Monolayer dispersion thresholds and threshold effect displayed by supported catalysts

The principle of spontaneous monolayer dispersion holds that active components of many supported catalysts will disperse spontaneously onto the surface of the carrier. The monolayer dispersion threshold of the active component on the surface of the carrier can be measured by X-ray diffraction phase-quantitative extrapolation method, etc. By measuring the monolayer dispersion threshold, beneficial information on the surface structure and dispersion of supported catalysts can be obtained, and the optimal preparative processing conditions of the catalysts can be chosen. The proportion of the active component of many supported catalysts can be optimized while its monolayer dispersion threshold is observed. Mutation values of many physicochemical properties of supported catalysts are related to monolayer dispersion thresholds; the threshold effect on catalysts is apparent, and the proposal regarding the threshold effect provides instruction for the research on catalysts. __________ Translated from Chemistry, 2007, 70(12): 900–907     

On a mutualism model with feedback controls

We propose and study a mutualism model with feedback controls. By applying a new differential inequality, we show that the conditions which ensure the permanence of the system are the same as that of the model without feedback controls, which means that the feedback control variables have no influence on the persistent property of the system. Our results not only improve but also complement some existing ones.     

单圈共轭图的最小广义Randic指标R-1

图G的广义Randic指标定义为Rα=Rα（G）=∑uv∈E（G）（d（u）d（v））^α,其中d（u）是G的顶点u的度,α是任意实数．本文确定了单圈共轭图的广义Randic指标R-1的严格下界,并刻划了达到最小R-1的极图,这类极图还是化学图．     

TiO2调变对MoO3／γ—Al2O3和CoO—MoO3／γ—Al2O3催化性能的影响

采用气相流动吸附法制备ＴｉＯ２／γ－Ａｌ２Ｏ３复合载体，用浸渍法其担载一定量的ＭｏＯ３或ＣｏＯ－ＭｏＯ３。用ＸＲＤ、ＬＲＳ和ＴＰＲ等技术，考察了Ｍｏ或Ｃｏ－Ｍｏ催化剂的表面结构和还原性能，并有和中压固定床反应装置测定催化剂的噻吩加氢脱硫和环己烯加氢的活性。     

TEMPO存在下丙二腈对苯乙烯聚合的加速作用研究

在少量丙二腈存在下,苯乙烯在稳定自由基TEMPO作用下的聚合速率显著增加,分子量分布较窄,且随转化率增大而增大,具有活性聚合特征.丙二腈与TEMPO的摩尔比在4:1时加速效果较好,在125℃下聚合1h转化率可达到70%,分子量可达到105,且反应温度降低到110℃.¹HNMR分析表明,丙二腈在反应中起催化剂作用,通过削弱碳氮键可以提高转化速度,还可明显降低聚合温度.     

双极膜技术在无机盐工业中的应用

介绍了近十年来双极膜技术的最新研究成果及其在无机盐产酸、产碱工艺中的应用。将双极膜技术应用于氯碱工业中,在阳极上,以析氧反应替代传统的析氯反应。将双极膜电解槽与现行的氯氢离子膜电解槽连用,可构建出新的氯氢平衡的体系,以实现氯碱厂中析氯量的有效控制。在钾盐生产的工艺中联产硫酸和烧碱。     

柚皮苷印迹β-环糊精聚合物的制备及性能研究

以柚皮苷(NG)为印迹分子, β-环糊精为功能体, 六亚甲基二异氰酸酯为交联剂, 采用乳液聚合法制备了对NG具有特定识别能力的吸附材料: 棒状印迹聚合物. 扫描电镜及比表面分析仪测试结果表明印迹聚合物具有较大的孔隙及比表面积|红外及核磁共振谱研究证实了识别位点来自β-环糊精与NG羟基间的氢键作用. 采用平衡吸附实验方法研究了聚合物的吸附性能和选择性能. 实验结果表明, 棒状印迹聚合物(RMIP)对NG具有较高的亲和性和选择性. Scatchard分析表明, MIP在识别NG过程中存在2类结合位点: K_D1＝0.016 mmol/L, B_max1＝15.31 μmol/g, K_D2＝0.24 mmol/L, B_max2＝98.41 μmol/g. 当NG浓度为 0.02 mg/mL时, MIP及相应NIP对 NG的分配系数 K_{D 分别为4.38和2.86, 印迹因子α为1.53.}     

Permanence of a nonlinear integro-differential prey-competition model with infinite delays

A nonlinear integro-differential prey-competition model with infinite delays is investigated. Sufficient conditions are obtained for the permanence of the system.