铝含量对AZ系列镁合金机械加工性能的影响

研究铝含量对AZ系列铸造铝合金机械加工性能的影响。为评价该合金的机械加工性能,测量切削操作过程中的切削力以及表面粗糙度,以及研究显微组织和拉伸性能。结果表明：添加2%铝含量的镁合金具有最佳的拉伸性能。随着铝含量增加到2%以上,由于晶界上析出金属间化合物β-Mg17Al12,切削力会随延展性的降低而降低。切削力也会随着切削速度的增加而增大,这是由于在加工过程中切削工具的尖端有侧面生成。     

Genetic polymorphism of kappa‐casein,growth hormone and prolactin genes in Turkish native cattle breeds

A total of 259 cattle of four Turkish native cattle breeds, East Anatolian Red (EAR), South Anatolian Red (SAR), Turkish Grey (TG) and Anatolian Black (AB), Holstein and Brown Swiss (BS) breeds were genotyped for kappa‐casein (CSN3), bovine growth hormone (GH1) and prolactin (PRL) polymorphism by the polymerase chain reaction and restriction length polymorphism (PCR‐RFLP). The degree of genetic differentiation between populations F_ST was calculated as 0.053 and was found to be significant (P < 0.001). According to the genetic distance values (Nei), the highest genetic difference was found between SAR and EAR in four Turkish native cattle breeds and this difference was significant.