Relevant bibliographies by topics / Oxydes à base de Co

Contents

  1. Journal articles
  2. Dissertations / Theses
  3. Books
  4. Book chapters
  5. Conference papers
  6. Reports

Academic literature on the topic 'Oxydes à base de Co'

Author: Grafiati
Published: 25 May 2024

Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles

Select a source type:

Consult the lists of relevant articles, books, theses, conference reports, and other scholarly sources on the topic 'Oxydes à base de Co.'

Next to every source in the list of references, there is an 'Add to bibliography' button. Press on it, and we will generate automatically the bibliographic reference to the chosen work in the citation style you need: APA, MLA, Harvard, Chicago, Vancouver, etc.

You can also download the full text of the academic publication as pdf and read online its abstract whenever available in the metadata.

Journal articles on the topic "Oxydes à base de Co"

1

BAL, Mustafa. "Synthesis and Characterization of Tetradentate Schiff Base Ligand Containing 3,4-Diamino Benzophenone and Investigation of Complex Formation with Ni (II), Cu (II) and Co (II) metal ions." Cumhuriyet Science Journal 44, no. 2 (June 30, 2023): 289–95. http://dx.doi.org/10.17776/csj.1210668.

Full text
Abstract:
Compound that is a novel tetradentate Schiff base ligand [(3,4-bis(((E)-4-(diethylamino)-2-hydroxybenzylidene)amino)phenyl)(phenyl) methanone] (1), 4-(diethylamino) It was synthesized by the reaction of (3,4-diaminophenyl)(phenyl)methanone with -2-hydroxybenzaldehyde. Complex reactions with Co(II) (1a), Cu(II) (1b) and Ni(II) (1c) metals were prepared based on the obtained Schiff base ligand. The synthesized Schiff base and its Ni(II), Cu(II) and Co(II) complexes were featured using FT-IR, UV-vis, photoluminescence, mass and 1H and 13C-NMR spectroscopy. The characterization processes show that the tetradentate Schiff base compound coordinates with metal ions, oxygen of the hydroxyl group and nitrogen of the azomethine group.
APA, Harvard, Vancouver, ISO, and other styles
2

Li, Qu, Jing Liang, Dong Teng Long, Wei Liang Cheng, Chang Qing Dong, and Jun Jiao Zhang. "Research on Chemical Materials with Characteristic on Chemical Looping Combustion of Co-Doped Fe2O3 Oxygen Carrier with CO." Applied Mechanics and Materials 540 (April 2014): 30–34. http://dx.doi.org/10.4028/www.scientific.net/amm.540.30.

Full text
Abstract:
Co-doped Fe2O3 oxygen carriers reacted with CO were investigated in order to study the temperature effect on the redox characterization.Co-Fe2O3 were characterized with X-ray diffraction (XRD), BET and transmission electron microscope (TEM), which showed that the surface structure was regular, and the polymorph was stable. The TG (Thermo Gravimetric Analyzer) analysis indicted that, rational doping Co could enhance the reactivity of iron-base oxygen carrier reacted with CO under different conditions. Oxygen carrier with Fe: Co molar ratio of 1:0.1 had best reactivity. With the temperature increased, the reduction degree became deeper and the complete conversion time shortened. The reduction reaction Co0.1Fe oxygen carrier with CO was carried out step by step, and the entire process was divided into three stages, namely 344.7-391.0, 414.7-472.5 and 607.6-681.5°C.
APA, Harvard, Vancouver, ISO, and other styles
3

Bhowmik, K. R. Nath Bhowmik, R. N. Dutta Purkayastha, and S. Roy. "Synthesis, Structural Characterization, Reactivity and Bioactivity Studies of Some Binuclear Salen Type Schiff Base Complexes of Manganese(III)." Asian Journal of Chemistry 36, no. 3 (February 28, 2024): 690–96. http://dx.doi.org/10.14233/ajchem.2024.31074.

Full text
Abstract:
Four new phenoxy bridged binuclear Salen type Schiff base complexes of manganese(III), [MnLX]2 with tetradentate Schiff base, H2L [H2L = N,N′-O-phenylene bis(salicylaldimine)] containing anionic co-ligands, X (X = benzoate, p-hydroxy benzoate, p-aminobenzoate, 3,5-dinitrobenzoate) have been synthesized from manganese(II) acetate, Schiff base (H2L) and the corresponding co-ligands in methanol medium. Schiff base ligand (H2L) was obtained in situ by condensation of salicylaldehyde and o-phenylenediamine in aqueous methanol. Elemental analyses, FT-IR, molar conductance, UV-visible spectroscopic studies and magnetic moment measurements at room temperature were used to characterize the binuclear Schiff base complexes. The IR spectra of [MnLX]2 (X = benzoate, p-hydroxy benzoate, p-aminobenzoate, 3,5-dinitrobenzoate) complexes showed the characteristic absorptions due to coordinated azomethine nitrogen and phenolic oxygen atoms of the Schiff base. In addition, IR spectra of the compounds also suggest coordination of the co-ligands namely benzoate, p-hydroxy benzoate, p-aminobenzoate, 3,5-dinitrobenzoate in the respective complexes. A consistent presence of a band at ca. 755 cm-1 in all the binuclear complexes arises due to (Mn-O-Mn) moiety originated from interactions of phenoxy oxygen and manganese atoms, resulted in dimeric structure of the compounds. The magnetic moment values ranging from 4.74-4.91 B.M. per manganese centre for the complexes suggest presence of Mn(III) ion in the complexes. The overall coordination geometry around the manganese centres is distorted octahedral. Redox behaviour of the synthesized complexes was ascertained from cyclic voltametric studies. The Schiff base complexes, [Mn(L)X]2 (X = p-aminobenzoate, 3,5-dinitrobenzoate) have demonstrated their catalytic potentials in oxidizing selective organic substrates namely cyclohexene and styrene by hydrogen peroxide as oxidant. The oxidized products were characterized as trans-cyclohexane 1,2-diol and styrene epoxide, respectively. Complex 4 demonstrated a considerable level of effectiveness against a wide variety of pathogenic microorganisms.
APA, Harvard, Vancouver, ISO, and other styles
4

Li, Qu, Chang Feng Lin, Jun Jiao Zhang, Wei Liang Cheng, and Wu Qin. "Experimental Investigation of Chemical Looping Combustion of CO with Fe-Based Oxygen Carrier." Advanced Materials Research 986-987 (July 2014): 72–75. http://dx.doi.org/10.4028/www.scientific.net/amr.986-987.72.

Full text
Abstract:
Reaction activities of Ni-doped and Cu-doped Fe2O3 oxygen carriers (OCs) with CO were investigated using thermo gravimetric (TG-DTG).The structures of the prepared OC were characterized by X-ray diffract meter (XRD).TG-DTG investigations indicated that rational Ni and Cu doping could efficiently enhance the reactivity of Fe-base oxygen carrier for oxidizing CO under different conditions. And Fe-based OC doped with 20 wt. % Ni can realize the highest reactivity.
APA, Harvard, Vancouver, ISO, and other styles
5

Mendu, Padmaja, J. Pragathi, B. Anupama, and C. Gyana Kumari. "Synthesis, Spectral Characterization, Molecular Modeling, and Antimicrobial Studies of Cu(II), Ni(II), Co(II), Mn(II), and Zn(II) Complexes of ONO Schiff Base." E-Journal of Chemistry 9, no. 4 (2012): 2145–54. http://dx.doi.org/10.1155/2012/839789.

Full text
Abstract:
A series of Cu(II), Ni(II), Co(II), Mn(II), and Zn(II) complexes have been synthesized from the schiff base ligand L. The schiff base ligand [(4-oxo-4H-chromen-3-yl) methylene] benzohydrazide (L) has been synthesized by the reaction between chromone-3-carbaldehyde and benzoyl hydrazine. The nature of bonding and geometry of the transition metal complexes as well as schiff base ligand L have been deduced from elemental analysis, FT-IR, UV-Vis,1HNMR, ESR spectral studies, mass, thermal (TGA and DTA) analysis, magnetic susceptibility, and molar conductance measurements. Cu(II), Ni(II), Co(II), and Mn(II) metal ions are forming 1:2 (M:L) complexes, Zn(II) is forming 1:1 (M:L) complex. Based on elemental, conductance and spectral studies, six-coordinated geometry was assigned for Cu(II), Ni(II), Co(II), Mn(II), and Zn(II) complexes. The complexes are 1:2 electrolytes in DMSO except zinc complex, which is neutral in DMSO. The ligand L acts as tridentate and coordinates through nitrogen atom of azomethine group, oxygen atom of keto group ofγ-pyrone ring and oxygen atom of hydrazoic group of benzoyl hydrazine. The 3D molecular modeling and energies of all the compounds are furnished. The biological activity of the ligand and its complexes have been studied on the four bacteriaE. coli, Edwardella, Pseudomonas, andB. subtilisand two fungipencilliumandtricodermaby well disc and fusion method and found that the metal chelates are more active than the free schiff base ligand.
APA, Harvard, Vancouver, ISO, and other styles
6

Siraj, I. T., and M. Sule. "Synthesis, characterisation and antimicrobial activities of mixed ligand complexes of Mn (II), Fe (II) and Co(II) containing N,N'-bis (o-anisaldehyde) p-phenylenediamine (tetradentate schiff base) and gylcine." Bayero Journal of Pure and Applied Sciences 11, no. 1 (October 11, 2018): 32–36. http://dx.doi.org/10.4314/bajopas.v11i1.6.

