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7. Ultrastructural Perspectives on the Biology and Taphonomy of Tonian Microfossils From the Draken Formation, Spitsbergen.

Author

Fadel, Alexandre, Lepot, Kevin, Bernard, Sylvain, Addad, Ahmed, Riboulleau, Armelle, and Knoll, Andrew H.

Subjects
*CELL envelope (Biology), *FOCUSED ion beams, *INTRACELLULAR space, *X-ray absorption near edge structure, *TRANSMISSION electron microscopy, *APICOMPLEXA
Abstract

Silicified peritidal carbonates of the Tonian Draken Formation, Spitsbergen, contain highly diverse and well‐preserved microfossil assemblages dominated by filamentous microbial mats, but also including diverse benthic and/or allochthonous (possibly planktonic) microorganisms. Here, we characterize eight morphospecies in focused ion beam (FIB) ultrathin sections using transmission electron microscopy (TEM) and X‐ray absorption near‐edge structure (XANES) spectromicroscopy. Raman and XANES spectroscopies show the highly aromatic molecular structure of preserved organic matter. Despite this apparently poor molecular preservation, nano‐quartz crystallization allowed for the preservation of various ultrastructures distinguished in TEM. In some filamentous microfossils (Siphonophycus) as well as in all cyanobacterial coccoids, extracellular polysaccharide sheaths appear as bands of dispersed organic nanoparticles. Synodophycus microfossils, made up of pluricellular colonies of coccoids, contain organic walls similar to the F‐layers of pleurocapsalean cyanobacteria. In some fossils, internal content occurs as particulate organic matter, forming dense networks throughout ghosts of the intracellular space (e.g., in Salome svalbardensis filaments), or scarce granules (in some Chroococcales). In some chroococcalean microfossils (Gloeodiniopsis mikros, and also possibly Polybessurus), we find layered internal contents that are more continuous than nanoparticulate bands defining the sheaths, and with a shape that can be contracted, folded, or invaginated. We interpret these internal layers as the remains of cell envelope substructures and/or photosynthetic membranes thickened by additional cellular material. Some Myxococccoides show a thick (up to ~ 0.9 μm) wall ultrastructure displaying organic pillars that is best reconciled with a eukaryotic affinity. Finally, a large spheroid with ruptured wall, of uncertain affinity, displays a bi‐layered envelope. Altogether, our nanoscale investigations provide unprecedented insights into the taphonomy and taxonomy of this well‐preserved assemblage, which can help to assess the nature of organic microstructures in older rocks. [ABSTRACT FROM AUTHOR]

Published
2024
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11. Unlocking the Potential of MXene in Catalysis: Decorated Mo2CTxCatalyst for Ammonia Synthesis under Mild Conditions

Author

Sfeir, Amanda, Shuck, Christopher E., Fadel, Alexandre, Marinova, Maya, Vezin, Hervé, Dacquin, Jean-Philippe, Gogotsi, Yury, Royer, Sébastien, and Laassiri, Said

Abstract

Ammonia, which is one of the most important chemicals for the synthesis of dyes, pharmaceuticals, and fertilizers, is produced by the reaction of molecular hydrogen with nitrogen, over an iron-based catalyst at 400–500 °C under pressure of over 100 bar. Decreasing the operating temperature and pressure of this highly energy-intensive process, developed by Haber and Bosch over 100 years ago, would decrease energy consumption in the world. In this work, we used two-dimensional Mo2CTxMXene as a support for a cobalt-based catalyst. The MXene functionalized by Co showed catalytic activity for ammonia synthesis from H2and N2at temperatures as low as 250 °C, without any pretreatment. The developed catalyst was highly active for ammonia synthesis, demonstrating a high rate of up to 9500 μmol g–1active phaseh–1at 400 °C under ambient pressure in steady-state conditions, and did not suffer from any deactivation after 15 days of reaction. The apparent activation energy (Ea) was found to be in the range of 68–74 kJ mol–1, which is in line with values reported for highly active catalysts. This improved catalyst may decrease the energy consumption in the synthesis of ammonia and its derivatives, as well as facilitate the use of ammonia as a hydrogen carrier for renewable energy storage.

