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Pea breeding strategies for the agroecological and food transitions
No full textoral, keynote speakerInternational audienc
Représentations de la RSO, capital marque et comportements des supporters
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Combined effects of parasitism and anthropogenic stressors on behaviour and biomarkers in the freshwater amphipod Gammarus fossarum: dominant and additive effects prevail.
No full textInternational audienceChemical contaminants, elevated temperature, and parasitism are expected to impose multiple stresses on aquatic organisms. Their sublethal effects on fitness may be mediated through multiple traits, and combine in additive or interactive ways. In freshwater ecosystems, at least half of paired-stressor effects are either additive or antagonistic, but few studies have considered parasitism. Using a fully crossed factorial design, we investigated survival, behaviour, and biomarker responses of the amphipod Gammarus fossarum to four-day exposure methomyl insecticide, in interaction with temperature and parasitic infection. Infection with the acanthocephalan Pomphorhynchus tereticollis was taken into account at two levels, (i) the population level, comparing uninfected gammarids from “non-naïve” populations hosting the parasite to ones from “naïve” populations; (ii) at the individual level, comparing infected and uninfected gammarids from non-naïve populations. Overall, methomyl and temperature alone had limited effect, while parasitism had pervasive effects on most traits, including redox status and defensive systems. At the population level, the combined effects of infection and of either methomyl or elevated temperature were additive (survival, feeding rate, locomotion, acetylcholinesterase, antioxidant), or antagonistic (survival, feeding rate, locomotion), when not dominant. At the individual level, most combined effects of infection and either temperature or methomyl were dominant. We thereby provide evidence for mainly dominant and additive effects of parasitism combined with methomyl or elevated temperature. Their physiological and environmental drivers remain to be investigated. Given the pervasive effects of parasitism, alone or combined with other stressors, parasitism should be taken into account to gain realism in ecotoxicological studies
Un nouvel indicateur de pollinisation fondé sur les données de rendement des cultures, déployable de la parcelle à la France entière
No full textInternational audienceMise en place d'un indicateur simple qui semble renseigner sur l'efficacité de la pollinisatio
Effect of Laser Treatment on the High-Temperature Oxidation of TitaniumAlloys Through Surface Nitrogen Enhancement
No full textInternational audienceHigh-temperature corrosion of Ti-based alloys remains a challenge in applications operated above 600°C. Recent experimental studies have shown that atmospheric nitrogen significantly influences theoxidation of Ti and its alloys in an air atmosphere [1-3], with a synergistic interaction between nitrogenand alloying elements [1,2]. The interaction of nitrogen with alloying elements contributes to theformation of a compact oxide scale and reduces the mass gain during high-temperature tests.Therefore, this work's main aim is to intentionally introduce nitrogen into the surface region of thenear-α Ti alloy using laser surface treatment (LST) and to evaluate its resistance to high-temperatureoxidation. LSTs were performed using the Brilliant laser (nanosecond, 1064 nm) on the multi-component Ti-alloy Timetal 834 (Ti-Al-Sn-Zr-Nb-Mo-Si-C). Treatments were performed in the airatmosphere with varying laser settings to modify the nitrogen content in the surface layer, producingsamples with distinct surface colors, including yellow, purple, and blue. Oxidation tests at 650 °C for100 hours in an air atmosphere revealed a significant improvement in the high-temperature oxidationresistance of LST-treated samples. To explain the observed phenomenon, the modified Ti834 samples(both unoxidized and oxidized) were analyzed in terms of morphology, roughness, chemicalcomposition, and phase composition. Particular emphasis was placed on examining the microstructureand chemical composition of cross-sections after laser treatment.A systematic comparison of surface conditions after LST and their oxidation resistance enabled theidentification of key factors responsible for enhancing high-temperature oxidation resistance. LSTmodification, through microstructure refinement and presence of the nitrogen in the surface region,causes changes in the oxidation behavior of Ti834 alloy.These findings are especially significant as they can facilitate the development of surface treatmentstailored for applications in the aerospace, automotive, and gas turbine industries.This research was financially supported by The National Science Center Poland under Grant SonatinaNo. 2023/48/C/ST11/00265[1] T.C. Valenza, P.K. Weber, E.A. Marquis, Corros Sci 235 (2024).[2] V. Optasanu, P. Berger, B. Vincent, M.C. Marco de Lucas, F. Herbst, T. Montesin, L. Lavisse, CorrosSci 224 (2023) 111547.[3] C. Dupressoire, M. Descoins, A. Vande Put, E. Epifano, D. Mangelinck, P. Emile, D. Monceau, ActaMater 216 (2021) 117134
Wetting properties of titanium surfaces tuned by duplex treatments combining nanosecond laser treatment and chemical functionalization
