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Water inrush at floor area is a natural hazard during coal mining. Especially in the northern coalfield of China, more than 55% of coal mines are threatened by water inrush at floor area. The hazard of water inrush is becoming more serious with increasing mining depth. In this paper, the deformation and failure behavior at floor area in deep longwall mining site were analyzed. The correlation between the floor failure and main roof breakage was studied using kinematics theory. Meanwhile, the impact loads of cantilever beam breakage on the floor area at both longwall face and gob area were calculated. Combining with "Pressure arch hypothesis", the compression and unloading mechanics processes at floor area were analyzed, and the unloading deformation model of floor structure after the breakage of main roof was established as well. In addition, the correlation between unloading deformation at floor area and the main roof breakage, mining depth and unloading stresses were also obtained. Finally, these studies have been verified by using micro-seismic monitoring data in deep longwall mining site. The results show that the impact loads are proportional to the span and loads of cantilever beam. After the breakage of cantilever beam, the impact loads were transferred to the floor area at longwall face side and gob side, and the rock masses at both sides were failed in compression. Consequently, the position of back arch foot of the pressure arch was rapidly transformed into the contact gangue zone at gob area from the last breakage position of main roof. While as the unloading stress of rock masses inside of the floor pressure arch is increasing, the depth of unloading fracture and heave below longwall face are greater than those before cantilever beam breakage. In addition, the unloading deformation at surface floor increases nonlinearly with the increase in mining depth and unloading stresses. [ABSTRACT FROM AUTHOR]

Avian leukosis virus (ALV) is an enveloped retrovirus with a single-stranded RNA genome, belonging to the genus Alpharetrovirus within the family Retroviridae. The disease (Avian leukosis, AL) caused by ALV is mainly characterized by tumor development and immunosuppression in chickens, which increases susceptibility to other pathogens and leads to significant economic losses in the Chinese poultry industry. The government and poultry industry have made lots of efforts to eradicate ALV, but the threat of which remains not vanished. This review provides a summary of the updated understanding of ALV in China, which mainly focuses on genetic and molecular biology, epidemiology, and diagnostic methods. Additionally, promising antiviral agents and ALV eradication strategies performed in China are also included. [ABSTRACT FROM AUTHOR]

Cordyceps militaris is a unique and precious medical fungus in Chinese Cordyceps, which has been widely used as the traditional medicines or as biocontrol agents against pests in China for centuries. Polysaccharides are one of bioactive constituents in Cordyceps militaris with a variety of biological activities, including immunomodulation, antioxidant, anti-tumor, and anti-aging activities, among others. However, natural Cordyceps militaris are very rare and expensive, most of literatures indicated that the polysaccharides were mostly extracted from artificially cultivated fungal fruiting bodies (intracellular polysaccharides) or mycelia fermentation broths (extracellular polysaccharides). Moreover, separation and purification of polysaccharides was a very complicated and cumbersome process. Nevertheless, a large number of polysaccharides were purified and its characterization was elucidated by structure and biological activities. However, the relationship between structure and activity of polysaccharides has not been well established. Therefore, this review detailed the recent advance in several aspects (i.e., extraction, isolation, structure, and bioactivities) of the polysaccharides from fruiting body of Cordyceps militaris. This information could provide theoretical basis for the research on related polysaccharides, and also have important reference value in the field of functional foods and medicine in the future. • C. militaris is one of the best known traditional Chinese medicine and health foods. • Polysaccharide is one of the most important components in C. militaris. • C. militaris polysaccharides exhibited multiple structural features and various bioactivities. • This review focused on the isolation, structural features and bioactivities of C. militaris polysaccharides. [ABSTRACT FROM AUTHOR]