Carbonylation of cyclohexene with carbon dioxide (CO2) using transition metals as heterogeneous and homogeneous catalysts
- Authors: Sekaleli, Bafokeng Thabelo
- Date: 2024-10-11
- Subjects: Uncatalogued
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/464565 , vital:76522
- Description: From a green chemistry perspective, carbon dioxide (CO2) emerges as an appealing C1 synthon, given its abundance in the atmosphere and cost-effectiveness. Many essential chemicals for daily life are derived from fossilized carbon sources like coal, petroleum, and natural gas. However, the by-product of these processes, CO2, poses environmental risks when excessively emitted as a greenhouse gas. Achieving a balance between carbon emissions and removal is crucial to address environmental concerns surrounding CO2. Utilizing CO2 as a C1 source in organic synthesis holds promise for mitigating this balance in the long term. Combining CO2 with other underutilized fine chemicals, such as alkanes, alkenes, and alkynes, to produce more valuable platform chemicals presents an economically viable strategy due to carbon dioxide’s abundance, low cost, and recyclability. Despite its simplicity, CO2's high thermodynamic stability and low kinetic reactivity, owing to its highly oxidized state, pose challenges to its use as a feedstock. Overcoming these hurdles requires catalysts to enhance CO2 reactivity. Our work focuses on developing and employing catalytic systems capable of activating CO2 as a C1 synthon in reactions with cyclohexene and a reducing agent to yield carboxylic acids or esters. In one approach, we have developed heterogeneous catalyst systems comprising transition metals (Au, Fe, Ni, Ru) supported on metal oxide (TiO2). Characterization techniques such as TEM, EDX, UV-Vis, BET, and XRD were used to study the properties of these materials. The catalysts were evaluated in a reaction involving cyclohexene, CO2, and H2O. In another approach, we explored the use of cyclo-tris(tetracarbonylruthenium) [Ru3(CO)12] as a homogeneous catalyst in a reaction involving cyclohexene, methanol, and CO2 in the presence of an ionic liquid, 1-Butyl-3-methylimidazolium chloride ([BMIM]+Cl-). 1H NMR and ATR-FT-IR were utilized to characterize [BMIM]+Cl-. The reaction product was characterised utilizing GC-MS. Upon seeing that Ru3(CO)12 changes color from orange to black when exposed to heat, an investigation was undertaken on the kind of transformations that the catalyst undergoes. This investigation was carried out with the hopes of finding the structures that could be resulting from Ru3(CO)12 during the reaction and their significance to it. The orange and black Ru complexes were characterized utilizing DSC, TGA, ATR-FT-IR and PXRD. , Thesis (MSc) -- Faculty of Science, Chemistry, 2024
- Full Text:
- Date Issued: 2024-10-11
- Authors: Sekaleli, Bafokeng Thabelo
- Date: 2024-10-11
- Subjects: Uncatalogued
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/464565 , vital:76522
- Description: From a green chemistry perspective, carbon dioxide (CO2) emerges as an appealing C1 synthon, given its abundance in the atmosphere and cost-effectiveness. Many essential chemicals for daily life are derived from fossilized carbon sources like coal, petroleum, and natural gas. However, the by-product of these processes, CO2, poses environmental risks when excessively emitted as a greenhouse gas. Achieving a balance between carbon emissions and removal is crucial to address environmental concerns surrounding CO2. Utilizing CO2 as a C1 source in organic synthesis holds promise for mitigating this balance in the long term. Combining CO2 with other underutilized fine chemicals, such as alkanes, alkenes, and alkynes, to produce more valuable platform chemicals presents an economically viable strategy due to carbon dioxide’s abundance, low cost, and recyclability. Despite its simplicity, CO2's high thermodynamic stability and low kinetic reactivity, owing to its highly oxidized state, pose challenges to its use as a feedstock. Overcoming these hurdles requires catalysts to enhance CO2 reactivity. Our work focuses on developing and employing catalytic systems capable of activating CO2 as a C1 synthon in reactions with cyclohexene and a reducing agent to yield carboxylic acids or esters. In one approach, we have developed heterogeneous catalyst systems comprising transition metals (Au, Fe, Ni, Ru) supported on metal oxide (TiO2). Characterization techniques such as TEM, EDX, UV-Vis, BET, and XRD were used to study the properties of these materials. The catalysts were evaluated in a reaction involving cyclohexene, CO2, and H2O. In another approach, we explored the use of cyclo-tris(tetracarbonylruthenium) [Ru3(CO)12] as a homogeneous catalyst in a reaction involving cyclohexene, methanol, and CO2 in the presence of an ionic liquid, 1-Butyl-3-methylimidazolium chloride ([BMIM]+Cl-). 1H NMR and ATR-FT-IR were utilized to characterize [BMIM]+Cl-. The reaction product was characterised utilizing GC-MS. Upon seeing that Ru3(CO)12 changes color from orange to black when exposed to heat, an investigation was undertaken on the kind of transformations that the catalyst undergoes. This investigation was carried out with the hopes of finding the structures that could be resulting from Ru3(CO)12 during the reaction and their significance to it. The orange and black Ru complexes were characterized utilizing DSC, TGA, ATR-FT-IR and PXRD. , Thesis (MSc) -- Faculty of Science, Chemistry, 2024
- Full Text:
- Date Issued: 2024-10-11
Carnivory submerged: aspects of the ecology and ecophysiology of the aquatic Utricularia stellaris L. fil. (Lentibulariaceae) in South Africa
- Authors: Marais, Alice-Jane
- Date: 2024-10-11
- Subjects: Uncatalogued
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/464473 , vital:76514
- Description: The trapping structures produced by aquatic species of Utricularia have traditionally been interpreted to function as adaptations to capture and break down zooplankton prey, as in other carnivorous plants, to overcome nutrient limitations. However, an increasing number of studies have found that these plants may also rely on benefits derived from living mutualistic microbial communities contained within traps. This study documents aspects of the environmental, growth and physiological characteristics of U. stellaris to inform and to form a basis for future investigation into the plant-microbe interaction. The environmental conditions in which U. stellaris grows were documented to identify potential adverse conditions plants are subject to in situ, from which nutrient limitation was identified as a primary limitation. Plant growth and trapping structures were then assessed to identify possible adaptations of plants to overcome these limitations. The production of trapping structures likely constitutes an adaptive trait, with 30% of total biomass per node allocated to the production of these structures. Based on their capture function, traps may aid plants based on their contents, possibly supplementing plants with nutrients. Although assessments of the habitats of U. stellaris indicate that dissolved CO₂ concentrations in the ambient water are high, CO₂ may still be limiting to the photosynthetic rates of these plants due to viscous water resisting the diffusion of CO₂. The primary site of photosynthesis in U. stellaris is leaves and trap tissue’s contribution to photosynthetic output is negligible. U. stellaris plants are subject to CO₂ limitations in natural pond conditions, making the substantial allocation of resources to non-photosynthetic trapping tissue even more costly. Therefore, benefits gained from trapping structures are likely to be derived from trap contents; having ruled out the possibility that the trap tissue itself is photosynthetic. Trap contents of U. stellaris were assessed. The proportion of traps containing living microbial communities greatly exceeded the proportion containing zooplankton prey. In addition, these communities were found to be diverse, stable, and self-sustaining. These results suggest that trapping structures may be beneficial for both the carnivorous capture of prey and the housing of living microbial communities. These results indicate the plantmicrobe interaction in U. stellaris warrants further study. , Thesis (MSc) -- Faculty of Science, Botany, 2024
- Full Text:
- Date Issued: 2024-10-11
- Authors: Marais, Alice-Jane
- Date: 2024-10-11
- Subjects: Uncatalogued
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/464473 , vital:76514
- Description: The trapping structures produced by aquatic species of Utricularia have traditionally been interpreted to function as adaptations to capture and break down zooplankton prey, as in other carnivorous plants, to overcome nutrient limitations. However, an increasing number of studies have found that these plants may also rely on benefits derived from living mutualistic microbial communities contained within traps. This study documents aspects of the environmental, growth and physiological characteristics of U. stellaris to inform and to form a basis for future investigation into the plant-microbe interaction. The environmental conditions in which U. stellaris grows were documented to identify potential adverse conditions plants are subject to in situ, from which nutrient limitation was identified as a primary limitation. Plant growth and trapping structures were then assessed to identify possible adaptations of plants to overcome these limitations. The production of trapping structures likely constitutes an adaptive trait, with 30% of total biomass per node allocated to the production of these structures. Based on their capture function, traps may aid plants based on their contents, possibly supplementing plants with nutrients. Although assessments of the habitats of U. stellaris indicate that dissolved CO₂ concentrations in the ambient water are high, CO₂ may still be limiting to the photosynthetic rates of these plants due to viscous water resisting the diffusion of CO₂. The primary site of photosynthesis in U. stellaris is leaves and trap tissue’s contribution to photosynthetic output is negligible. U. stellaris plants are subject to CO₂ limitations in natural pond conditions, making the substantial allocation of resources to non-photosynthetic trapping tissue even more costly. Therefore, benefits gained from trapping structures are likely to be derived from trap contents; having ruled out the possibility that the trap tissue itself is photosynthetic. Trap contents of U. stellaris were assessed. The proportion of traps containing living microbial communities greatly exceeded the proportion containing zooplankton prey. In addition, these communities were found to be diverse, stable, and self-sustaining. These results suggest that trapping structures may be beneficial for both the carnivorous capture of prey and the housing of living microbial communities. These results indicate the plantmicrobe interaction in U. stellaris warrants further study. , Thesis (MSc) -- Faculty of Science, Botany, 2024
