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Conservative Behavior of (87)Sr/(86)Sr Isotope Ratios from Soil to Olive Oil in Tunisia: A Tool for Geographical Traceability
No full text952306 EU Twinning European project TUNTWINThe measurement of (87)Sr/(86)Sr isotope ratios is a powerful tool for determining the geographical origin of food products, helping to fight against food fraud. This study evaluates the potential of Sr isotopic ratios for tracing the provenance of Tunisian olive oil. Soil, roots, leaves, olive oil, and pomace were analyzed from multiple orchards across Tunisia. A strong correlation (r = 0.99, p 0.05) demonstrated that extraction methods for the production of olive oil do not significantly alter the Sr isotopic signature. These findings establish Sr isotope analysis as a robust, processing-independent geographical tracer. By developing a Sr isotope database for Tunisian olive oil, this study provides a scientific framework for authentication, supporting regulatory efforts to prevent mislabeling and protect product integrity in global markets
Soybean protein wood adhesive with enhanced water resistance and low environmental impact through lignin-protein hybridization
No full textPré-dépôt HAL IPREM via X2HalInternational audienceSoybean meal, a by-product of soybean oil production, exhibits poor water resistance and is highly susceptible to mold, which are significant limitations hindering its large-scale industrial application. Inspired by the phenolic-amine chemistry, a fully bio-based soy protein wood adhesive was engineered to achieve excellent water resistance and environmental benefits. The process starts with oxidation of alkaline lignin using sodium periodate (NaIO4) to generate aldehyde/quinone functionality on the expense of some aliphatic/phenolic hydroxyl groups, for promoting its subsequent interaction with soy protein to yield target adhesive by Schiff-base formation and Michael addition reaction. Importantly, residual NaIO4 was meticulously removed to minimize its impact on the bonded substrate, the cross-linked network, and the environment, as it does not participate in the construction of the cross-linked architecture. The results showed that the dry and wet shear strength of SM-OL1.5 increased by 51.2 % and 80.8 % to 1.83 MPa and 0.94 MPa compared with SM adhesives, surpassing the China National Standard (GB/T 9846–2015, ≥0.7 MPa). Interestingly, the developed adhesive formulation exhibited mildew resistance, which can be attributed to the inherent feature of lignin to disrupt cell membranes and alter permeability, leading to cell lysis. Furthermore, the hybridized adhesive showcased minimal environmental impact, low volatile organic compound (VOC) emissions, and full compliance with global sustainability initiatives, making it a promising candidate for eco-friendly wood adhesive applications
Evaluation des impacts environnementaux d’un emballage vrac de gel douche par analyse de cycle de vie
No full textInternational audienceDans une logique d’économie circulaire, de plus en plus d’alternatives apparaissent dans le domaine des emballages, telles que des emballages réutilisables. Ces emballages permettent de diminuer la production de plastiques vierges mais aussi de déchets plastiques produits.Dans ce contexte, l’objectif de ces travaux est d’évaluer les impacts environnementaux par analyse de cycle de vie (ACV) d’un emballage de vente en vrac de gel douche et de les comparer à un flacon standard à usage unique.L’ACV a été réalisée selon les normes ISO 14040/14044, du berceau à la tombe, depuis l’extraction des matières premières jusqu’au traitement des déchets. L’unité fonctionnelle choisie est ‘contenir une utilisation de gel douche ; les deux scénarios comparés sont un flacon d’un litre à usage unique et un système de ‘Bag-In-Box’ (BIB) permettant aux consommateurs de remplir un flacon d’un litre réutilisable. La modélisation ACV a été réalisée sur le logiciel OpenLCA, les impacts environnementaux ont été évalués avec la méthode ‘Product Environmental Footprint’ (PEF), préconisée par la Commission européenne ; le score unique PEF a également été considéré. Les données d’inventaire ont été collectées auprès des acteurs de la filière (fabricant, distributeur) et complétées par des données de la littérature et de la base de données ecoinvent. Afin de prendre en compte l’utilisation de matières premières recyclées et le recyclage en fin de vie, la formule de l’Empreinte Circulaire (Circular Footprint Formula, CFF) a été choisie. Une analyse de sensibilité a été réalisée afin de comparer cette règle d’allocation avec la méthode Cut-Off et la méthode des impacts évités.Les résultats ont montré une diminution des impacts pour la majorité des impacts avec l’utilisation de l’emballage ‘vrac’ (excepté pour l’impact utilisation des terres). L’étape la plus impactante du scénario est l’étape du trajet en voiture réalisé par le consommateur pour acheter le gel douche. Des nouveaux scénarios incluant un déplacement en mobilité douce (à pieds, vélo) ont été modélisés. Avec ces nouveaux scénarios, la diminution sur l’ensemble des impacts et sur le score unique est beaucoup plus importante
