CSRe Schottky 质量谱仪研究

HIRFL-CSR 联合Schottky信号诊断的方法为高精度测量离子质量提供了一个新的途径，本论文研究了CSRe Schottky 质量谱仪的原理,电子冷却模式下进行质量测量时的磁铁设置，各种系统误差以及能达到的精度估计。首先研究了CSRe的线性lattice中动量压缩因子对动量色散的依赖，以及动量压缩因子的高阶项的存在会对常用的线性质量刻度造成多大的系统误差。讨论了利用六级铁的适当设置减小这种系统误差的方法，给出利用MAD程序的模拟的CSRe六级铁的适当设置数值以及动量压缩因子对动量分散的依赖曲线。接着详细讨论了其他的几种主要的系统误差以及消除方法，给出了一种新的准确度更高的非线性的质量刻度方法。最后研究了电子冷却模式下CSRe Schottky质量谱仪精度的决定因素，调研了在CSRe上进行对190Ir和188Os可行性以及估计了在现有条件下，能够达到的精度,探讨了进一步提高质量刻度的精度和准确度的实现途径

浅论实现基于MapX的灌溉信息系统的关键技术

现代化的灌溉用水管理是实现农业高效用水的重要措施之一,它可实现灌溉水资源的合理配置和灌溉系统的优化调度,达到节水增产目的,使有限的水资源获得最大的效益。采用手工方式进行灌溉用水管理,难以及时提供水资源利用最优化方案,因此急需研制出具有网络通信功能的可视化操作界面的灌溉信息管理系统,为灌区水资源评价和利用、规划等工作奠定良好的数据基础。GIS不仅具有强大的空间数据管理功能,还具有丰富的多元地学数据分析处理能力和直观的图形显示效果,因此利用GIS进行灌区的管理与建设将会有效提高灌区的工作效率和经济效益。笔者在实践调研的基础上,根据灌溉信息管理系统的功能规划及结构设计,利用MapX组件工具开发了陕西省冯家山灌区灌溉信息系统,对提高灌溉用水的管理效率进行了实例尝试,并着重对下列关键技术的运用进行了实践与思考:(1)阐述了利用可视化编程工具结合数据库管理技术、地理信息系统组件技术、网络通信技术等进行系统开发的过程;(2)着重介绍了基于MapX组件的空间数据库的建立与关联技术、灌溉管理信息的网络通信实现技术;(3)最后对在灌溉管理工作中运用GIS技术进行科学管理等相关问题进行了有益的探讨。

Efficient One-Pot Synthesis of Highly Substituted Thiophene Library from 1,3-Dicarbonyl Compounds

A faccile and efficient one-pot synthesis of highly substituted thiophenes has been developed and employed for the preparation of a small focused library. Treatment of 1,3-dicarbonyl compounds 1 with CS2 in the presence of K2CO3 in DMF at room temperature, followed by stepwise addition of alkyl bromides 2 and methylene active bromides 3, provided via intramolecular cyclization 2,3,4,5-tetrasubstituted thiophenes 4 in yields of 77-94%. This protocol, combining construction and modification of the thiophene ring, increases the structural diversity of final products from readily available materials. A mechanism for the one-pot synthesis of thiophenes of type 4 has been proposed. A small focused library of thiophenes is prepared using the sequential addition of reagents to achieve unique substitution in the 2 and 5 position of the thiophene ring

Manipulating charge-transfer character with electron-withdrawing main-group moieties for the color tuning of iridium electrophosphors

A new and synthetically versatile strategy has been developed for the phosphorescence color tuning of cyclometalated iridium phosphors by simple tailoring of the phenyl ring of ppy (Hppy=2-phenylpyridine) with various main-group moieties in [Ir(ppy-X)(2)(acac)] (X=B(Mes)(2), SiPh3, GePh3, NPh2, POPh2, OPh, SPh, SO2Ph). This can be achieved by shifting the charge-transfer character from the pyridyl groups in some traditional iridium ppy-type complexes to the electron-withdrawing main-group moieties and these assignments were supported by theoretical calculations.

Nanostructured bulk novel hard material with "rounded" grains obtained by nanocrystalline "rounded" (W0.5Al0.5)C powders

A novel nano-scaled bulk hard material (W0.5Al0.5)C-Co with "rounded" grains was prepared by nanocrystalline "rounded" (W0.5Al0.5)C powders with "rounded" particle shape in this study. The nano-scaled "rounded" particles do not contain sharp edges, which form local tensile stress concentrations on loading of the composite, thus leading to improved toughness and reduced sensitivity to crack. Nanocrystalline (W0.5Al0.5)C powders with "rounded" particle shape were used as starting materials. X-ray diffraction, scanning electron microscopy, and transmission electron microscopy were used to characterize the samples.

