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71.
Rached Salhi Ramzi Maalej Yannick Guyot Laetitia Rapenne Jean-Luc Deschanvres 《Journal of luminescence》2011,131(11):2311-2316
Erbium-doped Y2O3 films were prepared by aerosol-UV assisted metal-organic chemical vapour deposition (MOCVD) at 410 °C. The effects of humidity of carrier gas and UV-assistance on their structure and optical properties were investigated on the as-deposited and thermal annealed films using infrared spectroscopy, X-ray diffraction and transmission electron microscopy. It was found that the as-deposited Er:Y2O3 films crystallise in the Y2O3 cubic structure and present a very low organic contamination when the deposition takes place under high air humidity and, even better, with UV-assistance. After annealing, two different structural phases are observed corresponding to the cubic and the monoclinic structures of Y2O3. The Er3+ luminescence analysed in the visible and IR regions, shows the classical green transitions. The best optical properties were obtained with as-deposited and annealed Er:Y2O3 films grown under high air humidity with UV-assistance. Under such deposition conditions, 4I13/2 lifetimes was found to be 3.07 and 6.1 ms for films annealed at 800 and 1000 °C, respectively, and up-conversion phenomena were underlined. This indicates that the deposition conditions, in particular air humidity, play an important role in the luminescent properties even after annealing. 相似文献
72.
Estruch T Jaeck J Pardo F Derelle S Primot J Pelouard JL Haidar R 《Optics letters》2011,36(16):3160-3162
We investigate the strong electromagnetic coupling that settles in dual metallic grating structures. This coupling is evidenced to lead to a perfect optical extinction in the transmission spectrum. The behavior of this perfect extinction that strongly depends on the longitudinal space and the lateral displacement between the two gratings can be explained by a simple model that describes the interference between a propagating mode and a couple of evanescent modes. The results show that the electromagnetic transmission of the structure can be tuned by controlling the position of this perfect transmission extinction and thus pave the way to new types of infrared tunable filters. 相似文献
73.
Jean-Luc Marichal Pierre Mathonet 《Journal of Mathematical Analysis and Applications》2011,380(1):105-116
By considering a least squares approximation of a given square integrable function f:n[0,1]→R by a multilinear polynomial of a specified degree, we define an index which measures the overall interaction among variables of f. This definition extends the concept of Banzhaf interaction index introduced in cooperative game theory. Our approach is partly inspired from multilinear regression analysis, where interactions among the independent variables are taken into consideration. We show that this interaction index has appealing properties which naturally generalize several properties of the Banzhaf interaction index. In particular, we interpret this index as an expected value of the difference quotients of f or, under certain natural conditions on f, as an expected value of the derivatives of f. Finally, we discuss a few applications of the interaction index in aggregation function theory. 相似文献
74.
Hitomi Anzai Makoto Ohta Jean-Luc Falcone Bastien Chopard 《Journal of computational science》2012,3(1-2):1-7
A modern technique to treat cerebral aneurysms is to insert a flow diverter in the parent artery. In order to produce an optimal design of such devices, we consider a methodology combining simulated annealing optimization and lattice Boltzmann simulations. Our results surpass, in terms of stent efficiency, those obtained in the recent literature with an other optimization method. Although our approach is still in 2D, it demonstrates the potential of the method. We give some hint on how the 3D cases can be investigated. 相似文献
75.
Coropceanu V Kwon O Wex B Kaafarani BR Gruhn NE Durivage JC Neckers DC Brédas JL 《Chemistry (Weinheim an der Bergstrasse, Germany)》2006,12(7):2073-2080
The nature of vibronic coupling in fused polycyclic benzene-thiophene structures has been studied using an approach that combines high-resolution gas-phase photoelectron spectroscopy measurements with first-principles quantum-mechanical calculations. The results indicate that in general the electron-vibrational coupling is stronger than the hole-vibrational coupling. In acenedithiophenes, the main contributions to the hole-vibrational coupling arise from medium- and high-frequency vibrations. In thienobisbenzothiophenes, however, the interaction of holes with low-frequency vibrations becomes significant and is larger than the corresponding electron-vibrational interaction. This finding is in striking contrast with the characteristic pattern in oligoacenes and acenedithiophenes in which the low-frequency vibrations contribute substantially only to the electron-vibrational coupling. The impact of isomerism has been studied as well. 相似文献
76.
