Carbonylation of cyclohexene with carbon dioxide (CO2) using transition metals as heterogeneous and homogeneous catalysts
- Authors: Sekaleli, Bafokeng Thabelo
- Date: 2024-10-11
- Subjects: Carbonylation , Carbon dioxide , Catalysts , Transition metals , Cyclohexene
- 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: Carbonylation , Carbon dioxide , Catalysts , Transition metals , Cyclohexene
- 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
Double jeopardy: reflections of accessing and navigating public spaces during COVID-19 by blind and visually impaired (BVI) people in Gqeberha
- Authors: Sysaar, Nicay Courtlynn
- Date: 2024-10-11
- Subjects: People with visual disabilities South Africa , Blind South Africa , COVID-19 Pandemic, 2020-2023 Influence , Barrier-free design , Epidemics Social aspects , Blind Social conditions
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/466306 , vital:76716
- Description: Disability only exists in reference to ability, denoting that people are only disabled if considered and treated as disabled. The inherent social conditions and features of society significantly shape disability. The impact of the COVID-19 pandemic was significant in the lives of blind and visually impaired individuals (BVI) since these individuals “access the world” through tactile contact, a behaviour strongly opposed during the pandemic. Therefore, this study explored how BVI individuals struggled to access and navigate public spaces in Gqeberha and how their risk of contracting COVID-19 increased when accessing these spaces. The study was qualitative ethnographic research. It was conducted in Gqeberha and embedded within a non-governmental organisation (NGO). A heterogeneous purposive sampling method was used to recruit ten BVI individuals and four trainers. Data was generated through semi-structured interviews and participant observation and analysed thematically. The study's key findings demonstrate that the COVID-19 countermeasures implicated the lives of BVI individuals, as some felt the need to avoid public spaces not by choice but by obligation to protect themselves from the possible risk of infection. The research findings reveal the barriers encountered through social encounters, physical navigation of the built environment, and information access, thus making the social, digital, and physical spheres inaccessible. COVID-19 exacerbated these barriers while simultaneously revealing the perpetual debilitating barriers in the lives of BVI people before the pandemic, during the pandemic, and presently. The recommendations explored the implementation of awareness-based programmes, integration and inclusion in physical spheres, and inclusionary disaster communication during disasters. Ultimately, as a society, we have a lot to do to achieve accessibility and, fundamentally, social integration. It is recommended that when developing health safety policies in times of crisis, it is crucial to consider populations with unique challenges rather than having a blasé approach. , Thesis (MSocSci) -- Faculty of Humanities, Anthropology, 2024
- Full Text:
- Date Issued: 2024-10-11
- Authors: Sysaar, Nicay Courtlynn
- Date: 2024-10-11
- Subjects: People with visual disabilities South Africa , Blind South Africa , COVID-19 Pandemic, 2020-2023 Influence , Barrier-free design , Epidemics Social aspects , Blind Social conditions
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/466306 , vital:76716
- Description: Disability only exists in reference to ability, denoting that people are only disabled if considered and treated as disabled. The inherent social conditions and features of society significantly shape disability. The impact of the COVID-19 pandemic was significant in the lives of blind and visually impaired individuals (BVI) since these individuals “access the world” through tactile contact, a behaviour strongly opposed during the pandemic. Therefore, this study explored how BVI individuals struggled to access and navigate public spaces in Gqeberha and how their risk of contracting COVID-19 increased when accessing these spaces. The study was qualitative ethnographic research. It was conducted in Gqeberha and embedded within a non-governmental organisation (NGO). A heterogeneous purposive sampling method was used to recruit ten BVI individuals and four trainers. Data was generated through semi-structured interviews and participant observation and analysed thematically. The study's key findings demonstrate that the COVID-19 countermeasures implicated the lives of BVI individuals, as some felt the need to avoid public spaces not by choice but by obligation to protect themselves from the possible risk of infection. The research findings reveal the barriers encountered through social encounters, physical navigation of the built environment, and information access, thus making the social, digital, and physical spheres inaccessible. COVID-19 exacerbated these barriers while simultaneously revealing the perpetual debilitating barriers in the lives of BVI people before the pandemic, during the pandemic, and presently. The recommendations explored the implementation of awareness-based programmes, integration and inclusion in physical spheres, and inclusionary disaster communication during disasters. Ultimately, as a society, we have a lot to do to achieve accessibility and, fundamentally, social integration. It is recommended that when developing health safety policies in times of crisis, it is crucial to consider populations with unique challenges rather than having a blasé approach. , Thesis (MSocSci) -- Faculty of Humanities, Anthropology, 2024
