HAL Portal UPPA (University of Pau and the Pays de l'Adour)
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A semi-Lagrangian method for the direct numerical simulation of crystallization and precipitation at the pore scale
No full textInternational audienceThis article introduces a new efficient particle method for the numerical simulation of crystallization and precipitation at the pore scale of real rock geometries extracted by X-Ray tomography. It is based on the coupling between superficial velocity models of porous media, Lagrangian description of chemistry using Transition-State-Theory, involving underlying grids. Its ability to successfully compute dissolution process has been established in the past, and is presently generalized to precipitation and crystallization by means of adsorption modeling. Numerical simulations of mineral CO 2 trapping are provided, showing evidence of clogging/non-clogging regimes, and one of the main results is the introduction of a new non-dimensional number needed for this characterization
The Effect of Alginate/Hyaluronic Acid Proportion on Semi-Interpenetrating Hydrogel Properties for Articular Cartilage Tissue Engineering
No full textInternational audienceOne of the emergent regenerative treatments for the restoration of the articular cartilage is tissue engineering (TE), in which hydrogels can functionally imitate the extracellular matrix (ECM) of the native tissue and create an optimal microenvironment for the restoration of the defective tissue. Hyaluronic acid (HA) is known for its potential in the field of TE as a regenerative material for many tissues. It is one of the major components of the articular cartilage ECM contributing to cell proliferation and migration. HA is the only non-sulphated glycosaminoglycan (GAG). However, herein, we use a HA presenting a high amount of sulphated glycosaminoglycans (sGAGs), altering the intrinsic properties of the material particularly in terms of biological response. Alginate (Alg) is another polysaccharide widely used in TE that allows stiff and stable hydrogels to be obtained when crosslinked with CaCl2. Taking the benefit of the favourable characteristics of each biomaterial, semi-interpenetrating (semi-IPN) hydrogels had been developed by the combination of both materials, in which alginate is gelled, and HA remains uncrosslinked within the hydrogel. Varying the concentration of alginate and HA, the final rheological, viscoelastic, and mechanical properties of the hydrogel can be tailored, always seeking a trade-off between biological and physico-mechanical properties. All developed semi-IPN hydrogels have great potential for biomedical applications
Les instances nationales dans le domaine de l’utilisation des animaux à des fins scientifiques
No full textInternational audienceIn France, the regulation of the use of animals for scientific purposes is mainly overseen by two ministries: the Ministry in charge of Higher Education and Research (MESR) and the Ministry in charge of Agriculture (MASAF). They work closely together to develop and implement, along with other ministries and bodies, the regulatory provisions designed to ensure that the use of animals for scientific purposes is carried out in compliance with the ethical principles and legislation in force, in this case European Directive 2010/63/EU transposed into the Rural Code in the form of Decree 2013- 118 and its Orders of February 2013. The two ministries rely on the opinions of the National Commission for the Protection of Animals Used for Scientific Purposes (known as the ‘CNEA’) and the National Committee for Ethical Reflection on Animal Experimentation (CNREEA), which reports to the CNEA.En France, la réglementation concernant l’utilisation des animaux à des fins scientifiques est principalement supervisée par deux ministères : le ministère en charge de l’Enseignement Supérieur et de la Recherche (MESR) et le ministère en charge de l’Agriculture (MASAF). Ils travaillent en étroite collaboration pour élaborer et mettre en œuvre, avec d’autres ministères et organismes, les dispositions réglementaires visant à garantir que l’utilisation des animaux à des fins scientifiques est réalisée dans le respect des principes éthiques et de la législation en vigueur, en l’occurrence la directive européenne 2010/63/EU transposée dans le Code rural sous forme du décret 2013- 118 et ses arrêtés de février 2013. Les deux ministères s’appuient sur les avis de la Commission nationale pour la protection des animaux utilisés à des fins scientifiques (dite « CNEA ») et du Comité national de réflexion éthique sur l’expérimentation animale (CNREEA) qui est placé auprès de la CNEA
C'est aux frontières que l'on perçoit souvent la singularité de l'Europe