Published
2024
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14. Formation of Three‐Dimensional Polysuccinimide Electrospun Fiber Meshes Induced by the Combination of CaCl2 and Humidity.

Author

Juhász, Ákos György, Nanys, Monika, Pinke, Balázs, Fadel, Alexandre, Godzierz, Marcin, Juriga‐Tóth, Krisztina, Molnár, Kolos, Juriga, Dávid, and Jedlovszky‐Hajdú, Angéla

Subjects
HUMIDITY, FIBERS, SCANNING electron microscopy, X-ray diffraction, TISSUE engineering
Abstract

Even though electrospinning is getting more and more attention, the preparation of 3D nanofibrous meshes is still a big challenge that limits the application of electrospun materials, especially in tissue engineering. To overcome this problem, several solutions are introduced but most of them focus on the postprocessing of the electrospun meshes. This paper presents a straightforward novel method that utilizes the joint effect of the addition of CaCl2 and the relative environmental humidity (RH), which can induce the random 3D formation of polysuccinimide (PSI) electrospun fibers with different such as wrinkled or ribbon‐like structures. Although the effect of humidity and inorganic salt additives on the micro and macrostructure of electrospun fibers is known, the connection between the two in this manner has never been presented. To investigate the effect, fibers with different PSI and CaCl2 concentrations at different humidity RH levels are prepared, and their microstructure is visualized with high‐resolution scanning electron microscopy (SEM). To reveal the nature of the interaction between the polymer and the CaCl2, Fourier‐transformed infrared (FTIR), X‐ray diffraction (XRD), and thermogravimetry (TGA) measurements are carried out and 3D nanofibrous structures are obtained. [ABSTRACT FROM AUTHOR]

Published
2024
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15. Hurdle technology based on the use of microencapsulated pepsin, trypsin and carvacrol to eradicate Pseudomonas aeruginosa and Enterococcus faecalis biofilms

Author

Mechmechani, Samah, Gharsallaoui, Adem, Omari, Khaled El, Fadel, Alexandre, Hamze, Monzer, and Chihib, Nour-Eddine

Subjects
Aquatic Science, Applied Microbiology and Biotechnology, Water Science and Technology
Abstract

The biofilm lifestyle plays a major role in the resistance and virulence of Pseudomonas aeruginosa and Enterococcus faecalis. In this study, two microencapsulated proteases (pepsin ME-PEP and trypsin ME-TRYP) were evaluated for their biofilm dispersal activity and their synergistic effect with microencapsulated carvacrol (ME-CARV). Spray-drying was used to protect enzymes and essential oil and enhance their activities. Cell count analysis proved the synergistic activity of enzymes and carvacrol treatment as biofilms were further reduced after combined treatment in comparison to ME-CARV or enzymes alone. Furthermore, results showed that sequential treatment in the order ME-TRYP - ME-PEP - ME-CARV resulted in more efficient biofilm removal with a maximum reduction of 5 log CFU mL−1 for P. aeruginosa and 4 log CFU mL−1 for E. faecalis. This study proposes that the combination of microencapsulated proteases with ME-CARV could be useful for the effective control of P. aeruginosa and E. faecalis biofilms.

Published
2022
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21. Paleoenvironments revealed by rare-earth element systematics in vertebrate bioapatite from the Lower Devonian of Svalbard (1)

Author

Zigaite, Zivile, Fadel, Alexandre, Perez-Huerta, Alberto, Jeffries, Teresa, Goujet, Daniel, and Ahlberg, Per Erik

Subjects
Apatite -- Natural history, Earth sciences
Abstract

Abstract: In situ rare-earth element (REE) compositions have been measured in early vertebrate microremains from the Lower Devonian basin of Andree Land (Svalbard), with the aim of obtaining information about [...]

