Nanoscale artifacts in RuO4-stained poly(styrene)

This research studies the effects of RuO₄ exposure on various samples of poly(styrene) (PS). Transmission electron energy-loss spectroscopy (EELS) shows a decrease in the 7 eV π-π∗ transition characteristic of aromatic rings in PS indicating that RuO₄ covalently alters aromatic character. Imaging and selected-area electron diffraction show that a layer of RuO₂ solid forms on the surface of bulk PS specimens exposed to RuO₄. High-resolution TEM imaging (HREM) shows that RuO₂ nanocrystals consistently condense on specimen surfaces, independent of the chemical nature of the specimen below. These nanocrystals modulate contrast at length scales on the order of 2-5 nm in TEM images and limit resolution at nanometer length scales.     

Partial or total silylation of dextran with hexamethyldisilazane

The silylation reaction of dextran with 1,1,1,3,3,3-hexamethyldisilazane (HMDS) in DMSO was studied as the first step of the synthesis of new amphiphilic polyester-grafted dextrans. According to the experimental conditions, i.e. dextran molar weight, medium temperature and reaction time, HMDS/OH ratio, addition of a catalyst and co-solvent, partially or totally silylated dextrans were recovered. The highest silylation yields were obtained with the lowest molecular weight dextrans. The increase in temperature medium and/or reaction time, the presence of catalyst or co-solvent favored the protection yield. Whatever the dextran used, complete silylation of the polysaccharide chain could be achieved by adequate selection of the experimental conditions. The thermal properties of resulting silylated polysaccharides were investigated by temperature modulated DSC. It was observed that T_g values of partially silylated dextran were maintained between 120 and 140 °C, independently of the dextran molecular weight. Interestingly, DMSO proved to behave as an efficient plasticizer of (partially) silylated dextrans. The partially silylated dextrans were efficiently used as multifunctional macroinitiators for the controlled ring-opening polymerization (ROP) of lactone. The ROP was then promoted from the remaining hydroxyl groups in the presence of tin or aluminium activator. After polymerization and ultimate deprotection of the silylated dextran backbone, amphiphilic polyester-grafted dextrans were readily recovered.     

MB-86型丙烯腈催化剂的工业应用

MB-86丙烯腈催化剂通过大庆石化总厂化纤厂7000吨/年丙烯腈装置工业应用,丙烯腈单程收率80％以上,丙烯单耗为1.05—1.08吨/吨丙烯腈。工业运转结果表明,MB-86催化剂稳定性及耐磨性良好,反应产物分布合理。可用于原使用C_(41)、C_(49)及类似系列催化剂的万吨级丙烯腈工厂,反应器不必进行改造。     

PVC／NBR／HDPE共混体系相容性研究（Ⅰ）增容剂对力学性能的影响

采用丁腈橡胶（ＮＢＲ）及其氢化还原后产物（ＨＮＢＲ）为ＰＶＣ／ＨＤＰＥ共混体系的增容剂，研究了增容剂结构、用量及丙烯腈含量对共混体系相容性的影响。发现丁腈橡胶（ＮＢＲ２９及ＨＮＢＲ２９）对ＰＶＣ／ＨＤＰＥ体系有较好的增容作用，而ＮＢＲ４０及ＨＮＢＲ４０较差。当增容剂用量为２％，ＰＥ含量为８％～１２％时，共混物具有较好的相容性，力学性能得到改善。     

The peeling of flexible probabilistic fasteners

Probabilistic fasteners are attachment devices consisting of two elements each of which is covered by an array of outgrowths or protuberances which interact or interlock with those on the opposing surface to form a bond which can be made and detached many times. A number of peel tests are described in which the behaviour of such bonds, specifically those formed by Velcro® hooks and loops and Dual Lock®, has been explored. The value of the specific energy of detachment of such mechanically latched systems can be related to the geometry and material properties of the individual fixing elements. Similar arguments can be applied, both qualitatively and quantitatively, to some natural systems such as the spines on some cacti.     

有机纤维材料用软膜乳液阻燃剂的制备

采用甲醛、尿素、三聚氰胺、脒基脲磷酸盐为原料,以硼砂、硼酸、氨水为pH调节剂合成了保护胶;在保护胶存在下,以预乳化的丙烯酸酯混合单体于82-88℃共聚合成乳液,将其涂布于有机纤维材料,干燥后得软膜透明阻燃涂层。用其处理的涤棉布阻燃性能为:损毁长度68mm、续燃时间1s、阴燃时间3s、氧指数62、吸附干量287g/kg,处理的纸板的阻燃性能为:平均炭化长度77mm、平均续焰时间2s、平均续灼燃时间32s、吸附干量283g/kg。     

ε－拟可微规划的Fritz John型条件和Knhn－Tucker型条件

讨论了不等式约束下的ε－拟可微规划的局部最优解问题，给出了这一问题的ＦｒｉｔｚＪｏｈｎ型条件和Ｋｕｈｎ－Ｔｕｃｋｅｒ型条件，本文也是对Ｇｏｒｏｋｈｏｖｉｋ结果的推广     

α－Al_2O_3衬底上生长的GaN膜的光学性质

采用金属有机化学气相淀积（ＭＯＣＶＤ）方法生长了α－Ａｌ２Ｏ３衬底上外延的高质量的单晶ＧａＮ薄膜。Ｘ射线衍射光谱与喇曼散射光谱表征了ＧａＮ外延薄膜的单晶结构和单晶质量。透射光谱和光调制反射光谱定出了六角单晶ＧａＮ薄膜的直接带隙宽度和光学参数。     

水利工程排涝减灾效益分析与计算

在分析涝灾成因特点基础上对涝灾进行了重新定义，在研究涝灾损失及 排涝效益时引入了临界降雨量的概念，从而奠定了水利工程排涝减灾效益分析与计算的理论基础，并给了效益计算的一般计算模型。     

动态力学及介电法研究蓖麻油丙烯酸酯共聚网络悬挂链的弛豫运动

用动态力学（内耗）和介电方法研究了由蓖麻油（ｃａｓｔｏｒｏｉｌ）、甲苯二异氰酸酯（ＴＤＩ）、丙烯酸羟乙酯（ＨＥＭＡ）组成的网络（Ａｉ）和由正己醇取代Ａ网络中部分ＨＥＭＡ组成的网络Ｂｉ（ｉ＝０，１，２，３）两种网络的内耗及介电损耗，内耗峰强度随悬挂链数目增加而升高，证实了网络破坏后形成的悬挂链的运动对内耗及介电损耗峰高有明显的贡献。