Physical properties of solid-state erythromycin derived compounds
- Authors: Neglur, Rekha R
- Date: 2016
- Subjects: Erythromycin -- Thermal properties , Azithromycin -- Thermal properties
- Language: English
- Type: Thesis , Doctoral , DPhil
- Identifier: http://hdl.handle.net/10948/7228 , vital:21308
- Description: This thesis investigated the physical properties of the macrolide antibiotics: Erythromycin dihydrate (EM-DH), Roxithromycin monohydrate (RM-MH) and Azithromycin dihydrate (AZM-DH). The abovementioned hydrate compounds were investigated in terms of the hydrate-anhydrate crystal structure stability, dehydration and observed polymorphism under controlled temperature heating programs. Identified hydrate and anhydrate polymorphs were subjected to physical stability testing during controlled storage. EM-DH was characterized by thermal analysis (DSC, TGA), X-ray diffraction, FTIR and microscopy. Dehydration of EM-DH at temperatures of 100, 157 and 200°C (followed by supercooling to 25°C) produced the form (I) anhydrate (Tm =142.9°C), form (II) anhydrate (Tm = 184.7°C ) and amorph (II) (Tg = 118°C) respectively. The attempts to produce amorph (I) from melting (in vicinity of form (I) melt over temperature range 133°C to 144°C) and supercooling was unsuccessful due to the high crystallization tendency of the form (I) melt. Brief humidity exposure and controlled temperature (40°C)/ humidity storage for 4 days (0-96% RH) revealed hygroscopic behaviour for the anhydrate crystal (forms (I) and (II)) and amorph (II) forms. Form (II) converted to a nonstoichiometric hydrate where extent of water vapour absorption increased with increased storage humidity (2.1% absorbed moisture from recorded TGA at 96% RH). Amorph (II) exhibited similar trends but with greater water absorption of 4.7% (recorded with TGA) at 96% RH. The pulverization and sieving process of amorph (II) (at normal environmental conditions) was accompanied by some water vapour absorption (1.1%). A slightly lower absorbed moisture content of 3.3% (from TGA) after controlled 4 days storage at 40°C/ 96% RH was recorded. This suggested some physical instability (crystallization tendency) of amorph (II) after pulverization. The thermally induced dehydration of RM-MH by DSC-TG was evaluated structurally (SCXRD), morphologically (microscopy) and by kinetic analysis. Various kinetic analysis approaches were employed (advanced, approximation based integral and differential kinetic analysis methods) in order to obtain reliable dehydration kinetic parameters. The crystal structure was little affected by dehydration as most H-bonds were intramolecular and not integral to the crystal structure stability. Kinetic parameters from thermally stimulated dehydration indicated a multidimensional diffusion based mechanism, due to the escape of water from interlinked voids in crystal. The hygroscopicity of the forms RM-MH, Roxithromycin-anhydrate and amorph glass (Tg = 81.4°C) were investigated. Roxithromycinanhydrate (crystalline) converted readily to RM-MH which were found to be compositionally stable over the humidity range 43-96%RH. Amorphous glass exhibited increased water vapour absorption with increasing storage humidity (40°C/ 0-96% RH). TG analysis suggested a moisture content of 3.5% at 96% RH after 4 storage days. DSC and powder XRD analysis of stored pulverised amorphous glass indicated some physical instability due to water induced crystallization. Commercial AZM-DH and its modifications were characterized by thermal analysis (DSC, TGA), SC-XRD and microscopy. Thermally stimulated dehydration of AZM-DH occurred in a two-step process over different temperature ranges. This was attributed to different bonding environments for coordinated waters which were also verified from the crystal structure. Dehydration activation energies for thermally stimulated dehydration were however similar for both loss steps. This was attributed to similarities in the mode of H- bonding. Different forms of AZM were prepared by programmed temperature heating and cooling of AZM-DH. The prepared forms included amorphous glass (melt supercooling), amorphous powder (prepared below crystalline melting temperature), crystalline anhydrate and crystalline partial dehydrate. Humidity exposure indicated hygroscopic behaviour for the amorphous, crystalline anhydrate and crystalline partial dehydrate modifications. Both the crystalline anhydrate and partial dehydrate modifications converted to the stoichiometric dihydrate form (AZM-DH) at normal environmental conditions at ambient temperature. Both the amorph glass and amorph powder exhibited increased moisture absorption with increased humidity exposure. TG analysis of the pulverised amorph glass indicated a moisture content of 5.1% at 96% RH after 4 storage days. The absence of crystalline melt in DSC and presence of Tg (106.9°C) indicated the sample remained amorphous after pulverisation and storage for 4 days at 40°C/ 96% RH.
- Full Text:
- Date Issued: 2016
- Authors: Neglur, Rekha R
- Date: 2016
- Subjects: Erythromycin -- Thermal properties , Azithromycin -- Thermal properties
- Language: English
- Type: Thesis , Doctoral , DPhil
- Identifier: http://hdl.handle.net/10948/7228 , vital:21308
- Description: This thesis investigated the physical properties of the macrolide antibiotics: Erythromycin dihydrate (EM-DH), Roxithromycin monohydrate (RM-MH) and Azithromycin dihydrate (AZM-DH). The abovementioned hydrate compounds were investigated in terms of the hydrate-anhydrate crystal structure stability, dehydration and observed polymorphism under controlled temperature heating programs. Identified hydrate and anhydrate polymorphs were subjected to physical stability testing during controlled storage. EM-DH was characterized by thermal analysis (DSC, TGA), X-ray diffraction, FTIR and microscopy. Dehydration of EM-DH at temperatures of 100, 157 and 200°C (followed by supercooling to 25°C) produced the form (I) anhydrate (Tm =142.9°C), form (II) anhydrate (Tm = 184.7°C ) and amorph (II) (Tg = 118°C) respectively. The attempts to produce amorph (I) from melting (in vicinity of form (I) melt over temperature range 133°C to 144°C) and supercooling was unsuccessful due to the high crystallization tendency of the form (I) melt. Brief humidity exposure and controlled temperature (40°C)/ humidity storage for 4 days (0-96% RH) revealed hygroscopic behaviour for the anhydrate crystal (forms (I) and (II)) and amorph (II) forms. Form (II) converted to a nonstoichiometric hydrate where extent of water vapour absorption increased with increased storage humidity (2.1% absorbed moisture from recorded TGA at 96% RH). Amorph (II) exhibited similar trends but with greater water absorption of 4.7% (recorded with TGA) at 96% RH. The pulverization and sieving process of amorph (II) (at normal environmental conditions) was accompanied by some water vapour absorption (1.1%). A slightly lower absorbed moisture content of 3.3% (from TGA) after controlled 4 days storage at 40°C/ 96% RH was recorded. This suggested some physical instability (crystallization tendency) of amorph (II) after pulverization. The thermally induced dehydration of RM-MH by DSC-TG was evaluated structurally (SCXRD), morphologically (microscopy) and by kinetic analysis. Various kinetic analysis approaches were employed (advanced, approximation based integral and differential kinetic analysis methods) in order to obtain reliable dehydration kinetic parameters. The crystal structure was little affected by dehydration as most H-bonds were intramolecular and not integral to the crystal structure stability. Kinetic parameters from thermally stimulated dehydration indicated a multidimensional diffusion based mechanism, due to the escape of water from interlinked voids in crystal. The hygroscopicity of the forms RM-MH, Roxithromycin-anhydrate and amorph glass (Tg = 81.4°C) were investigated. Roxithromycinanhydrate (crystalline) converted readily to RM-MH which were found to be compositionally stable over the humidity range 43-96%RH. Amorphous glass exhibited increased water vapour absorption with increasing storage humidity (40°C/ 0-96% RH). TG analysis suggested a moisture content of 3.5% at 96% RH after 4 storage days. DSC and powder XRD analysis of stored pulverised amorphous glass indicated some physical instability due to water induced crystallization. Commercial AZM-DH and its modifications were characterized by thermal analysis (DSC, TGA), SC-XRD and microscopy. Thermally stimulated dehydration of AZM-DH occurred in a two-step process over different temperature ranges. This was attributed to different bonding environments for coordinated waters which were also verified from the crystal structure. Dehydration activation energies for thermally stimulated dehydration were however similar for both loss steps. This was attributed to similarities in the mode of H- bonding. Different forms of AZM were prepared by programmed temperature heating and cooling of AZM-DH. The prepared forms included amorphous glass (melt supercooling), amorphous powder (prepared below crystalline melting temperature), crystalline anhydrate and crystalline partial dehydrate. Humidity exposure indicated hygroscopic behaviour for the amorphous, crystalline anhydrate and crystalline partial dehydrate modifications. Both the crystalline anhydrate and partial dehydrate modifications converted to the stoichiometric dihydrate form (AZM-DH) at normal environmental conditions at ambient temperature. Both the amorph glass and amorph powder exhibited increased moisture absorption with increased humidity exposure. TG analysis of the pulverised amorph glass indicated a moisture content of 5.1% at 96% RH after 4 storage days. The absence of crystalline melt in DSC and presence of Tg (106.9°C) indicated the sample remained amorphous after pulverisation and storage for 4 days at 40°C/ 96% RH.
- Full Text:
- Date Issued: 2016
Population, communication and habitat comparisons between the major gummivorous strepsirhines of Madagascar (phaner) and Cameroon (euoticus)
- Authors: Forbanka, Derick Nomuh
- Date: 2016
- Subjects: Adaptation (Biology) , Mammals -- Evolution , Mammals -- Behavior
- Language: English
- Type: Thesis , Doctoral , Zoology
- Identifier: http://hdl.handle.net/10353/15957 , vital:40567
- Description: The suborder Strepsirhini contains a large proportion of the living gummivorous mammal taxa, and includes two genera of specialist gummivores, Euoticus and Phaner, which present particularly interesting cases of convergent adaptive evolution in Africa and Madagascar, respectively. Although these genera are not closely related, they share several anatomical, behavioural and physiological specialisations associated with their diets, and despite their biogeographical separation, there seems to be substantial coincidence in their habitats and habits. Neither the ecology nor the systematics of Phaner and Euoticus has been the subject of much detailed research, and little is known of the conservation status of the genera. Even their specific diversity is unresolved. In this study I investigated and compared aspects of their ecology at both a macro-and a microhabitat scale, including wild populations of all groups within the two genera that have been accorded species status in recent field guides and systematic reviews. I also studied aspects of their social communication behaviour as clues to their species-level diversity. Species and their formation (or speciation) have inspired a great deal of evolutionary research, but remain contentious issues in evolutionary biology. This is due both to the difficulties inherent in inferring the details of a dynamic biological process that occurred over some time in the past from the recent, relatively static patterns of variation observed, as well as the limited consensus among biologists in identifying such patterns. It is therefore important to distinguish the kinds of patterns in nature that are predicted by different views of species and speciation, and also to see how well these predictions fare when applied to the speciation patterns found in strepsirhine primates. Theories of speciation cannot be separated from species concepts, and one concept widely supported in primatology is the Recognition Concept of species because of its heuristic nature. The Recognition Concept is based on Specific-mate Recognition Systems (SMRS). I focussed on SMRS features of Euoticus and Phaner, loud call specificity, and species’ preferred habitats. My results provided some support for the distinctiveness of currently identified species, although this was not clear-cut. Population densities of both Phaner and Euoticus appear to have declined in recent years, even though both Phaner and Euoticus appear to be well adapted to both primary and secondary forest, and exhibit ecological plasticity. Statistically some loud call parameters vary among the putative species of the genus Phaner and not Euoticus. Phaner pallescens at Kirindy, Madasgascar was clearly able to discriminate loud calls of its own population from other proposed species within the genus. Most loud call parameters did not show any statistical degradation with increasing distance. A crucial finding of my study was that the two lineages are not only convergent in terms of dietary and locomotor aspects of their ecology, but also in the structures of their loud calls. The environmental adaptation of communication systems is often overlooked when studying adaptive convergence, but my study indicates that acoustic properties are a crucial aspect of a species’ preferred habitat. The results of this study can be used to improve conservation planning, and also add to our understanding of the evolutionary history of strepsirhine primates.
- Full Text:
- Date Issued: 2016
- Authors: Forbanka, Derick Nomuh
- Date: 2016
- Subjects: Adaptation (Biology) , Mammals -- Evolution , Mammals -- Behavior
- Language: English
- Type: Thesis , Doctoral , Zoology
- Identifier: http://hdl.handle.net/10353/15957 , vital:40567
- Description: The suborder Strepsirhini contains a large proportion of the living gummivorous mammal taxa, and includes two genera of specialist gummivores, Euoticus and Phaner, which present particularly interesting cases of convergent adaptive evolution in Africa and Madagascar, respectively. Although these genera are not closely related, they share several anatomical, behavioural and physiological specialisations associated with their diets, and despite their biogeographical separation, there seems to be substantial coincidence in their habitats and habits. Neither the ecology nor the systematics of Phaner and Euoticus has been the subject of much detailed research, and little is known of the conservation status of the genera. Even their specific diversity is unresolved. In this study I investigated and compared aspects of their ecology at both a macro-and a microhabitat scale, including wild populations of all groups within the two genera that have been accorded species status in recent field guides and systematic reviews. I also studied aspects of their social communication behaviour as clues to their species-level diversity. Species and their formation (or speciation) have inspired a great deal of evolutionary research, but remain contentious issues in evolutionary biology. This is due both to the difficulties inherent in inferring the details of a dynamic biological process that occurred over some time in the past from the recent, relatively static patterns of variation observed, as well as the limited consensus among biologists in identifying such patterns. It is therefore important to distinguish the kinds of patterns in nature that are predicted by different views of species and speciation, and also to see how well these predictions fare when applied to the speciation patterns found in strepsirhine primates. Theories of speciation cannot be separated from species concepts, and one concept widely supported in primatology is the Recognition Concept of species because of its heuristic nature. The Recognition Concept is based on Specific-mate Recognition Systems (SMRS). I focussed on SMRS features of Euoticus and Phaner, loud call specificity, and species’ preferred habitats. My results provided some support for the distinctiveness of currently identified species, although this was not clear-cut. Population densities of both Phaner and Euoticus appear to have declined in recent years, even though both Phaner and Euoticus appear to be well adapted to both primary and secondary forest, and exhibit ecological plasticity. Statistically some loud call parameters vary among the putative species of the genus Phaner and not Euoticus. Phaner pallescens at Kirindy, Madasgascar was clearly able to discriminate loud calls of its own population from other proposed species within the genus. Most loud call parameters did not show any statistical degradation with increasing distance. A crucial finding of my study was that the two lineages are not only convergent in terms of dietary and locomotor aspects of their ecology, but also in the structures of their loud calls. The environmental adaptation of communication systems is often overlooked when studying adaptive convergence, but my study indicates that acoustic properties are a crucial aspect of a species’ preferred habitat. The results of this study can be used to improve conservation planning, and also add to our understanding of the evolutionary history of strepsirhine primates.
