简介:采用Gleeble热模拟方法研究Mg-6Zn-1Al-0.3Mn变形镁合金在温度为200-400°C,应变速率为0.01-7s-1条件下的热压缩变形行为。结果表明,变形温度和应变速率显著影响其热变形行为。通过计算获得了热变形激活能及应力指数分别为Q=166kJ/mol,n=5.99,且其本构方程为ε&=3.16×1013[sinh(0.010σ)]5.99exp[-1.66×105/(RT)]。热压缩显微组织观察表明:在应变速率为0.01-1s-1的条件下,在250°C热压缩变形时初始晶粒晶界及孪晶处发生了部分动态再结晶,而在高温(350-400°C)条件下,发生了完全动态再结晶且再结晶晶粒尺寸随着应变速率的增加而减小。获得的较优的变形条件为温度330-400°C、应变速率为0.01-0.03s-1以及350°C、应变速率为1s-1。
简介:目的比较40mg和10mg阿托伐他汀对ACS合并糖尿病患者糖代谢基因Akt/Glut4的表达足否存在差异。方法80例ACS合并糖尿病患者随机分为阿托伐他汀40mg和10mg治疗组,于治疗前、治疗后1个月、3个月分别检测空腹血糖(FBG)、血脂等,并应用ELISA双抗体央心法测定血清中Akt/Glut4表达。结果阿托伐他汀10mg组,于治疗前、治疗后1个月及3个月AkI和Glut4表达水平筹异均尤统计学意义;40mg治疗组,治疗后3个月与治疗前比较,Akt和Glut4的表达均降低,有显著的统计学差异(P=0.008和P=0.033)。而对于FBG的影响:10rag组及40rag组治疗后3个月较治疗前有升高倾向,但差异无统计学意义(P值分别为0.852和0.650)。结论阿托伐他汀40mg的治疗剂量可以下调糖代谢基因Akt/Glut4在ACS合并糖尿病患者中的表达。40mg阿托伐他汀对空腹血糖的影响不鼎著.。
简介:采用真空气氛保护金属型制备Mg-4Zn-1Ca三元合金,利用光学显微镜、扫描电子显微镜、浸泡腐蚀失重试验研究了铸态Mg-4Zn-1Ca合金在SBF模拟体液中的腐蚀行为及腐蚀性能。结果表明,Mg-4Zn-1Ca合金的腐蚀速率随着时间的延长而降低,并观察到在60min时氧化膜丧失保护能力。经过5h浸泡后,铸态合金的平均腐蚀速率从最高的10.91mm/a下降到了4.447mm/a。
简介:IPv4的地址空间已经耗尽,但目前绝大多数的应用都是基于IPv4协议的,从IPv4向IPv6的过渡将是一个相当长的过程.在过渡期间,必须要实现两者之间的平稳过渡.目前解决过渡问题的基本技术主要有双协议栈,隧道和网络地址转换——协议转换.在不同环境下,要因地制宜,选择出合理的转换机制,成功地完成过渡.
简介:Becauseofrapiddevelopmentinnetworktechnology,Internetusagehasbecomewidespread.Itallowsuserswithsensingdevicestoobtainmedicaldataforhealthcare,suchasphysiologicalsignals,voice,andvideostreamsfromtelemedicinesystems,andtosendthehealthcaredatatoback-enddatabasesystems,creatingaubiquitoushealthcareenvironment.However,thisenvironmentrequiresawidespreadandsuitablenetwork.IPv6(Internetprotocolversion6)isthenext-generationInternetprotocolthatwillbetheprotocoloffuturenetworks;itimprovesmanyshortcomingsofIPv4.Inthispaper,weproposeanIPv6/IPv4U-home-caretestsystemandanalyzethenetwork’sparametersthoughaseriesoftestsbyadjustingnetworkparameterstofindtheoptimaldesignforapplicationsintheIPv6/IPv4U-home-careservicesoastoassuregoodperformanceandhighquality.
简介:Hydrogen,asatemporaryelementintitaniumalloys,isverygoodincontrollingmicrostructure.ThemicrostructureandphasetransformationofTi6A14ValloyareaffectedbytheamountofTiH,addedintothemeltofTi6A14Valloyduringtheinductionskullmelting(ISM)process.Thisprocess,calledmelthydrogenation,wasstudiedinthispaperthroughtheuseofopticalmicroscopy,scanningelectronmicroscopy(SEM)andtransmissionelectronmicroscopy(TEM).Theresultsareasfollows:aftermelthydrogenation,boththesolidificationmacrostructureandmicrostructureofTi6A14Valloyarerefined;theαphaseprecipitatesinalamellarformwiththeresidualβphasefromthegrainboundaries;δ-hydridesprecipitateduringthesolidificationprocessasaresultoftheexistenceofhydrogen.TheSphasewithanF.C.C.structurecanbeobservedbyTEMintheαphaselaminaeofspecimenswith1.25%TiH2.Inaddition,thedependenceofthemicrohardnessofspecimensontheweightpercentageofTiH,addedtothemeltduringtheISMprocesswasalsostudied.
简介:采用光学显微镜和场发射扫描电镜,研究超声波对原位Mg2Si/Al复合材料中初生Mg2Si形态的影响。研究结果表明:超声波处理使初生Mg2Si的晶粒尺寸从150μm降低到20μm,初生Mg2Si形态发生改变。在二维形貌中,未实施超声波振动处理的初生Mg2Si晶粒生长为含有空腔的粗大颗粒,共晶组织生长于其中,相应的三维形态为含有漏斗状空腔的八面体和十四面体。超声波处理后的初生Mg2Si晶粒变成细小、实心三维形态的颗粒,颗粒棱角已发生钝化效应。