Unsaturated bond existing in tetrafluoroethylene-propylene-vinylidene fluoride terpolymer

Infrared and nuclear magnetic resonance (NMR) spectroscopies have been applied for quantitative comparison on unsaturated bonds in tetrafluoroethylene (TFE)-propylene (P)-vinylidene fluoride (VdF) terpolymers. These spectroscopies have led to consistent results while they are based on completely different principles. It is shown that the absolute concentration can be evaluated from NMR measurements. The behavior of unsaturation has been discussed in terms of after-treatment such as wet and dry treatments. The result obtained here can give the important information to improve the performance of fluoroelastomer based on TFE-P-VdF terpolymers.     

基于相依成分分析-红外光谱法的黄芩炮制过程分析

将相依成分分析(DCA)算法用于模拟混合组分红外光谱(IR)分析及黄芩炮制过程分析与终点确定。研究结果表明,DCA法能从黄芩炮制过程测定的IR信号中提取相依组分(DC)信息,而且这些DC对应的光谱特征信息与对应的黄芩活性组分光谱特征相一致;通过观测DC相对强度变化趋势,确定黄芩炮制过程终点为55 min。该研究为黄芩炮制过程分析与终点确定提供了新途径。     

Curved Ferroelectric Liquid Crystal Matrix Displays Driven by Field-Sequential-Color and Active-Matrix Techniques

This paper describes a curved field-sequential-color matrix display using fast-response ferroelectric liquid crystal. Black matrix and transparent electrode patterns were formed on a thin plastic substrate by a transfer method from a glass substrate. While a composite film of liquid crystal and micro-polymers of walls and fibers was formed between the flexible substrates by printing, laminating and curing processes of a solution of monomers and liquid crystal, the mechanical stability was enhanced by use of multi-functional monomers to form large display panels. The image pixels of the matrix panel were driven by an active matrix scheme using an external switch transistor array at a frequency of 180 Hz for intermittent three-primary-color backlight illumination. The flexible A4-paper-sized color display with 24 × 16 pixels and 60 Hz field frequency was demonstrated by illuminating it with sequential three-primary-color lights from light-emitting diodes of the backlight. Our display system is useful in various information displays because of its freedom of setting and location.     

会聚厄米-双曲余弦高斯光束的光强分布和焦移

 基于厄米-双曲余弦高斯光束通过无光阑限制薄透镜聚焦的解析传输公式，研究了厄米-双曲余弦高斯光束聚焦区域的光强分布，并对光束的焦移进行了分析，讨论了偏心参数对光强主极大位置的影响。结果表明：TEM₁₁模厄米-双曲余弦高斯光束的相对焦移（绝对值）随偏心参数和菲涅尔数的减小而增大，菲涅尔数较大时相对焦移趋于零。TEM₂₂模光束在偏心参数小于0.54时，轴外与轴上光强极大值的比值大于1，此时光强主极大在轴外，偏心参数大于0.54时则相反；在偏心参数等于0.54时比值为1，此时光束有两个主极大，偏心参数愈大光强愈集中于轴上。使用LW法和GH法得到的TEM₂₂模光束的相对焦移（绝对值）随偏心参数和菲涅尔数的变化规律与TEM₁₁模光束一致，但相同参数下使用这两种方法得出的具体结果不同。     

The structure of monolayer SiO2 on Mo(1 1 2): A 2-D [Si-O-Si] network or isolated [SiO4] units?

In this letter, atomically resolved scanning tunneling microscopic (STM) images obtained from monolayer SiO₂/Mo(1 1 2) are presented. The results are consistent with a previously proposed structural model of isolated [SiO₄] units based on vibrational features observed by high-resolution electron energy loss spectroscopy (HREELS) and infrared reflection-absorption spectroscopy (IRAS), and oxygen species identified by ultra-violet photoemission spectroscopy (UPS). These results are inconsistent with a structural model that assumes a two-dimensional (2-D) [Si-O-Si] network. These data illustrate that a metal substrate, although coated with an oxide thin layer, can be directly imaged at the atomic-scale with STM.     

