Mécanismes locaux de déformation de l'acier inoxydable austénitique 316L

International audienceDans cette étude, nous présentons une approche nouvelle pour comprendre les mécanismes locaux de déformation.Les champs cinématiques obtenus à partir d’une grille nanoparticules d’orsont combinés aux mesures cristallographiques de la région de la grille. Les déformations dans les grains et aux joints de grains et l’apparition des glissements et leurs évolutions sont suivies. Ces résultats locaux sont comparés au comportement macroscopique fourni lors d’un essai de traction

The AVuPUR project (Assessing the Vulnerabiliy of Peri-Urbans Rivers): experimental set up, modelling strategy and first results

International audienceLe projet AVuPUR a pour objectif de progresser sur la compréhension et la modélisation des flux d'eau dans les bassins versants péri-urbains. Il s'agit plus particulièrement de fournir des outils permettant de quantifier l'impact d'objets anthropiques tels que zones urbaines, routes, fossés sur les régimes hydrologiques des cours d'eau dans ces bassins. Cet article présente la stratégie expérimentale et de collecte de données mise en ½uvre dans le projet et les pistes proposées pour l'amélioration des outils de modélisation existants et le développement d'outils novateurs. Enfin, nous présentons comment ces outils seront utilisés pour simuler et quantifier l'impact des modifications d'occupation des sols et/ou du climat sur les régimes hydrologiques des bassins étudiés. / The aim of the AVuPUR project is to enhance our understanding and modelling capacity of water fluxes within suburban watersheds. In particular, the objective is to deliver tools allowing to quantify the impact of anthropogenic elements such as urban areas, roads, ditches on the hydrological regime of suburban rivers. This paper presents the observation and data collection strategy set up by the project, and the directions for improving existing modelling tools or proposing innovative ones. Finally, we present how these tools will be used to simulate and quantify the impact of land use and climate changes on the hydrological regimes of the studied catchments

Early contributors, cooperation and fair rewards in crowdfunding

We address the issue of rewarding fairly contributors participating in a funded crowdfunding project. We develop a theoretical non-strategic model of crowdfuding and introduce on a new reward rule, which specifies the individual rewards obtained by the contributors as a function of both their financial contributions and the timing of these contributions. Our model share some similarities with other models of ressource sharing in which the axiomatic method is frequently used. Taking this approach, we characterize this new reward rule by a pair of natural axioms, and it turns out that the resulting rewards coincide with the Shapley value of a suitable cooperative game built from the crowdfunding project. This allocation rule conveys what we call the signaling effect: if two contributors make the same financial contribution, then the earlier of the two obtains a greater reward. In specific but relevant cases, we provide extra properties of this reward rule

Nanogauges gratings for strain determination at nanoscale

International audienceThe comprehension of deformation mechanisms and polycrystalline alloy properties is of great importance in materials science. One major challenge remains the measurements of the mechanical field components at the nanoscale. For the past twenty years, the development of nanotechnologies had a great impact on various scientific domains. Here we propose to take advantage of nanotechnologies in order to perform major breakthroughs in material strain determination. Indeed, in this study we investigate the use of metallic nanoparticles gratings to map local strains at the surface of materials. Nanoparticles can play the role of nanogauges, giving access to surface strains at the nanoscale by tracking their displacements during tensile tests performed under Scanning Electron Microscope (SEM). This original method is particularly helpful to map surface strains but also to evidence local heterogeneities as well to provide a direct comparison between local and macroscopic mechanical fields evolution. Therefore, this approach should be considered as an alternative technique both for academic and industrial researchers

Advanced digital image analysis method dedicated to the characterization of the morphology of filamentous fungus

International audienceFilamentous fungi have a complex morphology that induces fermentation process development issues, as a consequence of viscosity increase and diffusion limitations. In order to better understand the relationship between viscosity changes and fungus morphology during fermentations of Trichoderma reesei, an accurate image analysis method has been developed to provide quantitative and representative data for morphological analysis. This method consisted of a new algorithm called FACE that allowed sharp images to be created at all positions, segmentation of fungus, and morphological analysis using skeleton and topological approaches. It was applied and validated by characterizing samples of an industrial strain of Trichoderma reesei that had or had not been exposed to an extreme shear stress. This method allowed many morphological characteristics to be identified, among which nine relevant criteria were extracted, regarding the impact of shear stress on the fungus and on the viscosity of the fermentation medium

