A imobilização da MeP em suportes inorgânicos permite isolar o sítio de reação prevenindo a dimerização e/ou auto-destruição oxidativa da mesma, constituindo-se num catalisador biomimético. Neste projeto foi objetivo avaliar o comportamento biomimético de manganês porfirinas, comparando sistemas imobilizadas de diferentes maneiras em sílica funcionalizada em processos de oxigenação do cicloocteno ecicloexano, incluindo metabolismo de um fármaco. A primeira etapa do projeto consistiu na obtenção dos sistemas catalíticos contendo metaloporfirinas imobilizadas em sílicas modificadas. Para isso foi sintetizada a M(4-N-Py)TFPPH2 base livre, seguida da inserção de manganês (III) e metilação obtendo-se o catalisador Mn[{M(4-N-MePy)TFPP}]2+. Foi inserido manganês também nas porifinas base livre [T(4-N-MePy)P]Cl4 e [TFPP]H2 obtidas comercialmente obtendo-se os catalisadores Mn[T(4-N-MePy)P]5+ e Mn[TFPP]+. Realizou-se a funcionalização da sílica gel com (i) grupos sulfonatofenil e propilimidazol (SiSO3-IPG); (ii) grupos 3-aminopropil (APTES); (ii) grupos 3-(2-(2-aminoetilamino) etilamino) propil (AP(EA)2TS) e (iv) cloropropil e 1,6-diaminoexano (DA1,6Si). Essas sílicas foram imobilizadas nas manganêsporfirinas através de interações eletrostáticas ou via ligação covalente. Esses catalisadores foram usados na oxigenação de (Z)-cicloocteno e cicloexano e no estudo de metabolismo oxidativo do fármaco praziquantel (agente anti-helmíntico). Os catalisadores [Mn(TFPP)]- APTES, [Mn(TFPP)]- AP(EA)2TS, [Mn{M(4-N-MePy)TFPP}]-SiSO3, [Mn{M(4-N-MePy)TFPP}]- SiSO3(IPG), [Mn{M(4-N-MePy)TFPP}]-APTES, [Mn{M(4-N-MePy)TFPP}]- AP(EA)2TS, [Mn{M(4-N-MePy)TFPP}]- DA1,6Si foram usados em reações de epoxidação do (Z)-cicloocteno pelo PhIO e os resultados obtidos foram baixos. Já com H2O2 como oxidantes os resultados foram muito bons quando foi adicionado imidazol. Nas reações de hidroxilação do cicloexano os rendimentos obtidos foram altos quando a MnP foi imobilizada por interação eletrostática. Neste sistema as oxidações competitivas são minimizadas. Os sistemas com melhores resultados foram selecionados para estudos com o praziquantel (PZQ). Diferentemente dos resultados obtidos previamente com FeP, os sistemas com MnPs se revelaram bons catalisadores biomiméticos, uma vez que apresentaram quantidades expressivas do metabólito trans-4\'-OH, o principal metabólito produzido in vivo. As MnPs, em particular as piridis substituídas apresentaram boa conversão de PZQ sendo [Mn{T(4-N-MePy)P}]-SiSO3 o melhor, além de produzir 38 % do trans-4\'-OH, apresentou 87 % de conversão. Estes resultados preliminares indicam um sistema muito promissor com resultados inéditos. / The immobilization of metalloporphyrins in inorganic supports allows to isolate reaction site preventing dimerization and/or catalyst oxidative selfdestruction constituting in a biomimetic system. In this project the aim was evaluate the biomimetic behaviour of manganese porphyrins, comparing systems immobilized on sílica in different ways in oxygenations processes of (Z)- cyclooctene and cyclohexane, including a study of drug metabolism. Initially the catalytic systems containing metaloporphyrins immobilized on modified silica were obtained. The free base M(4-N-Py)TFPPH2 was firstly synthesized, then the MnIII was inserted, methylated obtaining the catalyst Mn[{M(4-N-MePy)TFPP}]2+. The MnIII also was inserted in the commercials free base [T(4-N-MePy)P]Cl4 e [TFPP]H2 obtaining the catalysts Mn[T(4-N-MePy)P]5+ e Mn[TFPP]+. The sílica gel were functionalizated with (i) sulfonatephenyl and propylimidazole groups (SiSO3-IPG); (ii) 3-aminopropil groups (APTES); (ii) 3-(2- (2-aminoethyilamine) ethilamine) propyl groups (AP(EA)2TS) and (iv) chloropropyl e 1,6-diaminehexane (DA1,6Si). Manganese porphyrins were immobilized on these sílica supports through electrostatic interactions or covalent bond. These catalysts were used in the (Z)-ciclooctene and cyclohexane oxigenationand in the oxidative metabolism of praziquantel (antihelmintic agent). 13 The catalysts [Mn(TFPP)]- APTES, [Mn(TFPP)]- AP(EA)2TS, [Mn{M(4-NMePy) TFPP}]-SiSO3, [Mn{M(4-N-MePy)TFPP}]- SiSO3(IPG), [Mn{M(4-NMePy) TFPP}]-APTES, [Mn{M(4-N-MePy)TFPP}]- AP(EA)2TS, [Mn{M(4-NMePy) TFPP}]- DA1,6Si were used in (Z)-ciclooctene epoxidation rendering low yields using PhIO as oxidant, contrasting the good yields when imidazole and H2O2 as oxidant were used. In the hydroxylation of cyclohexane the yields were high when the MnP were immobilized through electrostatic interaction. In this system the competitive oxidations are minimized. The best systems were selected for to study the praziquantel oxidation. Differently from FeP results previously obtained, the MnP systems revealed good biomimetic catalysts for PZQ, since high amount of trans-4\'-OH metabolite was obtained, the principal in vivo metabolites. The pyridil substituted MnP, particularly [Mn{T(4-N-MePy)P}]-SiSO3 showed the best results, besides the high yield of trans-4\'-OH (38%), the convertion attained 87%. These results are inedited and very promising biomimetic catalytic systems.