No full textInternational audienceDuplex treatments combining different processing methods open up a wide range of possibilities formodifying the surface properties of materials. In the case of titanium, nanosecond laser treatmentshave demonstrated their ability to induce a surface oxidation layer whose stoichiometry and propertiesdepend on treatment conditions [1-2]. The covalent grafting of organic molecules onto the surface oftitanium oxide films [3-4] opens up interesting prospects for controlling the hydrophobicity andbiocompatibility of titanium surfaces, as well as for developing self-cleaning surfaces, sensors,photocatalytic supports, etc. [3].The aim of the present work is to tune the wetting properties of metallic titanium by laser-assistedsurface oxidation followed by chemical functionalization to produce hydrophobic to superhydrophobicsurfaces.A Q-switched and frequency-doubled Nd:YAG green laser (KALUTI) operating at 532 nm and delivering5 ns pulse duration was used for laser treatments on CP-Ti plates. They produced a saw-toothpatterned surface covered by an oxidized surface layer containing mainly TiO2-anatase [5]. Thechemical modification of laser-treated surfaces with octylphosphonic acid (OPA) in form oftetrahydrofuran (THF) or boiling water solutions was performed. The effect of concentrations ofmodifier going from 0.01 to 100 mM on the resulting organic load, layer structure and contact angleswas investigated. The duplex-treated surfaces were characterized by SEM-EDS/WDS, XPS, XRD andRaman spectroscopy.OPA solutions in THF were found to give rise exclusively to monolayer formation (16 ± 5 Å), with surfacecoverage completed at a phosphorus concentration of around 4.8 at.% according to XPS results.Concentrated OPA solutions in water produced an additional layer of titanium (IV) octylphosphonate,bringing the total thickness of the organic layer to 37 ± 11 Å at a maximum phosphorus concentrationof approx. 8 at.%.Despite the different nature of the organic layers, all surfaces containing at least 2.2 at.% P showed asimilar static contact angle of around 155°. Based on dynamic contact angle measurements,superhydrophobic behavior was confirmed for surfaces bearing a full OPA monolayer and titaniumphosphonate (IV) overlays.[1] F. Torrent et al., Surf. Coat. Technol. 255 (2014) 146–152[2] Z. Liu et al., Biosurf. Biotribol., 8(2022) 95–120[3] L. D. Trino et al., Colloids and Surfaces A 546 (2018) 168–178[4] I. Tomashchuk et al., Appl. Surf. Sci. 609 (2023) 155390[5] N. Zaitseva et al. , Adv. Eng. Mater. (2024) 2401046
The role of the motor system in action imagination and comprehension
No full textInternational audienceCovert actions encompass cognitive processes such as motor imagery, action observation, and action language. These processes ignite motor simulations within the mind and engage neural circuits underlying sensorimotor functions, offering promising potential for optimizing motor performance and rehabilitation strategies. Yet, despite broad consensus on the motor system’s involvement, its precise role — whether a dynamic embodiment mechanism or a mere epiphenomenon — remains a matter of intense debate. In this review, we present a comprehensive analysis of motor system engagement across motor imagery, action observation, and action language. First, we examine correlational evidence derived from functional magnetic resonance imaging and transcranial magnetic stimulation studies in healthy individuals, including those with impaired mental simulation abilities. This evidence helps elucidate whether, and to what extent, these cognitive processes recruit the motor system, particularly the primary motor cortex. We then turn to causal evidence, which allows us to infer the functional role of the motor system in these processes. Specifically, we review findings from studies investigating behavioral changes, patients with lesions, and artificial lesions in healthy participants created using neuromodulation techniques. By integrating these perspectives, we seek to clarify this ongoing debate by illuminating the functional role of the motor system in motor imagery, action observation, and action language
La captation audiovisuelle pour saisir un processus de recherche création sur l'engagement étudiant : apports et spécificités
No full textInternational audienc
Study of the tribological behavior of SnO2 coatings under low atmospheric ethanol contamination
No full textInternational audienceFriction and wear at the interface between solids have a major impact on the service life of all kinds ofmechanical systems. The development of high-performance dry lubricants to deal with this problemmust take into account the surrounding atmosphere, including the presence of contaminants. Differentphysico-chemical mechanisms involving the materials in contact and their internal and external(ambient) contaminants can compete and give rise to the formation of lubricating interfaces throughmechanically activated chemical reactions involving particles generated at the contact [1-2]. Traces ofcontaminants (in the ppm or ppb range) are enough to initiate the creation and maintenance of thislubricating and anti-wear interface [3,4].The aim of the present work is to investigate the influence of very low concentration of volatilecompounds, at ppm level, on the tribological behavior of surface coatings. To this end, tin oxide, knownfor its sensitivity to the adsorption of ethanol molecules, was chosen as the material to study. Indeed,SnO2 is used as a sensitive material for ethanol gas sensors.PVD-deposited SnO2 thin films on silicon substrates were subjected to friction in three differentatmospheres: laboratory air, dry N2 and dry N2 contaminated with 1000 ppm ethanol vapor. Contactconditions: sliding speed 8 mm/s, average contact pressure 330 MPa, room temperature, 100Cr6sliding counterpart and 500 reciprocating friction cycles.The results showed a strong impact of the gaseous environment on the coefficient of friction, as wellas on damage and wear. This effect, expected for N2 compared with laboratory air, was also observedin the case of N2 contamination with traces of ethanol, with a reduction in average friction by a factorof 2.5 to 3, and much lower friction damage.The study of friction tracks on SnO2 films and steel counterparts using surface analysis techniques isessential to advance our understanding of the tribochemical mechanisms involved. Here, SEMobservation of friction scars and elemental EDX analysis have been complemented by XPS, SIMS andmicro-Raman spectroscopy. Surface analysis shows that material composition at the interfaces varies,particularly in terms of the proportion of iron oxides. The formation of a mixed Fe-Sn-O compound hasalso been investigated.[1] G. Colas et al., Tribol. Int. 65 (2013) 177–189[2] X. Chen et al, ACS Appl. Mater. Interfaces 6 (2014) 13389–13405[3] N. Argibay et al., Carbon 138 (2018) 61–68[4] Y. Huang et al., Surf. Coat. Technol. 383 (2020) 12527