Full text
Abstract:
Complexes of Mn(II), Fe(II) and Co(II) containing N, N’-bis[o-anisaldehyde]p-phenylenediamine tetradentate Schiff base as primary ligand and glycine as secondary bidentate ligand have been synthesized by reflux in 1:1:1 mole ratio and characterized both analytically and spectroscopically. Molar conductance measurement (69.02 to 86.30Ω–1 cm2 mol–1) of the complexes indicated they are weak electrolyte and magnetic susceptibility measurement shows values in range of 4.53 to 5.59BM indicating their paramagnetism. The infrared data suggested that the Schiff base coordinated via the two nitrogen atoms of the azomethine groups (1628 to 1680 cm-1) and the oxygen atoms of the adjacent methoxy groups (1341 to 1389 cm-1), while glycine coordinated via the nitrogen atom of the amino group (3060-3324 cm-1) and the oxygen atom of the carboxylate anion. Based on the analytical and spectroscopic data the complexes may be assigned an octahedral geometries and molecular formulae of the form [M(L)Gly], where M = Mn, Fe and Co, L=Schiff base and Gly = glycine. The Schiff base and its mixed ligand complexes were screened for antimicrobial activity against Staphylococcus aureus, Escherichia coli, Salmonella typhi, Mucor inducus and Aspergillus fumigatus. The complexes exhibited enhanced antimicrobial activity (10mm to 18mm) at 60 µg/disc as compared to 10mm activity of the uncoordinated Schiff base at the same concentration.Keywords: Mixed ligand complex; Schiff base, Glycine, p-phenylenediamine, o-anisaldehyde
APA, Harvard, Vancouver, ISO, and other styles
7

Wagh, Shaila, and B. R. Patil. "SYNTHESIS, SPECTRAL, THERMAL AND ANTIMICROBIAL STUDIES OF NEW METAL COMPLEXES OF SUBSTITUTED HYDROXY PROPIOPHENONE." RASAYAN Journal of Chemistry 15, no. 03 (2022): 1718–27. http://dx.doi.org/10.31788/rjc.2022.1536355.

Full text
Abstract:
A new series of metal complexes of innovative bisketimines (L1 - L5) have been synthesized. Schiff base ligands were synthesized by condensing substituted 2’- hydroxy propiophenone and ethylene diamine. The synthesized Schiff bases act as tetradentate ligands with two nitrogen and two phenolic oxygen groups and co-ordinates with Co (II), Ni (II), Cu (II) and Zn (II) salts. Ligands and their metal complexes have been studied using 1H NMR, IR, UV-Vis and thermogravimetric techniques. The complexes were crystalline, according to the XRD pattern. The thermogravimetric data revealed the thermal stability of the complexes. The study of antibacterial and antifungal activities of the ligands and their metal complexes showed more effectiveness of metal complexes than Schiff base ligands.
APA, Harvard, Vancouver, ISO, and other styles
8

Al-Wasidi, Asma S., Ahmed M. Naglah, Mohamed A. Al-Omar, Abdul-Rahman M. Al-Obaid, Eid H. Alosaimi, Nashwa M. El-Metwaly, Moamen S. Refat, et al. "Manganese (II), ferric (III), cobalt (II) and copper (II) thiosemicarbazone Schiff base complexes: Synthesis, spectroscopic, molecular docking and biological discussions." Materials Express 10, no. 2 (February 1, 2020): 290–300. http://dx.doi.org/10.1166/mex.2020.1636.

Full text
Abstract:
Mn(II), Fe(III), Co(II) and Cu(II) Schiff base complexes with general formula ML−2 .nH2O (where M is a respected metal ions and L−2 is the Schiff base). The Schiff base (L = TSCPA) was formed by the condensation of thiosemicarbazide and phthalic anhydride in acetic acid. The microanalytical analysis confirmed the 1:1 (metal: ligand) molar ratio. Magnetic susceptibility and electronic absorption spectra were suggested that the Fe(III) and Co(II) complexes were octahedral structure but the Mn(II) and Cu(II) complexes were tetrahedral geometry. FTIR spectra reveal that the ligand exists, predominantly, as keto form in a solid state but as enol form in the alkaline medium. The coordination between TSCPA chelate and central metal ions take place through nitrogen –NH, sulphur C=S and oxygen –OH groups. Based on the molar conductance measurements the complexes may be formulated as [Mn(L)(H2O)] · 4H2O, [Fe(L)(Cl)(H2O)2] · 2H2O, [Co(L)(H2O)3] · 3H2O and [Cu(L)(H2O)] · 4H2O due to their non-electrolytic behavior. The Schiff base ligand and their metal complexes were screened in vitro against G(+Ve) and G(−Ve) bacteria. This study came after proactive step, which concerning with docking study against pathogen proteins corresponding to microorganisms for bacteria and fungi, which will be scanned in vitro study. Thermogravimetry (TGA) and differential thermogravimetry (DTG) were discussed.
APA, Harvard, Vancouver, ISO, and other styles
9

Pająk, Marek, Magdalena Woźniczka, Marta E. Lichawska, Bartłomiej Czerwiński, Jakub Włodarczyk, and Jakub Fichna. "Oxygen Binding by Co(II) Complexes with Oxime-Containing Schiff Bases in Solution." International Journal of Molecular Sciences 23, no. 10 (May 14, 2022): 5492. http://dx.doi.org/10.3390/ijms23105492.

Full text
Abstract:
The present work describes the complexation properties of two oxime-containing Schiff bases (used as ligands), viz. 2-hydroxyimino-N′-[1-(2-pyridyl)ethylidene]propanohydrazone (Hpop) and 2-hydroxyimino-N′-[(pyridine-2-yl)methylidene]propanohydrazone (Hpoa), with Co(II) ions in DMSO/water solution. Volumetric (oxygenation) studies were carried out to determine the uptake of molecular oxygen O2 in the formation of the complexes Co(II)-Hpop and Co(II)-Hpoa. The acquired data can be useful in the development of oxygen bioinorganic complexes of metal ions with Schiff base ligands in solution. Their properties allow them to be used as synthetic oxygen transporters. Moreover, the binding of dioxygen could play an important role in the research of catalytic activity by such systems.
APA, Harvard, Vancouver, ISO, and other styles
10

Gao, Jinhao, Shuling Liu, Zhijian Li, Yichuang Xing, Xian Cui, and Chao Wang. "Cobalt Phosphide Nanoparticles Synthesized by Solvothermal Phosphidization of Metal-Organic Frameworks for Electrocatalytic Oxygen Evolution." International Journal of Energy Research 2023 (February 7, 2023): 1–12. http://dx.doi.org/10.1155/2023/3893229.

Full text
Abstract:
Active and stable electrocatalysts for oxygen evolution reaction (OER) are crucial in the widespread application of water electrolyzers. Cobalt phosphide nanoparticles (Co-P) with different degrees of crystallinity are synthesized via solvothermal phosphidization of Co metal-organic frameworks and P4 using different solvents. The Co-P can be converted to active OER electrocatalysts in 1 M KOH, with the most active reaching 10 mA cm-2 OER current densities at 270 mV overpotential. The OER intermediate adsorption energy is tuned by the electron interactions in the crystalline/amorphous heterostructured Co-P, which show the highest intrinsic OER activity. After the long-term OER in base, surface phosphides are converted to (oxy)hydroxides that are the active species towards OER.
APA, Harvard, Vancouver, ISO, and other styles
More sources

Dissertations / Theses on the topic "Oxydes à base de Co"

1

Dathy, Corinne. "Activité et sélectivité de catalyseurs à base de métaux nobles et/ou de carbures et nitrures dans les réactions CO, NO en catalyse de post-combustion automobile." Lille 1, 1993. http://www.theses.fr/1993LIL10152.

Full text
Abstract:
Ce travail de these porte sur l'etude des reactions de reduction des oxydes d'azote par le monoxyde de carbone qui est une reaction modele d'elimination de ces polluants en catalyse de post-combustion automobile. Dans une premiere partie, la determination de l'activite et de la selectivite de catalyseurs de reference a base de platine et de rhodium sur alumine dans les reactions co+no (avec ou sans oxygene) ont mis en relief les modifications apportees par l'adjonction du rhodium au platine en precisant leurs caracteristiques propres; de meme, les variations de reactivite du catalyseur bimetallique pt-rh/al#2o#3 ont ete observees avant et apres, l'addition de promoteur d'oxyde de cerium qui joue un role important dans les pots catalytiques. Ces etudes ont permis de verifier et de preciser le mecanisme reactionnel selon le modele propose par harrison et coll. D'autre part, la selectivite en oxyde nitreux (n#2o) (polluant nocif pour la couche d'ozone et contribuant a l'effet de serre) a ete systematiquement suivie experimentalement. Nous avons pu ainsi montrer que n#2o est un produit primaire de reaction et que la transformation de no en azote se fait selon des reactions successives. Dans une deuxieme partie, nous nous somme attaches a rechercher des catalyseurs a base de carbures et de nitrures soit en tant que phases actives, possibles substituts des metaux nobles, soit en tant que supports autres que l'alumine pour modifier la reactivite du platine et du palladium. Enfin, l'etude des catalyseurs pt et pd supportes sur carbure de chrome et nitrure de silicium fait apparaitre un comportement catalytique different de celui de ces metaux supportes sur alumine probablement du a la modification des proprietes chimisorptives des metaux en interaction avec des supports non oxydes.
APA, Harvard, Vancouver, ISO, and other styles
2

Derrouiche, Salim. "Approche micro cinétique des réactions CO/O2 et CO/NO sur des catalyseurs à base de Pt et Rh supportés : expériences et modélisations." Lyon 1, 2006. http://www.theses.fr/2006LYO10118.

