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  • Author: Xiaodong Peng x
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Xuesong Fu, Yan Yang, QuanYang Ma, Xiaodong Peng and Tiancai Xu

Abstract

Mg-0.5Si-xSn (x=0.95, 2.9, 5.02wt.%) alloys were cast and extruded at 593K (320 oC) with an extrusion ratio of 25. The microstructure and mechanical properties of as-cast and extruded test alloys were investigated by OM, SEM, XRD and tensile tests. The experimental results indicate that the microstructure of the Mg-0.5Si-xSn alloys consists of primary α-Mg dendrites and an interdendritic eutectic containing α-Mg, Mg2Si and Mg2Sn. There is no coarse primary Mg2Si phase in the test alloys due to low Si content. With the increase in the Sn content, the Mg2Si phase was refined. The shape of Mg2Si phase was changed from branch to short bar, and the size of them were reduced. The ultimate tensile strength and yield strength of Mg-0.52Si-2.9Sn alloy at the temperature of 473K (200 oC) reach 133MPa and 112MPa respectively. Refined eutectic Mg2Si phase and dispersed Mg2Sn phase with good elevated temperature stability are beneficial to improve the elevated temperature performance of the alloys. However, with the excess addition of Sn, large block-like Mg2Sn appears around the grain boundary leading to lower mechanical properties.

Open access

Peng-Fei Han, Zhi-Liang Zhang, Tao-Yu Chen, Rui-Peng Zhao, Rong Zhang, Xiao-Dong Li, Peng-Cui Li, Lei Wei, Zhi Lv and Xiao-Chun Wei

Abstract

The main pathological change in post-traumatic osteoarthritis (PTOA) is cartilage degeneration, which is closely related to inflammation and oxidative stress. Inflammation can cause degeneration of articular cartilage. Cartilage degeneration can also stimulate the progression of inflammation. It has been found that inflammatory cytokines can participate in the pathological process of cartilage degeneration through multiple signaling pathways, mainly mitogen-activated protein kinase, nuclear transcription factor kappa B, and Wnt–β-catenin signal transduction pathways. This review aimed at exploring the relationship between PTOA and inflammation-related cytokines by introducing the role of proinflammatory cytokines in chondrocyte destruction and extracellular matrix degradation.

Open access

Xiao-Dong Zhang, Yi-Fang Feng, Xu Zhang, Mi Tian, Tao Wu, Peng-Fei Ye, Wei Zhang, Yue-Yun Ding, Zong-Jun Yin and Ming-Xing Chu

Abstract

To justify the function of miRNAs in reproductive regulation in swine, the expression of miR-145, miR-429 and their related genes were studied in reproductive tissues of sows. Wannan black pig and Yorkshire pigs with extremely high (n=6) and low (n=6) litter size were sampled, and real-time quantitative PCR (qPCR) was performed on tissue samples from ovaries, uterus, oviduct, hypothalamus, and pituitary. The results indicated that miR-145, miR-429, and zinc finger E-box binding homeobox 1 gene (ZEB1) were expressed significantly different in Wannan black pig and Yorkshire pigs. In pigs with different fecundity, miR-145 in the uterus was expressed significantly lower in pigs with high litter size, than in pigs with low litter size. The miR-429 expression in the oviduct and pituitary of pigs with high litter size was significantly higher compared with tissues sampled from pigs with low litter size. The ZEB1 expression in the pituitary was lower in pigs with high litter size in comparison to pigs with low litter size, while luteinizing hormone beta subunit (LHβ) showed the opposite pattern of expression. In conclusion, miR-145 and miR-429 were differently expressed in pigs with high and low litter size and might have a role in affecting litter size of sows.