<p>Poznavanje spektra x-zračenja kao i drugih osobina je od izuzetnog&nbsp; značaja&nbsp; kako za planiranje radijacione terapije tako i sa aspekta za&scaron;tite pacijenta i osoblja. Takođe, poznavanje svojstava&nbsp; neutrona&nbsp; nastalih&nbsp; u interakciji fotona sa materijalima<br />oko akceleratora, je od izuzetnog značaja sa dozimetrijskog aspekta. Poslednjih godina sve se vi&scaron;e upotrebljavaju linearni akceleratori bez homogenizacionog filtera tzv. FFF (<em>Flatteninig Filter Free</em>), a kako su karakteristike snopa u toma načinu rada akceleratora jo&scaron; uvek nedovoljno ispitane, njima smo posvetili posebnu pažnju. Urađena su i detaljna dozimetrijska merenja fotona kako u radu sa homogenizacionim filterom (FF) tako i bez njega (FFF), kao i dozimetrijsko merenje neutrona. Direktno merenje samog<br />spektra nekim od detektora (NaI ili HPGe) nije moguće zbog visokih intenziteta stoga smo u radu koristili indirektne metode i to aktivacionu analizu i atenuacionu analizu.<br />Urađena su detaljna dozimetrijska merenja ekvivalentne doze neutrona u terapijskoj sobi sa dva zaokreta hodnika i na osnovu rezultata predložena je korekcija metode za izračunavanje neutronske doze na ulaznim vratima.&nbsp; Fotoaktivacionimmerenjima, gde su se u oba načina rada terapijskog&nbsp; akceleratora pratile aktivnosti izomera ^115m In, ustanovljeno je da se kod dva tipa&nbsp; akceleratora&nbsp; (Elekta Versa HD, Varian TrueBeam)&nbsp; oblik spektra u visokoenergetskom delu znatno razlikuje, kao i da postoji razlika u obliku spektra na ivici polja i u njegovoj sredini.&nbsp; Atenuacionom analizom&nbsp; na osnovu&nbsp; standardnog metoda rekonstrukcije fotonskog spektra putem Laplasovih transforma, dobijene su izvesne razlike u oblicima spektara za dva režima rada. Takođe,&nbsp; rekonstrukcijom spektra putem odabira parametara korekcine funkcije koja bi teorijski oblik spektra (&Scaron;ifova funkcija) trebao da prevede u realan spektar za oba režima rada dobijene su izvesne razlike u oblicima spektra. Dozimetrijska merenja fotonske doze na ulaznim vratima terapijske sobe sa&nbsp; jednim zaokretom, sa i bez homogenizacionog filtera za različite veličine polja i sa i bez vodenog kanistera koji simulira pacijenta u snopu, pokazuju da je izmerena&nbsp; doza na ulaznim vratima u FFF modu rada uvek niža od izmerene doze u slučaju da se koristi homogenizacioni filter.</p> / <p>Knoweledge of the x-ray spectrum as well as other characteristics of the beam is of&nbsp; great&nbsp; importance both for the planning of radiotherapy as well as for the protection of patients and staff. Also, the knowledge of the neutron properties generated&nbsp; in the interaction of photons with materials around the accelerator is of great importance from the dosimetric aspect. In recent years, linear accelerators are increasingly used without a flattening filter, so-called FFF (<em>Flatteninig Filter Free</em>), and as the characteristics of the&nbsp; beam in this mode of operation of the accelerator&nbsp; are still insufficiently&nbsp; investigated, we paid special attention to them. Detailed dosimetric measurements of photons were performed both with (FFF) and without the flattening&nbsp; filter (FF), as well as the dosimetric measurement of the neutron. Direct&nbsp; measurement of the spectrum itself by detectors (NaI or HPGe) is not possible due to&nbsp; high intensities, therefore, we used indirect methods in this work, both activation analysis and attenuation analysis. Detailed&nbsp; dosimetric measurements of the&nbsp; neutron&nbsp; equivalent dose in the therapeutic&nbsp; room with two band maze&nbsp; were made and based on the results, correction of the method for calculating the neutron dose at the entrance door was proposed. It was found by photoactivation measurements, where the activities of the isomer ^115mIn were investigated, that in the two types of accelerators (Elekta Versa HD, Varian TrueBeam) the spectrum shape in the high-energy part is significantly&nbsp; different, and that there is a spectrum difference in the edge of the field and in the middle of the field. Attenuation analysis, based on the standard method of reconstructing the photon spectrum through Laplace transforms, showed&nbsp; some differences in the spectra of&nbsp; the two working&nbsp; modes&nbsp; of accelerators. Also, by reconstructing the spectrum by correction function&nbsp; that&nbsp; should transform&nbsp; the&nbsp; theoretical spectrum&nbsp; form (the Schiff function)&nbsp; into a real spectrum for both modes of operation, certain differences&nbsp; in spectrum shapes were&nbsp; obtained. Dosimetric measurements of the photon dose at the entrance door of treatment room&nbsp; with a single maze with and without a homogenizing filter for different field sizes and with and without a water canister&nbsp; which simulates&nbsp; the patient in a beam showed&nbsp; that the measured dose at the entrance door in the FFF mode is always lower&nbsp; than the measured doses in FF mode.</p>

