化学氧自救器工作原理的探究活动设计

化学氧自救器是当前应用于安全生产和应急救生的主要呼吸器之一,在剖析化学氧自救器产品结构基础上,分析制氧剂和初期生氧器的成分及其性质,模拟氧烛反应,体现产品生产的实现需要科学、技术、工程等多个学科的整合。     

沸石中阳离子对氮/氧吸附性能影响的研究进展

基于制氧吸附剂在变压吸附空分制氧工业应用的重要性，从沸石分子筛的氮／氧吸附性能方面，介绍了低硅沸石LSX、钙沸石、锂沸石、锂银沸石等的研究进展。讨论了沸石分子筛骨架结构和其中阳离子的种类、位置、数量与其吸附特性的关系，探讨其在变压吸附空分制氧中的应用前景。     

铈基复合氧化物中晶格氧用于甲烷部分氧化制合成气

采用共沉淀法制备了Ce-M-O氧载体（M＝Fe、Mn、Cu）,并进行了XRD表征。研究了Ce-M-O中晶格氧部分氧化甲烷制合成气的反应。考察了再生时间、再生温度对氧载体部分氧化甲烷性能的影响。研究结果表明, Ce-Fe-O固溶体中的晶格氧适于部分氧化甲烷制合成气。在新鲜的Ce Fe O氧载体上存在少量的强氧化物种,导致开始阶段大部分甲烷被完全氧化,然后该氧载体能均匀地释放出具有高选择性的体相晶格氧将甲烷氧化为CO和H2。通过对氧载体再生条件的控制,可以有效提高目标产物的选择性,当再生温度为850℃,再生时间为7min时, 获得了最大的CO（96.68%）和H2（97.56%）选择性,同时H2与CO摩尔比达到2.02。在无气相氧存在下,用Ce-Fe-O中晶格氧实现甲烷部分氧化制合成气的方法是可行的。     

表面活性剂对CeZrYO储氧材料性能的影响

采用表面活性剂聚乙二醇改性共沉淀法制备了铈锆钇储氧材料,并详细考察了表面活性剂的添加方式和添加量对储氧材料性能的影响.采用X射线衍射、氧脉冲吸附、H2程序升温还原和N2吸附技术对储氧材料的晶体结构、储氧性能、还原性能和织构性能进行了表征.结果表明,表面活性剂的添加方式和添加量对储氧材料的性能有重要影响.随着表面活性剂添加量的增加,储氧材料的储氧量先增加后减少,在添加量为50%时达最大值.在表面活性剂添加量相同的情况下,与一次性添加制得的样品相比,分两次添加制得的样品的比表面积和孔体积有所增大,抗老化性能有所提高.一次性添加表面活性剂制得的样品经高温老化后,小于10nm的孔基本消失;而分两次添加表面活性剂制得的样品经高温老化后,仍保持有这些小孔.     

环状和网络状有机硼化合物的研究 Ⅱ.1,2-氧硼杂戊环类化合物的合成与性质

2-烯丙氧基-1,2-氧硼杂戊环(1)的侧链有较大化学活性。(1)可与醇类酯交换制得2-烷氧基-1,2-氧硼杂戊环,如2-正戊氧基-、2-环己氧基-、2-环辛氧基、2-氨基乙氧基-1,2-氧硼杂戊环;与乙二醇反应可制得2,2′-次乙二氧基-双-(1,2-氧硼杂戊环)(6),同样,也可制得1,2-丙二醇和2,3-丁二醇衍生物(7)(8)。(1)与三丁基硼和三烯丙基硼热交换可制得2-正丁基-1,2-氧硼杂戊环和2-烯丙基-1,2-氧硼杂戊环(10)。(10)的侧链活性更大,易与醇、胺类反应制得相应衍生物,如2-正丁氧基-和2-烯丙胺基-1,2-氧硼杂戊环,反应机理可能是烯丙基型重排。(1)与氯化亚砜作用可制得2-氯-1,2-氧硼杂戊环(13),另外还有二个破环、氯转位的副产物,3-氯丙基硼酸二烯丙酯及酐。(6)、(7)、(8)的双环相互作用可能形成网络状结构以及(13)的X-衍射结晶结构正在深入研究中。通过1,2-氧硼杂戊环类侧链的交换反应,合成侧链上具有碳、氮、氧、氯的衍生物,不仅表明侧链的多变性,而且表明环本身有相对稳定性。     

甲烷临氧催化转化制合成气研究进展

作为烃类液化的最重要步骤,从天然气制合成气是近几十年催化科学研究的前沿和热点之一.结合笔者实验室的工作,本文介绍了国内外甲烷临氧催化转化制合成气的研究现状,对甲烷部分氧化、甲烷临氧二氧化碳重整、甲烷临氧水蒸气重整及甲烷-二氧化碳-水-氧气偶合重整进行了阐述和分析,综述了在催化剂体系、反应机理和工艺条件等方面近期取得的研究成果;并对甲烷临氧催化转化制合成气技术今后的研究重点及应用作了展望.     

