Portail des publications scientifiques IMT Mines Alès
Not a member yet
5198 research outputs found
Sort by
Dual strategy for enhanced and selective uranium sorption by ion-imprinting functionalized chitosan – Fast and efficient recovery from processed acid ore leachate
No full textInternational audienceUranium recovery from complex effluents requires the combination of different processes including metal sorption from low-concentration solutions containing several competitor metal ions. The design of efficient sorbents (BTC/CH(s), 2-(benzo[d]thiazol-2-yl)-N-carbamoyl acetamide grafted chitosan) that combine both high sorption capacity and high selectivity was achieved by adopting a dual strategy: (a) selecting efficient functional groups (amine, amide, thioester, and hydroxyl groups, in BTC/CH sorbents), and (b) adapting the arrangement of reactive groups appropriately to fit the specific shape of the complexes (ion-imprinting IP vs. non-ion-imprinted NIP materials). This dual strategy was applied to design a chitosan-based sorbent with high sorption capacity (≈1.5 mmol U g−1), fast uptake (equilibrium: 15–20 min), remarkable stability (limited loss of performances after 10 reuse cycles), and strong selectivity (tested on both equimolar multi-component solutions and pre-treated acid leachate), at moderately acidic pH (i.e., 4). Ion-templating strategy effectively improved selectivity by 5–10-folds. Uptake kinetics was fitted by the pseudo-first order rate equation, while the sorption isotherms were finely simulated by the Temkin equation. The sorption was exothermic, spontaneous, and the ion-templating allowed reaching more organized structure. The sorbent was highly selective against base metals, alkali and alkali-earth metals, but less efficient for the separation from thorium or rare-earth elements. The sorbent was successfully used for the recovery of residual uranyl from acidic leachates pre-treated with resins (Amberlite IRA-400 and DOWEX 50, for the recovery of U and rare-earth elements, respectively) and precipitation step (removal of Al(III)/Fe(III) at pH 4). The sorbents were characterized by elemental analysis, FTIR and XPS spectroscopy for analyzing the chemical structure of the materials and identifying their interactions with U(VI). Textural properties and pHpzc values were analyzed for supporting sorption behaviors
Kinetic analysis of TCPP emission from fireproofed upholstered furniture under realistic indoor conditions
No full textPre-print : https://papers.ssrn.com/sol3/papers.cfm?abstract_id=4925260.International audienceBetter understanding the characteristics and mechanisms governing the indoor emissions of organophosphorus flame-retardants is important to more accurately estimate the human exposure to these compounds and develop risk management strategies that protect human health. This study provides an analysis of short- and long-term trends in Tris(chloropropyl)phosphate (TCPP) emissions from furniture. It is based on the monitoring over a period of almost one year of TCPP concentrations in indoor air and at the surface of a source material (upholstered furniture made of polyurethane (PU) foam containing TCPP) in two rooms for office use. The emission rate was estimated at 8 µg.m-2.h-1 in average with no decline trend observed after about one year's emission. The released mass of TCPP over one year represented about 0.2 % of the initial content of TCPP in the material (2 % w/w). The source material/air partition coefficient (Kma) and its dependence on temperature appear to be the key parameters which control the emission rate. Kma was estimated at 8 × 107 for a temperature of 23 °C. The temperature dependence of Kma was addressed using the Clausius–Clapeyron relationship and the enthalpy of partitioning between the source material and air, ΔHma (previously estimated at 91 kJ mol−1). This study led to the development of a model providing predictions on the long-term trend in TCPP emission from the source material. The simulations showed that the emission should persist over extended periods (several years) with the same intensity level. This characteristic increases the risks associated with inhalation exposure to TCPP
Influence de l’illusion de mouvement induite par vibration tendineuse sur l’activité des régions cérébrales sensorimotrices chez des sujets sains âgés et des patients AVC en phase aiguë
No full textInternational audienceIntroduction :La vibration tendineuse (VT) active les fuseaux neuromusculaires afférents, générant une activité des régions cérébrales sensorimotrices à l’origine des illusions de mouvement (IM). Cependant, l’IM peut être amplifiée (IM+) ou atténuée (IM-) en l’absence ou présence de vision. L’objectif de cette étude était de tester l’hypothèse selon laquelle l’IM+ induite par VT majore l’activité corticale sensorimotrice/frontopariétale mesurée par spectroscopie dans le proche infrarouge fonctionnelle (fNIRS) chez des sujets sains et des patients AVC en phase aigüe.Méthode :Cette étude transversale a inclus 30 sujets sains âgés (63±8 ans) et 21 patients AVC (68±10 ans, AVC<14 jours) qui ont bénéficié de VT sur le tendon distal du triceps brachial droit/gauche et sur le bras parétique gauche pour les patients AVC. Les VT ont été appliquées avec ou sans vision du bras, résultant en conditions VT avec IM+ et IM-. Chaque