Opportunities from energy-loss near-edge fine structure analysis to track chemical and structural damage in zircon

International audienceZircon (ZrSiO4) is the oldest-known mineral of Earth and an ubiquitous silicate in geochronology. More specifically, the accumulation of alpha decay damage in zircon over time significantly affects its physical and chemical properties, and can lead to a disturbance of the ages measured in this mineral. Therefore, analytical tools that enable comprehensive structural and chemical information at the nanoscale in this compound are highly sought after. In this context, we explore the electron energy-loss fine structures resulting from the excitation of O1s and Si2p core electrons in zircon, which are interpreted from ab initio calculations in a single-particle framework. An excellent agreement is obtained between the experimental and calculated fine structures, emphasizing the large distortion of the final electronic states induced by the core-hole potential. The O-K edge is particularly rich in information, with intense peaks dominated by O2p - Zr4d and O2p - Si3sp hybrids. This work suggests that the near-edge structures from the O1s and Si2p excitations accessible from electron energy-loss spectroscopy or X-ray absorption spectroscopy could be used as tools to follow, interpret and understand structural and chemical modifications in zircon subject to natural radiation damage. We illustrate the potential of this approach through the evolution of near-edge fine structures in a zircon sample that exhibits a locally amorphized zone formed by ultrafast laser excitation

Prevalence of mealybug wilt-associated viruses in pineapple 'Queen Victoria' cultivars in Reunion Island and the potential of virus-free vitroplants for disease management

Source Agritrop Cirad (https://agritrop.cirad.fr/615299/) * Autres projets (id;sigle;titre): ;;(REU) Dispositif de partenariat en santé et biodiversité//International audienceMealybug wilt disease of pineapple (MWP) poses a significant threat to global pineapple production, yet its etiology remains poorly understood. The disease is believed to involve mealybugs, multiple pineapple mealybug wilt-associated viruses (PMWaVs, genus Ampelovirus), and possibly other viruses from the Badnavirus, Secovirus, and Vitivirus genera. This study examines the distribution and prevalence of three ampeloviruses (PMWaV1, PMWaV2, PMWaV3) and two badnaviruses (PBERV, PBCOV), previously associated to MWP symptoms, across 15 pineapple plots of the 'Queen Victoria' cultivar in Reunion Island. A total of 450 symptomatic and asymptomatic leaf samples were analyzed using PCR and RT-PCR-based diagnostics. Globally, 93 % of samples were infected with at least one virus, and 76 % were co-infected with two to four viruses. PMWaV1 (78 %) and PBCOV (87 %) were the most prevalent, while PBERV was not detected. Virus presence was associated with leaf dieback, wilting, and curling. Leaf reddening and yellowing, commonly associated with MWP, were not associated with viral infection, suggesting that other biotic or abiotic factors may be responsible for these symptoms. Viral infections and MWP symptoms were significantly lower in plots planted with vitroplants (VPs) compared to those using suckers, highlighting the potential of VPs in reducing viral infections. These findings highlight the complexity of MWP and underscore the potential benefits of using virus-free VPs to manage the disease

Diffusive gradient in thin film for ultra-trace methylmercury measurements in the coastal and open sea

International audienceMonomethylmercury (MMHg) is a potent neurotoxin causing neurodevelopmental delays and cardiovascular and immunological issues. Human exposure primarily occurs through seafood consumption due to MMHg bioaccumulation and biomagnification from seawater into marine organisms. Determining MMHg in seawater at ultratrace concentrations poses logistical and analytical challenges. Diffusive Gradient in Thin-film (DGT) samplers represent a promising solution, which captures time-averaged concentrations by preconcentrating in situ MMHg over a defined exposure time. DGT manufactured with 3-mercaptopropyl-functionalized silica (3MFS) in agarose and polyacrylamide gels were tested and compared for the determination of MMHg present in open ocean and coastal waters. Different elution methods using acidic thiourea were tested to reach precise, accurate and quantitative elution of MMHg from the binding gel. We found that polyacrylamide-3MFS binding gels display a higher elution efficiency (94 ± 3 %), precision and better handling compared to agarose-3MFS gels (41 ± 6 %). A unique mooring line installed in the South Western Tropical Pacific Ocean, provided monthly DGT-MMHg concentrations over a year showing potential seasonal differences in MMHg concentrations ranging between 18 and 106 fM. DGT were also deployed in shallow Peruvian coastal waters, exhibiting higher MMHg concentrations (170 ± 97, n = 26) with typical benthopelagic gradients. DGT-MMHg concentrations were in good agreement with discrete water samples analyzed by reference methods using isotope dilution. DGTs offer complementary advantages over oceanographic cruises, notably in situ preconcentration, low blanks, minimal logistical requirements and cost-effectiveness. DGTs represent a valuable tool for studying the marine MMHg cycle for evaluating the implementation of the Minamata Convention.</div