- Full Text:
- Date Issued: 2016
Predators of aerial insects and riparian cross-boundary trophic dynamics: web-building spiders, dragonflies and damselflies
- Authors: Chari, Lenin Dzibakwe
- Date: 2016
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/55791 , vital:26734
- Description: This thesis characterises the cross-boundary trophic interactions of a relatively small model ecosystem, the Kowie River (Eastern Cape of South Africa), to explore their epistemic implications for systems ecology. Using web-building spiders and odonates (dragonflies and damselflies) as model organisms, I sought to investigate whether the diets of predators of aerial insects could be used to assess the strength of the trophic connectivity between freshwater and terrestrial systems in relation to variables such as stream width, distance from the river and aquatic insect emergence rates and abundances. Predator diet composition was determined by using a combination of diet analysis tools: direct observations of cross-subsidies, naturally-abundant stable (carbon and nitrogen) isotope analysis and fatty acid analysis. I also sought to reveal feeding niches and guilds among riparian aerial predators and investigate how the environment influenced predators’ access to aquatic prey subsidies. As emergent aquatic insect abundances decreased with an increase in distance from the river, and increased with stream width and seasonal changes from winter to summer, stable isotope and fatty acid analyses revealed distinct changes in web-building spider diet composition. Examination of the fatty acid eicosapentaenoic acid, a component commonly used as an indicator of consumer reliance on aquatic nutritional subsidies, showed that aquatic subsidies extended further inland at the wider sections of the river. Spiders and odonates at the wider sections of the Kowie River generally received more subsidies (56 – 70%) than those at the narrower sections (25 – 60%). When terrestrial insect biomass was distinctly low in winter, the benefit of aquatic subsidisation to spiders was relatively lower at the narrower sections of the Kowie River relative to the wide sections. As such, riparian areas adjacent to wide parts of the river were more likely to support larger populations of aerial predators than those at the narrow sections. Apart from the diet changes across time and space, there was evidence of inter-specific niche partitioning in both spiders and odonates, but no differences were observed between males and females of the same species. Results showed odonates of different sizes and hunting strategies had separate dietary niches, hence varied access to aquatic nutritional subsidies. The larger odonate taxa that frequently foraged mid-air had more varied diets and relied less on aquatic emergent insects than the smaller odonates that foraged from perches near the river. There was also evidence of niche partitioning amongst the spiders, as those that built horizontal webs captured more aquatic insects (40 – 78%) than the vertical orb-web builders (20 – 66%). This study showed that the nature and extent of trophic cross-boundary linkages in riparian areas largely depended on the availability of subsidies that varied seasonally and spatially. The width of the stream and seasonal variability emerged as important predictors of emergent insect abundances/biomasses that influenced predator feeding niches. The high mobility of odonates made their reliance on aquatic nutritional subsidies different from the less mobile spiders. The link between the width of the river and the extent of trophic connectivity has implications for riparian area management and definition of riparian buffer zones. However, the variation in diet niches amongst terrestrial consumers makes the results area-specific, and more studies are required that incorporate additional terrestrial predators in other fluvial systems so that we can make some generalizations on the dynamics of riparian trophic cross-boundary links.
- Full Text:
- Date Issued: 2016
- Authors: Chari, Lenin Dzibakwe
- Date: 2016
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/55791 , vital:26734
- Description: This thesis characterises the cross-boundary trophic interactions of a relatively small model ecosystem, the Kowie River (Eastern Cape of South Africa), to explore their epistemic implications for systems ecology. Using web-building spiders and odonates (dragonflies and damselflies) as model organisms, I sought to investigate whether the diets of predators of aerial insects could be used to assess the strength of the trophic connectivity between freshwater and terrestrial systems in relation to variables such as stream width, distance from the river and aquatic insect emergence rates and abundances. Predator diet composition was determined by using a combination of diet analysis tools: direct observations of cross-subsidies, naturally-abundant stable (carbon and nitrogen) isotope analysis and fatty acid analysis. I also sought to reveal feeding niches and guilds among riparian aerial predators and investigate how the environment influenced predators’ access to aquatic prey subsidies. As emergent aquatic insect abundances decreased with an increase in distance from the river, and increased with stream width and seasonal changes from winter to summer, stable isotope and fatty acid analyses revealed distinct changes in web-building spider diet composition. Examination of the fatty acid eicosapentaenoic acid, a component commonly used as an indicator of consumer reliance on aquatic nutritional subsidies, showed that aquatic subsidies extended further inland at the wider sections of the river. Spiders and odonates at the wider sections of the Kowie River generally received more subsidies (56 – 70%) than those at the narrower sections (25 – 60%). When terrestrial insect biomass was distinctly low in winter, the benefit of aquatic subsidisation to spiders was relatively lower at the narrower sections of the Kowie River relative to the wide sections. As such, riparian areas adjacent to wide parts of the river were more likely to support larger populations of aerial predators than those at the narrow sections. Apart from the diet changes across time and space, there was evidence of inter-specific niche partitioning in both spiders and odonates, but no differences were observed between males and females of the same species. Results showed odonates of different sizes and hunting strategies had separate dietary niches, hence varied access to aquatic nutritional subsidies. The larger odonate taxa that frequently foraged mid-air had more varied diets and relied less on aquatic emergent insects than the smaller odonates that foraged from perches near the river. There was also evidence of niche partitioning amongst the spiders, as those that built horizontal webs captured more aquatic insects (40 – 78%) than the vertical orb-web builders (20 – 66%). This study showed that the nature and extent of trophic cross-boundary linkages in riparian areas largely depended on the availability of subsidies that varied seasonally and spatially. The width of the stream and seasonal variability emerged as important predictors of emergent insect abundances/biomasses that influenced predator feeding niches. The high mobility of odonates made their reliance on aquatic nutritional subsidies different from the less mobile spiders. The link between the width of the river and the extent of trophic connectivity has implications for riparian area management and definition of riparian buffer zones. However, the variation in diet niches amongst terrestrial consumers makes the results area-specific, and more studies are required that incorporate additional terrestrial predators in other fluvial systems so that we can make some generalizations on the dynamics of riparian trophic cross-boundary links.
- Full Text:
- Date Issued: 2016
Preparation and application of plasmon metal enhanced titanium dioxide photocatalyst for the removal of organics in water
- Authors: Nyamukamba, Pardon
- Date: 2016
- Subjects: Water -- Purification -- Photocatalysis Titanium dioxide Water chemistry
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10353/2765 , vital:28074
- Description: Advanced oxidation processes are capable of removing organic compounds that cannot be removed by conventional water treatment methods. Among the oxidation processes, photo-catalysis using titanium dioxide (TiO2) is a promising method but suffers from rapid electron-hole recombination rates and only absorbs UV light which is a small percentage (5 percent) of the total solar radiation. Therefore there is a need to reduce the recombination rates and also extend the absorption of the photo-catalyst into the visible region which constitutes 55 percent of the total solar radiation. The major aims of this study were to prepare plasmon metal decorated and doped TiO2 photo-catalysts immobilized on quartz substrates and test their photo-catalytic and antimicrobial activities. The effect of film thickness (loading) and use of different shapes of plasmon metal nanostructures was investigated. TiO2 thin films were prepared by a sputter coating technique while plasmon metal (Au & Ag)/carbon co-doped TiO2 by a simple sol gel process and plasmon metal films were prepared by the thermal evaporation technique. Different plasmon metal nanostructures (nanorods, dendrites, nanowires and spherical nanoparticles) were prepared using a wet chemical technique using sodium borohydride as the reducing agent. Nanocomposites of co-doped TiO2 photo-catalyst and plasmon elements of different proportions were also prepared. The prepared photo-catalysts were coated onto etched and MPTMS (3-Mercaptopropyl trimethoxysliane) treated quartz glass substrate which is a stable support favouring easy recovery. The prepared materials were characterized by XRD, HRTEM, TEM, HRSEM, FT-IR, SEM, PIXE and TGA while the doped TiO2 was characterized by XPS, BET, CHNS and Raman Spectroscopy. The effect of pH of solution, presence of other contaminants and salts in solution, initial concentration of the model pollutant and type of the plasmonic elements on the photocatalytic activity of TiO2 towards 4-(4-sulfophenylazo)-N,N-dimethyl aniline (methyl orange) were also investigated. The selected TiO2 photo-catalyst films were tested for antimicrobial properties. The effect of different types of plasmon elements on the antimicrobial activity of TiO2 against E. coli ATCC 3695 was evaluated under both sunlight and weak UV light. Under UV light, Ag showed the highest enhancement in photo-catalytic activity of TiO2 than Au and Cu. The photo-catalytic activity of TiO2 increased with an increase in Ag content to an optimum loading and then started to decrease with a further increase in loading. For Cu and Au, photo-activity activity increased with an increase in plasmon metal content. Under sunlight, Cu showed the highest enhancement of TiO2 photocatalytic compared to Ag and Au. The change in order of deposition showed that Au films enhanced the photo-activity better when they were deposited underneath rather than on top of TiO2 on quartz supports but Ag films performed better in enhancing photo-activity when they were deposited on top of TiO2. The use of bimetallic layers and three layer systems of different plasmon elements enhanced photo-catalytic activity better than the use of a monometallic layer. The presence of other organic contaminants and salts in solutions was found to reduce the photo-degradation of methyl orange due to preferential adsorption of other contaminants. When the pH was increased, the photocatalytic activity of TiO2 towards methyl orange was reduced. In antimicrobial studies, it was found that the plasmon elements greatly improved the antibacterial action of TiO2 against Escherichia coli ATCC 3695 in water and the best antibacterial action was observed with silver/carbon co-doped TiO2 photo-catalyst under sunlight The doped samples consisted of polydisperse nanoparticles which were found to be beneficial for photo-catalytic activity enhancement under sunlight.
- Full Text:
- Date Issued: 2016
- Authors: Nyamukamba, Pardon
- Date: 2016
- Subjects: Water -- Purification -- Photocatalysis Titanium dioxide Water chemistry
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10353/2765 , vital:28074
- Description: Advanced oxidation processes are capable of removing organic compounds that cannot be removed by conventional water treatment methods. Among the oxidation processes, photo-catalysis using titanium dioxide (TiO2) is a promising method but suffers from rapid electron-hole recombination rates and only absorbs UV light which is a small percentage (5 percent) of the total solar radiation. Therefore there is a need to reduce the recombination rates and also extend the absorption of the photo-catalyst into the visible region which constitutes 55 percent of the total solar radiation. The major aims of this study were to prepare plasmon metal decorated and doped TiO2 photo-catalysts immobilized on quartz substrates and test their photo-catalytic and antimicrobial activities. The effect of film thickness (loading) and use of different shapes of plasmon metal nanostructures was investigated. TiO2 thin films were prepared by a sputter coating technique while plasmon metal (Au & Ag)/carbon co-doped TiO2 by a simple sol gel process and plasmon metal films were prepared by the thermal evaporation technique. Different plasmon metal nanostructures (nanorods, dendrites, nanowires and spherical nanoparticles) were prepared using a wet chemical technique using sodium borohydride as the reducing agent. Nanocomposites of co-doped TiO2 photo-catalyst and plasmon elements of different proportions were also prepared. The prepared photo-catalysts were coated onto etched and MPTMS (3-Mercaptopropyl trimethoxysliane) treated quartz glass substrate which is a stable support favouring easy recovery. The prepared materials were characterized by XRD, HRTEM, TEM, HRSEM, FT-IR, SEM, PIXE and TGA while the doped TiO2 was characterized by XPS, BET, CHNS and Raman Spectroscopy. The effect of pH of solution, presence of other contaminants and salts in solution, initial concentration of the model pollutant and type of the plasmonic elements on the photocatalytic activity of TiO2 towards 4-(4-sulfophenylazo)-N,N-dimethyl aniline (methyl orange) were also investigated. The selected TiO2 photo-catalyst films were tested for antimicrobial properties. The effect of different types of plasmon elements on the antimicrobial activity of TiO2 against E. coli ATCC 3695 was evaluated under both sunlight and weak UV light. Under UV light, Ag showed the highest enhancement in photo-catalytic activity of TiO2 than Au and Cu. The photo-catalytic activity of TiO2 increased with an increase in Ag content to an optimum loading and then started to decrease with a further increase in loading. For Cu and Au, photo-activity activity increased with an increase in plasmon metal content. Under sunlight, Cu showed the highest enhancement of TiO2 photocatalytic compared to Ag and Au. The change in order of deposition showed that Au films enhanced the photo-activity better when they were deposited underneath rather than on top of TiO2 on quartz supports but Ag films performed better in enhancing photo-activity when they were deposited on top of TiO2. The use of bimetallic layers and three layer systems of different plasmon elements enhanced photo-catalytic activity better than the use of a monometallic layer. The presence of other organic contaminants and salts in solutions was found to reduce the photo-degradation of methyl orange due to preferential adsorption of other contaminants. When the pH was increased, the photocatalytic activity of TiO2 towards methyl orange was reduced. In antimicrobial studies, it was found that the plasmon elements greatly improved the antibacterial action of TiO2 against Escherichia coli ATCC 3695 in water and the best antibacterial action was observed with silver/carbon co-doped TiO2 photo-catalyst under sunlight The doped samples consisted of polydisperse nanoparticles which were found to be beneficial for photo-catalytic activity enhancement under sunlight.
- Full Text:
- Date Issued: 2016
Professional identity of teacher educators as assessors of teaching practice : a case study in a South African university
- Authors: Roy, Irene Juanita Sass
- Date: 2016
- Subjects: Teacher educators--Professional relationships Teachers--Training of
- Language: English
- Type: Thesis , Doctoral , Education
- Identifier: http://hdl.handle.net/10353/15969 , vital:40570
- Description: This study focuses on the professional identity of Teacher Educators as assessors of teaching practice for Post Graduate Certificate in Education (PGCE) student teachers.The research was presented as a case study at one institution of higher learning. The focus was on the professional identity of teacher educators as revealed in the assessment narratives they expressed as a report back to PGCE students and the verbalisation of their beliefs through semi-structured interviews at the particular institution. This study adopted a qualitative research methodology from an interpretivist paradigm whereby the collected data was coded and analysed through applying both inductive and deductive reasoning. Themes which emerged from the data were qualitatively analysed through the social-constructivist theories of Bernstein, Lave and Wenger and Feiman-Nemser. This study revealed that the professional identity of Teacher Educators plays a significant role in the way in which they assess students. The study showed that theprofessional identity (encompassing of professional knowledge) of Teacher Educators determines their assessment focus, professional knowledge and identity is reflected in the narrative feedback to PGCE student teachers and their views of the current assessment instrument as (in)effective. The study revealed that Teacher Educators have specific expectations (pedagogical skill, subject and content knowledge) but the complexities of their identity override how they apply the assessment instrument. In addition Teacher Educators are challenged by the PGCE cohort in that they expect this group to show the same competencies as students coming through the under-graduate programme. The study recommends that a collaborative approach be adopted in the preparation and assessment of PGCE student teachers; a re-conceptualisation of the requirements of teaching competence for this group be undertaken; and Teacher Educators be empowered to teach and assess PGCE student teachers aligned with the principles of andragogy and that Higher Education policy take cognisance of and make provision for the unique needs of PGCE teacher training. The study proposes a revised approach by Teacher Educators be considered which treat the assessment of teaching competence for PGCE student teachers in a less fragmented and individualised manner. This implies that a different organisational assessment culture is needed in order to democratize the assessment of PGCE student teachers, training in the GET band in South Africa.
- Full Text:
- Date Issued: 2016
- Authors: Roy, Irene Juanita Sass
- Date: 2016
- Subjects: Teacher educators--Professional relationships Teachers--Training of
- Language: English
- Type: Thesis , Doctoral , Education
- Identifier: http://hdl.handle.net/10353/15969 , vital:40570
- Description: This study focuses on the professional identity of Teacher Educators as assessors of teaching practice for Post Graduate Certificate in Education (PGCE) student teachers.The research was presented as a case study at one institution of higher learning. The focus was on the professional identity of teacher educators as revealed in the assessment narratives they expressed as a report back to PGCE students and the verbalisation of their beliefs through semi-structured interviews at the particular institution. This study adopted a qualitative research methodology from an interpretivist paradigm whereby the collected data was coded and analysed through applying both inductive and deductive reasoning. Themes which emerged from the data were qualitatively analysed through the social-constructivist theories of Bernstein, Lave and Wenger and Feiman-Nemser. This study revealed that the professional identity of Teacher Educators plays a significant role in the way in which they assess students. The study showed that theprofessional identity (encompassing of professional knowledge) of Teacher Educators determines their assessment focus, professional knowledge and identity is reflected in the narrative feedback to PGCE student teachers and their views of the current assessment instrument as (in)effective. The study revealed that Teacher Educators have specific expectations (pedagogical skill, subject and content knowledge) but the complexities of their identity override how they apply the assessment instrument. In addition Teacher Educators are challenged by the PGCE cohort in that they expect this group to show the same competencies as students coming through the under-graduate programme. The study recommends that a collaborative approach be adopted in the preparation and assessment of PGCE student teachers; a re-conceptualisation of the requirements of teaching competence for this group be undertaken; and Teacher Educators be empowered to teach and assess PGCE student teachers aligned with the principles of andragogy and that Higher Education policy take cognisance of and make provision for the unique needs of PGCE teacher training. The study proposes a revised approach by Teacher Educators be considered which treat the assessment of teaching competence for PGCE student teachers in a less fragmented and individualised manner. This implies that a different organisational assessment culture is needed in order to democratize the assessment of PGCE student teachers, training in the GET band in South Africa.
