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Essai d’une typologie statistique des pratiques pédagogiques déployées au sein des formations alternées
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Creation of Composite Aerogels Consisting of Activated Carbon and Nanocellulose Blended with Cross-Linked Biopolymers: Application as Ethylene Scavengers
No full textInternational audienceThis study involved producing aerogels using activated carbon (AC) and nanocellulose (NC). Two distinct structured composites, AC composite aerogel (ACCA) and NC composite aerogel (NCCA), were developed by separately mixing AC and NC with identical proportions of cross-linked biopolymers: hydroxypropyl methylcellulose (HPMC), methylcellulose (MC), and chitosan (C). These aerogels were evaluated for their capability to adsorb ethylene gas through batch experiments, while the physical and chemical characteristics were thoroughly examined to determine their feasibility of removing ethylene. The resulting ACCA and NCCA aerogels exhibited low densities of 0.094 g cm−3 and 0.077 g cm−3, respectively, coupled with high porosity ranging between 95 and 96%. During the ethylene adsorption test, NCCA exhibited superior ethylene removal rates (~14.88–16.77 mL kg−1) compared to ACCA (~13.57–14.97 mL kg−1). Specifically, NCCA achieved a removal efficiency of 83.86% compared to 74.64% for ACCA. Kinetic model fitting yielded high R2 values ranging from 0.97 to 0.98 with the Lagergren kinetic model. These findings suggest the potential of composite aerogels to be incorporated into food packaging materials for dynamic ethylene capture, independent of environmental conditions, thereby providing promising routes for further development
L’activité réflexive des agents de terrain lors d’un dispositif de formation hybride qui intègre de la réalité virtuelle
No full textInternational audienceThis article examines the reflexive activity of field agents in a training device created for the nuclear industry. Designed by the researchers and a trainer, this device, known as scenario-inquiry, is intended to help trainees gain an understanding of the spatial and functional characteristics of a complex industrial building, essential knowledge for their future job as field operators. The device might be described as hybrid in the sense that it combines various teaching spaces and methods (a virtual environment for trainees to browse, an onsite training workplace, a traditional classroom) as well as several technical objects (a complete 3D digital model of the building, full-scale models of valves and operational technical documentation used in work situations). The semio-logical analysis stemming from the course-of-action framework, and its dialogical relationship with Peirce’s semiotics, serve as the foundation for understanding the operators’ training activities. Abduction, deduction, and induction are the three types of inference that define their interpretative activity when using the scenario-inquiry device. Abductive inference is the process of formulating explanatory hypotheses enabling the discovery and creation of novelty. Our results indicate (i) the determining role of abductive reasoning in the creation, reinforcement, invalidation and connection of knowledge, and (ii) the essential role of analogies in the linking of acquired knowledge and new knowledge by abduction. This article offers the opportunity to critically examine training scenarios that place emphasis on inductions and deductions. Offering educational resources that support abductive reasoning—such as “curiosity laboratories,” which are learning settings that inspire people to explore and go beyond the boundaries of what is expected of them—would be ideal. This will encourage trainees to switch between a range of semiotic registers.Cet article traite de l’activité réflexive de formés dans un dispositif de formation conçu pour les agents de terrain de l’industrie nucléaire. Ce dispositif, nommé scénario-enquête, est le produit d’une démarche de recherche orientée par la conception, qui vise à aider les stagiaires à s’approprier les caractéristiques spatiales et fonctionnelles d’un bâtiment industriel complexe, dont la connaissance est cruciale pour leur futur métier d’agent de terrain. Ce dispositif peut être qualifié d’hybride au sens où il combine différents espaces et modalités pédagogiques (un environnement virtuel dans lequel naviguent les stagiaires, un chantier-école, une salle de formation) et objets techniques (un modèle numérique 3D complet du bâtiment, des maquettes de matériel à échelle 1, des vannes, de la documentation technique opérationnelle utilisés en situation réelle). L’analyse de l’activité réflexive des formés s’appuie sur l’analyse sémiologique développée dans le cadre du programme cours d’action, et dans ses rapports dialogiques avec la sémiotique de Peirce. Ainsi, l’activité réflexive qui se manifeste lors de l’utilisation du dispositif scénario-enquête est modélisée à l’aide de trois catégories d’inférences : abduction, déduction et induction. Les résultats suggèrent (i) un rôle important des raisonnements à dominante abductive dans la construction, renforcement, invalidation et mise en relation des connaissances, et (ii) un rôle déterminant des analogies dans la mise en relation des connaissances acquises et de nouvelles connaissances par abduction. Cet article offre l’occasion de questionner les situations de formation qui privilégient principalement les inductions et les déductions. Il serait préférable de proposer des outils pédagogiques qui encouragent les raisonnements d’abduction, comme des « laboratoires de curiosités », espaces qui incitent à la découverte et permettent d’aller au-delà des connaissances attendues, favorisant ainsi l’alternance entre différents registres sémiotiques
