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5. Unraveling the Roles of Saltation Bombardment and Atmospheric Instability on Magnitude and Size Distribution of Dust Emission Fluxes: Lessons From the JADE and WIND-O-V Experiments

Author

Alfaro, S. C., Bouet, C., Khalfallah, B., Shao, Y., Ishizuka, M., Labiadh, M., Marticorena, B., Laurent, B., Rajot, J. L., Alfaro, S. C., Bouet, C., Khalfallah, B., Shao, Y., Ishizuka, M., Labiadh, M., Marticorena, B., Laurent, B., and Rajot, J. L.

Abstract

The size distribution of the vertical flux of dust freshly emitted from a wind-eroded surface was recently shown to depend on the thermal stratification of the surface boundary layer (SBL). These new results question the way dust emission is currently represented in the dust models and emphasize the need to identify the factors controlling the intensity and size-resolved dust flux at emission. In this study, we re-analyze the data of two major campaigns (JADE and WIND-O-V) performed on unvegetated plots and during which the characteristics of the (a) surface of the eroding fields, (b) aerodynamic conditions (wind speed, stability of the SBL), (c) saltation flux (intensity and size distribution), and (d) vertical dust flux (intensity and size distribution) determined by the gradient method were carefully documented. The magnitude and size distribution of the vertical dust flux are found to be deeply intertwined and to be controlled in the first place by the kinetic energy of the saltating sand grains, and to a lesser extent by the size-dependent uplift of the sandblasted particles. In unstable conditions coarser sand grains are mobilized, which increases the kinetic energy of the saltation flux and leads to the production of finer particles by sandblasting. Conversely, the uplift of supermicron particles is facilitated by the increase of the wind friction velocity, which results in an enrichment of the vertical dust flux in the coarsest particles at large wind speeds. The implications of these new findings are particularly important for the modeling of the dust emission/transport/deposition cycle.

Published
2022

6. Comparison between Eddy-Covariance and Flux-Gradient size-resolved dust fluxes during wind erosion events

Author

Dupont, Sylvain, Rajot, J-L, Lamaud, E, Bergametti, G, Labiadh, M, Khalfallah, B, Bouet, C, Marticorena, B, Fernandes, R, Laboratoire Interuniversitaire des Systèmes Atmosphériques (LISA (UMR_7583)), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Est Créteil Val-de-Marne - Paris 12 (UPEC UP12)-Centre National de la Recherche Scientifique (CNRS)-Université de Paris (UP), and Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Est Créteil Val-de-Marne - Paris 12 (UPEC UP12)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité)

Subjects
[SDU]Sciences of the Universe [physics], [SDE]Environmental Sciences
Abstract

International audience; Estimating accurately dust emission flux during aeolian erosion events is crucial forquantifying the amount of dust in the atmosphere. The rare existing field experiments quantifyingsuch flux were mainly performed using the flux-gradient (FG) method. Here, we present the firstintercomparison of the size-resolved dust fluxes estimated by both the FG and the eddy-covariance (EC)methods during several erosion events. Both methods were applied simultaneously during the WINDO-V (WIND erOsion in presence of sparse Vegetation)'s 2017 field experiment over an isolated erodiblebare plot in South Tunisia. Overall, both methods predict similar dust fluxes for particle smaller thanabout 4 μm. For coarser particles, the EC method predicts a smaller dust flux than the FG method. Factorsexplaining this difference are discussed such as the different sampling heads used by the dust particlecounters of both methods, or the possible weakening of the constant dust flux layer at the location ofthe upper dust particle counter of the FG method. This intercomparison highlights the difficulties andadvantages of each method as well as their complementarity.

Published
2021

8. LA STABILITÉ ATMOSPHÉRIQUE INFLUENCE-T-ELLE LA DISTRIBUTION EN TAILLE DU FLUX VERTICAL DE POUSSIÈRE ? PREMIERS RÉSULTATS EN CONDITIONS D'ÉROSION

Author

B. KHALFALLAH, BOUET, C., LABIADH, M.T., ALFARO, S.C., BERGAMETTI, G., MARTICORENA, B., LAFON, S., CHEVAILLIER, S., FÉRON, A., HEASE, P., HENRY DES TUREAUX, T., SEKRAFI, S., ZAPF, P., and RAJOT, J.L.

Subjects
Érosion éolienne, Size-resolved dust flux, Atmospheric stability, Gradient method, Distribution en taille des aérosols désertiques, Stabilité atmosphérique, Wind erosion, Méthode du gradient
Abstract

La distribution en taille des aérosols désertiques est un élément-clef pour quantifier leurs impacts tout au long de leur cycle. Cependant, peu de mesures in-situ existent aujourd’hui pour caractériser cette propriété à l’émission. Ce travail présente les flux d’émission résolus en taille mesurés au cours de 8 événements érosifs dans le sud tunisien. La méthode employée est celle dite « du gradient ». Le principal résultat est qu’en condition d’érosion, la distribution en taille du flux vertical d’aérosols désertiques est plus riche en particules submicroniques pendant les périodes thermiquement instables., The size distribution of desert dust is a key factor to quantify its impacts during its life cycle. However, only a few in-situ measurements are currently available to document this feature at emission. This study presents the measurements of the size-distribution of the dust emission flux made during 8 erosive events using the gradient method over an experimental plot located in southern Tunisia. The main result is that in eroding conditions the number size-distribution of the dust flux is significantly enriched in submicron particles during thermally unstable periods.

Published
2020
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9. Influence of Atmospheric Stability on the Size Distribution of the Vertical Dust Flux Measured in Eroding Conditions Over a Flat Bare Sandy Field

Author

Khalfallah, B., primary, Bouet, C., additional, Labiadh, M.T., additional, Alfaro, S.C., additional, Bergametti, G., additional, Marticorena, B., additional, Lafon, S., additional, Chevaillier, S., additional, Féron, A., additional, Hease, P., additional, Henry des Tureaux, T., additional, Sekrafi, S., additional, Zapf, P., additional, and Rajot, J.L., additional

Published
2020
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10. Dissimilarity between dust, heat, and momentum turbulent transports during aeolian soil erosion