condition comprenait 6 blocs de VT (15s) suivies de repos (25-35s). L'hémodynamique cérébrale (variations [HbO] et [HbR]) a été mesurée en continu par fNIRS (46 canaux longs-4 canaux courts, Brite MKII/MKIII) dans les régions sensorimotrices et frontopariétales au cours de chaque condition.Résultats :Chez les sujets âgés, des réponses hémodynamiques majoritairement controlatérales à la VT dans les régions sensorimotrices et frontopariétales ont été observées dans les conditions VT avec IM+ et IM-. Ces activations étaient plus étendues au sein de ces régions dans la condition VT avec IM+. Le groupe AVC ne présentait pas de réponse hémodynamique significative quelle que soit la condition.Discussion :Ces résultats suggèrent que la VT avec IM induit une réponse cérébrale observable chez les sujets sains mais pas chez les patients AVC. Ce phénomène pourrait être expliqué par une perturbation du fonctionnement hémodynamique cérébral global induite par l’AVC en phase aiguë. Des études ultérieures comprenant des données cliniques et des images structurelles cérébrales sont nécessaires pour expliquer ces observations
Sustainable Flame-Retardant Flax Fabrics by Engineered Layer-by-Layer Surface Functionalization with Phytic Acid and Polyethylenimine
No full textInternational audienceNew generation of mission-oriented fabrics meets advanced requirements; such as electrical conductivity, flame retardancy, and anti-bacterial properties. However, sustainability concerns still are on-demand in fabrication of multi-functional fabrics. In this work, we used a bio-based phosphorus molecule (phytic acid, PA) to reinforce flax fabrics against flame via layer-by-layer consecutive surface modification. First, the flax fabric was treated with PA. Then, polyethylenimine (PEI) was localized above it to create negative charges, and finally PA was deposited as top-layer. Fourier-transform infrared (FTIR) spectroscopy, thermogravimetric analysis (TGA), scanning electron microscopy (SEM), energy dispersive X-ray spectrometry (EDX), and inductively-coupled plasma atomic emission spectrometry (ICP-AES) proved successful chemical treatment. Pyrolysis-combustion flow calorimetry (PCFC) showed significant drop by about 77% in the peak of heat release rate (pHRR) from 215 W/g for untreated to 50 W/g for treated flax fabric. Likewise, the total heat release (THR) decreased by more than three times from 11 to 3.2 kJ/g. Mechanical behavior of the treated flax fabric was completely different from untreated flax fabrics, changing from almost highly-strengthened behavior with short elongation at break to a rubber-like behavior with significantly higher elongation at break. Surface friction resistance was also improved, such that the abrasion resistance of the modified fabrics increased up to 30,000 rub cycles without rupture
Standardised operating procedures for recommendations in the field of physical and rehabilitation medicine
No full textInternational audienceBackground: There is an outstanding increased demand for recommendations in the rehabilitation field. Over 600 recommendation articles have been published in the last decade, primarily by groups of authors based on unclear criteria and only a few by learned societies based on standardized methods.Objectives: In 2007, the French Society of Physical and Rehabilitation Medicine (SOFMER) published a methodology to establish recommendations in physical and rehabilitation medicine (PRM). This framework, which served to publish 22 sets of management recommendations, must be reworked to meet new international methods for elaborating recommendations. Therefore, our objectives were: 1) to elaborate an updated methodology to enhance the dissemination and implementation of SOFMER-endorsed recommendations, and 2) to standardize and report in sufficient detail the successive steps from the elaboration of these recommendations to the evaluation of their impact and provide supporting tools to guide developers.Methods: At the SOFMER's request, a steering committee assembled, consisting of 7 PRM senior physicians with experience in elaborating, disseminating, implementing and/or evaluating recommendations in the field of PRM. They conducted a non-systematic literature review to identify methodologies and standardized operating procedures previously published by scientific societies in France and overseas. Available information regarding strategies for elaboration, dissemination, implementation and evaluation of the recommendations, scientific valorization and business models was retrieved. Participants in previous recommendations were also interviewed regardless of their field.Results: We identified 4 common key steps: preparation, elaboration, valorization and evaluation, usually scheduled according to an 18- to 24-month timetable. We divided these 4 steps into 9 sub-steps, each of which was standardized and described in detail. The steering committee also elaborated a specific editorial process for publishing recommendations.Conclusions: This novel SOFMER methodology was designed to draw up high-level recommendations for the field of PRM and, more generally, for rehabilitation practices, facilitating their implementation. Standardization of operating procedures should provide guidance to authors to achieve replicable and high-quality recommendations
