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The Influence of Microstructural Heterogeneities on the Thermal Response of CFRTP Composite Tapes at the Ply-Scale
No full textInternational audienceThe thermal response of Carbon Fiber Reinforced Thermoplastic (CFRTP) tapes under short-term localized heating is critical for automated manufacturing processes. Conventional homogenized models often overlook microstructural heterogeneities that can promote non-uniform heating and affect the quality of the consolidated part. In this work, we combine insights from infrared thermography with finite element simulations at the fiber scale built on micrographs extracted from real tapes to quantify the effect of individual heterogeneities—including surface roughness, thickness variation, fiber agglomeration, and porosity—on thermal propagation. Three modeling configurations were compared under identical conditions: a full microstructure model; a simplified geometry-aware model (where the real geometry is taken into the account, including the surface roughness and thickness variability, but the properties of the domain are considered as a homogeneous-equivalent material); and a homogeneous-equivalent baseline with flat borders and uniform thickness. Results show that porosity effects depend strongly on location and orientation: large, horizontally aligned pores near the heated surface produce the highest gradients. Surface roughness, on the other hand, exerts dominant effects on surface temperature non-uniformity with respect to thickness variation and fiber distribution. These findings demonstrate that accounting for microscale heterogeneities is essential to achieve more accurate, optimized, and application-tailored analyses of CFRTP tapes in advanced manufacturing
Modéliser mathématiquement la mucoviscidose
No full textInternational audienceLe projet MucoReaDy vise à modéliser le transport du mucus dans les poumons pour évaluer son bon fonctionnement, en particulier chez les patients atteints de mucoviscidose. En combinant des prélèvements cliniques et des équations décrivant le mucus bronchique, le modèle identifie des paramètres permettant d’identifier un mucus sain ou pathologique. Cette cartographie permet de suivre l’évolution des patients sous trithérapie et de déterminer des signes avant-coureurs de dégradation de leur santé
A multiport transistor characterisation technique including mutual inductances using 2-Port VNA
No full textInternational audienceThis paper introduces a novel measurement technique for 4-pin SiC MOSFET transistors with TO-247-4 packaging, accounting for mutual inductances and utilizing a two-port vector network analyzer (VNA). The proposed method involves six distinct measurements to obtain a 4x4 S-parameter matrix, which is subsequently reduced by implementing a “virtual ground” in Advanced Design System (ADS) to achieve optimal grounding for one of the transistor's pins. This approach ensures ideal grounding conditions for accurate measurements and allows ease of power and driver gate inductance loops extraction. Additionally, the paper details the RLC extraction process of the evaluated SiC transistor and compares the extracted capacitance values with those specified in the datasheet
eHPWAS'25: Thirteenth International workshop on e-health pervasive wireless applications and services
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Exploring interface tension as a tool to control the morphology of binary organic semiconductor nanoparticles prepared by nanoprecipitation
No full textInternational audienceThe ability to control the morphology of organic semiconductor nanoparticles is of paramount importance for applications in organic photovoltaics, photocatalysis, and photo-triggered biological applications. In this paper, we demonstrate that nanoprecipitation is a powerful technique to provide a variety of morphologies in binary blends of organic semiconductors. By investigating seven different donor : acceptor couples we demonstrate that the resulting morphology is primarily governed by the interfacial tension between the two photo-active components. The structure of the particles is also influenced by the interactions between the medium and the materials. Indeed, we show that the medium should not be considered solely as water; rather, the surfactant employed and the organic solvent in which the materials are dissolved also play crucial roles. By manipulating these parameters, P3HT : PC61BM nanoparticles were produced via nanoprecipitation, exhibiting either intermixed, Janus, or core-shell morphologies depending on the dispersive medium. Cryo-TEM and STEM-EDX were utilized to image the internal structure of the particles for couples involving PC61BM and non-fullerene acceptors (NFA) such as Y6 and a polymer P(DTS-DAP). The increased surface tension between the donors and PC61BM generally results in the formation of Janus nanoparticles. Conversely, the NFAs used in this study exhibit a higher compatibility with the donor, thereby promoting in some cases an intermixed structure