Author

Dupont, S., Rajot, J.-L, Labiadh, M., Bergametti, G., Lamaud, E., Irvine, M., Alfaro, S., Bouet, C., Fernandes, R., Khalfallah, B., Marticoréna, B., Bonnefond, J., Chevaillier, S., Garrigou, D., Henry-Des-Tureaux, T, Sekrafi, S., Zapf, P., Rajot, J.‐L., Henry‐des‐Tureaux, T., Interactions Sol Plante Atmosphère (UMR ISPA), Institut National de la Recherche Agronomique (INRA)-Ecole Nationale Supérieure des Sciences Agronomiques de Bordeaux-Aquitaine (Bordeaux Sciences Agro), Laboratoire Interuniversitaire des Systèmes Atmosphériques (LISA (UMR_7583)), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Est Créteil Val-de-Marne - Paris 12 (UPEC UP12)-Centre National de la Recherche Scientifique (CNRS)-Université de Paris (UP), Institut d'écologie et des sciences de l'environnement de Paris (iEES Paris ), Institut de Recherche pour le Développement (IRD)-Sorbonne Université (SU)-Université Paris-Est Créteil Val-de-Marne - Paris 12 (UPEC UP12)-Centre National de la Recherche Scientifique (CNRS)-Université de Paris (UP)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE), Institut des Régions Arides (IRA), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris Diderot - Paris 7 (UPD7)-Université Paris-Est Créteil Val-de-Marne - Paris 12 (UPEC UP12)-Centre National de la Recherche Scientifique (CNRS), ANR WIND-O-V, Institut d’Électronique, de Microélectronique et de Nanotechnologie (IEMN) - UMR 8520 (IEMN), Centre National de la Recherche Scientifique (CNRS)-Université de Lille-Université Polytechnique Hauts-de-France (UPHF)-Ecole Centrale de Lille-Université Polytechnique Hauts-de-France (UPHF)-Institut supérieur de l'électronique et du numérique (ISEN), Institut des Régions Arides de Médenine (IRA), Université Paris-Est Créteil Val-de-Marne - Paris 12 (UPEC UP12)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Unité de bioclimatologie, Institut National de la Recherche Agronomique (INRA), Écologie fonctionnelle et physique de l'environnement (EPHYSE - UR1263), Laboratoire de Météorologie Physique - Clermont Auvergne (LaMP), Institut national des sciences de l'Univers (INSU - CNRS)-Université Clermont Auvergne (UCA)-Centre National de la Recherche Scientifique (CNRS), Institut Pluridisciplinaire Hubert Curien (IPHC), Centre National de la Recherche Scientifique (CNRS)-Université de Strasbourg (UNISTRA), Interactions Sol Plante Atmosphère (ISPA), Ecole Nationale Supérieure des Sciences Agronomiques de Bordeaux-Aquitaine (Bordeaux Sciences Agro)-Institut National de la Recherche Agronomique (INRA), Institut d'écologie et des sciences de l'environnement de Paris (IEES (UMR_7618 / UMR_D_242 / UMR_A_1392 / UM_113) ), Institut National de la Recherche Agronomique (INRA)-Sorbonne Université (SU)-Université Paris-Est Créteil Val-de-Marne - Paris 12 (UPEC UP12)-Centre National de la Recherche Scientifique (CNRS), Centre National de la Recherche Scientifique (CNRS)-Université Paris Diderot - Paris 7 (UPD7)-Université Paris-Est Créteil Val-de-Marne - Paris 12 (UPEC UP12)-Institut national des sciences de l'Univers (INSU - CNRS), Groupe de Recherche en Informatique, Image, Automatique et Instrumentation de Caen (GREYC), Université de Caen Normandie (UNICAEN), Normandie Université (NU)-Normandie Université (NU)-École Nationale Supérieure d'Ingénieurs de Caen (ENSICAEN), Normandie Université (NU)-Centre National de la Recherche Scientifique (CNRS), Laboratoire de recherche en Hydrodynamique, Énergétique et Environnement Atmosphérique (LHEEA), École Centrale de Nantes (ECN)-Centre National de la Recherche Scientifique (CNRS), Université de Strasbourg (UNISTRA)-Centre National de la Recherche Scientifique (CNRS), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Est Créteil Val-de-Marne - Paris 12 (UPEC UP12)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité), and Institut de Recherche pour le Développement (IRD)-Sorbonne Université (SU)-Université Paris-Est Créteil Val-de-Marne - Paris 12 (UPEC UP12)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)

Subjects
Atmospheric Science, 010504 meteorology & atmospheric sciences, Astrophysics::High Energy Astrophysical Phenomena, Eddy covariance, Astrophysics::Cosmology and Extragalactic Astrophysics, Atmospheric sciences, 01 natural sciences, law.invention, TUNISIA, Flux (metallurgy), law, Intermittency, Saltation (geology), Earth and Planetary Sciences (miscellaneous), Astrophysics::Solar and Stellar Astrophysics, [SDU.ENVI]Sciences of the Universe [physics]/Continental interfaces, environment, ComputingMilieux_MISCELLANEOUS, Astrophysics::Galaxy Astrophysics, 0105 earth and related environmental sciences, [PHYS]Physics [physics], [SDU.OCEAN]Sciences of the Universe [physics]/Ocean, Atmosphere, SEMIARID AREA, Turbulence, 15. Life on land, Geophysics, Heat flux, 13. Climate action, Space and Planetary Science, [SDU]Sciences of the Universe [physics], [SDE]Environmental Sciences, Erosion, Aeolian processes, Environmental science, Astrophysics::Earth and Planetary Astrophysics, 068, 020
Abstract

International audience; Measuring accurately size-resolved dust flux near the surface is crucial for better quantifying dust losses by semiarid soils. Dust fluxes have been usually estimated from the flux-gradient approach, assuming similarity between dust and momentum turbulent transport. This similarity has, however, never been verified. Here we investigate the similarity between dust (0.3 to 6.0 m in diameter), momentum, and heat fluxes during aeolian erosion events. These three fluxes were measured by the Eddy Covariance technique during the WIND-O-V (WIND erOsion in presence of sparse Vegetation's) 2017 field experiment over an isolated erodible bare plot in South Tunisia. Our measurements confirm the prevalence of ejection and sweep motions in transporting dust as for heat and momentum. However, our measurements also reveal a different partition of the dust flux between ejection and sweep motions and between eddy time scales compared to that of momentum and heat fluxes. This dissimilarity results from the intermittency of the dust emission compared to the more continuous emission (absorption) of heat (momentum) at the surface. Unlike heat emission and momentum absorption, dust release is conditioned by the wind intensity to initiate sandblasting. Consequently, ejection motions do not carry dust as often as heat and low momentum from the surface. This dissimilarity diminishes with increasing wind intensity as saltation patterns, and thus dust emission through sandblasting, become spatially more frequent. Overall, these findings may have implications on the evaluation of dust flux from techniques based on similarity with momentum or heat turbulent transport.

