四氯化锆四元催化体系中乙烯齐聚反应的动力学研究

研究了四氧化锆作主催化剂的四元催化体系中，乙烯压力、催化剂浓度和温度对乙烯齐聚反应的影响．测定了稳定态下乙烯齐聚反应的宏观动力学方程和表观活化能．     

Trace element determinations in shale oil products by neutron activation

Neutron activation offers some important advantages for the determination of selected trace elements in shale oil products. This paper gives techniques and results of a study of crude shale oil and naphtha, heavy distillate, and wax products of shale oil. The elements determined were Al, As, Au, Br, Ce, Cl, Co, Cr, Fe, Hg, I, K, Mn. Mo, Na, S, Sb, Se, V, and Zn. Some elements (Mn, Na, As) tend to accumulate in heavier fractions, whereas chlorine and iodine are concentrated in the more volatile fractions. The volatility of sulphur compounds in the shale oil products appears to be essentially uniform, with some tendency toward accumulation in distillation residues. The tendency for the trace elements to accumulate in the waxes that precipitated from cooled heavy distillates was very low.     

应用化学"113"人才培养体系的探索

In order to bridge the gap between the supply and the demand of talent cultivation, the existing talent cultivation system of applied chemistry specialty is reformed and a new "113" talent cultivation system is guided by Outcome-Based Education (OBE) education. The advanced engineering education mode is adopted to provide students with an engineering education based on the background environment of the conceptual-design-implementation-operation (CDIO) process. The characteristic "three modernizations" education mechanism, namely, cooperative education, family training and personalized guidance, are implemented. By building a new system of "113" talents training, an engineering talent training environment is formed, which takes the family as a unit, the enterprise as the background, and the project as the carrier. The problem of separating the supply from the demand of talents training for applied chemistry specialty will be fundamentally solved.     

封闭压力酸溶-ICP-MS法分析地质样品中47个元素的评价

对封闭压力酸溶－ICP－MS法同时测定地质样品中47个元素的效果和适用范围进行了实测评价。并对溶样条件进行了优化。实验结果表明，HF－HNO3高温高压酸溶是一种有效的样品分解方法，在所测定的47个元素中，大部分元素如Li,Be,Ti,V,Mn,Co,Ni,Cu,Zn,As,Zr,Nb,Mo,Cd,In,Sn,Sb,Hf,Ta,W,Tl,Pb,Bi等在大多数标样中在三种取样量下都可以得到满意的回收率。而Sc,Cr,Ga,Y,REE,Rb,Cs,Sr,Ba,Th,U等元素在大部分样品中则随取样量减少，回收率上升，在一些样品中，当取样量降至25mg时，可以获得满意的回收率。用王水代替HNO3复溶残渣，利用氯离子的络合作用促进复溶，使许多元素的回收率有了明显的提高。     

计算材料科学中桥域多尺度方法的若干进展

材料科学中存在固有的多尺度特性,桥域多尺度方法是在宏观尺度(如连续介质力学)中引入不同的细微观尺度的计算区域,乃至纳米尺度的分子动力学、量子力学计算区域,将不同尺度的研究方法通过一定的数学模型耦合在一起。该方法既能节约计算成本,又能保证所研究问题的物理特性。本文对多尺度方法的基本概念、跨尺度桥域多尺度方法的发展、基本原理、耦合方法和离散方程进行了讨论,给出了几个应用算例,并在最后进行了总结,展望了今后的可能发展方向。     

Partition coefficients of organic molecules in squalane and water/ethanol mixtures by molecular dynamics simulations

