Structure and electrochemistry of 4,4'-dithiodipyridine self-assembled monolayers in comparison with 4-mercaptopyridine self-assembled monolayers on Au(111)

4,4'-Dithiodipyridine (PySSPy) monolayers on Au(111) were investigated by cyclic voltammetry, X-ray photoelectron spectroscopy (XPS) and in situ scanning tunneling microscopy (STM). The studies were performed in solutions of different anions and pHs (0.1 M H2SO4, 0.1 M HClO4, 0.1 and 0.01 M Na2SO4, 0.1 and 0.01 M NaOH). The cyclic current-potential curves in H2SO4 show current peaks at about 0.4 V, which are absent for all other electrolytes at this potential. The XPS data suggest that PySSPy adsorbs via the S endgroup on the gold surface and the S-S bond breaks during adsorption. From the chemical shift of the N(ls) peak, it is concluded that in acidic media the self-assembled monolayer (SAM) is fully protonated, whereas in basic solution it is not. The pKa is estimated to be 5.3. STM studies reveal the existence of highly ordered superstructures for the SAM. In Na2SO4 and H2SO4, a (7 x mean square root of 3) structure is proposed. However, whereas in Na2SO4 solutions the superstructure does not change with potential, in 0.1 M H2SO4 the superstructure is observed only negative of the current peak at +0.4 V. At more positive potentials, the film becomes disordered. The results are compared to those for 4-mercaptopyridine (PyS) SAMs. XPS experiments and current-potential curves indicate that both molecules adsorb in the same manner on Au(111), that is, even in the case of PySSPy the adspecies is PyS. The STM results, however, call for a more subtle interpretation. While in Na2SO4 solutions the observed superstructures are the same for both SAMs, markedly different structures are found for PySSPy and PyS SAMs in 0.1 M H2SO4.     

热容激光器激光介质的热力学数值模拟

为模拟激光介质的温度、热应力的分布和变化,建立了激光介质热力学计算模型.该模型从激光介质的瞬态导热微分方程出发,得到沿纵向的热沉积功率密度,并将其作为该微元段的热载荷,加载到该微元段的泵浦区.考虑热容值、热导率、热膨胀系数和弹性模量等与温度的关系,得到激光介质的温度分布和变化,以及热应力的分布和变化.为热容激光器的实验和设计提供参考依据.     

Argon glow discharge and vapor-phase grafting of vinyl monomers on wettability of polyethylene

Argon glow discharge-induced vapor-phase grafting of vinyl monomers containing various polar pendant groups onto PE films was investigated. Relationships between the enhanced wetting properties and the level of grafting, the types of pendant groups, and the surface topographical features were established. Improved wettability of the grafted PE surfaces is attributed to both the increased surface polarity and topographical features. On AA-grafted PE surfaces with optimal wettability, microcracks, with depths of 130 ∼ 250 nm, lengths over 10 µm, and widths between 1.5 and 6.0 µm, are proved to be a topographical feature necessary for improved wettability. With sufficient microcracks, grafting with vinyl monomers containing carbonyl groups, i.e., carboxyl, aldehyde, and ketone groups, improved surface wetting more than grafting with those containing either hydroxyl and epoxy groups. The acquired wettability of vinyl monomer-grafted PE surface is attributed to the physicochemical synergism between the microcracks and the polar groups. © 1997 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 35: 1145–1159, 1997     

2020年先进能源材料与器件国际大会学术会议综述

来自国内外150多所高校和企业的近400名专家学者和研究生代表出席了本次会议. 会议围绕新能源的先进电化学储能材料与器件展开研讨, 所涉及的储能体系包括了锂离子电池、锂硫电池、超级电容器及新型二次电池等. 本次会议为推动先进能源材料与器件领域的发展提供了一个良好的学术交流平台, 大大提升了研发人员对新能源行业的发展动态、市场需求以及前沿工艺技术的深层次了解, 对于推动基础研究成果和产业化应用的紧密结合起到了积极的作用.     

Investigation on Normal Dynamic Contact Characteristics of Mechanical Interface of Machine Tools

The dynamic contact characteristics of mechanical interface significantly impact the performance of machine tools.The static contact behaviors of mechanical interface have been studied.However,most mechanical interfaces are exposed to dynamic load.It is necessary to study the dynamic contact characteristics of mechanical interface.A normal dynamic microcosmic contact model is built using the statistical method,and the interactional effects of adjacent asperities are considered.The influences of the normal preload,vibrational frequency and displacement amplitude on normal contact stiffness and damping of mechanical interface are revealed.The predicted contact stiffness and damping of mechanical interface are verified by a series of simulations and experiments.     

实数型格子气模型及方柱绕流的模拟

在4Bits的HPP格子气模型基础上提出了用实数表示节点每一速度方向的粒产密度的实数型HPP模型,建立了粒子碰撞的运算关系式(代替碰撞规则),用此方法对方柱绕流问题进行了计算并介绍了边界条件的处理方法,计算结果较好地反映了真实流动特性。     

快淬NdFeB磁粉颗粒度对聚合物粘结NdFeB磁体永磁性能的影响

研究了快淬ＮｄＦｅＢ永磁粉颗粒及其分布对聚合物粘结ＮｄＦｅＢ永磁材料性能的影响。快淬Ｎｄ－ＦｅＢ永磁粉颗凿大小及其分布显著地影响聚合物结ＮｄＦｅＢ永磁材料的磁性能。适当尺寸的快淬ＮｄＦｅＢ磁粉组合可获得高的结ＮｄＦｅＢ永磁帝主要是由于快淬ＮｄＦｅＢ磁粉硬度高,呈鳞片状,其尺雨越大越难获得高密度,但尺寸太小又将破坏磁粉的结构,导致磁性能恶化。     

Orientation of Antibodies on a 3-Aminopropyltriethoxylsilane-Modified Silicon Wafer Surface

An antibody can be specifically oxidized with periodate (NaIO₄) on the carbohydrate side chains at its C-terminal. Rabbit anti-hepatitis B surface antigen (anti-HBsAg) IgG antibodies were bound to the silicon wafer surface by covalent bonds between aldehydes generated on the carbohydrate side chains of the antibodies and the reactive amine groups of 3-aminopropyltriethoxylsilane(APTES)-modified silicon wafer surfaces. A control experiment was also performed by direct attachment of antibodies to glutaraldehyde-treated silicon surfaces. Two different coupling antibody strategies were investigated in this paper. Atomic force microscopy was used to observe the orientation of the site-directed and random attachment of rabbit anti-HBsAg IgG antibodies and the conservation of their antigen-binding capacity (AgBC) was assessed using an enzyme immunoassay (EIA).     

正磷酸硅晶相形成温度与配酸比的研究

4,4-二甲基二氧六环-1,3(DMDO)催化制异戊二烯P₂O₅-SiO₂(0.6)催化剂,高温长时间活化能形成Si₃(PO₄)₄,有良好的选择性.前文^[1]配酸比在0～2都可形成Si₃(PO₄)₄,0.8和1.2的选择率虽然不变,但DMDO转化率却明显下降,同时发现颗粒间粘接.     

冠醚配合物热力学性质的研究(Ⅶ)-碱金属与2,3-苯并-6-甲基-15-冠-5配位反应的量热滴定研究

用自制跟踪绝热式滴定量热计研究了新合成的2,3-苯并-6-甲基-15-冠-5在无水甲醇介质中与碱金属的配位反应。