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      • KCI등재

        Prediction of Stress Intensity Magnifi cation Factors of a Weld Toe Crack in Load-Carrying Cruciform Fillet Welded Joints Under Axial Loading

        Haisheng Zhao,Sengtjhen Lie,Yao Zhang 한국강구조학회 2019 International Journal of Steel Structures Vol.19 No.3

        Load-carrying cruciform fi llet welded joint is commonly encountered in on-shore and off shore structures. In this study, the stress intensity magnifi cation factors ( M km ) of such confi guration containing a 3-D semi-elliptical surface crack at the weld toe are analysed using 3-D fi nite element analyses. Due to the non-penetrating fi llet welds at the intersection of the main plate and transverse stiff ener, the M km values are found to be much larger than the corresponding results of non-load-carrying cruciform welded joints. Therefore, a new set M km equations for load-carrying joints are built up using multiple regression analyses, and statistical analyses are carried out to validate the goodness of fi t of these equations. It is noted that the existing British Standard 7910 (BS 7910) assessment equation produces an over-conservative prediction on M km values as compared with the newly proposed M km equations, and the largest over-estimation percentage diff erence is as high as 257.8%.

      • KCI등재

        Detrimental effects of lipopolysaccharides on maturation of bovine oocytes

        Shanjiang Zhao,Yunwei Pang,Xueming Zhao,Weihua Du,Haisheng Hao,Huabin Zhu 아세아·태평양축산학회 2019 Animal Bioscience Vol.32 No.8

        Objective: Gram-negative bacteria lipopolysaccharide (LPS) has been reported to be associated with uterine impairment, embryonic resorption, ovarian dysfunction, and follicle retardation. Here, we aimed to investigate the toxic effects of LPS on the maturation ability and parthenogenetic developmental competence of bovine oocytes. Methods: First, we developed an in vitro model to study the response of bovine cumulus-oocyte complexes (COCs) to LPS stress. After incubating germinal vesicle COCs in 10 μg/mL of LPS, we analyzed the following three aspects: the expression levels of the LPS receptor toll-like receptor 4 (TLR4) in COCs, activities of intracellular signaling protein p38 mitogen-activated protein kinase (p38 MAPK) and nuclear factor-kappa B (NF-κB); and the concentrations of interleukin (IL)-1β, tumor necrosis factor (TNF)-α, and IL-6. Furthermore, we determined the effects of LPS on the maturation ability and parthenogenetic developmental competence of bovine oocytes. Results: The results revealed that LPS treatment significantly elevated TLR4 mRNA and protein expression levels in COCs. Exposure of COCs to LPS also resulted in a marked increase in activity of the intracellular signaling protein p-p38 MAPK and NF-κB. Furthermore, oocytes cultured in maturation medium containing LPS had significantly higher concentrations of the proinflammatory cytokines IL-1β, TNF-α, and IL-6. LPS exposure significantly decreased the first polar body extrusion rate. The cytoplasmic maturation, characterized by polar body extrusion and distribution of peripheral cortical granules, was significantly impaired in LPS-treated oocytes. Moreover, LPS exposure significantly increased intracellular reactive oxygen species levels and the relative mRNA abundance of the antioxidants thioredoxin (Trx), Trx2, and peroxiredoxin 1 in oocytes. Moreover, the early apoptotic rate and the release of cytochrome C were significantly increased in response to LPS. The cleavage, morula, and blastocyst formation rates were significantly lower in parthenogenetically activated oocytes exposed to LPS, while the incidence of apoptotic nuclei in blastocysts was significantly increased. Conclusion: Together, these results provide an underlying mechanism by which LPS impairs maturation potential in bovine oocytes.

