Portail des publications scientifiques IMT Mines Alès
Not a member yet
5198 research outputs found
Sort by
Phosphonation of Alginate–Polyethyleneimine Beads for the Enhanced Removal of Cs(I) and Sr(II) from Aqueous Solutions
No full textInternational audienceAlthough Cs(I) and Sr(II) are not strategic and hazardous metal ions, their recovery from aqueous solutions is of great concern for the nuclear industry. The objective of this work consists of designing a new sorbent for the simultaneous recovery of these metals with selectivity against other metals. The strategy is based on the functionalization of algal/polyethyleneimine hydrogel beads by phosphonation. The materials are characterized by textural, thermo-degradation, FTIR, elemental, titration, and SEM-EDX analyses to confirm the chemical modification. To evaluate the validity of this modification, the sorption of Cs(I) and Sr(II) is compared with pristine support under different operating conditions: the pH effect, kinetics, and isotherms are investigated in mono-component and binary solutions, before investigating the selectivity (against competitor metals) and the possibility to reuse the sorbent. The functionalized sorbent shows a preference for Sr(II), enhanced sorption capacities, a higher stability at recycling, and greater selectivity against alkali, alkaline-earth, and heavy metal ions. Finally, the sorption properties are compared for Cs(I) and Sr(II) removal in a complex solution (seawater sample). The combination of these results confirms the superiority of phosphonated sorbent over pristine support with promising performances to be further evaluated with effluents containing radionuclides
Time-Course of Changes in Multidimensional Fatigue and Functional Exercise Capacity and Their Associations during a Short Inpatient Pulmonary Rehabilitation Program
No full textInternational audienceThis study aimed to assess the time-course of changes in multidimensional fatigue and functional exercise capacity and their associations during an inpatient pulmonary rehabilitation (PR) program. Seventy COPD patients from three centres were enrolled for a four-week PR program and were evaluated before (T0) and at the end of each week (T1, T2, T3, and T4). Weekly change in multidimensional fatigue was assessed by the multidimensional inventory questionnaire (MFI-20) and functional exercise capacity by the 6-minute walking distance (6MWD). Reaction time (RT) and heart rate variability (HRV) were also assessed as complementary markers of fatigue. HRV did not change during the study (all p > 0.05). MFI-20 score and RT decreased during the first part of the program (p 0.05 compared with each preceding time). While 6MWD improved by almost 70% during the first part of the PR, it continued to increase, albeit at a greatly reduced pace, between T2 and T4 (p < 0.05). In parallel, a negative association was found between MFI-20 score and 6MWD at each evaluation time (r ranged from 0.43 to 0.71), with a significantly stronger T3 correlation compared with the other time periods (all p < 0.05). The strengthening of the association between fatigue and functional exercise capacity at T3, which occurred concomitantly with the slowdown of functional exercise capacity improvement, is consistent with a role for fatigue in the limitation of performance changes during PR. The limitation of fatigue during PR is thus an interesting aspect to improve the magnitude of performance changes
Dataset of open-source software developers labeled by their experience level in the project and their associated software metrics
No full textInternational audienceDevelopers are extracted from 17 open-source projects from GitHub. Projects are chosen that use the java programming language, the Spring framework and Maven/Gradle build tools. Along with these developers, 24 software engineering metrics are extracted for each of them. These metrics are either calculated by analyzing the source code or relative to project management metadata. Each of these developers then are manually searched for in professional social media such as LinkedIn or Twitter to be labeled with their experience level in their project. Outliers are statistically detected and manually re-assigned when needed. The resulting dataset contains 703 anonymized developers qualified by their 24 project-related software engineering metrics and labeled for their experience. It is suitable for empirical software engineering studies that need to connect developers’ level of experience to tangible software engineering metrics
