纳米二氧化钛对MQ硅树脂增强硅橡胶性能的影响

以MQ硅树脂增强加成型硅橡胶为基体,采用机械共混方式,加入少量纳米二氧化钛进行改性,制备了纳米二氧化钛改性硅橡胶。试验结果表明,MQ硅树脂增强的硅橡胶中,加入少量纳米二氧化钛改性后,能够改善硅橡胶的力学性能,其硬度和断裂伸长变化不大,而拉伸强度和抗撕强度提高,硅橡胶的耐热性也提高。溶胀实验表明,添加纳米粒子后,硅橡胶的溶胀比降低,凝胶质量分数和交联密度增加。     

模2n加整体逼近模2加产生的噪声函数的概率分布研究

该文证明了模2n加变换以6种不同的方式整体逼近模2加时产生的噪声函数取值概率的数值分布相同,给出了6种噪声函数的概率分布之间的相互转化关系,并给出了6种整体逼近所产生的噪声函数的取值概率的计算公式以及概率值平方和的计算公式,并修正了三元模2加整体逼近模2n加时所产生的噪声函数取值概率的平方和的计算公式。这些结论在区分攻击中有一定的应用价值。     

Dynamic Probabilistic Caching Algorithm with Content Priorities for Content‐Centric Networks

This paper presents a caching algorithm that offers better reconstructed data quality to the requesters than a probabilistic caching scheme while maintaining comparable network performance. It decides whether an incoming data packet must be cached based on the dynamic caching probability, which is adjusted according to the priorities of content carried by the data packet, the uncertainty of content popularities, and the records of cache events in the router. The adaptation of caching probability depends on the priorities of content, the multiplication factor adaptation, and the addition factor adaptation. The multiplication factor adaptation is computed from an instantaneous cache‐hit ratio, whereas the addition factor adaptation relies on a multiplication factor, popularities of requested contents, a cache‐hit ratio, and a cache‐miss ratio. We evaluate the performance of the caching algorithm by comparing it with previous caching schemes in network simulation. The simulation results indicate that our proposed caching algorithm surpasses previous schemes in terms of data quality and is comparable in terms of network performance.     

Addition of tetrachloromethane to alkenes catalyzed by cobalt(II)-amine complex

The cobalt(II)-2-methylpropylamine complex is an efficient catalyst for addition of tetrachloromethane to alkenes under mild reaction conditions (80 °C) providing 1 1 adducts up to 99.5% yield. Reactions with vinyl monomers provided low yield of 1 1 addition products (5–48%) presumably due to radical chain processes favoring telomerization and polymerization.     

Hydrogen-storage properties of a Mg-based mixture prepared by reactive mechanical grinding with ultrafine Fe2O3 particles and Ni

The sample Mg-10 wt.% (Fe₂O₃, Ni) was prepared by grinding Mg mechanically under H₂ (reactive mechanical grinding) with ultrafine Fe₂O₃ particles and Ni particles. The sample Mg-10 wt.% (Fe₂O₃, Ni) as milled absorbed 4.24 wt.% hydrogen at 593 K under 12 bar H₂ for 60 min. Its activation was accomplished only by one hydriding–dehydriding cycle. The activated sample absorbed 4.05 wt.% hydrogen at 593K, 12 bar H₂ for 60 min and desorbed 3.05 wt.% hydrogen at 593 K, 1.0 bar H₂ for 60 min. After hydriding–dehydriding cycling, Fe₂O₃ was reduced, Mg₂Ni was formed by the reaction of Mg with Ni, and a small fraction of Mg was oxidized.     

Urethanic compounds with Schiff base structure

Our study dealt with the synthesis and characterization of new azomethine-urethane compounds, starting from 2,2′-[ethylenebis(nitrilomethyli-dyne)]diphenol, 2,2′- [propylenebis(nitrilomethylidyne)]diphenol, 2,2′-[butylene bis(nitrilomethylidyne)]diphenol, 2,2′-[pentylenebis(nitrilo- methylidyne)]diphe-nol, 2,2′-[hexamethylenebis(nitrilome-thylidyne)]diphenol and phenyl isocyanate for the model compounds and tolylene-2,4-diisocyanate for the polymers. The products were characterized by IR and ¹H-NMR spectroscopy, thermogravimetry, DSC. Through heating, these compounds suffer chemical modification, both addition and condensation reactions being possible. Received: 18 September 2000 / Reviewed and accepted: 20 September 2000     

环己基甲基二甲氧基硅烷的合成工艺探讨

介绍环己基甲基二甲氧基硅烷的几种合成方法，并对其工艺方法的优劣作了述评。     

Effect of Re and Mo addition upon liquid phase methanol reforming with water over SiO2, ZrO2 and TiO2 supported Ir catalysts

Two different enhancement manners of Re and Mo additives have been studied in liquid phase methanol reforming with water over SiO₂, ZrO₂ and TiO₂ supported Ir catalysts. In the cases of Ir–Re/SiO₂ and Ir–Re/ZrO₂, hydrogen formation rate was accelerated remarkably by the formation of some nanocomposites between Ir and Re. On the other hand, in the case of Ir–Mo/TiO₂, the formation of thin monolayer-like structure of MoO₂ on TiO₂ surface was important for the acceleration of hydration process of partially dehydrogenated methanol with adsorbed water which was activated over thin MoO₂ overlayer.     

Accelerated startup of biological hydrogen production process by addition of Ethanoligenens harbinense B49 in a biofilm-based column reactor

Two biofilm-based column reactors with walnut shell (WS) as carrier media were applied for fermentative hydrogen production using glucose as substrate by mixed microbial cultures at the temperature of 35 °C. Pure hydrogen producing bacteria Ethanoligenens harbinense B49 was supplemented into the reacting system periodically or continuously to enhance hydrogen production ability at the startup period. The results showed that the bioreactors supplemented with E. harbinense B49 performed better than the reactor without bacteria addition. Continuous addition mode was recommended, since the hydrogen production performance was better and the operation was easily to be accomplished. The optimal addition amount of pure bacteria was also investigated. The optimal bacterial addition amount was found to be 2.5% which led a better hydrogen production rate. In addition, the bioreactor supplemented with pure bacteria continuously presented a high hydrogen production ability as the specific hydrogen production rate (SHPR) maximized at 1.36 L/g-VSS·d; whereas, the bioreactor without bacteria addition obtained a maximum specific hydrogen production rate of 1.10 L/g-VSS·d. The addition of E. harbinense B49 favored the transformation to ethanol type fermentation in the bioreactor. Thereby, the startup period had been accelerated remarkably.     

2005-2008年全国减肥类保健食品违法添加药物状况调查及分析

目的:调查中国减肥类保健食品中违法添加药物的情况及其变化趋势.方法:通过健康相关产品国家卫生监督抽检,在严格的质量控制下,本研究采用UPLC-MS/MS确证方法连续4年对减肥类保健食品中15种化学药物进行监测.结果:377件样品中违禁药物的检出率呈逐年降低的趋势.胶囊类样品检出率57.8%(118/204)明显高于其他剂型.西布曲明的检出率呈逐年降低的趋势,而酚酞的检出率呈逐年升高的趋势.2008年联合用药的样品占全部阳性样品的比例高达41.7%.结论:减肥类保健食品中违法添加药物的情况仍然十分严重,尤其是联合用药应引起监管部门关注.