Search results for "Titan"
showing 10 items of 1109 documents
Towards a converged barrier height for the entrance channel transition state of the N(2D)+CH4 reaction and its implication for the chemistry in Titan…
2011
Abstract The N( 2 D) + CH 4 reaction appears to be a key reaction for the chemistry of Titan’s atmosphere, opening the door to nitrile formation as recently observed by the Cassini–Huygens mission. Faced to the controversy concerning the existence or not of a potential barrier for this reaction, we have carried out accurate ab initio calculations by means of multi-state multi-reference configuration interaction (MS-MR-SDCI) method. These calculations have been partially corrected for the size-consistency errors (SCE) by Davidson, Pople or AQCC corrections. We suggest a barrier height of 3.86 ± 0.84 kJ/mol, including ZPE, for the entrance transition state, in good agreement with the experime…
Titanium dioxide in dental enamel as a trace element and its variation with bleaching
2017
Background Titanium is a less studied trace element in dental enamel. Literature relates an increased Titanium concentration with a decreased enamel crystal domain size, which in turn is related to a higher color value. The aim of our study was to analyze the effect of tooth bleaching agents on its concentration in dental enamel by means of confocal Raman spectroscopy. Material and methods Human teeth were randomly distributed in six experimental groups (n=10) and submitted to different bleaching protocols according to the manufacturer´s instructions. Confocal Raman spectroscopy was carried out in order to identify and quantify the presence of titanium dioxide molecules in enamel prior to a…
Influence de l'atmosphère gazeuse sur la cinétique de formation du titanate de baryum par réaction solide-solide
1986
International audience; Les études consacrées à la synthèse, par réaction solide-solide, du titanate de baryum (BaTiO3) ont montré l'importance des propriétés physicochimiques des solides initiaux (BaCO3 et TiO2) sur les propriétés du titanate obtenu. Lors de l'élaboration de céramiques diélectriques, il est en effet nécessaire d'éviter la formation de phases intermédiaires (Ba2TiO4, BaTi4O9, ...) qui nuisent à leurs propriétés diélectriques. La présence de ces phases peut être liée à une maîtrise imparfaite des nombreux paramètres influant sur la cinétique de la réaction. Le rôle de deux de ces paramètres : les traitements mécaniques et la nature de l'atmosphère gazeuse, fait l'objet de ce…
Corrosión galvánica entre implantes dentales y supraestructuras protésicas diseñadas con aleaciones de distinta naturaleza
2011
Introducción: La selección del material más adecuado para la fabricación de las estructuras de prótesis sobre implantes debe realizarse teniendo en cuenta sus propiedades mecánicas, su resistencia a la corrosión cuando se combina con titanio y su biocompatibilidad. En este sentido, las aleaciones nobles con alto contenido en oro han mostrado una excelente resistencia a la corrosión gracias a la elevada estabilidad termodinámica del oro en la aleación, como reportan múltiples estudios, por lo que han sido consideradas desde hace tiempo como el material de elección para la fabricación de prótesis sobre implantes. Sin embargo, su elevado coste ha originado el uso de otras aleaciones con difere…
Calculation of the effective charges of the atomic basins from ab initio Hartree-Fock electron densities in NaAlSi2O6 and NaTiSi2O6 pyroxenes
2005
Crystal structure of a rare trigonal bipyramidal titanium(IV) coordination complex: trichlorido(3,3′-di-tert-butyl-2′-hydroxy-5,5′,6,6′-tetramethyl-1…
2017
The title compound, [Ti(C24H33O2)Cl3(C4H8O)], is a rare example of a trigonal–bipyramidal titanium coordination complex with three chloride and two oxygen donor ligands. The asymmetric unit contains two independent molecules having essentially the same conformation. The molecules feature the titanium(IV) metal cation complexed with three chloride ligands, a tetrahydrofuran molecule, and one oxygen atom from the resolved ligand precursor (R)-(+)-5,5′,6,6′-tetramethyl-3,3′-di-t-butyl-1,1′-biphenyl-2,2′-diol, where the remaining phenolic hydrogen atom engages in intermolecular O—H...Cl hydrogen bonding. In one molecule, the THF ligand is disordered over two orientations with refined site occup…
CCDC 1917460: Experimental Crystal Structure Determination
2020
Related Article: A. Carel N. Kwamen, Marcel Schlottmann, David Van Craen, Elisabeth Isaak, Julia Baums, Li Shen, Ali Massomi, Christoph Räuber, Benjamin P. Joseph, Gerhard Raabe, Christian Göb, Iris M. Oppel, Rakesh Puttreddy, Jas S. Ward, Kari Rissanen, Roland Fröhlich, Markus Albrecht|2020|Chem.-Eur.J.|26|1396|doi:10.1002/chem.201904639
CCDC 1825458: Experimental Crystal Structure Determination
2018
Related Article: Quentin Bonnin, Sook-Yen Wong, Cedric Balan, Virginie Comte, Raluca Malacea, Marie-Jose Penouilh, Philippe Richard, Gerald Kehr, Adrien T. Normand, Gerhard Erker, Pierre Le Gendre|2018|Eur.J.Inorg.Chem.|2018|3813|doi:10.1002/ejic.201800636
CCDC 1985146: Experimental Crystal Structure Determination
2020
Related Article: Adrien T. Normand, E. Daiann Sosa Carrizo, Corentin Magnoux, Esteban Lobato, Hélène Cattey, Philippe Richard, Stéphane Brandès, Charles H. Devillers, Anthony Romieu, Pierre Le Gendre, Paul Fleurat-Lessard|2021|Chemical Science|12|253|doi:10.1039/D0SC04736H
CCDC 1825465: Experimental Crystal Structure Determination
2018
Related Article: Quentin Bonnin, Sook-Yen Wong, Cedric Balan, Virginie Comte, Raluca Malacea, Marie-Jose Penouilh, Philippe Richard, Gerald Kehr, Adrien T. Normand, Gerhard Erker, Pierre Le Gendre|2018|Eur.J.Inorg.Chem.|2018|3813|doi:10.1002/ejic.201800636