Made available in DSpace on 2014-10-09T12:42:43Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T13:57:17Z (GMT). No. of bitstreams: 1 05408.pdf: 10272523 bytes, checksum: f76b1c2fee05365386402c5aa1063133 (MD5) / Dissertacao (Mestrado) / IPEN/D / Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP

Made available in DSpace on 2014-10-09T12:36:08Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T13:59:22Z (GMT). No. of bitstreams: 1 03968.pdf: 1649642 bytes, checksum: 95e6e89ec5ba0b4cdf75c95e00c7fb9a (MD5) / Dissertacao (Mestrado) / IPEN/D / Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP

Made available in DSpace on 2014-10-09T12:26:04Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T14:01:55Z (GMT). No. of bitstreams: 1 12888.pdf: 1126545 bytes, checksum: 742903efa046bf9be44f8393dbefca25 (MD5) / Dissertacao (Mestrado) / IEA/D / Instituto de Quimica, Universidade de Sao Paulo - IQ/USP

Made available in DSpace on 2014-10-09T12:25:39Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T14:03:44Z (GMT). No. of bitstreams: 1 06789.pdf: 8523465 bytes, checksum: cf621ab32dfdca4609c1f77439a6f0f7 (MD5) / Dissertacao (Mestrado) / IPEN/D / Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP

Made available in DSpace on 2014-10-09T12:55:19Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T14:04:56Z (GMT). No. of bitstreams: 0 / O Laboratório de Análise por Ativação com Nêutrons (LAN) do Instituto de Pesquisas Energéticas e Nucleares (IPEN), utiliza esta técnica analítica multielementar, baseada na irradiação de uma amostra por um feixe de nêutrons oriundos de um reator nuclear, que induz a radioatividade; que é medida em um espectrômetro de raios gama, para a obtenção dos espectros de raios gama. Neste trabalho é implementado um software denominado de SAANI (Software Análise por Ativação com Nêutrons Instrumental) para análise de espectros de raios gama, desenvolvido para os usuários do laboratório LAN-IPEN, com a filosofia de software livre, para a substituição do software existente VISPECT/VERSÃO 2, e tem como características principais: tornar a interface mais amigável; facilitar a padronização dos procedimentos realizados pelos pesquisadores, estudantes e técnicos; ser extensível com a utilização da tecnologia de plugins; multiplataforma; código livre. O software foi desenvolvido utilizando a linguagem de programação Python, a biblioteca gráfica Trolltech Qt e algumas de suas extensões científicas. Os resultados preliminares obtidos utilizando o software SAANI foram comparados aos obtidos com o software existente e foram considerados bons. Algumas diferenças encontradas foram verificadas oriundas de erros de precisão na implementação do software. O software SAANI está instalado nos computadores de usuários selecionados para a execução de rotinas de análise para uma maior verificação de sua robustez, precisão e usabilidade. / Dissertação (Mestrado) / IPEN/D / Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP

Made available in DSpace on 2014-10-09T12:24:48Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T14:04:54Z (GMT). No. of bitstreams: 1 00050.pdf: 2437062 bytes, checksum: 5286154f7903e5b5df158083e8b39dd6 (MD5) / Tese (Doutoramento) / IEA/T / Instituto de Quimica, Universidade de Sao Paulo - IQ/USP

Made available in DSpace on 2014-10-09T12:38:26Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T14:05:29Z (GMT). No. of bitstreams: 1 05827.pdf: 4162110 bytes, checksum: 4818bf19a034f75fcbef60b0310a8176 (MD5) / Dissertacao (Mestrado) / IPEN/D / Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP

Made available in DSpace on 2014-10-09T12:26:02Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T14:06:50Z (GMT). No. of bitstreams: 1 00378.pdf: 987505 bytes, checksum: b6587927b6c5975dc6119eb53714b845 (MD5) / Dissertacao (Mestrado) / IEA/D / Instituto de Energia Atomica - IEA

