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Efficient and selective seawater oxidation by manganese ferrite electrocatalysts obtained via a vapor phase strategy
No full textInternational audienceElectrolysis of seawater is an appealing route for the production of green hydrogen without any stress on drinkable freshwater reservoirs, but its large-scale exploitation is harshly limited by the anodic chlorine oxidation reaction (ClOR), resulting in material corrosion and limiting the efficiency and sustainability of this technology. Consequently, active, stable, and eco-friendly electrocatalysts capable of selectively promoting the oxygen evolution reaction (OER), suppressing thus ClOR, are highly demanded for further advancements in the field. In this context, the present work reports for the first time on the fabrication ofcrystalline manganese ferrite thin films by an original chemical vapor deposition (CVD) route, starting from a mixture of Mn and Fe b-diketonate diamine adducts acting as single-source precursor for the target systems. Controlled variations of the relative precursor amounts allowed to modulate the structural and compositional characteristics of the resulting materials, with particular regard to the Mn/Fe ratio. Electrochemical tests in real seawater environments yielded, for the best performing system, an outstanding Tafel slope of z60 mV dec and enabled to rule out hypochlorite generation. These performances, accompanied by an appreciable operational stability, underscore the potential of the present electrocatalysts for renewable energy-related applications
Data-Driven Joint Complex-Valued Chance-Constrained Programs under Wasserstein Ambiguity Set
No full textIn this paper, we study data-driven chance-constrained optimization with complexvalued decision variables (3CP), motivated by complex-valued linear programs arising in signal processing and communications. To hedge against distributional uncertainty in the random coefficients, we adopt a distributionally robust formulation over a Wasserstein ambiguity set centered at the empirical distribution. For both individual and joint probabilistic constraints, we derive tractable approximations via worst-case Conditional Value-at-Risk (CVaR) reformulations. The individual constraints lead to a convex, conservative, and computationally efficient program, whereas the joint constraints yield a biconvex approximation. To address the latter, we develop a convex sequential method that produces feasible upper bounds, and we embed it within a spatial branch-and-bound framework that leverages monotonic relaxations to compute certified lower and upper bounds. Numerical experiments confirm the effectiveness of the approach: the convex sequential method stabilizes within a few iterations, and the branch-and-bound optimality gap shrinks and converges to zero (up to a prescribed tolerance) as the search tree is refined.</div
HIV persistence in tissues on dolutegravir-based therapy is not associated with resistance mutations to dolutegravir
No full textInternational audienceBackground :Relatively few studies have investigated HIV-1 persistence in tissues, especially in healthy people-living-with-HIV-1 (PLWH) on a successful antiretroviral regimen containing second generation integrase inhibitors.Methods :In the ANRS EP64 DOLUVOIR, we explore HIV-1 persistence in five accessible anatomical sites in 20 PLWH on an efficient first-line ART regimen containing dolutegravir with virological load <50 copies/mL: PBMCs, rectum, adipose tissue, lymph node and sperm. We quantify total HIV-DNA and cell-associated HIV-1 RNA in different compartments. We sequence HIV-1 DNA for searching drug resistance mutations (DRM) (in RT and INT) and for studying HIV diversity within tissues (ENV). Intact proviral DNA is estimated in PBMCs with an adapted IPDA assay.Results :Broad ranges of total HIV-DNA and transcripts levels are detected in lymph nodes, PBMCs, adipose tissue and rectum with the highest levels being found in lymph nodes (2.77 log copies HIV-1-DNA/106 cells and 1.50 log copies of HIV-1 cell-associated-RNA/µg RNA). HIV-1 DNA is undetected in all sperm samples (n = 19) except for one (1.52 log copies HIV-1-DNA/106 cells). No difference is noted between the diversity in the four compartments. DRMs to the current regimen are found archived in compartments of six participants. Only two major DRMs to dolutegravir (G118R and R263K) are found archived in two participants. They are the results of APOBEC hypermutations.Conclusions :Despite ongoing transcriptional activity, persistence of HIV-1 in deep tissues is not associated with the selection of DRMs to dolutegravir on intact proviruses. Our results suggest that the detectable transcriptional activity stems predominantly from defective proviral DNA
