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CO2-rich phonolitic melt and carbonatite immiscibility in early stage of rifting: Melt inclusions from Hanang volcano (Tanzania)
Auteur(s): Baudouin Celine, Parat Fleurice, Michel T.
(Article) Publié:
Journal Of Volcanology And Geothermal Research, vol. 358 p.261-272 (2018)
Ref HAL: hal-02073090_v1
DOI: 10.1016/j.jvolgeores.2018.05.019
WoS: 000439678100020
Exporter : BibTex | endNote
2 Citations
Résumé: Hanang volcano is the southern volcano of, the southern area of the east part of the East African Rift (the North Tanzanian Divergence) and represents volcanic activity of the first stage of continental break-up. In this study, we investigate glassy melt inclusions in nepheline phenocrysts to constrain the late stage of Mg-poor nephelinite evolution and the behaviour of volatiles (CO2, H2O, S, F, Cl) during magma storage and ascent during early stage rifting. The melt inclusions have a green silicate glass, a carbonate phase and a shrinkage bubble free of gas phase indicating that carbonatite:silicate (18:82) liquid immiscibility occurred during nephelinite magmatic evolution. The silicate glasses have trachytic composition (Na + K/Al = 1.6–7.2, SiO2 = 54–65.5 wt%) with high CO2 (0.43 wt% CO2), sulfur (0.21–0.92 wt% S) and halogens (0.28–0.84 wt% Cl; 0.35–2.54 wt% F) contents and very low H2O content (<0.1 wt%). The carbonate phase is an anhydrous Ca-Na-K-S carbonate with 33 wt% CaO, 20 wt% Na2O, 3 wt% K2O, and 3 wt% S. The entrapped melt in nepheline corresponds to evolved interstitial CO2-rich phonolitic composition (Na + K/Al = 6.2–6.9) with 6 ± 1.5 wt% CO2 at pressure of 800 ± 200 MPa after crystallization of cpx (17%), nepheline (40%) garnet (6.5%) and apatite (1.7%) from Mg-rich nephelinitic magma. During ascent, immiscibility in phonolitic melt inclusions leads to Ca-Na carbonate melt with composition within the range of carbonate melt from Oldoinyo Lengai and Kerimasi, in equilibrium with trachytic silicate melt (closed-system, P < 500 MPa). The CO2-rich phonolitic melt inclusions from Hanang volcano may represent an early stage of differentiation before Na‑carbonatitic magmatism observed at Oldoinyo Lengai.
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Polarized Raman, FTIR, and DFT study of Na 2 Ti 3 O 7 microcrystals
Auteur(s): Silva Fábio Lacerda Resende e, Filho Adailton Azevedo Araújo, Silva Mauricélio Bezerra, Balzuweit Karla, Bantignies J.-L., Caetano Ewerton Wagner Santos, Moreira Roberto Luiz, Freire Valder Nogueira, Righi Ariete
(Article) Publié:
Journal Of Raman Spectroscopy, vol. 49 p.538-548 (2018)
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Isosteric heat of water adsorption and desorption in homoionic alkaline-earth montmorillonites
Auteur(s): Belhocine M., Haouzi A., Bassou G., Phou T., Maurin D., Bantignies J.-L., Henn F.
(Article) Publié:
Chemical Physics, vol. 501 p.26-34 (2018)
Ref HAL: hal-01927357_v1
DOI: 10.1016/j.chemphys.2017.11.012
WoS: WOS:000426452900004
Exporter : BibTex | endNote
3 Citations
Résumé: The aim of the present work is to study by means of thermodynamic measurements, i.e. isotherms of adsorption and desorption of water and Infrared (IR) spectroscopy, the effect of the interlayer cations on the mechanism of adsorption-desorption of water in the case of a montmorillonite exchanged with alkaline-earth metals. For the first time, the net isosteric heat of water adsorption and desorption is determined from isotherms recorded at three temperatures. The net isosteric heat is a very useful parameter for getting more insights into the sorption mechanism since it provides information about the sorption energy evolution which can be complementary to that obtained from structural or gravimetric measurements. The homoionic montmorillonite samples are prepared from purification and cationic exchanged in aqueous solution of the raw material, i.e the reference SWy-2 Wyoming material. XRD at the dry state and elemental chemical analysis confirm that the treatment does not deteriorate the clay structure and yield the expected homoionic composition. The adsorption and desorption isotherms measured at various temperatures show that the nature of the interlayer, i.e. exchangeable, cation changes the adsorbed/desorbed amount of water molecules for a given water relative pressure. The total amount of water adsorbed at = 0.5 follows the cation sequence Ca>Mg>Ba. Although the adsorption isosteric heat also follows the cation sequence Ca>Mg>Ba, that of desorption obeys a slightly different sequence Ca~Mg>Ba. This discrepancy between the adsorption and desorption heat is due to the higher irreversibility of water sorption process in the Ca exchanged montmorillonite. Finally, analysis of the IR spectra recorded at room temperature and under a primary vacuum reveals that the amount of adsorbed water follows the same sequence as that of the isosteric heat of adsorption and shows the coexistence of liquid-like and solid-like water confined in the interlayer space.
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Non-destructive DRIFT spectroscopy measurement of the degree of curing of industrial epoxy/silica composite buildup layers
Auteur(s): Granado Lérys, Maurin D., Kempa Stefan, Gregoriades Laurence, Brüning Frank, Fréty Nicole, Anglaret E., Bantignies J.-L.
