Submitted by Marco Antonio Oliveira da Silva (maosilva@ipen.br) on 2016-12-22T12:40:27Z No. of bitstreams: 0 / Made available in DSpace on 2016-12-22T12:40:27Z (GMT). No. of bitstreams: 0 / Foram estudados as propriedades de absorção ótica, de termoluminescência e de ressonância paramagnética eletrônica do mineral natural de silicato de nome MONTICELITA do grupo Olivina, para caracterização desse mineral, cuja formula química é CaMgSiO4. A absorção ótica mostrou que há três bandas de absorção em 450 nm, 660 nm e 1050 nm. As duas primeiras bandas, a primeira no azul e a segunda no amarelo-vermelho são responsáveis pela cor verde da Monticelita. Essas duas bandas são consequência do elemento cromo contido no mineral absorver fótons do feixe universal no visível de frequências centradas em 450 nm e 660 nm. A banda em 1050 nm é devido ao Fe2+. As curvas de emissão de uma amostra de Monticelita irradiada com raios gama de doses entre 10 e 1000 Gy apresenta três picos em 150 °C , 270 °C e 370 °C . Pelo método da deconvolução e de várias taxas de aquecimento foram obtidos energia E1=1,35 eV e fator de frequência s1=4,98x1011 s-1 para o pico 270 °C e E2=1,70 eV e s2=1,88x1011 s-1 para pico 370 °C . A irradiação com raios gama de doses entre 5 kGy e 50 kGy produziram pico TL de 380 °C com intensidade TL em função da dose linear e crescente. Este resultado e importante para dosimetria da radiação de altas doses. O espectro EPR de uma amostra natural, mostrou um resultado não esperado e interessante. Além dos sinais típicos de interação hiperfina do Mn2+, um sinal avantajado de g =6,34 indica que o ferro formou moléculas de hematita, Fe2O3. Esse sinal desaparece com aquecimento acima de 800 °C de recozimento, dando origem dipolos magnéticos de Fe3+, que dá origem a um sinal típico em g =2. Esta descrição mostra bem a caracterização do mineral Monticelita. / Dissertação (Mestrado em Tecnologia Nuclear) / IPEN/D / Instituto de Pesquisas Energéticas e Nucleares - IPEN-CNEN/SP

Submitted by Pedro Silva Filho (pfsilva@ipen.br) on 2017-11-17T16:39:31Z No. of bitstreams: 0 / Made available in DSpace on 2017-11-17T16:39:31Z (GMT). No. of bitstreams: 0 / A radiação ionizante é amplamente utilizada em diversas áreas na indústria e na medicina. No campo da medicina, a radiação ionizante é utilizada tanto para fins terapêuticos como para fins diagnósticos, abrangendo assim um grande intervalo de doses de diferentes tipos de radiações. Para certificar que a finalidade da prática esteja sendo alcançada, são necessários estudos detalhados de detectores e dispositivos que atendam aos diferentes tipos de radiações. Neste trabalho foi realizado um estudo das características dosimétricas de amostras de BeO em feixes padronizados de radiodiagnóstico convencional, mamografia e tomografia computadorizada, utilizando as técnicas de termoluminescência (TL) e luminescência opticamente estimulada (OSL) e propondo um sistema adequado para sua utilização em dosimetria de feixes. Os principais resultados obtidos foram: alta sensibilidade à luz branca durante a irradiação, boa reprodutibilidade das respostas TL e OSL (coeficientes de variação inferiores a 5%), parâmetros cinéticos correspondentes aos valores obtidos em todos os métodos testados, sem fading dentro do período estudado para ambas as técnicas. As características dosimétricas obtidas neste trabalho mostram a possibilidade de aplicação das amostras de BeO em dosimetria da radiação X, considerando os intervalos de dose empregados, pelas técnicas de TL e OSL. Assim, as amostras de BeO apresentaram sua utilização potencial para dosimetria de feixes de radiodiagnóstico convencional, mamografia e tomografia computadorizada. / Dissertação (Mestrado em Tecnologia Nuclear) / IPEN/D / Instituto de Pesquisas Energéticas e Nucleares - IPEN-CNEN/SP

No description available.

