672 research outputs found
Kinetic study of niobium and tantalum hexameric forms and their substituted ions by capillary electrophoresis in alkaline medium
No full textIn this work a capillary electrophoretic (CE) method is used for the kinetic study of the intermetallic substitutions in hexameric ions of two strategic metals, tantalum and niobium in an alkaline medium. Recently proposed processes for the production and analytical separation of tantalum and niobium that are faster, more economical and environmental friendly are based on the use of highly alkaline media. It was previously established that in these media, tantalum and niobium exist as hexameric species, HxTa6O19X-8 (Ta6) and HxNb6019x-8 (Nb6), which can be analysed with a CE method using an alkaline electrolyte and UV detection. However, when using the above method on an industrial sample a minor species that should correspond to the substituted Ta1Nb5 form was observed. The purpose of the present study is to probe, by means of CE, the kinetic of the formation of substituted niobate-tantalate ions, Ta6-xNbx (1 ≤ x ≤ 5), starting from mixtures of pure hexaniobate and hexatantalate ions. This study required the development of a new CE method allowing the separation of all the five substituted ions and their two non-substituted hexameric parent ions in less than seven minutes. In details, a previously developed separation method was transferred to a Beckman instrument and the separation improved by adjusting the total length, the applied voltage, the injection volume, the rinsing steps and the internal standard. The kinetic study shows that samples initially containing non-substituted hexameric forms of tantalum and niobium in a 1:1M ratio naturally form the five possible substituted species Ta6-xNbx (1 ≤ x ≤ 5) after only a few hours which may represent an issue for future Nb-Ta separation processes operated in alkaline media. The developed method was also transferred to an Agilent instrument and the kinetic study repeated. Results obtained with the Agilent instrument corroborate those obtained with the Beckman instrument. The proposed electrophoretic separation method lays the ground for new analytical techniques that could help assessing the presence of substituted species that can be deleterious for Nb-Ta purification processes
Proxenoi e asylia nei Symbola di Gauthier
No full textIn the framework of a re-examination of Symbola, the volume dedicated by Gauthier to foreigners and justice, the author of this essay focuses his attention on chapter I, in particular on the figure and role of the proxenos (taking into account the main opinions subsequently expressed in literature), and on chapter V, in particular on the role of protection of the foreigner ensured by the grants of asylia. To clarify the scope of this privilege, it was deemed useful to compare the traditional way of understanding the sylai, i.e. the ‘saisies’ in Gauthier’s language, with the critique of this opinion carried out by B. Bravo in 1980. At the end of his analysis, the author holds the view that many of the research directions on these topics indicated by Gauthier, deserve to be taken into serious consideration by those who wish to continue the study of relations between citizens and foreigners in the Greek world.Nel quadro di un riesame di Symbola, il volume dedicato da Gauthier agli stranieri e la giustizia, l’autore del presente saggio concentra la sua attenzione, da un lato, sul capitolo I, in particolare sulla figura e sul ruolo del proxenos (tenendo conto delle principali opinioni espresse successivamente in dottrina), dall’altro, sul capitolo V, in particolare sul ruolo di protezione dello straniero assicurato dalle concessioni di asylia. Per chiarire la portata di tale privilegio si è ritenuto utile mettere a confronto il modo tradizionale di intendere le sylai, ossia le ‘saisies’ nel linguaggio di Gauthier, con la critica che di tale opinione ha svolto B. Bravo nel 1980. Si è potuto così constatare che molte delle direzioni di ricerca su questi argomenti, indicate da Gauthier, meritano di essere prese in seria considerazione da chi voglia approfondire in generale i rapporti fra cittadini e stranieri nel mondo greco
Spéciation du niobium et du tantale en milieux basiques et développement d’un procédé hydrométallurgique pour la séparation niobium-tantale
