The Use of Optical Coherence Tomography for Monitoring the Subsurface Morphologies of Archaic Jades

We demonstrate the use of the Optical Coherence Tomography (OCT) technique for non‐invasive scanning of the subsurface morphologies of jade objects. The two‐dimensional tomography images show the refractive index or dielectric constant variations in the samples, reflecting their structures. Three samples of archaic jade objects from the Qijia and Liangzhu cultures in China are scanned in order to understand the subsurface morphologies of the naturally whitened jades. Also, two jade objects with artificial treatments (burning) are scanned and compared with the original materials in subsurface structures. In the original objects, the jade materials can generally be quite transparent, such that the backscattering intensity is weak, although the large‐scale (tens of microns or larger) subsurface morphology can be clearly observed. After burning, small‐scale (smaller than a few microns) structures are formed and the backscattering intensity is enhanced. In this situation, the large‐scale structures may be preserved or even newly generated. On the other hand, in an archaic object with natural whitening, small‐scale structures are also formed. Hence, the deeper distributions of significant backscattering intensity are observed, when compared with the unwhitened objects. Nevertheless, the large‐scale features diminish during the whitening process. With OCT scanning, such differences in subsurface morphology can provide us a valuable reference for authenticating archaic jade objects.     

Egyptian Blue cakes from the Ayanis fortress (Eastern Anatolia,Turkey): micro-chemical and -structural investigations for the identification of manufacturing process and provenance

The microstructure and chemical composition of blue cakes, found during the archaeological excavation of the Ayanis fortress (Eastern Anatolia, Turkey), have been investigated by means of scanning electron microscopy combined with energy dispersive spectrometry (SEM–EDS), X-ray diffraction (XRD), micro-Raman (μ-Raman) and optical microscopy (OM) techniques. The analysis of the Ayanis cakes has shown the presence of Egyptian blue (i.e. CuCaOSi₄O₁₀, cuprorivaite), as the major component, intermixed with minor amount of other phases such as partially reacted quartz grains, an adherent glass phase and copper oxides. Since the finding of Egyptian Blue in Turkey has been never reported so far, great attention has been paid to its characterisation. The micro-chemical and micro-structural investigations of the Ayanis cakes have allowed a further insight into the manufacturing process and into the sources of the starting materials. The results of the characterisation have revealed some significant differences with respect to Egyptian blue cakes found in Egypt and Mesopotamia, as for instance the absence of tin excluded the use of bronze scraps or filings in their preparation differently from those produced in Egypt and Mesopotamia. Furthermore, some peculiarities of Egyptian blue found in Ayanis, as the detection of zinc in the cakes, allow to put forward the hypothesis of a local production considering that a large part of the bronze artefacts found at the Ayanis fortress is characterised by the presence of zinc as minor alloying element.     

高光谱成像技术在中国古代书画分析中的应用研究综述

中国古代书画，因其年代久远，递藏情况复杂，多数屡经裁切割补、修复重装，故而有很多历史信息或被叠摞或被遮蔽，导致今人不能以肉眼直接观察而获得，而纸绢接补，墨迹、颜料、印鉴的残损也为书画研究者带来诸多悬而未决的问题。近年来，高光谱技术作为一种非侵入式的光谱成像技术，已逐步应用于各类彩绘文物中，该技术可为中国古代书画研究和保护提供更丰富的信息。本工作以文献调研为基础，简要介绍了高光谱成像的原理及技术特点，对高光谱技术在中国古代书画研究的实践进行总结，梳理了国内外研究者利用高光谱技术在书画、档案及相关彩绘文物的增强显示、物质识别、虚拟修复方面的应用案例，以期为相关研究者提供参考借鉴。     

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。     

Investigating the likelihood of a reservoir offset in the radiocarbon record for ancient Egypt

Some radiocarbon dates for ancient Egypt have been significantly offset from the established historical chronology (see Bonani et al., 2001). In this paper, short-lived plant species collected in Egypt between 1700 and 1900 AD were used to investigate the possibility that the radiocarbon record had been influenced by reservoir effects. AMS radiocarbon measurements were made on 66 known-age samples, resulting in an average offset from expected values of 19 years. The implications of this minor discrepancy on the likelihood of a reservoir process are discussed, and the agreement of the data with recent models of radiocarbon seasonality is also considered.     

