简介:Theeffectofarcplasmaonelectrodeerosioninaliquidmetalcurrentlimiter(LMCL)isstudied.Basedonasimplifiedtwo-dimensionalmagnetohydrodynamicmodel,theelongatedGaInSnmetalvaporarcanditscontractionprocessinaliquidmetalcurrentlimiteraresimulated.Thedistributionsoftemperature,pressureandvelocityofthearcplasmaarecalculated.Thesimulationresultsindicatethattheelectrodeerosionismainlycausedbytwohightemperaturegasjetflowsarisingfromthepressuregradient,whichisaresultofthenon-uniformarctemperaturedistribution.Thegasflows,whichactasjetsontotheelectrodesurface,leadtotheevaporationoftheelectrodematerialformthesurface.Aredesignstructureoftheelectrodeisproposedandimplementedaccordingtotheanalysis,whichgreatlyincreasedtheservicelifeoftheelectrode.
简介:SpectroscopicmethodsareusedtoinvestigatecoordinationstructureofN-picolylpolyurethanetransitionmetalcomplexes(PUPYM,M=Co^2+andNi^2+).Geometricalarrangementofligandsinfirst-shellcoordinationsphereofmetalionsispostulatedtobetetrahedralCoL2Cl2andoctahedralNiL2-Cl2Z2.whereListhepicolylgroupandZisahydrate.FromextendedX-rayabsorptionfinestructure(EXAFS)analysis,bondlengthsformetal-chlorineandmetal-ligandofPUPYMaresimilartothoseofsmallmolecularweighttransitionmetalcomplexes.Atwo-phasemodelofPUPYMwhichbestdescribestheexperimentaldataofDMTAandSAXS.isproposed.Onemicrophaseistheharddomainofselfsegregatedhaedsegmentsbroughtaboutbymetal-ligandinteraction.andtheotherphaseisthematrixofsoftsegments.Transitionmetalion-ligandmoietiesandtheirinteractionsdominatethemacroscopicthermalbehaviorofPUPYM.Theligandfieldstabilizationenergydifference(ΔLFSE)betweenmteald-electronsincomplexeswithtwopicolylligandsinthecoordinationsphereofmetalionsandcomplexesmaintainingonepicolylligandascoordinationpendentgroupiscalculatedonthebasisofobservedcoordinationstructure,anditrepresentstheenergysuppliedtosplitcoordinationcross-links.ΔLFSEofpolyurethanenickel(II)complexislargerthanthatofthecobalt(II)complex,Sincethemobilityofhardsegmentsisininverseproportiontothestrengthofcoordinationcross-links.ahigherα-transitiontemperatureofPUPYNi^2+withrespecttoPUPYCo^2+isfoundasexpected.
简介:Inthisstudy,SiO_xfilmsweredepositedbyadielectricbarrierdischarge(DBD)plasmagunatanatmosphericpressure.TherelationshipofthefilmstructureswithplasmapowerswasinvestigatedbyFouriertransforminfraredspectroscopy(FTIR),andscanningelectronmicroscope(SEM).Itwasshownthatanuniformandcross-linkingstructurefilmwasformedbytheDBDgun.Asanapplication,theSiO_xfilmsweredepositedonacarbonsteelsurfacefortheanti-corrosionpurpose.Theexperimentwascarriedoutina0.1MNaC1solution.Itwasfoundthataverygoodanti-corrosivepropertywasobtained,i.e.,thecorrosionratewasdecreasedc.a.15timesin5%NaClsolutioncomparedtothenon-SiO_xcoatedsteel,asdetectedbythepotentiodynamicpolarizationmeasurement.
简介:Itwasrecentlysuggestedthattheperiodicandfractalprecipitaionofcalciumsaltsandproteinsincholesterolgallstonesiscloselyrelatedtotheprocessofstoneformation.Thepresentstudyistomimictheprocessofgallstonegrowthinvitro.Wedemonstrateforthefirsttimethatathree-dimensionalstructureofperiodicrings(Liesegangring)and/orfractalpatternscanbeproducedbymetalionanddeoxycholateprecipitaitonwhicharesimilartogallstones.Precipitationinaperiodicpatternoccursmoreoftenthaninafractalstructure,UsingX-raydiffraction.polarizedlightmicroscope,Fouriertransform-infrared(FT-IR),andextendedX-rayabsorptionfinestructure(EXAFS),westudiedthepatternformationmechanismsofbothtypesofstructure.Theresultsindicatethattherateofnucleationinthecrystalgrowthisacrucialelementofaffectthepatternformation.Thepatternselectionbetweenperiodicandfractaltypedependsonthecrystalgrowthspeedandtherateofnucleation.