A series of recent excavations on the 2nd Century AD Antonine frontier forts of the Midland Scottish valley, have produced results which suggest that the army was making its own pottery on an appreciable scale. This was at a time when pottery production was thought to have moved almost exclusively into civilian hands. The possible local ware groups identified by the excavations were largely independent of firm source indicators such as kiln and waster material and the number of available samples was often-small. A program of Neutron Activation and Thin Section petrological analyses was undertaken along with an investigation into Textural Analysis, a facet of the Petrological toolkit. The aim was both to define the site ware groups and a group of specialist vessels thought to be local to Scotland, the Mortaria, and to make statements as to their provenance. Although the Mortaria analysis was limited by problems of sample group size and availability, by improving the objectivity of the statistical handling of the derived data sets and developing methods for the high level study of textural data, the site ware groups were defined successfully at both the "intrall and "inter" site levels. The analyses also furnished interpretations as to the mode and nature of the site production schemes. Through the full analysis of' site Daub samples linked to more traditional provenancing techniques, in all but one case the ware groups could be assigned to the source sites, where contrasting production modes could be identified with military as opposed to civilian production. / SERC

A neutron activation analysis procedure for the simultaneous determination of Au, Pd and Ir, and separate determination of Os is described and applied to the determination of these metals in the Mount Albert ultramafic pluton, Quebec. The Mount Albert is an alpine-type ultramafic body whose petrography, geology and geochemistry has been discussed in some detail by MacGregor (1962, 1964). It consists mainly of serpentinized dunite and peridotite. However, it is distinguished by the presence of an eastern lobe which is essentially unserpentinized. In addition to ferromagnesians, two varieties of spinel including disseminated accessory chrome spinel and massive, discordant chromite veins or schlieren are important mineralogical constituents. Twenty samples were analyzed including 5 fresh dunites and peridotites, 8 serpentinized equivalents, 4 disseminated chrome spinels, 1 clinopyroxenite, and 2 massive chromite. The concentrations (in p. p. b.) of average fresh ultramafics and their serpentinized equivalents are:-------------------------------------- ---------------------Pd----Os----Ir----Au------------------------------------------- Fresh rocks------------7.7----7.2--2.5--0.99------------------------------------------- Serpentinized rocks---10----6.6--2.2---2.4-------------------------------------------- The piuton was intruded as a nearly solid mass of olivine and some orthopyroxene with about 15 weight per cent melt. A small concentration of the precious metals, a factor of 2 to 3, in the melt relative to crystalline phases appears to have occurred. The disseminated chrome spinel and massive chromite appear to concentrate the precious metals. In particular, Os and Ir content of the massive chromite is approximately 10 times that of fresh or serpentinized whole rocks. There is little change in average precious metal content with serpentinization. Pd shows a slight increase, and Ir and Os slight decreases in concentration with degree of serpentinization. Only Au appears significant to be enriched in serpentinized rocks where a twofold increase occurs. The variation in precious metal content of all four metals increase when the rocks are serpentinized: When normalized to chondrite meteorites, the precious metal data give fractionation trends similar to that of average chondrite. These trends are compatible with a model in which alpine ultramafics are regarded as residua from the partial melting of parental material of approximately chondritic composition. / Thesis / Master of Science (MSc)

No description available.

