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Yang Y.-P.,Central South University | Yang Y.-P.,Xiang Xi National Vocational Technical College | Yan H.-Z.,Central South University | Yan H.-Z.,Xiang Xi National Vocational Technical College
Cailiao Kexue yu Gongyi/Material Science and Technology | Year: 2012

In order to reduce thermal stress of large-scale zinc ingot die and extend its using life, by FEM, influences of cooling ribs and wall thickness and corner radius and upper flange to die's stress field were analyzed. Simulating results show that stress of upper die can be effectively reduced and cracks can be prevented by rationally allocating various part's wall thickness of zinc die. In addition, when designing zinc die's structure, it is suggested that cooling ribs should not be appropriated, corner radius should be larger, upper flange should not be set. The results can be theory reference for zinc ingot and aluminium ingot die designing and making. Source

Li F.,Hunan Agricultural University | Hu T.,Hunan Agricultural University | Duan N.C.,Hunan Agricultural University | Li W.Y.,Xiang Xi National Vocational Technical College | And 5 more authors.
Journal of Helminthology | Year: 2016

The present study examined sequence variability in two mitochondrial DNA (mtDNA) regions, namely cytochrome c oxidase subunit 1 (cox1) and NADH dehydrogenase subunit 1 (nad1), and internal transcribed spacer (ITS) of nuclear ribosomal DNA (rDNA) among Oesophagostomum asperum isolates from goats in Hunan Province, China. A portion of the cox1 (pcox1), nad1 (pnad1) genes and the ITS (ITS1+5.8S rDNA+ITS2) rDNA were amplified by polymerase chain reaction (PCR) separately from adult O. asperum individuals and the representative amplicons were subjected to sequencing from both directions. The lengths of pcox1, pnad1 and ITS rDNA were 366 bp, 681 bp and 785 bp, respectively. The A+T contents of gene sequences were 71.5-72% for pcox1, 73.7-74.2% for pnad1 and 58-58.8% for ITS rDNA. Intra-specific sequence variations within O. asperum were 0-1.6% for pcox1, 0-1.9% for pnad1 and 0-1.7% for ITS rDNA, while inter-specific sequence differences among members of the genus Oesophagostomum were significantly higher, being 11.1-12.5%, 13.3-17.7% and 8.5-18.6% for pcox1, pnad1 and ITS rDNA, respectively. Phylogenetic analyses using combined sequences of pcox1 and pnad1, with three different computational algorithms (Bayesian inference, maximum likelihood and maximum parsimony), revealed distinct groups with high statistical support. These findings demonstrated the existence of intra-specific variation in mtDNA and rDNA sequences among O. asperum isolates from goats in Hunan Province, China, and have implications for studying molecular epidemiology and population genetics of O. asperum. Copyright © Cambridge University Press 2014. Source

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