HAL Portal UPPA (University of Pau and the Pays de l'Adour)
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Gilets jaunes et Anti-pass sanitaire : étude des obstacles à une coalition protestataire dans le centre de la France
No full textInternational audienceCette communication aborde les obstacles à une coalition protestataire durable entre des Gilets jaunes de la première heure et des nouveaux contestataires de la politique sanitaire lors des manifestations antipass. À partir de l’étude des mobilisations du second semestre de l’année 2021 dans une ville moyenne du centre de la France et sur les réseaux sociaux numériques, elle vise à dévoiler les conflits qui se nouent localement et constituent autant d’obstacles à une participation commune. Elle révèle que les participants sont tant divisés sur leurs revendications, qui reposent sur des dispositions idéologiques et politiques distinctes, que sur leurs conceptions de la manifestation comme mode de participation politique
Biomimetic mineralization of diatom exoskeleton for sustainable pH-sensitive colored chitosan/silica hybrid self-supported films
No full textInternational audienceA gentle bio-inspired approach to the biosilicification occurring in diatom frustule is proposed to develop, at room temperature and without addition of a co-solvent, self-supported hybrid organic/inorganic films with pH-sensitive properties. It was found that chitosan (CS) biopolymer, a polysaccharide possessing numerous amine groups (–NH2) is capable of mimicking the action of the silaffins proteins of diatom frustule in the polycondensation process of the TetraEthoxyOrthoSilicate (TEOS) silica precursor to form a cohesive self-supported hybrid film under soft conditions in aqueous media. Thanks to its good film-forming property, hybrid chitosan/silica (CS/SiO2) films have been elaborated varying the amount of TEOS to study their optical and mechanical properties. It is shown that increasing the amount of TEOS up to 90 wt% improves the transparency, strength and stability of the films due to the interpenetration of the chitosan and silicaq networks. The incorporation of sustainable pH-sensitive alizarin dye during the elaboration of the films does not affect their mechanical properties whatever the composition. Moreover, these colored hybrid materials show good pH-sensitiveness under basic environment. Therefore, thanks to their antimicrobial properties and their pH-sensitivity, such self-supported films could be designed for applications such as smart sustainable food packaging and food degradation indicator
Mid-Level data fusion techniques for gum rosin discrimination according to Pinus species, tapping methods, and geographic origins
No full textInternational audienceGum rosin, an essential industrial resource, is primarily derived from pine species, with significant demand across adhesives, coatings, and related industries. With the current growth trajectory of the global rosin market, ensuring product authenticity and quality is fundamental. This study focuses on authenticating gum rosin, specifically that extracted from P. pinaster in Southwest France using the BioGemme method, which is recognized for its purity due to a closed-cup tapping approach. Sixty-one gum rosin samples, representing three Pinus species, three tapping methods, and four geographical origins, were analyzed using a multi-method approach: Gas Chromatography-Flame Ionization Detection (GC-FID), standardized quality assessments, and Near-Infrared (NIR) spectroscopy. To achieve robust sample differentiation, Partial Least Squares-Discriminant Analysis (PLS-DA) was applied on individual blocks, as well as mid-level data fusion methods (SO-PLS-LDA and SO-CovSel-LDA), to combine the chemical composition, quality attributes, and NIR spectral fingerprints. Results reveal that data fusion significantly enhances the discriminative capacity, particularly with the SO-PLS-LDA model, reaching a cross-validated MCC of 0.98. Key chemical markers were identified, including diterpenes and resin acids, along with acid number from quality attributes and distinctive NIR fingerprints. This integrative approach underlines the added value of combining data sources for accurate gum rosin classification and highlights the potential for handheld NIR spectrometers as cost-effective tools for on-site discrimination. This work establishes a foundational methodology for standardized gum rosin discrimination and paves the way for future studies in industrial applications
In Situ Fabrication of Quasi-Solid Polymer Electrolytes for Lithium Metal Battery via Photopolymerization-Induced Microphase Separation
No full textInternational audienceThe photopolymerization-induced microphase separation (photo-PIMS) process involving a reactive polymer block was implemented to fabricate nanostructured quasi-solid polymer electrolytes (QSPEs) for use in lithium metal batteries (LMBs). This innovative one-pot fabrication enhances interfacial properties in LMBs by enabling in situ nanostructuring of QSPE directly onto the electrodes. This process also allows for customization of QSPE structural dimensions by tweaking the architecture and molar mass of poly[(oligo ethylene glycol) methyl ether methacrylate-co-styrene] (P(OEGMA-co-S)) macromolecular chain transfer agent. Bicontinuous nanoscale domains of soft P(OEGMA-co-S)/propylene carbonate/lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) phase and hard poly[isobornyl acrylate-co-(oligo ethylene glycol)diacrylate] phase furnished the QSPEs with respectively high ionic conductivity (0.34 mS cm-1 at 30 °C) and interesting level of mechanical strength (106-107 Pa at 30 °C). The as-prepared QSPE showed decent electrochemical properties and an electrochemical stability window of about 4.2 V vs Li+/Li. This electrolyte enables the Li||SPE||Li symmetric cell to cycle over 350 h at 0.1 mA cm-2 without evidence of dendrite formation. By means of galvanostatic cycling studies on a prototype lithium metal battery with LiNi0.8Mn0.1Co0.1O2 or LiFePO4 positive electrodes, we further demonstrate that the in situ nanostructured QSPE exhibited better performances than the corresponding stacked battery
Methylmercury degradation by hot spring sulfur-linked microbial communities as a dominant pathway in regulating mercury speciation
