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O objetivo deste estudo foi aplicar técnicas de geoquímica de elementos maiores, menores e isótopos de Sr e Nd para identificar contaminação por fosfogesso em sedimentos fluviais da bacia hidrográfica Mogi/Piaçaguera. Para isto, foram analisados perfis de sedimento das margens dos rios Cubatão, Pereque, Mogi (montante, meio e jusante), Piaçaguera e Jurubatuba, inseridos no alto estuário santista, assim como solos, rochas e águas superficiais. Os métodos utilizados foram fluorescencia e difratometria de raios-x, microscopia ótica e analises isotópicas de Sr e Nd. Os resultados demonstraram fator de enriquecimento de Sr, Nd, Nb, La, F e Ce nos sedimentos superficiais do Rio Mogi jusante, comparado aos demais sedimentos fluviais analisados. As composições isotópicas dos sedimentos fluviais regionais foram dentro do padrão das rochas e solos da bacia hidrográfica. A exceção se deve aos sedimentos fluviais superficiais do Rio Mogi jusante que apresentaram assinaturas química e isotópica semelhantes do fosfogesso. O cálculo de proporção de mistura de composições isotópicas de Sr e Nd proveniente do fosfogesso indicou significativa discrêpancia para os dois métodos, de até 6% para Sr e 35% para Nd. Pelo contrário, diagramas 143Nd/144Nd e 87Sr/86Sr apresentaram proporções menores de 10%, coerentes com estudo da literatura que estimou de 13% a 18% a solubilização do fosfogesso em água. A normalização das composições isotópicas com a água do mar (e87Sr) dos resultados para extração parcial (ácido acético) indicou valores de e87Sr semelhantes para solos, sedimentos e águas superficiais da bacia hidrográfica, inclusive, levanta-se hipotese da influência da maré nos sedimentos do Rio Jurubatuba, com padrão isotópico semelhante da água do mar. Distintamente, confirmaram-se assinaturas isotópicas do fosfogesso nos sedimentos do Rio Mogi jusante. Em suma, isotopos de Sr e Nd demonstraram ser importantes ferramentas na identificação de plumas de contaminação antrópica, como também na identificação das prováveis fontes destas anomalias. / This objective of this study was applying geochemical techniques of major and minor elements, aswell as Sr. And Nd isotopes to identify contamination by phosphogypsum in fluvial sediments in the hydrografic basin of Mogi/Piaçaguera. Profiles of sediments from Cubatão, Pereque, Mogi (upstream,middle and downstream), Piaçaguera and Jurubatuba rivers margins, inserted in the high Santista stuary, as well as soils, rocks and superfial waters were analysed. The methods used were fluorescence and difratometria of X-rays, optical microscopy and isotopic analyses of Sr and ND. The results showed a factor of enrichment of Sr. Nd. NB, La, F and Ce in surface sediments of the Rio Mogi jusante, compared to other fluvial sediments analysed. The isotopic compositions of regional fluvial sediments were in accordance with rocks pattern and the hydrografic basin soils. The exception is due to surface fluvial sediments of the Rio Mogi jusante, which showed chemical and isotopic signatures similar to phosphogypsum. The calculation of proportion of isotopic composition mixtures of Sr. And Nd resulted from phosphogypsum indicated a significative discrepance for these two methods of up to 6% to Sr and 35% to Nd. On the contrary, 143Nd/144Nd and 87Sr/86Sr dyagrams presented minor proportions of 10% in coherence with the literature study, which estimated 13% to 18% the solubilization of phosphogypsum in water. The isotopic compositions normalization with sea water (e87Sr) of results for partial extraction (accectic acid) showed the value of e87Sr similar for soils, sediments and surface waters of the hydrografic basin. The hypotesis of the tidal influence in sediments of Rio Jurubatuba was arised, with a isotopic pattern similar to sea water. In a distinct way, the isotopic signatures of phosphogypsum in sediments of Rio Mogi jusante were confirmed. In summary,isotopes of Sr and Nd showed that are significant tools in the identification of plumas of antropic contamination, as well as in the identification of probable sources of these anomalies.