- Full Text:
- Date Issued: 2016
Relationships between cash management and growth of informal businesses in Uganda
- Nuwagaba, Geoffrey, Struwig, Miemie
- Authors: Nuwagaba, Geoffrey , Struwig, Miemie
- Date: 2016
- Subjects: Cash management -- Uganda , Informal sector (Economics) -- Uganda , Small business -- Uganda
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10948/12319 , vital:27054
- Description: This study investigates the relationships between cash management and growth of informal businesses in Uganda. Whereas anecdotal evidence has for some time revealed that informal businesses in Uganda are faced with the challenge of cash management, no specific studies have been conducted to investigate how this relates to the growth of businesses where evidence has also indicated that most of these businesses do not exist for very long. In particular, the study assesses and explores the growth levels of informal businesses in terms of sales volume, growth in employment and length of existence. The study investigates the various ways in which informal businesses manage their cash and investigates the various internal and external factors that moderate cash management and the growth of the informal businesses. Furthermore, the study proposes a possible framework to manage cash in informal businesses and makes recommendations to informal business owners and managers on how to effectively manage cash in order to stimulate business growth. In order to investigate the relationships between the variables, an empirical investigation was undertaken. Based on the literature review, the primary objective of the study was formulated to investigate the relationships between cash management and growth of informal businesses amidst the external and internal environment in Uganda in order to suggest a framework for effective management of cash by informal businesses that would enhance their growth. A positivistic research paradigm was adopted in this study. A sample of 383 informal businesses was drawn from the five divisions of Kampala district namely; Central, Kawempe, Makindye, Nakawa and Rubaga. To ensure validity and reliability, EFA and Cronbach’s alpha coefficient were computed. Six hypotheses were developed to test the relationships between cash management and growth of informal businesses. The empirical results revealed that there is a significant relationship between cash management and the external environment in which informal businesses operate, a significant relationship between the external environment and the growth of informal businesses and a significant relationship between cash management and growth of informal businesses where the external environment will have a moderating influence on the relationship. The empirical results did not establish a significant relationship between cash management and the internal environment in which informal businesses operate, the internal environment and growth of informal businesses and cash management and growth of informal businesses where internal environment will have a moderating influence on the relationship. The results of this study show that the growth of informal businesses is largely hampered by poor cash management practices and challenges such as the lack of cash planning, lack of cash forecasting and budgeting, lack of financial controls and reporting, the tendency to invest largely in short-term assets which limits their profitability, the employment of less competent and skilled staff and lack of formal accounting information systems. The magnitude of the impact of these is accelerated by the external environment such as competition and the legal and regulatory environment which put pressure on the little cash resources owned by these businesses. Based on the study results, several strategies based on individual cash components of cash planning, cash forecasting and budgeting, financial controls and reporting, short-term investment of cash surplus, competence and skills of staff and accounting information systems were recommended for implementation. It was further recommended that these strategies should be implemented while giving due attention to the external environment if informal businesses are to effectively manage cash and enhance their growth.
- Full Text:
- Date Issued: 2016
- Authors: Nuwagaba, Geoffrey , Struwig, Miemie
- Date: 2016
- Subjects: Cash management -- Uganda , Informal sector (Economics) -- Uganda , Small business -- Uganda
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10948/12319 , vital:27054
- Description: This study investigates the relationships between cash management and growth of informal businesses in Uganda. Whereas anecdotal evidence has for some time revealed that informal businesses in Uganda are faced with the challenge of cash management, no specific studies have been conducted to investigate how this relates to the growth of businesses where evidence has also indicated that most of these businesses do not exist for very long. In particular, the study assesses and explores the growth levels of informal businesses in terms of sales volume, growth in employment and length of existence. The study investigates the various ways in which informal businesses manage their cash and investigates the various internal and external factors that moderate cash management and the growth of the informal businesses. Furthermore, the study proposes a possible framework to manage cash in informal businesses and makes recommendations to informal business owners and managers on how to effectively manage cash in order to stimulate business growth. In order to investigate the relationships between the variables, an empirical investigation was undertaken. Based on the literature review, the primary objective of the study was formulated to investigate the relationships between cash management and growth of informal businesses amidst the external and internal environment in Uganda in order to suggest a framework for effective management of cash by informal businesses that would enhance their growth. A positivistic research paradigm was adopted in this study. A sample of 383 informal businesses was drawn from the five divisions of Kampala district namely; Central, Kawempe, Makindye, Nakawa and Rubaga. To ensure validity and reliability, EFA and Cronbach’s alpha coefficient were computed. Six hypotheses were developed to test the relationships between cash management and growth of informal businesses. The empirical results revealed that there is a significant relationship between cash management and the external environment in which informal businesses operate, a significant relationship between the external environment and the growth of informal businesses and a significant relationship between cash management and growth of informal businesses where the external environment will have a moderating influence on the relationship. The empirical results did not establish a significant relationship between cash management and the internal environment in which informal businesses operate, the internal environment and growth of informal businesses and cash management and growth of informal businesses where internal environment will have a moderating influence on the relationship. The results of this study show that the growth of informal businesses is largely hampered by poor cash management practices and challenges such as the lack of cash planning, lack of cash forecasting and budgeting, lack of financial controls and reporting, the tendency to invest largely in short-term assets which limits their profitability, the employment of less competent and skilled staff and lack of formal accounting information systems. The magnitude of the impact of these is accelerated by the external environment such as competition and the legal and regulatory environment which put pressure on the little cash resources owned by these businesses. Based on the study results, several strategies based on individual cash components of cash planning, cash forecasting and budgeting, financial controls and reporting, short-term investment of cash surplus, competence and skills of staff and accounting information systems were recommended for implementation. It was further recommended that these strategies should be implemented while giving due attention to the external environment if informal businesses are to effectively manage cash and enhance their growth.
- Full Text:
- Date Issued: 2016
Research as hope intervention: a visual participatory study with rural South African school children
- Authors: Cherrington, Avivit Miriam
- Date: 2016
- Subjects: Affective education -- South Africa , Critical pedagogy -- South Africa , Hope -- Social aspects -- South Africa
- Language: English
- Type: Thesis , Doctoral , PhD (Education)
- Identifier: http://hdl.handle.net/10948/8350 , vital:26348
- Description: There is a dearth of knowledge on rural South African children’s perspectives of hope, and how their hope can be nurtured, shaped, and strengthened. Guided by a qualitative approach, and located within a critical transformative paradigm, this study explores the following research question: How could visual participatory methodology as ‘research as intervention’ enable rural South African primary school children to explore their conceptualisations of hope, as well as strengthen their hope? To answer this question I pose two sub-questions: Firstly, what are rural primary school children’s conceptualisations of hope? Secondly, how could using visual participatory methodology to explore their hope also strengthen the children’s hope? Hope plays a key role in the lives of people, influencing decisions and behaviour, as well as coping skills and wellbeing. The socio-economic and cultural contexts in which rural South African children find themselves are critical in enabling hope and influencing their psychosocial wellbeing. While international hope research boasts a diversity of theories, there is scarce representation of such research from an African perspective. Unable to turn to an Afrocentric theory of hope this study is framed by two theories from the global-North: Scioli’s (2007) Integrative theory of hope which provides a description of the individual’s hope process, and Prilleltensky and Prilleltensky’s (2007) Framework of psychosocial wellbeing which provides a broader context in which to view this process. Over a period of a year I engaged with twelve purposively selected 9-13 year old Basotho children, beneficiaries of a children’s programme situated in a rural village in the QwaQwa region, Free State, South Africa, to explore their hope. Using visual participatory methodology, data was co-constructed through four visual data generating tools (collage-making, drawing, Mmogo-method®, and photovoice), as well as individual interviews, a group interview, and notes and photographs kept in my research journal. A qualitative thematic analysis was followed, and a literature control conducted to re-contextualise the findings. The results of this study are presented in themes. The first three themes, Hope is having a better life; Hope is community participation and togetherness; and Hope is weakened by others and by one’s environment, combine to represent hope as a multi-layered, multi-dimensional experience towards attaining a better life on a contextual, personal, relational, and collective level. These levels of hope are all inter-related, interdependent, and influenced by cultural factors and the children’s belief system (or worldview). I therefore conclude that, according to these rural South African school children, hope is an internal process of being that develops within the individual, with assistance from external resources, and then extends outwardly through hopeful beliefs, feelings, and behaviours to promote togetherness, care, and respect in one’s community. The last three themes, Strengthened personal hope; Enhanced relational hope; and Mobilised collective hope, show that using visual participatory methodology to engage the participants in an exploration of hope potentially strengthened, enhanced, and mobilised their hope across three inter-related and overlapping levels: Personal, Relational, and Collective. The participants expressed a growing understanding of their hoping process, increased sense of autonomy, and improved coping skills for strengthening their own hope. They also began to refer to themselves as Hope Champions - able to foster hope in others by behaving in a hopeful manner, teaching others about hope, and offering care and support. I therefore conclude that this shifting view of themselves as competent and valuable members of the community mobilised their collective level of hope as they began to formulate ideas of how they could be active citizens in their community, pursuing collective wellbeing for themselves and other members of the community so that everyone could live a better life. The findings have several implications for educational psychologists working with marginalised and vulnerable children’s hope, for fostering hope in school contexts, and for educational hope research with marginalised children in rural South African communities. While this study cannot presume to have achieved long-term social change, it does certainly lay the foundation for proposing that ‘research as intervention’ has promising potential as ‘research as hope-intervention’ in educational contexts. In responding to the research question, I argue that visual participatory research methodology, when focused on hope, is in and of itself a hope-enhancing intervention. Consequently, combining visual participatory methodology with hope-focused explorations enables ‘research as hope-intervention’, facilitating a strengthening of the participants’ hope, and resulting in meaningful personal transformation. I conclude that using ‘research as hope-intervention’ with rural South African children holds many possibilities for mobilising a ‘pedagogy of hope’.
- Full Text:
- Date Issued: 2016
Research as hope intervention: a visual participatory study with rural South African school children
- Authors: Cherrington, Avivit Miriam
- Date: 2016
- Subjects: Affective education -- South Africa , Critical pedagogy -- South Africa , Hope -- Social aspects -- South Africa
- Language: English
- Type: Thesis , Doctoral , PhD (Education)
- Identifier: http://hdl.handle.net/10948/8350 , vital:26348
- Description: There is a dearth of knowledge on rural South African children’s perspectives of hope, and how their hope can be nurtured, shaped, and strengthened. Guided by a qualitative approach, and located within a critical transformative paradigm, this study explores the following research question: How could visual participatory methodology as ‘research as intervention’ enable rural South African primary school children to explore their conceptualisations of hope, as well as strengthen their hope? To answer this question I pose two sub-questions: Firstly, what are rural primary school children’s conceptualisations of hope? Secondly, how could using visual participatory methodology to explore their hope also strengthen the children’s hope? Hope plays a key role in the lives of people, influencing decisions and behaviour, as well as coping skills and wellbeing. The socio-economic and cultural contexts in which rural South African children find themselves are critical in enabling hope and influencing their psychosocial wellbeing. While international hope research boasts a diversity of theories, there is scarce representation of such research from an African perspective. Unable to turn to an Afrocentric theory of hope this study is framed by two theories from the global-North: Scioli’s (2007) Integrative theory of hope which provides a description of the individual’s hope process, and Prilleltensky and Prilleltensky’s (2007) Framework of psychosocial wellbeing which provides a broader context in which to view this process. Over a period of a year I engaged with twelve purposively selected 9-13 year old Basotho children, beneficiaries of a children’s programme situated in a rural village in the QwaQwa region, Free State, South Africa, to explore their hope. Using visual participatory methodology, data was co-constructed through four visual data generating tools (collage-making, drawing, Mmogo-method®, and photovoice), as well as individual interviews, a group interview, and notes and photographs kept in my research journal. A qualitative thematic analysis was followed, and a literature control conducted to re-contextualise the findings. The results of this study are presented in themes. The first three themes, Hope is having a better life; Hope is community participation and togetherness; and Hope is weakened by others and by one’s environment, combine to represent hope as a multi-layered, multi-dimensional experience towards attaining a better life on a contextual, personal, relational, and collective level. These levels of hope are all inter-related, interdependent, and influenced by cultural factors and the children’s belief system (or worldview). I therefore conclude that, according to these rural South African school children, hope is an internal process of being that develops within the individual, with assistance from external resources, and then extends outwardly through hopeful beliefs, feelings, and behaviours to promote togetherness, care, and respect in one’s community. The last three themes, Strengthened personal hope; Enhanced relational hope; and Mobilised collective hope, show that using visual participatory methodology to engage the participants in an exploration of hope potentially strengthened, enhanced, and mobilised their hope across three inter-related and overlapping levels: Personal, Relational, and Collective. The participants expressed a growing understanding of their hoping process, increased sense of autonomy, and improved coping skills for strengthening their own hope. They also began to refer to themselves as Hope Champions - able to foster hope in others by behaving in a hopeful manner, teaching others about hope, and offering care and support. I therefore conclude that this shifting view of themselves as competent and valuable members of the community mobilised their collective level of hope as they began to formulate ideas of how they could be active citizens in their community, pursuing collective wellbeing for themselves and other members of the community so that everyone could live a better life. The findings have several implications for educational psychologists working with marginalised and vulnerable children’s hope, for fostering hope in school contexts, and for educational hope research with marginalised children in rural South African communities. While this study cannot presume to have achieved long-term social change, it does certainly lay the foundation for proposing that ‘research as intervention’ has promising potential as ‘research as hope-intervention’ in educational contexts. In responding to the research question, I argue that visual participatory research methodology, when focused on hope, is in and of itself a hope-enhancing intervention. Consequently, combining visual participatory methodology with hope-focused explorations enables ‘research as hope-intervention’, facilitating a strengthening of the participants’ hope, and resulting in meaningful personal transformation. I conclude that using ‘research as hope-intervention’ with rural South African children holds many possibilities for mobilising a ‘pedagogy of hope’.
- Full Text:
- Date Issued: 2016
Resilience and attachment as mediators impacting upon the psychosocial sequelae of unwanted early sexual experiences
- Defferary,Tanya Elizabeth Michele
- Authors: Defferary,Tanya Elizabeth Michele
- Date: 2016
- Subjects: Resilience (Personality trait) Child sexual abuse , Attachment behaviour , Psychotherapy
- Language: English
- Type: Thesis , Doctoral , DPhil
- Identifier: http://hdl.handle.net/10948/12494 , vital:27074
- Description: Unwanted early sexual experiences (UESE) are traumatic experiences that many children worldwide are exposed to on a daily basis. Some of these victims struggle to adapt to life, whereas others become survivors, exhibiting post-traumatic growth after such an experience. South Africa has some of the highest UESE prevalence rates in the world, highlighting the importance of research conducted within this field in the country. With an overarching psychofortogenic framework, and through the implementation of a convergent parallel mixed methods research design, the study explored and described whether resilience and attachment act as mediators impacting upon the psychosocial sequelae which a UESE survivor might experience. The study was divided into three phases. Phase 1 consisted of a small-scale survey design which was conducted with 304 participants while Phase 2 consisted of nine semi-structure interviews with UESE survivors, who were volunteers from the original sample. Finally, Phase 3 provided an integrated summary of the findings from the first two phases. During Phase 1 significant findings relating to the survivors of UESE, their levels of resilience and attachment relationships were outlined. Of the total sample, 32.43% males and 30.5% females indicated that they had been exposed to a UESE. Most of the perpetrators were known to the survivors with friends being identified as the most common perpetrators. Parental relationships characterised by trust, open communication and less alienation were found to impact upon the degree to which participants reported being bothered by the UESE. Furthermore, parental alienation at the time of the UESE had a significantly negative impact on the survivors’ adult relationship styles. During Phase 2 a number of themes emerged including the manner of disclosure, reasons for delayed disclosure, relationship to the confidant, confidant’s response to disclosure, effects of the response to disclosure, the impact of the UESE upon the survivor, impact of the UESE on relationships, coping/resilience, advice to professionals, the confidant, and the survivor. The final phase confirmed the research hypothesis that resilience and attachment act as mediating factors impacting upon a variety of psychosocial sequelae which a UESE survivor might experience. Serendipitously, disclosure was found to be a mediating factor, securing a significant role within the study. In conclusion a future intervention titled ‘Post-Traumatic Growth: A UESE model of Disclosure, Resilience and Attachment’, was outlined, based on the study’s findings.
