聚醋酸乙烯酯乳液的表征、性能及其在彩绘类文物保护中的应用

聚醋酸乙烯酯(PVAc)乳液是常见的彩绘类文物保护材料。采用激光粒度仪、热重/差热分析、红外光谱、X-射线衍射、扫描电镜、透射电镜等表征了PVAc乳液的粒径以及胶膜的热稳定性、结构和形貌;采用粘度计、表面张力仪、pH计、电导率仪等研究了乳液浓度与其粘度、表面张力、pH、电导率的关系;通过冻融、室温-高温放置、离心分离研究了乳液的稳定性;同时用PVAc乳液对模拟起甲和酥碱的壁画进行了修复。结果表明,PVAc乳液粒径呈双峰分布,小粒子的平均粒径为380 nm,大粒子的平均粒径为5.85μm;乳液胶膜为非结晶物质,胶膜热重的最终质量残留为1.54%,335℃出现放热峰。PVAc乳液的电导率随浓度的增大而增大,pH随浓度的增大而下降;相同温度下表面张力随浓度的增大而基本呈现低浓度下降,高浓度上升的趋势。相同浓度下,表面张力随温度升高而无显著变化,表明PVAc乳液的表面张力受温度变化影响不大。相同温度下,乳液粘度随浓度的增大而增大;相同浓度下,乳液的粘度随温度的升高而降低。冻融、离心分离和不同温度下静置发现,该乳液出现分层。用该乳液对模拟起甲和酥碱壁画修复后,再分别老化20个循环和12个循环,发现颜料层再次空鼓、起甲。综合分析,说明实验中所使用的该种PVAc稳定性和抗老化能力较弱,在修复彩绘类文物中应慎重选择PVAc的种类,综合考虑PVAc的使用浓度、环境因素对其性能的影响,以达到最佳使用效果。     

Geochemistry and origin of natural gases dissolved in brines from gas fields in southwest Japan

Previous geochemical studies indicated that most natural gases dissolved in brines in Japan are of microbial origin, consisting of methane produced via carbonate reduction. However, some of those from gas fields in southwest Japan contain methane relatively enriched in ¹³C, whose origin remains to be clarified. To address this issue, chemical and isotopic analyses were performed on natural gases and brines from the gas fields in Miyazaki and Shizuoka prefectures, southwest Japan. Methane isotopic signatures (δ¹³C ≈ ?68‰ to ?34‰ VPDB; δ²H ≈ ?183‰ to ?149‰ VSMOW) suggest that these gases are of microbial (formed via carbonate reduction) or of mixed microbial and thermogenic origin. The relatively high δ²H‐CH₄ values and their relationship with the δ²H‐H₂O values argue against the possibility of their formation via acetate fermentation. The δ¹³C‐CO₂ values (≈?5‰), together with the slope of the correlation between δ²H‐CH₄ and δ¹³C‐CH₄ (Δδ²H‐CH₄/Δδ¹³C‐CH₄ ≈ 1), contradict the possibility of their formation via carbonate reduction followed by partial oxidation by methanotrophs. The ³He/⁴He ratios of the gases from Miyazaki (≈0.11–1.3 Ra) and their low correlation with δ¹³C‐CH₄ values do not support an abiogenic origin. It is inferred therefore that the high δ¹³C‐CH₄ values of natural gases dissolved in brines from gas fields in southwest Japan are indications of the contribution of thermogenic hydrocarbons, although whether abiogenic hydrocarbons contribute significantly to the gases from Shizuoka requires further investigation. This study has clarified that, for the future exploration of natural gases in southwest Japan, we should adopt the strategies for conventional thermogenic gas accumulations, such as checking the content, type and maturity of organic matter in the underlying sedimentary rocks.     

Synthesis by microbes or chemists? Pharmaceutical research and manufacturing in the antibiotic era

This article presents a case study of the rise of Pfizer as a leading pharmaceutical company, with a focus on changing relationships between manufacturing technology and R&D between the mid 1940s and the mid 1960s. Pfizer first moved into pharmaceuticals through participation in the US government's penicillin effort during World War II. The company had expertise in deep tank, biological fermentation for the production of chemicals that it adapted to the manufacture of penicillin. Having greatly expanded its biological manufacturing capacity to meet state needs, Pfizer adopted an R&D program to find new microbial antibiotics suited to its manufacturing technology after the war ended. Pfizer's successes in this antibiotic era established the firm as a major pharmaceutical company. In looking to larger commercial markets for drugs, Pfizer, like its competitors, pursued medicines for chronic diseases rather than acute infections. For this pursuit, in the 1950s and 1960s, Pfizer transformed itself into a chemistry‐orientated pharmaceutical firm by reorienting its R&D toward chemistry. This led to a growing divergence between R&D and manufacturing and the eventual replacement of biological manufacturing with chemical manufacturing. The article explores the changing trajectories of R&D and manufacturing at Pfizer, their shifting positions within the firm, and the consequences of these changes and shifts for the firm's strategy and organization.     

在硫代硫酸钠—醋酸铅双组分体系中黄铜器表面着色的动力学研究

通过调整流代硫酸钠一醋酸铅双组分试液的不同浓度比以及控制着色温度、试液酸度和着色时间,确定黄铜试样表面着以不同颜色的条件。用x射线衍射方法测定不同颜色表面膜的成分,并对膜形成的动力学进行了探讨．为研究黄铜着色提供了一种新的方法。     

几种罕见的黄铜钱币锈蚀产物的识别与形成原因探析

我国从明中期开始使用黄铜钱币,一直到清末。过去,对古代铸币的科学研究主要集中于合金成分分析和铸造工艺两方面,对锈蚀产物和锈蚀机理的研究主要针对青铜铸币。黄铜的合金元素中较青铜多锌元素,其腐蚀产物与腐蚀行为较青铜有一定的差别,也较青铜更为复杂,然而现有的文献关于此方面的研究匮乏,特别是对于大气保存环境下黄铜钱币的锈蚀产物及锈蚀成因的研究基本空白。本研究通过多种分析手段包括X射线荧光分析仪(XRF)、扫描电镜能谱仪(SEM-EDS)和显微激光拉曼光谱仪(Raman)对国家博物馆馆藏一批传世明清各时期的黄铜钱币合金组成,不同颜色的锈蚀产物等开展科学分析。研究结果表明,嘉靖、隆庆和万历年的黄铜铸币,为Cu+Sn+Pb+Zn四元合金,平均含量Cu 66.4%,Sn 6.8%,Pb 10.4%,Zn 15.6%,并含有微量Fe,不含As。泰昌、天启和崇祯年间及清代各时期的黄铜铸币,主要为Cu+Pb+Zn三元合金,并含有微量Fe、As和Sn。这批黄铜锈蚀产物与常见的青铜锈蚀产物不同,最典型的是钱币表面蓝绿色和白色锈蚀物,经Raman和SEM-EDS分析并结合相关文献初步确认蓝绿色锈蚀物为一种含铜、钠...