(Article) Publié:
Polymer Testing, vol. 70 p.188 - 191 (2018)
Ref HAL: hal-01902659_v1
DOI: 10.1016/j.polymertesting.2018.07.007
WoS: 000445993600024
Exporter : BibTex | endNote
3 Citations
Résumé: The degree of curing of epoxy composites and coatings is one key parameter to control the reliability of manufacturing processes, particularly in printed circuit board (PCB) manufacturing where epoxy buildup composites are partially cured before processing. We show that the reaction of curing of an industrially relevant buildup composite (epoxy-phenol reinforced with silica fillers) can be monitored by diffuse reflectance infrared Fourier transform (DRIFT) in the near-infrared range. The accuracy of DRIFT measurements is confirmed by comparison with measurements in transmission mode on reference composite samples. DRIFT is demonstrated to offer an easy and reliable measurement of the epoxy degree of curing on PCB coupons.
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Carbon nanotubes functionalized with copper Hexacyanoferrate nanoparticles for a selective extraction of cesium from liquid waste
Auteur(s): Draouil H, Alvarez L., Causse Jérémy, Flaud V., Zaïbi M, Bantignies J.-L., Oueslati M, Cambedouzou J.
(Article) Publié:
Materials And Devices, vol. 3 #2 p.0407 (2018) (2018)
Texte intégral en Openaccess :
Ref HAL: hal-01845473_v1
DOI: 10.23647/ca.md20180407
Exporter : BibTex | endNote
Résumé: Single-walled carbon nanotubes are functionalized with copper hexacyanoferrate nanoparticles for the liquid-solid extraction of cesium from liquid waste and contaminated water. The functionalization process is followed mainly by x-ray photoemission spectroscopy. Indeed, determining the chemical environment around carbon or nitrogen atoms allows to evidence the formation of covalent bounding. In addition, the signatures of iron and copper ions give information on the effective growth of hexacyanoferrate nanoparticles. Furthermore, the cesium sorption mechanism is investigated by comparing the peak intensities associated to the response of potassium and cesium ions. Finally, based on the liquid chromatography analyzes, the sorption of cesium with the functionalized carbon supports is studied. The main results of this work are the demonstration of both a good selectivity of cesium trapping and a high sorption capacity by hybrid single-walled carbon nanotubes.
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Intralayer and interlayer electron-phonon interactions in twisted graphene heterostructures
Auteur(s): Eliel G. S. N., Moutinho M. V. O., Gadelha A. C., Righi A., Campos L. C., Ribeiro H. B., Chiu Po-Wen, Watanabe K., Taniguchi T., Puech Pascal, Paillet M., Michel T., Venezuela P., Pimenta M. A.
(Article) Publié:
Nature Communications, vol. 9 p.1221 (2018)
Texte intégral en Openaccess :
Ref HAL: hal-01793669_v1
DOI: 10.1038/s41467-018-03479-3
WoS: WOS:000428165400020
Exporter : BibTex | endNote
29 Citations
Résumé: The understanding of interactions between electrons and phonons in atomically thin heterostructures is crucial for the engineering of novel two-dimensional devices. Electron–phonon (el–ph) interactions in layered materials can occur involving electrons in the same layer or in different layers. Here we report on the possibility of distinguishing intralayer and interlayer el–ph interactions in samples of twisted bilayer graphene and of probing the intralayer process in graphene/h-BN by using Raman spectroscopy. In the intralayer process, the el–ph scattering occurs in a single graphene layer and the other layer (graphene or h-BN) imposes a periodic potential that backscatters the excited electron, whereas for the interlayer process the el–ph scattering occurs between states in the Dirac cones of adjacent graphene layers. Our methodology of using Raman spectroscopy to probe different types of el–ph interactions can be extended to study any kind of graphene-based heterostructure.
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C 9/12 Ribbon-Like Structures in Hybrid Peptides Alternating α- and Thiazole-Based γ-Amino Acids
Auteur(s): Bonnel Clément, Legrand Baptiste, Simon Matthieu, Martinez Jean, Bantignies J.-L., Kang Young Kee, Wenger Emmanuel, Hoh Francois, Masurier Nicolas, Maillard Ludovic
(Article) Publié:
Chemistry - A European Journal, vol. 23 p.17584-17591 (2017)
Ref HAL: hal-02359324_v1
DOI: 10.1002/chem.201704001
WoS: 000417652800025
Exporter : BibTex | endNote
4 Citations
Résumé: According to their restricted conformational freedom, heterocyclic -amino acids are usually considered to be related to Z-vinylogous -amino acids. In this context, oligomers alternating -amino acids and thiazole-based -amino acids (ATCs) were expected to fold into a canonical 12-helical shape as described for /-hybrid peptides composed of cis-/-unsaturated -amino acids. However, through a combination of X-ray crystallography, NMR spectroscopy, FTIR experiments, and DFT calculations, it was determined that the folding behavior of ATC-containing hybrid peptides is much more complex. The homochiral /(S)-ATC sequences were unable to adopt a stable conformation, whereas the heterochiral /(R)-ATC peptides displayed novel ribbon structures stabilized by unusual C-9/12-bifurcated hydrogen bonds. These ribbon structures could be considered as a succession of pre-organized / dipeptides and may provide the basis for designing original -helix mimics.
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