氢氘交换用于古代皮革胶原蛋白微观结构的研究

皮革文物由动物皮制作而成,是人类在认识和改造自然过程中留下的宝贵财富,是研究古代社会历史的珍贵实物史料。皮革作为一种天然有机高分子材料,其主要组成成分胶原蛋白易受保存环境影响发生变性劣化,研究胶原蛋白的微观结构对于了解古代皮革的劣化具有非常重要的意义。氢氘交换技术(HDX)基于蛋白质中不稳定的氢原子会与氘原子发生交换的原理常被用于蛋白质结构研究,但其用于古代皮革胶原蛋白的结构研究却鲜见报道。本研究采用HDX结合傅里叶变换红外光谱技术(FTIR),对现代皮革、人工老化皮革和古代皮革胶原蛋白的三股螺旋结构进行了分析和比较研究,通过特征吸收峰的位置和氘代率来表征胶原蛋白微观结构的变化。研究结果表明现代皮革胶原蛋白的三股螺旋结构保存完整,氘原子难以进入其中与主链氨基氢原子发生交换反应,氘代率为32.09%。而人工老化皮革和古代皮革在劣化过程中胶原蛋白主链酰胺氢的溶剂可及性以及其参与形成的氢键发生了变化,维系三螺旋结构稳定的氢键断裂,三股螺旋结构发生一定程度解体,位于螺旋结构中心的甘氨酸暴露出来,增大了骨架酰胺氢的溶剂可及性,结构变得松散不稳定,加快了氢氘交换速率,更容易发生氢氘交换反应。三个古代皮革样品中Old3的氘代率最低,氘代率为65.87%,其三股螺旋结构被破坏程度最小,劣化程度也最轻。与之前已报道的氢氘交换研究蛋白质结构的文献相比,在以下方面做出拓展:一是通过分析胶原蛋白特征结构,指出主链氨基氢尤其是甘氨酸的酰胺氢是与氘原子发生交换的主要对象。二是根据氢氘交换后相应基团质量数发生变化会引起伸缩振动频率的变化这一特点,选择傅里叶变换红外光谱中胶原蛋白的酰胺A带来作为氢氘交换反应的表征工具,通过特征峰的位置和氘代率来量化氢氘交换程度。本研究将氢氘交换技术与傅里叶变换红外光谱技术相结合,引入到皮革文物胶原蛋白结构的研究中,有助于深刻理解皮革文物劣化机理,为胶原蛋白微观结构的研究和皮革文物劣化程度分析提供了一种新的方法和研究思路。     

盖蒂保护研究所的亚洲漆快速识别方法

正漆长期以来广泛地用于装饰和建筑元素,以漆为黏合剂或表面保护剂的古代艺术品也成为一类分布广泛且具有地域特征的珍贵文化遗产。然而,由于漆本身的化学结构复杂,而且有些艺术家擅长在漆中添加其他材料调节所需效果,造成不同黏合剂之间检测分析时的相互干扰,使漆的分析识别极具挑战性。热裂解气相色谱-质谱(Py-GC/MS)联用技术是一种非常灵敏的、适合于漆检测的有效分析技术。由于Py-GC/MS不需要任何富集等复杂的前处理程序,对于只能采取极少量样品的     

热裂解-气相色谱/质谱在文化遗产研究中的应用进展

色谱和质谱联用技术是有机物常用的一种分析方法,在文物保护与考古残留物研究等方面的应用已有几十年的发展。色谱与质谱联用分析样品时,需要对样品进行水解提取、衍生化等前处理,这个过程较繁琐,且耗时长,另外在样品处理过程中还有样品流失的情况发生。因此,现在一般采用热裂解-气相色谱/质谱联用技术(pyrolysis-gas chromatography/mass spectrometry,Py-GC/MS)来分析有机质样品。Py-GC/MS在分析样品时有如下优势:无需对样品进行前处理,样品可直接进行热裂解分析,操作比较简单;灵敏度高,能实现多组分混合有机样品识别;需要样品量很少,可满足文物样品微损分析检测的要求。因此,该方法在文化遗产保护和考古有机残留物识别鉴定中发挥了重要的作用。     

