Portail HAL UHA (Université de Haute-Alsace)
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Urban trees species classification using Sentinel-2 and Planetscope satellite image time series
No full textInternational audienceUrban trees play an important role in the city's thermal comfort, carbon storage capacity, rainwater infiltration, capture of some pollutants or to enhance biodiversity. The classification of tree species in urban areas is essential for monitoring their health and distribution, particularly in the context of increasingly frequent heatwaves and global warming. In this study, we present a deep learning-based approach to classify the 20 most representative urban tree species in Strasbourg using Satellite Image Time Series (SITS) from Sentinel-2 and PlanetScope. We implement and compare three stateof-the-art models used for Time Series Classification (TSC) -InceptionTime, H-InceptionTime, and LITE -augmented with sensor fusion (features fusion) to exploit the complementary spectral and temporal information from both sensors. Our results show that the sensor fusion approach significantly improves classification accuracy, with the best scores for H-InceptionTime model with an accuracy of 69%. Also, the error can be explained by the specific spatial organisation of the trees in urban areas, where dense and heterogenous tree distribution inside parks is more prone to errors than aligned ones
French Universities in the Light of Responsible Digital Transformation
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Photo matériaux actifs par absorption à deux photons. Application à l’encodage réversible de données
No full textThe work of this thesis focused on the development of photoactive materials exploiting two-photon absorption (2PA) for optical data storage. The main objective is to propose information storage methods using optical techniques based on two-photon absorption. To this end, two approaches have been explored: the optimization of photochromic molecular liquid crystals and the development of octupolar photoinitiators for 3D stereolithography. The first part of this work presents the state of the art. In the second part, we studied 24 chromophores by varying three structural parameters: the multipolar organization (quadrupoles vs. octupoles), the length of electronic delocalization, and the nature of the electron-donating substituents. Our results show that quadrupoles offer the best trade-off between 2PA efficiency and compact structure, but at the expense of the photochromic functionality due to a significant lowering of the excited state energy. The third part focuses on the valorization of octupolar photoinitiators incorporating o-carborane derivatives, which promote a photoinduced charge transfer. These systems were used in 3D stereolithography to generate photopolymerized structures with an ON/OFF luminescence switching function at the micrometric scale. This work thus contributes to a better understanding of structure/property relationships in molecular engineering for 2PA-activatable materials.Mes travaux de recherche portent sur le développement de matériaux photo actifs exploitant l’absorption à deux photons (2PA) pour le stockage optique de données. L’objectif principal est de proposer des méthodes de stockage de l’information en utilisant des techniques optiques basées sur l’absorption à deux photons. Pour cela, deux axes ont été explorés : l’optimisation de cristaux liquides moléculaires photochromiques et le développement de photoamorceurs octupolaires pour la stéréolithographie 3D. La première partie de ce travail présente l’état de l’art. Dans la seconde partie, nous avons étudié 24 chromophores en faisant varier trois paramètres structurels : l’organisation multipolaire (quadrupôles vs. octupôles), la longueur de délocalisation électronique et la nature des substituants électrodonneurs. Nos résultats montrent que les quadrupôles offrent le meilleur compromis entre efficacité 2PA et structure compacte, mais au détriment de la fonctionnalité photochromique, en raison d’un abaissement trop important de l’énergie de l’état excité. La troisième partie est consacrée à la valorisation de photoamorceurs octupolaires intégrant des dérivés o-carboranes, favorisant un transfert de charge photoinduit. Ces systèmes ont été utilisés en stéréolithographie 3D pour générer des structures photopolymérisées avec une commutation luminescente ON/OFF à l’échelle micrométrique. Ces travaux contribuent ainsi à une meilleure compréhension des relations structure/propriétés en ingénierie moléculaire pour les matériaux activables en 2PA
Rousseau, "De l'art de jouir et autres fragments". Présentation et édition critique
No full textInternational audienceCritical edition comprising an introductory overview, the text with all variants, and explanatory notes.Edition critique comportant une présentation d'ensemble, le texte avec l'ensemble des variantes et des notes explicatives
Enhancing surface area of HNO<sub>3</sub>-activated digestate-derived biochar for methylene blue adsorption: RSM-CCD optimization, DFT-MD calculations, and mechanistic study
No full textInternational audienceThis study highlights the potential of anaerobically treated sewage sludge, a by-product of anaerobic digestion (AD) produced in large quantities by wastewater treatment plants (WWTPs), which is further thermally activated to yield biochar. This biochar serves as a template for HNO3 modification, enabling efficient pollutant remediation. Herein, we investigated the removal efficiency of methylene blue (MB) using modified biochars under different HNO3> concentrations. The BC-HN9 exhibited the best MB sorption performance and was selected for further investigations, including characterization, evaluation of adsorption parameters, and investigations of kinetic and isotherm models. It was determined that chemical and physical interactions contribute to MB sorption, with the maximum adsorption capacity of 176.05 mg·g−1. Additionally, thermodynamic investigations confirmed that the process is endothermic and occurs spontaneously. The adsorption mechanism of MB was analyzed using DFT, radial distribution function (RDF), Monte Carlo (MC) and molecular dynamics (MD) calculations in combination with advanced techniques. The findings indicate that adsorption is facilitated by electrostatic interactions, pore filling, H-bonding, as well as n-π and π-π interactions. This method demonstrates a scalable approach to producing activated biochars, providing both an effective pathway for fabricating high-value carbon materials and a practical means of mitigating environmental pollution associated with biomass waste