- Full Text:
- Date Issued: 2016
- Authors: Defferary,Tanya Elizabeth Michele
- Date: 2016
- Subjects: Resilience (Personality trait) Child sexual abuse , Attachment behaviour , Psychotherapy
- Language: English
- Type: Thesis , Doctoral , DPhil
- Identifier: http://hdl.handle.net/10948/12494 , vital:27074
- Description: Unwanted early sexual experiences (UESE) are traumatic experiences that many children worldwide are exposed to on a daily basis. Some of these victims struggle to adapt to life, whereas others become survivors, exhibiting post-traumatic growth after such an experience. South Africa has some of the highest UESE prevalence rates in the world, highlighting the importance of research conducted within this field in the country. With an overarching psychofortogenic framework, and through the implementation of a convergent parallel mixed methods research design, the study explored and described whether resilience and attachment act as mediators impacting upon the psychosocial sequelae which a UESE survivor might experience. The study was divided into three phases. Phase 1 consisted of a small-scale survey design which was conducted with 304 participants while Phase 2 consisted of nine semi-structure interviews with UESE survivors, who were volunteers from the original sample. Finally, Phase 3 provided an integrated summary of the findings from the first two phases. During Phase 1 significant findings relating to the survivors of UESE, their levels of resilience and attachment relationships were outlined. Of the total sample, 32.43% males and 30.5% females indicated that they had been exposed to a UESE. Most of the perpetrators were known to the survivors with friends being identified as the most common perpetrators. Parental relationships characterised by trust, open communication and less alienation were found to impact upon the degree to which participants reported being bothered by the UESE. Furthermore, parental alienation at the time of the UESE had a significantly negative impact on the survivors’ adult relationship styles. During Phase 2 a number of themes emerged including the manner of disclosure, reasons for delayed disclosure, relationship to the confidant, confidant’s response to disclosure, effects of the response to disclosure, the impact of the UESE upon the survivor, impact of the UESE on relationships, coping/resilience, advice to professionals, the confidant, and the survivor. The final phase confirmed the research hypothesis that resilience and attachment act as mediating factors impacting upon a variety of psychosocial sequelae which a UESE survivor might experience. Serendipitously, disclosure was found to be a mediating factor, securing a significant role within the study. In conclusion a future intervention titled ‘Post-Traumatic Growth: A UESE model of Disclosure, Resilience and Attachment’, was outlined, based on the study’s findings.
- Full Text:
- Date Issued: 2016
Rhenium complexes with multidentate imine-, amine-, thione-, thiol-, hydroxy- and carboxamide chelates
- Authors: Habarurema, Gratien
- Date: 2016
- Subjects: Rhenium Metal complexes
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10948/12679 , vital:27106
- Description: This study entails the synthesis, spectroscopic and structural characterization of new rhenium complexes with multidentate imine-, amine-, thione-, thiol-, hydroxy- and carboxamide chelates in various oxidation states. Rhenium(I) and (V) complexes with imidazolidine, pyrimidine and bridging pyridyl derivatives are reported in Chapter 3. The reactions of the potential tridentate N,N,Odonor ligand 2,2'-dipyridylketone (dpk) with trans-[ReOCl3(PPh3)2], (n-Bu4N)[ReOCl4] and trans-[ReOI2(OEt)(PPh3)2] led to the isolation of cis-[ReOCl2(edpm)], cis-[ReOCl2(dpk.OH)] and [ReO3(dpk.OH)] respectively (see Scheme 1). The reaction of (E)-N-((pyridine-2-yl)methylene)benzo[d]thiazol-2-amine (pbt) with trans- [ReOCl3(PPh3)2] produced a mononuclear oxorhenium(V) complex cis- [ReOCl2(epm)(PPh3)]. Both dpk and pbt exhibited a nucleophilic attack by acetonitrile (for Hedpm), water (for dpk) and ethanol (for pbt) leading to chelates that act as uninegative tridentate N,N,O- and bidentate N,O-donor chelates respectively. The reaction of [Re(CO)5Cl] with 2,3-dihydro-2,2-di(pyridin-2-yl)-1H-benzo[d]imidazole (H2dpb), (2,6-diaza-cyclohex-1-enylolonium)2-aza-benzoate (H2den) and 2-(2-(pyridine-2-yl)imidazolidin-2-yl)pyridine (H2pip) (see Scheme 1) gave rise to novel rhenium(I) complexes fac-[Re(CO)3(H2dmb)Cl], fac-[Re(CO)3(Hhdm)] and fac-[Re(CO)3(H2pip)]Cl respectively. The monomeric cationic salt fac-[Re(CO)3(H2salbam)]Br and ligand-bridged dimer fac- (μ-H2salet)[Re(CO)3]2 complexes were formed by the reactions of [Re(CO)5X] (X = Br or Cl) with the potentially heptadentate Schiff base 2,2,2-tris (salicylideneimino)- triethylamine (H3salet; Scheme 2) respectively. The reactions of the potentially hexadentate ligands acting as tridentate monoanionic N,N,O- or N,O,O-donor chelates N1-(3-(2-hydroxy enzylideneamino) propylamino) ethyl)benzylidenepropane-1,3-diamine (H2salpd) and N,N -bis(salicylidene) -3,6-dioxa-1,8-diaminooctane (H2saldane) (Scheme 2) with [Re(CO)5Cl] led to the isolation of the mononuclear and dinuclear complexes fac-[Re(CO)3(Hsaldane)] and fac-(μ-salpd)[Re(CO)3]2 respectively. The reactions of [Re(CO)5Cl] with the tetradentate ligands 2-{[2-hydroxy-3-{[(E)-(2- hydroxyphenyl)-methylidene]amino}propyl)imino]methyl}phenol (H2hmp), 6-((6E)- ((3E)-3-((oxocyclohexa-2,4-dienyl)methyleneamino)-2-hydroxypropylimino)methyl)- cyclohexa-2,4-dienone (H2hcd.H2O) zwitterion and 2-((1E)-1-((E)-3-(2-hydoxyphenylmethylideneamino)propylimino)methyl)phenol (H2hdp) (see Scheme 2) resulted in the formation of the neutral fac-[Re(CO)3(Hamp)], fac-[Re(CO)3(Hhetp)] and fac- [Re(CO)3(Happ)] respectively. The treatment of 2-((3-(2-hydroxybenzylamino)-propylamino)methyl)phenol (H2hbp) with [Re(CO)3Cl] and trans-[ReOCl3(PPh3)2] gave the fac-[Re(CO)3(Hhbp)] and (μ-O)[ReO(hbp)]2 complexes. The reactions of the ligands H2hmp, H2hdp and H2hap (see Scheme 2) with trans-[ReOBr3(PPh3)2] and trans-[ReOI2(OEt)(PPh3)2] produced dinuclear oxo-bridged rhenium(V) complexes (μ-O)[ReO(hmp)]2, [(μ-O)[ReO(hdp)]2 and (μ-O)[ReO(hap)]2 respectively. The neutral and anionic binding modes of thiosemicarbazones to the fac-[Re(CO)3]+, cis- [ReO2]+ and trans-[ReO2]+ cores have been investigated in Chapter 6. The reactions of the potentially tridentate ligand 1-{1-(2- hydroxyphenyl)ethylidene}-4- phenylthiosemicarbazide (H2hpt) (see Scheme 3) with [Re(CO)5Cl], cis-[ReO2I(PPh3)2]cand trans-[ReO2(py)4]Cl led to the isolation of the complexes fac-[Re(CO)3(H2hpt)2]Cl, [Re(hipt)(Hipht)(PPh3)] and trans-[ReO(hpt)(Hhpt)] respectively. The X-ray crystal analysis of the complexes show that the ligand H2hpt exhibits decomposition, thiol-enol tautomerism and a thiolate-iminium zwitterionic process, and coordinates in the neutral form via its thione sulfur and nitrogen and anionic through the azo nitrogen, thiolate sulfur and acetophenolic oxygen. A series of nitrogen-heterocyclic amide-, acid-, thiol- and diol-based ligands as well as their related monomeric rhenium(III) and (V) complexes have also been studied (see Chapter 7). The reaction of N-(2-(pyrazine-2-carboxamido)phenyl)pyrazine-2- carboxamide (H2ppc) (Scheme 3) with trans-[ReOBr3(PPh3)2] yielded the complex trans- [ReBr2(Hppca)(PPh3)2]. The reactions of trans-[ReOX3(PPh3)2] (X = Cl, Br) with pyridine-2,6-dicarboxylic acid (H2pda) produced the neutral oxorhenium(V) complexes [ReOX2(epca)(PPh3)]. The treatment of trans-[ReOBr3(PPh3)2] with 2-mercaptopyridine- 3-carboxylic acid (H2mpc) gave rise to the rhenium(III) complex [Re(empc)3(PPh3)]. The reaction of 2,6-bis(hydroxymethyl)pyridine (H2bhp) with trans-[ReOI2(EOt)(PPh3)2], trans-[ReOBr3(PPh3)2] and [Re(CO)5Cl] gave the complexes [ReO(Hbhp)2(PPh3)]I.PPh3, cis-[ReOBr2(Hbhp)(PPh3)] and fac-(μ- O)2[Re(CO)3(Hbhp)]2 respectively. Their X-ray crystal structures indicate that the ligand acts as a bidentate monoanionic N,O-donor chelate leaving a free aliphatic hydroxyl group.
- Full Text:
- Date Issued: 2016
- Authors: Habarurema, Gratien
- Date: 2016
- Subjects: Rhenium Metal complexes
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10948/12679 , vital:27106
- Description: This study entails the synthesis, spectroscopic and structural characterization of new rhenium complexes with multidentate imine-, amine-, thione-, thiol-, hydroxy- and carboxamide chelates in various oxidation states. Rhenium(I) and (V) complexes with imidazolidine, pyrimidine and bridging pyridyl derivatives are reported in Chapter 3. The reactions of the potential tridentate N,N,Odonor ligand 2,2'-dipyridylketone (dpk) with trans-[ReOCl3(PPh3)2], (n-Bu4N)[ReOCl4] and trans-[ReOI2(OEt)(PPh3)2] led to the isolation of cis-[ReOCl2(edpm)], cis-[ReOCl2(dpk.OH)] and [ReO3(dpk.OH)] respectively (see Scheme 1). The reaction of (E)-N-((pyridine-2-yl)methylene)benzo[d]thiazol-2-amine (pbt) with trans- [ReOCl3(PPh3)2] produced a mononuclear oxorhenium(V) complex cis- [ReOCl2(epm)(PPh3)]. Both dpk and pbt exhibited a nucleophilic attack by acetonitrile (for Hedpm), water (for dpk) and ethanol (for pbt) leading to chelates that act as uninegative tridentate N,N,O- and bidentate N,O-donor chelates respectively. The reaction of [Re(CO)5Cl] with 2,3-dihydro-2,2-di(pyridin-2-yl)-1H-benzo[d]imidazole (H2dpb), (2,6-diaza-cyclohex-1-enylolonium)2-aza-benzoate (H2den) and 2-(2-(pyridine-2-yl)imidazolidin-2-yl)pyridine (H2pip) (see Scheme 1) gave rise to novel rhenium(I) complexes fac-[Re(CO)3(H2dmb)Cl], fac-[Re(CO)3(Hhdm)] and fac-[Re(CO)3(H2pip)]Cl respectively. The monomeric cationic salt fac-[Re(CO)3(H2salbam)]Br and ligand-bridged dimer fac- (μ-H2salet)[Re(CO)3]2 complexes were formed by the reactions of [Re(CO)5X] (X = Br or Cl) with the potentially heptadentate Schiff base 2,2,2-tris (salicylideneimino)- triethylamine (H3salet; Scheme 2) respectively. The reactions of the potentially hexadentate ligands acting as tridentate monoanionic N,N,O- or N,O,O-donor chelates N1-(3-(2-hydroxy enzylideneamino) propylamino) ethyl)benzylidenepropane-1,3-diamine (H2salpd) and N,N -bis(salicylidene) -3,6-dioxa-1,8-diaminooctane (H2saldane) (Scheme 2) with [Re(CO)5Cl] led to the isolation of the mononuclear and dinuclear complexes fac-[Re(CO)3(Hsaldane)] and fac-(μ-salpd)[Re(CO)3]2 respectively. The reactions of [Re(CO)5Cl] with the tetradentate ligands 2-{[2-hydroxy-3-{[(E)-(2- hydroxyphenyl)-methylidene]amino}propyl)imino]methyl}phenol (H2hmp), 6-((6E)- ((3E)-3-((oxocyclohexa-2,4-dienyl)methyleneamino)-2-hydroxypropylimino)methyl)- cyclohexa-2,4-dienone (H2hcd.H2O) zwitterion and 2-((1E)-1-((E)-3-(2-hydoxyphenylmethylideneamino)propylimino)methyl)phenol (H2hdp) (see Scheme 2) resulted in the formation of the neutral fac-[Re(CO)3(Hamp)], fac-[Re(CO)3(Hhetp)] and fac- [Re(CO)3(Happ)] respectively. The treatment of 2-((3-(2-hydroxybenzylamino)-propylamino)methyl)phenol (H2hbp) with [Re(CO)3Cl] and trans-[ReOCl3(PPh3)2] gave the fac-[Re(CO)3(Hhbp)] and (μ-O)[ReO(hbp)]2 complexes. The reactions of the ligands H2hmp, H2hdp and H2hap (see Scheme 2) with trans-[ReOBr3(PPh3)2] and trans-[ReOI2(OEt)(PPh3)2] produced dinuclear oxo-bridged rhenium(V) complexes (μ-O)[ReO(hmp)]2, [(μ-O)[ReO(hdp)]2 and (μ-O)[ReO(hap)]2 respectively. The neutral and anionic binding modes of thiosemicarbazones to the fac-[Re(CO)3]+, cis- [ReO2]+ and trans-[ReO2]+ cores have been investigated in Chapter 6. The reactions of the potentially tridentate ligand 1-{1-(2- hydroxyphenyl)ethylidene}-4- phenylthiosemicarbazide (H2hpt) (see Scheme 3) with [Re(CO)5Cl], cis-[ReO2I(PPh3)2]cand trans-[ReO2(py)4]Cl led to the isolation of the complexes fac-[Re(CO)3(H2hpt)2]Cl, [Re(hipt)(Hipht)(PPh3)] and trans-[ReO(hpt)(Hhpt)] respectively. The X-ray crystal analysis of the complexes show that the ligand H2hpt exhibits decomposition, thiol-enol tautomerism and a thiolate-iminium zwitterionic process, and coordinates in the neutral form via its thione sulfur and nitrogen and anionic through the azo nitrogen, thiolate sulfur and acetophenolic oxygen. A series of nitrogen-heterocyclic amide-, acid-, thiol- and diol-based ligands as well as their related monomeric rhenium(III) and (V) complexes have also been studied (see Chapter 7). The reaction of N-(2-(pyrazine-2-carboxamido)phenyl)pyrazine-2- carboxamide (H2ppc) (Scheme 3) with trans-[ReOBr3(PPh3)2] yielded the complex trans- [ReBr2(Hppca)(PPh3)2]. The reactions of trans-[ReOX3(PPh3)2] (X = Cl, Br) with pyridine-2,6-dicarboxylic acid (H2pda) produced the neutral oxorhenium(V) complexes [ReOX2(epca)(PPh3)]. The treatment of trans-[ReOBr3(PPh3)2] with 2-mercaptopyridine- 3-carboxylic acid (H2mpc) gave rise to the rhenium(III) complex [Re(empc)3(PPh3)]. The reaction of 2,6-bis(hydroxymethyl)pyridine (H2bhp) with trans-[ReOI2(EOt)(PPh3)2], trans-[ReOBr3(PPh3)2] and [Re(CO)5Cl] gave the complexes [ReO(Hbhp)2(PPh3)]I.PPh3, cis-[ReOBr2(Hbhp)(PPh3)] and fac-(μ- O)2[Re(CO)3(Hbhp)]2 respectively. Their X-ray crystal structures indicate that the ligand acts as a bidentate monoanionic N,O-donor chelate leaving a free aliphatic hydroxyl group.
