Synthesis of Bisphenols Carrying Long Hydrocarbon Side Chains

Bisphenols containing long aliphatic hydrocarbon side chains were synthesized by the condensation of phenol with aldehyde or ketone in the presence of heteropolyacid. Their structures were characterized by IR, ^1H NMR, ^13C NMR and element analysis. The experiment results show that when heteropolyacid was used as a catalyst, these bisphenols were obtained in high selectivity and high yields.     

Synthesis,Characterization and Reactions of 4‐Hydrazino‐2‐methylpyrimidino[4′5′:4,5]thiazolo[3,2‐a]benzimidazole

4‐Hydrazino‐2‐methylpyrimidino[4′,5′:4,5]thiazolo[3,2‐a]benzimidazole ( 4 ) was obtained from hydrazinolysis of the 4‐chloro derivative 3 with hydrazine hydrate. The hydrazino derivative 4 was further cyclized to the corresponding pyrazole 5 , pyrazolone 6 and 5‐methyl‐1,2,4‐triazolo[1″,5″:3′,4′]pyrimidino[5′,6′:5,4]‐thiazolo[3,2‐a]benzimidazole ( 9 ) and 5‐methy‐1,2,4‐triazolo[4″,3″:3′,4′]pyrimidino[5′,6′:5,4]thiazolo‐[3,2‐a]benzimidazole ( 10 ), respectively. The triazolo derivative 10 was isomerized to the triazolo derivative 9 under a variety of reaction conditions.     

混杂聚合

混杂聚合是指同一体系内有两种或两种以上不同类型的聚合反应同时进行的过程,如自由基聚合与阳离子聚合,自由基聚合与缩聚等。混杂聚合能够在原位形成高分子合金,并有可能得到互穿网络结构（ＩＰＮ）,从而使聚合产物具备较好的综合性能。     

DSMC (direct simulation Monte Carlo) analysis of microchannel flow with gas–liquid boundary

High heat capacity and constant operation temperature make a 2-phase heat remover tool promising for solving high heat dissipation problems in MEMS devices. However, microscale analysis of the flow with the conventional Navier–Stokes equation is inadequate, because the non-continuum effect is important when the characteristic dimension is comparable to the local mean free path. DSMC is a direct, particle-based numerical simulation method that uses no continuum assumption. In this paper, the gas–liquid boundary effects in microchannel flow are studied using this method. Modified DSMC code is used to simulate low-speed flow—under which viscous heating produces no significant temperature change—and MD results are incorporated into the DSMC boundary condition. Steady Couette flow simulation results show that the gas–liquid boundary affects the density distribution and the temperature dependence of the slip velocity. Unsteady simulation results show that mass transfer by diffusion is faster than momentum transfer by collision.     

带形状参数的二次三角多项式Bézier曲线形状分析

对一类二次三角多项式Bézier曲线的形状及其控制多边形之间的关系进行了研究.根据控制多边形边之间的相对位置关系,先通过计算推理得到有关空间二次三角多项式Bézier曲线奇、拐点的一个结论;再利用包络理论和拓扑映射的方法,分别得到平面二次三角多项式Bézier曲线上含有尖点、拐点、重结点和曲线为全局凸、局部凸的充分必要条件,并给出了曲线具有尖点、重结点和拐点的数值例子;最后,讨论了形状参数对形状分区的影响.     

基于傅里叶变换的光纤法布里-珀罗传感器解调研究

从双光束干涉的基本原理出发,分析了高斯分布光源条件下利用傅里叶变换解调光纤法布里-珀罗传感器的原理。针对高斯分布光源特点,提出直接对波长均匀采样得到的光谱数据进行快速傅里叶变换,然后利用传感器腔长与频域中峰值频率之间的关系求解传感器腔长的可行性。在此基础上,采用频谱插值技术提高了系统解调精度,并利用宽带光源和光谱仪等组成的解调系统,对所提出的方法进行了实验验证。结果表明,从实验中测得的数据与理论计算值能较好地吻合。     