不同前处理制样方法对钢中氧、氮测定结果的影响

讨论了不同物理和化学制样方法对钢中氧、氮测定结果的影响。试验结果表明,物理制样采用锉刀打磨样品表面后剪切,再用乙醚清洗除去油污;化学制样先用20%盐酸溶液溶解样品表面氧化层,再用滴加了4滴30%过氧化氢的10%草酸溶液浸泡,取出后依次用水、无水乙醇浸洗,风干。用以上两种方法制样,钢标准样品中氧、氮含量测定值与标示值一致。在测定钢中氮含量时,可用乙醚清洗后直接测定,以缩短检测周期和减轻劳动强度。该研究结果可用于指导钢样品中氧、氮含量测定时样品的处理。     

催化分子氧环氧化烯烃的研究进展

环氧化合物是一类十分有用的合成中间体 ,广泛应用于石油化工、精细化工和有机合成 .但至今为止 ,工业上除用分子氧直接氧化乙烯制环氧乙烷外 ,其它所有 C2 以上的环氧化合物还不能用分子氧直接氧化相应的烯烃制得 .国外生产环氧丙烷和环氧氯丙烷的主要方法有卤醇法、Halcon法 ,而国内则以卤醇法为主 .另外 ,过酸法常用于精细产品的合成中 ,以 H2 O2 、Na Cl O等为氧源的环氧化研究 ,近年来也已取得了较大的进展 .卤醇法较早应用于生产 ,但存在严重的设备腐蚀和环境污染问题 ;Halcon法利用 ROOH为氧源 ,有联产品 ,生产过程较复杂 ,基本…     

含氟共聚物与钴卟啉复合膜的制备及促进氧输送性能

研究了甲基丙烯酸八氟戊酯-乙烯基咪唑共聚物与钴卟啉复合膜的制备及钴卟啉与氧络合、促进输送性能.共聚物中的咪唑基与钴卟啉的第五配位点在溶液中络合,制得的复合膜具有快速和可逆的氧结合特性.温度降低,钴卟啉与氧络合的平衡常数增加;膜中的钴卟啉与氧络合平衡常数大于N,N-二甲基甲酰胺(DMF)溶液中的平衡常数.钴卟啉与氧络合和选择性地促进氧的输送使共聚物/钴卟啉复合膜的氧渗透系数和氧/氮选择系数提高.     

氧载体的氧物种直接氧化甲烷制合成气

甲烷部分氧化制合成气由于合成气中n(H2)/n(CO)接近2,可直接用于甲醇合成或烃类F-T合成等后续工业过程而在国内外受到了广泛的关注。利用氧载体的氧物种在无气相氧下直接选择氧化甲烷制合成气是天然气化工利用的新方法,本文介绍了该方法的基本原理、概念工艺和对氧载体的性能要求,对应用于该方法的铈基复合氧化物的掺杂和助剂对选择氧化甲烷性能的影响、钙钛矿氧化物氧载体的氧缺陷、氧物种迁移、结构稳定性及其氧物种氧化甲烷的性能进行了阐述和分析,提出了控制氧载体表面状态是获得高合成气选择性的关键,并对该技术今后的研究重点进行了展望。     

A Monte Carlo method for finding important ligand fragments from receptor data

A simulated annealing method for finding important ligand fragments is described. At a given temperature, ligand fragments are randomly selected and randomly placed within the given receptor cavity, often replacing or forming bonds with existing ligand fragments. For each new ligand fragment combination, the bonded, nonbonded, polarization and solvation energies of the new ligand–receptor system are compared to the previous configuration. Acceptance or rejection of the new system is decided using the Boltzmann distribution , where E is the energy difference between the old and new systems, k is the Boltzmann constant and T is the temperature. Thus, energetically unfavorable fragment switches are sometimes accepted, sacrificing immediate energy gains in the interest of finding a system with minimum energy. By lowering the temperature, the rate of unfavorable switches decreases and energetically favorable combinations become more difficult to change. The process is terminated when the frequency of switches becomes too small. As a test, the method predicted positions and types of important ligand fragments for neuraminidase that were in accord with the known ligand, sialic acid.     

An efficient algorithm for multistate protein design based on FASTER

Most of the methods that have been developed for computational protein design involve the selection of side‐chain conformations in the context of a single, fixed main‐chain structure. In contrast, multistate design (MSD) methods allow sequence selection to be driven by the energetic contributions of multiple structural or chemical states simultaneously. This methodology is expected to be useful when the design target is an ensemble of related states rather than a single structure, or when a protein sequence must assume several distinct conformations to function. MSD can also be used with explicit negative design to suggest sequences with altered structural, binding, or catalytic specificity. We report implementation details of an efficient multistate design optimization algorithm based on FASTER (MSD‐FASTER). We subjected the algorithm to a battery of computational tests and found it to be generally applicable to various multistate design problems; designs with a large number of states and many designed positions are completely feasible. A direct comparison of MSD‐FASTER and multistate design Monte Carlo indicated that MSD‐FASTER discovers low‐energy sequences much more consistently. MSD‐FASTER likely performs better because amino acid substitutions are chosen on an energetic basis rather than randomly, and because multiple substitutions are applied together. Through its greater efficiency, MSD‐FASTER should allow protein designers to test experimentally better‐scoring sequences, and thus accelerate progress in the development of improved scoring functions and models for computational protein design. © 2009 Wiley Periodicals, Inc. J Comput Chem, 2010     

