The coordination chemistry of antimony(III) and antimony(V) have been investigated to reveal fundamental structural and electronic features. The limited scope of known cationic antimony(V) complexes was greatly expanded, including the first examples of pnictogen(V) trications. The systematic nature of these investigations led to the observation of redox chemistry, determined to be the result of reductive elimination of chlorobenzene and biphenyl from an antimony center. The reactivity of [Ph2Sb(OPyrMe)4][OTf]3 was investigated and it was found that the OPyrMe ligands are sufficiently labile to perform ligand substitution chemistry. However, when exposed to phosphines, ligand-centered reactivity prevails and phosphonium salts of the form [R3P(2-4-methylpyridine)][OTf] which may be useful reagents in the field of medicinal chemistry and drug design. While attempts were made to synthesise antimony(V) tetra- and penta- cations have been unsuccessful, the methodologies reported here will serve as a foundation to future endeavors. / Graduate / 2019-08-31

Made available in DSpace on 2014-10-09T12:34:07Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T14:00:09Z (GMT). No. of bitstreams: 0 / Dissertação (Mestrado) / IPEN/D / Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP

Made available in DSpace on 2014-10-09T12:27:46Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T14:05:03Z (GMT). No. of bitstreams: 0 / Tese (Doutoramento) / IPEN/T / Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP

Made available in DSpace on 2014-10-09T12:34:07Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T14:00:09Z (GMT). No. of bitstreams: 0 / O antimônio é um elemento encontrado em baixas concentrações no meio ambiente. No entanto, a sua determinação tem despertado grande interesse devido ao conhecimento de sua toxicidade e da crescente aplicação na indústria. A determinação de antimônio tem sido um desafio para os pesquisadores uma vez que o elemento é encontrado em baixas concentrações, o que faz de sua análise uma tarefa difícil. Portanto, embora a análise por ativação de nêutrons (NAA) seja um método adequado para a determinação de vários elementos em diferentes tipos de matriz, no caso de Sb, a análise apresenta algumas dificuldades. A principal dificuldade é devido às interferências espectrais. O objetivo desta pesquisa foi validar o método de NAA para a determinação de Sb em amostras ambientais. Para estabelecer condições adequadas para a determinação de Sb, ensaios preliminares foram realizados para posterior análise de materiais de referência certificados (MRC). O procedimento experimental consistiu em irradiar amostras juntamente com padrão sintético de Sb por períodos de 8 ou 16 horas no reator nuclear de pesquisa IEA-R1, seguido de espectrometria de raios gama. A quantificação de Sb foi realizada pela medição dos radioisótopos de 122Sb e 124Sb. Ensaios preliminares indicaram a presença de Sb em papel de filtro Whatman, utilizado no preparo do padrão, porém em teor muito baixo, podendo ser considerado desprezível. No caso do material plástico utilizado como invólucro para a irradiação da amostra, foi verificado que ele deve ser escolhido cuidadosamente, pois dependendo do plástico, este pode conter Sb. A análise da estabilidade da solução padrão diluída de Sb, dentro do período de oito meses, mostrou que não há alteração significativa na concentração deste elemento. Os resultados obtidos nas análises dos materiais de referência certificados indicaram a formação de radioisótopos de 76As e também de 134Cs e 152Eu, podendo interferir na determinação de Sb pela medição de 122Sb, devido à proximidade de energias dos raios gama emitidos. Além disso, a alta atividade do 24Na pode mascarar o pico do 122Sb e dificultar a sua detecção. As análises dos MRC indicaram que a exatidão e a precisão dos resultados de Sb dependem principalmente do tipo e composição da matriz, da sua concentração na amostra, do radioisotopo medido e do tempo de decaimento utilizado para a medição. A avaliação dos componentes que contribuem para a medição da incerteza da concentração de Sb, mostrou que a maior contribuição da incerteza é dada pela estatística de contagem da amostra. Os resultados da avaliação da incerteza indicaram também que o valor da incerteza padrão combinada depende do radioisótopo medido e do tempo de decaimento utilizado para as contagens. Este estudo mostrou que a NAA é um método bastante adequado na determinação de Sb em amostras ambientais, possibilitando a obtenção de resultados com baixos valores de incerteza e por ser uma técnica puramente instrumental, permite a análise de um grande número de amostras. / Dissertação (Mestrado) / IPEN/D / Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP

