Fungi play important geoactive roles in the biosphere, particularly element biotransformations and biogeochemical cycling, metal and mineral transformations, decomposition, bioweathering, and soil and sediment formation. Fungi can apply various mechanisms to effect changes in metal speciation, toxicity and mobility, mineral formation and/or mineral dissolution. This research has examined fungal roles in bioweathering and bioleaching of zinc sulfide ore, together with an investigation of the role of fungal phosphatases in the bioprecipitation of uranium and lead when utilising an organic phosphorus-containing substrate as the sole phosphorus source. The results obtained revealed that test fungal species showed bioweathering effects on zinc sulfide ore, and clear evidence of biotransformation and bioleaching of zinc sulfide was obtained after growth of A. niger. The formation of zinc oxalate dihydrate resulted from oxalic acid excretion. The formation of uranium- and lead-containing biominerals after growth of yeasts and filamentous fungi with organic phosphorus sources have also been demonstrated and characterized. Test fungi were capable of precipitating uranium phosphate and pyromorphite, and also produced mycogenic lead oxalate during this process. This work is the first demonstration that filamentous fungi are capable of precipitating a variety of uranium- and lead-containing phosphate biominerals when grown with an organic phosphorus source. The role of fungal processes in the bioweathing and bioleaching of mineral ores, and the significance of phosphatases in the formation of uranium and lead secondary minerals has thrown further light on potential fungal roles in metal and mineral biogeochemistry as well as the possible significance of these mechanisms for element biorecovery or bioremediation.

O Brasil está entre os dez países que mais desperdiçam alimentos, com cerca de 35% da produção agrícola indo para o lixo. O processamento agroindustrial de alimentos é uma das atividades que mais geram resíduos, com aproximadamente 50% de matéria-prima sendo descartada. A falta de informações sobre a qualidade nutricional desses subprodutos agroindustriais não possibilita seu potencial aproveitamento na fabricação de produtos alimentícios. Neste contexto, o objetivo do trabalho foi realizar a caracterização química de subprodutos resultantes do processamento industrial de frutas e vegetais e do beneficiamento de cereais. Os elementos químicos Br, Ca, Co, Cr, Cs, Fe, K, La, Na, Rb, Sc e Zn foram determinados através da análise por ativação neutrônica instrumental, a composição centesimal, através de métodos preconizados pela AOAC, os fatores antinutricionais, através das determinações de ácido fítico e taninos e a disponibilidade dos nutrientes in vitro para os elementos Ca, Fe, K e Zn e pelo sistema de células Caco-2 para o Fe. A maioria das amostras contém alto teor de fibras e proteína e baixo teor de lipídeos e valor calórico. O farelo de arroz, a casca da semente de cupuaçu, a semente de cupuaçu e o bagaço de framboesa apresentaram as maiores concentrações de ácido fítico, entre 19,9 e 10,7 mg g-1. Já a casca de uva apresentou a maior quantidade de taninos (23,8 mg/g de catequina). As amostras apresentaram boa disponibilidade in vitro de Ca e Zn. Porém, para Fe e K, os valores ficaram abaixo de 10% disponível para a maioria das amostras. Na análise de biodisponibilidade através do sistema de células Caco-2, a amostra que apresentou maior quantidade de ferritina foi a casca de pepino (56,8 ng ferritina/\'mü\'g proteína). Observou-se que os subprodutos, geralmente, apresentam quantidade maior ou igual de nutriente que a parte usualmente consumida do alimento, além de apresentar disponibilidade de nutrientes compatível com outros alimentos de origem vegetal. Os dados sugerem que os subprodutos agroindustriais são potenciais ingredientes para a indústria alimentícia, podendo agregar valor nutricional em novos produtos. Estudos futuros e mais específicos para cada subproduto devem ser considerados, como análise sensorial e maneiras de aumentar a qualidade nutricional dos subprodutos / Brazil is amongst the ten countries that mostly waste food, with about 35% of agricultural production going to the trash. The agro-food processing is one of the activities which generate high amount of residues, with approximately 50% of raw material being discarded. The lack of information on the nutritional quality of agroindustrial byproducts does not enable its potential use in the manufacture of food products. In this context, the aim of this study was the chemical characterization of the by-products of industrial processing of fruits and vegetables and grain processing. The chemical elements Br, Ca, Co, Cr, Cs, Fe, K, La, Na, Rb, Sc e Zn were determined by instrumental neutron activation analysis. The proximate composition was evaluated by methods recommended by AOAC. The antinutritional factors, through the determination of phytic acid and tannins. The availability of nutrients in vitro for Ca, Fe, K and Zn and through the Caco-2 cells for Fe. Most samples contain high fiber and protein and low lipid content and calorific value. Rice bran, the peel of cupuaçu seed, the cupuaçu seed and the raspberry bagasse had the highest concentrations of phytic acid, between 19.9 and 10.7 mg g-1. The grape peel showed the highest amount of tannins (23.8 mg / g of catechin). The samples showed good in vitro availability for Ca and Zn, but the values for K and Fe were below 10% available for most samples. In the analysis of bioavailability through the Caco-2 cells system, the sample that showed the highest amount of ferritin was the peel of cucumber (ferritin 56.8 ng/\'mü\'g protein). It could be observed that the by-products generally exhibit similar or larger amounts of the nutrient than the food usually consumed, and nutrients availability compatible with other plant origin food. The data suggest that the agroindustrial byproducts are potential ingredients for the food industry and can add nutritional value to new products. Future studies more specific to each by-product should be considered like sensory analysis and ways to increase the nutritional quality of by-products

