Iron removal from waterlogged wood: Extraction by electrophoresis and chemical treatments

Abstract

The presence of iron oxides (lepidocrocite, goethite) in archeological wood may result in a degradation of the wood matrix. Extraction of these iron oxides is largely dependent on their solubility. In this study, balsa wood samples were impregnated with iron oxides to test extraction treatments. Additionally, archeological wood samples were also examined to determine treatment efficiency. Electrophoresis and simple immersion treatments were performed using various chemical solutions: a neutral and a conductive substance (potassium nitrate), an acid (acetic acid), three alkaline chelating agents (tri-ammonium and tri-sodium citrate and sodium oxalate), three acidic and slightly acidic chelating agents (ethylenediaminetetraacetic acid (EDTA), citric acid, and oxalic acid), and a reductant (sodium dithionite). Potassium nitrate did not extract sufficient amounts of iron, irrespective of whether the treatment was conducted by electrophoresis or simple immersion; any observable dissolution was attributed to protonation because of the acidic pH around the anode (as low as 3). Dissolution in acetic acid did not extract iron with either treatment. Strong chelating agents improved extraction, and these compounds gave the best results for simple immersion, particularly EDTA. This chemical is well adapted for use on archeological objects because of its chemical properties (stability constant, speciation based on pH). The addition of sodium dithionite to the solution improved dissolution. Even though electrophoresis improved extraction (in particular for tri-ammonium citrate), none of the tested chelating chemicals were suitable for electrophoresis because of a significant increase in temperature as well as high anode corrosion. The presence of iron sulfide in the archeological wood limited the effectiveness of the tested chemicals. A pre-treatment in sodium persulfate was expanded to include oxidized iron sulfide in oxy/hydroxide iron, which improved the extraction rate.     

Conservation of chemically degraded waterlogged wood with sugars

The effectiveness of two non-reducing sugars, both analogues of sucrose, to conserve degraded waterlogged wood was examined. The two sugars examined are trehalose and sucralose, both stable and relatively unreactive. The ability of these sugars to conserve a series of degraded tongue depressors was measured by determining the anti-shrink efficiency of each at various concentrations and comparing them to sucrose. The findings of this study indicate that both sucralose and trehalose may be effective conservation treatments for waterlogged archaeological wood and that at moderate concentrations the performance of both is comparable to sucrose. However, sucralose has a lower solubility, and concentrations higher than 60% w/v were not examined, whereas concentrations of up to 100% w/v of trehalose were studied. At these higher concentrations trehalose performed as well, if not better than sucrose, although there were crystalline deposits on the wood surface at these higher concentrations. With modifications and careful control, both of these sugars may be suitable conservation alternatives to sucrose due to their long-term stability and resistance to hydrolysis.     

Post-treatment Study of Iron/Sulfur-containing Compounds in the Wreck of Lyon Saint-Georges 4 (Second Century ACE)

ABSTRACT

A pre-restoration diagnosis revealed a high amount of pyrite in the wood of the Lyon Saint-Georges 4 shipwreck (end of the second century). The occurrence of this phase is supposed to result from the microbiologically influenced corrosion of the iron fasteners. So, all the nails and metallic elements were removed from the remains before treatment and the wreck was consolidated by polyethylene glycol impregnation coupled to a specific desalination process. Treated and non-treated samples extracted from the wreck were studied in order to identify the iron/sulfur-containing compounds present in the wood before and after treatment and figure out its effect. Sample analyses relied on an original approach combining magnetic characterization methods and more common elemental and structural analysis methods. The results showed that the treatment was effective in removing soluble salts. However, a large amount of unstable iron sulfides remained inside the wood.     