The parameters that influence the conformation of poly(propylene imine) dendrimers were investigated by molecular simulations using molecular mechanics and simulated annealing methods. Dendrimers with two types of peripheral units able to communicate via hydrogen bonding-amine and amide moieties-were considered in order to study the role that secondary interactions among the end groups have in the spatial organization of the dendritic branches. Radial atomic density profiles and radial atomic probability distributions were used to extract global properties, such as the degree of packing of the branches, the distribution of the monomers throughout the molecular volume, and the extent and characteristics of the surface region. Information was also obtained about the nature, location, and extent of formation of the hydrogen bonds, as well as their evolution with dendrimer generation and their assembly into networks. The analyses were supported by a detailed investigation of the first two generations, with an emphasis on the relationship between hydrogen bonding and the compactness and stability of the molecules; this allowed us to account for the generational evolution of hydrogen bonding that is experimentally observed in several poly(propylene imine) dendrimers. 相似文献
77.
Caillau Jean-Baptiste Djema Walid Gouzé Jean-Luc Maslovskaya Sofya Pomet Jean-Baptiste 《Journal of Optimization Theory and Applications》2022,194(2):375-407
Journal of Optimization Theory and Applications - We consider the problem of maximization of metabolite production in bacterial cells formulated as a dynamical optimal control problem (DOCP).... 相似文献
78.
Sylvain Rodriguez Jean-Luc Wolfender Kurt Hostettmann Gendaramyn Odontuya Ondognii Purev 《Helvetica chimica acta》1996,79(2):363-370
Chemical screening of the secondary metabolites from Halenia corniculata L. (CORNAZ ), by LC/UV,LC/TSP-MS (thermospray), and LC/ES-MS (electrospray) was used for the targeted isolation of corniculoside ( 1 ), a new biosidic ester secoiridoid. The structure was established as 7-β-[(E)-4′-O-(β-D -glucopyranosyl)caffeoyloxy]-sweroside by 1D- and 2D-NMR, LC/UV, LC/MS, and FAB-MS data, in combination with chemical reactions. 相似文献
79.
The synthesis of 2-substituted 1,4-diacetoxybutadiene derivatives with a partial control of stereochemistry is described from two potentially precursor enals by a judicious choice of experimental conditions (Ac2O/DMAP in Et3N). These conditions have been successfully applied in the first total synthesis of caulerpenyne. 相似文献
80.
Petkova V Benattar JJ Zoonens M Zito F Popot JL Polidori A Jasseron S Pucci B 《Langmuir : the ACS journal of surfaces and colloids》2007,23(8):4303-4309
The possibility of organizing detergent-solubilized membrane proteins in a plane within the core of Newton black films (NBFs) formed from fluorinated surfactants has been investigated. Fluorinated surfactants have the interesting characteristics of being poorly miscible with detergents and highly surface-active. As a result, when a membrane protein-the transmembrane domain of OmpA (tOmpA)-solubilized by the nonionic detergent C8E4 (tetraethylene glycol monooctyl ether) was injected under a monolayer of fluorinated surfactant, C8E4 and tOmpA/C8E4 complexes remained confined to the subphase. Vertical, macroscopic NBFs were drawn, and their structure was investigated by means of X-ray reflectivity. Depending on experimental conditions, the protein was shown to organize into either one or two monolayers stabilized by two monolayers of fluorinated surfactant. Two different mechanisms of protein insertion were investigated: (i) attachment of polyhistidine-tagged tOmpA/C8E4 complexes to nickel-bearing polar groups born by a fluorinated surfactant and (ii) spontaneous diffusion into the surfactant films. Possible applications are discussed. 相似文献