Computational studies in human African trypanosomiasis
- Authors: Muronzi, Tendai
- Date: 2023-10-13
- Subjects: African trypanosomiasis , Apolipoprotein L1 , Docking , Protein-protein interactions , Homology modeling , Tetrahydrofolate dehydrogenase , Pteridine reductase
- Language: English
- Type: Academic theses , Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/431883 , vital:72812 , DOI 10.21504/10962/431885
- Description: Human African trypanosomiasis (HAT) is a neglected tropical disease (NTD) caused by two subspecies of the parasite, namely Trypanosoma brucei (Tb) gambiense (g-HAT) and rhodesiense (r-HAT). HAT is endemic in sub-Saharan countries, where the parasite transmission vectors, tsetse flies, breed. An estimated 70 million people remain at risk of contracting the disease, where the infection is classified as acute or chronic for g-HAT and r-HAT, respectively, with both forms ending in fatal meningoencephalitis when left untreated. Both g-HAT and r-HAT are responsible for widespread fatal epidemics throughout sub-Saharan African history, resulting from the complex molecular interplay between trypanosomes and humans through unique, innate immunity evasion mechanisms. Of interest, the Tbr subspecies expresses a serum resistance-associated protein (SRA), which binds to human serum lytic factor, apolipoprotein L1 (ApoL1), nullifying any trypanocidal activity. In response, ApoL1 (G1 and G2) variants found in humans of sub-Saharan African lineage have been cited for conferring resistance to the r-HAT infection in an interaction that is not fully elucidated In the event of successful infection, current HAT chemotherapeutics are plagued with complexity of administration, poor efficacy, toxicity, and potential drug resistance, highlighting a need for improved approaches. The parasite folate pathway provides a strategic target for alternative anti-trypanosomal drug development as trypanosomatids are folate auxotrophs, requiring host folate for growth and survival. Validated drug targets pteridine reductase (TbPTR1) and dihydrofolate reductase (TbDHFR) are essential for salvaging cofactors folate and folate biopterin crucial to parasite survival, making them viable targets for anti-folate investigation. The overall aims of this thesis were to a) provide insights into the molecular and dynamic basis of the SRA and ApoL1 interplay in HAT infection and b) identify safer and more efficient anti-folate anti-trypanosomal drug alternatives through in silico approaches. To achieve our first aim, in silico structure prediction was applied to generate 3D models of ApoL1 C-terminal variants G0, G1, G1G/M, G2 and G1G2, and four SRA variants retrieved from the NCBI database. The SRA and ApoL1 structures were inspected dynamically to identify the effect of the variants through molecular dynamics (MD) simulations. Dynamic residue network (DRN) analysis of MD trajectories was fundamental in identifying residues playing a vital role in the intramolecular communication of both proteins in the presence of mutations. Protein-protein docking was then applied to calculate plausible SRA-ApoL1 C-terminal wild-type complex structures to further elucidate the nature of SRA-mediated infection. Through MD simulations, twelve SRA-ApoL1 dimeric structures were narrowed down from five to two energetically sound complexes. The two feasible SRA-ApoL1 complexes (1 and 2) exhibited favourable communication observed through DRN analysis, including the retaining key communication residues identified in prior monomer DRN calculations. ApoL1 C-terminal variants were additionally incorporated into SRA-ApoL1 complexes 1 and 2 for further complex dynamics analysis This investigation into the nature of SRA-ApoL1 binding resulted in five primary outcomes: 1) highlighting the intramolecular effects ApoL1 variants have on the stability of the protein, 2) the identification of crucial SRA and ApoL1 communication residues in both monomeric or dimeric form, 3) the isolation of feasible SRA-ApoL1 complexes determined through global and local structural analyses 4) identification of residues crucial to the complex formation and maintenance of SRA-ApoL1, overlapping with those identified in (1), and 5) the minimal dissociative role of the G1 mutations in the complex, but compounding effect of the G2 deletion mutation. Computational modelling and drug repurposing were employed to achieve the thesis's second aim as they drastically cut down the costs involved in drug discovery and provide a more time-efficient screening method through numerous drug candidates. Using high throughput virtual screening, a subset of 2089 approved DrugBank compounds were screened against TbPTR1. The outputs were filtered to 24 viable compounds in 54 binding poses using binding energy and molecular interactions. Through subsequent MD simulations of 200ns, thirteen potential hit compounds were identified. The resultant hit compounds were subjected to further blind docking against TbDHFR and molecular dynamics to identify compounds with the potential for dual inhibition. The filtered subset was also tested in in vitro single concentration and dose-response bioassays to assess inhibitory properties against Trypanosoma brucei, complementing in silico findings. Post-molecular dynamics, four compounds exhibited high stabilities and molecular interactions with both TbPTR1 and TbDHFR, with two presenting favourable results in the in vitro assays. Three compounds additionally shared common structural moieties. In all, the in silico repurposing highlighted drugs characterised by favourable interactions and stabilities in TbPTR1, thus providing (1) a framework for further studies investigating anti-folate HAT compounds and (2) modulatory scaffolds based on identified moieties that can be used for the design of safe anti-folate trypanosomal drugs. , Thesis (PhD) -- Faculty of Science, Biochemistry and Microbiology, 2023
- Full Text:
- Date Issued: 2023-10-13
- Authors: Muronzi, Tendai
- Date: 2023-10-13
- Subjects: African trypanosomiasis , Apolipoprotein L1 , Docking , Protein-protein interactions , Homology modeling , Tetrahydrofolate dehydrogenase , Pteridine reductase
- Language: English
- Type: Academic theses , Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/431883 , vital:72812 , DOI 10.21504/10962/431885
- Description: Human African trypanosomiasis (HAT) is a neglected tropical disease (NTD) caused by two subspecies of the parasite, namely Trypanosoma brucei (Tb) gambiense (g-HAT) and rhodesiense (r-HAT). HAT is endemic in sub-Saharan countries, where the parasite transmission vectors, tsetse flies, breed. An estimated 70 million people remain at risk of contracting the disease, where the infection is classified as acute or chronic for g-HAT and r-HAT, respectively, with both forms ending in fatal meningoencephalitis when left untreated. Both g-HAT and r-HAT are responsible for widespread fatal epidemics throughout sub-Saharan African history, resulting from the complex molecular interplay between trypanosomes and humans through unique, innate immunity evasion mechanisms. Of interest, the Tbr subspecies expresses a serum resistance-associated protein (SRA), which binds to human serum lytic factor, apolipoprotein L1 (ApoL1), nullifying any trypanocidal activity. In response, ApoL1 (G1 and G2) variants found in humans of sub-Saharan African lineage have been cited for conferring resistance to the r-HAT infection in an interaction that is not fully elucidated In the event of successful infection, current HAT chemotherapeutics are plagued with complexity of administration, poor efficacy, toxicity, and potential drug resistance, highlighting a need for improved approaches. The parasite folate pathway provides a strategic target for alternative anti-trypanosomal drug development as trypanosomatids are folate auxotrophs, requiring host folate for growth and survival. Validated drug targets pteridine reductase (TbPTR1) and dihydrofolate reductase (TbDHFR) are essential for salvaging cofactors folate and folate biopterin crucial to parasite survival, making them viable targets for anti-folate investigation. The overall aims of this thesis were to a) provide insights into the molecular and dynamic basis of the SRA and ApoL1 interplay in HAT infection and b) identify safer and more efficient anti-folate anti-trypanosomal drug alternatives through in silico approaches. To achieve our first aim, in silico structure prediction was applied to generate 3D models of ApoL1 C-terminal variants G0, G1, G1G/M, G2 and G1G2, and four SRA variants retrieved from the NCBI database. The SRA and ApoL1 structures were inspected dynamically to identify the effect of the variants through molecular dynamics (MD) simulations. Dynamic residue network (DRN) analysis of MD trajectories was fundamental in identifying residues playing a vital role in the intramolecular communication of both proteins in the presence of mutations. Protein-protein docking was then applied to calculate plausible SRA-ApoL1 C-terminal wild-type complex structures to further elucidate the nature of SRA-mediated infection. Through MD simulations, twelve SRA-ApoL1 dimeric structures were narrowed down from five to two energetically sound complexes. The two feasible SRA-ApoL1 complexes (1 and 2) exhibited favourable communication observed through DRN analysis, including the retaining key communication residues identified in prior monomer DRN calculations. ApoL1 C-terminal variants were additionally incorporated into SRA-ApoL1 complexes 1 and 2 for further complex dynamics analysis This investigation into the nature of SRA-ApoL1 binding resulted in five primary outcomes: 1) highlighting the intramolecular effects ApoL1 variants have on the stability of the protein, 2) the identification of crucial SRA and ApoL1 communication residues in both monomeric or dimeric form, 3) the isolation of feasible SRA-ApoL1 complexes determined through global and local structural analyses 4) identification of residues crucial to the complex formation and maintenance of SRA-ApoL1, overlapping with those identified in (1), and 5) the minimal dissociative role of the G1 mutations in the complex, but compounding effect of the G2 deletion mutation. Computational modelling and drug repurposing were employed to achieve the thesis's second aim as they drastically cut down the costs involved in drug discovery and provide a more time-efficient screening method through numerous drug candidates. Using high throughput virtual screening, a subset of 2089 approved DrugBank compounds were screened against TbPTR1. The outputs were filtered to 24 viable compounds in 54 binding poses using binding energy and molecular interactions. Through subsequent MD simulations of 200ns, thirteen potential hit compounds were identified. The resultant hit compounds were subjected to further blind docking against TbDHFR and molecular dynamics to identify compounds with the potential for dual inhibition. The filtered subset was also tested in in vitro single concentration and dose-response bioassays to assess inhibitory properties against Trypanosoma brucei, complementing in silico findings. Post-molecular dynamics, four compounds exhibited high stabilities and molecular interactions with both TbPTR1 and TbDHFR, with two presenting favourable results in the in vitro assays. Three compounds additionally shared common structural moieties. In all, the in silico repurposing highlighted drugs characterised by favourable interactions and stabilities in TbPTR1, thus providing (1) a framework for further studies investigating anti-folate HAT compounds and (2) modulatory scaffolds based on identified moieties that can be used for the design of safe anti-folate trypanosomal drugs. , Thesis (PhD) -- Faculty of Science, Biochemistry and Microbiology, 2023
- Full Text:
- Date Issued: 2023-10-13
Species diversity and distribution patterns of three freshwater fish genera in southern Africa
- Authors: Mutizwa, Tadiwa Isaac
- Date: 2023-10-13
- Subjects: Uncatalogued
- Language: English
- Type: Academic theses , Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/431896 , vital:72813
- Description: Access restricted. Expected release in 2025. , Thesis (PhD) -- Faculty of Science, Ichthyology and Fisheries Science, 2023
- Full Text:
- Date Issued: 2023-10-13
- Authors: Mutizwa, Tadiwa Isaac
- Date: 2023-10-13
- Subjects: Uncatalogued
- Language: English
- Type: Academic theses , Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/431896 , vital:72813
- Description: Access restricted. Expected release in 2025. , Thesis (PhD) -- Faculty of Science, Ichthyology and Fisheries Science, 2023
- Full Text:
- Date Issued: 2023-10-13
The electrocatalytic activity of metallophthalocyanines and their conjugates with carbon nanomaterials and metal tungstate nanoparticles
- Authors: Ndebele, Nobuhle
- Date: 2023-10-13
- Subjects: Uncatalogued
- Language: English
- Type: Academic theses , Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/431934 , vital:72816 , DOI 10.21504/10962/431933
