CCN1 gene polymorphisms associated with atrial septal defect susceptibility in Northwest Chinese population from different high-altitude areas

High-altitude hypoxic environment exposure is considered as one of the risk factors for congenital heart disease (CHD), but the genetic factors involved are still unclear. CCN1, one of the synergistic molecules in the hypoxic response, is also an indispensable molecule in cardiac development. Considering that CCN1 may play an important role in the occurrence of CHD in high-altitude areas, we investigated the association between CCN1 polymorphisms and CHD susceptibility in Northwest Chinese population from different high-altitude areas. We conducted a case-control study with a total of 395 CHD cases and 486 controls to evaluate the associations of CCN1 polymorphisms with CHD risk. Our results showed that the protective alleles rs3753793-C (OR = 0.59, 95% CI = 0.42–0.81, P = 0.001), rs2297141-A (OR = 0.66, 95% CI = 0.49–0.90, P = 0.001) and C-A haplotype of rs3753793-rs2297141 (OR = 0.58, 95% CI = 0.42–0.82, P = 0.002) were significantly associated with a decreased atrial septal defect (ASD) risk. Further subgroup analysis in different geography populations revealed robust association of SNP rs2297141 with ASD risk in a Han population residing in high-altitude of 2500–4287 m. We also found that the frequency of protective alleles was higher in high-altitude population, and the alleles were responsible for the difference of oxygen physiology related erythrocyte parameters in different high-altitude populations. rs3753793-C and rs2297141-A are likely related to high altitude and hypoxia adaptation, which may also be the reason for the association between CCN1 polymorphism and ASD risk.

Effect Pouring Temperature on Casting Defect Susceptibility of Hot Tearing in Metal Alloy Al-Si

Hot tearing is one of metal casting defects and often found in the casting products such as cracks on the surface. Solidifaction metal causes a thermal contraction and shrinkage, when the contraction and shrinkage occurs if a metal alloy is restrained by mold design, it will effect hot tearing. Hot tearing is influenced by several factors, including the chemical composition of the alloy, the casting temperature, mold temperature, mold constraint, fast or slow solidifaction, non uniform solidifaction, and so on. This study aimed to obtain a certain temperature that cause the maximum of hot tearing defects, so it can be recommended to the metal casting industry in aluminum-silicon material to avoid the casting temperature. Three variations of the casting temperature used in this study including 710 oC, 760 oC and 810 oC. The material used in this study is an alloy of Al-1.19% Si (percent by weight). The method used is a visual method using mold CRCM (Constrain Casting Rod Modified) Horizontal used for the index analysis of HTS (Hot tearing Susceptibility). The results gotten include the hot tearing increases with the increasing of casting temperature, and it decreases with the decreasing the casting pouring. The maximum of hot tearing index is 45 HTS at 760 oC for casting temperature. Tear formed on products from smooth categories (hairline cracks) to the complete categories (broken specimen).