Multi-bright-dark soliton solutions to the AB system in nonlinear optics

The AB system is the basic integrable model to describe unstable baroclinic wave packets in geophysical fluids and the propagation of mesoscale gravity flows in nonlinear optics. On the basis of the spectral analysis of a Lax pair and the inverse scattering method, we establish the Riemann–Hilbert problem of the AB system. Then, the inverse problems are formulated and solved with the aid of the Riemann–Hilbert problem, from which the potentials can be reconstructed according to the asymptotic expansion of the sectional analytic function and the related symmetry relations. As an application, we obtain the multi-bright-dark soliton solutions to the AB system in the reflectionless case and discuss the dynamic behavior of elastic soliton collisions by choosing appropriate free parameters.     

A quantum pseudodot system with two-dimensional pseudoharmonic oscillator in external magnetic and Aharonov-Bohm fields

Using the Nikiforov–Uvarov (NU) method, the energy levels and the wave functions of an electron confined in a two-dimensional (2D) pseudoharmonic quantum dot are calculated under the influence of temperature and an external magnetic field inside dot and Aharonov–Bohm (AB) field inside a pseudodot. The exact solutions for energy eigenvalues and wave functions are computed as functions of the chemical potential parameters, applied magnetic field strength, AB flux field, magnetic quantum number and temperature. Analytical expression for the light interband absorption coefficient and absorption threshold frequency are found as functions of applied magnetic field and geometrical size of quantum pseudodot. The temperature dependence energy levels for GaAs semiconductor are also calculated.     

Effects of external fields on a two-dimensional Klein-Gordon particle under pseudo-harmonic oscillator interaction

We study the effects of the perpendicular magnetic and Aharonov-Bohm(AB) flux fields on the energy levels of a two-dimensional(2D) Klein-Gordon(KG) particle subjected to an equal scalar and vector pseudo-harmonic oscillator(PHO).We calculate the exact energy eigenvalues and normalized wave functions in terms of chemical potential parameter,magnetic field strength,AB flux field,and magnetic quantum number by means of the Nikiforov-Uvarov(NU) method.The non-relativistic limit,PHO,and harmonic oscillator solutions in the existence and absence of external fields are also obtained.     

Synthesis and characterization of new hyperbranched poly(aryl ether oxadiazole)s

A new AB₂ monomer was synthesized for use in the preparation of a hyperbranched poly(aryl ether oxadiazole) with terminal phenol functionality. The AB₂ monomer contains two phenolic groups and a single aryl fluoride group that is activated toward nucleophilic displacement by the attached oxadiazole ring. The nucleophilic substitution of the fluoride with the phenolate groups led to the formation of an ether linkage. Subsequently, a hyperbranched poly(aryl ether oxadiazole) having approximately a 44% degree of branching, as determined by a combination of model compound studies and ¹H NMR, was obtained. The terminal phenolic groups underwent facile functionalization, furnishing hyperbranched polymers with a variety of functional chain ends. The nature of the chain‐end groups had a significant influence on the physical properties of the polymers, such as the glass‐transition temperature and their solubility. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 3851–3860, 2001     

NH2(X^2B1)与C2H4反应机理的从头算研究

用从头算MP2方法,在6-311G^**基组下,对NH2X^2B1)与C2H4的加成和氢迁移反应机理进行了研究,优化得到反应的过渡态,并通过振动分析和内禀反应坐标(IRC)加以证实,计算了两个反应的能垒和1500K～2000K温度范围内的速率常数。结果表明：在1500K～2000K温度范围内加成反应是NH2(XX^2B1)与C2H4的反应的主要通道,同时报道了两个反应沿反应路径变化信息。     

Hyperbranched Aromatic Polyesters

Summary: Having developed a theoretical model of hyperbranched polymerization involving AB₂ and B₂ monomers we present preliminary results of a test of its validity for the system consisting of 4,4-bis(4-hydroxyphenyl)pentanoic acid (AB₂ monomer) and bisphenol A (B₂ monomer). The monomers reacted at room temperature to yield the title hyperbranched polyesters. Diisopropylcarbodiimide (condensation water remover) along with an effective catalyst were used for that purpose. The total of AB₂ monomer was introduced at once to a reactor containing B₂ core monomer or it was divided into 3 or 5 equal portions and each of them introduced after the monomers previously present have reacted to a predetermined conversion. GPC measurements of the resulting molecular mass distribution gave inconclusive results because of poor reproducibility of polymer isolation/purification procedure and/or insufficient accuracy of GPC technique.     

AB交联聚合物的形态

以低分子量的端乙烯基聚氨酯预聚物同乙烯类单体共聚制得的AB交联聚合物(ABCP)呈现出两相形态结构,聚氨酯相形成分散相,塑料组份形成连续相。形态结构最显著特点是分散相区呈现出多分散性;其次,分散相区的形状不规则。这些特征不同于线型AB、ABA嵌段共聚物及A_2B接枝共聚物,这是由于ABCP中,A和B两组份间存在着化学交联。交联密度,预聚物的分子量对两组份的相容性,形态结构有显著影响。     

某些过渡金属钌配合物非线性光学性能的从头算和密度泛函理论研究

实验发现金属钌的某些配合物具有大的非线性光学性能。我们的理论研究表明 金属钌配合物[Ru(NH_3)_4L~DL~A]~(n+) (n = 2，3；L~D，L~A =吡啶衍生物配体) 的非线性光学性能取决于推电子基团L~D的给电子能力以及拉电子基团L~A的受电子 能力，L~D和L~A的推拉电子越强越有利于提高配合物的二阶非线性光学系数β，因 此带正电荷的L~A能大幅度提高β值。虽然增加共轭体系的长度有利于提高β值， 但在Ru的配合中，吡啶环间或吡淀环与苯环间不一定要保持共面也会有大的β值。 DFT和ab initio方法的计算结果对比表明，对于含过渡金属Ru的化合物，在HF水平 上难以得到满意的结论，由从头算有限场方法计算得到的β值偏小，而用TDDFT方 法能得到可与实验值符合较好的结果。     

蓖麻油基AB交联聚合物的介电性质

在-180℃至140℃范围内,用几个频率测定了蓖麻油基AB交联聚合物的介电松弛谱。对这些聚合物的多重松弛和相行为的研究表明,试样中的两组份在介电松弛谱上显现出相容的或近似互容的特征。试样中的次级松弛归因于聚氨酯组份中链段的局部运动。提出了一个描述界面极化的方法,计算了界面极化松弛活化能,它们同试样中组份间的相容性,界面相互作用大小以及分子链的柔曲性有关。     

双离子AB交联型聚醚类固体电解质及其电流变液的性能

将α，ω－双甲基丙烯酰氧基封端的聚乙二醇与高氯酸锂络合，分别用溶液聚合和反相悬浮聚合合成了双离子ＡＢ交联型聚醚类高分子固体电解质（ＡＢＣＰＥ２）及其组成的无水电流变（ＥＲ）液．研究了ＡＢＣＰＥ２本身的离子导电性和含ＡＢＣＰＥ２的ＥＲ液的活性和电性能，并用扫描电镜表征了ＥＲ液中的粒子．获得了离子导电率高达８．０×１０－５Ｓ／ｃｍ（２５℃）的高分子固体电解质和活性较高的无水ＥＲ液．