Couplage sismo-électrique dynamique : des modèles fréquentiels aux modèles temporels
No full textThis thesis deals with the mathematical modelling of seismo-electric effects which occur in porous media comprised of charged fluid within an oppositely-charged solid matrix. As such, the medium is neutral at a macroscopic scale, but relative displacements between the solid and fluid induce electrical currents (displacement of charges). Seismic waves propagating in these media induce local fluid flow, hence charge displacements, leading to the creation of electromagnetic waves. Mathematically, this is modelled by Biot's equations of poro-elasticity coupled to Maxwell's equations. The coupling theory derived by S. Pride in 1994 is carried out in frequency domain, and the coupling quantities (coupling coefficient and dynamic permeability) depend on the frequency, in a manner that leads to difficulties in time domain. By interpreting these parameters as symbols of pseudo-differential operators that are global in time, it becomes clear that the model in time domain involves operators whose discretization will lead to very high computational cost. This explains why simulations carried out in time domain always involve a very low frequency model in which the frequency dependence of these parameters is masked.Two main developments are carried out. The first deals with the approximation of the frequency-dependent coupling operators, in order to obtain higher fidelity time domain seismo-electric equations, i.e. valid for a larger frequency range than the very low frequency approximations. This opens the perspective of using time domain equations in a laboratory scale. This thesis introduces several polynomial and rational approximation types and studies them numerically, leading to new time domain equations, which take into account the dynamic nature of the coupling. At low frequencies, local approximants such as Padé or Taylor (very low frequency) can be used. Global approximations --- Legendre and Chebyshev --- are used with high frequencies, or a wide frequency band. These approximations are tested numerically using analytical solutions to compute, as well as with a numerical code based on the hydridizable discontinuous Galerkin method in an HPC context.The second development deals with the mathematical analysis of Pride's equations in time domain with strong (bidirectional) coupling. Considering this bidirectional coupling introduces difficulties to show the well-posedness of the problem. As such, only one-way coupling has been considered to show well-posedness of the equations, that is electro-seismic coupling only. Two approaches are introduced in a low frequency approximation of the system. Firstly, an application of the Hille-Yosida Theorem to the full system. Secondly, we use a fixed-point technique, to show there exists a unique solution to the fully coupled system in a weak sense.Cette thèse s'intéresse à la modélisation mathématique des effets sismo-électriques qui se produisent dans des milieux poreux constitués de fluide chargé au sein d'une matrice solide de charge opposée. Ainsi, le milieu est neutre à l'échelle macroscopique, mais les déplacements relatifs entre le solide et le fluide induisent des courants électriques (déplacement de charges). Les ondes sismiques se propageant dans ces milieux induisent des écoulements locaux de fluide, donc des déplacements de charges, conduisant à la création d'ondes électromagnétiques. Mathématiquement, ceci est modélisé par les équations de poro-élasticité de Biot couplées aux équations de Maxwell. La théorie du couplage dérivée par S. Pride en 1994 est réalisée dans le domaine fréquentiel, et les paramètres de couplage (coefficient de couplage et perméabilité dynamique) dépendent de la fréquence, d'une manière qui induit de fortes difficultés en domaine temporel. En interprétant ces paramètres comme des symboles d'opérateurs pseudo-différentiels globaux en temps, on comprend que l'écriture du modèle dans le domaine temporel fait intervenir des opérateurs dont la discrétisation va générer de très lourds coûts de calcul. Cela explique pourquoi les simulations réalisées dans le domaine temporel impliquent toujours un modèle très basse fréquence dans lequel la dépendance en fréquence des paramètres est masquée. Deux développements principaux sont réalisés. Le premier s'intéresse à l'approximation des opérateurs de couplage dépendants de la fréquence, afin d'obtenir des équations sismo-électriques temporelles de plus grande fidélité, c'est-à-dire valable pour un régime de fréquence plus large que celui de la très basse fréquence. Cela ouvre ainsi la perspective d'utiliser des modèles en temps valide à l'échelle du laboratoire. Cette thèse introduit plusieurs types d'approximations polynomiales et rationnelles et les étudie numériquement, conduisant à de nouvelles équations temporelles, qui prennent en compte la nature dynamique du couplage. A basse fréquence, des approximants locaux tels que Padé ou Taylor (très basse fréquence) peuvent être utilisés. Des approximations globales --- de