OPTICAL-PHONON MODES AND FROHLICH POTENTIAL IN ONE-DIMENSIONAL QUANTUM-WELL WIRES

By extending our microscopic model on optical-phonon modes in quantum wells to one-dimensional (1D) quantum-well wires (QWW), the optical displacements and associated electrostatic potentials of optical-phonon modes in 1D QWW are calculated. The modes can be clearly divided into confined LO bulklike, TO bulklike modes, and extended interfacelike modes provided the bulk phonon dispersion is ignored. The character of each type of mode is illustrated with special attention to the interfacelike modes, which are hybrids of longitudinal- and transverse-optical waves from the corresponding bulk materials. Based on the numerical results, approximate analytical formulas for bulklike modes are presented. As in 2D wells, both the optical displacements and Frohlich potentials for the bulklike modes vanish at the interfaces. The finite dispersion of bulk phonons has a more pronounced effect on the 1D phonon modes because interfacelike modes show mixed characteristics of 2D interface and bulklike modes.

Analysis of the optical confinement factor in semiconductor lasers

We derive formulas for the optical confinement factor Gamma from Maxwell's equations for TE and TM modes in the slab waveguide. The numerical results show that the formulas yield correct mode gain for the modes propagating in the waveguide. We also compare the formulas with the standard definition of Gamma as the ratio of power flow in the active region to the total power flow. The results show that the standard definition will underestimate the difference of optical confinement factors between TE and TM modes, and will underestimate the difference of material gains necessary for polarization insensitive semiconductor laser amplifiers. It is important to use correct optical confinement factors for designing polarization insensitive semiconductor laser amplifiers. For vertical cavity surface-emitting lasers, the numerical results show that Gamma can be defined as the proportion of the product of the refractive index and the squared electric field in the active region. (C) 1996 American Institute of physics.