Full text
Abstract:
L'objectif du travail relève d'une approche micro cinétique expérimentale des réactions CO/O2 et CO/NO sur des catalyseurs Pt et Rh supportés. Dans un premier temps nous avons utilisé un modèle cinétique précédemment établi au laboratoire pour la réaction CO/O2 sur Pt/Al2O3 en vue de déterminer l'impact de la dispersion D du Pt sur le TOF de la réaction ainsi que les étapes élémentaires impliquées. Ceci nous a permis de corréler ces observations à la modification des étapes élémentaires. Des études menées en régimes transitoires lors de l'oxydation par O2 des espèces CO adsorbées indiquent une période d'induction dans la formation du CO2 observée uniquement pour D>0. 6. L'impact de divers paramètres expérimentaux a, à cet effet, été réalisé et un jeu d 'équations mathématiques a été établi modélisant correctement les données expériementales. Ces études montrent que la compétition d'adsorption entre les espèces CO-B et oxygènes faiblement adsorbés (Owads) constituent un processus clé dans l'observation d'une période d'induction. La procédure AEIR, appuyée de la spectroscopie FTIR, a été utilisée à l'étude de l'impact de divers paramètres sur la chaleur d'adsorption d'espèces CO adsorbées sur différents catalyseurs supportés. C'est dans l'objectif de déterminer celle d'espèces inactives en IR qu'une nouvelle méthode a été développée : TPAE. Dans un second temps, nous avons étudié l'impact de la présence de NO sur la réaction CO/O2. Des expériences menées par spectroscopie FTIR et spectrométrie de masse suggèrent que ce sont les espèces Nads, provenant de la dissociation de NO, qui perturbent la réaction d'oxydation des espèces CO adsorbées. Enfin, en préliminaire d'une modélisation cinétique des réactions CO/O2 sur Rh/Al2O3 d'une part et CO/NO sur Pt/Al2O3 et Rh/Al2O3, nous avons entrepris des expériences en régimes transitoires par une approche similaire à celles de CO/O2 sur Pt/Al2O3. En comparaison avec cette dernière, il est observé que la réaction CO/O2 sur Rh/Al2O3 exhibe de grandes ressemblances. Toutefois, la formation d'espèces gem di-carbonyls complique l'exploitation des données. Quant à la réaction CO/NO sur les deux catalyseurs, il apparaît que la vitesse d'oxydation par NO est plus lente que sous O2
APA, Harvard, Vancouver, ISO, and other styles
3

Liao, Xuemei. "Catalyseurs à base d'or supporté sur des oxydes minéraux pour la réaction d'oxydation préférentielle du monoxyde de carbone en présence d'hydrogène (PROX)." Thesis, Strasbourg, 2013. http://www.theses.fr/2013STRAF053.

Full text
Abstract:
L’activité catalytique de l’or en réaction d’oxydation préférentielle du CO (PROX) dépend de plusieurs facteurs tels que la nature du support, l’ajout de promoteurs, la taille des particules ou la nature du prétraitement. L’objectif de cette thèse a donc été de clarifier l’influence de ces paramètres sur cette réaction en utilisant des catalyseurs à base d’or modifiés. Dans une 1ère partie, nous avons étudié un système à base d’or supporté sur des oxydes Ce-Fe préparés par co-imprégnation ou imprégnations successives en faisant varier le rapport Ce/Fe. Le dopage de la cérine par le fer conduit à la formation d’une solution solide qui améliore l’activité en PROX en raison d’une mobilité d’oxygène accrue. Dans une 2ème partie, nous avons évalué une série de supports (Al2O3, CeO2 et Ce2Zr2O7) pour optimiser le dépôt de Au, Cu ou Au-Cu. La combinaison Au-Cu/CeO2 s’est révélée être la meilleure en PROX. Nous avons donc étudié l’influence du rapport Au/Cu (1/3, 1/1 ou 3/1) ainsi que l’influence du pré-traitement (calcination ou réduction) sur ce système. Les catalyseurs ont été systématiquement caractérisés par des méthodes physico-chimiques (BET, DRX, MET, XPS, RTP, FTIR). Les performances catalytiques du système Au-Cu/CeO2 dépendent fortement de la taille des particules, de l’état chimique de l’or déterminé par XPS, de l’interaction Au-support et de la distribution de surface des 2 métaux. Une étude cinétique corrélée à de l’infrarouge à transformée de Fourier a permis d’établir un mécanisme de réaction d’oxydation de CO dans le lequel CO adsorbé réagit avec O2 adsorbé pour conduire à la formation de CO2
The catalytic activity of gold for CO preferential oxidation in rich hydrogen (PROX) is generally influenced by various parameters such as the nature of support, the addition of a promoter, the particle size or the pre-treatment. Therefore, the objectives of this work were to clarify the influence of these parameters on a series of modified gold catalysts in PROX reaction. In a 1rst part, we have studied a system based on Au supported on Ce-Fe oxides prepared by co-precipitation or impregnation with various Ce/Fe ratios. The doping of CeO2 by iron led to the formation of a solid solution which improved the PROX activity due to an increase of the oxygen mobility. In a 2nd part, a series of supports (Al2O3, CeO2, and Ce2Zr2O7) was evaluated in order to load Au, Cu or Au-Cu. The combination of Au-Cu/CeO2 was shown to be the best system. The influence of Au/Cu (1/3, 1/1 or 3/1) ratio was therefore undertaken along with the effect of the pre-treatment (calcination or reduction). The catalysts have been systematically characterized by physico-chemical techniques (BET, XRD, TEM, XPS, TPR, FTIR). The kinetics of PROX reaction and CO oxidation mechanism on Au-Cu/CeO2 were explored and correlated with an FTIR study. The catalytic performances of these catalysts are strongly dependent upon the particle size of the metal, the chemical state of gold, the gold-support interaction and the surface distribution of Au and Cu. We have proposed a CO oxidation mechanism in which adsorbed CO reacts with adsorbed O2 to produce CO2
APA, Harvard, Vancouver, ISO, and other styles
4

Delmaire, Florence. "Caractérisation de Bi4V2O11 et de quelques Bi4(V1-xMex)2O11- δ(Me=Cu, Ni, Co, Zn) par des techniques physicochimiques et tests catalytiques." Lille 1, 1997. http://www.theses.fr/1997LIL10020.

Full text
Abstract:
Le vanadate de bismuth pur (bi4v2o11) ou dope (bi4 (v1-x mex)2 o11- me = cu, ni, co, zn. . . ) Obtenu par synthèse a l'état solide fait partie des matériaux présentant une forte conductivité anionique par migration d'ions o2-. Sa structure dérive de la phase d'aurivillius bi2moo6 et peut être décrite comme un empilement de couches (bi2o2)2+ selon l'axe c entre lesquelles s'intercalent des feuillets de type pérovskite (vo3,5)2-. L'oxyde pur bi4v2o11 présente plusieurs phases cristallines selon la température. La phase , la plus conductrice, observée à haute température, peut être stabilisée à température ambiante par substitution de quelques atomes de vanadium par d'autres espèces métalliques. Ces oxydes mixtes sont dénommés par l'acronyme bimevox ou me est le nouveau métal introduit. Des études physico-chimiques (RMN a l'état solide et RPE) et des tests catalytiques effectues sur ces solides ont permis de mieux cerner leur structure tant à l'état précurseur oxyde qu'après réduction. Bi4v2o11 à l'état oxyde présente quatre environnements différents pour le vanadium + 5 et une faible quantité de v4+. A l'état réduit, cet oxyde binaire a une structure fortement dépendante de la nature du réducteur utilise et du temps de réduction. L'activité de bi4v2o11 envers l'isopropanol est plutôt de type déshydratante. Pour ce qui concerne les bimevox, la structure avant réduction dépend de la concentration du métal ajoute. Une relation directe entre la valeur de déplacement chimique du signal rmn#5#1v et les différentes phases structurales des bimevox a été établie. Sous atmosphère d'hydrogène, la phase , très conductrice, permet aux oxygènes du réseau de migrer très rapidement et de supprimer, au fur et à mesure de leur apparition, les lacunes anioniques de surface. La résultante de ce phénomène est une faible activité hydrogenante de ces oxydes mixtes.
APA, Harvard, Vancouver, ISO, and other styles
5

Ballot, Noémie. "Matériaux nanométriques à base de métaux 3d (Fe, Co, Ni) : Nouvelles voies de synthèse et caractérisations." Thesis, Paris 13, 2014. http://www.theses.fr/2014PA132065/document.

Full text
Abstract:
L’intérêt grandissant envers les nanomatériaux a base des métaux de transition 3d comme le cobalt, le nickel et le fer trouve son origine dans les propriétés intrinsèques de ces éléments (forte aimantation du fer et constante magnétocristalline élevée du cobalt) combinées aux propriétés particulières offertes par la taille nanométrique et l’anisotropie de ces alliages. Parmi les nombreuses voies de synthèse dites de chimie douce, le procède polyol permet l’élaboration de plusieurs classes de matériaux inorganiques a l’état finement divises (oxydes, hydroxydes et métaux) grâce aux réactions de réduction et d’hydrolyse qui peuvent être conduites et contrôlées dans les milieux polyols. Le premier axe de ce travail a consisté à tirer profit de l’état finement divise des oxydes et hydroxydes élabores en milieu polyol pour l’obtention de métaux et alliages correspondants, au moyen d’une réduction ménagée a l’état solide sous flux d’hydrogène. Il a alors été possible d’aboutir a des particules de CoFe2, CoFe, NiFe, Ni3Fe et Fe ferromagnétiques avec une température de blocage supérieure a 300 K. Le deuxième axe de travail a trait a l’élaboration d’objets anisotropes. Pour ce faire, une nouvelle approche est proposée : la synthèse en milieu polyol assistée par l’application d’un champ magnétique. Ce type de synthèse mené a des nanofils d’akaganeite β-FeOOH et a des nanoparticules d’oxydes spinelles. Une réduction relativement douce (300 °C) des nanofils d’akaganeite permet de l’obtention de phases spinelles de même morphologie et avec des propriétés magnétiques en accord avec la composition chimique et le caractère nanométrique des particules (comportement superparamagnétique avec une température de blocage proche de 300 K, Ms élevée et Hc dépendant de la nature de l’élément M se trouvant dans le spinelle MFe2O4 : élevé dans le cas du cobalt et faible dans le cas du fer et du nickel)
The growing interest in nanomaterials based on 3d transition metals such as cobalt, iron and nickel finds its origin in the intrinsic properties of these elements (high magnetization of iron and high magnetocristalline constant of cobalt) combined with particular property due to nanometric size and anisotropy of these alloys. Among the numerous synthetic routes, the polyol method which belongs to the chimie douce routes allows the elaboration of several finely divided inorganic materials (oxides, hydroxides, metals) by means of reduction or forced hydrolysis reactions conducted in polyol medium. The main first contribution of this work was to take advantage of these finely divided oxides and hydroxides elaborated in polyol medium to obtain metals and alloys, through a controlled reduction in solid form under hydrogen flow. Ferromagnetic particles of CoFe2, CoFe, NiFe, Ni3Fe and Fe with a blocking temperature above 300 K were obtained. The second main contribution of this work relates elaboration of anisotropic objects. Further, a new approach is proposed: forced hydrolysis in polyol medium assisted by applying a magnetic field. This type of synthesis leads to akaganeite β7&eOOH nanowires and spinel oxides nanoparticles. A relative mild reduction (300 °C) of akaganeite nanowires allows to obtain spinels phase with same morphology and magnetic properties in agreement with the chemical composition and the particles nanoscale (superparamagnetic behavior with blocking temperaturenear 300 K, high Ms and Hc dependent on the nature of the M element in the spinel MFe2O4, high in the case of cobalt and low for nickel and iron)
APA, Harvard, Vancouver, ISO, and other styles
6

