一种校验带电粒子速度成像探测器的新方法

带电粒子(离子或者电子)速度成像技术可以精确测量带电粒子产物的速度分布和角分布,获得光谱级别分辨率的原子分子能级结构,广泛应用于光电离和光解离等分子反应动力学实验中.速度成像探测器的效率和信号相对强度对带电粒子速度分布信息的提取具有重要的影响.由于难以精确测量入射离子数,至今仍然没有直接校验速度成像探测器的方法报道.本文基于铷原子磁光阱搭建了一套离子速度成像实验装置,实现了入射离子数的精确测量及连续可调,并对冷原子的光电离过程、微通道板探测器采集的飞行时间信号、电荷耦合器件采集的荧光屏信号进行了校验,对可能影响速度成像信号相对强度的因素进行了检验.实验结果表明:当入射离子数低于1×105个/(100 ns)时,微通道板探测器的增益稳定,而荧光屏信号强度与入射其表面的电子数量的关系受荧光屏电压影响比较严重.同时,结果表明本方法可以有效校验带电粒子速度成像探测器的效率和信号的相对强度,对使用速度成像技术的实验具有一定的借鉴意义.     

Calculation of Electronic Structure of Zinc-Blende CdS

The linear-muffin-tin orbital method is used to study the electronic-energy-band structure of zinc-blende CdS. Incorporating the 4d states of Cd into the valence band gives substantially the main-valenceband width, and yields valenceband features in agreement with the experiment. The calculated equilibrium lattice constant is in accord with the measured result. The fundamental band gap is found to be direct at T point and the value is about 1.21 eV. The band structure calculation shows that the present results are in good agreement with experiments and other calculations.     

半规管内流体动力学问题

对单根半规管内流体动力学的Buskirk模型给出了一个对任意模型参数ε均成立的高精度解析解 ,该解不仅包括了Buskirk等人的所有结果 ,而且包含了 3种可能的动力学响应模式 ,与目前已有实验结果更加吻合 ,为定量了解半规管内流体动力学问题 ,特别是流体动力响应 ,提供了可靠的理论依据 .为了求出速度分布 ,根据复分析的理论 ,给出了一种非标准化的复反演方法 .     

One-pot tuning of Au nucleation and growth: from nanoclusters to nanoparticles

We describe a simple and effective method to obtain colloidal surface-functionalized Au nanoparticles. The method is primarily based on irradiation of a gold solution with high-flux X-rays from a synchrotron source in the presence of 11-mercaptoundecanoic acid (MUA). Extensive tests of the products demonstrated high colloidal density as well as excellent stability, shelf life, and biocompatibility. Specific tests with X-ray diffraction, UV-visible spectrometry, visible microscopy, Fourier transform infrared spectroscopy, dark-field visible-light scattering microscopy, and transmission electron microscopy demonstrated that MUA, being an effective surfactant, not only allows tunable size control of the nanoparticles, but also facilitates functionalization. The nanoparticle sizes were 6.45 ± 1.58, 1.83 ± 1.21, 1.52 ± 0.37 and 1.18 ± 0.26 nm with no MUA and with MUA-to-Au ratios of 1:2, 1:1, and 3:1. The MUA additionally enabled functionalization with l-glycine. We thus demonstrated flexibility in controlling the nanoparticle size over a large range with narrow size distribution.     

基于3，4-乙撑二氧基噻吩环配体的铜/锌配合物的合成、晶体结构及性质

利用3,4-乙撑二氧基噻吩-2,5-二羧酸(H_2L_1)为主配体,2,2′-联吡啶(L_2)、4,4′-联吡啶(L_3)为辅配体,分别与二水合氯化铜、氯化锌通过溶剂热反应得到配合物{[Cu_2(L_1)_2(L_2)(H_2O)_2(DMF)]·3H_2O}n (1)(DMF=N,N-二甲基甲酰胺)和配合物{[Zn(L_1)(L_3)(H_2O)2]·H_2O}n (2)。通过X射线单晶衍射法、红外光谱、元素分析、紫外光谱、荧光光谱、热重分析等测试手段对其结构进行了表征与性质研究。单晶结构分析表明:配合物1是由L_1~(2-)桥联Cu~(2+)形成的二维层状结构,并进一步通过氢键作用形成三维网络结构。配合物2是由L_1~(2-)连接Zn~(2+)形成一维链,并进一步桥联4,4′-联吡啶形成为一维带状结构,通过配位水分子与配体氧原子的氢键作用及带与带之间的π-π堆积形成三维结构。荧光分析和热重分析结果分别表明配合物1和2均有良好的荧光性能和热稳定性。配合物1和2的最大发射波长分别为364和365 nm。     

Fuzzy linear programming models for new product design using QFD with FMEA

Quality function deployment (QFD) is a customer-driven approach in processing new product developments in order to maximize customer satisfaction. Determining the fulfillment levels of design requirements (DRs) and parts characteristics (PCs) is an important decision problem during QFD activity processes for new product development. Unlike the existing literature, which mainly focuses on the determination of DRs, this paper proposes fuzzy linear programming models to determine the fulfillment levels of PCs under the requirement to achieve the determined contribution levels of DRs for customer satisfaction. In addition, considering the design risk, this paper incorporates failure modes and effect analysis (FMEA) into QFD processes, which is treated as the constraint in the models. To cope with the vague nature of product development processes, fuzzy approaches are used for both FMEA and QFD. The illustration of the proposed models is performed with a numerical example to demonstrate the applicability in practice.     

溶致液晶模板电化学沉积束状铂纳米材料

以非离子型三嵌段共聚物EO106PO70EO106 (F127)/正丁醇/氯铂酸水溶液构建的溶致液晶层状相为模板, 电化学沉积制备铂纳米材料. 透射电镜和扫描电镜显示, 产物为具有高长径比的纳米线形成的束状结构, 能量弥散谱与电极电势分析证实产物为铂单质, 而循环伏安测量表明产物的比表面积约为53 m2•g−1. 对影响产物形貌的因素和产物生成的可能机理进行了分析.     

Network structures of polyhedral oligomeric silsesquioxane based nanocomposites: a Monte Carlo study

The network structures of polyhedral oligomeric silsesquioxane based nanocomposites are studied by continuous-space Monte Carlo simulations. The nanoporous network contains intercubic pores and mesopores which can be clearly identified in this work. In terms of degree of cross linking and pore size distribution (PSD), effects of linker length, tether rigidity, and number of reactive tethers are examined. It is found that the extent of cross linking as well as the intercubic pore size of the network increases as linker length increases which are consistent with experimental findings. However, the mesopores appear to shift to a smaller radii regime for networks with longer linkers. Networks with rigid tethers contain lots of free linkers, thus, low cross linking density and narrow PSD are observed. On the other hand, reduction of the reactive tethers shows an insignificant effect on the degree of cross linking of the system. The fact that the intercubic pore size increases as the number of reactive tethers decreases causes the nanobuilding blocks to possess larger free volumes and distribute themselves more evenly throughout the system. As a result, it reduces the possibility of forming large mesopores.     

氧化还原反应相关概念学习困难诊断与教学建议

采用测验、访谈等实证研究方法,对高一新生学习氧化还原反应的困难进行诊断分析,发现学生对化合价认识不足,缺少从微观层面来理解氧化还原反应相关概念。在学习困难分析的基础上设计教学,进行课堂实践研究。