Segmentation sémantique d’images visibles en cultures associées
No full textNational audienceL'utilisation des techniques de Machine learning et d'intelligence artificielle (IA) pour promouvoir la gestion durable des systèmes de culture est au cœur de ce travail. L'objectif est de développer une approche innovante en combinant ces technologies numériques avec des capteurs simples utilisant l'imagerie visible pour surveiller l'évolution de l'état azoté de la céréale en cultures associées céréale/légumineuse. Cette approche repose sur une segmentation sémantique avec le modèle DeepLabV3+, une technique de Deep Learning. Actuellement les outils disponibles pour évaluer ces besoins sont des pinces ou chlorophylle-mètres (SPAD, n-Tester) qui reposent sur des mesures optiques, mesures indirectes de la teneur en azote des plantes. Ces mesures par contact avec les feuilles sont fastidieuses pour un suivi dynamique au champ. Cela a conduit à explorer l’approche par imagerie visible plus simple techniquement mais qui nécessite une segmentation de l’image pour identifier la culture afin d’évaluer son état azoté
Adsorption of β-Lactoglobulin on Thiol-Functionalized Mesoporous Silica
No full textInternational audienceSBA-15 mesoporous materials were synthesized with different pore sizes (5 and 10 nm) and thiol-functionalized groups and then characterized to describe their ability to differentially adsorb β-lactoglobulin (BLG), a globular protein with an ellipsoid shape measuring 6.9 nm in length and 3.6 nm in width. All adsorption experiments showed that the adsorption capacities of mesoporous materials for BLG were dependent of the duration of contact between the two materials (mesoporous and BLG) and the initial BLG concentration. It was also shown that the pore sizes and thiol groups of SBA-15-based adsorbents are an important factor for the BLG adsorption capacities. Among the tested adsorbents, thiol-functionalized SBA-15 with 10 nm pore size (SBA-15-SH-10) showed the highest adsorption capacity (0.560 g.g-1) under optimal experimental conditions. Kinetics studies demonstrated that the adsorption occurs predominantly inside the pores with interactions occurring on heterogeneous surfaces. In addition, the thermodynamic parameters indicate a spontaneous and exothermic behavior of BLG adsorption process onto the thiol-functionalized SBA-15 mesoporous adsorbent. Finally, the characterization of SBA-15-SH-10 adsorbent at 308 K showed the occurrence of an oxidation reaction of the thiol groups to sulfonate groups during the adsorption process as confirmed by Raman spectroscopy. The spectra recorded after adsorption of the protein showed that this adsorption did not impact the secondary structure of the protein
The bottleneck/cork interface: a key parameter in bottle-aging of wine
No full textInternational audienceA study of changes in oxygen transfer through micro-agglomerated corks was carried out over 24 months under controlled storage conditions (Chanut et al., 2023a). This work demonstrated that the glass/cork interface can represent a major entry route for oxygen into wine bottles. It also showed that there is no difference in oxygen transfer at 20°C between bottles stored horizontally and vertically. However, high storage temperature greatly increases oxygen transfer at the interface between the cork and the bottleneck
Comparison of natural and agglomerated cork stoppers in dry and soaked states.
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Potential uses of sodium alginate as a coating material for next-generation probiotics.
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Hysteretic response of N2O reductase activity to soil pH variations after application of lime to an acidic agricultural soil
No full textInternational audienceNitrous oxide (N2O) contributes to increasing the greenhouse effect and is also involved in stratospheric ozone depletion. In soil and water, N2O reductase catalyses the reduction of N2O into the inert form N2 and is then considered as a key environmental enzyme. N2O reductase activity is known to be affected by acidic conditions (Samad et al. 2016) and the application of liming materials to acidic soils is now proposed as a solution for mitigating soil N2O emissions (Barton et al. 2013).During a one-year laboratory experiment, we studied the functioning of N2O reductase after the application of calcium carbonates to an acidic soil with initially a very low capacity to reduce N2O. The functioning of N2O reductase was characterised through anaerobic incubations using the acetylene inhibition technique combined with a logistic model to determine the main enzyme functioning characteristics (latency, maximal rate).Both changes in soil pH and soil capacity to reduce N2O were rapidly observed after the application of lime materials. The activity of N2O reductase was observed to be efficient throughout the experiment even when the soil had returned to initial acidic conditions, revealing a hysteretic response of N2O reductase to pH variations. Nevertheless, some signs of lower N2O reductase activity over time were observed mainly after 200 days of applying lime materials. Altogether, these results suggest that, in this soil condition, the beneficial impact of the application of liming materials on N2O emissions could last longer than this on soil pH
