简介：Oxidationprocessoflanthanumhexaboride(LaB6)ceramicpowderwasinvestigated.TheLaB6powdersampleswereheatedcontinuallyfromroomtemperatureto1473Kataheatingrateof10K/minbydifferentialscanningcalorimetry.Theoxidationtestswereconductedatdifferentexposuretemperatures.ThephasesandmorphologiesofthesamplesbeforeandafterexposurewereanalyzedbyXRDandSEM.Itwaspointedoutthatbefore1273K,LaB6hashighoxidationresistantability,whichwasduetothattheoxidelayerhinderstheoxygendiffusionfromoutertothesurfaceofLaB6grains.Theoxidelayerwascomposedofthetransitionphases,whichwerecomposedofLa2O3andB2O3formedfromtheinitialoxidation;whentheoxidationtemperatureexceeded1273K,protectivelayerwasdestroyedduetothevaporizationofliquidB2O3.BasedontheresultsofX-raydiffractionanalysis,oxidationprocessofLaB6ceramicpowdercanbedescribedasfollows:Before1273K,lanthanumborate，La(BO2)3wasformedonthesurfaceofsamples,thenlanthanumoxide(La2O3)andboronoxide(B2O3)werepresentonthesurfaceofsamplesoxidizedwhenthetemperaturereachedto1473K.

简介：YoungWistarratsweredividedintosixgroups,theexperimentalgroupsweregivenLa(NO3)3atdoseof20,10,2,0.2,0.1mg*kg-1andthecontrolgroupwasgivenphysiologicalsalinerespectivelyforsixmonths.Theanimalswereweighedandtheratiosofthelivertobodyweightwerecounted.Pathologicalchangesofliverwereobservedbylightmicroscopeandtransmissionelectronmicroscope.Glutamic-oxalacetictransaminase(GOT),glutamic-pyruvictransaminase(GPT),gamma-glutamyltransferase(γ-GT)andalklinephosphatase(ALP)intheserumweremeasured.Theresultsindicatethatthebodyweightofanimalsgainesslowlyinthegroupof20mg*kg-1La(NO3)3,butitgainedquicklyintheratsfedwith0.1mg*kg-1La(NO3)3.Biochemicalindexeshavenoabnormalchanges.Inthegroupof20mg*kg-1La(NO3)3,therewerelipiddropletsanddecreaseofglycogeninthehepatocytes,densermatrixofthemitochondria,deformationofthenucleiofsomehepatocytestodifferentdegreeandinfiltrationofinflammatorycellsatportalarea.ThemorethedoseofLa(NO3)3weregiventotherats,themorethenumberofbodiescontaininghighlyelectronicdensegravel-likegranulesandthesecondarylysosomeswithdensebodies.Theratsfedwith20mg*kg-1La(NO3)3forsixmonthsshowsinjuriouseffectsonthehepatocytes.

简介：TheeffectsofLaonsomehydrolyticenzymeactivitiesinredsoilwerestudiedinincubationandpetcultureexperiments.Intheincubationexperiment,Laslightlystimulatestheactivitiesofureaseandacidicphosphataseinsoilandstronglystimulatessucraseactivityinsoil.Inthepetcultureexperiment,Lastimulatestheactivitiesofurease,acidicphosphataseandsucrasetodifferentdegrees.Thestimulativeeffectsofrareearthelements(REE)onhydrolyticenzymeactivitiesinsoilmayresultinincreasingyieldofeivps.

简介：TheinfluencesofMediumpH,sorptiontemperature,sorptiontime,etc.onthesorptioncapacityofmacroporousphosphonicacidresinforLa^3+weredetermined.Thesorptionrateconstantwask298=7.64×10^-5s^-1.ThecomplexratioofphosphonicgroupsoftheresintoLa^3+was3:1.Thebasicsorptionparametersweredetermined.ThesorptionmechanismofmacroporousphosphonicacidresinforLa^3+wasexaminedbychemicalanalysisandIR-spectrometry.

简介：ＳｔｕｄｉｅｓｏｎＥｌｅｃｔｒｏｌｙｔｉｃＣｏｄｅｐｏｓｉｔｉｏｎｏｆＬａｎｔｈａｎｕｍ－ＣｏｂａｌｔｉｎＵｒｅａＭｅｌｔＱｉｕＫａｉｒｏｎｇ（丘开容），ＹａｎｇＱｉｑｉｎ（杨绮琴）（ＤｅｐａｒｔｍｅｎｔｏｆＣｈｅｍｉｓｔｒｙ，ＺｈｏｎｇｓｈａｎＵｎ...

