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Pertinence écologique des biomarqueurs d'immunotoxicité en surveillance environnementale
No full textThe natural variability of cellular innate immunomarkers in a model species in ecotoxicology, the three-spined stickleback, Gasterosteus aculeatus was studied in order to determine immunomarker reference values useful for passive biomonitoring Thus, effects of three confounding factors, sampling period, sex, and fish body size, were investigated in controlled laboratory conditions. This first phase enabled the construction of a mathematical model that predicts immunomarker mean values in function of the three considered confounding factors, along with a range of reference values in laboratory conditions. To be used for biomonitoring, it is important to know if the laboratory model is correctly predicting other conditions. Therefore, laboratory reference ranges were compared to data obtained from fish sampled in semi-natural conditions (mesocosm conditions) and fish sampled in natural conditions, in one uncontaminated site (field condition). Results of this comparison allowed to construct a predictive model of the natural variations of immunomarker values in each experimental condition. Tested in a biomonitoring context, the use of field reference range allowed to i) discriminate between contaminated and uncontaminated sites and ii) identify false positives that are due to the morphological heterogeneity of fish sampled in the different sites.Ce travail propose d’améliorer les connaissances sur la variabilité naturelle des immunomarqueurs cellulaires innées chez un poisson modèle en écotoxicologie, l’épinoche à trois-épines, Gasterosteus aculeatus. Il a pour but la détermination de valeurs de référence utilisables dans un contexte de biosurveillance passive pour chacun des immunomarqueurs considérés. Ainsi, l’effet de trois facteurs confondants, que sont la période de prélèvement, la taille et le sexe des organismes, a été étudié en conditions contrôlées de laboratoire. Il a été ainsi possible d’obtenir, pour chaque immunomarqueur, un modèle donnant sa valeur moyenne en fonction des trois facteurs confondants, ainsi qu’une plage de valeurs de référence laboratoire. Dans une optique d’utilisation en biosurveillance, il est important de savoir si ce modèle laboratoire peut être utilisé dans d’autres conditions. Dans un second temps, les plages de référence laboratoire ont été confrontées à des données issues de poissons élevés en conditions semi-naturelles (condition mésocosme) et à des données in situ d’un site témoin (condition terrain). Les résultats de cette confrontation ont permis la construction d’un modèle prédictif des variations naturelles des immunomarqueurs dans chaque condition expérimentale. Testées dans un contexte de biosurveillance, l’utilisation des plages de référence terrain a bien montré la capacité de discriminer les sites témoins et contaminés. De plus, cette méthode a favorisé la la détection de faux positifs, induits par une hétérogénéité morphologique des poissons prélevés sur les différents sites, issus des résultats obtenus avec des procédures statistiques classiques
Modélisation d'un jet chargé en nanoparticules à partir d'une fuite de canalisation de transport
No full textSince a few years, nanomaterials are more and more used in industrial process. In order to protect the population and the environment from the consequences of an accidental release into the atmosphere, the risk assessment allowed to identify the accidental scenario in transport, manipulation and storage of those products. The accidental leakage of the conveying pipe may lead to a massive release of nanoparticles. In order to evaluate the consequences of this type of accident, our study focuses on the prediction of particles properties dispersed into the air, for example the particle number concentration and the particle diameter distribution. The first step of the study consists in the analyse of physical phenomena related to nanoparticles in order to choose the most predominant physical phenomena to model. The relevant physical phenomena in the present configuration are the agglomerate complex shape, the drag force on agglomerates, the agglomerate breakage by gas, the agglomerate collision and the agglomeration. After that, the modelling of physical phenomena chosen is developed in CFD tool Code\_Saturne. For each physical phenomenon, a simulation test case is realized in order to verify the development in CFD tool. A good agreement between CFD tool Code\_Saturne and 0D tool from Scilab and model in the literature is obtained. Also in the present study, new model for the collision probability of agglomerates is proposed. This new model is validated with the numerical experiment. After that, the numerical tool developed is applied in a simulation of an accidental pipe leakage. The field near the leakage is simulated by Code\_Saturne. The results from Code\_Saturne is