S-Alkylation en série hétérocyclique par catalyse par transfert de phase: thioalkyl-2-thiazoles,thioalkyl-2-Δ-4-thiazolines et thioalkyl-2-benzothiazoles

S-Alkylation in heterocyclic serie by phase transfer catalysis: 2-alkylthiothiazoles, 2-alkylthio-Δ-4-thiazolines and 2-alkylthiobenzothiazoles Some Δ-4-thiazoline-, thiazolidine-, and benzothiazoline-2-thiones have been S-alkylated by phase transfer catalysis; yields averaged 80 to 90%. With halogenated heterocyclic compounds of poor reactivity, the main reaction consisted in a dequaternization of the catalyst by the thiones acting as nucleophiles.     

电场调谐InAs单量子点的发光光谱

采用稳态和时间分辨发光光谱,研究了生长在p-i-n二极管结构内的InAs单量子点发光光谱的电场调谐特性.随着电场强度的增加,观察到量子点中激子发光的Stark 效应.通过选择不同波长的激光线激发量子点样品,发现随着电场强度的增加导致量子点发光强度的减弱,这是由于量子点俘获载流子概率的减小所致,而激子寿命的增加源于电场导致激子的Stark效应. 关键词： InAs单量子点 Stark效应 电子-空穴分离     

三效吸收式制冷循环系统性能分析

对12个通用的三效循环系统以及这12个通用循环系统组成的76种可能的密闭循环系统进行了评测。根据通用三效循环系统的压力和溶解度要求,对通用三效循环系统进行了分析,并充分考虑各部件设计中的问题和COPs数值,以及处于高腐蚀环境中部件的数目。通过分析,确定了四个性价比较优的系统:Alkitrate Topping循环系统,Pressure Staged Envelope循环系统,High Overlap循环系统和Dual Loop循环系统。     

Structure of Reconstructed Cu(100) Surface Induced by Dissociative Adsorption of Gaseous Oxygen

用低能电子衍射(LEED)和扫描隧道显微镜技术研究了氧气在Cu(100)表面化学吸附所形成的表面重构结构．在低覆盖度下,实验上观察到了两个有序重构的混合相,分别为c(2×2)O重构和(√2×2√2)R45°-O重构．在氧原子的覆盖度逐渐增加的过程中,c(2×2)O重构区域的面积逐渐减小．在初始氧化阶段,实验上观察到了呈条状的“锯齿”形的重构结构,这些锯齿形的结构是由相邻的局域化的c(2×2)区域的边界区域(Cu)构成的．STM实验发现,相对于其他重构区域,这些锯齿形的重构区域与有机分子之间存在更加强烈的相互作用．通过分析在不同退火温度下样品LEED衍射点的变化,研究了重构结构的热稳定性,发现三种结构的热稳定性顺序是：锯齿结构>c(2×2)O重构>(√2×2√2)R45°-O重构．     

在有限空间内生成的晶格高度取向的ZnO纳米颗粒

应用固态反应的方法,在260和300 oC空气中分别热分解层状锌油酸固体得到氧化锌纳米颗粒/团簇．高分辨透射电子显微镜和选区电子衍射表明,这种团簇是带有各种缺陷的单晶．光致发光激发光谱表明这两个样品在272和366 nm有两个频段．前者可能是由于不到200个氧化锌分子组成的团簇从价带到导带的电子转移引起的．     

Mobile Rayleigh Doppler wind lidar based on double-edge technique

<正>We describe a mobile molecular Doppler wind lidar(DWL) based on double-edge technique for wind measurement of altitudes ranging from 10 to 40 km.A triple Fabry-Perot etalon is employed as a frequency discriminator to determine the Doppler shift proportional to the wind velocity.The lidar operates at 355 nm with a 45-cm-aperture telescope and a matching azimuth-over-elevation scanner that provides full hemispherical pointing.To guarantee wind accuracy,a single servo loop is used to monitor the outgoing laser frequency to remove inaccuracies due to the frequency drift of the laser or the etalon.The standard deviation of the outgoing laser frequency drift is 6.18 MHz and the corresponding velocity error is 1.11 m/s.The wind profiles measured by the DWL are in good agreement with the results of the wind profile radar(WPR).Evaluation is achieved by comparing at altitudes from 2 to 8 km.The relative error of horizontal wind speed is from 0.8 to 1.8 m/s in the compared ranges.The wind accuracy is less than 6 m/s at 40 km and 3 m/s at 10 km.     

Dielectric scaling in polyelectrolyte solutions with different solvent quality in the dilute concentration regime

In this note, we present a set of radiowave dielectric spectroscopy measurements of two dilute, differently-charged polyelectrolyte solutions, under different solvent conditions. We have found that both the dielectric strength, Delta epsilon, and the relaxation time, tau(ion), of the dielectric relaxation process associated with the counterion polarization along a length scale of the order of the correlation length obey the scaling laws with the polyion concentration, according to the Ito model. This is verified with good accuracy independently of the quality of the solvent, which has been varied from poor to good solvent conditions. This finding supports evidence to the fact that, in dilute solutions, the counterion polarization is independent of the polyion concentration, in spite of what occurs at the semi-dilute concentrations.     

Radial basis function neural networks in non-destructive determination of compound aspirin tablets on NIR spectroscopy

The application of the second most popular artificial neural networks (ANNs), namely, the radial basis function (RBF) networks, has been developed for quantitative analysis of drugs during the last decade. In this paper, the two components (aspirin and phenacetin) were simultaneously determined in compound aspirin tablets by using near-infrared (NIR) spectroscopy and RBF networks. The total database was randomly divided into a training set (50) and a testing set (17). Different preprocessing methods (standard normal variate (SNV), multiplicative scatter correction (MSC), first-derivative and second-derivative) were applied to two sets of NIR spectra of compound aspirin tablets with different concentrations of two active components and compared each other. After that, the performance of RBF learning algorithm adopted the nearest neighbor clustering algorithm (NNCA) and the criterion for selection used a cross-validation technique. Results show that using RBF networks to quantificationally analyze tablets is reliable, and the best RBF model was obtained by first-derivative spectra.     

Study of lower emittance dedicated synchrotron radiation mode for the BEPCⅡ

In this paper,a dedicated synchrotron radiation （SR） mode for the BEPCⅡ with an emittance of 85 nm has been designed,including the linear lattice,chromaticity correction and dynamic aperture optimization.The emittance of the new mode is about 60% of the previous mode used for routine operation of the BEPCⅡ .The effect of wigglers on the linear lattice was compensated and the total dynamic aperture including the wigglers’ nonlinear effect was estimated.The preliminary commissioning at the end of 2008 and the formal operation with the new mode confirmed its merits.