低极性化合物的电喷雾质谱检测方法及几种中藏药材的活性成分研究

本学位论文首先报道了为解决低极性化合物的电喷雾质谱（ESI-MS）分析难题而建立的一种衍生化分析方法；然后从色谱-质谱联用分析、分离纯化和结构鉴定等方面分别报道了几种中藏药材的活性成分研究。论文由下述六章组成： 第一章报道了盐酸羟胺衍生化方法在电喷雾质谱 (ESI-MS) 分析中的应用。该方法利用盐酸羟胺和羰基成肟的快速反应，建立了针对三萜酮等含酮或醛羰基低极性化合物的ESI-MS 信号增强技术。此方法不仅可应用于增强羰基化合物的ESI-MS 质谱信号，还可检测化合物中羰基的个数以及辨别涉及羰基官能团的同分异构体。此外，通过简单的氧化反应，还可将该方法拓展到三萜醇、甾醇等含羟基的低极性化合物，增强它们的ESI-MS 信号。对比已报道的相关ESI-MS 增强质谱信号的衍生化方法，此方法有经济、实用、快速和简便的显著特点。 第二章是关于野生羌活及其栽培品种化学成分的色谱-质谱联用分析。对不同产地野生羌活生长过程中活性成分的动态变化、野生羌活不同形态部位和人工栽培羌活中的活性成分含量进行了HPLC 定量分析。结果表明主要活性成分羌活醇和异欧前胡素都随生长期存在规律性变化，羌活不同形态部位中的活性成分含量也有明显不同。这些实验结果有些较好地印证了传统中医的用药理论，有些也对羌活的传统使用方法提出了新的建议。 第三章介绍了几种传统中藏药材的色谱-质谱联用及串联质谱分析。通过GC-MS 方法，从藏药材长花党参挥发油中共分离鉴定出45 个化合物；利用HPLC方法测定了该藏药材中的主要化学成分——木犀草素的含量（0.7%）；利用串联质谱技术，对西番莲和射干中的主要成分进行了快速鉴定，从西番莲中鉴定了4个黄酮碳苷；从不同产地的射干和川射干中鉴定了8 个主要异黄酮成分，其中包括一个未见报道的化合物。 第四章的内容为藏药材石莲叶点地梅的活性成分研究。从植物石莲叶点地梅(Androsace integra (Maxim.) Hand.-Mazz.) 乙醇提取物的正丁醇萃取部分共分离和鉴定了6 个化合物，利用MS 和NMR 等现代波谱学技术阐明了它们的结构：其中包括4 个三萜类化合物：分别是androsacin (1)、 ardisiacrispin A (2) 、saxifragifolin A (3) 和20(29)-lupen-3-one (4)；一个神经酰胺：4-羟基-Δ8,9(Z)-鞘氨醇-2'-羟基正二十四碳酸酰胺(5)；一个甾体类化合物：胡萝卜苷(6)。化合物1为新的13,28-epoxy-oleanane 型三萜皂苷，在其结构表征的过程中，采用LC-MS 进行糖分析，获得了值得推广的好结果。通过活性筛选发现化合物1~3 对HepG2肝癌细胞表现出不同程度的抑制活性，其中化合物2 活性最好，其IG50 为1.65μg/mL。 第五章是关于一些传统中藏药材的农药活性筛选。利用Syngenta 公司的活性筛选平台对68 种传统中藏药材醇提物进行了抗菌和除草的生物源农药活性筛选。结果表明所筛选的68 种植物提取物中，共有14 种样品表现出明显的除草/杀虫活性，其中水母雪莲花、松萝和茯神木等植物提取物还具有多种生物活性。活性成分还有待进一步追踪分离、纯化和结构鉴定。 第六章为文献综述，概述了羌活药材的研究进展。对羌活属及药用羌活植物从分类学、本草学、品质评价、人工栽培、化学成分及药理作用等方面进行了文献归纳和总结。 In this dissertation, an electrospray ionization mass spectrometry (ESI-MS) signal enhancement method, as well as the work of bioactive components study, HPLC-MS/MS application, bioassay screening, chromatograph separation and structure identification of the metabolites in several medicinal herbs have been reported. First chapter expounded a rapid, simple ESI-MS sensitivity enhancement method for detecting carbonyl groups in natural products has been developed by using hydroxylamine hydrochloride (NH2OH·HCl) as a derivatization reagent. We use the oxime formed during the derivatization reactions and its Beckmann rearrangement intermediates as a means of detecting the carbonyl groups originally present in these triterpenoids. In comparison with other derivatization methods in the literature, this method is simple, specific and can be used to detect carbonyl groups in triterpenoids which have low polarity and are poorly or non-ionizable. Moreover, it can also be used to detect hydroxyl groups by using the Dess-Martin periodinane (DMP) to convert primary and secondary hydroxyls into carbonyl groups. Chapter 2 reported an HPLC-MS method for analyzing the main bioactive compounds in both wild and cultured Notopterygium incisum. The results indicated that the main bioactive compounds varied through different seasons regularly, and in different commercial parts of this herb the content of these compounds also differed from each other. The quantitative analysis results showed that in the traditional commercial parts, the content of main chemical constitutes in Silkworm Notopterygium, Bamboo Notopterygium and Irregular-nodal Notopterygium are higher than that in Striped Notopterygium. This result is tally with the traditionally concept that the quality of Notopterygium, Bamboo Notopterygium and Irregular-nodal Notopterygium are better than that of Striped Notopterygium, which means that the quality of rhizomes is better than main roots. The chemical constituents of cultured N. incisum is reported for the first time in this dissertation and the analysis results showed some growth curves of chemical constituents in this plant, but still left some questions unanswered. Chapter 3 discussed the GC/LC-MS analysis of the traditional Chinese medicines Codonopsis thalictrifolis, Passiflora incarnate, Belamcanda chinensis and Passiflora incarnate. The main constituent, luteolin was isolated and identified from the traditional Tibet medicine of C. thalictrifolis. The quantitative analysis by HPLC has revealed that the content of luteolin in this herb is 0.7%. GC-MS was employed to analyzed chemical constituents of the essential oil from the flower of C. thalictrifolis. More than 60 peaks were detected and 45 of them were identified by comparing their spectra with that of the standards in the database and literatures. ESI-MS/MS was used to analyze the n-butanol extract of Passiflora incarnate. Based on the information of pseudo molecular ions and fragment ions of the glycosides, four major flavone-C-glycosides have been detected and identified as 7-methoxyluteolin-6-C-β-D-glucopyranoside, vitexin, swertisin and orientin. The isoflavone compounds in theextracts of three samples of B. chinensis collected in Gansu, Sichuan and Hunan, and the extract of Iris tectorum collected in Sichuan were analyzed by using TOF-HRMS and IT-MS. From the extracts of these herbs, a new isoflavone, identified as 5’,5,6,7-tetrahydroxy-3’4’-dimethoxyl isoflavon, and 7 known ones have been identified by analyzing the fragmentation patterns and their molecular formulas given by HRMS and the tandem mass spectrometry acquired by IT-MS. Chapter 4 elucidated the isolation and identification of a new triterpene saponin, androsacin (1), along with five known compounds (2-6) were isolated from the whole plants of Androsace integra (Maxim.) Hand.-Mazz., an herb used in traditional Chinese and Tibetan medicine. The chemical structure of the new compound was established as 3β-O-{β-D-glucopyranosyl-(1→4)-O-β-D-xylopyranosyl-(1→2)-O-β-D-glucopyranosyl-(1→4)-[O-β-D-glucopyranosyl-(1→2)]-α-L-arabinopyranosyl}-16α-hydroxy-13β,28-epoxy-olean-30-al by analyzing its MS, 1D- and 2D-NMR spectra. Compound 2 was cytotoxic toward HepG2 cancer cell with the GI50 value of 1.65 μg/mL. Chapter 5 described the biogenic pesticide activity screening of 68 traditional Chinese and Tibetan medicine extractions. The intention of this study is to explore bioactive natural compounds from these traditional medicinal herbs for biogenic insecticides use. Based on Syngenta’s bioassay, 14 extractions of these traditional medicines showed pesticide activities, and some of them had multi-activities on antibacterial and insecticidal. Chapter 6 is a review on the chemical and bioactivity research progress of Notopterygium incisum and N. forbesii.