- Full Text:
- Date Issued: 2024-10-11
Examining the direct and indirect effect that individual and contextual risk factors have in predicting substance abuse
- Authors: Fouten, Elron Steve
- Date: 2024-10-11
- Subjects: Structural equation modeling , Substance abuse South Africa , Ecological Systems Theory , Path analysis (Statistics) , Personality , Confirmatory factor analysis
- Language: English
- Type: Academic theses , Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/467006 , vital:76806 , DOI https://doi.org/10.21504/10962/467006
- Description: Substance abuse levels in South Africa have continued to rise, with the age of first experimentation with drugs reported as being 10 years. Several studies have shown that substance abuse has an adverse impact on users, their families and their communities, resulting in a number of social, psychological and economic struggles. Moreover, substance abuse places an increased psychological, social and financial burden on the individual and the family, as it has been related to the destabilisation of the nuclear and extended family units, permeating every area of life and affecting the very social fabric of society. This study therefore endeavoured to determine which of the individual and contextual risk factors measured by the South African Substance Use Contextual Risk Instrument (SASUCRI) best predicts substance abuse in a sample of self-identified substance abusers. Additionally, the study sought to determine the magnitude, strength and direction of the interaction of the individual and contextual risk factors in predicting substance abuse. The specific aims of the study were: 1) to build a theoretical model that best approximates the identified and measured individual and contextual factors associated with substance abuse, 2) to use structural equation modelling (SEM) to test the adequacy of the model’s fit to the data that have been collected, 3) to use SEM to statistically determine which of the perceived individual or contextual factors best predict substance abuse, and 4) to use SEM to statistically determine which combination of perceived individual and contextual factors best predict substance abuse. To achieve these aims, the study applied SEM to data collected from individuals seeking either inpatient or outpatient treatment for substance abuse in the Eastern Cape and Western Cape Provinces of South Africa, respectively. The purpose of SEM is to a priori specify a theoretical causal model consisting of a set of predicted covariances between variables, and then test whether it is plausible when compared to the observed data. The appropriateness of performing SEM exists in its ability and suitability to examine the nature and magnitude of postulated dependence relationships, while simultaneously assessing the direct and indirect relations of the variables. The theoretical causal model that was tested contained latent and manifest variables that were identified as risk factors for substance abuse. The causal model was informed by Bronfenbrenner’s (1977a, 1986) ecological systems theory (EST) and was specified to approximate the different systems of the theory. Data for the study were collected using the relatively newly developed and validated SASUCRI. The results of the confirmatory factor analysis (CFA) showed that the SASUCRI was a reliable and valid instrument to use with this population, and that the results of the structural model can be interpreted with confidence. The fit statistics, for the normal theory and related bootstrap latent path SEM, all indicate that the model is an excellent fit to the data CMIN/DF = 2.82, NFI = .946, CFI = .97, RMSEA = .04., thus achieving the study’s objective. The normal theory analysis of the paths in the diagram identified the microsystem, “Access/proximity to drugs” (APTD) and “Concerns for future” (CFF) as significant predictors of substance abuse, whereas the bootstrap analysis of the paths identified the macrosystem, APTD and CFF as significant predictors of substance abuse. This study identified 10 risk profiles that interact in the prediction of substance abuse; these are: individuals with low self-efficacy (SE) who perceive their family as lacking or having low intra-family communication, who lack positive peer support, who perceive criminal behaviours as normal, who feel a strong need to fit in, who are less religious, who have easy access to drugs, who lack a sense of community traditions and belonging, who see public displays of substance use (SU) as normal, and who lack concern for the future, are at 59% greater risk of substance abuse. Though micro level factors (low SE, lack of or low intra-family communication, and a lack of positive peer support) and meso-level factors (normalisation of criminal activity, a strong need to fit in, and being less religious) does not significantly predict abuse, they significantly interact with external factors in predicting substance abuse. Thus, it is only when they interact with factors located in the other systems (exosystem, macrosystem and chronosystem) that they become significant predictors of substance abuse. Conversely, exosystem (easy