SPECTRAL CHARACTERISTICS OF FREE AND LINKED PYRENE-TYPE CHROMOPHORES IN SOLUTION,POLYMER MATRICES,AND INTERPENETRATING NETWORKS

Monomers, 1-pyrenylmethyl methacrylate (PyMMA), 1-pyrenylbutyl methacrylate (PyBMA), 4-(1-pyrenyl)methoxymethyl styrene (PyMMS) and allyl-(1-pyrenylmehtyl) ether (PyMAE), with pyrene as chromophore, were prepared. Their spectral properties (absorption, emission and emission decay) in solution, and doped or bonded in polymer matrices and complex polymer systems as interpenetrating polymer networks (IPN), were investigated. Spectral properties of pyrene-containing monomers doped in polystyrene (PS), polymethylmethacrylate (PMMA), polyvinylchloride (PVC), polyethylene (PE) and grafted on PE as well as copolymerized in buthylmethacrylate-co-styrene copolymer (BMA-co-S) have been compared. Absorption and emission spectra of pyrene type probes in solution and in IPN matrices exhibit typical absorption of the pyrene moiety. For IPN with grafted probes on PE, the absorption is slightly shifted to red wavelength. For monomers, PyMMA, PyBMA and PyMAE grafted to PE, the shape of the emission spectrum depends on the wavelength of excitation. The ratio of intensity of the vibrational band, I₁/I₃, (I₁ peak at 377 nm and I₃ peak at 388 nm) has been a quite useful indicator of polarity of IPN. The relative quantum yields of fluorescence in IPN matrices are lower in comparison to polymer matrices of PE, PS, PMMA for all probes under study. The fluorescence life-times for bound and free probes have been in the range 100–200 ns, which is substiantialy shorter than for the parent pyrene chromophore under the same or similar condition. Grafted probes on PE alone, or as a part of IPN, exhibit substantially shorter life-time around 10 ns and decay is rather complex.     

Electron Spin Resonance Study on Grafting of Tetrafluoroethylene onto Polyethylene

An ESR study has been made on the course of grafting of tetrafluoroethylene onto polyethylene. Alkyl and allyl radicals trapped in the polymers were measured under various grafting conditions. It was observed that alkyl radicals decay very rapidly when monomers are in contact with the irradiated polymer, while allyl radicals decay very slowly even in the presence of monomers as in the decay of radicals in irradiated polymers without monomers. The effect of pre-irradiation temperature on grafting was also studied, and the rate of grafting was found to be much faster for lower pre-irradiation temperatures. From these experimental results it was concluded that alkyl radicals play an important Tole in the initiation reaction of grafting.     

Helical Biphenyl Bisazo Polyurethane: Preparation,Characterization and Analysis of Polymeric Thermo-Optic Switch

The bisazo chromophore molecule (CAAPM) and helical biphenyl bisazo polyurethane (HBBPU) were synthesized. The structures of CAAPM and HBBPU were characterized by FT-IR and UV-vis spectroscopic techniques. The measurements of refractive index and thermo-optic coefficient (dn/dT) of HBBPU were demonstrated at different wavelengths and different temperatures by the ATR technique. By using CCD digital imaging devices, transmission loss of the internal waveguide was measured. The refractive index dispersions and Sellmeyer coefficients of HBBPU were obtained by the Sellmeyer equation. A Y-branched switch based on the thermo-optic effect was proposed and the performance of the switch was simulated. With a branching angle of 0.143° and the FD-BPM method, the result showed that the power consumption of the thermo-optic switch could be only 3.6 mW, and the response time of the switch could reach about 8 ms. This is a significant improvement in reducing power consumption compared with the normal Y-branched polymer thermo-optic switch.     

基于单片机和光电开关的通用计数器设计

At presrent, the photoelectric switch is more and more widely used in the industrial automation equipment.It can be finished counting industrial products by using the characteristic of the photoelectric switch which can detect the objects without touching them. This design uses the modular design method,including power-supply module, The photoelectric conversion module, optocoupler isolation circuit module, power off protection module, matrix keyboard module, counting module and The display module. It mainly uses 51 single-chip microcomputer to control the system,uses the keilC51 software to design program,uses the Proteus software to complete the simulation. Through the experiment, it proves the design is feasible.     

