萃取精馏过程中溶剂的分子设计

提出一种新的分子设计方法,名为分类枚举法。该法中先将基团分成骨架基团和功能基团两类,前者是那些能组成烷烃、芳香烃和环烷烃的基团,后者为其余的基团。然后组合骨架基团,列举出所有烷烃、芳香烃和环烷烃分子,再用功能基团代替它们中相应的骨架基团,从而产生其它分子,而后用基团贡献法,计算每个分子的性质,得到预期的溶剂。由于工业成本限制了溶剂分子内功能基团的种类数,分类枚举法可以避免组合爆炸。另外,本文中还修正了八角规则,以避免不合理的基团组合,提高计算效率。最后,用一个工业实例来说明分类枚举法的实用性。     

基于数据库信息的取代基选择

虚拟组合衍生程序能够快速地根据选定的取代基生成大量的虚拟分子,问题在于选择什么样的取代基,才更有目的地控制衍生分子,使它们与受体的结合有更大的成功保障.通过统计数据库中蛋白质残基及其对应的配体取代基,就可以根据目标受体的残基情况,选择那些统计频率较高的取代基,这样比随机地选择取代基会更有目的性,设计的配体更有可能与蛋白质残基有效地发生作用.因此,这是一种新型的、基于数据库信息的概率式取代基选择方法,简称SSDI.SSDI用统计概率的方式,回答了组合衍生所面l临的选择什么样取代基的问题.     

虚拟组合化学分子库的程序设计、实现与应用

介绍了一个组合化学基本工具程序：虚拟组合化学分子库生成程序(Virtual Combinatorial Library Enumerator，VCLE)。以Accelrys公司Accord开发包为基础用C／C 语言进行开发，支持微软公司Windows系统上和太阳微系统公司的Solaris操作系统。VCLE通过解析通式反应，以通式反应物为模板把实际反应物裁剪为取代基，再把取代基连接到通式产物对应的取代位置上，从而组合出以通式产物为骨架的大量分子结构。作为药物发现研究的方便工具，VCLE既可以运行于桌面系统也可以运行于服务器上。     

基于Topomer CoMFA方法的2-哌嗪基噻唑羟肟酸类化合物的三维定量构效关系研究

组蛋白去乙酰化酶是分子靶向抗肿瘤药物的一个重要靶点,目前大多数组蛋白去乙酰化酶抑制剂都属于羟肟酸类化合物。本实验利用Tripo公司的Sybyl-X软件包,采用Topomer CoMFA方法对2-哌嗪基噻唑类羟肟酸类化合物进行了三维定量构故关系分析(3D-QSAR):首先选择在该系列化合物都含有的哌嗪环与噻唑环之间做切割,生成含有公共骨架的R1基团和R2基团,再利用计算机分别自动叠合R1基团和R2基团,并计算立体场和静电场大小,最后得到了该类化合物作为组蛋白去乙酰化酶抑制剂的3D-QSAR模型,q~2=0.561,r~2=0.870。该模型预测结果良好,可以用于设计新型组蛋白去乙酰化酶抑制剂。     

3-芳氧基-6-氯哒嗪化合物除草活性与结构关系的研究

应用半经验量子化学AM1法获得18种3-芳氧基-6-氯哒嗪化合物的优势构象,再用AM1法和分子图形学技术获得其电子结构参数和几何结构参数,然后采用多元线性回归分析(MLR)和人工神经网络误差反传算法(BP)将这些参数和化合物对油菜的抑制活性相关联.MLR和BP建模的复相关系数(R2)、去一法(LOO)交互检验复相关系数(R2cv)分别为0.840,0.743和0.889,0.733,表明所建市的QSAR模型的稳定性和预测能力良好.结果表明,苯环上应尽量避免大体积取代基的引入,在2号位引入的取代基可稍大些;在苯环2、4、6位引入供电子基团、3位引入吸电子基团可提高化合物的除草活性,所建模型可为哒嗪类除草剂的设计合成提供理论指导.     

结合图论和基团贡献法进行分子设计

提出了一种新的计算机辅助分子设计策略—结合图论和基团贡献法的分子设计方法。提出基团触角数、基团特征因数、分子特征因数的定义和分子结构完整定理使基团组合为分子过程自动完成 ,通过予选基团、限定分子基团数及有机物分类法减小合成问题尺寸。给出了系统的设计方法和设计步骤 ,并编制了相应的计算机程序。通过无毒高温载热剂设计和芳烃与非芳烃分离的萃取精馏溶剂设计 2个实例 ,检验了方法的可靠实用性     

通用基团贡献法自动处理系统（GPAG）

本文介绍了通用基团贡献法自动处理系统GPAG.本工作以建立一个通用系统为目标,提出了一套面向化工常用有机化合物结构、覆盖率高的主基团代码集;发展了相应的主基团解析,子结构匹配;有机分子局部、整体及特殊分子的结构信息提取、加工和化合物自动分类.该系统所提出的有机分子结构计算机表示及处理方法可以广泛地适用于各类基团方法的结构信息特点,因此可以方便地扩充新的基团方法.     