Duan, Yan. "Understanding the oxygen evolution reaction (OER) for Co based transition metal oxides / hydroxides in alkaline electrolytes." Electronic Thesis or Diss., Sorbonne université, 2021. http://www.theses.fr/2021SORUS416.

Full text
Abstract:
Le développement d'électrocatalyseurs efficaces pour la réaction de libération d'oxygène (OER) est important pour améliorer l'efficacité globale du processus d'électrolyse de l'eau. Les oxydes / hydroxydes de métaux de transition présentent une activité et une stabilité raisonnables lorsqu’utilisés dans un milieu alcalin. Ils ont le potentiel de remplacer les oxydes à base d'Ir et de Ru. Comprendre la réaction d’OER pour les oxydes / hydroxydes de métaux de transition dans les électrolytes alcalins aide à la conception d'électrocatalyseurs peu coûteux et très efficaces. Avec trois travaux différents sur les oxydes / hydroxydes à base de Co, cette thèse approfondit la compréhension des propriétés de surface des matériaux et des propriétés interfaciales sur la cinétique de la réaction d’OER. Tout d'abord, la substitution au fer régule par exemple la configuration des cations métalliques dans LaCoO3. Cela ajuste la covalence de la liaison oxygène 2p – métal 3d et améliore les performances. Deuxièmement, la substitution au Ni dans ZnCo2O4 modifie la position relative du centre de la bande O 2p et du centre de la bande métallique dans un environnement octahédrique MOh. Cela modifie la stabilité et la possibilité pour l'oxygène du réseau de participer à la réaction de dégagement d’oxygène. Enfin, en étudiant les séries La1-xSrxCoO3, CoOOH et CoOOH contenant Fe, l'impact de l'électrolyte sur les paramètres de la cinétique de réaction a été exploré. Avec une meilleure compréhension de la façon dont les propriétés des matériaux et l'environnement dynamique influencent l'activité et le mécanisme des OER, nous pouvons obtenir des catalyseurs de OER plus efficaces pour une meilleure infrastructure énergétique
The development of efficient electrocatalysts to lower the overpotential of oxygen evolution reaction (OER) is of fundamental importance in improving the overall efficiency of fuel production by water electrolysis. Among a plethora of catalysts being studied on, transition metal oxides / hydroxides that exhibit reasonable activity and stability in alkaline electrolyte have been identified as catalysts to potentially overpass the activity of expensive Ir- and Ru- based oxides. Understanding the OER for transition metal oxides / hydroxides in alkaline electrolytes paves the way for better design of low cost and highly efficient electrocatalysts. This dissertation, with three different work on Co-based oxides / hydroxides, studies and deepens the understanding of the bulk properties, surface properties of materials and interfacial properties on OER. Firstly, with Fe substitution, it addresses tuning the eg configuration of metal cations in LaCoO3 where adjusting the metal 3d oxygen 2p covalency can bring benefits to the OER performance. Secondly, with Ni substitution in ZnCo2O4, it demonstrates a change in relative position of O p-band and MOh d-band centre which induces a change in stability as well as the possibility for lattice oxygen to participate in the OER. Finally, with La1-xSrxCoO3 series, CoOOH and Fe-containing CoOOH as examples, the impact of the electrolyte has been explored by the study of reaction kinetics parameters. With a better understanding of how material properties and dynamic environment influence the OER activity and mechanism, we can obtain more efficient OER catalysts for better energy infrastructure
APA, Harvard, Vancouver, ISO, and other styles
7

Lovat, Silvia. "Oxygen transfer catalysis by d0 metal complexes : activation/deactivation by Lewis base co-ligands." Doctoral thesis, Università degli studi di Padova, 2010. http://hdl.handle.net/11577/3427013.

