Mineralogy and geochemistry of permian black shales and carbonate concretions in the lower ECCA formations of the Steytlerville- Jansenville area, southern Karoo basin
- Authors: Maake, Laurentias Tebatso
- Date: 2019
- Subjects: Black shales -- South Africa -- Jansenville , Geochemistry Chemistry, Analytic Mineralogy -- Analysis
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/40643 , vital:36206
- Description: The Lower Permian Ecca Group formations of the Karoo Basin of South Africa have recently been identified as a target for shale gas exploration. These units, named the Prince Albert, Whitehill and Collingham formations, comprise organic-rich shales with occasional associated carbonate deposits, and siliciclastic facies. Mineralogical and geochemical investigations were conducted into carbonaceous shales and associated sedimentary rocks in the Jansenville area of the southern Karoo Basin with the ultimate aim to decipher the paleoenvironment and post-depositional conditions of these shales and their associated features such as prominent intra-formational carbonate deposits. Sediments of the main Karoo Basin were deposited from ~350 Ma to ~182 Ma, the end of sedimentation being marked by eruption of basaltic lava. This period, which began with the Dwyka continental glaciation, included tectonism of the Cape Fold Belt, the end-Permian mass extinction at ~250 Ma, and major intrusion of dolerite associated with the lavas of the Karoo Large Igneous Province. Subsequent to this, the basin experienced faulting associated with Gondwana breakup, uplift and intrusion of small volume kimberlite and melilite magmas, and erosion resulting in formation of a major escarpment. Each episode was imprinted upon the Karoo rocks and to a greater or lesser extent erases the signature of older episodes. To decipher the depositional paleoenvironment and post-depositional conditions of the black shales and the dolomite concretions posed a challenge due to deformation, orogeny, metamorphism, and weathering and erosion. Therefore, deep borehole core-logging and sampling was generally preferred over surface fieldwork, and trace elements backed up by scanning electron microscopy-based petrography was the method most relied upon to decipher the redox conditions of the black shales and the intra-formational carbonates. Relevant sections from three SOEKOR boreholes SP1/69, AB1/65 and QU1/65 were logged and carbonate concretions localities studied in four field locations. Samples collected from the core and field localities were prepared for thin section optical, SEM petrographical analysis, mineral identification, modal estimation by XRD, major, and trace element analysis by XRF and Laser Ablation-ICPMS, and acid leaching of a sample subset to determine the degree of pyritization (DOP). Logging of the SOEKOR boreholes indicates that in the western part of the basin all three lower Ecca formations, namely the Prince Albert, Whitehill and Collingham, overlie the tillites of the Dwyka Group, whereas near East London only the Whitehill Formation is present. Dwyka diamictites occur in all the studied boreholes overlying the crystalline basement in AB 1/65 and QU 1/65 boreholes whereas in the SP 1/69 the tillites rest above the quartzite of Witteberg Group of the Cape Supergroup. The shale consists of discontinuous, wavy and straight parallel laminae. Parallel, discontinuous and elongate micro-lenses of very fine-grained quartz are diagnostic and suggest late-stage silicification. Thin laminae of black shale are interlaminated with grey clay. The black shales are composed of quartz and clay minerals (illite and chlorite) as the major crystalline minerals with minor quantities of sulphides and heavy minerals. Organic matter occurs as unstructured, anhedral patches of amorphous material. It contains abundant small (~10nm) and less common larger (~100 nm) pores of subsphaeroidal shape. Carbonates occur as cementation and concretions. Heavy minerals identified by SEM include detrital zircon, thorite, titanite, authigenic fluorite, galena, sphene, and sphalerite and apatite, monazite and epidote-group minerals that appear to be of later stage metamorphic origin, some a product of hydrothermal feldspar alteration. Zircon and monazite show evidence of partial corrosion and/or new overgrowth. Titanite occurs in greater abundance in the SP1/69 section than other boreholes, where it exhibits a porphyroblastic texture suggesting secondary growth. These features all suggest modification of detrital minerals by metamorphic fluids and therefore some possible modification of bulk geochemical composition. Pyrite is abundant, commonly occurring as framboidal and occasional euhedral grains. Pyrite-bearing, calcite veins are common in the Whitehill Formation. Some pyrite is metamorphosed to pyrrhotite in the shales adjacent to dolerite intrusions. The carbonate deposits in the lower Ecca occur mostly as large concretions of 0.5-2.5 m in diameter at intensely faulted areas, and as laterally continuous beds at less intensely faulted areas. They consist of dominant dolomite with calcite (differentiated by thin section staining) and minor associated quartz veins, and appear to have formed in an early diagenetic stage of the black shale. Five different dolomite-rock textures were identified indicating varying crystal growth conditions. Calcite cementation types accompany these dolomite textures. The major types include mosaic, sparry and bladed/prismatic calcite cement. Calcite occurs mainly as cement in pores and grain replacement, as well as crudely radial septerian veins. XRD indicates that the carbonate concretions are made up of more than 90% dolomite, especially within the intensely folded areas. The remaining 10% consist of post-depositional quartz veins and secondary calcite associated with the quartz veins. In one locality (VAAL) the carbonate samples are dominates by bladed/prismatic calcite. The black shales in this study have similar geochemical signature to previously analysed samples from the Karoo Basin and to black shales worldwide. The geochemical signature results from the combined input of detrital sedimentary materials as well as enrichment or depletions acquired from pore water, biological activity and during diagenesis. Positive correlation of K2O, Na2O with Al2O3 suggests control by the detrital contribution. CaO and P2O5, have a negative correlation with Al2O3 suggesting a biogenic source. Elemental ratios suggest that the sediments derive from felsic source rock, most likely Cape Supergroup and underlying crystalline basement. These shales exhibit different degrees of trace-element enrichment relative to global average shale, the approximate order being Pb> V> Zn> Cr> Cu> Co > Ni. Assessment of selected trace elements, V/(V+Ni), V/Cr, Ni/Co and EF Mn ratios describes the paleoenvironment of these sediments to have been partially oxygenated before sulphate reduction interface. The pyrite size distribution, DOP, Fe and S correlation points to an organic matter limited environment, where the main sulphur sink is pyrite rather than organic matter. The DOP and Fe/Al indicated that the sediments became anoxic at the sediment-water interface (early diagenetic stages). V/Cr assessment of the dolomite concretions suggested partially oxygenated environment corresponding to the black shale deposition. The occurrence of concretions at the base of the Whitehill Formation, which has the highest TOC content of 14% compared to other associated formations, is evidence that organic matter preservation was important to their origins. The parameters used here to assess the redox conditions of the black shales and the dolomite concretions in this region of the Karoo Basin suggest a normal marine redox environment, rather than the anoxic Black Sea-type environment. The conditions that affected the lower Ecca formations varied from semi-oxygenated to oxygen depletion environment. The oxygen depletion environment occurred during the deposition of the Whitehill Formation of which organic matter preservation was favoured..
- Full Text:
- Date Issued: 2019
- Authors: Maake, Laurentias Tebatso
- Date: 2019
- Subjects: Black shales -- South Africa -- Jansenville , Geochemistry Chemistry, Analytic Mineralogy -- Analysis
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/40643 , vital:36206
- Description: The Lower Permian Ecca Group formations of the Karoo Basin of South Africa have recently been identified as a target for shale gas exploration. These units, named the Prince Albert, Whitehill and Collingham formations, comprise organic-rich shales with occasional associated carbonate deposits, and siliciclastic facies. Mineralogical and geochemical investigations were conducted into carbonaceous shales and associated sedimentary rocks in the Jansenville area of the southern Karoo Basin with the ultimate aim to decipher the paleoenvironment and post-depositional conditions of these shales and their associated features such as prominent intra-formational carbonate deposits. Sediments of the main Karoo Basin were deposited from ~350 Ma to ~182 Ma, the end of sedimentation being marked by eruption of basaltic lava. This period, which began with the Dwyka continental glaciation, included tectonism of the Cape Fold Belt, the end-Permian mass extinction at ~250 Ma, and major intrusion of dolerite associated with the lavas of the Karoo Large Igneous Province. Subsequent to this, the basin experienced faulting associated with Gondwana breakup, uplift and intrusion of small volume kimberlite and melilite magmas, and erosion resulting in formation of a major escarpment. Each episode was imprinted upon the Karoo rocks and to a greater or lesser extent erases the signature of older episodes. To decipher the depositional paleoenvironment and post-depositional conditions of the black shales and the dolomite concretions posed a challenge due to deformation, orogeny, metamorphism, and weathering and erosion. Therefore, deep borehole core-logging and sampling was generally preferred over surface fieldwork, and trace elements backed up by scanning electron microscopy-based petrography was the method most relied upon to decipher the redox conditions of the black shales and the intra-formational carbonates. Relevant sections from three SOEKOR boreholes SP1/69, AB1/65 and QU1/65 were logged and carbonate concretions localities studied in four field locations. Samples collected from the core and field localities were prepared for thin section optical, SEM petrographical analysis, mineral identification, modal estimation by XRD, major, and trace element analysis by XRF and Laser Ablation-ICPMS, and acid leaching of a sample subset to determine the degree of pyritization (DOP). Logging of the SOEKOR boreholes indicates that in the western part of the basin all three lower Ecca formations, namely the Prince Albert, Whitehill and Collingham, overlie the tillites of the Dwyka Group, whereas near East London only the Whitehill Formation is present. Dwyka diamictites occur in all the studied boreholes overlying the crystalline basement in AB 1/65 and QU 1/65 boreholes whereas in the SP 1/69 the tillites rest above the quartzite of Witteberg Group of the Cape Supergroup. The shale consists of discontinuous, wavy and straight parallel laminae. Parallel, discontinuous and elongate micro-lenses of very fine-grained quartz are diagnostic and suggest late-stage silicification. Thin laminae of black shale are interlaminated with grey clay. The black shales are composed of quartz and clay minerals (illite and chlorite) as the major crystalline minerals with minor quantities of sulphides and heavy minerals. Organic matter occurs as unstructured, anhedral patches of amorphous material. It contains abundant small (~10nm) and less common larger (~100 nm) pores of subsphaeroidal shape. Carbonates occur as cementation and concretions. Heavy minerals identified by SEM include detrital zircon, thorite, titanite, authigenic fluorite, galena, sphene, and sphalerite and apatite, monazite and epidote-group minerals that appear to be of later stage metamorphic origin, some a product of hydrothermal feldspar alteration. Zircon and monazite show evidence of partial corrosion and/or new overgrowth. Titanite occurs in greater abundance in the SP1/69 section than other boreholes, where it exhibits a porphyroblastic texture suggesting secondary growth. These features all suggest modification of detrital minerals by metamorphic fluids and therefore some possible modification of bulk geochemical composition. Pyrite is abundant, commonly occurring as framboidal and occasional euhedral grains. Pyrite-bearing, calcite veins are common in the Whitehill Formation. Some pyrite is metamorphosed to pyrrhotite in the shales adjacent to dolerite intrusions. The carbonate deposits in the lower Ecca occur mostly as large concretions of 0.5-2.5 m in diameter at intensely faulted areas, and as laterally continuous beds at less intensely faulted areas. They consist of dominant dolomite with calcite (differentiated by thin section staining) and minor associated quartz veins, and appear to have formed in an early diagenetic stage of the black shale. Five different dolomite-rock textures were identified indicating varying crystal growth conditions. Calcite cementation types accompany these dolomite textures. The major types include mosaic, sparry and bladed/prismatic calcite cement. Calcite occurs mainly as cement in pores and grain replacement, as well as crudely radial septerian veins. XRD indicates that the carbonate concretions are made up of more than 90% dolomite, especially within the intensely folded areas. The remaining 10% consist of post-depositional quartz veins and secondary calcite associated with the quartz veins. In one locality (VAAL) the carbonate samples are dominates by bladed/prismatic calcite. The black shales in this study have similar geochemical signature to previously analysed samples from the Karoo Basin and to black shales worldwide. The geochemical signature results from the combined input of detrital sedimentary materials as well as enrichment or depletions acquired from pore water, biological activity and during diagenesis. Positive correlation of K2O, Na2O with Al2O3 suggests control by the detrital contribution. CaO and P2O5, have a negative correlation with Al2O3 suggesting a biogenic source. Elemental ratios suggest that the sediments derive from felsic source rock, most likely Cape Supergroup and underlying crystalline basement. These shales exhibit different degrees of trace-element enrichment relative to global average shale, the approximate order being Pb> V> Zn> Cr> Cu> Co > Ni. Assessment of selected trace elements, V/(V+Ni), V/Cr, Ni/Co and EF Mn ratios describes the paleoenvironment of these sediments to have been partially oxygenated before sulphate reduction interface. The pyrite size distribution, DOP, Fe and S correlation points to an organic matter limited environment, where the main sulphur sink is pyrite rather than organic matter. The DOP and Fe/Al indicated that the sediments became anoxic at the sediment-water interface (early diagenetic stages). V/Cr assessment of the dolomite concretions suggested partially oxygenated environment corresponding to the black shale deposition. The occurrence of concretions at the base of the Whitehill Formation, which has the highest TOC content of 14% compared to other associated formations, is evidence that organic matter preservation was important to their origins. The parameters used here to assess the redox conditions of the black shales and the dolomite concretions in this region of the Karoo Basin suggest a normal marine redox environment, rather than the anoxic Black Sea-type environment. The conditions that affected the lower Ecca formations varied from semi-oxygenated to oxygen depletion environment. The oxygen depletion environment occurred during the deposition of the Whitehill Formation of which organic matter preservation was favoured..