access to drugs), macrosystem (lack of a sense of community traditions and belonging, commonplace public displays of SU), and chronosystem factors (lack of concern for the future), independently are significant predictors of substance abuse. These findings carry significant public health implications by challenging the prevailing focus on individual-based interventions. Recognising that the drivers of substance abuse extend beyond individual factors, this study therefore advocates for interventions that address the broader systems contributing to the issue. This has the potential to inform more effective and holistic public health strategies. Finally, this study emphasises the need for comprehensive strategies that span different systems, acknowledging the role of family, community and societal factors. This call for complex interventions aligns with the ecological systems perspective, advocating for a paradigm shift in how we address SU by considering the broader environmental influences that contribute to the problem. In summary, this study not only contributes to the academic understanding of SU, but also has practical implications for public health policies and interventions. , Thesis (PhD) -- Faculty of Humanities, Psychology, 2024
- Full Text:
- Date Issued: 2024-10-11
- Authors: Fouten, Elron Steve
- Date: 2024-10-11
- Subjects: Structural equation modeling , Substance abuse South Africa , Ecological Systems Theory , Path analysis (Statistics) , Personality , Confirmatory factor analysis
- Language: English
- Type: Academic theses , Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/467006 , vital:76806 , DOI https://doi.org/10.21504/10962/467006
- Description: Substance abuse levels in South Africa have continued to rise, with the age of first experimentation with drugs reported as being 10 years. Several studies have shown that substance abuse has an adverse impact on users, their families and their communities, resulting in a number of social, psychological and economic struggles. Moreover, substance abuse places an increased psychological, social and financial burden on the individual and the family, as it has been related to the destabilisation of the nuclear and extended family units, permeating every area of life and affecting the very social fabric of society. This study therefore endeavoured to determine which of the individual and contextual risk factors measured by the South African Substance Use Contextual Risk Instrument (SASUCRI) best predicts substance abuse in a sample of self-identified substance abusers. Additionally, the study sought to determine the magnitude, strength and direction of the interaction of the individual and contextual risk factors in predicting substance abuse. The specific aims of the study were: 1) to build a theoretical model that best approximates the identified and measured individual and contextual factors associated with substance abuse, 2) to use structural equation modelling (SEM) to test the adequacy of the model’s fit to the data that have been collected, 3) to use SEM to statistically determine which of the perceived individual or contextual factors best predict substance abuse, and 4) to use SEM to statistically determine which combination of perceived individual and contextual factors best predict substance abuse. To achieve these aims, the study applied SEM to data collected from individuals seeking either inpatient or outpatient treatment for substance abuse in the Eastern Cape and Western Cape Provinces of South Africa, respectively. The purpose of SEM is to a priori specify a theoretical causal model consisting of a set of predicted covariances between variables, and then test whether it is plausible when compared to the observed data. The appropriateness of performing SEM exists in its ability and suitability to examine the nature and magnitude of postulated dependence relationships, while simultaneously assessing the direct and indirect relations of the variables. The theoretical causal model that was tested contained latent and manifest variables that were identified as risk factors for substance abuse. The causal model was informed by Bronfenbrenner’s (1977a, 1986) ecological systems theory (EST) and was specified to approximate the different systems of the theory. Data for the study were collected using the relatively newly developed and validated SASUCRI. The results of the confirmatory factor analysis (CFA) showed that the SASUCRI was a reliable and valid instrument to use with this population, and that the results of the structural model can be interpreted with confidence. The fit statistics, for the normal theory and related bootstrap latent path SEM, all indicate that the model is an excellent fit to the data CMIN/DF = 2.82, NFI = .946, CFI = .97, RMSEA = .04., thus achieving the study’s objective. The normal theory analysis of the paths in the diagram identified the microsystem, “Access/proximity to drugs” (APTD) and “Concerns for future” (CFF) as significant predictors of substance abuse, whereas the bootstrap analysis of the paths identified the macrosystem, APTD and CFF as significant predictors of substance abuse. This study identified 10 risk profiles that interact in the prediction of substance abuse; these are: individuals with low self-efficacy (SE) who perceive their family as lacking or having low intra-family communication, who lack positive peer