简介:Thesuccinylationofcornstarchbyslurryreactionhasbeenstudiedusingsodiumhydroxideascatalyst.SeveralreactionparametersafJectingthesuccinylationwereinvestigatedincludingtheconcentrationofstarchinwater,theratioofsuccinicanhydridetostarch,thereactiontimeandthereactiontemperature.Thefavorableconditionsforanintermediatedegreeofsubstitution(DS)andreasonablyhighreactionefficiency(RE)arepH8.5~9.0,50%starchbyweighttowater,succinicanhydridetostarchI/I(w/w),reactiontime4h,reactiontemperature30℃Undertheseconditions,theDSof0.45andREof28%wereachieved.Theadditionofanadequateamountofcrosslinkingagentimpartedstarchsuccinatewaterabsorbency.
简介:ApplyingperturbativeQCD,westudytheprocessBc→Dsγinthetechnicolorwithamasslessscalardoubletmodel(TCMLSM).TherearemainlytwomechanismscontributingtotheBc→D*sγprocess.Oneproceedsthroughtheshortdistanceb→sγtransitionandtheotherthroughweakannihilationaccompaniedbyaphotonemission.Wefindthat,comparedwiththestandardmodel,themodificationofBc→D*sγfromπρ(thephysicalpionsintheTCMLSM)issosmallthatcanbeneglectedfortheallowedmassofπρ.Theweak-annihilationcontributionisfoundtobeaboutoneorderlargerthanthatoftheelectromagneticpenguindiagrams.
简介:在网络终端视频体验过程中,影响用户体验的两个关键指标为初始缓冲等待时间和卡顿缓冲时间,本文结合移动视频传输协议等相关知识,通过机理分析方法,对实验数据进行分析和挖掘,建立了初始缓冲时延映射模型与卡顿时长占比函数模型。并基于视频体验评分测试软件Speedvideo及其网络运营平台,对所在地多个区域进行了综合测试。
简介:在加热条件下,发现氯化铵可以使季戊四醇单侧修饰的Anderson型铬钼酸盐发生结构变异,Anderson型多酸母体上的季戊四醇配体由正中心位置异构到非正中心位置(季戊四醇配体的一个烷氧基从取代多酸骨架中的μ3-O桥氧原子异构为取代骨架中的μ2-O桥氧原子),得到其χ同分异构体(NH4)3{χ-[Cr(OH)3Mo6O(18)(OCH2)3CCH2OH]},并通过电喷雾质谱ESI、红外光谱IR和单晶X射线衍射的方法确定了该化合物的结构.晶体测定及分析结果表明,该化合物属单斜晶系,P21/n空间群,晶胞参数a=1.05368(4)nm,b=2.91172(6)nm,c=1.12470(7)nm,α=90°,β=117.45(6)°,γ=90°,Z=4,V=3.0621(3)nm3.