The impact of chloride desalination on the corrosion rate of archaeological iron

Abstract

Although desalination of archaeological iron reduces its chloride concentration and enhances object stability, the reduction in corrosion rate that this produces has never been quantified. This study measures post-treatment corrosion rates in accelerated corrosion environments to identify the impact of removing chloride ions on corrosion rate. Thirty-five archaeological iron nails, treated individually in either alkaline sulphite or nitrogen-deoxygenated sodium hydroxide, were exposed to 75°C and 75% relative humidity together with 31 untreated objects from the same archaeological sites. Object weight change and visual examination of physical change before and after the test period were used to monitor corrosion. 77% of treated objects showed no weight gain and no visible signs of corrosion, while 90% of untreated objects did corrode. The impact of chloride on corrosion of untreated objects was clearly established by a significant linear correlation between chloride content and weight gain. Treated objects with <400 ppm chloride content showed no corrosion behaviour. Corrosion of treated objects was attributed to incomplete treatment: 93% of objects treated to <5 mg/l Cl^? in the final solution bath displayed no corrosion behaviour. Based on these results, desalination of iron objects to enhance their stability offers a valuable option for reducing corrosion rates of archaeological iron, which should increase object lifespan. The results also raise the question of whether low levels of post-treatment residual chloride produce corrosion of any significance. Answering this will be an important step forward for managing the preservation of archaeological iron.     

Differential thermal expansion as a cause of salt decay: literature review,experiments, and modelling of micro and macro effects on Ançã limestone

Salt decay is one of the harshest, most frequent, and more complex types of decay of porous materials in built heritage, including natural stones, ceramics, and mortars. In this article, we address the mechanism of thermal expansion, which is one of the least studied, yet most controversial, of those proposed over time to explain salt decay. We present a review of scientific literature on the topic, followed by a study of the effects of thermal expansion on a specific material, the well-known Ançã limestone. The study included experimental measurement of the linear thermal expansion coefficient of the Ançã, both in its natural state and with varying contents of sodium chloride, sodium sulphate, or sodium nitrate. The results show that this coefficient: (i) is significantly higher when the stone is contaminated with salt; and (ii) scales approximately with the amount of salt contained in the stone pores, regardless of the type of salt. Based on these results and on modelling of damage modes at the microscopic and macroscopic levels, respectively, we conclude that thermal expansion can cause powdering, disaggregation, or other types of decay consisting of internal loss of cohesion. However, it is not likely to cause exfoliation of salt-loaded layers.     

偏钒酸钠对小鼠耳廓微循环的影响

小鼠分别经腹腔注射０．３３、１．００、３．００ｍｇ·ｋｇ－１的偏钒酸钠（ＮａＶｏ３），小鼠染毒后第二、四、六周末每组随机抽取５只小鼠观察耳廓微静脉管径、血流速度及流态的变化。结果表明，染毒第四、六周末３．００ｍｇ·ｋｇ－１组血管管径减小、血流速度减慢，与对照组比较均有显著性差异（Ｐ＜０．０５）。另外，染毒六周末１．００ｍｓ·ｋｇ－１组血管管径也明显减小（Ｐ＜０．９５）；四周末１．００ｍｓ、ｋｇ－１组血流速度也减慢（Ｐ＜０．０５）。流态均无改变。     

不同免疫生长促进剂对蛋公鸡增重和性腺发育的影响

选择 2 10只 1日龄新罗曼商品健康公鸡 ,随机分为 3组 ,每组 70只 ,研究日粮添加免疫生长促进剂C96和亚硒酸钠对鸡增重和睾丸发育影响。结果表明 :(1) 12 0d试验期 ,Se组 (0 .6 5mgSe/kg饲料 )和C96组 (11mgC96/kg饲料 )鸡体重均高于对照组 ,Se组 95d时显著性差异 (P <0 .0 5 ) ;Se组和C96组鸡体重和日增重差异不显著。 (2 )各组鸡睾丸发育均呈持续增长 ,睾丸重和睾丸相对系数 (睾丸重 /体重 ) ,30 - 95dSe组和C96组鸡均高于对照组 ,6 5d和Se组鸡睾丸相对系数显著高于对照组 (P <0 .0 5 ) .C96组鸡睾丸发育强度有高于Se组的趋势 ,但差异不显著 (P >0 .0 5 )。     

Effects of vanadate on the activities of mice glucokinase and hexokinase

This study aimed at acquiring knowledge on the hypoglycemic mechanisms of sodium metavanadate (SMV)showed that the liver glucokinase and muscle hexokinase activities increased rapidly after oral SMV was given, and that the blood glucose level was correlated closely with the activities of the two enzymes but not with the insulin level; which indicated that SMV could improve the altered glucose phosphorylation in diabetic mice independently of stimulating insulin secretion. This was probably one of the mechanisms of hypoglycemic effects of SMV.     

