No description available.

Fungi are the primary decomposers of recalcitrant plant and animal material in terrestrial environments, thereby serving as important drivers of global carbon cycling and climate dynamics and as mediators in renewable energy production. Degradation of organic litter is achieved through secretion of a large and diverse suite of extracellular enzymes and reactive metabolites, collectively referred to as the secretome. This thesis explores the secretomes of four filamentous Ascomycete fungi that were recently isolated from field sites and have the ability to oxidize manganese (Mn)(II) to Mn(III/IV) oxides: Alternaria alternata SRc1lrK2f, Stagonospora sp. SRC1lsM3a, Pyrenochaeta sp. DS3sAY3a, and Paraconiothyrium sporulosum AP3s5-JAC2a. Mn(II)-oxidizing fungi are of engineering and industrial interest due to their utility in the remediation of metal-contaminated waters and their ability to harness Mn(II) oxidation in the breakdown of lignocellulosic plant material. While the processes of Mn(II) oxidation and carbon oxidation are mediated by the secretome in white-rot Basidiomycete fungi, comparatively little is known about the oxidative capacity of the secretomes of Ascomycetes, particularly those of environmental isolates. Using a combination of microscopy and chemical assays, this thesis identifies extracellular superoxide as the oxidant of Mn(II) in Stagonospora sp. and Pyrenochaeta sp. during growth on solid substrate and suggests a role for secreted organic polymers in Mn(III) complexation and Mn oxide templation. Furthermore, through in-gel assays and bulk mass spectrometry, this work demonstrates that species-specific secreted enzymes confer Mn(II) oxidative capacity in the liquid, cell-free secretome of these two fungi and P. sporulosum and shows that Mn(II) oxidative capacity changes over time in a pattern unique to each organism. Through quantitative iTRAQ proteomics and custom bioinformatic analyses, the protein composition of the secretomes of all four filamentous Ascomycetes was fully characterized, revealing a rich and functionally diverse suite of extracellular enzymes that suggest the ability to oxidize carbon through both direct and indirect mechanisms. Although the functional diversity of the secretome was similar among the four organisms, the fungi exhibited striking differences in regulation of carbon-degrading enzymes over a three-week time course, illustrating species-specific and temporal shifts in carbon utilization strategies among the phylogenetically diverse species. Taken together, results of this thesis further our understanding of the mechanisms of Mn(II) oxidation by fungi, demonstrate the rich functional diversity and oxidative capacity of Ascomycete secretomes, and enhance our understanding of the role of filamentous Ascomycetes in recalcitrant carbon turnover in the environment. / Engineering and Applied Sciences - Engineering Sciences

No description available.

Seventy-five synthetic powder trioctahedral mica samples (between Mg, Co, Ni, and Fe end members, with different degrees of oxidation, vacancy and Al/Si contents, and including an OH/F substitution series) were studied by room-temperature powder X-ray diffraction. The iron-bearing samples were studied by 57Fe Mossbauer spectroscopy. Subsets of the samples were also characterized by scanning electron microscopy combined with energy dispersive spectroscopy, optical microscopy, X-ray fluorescence spectroscopy, and gas chromatography. Lattice parameters (refined under the 1M stacking polytype, space group C2/m) were determined for all powder samples and iron site populations ([4]Fe 3+, [6]Fe2+, and [6]Fe 2+) were obtained from Mossbauer spectroscopy. The relation (c/a)cosbeta* = 113 was found to hold exactly (within experimental error) for all synthetic powders whereas it does not hold in general for synthetic and natural 1M single-crystals. The above relation is predicted to hold for geometric home-octahedral sheets (having equal M1 and M2 site bond lengths) and not to hold for geometric meso-octahedral sheets (having unequal M1 and M2 site bond lengths). The counter-rotation of the M2 site of 1M single-crystals exactly (within experimental error) follows the geometric meso-octahedral sheet model, which, assuming a uniform octahedral sheet height and site-specific M1 and M2 bond lengths, predicts site-specific flattening angles and a counter-rotation angle for the M2 site which is uniquely determined by the bond length difference between the M1 and M2 sites. A geometric meso-octahedral 2:1 layer silicate was shown to require corrugated tetrahedral sheets composed of bond-distorted tetrahedra. Key geometric meso-octahedral distortions in 1M single-crystals were identified and elucidated: (i) intra-layer top-bottom displacements within a TOT layer; and (ii) a tetrahedral bending angle between the apical bond and the pyramidal base formed by the three basal bonds. Plots of lattice parameter b versus average-octahedral-bond-length allowed the following distinction to be made: Unoxidized divalent synthetic solid solution series tend to evolve along constant flattening-angle lines whereas trivalent octahedral cation and vacancy bearing natural single-crystals and synthetic powders follow trends with varying flattening angles. We found that the bond length of a given interlayer cationic species monotonously increases as the tetrahedral rotation angle alpha decreases in trioctahedral-1 M single-crystals. An upper limit of tetrahedral rotation of alpha = 9.5° was demonstrated to occur in trioctahedral-1M K-rich micas having an <AlSi3> sheet, for both synthetic powders and natural single-crystals. Other attempts at applying geometric crystal chemical models and at identifying structure-chemical relationships from structural refinement data will benefit from the perspective of our more complete and systematic approach based on pursuing simple geometrical models using 'regular' coordination polyhedrons and characteristic cation-specific bond lengths up to the limit beyond which such models are shown to necessarily breakdown because of unavoidable 'non-regular' polyhedral distortions. (Abstract shortened by UMI.)