support, who perceive criminal behaviours as normal, who feel a strong need to fit in, who are less religious, who have easy access to drugs, who lack a sense of community traditions and belonging, who see public displays of substance use (SU) as normal, and who lack concern for the future, are at 59% greater risk of substance abuse. Though micro level factors (low SE, lack of or low intra-family communication, and a lack of positive peer support) and meso-level factors (normalisation of criminal activity, a strong need to fit in, and being less religious) does not significantly predict abuse, they significantly interact with external factors in predicting substance abuse. Thus, it is only when they interact with factors located in the other systems (exosystem, macrosystem and chronosystem) that they become significant predictors of substance abuse. Conversely, exosystem (easy access to drugs), macrosystem (lack of a sense of community traditions and belonging, commonplace public displays of SU), and chronosystem factors (lack of concern for the future), independently are significant predictors of substance abuse. These findings carry significant public health implications by challenging the prevailing focus on individual-based interventions. Recognising that the drivers of substance abuse extend beyond individual factors, this study therefore advocates for interventions that address the broader systems contributing to the issue. This has the potential to inform more effective and holistic public health strategies. Finally, this study emphasises the need for comprehensive strategies that span different systems, acknowledging the role of family, community and societal factors. This call for complex interventions aligns with the ecological systems perspective, advocating for a paradigm shift in how we address SU by considering the broader environmental influences that contribute to the problem. In summary, this study not only contributes to the academic understanding of SU, but also has practical implications for public health policies and interventions. , Thesis (PhD) -- Faculty of Humanities, Psychology, 2024
- Full Text:
- Date Issued: 2024-10-11
Experimental and theoretical studies in the elucidation of chemical and biochemical reaction mechanisms
- Authors: Mafokwana, Kamogelo
- Date: 2024-10-11
- Subjects: Uncatalogued
- Language: English
- Type: Academic theses , Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/466592 , vital:76757
- Description: Access restricted. Exected release in 2026. , Thesis (PhD) -- Faculty of Science, Chemistry, 2024
- Full Text:
- Date Issued: 2024-10-11
- Authors: Mafokwana, Kamogelo
- Date: 2024-10-11
- Subjects: Uncatalogued
- Language: English
- Type: Academic theses , Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/466592 , vital:76757
- Description: Access restricted. Exected release in 2026. , Thesis (PhD) -- Faculty of Science, Chemistry, 2024
- Full Text:
- Date Issued: 2024-10-11
Realist evaluation cases of the uptake and use of citizen science tools for water quality management: Vaal-Triangle public primary schools teachers and Mpophomeni enviro-champs
- Authors: Madiba, Morakane Stephinah
- Date: 2024-10-11
- Subjects: Realist evaluation , Citizen science , Water quality management South Africa Vaal Triangle , Social learning , Voluntarism , Ubuntu (Philosophy)
- Language: English
- Type: Academic theses , Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/466406 , vital:76725 , DOI https://doi.org/10.21504/10962/466406
- Description: This study employs a theory-based approach to evaluate citizen science (CS) interventions in two distinct cases: the Mpophomeni enviro-champs and the Vaal-Triangle primary school teachers. These interventions were designed to foster social learning, enhance education or participants' understanding of water quality impacts, and promote community or public participation for improved water management. GroundTruth, a multidisciplinary consulting company with expertise in water resources and environmental engineering, collaborated as partners in these CS projects. Utilizing qualitative realist evaluation theory, the study delves into the intricate context-mechanismoutcome (CMO) configurations for each case, seeking depth insight into the outcomes of these citizen science initiatives. Data collection involved interviews, document analysis, and participant observations to construct a comprehensive understanding of the interventions' impact. In the case of the Vaal-Triangle primary school teachers, the CS intervention yielded positive results, significantly influencing teaching practices and instilling shared values for sustainable water quality management in both classrooms and the surrounding communities. However, the study revealed the need for continued evaluation and comprehensive dialogue among stakeholders, including teachers, school governing bodies, local municipalities, the Department of Basic Education, and the broader community to ensure the effectiveness, sustainability, and transformative potential of these interventions. In contrast, the Mpophomeni enviro-champs experienced a different set of outcomes. The CS intervention catalyzed numerous opportunities for the volunteers, forging a collaborative relationship between citizens and the government. Despite their socio-ecological vulnerability, these volunteers exhibited remarkable