- Full Text:
- Date Issued: 2016
Rhenium complexes with pontentially multidentate ligands containing the amino, imino, hydroxy and thiol groups
- Authors: Mukiza, Janvier
- Date: 2016
- Subjects: Rhenium Thiols Ligands
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10948/12308 , vital:27053
- Description: The chemistry of rhenium has received considerable interest due to its versatility in various catalytic applications, fixation and especially the potential use of 186Re and 188Re radionuclides in nuclear medicine. This study investigates the synthesis and characterisation of rhenium complexes with potentially multidentate ligands containing the amino, imino, hydroxyl and thiol groups. It reports new rhenium complexes in the +1, +3, +4 and +5 oxidation states, which display structural diversity, from monomers to ligand-bridged dimers as well as metal-metal multiply bonded dimers. The reaction of orotic acid (H2oa) and 2-mercapto-orotic acid (H2moa) with trans- [ReOX3(PPh3)2] (X = Cl, Br) were studied and led to the formation of ligand-bridged dimers with metal-metal multiple bonds i.e. (μ-Br)(μ-O)(μ-oa)[Re2 IVBr(OEt)2(PPh3)2], (μ-X)(μ-O)(μ-oa)[Re2 IVX2(OiPr)(PPh3)2] and (μ-Cl)(μ-O)(μ-moa)2[Re(PPh3)]2. The reaction of H2oa with [ReO2(py)4]Cl, [Re(dab)Br3(PPh3)2] (H2dab = 1,2- diaminobenzene) and [Re(CO)5Cl] were also studied and monomeric complexes [ReO(py)2(OEt)(oa)], [Re(dab)Br(oa)(PPh3)2] and (Ph4P)[Re(CO)3(H2O)(oa)] were isolated. The treatment of 5-amino-orotic acid (H2aoa) with [ReOBr3(PPh3)2] led to dimers with metal-metal triple bonds ReIV≡ReIV i.e. (μ-Br)(μ-O)(μ-oa)[Re2 IVBr(OEt)2(PPh3)2], (μ-Br)(μ-O)(μ-oa)[Re2 IVBr2(OiPr)(PPh3)2], as well as the monomer [ReV(apd)Br(aoa)(PPh3)2] (apd2− = 5-imidopyrimidine-2,4-dione). The chelating ligand 5-aminopyrimidine-2,4-dione (H2apd) was formed by oxorhenium(V)-catalysed decarboxylation of 5-amino-orotic acid (H2aoa) (see Scheme 1). The reaction of the Schiff base derivative of 5-amino-ortic acid, salicylimine-orotic acid (H2soa), with trans-[ReOI2(OEt)(PPh3)2] in ethanol was also investigated and led to the formation of the rhenium(III) complex salt [Re(coa)I(PPh3)2]I [Hcoa = 5-(2- hydroxybenzylideneamino)pyrimidine-2,4(1H,3H)-dione]. The chelating Hcoa is also formed from the oxorhenium(V)-catalysed decarboxylation of H2soa and coordinates to the rhenium(III) ion as a monoanionic tridentate N,O,O-donor chelate via the phenolate and ketonic oxygens, and the imino nitrogen atom. However, decarboxylation of H2soa was not observed in its reaction with [ReOCl3(PPh3)2], which led to the isolation of [ReOCl(soa)(PPh3)]. The reaction of the carboxamide derivative of 5-aminoorotic acid, 5-(5-aminopyrimidine-2,4(1H,3H)- dioxamido)-1,2,3,6-tetrahedro-2,6-dioxopyrimidine-4-carboxylic acid (H2ampa) with [Re(CO)5Cl] in ethanol led to the formation of a zwitterionic rhenium(I) complex [Re(CO)3(H2O)(amef)] [amef = {5-(5-ammoniumpyrimidine-2,4(1H,3H)-dioxamido)- 1,2,3,6-tetrahedro-2,6-dioxopyrimidine-4-ethylformate}]. The chelating ion amef was formed from the combined tricarbonylrhenium(I)-catalysed esterification and aminoprotonation of H2ampa (see Scheme 1) and coordinates to the fac-[Re(CO)3]+ core as a dianionic bidentate N,N-donor chelate via the amido nitrgens.
- Full Text:
- Date Issued: 2016
- Authors: Mukiza, Janvier
- Date: 2016
- Subjects: Rhenium Thiols Ligands
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10948/12308 , vital:27053
- Description: The chemistry of rhenium has received considerable interest due to its versatility in various catalytic applications, fixation and especially the potential use of 186Re and 188Re radionuclides in nuclear medicine. This study investigates the synthesis and characterisation of rhenium complexes with potentially multidentate ligands containing the amino, imino, hydroxyl and thiol groups. It reports new rhenium complexes in the +1, +3, +4 and +5 oxidation states, which display structural diversity, from monomers to ligand-bridged dimers as well as metal-metal multiply bonded dimers. The reaction of orotic acid (H2oa) and 2-mercapto-orotic acid (H2moa) with trans- [ReOX3(PPh3)2] (X = Cl, Br) were studied and led to the formation of ligand-bridged dimers with metal-metal multiple bonds i.e. (μ-Br)(μ-O)(μ-oa)[Re2 IVBr(OEt)2(PPh3)2], (μ-X)(μ-O)(μ-oa)[Re2 IVX2(OiPr)(PPh3)2] and (μ-Cl)(μ-O)(μ-moa)2[Re(PPh3)]2. The reaction of H2oa with [ReO2(py)4]Cl, [Re(dab)Br3(PPh3)2] (H2dab = 1,2- diaminobenzene) and [Re(CO)5Cl] were also studied and monomeric complexes [ReO(py)2(OEt)(oa)], [Re(dab)Br(oa)(PPh3)2] and (Ph4P)[Re(CO)3(H2O)(oa)] were isolated. The treatment of 5-amino-orotic acid (H2aoa) with [ReOBr3(PPh3)2] led to dimers with metal-metal triple bonds ReIV≡ReIV i.e. (μ-Br)(μ-O)(μ-oa)[Re2 IVBr(OEt)2(PPh3)2], (μ-Br)(μ-O)(μ-oa)[Re2 IVBr2(OiPr)(PPh3)2], as well as the monomer [ReV(apd)Br(aoa)(PPh3)2] (apd2− = 5-imidopyrimidine-2,4-dione). The chelating ligand 5-aminopyrimidine-2,4-dione (H2apd) was formed by oxorhenium(V)-catalysed decarboxylation of 5-amino-orotic acid (H2aoa) (see Scheme 1). The reaction of the Schiff base derivative of 5-amino-ortic acid, salicylimine-orotic acid (H2soa), with trans-[ReOI2(OEt)(PPh3)2] in ethanol was also investigated and led to the formation of the rhenium(III) complex salt [Re(coa)I(PPh3)2]I [Hcoa = 5-(2- hydroxybenzylideneamino)pyrimidine-2,4(1H,3H)-dione]. The chelating Hcoa is also formed from the oxorhenium(V)-catalysed decarboxylation of H2soa and coordinates to the rhenium(III) ion as a monoanionic tridentate N,O,O-donor chelate via the phenolate and ketonic oxygens, and the imino nitrogen atom. However, decarboxylation of H2soa was not observed in its reaction with [ReOCl3(PPh3)2], which led to the isolation of [ReOCl(soa)(PPh3)]. The reaction of the carboxamide derivative of 5-aminoorotic acid, 5-(5-aminopyrimidine-2,4(1H,3H)- dioxamido)-1,2,3,6-tetrahedro-2,6-dioxopyrimidine-4-carboxylic acid (H2ampa) with [Re(CO)5Cl] in ethanol led to the formation of a zwitterionic rhenium(I) complex [Re(CO)3(H2O)(amef)] [amef = {5-(5-ammoniumpyrimidine-2,4(1H,3H)-dioxamido)- 1,2,3,6-tetrahedro-2,6-dioxopyrimidine-4-ethylformate}]. The chelating ion amef was formed from the combined tricarbonylrhenium(I)-catalysed esterification and aminoprotonation of H2ampa (see Scheme 1) and coordinates to the fac-[Re(CO)3]+ core as a dianionic bidentate N,N-donor chelate via the amido nitrgens.
- Full Text:
- Date Issued: 2016
Risk and portfolio management in microfinace institutional governance in Kampala metropolitan region
- Authors: Kyagulanyi, Ronald
- Date: 2016
- Subjects: Microfinance -- Uganda -- Kampala , Risk management -- Uganda -- Kampala , Portfolio management -- Uganda -- Kampala
- Language: English
- Type: Thesis , Doctoral , DCom
- Identifier: http://hdl.handle.net/10948/8532 , vital:26401
- Description: This study was undertaken to examine the issues relating to risk and loan portfolio management in Microfinance institutions in Uganda. The first objective of this study was to establish the extent of governance in MFIs in Kampala, by looking at the overall management of these institutions, assessing how decision are made, and looking at how they are staffed. The second objective is to establish the variables that best explain management of Micro-Finance Institutions (MFIs). The third objective is to identify the risk management of loan portfolios and lastly to provide recommendations based on the findings. The researcher used explanatory and survey research designs. A minimum sample 114 participants from 50 MFIs was used in data collection and analysis. The researcher employed principle component analysis (PCA) basing on Eigen values to identify variables above mean-scores and the nodes on the scree plot (ordered eigenvalues) denotes the number of variables that best explain the dimensions and conclusion on each variables was drawn basing on mean values of descriptive statistical analysis. Furthermore the orthonormal loadings display of the variables is employed basing on the first principle component that identified the names of variables above the mean score and final variable is drown basing on descriptive statistical analysis using mean scores focusing on those above the mean. The analysis is based on three dimensions of assessments, namely; Governance, Human capital and Risk Management. In general 227 variables were observed from the 3 dimensions, however by employing the PCA the researcher was in position to come up with those that best explain the 3 dimensions and in summary 29 out of 131 variables were identified by the PCA that best describes governance, 17 out of 72 variables were extracted that best explain what is taking in place in human capital whilst 5 out of 24 variables were extracted in relation to risk management. Furthermore conclusions are drawn by employing descriptive statistical analysis basing on mean scores of the variables identified by the PCA. Therefore out of the 29 variables identified by PCA on governance dimension, 19 variables on average have mean scores above 3 signifying good performance in those areas. Therefore the strength of MFIs under governance is seen in the following areas; The MFIs surveyed have strong board that is professionally ethical and knowledgeable in the area of managing financial institutions. They are performing better in the area of decision making, they do make timely decisions, and the board keeps on monitoring management and making sure that strategies agreed upon are properly implemented. The board is well committed in filing tax returns which is a legal requirement to all taxpaying institutions. However 10 variables showed sign of weakness because they have mean scores on average below 3. Management of MFIs need to strengthen its self in the area of allowing individual initiative in decision making, recognition of management committees in place, this smoothen the operations of the institution and lastly the board need to mentor the management, most of the personnel managing these institutions lack skills in managing the entity. On the side of human capital management, 17 variables identified by PCA, basing on their mean scores, 13 have mean scores above 3 showing good performance of MFIs. In this case the strength of MFIs lies in having educated human resources in place; MFIs gave the ability to exploit the available opportunities more especially targeting low income earners that for long have been neglected. However mores is needed under human capital dimension more especially in those areas where on average their mean scores was below 3 such as training programs where the respondents revealed that the type of training obtained does not match with the job requirements therefore they do not benefit from these programs. There is still a lot of bureaucracy within the management that slows the operations of the MFIs. This is further explained by having directors commuting as loan officers. Failure to accept risk exposes the entire institution to a vague of collapse. The last dimension is risk management and in this way, 5 variables were identified by the PCA, and basing on their mean scores, 3 variables showed good progress and that is having performance management system in place, there are limited complaints from the clients about the MFIs services offered and lastly all employees are given access rights to organisation resources, the loan schemes are open to all employees and no discrimination in service delivery, however 2 variables were identified with mean scores below 3 showing weaknesses within the systems. Therefore MFIs have to improve technologies used in their operations; the use of file carbines, off line computers exposes the institution to high degree of risk. There is need to strengthen their distribution channels so that the financial services offered reach out to clients at ease. Specifically the research study identified various risks like systematic risk, operational risk, credit risk, counterparty risk and legal risk in that they do affect the gross loan portfolio in MFIs and policy measures have been recommended to mitigate such risks in financial institutions. These risks can be mitigated by; • Having Internal control systems of checks and balances • Hedging of transactions through advance booking and paying cash in advance. • Diversification of portfolio, through investing in as many assets possible • Continuous reminder of their obligations and making a fall up of clients and as well insuring the loans. • Investors are encouraged to form a network of partners in the business • Continuous engagement of a legal adviser to the institutions. The study contributed to better understanding of risk management in MFIs, that no single variable can be relied upon to explain effective management of risks but however in this study three dimensions play a crucial role in management of risks. The MFI management should focus on having an internal audit function operating independently in that financial controls should be regularly updated to cope with the changing environment. Audit committee of the board should be complete enough to supervise and regulate internal control systems, written policies in the organization should be effectively implemented with clear division of responsibilities of middle to top managers and lastly Segregation of powers and authority need to be strongly emphasized as a way of enhancing proper management of risks in MFIs.