- Description: In this dissertation, seventeen phthalocyanine complexes were synthesised. Of these, only four are known and have been published. These complexes were synthesised using the conventional statistical condensation method that involves refluxing the phthalonitrile(s) (4-((1,3-bis(dimethylamino)propan-2-yl)oxy)phthalonitrile, 4-(4-carboxyphenoxy)phthalonitrile, 4-(4-acetylphenoxy)phthalonitrile, dimethyl 5-(3,4-dicyanophenoxy)-isophthalate, 4-(4-(tert-butyl)phenoxy)phthalonitrile, 5-phenoxylpicolinic acid phthalonitrile 4-(4-formylphenoxy) phthalonitrile, and 4-(4-(3-oxo-3-phenylprop-1-enyl) phenoxy) phthalonitrile) with the metal salt and 1,8-diazabicyclo[5.4.0]undecane as a catalyst in a high-temperature solvent. And thereafter (when necessary), isolation and purification of the target compounds were achieved through the use of silica column chromatography. These compounds were characterised using various analytical techniques such as; ultraviolet-visible absorption, mass spectroscopy, and Fourier transform infrared spectra and elemental analysis. These techniques proved that the complexes were successfully synthesised and isolated as pure compounds. Carbon-based (graphene quantum dots and nitrogen-doped graphene quantum dots) and metal oxide (bismuth tungsten oxide and nickel tungsten oxide) nanomaterials were synthesised. Together with the purchased single-walled carbon nanotubes, these nanomaterials were conjugated to some of the MPc complexes via non-covalent (carbon-based nanomaterials) and covalent (metal oxides) linkage forming hybrid materials. These nanomaterials and hybrids were characterised using various analytical methods (ultraviolet-visible absorption, X-ray diffraction, Raman spectroscopy, thermographic analysis, and dynamic light scattering). Nanomaterials were utilised herein to determine their effect on the properties of MPc complexes and provide a synergistic effect in the hope of enhancing these properties. All complexes synthesised in this work (MPcs, nanomaterials and hybrids) were employed as electrocatalysts in electrochemical sensing. These electrocatalysts were embedded onto the glassy carbon electrode via an adsorption method known as drop-casting. The modified electrode surfaces were characterised using cyclic voltammetry, electrochemical impedance spectroscopy and scanning electrochemical microscopy to determine various electrochemical parameters. These electrocatalysts were used in the detection of either nitrite, catechol and/or dopamine. The detection limits, sensitivities, kinetics and catalytic constants were among other parameters determined for each electrocatalyst. These electrocatalysts proved to be stable electrocatalysts that could potentially be used for practical applications. The determined parameters were comparable and sometimes better than those obtained in literature. , Thesis (PhD) -- Faculty of Science, Chemistry, 2023
- Full Text:
- Date Issued: 2023-10-13
- Authors: Ndebele, Nobuhle
- Date: 2023-10-13
- Subjects: Uncatalogued
- Language: English
- Type: Academic theses , Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/431934 , vital:72816 , DOI 10.21504/10962/431933
- Description: In this dissertation, seventeen phthalocyanine complexes were synthesised. Of these, only four are known and have been published. These complexes were synthesised using the conventional statistical condensation method that involves refluxing the phthalonitrile(s) (4-((1,3-bis(dimethylamino)propan-2-yl)oxy)phthalonitrile, 4-(4-carboxyphenoxy)phthalonitrile, 4-(4-acetylphenoxy)phthalonitrile, dimethyl 5-(3,4-dicyanophenoxy)-isophthalate, 4-(4-(tert-butyl)phenoxy)phthalonitrile, 5-phenoxylpicolinic acid phthalonitrile 4-(4-formylphenoxy) phthalonitrile, and 4-(4-(3-oxo-3-phenylprop-1-enyl) phenoxy) phthalonitrile) with the metal salt and 1,8-diazabicyclo[5.4.0]undecane as a catalyst in a high-temperature solvent. And thereafter (when necessary), isolation and purification of the target compounds were achieved through the use of silica column chromatography. These compounds were characterised using various analytical techniques such as; ultraviolet-visible absorption, mass spectroscopy, and Fourier transform infrared spectra and elemental analysis. These techniques proved that the complexes were successfully synthesised and isolated as pure compounds. Carbon-based (graphene quantum dots and nitrogen-doped graphene quantum dots) and metal oxide (bismuth tungsten oxide and nickel tungsten oxide) nanomaterials were synthesised. Together with the purchased single-walled carbon nanotubes, these nanomaterials were conjugated to some of the MPc complexes via non-covalent (carbon-based nanomaterials) and covalent (metal oxides) linkage forming hybrid materials. These nanomaterials and hybrids were characterised using various analytical methods (ultraviolet-visible absorption, X-ray diffraction, Raman spectroscopy, thermographic analysis, and dynamic light scattering). Nanomaterials were utilised herein to determine their effect on the properties of MPc complexes and provide a synergistic effect in the hope of enhancing these properties. All complexes synthesised in this work (MPcs, nanomaterials and hybrids) were employed as electrocatalysts in electrochemical sensing. These electrocatalysts were embedded onto the glassy carbon electrode via an adsorption method known as drop-casting. The modified electrode surfaces were characterised using cyclic voltammetry, electrochemical impedance spectroscopy and scanning electrochemical microscopy to determine various electrochemical parameters. These electrocatalysts were used in the detection of either nitrite, catechol and/or dopamine. The detection limits, sensitivities, kinetics and catalytic constants were among other parameters determined for each electrocatalyst. These electrocatalysts proved to be stable electrocatalysts that could potentially be used for practical applications. The determined parameters were comparable and sometimes better than those obtained in literature. , Thesis (PhD) -- Faculty of Science, Chemistry, 2023
- Full Text:
- Date Issued: 2023-10-13
An efficient approach for the synthesis of dolutegravir and its analogue exploiting flow chemistry
- Authors: Nqeketo, Sinazo
- Date: 2023-04
- Subjects: HIV (Viruses) – Enzymes –Inhibitors , Antiviral agents -- South Africa
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/${Handle} , vital:70635
- Description: Africa has the highest Human Immunodeficiency Virus (HIV) prevalence in the world and has invested heavily in running its HIV programmes and conducting research of medical significance. Despite efforts in combating this disease the production, distribution, cost, and availability of antiretroviral (ARV) generics remains a major problem as they are imported from China and India. Exploring the recently emerged “enabling technique”, namely flow chemistry in the production of APIs has gained a lot of attention. This study was devoted on exploring the application of flow chemistry on the synthesis of a newly approved anti-HIV drug dolutegravir (DTG); an integrase inhibitor with a high genetic barrier to resistance with a daily dosing scheduled compared to other ARVs and its third-generation inhibitor analogue, cabotegravir. Chapter one covers a comprehensive background and literature review of the HIV epidemic, an introduction of antiretroviral therapy as well as detailed dolutegravir and cabotegravir synthesis. A brief introduction of continuous flow technology with its advantages and disadvantages is discussed in this chapter. The efficient seven-step continuous flow procedure afforded dolutegravir and cabotegravir in improved reaction times and yields compared to the traditional batch procedure was demonstrated. The significant advantage of this flow process includes the reduction of the overall reaction time from step one to step seven, from prolonged 68 hours in batch to 34 minutes. The overall yield of each reaction step improved dramatically upon flow optimization. The yields of the second step (selective ester hydrolysis), fourth step (cyclization) and fifth step (amidation) increased from 64 %, 40 % and 33 % in batch to 98 %, 71 % and 100 % yield by HPLC respectively. Other than improved yields and residence times which was aided advantages of microreactor technology including intensive mixing, the flow process is also much better because it is cost effective. Most importantly, a novel process on the formation of pyridinone intermediate using ion-exchange resin catalysts towards the synthesis of dolutegravir and cabotegravir was described in this study , Thesis (PhD) -- Faculty of Science, School of Biomolecular and Chemical Science, 2023
- Full Text:
- Date Issued: 2023-04
- Authors: Nqeketo, Sinazo
- Date: 2023-04
- Subjects: HIV (Viruses) – Enzymes –Inhibitors , Antiviral agents -- South Africa
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/${Handle} , vital:70635
- Description: Africa has the highest Human Immunodeficiency Virus (HIV) prevalence in the world and has invested heavily in running its HIV programmes and conducting research of medical significance. Despite efforts in combating this disease the production, distribution, cost, and availability of antiretroviral (ARV) generics remains a major problem as they are imported from China and India. Exploring the recently emerged “enabling technique”, namely flow chemistry in the production of APIs has gained a lot of attention. This study was devoted on exploring the application of flow chemistry on the synthesis of a newly approved anti-HIV drug dolutegravir (DTG); an integrase inhibitor with a high genetic barrier to resistance with a daily dosing scheduled compared to other ARVs and its third-generation inhibitor analogue, cabotegravir. Chapter one covers a comprehensive background and literature review of the HIV epidemic, an introduction of antiretroviral therapy as well as detailed dolutegravir and cabotegravir synthesis. A brief introduction of continuous flow technology with its advantages and disadvantages is discussed in this chapter. The efficient seven-step continuous flow procedure afforded dolutegravir and cabotegravir in improved reaction times and yields compared to the traditional batch procedure was demonstrated. The significant advantage of this flow process includes the reduction of the overall reaction time from step one to step seven, from prolonged 68 hours in batch to 34 minutes. The overall yield of each reaction step improved dramatically upon flow optimization. The yields of the second step (selective ester hydrolysis), fourth step (cyclization) and fifth step (amidation) increased from 64 %, 40 % and 33 % in batch to 98 %, 71 % and 100 % yield by HPLC respectively. Other than improved yields and residence times which was aided advantages of microreactor technology including intensive mixing, the flow process is also much better because it is cost effective. Most importantly, a novel process on the formation of pyridinone intermediate using ion-exchange resin catalysts towards the synthesis of dolutegravir and cabotegravir was described in this study , Thesis (PhD) -- Faculty of Science, School of Biomolecular and Chemical Science, 2023
- Full Text:
- Date Issued: 2023-04
An evaluation of the effectiveness of area-based conservation interventions in avoiding biodiversity loss in South Africa
- Authors: Von Staden, Lize
- Date: 2023-04
- Subjects: Environmental policy , Conservation of natural resources -- Government policy -- South Africa
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10948/61115 , vital:69762
- Description: Counterfactual impact evaluation studies form an important evidence base for the effectiveness of conservation projects, programs, and policies (collectively referred to as conservation interventions). In South Africa, counterfactual impact evaluation methods have rarely been applied to local conservation interventions, and therefore evidence for the effectiveness of key strategic national conservation approaches is lacking. This study evaluated three area-based interventions that together aim to avoid the loss of areas most important for the persistence of biodiversity in the terrestrial realm as evidence towards the effectiveness of South Africa’s landscape approach to biodiversity conservation. The first intervention, South Africa’s National Protected Area Expansion Strategy (NPAES), set ambitious targets to double the extent of South Africa’s protected area network while ensuring that the expansion preferentially occurs in areas of under-represented biodiversity. The strategy was evaluated in terms of its effectiveness in guiding protected area expansion towards more equitable representation of South Africa’s biodiversity through an assessment of changes in indicators of protected area expansion decision-making before and after the implementation of the strategy. The second intervention is the use of maps of biodiversity priorities to guide land use change decisions outside protected areas. Impact was evaluated as avoided loss of Critical Biodiversity Areas (CBAs), which need to remain in a natural condition to meet in situ conservation targets for species, ecosystems, and ecological processes. Avoided loss in CBAs was benchmarked against avoided loss in protected areas, to contextualize the effectiveness of land use planning as a conservation intervention. Lastly, the effectiveness of stricter land use regulations for threatened ecosystems to reduce land conversion pressure on these ecosystems was evaluated. Key findings were that protected areas are highly effective conservation interventions where they can be implemented, but their capacity for conservation impact is limited by severe constraints on strategic expansion. , Thesis (PhD) -- Faculty of Science, School of Environmental Sciences, 2023
