158 A Ge V p-Pb Pb-Pb碰撞中的单奇异和多奇异粒子产生

用描写相对论性核 核碰撞的LUCIAE模型及相应的MonteCarlo事例产生器分析了WA97最近发表的 1 5 8AGeVp Pb和Pb Pb碰撞中单奇异粒子 (Λ ,Λ)和多奇异粒子 (Ξ-,Ξ-,Ω-,Ω-)的多重数和横质量分布 .由于LUCIAE模型包含了弦碎裂微观过程中奇异夸克压低因子随碰撞体系的能量、中心度和质量的增大而增大 ,以及由它导致的相对论性核 核碰撞宏观过程中奇异粒子产额随上述三因素之增而增的物理机制 ;LUCIAE模型计算结果能较好描写WA97实验所揭示的相对论性核 核碰撞中奇异粒子产额随中心度之增而增和奇异粒子增强随奇异夸克数之增而增的实验事实 ,以及单奇异和多奇异粒子的横质量分布 .     

分子内结构环境对解离能的影响

为了理解化学键的这一结构效应, 本文对具有相同化学键而分子内结构环境不同的系列分子进行了计算研究, 讨论了化学键结构环境对解离能的影响.     

Active site pressurization: a new tool for structure-guided drug design and other studies of protein flexibility

We present a new molecular dynamics methodology to assist in structure-based drug design and other studies that seek to predict protein deformability. Termed Active Site Pressurization (ASP), the new methodology simply injects a resin into the ligand binding-site of a protein during the course of a molecular dynamics simulation such that novel, energetically reasonable protein conformations are generated in an unbiased way that may be better representations of the ligand binding conformation than are currently available. Here we apply two different versions of the ASP methodology to three proteins, cytochrome P450cam, PcrA helicase, and glycogen synthase kinase 3beta (GSK3beta), and show that the method is capable of inducing significant conformational changes when compared to the X-ray crystal structures. Application of the ASP methodology therefore provides a view of binding site flexibility that is a rich source of data for inclusion in a variety of further investigations, including high-throughput virtual screening, lead hopping, revealing alternative modes of deformation, and revealing hidden exit and entrance tunnels.     

The inhibitory effects of vinylphosphonate-linked thymidine dimers on the unidirectional translocation of PcrA helicase along DNA: a molecular modelling study

The PcrA DNA helicases are important bacterial enzymes and quintessential examples of molecular motors. Through conformational changes caused by ATP hydrolysis, they move along the template double helix, breaking the hydrogen bonds holding the two strands together, and separating the template chains so that the genetic information can be accessed. The flexibility of the DNA backbone is essential for the unidirectional translocation of PcrA. A modified DNA substrate with reduced backbone rotational flexibility (via an incorporated vinylphosphonate linkage) has previously been designed and tested as a helicase substrate. The results show that a single modification on the backbone is sufficient to inhibit the activity of PcrA. In this paper a range of molecular simulation methods have been applied to examine the structural origins of this inhibitory effect, as it tests our theories of the mechanism of action of this motor. We observe that the chemical modification has different effects on the energetics of DNA translocation through the protein as it reaches different sub-sites.     

Macroscopic Lyapunov functions for separable stochastic neural networks with detailed balance

We derive macroscopic Lyapunov functions for large, long-range, Ising-spin neural networks with separable symmetric interactions, which evolve in time according to local field alignment. We generalize existing constructions, which correspond todeterministic (zero-temperature) evolution and to specific choices of the interaction structure, to the case ofstochastic evolution and arbitrary separable interaction matrices, for both parallel and sequential spin updating. We find a direct relation between the form of the Lyapunov functions (which describe dynamical processes) and the saddle-point integration that results from performing equilibrium statistical mechanical studies of the present type of model.     

网络上两类物资联合最大流问题的极流特征

当网络上(诸如交通网络、通讯网络)有多种不同物资或信息同时分别从相应的发点输送到相应的收点,要求每条线路上各类物资或信息的输送量总和不超过线路的容量时,寻求所有物资的最大输送量的问题,就是所谓网络多种物资的最大流问题,这个问题在生产实际和理论上都有着重要的意义,1963年T.C.Hu提出了求两类物资联合最大流的标号方法,但是为了保证有限步达到最大流,要求边的容量是偶数。 本文是文献[3]的继续,用图论的语言描述了两类物资最大流问题极流的特征,并对标号方法作了一点修改,使得有限步得到最大流,或者在某一步得到极流后,保证以后的迭代是从极流到极流.这样因极流的个数是有限的,并且最大流总可以在极流上达到,从而保证了有限步内得到所要求的最大流,无须对边的容量作任何限制, 本文所提的算法是使图形特征很强的标号算法和线性规划的极点迭代结合起来,这就使得有可能把这种方法,推广到更大的一类问题中,例如,研究容量的改变对最大流量的影响。     

分子束研究GaAs和InP与氯的激光化学反应动态学

本文采用CW超声分子束和时间分辨质谱技术,研究了在紫外和可见(355nm和560nm)脉冲激光辐照下GaAs(100)和InP(100)表面与氯的激光化学反应动态学。由质谱和飞行时间谱测得反应的主要产物为GaCl_x和InCl_x(x=1,2),研究了激光波长和能量密度对产物飞行时间谱的影响,首次发现提高入射Cl₂分子的平动能对上述激光诱导气-固相反应有明显的增强作用。     

A Study of Synthesis, Immobilization and Catalytic Capability of Metalloporphyrin

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Antitumor benzothiazoles. Frontier molecular orbital analysis predicts bioactivation of 2-(4-aminophenyl)benzothiazoles to reactive intermediates by cytochrome P4501A1

The antitumor and metabolic activities of 2-(4-aminophenyl)benzothiazoles and their fluorinated analogues cannot be explained or predicted by conventional chemical means. Their mode of anti-cancer action involves metabolism of the benzothiazoles to an as yet unidentified reactive species. This species then forms DNA adducts which provoke cell death. The electronic structures and possible intermediates of these compounds have been computed quantum mechanically. The counter-intuitive patterns of metabolism can only be explained by considering the active intermediate to be a nitrenium ion. The distribution of the highest occupied molecular orbital for the nitrenium species derived from each fluorinated analogue correlates perfectly with the production, or otherwise, of an exportable metabolite. Further related compounds have been analyzed by this method and the predictions of their metabolism have subsequently been verified experimentally.