A new infinite inorganic [n]catenane from silver and bis(2-methylimidazolyl)methane ligand

A new type of 1D infinite inorganic [n]catenane framework was self-assembled by silver nitrate and bis(2-methylimidazolyl)methane, while a comparatively one-dimensional zigzag cationic chain was generated by AgNO(3) and bis(imidazol-1-yl)methane.     

Crystal structure of a tetranuclear nickel (II) complex of a 24-membered Schiff base macrocyclic ligand

The tetranuclear nickel(II) complex of 24-membered Schiff base macrocyclic ligand has been prepared by template condensation of two molecules 2,6-diformyl-4-chlorophenol with two molecules 2,6-bis(aminomethyl)-4-methylphenol monohydrochloride in methanol solution in the presence of excess nickel(II) acetate and sodium acetate/ acetic acid. The tetranuclear nickel(II) complex contains neutral molecules of composition LNi₄(CH₃COO)₂(OH)(CH₃O H OCH₃), together with two molecules methanol in the lattice, and it possesses a monoclinic space group C2/c, with a = 21.5053(18) Å, b = 8.8782(7) Å, c = 25.374(2) Å, = 93.7830(10)°, and D _calc = 1.631 mg/m³ for Z = 8. The crystallographic data show that the macrocyclic ligand binds four nickel(II) ions at the corners of an approximate square with a ₄ hydroxo group bound equally to four metals.     

Origin of Oxide sensitivity in gold-based catalysts: a first principle study of CO oxidation over Au supported on monoclinic and tetragonal ZrO2

The catalytic performance of Au/oxide catalysts can vary significantly upon the change of oxide species or under different catalyst preparation conditions. Due to its complex nature, the physical origin of this phenomenon remains largely unknown. By extensive density functional theory calculations on a model system, CO oxidation on Au/ZrO2, this work demonstrates that the oxidation reaction is very sensitive to the oxide structure. The surface structure variation due to the transformation of the oxide phase or the creation of structural defects (e.g., steps) can greatly enhance the activity. We show that CO oxidation on typical Au/ZrO2 catalysts could be dominated by minority sites, such as monoclinic steps and tetragonal surfaces, the concentration of which is closely related to the size of oxide particle. Importantly, this variation in activity is difficult to understand following the traditional rules based on the O2 adsorption ability and the oxide reducibility. Instead, electronic structure analyses allow us to rationalize the results and point toward a general measure for CO + O2 activity, namely the p-bandwidth of O2, with important implications for Au/oxide catalysis.     

键能的分子轨道理论研究2: 键能与Mulliken布居对键强度的 判断的比较

用键能E~A~B和Mulliken布居对化学键强度的判别进行了分析比较。结果表明,键能判据比Mulliken布居判据所得结论更符合实际情况。作为衡量原子间化学键强度的尺度,不仅应考虑原子轨道间的布居因素,还应考虑分子轨道(或原子轨道)的能量因素。     

Structure and Connectivity Analysis of Financial Complex System Based on G-Causality Network

The recent financial crisis highlights the inherent weaknesses of the financial market. To explore the mechanism that maintains the financial market as a system, we study the interactions of U.S. financial market from the network perspective. Applied with conditional Granger causality network analysis, network density, in-degree and out-degree rankings are important indicators to analyze the conditional causal relationships among financial agents, and further to assess the stability of U.S. financial systems. It is found that the topological structure of G-causality network in U.S. financial market changed in different stages over the last decade, especially during the recent global financial crisis. Network density of the G-causality model is much higher during the period of 2007-2009 crisis stage, and it reaches the peak value in 2008, the most turbulent time in the crisis. Ranked by in-degrees and out-degrees, insurance companies are listed in the top of 68 financial institutions during the crisis. They act as the hubs which are more easily influenced by other financial institutions and simultaneously influence others during the global financial disturbance.     

高校大型仪器设备开展科普教育的探索与实践——以电子显微镜为例

大型仪器设备是高校引领原始创新和科技进步的核心力量,挖掘大型仪器设备的科普内涵,是新时代高校开展科普教育、服务社会的创新举措。阐述了大型仪器设备开展科普教育的现实意义,分析了大型仪器设备开展科普教育的实现途径,并以电子显微镜为例,探索了大型仪器开展科普教育的可行性。     

键能的分子轨道理论研究Ⅱ.键能与Mulliken布居对键强度的判断的比较

用键能EAB和Mulliken布居对化学键强度的判别进行了分析比较.结果表明,键能判据比Mulliken布居判据所得结论更符合实际情况.作为衡量原子间化学键强度的尺度,不仅应考虑原子轨道间的布居因素,还应考虑分子轨道(或原子轨道)的能量因素.     

Experimental investigation of backward wave oscillator with low magnetic field

A backward wave oscillator (BWO) is introduced in the paper. On the accelerator of Sinus-700, it is experimentally investigated. Under the condition that the electron energy is 740keV, the beam current is 7kA and the guiding magnetic field is at 0.68T, the performance of 1.15GW microwave output power at. 9.1GHz microwave frequency with 22ns pulse width and 22% conversion efficiency are reached.     

DFT Study on the Os^＋-catalytic Reduction Reaction of N2O with H2 in the Gas Phase

The Os+-catalytic reduction of N2O by H2 in gas phase has been theoretically investigated with B3LYP method.The reaction mechanisms on the sextet and quartet surfaces were found to be similar.The calculated sextet potential energy profiles show that the two reactions involved in the catalytic cycle,Os+ + N2O → OsO+ + N2 and OsO+ + H2 → Os+ + H2O,have barriers of 28.3 and 123.3 kJ/mol,respectively.In contrast,the reactions on the quartet surfaces are energetically much more favorable.These results rationalize the experimentally observed low catalytic reactivity of sextet(ground-state) Os+.Further,the crossing between the sextet and quartet surfaces are also suggested and qualitatively discussed.