- Full Text:
- Date Issued: 2023-04
- Authors: Von Staden, Lize
- Date: 2023-04
- Subjects: Environmental policy , Conservation of natural resources -- Government policy -- South Africa
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10948/61115 , vital:69762
- Description: Counterfactual impact evaluation studies form an important evidence base for the effectiveness of conservation projects, programs, and policies (collectively referred to as conservation interventions). In South Africa, counterfactual impact evaluation methods have rarely been applied to local conservation interventions, and therefore evidence for the effectiveness of key strategic national conservation approaches is lacking. This study evaluated three area-based interventions that together aim to avoid the loss of areas most important for the persistence of biodiversity in the terrestrial realm as evidence towards the effectiveness of South Africa’s landscape approach to biodiversity conservation. The first intervention, South Africa’s National Protected Area Expansion Strategy (NPAES), set ambitious targets to double the extent of South Africa’s protected area network while ensuring that the expansion preferentially occurs in areas of under-represented biodiversity. The strategy was evaluated in terms of its effectiveness in guiding protected area expansion towards more equitable representation of South Africa’s biodiversity through an assessment of changes in indicators of protected area expansion decision-making before and after the implementation of the strategy. The second intervention is the use of maps of biodiversity priorities to guide land use change decisions outside protected areas. Impact was evaluated as avoided loss of Critical Biodiversity Areas (CBAs), which need to remain in a natural condition to meet in situ conservation targets for species, ecosystems, and ecological processes. Avoided loss in CBAs was benchmarked against avoided loss in protected areas, to contextualize the effectiveness of land use planning as a conservation intervention. Lastly, the effectiveness of stricter land use regulations for threatened ecosystems to reduce land conversion pressure on these ecosystems was evaluated. Key findings were that protected areas are highly effective conservation interventions where they can be implemented, but their capacity for conservation impact is limited by severe constraints on strategic expansion. , Thesis (PhD) -- Faculty of Science, School of Environmental Sciences, 2023
- Full Text:
- Date Issued: 2023-04
An exploration of the Participatory Guarantee System (PGS) facilitating the growth and certification of small-scale organic farmers: Giyani, Garden Route and Overberg case studies
- Authors: Mashele,N’wa-Jama
- Date: 2023-04
- Subjects: Organic farming – Case studies --South Africa , Organic farming research
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10948/60741 , vital:66574
- Description: In this study, I evaluated the Participatory Guarantee System (PGS) as a framework to support the growth and certification of small-scale organic farmers. I used the interpretivism and constructivism lenses to understand the PGS from the perspective of members of three PGS groups. The research was qualitative, treating the three PGS groups as case studies. I collected data using focus groups, semi-structured interviews, questionnaires, field notes and observations. The theoretical frameworks that guided the research and data analysis were Socio-ecological Systems (SES) based principles and the Multi-Level-Perspective (MLP) framework. The data were analysed using Atlas.ti content analysis software. The key results were grouped into four themes: capacity; market and logistics; learning process; and disturbance, shock and stress. The theme of ‘capacity’ dealt with the functioning of a PGS, where three categories were identified: group composition and capacity; resource limitations and institutional support; marketing and consumer education. The more diversity in age, education and culture of PGS stakeholders, the better performance and chances of continuity and propagation. PGS has limited capacity partly due to its voluntary nature and infancy. It needs institutional support to grow and be useful for members. Department of Agriculture extension officers knew little about organic farming, thus limiting their engagement and assistance to such farmers. The theme of ‘market and logistics’ looked at the various factors that influence the farmers’ market reach. The perception from the members was that there was minimal consumer awareness about organic agriculture and the PGS. The marketing of organic produce relied largely on the individual farmer’s efforts and ability to search for and secure markets. The theme of the ‘learning process’ was categorised into learning and knowledge exchange. Members of the PGS groups highly regarded the invaluable knowledge shared through farm visits and online platforms, such as their WhatsApp groups. This knowledge improved and informed their farming techniques and led to the growth of v their skill base and experimentation. They viewed the way knowledge was exchanged as non-threatening and highly useful. The fourth theme of ‘disturbance, shock and stress’ dealt with the effects of COVID19. The three groups were all affected by lockdown restrictions (at the time of data collection) and were initially cut off from their usual markets. This led to a loss of income, loss of farm staff and a loss of the desired growth of the farms. The group’s diverse farming practices bolstered their resilience, enabling them to adapt and try alternative marketing strategies. , Thesis (MSc) -- Faculty of Science, School of Natural Resource Management, 2023
- Full Text:
- Date Issued: 2023-04
- Authors: Mashele,N’wa-Jama
- Date: 2023-04
- Subjects: Organic farming – Case studies --South Africa , Organic farming research
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10948/60741 , vital:66574
- Description: In this study, I evaluated the Participatory Guarantee System (PGS) as a framework to support the growth and certification of small-scale organic farmers. I used the interpretivism and constructivism lenses to understand the PGS from the perspective of members of three PGS groups. The research was qualitative, treating the three PGS groups as case studies. I collected data using focus groups, semi-structured interviews, questionnaires, field notes and observations. The theoretical frameworks that guided the research and data analysis were Socio-ecological Systems (SES) based principles and the Multi-Level-Perspective (MLP) framework. The data were analysed using Atlas.ti content analysis software. The key results were grouped into four themes: capacity; market and logistics; learning process; and disturbance, shock and stress. The theme of ‘capacity’ dealt with the functioning of a PGS, where three categories were identified: group composition and capacity; resource limitations and institutional support; marketing and consumer education. The more diversity in age, education and culture of PGS stakeholders, the better performance and chances of continuity and propagation. PGS has limited capacity partly due to its voluntary nature and infancy. It needs institutional support to grow and be useful for members. Department of Agriculture extension officers knew little about organic farming, thus limiting their engagement and assistance to such farmers. The theme of ‘market and logistics’ looked at the various factors that influence the farmers’ market reach. The perception from the members was that there was minimal consumer awareness about organic agriculture and the PGS. The marketing of organic produce relied largely on the individual farmer’s efforts and ability to search for and secure markets. The theme of the ‘learning process’ was categorised into learning and knowledge exchange. Members of the PGS groups highly regarded the invaluable knowledge shared through farm visits and online platforms, such as their WhatsApp groups. This knowledge improved and informed their farming techniques and led to the growth of v their skill base and experimentation. They viewed the way knowledge was exchanged as non-threatening and highly useful. The fourth theme of ‘disturbance, shock and stress’ dealt with the effects of COVID19. The three groups were all affected by lockdown restrictions (at the time of data collection) and were initially cut off from their usual markets. This led to a loss of income, loss of farm staff and a loss of the desired growth of the farms. The group’s diverse farming practices bolstered their resilience, enabling them to adapt and try alternative marketing strategies. , Thesis (MSc) -- Faculty of Science, School of Natural Resource Management, 2023
- Full Text:
- Date Issued: 2023-04
Billing system, communication strategies, and organisation change in Zimbabwe: the case of telone customers’ postpaid to prepaid migration
- Authors: Dube, Sizalobuhle
- Date: 2023-04
- Subjects: Communication , Organizational change , Organizational change -- Management
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10353/27336 , vital:66942
- Description: This study investigated the effectiveness of the communication strategies used to implement the migration of telephone services from post-paid to prepaid billing at TelOne Zimbabwe. This study adopted the Freeman‟s stakeholder theory and the Lewin‟s change model to analyse the factors that influenced the effectiveness of the communication strategies used by TelOne before, during and after the change implementation as a way to communicate the initiative with its stakeholders. A qualitative approach was utilised and the key research methods used included document analysis, participant observation, as well as 21 face-to-face and 79 telephonic semi-structured interviews conducted with respondents from among TelOne managers, employees and the customers. The documents and respondents were purposively sampled based on the researcher‟s knowledge of their relevance in the study. The findings revealed several factors that mired effective change communication strategies such as company image, stakeholder recognition and communication centralisation. To curb these communication challenges, the study proposes Thrive organisational communication change model TOCC that encourages organisations to communicate the initiative to its relevant internal and external stakeholders considering their views and addressing factors that might hinder effective communication as a strategy to enhance successful change management. , Thesis (PhD) -- Faculty of Social Sciences and Humanities, 2023
- Full Text:
- Date Issued: 2023-04
- Authors: Dube, Sizalobuhle
- Date: 2023-04
- Subjects: Communication , Organizational change , Organizational change -- Management
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10353/27336 , vital:66942
- Description: This study investigated the effectiveness of the communication strategies used to implement the migration of telephone services from post-paid to prepaid billing at TelOne Zimbabwe. This study adopted the Freeman‟s stakeholder theory and the Lewin‟s change model to analyse the factors that influenced the effectiveness of the communication strategies used by TelOne before, during and after the change implementation as a way to communicate the initiative with its stakeholders. A qualitative approach was utilised and the key research methods used included document analysis, participant observation, as well as 21 face-to-face and 79 telephonic semi-structured interviews conducted with respondents from among TelOne managers, employees and the customers. The documents and respondents were purposively sampled based on the researcher‟s knowledge of their relevance in the study. The findings revealed several factors that mired effective change communication strategies such as company image, stakeholder recognition and communication centralisation. To curb these communication challenges, the study proposes Thrive organisational communication change model TOCC that encourages organisations to communicate the initiative to its relevant internal and external stakeholders considering their views and addressing factors that might hinder effective communication as a strategy to enhance successful change management. , Thesis (PhD) -- Faculty of Social Sciences and Humanities, 2023
- Full Text:
- Date Issued: 2023-04
Effect of a school-based health intervention on the non-communicable disease risk status of schoolchildren from disadvantaged communities
- Authors: Dolley, Danielle
- Date: 2023-04
- Subjects: school-based health intervention , Non-communicable diseases , Cardiovascular diseases
