Portail HAL UHA (Université de Haute-Alsace)
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Phenothiazine Derivative-Based Photoinitiators for Ultrafast Sunlight-Induced Free Radical Polymerization and Rapid Precision 3D Printing
No full textInternational audienceIn this work, we introduce twenty-six phenothiazine derivatives (PTZs) that were designed and synthesized as visible light photoinitiators. These compounds, in combination with an amine [ethyl 4-(dimethylamino)benzoate (EDB)] and an iodonium salt [di-tert-butylphenyl iodonium hexafluorophosphate (Iod)], could furnish high-performance three-component (PTZs/EDB/Iod) photoinitiating systems that were employed for the free radical polymerization of thick films of a low-viscosity model acrylate resin, namely, trimethylolpropane triacrylate (TMPTA) under visible light and sunlight exposure. A commercial thioxanthone, i.e., isopropylthioxanthone (ITX) was selected to design a reference ITX/EDB/Iod photoinitiating system. Double bond conversions of 87% and 76% were measured for the developed and synthesized photoinitiating systems under 405 and 450 nm light-emitting diode irradiation, respectively, and a conversion as high as 70% could be determined under sunlight irradiation - about 23 times higher than the conversion obtained with the comparable system prepared with the commercial photoinitiator. The relevant photoinitiation abilities and photochemical mechanisms are comprehensively investigated by a combination of techniques including real-time Fourier transform infrared spectroscopy, UV-visible absorption spectroscopy, fluorescence spectroscopy, steady-state photolysis, cyclic voltammetry, and electron paramagnetic resonance. Notably, the exceptional performance of the photoinitiators enabled the fabrication of 3D objects with precise morphology and superior resolution through 3D printing and direct laser write techniques. These findings not only provide opportunities for efficient polymerization under artificial and natural light conditions but also pave the way for scalable, costeffective, environmentally sustainable, and green chemistry-driven curing applications
Un tribunal des idées pour discuter de transition après la fermeture d’une centrale nucléaire
No full textInternational audienceNuclear power is at the crossroads of science and society, because of the scale of the economic, political, social, environmental and ethical challenges it poses. The issues exceed by far the concerns of the scientific and expert community, which have been reignited by recent debates on the European taxonomy. Nuclear power sparks fervent controversies, oppositions and conflicts within our society. In this context, the inquiry focuses on the ability to involve young citizens in the debate on the future of a territory subsequent to the shutdown of a nuclear power plant. The underlying hypothesis highlights the value of introducing a serious game into a controversial setting, and its ability to build consensus around a new trajectory. Consequently, after presenting the framework of our case study, we will analyze the results in order to understand how students from the local middle school take hold of the future of their territory, which happens to be a controversial nuclearized territory.RésumésFrançais English Le nucléaire se trouve aux interactions entre sciences et société du fait de l'ampleur des défis économiques, politiques, sociaux, environnementaux et éthiques que cette technologie porte en elle. En effet, les questionnements qu'il suscite vont bien au-delà des questionnements scientifiques et de la communauté des experts que les débats récents autour de la taxonomie européenne ont ravivé. Le nucléaire génère des controverses passionnelles, des oppositions et des conflits dans la société. Dans ce contexte, la question porte sur la capacité à faire participer de jeunes citoyens dans le débat sur le devenir d'un territoire après la fermeture d'une centrale. L'hypothèse sous-jacente porte sur l'intérêt d'introduire un serious game dans un contexte controversé et sa capacité à faire émerger un consensus autour d'une nouvelle trajectoire. Ainsi, après avoir présenté le cadre de notre étude de cas, nous exposerons les résultats afin de comprendre comment de jeunes collégiens du territoire s'emparent du devenir de leur territoire, celui d'un territoire nucléarisé controversé.Nuclear power is at the crossroads of science and society, because of the scale of the economic, political, social, environmental and ethical challenges it poses. The issues exceed by far the concerns of the scientific and expert community, which have been reignited by recent debates on the European taxonomy. Nuclear power sparks fervent controversies, oppositions and conflicts SEARCHTout OpenEdition within our society. In this context, the inquiry focuses on the ability to involve young citizens in the debate on the future of a territory subsequent to the shutdown of a nuclear power plant. The underlying hypothesis highlights the value of introducing a serious game into a controversial setting, and its ability to build consensus around a new trajectory. Consequently, after presenting the framework of our case study, we will analyze the results in order to understand how students from the local middle school take hold of the future of their territory, which happens to be a controversial nuclearized territory.</div
