Molecular and Crystal Structure of 1,3,5- Tris(benzimidazol- 1-ylmethyl)-2,4,6-Trimethylbenzene

INTRODUCTIONCrystal engineering and supramolecular chemistry aimed at developing systems to perform optical, magnetic and electronic functions as well as intercalation systems for ion- or molecule-exchange and catalytic properties are some of the most attractive research areas in present years, and much progress has been achieved in both theoretical studies and their applications as new materials[1]. One of the most remarkable development in crystal engineering may be that it is possible t…     

Facile Synthesis of Chiral Conjugated Polymer Based on BINOL Skeleton

The study of polymer supported chiral catalysts has attracted very extensive attention inrecent years'. The intrinsic advantages of these catalysts in organic synthetic chemistryare that they can be separated with the products by simple filtration. Traditionally,polymer chiral catalysts are prepared by allaching chiral ligand to sterically irregularpolymer backbone2. In this system, the catalytic sites are randomly oriented along thepolymer chain which makes it very difficult to systematically…     

手性氨基酸钛螯合物的合成

用L-对甲苯磺酰氨基酸分别与四氯化钛反应,首次合成了五种L-对甲苯磺酰氨基酸钛化合物。NMR、IR和元素分析数据表明这五种手性钛化合物的结构分别是2a-2d和4,对甲苯磺酰氨基酸钛化合物在惰性气氛中可以保存数周。     

掺镁铌酸锂晶体结构的研究

通过LiNbO₃：MgO(6.7 mol/kg)晶体在常温和低温下的喇曼光谱分析,研究了掺Mg²⁺后晶体结构的变化情况．研究结果表明,常温下晶格略有畸变,个别的散射峰有耦合现象存在,随温度降低,耦合逐渐减少,但掺Mg²⁺后晶格基本结构并无变化. 关键词：     

0-3型PZT/P[VDF(77)-TrFE(23)]铁电复合物的非线性介电系数

用自建的非线性介电测试装置测得了０ － ３ 型ＰＺＴ／Ｐ［ＶＤＦ（７７） － ＴｒＦＥ（２３）］ 铁电复合物厚片在不同场强和温度下的线性和非线性介电系数。对于ＰＺＴ 体积含量Φ＞ ０ ．３ 的复合物,介电系数ε１ 随测试场强的升高显著增大。在Φ＜ ０ ．１ 时,可用Ｍａｘｗｅｌｌ－ Ｇａｒｎｅｔｔ 方程拟合实验结果。Ｂｒｕｇｇｅｍａｎ 方程适合于低电场（ ＜ １ ＭＶ／ｍ ） 下复合物介电系数的预测。随着退极化场系数Ｌｚ 的改变,用Ｙａｍａｄａ 模型可拟合不同场强下复合物介电系数随Φ的变化关系。ε１ 的温度依赖性显示了明显的热滞后效应。Φ值增大导致升温过程的居里温度Ｔｃ 降低。Φ＜ ０ ．３ 时,三阶非线性介电系数ε３ 随测试场强的升高而减小,而Φ＞ ０ ．４ 试样的ε３ 在６ＭＶ／ｍ 场强下出现极小值。高Φ值的复合物具有较大的ε３ 。高ＰＺＴ 含量的复合物在相变区出现较大的ε３值。ε３ 温度谱同样显示了与ε１ 类似的表观热滞后现象。     

The Chiral Anomalies in W and Z Decays

Some of the important W^± and Z decay amplitudes, relating to the chiral anomalies of the quark sector in the Standard Model, are given by means of the interactions determined by the effective Lagrangian (action) of the nonlinear δ model for the pseudogoldstone bosons. The corresponding decay rates are calculated. It is shown that the decay rates are quite large, especially, the rate of the decay W→πγ and probably that of W→ D₀γ are predicted being unexpectedly great (Г_W→πγ = 0.35 GeV). This indicates that the chiral anomalies and our approach should receive tests from SPPS and Tevantron experiments.