Natural polymers as alternative consolidants for the preservation of waterlogged archaeological wood

In recent years, there has been increased interest in examining alternative polymers for the conservation of archaeological artefacts, particularly waterlogged timbers, providing better, renewable, greener alternatives to poly(ethylene glycol) (PEG). The degradation of PEG consolidants in the timbers of the sixteenth century warship Mary Rose has been examined and the rheological and thermal properties of PEG have been compared with its monomethyl and dimethyl ethers and several polysaccharide consolidants (chitosan, guar, and 2-hydroxyethyl cellulose) in order to evaluate their potential as alternative consolidants for the conservation of waterlogged wooden artefacts. Additionally, the effect of the polymers on the archaeological wood was characterised by thermogravimetric analysis and solid-state nuclear magnetic resonance spectroscopy. The results suggest that the future of conservation technologies lies with polysaccharide consolidant materials, which show enhanced compatibility with wooden artefacts with no detectable side effects while also being cheap, with extremely low toxicity, renewable, and sustainably resourced.     

Cellulose degradation in the Vasa: The role of acids and rust

Abstract

The oak timbers of the Swedish warship Vasa are deteriorating. High amounts of oxalic acid have been found along with a low pH and low molecular weight cellulose deep in the wood timbers. The iron-rich surface wood differs from the interior wood in that it displays higher pH and cellulose with higher molecular weight. The objective of this study was to determine why there is a difference in cellulose degradation, pH, and oxalic acid amount between the surface region and the interior of the Vasa timbers. Analysis of cellulose weight average molecular weight by size exclusion chromatography was performed, as well as quantification of oxalic acid and iron by high-performance anion exchange chromatography and atomic emission spectroscopy, respectively. It was found that a decrease in iron content coincides with an increase in oxalic acid concentration and a drop in pH at a certain depth from the wood surface. When iron-rich surface wood samples from the Vasa were mixed with an aqueous solution of oxalic acid, a fast increase of pH over time was observed. Neither interior wood poor in iron nor the fresh oak reference showed the same neutralizing effect during the time of measurement. This indicates that the presence of iron (rust) causes a neutralization of the wood, through the formation of iron(III) oxalato complexes, thus protecting the wood from oxalic acid hydrolysis. This effect was not observed to the same extent for other acids observed in Vasa wood (sulfuric, formic, glycolic, and acetic acids).     

Changing research trends in the field of archaeological wood at the Conservation Department,Faculty of Archaeology,Cairo University

Abstract

Since 1980, much research in the field of treatment and conservation of archaeological wood has been carried out at the Conservation Department, Faculty of Archaeology, Cairo University. Materials and methods used in conservation have been changing gradually over the years worldwide. It was necessary to study critically previous masters and doctoral dissertations on Egyptian archaeological and historic wood, all written in Arabic. This review of them includes a brief history of the Conservation Department at Cairo University and five main focal points of past research: types of wood used throughout Egyptian history, assessment of wood decay, wood properties and composition, treatment and conservation of decorated wood, and the evaluation of chemicals and polymers used in the treatment of archaeological wood and composite objects containing wood.     

WTO环境下高校图书馆信息服务的探索

本文分析了我国加入WTO后,高校图书馆信息服务面临的机遇和挑战,并对WTO环境下的高校图书馆信息服务进行了探讨。文章主要从高校图书馆信息服务的市场定位、加强法律法规意识、积极采用新技术新设备、加快"虚拟馆藏"建设、针对用户需求开展多元化信息服务等五方面阐述了WTO环境下高校图书馆信息服务的对策。     

2000-2016年国外突发事件的应急信息管理研究进展

[目的/意义]突发事件的应急信息管理是当前国内外都十分关注的一个跨学科多领域的研究主题,总结国外相关研究文献的研究内容、视角与方法,为国内相关领域的研究提供参考借鉴。[方法/过程]采用文献计量法与内容分析法相结合的方式,按研究内容主题和重点领域对国外突发事件的应急信息管理研究文献进行归纳总结。[结果/结论]从应急信息基本内涵、应急信息沟通、应急信息管理系统和应急信息管理重点领域4个方面着重分析国外突发事件的应急信息管理研究现状,对国内研究的启示包括：应进一步加强跨学科多领域深入研究,加强案例和实证研究,拓展应急信息管理研究内容。     