后过渡金属催化剂的分子模拟研究

应用量子化学计算程序ADF考察含有不同有机配体的过渡金属镍配合物对催化乙烯聚合反应的作用，对由于取代基不同造成催化活性不同的相关机理进行验证计算；应用分子动力学计算程序考察催化剂失活难易程度，应用量子化学计算程序ADF考察聚合分子双键位置及支化度的变化情况，计算结果表明当吡叮环配体中有甲基取代时，反应活性降低。当苯环上1，3，5位出现甲基取代时；反应不易发生。当配体上有较强的给电子基团取代时，反应活性增强。     

化学数据库内文字信息处理系统(Ⅱ)—无机化合物、离子及分子化学式自动解析程序系统

本文介绍了自动解析无机化合物,水溶液中离子和分子化学式的程序系统ADF。它与检索程序系统配合使用,对某一体系,只需输入它的组成元素或基团,既可以自动挑出该体系中全部可能存在的物质并求出它们的原子系数矩阵,为ITDB和ATDB中各类计算及库的使用提供了方便。     

汽油辛烷值NIR数据处理与建模仿真

随着当今计算机与各类程序软件的开发使用,化学计量学不断发展,人们可以在近红外光谱区内采集大量的数据,并使用各种有效的统计方法,把近红外光谱技术应用于定性与定量.近红外光谱为分子振动光谱的倍频和组合频谱带,主要是对含氢基团的吸收,包含有绝大多数类型有机物的组成与分子结构的丰富信息.原理是基于不同的基团或同一基团在不同化学...     

硅苯与腈氧化物1,3-偶极环加成反应的理论研究

采用密度泛函理论(DFT)方法在B3LYP/6-311G(d,p)水平研究了硅苯与腈氧化物的1,3-偶极环加成反应的微观机理、势能剖面,考察取代基和四氢呋喃溶剂对反应势能剖面的影响。计算结果表明,所研究反应均以协同但非同步的方式进行,且总是Si-O键先于C-C键形成。硅苯分子中Si原子上的给电子和吸电子取代基均有利于反应的进行,而腈氧化物碳原子上的2,4,6-三甲基苯基取代基在热力学上对反应非常不利。四氢呋喃溶剂对所研究反应的势能剖面影响不大。     

Oriented substituent pharmacophore PRopErtY space (OSPPREYS): a substituent-based calculation that describes combinatorial library products better than the corresponding product-based calculation

Initial combinatorial library designs were based on 2D substituent properties. Subsequently, two important extensions were introduced to improve the approach: use of pharmacophores to introduce 3D information, and performing calculations on the enumerated library products rather than just on the substituents. Unfortunately, practical compromises due to the large number of possible products, the large number of conformations per product, and the explicit dependence on the scaffold limit the application of these extensions in five important ways: (1) to small virtual libraries, (2) to only 3- or 4-point pharmacophores, (3) to inadequate conformational sampling, (4) to simplistic diversity measures, and (5) to requiring a complete new calculation for every new library. The 3D oriented substituent pharmacophores have been developed to overcome these limitations. These add two additional points and corresponding distances to each substituent pharmacophore. This adds little additional computation beyond a normal 3D pharmacophore calculation on the substituents, but recaptures most of the orienting information lost in breaking up the enumerated products into fragments. Two main approximations are still implicitly required: the combinatorial conformer assumption and the template alignment assumption. In turn, however, they are designed to account not just for the 3- and 4-point pharmacophores, but for pharmacophores with up to 9 points in enumerated products with three sites of diversity. Perhaps more importantly, pharmacophore calculations are shown to be very sensitive to conformational sampling. The small number of substituents, plus the small number of rotatable bonds per substituent, permits very thorough conformational sampling. For a rigid scaffold with three diversity sites of 1,000 candidate substituents each, the number of molecules to analyze is reduced by a factor of 10(6), and the number of conformations per molecule is reduced by another 10(4). In addition, the modest number of pairwise substituent similarities permits the creation of a Euclidean property space by MDS. This allows for sophisticated experimental design methods that require coordinates, rather than just the counting of the number of set bits in a library union fingerprint. Finally, oriented substituent calculations are scaffold independent and transferable. They can be stored in a database and need not be repeated for every new library. Thus, there are some approximations in the correspondence between oriented substituent pharmacophore similarities and enumerated product pharmacophore similarities. However, these errors are minor compared to the five advantages that the new method enables: large virtual library sizes, thorough conformational sampling, accounting for 1- to 9-point pharmacophores, creation of a Euclidean property space, and a reusable database of precomputed substituent values.     