- Full Text:
- Date Issued: 2019
Ecological assessment and biogeography of coastal vegetation and flora in southern Mozambique
- Authors: Massingue, Alice Obed
- Date: 2019
- Subjects: Coastal plants -- Mozambique , Coastal plants Marine biodiversity -- Mozambique Coastal biodiversity -- Mozambique
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10948/40988 , vital:36280
- Description: This study considered aspects of the vegetation of the coastal zone of southern Mozambique, an area with a rich biodiversity. The vegetation and flora were assessed in their current state including the associated anthropogenic pressures. The environmental conditions that determined the distribution of the vegetation were evaluated. A hierarchical classification, description and ecological interpretation of the vegetation and flora of the coastal zone in southern Mozambique are presented. Analysis was based on 242 sample quadrats that were distributed in a stratified manner throughout the study area. The vegetation could be grouped into six distinct types of vegetation: Dune Forest, Coastal Forest, Coastal Grassland, Coastal Miombo, Coastal Savanna and Coastal Woodland. Species diversity was high for the all the vegetation types, particularly in the woody elements. A total of 673 species in 410 genera was recorded. They represented 104 families with Fabaceae and Rubiaceae being the most common. Of these, 6.6% were endemic or near-endemic to the coastal zone of southern Mozambique with Coastal Forest being the habitat with the greatest endemism. All soils from different vegetation types had poor agricultural potential. Soil properties were the strongest defining environmental feature separating the vegetation types: e.g. pH was high in Dune Forest compared to the others. Results from Maxent modelling suggest that the distribution of endemic species is influenced by a combination of climatic and non-climatic variables. Soil type, temperature annual range and precipitation of the driest month were the most important predictor variables. Overlaying the potential distributions of the seven selected species indicated two areas of abundance of endemic species – these should be given attention for conservation. Endemic species are not well protected in southern Mozambique – their sampled and potential habitats are largely outside protected areas. Hence, additional reserves should be created to improve their protection. Most endemic and near-endemics species were found in the south, from Ponta de Ouro (Matutuine, south of Maputo Province) to Manhica district (north of the Maputo Province) forming part of the Maputaland Centre of Endemism. A second concentration of endemism was found in the Inhambane Province, specifically the Inhassoro and Vilanculos districts. This is proposed to be an Important Plants Area (IPA). Because most endemics and near-endemics are found in the Coastal Forest, their main threat is harvesting for charcoal production, although none of the endemic species are specifically targeted for charcoal production. In Inhambane they are also threatened by the tourism industry, agriculture and settlements. The impact of the habitat destruction on endemic species is expected to cause severe declines in the near future. The tourism industry and harvesting of trees for charcoal production and over-frequent fires are the main drivers of vegetation loss in this region. Shifting agriculture, harvesting for firewood and construction materials, cattle grazing (at a minor scale) are also impacts, but these were only observed in a small area of Maputo Province. Although the study was done in coastal zone of southern Mozambique, effective management of whole coastal zone of the country will be required to maintain a functioning and diverse ecosystem. Priorities for management are to ensure that forests are protected, in particular, Dune Forest. Actions are required to minimise degradation of coastal vegetation. Further research on Coastal Forest restoration should be planned, as field observations in this study confirm that forest in the coastal zone of southern Mozambique has resilience.
- Full Text:
- Date Issued: 2019
- Authors: Massingue, Alice Obed
- Date: 2019
- Subjects: Coastal plants -- Mozambique , Coastal plants Marine biodiversity -- Mozambique Coastal biodiversity -- Mozambique
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10948/40988 , vital:36280
- Description: This study considered aspects of the vegetation of the coastal zone of southern Mozambique, an area with a rich biodiversity. The vegetation and flora were assessed in their current state including the associated anthropogenic pressures. The environmental conditions that determined the distribution of the vegetation were evaluated. A hierarchical classification, description and ecological interpretation of the vegetation and flora of the coastal zone in southern Mozambique are presented. Analysis was based on 242 sample quadrats that were distributed in a stratified manner throughout the study area. The vegetation could be grouped into six distinct types of vegetation: Dune Forest, Coastal Forest, Coastal Grassland, Coastal Miombo, Coastal Savanna and Coastal Woodland. Species diversity was high for the all the vegetation types, particularly in the woody elements. A total of 673 species in 410 genera was recorded. They represented 104 families with Fabaceae and Rubiaceae being the most common. Of these, 6.6% were endemic or near-endemic to the coastal zone of southern Mozambique with Coastal Forest being the habitat with the greatest endemism. All soils from different vegetation types had poor agricultural potential. Soil properties were the strongest defining environmental feature separating the vegetation types: e.g. pH was high in Dune Forest compared to the others. Results from Maxent modelling suggest that the distribution of endemic species is influenced by a combination of climatic and non-climatic variables. Soil type, temperature annual range and precipitation of the driest month were the most important predictor variables. Overlaying the potential distributions of the seven selected species indicated two areas of abundance of endemic species – these should be given attention for conservation. Endemic species are not well protected in southern Mozambique – their sampled and potential habitats are largely outside protected areas. Hence, additional reserves should be created to improve their protection. Most endemic and near-endemics species were found in the south, from Ponta de Ouro (Matutuine, south of Maputo Province) to Manhica district (north of the Maputo Province) forming part of the Maputaland Centre of Endemism. A second concentration of endemism was found in the Inhambane Province, specifically the Inhassoro and Vilanculos districts. This is proposed to be an Important Plants Area (IPA). Because most endemics and near-endemics are found in the Coastal Forest, their main threat is harvesting for charcoal production, although none of the endemic species are specifically targeted for charcoal production. In Inhambane they are also threatened by the tourism industry, agriculture and settlements. The impact of the habitat destruction on endemic species is expected to cause severe declines in the near future. The tourism industry and harvesting of trees for charcoal production and over-frequent fires are the main drivers of vegetation loss in this region. Shifting agriculture, harvesting for firewood and construction materials, cattle grazing (at a minor scale) are also impacts, but these were only observed in a small area of Maputo Province. Although the study was done in coastal zone of southern Mozambique, effective management of whole coastal zone of the country will be required to maintain a functioning and diverse ecosystem. Priorities for management are to ensure that forests are protected, in particular, Dune Forest. Actions are required to minimise degradation of coastal vegetation. Further research on Coastal Forest restoration should be planned, as field observations in this study confirm that forest in the coastal zone of southern Mozambique has resilience.
- Full Text:
- Date Issued: 2019
The hypolithic invertebrate community in the eastern Karoo: the role of rock size, microclimate and recolonization
- Authors: Van der Westhuizen, Tara
- Date: 2019
- Subjects: Habitat (Ecology) -- South Africa -- Karoo , Biotic communities -- South Africa -- Karoo Invertebrates Ecosystem management -- South Africa -- Karoo Soil microbial ecology
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/44191 , vital:37128
- Description: Hypolithic habitats are important for the persistence of fauna that utilize these habitats as refuges and resource patches. Little is known, however, about the composition and structure of this community in the semi-arid Karoo. The current study therefore aims to explore the patterns and processes behind hypolithic communities, through determining the effect of rock size and baboon presence on the hypolithic community, the influence of rock size on the microclimate experienced under rocks, as well as determining the short- (over five days) and long- (over 12 months) term colonisation of the hypolithic habitat following a rock rolling disturbance, in a semi-arid Karoo environment. The hypolithic fauna encountered, and the temperature and moisture content experienced under a range of rock sizes were measured. Additionally, hypolithic fauna under rocks that were rolled to mimic rock rolling by baboons were sampled after a set period (i.e. over five days and 12 months). Large rocks were found to provide a more stable microclimate than small rocks. The probability of hypolithic fauna presence was influenced by rock size and season, and hypolithic fauna abundance (except in the dry season), richness, body size and biomass did not correlate with rock size. Additionally, the probability of detecting hypolithic fauna under intermediate sized and larger rocks was greater in the presence of baboons than in the absence of baboons, and in the presence of baboons hypolithic fauna richness increased with rock size. Furthermore, it was shown that hypolithic fauna abundance and biomass did not differ under rolled rocks over a short- (i.e. over five days) or long- (i.e. over 12 months) term period. The short-term colonisation of hypolithic habitats was not influenced by season or rock density. Lastly, most of the change in hypolithic community composition (over 12 months) occurred in the first three months and thereafter the hypolithic community composition approached pre-disturbance levels in month 12. The hypolithic habitat was shown to be influenced by a variety of conditions and processes affecting hypolithic community composition and structure. This study therefore contributes to our understanding of the hypolithic invertebrate community in the eastern Karoo, and the influence of rock size, baboon presence, microclimate and colonisation on hypolithic community composition and structure.
- Full Text:
- Date Issued: 2019
- Authors: Van der Westhuizen, Tara
- Date: 2019
- Subjects: Habitat (Ecology) -- South Africa -- Karoo , Biotic communities -- South Africa -- Karoo Invertebrates Ecosystem management -- South Africa -- Karoo Soil microbial ecology
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/44191 , vital:37128
- Description: Hypolithic habitats are important for the persistence of fauna that utilize these habitats as refuges and resource patches. Little is known, however, about the composition and structure of this community in the semi-arid Karoo. The current study therefore aims to explore the patterns and processes behind hypolithic communities, through determining the effect of rock size and baboon presence on the hypolithic community, the influence of rock size on the microclimate experienced under rocks, as well as determining the short- (over five days) and long- (over 12 months) term colonisation of the hypolithic habitat following a rock rolling disturbance, in a semi-arid Karoo environment. The hypolithic fauna encountered, and the temperature and moisture content experienced under a range of rock sizes were measured. Additionally, hypolithic fauna under rocks that were rolled to mimic rock rolling by baboons were sampled after a set period (i.e. over five days and 12 months). Large rocks were found to provide a more stable microclimate than small rocks. The probability of hypolithic fauna presence was influenced by rock size and season, and hypolithic fauna abundance (except in the dry season), richness, body size and biomass did not correlate with rock size. Additionally, the probability of detecting hypolithic fauna under intermediate sized and larger rocks was greater in the presence of baboons than in the absence of baboons, and in the presence of baboons hypolithic fauna richness increased with rock size. Furthermore, it was shown that hypolithic fauna abundance and biomass did not differ under rolled rocks over a short- (i.e. over five days) or long- (i.e. over 12 months) term period. The short-term colonisation of hypolithic habitats was not influenced by season or rock density. Lastly, most of the change in hypolithic community composition (over 12 months) occurred in the first three months and thereafter the hypolithic community composition approached pre-disturbance levels in month 12. The hypolithic habitat was shown to be influenced by a variety of conditions and processes affecting hypolithic community composition and structure. This study therefore contributes to our understanding of the hypolithic invertebrate community in the eastern Karoo, and the influence of rock size, baboon presence, microclimate and colonisation on hypolithic community composition and structure.
- Full Text:
- Date Issued: 2019
A Statistical assessment of available solar resource across multiple sites in South Africa
- Authors: Eastwood, Kirstie
- Date: 2019
- Subjects: Mathematical statistics
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/39907 , vital:35505
- Description: Around the globe, fossil fuels remain the primary source of energy at around 78% of the world’s total energy consumption. However, the associated carbon emissions, environmental impact, the depletion of fossil fuels and price and cost volatility are factors influencing the growing popularity of research into renewable energy. Solar power is acknowledged as the fastest-growing renewable energy, but the uncertainty surrounding the long-term projections of solar irradiance available for energy conversion is a hindrance when discussing the financial risk with potential investors. This study investigates the quality of freely available solar resource data in South Africa as well as proposes techniques for potential solar farm site comparisons. Tolerance intervals derived within a Bayesian framework provide information on the future available solar resource across multiple sites. These techniques capture the inherent variability in the available solar resource which equips investors with statistical methods that lead to the better understanding of the solar resource and thus aids in better decision-making.
- Full Text:
- Date Issued: 2019
- Authors: Eastwood, Kirstie
- Date: 2019
- Subjects: Mathematical statistics
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/39907 , vital:35505
- Description: Around the globe, fossil fuels remain the primary source of energy at around 78% of the world’s total energy consumption. However, the associated carbon emissions, environmental impact, the depletion of fossil fuels and price and cost volatility are factors influencing the growing popularity of research into renewable energy. Solar power is acknowledged as the fastest-growing renewable energy, but the uncertainty surrounding the long-term projections of solar irradiance available for energy conversion is a hindrance when discussing the financial risk with potential investors. This study investigates the quality of freely available solar resource data in South Africa as well as proposes techniques for potential solar farm site comparisons. Tolerance intervals derived within a Bayesian framework provide information on the future available solar resource across multiple sites. These techniques capture the inherent variability in the available solar resource which equips investors with statistical methods that lead to the better understanding of the solar resource and thus aids in better decision-making.