基于联合分离原子模型的电离理论

采用微扰静态(PSS)模型近似处理极化和结合能效应,并引入了相对论效应、能量损失效应和库仑偏转效应修正的ECPSSR理论是描述直接库仑电离过程最成功的理论,但对于低能离子入射时,其结果明显低于实验值.采用联合分离原子(USA)模型替代ECPSSR中的PSS模型,考虑分子轨道效应得到了基于USA模型的电离理论——MECUSAR理论.对部分碰撞系统进行了计算,得到的碰撞截面与实验结果基本符合.结合OBKN(Oppenheimer-Brinkman-Kramers formulas of Nikolaev)电子俘获模型,对MECUSAR理论进行了进一步修正,使其能对不同电荷态的入射离子进行计算.

Analytic expressions for alpha particle preformation in heavy nuclei

Experimental alpha decay energies and half-lives are investigated systematically to extract alpha particle preformation in heavy nuclei. Formulas for the preformation factors are proposed that can be used to guide microscopic studies on preformation factors and perform accurate calculations of the alpha decay half-lives. There is little evidence for the existence of an island of long stability of superheavy nuclei.

Dynamics of Vortex-Wave under a Travelling-Wave Modulation

The mecha nism of destabilization is studied for the rotating vortices (scroll waves and spiral waves) in excitable media induced by a parameter modulation in the form of a travelling-wave. It is found that a rigid rotating spiral in the two-dimensional (2D) system undergoes asynchronized drift along a straightline, and a 3D scrolling with its filament closed into a circle can be reoriented only if the direction of wavenumber of a travelling-wave perturbation is parallel to the ring plane. Then, in order to describe the behaviour of the synchronized drift of spiral wave and the reorientation of scrollring, the approximate formulas are given to exhibit qualitative agreements with the observed results.

High precision mass measurement and LPT

A Penning trap, which can measure the atomic masses with the highest precision, is one of the most important facilities in nuclear physics research nowadays. The precision mass data play an important role in the studies of nuclear models, mass formulas, nuclear synthesis processes in the nuclear astrophysics, symmetries of the weak interaction and the conserved vector current (CVC) hypothesis. The status of high precision mass measurement around the world, the basic principle of Penning trap and the basic information about the LPT (Lanzhou Penning Trap) are introduced.

A ionization theory based on united and separated atom model

The direct Coulomb ionization process can be generally well described by the ECPSSR theory, which bases on the perturbed-stationary- state(PSS) and accounts for the energy-loss, Coulomb-deflection, and relativistic effects. But the ECPSSR calculation has significant deviations for heavy projectile at low impinging energies. In this paper we propose a new modified ECPSSR theory, i.e. MECUSAR, in which PSS is replaced by an united and separated atom model, and molecule-orbit effect is considered. The MECUSAR calculations give better agreement with the experimental data at lower impinging energies, and agree with the ECPSSR calculations at high energies. By using OBKN (Oppenheimer-Brinkman-Kramers formulas of Nikolaev) theory to describe the contribution of the electron capture, we further modified the proposed MECUSAR theory, and calculated the target ionization cross sections for different charge states of the projectile.

Microscopic examination of NpNn dominance in the evolution of nuclear structure

The proton-neutron interaction in determining the evolution of nuclear structure has been studied by using the Brillouin-Wigner perturbation expansion. The particle-hole and particle-particle p-n interactions are unifiedly described in the theory. The obtained formulas of level energies and excitation energies scaled in the small- and large-NpNn limits can well explain the linearity of the extracted proton-neutron interaction energies and the attenuation of the 2(1)(+) excitation energies against the valence nucleon product NpNn for five mass regions from A = 100-200.

