Unification of 3-3-1 models

A 3-3-1 model is constructed for three families that can be embedded into a single SU(8) unified model. Assuming appropriate branching rules and symmetry-breaking pattern, a complete fermion content is found within irreducible representations of SU(8), where light Standard Model fermions, heavy 3-3-1 fermions and superheavy fermions may be distinguished.     

Three-nucleon interaction in 3-, 4- and ∞-body systems

We report results of variational calculations of ³H, ³He, ⁴He and nuclear matter with the Urbana v₁₄ two-nucleon interaction and realistic models of the three-nucleon interaction (TNI). These include the Tucson and isobar intermediate-state models of the two-pion exchange TNI. The latter is also studied with an intermediate-range three-nucleon repulsion. In general, realistic TNI helps to bring the theory closer to experiment by giving extra binding energy to the A = 3 and 4 nuclei and providing extra saturation to the nuclear matter binding energy. The Coulomb energy of ³He and the rms radii of A = 3, 4 nuclei are also well described. However, some problems remain unresolved. There is a slight overbinding of ⁴He, an underbinding of nuclear matter, and the charge form factors of ³He and ⁴He, calculated with impulse approximation, deviate from the experimental at q²>5 fm^?2.     

Study of ω-, η-, η′- and D-mesic nuclei

Using the quark-meson coupling (QMC) model, we investigate whether ω, η, η′ and D⁻ mesons form meson-nucleus bound states. Our results suggest that one should expect to find η- and ω-nucleus bound states in all the nuclei considered. Furthermore, it is shown that the D⁻ meson will form quite narrow bound states with ²⁰⁸Pb.     

Torsional barriers and nonlinear optical properties of 2-, 3-, 4-phenylpyridine molecules

The torsional barriers and nonlinear optical properties for all phenylpyridine molecules were calculated by using Hartree-Fock (HF) theory and Becke three-parameter functional (B3LYP) hybrid approaches within the density functional theory framework with the 6-31++G(d, p) basis set, and via the GAUSSIAN 98W. The torsional barrier computations show that dihedral angle between the two rings increases with the number of H-H vicinal interactions and torsional barriers with dihedral angles for 3-, 4-phenylpyridines are too similar for both HF and B3LYP level calculations. Also, HOMO-LUMO energy gaps, polarizabilities, anisotropy of polarizabilities, and static hyperpolarizabilities are calculated as a function of dihedral angle between benzene and pyridine rings. The study reveals that the phenylpyridines show very low nonlinear optical properties. The calculated torsional barrier, equilibrium dihedral angle and molecular dipole moment results for these molecules were compared with available experimental and other results determining from different computational methods.     

手性分子2, 3-丁二醇的旋光拉曼光谱研究

本文从拉曼峰和旋光拉曼峰出发,通过键极化率和微分键极化率分析研究(2R, 3R)-2, 3-丁二醇. 通过分子C₁和C₂两种点群的优化结构,获得不依赖于这两种结构的结果 和有关这个手性系统物理图像的丰富信息.对分子拉曼键极化率分析,得出在拉曼弛豫过程中, 电荷主要从外围流向骨架结构.对分子微分键极化率的分析,显示在不对称C原子和与其相联系的H原子 两侧化学键, C-O和C-CH₃的微分键极化率的符号正好相反,意味着这个分子具有相当好的手性 不对称性质.对比对称和反对称的键极化率、微分键极化率,本文得到这样的结论: 对于(特别是键伸缩的)键极化率,(大体上是)对称的大于反对称的; 而对于微分键极化率则是反对称的大于对称的. 关键词： 旋光拉曼 键极化率 微分键极化率 2,3-丁二醇     

Features of dual fluorescence of 1, 2, 3, 4- tetrahydroisoquinoline

In polar and nonpolar solvents, tetrahydroisoquinoline emits S₂ (ππ¹) → S₀ and S₁ (ππ¹) → S₀ dual fluorescence and T₁ (ππ¹) → S₀ phosphorescence on S₂ (ππ¹) ← S₀ excitation. When excited by S₁ (ππ¹) ← S₀ the molecule yields S₁ (ππ¹) → S₀ fluorescence and T₁ (ππ¹) → S₀ phosphorescence in nonpolar solvent but only fluorescence in polar solvents. Probable participation of intermediate S₁ (nπ¹), T₁(nπ¹) states in intersystem crossing and internal conversion processes and its significance in interpreting the results are discussed.     

