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RSM-BBD optimization of room-temperature synthesized ZIF-8 for synergistic adsorption-photocatalysis of RhB
No full textInternational audienceThree ZIF-8 nanomaterials with different Zn : 2-methylimidazole molar ratios (1 : 30, 1 : 50, and 1 : 70) were synthesized at room temperature in aqueous medium within 30 minutes without surfactants. Structural analyses confirmed the formation of mesoporous ZIF-8 with distinct morphologies, ranging from spherical assemblies to rhombic dodecahedra. Response Surface Methodology using a Box-Behnken design (RSM-BBD) was applied to optimize five parameters (pH, contact time, pollutant dose, linker amount, and catalyst weight) governing rhodamine B (RhB) removal. Under optimized conditions (pH 7, 70 mg catalyst, 10 ppm RhB, 60 min contact), ZIF-8 with a 1 : 70 ratio achieved a maximum adsorption capacity of 91.7 mg g-1 and a removal efficiency of ∼91%, fitting well with the Langmuir model (R 2 = 0.97). Photodegradation studies revealed high activity under UV irradiation, with rate constants of 0.00812, 0.00215, and 0.0014 min-1 for ZIF-8 (1 : 30, 1 : 50, and 1 : 70), respectively. The materials also demonstrated excellent recyclability, retaining over 92% efficiency after five cycles. The novelty of this work lies in the systematic evaluation of the Zn : 2-Hmim molar ratio on the morphology and performance of ZIF-8, combined with the first application of RSM-BBD to optimize the dual adsorption-photodegradation process for RhB removal. These findings provide new insights into tailoring ZIF-8 synthesis for efficient wastewater treatment applications
Influence des conditions sur la température observée lors du détourage de composites à renfort en fibres de lin
No full textInternational audienceInfluence des conditions sur la température observée lors du détourage de composites à renfort en fibres de li
AI or I? Exploring Student Learning And Emotional Responses To AI Use In Hospitality And Tourism Education
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Précisions autour du point de départ du délai de prescription du préjudice d'anxiété des travailleurs de l'amiante
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Determining Relevant 3D Roughness Parameters for Sandblasted Surfaces: A Methodological Approach
No full textInternational audienceThis study presents a robust methodology for analyzing 3D roughness parameters to characterize sandblasted surfaces, identifying the most relevant descriptors for process optimization. Sandblasting with irregularly shaped corundum particles is performed using five grit sizes (25, 50, 90, 125, and 250 µm) and three pressure levels (2, 3, and 4 bar). The resulting surfaces are characterized through eight 3D roughness parameters: Sa, Spc, Sal, Sfd, Sdq, Sdr, Spd, and Str. A linear model of the form Q = a + b.D + d.D.P, where Q represents the roughness parameter, D is the average grit size, and P is the sandblasting pressure, is employed. For Spd, a nonlinear model, Spd = (a + b.D + d.D.P)2, yields a significantly improved determination coefficient, demonstrating the model’s enhanced ability to capture the complexity of the Spd parameter. The double-bootstrap analysis validates the statistical significance of all models, providing confidence intervals for each parameter. This approach emphasizes the importance of advanced 3D roughness descriptors for accurately analyzing surface textures in sandblasting processes, offering a reliable framework for surface characterization and industrial optimization
Enjeux et défis d’une recherche collaborative à l’école maternelle : (trans)formation des acteurs ?
