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961.
Foundations of Computational Mathematics - We consider stochastic systems of interacting particles or agents, with dynamics determined by an interaction kernel, which only depends on pairwise... 相似文献
962.
Mauro V. De Almeida Mara Rubia C. Couri João Vitor De Assis Cleber P. A. Anconi Hélio F. Dos Santos Wagner B. De Almeida 《Magnetic resonance in chemistry : MRC》2012,50(9):608-614
Density functional theory (DFT) calculations of 1H NMR chemical shifts for l ‐quebrachitol isomers were performed using the B3LYP functional employing the 6‐31G(d,p) and 6‐311 + G(2d,p) basis sets. The effect of the solvent on the B3LYP‐calculated NMR spectrum was accounted for using the polarizable continuum model. Comparison is made with experimental 1H NMR spectroscopic data, which shed light on the average uncertainty present in DFT calculations of chemical shifts and showed that the best match between experimental and theoretical B3LYP 1H NMR profiles is a good strategy to assign the molecular structure present in the sample handled in the experimental measurements. Among four plausible O‐methyl‐inositol isomers, the l ‐quebrachitol 2a structure was unambiguously assigned based only on the comparative analysis of experimental and theoretical 1H NMR chemical shift data. The B3LYP infrared (IR) spectrum was also calculated for the four isomers and compared with the experimental data, with analysis of the theoretical IR profiles corroborating assignment of the 2a structure. Therefore, it is confirmed in this study that a combined experimental/DFT spectroscopic investigation is a powerful tool in structural/conformational analysis studies. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
963.
Ultrasound-assisted oxidative process for sulfur removal from petroleum product feedstock 总被引:1,自引:0,他引:1
Paola de A. Mello Fbio A. Duarte Matheus A.G. Nunes Mauricio S. Alencar Elizabeth M. Moreira Mauro Korn Valderi L. Dressler rico M.M. Flores 《Ultrasonics sonochemistry》2009,16(6):732-736
A procedure using ultrasonic irradiation is proposed for sulfur removal of a petroleum product feedstock. The procedure involves the combination of a peroxyacid and ultrasound-assisted treatment in order to comply with the required sulfur content recommended by the current regulations for fuels. The ultrasound-assisted oxidative desulfurization (UAOD) process was applied to a petroleum product feedstock using dibenzothiophene as a model sulfur compound. The influence of ultrasonic irradiation time, oxidizing reagents amount, kind of solvent for the extraction step and kind of organic acid were investigated. The use of ultrasonic irradiation allowed higher efficiency for sulfur removal in comparison to experiments performed without its application, under the same reactional conditions. Using the optimized conditions for UAOD, the sulfur removal was about 95% after 9 min of ultrasonic irradiation (20 kHz, 750 W, run at 40%), using hydrogen peroxide and acetic acid, followed by extraction with methanol. 相似文献
964.
Massimo Boiocchi Dr. Luigi Fabbrizzi Prof. Mauro Garolfi Dr. Maurizio Licchelli Prof. Lorenzo Mosca Dr. Cristina Zanini Dr. 《Chemistry (Weinheim an der Bergstrasse, Germany)》2009,15(42):11288-11297
Copper(II) azacyclam complexes 3 2+ and 4 2+ were obtained through a metal‐templated procedure involving the pertinent open‐chain tetramine, formaldehyde and a phenylurea derivative as a locking fragment. Both metal complexes can establish interactions with anions through the metal centre and the amide NH group. Equilibrium studies in DMSO by a spectrophotometric titration technique were carried out to assess the affinity of 3 2+ and 4 2+ towards anions. While the NH group of an amide model compound and the metal centre of the plain CuII(azacyclam)2+ complex do not interact at all with anions, 3 2+ and 4 2+ establish strong interactions with oxo anions, profiting from a pronounced cooperative effect. In particular, 1) they form stable 1:1 and 1:2 complexes with H2PO4? ions in a stepwise mode with both hydrogen‐bonding and metal–ligand interactions, and 2) in the presence of CH3COO?, they undergo deprotonation of the amido NH group and thus profit from axial coordination of the partially negatively charged carbonyl oxygen atom in a scorpionate binding mode. 相似文献
965.
