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From surface damage to subsurface evolution: A multiscale microstructural analysis of grease-lubricated bearings under false brinelling
No full textInternational audienceFew studies dedicated to the service life of thrust bearings have mostly focused on surface wear, without investigating subsurface microstructural changes or establishing any correlation between these evolutions and the underlying wear mechanisms. This study investigates wear mechanisms and microstructural changes in grease-lubricated thrust ball bearings under false brinelling. Perfluorinated grease degradation increases friction and shear, promoting adhesive and oxidative wear. KAM and EBSD analyses reveal plastic deformation localized in martensite, with fragmentation. To enable a finer analysis of subsurface damage, techniques such as TEM and SAED analyses show nanostructuring of martensite near the surface and carbide-matrix interactions without decohesion. Inter-carbide spacing measurements and TEM cross-sections confirm carbide clustering in high shear zones. Reorientation of carbides under false brinelling stresses favors crack propagation. Partial carbide dissolution, identified via TEM, leads to iron and carbon diffusion into the martensite, increasing hardness and brittleness. This promotes crack initiation, flaking, and debris formation, which intensify local stresses. These results highlight the interplay between lubrication efficiency, microstructural evolution, and damage mechanisms
Artificial selection of suppressive or conducive rhizosphere microbiota circumvents the growth-defense trade-off due to a foliar pathogen
No full textInternational audiencePlant-pathogen interactions are influenced by physiological responses and rhizospheric microorganisms, which can create disease-suppressive or disease-conducive soils affecting pathogen dynamics. This study used artificial selection to shape soil microbiota conditioned by Arabidopsis thaliana to either suppress or promote the foliar pathogen Pseudomonas syringae DC3000 (Pst). Over successive iterations, plants were inoculated with Pst, and soils were selected based on plant symptoms: enhanced resistance (suppressive), increased susceptibility (conducive), or no selection (control). A non-inoculated group (non-conditioned) was also included. Disease symptoms, Pst proliferation, and rhizosphere microbiota were monitored each iteration. Selection for suppressive soils reduced disease severity and Pst levels, while conducive soils showed the opposite. Each soil type was enriched in distinct bacterial communities. A growth-defense trade-off was evident in control soils but less so in selected soils. Gene expression analysis revealed that plant hormone homeostasis, especially salicylic acid (SA) and jasmonic acid (JA) played key roles with SA linked to local defense and JA to systemic responses. This work highlights artificial selection as a promising strategy to modulate soil microbiota, influencing plant-pathogen interactions and microbial dynamics
Analysis of a degenerate parabolic system for cell dynamics in intestinal crypts
No full textIn this work, we study a system of degenerate parabolic equations modeling the dynamics of multiple cell populations in intestinal crypts. The model describes cell division, differentiation, and migration through a strongly coupled system of reaction-cross-diffusion equations with degenerate diffusion. By working with initial data in BV , we first consider a regularized form of the system and establish uniform BV estimates. Using these bounds, we then pass to the limit to obtain the existence of weak solutions
IA: Techniques, éthique, réglementation et bonnes pratiques
No full textArtificial intelligence is disrupting human organizations. To preserve them and make the most of this integration, professionals must guard against abstract goals, false commercial promises, and vaguely informative information. Because every information system, every team, and every technical and professional environment differs profoundly, the authors sought out informative feedback from the field with a view to developing desirable AI. In this book, they formulate best practices, discarding contradictory options and the speculation surrounding them.Beyond profitability calculations, the book emphasizes informed judgment, personal responsibility, and long-term control of artificial intelligence. Grounded in practice, it guides readers toward sustainable choices that are mindful of their impact on resources and living ecosystems.The book is intended for all decision-makers, technical or otherwise, who are committed to promoting desirable, efficient, and globally beneficial AI.L'intelligence artificielle vient bouleverser les organisations humaines. Pour les préserver et tirer le meilleur parti de cette intégration, le professionnel doit se garder des objectifs abstraits, fausses promesses commerciales, comme des informations vaguement instructives. Parce que chaque système d'information, chaque équipe, chaque environnement technique et professionnel diffère profondément, les auteurs sont partis à la recherche des retours de terrain instructifs en vue d'une IA souhaitable. Dans ce livre, ils formulent ces bonnes pratiques, écartant les options contradictoires ainsi que les spéculations qui les entourent.Au-delà des calculs de rentabilité, l’ouvrage met l'accent sur le jugement éclairé, la responsabilité personnelle et la maîtrise à long terme de l’intelligence artificielle. Ancré dans la pratique, il oriente vers des choix durables, conscients de leur impact sur les ressources et les équilibres vivants.L'ouvrage s'adresse à tous les décideurs, techniciens ou non, décidés à promouvoir une IA souhaitable, efficiente et globalement bénéfique
Traitement par champ électrique pulsé de racines d'endives forcées : amélioration de l'extraction et validation à l'échelle pilote