Concerning the Landau pole in 3-3-1 models

Some 3-3-1 models predict the existence of a non-perturbative regime at the TeV scale. We study in these models and their supersymmetric extensions, the energy at which the non-perturbative limit and a Landau-like pole arise. An order of magnitude for the mass of the extra neutral vector boson, , present in these models is also obtained.Received: 12 October 2004, Revised: 1 November 2004, Published online: 21 December 2004PACS: 12.60.Cn, 12.60.Jv     

Efficient synthesis of alkyl 2-[2-(arylcarbonylimino)-3-aryl-4-oxo-1, 3-thiazolan-5-ylidene]-acetates

Reaction of 1-aryl-3-arylcarbonylthioureas with dialkyl acetylenedicarboxylates in CH₂Cl₂ at room temperature leads to alkyl 2-[2-(arylcarbonylimino)-3-aryl-4-oxo-1,3-thiazolan-5-ylidene]-acetates in good yields.     

基于水内标的NO-3，SO2-4，ClO-4拉曼光谱定量分析研究

拉曼光谱由于重现性差,在进行定量分析时往往需要内标。在水溶液中,水在2 700~3 900 cm-1范围伸缩振动拉曼峰很强,有作为内标的可能性,但水与溶质的相互作用会导致水伸缩振动拉曼峰形状发生变化,此外水的占比也会随着溶质浓度的变化而变化,当溶质浓度较高时需要对水的含量进行校正。将这两点因素考虑在内,研究了以水为内标,采用拉曼光谱法测量水溶液中NO-₃,SO2-₄和ClO-₄浓度的适用性。不同浓度NaNO₃,Na₂SO₄和NaClO₄溶液的拉曼光谱显示随着盐浓度的升高水在2 700~3 900 cm-1范围内的拉曼峰呈现出左肩下降右肩上升的变化趋势。将三种盐溶液拉曼光谱中酸根离子拉曼峰面积（A_盐）和水的拉曼峰面积（A_H2O）的比值（Ｒ_S=A_盐/A_H2O）与溶液中酸根离子和水的含量的比值（c_盐/c_H2O）作图,均呈现出良好的线性关系,拟合得到三条相关曲线的R2分别为0.999 1,0.999 1和0.999 4,说明酸根离子和水的拉曼散射系数均未发生变化或者在同比例变化。虽然水拉曼峰的形状发生了改变,但并不会影响水作为内标的可行性。在引入水的含量修正后,经理论推导c_盐与R_S符合关系式：c_盐=AR_S/(1+BR_S)。在0.1 mol·L-1到近饱和的宽浓度范围内,将R_S对c_盐作图,通过数据拟合获得的NaNO₃,Na₂SO₄和NaClO₄的工作曲线分别为c_NaNO3=18.8R_S/(1+0.6R_S) (R2=0.999 1),c_Na2SO4=20.2R_S/(1+1.0R_S) (R2=0.998 8),c_NaClO4=15.0R_S/(1+0.7R_S) (R2=0.999 8)。NaNO₃,Na₂SO₄和NaClO₄的检出限分别为0.008 0,0.005 2和0.007 3 mol·L-1。在水拉曼峰形状变化不影响其作内标可行性的基础上,当溶液中同时存在两种阴离子时,通过在水含量修正部分加入干扰离子对水含量的影响,可以在单盐溶液定量工作曲线中加入校正项来消除溶液中干扰离子对待测离子分析结果的干扰,但当干扰离子浓度较大而待测离子浓度较小时,干扰离子拉曼峰强度过大会影响到待测离子拉曼峰面积的准确性,从而使得校正的效果下降。