基于正交复小波变换和小波去噪的改进系统De-OCWDM

用近似线性相位正交复小波变换(ALOCWT)取代了正交频分复用(OFDM)系统中的离散傅立叶变换(DFT),形成了正交复小波波分复用(OCWDM)系统.ALOCWT具有时频特性、正交特性、重构特性等特性,能够很好地取代DFT,同时ALOCWT能够保留复信号的相位信息,使得信号重构精度更高,从而提高了信号传输的准确性和系...     

Bipolar tap photonic microwave notch filter using electroabsorption modulator-integrated distributed feedback laser diodes in a parallel configuration

We propose a bipolar tap photonic microwave notch filter scheme, which can be used to realize a fully integrated, semiconductor-based notch filter. The scheme is based on two electroabsorption modulator (EAM)-integrated distributed feedback laser diodes in a parallel configuration. We show that two filter taps with opposite polarities can be readily obtained by using the negative and positive slopes of the U-shaped electro-optic transfer functions of the EAMs under special design and operating conditions. An experiment was carried out to verify the working principle of the proposed scheme. Notch frequency tuning was also demonstrated by varying the laser wavelength spacing; the spacing was varied by changing the temperature. A frequency tuning range of ~1.8 GHz with a notch depth of ~40 dB was achieved.     

Nanometer resolution stress measurement of the Si gate using illumination-collection-type scanning near-field Raman spectroscopy with a completely metal-inside-coated pyramidal probe

We have proposed an illumination-collection-type scanning near-field Raman spectroscopy (SNRS) with a completely gold metal-inside-coated (MIC) pyramidal probe without an optical aperture in order to detect the Raman spectra of fine Si devices for local stress measurements. The gold MIC pyramidal probe has been studied to act as a plasmon resonance near-field optical probe with high power using a finite differential time domain (FDTD) simulation and the prototyped SNRS. In the simulation, the propagated optical power can be made available for SNRS. In the experiments, it is clear that the prototyped SNRS enhanced the Si Raman peak signal by plasmon resonance and could measure the Si Raman peak shift by line scanning the Si gate region and the Si active layer. Furthermore, compressive and tensile stresses localized around the Si gate were demonstrated by the Si Raman peak shift with a resolution of about 10 nm. It is clarified that the proposed SNRS has the possibility of detecting the Raman spectra of a local area.     

Maleimide photolithography for single-molecule protein-protein interaction analysis in micropatterns

Spatial organization of proteins into microscopic structures has important applications in fundamental and applied research. Preserving the function of proteins in such microstructures requires generic methods for site-specific capturing through affinity handles. Here, we present a versatile bottom-up surface micropatterning approach based on surface functionalization with maleimides, which selectively react with organic thiols. Upon UV irradiation through a photomask, the functionality of illuminated maleimide groups was efficiently destroyed. Remaining maleimides in nonilluminated regions were further reacted with different thiol-functionalized groups for site-specific protein immobilization under physiological conditions. Highly selective immobilization of His-tagged proteins into tris(nitrilotriacetic acid) functionalized microstructures with very high contrast was possible even by direct capturing of proteins from crude cell lysates. Moreover, we employed phosphopantetheinyl transfer from surface-immobilized coenzyme A to ybbR-tagged proteins in order to implement site-specific, covalent protein immobilization into microstructures. The functional integrity of the immobilized protein was confirmed by monitoring protein-protein interactions in real time. Moreover, we demonstrate quantitative single-molecule analysis of protein-protein interactions with proteins selectively captured into these high-contrast micropatterns.     

Energy transfer and luminescence properties of Eu-doped NaTb(WO4)2 phosphor prepared by a facile hydrothermal method

NaTb_(1−x)Eu_x(WO₄)₂ (x = 0-100%) phosphors have been synthesized via a mild hydrothermal process directly without further sintering treatment. X-ray diffraction (XRD), scanning electron microscope (SEM), photoluminescence excitation and emission spectra and decay curve were used to characterize the samples. Moreover, the luminescence colors of NaTb_(1−x)Eu_x(WO₄)₂ (NTbW:Eu) samples can be tuned from green, green-yellow, and yellow to red by simply adjusting the relative Eu³⁺-doping concentrations under a single wavelength excitation, which might find potential applications in the light displays systems.     

Rapid preparation of CuInS2 microparticles via a solution-chemical synthesis route and its characterization

CuInS₂ microparticles were synthesized successfully by a facile solution-chemical method in a mixed solvent of triethylenetetramine–ethylene glycol (1:1, v/v) under the open-air condition using copper chloride, indium chloride and sulfur as starting materials. The factors including the temperature and reaction time which might affect the purity of the product during the synthesis were discussed. Phase constituents, morphology, structure and optical properties of the as-prepared CuInS₂ powders were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), Energy Dispersive Spectrometer (EDS), and ultraviolet–visible (UV–vis) spectrophotometry. It's found that the products were significantly affected by the temperature and reaction time. A possible formation mechanism was put forward and briefly discussed.     

Measurement and modeling solubility of bioactive coumarin and its derivatives in supercritical carbon dioxide

To design a supercritical fluid extraction process for the separation of bioactive substances from natural products, a quantitative knowledge of phase equilibria between target biosolutes and solvent is necessary. How-ever, mostly no such information is available in literature to date. Thus in the present study, illustratively the solubility of bioactive coumarin and its various derivatives (i.e., hydroxy-, methyl-, and methoxy-derivatives) in supercritical CO₂ were measured at 308.15–328.15 K and 10–30 MPa. Also, the pure physical properties such as normal boiling point, critical constants, acentric factor, molar volume and standard vapor pressure for coumarin and its derivatives were estimated. By these estimated information, the measured solubilities were quantitatively correlated by an approximate lattice equation of state proposed recently by the present authors.     

浅析有机粘结剂对等静压喷雾粉料的影响

主要从等静压喷雾粉料的性质和成型性能要求等几个方面分析有机粘结剂对等静压喷雾造粒粉料的影响 ,为完善国产化等静压粉料添加剂提供参考。     

4－（1－哌啶基）哌啶的合成

以苄胺和丙烯酸甲酯为原料，经加成、迪克曼缩合、脱羧制得１－苄基－４－哌啶酮。后者与哌啶通过脱水缩合、氧化还原、还原脱苄得到４－（１－哌啶基）哌啶。     

不对称Reformatsky反应的研究进展

综述了近年来不对称Reformatsky反应在有机合成中的应用。