R.富兰克林在DNA双螺旋结构发现中的功绩

简介罗萨琳·富兰克林女士的短暂的一生并论述她在DNA双螺旋结构发现中的杰出贡献 .     

Stretching vibration influence of the hydrogen bond on a localized excitation and thermodynamic properties of DNA double helices

The propagation of a localized excitation and the thermodynamic properties in DNA double helices due to stretching vibration of hydrogen bond are discussed. The stretch of the hydrogen bonds is considered as a nonlinear chain with cubic and quartic potential. The analytic solution of the solitary wave is obtained by using the continuum approximation and its stability has been discussed. With the help of the thermodynamic Green function technique, the temperature and anharmonicity effects on the thermodynamic properties of DNA are investigated. The theoretical calculation of the specific heat in DNA at low temperature is consistent with the experimental result. The numerical simulation of the differential-difference equation shows that the solitary wave is pinned by the lattice. It is also pointed out that the conformatioal transitions from B-DNA to A-DNA can occur in the case of asymmetry potential with quartic term.     

��������ѹǿ��Line-tiedŤ�����ȶ��������ʺͱ���������Ӱ��

应用半解析方法,研究了直圆柱位形下等离子体压强P0分别为P0=0、P0=常数和P0=f(r)时Line-tied扭曲不稳定性的增长率和二维径向本征函数的演化规律。结果表明,P0=0和P0=常数时的轴向波数k的范围相同,但P0=常数时的增长率比P0=0时的小。P0=f(r)时的轴向波数k的范围和增长率则都比P0=0时的大,同时磁流体的速度变化也较大。因此,P0=f(r)更接近实际的物理模型(例如日冕的喷射问题)。     

等离子体压强对Line-tied扭曲不稳定性增长率和本征函数的影响

应用半解析方法,研究了直圆柱位形下等离子体压强P0分别为P0=0、P0=常数和P0=f(r)时Line-tied扭曲不稳定性的增长率和二维径向本征函数的演化规律。结果表明,P0=0和P0=常数时的轴向波数k的范围相同,但P0=常数时的增长率比P0=0时的小。P0=f(r)时的轴向波数k的范围和增长率则都比P0=0时的大,同时磁流体的速度变化也较大。因此,P0=f(r)更接近实际的物理模型(例如日冕的喷射问题)。     

The Influence of High Pressure on the Formation of Diketopiperazines And Pyroglutamate in Peptides and Peptide Esters

The effects of pressurization on several short chain peptides were examined. Leucylleucine methyl ester was rapidly degraded under pressure at 60 °C. Results were comparable to the pressure induced degradation of aspartame, meaning that the ester bond is largely high pressure sensitive: The structure of such peptides is consequently modified. Glutamine in model systems underwent cyclization to pyroglutamate under pressure only at conditions unrealistic for industrial purposes: 50 °C, pH 9, and holding times exceeding 30 min. No cyclization of peptides with glutamine at the C-terminus was observed.     

DNA纤维的X射线衍射分析与双螺旋结构的发现

概述了DNA化学结构式确立的过程,介绍了x射线衍射分析的概念、原理和方法,阐述了物理学家威尔金斯和物理化学家富兰克林在用实验事实证明DNA双螺旋结构方面所作出的巨大贡献。     

Quantum size effects on the (0001) surface of double hexagonal close packed americium

Electronic structures of double hexagonal close-packed americium and the (0001) surface have been studied via full-potential all-electron density-functional calculations with a mixed APW+lo/LAPW basis. The electronic and geometric properties of bulk dhcp Am as well as quantum size effects in the surface energies and the work functions of the dhcp Am (0001) ultra thin films up to seven layers have been examined at nonmagnetic, ferromagnetic, and antiferromagnetic configurations with and without spin orbit coupling. The anti-ferromagnetic state including spin-orbit coupling is found to be the ground state of dhcp Am with the 5f electrons primarily localized. Our results show that both magnetic configurations and spin-orbit coupling play important roles in determining the equilibrium lattice constant, the bulk modulus as well as the localized feature of 5f electrons for dhcp Am. Our calculated equilibrium lattice constant and bulk modulus at the ground state are in good agreement with the experimental values respectively. The work function of dhcp Am (0001) 7-layer surface at the ground state is predicted to be 2.90 eV. The surface energy for dhcp Am (0001) semi-infinite surface energy at the ground state is predicted to be 0.84 J/m². Quantum size effects are found to be more pronounced in work functions than in surface energies.     

Nd-四甘醇醛缩苯丙氨酸Schiff碱配合物与DNA相互作用的光谱研究

研究了Nd-四甘醇醛缩苯丙氨酸Schiff碱配合物(NdL)与天然和变性DNA的相互作用.在DNA存在下,测定了NdL的紫外吸收光谱(UV)和荧光激发光谱(FL).利用紫外滴定法,测定了NdL与DNA的结合常数.在20mmol/L Tris-HCl缓冲溶液(pH=7.0),Nd-四甘醇醛缩苯丙氨酸Schiff碱配合物与小牛胸腺DNA的结合常数为4.11×103L/mol,化合物本身的UV和FL峰强度减小.NdL与DNA的作用模式为"静电引力".     