In this study the unique Magotteaux Mill® system was used to control the grinding chemical conditions, which may be adjusted by varying grinding media, purging gas and pH, during grinding. An electrochemical apparatus was used to investigate oxidation-reduction behaviour of grinding media and sulphide mineral electrodes, as well as their galvanic interaction in-situ of the Magotteaux Mill®. Galvanic interaction between the grinding media (mild steel, 15% chromium, 21% chromium and 30% chromium media) and the sulphide minerals (bornite, arsenopyrite and pyrite) was initially quantified in-situ of the mill by electrochemical techniques under different grinding atmospheres (nitrogen, air and oxygen). An innovative mathematical theoretical model was developed to describe the effect of galvanic interaction on oxidation rates of the grinding media during grinding, which was verified by the experimental data. Galvanic interaction enhanced the oxidation of the grinding media and produced more oxidized iron species in the mill discharge. It was observed that oxidized iron species (EDTA extractable iron) was linear with galvanic current between the grinding media and the sulphide minerals, in agreement with the prediction of the theoretical model. The effect of grinding conditions on pulp chemistry, surface properties and floatability was investigated by the measurement of dissolved oxygen (DO), pH, pulp potential (Eh), ethylene diamine-tetra acetic acid (EDTA) extraction, X-ray photoelectron spectroscopy (XPS) and floatation recovery. / PhD Doctorate

The flotation process has been used and extensively researched over the past 100 years; however some aspects still remain a great mystery. While most research in the past has focussed on the pulp phase of the process, recently there has been a significant trend towards investigating the froth phase. This study focuses on the froth phase and investigates the processes that occur within this zone in a well defined and controllable system under particular operating conditions, namely changes in frother type and concentration, as well as particle type and concentration.

