简介:利用MP2和mPWPW91方法,在6-311G**和6-311++G**基组水平上研究了RDX分别与硝基、氨基和迭氮基取代的氮杂杯[2]-间-芳烃[2]三嗪和氮杂杯[2]-对-芳烃[2]三嗪形成的分子间氢键相互作用,并借助自然键轨道(NBO)和分子中的原子(AIM)理论揭示了氢键的本质.结果表明,氮杂杯[2]-间-芳烃[2]三嗪复合物中氢键主要发生在RDX与三嗪环及其取代基之间;氮杂杯[2]-对-芳烃[2]三嗪复合物中氢键主要发生在RDX与杯芳烃环及其取代基之间.分子间相互作用能在-18.82--40.62kJ/mol之间;经基组叠加误差(BSSE)校正后,相互作用能顺序为e〉f≈b〉a〉c〉d和e′〉b′〉f′〉a′〉d′〉c′.两类复合物中,氨基取代的复合物分子间氢键强于硝基或叠氮基复合物分子间氢键,氨基氮杂杯[2]-对-芳烃[2]三嗪与RDX形成的氢键最强,有望作为降低火炸药感度、进行火炸药废水处理的候选物.为获得稳定性较强的RDX-氨基氮杂杯芳烃超分子炸药,应该选取介电常数较大的溶剂.
简介:Ahighlyeffcientandgeneralmethodforthesynthesisofpolyfunctionalized4H-pyransisestablishedthroughaone-potmulticomponentcyclocondensationofaromaticaldehydeswithCHacids,malononitrileandethylacetoacetateusingnanosilicasupportedtin(II)chlorideasacatalyst.InthismethodSnCl2/nanoSiO2wasusedasgreenandreusablecatalyst.Excellentyields,shortreactiontimes,simpleworkup,andinexpensivenessandcommerciallyavailabilityofthecatalystaretheadvantagesofthismethod.
简介:Rare-earthcompoundsolidsuperacidSO42-/TiO2/La3+wasprepared.Itscatalyticactivitywasexaminedunderdifferentsyntheticconditionsfortheesterificationofpropanoicacidandn-butylalcoholasprobingreaction.Theoptimumconditionswerealsofound,whichwerethepH=8,thedepositingtimewas24h,themassfractionofLa(NO3)3usedinsolidsuperacidwas5%,theconcentrationofH2SO4was1.25mol/L,thesoakingtimeinH2SO4was16handthecalciningtemperaturewas500°C.TheethyloleatewassynthesizedfromoleicacidandethanolinthepresenceofSO42-/TiO2/La3+.Theoptimumreactionconditionswereobtainedwhichwerethereactiontimewas6h,molarratioofoleicacidtoethanolwas1:4andthemassfractionofcatalystwas4%.
简介:MakinguseoftheZ2×Z2symmetry,wecouldstudythestructurenearmultipleS-treakingturningpoints.Inparticular,weshowthatthereexisttwokindsofsingularpointpaththroughdoubleSbreakingturningpointsandtripleSbieakingturningpoints,onetsquadraticturningporntpathandoneisquadraticpitchforkbifurcationpointpath.SomesimpleregularextendedsystemstocornputedoubleandtripleS-breakingturningpointsareproposed.Numericalexamplesarealsogreen
简介:AgraphGiscalledchromatic-choosableifitschoicenumberisequaltoitschromaticnumber,namelych(G)=χ(G).Ohba’sconjecturestatesthateverygraphGwith2χ(G)+1orfewerverticesischromaticchoosable.ItisclearthatOhba’sconjectureistrueifandonlyifitistrueforcompletemultipartitegraphs.Recently,Kostochka,StiebitzandWoodallshowedthatOhba’sconjectureholdsforcompletemultipartitegraphswithpartitesizeatmostfive.Butthecompletemultipartitegraphswithnorestrictionontheirpartitesize,forwhichOhba’sconjecturehasbeenverifiedarenothingmorethanthegraphsKt+3,2*(k-t-1),1*tbyEnotomoetal.,andKt+2,3,2*(k-t-2),1*tfort≤4byShenetal..Inthispaper,usingtheconceptoff-choosable(orL0-size-choosable)ofgraphs,weshowthatOhba’sconjectureisalsotrueforthegraphsKt+2,3,2*(k-t-2),1*twhent≥5.Thus,Ohba’sconjectureistrueforgraphsKt+2,3,2*(k-t-2),1*tforallintegerst≥1.
简介:TheapplicationofLanthanumBromide(LaBr3)detectorsprovidesauniqueopportunitytomeasurelifetimeofexcitedstatesinpicosecond-nanosecondregion.Reducingthebackgroundisofcriticalimportancetogetpreciseresults.Forsomeexcitedstatesfeedingfromisomerswithlifetimelongerthan1μs,itcanbeachievedbytheSpectrometerforHeavyAtomandNuclearStructure(SHANS)[1].143Eunucleiwerepopulatedviathe123Sb(24Mg,4n)fusion-evaporationreaction.Mostoftheevaporationresiduesatgroundstateorlong-livedisomersweretransferredtodetectionterminalafteraflightofabout1.4μsinSHANS.Inthecaseof143Eu,threetransitionshavebeenobserved(Fig.1).