Deaerated acidic, neutral, and basic aqueous N₂0 solutions were irradiated with Co-60 γ -rays in order to: 1) determine the primary yields, and 2) resolve anomalies in relative rate constant ratios of the type k(e⁻aq +S)/k(e⁻aq +N₂0). The yields of the gaseous products N₂, 0₂, and H₂ were determined as a function of both pH and [N₂0]. About 10⁻² M N₂0 is commonly used to evaluate relative rate constant ratios, but this [N₂0] scavenges not only hydrated electrons (e⁻aq ) but also another species, X, (where G(X) = 0.65±0.1), resulting in erroneous rate constant ratios. Yields of primary species found were: Ge⁻aq = 2.4±0.1, G H₂O* ̴ 1.6, and G,H₂⁺, = 0.35±0.05. Kinetic competition studies of the reaction of N₂0 and H⁺ with e⁻aq were undertaken in the concentration ranges 3 x 10⁻⁵ to 2 x 10⁻⁴ M H⁺ and 10⁻⁴ to 10⁻³ M N₂O. The results cannot be explained by: 1) simple competition; 2) charge transfer, or 3) two species being scavenged. They may be explained by assuming a conversion of N₂O to another species in acid solution. This acid species, suggested to be H₂N₂O₂, is apparently five times less reactive toward e⁻aq than is N₂0 in neutral solution. Deaerated neutal N₂0 solutions were irradiated at extremely high intensity with very short pulses of 0.52 Mev electrons. The yields of the gaseous products N₂, O₂, and H₂ were studied in order to examine an expected decrease in solute products, and to determine primary yields at high dose rates. As predicted, significant scavenging occurs for high dose rates only at N₂0 concentrations an order of magnitude larger than those at low dose rates. Also the scavenging, which is complete at ~ 10⁻² M N₂O for low intensity irradiations, is not complete at 2.6 x 10⁻² M N₂0 for high intensity irradiations. These results indicate that the radiation yield of scavengable hydrated electrons is significantly larger at the high intensity used. The yield of hydrogen in pure water (G(H₂) = 1.15±0.2) can be explained on the basis of inter-spur reactions of e⁻aq, H, and OH. / Science, Faculty of / Chemistry, Department of / Graduate

The subject of whether fluorine (F) is detrimental to human health has been controversial for many years. Much of the discussion focusses on the known benefits and known detriments to dental care and problems that fluorine causes in bone structure at high doses. It is therefore desirable to have the means to monitor fluorine concentrations in the human body as a means to directly assess exposure. A monitoring tool could be applied in studies of human health and perhaps answer some of the questions regarding levels at which fluorine has protective effects and negative health consequences. This thesis presents work in the further development of a low risk non-invasive method for the monitoring of fluorine in human bone. The work was based on the technique of neutron activation analysis (NAA). Fluorine accumulates in bone as a long term storage site following exposure. In this thesis, the McMaster Tandem accelerator was used to produce neutrons through the 7Li(p,n)7Be reaction, measuring F levels in the human hand bone using IVNAA. The gamma rays emitted through the 19F(n,γ )20F reaction are measured using nine NaI(Tl) detectors with 4π geometry. Four published papers are presented in this thesis. The main outcome of the first publication was the development of a new phantom. This was needed to reduce the aluminum contamination. The main outcome of the second publication was a series of improvements to the method for the in vivo measurement of bone fluorine using NAA of the new phantoms. In the third publication the best hand position and neutron flux map in the irradiation cavity were determined through both Monte Carlo simulation (FLUKA) and experimental methods. Finally, the fourth publication describes the utility of the improved technique in a pilot study of environmentally exposed people. The overall conclusion from this thesis work is that a low risk monitoring tool, based on an NAA technique, has been developed which is capable of monitoring fluorine in urban Canadians. The technique can now be applied in studies of human health. / Thesis / Doctor of Philosophy (PhD)