An investigation of the geological resources of the Southern Highlands was undertaken and over two hundred samples were collected and examined for possible use as stoneware ceramic ingredients. Thirty four of these samples were tested for possible use as clay body ingredients, while sixty five samples were selected for assessment as glaze ingredients. A wood fired kiln was built from firebricks produced from a local deposit of a white bauxite related material. Materials selected as a result of these tests were combined to create ceramic objects fired at stoneware temperatures. The most interesting result of the investigation was the discovery of a number of small weathered dykes and sills, samples from which were developed into workable ceramic clay bodies and glazes using a simple empirical testing procedure. A previously unknown excellent white translucent native porcelain stone or ‘bai tunze’ was discovered and developed into a workable porcelain body. Some iron stained porcelain bodies that ‘flashed’ red in the wood firing kiln were also developed. Exhibitions of the creative work produced were shown in the ‘Legge Gallery’, a Fine Art gallery in Sydney. Two critical reviews of those shows appeared in the magazine Craft Arts International, No. 64, 2005, pp 106-107 and The Journal of Australian Ceramics, Vol 46 #1 pp 21-24. Several papers were published detailing various aspects of the research: “The Search for Raw Materials in the Southern Highlands” in The Journal of Australian Ceramics, Vol 41#3, pp 22-23; “Flotation – A method of refining useful minerals”, in The Journal of Australian Ceramics, Vol 41#3, pp 24-25; “Magic Dirt” in The Journal of Australian Ceramics, Vol 46 #1 pp 76-79; “New work from an old landscape”, in Ceramics Technical, 24, 2007. pp 45-52;“From the ground up”, in Ceramic review, issue 222, 2006, pp 54-55. The research concludes that the Southern Highlands of New South Wales is geologically rich in suitable materials for the production of stoneware ceramics and that there are a few specific bai tunze like materials that are very interesting and have considerable aesthetic potential. The research determined that these bai tunze like materials are potentially capable of being developed into clay bodies and glazes of great beauty. / Doctor of Philosophy (PhD)

An investigation of the geological resources of the Southern Highlands was undertaken and over two hundred samples were collected and examined for possible use as stoneware ceramic ingredients. Thirty four of these samples were tested for possible use as clay body ingredients, while sixty five samples were selected for assessment as glaze ingredients. A wood fired kiln was built from firebricks produced from a local deposit of a white bauxite related material. Materials selected as a result of these tests were combined to create ceramic objects fired at stoneware temperatures. The most interesting result of the investigation was the discovery of a number of small weathered dykes and sills, samples from which were developed into workable ceramic clay bodies and glazes using a simple empirical testing procedure. A previously unknown excellent white translucent native porcelain stone or ‘bai tunze’ was discovered and developed into a workable porcelain body. Some iron stained porcelain bodies that ‘flashed’ red in the wood firing kiln were also developed. Exhibitions of the creative work produced were shown in the ‘Legge Gallery’, a Fine Art gallery in Sydney. Two critical reviews of those shows appeared in the magazine Craft Arts International, No. 64, 2005, pp 106-107 and The Journal of Australian Ceramics, Vol 46 #1 pp 21-24. Several papers were published detailing various aspects of the research: “The Search for Raw Materials in the Southern Highlands” in The Journal of Australian Ceramics, Vol 41#3, pp 22-23; “Flotation – A method of refining useful minerals”, in The Journal of Australian Ceramics, Vol 41#3, pp 24-25; “Magic Dirt” in The Journal of Australian Ceramics, Vol 46 #1 pp 76-79; “New work from an old landscape”, in Ceramics Technical, 24, 2007. pp 45-52;“From the ground up”, in Ceramic review, issue 222, 2006, pp 54-55. The research concludes that the Southern Highlands of New South Wales is geologically rich in suitable materials for the production of stoneware ceramics and that there are a few specific bai tunze like materials that are very interesting and have considerable aesthetic potential. The research determined that these bai tunze like materials are potentially capable of being developed into clay bodies and glazes of great beauty. / Doctor of Philosophy (PhD)

