量子点显示——中国显示行业“换道超车”的曙光

用量子点进行显示具有高性能、低成本等优势.作为一项“颠覆性技术”,量子点显示将在显示行业掀起一场技术革命,为我国显示产业突破国外技术和专利封锁,占据产业科技制高点,实现“换道超车”提供了良好的契机.主要介绍了量子点发光显示关键材料与器件研究的相关进展,以及其在中国显示行业的应用现状与前景.     

荧光光谱结合支持向量机测定食用色素纯度

采用一种由原点矩法改造所得的特征压缩算法对荧光光谱数据进行预处理,将处理后的数据与加权最小二乘支持向量机(WLS-SVM)算法结合,建立鲁棒回归模型,用以预测实际食用色素粉末的纯度。以亮蓝和胭脂红这2种色素为例论述该方法对实际食用色素粉末纯度的预测效果。首先,利用FLS920荧光光谱仪测量获得两种色素的标准样本和实际样本在最佳激发波长下的荧光发射光谱数据,利用由原点矩法改造所得的特征压缩算法对获取的荧光光谱数据进行压缩和变换,一方面缩短了算法的运算时间,另一方面也提高了模型的预测精度。将预处理后的荧光光谱数据输入加权最小二乘支持向量机中建立浓度预测模型,该模型对亮蓝、胭脂红实际样本溶液给出的预测光谱与它们的实测光谱吻合程度好,半高峰宽区间内的平均决定系数分别为0.662和0.931。所有亮蓝、胭脂红溶液的预测浓度和标称浓度之间具有良好的线性关系,相关系数分别为0.997和0.992。由此通过多项式拟合得到的亮蓝、胭脂红粉末的预测纯度分别为61.0%和72.3%。     

高纯硅中补偿性杂质的光热电离光谱

首先测量了高纯n型硅样品在接近液氦温度区域内随温度变化的光热电离光谱，确定了硅样品的最佳光热电离温度范围. 在该温度范围内，在有本征带隙光照射条件下，测量了样品的高分辨率光热电离光谱，同时观察到了来自主要浅杂质施主磷以及补偿性杂质硼的正信号. 随后，应用外加磁场，对硼的光热电离光谱进行了研究，发现来自硼的光热电离信号，在外加磁场作用下，发生了由正向负信号的转变. 通过对该现象进行分析讨论，排除了该现象是温度效应的可能，指出普遍用来解释补偿性杂质光热电离响应的Darken模型存在不足，而少数载流子快速复合模     

Analysis of dynamical properties for the two-site Bose Hubbard model with an algebraic method

In this work, we propose an algebraic recursion method to study the dynamical evolution of the two-site Bose- Hubbard model. We analyze its properties from the viewpoints of single partite purity, energy, and trace distance, in which the model is considered as a typical bipartite system. The analytical expressions for the quantities are derived. We show that the purity can well reflect the transition between different regimes for the system. In addition, we demonstrate that the transition from the delocalization regime to the self-trapping regime with the ratio r/increasing not only happens for an initially local state but also for any initial states. Furthermore, we confirm that the dynamics of the system presents a periodicity for η = 0 and the period is tc =π/2J when the initial state is symmetric.     

质谱中的立体化学效应（19）──对映异构的α－苯乙胺光学纯度质谱测定

质谱中的立体化学效应（１９）──对映异构的α－苯乙胺光学纯度质谱测定吴忆南，涂亚平，潘远江，陈耀祖（浙江大学化学系，杭州，３１００２７，兰州大学应用有机化学国家重点实验室）崔勐，宋凤瑞，刘淑莹（中国科学院长春应用化学研究所）关键词对映体，光学纯度，质...     