Published
2019

11. Characterization of Lactococcus lactis phage antigens

Author

Schouler, C., Bouet, C., Ritzenthaler, P., Drouet, X., and Mata, M.

Subjects
Bacteriophages -- Physiological aspects, Genetic engineering -- Usage, Biological sciences
Abstract

Antigens of lactococcal phage phi197 were identified and characterized using DNA recombination, cloning and hybridization. Three antigens were identified, two of them being conformational epitopes. Plasmid pOA17 coded for a hybrid protein which was used to induce antibody formation. The antibodies against this protein were used to identify a 46-kDa minor phage protein which provided the third epitope. This epitope was resistant to denaturation and was very immunogenic. Antibody cross-reactivity with other related phages proved that this epitope is highly conserved.

Published
1992

12. Aerodynamic Parameters Over an Eroding Bare Surface: Reconciliation of the Law of the Wall and Eddy Covariance Determinations

Author

Dupont, S., Rajot, J-L, Labiadh, M., Bergametti, G., Alfaro, S., Bouet, C., Fernandes, R., Khalfallah, B., Lamaud, E., Marticoréna, B., Bonnefond, J-M, Chevaillier, S., Garrigou, D., Henry-des-Tureaux, T., Sekrafi, S., Zapf, P., Rajot, J-L., Bonnefond, J-M., Interactions Sol Plante Atmosphère (ISPA), Institut National de la Recherche Agronomique (INRA)-Ecole Nationale Supérieure des Sciences Agronomiques de Bordeaux-Aquitaine (Bordeaux Sciences Agro), Institut d'écologie et des sciences de l'environnement de Paris (IEES (UMR_7618 / UMR_D_242 / UMR_A_1392 / UM_113) ), Institut National de la Recherche Agronomique (INRA)-Sorbonne Université (SU)-Université Paris-Est Créteil Val-de-Marne - Paris 12 (UPEC UP12)-Centre National de la Recherche Scientifique (CNRS), Institut des Régions Arides de Médenine (IRA), Laboratoire Interuniversitaire des Systèmes Atmosphériques (LISA (UMR_7583)), Centre National de la Recherche Scientifique (CNRS)-Université Paris Diderot - Paris 7 (UPD7)-Université Paris-Est Créteil Val-de-Marne - Paris 12 (UPEC UP12)-Institut national des sciences de l'Univers (INSU - CNRS), Institut d’Électronique, de Microélectronique et de Nanotechnologie (IEMN) - UMR 8520 (IEMN), Centre National de la Recherche Scientifique (CNRS)-Université de Lille-Université Polytechnique Hauts-de-France (UPHF)-Ecole Centrale de Lille-Université Polytechnique Hauts-de-France (UPHF)-Institut supérieur de l'électronique et du numérique (ISEN), Université Paris-Est Créteil Val-de-Marne - Paris 12 (UPEC UP12)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Laboratoire de Météorologie Physique - Clermont Auvergne (LaMP), Institut national des sciences de l'Univers (INSU - CNRS)-Université Clermont Auvergne (UCA)-Centre National de la Recherche Scientifique (CNRS), Institut Pluridisciplinaire Hubert Curien (IPHC), Centre National de la Recherche Scientifique (CNRS)-Université de Strasbourg (UNISTRA), Unité de bioclimatologie, Institut National de la Recherche Agronomique (INRA), IWMI-SFRI, Institut de Recherche pour le Développement (IRD [Nouvelle-Calédonie]), Interactions Sol Plante Atmosphère (UMR ISPA), Institut des Régions Arides (IRA), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris Diderot - Paris 7 (UPD7)-Université Paris-Est Créteil Val-de-Marne - Paris 12 (UPEC UP12)-Centre National de la Recherche Scientifique (CNRS), Institut d'écologie et des sciences de l'environnement de Paris (iEES Paris ), Institut de Recherche pour le Développement (IRD)-Sorbonne Université (SU)-Université Paris-Est Créteil Val-de-Marne - Paris 12 (UPEC UP12)-Centre National de la Recherche Scientifique (CNRS)-Université de Paris (UP)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Est Créteil Val-de-Marne - Paris 12 (UPEC UP12)-Centre National de la Recherche Scientifique (CNRS)-Université de Paris (UP), Laboratoire de recherche en Hydrodynamique, Énergétique et Environnement Atmosphérique (LHEEA), École Centrale de Nantes (ECN)-Centre National de la Recherche Scientifique (CNRS), Lieux, Identités, eSpaces, Activités (LISA), Centre National de la Recherche Scientifique (CNRS)-Université Pascal Paoli (UPP), Université de Strasbourg (UNISTRA)-Centre National de la Recherche Scientifique (CNRS), Institut de Recherche pour le Développement (IRD)-Sorbonne Université (SU)-Université Paris-Est Créteil Val-de-Marne - Paris 12 (UPEC UP12)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Est Créteil Val-de-Marne - Paris 12 (UPEC UP12)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité), and Université Pascal Paoli (UPP)-Centre National de la Recherche Scientifique (CNRS)

Subjects
Atmospheric Science, 010504 meteorology & atmospheric sciences, Eddy covariance, Von Kármán constant, 01 natural sciences, Law of the wall, Wind speed, 010305 fluids & plasmas, Saltation (geology), 0103 physical sciences, Earth and Planetary Sciences (miscellaneous), Surface roughness, Shear velocity, [SDU.ENVI]Sciences of the Universe [physics]/Continental interfaces, environment, ComputingMilieux_MISCELLANEOUS, 0105 earth and related environmental sciences, [SDU.OCEAN]Sciences of the Universe [physics]/Ocean, Atmosphere, [PHYS]Physics [physics], Mechanics, 021, 020, 068, Geophysics, Space and Planetary Science, [SDU]Sciences of the Universe [physics], [SDE]Environmental Sciences, Aeolian processes, Geology
Abstract

International audience; Assessing accurately the surface friction velocity is a key issue for predicting and quantifying aeolian soil erosion. This is usually done either indirectly from the law of the wall (LoW) of the mean wind velocity profile or directly from eddy covariance (EC) of the streamwise and vertical wind velocity fluctuations. However, several recent experiments have reported inconsistency between friction velocities deduced from both methods. Here we reinvestigate the determination of aerodynamic parameters (friction velocity and surface roughness length) over an eroding bare surface and look at the possible reasons for observing differences on these parameters following the method. For that purpose a novel field experiment was performed in South Tunisia under the research program WIND-O-V (WIND erOsion in presence of sparse Vegetation). We find no significant difference between friction velocities obtained from both law of the wall and EC approaches when the friction velocity deduced from the EC method was extrapolated to the surface. Surface roughness lengths show a clear increase with wind erosion, with more scattered values when deduced from the EC friction velocity. Our measurements further suggest an average value of the von Karman constant of 0.407±0.002, although individual wind events lead to different average values due probably to the definition of the ground level or to the stability correction. Importantly, the von Karman constant was found independent of the wind intensity and thus of the wind soil erosion intensity. Finally, our results lead to several recommendations for estimating the aerodynamic parameters over bare surface in order to evaluate saltation and dust fluxes.