Fouilles aux fortifications de Delphes – campagne d’étude et de restauration 2023
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L’information climatique au défi de tensions créatives et transnationales, le cas de NowU
No full textInternational audienceThis communication reports on the editorial adventure of the Franco-German media NowU, accessible online for young Europeans from 2021 to 2023. This digital media device proposed by France Télévision and its German counterpart, Westdeutscher Rundfunk, was intended to engage 15-25 year olds in climate action through an exemplary eco-responsible and eco-built medium. The trajectory of NowU is an opportunity to take a closer look at its format, its biases and the difficulties in finding a European audience with an unusual format. The analysis of this unprecedented digital information experience highlights tensions and constraints of a media that addresses both the challenge of climate information to meet the challenges of this issue and the challenge of its production and transnational dissemination.Cette communication rend compte de l’aventure éditoriale du média franco-allemand NowU accessible en ligne pour les jeunes Européens de 2021 à 2023. Ce dispositif médiatique numérique proposé par France Télévision et son équivalent allemand Westdeutscher Rundfunk se proposait d’engager les 15-25 ans à agir pour le climat par l’intermédiaire d’un média exemplaire écoresponsable et écoconstruit. La trajectoire de NowU est l’occasion de regarder de plus près son format, ses partis pris et les difficultés à trouver un public à l'échelle européenne avec un format inhabituel. L’analyse de cette expérience d’information numérique inédite met en évidence des tensions et contraintes d’un média relevant à la fois le défi d’une information climatique à la hauteur des enjeux de cette problématique et le pari de sa production et diffusion transnationale
Data augmentation for pathogen segmentation in vinewood fluorescence microscopy images
No full textInternational audienceIn this paper, we address the problem of segmentation of vine pathogens within fluorescence microscopy images. To our knowledge, the quantification from such images is an original problem. As a consequence, there is no available database to rely upon in order to use supervised machine learning techniques. We provide a workaround by creating realistic images containing the desired filamentary pattern and variable blur effect. Numerical results show the interest of this data augmentation technique, especially on images corresponding to difficult segmentation
Washable oil-coated structured support for passive outdoor particulate matters trapping
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Synthèse de systèmes polymères hybrides et étude de leurs propriétés non-linéaires pour la limitation optique dans l’infrarouge
No full textThe human eye, sensors, and photoreceptors can be damaged if they are submitted to laser beams with high intensities and low divergence. In the military field, an optical sensor can be damaged by pulsed laser radiations when exposed beyond its capacities. To have a protection against such threats, passive optical limiting is used. A mix between a reactive oligomer and a monomer, with methacrylate functions, is studied in the present work giving a thermoset matrix. To prevent the monomer evaporation, which results in the formation of bubbles in the final material, related to the reaction exotherm, an oligomer and a monomer with a high boiling temperature are used as precursors, giving a good alternative to a thermoplastic matrix like polymethyl methacrylate (PMMA). We report the experimental results of transient thermally induced optical nonlinearities (i.e., nonlinear refraction) in methacrylate‐based polymer filters at a nanosecond timescale, focus will be made to compare third order nonlinear refractive index from thermally induced refractive index. Optical filters are obtained by chemical bulk processes and 3D printing. In the present work, both thermoplastics and thermosets matrices were synthesized to characterize their optical limiting properties by mean of an appropriate custom‐made optical setup as well as their nonlinear refractive indices measured by the z‐scan technique. Optical measurements in the nonlinear regime are achieved at the wavelength of 1064 nm.L'œil humain, les détecteurs et les photorécepteurs peuvent être