A Method to Assess Radiochemical Purity of Compounds Measured by Radioimmunoassay

Abstract

A method is described for assessing radiochemical purity of compounds measured by radioimmunoassay. This method is applicable in cases when chromatography is used prior to the radioimmunoassay proper. In individual fractions of the chromatographic zone containing the compound assayed, both radioactivity (e. g. in DPM) and mass (e. g. in pg) are measured. The measurement of mass is performed using radioimmunoassay. Radiochemical purity is assumed, if the radioactivity/mass ratio (specific activity) in individual fractions of the zone is constant. The constancy of specific activity is tested statistically using a regression analysis. A radioimmunoassay of progesterone in a blood plasma pool collected during the follicular phase of the menstrual cycle was used to demonstrate the practical features of the assessment of radiochemical purity. Radiochemical pure progesterone could be obtained only after repeated chromatography. Purification to radiochemical purity resulted in a significantly decreased estimate of progesterone contents in the plasma pool investigated. A value of 344 pg/ml was obtained, in contrast to the value of 422 pg/ml found prior to the repeated chromatography. The former value can be considered an accurate and valid estimate.     

Enantiomeric separation of some common controlled stimulants by capillary electrophoresis with contactless conductivity detection

CE methods with capacitively coupled contactless conductivity detection (C⁴D) were developed for the enantiomeric separation of the following stimulants: amphetamine (AP), methamphetamine (MA), ephedrine (EP), pseudoephedrine (PE), norephedrine (NE) and norpseudoephedrine (NPE). Acetic acid (pH 2.5 and 2.8) was found to be the optimal background electrolyte for the CE‐C⁴D system. The chiral selectors, carboxymethyl‐β‐cyclodextrin (CMBCD), heptakis(2,6‐di‐O‐methyl)‐β‐cyclodextrin (DMBCD) and chiral crown ether (+)‐(18‐crown‐6)‐2,3,11,12‐tetracarboxylic acid (18C6H₄), were investigated for their enantioseparation properties in the BGE. The use of either a single or a combination of two chiral selectors was chosen to obtain optimal condition of enantiomeric selectivity. Enantiomeric separation of AP and MA was achieved using the single chiral selector CMBCD and (hydroxypropyl)methyl cellulose (HPMC) as the modifier. A combination of the two chiral selectors, CMBCD and DMBCD and HPMC as the modifier, was required for enantiomeric separation of EP and PE. In addition, a combination of DMBCD and 18C6H₄ was successfully applied for the enantiomeric separation of NE and NPE. The detection limits of the enantiomers were found to be in the range of 2.3–5.7 μmol/L. Good precisions of migration time and peak area were obtained. The developed CE‐C⁴D method was successfully applied to urine samples of athletes for the identification of enantiomers of the detected stimulants.     

Monitoring the Dynamics of Phase Separation in a Polymer Blend by Confocal Imaging and Fluorescence Correlation Spectroscopy

The phase separation of the polymer blend polystyrene/poly(methyl phenyl siloxane) (PS/PMPS) is studied in situ by laser scanning confocal microscopy (LSCM) and by fluorescence correlation spectroscopy (FCS) at macroscopic and microscopic length scales, respectively. It is shown for the first time that FCS when combined with LSCM can provide independent information on the local concentration within the phase‐separated domains as well as the interfacial width.     

Application Of Fluorescamine Xiv1. Determination Of Optical Purity Of A Small Amount Of Amino Acids By The Fluorescamine Method

Abstract

A new simple and fast micro method has been established to determine the optical purity of a small amount of amino acids (0.1–1 μg/ml). The amino acids react readily with fluorescamine to form pyrrolinone-type chromophores, which show strong CD bands at 400–300 nm and much larger optical rotation than the free amino acids in the visible spectral range.     

Study on Quantum Entanglement Between Mesoscopic Circuit and Environment at Coherent State

Taking into account the interaction between electrons and phonons, in the case without-rotating-wave approximation, we study the entangling property between the mesoscopic circuit and environment at coherent state or equilibrium state. The result indicates that, in long time limit t→∞, the averages of charge and current in the circuit only depend on the average of the system at the initial state when the environment is initially at thermal equilibrium. However, when the environment is initially at coherent state, the average of charge and current in the circuit is determined by the specific coherent state ensemble. Generally speaking, the entanglement between the circuit and environment will lead to the quantum state purity declining of the circuit, then the circuit emerges decoherent phenomenon, and so a mixed state appears. Purity changes are related to the initial quantum state of environment and circuit. With the further evolution of time, coherence will be gradually restored, but cannot return to 1.