Published
2016

22. Etude de copolymères piézoélectriques fluorés

Author

Girardot, Melanie, Addad, Ahmed, Tahon, Jean-Francois, Fadel, Alexandre, Lyskawa, Joel, Barrau, Sophie, Unité Matériaux et Transformations - UMR 8207 (UMET), Centrale Lille-Institut de Chimie du CNRS (INC)-Université de Lille-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE), and Section Est du Groupe Français des Polymères

Subjects
[CHIM.POLY]Chemical Sciences/Polymers, [CHIM.MATE]Chemical Sciences/Material chemistry
Abstract

International audience

Published
2022

23. Etudes comparatives de différents copolymères piézoélectriques fluorés

Author

Girardot, Melanie, Addad, Ahmed, Marin, Adeline, Tahon, Jean-Francois, Fadel, Alexandre, Lyskawa, Joel, Barrau, Sophie, Unité Matériaux et Transformations - UMR 8207 (UMET), Institut National de la Recherche Agronomique (INRA)-Ecole Nationale Supérieure de Chimie de Lille (ENSCL)-Institut de Chimie du CNRS (INC)-Université de Lille-Centre National de la Recherche Scientifique (CNRS), Laboratoire d’Océanologie et de Géosciences (LOG) - UMR 8187 (LOG), and Institut national des sciences de l'Univers (INSU - CNRS)-Université du Littoral Côte d'Opale (ULCO)-Université de Lille-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD [France-Nord])

Subjects
[CHIM.POLY]Chemical Sciences/Polymers, [CHIM.MATE]Chemical Sciences/Material chemistry
Abstract

National audience

Published
2022

24. Utilization of Catechol End-Functionalized PMMA as a Macromolecular Coupling Agent for Ceramic/Fluoropolymer Piezoelectric Composites

Author

Bouad, Vincent, primary, Fadel, Alexandre, additional, Mohan, Saj, additional, Hamieh, Arthur, additional, Tahon, Jean-François, additional, Lyskawa, Joël, additional, Woisel, Patrice, additional, Da Costa, Antonio, additional, Ferri, Anthony, additional, Desfeux, Rachel, additional, Ponchel, Freddy, additional, Remiens, Denis, additional, Ladmiral, Vincent, additional, and Barrau, Sophie, additional

Published
2022
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25. Étude de l'adhésion interfaciale dans les composites piézoélectriques à matrice fluoropolymère

Author

Bouad, Vincent, Mohan, M.M. Saj, Fadel, Alexandre, Hamied, Ahmad, Marin, Adeline, Tahon, Jean-François, Addad, Ahmed, Ferri, Anthony, Costa, Antonio Da, Desfeux, Rachel, Ponchel, Freddy, Remiens, Denis, Lyskawa, Joël, Lefebvre, Jean-Marc, Barrau, Sophie, Ladmiral, Vincent, Unité Matériaux et Transformations - UMR 8207 (UMET), Centrale Lille-Institut de Chimie du CNRS (INC)-Université de Lille-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE), MESA+ Research Institute, University of Twente, Institut d’Électronique, de Microélectronique et de Nanotechnologie - UMR 8520 (IEMN), Centrale Lille-Université de Lille-Centre National de la Recherche Scientifique (CNRS)-Université Polytechnique Hauts-de-France (UPHF)-JUNIA (JUNIA), Université catholique de Lille (UCL)-Université catholique de Lille (UCL), UCCS Équipe Couches Minces & Nanomatériaux, Unité de Catalyse et Chimie du Solide - UMR 8181 (UCCS), Université d'Artois (UA)-Centrale Lille-Institut de Chimie du CNRS (INC)-Université de Lille-Centre National de la Recherche Scientifique (CNRS)-Université d'Artois (UA)-Centrale Lille-Institut de Chimie du CNRS (INC)-Université de Lille-Centre National de la Recherche Scientifique (CNRS), Université d'Artois (UA)-Centrale Lille-Institut de Chimie du CNRS (INC)-Université de Lille-Centre National de la Recherche Scientifique (CNRS), Matériaux et Acoustiques pour MIcro et NAno systèmes intégrés - IEMN (MAMINA - IEMN), INSA Institut National des Sciences Appliquées Hauts-de-France (INSA Hauts-De-France), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Institut d’Électronique, de Microélectronique et de Nanotechnologie - UMR 8520 (IEMN), Université catholique de Lille (UCL)-Université catholique de Lille (UCL)-Centrale Lille-Université de Lille-Centre National de la Recherche Scientifique (CNRS)-Université Polytechnique Hauts-de-France (UPHF)-JUNIA (JUNIA), Institut Charles Gerhardt Montpellier - Institut de Chimie Moléculaire et des Matériaux de Montpellier (ICGM), Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Université de Montpellier (UM)-Ecole Nationale Supérieure de Chimie de Montpellier (ENSCM), and Université de Montpellier (UM)

