2-(4-Formylphenyl)phenanthroimidazole as a Colorimetric and Fluorometric Probe for Selective Fluoride Ion Sensing

An easy-to-prepare chemosensor, 2-(4-formylphenyl)phenanthroimidazole 1, synthesized by facile one-step condensation under microwave irradiation, has been indicated to be a colorimetric and fluorometric probe for fluoride anion with good sensitivity and high selectivity. This probe shows obvious red shift and absorbance intensity changes in UV absorption and fluorescence spectra in the presence of fluoride anions. Such color and absorbance intensity changes are attributed to the deprotonation of N-H on the imidazole moiety with fluoride anion.     

一类拟线性次椭圆方程弱解的局部唯一性

In this note,we obtain some a-priori estimates for gradient of weak solutions to a class of subelliptic quasilinear equations constructed by Ho¨rmander’s vector fields,and then prove local uniqueness of weak solutions.A key ingredient is the estimated about kernel on metirc ＂annulus＂.     

Omni-directional mirror for visible light based on one-dimensional photonic crystal

The omni-directional reflection characteristics of one-dimensional photonic crystals composed of Ta 2 O 5 /MgF 2 multi-quantum well (MQW) are studied using the transfer matrix method. An omni-directional reflector consisting of three and four Ta 2 O 5 /MgF 2 MQWs is investigated. Results show that the photonic band gap of the photonic crystal composed of three and four Ta 2 O 5 /MgF 2 MQWs, which are within the wavelength ranges of 402–712 and 412–1,023 nm, respectively, could cover the entire visible region. The relationship among the width of the band gap, its location, reflectivity rate, and incident angle of the incident light is analyzed. The optimal structural parameters of the MQW of the omni-directional reflector in the visible region are also calculated. The calculations provide a guide for the design of omni-directional reflection devices in the visible region.     

一批金元时期古玻璃的EDXRF探针无损分析

利用EDXRF探针无损分析技术,分析了河南禹县阳翟遗址出土的一批金元时期的玻璃样品,以研究这批古玻璃的工艺技术特点.分析显示,所有蓝色玻璃样品的呈色剂均为CuO,而非CoO.从化学组成来看,这批古玻璃的种类较为复杂,主要包括钾钙玻璃、钠钙玻璃和铅钾钙玻璃等.     

高温超导悬浮系统的振动属性研究

本文研究了YBCO高温超导磁悬浮系统在竖直方向上不同的悬浮高度,不同的振动频率扰动下的振动属性．研究表明在一般的小的扰动下,悬浮系统类似于一个弹簧系统,该系统可以恢复到初始的悬浮高度．而当系统受到一个共振频率的扰动时,系统会发生剧烈的振动,会引起能量的损失,悬浮高度的降低．系统的共振频率会随着系统初始悬浮高度的降低而增...     

Tunable chirped microwave photonic filter employing a dispersive Mach-Zehnder structure

A Mach-Zehnder structure with modulation in one arm and dispersive time delay in the other is proposed to implement highly flexible single-bandpass chirped microwave photonic filters based on broadband optical sources. Both the amplitude response and the time delay slope can be fully reconfigured via control of the optical spectra and dispersion. The passband can also be widely tuned without changing the shape. A chirped filter with a bandwidth of ～4?GHz, a delay slope of ～-0.6?ns/GHz, and a tunability up to 40?GHz is demonstrated experimentally.     

Tunable 360° photonic radio frequency phase shifter based on optical quadrature double-sideband modulation and differential detection

We propose a novel structure of a photonic RF phase shifter based on the vector-sum principle. The optical signal with quadrature double-sideband modulation passes through a dual-output Mach-Zehnder interferometer (MZI), and the two outputs are differentially detected. Two phase-quadrature RF terms are generated, and their amplitudes can be controlled in a triangularly complementary way by changing the phase of the MZI. A full tuning range of 0°-360° at 14?GHz is demonstrated experimentally accompanied by nearly constant RF amplitude. The validity of using our scheme in all-optical RF phase modulation is also verified.     

Cotton fabric coated with nano TiO2-acrylate copolymer for photocatalytic self-cleaning by in-situ suspension polymerization

Two kinds of nano TiO₂-polyacrylate hybrid dispersions, TBM-w and TBM-e were synthesized by in-situ suspension polymerization and solution polymerization respectively, in order to fix the nano TiO₂ on fabrics. The photocatalytic self-cleaning fabrics have received much attention in recent years for its water-saving and environment-protection advantages. However, the fixation of the photocatalyst on fabrics is still a key problem that inhibits industrialization of these eco-friendly fabrics. The cotton fabric was treated by the two hybrid dispersions. The photocatalytic self-cleaning property was characterized. Infrared spectroscopy, burning loss test and thermogravimetry showed that some copolymer chains entangled with the nano TiO₂. Transmission electron microscope illustrated that there was a polymeric layer on the surface of nano TiO₂. The average diameter of TBM-w was smaller than that of TBM-e based on size analysis. The photocatalytic decoloration of the grape syrup indicated that the fabric with TiO₂-polymer hybrid had excellent self-cleaning property.     

Development of long-life-cycle tablet ceramic adsorbent for geosmin removal from water solution

In this study, the tablet ceramic adsorbent (TCA), a silica/iron(III) oxide composite material, has been developed for geosmin (GSM) removal from the water solution. The physicochemical characteristics of TCA were examined with XRD, SEM, EDX and BET analyses. The sorption characteristics of GSM on TCA were investigated in a batch system. Attempts have been made to understand the adsorption kinetics, the effect of initial GSM concentration, solution pH, and reaction time.The batch experiments equilibrium data were well fitted to the Lagergren kinetic equation, which indicate the first-order nature adsorption. Over 82% of the GSM was removed by the TCA within 600 min at an initial concentration of 200 ng/L with 20 g/L of TCA dose. The batch and regeneration study indicated that the TCA is a cost-effective GSM adsorbent with sufficient mechanical strength to retain its physical integrity after long-time adsorption, and high regeneration performance for long-life-cycle application. Almost no second contamination (toxic sludge or leached iron) was observed after adsorption, and the gas resultant of thermal regeneration is harmless to atmospheric environment.