Vidros teluritos são considerados fortes candidatos para aplicações em lasers e óptica não linear devido a importantes características, como o elevado índice de refração, baixa energia de fônons, baixa temperatura de transição vítrea e sua fácil preparação. Neste trabalho foram produzidas amostras dos sistemas vítreos TeO2- ZnO-Na2O, TeO2-Nb2O5-Na2O e Te2O-Na2O incluindo ou não dopagens de AgNO3 para estudos estruturais e ópticos. As propriedades estruturais e os mecanismos de recombinação destes vidros foram estudados por meio das técnicas de ressonância paramagnética eletrônica, termoluminescência e correntes de despolarização termicamente estimuladas. Já as propriedades ópticas como o coeficiente de absorção linear, índice de refração linear e não linear foram estudadas por meio das técnicas de absorção óptica, acoplamento de prismas e varredura Z. Foram ainda desenvolvidos estudos da precipitação de nanopartículas de prata para o sistema TeO2-ZnO-Na2O com dopagens de AgNO3 com diferentes temperaturas de tratamento térmico. A caracterização das nanopartículas metálicas foi realizada por meio da técnica de absorção óptica auxiliada por microscopia eletrônica de transmissão e espectrometria de energia dispersiva. Foram observadas por ressonância paramagnética eletrônica quatro respostas paramagnéticas dos vidros irradiados com raio , sendo uma de natureza desconhecida e as outras três identificadas como g¹, g² e g³ atribuídas respectivamente ao centro de buraco do telúrio e do oxigênio, centro de buraco do oxigênio terminal e centro de elétron do telúrio. Foi proposto ainda um modelo para explicar os mecanismos de formação destes centros. A partir dos resultados de termoluminescência observou-se que os processos de recombinação destes centros de defeitos são não radioativos. Neste projeto foram estudados pela primeira vez na literatura os fenômenos de polarização e despolarização em vidros teluritos, com e sem irradiação gama, por meio da técnica de correntes de despolarização termicamente estimuladas. Quanto às propriedades ópticas, foi investigada a influência da adição de prata dos sistemas vítreos TeO2-ZnO-Na2O e TeO2-Nb2O5-Na2O em relação à energia do gap, a cauda de Urbach, índice de refração linear e não linear.Nos resultados de varredura Z do sistema vítreo TeO2-Nb2O5-Na2O foi observado o aumento da assimetria na curva com aumento da adição de AgNO3 Este fenômeno foi explicado por meio de uma adaptação do modelo de Sumi para processos não radiativos, responsáveis pelo aumento do caráter térmico do índice de refração não linear. Por fim um modelo foi criado para explicar a precipitação de nanopartículas de prata na matriz vítrea TeO2-ZnO-Na2O mediante tratamento térmico. / Tellurite glasses are considered powerful candidates for applications in lasers and nonlinear optics due to their important properties such as high refractive index, low phonon energy, relatively low glass transition temperature and easy glass production at room atmosphere. In this work glass samples of the systems ZnO-Na2O, TeO2-Nb2O5-Na2O and Te2O-Na2O were produced, including or not the AgNO3 doping for the structural and optical study purposes. The structural properties and the recombination mechanisms of these glasses were studied by means of the techniques of electron paramagnetic resonance, thermoluminescence and thermally stimulated depolarization currents. The optical properties such as the optical linear absorption coefficient, linear and nonlinear refractive index were studied by means of the optical absorption techniques, prism coupling and Z-scan. Further studies were developed on the precipitation of silver nanoparticles embedded in the glass system TeO2-ZnO-Na2O doped with AgNO3, by means of thermal treatments at different temperatures. The characterization of the metallic nanoparticles was carried out by optical absorption aided by transmission electron microscopy and dispersive energy spectroscopy. Four paramagnetic responses were observed by electron paramagnetic resonance of the -irradiated glasses, one not yet identified and the other three identified as g0, g1 and g3 attributed respectively to the tellurium-oxygen hole center, non-bridging oxygen hole center and tellurium electron center. A model to explain the formation mechanisms of these centers was proposed. The thermoluminescence results indicated that the recombination processes of these centers are non-radiative. This is the first study that deals with polarization and depolarization phenomena in tellurite glasses with and without gamma irradiation, by the technique of thermally stimulated depolarization currents. In what regards the optical properties of the glass systems TeO2-ZnONa2O and TeO2-Nb2O5-Na2O, the effect of the silver doping on the gap energy, Urbach tail, linear and nonlinear refractive indices were investigated. Through the Z-scan technique results of the glass system TeO2-Nb2O5-Na2O, an increasing asymmetry of the curve, with increasing AgNO3 content was observed. This phenomenon was explained through an adaptation of Sumi´s model for non-radiative processes, applied to a silver doped insulating glass, to explain the thermal character of the nonlinear refractive index. Finally, a model was developed to explain the silver nanoparticles precipitation in the TeO2-ZnO-Na2O glass matrix submitted to thermal treatment.