resilience and willingness to contribute, calling for formalization mechanisms such as remuneration and skill recognition to sustain and enhance their participation. This study provides insights into citizen science interventions, foregrounding volunteerism as a means of fostering fair and inclusive participation. It emphasizes the significance of combining social and classroom learning in achieving sustainable water quality management objectives. Furthermore, the research highlights the pivotal role of informed citizenship, which necessitates an understanding not only of environmental activism but also of effective political engagement to influence decision-making processes effectively. By challenging historical barriers and revealing new perspectives, this study offers a reflective thinking tool to advance transformative policy development in South Africa and beyond, promoting informed and responsible public participation in water quality management and fostering the sustainability of precious water resources. , Thesis (PhD) -- Faculty of Education, Secondary and Post-School Education, 2024
- Full Text:
- Date Issued: 2024-10-11
- Authors: Madiba, Morakane Stephinah
- Date: 2024-10-11
- Subjects: Realist evaluation , Citizen science , Water quality management South Africa Vaal Triangle , Social learning , Voluntarism , Ubuntu (Philosophy)
- Language: English
- Type: Academic theses , Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/466406 , vital:76725 , DOI https://doi.org/10.21504/10962/466406
- Description: This study employs a theory-based approach to evaluate citizen science (CS) interventions in two distinct cases: the Mpophomeni enviro-champs and the Vaal-Triangle primary school teachers. These interventions were designed to foster social learning, enhance education or participants' understanding of water quality impacts, and promote community or public participation for improved water management. GroundTruth, a multidisciplinary consulting company with expertise in water resources and environmental engineering, collaborated as partners in these CS projects. Utilizing qualitative realist evaluation theory, the study delves into the intricate context-mechanismoutcome (CMO) configurations for each case, seeking depth insight into the outcomes of these citizen science initiatives. Data collection involved interviews, document analysis, and participant observations to construct a comprehensive understanding of the interventions' impact. In the case of the Vaal-Triangle primary school teachers, the CS intervention yielded positive results, significantly influencing teaching practices and instilling shared values for sustainable water quality management in both classrooms and the surrounding communities. However, the study revealed the need for continued evaluation and comprehensive dialogue among stakeholders, including teachers, school governing bodies, local municipalities, the Department of Basic Education, and the broader community to ensure the effectiveness, sustainability, and transformative potential of these interventions. In contrast, the Mpophomeni enviro-champs experienced a different set of outcomes. The CS intervention catalyzed numerous opportunities for the volunteers, forging a collaborative relationship between citizens and the government. Despite their socio-ecological vulnerability, these volunteers exhibited remarkable resilience and willingness to contribute, calling for formalization mechanisms such as remuneration and skill recognition to sustain and enhance their participation. This study provides insights into citizen science interventions, foregrounding volunteerism as a means of fostering fair and inclusive participation. It emphasizes the significance of combining social and classroom learning in achieving sustainable water quality management objectives. Furthermore, the research highlights the pivotal role of informed citizenship, which necessitates an understanding not only of environmental activism but also of effective political engagement to influence decision-making processes effectively. By challenging historical barriers and revealing new perspectives, this study offers a reflective thinking tool to advance transformative policy development in South Africa and beyond, promoting informed and responsible public participation in water quality management and fostering the sustainability of precious water resources. , Thesis (PhD) -- Faculty of Education, Secondary and Post-School Education, 2024
- Full Text:
- Date Issued: 2024-10-11
Selective and sensitive electrochemical detection of the Human Epidermal Growth Receptor 2 breast cancer biomarker, using Co (II) phthalocyanine-nanoparticle based platforms
- Centane, Sixolile Sibongiseni
- Authors: Centane, Sixolile Sibongiseni
- Date: 2024-10-11
- Subjects: Electrochemical sensors , HER-2 protein , Breast Cancer , Biochemical markers , Phthalocyanines , Nanoparticles
- Language: English
- Type: Academic theses , Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/466569 , vital:76753 , DOI https://doi.org/10.21504/10962/466570