Quantum chemical study on the mechanism of intramolecular cyclization of 2‐benzyloxyphenyl trimethylsilyl ketone to give the benzofuran derivatives

Quantum chemical calculations have been performed to explore the mechanism of intramolecular cyclization of 2‐benzyloxyphenyl trimethylsilyl ketone (acylsilane) to give the benzofuran derivatives stereoselectively. This reaction involves a formation of siloxycarbene intermediate and a C–H bond insertion of siloxycarbene. The comparative studies on three possible insertion of siloxycarbene show that the concerted insertion of siloxycarbene into C–H bond (pathway a), which needs overcoming an energy barrier of 45.1 kcal/mol, is the most unlikely pathway, and the stepwise insertion of siloxycarbene without spin multiplicity change (pathway c) is energetically more favorable than the stepwise insertion of siloxycarbene with spin multiplicity change (pathway b). More importantly, this work can provide an insight into the stereoselectivity in this reaction in atomic molecular level. The formation of siloxycarbene is calculated to be endergonic by 22.9 kcal/mol with an energy barrier of 30.2 kcal/mol, being the rate‐determining step of the whole process. Copyright © 2011 John Wiley & Sons, Ltd.     

Influence of the sequence on the ab initio band structures of single and double stranded DNA models

The solid state physical approach is widely used for the characterization of electronic properties of DNA. In the simplest case the helical symmetry is explicitly utilized with a repeat unit containing only a single nucleotide or nucleotide pair. This model provides a band structure that is easily interpretable and reflects the main characteristic features of the single nucleotide or a nucleotide pair chain, respectively. The chemical variability of the different DNA chains is, however, almost completely neglected in this way. In the present work we have investigated the effect of the different sequences on the band structure of periodic DNA models. For this purpose we have applied the Hartree–Fock crystal orbital method for single and double stranded DNA chains with two different subsequent nucleotides in the repeat unit of former and two different nucleotide pairs in the latter case, respectively. These results are compared to simple helical models with uniform sequences. The valence and conduction bands related to the stacked nucleotide bases of single stranded DNA built up only from guanidine as well as of double stranded DNA built up only from guanidine–cytidine pairs showed special properties different from the other cases. Namely, they had higher conduction and lower valence band positions and this way larger band gaps and smaller widths of these bands. With the introduction of non-uniform guanidine containing sequences band structures became more similar to each other and to the band structures of other sequences without guanidine. The maximal bandwidths of the non-uniform sequences are considerably smaller than in the case of uniform sequences implying smaller charge carrier mobilities both in the conduction and valence bands.     

物理实验开放式教学的探索与实践

介绍了我校在物理实验教学内容、教学方式、教学手段等方面进行的改革探索，总结了开放式实验教学所取得的成效和存在的问题，提出了进一步加大开放实验室的力度的设想。     

铜绿颜料的光谱分析及稳定性研究

在中国颜料使用历史中,铜绿是绿色颜料中使用较为普遍的一种,具有使用地域广、时间长的特点。以碱式氯化铜为主要成分的铜绿为研究对象,探讨了其性质、四种同分异构体的光谱特性及热力学稳定性,并介绍了在彩绘文物中的应用。结果表明,采用拉曼光谱分析可以快速鉴别铜绿四种同分异构体,且对样品仅微损甚至无损。碱式氯化铜四种同分异构体的稳定性大小依次为：斜氯铜矿＞副氯铜矿＞氯铜矿＞羟氯铜矿。对文物样品中的铜绿进行鉴别发现样品中的铜绿多为羟氯铜矿和氯铜矿,属于四种同分异构体中较不稳定的状态。根据奥斯特瓦尔德规则(Ostwald step rule)的相关理论,建议在今后的保护工作中要加强对所属彩绘文物环境等的监控力度,以防止引起彩绘文物发生物理、化学结构的改变。     

Effect of Induced Transition on the Quantum Entanglement and Coherence in Two-Coupled Double Quantum Dot System

Studying quantum properties in solid-state systems is a significant avenue for research. In this scenario, double quantum dots appear as a versatile platform for technological breakthroughs in quantum computation and nanotechnology. This work inspects the thermal entanglement and quantum coherence in two-coupled DODs, where the system is exposed to an external stimulus that induces an electronic transition within each subsystem. The results show that the introduction of external stimulus induces a quantum level crossing that relies upon the Coulomb potential changing the degree of quantum entanglement and coherence of the system. Thus, the quantum properties of the system can be tuned by changing the transition frequency, leading to the enhancement of its quantum properties.     