- Full Text:
- Date Issued: 2019
Development of polypropylene – waste tyre crumbs based tpe's with the aid of vistamaxxtm as a compatibiliser
- Authors: Masele, Siyamtanda
- Date: 2019
- Subjects: Polymers , Polymerization Crumb rubber Rubber
- Language: English
- Type: Thesis , Masters , MTech
- Identifier: http://hdl.handle.net/10948/42589 , vital:36670
- Description: Polypropylene (PP) is a semi crystalline thermoplastic polymer and one of the most commonly used polyolefins. It is well known for its poor impact resistance; hence, for industries such as the automotive and packaging, reinforced PP is widely used. In general plastic waste disposal is a global crisis raising environmental and human health concerns, with PP being the highest consumed polymer globally; hence a push in the reuse and recycling of PP. Recycled polypropylene has limited uses for industrial applications due to its highly reduced properties owing to the recycling process which inhabits cutting of chains lengths, broadened molecular weight distributions and compromised crystallinity. Several studies have investigated the use of reinforcing fillers and modifiers in order to improve properties of PP. Inorganic materials and minerals such as CaCO3, Mica, Talc and glass fibre are used as fillers to improve mechanical properties (tensile and hardness), but still lacks in improving the impact resistance. Thermoplastic elastomers (TPE) are typically used where elastomer and thermoplastics fail as individual components. This is because they have the benefit of thermoplastic properties at hypo ambient condition and elastomer properties such as good impact and elongation at sub-zero conditions. The study took a route of using PP and waste tyre crumb rubber (CR) material to prepare potentially low-cost waste based TPE’s, which would then inherit both properties of PP and the rubber component. VistamaxxTM 6202 (EPR), a commercial name for ethylene-propylene monomer (EPR), was used as a compatibiliser to improve interaction between PP and CR and to contribute towards the overall improvement of various properties such as mechanical properties. VistamaxxTM has a low glass transition temperature (Tg, = -30 ºC), which is important for low temperature applications such as cold storage; it also has a very high elongation and as a result contributed significantly to the overall properties when used in TPE blends. The study highlighted differences between two TPE compounding formulation pathways; namely master-batch (MB) and design of experiments (DoE). The MB formulations were blends that were prepared by a conventional way of compounding; where a pre-mixed CR/EPR blend, in the ratio of 80(CR):20(EPR), was used to form a master-batch. Results showed that there are some similarities between TPEs prepared in different ways, which suggests that the ultimate properties such as thermal stability are in fact more PP matrix based. Thermal analyses results revealed that when high amount of CR was added to the TPE blends, there was a substantial amount of residue mainly due to inherent carbon black. The degree of crystallinity of the blends decreased with increased amounts of CR irrespective of whether it was the MB or DoE blends. The MB TPE blends demonstrated that hardness is not linked to the amount of the MB nor the crystallinity of blends. Meanwhile, tensile elongation and tensile stress were affected by crystallinity. On the other hand, the impact strength findings showed that the amount of MB in TPE blends reached a threshold at 30%. The DoE based TPE blends demonstrated that the optimum mechanical properties are observed when components of the blends are incorporated individually during compounding. This was observed for impact strength, tensile stress as well as elongation at break. The results showed that the incorporation of EPR should be at least 20% for good impact and elongation properties; however, for tensile and hardness, the PP matrix must be high. The study also showed that, for better mechanical properties it was more suitable to use the blends formulated with DoE, because the master-batch approach limited the improving of the mechanical properties by an addition of up to 30% of both the CR and EPR. The storage modulus as well as the tan delta for both MB and DoE decreased when the elastomeric phases were added on both methods, whereas tan delta Tg values decreased as more of the elastomeric phase was added. Evidence from morphology studies showed that the majority of TPE blends suffer from inadequate distribution and adhesion between PP and elastomer; resulting in poor mechanical properties. Furthermore, a threshold of matrix invasion is observed from 30% and above of CR in the blend, where lack of in capsulated lamps of CR were observed hindering the stress induced crystallization and relaxation of the PP phase. The latter was observed irrespective of the type of blend, which strongly suggests and highlights the limits of blending PP with elastomers. Study demonstrated the ability of VistamaxxTM to be utilized as a binding material for PP and CR and displaying the challenges that might arise when used as a master-batch with crumb rubber.
- Full Text:
- Date Issued: 2019
- Authors: Masele, Siyamtanda
- Date: 2019
- Subjects: Polymers , Polymerization Crumb rubber Rubber
- Language: English
- Type: Thesis , Masters , MTech
- Identifier: http://hdl.handle.net/10948/42589 , vital:36670
- Description: Polypropylene (PP) is a semi crystalline thermoplastic polymer and one of the most commonly used polyolefins. It is well known for its poor impact resistance; hence, for industries such as the automotive and packaging, reinforced PP is widely used. In general plastic waste disposal is a global crisis raising environmental and human health concerns, with PP being the highest consumed polymer globally; hence a push in the reuse and recycling of PP. Recycled polypropylene has limited uses for industrial applications due to its highly reduced properties owing to the recycling process which inhabits cutting of chains lengths, broadened molecular weight distributions and compromised crystallinity. Several studies have investigated the use of reinforcing fillers and modifiers in order to improve properties of PP. Inorganic materials and minerals such as CaCO3, Mica, Talc and glass fibre are used as fillers to improve mechanical properties (tensile and hardness), but still lacks in improving the impact resistance. Thermoplastic elastomers (TPE) are typically used where elastomer and thermoplastics fail as individual components. This is because they have the benefit of thermoplastic properties at hypo ambient condition and elastomer properties such as good impact and elongation at sub-zero conditions. The study took a route of using PP and waste tyre crumb rubber (CR) material to prepare potentially low-cost waste based TPE’s, which would then inherit both properties of PP and the rubber component. VistamaxxTM 6202 (EPR), a commercial name for ethylene-propylene monomer (EPR), was used as a compatibiliser to improve interaction between PP and CR and to contribute towards the overall improvement of various properties such as mechanical properties. VistamaxxTM has a low glass transition temperature (Tg, = -30 ºC), which is important for low temperature applications such as cold storage; it also has a very high elongation and as a result contributed significantly to the overall properties when used in TPE blends. The study highlighted differences between two TPE compounding formulation pathways; namely master-batch (MB) and design of experiments (DoE). The MB formulations were blends that were prepared by a conventional way of compounding; where a pre-mixed CR/EPR blend, in the ratio of 80(CR):20(EPR), was used to form a master-batch. Results showed that there are some similarities between TPEs prepared in different ways, which suggests that the ultimate properties such as thermal stability are in fact more PP matrix based. Thermal analyses results revealed that when high amount of CR was added to the TPE blends, there was a substantial amount of residue mainly due to inherent carbon black. The degree of crystallinity of the blends decreased with increased amounts of CR irrespective of whether it was the MB or DoE blends. The MB TPE blends demonstrated that hardness is not linked to the amount of the MB nor the crystallinity of blends. Meanwhile, tensile elongation and tensile stress were affected by crystallinity. On the other hand, the impact strength findings showed that the amount of MB in TPE blends reached a threshold at 30%. The DoE based TPE blends demonstrated that the optimum mechanical properties are observed when components of the blends are incorporated individually during compounding. This was observed for impact strength, tensile stress as well as elongation at break. The results showed that the incorporation of EPR should be at least 20% for good impact and elongation properties; however, for tensile and hardness, the PP matrix must be high. The study also showed that, for better mechanical properties it was more suitable to use the blends formulated with DoE, because the master-batch approach limited the improving of the mechanical properties by an addition of up to 30% of both the CR and EPR. The storage modulus as well as the tan delta for both MB and DoE decreased when the elastomeric phases were added on both methods, whereas tan delta Tg values decreased as more of the elastomeric phase was added. Evidence from morphology studies showed that the majority of TPE blends suffer from inadequate distribution and adhesion between PP and elastomer; resulting in poor mechanical properties. Furthermore, a threshold of matrix invasion is observed from 30% and above of CR in the blend, where lack of in capsulated lamps of CR were observed hindering the stress induced crystallization and relaxation of the PP phase. The latter was observed irrespective of the type of blend, which strongly suggests and highlights the limits of blending PP with elastomers. Study demonstrated the ability of VistamaxxTM to be utilized as a binding material for PP and CR and displaying the challenges that might arise when used as a master-batch with crumb rubber.
- Full Text:
- Date Issued: 2019
Design of metal ion-selective reagents for recovery of precious metals
- Authors: Moleko-Boyce, Pulleng
- Date: 2019
- Subjects: Bioinorganic chemistry , Metal complexes Speciation (Chemistry)
- Language: English
- Type: Thesis , Doctoral , DPhil
- Identifier: http://hdl.handle.net/10948/42510 , vital:36664
- Description: The study is divided into two sections; namely, (1) the design of rhodium(III) specific chelating ligands (tridentate bis-benzimidazole derivatives), and (2) the development of iridium(IV)-specific quaternary diammonium cations with electron donating and electron withdrawing groups. Bis-benzimidazole chelating ligands used were bis((1H-benzimidazol-2-yl)methyl)amine (NNN1), bis((1H-benzimidazol-2-yl)ethyl)amine (NNN2), bis((1H-benzimidazol-2-yl)methyl)sulfide (NSN1) and bis((1H-benzimidazol-2-yl)ethyl)sulfide (NSN2). Quaternary diammonium cations used were tetramethylbenzyl-1,10-diammonium chloride (QuatDMDAMeBnz), tetrabenzyl-1,10-diammonium chloride (QuatDMDABnz), tetratrifluoromethylbenzyl-1,10-diammonium chloride (QuatDMDACF3Bnz) and tetranitrobenzyl-1,10-diammonium chloride (QuatDMDANO2Bnz). For both studies, polyvinylbenzylchloride (PVBC) nanofibers were used as support material. The PVBC nanofibers which were functionalised with bis-benzimidazole derivatives and quaternary diammonium cations, respectively, were investigated for the selectivity for Rh(III) over Ir(III), Pt(II), Pd(II) and Ni(II), and for separation of Ir(IV) from Rh(III), respectively. The sorbent materials were characterised by FTIR, SEM, BET surface area, TGA, EDS and elemental analysis, and the results showed that the functionalization of the sorbent materials was successful.The efficiency of bis-benzimidazole derivatives and quaternary diammonium cations, respectively, were investigated in a column study under dynamic flow adsorption conditions. The adsorption kinetics and isotherms were investigated under batch conditions and fitted on pseudo-first-order and pseudo-second-order model, and Freundlich and Langmuir isotherm, respectively. It was observed that the bis-benzimidazole derivatives showed uptake of [RhCl3(H2O)3], and the loading capacities were observed in the following order; NSN1 (181.06 mg/g) > NSN2 (148.55 mg/g) > NNN1 (131.88 mg/g) > NNN2 (75.87 mg/g). The bis-benzimidazole derivatives preference for metal ions was further investigated with a multi-element solution containing Rh(III), Ir(III), Pt(II), Pd(II) and Ni(II). The bis-benzimidazole derivatives showed the following order of loading capacity: NSN1 (47.28 mg/g) > NSN2 (23.89 mg/g) > NNN1 (17.47 mg/g) > NNN2 (14.91 mg/g) for Rh(III); NSN2 (10.64 mg/g) > NNN2 (6.84 mg/g) > NSN1 (5.74 mg/g) > NNN1 (5.02 mg/g) for Ir(III); NNN2 (33.96 mg/g) > NSN1 (30.95 mg/g) > NSN2 (19.95 mg/g) > NNN1 (14.92 mg/g) for Pt(II); NNN1 (47.94 mg/g) > NNN2 (28.90 mg/g) > NSN1 (16.22 mg/g) > NSN2 (15.83 mg/g) for Pd(II). Bis-benzimidazole derivatives showed no uptake of nickel(II) under these conditions. It was observed the ligand-selectivity order for Rh(III) was similar in both single-element and multi-element studies. This order showed that the bis-benzimidazoles containing a sulfur atom showed a high preference for rhodium(III) compared to Pt(II) which had a high preference for NNN2 as well as Pd(II) which had a high preference for NNN1. Ir(III) generally had a lower preference for the ligands presumably due to its higher kinetic inertness compared with Rh(III). Column sorption of [IrCl6]2- and [RhCl5(H2O)]2- on nanofibers functionalized with diammonium cations was carried out and the loading capacities of [IrCl6]2- were obtained. [RhCl5(H2O)]2- was not adsorbed by the sorbent materials while [IrCl6]2- was loaded onto the column. The loading capacities of [IrCl6]2- with the quaternary diammonium sorbent materials increased in the order of F-QuatDMDAMeBnz (60.29 mg/g) < F-QuatDMDABnz (67.61 mg/g) < F-QuatDMDACF3Bnz (107.59 mg/g) < F-QuatDMDANO2Bnz (140.47 mg/g). The loading capacity for Ir(IV) with quaternary diammonium cationic nanofibers increased with an increase in the electron-withdrawing nature of the quaternizing group. The charge delocalizing ability of the nitrobenzyl group resulted in the best interaction of the diammonium cation with [IrCl6]2-. Batch equilibrium studies were carried out to assess the efficiency of bis-benzimidazole chelating derivatives as adsorbents using a multi-metal solution (Rh(III), Ir(III), Pt(II), Pd(II) and Ni(II)) in 0.5 M HCl. The efficiency of the quaternary diammonium cations was tested using a binary metal solution (Ir(IV) and Rh(III)) in 6 M HCl. The isothermal batch adsorption studies of a multi-metal solution with bis-benzimidazoles derivatives fitted the Langmuir isotherm model which confirmed monolayer adsorption onto a homogeneous surface. The Langmuir isotherm parameter (qe (mg/g)), using functionalized nanofibers, showed the order of NNN2 (128.21 mg/g) > NSN1 (99.01 mg/g) > NSN2 (91.74 mg/g) > NNN1 (84.03 mg/g) for Pt(II); NNN1 (66.23 mg/g) > NNN2 (5.89 mg/g) > NSN1 (1.40 mg/g) > NSN2 (0.59 mg/g) for Pd(II); NSN2 (10.64 mg/g) > NNN2 (6.84 mg/g) > NSN1 (5.74 mg/g) > NNN1 (5.02 mg/g) for Ir(III); NSN1 (140.85 mg/g) > NSN2 (109.89 mg/g) > NNN1 (104.17 mg/g) > NNN2 (91.74 mg/g) for Rh(III). The pseudo-first-order kinetics model was found to be the best fit to describe the adsorption kinetics of all metal ions onto all the sorbent materials. K1 (min-1) value in pseudo-first-order kinetics showed the same order of adsorption as observed in the Langmuir isotherms. The isothermal batch adsorption studies of [IrCl6]2- and [RhCl5(H2O)]2- with quaternary diammonium cations fitted the Freundlich isotherm model and confirmed to be effective for multiple-layered adsorption onto a heterogeneous surface. The Freundlich isotherm parameter (kf (mg/g)) using functionalized quaternary diammonium cationic nanofibers increased in the order of F-QuatDMDANO2Bnz (794.33 mg/g) > F-QuatDMDACF3Bnz (185.35 mg/g) > F-QuatDMDABnz (156.32 mg/g) > F-QuatDMDAMeBnz (112.46 mg/g) for Ir(IV) uptake. F-QuatDMDANO2Bnz resin showed the highest adsorption than that of F-QuatDMDAMeBnz, F-QuatDMDABnz and F-QuatDMDACF3Bnz and this order is similar to what was observed in column studies. The quaternary diammonium cations were shown to have the highest adsorption capacity for Ir(IV) compared with Rh(III). The adsorption of Rh(III) was also observed to increase in the order of F-QuatDMDANO2Bnz (177.83 mg/g) > F-QuatDMDACF3Bnz (40.37 mg/g) > F-QuatDMDABnz (36.98 mg/g) > F-QuatDMDAMeBnz (12.71 mg/g). The pseudo-second-order kinetic model was found to be the best fit to describe the adsorption kinetics of both metal ions onto all the sorbent materials. K2 (g.mg-1min-1) value in pseudo-second-order kinetics showed the same order of adsorption as observed in the Freundlich isotherms. The adsorption studies showed adsorption takes place via chemisorption process. This thesis presents PGMs and iridium-specific materials that could be applied in solutions of secondary PGMs sources containing rhodium, platinum and palladium with bis-benzimidazoles as well as in feed solutions from ore processing with diammonium cations for iridium recovery.