No description available.

A plug-type oxygen probe containing a magnesia stabilized solid zirconia electrolyte rod, was developed. This oxygen sensor was evaluated in the Fe-Cr-0 system at 1873 K by determining the Raoultian chromium and Henrian oxygen activities of an Fe-Cr alloy which was in equilibrium with pure Cr20 3 and a Cr20rsaturated liquid slag respectively. However, the slag reacted with the oxygen probe and therefore, a crucible assembly was developed to prevent direct contact between the slag and the oxygen sensor. The results obtained with this crucible assembly proved that no interaction between the oxygen probe and slag occurred and that the smaller slag/metal interface did not effect equilibrium between the slag and the metal. The Raoultian chromium activities of the Fe-Cr alloy containing 5 to 25% chromium determined in this study, deviate negatively from ideal Raoultian behaviour. The oxygen and chromium activities were used to determine the standard free energy change for the formation of solid Cr20 3 from the elements at 1873 K, and the value obtained is in good agreement with existing data. Evidently, the plug-type oxygen probes and the redesigned crucible assembly can be used to determine the oxygen activity of an Fe-Cr alloy, in equilibrium with a liquid slag at 1873 K, accurately and reliably. Therefore, these measurements were extended to the determination of the activity of MnO in (MgO-Si~-MnO)-slags. The chemical composition of the equilibrium phases pertaining in (Mg0-Si0Si02-MnO)slags saturated with (MnO-MgO) solid solutions and in contact with manganese metal, were determined by microprobe analyses. These results together with the known activity-composition relations of (MnO-MgO) solid solutions at 1873 K, were used to determine the activity of MnO in the slag. This method proved to be reliable and the MnO activities so obtained, could serve as a check for activities determined with the electrochemical technique. Furthermore, the same method could be used for the determination of the high temperature phase constitution of the slag when the oxygen potential of the slag/metal system is determined by electrochemical means. In the course of the determination of the oxygen potential of (MgO-SiOz-MnO)-slags at 1873 K by means of electrochemical oxygen probes, the magnesia stabilized zirconia solid electrolytes reacted with manganese metal and vapour which had a detrimental influence on the accuracy and reliability of the EMF (electromotive force) measurements. Accordingly, it was illustrated that zirconia solid electrolytes are not suitable for application in slag/metal systems containing manganese metal at 1873 K. Previous workers have shown that thoria solid electrolytes are not attacked by manganese metal at these high temperatures and should consequently be used with the crucible assembly developed in this study, for the determination of activities in (Mg0-Si02-Mn0)-slags at 1873 K. / Thesis (PhD)--University of Pretoria, 1991. / gm2014 / Materials Science and Metallurgical Engineering / Unrestricted