Nonpolar Thermodynamically Stable Nanodrop Emulsions with Film-Forming Capacity
No full textInternational audienceObtaining thermodynamically stable non-aqueous microemulsions has so far required at least one component to be polar. This requirement introduces limitations when strictly non-polar media are needed. In this report, we describe the spontaneous formation of completely non-polar, thermodynamically stable microemulsions by incorporating a semifluorinated alkane that acts as a "solvotrope" into a mixture of hydrocarbon and fluorocarbon oils. These microemulsions are composed of narrowly dispersed nanodrops of one liquid within the other, leading to the formation of both hydrocarbon-in-fluorocarbon and fluorocarbon-inhydrocarbon microemulsions depending on the ternary mixture composition. We also report a phase separation at the microemulsion-air interface: when the hydrocarbon oil serves as the continuous phase, the fluorocarbon nanodrops rapidly and preferentially adsorb at this interface. This leads to the formation of a thin hydrophobic and lipophobic surface film. These findings enhance our understanding of microemulsions and the ouzo effect, which were previously confined to polar systems, now extending their relevance to completely non-polar systems and opening up new possibilities for applications
Re-assessment of mercury isotope mass-independent fractionation during monomethylmercury photodegradation pathways in freshwater
No full textInternational audiencePhotodegradation of monomethylmercury (MMHg) in surface waters induces mass-dependent and massindependent fractionation (MIF) of mercury (Hg) isotopes, providing information on the fate of Hg. We aim to understand the mechanisms of MMHg photodegradation and Hg isotopic fractionation affected by physicochemical factors in freshwater. We investigated the MMHg photodegradation under anoxic and oxic conditions. In addition, MMHg solution was exposed to simulated solar radiation wavelength including or not short UVB (280-305nm). Results for Hg species remaining in the solution showed lower ε Δ 199 Hg in anoxic conditions within the range from -8.5 ± 0.6 ‰ to -16.9 ± 1.9 ‰ and -10.8 ± 0.7 ‰ to -29.3 ± 6.0 ‰ with and without short UVB, respectively, than oxic conditions from -16.8 ± 4.0 ‰ to -19.6 ± 4.1 ‰ and -29.1 ± 4.5 ‰ to -33.0 ± 7.7 ‰ regardless of purging mode. This is probably caused by slower spin interconversion in oxic conditions. In anoxic conditions, the average Δ 199 Hg/Δ 201 Hg slope increased from 1.42 ± 0.04 to 1.67 ± 0.08 with short UVB. Our study supports the finding that Δ 199 Hg/Δ 201 Hg generated by the photochemical magnetic isotope effect (MIE) varies significantly according to the UV spectral ranges. This highlights the importance of UV light interactions for Hg and other elements featuring photochemical MIE, providing a new basis for interpreting Hg odd-MIF signature
Unlocking self-discharge: Unveiling the mysteries of electrode-free Zn-MnO2 batteries with advanced in situ techniques in mild acid aqueous electrolytes
No full textInternational audienceWe introduce a novel approach to Zinc-MnO2 battery architecture utilizing a 3D network of carbon nanofibers as both current collector and electrode material, promising enhanced performance and longevity for large-scale energy storage. Employing mild aqueous electrolytes, we address the challenge of managing self-discharge, crucial for short-term energy storage.Advanced coupled characterization techniques, including in-situ EQCM (Electrochemical Quartz Crystal Microbalance) and high-resolution optical microscopy, elucidate self-discharge mechanisms across over multiple length scales. Findings reveal that the self-discharge is mainly at the zinc electrode due to concomitant dissolution of Zinc (corrosion) and HER (Hydrogen Evolution Reaction) phenomena. Interestingly, the corrosion current was estimated irrespective of charging protocol and remains consistent, indicating the independence of zinc corrosion kinetics from the length scale. Finally, the morphology of the zinc layer appears to be critical, suggesting that self-discharge is primarily a chemical process. This innovative design strategy offers the potential for high-performance Zinc-MnO2 batteries with extended cycle life to meet the requirements of large-scale energy storage applications