An overview of approaches and methodologies for supporting smallholders: ICT tools, blockchain, business models, sustainability indicators, simulation models
No full textInternational audienceThe recent COVID-19 pandemic has highlighted all the weaknesses of manufacturing systems and supply chains. In thischallenging context, smallholders have faced several crises mainly related to the difficulty of finding manpower for harvestingactivities and the impossibility of distributing food, due to the forced closure of many distribution channels. The main consequenceswere lost sales and wasted food. With the aim of increasing the responsiveness of smallholders in the face of COVID-like crises,this paper provides an overview of methodologies and approaches currently available in the literature in terms of: ICT tools,blockchain-based solutions, business models, sustainability-oriented frameworks, simulation models. The analysis of the literatureprovides two main outputs: (1) a list of challenges to be faced in the coming years to improve the working conditions ofsmallholders, (2) the definition of future research developments, which mainly concern the design of an ICT platform, whichintegrates multiple technological aspects
Purpose in life and markers of immunity and inflammation: Testing pathways of episodic memory
No full textInternational audienceObjective: This prospective cohort study examines whether purpose in life is associated with markers of immunity and inflammation and tests these markers as mediators between purpose and episodic memory.Methods: Participants from the Venous Blood Study of the Health and Retirement Study reported on their purpose in life, had their blood assayed for markers of immunity and inflammation, and were administered an episodic memory task (N=8,999). Regression analyses tested the association between purpose and each marker. Prospective mediation analyses (N=6,092) tested whether these markers measured in 2016 were mediators between purpose measured in 2012/2014 and episodic memory measured in 2018.Results: Higher purpose in life was associated with lower neutrophil counts (β=−.08, p<.001), lower ratio of neutrophils/lymphocytes (β=−.05, p<.001), and lower systemic immune inflammation index (β=−.04, p<.001); purpose was unrelated to monocyte, platelet, and lymphocyte counts or the ratio of platelets/lymphocytes (all ns). Purpose was associated negatively with c-reactive protein (β=−.07, p<.001), Interleukin-6 (β=−.08, p<.001), Interleukin-10 (β=−.07, p<.001), Interleukin-1ra (β=−.08, p<.001), and soluble Tumor Necrosis Factor Receptor 1 (sTNFR1; β=−.10, p<.001); purpose was unrelated to Transforming Growth Factor beta 1. These associations were largely not moderated by age, sex, race, ethnicity, and education. Lower neutrophils, Interleukin-6, and sTNFR1 were associated prospectively with better episodic memory and mediated the association between purpose and episodic memory.Conclusion: Purpose in life is associated with markers of immunity and inflammation, some of which are one mechanism in the pathway between purpose and healthier episodic memory
Plasma Jet Technology to Improve the Hydrophobicity of Flax Fabrics
No full textInternational audienceFunctional textiles have become demanded in modern societies regarding their protective character (flame resistance, anti-bacterial…).Hydrophobic textiles are required in clothing and housing applications mainly as anti-stain materials.They are obtained conventionally using toxic elements like Fluor or chemical processes with waste (water waste, chemicals…). In this study, we investigated the hydrophobic properties of woven textile material based on flax and treated with Si grafting assisted by atmospheric plasma technology using Hexamethyldisiloxane, and HMDSO as Monomer. This treatment presents the advantages of being eco-friendly as a process (only electrical consumption of the plasma jet machine) and as chemicals (Si is non-toxic, no waste). We varied the concentration of grafted Si on the textile surface by changing machine parameters like HMDSO flow and exposition time of textile to plasma jet. Then we investigated its hydrophobicity and resistance to washing. Observations with Scanning Electronic Microscopy (SEM) show that the coating becomes thicker for higher concentration and more extended time exposition.Nevertheless, the coating is non-continuous and remains on the surface exposed to the jet without penetrating the fiber core. This coating significantly improves the textile substrate's hydrophobicity, evidenced by contact angle goniometry. The surface tension shows a spectacular decrease with a contact angle of 150°. The treated textiles have been washed to test the permanency of the treatment after 1, 2, and 3 washing cycles. Morphological and contact angle analyses showed a decrease in the quantity of Si deposition and the contact angle, evidencing a loss in the quantity of Si molecules grafted on the surface. However, the substrate was still hydrophobic with a contact angle of 130° versus 150° respectively for washed and non-washed material. This result proves that a thin film of Si is firmly grafted to the cellulosic material