Subjects
[CHIM.MATE]Chemical Sciences/Material chemistry
Abstract

National audience

Published
2022

26. Relations entre la structure et les propriétés de composites piézoélectriques de BTO/P(VDF-co-TrFE)

Author

Girardot, Melanie, Addad, Ahmed, Tahon, Jean-Francois, Fadel, Alexandre, Marin, Adeline, Bouad, Vincent, Lyskawa, Joel, Barrau, Sophie, Unité Matériaux et Transformations - UMR 8207 (UMET), Centrale Lille-Institut de Chimie du CNRS (INC)-Université de Lille-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE), Institut Michel Eugène Chevreul - FR 2638 (IMEC), and Université d'Artois (UA)-Centrale Lille-Institut de Chimie du CNRS (INC)-Université de Lille-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)

Subjects
[CHIM.MATE]Chemical Sciences/Material chemistry
Abstract

National audience

Published
2022

30. eformation Mechanisms In Fine-grained MgO Periclase At Pressures Of 1.6-8.3 GPa And Temperatures Of 875-1270 K

Author

Ledoux, Estelle, Lin, Feng, Miyagi, Lowell M, Addad, Ahmed, Fadel, Alexandre, Béclin, Franck, Merkel, Sébastien, Unité Matériaux et Transformations - UMR 8207 (UMET), Centrale Lille-Institut de Chimie du CNRS (INC)-Université de Lille-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE), and ANR-17-CE31-0025,TIMEleSS,Transformations de phase, microstructures, et leur signatures sismiques dans le manteau terrestre(2017)

Subjects
[SDU.ASTR]Sciences of the Universe [physics]/Astrophysics [astro-ph], [PHYS.COND.CM-MS]Physics [physics]/Condensed Matter [cond-mat]/Materials Science [cond-mat.mtrl-sci], [SDU.STU]Sciences of the Universe [physics]/Earth Sciences, [PHYS.PHYS.PHYS-GEO-PH]Physics [physics]/Physics [physics]/Geophysics [physics.geo-ph], [CHIM.MATE]Chemical Sciences/Material chemistry, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], ComputingMilieux_MISCELLANEOUS
Abstract

International audience

Published
2021

31. Intracellular detection of nickel-porphyrins moieties in a 1-Gyr old multicellular alga allows to track early phototrophy

Author

Sforna, Marie Catherine, Loron, Corentin C., Demoulin, Catherine F., Francois, Camille, Cornet, Yohan, Lara, Yannick J., Grolimund, Daniel, Ferreira Sanchez, Dario, Medjoubi, Kadda, Somogyi, Andrea, Addad, Ahmed, Fadel, Alexandre, Compère, Philippe, Baudet, Daniel, Brocks, Jochen, Javaux, Emmanuelle, Synchrotron SOLEIL (SSOLEIL), Centre National de la Recherche Scientifique (CNRS), Unité Matériaux et Transformations - UMR 8207 (UMET), Centrale Lille-Institut de Chimie du CNRS (INC)-Université de Lille-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE), and SGF, CNRS, Laboratoire de Géologie de Lyon ou l’étude de la Terre, des planètes et de l’environnement

Subjects
Tetrapyrrole moieties, Photosynthetic eukaryotes, Organic, walled microfossils, [SDU]Sciences of the Universe [physics], Precambrian, Ecosystem evolution, ComputingMilieux_MISCELLANEOUS
Abstract

International audience

Published
2021

32. In-situ studies of olivine-wadsleyite transformation and related microstructures between 12 to 22 GPa and 1500 to 1700 K