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Associations de défense de l'environnement : moteurs de la justice environnementale face au juge administratif
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Robots de téléprésence dans un contexte éducationnel
No full textNational audienceLe cadre de notre démonstration est l'utilisation de robots de téléprésence dans un contexte éducationnel, et plus particulièrement à destination d'élèves absents longuement de leur établissement scolaire pour raisons de santé. Nous proposons aux personnes présentes à CNRIUT de découvrir les conclusions de trois ans d'observation de l'utilisation de ces robots, à travers une démonstration de la manipulation du robot, et un questionnaire interactif portant sur les conclusions de ces observations. Les participants pourront ainsi mieux comprendre l'impact du robot à la fois sur l'institution, ses personnels et son organisation, ainsi que sur les apprentissages reçus par les élèves bénéficiaires
Structure–property relationship of atomically-precise silver acetylide clusters in the electroreduction of CO 2
No full textInternational audienceThe synthesis of a library of silver acetylide cluster catalysts for the electroreduction of CO2 is described. The methodology relies on a one-step reaction between terminal alkynes and an aqueous silver ammoniacal solution, producing a library of clusters isolated via simple filtration. Their catalytic properties in the CO2 electroreduction reaction were thoroughly assessed, focussing on faradaic efficiency, overpotential, turnover frequency and their structural features characterised via powder XRD, XPS and electrochemical methods. It was found that the chemical structure of the ligand had a strong impact on the overall crystallinity of the cluster, and a correlation between crystallinity, overpotential and selectivity was established. Our study points to the importance of the number of Ag(0) active sites formed under reducing conditions, which are directly linked to the ligand chemical structure, while the overpotential and selectivity are rather dictated by the degree of order (crystallinity) of the whole cluster
SalmoGlob – Un nouveau modèle pour l’évaluation des stocks de saumon atlantique à l’échelle de l’Atlantique Nord
No full textInternational audienceÉvaluer l'état des populations de poissons sauvages est essentiel pour guider une gestion efficace dans un contexte de fortes pressions sur la ressource. Dans le cadre du projet SalmoGlob, les chercheurs ont développé un modèle innovant pour évaluer les stocks de saumon atlantique dans l’Atlantique Nord. Ce modèle intègre des données depuis 1971, permettant d’analyser la dynamique des populations à différentes échelles et stades de vie. Adopté par le Conseil international pour l’exploration de la Mer en 2024, il améliore significativement la qualité des évaluations scientifiques et des scénarios de gestion face aux changements globaux
Time-Resolved Dynamics of Mercury Uptake, Methylmercury Production, and Export by Pseudodesulfovibrio hydrargyri BerOc1 at Different Mercury Concentrations
No full textInternational audienceMethylmercury (MeHg) is highly toxic and is mainly produced in anoxic environments by certain microorganisms. Net MeHg production involves a series of separate cellular processes: the uptake of inorganic divalent Hg (Hg(II)) by the cell, intracellular enzymatic Hg(II) methylation, and the release of MeHg into the extracellular medium, as well as MeHg demethylation. As a biological process, saturation at the cellular level can be anticipated at all stages of the Hg transformation. The aim of this study was to investigate the kinetics of Hg(II) methylation and MeHg demethylation over a 24-h period in the model sulfate-reducing strain Pseudodesulfovibrio hydrargyri BerOc1, across a range of Hg(II) concentrations from 0.03 to 3.15 μM. The distribution of Hg(II) and MeHg over 24 h within three cellular fractions (extracellular, adsorbed to the cells, and intracellular) was determined to estimate Hg uptake and export. With increasing Hg(II) concentrations, we observed (i) an increase in the accumulated intracellular Hg(II), (ii) a reduction in the methylation rate, and (iii) an increase in MeHg associated with the cells after a short Hg(II) exposure time (<1 h). Our study suggests that the saturation of MeHg production is likely not driven by Hg(II) uptake but rather by Hg(II) intracellular speciation, Hg(II) methylation by HgcAB proteins, and/or MeHg export. These results are essential to better predict and understand the parameters influencing MeHg production within more complex environments, such as anoxic sediments and soils