故宫太和殿护板灰有机组分的红外光谱及热裂解-气相色谱/质谱分析

为研究太和殿护板灰中所含有机组分,通过傅里叶变换红外光谱(FTIR)及热裂解-气相色谱/质谱联用仪(Py-GC/MS)对太和殿上层护板灰、太和殿上层西南角护板灰进行分析检测。FTIR分析结果表明两个护板灰样品含有碳酸盐及油脂或虫胶漆类有机物,Py-GC/MS分析进一步确定两个样品所含有机物是植物油,且可能是生桐油与十字花科植物油脂的混合物;此外,在两个样品中检测到的雪松醇应该是太和殿所用杉木望板的挥发组分,而太和殿上层护板灰中则可能含有淀粉。研究结果有助于科学还原太和殿古建护板灰的传统制作方法。     

纸质文物的热裂解气相色谱-质谱应用研究

对纸质文物的科学认知是保护这类珍贵文化遗产的关键。本研究将热裂解气相色谱-质谱(Py-GC/MS)技术应用到中国传统的四类典型手工纸(竹纸、麻纸、桑皮纸和构皮纸)的分析中,结果表明竹纸中苯酚类物质含量较高,桑皮纸和构皮纸中含有大分子三萜类特征物(如β-香树脂醇、α-香树脂醇和豆甾-3,5-二烯等物质),而麻纸中则无此类特征物——利用这些特征化合物可以区分竹纸、麻纸和桑皮/构皮纸。将这一成果应用到一副清代蜡笺纸对联的分析中：确定了该书法用纸为皮纸(桑皮纸或构皮纸);检测出长链脂肪酸和醇类物质,表明蜡笺纸的制作使用了蜂蜡;检测出吡咯及其衍生物,表明该书法蜡笺纸装裱时所用的胶结材料为动物胶;另外检测到了生物碱类物质,表明该蜡笺纸使用了植物染料。综合以上研究表明,Py-GC/MS方法不仅能够确定中国传统纸质文物的纤维来源,同时可以确定纸质文物上蜡、胶结物及染料等信息;结合传统的赫兹伯格(Herzberg)染色法,进一步确定了皮纸的具体种类。蜡笺纸文物材料信息的检测识别可为文物保护与修复工作提供科学依据,此研究方法为纸质文物的科学认知提供新思路。     

南唐二陵壁画历史保护修复材料的分析

为了确定南唐二陵壁画已有保护修复材料的种类,使用多光谱摄影技术分别对钦陵和顺陵壁画保护修复材料的分布区域进行探查,在紫外荧光图像中确定了保护修复材料的位置,通过红外光谱和热裂解-气质联用技术对材料进行了成分分析。结果表明二陵壁画所使用的保护修复材料主要为苯乙烯-甲基丙烯酸甲酯共聚物和聚醋酸乙烯酯,还发现少量多糖类物质,为调和地仗石灰层所使用的糯米汁。该研究表明通过多光谱摄影技术提供线索,使用红外光谱、热裂解-气质联用确定成分是一种可靠的墓葬壁画保护修复材料分析方法体系,为墓葬壁画保护修复材料的鉴别提供借鉴,也为保护修复材料在墓葬壁画中的应用效果评价和劣化机理研究提供参考。     

故宫东华门城楼天花颜料胶结材料的科学研究

为研究故宫东华门城楼井口天花所用颜料胶结材料,通过热裂解-气相色谱/质谱联用仪(Py-GC/MS)、红外衰减全反射(ATR)面扫描对东华门绢本、纸本天花绿色颜料层分别进行分析检测。PyGC/MS分析表明绢本天花绿色颜料层所用胶结材料应为动物胶,且天花上有油脂类污染物;红外ATR面扫描分析确定纸本天花绿色颜料层所用胶结材料为蛋白质类材料,且可能为动物胶。研究结果有助于故宫东华门城楼井口天花制作工艺的研究及保护方案的制订。     

现代仪器分析技术在漆膜研究中应用现状

运用现代仪器分析,通过对古代漆膜组成和结构的研究,揭示古代漆器的髹漆工艺特点,为漆器文物鉴定、保护、修复与复制提供依据。研究古代漆膜组成物质在劣化过程的变化情况,是漆膜保护材料和技术研究的重要依据。文章介绍了现代仪器分析在古代漆膜研究中的应用情况。     