The Nsuta manganese deposit is located in the Western Region of Ghana, approximately five kilometers south of Tarkwa Goldfields. The deposit has been an important source of manganese ore since mining began in 1916. The purpose of this project was to produce a concise model of the stratigraphy, sedimentology and structural evolution of the deposit in support of future exploration projects. The manganese ores occur as an up to 45m thick carbonate bed in a thick turbidite-greenstone succession that is part of the ~2.2 Ga Birimian Supergroup. Calc-alkaline volcanics, volcaniclastics, turbidites, argillites and phyllites are thought to have been deposited in a backarc basin environment. The entire sedimentary succession, including the manganese orebody, is a thick turbidite package hosted between an upper and lower greenstone unit consisting predominantly of volcaniclastic material. The entire lithological succession at Nsuta is interpreted to have been deposited within the middle to lower reaches of a submarine fan environment. Field evidence suggests a simple stratigraphy, commencing with a lower greenstone unit composed largely of volcaniclastic material. This is followed by an upward-fining lower turbidite unit deposited in response to a marked transgression and sea level rise. Maximum rate of sea level rise provided ideal conditions for manganese precipitation and concentration, as detrital influx ceased. The central portion of the carbonate orebody that formed hosts the manganese orebody. An upward-coarsening turbidite unit follows above the carbonate unit. This upward-coarsening succession reflects a regression and a highstand systems tract in terms of sequence stratigraphic principles. It is capped by an unconformity that formed during a period of rapid relative sea level fall. It is overlain by a second upward-fining turbidite succession. This succession is not fully preserved as there is a sheared contact between it and the overlying upper greenstone unit. Post-depositional deformation and metamorphic alteration are largely attributed to the Paleoproterozoic Eburnean Orogeny. A first phase of compression was directed along a NW-SE axis and produced a series of isoclinal anticlines and synclines (F1) with NE-SW striking axial planes. This was followed by thrusting between the anticlines and synclines. The age of this deformation and closely associated greenschist metamorphism can be accurately constrained between 2.09 Ga and 2.07 Ga. E-W oriented oblique listric faulting has a prominent effect on the appearance of the Nsuta manganese deposit, as it produced a series of imbricate fault blocks dipping to the north. Associated with this period of deformation is small-scale cross folding with axes plunging to the east (F2). The faults post-date the Eburnean Orogeny and must be associated with a second major tectonic event. Finally, a NNE-SSW striking normal fault, locally known as the German Line, caused further block rotation, notably in the northern parts of the mining concession. Late Mesozoic deep lateritic weathering and incision of the lateritic peneplane by modern rivers have resulted in the complex dissected appearance of the Nsuta orebody. However, based on the detailed structural analysis provided in this study, a feasible target for future exploration of manganese ore buried beneath Late Mesozoic and Cenozoic sediments and soils, has been identified. This target is located to the west of Hills A and B. / Dr. J.M. Huizenga Prof. Nic Beukes Prof. J. Gutzmer

The aim of this project was to investigate the usage of manganese dioxide ore as a bio-filter media to remove metabolites in aquaculture closed system, and to determine whether manganese toxicity would at the same time represent a risk to fish. Initial work investigated the physical properties of manganese dioxide and its chemical interaction with ammonia and nitrite in the absence of biological activity. Subsequently, two pilot-scale pressurised filters were installed in a commercial scale hatchery in order to compare the metabolite removal performance of manganese dioxide against silicate sand in the presence of biological activity commonly found in aquaculture conditions. The investigation suggests that Mn medium is more reliable in converting ammonia to nitrate without producing a residual output of nitrite. The superior performance ofMn media compared with sand appears to be mainly related to the physical structure of the manganese ore. Furthermore, the Mn medium did not appear to be soluble in the ambient conditions normally found in aquaculture-closed system. From the design point of view, due to the higher ammonia and nitrite removal rates, a shorter retention time and a lower volume of media are required in the case of manganese dioxide technology compared with sand media. As a result, it is much easier to size a biofilter with Mn media. Manganese systems have a comparable total costs to conventional sand media, but using the Mn technology provides a more reliable control of toxic nitrite, thereby reducing risks offish loss and hence with reduced expected production costs.

Synthesis of new thio derivatised Pcs with manganese, titanium and vanadium as a central metal is reported. The complexes synthesised were characterised using spectroscopic and electrochemical means. The complexes displayed interesting spectroscopic properties with absorption of the Q band being observed in the near infrared region. These complexes have unusual colours for MPc complexes, with purple or red colour being observed in solution. Interesting electrochemical properties were observed, with rare observation of the MnIV/MnIII redox couple. There was observation of oxidation peaks for the pentylthio derivatised Pc with titanium as the central metal; this is unusual since for reported thio derivatives based on TiPc, no oxidation was observed. The vanadium based Pc showed an interesting spectrum for the first ring based reduction. The absorption spectrum obtained for the 1st reduction of the vanadium complex using spectroelectrochemistry would normally indicate a metal based process but comparing with literature it was concluded that it is a ring based reduction process. Generally all the MPc complexes formed a well ordered stable monolayer on the gold electrode. Electrocatalytic studies using L-cysteine revealed that the SAM based on manganese (III) octapentylthio phthalocyanine (AcOMnOPTPc) was the most effective since it catalyses L-cysteine at much lower oxidation potentials and it is also much more stable.

