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121.
The enthalpy relaxation mechanism of a low molecular weight synthesis of polymethylmethacrylate was investigated by means of calorimetric experiments. The data were analyzed in terms of a kinetic approach treating nonlinearity in a different manner with respect to the Tool-Narayanaswamy-Moynihan model. The relaxation isotherms recorded at four different temperatures were well reproduced by this approach that, however, failed in describing the relaxation asymmetry towards the equilibrium after opposite temperature jumps. A modification of the model was proposed with an additional free parameter accounting for the stretching of the relaxation function. In this way all the experimental data were reproduced fairly well. 相似文献
122.
L. Gialanella F. Strieder L. Campajola A. D'Onofrio U. Greife G. Gyurky G. Imbriani G. Oliviero A. Ordine V. Roca C. Rolfs M. Romano D. Rogalla C. Sabbarese E. Somorjai F. Terrasi H.P. Trautvetter 《The European Physical Journal A - Hadrons and Nuclei》2000,9(3):303-305
The absolute cross section σ (E) of the radiative capture reaction p(7Be,γ)8B at the center-of-mass energy E = 992 keV has been measured using a radioactive 7Be ion beam and a windowless gas target system filled with H2 gas. The 8B residual nuclides were detected with a recoil separator consisting of momentum and velocity filters and a ΔE-E detector
telescope. The 8B yield was observed concurrently with the 7Be + p elastic scattering yield, relating σ(E) to the Rutherford scattering cross section. The resulting value, σ(E) = 0.41
± 0.11 μb, leads to an S(E) factor at zero energy of S(0) = 16 ± 4 eV b, in fair agreement with recommended values.
Received: 8 February 2000 相似文献
123.
M. Sandoli A. Boiano L. Campajola A. De Rosa A. D'Onofrio G. Inglima M. La Commara A. Ordine D. Pierroutsakou V. Roca M. Romano M. Romoli M. Trotta F. Rizzo F. Amorini S. Tudisco 《The European Physical Journal A - Hadrons and Nuclei》1999,6(3):275-288
We report on the results obtained from the study of the 32S +74Ge deep inelastic reaction at incident energy E= 320 MeV. High-energy γ-rays were detected in an array of 6 seven-pack BaF2 clusters. Coincidence with complex fragments detected in 12 three-stage telescopes ensured the selection of peripheral reaction
events. In order to investigate the pre-equilibrium dipole strength excitation two independent analyses were performed. In
the first analysis the energy spectra of the γ-rays were evaluated in the statistical model framework while in the second
one the γ-ray fragment angular correlation with respect to the nuclear spin vector of the composite system was studied. Both
methods indicate the excitation of dipole strength in the highly deformed dinucleus and provide dipole resonance parameter
sets that are in good agreement with each other.
Received: 24 March 1999 / Revised version: 17 May 1999 相似文献
124.
E. Costanzo A. Cunsolo A. Foti O.Yu. Goryunov M. Lattuada V.V. Ostashko L. Putaggio S. Romano C. Spitaleri A. Tumino D. Vinciguerra Yu Xian 《The European Physical Journal A - Hadrons and Nuclei》1999,5(1):69-75
8Begs coincidences with 12C, 8Begs and α-particles produced in the 12C +12C interaction at 65 MeV have been measured in a wide in-plane angular range. The 3 −8Begs final state is found to be produced, even if poor statistics prevent any identification of the 16O states involved in the first stage of the process. The 8Begs−α and 8Begs−12C coincidence yields are found to be due to 12C and 16O excited states, decaying into the 8Begs+α and 12C +α systems, respectively.
Received: 15 June 1998 / Revised version: 4 December 1998 相似文献
125.
M. Auf der Maur F. Sacconi G. Penazzi M. Povolotskyi G. Romano A. Pecchia A. Di Carlo 《Optical and Quantum Electronics》2009,41(9):671-679
Multiscale methods coupling quantum mechanical/atomistic models such as envelope function and tight binding approaches with continuous media models e.g. for strain or electronic transport are very useful for an accurate simulation of modern and emerging electronic and optoelectronic devices based on nanostructured active regions. We present simulations using TiberCAD whose main focus is on providing an integrated multiscale/multiphysics simulation environment. 相似文献
126.
