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

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

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

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 $\pi$ 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

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

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

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

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

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

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

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

A synchrotron X-ray scattering study of the crystallization behavior of mixtures of confectionary triacylglycerides: effect of chemical composition and shear on polymorphism and kinetics

Cocoa butter equivalents (CBE) are mixtures of triglycerides from multiple sources (e.g., sunflower oil, mango kernel and sal), which resemble cocoa butter (CB) in both physical and chemical properties. Despite being widely used to replace CB in chocolate products, the crystallization behavior of many CBEs is still poorly understood. The aim of this work was to develop a fundamental understanding, at the molecular level, of the crystallization behavior of selected CBEs, and compare it with that of CB. Chromatography was used to determine the composition of CBEs, in terms of fatty acids and triacylglycerides (TAGs), while their thermodynamic behavior and crystallization kinetics were studied using polarized microscopy, differential calorimetry and three different synchrotron X-ray scattering setups. CBEs of different origin and chemical composition (e.g., different ratios of the main CB TAGs, namely POP, SOS and POS) crystallized in different polymorphs and with different kinetics of nucleation, growth and polymorphic transformation. SOS rich CBEs presented showed more polymorphs than CB and POP rich samples; whereas, CBEs with high concentration of POP showed slow kinetic of polymorphic transformation towards the stable β(3L) form. Additionally, it was observed that the presence of small amounts (<1% w/w) of specific TAGs, such as OOO, PPP or SSS, could significantly affect the crystallization behavior of CBEs and CBs in terms of kinetics of polymorphic transformation and number of phases detected (multiple high melting β(2L) polymorphs were identified in all samples studied). Finally, it was found that, regardless of the CBE composition, the presence of shear could promote the formation of stable β polymorphs over metastable β’ and γ forms, and reduced the size of the crystal agglomerates formed due to increased secondary nucleation

Catalytic cracking of Lactide and Poly(Lactid Acid) to Acrylic Acid at Low Temperatures

Metals in Catalysis, Biomimetics & Inorganic Material