瓷器文物修复中环保作旧材料性能比较研究

瓷器文物修复中作旧处理是修复中的关键步骤,作旧处理的好坏,关系到修复后瓷器的保存时效。传统作旧处理中所用的硝基清漆易于黄变,且所用稀释剂具有一定的污染性。为筛选环保且较耐久的瓷器修复作旧材料,以环保水性材料为主,选用水性氟碳树脂DF-01、水性氟碳乳液、水性木器清面漆和水性木器清底漆四种水性高分子材料分别作为瓷器修复作旧处理过程中的粘接材料,按照传统修复方法,以市售瓷板为处理对象,对其进行作旧处理。然后将上述样品分别进行干热、湿热和氙灯老化,通过测试上述样品老化前后的色差和光泽度,表征了上述材料的耐老化性能。结果表明,与传统材料硝基清漆相比,实验所选用的水性高分子材料具有较好的耐热老化、抗氙灯老化和抗湿热老化能力,且在操作过程中无味,有望解决传统瓷器文物修复材料易于黄变且对环境污染大的难题,具有一定的应用前景。     

Experimental Heating of Moravian Cherts and its Implication for Palaeolithic Chipped Stone Assemblages

The applicability of colour, magnetic susceptibility and remanent magnetization measurements for the identification of heated or accidentally burned Palaeolithic cherts from Moravia (Czech Republic) is tested in this study. We conclude that all these methods are usable. Colour changes are best detectable in materials heated at between 250–350°C, while magnetic susceptibility and remanent magnetization change at higher temperatures, closer to 600°C. This latter temperature, however, is usually destructive for cherts and is probably evidenced by accidentally burned artefacts. With the use of the three methods, we managed to identify three probably heated chert artefacts from two early Upper Palaeolithic assemblages from Moravia.     

A biface and blade core efficiency experiment: implications for Early Paleoindian technological organization

Early Paleoindians often are described as highly mobile hunter–gatherers who employed lithic technologies designed to minimize stone transport costs. We experimentally reduced blade and bifacial cores and found both reduction strategies to be equally efficient for the production of useable flake blanks. Further, when compared to similar core reduction experiments, the results of this study showed no significant differences in core efficiency between bifacial, prismatic blade, and wedge-shaped blade core reduction. Biface and blade cores with initial weights greater than 1000 g produced useable flakes as efficiently as informal cores. However, bifacial and blade core efficiency decreased with initial core weight. When considered in terms of Early Paleoindian technological organization, differences in core efficiencies suggest that Folsom groups employed core reduction strategies designed to minimize stone transport costs, but Clovis groups did not.     

Variability in bifacial technology at Elandsfontein,Western cape,South Africa: a geometric morphometric approach

This study applies a new three-dimensional measurement technique to determine the major source of variation in the Acheulian bifacial tool collection from the Middle Pleistocene site of Elandsfontein, South Africa. This three-dimensional technique is compared with conventional two-dimensional methods to investigate which methods capture morphological variation in the assemblage most comprehensively. Additionally, a set of experimentally produced bifacial tools are incorporated into the analyses to isolate the behavioral pattern underpinning identified variation in the archaeological assemblage. The interpretative breadth of current models explaining morphological variation in bifacial tools is then tested against the pattern identified in the Elandsfontein assemblage. Variation appears to be related to the consistent application of a specific reduction strategy associated with the early stages of bifacial tool manufacture. The intensity with which this strategy was applied seems to have been mediated by the availability of raw material that was suitable for the production of large bifacial tools.     

Assessing the effects of conservation treatments on short sequences of DNA in vitro

Little is known about what effects conservation treatments used to preserve human and animal hard and soft tissues have on DNA preservation. We have developed a method to assess quantitatively the extent of lesions or strand breakage caused by conservation treatments on short sequences of DNA in vitro. The method developed enables the determination of the percentage of DNA preserved following exposure to a conservation treatment solution relative to control samples, thereby allowing the direct comparison of treatments based upon their preserving/damaging effects on a DNA sequence. Forty-three chemicals commonly used in the preparation and/or conservation of human and/or animal remains were examined. We found that the majority were damaging, in particular and as expected, acidic treatments and treatments carried out at elevated temperatures. A few, primarily organic solvents, were not damaging. The approach we have adopted can be applied to screen other treatments either used in the past or for future conservation applications as they are developed to assess their effects on DNA. How these results should be interpreted in terms of conservation and sampling is also discussed.     

Experimental analysis of the practical limits of lithic refitting

We report on the results of an experiment aimed at determining the effects of experience/aptitude, lithic reduction type (biface v. core), and flake size cut-offs on different rates of success in refitting studies. We found that experience matters, but that there can be large differences in aptitude for refitting; that cores are easier to refit than bifaces; and that the effort of refitting increases considerably for flakes smaller than 5–6 g. We propose the use of an asymptotic equation fit to a cumulative curve as a way to determine when a study has reached the point of diminishing returns for a given flake size cut-off, and to help determine differences in aptitude for refitting.     

Short communication: Two additional Egyptian Neolithic burials exhibiting unusual mortuary treatment of teeth

In a prior report we described human remains from the Neolithic cemetery at Gebel Ramlah, Egypt, with evidence of purposeful tooth replacement. Two crania, which were apparently disturbed by later burials, were found to contain several teeth that had been incorrectly reinserted into the jaws. Such treatment was suggested to be unique. Recent work at the site revealed a similarly unusual find. Two adult male skeletons, evidently displaced in antiquity, also had several teeth loosened from their jaws; however, instead of attempting to reinsert them, the Neolithic gravedigger(s) placed the teeth into the right orbit of one cranium and the nasal aperture of the other. Such placement, as well as the general state of these burials, ruled out subsequent looting or taphonomic factors as causative agents. We previously speculated that tooth replacement represented an attention to detail while attempting to re‐inter the remains in as complete a state as possible. This assumption may hold true for the present situation, but there are other plausible interpretations; for example, it might indicate animosity toward the individuals, an attempt at humour, or perhaps something less purposeful (e.g. they provided convenient receptacles). Whichever the case, the cemetery continues to yield heretofore unknown, and valuable, information about mortuary and other data relating to these prehistoric desert peoples. Copyright © 2005 John Wiley & Sons, Ltd.     

Thermal springs and heat flow in North America

Thermal springs are commonly thought to be an indicator of geothermal resource potential. However, there have been few analyses of the relationship between thermal springs and the underlying thermal regime. An examination of temperature and discharge rates for a large database of thermal springs in North America demonstrates that there is not a simple relationship between these measurements made at the surface and subsurface heat flow. Hydrogeological factors appear to exert strong controls on the temperature and discharge at these springs and should be carefully considered in geothermal resource assessments.