Saltwater Forest is a Dacrydium cupressinum-dominated lowland forest covering 9000 ha in south Westland, South Island, New Zealand. Four thousand hectares is managed for sustainable production of indigenous timber. The aim of this study was to provide an integrated analysis of soils, soil-landform relationships, and soil-vegetation relationships at broad and detailed scales. The broad scale understandings provide a framework in which existing or future studies can be placed and the detailed studies elucidate sources of soil and forest variability. Glacial landforms dominate. They include late Pleistocene lateral, terminal and ablation moraines, and outwash aggradation and degradation terraces. Deposits and landforms from six glacial advances have been recognised ranging from latest Last (Otira) Glaciation to Penultimate (Waimea) Glaciation. The absolute ages of landforms were established by analysis of the thickness and soil stratigraphy of loess coverbeds, augmented with radiocarbon dating and phytolith and pollen analysis. In the prevailing high rainfall of Westland soil formation is rapid. The rate of loess accretion in Saltwater Forest (ca. 30 mm ka⁻¹) has been low enough that soil formation and loess accretion took place contemporaneously. Soils formed in this manner are known as upbuilding soils. The significant difference between upbuilding pedogenesis and pedogenesis in a topdown sense into an existing sediment body is that each subsoil increment of an upbuilding soil has experienced processes of all horizons above. In Saltwater Forest subsoils of upbuilding soils are strongly altered because they have experienced the extremely acid environment of the soil surface at some earlier time. Some soil chronosequence studies in Westland have included upbuilding soils formed in loess as the older members of the sequence. Rates and types of processes inferred from these soils should be reviewed because upbuilding is a different pedogenic pathway to topdown pedogenesis. Landform age and morphology were used as a primary stratification for a study of the soil pattern and nature of soil variability in the 4000 ha production area of Saltwater Forest. The age of landforms (> 14 ka) and rapid soil formation mean that soils are uniformly strongly weathered and leached. Soils include Humic Organic Soils, Perch-gley Podzols, Acid Gley Soils, Allophanic Brown Soils, and Orthic or Pan Podzols. The major influence on the nature of soils is site hydrology which is determined by macroscale features of landforms (slope, relief, drainage density), mesoscale effects related to position on landforms, and microscale influences determined by microtopography and individual tree effects. Much of the soil variability arises at microscales so that it is not possible to map areas of uniform soils at practical map scales. The distribution of soil variability across spatial scales, in relation to the intensity of forest management, dictates that it is most appropriate to map soil complexes with boundaries coinciding with landforms. Disturbance of canopy trees is an important agent in forest dynamics. The frequency of forest disturbance in the production area of Saltwater Forest varies in a systematic way among landforms in accord with changes in abundance of different soils. The frequency of forest turnover is highest on landforms with the greatest abundance of extremely poorly-drained Organic Soils. As the abundance of better-drained soils increases the frequency of forest turnover declines. Changes in turnover frequency are reflected in the mean size and density of canopy trees (Dacrydium cupressinum) among landforms. Terrace and ablation moraine landforms with the greatest abundance of extremely poorly-drained soils have on average the smallest trees growing most densely. The steep lateral moraines, characterised by well drained soils, have fewer, larger trees. The changes manifested at the landform scale are an integration of processes operating over much shorter range as a result of short-range soil variability. The systematic changes in forest structure and turnover frequency among landforms and soils have important implications for sustainable forest management.

