介电体超晶格

本文评述在介电体超晶格领域中的主要成果,特别是本实验室所做的工作。自1980年以来,我们将超晶格的概念从半导体推广到介电体,制备了周期和准周期介电体超晶格,实现了二次谐波产生、多波长二次谐波产生、三次谐波产生、光学双稳以及超高频超声波产生。 关键词：介电体超晶格; 非线性光学效应; 二次谐波产生; 光学双稳     

从含氟硫酸稀土溶液中萃取铈过程产生第三相的原因

研究了二（2－乙基己基）磷酸（DEHPA）从含氟硫酸稀土溶液中萃取Ce4 过程中生成第三相的组成。运用X荧光光谱法和化学法测定了有机相中析出沉淀物的成分。并分析其原因,发现产生第三相主要是由于有机相对Ce^4 的还原作用造成的。研究了有机相的还原性,进而找出抑制其还原作用,避免第三相生成的方法。     

煤化工工艺技术评述与展望Ⅳ．煤间接液化技术

评述了国内外煤间接液化合成液体燃料开发趋势和工业化状况,从催化剂研制,F－T合成反应器开发,合成油工艺路线,工艺软件开发,工艺集成优化和技术经济分析等方面进行了讨论,指出发展洁净高效煤基合成液体燃料工业过程是解决我国燃油短缺的根本途径,并对我国煤制油工业化开发工作和示范厂建立提出一些建议和展望。     

表面修饰的Ag2S纳米微粒的光学非线性特性

用胶体法制备了表面分别修饰六偏磷酸钠 (HMP)和 2 ,2’ 联吡啶 (BPy)的Ag2 S纳米微粒。通过背向简并四波混频实验装置对它们在单光子非共振区域的三阶光学非线性进行了实验研究 ,分别测量了两种Ag2 S纳米微粒在它们超滤液中三阶非线性极化率 χ( 3 ) 随浓度的变化 ,并拟合得到了两种纳米微粒的三阶非线性极化率。实验结果表明 ,双光子共振增强是实验中非线性极化的主要过程 ,同时实验结果也表明了局域场效应对单光子非共振三阶非线性极化率的增强作用     

六极磁铁的三级Lie映射

用Lie代数方法分析了相对论带电粒子在六极磁铁中的运动,得到在六维相空间中粒子的三级近似轨迹.     

Critical flux in NF of high molar mass polysaccharides and effluents from the paper industry

High molar mass polysaccharides (locust bean gum and karaya gum) and effluents from a mechanical pulp mill and a paper mill were nanofiltered with commercially available nanofiltration (NF) membranes. The effect of the filtration conditions on the flux (critical flux), retention, and the fouling of the membranes was studied. The experiments were conducted by increasing and decreasing the pressure and measuring the flux thus obtained.

The critical flux was observed to increase with increasing flow velocity and decreasing concentration. An increase in pH increased the electrostatic repulsion between the membrane and the dissociated (charged) components in the paper mill effluents. As a result, a higher critical flux was obtained and also the retentions of the charged substances improved. Only a weak form of the critical flux was observed with the mill effluents. The permeate flux deviated from the pure water flux even at the lowest pressure, but increased linearly with pressure until the weak form of the critical flux was exceeded. The small decrease in flux immediately after filtration was started was probably caused by the plugging of the free spaces in the membranes or by the adsorption of foulants onto the membrane surface.

In the filtrations with the high molar mass polysaccharides, a strong form of the critical flux as well as a weak form were observed. The significant irreversible fouling of the most hydrophobic membrane was due to adsorption of the model substances by hydrophobic interaction. A precleaning of the membranes with an alkaline cleaning agent improved the pure water fluxes by up to 30%, but it had only a small effect on the critical or the limiting flux. The pure water fluxes of precleaned membranes after filtration were still higher than the pure water fluxes of the untreated membranes before filtration.     

关于热力学第三定律的能斯特思考

阐明能斯特关于热力学第三定律的思考是大胆的,也是符合逻辑的。     

成都市信息技术产业的计量经济模型

本文针对成都市信息技术产业的实际情况,依据市电子工业局提供的数据建立了成都市信息技术产业的计量经济模型．该模型由８ 个方程组成,包含８ 个内生变量和１２ 个外生变量．根据模型的方程体系,对成都市现有的电子信息产业结构进行分析,揭示了市电子工业总产出的影响因素,提出了该行业结构优化的建议方案,并给出了一个可行的预测方程;分部类排序结果表明成都市信息技术产业化仍停留在分立元器件基础阶段,产业发展水平亟待提高     

整合旅游资源,实现旅游业的新发展

利用主成分因子分析法定量分析浙江省及其5个相邻省份旅游业的综合情况,通过比较找出浙江旅游的优势和劣势,并指出,浙江应加强与相邻各省市旅游资源的整合,加强旅游业的规模经营,实现功能互补,效益最大．     

Implementation of an NDDO/CI/SOS approach for second‐order hyperpolarizabilities

We report the implementation of the sum‐over‐states (SOS) formalism for neglect of diatomic differential overlap (NDDO) Hamiltonians Austin model 1 (AM1), parametric method 3 (PM3), and modified neglect of differential overlap (MNDO) for calculation of third‐order nonlinear optical properties into the program package VAMP and its application to third harmonic generation (THG). Extensive comparisons between THG experimental data and published MOPAC/FF to VAMP/PECI/SOS and AMPAC/FF calculated values were carried out in gas phase and in solvent for a data set of 236 compounds of the general type DπA and conjugated π systems. Great care was taken to derive the global minimum conformers, yielding significant deviations of the geometries derived by the three Hamiltonians. The data set therefore gives an overview of the shortcomings and strengths of the semiempirical methods. Here, the implementations of solvent effects in both semiempirical packages are especially problematic in the case of elongated molecules, so a threshold for molecular globularity had to be defined to eliminate erroneous data. The correlation statistics presented for γ are in acceptable agreement for the whole data set as for all experimentally well‐defined substance classes with scalable correlation slopes smaller than unity. The data become more reliable for large γ, probably due to more precise experimental values. Inclusion of solvent effects raises the polarizabilities of the molecules consistently. These results enable us to qualitatively predict trends for small as well as large second‐order polarizabilities, to derive scaling functions for quantitative predictions, and to calculate experimentally nonaccessible tensor elements of γ. The SOS formalism even allows us to obtain insights into the frequency dependence of second‐order hyperpolarizability effects beyond THG. © 2000 John Wiley & Sons, Inc. Int J Quant Chem 77: 727–760, 2000