Alpha-decay for heavy nuclei in the ground and isomeric states

The alpha-decay half-lives of nuclei in the ground states and Isomeric states have been calculated within the WKB approximation and Royer's formulas. The barrier in the quasimolecular shape path is determined within a generalized liquid drop model (GLDM). in which the centrifugal potential energy has been introduced to study the unfavored a-decay The agreement between the calculated results and experimental data indicates the reliability of studying alpha-decay of isomeric states with the generalized liquid drop model We find that their is no significant difference of preformation probability between Isomeric states and the corresponding ground states generally in favored alpha-decay Additionally. we extended Royer's formulas by taking account of the role of centrifugal harrier to study the unfavored alpha-decay, and some predicts oil the a decay half-lives of Isomers are made Finally. the effects of angular momontum transfer and Q(alpha) on alpha-decay half-life have been discussed Crown Copyright (C) 2009 Published by Elsevier B.V. All rights reserved

Evaluation of bond covalency and bond valence in Sr-doped perovskite-type compounds

Formulas for decomposing of complex crystals to a sum of binary crystals are described and applied to the study of bond covalency in La1-xSrxFeO3 (0.0 less than or equal to x less than or equal to 0.9) and Ca1-xSrxMnO3 (0.0 less than or equal to x less than or equal to 0.5). The bond valence is treated by bond-valence sums scheme. The results indicate that, for both compounds, with the increasing doping level, the bond covalency and bond valence show the same trend, namely, larger bond covalency corresponds to higher bond valence. For La1-xSrxFeO3, with the increase of doping level, the bond covalency of La-O, Ca-O decreases in the orthorhombic (0.0 less than or equal to x less than or equal to 0.2) and rhombohedral (0.4 less than or equal to x less than or equal to 0.7) systems, then increases slightly for the cubic (0.8 less than or equal to x less than or equal to 0.9) system, but that of Fe-O increases for all crystal systems. A sharp decrease in bond covalency was observed where the crystal changes from orthorhombic to rhombohedral, while a smooth trend was seen for the rhombohedral-to-cubic transition. On the other hand, for orthorhombic Ca1-xSrxMnO3, the bond covalency of Ca-O, Sr-O, and Mn-O (4-coordinate site) decreases with the increasing doping level, that of Mn-O (2-coordinate site) increases.

Synthesis, characterization and catalytic activity for H2O2 decomposition of tetrabasic tungstovanadophosphate heteropoly rare earth element complexes with Dawson structure

Nine tetrabasic tungstovanadophosphate heteropoly rare earth element complexes with Dawson structure were synthesized. Their general molecular formulas are K15H4[Ln . (P2W16VO61)(2)] . xH(2)O(Ln = La3+, Pr3+, Nd3+, Sm3+, Eu3+, Gd3+, Dy3+, Yb3+). Their structures and properties were investigated by IR, UV, NMR, ESR, XRD, TG-DTA. The results showed that the series of complexes have the same structure as K-16[Ce(P2W17O61)(2)] . 50H(2)O. At the same time, the catalytic activity of the complexes for H2O2-decomposition was also investigated.

Probabilistic distribution of one-phase structure seminvariants for an isomorphous pair of structures: Theoretical basis and initial applications

Given a special type of triplet of reciprocal-lattice vectors in the monoclinic and orthorhombic systems, there exist eight three-phase structure seminvariants (3PSSs) for a pair of isomorphous structures. The first neighborhood of each of these 3PSSs is defined by the six magnitudes and the joint probability distribution of the corresponding six structure factors is derived according to Hauptman's neighborhood principle. This distribution leads to the conditional probability distribution of each of the 3PSSs, assuming as known the six magnitudes in its first neighborhood. The conditional probability distributions can be directly used to yield the reliable estimates (0 or pi) of the one-phase structure seminvariants (1PSSs) in the favorable case that the variances of the distributions happen to be small [Hauptman (1975). Acta Cryst. A31, 680-687]. The relevant parameters in the formulas for the monoclinic and orthorhombic systems are given in a tabular form. The applications suggest that the method is efficient for estimating the 1PSSs with values of 0 or pi.

PROBABILISTIC ESTIMATION OF THE STRUCTURE SEMINVARIANTS IN THE MONOCLINIC AND ORTHORHOMBIC SYSTEMS WHEN ANOMALOUS SCATTERERS ARE PRESENT

The estimate formulas for the two-phase structure seminvariants (TPSSs) in the presence of anomalous scattering are obtained from the estimate of the two-phase structure invariants [Hauptman (1982). Acta Cryst. A38, 632-641; Giacovazzo (1983). Acta Cryst.

AN ALGEBRAIC METHOD TO ESTIMATE GENERAL TYPE OF PHASES OF STRUCTURE FACTORS

The algebraic formulas of 1.5 and 2.5 rank are given for four space groups P2(1), Pn, Pna2(1), P2(1)2(1)2(1). It is better that the results of applying them to estimating general type of phases for four correspondent crystal structures. And a method of transforming algebraic formulas from 1.5(2.5) rank is proposed.