Personality associations with lung function and dyspnea: Evidence from six studies
No full textInternational audienc
NANOCOMPOSITES CONDUCTEURS ELECTRIQUES A BASE DE 50PS/50PMMA ET GRAPHENE FONCTIONNALISE
No full textInternational audienceAvec l'essor de l'électrification des usages (mobilité, bâtiments, industrie), le développement de matériaux composites à matrices polymères et possédant des propriétés de conductivité électrique spécifique est devenu un enjeu majeur. Les nanocomposites contenant des nanoparticules de graphène apparaissent comme des matériaux prometteurs pour plusieurs applications1. Malgré les nombreux avantages qualitatifs du graphène en termes de propriétés électriques, mécaniques et thermiques, la dispersion dans les matrices polymères reste un défi. L'oxydation ou la fonctionnalisation du graphène peut améliorer la dispersion de ces nanoparticules mais les propriétés intrinsèques sont altérées. Un compromis doit être trouvé entre une bonne dispersion dans les matrices polymères et la préservation de la structure du graphène2. En fonctionnalisant du graphène afin de le disperser sélectivement à l'interface d'un mélange de polymères immiscibles, il est possible de réduire le seuil de percolation (Figure 1 ). Dans ce travail de thèse, une fonctionnalisation des feuillets de graphène avec un copolymère poly(methyl methacrylate-co-hydroxyl ethyl methacrylate, P(MMA-co-HEMA) (donnant une charge greffée notée GOxH-r-PMMA) a permis de localiser une partie des feuillets à l'interface d'un mélange co-continu PS/PMMA (GOxH-r-PMMA/PMMA)/PS)3. Cette localisation a permis d'atteindre une conductivité électrique de 10-3 S/cm ce qui rend le matériau obtenu éligible pour des applications en dissipation électrostatique
Vers une meilleure compréhension des mécanismes de rouissage en champ de tiges de chanvre Cannabis sativa L. dans le sud de la France : étude de la diversité des communautés bactériennes et fongiques en lien avec les caractéristiques intrinsèques des fibres.
No full textField retting of industrial hemp “Cannabis sativa L.” is a crucial step in the textile or bio-composite value chain. It is a natural process during which freshly harvested hemp stems are in contact with the soil for a few weeks. They are colonized by microorganisms that break down the “pectic cements” linking the fibres together, facilitating their mechanical extraction from the stem. Currently, retting is performed empirically by farmers, leading to fibres that do not uniformly possess the required characteristics to meet industrial demands. Moreover,considering the economic and climatic context, expanding hemp cultivation to other metropolitan areas (southern France) is presently seen as an alternative to meet the market demand for natural fibres and incorporate climate changes into the culture. Lastly, although they are key actors in this process, microbial communities remain poorly studied. Consequently, controlling retting is crucial. Therefore, this thesis aims to enhance understanding of the biological mechanisms of retting by adopting a two-level approach, by evaluating the morphological, physicochemical, and biochemical changes of hemp stems on the one hand, and characterizing the bacterial and fungal communities (diversity, structure, and activity) on the other. Relating these two components has been given particular attention.The degradation of lignocellulosic material was highlighted. Characterization of bacterial and fungal communities revealed an increase in diversity levels at the beginning of retting and enabled the identification of various bacterial and fungal phyla. The temporal dynamics of these communities revealed shifts in bacterial (Bacteroidota vs. Proteobacteria) and fungal (Ascomycota vs. Basidiomycota) populations simultaneous to a sequential degradation of plant cell wall components. An initial approach to controlling humidity was tested and paved the way for further reflection on the control of this parameter during retting. Lastly, the search for multifactorial interactions, incorporating both biotic