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Mixed Ni/Cu-sandwich dawson polyoxotungstates: Electrochemistry and DFT insights
No full textInternational audienceGiven the established electrocatalytic potential of Ni(II)-and Cu(II)-containing tungsten-based POMs, the primary objective of this work was to create a unique molecular architecture combining both active metal centres in the two Dawson sandwich POMs, [(CuOH 2 ) 2 Ni 2 (As 2 W 15 O 56 ) 2 ] 16-and [(NiOH 2 ) 2 Cu 2 (As 2 W 15 O 56 ) 2 ] 16-. This aims to exploit potential synergistic effects for enhanced catalytic performance and to deepen the understanding of redox mechanisms in these mixed-metal systems. A detailed electrochemical study of the two POMs in solution, compared to their homometallic analogues containing only Ni(II) or only Cu(II) centres, was conducted using cyclic voltammetry (CV), also coupled to quartz crystal microbalance in order to monitor Cu deposition/ desorption phenomena, and controlled potential coulometry, enabling unambiguous identification and differentiation. X-ray photoelectron spectroscopy (XPS) unequivocally corroborated these findings. Furthermore, density functional theory (DFT) calculations provide additional insights that are relevant to rationalise the electrochemical measurements. The molecular orbital sequence, energies and shapes provide relevant supporting information to the experimental facts. Combined evidence establishes that Na/Ni compounds maintain the Wonly electrochemical fingerprint, whereas new CV features appear when Cu(II) is part of the structure, modulated by the rest of the equatorial composition. Protonation has been explored and its effects on the redox chemistry examined at the theoretical level
Middle Eocene hyperthermal seasonality from Paris Basin marine mollusks
No full textInternational audienceThe Earth has experienced hyperthermal events in the past, characterized by maximum durations of hundreds thousand years, significant magnitude, global extent, and drivers associated with increases in greenhouse gas concentrations, therefore making them potential analogues for current climate change. The Middle Eocene Climatic Optimum (MECO) that occurred 40 Ma ago, is marked by a CO2-driven global warming of +4 to +6° C, affecting global temperatures. Here, we present a detailed reconstruction of seasonal fluctuations in seawater temperatures during this warming event in littoral environment, based on geochemical analyses (δ18O and Δ47) of shallow-marine mollusks from the Paris Basin. Our data show a stability in mean winter temperatures compared to pre-MECO conditions, but a marked warming of +10°C in maximum estuarine water temperatures, with a seasonal temperature range increasing from 12°C before the MECO to 22°C at the climax of the event. We demonstrate that at mid-latitudes, annual maximum shallow-water temperatures increased from 30 ± 2°C before the event to a maximum of 41 ± 4°C at the warming peak. This pattern is associated with a seasonal regime characterized by dry summers and wet winters, implying that the Paris Basin experienced a super-hot summer Mediterranean climate during the MECO
Bénéfices des aliments fermentés, de l’empirisme aux démonstrations scientifiques : l’apport de Ferments du Futur
No full textInternational audienceFermentation has held a central place in human nutrition for millennia, both for the preservation of perishable goods and for their transformation. Fermented foods indeed have unique sensory properties, in addition to health benefits that are increasingly well-documented. Furthermore, fermentation contributes to the sustainability of our food systems. As we move towards more natural, healthy and sustainable diets, fermentation represents a key technology for transforming agri-food systems. The Ferments du Futur (FdF) initiative, led by INRAE and ANIA with the support of France 2030, aims to develop new ferments, to improve fermentation processes and to create high added-value fermented foods, drawing on biotechnologies, data science and public–private collaborations. This article outlines the major benefits associated with fermentation: food safety, sensory properties, nutrition and health and environmental impact, while highlighting the concrete solutions that FdF will provide, through its projects and technological platforms.La fermentation occupe une place centrale dans l’alimentation humaine depuis des millénaires, pour la conservation des denrées périssables mais aussi pour leur transformation. Les aliments fermentés ont en effet des propriétés sensorielles uniques, auxquelles s’ajoute un bénéfice santé de mieux en mieux documenté. La fermentation contribue par ailleurs à la durabilité de nos systèmes alimentaires. Dans un contexte de transition vers une alimentation plus naturelle, plus saine et plus durable, la fermentation émerge comme une solution innovante pour transformer les systèmes agroalimentaires. L’initiative Ferments du Futur (FdF), portée par INRAE et l’ANIA dans le cadre de France 2030, vise à développer de nouveaux ferments, améliorer les procédés de fermentation et créer des aliments fermentés à haute valeur ajoutée, en s’appuyant sur les biotechnologies, les sciences des données et un dialogue poussé entre acteurs publics et privés. Cet article présente les grands enjeux associés à la fermentation : sécurité des aliments, propriétés sensorielles, nutrition et santé, impact environnemental, tout en illustrant les solutions concrètes qu’apportera FdF, notamment via ses projets et plateformes technologiques