Interactions between manganese (Mn) deficiency and streptozotocin (STZ)-diabetes with respect to tissue antioxidant status were investigated in male, Sprague-Dawley rats. All rats were fed either a Mn-deficient (1 ppm) or a Mn-sufficient (45 ppm) diet for 8 weeks. Diabetes was then induced by tail-vein injection of STZ (60 mg/kg body weight), after which the rats were kept for an additional 4 to 8 weeks. The control groups comprised rats not injected with STZ, which were either Mn-deficient or Mn-sufficient. The Mn-deficient diet decreased the activities of manganese superoxide dismutase (MnSOD) in kidney and heart, and of copper-zinc superoxide dismutase (CuZnSOD) in kidney, in non-diabetic animals. In the diabetic rats, the Mn-deficient diet induced more pronounced decreases in activities of these same enzymes, and also increased liver MnSOD activity. Pancreas weights were significantly lower in Mn-deficient, compared to Mn-sufficient rats. Also, Mn-deficient, diabetic rats were significantly more hyperglycemic in response to a glucose load than Mn-sufficient, suggesting that they may have been more severely diabetic. Surprisingly, plasma and hepatic vitamin E levels increased progressively with the duration of diabetes. Lipid peroxidation, as measured by H₂O₂ -induced production of thiobarbituric acid reactive substances in erythrocytes, plasma lipoperoxides, and renal adipose tissue fluorescence, also increased concomitant with decreased liver and kidney glutathione levels. The effect of vitamin E-deficiency on Mn-deficient, diabetic rats was also investigated. Predictably, vitamin E-deficient rats were almost entirely depleted of plasma and liver vitamin E after 12 weeks on the deficient diets (4 weeks after STZ treatment). Consistent with this, tissue lipid peroxides were elevated compared to vitamin E-sufficient rats. Superimposing vitamin E-deficiency on manganese deficiency failed to add any further deficits in tissue antioxidant status. Higher glycosylated hemoglobin levels were observed in vitamin E-deficient, compared to vitamin E-sufficient, diabetic rats. These findings demonstrate for the first time an interactive effect between manganese deficiency and STZ-diabetes resulting in amplification of tissue antioxidant changes seen with either manganese deficiency or STZ-diabetes alone. This effect of cofactor deprivation in experimental diabetes raises the question of adequacy of the nominally Mn-sufficient diet in insulin-dependent diabetes mellitus. / Land and Food Systems, Faculty of / Graduate

A study was undertaken to determine the manganese status of some Lower Fraser Valley soils developed from alluvial and marine deposits. Mn fractions in six soils and in their particle size separates were determined by atomic absorption spectrophotometry. Water soluble Mn ranged from 0.5 to 1.4 ppm; Exchangeable Mn from 0.5 to 15.0 ppm; Hydroquinone reducible from 0.7 to 119.5 ppm; Total Mn from 82.0 to 957.5 ppm; and "Active Mn" from 3.2 to 129.8 ppm. These ranges were similar to reported values, except that.the study failed to find the high levels of total Mn reported by Baker on some soils from the same area. Generally water soluble and exchangeable Mn showed little variation within profile or between soils. In four out of the six profiles reducible and total Mn were higher in the parent material than in the surface horizons. However, there was no satisfactory fit for a number of the profiles to the four distribution patterns suggested by Leeper. Values for EDTA extractable and "active" Mn in two profiles suggest that both fractions of Mn represent the same chemical form. However, further results suggest that the two Mn fractions are different. In nearly all samples with high organic matter content EDTA extracted more Mn after removing "active Mn" than direct extraction with EDTA, supporting suggestions that EDTA extracts chelated Mn and also causes some dispersion of soil particles. Sonic dispersion led to increased recovery of all forms of Mn, more especially reducible and total Mn. The results suggest that until more is known about sonic dispersion it is unwise to assume that no modification of soil constituents takes place. Statistical techniques were used to examine the relationship between Mn distribution and parent materials, pH, organic matter content and cation exchange capacity. These analyses showed that the level of Mn fractions in the soil cannot be predicted by any single factor, but only by a number of soil factors in combination. The possibility of building up a computer model to predict Mn distribution is suggested. The significance of soil Mn distribution in terms of plant requirements is discussed. Plant available Mn in these soils, estimated by 0.02 M CaCl₂ extraction, ranged from 0.5 to 10.7 ppm. This was very similar to that for exchangeable. Based on data in the literature these soils were classified into manganese-deficient and-sufficient categories. Using extraction techniques only, various Mn pools were established for these soils according to the chemical pool concept proposed by Viets. These pools and their possible relation to Mn availability are discussed. It was suggested that a further study was necessary to establish a correlation between these Mn pools and plant Mn requirements and also to reveal the equilibria and rates of interconversion existing between the established pools as found under the soil conditions of the Lower Fraser Valley. / Land and Food Systems, Faculty of / Graduate

