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Characterization of the Orphan Cytochrome P450 CYP135B1 from Mycobacterium tuberculosis : Involvement in Metabolism but Not in the Antibacterial Activity of the Antitubercular Drug SQ109
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Self‐Photosensitizing Cobalt Complexes for Photocatalytic CO<sub>2</sub> Reduction Coupled with CH<sub>3</sub>OH Oxidation
No full textInternational audienceThe use of metal complexes as homogeneous molecular catalysts has attracted considerable attention regarding photocatalytic CO2 reduction. Enhancing these complexes with photosensitivity and photooxidation capabilities, aiming to create multifunctional molecular devices, presents significant challenges. In response to these challenges, we successfully designed and synthesized three innovative metal complexes. The complexes demonstrate a remarkable ability to perform CO2 photoreduction in tandem with methanol photooxidation, allowing for the simultaneous production of formic acid without requiring additional photosensitizers and electron sacrificial reductants. An optimal turnover number (TON) value of 855 was obtained under simulated sunlight. Even under natural sunlight, the TON can reach 207, much higher than the value of the physical mixture of the photocatalytic reductive and oxidative moieties. Spectroscopic studies and density functional theory (DFT) calculations revealed that integrating reduction and oxidation sites in one molecular catalyst can promote charge transfer kinetics and enhance activity for CO2 reduction and methanol oxidation. This is the first report that non‐noble metal homogeneous catalysts can simultaneously possess photosensitivity, photoreduction, and photo‐oxidation functions, offering new insights into designing homogeneous catalysts for artificial photosynthesis
A sustainable approach to energy storage in buildings: the first rechargeable geopolymer-based battery
No full textInternational audienceThis study presents a novel metakaolin-based geopolymer rechargeable battery with Zn as negative electrode and MnO2 as positive electrode, demonstrating superior energy storage performance of about 3.3 W h L−1. Despite challenges, our findings highlight the potential for integrating energy storage into building materials, paving the way for sustainable infrastructure development
Metaverse For Battery Manufacturing: Connecting Students From Different Geographical Locations To Solve Battery Manufacturing Problems In The Virtual Reality Space
No full textInternational audienceLaboratory practices are essential to prepare students and professionals to drive future innovations in the field of energy storage and conversion. However, universities and industries working in the battery field encounter challenges such as effective training on battery production complexities, mostly due to the lack of access to battery prototyping facilities or the limited availability of battery manufacturing pilot lines for training purposes. This Concept introduces an innovative educational platform in Virtual Reality (VR) named Battery Manufacturing Metaverse (BMM). BMM promotes accessibility and collaborative learning of Lithium Ion Battery (LIB) manufacturing through an interactive and flexible VR representation of a LIB manufacturing pilot line. It enables collaboration among individuals from different geographical locations. Users can explore electrode and cell chemistries and adjust manufacturing parameters with informative feedback from a cell’s composition to the functioning of the manufacturing equipment. BMM does it with real‐time collaboration using avatars and voice chat. This platform aims to connect university students of i‐MESC, an Erasmus+ MSc. Program, enabling seamless knowledge sharing and training. BMM represents a transformative step in battery research and education, offering an immersive, interactive environment without geographical barriers to pave the way towards global education and safe training in the energy sector
Hot electrons and cold holes: operation, efficiency and design of a two-temperature hot-carrier solar cell
No full textInternational audienceHot-carrier solar cells (HCSCs) offer potential for enhancing the energy-conversion efficiency of photovoltaic devices up to 86%. However, most HCSC models to date assume that electrons and holes have the same temperature, while many reports in III-V materials indicate that electrons can be much hotter than their counterparts. We present here a detailed balance HCSC model that includes different temperatures for electrons and holes. We focus on the impact of the temperature imbalance on the voltage of such a HCSC, and on its power-conversion efficiency. Surprisingly, a temperature imbalance at a fixed effective temperature leads to a slight power-conversion efficiency increase, up to 1-2 percentage points, primarily due to an increase in fill factor and possibly of opencircuit voltage. Yet, we show that the knowledge of the effective temperature alone is sufficient to design a satisfying HCSC
