简单多原子无机共价分子的“键类数”计算及应用

本文提出了计算简单多原子无机共价分子中不同键型(σ键、π键和孤对电子——非键)键数目——“键类数”的方法,建议了几个计算“键类数”的简单公式,并讨论了它们在利用价层电子对排斥理论推断分子几何构型,确定分子的路易斯结构和判断分子中是否可能有非定域大π键形成等方面的应用。

三聚阴离子表面活性剂/阳离子添加剂混合体系的流变行为

表面活性剂的分子结构对蠕虫胶束的形成与性质有着重要影响。本文以十四酸和间苯三酚为起始原料,合成了一种三聚阴离子表面活性剂(2,2′,2′′-(苯基-1,3,5-三(氧))-三-十四酸钠,简写为Ph-TrisC_(14)Na),并通过稳态和动态流变测试,研究了单组分的Ph-TrisC_(14)Na和Ph-TrisC_(14)Na/阳离子添加剂体系的粘弹性质。阳离子添加剂分别为正丁基三甲基溴化铵(C_4TAB),正己基三甲基溴化铵(C_6TAB)和正辛基三甲基溴化铵(C_8TAB)。结果表明,依赖于独特的分子构型,Ph-TrisC_(14)Na分子自身即可形成蠕虫胶束,使溶液表现出明显的粘弹性。阳离子添加剂的加入可进一步优化Ph-TrisC_(14)Na的分子几何结构,促进蠕虫胶束更为快速地生长。随着阳离子添加剂疏水链长的增加,溶液的粘弹性显著增强,体系微结构对添加剂的敏感性也增加。对于50 mmol?L^(-1)的Ph-TrisC_(14)Na溶液来说,在C_8TAB与Ph-TrisC_(14)Na的摩尔比为0.5时,体系的零剪切粘度可达1535 Pa?s,蠕虫胶束的长度则达到4.0-7.5μm。该体系体现出低聚表面活性剂在构筑表面活性剂粘弹溶液方面的优势,可拓展高粘弹性阴离子蠕虫胶束体系的研究范围。

On structure of cluster algebras of geometric type Ⅰ：In view of sub-seeds and seed homomorphisms

Our motivation is to build a systematic method in order to investigate the structure of cluster algebras of geometric type. The method is given through the notion of mixing-type sub-seeds, the theory of seed homomorphisms and the view-point of gluing of seeds. As an application, for(rooted) cluster algebras, we completely classify rooted cluster subalgebras and characterize rooted cluster quotient algebras in detail. Also,we build the relationship between the categorification of a rooted cluster algebra and that of its rooted cluster subalgebras. Note that cluster algebras of geometric type studied here are of the sign-skew-symmetric case.