- Description: Breast cancer is the world’s leading cause of cancer related deaths in women worldwide. The main reason lies in its late detection, mostly in the metastatic stage resulting in poor after-therapy prognosis, despite advances in methods of diagnosis and therapy. The reason for late-stage detection, is because breast cancer like any other cancers is asymptomatic in its early stages. Significant and characterizable features present in the later stages. Furthermore, conventional methods for breast cancer detection are more useful in the identification of the phenotypic features of cancer cells that arise at a later stage of the disease. Another issue with conventional methods where cancer diagnosis is concerned is that they tend to be specialist-dependent, time consuming and costly. Thus, easy, fast and inexpensive detection methods need to be developed urgently. Biomarker-based cancer diagnosis has emerged as one of the most promising strategies for early diagnosis, monitoring disease progression, and subsequent cancer treatment. This thesis focuses on the design and development of novel electrochemical biosensor platforms towards the low cost, efficient, sensitive and simple detection of early-stage breast cancer biomarker, human epidermal growth factor 2 (HER2). The electrochemical method is preferred because of its moderate cost, rapid response, ease of operation, readily quantifiable signal as well as high sensitivity and selectivity with lower detection limits. This thesis reports on two strategies towards signal amplification and sensitive detection of HER2, namely signal based amplification and target-based amplification. The former focuses on electrode or transducer modification techniques for improved signal to noise ratio. In which case; novel nanocomposites of phthalocyanines, graphene quantum dots, gold nanoparticles and cerium oxide nanoparticles are used for electrode modification for signal amplification and biorecognition element immobilization. The biorecognition elements of choice, are an aptamer and antibody known to be specific to the HER2 antigen for an enhanced sensor sensitivity and specificity. The second strategy focuses on increasing the number of detectable targets on the electrode surface towards enhanced sensitivity, precision and sensor accuracy. In which case; the performance of the aptamer and the antibody as recognition elements was explored. Furthermore, the effect of arrangement of these recognition elements on the electrode surface is investigated and reported upon. The strategies covered in this thesis are expected to result in novel biosensor platforms that can detect the HER2 biomarker with high precision, reproducibility, sensitivity and stability; towards low cost and effective early-stage breast cancer diagnostic tools. , Thesis (PhD) -- Faculty of Science, Chemistry, 2024
- Full Text:
- Date Issued: 2024-10-11
- Authors: Centane, Sixolile Sibongiseni
- Date: 2024-10-11
- Subjects: Electrochemical sensors , HER-2 protein , Breast Cancer , Biochemical markers , Phthalocyanines , Nanoparticles
- Language: English
- Type: Academic theses , Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/466569 , vital:76753 , DOI https://doi.org/10.21504/10962/466570
- Description: Breast cancer is the world’s leading cause of cancer related deaths in women worldwide. The main reason lies in its late detection, mostly in the metastatic stage resulting in poor after-therapy prognosis, despite advances in methods of diagnosis and therapy. The reason for late-stage detection, is because breast cancer like any other cancers is asymptomatic in its early stages. Significant and characterizable features present in the later stages. Furthermore, conventional methods for breast cancer detection are more useful in the identification of the phenotypic features of cancer cells that arise at a later stage of the disease. Another issue with conventional methods where cancer diagnosis is concerned is that they tend to be specialist-dependent, time consuming and costly. Thus, easy, fast and inexpensive detection methods need to be developed urgently. Biomarker-based cancer diagnosis has emerged as one of the most promising strategies for early diagnosis, monitoring disease progression, and subsequent cancer treatment. This thesis focuses on the design and development of novel electrochemical biosensor platforms towards the low cost, efficient, sensitive and simple detection of early-stage breast cancer biomarker, human epidermal growth factor 2 (HER2). The electrochemical method is preferred because of its moderate cost, rapid response, ease of operation, readily quantifiable signal as well as high sensitivity and selectivity with lower detection limits. This thesis reports on two strategies towards signal amplification and sensitive detection of HER2, namely signal based amplification and target-based amplification. The former focuses on electrode or transducer modification techniques for improved signal to noise ratio. In which case; novel nanocomposites of phthalocyanines, graphene quantum dots, gold nanoparticles and cerium oxide nanoparticles are used for electrode modification for signal amplification and biorecognition element immobilization. The biorecognition elements of choice, are an aptamer and antibody known to be specific to the HER2 antigen for an enhanced sensor sensitivity and specificity. The second strategy focuses on increasing the number of detectable targets on the electrode surface towards enhanced sensitivity, precision and sensor accuracy. In which case; the performance of the aptamer and the antibody as recognition elements was explored. Furthermore, the effect of arrangement of these recognition elements on the electrode surface is investigated and reported upon. The strategies covered in this thesis are expected to result in novel biosensor platforms that can detect the HER2 biomarker with high precision, reproducibility, sensitivity and stability; towards low cost and effective early-stage breast cancer diagnostic tools. , Thesis (PhD) -- Faculty of Science, Chemistry, 2024