Published
2018

13. Towards the Mass Production of High Efficiency Passivated Contacts n-Type PERT Solar Cells

Author

Martel, B., Yang, J., Loretz, J.C., Tran, S., Blevin, T., and Bouet, C.

Subjects
Manufacturing & Production of Si Cells, Silicon Cells
Abstract

35th European Photovoltaic Solar Energy Conference and Exhibition; 832-834, In this work, we intent to elaborate a rear side passivated contact n-PERT solar cell structure using high throughput industrial equipment in a cost-effective manner. The passivation of the metal contact, and the charge transport on the rear side are ensured by a thin silicon oxide layer (

Published
2018
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16. How long does precipitation inhibit wind erosion in the Sahel?

Author

Bergametti, G., Rajot, J., Pierre, Caroline, Bouet, C., Marticorena, B., Laboratoire Interuniversitaire des Systèmes Atmosphériques (LISA (UMR_7583)), Université Paris-Est Créteil Val-de-Marne - Paris 12 (UPEC UP12)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris Diderot - Paris 7 (UPD7)-Université Paris-Est Créteil Val-de-Marne - Paris 12 (UPEC UP12)-Centre National de la Recherche Scientifique (CNRS), European Community, French Agence Nationale de la Recherche (ANR) [ANR-12-SENV-0007-01, ANR ASTRID 2012], Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Est Créteil Val-de-Marne - Paris 12 (UPEC UP12)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité), Institut d'écologie et des sciences de l'environnement de Paris (iEES Paris ), and Institut de Recherche pour le Développement (IRD)-Sorbonne Université (SU)-Université Paris-Est Créteil Val-de-Marne - Paris 12 (UPEC UP12)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)

Subjects
[SDE.MCG]Environmental Sciences/Global Changes, [SDE]Environmental Sciences
Abstract

International audience; Simultaneous measurements of saltation, wind speed, and rainfall performed in Niger before, during, and after 18 rain events are used to investigate how rain events affect wind erosion in the Sahel. The results show that the inhibition of saltation is rapid but progressive after the beginning of a rain event. The decrease of sand transport during the rain event is better linked to the time elapsed from the beginning of the rain event rather than to the cumulative rainfall. In the Sahel, after a rain event, less than 12 h is necessary to almost fully restore the sand transport potential. Our results suggest that assuming that no sand transport and dust emission occur during the 12 h following the end of a rain event could be a reasonable alternative to existing parameterizations of the influence of soil moisture on the wind erosion threshold, at least for the Sahelian conditions.

Published
2016

17. Impact of Climate, Agriculture and Vegetation in the Sahel in the recent past : the CAVIARS Projet. [P-3330-53]

Author

Marticorena, Béatrice, Abdourhamane Touré, Amadou, Baron, Christian, Bergametti, Gilles, Bouet, C., Bouniol, D., Campos, A., Couvreux, F., Dardel, C., Guichard, Françoise, Grippa, Manuela, Hiernaux, Pierre, Kergoat, Laurent, Largeron, Y., Lebel, Thierry, Mougin, Eric, Pennanech, C., Pierre, Caroline, Quantin, G., Rajot, J.L., Siour, G., Tidjani, A.D., Valentin, C., and Vischel, T.

Subjects
U10 - Méthodes mathématiques et statistiques, P40 - Météorologie et climatologie, A01 - Agriculture - Considérations générales, P36 - Erosion, conservation et récupération des sols
Abstract

The semi-arid regions of the Earth are particularly vulnerable to wind erosion. The Sahelian region experienced contrasted climatic conditions during the last decades, with severe drought in the 70's and 80's and a relative re-greening in the recent years. Over the same period, changes in land use have occurred with an increase of the cultivated surfaces leading to a decrease of fallows and rangelands. As a result, a significant proportion of the land is bare or sparsely vegetated, and thus is not efficiently protected from the erosive action of wind. In this region, wind erosion tends to decrease the productive capacity of the soils whose fertility is already very low. In addition, the impact of wind erosion is expected to increase significantly in the near future (1) in relation with the expected changes in climate (in particular the modifications of precipitation and surface wind) and (2) in response to the increasing land use due to population increase and the related food needs. The aims of the CAVIARS project (Climate, Agriculture and Vegetation: Impacts on Aeolian ERosion in the Sahel) are to develop an integrated modeling tool to describe the evolution of wind erosion in the Sahel in connection with climatic and land use changes, to validate this tool in the current period by making the best possible use of the numerous data sets acquired in recent years over West Africa, and to test its ability to reproduce specific events (such as the drought in the Sahel) of the recent past (about the last 50 years). This project is based on a modeling approach of this recent past (hindcasts) that is justified by the need to ensure the robustness of the simulations with different forcings prior to any simulation of future scenarios. The proposed strategy is (1) to develop or optimize reliable modeling tools for quantifying the various terms (land use, changes in aridity...) responsible for changes in the intensity of wind erosion (2) to synthesize quality checked observations, that can be used as direct or indirect indicators of wind erosion (precipitation time series, changes in vegetation cover, atmospheric dust load,...) (3) to implement a validation strategy based on the quantification of wind erosion both locally, measured on grazed and cultivated plots, and at the regional and continental scales. (Texte intégral)

Published
2015

19. Synthesis and Characterization of Near-Infrared Cu−In−Se/ZnS Core/Shell Quantum Dots for In vivo Imaging

Author

Cassette, E., Pons, T., Bouet, C., Helle, M., Bezdetnaya, L., Marchal, F., and Dubertret, B.

