1,995 research outputs found

    Asymptotic description of solutions of the exterior Navier Stokes problem in a half space

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    We consider the problem of a body moving within an incompressible fluid at constant speed parallel to a wall, in an otherwise unbounded domain. This situation is modeled by the incompressible Navier-Stokes equations in an exterior domain in a half space, with appropriate boundary conditions on the wall, the body, and at infinity. We focus on the case where the size of the body is small. We prove in a very general setup that the solution of this problem is unique and we compute a sharp decay rate of the solution far from the moving body and the wall

    Syntheses, Structures, and Photophysical Properties of Mono- and Dinuclear Sulfur-Rich Gold(I) Complexes

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    Sulfur-rich 1,2 dithiolene and neutral thione ligands were used for the synthesis of gold complexes, some of them exhibiting aurophilic interactions. Surprisingly, the closest Au···Au contact is observed in an unsupported dinuclear complex, which makes part of a supramolecular network. Photophysical studies, combined with DFT calculations, indicate that the participations of the Au···Au interactions have some relevance to the rich luminescence properties of these compounds

    Integral potential method for a transmission problem with Lipschitz interface in R^3 for the Stokes and Darcy–Forchheimer–Brinkman PDE systems

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    The purpose of this paper is to obtain existence and uniqueness results in weighted Sobolev spaces for transmission problems for the non-linear Darcy-Forchheimer-Brinkman system and the linear Stokes system in two complementary Lipschitz domains in R3, one of them is a bounded Lipschitz domain with connected boundary, and the other one is the exterior Lipschitz domain R3 n. We exploit a layer potential method for the Stokes and Brinkman systems combined with a fixed point theorem in order to show the desired existence and uniqueness results, whenever the given data are suitably small in some weighted Sobolev spaces and boundary Sobolev spaces

    Antioxydant activity, oxidative stability properties of Colza oil, comparison of mechanical agitated and ultrasonic extraction on green tea catechins of Camellia sinensis L.

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    peer reviewedUltrasonic extraction “UE” used to optimize the extraction yield of phenolic compounds “PC” from green tea Camellia sinensis L., and compared with mechanical agitated extraction “MAE”. UE was applied at different times (15, 10 and 5min) and temperatures (25, 60 and 95°C) and MAE was performed at these experimental conditions (15 min, 95°C, 400 rpm). Results demonstrate that the maximum yield of epigallocatechin 3-gallate “EGCG” extracted by UE was significantly (P < 0.05) higher than that obteined using MAE (136 mg/g vs 100 mg/g, respectively). The optimum conditions for the polyphenol compounds “PC” recovery are obtained using UE during 15 min at 95°C (~134.66 mg/g). Four catechins from extracted PC were identified using high-performance liquid chromatography equipped with a diode array detector and liquid chromatography mass spectrometry “HPLC-DAD & LC-MS”: epigallocatechin “EGC”, epicatechin “EC”, epigallocatechingallate “EGCG”, and epicatechin-gallate “ECG”. EGCG is the major compound in polyphenol extracts representing 60 %. The antioxidant capacity of the obtained extracts was also studied. Diphényl-2-pycril-hydrazyl “DPPH” scavenging activity is higher for UE than MAE (~ 90 % vs ~85%). Moreover, the PC obtained by UE added to colza oil had a higher oxidative stability, determined by rancimat than those extracted by MAE method (~30.62 h vs ~21.26 h). Results indicate the suitability of UE method for production of PC as potent antioxidant for stabilization of vegetable oils such as colza oil

    Measurement of J/ψ production in association with a W ± boson with pp data at 8 TeV

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    A measurement of the production of a prompt J/ψ meson in association with a W± boson with W± → μν and J/ψ → μ+μ− is presented for J/ψ transverse momenta in the range 8.5–150 GeV and rapidity |yJ/ψ| &lt; 2.1 using ATLAS data recorded in 2012 at the LHC. The data were taken at a proton-proton centre-of-mass energy of s = 8 TeV and correspond to an integrated luminosity of 20.3 fb−1. The ratio of the prompt J/ψ plus W± cross-section to the inclusive W± cross-section is presented as a differential measurement as a function of J/ψ transverse momenta and compared with theoretical predictions using different double-parton-scattering cross-sections. [Figure not available: see fulltext.]
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