- Full Text:
- Date Issued: 2019
- Authors: Moleko-Boyce, Pulleng
- Date: 2019
- Subjects: Bioinorganic chemistry , Metal complexes Speciation (Chemistry)
- Language: English
- Type: Thesis , Doctoral , DPhil
- Identifier: http://hdl.handle.net/10948/42510 , vital:36664
- Description: The study is divided into two sections; namely, (1) the design of rhodium(III) specific chelating ligands (tridentate bis-benzimidazole derivatives), and (2) the development of iridium(IV)-specific quaternary diammonium cations with electron donating and electron withdrawing groups. Bis-benzimidazole chelating ligands used were bis((1H-benzimidazol-2-yl)methyl)amine (NNN1), bis((1H-benzimidazol-2-yl)ethyl)amine (NNN2), bis((1H-benzimidazol-2-yl)methyl)sulfide (NSN1) and bis((1H-benzimidazol-2-yl)ethyl)sulfide (NSN2). Quaternary diammonium cations used were tetramethylbenzyl-1,10-diammonium chloride (QuatDMDAMeBnz), tetrabenzyl-1,10-diammonium chloride (QuatDMDABnz), tetratrifluoromethylbenzyl-1,10-diammonium chloride (QuatDMDACF3Bnz) and tetranitrobenzyl-1,10-diammonium chloride (QuatDMDANO2Bnz). For both studies, polyvinylbenzylchloride (PVBC) nanofibers were used as support material. The PVBC nanofibers which were functionalised with bis-benzimidazole derivatives and quaternary diammonium cations, respectively, were investigated for the selectivity for Rh(III) over Ir(III), Pt(II), Pd(II) and Ni(II), and for separation of Ir(IV) from Rh(III), respectively. The sorbent materials were characterised by FTIR, SEM, BET surface area, TGA, EDS and elemental analysis, and the results showed that the functionalization of the sorbent materials was successful.The efficiency of bis-benzimidazole derivatives and quaternary diammonium cations, respectively, were investigated in a column study under dynamic flow adsorption conditions. The adsorption kinetics and isotherms were investigated under batch conditions and fitted on pseudo-first-order and pseudo-second-order model, and Freundlich and Langmuir isotherm, respectively. It was observed that the bis-benzimidazole derivatives showed uptake of [RhCl3(H2O)3], and the loading capacities were observed in the following order; NSN1 (181.06 mg/g) > NSN2 (148.55 mg/g) > NNN1 (131.88 mg/g) > NNN2 (75.87 mg/g). The bis-benzimidazole derivatives preference for metal ions was further investigated with a multi-element solution containing Rh(III), Ir(III), Pt(II), Pd(II) and Ni(II). The bis-benzimidazole derivatives showed the following order of loading capacity: NSN1 (47.28 mg/g) > NSN2 (23.89 mg/g) > NNN1 (17.47 mg/g) > NNN2 (14.91 mg/g) for Rh(III); NSN2 (10.64 mg/g) > NNN2 (6.84 mg/g) > NSN1 (5.74 mg/g) > NNN1 (5.02 mg/g) for Ir(III); NNN2 (33.96 mg/g) > NSN1 (30.95 mg/g) > NSN2 (19.95 mg/g) > NNN1 (14.92 mg/g) for Pt(II); NNN1 (47.94 mg/g) > NNN2 (28.90 mg/g) > NSN1 (16.22 mg/g) > NSN2 (15.83 mg/g) for Pd(II). Bis-benzimidazole derivatives showed no uptake of nickel(II) under these conditions. It was observed the ligand-selectivity order for Rh(III) was similar in both single-element and multi-element studies. This order showed that the bis-benzimidazoles containing a sulfur atom showed a high preference for rhodium(III) compared to Pt(II) which had a high preference for NNN2 as well as Pd(II) which had a high preference for NNN1. Ir(III) generally had a lower preference for the ligands presumably due to its higher kinetic inertness compared with Rh(III). Column sorption of [IrCl6]2- and [RhCl5(H2O)]2- on nanofibers functionalized with diammonium cations was carried out and the loading capacities of [IrCl6]2- were obtained. [RhCl5(H2O)]2- was not adsorbed by the sorbent materials while [IrCl6]2- was loaded onto the column. The loading capacities of [IrCl6]2- with the quaternary diammonium sorbent materials increased in the order of F-QuatDMDAMeBnz (60.29 mg/g) < F-QuatDMDABnz (67.61 mg/g) < F-QuatDMDACF3Bnz (107.59 mg/g) < F-QuatDMDANO2Bnz (140.47 mg/g). The loading capacity for Ir(IV) with quaternary diammonium cationic nanofibers increased with an increase in the electron-withdrawing nature of the quaternizing group. The charge delocalizing ability of the nitrobenzyl group resulted in the best interaction of the diammonium cation with [IrCl6]2-. Batch equilibrium studies were carried out to assess the efficiency of bis-benzimidazole chelating derivatives as adsorbents using a multi-metal solution (Rh(III), Ir(III), Pt(II), Pd(II) and Ni(II)) in 0.5 M HCl. The efficiency of the quaternary diammonium cations was tested using a binary metal solution (Ir(IV) and Rh(III)) in 6 M HCl. The isothermal batch adsorption studies of a multi-metal solution with bis-benzimidazoles derivatives fitted the Langmuir isotherm model which confirmed monolayer adsorption onto a homogeneous surface. The Langmuir isotherm parameter (qe (mg/g)), using functionalized nanofibers, showed the order of NNN2 (128.21 mg/g) > NSN1 (99.01 mg/g) > NSN2 (91.74 mg/g) > NNN1 (84.03 mg/g) for Pt(II); NNN1 (66.23 mg/g) > NNN2 (5.89 mg/g) > NSN1 (1.40 mg/g) > NSN2 (0.59 mg/g) for Pd(II); NSN2 (10.64 mg/g) > NNN2 (6.84 mg/g) > NSN1 (5.74 mg/g) > NNN1 (5.02 mg/g) for Ir(III); NSN1 (140.85 mg/g) > NSN2 (109.89 mg/g) > NNN1 (104.17 mg/g) > NNN2 (91.74 mg/g) for Rh(III). The pseudo-first-order kinetics model was found to be the best fit to describe the adsorption kinetics of all metal ions onto all the sorbent materials. K1 (min-1) value in pseudo-first-order kinetics showed the same order of adsorption as observed in the Langmuir isotherms. The isothermal batch adsorption studies of [IrCl6]2- and [RhCl5(H2O)]2- with quaternary diammonium cations fitted the Freundlich isotherm model and confirmed to be effective for multiple-layered adsorption onto a heterogeneous surface. The Freundlich isotherm parameter (kf (mg/g)) using functionalized quaternary diammonium cationic nanofibers increased in the order of F-QuatDMDANO2Bnz (794.33 mg/g) > F-QuatDMDACF3Bnz (185.35 mg/g) > F-QuatDMDABnz (156.32 mg/g) > F-QuatDMDAMeBnz (112.46 mg/g) for Ir(IV) uptake. F-QuatDMDANO2Bnz resin showed the highest adsorption than that of F-QuatDMDAMeBnz, F-QuatDMDABnz and F-QuatDMDACF3Bnz and this order is similar to what was observed in column studies. The quaternary diammonium cations were shown to have the highest adsorption capacity for Ir(IV) compared with Rh(III). The adsorption of Rh(III) was also observed to increase in the order of F-QuatDMDANO2Bnz (177.83 mg/g) > F-QuatDMDACF3Bnz (40.37 mg/g) > F-QuatDMDABnz (36.98 mg/g) > F-QuatDMDAMeBnz (12.71 mg/g). The pseudo-second-order kinetic model was found to be the best fit to describe the adsorption kinetics of both metal ions onto all the sorbent materials. K2 (g.mg-1min-1) value in pseudo-second-order kinetics showed the same order of adsorption as observed in the Freundlich isotherms. The adsorption studies showed adsorption takes place via chemisorption process. This thesis presents PGMs and iridium-specific materials that could be applied in solutions of secondary PGMs sources containing rhodium, platinum and palladium with bis-benzimidazoles as well as in feed solutions from ore processing with diammonium cations for iridium recovery.
- Full Text:
- Date Issued: 2019
Comparison of mesozooplankton communities at three shallow seamounts in the South West Indian Ocean using size spectrum analysis
- Rasoloarijao, Zo, Huggett, Jenny
- Authors: Rasoloarijao, Zo , Huggett, Jenny
- Date: 2019
- Subjects: Seamounts
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/43012 , vital:36731
- Description: Seamounts influence ocean dynamics and consequently the surrounding ecosystem. Zooplankton communities associated with seamounts may be influenced by various mechanisms related to increased retention,such as Taylor columns and/or enhanced local productivity, leading to increased predation pressure. Through this study we investigated mesozooplankton distribution and community structure in the vicinity of three shallow seamounts in the South West Indian Ocean (SWIO) during September 2016, December 2016 and April/May 2017 at La Pérouse, MadRidge and Walters Shoal respectively. The water-column was profiled at 42 stations using a CTD-F equipped with a L-ADCP and mesozooplankton was sampled with a Bongo net or a Hydrobios Midi MultiNet, both fitted with 200 µm mesh. Walters Shoal had significantly lower mesozooplankton total abundance and biovolume compared to La Perouse and MadRidge. La Perouse and MadRidge showed similar mesozooplankton community structures with steep Normalised Biovolume Size Spectrum (NBSS) slopes, indicating higher productivity and dominance of small organisms, compared to Walters Shoal where the slopes were flatter. Total and per taxon abundances and biovolumes at locations “On” and “Off” the seamount were similar, as was the size diversity for MadRidge and Walter Shoal. None of the environmental parameters tested had a significant effect on variability of the mesozooplankton community structure at the stations overall.
- Full Text:
- Date Issued: 2019
- Authors: Rasoloarijao, Zo , Huggett, Jenny
- Date: 2019
- Subjects: Seamounts
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/43012 , vital:36731
- Description: Seamounts influence ocean dynamics and consequently the surrounding ecosystem. Zooplankton communities associated with seamounts may be influenced by various mechanisms related to increased retention,such as Taylor columns and/or enhanced local productivity, leading to increased predation pressure. Through this study we investigated mesozooplankton distribution and community structure in the vicinity of three shallow seamounts in the South West Indian Ocean (SWIO) during September 2016, December 2016 and April/May 2017 at La Pérouse, MadRidge and Walters Shoal respectively. The water-column was profiled at 42 stations using a CTD-F equipped with a L-ADCP and mesozooplankton was sampled with a Bongo net or a Hydrobios Midi MultiNet, both fitted with 200 µm mesh. Walters Shoal had significantly lower mesozooplankton total abundance and biovolume compared to La Perouse and MadRidge. La Perouse and MadRidge showed similar mesozooplankton community structures with steep Normalised Biovolume Size Spectrum (NBSS) slopes, indicating higher productivity and dominance of small organisms, compared to Walters Shoal where the slopes were flatter. Total and per taxon abundances and biovolumes at locations “On” and “Off” the seamount were similar, as was the size diversity for MadRidge and Walter Shoal. None of the environmental parameters tested had a significant effect on variability of the mesozooplankton community structure at the stations overall.