- Full Text:
- Date Issued: 2024-10-11
Characterisation, and remote sensing exploration potential, of a hydrothermally mineralised Diorite, Chris Hani district, Eastern Cape, South Africa
- Authors: Johnstone, Shawn Douglas
- Date: 2024-10-11
- Subjects: Uncatalogued
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/464930 , vital:76558
- Description: Access restricted. Expected release in 2026. , Thesis (MSc) -- Faculty of Science, Geology, 2024
- Full Text:
- Date Issued: 2024-10-11
- Authors: Johnstone, Shawn Douglas
- Date: 2024-10-11
- Subjects: Uncatalogued
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/464930 , vital:76558
- Description: Access restricted. Expected release in 2026. , Thesis (MSc) -- Faculty of Science, Geology, 2024
- Full Text:
- Date Issued: 2024-10-11
Co-crystal formation of pharmaceutical and veterinary tranquilizer molecules
- Mngwengwe, Bongeka Naledi Precious
- Authors: Mngwengwe, Bongeka Naledi Precious
- Date: 2024-10-11
- Subjects: Uncatalogued
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/464532 , vital:76519
- Description: Midazolam, a 1,4-benzodiazepine derivative is commonly used to treat anxiety, insomnia and may be used as a sedative in anaesthesia as it has calming, anti-convulsant and muscle relaxant properties. Midazolam has a rapid onset but a short duration of action resulting in fewer adverse effects. Midazolam also has the potential to form insoluble crystalline precipitates in pharmaceutical dosage forms such as syrups and solutions, which is a challenge in formulation and process development activities. The primary goal of this research was to prepare multicomponent crystals of midazolam free base, specifically targeting interactions with coformers structurally similar to methyl paraben. Key preparation techniques included neat grinding, liquid-assisted grinding, and slow evaporation. The resulting solid forms were characterized using Fourier Transform Infrared Spectroscopy (FTIR), Differential Scanning Calorimetry (DSC), and powder X-Ray Diffraction (PXRD). In addition, Single-Crystal X-Ray Diffraction (SCXRD) was used to elucidate detailed structural information on the novel multicomponent crystals formed. Successful preparation of midazolam free base from the hydrochloride salt was confirmed through FTIR, DSC, and PXRD analysis. Different co-crystals and salts of midazolam with coformers such as salicylic acid (SA), benzoic acid (BA), 3-hydroxybenzoic acid (3-HBA) and p-aminobenzoic acid (PABA) were synthesized and characterized. The structure of the single crystal obtained from a veterinary tranquilizer solution was solved and found to be a salt that had formed between midazolam free base, midazolam HCl, and methyl paraben. This finding inspired further investigation of similar multicomponent crystals of midazolam and methyl paraben analogues. This study demonstrated the effectiveness of both mechanochemical and slow evaporation methods for the preparation of multicomponent crystals. PXRD and DSC provided insights into the stability and purity of the crystals that had formed and the differences in melting points and PXRD patterns were particularly important in this regard. Differences in FTIR spectra were used to distinguish between different solid forms and to confirm the successful formation of new solid forms. Extensive searches in the Cambridge Structural Database (CSD) confirmed that the multicomponent crystals of midazolam, such as MDZ‧SA, MDZ‧BA, MDZ‧3-HBA, and MDZ‧PABA, had not previously been reported, highlighting the novelty of these findings. The research successfully isolated and characterized several novel multicomponent crystals of midazolam, demonstrating the potential of mechanochemistry and solvent evaporation techniques in the development of pharmaceutical and veterinary medicinal applications. These findings contribute to the understanding of cocrystal formation and provide a foundation for future studies in which the stability and efficacy of midazolam-based formulations can be evaluated. , Thesis (MSc) -- Faculty of Science, Chemistry, 2024
- Full Text:
- Date Issued: 2024-10-11
- Authors: Mngwengwe, Bongeka Naledi Precious
- Date: 2024-10-11
- Subjects: Uncatalogued
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/464532 , vital:76519
- Description: Midazolam, a 1,4-benzodiazepine derivative is commonly used to treat anxiety, insomnia and may be used as a sedative in anaesthesia as it has calming, anti-convulsant and muscle relaxant properties. Midazolam has a rapid onset but a short duration of action resulting in fewer adverse effects. Midazolam also has the potential to form insoluble crystalline precipitates in pharmaceutical dosage forms such as syrups and solutions, which is a challenge in formulation and process development activities. The primary goal of this research was to prepare multicomponent crystals of midazolam free base, specifically targeting interactions with coformers structurally similar to methyl paraben. Key preparation techniques included neat grinding, liquid-assisted grinding, and slow evaporation. The resulting solid forms were characterized using Fourier Transform Infrared Spectroscopy (FTIR), Differential Scanning Calorimetry (DSC), and powder X-Ray Diffraction (PXRD). In addition, Single-Crystal X-Ray Diffraction (SCXRD) was used to elucidate detailed structural information on the novel multicomponent crystals formed. Successful preparation of midazolam free base from the hydrochloride salt was confirmed through FTIR, DSC, and PXRD analysis. Different co-crystals and salts of midazolam with coformers such as salicylic acid (SA), benzoic acid (BA), 3-hydroxybenzoic acid (3-HBA) and p-aminobenzoic acid (PABA) were synthesized and characterized. The structure of the single crystal obtained from a veterinary tranquilizer solution was solved and found to be a salt that had formed between midazolam free base, midazolam HCl, and methyl paraben. This finding inspired further investigation of similar multicomponent crystals of midazolam and methyl paraben analogues. This study demonstrated the effectiveness of both mechanochemical and slow evaporation methods for the preparation of multicomponent crystals. PXRD and DSC provided insights into the stability and purity of the crystals that had formed and the differences in melting points and PXRD patterns were particularly important in this regard. Differences in FTIR spectra were used to distinguish between different solid forms and to confirm the successful formation of new solid forms. Extensive searches in the Cambridge Structural Database (CSD) confirmed that the multicomponent crystals of midazolam, such as MDZ‧SA, MDZ‧BA, MDZ‧3-HBA, and MDZ‧PABA, had not previously been reported, highlighting the novelty of these findings. The research successfully isolated and characterized several novel multicomponent crystals of midazolam, demonstrating the potential of mechanochemistry and solvent evaporation techniques in the development of pharmaceutical and veterinary medicinal applications. These findings contribute to the understanding of cocrystal formation and provide a foundation for future studies in which the stability and efficacy of midazolam-based formulations can be evaluated. , Thesis (MSc) -- Faculty of Science, Chemistry, 2024
- Full Text:
- Date Issued: 2024-10-11
Co-management and social equity at Silaka and Hluleka Nature Reserves, South Africa
- Authors: Mtshintsho, Anda
- Date: 2024-10-11
- Subjects: Uncatalogued
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/464834 , vital:76549
- Description: Co-management of protected areas (PAs) is a desired conservation approach aimed at balancing ecological goals and livelihood needs. Central to co-management are issues related to power sharing, responsibilities and benefit sharing. However, there still remains a dominance of an ecological emphasis in PA management, with studies focusing more on ‘objective’ biodiversity indicators for measuring the effectiveness of protected areas. However, focusing only on ecological indicators addresses a narrow perspective of achieving ecological integrity and misses social dimensions that, in some cases, might be considered more important than technical considerations. Particularly, in contexts with a history of socio-physical displacement of Indigenous people and local communities (IPLC), the social dimensions of wellbeing are complexly embedded into the economic and ecological dimensions, such that ignoring these linkages might jeopardise the success of protected areas. Thus, the aim of this study was to examine the state of research and conceptual advances on social indicators of conservation success in co-managed PAs and stakeholder views and perceptions on socially just conservation in co-managed protected areas in Silaka and Hluleka Nature Reserves, South Africa. To achieve this, a scoping review, semi-structured interviews and futures workshops (using the three horizons framework) were conducted. Findings from the scoping review (chapter 2) revealed that much of the reported social monitoring indicators still rely on quantifiable metrics (i.e., economic benefits) and less on subjective and relational metrics (i.e., qualitative strength of social networks and perceptions). Unsurprisingly, many of the reviewed case studies revealed the use of participation as an indicator of evaluating co-management success. Further, the interviews and futures workshop results in chapter 3 showed that the non-accrual of key co-management expectations such as the employment of local people, benefit-sharing (material or otherwise), participation in decision-making and community development has led to heightened conflicts between the reserve management agency and local people. Consequently, the respondents did not value the co-management arrangements, citing unfulfilled promises. Broadly, the findings of this study emphasise the need for collective and collaborative efforts in developing indicators that are not only socially just but those that are context dependent and sensitive. , Thesis (MSc) -- Faculty of Science, Environmental Science, 2024