No full textNiobium (Nb) and tantalum (Ta) are two strategic elements for developed countries because of their unequalled properties and their use in several key sectors like the aerospace, fuel, building, nuclear, medical imaging or electronic industries. Due to their almost-identical chemical properties, the industrial processes currently used for the niobium-tantalum separation require strongly complexing media, like hydrofluoric acid. However, the high toxicity and the environmental footprint of these media force the industrials to develop new processes. In this regard, alkaline media represent a good alternative but the chemistry of Nb and Ta in such media is still poorly known. The objectives of this PhD thesis were to probe the speciation of Nb and Ta in alkaline aqueous solutions and to develop a new hydrometallurgical process able to perform the Nb-Ta separation. Firstly, new data were obtained on the speciation of Nb and Ta in alkaline media based on solubility measurements, UV-visible spectrophotometry, solid state NMR, Raman spectroscopy and capillary electrophoresis. Secondly, the information obtained from aqueous solutions (both synthetic and industrial) allowed us to develop an original solvent extraction process able to separate Nb and Ta without using any fluoride compound. This innovative process was tested at a pilot-scale (~ 1 L/h) on industrial solutions. The technical-economic evaluation of the developed process shows that this latter is profitable and economically competitive over the current industrial processes.Le niobium (Nb) et le tantale (Ta) sont deux éléments stratégiques pour les pays développés car ils sont difficilement substituables et utilisés dans de nombreux secteurs clés comme l’automobile, l’aéronautique, le nucléaire, le bâtiment, l’industrie pétrolière, l’imagerie médicale et l’électronique.La très grande similarité chimique du Nb et du Ta fait que les procédés industrialisés permettant leur séparation requièrent des milieux très complexants, comme les solutions d’acide fluorhydrique. Cependant, la toxicité et l’impact environnemental de ces solutions poussent les industriels à développer de nouveaux procédés. Les milieux alcalins peuvent être une alternative mais la chimie du Nb et du Ta à pH alcalin est encore peu connue à l’heure actuelle. Les objectifs de cette thèse étaient d’étudier la spéciation du Nb et du Ta dans les solutions aqueuses basiques et d’élaborer un procédé hydrométallurgique, sans fluor, pour la séparation niobium-tantale. Tout d’abord, de nouvelles données ont été acquises sur la spéciation du Nb et du Ta grâce à des mesures de solubilité, de spectrophotométrie UV-visible, de RMN du solide, de spectroscopie Raman et d’électrophorèse capillaire. Ensuite, les informations obtenues à partir de solutions aqueuses, synthétiques et industrielles, ont permis de développer un nouveau procédé d’extraction par solvant capable de séparer le Nb et le Ta et n’utilisant aucun réactif fluoré. Le procédé développé a également été testé et validé à l’échelle pilote (~ 1 L/h) sur des solutions industrielles. Enfin, l’étude technico-économique du procédé développé révèle que celui-ci sera rentable et compétitif par rapport aux procédés existants
Speciation of niobium and tantalum in alkaline media and development of a hydrometallurgical process for the niobium-tantalum separation
No full textLe niobium (Nb) et le tantale (Ta) sont deux éléments stratégiques pour les pays développés car ils sont difficilement substituables et utilisés dans de nombreux secteurs clés comme l’automobile, l’aéronautique, le nucléaire, le bâtiment, l’industrie pétrolière, l’imagerie médicale et l’électronique.La très grande similarité chimique du Nb et du Ta fait que les procédés industrialisés permettant leur séparation requièrent des milieux très complexants, comme les solutions d’acide fluorhydrique. Cependant, la toxicité et l’impact environnemental de ces solutions poussent les industriels à développer de nouveaux procédés. Les milieux alcalins peuvent être une alternative mais la chimie du Nb et du Ta à pH alcalin est encore peu connue à l’heure actuelle. Les objectifs de cette thèse étaient d’étudier la spéciation du Nb et du Ta dans les solutions aqueuses basiques et d’élaborer un procédé hydrométallurgique, sans fluor, pour la séparation niobium-tantale. Tout d’abord, de nouvelles données ont été acquises sur la spéciation du Nb et du Ta grâce à des mesures de solubilité, de spectrophotométrie UV-visible, de RMN du solide, de spectroscopie Raman et d’électrophorèse capillaire. Ensuite, les informations obtenues à partir de solutions