Comparative study of three cellular materials under blast and sustained shock wave

International audienceThis study investigates the mechanical response of three cellular materials—polyisocyanurate (PIR), autoclaved aerated concrete (AAC), and Aluminum Lightweight Foam (ALF, Nufoam® 140)—under blast and shock loading conditions. The research aims to provide experimental data for optimizing building protection against explosion hazards. Laboratory-scale tests were conducted using a shock tube to generate blast and sustained shock waves. The materials’ responses were analyzed using high-speed imaging and digital image correlation. Results indicate that PIR exhibits significant deformation under sustained shocks but shows recovery under blast loading. AAC demonstrates erosion-based energy dissipation, with material loss concentrated at the extremities. ALF, serving as a reference, shows excellent mechanical energy dissipation. The study highlights the potential of these materials for applications requiring both thermal insulation and blast resistance, contributing to the development of predictive tools and larger-scale experiment designs

Parameters Impacting Brake Wear Particle Emissions: A Literature Review

International audienceWith the implementation by the European Union since the 1980s of strict measures to reduce emissions of air pollutants (PM10, PM2.5, NH3, CH4, O3, NOX, SOX, VOCs (volatile organic compounds), etc.), these emissions have fallen from a total of nearly 65 million tons in 1990 to around 20 million tons in 2021, according to data from the European Environment Agency. In the road transport sector, the implementation of the first European emissions standard in 1992 and the electrification of vehicles have made it possible to reduce exhaust emissions. As non-exhaust emissions increased, the European Commission introduced thresholds for braking systems for certain vehicle categories in the future Euro 7 standard. Car manufacturers are looking for solutions to reduce brake particle emissions, including the modification of the composition of the brake pads and discs. This literature review aims to present the state of the art of a set of parameters that can influence brake particle emissions. The parameters highlighted here include the raw materials and manufacturing process parameters of the brake pads, the composition of brake discs, some test parameters, and some characteristics of brake pads and discs. A brief analysis of the tribological mechanisms that could be involved in particle emissions is also described

2D analytical solution of a multilayered hollow cylinder subjected to non-uniform loads

International audienceIn this paper, a new analytical solution has been developed using the recursive method to assess stresses,strains and displacements in the cross-section of an elastic multilayered hollow cylinder subjected to nonuniforminternal and external loads. Using Michell's analysis of the stress function and Hooke's law, wederived the analytical solution and compared it to the numerical results obtained using FDM software. Theanalytical and numerical results are in perfect agreement and lead to the conclusion that the nonuniformityof the loading significantly influences the amplitudes of the orthoradial stresses. Theseorthoradial stresses may not always be equal to the maximum principal stress, depending on the positionwithin the layer. This result suggests that it is not possible to find an analytical solution in the elastoplasticframework where the fracture criterion is expressed in terms of principal stresses, σ1 = σrr or σθθ, depending on the position considered. The present study makes it possible to deduce the non-uniform loading at theinterface of 2 layers by minimizing the deviations with stress and / or strain measurements in one of thelayers of the hollow cylinder. This study should also help to understand the influence of a low stiffnessmaterial interspersed between rigid materials

Maternal exposure to pesticides and gestational diabetes mellitus in the Elfe Cohort

International audienceBackground: Gestational diabetes mellitus (GDM) increases risks of adverse perinatal outcomes and metabolic disorders in offspring. Some endocrine-disrupting chemicals are presumed to interfere with glucose metabolism. We aimed to assess the association between non-occupational exposures to pesticides and the risk of GDM.Methods: The study was conducted on 11 512 women (791 with GDM) from the French nationwide Elfe cohort. Among 114 suspected pesticides identified using a toxicogenomic approach, 62 with detection frequency ≥10 % were analyzed across three sources of exposure: residential use (self-reported, n = 18), agricultural (geographic information system, n = 14) and dietary (estimated by a food-frequency questionnaire and monitoring data of pesticide residues in foods, n = 30). The association between exposure to pesticides (no or low vs. high) and the occurrence of GDM was tested with single and multi-source adjusted logistic regression models.Results: In the multi-source model, dietary exposure to glyphosate (aOR = 0.6, 95 %CI: 0.5,0.9) or agricultural exposure (aOR = 0.8, 95 %CI:0.6,1.0) were associated with lower odds of GDM. The same effect was identified for two dietary pesticides: epoxiconazole (aOR = 0.6, 95 %CI: 0.5,0.8) and penconazole (aOR = 0.8, 95 %CI: 0.6,1.0). Dietary exposure to cypermethrin (aOR = 1.2, 95 %CI:1.0,1.5) and agricultural exposure to myclobutanil (aOR = 1.4, 95 %CI:1.1,1.9) were associated with higher odds of GDM. No significant association was identified for the residential use of pesticides.Conclusion: This toxico-genomic-based study identifies five pesticides associated with GDM through agricultural or dietary exposure. These findings provide new insights into environmental contributors to GDM. Further research is needed to elucidate the underlying toxicological mechanisms and confirm these associations

