与条形区域有关的双向单叶解析函数子类的系数估计

本文引入了条形区域内由Salagean算子刻画的解析函数新子类, 讨论了该函数子类的系数估计、Fekete-Szego不等式以及与该函数子类有关的双向单叶函数的系数估计, 所得结果推广了前人的一些工作.     

Effects of middle plane curvature on vibrations of a thickness-shear mode crystal resonator

We study the effects of a small curvature of the middle plane of a thickness-shear mode crystal plate resonator on its vibration frequencies, modes and acceleration sensitivity. Two-dimensional equations for coupled thickness-shear, flexural and extensional vibrations of a shallow shell are used. The equations are simplified to a single equation for thickness-shear, and two equations for coupled thickness-shear and extension. Equations with different levels of coupling are used to study vibrations of rotated Y-cut quartz and langasite resonators. The influence of the middle plane curvature and coupling to extension is examined. The effect of middle plane curvature on normal acceleration sensitivity is also studied. It is shown that the middle plane curvature causes a frequency shift as large as 10⁻⁸ g⁻¹ under a normal acceleration. These results have practical implications for the design of concave–convex and plano-convex resonators.     

ELECTRIC FIELD GRADIENT EFFECTS IN ANTI-PLANE PROBLEMS OF A CIRCULAR CYLINDRICAL HOLE IN PIEZOELECTRIC MATERIALS OF 6 mm SYMMETRY

We study electromechanical fields in the anti-plane deformation of an infinite medium of piezoelectric materials of 6 mm symmetry with a circular cylindrical hole. The theory of electroelastic dielectrics with electric field gradient in the constitutive relations is used. Special attention is paid to the fields near the surface of the hole.     

Electrocatalytic CO2 Reduction and H2 Evolution by a Copper (II) Complex with Redox-Active Ligand

The process of electrocatalytic CO₂ reduction and H₂ evolution from water, regarding renewable energy, has become one of the global solutions to problems related to energy consumption and environmental degradation. In order to promote the electrocatalytic reactivity, the study of the role of ligands in catalysis has attracted more and more attention. Herein, we have developed a copper (II) complex with redox-active ligand [Cu(L¹)₂NO₃]NO₃ (1, L¹ = 2-(6-methoxypyridin-2-yl)-6-nitro-1h-benzo [D] imidazole). X-ray crystallography reveals that the Cu ion in cation of complex 1 is coordinated by two redox ligands L¹ and one labile nitrate ligand, which could assist the metal center for catalysis. The longer Cu-O bond between the metal center and the labile nitrate ligand would break to provide an open coordination site for the binding of the substrate during the catalytic process. The electrocatalytic investigation combined with DFT calculations demonstrate that the copper (II) complex could homogeneously catalyze CO₂ reduction towards CO and H₂ evolution, and this could occur with great performance due to the cooperative effect between the central Cu (II) ion and the redox- active ligand L¹. Further, we discovered that the added proton source H₂O and TsOH·H₂O (p-Toluenesulfonic acid) could greatly enhance its electrocatalytic activity for CO₂ reduction and H₂ evolution, respectively.     

基于超分子晶体制备超细铂纳米颗粒用于催化加氢硝基苯

由于纳米催化剂的独特催化活性,因而开发稳定的超细纳米催化剂的制备方法引起了广大科研工作者们的关注.然而,复杂的合成过程和结构的不稳定性己经成为纳米催化剂研究和实际应用的瓶颈.本工作通过原位还原氯铂酸和十甲基五元瓜环(Me10CB[5])构筑的超分子晶体材料,成功制备了粒径尺寸约为3.0 nm的超细铂纳米粒子.Me10C...     

光催化选择性合成有机物

光催化反应比传统催化反应条件温和,不但能利用太阳能作为光源,同时,也避免了一些强氧化剂、危险还原剂和有毒物质的使用,极大地满足了人们对能源和环境的要求。通过优化光催化体系可以实现对目标产物的选择性合成,从而为有机合成提供一种绿色、节能的途径。本文综述了近年来光催化选择性合成有机物的催化剂类型,影响选择性因素和提高选择性的途径,重点就光催化材料的晶型、催化剂的合成与表面修饰、溶剂种类、催化条件等因素在聚合反应、芳香族的羟基化反应、胺的氧化反应、烯烃环氧化反应、羰基反应选择性合成有机物方面作一评述,并对光催化在选择性合成有机物的研究和进展进行了展望。     

Effects of DNA mismatches on binding affinity and kinetics of polymerase-DNA complexes as revealed by surface plasmon resonance biosensor

In this study, surface plasmon resonance (SPR) biosensor techniques were used to obtain quantitative information on the kinetics of the DNA and polymerase I (Klenow fragment) interaction. DNA duplexes containing different base compositions at the binding site were immobilized on the SPR sensor surface via biotin-streptavidin chemistry and the subsequent binding of the polymerase was measured in real time. Various kinetic models were tested and a translocation model was shown to provide the best fit for the binding and dissociation profiles. The results revealed that the enzyme binds to DNA at both the polymerase and the exonuclease domains with different association and dissociation rates as well as affinity constants, depending on the presence of mismatches near the primer 3'-end. Introduction of unpaired bases increases the DNA binding affinity towards the exonuclease domain and promotes the translocation of DNA from the polymerase site to the exonuclease site. The results also demonstrated that SPR biosensors may be used as a sensitive technique for studying molecular recognition events such as single-base discrimination involved in protein-DNA interaction.     

3D纸基模型表面亮度预测研究

纸基模型表面亮度感知是整体色貌感知的重要组成,亮度感知的准确性、快捷性直接影响到纸基模型整体外貌的视觉感知。本文通过对3D纸基模型表面亮度测量,实现3D纸基表面在不同角度、不同阶调时的亮度预测。首先,通过设计的纸模测量角度架,可以方便快捷地调整纸基表面角度,然后,确定测量角度取样间隔为5°,纸模表面角度为5°~85°,依次测量,最后,设计四色表面梯尺,青色、品色、黄色、黑色在不同纸基表面和不同阶调下,利用辐射亮度计对其表面亮度值进行测量。利用最小二乘法建立亮度与纸基表面角度、阶调之间的关系模型,并对模型优劣程度进行检验。结果表明,本预测模型可以快速准确地对任意角度3D纸基表面进行亮度预测,获取3D纸基模型表面的亮度。     

Properties of gel polymer electrolytes based on poly(butyl acrylate) semi-interpenetrating polymeric networks toward Li-ion batteries

A new type of gel polymer electrolyte (GPE) based on poly(butyl acrylate) (PBA) semi-interpenetrating polymer networks (IPNs) and polyvinylidene fluoride (PVDF) was prepared in different molar ratios ranging from 1:0.5 to 1:1. A series of structure characterizations of PBA/PVDF had been measured using FTIR, XRD, and SEM. The electrolyte uptake test revealed that when the semi-IPNs were swollen with the commercial liquid electrolyte solutions, they showed an outstanding electrolyte uptake of 120% with a chemically cross-linked structure. All results indicated that the GPE exhibited the best performance when the molar ratio of BA and PVDF was 1:0.5. The prototype cell assembled with LiFePO₄ as cathode, lithium metal as anode, and GPE as the electrolyte as well as separator retained 94% of its initial specific capacity after 100 charge-discharge cycles, showing an excellent cycling stability and a high electrochemical window (up to 4.5 V against Li⁺/Li) at room temperature. Compared with the liquid electrolyte, the GPE exhibited a similar stable cycling performance and was suitable for practical application in Li-ion batteries.