简介：ConstantloadtestsinNS4solutionpurgedwithN2-5%CO2gasmixturewereconductedonAmericanPetroleumInstitute(API)X80pipelinesteelappliedinthe2ndWest-EastGasPipelineprojectwithandwithoutpreload.TheresultsshowthatcrackscouldinitiateandpropagateinX80pipelinesteelinnear-neutralpHenvironmentunderaconstantloadcondition.Thelifeofcrackinitiationandpropagationincreasedwithdecreasingappliedstress.Preloaddidnotchangeitscorrosionbehaviorobviously.However,preloadreducedthetimeforcrackinitiation.

简介：Compositenanofibermembranesbasedonbiodegradablepoly(lacticacid)(PLA)andcellulosenanofibrils(CNF)wereproducedviaelectrospinning.TheinfluenceofCNFcontentonthemorphology,thermalproperties,andmechanicalpropertiesofPLA/CNFcompositenanofibermembraneswerecharacterizedbyfieldscanningelectronmicroscopy(FE-SEM),differentialscanningcalorimetry(DSC),thermogravimetricanalysis(TGA),anddynamicmechanicalanalysis(DMA),respectively.TheresultsshowthatthePLA/CNFcompositenanofiberswithsmooth,free-beadsurfacecanbesuccessfullyfabricatedwithvariousCNFcontents.TheintroductionofCNFisaneffectiveapproachtoimprovethecrystallineability,thermalstabilityandmechanicalpropertiesforPLA/CNFcompositefibers.TheYoung’smoduliandtensilestrengthofthePLA/CNFcompositenanofiberreach106.6MPaand2.7MPawhentheCNFcontentis3%,respectively,whichareonetimeshigherand1.5timesthanthoseofpurePLAnanofiber.Additionally,thewatercontactangleofPLA/CNFcompositenanofibermembranesdecreaseswiththeincreaseoftheCNFloading,resultingintheenhancementoftheirhydrophilicity.

简介：Thesol-gelprocessofcitricacidchelatingwithmetalcationsforthesynthesisofnormalspinelLiMn2O4andthereactionmechanismwereinvestigatedbymeansofXRD,IR,TG-DTA,andSEM.Theresultsshowthatatthebeginninglithiumcitrateandchelatecompoundofcitricacidwithmanganeseionsformed,andthenwithheatingtheesterificationandcondensationreactionsoccuredbetweenthemandglycol.TheproductsobtainedarepolymersinwhichmetalcationsaredistributedhomogeneouslyonatomicscalethatensurehighreactivitytocationsofLi+andMn2+.Firingthegelpreparedbythisprocess,thelatticediffusionsofsolidreactantionscausedbynon-homogeneityofreactantsareeliminatedandavoided.At400℃phase-pureLiMn2O4withnanometerscalecrystallizationhavingprecisestoichiometryandperfectcrystallizationcanbeobtained.Themodelofchelatecoordinateofdouble-moleculebetweencitricacidandMn2+inthegelnetworkisproposed.ItisimportantforexplainingthedispersionstateofMn2+andtheformationprocessofgelbythismodel.

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