- Full Text:
- Date Issued: 2024-10-11
- Authors: Mtshintsho, Anda
- Date: 2024-10-11
- Subjects: Uncatalogued
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/464834 , vital:76549
- Description: Co-management of protected areas (PAs) is a desired conservation approach aimed at balancing ecological goals and livelihood needs. Central to co-management are issues related to power sharing, responsibilities and benefit sharing. However, there still remains a dominance of an ecological emphasis in PA management, with studies focusing more on ‘objective’ biodiversity indicators for measuring the effectiveness of protected areas. However, focusing only on ecological indicators addresses a narrow perspective of achieving ecological integrity and misses social dimensions that, in some cases, might be considered more important than technical considerations. Particularly, in contexts with a history of socio-physical displacement of Indigenous people and local communities (IPLC), the social dimensions of wellbeing are complexly embedded into the economic and ecological dimensions, such that ignoring these linkages might jeopardise the success of protected areas. Thus, the aim of this study was to examine the state of research and conceptual advances on social indicators of conservation success in co-managed PAs and stakeholder views and perceptions on socially just conservation in co-managed protected areas in Silaka and Hluleka Nature Reserves, South Africa. To achieve this, a scoping review, semi-structured interviews and futures workshops (using the three horizons framework) were conducted. Findings from the scoping review (chapter 2) revealed that much of the reported social monitoring indicators still rely on quantifiable metrics (i.e., economic benefits) and less on subjective and relational metrics (i.e., qualitative strength of social networks and perceptions). Unsurprisingly, many of the reviewed case studies revealed the use of participation as an indicator of evaluating co-management success. Further, the interviews and futures workshop results in chapter 3 showed that the non-accrual of key co-management expectations such as the employment of local people, benefit-sharing (material or otherwise), participation in decision-making and community development has led to heightened conflicts between the reserve management agency and local people. Consequently, the respondents did not value the co-management arrangements, citing unfulfilled promises. Broadly, the findings of this study emphasise the need for collective and collaborative efforts in developing indicators that are not only socially just but those that are context dependent and sensitive. , Thesis (MSc) -- Faculty of Science, Environmental Science, 2024
- Full Text:
- Date Issued: 2024-10-11
Cocrystals, salts and eutectics of anti-tuberculosis medicines
- Authors: Matlapeng, Tsebang Alice
- Date: 2024-10-11
- Subjects: Uncatalogued
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/464521 , vital:76518
- Description: Tuberculosis remains as a prominent cause of death worldwide. This infectious disease is treated with first and second line drugs. However, challenges of multi drug resistant tuberculosis and adverse side effects such as depletion of essential B group vitamins in the body by first line drugs, as well as poor physicochemical properties of second line drugs persist. Cocrystallisation of anti-tubercular drugs with various coformers has therefore been used as an alternative method to improve the physicochemical properties of active pharmaceutical ingredients (API) while maintaining their efficacy. The main objective of this study was to carry out cocrystal screening of anti-tubercular API and vitamin B coformers to make drug-drug or drug-vitamin multicomponent complexes. Preparation of the multicomponent complexes was carried out by mechanochemical grinding (neat grinding (NG), liquid assisted grinding (LAG) and slow evaporation. All complexes were characterised using Fourier-transform infrared spectroscopy (FTIR), powder X-ray diffraction (PXRD), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA) and crystal structures were elucidated using single-crystal X-ray diffraction (SCXRD). The cocrystal screening resulted in the formation of various solid forms, which included cocrystals, salts and eutectic products. Two cocrystals of 4-aminosalicylic acid (PAS) were isolated and characterised. The cocrystal of PAS with isoniazid (INH) demonstrated similar characteristics for both the bulk crystalline material and milled materials. The cocrystal of PAS and pyrazinamide (PYR) prepared using mechanochemical synthesis was met with challenges, while difficulties were also encountered in obtaining suitable crystals for SCXRD analysis. The ground and recrystallised samples of the PAS and pyrazinecarboxylic acid (PCBA) showed distinct differences in their thermal behaviour, with SCXRD revealing the decomposition product phenolammonium-pyrazinecarboxylate salt ‘sans’ the CO2 moiety. Salt formation involving pyridoxine (PN) yielded a salt hydrate with PAS (PN-PAS) and an anhydrous salt with PCBA (PN-PCBA). Both salts exhibited very complex packing arrangements with equally complex thermal behaviour depending on the solvent used during preparation, and the method of preparation. Three eutectic systems involving INH with PYR, PN and pyridoxine hydrochloride (PNꞏHCl) were identified, and their phase diagrams were constructed from DSC data. The eutectic compositions obtained were 1:1 for INH:PYR, 1:1 for INH:PN and 6:4 for INH:PNꞏHCl. Finally, a total of eight multicomponent complexes were prepared using selected API and vitamin B6 components. The results presented here provide motivation for further investigation and evaluation of the pharmacochemical properties of these API. , Thesis (MSc) -- Faculty of Science, Chemistry, 2024
- Full Text:
- Date Issued: 2024-10-11
- Authors: Matlapeng, Tsebang Alice
- Date: 2024-10-11
- Subjects: Uncatalogued
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/464521 , vital:76518
- Description: Tuberculosis remains as a prominent cause of death worldwide. This infectious disease is treated with first and second line drugs. However, challenges of multi drug resistant tuberculosis and adverse side effects such as depletion of essential B group vitamins in the body by first line drugs, as well as poor physicochemical properties of second line drugs persist. Cocrystallisation of anti-tubercular drugs with various coformers has therefore been used as an alternative method to improve the physicochemical properties of active pharmaceutical ingredients (API) while maintaining their efficacy. The main objective of this study was to carry out cocrystal screening of anti-tubercular API and vitamin B coformers to make drug-drug or drug-vitamin multicomponent complexes. Preparation of the multicomponent complexes was carried out by mechanochemical grinding (neat grinding (NG), liquid assisted grinding (LAG) and slow evaporation. All complexes were characterised using Fourier-transform infrared spectroscopy (FTIR), powder X-ray diffraction (PXRD), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA) and crystal structures were elucidated using single-crystal X-ray diffraction (SCXRD). The cocrystal screening resulted in the formation of various solid forms, which included cocrystals, salts and eutectic products. Two cocrystals of 4-aminosalicylic acid (PAS) were isolated and characterised. The cocrystal of PAS with isoniazid (INH) demonstrated similar characteristics for both the bulk crystalline material and milled materials. The cocrystal of PAS and pyrazinamide (PYR) prepared using mechanochemical synthesis was met with challenges, while difficulties were also encountered in obtaining suitable crystals for SCXRD analysis. The ground and recrystallised samples of the PAS and pyrazinecarboxylic acid (PCBA) showed distinct differences in their thermal behaviour, with SCXRD revealing the decomposition product phenolammonium-pyrazinecarboxylate salt ‘sans’ the CO2 moiety. Salt formation involving pyridoxine (PN) yielded a salt hydrate with PAS (PN-PAS) and an anhydrous salt with PCBA (PN-PCBA). Both salts exhibited very complex packing arrangements with equally complex thermal behaviour depending on the solvent used during preparation, and the method of preparation. Three eutectic systems involving INH with PYR, PN and pyridoxine hydrochloride (PNꞏHCl) were identified, and their phase diagrams were constructed from DSC data. The eutectic compositions obtained were 1:1 for INH:PYR, 1:1 for INH:PN and 6:4 for INH:PNꞏHCl. Finally, a total of eight multicomponent complexes were prepared using selected API and vitamin B6 components. The results presented here provide motivation for further investigation and evaluation of the pharmacochemical properties of these API. , Thesis (MSc) -- Faculty of Science, Chemistry, 2024
- Full Text:
- Date Issued: 2024-10-11
Comparative analysis of YOLOV5 and YOLOV8 for automated fish detection and classification in underwater environments
- Authors: Kuhlane, Luxolo
- Date: 2024-10-11
- Subjects: Uncatalogued
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/464333 , vital:76502