Method: Modelling resource acquisition and allocation – extension and calibration of a cow model to a sheep
No full textInternational audienceSimulation models are suitable to investigate how complex systems respond to changes. This is of particular interest regarding animal feed efficiency as this trait must be evaluated throughout the entire lifetime and thus is affected by trade-offs between physiological functions. The aim was to extend and calibrate the dynamic, mechanistic simulation model “Acquisition and Allocation” (AQAL) from dairy cows to reproductive ewes. This model was originally developed for investigating the effects of resource acquisition and allocation potentials on feed efficiency but also allows investigation of trade-offs between life functions. The model represents an individual female from birth to death or herd exit and uses four input parameters to describe the resource acquisition ability and allocation potential. The obtained energy is split between life functions such as maintenance, growth, reproduction and lactation. By including reproductive management rules, it allows for shifts between physiological stages, which then feedback and affect the current acquisition ability and resource allocation. To adapt the model to a reproductive ewe, we have included a litter size effect, an acquisition capacity linked to gestation, and a seasonal conception probability. The litter size is influenced by the proportion of fat in empty body weight at conception, and it affects the acquisition linked to gestation, the allocation to gestation and the allocation to lactation. We also incorporated the energetic costs of the gravid uterus depending on litter size. We use three different acquisition-allocation profiles to test the consistency of the litter size effect. We show that the model simulates consistent lifetime trajectories of reproductive ewes and that the effect of litter size adequately reflects the demands of increased litter size within the different acquisition/allocation profiles
N-Cadherin/α-Catenin Drive Adhesion and Actin Regulation to Orchestrate Tunneling Nanotube Formation
No full textAbstract Cell-to-cell communication is essential for maintaining homeostasis in multicellular organisms. Tunneling nanotubes (TNTs)—actin-based membranous connections—mediate the exchange of diverse cargoes between distant cells. Unlike other cellular protrusions, TNTs exhibit unique ultrastructural features and are enriched in the adhesion molecule N-Cadherin. Here, we dissect the role of N-Cadherin in the formation and function of TNTs in SH-SY5Y human neuronal-like cells. We show that N-Cadherin, via its effectors α-Catenin and p120-Catenin, is a central regulator of TNT architecture and their cargo transfer capability. Regulators of cortical tension p120-Catenin, ROCK, and non-muscle myosin II also emerge as critical for TNT functionality, highlighting a mechanosensitive component to TNT regulation. Moreover, we reveal that NMIIA can be processive inside TNTs and transfer through them using actin’s retrograde flow. Finally, we identify the Cdc42–IRSp53–N-WASP pathway as a downstream effector axis enhancing intercellular transfer downstream of N-Cadherin. Together, our findings uncover a structural and functional link between N-Cadherin signaling and TNT-mediated intercellular communication
Probing millisecond magnetar formation in binary neutron star mergers through X-ray follow-up of gravitational wave alerts
No full textInternational audienceThe nature of the remnant of a binary neutron star (BNS) merger is uncertain. Though certainly a black hole (BH) in the cases of the most massive BNSs, X-ray lightcurves from gamma-ray burst (GRB) afterglows suggest a neutron star (NS) as a viable candidate for both the merger remnant as well as the central engine of these transients. When jointly observed with gravitational waves (GWs), X-ray lightcurves from BNS merger events could provide critical constraints on the remnant's nature. We aim to assess the current and future capabilities to detect a NS remnant through X-ray observations following GW detections. To this end, we simulate GW signals from BNS mergers and the subsequent X-ray emission from newborn millisecond magnetars. The GW detectability is modeled for both current and next-generation interferometers, while the X-ray emission is reproduced using a dedicated numerical code that models magnetar spin-down and ejecta dynamics informed by numerical-relativity simulations. In our simulations, 2% - 16% of BNS mergers form millisecond magnetars. Among these, up to 70% could be detectable, amounting to up to 1 millisecond magnetar detection per year with SVOM/MXT-like instruments during the LIGO Virgo KAGRA LIGO India (LVKI) O5 run, with optimal detectability occurring about 2 hours post-merger. For next-generation GW interferometers, this rate could increase by up to three orders of magnitude, with peak detectability 3 to 4 hours post-merger. We also explore how the magnetar's magnetic field strength and observer viewing angle affect detectability and discuss optimized observational strategies. Although more likely with upcoming GW interferometers, detecting the spin-down emission of a millisecond magnetar may already be within reach, warranting sustained theoretical and observational efforts given the profound implications for mergers, GRBs, and NS physics of a single detection