used as the input data for ADMS tool, a simulation tool for the particle dispersion in large scale. The results show that the particles are dispersed more than 1 km from the release source, which is in agreement with the distance observed. In perspective, the influences of different parameters as the wind field and the particle properties, on the agglomerate size and number distribution can be tested. An experiment of the microparticle jet is realized at INERIS in order to be able to assess the nanoparticle jet experiment in the laboratory scale.Depuis quelques années, les nanomatériaux sont de plus en plus utilisés dans les processus industriels. Afin de protéger la population et l'environnement des possibles conséquences lors de rejets accidentels de ces produits dans l'atmosphère, des analyses de risques ont permis d'identifier des scénarios accidentels dans le cas du transport, de la manipulation et du stockage. Parmi les cas de fuite non intentionnelle dans l'atmosphère libre, la fuite accidentelle sur un convoyeur peut générer un relargage massif de nanoparticules. Afin d’évaluer les conséquences de ce type de scénario accidentel, notre étude s’intéresse à la prédiction des propriétés du nuage de particules dispersées dans l’air, par exemple la concentration en nombre et la distribution des diamètres. La première étape de l’étude consiste à synthétiser les phénomènes physiques des nanoparticules dans l’air afin de choisir les phénomènes physiques les plus pertinants à modéliser. Les phénomènes physiques à modéliser sont la forme complexe des agglomérats, la force de traînée des agglomérats, la fragmentation des agglomérats par le fluide, la collision et l'agglomération des agglomérats. Ensuite, la modélisation des phénomènes physiques est développée dans l'outil CFD Code\_Saturne. Pour chaque phénomène physique, un cas de simulation numérique est réalisé pour vérifier le développement de la modélisation dans l'outil CFD. Une bonne comparaison des résultats CFD avec les résultats de modèle 0D de Scilab et les modèles dans la littérature est obtenue. Egalement dans notre étude, un nouveau modèle de la probabilité de collision des agglomérats est proposé. Ces nouveaux modèles sont validés par les expérimentations numériques. Ensuite, l'outil CFD développé est appliqué dans une simulation d'une fuite de canalisation de transport. La zone proche de la fuite est simulée par Code\_Saturne. Les résultats du Code\_Saturne sont utilisés comme les données entrées pour ADMS, un outil numérique de la dispersion des particules à grande échelle. Les résultats montrent que les particules sont dispersées plus de 1 km par rapport au terme source, ce qui est en accord avec la distance observée. En perspective, l'influence de plusieurs paramètres comme la vitesse du vent, les propriétés des particules comme la distribution de taille ou la concentration en agglomérats pourrait être testé. Une expérimentation de rejet des microparticules est réalisée à l'INERIS pour ensuite pouvoir étudier les rejets des nanoparticules à l'échelle laboratoire
Développement d’une boîte à outils CFD (MERLIN) pour tester les stratégies de modélisation en ingénierie : application à la simulation d’explosions (industrielles) à grande échelle
No full textThe use of CFD (Computational Fluid Dynamics) software for the numerical prediction of difficult experiments such as the consequences of gas explosions in industrial environments remains a major challenge in process engineering. From the state of the art in this area of research where numerical simulation results have been compared to valid experimental results, it is concluded that these software can not contribute to improve safety (the differences between experimental results and numerical results are important). However, given the potentiality of the field of Computational Fluid Dynamics, it would probably be unreasonable to marginalize it in hazard studies. This thesis helped to define strategies for estimating the consequences of explosions by CFD. Part of the work carried out consisted in determining the most common equations, techniques, models and methods in the most used CFD software (in the framework of study concerning the prediction of the consequences of an explosion in industrial environments). The URANS technique (Unsteady Reynolds Averaged Navier-Stokes) was chosen for the numerical resolution of the fundamental laws of fluid mechanics. The kepsilon turbulence model and one of its variants (the low Reynolds number kepsilon model) were selected for the turbulence simulation. The modeling of reactive flows is established using the CREBCOM model (CRiteria and Experimentally Based COmbustion Model) and the EDM model (Eddy Dissipation Model). The finite volume method has been used for the discretization of continuous equations (the laws of fluids mechanics and associated turbulence and combustion models). The convective terms of these equations are solved using the numerical scheme of Roe