Full text
Abstract:
Oxidative transformation is one of the fundamental reactions occurring in organic chemistry and is the basis of many synthetic processes. This ia an area of an ongoing research work addressed both to the synthetic application and to the understanding of the mechanism involved in these processes, whose interest include reactions occurring in biological system also. In enzymes, as in artificial catalysts, the presence of metals in high oxidation state allow the activation of hydrogen peroxide (H2O2) and alkyl hydroperoxides (RO2H) and the subsequent oxidation of different organic substrates. Both in enzymes and in artificial systems the sourranding environment of the peroxidic reactive species is of great importance. The ligands bounded to a metal center, such as proteins or molecules from synthesis, are able to increase not only the stability and reactivity, but also the stereoselectivity of the metal. However, there are numerous examples in the literature of how the reactivity, stability and stereoselectivity of cataytic synthetic processes catalyzed by polidentate catalysts may be largely influenced by the presence of additives or monodentate ligands able to bind to the metal center. The influence that polidentate ligands or monodentate ligands may exsert on the reactivity of several catalytic systems is part of the topics covered in the first chapter of this thesis. In particular, we have addressed our attention to catalytic oxidative processes which are accelerated after the bind of ligands both poly- and monodentate. Numerous examples from recent literature have been reported. They are divided into two classes of phenomena: the "ligand accelerated catalysis (LAC) and the co-ligand accelerated catalysis (LAC-CO ). In LAC, as defined by Sharpless, the addition of a polydentate chiral ligand induces the genaration, towards ligand exchange, of a new chiral metallic complex characterized by an increased reactivity. In CO-LAC, the addition of a chiral or achiral monodentate ligand allows the modification of the reactivity of the original metal complex without the occurrency of a ligand exchange. In Chapter 2 we have focused our attention on the reactivity of a polyhedral oligomeric silsesquioxane trisilanolate vanadium(V) complex towards oxidation reactions. This catalyst, at room temeperature and in the presence of cumyl hydroperoxide as the terminal oxidant is efficient in oxygen transfer processes towards sulfides, tertiary amine and secondary amine. Sulfoxidations and N-oxidations have been carried out yielding the corrisponding products in good yields. The addition of a Lewis base as a co-ligand can markedly affect reactivity, stability, chemo- and stereo-selectivity. A proposal for the intermolecular activation, using Gutmann analysis supported by MP2/TZVP calculations, has been presented. In Chapter 3 catalytic sulfoxidations, using cumylhydroperoxide as primary oxidant, has been tested in a series of eight aminotriphenolate d0 metals complexes [Sc(III), Ti(IV), Zr(IV), Hf(IV), V(V), Nb(V), Ta(V), Mo(VI)]. The reactivity and selectivity properties ,both in presence and in absence of a strong Lewis Base (dimethylhexyl-N-oxide) as co-ligand, has been determined experimentally. The experimental values have been correlated with the Sanderson value of electronegativity. MP2/LANL2DZ theoretical calculations on model complexes have furnished more insights on the characteristics of the reactive peroxo specie. The experimentals combined with the theoretical calculations have offered the possibility to propose a general mechanism for the peroxide activation and reactivity. The study described in Chapter 4 pertains to V(V)-oxo amine triphenolate complexes as functional and structural model of vanadium haloperoxidases: their trigonal bypiramidal geometry emulates the one found in the enzymes and their ability to catalyse efficiently sulfoxidations as well as chlorination and bromination of trimethoxybenzene reflects the properties of the enzyme. In particular, sulfoxidations using hydrogen peroxide as terminal oxidant are performaed in quantitative yields and high selectivities ( catalyst loading down to 0.01%, TONs up to 9900, TOF up to 8000 h-1), while in the second case TONs up to 1260 and TOF up to 220 h-1 are achieved with a acatlyst loading down to 0.05%. In Chapter 5 some synthtic method for the preparation of a new fluorinated incompletely condensed polyhedral oligomeric silsesquioxane suitable to be immobilized on polymeric fluorous membranes or in addition able to be dissolved in fluorous solvents have been reported.
La trasformazione ossidativa di gruppi funzionali costituisce una delle reazioni fondamentali della chimica organica ed è alla base di moltissimi processi sintetici. Si tratta di un settore che è oggetto di un continuo lavoro di ricerca, indirizzato sia alla risoluzione di problemi sintetico-applicativi che alla comprensione dei meccanismi che operano in tali processi il cui interesse è così vasto da includere reazioni che avvengono anche in sistemi biologici. Negli enzimi, così come nei catalizzatori artificiali, la presenza di metalli in elevato stato di ossidazione permette l'attivazione di acqua ossigenata (H2O2) e di idroperossidi alchilici (RO2H) consentendo l’ossidazione di diversi substrati organici. Sia negli enzimi che nei sistemi artificiali particolare importanza riveste l’intorno chimico della specie reattiva metalloperossidica responsabile del trasferimento di ossigeno. I leganti al centro metallico, siano essi di natura proteica o costituiti da molecole di sintesi, sono in grado di aumentare non solo la stabilità e la reattività ma anche la capacità di stereoselezione del centro reattivo. Tuttavia, si trovano in letteratura numerosi esempi di come la reattività, la stabilità e la stereoselezione di processi sintetici catalizzati da complessi con leganti polidentati vengano ampiamente influenzati anche dalla presenza di additivi, o leganti monodentati per lo più basici, in seguito alla loro interazione con il metallo. L’influenza che leganti polidentati e co-leganti monodentati possono avere sulla reattività di numerosi sistemi catalitici è parte degli argomenti trattati nel primo capitolo di questa tesi di dottorato. In particolare abbiamo voluto indirizzare la nostra attenzione verso processi reattivi, soprattutto di tipo ossidativo, che vengono accelerati in seguito all’azione sia di leganti polidentati che di co-leganti monodentati. I numerosi esempi che sono stati riportati su questo argomento, tratti dalla recente letteratura, sono stati suddivisi all’interno di due classi di fenomeni: la “ligand accelerated catalysis” (LAC) e la “co-ligand accelerated catalysis” (CO-LAC). Nella LAC, secondo la definizione di Sharpless, l’aggiunta di un legante chirale polidentato induce la formazione, tramite scambio di legante, di un nuovo complesso metallico dotato di una aumentata reattività che spesso si accompagna anche ad una aumentata stereoselettività. Nella CO-LAC invece, l’aggiunta di un legante monodentato chirale o achirale, induce una modificazione della reattività del complesso metallico senza che vi sia scambio di legante. Numerosi esempi di CO-LAC prevedono l’utilizzo di leganti monodentati basici. Durante questo dottorato, abbiamo potuto constatare che il processo di trasferimento di ossigeno verso il metil p-tolil solfuro catalizzato da un complesso polisilosanico di V(V) recanti sostituenti iso-butilici in presenza di CHP come ossidante primario viene accelerato, anche di 24 volte, a seguito dell’aggiunta di basi di Lewis in quantità confrontabili con quelle del catalizzatore. Nel Capitolo 2 i dati sperimentali riportati evidenziano l’esistenza di una corrispondenza tra accelerazione osservata del processo e natura elettron donatrice della base di Lewis usata. Più elettron ricca è la base di Lewis maggiore è la reattività del sistema e, probabilmente a causa delle migliori capacità coordinanti del co-legante, minore è la quantità di base di Lewis necessaria per avere l’effetto massimo. Calcoli computazionali condotti hanno dimostrato come la coordinazione di basi di Lewis al vanadio inducano variazioni di distribuzione elettronica con aumento di densità elettronica all’ossigeno della specie reattiva metalloperossidica coinvolto nel trasferimento di ossigeno e contemporanea diminuzione della stessa a livello del centro metallico con conseguente stabilizzazione dell’intermedio reattivo. Lo studio sugli effetti delle basi di Lewis in processi di trasferimento di ossigeno a solfuri organici è stato esteso anche verso un’altra classe di leganti ossia le trifenolammine. Nel Capitolo 3 sono stati investigati processi catalitici di ossidazione del metil p-tolil solfuro per mezzo di cumilidroperossido come ossidante primario in presenza di otto complessi ammino tri-fenolati di metalli d0 [Sc(III), Ti(IV), Zr(IV), Hf(IV), V(V), Nb(V), Ta(V), Mo(VI)]. La reattività e la selettività di questi processi, sia in assenza che in presenza di una base di Lewis forte come il dimetilesil-N-ossido è stata determinata sperimentalmente. I dati sperimentali ottenuti sono stati correlati con i valori di elettronegatività di Sanderson e tramite studi teorici sono state tratte delle delucidazioni sulle caratteristiche della specie reattiva metalloperossidica. I dati sperimentali raccolti e i calcoli teorici ci hanno permesso di proporre un meccanismo generale per spiegare l’attivazione della specie perossidica e la sua reattività. Nel Capitolo 4 sono descritti i complessi ammino tri-fenolati di ossovanadio(V) come modelli funzionali e strutturali di aloperossidasi, grazie alla loro geometria trigonale bipiramidale e alla loro abilità nel catalizzare efficacemente sia le solfossidazioni così come la bromurazione e la clorurazione del trimetossibenzene. In particolare, nell’ossidazione di solfuri, usando perossido d’idrogeno come ossidante primario, sono state ottenute con rese quantitative in prodotto con alta chemoselettività, anche in presenza dello 0.01% di catalizzatore, con TON fino a 9900 e TOF fino a 8000 h-1. Nel caso della bromurazione si sono ottenuti TON pari a 1260 e TOF fino a 220 h-1 usando fino allo 0.05% di catalizzatore. Nel Capitolo 5 viene riportata una serie di strategie di sintesi per la formazione di un nuovo legante trisilanolico polisilossanico recante lunghe catene perfluorurate come sostituenti.
APA, Harvard, Vancouver, ISO, and other styles
8

Filimonenkov, Ivan. "Electrocatalyse de la réduction de l’oxygène et de l’oxydation de l’eau par des oxydes de métaux de transition : cas des pérovskites de Mn et Co." Thesis, Strasbourg, 2019. http://www.theses.fr/2019STRAF072.

Full text
Abstract:
L’étude de l'électrocatalyse des réactions de réduction de l'oxygène (RRO) et de dégagement de l'oxygène (RDO) est étroitement reliée au développement de matériaux cathodiques et anodiques pour les piles à combustible et les électrolyseurs. L’objectif de cette thèse est de développer et d’étudier des matériaux d’électrodes à base d’oxydes de Mn et de Co, actifs et stables, à la fois pour la RRO et la RDO. Les relations entre les caractéristiques électrochimiques des compositions pérovskite / carbone et les propriétés de leurs composants sont établies et étayées expérimentalement dans la thèse. Il a été constaté que la résistance des matériaux carbonés à la corrosion dans les conditions de la RDO est influencée non seulement par leur ordre cristallin, mais également par leur activité intrinsèque pour la RDO. Il a été démontré que les activités des pérovskites à base de Mn et de Co dépendent linéairement du nombre de cations de Mn et de Co rechargeables, respectivement pour la RRO et la RDO. Il a été découvert qu'une intercalation réversible de l'oxygène dans la structure cristalline des pérovskites à base de Co se produit dans les conditions de la RDO, ainsi qu'à des potentiels plus faibles
A study of electrocatalysis of oxygen reduction (ORR) and oxygen evolution (OER) reactions is closely related with a development of cathodic and anodic materials for fuel cells and elec-trolyzers. An objective of this thesis is to develop and investigate Mn, Co-oxide-based elec-trode materials active and stable in both the ORR and OER. Relationships between electro-chemical characteristics of perovskite/carbon compositions and properties of their compo-nents are stated and experimentally substantiated in the thesis. It is found a corrosion re-sistance of carbon materials under OER conditions is influenced not only by their crystalline order, but also by their intrinsic OER activity. It is shown the ORR and OER activity of Mn, Co-based perovskites linearly depends on the number of rechargeable Mn and Co cations, respectively. It is revealed a reversible oxygen intercalation through a crystal structure of Co-based perovskites occurs under OER conditions as well as at lower potentials
APA, Harvard, Vancouver, ISO, and other styles
9

Grandvallet, Pierre. "Synthèse d'alcools supérieurs à partir de (CO + H) : préparation et caractérisation de catalyseurs oxydes mixtes à base de cuivre et cobalt : étude de l'état stationnaire et du mécanisme réactionnel /." Paris : Technip, 1986. http://catalogue.bnf.fr/ark:/12148/cb34880063v.

Full text
APA, Harvard, Vancouver, ISO, and other styles
10

Arab-Chapelet, Bénédicte. "Étude fondamentale des mécanismes réactionnels intervenant lors de la synthèse par co-conversion oxalique de composés oxyde à base d'actinides." Lille 1, 2005. http://www.theses.fr/2005LIL10147.