type Legendre et Chebyshev --- sont utilisées avec des fréquences élevées, ou une large bande de fréquence. Ces approximations sont testées numériquement en utilisant des solutions analytiques, ainsi qu'avec des solutions calculées avec le solveur basé sur une méthode de type Galerkine discontinu hybride (HDG) dans un contexte de calcul parallèle.Le deuxième développement concerne l'analyse mathématique du système d'équations de Pride dans le domaine temporel avec couplage fort (de Biot vers Marwell et de Maxwell vers Biot). Considérer ce couplage bidirectionnel introduit des difficultés pour prouver le caractère bien posé du problème. Ainsi, seules les équations couplées unidirectionnelles ont été démontrées comme étant bien posées, à savoir avec un couplage électro-sismique. Deux approches sont introduites. Premièrement, une application du théorème de Hille-Yosida au système entier en se plaçant dans une approximation basse fréquences du système. Deuxièmement, nous employons une technique de point fixe, afin de montrer qu'il existe une unique solution du système entièrement couplé au sens faible
Dual Weighted Residual-driven adaptive mesh refinement to enhance biomechanical simulations
No full textInternational audienceThis chapter describes how a posteriori error estimates targeting a user-defined quantity of interest, using the Dual Weighted Residual (DWR) technique, can be easily applied for biomechanical simulations in current engineering practice. The proposed method considers a very general setting that encompasses complex geometries, model non-linearities (hyperelasticity, fluid-structure interaction) and multi-goal oriented techniques. The developments are substantiated with some numerical tests
Synthèses sur l’état des populations, des pressions et des modalités de gestion des poissons migrateurs amphihalins en France : aloses, lamproies, saumon et truite de mer
No full textInternational audienceEn France, les poissons migrateurs amphihalins font l’objet d’une collecte de données le plus souvent décentralisée, généralement à l’échelle des comités de gestion des poissons migrateurs (COGEPOMI). Partant du constat qu’il n’existait pas de document de synthèse récent à l’échelle nationale sur l’état ces populations, le Pôle MIAME a entamé depuis une dizaine d’années la réalisation de synthèses bibliographiques. À l’heure actuelle, des synthèses ciblées ont été rédigées pour la lamproie marine, la lamproie fluviatile, la grande alose, l’alose feinte, le saumon atlantique et la truite de mer. Ces productions sont destinées à la fois aux gestionnaires locaux et nationaux, dans la mesure où elles permettent de comparer plus aisément l’état des populations entre les territoires
Uncovering diversity and abundance patterns of CO2-fixing microorganisms in peatlands
No full textInternational audienceMicroorganisms play a crucial role in the carbon (C) dynamics of peatlands — a major terrestrial C reservoir. Because of their role in C emissions, heterotrophic microorganisms have attracted much attention over the past decades. CO2-fixing microorganisms (CFMs) remained largely overlooked, while they could attenuate C emissions. Here, we use metabarcoding and digital droplet PCR to survey microorganisms that potentially fix CO2 in different peatlands. We demonstrate that CFMs are abundant and diverse in peatlands, with on average 1021 CFMs contributing up to 40% of the total bacterial abundance. Using a joint-species distribution model, we identified a core and a specific CFM microbiome, the latter being influenced by temperature and nutrients. Our findings highlight that ASV richness and community structure were direct drivers of CFM abundance, while environmental parameters were indirect drivers. These results provide the basis for a better understanding of the role of CFMs in peatland C cycle inputs
On the Competition Between Cross-Linking Agents and Anti-Oxidants in Radiation-Curable EVA-Blends of Technological Importance
No full textInternational audienceRadiation cross-linking is a well-established method to improve the performances and customize radiation-curable plastic-based insulating sheaths produced for various industrial sectors. In spite of their use for more than 50 years in the wire and cable industry, there is still a need for a deeper understanding and better control over the different stages of the fabrication process that include the selection of the plastics fillers and additives, the search for optimized composition, the determination of efficient conditions for blending, shaping and final radiation processing. The precise quantification by complementary analytical methods of the amount of extractable additives such as cross-linking agents and stabilizers was performed in plastic blends at various stages of their preparation and after electron beam treatments at doses up to 300 kGy. The competing effects of cross-linkers and stabilizers in EB-irradiated model EVA blends will be discussed more specifically. In particular, it was shown that: (i) stabilizers do not inhibit the curing process but have a retarding effect on the consumption of cross-linkers, (ii) type I crosslinkers (acrylates) are initially more reactive than those of type II (allyl derivatives) and (iii) the dose-dependance of the consumption of primary stabilizers (phenol-type) is stronger that of secondary anti-oxidants. The analytical data recorded from model formulations at various stages of their preparation and radiation curing can be correlated to the evolution of various thermophysical properties of practical interest, as well as to thermo-oxidative ageing