Abstract

Near-infrared (NIR) semiconductor quantum dots (QDs) represent promising fluorescent probes for biological and biomedical imaging. CuInSe2is a good candidate for these applications due to its bandgap in the near-infrared and the reduced toxicity of its components compared to other NIR QD materials (CdTe, CdHgTe, PbS, etc.). Here we present a simple one-pot synthetic route without injection to make fluorescent sphalerite Cu−In−Se core and Cu−In−Se/ZnS core/shell QDs. We show that the photoluminescence (PL) of the resulting core QDs can be tuned from ∼700 nm to ∼1 μm depending on the QD size (from ∼2 to ∼5 nm in diameter). The optical and structural properties of these QDs are consistent with charge recombination via donor−acceptor levels instead of direct excitonic recombination. Finally, we show that the growth of a ZnS shell around these QDs increases their PL quantum yield substantially (up to 40−50% at 800 nm) and allows preservation of their PL properties after solubilization into water and in vivo, as demonstrated by detection of the regional lymph node in a mouse.

Published
2024
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20. Impact of vegetation and soil moisture seasonal dynamics on dust emissions over the Sahel

Author

Pierre, C., Bergametti, G., Marticoréna, B., Mougin, E., Bouet, C., Schmechtig, C., Géosciences Environnement Toulouse (GET), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS), Laboratoire Interuniversitaire des Systèmes Atmosphériques (LISA (UMR_7583)), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Est Créteil Val-de-Marne - Paris 12 (UPEC UP12)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité), Biogéochimie et écologie des milieux continentaux (Bioemco), École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Institut de Recherche pour le Développement (IRD)-Institut National de la Recherche Agronomique (INRA)-Université Pierre et Marie Curie - Paris 6 (UPMC)-AgroParisTech-Centre National de la Recherche Scientifique (CNRS), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris Diderot - Paris 7 (UPD7)-Université Paris-Est Créteil Val-de-Marne - Paris 12 (UPEC UP12)-Centre National de la Recherche Scientifique (CNRS), Centre d'études spatiales de la biosphère (CESBIO), Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Université Toulouse III - Paul Sabatier (UT3), Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS), Laboratoire d'océanographie de Villefranche (LOV), Observatoire océanologique de Villefranche-sur-mer (OOVM), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS), Université Paris-Est Créteil Val-de-Marne - Paris 12 (UPEC UP12)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Observatoire Midi-Pyrénées (OMP), Université Fédérale Toulouse Midi-Pyrénées-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire océanologique de Villefranche-sur-mer (OOVM), and Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS)

Subjects
[SDU.OCEAN]Sciences of the Universe [physics]/Ocean, Atmosphere, VARIATION ANNUELLE, VARIATION SAISONNIERE, COUVERT VEGETAL, SURFACE DU SOL, [SDU]Sciences of the Universe [physics], HUMIDITE DU SOL, AEROSOL, [SDU.ENVI]Sciences of the Universe [physics]/Continental interfaces, environment, DESERT, MODELISATION, EROSION EOLIENNE
Abstract

International audience; [1] To address the challenging issue of estimating mineral dust emissions from the semi-arid Sahel, a modeling approach is developed by combining two specific models: one dedicated to the simulation of the seasonal herbaceous layer in the Sahel (STEP) and the other to the estimation of dust emissions (MB). The area of interest is the Sahelian belt (12 N-20 N, 20 W-35 E) and the simulations were performed at a 0.25 spatial resolution over a 4-year period (2004-2007). The rainfall forcing is provided by a TRMM (Tropical Rainfall Measuring Mission) satellite-derived product; the other meteorological data are ECMWF products. An empirical parameterization is used to estimate the surface roughness and its temporal dynamics according to the characteristics of the simulated vegetation in terms of surface cover and height. Where no vegetation grows, the surface properties are considered as constant in time and are derived from the POLDER-1 satellite measurements. Simulations are constrained step by step by comparisons with observations. Simulated annual dust fluxes emitted from the whole area range from approximately 100 Mt to 400 Mt depending on the year, in good agreement with previous works dealing with Saharan dust emissions. For the fringe where herbaceous vegetation can affect dust emissions, the annual dust emission fluxes range between 0.5 Mt and 20 Mt depending on the year. Inhibition of dust emissions due to the seasonal dynamics of vegetation and surface soil moisture over this fringe varies between 20% and 35%. Citation: Pierre, C., G. Bergametti, B. Marticorena, E. Mougin, C. Bouet, and C. Schmechtig (2012), Impact of vegetation and soil moisture seasonal dynamics on dust emissions over the Sahel

Published
2012

23. Quantifying uncertainty in estimates of mineral dust flux: An intercomparison of model performance over the Bodélé Depression, northern Chad

Author

Todd, M. C., primary, Bou Karam, D., additional, Cavazos, C., additional, Bouet, C., additional, Heinold, B., additional, Baldasano, J. M., additional, Cautenet, G., additional, Koren, I., additional, Perez, C., additional, Solmon, F., additional, Tegen, I., additional, Tulet, P., additional, Washington, R., additional, and Zakey, A., additional

Published
2008
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27. A comprehensive modelling way for assessing real-time mixings of mineral and anthropogenic pollutants in East Asia.

Author

Lasserre, F., Cautenet, G., Bouet, C., Dong, X., Kim, Y. J., Sugimoto, N., Matsui, I., and Shimizu, A.

Abstract

In order to assess the complex mixing of atmospheric anthropogenic and natural pollutants over the East Asian region, we propose to take into account the main aerosols simultaneously present over China, Korea and Japan during the spring season. With the mesoscale RAMS (Regional Atmospheric Modeling System) tool, we present a simulation of natural (desert) dust events along with some of the most critical anthropogenic pollutants over East Asia: sulphur elements (SO2 and SO42-) and Black Carbon (BC). During a 2-week case study of dust events which occurred in April 2005 over an area extending from the Gobi deserts to the Japan surroundings, we retrieve the behaviours of the different aerosols plumes. We focus on possible dust mixing with the anthropogenic pollutants from megalopolis. For both natural and anthropogenic pollution, the model results are in general agreement with the horizontal and vertical distributions of concentrations as measured by remote data, in situ LIDAR, PM10 data and literature. In particular, we show that a simplified chemistry approach of this complex issue can be efficient enough to model this event, with a real-time step of 3 h. The model provides the good shapes and orders of magnitude for the Aerosol Optical Thickness (AOT) and species contributions (via the Angström Exponent) when compared with the AERONET data. [ABSTRACT FROM AUTHOR]