- Full Text:
- Date Issued: 2024-10-11
SolarKAT: a solar imaging pipeline for MeerKAT
- Samboco, Victória da Graça Gilberto
- Authors: Samboco, Victória da Graça Gilberto
- Date: 2024-10-11
- Subjects: MeerKAT , Radio interferometers , Solar activity , Radio Interference , Data processing
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/465102 , vital:76573
- Description: Solar interference poses a significant challenge in radio interferometric observations, particularly with the increasing sensitivity of modern new-generation telescopes. This thesis presents the SolarKAT pipeline, a novel approach designed to mitigate solar interference in MeerKAT observations. The pipeline incorporates a series of steps, including self-calibration (second generation calibration or 2GC), precise determination of the Sun’s position, phase centre adjustments, creation of region-based masks, deconvolution, prediction, solar model subtraction, and peeling. We applied the SolarKAT pipeline to three datasets that feature the Sun in different conditions (frequency band and angular distance from the Sun to the telescope pointing position). These observations were obtained from three MeerKAT telescope surveys: ThunderKAT, MIGHTEE and LADUMA. We compared the visual images, peak fluxes, flux density, RMS and pixel distribution to evaluate the pipeline. Our results showed a notable reduction in solar interference. This is evidenced by the improved image quality, reduction in RMS and pixel distribution values, and consistent peak flux measurements after applying the pipeline. SolarKAT has not only improved the data quality but also demonstrated to be a valuable tool in producing high-quality solar images, which can be a helpful resource for solar physics and space weather forecasts. This study showcases the potential of the SolarKAT pipeline in enabling high-quality radio interferometric observations, even in the presence of solar interference. Unlike conventional methods that often discard corrupted visibilities (e.g. flagging), our approach focuses on recovering them. Additionally, the SolarKAT pipeline naturally delivers detailed images of the Sun. Our findings contribute to advancing the field of radio interferometry, providing a valuable tool for researchers seeking to enhance the accuracy of their observations and conduct studies in solar physics and space weather. , Thesis (MSc) -- Faculty of Science, Physics and Electronics, 2024
- Full Text:
- Date Issued: 2024-10-11
- Authors: Samboco, Victória da Graça Gilberto
- Date: 2024-10-11
- Subjects: MeerKAT , Radio interferometers , Solar activity , Radio Interference , Data processing
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/465102 , vital:76573
- Description: Solar interference poses a significant challenge in radio interferometric observations, particularly with the increasing sensitivity of modern new-generation telescopes. This thesis presents the SolarKAT pipeline, a novel approach designed to mitigate solar interference in MeerKAT observations. The pipeline incorporates a series of steps, including self-calibration (second generation calibration or 2GC), precise determination of the Sun’s position, phase centre adjustments, creation of region-based masks, deconvolution, prediction, solar model subtraction, and peeling. We applied the SolarKAT pipeline to three datasets that feature the Sun in different conditions (frequency band and angular distance from the Sun to the telescope pointing position). These observations were obtained from three MeerKAT telescope surveys: ThunderKAT, MIGHTEE and LADUMA. We compared the visual images, peak fluxes, flux density, RMS and pixel distribution to evaluate the pipeline. Our results showed a notable reduction in solar interference. This is evidenced by the improved image quality, reduction in RMS and pixel distribution values, and consistent peak flux measurements after applying the pipeline. SolarKAT has not only improved the data quality but also demonstrated to be a valuable tool in producing high-quality solar images, which can be a helpful resource for solar physics and space weather forecasts. This study showcases the potential of the SolarKAT pipeline in enabling high-quality radio interferometric observations, even in the presence of solar interference. Unlike conventional methods that often discard corrupted visibilities (e.g. flagging), our approach focuses on recovering them. Additionally, the SolarKAT pipeline naturally delivers detailed images of the Sun. Our findings contribute to advancing the field of radio interferometry, providing a valuable tool for researchers seeking to enhance the accuracy of their observations and conduct studies in solar physics and space weather. , Thesis (MSc) -- Faculty of Science, Physics and Electronics, 2024
- Full Text:
- Date Issued: 2024-10-11
Teachers’ use of authentic tasks through mathematics trails in a mobile learning environment to facilitate conceptual teaching
- Authors: Matengu, Given Kahale