Trace formulas for additive and non-additive perturbations

Trace formulas for pairs of self-adjoint, maximal dissipative and accumulative as well as other types of resolvent comparable operators are obtained. In particular, the existence of a complex-valued spectral shift function for a pair {H^′,H}$\{H^{\prime },H\}$ of maximal accumulative operators has been proved. We investigate also the existence of a real-valued spectral shift function. Moreover, we treat in detail the case of additive trace class perturbations. Assuming that H   and H^′=H+V$H^{\prime }=H+V$ are maximal accumulative and V is trace class, we prove the existence of a summable   complex-valued spectral shift function. We also obtain trace formulas for pairs {H,H^?}$\{H,H^{?}\}$assuming only that H and  H^?$H^{?}$are resolvent comparable. In this case the determinant of the characteristic function of H is involved in trace formulas.     

GPCR A2A AR腺苷受体蛋白的激动剂结合及其诱导的蛋白活性开关构象变化

运用分子动力学模拟,研究了腺苷酸（激动剂）与A2AAR腺苷受体蛋白的相互作用和配体结合诱导的蛋白动力学变化．识别了与腺苷酸结合力强于0．5kcal／mol的关键基团：A63^2．61,I66^2．64,V84^3.32,L85^3.33,T88^3.36,F168^5.29,M177^5.38,L249^6.51,H250^6.52和N253^6.55,观察到腺苷酸没有与L167^5.28相互作用,这一结果支持了L167^5.28是抑制剂特异性结合位点,不与激动剂结合．未结合配体（激动剂或抑制剂）的单体A2AAR和腺苷酸结合后的A2AAR在构象上有三个不同功能性开关．腺苷酸结合可以诱导A2AAR腺苷受体蛋白的构象调整,使得三个功能性开关器件的构象与单体A2AAR不同．     

(CH3)2和(NH2)2基团修饰的齐聚苯乙炔分子电子输运性质研究

采用密度泛函理论和非平衡格林函数相结合的方法研究了S原子作为单、双端基的(CH₃)₂-OPE (齐聚苯乙炔)和(NH₂)₂-OPE分子在金电极间的电子输运性质. 通过第一性原理优化计算获得分子部分稳定结构, 再置于Au电极之间构成两极系统, 然后再优化整个两极系统获得稳定结构. 另外, 通过非平衡格林函数方法计算了两极系统的电子输运性质. 计算结果表明, 不同的修饰基团和桥接方式可以导致两极系统的开关效应、负微分电阻行为和整流行为等不同的电子输运性质. 通过计算不同偏压下的分子体系投影轨道电子分布、透射谱、态密度, 对这些新异的电输运性质出现的机理进行了解释.     

Spectral editing in solid-state MAS NMR of quadrupolar nuclei using selective satellite inversion

A sensitivity enhancement method based on selective adiabatic inversion of a satellite transition has been employed in a (pi/2)CT-(pi)ST1-(pi/2)CT spectral editing sequence to both enhance and resolve multisite NMR spectra of quadrupolar nuclei. In addition to a total enhancement of 2.5 times for spin 3/2 nuclei, enhancements up to 2.0 times is reported for the edited sites in a mixture of rubidium salts.     

Localization microscopy (SPDM) facilitates high precision control of lithographically produced nanostructures

Nanoscale resolution in material sciences is usually restricted to scanning electron beam microscopes. Here we present a procedure that allows single molecule resolution of the sample surface with visible light. Highlighting the performance we used electron beam lithography to generate highly regular nanostructures consisting of interconnected cubes. The samples were labeled with Alexa 647 dyes. The spatial organization of the dyes on nanostructured surfaces was localized with single molecule resolution using localization microscopy. This succeeded also in an absolute spatial calibration of the localization method applied (spectral precision distance microscopy/SPDM). The findings will contribute to the field of product control for industrial applications and long-term fluorescence imaging.