“相关元素法则”在古代丝织品媒染剂研究中的应用

古代常用的明矾、青矾、单宁酸、胆矾、铬明矾和铁浆做媒染剂,媒染剂中的金属离子对古代丝织品的劣化有促进作用。因此,分析古丝绸中的媒染剂成分,有助于了解古代丝织品劣化的机理,为有效保护提供科学依据。本文提出了“相关元素法则”概念,并将此法则应用于古代丝织品媒染剂研究。     

利用FT-IR、Py-GC/MS和THM-Py-GC/MS微损分析技术探索油画文物复杂的有机基质组成

近现代油画有机基质组分复杂、难辨,其分析鉴定是当今文物保护科技研究的难点之一。利用微损分析技术研究油画文物复杂的基质结构、材料和技法,可以阐明油画特定层的性质和状况,对于专业保护人员制定修复决策至关重要——这对选择正确修复技术非常有用,关系到修复后油画的安全状态,因此已成为许多研究者关注的焦点。本研究利用傅里叶变换红外光谱(FT-IR)、热裂解气相色谱-质谱(Py-GC/MS)和热辅助水解甲基化-裂解气相色谱-质谱(THM-Py-GC/MS)等微损分析技术对一幅中国国家博物馆藏油画《德涅泊尔河的秋天》进行科技分析。研究发现,综合运用这些微损分析技术可以有效识别油画用的胶结介质和其中添加剂的种类,最大限度、准确、完整地提取样品中所蕴含的信息。结果表明,该油画的有机胶结材料为聚乙烯醋酸酯类材料和亚麻籽油,同时聚乙烯醋酸酯类材料中使用了邻苯二甲酸二丁酯作为增塑剂。裂解产物中不含光油树脂类成分,说明画作下部的光亮层并非作者有意上的光油层。此外,油画部分区域还添加了蜂蜡作为改性材料,起到增加颜料稠度、可塑性和减弱光泽的作用。     

山东沂源出土战国皮革文物的材质鉴别

山东沂源发掘的一座战国晚期墓葬,保存完好,随葬品丰厚。其中有皮革制品,这在北方考古发掘中十分罕见。对出土皮革文物的研究,为研究北方地区战国时期的皮革制品提供了重要的实物依据。因此,本研究利用衰减全反射—傅里叶变换红外光谱(ATR-FTIR)和扫描电子显微镜(SEM)对战国皮革文物材质进行了分析鉴别,初步判定沂源出土战国皮囊为羊皮革制品。研究结果对皮革文物材质的科学鉴别提供了借鉴,为科学、有效保护奠定了基础。     

Looking for Ancient Fish Products Through Invisible Biomolecular Residues in the Roman Production Vats from the Atlantic Coast

As organic materials, fish and its derivative products are perishable and break down rapidly and ultimately disappear. Unless they include bones or scales, the only means of identifying them in the archaeological record is through the identification of the chemical constituents that are left behind after decomposition. Fish flesh mainly consists of proteins and lipids. Since these molecules are unstable they degrade irreversibly after death or discard, losing a significant part of the original chemical elements, consequently hampering or complicating their identification. In this paper, two main types of fish products are considered: raw, salted or cooked fish, and fermented fish-based products. In the first case, the degradation of the native markers results from chemical post-depositional degradation, and eventually thermal degradation during cooking. In the second case, the biochemical processes involve bacteria that cause the rapid decomposition of fish as part of the process of forming fish sauces, such as Roman garum. To detect and identify fish products we combined experimental archaeology and organic analyses. The identification of the degradation products of cholesterol appeared to provide a strong indicator for detecting the presence of fish sauces. Analysis of samples taken from fish-salting vats located along the Atlantic coast (Marsa, Baelo Claudia, Troia, Kerlaz, and Etel) with samples taken from actual experimental garum sauces made from mackerel (Scomber scombrus), sardines (Sardina pilchardus), and/or oysters (Ostreidae), revealed the presence of common markers of fermented fish-based products. The application of the analytical methodology described here to structures involved in ancient fish sauce manufacture and storage has enabled investigation of the production of the sauces by searching directly for the fish markers on the inner sides of the containers. For the first time the addition of molluscs and fruits in the fish product has been identified as part of the process of manufacturing garum.     

