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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
291

Chert Nastapoka : caractérisation chimique et exploitation au Paléoesquimau, baie d’Hudson, Nunavik

Leclerc, Marianne-Marilou 04 1900 (has links)
Les assemblages lithiques dominent la plupart des sites archéologiques du Nunavik et constituent ainsi une véritable mine d’informations. Le nombre limité de travaux sur les matériaux de la côte est de la baie d’Hudson, nous a amené à nous pencher sur une source présente dans ce secteur. Notre objectif était alors de caractériser la matière première provenant de cette formation géologique, le chert Nastapoka. Pour ce faire, nous avons choisi la technique de fluorescence aux rayons X. Les résultats ont permis de constater, en plus des observations macroscopiques, la nature très variable de ce chert présentant une signature chimique complexe. Pour compléter le portrait, nous avons évalué l’utilisation du chert Nastapoka par les Paléoesquimaux par une comparaison d’analyses technologiques déjà effectuées sur les sites GhGk-4, GhGk-63 et IcGm-5. Cet examen a révélé que l’évolution des stratégies d’exploitation des matériaux lithiques dans cette région appui le continuum culturel Prédorsétien-Dorsétien observé ailleurs. / The dominant cultural material on Nunavik’s archaeological sites is lithics. As a result they constitute an important source of information on prehistoric lifeways. The lack of lithic raw materials resarchs carried out on the east coast of Hudson Bay gave us the opportunity to focus on a source in this area. The objective of this thesis research was to characterize one component of the geological formation: Nastapoka chert. In order to do this, X-ray fluorescence was chosen. The results demonstrate that it is difficult to construct a unique geochemical pattern for the source because of its variability. To complete the portrait, we take into account the technological use of Nastapoka chert by the Paleoeskimo groups by comparing three site’s studies (GhGk-4, GhGk-63 and IcGm-5). This analysis of the exploitation of this material reveals a developement from Predorset to Dorset that supports the idea of cultural continuum between the two periods.
292

Chert Nastapoka : caractérisation chimique et exploitation au Paléoesquimau, baie d’Hudson, Nunavik

Leclerc, Marianne-Marilou 04 1900 (has links)
Les assemblages lithiques dominent la plupart des sites archéologiques du Nunavik et constituent ainsi une véritable mine d’informations. Le nombre limité de travaux sur les matériaux de la côte est de la baie d’Hudson, nous a amené à nous pencher sur une source présente dans ce secteur. Notre objectif était alors de caractériser la matière première provenant de cette formation géologique, le chert Nastapoka. Pour ce faire, nous avons choisi la technique de fluorescence aux rayons X. Les résultats ont permis de constater, en plus des observations macroscopiques, la nature très variable de ce chert présentant une signature chimique complexe. Pour compléter le portrait, nous avons évalué l’utilisation du chert Nastapoka par les Paléoesquimaux par une comparaison d’analyses technologiques déjà effectuées sur les sites GhGk-4, GhGk-63 et IcGm-5. Cet examen a révélé que l’évolution des stratégies d’exploitation des matériaux lithiques dans cette région appui le continuum culturel Prédorsétien-Dorsétien observé ailleurs. / The dominant cultural material on Nunavik’s archaeological sites is lithics. As a result they constitute an important source of information on prehistoric lifeways. The lack of lithic raw materials resarchs carried out on the east coast of Hudson Bay gave us the opportunity to focus on a source in this area. The objective of this thesis research was to characterize one component of the geological formation: Nastapoka chert. In order to do this, X-ray fluorescence was chosen. The results demonstrate that it is difficult to construct a unique geochemical pattern for the source because of its variability. To complete the portrait, we take into account the technological use of Nastapoka chert by the Paleoeskimo groups by comparing three site’s studies (GhGk-4, GhGk-63 and IcGm-5). This analysis of the exploitation of this material reveals a developement from Predorset to Dorset that supports the idea of cultural continuum between the two periods.
293

La production et la diffusion des céramiques utilitaires de style à bandes à Argilos et dans le nord de l'Égée aux périodes archaïque et classique.

