Determination and Temperature Dependence of Plateau Modulus for Polymerization of Propylene to Isotactic Polypropylene with Ultra-high Molecular Weight under Catalysis of Ziegler-Natta Catalyst

The viscoelastic behavior of isotactic polypropylene with ultra-high molecular weight (UHPPH) and broad molecular weight distribution(MWD), produced in the presence of Ziegler-Natta catalyst, was investigated by means of oscillatory rheometry at 180 and 200 ℃, whose loss modulus(G") plots at 180 and 200 ℃versus the natural logarithm of angular frequency(ω) present a pronounced maximum at 34.35 and 69.21 rad/s, respectively, and do not show a maximum peak at 0. 01-100 rad/s for Ziegler-Natta catalyzing ethylenepropylene random copolymerization (PPR) with a conventional molecular weight and broad MWD. The fact indicates that the high molecular weight is responsible for a maximum peak of G"(ω) vs. lnω curves for UHPPH. This makes it possible to determine the plateau modulus (G0N) of UHPPH from a certain experimental temperature G"(ω) curve directly. For UHPPH, the G0N determined to be 4. 28×105 and 3. 62×105 Pa at 180and 200 ℃, respectively, decreases with the increase of temperature and is independent of the molecular weight, which directly confirms reputation theoretical prediction that the G0N has no relation to the molecular weight.     

烷烃类分子对NCO(A2∑+)自由基的猝灭

采用激光光解-激光诱导荧光(LP-LIF)的方法,用266 nm激光光解CHBr3分子产生CH自由基,再与N2O继续反应作为NCO自由基的产生源,用438.6 nm激光将电子基态X2∏i(0010)的NCO激励到激发态A2∑+(00°0)上,通过检测激发态NCO时间分辨荧光信号,测得室温(298 K)下NCO(A2∑+)被烷烃类分子猝灭的实验结果,获得了A2∑+(00°0)态猝灭速率常数.实验发现,随着烷烃分子中C-H键数增加,其猝灭截面也近线性增加,但随着分子体积增大,这种增加趋缓.     

TWO PHOTONS EXCITED 4d RYDBERG STATE OF AsH3

In this paper, by using resonance enhanced (2+1) multiphoton ionization (REMPI) of AsH₃ and detecting the daughter molecular ions AsH⁺ and As⁺, a long progression discrete structure was obtained from 267 to 291 nm, which obeys the formula ν₀(cm^-1)=68875.3+504.1v′₂+5.26v′²₂. Analysis of the spectrum has revealed that it belongs to 4d Rydberg state transition. Our assignment yields the 4d Rydberg state parameters T_e′=67881.1 cm^-1, ω_e′=495.1 cm^-1 and δ=0.962. Finally the 4d Rydberg state structure of AsH₃ was discussed.     

CCl2自由基与H2O分子反应动力学研究

用213nm激光光解CCl4产生CCl2自由基,用LP-LIF技术测定了室温下基态CCl2自由基与H2O分子的反应速率常数为(5.45±0.95)×10-14cm3·molecule-1·s-1.在G2MP2理论水平上计算了CCl2+H2O反应的最低单重态势能面,揭示了插入与加成-消除两种反应机理,得到了三个可能的产物通道:HCl+HClCO、HCl+trans-ClCOH以及HCl+cis-ClCOH.并用RRKM-TST和传统过渡态理论计算了这三个通道的分支比及其温度效应.结果说明在低温下(273K),插入机理的产物通道的分支比远大于加成-消除机理的产物通道,HCl+HClCO是主要产物,分支比为77.4%,其次是HCl+cis-ClCOH,分支比为22.6%.而在高温下(3000K),加成-消除机理的反应通道大于插入机理,HCl+trans-ClCOH分支比为82.3%.     

A Quasi-Interpolation Satisfying Quadratic Polynomial Reproduction with Radial Basis Functions

In this paper,a new quasi-interpolation with radial basis functions which satis- fies quadratic polynomial reproduction is constructed on the infinite set of equally spaced data.A new basis function is constructed by making convolution integral with a constructed spline and a given radial basis function.In particular,for twicely differ- entiable function the proposed method provides better approximation and also takes care of derivatives approximation.     

Synthesis and Characterization of Poly(ether imide)s Containing m-Methyl and Phthalazinone Moieties

Aromatic polyimides are distinguished for their excellent mechanical and thermal properties in many engineering fields1. However, aromatic polyimides are normally insoluble in common organic solvents, which restricts their applications in some fields. Many efforts have been taken to improve their solubility. Introducing bulky side groups and non-coplanar structure into polymers bone chains is a good way to obtain the polymers with excellent mechanical and thermal properties2. In this paper…     

An Efficient and Green Procedure for the Preparation of gem-Dicar- boxylates from Aldehydes Catalyzed by Fe_2(SO_4)_3·xH_2O

~~An Efficient and Green Procedure for the Preparation of gem-Dicar- boxylates from Aldehydes Catalyzed by Fe_2(SO_4)_3·xH_2O~~     

氯代甲烷分子对电子激发态CH（A^2△,B^2Σ^—和C^2Σ^＋）的猝灭

本文用激光光解－荧光猝灭方法测定了ＣＨ３Ｃｌ对ＣＨ（Ａ，Ｂ和Ｃ）及ＣＨ２Ｃｌ２、ＣＨＣｌ３和ＣＣｌ４对ＣＨ（Ｃ）的猝灭速率常数。结果表明，氯代甲烷分子对ＣＨ（Ｃ）的猝灭速率常数近似于ＣＨ（Ｂ）的猝灭速率常数，而比ＣＨ（Ａ）的猝灭速率常数大，但都具有与气动速率相当的量线，表明化学反应在其中可能起着重要的作用，且ＣＨ（Ａ，Ｂ，Ｃ）的猝灭速率常数都随氯代甲烷分子中的Ｃ－Ｃｌ键数的增加而增大。我们用碰撞络     

A New Quantum State

１ＩｎｔｒｏｄｕｃｔｉｏｎＩｔｉｓｗｅｌｋｎｏｗｎｔｈａｔｂｏｓｏｎｒｅａｌｉｚａｔｉｏｎａｐｐｒｏａｃｈｉｓｖｅｒｙｅｆｅｃｔｉｖｅｔｏｓｔｕｄｙｔｈｅｒｅｐｒｅｓｅｎｔａｔｉｏｎｔｈｅｏｒｙｏｆｇｒｏｕｐ，ａｎｄｔｈｅｂｏｓｏｎｒｅａｌｉｚａｔ...     

Comparison of the Contributions of Tetrahydrofurfuryl Alcohol and PEG to a-Chymotrypsin Renaturation with High Performance Hydrophobic Interaction Chromatography

Theinvestigationofproteinrenaturation,orrefoldinghasbecomeaveryhotpointinbothliquidchromatography(LC)andlifesciencefields.Besidesusualdilutionanddialysismethods,manynewmethodsconcernproteinrenaturationhavebeenpresented,suchasreversemicelles1,chaperones2,polyethyleneglycol(PEG)3,surfactant4andantibodies5etc.Oneoftheauthorssuggestedhighperformancehydrophobicinter-actionchromatography(HPHIC)tobeanewtoolforproteinrenaturation6.Areviewonproteinrenaturationwithliquidchromatography(LC)wasrecentl…