共查询到20条相似文献,搜索用时 78 毫秒
1.
2.
3.
4.
金属-有机配位聚合物在催化性能上的研究进展 总被引:1,自引:0,他引:1
多孔金属-有机配位聚合物(Metal-Organic Coordination Polymers-MOCPs)是一种新型功能材料,可通过其构件分子(金属离子和有机配体分子)的组合对孔穴大小、形状和表面特性进行调控,从而赋于它独特的结构和特性,在催化性能、分子识别、气体吸附、光学、磁性材料等方面具有诱人的发展前景.本文系统介绍了MOCPs在催化性能上的研究进展及其合成途径,并对MOCPs酶模拟体系在传感器方面的应用进行了展望. 相似文献
5.
手性生物矿物广泛存在于自然界中,在生命起源、生物进化、病理学和材料学研究中都扮演着重要的角色。因此,对手性生物矿物产生机制的探究逐渐成为现代热点研究领域。在生物矿化过程中,手性矿化蛋白质分子通过其手性氨基酸残基来实现对生物矿物的调控。本工作从构成手性矿化蛋白质的酸性氨基酸(L-天冬氨酸)、中性氨基酸(L-丙氨酸)和碱性氨基酸(L-赖氨酸)出发,仿生模拟碳酸钙生物矿物生长的手性环境,诱导合成了手性碳酸钙(球霰石)生物矿物。通过光学显微镜、扫描电子显微镜和X射线衍射等表征手段,揭示了各种手性氨基酸在手性碳酸钙的形成过程中所起的作用:酸性氨基酸分子负责球霰石手性结构的调控,碱性氨基酸和中性氨基酸主要负责诱导产生球霰石物相。本研究为手性生物矿物的产生过程构建了新的理论模型,以期促进手性生物材料的合成与发展。 相似文献
6.
超分子凝胶作为一类新型的智能自组装软材料,从分子水平到微纳米水平的组装过程中,手性发挥了重要的作用.一般情况下,手性信号都是直接从分子转换到纳米纤维中,但也有一些有趣的现象,即混合两种对映体可以调控得到不同手性形态的纤维结构,甚至一些本身不具备手性的构筑块同样可以通过外界诱导得到具有手性结构的组装体.对纤维手性自组装机理的研究不仅揭示了分子手性到纤维微纳米手性转换这一重要过程,而且对新型的手性材料和微纳米器件的开发也有启发作用.有关微纳米水平的手性材料在手性识别、不对称催化、生物大分子结晶和无机材料的手性模板剂、生物医用等领域的应用研究也逐渐得到重视.主要综述了近二十年来有关手性超分子凝胶的研究,主要从凝胶因子的手性自组装、手性在分子水平和微纳米水平上的形貌调控和表征方法、超分子凝胶的手性应用几个方面进行概述,并对手性超分子凝胶的应用和研究前景进行了展望. 相似文献
7.
手性膜分离法作为一种新兴的手性分离技术,具有高效、简便、低能耗、可连续操作等特点,在手性分离领域具有巨大的潜力。但近几十年的研究表明,传统手性聚合物材料选择性差、渗透通量低、稳定性差,且难以打破选择性与渗透通量之间的制约关系。这是膜拆分性能无法大幅提高的症结所在,导致膜分离领域长时间处于发展的瓶颈期。近年来,已有许多学者针对这些问题,寻找手性位点更加丰富、稳定性更强、能够提供更多分子通道的新型材料。重点介绍了近5年来基于碳纳米材料、金属有机框架(MOF)、共价有机框架(COF)、改良手性聚合物和一些其他无机材料的新型手性固体膜的合成和应用,并对这些材料的优缺点进行了总结和讨论,以期推动固体膜手性分离技术的进步。另外,还对膜分离机制的研究进展进行了总结,并特别讨论了新材料在手性膜中的作用机制,为进一步改善膜拆分性能提供理论基础。 相似文献
8.