International Guideline Harmonization Group Recommendations for Breast Cancer Surveillance in Childhood, Adolescent, and Young Adult Cancer Survivors After Anthracyclines
No full textInternational audiencePURPOSE With new evidence emerging about breast cancer risk following anthracycline chemotherapy, the International Late Effects of Childhood Cancer Guideline Harmonization Group updated the evidence and breast cancer surveillance recommendations for female childhood, adolescent, and young adult (CAYA) cancer survivors. METHODS The Grading of Recommendations Assessment, Development, and Evaluation methodology was used to incorporate new knowledge and refine breast cancer surveillance recommendations. The guideline panel updated the systematic literature review and revised recommendations based on new evidence, clinical judgment, and assessments of benefits and harms of surveillance, ensuring adaptability across various health care systems. RESULTS The literature update revealed new findings on the effects of anthracyclines on breast cancer risk in female CAYA cancer survivors. Moderate-quality evidence shows no significant association between doxorubicin doses <100 mg/m 2 and breast cancer risk. High-quality evidence indicates a statistically significant but weak association between breast cancer risk and 100-199 mg/m 2 doxorubicin (relative risk, <2) and a moderate breast cancer risk (relative risk, 2-4) for those treated with ≥200 mg/m 2 in the absence of radiotherapy exposing breast tissue (chest radiation). Routine breast cancer surveillance after ≥200 mg/m 2 doxorubicin in the absence of chest radiation is reasonable from age 30 years onward or ≥8 years from exposure (whichever occurs last). Due to inconclusive evidence, no recommendation could be formulated for routine breast cancer surveillance after daunorubicin, epirubicin, or idarubicin, in the absence of chest radiation. CONCLUSION The newly identified evidence on breast cancer risk after anthracyclines supports changes in the 2019 recommendations regarding breast cancer surveillance for survivors treated with ≥200 mg/m 2 doxorubicin without chest radiation
Electrocaloric cooling efficiency: Comparative insights on P(VDF-TrFE-CFE) polymer and BSTM ceramics
No full textInternational audienceIn response to the increasing demand for efficient and compact refrigeration and energy conversion devices, research has focused on identifying optimal electrocaloric (EC) materials among ferroelectric ceramics and polymers. This study investigates the EC properties of the Poly [(Vinylidene Fluoride) 0.664 -(Trifluoroethylene) 0.245 -(Chlorofluoroethylene) 0.091 ] terpolymer and multi-layer Ba 0.6 Sr 0.4 Ti 0.998 Mn 0.002 O 3 (BSTM) ceramics, comparing various parameters to assess their suitability for advanced energy applications.The multilayer ceramic capacitor contains a large amount of inactive material, which hinders the performance of the capacitor both in terms of ΔT ad and efficiency. Finite-element modeling with direct temperature measurement was therefore employed to extract intrinsic electrocaloric response from geometric and diffusion effects, providing the ΔT ad and diffusion-related energy losses required for evaluating the cooling efficiency. Adiabatic temperature change (ΔT ad ) obtained in an electric field representing long-term operation, reaches 4.91 • C for Terpo at 100 V/ μm and 3.0 • C for BSTM at 30 • C. The loss in ferroelectric hysteresis is observed to be much lower in BSTM than in PVDF Terpolymer. Hence, the cooling efficiency relative to Carnot reveals that the PVDF Terpolymer achieves a relative cooling efficiency upper bound of 4.5% at 100 V/μm, whereas BSTM ceramics reach nearly 14 times, being 62.1% at 30 V/μm. The PVDF Terpolymer outperforms BSTM ceramics in terms of adiabatic temperature change and flexibility, but not in terms of expected cooling efficiency. Considering these complementary strengths, both BSTM ceramics and PVDF terpolymers emerge as promising electrocaloric materials for advanced energy applications, including solid-state cooling and energy harvesting
Evolving global oceanic nitrogen deposition under future emission pathways and responses to nitrogen emission reductions