Fundamental research on the growth of porous anodic alumina (PAA) films has been undertaken for many years because of the complexity of the processes involved and the wide range of commercial applications. In this study, a tungsten tracer approach has been used to determine the influences of current density and electrolyte temperature on the incorporation of the tracer and its distribution and consequently, the growth mechanisms of PAA films. The efficiencies of growth of PAA films, formed during anodizing at 5 mA cm-2 in the three major forming acids at 25°C, are ~60%, due to loss of outwardly migrating Al3+ ions at the film/electrolyte interface. Thus, only the inwardly migrating O2- ions contribute to formation of the anodic oxide at the film/metal interface. The pores are developed due to flow of alumina from beneath the pore base regions toward the cell walls, which is indicated by distortion of the incorporated Al-W alloy layers and retention of the tungsten species within the anodic films. PAA films formed at a low range of current densities (<2 mA cm-2) develop by a field-assisted dissolution mode, with significant losses of aluminium and tungsten species to the electrolyte, and low expansion factors of less than 1.2. Conversely, films formed at current densities ≥2 mA cm-2 grow by a flow mechanism: flow of film material transports the alumina oxide, including the incorporated tungsten tracers, from the barrier layer regions to the cell walls, resulting in relatively thicker films at higher current densities and retention of the tungsten within the films. The tungsten remains mainly within the inner cell region of the films, with a tungsten-free region present next to the pore wall. The efficiency of film growth increases from ~0.29 to ~0.73 with increase of current density from 0.5 to 30 mA cm-2, and from ~0.26 to ~0.88 with increasing current density between 0.5 and 50 mA cm-2 for anodizing in sulphuric and oxalic acids respectively.Comparatively, for PAA films formed at 15 mA cm-2 in oxalic acid, reduction of electrolyte temperature from 20 to 1°C gives rise to a slight increase of the anodizing efficiency from ~0.67 to ~0.74; the film expansion factor also increases from ~1.32 to ~1.43. The previous arises from reduced field-assisted ejection of Al3+ ions at the decreased electrolyte temperature.Anodizing of the aluminium substrates in phosphoric acid or neutral phosphate solution generates barrier anodic alumina films and the barrier layers of porous films respectively, which comprise phosphorus-containing outer regions and a phosphorus-free inner regions. The phosphorus-containing outer region accounts for ~0.67 of the barrier films and the ~0.80 of the barrier layer of the porous films. Further, the distributions of phosphorus species are not significantly affected by the incorporation of the tungsten tracer nanolayer into the films; the influence of the phosphorus species on the outward migration of the tungsten species is also negligible.This tungsten tracer study suggests a significant influence of the flow of alumina oxide, under the high electric field, on the formation of PAA films at current densities ≥2 mA cm-2.

Flow visualization techniques have recently been applied for the investigation of various cryogenic flows of liquid helium. Particle image velocimetry and particle tracking velocimetry techniques, proven in the past as very fruitful in many scientific and industrial areas of research, are being used for the analysis of cryogenic flows. The Joint Low Temperature Laboratory at the Charles University in Prague is the first in Europe to employ flow visualization techniques to investigate liquid helium flows. The approach had to be optimized due to a number of technical and fundamental dificulties, i.e., the optical access to the helium bath and choice of suitable tracer particles. Water experiments at room temperature were performed to prove that the experimental apparatus is well-suited for the low-temperature experiments performed as the main part of the work. The latter focused on thermal counter flow. The results from both, room-temperature experiments and low-temperature experiments are discussed and positively compared with well-known theoretical results.

An experimental mine simulator was constructed which will be used to conduct tracer gas experiments in the laboratory. The test apparatus simulates a mine in a tabular deposit and is modular and simple and can be easily rearranged to represent a variety of mine geometries. The apparatus is appropriate for the use of tracer gases by being both airtight and open-circuit (exhausting to the atmosphere) and by maintaining turbulent flow throughout the model, ensuring the tracer gas is fully dispersed. The model features ports for injection and sampling of tracer gases, which represent boreholes present in an actual mine. The model is designed, in part, for the practice of tracer gas release and sampling methods in the laboratory. Valves on the apparatus represent ventilation controls, such as stoppings or regulators, or changing resistances in a mine, such an increase in resistance due to a roof fall or a decrease in resistance due to stoppings being destroyed. The relative resistances of airways can be changed by changing the status of the valves to represent different states of the ventilation controls. The mine simulator should serve as a tool for identifying and investigating novel tracer gases, developing a procedure for performing ventilation surveys using multiple tracer gases, and eventually developing a method for remotely inferring ventilation changes using tracer gases. / Master of Science