Advanced contaminant removal through synergistic interactions of montmorillonite, CoFe2O4 nanoparticles, and surfactants: Combining theoretical and experimental approaches
No full textInternational audienceThis study addresses the critical challenge of toxic dye contamination in water resources, with a particular focus on the efficient removal of cationic malachite green (MG) dye from aqueous solutions. The research involves a two-fold approach, initially focusing on the process of altering montmorillonite clay through the incorporation of Surfactants, specifically sodium dodecyl sulfate (SDS) and cetyltrimethylammonium bromide (CTAB). Following that, the investigation delves into the real-world application of this modified clay mineral in removing MG dye from water-based solutions. The synthesized nanocomposite exhibited a highly negative surface charge and demonstrated excellent capabilities for MG molecules, achieving a maximum adsorption capacity of 1245.20 mg/g. Furthermore, the equilibrium adsorption data closely aligned with the theoretical predictions of the Langmuir model (R2 = 0.99), suggesting homogeneous adsorption and the formation of a monolayer of MG molecules on the nanocomposite surface. The surface modification of montmorillonite following surfactant plays a crucial role in enhancing the adsorption properties of the clay. Further modifications are carried out to harness the synergistic effects of the incorporated surfactants, resulting in enhanced adsorption capacity. The incorporation of magnetic nanoparticles of CoFe2O4 adds versatility to the modified clay, potentially enabling easier separation from treated wastewater using magnetic fields. The research combines various techniques, including molecular dynamics simulations, Density Functional Theory with dispersion correction (DFT-D) calculations, and Monte Carlo methodologies. This approach aims to create a tailored adsorbent material with improved performance in removing cationic dyes, thereby contributing to cleaner water resources and environmental sustainability
Unlocking MOF A520 synthesis: investigating critical parameters
No full textInternational audienceAluminium based metal–organic frameworks (MOFs) have emerged as versatile materials with applications in gas and vapor storage, catalysis, and separation. Among these, aluminium fumarate known as MOF A520 or MIL-53(Al)_Fu exhibits promising humidity scavenging properties due to its unique structure, chemical composition and porosity. However, achieving reproducible, low cost and high-yield synthesis remains a challenge. In this study, we systematically investigate the critical parameters influencing green synthesis of MOF A520. Through a hydrothermal method, we explore the impact of aluminium precursor nature and concentration, water and base concentrations in the starting mixture and reaction time. Our findings reveal optimal conditions for MOF A520 crystallization, leading to enhanced yield, purity and cost reduction. This work bridges the gap between laboratory-scale synthesis and industrial-scale production, providing insights that are not available in existing literature
Straightforward Access to Pentafluorosulfanylated Phenols and Aminophenols via [4 + 2] Diels–Alder Cycloaddition Reaction
No full textInternational audienceHere is described a theoretical and experimental study of regioselective [4 + 2] Diels-Alder cycloaddition reactions between electron-rich dienes and SF5-alkynes. These methods give straightforward and convergent access to SF5-phenols and aminophenols in short reaction sequences. Density functional theory (DFT) calculations combined with reactivity tools, activation strain model, and energy decomposition analysis provide a deeper mechanistic understanding of these Diels-Alder cycloaddition reactions involving an alkyne as a dienophile. We found that regioselectivity and reactivity originate from less destabilizing strain energy and reduced Pauli repulsion between occupied π-orbitals of the diene and dienophile, rather than from stabilizing highest occupied molecular orbital-lowest unoccupied molecular orbital (HOMO-LUMO) interactions. This can be ascribed to a higher degree of asynchronicity in the transition state of the privileged attack of the diene on the dienophile
Correlation of acid sites with morphology of layered silicates
No full textInternational audienceAcid sites of clay minerals are active to catalyze numerous organic reactions. Previous studies had focused on the types and strength of these sites by correlating them with acid, pillaring or heat treatments, but the relation of acid sites with clay mineral morphology is not well understood. In this study, the synthesis of samples havingsimilar chemical composition and structure, but different morphology characteristics was realized. The surface of samples was characterized by low-pressure argon adsorption at 77 K. The acid sites were probed by thermaldesorption of 2-phenylethylamine. Three sites of different acid strength were identified. Whereas the assignment of these sites to basal and edge surfaces remains debatable, the method of thermal desorption of 2-phenylethylamine could clearly distinguish different sites related to homogenous and heterogeneous surfaces