Full text
Abstract:
En fin de traitement du combustible nucléaire usé, la co-conversion par co-précipitation oxalique est une des voies envisagées pour immobiliser les actinides à l'état solide pour leur recyclage ultérieur. Le développement de ce procédé repose sur la connaissance précise des structures oxalate co-précipitées. La résolution structurale par diffraction des rayons X sur monocristal d'oxalates U(IV)-Ln(III), où les lanthanides simulent le comportement des actinides, débouche sur la mise en évidence d'un site cristallographique mixte U(IV)-Ln(III) inédit et l'établissement d'une base de données structurales décisive pour l'identification des solides susceptibles de se former lors de la co-précipitation oxalique d'actinides. Par ailleurs, la caractérisation fine de ces oxalates mixtes (i) confirme l'existence de solutions solides et précise leurs domaines d'existence ; (ii) traduit le transfert quantitatif des actinides de la solution au solide précipité sans modification de leur(s) degré(s) d'oxydation ; (iii) explicite le rôle des cations monochargés participant à la compensation des charges au sein de la structure. Finalement, ces résultats singuliers ont été étendus aux mélanges An(IV)-An(III) avec la synthèse d' oxalates mixtes de structures analogues à celles déterminées pour les co-précipités U(IV)-Ln(III). L'existence d'un site cristallographique mixte An(N)-An(III) au sein d'un composé oxalate, à la base des propriétés originales du co-précipité, est pour la première fois décrite. En découle la répartition homogène des différents cations métalliques dans ces oxalates, précurseurs de choix pour l'élaboration d'oxydes mixtes de composition et de microstructure maîtrisées
At the end of the nuclear fuel reprocessing, co-conversion by oxalic co-precipitation is one of the routes investigated to immobilize actinides in a solid compound before their subsequent recycling. The development of this process requires a good knowledge of the structure of the co-precipitated compounds. The structural resolution by single crystal X-ray diffraction of U(IV)-Ln(III) oxalates, where lanthanides simulate the actinides behaviour, led to elucidate three solid solutions characterized by an unexpected U(IV)-Ln(III) mixed site and to the constitution of a structural database decisive for the identification of actinides co-precipitated compounds. In addition, the thorough investigation of these mixed oxalates has allowed (i) to specify the solid solution domains; (ii) to underline the quantitative transfer of actinides initially in solution to the co-precipitated solid, without modification of their oxidation state; (iii) to clarify the role of monovalent cations taking part in the deficit charge compensation in the structure. Finally, these original results were extended to the An(IV)-An(III) mixtures and mixed oxalates exhibiting structures similar to those obtained for the U(IV)-Ln(III) co-precipitates, were synthesised. The existence of An(IV)-An(III) mixed site within a compound oxalate is totally original and at the basis of the original properties of the co-precipitate. Then, actinides co-precipitation allows to elaborate particularly homogeneous solid compounds with desired composition which can be advantageously used as starting materials for mixed oxides synthesis
APA, Harvard, Vancouver, ISO, and other styles
More sources

Books on the topic "Oxydes à base de Co"

1

Aspen, Harald. Competition and co-operation: North Ethiopian peasant households and their resource base. Trondheim: UNIT Centre for Environment and Development, 1993.

Find full text
APA, Harvard, Vancouver, ISO, and other styles
2

Ramesh, B. R. Biotik: Biodiversity informatics and co-operation in taxonomy for interactive shared knowledge base. Pondicherry: Institut français de Pondichéry, 2010.

Find full text
APA, Harvard, Vancouver, ISO, and other styles
3

Varley, Rita. The government household transfer data base, 1960-1984. Paris, France: OECD, Dept. of Economics and Statistics, 1986.

Find full text
APA, Harvard, Vancouver, ISO, and other styles
4

Varley, Rita. The government household transfer data base, 1960-1984. [Paris]: Organisation for Economic Co-operation and Development, 1986.

Find full text
APA, Harvard, Vancouver, ISO, and other styles
5

Statistics, Organisation for Economic Co-operation and Development Dept of Economics and. An international sectoral data base for thirteen OECD countries. Paris: OECD, 1988.

Find full text
APA, Harvard, Vancouver, ISO, and other styles
6

Leung, Emi. Mechanistic Investigation of Novel Niobium-Based Materials as Enhanced Oxygen Storage Components and Innovative CO Oxidation Catalyst Support for Environmental Emission Control Systems. [New York, N.Y.?]: [publisher not identified], 2016.

Find full text
APA, Harvard, Vancouver, ISO, and other styles
7

M, Wheeler R., and United States. National Aeronautics and Space Administration., eds. A data base of nutrient use, water use, CO₂ exchange, and ethylene production by soybeans in a controlled environment. [Washington, D.C: National Aeronautics and Space Administration, 1998.

Find full text
APA, Harvard, Vancouver, ISO, and other styles
8

United States. National Aeronautics and Space Administration., ed. 10,000-hour cyclic oxidation behavior at 982 C (1800 F) of 68 high-temperature Co, Fe-, and Ni-base alloys. [Washington, D.C: National Aeronautics and Space Administration, 1997.

Find full text
APA, Harvard, Vancouver, ISO, and other styles
9

United States. National Aeronautics and Space Administration., ed. 10,000-hour cyclic oxidation behavior at 982 C (1800 F) of 68 high-temperature Co, Fe-, and Ni-base alloys. [Washington, D.C: National Aeronautics and Space Administration, 1997.

Find full text
APA, Harvard, Vancouver, ISO, and other styles
10

United States. National Aeronautics and Space Administration., ed. 10,000-hour cyclic oxidation behavior at 982 C (1800 F) of 68 high-temperature Co, Fe-, and Ni-base alloys. [Washington, D.C: National Aeronautics and Space Administration, 1997.

Find full text
APA, Harvard, Vancouver, ISO, and other styles
More sources

Book chapters on the topic "Oxydes à base de Co"

1

Robinson, Tim, David White, and Ross Grassi. "Acid Mist Abatement in Base Metal Electrowinning." In Ni-Co 2013, 143–53. Cham: Springer International Publishing, 2013. http://dx.doi.org/10.1007/978-3-319-48147-0_9.

Full text
APA, Harvard, Vancouver, ISO, and other styles
2

Robinson, Tim, David White, and Ross Grassi. "Acid Mist Abatement in Base Metal Electrowinning." In Ni-Co 2013, 141–53. Hoboken, NJ, USA: John Wiley & Sons, Inc., 2013. http://dx.doi.org/10.1002/9781118658826.ch9.

Full text
APA, Harvard, Vancouver, ISO, and other styles
3

Eherer, Stefan, and Matthias Jarke. "Knowledge Base Support for Hypermedia Co-Authoring." In Database and Expert Systems Applications, 465–70. Vienna: Springer Vienna, 1991. http://dx.doi.org/10.1007/978-3-7091-7555-2_78.

Full text
APA, Harvard, Vancouver, ISO, and other styles
4

Wilson, Douglas Clyde. "Fisheries Co-Management and the Knowledge Base for Management Decisions." In The Fisheries Co-management Experience, 265–79. Dordrecht: Springer Netherlands, 2003. http://dx.doi.org/10.1007/978-94-017-3323-6_16.

Full text
APA, Harvard, Vancouver, ISO, and other styles
5

Kerr, Carolyn L. "Perioperative Fluid, Electrolyte, and Acid-Base Disorders." In Canine and Feline Anesthesia and Co-Existing Disease, 129–50. Hoboken, NJ, USA: John Wiley & Sons, Inc., 2014. http://dx.doi.org/10.1002/9781118834305.ch7.

Full text
APA, Harvard, Vancouver, ISO, and other styles
6

Chatterjee, M., A. Pani Kishore, P. Sarkar, and M. Narayana Rao. "Effect of Processing Conditions on Structure, Properties and Performance of a Nickel Base Cast Superalloy for High Temperature Applications." In Ni-Co 2013, 357–63. Cham: Springer International Publishing, 2013. http://dx.doi.org/10.1007/978-3-319-48147-0_28.

Full text
APA, Harvard, Vancouver, ISO, and other styles
7

Chatterjee, M., A. Pani Kishore, P. Sarkar, and M. Narayana Rao. "Effect of Processing Conditions on Structure, Properties and Performance of a Nickel Base Cast Superalloy for High Temperature Applications." In Ni-Co 2013, 357–63. Hoboken, NJ, USA: John Wiley & Sons, Inc., 2013. http://dx.doi.org/10.1002/9781118658826.ch28.

Full text
APA, Harvard, Vancouver, ISO, and other styles
8

Black, Jonathan. "In vivo Corrosion of a Cobalt-Base Alloy and Its Biological Consequences." In Biocompatibility of Co-Cr-Ni Alloys, 83–100. Boston, MA: Springer US, 1988. http://dx.doi.org/10.1007/978-1-4613-0757-0_8.

Full text
APA, Harvard, Vancouver, ISO, and other styles
9

Volz, N., C. H. Zenk, T. Halvaci, K. Matuszewska, S. Neumeier, and M. Göken. "Castability and Recrystallization Behavior of γ′-Strengthened Co-Base Superalloys." In Superalloys 2020, 901–8. Cham: Springer International Publishing, 2020. http://dx.doi.org/10.1007/978-3-030-51834-9_88.

Full text
APA, Harvard, Vancouver, ISO, and other styles
10

Hammerschmidt, T., J. Koßmann, C. H. Zenk, S. Neumeier, M. Göken, I. Lopez-Galilea, L. Mujica Roncery, et al. "The Role of Local Chemical Composition for TCP Phase Precipitation in Ni-Base and Co-Base Superalloys." In Superalloys 2016, 89–96. Hoboken, NJ, USA: John Wiley & Sons, Inc., 2016. http://dx.doi.org/10.1002/9781119075646.ch10.

Full text
APA, Harvard, Vancouver, ISO, and other styles

Conference papers on the topic "Oxydes à base de Co"

1

Mingotaud, N., A. Bertoli, and P. Fauchais. "Thick Coatings(>1.5 mm) of CoNiCrAlY Sprayed by HVOF." In ITSC 1996, edited by C. C. Berndt. ASM International, 1996. http://dx.doi.org/10.31399/asm.cp.itsc1996p0457.

Full text
Abstract:
Abstract Spherical CoNiCrAlY powders (~45 + 5 μm) were sprayed using a Jet Kote II HVOF gun working with propane and oxygen. The coatings sprayed on two base materials: Inconel 625 (Ni base) and MarM 509 (Co base) were between 1,6 and 3 mm thick. The aim of the study was to examine the adherence problems in relation with this thickness and the imposed thermal cycles (thermal diffusion treatment and aluminizing). The studied parameters were the expansion coefficients evolution before and after the different treatments and the residual stresses between coating and substrate measured by incremental hole dilling method.
APA, Harvard, Vancouver, ISO, and other styles
2

Monaghan, Rory F. D., and Monem H. Alyaser. "Integrated Oxygen-Free Gasification-Gas Turbine Power Concept: A Low-Emissions Alternative for Small-Scale Coal Plants." In ASME 2011 5th International Conference on Energy Sustainability. ASMEDC, 2011. http://dx.doi.org/10.1115/es2011-54123.

