Synthesis, Structural Investigation, and Energetic Performance Study of ZIF-25

International audienceThe synthesis of ZIF-25 was successfully optimized by using acetic acid as a modulator agent, yielding a highly crystalline material. The product exhibits significant porosity, thermal stability up to 300 °C, and hydrophobicity, making it ideal for use in lyophobic heterogeneous systems (LHSs). Notably, the crystal structure of ZIF-25 was refined for the first time using the Rietveld method and fully reported in space group Pm-3m. Energetic performance evaluation in intrusion−extrusion experi- ments shows that the “ZIF-25−water” system dissipates mechanical energy with adsorbed and released energies of ∼15−19 and ∼10 J g−1, respectively. These features make it an LHS with shock- absorber characteristics. The study highlights that the energetic behavior of ZIFs is topology-dependent, with RHO-type ZIFs such as ZIF-25 and ZIF-71 showing shock-absorber properties, while SOD-type ZIFs (like ZIF-8) exhibit spring-like behavior. Post-experiment characterizations, performed by X-ray diffraction, nitrogen adsorption at 77 K, and scanning electron microscopy, indicate moderate and pressure-dependent degradation when the material is subjected to pressurized water intrusion

A la croisée des chemins : Etude des jugements sociaux des célébrités et des influenceurs en tant qu'endosseurs de marque

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Effet d'un entraînement en résistance combiné à de la vibration sur la composition corporelle et la balance énergétique - Résultats de l'étude d'alitement prolongé MNX

International audiencePurposeHigh volume exercise is crucial in preventing spaceflight-induced muscle atrophy but can induce reductions in body mass (BM) and fat mass (FM), due to a mismatch between energy intake (EI) and total energy expenditure (TEE). This randomized cross-over trial investigated whether short-duration resistive-vibration exercise (RVE) prevents muscle loss without inducing negative energy balance (EB) during a medium-duration bedrest (IDRCB n°2012-A00337-36).MethodsTwelve healthy young males underwent a 21-day bedrest with RVE or without (CNT) in a randomized cross-over trial, each trial being separated by at least 120 days. Subjects could leave unfinished the meals designed to match their estimated TEE. TEE was assessed using doubly labeled water and EB from dual X-ray absorptiometry-generated body composition changes.ResultsCompared to strict bedrest, RVE limited by 25% the bedrest-induced loss in BM (P<0.07) and lean BM (P=0.12), without reaching significance, and partially lessened the decline in overall muscle function and aerobic capacity. RVE reduced resting metabolic rate decrease (P=0.03) without increasing activity energy expenditure and TEE. Both groups adjusted their EI to match the reductions in TEE, resulting in equilibrated EB.ConclusionRVE may offer some benefits in mitigating muscle mass and function decline under microgravity conditions, without affecting EB and FM

Photoelectrocatalytic response of tris(2,2′-bipyridyl)ruthenium(II)-modified mesoporous silica film on ITO electrode with methyl viologen quencher and EDTA donor

International audienceIn the present paper, we investigate the photoelectrochemical behaviour of a tris(bipyridine) derivative (denoted [Ru(bpy)2(bpy')] 2+ ) covalently immobilized in the nanochannels of a vertically aligned mesoporous silica film (VMSF) generated by electrochemically assisted self-assembly (EASA) onto a transparent indium-tin oxide (ITO) electrode, in solutions containing a quencher (methyl viologen, MV 2+ ) and a model substrate partner (ethylenediaminetetraacetate, EDTA). The optimal film loading was first determined according to its solid-state photophysical properties. Then, the electrochemically accessible [Ru(bpy)2(bpy')] 2+ moieties were exploited in the presence of the MV 2+ quencher alone in solution (aerated medium) to demonstrate the possible electrochemical regeneration of the photocatalyst immobilized in VMSF on ITO. This was achieved on the basis of experiments carried out by hydrodynamic amperometry at constant potential under successive sequential illumination (at 400 nm) and dark periods. Finally, the functionalized film was applied to the photoelectrocatalytic oxidation of EDTA in an oxygen-free solution containing also MV 2+ species, thanks to the effective electrochemical regeneration of the quencher, as also evidenced by photocurrent measurements as a function of time with successive switching of light from 'off' to 'on' and vice versa. Such photoelectrocatalytic transformation of EDTA is possible at a much lower potential (-0.1 V) than that observed for its direct electrocatalytic oxidation by the same [Ru(bpy)2(bpy')] 2+ -functionalized film operating without light (+1.2 V).</div

Fast hybrid FNN-GPR modeling for state of health estimation in Lithium-ion cells using early charge data: addressing performance variability