Perron, Martin 04 1900 (has links)
Cette étude porte sur l’analyse des céramiques de style à bandes – mieux connues dans la littérature anglo-saxonne sous le nom de waveline pottery – produites dans le nord de l’Égée aux périodes archaïque et classique. Cette catégorie de récipients, dont les formes et l’ornementation s’inspirent principalement des productions issues des ateliers micrasiatiques des VIIe et VIe siècles av. J.-C., jouit d’une vaste distribution en Thrace et en Macédoine orientale. Elle regroupe une importante variété de vaisselles d’usage courant utilisées pour le service et le stockage des denrées. Cette recherche propose de dresser le portrait de la production et de la diffusion de ces céramiques en Égée du Nord par le biais de l’étude de céramiques recueillis sur sept colonies grecques établies entre le Strymon et le golfe de Maronée et six sites de l’arrière-pays thrace. Elle vise à rassembler, au moyen de données archéologiques et archéométriques, des informations sur les milieux de production, les réseaux d’échanges et les habitudes de consommation de la clientèle à l’égard de ces céramiques. Le volet archéologique vise d’abord à définir le répertoire des formes, des décors et des pâtes argileuses, puis à déterminer l’étendue et le cadre chronologique de la production. Le volet archéométrique porte sur des analyses physico-chimiques en laboratoire (spectrométrie de fluorescence par rayons X) visant à caractériser et à déterminer l’origine de 200 des 540 céramiques recensées. Le corpus est principalement constitué d’échantillons mis au jour sur les sites d’Argilos, de Thasos, de Bergè et de Phagrès, en Macédoine orientale. L’inédit de la recherche réside dans l’opportunité qu’elle offre aux archéologues de dater et d’identifier l’origine des céramiques à bandes, entraînant des répercussions directes sur les discussions portant sur les milieux de production, les réseaux de circulation, les relations interrégionales et les habitudes de consommation à l’égard de ces céramiques. dans le nord de l’Égée entre les VIIe et IVe siècles av. J.-C. / This research aims to shed light on the production and diffusion of the Waveline pottery made in the Northern Aegean during the Archaic and Classical periods. It is based on the study of unpublished finds recovered from seven Greek colonies established between the Strymon River and the Gulf of Maronea, and six sites of the Thracian hinterland. More specifically, it seeks to gather information regarding workshops, trading networks, and consumption habits through typo-stylistical, distribution, and archaeometric analyses. The primary goal of this study is the detailed analysis of the finds according to their stratigraphic contexts in order to define the range of shapes, stylistic patterns, and clay fabrics of the ceramic series, and to establish diffusion patterns and chronology. A second objective, based on laboratory analysis, is to characterize the geochemical composition of 200 of the 540 identified vessels in order to determine their provenance (using X-ray fluorescence spectrometry). The corpus contains samples from Argilos, Thasos, Berge, and Phagres, four of the main sites covered by this study. The novelty of this research lies in the opportunity it provides for archaeologists to date and identify more precisely the origin of the North-Aegean waveline pottery, leading to direct impact on discussions related to workshops, trading networks, and inter-relationships between the studied sites. Considered from the perspective of circulation and exchange, the study of the Waveline pottery contributes to advancing knowledge on the economic, cultural, and social history of the Northern Aegean between the 7th and 4th centuries B.C. / Thèse doctorale effectuée en cotutelle au département d'histoire de l'Université de Montréal et à l'École doctorale d'archéologie de l'Université Paris 1 Panthéon-Sorbonne - UMR 7041, Archéologies et Sciences de l'Antiquité - Archéologie du monde grec.
294

La production et la diffusion des céramiques utilitaires de style à bandes à Argilos et dans le nord de l'Égée aux périodes archaïque et classique

Perron, Martin 04 1900 (has links)
No description available.
295

Desenvolvimento de novos eletrocatalisadores para celulas a combustivel a membrana polimerica trocadora de protons

FRANCO, EGBERTO G. 09 October 2014 (has links)
Made available in DSpace on 2014-10-09T12:49:30Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T14:02:27Z (GMT). No. of bitstreams: 1 10381.pdf: 10221895 bytes, checksum: 882d02701e24d30dd8869849c8502249 (MD5) / Tese (Doutoramento) / IPEN/T / Intituto de Pesquisas Energeticas e Nucleares, IPEN/CNEN-SP
296

Terras raras: fracionamento, purificação e controle analítico

QUEIROZ, CARLOS A. da S. 09 October 2014 (has links)
Made available in DSpace on 2014-10-09T12:54:09Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T14:09:15Z (GMT). No. of bitstreams: 1 12442.pdf: 17943869 bytes, checksum: d8ae26da3e514d980c366a9cafa81e22 (MD5) / Dissertacao (Mestrado) / IEA/D / Instituto de Quimica, Universidade de Sao Paulo - IQ/USP
297

Comparação da difusão de fósforo em solos brasileiros para diferentes fertilizantes granulados usando fluorescência de raios X por reflexão total por radiação síncroton (SR-TXRF) / Phosphorus diffusion of comparison in brazilians soils for different granular fertilizer using total reflection X-ray fluorescence by synchrotron radiation (SRTXRF).

