简介：IntroductionAlthoughtheapplicationofmicrowavetechniquehasbeenreportedasanewtypeofenergysourcechemically,itisonlyinrecentyearsthatthistechniquehasbeenusedastheenergysourcefororganicsynthesis.In1986,R.Gedye,etal.,publishedthereportofthebenzoatesynthesisfromtherespectivereactionsbetweenbenzenecarboxylicacidandmethanol,propanolorbutanolundermicrowaveheatingandthecatalysisofH2SO4.
简介：Theenergytransmissionofthelongmicrowavepulseforthefrequencyof2.45GHzand5.8GHzisstudiedbyusingtheelectronfluidmodel,wheretheratecoefficientsarededucedfromtheBoltzmannequationsolvernamedBOLSIG+.Thebreakdownthresholdsfordifferentairpressuresandincidentpulseparametersarepredicted,whichshowgoodagreementwiththeexperimentaldata.Belowthebreakdownthreshold,thetransmittedpulseenergyisproportionaltothesquareoftheincidentelectricfieldamplitude.Whentheincidentelectricfieldamplitudehigherthanthebreakdownthresholdincreases,thetransmittedpulseenergydecreasesmonotonouslyatahighairpressure,whileatalowairpressureitfirstdecreasesandthenincreases.Wealsocomparethepulseenergytransmissionforthefrequencyof2.45GHzwiththecaseof5.8GHz.
简介：Multipaction,causedbythesecondaryelectronemissionphenomenon,hasbeenachallengeinspaceapplicationsduetotheresultingdegradationofsystemperformanceaswellasthereductionintheservicelifeofhighpowercomponents.Inthispaperwereportanovelapproachtorealizeaneffectiveincreaseinthemultipactionthresholdbyemployingmicro-poroussurfaces.Twomicro-porousstructures,i.e.,aregularmicro-porousarrayfabricatedbyphotolithographypatternprocessingandanirregularmicro-porousarrayfabricatedbyadirectchemicaletchingtechnique,areproposedforsuppressingthesecondaryelectronyield(SEY)andmultipactionincomponents,andthebenefitsarevalidatedboththeoreticallyandexperimentally.Thesesurfaceprocessingtechnologiesarecompatiblewiththemetalplatingprocess,andoffersubstantialflexibilityandaccuracyintopologydesign.Thesuppressioneffectisquantifiedforthefirsttimethroughtheproperfittingofthesurfacemorphologyandthecorrespondingsecondaryemissionproperties.Insertionlosseswhenusingthesestructuresdecreasedramaticallycomparedwithregularmillimeter-scalestructuresonhighpowerdielectricwindows.SEYtestsonsamplesshowthatthemaximumyieldofAg-platedsamplesisreducedfrom2.17to1.58fordirectlychemicaletchedsamples.MultipactiontestingofactualC-bandimpedancetransformersshowsthatthedischargethresholdsoftheprocessedcomponentsincreasefrom2100Wto5500Wforphotolithographypatternprocessingand7200Wfordirectchemicaletching,respectively.Insertionlossesincreasefrom0.13dBtoonly0.15dBforbothsurfacetreatmentsinthetransmissionband.Theexperimentalresultsagreewellwiththesimulationresults,whichoffersgreatpotentialinthequantitativeanti-multipactiondesignofhighpowermicrowavecomponentsforspaceapplications.
简介：Desorptionofvolatileorganiccompounds(VOCs)frompolymericadsorbentsbymicrowavewasinvestigatedexperimentally.Twokindsoforganiccompounds,benzeneandtoluene,wereseparatelyusedasadsorbatesinthiswork.Resultsshowedthattheapplicationofmicrowavetoregeneratethepolymericadsorbentsnotonlycangethigherregenerationefficiencyincomparisonwiththeuseofheatregeneration,butalsomakethetemperaturesofthefixedbedsmuchlowerthanthatwhenusingtheheatregenerattonTheweakerthepolarityofapolymericadsorbent,theeasieritsregenerationwas.
简介：Microwaveradiationwasappliedtothedetectionofmetamizoiesodiumbycyclicvoltammetry.TheelectrochemicalcharacteristicsofmetamizoiesodiumwerestudiedbycyclicvoltammetryatGCelectrodeundermicrowaveradiationandaconsiderablecurrentenhancementwasobservedformetamizoiesodiuminaqueous0.05mol/LH_2SO_4.Undertheoptionalconditions,metamizoiesodiumwasdeterminedintheabsenceandpresenceofmicrowaveactivation.Intheabsenceofmicrowaveactivationcyclicvoltammogramofmetamizoiesodiumshowsgoodlinearrelationshipinaconcentrationrangeof8.0×10~(-5)—1.0×10~(-3)mol/Linaqueous0.05mol/LH_2SO_4withadetectionlimitof6.75×10~(-6)mol/L(S/N=3)andtheequationoflinearregressionisI_p=12.973c-0.1905(R~2=0.9996,n=6);inthepresenceof80Wmicrowaveactivationcyclicvoltammogramofmetamizoiesodiuminshowsgoodlinearrelationshipinaconcentrationrangeof4.0×10~(-5)—1.0×10~(-3)mol/Linaqueous0.05mol/LH_2SO_4withadetectionlimitof4.41×10~(-6)mol/L(S/N=3)andtheequationoflinearregressionisI_p=25.107c-0.1193(R~2=0.9973,n=7).Thecurrentinthepresenceof80Wmicrowaveactivationincreasestoabout2ordersofmagnitudecomparedwiththatintheabsenceofmicrowaveactivation.Theproposedmethodinthepresenceofmicrowaveactivationshowedhighselectivityandsensitivity,andthesamplingofthedisposalmethodissimple.ThemethodwasverifiedbythedeterminationofMetamizoieSodiumtabletwithsatisfactoryresults.