Exner diagnosis method for two-fluid morphodynamics simulations

International audienceMass balance in sediment transport is often associated with single-phase flow model through the resolution of the Exner equation. In this contribution, the mass balance is derived from the two-phase flow, two-fluid, model equations and compared with the conventional single-phase flow approach. Five terms are identified from the two-phase flow formulation: the bed evolution, the storage evolution, the lateral flux, the bed flux and the top flux. Three different flow configurations with increasing complexity are tested, namely a one dimensional pure sedimentation, a two dimensional scour downstream an apron and a three dimensional scour around a vertical square cylinder. The mass balance formulation identifies the driving process of an erosion or a deposition process in each case. This approach can be applied on other configurations related with sediment flux and morphology bed evolution such as scour process

City Makers and the Politics of Urban Diversity Governance. Comparative Approaches from Europe and Asia

International audienceThis open access book examines the rising challenges of managing diversity in European and Asian cities. It spotlights the roles of varied city makers - from urban leaders to migrant communities and civil society activists - in negotiating and transforming their city’s diversity governance. The book brings together the contributions of urban studies and migration studies scholars, which offer rich empirical analyses on various European and Asian cities, such as Paris, Singapore, Barcelona, and Guangzhou. Adopting a comparative lens, the book presents a decentered understanding of 'super-diverse' cities, examining shifts in urban policy-making within different geographical contexts, with distinct patterns of migration and diversification. By advancing urban comparison as a research tool, it contributes to the contemporary discussions on the local turn of migration and diversity policies

Spillover from flower plantings benefits apple pollination on a small scale

International audienceAnimal-mediated pollination is critical to support crop yields but is threatened by the decline of pollinator populations. The establishment of flower plantings in agricultural landscapes is a conservation strategy that aims to provide diverse floral resources for pollinators. Despite several studies on the effect of flower plantings on pollination, their effects remain unclear. In particular, the influence of the distance has been studied through theoretical approaches but field studies are scarce. We conducted field experiments over two years, 2023 and 2024, in the Provence-Alpes-Côte d'Azur region of France, to investigate how co-flowering plantings affect insect flower visitation and crop pollination in apple orchards. We found that the abundance of apple flower visitors, especially wild bees, decreased with the distance from flower plantings, thus suggesting a spillover of flower visitors from flower plantings into adjacent apple trees. Interestingly, we found a non-linear effect of the distance from flower planting on the initial fruit set, which suggests that flower plantings can improve apple pollination at close distances from the plantings (about 33 m). No effect of the distance from flower plantings was observed on the diversity of flower visitors, final apple fruit set or fruit quality. Overall, our results suggest that flower plantings are a promising strategy to support pollinators. Furthermore, as they can increase pollinator abundance in the adjacent apple flowers, flower plantings have the potential to enhance pollination and yield of the adjacent crops. Given the short distance of the observed facilitation effect, we recommend that flower plantings should be spread across farmland in order to promote crop pollination at farm level

High alpine preglacial caves modified by glacial processes and late condensationcorrosion in the Scerscen Valley (Valmalenco, Western Alps, Italy)

International audienceThe Scerscen Valley (western Italian Alps) is home to caves at an altitude of around 2600 m, opening close to the Speleogenesis edge of a glacier. The aim of the research as part of a multi-disciplinary project was to reconstruct the evolution Alpine Cosmogenic GeomorphologyHydrogeologyglaciersburial dating of cosmonucleide some the of caves the related most burial recent to dating, the processes, geological recorded such and morphology paleoenvironmental as condensation-corrosion and micrometeorology, evolution and of sediment the carried area deposition. and out mineralogical to evaluate We the performed identifirole of cation by XRD, and hydrogeology using dye tracing and physical and chemical analyses. The cosmonucleide dating of quartz pebbles showed that the Veronica Cave is the oldest, with deposits dated at 1.3 ± 0.4 Ma, and possibly even older. It certainly formed at a much lower altitude (approx. 1300 m a.s.l. or lower) during the Alpine uplift. The Morgana and Marsooi caves, given the smaller volume of their phreatic conduits (1/3 of Veronica), are possibly more recent, formed during interglacials and evolved close to a glacial body. The caves initiated in dolomitic marble under the influence of sulfuric acid speleogenesis (SAS) due to pyrite oxidation. The conduits were then enlarged dramatically under phreatic conditions. The caves have evolved since their preglacial formation, with phases of filling by fluvio-glacial sediments and unclogging. Water tracing and physico-chemical analysis attest to a well-karstified aquifer, with rapid water circulation (&gt;20 m/h) and low temperatures (~2 °C), draining towards the main spring, "La Prediletta", located at the foot of the dolomitic marbles. Microclimatic records (cave temperature and humidity) show seasonal cycles of condensation and evaporation, influenced by air exchanges with the outside atmosphere. These processes contributed to the formation of secondary minerals by evaporation (gypsum, hydromagnesite…) and, above all, to the significant enlargement of passages by the retreat of walls with characteristic morphologies (facets and grooved walls). The Scerscen caves bear witness to a long geological and climatic history, from their formation before the Mid-Pleistocene ice ages to their present-day evolution. They offer valuable insights into karst processes in the high mountains, and interactions between glaciers and aquifers