No full textInternational audienceForced endive roots (Cichorium intybus L.), usually discarded after forcing, represent a valuable biomass rich in carbohydrates and bioactive molecules. This study investigated the use of Pulsed Electric Field (PEF) treatment to enhance the diffusion of intracellular solutes from forced endive root tissues and to support the development of a scalable extraction process. Roots were treated at different PEF intensities (2.98–142.4 kJ/kg), and soluble- matter diffusion was evaluated at 20°C and 70°C. PEF significantly accelerated solute release compared with untreated samples, with 28.44 kJ/kg and 142.4 kJ/kg intensities achieving the highest °Brix values at both temperatures despite their markedly different cell disintegration levels. Based on diffusion performance, energy efficiency, and structural responses, 28.44 kJ/kg intensity level was selected for upscaling. Pilot-scale experiments (diffusion at ambient temperature) confirmed the laboratory trends, with the upscaled PEF treatment matching the diffusion kinetics of the selected laboratory condition and yielding a 2.47-fold increase in soluble sugars compared with untreated samples. Textural analyses showed that PEF treatment induced significant tissue softening, consistent with electroporation-driven structural weakening, while maintaining tissue integrity better than freeze-thawing. In conclusion, PEF demonstrated strong potential as an energy-efficient, scalable technology for the carbohydrate-oriented valorization and fermentation-based applications
Élaboration de films polyesters biosourcés et évaluation de leur biodégradabilité en digestion anaérobie
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Accompagner la certification AFAQ : création d'un outil d'autodiagnostic
No full textThis document presents a project to support AFAQ Biomedical Service certification, carried out as part of a Master's degree in Health Engineering. AFAQ Biomedical Service certification is part of an approach to structuring and recognising quality within healthcare establishments. While the challenges of quality and safety in medical devices are recognised, their practical implementation remains complex due to the organisational, human and financial constraints that must be taken into account in each biomedical department.This project is based on the study of the AFAQ standard, its requirements and its links with ISO 9001, in order to help biomedical services identify ways to improve their practices. The work focuses in particular on process structuring, activity traceability and document management.To assist biomedical departments in their efforts, we have created a tool to support and assist with self-diagnosis of compliance with AFAQ requirements. This tool, designed in HTML format, enables departments to assess their level of compliance, identify areas for improvement and prepare effectively for certification, while complying with the usage and safety constraints of the hospital environment.Dans le cadre du projet d'accompagnement à la certification AFAQ Service Biomédical Niveau 2, nous tenons à exprimer toute notre reconnaissance à toutes les personnes ayant contribué à la réussite de ce travail. Nos remerciements les plus sincères vont à Monsieur Pol-Manoel Felan, notre encadrant, pour son suivi rigoureux, ses conseils avisés et la qualité de son accompagnement. Sa disponibilité, son sens de l'écoute et sa parfaite maîtrise du domaine biomédical ont été des atouts précieux pour guider nos réflexions et structurer notre démarche. Nous exprimons notre gratitude envers Monsieur Gilbert Farges pour les précieux conseils qu'il a su nous prodiguer ainsi que le temps qu'il nous a accordé. Ses connaissances sur la certification AFAQ nous ont été d'une grande aide. Nous tenons également à remercier Mesdames Isabelle Claude et Julie Follet pour leur encadrement global, leur disponibilité et leur rôle fédérateur tout au long de ce projet. Leur accompagnement a permis de maintenir une cohérence d'ensemble et une dynamique de groupe constructive. Enfin, nous adressons nos remerciements à toutes les personnes, internes ou externes, ayant contribué, de près ou de loin, à la concrétisation de ce travail. Grâce à leur implication et à leurs échanges, nous avons pu approfondir notre compréhension du fonctionnement d'un service biomédical et de la démarche de certification AFAQ, tout en développant une approche à la fois méthodique, collaborative et enrichissante
From lyotropic to thermotropic behavior: solvent-free liquid crystalline phases in polymer–surfactant-conjugated rod-shaped colloidal viruses
No full textInternational audienceFilamentous bacteriophages fd are viral particles, highly monodisperse in size, that have been widely used as a model colloidal system for studying the self-assembly of rod-shaped particles as well as a versatile template in nanoscience. In aqueous suspensions, fd viruses exhibit lyotropic behavior, forming liquid crystalline phases as their concentration increases. Here, we report a solvent-free system displaying thermotropic phase behavior, achieved through covalent coupling of low molecular weight PEG-based polymer surfactant onto the fd virus surface. Upon lyophilization of aqueous suspensions of these polymer-grafted bacteriophages and subsequent thermal annealing, a solvent-free material is obtained, exhibiting both viscoelasticity and, notably, thermotropic liquid crystalline properties. A combination of small-angle X-ray scattering and optical microscopy experiments reveals the formation of an ordered hexagonal mesophase below 30 °C, which undergoes a melting transition into an isotropic liquid at higher temperatures. Our results demonstrate an efficient approach for converting lyotropic into thermotropic phase behavior in the columnar liquid crystalline phase of filamentous fd colloids. This approach paves the way for extending such functionalization to other technologically relevant rod-like systems, such as carbon nanotubes and cellulose nanocrystals, enabling the introduction of thermotropic properties in anhydrous colloidal materials
Contraintes économiques, innovations sociales et stratégies de résilience : De l'art à l'entreprise !