      • SCIESCOPUSKCI등재

        Effects of epigallocatechin-3-gallate on bovine oocytes matured in vitro

        Huang, Ziqiang,Pang, Yunwei,Hao, Haisheng,Du, Weihua,Zhao, Xueming,Zhu, Huabin Asian Australasian Association of Animal Productio 2018 Animal Bioscience Vol.31 No.9

        Objective: Epigallocatechin-3-gallate (EGCG) is a major ingredient of catechin polyphenols and is considered one of the most promising bioactive compounds in green tea because of its strong antioxidant properties. However, the protective role of EGCG in bovine oocyte in vitro maturation (IVM) has not been investigated. Therefore, we aimed to study the effects of EGCG on IVM of bovine oocytes. Methods: Bovine oocytes were treated with different concentrations of EGCG (0, 25, 50, 100, and $200{\mu}M$), and the nuclear and cytoplasmic maturation, cumulus cell expansion, intracellular reactive oxygen species (ROS) levels, total antioxidant capacity, the early apoptosis and the developmental competence of in vitro fertilized embryos were measured. The mRNA abundances of antioxidant genes (nuclear factor erythriod-2 related factor 2 [NRF2], superoxide dismutase 1 [SOD1], catalase [CAT], and glutathione peroxidase 4 [GPX4]) in matured bovine oocytes were also quantified. Results: Nuclear maturation which is characterized by first polar body extrusion, and cytoplasmic maturation characterized by peripheral and cortical distribution of cortical granules and homogeneous mitochondrial distribution were significantly improved in the $50{\mu}M$ EGCG-treated group compared with the control group. Adding $50{\mu}M$ EGCG to the maturation medium significantly increased the cumulus cell expansion index and upregulated the mRNA levels of cumulus cell expansion-related genes (hyaluronan synthase 2, tumor necrosis factor alpha induced protein 6, pentraxin 3, and prostaglandin 2). Both the intracellular ROS level and the early apoptotic rate of matured oocytes were significantly decreased in the $50{\mu}M$ EGCG group, and the total antioxidant ability was markedly enhanced. Additionally, both the cleavage and blastocyst rates were significantly higher in the $50{\mu}M$ EGCG-treated oocytes after in vitro fertilization than in the control oocytes. The mRNA abundance of NRF2, SOD1, CAT, and GPX4 were significantly increased in the $50{\mu}M$ EGCG-treated oocytes. Conclusion: In conclusion, $50{\mu}M$ EGCG can improve the bovine oocyte maturation, and the protective role of EGCG may be correlated with its antioxidative property.

      • KCI등재

        HVOF Spray Performance Optimization Analysis and Experimental Research of WC–12Co Coating on Ti Alloy

        Xinxue Chen,Chang Li,Siyu Li,Xing Han,Haisheng Jiang,Xiaoyu Zhao 대한금속·재료학회 2023 METALS AND MATERIALS International Vol.29 No.12

        TC18 titanium alloy, with low density, high strength and corrosion resistance, is a significant material for the main loadbearingcomponents of aircraft landing gear and other aviation structures. However, its corrosion resistance and wear resistanceare insufficient when it is serviced in the extreme corrosion environments such as sea salt spray and hygrothermal,which greatly affects its wide application. It is significant to design and develop high-quality anti-corrosion and wear resistantcoatings for TC18 titanium alloy. High Velocity Oxygen Fuel (HVOF) spraying WC–12Co is an ideal strengthening methodto replace surface chromium plating. Quantitatively evaluating the influence of spraying process parameters on the coatingquality is the key to prepare high-quality coatings. In this study, a numerical model of HVOF spraying WC–12Co wasestablished with JP5000 spray gun. The spray combustion reaction model and discrete phase model were solved to reveal theevolution characteristics of combustion flame flow and particle flight behavior in the spraying process. Based on the responsesurface method, the optimum spraying process parameters were determined, and the WC–12Co coatings were prepared. Onthis basis, the coating was tested by the SEM, XRD, hardness, friction and wear, salt spray corrosion and seawater corrosion. The corrosion resistance and wear resistance of the WC–12Co coating were comprehensively evaluated. The experimentshows that the WC–12Co coating prepared by HVOF spraying has great performance, which can effectively improve theprotective performance of TC18 substrate.

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