Modular design of icosahedral metal clusters

The concept of crystalline module, that is, an unambiguously isolated, repeated quasi-molecular element, is introduced. This concept is more general than the concept of crystal lattice. The generalized modular approach allows extension of the methods and principles of crystallography to quasi-crystals, clusters, amorphous solids, and periodic biological structures. Principles of construction of aperiodic, nonequilibrium regular modular structures are formulated. Limitations on the size of icosahedral clusters are due to the presence of spherical shells with non-Euclidean tetrahedral tiling in their structure. A parametric relationship between the structures of icosahedral fullerenes and metal clusters of the Chini series was found.     

A New Chemo‐Enzymatic Route to Side‐Chain Liquid‐Crystalline Polymers: The Synthesis and Polymerization of 6‐(4‐Methoxybiphenyl‐4′‐oxy)hexyl Vinyl Hexanedioate

A novel synthetic method combining chemo and enzymatic synthesis strategies was employed to prepare a vinyl acetate type monomer, 6‐(4‐methoxybiphenyl‐4′‐oxy)hexyl vinyl hexanedioate (VA‐LC). Homo‐ and copolymers of VA‐LC with maleic anhydride (MAn) were prepared by conventional free radical polymerization using 2,2′‐azobisisobutyronitrile (AIBN) and 1,1′‐azobis (cyclohexane carbonitrile) (AHCN) as an initiator at 95 and 60 °C, respectively. The thermal properties of the generated polymeric material were investigated by differential scanning calorimetry (DSC), and the optical texture was inspected by polarizing optical microscopy (POM). While the monomer VA‐LC does not exhibit liquid‐crystalline properties, poly(VA‐LC), and the alternating copolymer of VA‐LC with maleic anhydride both displayed such properties.

     

地铁沿线建筑内噪声多维度感受影响机制

随着城市铁路系统的快速发展,铁路沿线建筑内人群对地铁运行产生噪声的抱怨逐渐增多,为控制室内地铁噪声对人群所产生的负面影响,有必要对地铁噪声产生的多维度负面情绪进行评估。采集了79名受试者对建筑内地铁噪声的多维度负面感受(压抑感,不舒适度和不满意度),基于偏最小二乘法分析了主客观影响因素对多维度负面感受的作用机制,并比较了多维度负面感受在反映地铁噪声影响上的差异。结果表明,多维度负面感受主要取决于主观响度和声学参数,活动干扰度、地铁噪声的敏感度、厌烦度和适应性的影响明显更弱;3个多维度负面感受中,相比于压抑感,不舒适度和不满意度受主观响度的影响轻微更显著,在相同的主观响度感受下,不满意度等级最高。 该文可以为地铁沿线建筑物内噪声负面感受的评价和改善提供参考。     

不同晶形纳米碳酸钙的制备及其表面改性研究进展

本文综述了不同晶形纳米碳酸钙的制备方法、纳米碳酸钙表面改性技术的研究现状以及表面改性方法,分析了目前纳米碳酸钙制备及表面改性技术存在的问题,并对其发展前景作了展望.     

Adoption of Common Schemes for Single and Sequential Extractions of Trace Metal in Soils and Sediments

Abstract

The various methods for determining the mode of occurrence of trace metals in sediments and soils have a long history which dates back to the determinations of the availability of metals for plant nutrition performed earlier. Various methods have been developed in the 70′s and 80′s dealing with both single and sequential extraction schemes. Although some schemes received wide acceptance, none of them developed into a commonly accepted procedure. As a result, the information obtained was site-specific and the interpretation of the results scientist-specific. The workshop on single and sequential extraction in sediments and soils held at Sitges     

Twin liquid crystals and segmented thermotropic polyesters containing azobenzene—effect of spacer length on LC properties

We report systematic studies on a homologous series of twin liquid crystalline (LC) molecules based on phenyl and naphthyl azobenzene ( PnP and NpnNp ) as well as segmented copolyesters based on them. The twin series had the structure azobenzene–oligooxyethylene–azobenzene, where the ethyleneoxy length was varied from 2 to 6 units. The LC properties of the twin series depended on the chemical structure of the azochromophore and also the length of the central oligooxyethylene segment. The PnP series exhibited smectic LC properties for n > three oligooxyethylene units. Conversely, NpnNp series exhibited spherulitic phases only for the shortest member – Np2Np . One non‐LC short spacer twin ( P2P ) and one LC long spacer twin ( P6P ) were incorporated as part of a main chain polyester composed of fully aliphatic segments of sebacate and di or tetraethylene glycol (DEG/TEG) units by melt polycondensation. Non‐LC P2P formed LC polymers even at low (5 mol %) incorporation in DEG‐based copolymers, whereas the LC‐ P6P could do so only at 30 mol % incorporation. The LC properties of the twin molecules as well as copolymers were studied using differential scanning calorimetry, polarized light microscopy (PLM) along with variable temperature wide angle X‐ray diffraction. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012     

Interlayer shear strength of single crystalline graphite

Reported values(0.2 MPa-7.0 GPa) of the interlayer shear strength(ISS) of graphite are very dispersed.The main challenge to obtain a reliable value of the ISS using conventional measuring methods was the unavailability of sufficiently large single crystalline graphite.Here we present a novel experimental method to measure the ISS,and obtain the value as ～0.14 GPa.Our result can serve as an important basis for understanding mechanical behavior of graphite or graphene-based materials.     

饲料中补充晶体蛋氨酸和羟基蛋氨酸钙对罗氏沼虾幼虾生长性能的影响

饲料中添加30%鱼粉为对照组饲料和6组试验饲料(分别替代对照组中16.67%、33.33%和50.00%的鱼粉,同一鱼粉替代水平的2组分别添加晶体蛋氨酸和羟基蛋氨酸钙,使其蛋氨酸含量与对照组一致)喂养罗氏沼虾(初始体重为(0.29±0.04) g )10周,研究不同鱼粉替代水平下,分别添加晶体蛋氨酸和羟基蛋氨酸钙对罗氏沼虾幼虾生长性能和血清生化指标的影响.结果表明：复合蛋白源替代对照组16.67%鱼粉并补充羟基蛋氨酸钙组的增重率、特定生长率、蛋白质效率和饲料系数同对照组无显著差异(P>0.05);同一鱼粉替代水平下,羟基蛋氨酸钙组的增重率、特定生长率和蛋白质效率均显著高于晶体蛋氨酸组(P<0.05).血清生化组成的分析结果表明：血清总蛋白含量各处理组之间差异显著(P<0.05),对照组血清谷草转氨酶和谷丙转氨酶活力显著低于其他各组(P<0.05),其中同一替代水平下,饲料中添加羟基蛋氨酸钙组谷草转氨酶和谷丙转氨酶活力低于添加晶体蛋氨酸组.由此可见,与晶体蛋氨酸相比,羟基蛋氨酸钙能更有效提高罗氏沼虾生长性能和饲料利用效率.     

分布式系统调试器IVD的系统实现

介绍了一个自主式智能车辆AIV系统的分布式系统测试床IVD系统.首先讨论了IVD系统的设计目标,然后在介绍AIV结构的基础上,详细地分析了IVD系统,按实时在线调试和离线重放两种情况进行一一讨论.该系统已在智能车辆AIV系统开发及调试实验中得到应用,实验结果验证了该系统是进行在线实时观察,离线分析问题的强有力的工具.