简介:Theworldhasbecomehighlydependentonreliablerefrigerationtechnology.Withoutit,ourfoodsupplywouldbestillseasonalandlimitedtolocallyproducednonperishableitems;comfortablelivingconditionsviaclimatecontrolwouldbeimpossible;andcertainmedicaladvancements,e.g.MRIdiagnostics,organtransplantation,organandtissuecryo-storage,andcryo-surgerywouldbeimpossible.
简介:Physicalandchemicalpropertiesofthemagneticnanoparticlescoatedwitholeatehavebeeninvestigatedbymeansoftransmissionelectronmicroscopy(TEM),thermogravimetricanalysis(TGA),Mossbauerspectroscopy,superconductingquantuminterferencedevice(SQUID)magnetometry,infraredspectra(IR)andthecontactangledevice.TheresultsshowthatdopedAlionsinFe3O4nanoparticlesarelocatedontheoctahedralsitesofthespinelstructure.Oleateiscoatedonthemagneticnanoparticleswithtwolayersbychemicalabsorbing,theouterlayercanbewashedaway.Thewettingofthesurfaceofmagneticnanoparticlescoatedwithmonolayerhasbeenchangedfromhydrophilicitytohydrophobicity,andthenanoparticlescanbedispersedverywellinsomeorganicsolutions.
简介:Ininversemicroemulsion,rareearthferrite/polyacrylamidemagneticmicrospherewerepreparedandtheirmagneticresponsibilitywerestudiedbymagneticbalance.Resultsindicatethatthemagneticresponsibilityofmicrosphererelatestomagneticmomentofrareearthion,anditcanbeimprovedbytheadditionofdysprosiumionofhighmagneticmoment.Dysprosiumcontenthasaneffectonmagneticresponsibilityofdysprosiumferrite/polyacrylamidemagneticmicrosphere.ThemicrospheredisplaysstrongmagneticresponsibilitywhenthemolarratioofDy3+/ironis0.20.
简介:Inrecentyears,pulsemagneticstimulationtechniquehasbeenpaidmoreandmoreattentionbythepeopleengagedinnoninvasivediagnosisandtherapywork.Comparedwithelectricstimulation,ithastheadvantagesofbeingnoninvasive,pain-lessandsafe,andhasbeenusedtoexamineandtreatdisordersofnervesystemsuc-cessfully.Applicationinotherfieldsisstillachallengetomanyresearchers.Wehave
简介:AnewcombinedFermi,betatron,andturbulentelectronaccelerationmechanismisproposedininteractionofmagneticislandsduringturbulentmagneticreconnectionevolutioninexplosiveastrophysicalphenomenaatlargetemporal-spatialscale(LTSTMR),theratioofobservedcurrentsheetsthicknesstoelectroncharacteristiclength,electronLarmorradiusforlow-βandelectroninertiallengthforhigh-β,isontheorderof10^10–10^11;theratioofobservedevolutiontimetoelectrongyroperiodisontheorderof10^7–10^9).Theoriginalcombinedaccelerationmodelisknowntobeoneofgreatestimportanceintheinteractionofmagneticislands;itassumesthatthecontinuouskinetic-dynamictemporal-spatialscaleevolutionoccursastwoseparateindependentprocesses.Inthispaper,wereconsiderthecombinedaccelerationmechanismbyintroducingakinetic-dynamic-hydrofull-coupledmodelinsteadoftheoriginalmicro-kineticormacro-dynamicmodel.Weinvestigatedifferentaccelerationmechanismsinthevicinityofneutralpointsinmagneticislandsevolution,fromthestageofshrinkandbreakupintosmallerislands(kineticscale),tothestageofcoalescenceandgrowthintolargerislands(dynamicscale),tothestagesofconstantandquasi-constant(contracting-expanding)islands(hydroscale).Asaresult,wegiveforthefirsttimetheaccelerationefficienciesofdifferenttypesofaccelerationmechanismsinmagneticislands’interactionsinsolaratmosphereLTSTMRactivities(pico-,10^–2–10^5m;nano-,10^5–10^6m;micro-,10^6–10^7m;macro-,10^7–10^8m;large-,10^8–10^9m).
