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[Invited] Polyoxometalate Molecular Electronics.
No full textInternational audiencePolyoxometalates (POMs) are molecular nanostructures consisting of early transition metals and oxygen [1, 2]. As molecular oxides, they possess remarkable redox properties, combining the reducibility of bulk metal oxides with the high versatility of molecular species. They undergo successive, reversible and highly adjustable mono- (or multi-) electronic reduction processes within a narrow potential range. Acting as a missing link between the metal oxides found in nanoelectronics and conventional organic or organometallic molecules, POMs have attracted an increasing interest in the field of nanoelectronics [3, 4]. In this context, we have explored various strategies to immobilize POMs onto electrodes, with the objective of improving control of the molecule/electrode interfaces [5-7]. We have investigated the electron transport properties of POM-based molecular junctions to establish relationships between the molecular structure of POMs, their electronic structures, and the properties of POM devices (e.g., conductance and switching behavior) [8]. Furthermore, POMs are polyanions, with counter cations playing a crucial role in the electron transport properties, beyond ensuring charge neutrality [9, 10]. We have demonstrated that the redox state of a POM layer can be switched by exposure to light [8] or application of an electric field, opening up new possibilities for stimulus-responsive devices. Perspectives on neuromorphic device applications will be highlighted in this presentation [11, 12].[1] M.T. Pope, A. Müller, Polyoxometalate Chemistry: An Old Field with New Dimensions in Several Disciplines, Angew. Chem. Int. Ed., 30 (2003) 34-48.[2] X. Lopez, J.J. Carbo, C. Bo, J.M. Poblet, Structure, properties and reactivity of polyoxometalates: a theoretical perspective, Chem. Soc. Rev., 41 (2012) 7537-7571.[3] D.L. Long, R. Tsunashima, L. Cronin, Polyoxometalates: building blocks for functional nanoscale systems, Angew. Chem. Int. Ed., 49 (2010) 1736-1758.[4] C. Busche, L. Vila-Nadal, J. Yan, H.N. Miras, D.L. Long, V.P. Georgiev, A. Asenov, R.H. Pedersen, N. Gadegaard, M.M. Mirza, D.J. Paul, J.M. Poblet, L. Cronin, Design and fabrication of memory devices based on nanoscale polyoxometalate clusters, Nature, 515 (2014) 545-549.[5] M. Laurans, K. Dalla Francesca, F. Volatron, G. Izzet, D. Guerin, D. Vuillaume, S. Lenfant, A. Proust, Molecular signature of polyoxometalates in electron transport of silicon-based molecular junctions, Nanoscale, 10 (2018) 17156-17165.[6] K. Dalla Francesca, S. Lenfant, M. Laurans, F. Volatron, G. Izzet, V. Humblot, C. Methivier, D. Guerin, A. Proust, D. Vuillaume, Charge transport through redox active [H7P8W48O184]33-polyoxometalates self-assembled onto gold surfaces and gold nanodots, Nanoscale, 11 (2019) 1863-1878.[7] M. Laurans, K. Trinh, K. Dalla Francesca, G. Izzet, S. Alves, E. Derat, V. Humblot, O. Pluchery, D. Vuillaume, S. Lenfant, F. Volatron, A. Proust, Covalent Grafting of Polyoxometalate Hybrids onto Flat Silicon/Silicon Oxide: Insights from POMs Layers on Oxides, ACS Appl. Mater. Interfaces, 12 (2020) 48109-48123.[8] C. Huez, D. Guérin, S. Lenfant, F. Volatron, M. Calame, M.L. Perrin, A. Proust, D. Vuillaume, Redox-controlled conductance of polyoxometalate molecular junctions, Nanoscale, 14 (2022) 13790-13800.[9] K.Y. Monakhov, Implication of counter-cations for polyoxometalate-based nano-electronics, Comments on Inorganic Chemistry, 44 (2022) 1-10.[10] C. Huez, S. Renaudineau, F. Volatron, A. Proust, D. Vuillaume, Experimental observation of the role of countercations in modulating the electrical conductance of Preyssler-type polyoxometalate nanodevices, Nanoscale, 15 (2023) 10634-10641.[11] H. Tanaka, M. Akai-Kasaya, A. TermehYousefi, L. Hong, L. Fu, H. Tamukoh, D. Tanaka, T. Asai, T. Ogawa, A molecular neuromorphic network device consisting of single-walled carbon nanotubes complexed with polyoxometalate, Nat. Commun., 9 (2018) 2693.[12] C. Huez, D. Guérin, F. Volatron, A. Proust, D. Vuillaume, Low-frequency noise in nanoparticle–molecule networks and implications for in materio reservoir computing, Nanoscale, 16 (2024) 21571-21581
Automotive battery pack standards and design characteristics: a review