No full textInternational audienceDans cette dernière communication, nous ferons une synthèse des communications puis nous ouvrirons les échanges pour ce qui concerne plus spécifiquement les choix méthodologiques faits et les transformations des acteurs. Nous réaliserons tout d’abord une synthèse des éléments conceptualisants et méthodologiques qui participent à ce que nous avons appelé une démarche de recherche « holistique » au sein d’un projet de recherche adoptant une épistémologie qualitive qui triangule un ensemble de données « objectives » en explicitant une approche intersubjective (Olivier de Sardan, 2008). Nous envisagerons ensuite la notion d’« approche plurielle » du français à des fins didactiques (recherche et formation). Pour finir, nous essaierons de mettre à jour les effets de transformation des acteurs au sein d’une recherche collaborative : nous reviendrons brièvement sur la notion de « (trans)formation » professionnelle pour les praticiens impliqués dans une recherche collaborative (Artois et al., 2022) et évoquerons plus explicitement une question qui nous semble nécessaire pour situer la diversité des épistémologies des recherches en didactique du français (Sénéchal, 2020) : quelles (trans)formations parmi les chercheurs impliqués dans une recherche collaborative ? En quoi les « conversations » partagées (Jaskula et Miguel Addisu, 2023 ; Payet, 2020) en sont-elles un ressort ? Nous envisageons cette communication comme une manière d’initier des échanges scientifiques avec les collègues présents, et nous appuierons sur les expériences partagées mais singulières des chercheurs participant au symposium.ARTOIS, P., MORIAU, J., WAGENER, M. (2022). Les usages de la recherche collaborative. Des défis et enjeux permanents. Les Politiques Sociales, 3-4(3), 4-13.JASKULA., M., MIGUEL-ADDISU V., (2023) Inclure des élèves nouvellement arrivés en France : transformations des acteurs au sein d'une recherche collaborative interprétative, Recherches en éducation. Dossier Les recherches en sciences de l'éducation et de la formation : places, rôles et vécus des acteurs, 51.OLIVIER DE SARDAN, J.-P. (2008). La rigueur du qualitatif. Les contraintes empiriques de l’interprétation socio-anthropologique. Academia-Bruylant.PAYET, J.-P. (2020). Les voix faibles. Pour une enquête par conversations. Dans COLLECTIF.B. (dir.), Parler de soi. Méthodes biographiques en sciences sociales, EHESS, 165-176.SENECHAL, K. (2020). La recherche de type collaboratif en didactique du français : vers une transformation de la discipline ? La Lettre de l'AIRDF, 67/1. Dossier. Les concepts dans la recherche en didactique du français. Les échos du 14e colloque de Lyon (27-28-29 aout 2019), 25-26.VINATIER, I., MORRISSETTE, J. (2015). Les recherches collaboratives : enjeux et perspectives. Carrefours de l'éducation, 39(1), 137-170
Enhanced solar-driven photocatalytic decomposition of ciprofloxacin antibiotic and Orange G dye using innovative g-C3N4/BiOCl/Ag2MoO4 nanocomposites: Experimental and Monte Carlo simulation studies
No full textInternational audienceThis study explores the production and application of a nanomaterial composed of g-C3N4, BiOCl, and Ag2MoO4 for the photocatalytic degradation of Orange G dye (OG) and Ciprofloxacin antibiotic (CIP). The synthesized nanocomposite photocatalyst (g-C3N4/BiOCl/Ag2MoO4), along with the individual photocatalysts (g-C3N4, BiOCl, and Ag2MoO4), were thoroughly characterized. This included analysing their crystallinity using XRD, structure with FTIR, morphology through SEM and TEM, and composition and valence states using EDX and XPS. The characterization examination approves the successful formation of g-C3N4/BiOCl/Ag2MoO4 nanoparticles with high crystallinity. The photocatalytic results indicated that the ternary nanocomposite is very effective at degrading pollutant molecules, achieving a 97 % reduction in Orange G in 60 min and a 90 % reduction in Ciprofloxacin in 100 min, facilitated by redox reactions powered by solar energy.Ultimately, the recyclable nature of the nanocomposite photocatalyst demonstrates its sustained photocatalytic efficacy over four cycles. Furthermore, through UV–vis diffuse reflectance spectroscopy (DRS) and active species capture, a proposed photocatalytic mechanism elucidates the enhanced performance of g-C3N4/BiOCl/Ag2MoO4. In simulation calculations, DFT was used to optimize the structures. Then, Monte Carlo simulations were applied to investigate the adsorption mechanism of the OG and CIP molecules on g-C3N4/BiOCl/Ag2MoO4 surface. As a result, the adsorption of OG on nanocomposite was higher than the adsorption of CIP on g-C3N4/BiOCl/Ag2MoO4 surface due to its high negative energy
The Effect of Spike Geometry on the Linear and Nonlinear Plasmonic Properties of Gold Nanourchins
No full textWet-chemistry synthesized Gold nanourchins (Au NUs), characterized by spiky morphologies with spherical cores, exhibit complex and geometry-dependent plasmonic properties distinct from those of symmetrical nanostructures. While plasmon hybridization and mode coupling in branched nanostructures have been broadly studied, the specific optical behavior of Au NUs-particularly regarding spike length distribution and ultrafast dynamics-remains underexplored. This study investigates the steady-state and transient absorption spectra of Au NUs with 50-80 nm cores and 5-20 nm spikes, revealing multiple resonance bands. Transient absorption spectroscopy at various excitation wavelengths confirmed the presence of distinct resonances. Electromagnetic simulations based on TEM tomography-inspired models identified two key extinction bands: a green-wavelength dark mode resonance and a red-nIR spike-induced resonance attributed to the lightning rod effect. Simulations further showed that short, uniformly distributed spikes (aspect ratio <= 1) weakly excite dark resonances, while longer spikes (aspect ratio > 1) induce hybridized longitudinal resonances and significant redshifts. Broad spike length distributions result in multiple coexisting resonances, aligning with experimental extinction spectra. A preliminary surface-enhanced Raman scattering study using 2-naphthalene thiol confirmed stronger enhancement for long-spiked Au NUs under 785 nm excitation, validating the field enhancement potential of the identified resonances