Accurate partition coefficient data of migrants between a polymer and a solvent are of paramount importance for estimating the migration of the migrant over time, including the concentration of the migrant at infinite time in the two solvents. In this article it is shown how this partition coefficient can be estimated for both a small hydrophilic and a hydrophobic organic molecules between squalane (used here to mimic low density poly ethylene) and water/ethanol solutes using thermodynamic integration to calculate the free energy of solvation. Molecular dynamics simulations are performed, using the GROMACS software, by slowly decoupling of firstly the electrostatic and then the Lennard-Jones interactions between molecules in the simulation box. These calculations depend very much on the choice of force field. Two force fields have been tested in this work, the TraPPE-UA (united-atom) and the OPLS-AA (all-atom). The computational cheaper TraPPE-UA force field showed to be more accurate over the whole range of systems compared to the OPLS-AA force field. Moreover, some of the calculations were done with five different water models to investigate the influence of the specific water model on the calculations. It was found that the combination of the TraPPE-UA force field and the TIP4p water model gave the best results. Based on the methodology proposed in this article, it is possible to obtain good partition coefficients only knowing the chemical structure of the molecules in the system.     

X射线荧光在地质材料卤族元素分析中的应用评介

卤族元素氟、氯、溴、碘广泛分布在地圈、水圈和生物圈,它们是矿产资源,也是许多地学研究的信息载体,更与人类生活紧密相关.卤族元素分析是地质分析的重要组成部分,而X射线荧光光谱分析方法在当今的卤族元素分析中占有重要地位.本文收集我国1988年—2020年间X射线荧光光谱分析地质材料氟、氯、溴、碘的文献126篇,在简述卤族元...     

Mechanical wave momentum from the first principles

Axial momentum carried by waves in a uniform waveguide is considered based on the conservation laws and a kind of the causality principle. Specifically, we examine (without resorting to constitutive data) steady-state waves of an arbitrary shape, periodic waves which speed differs from the speed of its form and binary waves carrying self-equilibrated momentum. The approach allows us to represent momentum as a product of the wave mass and the wave speed. The propagating wave mass, positive or negative, is the excess of that in the wave over its initial value. This general representation is valid for mechanical waves of arbitrary nature and intensity. The finite-amplitude longitudinal and periodic transverse waves are examined in more detail. It is shown in particular, that the transverse excitation of a string or an elastic beam results in the binary wave. The closed-form expressions for the drift in these waves functionally reduce to the Stokes’ drift in surface water waves (a half the latter by the value). Besides, based on the general representation an energy–momentum relation is discussed and the physical meaning of the so-called “wave momentum” is clarified.     

Coupled Navier–Stokes—Molecular dynamics simulations using a multi‐physics flow simulation framework

Simulation of nano‐scale channel flows using a coupled Navier–Stokes/Molecular Dynamics (MD) method is presented. The flow cases serve as examples of the application of a multi‐physics computational framework put forward in this work. The framework employs a set of (partially) overlapping sub‐domains in which different levels of physical modelling are used to describe the flow. This way, numerical simulations based on the Navier–Stokes equations can be extended to flows in which the continuum and/or Newtonian flow assumptions break down in regions of the domain, by locally increasing the level of detail in the model. Then, the use of multiple levels of physical modelling can reduce the overall computational cost for a given level of fidelity. The present work describes the structure of a parallel computational framework for such simulations, including details of a Navier–Stokes/MD coupling, the convergence behaviour of coupled simulations as well as the parallel implementation. For the cases considered here, micro‐scale MD problems are constructed to provide viscous stresses for the Navier–Stokes equations. The first problem is the planar Poiseuille flow, for which the viscous fluxes on each cell face in the finite‐volume discretization are evaluated using MD. The second example deals with fully developed three‐dimensional channel flow, with molecular level modelling of the shear stresses in a group of cells in the domain corners. An important aspect in using shear stresses evaluated with MD in Navier–Stokes simulations is the scatter in the data due to the sampling of a finite ensemble over a limited interval. In the coupled simulations, this prevents the convergence of the system in terms of the reduction of the norm of the residual vector of the finite‐volume discretization of the macro‐domain. Solutions to this problem are discussed in the present work, along with an analysis of the effect of number of realizations and sample duration. The averaging of the apparent viscosity for each cell face, i.e. the ratio of the shear stress predicted from MD and the imposed velocity gradient, over a number of macro‐scale time steps is shown to be a simple but effective method to reach a good level of convergence of the coupled system. Finally, the parallel efficiency of the developed method is demonstrated. Copyright © 2009 John Wiley & Sons, Ltd.