Graduation date: 1979 / Best scan available for tables. Original is a black and white photocopy.

No description available.

Thesis (M.S.)--Oregon State University, 2000. / Typescript (photocopy). Includes bibliographical references (leaves 139-148). Also available on the World Wide Web.

Transition metal and rare earth element (REE) data are presented for various sedimentary materials from two Manganese Nodule Program (MANOP) sites in the eastern tropical Pacific. These data constrain the sources of elemental supply to the seafloor and the processes that control ferromanganese nodule genesis. Investigation of elemental partitioning between suspended particles, sediments, ferromanganese nodules, crusts, and micronodules indicates that particle settling dominates REE supply to the seafloor at MANOP site H. Partitioning of the particle flux reveals that although detrital and labile particles both convey REE to H sediments and nodules, labile biogenic debris is the primary source of REE accreted by site H nodules. Evidence from REE abundance patterns and correlations of REE with other elements define three basic processes of nodule accretion: (1) hydrogenous or direct seawater precipitation; (2) oxic diagenesis, referring to a variety of ferromanganese accretion processes which occur in oxic sediments; and (3) suboxic diagenesis, in which Mn is mobilized by the oxidation of sedimentary organic matter. The REE geochemistry of site H nodules suggests an additional accretionary process, resulting from the degradation of labile organic matter in an oxic environment. Contrasts in REE patterns, major element compositions, and fluxes of various elements in sedimentary samples from MANOP site H (a nodule-bearing site) with site M (a nodule-free site) reveal differences in the sources of material to the seafloor in the two environments. Geochemical data imply a greater hydrothermal influence and a greater accumulation of organic carbon in site M sediments relative to those at site H. Comparisons of the REE and major element geochemistry of H and M sediment traps, sediments, and crusts, as well as nodules from site H, imply that the reductive mobilization of Mn and geochemically similar elements is controlled primarily by surface water biological productivity and the accumulation of organic carbon in the sediments. The organic flux to the sediments determines the degree of depletion of oxidants, which governs the reduction, mobilization, and supply of metals to nodule surfaces. It appears that the depth to the Mn redox boundary and possibly seasonal variations in the flux of organic material to the seafloor determine whether nodules grow or whether Mn is exported to bottom waters. / Graduation date: 1985

No description available.

Thesis (Ph. D.)--University of Wisconsin--Madison, 1975. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.

M.Sc. (Biochemistry) / Manganese (Mn) is an essential trace element. Although it is vital for the normal development of mammals, too much Mn can be harmful. Most reported cases of toxicity have been found in occupational settings, such as welding, mining and ferro-manganese (FeMn) production plants. Long-term overexposure to Mn can result in lung epithelial necrosis and the development of a neurological disease, manganism. Even though evidence of Mn-associated diseases exists, some epidemiological studies have found no association between occupational exposure levels and possible indicators of neurotoxic effects. It is, therefore, important to establish Mn toxicity and the mechanisms involved in this toxicity, for a possible identification of biomarkers of exposure and effect. The hypothesis formulated states that, FeMn particulate matter consists of nano and micro sized particles that, upon inhalation, may cause injury to the lungs and translocate to the brain. Since Mn-induced injury to the brain and lungs is a possibility, this study aimed to investigate the effects of FeMn dust, which was collected from a FeMn smelter works, on primary rat astrocytes and human bronchial epithelial (BEAS-2B) cells. This was achieved by first characterizing the physicochemical properties of the particles by using a scanning mobility particle sizer (SMPS) and aerodynamic particle sizer (APS) for size distribution, Brunauer-Emmett-Teller (BET) for surface area determination and inductively coupled plasma atomic emission spectroscopy (ICP-AES) for elemental composition analysis. Cells were treated with 5, 10, 25 μg/cm2 FeMn, and particle uptake, by astrocytes and BEAS-2B cells, was confirmed using dark field microscopy e.g. Cytoviva® hyperspectral imaging system. The viability and toxicity of FeMn was studied using the conventional toxicity assay systems, including 3-bis [2-Methoxy-4- nitro-5-sulfophenyl]-2H-tetrazolium-5-carboxyanilide salt (XTT), adenosine triphosphate (ATP) and lactate dehydrogenase (LDH) assays. It was, however, established that FeMn particles interfere with the final read-out produced by some of these assay systems. Therefore, a rare application of the xCELLigence real time cell analysis (RTCA) system was implemented, as a better option, in the assessment of the toxicity and viability of cells in the presence of FeMn particles. The ability of FeMn particles to cause deoxyribonucleic acid (DNA) damage in both cell types was also determined using the alkaline comet assay. Finally, the nuclear translocation of the antioxidant transcription factor nuclear factor erythroid 2-related factor 2 (Nrf2) and inflammatory transcription factor nuclear factor kappa B (Nf-κB), was studied using Western blotting. The results showed that FeMn, in a dose dependent manner, could enter the cell, decrease the viability, induce DNA damage, and initiate nuclear transport of the studied transcription factors. The same methodologies were implemented to determine the physicochemical properties of Min- U-Sil 5 crystalline silica, used as a positive control, to assess its toxicity and effect on cellular viability. As well as its ability to induce DNA damage and initiate nuclear translocation of the two transcription factors, in astrocytes and BEAS-2B cells. Similar to FeMn particles, crystalline silica also enters the cells with subsequent reduction in cellular viability. It results in increased DNA damage and increased nuclear translocation of the studied transcription factors. The effects of crystalline silica on these cellular effects were, however, always higher than those produced by FeMn particles. To conclude, these results indicate that depending on the size distribution of particles in the work environment, they may enter different regions of the lungs. However, for those particles in the nano size region, direct access to the brain is a possibility. These results also indicate that after deposition in the target organ, these particles will produce cellular changes through oxidative stress. This would lead to inflammation, decreased cellular viability and increased toxicity.

