学科分类
/ 25
500 个结果
  • 简介:Inthispaper,weshowthatnewmodifieddoublecosinetrigonometricsumsintroducedin[1]areinappropriate,theclassofdoublesequencesJdintroducedthereisunusableforsuchsumsandconsequentlytheresultsobtainedinitarecompletelyincorrect.WehereintroduceappropriatemodifieddoublecosinetrigonometricsumsmakingtheclassJdusableconsideringaparticulardoublecosinetrigonometricseries.

  • 标签: L1-convergence double NULL sequence COSINE trigonometric
  • 简介:ThehighlydispersedPt–ReOX(x≤1)sitesca.0.5nminsizewereformedviaasuccessiveandstronginteractionoftheReprecursorwithtitaniaandthenofthePtcomplexwithdepositedlow-valentrheniumoxideclusters.Thesize,chargeandchemicalcompositionwerecharacterizedbymeansofHRTEM/STEMwithEDXmapping,XPS,andFTIRS.ThesesiteswithRe/Pt=2wereshowntobehighlyactiveandselectiveinthehydrogenationofcarboxylicacidtoalcoholunderverymildconditions(T=130°C,P=50bar).ThereactionrateconstantforthehydrogenationofhexanoicacidincreasedlinearlywiththePtcontent.Asforthehomogeneouspincer-typeRu-organiccomplexes,theactivePt–ReOXsitescandissociateheterolyticallythemolecularhydrogenwiththeformationofhydroxylgroupsandPthydrideforhydrogenationofthecarboxylicgroup.Indeed,TOFof20h-1andselectivityof98%–99%areapproachingthevaluestypicalofhomogeneouscatalysts.Thefirstorderkineticsdescribedwelltheexperimentaldataobtainedinawiderangeofreactionconditions.

  • 标签: 选择性加氢催化剂 铂络合物 活性位点 二氧化钛 再氧化 羧酸
  • 简介:ByFP-LAPWcalculations,thestructural,elastic,DebyeandCurietemperatures,electronicandmagneticpropertiesofCo2VAlareinvestigated.TheresultsindicatethatFerromagnetic(FM)phaseismorestablethanAntiFerromagnetic(AFM)andNon-magnetic(NM)ones.Inaddition,C11–C12>0,C44>0,andB>0soCo2VAlisanelasticallystablematerialwithhighDebyetemperature.Also,theB/Gratioexhibitsaductilitybehavior.TherelativelyhighCurietemperatureprovidesitasafavorablematerialforspintronicapplication.It’selectronicandmagneticpropertiesarestudiedbyGGA+Uapproachleadingtoa100%spinpolarizationatFermilevel.

  • 标签: 第一性原理计算 高居里温度 半金属 化合物 原子力显微镜 弹性材料
  • 简介:Theaerobicoxidationofglycerolprovidesaneconomicallyviableroutetoglyceraldehyde,dihydroxyacetoneandglycericacidwithversatileapplications,forwhichmonometallicPt,AuandPdandbimetallicAu–Pt,Au–PdandPt–PdcatalystsonTiO2wereexaminedunderbase-freeconditions.PtexhibitedasuperioractivityrelativetoPd,andAu–PdandPt–PdwhileAuwasessentiallyinactive.ThepresenceofAuontheAu–Pt/TiO2catalystsledtotheirhigheractivities(normalizedperPtatom)inawiderangeofAu/Ptatomicratios(i.e.1/3–7/1),andtheonewiththeAu/Ptratioof3/1exhibitedthehighestactivity.SuchpromotingeffectisascribedtotheincreasedelectrondensityonPtviatheelectrontransferfromAutoPt,ascharacterizedbythetemperature-programmeddesorptionofCOandinfra-redspectroscopyforCOadsorption.Meanwhile,thepresenceofAuonAu–Pt/TiO2,mostlikeduetotheobservedelectrontransfer,changedtheproductselectivity,andfacilitatedtheoxidationofthesecondaryhydroxylgroupsinglycerol,leadingtothefavorableformationofdihydroxyacetoneoverglyceraldehydeandglycericacidthatwerederivedfromtheoxidationoftheprimaryhydroxylgroups.ThesynergeticeffectbetweenAuandPtdemonstratesthefeasibilityintheefficientoxidationofglyceroltothetargetedproducts,forexample,byrationaltuningoftheelectronicpropertiesofmetalcatalysts.