- Description: The application of traditional manual techniques for fish detection and classification faces significant challenges, primarily stemming from their labour-intensive nature and limited scalability. Automating these kinds of processes through computer vision practices and machine learning techniques has emerged as a potential solution in recent years. With the development of and increase in ease of access to new technology in recent years, the use of a deep learning object detector known as YOLO (You Only Look Once) in the detection and classification of fish has steadily become notably popular. This thesis thus explores suitable YOLO architectures for detecting and classifying fish. The YOLOv5 and YOLOv8 models were evaluated explicitly for detecting and classifying fish in underwater environments. The selection of these models was based on a literature review highlighting their success in similar applications but remains largely understudied in underwater environments. Therefore, the effectiveness of these models was evaluated through comprehensive experimentation on collected and publicly available underwater fish datasets. In collaboration with the South African Institute of Biodiversity (SAIAB), five datasets were collected and manually annotated for labels for supervised machine learning. Moreover, two publicly available datasets were sourced for comparison to the literature. Furthermore, after determining that the smallest YOLO architectures are better suited to these imbalanced datasets, hyperparameter tuning tailored the models to the characteristics of the various underwater environments used in the research. The popular DeepFish dataset was evaluated to establish a baseline and feasibility of these models in the understudied domain. The results demonstrated high detection accuracy for both YOLOv5 and YOLOv8. However, YOLOv8 outperformed YOLOv5, achieving 97.43% accuracy compared to 94.53%. After experiments on seven datasets, trends revealed YOLOv8’s enhanced generalisation accuracy due to architectural improvements, particularly in detecting smaller fish. Overall, YOLOv8 demonstrated that it is the better fish detection and classification model on diverse data. , Thesis (MSc) -- Faculty of Science, Computer Science, 2024
- Full Text:
- Date Issued: 2024-10-11
- Authors: Kuhlane, Luxolo
- Date: 2024-10-11
- Subjects: Uncatalogued
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/464333 , vital:76502
- Description: The application of traditional manual techniques for fish detection and classification faces significant challenges, primarily stemming from their labour-intensive nature and limited scalability. Automating these kinds of processes through computer vision practices and machine learning techniques has emerged as a potential solution in recent years. With the development of and increase in ease of access to new technology in recent years, the use of a deep learning object detector known as YOLO (You Only Look Once) in the detection and classification of fish has steadily become notably popular. This thesis thus explores suitable YOLO architectures for detecting and classifying fish. The YOLOv5 and YOLOv8 models were evaluated explicitly for detecting and classifying fish in underwater environments. The selection of these models was based on a literature review highlighting their success in similar applications but remains largely understudied in underwater environments. Therefore, the effectiveness of these models was evaluated through comprehensive experimentation on collected and publicly available underwater fish datasets. In collaboration with the South African Institute of Biodiversity (SAIAB), five datasets were collected and manually annotated for labels for supervised machine learning. Moreover, two publicly available datasets were sourced for comparison to the literature. Furthermore, after determining that the smallest YOLO architectures are better suited to these imbalanced datasets, hyperparameter tuning tailored the models to the characteristics of the various underwater environments used in the research. The popular DeepFish dataset was evaluated to establish a baseline and feasibility of these models in the understudied domain. The results demonstrated high detection accuracy for both YOLOv5 and YOLOv8. However, YOLOv8 outperformed YOLOv5, achieving 97.43% accuracy compared to 94.53%. After experiments on seven datasets, trends revealed YOLOv8’s enhanced generalisation accuracy due to architectural improvements, particularly in detecting smaller fish. Overall, YOLOv8 demonstrated that it is the better fish detection and classification model on diverse data. , Thesis (MSc) -- Faculty of Science, Computer Science, 2024
- Full Text:
- Date Issued: 2024-10-11
Computational search for nature-derived dual-action inhibitors of HIV-1 reverse transcriptase and integrase: a potential strategy to mitigate drug resistance progression
- Authors: Mwiinga, Luyando
- Date: 2024-10-11
- Subjects: HIV (Viruses) , Reverse transcriptase , Antiretroviral agents , RDKit , Drug resistance , Docking
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/463930 , vital:76458
- Description: Human immunodeficiency virus Type 1 (HIV-1) is a devastating viral infection affecting millions worldwide and presents significant challenges in treatment and management. In 2022, approximately 39 million people were living with HIV with Sub-Saharan Africa having two thirds of these infections. Devastatingly, there were approximately 300 000 HIV/AIDS related deaths in Sub-Saharan Africa alone in 2022 alone. Antiretroviral therapy (ART) which is fundamental for HIV treatment, comprises of a combination of drugs such as nucleoside reverse transcriptase inhibitors (NRTIs), non-nucleoside reverse transcriptase inhibitors (NNRTs), protease inhibitors (PIs) and integrase strand transfer inhibitors (INSTIs). However, although 28.7 million people out of the estimated 38.4 million people living with HIV in 2021 were receiving ART, the emergence of drug-resistant strains further complicates treatment efforts, highlighting the need for novel therapeutic approaches. This study aimed to address the challenges raised by drug resistance and significant side effects by identifying potential dual inhibitors against HIV-1 Reverse Transcriptase (RT) and Integrase (IN) using in silico techniques. RT RNase H and IN were chosen as targets for their shared dependency on Mg2+ ions within their active sites, which are crucial for catalytic activity. The selection of dual inhibitors was motivated by the fact that the virus would need to replicate at two points simultaneously to develop resistance, making it less likely. The objectives of this study included the creation of a natural derivative compound library using RDKit with the aid of SciFinder, utilizing (-)-epigallocatechin-3-O-gallate (EGCG), because of its dual inhibitory effects against RT and IN, as indicated by a study conducted by Sanna et al. 2019. The natural derivatives were chosen to take advantage of their chemical diversity and to explore potential novel therapeutic options for combating HIV drug resistance. The compound library created comprised of 125 203 compounds. Then docking studies were conducted to assess proteinligand binding. After the correlation of the RT and IN docking studies, 288 compounds were filtered to have potential dual inhibitory activity. Then quantitative estimation of druggability (QED) analysis identified three compounds with superior properties compared to EGCG and FDAapproved drug raltegravir (RAL). Molecular docking simulations revealed interactions between the inhibitors and the key active site residues of RT and IN, along with the chelation of at least one 3 Mg2+, suggesting the potential for enzymatic disruption. Furthermore, molecular dynamic (MD) simulations were then conducted to assess protein-ligand system behavior, through RMSD and RMSF analysis. The RMSD analysis uncovered instability in the IN-Sci30703 complex, leading to its exclusion as a potential dual action inhibitor. RMSF analysis for IN showed that all the inhibitors had the ability to limit the flexibility of the catalytic loop which is essential for catalytic activity. Therefore, further in vitro studies are required to evaluate the effectiveness of the remaining two EGCG derivatives (Sci33211 and Sci48919) in inhibiting RT and IN through the chelation of at least one Mg2+ ion to determine if they have superior dual inhibitory effects compared to EGCG. This study adds to the ongoing efforts to develop effective strategies against HIV-1 drug resistance and emphasizes the importance of continued research in this field. , Thesis (MSc) -- Faculty of Science, Biochemistry, Microbiology & Bioinformatics, 2024
- Full Text:
- Date Issued: 2024-10-11
- Authors: Mwiinga, Luyando
- Date: 2024-10-11
- Subjects: HIV (Viruses) , Reverse transcriptase , Antiretroviral agents , RDKit , Drug resistance , Docking
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/463930 , vital:76458
- Description: Human immunodeficiency virus Type 1 (HIV-1) is a devastating viral infection affecting millions worldwide and presents significant challenges in treatment and management. In 2022, approximately 39 million people were living with HIV with Sub-Saharan Africa having two thirds of these infections. Devastatingly, there were approximately 300 000 HIV/AIDS related deaths in Sub-Saharan Africa alone in 2022 alone. Antiretroviral therapy (ART) which is fundamental for HIV treatment, comprises of a combination of drugs such as nucleoside reverse transcriptase inhibitors (NRTIs), non-nucleoside reverse transcriptase inhibitors (NNRTs), protease inhibitors (PIs) and integrase strand transfer inhibitors (INSTIs). However, although 28.7 million people out of the estimated 38.4 million people living with HIV in 2021 were receiving ART, the emergence of drug-resistant strains further complicates treatment efforts, highlighting the need for novel therapeutic approaches. This study aimed to address the challenges raised by drug resistance and significant side effects by identifying potential dual inhibitors against HIV-1 Reverse Transcriptase (RT) and Integrase (IN) using in silico techniques. RT RNase H and IN were chosen as targets for their shared dependency on Mg2+ ions within their active sites, which are crucial for catalytic activity. The selection of dual inhibitors was motivated by the fact that the virus would need to replicate at two points simultaneously to develop resistance, making it less likely. The objectives of this study included the creation of a natural derivative compound library using RDKit with the aid of SciFinder, utilizing (-)-epigallocatechin-3-O-gallate (EGCG), because of its dual inhibitory effects against RT and IN, as indicated by a study conducted by Sanna et al. 2019. The natural derivatives were chosen to take advantage of their chemical diversity and to explore potential novel therapeutic options for combating HIV drug resistance. The compound library created comprised of 125 203 compounds. Then docking studies were conducted to assess proteinligand binding. After the correlation of the RT and IN docking studies, 288 compounds were filtered to have potential dual inhibitory activity. Then quantitative estimation of druggability (QED) analysis identified three compounds with superior properties compared to EGCG and FDAapproved drug raltegravir (RAL). Molecular docking simulations revealed interactions between the inhibitors and the key active site residues of RT and IN, along with the chelation of at least one 3 Mg2+, suggesting the potential for enzymatic disruption. Furthermore, molecular dynamic (MD) simulations were then conducted to assess protein-ligand system behavior, through RMSD and RMSF analysis. The RMSD analysis uncovered instability in the IN-Sci30703 complex, leading to its exclusion as a potential dual action inhibitor. RMSF analysis for IN showed that all the inhibitors had the ability to limit the flexibility of the catalytic loop which is essential for catalytic activity. Therefore, further in vitro studies are required to evaluate the effectiveness of the remaining two EGCG derivatives (Sci33211 and Sci48919) in inhibiting RT and IN through the chelation of at least one Mg2+ ion to determine if they have superior dual inhibitory effects compared to EGCG. This study adds to the ongoing efforts to develop effective strategies against HIV-1 drug resistance and emphasizes the importance of continued research in this field. , Thesis (MSc) -- Faculty of Science, Biochemistry, Microbiology & Bioinformatics, 2024