No full textInternational audienceAtmospheric nitrogen deposition is an important external nutrient source to the global ocean, with significant impacts on marine ecosystems and biogeochemical cycles. However, its future evolution under changing anthropogenic emissions and the consequences for ocean productivity and climate-relevant gases such as N2O remain unclear. Here, the global atmospheric chemistry model GEOS-Chem is used to evaluate changes in global oceanic nitrogen deposition between 2015 and 2050 under three representative future emission scenarios and to assess their responses to multiple levels of NH3 and NOx emission reductions. Global oceanic nitrogen deposition is projected to change by −24% to +6% between 2015 and 2050, with a substantially increasing share contributed by reduced nitrogen across all scenarios. There is strong chemical compensation between reduced and oxidized nitrogen deposition: reducing emissions of one species (e.g., NH3 or NOₓ) can enhance dry deposition of the other to the oceans, particularly in coastal regions, suggesting that joint control of NH3 and NOₓ is required to reduce total nitrogen deposition effectively. The potential ocean productivity induced by nitrogen deposition may decrease from 290 Tg C in 2015 to 222 Tg C under SSP1-RCP2.6, or increase to 306 Tg C under SSP3-RCP7.0 by 2050, while concurrent changes in oceanic N2O emissions largely offset the associated climatic effects. These results highlight overlooked impacts of future climate mitigation and nitrogen abatement on marine ecosystems via altered atmospheric nitrogen deposition, and call for more holistic assessments of nitrogen impacts across the air, terrestrial, and ocean systems
L'exception féminine chinoise dans l'art vidéo (1995-2016)
No full textThis dissertation examines the emergence and singularity of women artists in Chinese video art between 1995 and 2016. It stems from a dual observation: on the one hand, women's creative work has long remained invisible within the history of Chinese art; on the other, video — as a recent and still marginal medium — has provided an unprecedented space of expression, free from traditional academic hierarchies. The Chinese feminine exception in video art thus lies at the intersection of a historical absence and a new medial opening.Drawing upon extensive fieldwork in several Chinese cities, curatorial projects, and a personal practice of video and performance, this research combines direct observation, artwork analysis, and theoretical reflection. The approach places the body and memory at the core of inquiry, viewing video not merely as a technical medium but as a living dispositif where the intimate and the collective, the visible and the invisible, intertwine.A generation of women artists has transformed video into a laboratory for corporeal, memorial, and political experimentation. Their works explore sensory synesthesia, the memory of everyday life, and the presence of the body within the urban and ruinous landscape, thereby redefining female visibility in contemporary Chinese art. In this sense, video art emerges both as the symptom of an inherited void and as an agent of historical transformation — a critical space where women reinvent the forms of freedom, gaze, and transmission.Cette recherche étudie l'émergence et la singularité des artistes femmes dans l'art vidéo chinois entre 1995 et 2016. Elle part d'un double constat : d'une part, l'histoire de l'art chinois a longtemps invisibilisé la création féminine ; d'autre part, la vidéo, médium récent et encore marginal, a offert un espace d'expression inédit, libéré des hiérarchies académiques traditionnelles. L'exception féminine chinoise dans l'art vidéo se comprend ainsi à la croisée d'une absence historique et d'une brèche médiatique.À partir d'une enquête de terrain menée dans plusieurs villes de Chine, de projets curatoriaux et d'une pratique personnelle de création vidéo- performative, cette thèse articule observation directe, analyse d'œuvres et réflexion théorique. L'approche privilégie le corps et la mémoire comme lieux d'inscription du sensible et du social. L'art vidéo y apparaît non seulement comme un médium technique, mais comme un dispositif vivant où se rejouent les rapports entre intime et collectif, visible et invisible.Une génération d'artistes femmes transforme ce médium en laboratoire d'expériences corporelles, mémorielles et politiques. Leurs œuvres explorent la synesthésie des sens, la mémoire du quotidien et la présence du corps dans la ville et la ruine, redéfinissant la visibilité féminine dans l'art contemporain chinois. En ce sens, l'art vidéo devient à la fois le symptôme d'un vide hérité et l'agent d'une transformation historique : un espace critique où les femmes réinventent les formes de liberté, de regard et de transmission
Representing dynamic grassland density in the land surface model ORCHIDEE r9010