Robson Costa de Castro 30 June 2015 (has links)
O fósforo (P) é um nutriente essencial para o crescimento das plantas. Milhões de toneladas de P são aplicados aos solos anualmente. No entanto, apenas uma pequena fração do P aplicado com fertilizantes é aproveitada nas lavouras no ano de aplicação, bem como a eficácia do fertilizante fosfatado diminui com o tempo. Para melhorar a nossa compreensão dos mecanismos, a esta resposta do P no campo, este trabalho visa estudar a migração desse elemento em solos tropicais brasileiros (Latossolo vermelho e Latossolo amarelo) tratados com três tipos de fertilizantes: fosfato monoamônico (MAP), o polímero revestido de fosfato monoamônio (MAPP) e fosfato organomineral (OMP) em um experimento de placa de Petri. Fluorescência de Raios X por Reflexão Total (TXRF) foi usada para determinar o fluxo difusivo P a distâncias radiais diferentes (entre 0 e 7,5 mm, entre 7,5 e 13,5 mm, 13,5 e 25,5 mm e entre 25,5 e 43 mm) a partir do grânulo de fertilizante. As análises usando TXRF foram realizadas no Laboratório Nacional de Luz Síncrotron (LNLS), em Campinas, São Paulo, na linha de Fluorescência de Raios X (Beamline D09B). Depois de um período de cinco semanas, a concentração total de P, Ca e Al foram obtidas e comparadas analisando o tipo de solo/textura, o pH e o respectivo extrator de P, que nesse estudo foram usados o Mehlich 1 e água régia. De forma geral, concluiu-se que 80,0 % de fósforo proveniente dos fertilizantes usados nessa proposta ficaram concentrados em distâncias menores que 10 mm do ponto de aplicação dos fertilizantes, independentemente do tipo de solo, do pH e da respectiva textura. Em relação à utilização da técnica TXRF, o sistema foi eficiente, dentre outras características, na discriminação dos picos de fósforo dos picos de enxofre, principalmente nas amostras de solo usadas a partir da extração com Mehlich 1. Destaca-se isso, pois os raios X característicos desses elementos são muitos próximos. / Phosphorus is an essential nutrient for plant growth. Million of tones of P are applied to the soils annually. However, only a small fraction of the P applied with fertilizers is taken up by crops in the year of application, and the effectiveness of any residual P fertilizer declines with time. To improve our understanding of the mechanisms underlying this response to P in the field, this work aims to study the migration of this element in Brazilian tropical soils (red and yellow Oxisol) treated with three types of fertilizers: monoammonium phosphate (MAP), polymer coated monoammonium phosphate (MAPp) and Organomineral phosphate (OMP) in a Petri dish experiment. Total Reflection X-Ray Fluorescence (TXRF) was used to determine the P diffusive flux at different distances (0 - 7.5, 7.5 13.5, 13.5 25.5 and 25.5 43 mm) from granular fertilizer. TXRF analyses were performed at the X-Ray Fluorescence Beamline D09B at Brazilian National Synchrotron Light Laboratory (LNLS), in Campinas, São Paulo. After a period of five weeks, the total concentration of P, Ca and Al were obtained and compared by analyzing the type/soil texture, pH, and the respective extractor P, this study used the Mehlich 1 and aqua regia . In general, it was found that 80.0 % of phosphorus from the fertilizer used in this proposal were concentrated in distances smaller than 10 mm from the point of application of fertilizers , regardless of the soil type , pH, and its texture. Regarding the use of TXRF technique , the system was efficient , among other features , the breakdown of phosphorus peaks of the sulfur peaks , especially in the soil samples used from the extraction with Mehlich 1. It is noteworthy that, as the rays X characteristic of these elements are very close.
298

Desenvolvimento de novos eletrocatalisadores para celulas a combustivel a membrana polimerica trocadora de protons

FRANCO, EGBERTO G. 09 October 2014 (has links)
Made available in DSpace on 2014-10-09T12:49:30Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T14:02:27Z (GMT). No. of bitstreams: 1 10381.pdf: 10221895 bytes, checksum: 882d02701e24d30dd8869849c8502249 (MD5) / Tese (Doutoramento) / IPEN/T / Intituto de Pesquisas Energeticas e Nucleares, IPEN/CNEN-SP
299

Terras raras: fracionamento, purificação e controle analítico

QUEIROZ, CARLOS A. da S. 09 October 2014 (has links)
Made available in DSpace on 2014-10-09T12:54:09Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T14:09:15Z (GMT). No. of bitstreams: 1 12442.pdf: 17943869 bytes, checksum: d8ae26da3e514d980c366a9cafa81e22 (MD5) / Dissertacao (Mestrado) / IEA/D / Instituto de Quimica, Universidade de Sao Paulo - IQ/USP
300

Analyses of Common Elements and Oxides in the Paleosols of the Bahamas and of the Northern Mariana Islands

Ersek, Vasile 07 August 2004 (has links)
Paleosols from the Bahamas and the Northern Mariana Islands (CNMI) are closely related to past atmospheric circulation and dust load. In the Bahamas the sources of insoluble residue (IR) must be allogenic because the islands consist of almost pure carbonates. The Al2O3:TiO2 ratio was used to establish the provenance of the IR of the paleosols. Comparisons of this ratio from Bahamian paleosols, North African dust, Lesser Antilles ash and North American loess reveal that the African dust is the major contributor to the IR, with a potential minor volcanic input from the Lesser Antilles. The contribution of the North American loess to the IR was not determined because of geochemical similarities with the North African dust. The study of two outcrops in Eleuthera indicate that paleosols can act as aquicludes. The Bahamian samples were collected on a roughly north-south transect in order to establish the climatic influence on paleosol properties. Even though there is a marked climatic gradient in the Bahamas, the paleosol geochemistry shows no trend that could be related to paleoclimate. While previous studies indicated that the source of insoluble residues in the soils of CNMI is carbonate dissolution, the present study shows that atmospheric deposition of ash from the Mariana arc and dust from the Asian continent may play a significant role in paleosol formation.

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