No full textInternational audienceThe latest advancements and near-future trends in automotive battery packs, underlying regulatory compliance, and performance requirements are presented in this paper. In response to these specifications, high-level solutions that converge towards a standard architecture for passenger cars are provided. Transitioning to high-voltage systems (400 V-800 V), which support charging power levels above 350kW, reduces the required current. This, in turn, lowers the weight and volume of cell/module connectors and high-voltage cables in the drivetrain. Additionally, optimization strategies are crucial for enabling fast charging in all conditions, especially in cold climates, while ensuring safe operation, preventing thermal runaway, and reducing charging times to under 20 minutes. Also, advances in energy density (up to 300 Wh/kg) and battery capacities make advancements in enhancing the electric vehicle's range beyond 1000 km per charge. Key factors such as electrical performance, safety, mechanical integrity, reliability, endurance, environmental conditions, and diagnostics are examined. This study explores the next generation of cost-effective and high-performance battery systems and discovers near-future battery technologies, including sodium-ion chemistry and rare-earth-free alternatives, as well as battery applications in aviation
Optimisation de transistors totalement verticaux en GaN sur silicium pour la conversion de puissance
No full textbest poster awardInternational audienceMost electrical components on the power conversion market are IGBT or vertical MOSFET made of Si. However, their performances are limited by silicon physical properties (low thermal conductivity, low breakdown electric field...). Other materials like SiC and GaN have emerged has a replacement. However silicon carbide, even if very well suited for power conversion, remains expensive as it cannot be grown on silicon but only pricey bulk substates. For this reason, GaN-on-Si is a more promising solution: it has similar properties to SiC but for a redude cost. This poster prevents the research done at IEMN to develop a fabrication process for efficient and competitve fully vertical GaN-on-Si MOSFET, since such process remains immature to this day.La plupart des composants électriques sur le marché de la conversion de puissance sont des IGBT ou des MOSFET verticaux en silicium. Cependant, leurs performances sont limitées par les propriétés physiques du silicium (faible conductivité thermique, faible champ électrique de claquage...). D'autres matériaux tels que le SiC et le GaN ont fait leur apparition pour les remplacer. Cependant, le carbure de silicium, même s'il est très bien adapté à la conversion de puissance, reste coûteux car il ne peut pas être cultivé sur du silicium, mais uniquement sur des substrats volumineux onéreux. C'est pourquoi le GaN-on-Si est une solution plus prometteuse : il présente des propriétés similaires à celles du SiC, mais à un coût réduit. Cette affiche présente les recherches menées à l'IEMN pour développer un procédé de fabrication efficace et compétitif de MOSFET GaN-on-Si entièrement verticaux, car ce procédé reste immature à ce jour
Mamba Adaptive Anomaly Transformer with association discrepancy for time series
No full textInternational audienceAnomaly detection in time series poses a critical challenge in industrial monitoring, environmental sensing, and infrastructure reliability, where accurately distinguishing anomalies from complex temporal patterns remains an open problem. While existing methods, such as the Anomaly Transformer leveraging multi-layer association discrepancy between prior and series distributions and Dual Attention Contrastive Representation Learning architecture (DCdetector) employing dual-attention contrastive learning, have advanced the field, critical limitations persist. These include sensitivity to short-term context windows, computational inefficiency, and degraded performance under noisy and non-stationary real-world conditions. To address these challenges, we present MAAT (Mamba Adaptive Anomaly Transformer), an enhanced architecture that refines association discrepancy modeling and reconstruction quality for more robust anomaly detection. Our work introduces two key contributions to the existing Anomaly transformer architecture: Sparse