Molecular Dynamics Simulations of Thermal Properties of Solid Uranium Dioxide

Molecular dynamics simulations are performed with the recently developed empirical interaction potential by Morelon et al. Thermodynamics properties of solid UO2 that have been assessed include melt point, density, enthalpy, heat capacity, lattice parameter variation with temperature, mean-square-displacement and diffusion coefficients of oxygen ion. The results are compared with the data in literature and it is suggested that the rigid ionic potential provides perfect results below the superionic range. The data showing thermodynamics properties will become unacceptable when the temperature is higher than 2500 K. Compared with the previous empirical potentials, the empirical potential developed by Morelon et al. improves the agreement of these data with the recommend ones.     

Preparation of high performance thin-film polarizers

<正>The optical performance of thin film polarizers is highly sensitive to the layer thicknesses of thin film.The thicknesses of the sensitive layers are optimized in order to gain broader polarizing zone in such case when the total layer thickness does not increase.An automatic layer thickness control system is established,and errors caused by different monitoring methods are analyzed.With this thickness control system,thin-film polarizers with T_p higher than 98%and T_p/T_s higher than 200:1(T_p and T_s are transmissions for p- and s-polarizations,respectively) with the bandwidth of 11 nm are prepared.Using the system allows for optimum repeatability of three successive runs.     

SOFC/GT/ST三重复合动力系统特性研究

本文研究SOFC/GT/ST三重复合动力系统.首先基于Aspen Plus建立了SOFC/GT/ST的性能分析模型,分析了各主要参数对SOFC/GT/ST复合动力系统性能的影响规律.研究结果表明:复合动力系统尽量在高的压力,温度在900℃左右的条件下,有较高系统效率;较高的燃料利用率(Ut)有利于提高系统效率.本文研究...     

(4R,5R)-1,3-二氧戊环-2,2-二苯基-4,5-二-[亚甲基-N,N'-(1-甲基-4-羟基苯甲醛)]的合成及其催化性能

以L-酒石酸和二苯甲酮为原料,经酯化、缩酮、加成、消除、还原和缩合等反应合成了一种新型席夫碱类化合物——(4R,5R)-1,3-二氧戊环-2,2-二苯基-4,5-二-[亚甲基-N,N'-(1-甲基-4-羟基苯甲醛)](4),其结构经1H NMR,13C NMR和LC-MS表征。以二烷基锌对苯甲醛的不对称加成为模板反应,考察了4的不对称催化性能。实验结果表明,4对该反应具有一定的催化效果(ee值52%)。     

Influence of Selective Edge Removal and Refractory Period in a Self-Organized Critical Neuron Model

A simple model for a set of integrate-and-fire neurons based on the weighted network is introduced. By considering the neurobiological phenomenon in brain development and the difference of the synaptic strength, we construct weighted networks develop with link additions and followed by selective edge removal. The network exhibits the small-world and scale-free properties with high network efficiency. The model displays an avalanche activity on a power-law distribution. We investigate the effect of selective edge removal and the neuron refractory period on the self-organized criticality of the system.     

飞秒激光制作铌酸锂光波导的研究

针对Z切割铌酸锂晶体在中心波长为800 nm、重复频率为76 MHz的飞秒脉冲激光下,利用放大倍数为40、数值孔径为0.65的会聚透镜聚焦,研究了扫描速度和扫描次数的变化时刻写光波导结构的影响,分析了波导结构变化的原因,并测试了1×2光波导功分器的通光性能.实验结果表明:在采用横向扫描、聚焦深度为350～400tm、扫...     

Synthesis and Complexation Properties of Novel Chiral Calix[4]-1,3-aza-crown and Calix[4]arene Hydrazone Derivative

<正>Refluxing calix[4]-1,3-substituted benzaldehyde derivative(4) with glycine hydrazide derivative,we obtained a novel calix[4]arene hydrazone derivative(5) via"1+2"condensation in a yield of 78%.In the reaction of compound 4 with L-leucine hydrazide derivative at room temperature,lariat calix[4]-1,3-aza-crown(6) with chiral amino acid group as branched chain was synthesized via"1+1"addition in a yield of 70%.The preliminary extraction experiments suggested that hosting compounds 5 and 6 possessed good complexation abilities forα-amino acids.     

高等学校化学学报第31卷(1～12期)学科分类目次

<正>~~     

亚微米分子筛粒径与性能的关联研究

对实验室合成的不同粒径的NaY分子筛进行了性能研究,表明比表面积、酸量随着粒径的减小而增加,粒径太小的分子筛其稳定性、活性低,不能满足FCC催化剂的使用要求,应用于FCC催化剂的分子筛合适粒径为500nm～800nm.     

Wavelet-fractional Fourier transforms

This paper extends the definition of fractional Fourier transform （FRFT） proposed by Namias V by using other orthonormal bases for L^2（R） instead of Hermite-Gaussian functions. The new orthonormal basis is gained indirectly from multiresolution analysis and orthonormal wavelets. The so defined FRFT is called wavelets-fractional Fourier transform.