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10948/66388 , vital:75063
- Description: Background: Non-communicable diseases (NCDs) such as cardiovascular diseases (CVDs) and dyslipidaemia are a global public health concern, but more so in low- income countries where the underprivileged are exposed to unhealthy lifestyle practices with limited access to primary health care. Poor dietary habits and physical inactivity have also led to the unprecedented rise of NCD risk factors among school- aged children, which places them at greater risk of disease later in life. These NCDs are largely driven by obesity which has continued to rise in sub-Saharan Africa. However, high levels of undernutrition (such as stunting, underweight and wasting) among children are also present, thereby translating to a dual burden of malnutrition. Promoting regular physical activity (PA) among children is crucial for the health of future generations as it assists in weight reduction, improves insulin sensitivity, reduces blood pressure and is associated with good health and wellbeing. However, physical education (PE), the most obvious vehicle to develop the motor abilities of children, creating opportunities for their sports skills development and educating learners about the importance of PA as a lifestyle, has long been overlooked since the transformation of the South African school curriculum. Furthermore, many in-service PE teachers were not trained to teach the new multi-disciplinary Life Skills and Life Orientation subjects, of which PE forms a small part. Evidence shows that many PE teachers lack the content knowledge and practical skills to implement the subject, which raises the question of how many children, especially those in low-income communities, are participating in quality PE needed to foster healthy lifestyles and prevent the risk of NCDs. Therefore, this study aimed to investigate the effect of a 20- week school-based health intervention on NCD risk factors of primary schoolchildren from low-income schools in Gqeberha, South Africa. Methods: A cluster randomised control trial was used to test a 20-week intervention, which included three components, namely [1] the KaziKidz toolkit (comprised of pre- prepared PE, health, hygiene and nutrition lessons, equipment for PE, and painted games) [2] a PE coach (human movement science graduate to assist teachers) and [3]two 90-min training workshops. Eight schools were randomly selected to participatein the study: four intervention schools received the KaziKidz toolkit, while the externalsupport components were staggered across three intervention schools, and the Chapter 1: Introduction 2 remaining four schools served as the control group. Altogether 961 children (491 boys and 511 girls) from grades 4 to 6 (8 - 13 years old, M=10.88±1.19 yrs) participated In the study. Demographic information and socio-economic status were captured with a questionnaire. Further measures included height, weight, waist circumference, blood pressure, glycated haemoglobin, total cholesterol, high-density lipoprotein cholesterol, low-density lipoprotein cholesterol, accelerometer-based PA and cardiorespiratory fitness (CRF). Results: Cross-sectional baseline data showed that 43.1% of the sample presented with at least one NCD risk factor, and 17% presented with an elevated clustered risk score (CRS). In addition, higher CRF and moderate to vigorous PA (MVPA) were associated with a lowered CRS whereby an elevated CRS was halved for every 49 min increase in MVPA (95% CI 27 - 224) or every 2.17 ml/kg/min increase in CRF, as determined via estimated VO2max (95% CI 1.66 - 3.12). Overall, 13% of the cohort were underweight, 12% overweight, 7% obese, and 64% engaged in an average of 60 min MVPA per day. The results also identified an inverse association between body mass index categories and the total duration of MVPA achieved per day as children categorised as underweight to normal‐weight (boys: OR = 3.89, 95% CI: 2.18 - 6.93; girls: OR =1.78, 95% CI: 1.13 - 2.80) were more likely to engage in 60 min per day of MVPA than overweight to obese children. Finally, the school-based health intervention results revealed improvements in children's NCD risk factors and increased MVPA levels when the intervention conditions included the workshops and, in some cases, the PE coach. The KaziKidz toolkit (on its own) showed little to no improvements in NCD risk factors and MVPA levels. Conclusion: School-based health interventions have the potential to improve the NCD risk factors of children attending low-income schools in South Africa. These findings also add to our understanding of implementing interventions in settings where teachers are not sufficiently trained to teach PE. Therefore, school-based health interventions, including a toolkit, should be accompanied by workshops to equip educators with the necessary tools to confidently facilitate PE lessons and integrate a range of PE activities into their classrooms. Future research is recommended to determine the long-term sustainability of school-based health interventions and the long-term post-intervention impact on NCD risk factors. , Thesis (PhD) -- Faculty of Health Science, Department of Human Movement Science, 2023
- Full Text:
- Date Issued: 2023-04
- Authors: Dolley, Danielle
- Date: 2023-04
- Subjects: school-based health intervention , Non-communicable diseases , Cardiovascular diseases
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10948/66388 , vital:75063
- Description: Background: Non-communicable diseases (NCDs) such as cardiovascular diseases (CVDs) and dyslipidaemia are a global public health concern, but more so in low- income countries where the underprivileged are exposed to unhealthy lifestyle practices with limited access to primary health care. Poor dietary habits and physical inactivity have also led to the unprecedented rise of NCD risk factors among school- aged children, which places them at greater risk of disease later in life. These NCDs are largely driven by obesity which has continued to rise in sub-Saharan Africa. However, high levels of undernutrition (such as stunting, underweight and wasting) among children are also present, thereby translating to a dual burden of malnutrition. Promoting regular physical activity (PA) among children is crucial for the health of future generations as it assists in weight reduction, improves insulin sensitivity, reduces blood pressure and is associated with good health and wellbeing. However, physical education (PE), the most obvious vehicle to develop the motor abilities of children, creating opportunities for their sports skills development and educating learners about the importance of PA as a lifestyle, has long been overlooked since the transformation of the South African school curriculum. Furthermore, many in-service PE teachers were not trained to teach the new multi-disciplinary Life Skills and Life Orientation subjects, of which PE forms a small part. Evidence shows that many PE teachers lack the content knowledge and practical skills to implement the subject, which raises the question of how many children, especially those in low-income communities, are participating in quality PE needed to foster healthy lifestyles and prevent the risk of NCDs. Therefore, this study aimed to investigate the effect of a 20- week school-based health intervention on NCD risk factors of primary schoolchildren from low-income schools in Gqeberha, South Africa. Methods: A cluster randomised control trial was used to test a 20-week intervention, which included three components, namely [1] the KaziKidz toolkit (comprised of pre- prepared PE, health, hygiene and nutrition lessons, equipment for PE, and painted games) [2] a PE coach (human movement science graduate to assist teachers) and [3]two 90-min training workshops. Eight schools were randomly selected to participatein the study: four intervention schools received the KaziKidz toolkit, while the externalsupport components were staggered across three intervention schools, and the Chapter 1: Introduction 2 remaining four schools served as the control group. Altogether 961 children (491 boys and 511 girls) from grades 4 to 6 (8 - 13 years old, M=10.88±1.19 yrs) participated In the study. Demographic information and socio-economic status were captured with a questionnaire. Further measures included height, weight, waist circumference, blood pressure, glycated haemoglobin, total cholesterol, high-density lipoprotein cholesterol, low-density lipoprotein cholesterol, accelerometer-based PA and cardiorespiratory fitness (CRF). Results: Cross-sectional baseline data showed that 43.1% of the sample presented with at least one NCD risk factor, and 17% presented with an elevated clustered risk score (CRS). In addition, higher CRF and moderate to vigorous PA (MVPA) were associated with a lowered CRS whereby an elevated CRS was halved for every 49 min increase in MVPA (95% CI 27 - 224) or every 2.17 ml/kg/min increase in CRF, as determined via estimated VO2max (95% CI 1.66 - 3.12). Overall, 13% of the cohort were underweight, 12% overweight, 7% obese, and 64% engaged in an average of 60 min MVPA per day. The results also identified an inverse association between body mass index categories and the total duration of MVPA achieved per day as children categorised as underweight to normal‐weight (boys: OR = 3.89, 95% CI: 2.18 - 6.93; girls: OR =1.78, 95% CI: 1.13 - 2.80) were more likely to engage in 60 min per day of MVPA than overweight to obese children. Finally, the school-based health intervention results revealed improvements in children's NCD risk factors and increased MVPA levels when the intervention conditions included the workshops and, in some cases, the PE coach. The KaziKidz toolkit (on its own) showed little to no improvements in NCD risk factors and MVPA levels. Conclusion: School-based health interventions have the potential to improve the NCD risk factors of children attending low-income schools in South Africa. These findings also add to our understanding of implementing interventions in settings where teachers are not sufficiently trained to teach PE. Therefore, school-based health interventions, including a toolkit, should be accompanied by workshops to equip educators with the necessary tools to confidently facilitate PE lessons and integrate a range of PE activities into their classrooms. Future research is recommended to determine the long-term sustainability of school-based health interventions and the long-term post-intervention impact on NCD risk factors. , Thesis (PhD) -- Faculty of Health Science, Department of Human Movement Science, 2023
- Full Text:
- Date Issued: 2023-04
Evaluation of the toxicity of secondary metabolites in Solanum incanum L. to advance community knowledge
- Authors: Zivanayi, William
- Date: 2023-04
- Subjects: Solanum -- Zimbabwe , Pesticides -- Toxicology , Medicinal plants
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10948/61018 , vital:69686
- Description: The effects of pests and the need to produce adequate food have influenced small-scale farmers in disadvantaged communities to adopt and utilise natural plant pesticides to improve harvests in many Southern African Development Communities. However, the phytochemistry associated with these indigenous plants’ pesticide activity still needs to be explored. The lack of evidence of scientific knowledge of the plant species has caused a lot of health issues among the users of indigenous plant pesticides. Solanum incanum is among the plants utilised to control cabbage aphids in Mkoba village, Zimbabwe. Solanum species are known for their steroidal compounds which comprise glycoalkaloids and saponins. This study evaluated the knowledge, opinions, and attitudes of the vegetable peasant farming community in Gweru regarding their use of the indigenous plant (S. incanum) as a pesticide. The study also reported the phytochemical profiling, structural characterisation of the isolated compounds, and biological and pesticidal activity evaluation of phytochemicals isolated from S. incanum. A descriptive survey was carried out to assess the knowledge, attitude, and practices of a conveniently sampled group of vegetable farmers in Mkoba village who use S. incanum as a pesticide. Forty-nine respondents comprised of 19 males and 30 females of ages ranging from 15 to above 60 years took part in the study by answering an open and closed-ended questionnaire. The survey revealed that parents and neighbours were instrumental in disseminating pesticidal information in the community. Brassica napus were the most grown.vegetable and vulnerable to cabbage aphids. Mixed opinions amongst the respondents varied regarding the health and environmental impact of S. incanum as a pesticide. Seventy-five percent (75%) of the respondents supported the use of S. incanum as a pesticide whilst 25% claimed that the use of S. incanum was the source of the health problems experienced in the community. The survey demonstrated that (45)91% of the farmers displayed poor practices regarding the disposal of empty pesticide containers and the use of personal protective clothing. The most prevalent symptoms in the community were skin rash, nausea, headache, and poor vision and these symptoms were common in the age group 30 to 60 years. , Thesis (PhD) -- Faculty of Science, School of biomolecular and Chemical Sciences, 2023
