B对过共晶Al-25%Si合金组织和力学性能的影响

采用B对过共晶Al-25%Si合金进行变质处理。结果表明,B变质剂对Al-25%Si合金中的初晶硅有着明显的细化作用,当B的添加量为0.08%时,初晶硅的晶粒尺寸最小,初晶硅的晶粒尺寸从未变质的90μm~120μm细化至40μm~60μm,初晶硅由五星花瓣状或不规则复杂多角形状变成板片状,其尖角钝化,长针状的共晶硅组织的细化效果不明显。XRD和SEM分析表明,在变质后的Al-25%Si合金中未有新相生成。力学性能测试表明,变质后合金的力学性能提升较为明显。当变质剂B的添加量为0.8%时,过共晶Al-25%Si合金的抗拉强度值最大,合金的抗拉强度从变质前的151 MPa提高到变质后的187 MPa,提高了23.0%;合金的伸长率也有较大变化,从未变质1.8%提高到变质后的4.2%。

Effect of Atorvastatin on the Expression of Inflammatory Cytokines in Rats with Klebsiella Pneumonia

Objective:To explore the effect of atorvastatin on the expression of inflammatory cytokines in rats with Klebsiella pneumonia.Methods:90 healthy SPF-grade SD rats were randomly divided into three groups:atorvastatin group,model group and blank group(with 10 rats in each group),30 rats in each treatment period(3,6,9 d).A rat model of Klebsiella pneumonia was constructed,in which the blank group and the model group were given the same volume of saline,while the atorvastatin group was given 10 ml/kg of atorvastatin by intraperitoneal instillation.The rats were killed on the 10th day after administration,and the lung tissue was extracted to detect the pathological results and the expression of inflammatory cytokines was detected in serum.Results:Lung histopathology showed that lung histopathology and fibrosis were improved in atorvastatin group,and alveolar structure integrity≥50%and collagen fiber precipitation≤10%in atorvastatin group indicated that the model was successful.The expression of inflammatory cytokines showed that the levels of IL-6,TNF-αand TGF-βin the atorvastatin group and the model group were significantly increased compared with the blank group,with statistically significant differences(P<0.05).The levels of IL-6,TNF-αand TGF-βin atorvastatin group were lower than those in model group,and the levels of IL-10 in atorvastatin group were higher than those in model group,with statistically significant differences(P<0.05).After 9 days,the levels of IL-6,TNF-α,TGF-βand IL-10 in the atorvastatin group and the model group were higher than those in the blank group,with statistically significant differences(P<0.05).The results of immunological function study showed that WBC,RBC and PLT in orvastatin group and model group were significantly reduced at 3 d compared with the blank group,with statistically significant differences(P<0.05).After 6 and 9 d,WBC,RBC and PLT in atorvastatin group and model group were lower than those in blank group,and WBC,RBC and PLT in atorvastatin group were lower than those in model group,with statistically significant differences(P<0.05).Conclusion:Atorvastatin can significantly improve the immune dysfunction and the expression of inflammatory cytokines in rats with Klebsiella pneumonia.