endommagés s’ils sont soumis à des rayonnements lasers de haute intensité et de faible divergence. Dans le secteur militaire, un détecteur optique peut être endommagé par des radiations lasers pulsées quand il est exposé au-delà de ses capacités. Pour avoir une protection contre ces menaces, la limitation optique est utilisée. Un mélange entre un oligomère et un monomère, avec des fonctions méthacrylates, est étudié dans ces travaux, donnant une matrice thermodurcissable. En effet, pour prévenir l’évaporation du monomère, les composés présentent une haute température d’ébullition, constituant une bonne alternative aux matrices thermoplastiques comme le polyméthacrylate de méthyle (PMMA). Les résultats expérimentaux présentent les non-linéarités optiques transitoires induites thermiquement (réfraction non-linéaire) dans les filtres polymères méthacrylates à une échelle de temps nanoseconde. L’accent est mis sur la comparaison de l’indice de réfraction non-linéaire du 3ème ordre et celui induit thermiquement. Les filtres optiques obtenus sont réalisés par un processus de polymérisation radicalaire en masse et par impression 3D. Ici, les matrices thermoplastiques et thermodurcissables sont synthétisées afin de caractériser leurs propriétés de limitation optique grâce à l’utilisation d’un système optique approprié. De plus, leur indice de réfraction non-linéaire est mesuré par la technique du Z-scan. Les mesures sont faites à une longueur d’onde de 1064nm
Segmentation/deconvolution statistique d'images du bois de vigne par champs de Markov triplets
No full textInternational audienceSegmentation/deconvolution statistique d'images du bois de vigne par champs de Markov triplet
Carbazole-Fused Coumarin Bis Oxime Esters (CCOBOEs) as efficient photoinitiators of polymerization for 3D printing with 405 nm LED
No full textInternational audienceIn this research, the innovative design and successful synthesis of two visible light photoinitiators, namely CCOBOE0 and CCOBOE1, have been confirmed through nuclear magnetic resonance (NMR) and mass spectrometry (MS). Both compounds exhibit strong absorption properties at 385, 405 and 450 nm, and FT-IR analyses have substantiated the ability of CCOBOE1 to initiate the polymerization of a trifunctional acrylate monomer (TMPTA) under these three light sources. The optimal conditions for maximizing the photoinitiation potential of CCOBOE1 were determined to be at a concentration of 2 × 10−5 mol.g−1 and under 405 nm LED irradiation. Photolysis experiments, theoretical calculations, detection of CO2 absorption peaks, and ESR experiments have all confirmed the generation of methyl radicals by CCOBOE1. Utilizing the identified optimal conditions, a “XYZ” pattern with a thickness of 963 μm and a 3D-object were successfully obtained via direct laser write (DLW) and digital light processing (DLP) 3D-printing upon irradiation at 405 nm. Additionally, differential scanning calorimetry (DSC) analyses demonstrated the promising performance of CCOBOE1 in initiating the thermal polymerization of acrylate monomers. In summary, the difunctional CCOBOE1 showed outstanding performance in both photo-initiation and thermal initiation of acrylate monomers. It provides a novel direction for the development of novel OXEs with dual activation modes
Soft-templated mesostructured TiO2 - SiO2 composites with high thermal stability
No full textInternational audienceTo overcome the drawbacks of pure mesostructured titania and in particular the low thermal stability, in this study we have investigated in detail the effect of Si4+ addition on the properties of mesostructured TiO2 prepared by combining the sol-gel process and the surfactant templating mechanism. Obtained materials have also been tested for the photodegradation of methyl orange, used as a model dye.From the SAXS and the manometry nitrogen adsorption-desorption analyses, it can be concluded that the presence of Si4+ delays the collapse of the mesopores network. Compared to the bare mesostructured TiO2, the XRD and Raman results show that the anatase and the rutile phases appear at higher temperature. The higher the Si4+ content, the higher the amorphous-anatase and rutile anatase-phase transition temperatures. The delay in the crystallization also allows the detection of the TiO2-β phase, which is an anatase phase with oxygen vacancies. These phenomena have been attributed to the « glass effect ». In that case, amorphous SiO2, which is formed during the synthesis, surrounds the titania particles and inhibits their growth, when the heating temperature is increased. By this way, the thermal stability of the mesostructured titania containing Si4+ is enhanced.Photocatalytic experiments highlight the importance of the presence of the anatase phase for the discoloration efficiency of the dye solution. Indeed, the increase of Si4+ leads to a clear decrease of the photodegradation efficiency