Made available in DSpace on 2014-10-09T12:27:46Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T14:05:03Z (GMT). No. of bitstreams: 0 / Leishmanioses são um complexo de doenças infecciosas causadas por protozoários intramacrofágicos do gênero Leishmania, fatal se não tratadas adequadamente. Os antimoniais pentavalentes são os medicamentos de primeira escolha para o tratamento, apesar de sua toxicidade e seu mecanismo de ação pouco esclarecido. Uma terapia mais eficaz pode ser conseguida pelo direcionamento de fármacos antileishmania para os locais de infecção. Os lipossomas são vesículas lipídicas que promovem melhora na eficácia e na ação de fármacos na célula alvo. Os lipossomas são capturados preferencialmente pelas células do sistema mononuclear fagocitário (SMF). O objetivo deste estudo foi desenvolver uma formulação de antimoniato de meglumina lipossomal, constituído por fosfatidilserina e estudar sua farmacocinética em animais sadios para esclarecer seu metabolismo e distribuição. As análises quantitativas de antimônio em lipossomas demonstram que Análise por Ativação Neutrônica foi a técnica mais sensível com cerca de 100 % de precisão. Todas as formulações de lipossomas apresentaram um tamanho de diâmetro médio de 150 nm. A determinação da CE50 em macrófagos infectados mostrou que as formulações de antimoniato de meglumina encapsulado em lipossomas foram entre 10 - 63 vezes mais eficazes do que a fármaco livre, indicando maior índice de seletividade. Por microscopia de fluorescência, foi verificada uma maior internalização de lipossomas fluorescentes em macrófagos infectados durante um curto tempo de incubação em comparação com macrófagos não infectados. A biodistribuição do antimoniato de meglumina irradiado encapsulado em lipossomas contendo fosfatidilserina mostrou que a formulação lipossomal promoveu um direcionamento seletivo do antimônio para tecidos do SMF, além do que manteve as doses elevadas nos órgãos por um período prolongado. Em conclusão, estes dados sugerem que o antimoniato de meglumina encapsulado em lipossomas apresentou maior eficácia do que a fármaco não lipossomal contra a infecção por Leishmania. O desenvolvimento de formulações lipossomais pode ser uma nova alternativa para a quimioterapia de doenças infecciosas, especialmente Leishmanioses, já que são usados como sistemas carreadores para entrega sustentada e direcionada de fármacos ao local da infecção. / Tese (Doutoramento) / IPEN/T / Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP

A modified thin lens spectrometer has been used with improved geometry. The focussing properties of the instrument have been investigated for various geometries. Using this instrument the conversion electron spectra of Sn¹¹³ and Sb¹²⁵ have been taken. The intensity of the 256 kev conversion line in Sn¹¹³ spectrum showed that this transition is predominantly M1 in character and therefore the spin and parity of 648-kev level in In¹¹³ should be 1/2¯ or 3/2¯. The low energy part of the conversion spectrum of Sb¹²⁵showed the presence of the K conversion lines of 76 kev and 143 kev transitions, not observed before. The presence of these conversion lines confirmed the existence of a weak beta group feeding a level at 540 kev in the excited state of Te¹²⁵. The energy levels of Cs¹³³ have been studied through the decay of Ba¹³³. Scintillation spectra (using NaI(T1 ) crystal) together with photoelectron, conversion and e-gamma coincidence spectra have been taken. An analysis of the results indicate that the ground state and 81, 161, 383 and 437 kev levels in Cs¹³³ have spins and parities of 7/2⁺, 5/2⁺,5/2⁺,3/2⁺, 1/2⁺ respectively. The multipolarities of the connecting transitions are 383 kev (E2 ), 356 (E2 ) 302 kev (M1 with E2 admixture)} 276 kev (E2 ), 161 kev (probably M1 ) Electron capture from Ba¹³³ is limited almost entirely to the 437 and 383 kev levels in Cs¹³³, The decay energy available for capture to the 437 level is approximately 50 kev. / Science, Faculty of / Physics and Astronomy, Department of / Graduate

Geology, opaque mineralogy, and alteration assemblages of the Sam Goosly copper-silver-antimony deposit are described in detail and a model for ore genesis is proposed. The deposit occurs in an inlier of Cretaceous sedimentary, pyro-clastic, and volcanic rocks. This inlier is intruded by a quartz monzonite stock in the western part of the property and by a gabbro-monzonite complex in the eastern half. Flat lying to shallow dipping Tertiary andesitic to basaltic flows uncomfortably overlie Cretaceous rocks around the flanks of the inlier. Based on careful examination of over 4,875 m of drill core and on limited surface mapping, four stratigraphic subdivisions striking about 015 degrees and dipping about 45 degrees west have been identified. The Clastic Division, composed of a lower polymictic conglomerate and an upper chert pebble conglomerate, is lowermost and is thought to be correlative with the Skeena Group. Sedimentary rocks are overlain by the Pyroclastic Division, a heterogeneous sequence of tuff, breccia, and reworked pyroclastic debris. Tuff, sandstone, and conglomerate of the Sedimentary-Volcanic Division have well defined bedding and overlie pyroclastic rocks. The uppermost unit composed of andesitic and dacitic flows, is the Volcanic Flow Division. Copper-silver-antimony ores at Sam Goosly are contained in the Main Zone and Southern Tail deposits and are associated with tourmaline, andalusite, scorzalite, and corundum (only in the Main Zone). They are epigenetic and cross-cutting relationships are visible both in hand specimen and throughout the deposit as a whole. The ores occur within the Pyroclastic Division and although they are controlled mainly by structure, crude strati graphic controls are also apparent. Other mineralized areas at Sam Goosly are a zone of porphyry copper-molybdenum mineralization in and adjacent to the quartz monzonite stock and a zone of tourmaline breccia. Similarities in mineralogy, textures, and paragenesis among all four mineralized areas suggest that they are genetically related. Potassium-argon dating of hydrothermal alteration indicates that mineralization occurred almost simultaneously with, the emplacement of the quartz monzonite stock. It is suggested here that copper-silver-antimony ores are related to the porphyry system and were deposited in a subvolcanic environment peripheral to porphyry mineralization. Early stages of mineralization took place between 400° C and 491° C; sulfides continued to form as the system cooled below 300° C. During subsequent thermal metamorphism of the Main Zone deposit adjacent to the gabbro-monzonite complex, pyrrhotite and sillimamite formed in an aureole about 90 m wide. Temperatures during metamorphism are thought to be above 750°C and pressures to be less than 350 bar (about 1 km depth). / Science, Faculty of / Earth, Ocean and Atmospheric Sciences, Department of / Unknown