Thesis-- University of Michigan, 1973.

Thesis (M.S.)--University of Wisconsin--Madison, 1984. / Typescript. eContent provider-neutral record in process. Description based on print version record. Bibliography: leaves 119-137.

Thesis (MScEng (Process Engineering))--University of Stellenbosch, 2009. / ENGLISH ABSTRACT: A project was initially commenced for optimising the production output at a specific high-carbon ferromanganese furnace. Since operational difficulties were experienced in this furnace and with a lack of reliable data for the year 2007, it was decided that data from a more stable high-carbon ferromanganese furnace should be analysed instead. Three key performance indicators (KPI’s) were selected to give an indication of overall process performance. These were: (1) the total tonnes of high-carbon ferromanganese produced per tonne of feed material, (2) the percentage recovery of manganese to the alloy product, and (3) the alloy:slag ratio. Maximisation of each of these would contribute to the overall improvement of the process. To achieve the objectives of the project, a hybrid model was developed to characterise the production behaviour of the furnace and to optimise the proposed KPI’s. The hybrid model consisted of two modelling branches, viz. equilibrium and dynamic modelling. An equilibrium sub-model was created and the output results were then used as inputs into a dynamic sub-model, which not only considered the effects of thermo-equilibrium interactions, but also the faster-changing electrical dynamics of furnace control. The final modelling step involved genetic optimisation, whereby model variables were manipulated to optimise the proposed KPI’s. In other words, operating conditions were established to improve furnace performance. It was determined that significant improvement in the values of the KPI’s may be expected if the optimised setpoints are implemented on-site. The existing setpoints for electrical operation should be maintained while the power expended per tonne of alloy should be altered (by tapping more regularly). Specific adjustments to the proportions of the feed recipe should also be made. / AFRIKAANSE OPSOMMING: ‘n Projek is aanvanklik begin om die produksieproses by ‘n spesifieke hoëkoolstof ferromangaanoond te optimiseer. Sedert operasionele probleme ondervind is in die oond en daar ‘n tekort is aan vertroubare data vir die jaar 2007, is daar besluit om data van ‘n meer stabiele hoëkoolstof ferromangaanoond te annaliseer. Drie sleutelverrigtingsaanwysers (SVA’s) is geselekteer om die algehele prosesverrigting aan te dui. Hulle is: (1) Die totale tonnemaat hoëkoolstof ferromangaan geproduseer per tonnemaat van voermateriaal, (2) die persentasie herwinning van mangaan tot die allooiproduk, en (3) die allooi:slak verhouding. Die verhoging van elk van die bogenoemde sal bydra tot die algehele bevordering van die proses. Om die doelwitte van die projek na te kom, is ‘n Kombinasiemodel ontwikkel om die produksie gedrag van die oond te karakteriseer en om die voorgestelde SVA’s te optimiseer. Die Kombinasiemodel het bestaan uit twee modelleringsvertakkings, nl. termodinamiese ewewig en dinamiese modellering. ‘n Termodinamiese ewewig submodel is geskep en die uitset resultate is gevolglik gebruik as invoerdata na ‘n dinamiese sub-model, wat nie slegs die uitwerking van termo-ewewiginteraksies in ag neem nie, maar ook die vinnigveranderende elektriese dinamika van die oond. Die finale modelleringstap het genetiese optimisering behels, waarby model veranderlikes gemanipuleer is om die voorgestelde SVA’s te optimiseer. Met ander woorde, operasionele kondisies is vasgestel om oond produksie te bevorder. Dit is bepaal dat kenmerkende verbetering in die waardes van die SVA’s verwag kan word as die ge-optimiseerde setpunte toegepas is op die oond. Die oorspronklike setpunte vir elektriese beheer hoort gehandhaaf te word terwyl die krag verbruik per ton allooi verander moet word (deur om meer gereeld te tap). Spesifieke verstellings op die proporsies van die voerresep moet ook gemaak word.