- Full Text:
- Date Issued: 2024-10-11
Connecting culture and science: Utilising Oshikundu and Ombidi in biology lessons on diffusion and osmosis
- Shilomboleni, Helena Ilena Ndilimeke
- Authors: Shilomboleni, Helena Ilena Ndilimeke
- Date: 2024-10-11
- Subjects: Uncatalogued
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/463636 , vital:76427
- Description: Various science curricula including that of Namibia recommend that teaching and learning should start with the knowledge and experiences of learners from their homes and communities. These experiences are the learners’ Indigenous Knowledge (IK) which should be integrated to make science accessible and relevant to learners from diverse sociocultural backgrounds. This suggests that science teachers are encouraged to integrate IK into their teaching to help learners grasp abstract concepts and construct their own understanding of phenomena. However, much literature has revealed that many teachers find it difficult to integrate IK into their science teaching. Some scholars further argue that teachers lack the pedagogical content knowledge to effectively integrate IK. I assume this could be because the science curriculum is not explicit on how IK should be integrated into science teaching. It is against this backdrop that in this study I mobilised the Indigenous technologies of making oshikundu and preserving ombidi to support Grade 10 Biology learners in talking and making sense of diffusion and osmosis. This study was underpinned by the interpretivist and Indigenous research paradigms. Within the Indigenous research paradigm, I focused on Ubuntu as a perspective. A qualitative case study was employed and conducted at a certain school in the northern part of Namibia, in the Ohangwena region. I worked with a group of 35 Grade 10 learners, two Indigenous Knowledge Custodians (KCs) who are the custodians of cultural heritage and one Biology teacher (critical friend) as participants in this study. Qualitative data were collected using a focus group interview (sharing circle), group activity, participatory observation, and learners’ journal reflections. Vygotsky’s sociocultural theory together with Ogunniyi’s Contiguity Argumentative Theory were used as lenses to analyse data. The findings of the study revealed that during the IKCs’ practical demonstrations learners were able to identify science concepts embedded in the cultural practices of making oshikundu and preserving ombidi. The findings further revealed that the practical demonstrations enhanced active participation and interactions among learners. I thus recommend that teachers should tap into IKCs’ cultural heritage by inviting them into their classrooms to make science relevant, accessible and meaningful to learners. , Thesis (MEd) -- Faculty of Education, Secondary and Post-School Education, 2024
- Full Text:
- Date Issued: 2024-10-11
- Authors: Shilomboleni, Helena Ilena Ndilimeke
- Date: 2024-10-11
- Subjects: Uncatalogued
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/463636 , vital:76427
- Description: Various science curricula including that of Namibia recommend that teaching and learning should start with the knowledge and experiences of learners from their homes and communities. These experiences are the learners’ Indigenous Knowledge (IK) which should be integrated to make science accessible and relevant to learners from diverse sociocultural backgrounds. This suggests that science teachers are encouraged to integrate IK into their teaching to help learners grasp abstract concepts and construct their own understanding of phenomena. However, much literature has revealed that many teachers find it difficult to integrate IK into their science teaching. Some scholars further argue that teachers lack the pedagogical content knowledge to effectively integrate IK. I assume this could be because the science curriculum is not explicit on how IK should be integrated into science teaching. It is against this backdrop that in this study I mobilised the Indigenous technologies of making oshikundu and preserving ombidi to support Grade 10 Biology learners in talking and making sense of diffusion and osmosis. This study was underpinned by the interpretivist and Indigenous research paradigms. Within the Indigenous research paradigm, I focused on Ubuntu as a perspective. A qualitative case study was employed and conducted at a certain school in the northern part of Namibia, in the Ohangwena region. I worked with a group of 35 Grade 10 learners, two Indigenous Knowledge Custodians (KCs) who are the custodians of cultural heritage and one Biology teacher (critical friend) as participants in this study. Qualitative data were collected using a focus group interview (sharing circle), group activity, participatory observation, and learners’ journal reflections. Vygotsky’s sociocultural theory together with Ogunniyi’s Contiguity Argumentative Theory were used as lenses to analyse data. The findings of the study revealed that during the IKCs’ practical demonstrations learners were able to identify science concepts embedded in the cultural practices of making oshikundu and preserving ombidi. The findings further revealed that the practical demonstrations enhanced active participation and interactions among learners. I thus recommend that teachers should tap into IKCs’ cultural heritage by inviting them into their classrooms to make science relevant, accessible and meaningful to learners. , Thesis (MEd) -- Faculty of Education, Secondary and Post-School Education, 2024
- Full Text:
- Date Issued: 2024-10-11
Design and fabrication of millifluidic devices for maintenance of tissue cultures under perfusion
- Buthelezi, Khanyisile Thando Fatima
- Authors: Buthelezi, Khanyisile Thando Fatima
- Date: 2024-10-11
- Subjects: Uncatalogued
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/464358 , vital:76504
- Description: Restricted access. Expected release in 2026. , Thesis (MSc) -- Faculty of Science, Biotechnology Innovation Centre, 2024
- Full Text:
- Date Issued: 2024-10-11
- Authors: Buthelezi, Khanyisile Thando Fatima
- Date: 2024-10-11
- Subjects: Uncatalogued
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/464358 , vital:76504
- Description: Restricted access. Expected release in 2026. , Thesis (MSc) -- Faculty of Science, Biotechnology Innovation Centre, 2024
- Full Text:
- Date Issued: 2024-10-11
Developing transformative community-university partnerships: a participatory assessment of Rhodes University community engagement monitoring and evaluation system
- Authors: Nkwinti, Nosipho
- Date: 2024-10-11
- Subjects: Uncatalogued
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/463592 , vital:76423
- Description: This thesis comprehensively explores transformative community engagement (CE) in higher education, focusing on the context of collaborative community-university partnerships (CUPs) in Makhanda, South Africa. The study aimed to assess and revise the monitoring and evaluation (M&E) system of the Rhodes University Community Engagement division to foster a transformation in CUPs. The research employs an exploratory design to understand the complexities of CUPs and improve the M&E systems by generating new concepts and ideas. A variety of qualitative methods, including focus groups, interviews, and document analysis, were utilized to engage community partners, student leaders, and Rhodes University Community Engagement staff. The participatory approach to research was critical, involving stakeholders in finalizing the M&E framework to ensure it met the shared objective. Data analysis was conducted inductively, with themes emerging from the data to facilitate a bottom-up understanding of the research questions. The study found that diverse community engagement projects at Rhodes University enhanced partnerships between the university and the local community in Makhanda. Participants shared varied understandings and experiences of Community Engagement. They saw CE as crucial for bridging the university-community divide and aiding local development. Furthermore, the research identified the need for a Monitoring and Evaluation system that supports collaborative Community-University Partnerships. Participants collaboratively developed and refined this M&E system, ensuring it aligns with community needs and promotes sustained development in Makhanda. Challenges such as diverse perspectives, logistical issues in focus groups, and power dynamics were also highlighted and addressed through an inclusive and participatory approach. This research highlights the elaborate distinctions of community engagement and the importance of such partnerships in fostering sustainable societal development. The framework developed has practical implications for shaping policies, fostering inclusivity, and promoting responsive university-community engagement that is aligned with community needs. The research concludes by suggesting the value of inclusivity, communication, and a flexible adaptation of practices to maximize the benefits of such partnerships. Future research could explore the longitudinal impacts of university-community partnerships, examine the scalability of the current framework to other universities, and evaluate the long-term socio-economic outcomes of the engaged citizen program on the community. , Thesis (MEd) -- Faculty of Education, Secondary and Post-School Education, 2024
- Full Text:
- Date Issued: 2024-10-11
- Authors: Nkwinti, Nosipho
- Date: 2024-10-11