<p>Transition metals, such as iron, manganese, and copper are essential in the development and function of biological systems. However, disrupted levels of transition metals are highly cytotoxic, and metal homeostasis is strictly maintained in cells under normal conditions. The neuropathology of several brain disorders, such as Alzheimer’s disease and Parkinson’s disease has been linked to altered metal levels. This work focused on the measurement of iron, manganese, and copper, with the aim of better elucidating their role in brain disease.</p> <p>Two experiments were carried out in C57Bl/6 mice looking at metal homeostasis: <em>1.</em> following manganese injections typically administered in manganese-enhanced MRI animal studies, and <em>2.</em> following copper deficiency in a cuprizone model of demyelination. Metal measurements were made in the brain and visceral organs using X-ray fluorescence to measure iron and copper concentrations, and neutron activation analysis to measure manganese concentrations.</p> <p>In the MEMRI study in this work, in addition to the expected manganese concentration increases in brain regions, a statistically significant decrease in iron concentration in the thalamus was found. This change in iron levels in the thalamus following manganese injections should serve as a caution that care should be taken when interpreting signal changes in brain regions.</p> <p>The cuprizone study in this thesis confirmed that copper levels are reduced following cuprizone administration. Surprisingly, manganese concentrations were significantly higher in several brain regions that have demyelination in this model, but not iron or copper. The mechanism of cuprizone toxicity was related to manganese neurotoxicity that may contribute to demyelination.</p> / Master of Science (MSc)

This study describes the technique and procedures used for the simultaneous determination of elements involved in Instrumental Neutron Activation Analysis, applied to some geological samples as a sensitive and non-destructive tool. Using Isotopic Neutron Source, the delayed gamma-rays emitted due to neutron capture have been applied for the investigation of the elemental constituents and concentrations of major, minor and trace elements in such samples. The experimental investigations were carried out at the scale of researcher's practices at the chosen site by measuring soil/rock nutrient contents from hydrologically isolated farmland/site plots. Using detailed sampling procedures with special precautions, against contaminations, to yield meaningful results, soil/rock samples have been collected from selected areas of East Gojjam, pulverized, homogenized and prepared for irradiation. The samples were properly prepared together with known standards of potassium iodide or cupric sulphate or arsenic trioxide (one /or both at a time), and simultaneously irradiated in to isotopic neutron ux in the same irradiation position. After activation, the samples were subjected to gamma-ray spectrometry, using a high-purity germanium detection system and computerized multichannel analyzer. The gamma-ray spectra from the irradiated samples were measured by high resolution gamma-ray spectrometry with a calibrated germanium detector. Both qualitative and quantitative approach to data collection and analysis were used in order to gain insight into what should be acceptable to the community. The results obtained have a practical interest in view of possible applications to the technology of extraction and exploration of a variety of industrial, metallic, cement minerals, and geothermal energy and coal deposits. These results tend to agree with the lowest values reported in the literature, and the analytical precision is su cient for the determination of the standard deviation of the distribution of all elements in East Gojjam and these results were brie y discussed within the text of this research work. In carrying out the analysis, the best and most convenient method being the Instrumental and /non-destructive Neutron Activation Analysis was adopted, and NAA has matured and attained analytical competence providing not only rapid, quantitative, qualitative, simultaneous, multi􀀀element analysis but also crucial validation support to programmes using di erent analytical techniques. This method of analysis is generally multi-element and experimental conditions can be designed to be non􀀀destructive to the sample, and it plays a leading role among analytical techniques in the eld of environmental research related to human, animal and plant health. Studies of di erent radionuclide and trace elements in the environmental samples are very important for health physics, research and education. Many forms of elements are possible in environmental samples which may be hazardous for human being, animals and also plants. Most of them have the potential for both benefcial and harmful effects / Environmental Sciences / D. Phil. (Environmental Science)

No description available.

