Luminescence Characterization of Mg Doped Y2O2S:Ti Long Afterglow Phosphor

Y1.94-xMgxO2S:0.06Ti (0≤x≤0.10) phosphors with long afterglow were synthesized by solid state reaction route. The photoluminescence spectra, decay curves, thermoluminescent spectra and chromaticity coordinate curves were investigated. The results show that the luminescence intensity of Y1.94-xMgxO2S:0.06Ti (0≤x≤0.10) phosphors decrease gradually with increasing Mg2 ion content, and the shape of luminescence spectra and chromaticity coordinate change as well. Furthermore, two thermoluminescent peaks in single Ti-doped Y2O2S sample are found at 91.8 and 221.5 ℃, respectively. Nevertheless, significant different spectra were found for the Mg, Ti co-doped Y2O2S samples that three thermoluminescence peaks appear at 52.3, 141.7 and 226.8 ℃, respectively. These results indicate that the co-doped Mg ion changes the inherent trap depth of single Ti-doped Y2O2S:Ti phosphor, and induces simultaneously a new trap level in the Y1.94-xMgxO2S:0.06Ti phosphor. Based on the analysis of thermoluminescent spectra, photoluminescent spectra, decay curve and crystal structure defect, it was proposed that the varied structure defect and introduced new trap level by the doped Mg2 ions should be responsible for reducing luminescence intensity and varying color in the Y1.94-xMgxO2S:0.06Ti phosphor.     

Kinetic investigation of the carbothermal reduction of an Iranian clay

The kinetics of the carbothermal reduction of clay under argon atmosphere has been investigated by the X-ray diffraction method. The clay-carbon (excess) mixture was formed into 2 cm diameter disks of different thicknesses. Experimental data evidences the significant effect of sample thickness on the reaction rate at 1400 °C. Decreasing thickness promotes mullite dissociation and formation of SiC and alumina powders. Mathematical modeling of the reaction system showed the gas diffusion in the Knudsen regime through the pellet to be the rate controlling step. Diffusivity of CO and reacted core tortuosity factor have been calculated.     

水对植物纤维水泥复合板生产的影响

研究了水对植物纤维水泥复合板性能的影响。选择合适的水分可以提高板材静弯曲强度,减小板材变形。     

环境因子的定义及研究现状

从普遍接受的三个基本假设出发，讨论环境因子的定义和失效机理不变的约束条件，重点综述环境因子的研究现状和常用方法，并探讨引入反应论模型解决环境因子预测问题的可能途径。     

Morphology of intermetallic compounds formed between lead-free Sn-Zn based solders and Cu substrates

The morphologies of intermetallic compounds formed between Sn-Zn based solders and Cu substrates were investigated in this study. The investigated solders were Sn-9Zn, Sn-8.55Zn-0.45Al, and Sn-8.55Zn-0.45Al-0.5Ag. The experimental results indicated that the Sn-9Zn solder formed Cu₅Zn₈ and CuZn₅ compounds on the Cu substrate, while the Al-containing solders formed the Al_4.2Cu_3.2Zn_0.7 compound. The addition of Ag to the Sn-8.55Zn-0.45Al solder resulted in the formation of the AgZn₃ compound at the interface between the Al_4.2Cu_3.2Zn_0.7 compound and the solder. Furthermore, it was found that the cooling rate of the specimen after soldering had an effect on the quantity of AgZn₃ compound formed at the interface. The AgZn₃ compound formed with an air-cooling condition exhibited a rougher surface and larger size than with a water-quenched condition. It was believed that the formation of the AgZn₃ compound at the interface occurs through heterogenous nucleation during solidification.     

吡啶型铝酸盐离子液体催化β-甲基萘歧化反应

研究了三氯化铝-氯化丁基吡啶(n-BPC-AlCl3)离子液体催化β-甲基萘歧化合成2，6-二甲基萘(2，6-DMN)反应。通过正交试验，考察了反应温度、时间、BPC—AlCl3离子液体酸强度及催化剂用量对β-甲基萘歧化反应的影响。实验结果表明，BPC—AlCl3酸性离子液体对β-甲基萘歧化反应具有良好的催化活性和较好的2，6-二甲基萘选择性。在120℃，AlCl3／BPC的摩尔比为4：1，催化剂质量分数12％，反应时间为3．5h的条件下，反应转化率为29．0％，2，6-DMN的选择性为32．5％。     

端基封闭法合成双环戊二烯改性不饱和聚酯

研究端基封闭法合成双环戊二烯（ＤＣＰＤ）改性不饱和聚能工艺条件对产品性能的影响。研究结果表明，合成反应的最佳工艺条件为总酸酐：丙二醇：ＤＣＰＤ＝１：１．１：０．１─０．１６；封端反应温度１３０─１４０℃催化剂量为总重量的０．０２％─０．０３％；聚酯酸值５０ｍｇｋＯＨ·ｇ￣（－１）时滴加ＤＣＰＤ，滴加时间控制在１─２小时；加成反应时间为２小时左右。     

New intramolecular effect observed for polyesters: An anomeric effect

A series of polyesters was prepared to evaluate hydrolytic stability as a function of cyclohexyl dibasic acid content. The three cyclohexyl dibasic acids: 1,2; 1,3; and 1,4 were formulated into polyesters with two glycols. The proportion of cis and trans isomers was evaluated via ¹H NMR. The hydrolytic stability of short chain polyesters was evaluated in an acetone/water mixture which solubilized the polyesters to mimic oligoester behavior within a thermosetting polyester coating environment. The rate of hydrolysis was monitored by acid titration and corroborated by GPC. Surprisingly, 1,2-cylohexyl diacid-based polyesters were robust, and 1,3-cyclohexyl diacid-based polyesters were the most susceptible to hydrolysis. Evidently, a 1,2-anchimeric effect for cyclohexyl dibasic acid polyesters was not an important consideration, while the 1,3-cyclohexyl ester interaction was. Consequently, an anomeric effect was proposed. Presented at the 81st Annual Meeting of the Federation of Societies for Coatings Technology, November 12–14, 2003, in Philadelphia, PA.     

大庆蜡油在酸性催化剂上反应机理的研究

以大庆蜡油为原料，采用两种不同类型的催化剂，在流化床反应器实验装鬣上进行催化裂化反应。结果表明，大庆蜡油在酸性催化剂上反应所产生的干气组成与高烯烃催化裂化汽油相同，干气的产生主要是单分子裂化反应所造成的。从干气产率、组成以及液化气组成可以看出，大庆蜡油在不同类型的催化剂上明显地表现出裂化反应类型的差异。     

Dissolution kinetics of ulexite in acetic acid solutions

Ulexite is an important boron mineral used for the production of boron compounds. The aims of this study are to examine the dissolution kinetics of ulexite in acetic acid solutions, and to present an alternative process to produce boric acid. In order to investigate the dissolution kinetics of ulexite in acetic acid solutions, the concentration of solution, reaction temperature, solid-to-liquid ratio, and particle size were selected as experimental parameters. It was determined that the dissolution rate of ulexite increased with increasing solution concentration and temperature and decreasing particle size and solid-to-liquid ratio. The activation energy of the process was found to be 55.8 kJ/mol.