and that of Van-Leer. The discretization of the diffusive terms was carried out using classical centered schemes. The unsteady terms are solved using the explicit Euler method. The selected meshes are of type Voronoi and of type structured and re-cutting using the AMA technique (Anisotropic Mesh Adaptation). Boundary conditions used are mainly Dirichlet type and Neumann type. To go beyond the user aspects and have a perfect control of the software used (only pledges of a good analysis of the physical and mathematical content of CFD tools), a CFD software called MERLIN has been fully developed. It contains all the equations, techniques, models and methods selected previously and was used for all numerical simulations performed in this thesis. In order to ensure the reliability of the experiments performed with MERLIN, its verification was carried out using the MMS (The Method of Manufactured Solutions) method. To understand the numerical representation of the physical phenomena associated with the phenomenon of the explosion, we first carried out a study on shock wave propagation in different configurations (subsonic case of the Sod’shock tube problem, reflection of an unsteady shock on a compression ramp, supersonic flow on a rising step). As a result, the accuracy of a shock wave structure predicted numerically depends on the numerical scheme and the type of mesh used. The choice of the numerical scheme and type of mesh depends on the type of shock wave to be simulated numerically. The second study performed consisted in simulating the dispersion of gas. This numerical experiment revealed that a good numerical approximation of gas dispersion is independent of the numerical scheme chosen but rather relies on the turbulence model and the type of mesh used. The choice of the turbulence model is relative to the presence or not of confinement and the type of mesh depends on the flow. The last study carried out concerns the simulation of flame propagation in different configurations (confined and unconfined environments, with and without obstacles). It demonstrates that the accuracy of a numerical prediction of the flame behavior flame is based on the choice of the combustion model and the type of mesh.L’utilisation des logiciels CFD (Computational Fluid Dynamics) pour la prédiction numérique d’expériences difficiles telles que les conséquences des explosions de gaz en milieux industriels reste un enjeu majeur en génie des procédés. A partir de l’état de l’art dans ce domaine de recherche où des résultats de simulations numériques ont été comparés à des résultats expérimentaux valides, on conclut que ces logiciels ne peuvent pas contribuer à améliorer la sécurité (les écarts entre résultats expérimentaux et résultats numériques ont été comparés à des résultats expérimentaux valides, on conclut que ces logiciels ne peuvent pas contribuer à améliorer la sécurité (les écarts entre résultats expérimentaux et résultats numériques sont importants). Cependant, au vu des potentialités que regorge le domaine de la mécanique des fluides numériques (CFD), il serait sans doute déraisonnable de la marginaliser dans les études de danger. Cette thèse a contribué à définir des stratégies d’estimation des conséquences des explosions par la CFD. Une partie des travaux réalisés a consisté à déterminé les équations, techniques, modèles et méthodes les plus fréquents dans les logiciels CFD les plus utilisés (dans le cadre d’études de prédiction des conséquences d’une explosion en milieux industriels). La technique URANS (Unsteady Reynolds Averaged Navier-Stokes) a été retenue pour la résolution numérique des lois fondamentales de la mécanique des fluides. Le modèle de turbulence k-epsilon ainsi qu’une de ses variantes (le modèle k-epsilon à bas nombre de Reynolds) ont été sélectionnés pour la simulation de la turbulence. La modélisation des écoulements réactifs est effectuée en utilisant le modèle CREBCOM (CRiteria and Experimentally Based COmbustion Model) et le modèle EDM (Eddy Dissipation Model). La méthode des volumes finis a été utilisée pour al discrétisation des équations continues (les lois de la mécanique des fluides ainsi que les modèles de turbulences et de combustion qui y sont associés). Les termes convectifs de ces équations sont résolus à l’aide du schéma numérique de Roe et celui de Van-Leer. La discrétion des termes diffusifs a été effectuée en utilisant des schémas centrés classiques. Les termes instationnaires sont résolus à l’aide de la méthode d’Euler explicite. Les maillages sélectionnés sont de type Voronoï et de types structurés redécoupés utilisant la technique AMA (Anisotropic Mesh Adapatation). Les conditions aux limites retenues sont principalement de type Dirichlet et de type Neumann. Pour aller au-delà des aspects utilisateurs et avoir une parfaite maîtrise du logiciel utilisé (seuls gages d’une bonne analyse des contenus physiques et mathématiques des outils CFD), un logiciel CFD baptisé MERLIN a été