  • 标签: 铂催化剂 二氧化钛 双金属 游离氧 铂钯催化剂 二羟基丙酮
  • 简介:BecauseERstressisoneofthesignalingpathwaysinvolvedintheregulationofautophagy,wehypothesizedthatERstressmightalsoplayanimportantroleinradiation-inducedautophagy.SHG44andHeLacellswereirradiatedwithX-raysandcarbonionsof30and75keV/mat2Gy.TheexpressionlevelsofBip,amajorindicatorofUPR,at4and24hpost-irradiationareshowninFig.1(a)and(b)forSHG44andHeLacells,respectively.

  • 标签: PHOSPHORYLATION Tumor Cells
  • 简介:Theeffectsofcarbon-ionirradiationoncancercelltelomerefunctionhavenotbeencomprehensivelystudied[1].Ourpreviousreportshowedthatcancercellswithtelomeredysfunctionweremoresensitivetocarbon-ionirradiation,butthemechanismthatlinktelomeredysfunctionandcancercellinactivationhasnotbeeninvestigated.

  • 标签: Telomere-mitochondrion LINK Contributed
  • 简介:Radiotherapyisacommontreatmentmodalityforheadandneckcancers,nasopharyngealcancers,primarybraintumorsandbrainmetastases.Alargenumberofpatientsintheworldwithprimaryormetastaticbraintumorswillrequirelargevolumeorwholebrainirradiationeveryyear.However,therapeuticirradiationnotonlykillstumorcells,butalsoinjuresnormalbraintissue,whichiscommonlyassociatedwithsignificantfunctionalmorbidityanddecreasedqualityoflifeinpatientstreatedwithbrainradiotherapy[1].

  • 标签: Protective Effects Hydroxysaffor
  • 简介:TheenigmaticchargedstatesZc(3900),Zc(4020),Zc(4050),Zb(10610),andZb(10650)arestudiedwithinacoupled-channelSchr¨odingermodel[1],whereradiallyexcitedquark-antiquark(qˉq)pairs,withthesameangularmomentaandisospinasthea1(1260)andb1(1235),arestronglycoupledtotheirOkubo-Zweig-Iizuka-allowedde-caychannelsDˉD+ˉDDandDˉD,orBˉB+ˉBBandBˉB,inSandD-wave.Poles,matchingtheexperimentalmassandwidthofalltheabovestates,arefoundbyvaryingonlytwofreeparameters.In

  • 标签: Radially EXCITED AXIAL
  • 简介:AtomicallythinMoS2filmshaveattractedsignificantattentionduetoexcellentelectricalandopticalproperties.Thedevelopmentofdeviceapplicationsdemandstheproductionoflarge-areathinfilmwhichisstillanobstacle.Inthisworkwedevelopedafacilemethodtodirectlygrowlarge-areaMoS2thinfilmonSiO2substrateviaambientpressurechemicalvapordepositionmethod.Thecharacterizationsbyspectroscopyandelectronmicroscopyrevealthattheas-grownMoS2filmismainlybilayerandtrilayerwithhighquality.Back-gatefield-effecttransistorbasedonsuchMoS2thinfilmshowscarriermobilityupto3.4cm2V-1s-1andon/offratioof105.Thelarge-areaatomicallythinMoS2preparedinthisworkhasthepotentialforwideoptoelectronicandphotonicdeviceapplications.

