基于化学仿真实验平台的师范生微格训练新方法研究

为有效改善高师院校化学专业师范生的微格教学现状,切实提高微格教学质量,通过对微格教学现实困境和化学仿真实验平台优势的分析,提出了基于化学仿真实验平台的师范生微格训练新方法,并以“富集在海水中的元素--氯”为例,介绍了运用该平台进行微格教学的方法与效果。     

MONTE CARLO SIMULATION OF TRIBLOCK COPOLYMER/HOMOPOLYMER BLEND FILMS

1. INTRODUCTION The extensive applications of block copolymer have been studied in detail due to their special molecular architecture and characteristic [1,2]. Recently, many studies including theoretical analysis and experimental techniques have addressed the polymer blend system of diblock copolymer/homopolymer [3~9]. An early investigation presented a quantitative analysis of homopolymer distributions in well-ordered copolymer microdomains through mixing polystyrene (PS) or poly methyl…     

半结晶聚合物注射成型中结晶动力学的数值模拟

对半结晶聚合物注射成型过程及其结晶过程进行偶合模拟,分析了二者的相互影响.具体是在注射成型数值模拟中考虑结晶动力学效应,分别在本构方程、能量方程及材料物性参数方程中引入反映结晶效应的参数;同时在结晶动力学计算中考虑流动诱导效应,从能量的角度提出并使用修正的动力学模型,用材料流动过程的耗散能表征流动对结晶的影响.通过对等规聚丙烯(iPP)和聚对苯二甲酸乙二醇酯(PET)两种半结晶聚合物注射过程模拟结果的分析比较,证实成型过程具有加速结晶的作用.同时,材料的结晶也对注射成型加工过程,尤其是保压与冷却过程的温度场分布有较大的影响.     

A free-energy perturbation method based on Monte Carlo simulations using quantum mechanical calculations (QM/MC/FEP method): application to highly solvent-dependent reactions

This study describes the framework of the quantum mechanical (QM)/Monte Carlo (MC)/free‐energy perturbation (FEP) method, a FEP method based on MC simulations using quantum chemical calculations. Because a series of structures generated by interpolating internal coordinates between transition state and reactant did not produce smooth free‐energy profiles, we used structures from the intrinsic reaction coordinate calculations. This method was first applied to the Diels–Alder reaction between methyl vinyl ketone and cyclopentadiene and produced ΔG values of 20.1 and 21.4 kcal mol^?1 in aqueous and methanol solutions, respectively. They are very consistent with the experimentally observed values. The other two applications were the free‐energy surfaces for the Cope elimination of N,N‐dimethyl‐3‐phenylbutan‐2‐amine oxide in aqueous, dimethyl sulfoxide, and tetrahydrofuran solutions, and the Kemp decarboxylation of 6‐hydroxybenzo‐isoxazole‐3‐carboxylic acid in aqueous, dimethyl sulfoxide, and CH₃CN solutions. The calculated activation free energies differed by less than 1.8 kcal mol^?1 from the experimental values for these reactions. Although we used droplet models for the QM/MC/FEP simulations, the calculated results for three reactions are very close to the experimental data. It was confirmed that most of the interactions between the solute and solvents can be described using small numbers of solvent molecules. This is because a few solvent molecules can produce large portions of the solute–solvent interaction energies at the reaction centers. When we confirmed the dependency on the droplet sizes of solvents, the QM/MC/FEP for a large droplet with 106 water molecules produced a ΔG value similar to the experimental values, as well as that for a small droplet with 34 molecules. © 2010 Wiley Periodicals, Inc. J Comput Chem, 2011     

Molecular Simulation of HER2/neu Degradation by Inhibiting HSP90

Several flavonoids were investigated for the degradation of the HER2/neu (ErbB‐2), while the mechanism is still unknown. A hypothesis was generated here that the inhibition of HER2/neu expression was blocked by heat shock protein 90α (HSP90α) through 1‐benzyl‐3‐(5‐hydroxymethyl‐2‐furyl)indazole (YC‐1) derivatives and flavonoids. In order to ensure the accuracy of the simulated protein structure, the RMSD value between the ligand in crystal structure from PDB and the ligand docking into HSP90α was 1.13 Å. By molecular simulation, the flavonoids and YC‐1 derivatives were employed to dock into HSP90α. The results showed a good correlation between the evaluation scores of the flavonoids/HSP90α complexes and the IC₅₀ of flavonoids‐induced degradation of HER2/neu. The YC‐1 derivatives showed higher score values and lower interaction energies on average. Especially, the CLC107 got the highest rank in Potential of Mean Force (PMF) and Dock Score. Luteolin showed the highest dock score and quercetin had the lowest interaction energy of all flavonoid derivatives. This study investigated that the YC‐1 derivatives and the flavonoids may be potent inhibitors for HSP90α in antitumor strategies.     