Saltwater Forest is a Dacrydium cupressinum-dominated lowland forest covering 9000 ha in south Westland, South Island, New Zealand. Four thousand hectares is managed for sustainable production of indigenous timber. The aim of this study was to provide an integrated analysis of soils, soil-landform relationships, and soil-vegetation relationships at broad and detailed scales. The broad scale understandings provide a framework in which existing or future studies can be placed and the detailed studies elucidate sources of soil and forest variability. Glacial landforms dominate. They include late Pleistocene lateral, terminal and ablation moraines, and outwash aggradation and degradation terraces. Deposits and landforms from six glacial advances have been recognised ranging from latest Last (Otira) Glaciation to Penultimate (Waimea) Glaciation. The absolute ages of landforms were established by analysis of the thickness and soil stratigraphy of loess coverbeds, augmented with radiocarbon dating and phytolith and pollen analysis. In the prevailing high rainfall of Westland soil formation is rapid. The rate of loess accretion in Saltwater Forest (ca. 30 mm ka⁻¹) has been low enough that soil formation and loess accretion took place contemporaneously. Soils formed in this manner are known as upbuilding soils. The significant difference between upbuilding pedogenesis and pedogenesis in a topdown sense into an existing sediment body is that each subsoil increment of an upbuilding soil has experienced processes of all horizons above. In Saltwater Forest subsoils of upbuilding soils are strongly altered because they have experienced the extremely acid environment of the soil surface at some earlier time. Some soil chronosequence studies in Westland have included upbuilding soils formed in loess as the older members of the sequence. Rates and types of processes inferred from these soils should be reviewed because upbuilding is a different pedogenic pathway to topdown pedogenesis. Landform age and morphology were used as a primary stratification for a study of the soil pattern and nature of soil variability in the 4000 ha production area of Saltwater Forest. The age of landforms (> 14 ka) and rapid soil formation mean that soils are uniformly strongly weathered and leached. Soils include Humic Organic Soils, Perch-gley Podzols, Acid Gley Soils, Allophanic Brown Soils, and Orthic or Pan Podzols. The major influence on the nature of soils is site hydrology which is determined by macroscale features of landforms (slope, relief, drainage density), mesoscale effects related to position on landforms, and microscale influences determined by microtopography and individual tree effects. Much of the soil variability arises at microscales so that it is not possible to map areas of uniform soils at practical map scales. The distribution of soil variability across spatial scales, in relation to the intensity of forest management, dictates that it is most appropriate to map soil complexes with boundaries coinciding with landforms. Disturbance of canopy trees is an important agent in forest dynamics. The frequency of forest disturbance in the production area of Saltwater Forest varies in a systematic way among landforms in accord with changes in abundance of different soils. The frequency of forest turnover is highest on landforms with the greatest abundance of extremely poorly-drained Organic Soils. As the abundance of better-drained soils increases the frequency of forest turnover declines. Changes in turnover frequency are reflected in the mean size and density of canopy trees (Dacrydium cupressinum) among landforms. Terrace and ablation moraine landforms with the greatest abundance of extremely poorly-drained soils have on average the smallest trees growing most densely. The steep lateral moraines, characterised by well drained soils, have fewer, larger trees. The changes manifested at the landform scale are an integration of processes operating over much shorter range as a result of short-range soil variability. The systematic changes in forest structure and turnover frequency among landforms and soils have important implications for sustainable forest management.

