When Glass and Metal Corrode Together,V: Sodium Copper Formate

A sodium copper formate, first described in 2002, can also form on copper alloys with sodium originating from soda glass hydrolysis. The frequent occurrence (50% of 250 cases of glass-induced metal corrosion) is due to the presence of formaldehyde emissions in storage and its direct reaction to formate in the alkaline surface films. The compound can be produced without the presence of acetate when chalconatronite or metal coupons immersed in soda solution are exposed to formaldehyde vapours. The crystal structure, derived from X-ray powder diffraction, yielded the sum formula Cu₄Na₄O(HCOO)₈(OH)₂·4H₂O. Except for the absence of acetate in the structure, this is in good agreement with the 2002 publication. To assess which kind of combined glass/metal objects are affected, a number of large museum collections were surveyed. Sodium copper formate was detected as a corrosion product using mainly micro-Raman spectroscopy, for instance, on 18 painted Limoges enamels, eight glass vessels with metal mountings, glass beads on metal wire from 11 bridal crowns, nine Christmas tree balls with wire decoration, 40 pieces of jewellery with glass gems, three daguerreotypes, and one miniature with cover glasses.     

活性炭吸附PMo12催化合成乙酸环己酯

本实验以乙酸和环己醇为原料，用活性炭吸附12-磷钼酸作催化剂合成了乙酸环已酯，探讨了醇酸摩尔比、催化剂用量、反应时间、带水剂用量对酯化产率的影响，考察了催化剂重复使用效果，确定了最佳实验条件．     

硫酸氢钠催化合成乙酸乙酯

在一水硫酸氢钠存在下由乙醇与乙酸酯化合成乙酸乙酯。研究了乙醇、乙酸与硫酸氢钠摩尔比、反应时间对其收率的影响。当乙酸、乙醇和硫酸氢钠的物质的量之比为1：1．65：0．073，回流1h，酯收率达到57．4％。     

苯甲酸乙酯制备实验的改进

实验绿色化是目前大学化学实验教学改革与研究的热点和方向之一.苯甲酸乙酯制备是典型的有机实验,本文采用自行设计的回流-吸水反应装置,一水硫酸氢钠为绿色催化剂,考察了反应时间、催化剂用量对酯化反应产率的影响.结果表明:改进后的实验具有装置简单、操作方便、收率高和实验绿色化的特点.     

头孢他啶侧链酸乙酯合成工艺研究

以去甲氨噻肟酸乙酯为原料,在碱性条件下与α-澳代异丁酸叔丁酯合成了头孢他啶侧链酸乙酯,分析了不同溶剂、碱的用量对反应收率的影响．较佳的反应条件为：溶剂DMF350mL,摩尔比为去甲氨噻肟酸乙酯：α-澳代异丁酸叔丁酯：无水碳酸钾=1：1．2：2,反应温度45℃,反应时间24h．在此条件下,反应收率达89．6％．     

Induction of experimental acute ulcerative colitis in rats by administration of dextran sulfate sodium at low concentration followed by intracolonic administration of 30% ethanol

Several models of experimental ulcerative colitis have been reported previously. However, none of these models showed the optimum characteristics. Although dextran sulfate sodium-induced colitis results in inflammation resembling ulcera-tive colitis, an obvious obstacle is that dextran sulfate sodium is very expensive. The aim of this study was to develop an inex-pensive model of colitis in rats. Sprague-Dawley rats were treated with 2% dextran sulfate sodium in drinking water for 3 d fol-lowed by an intracolonic administration of 30% ethanol. The administration of 2% dextran sulfate sodium followed by 30% ethanol induced significant weight loss, diarrhea and hematochezia in rats. Severe ulceration and inflammation of the distal part of rat colon were developed rapidly. Histological examination showed increased infiltration of polymorphonuclear leukocytes, lymphocytes and existence of cryptic abscesses and dysplasia. The model induced by dextran sulfate sodium at lower concentra-tion followed by 30% ethanol is characterized by a clinical course, localization of the lesions and histopathological features similar to human ulcerative colitis and fulfills the criteria set out at the beginning of this study.     

两种常见合成乙酸乙酯的方法比较

高职高专实验中,醋酸乙酯的制备实验在有机化学实验课本中是一个比较重要、也是最基本的实验操作。主要原理是利用冰醋酸和无水乙醇在浓硫酸的作用下制取乙酸乙酯,在操作时应控制好反应时的温度。但实验存在很多的不足之处,如浓硫酸在催化过程中,由于温度过高,使得部分反应物炭化,造成乙酸乙酯产率的降低等。基于此原因,对传统制取乙酸乙酯的方法和微波辐射法合成乙酸乙酯做了详细的对比,发现后者有明显的优势,而且在培养学生节约、环保的意识方面起到了积极的作用。     

食品中亚硫酸盐测定方法的改进

采用无毒的三乙醇胺替代有剧毒的四氯汞钠溶液对食品中测定亚硫酸盐的国标方法（GB5009.34-2003）进行了改进.结果表明,在相同的实验条件下,使用三乙醇胺替代了四氯汞钠,操作简便,环境友好,检测效果好.     

醋酸纤维素酯电影胶片贮存条件探讨

醋酸纤维素酯电影胶片是目前保存较多的一类电影胶片,由于自身构成材料与保存环境因素的影响,在使用与保存过程中容易出现霉变、褪色、醋酸综合症等病害现象,因此选择适宜的保存条件预防病害现象的发生对于保存醋酸纤维素酯电影胶片尤为重要.本文基于电影胶片的构成材料与保存环境对电影胶片的作用,探讨醋酸纤维素酯电影胶片适宜的保存条件.     

氯化钠侵蚀环境下固化疏浚土宏微观力学特性试验

为研究固化疏浚土在氯化钠侵蚀环境下的工程特性,以上海市南汇东滩某吹填场地的黏质粉土为试验土料,掺入自制固化剂制备固化疏浚土试块,进行氯化钠浸泡试验,研究氯化钠初始质量浓度和浸泡龄期对试块抗压强度的影响。采用扫描电镜拍摄试块表面微观结构照片;采用Image-Pro Plus (IPP)图像处理技术结合MATLAB分析程序得到与颗粒和孔隙相关的微观结构参数;基于分形理论,研究氯化钠初始质量浓度、分形维数和抗压强度三者之间的宏微观关联。结果表明:试块的抗压强度随着氯化钠初始质量浓度和浸泡龄期的增长而增长;氯化钠初始质量浓度的增加会引起分形维数的变化,进一步影响试块的宏观抗压强度,三者之间存在内在的定量关联。