Published
2007
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28. Synthesis and Molecular Structure of a Palladium Complex Containing a λ<SUP>5</SUP>-Phosphinine-Based SPS Pincer Ligand

Author

Doux, M., Bouet, C., Mezailles, N., Ricard, L., and Floch, P. Le

Abstract

2,6-Bis(diphenylphosphino)-3,5-diphenylphosphinine (1) reacts with elemental sulfur to yield the corresponding 2,6-bis(diphenylphosphine sulfide)-3,5-diphenylphosphinine (2). Reaction of ligand 2 with [Pd(COD)Cl2] affords the square planar complex 4 resulting from the displacement of one chloride ligand. An X-ray crystal study reveals that complex 4 features a λ4-1-P-chlorophosphinine ligand which is bound to the palladium atom through the phosphorus atom. Reaction of 4 with methanol gives the corresponding P−OMe complex resulting from the nucleophilic substitution of the P−Cl bond. DFT calculations suggest that the formation of 4 results from the internal attack of the chloride counteranion onto the highly electrophilic P atom of the transient λ3-phosphinine complex [Pd(2)Cl]+ (3).

Published
2002
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29. Il corpus Augustalium di Tergeste: una nuova testimonianza dalla revisione della tabula bronzea di InscrIt. X, 4, 29a

Author

Mainardis, Fulvia, A. Bouet, C. Petit-Aupert, and Mainardis, Fulvia

Subjects
storia romana, collegia, exemplum epistulae, Epigrafia latina
Abstract

Il contributo prende in esame una tabula bronzea fortemente frammentaria rinvenuta a Trieste ed edita già nelle Inscriptiones Italiane a cura di P. Sticotti nel 1951. La rilettura del testo permette di individuare la prima attestazione del corpus Augustalium di Tergeste menzionato in un probabile exemplum epistulae in cui sono nominati anche gli edili della città, probabilmente chiamati in causa per l'amministrazione di un bene legato a un atto evergetico opera di uno schiavo imperiale.

Published
2018

30. « Quand deux communautés de « frères » rentrent dans l'Ordre... La donation par Simon d'Ailly des chapelles d'Ailly et du Val-Boutry à l'abbaye de Saint-Pierre-sur-Dives à la fin du XVe siècle »

Author

Maneuvrier, Christophe, Arnoux, M., Centre Michel de Boüard - Centre de recherches archéologiques et historiques médiévales ( CRAHM ), Université de Caen Normandie ( UNICAEN ), Normandie Université ( NU ) -Normandie Université ( NU ) -Centre National de la Recherche Scientifique ( CNRS ), P. Bouet, C. Bougy, B. Garnier, et C. Maneuvrier (éd.), Centre Michel de Boüard - Centre de recherches archéologiques et historiques médiévales (CRAHM), Université de Caen Normandie (UNICAEN), Normandie Université (NU)-Normandie Université (NU)-Centre National de la Recherche Scientifique (CNRS), P. Bouet, C. Bougy, B. Garnier, et C. Maneuvrier (éd.), and Leroy-Hale, Marie-Noëlle

Subjects
[ SHS.HIST ] Humanities and Social Sciences/History, [SHS.HIST] Humanities and Social Sciences/History, [SHS.HIST]Humanities and Social Sciences/History
Published
2009

31. « Les Gesta Roberti Guiscardi de Guillaume de Pouille : études de quelques éléments épiques »

Author

Lucas-Avenel , Marie-Agnès, Centre Michel de Boüard - Centre de recherches archéologiques et historiques médiévales (CRAHM), Université de Caen Normandie (UNICAEN), Normandie Université (NU)-Normandie Université (NU)-Centre National de la Recherche Scientifique (CNRS), P. Bouet, C. Bougy, B. Garnier, C. Maneuvier (dir.), Leroy-Hale, Marie-Noëlle, P. Bouet, C. Bougy, B. Garnier, C. Maneuvier (dir.), Centre Michel de Boüard - Centre de recherches archéologiques et historiques médiévales ( CRAHM ), Université de Caen Normandie ( UNICAEN ), and Normandie Université ( NU ) -Normandie Université ( NU ) -Centre National de la Recherche Scientifique ( CNRS )

Subjects
[ SHS.HIST ] Humanities and Social Sciences/History, [SHS.HIST] Humanities and Social Sciences/History, [SHS.HIST]Humanities and Social Sciences/History
Published
2009

32. « Autour de l'année 1047 : un acte de Guillaume, comte d'Arques, pour l'abbaye de Fécamp (18 juillet 1047) »

Author

Bauduin , Pierre, Bates , David, Centre Michel de Boüard - Centre de recherches archéologiques et historiques médiévales ( CRAHM ), Université de Caen Normandie ( UNICAEN ), Normandie Université ( NU ) -Normandie Université ( NU ) -Centre National de la Recherche Scientifique ( CNRS ), P. Bouet, C. Bougy, B. Garnier, et C. Maneuvrier (éd.), Centre Michel de Boüard - Centre de recherches archéologiques et historiques médiévales (CRAHM), Université de Caen Normandie (UNICAEN), Normandie Université (NU)-Normandie Université (NU)-Centre National de la Recherche Scientifique (CNRS), Bouet, Pierre, Bougy, Catherine, Garnier, B., and Maneuvrier, Christophe

Subjects
[ SHS.HIST ] Humanities and Social Sciences/History, [SHS.HIST]Humanities and Social Sciences/History
Published
2009

33. ' Note sur l'orgue de Fécamp. Extrait de la lettre de Baudri de Bourgueil aux moines de Fécamp '

Author

Véronique Gazeau, Centre Michel de Boüard - Centre de recherches archéologiques et historiques médiévales (CRAHM), Université de Caen Normandie (UNICAEN), Normandie Université (NU)-Normandie Université (NU)-Centre National de la Recherche Scientifique (CNRS), P. Bouet, C. Bougy, B. Garnier et C. Maneuvrier (dir.), Centre Michel de Boüard - Centre de recherches archéologiques et historiques médiévales ( CRAHM ), Université de Caen Normandie ( UNICAEN ), Normandie Université ( NU ) -Normandie Université ( NU ) -Centre National de la Recherche Scientifique ( CNRS ), P. Bouet, C. Bougy, B. Garnier et C. Maneuvrier (dir.), and Leroy-Hale, Marie-Noëlle

Subjects
[ SHS.HIST ] Humanities and Social Sciences/History, [SHS.HIST] Humanities and Social Sciences/History, General Engineering, General Earth and Planetary Sciences, [SHS.HIST]Humanities and Social Sciences/History, General Environmental Science
Abstract

Gazeau Véronique. Note sur l'orgue de Fécamp. Extrait de la lettre de Baudri de Bourgueil aux moines de Fécamp. In: Cahier des Annales de Normandie n°35, 2009. De part et d'autre de la Normandie médiévale. Recueil d'études en hommage à François Neveux. pp. 347-351.

