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简介:Recently,intelligentorsmartmaterialsandstructureshavebeenreceivedmoreandmoreattentionduetotheirdistinguishedmulti-fieldcouplingpropertiesandwideapplicationsinaerospace,automobiles,civilstructures,medicaldevices,informationstorage,energyharvestingandsoon.Itisofacademicchallengetofullyunderstandthecomplexmulti-fieldcouplingbehaviorsofvarioussmartmaterialsandstructures,andofengineeringsignificancetoenhancetheperformanceandreliabilityofthese
简介:Phenoliccompounds,themostabundantsecondarymetabolitesinplants,havereceivedmoreandmoreattentioninrecentyearsbecauseoftheirdistinctbioactivities.Thisreviewsummarizesdifferenttypesofphenoliccompoundsandtheirextractionandanalyticalmethodsusedintherecentreports,involving59phenoliccompoundsfrom52kindsofplants.Theextractionmethodsincludesolid–liquidextraction,ultrasound-assistedextractions,microwave-assistedextractions,supercriticalfluidextraction,andothermethods.Theanalysismethodsincludespectrophotometry,gaschromatography,liquidchromatography,thin-layerchromatography,capillaryelectrophoresis,andnear-infraredspectroscopy.Afterillustratingthespecificconditionsoftheanalyticalmethods,theadvantagesanddisadvantagesofeachmethodarealsosummarized,pointingouttheirrespectivesuitability.Thisreviewprovidesvaluablereferenceforidentificationand/orquantificationofphenoliccompoundsfromnaturalproducts.
简介:Hydrogen,thecleanestandmostpromisingenergyvector,canbeproducedbysolarintochemicalenergyconversion,eitherbythephotocatalyticdirectsplittingofwaterintoH2andO2,or,moreefficiently,inthepresenceofsacrificialreagents,e.g.,intheso-calledphotoreformingoforganics.Efficientphotocatalyticmaterialsshouldnotonlybeabletoexploitsolarradiationtoproduceelectron–holepairs,butalsoensureenoughchargeseparationtoallowelectrontransferreactions,leadingtosolarenergydriventhermodynamicallyup-hillprocesses.RecentachievementsofourresearchgroupinthedevelopmentandtestingofinnovativeTiO2-basedphotocatalyticmaterialsarepresentedhere,togetherwithanoverviewonthemechanisticaspectsofwaterphotosplittingandphotoreformingoforganics.Photocatalyticmaterialswereeither(i)obtainedbysurfacemodificationofcommercialphotocatalysts,orproduced(ii)inpowderformbydifferenttechniques,includingtraditionalsolgelsynthesis,aimingatengineeringtheirelectronicstructure,andflamespraypyrolysisstartingfromorganicsolutionsoftheprecursors,or(iii)inintegratedform,toproducephotoelectrodeswithindevices,byradiofrequencymagnetronsputteringorbyelectrochemicalgrowthofnanotubearchitectures,orphotocatalyticmembranes,bysupersonicclusterbeamdeposition.
简介:在不同水和年龄和它充满力量的生长法律获得似水泥的材料的水和产品的作文和微观结构,合成似水泥的材料的最佳的比例根据波特兰水泥32.5R镇静的水泥clinker的化学作文被决定,CSA42.5sulphoaluminate水泥和二石膏(CS)。在不同水和年龄的合成似水泥的材料的描述被NMR,XRD和SEM技术进行。水和的机制被探索。测试的压缩力量随水和年龄的增加逐渐地堵住增加,这被显示出。合成似水泥的材料的微观结构能在水和过程从Al-O八面体被变成Al-O四面体。与Si-O四面体和Al-O四面体形成的含水的碱aluminiumsilicate。Si-O四面体的聚合的度逐渐地增加了,并且似水泥的材料的结构的力量继续增加。clinker矿物质的衍射山峰逐渐地与水和年龄的延期减少了。完全含水的CaSO4在导致了似水泥的材料的高早的力量的水和期间在船尾生产。合成似水泥的材料的早水和产品是在船尾与针酒吧结构。主要中间和最后一水和产品是有稠密的棱柱的形状的CSH胶化和CH胶化。合成似水泥的材料的显微镜的毛孔逐渐地减少了并且改进了充满块的以后的力量。强壮的支持我的外面被为区域提供。
简介:Theuseofsolarenergytodrivethechemicalandenergyprocesses,andthechemicalstorageofsolarenergyarethekeyelementstomovetoalow-carboneconomy,sustainablesocietyandtofosterenergytransition.Forthisreason,thereisafast-growingscientificinterestonthissubject,whichispartofthegeneraleffortforasolar-drivenchemistryandenergy,thechemistryofthefuture.Torealizethis
简介:TheBe-basedmaterialswithmanyparticularpropertiesleadtoanimportantresearchsubject.Theinvestigationprogressesinthefabricationtechnologiesareintroducedhere,includingmainthreekindsofBe-basedmaterials,suchasBe–Cucapsule,Be_2Cablatorandhigh-purityBematerial.ComparedwiththepioneerworkgrouponBe-basedmaterials,thedifferencesinBe–Cutargetfabricationweredescribed,andagrainrefinementtechniquebyanactivehydrogenreactionforBecoatingwasproposeduniquely.Be_2CcoatingswerefirstpreparedbytheDCreactivemagnetronsputteringwithahighdepositionrate(~300nm/h).PurepolycrystallineBe_2Cfilmswithuniformmicrostructures,smoothsurface,highdensity(~2.2g·cm~3)andgoodopticaltransparencywerefabricated.Inaddition,thehigh-purityBematerialswithmetalimpuritiesinappmmagnitudewerefabricatedbythepyrolysisoforganometallicBe.
