A new proposal for the discretization of the Griffin—Wheeler—Hartree—Fock equations

A polynomial expansion is proposed as a new way to discretize the Griffin-Wheeler-Hartree-Fock equations of the Generator Coordinate Hartree-Fock method. The implementation of the polynomial expansion in the Generator Coordinate Hartree-Fock method discretizes the Griffin-Wheeler-Hartree-Fock equations through a numerical mesh which is not equally spaced. This procedure makes the optimization of Gaussian exponents in the Generator Coordinate Hartree-Fock method more flexible and more efficient. The results obtained with the polynomial expansion for atomic Hartree-Fock energies show this technique is very powerful when employed in the design of compact and high accurate Gaussian basis sets used in ab initio non-relativistic (Hartree-Fock) and relativistic (Dirac-Fock) calculations.     

COMPONENT ALLEE EFFECTS AND STAGE‐SPECIFIC PREDATION: A BRIEF INSIGHT INTO CONSERVATION AND BIOLOGICAL CONTROL ISSUES

In this paper, we propose a two‐stage structured population model subject to component Allee effects in fecundity and maturation, and with two disturbances (predation only and harvest and predation) acting on both stages. It is shown that this combination leads to a demographic Allee effect—a characteristic that could be exploited in pest biological control, but on the other hand, it represents a bane in conservation biology. The analysis is performed for disturbances with functional responses type 2 and 3, and the models show that they yield qualitatively similar results. This characteristic is discussed from the species conservation and biological control point of view, together with possible extensions of this work.     

基于多分辨分析的沪深股市相关性分析

为了有效地揭示沪深股市不同交易周期股票交易的相关性,本文采用极大重叠离散小波变换,将上证指数和深圳成指高频收益率分解在不同的交易周期上,对各个周期的收益率采用semi-GPD模型作为其边缘分布分别进行拟合,在此基础上采用Copula函数方法建立同周期收益率的联合分布,度量了沪深两市同周期交易的相关性.实证表明,不同交易周期所表现出的相关性存在明显差异,并且随着交易期的增长,沪深两市非对称结构逐步明显。     

Highly Catalytic Enantioselective Addition of Diethyl Zinc to Aldehydes and Chalcone in the Presence of Chiral Ligands

Catalytic asymmetric carbon-carbon bond formation is one of the most important reactions and have attracted much attention to develop more efficient enantioselective C-C formation methods in organic synthesis. In this field, asymmetric addition of diethylzinc to aldehydes[1] and conjugate addition to enones[2] have drawn special interests and have been greatly developed. Regardless of it, much spaces in these areas still exist, so it needs more extensive and intensive researches for the purpose of as follows: (1) attaching ligands to a polymer for the easy separation of the catalysts so as to be able to allow very efficient recovery and reuse of the catalysts, and the possibility of carrying out the desired transfomation in continuous mode in a flow reactor, etc., (2) searching for novel chiral catalysts with such features as more suitable for more extensive substrates varieties, and more convenient and economical as well as possessing applicable prospect, and so on. Here we report some works in these areas done in our laboratory.     

掺杂和未掺杂氧化锌薄膜的拉曼光谱

利用拉曼光谱分别对不同衬底上,未掺杂和掺杂以及掺杂浓度不同的ZnO薄膜进行了系统的分析研究。其中ZnO薄膜均由溶胶-凝胶法制得,掺杂源为LiCl。测得的拉曼光谱显示,Pt/Ti/SiO2/Si衬底上生长的ZnO薄膜的拉曼特征峰(437cm-1)的强度明显高于SiO2/Si衬底上ZnO薄膜的拉曼特征峰的强度,说明Pt/Ti/SiO2/Si衬底上ZnO的晶化程度比SiO2/Si上ZnO的晶化程度高;但ZnO拉曼特征峰的位置和半高宽并没有发生变化,说明两种衬底上ZnO薄膜中应力大小没有发生变化。掺Li+后,580cm-1处的峰位向高频方向移动,且掺杂浓度越大频移量越大,说明掺杂已经在不同程度上引起了ZnO晶体中自由载流子浓度的变化。此外,还分析了掺Li+未在很大程度上引起ZnO晶格畸变的原因。     

2,2-亚戊基-1,3-二氧六环-4,6-二酮与原甲酸三乙酯和芳香胺的反应

剂,在有机合成中已有一定应用。开展Meldrum's 酸系列化合物的研究,旨在:1.寻找有结构特点的新试剂,2.合成一系列新化合物,3.研究新化合物的应用。本文通过控制反应温度(28～29℃)催化剂用量(比文献用量多近一倍),提高了2,2-亚戊基-1,3-二氧六环-4,6-二酮(PDDO,3)的制备得率(由15%     

Reflection and absorption of light by a quantum well in a strong magnetic field under pulsed irradiation

The interaction between a quantum well with a large number of equidistant excited electron energy levels and light is investigated. It is shown that nonsinusoidal oscillations occur in the transmitted, reflected, and absorbed energy fluxes under exposure of the quantum well to irradiation with light pulses. For long pulses whose length γ _l ^?1 is one order of magnitude longer than the time ?/ΔE (where ΔE is the energy level spacing), the oscillation amplitude is small. In the case of narrow pulses when γ _l ^?1 ≤?/ΔE, the oscillation amplitude is comparable to the flux magnitudes. For very narrow pulses with

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, the decaying echo of exciting pulse should be observed at the time intervals 2π?/ΔE. Symmetric and asymmetric pulses are considered. The theory is applicable to narrow quantum wells in a strong magnetic field when the equidistant levels correspond to electron-hole pairs with different Landau quantum numbers.

     

The role of spatial dispersion of an electromagnetic wave in its penetration through a quantum well

The theory of light penetration through a quantum well in a strong magnetic field perpendicular to the well plane is developed under the conditions where interband transitions occur in the well. The light wavelength is assumed to be comparable to the well width. The relationships for the reflection, absorption, and transmission are derived with due regard for the spatial dispersion of a monochromatic light wave and the difference between the refractive indices of the quantum well and the barrier. The normal incidence of light with respect to the well plane is considered, and one excited level is taken into account. It is demonstrated that the above two factors most strongly affect the reflection, because the reflection from the well boundaries appears in addition to the reflection caused by interband transitions in the quantum well. The most radical changes in the reflection are observed in the case when the reciprocal radiative lifetime of the excited state in the quantum well is short compared to the reciprocal nonradiative lifetime. In the range of large well widths, the applicability of the theory is limited by the existence condition of quantum well levels.     

甘氨酸衍生化β-环糊精键合硅胶液相色谱固定相的合成与评价

 β-环糊精键合硅胶经对甲苯磺酰化后,与甘氨酸反应得到甘氨酸衍生化β-环糊精键合硅胶固定相(GCDS)。考察了GCDS对位置异构体、丹磺酰化氨基酸异构体、苯丙酸类药物等的分离性能,研究了流动相中甲醇浓度、pH以及柱温对色谱保留行为的影响。