New data on relevant ancient Egyptian wooden artifacts: Identification of wooden species and study of the state of conservation with multidisciplinary analyses

Wood species identification and characterization of its weathering processes are crucial steps in the scientific approach of conservation of wooden cultural heritage. Many precious wooden objects of ancient Egypt are largely present in museums, nevertheless relatively little information is available concerning the nature of timber used and on their status of conservation. To address this gap, the wooden species of three relevant archaeological wood objects (statue, box, and coffin) arising from different Egyptian archaeological sites dated from the Old Kingdom (2,686–2,181 BC) to New Kingdom (1,550–1,069 BC) were deeply studied. Five hardwood and softwood species were identified belonging to Tamarix mannifera, T. gennessarensis, Ficus sycomorus, Vachellia nilotica, and Cedrus sp. Such data confirmed the recurrence of Vachellia and Tamarix among the most common timbers found in ancient Egypt. Scanning electron microscope, Fourier transform spectroscopy, and synchrotron x-ray radiation diffraction were conducted to evaluate the archaeological wood deterioration. The formation of microcracks, biological degradation patterns (fungal colonization), or chemical characterization (accumulation of salts on and in-between wooden cells) were detected. SEM micrographs showed the presence of fungal hyphae and conidial spores on the wooden cells. Significant changes in the chemical wood composition and decrease in the crystallinity index were detected.     

Dual Energy Computed Tomography for the Non‐destructive Analysis of Ancient Ceramics

Ceramics are usually the most common artefact found on any ancient archaeological site. Compositional analysis of this pottery, and characterization of the clay fabrics from which they are made, has the potential to pinpoint sources of manufacture as well as identify trade routes and consumption patterns in the ancient world. Currently, most analytical techniques require the partial or total destruction of the ceramic sample. This research investigates the use of dual energy computed tomography (DECT) to analyse Black Gloss and Vesuvian Sigillata from Pompeii. The results indicate that DECT may be a viable adjunct or alternative to conventional analytical techniques. Importantly, unlike traditional methods, DECT is totally non‐destructive, a highly significant factor when analysing irreplaceable artefacts.     

Material evidence for the use of Attic white-ground lekythoi ceramics in cremation burials

White-ground lekythoi ceramics offer important evidence for funeral practices in Ancient Greece (5th century BC). The images painted-on these oil containers provide the best visual narrative for the events surrounding death, including indications that the vessels themselves were used as part of the funerary rites. However, until now, their specific function and treatment within the funeral ceremony was not well understood. We present here material evidence that the vessels were ritually burned, together with the body of the deceased, during cremation, as evidenced by a diffuse purplish-red discolouration found on many white-ground lekythoi. Through EPMA and μXAS studies, we show that: (1) this characteristic purplish-red discolouration is due to the presence of metallic copper nano-particles embedded in a glassy layer; (2) this metal-glass matrix formed as the result of a high temperature reaction between painted-on Cu-based pigments (e.g., Egyptian blue) and the white-ground ceramic slip; and (3) the reaction occurred under a reducing environment. Given the mortuary context for these vessels, we propose the reduction firing to which the vessels were exposed was that associated with the cremation of the body. The observation of discontinuous formation of the purplish-red discolouration along adjoining fragments supports the hypothesis that the vessels were broken prior to being burned. The majority of lekythoi in museum collections lack information on their original archaeological context, and our data suggest the presence of this purplish-red discolouration may serve as a visual marker for cremation. As such, it is expected our findings will provide a new basis for interpreting how this important class of ceramic, and associated iconographic imagery, relates to Athenian funerary practices and the ancient Greek notion of death.     

Optical spectroscopy as a rapid and low-cost tool for the first-line analysis of glass artefacts: a step-by-step plan for Roman green glass

Archaeometric research on glass artefacts is continuously evolving and is converging towards a multidisciplinary research domain where different types of techniques are applied depending on the questions asked and the circumstances involved. The technique described in this work is optical spectroscopy. The benefit of this technique being the possibility of building up a knowledge database for a large amount of material in a relatively short period of time and with a relatively limited budget. This is of particular interest for the investigation of extensive and/or unexplored glass collections where a first-line analysis of artefacts could facilitate the selection of material needing further and more detailed examination.     

Use of Computed Tomography and Three‐Dimensional Virtual Reconstruction for the Examination of a 16th Century Mummified Dog from a North German Peat Bog

The corpse of a well‐preserved dog was recovered from a peat bog in the region of Burlage, Germany, in 1953. The dog, which dates to the 16th century, retained extensive soft tissue and fur on the postcranial body, although the head is skeletonised. Computed tomography was used to determine the extent of the preservation of the soft tissue, to determine sex and age and to attempt to identify trauma, pathology and potential cause of death. The analysis of the CT data indicated that the dog was an immature or adolescent male. Substantial soft tissue was preserved, including some internal organs. The entire skeleton was present, with the exception of the mandible and parts of the paws; all of the bones were flattened and some were distorted because of demineralisation in the peat. Partial disarticulation of the vertebral column was postmortem, although there was no further evidence of trauma or pathology on the skeleton or soft tissue. The cause of death could not be conclusively determined. To the knowledge of the authors, this dog represents the only known example of a complete historical nonhuman bog body with preserved soft tissue. Copyright © 2011 John Wiley & Sons, Ltd.