The pure magnesium was fabricated by directional solidification, and the effect of the distribution characteristics of magnesium oxide (MgO) on the mechanical properties of pure magnesium was investigated. The statistical results showed that the area fraction, number and size of MgO were decreased gradually from the top region ingot to the bottom region ingot, and these reflected the advantages of directional solidification technology in the controllability of MgO distribution characteristics. The top parts of magnesium ingots have the highest tensile strength (44 MPa), which is mainly due to the presence of a large amount of the coarse MgO. Though the coarse MgO increases the strength obviously, it has harm for the ductility of magnesium. The top parts of magnesium ingots have higher ultimate tensile strength, but lower failure strain (13% and -21% respectively) than the ingot at the center. These results indicate that if the suitable size and amount of MgO existed in magnesium matrix, it could avoid the disadvantages of MgO and provide positive effect for both the strength and ductility of magnesium alloys.

Abstract Zirconium (Zr) is an essential element in Mg-Zn and Mg-Zn-Y system magnesium alloys. In this study, an interesting phenomenon that the content of Zr element could influence the size and the morphology of the long period stacking ordered (LPSO) phases, which has never been reported by previous works before. The Mg98.5-xZn0.5Y1Zrx (x =0, 0.1, 0.2 and 0.3 at. %) magnesium alloys were fabricated by directional solidification, and the effects of the Zr content on the distribution characteristics of the bulk LPSO phases (18R) and the lamellar LPSO phases (14H) were investigated. The directional solidification technology showed good controllability in LPSO phase’s distribution, and the morphology of LPSO phases in Mg98.5-xZn0.5Y1Zrx (x =0, 0.1, 0.2 and 0.3 at. %) alloys were observed clearly. The results showed that the amount and the morphology of the 14H and 18R LPSO phases within grains continuously decreased with the Zr content increasing. The continuous 14H lamellar structure changed to discontinuous. In addition, Zr element exhibited purification ability on the grain boundaries and refined effect on the 14H and 18R LPSO phases. This can be attributed to the influence of Zr atoms on stacking fault energy (SFE) and the attraction of Zr atoms to Mg atoms.

Abstract The goal of this research was to investigate the linkage disequilibrium between rs9263726 and HLA-B*58:01 in different Chinese ethnic groups (Han, Tibet, and Hui) and to study the feasibility of rs9263726 replacing HLA-B*58:01 as an efficient indicator of potential allopurinol hypersensitivity syndrome. In this study, rs9263726 and HLA-B*58:01 were detected in all samples. For samples of individuals whose rs9263726 genotypes were not consistent with HLA-B*58:01, we did high-resolution typing of HLA-B gene to further confirm the correlation of rs9263726 genotype and special HLA-B alleles. We confirmed that the linkage disequilibrium between rs9263726 and HLA-B*58:01 was more significant in the Han ethnic group (r2=0.886, D’=1.0) than in the Tibet and Hui ethnic groups (for Tibetan, r2=0.606, D’=0.866; for Hui, r2=0.622, D’=0.924). For Han Chinese, samples with the GG genotype of rs9263726 did not carry HLA-B*58:01, while AA genotype samples were homozygous carriers of HLA-B*58:01. However, GA genotype samples of rs9263726 required a more sophisticated HLA-B genotyping assay before it was possible to identify whether they were HLA-B*58:01 carriers or not. For Tibetan and Hui, the linkage disequilibrium between rs9263726 and HLA-B*58:01 was not significant. Therefore, rs9263726 cannot replace HLA-B*58:01 in these two groups.