International audienceAccurate State of Health (SOH) estimation is essential for optimizing lithium-ion battery performance, especially in second-life applications. This paper introduces a fast SOH estimation method using the first 10 seconds of charge voltage data, followed by polynomial regression to extract features for AI algorithms. A hybrid model combining Feed-Forward Neural Networks (FNN) and Gaussian Process Regression (GPR) is proposed. This model was more accurate in detecting the SOH using just 10 seconds of charge voltage data, compared to other references that use approximately 6000 seconds of data. Using the Oxford Battery Dataset, we show that FNN excels in early-cycle estimations, while GPR performs better over full cycles. After detecting and excluding poorly performing cells, the combined model achieves superior accuracy, highlighting its potential for second-life battery applications and cell balancing strategies

« Le SMCB se devait d'être le Maître d'Oeuvre de ces études multidisciplinaires ». Radiological Control and Environnemental Studies of the French Nuclear Tests in the 1960s

International audienceWhen the French decided to test their nuclear devices in Polynesia, knowledge of the South Pacific environment was scarce, even though it was a key factor in controlling radioactivity and protecting health. The Service Mixte de Contrôle Biologique, created in 1964, was dedicated to studying the effects of the tests on the environment and in particular on non-human living organisms. The presentation will focus on the process developed by the SMCB to gather information on the local environment and monitor contamination of human bodies through the trophic chain. At the heart of this study, civilian scientists under contract to the Direction des Centres d'Expérimentations Nucléaires (DirCEN) contributed their knowledge of the Pacific environment to enlighten the military, doctors and atomic scientists and help them design a process for assessing the direct and indirect impact of detonations on the environment. How did these scientists interact with those in charge of the nuclear tests? How did their tasks and personal motivations fit into the nuclear framework of the DirCEN? We will focus on two moments in this collaboration to explore the agentivity of these contractors and their influence on the creation of an environmental monitoring system: firstly, the two-year period preceding the tests, when the biologists and the SMCB carried out the first environmental studies and chose the means of monitoring radioactivity in the natural world, and secondly, the aftermath of the first test campaign. A comparison between the initial framework and its actual application shows some divergences and reveals the variety of motivations underlying environmental monitoring. It also shows that despite these differences, scientists took advantage of such an opportunity to advance science with real agency, while the DirCEN took advantage of the precise and technical knowledge of these scientists to strengthen its control over the trophic chain

Enhancing surface area of HNO₃-activated digestate-derived biochar for methylene blue adsorption: RSM-CCD optimization, DFT-MD calculations, and mechanistic study

International audienceThis study highlights the potential of anaerobically treated sewage sludge, a by-product of anaerobic digestion (AD) produced in large quantities by wastewater treatment plants (WWTPs), which is further thermally activated to yield biochar. This biochar serves as a template for HNO3 modification, enabling efficient pollutant remediation. Herein, we investigated the removal efficiency of methylene blue (MB) using modified biochars under different HNO3&gt; concentrations. The BC-HN9 exhibited the best MB sorption performance and was selected for further investigations, including characterization, evaluation of adsorption parameters, and investigations of kinetic and isotherm models. It was determined that chemical and physical interactions contribute to MB sorption, with the maximum adsorption capacity of 176.05 mg·g−1. Additionally, thermodynamic investigations confirmed that the process is endothermic and occurs spontaneously. The adsorption mechanism of MB was analyzed using DFT, radial distribution function (RDF), Monte Carlo (MC) and molecular dynamics (MD) calculations in combination with advanced techniques. The findings indicate that adsorption is facilitated by electrostatic interactions, pore filling, H-bonding, as well as n-π and π-π interactions. This method demonstrates a scalable approach to producing activated biochars, providing both an effective pathway for fabricating high-value carbon materials and a practical means of mitigating environmental pollution associated with biomass waste

"Préface" dans Aragon, Mes caravanes et autres poèmes

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Machinability analysis of UD-GFRP composites in edge trimming with diamond-coated burr tools at various fiber orientations

International audienceMachining operations that are usually required during the manufacturing process of fiber-reinforced polymers (FRPs) are likely to generate numerous specific defects on the machined parts. Cutting tools with specific geometries, such as burr tools with many pyramidal teeth, help to reduce this type of defect. Previous studies in milling with this kind of tool focused mainly on multidirectional (MD) FRP composites. However, it is well known that fiber orientation is a critical parameter in FRP machining. Accordingly, this paper presents a machinability analysis of unidirectional (UD) FRP composites in edge trimming at various fiber orientations, for the specific case of burr tools. Edge trimming experiments are conducted using glass fiber reinforced polymer (GFRP) composites and diamond-coated burr tools. For each machining test, cutting forces, machined surface temperature and surface quality are quantified, as well as defects on external plies, which are characterized with a device specifically developed for this purpose. The results demonstrate that all the parameters are affected greatly by fiber orientation. The maximum temperature rise and the resultant force generally move in the same direction. The surface irregularities, and the maximum rise in temperature, move globally in opposite directions. Uncut fibers on the lower face of the workpiece are related to axial forces and may be facilitated by high temperatures. Moreover, the effect of fiber orientation on cutting forces in the workpiece plane, machined surface temperature and surface quality is analogous to previous literature on orthogonal cutting