HAL Université de Savoie
Not a member yet
59053 research outputs found
Sort by
Determinants of return to performance and recovery time in elite alpine skiers after ACL surgery
No full textInternational audienceAbstract Purpose Return to performance (RTPerf) after anterior cruciate ligament (ACL) surgery remains difficult to predict in elite alpine skiers, as general criteria may not fully apply. This study aimed to identify determinants and the time needed to achieve RTPerf at the same competitive level. Methods A prospective cohort of 71 elite alpine skiers (mean age: 23.6 ± 5.2 years; height: 173.0 ± 7.8 cm; weight: 72.0 ± 12.1 kg) who underwent ACL surgery was analysed. Demographic and contextual variables, including sex, age, world ranking and type of injury, were collected. Isokinetic knee muscle strength was assessed six months postsurgery. RTPerf (YES/NO) and time to return were evaluated 2 years postoperatively using the International Ski and Snowboard Federation points system. Associations with categorical and quantitative variables were assessed using χ 2 and t ‐ or Mann–Whitney U tests. Variables with p < 0.2 were included in multivariable logistic regression. Predictors of return time were analysed using Cox regression and receiving operating characteristic (ROC) curves. Statistical significance was set at p < 0.05. Results Seventy‐nine percent of skiers returned to preinjury performance within 2 years. Primary ACL injury (vs. revision) (odds ratio [OR]: 6.6; 95% confidence interval [CI]: 1.85–23.6; p = 0.004) and isolated injury (vs. complex) (OR: 5.35; 95% CI: 1.39–20.48; p = 0.014) were significant predictors. Average return time was 348 ± 51.6 days. Greater relative knee extensor strength was associated with earlier return. Limb symmetry in knee extension at 60°/s predicted return within 1 year, while the hamstring‐to‐quadriceps functional ratio at 90°/s predicted later return (area under the curve [AUC]: 0.78; p < 0.01). Conclusions Primary and isolated ACL injuries were linked to higher RTPerf rates, while greater knee extensor isokinetic strength was associated with shorter time to RTPerf in elite alpine skiers. Level of Evidence Level II
Développement d'un Procédé de Séparation des Métaux Précieux issus des Déchets de Cartes Électroniques par Voie Électrochimique en Milieu Solvant Eutectique Profond
No full textInternational audienc
Modelling endurance in free-ranging animals using tracking collars: insights from domestic hunting dogs
No full textInternational audienceEndurance is crucial for animal survival yet remains poorly studied in free-ranging animals. An animal's endurance time decreases as a hyperbolic function of increasing exercise intensity, called the speed–duration relationship. This relationship allows for defining critical speed, the endurance threshold separating efforts where metabolic homeostasis is achievable from efforts where fatigue accumulates drastically. Using tracking collars on domestic dogs during hunting sessions, we demonstrated the ability to determine the speed–duration relationship and its parameters: the initial speed (Si), critical speed (Sc) and distance reserve (DAC,max). This new method exhibits good repeatability across sessions and bypasses conventional laboratory assessment, allowing the characterisation of physical capacities in natura. Our approach provides the unique possibility to study when, where and how long free-ranging animals experience fatigue and helps uncover how environmental factors affect their energy expenditure
Propeline, a green electrolyte for precious metals electrometallurgy?
No full textInternational audience“Deep eutectic solvents” (DES), of low reactivity and volatility, are often considered as green alternative to conventional electrolytes for electrometallurgy of precious metals (electrowinning, electrorefining, electroplating, electropolishing...). In particular, the DES named Ethaline (choline chloride-ethylene glycol mixture) has been widely used because of its acceptable viscosity and the presence of substantial chloride concentration leading to a high solubility of numerous metallic compounds [1]. However, if choline chloride (ChCl) can be considered as a “green” reactant, ethylene glycol (EG) is known to be harmful to men and animals in case of repeated exposure or inhalation periods. Comparable DES with a lower toxic nature than Ethaline can be obtained by replacing EG by other glycols e.g. propylene glycol (PG) [2], widely used in cosmetics and pharmacology, with costs comparable to those of EG; the resulting DES is named Propeline. We will present here the potential of this less known DES for the electrometallurgy of silver and gold.The first part of this work deals with the determination of Propeline density, viscosity, conductivity and electrochemical stability, which are properties of interest for electrochemical processes [3]. The speciation of dissolved metals was then determined by use of cross-linked analysis, namely UV-vis, and EXAFS/XANES spectroscopic techniques. Electrochemical systems were then thoroughly studied by electrochemical methods. In particular, diffusion coefficients of the solvated metal species were determined by electrochemical transient and stationary techniques, using a protocol specifically developed for these viscous media [4]. The influence of electrodeposition conditions (deposition mode, current/potential values, direct or pulsed deposition) on deposit morphology was then evaluated. Anodic and cathodic faradic efficiencies were determined after thorough development of analytical procedures dedicated to elemental analysis e.g. ICP-EOS in DES. Finally, to evaluate the viability of the process, the re-usability of the electrolyte was studied by GC-MS analysis after repeated runs of electrolysis. The influence of water content on DES properties and on the stability of the metallic species was also thoroughly investigated. As an illustration, the applicability of the process to Ag and Au recovery from WEEE (Waste from Electrical and Electronic Equipment), which is currently under study with the french industrial partner Terra Nova Developpement, will be presented with its technological locks/issues and potentialities.References:[1] Abbott, A. P.; Frisch, G.; Gurman, S. J.; Hillman, A. R.; Hartley, J.; Holyoak, F.; Ryder, K. S. Chem. Commun. 2011,47 (36), 10031–10033. https://doi.org/10.1039/C1CC13616J[2] LaKind, J. S.; McKenna, E. A.; Hubner, R. P.; Tardiff, R. G. Crit. Rev. Toxicol. 1999, 29 (4), 331–365.https://doi.org/10.1080/10408449991349230[3] Calogera Bertoloni, Vitalys Mba Ekomo, Benoît Villemejeanne, Charly Lemoine, Romain Duwald, EmmanuelBilly, Hakima Mendil-Jakani, Sophie Legeai, Comptes Rendus. Chimie, 2024, 27 (S4), pp.1-12.https://doi.org/10.5802/crchim.297[4] Calogera Bertoloni, Sophie Legeai, Stéphanie Michel , Eric Meux, François Lapicque, Environmental Science:Advances, 2024, 3 (6), pp.875-884. https://doi.org/10.1039/D4VA00042