No full textInternational audienceRecent developments in entrepreneurship studies mark a significant turning point in how we understand creative trajectories and the economic practices associated with art. By moving away from the heroic figure of the solitary entrepreneur and valuing everyday entrepreneurship (Welter & Baker, 2017; Welter & Baker, 2020), research is now opening up to situated, collective, and experiential practices. This theoretical shift allows us to integrate forms of artistic entrepreneurship (Emin & Schieb-Bienfait, 2025) as existential and social quests, where creation becomes simultaneously an economic, aesthetic, and political act.From this perspective, fine craftsmanship emerges as a privileged field of observation. These practices, often marginal or precarious (Alper & Wassal, 2006; Comunian & England, 2020), embody the tension between symbolic commitment and economic survival, while revealing the logics of resilience and cooperation that structure local creative ecosystems.This text proposes to explore this articulation through the case of Pernes-les-Fontaines, a village designated a "City of Art and Crafts" since 1998, by comparing it with research conducted on another designated city: Pézenas (Loup, 2003).L’évolution récente des études sur l’entrepreneuriat marque un tournant significatif dans la manière d’appréhender les trajectoires créatives et les pratiques économiques associées à l’Art. En s’éloignant de la figure héroïque de l’entrepreneur solitaire pour valoriser les formes de l’entrepreneuriat du quotidien (everyday entrepreneurship, Welter & Baker, 2017 ; Welter & Baker, 2020), la recherche s’ouvre désormais à des pratiques situées, collectives et sensibles. Ce déplacement théorique permet d’intégrer les formes d’entreprenance artistique (Emin & Schieb-Bienfait, 2025) comme des quêtes existentielles et sociales, où la création devient à la fois un acte économique, esthétique et politique.Dans cette perspective, l’artisanat d’art se présente comme un champ privilégié d’observation. Ces pratiques, souvent marginales ou précaires (Alper & Wassal, 2006 ; Comunian & England, 2020), incarnent la tension entre engagement symbolique et survie économique, tout en révélant les logiques de résilience et de coopération qui structurent les écosystèmes créatifs locaux.Ce texte propose d’explorer cette articulation à travers le cas de Pernes-les-Fontaines, village labellisé « Ville et Métiers d’Art » depuis 1998, en le confrontant aux travaux faits sur une autre ville labellisée : Pézenas (Loup, 2003)
Stochastic inference of effective material properties from crystallographic textures via Gaussian process regression
No full textInternational audienceThis work investigates the impact of measurement uncertainty in polycrystalline texture data on homogenized material properties through full-field homogenization. Crystallographic texture, represented by Pole Density Functions, is modeled through Gaussian Process (GP) regression, in which measurement error is explicitly introduced via the noise term of the GP. Two uncertainty propagation approaches are examined. In the first, deterministic descriptors derived from the GP posterior distribution, namely the posterior mean and the bounds of the 95% confidence interval, are used as texture inputs for homogenization. In the second, Monte Carlo Pole Density Function instances are sampled directly from the GP posterior distribution and propagated through homogenization. Numerical experiments on a two-dimensional thermal conduction problem use a synthetic texture. The effective properties and their variability obtained from both approaches are compared with deterministic predictions based on the error-free reference texture. The results show that sampling-based homogenization provides a more robust estimation of effective physical properties and their associated uncertainty