  • 标签:
  • 简介:Wemeasurethecurrent–voltage(I–V)characteristicsforthesinglecrystalofTl0.4K0.41Fe1.71Se2withthesuperconductingtransitiontemperature(TC)around30.5K,undera10Tmagneticfieldappliedperpendicularandparalleltotheabplane.WefindthattheshapesoftheI–Visothermsareverydifferentfromthedescriptionbythevortex-glass(VG)model.CombiningtheoreticalcalculationsandanalysisoftheρH⊥ab–TandρHab–Tdata,wegiveanexplicitdiscussionoverthesuitabilityoftheVGmodelfortheA0.8Fe2Se2superconductors,andpointoutthepossibilityofthematerialactingasaconvenientplatformforre-examinationandfurtherstudyofthecomplexvortexbehaviorsinthelayeredsuperconductors.

  • 标签: 玻璃模型 适用性 旋涡 单晶 层状超导体 超导转变温度
  • 简介:Theoreticalmodelsofstellarevolutionpredictnegligiblequantitiesof6Li,9Be,and11Binthehydrogenburningphasesofastar’sevolution[1].TheprimordialBig-Bangnucleosynthesis(BBN)modelmightbemoregenerousinitsproductionoftheseelements[2].Theradiative-capturecrosssectionforprotoncaptureon11Bleadingto12CissmallatastrophysicallyinterestingenergiesbecauseofthelargeCoulombbarrier.

  • 标签: FACTORS LOW ENERGIES
  • 简介:分析中等职业学校以校企合作为基础现代学徒制存在问题基础,对近年来实施“现代学徒制”办学模式各个学校所取得经验和问题进行了相关调研,提出了确保中等职业学校采取“现代学徒制”办学模式具有可行性应采取措施。

  • 标签: 职业教育 中等职业学校 现代学徒制 校企合作
  • 简介:近年来,随着半导体工艺技术迅速发展,质子单粒子效应研究重要性上升到了高度。综述了国际纳米集成电路质子单粒子效应研究主要进展,如低能质子成为纳米集成电路单粒子效应和软错误率主要贡献因素,中高能质子新型器件材料(如钨)核反应研究成为质子单粒子效应新热点问题,介绍了中国原子能科学研究院纳米集成电路低能质子实验方面开展相关工作

  • 标签: 质子 单粒子效应 核反应 直接电离
  • 简介:Tonguesquamouscellcarcinoma(ToSCC)isthemostcommontypeofheadandnecksquamouscellcarcinomaandisthesixthleadingcauseofcancerdeathsworldwide[1].Inclinicaloncology,radiationtherapyisastandardtreatmentusedfortumors.Numerousstudieshaveshownthatconventionalradiotherapyusedincancertreatmentmayincreasetheriskofmetastasisofmalignanttumorcells[2–4].Toimprovepatientsurvival,thepotentialformetastasisoftumorsinresponsetoradiationneedstobeaddressed.

  • 标签: SQUAMOUS Cell CARCINOMA
  • 简介:采用sol-gel方法石英玻璃衬底制备出α轴取向多晶Bi4Ti3O12(BIT)薄膜,根据透射谱曲线得到薄膜样品线性折射率2.35,线性吸收系数9.81×10^3cm^-1,光学带隙宽度3.60eV。以脉宽300fs,波长800nm钛蓝宝石脉冲激光光源,利用单光束Z-scan技术测得薄膜样品双光子吸收系数100.31GW·cm^-2,三阶非线性折射率-1.02×10^2GW·cm^-2。实验结果表明,所制备BIT铁电薄膜具有大非线性光学系数,适合应用于光子器件制备。

  • 标签: BI4TI3O12 铁电薄膜 Z-SCAN 三阶非线性光学
  • 简介:Thepresentworkisconcernedwithapenny-shapedDugdalecrackembeddedinaninfinitespaceofone-dimensional(1D)hexagonalquasicrystalsandsubjectedtotwoidenticalaxisymmetrictemperatureloadingsontheupperandlowercracksurfaces.ApplyingDugdalehypothesistothermo-elasticresults,theextentoftheplasticzoneatthecracktipisdetermined.Thenormalstressoutsidetheplasticzoneandcracksurfacedisplacementarederivedintermsofspecialfunctions.Forauniformloadingcase,thecorrespondingresultsarepresentedbysimplifyingtheprecedingresults.Numericalcalculationsarecarriedouttoshowtheinfluenceofsomeparameters.