- Full Text:
- Date Issued: 2019
Applications of complex functions on problems in Banach algebras
- Authors: Snyman, Jandré Dillon
- Date: 2019
- Subjects: Banach algebras , Functions of several complex variables
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/48643 , vital:41055
- Description: In this dissertation, we provide applications of complex function theory to problems in Banach algebras. We discuss the structure of analytic functions f : D → A, where D is a domain of C and A is a Banach algebra as given by Aupetit in [3]: either the set {λ ∈ D : Sp(f(λ)) is finite} is of capacity zero, or there exists an integer n such that Sp(f(λ)) has exactly n elements, for every λ, except on a closed, discrete set of capacity zero, where the spectrum has at most n−1 elements. This deep result, which describes the structure of Sp(f(λ)) for all λ ∈ D, relies heavily on subharmonic techniques, which are also included in the dissertation. Let A and B be Banach algebras. A linear mapping φ : A → B is called a Jordan homomorphism if and only if φ(xy + yx) = φ(x)φ(y) + φ(y)φ(x) for every x, y ∈ A. This is equivalent to saying that φ(x 2 ) = φ(x) 2 for every x ∈ A. The following problem, due to I. Kaplansky, is still unsolved for the general Banach algebra case: Let A and B be unital Banach algebras and φ : A → B a unital, invertibility preserving linear mapping. Under what conditions of A and B is φ a Jordan homomorphism? The author’s honours project [24] served as an exposition of the GleasonKahane-Żelazko Theorem [7, Theorem 4], which provides an answer to Kaplansky’s problem in the case where B = C. In this dissertation we look at other special cases of Kaplansky’s problem, such as the case where A and B are von Neumann algberas, as solved by Aupetit [4, Theorem 1.3] and remark that his result holds for the more general case where A is any C ∗ -algebra that has the property that every self-adjoint element is the limit of a sequence of linear combinations of orthogonal idempotents in A, and B is a semi-simple Banach algebra. This result relies heavily on complex function theory, spectral theory and holomorphic functional calculus. We also provide detailed expositions of the work of Taylor [27] in which an operator calculus on undounded, closed linear operators is developed, and the work of Allan [1] in which a holomorphic functional calculus is defined for locally convex algebras.
- Full Text:
- Date Issued: 2019
- Authors: Snyman, Jandré Dillon
- Date: 2019
- Subjects: Banach algebras , Functions of several complex variables
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/48643 , vital:41055
- Description: In this dissertation, we provide applications of complex function theory to problems in Banach algebras. We discuss the structure of analytic functions f : D → A, where D is a domain of C and A is a Banach algebra as given by Aupetit in [3]: either the set {λ ∈ D : Sp(f(λ)) is finite} is of capacity zero, or there exists an integer n such that Sp(f(λ)) has exactly n elements, for every λ, except on a closed, discrete set of capacity zero, where the spectrum has at most n−1 elements. This deep result, which describes the structure of Sp(f(λ)) for all λ ∈ D, relies heavily on subharmonic techniques, which are also included in the dissertation. Let A and B be Banach algebras. A linear mapping φ : A → B is called a Jordan homomorphism if and only if φ(xy + yx) = φ(x)φ(y) + φ(y)φ(x) for every x, y ∈ A. This is equivalent to saying that φ(x 2 ) = φ(x) 2 for every x ∈ A. The following problem, due to I. Kaplansky, is still unsolved for the general Banach algebra case: Let A and B be unital Banach algebras and φ : A → B a unital, invertibility preserving linear mapping. Under what conditions of A and B is φ a Jordan homomorphism? The author’s honours project [24] served as an exposition of the GleasonKahane-Żelazko Theorem [7, Theorem 4], which provides an answer to Kaplansky’s problem in the case where B = C. In this dissertation we look at other special cases of Kaplansky’s problem, such as the case where A and B are von Neumann algberas, as solved by Aupetit [4, Theorem 1.3] and remark that his result holds for the more general case where A is any C ∗ -algebra that has the property that every self-adjoint element is the limit of a sequence of linear combinations of orthogonal idempotents in A, and B is a semi-simple Banach algebra. This result relies heavily on complex function theory, spectral theory and holomorphic functional calculus. We also provide detailed expositions of the work of Taylor [27] in which an operator calculus on undounded, closed linear operators is developed, and the work of Allan [1] in which a holomorphic functional calculus is defined for locally convex algebras.
- Full Text:
- Date Issued: 2019
Determination of social, environmental and economic benefits for community participation in forestry in Mpumalanga, South Africa
- Long, Leo Searle, Chirwa, Paxie
- Authors: Long, Leo Searle , Chirwa, Paxie
- Date: 2019
- Subjects: Forests and forestry -- South Africa -- Mpumalanga
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/34339 , vital:33307
- Description: Rural communities living adjacent to commercial forestry operations are often affected by numerous negative social issues such as poverty, unemployment, poor healthcare, and limited infrastructure, amongst others. In excess of 61% of forestry land managed by the state owned SAFCOL SOC Ltd is under land claim, as part of the Restitution of Land Rights Act (Act 22 of 1994). It is therefore necessary for forest companies to seek active means of engaging and partnering with these communities through a participatory forest management (PFM) approach. This study explored the sustainable (social, environmental and economic), benefits of such an approach as perceived (experienced) by these local rural communities, and specifically land claimants. The study was conducted in communities adjacent to SAFCOL plantations in the Mpumalanga Province of South Africa. Data were collected between May and June 2017 by means of a structured questionnaire. Surveys were conducted on 46 households within the identified communities so as to verify and evaluate perceived benefits in terms of forest products, ecosystem services and amenities/services/infrastructure provided by SAFCOL and the broader forest industry. The results indicated that these communities recognize and obtain numerous social, environmental and economic benefits from the forest including Non-Timber Forest Products (NTFPs) such as firewood; forest provisioning ecosystem services (FPESs) such as improved water quality; and more metaphysical benefits such as access to gravesites and the protection of traditions and customs. These benefits have the ability to improve the social well-being, economic independence, and the quality of environmental services obtained by the associated communities. It was however found that the utilization of these benefits was widely differentiated according to gender and land claimant status. Whilst males and females largely benefitted equally, there was a distinct benefit preference between genders for different NTFPs. For example males showed preference for the collection of building material, bush meat and for livestock husbandry, whilst females showed preference for the collection of firewood, medicinal plants and fruit, amongst others. Similarly, it was found that overall, non-land claimants benefited more than land claimants. Reasons for this are primarily due to the increased distance with which the land claimants live from the forest resource when compared to non-land claimants. The empirical value of the data produced through this study will be invaluable in negotiations with the land claimant communities on land settlement agreements, joint venture proposals, including Participatory Forest Management, and future land tenure. Through such inclusivity and vested interest in the sustainable management of the forests, corporate risk is reduced and community/land claimant relationships are reinforced. Such Participatory Forest Management arrangements are key to ensuring the longevity and resilience to the forest sector post-transfer of claimed land.
- Full Text:
- Date Issued: 2019
- Authors: Long, Leo Searle , Chirwa, Paxie
- Date: 2019
- Subjects: Forests and forestry -- South Africa -- Mpumalanga
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/34339 , vital:33307
- Description: Rural communities living adjacent to commercial forestry operations are often affected by numerous negative social issues such as poverty, unemployment, poor healthcare, and limited infrastructure, amongst others. In excess of 61% of forestry land managed by the state owned SAFCOL SOC Ltd is under land claim, as part of the Restitution of Land Rights Act (Act 22 of 1994). It is therefore necessary for forest companies to seek active means of engaging and partnering with these communities through a participatory forest management (PFM) approach. This study explored the sustainable (social, environmental and economic), benefits of such an approach as perceived (experienced) by these local rural communities, and specifically land claimants. The study was conducted in communities adjacent to SAFCOL plantations in the Mpumalanga Province of South Africa. Data were collected between May and June 2017 by means of a structured questionnaire. Surveys were conducted on 46 households within the identified communities so as to verify and evaluate perceived benefits in terms of forest products, ecosystem services and amenities/services/infrastructure provided by SAFCOL and the broader forest industry. The results indicated that these communities recognize and obtain numerous social, environmental and economic benefits from the forest including Non-Timber Forest Products (NTFPs) such as firewood; forest provisioning ecosystem services (FPESs) such as improved water quality; and more metaphysical benefits such as access to gravesites and the protection of traditions and customs. These benefits have the ability to improve the social well-being, economic independence, and the quality of environmental services obtained by the associated communities. It was however found that the utilization of these benefits was widely differentiated according to gender and land claimant status. Whilst males and females largely benefitted equally, there was a distinct benefit preference between genders for different NTFPs. For example males showed preference for the collection of building material, bush meat and for livestock husbandry, whilst females showed preference for the collection of firewood, medicinal plants and fruit, amongst others. Similarly, it was found that overall, non-land claimants benefited more than land claimants. Reasons for this are primarily due to the increased distance with which the land claimants live from the forest resource when compared to non-land claimants. The empirical value of the data produced through this study will be invaluable in negotiations with the land claimant communities on land settlement agreements, joint venture proposals, including Participatory Forest Management, and future land tenure. Through such inclusivity and vested interest in the sustainable management of the forests, corporate risk is reduced and community/land claimant relationships are reinforced. Such Participatory Forest Management arrangements are key to ensuring the longevity and resilience to the forest sector post-transfer of claimed land.
- Full Text:
- Date Issued: 2019
A comparative study of artificial neural networks and physics models as simulators in evolutionary robotics
- Pretorius, Christiaan Johannes
- Authors: Pretorius, Christiaan Johannes
- Date: 2019
- Subjects: Neural networks (Computer science)
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10948/30789 , vital:31131
- Description: The Evolutionary Robotics (ER) process is a technique that applies evolutionary optimization algorithms to the task of automatically developing, or evolving, robotic control programs. These control programs, or simply controllers, are evolved in order to allow a robot to perform a required task. During the ER process, use is often made of robotic simulators to evaluate the performance of candidate controllers that are produced in the course of the controller evolution process. Such simulators accelerate and otherwise simplify the controller evolution process, as opposed to the more arduous process of evaluating controllers in the real world without use of simulation. To date, the vast majority of simulators that have been applied in ER are physics- based models which are constructed by taking into account the underlying physics governing the operation of the robotic system in question. An alternative approach to simulator implementation in ER is the usage of Artificial Neural Networks (ANNs) as simulators in the ER process. Such simulators are referred to as Simulator Neural Networks (SNNs). Previous studies have indicated that SNNs can successfully be used as an alter- native to physics-based simulators in the ER process on various robotic platforms. At the commencement of the current study it was not, however, known how this relatively new method of simulation would compare to traditional physics-based simulation approaches in ER. The study presented in this thesis thus endeavoured to quantitatively compare SNNs and physics-based models as simulators in the ER process. In order to con- duct this comparative study, both SNNs and physics simulators were constructed for the modelling of three different robotic platforms: a differentially-steered robot, a wheeled inverted pendulum robot and a hexapod robot. Each of these two types of simulation was then used in simulation-based evolution processes to evolve con- trollers for each robotic platform. During these controller evolution processes, the SNNs and physics models were compared in terms of their accuracy in making pre- dictions of robotic behaviour, their computational efficiency in arriving at these predictions, the human effort required to construct each simulator and, most im- portantly, the real-world performance of controllers evolved by making use of each simulator. The results obtained in this study illustrated experimentally that SNNs were, in the majority of cases, able to make more accurate predictions than the physics- based models and these SNNs were arguably simpler to construct than the physics simulators. Additionally, SNNs were also shown to be a computationally efficient alternative to physics-based simulators in ER and, again in the majority of cases, these SNNs were able to produce controllers which outperformed those evolved in the physics-based simulators, when these controllers were uploaded to the real-world robots. The results of this thesis thus suggest that SNNs are a viable alternative to more commonly-used physics simulators in ER and further investigation of the potential of this simulation technique appears warranted.
- Full Text:
- Date Issued: 2019
- Authors: Pretorius, Christiaan Johannes
- Date: 2019
- Subjects: Neural networks (Computer science)
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10948/30789 , vital:31131
- Description: The Evolutionary Robotics (ER) process is a technique that applies evolutionary optimization algorithms to the task of automatically developing, or evolving, robotic control programs. These control programs, or simply controllers, are evolved in order to allow a robot to perform a required task. During the ER process, use is often made of robotic simulators to evaluate the performance of candidate controllers that are produced in the course of the controller evolution process. Such simulators accelerate and otherwise simplify the controller evolution process, as opposed to the more arduous process of evaluating controllers in the real world without use of simulation. To date, the vast majority of simulators that have been applied in ER are physics- based models which are constructed by taking into account the underlying physics governing the operation of the robotic system in question. An alternative approach to simulator implementation in ER is the usage of Artificial Neural Networks (ANNs) as simulators in the ER process. Such simulators are referred to as Simulator Neural Networks (SNNs). Previous studies have indicated that SNNs can successfully be used as an alter- native to physics-based simulators in the ER process on various robotic platforms. At the commencement of the current study it was not, however, known how this relatively new method of simulation would compare to traditional physics-based simulation approaches in ER. The study presented in this thesis thus endeavoured to quantitatively compare SNNs and physics-based models as simulators in the ER process. In order to con- duct this comparative study, both SNNs and physics simulators were constructed for the modelling of three different robotic platforms: a differentially-steered robot, a wheeled inverted pendulum robot and a hexapod robot. Each of these two types of simulation was then used in simulation-based evolution processes to evolve con- trollers for each robotic platform. During these controller evolution processes, the SNNs and physics models were compared in terms of their accuracy in making pre- dictions of robotic behaviour, their computational efficiency in arriving at these predictions, the human effort required to construct each simulator and, most im- portantly, the real-world performance of controllers evolved by making use of each simulator. The results obtained in this study illustrated experimentally that SNNs were, in the majority of cases, able to make more accurate predictions than the physics- based models and these SNNs were arguably simpler to construct than the physics simulators. Additionally, SNNs were also shown to be a computationally efficient alternative to physics-based simulators in ER and, again in the majority of cases, these SNNs were able to produce controllers which outperformed those evolved in the physics-based simulators, when these controllers were uploaded to the real-world robots. The results of this thesis thus suggest that SNNs are a viable alternative to more commonly-used physics simulators in ER and further investigation of the potential of this simulation technique appears warranted.
