Structural Features of Interacting Complementary Liposomes Promoting Formation of Multicompartment Structures

The structural features of complementary liposomes and factors favoring formation of multicompartment systems are investigated. Specifically, liposomal formulations consisting of PEGylated unilamellar liposomes with guanidinium moieties located at the distal end of polyethylene glycol (PEG) chains interact with complementary multilamellar liposomes bearing phosphate moieties. Furthermore, the number of PEG chains attached to the unilamellar interface of the liposomes is enhanced by incorporating PEGylated cholesterol in their bilayer. While molecular recognition of the liposomes is the driving force for initiating multicompartmentalization, it is the enhanced PEGylation at the liposomal interface that synergistically promotes fusion resulting in large and well‐formed multicompartment systems. A mechanism is proposed according to which initial adhesion of the liposomes, followed by reorganization of their membrane lipids, leads to giant bilayer aggregates incorporating large liposomes.     

Effect of TiO2 Nanoparticles on Photochromism of WO3 Colloids

IntroductionWO3has received considerable attention becauseof its photochromic and electrochromic properties[1—10].Since the photochromic process of WO3can be com-pletely reversible by exposing it to oxygen,it has beenconsidered to be one of the most prom…     

一种高稳定性合成直链烷基苯催化剂

以具有中、大双孔结构的γ-Al2O3为载体制备了固载化AlCl3催化剂,并在悬浮床反应器中考察了其苯与1-C1=2烷基化反应活性。结果表明,该催化剂具有较高的转化率、选择性和催化稳定性。在1000小时连续反应过程中,烯烃转化率高于94%,单烷基苯选择性达到92%,其中2-苯基异构体选择性为42%。     

硅氧烷的水解-缩聚反应动力学

综述了硅氧烷的水解动力学的主要影响因素(硅氧烷上的基团和水解反应催化剂等)、单组分以及多组分硅氧烷缩聚反应动力学、硅氧烷共缩聚产物结构控制策略。     

普利沙星与Co(phen)2+3及DNA间结合作用的电化学和光谱

利用电化学和紫外光谱法研究了邻菲咯啉合钴(Co(phen)2+3)与普利沙星(PLFX)及DNA间在pH=7.4的三羟甲基氨基甲烷-盐酸缓冲溶液中的结合作用. 紫外光谱测量结果表明,普利沙星与Co(phen)2+3发生了结合作用形成二元络合物,结合常数为2.0×104 L/mol. 电化学测量表明,在Co(phen)2+3-普利沙星络合物中加入DNA后,Co(phen)2+3-普利沙星络合物的峰电流下降,峰电位差增大了17 mV,式电位负移了3.5 mV,推断络合物与DNA作用方式主要为静电作用.     

二(N,N-二乙基二硫代氨基甲酸)烷基黄原酸合钴(Ⅲ)与二丙胺和二丁胺反应的动力学

本文采用分光光度法研究了在甲醇介质中二(N,N-二乙基二硫代氨基甲酸)烷基黄原酸合钴(Ⅲ)与二丙胺,二正丁胺在298.2K～313.2K(R=Me,Et,n-Pr) 的反应动力学及机理.结果表明对配合物是准一级反应,对二正丁胺是分数级. 反应速率随着基团R的增加而减小,随着温度的增加而增加,随着溶剂中水含量的增大而增加.提出了一种含有前期平衡的反应机理.据此导出了一个能够解释实验事实的速率方程,求得了速控步骤的速率常数,并给出了相应的活化参数     

PLASMA POLYMERIZATION OF HEXAMETHYLCYCLOTRISILOXANE

In a capacitively coupled RF discharge system with external electrodes ,hexamethyicyclotrisiloxane was polymerized, and the effects of discharge power and plasma gas on polymer deposition rate were studied. The polymer structures and properties were studied by IR spectroscopy, XPS measurement, PGC/MS combined technique, TG analysis and contact angle measuring. The results showed that the polymers prepared in H_2 or O_2 have higher C/Si ratio in comparison with those prepared in inert gases. PGC/MS results revealed the existence of many short carbon chains in the polymer structure .TG analysis suggested that the polymers prepared in the inert gas would possess better thermal stabilities.     

酸催化甘油与苯甲醛缩合制备六员环缩醛

比较了对甲苯磺酸（PTSA）、磷钨酸（PWA）、KHSO₄和FeCl₃催化对甘油与苯甲醛的缩合反应收率,及对产物中六元环缩醛5-羟基-2-苯基-1,3-二氧六环(1)与五元环缩醛4-羟甲基-2-苯基-1,3-二氧五环(2)比例的影响。 当以环己烷为带水剂及苯甲醛与甘油的摩尔比为2∶3的情况下,KHSO4为催化剂的缩合产物（1+2）收率较高,为96.8%;PTSA催化的缩合产物中,化合物1的比例最高(m(1)∶m(2)=48.6∶51.4)。 室温下PTSA、PWA、KHSO₄和FeCl₃均可催化化合物2向化合物1的转化。 在-20 ℃下,只有PTSA能催化化合物2向化合物1的转化。 在-20 ℃,PTSA催化化合物[STHZ]2转化成化合物1a,并以晶体形式从苯（40%）-石油醚（60%）中析出。 母液循环转化3次后,化合物1a的累计收率可达91.1%。     

稀土对薄板坯连铸连轧工艺连铸坯组织和夹杂物的影响

采用光学显微镜、扫描电子显微镜等对薄板坯连铸连轧(CSP)工艺生产的加稀土和不加稀土的连铸坯横断面试样的微观组织变化、夹杂物的形态以及成分进行了分析,结果表明:加入稀土改变了铸态组织,利用Image Tool软件进行测量,发现稀土使铸坯表层细晶粒区由400μm扩大到630μm;通过Image Tool软件测量加稀土和不加稀土铸坯的枝晶间距,并对测量数据进行F检验分析,分析表明加入稀土对CSP连铸坯的一次枝晶间距无显著影响,对二次枝晶间距影响特别显著,使二次枝晶间距平均值由41.22μm降低到14.21μm,可靠性99%以上;加入稀土,连铸坯中的夹杂物由钙铝酸盐夹杂物或硫化物变成了球形的稀土复合夹杂物,并且降低了夹杂物的最大尺寸,使得最大尺寸由15μm左右降低到7μm左右。     

“蛙腿论战”化学史及其教学价值的探析

“蛙腿论战”是科学史上的经典事件,持久的科学争论当时以伏特发明了“伏打电堆”而结束,标志着人类自此由“静电”进入“动电”时代,同时这也被认为是电化学建立的标志。深入梳理“蛙腿论战”中理论的提出过程及其价值,对其教学价值进行探析:“蛙腿论战”充分体现了跨学科视角,并且促进对于科学本质的理解。