共价有机框架(COFs)是由多齿有机单元通过共价键连接而成的一类新兴的多孔晶体材料。由于COFs材料具有较大的比表面积、较好的结构和化学稳定性等特征,在许多领域表现出优异的应用前景。随着手性科学的不断发展,手性COFs材料应运而生,其结构类型的设计、开发及应用备受研究者们关注。鉴于此,介绍了近年来手性COFs材料的合成策略和合成方法的研究进展,包括后修饰策略、自下而上策略和手性诱导策略,以及基于不同策略设计得到的手性COFs材料结构的类型。此外,简要介绍了手性COFs材料在手性拆分、不对称催化与色谱分析等领域的应用。 相似文献
9.
10.
11.
P. R. Viswanath 《Sadhana》2007,32(1-2):83-92
Separation control has received considerable emphasis in literature both owing to fundamental flow physics and technological
applications. Flow separation generally leads to increased energy losses, instability and so on, and its control is essential
to improve aerodynamic performance. Here a brief review is presented of three broad strategies for separation control: these
include methods that involve energization of the boundary layer upstream of separation, those that involve altering the bubble
flow or dead air zone, and those that may influence the shear layer reattachment directly. Examples from recent research in
our laboratories are reviewed and it is suggested that direct manipulation of the reattachment process could lead to effective
control/management. 相似文献
12.
13.
气体分离膜应用的现状和未来 总被引:7,自引:0,他引:7
考虑了气体分离膜应用和气体传递机理的各种技术.现在商业气体分离膜应用的范围包括:富氮、富氧、氢回收、从天然气中除去酸性气体(CO2和H2S)、天然气脱水和有价值的挥发有机物(VOCs)的回收.讨论了每一个应用中可用膜材料的现状和限度,及有潜在力的若干新膜的应用,如乙烯/乙烷分离和燃料电池. 相似文献
14.
15.
16.
介绍了有机蒸气分离膜的分离原理,并分别介绍了有机蒸气分离膜在石油化工、聚氯乙烯行业中的应用. 相似文献
17.
18.
JÜRGEN TOMAS 《Particulate Science and Technology》2013,31(2):169-187
The separation characteristics of particles’ settling velocity, size, density, and shape are introduced, and the equivalent settling condition for laminar, transition, and turbulent flow are explained. A similarity model of particle transport in a turbulent flow field is briefly discussed. Typical operation principles in separation devices for counter current and cross-flow separation are presented. The separation function, cut point, sharpness, and separation stage utilization coefficient are determined to assess the efficiency for process sequences for multistage turbulent cross-flow separation. Satisfactory to very good results were achieved in the difficult separation of a partially liberated aggregate consisting of hardened cement paste rubble with sharpness from 0.66 to 0.94 at separation stage utilization coefficients of 7 to 87%. Specific mass flow rates of 3 to 16 t/(m2 · h) and mass related energy consumption of 0.2 to 8 kWh/t were obtained. 相似文献
19.
The separation characteristics of particles' settling velocity, size, density, and shape are introduced, and the equivalent settling condition for laminar, transition, and turbulent flow are explained. A similarity model of particle transport in a turbulent flow field is briefly discussed. Typical operation principles in separation devices for counter current and cross-flow separation are presented. The separation function, cut point, sharpness, and separation stage utilization coefficient are determined to assess the efficiency for process sequences for multistage turbulent cross-flow separation. Satisfactory to very good results were achieved in the difficult separation of a partially liberated aggregate consisting of hardened cement paste rubble with sharpness from 0.66 to 0.94 at separation stage utilization coefficients of 7 to 87%. Specific mass flow rates of 3 to 16 t/(m2 · h) and mass related energy consumption of 0.2 to 8 kWh/t were obtained. 相似文献
20.
An airflow‐induced separation method for stacked paper labels is proposed with a stream of compressed air used to jet vertically onto the side of the stacked labels and force constraints applied to the two ends of the labels. Its mechanism is revealed that the viscous force caused by airflow is the main driving force for the initial separation of labels and the vertical force is the main factor for the formation of successive separation channels. Theoretical and experimental analyses are implemented to ensure the effects of airflow velocity, label characteristics, label stress, and other factors on label separation and show that a stable separation gap can be generated with separation efficiency of more than 3600 sheets per minute and reliability of 99.99%. A complete airflow‐induced label separation device is designed, which can be integrated into the existing packaging machine, and the physical feasibility of the stack label separation method is verified by experiments. 相似文献