Ionic liquid as a template and a carbon source for particle engineering and coating of Na3V2(PO4)2F3-yOy
No full textInternational audienceTopochemical synthesis under ionothermal conditions provides a unique pathway for obtaining the polyanionic electrode material Na3V2(PO4)2FO2 with particles exhibiting a distinctive 2D platelet morphology. This morphology directly originates from the VOPO4·2 H2O precursor through a synthesis process involving water molecules extraction followed by fluorine and sodium insertion in the interlayer space while preserving the overall covalent bond network. This synthesis approach gives the possibility to engineer the active material particles shape through a design of the precursor, while maintaining the same reaction conditions. Herein, three different VOPO4·2 H2O with distinct particle sizes and morphologies were synthetized to evaluate the impact on the resulting Na3V2(PO4)2FO2 electrochemical performance. The optimal material was sintered under argon flow to transform the ionic liquid-based surface layer into a carbon coating and enhance the active material electronic conductivity. The particles morphology optimization using ionic liquid as templating-agent allowed to improve specific capacity from 56 mAh/g to 83 mAh/g at 1 C, while the further carbonization of the ionic liquid surface layer permits to increase active material capacity up to 103 mAh/g, demonstrating the benefits of surface modification
Enhancement of hot carrier effect and signatures of confinement in terms of thermalization power in quantum well solar cell
No full textInternational audienceA theoretical model using electron–phonon scattering rate equations is developed for assessing carrier thermalization under steady-state conditions in two-dimensional systems. The model is applied to investigate the hot carrier effect in III–V hot-carrier solar cells with a quantum well absorber. The question underlying the proposed investigation is: what is the power required to maintain two populations of electron and hole carriers in a quasi-equilibrium state at fixed temperatures and quasi-Fermi level splitting? The obtained answer is that the thermalization power density is reduced in two-dimensional systems compared to their bulk counterpart, which demonstrates a confinement-induced enhancement of the hot carrier effect in quantum wells. This power overall increases with the well thickness, and it is moreover shown that the intra-subband contribution dominates at small thicknesses while the inter-subband contribution increases with thickness and dominates in the bulk limit. Finally, the effects of the thermodynamic state of phonons and screening are clarified. In particular, the two-dimensional thermalization power density exhibits a non-monotonic dependence on the thickness of the quantum well layer, when both out-of-equilibrium longitudinal optical phonons and screening effects are taken into account. Our theoretical and numerical results provide tracks to interpret intriguing experimental observations in quantum well physics. They will also offer guidelines to increase the yield of photovoltaic effect based on the hot carrier effect using quantum well heterostructures, a result critical to the research toward high-efficiency solar cell devices
Journée Métal France 2025 - Protection & Conservation du Patrimoine MétalliqueLe Métal en danger et les dangers du Métal
No full textInternational audienceThe main aim of protecting our metal heritage is to ensure that it can be passed on to future generations. But beyond the aspects of preventive or curative protection, the durability of the metal, of its cultural, social and artistic vector, is also a priority. This applies just as much to recurring phenomena caused by deterioration or pollution, as it does to 'dramatic' events, from the scale of a workshop to that of a building. This also applies to the rarer cases where the dangers of metal as a source of pollution can also be considered a posteriori as 'positive' elements of human activity and serve as a historical marker.For this METAL France day, the papers will focus on the question of identifying risks (environment and metal concerned) and preventing them. Topics will include the deterioration of metal heritage and risk prevention in "extreme" cases (shipwrecks, war, etc.) or "simple" incidents or blunders (fire, flooding). It will also cover emergency response to damage, post-damage removal, development of sensors and preventive solutions. The dangers of metal for heritage also covers cases where metal presents a danger to the environment (toxic and radioactive emissions (asbestos, mercury, beryllium, lead, etc.), pollution (peat bogs, aquatic environments, etc.), while sometimes being a remarkable trace of human activity.Finally, this truly interdisciplinary day will look at medium-term conservation in 