- Full Text:
- Date Issued: 2019
A Model for Crime Management in Smart Cities
- Authors: Westraadt, Lindsay
- Date: 2019
- Subjects: Smart cities , Computer networks -- security measures
- Language: English
- Type: Thesis , Doctoral , PHD
- Identifier: http://hdl.handle.net/10948/45635 , vital:38922
- Description: The main research problem addressed in this study is that South African cities are not effectively integrating and utilising available, and rapidly emerging smart city data sources for planning and management. To this end, it was proposed that a predictive model, that assimilates data from traditionally isolated management silos, could be developed for prediction and simulation at the system-of-systems level. As proof of concept, the study focused on only one aspect of smart cities, namely crime management. Subsequently, the main objective of this study was to develop and evaluate a predictive model for crime management in smart cities that effectively integrated data from traditionally isolated management silos. The Design Science Research process was followed to develop and evaluate a prototype model. The practical contributions of this study was the development of a prototype model for integrated decision-making in smart cities, and the associated guidelines for the implementation of the developed modelling approach within the South African IDP context. Theoretically, this work contributed towards the development of a modelling paradigm for effective integrated decision-making in smart cities. This work also contributed towards developing strategic-level predictive policing tools aimed at proactively meeting community needs, and contributed to the body of knowledge regarding complex systems modelling.
- Full Text:
- Date Issued: 2019
- Authors: Westraadt, Lindsay
- Date: 2019
- Subjects: Smart cities , Computer networks -- security measures
- Language: English
- Type: Thesis , Doctoral , PHD
- Identifier: http://hdl.handle.net/10948/45635 , vital:38922
- Description: The main research problem addressed in this study is that South African cities are not effectively integrating and utilising available, and rapidly emerging smart city data sources for planning and management. To this end, it was proposed that a predictive model, that assimilates data from traditionally isolated management silos, could be developed for prediction and simulation at the system-of-systems level. As proof of concept, the study focused on only one aspect of smart cities, namely crime management. Subsequently, the main objective of this study was to develop and evaluate a predictive model for crime management in smart cities that effectively integrated data from traditionally isolated management silos. The Design Science Research process was followed to develop and evaluate a prototype model. The practical contributions of this study was the development of a prototype model for integrated decision-making in smart cities, and the associated guidelines for the implementation of the developed modelling approach within the South African IDP context. Theoretically, this work contributed towards the development of a modelling paradigm for effective integrated decision-making in smart cities. This work also contributed towards developing strategic-level predictive policing tools aimed at proactively meeting community needs, and contributed to the body of knowledge regarding complex systems modelling.
- Full Text:
- Date Issued: 2019
Sustainability reporting guidelines for higher educational institutions in South Africa
- Authors: Zietsman, Jaco
- Date: 2019
- Subjects: Education, Higher -- South Africa , Corporation reports Sustainability
- Language: English
- Type: Thesis , Masters , MCom
- Identifier: http://hdl.handle.net/10948/33384 , vital:32754
- Description: In the higher education sector, a number of Higher Education Institutions (HEIs) are playing a leading role in promoting sustainable initiatives. Managing these initiatives effectively can be a complex task and requires data and information from multiple sources. HEIs must ensure financial sustainability, social sustainability, environmental sustainability and educational sustainability. HEIs in South Africa are required to produce a sustainability report for the Department of Higher Education and Training (DHET) on an annual basis. HEIs are not required to use a specific set of guidelines to create a report that complies with the DHET reporting requirements. HEIs face a number of challenges in effectively managing and reporting on sustainability information, such as poor sharing and communication of information and combining information from different sources to form an integrated report. Well-structured guidelines that adheres to institution standards and governmental reporting requirements can effectively streamline the sustainability reporting process. This study investigates the requirements and challenges of effective sustainability reporting for HEIs in South Africa. A set of Global Reporting Initiative (GRI) G4 guidelines were reworked to support effective sustainability reporting by South African HEIs. Nelson Mandela University is one such HEI, which is affected by the challenges of managing and reporting on strategic sustainability information. Nelson Mandela University was therefore used as a case study in this research study. An in-depth study was done exploring how prominent international universities apply the GRI guidelines to contribute and generate integrated sustainability reports for their specific HEIs and general reporting needs and requirements. Additionally, an in-depth study of the German integrated reporting guidelines for HEI’s was conducted. Furthermore, a study of the South African DHET reporting requirements was conducted to explore the similarities that exists between the GRI (G4) guidelines and DHET requirements. The guidelines were evaluated by Nelson Mandela University personnel and academics. The final product consists of a set of GRI guidelines that have been adapted to satisfy both GRI and DHET requirements for integrated sustainability reporting for South African HEIs. The contributions from this study are a set of GRI G4 guidelines and examples for integrated sustainability reporting and management for HEIs in South Africa. The set of adapted GRI guidelines for HEIs in South Africa was created with the assistance of the strategic management departments at Nelson Mandela University. The GRI guidelines have been reworded to be specifically applicable to South African HEIs and contain instructions and guidelines on how to generate an integrated sustainability report for a South African HEI.
- Full Text:
- Date Issued: 2019
- Authors: Zietsman, Jaco
- Date: 2019
- Subjects: Education, Higher -- South Africa , Corporation reports Sustainability
- Language: English
- Type: Thesis , Masters , MCom
- Identifier: http://hdl.handle.net/10948/33384 , vital:32754
- Description: In the higher education sector, a number of Higher Education Institutions (HEIs) are playing a leading role in promoting sustainable initiatives. Managing these initiatives effectively can be a complex task and requires data and information from multiple sources. HEIs must ensure financial sustainability, social sustainability, environmental sustainability and educational sustainability. HEIs in South Africa are required to produce a sustainability report for the Department of Higher Education and Training (DHET) on an annual basis. HEIs are not required to use a specific set of guidelines to create a report that complies with the DHET reporting requirements. HEIs face a number of challenges in effectively managing and reporting on sustainability information, such as poor sharing and communication of information and combining information from different sources to form an integrated report. Well-structured guidelines that adheres to institution standards and governmental reporting requirements can effectively streamline the sustainability reporting process. This study investigates the requirements and challenges of effective sustainability reporting for HEIs in South Africa. A set of Global Reporting Initiative (GRI) G4 guidelines were reworked to support effective sustainability reporting by South African HEIs. Nelson Mandela University is one such HEI, which is affected by the challenges of managing and reporting on strategic sustainability information. Nelson Mandela University was therefore used as a case study in this research study. An in-depth study was done exploring how prominent international universities apply the GRI guidelines to contribute and generate integrated sustainability reports for their specific HEIs and general reporting needs and requirements. Additionally, an in-depth study of the German integrated reporting guidelines for HEI’s was conducted. Furthermore, a study of the South African DHET reporting requirements was conducted to explore the similarities that exists between the GRI (G4) guidelines and DHET requirements. The guidelines were evaluated by Nelson Mandela University personnel and academics. The final product consists of a set of GRI guidelines that have been adapted to satisfy both GRI and DHET requirements for integrated sustainability reporting for South African HEIs. The contributions from this study are a set of GRI G4 guidelines and examples for integrated sustainability reporting and management for HEIs in South Africa. The set of adapted GRI guidelines for HEIs in South Africa was created with the assistance of the strategic management departments at Nelson Mandela University. The GRI guidelines have been reworded to be specifically applicable to South African HEIs and contain instructions and guidelines on how to generate an integrated sustainability report for a South African HEI.
- Full Text:
- Date Issued: 2019
Vulnerability in surf tourism: surf break decline and its impact on Herold's Bay, South Africa
- Authors: Schröder, Klaus
- Date: 2019
- Subjects: Surfing -- South Africa , Tourism -- Environmental aspects Climatic changes -- South Africa
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/43501 , vital:36900
- Description: Surfing has increasingly become a mainstream and demographically diverse activity that holds substantial economic worth. It also holds substantial social, cultural and spiritual value for participants and related communities. It is therefore not surprising that the maintenance of surf breaks has become an important element of coastal tourism, and that tourism management has had a growing concern with anthropogenic impacts on the shoreline. In line with these developments, this study investigates the vulnerability of surf tourism given the general consensus that there has been a human-induced decline of the river-mouth surf break in Herold’s Bay. An adapted ecological services model is used, and in line with such models, the status of the three types of capital (natural (physical) capital, climatic capital, and built capital) and their effect on recreation capital (surfing’s participation, market, and non-market values) over a twenty-year period is tracked. The findings identified alterations to the river bed morphology, beach morphology, wind direction, and swell intensity and frequency as the main determinants in surf break decline. The corresponding increase in vulnerability of Herold’s Bay’s surf tourism industry is also given as having negative socio-economic impacts. This study has underlined both the potential and the imperative to conserve, utilise and develop surf breaks and the surf tourism industry within South Africa.
- Full Text:
- Date Issued: 2019
- Authors: Schröder, Klaus
- Date: 2019
- Subjects: Surfing -- South Africa , Tourism -- Environmental aspects Climatic changes -- South Africa
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/43501 , vital:36900
- Description: Surfing has increasingly become a mainstream and demographically diverse activity that holds substantial economic worth. It also holds substantial social, cultural and spiritual value for participants and related communities. It is therefore not surprising that the maintenance of surf breaks has become an important element of coastal tourism, and that tourism management has had a growing concern with anthropogenic impacts on the shoreline. In line with these developments, this study investigates the vulnerability of surf tourism given the general consensus that there has been a human-induced decline of the river-mouth surf break in Herold’s Bay. An adapted ecological services model is used, and in line with such models, the status of the three types of capital (natural (physical) capital, climatic capital, and built capital) and their effect on recreation capital (surfing’s participation, market, and non-market values) over a twenty-year period is tracked. The findings identified alterations to the river bed morphology, beach morphology, wind direction, and swell intensity and frequency as the main determinants in surf break decline. The corresponding increase in vulnerability of Herold’s Bay’s surf tourism industry is also given as having negative socio-economic impacts. This study has underlined both the potential and the imperative to conserve, utilise and develop surf breaks and the surf tourism industry within South Africa.
- Full Text:
- Date Issued: 2019
Bootstrap-based tolerance intervals for photovoltaic energy yield assessments
- Authors: Deyzel, Jani Igna
- Date: 2019
- Subjects: Bootstrap (Statistics) , Mathematical statistics Photovoltaic power systems
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/39469 , vital:35256
- Description: The assessment of the energy yield of a photovoltaic (PV) system is one of the key assessments required by investors and developers. Currently, available methods used for this assessment only provide a point estimate as the final assessment. This study proposes a statistical technique which provides an additional energy yield assessment method by using tolerance intervals. Variance component models are used to better account for the variability present in the daily and hourly energy yields of three different PV modules. A bootstrap-based technique is used to obtain 𝛽-expectation and (𝛼,𝛽) two-sided tolerance intervals. These tolerance intervals provided more information with a content and confidence level for seasonal and yearly time-periods. In addition, the comparisons of the PV modules provide valuable information to investors and developers.
- Full Text:
- Date Issued: 2019
- Authors: Deyzel, Jani Igna
- Date: 2019
- Subjects: Bootstrap (Statistics) , Mathematical statistics Photovoltaic power systems
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/39469 , vital:35256
- Description: The assessment of the energy yield of a photovoltaic (PV) system is one of the key assessments required by investors and developers. Currently, available methods used for this assessment only provide a point estimate as the final assessment. This study proposes a statistical technique which provides an additional energy yield assessment method by using tolerance intervals. Variance component models are used to better account for the variability present in the daily and hourly energy yields of three different PV modules. A bootstrap-based technique is used to obtain 𝛽-expectation and (𝛼,𝛽) two-sided tolerance intervals. These tolerance intervals provided more information with a content and confidence level for seasonal and yearly time-periods. In addition, the comparisons of the PV modules provide valuable information to investors and developers.