Évaluation de la fiabilité des architectures basées sur les Transformers pour la segmentation du cancer de la prostate : une analyse rigoureuse et exhaustive
No full textInternational audienceMalgré la popularité croissante des Transformers dans la segmentation d'images médicales, leur application au cancer de la prostate cliniquement significatif (csPCa) a été peu étudiée. L'analyse des changements de domaine et l'évaluation de l'incertitude, essentielles pour une mise en œuvre sûre des systèmes d'aide au diagnostic (CAD), ont reçu peu d'attention. En imagerie médicale, le changement de domaine désigne les différences entre les données d'entraînement et d'évaluation, dues aux variations des équipements, protocoles, populations de patients et bruits d'acquisition. Bien que les modèles récents améliorent les performances dans leur domaine d'entraînement, la robustesse et l'incertitude hors domaine restent peu explorées, soulevant des doutes sur leur fiabilité.Notre étude aborde le csPCa à plusieurs niveaux (voxel, lésion et image) en comparant des modèles traditionnels comme U-Net et des modèles basés sur des Transformers. Nous nous concentrons sur quatre points clés : robustesse, calibration, données hors domaine (OOD) et détection des erreurs de classification (MD). Les résultats montrent que les modèles basés sur des Transformers offrent une robustesse accrue aux niveaux image et lésion, tant dans le domaine qu'hors domaine. Cependant, cette amélioration reste limitée au niveau voxel, où les réseaux de neurones convolutifs (CNN) obtiennent de meilleurs résultats sur plusieurs métriques. En ce qui concerne l'incertitude, les Transformers hybrides et les encodeurs se distinguent par de meilleures performances, bien que cela dépende des tâches, notamment la détection des erreurs ou des données hors domaine
Cardiopulmonary Fitness and Physical Activity Among Children and Adolescents With Inherited Cardiac Disease
No full textInternational audienceImportance: Historical restrictions on children with inherited cardiac arrhythmia or cardiomyopathy have been implemented to mitigate the potential risk of sudden death, but these limitations can be detrimental to overall health and cardiopulmonary fitness.Objectives: To evaluate cardiopulmonary fitness and physical activity among children with inherited cardiac disease and identify the factors associated with maximum oxygen uptake (V̇o2max) in this population.Design, Setting, and Participants: This cross-sectional, multicenter, prospective controlled study was conducted in 7 tertiary care expert centers for inherited cardiac disease in France from February 1, 2021, to June 20, 2023, with a 2-week follow-up. Participants included 100 children and adolescents aged 6 to 17 years with inherited cardiac arrhythmia or cardiomyopathy who were compared with 107 sex- and age-matched controls.Main Outcomes and Measures: Maximum oxygen uptake was assessed using cardiopulmonary exercise testing, and results were expressed using pediatric reference z score values. The main determinants of V̇o2max included clinical (New York Heart Association [NYHA] functional class, treatment, echocardiographic, and electrocardiogram variables), functional (cardiopulmonary exercise test parameters), sociodemographic (sex, schooling, and parents’ education), and behavioral (physical activity and motivation) characteristics.Results A total of 100 patients (mean [SD] age, 12.7 [3.1] years; 52 boys [52.0%]) and 107 controls (mean [SD] age, 11.7 [3.3] years; 54 boys [50.5%]) were included. The V̇o2max was lower in patients than controls, expressed as z scores (mean [SD] score, −1.49 [1.48] vs −0.16 [0.97]; P < .001) or raw values (mean [SD] value, 32.2 [7.9] vs 40.2 [8.5] mL/kg/min; P < .001). Moderate to vigorous physical activity levels were lower in patients than in controls (mean [SD] level, 42.0 [23.6] vs 48.2 [20.4] min/d; P = .009). The final multivariable model explained 80% of the V̇o2max by integrating clinical (lower NYHA functional class, absence of ventricular dilatation, and absence of implantable cardioverter-defibrillator), functional (higher forced vital capacity and ventilatory anaerobic threshold), sociodemographic (male sex, normal progression of schooling, and higher maternal educational level), and behavioral (higher self-reported physical activity and motivation toward physical activity) parameters.Conclusions and Relevance: This cross-sectional study suggests that levels of cardiopulmonary fitness and physical activity were lower in children and adolescents with inherited cardiac disease than in healthy controls, even after adjusting for use of β-blockers and using modern pediatric reference models. Assessing cardiopulmonary fitness among children with inherited cardiac disease can contribute to engaging in a shared decision-making process for sports participation and preventive interventions, such as early cardiac rehabilitation programs
Comparison between different processing routes to disperse cellulose nanocrystals into polyvinyl alcohol