Maria-Beatrice Coltelli Stefania Savi Mauro Aglietto Francesco Ciardelli 《Polymer Science Series A》2009,51(11-12):1249-1261
The recovery of poly(ethylene terephthalate) from post-consumer packaging products, such as beverage bottles, allowed to obtain flakes with a purity level suitable for reprocessing. Among many possibilities, the blending with polyolefins can provide toughened materials but, as poly(ethylene terephthalate) and polyolefins are immiscible, different methods of reactive compatibilization were followed to achieve a fine dispersion of polyolefln domains into a poly(ethylene terephthalate) matrix. In this meanwhile the use of a functionalized polyolefin, bearing reactive groups toward poly(ethylene terephthalate) terminals, is a promising route to obtain grafted copolymers acting as interface stabilizers. In particular, the use in the melt blending of ester or hydroxyl functionalized polyolefins in the presence of transesterification catalysts and/or anhydride functionalized polyolefins as compatibilizer precursors were both investigated by focusing onto chemical aspects. The prepared blends were analyzed through suitable fractionation methods, such as selective extractions, and spectroscopic analysis in order to identify the molecular architecture of the macromolecules resulting from the process and study their effectiveness at the interface region. Moreover the phase morphology and the thermo-mechanical properties were investigated and correlated to the structure of the macromolecular species in the system. 相似文献
966.
Luigi Campanella Tania Gatta Emanuela Gregori Mauro Tomassetti 《Monatshefte für Chemie / Chemical Monthly》2009,55(2):965-972
Abstract
Antioxidant and radical-scavenging properties are alleged to form the basis of the therapeutic properties attributed to the papaya and papaya-based food and drug integrators that have recently appeared on the market. In the present research a biosensor-based method was used to determine the antioxidant capacity of papaya fruit as is, that of several food and drug integrators, and lastly of pure papain alone. Results are compared using a reference spectrofluorimetric method and two other spectrophotometric methods. In addition pro-oxidant properties of the same samples were also checked using two colorimetric methods. 相似文献967.
Luigi Campanella Tania Gatta Emanuela Gregori Mauro Tomassetti 《Monatshefte für Chemie / Chemical Monthly》2009,140(8):965-972
Abstract Antioxidant and radical-scavenging properties are alleged to form the basis of the therapeutic properties attributed to the
papaya and papaya-based food and drug integrators that have recently appeared on the market. In the present research a biosensor-based
method was used to determine the antioxidant capacity of papaya fruit as is, that of several food and drug integrators, and
lastly of pure papain alone. Results are compared using a reference spectrofluorimetric method and two other spectrophotometric
methods. In addition pro-oxidant properties of the same samples were also checked using two colorimetric methods.
Graphical abstract 相似文献
968.
969.
970.
Alessandro Bisio Giacomo Mauro D’Ariano Paolo Perinotti 《Foundations of Physics》2017,47(8):1065-1076
Quantum cellular automata and quantum walks provide a framework for the foundations of quantum field theory, since the equations of motion of free relativistic quantum fields can be derived as the small wave-vector limit of quantum automata and walks starting from very general principles. The intrinsic discreteness of this framework is reconciled with the continuous Lorentz symmetry by reformulating the notion of inertial reference frame in terms of the constants of motion of the quantum walk dynamics. In particular, among the symmetries of the quantum walk which recovers the Weyl equation—the so called Weyl walk—one finds a non linear realisation of the Poincaré group, which recovers the usual linear representation in the small wave-vector limit. In this paper we characterise the full symmetry group of the Weyl walk which is shown to be a non linear realization of a group which is the semidirect product of the Poincaré group and the group of dilations. 相似文献