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Deep crustal deformation driven by reaction-induced weakening
No full textInternational audienceDeep crustal shear zones, fundamental to the dynamics of terrestrial plate tectonics, exhibit complex processes of initiation and evolution that are yet to be comprehensively quantified across both long and short temporal scales. Conventionally, thermo-mechanical models posit that crustal rock behaviour is dominated by monomineralic aggregates undergoing processes like intracrystalline plastic deformation by dislocation creep. However, high-pressure and temperature conditions in crustal rocks involve minerals with extremely strong mechanical properties, challenging strain localization theories. Drawing on deformation experiments performed at eclogite-facies conditions, our research reveals that strain is efficiently localized through dissolution-precipitation creep, operating at notably lower stresses than dislocation creep. Strain accommodation and mass transfer are episodically accelerated by local transient fluid flow resulting from grain boundary movements, fracturing and densification reactions. Our results illuminate the interconnected thermo-hydro-mechanical-chemical processes underpinning crustal shear zone development, regardless of the plastic strength of mineral phases. We advocate that the inception and progression of subduction plate interfaces are predominantly steered by local transient changes of rheology beyond the seismogenic zone. Such changes are rooted in the chemical disequilibrium and fluid concentration of the slab materials, including sediments and mafic to ultramafic rocks.</div
PCM-LLM: Bridging Non-Verbal Consciousness Modeling and Language Processing to Make Intelligent Social Virtual Agents Closer to Human Beings
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The polarimetric response of the Nançay Radio Telescope and its impact on precision pulsar timing
No full textInternational audienceContext. Precision pulsar timing and studies of pulsar radio emission properties require accurate polarimetric calibration of the radio observations since incorrect calibration can distort profiles and introduce noise in time of arrival (TOA) data. In a previous article we presented a new method for calibrating pulsar observations conducted with the Nançay decimetric Radio Telescope (NRT), which significantly improved NRT polarimetric measurements and pulsar timing quality for data taken after this method was developed, in November 2019.Aims. Results from the above-mentioned study hinted at a dependence of the polarimetric response of the NRT on the observed direction. We therefore investigated this potential dependence, since unaccounted variations in the instrumental response could degrade polarimetric measurements. Additionally, our aim was to develop a method for properly calibrating NRT pulsar observations conducted before November 2019.Methods. We conducted three series of observations of bright pulsars over wide declination ranges, in a special observation mode in which the feed horn rotates by ~180° degrees across the observation; this enabled us to determine the full polarimetric response of the NRT while modeling potential variations in calibration parameters with hour angle and declination. In addition, we developed a method that uses the measurement equation template matching (METM) technique to improve the calibration of pre-November 2019 data.Results. From the analysis of the series of observations of bright pulsars with horn rotation, we found that the polarimetric response of the NRT does not appear to vary with hour angle or declination. On the other hand, the new METM-based calibration method appears to significantly improve the calibration of pre-November 2019 data. By analyzing NRT data on a selection of millisecond pulsars, we found that the new polarimetric profiles are more homogeneous, they generally have higher signal-to-noise ratios, and found that the TOA data for these MSPs are more accurate and contain lower levels of noise, especially when combining the new calibration method with the matrix template matching (MTM) method for extracting TOAs from pulsar observations
Simulation à l'échelle mésoscopique d'un renfort tissé en fibres de lin