- Full Text:
- Date Issued: 2019
The ecology of Impala (Aepyceros melampus) in a dystrophic system: a case study from Welgevonden Game Reserve, Limpopo Province, South Africa
- Authors: Pieterse, Marilize
- Date: 2019
- Subjects: Impala -- Habitat -- South Africa -- Limpopo province , Impala -- Feeding and feeds -- South Africa -- Limpopo province Ecology -- South Africa -- Limpopo province
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/43240 , vital:36768
- Description: Impala (Aepyceros melampus) have been extensively researched and are known to flourish in Savanna ecosystems. They are a very adaptable species switching easily between grazing and browsing hence their classification as mixed feeders. However, little published research has been done on impala and their adaptability to sour nutrient-poor savannas. On Welgevonden Game Reserve (WGR), situated in the dystrophic Waterberg Mountain Range, impala have poor body condition and negative growth rates. Research shows that impala are on the threshold of being sexually dimorphic which can lead to a difference in the habitat selection and preference, diet composition and diet quality of adult male and female animals. This study served as a baseline study to understand the adaptability and ecology of impala in the Waterberg. The key research question was: How do male and female impala adapt to the area in terms of habitat selection and preference, and diet composition and quality, across the seasons of a year in the sour nutrient-poor Waterberg Mountain Range? This was the first study on impala in the area that looked at all the above-mentioned factors. A combination of observational studies, for habitat selection and preference, and faecal analysis, for diet composition and diet quality (faecal Nitrogen (Nf) and Phosphorous (Pf)), were used. It should be noted that WGR received below average rainfall and above average maximum temperatures over the past seven years. Impala on WGR are limited by the availability of suitable habitat and the quantity and quality of forage. They therefore suffer from nutrient deficiency. Spatial and ecological segregation between male and female animals occurred due to differences in sexual status and the constraints associated with this. Overall, very little variation in habitat use occurred between Wet and Dry seasons, emphasizing limited suitable impala habitat. Impala on WGR showed a distinct preference and avoidance of different habitat types. Both male and female preferred Short Grassland throughout the year. This is the smallest habitat type on the reserve and is dominated by Cynodon dactylon, which mostly occurs in the low-lying areas of the reserve. Both male and female impala avoided Hill Slope and Long Grassland throughout the year. These habitat types are characterized by steep slopes, medium to extensive rock cover, long sparse grass and dense tree cover. The Long Grassland habitat type consist mainly of old lands in different stages of regeneration dominated by dense unpalatable grasses. Both male and female impala were highly selective towards the most nutrient rich areas, which predominantly included the Short Grassland habitat type. The factors important to impala habitat selection are short to medium grass height (6-25 cm), ecotones in low lying areas between Short Grassland and woodland, proximity to water (0.96-1.5 km), moderate to no slopes, a burn interval of less than 3 years, the dominant occurrence of Cynodon dactylon, and the presence of Dichrostachys cinerea, Grewia flavescens, Dombeya rotundifolia and Indigofera melanodenia. The impala population on WGR appears to be limited by a lack of quality forage. The diet composition of impala on WGR followed a seasonal pattern, with a higher grass to browse content during the Wet seasons, and a higher browse to grass content during the Dry seasons. Furthermore, impala on WGR have a higher browse content in their diet than in other areas of South Africa. The higher content of browse in the impala’s diet on WGR is probably due to the impala optimizing their diet quality due to a lack of quality grasses, such as Cynodon dactylon, available to them on the reserve. Females consumed higher amounts of browse than males during lactation in order to optimize their diet quality. In general, impala experienced nutrient deficiencies during the Dry seasons as indicated by Nf and Pf values which were below the accepted threshold values for impala. This appears to have affected their body condition, reproductive success and survival. The below threshold values of Nf and Pf indicate that their numbers exceeded the ecological capacity of the reserve at the time of the study. This dystrophic savanna is marginal for impala. This indicates that even large reserves in the sour bushveld communities of the Waterberg Mountains are unlikely to sustain impala populations in a healthy productive state.
- Full Text:
- Date Issued: 2019
- Authors: Pieterse, Marilize
- Date: 2019
- Subjects: Impala -- Habitat -- South Africa -- Limpopo province , Impala -- Feeding and feeds -- South Africa -- Limpopo province Ecology -- South Africa -- Limpopo province
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/43240 , vital:36768
- Description: Impala (Aepyceros melampus) have been extensively researched and are known to flourish in Savanna ecosystems. They are a very adaptable species switching easily between grazing and browsing hence their classification as mixed feeders. However, little published research has been done on impala and their adaptability to sour nutrient-poor savannas. On Welgevonden Game Reserve (WGR), situated in the dystrophic Waterberg Mountain Range, impala have poor body condition and negative growth rates. Research shows that impala are on the threshold of being sexually dimorphic which can lead to a difference in the habitat selection and preference, diet composition and diet quality of adult male and female animals. This study served as a baseline study to understand the adaptability and ecology of impala in the Waterberg. The key research question was: How do male and female impala adapt to the area in terms of habitat selection and preference, and diet composition and quality, across the seasons of a year in the sour nutrient-poor Waterberg Mountain Range? This was the first study on impala in the area that looked at all the above-mentioned factors. A combination of observational studies, for habitat selection and preference, and faecal analysis, for diet composition and diet quality (faecal Nitrogen (Nf) and Phosphorous (Pf)), were used. It should be noted that WGR received below average rainfall and above average maximum temperatures over the past seven years. Impala on WGR are limited by the availability of suitable habitat and the quantity and quality of forage. They therefore suffer from nutrient deficiency. Spatial and ecological segregation between male and female animals occurred due to differences in sexual status and the constraints associated with this. Overall, very little variation in habitat use occurred between Wet and Dry seasons, emphasizing limited suitable impala habitat. Impala on WGR showed a distinct preference and avoidance of different habitat types. Both male and female preferred Short Grassland throughout the year. This is the smallest habitat type on the reserve and is dominated by Cynodon dactylon, which mostly occurs in the low-lying areas of the reserve. Both male and female impala avoided Hill Slope and Long Grassland throughout the year. These habitat types are characterized by steep slopes, medium to extensive rock cover, long sparse grass and dense tree cover. The Long Grassland habitat type consist mainly of old lands in different stages of regeneration dominated by dense unpalatable grasses. Both male and female impala were highly selective towards the most nutrient rich areas, which predominantly included the Short Grassland habitat type. The factors important to impala habitat selection are short to medium grass height (6-25 cm), ecotones in low lying areas between Short Grassland and woodland, proximity to water (0.96-1.5 km), moderate to no slopes, a burn interval of less than 3 years, the dominant occurrence of Cynodon dactylon, and the presence of Dichrostachys cinerea, Grewia flavescens, Dombeya rotundifolia and Indigofera melanodenia. The impala population on WGR appears to be limited by a lack of quality forage. The diet composition of impala on WGR followed a seasonal pattern, with a higher grass to browse content during the Wet seasons, and a higher browse to grass content during the Dry seasons. Furthermore, impala on WGR have a higher browse content in their diet than in other areas of South Africa. The higher content of browse in the impala’s diet on WGR is probably due to the impala optimizing their diet quality due to a lack of quality grasses, such as Cynodon dactylon, available to them on the reserve. Females consumed higher amounts of browse than males during lactation in order to optimize their diet quality. In general, impala experienced nutrient deficiencies during the Dry seasons as indicated by Nf and Pf values which were below the accepted threshold values for impala. This appears to have affected their body condition, reproductive success and survival. The below threshold values of Nf and Pf indicate that their numbers exceeded the ecological capacity of the reserve at the time of the study. This dystrophic savanna is marginal for impala. This indicates that even large reserves in the sour bushveld communities of the Waterberg Mountains are unlikely to sustain impala populations in a healthy productive state.
- Full Text:
- Date Issued: 2019
An investigation into bile formation of Wistar rats for excretion of injected gold nanoparticles
- Authors: Thole, Sagoleka Thabo
- Date: 2019
- Subjects: Nanoparticles , Nanomedicine Gold -- Immunology Bile acids -- Physiological effect
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/43900 , vital:37082
- Description: There is an increase in the use of nanoparticles (NPs) throughout the world. Gold nanoparticles (AuNPs) are commonly used NPs in the field of biomedicine. NPs bigger than 8 nm are excreted via the hepatobiliary system. Bile acids (BAs) are regarded as the main components of bile. If there is a decreased or increased secretion of BAs, the composition of microbiota in the gut can change. Under normal physiological condition BAs fluctuates daily without causing any harm. Nevertheless, it is the long-term changes in bile acid secretion that can affect microbiota in the gut. If there is an increased excretion of AuNPs via hepatobiliary pathway it can alter bile formation. The aim of this study was to investigate whether the hepatobiliary excretion of AuNPs will alter the bile formation two weeks after intravenous administration of 14 nm AuNPs to Wistar rats. Rat liver samples of two previous experiments were used to investigate bile formation. The rats had been injected intravenously with a single dose of citrate capped and functionalised AuNPs. These rats were killed 14 days later. Small pieces of liver were stored in RNAlater. The mRNA of different enzymes and transporters in the hepatobiliary system were quantified in these samples and compared with suitable control. As a reference the mRNA of the same enzymes and transporters were extracted and quantified in rat liver that were killed one day after injection with one of the abovementioned functionalised AuNPs. The study shows down-regulation of genes responsible for conjugation of BAs whereas the rate-limiting enzymes were not significantly changed. This was the first study to investigate the formation of bile in relation to the use of AuNPs. The effect and consequences of AuNPs on the hepatobiliary system need further investigation.
- Full Text:
- Date Issued: 2019
- Authors: Thole, Sagoleka Thabo
- Date: 2019
- Subjects: Nanoparticles , Nanomedicine Gold -- Immunology Bile acids -- Physiological effect
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/43900 , vital:37082
- Description: There is an increase in the use of nanoparticles (NPs) throughout the world. Gold nanoparticles (AuNPs) are commonly used NPs in the field of biomedicine. NPs bigger than 8 nm are excreted via the hepatobiliary system. Bile acids (BAs) are regarded as the main components of bile. If there is a decreased or increased secretion of BAs, the composition of microbiota in the gut can change. Under normal physiological condition BAs fluctuates daily without causing any harm. Nevertheless, it is the long-term changes in bile acid secretion that can affect microbiota in the gut. If there is an increased excretion of AuNPs via hepatobiliary pathway it can alter bile formation. The aim of this study was to investigate whether the hepatobiliary excretion of AuNPs will alter the bile formation two weeks after intravenous administration of 14 nm AuNPs to Wistar rats. Rat liver samples of two previous experiments were used to investigate bile formation. The rats had been injected intravenously with a single dose of citrate capped and functionalised AuNPs. These rats were killed 14 days later. Small pieces of liver were stored in RNAlater. The mRNA of different enzymes and transporters in the hepatobiliary system were quantified in these samples and compared with suitable control. As a reference the mRNA of the same enzymes and transporters were extracted and quantified in rat liver that were killed one day after injection with one of the abovementioned functionalised AuNPs. The study shows down-regulation of genes responsible for conjugation of BAs whereas the rate-limiting enzymes were not significantly changed. This was the first study to investigate the formation of bile in relation to the use of AuNPs. The effect and consequences of AuNPs on the hepatobiliary system need further investigation.
- Full Text:
- Date Issued: 2019
A gatherer's paradise? Early humans and plant foraging on the cape south coast, South Africa
- Authors: Gummow, William Thomas
- Date: 2019
- Subjects: Soil amendments , Plants -- Nutrition Plant physiology
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/39687 , vital:35348
- Description: South Africa is a semi-arid country that is experiencing population growth and the associated pressure of producing sufficient crops to sustain the population. Furthermore, poor land management has also led to increased degradation of valuable arable land. To improve poor soil quality and possibly avoid or reverse degradation and ultimately desertification, it was suggested that soil amendments are a potential solution to some of these problems. Although soil amendment is a relatively well-known practice to improve soil quality, the use of rubber crumb as a soil amendment is not well studied. Rubber crumb is produced from end-of-life tyres that have been ground up to fine particles and as such can be used as a secondary resource to replace the use of virgin materials. Rubber crumb has been used in an array of industries, however, the present study investigated the possibility that rubber crumb might be used as a soil amendment to alleviate various forms of soil degradation, specifically soil compaction and crusting, and potentially improve crop establishment and growth.To determine this, a soil that is prone to crusting and compaction was amended with rubber crumb at rates of 5%, 15% and 25%. Various soil physical characteristics, such as bulk density, particle density, porosity, field capacity and penetration resistance were investigated and it was determined that as the percentage rubber crumb increases in the soil, so do the beneficial characteristics of the soil. Furthermore, the rubber crumb was also treated in various ways in order to determine how the treatments might affect the chemical properties of the soil, as well as the amount of zinc that is leached from the rubber crumb. It was found that washing the rubber with a weak acid or even water prior to adding it to the soil resulted in more desirable chemical condition compared to untreated rubber crumb. Lastly, maize (Zea mays L.) was used to determine whether amending soil with pre-treated rubber crumb in different percentages had an influence on the germination success and growth rate of maize. In terms of germination success, amending soil with rubber crumb does not seem to have a significant influence, however, growth rate decreased as the percentage rubber crumb increased, while treating the rubber with a weak acid or water prior to adding it to soil had the most positive effect on plant growth. It can therefore be concluded that rubber crumb amendment rates between 5% and 15% resulted in the most desirable soil physical properties and plant growth amongst the amendments. However the best plant growth was still seen in the control soil, to which no rubber crumb had been added.
