Low temperature crystallographic data on Kevlar 49 fibres

Using X-ray diffraction data, the behaviour of Kevlar 49 fibres at low temperatures, up to –100°C, has been analysed. During cooling, the basal plane of the monoclinic unit cell shrinks whereas the c- (unique, chain axis) length is not significantly affected. In contrast, in the return heating cycle to ambient temperature, the basal plane expands and contraction occurs along the chain direction. The unit cell registers a reduction in volume in both the cooling and heating cycles. Conspicuously, after a cycle of cooling and heating, the unit cell does not return to its initial volume.     

钢筋砼压弯剪构件抗震性能试验研究

本文根据146根钢筋砼压弯剪构件的试验结果,分析了压弯剪构件在低周往复荷载作用下的破坏形态,并提出了相应于各种破坏形态的强度计算方法。建立了低周往复荷载作用下压弯剪构件的延性系数及极限转角的计算公式和防止粘结破坏的构造措施。     

X-ray studies on crystalline complexes involving amino acids and peptides XXXIV. Novel mode of aggregation, interaction patterns and chiral effects in the maleic acid complexes of DL- and L- arginine

Amino acid - carboxylic acid complexes provide useful information in relation to molecular interactions in present day biological systems and to prebiotic self-organisation. The crystal structures of the complexes of maleic acid with DL- arginine (orthorhombic; Pca2(1); a=15.9829, b=5.4127, c=16.1885; R=0.0522 for 956 reflections) and L- arginine (triclinic; P1; a=5.2641, b=8.0388, c=9.7860, alpha=106.197, beta=97.275, gamma=101.64; R=0.039 for 1749 reflections) have been determined. The complexes are made up of positively charged zwitterionic arginine molecules and negatively charged semi-maleate ions which contain an intramolecular symmetric O-H-O hydrogen bond. In both the structures, the amino acid molecules aggregate into layers. In each layer, S2 head-to-tail sequences are interconnected through specific intermolecular interactions between alpha-carboxylate and guanidyl groups, an arrangement observed for the first time in crystal structures involving arginine. The carboxylate-guanidyl interactions are of different types in the two complexes and consequently aggregation patterns in them exhibit substantial differences. Interactions between the amino acid layers involve the semi-maleate ions in both the complexes. In addition, water-bridges also exist in the L complex. The full potential of the guanidyl group for specific interactions is realized in both the structures. The L complex contains an array of water-mediated salt bridges. The structures demonstrate that the effect of chirality on molecular aggregation can span a wide range.     

Bulk and interfacial physical properties of aqueous solutions of sodium lauryl sulphate: Part IV: Dilute aqueous solution behavior by electron spin resonance studies and by pH and surface tension measurements

The electron spin resonance spectrum of the nitroxide label 2,2,6,6 – TetraMethyl – 4 – Piperidone – Oxide (TEMPO) has been investigated in aqueous solutions of a purified and commercially available impure samples of sodium lauryl sulphate (NaLS) for a wide range of concentrations. The spectra were recorded at 24°C as a function of surfactant concentration. The reorientational correlation times T_θ of the TEMPO label in aqueous solutions were calculated using the Kivelson's theory. Using the T_θ data qualitative analysis has been carried out in an attempt to understand the microscopic effects produced by the hydrophobic part of the surfactant on the water structure and the hydrophobic-hydrophobic interactions in water. Four major discontinuities in the τ_θ results have been identified with the purified NaLS system. They are found to occur at NaLS concentrations of 0.008 wt.%, 0.015 wt.%, 0.23 and 1.73 wt.%. The latter two concentrations represent the first and the second critical micelle concentration (CMC) of the surfactant while the first two concentrations reveal the existence of premicellar association and dissociation processes, respectively. These discontinuities have been also confirmed by the pH data and by surface tension results from the du Noüy ring method. The effect of addition of lauryl alcohol and sodium chloride on τ_θ values was also studied. The additive action has been found to produce an additional discontinuity, corresponding to the mixture CMC, in the τ_θ versus concentration plot. Analysis of other effects such as solution aging and hydrolysis of NaLS are also included. The applicability of the spin labelling technique for the study of aqueous solution behavior of NaLS is discussed by comparing data reported in the literature.     