Evaluation of the rate of wood degradation at the Iron Age archaeological site of Biskupin,Poland

A study was made of the degradation of archaeological Scots pine (Pinus sylvestris L.) at the Iron Age archaeological site of Biskupin, Poland. Wood degradation was evaluated after 10 years of deposition of samples in different burial conditions (mineral soil, peat and water) and at different depths (25, 50 and 100 cm) at the location of the original archaeological wood from the Lusatian culture settlement. Changes in the wood samples were assessed on the basis of selected physical (maximum water content, basic density and porosity) and chemical (chemical composition, structure of cellulose and lignin) properties. The observed degradative changes were different for samples deposited in different locations of the archaeological site and at different depths. They relate mainly to carbohydrates—both cellulose and hemicelluloses—although the structure of lignin also underwent changes. The experiment using wood that had been degraded to a similar degree to the Biskupin wood enabled identification of the actual danger of degradation of the latter. It was found that the remains of the wooden structure of the Biskupin settlement are degrading, despite the favourable physicochemical conditions prevailing at the site, and it is necessary to take measures to prevent its further decomposition.     

THE SEARCH FOR THE ORIGIN OF BITUMEN EXCAVATED FROM ARCHAEOLOGICAL SITES IN THE NORTHERNMOST ISLAND IN JAPAN BY MEANS OF STATISTICAL ANALYSIS OF FI–MS DATA*

The origin of bitumen excavated from archaeological sites in Hokkaido, the northernmost island in Japan, was sought by means of field‐ionization mass spectrometry (FI–MS) and gas chromatography – mass spectrometry (GC–MS) of the hydrocarbon components. The field‐ionization mass spectra were decomposed by Z‐numbers into several components, where the Z‐number refers to z in the formula C _n H _2n+z . This is equivalent to the deficit number of H atoms, when compared to the corresponding saturated hydrocarbon, which is related to the number of saturated hydrocarbon rings in alkanes. By use of the spectral intensities of the seven alkane components in each sample, multiple discriminant analysis was employed for the data of raw bitumen samples and excavated samples from archaeological sites. Based on this method and the gas chromatogram type, the following bitumen trade in the prehistoric age of Japan was elucidated: bitumen from Niigata, one of the main sources on the main island of Japan, spread to the north in 2000 bc , probably via the coastal zone, and reached a small island near the north end of Hokkaido. Bitumen from Sakhalin reached the central lowland in Hokkaido, but it went no further. Bitumen from Akita, another main source on the main island, spread over northern Honshu much earlier and reached the Oshima peninsula, the southwestern part of Hokkaido. The Akita bitumen scattered into the central lowland after the Niigata and Sakhalin bitumen. This area is believed to be the place where people from the south and the north met in those periods.     

Assessing the distribution of African Palaeolithic sites: a predictive model of collagen degradation

In order to assess the distribution of African Palaeolithic sites and hominin remains, we need an understanding of the factors that may affect the preservation of archaeological material in the fossil record. One of the main factors that is thought to affect seriously the global distribution of fossil remains is taphonomy, but it would seem that taphonomic processes may themselves be overprinted by collagen degradation.The rate of collagen loss is highly temperature dependent, and it has been shown that bone is more likely to be preserved in areas of lower temperature and so lower collagen loss. Hence, it would be expected that fossil fauna remains would be distributed in areas of low collagen loss, i.e. low temperature. Conversely, lithics will not be subject to a temperature bias in their preservation. We have tested this hypothesis through the use of archaeological material.Our results show that the distributions of both lithic and faunal assemblages are non-random across the African continent, with all archaeological sites being found in areas of relatively low collagen degradation. This implies that bone collagen degradation is not the only factor affecting the distribution of African Palaeolithic sites and hominin remains. We suggest that the site distribution is not a reflection of bias in excavation history, but is a real phenomenon reflecting hominin habitat choice.     

