分子力场进展

分子力学（简称ＭＭ）是近年来化学家常用的一种计算方法。与量子力学从头计算和半经验方法相比，用分子力学处理大分子可以大大节省计算时间，而且，在大多数情况下，用分子力学方法计算得到的分子几何构型参数与实验值之间的差值可在实验误差范围之内。所以，分子力学是研究生物化学体系的有效和可行的手段。分子力学的核心是分子力场。本文介绍了分子力场的量子力学背景、分子力场和光谱力场之间的关系。分子力场的一般形式、分力     

表面限域掺杂提升高比能正极材料稳定性

Lithium ion batteries (LIBs) have broad applications in a wide variety of a fields pertaining to energy storage devices. In line with the increasing demand in emerging areas such as long-range electric vehicles and smart grids, there is a continuous effort to achieve high energy by maximizing the reversible capacity of electrode materials, particularly cathode materials. However, in recent years, with the continuous enhancement of battery energy density, safety issues have increasingly attracted the attention of researchers, becoming a non-negligible factor in determining whether the electric vehicle industry has a foothold. The key issue in the development of battery systems with high specific energies is the intrinsic instability of the cathode, with the accompanying question of safety. The failure mechanism and stability of high-specific-capacity cathode materials for the next generation of LIBs, including nickel-rich cathodes, high-voltage spinel cathodes, and lithium-rich layered cathodes, have attracted extensive research attention. Systematic studies related to the intrinsic physical and chemical properties of different cathodes are crucial to elucidate the instability mechanisms of positive active materials. Factors that these studies must address include the stability under extended electrochemical cycles with respect to dissolution of metal ions in LiPF₆-based electrolytes due to HF corrosion of the electrode; cation mixing due to the similarity in radius between Li⁺ and Ni²⁺; oxygen evolution when the cathode is charged to a high voltage; the origin of cracks generated during repeated charge/discharge processes arising from the anisotropy of the cell parameters; and electrolyte decomposition when traces of water are present. Regulating the surface nanostructure and bulk crystal lattice of electrode materials is an effective way to meet the demand for cathode materials with high energy density and outstanding stability. Surface modification treatment of positive active materials can slow side reactions and the loss of active material, thereby extending the life of the cathode material and improving the safety of the battery. This review is targeted at the failure mechanisms related to the electrochemical cycle, and a synthetic strategy to ameliorate the properties of cathode surface locations, with the electrochemical performance optimized by accurate surface control. From the perspective of the main stability and safety issues of high-energy cathode materials during the electrochemical cycle, a detailed discussion is presented on the current understanding of the mechanism of performance failure. It is crucial to seek out favorable strategies in response to the failures. Considering the surface structure of the cathode in relation to the stability issue, a newly developed protocol, known as surface-localized doping, which can exist in different states to modify the surface properties of high-energy cathodes, is discussed as a means of ensuring significantly improved stability and safety. Finally, we envision the future challenges and possible research directions related to the stability control of next-generation high-energy cathode materials.     

使用四乙基氢氧化铵作为有机模板剂和常规硅铝源直接合成SSZ-13沸石分子筛

使用四乙基氢氧化铵作为有机模板剂, 利用常规铝源和硅源而不需要高硅Y沸石作为起始原料, 同时加入适量的沸石晶种直接合成了SSZ-13沸石分子筛. 所合成的沸石产物结晶度好, 具有良好的水热稳定性, 并在氨选择性催化还原(NH₃-SCR)反应中显示出优异的催化性能, 为其在工业上广泛应用提供了可能.     

Sudden Change of Quantum Discord in Qutrit-Qutrit System Under Depolarising Noise

The effects of decoherence on quantum discord of two-qutrit system under the influence of multilocal, collective and global depolarising noises are investigated. Sudden change of quantum discord with the decoherence parameter and the initial state parameter occurs for the qutrits being coupled to multilocal or global depolarising noises. On the other hand, decoherence cannot induce sudden change of quantum discord when the system is collectively coupled to the depolarising noise. In addition, the local unitary transformation can alter the region in which the phenomenon of sudden change exists.     

Wetting process of electrolyte in high density Cu/Sn micro-bumps electrodepositing

Wetting process of electrolyte in high density Cu/Sn micro-bumps electrodepositing is reported in this paper. Three methods were adopted to enable electrolyte to permeate photo-etching micro-holes with high aspect ratio, including plasma treatment, adding wetting additive in electrolyte and mechanical action. Wettability of the samples with electrolyte was improved by the first two methods, according to contact angle and surface tension measurement. However, electrolyte still cannot reach up to the bottom of micro-hole. And then, electrolyte was subjected to mechanical action, including agitation and ultrasonic vibration. Under mechanical action, void free Cu/Sn micro-bumps fabrication was achieved in photo-etching micro-holes with depth of 60 μm and radius of 30 μm. At last, we proposed a model to show wetting process of electrolyte in photo-etching micro-holes.     

Density Functional Theory Study of the Interaction between Guanine and Catechin

The interacting patterns and mechanism of the catechin and guanine have been investigated with the density functional theory B3LYP method by 6‐31G* basis set. Fourteen stable structures for the catechin‐guanine complexes have been found which form two hydrogen bonds at least. The results indicate that the complexes are mainly stabilized by the hydrogen bonding interactions. At the same time, the number and strength of hydrogen bond play a co‐determinant parts in the stability of the complexes which can form two or more hydrogen bonds. Theories of atoms in molecules (AIM) and natural bond orbital (NBO) have been adopted to investigate the hydrogen bonds involved in all systems. The interaction energies of all complexes have been corrected for basis set superposition error (BSSE), ranging from ?38.86 to ?14.56 kJ/mol. The results showed that the hydrogen bonding contributes to the interaction energies dominantly. The corresponding bonds stretching motions in all complexes are red‐shifted relative to that of the monomer, which is in agreement with experimental results.     

亚硝基甲胺异构化的量子化学研究

此文用ＭＮＤＯ方法研究了亚硝基甲胺异构化反应的机理。