Choice of the best alternative in case of a continuous set of states of nature-application of fuzzy numbers

On the basis of a known application of an order weighted averaging operator to the decision making in the case of a discrete set of states of nature, a general approach to the case of a continuous set of states of nature is proposed. The general approach encompasses various types of attitudes of the decision maker, expressed in the form of fuzzy numbers.     

Investigation of KTiOPO4 nanocrystals by means of second-harmonic light emission

The finding of nonlinear nanometric-sized probes is of key importance for the development of nonlinear microscopy in physical as well as biological sciences. We isolate nonlinear KTiOPO4 nanocrystals and study them by second-harmonic generation microscopy （SHGM） and atomic force microscopy （AFM） independently. With both polarization analysis and defocused imaging of the emitted second harmonic field, we extract the Euler angles of the crystalline axes of a single nanocrystal. A balanced coherent optical homodyne detection shows the coherent nature of the nanocrystal nonlinear emission and allows a phase measurement of the emitted second-harmonic field. These features make the KTiOPO4 nanocrystal a good candidate for a vectorial probe of electromagnetic near fields.     

X-ray emission and absorption spectra of Cr(CO)<Subscript>6</Subscript>: A comparison of quantum-chemical and full multiple scattering calculations with experiment

A simple method of forming an energy matrix is suggested for solving the problem on the electronic states of arbitrarily large molecular systems consisting of large separate fragments that are quite stable in their characteristics. It is shown that the appropriate data on fragments can be recorded in a form suitable for storage in databanks. As a result, the determination of the eigenfunctions and energy levels corresponding to the electronic motions is logically similar to the conventional linking technique that forms a molecule from fragments.     

Power law of nucleation rate of folded-chain single crystals of polyethylene

The number-average molecular weight (M _n) dependence of the primary nucleation rate (I) of polyethylene (PE) folded-chain single crystals was studied in the ordered phase. We observed that the M _n dependence of I is mainly controlled by the diffusion process of polymer chains within the interface between a nucleus and the melt and/or within the nucleus. The results show that I decreases with increasing M _n and follows a power law I∝M _n ^−2.3 for the ordered phase. It is named the power law of the nucleation rate. In a previous article we showed that for the disordered phase I∝M _n ⁻¹. In this article, we concluded that I decreases with increasing M _n and follows a universal power law, I∝M _n ^−H for both ordered and disordered phases. The power H depends on the degree of order of the crystalline phase, which is related to the morphology. Received: 13 September 2000 Accepted: 15 November 2000     

中学化学教学中平衡常数的价值和意义的分析

高中《化学反应原理》新增设了化学平衡常数、电离常数、盐的水解常数、溶度积常数4项内容。通过分析得出,化学中的平衡常数是经过长期实验、推演得出的综合数值,它不但蕴含着化学平衡的知识内容、科学的实验方法,同时包含着丰富的人文精神。基于此提出平衡常数的教学可以增强学生的科学本质观,培养学生的科学方法观以及人文精神,利于提高学生的科学素养。     

Variation of the fine-structure constant from the de Sitter invariant special relativity

We discuss the variation of the fine-structure constant,α.There are obvious discrepancies among the results of α-variation from recent Quasi-stellar observation experiments and from the Oklo uranium mine analysis.We use dS Sitter invariant Special Relativity (SRc,R) and Dirac large number hypothesis to discuss this puzzle,and present a possible solution to the disagreement.By means of the observational data and the discussions presented in this paper,we estimate the radius of the Universe in SRc,R which is about ～2(√5)×1011l.y.     

α、β-并三噻吩衍生物分子的二阶非线性光学性质

采用密度泛函理论B3LYP/6-31+g(d)方法对二聚α、β-并三噻吩衍生物的18个分子(a～j2) 进行几何构型优化,对其最优构型采用TD-DFT(TDB3LYP/6-31+g(d))计算电子吸收光谱,用有限场FF方法及自编程序计算二阶非线性光学（NLO）性质。计算结果表明,增加共轭链的含乙烯桥的二聚并三噻吩比不含乙烯桥者,µ(或0)大1.6—5.3倍;在含乙烯桥二聚α、β-并三噻吩分子(母体分子) 末端引入含C=C或C≡C的基团（如-C≡CH与-C=C(CN)2）,比引入强供电子基团（如-N(CH2CH3)2）、单纯吸电子基（如F原子）µ(或0) 更大;尤其是端接-C=C(CN)2基团的二聚α、β-并三噻吩衍生物,其µ（或0）值为104数量级个原子单位(10-29 esu),与母体分子相比µ增大4.8～19.6倍,更有利于改善体系的二阶非线性光学性质,从而可获得良好的非线性光学材料。     

谈“化学微粒观”的内涵及其教育价值

微粒观来自于具体的化学知识,是物质的微观组成和结构、反应机理等微观领域在学习者头脑中的总观性认识,微粒观是最基本的化学观念之一。阐述了化学微粒观的3个内涵,同时论述了化学微粒观的3种教育价值。     

模型本质观进阶框架的理论构建及实证研究

在科学学习中,模型本质观是科学素养的关键组成。本研究基于对已有“模型本质观”研究的分析,建构了“模型本质观”的进阶框架,并对初、高中及大学共计381名学生进行调查。研究表明：学生普遍存在对模型本质认识的迷思概念,在“模型和实物间的关系”维度尤为突出。     

Molecular basis of LFER: theoretical study of polar substituent effect in aliphatic series

The nature of inductive substituent effect on the gas phase acidity of several series of aliphatic carboxylic acids with rigid molecular skeletons was analyzed using the recently proposed quantum chemical approach based on the theory of proton affinity proposed by Longuet‐Higgins. The results of the analysis suggest that the substituent induced variation of the acidity is in all series due to electrostatic field‐effect which in the gas phase can reasonably be characterized by Kirkwood–Westheimer theory. Copyright © 2007 John Wiley & Sons, Ltd.