formation of phomactatriene and taxadiene

To obtain insight into how the cyclization pathway is controlled, the mechanism of diterpene synthase reactions (the putative phomactatriene synthase and taxadiene synthases) involving the same intermediate was investigated in detail. The mechanism of the initial transformation of GGDP to verticillen-12-yl cation (A+) was proposed based on the labelling pattern of phomactatriene (9a) obtained in the feeding experiments with 13C-labelled acetates. To obtain information on the reaction pathway of A+ to 9a and taxadiene, reactions of verticillol with various acids were conducted. Structural determination of products allowed us to propose a reaction pathway via cations A+, D+, E+, F+ and G+. Identification of hydrocarbons in mycelial extracts of phomactin-producing fungus supported the proposed reaction mechanism. Based on the results of ab initio calculations for highly flexible cation intermediates, a mechanism is proposed.     

A kinetic and mechanistic study on oxidation of Isoniazid drug by alkaline diperiodatocuprate(III) – A free radical intervention

The kinetics of oxidation of isoniazid (INH) by diperiodatocuprate(III) (DPC) in aqueous alkaline medium at a constant ionic strength of 0.05 mol dm⁻³ has been studied spectrophotometrically. The reaction showed first order kinetics both in [DPC] and [INH] and negative less than unit order, both in alkali and periodate concentrations under the experimental conditions. Intervention of free radicals was observed in the reaction. Products of the reaction, isonicotinic acid and copper(II) have no effect on the rate of reaction. Ionic strength and dielectric constant did not affect the rate of reaction. Based on the observed orders and experimental evidences, a mechanism involving the monoperiodatocuprate(III) (MPC) as the reactive oxidant species has been proposed. The main products were identified by I.R, N.M.R. and GC-MS spectral studies. The reaction constants involved in the mechanism were evaluated. Investigations at different temperatures allowed the determination of the activation parameters with respect to the slow step of proposed mechanism. The mechanism proposed and the derived rate laws are consistent with the observed kinetics.     

Kinetics of aquation of chloropentamminecobalt(III) perchlorate in ethylene glycol-water media

Summary The aquation of chloropentamminecobalt(III) ion has been studied in ethylene glycol-water mixtures up to 80% by weight at five temperatures from 35 to 55°C. Specific solvent effects on the reaction rate and mechanism have been investigated and discussed. The validity of our previously proposed equations, correlating the specific reaction rate with the dielectric constant of the medium has been examined. The thermodynamic parameters of activation have been calculated and presented as evidence for the solvation effects and in support of the proposed reaction mechanism.     

钇与2-(4′-氯-2′-膦酰基一苯偶氮)-7-(2′,6′-二溴-4′-氯-一苯偶氮)-1,8-二羟基-3,6-萘二磺酸配位反应动力学研究和机理探讨

用停流分光光度法获得反应的经验速率方程为R=k[y(H_2O~n)~(3+)]·[H_6R]·[H~+]~(-1)。参考Eigen-Tamm机理和测得的动力学参数,拟出了反应的可能机理。     

New reaction of enamines with aryldiazoacetates catalyzed by transition metal complexes

The reaction of aryldiazoacetates with enamines catalyzed by copper and rhodium complexes provided γ-keto esters in good yields. A full investigation of the effects of solvents, catalysts, enamines and aryldiazoacetates on the reaction was carried out. Careful analysis of the crude reaction mixture revealed a substituted enamine as the primary product, which was hydrolyzed over silica gel to give a γ-keto ester as the final product. A reaction mechanism involving nucleophilic addition of an enamine to a metal carbene and subsequent hydrogen transfer was proposed. Chiral dirhodium and copper catalysts were examined and found to provide γ-keto esters with no enantioselectivity. The result could be rationalized based on the proposed reaction mechanism. Attempts to trap the enamine intermediate with several electrophilic reagents were not successful.