Preparation and evaluation of a proton exchange membrane based on oxidation and water stable sulfonated polyimides

A series of novel oxidation and water stable sulfonated polyimides (SPIs) were synthesized from 4,4'-binaphthyl-1,1',8,8'-tetracarboxylic dianhydride (BTDA), and wholly aromatic diamine 2,2'-bis(3-sulfobenzoyl) benzidine (2,2'-BSBB) for proton exchange membrane fuel cells. These polyimides could be cast into flexible and tough membranes from m-cresol solutions. The copolymer membranes exhibited excellent oxidative stability and mechanical properties due to their fully aromatic structure extending through the backbone and pendant groups. Moreover, all BTDA-based SPI membranes exhibited much better water stability than those based on the conventional 1,4,5,8-naphthalenecarboxylic dianhydride. The improved water stability of BTDA-based polyimides was attributed to its unique binaphthalimide structure. The SPI membranes with ion exchange capacity (IEC) of 1.36-1.90 mequiv g(-1) had proton conductivity in the range of 0.41 x 10(-1) to 1. 12 x 10(-1) S cm(-1) at 20 degrees C. The membrane with IEC value of 1.90 mequiv g(-1) displayed reasonably higher proton conductivity than Nafion((R)) 117 (0.9 x 10(-1) S cm(-1)) under the same test condition and the high conductivity of 0.184 S cm(-1) was obtained at 80 degrees C. Microscopic analyses revealed that well-dispersed hydrophilic domains contribute to better proton conducting properties. These results showed that the synthesized materials might have the potential to be applied as the proton exchange membranes for PEMFCs.

Fabrication of self-assembled palladium nanosheets using layered organic/inorganic hybrid as the template

In this paper, a simple route to the fabrication of palladium nanosheets is described. The interaction of palladium chloride (PdCl2) and n-octylamine salt resulted in the formation of a quasi-perovskite-type composite with a layered structure on a molecular scale. This composite can be employed as a template for preparing ultrathin Pd nanosheets when a {PdCl4}(2-) network is reduced in situ by hydrogen in toluene. The x-ray diffraction results indicate that the resulting Pd nanosheets are highly ordered, and they are confined inside the organic matrix as evidenced by high resolution transmission electron microscopy. These Pd nanosheets can be reorganized into layered structures in non-polarized organic solvent when the ordered structure is destroyed. This method of preparing Pd nanosheets is expected to be applicable to other layered organic/inorganic perovskite systems for obtaining the corresponding metal nanosheets.

Hydrothermal synthesis and crystal structure of a novel compound: [Ni(phen)(3)](2)[(SiMo10V2O40)-O-IV((VO)-O-IV)2]center dot 2H(2)O

A novel compound [Ni(phen)(3)](2)[(SiMo10V1/2O40)-O-V((VO)-O-IV)(2)] . 2H(2)O has been hydrothermally synthesized and structurally characterized by single-crystal X-ray diffraction. The compound crystallizes in the triclinic, system, space group P-1, a = 12.378(4) Angstrom, b = 14.148(5) Angstrom, c = 14.316(2) Angstrom, alpha = 105.91(2)degrees, beta = 95.31(2)degrees, gamma = 96.89(3)degrees, V = 2373.0(12) Angstrom(3), Z = 1, (lambdaMo(Kalpha)) = 0.71073 Angstrom, R1 (wR2) = 0.0869(0.2174). Data were collected on a Siemens P4 four-circle diffractometer at 293 K in the range of 1.51 < theta < 22.50degrees using the omega-scan technique. Empirical absorption correction (psi scan) was applied. The structure was solved by the direct method and refined by the Full-matrix least-squares on F-2 using the SHELXL-97 software. X-ray crystallographic study showed that the title compound contained a bi-capped alpha-Kegin-type [(SiMo10V2O40)-O-IV((VO)-O-IV)(2)](4-) polyoxoanion.

The effects of physical ageing on crazing of polyphenylquinoxaline films

The effects of physical ageing on the crazing of polyphenylquinoxaline (PPQ-E) films were studied. The DSC endothermic peak at the glass transition region of the samples was interpreted in terms of the cohesional entanglement theory. The free volume cavity size and free volume intensity of the samples were characterized by positron annihilation life spectroscopy. The difference in free volume cavity size and free volume intensity between two samples reflect the strength and density of cohensional entanglement point. The critical strain for craze initiation and craze stability depended on physical ageing of the samples. The relationships between physical ageing and crazing were interpreted initially.

Study on the synthesis of mixed oxide La2CuO4 and the effect on the catalytic activity to catalytic removal of NO

The mixed oxide La2CuO4 was synthesized by four different methods and characterized with XRD, BET, TEM and low angle XRD. The effect of the synthetic method on the crystal structure, crystal size, surface area and catalytic activity to NO - CO reaction were studied. The results showed that the samples derived from different methods exhibited different activity to NO-CO reaction, the reason may be that the concentration and type of oxygen defect were different when the synthetic methods were different.