Development of High-Performance Biocomposites from Kenaf, Bagasse, Hemp, and Softwood: Effects of Fiber pH Modification and Adhesive Selection on Structural Properties Correlated with FTIR Analysis
No full textInternational audienceThis study aims to develop high-performance biocomposites for structural applications using kenaf, bagasse, hemp, and softwood fibers bonded with phenol-formaldehyde (PF) and phenol-urea-formaldehyde (PUF) adhesives, commonly used in particleboard manufacturing. A simple, low-cost fiber treatment was applied by adjusting the fiber pH to 11 and 13 using a 33% NaOH solution, following standard protocols to enhance fiber–adhesive interaction. The effects of alkaline treatment on the chemical structure of bagasse, kenaf, and hemp fibers were investigated using Fourier Transform Infrared Spectroscopy (FTIR) and correlated with composite mechanical performance. PF and PUF were applied at 13% (w/w), while polymeric diphenylmethane diisocyanate (pMDI) at 5% (w/w) served as a control for untreated fibers. The fabricated panels were evaluated for mechanical properties; modulus of elasticity (MOE), modulus of rupture (MOR), and internal bond strength (IB), and physical properties such as thickness swelling (TS) and water absorption (WA) after 24 h of immersion. FTIR analysis revealed that treatment at pH 11 increased the intensity of O–H, C–O–C, and C–O bands and led to the disappearance of the C=O band (~1700 cm−1) in all fibers. Bagasse treated at pH 11 showed the most significant spectral changes and the highest IB values with both PF and PUF adhesives, followed by kenaf at pH 13, exceeding EN 312:6 (2010) standards for heavy-duty load-bearing panels in dry conditions. The highest MOE and MOR values were achieved with kenaf at pH 11, meeting EN 312:4 (2010) requirements, followed by bagasse, while softwood and hemp performed less favorably. In terms of thickness swelling, bagasse consistently outperformed all other fibers across pH levels and adhesives, followed by Kenaf and Hemp, surpassing even pMDI-based composites. These results suggest that high-pH treatment enhances the reactivity of PF and PUF adhesives by increasing the nucleophilic character of phenolic rings during polymerization. The performance differences among fibers are also attributed to variations in the aspect ratio and intrinsic structural properties influencing fiber–adhesive interactions under alkaline conditions. Overall, kenaf and bagasse fibers emerge as promising, sustainable alternatives to industrial softwood particles for structural particleboard production. PF and PUF adhesives offer cost-effective and less toxic options compared to pMDI, supporting their use in eco-friendly panel manufacturing. FTIR spectroscopy proved to be a powerful method for identifying structural changes caused by alkaline treatment and provided valuable insights into the resulting mechanical and physical performance of the biocomposites
Enhanced weathering by multiscale destabilization of volcanic islands
No full textInternational audienceRéunion Island, a volcanic basaltic island situated in the Indian Ocean, is a well-known hotspot of weathering and erosion with particularly intense bedrock landslides. We estimated the contribution of large landslides to the dissolved load in the main rivers across Réunion Island using a mixing model, suggesting a significant enhancement of chemical weathering associated with landslides. Landslides can contribute to a decadal chemical weathering flux of up to 69 t/km2/yr, accounting for 82% of the weathering flux in one of Réunion's basins. Overall, chemical weathering in Réunion Island is predominantly driven by landslides, accounting for approximately 60% of the weathering flux. Notably, landslide-associated weathering can be promoted by intense precipitation events. We propose that large landslides on Réunion Island favor the exposure of both fresh and hydrothermal minerals to water, thereby promoting chemical weathering. Since these hydrothermal minerals were formed by fluid-rock reactions at an earlier stage of the volcano's evolution, our results highlight the cannibalistic nature of weathering in Réunion Island. As a consequence, river chemistry tends to overestimate present-day chemical weathering rates and associated consumption in Réunion Island. We expect this conclusion to hold true for other volcanic settings as well. Further work on the weathering of basaltic rocks based on river chemistry should therefore take into account the geomorphological evolution of volcanic edifices, the only truly integrated approach to assess the climatic impact of the emplacement of volcanic rocks on Earth