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Improvement in mechanical as well as magnetic properties of a (FeCoNi)<sub>90</sub>Ti<sub>10-x</sub>Al<sub>x</sub> complex concentrated alloy series by tuning the chemical order
No full textInternational audienceThere is considerable interest in magnetic materials which also possess good mechanical properties. Hence, the effect of Ti/Al ratio on the microstructure, mechanical and magnetic properties of (FeCoNi)90Ti10-xAlx complex concentrated alloys (CCA) was investigated. An increase in the Ti/Al ratio in these CCA enhanced chemical ordering and substantially improved selected mechanical and magnetic properties. As the Ti/Al ratio changed from 10 to 0, the ductility increased from 7.5 to close to 50 %, the saturation magnetization (Ms) increased from 115.2 to 136.7 emu/g, and the coercivity (Hc) decreased from 17.9 to 4.2 Oe. The Fe30Co30Ni30Ti5Al5 alloy exhibit higher UTS×EL value than available soft magnetic materials and has relatively higher and lower compared with other CCA. These results provide a methodology to modulate the chemical order in the Fe-Co-Ni system by Al and Ti additions and synergistically tune the mechanical and magnetic properties for high performance rotating electrical machine applications
Large area junctions of self-assembled monolayers of functional coordination compounds on metallic substrates
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Rencontre autour de la mémoire : pré-actes
No full textInternational audienceLa plupart des sociétés humaines, passées comme actuelles, ont répondu et répondent au décès de leurs membres par la mise en oeuvre, le plus souvent à court terme, de rites de séparation destinés à marquer l’intégration du défunt au monde des morts. Cette séparation, aux dimensions tant symboliques (passage vers l’au-delà) que physiques (mise à distance, voire destruction du cadavre), ne signe cependant que rarement la disparition du lien unissant les vivants à leurs morts, les premiers conservant le souvenir des seconds et pouvant, dans bien des cas, en entretenir la mémoire bien après le temps des funérailles. Cette mémoire, qui s’exprime à différentes échelles – celle de l’individu, de la famille, du groupe –, peut prendre des formes multiples et s’appuyer sur une grande variété de supports. Immatérielle par essence, elle peut parfois s’ancrer matériellement dans un lieu ou un objet. Dépendante des vivants qui la perpétuent, elle s’avère bien souvent mouvante au fil des ans et contrainte en termes de temporalité. Elle peut, en outre, ne pas viser au seul souvenir du défunt et refléter des contextes et enjeux sociétaux lui donnant cadre, sa mise en oeuvre confinant par exemple dans certaines sociétés à la recherche d’une sorte de transcendance de la mort, servant dans d’autres des desseins idéologiques ou politiques.Riche d’enseignements sur les sociétés passées et actuelles, la question de la mémoire des défunts et de son négatif, l’oubli, sera au coeur de la 16e Rencontre du Gaaf. À vocation internationale et pluridisciplinaire, ce colloque se veut être un lieu d’échanges entre chercheurs issus d’horizons divers, invitant les contributions d’archéologues et anthropologues travaillant sur des contextes chrono-géographiques variés, ainsi que d’acteurs d’autres disciplines des sciences sociales (p. ex. historiens, sociologues, ethnologues). Les discussions scientifiques s’articuleront autour de quatre grandes thématiques. Deux d’entre elles aborderont respectivement la question de la matérialité et de la temporalité de la mémoire, en s’intéressant à ses supports physiques (monuments, épitaphes, sources textuelles et iconographie, etc.) et aux différents temps funéraires (lesquels diffèrent selon que l’on aborde la question du côté biologique, du côté social ou du côté idéel). Un troisième thème s’attachera à discuter les ressorts et motivations de la construction, voire de la reconstruction, de la mémoire. Enfin, un dernier thème abordera la problématique selon un angle de vue antagonique, en considérant la dépréciation, la privation ou la négation de cette mémoire, et l’invisibilisation de certains morts ou de certains groupes qui en résulte dans différents contextes
Directional light scattering in Mie-resonant Si particles with ultra-thin plasmonic shells
No full textInternational audienceWe present the synthesis and characterization of Au-decorated Si core-shells as candidate meta-atoms. We found a damped magnetic dipole (MD) for smaller Si cores (100 – 130 nm) and an enhanced MD for larger cores (150 – 200 nm). Continuous plasmonic shells of ~12 nm are needed to significantly improve forward scattering.Subwavelength-sized Si particles interact strongly with visible (vis) and near-infrared (NIR) light to produce strong electric and magnetic resonances. These can combine to produce interesting optical effects, such as pure forward scattering. A requirement for this to occur efficiently is that the electric dipole (ED) and magnetic dipole (MD) modes must be of similar amplitude and phase. At wavelengths where this occurs, the particles act analogously to the forward-propagating point sources of light used in Huygens’ constructions. This directional scattered light has a range of potential applications in the creation of metamaterials.We have investigated dielectric@metal core-shell architectures comprised of both resonant cores and resonant shells as candidate particles in which the spectral overlap of the electric and magnetic dipoles might be controlled to create strong directional scattering. There are currently two reports of the synthesis and characterization of Au shells around Si cores, both thicker than desirable. [1,2] Chaâbani et al. presented Si@Au particles, with non-uniform shells composed of Au particle diameters between 10 and 25 nm, which presented enhanced electric field and Fano-resonances due to the coupling of the Mie modes of the Si core and the localized surface plasmon resonance (LSPR) of the Au shell. [1] Sugimoto et al. similarly presented Si@Au particles with a rough ~25 nm Au shell. [2] In both of these reports of Si@Au core-shell particles, the experimental data could not be accurately fit by simulations due to non-spherical cores and inhomogeneous shells. Ultrathin