350 research outputs found

    Proximity effects in spin-triplet superconductor-ferromagnet heterostucture with spin-active interface

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    We study the physical properties of a ballistic heterostructure made of a ferromagnet (FM) and a spin-triplet superconductor (TSC) with a layered structure stacking along the direction perpendicular to the planes where a chiral px+ipy pairing occurs and assuming spin dependent processes at the interface. We use a self-consistent Bogoliubov-de Gennes approach on a three-dimensional lattice to obtain the spatial profiles of the pairing amplitude and the magnetization. We find that, depending on the strength of the ferromagnetic exchange field, the ground state of the system can have two distinct configurations with a parallel or anti-parallel collinearity between the magnetic moments in the bulk and at the interface. We demonstrate that a magnetic state having non coplanar interface, bulk and Cooper pairs spins may be stabilized if the bulk magnetization is assumed to be fixed along a given direction. The study of the density of states reveals that the modification of the electronic spectrum in the FM plays an important role in the setting of the optimal magnetic configuration. Finally, we find the existence of induced spin-polarized pair correlations in the FM-TSC system.Comment: 15 pages, 11 figure

    Magnetic Insulator-Induced Proximity Effects in Graphene: Spin Filtering and Exchange Splitting Gaps

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    We report on first-principles calculations of spin-dependent properties in graphene induced by its interaction with a nearby magnetic insulator (Europium oxide, EuO). The magnetic proximity effect results in spin polarization of graphene π\pi orbitals by up to 24 %, together with large exchange splitting bandgap of about 36 meV. The position of the Dirac cone is further shown to depend strongly on the graphene-EuO interlayer. These findings point towards the possible engineering of spin gating by proximity effect at relatively high temperature, which stands as a hallmark for future all-spin information processing technologies.Comment: 5 pages, 4 figure

    Arginine and citrulline do not stimulate growth of two Oenococcus oeni strains in wine

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    Arginine metabolism by wine lactic acid bacteria (LAB) may lead to wine quality degradation. While arginine is essential for growth of the wine relevant LAB Oenococcus oeni, it remains unclear whether it also stimulates its growth. This study evaluated the effect of arginine and citrulline, the partially metabolized intermediate of the arginine deiminase pathway, on the growth of two commercial O. oeni strains in comparison with a Lactobacillus buchneri strain in wine and at wine pH values. Neither arginine nor citrulline increased growth of both O. oeni strains in comparison with the L. buchneri strain. However, arginine and citrulline were partially degraded in all incubations. The extent of citrulline degradation correlated with lower pH values in oenococcal cultivations but with higher pH values in those of the L. buchneri strain. The degradation kinetics of O. oeni and L. buchneri for malic acid and arginine differed and the latter grew in sterile filtered post-malolactic fermentation wine. This study shows that arginine and citrulline did not stimulate growth of the two O. oeni strains studied, and that their physiological role differed among the wine LAB considered. While arginine may play a role in wine microbiological stability, other nutrients should be investigated for their suitability to create a selective ecological advantage for O. oeni strains in win

    Etude sur l\u27accès du jeune public aux activités culturelles gérées ou soutenues par la Ville de Paris

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    Rapport de l\u27Inspection générale concernant l\u27accès des jeunes Parisiens (exceptée la Petite enfance) aux activités culturelles gérées ou soutenues par la Ville de Paris. Le rapport aborde le sujet sous quatre angles : - l\u27offre proposée aux jeunes par les institutions culturelles liées à la Ville, - la contribution de la Ville à l\u27éducation artistique et culturelle dispensée dans le cadre de la vie scolaire et périscolaire, - le dispositif municipal d\u27aide aux activités culturelles exercées en dehors de la sphère scolaire, - les faiblesses de l\u27action de Paris et les voies possibles d\u27amélioration

    3D homogenised strength criterion for masonry: application to drystone retaining walls

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    A 3D strength criterion for masonry is constructed based on yield design theory. Yield design homogenisation provides a rigorous theoretical framework to determine the yield strength properties of a periodic medium, based on the properties of its constituent materials. First, theoretical basis of 2D homogenisation of periodic media, and more particularly its application in the framework of yield design, will be retrieved. Then, 2D principles are extended to exhibit a 3D domain of running-bond masonry. This criterion is finally used to assess the stability of a drystone retaining wall loaded by an axle load, and theoretical results are compared to experimental data. Perspectives on this work are given as a conclusion

    GDF-15 is elevated in children with mitochondrial diseases and is induced by mitochondrial dysfunction

