Ce-MCM-48介孔分子筛的合成、表征和催化性能

尝试以混合模板剂pH调节水热合成掺入铈的介孔分子筛CeMCM48,并采用X射线衍射、高分辨透射电镜、紫外可见漫反射、X射线荧光光谱、氮气吸附脱附测试手段对样品进行表征.结果表明,新合成的掺铈介孔材料仍保持立方介孔的有序结构,有序性及吸附性能得到改善.所合成的掺铈的立方介孔分子筛对环己烷的液相氧化反应的催化活性和选择性较高.CeMCM48催化环己烷氧化反应的转化率较MCM48催化的转化率提高了8.3%～14.2%,对主要产物的选择性提高了63.4%～68.8%.     

A genetic k-medoids clustering algorithm

We propose a hybrid genetic algorithm for k-medoids clustering. A novel heuristic operator is designed and integrated with the genetic algorithm to fine-tune the search. Further, variable length individuals that encode different number of medoids (clusters) are used for evolution with a modified Davies-Bouldin index as a measure of the fitness of the corresponding partitionings. As a result the proposed algorithm can efficiently evolve appropriate partitionings while making no a priori assumption about the number of clusters present in the datasets. In the experiments, we show the effectiveness of the proposed algorithm and compare it with other related clustering methods.     

高Verdet常数的Tb3+铝硼硅酸盐玻璃

本文研究了一种铝硼硅酸盐基质玻璃,通过加大单位体积的稀土离子浓度,并选择P值大的顺磁性Tb³⁺作为弗尔德常数贡献的主要离子,经反复试验研究,制定合理的熔制工艺,得到性能稳定的透明顺磁旋光玻璃。弗尔德常数V=-0.375/Oe·cm。是目前世界上弗尔德常数较高的磁旋光玻璃。     

Microcalorimetric study on expression of foreign genes in Bacillus thuringiensis

The thermogenic curves of the aerobic metabolism of the three strains of Bacillus thuringiensis B.t. A, B.t. B and B.t. C have been determined by using an LKB-2277 BioActivity Monitor. B.t. A was the host bacterium without foreign gene. B.t. B and B.t. C were constructed by transforming different foreign genes into the host B.t. A, respectively. B.t. B expressed erythromycin resistant gene, while B.t. C expressed both erythromycin resistant gene and tyrosinase gene. The heat flow rate of these strains is B.t. A> B.t. B >B.t. C. These results indicated that there is obvious interrelation between expression of foreign genes and heat flow rate of B.t. strains. This revised version was published online in August 2006 with corrections to the Cover Date.     

The p-Harmonic Heat Flow with Potential into Homogeneous Spaces

In this paper we prove the existence of global weak solutions of the p-harmonic flow with potential between Riemannian manifolds M and N for arbitrary initial data having finite p-energy in the case when the target N is a homogeneous space with a left invariant metric. Received March 17, 1999, Revised September 22, 1999, Accepted October 15, 1999     

Design, Synthesis and Characterization of a Novel Schiff Base Bis(iminoantipyrine) and Its Modified Electrode

ThedevelopmentandaPplicationofchemicallymodifiedelectrodescontinuetobeareasofvigorousresearchactivityl-2.Recently,complexatioswithorganicreagentsasmodifiersincarbonpasteelectrodeshavebeenemployedforanalyticaldeterminations3.Schiffbaseligands,however,havebeenscarcelyreportedasmodifierstodeterminemetalions'.Theprincipalcharacteristicrequiredforthesuccessfulconstr[lctionofamodifiedcarbonpasteelectrodeisthatthesolubilityofthemodifiermustbesoslightinthesolventsemployedthatitremainstablyincorporated…     

Signatures of reactive resonance: three case studies

 Recent advances in the study of short-lived reactive resonances are reviewed. Special emphasis is given to addressing the question of how reactive resonances might be observed in molecular beam scattering experiments. Three case studies are presented for simple triatomic systems that are believed to exhibit resonance phenomena: F + HD → D + HF, F + H₂ → H + HF, and H + HD → D + H₂. It is seen that reactive resonances do strongly influence collision observables, but in a different way for each case. At this stage, there does not appear to be a unique resonance signature that can be applied to all reactions. Received: 2 March 2002 / Accepted: 2 June 2002 / Published online: 17 October 2002 Acknowledgements. For their valuable input into the research discussed here, we are grateful to our collaborators, K. Liu, S.H. nk;Lee, F. Dong, D.E. Manolopoulos, D, Skouteris, X. Yang, S. Harich, D. Dai, and C.C. Wang. This work was supported by the National Science Foundation. Correspondence to: R. T. Skodje e-mail: skokje@spot.colorado.edu     

从强子动力学模型看高温条件下核物质的新相

从QHD-Ⅱ模型的拉氏量出发,在有限温度场论的框架下,引入核子有效质量和有效化学势,给出了热力学势的平均场结果,分析了状态方程,发现在高温区核物质存在一个新的相变,最后给出了相图.     

两点边值问题解的存在性

本文讨论两点边值问题解的存在性,在没有孤立性条件下,获得了不动点定理,作为应用实例,给出了反应扩散方程稳态解的存在性证明。     

Regioselective 1,2-Addition of Ti(IV)-enolate to α, β–Unsaturated Compounds

The nucleophilic addition to α, β-unsaturated carbonyl compounds is a fundamental C-C bond forming reaction in organic chemistry1. Since there are two reaction sites in the α, β–unsaturated carbonyl group, the regioselectivity of the nucleophilic addition (1, 2 vs. 1, 4 addition) is of primary importance when applying this type of reaction in organic synthesis. Factors that control the regioselectivity include the softness and hardness of the attacking nucleophiles2, solvent and temperatu…