No full textToday, in a context of sustainable development and the lightening of structures, the integration of composite parts based on flax fibers is increasingly popular with manufacturers. One of the categories of processes used to manufacture these parts is Liquid Composite Moulding (LCM). This type of process consists of a step of reinforcement preforming in a dry state in a mold and then a step of injection of the resin. Nevertheless, the preforming of complex parts from woven flax fiber reinforcements in these processes is a major obstacle to the widespread use of this material. During the preforming of the parts, the reinforcements undergo various stresses that induce structural modifications to both the reinforcement and its properties, the impact of which is currently poorly controlled, especially in the case of natural fibers. In order to provide an answer to this problem and in a process control dynamic, it is planned to set up a predictive simulation of a woven flax fiber reinforcement. Woven reinforcements have different study scales, each of which has advantages and disadvantages in terms of the nature of the information they offer and the associated calculation time. In order to have both global and local results of the reinforcement deformation mechanisms and a reasonable computation time, the simulations carried out in this study are at the so-called mesoscopic scale, i.e. the scale of the yarn and their interlacing. This simulation therefore requires reliable and coherent geometry, an elementary reinforcement cell and a behavior law representative of the behavior of flax yarn. Knowing that there are different types of reinforcement architectures and different types of yarns, the present study focuses on a 2x2 twill type reinforcement woven with roving-type yarn, i.e. almost parallel fiber yarns. The study builds on previous work carried out at this scale for reinforcements woven with synthetic fiber roving. The installation of an elementary reinforcement cell is ensured without interpenetration of the yarnss and with an efficient mesh. The behavior law of the equivalent homogeneous material of flax fiber yarns is one of the challenges of this study. Indeed, the natural and discontinuous character of the fibers implies both a geometric variability of the yarns made from these fibers and a variability in the mechanical properties inherited from the fibrous assembly. The objective of the present study is therefore to determine, with the help of the analysis of experimental tests on rovings, the very specific behavior of these flax rovings during different loads in order to feed the behavioral law necessary for the simulations.Aujourd'hui dans un contexte de développement durable et d'allègement des structures, l'intégration de pièces composites à base de fibres de lin est de plus en plus plébiscitée par les industriels. L'une des catégories de procédés permettant la fabrication de ces pièces est le Liquid Composite Moulding (LCM). Ce type de procédé consiste en une étape de préformage d'un renfort à l'état sec dans un moule puis à une étape d'injection de la résine. Néanmoins, le préformage de pièces complexes à partir de renforts tissés en fibres de lin dans ces procédés constituent un frein majeur à la généralisation de l'utilisation de ce matériau. Lors du préformage des pièces, les renforts subissent différentes sollicitations qui induisent des modifications à la fois structurelles du renfort et de ses propriétés dont l'impact est à ce jour assez peu maitrisé, notamment dans le cas des fibres naturelles. Afin d'apporter une réponse à cette problématique et dans une dynamique de maîtrise des procédés, il est envisagé de mettre en place une simulation à but prédictif d'un renfort tissé en fibres de lin. Les renforts tissés disposent de différentes échelles d'étude dont chacune présente des avantages et inconvénients sur la nature des informations qu'elles proposent et sur le temps de calcul associé. Pour disposer à la fois de résultats globaux et locaux des mécanismes de déformation du renfort et d'un temps de calcul raisonnable, les simulations réalisées dans cette étude sont à l'échelle dite mésoscopique, c'est-à-dire l'échelle des mèches et de leur entrelacement. Cette simulation nécessite donc de disposer d'une géométrie fiable et cohérente d'une cellule élémentaire de renfort et d'une loi de comportement représentative du comportement des mèches de lin. Sachant qu'il existe différents types d'architectures de renforts et différents types de mèches, la présente étude s'intéresse à un renfort de type sergé 2x2 tissé avec des mèches de type roving, c'est-à-dire des mèches de fibres quasiment parallèles.L'étude s'appuie sur de précédents travaux menés à cette échelle pour des renforts tissés avec des roving de fibres synthétiques. La mise en place d'une cellule élémentaire de renfort est assurée sans interpénétration des mèches et avec un maillage efficace. La loi de comportement du matériau homogène équivalent des mèches de fibres de lin représente l'un des enjeux de cette étude. En effet, le caractère naturel et discontinu des fibres implique à la fois une variabilité géométrique des mèches fabriquées à partir de ces fibres et une variabilité des propriétés mécaniques hérité de l'assemblage fibreux. L'objectif de la présente étude est donc de déterminer, à l'aide de l'analyse d'essais expérimentaux sur rovings, le comportement très spécifique de ces rovings de lin lors de différentes sollicitations afin d'alimenter la loi de comportement nécessaire aux simulations