Diana Amorello Fabrizio Ledda Vincenzo Romano Roberto Zingales 《Journal of solution chemistry》2009,38(2):259-263
The determination of the Ti(IV,III) redox couple formal potential in 1 mol⋅dm−3 HCl, 2 mol⋅dm−3 NaCl medium at 25 °C through batch experiments involving the preparation of Ti(IV) and Ti(III) mixtures via the reaction
of Ti(IV) with zinc amalgam, has been carried out with Emf measurements in order to verify the correctness of the previous
value that the authors obtained by a coulometric-potentiometric investigation in the same conditions. The results from the
two independent methods are in good agreement: (9±1) mV by the first method and (9±2) mV by the average batch result. 相似文献
127.
Romano Gatto 《Mathematical Intelligencer》2009,31(2):80
Stamp CornerRobin Wilson
The Philamath’s Alphabet−WXYZ 相似文献128.
Carçabal P Hünig I Gamblin DP Liu B Jockusch RA Kroemer RT Snoek LC Fairbanks AJ Davis BG Simons JP 《Journal of the American Chemical Society》2006,128(6):1976-1981
The intrinsic conformer specific vibrational spectra of two important subunits of the core pentasaccharide of N-linked glycans, the alpha(1,3) and alpha(1,6) dimannosides, have been recorded in the gas phase. Coupling these measurements with a computational exploration of their conformational landscapes has enabled their conformational assignment and has identified characteristic vibrational signatures associated with particular conformational families-including those that do or do not display inter-ring hydrogen bonding across the glycosidic linkage. In addition, the IR spectra of the monosaccharide moieties provide benchmarks, through which the conformational assignments can be refined. This introduces a general concept of modularity and secondary structure in oligosaccharides--essential for the success of similar studies on larger oligosaccharides in the future. 相似文献
129.
Vugts DJ Koningstein MM Schmitz RF de Kanter FJ Groen MB Orru RV 《Chemistry (Weinheim an der Bergstrasse, Germany)》2006,12(27):7178-7189
A broad range of differently substituted dihydropyrimidines and thiazines can be efficiently prepared by using a four-component reaction between phosphonates, nitriles, aldehydes, and iso(thio)cyanates. The scope and limitations of this multicomponent reaction are fully described. Variation of all four components has been investigated. The nitrile and aldehyde inputs can be varied extensively, but variation of the phosphonate input remains limited. An interesting rearrangement leading to phosphoramidates has been observed. Furthermore, the multicomponent reaction seems to be restricted to the use of isocyanates with strongly electron-withdrawing substituents, but an interesting additional exchange reaction under microwave conditions leads to dihydropyrimidines with less electron-withdrawing substituents at N3. In addition, a diastereoselective formation of dihydropyrimidines has been observed when using a chiral aldehyde as the input. Finally, by changing the isocyanate component to an isothiocyanate, thiazines are efficiently formed instead of the corresponding thio-dihydropyrimidines. 相似文献
130.
Arce VB Della Védova CO Downs AJ Parsons S Romano RM 《The Journal of organic chemistry》2006,71(9):3423-3428
The conformational properties of gaseous trichloromethyl chloroformate (or "diphosgene"), ClC(O)OCCl3, have been studied by vibrational spectroscopy [IR (gas), IR (matrix), and Raman (liquid)] and quantum chemical calculations (MP2 and B3LYP with 6-311G basis sets); in addition, the structure of a single crystal at low temperature has been determined by X-ray diffraction. ClC(O)OCCl3 exhibits only one conformational form having Cs symmetry with a synperiplanar orientation of the C-O single bond relative to the C=O double bond. The calculated energy difference between the syn and anti forms, 5.73 kcal mol(-1) (B3LYP) or 7.06 kcal mol(-1) (MP2), is consistent with the experimental findings for the gas and liquid phases. The crystalline solid at 150 K [monoclinic, P2(1)/n, a = 5.5578(5) angstroms, b = 14.2895(12) angstroms, c = 8.6246(7) angstroms, beta = 102.443(2) degrees, Z = 4] likewise consists only of molecules in the syn form. 相似文献