简介：Wepresentamethodtogenerateafrequency-doubledmicrowavesignalbyemployingacoupling-modulatedringresonator.CriticalcouplingisachievedwhentheresonatorintrinsiclossisperfectlybalancedbytheexternalcouplingenabledbyaMach–Zehnderinterferometercoupler.Thehighsuppressionofthecarrierleadstoacleantwo-toneopticalsignalwiththefrequencyintervaltwotimeslargerthanthatoftheinputmicrowavefrequency.Thebeatingofthetwo-tonesignalataphotodiodegeneratesthefrequencyupconvertedmicrowavesignal.Atheoreticalmodelisestablishedtoanalyzethemodulationprocessandthemicrowavesignalgeneration.Experimentalresultsshowthattheelectricalharmonicsuppressionratioisaround~20dB(29dB)foraninputmicrowavesignalwith5dBm(10dBm)power.
简介：Inthispaper,MPt/C(M=La,Nd)catalystsofPEMFCweresynthesizedbymicrowaveradiationprocess.ThecrystallinityandstructureofcatalystswererespectivelyanalyzedbyXRDandnitrogenadsorptiontests.Theactivityofcatalystswasinvestigatedbyelectrochemistryexperiment.Theresultsshowedthat:1)comparedwithPt/Ccatalystpreparedbytypicalimpregnation-reductionprocess,thesizeofMPt/CcatalystparticledecreasedandtheavailablecrystalforO2reductionincreased;2)theMPt/CcatalystshadrelativelyhighBETsurfaceareas;and3)thesecrystaltransformationsoftheMPt/Ccatalystbroughthightheelectrocatalyticactivity,andasaresult,improvedthepowerofPEMFC.
简介：Poly(N-vinyl-2-pyrrolidone)(PVP)-stabilizedrutheniumnanorodswithhighaspectratiobyrefluxingruthenium(Ⅲ)chlorideinn-propanolhavebeensuccessfullypreparedbymeansofafacileandrapidmicrowaveheatingforthefirsttime.Thestructureandmorphologyoftheobtainedproductswerecharacterizedbytransmissionelectronmicroscopy(TEM),selectareaelectrondiffraction(SAED),ultraviolet-visiblespectrophotometry(UV-vis),X-rayphotoelectronspectroscopy(XPS)andFouriertransformspectroscopy(FT-IR).XPSanalysisrevealsthatthenanorodswereinthemetallicstate.TEMimagesshowedthatrutheniumnanorodshadanobviousone-dimensionalstructurewiththeaspectratiorangedfrom5to40nmandlengthupto600nm.SAEDpatternsindicatedthatthenanorodsweresingle-crystallinewithahexagonalstructure.
简介：Wedemonstrateasilicon-basedmicrowavephotonicfilter(MPF)withflattoppassbandandadjustablebandwidth.TheproposedMPFisrealizedbyusinga10th-ordermicroringresonator(MRR)andaphotodetector,bothofwhichareintegratedonaphotonicchip.Thefullwidthathalf-maximum(FWHM)bandwidthoftheopticalfilterachievedatthedropportofthe10th-orderMRRis21.6GHz.Therippleofthepassbandislessthan0.3dB,whiletherejectionratiois32dB.Byadjustingthedeviationoftheopticalcarrierwavelengthfromthecenterwavelengthoftheopticalbandpassfilter,thebandwidthoftheMPFcanbegreatlychanged.Intheexperiment,theFWHMbandwidthoftheproposedMPFistunedfrom5.3to19.5GHz,andtherejectionratioishigherthan30dB.
简介：ZnOnanoparticleswithverynarrowsizedistributionweresynthesizedbycouplinghomogeneousprecipitationwithmicroemulsionunderpulsedmicrowaveheating.TheconditionsofpreparingZnOnanoparticleswereinvestigated.TheproductswerecharacterizedwithDTA,TGA,XRD,TEMandUV-Vis.ThesynthesizedZnOnanoparticeshadmuchstrongerultravioletabsorptivitythannormalZnOpowders;theaveragesizeofproductswassensitivetothevariationofthepowerordurationofmicrowaveirradiation.
简介：Photonic-assistedmicrowavefrequencyidentificationwithdistinctfeatures,includingwidefrequencycoverageandfasttunability,hasbeenconceivedasakeytechniqueforapplicationssuchascognitiveradioanddynamicspectrumaccess.Theimplementationsbasedoncompactintegratedphotonicchipshaveexhibiteddistinctadvantagesinfootprintminiaturization,lightweight,andlowpowerconsumption,instarkcontrastwithdiscreteoptical-fiber-basedrealization.However,reportedchip-basedinstantaneousfrequencymeasurementscanonlyoperateatasingle-toneinput,whichstringentlylimitstheirpracticalapplicationsthatrequirewidebandidentificationcapabilityinmodernRFandmicrowaveapplications.Inthisarticle,wedemonstrate,forthefirsttime,awideband,adaptivemicrowavefrequencyidentificationsolutionbasedonasiliconphotonicintegratedchip,enablingtheidentificationofdifferenttypesofmicrowavesignalsfrom1to30GHz,includingsingle-frequency,multiple-frequency,chirped-frequency,andfrequency-hoppingmicrowavesignals,andeventheircombinations.ThekeycomponentisahighQ-factorscanningfilterbasedonasiliconmicroringresonator,whichisusedtoimplementfrequency-to-timemapping.Thisdemonstrationopensthedoortoamonolithicsiliconplatformthatmakespossibleawideband,adaptive,andhigh-speedsignalidentificationsubsystemwithahighresolutionandalowsize,weight,andpower(SWaP)formobileandavionicapplications.
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