Black crusts, such as dust deposit and smoked smudge, are the main pollutants in Yungang Grottoes, the world famous Buddhist heritage site. It is always considered that the black crust should be removed during the conservation process of stones. In this paper, the investigation of the role of smoked crust on the Yungang sandstones was performed to verify if the smoked layer on the stone surface would be harmful or protective. The results of SO2 corrosion experiments with and without water both show that the samples covered with smoked layer can play a protective role on the sandstones, which means that the smoked layer on the stones can prevent the attack of SO2 and water, the major deterioration agents in Yungang area. The multi-factor deterioration cycle experiments, including salt crystallization, freeze–thaw damage, wet–dry cycle and acid corrosion, also indicate that the smoked samples are less deteriorated and salt crystallization is the most severe damage to the sandstones. 相似文献
The aim of this paper is to apply kernel density estimates (KDEs) to the visualization and interpretation of lead isotope data from bronze assemblages found along the northern border of central China, here designated as the Arc. New lead isotope analyses of 30 leaded tin–bronze artefacts from the Wangdahu cemetery (c.500–300 bc ) in the Ningxia Hui Autonomous Region, north‐west China, provide the basis for the discussion. By using multivariate KDEs and the calculated likelihood of the overlap, the present work shows that the Wangdahu objects feature a unique linear array of isotope ratios, representing an important element of overall bronzes from the Arc in the first millennium bc . This characteristic isotope signature is fundamentally different from that of Dajing ores in north‐east China, as well from that of early Qin bronzes in Shaanxi and Gansu provinces. This suggests that a variety of metal resources were utilized by peoples living in the Arc. The KDE approach thus proves effective at presenting and comparing lead isotope data. 相似文献
Shen, Y. & Wang, X.L., July 2016. Howchinia Cushman, 1927 (Foraminifera) from the Mississippian Bei’an Formation and its distribution in South China. Alcheringa 40, xxx–xxx. ISSN 0311-5518.
Howchinia Cushman is a useful biostratigraphic marker for Mississippian rocks. In South China, Howchinia has been reported from four sections: the Bei’an, Baping, Naqing and Yashui sections; with high species diversity in the Bei’an section. Ten species from the Mississippian Bei’an Formation in the Bei’an section are described in this paper: Howchinia bradyana, H. beleutensis, H. gibba, H. plana, H. convexa, H. subconica, H. subplana, Howchinia sp. A, Howchinia sp. B. and Howchinia beianensis sp. nov. Howchinia ranges from late Visean to early Bashkirian in South China. Howchinia species inhabited both shallow-water and relatively deep-water environments.
Yang Shen [shenybj@126.com] and Xun-Lian Wang [wxl@cugb.edu.cn], State Key Laboratory of Biogeology and Environmental Geology, China University of Geosciences, 29 Xueyuan Road, Beijing 100083, PR China.相似文献