Fieldwork in the Zemplen Mountain area of north-eastern Hungary showed that there are at least eight geological sources of obsidian here, five of which have obsidian of a workable quality. There are a further three sources in the Slovak Zemplen, all of which provide workable obsidian. Sources in Central Slovakia are highly devitrified and not useable, and reported sources in Rumania had been discounted earlier (Nandris, 1975). Forty-six samples of obsidian from the Zemplen sources, and 293 pieces from 87 archaeological sites in Central and Eastern Europe, were analysed by neutron activation analysis for 15 trace and two major elements. The trace elements used included those which are geochemically likely to show the greatest variation between different obsidian sources, and which are not badly affected by devitrification and hydration of the obsidian, for example the rare earth elements. The analytical data was processed using Cluster Analysis. 242 of the archaeological samples came from Slovak sources, 22 from Hungarian sources, 9 from Lipari and 5 from Melos. In addition, 6 samples were tentatively assigned to Carpathian sources, and 9 could not be assigned to any source. Obsidian from the Zemplen Mountains was distributed up to a distance of approximately 480 km from the sources; it was used extensively in Slovakia and Hungary and reached southern Poland, Austria, Moravia, central Yugoslavia, north-east Italy and central Rumania. Obsidian use in central and eastern Europe began in the Mousterian period. The earliest pieces analysed were Aurignacian and came from Hungarian sources. Later, in the Gravettian, Slovakian sources began to be exploited and remained predominant until obsidian use declined sharply in the Later Neolithic, and Copper and Bronze Ages. The Carpathian obsidian distribution overlaps with the Liparian distribution at one site in north-east Italy. There is no evidence for an overlap with Aegean or Near Eastern sources. The rate of fall off of obsidian away from the sources suggests a down-the-line trading mechanism.

O presente trabalho procurou aperfeiçoar um código criado para calcular os parâmetros k0 e Q0, denominado COVAR, adicionando um outro método para a determinação do fator k0 e aprimorar a análise de covariância existente, criando uma nova versão: COVAR v4.1. O presente trabalho também desenvolveu um novo método de cálculo para os parâmetros &alpha; e vários fatores k0 em um único ajuste de mínimos quadrados, por meio de uma metodologia inédita, utilizando matrizes de covariância e todas as incertezas parciais envolvidas. Para aplicação deste método, outro código foi desenvolvido, denominado AKFIT v2.1, no qual possui a capacidade de efetuar dois ajustes, linear e não-linear, na determinação de &alpha; e k0 para várias irradiações. Foi utilizado um conjunto de dados com irradiações realizadas nos anos de 2008 e 2010, pelo Laboratório de Metrologia Nuclear (LMN) e por meio do reator nuclear IEAR-1, do IPEN-CNEN/SP, correspondendo aos radionuclídeos 95Zr, 65Zn, 69mZn, 46Sc, 140La e 60Co, resultando em 21 conjuntos de dados a serem analisados para verificar o desempenho dos códigos criados. Para COVAR v 4.1, os resultados do cálculo alternativo para o fator k0 foram próximos dos valores obtidos pelo método original do programa e foram consistentes com a literatura. Para AKFIT v2.1, realizou-se ajustes com ambas irradiações simultâneas e separadas. Os modelos ajustados concordaram com a literatura. O valor de &alpha; foi de 0,0025(83), que está de acordo com resultados obtidos anteriormente pelo LMN. As correlações entre os parâmetros k0 se comportaram como esperado, com valores menores entre diferentes elementos e maiores entre elementos iguais com diferentes energias e usando o mesmo comparador. Pode-se concluir que os métodos propostos foram capazes de calcular os valores de k0, com AKFIT v2.1 sendo uma nova técnica no qual é possível determinar dois parâmetros, &alpha; e k0, ao mesmo tempo, de