Real-time method for the identification and quantification of hydrocarbon pyrolysis products: Part II. Application to transient pyrolysis and validation by numerical simulation

A real-time quantification infra red method has been developed with a gas cell to determine the composition of hydrocarbon pyrolysis products. The aim is to chemically characterise the fuel decomposition in case of regenerative cooling. The method can be extended to a large variety of applications. A transient analysis of the method behaviour is conducted to estimate its capacity to be applied to unsteady conditions (one measure per second), which can be encountered in cooling activity and unsteady processes. A numerical tool called RESPIRE (French acronym for Supersonic Combustion Ramjet Cooling with Endothermic Fuel, Transient Reactor Programming) is used to help in understanding the complex phenomena involved in such a chemical reactor. The validation of transient behaviour with respect to the computations shows negligible time delay (lower than few seconds with gasification rate higher than 60 wt.%) due to residence time in the experimental setup. The quantification accuracy is confirmed to be around 2 mol%. The agreement obtained on gas cell measurements is found to be correct over 10-20 wt.% of gasification rate and very satisfactory over 60 wt.% but this depends on the species. An extension of the method has been developed with a dedicated online cell to be specifically applied to supercritical and multiphase flows. The quantification of the gas phase in the pyrolysis mixture in case of biphasic flow is proposed and validated with an uncertainty around 3 wt.%. The coke formation is monitored as a function of time and its quantification is even tested with 50% of uncertainty after a numerical calibration with respect to simulation.     

基于粗粒化模型对有机溶剂的分子动力学模拟

在基于Boltzmann分布对四种基本构象进行Monte Carlo取样后, 通过与全原子模型的范德华势比较得到了Gay-Berne (GB)参数. 又在对用量化计算得到的分子体系的电势进行电荷、偶极矩和四极矩的拟合后, 得到了电多极展开势(EMP)参数. 利用得到的粗粒化参数, 基于粗粒化模型, 对CHCl₃及四氢呋喃(THF)两种有机溶剂进行了分子动力学模拟(MDS), 并将结果同全原子模拟进行了比较. 计算结果表明用粗粒化模型从整体上能重复全原子模型的模拟结果, 但在某些细节的计算与全原子模型有偏差, 其原因可能是目前工作仅考虑了单位点情况, 为此今后在对具有复杂结构的分子进行粗粒化模拟时还应考虑合理放置及增加相互作用位点.     

软粒子力学性能的模拟研究

运用弹性膜理论结合三角网格动力学模型模拟研究了平行板压缩软粒子的过程, 仔细考察了压缩过程中软粒子的形状变化、应力响应、力学松弛和粘弹行为. 模拟结果与已有的实验基本一致.     

拉伸过程中晶向对银单原子线形成几率影响的分子动力学模拟

采用基于原子镶嵌势函数的分子动力学方法, 模拟了银纳米线沿[100]、[110]和[111]晶向拉伸过程中的空间原子结构和性能. 研究结果表明不同晶向的材料力学性质有显著不同, 屈服应力按照[111]、[110]和[100]依次降低. 从形变位图观察到纳米线在断裂前形成单原子线排列. 由900个分子动力学模拟样本统计得出沿三个晶向形成单原子线的几率, 其中沿[111]晶向形成单原子线的几率明显高于其他两个晶向. 本文从形变机理阐述了单原子线生成几率与晶向的依赖关系.     

葡萄糖水溶液氢键结构和动力分析

利用分子动力学模拟方法研究了不同浓度下葡萄糖水溶液的氢键结构和氢键生存周期. 分析了参与i个氢键(分子内、分子间、所有类型)的葡萄糖分子和水分子的百分比分布. 研究发现存在一个特征数N, 参与N个氢键的分子的比例最高, 当iN时, 参与i个氢键的分子的比例随着浓度的增加而减小. 还分析了不同类型氢键(葡萄糖分子内、葡萄糖分子间、水分子间、葡萄糖分子与水分子间、所有类型)的连续和截断自相关函数, 并计算了对应的氢键生存周期.