高斯光束斜入射非平行法布里-珀罗干涉仪后的透射光强分布

基于多光束干涉原理,推导出了高斯光束斜入射非平行法布里-珀罗干涉仪射后的透射光强表达式,在此基础上,着重研究了高斯光束入射角的大小以及法布里-珀罗干涉仪两反射端面的不平行度对透射光强分布的影响。研究结果表明：入射角的大小和干涉仪的不平行度对透射光的强度分布、峰值强度的大小和峰值强度的位置有很大的影响;在入射高斯光束具有较小的腰斑半径或法布里-珀罗干涉仪的两端面的反射率较大时,必须考虑高斯光束沿传输轴线的衍射效应;楔角为负的非平行法布里珀罗出射光斑的光强在“反跳”处急剧下降到零,可利用这一特点对距离进行精确测量。     

An investigation of thermodynamic states during high-pressure fuel injection using equilibrium thermodynamics

A numerical investigation of mixing processes between an injected fuel (an n-alkane) and a chamber inert gas (nitrogen) was carried out for high-pressure fuel injection. The objective is to determine conditions for the coexistence of both liquid and gas phases under the typical ambient conditions encountered in diesel engines. A phenomenological investigation was built by coupling phase stability analysis with the energy conservation equation. Phase changes (including separation and combination) are predicted to occur so as to yield the lowest Gibbs free energy. It is also shown that predicted states without considering phase transitions can be very different from the corresponding thermodynamically correct states. By comparing four n-alkane/nitrogen mixtures it is shown that the lower limit of the two-phase region occurs at similar temperatures. However, heavy n-alkane/nitrogen mixtures have a larger upper limit, and phase separation occurs at higher temperatures. The present model predicts the existence of multiple phases locally in the dense spray jet under high temperature and pressure ambient conditions due to the significant reduction of the mixture temperature caused by vaporization and cooling.     

密度泛函活性理论中的Rényi熵, Tsallis熵和Onicescu信息能

根据密度泛函理论,分子的电子密度确定了该体系基态下的所有性质,其中包括结构和反应活性.如何运用电子密度泛函有效地预测分子反应活性仍然是一个有待解决的难题.密度泛函活性理论(DFRT)倾力打造这样一个理论和概念架构,使得运用电子密度以及相关变量准确地预测分子的反应特性成为可能.信息理论方法的香农熵和费舍尔信息就是这样的密度泛函,研究表明,它们均可作为反应活性的有效描述符.本文将在DFRT框架中介绍和引进三个密切相关的描述符, Rényi熵、Tsallis熵和Onicescu信息能.我们准确地计算了它们在一些中性原子和分子中的数值并讨论了它们随电子数量和电子总能量的变化规律.此外,以第二阶Onicescu信息能为例,在分子和分子中的原子两个层面上,系统地考察了其随乙烷二面角旋转的变化模式.这些新慨念的引入将为我们深入洞察和预测分子的结构和反应活性提供额外的描述工具.     

A Grand Canonical Monte Carlo Study of Adsorption and Capillary Phenomena in Nanopores of Various Morphologies and Topologies: Testing the BET and BJH Characterization Methods

We report a Grand Canonical Monte Carlo simulation study of Ar adsorption at 77 K in silica nanopores having various morphologies/topologies. Both the morphological and topological disorders are shown to significantly affect the capillary condensation phenomenon. In the case of an ellipsoidal pore, we observe that the filling mechanism is similar to that of a cylindrical pore having the same section area but with a lower condensation pressure. We show that the adsorption/desorption hysteresis loop is asymmetrical for the pore with constrictions while it is symmetrical for the regular cylindrical pore. Moreover, the Ar adsorption isotherm for the constricted pore reproduces the main features of that for the fully disordered Vycor‐like porous matrix. The results for the different pore geometries (having no direct interface with the gas reservoir) indicate that the desorption occurs through cavitation at a pressure driven by the smallest void size. We also consider the validity of the BET and BJH methods for the different porous matrices. Except for the Vycor‐like matrix, the BET surface assessed from Ar adsorption isotherm at 77 K always significantly overestimates the intrinsic surface of the pore (even for a planar surface). The disagreement between the BET surface and the geometrical surface is found to increase as the confinement increases (cylindrical pore) and/or the shape of the pore becomes asymmetrical (ellipsoidal pore). Interestingly, the best agreement between the BET and the geometrical surface is found in the case of the pore with a constriction, i.e. a system that exhibits a surface with both negative and positive curvature regions. This idea is supported by the results for the Vycor‐like matrix, which has a distorted surface (many negative curvature regions combined with positive curvature regions): for this disordered porous matrix, the BET surface is found to underestimate the intrinsic surface. Finally, we show that the pore size determined using the BJH method always underestimates the pore size, in agreement with previous experimental and simulation studies.