Vidros teluritos são considerados fortes candidatos para aplicações em lasers e óptica não linear devido a importantes características, como o elevado índice de refração, baixa energia de fônons, baixa temperatura de transição vítrea e sua fácil preparação. Neste trabalho foram produzidas amostras dos sistemas vítreos TeO2- ZnO-Na2O, TeO2-Nb2O5-Na2O e Te2O-Na2O incluindo ou não dopagens de AgNO3 para estudos estruturais e ópticos. As propriedades estruturais e os mecanismos de recombinação destes vidros foram estudados por meio das técnicas de ressonância paramagnética eletrônica, termoluminescência e correntes de despolarização termicamente estimuladas. Já as propriedades ópticas como o coeficiente de absorção linear, índice de refração linear e não linear foram estudadas por meio das técnicas de absorção óptica, acoplamento de prismas e varredura Z. Foram ainda desenvolvidos estudos da precipitação de nanopartículas de prata para o sistema TeO2-ZnO-Na2O com dopagens de AgNO3 com diferentes temperaturas de tratamento térmico. A caracterização das nanopartículas metálicas foi realizada por meio da técnica de absorção óptica auxiliada por microscopia eletrônica de transmissão e espectrometria de energia dispersiva. Foram observadas por ressonância paramagnética eletrônica quatro respostas paramagnéticas dos vidros irradiados com raio , sendo uma de natureza desconhecida e as outras três identificadas como g¹, g² e g³ atribuídas respectivamente ao centro de buraco do telúrio e do oxigênio, centro de buraco do oxigênio terminal e centro de elétron do telúrio. Foi proposto ainda um modelo para explicar os mecanismos de formação destes centros. A partir dos resultados de termoluminescência observou-se que os processos de recombinação destes centros de defeitos são não radioativos. Neste projeto foram estudados pela primeira vez na literatura os fenômenos de polarização e despolarização em vidros teluritos, com e sem irradiação gama, por meio da técnica de correntes de despolarização termicamente estimuladas. Quanto às propriedades ópticas, foi investigada a influência da adição de prata dos sistemas vítreos TeO2-ZnO-Na2O e TeO2-Nb2O5-Na2O em relação à energia do gap, a cauda de Urbach, índice de refração linear e não linear.Nos resultados de varredura Z do sistema vítreo TeO2-Nb2O5-Na2O foi observado o aumento da assimetria na curva com aumento da adição de AgNO3 Este fenômeno foi explicado por meio de uma adaptação do modelo de Sumi para processos não radiativos, responsáveis pelo aumento do caráter térmico do índice de refração não linear. Por fim um modelo foi criado para explicar a precipitação de nanopartículas de prata na matriz vítrea TeO2-ZnO-Na2O mediante tratamento térmico. / Tellurite glasses are considered powerful candidates for applications in lasers and nonlinear optics due to their important properties such as high refractive index, low phonon energy, relatively low glass transition temperature and easy glass production at room atmosphere. In this work glass samples of the systems ZnO-Na2O, TeO2-Nb2O5-Na2O and Te2O-Na2O were produced, including or not the AgNO3 doping for the structural and optical study purposes. The structural properties and the recombination mechanisms of these glasses were studied by means of the techniques of electron paramagnetic resonance, thermoluminescence and thermally stimulated depolarization currents. The optical properties such as the optical linear absorption coefficient, linear and nonlinear refractive index were studied by means of the optical absorption techniques, prism coupling and Z-scan. Further studies were developed on the precipitation of silver nanoparticles embedded in the glass system TeO2-ZnO-Na2O doped with AgNO3, by means of thermal treatments at different temperatures. The characterization of the metallic nanoparticles was carried out by optical absorption aided by transmission electron microscopy and dispersive energy spectroscopy. Four paramagnetic responses were observed by electron paramagnetic resonance of the -irradiated glasses, one not yet identified and the other three identified as g0, g1 and g3 attributed respectively to the tellurium-oxygen hole center, non-bridging oxygen hole center and tellurium electron center. A model to explain the formation mechanisms of these centers was proposed. The thermoluminescence results indicated that the recombination processes of these centers are non-radiative. This is the first study that deals with polarization and depolarization phenomena in tellurite glasses with and without gamma irradiation, by the technique of thermally stimulated depolarization currents. In what regards the optical properties of the glass systems TeO2-ZnONa2O and TeO2-Nb2O5-Na2O, the effect of the silver doping on the gap energy, Urbach tail, linear and nonlinear refractive indices were investigated. Through the Z-scan technique results of the glass system TeO2-Nb2O5-Na2O, an increasing asymmetry of the curve, with increasing AgNO3 content was observed. This phenomenon was explained through an adaptation of Sumi´s model for non-radiative processes, applied to a silver doped insulating glass, to explain the thermal character of the nonlinear refractive index. Finally, a model was developed to explain the silver nanoparticles precipitation in the TeO2-ZnO-Na2O glass matrix submitted to thermal treatment.