Enhanced performance of reversible solid oxide cells using high-surface-area nanostructured thin-film oxygen electrodes
No full textInternational audienceReversible solid oxide cells (rSOCs) are highly efficient electrochemical energy conversion devices which provide a promising pathway to green energy challenges. An essential factor for achieving high performance and enabling their commercialization is the selection of the oxygen electrode material, as it significantly impacts polarization resistance at intermediate-to-low temperatures (< 700 ◦C). La2NiO4+δ (L2NO4) stands out as a promising material due to its mixed ionic and electronic conductivity, high oxygen exchange activity and low activation energy. In this work, L2NO4 nanostructured thin films were first optimized in symmetrical cells reaching polarization resistance values as low as 0.07 Ω cm2 at 600 ◦C. The films were then integrated into state-of-the-art commercial button cells and tested in both fuel cell (SOFC) and electrolysis (SOEC) modes revealingextremely high performance, with a power density of 1.2 and 1.3 W cm 2 at 0.7 V at 670 and 725 ◦C, respec-tively, in SOFC mode, and a current density of 1.2 A cm 2 at 1.3 V and 670 ◦C in SOEC mode. The superiorefficiency compared to commercial cells emphasizes the nano-engineering strategy for enhancing performance while minimizing the use of critical raw materials. This is achieved by employing approximately 10–15 times less oxygen electrode material (g cm 2), a crucial factor for the sustainable development of these devices
Mas Aguilhon Saint-Marcel-d’Ardèche Retour sur la question gravettienne dans la vallée du Rhône
No full textInternational audienc
Differential decay rate of with the LHCb Upgrade I experiment
No full textInternational audienceThe normalised decay rate of is measured as a function of the lepton helicity angle using a data sample corresponding to an integrated luminosity of collected during October 2024 with the upgraded (Upgrade I) LHCb detector. This angular distribution can be parameterised by two coefficients, the forward-backward asymmetry, , and the flatness parameter, , whose values are constrained by conservation of angular momentum. These coefficients are measured both integrated and differentially across various kinematic and detector-response variables, and the results are found to be in good agreement with expectations. These measurements show that the detector response of the LHCb Upgrade I experiment is understood to the precision required to reliably extract the angular coefficients associated with rare and transitions, which are particularly sensitive to physics beyond the Standard Model
From the Virgo interferometer calibration to the bias and uncertainty of the h(t) detector strain during the O4 run
No full textInternational audienceSince the first gravitational wave detection in 2015, ground-based interferometer sensitivities have significantly improved, requiring highly precise calibration to ensure accurate reconstruction of the h(t) strain signal. In this talk we will outline the Virgo interferometer calibration steps performed in preparation of the O4b run started in April 2024. We will first describe the Photon Calibrator power devices intercalibration allowing for a 0.48% precision on mirror displacement. Before explaining how the Photon Calibrator is used to calibrate every Virgo mirror actuators. We will also discuss the monitoring of the h(t) strain reconstruction during the run showing that, on the 10 Hz to 2 kHz band, the reconstructed strain achieves a precision of 2% in modulus and 30 mrad in phase. Special emphasis will be given on the newly developed frequency-dependent bias and uncertainty computation method and the resulting online unbiasing of the h(t) strain
Membranes for fuel cells and electrolyzers: state of art and issues
No full textInternational audienceMembranes are often considered the core component of fuel cells and electrolyzers, facilitating the transfer of ions—such as protons in Proton Exchange Membranes (PEM) or hydroxides in Hydroxide Exchange Membranes (HEM)—between electrodes while preventing the crossover of reactant gases. The efficiency of these electrochemical systems is largely dependent on the Membrane Electrode Assembly (MEA). An effective membrane must endure the challenging operating conditions of these systems, necessitating high chemical and mechanical stability, as well as thermal robustness across a range of operating temperatures.Traditional PEMs, which operate below 100°C, are typically made from perfluorosulfonic acid (PFSA). The hydrophobic, perfluorinated backbone of PFSA provides mechanical strength and chemical stability, while the hydrophilic sulfonated side chains enhance water absorption, forming hydrated clusters. However, these membranes have several drawbacks, including high costs and environmental concerns, prompting researchers to explore alternative materials.In contrast, Hydroxide Exchange Membranes (HEMs) have garnered significant attention due to their potential for high performance and low cost in water electrolysis and fuel cell applications. Recent advancements have addressed the primary challenges of low ionic conductivity and insufficient stability in HEMs. Innovations in materials science have led to the development of new materials with finely tuned ion transport channels and molecular designs that enhance stability under operating conditions.This presentation will provide a comprehensive overview of the latest advancements in HEMs, focusing on the mechanisms, influencing factors, and strategies to improve ionic conductivity and stability. Special attention will be given to the importance and regulation of ion transport channels, including channel size, orientation, and the development of membranes with intrinsic channels