- Full Text:
- Date Issued: 2023-04
- Authors: Zivanayi, William
- Date: 2023-04
- Subjects: Solanum -- Zimbabwe , Pesticides -- Toxicology , Medicinal plants
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10948/61018 , vital:69686
- Description: The effects of pests and the need to produce adequate food have influenced small-scale farmers in disadvantaged communities to adopt and utilise natural plant pesticides to improve harvests in many Southern African Development Communities. However, the phytochemistry associated with these indigenous plants’ pesticide activity still needs to be explored. The lack of evidence of scientific knowledge of the plant species has caused a lot of health issues among the users of indigenous plant pesticides. Solanum incanum is among the plants utilised to control cabbage aphids in Mkoba village, Zimbabwe. Solanum species are known for their steroidal compounds which comprise glycoalkaloids and saponins. This study evaluated the knowledge, opinions, and attitudes of the vegetable peasant farming community in Gweru regarding their use of the indigenous plant (S. incanum) as a pesticide. The study also reported the phytochemical profiling, structural characterisation of the isolated compounds, and biological and pesticidal activity evaluation of phytochemicals isolated from S. incanum. A descriptive survey was carried out to assess the knowledge, attitude, and practices of a conveniently sampled group of vegetable farmers in Mkoba village who use S. incanum as a pesticide. Forty-nine respondents comprised of 19 males and 30 females of ages ranging from 15 to above 60 years took part in the study by answering an open and closed-ended questionnaire. The survey revealed that parents and neighbours were instrumental in disseminating pesticidal information in the community. Brassica napus were the most grown.vegetable and vulnerable to cabbage aphids. Mixed opinions amongst the respondents varied regarding the health and environmental impact of S. incanum as a pesticide. Seventy-five percent (75%) of the respondents supported the use of S. incanum as a pesticide whilst 25% claimed that the use of S. incanum was the source of the health problems experienced in the community. The survey demonstrated that (45)91% of the farmers displayed poor practices regarding the disposal of empty pesticide containers and the use of personal protective clothing. The most prevalent symptoms in the community were skin rash, nausea, headache, and poor vision and these symptoms were common in the age group 30 to 60 years. , Thesis (PhD) -- Faculty of Science, School of biomolecular and Chemical Sciences, 2023
- Full Text:
- Date Issued: 2023-04
Experiences of youths participating in combination social protection and HIV prevention programme in resource constrained settings of Gauteng Province in South Africa: a collective case study design
- Authors: Zibengwa, Enock
- Date: 2023-04
- Subjects: HIV infections -- Prevention , HIV (Viruses) , HIV infections -- Africa
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10353/27347 , vital:66944
- Description: South Africa continues to experience unacceptably high Human Immunodeficiency Virus HIV incidence rates among youths aged 15 to 24 years. Remarkably, this is despite the numerous youth HIV prevention programmes that have been implemented in the country. Unfortunately, the programmes have not significantly curbed the spread of HIV due to the partial and fragmented nature of their implementation. The programmes are also observed to be weak in addressing complex economic factors recognised as important structural drivers for vulnerabilities that put youths at risk of HIV infection. To address this challenge, there is increased adoption and implementation of the Combination Social Protection introduced in this research as the CSP by Non-Governmental Organisations NGOs. The CSP is a youth empowerment programming strategy whose critical foundations are entrenched in combining economic strengthening interventions and HIV prevention education. CSP could provide youths with a set of indispensable life skills that enhance their competencies and agency to make informed and effective decisions regarding their health and economic lives. Despite its growing traction, little is known regarding links between the CSP and its abilities to improve HIV prevention outcomes for youths. Given the paucity of research, this study aimed to explore the experiences of youths participating in the CSP and HIV prevention programme, with a particular focus on the resource-constrained settings of Gauteng Province in South Africa. This study employed a collective case study design, within the qualitative approach, and was exploratory. In-depth individual interviews were conducted with 30 youths from six established NGOs in the City of Johannesburg (CoJ). Qualitative thematic analysis was employed as a data analysis strategy. Focus groups were separately with six practitioners from the same six NGOs, and five officials from the Department of Social Development (DSD). Both phases of data collection were guided by interview themes, which were aligned with the objectives of the study. The findings of the study point to the fact that the CSP’s innovative and holistic approach offered numerous transformative and empowering benefits to youths. It equipped them with basic informational resources, capabilities, and social assets to safeguard their health and aid their economic advancement. The programme’s mixedgender sessions provided space, freedom, and support for youths to engage on issues of gender, differential access to health and socio-economic opportunities. Another major finding of the study was that improvement of economic aptitude (brought about by financial literacy education), employability, and entrepreneurship training stirred a sense of agency and purposefulness among youths, which in turn, prompted them to be more focused on achieving long-term objectives instead of indulging in risky sexual practices. Conversely, findings revealed that the programme had limited opportunities and did not create an adequate supportive environment for youths to develop successful entrepreneurial or income-generating projects. There was also no structure to assist youths to access apprenticeship and employment markets. The study specifically recognised that the programme’s efforts to develop youths’ entrepreneurship and employability capabilities were curtailed by a lack of mentorshipnand access to financial capital for start-up costs. With these findings in mind, recommendations are made for the creation of an enabling environment by purposefully engaging youths, establishing collaborative relations with communities, and building networks with businesses and financial institutions that can help youths with capital, mentorship, and linkages to internship and wage employment. Such collaborations could be fundamental in unravelling the impact of the programme on building livelihoods and reducing HIV among youths. Hence, this study proposes a model with strategies to support the successful implementation of economic strengthening interventions for youths. , Thesis (PhD) -- Faculty of Social Sciences and Humanities, 2023
- Full Text:
- Date Issued: 2023-04
- Authors: Zibengwa, Enock
- Date: 2023-04
- Subjects: HIV infections -- Prevention , HIV (Viruses) , HIV infections -- Africa
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10353/27347 , vital:66944
- Description: South Africa continues to experience unacceptably high Human Immunodeficiency Virus HIV incidence rates among youths aged 15 to 24 years. Remarkably, this is despite the numerous youth HIV prevention programmes that have been implemented in the country. Unfortunately, the programmes have not significantly curbed the spread of HIV due to the partial and fragmented nature of their implementation. The programmes are also observed to be weak in addressing complex economic factors recognised as important structural drivers for vulnerabilities that put youths at risk of HIV infection. To address this challenge, there is increased adoption and implementation of the Combination Social Protection introduced in this research as the CSP by Non-Governmental Organisations NGOs. The CSP is a youth empowerment programming strategy whose critical foundations are entrenched in combining economic strengthening interventions and HIV prevention education. CSP could provide youths with a set of indispensable life skills that enhance their competencies and agency to make informed and effective decisions regarding their health and economic lives. Despite its growing traction, little is known regarding links between the CSP and its abilities to improve HIV prevention outcomes for youths. Given the paucity of research, this study aimed to explore the experiences of youths participating in the CSP and HIV prevention programme, with a particular focus on the resource-constrained settings of Gauteng Province in South Africa. This study employed a collective case study design, within the qualitative approach, and was exploratory. In-depth individual interviews were conducted with 30 youths from six established NGOs in the City of Johannesburg (CoJ). Qualitative thematic analysis was employed as a data analysis strategy. Focus groups were separately with six practitioners from the same six NGOs, and five officials from the Department of Social Development (DSD). Both phases of data collection were guided by interview themes, which were aligned with the objectives of the study. The findings of the study point to the fact that the CSP’s innovative and holistic approach offered numerous transformative and empowering benefits to youths. It equipped them with basic informational resources, capabilities, and social assets to safeguard their health and aid their economic advancement. The programme’s mixedgender sessions provided space, freedom, and support for youths to engage on issues of gender, differential access to health and socio-economic opportunities. Another major finding of the study was that improvement of economic aptitude (brought about by financial literacy education), employability, and entrepreneurship training stirred a sense of agency and purposefulness among youths, which in turn, prompted them to be more focused on achieving long-term objectives instead of indulging in risky sexual practices. Conversely, findings revealed that the programme had limited opportunities and did not create an adequate supportive environment for youths to develop successful entrepreneurial or income-generating projects. There was also no structure to assist youths to access apprenticeship and employment markets. The study specifically recognised that the programme’s efforts to develop youths’ entrepreneurship and employability capabilities were curtailed by a lack of mentorshipnand access to financial capital for start-up costs. With these findings in mind, recommendations are made for the creation of an enabling environment by purposefully engaging youths, establishing collaborative relations with communities, and building networks with businesses and financial institutions that can help youths with capital, mentorship, and linkages to internship and wage employment. Such collaborations could be fundamental in unravelling the impact of the programme on building livelihoods and reducing HIV among youths. Hence, this study proposes a model with strategies to support the successful implementation of economic strengthening interventions for youths. , Thesis (PhD) -- Faculty of Social Sciences and Humanities, 2023
- Full Text:
- Date Issued: 2023-04
Integration of digital media and pedagogy in the twenty first century classroom: a survey of selected high schools in Eastern Cape, South Africa
- Authors: Mhlomi, Yolisa
- Date: 2023-04
- Subjects: Teaching , Digital media , Classroom learning centers
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10353/27369 , vital:66952
