采用高压固溶制备具有均匀腐蚀行为的高强度抗菌Zn-4Ag-Mn合金

采用高压固溶(HPS)法制备Zn-4Ag-Mn合金,获得高强度、可均匀降解、抗菌的植入材料。显微组织表征表明,HPS处理使Zn-4Ag-Mn合金晶粒比铸态(AC)合金的细化57.9%,其第二相平均尺寸减小到10.2μm。压缩、维氏硬度和磨损摩擦试验表明,HPS合金具有较高的力学性能,抗压屈服强度为333.5MPa,维氏硬度为Hv 89.5。电化学腐蚀和浸泡腐蚀试验表明,HPS处理优化合金的耐蚀性,使其腐蚀均匀。此外。经抗菌实验测试,HPS处理的Zn-4Ag-Mn合金具有优异的抗菌性能,抗菌率为71.6%。这些结果表明,HPS处理的Zn-4Ag-Mn是一种很有前途的生物可降解植入材料。

含碳FeCoCrNiMn高熵合金的异质显微组织和力学性能

利用可控热机械处理工艺,在含0.5%C(摩尔分数)的FeCoCrNiMn高熵合金中获得具有纳米析出相和双峰晶粒尺寸分布的异质显微组织。粗大的M23C6碳化物倾向于在细晶粒的晶界处形成。与具有均匀显微组织的样品相比,异质结构FeCoCrNiMn−0.5%C(摩尔分数)高熵合金具有相似的平均晶粒尺寸(约4.8μm)。然而,它具有晶粒双峰结构且粒径<3μm的细晶粒的体积分数更高,从而使屈服强度从552 MPa提高到632 MPa。具有异质结构的样品在不同的区域呈现不同的力学性能和变形显微组织,导致在拉伸变形过程中产生明显的应变局域化和高密度的几何必要位错。这些变形特征有利于提高应变硬化能力,从而促进强度−塑性的协同作用。

Effect of cross wedge rolling on the microstructure of GH4169 alloy

The metal microstructure during the hot forming process has a significant effect on the mechanical properties of final products. To study the microstructural evolution of the cross wedge rolling （CWR） process, the microstructural model of GH4169 alloy was programmed into the user subroutine of DEFORM-3D by FORTRAN. Then, a coupled thermo-mechanical and microstructural simulation was performed under different conditions of CWR, such as area reduction, rolling temperature, and roll speed. Comparing experimental data with simulation results, the difference in average grain size is from 11.2% to 33.4% so it is verified that the mierostructural model of GH4169 alloy is reliable and accurate. The fine grain of about 12-15 p.m could be obtained by the CWR process, and the grain distribution is very homogeneous. For the symmetry plane, increasing the area reduction is helpful to refine the grain and the value should be around 61%. Moreover, when the roiling temperature changes from 1000 to 1100℃ and the roll speed from 6 to 10 r.min-1, the grain size of the rolled piece decreases first and then increases. The temperature may be better to choose the value around 1050℃ and the speed less than 10 r-min-1.

Influence of process parameters on properties of AA6082 in hot forming process

The influences of process parameters on mechanical properties of AA6082in the hot forming and cold-die quenching(HFQ)process were analysed experimentally.Transmission electron microscopy was used to observe the precipitate distribution and to thus clarify strengthening mechanism.A new model was established to describe the strengthening of AA6082by HFQ process in this novel forming technique.The material constants in the model were determined using a genetic algorithm tool.This strengthening model for AA6082can precisely describe the relationship between the strengths of formed workpieces and process parameters.The predicted results agree well with the experimental ones.The Pearson correlation coefficient,average absolute relative error,and root-mean-square error between the calculated and experimental hardness values are0.99402,2.0054%,and2.045,respectively.The model is further developed into an FE code ABAQUS via VUMAT to predict the mechanical property variation of a hot-stamped cup in various ageing conditions.

Curcumin Recovers Intracellular Lipid Droplet Formation Through Increasing Perilipin 5 Gene Expression in Activated Hepatic Stellate Cells In Vitro

The activation of hepatic stellate cells(HSCs)is a major event during hepatic fibrogenesis.Restoration of intracellular lipid droplet(LD)formation turns the activated HSC back to a quiescent state.Our previous studies have shown that curcumin suppresses HSC activation through increasing peroxisome proliferator-activated receptor,gamma(PPARγ)and 5′adenosine monophosphate-activated protein kinase(AMPK)activities.This study aims at evaluating the effect of curcumin on lipid accumulation in HSCs and hepatocytes,and further elucidating the underlying mechanisms.Now we showed that curcumin increased LD formation in activated HSCs and stimulated the expression of sterol regulatory element-binding protein and fatty acid synthase,and reduced the expression of adipose triglyceride lipase.Exogenous perilin5 expression in primary HSCs promoted LD formation.Perilipin 5 siRNA eliminated curcumin-induced LD formation in HSCs.These results suggest that curcumin recovers LD formation and lipid accumulation in activated HSCs by increasing perilipin 5 gene expression.Furthermore,inhibition of AMPK or PPARy activity blocked curcumin's effect on Plin5 gene expression and LD formation.Our results provide a novel evidence in vitro for curcumin as a safe,effective candidate to treat liver fibrosis.

Ductile fracture behavior of TA15 titanium alloy at elevated temperatures

To better understand the fracture behavior of TA15 titanium alloy during hot forming, three groups of experiments were conducted to investigate the influence of deformation temperature, strain rate, initial microstructure, and stress triaxiality on the fracture behavior of TA15 titanium alloy. The microstructure and fracture surface of the alloy were observed by scanning electronic microscopy to analyze the potential fracture mechanisms under the experimental deformation conditions. The experimental results indicate that the fracture strain increases with increasing deformation temperature, decreasing strain rate, and decreasing stress triaxiality. Fracture is mainly caused by the nucleation, growth, and coalescence of microvoids because of the breakdown of compatibility requirements at the α/β interface. In the equiaxed microstructure, the fracture strain decreases with decreasing volume fraction of the primary α-phase(αp) and increasing α/β-interface length. In the bimodal microstructure, the fracture strain is mainly affected by α-lamella width.

Systematic Review and Meta-analysis of Shenfu Injection on Treating Acute Exacerbation of Chronic Obstructive Pulmonary Disease

The objective of the study was to systematically evaluate the efficacy and safety of Shenfu injection in the treatment of patients with acute exacerbation of chronic obstructive pulmonary disease(AECOPD).A total of 15 randomized controlled trials involving 1198 patients were included.The results of meta-analysis showed that compared with the control group,the experimental group can improve the total clinical effective rate in AECOPD patients(relative risk=1.15,95%confidence interval[CI][1.09,1.21],P<0.00001),improve the pulmonary function levels:forced expiratory volume in one second(FEV1)(standardized mean difference=1.88,95%CI[0.89,2.88],P=0.0002)and the FEV1/forced vital capacity(FVC)ratio(FEV1/FVC)(mean difference[MD]=3.96,95%CI[2.74,5.19],P<0.00001);improve the arterial blood oxygen partial pressure(MD=6.03,95%CI[4.58,7.48],P<0.00001),and reduce the arterial blood partial pressure of carbon dioxide(MD=-4.59,95%CI[-6.91,-2.26],P=0.00001),and the white blood cell count in pulmonary infection may be improved(MD=-1.16,95%CI[-1.63,-0.68],P<0.00001).The study showed that the efficacy of experimental group in the treatment of AECOPD is better than control group.Due to the limitation of the number and quality of included studies,this conclusion needs more high quality studies to confirm.