Fused K-operators and the -Onsager algebra
No full textInternational audienceWe study universal solutions to reflection equations with a spectral parameter, so-called K-operators, within a general framework of universal K-matrices - an extended version of the approach introduced by Appel-Vlaar. Here, the input data is a quasi-triangular Hopf algebra , its comodule algebra and a pair of consistent twists. In our setting, the universal K-matrix is an element of satisfying certain axioms, and we mostly consider the case is the quantum loop algebra for , and is the alternating central extension of the -Onsager algebra. Considering tensor products of evaluation representations of in "non-semisimple" cases, the new set of axioms allows us to introduce and study fused K-operators of spin-; in particular, to prove that for all they satisfy the spectral-parameter dependent reflection equation. We provide their explicit expression in terms of elements of the algebra for small values of spin-. The precise relation between the fused K-operators of spin- and evaluations of a universal K-matrix for is conjectured based on supporting evidences. Independently, we study K-operator solutions of the twisted intertwining relations associated with the comodule algebra , and expand them in the Poincaré-Birkhoff-Witt basis. With a reasonably general ansatz, we found a unique solution for first few values of which agrees with the fused K-operators, as expected. We conjecture that in general such solutions are uniquely determined and match with the expressions of the fused K-operators
Impacts of summertime photochemical aging on the physicochemical properties of aerosols in a Paris suburban forest region
No full textInternational audienceOrganic Aerosols (OA), which significantly affect the climate system and human health, often contain a substantial fraction of atmospherically processed species known as Oxygenated Organic Aerosol (OOA). However, the formation pathways and evolution of OOA remain poorly understood. To address this need, an experiment was conducted in a suburban forest in the Paris region to systematically study the evolution of OOA and their optical properties. Our results show that the photochemical processes drove significant increases in total submicron particle mass concentrations in the forest site, primarily via the production of OOA derived from both biogenic and anthropogenic emissions. Air mass origin critically influenced Particulate Matter (PM) pollution levels and photochemical activity: under elevated pollution and intense solar radiation during continental air mass-dominated periods, rapid formation of More-Oxidized OOA (MO-OOA) occurred. This MO-OOA dominated Brown Carbon (BrC) contributions, enhancing short-wavelength light absorption by 35 % on average after a relative ~24-hour photochemical aging process. Conversely, periods dominated by clean maritime air masses featured humid, low‑radiation conditions that yielded reduced pollution levels and an increased proportion of nitrogen‑enriched, Less‑Oxidized OOA (LO‑OOA). Suppressed photochemical activity during the clean maritime period limited MO-OOA production, resulting in a lower overall oxidation state of OA. These findings underscore the dual role of photochemistry in shaping aerosol optical properties and climate impacts, highlighting the necessity of accounting for air mass dynamics and oxidation pathways in suburban forest regions
Approches formelles pour les composants et outils système
No full textNational audienceCet exposé présente des approches formelles d’une part pour la vérification de composants système et d’autre part pour la formalisation d’outils système. Dans la première partie, on considère des programmes C, tandis que dans la seconde, on considère des langages de configuration.Frama-C est un framework pour l’analyse et la vérification de programmes C. Il propose une collection d’analyses sous forme de greffons qui peuvent collaborer, parmi lesquels EVA pour l’analyse statique par interprétation abstraite, WP pour la vérification déductive, E-ACSL pour la vérification dynamique, RTE pour la génération d’annotation pour assurer l’absence de Runtime Error ou encore MetACSL pour la vérification de propriétés de haut-niveau. Nous