628 research outputs found

    Entre héritage et renouvellement : le cas de Viviane dans "l'Enchanteur" de René Barjavel

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    Aymon de Montfalcon et l’Observance : la fondation controversĂ©e des couvents de Savigny, de Sainte-Catherine du Jorat et de Morges

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    AttachĂ© Ă  l’Observance, tendance acquise vraisemblablement au contact de sa rĂ©gion d’origine, la Savoie, Aymon de Montfalcon va entreprendre la fondation de deux couvents dans le Pays de Vaud durant son Ă©piscopat : les carmes de Sainte-Catherine du Jorat et les franciscains observants de Morges. Il mena Ă  son terme Ă©galement un projet de fondation laissĂ© en suspens par son prĂ©dĂ©cesseur, l’établissement du Tiers-Ordre franciscain de Savigny. Bien qu’appartenant tous trois Ă  des ordres diffĂ©rents, ils ont nĂ©anmoins comme point commun d’ĂȘtre issus de la mouvance observante

    Laser-induced periodic alignment of Ag nanoparticles in soda-lime glass

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    International audienceOne-, two- or three-dimensional arrays of closely spaced silver nanoparticles may lead to new optical properties, due to short or long range coupling between their resonant surface plasmons, so that the spatially controlled growth of silver nanoparticles provides an efficient way to tune their optical properties. Towards this way, we present here the periodic pattern of a glass surface with silver nanoparticles by continuous ultraviolet laser exposure. The formation of the 160 nm period pattern is well described by an interference-based model which agrees with the experimental conclusions, mainly obtained by various forms of microscopy. Statistical approach based on the autocorrelation function gives quantitative description about the quality of the order in the periodic structure and about the nanoparticles averaged diameter (80 nm). We also present the optical extinction spectrum of the Laser Induced Periodic Surface Structure (LIPSS)-containing area of the glass, which unusually shows several bands in the visible range. The period of 160 nm of the periodic structure is short enough to allow coupling between nanoparticles, which makes it a possible candidate for plasmon-based optical applications

    SynthÚse de nouveaux ligands thiacalixaréniques et étude de leurs propriétés de complexation

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    8 pagesNational audienceLes perspectives ouvertes par la chimie supramolĂ©culaire sont immenses notamment dans le domaine biomimĂ©tique mais aussi Ă  l'interface avec la physique et la science des matĂ©riaux. Dans ce contexte nous nous sommes intĂ©ressĂ©s Ă  une famille de macrocycles synthĂ©tiques appelĂ©s thiacalixarĂšnes. De nouveaux ligands ont Ă©tĂ© prĂ©parĂ©s et leurs propriĂ©tĂ©s de complexation ont Ă©tĂ© Ă©tudiĂ©es vis-Ă -vis de mĂ©taux lourds et de mĂ©taux de transition. Ces rĂ©cepteurs ont Ă©tĂ© conçus de telle façon qu'ils puissent ĂȘtre fixĂ©s sur des supports, leur permettant alors d'ĂȘtre utilisĂ©s en phase solide – liquide

    Graphene-based textured surface by pulsed laser deposition as a robust platform for surface enhanced Raman scattering applications

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    International audienceWe have developed a surface enhanced Raman scattering (SERS)-active substrate based on gold nanoparticles-decorated few-layer (fl) graphene grown by pulsed laser deposition. Diamond-Like Carbon film has been converted to fl-graphene after thermal annealing at low temperature. The formation of fl-graphene was confirmed by Raman spectroscopy, and surface morphology was highlighted by scanning electron microscopy. We found that textured fl-graphene film with nanoscale roughness was highly beneficial for SERS detection. Rhodamine 6G and p-aminothiophenol proposed as test molecules were detected with high sensitivity. The detection at low concentration of deltamethrin, an active molecule of a commercial pesticide was further demonstrated

    Invariant NKT Cells Suppress CD8+ T-Cell–Mediated Allergic Contact Dermatitis Independently of Regulatory CD4+ T Cells

