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991.
In this work we present a hybrid particle-grid Monte Carlo method for the Boltzmann equation, which is characterized by a significant reduction of the stochastic noise in the kinetic regime. 相似文献
992.
Orietta Monticelli Dario Cavallo Sergio Bocchini Alberto Frache Fabio Carniato Alessandro Tonelotto 《Journal of polymer science. Part A, Polymer chemistry》2011,49(22):4794-4799
The efficacy of a metal‐silsesquioxane, namely, heptaisobutyl (isopropoxyde)titanium‐polyhedral oligomeric silsesquioxanes (Ti‐POSS), as initiator of the ring‐opening polymerization of L ‐lactide (LLA) has been assessed. Indeed, as demonstrated by proton nuclear magnetic resonance (1H NMR) spectroscopy and gel permeation chromatography (GPC) measurements, a well‐controlled polymerization occurs via a coordination‐insertion mechanism. Moreover, the above reaction leads to the direct insertion of the silsesquioxane molecule into the polymer backbone, thus producing a hybrid system. Differential scanning calorimetry measurements demonstrated that in comparison with a commercial poly‐L ‐lactide (PLLA), the polymers prepared with Ti‐POSS exhibit a higher crystallinity. Indeed, the presence of silsesquioxane molecules, attached to one end of the polymer chains, has been found to appreciably affect the crystal nucleation density. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011 相似文献
993.
Federico Moretti Anna Vedda Norberto Chiodini Mauro Fasoli Alessandro Lauria Vitezslav Jary Romana Kucerkova Eva Mihokova Angeloclaudio Nale Martin Nikl 《Journal of luminescence》2012,132(2):461-466
Structural and optical properties of sol–gel silica based glassceramics doped with 0.1 mol% Ce and codoped with Gd at high concentrations, from 5 mol% up to 40 mol%, are investigated and compared to those of analogous samples doped only with Ce. Raman scattering, transmission electron microscopy, and x-ray diffraction reveal the formation of Gd apatite-like silicate (Gd4.67O(SiO4)3) and of Gd pyrosilicate (Gd2Si2O7) nanophases whose morphology and crystallinity depend on the Gd concentration and thermal treatments. Optical absorption measurements demonstrate the role of the densification atmosphere in modifying the charge state of Ce ions. The incorporation of Ce3+ ions in the nanophases is put in evidence by photo- and radio-luminescence results. 相似文献
994.
Grazia Iannucci Vincenzo Passarelli Alessandro Passera Anna Iuliano 《Tetrahedron: Asymmetry》2017,28(11):1618-1625
Chiral binaphthyl diamidophosphites derived from deoxycholic acid were synthesized and used as ligands for the preparation of mononuclear Pd(II) complexes, which were employed as catalysts in the asymmetric Suzuki-Miyaura cross-coupling of arylboronic acids with aryl bromides. Among the different reaction parameters, the substrate concentration emerged as being crucial for the outcome of the reaction: the reaction was faster in a concentrated reaction mixture, and could be performed at 0 °C, where the reaction promoted by the Pd-complexes was more enantioselective affording cross-coupling products with ee up to 70%. 相似文献
995.
We discussed in a previous paper elliptic systems of partial differential equations on star-shaped domains and introduced the notions of conjugate radius and bifurcation radius. We proved that every bifurcation radius is a conjugate radius, and believed to have shown by an example that on the other hand not every conjugate radius is a bifurcation radius. This note reveals that our previous example was wrong, but it also introduces an improved example that shows the assertion that we claimed before. 相似文献
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Mattia Silvi Polyssena Renzi Deborah Rosato Cristiana Margarita Alessio Vecchioni Ivan Bordacchini Diego Morra Alessandro Nicolosi Riccardo Cari Dr. Fabio Sciubba Dr. Daniele M. Scarpino Schietroma Dr. Marco Bella 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(30):9973-9978
A challenging asymmetric reaction (aza‐Michael addition of imides to enones) has been optimized through an integrated approach involving the synthesis of a family of organocatalysts, multiple catalysis (usage of additives), and finally with rational exploration of the chemical space by the application of the experiment design. 相似文献
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