简介:ThechoicenumberofagraphG,denotedbyX1(G),istheminimumnumberksuchthatifalistofkcolorsisgiventoeachvertexofG,thereisavertexcoloringofGwhereeachvertexreceivesacolorfromitsownlistnomatterwhatthelistsare.Inthispaper,itisshowedthatX1(G)≤3foreachplanegraphofgirthnotlessthan4whichcontainsno6-,7-and9-cycles.
简介:AseriesofdoubleperovskitesRSrMnFeO_6(R=La,Pr,Nd,Sm)wassynthesizedundermildhydrothermalconditions.Crystalgrowthsofthesamplesweresensitivetoalkalinity,temperature,fillingfraction,andcompositionofinitialreactionmixture.ThedesiredseriesofcompoundsbelongstotheclassofAA'BB'O_6perovskiteswitharandomdistributionofMnandFeatomsovertheB-cationsub-lattice.TheirstructuresshowthedistortedorthorhombicsymmetrywithspacegroupPnma.TheshapesandsizesofthecrystalswereanalyzedonaRigakuJSM-6700Fbyscanningelectronmicroscopy.AnalysisdonebyXPS,MssbauerspectroscopyandiodometrictitrationrevealsthatMnandFeionshave+4and+3oxidationstates,respectively.
简介:Onenewsesquiterpenecompound,namely,illihenlactoneA(1),andonenewprenylatedC6–C3compound,illihenryioneH(2),alongwiththreeknownsesquiterpenes(3–5)wereisolatedfromthestemsofIlliciumhenryi.Thestructuresof1and2wereelucidatedbyspectroscopicevidenceincludingNMR,HRESIMSandcirculardichroism(CD).Compound2exhibitedaweakinhibitoryratioforbglucuronidasereleaseinducedbyplatelet-activatingfactor(PAF)inratpolymorphonuclearleukocytes(PMNs)invitro.
简介:Ti6Al4Visawidelyappliedinmedicalimplantssuchasbone,joint,andteethduetoitsexcellentmechanicalproperties,corrosionresistance,plasticityandthebiocompatibilityofthesurfaceoxide.However,thenativesurfaceoxidefilmisquitethin(about5nm)andtechniquessuchasmicroarcoxidation,plasmasprayedhydroxyapatitaeandplasmaimmersionionimplantationareusedtosynthesizethickersurfacetitaniumoxide.
简介:TheCADSdemofacilityisaimedtobuildaprototypelinacforthelowenergypartofthecontinuouswave(CW)superconductingprotonlinacanddemonstratetechnologyinthissection[1].IntheCADSroadmap,therealizationof25MeV10mAbeamisakeypoint.Thus,basedonthe10MeVCADSInjectorIIatIMP,IMPandIHEPwillbothcontributeacryomoduletoreach25MeVatthesiteofIMP[2].Todumpthebeamfromthelinac,webuildanewhighenergybeamtransportlinewithbendingangleof90°,toavoidback-scatteringgammaandneutronbeamstodamagethelinac.Fig.1showsthelayoutofthe25MeVdemofacility.
简介:Inthiswork,SMAT(surfacemechanicalattritiontreatment)wasperformedonTi6Al4V.PlasmanitridingoftheSMATedsampleswasinvestigatedincomparisonwithcoarse-grainedsamples.Thesampleswerecharacterizedusingopticmicroscope,SEM,TEMandVickersmicrohardnesstester.TheresultsshowedthatasignificantlythickercompoundlayerwithhigherhardnesswasobtainedfortheSMATedsampleswhencomparedwithun-SMATedsamplesafternitriding.CorrosionresistanceofTi6Al4VinaRinger’ssolutionwasstudiedbyelectrochemicaltechniquesincludingopencircuitpotentialmeasurement,potentiodynamicpolarizationandEIS(electrochemicalimpedancespectroscopy).Overall,ourresultsidentifiedthebeneficialimpactsoftheduplexSMAT/nitridingtreatmentoncorrosionbehaviourofTi6Al4V.Weartestswerealsoperformedonaball-on-disctribometerwherethetreatedsampleswererubbedagainsta6mmdiameteraluminaballunderanormalloadof5NusingRinger’ssolutionaslubricantmedia.ThefrictioncoefficientoftheSMATedandnitridedsampleswasreducedcomparedtotheuntreatedsamples.WearratesdemonstratedthatSMATcombinedwithnitridingimprovedwearresistanceofTi6Al4Valloy.
简介:Segmentedblockcopolymerbasedonnylon6(N6)andpolyethyleneoxide(PEO)withstochiometricratiowassynthesizedviaatwo-stepprocess.ThefirststeprepresentsendcappingofN6inthepresenceofadipicacidleadingtocarboxyterminatedN6,andthesecondoneispolycondensationofthelatterproductwithPEOinthepresenceofcatalystandthermostabilizertoformahighmolecularweightmulti-blockcopolymer.SeveralmethodswereappliedtocharacterizethesynthesizedcopolymersuchasFouriertransforminfraredspectroscopy,protonnuclearmagneticresonancespectroscopy,differentialthermalanalysis,differentialscanningcalorimetry,X-raydiffractionandatomicforcemicroscopy.Theobtainedresultsconfirmedthemulti-blockstructureforcopolymerwithaveryhighdegreeofmicro-phaseseparation.Atomicforcemicroscopymicrographsindicatedthatthemorphologywasthedispersionofhighstiffnessnanostructuredpolyamide(PA)domainsintheamorphousregionofPEOmatrix,whichcanbeveryimportantintheirperformanceformembraneprocesses.
简介:Inanattempttofindnewantitumoragents,anovelclassofchromonecompoundswithabenzimidazoleorabenzoxazoleringinpositions2or6weresynthesizedviacondensationinpolyphosphoricacid(PPA)byusingchromoneacidsasthestartingmaterials.Duringthepreparationprocess,itwasfoundthatPPAcouldcleavethechromoneringtoproducearing-openingcompound(6).Themolarratioofthechromonecompound(5)tothering-openingcompound(6)variedwiththechangeofreactiontemperatureandtime.BasedonMTTprotocol,theantitumoractivityofeachofthecompoundsobtainedwasevaluatedagainstthreehumancancercelllines:KB(oralepidermal),A2780(ovary)andBel7402(liver).TheIC50variedfrom54.7μmol/Ltomorethan180μmol/L.