Attention, which computes association discrepancy more efficiently by selectively focusing on the most relevant time steps. This reduces computational redundancy while effectively capturing long-range dependencies critical for discerning subtle anomalies. A Mamba-Selective State Space Model (Mamba-SSM) is also integrated into the reconstruction module. A skip connection bridges the original reconstruction and the Mamba-SSM output, while a Gated Attention mechanism adaptively fuses features from both pathways. This design balances fidelity and contextual enhancement dynamically, improving anomaly localization and overall detection performance. Extensive experiments on benchmark datasets demonstrate that MAAT significantly outperforms prior methods, achieving superior anomaly distinguishability and generalization across diverse time series applications. By addressing the limitations of existing approaches, MAAT sets a new standard for unsupervised time series anomaly detection in real-world scenarios. Code available at https://github.com/ilyesbenaissa/MAAT.</div
On the Trustworthiness of Spiking Neural Networks and Neuromorphic Systems
No full textInternational audienceNeuromorphic computing offers a promising solution for realizing energy-efficient and compact Artificial Intelligence (AI) systems. Implemented with Spiking Neural Networks (SNNs), neuromorphic systems can benefit from SNN characteristics, such as event-driven computation, event sparsity, biological plausibility, etc., to achieve high performance and energy efficiency, an aspect vital for the realization of AI at the edge. Although SNNs are biology-inspired structures, their use in mission-and safety-critical applications raises multiple concerns around the trustworthiness of neuromorphic hardware due to various intrinsic and extrinsic reliability and security issues. Hence, adequately studying the dependability of SNNs and neuromorphic hardware accelerators becomes of utmost importance, in order to expose and harden against potential vulnerabilities, so that a reliable and secure operation is ensured. This paper presents an analysis of the dependability and trustworthiness aspects of SNNs and neuromorphic hardware. It outlines potential mitigation and countermeasure strategies to improve the reliability, testability, and security aspects of SNN hardware and ensure its trustworthy deployment in critical application domains.</div
Clinical and metabolic phenotyping of continuous versus intermittent ENteral NUTrition in ventilated adults with shock: ENNUT trial protocol
No full textInternational audienceIntroduction Critically ill patients often require enteral nutrition, but the optimal feeding strategy—continuous or intermittent—remains uncertain. While continuous enteral nutrition ensures steady nutrient delivery, it may inhibit key metabolic and cellular processes such as autophagy and ketogenesis. Intermittent enteral nutrition, by mimicking fasting periods, could activate protective pathways, potentially improving clinical outcomes. However, evidence for its efficacy and safety in intensive care units (ICUs) is limited. This study evaluates the clinical and metabolic impacts of fasting intervals during intermittent enteral nutrition compared with continuous enteral nutrition in critically ill patients. Methods and analysis We designed a multicenter, randomised, open-label trial across nine French ICUs, enrolling adult patients requiring mechanical ventilation and vasopressor support. Participants will receive either intermittent or continuous enteral nutrition for 7 days, with the primary endpoint being the change in the Sequential Organ Failure Assessment (SOFA) score from Day 1 to Day 7 or ICU discharge. Secondary endpoints include nutritional intake, metabolic markers, gastrointestinal tolerance, ICU-acquired infections and mortality rates. Quality of life will be assessed at discharge. A total of 174 patients will be included. Descriptive statistics will summarise group characteristics, with the Student’s t-test or the Mann-Whitney U test depending on data distribution for SOFA score change, and regression for confounders. Secondary endpoints will be analysed using regression, χ 2 or Fisher’s exact test, as appropriate. Ethics and dissemination The study protocol was approved by a French ethics committee on 24 October 2023 (Comité de Protection des Personnes Ile de France 1, Paris, France, number SI 23.03427.000435). Patients are included after providing informed consent. Results will be submitted for publication in a peer-reviewed journal. Trial registration number Registered on clinicaltrials.gov on 26 March 2023 ( NCT06330610 )