aqueuses, synthétiques et industrielles, ont permis de développer un nouveau procédé d’extraction par solvant capable de séparer le Nb et le Ta et n’utilisant aucun réactif fluoré. Le procédé développé a également été testé et validé à l’échelle pilote (~ 1 L/h) sur des solutions industrielles. Enfin, l’étude technico-économique du procédé développé révèle que celui-ci sera rentable et compétitif par rapport aux procédés existants.Niobium (Nb) and tantalum (Ta) are two strategic elements for developed countries because of their unequalled properties and their use in several key sectors like the aerospace, fuel, building, nuclear, medical imaging or electronic industries. Due to their almost-identical chemical properties, the industrial processes currently used for the niobium-tantalum separation require strongly complexing media, like hydrofluoric acid. However, the high toxicity and the environmental footprint of these media force the industrials to develop new processes. In this regard, alkaline media represent a good alternative but the chemistry of Nb and Ta in such media is still poorly known. The objectives of this PhD thesis were to probe the speciation of Nb and Ta in alkaline aqueous solutions and to develop a new hydrometallurgical process able to perform the Nb-Ta separation. Firstly, new data were obtained on the speciation of Nb and Ta in alkaline media based on solubility measurements, UV-visible spectrophotometry, solid state NMR, Raman spectroscopy and capillary electrophoresis. Secondly, the information obtained from aqueous solutions (both synthetic and industrial) allowed us to develop an original solvent extraction process able to separate Nb and Ta without using any fluoride compound. This innovative process was tested at a pilot-scale (~ 1 L/h) on industrial solutions. The technical-economic evaluation of the developed process shows that this latter is profitable and economically competitive over the current industrial processes
L\u27Irlande de Georges Dor, Jacques Ferron et Louis Gauthier
No full textDans ce travail, l\u27auteur étudie trois romans d\u27auteurs québécois et aborde les liens qu\u27ils établissent entre l\u27Irlande et le Québec. L\u27étude s\u27intéressa aux rapprochements que l\u27on peut établir entre ces deux territoires et la manière dont ils sont représentés dans la littérature de Georges Dor, Jacques Ferron et Louis Gauthier et plus particulièrement dans les romans : Le fils de l\u27Irlandais, Le salut de l\u27Irlande et Voyage en Irlande avec un parapluie.
In this thesis, the author studies three books of Québécois authors and discusses the links that each one makes between Ireland and Quebec. This study looks at the relations that can be established between these two territories and the style in which they are represented in the works of Georges Dor, Jacques Ferron and Louis Gauthier, specifically in the books: Le fils de l\u27Irlandais, Le salut de l\u27Irlande and Voyage en Irlande avec un parapluie
Spéciation du niobium et du tantale en milieux basiques et développement d’un procédé hydrométallurgique pour la séparation niobium-tantale
No full textNiobium (Nb) and tantalum (Ta) are two strategic elements for developed countries because of their unequalled properties and their use in several key sectors like the aerospace, fuel, building, nuclear, medical imaging or electronic industries. Due to their almost-identical chemical properties, the industrial processes currently used for the niobium-tantalum separation require strongly complexing media, like hydrofluoric acid. However, the high toxicity and the environmental footprint of these media force the industrials to develop new processes. In this regard, alkaline media represent a good alternative but the chemistry of Nb and Ta in such media is still poorly known. The objectives of this PhD thesis were to probe the speciation of Nb and Ta in alkaline aqueous solutions and to develop a new hydrometallurgical process able to perform the Nb-Ta separation. Firstly, new data were obtained on the speciation of Nb and Ta in alkaline media based on solubility measurements, UV-visible spectrophotometry, solid state NMR, Raman spectroscopy and capillary electrophoresis. Secondly, the information obtained from aqueous solutions (both synthetic and industrial) allowed us to develop an original solvent extraction process able to separate Nb and Ta without using any fluoride compound. This innovative process was tested at a pilot-scale (~ 1 L/h) on