Das mittlere Baruther Urstromtal und Umgebung zwischen Luckenwalde und Golßen (Brandenburg, Deutschland) ist reich an äolischen Bildungen (DE BOER, 1990). Aus einer Kombination der bekannten Dünentypen (Parabel-, Längs-, Quer- und Kupstendünen) wird eine Reihe von 6 Dünenkomplexen abgeleitet. Sie sind aus einem oder mehreren Dünentypen aufgebaut und haben eine unterschiedliche Genese, Unterschiede im Alter und der Alterssfolge sowie eine bestimmte topographische Lage. Die (oberflächig anstehenden) Talsande/Flug(deck)sande, die Alt- und die Jungdünensande werden von Fein- bis Mittelsanden gebildet. In den jeweiligen Vertikalprofilen ist nach dem Körnungsbild eine Dreiteilung zu erkennen: die "liegenden" (Urstromtalterrassen-)Sande, die Altdünensande und die "hangenden" Jungdünensande. Das Liegende der ältesten Binnendünen ähnelt den Terrassensanden sehr. Daher darf angenommen werden, daß die oberen Urstromtalsande eine starke äolische Komponente besitzen. Altersbestimmungen wurden durch relative Positionierung, Feststellungen zur Art der Bodenbildungen, archäologische Funde, Pollenanalysen sowie Karten- und Literaturstudien vorgenommen, ergänzt durch Radiokarbon- (14C-) und Thermolumineszenzdatierungen. Eine methodische Neuerung ist die automatisierte Bearbeitung der Dünnschliffbilder. Mit dem Quantimet-970-Bildverarbeitungssystem wurde die Einregelung der Längsachsen von Quarzkörnern ermittelt. Die Messungen ergaben, dass die (N)NO-(S)SW-, die ONO-WSW- und die SSO-NNW-Richtungen vorherrschen. Es ist zu vermuten, dass die wichtigsten dünenbildenden Winde im Weichselspätglazial und im Holozän aus den westlichen und südlichen Quadranten wehten, wobei Südwestwinde vorgeherrscht haben dürften. Auf Grund der Forschungsergebnisse werden 12 Phasen der Dünenbildung unterschieden. Sie vermitteln ein Bild der äolischen Prozesse und Landschaftsformen, welches mit Daten aus Niedersachsen und West-Polen größtenteils übereinstimmt. / The Central Baruth Ice-Marginal Valley and surroundings between Luckenwalde and Golßen (Brandenburg, Germany) is rich in aeolian deposits and aeolian landscape forms DE BOER (1990). From a combination of the well-known dune forms (longitudinal, transverse, parabolic and hummocky dunes) a series of 6 dune complexes can be identified. These dune complexes are built by one or several dune types and differ in genesis or building sequence, in age or age sequence as well as in topographic position. The (surficial) valley/aeolian sands, the cover sands and the drift sands are mainly composed of fine- to medium-grained fractions. Based on grain-size analysis three units can be distinguished in the studied vertical profiles: the underlying (valley terrace) sands, the cover sands ("Altdünensande") and the overlying drift sands ("Jungdünensande"). The sands of the substratum of the oldest inland dunes are very similar to these dune sands. Therefore it is accepted that the upper parts of the valley sands contain a strong aeolian component. A modernization is the automated method of long axes orientation measurements on elongated quartz grains in thin sections with the Quantimet-970 Image Analyzer. The results showed that the (N)NE-(S)SW-, the ENE-WSW- and the SSE-NNW-directions dominated. It is to be expected that the most important dune building winds during the Weichselian Late Glacial and during the Holocene were winds from the western and southern quadrants, with southwest winds most likely being the most important. Dating was done by means of relative positioning, palaeosols, archaeological finds, pollen analysis, cartographic and literature research as well as by means of the 14C- and thermoluminescence dating methods. Based on the results of this research 12 dune-forming phases have been distinguished. They give an impression of aeolian processes and landscape forms that are in accordance with dates obtained from dunes in Niedersachsen and west Poland.