Capture by stabilized continuum: Classical and quantum aspects

We review here the results of our investigations concerning chaotic atomic scattering in the presence of a laser field. Particular emphasis is put on the existence of classical stable resonance structures, induced by the intense laser field, which are embedded in the field-free continuum. We show that phase space structures in the vicinity of a resonance island play an important role in the chaotic scattering behavior and form the basis for a mechanism to enhance the lifetimes of the collisional partners. Quantum calculations, based on a wave packet propagation method, show that quantum solutions are strongly influenced by the classical phase space structures. More specifically, a wave packet is found to spread differently in the regular and chaotic regions; in the latter case it spreads exponentially with time until saturation occurs, defining the saturation time. We also investigate the dependence of the spreading rates in both the regular and chaotic regimes. Calculations with an ensemble of classical trajectories are also presented to further illustrate the smoothing effects of varying.     

An Efficient Method for the Synthesis of Acyl-diazenes Using NaNO_2/NaHSO_4·H_2O

Azo compounds are widely utilized as analytic reagents and dyes1, they can also be used in material of non-linear optics, material of optics information storing in laser disks, and dyes with oil solubility in photochromy in modern technology2. Recently, many noteworthy studies have shown that some azo compounds possess excellent optical memory and photoelectric properties3,4. For example, polymer scaffolds bearing azobenzene-potential are useful for optical information storage, azo-dye doped…     

月桂树叶中蛋白质的提取工艺研究

桂花(Osmanthus fragrans Lour)是木犀属植物,原产我国,属我国传统十大名花之一,素以香花著称.桂花喜湿润,亦耐旱;喜阳光,亦耐阴;喜温暖,亦耐寒[1].叶是植物进行光合作用和蒸腾作用的主要部位,与周围环境有密切关系.桂花叶形较小,革质.     

水中3-甲基-6-氨基-5-氰基-4-芳基-1-苯基-1，4-二氢吡喃[2，3-c]吡唑的洁净合成

在水溶剂中并有三乙基苄基氯化铵（TEBA）存在下，取代芳亚甲基丙二腈与3- 甲基-1-苯基-2-吡唑啉-5-酮缩合成为3-甲基-6-氨基-5-氰基-4-芳基-1-苯基-1， 4-二氢吡喃[2,3-c]吡唑，此法为相应化合物的合成提供了一种快速、方便、高效 和洁净的方法。     

溶剂热法制备Ag/TiO2纳米材料及其光催化性能

以乙醇为溶剂, 钛酸四丁酯为前驱体, 用溶剂热法制备了Ag表面修饰的负载型纳米二氧化钛光催化剂. 利用X射线衍射(XRD)、N₂吸附-脱附(BET)、透射电子显微镜(TEM)、X射线光电子能谱(XPS)、紫外-可见(UV-Vis)光谱等技术对其进行了系统的表征, 以亚甲基蓝(MB)溶液的脱色降解为模型反应, 考察了不同Ag含量样品的光催化性能. 结果表明: 用溶剂热法制备的样品中TiO₂皆为锐钛矿相, 金属Ag颗粒沉积在TiO₂表面, 粒径为2 nm左右, 比表面积较溶胶凝胶法制备的样品大大增加, 最高可达151.44 m²·g^-1; UV-Vis光谱和光催化实验表明: Ag修饰使TiO₂对光的吸收能力大大增强, 吸收带边红移至可见光区, 亚甲基蓝在该复合材料上的光催化降解反应遵循一级反应动力学模型; 溶剂热法制备样品的光催化性能明显好于溶胶凝胶法制备的样品, 在紫外光和可见光下, Ag摩尔分数为5%的样品表现出最佳的光催化活性.     

A study of a nonprimitive model for electrolyte solutions based on perturbation theory

The equation for the Helmholtz free energy for systems of small anisotropic molecules and ions is deduced by substituting the complete expression for various potential energies (including repulsive, dispersive, electrostatic, and induced energies) into the perturbation expansion. The equation is applied to pure water. The relative dielectric constant is set at unity. Based on the equal chemical potentials of equilibrated vapor and liquid phases, the molecular parameters of water are regressed from the densities of saturated vapor in the temperature range of 0 to 370°C. The ARD of regression is 1.16%. These parameters are used to predict the heat of vaporization and densities of saturated vapor and liquid phases of water in the same temperature range. The ARDs of prediction are 4.5% and 9.8%, respectively. The equation is used to correlate the osmotic coefficients of twelve 1:1 electrolyte solutions. The relative dielectric constant is set at unity. The parameters (Soft-sphere diameter and dispersive constant) of seven ions (Na⁺, K⁺, Rb⁺, Cs⁺, Cl^–, Br^–, and I^–) are obtained. The total average absolute deviation between calculated and experimental values of the osmotic coefficient is 0.041. The parameters of ions can keep constant in different systems.     

Rapid chiral analysis based on liquid-phase cyclic chemiluminescence

Rapid chiral analysis has become one of the important aspects of academic and industrial research. Here we describe a new strategy based on liquid-phase cyclic chemiluminescence (CCL) for rapid resolution of enantiomers and determination of enantiomeric excess (ee). A single CCL measurement can acquire multistage signals that provide a unique way to examine the intermolecular interactions between chiral hosts and chiral guests, because the lifetime (τ) of the multistage signals is a concentration-independent and distinguishable constant for a given chiral host–guest system. According to the τ values, CCL allows discrimination between a wide range of enantiomeric pairs including chiral alcohols, amines and acids by using only one chiral host. Even the chiral systems hardly distinguished by nuclear magnetic resonance and fluorescence methods can be distinguished easily by CCL. Additionally, the τ value of a mixture of two enantiomers is equal to the weighted average of each enantiomer, which can be used for the direct determination of ee without the need to separate the chiral mixture and create calibration curves. This is extremely crucial for the cases without readily available enantiomerically pure samples. This strategy was successfully applied to monitoring of the Walden inversion reaction and analysis of chiral drugs. The results were in good agreement with those obtained by high-performance liquid chromatography, indicating the utility of CCL for routine quick ee analysis. Mechanism study revealed that the τ value is possibly related to the activity of the chiral substance to catalyze a luminol–H₂O₂ reaction. Our research provides an unprecedented and general protocol for chirality differentiation and ee determination, which is anticipated to be a useful technology that will find wide application in chirality-related fields, particularly in asymmetric synthesis and the pharmaceutical industry.

Rapid chiral analysis has become one of the important aspects of academic and industrial research.