Equivalent Strains in Severe Plastic Deformation

The concept of equivalent plastic strain is discussed. Definitions may be based on kinematic arguments (like change of geometry) or on equivalence of plastic work. Complications arise when strain is accumulated in increments with variable strain path.     

在（311）面上所生长的Al_xGa_（1－x）As／GaAs单量子阱特性

文章报道了用分子束外延（ＭＢＥ）法在６００℃和６５０℃下，在Ｓｉ掺杂的ＧａＡｓ衬底的（３１１）Ａ和（３１１）Ｂ面上成功地生长了高质量的ＡｌｘＧａ１－Ａｓ／ＧａＡｓ单量子阱材料。计算了光荧光（ＰＬ）峰值能量，并与实验作了比较。讨论了（３１１）Ａ和（３１１）Ｂ面上的不同生长特性。     

Study on high-strength composite portland cement with a larger amount of industrial wastes

It is one of important measures for the sustainable development of cement industry to utilize industrial wastes. High-strength composite portland cement with a large amount of granulated blast furnace slag (GBFS), fly ash and limestone was prepared by separate grinding method, optimizing gypsum and using activators. The total amounts of blending materials are between 45% and 65% and the strength grades of cements reach 525 or even 625 according to Chinese national standard for composite portland cement. Besides setting time and strength, the hydration heat, drying shrinkage and sulfate resistance were also determined.     

钙钛矿型钛酸锶的制备、结构与性能

钛酸锶是一种具有重要电性质的陶瓷材料 ,因而在工业上得到了广泛的应用。本文介绍了钛酸锶的几种常见的合成方法 ,并简要的介绍了钛酸锶的结构与性能     

填充料细度对水工沥青混凝土性能的影响

近年来沥青混凝土作为防渗材料，在我国水工建筑中得到了广泛应用。与道路工程的沥青混凝土不同的是，水工沥青混凝土具有良好的粘弹性及抗渗性。目前，国家规范对填充料的细度尚无明确规定，通过调整沥青混凝土的填充料细工，对沥青混凝土的各项性能进行了系统的试验和分析，研究表明：适宜的填充料细度及掺量，能有效地改善沥青混凝土性能，提高其抗渗性。     

Thermophysical properties data: Government-university-industry cooperation in multidisciplinary research

Historical developments regarding the realization of the importance of reliable thermophysical properties data in engineering applications are presented. The events leading to the establishment of the Symposium on Thermophysical Properties in 1959 and the accomplishments of the symposia series since then are discussed. Contributions of the National Bureau of Standards to the thermophysical properties field are described.Welcoming address presented at the Ninth Symposium on Thermophysical Properties, June 24–27, 1985, Boulder, Colorado, U.S.A.     

High performance LDPE/thermoplastic starch blends: a sustainable alternative to pure polyethylene

Thermoplastic starch (TPS), as opposed to dry starch, is capable of flow and hence when mixed with other synthetic polymers can behave in a manner similar to conventional polymer-polymer blends. This paper presents an approach to preparing polyethylene/thermoplastic starch blends with unique properties. A one-step combined twin-screw/single screw extrusion setup is used to carry out the melt-melt mixing of the components. Glycerol is used as the starch plasticizer and its content in the TPS is varied from 29 to 40%.Under the particular one-step processing conditions used it is possible to develop continuous TPS (highly interconnected) and co-continuous polymer/TPS blend extruded ribbon which possess a high elongation at break, modulus and strength in the machine direction. The PE/TPS (55:45) blend prepared with TPS containing 36% glycerol maintains 94% of the elongation at break and 76% of the modulus of polyethylene. At a composition level of 71:29 PE/TPS for the same glycerol content, the blend retains 96% of the elongation at break and 100% of the modulus of polyethylene. These excellent properties are achieved in the absence of any interfacial modifier and despite the high levels of immiscibility in the polar-nonpolar TPS-PE system. The 55:45 blend possesses a 100% continuous or fully interconnected TPS morphology, as measured by hydrolytic extraction. This highly continuous TPS configuration within the blend should enhance its potential for environmental biodegradation. The elongation at break in the cross direction of these materials, although lower than the machine direction properties, also demonstrates ductility at high TPS concentrations. At a glycerol content of 36% in the TPS, the blends demonstrate only very low levels of sensitivity to moisture. A high degree of transparency is maintained over the entire concentration range due to the similar refractive indices of PE and TPS and the virtual absence of interfacial microvoiding.Effective control of the glycerol content, TPS concentration and processing conditions can result in a wide variety of morphological structures including spherical, fiber-like, highly continuous and co-continuous morphologies. These various blend morphologies are shown to be the determining parameters with respect to the observed mechanical properties.This material has the added benefit of containing large quantities of a renewable resource and hence represents a more sustainable alternative to pure synthetic polymers.     

(Nb,Ti)C的制备方法对(Nb,Ti)C-35Ni金属陶瓷的微观结构及性能的影响

用自蔓燃高温合成（SHS）技术及电弧熔融法制备的（Nb，Ti）C固溶体作基体，制备（Nb，Ti）C－35Ni金属陶瓷。结果表明用电弧熔融法制备的（Nb，Ti）C为基的试样具较优的室温力学性能（σ＝1630MPa，KIC＝18．0MPa），其陶瓷颗粒均匀分行粘结相之中并是包裹结构；而用SHS法制备的（Nb，Ti）C为基的试样其力学性能相对较差，其陶瓷颗粒无包裹结构．     

Studies of substrate specificities of lipases from different sources

Although lipases are widely applied in a wide variety of reactions, available information on the factors that are responsible for the substrate specificities of lipases from different sources is scarce. In this paper, nine lipase‐producing microorganism strains were isolated from oil‐containing samples. The properties of these enzymes, including pH optima, temperature optima, thermal stability, and pH stability, vary significantly with the different sources from which these lipases were isolated. The substrate specificities of the nine lipases, including fatty acid and positional specificities, were also studied. The fatty acid specificities of the nine lipases were observably different toward 15 substrates with different carbon chain lengths, different saturation degrees and different side chains. The lipases from S₃ Penicillium citrinum (PCL), MJ₁ Aspergillus niger (ANL), MJ₂ Aspergillus oryzae (AOL), YM Bacillus coughing (BCL), S₉ Geotrichum candidum (GCL), and S₁₁ Candida lypolytica (CLL) showed the strongest specificities to short‐chain esters, and the other lipases showed strong selectivity for medium‐ or long‐chain and branched esters. The positional specificities were examined by analyzing the hydrolytic products of triolein catalyzed by the nine lipases, using TLC. The lipases can be mainly classified into two groups by their specificities for the ester bond at position 2 of triglycerides; one group can selectively hydrolyze the ester bond at position 2 of the triglycerides, the other group cannot. All these nine lipases were divided into four groups by hierarchical clustering analysis on the basis of the results of fatty acid and positional specificities.