Author

Ledoux, Estelle, Chantel, Julien, Hilairet, Nadege, Svitlyk, Volodymyr, Byka, Maxime, Bykova, Elena, Aprilis, Georges, Fadel, Alexandre, Merkel, Sébastien, Unité Matériaux et Transformations - UMR 8207 (UMET), Institut de Chimie du CNRS (INC)-Université de Lille-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Centrale Lille Institut (CLIL), ANR-17-CE31-0025,TIMEleSS,Transformations de phase, microstructures, et leur signatures sismiques dans le manteau terrestre(2017), and Centrale Lille-Institut de Chimie du CNRS (INC)-Université de Lille-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)

Subjects
[PHYS.COND.CM-MS]Physics [physics]/Condensed Matter [cond-mat]/Materials Science [cond-mat.mtrl-sci], [SDU.STU]Sciences of the Universe [physics]/Earth Sciences, [PHYS.PHYS.PHYS-GEO-PH]Physics [physics]/Physics [physics]/Geophysics [physics.geo-ph]
Abstract

International audience; The 410 km depth seismic discontinuity in the Earth is attributed to the transformation from olivine to its high pressure polymorph, wadsleyite (Ringwood, 1969). This phase transformation can be martensitic-like, i.e. with a crystallographic orientation relationship between the parent crystal and the transformed crystal, but not in all cases (Smyth et al., 2012). In a martensitic-like phase transformation wadsleyite inherits a lattice preferred orientation (LPO) from the starting olivine. Hence, a LPO in olivine will be inherited by wadsleyite and could give rise to seismic anisotropy to the mantle transition zone. However, in the case of a non martensitic-like transformation, no trace of the upper mantle olivine LPO will be preserved by the newly-formed wadsleyite.In order to determine which scenario applies at the conditions of the 410 km depth discontinuity, we reproduce the transformation in the laboratory. We use polycrystalline samples of pure olivine loaded in diamond anvil cells inside a pressure medium and apply combined pressure and temperature to induce the phase transformation. The evolution of the sample’s microstructure is followed using in-situ X-rays diffraction at the beamlines ID27 of the ESRF and P02 at PETRA III (DESY). Key steps of the transformation are documented by 3D-XRD data collections. Data processing of these 3D-RXD collections with the multigrain crystallography method give us information about orientations and positions of individual grains in the samples all along the experiment. Based on the orientation of these grains, we track the texture evolution during the experiments and search for evidences of a crystallographic orientation relationships between the two phases. This characterization will allow us to determine the transformation mechanism occurring at the conditions of the 410 km discontinuity and the effect of the transformation on the seismic anisotropy in the Earth’s mantle.

Published
2021

33. Post-mortem electron microsopy study of plastic deformation in MgO periclase

Author

Ledoux, Estelle, Lin, Feng, Miyagi, Lowell M, Addad, Ahmed, Fadel, Alexandre, Merkel, Sébastien, Jacob, Damien, Unité Matériaux et Transformations - UMR 8207 (UMET), Institut de Chimie du CNRS (INC)-Université de Lille-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Centrale Lille Institut (CLIL), ANR-17-CE31-0025,TIMEleSS,Transformations de phase, microstructures, et leur signatures sismiques dans le manteau terrestre(2017), and Centrale Lille-Institut de Chimie du CNRS (INC)-Université de Lille-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)

Subjects
[SDU.ASTR]Sciences of the Universe [physics]/Astrophysics [astro-ph], [PHYS.COND.CM-MS]Physics [physics]/Condensed Matter [cond-mat]/Materials Science [cond-mat.mtrl-sci], [SDU.STU]Sciences of the Universe [physics]/Earth Sciences, [PHYS.PHYS.PHYS-GEO-PH]Physics [physics]/Physics [physics]/Geophysics [physics.geo-ph], [CHIM.MATE]Chemical Sciences/Material chemistry, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], ComputingMilieux_MISCELLANEOUS
Abstract

