搜索
专业英语复试题-1Mesocrystals（介晶）areanewclassofnanostructuredsolidmaterials,whicharemostoftenmadeofcrystallographically（晶向）orientednanoparticles.Structuralfeatures,properties,andpossibleapplicationsofmesocrystalsaresummarizedinthispaper.Duetotheiruniquestructuralfeaturesandtheresultingphysicalandphysicochemicalproperties,mesocrystalsareexpectedtoplayasignificantroleinimprovingtheperformanceofmaterialsinmanyapplications.Theseareasdiverseasheterogeneousphotocatalysts,electrodes,optoelectronics,biomedicalmaterials,hardtemplates,andlightweightstructuralmaterials.Inthepast6years,moreandmoreattentionhasbeenpaidtomesocrystallinematerials.Anincreasingnumberofpapershavebeenpublishedintheliterature.Mostofthesefocusedonthecharacterizationofstructuresandtheinvestigationofformationmechanisms.Theresultsindicatethatthestructureandformationmechanismofamesocrystalarerelatedtotheshapeofthenanoparticle,colloidalstabilization,andvectoriallong-rangeinteractionpotentials.Surfaceinteractionbetweenthenanoparticlesplaysacriticalroleduringtheformationprocessofamesocrystalandmayberesponsiblefortheformationofexternalfaces.Thereasonfortheremarkably(almostperfectlyinsomecases)orderedalignmentofnanoparticlesisstillpoorlyunderstood.Specialemphasishasbeenplacedonthedifferentpossibleforcesthatmaydriveorientationandassemblybetweennanoparticles.专业英语复试题-2Thisworkdescribesthereal-timeandquantitativeanalysisofcalciumphosphatemineralizationusingaquartzcrystalmicrobalance(QCM)sensorandsyntheticDNAtemplates.Intypicalmineralizationstudies,staticend-pointanalysisandsurfacecharacterizationiscommon,whilereal-timequantitationfocusingontimeofnucleation,nucleationrates,timeofcrystalgrowth,andgrowthrateshasnotbeenwidelyexplored.Abetterunderstandingoftheseparametersincoordinationwithstructuralanalysiscouldaidintheassessmentoftemplatemoleculesandcouldprovideinsightintobiologicalandbiomimeticmineralization.QCMisadynamic,real-timeanalyticaltechniquethatcanbegeneralizedtoavarietyofmineralsandcanbeintegratedwithwidelyusedsurfacecharacterizationtechniques.Asatemplateformineralization,DNAhasonlyrecentlybeenstudied,althoughithaspotentialasananionicpolynucleotidewithuniqueprogrammabilityandstructuraldiversityinfolding.专业英语复试题-3Livingorganismsarewellknowntoexploitthematerialpropertiesofamorphousandcrystallinemineralswhenbuildingawiderangeoforganic–inorganichybridmaterialsforavarietyofpurposes,suchasnavigation,mechanicalsupport,photonics,andprotectionofthesoftpartsofthebody.Thehighlevelofcontroloverthecomposition,structure,size,andmorphologyofbiomineralsresultsinmaterialsofamazingcomplexityandfascinatingpropertiesthatstronglycontrastwiththoseofgeologicalmineralsandoftensurpassthoseofsyntheticanalogues.[1]Itisnosurprise,then,thatbiomineralshaveintriguedscientistsformanydecadesandservedasasourceofinspirationinthedevelopmentofmaterialswithhighlycontrollableandspecializedproperties.InthisReviewweaimtoprovideanoverviewofthedifferentnature-drawnstrategiesthathavebeenappliedtoproducematerialsforbiomedical,industrial,andtechnologicalapplications.Wewillfirstillustratethediversityofbiogenicmineralsandtheiroverallproperties,anddescribethemostgeneralapproachesusedbyorganismstoproducesuchmaterials.Wewillthendiscussseveralapproachesinspiredbythemechanismsofbiomineralizationinnature,andhowtheycanbeappliedtothesynthesisoffunctionalandadvancedmaterialssuchasboneimplants,nanowires,semiconductors,andnanostructuredsilica.Inthefinalsection,wewilldiscussmethodsthatarenecessarytostudyandvisualizetheformationofsyntheticmaterialsinsitusoastobetterunderstand,control,andoptimizetheirsynthesisandproperties.专业英语复试题-4Nanoparticleswithdipoleormagneticmomentswillcreatelocaldipole/magneticfieldsandcanmutuallyattracteachotherincrystallographicregister.Thesameistrueforanisotropicparticlepolarization,whereparticlesurfaceswithequalpolarizabilityattracteachotherbydirectedvanderWaalsforces.Thisconceptrequiresthenucleationofalargenumberofnanoparticlesofaboutthesamesizewiththerequirementofanisotropyalongatleastonecrystallographicaxis.Thisanisotropycanalsobeinherenttothecrystalsystemaswasobservedforthecaseofaminoacidcrystalsormightbeinducedbyselectivepolyelectrolyteadsorptiontoexposehighlychargedfacessimultaneouslywiththeiroppositelychargedcounterface.AminoacidsareanidealsystemforthestudyofmesocrystalformationsincesimplepHvariationcanvarythecrystallizationpathbetweenclassicalandnonclassicalcrystallization,thesupersaturation,andcrystallizationspeedasdemonstratedforDL-alanine.Indeed,veryrecently,mesocrystalswerealsoobservedforthesamesystembyprecipitationinwater–alcoholsystems.