- Subjects: Uncatalogued
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/463592 , vital:76423
- Description: This thesis comprehensively explores transformative community engagement (CE) in higher education, focusing on the context of collaborative community-university partnerships (CUPs) in Makhanda, South Africa. The study aimed to assess and revise the monitoring and evaluation (M&E) system of the Rhodes University Community Engagement division to foster a transformation in CUPs. The research employs an exploratory design to understand the complexities of CUPs and improve the M&E systems by generating new concepts and ideas. A variety of qualitative methods, including focus groups, interviews, and document analysis, were utilized to engage community partners, student leaders, and Rhodes University Community Engagement staff. The participatory approach to research was critical, involving stakeholders in finalizing the M&E framework to ensure it met the shared objective. Data analysis was conducted inductively, with themes emerging from the data to facilitate a bottom-up understanding of the research questions. The study found that diverse community engagement projects at Rhodes University enhanced partnerships between the university and the local community in Makhanda. Participants shared varied understandings and experiences of Community Engagement. They saw CE as crucial for bridging the university-community divide and aiding local development. Furthermore, the research identified the need for a Monitoring and Evaluation system that supports collaborative Community-University Partnerships. Participants collaboratively developed and refined this M&E system, ensuring it aligns with community needs and promotes sustained development in Makhanda. Challenges such as diverse perspectives, logistical issues in focus groups, and power dynamics were also highlighted and addressed through an inclusive and participatory approach. This research highlights the elaborate distinctions of community engagement and the importance of such partnerships in fostering sustainable societal development. The framework developed has practical implications for shaping policies, fostering inclusivity, and promoting responsive university-community engagement that is aligned with community needs. The research concludes by suggesting the value of inclusivity, communication, and a flexible adaptation of practices to maximize the benefits of such partnerships. Future research could explore the longitudinal impacts of university-community partnerships, examine the scalability of the current framework to other universities, and evaluate the long-term socio-economic outcomes of the engaged citizen program on the community. , Thesis (MEd) -- Faculty of Education, Secondary and Post-School Education, 2024
- Full Text:
- Date Issued: 2024-10-11
Developing transformative community-university partnerships: a participatory assessment of Rhodes University community engagement monitoring and evaluation system
- Authors: Nkwinti, Nosipho
- Date: 2024-10-11
- Subjects: Uncatalogued
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/463603 , vital:76424
- Description: This thesis comprehensively explores transformative community engagement (CE) in higher education, focusing on the context of collaborative community-university partnerships (CUPs) in Makhanda, South Africa. The study aimed to assess and revise the monitoring and evaluation (M&E) system of the Rhodes University Community Engagement division to foster a transformation in CUPs. The research employs an exploratory design to understand the complexities of CUPs and improve the M&E systems by generating new concepts and ideas. A variety of qualitative methods, including focus groups, interviews, and document analysis, were utilized to engage community partners, student leaders, and Rhodes University Community Engagement staff. The participatory approach to research was critical, involving stakeholders in finalizing the M&E framework to ensure it met the shared objective. Data analysis was conducted inductively, with themes emerging from the data to facilitate a bottom-up understanding of the research questions. The study found that diverse community engagement projects at Rhodes University enhanced partnerships between the university and the local community in Makhanda. Participants shared varied understandings and experiences of Community Engagement. They saw CE as crucial for bridging the university-community divide and aiding local development. Furthermore, the research identified the need for a Monitoring and Evaluation system that supports collaborative Community-University Partnerships. Participants collaboratively developed and refined this M&E system, ensuring it aligns with community needs and promotes sustained development in Makhanda. Challenges such as diverse perspectives, logistical issues in focus groups, and power dynamics were also highlighted and addressed through an inclusive and participatory approach. This research highlights the elaborate distinctions of community engagement and the importance of such partnerships in fostering sustainable societal development. The framework developed has practical implications for shaping policies, fostering inclusivity, and promoting responsive university-community engagement that is aligned with community needs. The research concludes by suggesting the value of inclusivity, communication, and a flexible adaptation of practices to maximize the benefits of such partnerships. Future research could explore the longitudinal impacts of university-community partnerships, examine the scalability of the current framework to other universities, and evaluate the long-term socio-economic outcomes of the engaged citizen program on the community. , Thesis (MEd) -- Faculty of Education, Secondary and Post-School Education, 2024
- Full Text:
- Date Issued: 2024-10-11
- Authors: Nkwinti, Nosipho
- Date: 2024-10-11
- Subjects: Uncatalogued
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/463603 , vital:76424
- Description: This thesis comprehensively explores transformative community engagement (CE) in higher education, focusing on the context of collaborative community-university partnerships (CUPs) in Makhanda, South Africa. The study aimed to assess and revise the monitoring and evaluation (M&E) system of the Rhodes University Community Engagement division to foster a transformation in CUPs. The research employs an exploratory design to understand the complexities of CUPs and improve the M&E systems by generating new concepts and ideas. A variety of qualitative methods, including focus groups, interviews, and document analysis, were utilized to engage community partners, student leaders, and Rhodes University Community Engagement staff. The participatory approach to research was critical, involving stakeholders in finalizing the M&E framework to ensure it met the shared objective. Data analysis was conducted inductively, with themes emerging from the data to facilitate a bottom-up understanding of the research questions. The study found that diverse community engagement projects at Rhodes University enhanced partnerships between the university and the local community in Makhanda. Participants shared varied understandings and experiences of Community Engagement. They saw CE as crucial for bridging the university-community divide and aiding local development. Furthermore, the research identified the need for a Monitoring and Evaluation system that supports collaborative Community-University Partnerships. Participants collaboratively developed and refined this M&E system, ensuring it aligns with community needs and promotes sustained development in Makhanda. Challenges such as diverse perspectives, logistical issues in focus groups, and power dynamics were also highlighted and addressed through an inclusive and participatory approach. This research highlights the elaborate distinctions of community engagement and the importance of such partnerships in fostering sustainable societal development. The framework developed has practical implications for shaping policies, fostering inclusivity, and promoting responsive university-community engagement that is aligned with community needs. The research concludes by suggesting the value of inclusivity, communication, and a flexible adaptation of practices to maximize the benefits of such partnerships. Future research could explore the longitudinal impacts of university-community partnerships, examine the scalability of the current framework to other universities, and evaluate the long-term socio-economic outcomes of the engaged citizen program on the community. , Thesis (MEd) -- Faculty of Education, Secondary and Post-School Education, 2024
- Full Text:
- Date Issued: 2024-10-11
Development of a novel agar-based microtitre plate system for construction of consistent biofilm models and subsequent use in antimicrobial screening
- Authors: Davies, Michaela Roxanne
- Date: 2024-10-11
- Subjects: Uncatalogued
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/464369 , vital:76505
- Description: Restricted access. Expected release in 2026. , Thesis (MSc) -- Faculty of Science, Biotechnology Innovation Centre, 2024
- Full Text:
- Date Issued: 2024-10-11
- Authors: Davies, Michaela Roxanne
- Date: 2024-10-11
- Subjects: Uncatalogued
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/464369 , vital:76505
- Description: Restricted access. Expected release in 2026. , Thesis (MSc) -- Faculty of Science, Biotechnology Innovation Centre, 2024
- Full Text:
- Date Issued: 2024-10-11
Development of efficient protocols to generate breast cancer spheroids for application in drug discovery
- Ntsoyi, Nomaphelo Ntombikayise
- Authors: Ntsoyi, Nomaphelo Ntombikayise
- Date: 2024-10-11
- Subjects: Uncatalogued
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/464380 , vital:76506
- Description: Restricted access. Expected release in 2026. , Thesis (MSc) -- Faculty of Science, Biotechnology Innovation Centre, 2024
- Full Text:
- Date Issued: 2024-10-11
- Authors: Ntsoyi, Nomaphelo Ntombikayise
- Date: 2024-10-11
- Subjects: Uncatalogued
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/464380 , vital:76506
- Description: Restricted access. Expected release in 2026. , Thesis (MSc) -- Faculty of Science, Biotechnology Innovation Centre, 2024
- Full Text:
- Date Issued: 2024-10-11
Do the Cytochrome P450 1A2 allele variations have an effect on the structure and function of the protein?
