高温使用性能获得改进的三元乙丙橡胶胶料

虽然三元乙丙橡胶(EPDM)属于耐热性弹性体,但其耐热性还可通过选用一种特殊的聚合物结构以及适当的添加剂,如:氯磺化聚乙烯和三氧化二锑获得进一步改进。适当的防老剂也能提高三元乙丙胶硫化胶的耐高溫性能。     

碳纤维与复合材料的回顾(第一部分)

在论文将分为两部分,目的是要回顾碳纤维及其原丝的生产技术、纤维结构及其主要性能(第一部分).并总结目前树脂基或水泥基碳纤维复合材料的现状(第二部分)。     

杀螟硫磷原药和制剂气相色谱测定法的协作研究

世界卫生组织(WHO)于1973年首次把杀螟硫磷(fenitrothion)编入农药规格手册。有效成份的分析采用滴定法,该法基于杀螟硫磷在酸性溶液中被锌还原,然后用亚硝酸钠滴定还原产物胺。方法包括原药及其可湿性粉剂的测定。这一方法并不是专一的而且费时。在WHO杀虫剂化学与规格专家委员会1977年会议上,J.W.Miles和D.L.Mount     

含有较多烯丙基氯的聚氯乙烯的降解与阳离子改性

通过控制脱氯化氢以制备出含有较高烯丙基氯的无色聚氯乙烯—PVC(A)。同原来的树脂相比,PVC(A)的热稳定性和光氧化稳定性有所下降。PVC(A)初始脱氯化氢速度与烯丙基氯含量成直线关系。用MezCpAl处理PVC(A)生成戊二烯化的聚氯乙烯(PVC—CP)而引起凝胶,并且用马来酸酐可破坏凝胶。PVC(A)/BCl_3/异丁基烯体系使异丁基烯充分接枝,产生带有叔基氯端基的聚异丁烯支链。后者经Me_2CpAl处理再次成二烯化,产生可被马来酸酐溶解的交联网。     

以赛车为名——2014泛珠三角超级赛车节春季赛报道

正这里,是中国场地赛车的发源地;这里,有着国内氛围最火爆的超级赛车节——泛珠三角超级赛车节;这里,是珠海。而今年,是泛珠三角超级赛车节诞生的第十个年头。这九年中,泛珠伴随着中国汽车文化、汽车运动的发展而成长,其商业价值与文化氛围在成长的过程中逐渐开始凸显,期间也获得了许多的荣誉。在刚刚结束的2014泛珠春季赛里,我们看到了泛珠改变的地方,也看到了泛珠的不变之处。     

Influence of maize kernel hardness on flour hydration and cooking properties

Knowledge of the association between cooking properties and endosperm hardness may help nutritionist and processors to select raw materials for preparing maize based food products, particularly those eaten as cooked dispersions. Seven commercial maize cultivars differing in hardness were selected to evaluate endosperm hardness on the kernels and some characteristics such as composition and hydration and cooking properties on the grits obtained from those maizes. Results show that the differences in endosperm hardness (directly related to grits protein content) can explain the differences in swelling and amylographic consistencies values. Cultivars with the hardest endosperm show the lowest values at high temperature. They also show the lowest amylographic consistencies. On the other hand softer endosperms present the highest swelling power and the highest amylographic consistencies. These differences are attributed to the restriction for starch swelling caused by the protein matrix. Endosperm hardness measurements and swelling power at 95 degrees C, can be useful to select cultivars that are going to be used to prepare maize based foods like atoles, polenta, etc.     

Assessment of response function in two PET scanners with and without interplane septa

The authors have assessed the response function both experimentally and theoretically for two commercial tomographs: CTI 931/08-12 and CTI 953B with and without interplane septa. Monte Carlo simulations were undertaken using the GEANT package from CERN. Spatial resolution (tomographic and axial) was calculated for line sources at various positions in the field of view. Sensitivity and scatter fraction (SF) were calculated for various source geometries as a function of energy discrimination. A very realistic response function in positron emission tomography (PET) is obtained by Monte Carlo methods, using global parameters to account for unsimulated phenomena such as scintillation light transport inside a detector block and its sharing among the various phototubes. Minor discrepancies remain for sensitivity and SF at high energy thresholds and may probably be explained by introducing the observed dispersion in the energy response for the various crystals within a detector block.     

爆炸粉末冶金 第一部分

爆炸粉末冶金作为一种难熔金属和超合金潜在的加工技术,本文作了介绍。这些材料的难加工性向加工工业提出了挑战。本文介绍了一种球形爆炸压制装置,以期概括地描述一下工业生产所需的参数,并得出与圆柱形爆炸压制方法的相互关系。     

设计电解槽阳极时应考虑的因素

序言铝工业趋向采用低电流密度的大型多爪头阳极,所以考虑对使用中阳极有影响的起作用的机械应力和热应力的设计因素变得更加重要。设计时应该使合成应力不超过碳块的机械强度极限,同时要使钢爪和碳块间的接触电压降为最小。     

国际镍公司 Acton 贵金属精炼厂的溶剂萃取

由于安大略省 Sudbury 地区的 Cu-Ni 硫化矿中含有微量贵金属,因而使得国际镍公司包括了贵金属的精炼。最初发现该矿,大约在一百年前,即1883年。六年后,在此矿床中发现了重要的铂族金属矿物—砷铂矿(PtAs_2)。通常供国际镍公司精炼厂用的矿石,其含量为1ppm 左右的铂族金属,还有引人注意的大量的 Au 和 Ag。