Full text
Abstract:
A power plant concept with the potential to replace the large fleet of ageing, small-scale (< 50 MWe), inefficient, polluting, and soon-to-be obsolete coal-fired power plants is proposed. The proposed plant comprises a bituminous coal-fed oxygen-free gasifier, low-temperature syngas cleanup system and an open-cycle gas turbine with heat recovery. Heat is supplied to the gasifier through combustion of a portion of the cleaned syngas produced by it. Since the proposed plant employs only a gas turbine, with no steam bottoming cycle, heat recovery from the gas turbine and its integration with the rest of the plant is crucial. A thermodynamic model of the plant has been created to assess its feasibility based on overall efficiency and emissions of CO2, SO2, mercury and particulates. The model comprises submodels for feedstock composition and enthalpy, as well as first-order thermodynamic models for each of the plant components including the gasifier, feedstock preparation, heat exchangers and steam generators, contaminant removal, combustors and turbomachinery. The results of the analysis show base case plant thermal efficiency of 38.2% on a HHV basis, which is roughly 5% points higher than that for a similarly-sized pulverized coal combustion (PCC) plants. Emissions of CO2, SO2, mercury and particulates per unit electrical energy produced in the base case are: 0.774 kg/kWh, 47.2 g/MWh, 2.37 g/GWh and 28.2 g/MWh, respectively. These values are well below emissions from similarly-sized PCC plants, which have been assessed using a spreadsheet model. The model of the proposed plant has been used to assess overall performance when torrefied pine wood is co-gasified with coal. Results show a slight decrease in plant efficiency with increasing co-gasification, with large decreases in CO2, SO2 and mercury emissions. Emissions of particulates increase slightly with co-gasification. Finally the model has been used to perform sensitivity analysis on the proposed system. Sensitivity analysis highlights the need for greater understanding of gasifier performance under a range of conditions.
APA, Harvard, Vancouver, ISO, and other styles
3

Guilemany, J. M., J. Sánchez, and J. M. de Paco. "Spray Gun Influence on the Oxidation of TiC+Ni-Ti Based Powders During HVOF Spraying." In ITSC 1999, edited by E. Lugscheider and P. A. Kammer. Verlag für Schweißen und verwandte Verfahren DVS-Verlag GmbH, 1999. http://dx.doi.org/10.31399/asm.cp.itsc1999p0446.

Full text
Abstract:
Abstract TiC-based coatings have proven to be very suitable candidates in various areas of thermal spraying when high corrosion and wear resistance is required. The most important advantages of these coatings are their high corrosion resistance compared to conventional coatings such as WC+Co and WC+Co+Cr, but also their low density. However, the main problem with HVOF spraying these materials is their high reactivity with the oxygen necessary for the flame. In this paper, Self-Propagating High-Temperature Synthesis-TiC+Ni-Ti base powder are processed with two different spray guns (Diamond Jet Hybrid (DJH) and CDS 100). This allows to compare the properties of the resultant coatings (wear and corrosion mainly) as a consequence of the main advantages of each variable (gun and gas) particularly in relation to the oxidation processes. It is observed that DJH coatings showed the best corrosion resistance whilst CDS coatings showed a corrosion potential closer to the steel value. Paper includes a German-language abstract.
APA, Harvard, Vancouver, ISO, and other styles
4

AFOLABI, Akindele Segun, Chikara OHTA, and Hisashi TAMAKI. "A Base Station Co-operation Protocol for Indoor Base Stations." In Annual International Conference on Advances in Distributed and Parallel Computing ADPC 2010. Global Science and Technology Forum, 2010. http://dx.doi.org/10.5176/978-981-08-7656-2_ntc2010-30.

Full text
APA, Harvard, Vancouver, ISO, and other styles
5

Cao, Xiaochun, Yupeng Cheng, Zhiqiang Tao, and Huazhu Fu. "Co-Saliency Detection via Base Reconstruction." In MM '14: 2014 ACM Multimedia Conference. New York, NY, USA: ACM, 2014. http://dx.doi.org/10.1145/2647868.2655007.

Full text
APA, Harvard, Vancouver, ISO, and other styles
6

Verstak, A., and G. Kusinski. "High Velocity Air-Fuel Spraying and Its Applications in Oil and Gas Industry." In ITSC 2012, edited by R. S. Lima, A. Agarwal, M. M. Hyland, Y. C. Lau, C. J. Li, A. McDonald, and F. L. Toma. ASM International, 2012. http://dx.doi.org/10.31399/asm.cp.itsc2012p0529.

Full text
Abstract:
Abstract Recent developments of High-Velocity Air-Fuel (HVAF) spraying and blasting focused on a substantial increase of spray particles velocity. The efforts further improved coating quality, allowing deposition of metallic and carbide-base coatings non-permeable to gas at thickness as low as 40-50 micron. The coatings demonstrate low dissolved oxygen content, a favorable combination of high hardness and toughness. Coupled with the enhanced technological efficiency of modern HVAF equipment, this initiated not only the acceptance of HVAF technologies in established thermal spray markets in the oil and gas industry, but also the development and successful implementation of new coating applications. The examples are wear and corrosion resistant tungsten carbide-based coatings on hydraulics rods of dock cranes, corrosion resistant Ni-Cr-Mo-type coatings on vessels of sulfur removal equipment, tungsten carbide coatings on restriction grid plates and slide gates of catalyst towers, high-temperature erosion resistant chromium carbide- based coatings on thermowells and valve stems, wear and cavitation resistant Co-Cr-W-C-type and carbide coatings on housing wear rings and impeller hubs of high-temperature pumps.
APA, Harvard, Vancouver, ISO, and other styles
7

Liao, W. B., and Y. Zhang. "Processing and properties of Cu-base and Co-base amorphous wires." In High Density Packaging (ICEPT-HDP). IEEE, 2009. http://dx.doi.org/10.1109/icept.2009.5270553.

Full text
APA, Harvard, Vancouver, ISO, and other styles
8

Jerković, Sanja, and Nives Škreblin. "BASE EARTHQUAKE." In 1st Croatian Conference on Earthquake Engineering. University of Zagreb Faculty of Civil Engineering, 2021. http://dx.doi.org/10.5592/co/1crocee.2021.277.

Full text
APA, Harvard, Vancouver, ISO, and other styles
9

Mizuno, H., I. Aoki, S. Tawada, H. Ibe, K. Sato, and J. Kitamura. "Cavitation Erosion for WC Cermet Coating Prepared by HVOF." In ITSC2008, edited by B. R. Marple, M. M. Hyland, Y. C. Lau, C. J. Li, R. S. Lima, and G. Montavon. Verlag für Schweißen und verwandte Verfahren DVS-Verlag GmbH, 2008. http://dx.doi.org/10.31399/asm.cp.itsc2008p0037.

Full text
Abstract:
Abstract Cavitation erosion is one of the serious problems that affect lifetime and performance on hydraulic machineries and its components. Surface modification techniques is required to apply to hydraulic components, such as water turbine and radial flow pump, in general. Here, the techniques, which can easily be applied to large area, is must be required for actual applications in the fields. Thus, thermal sprayed WC cermet coatings with high abrasion resistance under wet conditions are one of the promising solutions as the protective coatings against cavitation erosion. In this study, WC/Cr3C2/Ni and WC/Co/Cr coatings prepared using a high-velocity oxygen fuel (HVOF) spraying have been evaluated by a magneto-striction vibratory apparatus to investigate the cavitation erosion resistance. The microstructures of the sprayed coatings after the cavitation erosion test have been analyzed by SEM to clarify the erosion mechanism. It has been found that the cavitation erosion resistance of the WC cermet coatings is significantly affected by primary particle size of WC, powder compositions and spray conditions. In the WC/10wt%Co/4wt%Cr, the coating with WC average particle size of 6.3 µm sprayed by optimized spray conditions achieved the highest cavitation erosion resistance than the other WC coatings as well as base materials of stainless steel used in the actual components.
APA, Harvard, Vancouver, ISO, and other styles
10

Scrivani, A., M. Soranzo, G. Rizzi, U. Bardi, and L. Carafiello. "On the Stripping of Turbine Blades and Vanes: Mechanisms and Performances of Chemical Stripping for the Removal of NiCrAlY Thermal Spray Coatings." In ITSC2003, edited by Basil R. Marple and Christian Moreau. ASM International, 2003. http://dx.doi.org/10.31399/asm.cp.itsc2003p0745.

Full text
Abstract:
Abstract The present paper is addressed to the study of chemical stripping processes used in order to remove Thermal Spray deposited Thermal Barrier Coatings. Thermal Barrier Coatings consist in a bond coat of MCrAlY alloy (where M means for Ni, Co or a combination of both), that can be obtained generally by Vacuum Plasma Spray or High Velocity Oxygen Fuel and in a top coat of Yttria Partially Stabilized Zirconia obtained by Air Plasma Spray. These coatings are applied to gas turbine components in order to improve their hot corrosion and oxidation resistance and their service life time through a reduction of the service temperature. The paper focuses on the removal of NiCrAlY bond coat performed by chemical attack (based on hydrochloric acid). Characterization of the blade and vane surfaces after removal of NiCrAlY coatings has been performed from the point of view of surface morphology, metallurgical structure and chemical composition. The efficiency of the acid solution in NiCrAlY removal has been investigated and the behaviour of two Ni based alloys substrates in aggressive environment has been tested. The HCl based stripping solution shows good performances in Vacuum Plasma Sprayed NiCrAlY coatings removal from Ni superalloys. The tested stripping procedure is fast and safe because no damages to base materials have been noted.
APA, Harvard, Vancouver, ISO, and other styles

Reports on the topic "Oxydes à base de Co"

1

Kelly, Sean, Joan Geary, Shrikar Chakravrti, Jamie Wilson, Max Christie, John Peck, Juan Li, et al. Recovery. Oxygen Transport Membrane-Based OxyCombustion for CO2 Capture from Power Plants. Office of Scientific and Technical Information (OSTI), December 2015. http://dx.doi.org/10.2172/1243056.