intégralement développé. Il contient toutes les équations, techniques, modèles et méthodes sélectionnés préalablement et a été utilisé pour l’ensemble des simulations numériques effectuées dans cette thèse. Afin d’assurer la fiabilité des expériences réalisées avec MERLIN, sa vérification a été effectuée en utilisant la méthode MMS (The Method of Manufactured Solutions). Pour comprendre la représentation numérique des phénomènes physiques associés au phénomène de l’explosion, on a dans un premier temps réalisé une étude portant sur la propagation d’onde de choc dans différentes configurations (cas subsonique du problème du tube à choc, réflexion d’un choc instationnaire sur une rampe compression, écoulement supersonique sur une marche montante). Il en résulte que la précision d’une prédiction numérique d’onde de choc dépend du schéma numérique et du type de maillage utilisés. Le choix du schéma numérique et du type de maillage dépend du type d’onde de choc à simuler numériquement. La seconde étude réalisée a consisté à simuler la dispersion de gaz
Emission of intermediate, semi and low volatile organic compounds from traffic and their impact on secondary organic aerosol concentrations over Greater Paris
No full textInternational audienceExhaust particle emissions are mostly made of black carbon and/or organic compounds, with some of these organic compounds existing in both the gas and particle phases. Although emissions of volatile organic compounds (VOC) are usually measured at the exhaust, emissions in the gas phase of lower volatility compounds (POAvapor) are not. However, these gas-phase emissions may be oxidised after emission and enhance the formation of secondary organic aerosols (SOA). They are shown here to contribute to most of the SOA formation in Central Paris. POAvapor emissions are usually estimated from primary organic aerosol emissions in the particle phase (POA). However, they could also be estimated from VOC emissions for both gasoline and diesel vehicles using previously published measurements from chamber measurements. Estimating POAvapor from VOC emissions and ageing exhaust emissions with a simple model included in the Polyphemus air-quality platform compare well to measurements of SOA formation performed in chamber experiments. Over Greater Paris, POAvapor emissions estimated using POA and VOC emissions are compared using the HEAVEN bottom-up traffic emissions model. The impact on the simulated atmospheric concentrations is then assessed using the Polyphemus/Polair3D chemistry-transport model. Estimating POAvapor emissions from VOC emissions rather than POA emissions lead to lower emissions along motorway axes (between −50% and −70%) and larger emissions in urban areas (up to between +120% and +140% in Central Paris). The impact on total organic aerosol concentrations (gas plus particle) is lower than the impact on emissions: between −8% and 25% along motorway axes and in urban areas respectively. Particle-phase organic concentrations are lower when POAvapor emissions are estimated from VOC than POA emissions, even in Central Paris where the total organic aerosol concentration is higher, because of different assumptions on the emission volatility distribution, stressing the importance of characterizing not only the emission strength, but also the emission volatility distribution
Applying a Global Sensitivity Analysis Workflow to Improve the Computational Efficiencies in Physiologically-Based Pharmacokinetic Modeling
No full textInternational audienceTraditionally, the solution to reduce parameter dimensionality in a physiologically-based pharmacokinetic (PBPK) model is through expert judgment. However, this approach may lead to bias in parameter estimates and model predictions if important parameters are fixed at uncertain or inappropriate values. The purpose of this study was to explore the application of global sensitivity analysis (GSA) to ascertain which parameters in the PBPK model are non-influential, and therefore can be assigned fixed values in Bayesian parameter estimation with minimal bias. We compared the elementary effect-based Morris method and three variance-based Sobol indices in their ability to distinguish "influential" parameters to be estimated and "non-influential" parameters to be fixed. We illustrated this approach using a published human PBPK model for acetaminophen (APAP) and its two primary metabolites APAP-glucuronide and APAP-sulfate. We first applied GSA to the original published model, comparing Bayesian model calibration results using all the 21 originally calibrated model parameters (OMP, determined by "expert judgment"-based approach) vs. the subset of original influential parameters (OIP, determined by GSA from the OMP). We then applied GSA to all the PBPK parameters, including those fixed in the published model, comparing the model calibration results using this full set of 58 model parameters (FMP) vs. the full set influential parameters (FIP, determined by GSA