简介:Moleculardynamics(MD)simulationswereperformedtostretchtherectangulargraphenesheetsdopedwithsilicon,nitrogenorboronatoms.Young’smodulus,ultimatestress(strain)andenergyabsorptionweremeasuredforthegraphenesheetswiththedopingconcentration(DC)rangingfrom0to5%.Theemphasiswasplacedonthedistincteffectsofeachindividualdopantonthefundamentalmechanicalpropertiesofgraphene.TheresultsindicatedthatincorporatingthedopantsintographeneledtoanalmostlineardecreaseinYoung’smodulus.Monotonicreductionsinultimatestrength,ultimatestrainandenergyabsorptionwerealsoobserved.Suchdopingeffectswerefoundtobemostsignificantforsilicon,lesspronouncedforboron,andsmallornegligiblefornitrogen.Theoutputsprovideanimportantguidanceforthedevelopmentandoptimizationofnovelnanoscaledevices,andfacilitatethedevelopmentofgraphene-basedM/NEMS.
简介:Ultrafast各向异性的腐烂是揭示ultrafast精力和电子转移的一个突出的参数;然而,由于平行和垂直极化的腐烂动力学的同时的可获得性的要求可靠地坚定是困难的。现在,各向异性的腐烂的任何测量是准确同时性的一种途径。这里,我们为同步ultrafastanisotropy腐烂大小报导一个新奇方法,它能很好决定anisotropy,甚至在一很早的时间,作为刺激激光脉搏的升起的阶段。在与协调刺激在房间温度在答案收获Rhodobactersphaeroides的天线建筑群LH2的细菌的光的B850的各向异性的腐烂被这个方法检测,它显示出30fs的一极化反应时间,并且到在B850戒指的bacteriochlorophylls的从起始的刺激的精力转移拿大约70fs。在吸收光谱的红方面被探查的各向异性的腐烂例如880nm,有0.4的起始的价值,相应于模仿的排放,当有0.1的anisotropy的蓝方面贡献漂白的地面状态时。我们的结果证明盖住整个戒指的协调刺激可能没由于LH2碎的对称被认识到:从在到在答案的C2对称的膜的C9对称。
简介:Theoreticalmodelsofstellarevolutionpredictnegligiblequantitiesof6Li,9Be,and11Binthehydrogenburningphasesofastar’sevolution[1].TheprimordialBig-Bangnucleosynthesis(BBN)modelmightbemoregenerousinitsproductionoftheseelements[2].Theradiative-capturecrosssectionforprotoncaptureon11Bleadingto12CissmallatastrophysicallyinterestingenergiesbecauseofthelargeCoulombbarrier.
简介:4-(Succinimido)-1-butanesulfonicacidasanefficientandreusableBronstedacidcatalyzedthesynthesisofpyrano[4,3-b]pyranderivativesundersolvent-freeconditions.Thecatalystcanbepreparedbymixingsuccinimideand1,4-butanesultonethatismoresimpleandsaferthanthepreparationofsuccinimidesulfonicacid.Thismethodhastheadvantagesofhighyield,cleanreaction,simplemethodologyandshortreactiontime.Thecatalystcouldberecycledwithoutsignificantlossofactivity.
简介:标题化合物(C24H16N4S)以噻吩-2-甲醛、苯甲酰乙腈和3-甲基-1-苯基-1H-吡唑-5-胺为原料,在离子液体[bmim]Br溶剂中,在80℃搅拌合成得到.其结构通过单晶X射线衍射法确定,晶体属于三斜晶系,空间群P-1,相对分子质量Mr=392.47,晶胞参数a=0.93612(8)nm,b=1.03063(12)nm,c=1.16624(16)nm,V=0.96853(19)nm3,Z=2,晶胞密度Dc=1.346g/cm3,吸收系数μ=0.185mm-1,单胞中电子的数目F(000)=408.晶体结构用直接法解出,经全矩阵最小二乘法对原子参数进行修正,最终的偏离因子R=0.0585,wR=0.1337.在晶体结构中新形成的吡啶环与吡唑环近似于共平面结构.