简介:ThestructureandelectrochemicalpropertiesofanewlowcobalthydrogenstorageelectrodealloysLa1-xLixNi3.2Co0.3Al0.3(0≤x≤0.2)wereinvestigatedwithadifferentadditionsofLiinreplacementofLa.WiththeincreaseofLicontentsthemaximumdischargecapacityincreasesfrom240mAh·g-1(x=0)to328.4mAh·g-1(x=0.1)andthecyclestabilityisimprovedcorrespondingly.ThecapacitydecaycanremaiN28.6%(x=0.2)after230charge/dischargecycles.Thehighratedischarge(HRD)abilityofthealloys(x≤0.1)isimprovedandthebestHRDis34.1%(x=0.1)underthedischargecurrentdensity1200mA·g-1.ItisfoundthatthepreparedalloysarebasicallycomposedofLaNi5asmatrixphaseandLaNi3assecondphase(x≤0.1).ButtheabundanceofLaNi3phasedramaticallydecreaseswithincreasingx.Whenx=0.2,anewphaseAl(NiCo)3isformed.
简介:摘要目的评价0.3T磁共振在二级医院应用价值。方法回顾性分析我院应用OPENMARKⅢ磁共振成像系统检查15407例病人的图像状况,阳性率,主要疾病谱系诊断结果和优势。结果15407例检查后,图像总甲级率98.25%、总乙级率1.4%、废片率0.35%。其中胸腹部图像废片率61%。总阳性率85.3%,其中含不易为平片和CT发现的颅内微小血管畸形、脑干小出血灶、微小腔隙性梗塞、急性期脑梗塞、脊髓轻度损伤、椎管内占位、关节腔少量积液、早期骨坏死、骨挫伤、隐匿性骨折、关节小韧带损伤、半月板退变及损伤共1667例。结论该磁共振系统在颅脑、脊柱、四肢关节疾病诊断中具有重要价值。结合其维修费用低、购买价格低特点,在二级医院有较高实用价值。
简介:Sn-dopedTiO_2nanoparticleswithhighsurfaceareaof125.7m~2·g~(-1)aresynthesizedviaasimpleone-stephydrothermaimethodandexploredasthecathodecatalystsupportforprotonexchangemembranefuelcells.ThesynthesizedsupportmaterialsarestudiedbyX-raydiffractionanalysis,energydispersiveX-rayspectroscopyandtransmissionelectronmicroscopy.Itisfoundthattheconductivityhasbeengreatlyimprovedbytheadditionof30mol%SnandPtnanoparticlesarewelldispersedonTi_(0.7)Sn_(0.3)O_2supportwithanaveragesizeof2.44run.ElectrochemicalstudiesshowthattheTi_(0.7)Sn_(0.3)O_2nanoparticleshaveexcellentelectrochemicalstabilityunderahighpotentialcomparedtoVulcanXC-72.Theas-synthesizedPt/Ti_(0.7)Sn_(0.3)O_2exhibitshighandstableelectrocatalyticactivityfortheoxygenreductionreaction.ThePt/Ti_(0.7)Sn_(0.3)O_2catalystreservesmostofitselectrochemicallyactivesurfacearea(ECA),anditshalfwavepotentialdifferenceis11mV,whichislowerthanthatofPt/XC-72(36mV)under10hpotentialholdat1.4Vvs.NHE.Inaddition,theECAdegradationofPt/Ti_(0.7)Sn_(0.3)O_2is1.9timeslowerthancommercialPt/XC-72under500potentialcyclesbetween0.6Vand1.2Vvs.NHE.Therefore,theassynthesizedPt/Ti_(0.7)Sn_(0.3)O_2canbeconsideredasapromisingalternativecathode,catalystforprotonexchangemembranefuelcells.
简介:Nearlysingle-phaseandpolycrystallinecharge-density-wavecompoundK_(0.3)MoO_3havebeenpreparedbyusingasimplemethod.Inthiswork,K_2CO_3andMoO_3wereusedasstartingmaterialsandreactedbyhotisostaticpressing(HIP)sintering.TheproductisnearlysinglephaseK_(0.3)MoO_3determinedbyX-raypowderdiffraction(XRD)andenergydispersivespectroscopy(EDS).MeasurementoftemperaturedependenceofresistivityrevealsthatthetransportpropertyofpolycrystallineK_(0.3)MoO_3obviouslydiffersfromthatofsinglecrystalduetothegrainboundariesandtheanisotropicstructureinthiskindofcompound.