薄喷支护技术在东欢坨矿的试验研究

采用南京所研制的非反应型聚合物粉体材料以薄喷方式取代喷射混凝土的封闭、防风化、防锈蚀功能,是煤矿井下巷道目前较为理想的喷浆封闭、支护选择。本文分析了这种聚合物粉体材料的封闭、支护机理,总结了薄喷技术特点,并根据薄喷技术在开滦(集团)东欢坨矿的试验情况,认识到非反应型薄喷封闭材料可常温水化溶解、附着岩体成膜,并可持续增长强度,且方便输送、施工,施工时低尘,无热量和VOC释放,并达到室内涂料国标环保要求;PF1L型薄喷机采用全密闭、无滑动密封面的结构型式,运转时低尘、且操作方便;喷厚5mm,喷速2m2·min-1,粉尘浓度低于10mg·m-3,用工仅需3人。同时,明确了下一步研发工作重点为:进一步降低粉尘和材料成本;消除喷涂脉冲;提高快凝性、水硬性及进行相应技术条件与规范研究。

Environmental and technological effects on ancient social evolution at different spatial scales

The rise and fall of ancient cultures and civilizations is a hotly debated topic that has generated disagreements and disputes. In this paper we summarize some case studies on the abandonment of ancient sites, the prosperity and collapse of ancient cultures, and demographic changes, as well as the influence of environment and technology during the prehistoric and historic periods. We then suggest that the dominant influencing factors for the evolution of ancient societies vary by spatial scale.At the local scale, sudden disasters are critical factors leading to the destruction and abandonment of large settlements. On a regional scale, climatic variations(e.g., droughts or cold events lasting for decades or centuries) are important factors that induce the collapse of ancient civilizations and mass migrations, while an enduring and stable optimal climate facilitated the prosperity of ancient civilizations. On a global scale, major technological innovations and their dispersion lasting for centuries and even millennia are major catalysts for population growth and social development. Lastly, we illustrate a possible mechanism under which environmental and technological factors played a critical role in ancient human survival and social evolution on different spatial scales.

Multiple evidences indicate no relationship between prehistoric disasters in Lajia site and outburst flood in upper Yellow River valley, China

All around the world, ancient legends exist about the Great Flood, and the influence of the Great Flood in human evolutionary history is a hotly debated topic. In China, the legend of the prehistoric Great Flood and Yu the Great's flood control has a long history and is considered to be closely linked to the establishment of the Xia Dynasty. However, there is a lack of solid scientific evidence. Against this issue, some scholars have proposed that an earthquake around 1920 BCE in the Guanting Basin along the upper reaches of the Yellow River led to the creation of a lake by damming in the Jishi Gorge and that the outburst of water from that lake led to the massive flood in the Yellow River region. These studies provided new scientific evidence for the Chinese legend. In this paper, we date skeletal samples embedded in earthquake sand blasting from the Lajia site, analyze remains from natural disasters(such as earthquakes and floods) and also archaeological remains. In addition, we compared the skeletal samples dating with that of sediments from the dammed-up lake. Our results are inconsistent with those of previous scholars. The earthquake at the Lajia site occurred no earlier than 1800 BCE, and the dammed-up lake in Jishi Gorge had disappeared by 3600 BCE. Thus, the formation and outburst of the dammed lake, the sudden death of ancient humans at the Lajia site and the ancient earthquake were independent events occurring at different times. In addition, the massive flood in the upper reaches of the Yellow River did not actually happen. Thus, we argue against and invalidate the hypothesis that the massive flood was related to Yu the Great's flood control and the establishment of the Xia Dynasty.

Prehistoric agriculture development in the Yunnan-Guizhou Plateau, southwest China： Archaeobotanical evidence

The origin, development and expansion of prehistoric agriculture in East Asia have been widely investigated over the past two decades using archaeobotanical analysis from excavated Neolithic and Bronze Age sites. Research on prehistoric agriculture has predominantly focused in the valleys of the Yellow River and the Yangtze River. Agricultural development during the Neolithic and Bronze Age periods in the Yunnan-Guizhou Plateau of southwest China, an important passageway for human migration into Southeast Asia, still remains unclear. In this paper, based on macrofossil and microfossil analysis and radiocarbon dating at the Shilinggang site, we investigate plant subsistence strategies in the Nujiang River valley during the Bronze Age period. Combined with previous archaeobotanical studies in the Yunnan-Guizhou Plateau, we explore agricultural development processes in this area during the Neolithic and Bronze Age. Our results indicate that rice and foxtail millet were cultivated in Shilinggang around 2500 cal a BP. Three phases of prehistoric agricultural development in the Yunnan-Guizhou Plateau can be identified: rice cultivation from 4800–3900 cal a BP, mixed rice and millet crop(foxtail millet and broomcorn millet) cultivation from 3900–3400 cal a BP, and mixed rice, millet crop and wheat cultivation from 3400–2300 cal a BP. The development of agriculture in the Yunnan-Guizhou Plateau during the Neolithic and Bronze Age periods was primarily promoted by prehistoric agriculture expansion across Eurasia, agricultural expansion which was also affected by the topographic and hydrological characteristics of the area.

华莱士:自然选择学说的共同发现者

简述了英国著名的博物学家、人类学家、探险家和生物学家华莱士的探险经历及其在进化生物学、生物物理学领域的贡献,让公众更为全面地认识被誉为生物地理学之父的华莱士在自然选择学说提出中取得的重要成就。