industrial solutions. The technical-economic evaluation of the developed process shows that this latter is profitable and economically competitive over the current industrial processes.Le niobium (Nb) et le tantale (Ta) sont deux éléments stratégiques pour les pays développés car ils sont difficilement substituables et utilisés dans de nombreux secteurs clés comme l’automobile, l’aéronautique, le nucléaire, le bâtiment, l’industrie pétrolière, l’imagerie médicale et l’électronique.La très grande similarité chimique du Nb et du Ta fait que les procédés industrialisés permettant leur séparation requièrent des milieux très complexants, comme les solutions d’acide fluorhydrique. Cependant, la toxicité et l’impact environnemental de ces solutions poussent les industriels à développer de nouveaux procédés. Les milieux alcalins peuvent être une alternative mais la chimie du Nb et du Ta à pH alcalin est encore peu connue à l’heure actuelle. Les objectifs de cette thèse étaient d’étudier la spéciation du Nb et du Ta dans les solutions aqueuses basiques et d’élaborer un procédé hydrométallurgique, sans fluor, pour la séparation niobium-tantale. Tout d’abord, de nouvelles données ont été acquises sur la spéciation du Nb et du Ta grâce à des mesures de solubilité, de spectrophotométrie UV-visible, de RMN du solide, de spectroscopie Raman et d’électrophorèse capillaire. Ensuite, les informations obtenues à partir de solutions aqueuses, synthétiques et industrielles, ont permis de développer un nouveau procédé d’extraction par solvant capable de séparer le Nb et le Ta et n’utilisant aucun réactif fluoré. Le procédé développé a également été testé et validé à l’échelle pilote (~ 1 L/h) sur des solutions industrielles. Enfin, l’étude technico-économique du procédé développé révèle que celui-ci sera rentable et compétitif par rapport aux procédés existants
Guerre du blé, guerre du droit
No full textWhat the historiography of the French Revolution as forgotten is the reflexion on the rights of men, the first of which is the one which guarantees life. Against an economist and determinist vision, the author re-estimates the place of the peasantry in the process of liberation of 1789.Gauthier Florence, EspaceTemps. Guerre du blé, guerre du droit. In: Espaces Temps, 38-39, 1988. Concevoir la révolution. 89, 68, confrontations. pp. 113-114
The contextual database of the generations and gender program in Bulgaria: conceptual framework and an overview of the Bulgarian context concerning the central database topics
No full textThis paper outlines the concept and content of the Contextual Database of the international Generations and Gender Program and gives an overview of the context of demographic behavior in Bulgaria. The Contextual Database provides an instrument that together with the Generations and Gender Survey allows studying how differences in context shape demographic processes. The database offers the opportunity to analyze in a comparative way the interaction between the micro and macro dimension. Bulgaria is among the first countries fielding the Generations and Gender Survey and that is engaged in contextual data collection within this comparative framework. While both micro- and contextual data for Bulgaria will become available in the course of the year 2005, we present in this paper a text contribution that provides an overview of the Bulgarian context and introduces the list of variables that make up the database.Bulgaria, data collection
RabbitStamp Test Sequence
No full text# RabbitStamp sequence by LISA ULB
The test sequence "RabbitStamp" is provided by Sarah Fachada, Yupeng Xie, Daniele Bonatto, Gauthier Lafruit, Mehrdad Teratani, members of the LISA department, EPB (Ecole Polytechnique de Bruxelles), ULB (Universite Libre de Bruxelles), Belgium.
# License:
CC BY-NC-SA
ONLY Available for Academic Usage
# Terms of Use:
Anykind of publication or report using this sequence should refer to the following references.
[1] Sarah Fachada, Yupeng Xie, Daniele Bonatto, Gauthier Lafruit, Mehrdad Teratani, "RabbitStamp Test Sequence", 2021.
@misc{fachada_RabbitStamp_2021,
title = {{RabbitStamp} {Test} {Sequence}},
author = {Fachada, Sarah and Xie; Yupeng and Bonatto, Daniele and Lafruit, Gauthier and Teratani, Mehrdad },
month = jul,
year = {2021},
doi = {10.5281/zenodo.5053771}
}
[2] Sarah Fachada, Yupeng Xie, Daniele Bonatto, Gauthier Lafruit, Mehrdad Teratani, "[DLF] Plenoptic 2.0 Multiview Lenslet Dataset and Preliminary Experiments [m56429]", 2021.