简介:Anultrasensitivemagneticfieldsensorbasedonacompactin-fiberMach–Zehnderinterferometer(MZI)createdintwin-corefiber(TCF)isproposed,anditsperformanceisexperimentallydemonstrated.AsectionofTCFwassplicedbetweentwosectionsofstandardsingle-modefibers,andthenamicrochannelwasdrilledthroughonecoreoftheTCFbymeansoffemtosecondlasermicromachining.TheTCFwithonemicrochannelwasthenimmersedinawater-basedFe3O4magneticfluid(MF),formingadirectcomponentofthelightpropagationpath,andthensealedinacapillarytube,achievingamagneticsensingelement,whichmergestheadvantagesofanMZIwithanMF.Experimentswereconductedtoinvestigatethemagneticresponseoftheproposedsensor.Thedevelopedmagneticfieldsensorexhibitsalinearresponsewithinameasurementrangefrom5to9.5mTandanultrahighsensitivityof20.8nm/mT,which,toourbestknowledge,is2ordersofmagnitudegreaterthanotherpreviouslyreportedmagneticsensors.Theproposedsensorisexpectedtooffersignificantpotentialfordetectingweakmagneticfields.
简介:Exoticquantumspinliquid(QSL)statesandfractionalizedquasiparticlesinfrustratedmagnetsareofmuchcurrentinterestintheoreticalandexperimentalstudiesofquantummagnetism.Thekagome-latticeHeisenbergantiferromagnet(KAFM)providesapossiblerealizationofjustsuchnoveltopologicalstatesofmatter.ThekagomelatticeshowninFig.1isoneofelevenArchimedeanlatticesintwospatialdimensions,wherethewordkagomeitselfmeansuweavepattera"inJapanese.
简介:Magneticforcetransmissionofareciprocatingmotionisstudiedbytheoreticalanalysisandexperiment.Amathematicalmodelforcalculatingthemagneticforceisderivedusingthetheoryofequivalentmagneticcharges.Anexperimentalrigisconstructedtotestthetransmissionandthemodelisverifiedbyexperiment.Effectofthetransmissionparametersonthemagneticforceisanalyzedtheoreticallyfromthemodel,andcharacteristicofthetransmissionisstudiedexperimentally.Sincethetransmissioniswithoutdirectcontactbetweentwoelements,itissuitableforapplicationinanorganism.
简介:Magneticpropertiesandmagnetocaloriceffects(MCEs)ofthePrSicompoundwerestudied.ThePrSicompoundundergoesasecond-orderferromagnetic-to-paramagnetictransitionattheCurietemperatureofTC=52K.LargeMCEwithnomagnetichysteresislossisobservedaroundTC.Themaximumvaluesofmagneticentropychange(DS)arefoundtobe-8.6and-15.3Jkg-1K-1forthemagneticfieldchangesof0–2Tand0–5T,respectively.ThelargeDSwithnohysteresismakesPrSicompoundacompetitivecandidateformagneticrefrigerant.
简介:Energytransmissionefficiencyinthemagneticpulsegeneratorsvarieswithsaturatedtimeofmagneticswitch.Anoptimalmatchingtimeexistsanddependsonthecompressionratio,underwhich,theenergytransmissionefficiencycanreachapproximate100%.Theequationofrequiredmagneticcorevolumeisobtainedbytakenintoaccounttheoptimalmatchingmode.Itindicatesthatagreatreductiononthevolumeisfeasibleundertheoptimalmatchingmode.Thecircuitsimulationcode-PSPICEisalsointroducedtosimulatea3-stagemagneticpulsecompressor,andtheresultsareinaccordancewiththoseofequivalentcircuitanalyses.
简介:Anisotropicpowderwaspreparedwithprecursor(NdDy)-(FeCoNbCu)-Bsinteredmagnetsbyhydrogendecrepitation,desorption,andsubsequentannealingtreatment.Thehydrogendesorptionwasperformedinmagneticfieldsof0,1,3,and5T.Theorientationoftetragonalphasegrainsofthepowderwasevaluatedfromthehysteresisloopsmeasuredbyextractionmagnetometer.Residualhydrogencontentofthepowderwasevaluatedbythermal-magneticanalysis.ThepowderwithHcj,Br,and(BH)maxof1138kA·m-1,1.029T,and172.5kJ·m-3,respectively,wasachievedundertheconditionofthemagneticfieldof3T.Magneticpropertiesofthepowder,especially,theremanenceofthepowder,areenhanceduponmagneticfields,whichisduetobetterorientationofpowderparticlesandlessresidualhydrogeninthepowderresultedfromthemagneticfieldduringthehydrogendesorptionprocess.