'usual' contexts (museums, private collections, local authorities, etc.) as well as 'hostile' contexts (e.g. aggressive environments, polluted sites, armed conflicts, complex administrative procedures, etc.).These aspects will be addressed through case studies on sites and in laboratories, feedback from field experience and dedicated methodological approaches.La protection du patrimoine métallique a pour principale objectif d’en permettre la transmission. Mais, au-delà des aspects de protection préventive ou curative, la pérennité du métal, de son vecteur culturel, social et artistique, est aussi à privilégier. Ceci concerne tout autant les phénomènes récurrents induits par la dégradation ou la pollution, que les évènements « dramatiques » de l’échelle de l’atelier à celui d’un bâtiment. Cela concerne des cas, plus rares, où les dangers du métal comme source de pollution, peuvent aussi être considérés a posteriori comme des éléments « positifs » d’activités humaines et servir de marqueur historique.Pour cette journée METAL France, les communications seront centrées sur la question de l’identification des risques (environnement et métal concerné) et de leur prévention. Sera ainsi abordée la dégradation du patrimoine métallique ainsi que la prévention des risques dans les cas « extrêmes » (naufrages, guerre...) ou de « simples » incidents ou maladresses (incendie, inondation). Elle traitera également des interventions d’urgence après sinistre, retraitements après sinistre, mise au point de capteurs et solutions préventives. Les dangers du métal pour le patrimoine, concerne aussi les cas où le métal présente un danger pour l’environnement (émanations toxiques et radioactives (amiante, mercure, béryllium, plomb…), pollution (tourbières, milieu aquatique, ...), tout ou étant parfois un remarquable traceurs d’activités anthropiques.Enfin, cette journée véritablement interdisciplinaire abordera la conservation à moyen terme en contexte « usuel » (musée, collections privées, collectivités…) mais aussi « hostile » (ex. milieu agressif, site pollué, conflits armés, complexité administrative, …).Ces aspects seront abordés par des cas d’études sur sites et en laboratoire, des retours d’expérience de terrain et aussi via des approches méthodologiques dédiées
Machine learning-driven optimization of gas diffusion layer microstructure for PEM fuel cells
No full textInternational audienceThe Gas Diffusion Layer (GDL) is a vital component within Proton Exchange Membrane Fuel Cells (PEMFCs), playing a crucial role in mass and heat transport. Enhancing GDL microstructures directly improves transport properties, thereby leading to more efficient and durable PEMFCs. In this study, we developed a novel machine learning methodology to optimize the GDL microstructure and properties. The developed optimization framework demonstrated high efficacy, with an R2 score 95 % in 6 out of 7 properties and a R2 score 90 % for the GDL-Micro-Porous Layer (MPL) contact resistance. We validated our machine learning approach by comparing the predicted GDL properties to those calculated through digital characterization using physics-based methods from the stochastically generated GDL, using the optimal manufacturing parameters identified by the optimizer. Our machine learning model predicted accurately 7 GDL properties decreasing the computational cost from 3 to 4 h wall time (physical model) to 3 s wall time. Results show that low fiber concentration accompanied by low compression ratio achieve maximum diffusivity and minimum GDL-MPL contact resistance. Furthermore, prioritizing maximum electrical and/or thermal conductivities while minimizing GDL-MPL contact resistance require high fiber concentration with high compression ratio. This optimization strategy shows significant potential for improving gas transport, water management, efficient current collection, and thermal regulation within PEMFCs
Homogeneous Linewidth Behaviour of Narrow Optical Emitters at Sub-kelvin Temperatures
No full textInternational audienceWe explore the properties of ultra-narrow spectral holes in ensembles of solid-state emitters in crystals over a range of sub-kelvin temperatures, with a focus on their potential application in frequency stabilization schemes as an alternative to ultrastable cavities. We investigate how the parameters used to burn the spectral hole impact its shape, and how these factors determine the minimum achievable linewidth. In addition to the stability of the hole's center frequency, the linewidth and contrast play a crucial role in frequency locking. At sub-kelvin temperatures, the temperaturedependent T^7 broadening from two-phonon Raman scattering is expected to be negligible, and the spectral hole's linewidth should therefore remain constant in this interval. We observe however a linear broadening with increasing temperature, highlighting the need for further investigation into the mechanisms governing the linewidth at ultra-low temperatures