National audience

Published
2020

34. In situ detection of bound Ni-tetrapyrrole moieties in ~1 Gyr-old eukaryote microfossil suggesting its phototrophy

Author

Sforna, Marie Catherine, primary, Loron, Corentin, additional, Demoulin, Catherine, additional, François, Camille, additional, Cornet, Yohan, additional, Lara, Yannick, additional, Grolimund, Daniel, additional, Ferreira Sanchez, Dario, additional, Medjoubi, Kadda, additional, Somogyi, Andrea, additional, Addad, Ahmed, additional, Fadel, Alexandre, additional, Compère, Philippe, additional, Brocks, Jochen, additional, Javaux, Emmanuelle, additional, and Baudet, Daniel, additional

Published
2021
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36. Integrative paleontological and geochemical study of the microfossil Polysphaeroides filiformis and its implication for deep time cyanobacterial evolution

Author

Demoulin, Catherine, primary, Sforna, Marie Catherine, additional, Lara, Yannick, additional, Loron, Corentin, additional, Cornet, Yohan, additional, Tucoulou Tachoueres, Remi, additional, Grolimund, Daniel, additional, Ferreira Sanchez, Dario, additional, Addad, Ahmed, additional, Fadel, Alexandre, additional, Compère, Philippe, additional, and Javaux, Emmanuelle, additional

Published
2021
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38. Analyses par EBSD de la déformation dans le périclase MgO

Author

Ledoux, Estelle, Lin, Feng, Miyagi, Lowell M, Addad, Ahmed, Fadel, Alexandre, Merkel, Sébastien, Jacob, Damien, Unité Matériaux et Transformations - UMR 8207 (UMET), Centre National de la Recherche Scientifique (CNRS)-Université de Lille-Ecole Nationale Supérieure de Chimie de Lille (ENSCL)-Institut National de la Recherche Agronomique (INRA), University of Utah, ANR-17-CE31-0025,TIMEleSS,Transformations de phase, microstructures, et leur signatures sismiques dans le manteau terrestre(2017), Institut de Chimie du CNRS (INC)-Institut National de la Recherche Agronomique (INRA)-Centre National de la Recherche Scientifique (CNRS)-Université de Lille-Ecole Nationale Supérieure de Chimie de Lille (ENSCL), and Institut National de la Recherche Agronomique (INRA)-Ecole Nationale Supérieure de Chimie de Lille (ENSCL)-Institut de Chimie du CNRS (INC)-Université de Lille-Centre National de la Recherche Scientifique (CNRS)

Subjects
[SDU.ASTR]Sciences of the Universe [physics]/Astrophysics [astro-ph], [PHYS.COND.CM-MS]Physics [physics]/Condensed Matter [cond-mat]/Materials Science [cond-mat.mtrl-sci], [SDU.STU]Sciences of the Universe [physics]/Earth Sciences, [PHYS.PHYS.PHYS-GEO-PH]Physics [physics]/Physics [physics]/Geophysics [physics.geo-ph], [CHIM.MATE]Chemical Sciences/Material chemistry, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], ComputingMilieux_MISCELLANEOUS
Abstract

National audience

Published
2019

39. Nickel as Tracer of Oxygenic Phototrophy in the Fossil Record

Author

Sforna, Marie Catherine, primary, Loron, Corentin C., additional, Demoulin, Catherine F., additional, François, Camille, additional, Cornet, Yohan, additional, Lara, Yannick J., additional, Grolimund, Daniel, additional, Sanchez, Dario, additional, Medjoubi, Kadda, additional, Somogyi, Andrea, additional, Addad, Ahmed, additional, Fadel, Alexandre, additional, Compère, Philippe, additional, and Javaux, Emmanuelle J., additional

Published
2020
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40. Judicialização do federalismo e federalismo formal = Judicialization of federalism and formal federalism

Author

Rangel, Henrique, Fadel, Alexandre, Neri, Bianca, and Bolonha, Carlos

Abstract

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Published
2016

41. Palaeoenvironments revealed by rare-earth element systematics in vertebrate bioapatite from the Lower Devonian of Svalbard

Author

Zigaite, Zivile, Fadel, Alexandre, Perez-Huerta, Alberto, Jeffries, Teresa, Goujet, Daniel, Ahlberg, Per, Zigaite, Zivile, Fadel, Alexandre, Perez-Huerta, Alberto, Jeffries, Teresa, Goujet, Daniel, and Ahlberg, Per

