三维镍(Ⅱ)-镧(Ⅲ)混金属配位聚合物的合成、晶体结构及其荧光性质

以1,2,3-三氮唑基杂环多羧酸H_3ctia(H_3ctia=5-(4-carboxyl-1H-1,2,3-triazol-1-yl) isophthalic acid)为配体合成了一系列三维镍(Ⅱ)-镧(Ⅲ)混金属配位聚合物[Ln_2Ni(tia)_4(H_2O)_4]_n(Ln=La (1)、Ce (2)、Pr (3)、Nd (4)、Sm (5)、Eu (6)、Gd (7)、Tb (8)、Dy (9))和{[Yb_2Ni(tia)_4(H_2O)_2]·2H_2O}_n(10)(tia=5-(1H-1,2,3-triazol-1-yl)isophthalate)。X射线单晶衍射测试表明,配合物1~10皆具有三维网格结构,其中配合物1~9同构,而配合物10的组成与1~9一样,但晶体学结构则完全不同。在可见光区域,化合物5、6、8和9分别出现了Sm、Eu、Tb和Dy的特征发射峰,其中配合物6、8和9的荧光寿命分别为234、598和2.96μs;在近红外区域,配合物4、9和10分别出现了Nd、Dy和Yb的特征发射峰,对应的荧光寿命分别为4.25、3.42和5.66μs。     

测定晶体结构的系统试差法的研究(Ⅲ)──SYSTEM 90程序系统和应用

介绍了最近研究的系统试差法的基本公式和它的程序系统SYSTEM90的构成．应用该程序系统对收集到的5个难解结构进行了成功的测定．实验结果显示了SYSTEM90程序系统的威力．最后在分析的基础上，提出了系统试差法程序系统不同于其它直接法的四个特点．     

在含乙醇的硅铝凝胶中合成ZSM-5沸石

用含乙醇的硅铝凝胶水热晶化合成ZSM-5沸石.实验表明,乙醇能够促进ZSM-5沸石晶体的成核和生长,具有明显的模板剂作用.向含乙醇的凝胶中加入晶种可以进一步缩短晶化诱导期和晶化时间,并减小分子筛的晶粒度.晶种的粒度与分子筛产物的晶粒度有一定对应关系.采用搅拌晶化也能明显地减小ZSM-5沸石的晶粒度,同时影响晶体形貌.通过优化晶化条件和凝胶组成,成功合成出硅铝比在30～240范围内、结晶度较高的ZSM-5沸石分子筛,所得沸石孔道畅通,热稳定性、水热稳定性高,且具有较强酸性,具有良好的应用前景.     

以HPD-750大孔树脂为载体材料固定化果胶酶

HPD-750树脂是中极性大孔吸附树脂,生物相容性好,机械性能稳定,具有较大的比表面积,可用于固定化酶载体材料。本文以HPD-750大孔树脂为载体固定化果胶酶,研究各因素对固定化酶的影响,并采用正交试验对固定化条件进行优化。结果表明,当pH为4.0、固定化温度为45℃、固定化时间为4h、加酶量为0.16g/mL时,固定化酶活力可达5146U/mg。以HPD-750大孔树脂为载体材料制备的固定化酶相较于游离酶具有更好的酸碱稳定性和热稳定性。在循环使用10次后,酶活力依然保留80%以上;4℃储藏25d之后,其酶活力仍保留60%以上。与D311大孔树脂、聚丙烯酰胺和海藻酸钠微球制备的固定化酶相比,HPD-750大孔树脂固定化酶的活性、操作稳定性、机械稳定性和储存稳定性都较好。该结果说明,HPD-750大孔树脂可作为固定化酶较好的载体材料。     

Robust CCD photoelectric autocollimator for outdoor use

A robust charge-coupled device(CCD) photoelectric autocollimator for outdoor use is designed and demon-strated. The influence of outdoor conditions on the signal-to-noise ratio(SNR) and imaging quality of the measuring system is experimentally analyzed. The pulse width modulation technology is applied to the automatic feedback control of the actively regulated illuminating light source of the measuring system to maximize SNR while avoiding image saturation. A Fourier phase shift method for subpixel estimation is adopted to achieve high-accuracy measurement in the presence of noises. Experimental results indicate that the technologies proposed here largely improve the measuring stability,dynamic range,and accuracy of the CCD photoelectric autocollimator used outdoors.     