Model calculations of the energy band structures of double stranded DNA in the presence of water and Na ions

Using the ab initio Hartree-Fock crystal orbital method in its linear combination of atomic orbitals form we have calculated the band structures of poly(-) and poly(-). Here, besides the nucleotide bases, the sugar and phosphate parts of the nucleotide were also taken into account together with their first water shell and Na⁺ ions. We use the notation with a tilde above the abbreviation of a base for the whole nucleotide; for instance poly() means a guanine base with the deoxyribose and PO₄⁻ groups to which it is bound. The obtained band structures were compared with previous single chain calculations as well as with the earlier poly(-) and poly(-) calculation without water but in the presence of counterions. One finds that all the bands of poly(-) and poly(-) are shifted considerably upwards as compared to the previous single chain results (poly(), poly(), poly() and poly()). This effect is explained by the ∼0.2e charge transfer from the sugars of both chains to the nucleotide bases. The fundamental gaps between the nucleotide base-type highest filled and lowest unfilled bands are decreased in both cases by 1-3 eV, because the valence bands are purine-type and the conduction bands pyrimidine-type, respectively, while in the case of single homopolynucleotides they belong to the same base. We also pointed out that the LUMO is mainly Na⁺-like in both investigated cases and several unoccupied bands (belonging to the Na⁺ ions, the phosphate group and the water molecules) can be found between this and the first unoccupied pyrimidine-like empty band.     

磁场和量子点尺寸对方形杂质量子点中电子性质的影响

利用二维有限差分方法,计算了含有H_2~+杂质的方形量子点的基态能和杂质束缚能。讨论了磁场和杂质位置对不同尺寸的量子点中电子基态能量和束缚能的影响,得出了方形量子点系统的量子尺寸效应。     

Vowel Effect on Glottal Parameters and the Magnitude of Jaw Opening

This study investigated the relationship among the magnitude of jaw opening, intrinsic fundamental frequency (F0), and glottal parameters in natural speech. Acoustic, jaw opening, and electroglottographic (EGG) signals were simultaneously recorded. The subjects were 10 healthy men with New Zealand English as their native language. Subjects were asked to repeat a standard nonemphasized sentence in which one of the target vowels (/a/, /e/, /i/, /o/, and /u/) was embedded in various contexts. The glottal parameters F0, open quotient (OQ), and speed quotient (SQ) were measured from the EGG signal. Results of a series of one-way repeated-measures analyses of variance (ANOVA) showed a significant vowel effect on the magnitude of jaw opening [F(4, 24) = 25.512, P < .001], F0 [F(4, 28) = 45.415, P < .001] and speed quotient [F(4, 28) = 5.233, P = .003], but not on the open quotient [F(4, 28) = 0.501, P = .735]. The magnitude of jaw opening was found to be inversely related with F0 (r = -0.624, n = 25, P = .0009). These findings showed that the magnitude of jaw opening was related to F0 and that jaw opening might be a control signal for simulation of long-term F0 variation to achieve a higher degree of naturalness in artificial voice.     

Premicellar and micelle formation behavior of aqueous anionic surfactants in the presence of triphenylmethane dyes: protonation of dye in ion pair micelles

The premicellar and micelle formation behaviors of four cationic triphenylmethane dyes, viz, Pararosaniline (RN), Crystal violet (CV), Ethyl violet (EV), and Malachite green (MG), in aqueous anionic surfactant solutions of sodium dodecyl sulfate (SDS), sodium dodecyl benzene sulfonate (SDBS), and sodium dodecyl sulfonate (SDSN) have been studied by spectral and surface tension measurements. The study was carried out within a pH range where the dyes are stable in their quinoid forms. The dyes have been found to form dye–surfactant ion pairs (DSIPs) with the surfactants, at the surfactant concentrations well below their critical micelle concentration, CMC*. The DSIPs behave like nonionic surfactants and form an air–water interfacial monolayer. The DSIPs have a lower critical micelle concentration (CMC_IP), greater efficiency, and lower effectiveness than the corresponding pure surfactants. As the surfactant concentration is increased below the CMC*, the DSIPs start forming micelles of their own where the dye gets protonated and exists as a protonated dye–surfactant ion pair (PDSIP) in the ion pair micelles. As the concentration of the surfactant exceeds the CMC* of the pure surfactant, the protonation reverses gradually with the dye remaining in the micelles in solubilized form and the DSIPs in the air–water interfacial monolayer are replaced by pure surfactants. The distorted helical isomeric form (isomer B) of the dyes is favored in the PDSIPs. Copyright © 2009 John Wiley & Sons, Ltd.     

含N,O和S的Schiff碱配体与铜（Ⅱ）,锌（Ⅱ）配合物的合成及红外光？…

本文在４０℃下制得了５－氯水杨醛,使其与硫脲缩合合成了一种含Ｎ、Ｏ、Ｓ的新型Ｓｃｈｉｆｆ碱配体,该配体与铜（Ⅱ）,锌（Ⅱ）能形成稳定的配合物,其组成,结构已由元素分析和红外光谱所表征。     

从流场分解角度改进Q矢量分析方法及其在暴雨动力识别中的应用

依据水平风场分解思路,运用调和-余弦算法,准确分解有限区域Q矢量.根据已有的关于Q矢量散度和新发展的Q矢量涡度与天气系统对应关系的研究,运用分解得到的Q矢量旋转分量场和辐散分量场,改进传统Q矢量分析方法中单纯依靠Q矢量水平散度场进行的诊断分析.通过对一次暴雨个例的比较研究表明,在雨带形势和暴雨中心位置的动力识别方面,改进的Q关键词： 矢量分析 调和-余弦算法 暴雨 动力识别