Published
2009

34. ' L'énigme des origines de l'abbaye de Montebourg : une question de méthode ? '

Author

Eric van Torhoudt, Centre Michel de Boüard - Centre de recherches archéologiques et historiques médiévales ( CRAHM ), Université de Caen Normandie ( UNICAEN ), Normandie Université ( NU ) -Normandie Université ( NU ) -Centre National de la Recherche Scientifique ( CNRS ), P. Bouet, C. Bougy, B. Garnier et C. Maneuvrier (dir.), Centre Michel de Boüard - Centre de recherches archéologiques et historiques médiévales (CRAHM), Centre National de la Recherche Scientifique (CNRS)-Université de Caen Normandie (UNICAEN), Normandie Université (NU)-Normandie Université (NU), P. Bouet, C. Bougy, B. Garnier et C. Maneuvrier (dir.), and Leroy-Hale, Marie-Noëlle

Subjects
[ SHS.HIST ] Humanities and Social Sciences/History, [SHS.HIST] Humanities and Social Sciences/History, General Engineering, General Earth and Planetary Sciences, [SHS.HIST]Humanities and Social Sciences/History, General Environmental Science
Abstract

Van Torhoudt Eric. L'« énigme » des origines de l'abbaye de Montebourg : une question de méthode ?. In: Cahier des Annales de Normandie n°35, 2009. De part et d'autre de la Normandie médiévale. Recueil d'études en hommage à François Neveux. pp. 331-346.

Published
2009

35. ' Le contrôle des clercs paroissiaux vu par les évêques normands (XIe-XIIe siècles) '

Author

Combalbert, Grégory, Centre Michel de Boüard - Centre de recherches archéologiques et historiques médiévales (CRAHM), Centre National de la Recherche Scientifique (CNRS)-Université de Caen Normandie (UNICAEN), Normandie Université (NU)-Normandie Université (NU), P. Bouet, C. Bougy, B. Garnier, et C. Maneuvrier (éd.), Leroy-Hale, Marie-Noëlle, P. Bouet, C. Bougy, B. Garnier, et C. Maneuvrier (éd.), Centre Michel de Boüard - Centre de recherches archéologiques et historiques anciennes et médiévales (CRAHAM), Université de Caen Normandie (UNICAEN), Normandie Université (NU)-Normandie Université (NU)-Centre National de la Recherche Scientifique (CNRS), Pierre Bouet, Catherine Bougy, Bernard Garnier, Christophe Maneuvrier, Combalbert, Grégory, and Pierre Bouet, Catherine Bougy, Bernard Garnier, Christophe Maneuvrier

Subjects
[SHS.HIST] Humanities and Social Sciences/History, [SHS.HIST]Humanities and Social Sciences/History, ComputingMilieux_MISCELLANEOUS
Abstract

International audience

Published
2009

36. Insights into the Formation Mechanism of CdSe Nanoplatelets Using in Situ X-ray Scattering.

Author

Castro N, Bouet C, Ithurria S, Lequeux N, Constantin D, Levitz P, Pontoni D, and Abécassis B

Abstract

Two-dimensional ultrathin CdSe nanoplatelets have attracted a large interest due to their optical properties but their formation mechanism is not well understood. Several different mechanisms have been proposed: confined growth in a surfactant mesophase acting as a template, anisotropic ripening of small seeds into 2D nanoplatelets, or continuous anisotropic growth of a limited number of nuclei. However, quantitative in situ data that could validate or disprove these formation scenarios are lacking. We use synchrotron-based small-angle and wide-angle X-ray scattering to probe the formation mechanism of CdSe nanoplatelets synthesized using a heating-up method. We prove the absence of a molecular mesophase in the reactive medium at the onset of nanoplatelet formation ruling out a templating effect. We also show that our data are inconsistent with the anisotropic ripening of small seeds whereas the evolution of the SAXS patterns during the reaction is consistent with the continuous lateral growth of nanoplatelets fed by reactive monomers. Finally, we show that when the final temperature of the synthesis is lowered, nanoplatelets with larger lateral dimensions form. We reveal that they bend in solution during their growth to yield nanoscrolls.

Published
2019
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37. Stacking and Colloidal Stability of CdSe Nanoplatelets.

Author

Jana S, Phan TN, Bouet C, Tessier MD, Davidson P, Dubertret B, and Abécassis B

Abstract

Colloidal CdSe nanoplatelets with monolayer control over their thickness can now be synthesized in solution and display interesting optical properties. From a fundamental point of view, the self-assembly of CdSe nanoplatelets can impact their optical properties through short-range interactions, and achieving control over their dispersion state in solution is of major relevance. The related issue of colloidal stability is important from an applicative standpoint in the perspective of the processing of these materials. Using UV-vis spectroscopy, we assess the colloidal stability of dispersions of CdSe nanoplatelets at different nanoparticle and ligand (oleic acid) concentrations. We unravel an optimum in oleic acid concentration for colloidal stability and show that even moderately concentrated dispersions flocculate on a time scale ranging from minutes to hours. Small-angle X-ray scattering shows that the precipitation proceeds through a face-to-face stacking of the nanoplatelets due to long-ranged van der Waals attraction. To address this issue, we coated the platelets with a carboxylic acid-terminated polystyrene, thus achieving colloidal stability while retaining the optical properties of the platelets.

Published
2015
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38. Spinal hyperostosis and ankylosis in a Gallo-Roman horse from Iwuy 'Val-de-Calvigny' (Nord, France): 'Ankylosing spondylarthritis' (spondylarthritis ankylopoetica), 'deforming spondylarthrosis' (spondylarthrosis deformans) or 'DISH' (hyperostosis vertebralis ankylopoetica)? An archeozoological and comparative nosological review.

Author

Lignereux Y and Bouet C

Abstract

A Gallo-roman horse from the ancient site of Iwuy ("Val-de-Calvigny", Nord, France) showed extensive lesions of severe vertebral ankylosing hyperostosis reliable to "ankylosing spondylarthritis/-osis" and "deforming spondylarthrosis". Discussing the case gives the opportunity to a comparative and critical review of spinal hyperostosing and ankylosing diseases in horse and man., (Copyright © 2015 Elsevier Inc. All rights reserved.)