No full textInternational audienceIn semi-arid regions, grasses and shrubs often form spatially heterogeneous patterns interspersed with bare soil as a strategy to optimize resource use and maximise productivity. Accurately representing the matrix of vegetation and bare soil in global land surface models is essential for advancing the understanding of the carbon, water, and dust cycles. This study focuses on grasslands using the land surface model ORCHIDEE (ORganizing Carbon and Hydrology In Dynamic EcosystEms), which originally assumes a globally fixed grassland density representing a fixed number of individuals per unit of land. This assumption, referred to as the fixed density approach, limits the model's ability to capture grassland responses to environmental changes, resulting in unsustainable productivity and unrealistically frequent mortality events, particularly in resource-limited regions. To address these limitations, we introduced a dynamic density approach that simulates grassland density based on indicators of vegetation growth, such as reserve and labile carbon content in the grass. The simulated grassland density was consistent with field-based estimates from five regional case studies and showed a better representation of bare soil in grasslands than the fixed density approach. The emerging positive correlation between precipitation and simulated grassland density supported the validity of the approach. Compared to the fixed density approach, the dynamic density approach substantially reduced simulated mortality events, raised the aridity threshold for frequent mortality, improved the simulated leaf area index (LAI) both globally and in key semi-arid regions, and maintained realistic grassland productivity in regions where the presence of grassland is confirmed by remotely sensed LAI. This study not only demonstrates that simulating grassland density as a function of carbon availability improves ORCHIDEE's capacity to capture grassland dynamics under environmental variability, but also provides a promising foundation for investigating dust dynamics and subsequent land–atmosphere feedbacks in (semi-)arid regions
Engineering MgFe<sub>2</sub>O<sub>4</sub> nanoparticles to enhance magnetic, optical, and dielectric performance
No full textInternational audienceThis research investigated the effects of solution pH during synthesis and annealing on the structural, magnetic, optical, and dielectric properties of MgFe2O4 synthesised using the citric acid-assisted sol-gel auto-combustion method. Structural data showed that crystallinity, lattice parameters, and cation distribution were strongly influenced by both pH and annealing temperature. Optimal morphology and crystallinity were achieved at pH 7 and an annealing temperature of 550 °C for 3 h, under which cation ordering and defect reduction were effectively achieved. Magnetic characterisation revealed a significant improvement in saturation magnetisation (20.6 emu/g) under optimal conditions, attributed to increased super-exchange interactions. The optical bandgap was modulated by more than 11% (2.04 to 2.30 eV) by adjusting pH-mediated surface chemistry and subsequent defect states. The sample synthesised at pH 9 exhibited the highest values of ε’, ε”, and σac. These results conclusively demonstrate that accurate control of synthesis pH and annealing enables the design of multifunctional properties in MgFe2O4 nanoparticles, providing a solid foundation for their application in high-end magnetic, optical, and electronic devices
Caractérisation de la porosité agglomérée dans des composites stratifié par interférométrie ultrasonore
No full textInternational audienceLocalized porosity in stratified carbon fiber-reinforced polymer (CFRP) composites can severely affect mechanical performance and structural integrity. Conventional ultrasonic attenuation methods can quantify residual porosity but cannot characterize clusters of voids. This work presents an ultrasonic interferometric approach for the quantitative assessment of localized porosity in laminated composites. CFRP specimens are manufactured in an autoclave under controlled conditions to introduce defined porosity levels. Through-transmission ultrasonic measurements are compared with an analytical multilayer propagation model including a degraded layer described by multiple scattering theory. Solving the inverse problem enabled estimation of both the location and concentration of void clusters. Results show good agreement with X-ray tomographies, confirming the capability of ultrasonic interferometry for accurate detection of localized porosity and its potential for non-destructive evaluation of laminated composites