简介:TiO2nanoparticlesweresynthesizedbyahomogeneouscontrolledprecipitationmethodusingindustrialtitaniumsulfate(Ti(SO4)2).TheobtainedpowderswerecharacterizedbyX-raydiffraction(XRD),transmissionelectronmicroscope(TEM),Fouriertransforminfraredspectroscopy(FTIR)andICPplasmaspectrometer.EDTAwasusedascomplexingagenttoimprovethepurityandtheformationofTiO2nanoparticles.Experimentalresultsindicatedthatthehigh-purityTiO2nanoparticleswere20nminmeansizeandnearlymonodispersed.
简介:Inthispaperwereportachemicaloscillationcatalyzedby[Ni(Me2[14]1,3-dieneN4)]2+(Me2[14]l,3-dieneN4denotes2,3-dimethyl-l,4,8,ll-tetraazacyclotetradeca-1,3-diene)inBrO3--pyruvicacid-H2SO4system.Thedomainoftheexistenceoftheoscillationwasobtained.Theeffectsofinitialconcentrationofthecomponentsontheoscillationwerestudied.Thefeaturesoftheoscillationsweredescribedindetail.WealsoexaminedtheeffectsofAg+,Hg2+,CCl4,freeradicalinhibitors,etc.ontheosillations.
简介:QuantumdynamicscalculationsforthetitlereactionH(2S)+S2(X3-Σg)→SH(X2Π)+S(3P)areperformedbyusingagloballyaccuratedoublemany-bodyexpansionpotentialenergysurface[J.Phys.Chem.A1155274(2011)].TheChebyshevrealwavepacketpropagationmethodisemployedtoobtainthedynamicalinformation,suchasreactionprobability,initialstate-specifiedintegralcrosssection,andthermalrateconstant.Itisfoundnotonlythatthereisareactionthresholdnear0.7eVinbothreactionprobabilitiesandintegralcrosssectioncurves,butalsothatboththeprobabilityandcrosssectionincreasefirstlyandthendecreaseasthecollisionenergyincreases.Theexistenceoftheresonancestructureinboththeprobabilityandcrosssectioncurvesisascribedtothedeeppotentialwell.Thecalculationoftherateconstantrevealsthatthereactionoccurringonthepotentialenergysurfaceoftheground-stateHS2isslowtotakeplace.
简介:SYNTHESISANDANTI-HUMANIMMUNODEFICIENCYVIRUS-1(HIV-1)ACTIVITYOF9-(2-PHOSPHONYLMETHOXYETHYL)ADENINE(1)ANDITSREGIOISOMER3-(2-PHO...
简介:PureAl2O3-2SiO2powderswerepreparedbysol-gelandcoprecipitationmethods,andtheiralkaliactivationreactivitieswerecompared.Thealkali-activationreactivityofthepowderpreparedbythesol-gelmethodwashigherthanthatofthepowderpreparedbythecoprecipitationmethod.Thepowderswereinvestigatedby27AIand29Simagic-anglespinningnuclearmagneticresonancespectroscopy(MASNMR)tounderstandtherelationshipbetweentheirstructureandalkali-activationreactivity.The27AlMASNMRdatashowedthatthefive-coordinateAIcontentofthepowderpreparedbythesol-gelmethodwashigherthanthatofthepowderpreparedbycoprecipitation.Thehighercontentoffive-coordinateAlcorrespondedtohigheralkali-activationreactivity.The29SiMASNMRdatashowedthatforthepowderpreparedbythesol-gelmethod,siliconwasreplacedbyaluminumatsecondarycoordinationsitesofthecentralSiatomsduringcalcination.However,forthepowderpreparedbysingle-batchcoprecipitation,themainchangewasfromalowdegreeofpolycondensationtoahighdegreeofpolycondensation.
简介:采用铜(Ⅱ)盐和3,5-二氯水杨醛缩丝氨酸以及4,4′-联吡啶在乙醇水溶液中合成了具有二维层状的配位聚合物.通过元素分析、红外光谱对该配位聚合物进行了表征,并利用X射线单晶衍射仪对其结构进行了鉴定.晶体结构表明,该标题配合物属三斜方晶系,空间群C2/c,晶胞参数为a=2.711(3)nm,b=2.711(3)nm,c=4.977(5)nm;α=90.00°,β=90.00°,γ=120.00°,V=3.1678nm^3,Z=18,Dc=1.173g·cm^-3,F(000)=11448,μ=0.807mm-1,R1=0.0788,wR2=0.1872.
简介:LiuandYangavethedegreeconditionforabalancedbipartitegraphG=(V_1,V_2;E)tohavekvertex-disjointquadrilateralscontaininganygivenkindependentedgese_1,...,e_kofG,respectively.Theyalsoconjecturedthatforanykindependentedgese_1,...,e_kofG,Ghasa2-factorwithkcyclesC_1,C_2,…,C_kwithrespectto{e_1,e_2,...,e_k}suchthatk-1ofthemarequadrilaterals.Inthispaper,weprovethisconjecture.
简介:Therearetwokindsofchargingmodeoftheohmpowersupply.Whenthedeviceworksnormallyandtheplasmabreakdownvoltageislow,theohmpowersupplywillruninthelogicalnon-loopcurrentmodewhichcurrentissymmetrical,butwhenthedischargingconditionisnotverywellandtheplasmabreakdownvoltageishigh,theunsymmetricalmodewillbeadopt,i.e.switchingoffthepositiverectifier,