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    Invariant natural killer T (iNKT) cells expressing a CD1d-restricted invariant αÎČTCR have key regulatory roles in autoimmunity, pathogen immunity, and tumor surveillance, but their function in the control of allergic skin diseases remains poorly documented. Using a model of contact hypersensitivity (CHS) to the hapten DNFB, we show here that iNKT cell deficiency results in enhanced skin inflammation due to augmented hapten-specific IFN-Îł-producing CD8+ effectors in skin draining lymph nodes (dLNs) and their massive recruitment into the allergen-exposed skin. Adoptive transfer and antibody depletion experiments as well as in vitro studies revealed that iNKT cells (1) reduce the severity of CHS, even in presensitized mice, (2) require hapten presentation by CD1d+ dendritic cells (DCs) to dampen skin inflammation, and (3) produce IL-4 and IL-13 after CD1d-dependent in vitro stimulation by hapten-loaded DCs only in the presence of IFN-Îł released from activated CD8+ effector T cells. In corollary, mice double deficient in IL-4 and IL-13 exhibit an exacerbated CHS. Finally, iNKT-suppressive function is independent of Foxp3+ regulatory T cells (Tregs). These data highlight that, besides Foxp3+ Tregs, iNKT cells are potent downregulators of CD8+ T cell–mediated CHS, and underscore that both cell types are important for the regulation of allergic skin inflammation

    Surfaces fonctionnalisées à base de nanoparticules métalliques pour l'optique et la photonique

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    Dans le cadre de cette thÚse, nous avons développé une technique expérimentale basée sur un traitement laser ultraviolet continu permettant la croissance de nanoparticules (NP) d argent et/ou d or dans des verres soda-lime préalablement dopés aux ions Ag+ et/ou Au3+. L originalité de cette méthode réside dans la trÚs forte photosensibilité du verre à la longueur d onde utilisée (244 nm), par rapport aux résultats de la littérature. Dans les verres échangés à l argent, des NP de grand diamÚtre (jusqu à 250 nm) et trÚs concentrées ont été obtenues et le mécanisme de leur formation a été explicité. Nous avons ensuite montré que les substrats ainsi fabriqués sont adaptés pour la détection d espÚces chimiques faiblement concentrées via l effet de diffusion Raman exaltée de surface, en choisissant comme molécule test la rhodamine 6G, ce qui était le but initial de ce travail. Nous nous sommes ensuite intéressés à la nanostructuration du verre par des NP d argent : ainsi, des lignes de NP (de diamÚtre 80 nm), périodiquement espacées de 160 nm ont été obtenues pour des durées d insolation suffisamment longues . AprÚs avoir caractérisé expérimentalement ces arrangements périodiques de NP d argent, nous avons montré un trÚs bon accord entre nos résultats expérimentaux et la théorie classique des ripples (ou modÚle de Sipe). Ce résultat est sans aucun doute le plus original de ce travail de thÚse. D autre part, nous avons montré que l insolation laser à 244 nm permet la croissance de NP d or de diamÚtre 50 nm dans les verres dopés Au3+ par poling thermique. Le codopage du verre avec des NP d argent et d or a également été obtenuIn this thesis, we have developed an experimental method based on the use of a continuous ultraviolet laser to process a soda-lime glass doped with either Ag+ or Au3+ ions for the growth of silver and/or gold nanoparticles (NP). The main advantage of method lies in the very high photosensitivity of the glass at the laser wavelength (244 nm), compared to the results of the literature. In silver-exchanged soda-lime glasses, highly concentrated silver NP of large diameter (up to 250 nm) have been obtained and their growth is fully elucidated. We have then shown that these substrates are well-suited to get efficient surface enhanced raman scattering effect with rhodamine 6G as test molecule, which was the first aim of this thesis. A third part is then dedicated to the growth of periodic nanostructures embedded with silver NP at the surface of the glass. Silver NP (of average diameter 80 nm) are aligned along lines periodically spaced by 160 nm. After experimental characterization of these periodic arrangements, we have demonstrated very good agreement between these experimental results and classical ripples theory (known as Sipe s model in the literature).This result is undoubtedly the most original result of this manuscrit. We have then shown that laser exposure at 244 nm allows the growth of gold NP in soda-lime glass beforehand doped with Au3+ ions by thermal poling. Codoping of the glass containing with both silver and gold nanoparticles has also been achievedST ETIENNE-Bib. électronique (422189901) / SudocSudocFranceF
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