简介：Objective:Tostudytheinfluenceofstress-relaxationplateondisorganizationandrepairofthecortexbeneaththeplate.Methods:Awashermadeofviscoelasticpolyethylenewasplacedbetweenthescrewandthescrewholeofconventionalstainlessrigidplate(RP)toproduceastressrelaxationplate(SRP).BothSRPandRPwereappliedtoosteotomizedtibiain48NewZealandrabbits.HealingprocessofthefracturewitheitherSRPorRPfixation(control)wascomparativelystudiedwithpolarizedlightmicroscopy,insituhybridizationofcollagenmRNAandimmunohistochemicaltechniquefrom2to36weekspostoperatively.Results:ThestudyofplatedboneremodelingshowedthatthedegreeofcortexosteoporosisbeneaththeplatewassimilarbetweentheSRPandRPgroupwithin12weekspostoperatively.Incomparison,thedisorganizationofbonestructureinSRPgrouphappenedlaterandmilderthanthatofRPgroup,andtherepairprocessbeganat12weeksafterimplantation.Asaconsequence,theabsorptioncavitiesbecamesmallerandthestructureofcollagenfibersbecamewellorientedalongwiththesechangesbypolarizedlightmicroscopy.Inadditiontothese,theinsituhybridizationanalysisofcollagengenesandtheimmunohistochemicalstudyoftypeI,Ⅲcollagenat8to12weeksafterimplantation.fromthistimeon,thechangesabovebecamemoreevidentsignificantlybeforemostofcavitieswererepairedby36weeks.IncontrasttothechangesintheSRPgroup,noexpressionandsynthesisofanykindofcollagencouldbeobservedduring12to36weeksafterimplantationinRPgroup.Conclusions:Withoutremovaloftheboneplate,theSRPfixationnotonlyreducesthedegreeofplatedboneosteoporosis,butalsomakesthedisorganizedbonestructurerestoredtonormalintermsoftheexpressionandsynthesisoftypeIcollagenmRNAofosteoblastslyingonthesurfaceofabsorptioncavities.

简介：Aim:Tostudythestrengthandmicrostructureoftrace-Ti-bearingstracturesteel.MaterialsandMethods:ThestrengthandmicrostructureofthetraceTibearingstructuresteelwerestudiedbytwokindsofcontrolledcoolingsimulationtestingresultsinthefirststagecoolingandthelaststagecoolingafterhotpressdeformationinthetrace-Ti-bearingstructuresteel.Results:Itshowedthattheferritegrainsize,therelativecontributionoftheinvolvedstrengthandthemechanicalstrengthwereinfluencedmoreorlessbydifferentcoolingrates.Boththerefinementofferritegrainandtheincreaseofmechanicalstrengthcouldbeobtainedbytheproperdecreaseofwatercoolinginterruptiontemperature(WTI)andcoilingtemperature(CT)inthefirststagecoolingortheproperincreaseofwatercoolingbeginningtemperature(WTB)andproperdecreaseofcoilingtemperature(CT)inthelaststagecooling.Conclusion:Thestrength,theferritegrainrefinementandtheyieldtensileratiointhefirststagecoolingprocessaremuchbetterthanthoseinthelaststagecoolingprocess.