Gram Matrices of Mixed-State Ensembles

International Journal of Theoretical Physics - Gram matrices arise naturally in the consideration of pair-wise overlap of a family of vectors or quantum pure states, and play an important role in...     

Analysis of competitive chemostat models with the Beddington–DeAngelis functional response and impulsive effect

In this paper, we introduce and study a competitive system with Beddington–DeAngelis type functional response in periodic pulsed chemostat conditions. We investigate the subsystem with substrate and one of the microorganisms and study the stability of the periodic solutions, which are the boundary periodic solution of the system. The stability analysis of the boundary periodic solution yields an invasion threshold. By use of standard techniques of bifurcation theory, we prove that above this threshold there are periodic oscillations in substrate and one of the microorganism. Further, we prove that the system is permanent if the impulsive period less than some critical value. Therefore, our results are valuable for the manufacture of products by genetically altered organisms.     

N2O分解反应的动力学-Monte Carlo模拟

N2O是一种大气污染物，许多金属氧化物能使它发生分解反应，生成N2和O2．因此，N2O的催化分解反应很早就引起了研究者的兴趣[1]．传统的动力学着重去研究反应速率和一些反应参数，如温度、压力、组成等的关系，往往忽视催化表面的性质，从而使速率方程变得十分复杂．Kobayashi等人利用过渡应答法研究了N2O分解反应的动力学，计算了两个基元步骤的速率常数，但没有给出表面物种浓度变化的更进一步的信息[2]．近年来，MonteCarlo方法在研究表面反应机理和动力学方面已经取得了一些成功[3，4]．我们曾用MonteCarlo方法研究了N2O催化分解…     

表面扩散的Monte Carlo初探

利用ＭｏｎｔｅＣａｒｌｏ方法模拟了理想表面和分形表面上的扩散过程；通过模拟可以发现，表面扩散系数不仅与表面浓度有关，而且还与扩散的时间、表面的几何形貌等有关。在表面覆盖度比较高时，表面扩散系数有一极大值。与理想表面相比，分形表面会使扩散系数减小。     

硫代反义寡聚核苷酸在线性聚丙烯酰胺-毛细管电泳中的分离行为

通过对硫代反义寡聚核苷酸在毛细管线性聚丙烯酰胺胶（LPA）中的电泳行为的研究，发现在10％浓度的LPA和100mmol/L Tris-borate及7mol/L尿素的缓冲溶液中（pH=8.2），这类被分析物质有着较好的分离效果和重现性，能使相差一个碱基的硫代反义寡聚核苷酸片断得到基线分离。非常适合用于对合成的反义寡聚核苷酸的定性分析并进一步应用于纯度测定。     

Metal–Organic Gels Derived from Iron(III) and Pyridine Ligands: Morphology,Self‐Healing and Catalysis for Ethylene Selective Dimerization

Metal‐organic gels showing potential application in catalysis have received much concern. In this work, we designed and synthesized two metal‐organic gels based on coordination between Fe^III and pyridine ligands at room temperature. The gels were characterized by X‐ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM) to reveal their assembly structures and morphologies, and it was found the metal‐organic gel derived from di‐topic ligand was composed of three‐dimensional network of nanofibers, while the gel derived from tri‐topic ligand was constituted of sponge‐like structure with amorphous phase. Rheological analysis showed the gel consisting of nanofiber networks displayed self‐healing property. The gels were used as catalysts for selective ethylene dimerization, and the optimum catalysis results of the gel with nanofibers reached the maximal catalytic activity of 1.48×10⁵ g/(mol Fe?h) with C₄ yield more than 90 %, whereas the sponge‐like gel only gave 38 % C₄ products at the same condition. The higher dimerization selectivity of the former Fe^III gel was attributed to its regular assembly structure and lower steric hindrance of the surface metal sites. Due to its catalytic activity, high selectivity and preparation simplicity, the Fe^III gel might be potentially applicable for the preparation of C₄ α‐olefins.     

1,3‐Dipolar cycloadditions of 9‐diazofluorenes and diphenyldiazomethane to 2‐acyl‐2H‐1,2,3‐diazaphospholes

A series of 2‐acyl‐2H‐1,2,3‐diazaphospholes 3 underwent ready 1,3‐dipolar cycloaddition reactions with 9‐diazofluorenes as the 1,3‐dipole, yielding the respective bicyclic phosphiranes 5 or trimers 7 depending on the reaction conditions employed. The reaction is believed to proceed via the formation of the [3+2]‐cycloaddition adducts followed by elimination of nitrogen from the cyclic azo moiety. In the case of 3c , the phosphatetraazabicyclooctadiene compound 6 has been isolated with no loss of nitrogen. Likewise, the dipolar cycloaddition reaction of diphenyldiazomethane with the >C?P‐ moiety as the 1,3‐dipolarophile gave phosphadiazabicyclohexenes 8 in 32–68% yields.     

Synthesis of 2-substituted indoles by iridium (III)-catalyzed CH functionalization of N-phenylpyridin-2-amines

A highly regioselective synthesis of 2-substituted indoles was realized through Ir(III)-catalyzed CH functionalization of N-phenylpyridin-2-amines followed by the reaction with sulfoxonium ylides and intramolecular cyclization under mild conditions. The reaction completed with broad range of substrate scopes and gave various 2-substituted indoles in up to 98% yields.     

NiW/γ-Al2O3加氢催化剂化学吸附性质的研究

采用脉冲色谱法测定了噻吩在硫化态NiW/γ-Al2O3催化剂上化学吸附过程中热力学函数的变化,并与噻吩加氢脱硫(HDS)反应活性进行了关联.结果表明,噻吩在硫化态NiW/γ-Al2O3催化剂上的吸附不能太强,催化剂中的Ni可以降低噻吩在催化剂表面上的吸附强度,增加HDS反应活性中心的数目.从H2在硫化态NiW/γ-Al2O3催化剂上吸附后的程序升温脱附实验结果发现,H2在硫化态催化剂上有两种吸附态,高温脱附所对应的吸附态与HDS反应有关.     

N2O分解反应中复杂动力学行为的模拟

在多相催化反应中，自ZO多年前第一次在实验中观察到反应的振荡现象以来，现已发现在许多催化反应中都存在振荡现象山．N。O分解是一个振荡反应问．我们在用MonteCarloMC）方法研究N20分解反应机理时，曾发现反应速率和表面覆盖度在一定条件下都会出现振荡现象＊．非统性理论的研究表明，体系内部只要存在非线性的相互作用就可能表现出一些复杂的动力学行为，如振荡和混饨等．N。O分解反应中的振荡行为，也是由于体系内部非线性相互作用的结果·本文用非线性动力学的方法研究N。O分解反应中表面氧覆盖度的振荡行为，发现振荡在一定条…