Relargage des PFAS dans les sols et les eaux souterraines

International audienceCes travaux portent sur l’étude du relargage et du transfert des substances per et polyfluoroalkylées (PFAS) dans les sols et les eaux souterraines. Ces substances, présentes dans de nombreux produits industriels de consommation courante, sont persistantes et ubiquitaires dans l’environnement, et sont toxiques pour l’Homme. En 2023, un plan d'action ministériel sur les PFAS a été mis en place pour améliorer la compréhension des émissions de ces polluants et de leur présence dans l'environnement, en particulier dans les milieux aquatiques, afin de réduire l'exposition des populations. En 2024, ce plan a été intégré dans un plan d'action interministériel, pour structurer les actions en réponse aux préoccupations grandissantes concernant les impacts des PFAS sur la santé humaine et la biodiversité. Ces travaux visent à acquérir des connaissances scientifiques sur le comportement des PFAS dans les sols, en se concentrant sur la détermination des mécanismes et des paramètres principaux régissant le relargage et le transfert des PFAS dans les zones saturées et non saturées du sol

evaltools

The Python package `evaltools` is designed to assess surface atmosphere composition prediction models against in-situ observations. This package provides several tools to compute model scores and plot them. It is used for evaluation of air quality models from the Copernicus Atmosphere Monitoring Service (CAMS).The concept of `evaltools` is to compare observations (measured over time at fixed lat/lon locations) with simulations (wich may have a forecast horizon of several days) computed over a period of several days. Therefore, it can be suitable for other data types such as AERONET data, but will not handle data with a vertical component.Up-to-date source code and documentation are available at https://github.com/UMR-CNRM/EvalTool

An Ensemble Machine Learning Approach for Predicting Sources of Organic Aerosols Measured by Aerosol Mass Spectrometry

International audienceLong-term source apportionment of atmospheric organic aerosols (OA) is essential for supporting air pollution management strategies. While aerosol mass spectrometry (AMS) combined with traditional source apportionment tools can accurately identify various OA sources, they face efficiency challenges when processing large volumes of long-term data. This study proposes an ensemble machine learning approach to efficiently apportion OA sources from long-term AMS measurements. Using six-year observation of a simplified version of AMS (i.e., ACSM) in the Paris region along with OA factor data derived from positive matrix factorization analysis, we developed an ensemble machine learning source apportionment model. Compared to individual machine learning algorithms, the ensemble model substantially reduced the root-mean-square error (RMSE) and increased the correlation coefficient in predicting OA sources by approximately 30% and 5%, respectively. Sensitivity analysis with five years of baseline data revealed that model performance relatively stabilizes when the training data exceeds two years, with RMSE values for primary and secondary OA factors at 0.31–0.45 μg/m3 and 0.69–0.84 μg/m3, respectively. This ensemble model not only enhances the efficiency of long-term OA source apportionment but also holds potential for near-real-time online applications

Development of a single biofilm extraction method for non-target analysis and bioassays to monitor wastewater micropollutants