简介:Thisperspectivepaperintroducestheconceptthatnanocarbonsandrelatedmaterialssuchascarbondotsareaninterestingintrinsicphotocatalyticsemiconductingmaterial,andnotonlyamodifieroftheexisting(semiconducting)materialstopreparehybridmaterials.Thesemiconductingpropertiesofthenanocarbons,andthepossibilitytohavethebandgapwithinthevisible-lightregionthroughdefectbandengineering,introductionoflightheteroatomsandcontrol/manipulationofthecurvatureorsurfacefunctionalizationarediscussed.Thesematerialsareconceptuallydifferentfromthe'classical'semiconductingphotocatalysts,becausesemiconductordomainswithtuneablecharacteristicsareembeddedinaconductivecarbonmatrix,withthepresenceofvariousfunctionalgroups(asC=Ogroups)enhancingchargeseparationbytrappingelectrons.Thesenanocarbonsopenarangeofnewpossibilitiesforphotocatalysisbothforenergeticandenvironmentalapplications.Theuseofnanocarbonsasquantumdotsandphotoluminescentmaterialswasalsoanalysed.
简介:Preparationofhierarchicallyporous,heteroatom-richnanostructuredcarbonsthroughgreenandscalableroutesplaysakeyroleforpracticalenergystorageapplications.Inthiswork,naturallyabundantlignocellulosicagriculturalwastewithhighinitialoxygencontent,hazelnutshells,werehydrothermallycarbonizedandconvertedintonanostructured‘hydrochar’.Environmentallybenignceramic/magnesiumoxide(MgO)templatingwasusedtointroduceporosityintothehydrochar.Electrochemicalperformanceoftheresultingmaterial(HM700)wasinvestigatedinaqueoussolutionsof1MH2SO4,6MKOHand1MNa2SO4,usingathree-electrodecell.HM700achievedahighspecificcapacitanceof323.2F/gin1MH2SO4(at1A/g,-0.3to0.9Vvs.Ag/AgCl)duetothecontributionsofoxygenheteroatoms(13.5wt%)tothetotalcapacitancebypseudo-capacitiveeffect.Moreover,amaximumenergydensityof11.1Wh/kgandamaximumpowerdensityof3686.2W/kgwereattainedforthesymmetricsupercapacitoremployingHM700aselectrodematerial(1MNa2SO4,E=2V),makingthedevicepromisingforgreensupercapacitorapplications.
简介:Theparticlesizedistributionofbedmaterialsinthesandyriverbedofalluvialriversisimportantinthestudyoftopicssuchasfriction,riverbedevolution,erosion,andsiltation.Italsocanreflectthedependencyrelationbetweenriverbedsedimentandflowintensity.Inthispaper,thecriticalpatternofsedimentmovementinthenear-wallregionofasandyriverbedwasanalyzed.Accordingtotheprincipleofmomentumbalance,thecriticalsettling-risingconditionofbedmaterialinasandyriverbedwasfoundtobeinstantaneousturbulentvelocityequalto2.7timesthesedimentsettlingvelocityinquiescentwater.BasedonaverticalinstantaneousturbulentvelocitywithaGaussiandistribution,atheoreticalrelationforcalculatingtheparticlesizedistributionofbedmaterialsinasandyriverbedwithoutpre-knowncharacteristicgrainsizeswasdevelopedbysolvingastochasticequation.Theformulaisverifiedusingmeasureddata,andtheresultsshowthattheproposedformulawasinaccordancewiththemeasureddata.Thisstudyhastheoreticalsignificanceandpracticalvaluefordeterminingthebedmaterialparticlesizedistributionofthesandybedofalluvialrivers.