Over many years, researchers in the field of flotation have developed an in-depth understanding of processes occurring in the pulp phase of flotation machines. Until recently, however, the froth phase has received little attention. The froth phase serves to separate bubble-particle aggregates from suspended slurry in a flotation cell. The mechanism of recovery by entrainment, its relationship to water recovery and particle size dependency is well understood. Froth recovery, (the fraction of particles entering the concentrate launder that entered the froth phase attached to air bubbles), is not well understood. Up until now, there has been doubt over whether this property is dependent on particle size and hydrophobicity. Difficulties in measuring froth recovery had previously prevented researchers from gaining a deeper understanding of the transport of attached particles across the froth phase. A novel device was designed and tested to measure froth recovery by isolating bubble-particle aggregates in the pulp-phase of flotation machines through the determination of the bubble loading in the pulp phase (mass of particles attached per unit volume of air bubbles). This technique can be used with other measurements to investigate froth selectivity by directly comparing these captured particles to those found in the froth phase. Evidence was collected at Red Dog Mine, Alaska and Newmont Golden Grove Operations, Western Australia which showed that the froth phase selectively transported more hydrophobic and smaller sized particles across the froth than less hydrophobic and larger particles. Particles collected in the device were compared to those found in the concentrate stream on a size by mineral by liberation class. Froth recovery was also calculated on a size by mineral by liberation class for two valuable sulphide minerals in a continuous 3m³ flotation cell. These results show that the froth phase is responsible for the upgrading of attached particles across the froth phase as well as for the separation of bubble-particle aggregates from suspended slurry. The pulp phase is responsible for creating bubble-particle aggregates through the attachment of hdyrophobic mineral particles to air bubbles. Many complex factors affect the extent to which this occurs including the size and hdyrophobicity of the particles, the size and number of air bubbles produced by the flotation machine, the rate of collisions between particles and bubbles and the overall chemistry of the system. This measurement of bubble loading presents an opportunity to measure the impact of all these factors on the successful creation of bubble-particle aggregates. Based on a literature review suggesting that there was a high probability of particles being detached at the pulp-froth interface due to the aggregates change in momentum, a three phase description of a flotation cell was proposed. The three phases were: pulp, pulp-froth interface and upper froth zones. A second froth recovery measurement technique (changing froth depth) was used in combination with the bubble load technique to determine the recovery across each of the two froth zones. It was found that the pulp-froth interface appears to be responsible for the selectivity observed across the froth phase as a whole. These findings will enable more in-depth research into the sub-process of the froth phase as well as assisting flotation cell design through a better understanding of the roles of the pulp-froth interface and the upper froth region.