Enhancement of heat transfer using Faraday instability
No full textInternational audienceThis study explores the Faraday instability as a mechanism to enhance heat transfer in two-phase systems by exciting interfacial waves through resonance. The approach is particularly applicable to reduced-gravity environments where buoyancy-driven convection is ineffective. A reduced-order model, based on a weighted residual integral boundary layer method, is used to predict interfacial dynamics and heat flux under vertical oscillations with a stabilising thermal gradient. The model employs long-wave and one-way coupling approximations to simplify the governing equations. Linear stability theory informs the oscillation parameters for subsequent nonlinear simulations, which are then qualitatively compared against experiments conducted under Earth’s gravity. Experimental results show up to a 4.5-fold enhancement in heat transfer over pure conduction. Key findings include: (i) reduced gravity lowers interfacial stability, promoting mixing and heat transfer; and (ii) oscillation-induced instability significantly improves heat transport under Earth’s gravity. Theoretical predictions qualitatively validate experimental trends in wavelength-dependent enhancement of heat transfer. Quantitative discrepancies between model and experiment are rationalised by model assumptions, such as neglecting higher-order inertial terms, idealised boundary conditions, and simplified interface dynamics. These limitations lead to underprediction of interface deflection and heat flux. Nevertheless, the study underscores the value of Faraday instability as a means to boost heat transfer in reduced gravity, with implications for thermal management in space applications
Animal culture
No full textInternational audienceThe concept of culture, once viewed as a uniquely human trait, is now accepted to occur widely across the animal kingdom. Beginning with the groundbreaking discoveries of Japanese macaques and their innovative behaviors of potato washing, flavoring, wheat placer mining, and others, we explore the breadth of animal culture across primates, cetaceans, birds, and even insects. The chapter delves into the mechanisms of cultural transmission, such as social learning and social facilitation, and distinguishes between preculture, protoculture, and culture. It also highlights the role of cumulative culture in shaping complex behaviors, the interplay of co-culture in interspecies interactions, and the implications for conservation efforts
Far-right vote in the 2024 European and Legislative elections in France: same old, same old ?
No full textInternational audienc
Euclid: Relativistic effects in the dipole of the 2-point correlation function
No full textInternational audienceGravitational redshift and Doppler effects give rise to an antisymmetric component of the galaxy correlation function when cross-correlating two galaxy populations or two different tracers. In this paper, we assess the detectability of these effects in the Euclid spectroscopic galaxy survey. We model the impact of gravitational redshift on the observed redshift of galaxies in the Flagship mock catalogue using a Navarro-Frenk-White profile for the host haloes. We isolate these relativistic effects, largely subdominant in the standard analysis, by splitting the galaxy catalogue into two populations of faint and bright objects and estimating the dipole of their cross-correlation in four redshift bins. In the simulated catalogue, we detect the dipole signal on scales below , with detection significances of and in the two lowest redshift bins, respectively. At higher redshifts, the detection significance drops below . Overall, we estimate the total detection significance in the Euclid spectroscopic sample to be approximately . We find that on small scales, the major contribution to the signal comes from the nonlinear gravitational potential. Our study on the Flagship mock catalogue shows that this observable can be detected in Euclid Data Release 2 and beyond