- Full Text:
- Date Issued: 2016
Risk and portfolio management in microfinace institutional governance in Kampala metropolitan region
- Authors: Kyagulanyi, Ronald
- Date: 2016
- Subjects: Microfinance -- Uganda -- Kampala , Risk management -- Uganda -- Kampala , Portfolio management -- Uganda -- Kampala
- Language: English
- Type: Thesis , Doctoral , DCom
- Identifier: http://hdl.handle.net/10948/8532 , vital:26401
- Description: This study was undertaken to examine the issues relating to risk and loan portfolio management in Microfinance institutions in Uganda. The first objective of this study was to establish the extent of governance in MFIs in Kampala, by looking at the overall management of these institutions, assessing how decision are made, and looking at how they are staffed. The second objective is to establish the variables that best explain management of Micro-Finance Institutions (MFIs). The third objective is to identify the risk management of loan portfolios and lastly to provide recommendations based on the findings. The researcher used explanatory and survey research designs. A minimum sample 114 participants from 50 MFIs was used in data collection and analysis. The researcher employed principle component analysis (PCA) basing on Eigen values to identify variables above mean-scores and the nodes on the scree plot (ordered eigenvalues) denotes the number of variables that best explain the dimensions and conclusion on each variables was drawn basing on mean values of descriptive statistical analysis. Furthermore the orthonormal loadings display of the variables is employed basing on the first principle component that identified the names of variables above the mean score and final variable is drown basing on descriptive statistical analysis using mean scores focusing on those above the mean. The analysis is based on three dimensions of assessments, namely; Governance, Human capital and Risk Management. In general 227 variables were observed from the 3 dimensions, however by employing the PCA the researcher was in position to come up with those that best explain the 3 dimensions and in summary 29 out of 131 variables were identified by the PCA that best describes governance, 17 out of 72 variables were extracted that best explain what is taking in place in human capital whilst 5 out of 24 variables were extracted in relation to risk management. Furthermore conclusions are drawn by employing descriptive statistical analysis basing on mean scores of the variables identified by the PCA. Therefore out of the 29 variables identified by PCA on governance dimension, 19 variables on average have mean scores above 3 signifying good performance in those areas. Therefore the strength of MFIs under governance is seen in the following areas; The MFIs surveyed have strong board that is professionally ethical and knowledgeable in the area of managing financial institutions. They are performing better in the area of decision making, they do make timely decisions, and the board keeps on monitoring management and making sure that strategies agreed upon are properly implemented. The board is well committed in filing tax returns which is a legal requirement to all taxpaying institutions. However 10 variables showed sign of weakness because they have mean scores on average below 3. Management of MFIs need to strengthen its self in the area of allowing individual initiative in decision making, recognition of management committees in place, this smoothen the operations of the institution and lastly the board need to mentor the management, most of the personnel managing these institutions lack skills in managing the entity. On the side of human capital management, 17 variables identified by PCA, basing on their mean scores, 13 have mean scores above 3 showing good performance of MFIs. In this case the strength of MFIs lies in having educated human resources in place; MFIs gave the ability to exploit the available opportunities more especially targeting low income earners that for long have been neglected. However mores is needed under human capital dimension more especially in those areas where on average their mean scores was below 3 such as training programs where the respondents revealed that the type of training obtained does not match with the job requirements therefore they do not benefit from these programs. There is still a lot of bureaucracy within the management that slows the operations of the MFIs. This is further explained by having directors commuting as loan officers. Failure to accept risk exposes the entire institution to a vague of collapse. The last dimension is risk management and in this way, 5 variables were identified by the PCA, and basing on their mean scores, 3 variables showed good progress and that is having performance management system in place, there are limited complaints from the clients about the MFIs services offered and lastly all employees are given access rights to organisation resources, the loan schemes are open to all employees and no discrimination in service delivery, however 2 variables were identified with mean scores below 3 showing weaknesses within the systems. Therefore MFIs have to improve technologies used in their operations; the use of file carbines, off line computers exposes the institution to high degree of risk. There is need to strengthen their distribution channels so that the financial services offered reach out to clients at ease. Specifically the research study identified various risks like systematic risk, operational risk, credit risk, counterparty risk and legal risk in that they do affect the gross loan portfolio in MFIs and policy measures have been recommended to mitigate such risks in financial institutions. These risks can be mitigated by; • Having Internal control systems of checks and balances • Hedging of transactions through advance booking and paying cash in advance. • Diversification of portfolio, through investing in as many assets possible • Continuous reminder of their obligations and making a fall up of clients and as well insuring the loans. • Investors are encouraged to form a network of partners in the business • Continuous engagement of a legal adviser to the institutions. The study contributed to better understanding of risk management in MFIs, that no single variable can be relied upon to explain effective management of risks but however in this study three dimensions play a crucial role in management of risks. The MFI management should focus on having an internal audit function operating independently in that financial controls should be regularly updated to cope with the changing environment. Audit committee of the board should be complete enough to supervise and regulate internal control systems, written policies in the organization should be effectively implemented with clear division of responsibilities of middle to top managers and lastly Segregation of powers and authority need to be strongly emphasized as a way of enhancing proper management of risks in MFIs.
- Full Text:
- Date Issued: 2016
Rural livelihood strategies of female headed households in former Bantustans of post-apartheid South Africa: The case of Cala, Eastern Cape Province.
- Authors: Chirau, Takunda John
- Date: 2016
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:3410 , http://hdl.handle.net/10962/d1021301
- Description: Communal areas in contemporary South Africa (that is, the former Bantustans of apartheid South Africa) continue to bear and endure, albeit in new forms, socio-economic and political vulnerabilities which are negatively affecting household livelihoods. Current studies on rural livelihoods have failed to keep pace in exploring and analysing the lived experiences and ever-changing challenges faced by these rural households. This thesis provides an understanding and explanation of the livelihood activities of specifically de facto and de jure female-headed households in the former Transkei Bantustan, with a specific focus on villages in Cala. This is framed analytically by feminist theories with their emphasis on systems of patriarchy and by a rural livelihoods framework. It uses a multiplicity of research methods, including focus group discussions, in-depth interviews, life histories and survey questionnaires. The major findings of the thesis show that the female-headed households in Cala depend upon agricultural-based activities and non-agriculturally-based activities and income (including social grants) but that they exist under conditions of extreme vulnerability which are subject to fluctuation. In the end, the livelihoods of female-headed households are precarious and unstable as they live under circumstances of poverty. However, the female heads are not mere passive victims of the rural crisis in post-apartheid South Africa, as they demonstrate qualities of ingenuity and resourcefulness including through a range of coping mechanisms. At the same time, rural communities continue to be marked by patriarchal norms and practices, including systems of chieftainship, which disempower women (including female heads), though this affects de jure heads and de facto heads differently. The thesis contributes to an understanding of rural livelihoods in communal areas (or former Bantustans) of present-day South Africa by way of ‘thick descriptions’ of the everyday lives of female heads in Cala. Further, in examining rural livelihoods, it highlights the importance of bringing to bear on the livelihoods framework a feminist perspective in pinpointing the additional livelihood burdens carried by rural women.
- Full Text:
- Date Issued: 2016
- Authors: Chirau, Takunda John
- Date: 2016
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:3410 , http://hdl.handle.net/10962/d1021301
- Description: Communal areas in contemporary South Africa (that is, the former Bantustans of apartheid South Africa) continue to bear and endure, albeit in new forms, socio-economic and political vulnerabilities which are negatively affecting household livelihoods. Current studies on rural livelihoods have failed to keep pace in exploring and analysing the lived experiences and ever-changing challenges faced by these rural households. This thesis provides an understanding and explanation of the livelihood activities of specifically de facto and de jure female-headed households in the former Transkei Bantustan, with a specific focus on villages in Cala. This is framed analytically by feminist theories with their emphasis on systems of patriarchy and by a rural livelihoods framework. It uses a multiplicity of research methods, including focus group discussions, in-depth interviews, life histories and survey questionnaires. The major findings of the thesis show that the female-headed households in Cala depend upon agricultural-based activities and non-agriculturally-based activities and income (including social grants) but that they exist under conditions of extreme vulnerability which are subject to fluctuation. In the end, the livelihoods of female-headed households are precarious and unstable as they live under circumstances of poverty. However, the female heads are not mere passive victims of the rural crisis in post-apartheid South Africa, as they demonstrate qualities of ingenuity and resourcefulness including through a range of coping mechanisms. At the same time, rural communities continue to be marked by patriarchal norms and practices, including systems of chieftainship, which disempower women (including female heads), though this affects de jure heads and de facto heads differently. The thesis contributes to an understanding of rural livelihoods in communal areas (or former Bantustans) of present-day South Africa by way of ‘thick descriptions’ of the everyday lives of female heads in Cala. Further, in examining rural livelihoods, it highlights the importance of bringing to bear on the livelihoods framework a feminist perspective in pinpointing the additional livelihood burdens carried by rural women.
- Full Text:
- Date Issued: 2016
Scalable chemistry involving diazonium salts
- Authors: Akwi, Faith Mary
- Date: 2016
- Subjects: Azo compounds -- Synthesis , Chemical processes
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10948/6909 , vital:21162
- Description: Herein an alternative approach aimed at reducing the cost of numbering up technique as a scale up strategy for chemical processes from the laboratory bench top to the industry is explored. The effect of increasing channel size on the reaction conversion of the synthesis of azo compounds is investigated. This was achieved via a systematic investigative understanding of the synthesis in microreactors where a proof of concept study was performed to determine the optimum reaction parameters in azo coupling reactions involving couplers with aminated or hydroxylated groups in Little Things Factory-MS microreactors (Channel diameter: 1.0 mm) It was found that at slightly alkaline conditions (pH 8.55) and at a temperature of 25 °C, excellent conversions were attained in the azo coupling reaction of the diazonium salt solution of 2,4-dimethylaniline to 2-naphthol. On the other hand, the azo coupling reaction of the diazonium salt solution of p-nitroaniline to diphenylamine was found to thrive at a pH of 5.71 and at a temperature of 25 °C. Using, these optimized reaction parameters, the in-situ and reactive quench of diazonium salts in LTF-MS microreactors was investigated where it was found that at a flow rate of 0.2 ml/min, 0.03 ml/min and 0.07 ml/min of diazotizable amine & HCl, sodium nitrite and coupler solutions respectively, a conversion of 98% is achieved in approximately 2.4 minutes. A library of azo compounds was thus generated under these reaction conditions from couplers with aminated or hydroxylated aromatic aromatic systems. The scaled up synthesis of these compounds in a homemade PTFE tubing (ID 1.5 mm) reactor system was thereafter investigated and comparable conversions were observed. Capitalizing on the benefits of a large surface area and the short molecular diffusion distances observed in microreactors, in-situ phase transfer catalyzed azo coupling reaction of diphenylamine to p-nitroaniline was also explored. In this investigation a rapid and easy optimization protocol that yielded a 99%, 22% and 33% conversion of diphenylamine, carbazole and triphenylamine respectively in approximately 2.4 minutes using Chemtrix microreactors was established. On increasing the microreactor channel internal diameter in the scaled up synthesis approach, it was found that a 0.5 mm increase in channel internal diameter does result in lower reaction conversions.
- Full Text:
- Date Issued: 2016
- Authors: Akwi, Faith Mary
- Date: 2016
- Subjects: Azo compounds -- Synthesis , Chemical processes
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10948/6909 , vital:21162
- Description: Herein an alternative approach aimed at reducing the cost of numbering up technique as a scale up strategy for chemical processes from the laboratory bench top to the industry is explored. The effect of increasing channel size on the reaction conversion of the synthesis of azo compounds is investigated. This was achieved via a systematic investigative understanding of the synthesis in microreactors where a proof of concept study was performed to determine the optimum reaction parameters in azo coupling reactions involving couplers with aminated or hydroxylated groups in Little Things Factory-MS microreactors (Channel diameter: 1.0 mm) It was found that at slightly alkaline conditions (pH 8.55) and at a temperature of 25 °C, excellent conversions were attained in the azo coupling reaction of the diazonium salt solution of 2,4-dimethylaniline to 2-naphthol. On the other hand, the azo coupling reaction of the diazonium salt solution of p-nitroaniline to diphenylamine was found to thrive at a pH of 5.71 and at a temperature of 25 °C. Using, these optimized reaction parameters, the in-situ and reactive quench of diazonium salts in LTF-MS microreactors was investigated where it was found that at a flow rate of 0.2 ml/min, 0.03 ml/min and 0.07 ml/min of diazotizable amine & HCl, sodium nitrite and coupler solutions respectively, a conversion of 98% is achieved in approximately 2.4 minutes. A library of azo compounds was thus generated under these reaction conditions from couplers with aminated or hydroxylated aromatic aromatic systems. The scaled up synthesis of these compounds in a homemade PTFE tubing (ID 1.5 mm) reactor system was thereafter investigated and comparable conversions were observed. Capitalizing on the benefits of a large surface area and the short molecular diffusion distances observed in microreactors, in-situ phase transfer catalyzed azo coupling reaction of diphenylamine to p-nitroaniline was also explored. In this investigation a rapid and easy optimization protocol that yielded a 99%, 22% and 33% conversion of diphenylamine, carbazole and triphenylamine respectively in approximately 2.4 minutes using Chemtrix microreactors was established. On increasing the microreactor channel internal diameter in the scaled up synthesis approach, it was found that a 0.5 mm increase in channel internal diameter does result in lower reaction conversions.
- Full Text:
- Date Issued: 2016
Selecting and augmenting a FOSS development and deployment environment for personalized video-oriented services in a Telco context
- Authors: Shibeshi, Zelalem Sintayehu
- Date: 2016
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/943 , vital:20005
- Description: The great demand for video services on the Internet is one contributing factor that led telecom companies to search for solutions to deliver innovative video services, using the different access technologies managed by them and leveraging the capacity of enforcing Quality of Service (QoS). One part of the solution was an infrastructure that guarantees QoS for these services, in the form of the IP Multimedia Subsystem (IMS) framework. The IMS framework was developed for delivering innovative multimedia services, but IMS alone does not provide the required services. This has led to further work in the area of multimedia service architectures. One noteworthy architecture is IPTV. IPTV is more than what its name implies, as it allows the development of various innovative video-oriented services and not just tv. When IPTV was introduced, many thought that it would bring back the revenue loss that telecom companies experienced to over-the-top (OTT) service providers. However, despite all its promises, the IPTV implementation has not shown as wide an uptake as one would expect. Although there could be various reasons for the slow penetration of IPTV, one reason could be the technical challenge that IPTV poses to service developers. One of the main reasons for the embarking of the research reported in this thesis was to identify and select free and open source software (FOSS) based platforms and augment them for easy development and deployment of video-oriented services. The thesis motivated how the IPTV architecture, with some modification, can be a good architecture to develop innovative video-oriented services. For a better understanding and investigate the issues of video-oriented service development on different platforms, we followed an incremental and iterative prototyping method. As a result, various video-oriented services were first developed and implementation-related issues were analyzed. This has helped us to identify problems that service developers face, including the requirement to utilize a number of protocols to develop an IPTV-based video-oriented service and the lack of a platform that provides a consistent programming interface to implement them all. The process also helped us to identify new uses cases through the process. As part of our selection process, we found that the Mobicents service development platform can be used as the basis for a good service development and deployment environment for video-oriented services. Mobicents is a Java-based service delivery platform for quick development, deployment and management of next generation network applications. Mobicents is a good choice because it provides a consistent programming interface and supports the various protocols needed in a consistent manner or an easy way to include the support for them. We used Mobicents to compose the environment that developers can use to build video-oriented services. Specifically we developed components and service building blocks that service developer can use to develop various innovative video-oriented services. During our research, we also identified various issues with regard to support from streaming servers in general and open source streaming servers in particular and also with the protocol they use. Specifically, we identified issues with Real Time Streaming Protocol (RTSP), a protocol specified as the media control protocol in the IPTV specification, and made proposals for solving them. We developed an RSTP proxy to augment the features lacking in the current streaming servers and implemented some of the features we proposed in it.
- Full Text:
- Date Issued: 2016
- Authors: Shibeshi, Zelalem Sintayehu
- Date: 2016
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/943 , vital:20005
- Description: The great demand for video services on the Internet is one contributing factor that led telecom companies to search for solutions to deliver innovative video services, using the different access technologies managed by them and leveraging the capacity of enforcing Quality of Service (QoS). One part of the solution was an infrastructure that guarantees QoS for these services, in the form of the IP Multimedia Subsystem (IMS) framework. The IMS framework was developed for delivering innovative multimedia services, but IMS alone does not provide the required services. This has led to further work in the area of multimedia service architectures. One noteworthy architecture is IPTV. IPTV is more than what its name implies, as it allows the development of various innovative video-oriented services and not just tv. When IPTV was introduced, many thought that it would bring back the revenue loss that telecom companies experienced to over-the-top (OTT) service providers. However, despite all its promises, the IPTV implementation has not shown as wide an uptake as one would expect. Although there could be various reasons for the slow penetration of IPTV, one reason could be the technical challenge that IPTV poses to service developers. One of the main reasons for the embarking of the research reported in this thesis was to identify and select free and open source software (FOSS) based platforms and augment them for easy development and deployment of video-oriented services. The thesis motivated how the IPTV architecture, with some modification, can be a good architecture to develop innovative video-oriented services. For a better understanding and investigate the issues of video-oriented service development on different platforms, we followed an incremental and iterative prototyping method. As a result, various video-oriented services were first developed and implementation-related issues were analyzed. This has helped us to identify problems that service developers face, including the requirement to utilize a number of protocols to develop an IPTV-based video-oriented service and the lack of a platform that provides a consistent programming interface to implement them all. The process also helped us to identify new uses cases through the process. As part of our selection process, we found that the Mobicents service development platform can be used as the basis for a good service development and deployment environment for video-oriented services. Mobicents is a Java-based service delivery platform for quick development, deployment and management of next generation network applications. Mobicents is a good choice because it provides a consistent programming interface and supports the various protocols needed in a consistent manner or an easy way to include the support for them. We used Mobicents to compose the environment that developers can use to build video-oriented services. Specifically we developed components and service building blocks that service developer can use to develop various innovative video-oriented services. During our research, we also identified various issues with regard to support from streaming servers in general and open source streaming servers in particular and also with the protocol they use. Specifically, we identified issues with Real Time Streaming Protocol (RTSP), a protocol specified as the media control protocol in the IPTV specification, and made proposals for solving them. We developed an RSTP proxy to augment the features lacking in the current streaming servers and implemented some of the features we proposed in it.
