Shear ductility and toughenability study of highly cross-linked epoxy/polyethersulphone

The objective of the present study was to determine whether the ductility and toughenability of a highly cross-linked epoxy resin, which has a high glass transition temperature, T _g, can be enhanced by the incorporation of a ductile thermoplastic resin. Diglycidyl ether of bisphenol-A (DGEBA) cured by diamino diphenyl sulphone (DDS) was used as the base resin. Polyethersulphone (PES) was used as the thermoplastic modifier. Fracture toughness and shear ductility tests were performed to characterize the materials. The fracture toughness of the DDS-cured epoxy was not enhanced by simply adding PES. However, in the presence of rubber particles as a third component, the toughness of the PES–rubber-modified epoxy was found to improve with increasing PES content. The toughening mechanisms were determined to be rubber cavitation, followed by plastic deformation of the matrix resin. It was also determined, through uniaxial compression tests, that the shear ductility of the DDS-cured epoxy was enhanced by the incorporation of PES. These results imply that the intrinsic ductility, which had been enhanced by the PES addition, was only activated under the stress state change due to the cavitation of the rubber particles. The availability of increasing matrix ductility seems to be responsible for the increase in toughness. This revised version was published online in November 2006 with corrections to the Cover Date.     

A PROCESS OF PREPARING REPLICAS FOR THE SUBSTITUTION OF METAL SPECIMENS IN METALLOGRAPHIC STUDY

本文讨论如何应用“滴液盖片法”制造胶质代替膜来代替不透明的金属样品使能直接利用生物显微镜观察金属内结构,同时亦可利用金相显微镜观察而得到同一结果。     

Point-in-Polygon Analysis Under Certainty and Uncertainty

The point-in-polygon query in geographical information systems under certainty and uncertainty is formally analyzed in this paper. It is argued that points and polygons can be precise, fuzzy (imprecise), and random (with error) with different schemes of representations. Under certainty, points and polygons can generally be represented by their characteristic functions. Under imprecision induced uncertainty, they can be represented by fuzzy sets characterized by membership functions. If uncertainty is induced by randomness, points and polygons can be described by locational error models in which probability arguments are employed. Points and polygons under certainty turn out to be a special case of that under imprecision and randomness induced uncertainty.Since points and polygons may be precisely, imprecisely or randomly captured or recognized within a spatial information system, the point-in-polygon query is then rather complicated, and its entertainment is not straight forward. In general, the point-in-polygon query can be entertained under nine basic situations. It consists of the queries of whether a precise or fuzzy or random point is in a precise or fuzzy or random polygon. As a consequence, the answer to the query may take on various forms with certain types of uncertainty arguments attached. It involves the integrative utilization of fuzzy set and probability theories to derive the results.The present analysis clarifies some unresolved issues of the point-in-polygon query and provides a generalization to its entertainment. Furthermore, it sheds light on the way certainty and uncertainty can be addressed and implemented in spatial information systems.     

Using Einzymatic Proteolysis to Reduce Copper-Protein Catalysis of Lipid Oxidation

Copper-catalyzed oxidation of methyl linoleate was studied in a model emulsion systsm containing either proteins or their hydroly-sates. Experiments were conducted with egg albumin, sodium caseinate, and soy proteins. Both the TEA test and diene conjugation measurements revealed that the prooxidant effects of proteins can be reduced by protoolysis. The evidence indicates that the prooxidant activity of complexes of copper and intact proteins is greater than that of copper and proteolytic products. This reduction of prooxidant activity is another example of how proteolysis can improve the functional properties of proteins.     

The Relation of Viscosity, Nuclei Formation, and Crystal Growth in Titania-Opacified Enamel

This investigation shows that there is a relationship between viscosity, number of nuclei, and crystal growth during the firing of titania-opacified enamels. This agrees with a similar relationship which Tammann found in his experiments with organic glasses. The history of the development of the size, shape, and relative number of particles per unit area of titanium dioxide crystals was traced from 650° to 1300°C. As the temperature increased from 700° to 1100°C., the color of the specimens viewed under reflected light changed from light blue to white and then to cream-white. The methods used in this investigation were the measurement of viscosity, X-ray analysis, differential thermal analysis, and the study by light microscopy and electron microscopy of very thin heat-treated films which had been produced by blowing bubbles from high-temperature melts.     

Structure and morphology of the in situ composites of a liquid crystalline polymer and polycarbonate

In situ composites were prepared via melt blending of a liquid crystalline polymer (LCP) and polycarbonate using a twin screw extruder. The structure and morphology of these composites were analysed using both transmission electron microscopy (TEM) and scanning electron microscopy. The LCP phases were able to orientate and form in situ submicrometre fibres during the extrusion and post-extrusion drawing. TEM images as well as selected-area diffraction patterns were obtained from the materials. The effects of both composition, i.e. LCP content, and post-extrusion draw-down ratio on the development of the in situ formed LCP fibres were studied in detail. A skin–core morphological differentiation is observed in these materials where well-defined LCP fibres of higher aspect ratios were formed in the skin region. However, a significant amount of unelongated LCP particles were found coexisting with the less well-defined fibres in the core region of the extrudates. This skin–core differentiation was found to be dependent on the composition and the processing conditions, e.g. draw ratio. In this instance, electron microscopy is proven to be a powerful technique not only for direct observation of the formation, dimensions and morphology of the in situ LCP fibres, but also for the qualitative and quantitative characterization of the molecular orientation and crystalline structures in these fibres using selected-area electron diffraction. It is observed that the skin–core differentiation becomes more distinct in the in situ composites containing a higher percentage of LCP but diminishes when the material is processed at higher post-extrusion draw ratio.     

A NEW ALGORITHM FOR ESTIMATING THE RISK OF NATURAL DISASTERS WITH INCOMPLETE DATA

In this paper, we propose a new algorithm for estimating the risk of natural disaster based on incomplete data. To guarantee reliability in theory, we prove in this paper that the estimator obtained by the algorithm is asymptotically unbiased and mean squared consistent. We also give two simulation experiments showing the advantage of the algorithm. To demonstrate its practicality, we further employ the new algorithm to estimate, with only 9 observations, the risk of flood, drought and wind in Changsha county of Hunan Province in China. All results show that the new algorithm, which can unravel fuzzy information in incomplete data, is better than the main existing methods for risk estimation of natural disaster with small samples.     

香氛有多少种性格

香水是有个性的气味。一瓶香水里包括的成分，可以有鸢尾，百合，茉莉，玫瑰．铃兰或者橡苔。当然还有更多的，例如佛手柑，风信子．月桂．含羞草，甚至琥珀。懂得享受香氛的人．整整一个季节都可以在那瓶有色或透明的液体里给灵魂带来安宁或激情。