The multi-structure of oxidized-reduced tungsten carbide surface(s)

The XPS of bulk tungsten carbide, partially oxidized WC surfaces at 373 and 573 K as well as tungsten trioxide have been reported. Bulk WC has been prepared from WO₃ as a starting material in a mixture of CH₄ (20%) and H₂ (80%) at 1150 K for 4 h, while partially oxidized WC surfaces were prepared by oxygen chemisorption on a clean WC surface at 200 K, then the temperatures were raised to 373 and 573 K respectively. The XPS of a freshly prepared WC reveals the presence of a small amount of WO₃ on the surface and a slightly higher concentration in the bulk. The oxygen-exposed fresh WC surfaces and surfaces treated at temperatures higher than 373 K show the presence of WO₃ in a considerable quantity depending on the length and the treatment temperature. Ar⁺ bombardment of this partially oxidized surface reduces WO₃ to WO₂ and W(0), while WC is partially reduced to W(0). Isomerization reactions of alkanes on oxygen-exposed WC surface occurs in reality on a composite surface structure containing WC, WO₃, WO₂ and elemental W(0).     

贵定露天石灰石矿不稳定边坡的治理

着重讨论了贵定石灰石矿边坡１２２０～１１８０ｍ水平在Ｉ号剖面左右深层不稳定地段的边坡治理方案。推荐方案强调多台阶同时回采，以推迟靠帮，进而推迟可能的表层滑坡治理。还讨论了护坡矿壁回收及该矿其他不稳定地段边坡治理等问题。     

APPLICATION OF A COMMERCIAL ENZYME PREPARATION IN THE BARLEY MALTING PROCESS

This paper presents data on barley micromalting with addition of the CELLUCLAST enzyme complex. This is a commercial, multicarbohydrase with distinct β-glucanase and proteinase activities. The enzyme was added to steeping and germination phases, in different quantities (0.05%; 0.75% and 0.1% of initial barley). The enzyme was added to different malting phases: to the 2nd and 3rd steep water, at the beginning of germination on the 1st day by spraying, on the 2nd day of germination and in combination of addition to 3rd steeping water and in germination start (50% of total quantity of each). CELLUCLAST enzyme had a significant effect on reduction of wort viscosity, extract difference, wort filterability and protein breakdown, depending on the quantity of added enzyme and the malting phase to which it was added. There was no negative effect on other malt quality parameters. The best values of cytolytic breakdown parameters (viscosity, extract difference, filtration rate) were obtained with addition of 0.075% of CELLUCLAST, on the first day of germination.     

基于SolidWorks的螺杆压缩机机体三维建模设计

应用SolidWorks软件,建立了螺杆压缩机机体三维实体模型.对螺杆压缩机机体的内、外螺旋面的建模进行了分析和研究,提出了建立分段螺旋面模型的基本思路和方法.     

超细分子筛材料的合成与应用研究进展

综述了近几年超细分子筛的合成与应用方面的研究进展,重点介绍了几种常用且研究较多的分子筛,主要包括Y,ZSM-5,β,Silicalite-1,ZSM-35,MCM-22等分子筛。对超细分子筛的合成方法及其在石化、环保和生物等领域的应用进行了介绍,并对分子筛复合材料的研究及应用的最新动态进行了评述,说明超细分子筛材料的应用领域仍在不断拓宽,超细分子筛复合材料的研究将会成为分子筛材料领域未来的重要发展方向。     

多层住宅砖混房屋设计中两点问题的探讨

浅议多层住宅砖混房屋中构造柱的作用及设置方法；探讨了砖混结构墙下条形基础底面积重复利用问题及其解决方法。     

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.     

催化重整装置的几点设计改进

以一套500kt/a规模的催化重整装置的设计为例进行分析和讨论，提出对今后催化重整装置设计的几点改进建议，包括原料的加氢预处理流程，提纯重整产氢，优化预分馏塔及稳定塔的塔盘层数，选择合适的预加氢进料换热器及甲苯塔、二甲苯塔的加压操作等。     

如何提高干式喷射彩色混凝土的观感质量

从彩色混凝土喷射施工的特点出发，结合工程实例，分析了影响喷射彩色混凝土观感质量的原因和解决方法。指出彩色混凝土喷射工艺可以有效地解决大面积混凝土边坡与周围环境的协调性问题。