The main features of a syenitic complex located near Kamloops B.C. are described. The most noteworthy of these is the abundance of andradite garnet in the rocks. The mineral is believed to have crystallized from a melt that had the composition of quartz syenite. The melt, prior to its consolidation, intruded and apparently assimilated limestone. This caused the rocks to be differentiated at or near their present site by the crystallization of calcium silicates such as the andradite garnet. Quartz -rich rocks were produced first and ultimately nepheline -bearing ones. / Science, Faculty of / Earth, Ocean and Atmospheric Sciences, Department of / Graduate

Twenty-one galena specimens from 16 mineral deposits in the Kootenay district analysed isotopically in replicate have a linear relationship of isotopic compositions on a Pb²º⁶/Pb²º⁴ versus Pb²º⁷/Pb²º⁴ graph. Twelve of the galenas, including two from Sullivan mine (East Kootenay district), were analysed by an intercomparison technique; the first application of the intercomparison method to an anomalous lead suite. Intercomparison results verify the linear compositional pattern (slope = 0.1084 ± 0.0033). These results indicate that: 1. Kootenay arc leads are multi-stage leads. 2. Sullivan-type lead is the parent common lead from which the anomalous suite developed. 3. Kootenay arc mineral deposits formed during one major mineralizing episode. Time of anomalous lead mineralization, tm, is probably Jurassic as deduced from potassium-argon dates and crosscutting relations of ores and igneous rocks. Assuming tm = 180 m.y. time of emplacement of uranium and thorium that produced the radiogenic component of the anomalous leads is approximately 1700 m.y., possibly the age of Lower Purcell strata of the East Kootenay district. Lead isotopic compositions show no obvious correlations with age of wallrock, type of wallrock, geological nature of ore deposits, or minor element content of galena. Post-ore thermal metamorphism and hydrothermal alteration do not appear to have changed lead isotopic compositions. The history of evolution of Kootenay arc anomalous leads is interpreted as follows: 1. Formation of source rocks containing uranium and thorium about 1700 m.y. ago. 2. Introduction of Sullivan-type lead into source rocks about 1340 m.y. ago. 3. Mixing of Sullivan-type lead with radiogenic lead formed by decay of uranium and thorium, and transportation and deposition of these "lead mixtures” to form anomalous lead deposits during Coast Range orogeny. Geologic and isotopic data from Sullivan mine are reconciled most easily with an epigenetic origin of the Sullivan orebody, and probably with a genetic relation of Sullivan ore fluids with the source magma of Moyie Intrusions. Holmes-Houtermans model age for Sullivan ore, based on intercomparison data, is 1340 m.y. Sullivan lead evolved in a source with U²³⁸/Pb²º⁴ = 9.02, Th²³²/Pb²º⁴ = 36.71, and Th/U = 4.07 (in terms of present day abundances). A method of estimating volume of source rock of anomalous lead deposits is outlined. Calculations for Jersey, Reeves Macdonald and Bluebell mines indicate that the radiogenic lead component of these deposits could have been derived from 1 to 10 cubic kilometers of source rock containing 3 ppm uranium (and approximately 12 ppm Th) if only one-third to one-half of the radiogenic lead in the source were extracted during a period of concentration and mineralization. Kootenay arc deposits can be divided into two classes on the basis of minor element contents of galenas. This division closely corresponds to the following geological types of deposits: 1. replacement deposits with no evidence of open space filling, and 2. deposits with evidence of open space filling and variable amounts of wallrock replacement. Minor element contents of galenas from Salmo-type replacement deposits suggest but do not prove a fairly low temperature of mineral deposition. / Science, Faculty of / Earth, Ocean and Atmospheric Sciences, Department of / Graduate

Mineralization at Galore Creek consists mainly of disseminated chalcopyrite, bornite and pyrite. Biotite and orthoclase are the dominant alteration minerals with commonly associated anhydrite, garnet, apatite, calcite and magnetite. The mineralization occurs in altered syenites, metavolcanics and brecciated equivalents of these along the contacts of a complex of syenite porphyries which display many characteristics of epizonal intrusions. Exsolution textures of bornite and chalcopyrite indicate a minimum temperature of deposition of 475°C. This leads to the conclusion that the deposit formed at a relatively high temperature and a shallow depth and therefore may be classified as xenothermal. / Science, Faculty of / Earth, Ocean and Atmospheric Sciences, Department of / Graduate

A project report submitted to the faculty of Engineering, University of the Witwatersrand, in partial fulfilment of requirement of Master of Science in Engineering Johannesburg, 1992 / The optimal depletion of a mineral deposit involves the optimisation of all the proccesses involved in the mining operation. [Abbreviated Abstract. Open document to view full version] / MT2017

No description available.

No description available.