Full text
APA, Harvard, Vancouver, ISO, and other styles
2

ME Petrichek. Experimental Design for Evaluation of Co-extruded Refractory Metal/Nickel Base Superalloy Joints. Office of Scientific and Technical Information (OSTI), December 2005. http://dx.doi.org/10.2172/884672.

Full text
APA, Harvard, Vancouver, ISO, and other styles
3

Corriveau, L. Les systèmes minéralisateurs à oxydes de fer et altération à éléments alcalins (±calciques) et leurs gîtes IOA, IOCG, skarns, U±Au±Co (au sein d'albitites) et affiliés: une série de cours intensifs. Partie 1 : introduction. Natural Resources Canada/ESS/Scientific and Technical Publishing Services, 2017. http://dx.doi.org/10.4095/300242.

Full text
APA, Harvard, Vancouver, ISO, and other styles
4

Mallon, B., D. Layton, R. Fish, P. Hsieh, L. Hall, L. Perry, and G. Snyder. Conventional weapons demilitarization: A health and environmental effects data base assessment: Propellants and their co-contaminants. Office of Scientific and Technical Information (OSTI), August 1988. http://dx.doi.org/10.2172/5873712.

Full text
APA, Harvard, Vancouver, ISO, and other styles
5

Young, Allison, Carey Baxter, Joseph Murphey, Karlee Feinen, Madison Story, and Adam Smith. US Air Force Academy Gallagher and Massey ranch houses : Historic American Buildings Surveys CO-237, CO-237-A, and CO-238. Engineer Research and Development Center (U.S.), June 2023. http://dx.doi.org/10.21079/11681/47190.

Full text
Abstract:
The US Congress codified the National Historic Preservation Act of 1966 (NHPA), the nation’s most effective cultural resources legislation to date, mostly through establishing the National Register of Historic Places (NRHP). The NHPA requires federal agencies to address their cultural resources, which are defined as any prehistoric or historic district, site, building, structure, or object. Section 110 of the NHPA requires federal agencies to inventory and evaluate their cultural resources, and Section 106 requires them to determine the effect of federal undertakings on those potentially eligible for the NRHP. The US Air Force Academy is located at the base of the Front Range within El Paso County. The US Air Force Academy has been used for training US Air Force officers since 1954. The Gallagher Ranch House and its associated garage, erected circa 1953, and the Massey Ranch House, erected 1941, are eligible for the National Register of Historic Places. This report documents the buildings to the standards of the Historic American Buildings Survey and includes a historic context, architectural descriptions, photographs, and measured drawings. This report satisfies Sections 106 and 110 of the National Historic Preservation Act of 1966 as amended and will be used by the US Air Force Academy for mitigation, allowing for the demolition of the three buildings.
APA, Harvard, Vancouver, ISO, and other styles
6

Tomova, Zlatina, Angelina Vlahova, Christo Kissov, Rada Kazakova, and Dimitar D. Radev. Corrosion Resistance and Biocompatibility of Multicomponent Ni- and Co ‑ Base Dental Alloys Obtained by Methods of Powder Metallurgy. "Prof. Marin Drinov" Publishing House of Bulgarian Academy of Sciences, July 2018. http://dx.doi.org/10.7546/crabs.2018.07.05.

Full text
APA, Harvard, Vancouver, ISO, and other styles
7

Corriveau, L., E. G. Potter, J. F. Montreuil, O. Blein, K. Ehrig, and A. F. De Toni. Les systèmes minéralisateurs à oxydes de fer et altération à éléments alcalins (±calciques), et leurs gîtes IOA, IOCG, skarns, U±Au±Co (au sein d'albitites) et affiliés : une série de cours intensifs. Partie 2 : Aperçu général des types de gîtes, distribution, âges, contextes, exemples, faciès d'altération et modèles métallogéniques. Natural Resources Canada/ESS/Scientific and Technical Publishing Services, 2018. http://dx.doi.org/10.4095/308269.

Full text
APA, Harvard, Vancouver, ISO, and other styles
8

Chepeliev, Maksym. Development of the Air Pollution Database for the GTAP 10A Data Base. GTAP Research Memoranda, June 2020. http://dx.doi.org/10.21642/gtap.rm33.

Full text
Abstract:
The purpose of this note is to document data sources and steps used to develop the air pollution database for the GTAP Data Base Version 10A. Emissions for nine substances are reported in the database: black carbon (BC), carbon monoxide (CO), ammonia (NH3), non-methane volatile organic compounds (NMVOC), nitrogen oxides (NOx), organic carbon (OC), particulate matter 10 (PM10), particulate matter 2.5 (PM2.5) and sulfur dioxide (SO2). The dataset covers four reference years – 2004, 2007, 2011 and 2014. EDGAR Version 5.0 database is used as the main data source. To assist with emissions redistribution across consumption-based sources, IIASA GAINS-based model and IPCC-derived emission factors are applied. Each emission flow is associated with one of the four sets of emission drivers: output by industries, endowment by industries, input use by industries and household consumption. In addition, emissions from land use activities (biomass burning) are estimated by land cover types. These emissions are reported separately without association with emission drivers.
APA, Harvard, Vancouver, ISO, and other styles
9

Kudin, Roman, Prabhat Chand, and Anura Bakmeedeniya. Mitigating Nitrogen Oxides Exhaust Emissions from Petrol Vehicles by Application of a Fuel Additive. Unitec ePress, August 2020. http://dx.doi.org/10.34074/rsrp.083.

Full text
Abstract:
This research has been commissioned by Eco Fuel Global Limited, a New Zealand-based company, to further evaluate the effects of their fuel-additive product on the tailpipe exhaust emissions of petrol cars. At the time this research was conducted (end of 2018), the product was still in development and had not been released to the market. Prior to the testing in this research, an initial pilot test was done for the same product on a single car (Nissan Pulsar 1998), which showed favourable results, with a reduction in hydrocarbons and oxides of nitrogen at the tailpipe by more than 70%. The current research included five test cars, all running on RON 95 fuel, with the years of manufacture ranging between 1994 and 2006, and the odometer readings between 112,004 km and 264,001 km. The effects of the fuel-additive product were assessed by comparing the emissions from a car running on standard fuel with the emissions from the same car after it completed a road run (250±20 km) on the additive-treated fuel. The exhaust emissions were measured using the AVL series 4000 Emission Tester, which analyses five components: carbon monoxide (CO), carbon dioxide (CO2), oxides of nitrogen (NOX), hydrocarbons (HC) and oxygen (O2). The most noticeable outcome of using the fuel-additive product was the reduction in the concentration of oxides of nitrogen in the tailpipe exhaust (by up to 27.7%), when compared with the same cars running on standard fuel. In addition, the results showed a decrease in residual oxygen concentration, which normally indicates more complete utilisation of O2 as an oxidising agent. Mitigating Nitrogen Oxides Exhaust Emissions from Petrol Vehicles by Application of a Fuel Additive Dr Roman Kudin, Prabhat Chand and Anura Bakmeedeniya 2 The changes for other emission parameters were either relatively small (below 1%) or were not statistically significant. The application of such fuel-additive products could be beneficial for mitigating nitrogen oxides exhaust emissions from petrol vehicles in countries with ageing car fleets. These include New Zealand, which has a relatively high proportion of old cars in use, with no government-run scrappage scheme, and without a mandatory objective emissions testing.
APA, Harvard, Vancouver, ISO, and other styles
10

Page, Kelly, Alexandra Merritt Johnson, Kristen Franklin, Bria Carter, Marilys Galindo, Teresa Solorzano, Sangyeon Lee, and Zohal Shah. Principios de Aprendizaje de la Transición de Diseño para los Expedientes de Aprendizaje y Empleo: Co-diseño para la Equidad. Digital Promise, July 2023. http://dx.doi.org/10.51388/20.500.12265/186.

Full text
Abstract:
Las tecnologías emergentes, como los registros de aprendizaje y empleo (LER), se han identificado como una solución prometedora para que los alumnos y trabajadores histórica y sistemáticamente excluidos (HSE) compartan y accedan a sus datos de aprendizaje y competencias a partir de sus itinerarios de aprendizaje y transiciones individuales. Sin embargo, los itinerarios de aprendizaje rara vez son lineales; la forma en que los alumnos y los trabajadores pueden demostrar y obtener reconocimiento por sus habilidades y competencias puede evolucionar con el tiempo. Además, las barreras sistémicas y las desigualdades arraigadas en los itinerarios de aprendizaje de las comunidades de HSE afectan de manera desproporcionada a su capacidad para acceder y persistir en el ecosistema educativo y laboral. Es fundamental que los LER se diseñen de forma accesible y equitativa para las comunidades de HSE a fin de mitigar las desigualdades sistémicas y estructurales en el ecosistema educativo y laboral. Con el generoso apoyo de la Fundación Bill y Melinda Gates, Digital Promise colaboró con alumnos adultos y trabajadores de la ESS para establecer un conjunto de principios de diseño que sirvieran de base para el desarrollo de tecnologías de REA para su uso a lo largo de la trayectoria profesional y de aprendizaje de las personas, incluidas sus transiciones de aprendizaje. Mediante entrevistas individuales y talleres de grupo con alumnos adultos y trabajadores de la HSE, se han identificado los principios de diseño clave para influir en la infraestructura de datos LER desde la educación hasta la fuerza laboral.
APA, Harvard, Vancouver, ISO, and other styles
You might also be interested in the extended bibliographies on the topic 'Oxydes à base de Co' for particular source types:
Journal articles Dissertations / Theses Books
We offer discounts on all premium plans for authors whose works are included in thematic literature selections. Contact us to get a unique promo code!

To the bibliography