- Full Text:
- Date Issued: 2016
Self-reflection practices of school-management teams in the Capricorn District : towards a reflective management strategy for South African schools
- Authors: Malatji, Khashane Stephen
- Date: 2016
- Subjects: School management teams -- South Africa Educational leadership -- South Africa School management and organization -- South Africa
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10353/3021 , vital:28238
- Description: The study investigated the self-reflection practices of School Management Teams (SMTs) in the Capricorn District. The purpose of the study was to establish self-reflective practices employed by SMT in performing their management functions, and to suggest a reflective model for the enhancement of SMT performance. The study followed the qualitative approach with a case-study research design. The population consisted of SMTs from primary, secondary and special schools. Purposive sampling was utilised to select 8 Head of Departments from less experienced to more experienced in management positions, while 9 principal and 9 deputy principals were randomly selected. Literature reviewed focused on the aims of self-reflection; the functions of SMT; the strengths and weaknesses of self-reflection; self-reflective practices and enhanced performance; models of school management; challenges in school management; and previous studies on SMT and school management. Henderson’s Ethical Model of Enquiry on reflective practice was used. The theory discusses what characterises reflective practitioners. Data was collected from quest views, individual interviews and focus group interviews. The interpretation and understanding were organised in the form of descriptive accounts. Tape-recorded interviews and data from quest views were transcribed verbatim. After transcribing data a sense of the whole was obtained by reading carefully with understanding, and then summarizing the salient aspects. Themes were identified from the responses and discussed. The study found that SMT members were not fully aware of all of their daily functions and poor reflective practices made it difficult for them to effectively fulfil their management functions. Furthermore, the study revealed that SMT members experienced challenges, such as dealing with unprofessional teachers, poor parental involvement, poor communication, poor infrastructure and lack of resources amd these impacted negatively on their performance. The study provided insights into the practice of self-reflection and how SMT members could become reflective practitioners. A new framework was suggested that SMTs should continuously and critically reflect on their management practices and decisions. The study recommends that SMT be trained and oriented about management functions prior to their appointment in the positions. The study further recommends that SMTs consider self-reflection as part of their daily activities.
- Full Text:
- Date Issued: 2016
- Authors: Malatji, Khashane Stephen
- Date: 2016
- Subjects: School management teams -- South Africa Educational leadership -- South Africa School management and organization -- South Africa
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10353/3021 , vital:28238
- Description: The study investigated the self-reflection practices of School Management Teams (SMTs) in the Capricorn District. The purpose of the study was to establish self-reflective practices employed by SMT in performing their management functions, and to suggest a reflective model for the enhancement of SMT performance. The study followed the qualitative approach with a case-study research design. The population consisted of SMTs from primary, secondary and special schools. Purposive sampling was utilised to select 8 Head of Departments from less experienced to more experienced in management positions, while 9 principal and 9 deputy principals were randomly selected. Literature reviewed focused on the aims of self-reflection; the functions of SMT; the strengths and weaknesses of self-reflection; self-reflective practices and enhanced performance; models of school management; challenges in school management; and previous studies on SMT and school management. Henderson’s Ethical Model of Enquiry on reflective practice was used. The theory discusses what characterises reflective practitioners. Data was collected from quest views, individual interviews and focus group interviews. The interpretation and understanding were organised in the form of descriptive accounts. Tape-recorded interviews and data from quest views were transcribed verbatim. After transcribing data a sense of the whole was obtained by reading carefully with understanding, and then summarizing the salient aspects. Themes were identified from the responses and discussed. The study found that SMT members were not fully aware of all of their daily functions and poor reflective practices made it difficult for them to effectively fulfil their management functions. Furthermore, the study revealed that SMT members experienced challenges, such as dealing with unprofessional teachers, poor parental involvement, poor communication, poor infrastructure and lack of resources amd these impacted negatively on their performance. The study provided insights into the practice of self-reflection and how SMT members could become reflective practitioners. A new framework was suggested that SMTs should continuously and critically reflect on their management practices and decisions. The study recommends that SMT be trained and oriented about management functions prior to their appointment in the positions. The study further recommends that SMTs consider self-reflection as part of their daily activities.
- Full Text:
- Date Issued: 2016
Shifting identities: An exploration of the possibilities for a syncretic Afrikaans theatre by means of three case studies – Hex (2003), Lady Anne (2007), Ekspedisies (2008)
- Authors: Gehring, Heike
- Date: 2016
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:2165 , http://hdl.handle.net/10962/d1021269
- Description: This thesis investigates the possibilities for syncretic Afrikaans language theatre within a post-1994 South African society. The research sets out to explore in what manner theatre can be language-specific, while at the same time being able to cross language contexts. This exploration is driven by the wish to develop strategies for creating Afrikaans theatre that is able to reflect on a society “united in diversity”. In this regard it is argued that for theatre to be able to both retain and cross language barriers, processes of bonding and bridging are necessary. The thesis sets out first to explain why these processes are required and then to suggest ways in which such processes can be implemented in practice. A triangular approach is used, in which conceptual and theoretical frameworks are developed to reflect on actual theatre practices. Three of my own productions are used as case studies, namely Hex (2000; 2003), Lady Anne (2007) and Ekspedisies (2008). These productions can be understood to be “boundary objects” in Henk Borgdorff’s (2012: 177) sense of the word, in that they fulfil a dual function: they are artistic productions that can also be reconstituted to serve a research purpose beyond the productions themselves. All three works were first created for public consumption before becoming cases for this thesis. Many of the strategies that were developed and tested in creating these productions are examples of ways in which bonding and bridging in Afrikaans language theatre can be understood. Chapter One of the thesis contextualises the political currents and events that necessitated the impulse towards “bonding and bridging”. In this case the political and ethical impetus behind the practical explorations has been related predominantly to the democratisation of South African society, in which a paradigm shift happened from viewing the Afrikaans language as one over many to one amongst many. Within a multilingual South Africa, concerns are raised about ways in which to create theatre in South African languages other than English (often understood to be the only possible bridging language) that are able to cross language divides. Following this introduction to language-related concerns, Chapter Two explains how the shift from apartheid to democracy made space for shifts in identity – on personal as well as institutional levels: a progression from essentialised notions of culture to the celebration of plurality. This progression is then related to theatre, with an explanation of how the post-1994 theatre landscape demanded a reimagining of the form and function of theatre. In this re-imagination the notion of a “third space” is important; something that is introduced in this chapter as an alternative to polarised identity constructions. The function of the “third space” as an in-between space and a meeting point for diverse people and entities is a strong underlying theme of this thesis and it serves as a reoccurring touchstone to the ideas put forward. Chapter Three discusses the South African arts festival culture and its contribution to the South African theatre landscape. Particular focus is placed on the Klein Karoo National Arts festival (KKNK) as a platform for the development of the Afrikaans language within a post-1994 context. What is emphasized in particular is the attempt by the KKNK festival to be linguistically and culturally exploratory and inclusive in the face of language protectionism. After the contextual background of the first three chapters, the thesis shifts to an analysis of theories related to “hybridity” and “syncretism”. In Chapter Four the argument is put forward that of the various inclusive performance and theatre models that represent a multicultural society, the most responsive forms are those that are syncretic and hybrid. Principles that can contribute to the unification and merging of diverse and polarized societal groups are described, and suggestions are made for possible ways to bring about bonding and bridging within cultural practices. Having introduced these principles, examples are offered of how these theories might be understood in other disciplines, namely, religious studies, anthropology, history and a range of cultural practices. Following this broad discussion, Chapter Five describes syncretism and hybridity more specifically in theatre by means of relevant examples. Taking the discussion further into the realm of application, Chapter Six offers an overview of “workshop theatre”, “translation” and “collage making” as strategies for putting theories of hybridity and syncretism into practice. This is followed (in Chapters Seven, Eight and Nine) by a discussion of the three productions (Hex, Lady Anne and Ekspedisies) as case studies that demonstrate how these theories can be understood in practice. Practical strategies for bridging language divides are foregrounded, such as code switching as an approach for enabling a “co-habitation” of languages; physical theatre as a means for crossing language divides; and the creation of more than one language version of a production as a tactic to accommodate shifting contexts. Following on from the discoveries made in the foregoing chapters, I conclude that theories and practices related to notions of “third space”, “hybridity” and “syncretism” are ideal for creating theatre forms (in the Afrikaans language in particular) that can truly reflect a South African society which is “united in diversity”. The thesis ends by offering suggestions for ways in which new, future identities, can be developed.
- Full Text:
- Date Issued: 2016
- Authors: Gehring, Heike
- Date: 2016
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:2165 , http://hdl.handle.net/10962/d1021269
- Description: This thesis investigates the possibilities for syncretic Afrikaans language theatre within a post-1994 South African society. The research sets out to explore in what manner theatre can be language-specific, while at the same time being able to cross language contexts. This exploration is driven by the wish to develop strategies for creating Afrikaans theatre that is able to reflect on a society “united in diversity”. In this regard it is argued that for theatre to be able to both retain and cross language barriers, processes of bonding and bridging are necessary. The thesis sets out first to explain why these processes are required and then to suggest ways in which such processes can be implemented in practice. A triangular approach is used, in which conceptual and theoretical frameworks are developed to reflect on actual theatre practices. Three of my own productions are used as case studies, namely Hex (2000; 2003), Lady Anne (2007) and Ekspedisies (2008). These productions can be understood to be “boundary objects” in Henk Borgdorff’s (2012: 177) sense of the word, in that they fulfil a dual function: they are artistic productions that can also be reconstituted to serve a research purpose beyond the productions themselves. All three works were first created for public consumption before becoming cases for this thesis. Many of the strategies that were developed and tested in creating these productions are examples of ways in which bonding and bridging in Afrikaans language theatre can be understood. Chapter One of the thesis contextualises the political currents and events that necessitated the impulse towards “bonding and bridging”. In this case the political and ethical impetus behind the practical explorations has been related predominantly to the democratisation of South African society, in which a paradigm shift happened from viewing the Afrikaans language as one over many to one amongst many. Within a multilingual South Africa, concerns are raised about ways in which to create theatre in South African languages other than English (often understood to be the only possible bridging language) that are able to cross language divides. Following this introduction to language-related concerns, Chapter Two explains how the shift from apartheid to democracy made space for shifts in identity – on personal as well as institutional levels: a progression from essentialised notions of culture to the celebration of plurality. This progression is then related to theatre, with an explanation of how the post-1994 theatre landscape demanded a reimagining of the form and function of theatre. In this re-imagination the notion of a “third space” is important; something that is introduced in this chapter as an alternative to polarised identity constructions. The function of the “third space” as an in-between space and a meeting point for diverse people and entities is a strong underlying theme of this thesis and it serves as a reoccurring touchstone to the ideas put forward. Chapter Three discusses the South African arts festival culture and its contribution to the South African theatre landscape. Particular focus is placed on the Klein Karoo National Arts festival (KKNK) as a platform for the development of the Afrikaans language within a post-1994 context. What is emphasized in particular is the attempt by the KKNK festival to be linguistically and culturally exploratory and inclusive in the face of language protectionism. After the contextual background of the first three chapters, the thesis shifts to an analysis of theories related to “hybridity” and “syncretism”. In Chapter Four the argument is put forward that of the various inclusive performance and theatre models that represent a multicultural society, the most responsive forms are those that are syncretic and hybrid. Principles that can contribute to the unification and merging of diverse and polarized societal groups are described, and suggestions are made for possible ways to bring about bonding and bridging within cultural practices. Having introduced these principles, examples are offered of how these theories might be understood in other disciplines, namely, religious studies, anthropology, history and a range of cultural practices. Following this broad discussion, Chapter Five describes syncretism and hybridity more specifically in theatre by means of relevant examples. Taking the discussion further into the realm of application, Chapter Six offers an overview of “workshop theatre”, “translation” and “collage making” as strategies for putting theories of hybridity and syncretism into practice. This is followed (in Chapters Seven, Eight and Nine) by a discussion of the three productions (Hex, Lady Anne and Ekspedisies) as case studies that demonstrate how these theories can be understood in practice. Practical strategies for bridging language divides are foregrounded, such as code switching as an approach for enabling a “co-habitation” of languages; physical theatre as a means for crossing language divides; and the creation of more than one language version of a production as a tactic to accommodate shifting contexts. Following on from the discoveries made in the foregoing chapters, I conclude that theories and practices related to notions of “third space”, “hybridity” and “syncretism” are ideal for creating theatre forms (in the Afrikaans language in particular) that can truly reflect a South African society which is “united in diversity”. The thesis ends by offering suggestions for ways in which new, future identities, can be developed.
- Full Text:
- Date Issued: 2016
Smallholder farmer's adoption decision-making processes in the utilisation of soil conservation practices in South Africa: the case of Qamata Irrigation Scheme, in the Eastern Cape
- Authors: David, Ighodaro Ikponmwosa
- Date: 2016
- Subjects: Qamata Irrigation Scheme (South Africa) Irrigation -- South Africa -- Eastern Cape Farm management -- South Africa -- Decision making , Farms, Small -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10353/1740 , vital:27554
- Description: The goal of this study was to determine the nature and factors influencing smallholder farmers in their adoption decision-making regarding the use of soil conservation practices introduced by extension practitioners in South Africa, using the case of farming at Qamata Irrigation Scheme, Eastern Cape. Using a central argument (thesis statement), the study argued that an adequate understanding and definition of smallholder farmers’ adoption decision-making process is very crucial to solving the problem of soil erosion/ degradation problem amongst smallholder farmers. Adopting the case study research design, information from 70 crop farmers (in a farmer focus group interviews) form the basis of the study. Basic models of analysis were the multiple, probit and logit, as well as the binary logistic regression analyses. According to the empirical results, perception was found very relevant in adoption decision-making, interacting positively and significantly with eight of the seventeen adoption variables chosen for the study. The indication therefore is that age (p<0.050), education (p<0.0030), and marriage (p<0.036), have more potentials to improve farmers’ perception. Similarly, higher farmer incomes (from crops [p<0.017], off-farm [p<0.038] and overall [p<0.011] income) also have a likelihood to improve farmers’ perception regarding soil conservation, for improved adoption. Further indication is that farmers who are aware (p<0.015) of the soil practices introduced by extension are also those who participate in their use (p<0.041). Employing the binary logistic, probit and logit regression models, results suggest that the nature of adoption decision-making processes of smallholder farmers is complex (not straight), being influenced by multiple factors. While age (p<0.099), gender (p<0.031), total income (p<0.081) impacted positively significant on smallholder farmers’ adoption decision-making, marital status (p<0.025), sources of land (p<0.063), length of continuously farming on same piece of land (p<0.013), and level of crop production (p<0.002) impacted negatively. The indication therefore was that older farmers preferred their own practices to the recommended practices by extension, which is in line with literature. Also as expected, more females preferred their own practices to extension recommended, while more males preferred the recommended practices. Similarly, marriage, land ownership, farming continuously on a spot for a long period, as well as increase in the level of crop production, all had a propensity to influence farmers toward the adoption of extension recommended practices as against farmers’ practices. Further results indicate, that farmers’ education (p<0.032), household size (p<0.37), and income (off-farm [p<0.036] and total [p<0.004]), measures used to measure farmers’ livelihood standards in the study, were positively significant in association with adoption. The indication was that, adoption decision-making is potentially capable of improving education level of farmers; increase the size of household, thus providing easy family labour; and as well improve level of income for the farmer. Based on the foregoing, the suggestion therefore is that any technology intervention programme that will succeed must begin with a clear understanding and analysis of farmers’ adoption process. This is better achieved when the adoption process is seen as a four-stage process, where the farmer first forms a view about the innovation (perception stage), and then decides whether or not to use it (adoption stage), as well as how much of the innovation to adopt (level of adoption stage), and finally how much is this innovation going to affect my livelihood (impact of adoption stage). Also, due to the particular relevance of perception in the adoption decision-making process, technology disseminators (extension), researchers and policy makers alike must never conclude on the rejection of any technology, not until factors determining perception of individuals have been well studied. The notion here is that, even at the confirmation stage of the adoption process of an individual adopter, when a rejection is confirmed, for an example, analysing factors of the adopter’s perception at play at the particular time of the innovation in question, could go a long way to redirecting the course of the adoption process of the said individual.