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    Background We previously described increased levels of growth and differentiation factor 15 (GDF-15) in skeletal muscle and serum of patients with mitochondrial diseases. Here we evaluated GDF-15 as a biomarker for mitochondrial diseases affecting children and compared it to fibroblast-growth factor 21 (FGF-21). To investigate the mechanism of GDF-15 induction in these pathologies we measured its expression and secretion in response to mitochondrial dysfunction. Methods We analysed 59 serum samples from 48 children with mitochondrial disease, 19 samples from children with other neuromuscular diseases and 33 samples from aged-matched healthy children. GDF-15 and FGF-21 circulating levels were determined by ELISA. Results Our results showed that in children with mitochondrial diseases GDF-15 levels were on average increased by 11-fold (mean 4046pg/ml, 1492 SEM) relative to healthy (350, 21) and myopathic (350, 32) controls. The area under the curve for the receiver-operating-characteristic curve for GDF-15 was 0.82 indicating that it has a good discriminatory power. The overall sensitivity and specificity of GDF-15 for a cut-off value of 550pg/mL was 67.8% (54.4%-79.4%) and 92.3% (81.5%-97.9%), respectively. We found that elevated levels of GDF-15 and or FGF-21 correctly identified a larger proportion of patients than elevated lev- els of GDF-15 or FGF-21 alone. GDF-15, as well as FGF-21, mRNA expression and protein secretion, were significantly induced after treatment of myotubes with oligomycin and that levels of expression of both factors significantly correlated. Conclusions Our data indicate that GDF-15 is a valuable serum quantitative biomarker for the diagnosis of mitochondrial diseases in children and that measurement of both GDF-15 and FGF-21 improves the disease detection ability of either factor separately. Finally, we demonstrate for the first time that GDF-15 is produced by skeletal muscle cells in response to mitochon- drial dysfunction and that its levels correlate in vitro with FGF-21 level

    Application of X-ray Microcomputed Tomography for the Static and Dynamic Characterization of the Microstructure of Oleofoams

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    Oleofoams are a novel, versatile, and biocompatible soft material that finds application in drug, cosmetic or nutraceuticals delivery. However, due to their temperature-sensitive and opaque nature, the characterization of oleofoams' microstructure is challenging. Here, synchrotron X-ray microcomputed tomography and radiography are applied to study the microstructure of a triglyceride-based oleofoam. These techniques enable non-destructive, quantitative, 3D measurements of native samples to determine the thermodynamic and kinetic behavior of oleofoams at different stages of their life cycle. During processing, a constant bubble size distribution is reached after few minutes of shearing, while the number of bubbles incorporated keeps increasing until saturation of the continuous phase. Low amounts of solid triglycerides in oleofoams allow faster aeration and a more homogeneous microstructure but lower thermodynamic stability, with bubble disproportionation and shape relaxation over time. Radiography shows that heating causes Ostwald ripening and coalescence of bubbles, with an increase of their diameter and sphericity

    Combinatorial strategies to find new catalysts for asymmetric hydrogenation based on the versatile coordination chemistry of METAMORPhos ligands

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    To extend the toolbox and find improved catalysts, anionic METAMORPhos ligands and neutral amino-acid-based ligands were used separately and in mixtures to form Rh complexes used in the asymmetric hydrogenation of eight industrially relevant substrates. Spectroscopic studies showed that under the catalytic conditions, the mononuclear complex with two different ligands (the heterocombination) is the main complex in solution if both the anionic and neutral ligands have the same chirality. If the neutral ligand and the anionic ligand have the opposite chirality at the P atom, monometallic and bimetallic heterocomplexes were detected by NMR spectroscopy and MS. For the majority of substrates evaluated in this study, higher enantioselectivities were obtained if the complexes used were based on the heterocombination of an anionic and a neutral ligand compared to respective homocombinations. After we found the initial leads, higher turnover numbers and enantioselectivities could be obtained easily by further exploring focused ligand libraries. The superior activity of the complexes based on the different ligands is highlighted by their robustness: significant divergence from a 1:1 ratio between the ligands does not lower the selectivity of the catalyst, although more of the competing homocomplexes are formed under these conditions

    Evaluation of different conditions to enhance the performances of Lactobacillus pentosus OM13 during industrial production of Spanish-style table olives

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    The main objective was to set up a methodology to improve the high volume production of green table olives, cv. Nocellara del Belice. Lactobaccillus pentosus OM13 was applied during three different industrial processes of table olives as follows: trial one (IOP1) was subjected to an addition of lactic acid until a brine level of pH 7.0 was reached; trial two (IOP2) subjected to same addition of lactic acid as in trial one plus nutrient adjuvant; and trial three (IOP3) subjected to same addition of lactic acid as in trial one, but with the strain L. pentosus OM13 acclimatized in brine for 12 h before inoculation. These trials were compared against two untreated controls (spontaneously fermented and addition of L. pentosus OM13 only). Within the third day of fermentation, the pH of the brines decreased significantly, reaching pH 4.85 for trial three, pH 5.15 for trial two, and pH 5.92 for trial one. The pH of both controls decreased more slowly, and had values below pH 5.0 only after the fifteenth day of fermentation (control one) and the sixty-fifth day of fermtation (control two). Trial three reached the highest lactic acid bacteria (LAB) concentration on the third day of fermentation. After six days of fermentation, all trials showed similar values of LAB counts that were significantly higher compared to control number one. The result from genotypic identification showed that L. pentosus OM13 was the most frequently isolated in the inoculated trials. Lactobacillus plantarum, Lactobacillus coryniformis and Pediococcus pentosaceous were also detected at very low concentrations. Homoguaiacol, 2-butanol, 4-ethylphenol, phenylethyl alcohol and 4-ethylphenol were the volatile organic compounds detected at the highest levels in all experimental trials. Trial three showed a higher concentration of squalene that was not detected in other trials. The highest sensory scores of green olive aroma and overall satisfaction were found for all experimental olives, especially for those of trial one and trial two, that differed significantly from the untreated controls. This study provides evidence that the addition of lactic acid, nutrient adjuvants and, most importantly, the acclimatization of LAB cells significantly shortens the acidification process of olive brine, and improves safety and sensory quality. Shorter acidification processes result in a more rapid transformation of table olives, with reduced commodity loss and lower costs of production compared to conventional manufacturing protocols
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