- Description: The essence of this thesis was to study the effectiveness of integrating digital media technologies within the pedagogical approaches adopted and implemented in private and public high schools in a comparative manner. The study looked closely at private and public high schools of the Eastern Cape Province, to study the gaps of accessibility to technology by schools. The study identified the Eastern Cape Province as having a problem of poor performance in matric results at the end of each year as compared to other South African provinces. In order to select the relevant sample for the study, the researcher has utilized two secondary schools private and public in Makhanda Grahamstown and one public secondary school in Alice. The pragmatic paradigm was used to inform the study and used the mixed methods approach to data collection. The researcher distributed closed ended questionnaires to the learners in the three selected secondary schools and semi-structured interviews for the principals of the schools. The key findings reveal that the digital media tools are used for the teaching and learning purposes as well as communication to the schools’ stakeholders. The findings also revealed that various online platforms are utilized for teaching and sharing of information. For example, D6 and Ibambisa School Communicator app, WhatsApp groups for learners, Facebook, Instagram and School website for potential stakeholders. Hence, the results of this study should contribute to the field of ICTs and education in the country to solve the problems facing the teaching and learning systems of private and public schools of the Eastern Cape. Most schools (especially the public) do not have access to digital media tools in their classrooms. Thus, they still depend heavily on the textbooks, which may be outdated or not enough for all learners. In response to the issues faced by the Eastern Cape secondary schools and the findings, the researcher has suggested a model named the Digital Media and Pedagogy Integration DMPI Model of Communication. This model will contribute to the body of knowledge by providing advice to the Department of Basic Education on how teachers and learners can utilize digital media tools effectively. Also, the study has recommended that there is a need for provision of computer literacy training for teachers in secondary schools in this digital age. , Thesis (PhD) -- Faculty of Social Sciences and Humanities, 2023
- Full Text:
- Date Issued: 2023-04
- Authors: Mhlomi, Yolisa
- Date: 2023-04
- Subjects: Teaching , Digital media , Classroom learning centers
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10353/27369 , vital:66952
- Description: The essence of this thesis was to study the effectiveness of integrating digital media technologies within the pedagogical approaches adopted and implemented in private and public high schools in a comparative manner. The study looked closely at private and public high schools of the Eastern Cape Province, to study the gaps of accessibility to technology by schools. The study identified the Eastern Cape Province as having a problem of poor performance in matric results at the end of each year as compared to other South African provinces. In order to select the relevant sample for the study, the researcher has utilized two secondary schools private and public in Makhanda Grahamstown and one public secondary school in Alice. The pragmatic paradigm was used to inform the study and used the mixed methods approach to data collection. The researcher distributed closed ended questionnaires to the learners in the three selected secondary schools and semi-structured interviews for the principals of the schools. The key findings reveal that the digital media tools are used for the teaching and learning purposes as well as communication to the schools’ stakeholders. The findings also revealed that various online platforms are utilized for teaching and sharing of information. For example, D6 and Ibambisa School Communicator app, WhatsApp groups for learners, Facebook, Instagram and School website for potential stakeholders. Hence, the results of this study should contribute to the field of ICTs and education in the country to solve the problems facing the teaching and learning systems of private and public schools of the Eastern Cape. Most schools (especially the public) do not have access to digital media tools in their classrooms. Thus, they still depend heavily on the textbooks, which may be outdated or not enough for all learners. In response to the issues faced by the Eastern Cape secondary schools and the findings, the researcher has suggested a model named the Digital Media and Pedagogy Integration DMPI Model of Communication. This model will contribute to the body of knowledge by providing advice to the Department of Basic Education on how teachers and learners can utilize digital media tools effectively. Also, the study has recommended that there is a need for provision of computer literacy training for teachers in secondary schools in this digital age. , Thesis (PhD) -- Faculty of Social Sciences and Humanities, 2023
- Full Text:
- Date Issued: 2023-04
Microstructural based creep life assessment of 1CrMov Turbine rotor steels after long-term service
- Nyembe, Hlanganani Siphelele
- Authors: Nyembe, Hlanganani Siphelele
- Date: 2023-04
- Subjects: Materials – Creep –South Africa , Steel -- Creep
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10948/61380 , vital:70622
- Description: Creep-resistant 1CrMoV steels are used for high-pressure turbine rotors in fossil fuel power stations operating at steam temperatures up to 565 °C in the creep regime. The upper bainitic microstructure of 1CrMoV rotors changes when exposed to high temperature service over long periods. The aim of this study was to relate these microstructural changes for service exposed 1CrMoV rotor steels to the remaining creep life as determined using existing methods. Analytical electron microscopy was used to quantitatively study the microstructural evolution of service-exposed 1CrMoV steel rotors. 1CrMoV rotor steel samples were characterised in the initial state, and three long-term (272 h to 300 kh) service exposed states. Detailed microstructural investigations were conducted to analyse the cavities; bainitic laths and packets; dislocations; carbide phases and their size, population, composition. The creep life fractions were estimated using conventional life assessment methods based on creep cavitation and hardness. The creep life fraction consumed of the rotors, estimated based on the creep cavities and hardness data, ranged from ~0.5 to 1. Electron backscattered diffraction (EBSD) was used to analyse the bainitic packets, laths, misorientations, and dislocations, which showed that the bainitic lath surface area to volume (SV) correlated with service time. The precipitates were extracted from the Fe-matrix using extraction replication and were further investigated using transmission Kikuchi diffraction (TKD), scanning transmission electron microscopy (STEM), selected area electron diffraction (SAED), and energy dispersive spectroscopy (EDS). STEM-EDS and TKD identified M3C, MC, M2C, M7C3, and M23C6 (M = Fe, Cr, Mo, V, Mn) in the 1CrMoV steels. STEM-EDS measurements revealed that Fe/Cr ratios in M3C decreased from 4.5 (initial state) to 2.5 (>272 kh). The Fe/Cr and Fe/Mo ratios in overall carbides decreased from 5 and 10 (initial state) to 1 and 2 (>272 kh), respectively. The TKD analysis indicated that the relative phase proportion of M2C and M7C3 carbides, relative to the total extracted carbides, is positively correlated with service exposure. These microstructural features correlate with the creep life fraction consumed and could potentially be used as another indicator of the remnant creep life. , Thesis (PhD) -- Faculty of Science, School of Computer Science, Mathematics, Physics and Statistics. 2023
- Full Text:
- Date Issued: 2023-04
- Authors: Nyembe, Hlanganani Siphelele
- Date: 2023-04
- Subjects: Materials – Creep –South Africa , Steel -- Creep
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10948/61380 , vital:70622
- Description: Creep-resistant 1CrMoV steels are used for high-pressure turbine rotors in fossil fuel power stations operating at steam temperatures up to 565 °C in the creep regime. The upper bainitic microstructure of 1CrMoV rotors changes when exposed to high temperature service over long periods. The aim of this study was to relate these microstructural changes for service exposed 1CrMoV rotor steels to the remaining creep life as determined using existing methods. Analytical electron microscopy was used to quantitatively study the microstructural evolution of service-exposed 1CrMoV steel rotors. 1CrMoV rotor steel samples were characterised in the initial state, and three long-term (272 h to 300 kh) service exposed states. Detailed microstructural investigations were conducted to analyse the cavities; bainitic laths and packets; dislocations; carbide phases and their size, population, composition. The creep life fractions were estimated using conventional life assessment methods based on creep cavitation and hardness. The creep life fraction consumed of the rotors, estimated based on the creep cavities and hardness data, ranged from ~0.5 to 1. Electron backscattered diffraction (EBSD) was used to analyse the bainitic packets, laths, misorientations, and dislocations, which showed that the bainitic lath surface area to volume (SV) correlated with service time. The precipitates were extracted from the Fe-matrix using extraction replication and were further investigated using transmission Kikuchi diffraction (TKD), scanning transmission electron microscopy (STEM), selected area electron diffraction (SAED), and energy dispersive spectroscopy (EDS). STEM-EDS and TKD identified M3C, MC, M2C, M7C3, and M23C6 (M = Fe, Cr, Mo, V, Mn) in the 1CrMoV steels. STEM-EDS measurements revealed that Fe/Cr ratios in M3C decreased from 4.5 (initial state) to 2.5 (>272 kh). The Fe/Cr and Fe/Mo ratios in overall carbides decreased from 5 and 10 (initial state) to 1 and 2 (>272 kh), respectively. The TKD analysis indicated that the relative phase proportion of M2C and M7C3 carbides, relative to the total extracted carbides, is positively correlated with service exposure. These microstructural features correlate with the creep life fraction consumed and could potentially be used as another indicator of the remnant creep life. , Thesis (PhD) -- Faculty of Science, School of Computer Science, Mathematics, Physics and Statistics. 2023
- Full Text:
- Date Issued: 2023-04
The effect of Cannabis extract on the morphological and metabolic characteristics of various fat depots in diet-induced Obese and STZ-induced male wistar rats
- Authors: Ramlugon, Sonaal
- Date: 2023-04
- Subjects: Rats as laboratory animals , Diabetes in practice , Cannabis -- South Africa
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10948/61282 , vital:70044
- Description: To investigate the potential anti-diabetic/obesity properties of oral cannabis administration in an obese and streptozotocin (STZ)-induced diabetic rat model, as well as an obese rat model, and to determine the mechanism of action, with a focus on the peritoneal and intramuscular fat depots. Experimental Design: Obese and STZ-induced diabetic rats were allocated a high fat diet (HFD) and intraperitoneally injected with STZ to mimic an obese and diabetic state. The rats were then orally administered cannabis extract (CE) of 1.25, 2.5 and 5.0 mg/kg body weight (relative to tetrahydrocannabinol (THC) content) or metformin as a positive control. For the obese rat model, the rats were allocated either a high carbohydrate diet (HCD) or high fat diet (HFD) and orally administered with cannabis extract of 1.25 mg/kg body weight (relative to THC content). Weight, blood and insulin-resistant parameters of the rats were monitored. The mitochondrial to genomic DNA ratio (MT:18S DNA), average adipocyte area of the various adipose tissues, citrate synthase and carnitine palmitoyltransferase 1 (CPT1) enzyme activities of the peritoneal and intramuscular fat were measured. Gene expression levels of uncoupling protein 1 (UCP1), cell-death inducing DNA fragmentation factor alpha like effector-a (Cidea), perilipin, hormone-sensitive lipase (HSL) and mitochondrial transcription factor A (TFAM) were measured in peritoneal fat, intramuscular fat and brown adipose tissue (BAT). Main Findings: Obese and STZ-induced diabetic rat model: Due to the biphasic nature of cannabinoids, cannabis dosage plays an important role in the observed effects. CE1.25 was the only cannabis treatment effective in improving the insulinresistant parameters of the rats unlike the other higher cannabis concentrations (CE2.5 and CE5.0). In the peritoneal fat, CE1.25 increased MT:18S DNA, increased citrate synthase activity, and decreased the average adipocyte area when compared to the STZ group. CE1.25 also induced fat beigeing by upregulating gene expression levels of UCP1 and Cidea. XIX Furthermore, an increase in gene expression levels of perilipin, HSL, and TFAM showed increased fat mobilization and metabolic activity. In the intramuscular fat, CE1.25 also reduced the average adipocytes area. However, a different mechanism of action was observed where CE1.25 did not induce fat beigeing, but instead increased both citrate synthase and CPT1 enzyme activities and gene expression levels of HSL, thereby indicating increased fat oxidation and mitochondrial activity. , Thesis (PhD) -- Faculty of Science, School of Biomolecular and Chemical Sciences, 2023
- Full Text:
- Date Issued: 2023-04
- Authors: Ramlugon, Sonaal
- Date: 2023-04
- Subjects: Rats as laboratory animals , Diabetes in practice , Cannabis -- South Africa
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10948/61282 , vital:70044
