Composite Silica Particles Using a Mixture of Organosilane Monomers

Composite silica particles were synthesized by a two-step (acid-base) process in an aqueous solution with a mixture of organoalkoxysilane monomers. The two-step process separates the hydrolysis and condensation procedures to easily control condensation rate. In this study, the silane monomers used were phenyltrimethoxysilane (PTMS), vinyltrimethoxysilane (VTMS), methyltrimethoxysilane (MTMS), and tetraethyl-orthosilicate (TEOS). The physical properties of the resultant composite particles were investigated with the change in the molar ratio of monomers. The size of the particles increased with increasing the molar ratio of R_aSi(OR)₃/R_bSi(OR)₃ or R_aSi(OR)₃/TEOS (R_a: phenyl; R_b: vinyl, methyl).     

求解通信网节点间全部路由的逻辑代数化算法

经典的D IJKSTRA和BELLM AN-F LOYD通信网络路由算法,只能根据特定网络参数得到最佳路由,却无法获得网络存在的全部可用路由,而通信网理论研究及网络管理等方面,往往需要获得节点之间的全部可用路由.研究出一种路由新算法,遵循逻辑代数运算规则、采用关联矩阵中行与行之间整合与删除方式计算,N个节点的网络只需N-1次整合及删除运算,就能得到源节点到任意节点两点之间全部路由结果.详细论证了算法的正确性与合理性,简介了算法的并行运算可行性及与经典路由算法的兼容性等问题.通过算例详细说明算法的计算过程,并验证其正确性.     

Study on deactivation and regeneration of Pd/Al2O3 catalyst in hydrogen peroxide production by the anthraquinone process

Deactivated palladium catalysts in the hydrogenation of anthraquinione were regenerated with ethanol, nitric acid, hydrogen peroxide, boiling water and steam, respectively. The deactivated and regenerated catalysts were characterized by XPS, ICP, TG, FTIR, TPD, XRD, etc., and studied in the hydrogenation of anthraquinone. The results showed that the main cause of catalyst deactivation is the coverage of the active component by deposits. The treatments by hydrogen peroxide and boiling water can effectively regenerate the deactivated catalysts. This revised version was published online in August 2006 with corrections to the Cover Date.     

求解非线性规划问题的光滑路径跟踪方法

通过对非线性规划问题的K-T点的光滑路径跟踪方法研究，得出一种针对于既有不等式约束条件又有等式约束条件的优化问题光滑路径跟踪方法，证明了光滑跟踪路径的存在性。     

衡量网络可靠性的新模型

本文分析了传统的网络可靠性优化设计方法所存在的问题 ,给出了网络的通信通路数的定义 ,并基于网络的通信通路数给出了更能反映网络运行的实际情况的网络可靠性的定量模型 ,从而解决了传统网络可靠性优化设计方法所存在的问题 .     

基于三维矩阵重构争论有向图的域间路由振荡检测算法

边界网关协议(Border G atew ay P rotoco l,BGP)是当前In ternet域间路由协议的事实标准,基于策略的路由选择过程使它不再是严格意义上的距离矢量协议,也不再具有距离矢量协议的收敛性.V aradhan指出,自治系统各自为政的策略配置方式会导致全局策略冲突,引起永久性的路由振荡.针对该问题,G riffin利用稳定路径问题(S tab le Path P rob lem,SPP)模型形式化的抽象出BGP协议行为,并以此为基础提出了一种分布式的策略冲突检测算法,尽管该算法完全避免了传统方法的缺陷,但仍然存在泄漏策略信息和对BGP协议改动太大以及浪费网络资源的问题.本文提出了一种基于安全多方计算的检测路由策略冲突的方法,用于在怀疑BGP路由发生振荡时,动态的检测系统中是否存在策略冲突.该方法采纳了G riffin的理论基础,同时由于巧妙的运用了安全多方计算协议,可以完全解决G riffin算法的问题,具有很好的实用性.     

一类求解奇异延迟微分方程的两步连续Runge-Kutta方法的收敛性

本文给出了一类求解延迟落在当前积分步内延迟微分方程的两步连续Runge-Kutta方法。在一定条件下我们证明了方法收敛性,数值试验表明方法是有效的。     

水相湿法改性纳米碳酸钙表面性质的研究

用特定的表面改性剂在水相中对纳米碳酸钙的悬浮液进行了湿法改性。红外光谱和热失重分析证明,改性剂与碳酸钙之间以化学键结合;沉降体积和接触角的测定结果说明改性粒子在液体石蜡中的润湿性和疏水性得到了提高;透射电子显微镜照片显示改性粒子在液体石蜡中有更好的分散性;体系粘度实验表明改性粒子与液体石蜡之间有较好的相容性。     

Kinetics and mechanism of reaction of cis-α,β-dinitrostilbene with morpholine

Reaction of cis-,-dinitrostilbene (substrate) with morpholine (reagent) in n-hexane leads to cis--nitro--morpholinostilbene (end product). The process is of first order with respect to the substrate and second order with respect to the reagent. Possible reaction mechanisms are analyzed, and it is established that the following are most probable on the basis of kinetic patterns and stereochemistry: development of a charge transfer complex having a hydrogen bond between the substrate nitro group and reagent amino group; reaction of the complex with a second reagent molecule and formation of a carbanion (this stage determines the overall reaction rate); and detachment of a nitrite ion from the nitrocarbanion and its protonation to form the end product.N. N. Semenov Institute of Chemical Physics, Russian Academy of Sciences, 117977 Moscow. A. N. Nesmeyanov Institute of Heteroorganic Compound, Russian Academy of Sciences, 117813 Moscow. Translated from Izvestiya Akademii Nauk, Seriya Khimicheskaya, No. 1, pp. 78–83, January, 1992.     

Preparation and lithium doping of gallium oxynitride by ammonia nitridation via a citrate precursor route

Gallium oxynitride, isostructural to hexagonal gallium nitride (h-GaN), was obtained by ammonia nitridation of a precursor prepared from the addition of citric acid to an aqueous solution of gallium nitrate. Gallium oxynitride produced at 750 °C had a small amount of gallium vacancies, and was formulated as (Ga_0.89□_0.11) (N_0.66O_0.34) where the symbol □ stands for gallium vacancy. Both the gallium vacancies and oxygen substituted for nitrogen were randomly distributed within the structure. The amount of vacancies decreased with nitridation temperatures in the range of 750-850 °C. Approximately, 10 at% Li⁺ was doped into the gallium oxynitride, using a similar preparation with the additional presence of lithium nitrate, resulted in the random substitution of Ga³⁺ in an atomic ratio of Li/Ga<1 at 750 °C. Oxygen was codoped with lithium and substituted nitrogen in the wurtzite-type crystal lattice. These substitutions reduced the electrical conductivity in the gallium oxynitride semiconductor. A new oxynitride, Li₂Ga₃NO₄, was also obtained with Li₂CN₂ impurity using similar preparations from a mixture of Li/Ga?1. The crystal structure was isostructural with h-GaN, and was refined as P6₃mc with a=0.31674(1) nm, and c=0.50854(2) nm. The Ga and Li occupancies at the 2b site were refined to be 0.6085 and 0.3915, respectively, assuming that the other 2b site was randomly occupied with 1/5O and 4/5N. When the new compound was washed for over 1 min for the removal of Li₂CN₂ impurities, it was decomposed to a mixture of α-GaOOH and α-LiGaO₂. The as-prepared product with Li/Ga=1 showed the highest intensity in yellow luminescence among the products under excitation at 254 nm.