一例经典高分子化学实验的综合化与创新化

针对目前高分子专业实验教学改革过程中存在的问题,我们进行了一例经典高分子化学实验"醋酸乙烯酯的溶液聚合实验"的综合化与创新化改革。实施情况表明:经典实验综合化与创新化改革有利于学生掌握基本知识;有利于学生认识高分子材料设计、合成、测试各环节之间关系,从整体上认识高分子材料;有利于学生在实验过程中发现经典实验过程中不能出现的实验现象和规律,培养创新思维能力;有利于培养学生的团队协作意识和科学研究基本方法;有利于培养学生的责任感和节能减污意识。

如何通过经典化学实验的优化拓展提升学生的科学探究素养——以中学乙酸乙酯制备实验的优化拓展为例

文章首先分析了经典化学实验优化拓展的价值,然后以乙酸乙酯制备实验的优化拓展为例,探讨了如何通过经典化学实验的优化拓展提升学生的科学探究素养,包括充分挖掘经典实验的价值;引导学生参与经典实验的深度优化;采用项目式实验教学。

经典有机化学实验绿色化改进研究

对经典有机化学实验进行绿色化改进具有重要作用。文章分析了经典有机化学绿色化的改进方向,并通过加强学生实验环保意识、培养学生良好的实验习惯、借助先进技术设计实验、提升学生实验思维能力等措施,提高经典有机化学实验的教学效果,在无公害实验背景下实现环境的有效保护。

分析化学发展史

分析化学始于一些分析检验的实践活动。商品生产和交换的发展 ,促进了分析检验工作。1 6世纪 ,化学反应广泛地应用于湿法分析。 1 8世纪中叶 ,重量分析法使分析化学由单纯的定性分析迈入了定量分析的时代。到了 1 9世纪 ,定性分析趋于完善 ,定量分析的各种方法也相继出现并不断发展。分析化学真正成为一门独立的学科是在 2 0世纪初 ,被称之为经典分析化学。 2 0世纪以来 ,在经典化学不断充实、完善的同时 ,仪器分析也迅猛发展 ,并且在分析化学中占据越来越重要的地位。

Theoretical Study of Reagent Rotational Excitation Effect on the Stereodynamics of H＋LiF→HF＋Li Reaction

The reagent rotational excitation effect on the stereodynamics of H＋LiF→HF＋Li is calcu-lated by means of the quasi-classical trajectory method on the Aguado-Paniagua2-potential energy surface （AP2-PES） constructed by Aguado et al. [J. Chem. Phys. 106, 1013 （1997）]. The angular distributions of vector correlations between products and reactants, P（？r） and P（Φr） are presented. Meanwhile, the four polarization-dependent generalized differential cross sections are computed. The results indicate that the reagent rotational quantum num-bers have impact on the vector properties of the title reaction. In addition, the reaction probability has been calculated as well.

Quasi-Classical Trajectory Study on O＋＋DH（v=0,j=0）→OD＋＋H Reaction at Different Collision Energy

The quasi-classical trajectory calculations O＋＋DH（v=0,j=0）→OD＋＋H reactions on the RODRIGO potential energy surface have been carried out to study the isotope effect on stereo-dynamics at the collision energies of 1.0, 1.5, 2.0, and 2.5 eV. The distributions of dihedral angle P（~r） and the distributions of P（Or） are discussed. Furthermore, the angular distributions of the product rotational vectors in the form of polar plot in θr and φr are calculated. The differential cross section shows interesting phenomenon that the reaction is dominated by the direct reaction mechanism. Reaction probability and reaction cross section are also calculated. The calculations indicate that the stereo-dynamics properties of the title reactions are sensitive to the collision energy.

Theories and Applications of Mixed Quantum-Classical Non-adiabatic Dynamics

Electronically non-adiabatic processes are essential parts of photochemical process, collisions of excited species, electron transfer processes, and quantum information processing. Various non-adiabatic dynamics methods and their numerical implementation have been developed in the last decades. This review summarizes the most significant development of mixed quantum-classical methods and their applications which mainly include the Liouville equa- tion, Ehrenfest mean-field, trajectory surface hopping, and multiple spawning methods. The recently developed quantum trajectory mean-field method that accounts for the decoherence corrections in a parameter-free fashion is discussed in more detail.

General Formalism for Setting Up Unitary Transform Operators from Classical Transforms via IWOP Technique

We present a general formalism for setting up unitary transform operators from classical transforms via the technique of integration within an ordered product of operators, their normally ordered form can be obtained too.

Condition of Prequantization to Two—Dimensional Manifolds with Boundary

The Weil's integrality condition of prequantization is generalized to two-dimensional phase space with boundaries. It is shown that in the prequantization condition a term related to the symplectic potential on the boundary appears. The necessity of the generalized condition is proved by analyzing the isolated singularities of the Hermitian bundle while the sufficiency of the condition is proved via geometric construction on the space of equivalence class.

The rate of convergence of the Lax-Oleinik semigroup-degenerate fixed point case

For the standard Lagrangian in classical mechanics, which is defined as the kinetic energy of the system minus its potential energy, we study the rate of convergence of the corresponding Lax-Oleinik semigroup. Under the assumption that the unique global minimum point of the Lagrangian is a degenerate fixed point, we provide an upper bound estimate of the rate of convergence of the semigroup.