modo rápido e preciso. Espera-se que o código AKFIT possa ser aperfeiçoado, adicionando mais parâmetros, como Q0 e f, tornando-o uma ferramenta de ajuste completo para a determinação de todos os parâmetros essenciais do Método k0 de AAN. / The present work aims to improve a code for calculating k0 and Q0 parameters, called COVAR, adding another method of calculating k0 factor and improving the covariance analysis, creating a new version: COVAR v4.1. The present work also aims the development of a new method of calculating the alpha and several k0 parameters in a single least square fit, by means of a novel methodology, using covariance matrices and all partial uncertainties. For the calculations applying this new method, another code was developed, called AKFIT v2.1 which performs linear and non-linear fittings for the determination of alpha and k0 parameters for several irradiations in different periods. We used a database with irradiations in the years 2008 and 2010 performed at the IEAR-1 nuclear reactor of the IPEN-CNEN/SP, by the Nuclear Metrology Laboratory (LMN), corresponding to radionuclides 95Zr, 65Zn, 69mZn, 46Sc, 140La and 60Co and resulting in 21 data sets which were analyzed in order to verify the performance of COVAR4.1 and AKFIT2.1. For COVAR v4.1, the results with the alternative calculation of k0 factor were close to the already existing calculation and were consistent with the literature. For AKFIT v2.1 fittings were performed with both irradiations simultaneously and separately. The fitted models agreed with the literature. The &alpha; value was 0,0025(83), which agrees with previous results obtained by the LMN. The correlations between the parameters k0 behaved as expected, with smaller values between different elements and greater correlations between equal elements with different energies and using the same comparator measurement. It can be concluded that the proposed methods were able to calculate the values of k0, with AKFIT v2.1 being a new technique in which it is possible to determine two parameters, alpha and k0 at the same time, quickly and accurately. It is expected that AKFIT code can be improved by adding more parameters, such as Q0 and f, by making a complete fitting for the determination of all the main parameters for the k0 NAA method.

Alimento base da dieta dos brasileiros, o feijão é a leguminosa de maior importância para consumo direto no mundo. Inúmeras pesquisas em relação às propriedades nutricionais do feijão comum e também do feijão de corda têm sido realizadas, no intuito de avaliar sua composição centesimal, mineral e fatores antinutricionais. Em relação à qualidade das determinações analíticas, sabe-se que os materiais de referência certificados (CRMs) estão se tornando cada vez mais necessários em procedimentos de medição. Contudo, ainda há escassez de CRMs para atender às demandas em todos os setores produtivos, especialmente na agricultura. O domínio da tecnologia para sua produção representa, portanto, um avanço estratégico, por colocar o país em condições de fornecer materiais específicos às próprias necessidades. Dessa forma, este trabalho envolveu a primeira etapa para elaboração de um material de referência certificado de feijão, com a caracterização química e nutricional dos principais tipos comerciais disponíveis no mercado, das espécies Phaseolus vulgaris L. (feijão comum) e Vigna unguiculata (feijão caupi), buscando atender demandas metrológicas específicas da pesquisa e da indústria alimentícia. Foram coletadas 55 amostras de feijão de dez tipos comerciais diferentes no varejo da cidade de Piracicaba. Determinaram-se os elementos químicos Br, Ca, Co, Cs, Fe, K, Mo, Na, Rb, Sc e Zn utilizando análise por ativação neutrônica, a composição centesimal empregando metodologia preconizada pela AOAC e o fator antinutricional ácido fítico segundo o método descrito por Grynspan e Cheryan (1989). Os resultados mostraram diferença significativa entre os tipos comerciais de feijão (p<0,05) para Br, Cs, Co, K, Mo, Na e Zn, e também para os teores de proteínas, cinzas, umidade e ácido fítico. O feijão fradinho, da espécie Vigna unguiculata, apresentou diferenças consideráveis em relação ao feijão comum da espécie Phaseolus vulgaris L., tendo a maior concentração média de Na e as menores concentrações médias de Ca, Co, K e cinzas (p<0,05). O feijão preto apresentou as maiores concentrações médias de Ca, Co, Fe, proteínas e ácido fítico, enquanto o feijão cavalo as maiores concentrações médias de K, Mo e Zn (p<0,05). O feijão carioca apresentou valores médios próximos à média global para todos os parâmetros avaliados, exceto para ácido fítico. Alta variabilidade foi identificada para Br, Cs, Mo, Na, Rb e Sc dentro de um mesmo tipo comercial, enquanto baixa variabilidade foi observada para K, Zn, cinzas e proteínas. O conjunto de dados resultantes da caracterização química das 55 amostras de feijão mostra que os tipos comerciais carioca, preto e fradinho são os mais indicados para produção de material de referência certificado. Considerando o critério de comutatividade, o feijão carioca pode ser utilizado para produzir um material de referência que represente todos os tipos comerciais estudados / Basic food of the Brazilian diet, beans are the most important leguminous for direct consumption in the world. Numerous researches on the nutritional properties of common bean and string bean have been performed in order to assess their centesimal and mineral composition as well the antinutritional factors. Regarding the quality of the analytical determinations, it is known that the certified reference materials (CRMs) are becoming increasingly necessary in measurement procedures. However, there is still lack of CRMs to meet the demands from all productive sectors, especially agriculture. Mastering the technology for their production therefore represents a strategic step forward, to put the country in a position to provide specific materials to own needs. Thus, this work involved the first step in developing a bean certified reference material, with chemical and nutritional characterization of the main commercial types available in the market, from the species Phaseolus vulgaris L. (common bean) and Vigna unguiculata (cowpea), meeting the specific metrological demand of research and food industry. In the retail market of the city of Piracicaba, 55 bean samples from ten different commercial types were collected. The chemical elements Br, Ca, Co, Cs, Fe, K, Mo, Na, Rb, Sc and Zn were determined by nêutron activation analysis, the proximate composition using methodology recommended by the AOAC and the anti-nutritional factor phytic acid, according to the method described by Grynspan and Cheryan (1989). The results showed significant differences between commercial bean types (p<0.05) for Br, Cs, Co, K, Mo, Na and Zn, and also for protein, ash, moisture and phytic acid. The black-eyed pea from Vigna unguiculata species showed considerable differences from the common bean Phaseolus vulgaris L. species, having the highest average concentration of Na and the lowest average concentrations of Ca, Co, K and ash (p<0.05). The black bean had the highest average concentrations of Ca, Co, Fe, proteins and phytic acid, while horse bean the highest average concentrations of K, Mo and Zn (p<0.05). The common bean showed mean values close to the global average for all parameters, except for the phytic acid. High variability has been identified for Br, Cs, Mo, Na, Rb and Sc within a commercial type, while low variability was observed for K, Zn, ash, and proteins. The data set resulting from the chemical characterization of 55 samples indicates that the commercial types common bean, black bean and black-eyed pea are more indicated for the production of the certified reference material. Considering the commutability criteria, the common beans could be used to produce a reference material representative of all commercial types studied