- Authors: Mondile, Queenie
- Date: 2024-10-11
- Subjects: Uncatalogued
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/463907 , vital:76456
- Description: Access restricted. Expected release in 2025. , Thesis (MSc) -- Faculty of Science, Biochemistry, Microbiology & Bioinformatics, 2024
- Full Text:
- Date Issued: 2024-10-11
- Authors: Mondile, Queenie
- Date: 2024-10-11
- Subjects: Uncatalogued
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/463907 , vital:76456
- Description: Access restricted. Expected release in 2025. , Thesis (MSc) -- Faculty of Science, Biochemistry, Microbiology & Bioinformatics, 2024
- Full Text:
- Date Issued: 2024-10-11
Drug development and animal welfare: bioethical analysis of emergency situations and the research settings
- Authors: Msimang, Asante
- Date: 2024-10-11
- Subjects: Uncatalogued
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/461852 , vital:76245
- Description: Access restricited. Expected release date 2026. , Thesis (Msc (Pharmacy)) -- Faculty of Pharmacy, Pharmacy, 2024
- Full Text:
- Date Issued: 2024-10-11
- Authors: Msimang, Asante
- Date: 2024-10-11
- Subjects: Uncatalogued
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/461852 , vital:76245
- Description: Access restricited. Expected release date 2026. , Thesis (Msc (Pharmacy)) -- Faculty of Pharmacy, Pharmacy, 2024
- Full Text:
- Date Issued: 2024-10-11
Elucidating the effect of potential mitochondrial toxicants on glucose handling and insulin signalling in skeletal muscle and liver cell lines in vitro
- Authors: Kuretu, Auxiliare
- Date: 2024-10-11
- Subjects: Uncatalogued
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/461830 , vital:76243
- Description: Access restricited. Expected release date 2026. , Thesis (Msc (Pharmacy)) -- Faculty of Pharmacy, Pharmacy, 2024
- Full Text:
- Date Issued: 2024-10-11
- Authors: Kuretu, Auxiliare
- Date: 2024-10-11
- Subjects: Uncatalogued
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/461830 , vital:76243
- Description: Access restricited. Expected release date 2026. , Thesis (Msc (Pharmacy)) -- Faculty of Pharmacy, Pharmacy, 2024
- Full Text:
- Date Issued: 2024-10-11
Encroaching species are stronger anisohydric “water spenders” under elevated CO2 conditions: implications for savanna seedling establishment rates
- Authors: Reynolds, Liam Macleod
- Date: 2024-10-11
- Subjects: Uncatalogued
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/465091 , vital:76572
- Description: Plant water transport systems play a fundamental role in the productivity and survival of terrestrial plants due to the vascular architecture placing a physical limit on metabolic function. Savannas have high variability in rainfall, leading multiple studies to suggest that plant water-use strategies are key mechanisms affecting seedling establishment rates. Many savannas are seeing a directional shift towards an increase in the abundance of certain woody species through a process known as bush encroachment, which has been largely attributed to the fertilising effect of rising atmospheric [CO2] on C3 trees. These species are classified as encroachers. While there have been multiple studies investigating changes in the physiology of savanna species under elevated CO2 (eCO2), few have examined how climate and eCO2 affects the fundamental water-use strategies in the seedling stage, a crucial demographic bottleneck. Here, this research provides valuable insights into the mechanisms behind bush encroachment in the context of eCO2 using results from a pot experiment at the Rhodes University Elevated CO2 facility and a field experiment. All species showed water use strategies characteristic of anisohydric “water-spenders”, however, the vulnerability to embolism and rates of water-use were different between encroachers and non-encroachers. Encroachers are better at taking advantage of water pulses, particularly under eCO2 and grass competition. This comes at the cost of higher xylem vulnerability during drought, leading to reductions in conductance when exposed to heavy water stress. The response of the photosynthetic parameters mirrored this, with encroaching species had higher rates of photosynthesis and photosystem II quantum yield than non-encroachers under the well-watered treatments. Field experiments revealed that small trees are particularly vulnerable to drought stress, when compared to medium and large trees. The outcomes of this complex response will largely depend on the extent of changes to biotic and abiotic factors across spatial and temporal zones caused by climate change. This research highlights potential hydraulic mechanisms contributing to the increase in bush encroachment, as well as providing important insights into the determinant factors that make a savanna species capable of encroachment. , Thesis (MSc) -- Faculty of Science, Botany, 2024
- Full Text:
- Date Issued: 2024-10-11
- Authors: Reynolds, Liam Macleod
- Date: 2024-10-11
- Subjects: Uncatalogued
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/465091 , vital:76572
- Description: Plant water transport systems play a fundamental role in the productivity and survival of terrestrial plants due to the vascular architecture placing a physical limit on metabolic function. Savannas have high variability in rainfall, leading multiple studies to suggest that plant water-use strategies are key mechanisms affecting seedling establishment rates. Many savannas are seeing a directional shift towards an increase in the abundance of certain woody species through a process known as bush encroachment, which has been largely attributed to the fertilising effect of rising atmospheric [CO2] on C3 trees. These species are classified as encroachers. While there have been multiple studies investigating changes in the physiology of savanna species under elevated CO2 (eCO2), few have examined how climate and eCO2 affects the fundamental water-use strategies in the seedling stage, a crucial demographic bottleneck. Here, this research provides valuable insights into the mechanisms behind bush encroachment in the context of eCO2 using results from a pot experiment at the Rhodes University Elevated CO2 facility and a field experiment. All species showed water use strategies characteristic of anisohydric “water-spenders”, however, the vulnerability to embolism and rates of water-use were different between encroachers and non-encroachers. Encroachers are better at taking advantage of water pulses, particularly under eCO2 and grass competition. This comes at the cost of higher xylem vulnerability during drought, leading to reductions in conductance when exposed to heavy water stress. The response of the photosynthetic parameters mirrored this, with encroaching species had higher rates of photosynthesis and photosystem II quantum yield than non-encroachers under the well-watered treatments. Field experiments revealed that small trees are particularly vulnerable to drought stress, when compared to medium and large trees. The outcomes of this complex response will largely depend on the extent of changes to biotic and abiotic factors across spatial and temporal zones caused by climate change. This research highlights potential hydraulic mechanisms contributing to the increase in bush encroachment, as well as providing important insights into the determinant factors that make a savanna species capable of encroachment. , Thesis (MSc) -- Faculty of Science, Botany, 2024
- Full Text:
- Date Issued: 2024-10-11
Enhancing licence plate recognition for a robust vehicle re-identification system
- Authors: Boby, Alden Zachary
- Date: 2024-10-11
- Subjects: Automobile theft South Africa , Deep learning (Machine learning) , Object detection , YOLOv7 , YOLO , Pattern recognition systems , Image processing Digital techniques , Automobile license plates
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/464322 , vital:76501
- Description: Vehicle security is a growing concern for citizens of South Africa. Law enforcement relies on reports and security camera footage for vehicle identification but struggles to match the increasing number of carjacking incidents and low vehicle recovery rates. Security camera footage offers an accessible means to identify stolen vehicles, yet it often poses hurdles like anamorphic plates and low resolution. Furthermore, depending on human operators proves inefficient, requiring faster processes to improve vehicle recovery rates and trust in law enforcement. The integration of deep learning has revolutionised object detection algorithms, increasing the popularity of vehicle tracking for security purposes. This thesis investigates advanced deep-learning methods for a comprehensive vehicle search and re-identification system. It enhances YOLOv7’s algorithmic capabilities and employs preprocessing techniques like super-resolution and perspective correction via the Improved Warped Planar Object Detection network for more effective licence plate optical character recognition. Key contributions include a specifically annotated dataset for training object detection models, an optical character recognition model based on YOLOv7, and a method for identifying vehicles in unrestricted data. The system detected rectangular and square licence plates without prior shape knowledge, achieving a 98.7% character recognition rate compared to 95.31% in related work. Moreover, it outperformed traditional optical character recognition by 28.25% and deep-learning EasyOCR by 14.18%. Its potential applications in law enforcement, traffic management, and parking systems can improve surveillance and security through automation. , Thesis (MSc) -- Faculty of Science, Computer Science, 2024
- Full Text:
- Date Issued: 2024-10-11
- Authors: Boby, Alden Zachary
- Date: 2024-10-11
- Subjects: Automobile theft South Africa , Deep learning (Machine learning) , Object detection , YOLOv7 , YOLO , Pattern recognition systems , Image processing Digital techniques , Automobile license plates
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/464322 , vital:76501
- Description: Vehicle security is a growing concern for citizens of South Africa. Law enforcement relies on reports and security camera footage for vehicle identification but struggles to match the increasing number of carjacking incidents and low vehicle recovery rates. Security camera footage offers an accessible means to identify stolen vehicles, yet it often poses hurdles like anamorphic plates and low resolution. Furthermore, depending on human operators proves inefficient, requiring faster processes to improve vehicle recovery rates and trust in law enforcement. The integration of deep learning has revolutionised object detection algorithms, increasing the popularity of vehicle tracking for security purposes. This thesis investigates advanced deep-learning methods for a comprehensive vehicle search and re-identification system. It enhances YOLOv7’s algorithmic capabilities and employs preprocessing techniques like super-resolution and perspective correction via the Improved Warped Planar Object Detection network for more effective licence plate optical character recognition. Key contributions include a specifically annotated dataset for training object detection models, an optical character recognition model based on YOLOv7, and a method for identifying vehicles in unrestricted data. The system detected rectangular and square licence plates without prior shape knowledge, achieving a 98.7% character recognition rate compared to 95.31% in related work. Moreover, it outperformed traditional optical character recognition by 28.25% and deep-learning EasyOCR by 14.18%. Its potential applications in law enforcement, traffic management, and parking systems can improve surveillance and security through automation. , Thesis (MSc) -- Faculty of Science, Computer Science, 2024
