Interfacial reaction between AZ91D magnesium alloy melt and mild steel under high temperature

The metallurgical quality control of magnesium(Mg)and Mg alloys in melting process is required to ensure a satisfied mechanical and corrosion performance,while the typical used steel crucible introduces impurities and interfacial interaction during melting process.Therefore,a systematic study about impurities diffusion and interfacial interaction between molten Mg and steel is necessary.In the present study,the interfacial reaction between molten AZ91D Mg alloy and mild steel during melting process was investigated with the melting temperatures of 700℃,750℃ and 800℃.The results show that Al(Fe,Mn)intermetallic layer is the intermetallic primarily formed at the interfaces of AZ91D melt and mild steel.Meanwhile,Al_(8)(Mn,Fe)5is indexed between Al(Fe,Mn)and AZ91D.AlFe_(3)C appears between the mild steel and Al(Fe,Mn)at 700℃ and 750℃,but absent at 800℃ due to the increased solubility of carbon in Mg matrix.It is found that the growth of the intermetallic layer is controlled by diffusion mechanism,and Al and Mn are the dominant diffusing species in the whole interfacial reaction process.By measuring the thickness of different layers,the growth constant was calculated.It increases from 1.89(±0.03)×10^(-12)m^(2)·s^(-1)at 700℃ to 3.05(±0.05)×10^(-12)m^(2)·s^(-1)at 750℃,and 5.18(±0.05)×10^(-12)m^(2)·s^(-1)at 800℃.Meanwhile,the content of Fe is linearly increased in AZ91D with the increase of holding time at 700℃ and 750℃,while it shows a significantly increment after holding for 8 h at 800℃,indicating holding temperature is more crucial to determine the Fe content of AZ91D than holding time.

胃癌根治术后并发肺部感染危险因素的Meta分析

目的系统评价胃癌根治术后患者发生肺部感染的危险因素。方法检索PubMed、Web of Science、Embase、中国知网、万方数据库、维普数据库和中国生物医学文献数据库,检索时间为建库至2021年12月17日。由2名研究者独立筛选文献、提取资料,采用NOS量表进行质量评价,应用RevMan 5.4、Stata15.1软件进行Meta分析。结果共纳入23项研究,总样本量为10696例。Meta分析结果显示,胃癌根治术后并发肺部感染的危险因素包括高龄[OR=2.67,95%CI(1.90,3.74),P<0.001)]、吸烟史[OR=3.09,95%CI(2.44,3.92),P<0.001]、糖尿病[OR=4.48,95%CI(1.91,10.53),P<0.001]、围手术期输血[OR=4.49,95%CI(2.65,7.61),P<0.001]、手术时间长[OR=2.19,95%CI(1.19,4.03),P=0.01]、术中出血[OR=2.46,95%CI(1.62,3.74),P<0.001]、留置胃管时间长[OR=4.03,95%CI(3.74,4.33),P<0.001]、营养风险[OR=1.82,95%CI(1.43,2.33),P<0.001]、肺部疾病史[OR=3.09,95%CI(1.89,5.05),P<0.001]、手术方式[OR=3.33,95%CI(2.93,3.79),P<0.001]、白蛋白≤30 g/L[OR=1.82,95%CI(1.39,2.37),P<0.001]、TNM分期[OR=2.18,95%CI(1.75,2.72),P<0.001]、引流管放置时间长[OR=1.48,95%CI(1.22,1.79),P<0.001]、合并基础疾病[OR=2.48,95%CI(1.83,3.35),P<0.001]、高血压史[OR=2.59,95%CI(1.48,4.52),P<0.001]、低蛋白血症[OR=3.02,95%CI(2.87,3.18),P<0.001]、伤口疼痛[OR=3.42,95%CI(1.96,5.99),P<0.001]、肺功能不全[OR=2.74,95%CI(1.84,4.09),P<0.001];胃癌根治术后并发肺部感染的保护因素为血红蛋白≥110 mg/L[OR=0.67,95%CI(0.56,0.79),P<0.001]和第1秒用力呼气容积>2 L[OR=0.22,95%CI(0.12,0.40),P<0.001]。结论高龄、吸烟史、围手术期输血、糖尿病、高血压、肺部疾病史、手术时间长、术中出血、留置胃管时间长和营养风险等是胃癌根治术后并发肺部感染的危险因素,但受纳入研究质量和数量限制,未来还需开展更多高质量的研究予以验证。

Discharge properties of Mg-Sn-Y alloys as anodes for Mg-air batteries

Mg-Sn-Y alloys with different Sn contents(wt%)were assessed as anode candidates for Mg-air batteries.The relationship between microstructure(including the second phase,grain size,and texture)and discharge properties of the Mg-Sn-Y alloys was examined using microstructure observation,electrochemical measurements,and galvanostatic discharge tests.The Mg-0.7Sn-1.4Y alloy had a high steady discharge voltage of 1.5225 V and a high anodic efficiency of 46.6% at 2.5 mA·cm^(-2).These good properties were related to its microstructure:small grain size of 3.8μm,uniform distribution of small second phase particles of 0.6μm,and a high content(vol%)of(1120)/(1010)orientated grains.The scanning Kelvin probe force microscopy(SKPFM)indicated that the Sn_(3)Y_(5) and MgSnY phases were effective cathodes causing micro-galvanic corrosion which promoted the dissolution of Mg matrix during the discharge process.