No full textInternational audienceCellulose nanocrystals (CNC) exhibit a low density, a high specific surface area and a highYoung’s modulus. Due to these advantages, CNC are expected to become nanomaterials witha great potential as sustainable and high-performance fillers for the development of polymerbasedmaterials with high thermo-mechanical, optical and barrier properties. Nowadays,they are mainly used in paper manufacturing, packaging, membranes and bioengineering.Hence, their performances when dispersed in thermoplastic (TP) polymers are promising.Eventhough dispersing CNC nanoparticles into polymers with scalable processing is a keychallenge. In the literature, several processing methods have been used to dispersed CNC(or CNF) into TP polymers: solvent-casting, melt processes (such as microcompounder,internal mixer or extruder) and other more innovative processes such as chilled extrusionor wet compounding. More recently, the Kyoto process has been developed to dispersecellulose nanofibers (CNF) into polymers directly from pre-functionalized wood pulp withan in-situ extrusion. In this work, different processing routes based on solvent-casting, meltmixing and wet compounding, were compared to achieve stiffer nanocomposites based onthermoplastic polyvinyl alcohol (PVA) and unmodified CNC. The objective is to identifythe key processing parameters necessary to obtain a good dispersion of CNC that can bestimproves the mechanical properties of the final composite. The impact of the processingmethod on the CNC dispersion in PVA is discussed, in particular by means of rheological,mechanical and microstructural analyses of PVA/CNC composites
POSS in intumescent flame-retardant systems to improve fire behaviour of virgin and recycled high density polyethylene
No full textInternational audienceThis study aims to compare the properties of two recycled and a virgin High-Density Polyethylene (HDPE), flame retarded with intumescent formulations based on Ammonium Polyphosphate (APP), Polyamide 6 (PA6), and Polyhedral Oligomeric Silsesquioxane (POSS). The microstructure and mechanical properties of the blends were studied using scanning electron microscopy (SEM) and tensile tests. Cone calorimetry was used for flammability assessment at different irradiances. Thermal degradation was investigated using Pyrolysis Combustion Flow Calorimetry (PCFC) and Thermogravimetric analysis (TGA). X-ray diffraction (XRD) and SEM were used to characterize the cone calorimeter residues. It was shown that the addition of the intumescent flame retardant system (IFR) led to an improvement in terms of fire behaviour with a higher decrease on pHRR and an increase on the amount of residue for recycled HDPE. The addition of POSS nanoparticles improved fire performance by creating more cohesive and expanded residues, especially in formulations with recycled HDPE from milk bottles. Recycled HDPE formulations exhibited comparable or even slightly better mechanical properties than virgin HDPE. The best combination of mechanical and fire performance was achieved with 1wt% of POSS in both virgin and recycled formulations. However, adding more than 2wt% of POSS negatively impacted tensile properties and fire behaviour, due to the inability to disperse POSS agglomerates
New insights on physicochemical features and toxicological outcome provided from incineration of nanocomposites
No full textInternational audienceThis study focuses on research in the area of "nanomaterials in waste" and shows the difficulty of providing quantitative data on nanomaterials in different wastes. As highlighted in the ECHA report (November 2021) and although substantial progress have been made in the characterization and measurement of nanomaterials, some challenges remain, particularly the characterization of nanomaterials in complex media. Therefore, work to improve the detection, characterization, and quantification of nanomaterials should be continued to complete the database with different types of nanowaste mixtures. The dominant end-of-life scenario for nanocomposites is the incineration. The environmental by-products impact on the soil and air have been considered from the point of view of nanoparticles partitioning and the potential toxicological synergistic effects. A specific management of nanocomposites end-of-life should be implemented as recommended by the Organization for Economic Co-operation and Development (OECD) in order to limit nanoparticles dissemination by landfilling and particularly in incineration facilities where their presence is significantly increasing. The aim of our study was to expand the current knowledge of the partition of nanowaste, mainly in case of nanocomposites mixture, and the potential synergetic or antagonistic impact of potential hazardous nanowastes on the toxicological profile. Incineration products of ethylene-vinyl acetate copolymer (EVA) and polydimethylsiloxane (PDMS) nanocomposites containing both silica and precipitated calcium carbonate, corresponding to cable sheaths compositions, were investigated in this study, using a lab-scale incineration process. Soot and residue composition were analysed using various relevant experimental techniques in order to assess the presence of initial nanoparticles. In vitro toxicological assessments were carried out and have shown that only pro-inflammatory responses seem to be affected by the presence of nanoparticles. SiO2 nanoparticles appear to have a major impact on toxicity whatever the partitioning in soot or residue. Conversely, CaCO3 as expected does not impact the nanowaste toxicity and does not seem able to mitigate the SiO2 toxicity