Influence de la pression partielle d'oxygene sur la nature des defauts ponctuels dans Ca2LaFe3O8+x

The type of point defects in non-stoichiometric Ca₂LaFe₃O_8+x ferrite has been studied by measuring the variation of electrical conductivity with oxygen partial pressure at various temperatures. Several ordering possibilities occur. The oxygen atoms inserted, mostly 1-charged, have a strong tendency to couple at sufficient oxygen pressure and at low temperature. Interstitial oxygen atoms in the lattice vacancies induce structural evolution as non-stoichiometry becomes significant enough.     

Modeling long term memory effects in microwave power amplifiers for system level simulations

Accurate and dynamic behavioral models of SSPAS become of prime importance in system level analysis and design of modern communication and detection systems. This paper describes a new method to characterize and reproduce nonlinear memory effects in behavioral models ofSspas. We highlight, in a first section, the detailed mathematical development, whose the starting point is the Volterra series expansion, and ends to the nonlinear impulse response notion. The new model extraction relies on envelope transient simulations or time-domain measurements of complex envelopes at externDut reference accesses. This modeling technique is simple and enables a good prediction of nonlinear memory effects and especially long term memory effects and nonlinear transient behaviors. Simulations and measurements based extractions of this model are presented through significant amplifier examples.     

Scoring binding affinity of multiple ligands using implicit solvent and a single molecular dynamics trajectory: application to influenza neuraminidase

We explore a perturbative approach to calculation of binding free energy of multiple ligands, based on a single molecular dynamics simulation of a reference ligand-receptor complex and analysis via a hybrid force field/continuum model potential. The methodology is applied to prediction of relative binding free energies of 10 Influenza neuraminidase inhibitors, using Poisson-Boltzmann and generalised Born models of implicit solvent. These single-step MM-PB/SA and MM-GB/SA approaches predict the experimentally most potent ligand as first- or second-ranked according to total binding free energy. Ranking of inhibitors displays only moderate sensitivity to the choice of reference trajectory and ligand partial charge scheme. When ranked according to total electrostatic binding free energy, correlation with experiment improves (r(2) of 0.72); this may be related to underestimated first solvation shell effects by the implicit water models. Therefore, to increase the generality of this single-step approach as part of a potential computational compound optimisation strategy, further development of the treatment of short-range solvent interactions is warranted.     

Etude des microcircuits hyperfréquences en régime dynamique

A critical study of the transmissionlinematrix method has been carried out by the authors to apply it for a dynamical study of the microwaves microcircuits. As a consequence of this critical study the authors suggest important improvements on the following three points: the dynamical process initialization, the rapidity and precision of computer calculation, the treatment of the resulting time signal. The method being a dynamical one, a first selecting filtering of the information to be transmitted is performed by using the geometrical and electrical symetries. A fast Fourier transform and a simplification of the computation procedure give a gain in time and precision. At last a better reading of the frequency response spectra is obtained by treating with various windows of convolution the resulting time signal.     

Sur l'utilisation des modifications de barrière de surface avec la température pour caractériser les états de surface

This paper deals with the determination of the density and the energy level of semiconductor surface states from the variations in the surface barrier height with temperature in the range 100–400 K. Examples of calculations for discrete energy level states are given.     

cis-4,7,10,trans-13–22∶4 fatty acid distribution in phospholipids of pectinid species Aequipecten opercularis and Pecten maximus

The distribution of cis-4,7,10,trans-13-docosate-traenoic (c4,7,10,t13–22∶4), a peculiar FA previously isolated in the glycerophospholipids of some pectinid bivalves, was investigated in glycerophospholipid classes and subclasses of separated organs (gills, mantle, gonads, and muscle) of the queen scallop Aequipecten opercularis and the king scallop Pecten maximus. Plasmalogen (Pls) and diacyl + alkyl (Ptd) forms of serine, ethanolamine, and choline glycerophospholipids were isolated by HPLC and their FA compositions analyzed by GC-FID. Pls and Ptd forms of serine glycerophospholipids (PlsSer and PtdSer), and to a lesser extend the Pls form of ethanolamine glycerophospholipids (PlsEtn), were found to be specifically enriched with c4,7,10,t13–22∶4. This specificity was found to decrease in the tested organs in the following order: gills, mantle, gonad, and muscle. In gills, c4,7,10,t13–22∶4 was shown to be the main unsaturated FA of serine glycerophospholipids in both Pls and Ptd forms (23.8 and 19.4 mol%, respectively, for A. opercularis, and 21.0 and 26.2 mol% for P. maximus). These results represent the first comprehensive report on the FA composition of plasmalogen serine subclass isolated from pectinid bivalves. The specific association of the PlsSer with the c4,7,10,t13–22∶4 for the two pectinid species can be paralleled to the specific association of the PlsSer with the non-methylene interrupted (NMI) FA and 20∶1(n−11) observed in mussels, clams, and oysters (Kraffe, E., Soudant, P., and Marty, Y. (2004) Fatty Acids of Serine, Ethanolamine and Choline Plasmalogens in Some Marine Bivalves, Lipids 39, 59–66.) This, led us to hypothesize a similar functional significance for c4,7,10,t13–22∶4, NMI FA, and 20∶1(n−11) associated with PlsSer subclass of bivalves.     

In vitro and in vivo efficacy of sulfo‐carrabiose,a sugar‐based cosmetic ingredient with anti‐cellulite properties

Most of adult women exhibit cellulite on the hips, buttock and thighs. Although extracellular matrix and lymphatic system disorders can increase its appearance, cellulite basically results from an excessive fat storage in the adipose tissue which exerts considerable pressure on the surrounding skin tissue and creates a dimpled irregular appearance. Caffeine, the most widely used anti‐cellulite ingredient, favours fat break‐down by inhibiting the phosphodiesterase enzyme and encouraging a high intracellular level of cAMP. A series of studies has shown that spermine and spermidine, two ubiquitous polyamines, encouraged fat storage and slowed fat break‐down in the adipose tissue. Besides, it was shown that heparan sulfate glycosaminoglycans had a strong affinity for polyamines. To design a new cosmetic ingredient with anti‐cellulite properties, we used molecular modelling to screen several ingredients with a structure similar to that of heparan sulfate glycosaminoglycans. This way, we identified sulfo‐carrabiose as a potent molecule for trapping spermine and spermidine. These virtual results were first confirmed in tubo where sulfo‐carrabiose was shown to dose‐dependently inactivate spermine and spermidine. In vitro, adipocytes cultured with sulfo‐carrabiose exhibited a significant reduction of lipogenesis and a significant increase of lipolysis. When sulfo‐carrabiose was incorporated in a cosmetic formula, significant improvements were observed in thigh circumference, with better results than those obtained with caffeine after 28 days of use. Furthermore, a combination of caffeine and sulfo‐carrabiose led to results significantly better than those obtained with caffeine alone. As measured by fringe projection, thigh volume was also significantly reduced after sulfo‐carrabiose treatment. Finally, the appearance of cellulite assessed by clinical evaluation was also significantly reduced within 28 days.