Microscopic description of the real alpha-nucleus potenial at large distances

The real part of the alpha-nucleus potential is calculated by double folding shell-model matter distributions of the projectile and target nuclei with effective nucleon-nucleon potentials obtained either phenomenologically, or microscopically from the Reid soft-core potential. Comparisons are made with experimental alpha-scattering data at incident energies near the Coulomb barrier, where effects due to the imaginary potential at large distances are negligibly small. The range of the effective nuclon-nucleon force at intermediate distances and the effective nucleon-alpha interaction are investigated.     

Ion implantation in III–V compounds

In this work we studied the effect of electron and proton irradiation on the depth distribution of sodium in commercial soda-lime glasses. Samples have been irradiated at different energies and fluences.

The ²³Na (ρ, α) ²⁰Ne nuclear reaction has been used to determine the sodium profiles. No detectable changes in the sodium concentration profiles have been introduced during the measurements, the proton fluences and doses needed in this type of analysis being very low.

The obtained results support the hypothesis that the driving force for Na diffusion is mainly connected to the build-up of an electric field whose direction is determined by the projectile charge, while Na mobility changes because of the local temperature increase due to the beam power dissipation.     

Copolymerizations of propylene with functionalized long‐chain α‐olefins using group 4 organometallic catalysts and their membrane application

Introduction of functional groups into polyolefins has the potential of broadening their end use. An attractive method for preparing polyolefins containing functional groups is the copolymerization of the olefins with α‐olefins containing a functional group. Copolymerizations of propylene with 10‐undecen‐1‐ol, containing a hydroxyl group protected by either TIBA or TBDMSCl, 11‐chloro‐1‐undecene, 5‐bromopent‐1‐ene and N‐allyl‐2,2,2‐trifluoroacetamide were performed using three organometallic catalysts: the metallocene rac‐Et(Ind)₂ZrCl₂ and two new benzamidinate catalysts [3‐C₅H₄NC(NSiCH₃)₂]₂TiCl₂ and [(m‐OMe‐C₆H₄NC(NSiCH₃)₂]₂ZrCl₂. 10‐Undecene‐1‐ol protected “in situ” with TIBA and N‐(dec‐9‐enyl)‐2,2,2‐trifluoroacetamide gave copolymers with similar polar monomer incorporation percentages and molecular weights 17%; 28,900 g/mol for the protected 10‐undecene‐1‐ol, and 15%; 27,100 g/mol for N‐(dec‐9‐enyl)‐2,2,2‐trifluoroacetamide. 11‐Chloro‐1‐undecene gave copolymers with up to 22% incorporation for 0.12 M of the comonomer in the reaction feed. The obtained copolymers were characterized by NMR, DSC, and GPC. Membranes were prepared from two copolymers containing the hydroxyl groups (6 and 10%) and one copolymer containing chlorine groups (7%). The membranes prepared could be wetted in contrast to polypropylene membranes which do not contain functional groups. In addition, it was observed that for both type of membranes prepared from the different copolymers containing the hydroxyl groups, the flux was significantly greater than for the membrane prepared from the copolymer containing a chlorine groups. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011     

Organoactinides promote the dimerization of aldehydes: scope, kinetics, thermodynamics, and calculation studies

Surprising catalytic activities have been found for the actinide complexes Cp*(2)ThMe(2) (1), Th(NEtMe)(4) (2), and Me(2)SiCp'(2)Th(C(4)H(9))(2) (3) toward oxygenated substrates. During the catalytic dimerization of benzaldehydes to their corresponding esters, complexes 1 and 2 gave 65 and 85% yield in 48 h, respectively, while the geometry-constrained complex 3 gave 96% yield in 24 h. Exploring the effect of substituents on benzaldehyde, it has been found that, in general, electron-withdrawing groups facilitate the reaction. Kinetic study with complexes 1 and 3 reveals that the rate of the reaction is first order in catalyst and substrate, which suggests the rate equation "rate = k[catalyst](1)[aldehyde](1)". The activation energy of the reaction was found to be 7.16 ± 0.40 and 3.47 ± 0.40 kcal/mol for complexes 1 and 3 respectively, which clearly indicates the advantage of the geometry-constrained complex. Astonishing are the reactivity of the organoactinide complexes with oxygen-containing substrates, and especially the reactivity of complex 3, toward the dimerization of substrates like p-methoxybenzaldehyde, m/p-nitrobenzaldehyde, and furanaldehyde and the reactivity toward the polymerization of terephthalaldehyde. Density functional theory mechanistic study reveals that the catalytic cycle proceeds via an initially four-centered transition state (+6 kcal/mol), followed by the rate-determining six-centered transition state (+13.5 kcal/mol), to yield thermodynamically stable products.     

Vapour—liquid equilibrium T—x measurements by a new semi-micro method

A semi-micro method for determining the boiling temperature of a liquid mixture using a thermistor is described. Boiling temperatures of the binary mixtures n-heptane—toluene, toluene—n-octane and 1-n-octene—n-octane were determined as functions of the composition. The isobaric T—x values were used to compute equilibrium vapour composition by numerical integration of the Duhem—Margules equation. The T—x—y values are presented at 101325, 79993 (or 85326), 53329 and 26664 Pa.     

Measurement of nuclear deformation parameters from elastic and inelastic scattering of α and 3He ions on Te isotopes

Cross sections for the elastic scattering of ⁴He by ^{122, 124, 126, 128}Te and ³He by ¹²⁸Te and for inelastic transitions to the lowest 2⁺ states of Te isotopes were measured for several scattering angles at bombarding energies in the vicinity of the Coulomb barrier. The data were analyzed in the framework of the optical model and the DWBA from which optical potential and deformation parameters were extracted. A detailed study of the fit procedure is presented with emphasis on the significance of the extracted parameters and the correlations among them.     

Capillary gas chromatography of C6−C14 n-alkenes on polyphenyl ether and polyethylene glycol 4000

Summary The retention indices (I) and their structural increments (l/°C, H, l) of C₆–C₁₄ n-alkenes on polyphenyl ether (PFE) and C₁₂–C₁₄ n-alkenes on polyethylene glycol 4000 (PEG) at 20–160 °C have been determined and correlated with the molecular structure of the isomers. A number of common regularities in gas chromatographic behaviour on these liquid phases and squalane (SQ) [1–3] have been found. On PFE the elution order of isomeric n-alkenes is similar to that on SQ (except C₈–C₁₀ 1-alkenes and cis-4-tetradecene), for pairs with cis- and trans-configuration it depends on the column temperature, position of double bond and the number of carbon atoms (n) in the molecule. On PEG the cis- are always retained longer than the corresponding trans-alkenes. The linear relationships between 1 and n on PFE and PEG are given in equation form.     

Die Druckabhängigkeit der Siedetemperaturen der stellungs- und konfigurationsisomeren n-Octene,n-Nonene und n-Decene

The boiling points of unbranched C₈?C₁₀ alkenes were determined by an ebulliometric method at the following pressures: 200, 300, 400 and 600 torr and at atmospheric pressure. The equipment used is described and the results obtained presented in tabular form. The constants of theAntoine equation and the normal boiling points were calculated.     

Thermodynamische Untersuchungen ann-Alkan/n-Alkin-Systemen

Heats of mixing (H ^E)ofn-octane with 1,2,3,4-isomers ofn-octyne,n-heptane withn-1-heptyne andn-nonane withn-1-nonyne at temperatures from 298.15 to 318.15 K were measured with aCalvet-type microcalorimeter. The results are presented in tables and correlated with theRedlich-Kister equation.