Perforated nanocap array: Facile fabrication process and efficient surface enhanced Raman scattering with fluorescence suppression

Recently, individual reduced-symmetry metal nanostructures and their plasmonic properties have been studied extensively. However, little attention has been paid to the approach to fabricating ordered reduced-symmetry metal nanostructure arrays. In this paper, a novel perforated silver nanocap array with high surface-enhanced Raman scattering (SERS) activity and fluorescence suppression is reported. The array is fabricated by electron beam evaporating Ag onto the perforated barrier layer side of a hard anodization (HA) anodic aluminum oxide (AAO) template. The morphology and optical property of the perforated silver nanocap array are characterized by an atomic force microscope (AFM), a scanning electron microscope (SEM), and absorption spectra. The results of SERS measurements reveal that the perforated silver nanocap array offers high SERS activity and fluorescence suppression compared with an imperforated silver nanocap array.     

微机构可调谐阵列滤光片的设计与模型分析

提出一种新颖的采用薄膜技术在玻璃基底上构造微机可调谐二维窄带滤光片阵列的方法,对器件进行了膜系设计及光谱响应模拟,通过器件的电动力学模型分析,设计出器件的形状与尺寸。     

基于红外检测的H2S传感器中光谱吸收的理论

对于光纤红外的方法检测污染气体的浓度,光谱吸收理论具有非常重要的意义。根据朗伯-比尔(Beer-Lambert)理论,首先从硫化氢(H2S)气体浓度的定量分析以及分子参数的理论进行研究,再通过分析该气体的吸收线得出该气体的吸收系数α(ν)的一般方法。并得到,在气体压强小于0.03个标准大气压(atm,1atm=1.01325×105Pa)时用高斯(Gaussian)线型拟合,大于2atm时用洛伦兹(Lorentzian)线型拟合,它们的相对误差都控制在小于0.1的范围之内。压强在0.03—2atm之间时,吸收线型用福赫特(Voigt)线型拟合比较好,理论上得到很好的结果。     

基于特征基函数的球面共形微带天线阵列分析

采用全波分析法对球面共形微带天线阵列进行了分析.相比体-面积分方程,采用球并矢格林函数的面积分方程法可以大幅减少未知量的数目,进而缓解计算机内存压力.微带天线阵列表面采用曲面三角形剖分,可较精确地模拟球面特性.首先,引入边界电荷以及半Rao-Wilton-Glisson基函数,成功实现了探针馈电,并采用镜像法解决了馈电边处线积分奇异问题.然后,采用特征基函数法降低了阻抗矩阵的阶数,并采取有效措施进一步节省内存和计算时间.最后,分析计算了不同尺寸的球面共形微带天线阵列的输入阻抗及远区场特性.与文献和仿真软件结果进行比较,证明了所提出的处理方法的正确性和有效性.     

Simultaneous determination of nine nucleosides and nucleobases in different Fritillaria species by HPLC‐diode array detector

A sensitive and reliable HPLC‐diode‐array detector method was developed for the first time to simultaneously determine nine nucleosides and nucleobases including uracil, cytidine, guanine, uridine, thymine, inosine, guanosine, thymidine and adenosine in 13 different Fritillaria species. The analysis was performed on a BaseLine C18 column with a gradient of acetonitrile in water at a flow rate of 0.8 mL/min. The diode‐array detector wavelength was set at 260 nm for the UV detection of nucleosides and nucleobases. Satisfactory separation of these compounds was obtained in less than 40 min. The optimized method provided good linear relation (r² >0.9995 for all the investigated analytes), satisfactory precision (RSD <1.51%) and good recovery (from 97.64 to 101.16%). The established method was successfully applied to simultaneous determination of nine nucleosides and nucleobases in 61 batches of samples from 13 Fritillaria species collected from different habitats in China, which could be helpful to control the quality of Fritillaria bulbs.