Published
2015
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39. Real-time in situ probing of high-temperature quantum dots solution synthesis.

Author

Abécassis B, Bouet C, Garnero C, Constantin D, Lequeux N, Ithurria S, Dubertret B, Pauw BR, and Pontoni D

Subjects
Computer Systems, Hot Temperature, Scattering, Small Angle, Solutions chemistry, Crystallization methods, Materials Testing methods, Molecular Probe Techniques, Quantum Dots, X-Ray Diffraction methods
Abstract

Understanding the formation mechanism of colloidal nanocrystals is of paramount importance in order to design new nanostructures and synthesize them in a predictive fashion. However, reliable data on the pathways leading from molecular precursors to nanocrystals are not available yet. We used synchrotron-based time-resolved in situ small and wide-angle X-ray scattering to experimentally monitor the formation of CdSe quantum dots synthesized in solution through the heating up of precursors in octadecene at 240 °C. Our experiment yields a complete movie of the structure of the solution from the self-assembly of the precursors to the formation of the quantum dots. We show that the initial cadmium precursor lamellar structure melts into small micelles at 100 °C and that the first CdSe nuclei appear at 218.7 °C. The size distributions and concentration in nanocrystals are measured in a quantitative fashion as a function of time. We show that a short nucleation burst lasting 30 s is followed by a slow decrease of nanoparticle concentration. The rate-limiting process of the quantum dot formation is found to be the thermal activation of selenium.

Published
2015
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40. Phonon line emission revealed by self-assembly of colloidal nanoplatelets.

Author

Tessier MD, Biadala L, Bouet C, Ithurria S, Abecassis B, and Dubertret B

Subjects
Light, Materials Testing, Particle Size, Photons, Scattering, Radiation, Colloids chemistry, Luminescent Measurements, Nanostructures chemistry, Nanostructures ultrastructure
Abstract

We show that colloidal nanoplatelets can self-assemble to form a 1D superlattice. When self-assembled, an additional emission line appears in the photoluminescence spectrum at low temperatures. This emission line is a collective effect, greatly enhanced when the NPLs are self-assembled. It is attributed to the longitudinal optical (LO) phonon replica of the band-edge exciton, and its presence in self-assembled nanoplatelets is explained using a model based on an efficient photons reabsorption between neighboring nanoplatelets. The presence of phonon replica at low temperatures in ensemble measurements suggests the possibility to design a laser, based on self-assembled nanoplatelets.

Published
2013
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41. Core/shell colloidal semiconductor nanoplatelets.

Author

Mahler B, Nadal B, Bouet C, Patriarche G, and Dubertret B

Subjects
Cadmium Compounds chemical synthesis, Colloids chemical synthesis, Colloids chemistry, Particle Size, Selenium Compounds chemical synthesis, Semiconductors, Sulfides chemical synthesis, Surface Properties, Cadmium Compounds chemistry, Nanostructures chemistry, Selenium Compounds chemistry, Sulfides chemistry
Abstract

We have recently synthesized atomically flat semiconductor colloidal nanoplatelets with quasi 2D geometry. Here, we show that core/shell nanoplatelets can be obtained with a 2D geometry that is conserved. The epitaxial growth of the shell semiconductor is performed at room temperature. We report the detailed synthesis of CdSe/CdS and CdSe/CdZnS structures with different shell thicknesses. The shell growth is characterized both spectroscopically and structurally. In particular, the core/shell structure appears very clearly on high-resolution, high-angle annular dark-field transmission electron microscope images, thanks to the difference of atomic density between the core and the shell. When the nanoplatelets stand on their edge, we can precisely count the number of atomic planes forming the core and the shell. This provides a direct measurement, with atomic precision, of the core nanoplatelets thickness. The constraints exerted by the shell growth on the core is analyzed using global phase analysis. The core/shell nanoplatelets we obtained have narrow emission spectra with full-width at half-maximum close to 20 nm, and quantum yield that can reach 60%.

Published
2012
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42. Dust as a tipping element: the Bodele Depression, Chad.

Author

Washington R, Bouet C, Cautenet G, Mackenzie E, Ashpole I, Engelstaedter S, Lizcano G, Henderson GM, Schepanski K, and Tegen I

Abstract

Dust plays a vital role in climate and biophysical feedbacks in the Earth system. One source of dust, the Bodélé Depression in Chad, is estimated to produce about half the mineral aerosols emitted from the Sahara, which is the world's largest source. By using a variety of new remote sensing data, regional modeling, trajectory models, chemical analyses of dust, and future climate simulations, we investigate the current and past sensitivity of the Bodélé. We show that minor adjustments to small features of the atmospheric circulation, such as the Bodélé Low-Level Jet, could profoundly alter the behavior of this feature. Dust production during the mid-Holocene ceased completely from this key source region. Although subject to a great deal of uncertainty, some simulations of the 21st century indicate the potential for a substantial increase in dust production by the end of the century in comparison with current values.

Published
2009
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44. Glutamine synthetase genes are regulated by ammonia provided externally or by symbiotic nitrogen fixation.

Author

Hirel B, Bouet C, King B, Layzell D, Jacobs F, and Verma DP

Abstract

Glutamine synthetase is the key enzyme in the assimilation by plants of reduced nitrogen provided from either the soil or fixed symbiotically in association with Rhizobium. We have isolated a number of cDNA clones for soybean glutamine synthetase (GS) from a nodule-cDNA library, using RNA from polysomes immunoprecipitated by GS antibodies. Transcripts corresponding to two clones differing in their 3' non-translated sequences were present in both root and nodule tissue; however, the concentration in the nodules was several times higher. The relative concentrations of these sequences in both tissues is about 9:1. Availability of ammonium ions [provided as NH(4)NO(3) or (NH(4))(2)SO(4)] enhanced the expression of both sequences in root tissue within 2 h, reaching a level similar to that in nodules by 8 h, while KNO(3) had no effect during this period. When nitrogen fixation was prevented by replacing nitrogen with argon in the root environment or when the nodules were formed by a Fix mutant of Bradyrhizobium japonicum, the amounts of GS mRNA did not increase over that in roots. These experiments, together with the time course of increase in GS mRNA transcripts, suggest that the genes encoding cytosolic GS are directly induced by the available ammonia.

Published
1987
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