Hybrid and multi‐point formulations of the lowest‐order mixed methods for Darcy's flow on triangles

Mixed finite element (MFE) and multipoint flux approximation (MPFA) methods have similar properties and are well suited for the resolution of Darcy's flow on anisotropic and heterogeneous domains. In this work, the link between hybrid and MPFA formulations is shown algebraically for the lowest order mixed methods of Raviart–Thomas (RT0) and Brezzi–Douglas–Marini (BDM1) on triangles. The efficiency of the four mixed formulations (Hybrid_RT0, MPFA_RT0, Hybrid_BDM1 and MPFA_BDM1) is investigated on high anisotropic and heterogeneous media and for unstructured triangular discretizations. Numerical experiments show that the MPFA_BDM1 formulation outperforms both Hybrid_RT0 and Hybrid_BDM1 in the case of anisotropic domains and highly unstructured meshes. Copyright © 2008 John Wiley & Sons, Ltd.     

Nouveaux Élastomères de polyuréthanes dérivés d'aminoacides

Synthesis and characterization of new polyurethane elastomers with rigid blocks derived from aminoacids have been achieved by polycondensation using poly(tetramethylene oxide) (PTMO) as a soft segment. Aminotelechelic oligopeptides or pseudopeptides were used in the hard block, eventually in association with lysine diisocyanate (ethyl 2, 6-diisocyanatohexanoate, LDI). Physicochemical characteristics of the so obtained materials, especially good filmmaking properties, allow their use as biomaterials of reduced toxicity.     

Chemical Composition,Antioxidant and Anti-Inflammatory Activities of Clary Sage and Coriander Essential Oils Produced on Polluted and Amended Soils-Phytomanagement Approach

The potential of essential oils (EO), distilled from two aromatic plants—clary sage (Salvia sclarea L.) and coriander (Coriandrum sativum L.)—in view of applications as natural therapeutic agents was evaluated in vitro. These two were cultivated on a trace element (TE)-polluted soil, as part of a phytomanagement approach, with the addition of a mycorrhizal inoculant, evaluated for its contribution regarding plant establishment, growth, and biomass production. The evaluation of EO as an antioxidant and anti-inflammatory, with considerations regarding the potential influence of the TE-pollution and of the mycorrhizal inoculation on the EO chemical compositions, were the key focuses. Besides, to overcome EO bioavailability and target accession issues, the encapsulation of EO in β-cyclodextrin (β-CD) was also assessed. Firstly, clary sage EO was characterized by high proportions of linalyl acetate (51–63%) and linalool (10–17%), coriander seeds EO by a high proportion of linalool (75–83%) and lesser relative amounts of γ-terpinene (6–9%) and α-pinene (3–5%) and coriander aerial parts EO by 2-decenal (38–51%) and linalool (22–39%). EO chemical compositions were unaffected by both soil pollution and mycorrhizal inoculation. Of the three tested EO, the one from aerial parts of coriander displayed the most significant biological effects, especially regarding anti-inflammatory potential. Furthermore, all tested EO exerted promising antioxidant effects (IC₅₀ values ranging from 9 to 38 g L⁻¹). However, EO encapsulation in β-CD did not show a significant improvement of EO biological properties in these experimental conditions. These findings suggest that marginal lands polluted by TE could be used for the production of EO displaying faithful chemical compositions and valuable biological activities, with a non-food perspective.     

Measurements of the total cross section differenceΔσ Т innp transmission between 0.86 and 0.94 GeV

We present results of the total cross section differenceΔσ _Т obtained in transmission measurements at the energies 0.86, 0.88, 0.91 and 0.94 GeV. The SATURNE II polarized beam of free neutrons obtained from the break-up of polarized deuterons was transmitted through the polarized Saclay frozen-spin proton target. The beam and target polarizations were oriented in the vertical direction. The present results agree with previous SATURNE measurements and improve the amplitude analysis in the forward direction.     

Angular dependence of pp spin correlation and rescattering observables between 1.80 and 2.10 GeV

A polarized proton beam extracted from SATURNE II and the Saclay polarized proton target were used to determine the spin correlation parameter Aoosk and the rescattering observablesK _os″ so; D_os″ok, N_os″sn, andN _onsk at 1.80 and 2.10 GeV. The beam polarization was oriented perpendicular to the beam direction in the horizontal scattering plane and the target polarization was directed either along the vertical axis or longitudinally. Left-right and up-down asymmetries in the second scattering were measured. A check for the beam optimization with the beam and target polarizations oriented vertically provided other observables, of which results forD _onon andK _onno at 1.80, 1.85, 2.04, and 2.10 GeV are listed here. The new data at 2.10 GeV suggest a smooth energy dependence of spin triplet scattering amplitudes at fixed angles in the vicinity of this energy.     

On the uniqueness of the equilibrium state for plane rotators

We study the classical statistical mechanics of the plane rotator, and show that there is a unique translation invariant equilibrium state in zero external field, if there is no spontaneous magnetization. Moreover, this state is then extremal in the equilibrium states. In particular there is a unique phase for the two dimensional rotator, and a unique phase for the three dimensional rotator above the critical temperature. It is also shown that in a sufficiently large external field the Lee-Yang theorem implies uniqueness of the equilibrium state.     

Photochemical substitution reactions of some alkylcobaloximes by hydroperoxides and the crystal structure of cumyl peroxide (pyridine) cobaloxime

Alkyl(pyridine) cobaloximes irradiated with visible light in the presence of tert-butyl or cumyl hydroperoxide give rise to tert-butyl or cumyl peroxide(pyridine)cobaloxime by photochemical substitution reaction. We report the structure of the cumyl peroxide(pyridine)cobaloxime determined by X-ray diffraction     

Sol-gel route to zirconia-Pt-nanoelectrode arrays 8 nm in radius: their geometrical impact in mass transport

The fabrication of advanced nanoelectrode arrays and their electrochemical characterization are presented. These nanoelectrode arrays are constituted of nanoperforations of 8 nm in radius leading to platinum and protected by an inorganic matrix made of crystalline zirconia. These nanoelectrodes arrays provide a ceramic support with a high thermal and chemical stability. These devices present a well characterized structure with a control of size, shape, and spacing of the nanoelectrodes, allowing studying in depth both the mass transport and the charge transfer properties in the nanometer range. The radial diffusion occurs when the experimental scan rate is superior to a theoretical scan rate estimated from the model proposed by Amatore and colleagues. The coupling between electrochemical analysis and nanoscale structural characterizations successfully demonstrates that the theory defined for microelectrode arrays can be directly transposed for well-defined metal-ceramic nanocomposite nanoelectrodes.