International audiencePassive samplers (PS) are strong tools to monitor micropollutants due to their ability to accumulate andconcentrate the pollutants present in water. Among existing PS, those using biofilms as a receiving phasehave gained interest for environmental monitoring, notably in waste water, for which conventional PS arelimited by biofouling. Extraction and (bio)analysis of contaminants adsorbed in biofilms still needoptimisation in monitoring context. Non-target analysis has been increasingly used during the last decadeto detect a large range of water micropollutants, including emerging contaminants, which positions it as agreat tool for environmental monitoring. However, this method does not account for the biologicalactivities of the compounds, and the impact of mixture effects on their activity. Hence, as acomplementary approach, in vitro bioassays provide a global bioactivity profile of the water sampleswhile considering all the bio-active micropollutants and their potential mixture effect. The combination ofPS with bioassays and chemical analysis has already shown its effectiveness in characterizing water.This work aims to develop an approach based on the coupling of an innovative biofilm -based PS withnon-target screening and in vitro bioassays to characterize wastewater. This presentation will mainly focuson the development a single biofilm extraction method for both non -target analysis and bioassays,allowing us to have a robust correlation between the compounds analysed and the activity measured.Several solvents, extraction methods, and clean-up strategies were implemented and compared for biofilmextraction. The extracts were then subjected to chemical analysis and in vitro bioassays. For the chemicalanalysis performed on a liquid chromatography coupled to a high-resolution mass spectrometry, theextraction efficiency was evaluated based on characteristics such as standard recoveries, number ofcommon and specific compounds detected with suspect screening, number of common and specificunknown features detected, and range of molecular weight or polarity. For bioassays, the evaluations wereassessed on the response of four nuclear receptors (estrogenic, androgenic, pregnane X, and arylhydrocarbon receptors).Based on the outcome of the results obtained for these tests, a single extraction protocol offering the bestefficiency compromise for both chemical analysis and in vitro bioassays will be presente

A Review of the Evidence of the Toxicity of Chemical Substances Included in the European Union Ambient Air Quality and Drinking Water Directives: Perspectives for Health Impact Assessments

International audienceThe European Union (EU) Ambient Air QualityDirective (AAQD) and Drinking Water Directive (DWD) are aimedat maintaining and improving air quality and ensuring high standardsfor potable water across the EU. Besides several other indicators, theAAQD and DWD consist of chemical parameters (substances orsubstance groups) that are regulated within this framework. All thesubstances are associated with various health outcomes, and many ofthem are classified as carcinogenic or probably/possibly carcinogenicwith causal links. To quantify the health burden of the chemicalsubstances included in the AAQD and DWD, we need informationregarding population exposure, current baseline mortality/morbidityrates in the populations, and exposure−response functions (ERFs) orunit risks (URs) from previous epidemiological studies. During thisstudy, we analyzed the availability of ERFs or URs and discussed their applicability in health impact assessments (HIAs). From theHIA perspective, ERFsin terms of relative risk (RR), standardized mortality ratio (SMR), odds ratio (OR), or UR datawereavailable for many of the analyzed substances. However, for some substances such as acrylamide, antimony, boron, chlorate andchlorite, copper, microcystin-LR, and selenium, no risk measures could be identified. The aim of this study is to derive ERFs, whichwill allow HIAs for a larger number of chemicals when exposure data and baseline mortality/morbidity data are available. Currently,HIAs have largely focused only on main ambient pollutants such as particulate matter (PM10), fine particulate matter (PM2.5),nitrogen oxides (NOX), and ozone (O3). In contrast, health risks related to exposure to chemicals are much more diverse, and thehealth burdens should be quantified to a much greater extent

Bioaccessibilité des métaux/métalloïdes dans les sols : un indicateur pertinent en santé-environnement

International audienceLa bioaccessibilité orale simulant la digestion humaine est un outil de plus en plus utilisé et reconnu pour affiner l’exposition de l’Homme aux éléments métalliques en lien avec l’ingestion de particules de sol [1]. Le test in vitro normé UBM (ISO 17924:2019 [2]) est recommandé dans la méthodologie nationale de gestion des sites et sols pollués, actuellement validé in vivo/in vitro pour As, Cd et Pb. Pour As, la Haute Autorité de Santé (HAS ; [3]) recommande de dépister les populations dès lors que la concentration en As bioaccessible est supérieure à 25 mg/kg. Deux études illustrent la pertinence de la bioaccessibilité comme indicateur santé-environnement. La première visait à réaliser une étude statistique de la distribution en As bioaccessible à l’échelle nationale en considérant les sols du RMQS. Ainsi, sur les 353 échantillons considérés, à une exception près, les concentrations bioaccessibles sont inférieures à la valeur seuil de 25 mg/kg, avec une bioaccessibilité moyenne inférieure à 10 %. La seconde étude visait à élargir la portée du test UBM à d’autres éléments métalliques, notamment Cr et Ni. Leur bioaccessibilité montre des valeurs moyennes relativement faibles (< 10 % pour Cr et < 20 % pour Ni), indiquant qu’une part importante de la concentration totale de ces éléments est retenue dans le sol et peu disponible lors de la digestion. Ces résultats, très prometteurs, montrent l’intérêt de prendre en compte ce paramètre dans l’évaluation des risques sanitaires, mais sa validation est nécessaire au préalable par l’essai de biodisponibilité, réalisé sur un modèle porcelet