No full textInternational audienceSulfidic hot springs harbor unique microbial communities and are important in mercury (Hg) species transformations, although the fine scale drivers of these processes remain poorly understood. Here we studied Hg speciation in water, biofilms, and sediment across three sampling seasons in a French sulfidic hot spring with low Hg concentrations. Microbial Hg species methylation and demethylation potentials were evaluated using incubation experiments with species-specific Hg isotope tracers. Temporal variation in inorganic Hg (iHg) and methylmercury (MeHg) concentrations in water, biofilm, and sediment was observed. The incubation of microbial communities in biofilms and sediment under dark conditions exhibited low iHg methylation potentials, whereas a significant extent of biotic MeHg demethylation to oxidized iHg was found in relation to MeHg concentrations. Results from microbial diversity (16S rDNA) and the metabolic inhibition experiments suggest an important role of sulfur-linked bacterial metabolism dynamics. Specifically, sulfate-reducers and anoxygenic phototrophs were important factors in the regulation of MeHg concentrations in our study site. Overall, the observed dominance of microbial MeHg demethylation demonstrates a strong Hg detoxification capacity in sulfidic aquatic environments
Engagement de mères de quartiers populaires. (Main)tenir son engagement dans le temps: RT 48 - Articulation des temps sociaux
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L’exploration de la phase de spécification d’une recherche-intervention
No full textInternational audienceEn janvier 2024, une enquête met en évidence les difficultés croissantes rencontrées par les structures de l’Action Sociale pour remplir leurs missions, certaines allant jusqu’à envisager des suppressions de postes. Dans ce contexte d’urgence, des acteurs de l’économie sociale et solidaire, rejoints par des représentants des pouvoirs publics, se réunissent au sein d’un collectif d’organisation. Considéré comme une innovation organisationnelle, ce collectif émerge d’une dynamique de recherche de sens commun, de reconnaissance des limites d’action individuelles, et d’un effort partagé d’intelligibilité de la situation-problème. Ce processus fait apparaître un besoin d’accompagnement, perçu comme un levier d’innovation sociale et de gestion collective des ressources. Notre étude vise à caractériser la fonction pédagogique de ce processus d’accompagnement à travers une démarche de recherche-intervention. Elle s’appuie sur une dizaine d’heures d’entretiens, treize heures d’observation de terrain et une vingtaine d’analyses documentaires. Les résultats révèlent une co-construction de connaissances, nourrie par les principes épistémologiques de la recherche-intervention, et soulignent la dimension pédagogique de cette dernière dans un contexte de transformation organisationnelle
Electrification of Transportation - Decarbonization of mobility: The usefulness of deploying cradle-to-grave analysis in both a systemic and holistic approach. The case of air mobility
No full textInternational audienceDecarbonizing air mobility requires decarbonizing its energy sources. While biofuels will play an important role, other low-carbon energy carriers based on electricity are also being considered, such as battery electrification and liquid hydrogen (LH2), or efuel, an energy carrier based on dihydrogen. Each energy carrier has its own conversion steps and losses, as well as its own integration effects on the carrier. These combinations result in different energy requirements that must be carefully studied.As they are all based on electricity, this study compares these different energy carriers using the Life Cycle Analysis (LCA) methodology, from cradle to grave, in this case from well to rotor, when applied to a standard vertical take-off and landing (VTOL) air mobility mission.This new approach shows that the choice of energy vector dictates the architecture of the propulsion system, which has integration effects with the aircraft, ultimately significantly influencing the energy required for a given mission. Our conclusions highlight that for a given mission type, the amount of energy required can vary from 400 to 2,665 kWh depending on the energy vector chosen. These differences lead to significant variations in terms of operating costs and CO2eq emissions. In all scenarios, efuel is more efficient than LH2, while direct battery electrification remains penalized by its weight, limiting potential missions. We therefore conclude that using the most efficient molecule in an aircraft can offset the additional energy cost spent on the ground to synthesize it. Finally, we found that, for each of these energy carriers, it is actually the carbon intensity and the price of electricity that determine the operating cost and CO2eq emissions.The document includes:- Comparison of efficiencies (State of the Art 2030 projected for aeronautical application), before integration into the carrier.At this stage, the results are identical or very close to the main conclusions of articles published in the literature. However, it should be noted that the efuel energy vector, which has not yet been extensively studied, has been integrated.- Taking into account integration into the aircraft: methodology, equations, main assumptions. It is at this stage that the approach innovates: air mobility, particularly on VTOL (Vertical Take Off and Landing) missions, is very demanding, both in terms of mass and Cs. The end use of VTOL even more so (hovering).It is therefore necessary to understand the effects of integration into the aircraft, because the addition of extra mass (H2 tank and/or batteries, for example) requires more power, and therefore heavier engines with higher specific consumption, which means more energy needs to be carried for the same mission, and therefore larger tanks and/or batteries (and therefore more mass...): This “snowball” effect must be carefully calculated in order to understand the impacts on the propulsion system, its performance, and the resulting final consumption.- Results: We demonstrate that the choice of energy vector must be based on the end use. In the case of VTOL air mobility, when the energy used upstream is electricity (used either directly via batteries or for conversion into an energy vector, H2 or efuel), efuel is the least inefficient solution