This thesis presents ab-initio quantum mechanical calculations at the density functional theory (DFT) level on defect centers hosted by crystalline systems of geologic importance (i.e. fluorite, quartz, stishovite). The research brings new, complementary data to the current understanding of defect structures in minerals and explores the advantages of a theoretical approach in the field of mineral spectroscopy. This present research presents the first ab-initio calculations of the O23- type defects in crystalline solids. New data on the electronic properties and structural characteristics of O23--Y3+ defect in fluorite-type structures (CaF2 and SrF2) were obtained at the DFT level. These results confirm the stability and the molecular character of the O23--Y3+ center, revealing a spin density that is equally distributed between the two oxygen atoms. Our results report an O-O bond distance of 2.47 Å in CaF2 and 2.57 Å in SrF2. The calculated 17O and 19F hyperfine constants for of the O23--Y3+ center are in good agreement with their corresponding experimental values reported by previous electron paramagnetic resonance (EPR) and electron nuclear double resonance (ENDOR) studies, while discrepancies are notable for the 89Y hyperfine constants and are probably attributable to an inadequate basis set for Y.<p> The present study provides a more complete picture of the coupled Al-M substitution for Si in quartz, while investigating the characteristics and electronic properties of the diamagnetic [AlO4/M+]0 (where M = H, Li, Na and K) defects. The diamagnetic [AlO4/M+(a<)]0 defects with M = H, Li and Na have been shown to be more stable than their [AlO4/M+(a>)]0 structural analogues (where a> and a< denote the location of the charge compensating ion on the long-bond and short-bond side, respectively), correctly predicting the common occurrence of paramagnetic [AlO4/M+(a>)]+ centers. The present study confirms previous suggestions that incorporation of the [AlO4/M+]0 defects results in significant structural relaxations that extend at least to the nearest Si atoms. The [AlO4/K+]0 defects have been investigated for the first time and are shown to be stable in quartz. The results of this study have implications for the uptake of Al in quartz.<p> The present research evaluates the structural models of [AlO4/Li] paramagnetic defects in α-quartz. The results confirm the previous experimental findings and propose an additional paramagnetic defect [AlO4/Li+(csmall)]+, with the unpaired electron located on a short-bonded O atom and the Li compensator just off the edge of the small channel. Accordingly we suggest that three distinct Al-Li paramagnetic defects can be can be found in quartz, two of them having the hole located on a short-bonded O and one trapping the hole on a long-bonded O atom. However the structural similarities with the [AlO4/Li+(a>)]+ defect would require detection and measurement of the 17O hyperfine structure for an unequivocal EPR identification.<p> The present work also reports on first-principles quantum-mechanical calculations on the previously proposed [O23--Al3+] defect in stishovite. Our results show that the unpaired spin is 85% localised on one of the six oxygen atoms at an AlO6 octahedron, while the calculated 27Al hyperfine constants are similar to those determined by EPR experiments. Accordingly we propose the Al center to represent an [AlO6]0 defect, and hole hoping among equivalent oxygen atoms is responsible for its detection only at cryogenic temperatures. Theoretical calculations also show that diamagnetic precursors [AlO6/H+]0, [AlO6/Li+]0 and [AlO6/Na+]0 are stable in stishovite. The calculated OH bond distance and orientation are in excellent agreement with those inferred from FTIR spectra and previous theoretical calculations. The calculated [AlO6/Li+]0 and [AlO6/Na+]0 defects suggest that monovalent cations such as Li+ and Na+ are potentially important in accommodating Al in stishovite in the lower mantle.

Graduation date: 1992

This thesis described the results of two studies that measured the concentrations of serum micronutrients in western Canadian beef cows at key production points, and examined associations between reproductive outcomes and micronutrient concentrations. The first study reported the serum copper and molybdenum concentrations at pregnancy testing time in cows from 66 cow-calf herds that were enrolled in a study of factors affecting productivity in 205 herds from western Canada. A relatively small proportion of cows had serum copper and molybdenum concentrations outside of adequate levels (16.2% of cows had below adequate serum copper, < 0.60 ppm; 12% of cows had high serum molybdenum, > 0.10 ppm). There were no associations between copper and molybdenum concentrations measured at the end of the grazing season and reproductive outcomes measured in these cows, with the exception that cows with the lowest serum copper concentrations at pregnancy testing were more likely to be pregnant than cows with higher copper concentrations. The practice of comparing serum copper and molybdenum concentrations between pregnant and non-pregnant animals in the fall as a tool in investigating poor pregnancy rates was not supported by this study. In the second study, serum micronutrient concentrations of beef cows (n = 791) in southern Saskatchewan were measured before placement onto summer grazing and breeding pastures and again at the end of the grazing season. Pre-breeding serum copper concentrations were less than adequate (< 0.60 ppm) in 75% of cows. High concentrations of serum molybdenum (d 0.10 ppm) were present in 19% of cows at pre-breeding. Cows < 10 years of age with lower pre-breeding serum copper concentrations were at increased odds of nonpregnancy. The greatest effect on pregnancy rates was observed for pre-breeding serum copper concentrations < 0.4 ppm. Season of measurement influenced the concentrations of serum micronutrients in these cows. Copper and vitamins A and E were higher in the fall, and molybdenum and selenium concentrations were lower in the fall. These studies described serum micronutrient concentrations from healthy cows in western Canada at two production points, pre-breeding placement onto grazing pastures and pregnancy testing when cows are removed from grazing pasture. Identifying increased odds of nonpregnancy in cows with below adequate serum copper at pre-breeding emphasizes the importance of ensuring adequate copper concentrations in breeding females during this critical production phase.