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简介：Theeffectoflanthanumiononmembranepermeabilityofcornrootsegmentisstudied.ResultsshowsthattreatmentoftherootsegmentswithLaCl3·7H2Ocandecreasetheionleakageoftheroottissue.Theleakagedecreaseshyincreasingtheconcentrationoflanthanum,andtheconcentrationhasnofurtherdependenceonionleakagesabove25μmol/L.Aftertreatingtheroottissueforonehourwithlanthanumion,theamountofleak-agehaslineardependenceontimewithinthefirst2handaftertwohourstheleakageincreases.Theionleakageofthetissuedependesonthetimeoflanthanumtreatment.Whenthedurationoftreatmentisprolonged,theleakagedecreasesrapidlyandtheleakagereachesaminimumat30minutes.Otherrareearthelementscanalsodecreaseionleakage.Thereisnosignificantdifferenceintheionleakageamongtheseelements.

简介：TheelectrochemicalbehaviourofcopperelectrodeinmoltenNaCl-KCl-LaCl3hasbeeninvestigated.TheLa-CualloyisformedatfirstandthenthemetalliclanthanumisdepositedwhentheLa3+isreducedonthecopperelectrode.ThetechnologicalconditionsofpreparingLa-Cualloybyconsumablecathodehavebeendis-cussed.TheLa-Cualloycontainedlanthanumover90wt%wasobtained.ThecompositionofalloywasLaCu2andLa.Thecurrentefficiencywas85%andtherecoveryoflanthanumwasnear90%.

简介：Theheatcapacitiesofthetwocomplexes,[La2(Gly)6(H2O)4]·(ClO4)6and[Ho2(Gly)6(H2O)4](ClO4)6·2H2O(Gly=glycine),weremeasuredbyadiabaticcalorimetryinthetemperaturerangeform78to375K.Asolid-solidphasetransitionwasfoundbetween322.87and342.29Kfor[Ho2(Gly)6(H2O)4](ClO4)6·2H2O,andthepeaktemperature,theenthalpyandtehentropyofthetransitionwereobtainedtobe330.94K,11.65kJ·mol^-1and35.20J·K^-1·mol^-1,respectively.Noindicationofanyphaestransitionorthermalanomalywasobservedfor[La2(gly)6(H2O)4](ClO4)6,Thermalstabilitiesofthetwocomplexeswereinvestigatedbythermogravimetryinthetemperaturerangeof40-800℃.thepossiblemechanismsforthethermaldecompositionswereproosedaccordingtotheTGandDTGcurves.

简介：ThroughapotculturelanthanumnitratewasappliedtomaizeseedlingsgrowninaredloamysoiltoinvestigatethephysiologicalandtoxiceffectsofaddedLaonthegrowthofcropseedlingsandLabioaccumulationtohelpunderstandtheenvironmentalchemistrybehaviorsofrareearthelementasfertilizersinsoils.Comparedtothecontrol,LaconcentrationsinshootsandespeciallyinrootsofmaizeseedlingsincreasedwithanincreaseofLainthesoil.Also,withaddedconcentrationsofLa≥0.75gLakg-1soiland≥0.05gLakg-1soil,thedryweightofshootsandrootsofmaizeseedlingswassignificantlyreduced(P≤0.05),respectively,comparedwiththecontrol.Additionally,La≥0.5gkg-1inthesoilsignificantlyinhibited(P≤0.05)primaryrootelongation.RootsweremoresensitivetoLastressthanshootsandthuscouldbeusedasabiomarkertoLastress.Overall,intheredloamysoilstudied,LahadnosignificantbeneficialeffectsonthegrowthofmaizeattheaddedLalevelsabove0.1gkg-1soil.

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简介：Studieshavebeencarriedoutontheeffectoflanthanum-aminoacidcomplexesonembryodevelopmentandnaupliusgrowthofPenaeuschinensis.Theexperimentalresultsindicatethat:(1)Theoptimumconcentrationsoflanthanum-prolineandLanthanumphenylalanineforthedevelopmentofeggsinmonocellanddicellstagesare1.50～4.00mg/Land0.50～3.00mg/L,respectively,theegghatchingratesbeingraisedby21.0～46.0%and23.0～42.8%(P＜0.05)respectively.(2)Theoptimumconcentrationsoflanthanum-prolinecomplexandLanthanum-phenylalaninecomplexforthegrowthofnaupliiare1.50～4.00mg/Land0.50～3.00mg/L,themetamorphosisratefromnaupliustoprotozoeabeingraisedby16.4～27.5%and20.4～26.7%(P＜0.05)respectively.(3)Thepositiveeffectoflanthanum-aminoacidcomplexesonegghatchingandnaupliusmetamorphosisofPenaeuschinensisisbetterthanthatoflanthanum.Withregardtothepositiveeffect,lanthanum-prolinecomplexisbetterthanLanthanum-phenylalaninecomplex.