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简介:ThenanostructuredAl-basedcompositespossessthecombinationofhighyieldstrengthandgoodductility.Inthispaper,amicromechanicalmodelispresentedtosimulatethemechanicalresponseofbimodalnanostructuredAlandtheparticle-reinforcedaluminummatrixcomposite(PAMC).Theconstitutiverelationsfordifferentphasesareaddressedinthemodel,aswellasthecontributionofmicrocracks.NumericalresultsshowthatthemodelcansuccessfullydescribetheenhancedstrengthandductilityofthebimodalnanostructuredAl,andthepredictionsofthePAMCareingoodagreementwiththeexperimentaldata.ItisworthnotingthatthestrengthandductilityaresensitivetothevolumefractionofconstituentsandthedistributionofmicrocracksinbothbimodalnanostructuredAlandPAMC.Therefore,thepresenttheoreticalresultscanbeusedtooptimizethemicrostructureforimprovingthemechanicalpropertiesofnanostructuredAl-basedcomposites.
简介:关于mesomechanics的一个新方法有限元素的研究被建议预言山峰砍mesoscopic上的材料放大的mudded置闰的力量。基于几何、机械的参数,与样品获得的种类失败标准一起变丑特征,样品上的单轴的压缩测试通过一个有限元素的模型被模仿,它从单轴的压缩测试的实验室产出与数据一致的值,暗示方法是合理的。把模型基于这,一shear测试被执行计算山峰砍mudded置闰的力量,与在文学报导的价值一致,从而提供为调查mudded的机械性质的一条新途径置闰材料。
简介:我们为说明唯一的结构和磷灰石蛋白质composites的技工性质的atomicto中央规模过程的探索考察衔接规模的模拟研究。当如此的复杂biocomposites的原子结构和作文仅仅部分被知道,我们的建模研究的第一部分(i)被奉献给无机器官的composites的现实主义的水晶成核情形。从单个离子,从主题形成的机制的最近的卓见范围,成熟反应和nanocrystals的组织工会的协会开始,包括他们有控制生长的分子的一半的相互影响。在这个基础上,(ii)可靠的造为没有偏见的按比例增加裁定模型能被导出为体积材料建模。这被例示为(像瓷釉)磷灰石蛋白质composites,包含直到106原子当模特儿提供10nm长度规模的一篇现实主义的报道,虽然模型变粗被用来到达m,长度可伸缩。在这个基础上,一系列变丑和破裂模拟研究被执行并且帮助文饰biocomposite坚硬,粘性,坚韧,self-healing和破裂机制。补充试验性的工作,这些建模研究提供特别地详细的卓见进层次合成结构和有利机械性质的关系。
简介:Theexistingabsorptioncoefficientmeasurementinawatertubeislimitedinlowfrequencyduetothelimitationofthepulsetubelength.Awide-bandpulsetubemethodbasedonthepost-processinginversefilterisproposed.Afterobtainingtheresponseoftheentiresystem,thetransducerisexcitedwithwide-band,short-durationsignals.Then,thereceivedsignalsareprocessedwithinversefiltersandthe'blurred'reflectivesignalsofstandardreflectorandtestsamplearerecoveredrespectively,finally,thereflectioncoefficientandabsorptioncoefficientarecalculated.Simulationworkisimplementedtoverifytheadvantageofpostprocessinginversefilteroverpre-processinginversefilterintermsoflowfrequencymeasurement.Toverifytheproposedmethod,twodifferentwide-bandpulsesintheseparatefrequencyrangesareadoptedtomeasurethesamerubbermaterial.Theexperimentalresultsindicatethatthewide-bandpulsemethodandCW(ContinuousWave)pulsemethodhavegoodagreementinbothlowfrequencyrangeandhighfrequencyrange.Wide-bandpulsemethodisofhighefficiency,andthelowfrequencyreaches350Hz,whichisabletoextendthelowfrequencyrange.