Fish bone chemistry and ultrastructure: implications for taphonomy and stable isotope analysis

This paper reviews the ultrastructure and chemistry of fish bone, with an emphasis on zooarchaeology and stable isotope analysis. On the basis of the chemical composition of the collagen and the relationships between the collagen and mineral phases, fish bone is more susceptible to biotic and abiotic degradation than mammalian bone and is therefore less likely to be recovered in archaeological deposits. The amino acid composition of fish bone differs from that of mammals, most notably with respect to hydroxyproline content. The C:N ratio of fish collagen is, however, very similar and slightly lower than mammalian collagen, and thus the traditional range of acceptable C:N ratios for archaeological bone collagen (2.9–3.6) should not be shifted or extended for fish on the basis of the amino acid composition of collagen. An extensive survey of published archaeological bone collagen C:N ratios demonstrates that fish collagen from archaeological contexts tends to have significantly higher C:N ratios than mammalian collagen. The elevated C:N ratios in fish bone collagen may be the result of abiotic degradation processes that occur within the bone after death, the presence of exogenous humic contaminants, or endogenous lipid contaminants.     

Preservation of Fossil Seeds From a 10th Century AD Cess Pit at Coppergate,York

Fossilization processes were investigated in terrestrial archaeological deposits, focusing on the preservation of sub-fossil seeds from a 10th century cess pit at Coppergate in York. Flash pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS) revealed that the bulk of the assemblage comprises well-preserved organic remains, exemplified by blackberry (Rubus fruticosus) endocarps which retain a near-pristine ligno-cellulose composition. Crab apple (Malus sylvestris) pips are unique in combining an organic seed coat with an embryo which has been phosphatized. Endosperm tissue, nutrient spheres in the cotyledons and, in one specimen, the cotyledon cell walls are replicated in calcium phosphate. Casts of the sclerotic tests cells were also observed in one specimen. The crab apple seed coats have an unusual composition, interpreted as a tannin-cellulose complex. Precipitation of early diagenetic minerals among these organically preserved fossils appears to be restricted to seeds with permeable coats through which ions were transported from pore waters.     

Microstructural,chemical and isotopic evidence for the origin of late neolithic leather recovered from an ice field in the Swiss Alps

Archaeological leather samples recovered from the ice field at the Schnidejoch Pass (altitude 2756 m amsl) in the western Swiss Alps were studied using optical, chemical molecular and isotopic (δ¹³C and δ¹⁵N of the bulk leather, and compound-specific δ¹³C analyses of the organic-solvent extracted fatty acids) methods to obtain insight into the origin of the leather and ancient tanning procedures. For comparison, leathers from modern native animals in alpine environment (red deer, goat, sheep, chamois, and calf/cow) were analyzed using the same approach. Optical and electron microscopically comparisons of Schnidejoch and modern leathers showed that the gross structure (pattern of collagen fibrils and intra-fibrils material) of archaeological leather had survived essentially intact for five millennia. The SEM studies of the hairs from the most important archaeological find, a Neolithic leather legging, show a wave structure of the hair cuticle, which is a diagnostic feature for goatskins. The variations of the bulk δ¹³C and δ¹⁵N values, and δ¹³C values of the main fatty acids are within the range expected for pre-industrial temperate C₃ environment. The archaeological leather samples contain a mixture of indigenous (from the animal) and exogenous plant/animal lipids. An important amount of waxy n-alkanes, n-alkan-1-ols and phytosterols (β-sitosterol, sitostanol) in all samples, and abundant biomarker of conifers (nonacosan-10-ol) in the legging leathers clearly indicate that the Neolithic people were active in a subalpine coniferous forest, and that they used an aqueous extract of diverse plant material for tanning leather.     

The Impact of Climate Change on an Archaeological Site in the Arctic

Climate change may accelerate the degradation of archaeological sites in the Arctic and lead to a loss of important historical information. This study assesses the current preservation conditions and the processes controlling the physical and chemical stability of the Qajaa kitchen midden in western Greenland. Currently, the site is well protected by low ground temperatures, permafrost and a high water/ice content, keeping the deposits anoxic. Based on 5 years of monitoring data, degradation experiments and model simulation, our results suggest that the combined effects of permafrost thaw, thermal and hydrological erosion and oxygen exposure may lead to substantial loss of archaeological evidence before the end of the 21st century.