头孢哌酮钠中有机溶剂残留量的测定

建立了采用直接进样毛细管气相色谱法测定头孢哌酮钠中丙酮和正丁醇残留量的方法.色谱柱为DB-1石英毛细管柱,柱温为150℃,载气为氮气,检测器为FID,以DMF为溶剂.在上述色谱条件下,丙酮和正丁醇的线性范围为10~90 mg/L,平均加样回收率分别为100.53%和99.28%.本方法简便、专属性强、准确度高,可用于测定原料药中丙酮和正丁醇的残留量.     

头孢替唑钠合成路线图解

头孢替唑钠2002年开始在我国应用,用量逐年增长,目前国内生产厂家较少。头孢替唑钠的分子结构中,头孢烯酸的7_氨基部分连接的为1H_1_四氮唑乙酰基(A部分),3_亚甲基部分连接的为1,3,4_噻二唑_2_硫醚基(B部分),我们根据其A、B部分在合成过程中引入的先后顺序,对其合成路线进行了图解。     

Sodium arsenite reduces severity of dextran sulfate sodium-induced ulcerative colitis in rats

The histopathological features and the associated clinical findings of ulcerative colitis (UC) are due to persistent inflammatory response in the colon mucosa. Interventions that suppress this response benefit UC patients. We tested whether sodium arsenite (SA) benefits rats with dextran sulfate sodium (DSS)-colitis. The DSS-colitis was induced by 5% DSS in drinking water. SA (10 mg/kg; intraperitoneally) was given 8 h before DSS treatment and then every 48 h for 3 cycles of 7,14 or 21 d. At the end of each cycle rats were sacrificed and colon sections processed for histological examination. DSS induced diarrhea, loose stools, hemoccult positive stools, gross bleeding, loss of body weight, loss of epithelium, crypt damage, depletion of goblet cells and infiltration of inflammatory cells. The severity of these changes increased ir the order of Cycles 1,2 and 3. Treatment of rats with SA significantly reduced this severity and improved the weight gain.     

平阳霉素与鱼肝油酸钠治疗肝血管瘤临床观察

目的：探讨平阳霉素碘油乳剂（PLE）与鱼肝油酸钠治疗肝血管瘤的疗效、安全性、患者的耐受程度。方法：每组随机选择各10例肝血管瘤患者，分别用PLE及鱼肝油酸钠栓塞，观察每组患者栓塞后的临床反应及表现，比较其栓塞效果。结果：1．用PLE栓塞组，患者术后一般发热3～7d，最高达38．1℃，术中有肝区憋胀，轻度疼痛，术后肝区疼痛较轻，均未使用止痛针剂。随访5个月，肿瘤平均缩小70％以上。2．用鱼肝油酸钠栓塞组．患者术后一般发热2～3d，最高者达38℃，术中即有肝区憋胀、巨痛，术后肝区疼痛剧烈，每个患者平均使用度冷丁200～300mg。随访5个月，肿瘤缩小72％以上。结论：笔者认为平阳霉素与鱼肝油酸钠对血管的硬化和肝血管瘤的治疗，疗效相当。但平阳霉素栓塞术后，临床反应较轻，痛苦小，患者更容易接受。     

锡渣生产锡酸钠中除锑的研究

利用生产硫酸亚锡、氯化亚锡、锡粉的含锡废料生产锡酸钠,生产成本低,但在这过程中需要除去的杂质也相对比较多。文章对除锑的工艺参数和条件进行了研究,重点探讨了除锑温度、除锑时间、除锑后溶液静置沉降时间等因素对锑效果的影响。结果表明,采用该工艺,Sb的脱除率为95.3%,产品质量符合Sn-42等级标准。