Sensing systems for mid-infrared wavelengths (2 to 5 μm) have important applications in biomedical, atmospheric and process gas monitoring systems. For lack of a suitable substrate, the full potential of GaSb-based materials, which are particularly suitable for operating in these wavelengths, are not completely realized. Hence, metamorphic growth technology, that allows the growth of semiconductor epilayers of arbitrary composition on any substrate, has been explored for antimony materials in this research. This makes the growth of device layers, containing arbitrary composition of GaSb-based materials, possible on commercially available 6"-GaAs substrates, and thereby reducing fabrication cost. Metamorphic growth of In(0.15)Ga(0.85)Sb was achieved using gas-source molecular beam epitaxy by growing compositionally graded ln(x)Ga(1-x)Sb buffer layers on a GaSb substrate. The effects of growth temperature on the quality of the metamorphic buffer layers along with the etching issues (both wet and dry) of GaSb-based materials were studied. Homo-junction n-i-p and p-i-n diodes were fabricated on In(0.15)Ga(0.85)Sb metamorphic layers. The dark current and its temperature dependence were measured and the extraction of area and perimeter components of dark current was done. The modeling of the components of dark current suggests that the diode currents were dominated by surface leakage. Surface passivation by silicon nitride and polyimide were investigated and our findings suggest that the former resulted in a better passivated surface. Responsivity measurements show that In(0.18)Ga(0.82)Sb diodes, metamorphically grown on GaSb substrates, have a cut-off wavelength of 2270 nm. Finally, hole (β) and previously unreported electron (α) ionization coefficients, at room temperature and 90° C, were extracted from these structures. The results show that α>β for ln(0.10)Ga(0.90)Sb for both temperatures. These photodetectors can be implemented m practical receiver systems for mid-infrared applications, such as atmospheric CO2 and methane detection at 2.0 μm. The possibility of growing antimony-based device layers on larger substrates, paves the way for future optoelectronic receiver systems operating at longer wavelengths, where both the photodetector and the amplifier can be integrated in the same module. / Thesis / Doctor of Philosophy (PhD)

<p> The de Haas-van Alphen effect has been used to measure the Fermi surface areas, cyclotron masses and Dingle temperatures in antimony and its alloys containing less than 0.3 percent tin. The Fermi surface of each alloy was similar to the pure antimony surface. However the hole surface increased in size and the electron surface shrunk since tin removes electrons from the alloy. The cyclotron masses increased and decreased for holes and electrons respectively, giving a definite indication of nonparabolic conduction and valence bands. The cyclotron masses were found from the temperature dependence of the dHvA amplitude after interfering dHvA frequency components were removed by a Fourier analysis technique. The Dingle temperature increased roughly linearily with tin concentration.</p> <p> A comparison of the hole and electron Fermi surface volumes with the number of tin atoms added to the alloys shows that one tin atom removes one electron from the alloy as expected from the unit valence difference between antimony and tin. This value is higher than that found by other workers using different techniques.</p> <p> The shapes of the energy bands along with the cyclotron masses have been compared with several band models. An ellipsoidal band provides a rough overall description of both holes and electrons while an ellipsoidal nonparabolic band describes the mass behaviour on alloying more accurately. A pseudopotential band calculated using the method and potential of Falicov and Lin (1967) was also compared with the data.</p> <p> The observed relative frequency changes were used to compare the data with the rigid band model of alloying. The bands are rigid for low concentrations. At higher concentrations there are deviations apparently caused by the cyclotron mass change and an axial ratio change in the hole Fermi surface.</p> / Thesis / Doctor of Philosophy (PhD)

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