- Description: To investigate the potential anti-diabetic/obesity properties of oral cannabis administration in an obese and streptozotocin (STZ)-induced diabetic rat model, as well as an obese rat model, and to determine the mechanism of action, with a focus on the peritoneal and intramuscular fat depots. Experimental Design: Obese and STZ-induced diabetic rats were allocated a high fat diet (HFD) and intraperitoneally injected with STZ to mimic an obese and diabetic state. The rats were then orally administered cannabis extract (CE) of 1.25, 2.5 and 5.0 mg/kg body weight (relative to tetrahydrocannabinol (THC) content) or metformin as a positive control. For the obese rat model, the rats were allocated either a high carbohydrate diet (HCD) or high fat diet (HFD) and orally administered with cannabis extract of 1.25 mg/kg body weight (relative to THC content). Weight, blood and insulin-resistant parameters of the rats were monitored. The mitochondrial to genomic DNA ratio (MT:18S DNA), average adipocyte area of the various adipose tissues, citrate synthase and carnitine palmitoyltransferase 1 (CPT1) enzyme activities of the peritoneal and intramuscular fat were measured. Gene expression levels of uncoupling protein 1 (UCP1), cell-death inducing DNA fragmentation factor alpha like effector-a (Cidea), perilipin, hormone-sensitive lipase (HSL) and mitochondrial transcription factor A (TFAM) were measured in peritoneal fat, intramuscular fat and brown adipose tissue (BAT). Main Findings: Obese and STZ-induced diabetic rat model: Due to the biphasic nature of cannabinoids, cannabis dosage plays an important role in the observed effects. CE1.25 was the only cannabis treatment effective in improving the insulinresistant parameters of the rats unlike the other higher cannabis concentrations (CE2.5 and CE5.0). In the peritoneal fat, CE1.25 increased MT:18S DNA, increased citrate synthase activity, and decreased the average adipocyte area when compared to the STZ group. CE1.25 also induced fat beigeing by upregulating gene expression levels of UCP1 and Cidea. XIX Furthermore, an increase in gene expression levels of perilipin, HSL, and TFAM showed increased fat mobilization and metabolic activity. In the intramuscular fat, CE1.25 also reduced the average adipocytes area. However, a different mechanism of action was observed where CE1.25 did not induce fat beigeing, but instead increased both citrate synthase and CPT1 enzyme activities and gene expression levels of HSL, thereby indicating increased fat oxidation and mitochondrial activity. , Thesis (PhD) -- Faculty of Science, School of Biomolecular and Chemical Sciences, 2023
- Full Text:
- Date Issued: 2023-04
Unleashing the nexus between climate change and food security in rural South Africa: role of three community radio stations in the Eastern Cape Province
- Authors: Bamigboye, Foluke Bosede
- Date: 2023-04
- Subjects: Climatic changes , Food security , South Africa -- Rural conditions
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10353/27325 , vital:66939
- Description: This study investigates the role of Forte FM, Mdantsane FM and Rhodes Music Community Radios in disseminating the different kinds of messages on the nexus between the impacts of climate change and food security in the Eastern Cape Province, South Africa. Therefore, the study aims to investigate how these community radio stations play their informative, educative and entertainment roles regarding climate change and food security awareness programmes to their listeners. The study employed the qualitative research approach and convenience, and non-probability samplings techniques were subsequently used to select samples for this study. In-depth interviews were conducted individually for Forte FM, Mdantsane FM and Rhodes Music community radio programme managers respectively, who serve as the key informants. One focus group discussion each was held with residents of Golf Course, Mdantsane and Grahamstown areas where these radio stations broadcast from, with eight participants in each focus group. The total number of participants for the focus group discussions was 24 participants. The collected data were coded into themes using NVivo 12 software to generate the theme nodes and case nodes as key findings, analysis and then interpreted. The findings of this study confirmed that these three community radio stations do contribute to climate change communication through their programmes that focus on climate change and food security related issues. Another vital finding from the study showed that listeners do benefit immensely from these climate change and food security related programmes of the under-study community radio stations. Hence, listeners physical, social, and cognitive well-being of their climatic environment have been greatly impacted. In the same vein, the findings of this study further revealed that the rural communities who are mostly affected by the impacts of climate change on food security have been well informed and enlightened on the suitable ways to enhance a sustainable food security and climate adaptation system through Forte FM, Mdantsane FM, and Rhodes Music community radio stations. Significantly, this study has been able to come up with two suggested models and the conceptual frameworks, which are the Local Action Adaptive Communication (LAAC) Model and the Indigenous Behavioral Change Conceptual (IBCC) Model. These models are focused on increasing listeners interests, adaptation, and behavioral change on climate change issues. The models are also aimed at ensuring better climate change and food security communication Author. , Thesis (PhD) -- Faculty of Social Sciences and Humanities, 2023
- Full Text:
- Date Issued: 2023-04
- Authors: Bamigboye, Foluke Bosede
- Date: 2023-04
- Subjects: Climatic changes , Food security , South Africa -- Rural conditions
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10353/27325 , vital:66939
- Description: This study investigates the role of Forte FM, Mdantsane FM and Rhodes Music Community Radios in disseminating the different kinds of messages on the nexus between the impacts of climate change and food security in the Eastern Cape Province, South Africa. Therefore, the study aims to investigate how these community radio stations play their informative, educative and entertainment roles regarding climate change and food security awareness programmes to their listeners. The study employed the qualitative research approach and convenience, and non-probability samplings techniques were subsequently used to select samples for this study. In-depth interviews were conducted individually for Forte FM, Mdantsane FM and Rhodes Music community radio programme managers respectively, who serve as the key informants. One focus group discussion each was held with residents of Golf Course, Mdantsane and Grahamstown areas where these radio stations broadcast from, with eight participants in each focus group. The total number of participants for the focus group discussions was 24 participants. The collected data were coded into themes using NVivo 12 software to generate the theme nodes and case nodes as key findings, analysis and then interpreted. The findings of this study confirmed that these three community radio stations do contribute to climate change communication through their programmes that focus on climate change and food security related issues. Another vital finding from the study showed that listeners do benefit immensely from these climate change and food security related programmes of the under-study community radio stations. Hence, listeners physical, social, and cognitive well-being of their climatic environment have been greatly impacted. In the same vein, the findings of this study further revealed that the rural communities who are mostly affected by the impacts of climate change on food security have been well informed and enlightened on the suitable ways to enhance a sustainable food security and climate adaptation system through Forte FM, Mdantsane FM, and Rhodes Music community radio stations. Significantly, this study has been able to come up with two suggested models and the conceptual frameworks, which are the Local Action Adaptive Communication (LAAC) Model and the Indigenous Behavioral Change Conceptual (IBCC) Model. These models are focused on increasing listeners interests, adaptation, and behavioral change on climate change issues. The models are also aimed at ensuring better climate change and food security communication Author. , Thesis (PhD) -- Faculty of Social Sciences and Humanities, 2023
- Full Text:
- Date Issued: 2023-04
Use of flow reactors for an improved synthesis of Tenofovir derivatives
- Authors: Sonti, Thembela
- Date: 2023-04
- Subjects: Antiviral agents -- South Africa , HIV infections –Treatment
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10948/61190 , vital:69792
- Description: Tenofovir disoproxil fumarate (TDF) is a prescription drug used to treat and prevent human immunodeficiency virus (HIV) infections. It aids in the reduction of HIV in the body, allowing the immune system to function more effectively. This reduces the risk of HIV complications, such as infections, whilst improving the quality of life. TDF belongs to the nucleotide reverse transcriptase inhibitors category of drugs. These drugs limit the ability of the reverse transcriptase, an enzyme essential for each virus to replicate itself. A reduction in the cost of HIV treatment could improve supply security and make it more accessible to patients in need. Thus, this project aims to use flow technology to achieve a guaranteed supply chain and access. In this thesis, a method for the synthesis of TDF was developed using microreactors starting from the readily available adenine. The method was adapted from the traditional batch synthesis as currently there is no literature on the synthesis of TDF in flow chemistry. The batch methods used for the synthesis of the working standards were successfully translated to flow systems. For the best results to be obtained, optimisation of the reaction temperature, reagent molar equivalents and concentration was critical. From the optimisation studies, an improvement in conversion is evident throughout all stages. The flow synthesis of the first intermediate resulted in a conversion of 100 % in N,N-dimethylformamide in 6 min residence time. This study was conducted at 200 °C, which is higher than the boiling point of the solvent with the aid of a back pressure regulator. A key reagent in the synthesis of tenofovir, namely ((tosyloxy)methyl)phosphonic acid, had to be synthesised and it was successfully produced in 96 % yield. The second intermediate was synthesised through a successful coupling reaction between (R)-9-(2-hydroxypropyl)adenine and ((tosyloxy)methyl)- phosphonic acid, which afforded a 100 % conversion of tenofovir in 20 min total residence time. The multistep synthesis of tenofovir was a success as it afforded a 65 % overall conversion. The prodrug TDF was successfully synthesised at 120 °C with a 30 min residence time, yielding a conversion of 100 %. ii | P a g e This thesis consists of four chapters. Chapter one describes the background on HIV and a literature review on HIV drugs. This chapter also demonstrates flow chemistry and microreactors in detail and different routes for the synthesis of TDF in traditional batch methods. Chapter two provides a detailed methodology for batch synthesis and flow synthesis with analytical data. 1H-NMR, 13C-NMR and FTIR spectroscopy was used to evaluate all the compounds synthesised in this chapter. Chapter three thoroughly discusses the results that were obtained graphically, showing that the flow synthesis gives better yields than batch synthesis. In chapter 4, the conclusion of the whole investigation is stated along with the future work for the preparation of TDF. , Thesis (PhD) -- Faculty of Science, School of Biomolecular and Chemical Sciences, 2023
- Full Text:
- Date Issued: 2023-04
- Authors: Sonti, Thembela
- Date: 2023-04
- Subjects: Antiviral agents -- South Africa , HIV infections –Treatment
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10948/61190 , vital:69792