Internal architecture design and freeform fabrication of tissue replacement structures

Modeling, design and fabrication of tissue scaffolds with intricate architecture, porosity and pore size for desired tissue properties presents a challenge in tissue engineering. This paper will present the details of our development in the design and fabrication of the interior architecture of scaffolds using a novel design approach. The interior architecture design (IAD) approach seeks to generate layered scaffold freeform fabrication tool path without forming complicated 3D CAD scaffold models. This involves: applying the principle of layered manufacturing to determine the scaffold individual layered process planes and layered contours; defining the 2D characteristic patterns of the scaffold building blocks (unit cells) to form the Interior Scaffold Pattern; and the generating the process tool path for freeform fabrication of these scaffolds with the specified interior architecture. Feasibility studies applying the IAD algorithm to example models with multi-interior architecture and the generation of fabrication planning instructions will also be presented.     

An integrated solution for QoS provision and congestion management in high-performance interconnection networks using deterministic source-based routing

A key element in any system based on several interconnected computing and/or storage nodes is the interconnection network. Currently, one of the main concerns of high-speed interconnection network designers is how to improve network performance while using the minimum number of network resources. In that sense, in this paper we describe an efficient switch architecture suitable for any interconnect technology implementing deterministic source-based routing. This switch architecture uses the same network resources to provide two issues that improve network performance: Congestion Management and QoS support. We also present results to compare the effectiveness of this architecture to those of other proposals typically used to provide these issues in this context. These results have been obtained for synthetic traffic and for traces from parallel benchmarks and video frames. From the results, we can conclude that in any traffic scenario, our proposal is as effective as the previous ones, while requiring fewer resources and thus being much more cost-effective.     

The derivation of a chiral substituent code for secondary alcohols and its application to the prediction of enantioselectivity

A chiral substituent code was proposed based on the features of secondary alcohols, in which a chiral center is attached to two substituents in addition to OH and H substituents. The new chirality code, which was generated by predefining positional information of four substituents attached to stereocenter, was applied to two datasets composed of secondary alcohols as the enantioselective products of asymmetric reactions. In the first dataset, the chemical reaction was catalyzed by a biocatalyst, lipase from Candida rugosa. The catalyst for the second dataset was (−)-diisopinocampheylchloroborane. The structure–enantioselectivity relationship models were constructed using random forests with the chiral substituent code as the input. The resulting models were assessed both in terms of single enantiomers and pairs of enantiomers. Satisfactory results were obtained for both datasets. Although the chiral substituent code was specifically developed for secondary alcohols, it can easily be extended to represent chiral compounds possessing a specific chiral center bonded to two variable substituents.     

支持断点续传的自动升级程序的设计

信息管理系统一般采用下面两种架构:C/S架构和B/S架构。对于需要处理大量数据或实时性要求较高的系统,一般采用C/S架构,但C/S架构的一大缺点是客户端应用程序更新工作量大。针对上面缺点,本文介绍了一种在C/S架构下信息管理系统客户端软件自动升级的实现方法,该更新系统支持断点续传技术。     

支持断点续传的自动升级程序的设计

信息管理系统一般采用下面两种架构：C／S架构和B／S架构。对于需要处理大量数据或实时性要求较高的系统,一般采用C／S架构,但C／S架构的一大缺点是客户端应用程序更新工作量大。针对上面缺点,本文介绍了一种在C／S架构下信息管理系统客户端软件自动升级的实现方法,该更新系统支持断点续传技术。     

Demonstrating the Scalability of a Molecular Dynamics Application on a Petaflops Computer

The IBM Blue Gene/C parallel computer aims to demonstrate the feasibility of a cellular architecture computer with millions of concurrent threads of execution. One of the major challenges in this project is showing that applications can successfully scale to this massive amount of parallelism. In this paper we demonstrate that the simulation of protein folding using classical molecular dynamics falls in this category. Starting from the sequential version of a well known molecular dynamics code, we developed a new parallel implementation that exploited the multiple levels of parallelism present in the Blue Gene/C cellular architecture. We performed both analytical and simulation studies of the behavior of this application when executed on a very large number of threads. As a result, we demonstrate that this class of applications can execute efficiently on a large cellular machine.     

基于Web.sql实现WWW动态访问数据库

本文从ＷＷＷ动态访问关系数据库的角度入手，探讨了现有Ｃ／Ｓ结构的延展－标准的“瘦客户机”结构，实现了基于Ｗｅｂ．ｓｑｌ的ＷＷＷ数据库综合信息查询系统。     

密度泛函理论和从头计算法研究环戊二烯衍生物气态酸度及其取代基效应

用B3LYP／6-311G(2df,p)／／B3LYP／631 G*和MP2／6-311G(d,p)／／B3LYP／6-31 G*方法准确地预测了9个系列的环戊二烯衍生物(R=CN,CF3,CHO,C283,F,SiH3,H,CH3,OH,NH2)的C-H键的酸度。环戊二烯衍生物气态酸度的范围从284.9 kcal／mol (化合物5a)到357.24kcal／mol(化合物7j),分析取代基的电性、数量以及位置的影响得到了9个QSAR方程。这些数据有助于我们设计以及合成一些有机酸,并有助于深刻理解相关反应中环戊二烯衍生物的性质。