《中图法》第五版地区类目修订探讨

针对《中国图书馆分类法》第五版修订中涉及地区类目的修订措施,从类目设置、修改注释、增加仿分复分、明确类目含义、地区名称规范、标记符号的使用等几个方面探讨成功与不足,并提出改进建议。     

《中图法》第四版的"中国法律"标引探讨

文章从《中图法》第四版的“中国法律”分类标引加“000”例证入手,通过分析研究否定了某些偏颇观点,并从《中图法》的整体情况综合考虑,认为应当将中国法律的总论(综合性法规)与分论(专论)的复分区分开,修订某些类目注释的不恰当。文中还采用较典型的实例进行分析、说明、印证,虽然某些文献的标引结果呈现“0000”连续现象,但是实际标引加“0”还只限于“00”。     

《纽约时报》和《泰晤士报》中的上海形象研究(2010-2017)

本文以框架理论为方法,通过对2010-2017年《纽约时报》和《泰晤士报》上海新闻报道的话语和框架进行分析发现,上海形象塑造中所凸显的要素处于一种矛盾复杂的境地:上海既前景广阔又充满考验,在政府调控与各种不成熟不完善的市场环境中迅速崛起;上海作为一个现代开放的国际重量级文化中心,又存在市民群体规则意识薄弱,城市公共安全管理隐患不断的媒体形象。文章还探讨样本框架建构特征表现为政治化倾向的归因定势和完整性叙述缺乏。     

RISE-DE评估模型在大学研究数据管理(RDM)中的应用及对比分析——以波茨坦大学为例

大学研究数据管理作为开放科学进程的重要组成部分,越来越受到各国政府、科学组织、研究机构的重视。通过对德国波茨坦大学RISE-DE模型在制定RDM面向利益相关者参与的结构化战略流程中的应用进行分析,对基于CMM的美国雪城大学RDM模型,借鉴康奈尔模型的格拉斯哥大学CARDIO模型,以及基于DCC的RISE模型的德国RISE-DE模型进行对比研究,梳理三种能力成熟度模型的差异和特点,为我国高校开展研究数据管理服务工作提供借鉴。     

信息图表在我国报纸新闻传播中的应用研究——以1999-2008年神舟飞船报道为例

通过对1999年到2008年的6家报纸神舟飞船报道中信息图表的量化研究,揭示在重大新闻报道中信息图表的使用量、使用方式、制作来源、类型、所在版位等的现状和发展趋势,并对其存在问题和传播优势进行探讨。     

中文学术期刊论文的引文模式研究——以2006-2008年图书情报领域期刊论文为例

[目的/意义]探索中文学术期刊论文的引文模式及时间窗口的选择对引文模式的影响，建立引文模式的分析框架。[方法/过程]以2006-2008年出版的图书情报领域期刊论文作为研究对象，采用两步聚类法对单篇论文在7年内的绝对被引量与相对被引量进行聚类分析，研究论文主要特征因子与引文模式的相关性。[结果/结论]在绝对被引量视角下，期刊论文均表现为先上升后下降的经典引文模式；在相对下载量视角下，期刊论文共有6种引文模式，其中3种可以归纳为经典引文模式，另外3种分别为"类睡美人型"、正偏型和马拉松型。相对被引量视角下，首年被引量与总被引量呈现了中等甚至较强的相关性，并且平均被引量越高，相关性越强，绝对被引量视角下的结果正好相反。结果表明，期刊论文的初始被引量与总被引量的相关性高低主要取决于引文曲线的峰度而非总被引量的大小。     

公共图书馆创新服务案例研究——基于两届全国公共图书馆创新创意征集推广活动案例的比较与分析(2018-2019)

文章比较分析了2018-2019年两届全国公共图书馆创新创意征集推广活动的268个获奖案例,并对近年来公共图书馆创造性转化及创新性发展的经验与成效进行了系统总结,认为公共图书馆创新服务工作应善用跨界思维的模式,通过技术的不断革新,优化读者阅读体验,同时对特殊群体的文化缺失提供对位关怀,并顺应媒介融合,注重创新成果的营销推广。