- Description: Tenofovir disoproxil fumarate (TDF) is a prescription drug used to treat and prevent human immunodeficiency virus (HIV) infections. It aids in the reduction of HIV in the body, allowing the immune system to function more effectively. This reduces the risk of HIV complications, such as infections, whilst improving the quality of life. TDF belongs to the nucleotide reverse transcriptase inhibitors category of drugs. These drugs limit the ability of the reverse transcriptase, an enzyme essential for each virus to replicate itself. A reduction in the cost of HIV treatment could improve supply security and make it more accessible to patients in need. Thus, this project aims to use flow technology to achieve a guaranteed supply chain and access. In this thesis, a method for the synthesis of TDF was developed using microreactors starting from the readily available adenine. The method was adapted from the traditional batch synthesis as currently there is no literature on the synthesis of TDF in flow chemistry. The batch methods used for the synthesis of the working standards were successfully translated to flow systems. For the best results to be obtained, optimisation of the reaction temperature, reagent molar equivalents and concentration was critical. From the optimisation studies, an improvement in conversion is evident throughout all stages. The flow synthesis of the first intermediate resulted in a conversion of 100 % in N,N-dimethylformamide in 6 min residence time. This study was conducted at 200 °C, which is higher than the boiling point of the solvent with the aid of a back pressure regulator. A key reagent in the synthesis of tenofovir, namely ((tosyloxy)methyl)phosphonic acid, had to be synthesised and it was successfully produced in 96 % yield. The second intermediate was synthesised through a successful coupling reaction between (R)-9-(2-hydroxypropyl)adenine and ((tosyloxy)methyl)- phosphonic acid, which afforded a 100 % conversion of tenofovir in 20 min total residence time. The multistep synthesis of tenofovir was a success as it afforded a 65 % overall conversion. The prodrug TDF was successfully synthesised at 120 °C with a 30 min residence time, yielding a conversion of 100 %. ii | P a g e This thesis consists of four chapters. Chapter one describes the background on HIV and a literature review on HIV drugs. This chapter also demonstrates flow chemistry and microreactors in detail and different routes for the synthesis of TDF in traditional batch methods. Chapter two provides a detailed methodology for batch synthesis and flow synthesis with analytical data. 1H-NMR, 13C-NMR and FTIR spectroscopy was used to evaluate all the compounds synthesised in this chapter. Chapter three thoroughly discusses the results that were obtained graphically, showing that the flow synthesis gives better yields than batch synthesis. In chapter 4, the conclusion of the whole investigation is stated along with the future work for the preparation of TDF. , Thesis (PhD) -- Faculty of Science, School of Biomolecular and Chemical Sciences, 2023
- Full Text:
- Date Issued: 2023-04
Viability of government funded broiler production : lessons from Northern KwaZulu Natal, South Africa
- Mdletshe, Sifiso Themba Clement https://orcid.org/0000-0002-2668-0193
- Authors: Mdletshe, Sifiso Themba Clement https://orcid.org/0000-0002-2668-0193
- Date: 2023-04
- Subjects: Broilers (Chickens) -- Economic aspects , Broilers (Poultry) , Broilers (Chickens) -- Breeding
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10353/27843 , vital:69947
- Description: Generally, rural areas continue to experience high poverty levels and low incomes, which seem to be occasioned by high unemployment rates, limited educational attainments, and devastating floods and droughts. This situation is further exacerbated by increase in crime rates, making livelihoods even more difficult. To mitigate such adverse situations, rural households employ diverse strategies, including maintaining community gardens, one-home-one-garden schemes, as well as livestock and poultry production. The most prevalent livelihood strategy in South Africa or KwaZulu-Natal is broiler production, since it needs less space and a short production cycle compared to other livestock or crop enterprises. At the same time, income is generated over a short period. Besides, the government of KwaZulu Natal has actively intervened in the sector as part of its broader poverty reduction strategy and farmer support programmes. In KwaZulu-Natal Province, the provincial government has been supporting broiler producers for many years. While substantial research work has been done in the province on livelihood strategies, including livestock production on a province-wide basis, there is no information about how successful the broiler production funded by the government has being. Broader concerns about production problems have not been assuaged based on systematic studies and evidence. It is this wise that this study was initiated. The objective is to assess the economic viability of government-funded small-scale broiler projects in the KwaZulu-Natal Province of South Africa and determine the implications for poverty reduction and food security. Data were collected from the government-funded small-scale broiler producers that are residing in Northern KwaZulu-Natal districts uThungulu, Zululand and uMkhanyakude. A total of 75 small-scale broiler projects 25 broiler projects in each district were selected by probability sampling procedure for the interviews. Questionnaires that combined both close-ended and open-ended questions were used to collect primary data, which include production and marketing, as well as the factors that influence the profitability of the small-scale broiler projects. After collection, data were captured and encoded on spreadsheets in Microsoft Excel and exported to Statistical Package for the Social Science (SPSS) software version 26 and STATA for analyses. Descriptive statistics applied include frequencies and means. In addition, a gross margin (GM) and gross profit margin (GPM) analysis were employed to assess the profitability of government-funded small-scale broiler projects. Both profitability and gross margin analyses were used as proxies for farmers’ motivation and incentives to participate in broiler production. Further analyses were conducted to determine the model that best explains the underlying relationships. Initially, the Multiple Linear Regression Model was applied to determine the factors influencing the profitability of government-funded small-scale broiler projects. The indication was that while positive profits were revealed, the system seemed to fall short of its potential. In light of that, it was decided to fit another model to estimate the technical efficiency of the system and gain an understanding of the causes of any inefficiency that might exist in the production system. In that regard, the one-step Stochastic Frontier Model was employed to show that the technical efficiency of broiler production systems in the project area was positively and significantly influenced by flock size, the quantity of feeds and labour costs, while medication played no role possibly because of weak extension coverage. An inefficiency model fitted as part of the one-step model suggested that age, gender and educational level were significant influencers of technical inefficiency, with the possibility that the older the farmers, the more technically inefficient the system possibly because of the strenuousness of commercial poultry production. In addition, it was found that the more educated the farmer, the less inefficient the farm, which conversely means that the system becomes more efficient as the farmer receives more education. The negative coefficient of the gender variable also implies that for farms managed by female farmers, the system was less inefficient, which is more technically efficient, and this can be explained by women’s propensity to be more gentle, caring and sensitive in managing the chickens than their male counterparts. Heteroskedasticity tests and corrections were conducted in the one-step estimation technique to show that variations in the inefficiency term (μ) and the stochastic error term were explained by age and educational level for the most part. Clearly, improvements in the broiler industry in KwaZulu-Natal will depend to a large extent on the knowledge and experience of the farmers and substantial enlargement of the flock size of adequately fed birds. Attention to these elements is expected to have important practical implications for sustainable broiler poultry development and food security in the project area, as well as locations possessing identical features and characteristics. , Thesis (MSci) -- Faculty of Science and Agriculture, 2023
- Full Text:
- Date Issued: 2023-04
- Authors: Mdletshe, Sifiso Themba Clement https://orcid.org/0000-0002-2668-0193
- Date: 2023-04
- Subjects: Broilers (Chickens) -- Economic aspects , Broilers (Poultry) , Broilers (Chickens) -- Breeding
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10353/27843 , vital:69947
- Description: Generally, rural areas continue to experience high poverty levels and low incomes, which seem to be occasioned by high unemployment rates, limited educational attainments, and devastating floods and droughts. This situation is further exacerbated by increase in crime rates, making livelihoods even more difficult. To mitigate such adverse situations, rural households employ diverse strategies, including maintaining community gardens, one-home-one-garden schemes, as well as livestock and poultry production. The most prevalent livelihood strategy in South Africa or KwaZulu-Natal is broiler production, since it needs less space and a short production cycle compared to other livestock or crop enterprises. At the same time, income is generated over a short period. Besides, the government of KwaZulu Natal has actively intervened in the sector as part of its broader poverty reduction strategy and farmer support programmes. In KwaZulu-Natal Province, the provincial government has been supporting broiler producers for many years. While substantial research work has been done in the province on livelihood strategies, including livestock production on a province-wide basis, there is no information about how successful the broiler production funded by the government has being. Broader concerns about production problems have not been assuaged based on systematic studies and evidence. It is this wise that this study was initiated. The objective is to assess the economic viability of government-funded small-scale broiler projects in the KwaZulu-Natal Province of South Africa and determine the implications for poverty reduction and food security. Data were collected from the government-funded small-scale broiler producers that are residing in Northern KwaZulu-Natal districts uThungulu, Zululand and uMkhanyakude. A total of 75 small-scale broiler projects 25 broiler projects in each district were selected by probability sampling procedure for the interviews. Questionnaires that combined both close-ended and open-ended questions were used to collect primary data, which include production and marketing, as well as the factors that influence the profitability of the small-scale broiler projects. After collection, data were captured and encoded on spreadsheets in Microsoft Excel and exported to Statistical Package for the Social Science (SPSS) software version 26 and STATA for analyses. Descriptive statistics applied include frequencies and means. In addition, a gross margin (GM) and gross profit margin (GPM) analysis were employed to assess the profitability of government-funded small-scale broiler projects. Both profitability and gross margin analyses were used as proxies for farmers’ motivation and incentives to participate in broiler production. Further analyses were conducted to determine the model that best explains the underlying relationships. Initially, the Multiple Linear Regression Model was applied to determine the factors influencing the profitability of government-funded small-scale broiler projects. The indication was that while positive profits were revealed, the system seemed to fall short of its potential. In light of that, it was decided to fit another model to estimate the technical efficiency of the system and gain an understanding of the causes of any inefficiency that might exist in the production system. In that regard, the one-step Stochastic Frontier Model was employed to show that the technical efficiency of broiler production systems in the project area was positively and significantly influenced by flock size, the quantity of feeds and labour costs, while medication played no role possibly because of weak extension coverage. An inefficiency model fitted as part of the one-step model suggested that age, gender and educational level were significant influencers of technical inefficiency, with the possibility that the older the farmers, the more technically inefficient the system possibly because of the strenuousness of commercial poultry production. In addition, it was found that the more educated the farmer, the less inefficient the farm, which conversely means that the system becomes more efficient as the farmer receives more education. The negative coefficient of the gender variable also implies that for farms managed by female farmers, the system was less inefficient, which is more technically efficient, and this can be explained by women’s propensity to be more gentle, caring and sensitive in managing the chickens than their male counterparts. Heteroskedasticity tests and corrections were conducted in the one-step estimation technique to show that variations in the inefficiency term (μ) and the stochastic error term were explained by age and educational level for the most part. Clearly, improvements in the broiler industry in KwaZulu-Natal will depend to a large extent on the knowledge and experience of the farmers and substantial enlargement of the flock size of adequately fed birds. Attention to these elements is expected to have important practical implications for sustainable broiler poultry development and food security in the project area, as well as locations possessing identical features and characteristics. , Thesis (MSci) -- Faculty of Science and Agriculture, 2023
- Full Text:
- Date Issued: 2023-04
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