from FMP). We also examined the impact of different cut-off points to distinguish the influential and non-influential parameters. We found that Sobol indices calculated by eFAST provided the best combination of reliability (consistency with other variance-based methods) and efficiency (lowest computational cost to achieve convergence) in identifying influential parameters. We identified several originally calibrated parameters that were not influential, and could be fixed to improve computational efficiency without discernable changes in prediction accuracy or precision. We further found six previously fixed parameters that were actually influential to the model predictions. Adding these additional influential parameters improved the model performance beyond that of the original publication while maintaining similar computational efficiency. We conclude that GSA provides an objective, transparent, and reproducible approach to improve the performance and computational efficiency of PBPK models
Biosourced polymetallic catalysis : a surprising and efficient means to promote the Knoevenagel condensation
No full textInternational audienceZn hyperaccumulator (Arabidobsis halleri) and Zn accumulator Salix "Tordis" (Salix schwerinii x Salix viminalis) have shown their interest in the phytoextraction of polluted brownfields. Herein, we explore a novel methodology based on the chemical valorization of Zn-rich biomass produced by thesemetallophyte plants. The approach is based on the use of polymetallic salts derived from plants as bio-based catalysts in organic chemistry. The formed ecocatalysts were characterized via ICP-MS, X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR) in order to precise the chemical composition, structure, and behavior of the formed materials. The Doebner-Knoevenagel reaction was chosen as model reaction to study their synthetic potential. Significant differences to usual catalysts such as zinc (II) chloride are observed. They can principally be related to a mixture of unusual mineral species. DFT calculations were carried out on these salts in the context of the Gutmann theory. They allow the rationalization of experimental results. Finally, these new bio-based polymetallic catalysts illustrated the interest of this concept for green and sustainable catalysis
A guide to nanosafety testing : Considerations on cytotoxicity testing in different cell models
No full textInternational audienceSafety testing of nanoparticles (NPs) relies on robust, predictive, and reproducible methods. Integrated test strategies usually start with the assessment of in vitro cytotoxicity. Methods for this purpose are only partially established for NPs. The aim of this study was to evaluate three cytotoxicity assays for their applicability to NPs in several human cell models representing the most important NP target organs and to compare cell responses. The assays covered different biological principles, i.e. ATP content, redox metabolism, and membrane permeability, as well as different read-out principles, i.e. luminescence, colorimetry, and fluorescence. For all assays standard operating procedures were developed. A549 and NCI-H441 lung epithelial cells in single and in co-culture with THP-1 derived macrophages served as lung epithelial models. Normal human epidermal keratinocytes and in vitro reconstituted human epidermis were employed as skin models. Undifferentiated and differentiated Caco-2 gut epithelial cells were applied as gut epithelial models. Primary CD34-derived dendritic cells (CD34-DCs) served as an immune model. We used well-characterized model NPs, i.e. 50 nm amine-modified and 50 nm carboxyl-modified polystyrene NPs (PS-NH2 and PS-COOH, respectively). PS-COOH NPs showed no effect in any test while PS-NH2 displayed cytotoxicity in most cell models. CD34-DCs was the most sensitive cell model tested. The tetrazolium-based MTS assay was the most robust assay in our study, applicable to all cell models investigated. Therefore, this assay could become an integral part of a NP testing strategy. Other assays might be also useful, depending on the cell model or the type of investigation
Monitoring and numerical modelling of induced and triggered seismic activity in a deep sublevel-stoping mine