and homogeneous coatings have not yet been achieved around spherical Si particles.In this study, we present a two-step aqueous approach to prepare Si@Au core-shell particles with controllable shell thickness below 10 nm. The Au nanoparticle (AuNP) density around the Si particles can be increased by performing a second functionalization/deposition step. We studied the electromagnetic response of the particles using single-particle scatter spectroscopy and electron energy loss spectroscopy (EELS). Our results were compared with reference Si spheres and SiO2@Au core-shell particles, to allow us to establish the contribution from the Au decoration to the optical response of the hybrid particles. To further elucidate the nature of the electromagnetic response of the particles, these observations were supported by T-matrix simulations which replicated our experimental findings, and showed the importance of controlling the shell/core dimensions and the need for a continuous shell to maximize forward scattering. We found that continuous plasmonic shells of ~12 nm thickness are needed to significantly improve forward scattering intensity.References1.Chaâbani, W, J Proust, S Ouellet, A Movsesyan, J Béal, R Bachelot, T Xu, A L Baudrion, PA Adam, D Boudreau, A Chehaidar, and J Plain, “Si@Au core–shell nanostructures: Toward a new platform for controlling optical properties at the nanoscale.” J Phys Chem C, Vol. 125, 20606. 2021. DOI: 10.1021/acs.jpcc.1c061822.Sugimoto, H., T Hinamoto, Y Kazuoka, A Assadillayev, S Raza, and M Fujii. “Mode hybridization in silicon core–gold shell nanosphere.” Small Vol. 18, 2204890, 2022. DOI: 10.1002/smll.20220489
Synthesis of Si@Au core-shell particles for directional light scattering
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Ti doped LSCF for improvement of Solid Oxide Cell long term stability operated on SOEC condition
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CABiosE: Comparative Analyses of Biostimulants effects on tomato crop and their associated microbiots under water stress conditions
No full textInternational audienceThe CABiosE project studies the effects of biostimulants (BS) on tomato crops and their microbiota under water stress conditions. BS enhance plant development by improving nutrient assimilation or tolerance to abiotic stress. The goal is to determine whether their effects are direct on plants or indirect via the microbiota. The study includes three phases: selecting 2 BS out of 7 (2024-2025), deeper analysis on young plants and fruits (2025-2026), and testing under production conditions. Preliminary results show that water stress reduces plant dry weight, and BS effects on growth and yield vary, with modalities 6 and 7 selected for further trials. The project aims to optimize BS use to enhance crop resilience to water stress, provide recommendations to farmers, and develop innovative tools to assess BS effectiveness.
On the cohomological representations of finite automorphism groups of singular curves and compact complex spaces
No full textLet G be a finite group acting tamely on a proper reduced curve C over an algebraically closed field. We study the G-module structure on the cohomology groups of a G-equivariant locally free sheaf F on C, and give formulas of Chevalley--Weil type, with values in the Grothendieck ring R_k(G)_Q of finitely generated G-modules. We also give a similar formula for the singular cohomology of compact complex spaces. The focus is on the case where C is nodal. Using the Chevalley--Weil formula, we compute the G-invariant part of the global sections of the pluricanonical bundle ω_C^{\otimes m}. In turn, we use the formula for m=2 to compute the equivariant deformation space of a stable G-curve C. We also obtain numerical criteria for the presence of any given irreducible representation in space of the global sections of ω_C\otimes F, where F is an ample locally free G-sheaf on C. Some new phenomena, pathological compared to the smooth curve case, are discussed
MSpangepop: Simulating complex structural variants under advanced demographic scenarios using the coalescent
No full textInternational audienceBackgroundStructural variants (SVs) — large genomic changes such as insertions, deletions and inversions —are known to significantly contribute to genetic variation. Despite their impact on phenotypic diver-sity and adaptation, they remain relatively understudied [1]. The recent emergence of variationgraphs provides an efficient way to integrate these large variants in population and pangenomestudies, capturing the full genomic landscape of genes within clades.Simulating genomes is essential for evaluating analytical methods and improving genetic studies byproviding controlled datasets for testing hypotheses. Although several programs exist to simulateSVs genome-wide (e.g. [2]), none are able to account for complex evolutionary scenarios such asspeciation events, resulting in unrealistic star-like locus genealogies. On the other hand, coalescent-based simulators such as MSprime [3], which can simulate a wide variety of ancestry and demo-graphic models, do not currently support the simulation of large and complex SVs.ResultsTo fill this gap and allow biologists to directly produce simulated variation graphs, we developMSpangepop, a Python-based simulation workflow inspired by VISOR [2] and managed by Snake-make [4]. Starting with a reference sequence and a demographic scenario, MSprime [3] simulatesthe coalescent of each locus (i.e. recombination block) of the genome. Each coalescent tree is thentraversed lineage by lineage in order to chronologically map SVs simulated from a large panel ofclasses, allowing for complex nested variants. A coalescent-aware variation graph is thus progres-sively constructed and written to a Graphical Fragment Assembly file (GFA). For greater flexibility,genome sequences and alignments can also be generated directly as FASTA files.ConclusionMSpangepop allows biologists to simulate variation graphs under realistic demographic models for avariety of purposes, including benchmarking and simulation-based inferences. Future developmentsinclude the simulation of transposable elements and the modulation of the mutational landscape toaccount for genomic features like ORFs