abordons les fonctionnalités de Frama-C via des cas d’études de composants systèmes avec un focus sur la vérification déductive, mais aussi ses limites et quelques recherches en cours pour les repousser, notamment dans le cadre du projet ANR CoMeMoV.Les grands systèmes logiciels distribués sont désormais omniprésents. Les systèmes à base de composants offrent un moyen pratique de structurer de grands systèmes, en particulier les systèmes déployés dans le Cloud, au cœur ou à la périphérie du réseau. Les opérations DevOps, fournies par divers outils, qui incluent la configuration et la reconfiguration de système, sont nécessaires pour gérer divers types de scénarios tels que la tolérance aux pannes, l'évolutivité, les mises à jour logicielles ou diverses optimisations. De tels changements peuvent entraîner des incidents. Le principal avantage des outils DevOps est leur intégration et leur adoption dans la communauté DevOps. Leur inconvénient est qu'ils manquent de spécifications formelles et mêmes textuelles. L’exposé présente nos premiers efforts, dans le contexte du projet ANR ForCoaLa, pour améliorer la compréhension de ces langages en se basant sur des sémantiques formelles mécanisées
Synthèse d'oligosaccharides de sulfates de chondroitine multivalents (CS) comme nouveaux outils pour l'étude des interactions protéines-CS
No full textChondroitin sulfates (CS) are structurally complex polysaccharides which belongs to the family of glycosaminoglycans (GAGs). CS are copolymers of dimeric units composed of D-glucuronic acid (D-GlcA) and 2-acetamido-2-deoxy-D-galactose (D-GalN) and contain on average one or two sulfate groups per disaccharide unit. The most common CS are CS-A (monsulfated at position 4 of the D-GalN), CS-C (monosulfated at position 6 of the D-GalN) and CS-E (disulfated at position 4 and 6 of the D-GalN). These structures are ubiquitously present on the cell surface as well as in the extracellular matrix. Due to their rich structural diversity, CS play an important role in a large number of biological processes, such as cell adhesion, cartilage homeostasis and neuronal development. Defect in their biosynthesis or in the mechanism of recognition with various proteins contribute to several diseases including osteoporosis, Alzheimer disease or cancer. The objective of this project is to develop and synthesize multivalent CS oligosaccharides composed of CS-A, CS-C or CS-E oligosaccharides (from di- to hexasaccharide) anchored on various cores in order to study CS-proteins interactions. Our strategy relies on the ligation of new CS oligosaccharides fragments bearing an azido group on the aglycone and various platforms (aromatic or aliphatic, proteins, cyclodextrins) bearing a terminal alkyne, via click chemistry (CuAAC) to build new multivalent CS oligosaccharides. Five new variously sulfated CS oligosaccharides and twelve new multivalent oligosaccharides were synthesized. The multivalent compounds will be assessed for their binding with different proteins (lectins, cathepsins) thanks to various ongoing collaborations.Les sulfates de chondroïtine (CS) sont des macromolécules polysaccharidiques complexes appartenant à la famille des glycosaminoglycanes (GAGs). Les CS sont constitués d'une unité disaccharidique répétitive composée d'un acide D-glucuronique (D-GlcA) et d'une 2-acétamido-2-désoxy-D-galactosamine (D-GalN) et contiennent en moyenne un ou deux groupements sulfates par disaccharide. Les CS les plus courants sont les CS-A (monosulfaté en position 4 de la D-GalN), CS-C (monosulfaté en position 6 de la D-GalN) et les CS-E (disulfatés en position 4 et 6 de la D-GalN). Ils interviennent dans de nombreux processus biologiques tels que l'homéostasie tissulaire du cartilage mais également l'adhésion cellulaire ou la croissance neuronale. Une déficience dans la biosynthèse des CS ou dans leur mécanisme de reconnaissance avec certaines protéines est à l'origine de différentes pathologies comme l'ostéoporose, certains cancers ou encore la maladie d'Alzheimer. L'objectif de ce projet est de développer et de synthétiser des oligosaccharides de sulfates de chondroïtines multivalents basés sur différentes plateformes afin d'étudier les interactions protéines-CS. Notre stratégie repose sur le greffage d'oligosaccharides (du di- à l'hexasaccharide) de CS-A, CS-C ou CS-E portant un groupement azido sur l'aglycone avec différentes plateformes (aromatique ou aliphatique, protéines, cyclodextrines) fonctionnalisée par un alcyne terminal par chimie click (CuAAC) afin d'obtenir de nouveaux oligosaccharides de CS multivalents. Plusieurs oligosaccharides de CS diversement sulfatés ainsi qu'une grande librairie de CS multivalents ont été synthétisés. Les objets multivalents ainsi obtenus sont en cours de tests sur différentes protéines (lectines, cathepsines) au travers de collaborations déjà effectives
