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991.
M. Tariq P.A.S. Forte M.F. Costa Gomes J.N. Canongia Lopes L.P.N. Rebelo 《The Journal of chemical thermodynamics》2009,41(6):790-798
A systematic study of densities and refractive indices of 17 room temperature ionic liquids is presented at four different temperatures ranging from 293 K to 333 K. The ionic liquids are grouped into four families: 1-alkyl-3-methylimidazolium bis(trifluoromethylsulfonyl)amide, [Cnmim][Ntf2], ionic liquids (with n = 2, 4, 6, 8, 10, 12, and 14); 1-alkyl-3-methylimidazolium hexafluorophosphate, [Cnmim][PF6], ionic liquids (with n = 4, 6, 8); ionic liquids based on the trihexyl(tetradecyl)phosphonium cation, [P6 6 6 14], combined with the anions bis(trifluoromethylsulfonyl)amide, [Ntf2], acetate, [OAc], and triflate, [OTf]; and [C4mim]-based ionic liquids combined with the anions [OAc], [OTf], methylsulfate [MeSO4], and tetrafluoroborate [BF4]. The data obtained were analysed to determine the effect of (i) temperature, (ii) the alkyl chain length of the 1-alkyl-3-methylimidazolium cation, and (iii) the nature of the anion. Different empirical models for the calculation of the densities of the ionic liquids were tested. Molar refractions were also calculated from the volumetric and refractive index data and the values were discussed with the aim of checking their utility in obtaining insights on the intermolecular forces and behaviour in solution of the different ionic liquids. 相似文献
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993.
I.T. Gomes B.G. Almeida A.M.L. Lopes J.P. Araújo J. Barbosa J.A. Mendes 《Journal of magnetism and magnetic materials》2010,322(9-12):1174-1177
La2/3Sr1/3MnO3?δ thin films were deposited by laser ablation on MgO substrates under low oxygen pressure cool down. Their structural and magnetic properties are presented. The magnetic and electrical resistivity measurements indicate a reduction of the Curie and the metal–insulator transition temperatures due to the formation of magnetic inhomogeneneous films, where clusters of a metallic phase are mixed in a magnetically disordered insulating matrix. By a low-angle X-ray reflectivity study we show that the thin films are chemically inhomogeneous with an oxygen deficiency in bulk of the film when compared with the film/air interfacial region. 相似文献
994.
Adrián?M.?T.?Silva Bruno?F.?Machado Helder?T.?Gomes José?L.?Figueiredo Goran?Dra?i? Joaquim?L.?Faria 《Journal of nanoparticle research》2010,12(1):121-133
Ce–Ti–O supports with different Ce/Ti molar ratios were synthesized by the solvothermal method using hexadecyltrimethylammonium
bromide. Pt nanoparticles were then supported by photochemical deposition. The shape, size, and structure of these materials
were analyzed by high-resolution transmission electron microscopy. The single CeO2 support was also prepared, consisting of agglomerated cubic particles ranging from ~3 to 8 nm. When titania was combined
with ceria, a nanostructured architecture was produced, evidencing the strong influence of Ti in the support structure. Photodeposition
of Pt nanoparticles is more efficient on Ce–Ti–O supports than in pristine CeO2. Crystalline Pt nanoparticles (mainly of ~2 to 4 nm) were detected. The catalytic properties of the materials were tested
in the selective hydrogenation of cinnamaldehyde to cinnamyl alcohol. It was observed that Pt supported on Ce–Ti–O is more
active and selective than Pt on CeO2 or TiO2 separately. The catalyst with 40 mol% Ce leads to total conversion of cinnamaldehyde in a few minutes; however, higher selectivity
toward the desired product (cinnamyl alcohol) was obtained with higher amounts of Ce (50 mol%). 相似文献
995.
Carlos Gomes da Silva João Clímaco Adiel Almeida Filho 《4OR: A Quarterly Journal of Operations Research》2010,8(2):195-211
The small world phenomenon, Milgram (1967) has inspired the study of real networks such as cellular networks, telephone call
networks, citation networks, power and neural networks, etc. The present work is about the study of the graphs produced by
efficient solutions of the bi-objective {0,1}-knapsack problem. The experiments show that these graphs exhibit properties
of small world networks. The importance of the supported and non-supported solutions in the entire efficient graph is investigated.
The present research could be useful for developing more effective search strategies in both exact and approximate solution
methods of {0,1} multi-objective combinatorial optimization problems. 相似文献
996.
T. Dekola D. Isakov E. de Matos Gomes V. H. Nunes Rodrigues M. M.R. Costa 《The European Physical Journal B - Condensed Matter and Complex Systems》2009,68(4):519-522
Glycine glycinium perrhenate is a new hydrogen bonded crystalline material that exhibits several phase transitions at low
and high temperature. At room temperature the structure shows some special features. One dimensional polar chains, linked
by strong hydrogen bonds exist parallel to [100], [010] and [–110]. The structural, thermal and dielectric properties of this
new perrhenic salt are presented and a relationship is established. 相似文献
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In this study, we consider the long-term convergence (trend toward an equilibrium) of finite state mean-field games using Γ-convergence. Our techniques are based on the observation that an important class of mean-field games can be viewed as the Euler–Lagrange equation of a suitable functional. Therefore, using a scaling argument, one can convert a long-term convergence problem into a Γ-convergence problem. Our results generalize previous results related to long-term convergence for finite state problems. 相似文献