- Full Text:
- Date Issued: 2019
- Authors: Gummow, William Thomas
- Date: 2019
- Subjects: Soil amendments , Plants -- Nutrition Plant physiology
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/39687 , vital:35348
- Description: South Africa is a semi-arid country that is experiencing population growth and the associated pressure of producing sufficient crops to sustain the population. Furthermore, poor land management has also led to increased degradation of valuable arable land. To improve poor soil quality and possibly avoid or reverse degradation and ultimately desertification, it was suggested that soil amendments are a potential solution to some of these problems. Although soil amendment is a relatively well-known practice to improve soil quality, the use of rubber crumb as a soil amendment is not well studied. Rubber crumb is produced from end-of-life tyres that have been ground up to fine particles and as such can be used as a secondary resource to replace the use of virgin materials. Rubber crumb has been used in an array of industries, however, the present study investigated the possibility that rubber crumb might be used as a soil amendment to alleviate various forms of soil degradation, specifically soil compaction and crusting, and potentially improve crop establishment and growth.To determine this, a soil that is prone to crusting and compaction was amended with rubber crumb at rates of 5%, 15% and 25%. Various soil physical characteristics, such as bulk density, particle density, porosity, field capacity and penetration resistance were investigated and it was determined that as the percentage rubber crumb increases in the soil, so do the beneficial characteristics of the soil. Furthermore, the rubber crumb was also treated in various ways in order to determine how the treatments might affect the chemical properties of the soil, as well as the amount of zinc that is leached from the rubber crumb. It was found that washing the rubber with a weak acid or even water prior to adding it to the soil resulted in more desirable chemical condition compared to untreated rubber crumb. Lastly, maize (Zea mays L.) was used to determine whether amending soil with pre-treated rubber crumb in different percentages had an influence on the germination success and growth rate of maize. In terms of germination success, amending soil with rubber crumb does not seem to have a significant influence, however, growth rate decreased as the percentage rubber crumb increased, while treating the rubber with a weak acid or water prior to adding it to soil had the most positive effect on plant growth. It can therefore be concluded that rubber crumb amendment rates between 5% and 15% resulted in the most desirable soil physical properties and plant growth amongst the amendments. However the best plant growth was still seen in the control soil, to which no rubber crumb had been added.
- Full Text:
- Date Issued: 2019
The medicinal chemistry of selected halogenated diketopiperazines CYCLO(CIS-PRO-4F-PRO) and CYCLO(L-PHE-4I-VAL)
- Authors: Dakada, Vuyokazi
- Date: 2019
- Subjects: Medicinal plants , Drug development Cells -- Effect of drugs on
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/39370 , vital:35221
- Description: Generally, peptides are selective and efficacious compounds; as a result, they are the best candidates for drug discovery and development. Most peptide-based drugs have been approved for clinical use. The 2,5-Diketopiperazines (DKPs), also known as cyclic dipeptides, are simple compounds which come from nature. Many DKPs are extracted from animals and plants. For example, cyclo(Proline(Pro)-Leucine(Leu)), cyclo(Proline-Valine(Val)), cyclo(Proline-Phenylalanine(Phe)) etc. In this study cyclo(cis-Proline(Pro)-4F-Proline(Pro)) and cyclo(L- Phenylalanine(Phe)-4I- Valine (Val)) were synthesized from their linear esters using a method modified by Milne et al. (1992). This method yielded good results. However, cyclo(L-Phe-4I-Val) degraded due to physicochemical stability attributes caused by hygroscopicity and photosensitivity. Quantitative analysis and evaluation of physicochemical properties of each dipeptide was achieved by using scanning electron microscopy, thermal analysis (differential scanning calorimetry and thermogravimetric analysis) and X-ray powder diffraction. To determine the purity of the cyclic dipeptide, high performance liquid chromatography and thin layer chromatography was used. The structural elucidation of the cyclic dipeptides was carried by employing infrared spectroscopy, mass spectrometry, nuclear magnetic resonance spectroscopy and, molecular modelling and computational chemistry. The aim of this research was to discover possible biological activity of cyclo(cis-Pro-4-F-Pro) and cyclo(L-Phe-4I-Val) with respect to their antimicrobial, anticancer, anti-diabetic and haematological effects. Cyclo(cis-Pro-4Fluoro-Pro) had no inhibitory effect on the antimicrobial strains tested, and cyclo(L-Phe-4Iodo-Val) could not be tested as the compound decomposed.
- Full Text:
- Date Issued: 2019
- Authors: Dakada, Vuyokazi
- Date: 2019
- Subjects: Medicinal plants , Drug development Cells -- Effect of drugs on
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/39370 , vital:35221
- Description: Generally, peptides are selective and efficacious compounds; as a result, they are the best candidates for drug discovery and development. Most peptide-based drugs have been approved for clinical use. The 2,5-Diketopiperazines (DKPs), also known as cyclic dipeptides, are simple compounds which come from nature. Many DKPs are extracted from animals and plants. For example, cyclo(Proline(Pro)-Leucine(Leu)), cyclo(Proline-Valine(Val)), cyclo(Proline-Phenylalanine(Phe)) etc. In this study cyclo(cis-Proline(Pro)-4F-Proline(Pro)) and cyclo(L- Phenylalanine(Phe)-4I- Valine (Val)) were synthesized from their linear esters using a method modified by Milne et al. (1992). This method yielded good results. However, cyclo(L-Phe-4I-Val) degraded due to physicochemical stability attributes caused by hygroscopicity and photosensitivity. Quantitative analysis and evaluation of physicochemical properties of each dipeptide was achieved by using scanning electron microscopy, thermal analysis (differential scanning calorimetry and thermogravimetric analysis) and X-ray powder diffraction. To determine the purity of the cyclic dipeptide, high performance liquid chromatography and thin layer chromatography was used. The structural elucidation of the cyclic dipeptides was carried by employing infrared spectroscopy, mass spectrometry, nuclear magnetic resonance spectroscopy and, molecular modelling and computational chemistry. The aim of this research was to discover possible biological activity of cyclo(cis-Pro-4-F-Pro) and cyclo(L-Phe-4I-Val) with respect to their antimicrobial, anticancer, anti-diabetic and haematological effects. Cyclo(cis-Pro-4Fluoro-Pro) had no inhibitory effect on the antimicrobial strains tested, and cyclo(L-Phe-4Iodo-Val) could not be tested as the compound decomposed.
- Full Text:
- Date Issued: 2019
The influence of hands-on chemistry experimental interventions on the attitudes of grade 9 learners toward natural science
- Authors: Swartbooi Tarryn Beatrix
- Date: 2019
- Subjects: Chemistry -- Study and teaching
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/44628 , vital:38168
- Description: The primary purpose of this research was to explore the influence that interactive, hands-on chemistry experiments may have on grade 9 learners’ attitudes toward Natural Sciences. A pragmatic research philosophy was used to best answer the research question which asked “Do hands-on chemistry interventions have a positive effect on grade 9 learners cognitive, affective and behavioural attitude toward Natural Sciences?” and explore the problem statement “The conducting of relevant hands-on chemistry experiments and demonstrations are expected to positively affect learners’ attitudes (cognitive, affective and behavioural), which would in turn motivate learners to further explore science, both in and outside of the classrooms and increase their interest”. The attitudes of learners were studied at two quintile-1 ranked schools both situated in lower socio-economic areas. The main findings that for cognitive attitude from the achievement tests were that Quintile-1 schools based in low socio-economic areas have similar cognitive attitude outcomes (pre-tests, post-tests) except for scientific language. In addition, according to multiple linear regression testing, the hands-on chemistry intervention group (test group) had a more uniform understanding of the scientific topic under study when compared to the traditionally taught group of learners (control group). Key findings from the survey and focus group for affective attitude (School A n=56 and School B n=14) showed that most of the learners responded that science interests them. They also responded that they wanted science club as a permanent fixture at their school and enjoyed doing experiments practically. Main findings for the behavioural attitudes from the focus group and survey were that hands on chemistry experiments motivated grade 9 learners to select Physical Sciences in grade 10 and it also encouraged them to want follow a career in science. From the survey responses it was inferred that learners’ behavioural attitude (BA) toward science was positively affected by science demonstrations and experiments.
- Full Text:
- Date Issued: 2019
- Authors: Swartbooi Tarryn Beatrix
- Date: 2019
- Subjects: Chemistry -- Study and teaching
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/44628 , vital:38168
- Description: The primary purpose of this research was to explore the influence that interactive, hands-on chemistry experiments may have on grade 9 learners’ attitudes toward Natural Sciences. A pragmatic research philosophy was used to best answer the research question which asked “Do hands-on chemistry interventions have a positive effect on grade 9 learners cognitive, affective and behavioural attitude toward Natural Sciences?” and explore the problem statement “The conducting of relevant hands-on chemistry experiments and demonstrations are expected to positively affect learners’ attitudes (cognitive, affective and behavioural), which would in turn motivate learners to further explore science, both in and outside of the classrooms and increase their interest”. The attitudes of learners were studied at two quintile-1 ranked schools both situated in lower socio-economic areas. The main findings that for cognitive attitude from the achievement tests were that Quintile-1 schools based in low socio-economic areas have similar cognitive attitude outcomes (pre-tests, post-tests) except for scientific language. In addition, according to multiple linear regression testing, the hands-on chemistry intervention group (test group) had a more uniform understanding of the scientific topic under study when compared to the traditionally taught group of learners (control group). Key findings from the survey and focus group for affective attitude (School A n=56 and School B n=14) showed that most of the learners responded that science interests them. They also responded that they wanted science club as a permanent fixture at their school and enjoyed doing experiments practically. Main findings for the behavioural attitudes from the focus group and survey were that hands on chemistry experiments motivated grade 9 learners to select Physical Sciences in grade 10 and it also encouraged them to want follow a career in science. From the survey responses it was inferred that learners’ behavioural attitude (BA) toward science was positively affected by science demonstrations and experiments.
- Full Text:
- Date Issued: 2019
Early Jurassic dolerites of the Karoo Large Igneous Province ( KLIP): an analysis of their age and emplacement history from sea level to the Drakensberg Mountains in the Eastern Cape , South Africa Submitted
- Authors: Muedi, Thomas Tshifhiwa
- Date: 2019
- Subjects: Geological time , Geochemistry Geology -- South Africa
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10948/41908 , vital:36608
- Description: South Africa hosts one of the largest Large Igneous Provinces (LIPs that is likely linked to the early separation of East and West Gondwana. However, despite many studies, the relationship between dolerites and volcanic basalts of this LIP (also known as the Karoo Large Igneous Province or KLIP) remains unsolved, because of poorly linked age dates (timing), geochemistry and emplacement mechanisms. This problem is in part because different unreliable dating techniques with large margin of errors have been applied This study aims to address these issues by performing new geo chemical and high resolution geochronological analyses on a number of dolerites (sills and dykes), volcanic s also referred to in the literature as the Drakensberg flood basalts) and samples from drill cores and field outcrops. This project is focused on dolerites in the Eastern Cape Province and provides results from field mapping of dolerites (sills and dykes) from the sea level to an elevation of circa 1350 metres above sea level (MASL) and their link to the volcanic in the Eastern Cape Province. The dolerite dykes observed trends from metres to hundreds of kilometres and cut across volcanic, which have similar geochemistry. The intrusive dolerites collected from the field and from d rill core samples were likely emplaced by magma infiltration through pre-existing sub vertical brittle fractures and fissures and then emplaced horizontally as sills circa 183 Ma Detailed fracture mapping across host rock to the dolerite was carried out to test if they acted as possible pathways for magmatic emplacements. The dolerite dykes and fractures mapped in the host sedimentary rocks have a dominant NW direction, especially towards volcanic basalts. The project provides tests based on the geochemical relationships of the dolerites and basalts from sixty-six (66) cores and field outcrop samples. The results confirm that the chemical analyses from the volcanic basalts an d dolerites are closely related and reveal that most samples are Ocean Island Basalt OIB), but some also reveal subduction related processes. This is consistent with models that suggest subduction along south west Gondwana may have influenced plumemagmatism derived from the lower mantle that initiated break up of this supercontinent e.g de Wit and Stern 1981 Storey et al , 1992 ; Torsvik et al., 2006 and Burke et al., 2008)
- Full Text:
- Date Issued: 2019
- Authors: Muedi, Thomas Tshifhiwa
- Date: 2019
- Subjects: Geological time , Geochemistry Geology -- South Africa
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10948/41908 , vital:36608
- Description: South Africa hosts one of the largest Large Igneous Provinces (LIPs that is likely linked to the early separation of East and West Gondwana. However, despite many studies, the relationship between dolerites and volcanic basalts of this LIP (also known as the Karoo Large Igneous Province or KLIP) remains unsolved, because of poorly linked age dates (timing), geochemistry and emplacement mechanisms. This problem is in part because different unreliable dating techniques with large margin of errors have been applied This study aims to address these issues by performing new geo chemical and high resolution geochronological analyses on a number of dolerites (sills and dykes), volcanic s also referred to in the literature as the Drakensberg flood basalts) and samples from drill cores and field outcrops. This project is focused on dolerites in the Eastern Cape Province and provides results from field mapping of dolerites (sills and dykes) from the sea level to an elevation of circa 1350 metres above sea level (MASL) and their link to the volcanic in the Eastern Cape Province. The dolerite dykes observed trends from metres to hundreds of kilometres and cut across volcanic, which have similar geochemistry. The intrusive dolerites collected from the field and from d rill core samples were likely emplaced by magma infiltration through pre-existing sub vertical brittle fractures and fissures and then emplaced horizontally as sills circa 183 Ma Detailed fracture mapping across host rock to the dolerite was carried out to test if they acted as possible pathways for magmatic emplacements. The dolerite dykes and fractures mapped in the host sedimentary rocks have a dominant NW direction, especially towards volcanic basalts. The project provides tests based on the geochemical relationships of the dolerites and basalts from sixty-six (66) cores and field outcrop samples. The results confirm that the chemical analyses from the volcanic basalts an d dolerites are closely related and reveal that most samples are Ocean Island Basalt OIB), but some also reveal subduction related processes. This is consistent with models that suggest subduction along south west Gondwana may have influenced plumemagmatism derived from the lower mantle that initiated break up of this supercontinent e.g de Wit and Stern 1981 Storey et al , 1992 ; Torsvik et al., 2006 and Burke et al., 2008)
- Full Text:
- Date Issued: 2019