引信安全系统过程识别理论及其可靠性

将马尔可夫（Ｍａｒｋｏｖ）过程理论应用于引信安全系统的状态转移过程,通过状态转移过程分析和状态转移概率的计算,建立起引信安全系统过程识别理论,并得到计算该系统可靠性的方法。     

Thermoelectric-transport in metal/graphene/metal hetero-structure

We investigate the thermoelectric-transport properties of metal/graphene/metal hetero-structure. We use a single band tight-binding model to present the two-dimensional electronic band structure of graphene. Using the Landauer--Butticker formula and taking the coupling between graphene and the two electrodes into account, we can calculate the thermoelectric potential and current versus temperature. It is found that in spite of metal electrodes, the carrier type of graphene determines the electron motion direction driven by the difference in temperature between the two electrodes, while for n type graphene, the electrons move along the thermal gradient, and for p type graphene, the electrons move against the thermal gradient.     

Measuring thermoelectric property of nano-heterostructure

A method of measuring the thermoelectric power of nano-heterostructures based on four-probe scanning tunneling microscopy is presented. The process is composed of the it in-situ fabrication of a tungsten-indium tip, the precise control of the tip-sample contact and the identification of thermoelectric potential. When the temperature of the substrate is elevated, while that of the tip is kept at room temperature, a thermoelectric potential occurs and can be detected by a current-voltage measurement. As an example of its application, the method is demonstrated to be effective to measure the thermoelectric power in several systems. A Seebeck coefficient of tens of μV/K is obtained in graphene epitaxially grown on Ru (0001) substrate and the thermoelectric potential polarity of this system is found to be the reverse of that of bare Ru (0001) substrate.     

A leap-frog discontinuous Galerkin time-domain method of analyzing electromagnetic scattering problems

Several major challenges need to be faced for efficient transient multiscale electromagnetic simulations, such as flexible and robust geometric modeling schemes, efficient and stable time-stepping algorithms, etc. Fortunately, because of the versatile choices of spatial discretization and temporal integration, a discontinuous Galerkin time-domain(DGTD) method can be a very promising method of solving transient multiscale electromagnetic problems. In this paper, we present the application of a leap-frog DGTD method to the analyzing of the multiscale electromagnetic scattering problems. The uniaxial perfect matching layer(UPML) truncation of the computational domain is discussed and formulated in the leap-frog DGTD context. Numerical validations are performed in the challenging test cases demonstrating the accuracy and effectiveness of the method in solving transient multiscale electromagnetic problems compared with those of other numerical methods.     

检测硫化氢分子的荧光探针

硫化氢（H₂S）是继一氧化碳和一氧化氮之后,第三种可在生命体内发挥生理作用的内源性气体信号分子。该气体分子在心血管和神经系统中担负着重要的生理病理调节作用。因此,选择性识别和高灵敏检测生物体内的H₂S具有十分重要的生物医学意义。在生物检测技术手段中,荧光探针法具有选择性好、灵敏度高、对生物样品损伤小以及可实现实时原位检测等独特的优势,故应用荧光探针法检测细胞内H₂S浓度的变化是近年来研究热点之一。本文依据荧光探针与H₂S之间的化学反应类型,将近三年来所研发的H₂S荧光探针按照其母体荧光团进行分类和总结,综述了H₂S荧光探针的研究进展,概述了相关荧光探针的设计理念、检测机理及生物应用,探讨了探针的结构和性能之间的关系,最后展望了H₂S荧光探针的发展趋势和应用前景。