No full textInternational audienceThe Garpenberg undergroung mine (Sweden) is a non-ferrous metal mine, owned by Boliden company. It is exploiting lead, zinc and copper, together with minor amounts of silver and gold. The study area of the ongoing research work is part of the Lappberget orebody: an almost vertical deposit, which is mainly exploited by the sublevel stoping method, with backfilling, down to 1300 meters depth. A microseismic monitoring network, constituted by both 1-component and 3-components geophones, was installed in this area of the mine in the end of 2014 by Ineris. Recorded microseismic activity until December 2016 shows a good correlation with mining excavations, but also triggered seismic events, which are influenced by the presence of weak rock lenses within the stiff rock masses. A 3D elasto-plastic numerical model was run with the code FALC-3D, considering a precise reconstruction of the geology, the virgin stress state and the mine voids. The model takes into account 70 excavation steps, which correspond to the drifts developed and the stopes produced in the study area between 2014 and 2016. The results show how the mining sequence, with one column of stopes being exploited upwards and downwards simultaneously, leads to high stress concentrations and to strong plastic deformation within the weak rocks. Finally, we investigated possible statistical correlation between observed microseismic data (moment magnitude, seismic energy and corner frequency) and computed mechanical parameters (elastic and plastic deformation increments, Von-Mises stress jumps, released energy, etc.) by means of principal component analysis, helping to identify and analyze possible seismicity-triggering phenomena
Strengths and weaknesses of the FAIRMODE benchmarking methodology for the evaluation of air quality models
No full textInternational audienceThe Forum of Air Quality Modelling in Europe (FAIRMODE) was launched in 2007 to bring together air quality modellers and users in order to promote and support the harmonised use of models by EU Member States, with emphasis on model application under the European Air Quality Directive. In this context, a methodology for evaluating air quality model applications has been developed. This paper presents an analysis of the strengths and weaknesses of the FAIRMODE benchmarking approach, based on users' feedback. European wide, regional and urban scale model applications, developed by different research groups over Europe, have been taken into account. The analysis is focused on the main pollutants under the Air Quality Directive, namely PM10, NO2 and 0(3). The different case studies are described and analysed with respect to the methodologies applied for model evaluation and quality assurance. This model evaluation intercomparison demonstrates the potential of a harmonised evaluation and benchmarking methodology. A SWOT analysis of the FAIRMODE benchmarking approach is performed based on feedback from users of the tool. This analysis helps to identify the main advantages and value of this model evaluation benchmarking approach compared with other methodologies, in addition to highlighting requirements for future development
Modelling concentrations and properties of secondary aerosols in the Western Mediterranean
No full textInternational audienceThe Mediterranean basin is among one of the areas that can be most sensitive to climate change (Giorgi et al, 2006). This fact, along with the population density around this basin, the high burden in aerosol concentration that the basin experiences throughout the year and the increasing projections for shipping emissions in the future make it an important area to explore. While the organic aerosol can have an important impact on the local and also the regional air quality presently and in the future, the simulation of this aerosol in the western part of the Mediterranean basin is a subject that has not been studied thoroughly for present conditions and has been studied even less for the future. The present work consists of two phases. The first phase explores existing climatic runs performed with CHIMERE chemistry transport model with climate inputs corresponding to RCP2.6, RCP4.5 and RCP8.5 during the French PRIMEQUAL Salut’air project; with a focus on the Mediterranean basin and the changes that these scenarios induce in the concentration of particulate matter and especially organic aerosols. The effects of boundary conditions, and anthropogenic emission changes are assessed. Major driving climate variables affecting organic and fine aerosol levels over the basin are identified. During the second phase, sensitivity runs of the RCP4.5 scenario are performed, in which three different aerosol models are used, including a VBS scheme with and without biogenic aging (Robinson et al. 2007, Lane et al. 2008), and a modified VBS scheme containing fragmentation and formation of non-volatile organic aerosols (Shrivastava et al., 2013). These schemes have been previously compared to measurements obtained during the MISTRAL / CHARMEX summer 2013 campaign (Cholakian, 2017, in preparation). 10 years of historic and years 10 future runs have been performed, and a specific method allows chosing years maximizing the temperature and organic aerosol differences between past and future runs. This allows assessing the climate sensitivity of different organic aerosol schemes. This is a new and complex topic, as organic aerosol formation depends on several parameters (temperature playing on biogenic VOC emissions and phase partition of semi-volatile compounds, winds impacting advection, and precipitation impacting aerosol removal) and their representation in a model