- Full Text:
- Date Issued: 2024-10-11
Evaluating baculovirus mixtures against false codling moth Thaumatotibia leucotreta Meyrick. (Lepidoptera: Tortricidae)
- Authors: Tole, Siviwe
- Date: 2024-10-11
- Subjects: False codling moth Biological control , Baculoviruses , Integrated pest management , Natural pesticides , Granulovirus
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/463996 , vital:76464
- Description: False codling moth (FCM), Thaumatotibia leucotreta, is an important pest of citrus, stone fruit, avocados, peppers, and other important agricultural crops in southern Africa. Baculovirus-based biopesticides are components in an integrated pest management (IPM) programme to manage the pest in the field. Cryptogran™ and Cryptex™ which are CrleGV-SA based-biopesticides have been effective in the control of T. leucotreta for the past 15 years. Recently, CrpeNPV-based Multimax™ and Codlmax™ have been commercialised to control T. leucotreta and other important agricultural pests. Despite these viruses being relatively host-specific and safe to humans and animals in comparison to chemical insecticides, their application is hindered by their slow speed of kill, sensitivity to UV light, and the potential for insect resistance. Research investigating the effects of mixed baculoviral interactions against target pests has been a growing field of interest due to their potential to overcome such shortcomings. Previous studies using a combination of CrleGV-SA and CrpeNPV against T. leucotreta observed a reduction in lethal concentration in laboratory bioassays, indicating that such mixtures may have the potential for application in the field. This has led to the motivation to investigate further interactions between CrleGV-SA in combination with CrpeNPV, CpGV-M, and HearNPV-Au to understand better how these viruses interact and to determine whether synergistic, additive, or antagonistic interactions can occur against T. leucotreta. The outcome of these interactions will inform researchers and farmers about best practices concerning these viruses should they be combined against T. leucotreta in the future. Prior to performing mixed baculovirus infections in laboratory bioassays, oligonucleotides targeting unique regions in the viral genomes of CrleGV-SA, CrpeNPV, CpGV-M, and HearNPV-Au were designed using Primer-BLAST. The specificity of these oligonucleotides was further tested in silico using Geneious R11 software (11.1.5). The stocks of CrpeNPV, CpGV-M, and HearNPV-Au were purified using crude OB extraction from diseased C. peltastica, C. pomonella, and H. armigera larval cadavers provided by River Bioscience (Pty) Ltd (Gqeberha, South Africa). The stock of CrleGV-SA was purified using crude OB extraction from infected T. leucotreta cadavers. Subsequently, the unique oligonucleotides were used in PCR assays to detect if the samples contained the baculoviruses of interest. Amplicons of the expected sizes were generated indicating the presence of CrleGV-SA, CrpeNPV, CpGV-M, and HearNPV-Au in each of the samples. The OBs were counted using darkfield microscopy and a counting chamber before the single and mixed infections were initiated against T. leucotreta neonate larvae. Surface-dose biological assays were used to evaluate the relative virulence in terms of lethal concentration of CrleGV-SA, CrpeNPV, and CpGV-M, alone against T. leucotreta. After 7 days, the dose mortality data was analysed using “drc” in R studio and the LC50 and LC90 were compared amongst each virus. The CrleGV-SA treatment was estimated to be the most virulent in comparison to CrpeNPV and CpGV-M. A dose discriminate assay confirmed that HearNPV does not cause mortality in T. leucotreta. Similarly, the relative virulence in terms of lethal concentration of CrleGV-SA in various ratios in combination with CrpeNPV, CpGV-M, and HearNPV-Au was determined using 7-day surface dose biological assays. The CrleGV/CrpeNPV was the most virulent mixture with lower LC50 and LC90 values measured in comparison to CrleGV/CpGV and CrleGV/HearNPV, respectively. The Tammes Bakuniak graphic method confirmed the CrleGV/CrpeNPV, CrleGV/CpGV, and CrleGV/HearNPV mixtures to be antagonistic against T. leucotreta neonate larvae in terms of lethal concentration. The last aspect of the study was to determine the probable cause of larval death. A modified CTAB protocol was used to extract genomic DNA from neonate-sized T. leucotreta cadavers collected in single and mixed infection assays. The gDNA served as templates in PCR assays using the unique oligonucleotides. In single infections, the presence of CrleGV-SA in CrpeNPV and HearNPV inoculated larvae was observed. The results suggest possible covert infections of CrleGV-SA in the T. leucotreta colony which may be caused by virus infection or an unknown stress factor. The results from the mixed infections showed the presence of each virus in all replicates except for the CrleGV/CpGV and CrleGV/HearNPV mixtures. In the CrleGV/CpGV mixture, only CrleGV-SA was present in the last replicate, suggesting a possible competition for host resources. In the CrleGV/HearNPV mixture, only CrleGV-SA was detected in all 3 replicates, suggesting that HearNPV did not have any effect and the larvae died of the CrleGV-SA infection. This is the first study to report mixtures of CrleGV-SA in combination with CpGV-M and HearNPV-Au against T. leucotreta neonate larvae. Despite the antagonistic interactions observed in the evaluated mixtures, this study has laid a foundation to further investigate how these viruses interact in dual infections for the improved control of T. leucotreta. This may be done by evaluating different ratios and combinations of baculoviruses to those used in this study. , Thesis (MSc) -- Faculty of Science, Biochemistry, Microbiology & Bioinformatics, 2024
- Full Text:
- Date Issued: 2024-10-11
- Authors: Tole, Siviwe
- Date: 2024-10-11
- Subjects: False codling moth Biological control , Baculoviruses , Integrated pest management , Natural pesticides , Granulovirus
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/463996 , vital:76464
- Description: False codling moth (FCM), Thaumatotibia leucotreta, is an important pest of citrus, stone fruit, avocados, peppers, and other important agricultural crops in southern Africa. Baculovirus-based biopesticides are components in an integrated pest management (IPM) programme to manage the pest in the field. Cryptogran™ and Cryptex™ which are CrleGV-SA based-biopesticides have been effective in the control of T. leucotreta for the past 15 years. Recently, CrpeNPV-based Multimax™ and Codlmax™ have been commercialised to control T. leucotreta and other important agricultural pests. Despite these viruses being relatively host-specific and safe to humans and animals in comparison to chemical insecticides, their application is hindered by their slow speed of kill, sensitivity to UV light, and the potential for insect resistance. Research investigating the effects of mixed baculoviral interactions against target pests has been a growing field of interest due to their potential to overcome such shortcomings. Previous studies using a combination of CrleGV-SA and CrpeNPV against T. leucotreta observed a reduction in lethal concentration in laboratory bioassays, indicating that such mixtures may have the potential for application in the field. This has led to the motivation to investigate further interactions between CrleGV-SA in combination with CrpeNPV, CpGV-M, and HearNPV-Au to understand better how these viruses interact and to determine whether synergistic, additive, or antagonistic interactions can occur against T. leucotreta. The outcome of these interactions will inform researchers and farmers about best practices concerning these viruses should they be combined against T. leucotreta in the future. Prior to performing mixed baculovirus infections in laboratory bioassays, oligonucleotides targeting unique regions in the viral genomes of CrleGV-SA, CrpeNPV, CpGV-M, and HearNPV-Au were designed using Primer-BLAST. The specificity of these oligonucleotides was further tested in silico using Geneious R11 software (11.1.5). The stocks of CrpeNPV, CpGV-M, and HearNPV-Au were purified using crude OB extraction from diseased C. peltastica, C. pomonella, and H. armigera larval cadavers provided by River Bioscience (Pty) Ltd (Gqeberha, South Africa). The stock of CrleGV-SA was purified using crude OB extraction from infected T. leucotreta cadavers. Subsequently, the unique oligonucleotides were used in PCR assays to detect if the samples contained the baculoviruses of interest. Amplicons of the expected sizes were generated indicating the presence of CrleGV-SA, CrpeNPV, CpGV-M, and HearNPV-Au in each of the samples. The OBs were counted using darkfield microscopy and a counting chamber before the single and mixed infections were initiated against T. leucotreta neonate larvae. Surface-dose biological assays were used to evaluate the relative virulence in terms of lethal concentration of CrleGV-SA, CrpeNPV, and CpGV-M, alone against T. leucotreta. After 7 days, the dose mortality data was analysed using “drc” in R studio and the LC50 and LC90 were compared amongst each virus. The CrleGV-SA treatment was estimated to be the most virulent in comparison to CrpeNPV and CpGV-M. A dose discriminate assay confirmed that HearNPV does not cause mortality in T. leucotreta. Similarly, the relative virulence in terms of lethal concentration of CrleGV-SA in various ratios in combination with CrpeNPV, CpGV-M, and HearNPV-Au was determined using 7-day surface dose biological assays. The CrleGV/CrpeNPV was the most virulent mixture with lower LC50 and LC90 values measured in comparison to CrleGV/CpGV and CrleGV/HearNPV, respectively. The Tammes Bakuniak graphic method confirmed the CrleGV/CrpeNPV, CrleGV/CpGV, and CrleGV/HearNPV mixtures to be antagonistic against T. leucotreta neonate larvae in terms of lethal concentration. The last aspect of the study was to determine the probable cause of larval death. A modified CTAB protocol was used to extract genomic DNA from neonate-sized T. leucotreta cadavers collected in single and mixed infection assays. The gDNA served as templates in PCR assays using the unique oligonucleotides. In single infections, the presence of CrleGV-SA in CrpeNPV and HearNPV inoculated larvae was observed. The results suggest possible covert infections of CrleGV-SA in the T. leucotreta colony which may be caused by virus infection or an unknown stress factor. The results from the mixed infections showed the presence of each virus in all replicates except for the CrleGV/CpGV and CrleGV/HearNPV mixtures. In the CrleGV/CpGV mixture, only CrleGV-SA was present in the last replicate, suggesting a possible competition for host resources. In the CrleGV/HearNPV mixture, only CrleGV-SA was detected in all 3 replicates, suggesting that HearNPV did not have any effect and the larvae died of the CrleGV-SA infection. This is the first study to report mixtures of CrleGV-SA in combination with CpGV-M and HearNPV-Au against T. leucotreta neonate larvae. Despite the antagonistic interactions observed in the evaluated mixtures, this study has laid a foundation to further investigate how these viruses interact in dual infections for the improved control of T. leucotreta. This may be done by evaluating different ratios and combinations of baculoviruses to those used in this study. , Thesis (MSc) -- Faculty of Science, Biochemistry, Microbiology & Bioinformatics, 2024
- Full Text:
- Date Issued: 2024-10-11