Single- and few-layer graphene growth on stainless steel substrates by direct thermal chemical vapor deposition

Increasing interest in graphene research in basic sciences and applications emphasizes the need for an economical means of synthesizing it. We report a method for the synthesis of graphene on commercially available stainless steel foils using direct thermal chemical vapor deposition. Our method of synthesis and the use of relatively cheap precursors such as ethanol (CH(3)CH(2)OH) as a source of carbon and SS 304 as the substrate proved to be economically viable. The presence of single- and few-layer graphene was confirmed using confocal Raman microscopy/spectroscopy. X-ray photoelectron spectroscopic measurements were further used to establish the influence of various elemental species present in stainless steel on graphene growth. The role of cooling rate on surface migration of certain chemical species (oxides of Fe, Cr and Mn) that promote or hinder the growth of graphene is probed. Such analysis of the chemical species present on the surface can be promising for graphene based catalytic research.     

中国电影科研所赴美考察报告

中国电影科研所近期组团赴美进行了专题业务考察，此行主要目的是了解国际上在数字中间片技术、数字电影拍摄技术和数字影院技术方面的最新进展，就我所数字中间片实验室的建设和正在进行的相关研究项目与国外同行进行交流，顺便了解一些电影数字化修复工艺和技术的情况。     

新加坡电影业和数字影院技术的发展概况

近年来，在新加坡政府的支持及各项政策的推动下，新加坡数字技术应用和网络资讯科技的发展位于世界领先地位，特别是电影放映业取得较大发展，票房收入不断提高。为了解新加坡数字电影放映技术的最新发展情况及其市场运作模式，3月27日至4月1日，中国电影科研所电影技术考察组在新加坡进行了为期4天的专访和考察。考察期间我们与新加坡有关政府部门的代表、相关公司的主要负责人和技术专家进行了交流和座谈，现将考察情况综述如下。     

Single mode waveguide properties of m-NA doped Au/PVA nano-composites: Synthesis, characterization and studies

Meta-nitroaniline (m-NA) doped gold/polyvinyl alcohol (Au/PVA) nano-composites are prepared via in-situ reduction of gold salt by employing hydrazine hydrate (HH). Effect of the NLO (non-linear optical) active m-nitroaniline (m-NA) on the photo-physical properties of nano-particles of gold is studied in the colloidal as well as self-supported film form. The UV-Visible absorption bands between 530 and 555 nm due to surface plasmon resonance in Au nano-particles are observed. The absorption values show a shift in the position due to variation in m-NA with respect to the gold concentration. Additional absorption bands are observed after m-NA doping that influences the original position of gold absorption bands. The solutions and the films are further characterized by photoluminescence (PL), FTIR spectroscopy, XRD, TEM and thermal analysis. The particle size as shown by TEM is found to be less than 10 nm. Spin cast nano-composite films show single mode waveguide properties.     

欧洲电力需求侧管理对中国的启示(上)——来自中国赴欧洲电力需求侧管理的培训报告

学习借鉴欧洲国家开展电力需求侧管理的经验,对促进我国电力需求侧管理深入发展、建设资源节约型社会具有重要现实意义。全面介绍了欧盟成员国在开展需求侧管理、能效管理、能源服务等方面的行政法规、标准标识、财税政策以及市场激励、市场交易、市场竞争机制,在建筑节能和发展可再生能源方面形成的相关的制度体系。分析了我国电力需求侧管理工作的不足,并从出发点、政府作用、实施重点和实施手段上进行了国际比较,对进一步推动电力需求侧管理工作提出了加强法律法规建设、加快建立激励机制、加强标准和评估体系建设、大力开发应用新技术等政策性建议。深入挖掘电力需求侧管理资源,应成为我国建设节约型社会的重要战略举措。