遗传算法与药物分子设计

本文对遗传算法及其近年来在药物设计中的应用进行了较为系统的介绍。遗传算法非常适合解决组合优化问题, 它在柔性分子构象搜寻、药效基团推测、蛋白质结构预测、分子对接、全新药物设计以及组合合成中都具有很大的应用潜力。     

导电高聚物的分子设计问题

本文综述了导电高聚物分子设计的一些实验事实和必需考虑的因素。文章涉及的内容有分子性质与固体性质,共轭长度和链的取向与高电导的关系,对离子和离子交换,材料设计——溶解性、加工性和分子复合材料。     

PRO_LIGAND: An approach to de novo molecular design. 3. A genetic algorithm for structure refinement

Summary Recently, the development of computer programs which permit the de novo design of molecular structures satisfying a set of steric and chemical constraints has become a burgeoning area of research and many operational systems have been reported in the literature. Experience with PRO_LIGAND—the de novo design methodology embodied in our in-house molecular design and simulation system PRO-METHEUS—has suggested that the addition of a genetic algorithm (GA) structure refinement procedure can add value to an already useful tool. Starting with the set of designed molecules as an initial population, the GA can combine features from both high- and low-scoring structures and, over a number of generations, produce individuals of better score than any of the starting structures. This paper describes how we have implemented such a procedure and demonstrates its efficacy in improving two sets of molecules generated by different de novo design projects.     

Automated molecular design: A new fragment-joining algorithm

Summary A popular first step in the problem of structure-based, de novo molecule design is to identify regions where specific functional groups or chemical entities would be expected to interact strongly. When the three-dimensional structure of the receptor is not available, it may be possible to derive a pharmacophore giving the three-dimensional relationships between such chemical groups. The task then is to design synthetically feasible molecules which not only contain the required groups, but which can also position them in the desired relative orientation. One way to do this is to first link the groups using an acyclic chain. We have investigated the application of the tweak algorithm [Shenkin, P.S. et al., Biopolymers, 26 (1987) 2053] for generating families of acyclic linkers. These linking structures can subsequently be braced using a ring-joining algorithm [Leach, A.R. and Lewis, R.A., J. Comput. Chem., 15 (1994) 233], giving rise to an even wider variety of molecular skeletons for further studies.     

Flexible Molecules with Defined Shape—Conformational Design

Chemists have for a long time considered molecules simply in terms of their constitution. The importance of molecular shape was recognized perhaps for the first time by the semio-chemists, who were interested in the interactions of fragrant substances with a receptor. Apart from the case of rigid molecules, our ideas and concepts of molecular shape simply reflect an instantaneous situation, because flexible molecules take advantage of the whole range of conformation that is available to them. Nature frequently utilizes flexible molecules whose conformational space is restricted, in other words, molecules that can adopt only a few preferred conformations. This review discusses some of the principles that nature employs in order to impart a defined shape to flexible molecules. The purposeful application of these principles then allows the conformational design of molecular skeletons. For corrigendum see DOI: 10.1002/anie.199215401 For corrigendum see DOI: 10.1002/anie.199216571     

CAVEAT: A program to facilitate the design of organic molecules

Summary A frequently encountered problem in the design of enzyme inhibitors and other biologically active molecules is the identification of molecular frameworks to serve as templates or linking units that can position functional groups in specific relative orientations. The program CAVEAT was designed to address this problem by searching 3D databases for such molecular fragments. Key innovations introduced in CAVEAT are a focus on relationships between bonds and the provision of automated methods to identify and classify structural frameworks. Performance has been a particular concern in formulating CAVEAT, since it is intended to be used in an interactive manner. The focus in this report is the design and implementation of the principal algorthms and the performance achieved.CAVEAT is available from the Office of Technology Licensing, University of California, Berkeley, CA, and from Molecular Simulations, Inc., Burlington, MA; further information is available from P.A. Bartlett.     

CombiDOCK: Structure-based combinatorial docking and library design

We have developed a strategy for efficiently docking a large combinatorial library into a target receptor. For each scaffold orientation, all potential fragments are attached to the scaffold, their interactions with the receptor are individually scored and factorial combinations of fragments are constructed. To test its effectiveness, this approach is compared to two simple control algorithms. Our method is more efficient than the controls at selecting best scoring molecules and at selecting fragments for the construction of an exhaustive combinatorial library. We also carried out a retrospective analysis of the experimental results of a 10×10×10 exhaustive combinatorial library. An enrichment factor of approximately 4 was found for identifying the compounds in the library that are active at 330 nM.