- Full Text:
- Date Issued: 2016
- Authors: David, Ighodaro Ikponmwosa
- Date: 2016
- Subjects: Qamata Irrigation Scheme (South Africa) Irrigation -- South Africa -- Eastern Cape Farm management -- South Africa -- Decision making , Farms, Small -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10353/1740 , vital:27554
- Description: The goal of this study was to determine the nature and factors influencing smallholder farmers in their adoption decision-making regarding the use of soil conservation practices introduced by extension practitioners in South Africa, using the case of farming at Qamata Irrigation Scheme, Eastern Cape. Using a central argument (thesis statement), the study argued that an adequate understanding and definition of smallholder farmers’ adoption decision-making process is very crucial to solving the problem of soil erosion/ degradation problem amongst smallholder farmers. Adopting the case study research design, information from 70 crop farmers (in a farmer focus group interviews) form the basis of the study. Basic models of analysis were the multiple, probit and logit, as well as the binary logistic regression analyses. According to the empirical results, perception was found very relevant in adoption decision-making, interacting positively and significantly with eight of the seventeen adoption variables chosen for the study. The indication therefore is that age (p<0.050), education (p<0.0030), and marriage (p<0.036), have more potentials to improve farmers’ perception. Similarly, higher farmer incomes (from crops [p<0.017], off-farm [p<0.038] and overall [p<0.011] income) also have a likelihood to improve farmers’ perception regarding soil conservation, for improved adoption. Further indication is that farmers who are aware (p<0.015) of the soil practices introduced by extension are also those who participate in their use (p<0.041). Employing the binary logistic, probit and logit regression models, results suggest that the nature of adoption decision-making processes of smallholder farmers is complex (not straight), being influenced by multiple factors. While age (p<0.099), gender (p<0.031), total income (p<0.081) impacted positively significant on smallholder farmers’ adoption decision-making, marital status (p<0.025), sources of land (p<0.063), length of continuously farming on same piece of land (p<0.013), and level of crop production (p<0.002) impacted negatively. The indication therefore was that older farmers preferred their own practices to the recommended practices by extension, which is in line with literature. Also as expected, more females preferred their own practices to extension recommended, while more males preferred the recommended practices. Similarly, marriage, land ownership, farming continuously on a spot for a long period, as well as increase in the level of crop production, all had a propensity to influence farmers toward the adoption of extension recommended practices as against farmers’ practices. Further results indicate, that farmers’ education (p<0.032), household size (p<0.37), and income (off-farm [p<0.036] and total [p<0.004]), measures used to measure farmers’ livelihood standards in the study, were positively significant in association with adoption. The indication was that, adoption decision-making is potentially capable of improving education level of farmers; increase the size of household, thus providing easy family labour; and as well improve level of income for the farmer. Based on the foregoing, the suggestion therefore is that any technology intervention programme that will succeed must begin with a clear understanding and analysis of farmers’ adoption process. This is better achieved when the adoption process is seen as a four-stage process, where the farmer first forms a view about the innovation (perception stage), and then decides whether or not to use it (adoption stage), as well as how much of the innovation to adopt (level of adoption stage), and finally how much is this innovation going to affect my livelihood (impact of adoption stage). Also, due to the particular relevance of perception in the adoption decision-making process, technology disseminators (extension), researchers and policy makers alike must never conclude on the rejection of any technology, not until factors determining perception of individuals have been well studied. The notion here is that, even at the confirmation stage of the adoption process of an individual adopter, when a rejection is confirmed, for an example, analysing factors of the adopter’s perception at play at the particular time of the innovation in question, could go a long way to redirecting the course of the adoption process of the said individual.
- Full Text:
- Date Issued: 2016
Standards and indicators for sustainability in South African businesses
- Authors: Janse van Rensburg, Heidi
- Date: 2016
- Subjects: Sustainable development reporting -- South Africa Economic development -- South Africa
- Language: English
- Type: Thesis , Doctoral , DPhil
- Identifier: http://hdl.handle.net/10948/14334 , vital:27571
- Description: Sustainability reporting is becoming increasingly important, and governments and stock exchanges of many countries require or strongly encourage businesses to provide some level of sustainability reporting. South Africa is one of few emerging market economies and the only country in Africa which show substantial sustainability reporting activities. In South Africa, sustainable development has been recognised at a constitutional and legislative level. Companies listed on the Johannesburg Stock Exchange (JSE) must integrate sustainability reporting with financial reporting, or explain why they are not complying. Establishing a suitable sustainability reporting framework should therefore be part of the strategic integration of sustainability with other aspects of organisational planning and decision-making. This study suggests such a framework of standards and indicators for sustainability reporting in South African businesses, and evaluates it in South African listed companies. Mixed methods research was used in two phases. In phase 1, a critical analysis of the literature produced a framework of standards and indicators to be used as a measure to evaluate sustainability reporting in South Africa. In phase 2, first hand, original data was collected by performing a quantitative content analysis of sustainability reports of 84 companies listed on the Johannesburg stock exchange with the aim to identify standards and indicators that are applied in the content of sustainability reports in South Africa. Quantitative content analysis involves analysing material and then classifying it into various coding units or themes found in the material - it is a systematic way of converting text to numerical variables for quantitative data analysis.
- Full Text:
- Date Issued: 2016
- Authors: Janse van Rensburg, Heidi
- Date: 2016
- Subjects: Sustainable development reporting -- South Africa Economic development -- South Africa
- Language: English
- Type: Thesis , Doctoral , DPhil
- Identifier: http://hdl.handle.net/10948/14334 , vital:27571
- Description: Sustainability reporting is becoming increasingly important, and governments and stock exchanges of many countries require or strongly encourage businesses to provide some level of sustainability reporting. South Africa is one of few emerging market economies and the only country in Africa which show substantial sustainability reporting activities. In South Africa, sustainable development has been recognised at a constitutional and legislative level. Companies listed on the Johannesburg Stock Exchange (JSE) must integrate sustainability reporting with financial reporting, or explain why they are not complying. Establishing a suitable sustainability reporting framework should therefore be part of the strategic integration of sustainability with other aspects of organisational planning and decision-making. This study suggests such a framework of standards and indicators for sustainability reporting in South African businesses, and evaluates it in South African listed companies. Mixed methods research was used in two phases. In phase 1, a critical analysis of the literature produced a framework of standards and indicators to be used as a measure to evaluate sustainability reporting in South Africa. In phase 2, first hand, original data was collected by performing a quantitative content analysis of sustainability reports of 84 companies listed on the Johannesburg stock exchange with the aim to identify standards and indicators that are applied in the content of sustainability reports in South Africa. Quantitative content analysis involves analysing material and then classifying it into various coding units or themes found in the material - it is a systematic way of converting text to numerical variables for quantitative data analysis.
- Full Text:
- Date Issued: 2016
Strategies for the implementation of a total quality management approach for the South African Police Service
- Authors: Wolvaard, Irene Wilhelmina
- Date: 2016
- Subjects: Total quality management in government -- South Africa Organizational effectiveness -- South Africa Police administration -- South Africa
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10948/13171 , vital:27158
- Description: This study focussed on drafting a framework for Total Quality Management (TQM) for the South African Police Service (SAPS) in the Eastern Cape as a public non-profit organisation where quality of services is fast becoming a key organisational imperative. The early pioneers of Quality laid the foundation for Total Quality Management (TQM). The literature review highlighted that TQM has its origins in the manufacturing industry where it has a proven track record, and that the theory could be purposely adapted use by a specific industry, i.e. SAPS. This study extends the applicability of the TQM theory to the SAPS by using a mixed method approach to gather information by means of interviews and questionnaires. A combination of primary and secondary data was used in determining the Critical Success Factors (CSF). The Primary CSF’s were originally identified as Leadership, Strategic Management, Empowerment of employees, Teamwork, Continuous improvement, Customer satisfaction and Culture. The Secondary factors were identified as Communication, Training, Partnership development, Support structures, Systems and Resources, Systems thinking, Selfassessment, Processes; Elimination of barriers, Adoption of a Prevention approach and Change management. Data was analysed using frequency and other means, as well as correlation analysis. After the data was analysed two CSF’s were discarded, i.e. Training and Elimination of Barriers. The results show support for the applicability of the theory to the SAPS. Critical Success Factors were determined and a framework for implementation specifically for this industry, was presented. The study identified Leadership as the most important primary factor with the ultimate goal of meeting the quality expectations as defined by the customer.
- Full Text:
- Date Issued: 2016
- Authors: Wolvaard, Irene Wilhelmina
- Date: 2016
- Subjects: Total quality management in government -- South Africa Organizational effectiveness -- South Africa Police administration -- South Africa
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10948/13171 , vital:27158
- Description: This study focussed on drafting a framework for Total Quality Management (TQM) for the South African Police Service (SAPS) in the Eastern Cape as a public non-profit organisation where quality of services is fast becoming a key organisational imperative. The early pioneers of Quality laid the foundation for Total Quality Management (TQM). The literature review highlighted that TQM has its origins in the manufacturing industry where it has a proven track record, and that the theory could be purposely adapted use by a specific industry, i.e. SAPS. This study extends the applicability of the TQM theory to the SAPS by using a mixed method approach to gather information by means of interviews and questionnaires. A combination of primary and secondary data was used in determining the Critical Success Factors (CSF). The Primary CSF’s were originally identified as Leadership, Strategic Management, Empowerment of employees, Teamwork, Continuous improvement, Customer satisfaction and Culture. The Secondary factors were identified as Communication, Training, Partnership development, Support structures, Systems and Resources, Systems thinking, Selfassessment, Processes; Elimination of barriers, Adoption of a Prevention approach and Change management. Data was analysed using frequency and other means, as well as correlation analysis. After the data was analysed two CSF’s were discarded, i.e. Training and Elimination of Barriers. The results show support for the applicability of the theory to the SAPS. Critical Success Factors were determined and a framework for implementation specifically for this industry, was presented. The study identified Leadership as the most important primary factor with the ultimate goal of meeting the quality expectations as defined by the customer.
- Full Text:
- Date Issued: 2016
Structural bioinformatics studies and tool development related to drug discovery
- Authors: Hatherley, Rowan
- Date: 2016
- Subjects: Structural bioinformatics , Drug development , Natural products -- Databases , Natural products -- Biotechnology , Sequence alignment (Bioinformatics) , Malaria -- Chemotherapy , Heat shock proteins , Plasmodium falciparum
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4164 , http://hdl.handle.net/10962/d1020021
- Description: This thesis is divided into two distinct sections which can be combined under the broad umbrella of structural bioinformatics studies related to drug discovery. The first section involves the establishment of an online South African natural products database. Natural products (NPs) are chemical entities synthesised in nature and are unrivalled in their structural complexity, chemical diversity, and biological specificity, which has long made them crucial to the drug discovery process. South Africa is rich in both plant and marine biodiversity and a great deal of research has gone into isolating compounds from organisms found in this country. However, there is no official database containing this information, making it difficult to access for research purposes. This information was extracted manually from literature to create a database of South African natural products. In order to make the information accessible to the general research community, a website, named “SANCDB”, was built to enable compounds to be quickly and easily searched for and downloaded in a number of different chemical formats. The content of the database was assessed and compared to other established natural product databases. Currently, SANCDB is the only database of natural products in Africa with an online interface. The second section of the thesis was aimed at performing structural characterisation of proteins with the potential to be targeted for antimalarial drug therapy. This looked specifically at 1) The interactions between an exported heat shock protein (Hsp) from Plasmodium falciparum (P. falciparum), PfHsp70-x and various host and exported parasite J proteins, as well as 2) The interface between PfHsp90 and the heat shock organising protein (PfHop). The PfHsp70-x:J protein study provided additional insight into how these two proteins potentially interact. Analysis of the PfHsp90:PfHop also provided a structural insight into the interaction interface between these two proteins and identified residues that could be targeted due to their contribution to the stability of the Hsp90:Hop binding complex and differences between parasite and human proteins. These studies inspired the development of a homology modelling tool, which can be used to assist researchers with homology modelling, while providing them with step-by-step control over the entire process. This thesis presents the establishment of a South African NP database and the development of a homology modelling tool, inspired by protein structural studies. When combined, these two applications have the potential to contribute greatly towards in silico drug discovery research.
- Full Text:
- Date Issued: 2016
- Authors: Hatherley, Rowan
- Date: 2016
- Subjects: Structural bioinformatics , Drug development , Natural products -- Databases , Natural products -- Biotechnology , Sequence alignment (Bioinformatics) , Malaria -- Chemotherapy , Heat shock proteins , Plasmodium falciparum
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4164 , http://hdl.handle.net/10962/d1020021
- Description: This thesis is divided into two distinct sections which can be combined under the broad umbrella of structural bioinformatics studies related to drug discovery. The first section involves the establishment of an online South African natural products database. Natural products (NPs) are chemical entities synthesised in nature and are unrivalled in their structural complexity, chemical diversity, and biological specificity, which has long made them crucial to the drug discovery process. South Africa is rich in both plant and marine biodiversity and a great deal of research has gone into isolating compounds from organisms found in this country. However, there is no official database containing this information, making it difficult to access for research purposes. This information was extracted manually from literature to create a database of South African natural products. In order to make the information accessible to the general research community, a website, named “SANCDB”, was built to enable compounds to be quickly and easily searched for and downloaded in a number of different chemical formats. The content of the database was assessed and compared to other established natural product databases. Currently, SANCDB is the only database of natural products in Africa with an online interface. The second section of the thesis was aimed at performing structural characterisation of proteins with the potential to be targeted for antimalarial drug therapy. This looked specifically at 1) The interactions between an exported heat shock protein (Hsp) from Plasmodium falciparum (P. falciparum), PfHsp70-x and various host and exported parasite J proteins, as well as 2) The interface between PfHsp90 and the heat shock organising protein (PfHop). The PfHsp70-x:J protein study provided additional insight into how these two proteins potentially interact. Analysis of the PfHsp90:PfHop also provided a structural insight into the interaction interface between these two proteins and identified residues that could be targeted due to their contribution to the stability of the Hsp90:Hop binding complex and differences between parasite and human proteins. These studies inspired the development of a homology modelling tool, which can be used to assist researchers with homology modelling, while providing them with step-by-step control over the entire process. This thesis presents the establishment of a South African NP database and the development of a homology modelling tool, inspired by protein structural studies. When combined, these two applications have the potential to contribute greatly towards in silico drug discovery research.
- Full Text:
- Date Issued: 2016