Abstract

In situ rare-earth element (REE) compositions have been measured in early vertebrate microremains from the Lower Devonian basin of Andree Land (Svalbard), with the aim of obtaining information about their early depositional environment and potential reworking. Vertebrate microremains with different histology were used for the analyses, sourced from two different localities of marginal marine to freshwater sediments from geographically distant parts of the Grey Hoek Formation (Skamdalen and Tavlefjellet members). We selected thelodont and undescribed ? chondrichthyan scales, which allowed us to define potential taxonomic, histological, and taphonomic variables of the REE uptake. Results showed REE concentrations to be relatively uniform within the scales of each taxon, but apparent discrepancies were visible between the studied localities and separate taxa. The compilation of REE abundance patterns as well as REE ratios have revealed that thelodont and ? chondrichthyan originating from the same locality must have had different burial and early diagenetic histories. The shapes of the REE profiles, together with the presence and absence of the Eu and Ce anomalies, equally suggested different depositional and diagenetic environments for these two sympatric taxa resulting from either stratigraphical or long-distance reworking. The REE concentrations appear to have visible differences between separate dental tissues, particularly between enameloid and dentine of thelodonts, emphasizing the importance of in situ measurements in microfossil biomineral geochemistry.

Published
2016
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43. Palaeoenvironmental signatures revealed from rare earth element (REE) compositions of vertebrate microremains of the Vesiku Bone Bed (Homerian, Wenlock), Saaremaa Island, Estonia

Author

Fadel, Alexandre, Zigaite, Zivile, Blom, Henning, Perez-Huerta, Alberto, Jeffries, Teresa, Maersse, Tiiu, Ahlberg, Per Erik, Fadel, Alexandre, Zigaite, Zivile, Blom, Henning, Perez-Huerta, Alberto, Jeffries, Teresa, Maersse, Tiiu, and Ahlberg, Per Erik

Abstract

Rare earth elements (REEs) have been analysed from fossil vertebrate microremains (thelodont scales) from the Vesiku Bone Bed, Saaremaa, Estonia, using in situ microsampling by laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS). Well-preserved scales of three species of the genus Thelodus (T. carinatus, T. laevis and Thelodus sp.) show very uniform REE patterns with slightly lower overall REE concentrations in enameloid than in dentine, with enrichment in middle REEs, depletion in heavy REEs and pronounced negative europium anomaly, but no cerium anomaly. The results of this study suggest a similar diagenetic history and possibly contemporaneous habitats for all three Thelodus species, as well as possible suboxic to anoxic conditions of the bottom and pore waters during the formation of the Vesiku Bone Bed.

Published
2015
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44. Rare earth elements (REEs) in vertebrate microremains from the upper Pridoli Ohesaare beds of Saaremaa Island, Estonia : geochemical clues to palaeoenvironment

Author

Zigaite, Zivile, Fadel, Alexandre, Blom, Henning, Perez-Huerta, Alberto, Jeffries, Teresa, Maerss, Tiiu, Ahlberg, Per Erik, Zigaite, Zivile, Fadel, Alexandre, Blom, Henning, Perez-Huerta, Alberto, Jeffries, Teresa, Maerss, Tiiu, and Ahlberg, Per Erik

Abstract

Rare earth element (REE) compositions of Nostolepis sp. scales, spines, plates and tesserae from Ohesaare bone beds were measured by in situ microsampling using laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS). The obtained REE concentrations, normalized to Post-Archean Australian Shale concentrations, were evaluated using basic geochemical calculations and quantifications. The REE compositions were nearly identical across all the morphotypes and histologies of Nostolepis microremains, showing flat REE patterns with slight depletion in heavy REEs. There was no visible enrichment in middle REEs, indicating good geochemical preservation of bioapatite and absence of any pronounced fractionated REE incorporation during later stages of diagenesis. The shale-normalized (La/Yb)(SN) and (La/Sm)(SN) REE ratio compilations indicated adsorption as the dominating REE uptake mechanism across all datapoints. The absence of well-defmed Ce anomaly suggested oxic palaeoseawater conditions, which agrees with the existing interpretations of the Ohesaare sequence as high-energy shoal and regressive open ocean sedimentary environments.