Bulletin de veille du réseau d'écotoxicologie terrestre et aquatique N°79
No full textINRAE, réseau ECOTOX → A paraîtreBulletin de veill
Competing effects of charge-carrier and impurity scattering limiting phonon heat conduction in heavily-doped silicon
No full textWith respect to undoped semiconductors, thermal transport by phonons is limited by two additional mechanisms when doping increases: charge-carrier and impurity scattering. Previous works provided contradicting conclusions on the dominant doping-induced scattering mechanism in silicon. In this work, we clarify the competing roles of impurity and charge-carrier scatterings of phonons in the reduction of the lattice thermal conductivity in n-and p-doped silicon, by comparing experimental results obtained with the 3ω method and predictive DFT-based calculations for a large set of doping concentrations and a wide temperature range. The analysis allows delimiting the doping and temperature ranges where (i) extrinsic scattering surpasses intrinsic (phonon-phonon and phonon-isotope) one and (ii) one of the two doping-induced mechanisms plays the dominant role. We observe that the experimental setup impacts both the thermal conductivity value and the critical doping concentration at which the thermal conductivity is reduced by half
Characterising the properties of the atmospheric emission at Teide Observatory in the 10-20 GHz range with QUIJOTE data
No full textInternational audienceQUIJOTE is a CMB experiment composed of two telescopes, QT1 and QT2, located at the Teide Observatory in Tenerife, Spain. The MFI instrument (2012-2018), installed on QT1, observed the sky at four frequency bands (11, 13, 17, and 19 GHz) with one degree angular resolution. Its successor, MFI2, began operations in 2024 and operates in the same bands. This paper has two main goals: first, to characterise the atmospheric conditions at Teide Observatory to improve existing models at these frequencies, and second, to empirically characterise atmospheric turbulence using QUIJOTE MFI and MFI2 observations. This work has implications for both atmospheric physics and CMB studies and can support future reanalyses of MFI data or the preparation of upcoming instruments such as the Tenerife Microwave Spectrometer. We used data from GPS antennas, the STELLA observatory, and radio soundings to derive median profiles and distributions of key atmospheric parameters for 2012-2018. MFI data were analysed to compute atmospheric structure functions at 17 and 19 GHz and to study the correlation properties of the atmospheric signal through cross-correlation between horns at the same frequency. MFI2 observations were used to estimate the atmospheric power spectrum and compare it with the structure function derived from MFI data. The water vapour density profile follows an exponential decay with a characteristic half-height of about 1000 m. Median PWV in 2012-2018 is 3.3 mm. For high PWV conditions, the structure function agrees with the Kolmogorov turbulence model. The slope of the power spectrum also matches the model prediction, within the frequency range limited by the outer scale and instrument noise. Finally, from the correlation function, we find that atmospheric conditions remain stable for about 1-2 hours
Clustering redshift distribution calibration of weak lensing surveys using the DESI-DR1 spectroscopic dataset
No full textInternational audienceWe estimate the source redshift distribution of current weak lensing surveys by applying the clustering-based redshift calibration technique, using the galaxy redshift sample provided by the Dark Energy Spectroscopic Instrument Data Release 1 (DESI-DR1). We cross-correlate the Bright Galaxy Survey (BGS), Luminous Red Galaxies (LRGs) and Emission Line Galaxies (ELGs) from DESI, within the redshift range , with overlapping tomographic source samples from the Dark Energy Survey (DES), Kilo-Degree Survey (KiDS), and Hyper Suprime-Cam (HSC) survey. Using realistic mock catalogues, we test the stability of the clustering-redshift signal to fitting scale, reference-sample choice, and the evolution of source galaxy bias, and we explicitly model and marginalise over magnification contributions, which become non-negligible at due to the depth of the DESI ELG sample. We then compare the resulting bias-weighted redshift distributions to those calibrated using self-organising map (SOM) techniques, finding agreement within uncertainties for all surveys and tomographic bins. Our results demonstrate that clustering redshifts enabled by DESI's unprecedented spectroscopic sample provides a robust, complementary, and independent constraint capable of reducing one of the dominant systematic uncertainties in weak lensing cosmology