Study of pharmaceuticals molecules adsorption on soils and activated carbons elaborated from agricultural residues
No full textInternational audienceWater monitoring evidence the presence in the different water bodies of several organic emerging pollutants (OEP), some of them being ubiquitous, persistent, biologically active nature, and for certain endocrine disruptors. Their occurrence may be related to the insufficient reduction of some pollutant from wastewater treatment plants (WWTP). There is thus a growing need to develop innovative and more efficient eco-processes to reduce OEP concentrations all the more since the effluent of WWTP can be used for irrigation or watering municipal garden. This process called “water reuse”, permits to limit the use of potable water for irrigation. In the BIOSEPUR project, funded by the Centre-Val de Loire region, we aim at developing innovative wastewater treatment solutions from agricultural plant waste in order to reduce the concentration some OEP, and to assess the impact of water reuse on the soil and receiving underground water on the other hand. The analysis of treated waste water from the studied WWTP highlighted the presence of 11 EOP with concentrations greater than 0.1µg/L each. The molecules were mainly pharmaceuticals (such as carbamazepine, oxazepam, diclofenac, atenolol, sulfamethoxazole) but also industrial molecules (such as benzotriazole and tolyltriazole) and AMPA, that is both a degradation product of the pesticide glyphosate and of organic phosphonates used in laundry detergents. We studied the sorption of Benzotriazole (BZT) and atenolol (ATN) on 2 soils (sand and sandy clay) sampled in a municipal garden effectively irrigated using treated wastewater by the mean of adsorption isotherms. For our tests, we weighted 20 g of soil and 20 mL of liquid containing increasing concentrations of the targeted molecule, all other conditions being identical otherwise. Sorption capacity of the 2 soils sampled were different, sorption being higher on the sandy soil. The BS soil showed a greater adsorption capacity than the PP soil for both molecules. The adsorption of ATN on both soils was higher on both types than those of BZT. In parallel of this study, agricultural residues (rapeseed straw, flax and swichtgrass) were transformed into activated carbons (AC) in the context of biomass valorization. Adsorption kinetics and isotherms of carbamazepine and sulfamethoxazole were carried out to estimate the adsorption capacity of these ACs. The next step in the study is to install a column of AC from agricultural residues in the wastewater treatment plant and make the link with what can be observed in soils
The Kinetic Study of High-Temperature Oxidation of Neopentane in a Jet-Stirred Reactor
No full textInternational audienceNeopentane oxidation chemistry has been subject to a particular interest as it is considered to be an ideal fuel for modeling the oxidation of alkanes due to its unique symmetrical structure. In the present study, the hightemperature oxidation of neopentane was studied in a jet-stirred reactor. The experiments for lean (φ = 0.5), stoichiometric (φ = 1.0) and rich (φ = 2.0) mixtures were carried out for residence times ranging from 0.05 to 0.24 s, at 1 atm and at two different constant temperatures of 1050 and 1100 K. Reaction intermediates and products were quantified by gas chromatography (FID/TCD). In addition, low-temperature experiments were conducted at 590-870 K at 1 atm for a residence time of 6 s and the concentrations of hydroperoxyl radical, hydrogen peroxide, water and formaldehyde were measured by cavity ring-down spectroscopy with continuous wave light (cw-CRDS). Furthermore, a recently presented kinetic mechanism in literature particularly focusing on the low-temperature oxidation of neopentane was improved. The modified mechanism agrees better with the present experimental data than the original mechanism that underpredicted neopentane reactivity at all conditions, although still further improvements are needed. Improvements were mainly achieved by modifying the rate constant of unimolecular decomposition of neopentane to tert-butyl and methyl radicals, a sensitive reaction at all conditions. The modified mechanism appears to still perform well at the low-temperature conditions. Moreover, the modifications were found having no considerable impact on simulating shock-tube ignition delay times from literature. Finally, a reaction pathway analysis was carried out to reveal the decomposition routes of the fuel