Published
2015
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47. Paleoenvironments revealed by rare-earth element systematics in vertebrate bioapatite from the Lower Devonian of Svalbard1.

Author

Žigaitė, Živilė, Fadel, Alexandre, Pérez-Huerta, Alberto, Jeffries, Teresa, Goujet, Daniel, Ahlberg, Per Erik, and Jin, Jisuo

Subjects
*RARE earth metals, *PRACTICE of dentistry, *COELOLEPIDA, *BIOMINERALIZATION, *GEOCHEMISTRY
Abstract

In situ rare-earth element (REE) compositions have been measured in early vertebrate microremains from the Lower Devonian basin of Andrée Land (Svalbard), with the aim of obtaining information about their early depositional environment and potential reworking. Vertebrate microremains with different histology were used for the analyses, sourced from two different localities of marginal marine to freshwater sediments from geographically distant parts of the Grey Hœk Formation (Skamdalen and Tavlefjellet members). We selected thelodont and undescribed ?chondrichthyan scales, which allowed us to define potential taxonomic, histological, and taphonomic variables of the REE uptake. Results showed REE concentrations to be relatively uniform within the scales of each taxon, but apparent discrepancies were visible between the studied localities and separate taxa. The compilation of REE abundance patterns as well as REE ratios have revealed that thelodont and ?chondrichthyan originating from the same locality must have had different burial and early diagenetic histories. The shapes of the REE profiles, together with the presence and absence of the Eu and Ce anomalies, equally suggested different depositional and diagenetic environments for these two sympatric taxa resulting from either stratigraphical or long-distance reworking. The REE concentrations appear to have visible differences between separate dental tissues, particularly between enameloid and dentine of thelodonts, emphasizing the importance of in situ measurements in microfossil biomineral geochemistry. [ABSTRACT FROM AUTHOR]

Published
2016
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48. Paleoenvironments revealed by rare-earth element systematics in vertebrate bioapatite from the Lower Devonian of Svalbard1.

Author

Žigaitė, Živilė, Fadel, Alexandre, Pérez-Huerta, Alberto, Jeffries, Teresa, Goujet, Daniel, Ahlberg, Per Erik, and Jin, Jisuo

Subjects
RARE earth metals, PRACTICE of dentistry, COELOLEPIDA, BIOMINERALIZATION, GEOCHEMISTRY
Abstract

Copyright of Canadian Journal of Earth Sciences is the property of Canadian Science Publishing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Published
2016
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50. Unlocking the Potential of MXene in Catalysis: Decorated Mo 2 CT x Catalyst for Ammonia Synthesis under Mild Conditions.

Author

Sfeir A, Shuck CE, Fadel A, Marinova M, Vezin H, Dacquin JP, Gogotsi Y, Royer S, and Laassiri S

Abstract

Ammonia, which is one of the most important chemicals for the synthesis of dyes, pharmaceuticals, and fertilizers, is produced by the reaction of molecular hydrogen with nitrogen, over an iron-based catalyst at 400-500 °C under pressure of over 100 bar. Decreasing the operating temperature and pressure of this highly energy-intensive process, developed by Haber and Bosch over 100 years ago, would decrease energy consumption in the world. In this work, we used two-dimensional Mo 2 CT x MXene as a support for a cobalt-based catalyst. The MXene functionalized by Co showed catalytic activity for ammonia synthesis from H 2 and N 2 at temperatures as low as 250 °C, without any pretreatment. The developed catalyst was highly active for ammonia synthesis, demonstrating a high rate of up to 9500 μmol g -1 active phase h -1 at 400 °C under ambient pressure in steady-state conditions, and did not suffer from any deactivation after 15 days of reaction. The apparent activation energy ( E a ) was found to be in the range of 68-74 kJ mol -1 , which is in line with values reported for highly active catalysts. This improved catalyst may decrease the energy consumption in the synthesis of ammonia and its derivatives, as well as facilitate the use of ammonia as a hydrogen carrier for renewable energy storage.

Published
2024
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