Nouveaux outils et nouvelles pratiques pour appréhender l'espace-temps fluvial

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IL-15 superagonist RLI has potent immunostimulatory properties on NK cells: implications for antimetastatic treatment

International audienceBackground As the immune system is compromised in patients with cancer, therapeutic strategies to stimulate immunity appear promising, to avoid relapse and increase long-term overall survival. Interleukin-15 (IL-15) has similar properties to IL-2, but does not cause activation-induced cell death nor activation and proliferation of regulatory T cells (Treg), which makes it a serious candidate for anticancer immunotherapy. However, IL-15 has a short half-life and high doses are needed to achieve responses. Designed to enhance its activity, receptor-linker-IL-15 (RLI) (SO-C101) is a fusion molecule of human IL-15 covalently linked to the human IL-15Rα sushi+ domain currently assessed in a phase I/Ib clinical trial on patients with advanced/metastatic solid cancer. Methods We investigated the antimetastatic activity of RLI in a 4T1 mouse mammary carcinoma that spontaneously metastasizes and evaluated its immunomodulatory role in the metastatic lung microenvironment. We further characterized the proliferation, maturation and cytotoxic functions of natural killer (NK) cells in tumor-free mice treated with RLI. Finally, we explored the effect of RLI on human NK cells from healthy donors and patients with non-small cell lung cancer (NSCLC). Results RLI treatment displayed antimetastatic properties in the 4T1 mouse model. By characterizing the lung microenvironment, we observed that RLI restored the balance between NK cells and neutrophils (CD11b + Ly6G high Ly6C low ) that massively infiltrate lungs of 4T1-tumor bearing mice. In addition, the ratio between NK cells and Treg was strongly increased by RLI treatment. Further pharmacodynamic studies in tumor-free mice revealed superior proliferative and cytotoxic functions on NK cells after RLI treatment compared with IL-15 alone. Characterization of the maturation stage of NK cells demonstrated that RLI favored accumulation of CD11b + CD27 high KLRG1 + mature NK cells. Finally, RLI demonstrated potent immunostimulatory properties on human NK cells by inducing proliferation and activation of NK cells from healthy donors and enhancing cytotoxic responses to NKp30 crosslinking in NK cells from patients with NSCLC. Conclusions Collectively, our work demonstrates superior activity of RLI compared with rhIL-15 in modulating and activating NK cells and provides additional evidences for a therapeutic strategy using RLI as antimetastatic molecule

Nouveaux outils et nouvelles pratiques pour appréhender l'espace-temps fluvial

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Investigation of nanoscale strains at the austenitic stainless steel 316L surface : Coupling between nanogauges gratings and EBSD technique during in situ tensile test

International audienceThe understanding of the mechanical properties at the microstructure scale is a key factor for the material macroscopic behavior comprehension and its appropriate engineering at the scale of the structure. In this study, a new approach which is based on the combination of both nanogauges displacements monitoring and electron backscatter diffraction (EBSD) techniques performed under Scanning Electron Microscope (SEM) during in-situ tensile tests is proposed. Strain evolutions at the microstructure components and the behavior of the material can be compared to the crystallographic data. The approach was applied to austenitic stainless steel 316L specimen in order to bring a proof of concept and put into evidence its potential. Among the information of interest which can be obtained through this technique, one can cite the possibility to highlight the strain initiations in the vicinities of twins and their evolutions during the tensile test or to evidence the strain heterogeneities at the surface of the specimen and its influence over the elongations and rotations of the microstructure components, which tends to be reorganized in order to balance the mechanical stress. Besides, such heterogeneities can be expressed in terms of misorientations and quantified from the EBSD data. The twinning and slip activities can also be correlated to the hardening of the material thanks to this method of characterization. As for its interest for characterizing the plastic domain, the technique can show how some grains may activate more than one slip system. Finally, it has been here demonstrated how complementary and powerful the combination of these two techniques may be considered and how it may give access to a better understanding of the material microstructure properties