  • 标签: 裂纹尖端塑性区 无限空间 币形裂纹 一维 加载 QC
  • 简介:Two-dimensional(2D)materialshaveemergedasattractivemediumsforfabricatingversatileoptoelectronicdevices.Recently,few-layermolybdenumdisulfide(MoS2),asashining2Dmaterial,hasbeendiscoveredtopossessboththesaturableabsorptioneffectandlargenonlinearrefractiveindex.Herein,takingadvantageoftheuniquenonlinearopticalpropertiesofMoS2,wefabricatedahighlynonlinearsaturableabsorptionphotonicdevicebydepositingthefew-layerMoS2ontothemicrofiber.WiththeproposedMoS2photonicdevice,apartfromtheconventionalsolitonpatterns,themode-lockedpulsescouldbeshapedintosomenewsolitonpatterns,namely,multiplesolitonmolecules,localizedchaoticmultipulses,anddouble-scalesolitonclusters.Ourfindingsindicatethatthefew-layerMoS2-depositedmicrofibercouldoperateasapromisinghighlynonlinearphotonicdevicefortherelatednonlinearopticsapplications.

  • 标签:
  • 简介:Inthepresentwork,core-shellNi@SiO2catalystswereinvestigatedinordertoevaluatetherelevanceofcatalyticactivityandsurfacestatesofNicoreaswellasNinanoparticlessizetocatalyticpartialoxidationofmethane(POM).ThecatalystswerecharacterizedbyN2adsorption,H2-TPR,XRD,TEMandXPStechniques.Thecatalyticperformanceofthecore-shellcatalystswasfoundtobedependentonthesurfacestatesofcatalyst,whichinfluencedtheformationofproducts.Itwasconsideredthatcarbondioxideformedontheoxidizednickelsites(NiO)andcarbonmonoxideproducedonthereducedsites(Ni).ThesurfacestatesofactivemetalinthedynamicwereinfluencedbothbythesizeofNicoreandtheporosityofsilicashell.However,thecatalyticactivitywouldbedebasedwhenthesizeofNicorewasunderacertainextent,whichcanbeascribedtothefactthecarbondepositionincreasedwiththeincreasingcontentofNiO.TheeffectsofsurfacestatesofNi@SiO2catalystonthecatalyticperformancewerediscussedandthereactionpathwayoverNicoreencapsulatedinsidesilicashellwasproposed.

  • 标签: 催化剂性能 催化部分氧化 SIO2 表面态 甲烷 核壳
  • 简介:Theelectrontransportlayer(ETL)playsanimportantroleinplanarheterojunctionperovskitesolarcell(PSCs),byaffectingthelight-harvesting,electroninjectionandtransportationprocesses,andespeciallythecrystallizationofperovskiteabsorber.Inthiswork,weutilizedacommercialTKD-TiO_2nanoparticlewithasmalldiameterof6nmforthefirsttimetoprepareacompactETLbyspincoating.Thepackingofsmall-sizeparticlesendowedTKD-TiO_2ETLanappropriatesurface-wettability,whichisbeneficialtothecrystallizationofperovskitedepositedviasolution-processedmethod.Theuniformandhigh-transmittanceTKD-TiO_2filmsweresuccessfullyincorporatedintoPSCsasETLs.FurthercarefuloptimizationofETLthicknessgavebirthtoahighestpowerconversionefficiencyof11.0%,whichwasmuchhigherthanthatofPSCusinganETLwiththesamethicknessmadebyspraypyrolysis.ThisTKD-TiO_2providedauniversalsolarmaterialsuitableforthefurtherlarge-scaleproductionofPSCs.TheexcellentmorphologyandtheconvenientpreparationmethodofTKD-TiO_2filmgaveitanextensiveapplicationinphotovoltaicdevices.

  • 标签: 二氧化钛纳米颗粒 太阳能电池 电子传输层 表面润湿性 钙钛矿型 异质结