@article{fachada_RabbitStamp_2021,
title = {[DLF] {Plenoptic} 2.0 {Multiview} {Lenslet} {Dataset} and {Preliminary} {Experiments} [m56429]},
author = {Fachada, Sarah and Xie; Yupeng and Bonatto, Daniele and Lafruit, Gauthier and Teratani, Mehrdad },
journal = {ISO/IEC JTC1/SC29/WG11},
month = apr,
year = {2021}
}
[3] Sarah Fachada, Yupeng Xie, Daniele Bonatto, Gauthier Lafruit, Mehrdad Teratani, "[LVC] Update for RabbitStamp: Plenoptic 2.0 Multiview Lenslet Dataset [m57100]", 2021.
@article{fachada_RabbitStamp_2021,
title = {[LVC] {Update} for {RabbitStamp}: {Plenoptic} 2.0 {Multiview} {Dataset} [m56429]},
author = {Fachada, Sarah and Xie; Yupeng and Bonatto, Daniele and Lafruit, Gauthier and Teratani, Mehrdad },
journal = {ISO/IEC JTC1/SC29/WG11},
month = jul,
year = {2021}
}
[4] Sarah Fachada, Yupeng Xie, Daniele Bonatto, Gauthier Lafruit, Mehrdad Teratani, "[LVC] Exploration Experiments using RabbitStamp Multiview Lenslet Images [m57101]", 2021.
@article{fachada_RabbitStamp_2021,
title = {[LVC] {Exploration} {Experiments} {Using} {RabbitStamp} {Multiview} {Lenslet} {Images} [m56429]},
author = {Fachada, Sarah and Xie; Yupeng and Bonatto, Daniele and Lafruit, Gauthier and Teratani, Mehrdad},
journal = {ISO/IEC JTC1/SC29/WG11},
month = jul,
year = {2021}
}
# Production:
Laboratory of Image Synthesis and Analysis, LISA department, Ecole Polytechnique de Bruxelles, Universite Libre de Bruxelles, Belgium.
# Content:
This dataset contains a test scene acquired with a raytrix camera [1] array of 7x3 views. For details of the dataset, please refer to the references mentioned above.
The dataset contains:
- a `depth_7x3_center` depth maps computed with DERS reference software [2] in yuv40016ble format and json configuration files to do so,
- a `multiview_7x3_5x5_images` Calibrated subimages computed with RLC [3] in yuv42010ble format, the cameras.json with the camera parameters and view_synthesis.json with the view synthesis experiment.
- a `multiview_7x3_lenslets` folder containing the lenslet views in yuv42010ble format, the Raytrix xml calibration file and RLC cfg file for conversion to multiview.
# References and links:
[1] Raytrix, https://raytrix.de/
[2] S. Rogge and D. Bonatto and J. Sancho and R. Salvador and E. Juarez and A. Munteanu and G. Lafruit, "MPEG-I Depth Estimation Reference Software", in 2019 International Conference on 3D Immersion (IC3D), 2019.
[3] M. Teratani and T. Fujii, "[MPEG-I Visual] Conversion of Lenslet Data Capture by Single Focussed Plenoptic Camera to Multiview Video using RLC0.3 [N18567]", ISO/IEC JTC1/SC29/WG11, 201
Synthesis and structural characterization of a hydrated sodium–caesium tetracosatungstate(VI), Na5Cs19[W24O84]·21H2O
No full textCrystal formation of pentasodium nonadecacesium tetracosatungstate(VI) heneikosahydrate, Na5Cs19[W24O84]·21H2O, was successfully achieved by the conversion of [H2W12O42]10− through the addition of excess Cs+. The crystal structure comprising the toroidal isopolyoxidometalate is presented, as well as its Raman spectrum. Na5Cs19(H2O)21W24O84 crystallizes in the rhombohedral space group R\overline{3} with an obverse centering. The title compound represents the addition of a new member to the isopolytungstate family with mixed alkali counter-ions and contains rarely observed five-coordinate tungsten(VI) atoms in the [W24O84]24− anion (site symmetry C3i) arising from the conversion mediated by Cs+ counter-ions
- …
