Silica Nanoboxes as New Nano-structured Materials: Their Secondary Synthesis from Alumina-Rich Zeolites

Novel silica nanoboxes were prepared by controlled dealumination of Na-X and Ca-A type zeolites using ammonium hexafluorosilicate (AHFS). The silica-richer the parent zeolite, the smaller the average pore size produced and the narrower the pore size distribution obtained. This was due to the specific reactivity of the extracting agent with the zeolite framework aluminum atoms. High temperature calcination of the dealuminated X-zeolite (ammonium form) resulted in mesoporous materials exhibiting an ink-bottle shape, a quite high surface area (330 m²/g, no micropores), an average pore diameter of 4.5 nm with a quite narrow pore size distribution (± 1.0 nm) and finally, a pore opening diameter of 3.9 nm. The latter was determined by using the nitrogen sorption isotherms (BET technique) and related pore volume data. The sorption behavior also suggested the interconnecting character of the newly created nanoboxes. The periodicity of these nanoboxes throughout the mesoporous material was clearly shown by X-ray powder diffraction at very small angles. These materials, herein called monomodal nanoboxes because of the absence of micropores in the structure, were also thermally stable. Incorporation of orthosilicate into the obtained silica nanoboxes, in accordance with the recently developed technique for pore size engineering in zeolites, led to materials with smaller pore openings but having almost the same textural properties. Solid superacidic materials were prepared by incorporating a liquid superacid (triflic acid or trifluoromethanesulfonic acid) into the silica nanoboxes using the wet impregnation technique. The maximum triflic acid loading which did not significantly affect the mesoporous framework of the materials was 24 wt%. As a reference, the maximum loading of less acidic sulfuric acid was slightly lower. All this showed the high chemical stability of the silica nanoboxes for supporting very acidic species. Temperature-programmed desorption using a combined DTA/TGA system allowed the identification of the bound phases and some liquid phase of the loaded triflic acid.     

Development of high-performance liquid chromatography criteria for determination of grades of commercial olive oils. Part I. The normal ranges for the triacylglycerols

Criteria for authentic olive oils were developed from isocratic high-performance liquid chromatography analyses of 99 olive oils from the major Mediterranean producers in the 1983–1986 crop years. Authentic olive oils include extra virgin, virgin and pure or refined oils, but exclude all reesterified and adulterated oils. The extra virgin through pure grades will have a combined area for the LOO (C_18:2C_18:1C_18:1), LOP (C_18:2C_18:1C_16:0), OOO (C_18:1C_18:1C_18:1), POO (C_16:0C_18:1C_18:1), POP (C_16:0C_18:1C_18:1), and SOO (C_18:0C_18:1C_18:1) peaks between 82.0 and 92.6% of the total area (L, linoleic; O, oleic; P, palmitic; S, stearic). Authentic oils will have ratios of LOO/LOP and OOO/POO that coincide with a line defined by OOO/POO=0.7844(LOO/LOP)+0.0968; correlation coefficient is 0.885. Authentic oils will not have a trilinolein (LLL) peak over 0.5% in area. Neither triolein (OOO) nor any other single peak suffices to characterize an olive oil sample as one of the authentic grades.     

基于计算智能的电站锅炉燃烧优化控制

燃烧优化是提升电站锅炉效率降低污染物排放的有效途径;计算智能是目前实现燃烧过程建模及优化的重要手段.本文综述了各种计算智能算法在电站锅炉燃烧优化控制中研究成果,分别对其技术特点和不足进行了分析,并提出了燃烧优化技术的发展方向和前景,对从事该方面的研究人员有一定参考价值.     

Catalytic wall reactor: Catalytic coatings of stainless steel by VOx/TiO2 and Co/SiO2 catalysts

Catalytic wall (structured) reactors and structured supports are suitable to study the catalytic properties of nanosized materials. The coating of metallic (aluminum and stainless steel) plates by thin layers of active phase is presented in two cases, VO_x/TiO₂ and Co/SiO₂, catalysts used in the oxidative dehydrogenation (ODH) of propane and in Fischer–Tropsch synthesis (FTS) of clean fuels, respectively. The preparation of coated plates and their characterisation by various methods of physicochemical analysis are described. Both chemical and physical methods were used for coating. VO_x/TiO₂ layers were obtained by grafting of Ti (on Al or stainless-steel plates) and V (on TiO₂) alkoxides and use of sol–gel media or suspension. A silica primer was deposited (on stainless-steel plate) by plasma-assisted chemical vapour deposition (PACVD) onto which Co oxide and silica were coprecipitated from sol–gel. The catalytic experiments in the respective reactions were carried out in special plate reactors and compared with those of catalytic powders. The study shows that the coating of a metallic substrate by a catalyst is not straightforward and requires specific studies dealing with both chemistry (chemical affinity between substrate and catalytic layers) and catalytic engineering (catalytic performance in taylor-made reactors).     

丙碳脱碳溶剂的改进研究

介绍一种由丙碳、叔胺和少量活化剂构成的复合溶剂的开发，并详细地测定了不同压力和操作工况下，这种复合溶剂对ＣＯ２的吸收和解吸性能，以及溶剂的缓蚀性能和抗氧化性能．实验证明这种复合溶剂与纯丙碳相比，具有吸收容量大、速率快、脱碳净化度高、对设备无腐蚀等特点，对改进现行的丙碳脱碳工艺具有应用价值．     

Aromatization of n-butane over new LD-HBS catalysts. Effect of the gallium oxide support

It is shown that even pure quartz, other silicas or aluminas can enhance the aromatization activity of a ZSM-5 zeolite. Incorporation of gallium oxide onto these supports increases further the production of aromatics. The use of supported gallium oxide co-catalyst obtained by co-evaporation of a colloidal silica and a Ga salt has led to extremely high aromatization performance for the hybrid catalyst.     

Polymer electrolytes

Summary The room temperature conductivity of lithium salts dissolved in polyethylene oxide, proposed as polymer electrolytes, is shown to decrease drastically upon storage. The crystallization process, which is responsible for that ageing, can be blocked, if two further components are added : an elastomer copolymer butadiene-acrylonitrile and a macromer of polyoxyethylene. In addition, a crosslinking process must be carried out.     

网格环境下基于传输代价的副本优化策略*

在深入分析影响副本策略性能的各种因素的基础上,将多种因素和传输代价联系起来进行建模,提出一种副本优化策略。优化策略基于传输代价,综合考虑文件访问次数、大小、存在时间等多种因素,并充分利用文件访问次数的集合特征,提供了一个动态、全局的副本管理方法。在网格仿真器OptorSim中对基于传输代价的优化策略进行了实现和评估分析。实验分析证明,优化后的副本策略较现有策略有明显优势。     

AM60镁合金方向盘骨架压铸充型过程数值模拟

利用仿真软件FLOW-3D,对镁合金汽车方向盘骨架进行模拟.使用正交实验分析方法确定了压射速度、模具温度、浇注温度改变时压铸件产生缺陷百分比的变化.进行多组正交试验后,在优化的工艺参数下,观察液态镁合金充型及凝固过程中流场和温度场的分布情况,预测缺陷出现的部位,以寻求最佳的工艺参数,从而使铸造工艺和模具的设计得到了优化.模拟结果表明：最优的压射速度应为2.34m/s,模具初温为220℃,浇注温度为700℃,能达到最佳充型效果.     

基于构件的高校科研管理系统设计与实现

本文对当前高校科研管理系统的现状进行了分析,结合现代高校在信息化过程中所遇到的具体问题和需求,通过应用软件构件技术来提高系统的可适应性,设计和实现了该教务管理系统。