The Fraser Estuary was investigated five times under varying flow regimes. The surface distribution of dissolved manganese consistently exhibited a maximum value at a salinity ranging from 4 to 12 ppt. Experimental results and field data suggest this peak does not result from the desorption nor dissolution of riverborne suspended particulate manganese. The excess metal is derived from the estuarine bottom sediments. Desorption or dissolution of manganese from the estuarine bottom sediments resuspended due to the advancing salt wedge enhances the dissolved manganese concentration in the bottom waters, especially in the toe of the salt wedge. This manganese enrichment may also be influenced to a lesser extent by the concurrent release of some interstitial water with enriched dissolved manganese concentrations due to the in situ reduction of amorphous manganese oxides. The subsequent entrainment and mixing of water from the toe of the salt wedge into the outflowing river water causes a downstream increase in the dissolved manganese content, and eventually determines the peak manganese concentration and salinity. Further downstream mixing with saline waters having relatively low manganese levels causes surface concentrations to decrease. Thus, the dissolved manganese distribution can be explained in terms of two conservative dilution curves which intersect at the manganese peak. The dissolved oxygen generally behaves conservatively in both the surface and bottom waters of the Fraser Estuary. The removal of alkalinity may occur at low salinity, however, alkalinity exhibits conservative behaviour through most of the salinity range. The surface distribution of pH can be replicated theoretically only when mixing in the surface is considered as a two step process. The alkalinity behaves conservatively in the surface waters of the Strait of Georgia. The pH and dissolved oxygen display seasonal variations related to primary productivity and mixing processes. The distribution of dissolved manganese in surface waters of the Strait of Georgia is determined mainly by the dilution of Fraser River water. Bottom waters have enhanced dissolved manganese concentrations due to reductive remobi1ization of manganese from the sediments. Concentrations of dissolved manganese at mid-depths are determined by seasonal variations in the stability of the water column. Depth profiles of suspended particulate manganese indicate increasing concentrations with depth. This may result from the oxidative precipitation of manganese and/or the resuspension of bottom sediments. / Science, Faculty of / Earth, Ocean and Atmospheric Sciences, Department of / Graduate

M.Sc. / This dissertation describes the N1 manganese ore bed at Gloria Mine in the Kalahari Manganese Field, Northern Cape Province. It also compares the ore bed at Gloria Mine with the correlative bed further to the south at Mamatwan Mine. The ore bed at Gloria Mine can be subdivided into ten texturally distinct zones that are laterally consistent throughout the mine lease area. The mineralogy and geochemistry of the various lithostratigraphic zones are described from two drill cores (GL28 and GL24), situated away from any known structural features or unconformities that could have affected the properties of the Ore. The ore in drill core GL28 has a mineralogical composition similar to that of typical Mamatwan-type ore described at Mamatwan Mine with braunite and kutnahorite as the main minerals. However, in drill core GL24 the ore has a very different mineralogical composition although it is texturally and geochemically rather similar to Mamatwan-type ore. The ore is composed of hausmannite, calcite and jacobsite and is apparently related to a post-depositional alteration event that did not effect Mamatwan-type ore in the Mamatwan Mine area. This altered ore is similar in composition to low-grade leastaltered manganese ores in the cores of fault blocks at Wessels and N’Chwaning Mines i.e. the area known for its hydrothermally altered high-grade manganese ores in the northern part of the Kalahari Manganese Field. In addition to the above, the N1 manganese ore bed at Gloria Mine also underwent ferruginisation close to certain joints and normal faults. No obvious alteration could be detected where the ore bed is unconformably overlain by Dwyka diamictite, nor associated with a thrust fault displacing the ore.