and abiotic factors, revealed correlations that could result in better control of field retting.Le rouissage en champ des tiges de chanvre industriel « Cannabis Sativa L. » est une étape primordiale dans la chaîne de valeur textile ou biocomposites. Il s’agit d’un processus naturel pendant lequel les tiges fraîchement récoltées sont mises en contact avec le sol pendant quelques semaines. Elles sont colonisées par des microorganismes qui décomposent les « ciments pectiques » associant les fibres entre elles, facilitant leur extraction mécanique de la tige. Actuellement, le rouissage est réalisé de façon empirique par les agriculteurs, conduisant à des fibres qui ne possèdent pas, de manière homogène, les caractéristiques requises pour répondre aux exigences des industriels. De plus, en considérant le contexte économique et climatique, une extension de la zone de culture du chanvre à d’autres régions métropolitaines (sud de la France) se présente actuellement comme une alternative pour satisfaire la demande du marché des fibres naturelles et intégrer les changements climatiques dans la culture. Enfin, bien qu’étant les acteurs clés de ce processus, les communautés microbiennes restent mal connues. Par conséquent, la maîtrise du rouissage est cruciale. Cette thèse vise donc à améliorer la compréhension des mécanismes biologiques du rouissage en adoptant une approche à deux niveaux, par l’évaluation des changements morphologiques, physico-chimiques et biochimiques des tiges de chanvre d’une part, et la caractérisation des communautés bactérienne et fongique (diversité, structure et activité) d’autre part. La mise en relation de ces deux composantes a fait l’objet d’une attention particulière.La dégradation de la matière lignocellulosique a été mise en évidence. La caractérisation des communautés bactérienne et fongique a révélé une augmentation du niveau de diversité au début du rouissage et a permis d’identifier différents phyla bactériens et fongiques. La dynamique temporelle de ces communautés a mis en évidence des modifications des niveaux d’abondance de populations bactériennes (Bacteroidota vs. Proteobacteria) et fongiques (Ascomycota vs. Basidiomycota) simultanément à une dégradation séquentielle des composants de la paroi cellulaire végétale. Une première approche du contrôle de l’humidité a été testée et ouvre la voie à une réflexion plus poussée sur le contrôle de ce paramètre pendant le rouissage. Enfin, la recherche d’interactions multifactorielles intégrant à la fois des facteurs biotiques et abiotiques a révélé des corrélations qui pourraient se traduire, sur le terrain, par une meilleure maîtrise du rouissage
Poly-condensation of N-(2-acetamido)-2-aminoethanesulfonic acid with formaldehyde for the synthesis of a highly efficient sorbent for Cs(I)
No full textInternational audienceA new sorbent (ACES-F micro-particles) is readily synthesized by the one-pot reaction of N-(2-acetamido)-2-aminoethanesulfonic acid with formaldehyde (poly-condensation reaction). The mesoporous sorbent is characterized by BET analysis (SBET: ≈6 m2 g−1), SEM-EDX (N: ≈7–8 % and S: 5 %), FTIR spectroscopy (identification of amine, sulfonic groups and their interactions with metal ions), TGA, elemental analysis, and titration (pHPZC: ≈5.7). The study of pH effect on Cs(I) shows an optimum close to 8 (with intermediary optimum at pH 4, associated with different reactive groups). The micron-size sorbent shows fast sorption (equilibrium in 60 min) and the pseudo-first order rate equation fits the kinetic profile. The sorption isotherm reaches up to 1.99 mmol Cs g−1; the Langmuir equation models isotherm profiles. The sorption decreases with increasing temperature; sorption is exothermic. Cesium uptake is affected by the presence of NaCl; however, even in large excess of salt (i.e., 4 M) sorption remains relatively high (loss <60 %). Selectivity is confirmed by the remarkable preference of the sorbent for Cs against alkali and other competitor metal ions, especially at pHeq ≈7. Metal desorption is highly effective using 0.3 M HNO3 solutions: complete desorption occurs in 30 min. The sorbent can be recycled for at least five cycles (losses <3 %). The interest of ACES-F for cesium recovery from seawater is confirmed by the study of Cs(I) sorption (and other major elements) from Vietnam and Egypt samples. The safety of the sorbent for aqueous bodies is evaluated by the cytotoxicity of the sorbent (limited against normal cells but highly reactive for cancerous cells); while the sorbent shows interesting antimicrobial properties for Gram+, Gram- and pathogenic yeast