Metal complexes – metal nanoparticles hybrid systems

International audienceOne of the natural outcomes of the progress of coordination chemistry and nanochemistry is the development of hybrid nanomaterials that combine metal complexes and zerovalent metal nanoparticles. The linkage between these two components can rely on different interaction modes (covalent, ionic, π or host-guest interactions). The influence on the native properties of each component has been studied, and sometimes shows synergy. The advantages of such combined systems have been assessed in various fields, among which electronics, catalysis, biomedicine, and environmental applications, in which they have shown promising results. To shed light on this emerging field of coordination chemistry, and potentially contribute to its development, this review summarises the main strategies used to synthesize nanohybrids based on metal complex -metal nanoparticle association. The goal is to highlight the challenges associated with their synthesis and characterization, with emphasis on the combination of techniques used to elucidate their structure

Growth, metabolic, and immune responses of lean and fat rainbow trout lines during a starvation-refeeding cycle

International audienceUnderstanding how fish with divergent energy reserve profiles respond to feed deprivation is critical for optimizing aquaculture feeding strategies. In this study, we compared two rainbow trout (Oncorhynchus mykiss) lines selected for low (lean, L) or high (fat, F) muscle lipid content. Both lines underwent a 3-week starvation period followed by 3 weeks of refeeding using self-feeders. The L line exhibited faster post-refeeding growth, higher post-refeeding weight gain, and earlier feeding activity concentrated in the morning. Conversely, the F line showed greater weight loss during starvation, reduced haematocrit and innate immune parameters, and limited metabolic recovery. Starvation induced distinct changes in lipid and protein metabolism, hydromineral regulation, and immune responses, with the F line being more metabolically and immunologically impacted. Plasmatic concentrations of calcium and sodium decreased, while chlorides concentrations increased transiently. Principal Component Analysis revealed stronger physiological disruption in the F line during starvation. These findings highlight how fat reserves influence recovery from nutritional stress, offering perspectives for genotype-specific feed management in aquaculture

Digging deeper: deep joint species distribution modeling reveals environmental drivers of Earthworm Communities

International audienceEarthworms are key drivers of soil function, influencing organic matter turnover, nutrient cycling, and soil structure. Understanding the environmental controls on their distribution is essential for predicting the impacts of land use and climate change on soil ecosystems. While local studies have identified abiotic drivers of earthworm communities, broad-scale spatial patterns remain underexplored. We developed a multi-species, multi-task deep learning model to jointly predict the distribution of 77 earthworm species across metropolitan France, using historical (1960–1970) and contemporary (1990–2020) records. The model integrates climate, soil, and land cover variables to estimate habitat suitability. We applied SHapley Additive exPlanations (SHAP) to identify key environmental drivers and used species clustering to reveal ecological response groups. The joint model achieved high predictive performance (TSS >0.7) and improved predictions for rare species compared to traditional species distribution models. Shared feature extraction across species allowed for more robust identification of common and contrasting environmental responses. Precipitation variability, temperature seasonality, and land cover emerged as dominant predictors of earthworm distribution but differed in ranking across species and functional groups. Species clustering into response groups to climatic, land use and soil revealed distinct ecological strategies including a gradient of sensitivity to precipitation seasonality, differential habitat preferences in terms of vegetation cover and wetness and trade-offs between soil acidity and organic matter quality. Our study advances both the methodological and ecological understanding of soil biodiversity. We demonstrate the utility of interpretable deep learning approaches for large-scale soil fauna modeling and provide new insights into earthworm habitat specialization. These findings highlight land cover and seasonal climate variability as efficient proxies for soil biodiversity, providing actionable indicators for global monitoring initiatives and helping to identify habitat requirements of earthworm species to guide emerging earthworm conservation strategies in the face of global environmental change