- Date: 2024-10-11
- Subjects: Authenticity (Philosophy) , Mobile communication systems in education , Mathematics Study and teaching (Secondary) Namibia , Math walk , Mathematics Study and teaching Activity programs , Educational technology Namibia
- Language: English
- Type: Academic theses , Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/466429 , vital:76727 , DOI https://doi.org/10.21504/10962/466429
- Description: The teaching and learning of mathematics in Namibia is confronted by various forms of challenges that require continuous search for effective pedagogical strategies and approaches to enhance mathematical understanding. Some of the ways include using real and authentic outdoor activities and technological tools, such as smartphones, for teaching and learning purposes. The need to use authentic and realistic tasks in outdoor settings in the teaching of mathematics has strong support from the literature. Moreover, many recent reforms in education challenge teachers across all subjects to use modern and up-to-date technologies to complement and support existing approaches to teaching. Smartphones, in particular, offer new opportunities in the evolution of technology-enhanced learning by allowing teaching and learning to occur in authentic and realistic contexts that extend to real-life environments. This qualitative case study proposes a practical framework that can facilitate mathematical understanding in teaching through the implementation of authentic and realistic outdoor tasks by using the Math City Map (MCM) project on a smartphone. The study aims to analyse and understand how mathematics teachers can create and implement authentic and realistic tasks in an outdoor mathematics trail to facilitate the conceptual teaching of area, volume, ratio and proportion topics, within the context of the Realistic Mathematics Education theory (RME). The study is framed within the RME theory and the iPAC (personalisation, authenticity, collaboration) mobile pedagogical framework. The research process is underpinned by an interpretivist paradigm. Data was collected from eight selected teachers through observations and interviews and analysed using frameworks derived from the RME and iPAC mobile pedagogical theories and the emergence of common themes. The findings suggest that the integration of smartphones and mathematics trails have pedagogical benefits in mathematics teaching and can facilitate the use of outdoor tasks that are connected to learners’ realities. The study argues that while MCM mathematics trail tasks can be difficult to create, it was worthwhile for teachers using them to conceptually teach the selected topics. It is therefore hoped that the findings of this study contribute towards the use of outdoor mathematics trails and smartphones in the teaching of mathematics. , Thesis (PhD) -- Faculty of Education, Secondary and Post-School Education, 2024
- Full Text:
- Date Issued: 2024-10-11
- Authors: Matengu, Given Kahale
- Date: 2024-10-11
- Subjects: Authenticity (Philosophy) , Mobile communication systems in education , Mathematics Study and teaching (Secondary) Namibia , Math walk , Mathematics Study and teaching Activity programs , Educational technology Namibia
- Language: English
- Type: Academic theses , Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/466429 , vital:76727 , DOI https://doi.org/10.21504/10962/466429
- Description: The teaching and learning of mathematics in Namibia is confronted by various forms of challenges that require continuous search for effective pedagogical strategies and approaches to enhance mathematical understanding. Some of the ways include using real and authentic outdoor activities and technological tools, such as smartphones, for teaching and learning purposes. The need to use authentic and realistic tasks in outdoor settings in the teaching of mathematics has strong support from the literature. Moreover, many recent reforms in education challenge teachers across all subjects to use modern and up-to-date technologies to complement and support existing approaches to teaching. Smartphones, in particular, offer new opportunities in the evolution of technology-enhanced learning by allowing teaching and learning to occur in authentic and realistic contexts that extend to real-life environments. This qualitative case study proposes a practical framework that can facilitate mathematical understanding in teaching through the implementation of authentic and realistic outdoor tasks by using the Math City Map (MCM) project on a smartphone. The study aims to analyse and understand how mathematics teachers can create and implement authentic and realistic tasks in an outdoor mathematics trail to facilitate the conceptual teaching of area, volume, ratio and proportion topics, within the context of the Realistic Mathematics Education theory (RME). The study is framed within the RME theory and the iPAC (personalisation, authenticity, collaboration) mobile pedagogical framework. The research process is underpinned by an interpretivist paradigm. Data was collected from eight selected teachers through observations and interviews and analysed using frameworks derived from the RME and iPAC mobile pedagogical theories and the emergence of common themes. The findings suggest that the integration of smartphones and mathematics trails have pedagogical benefits in mathematics teaching and can facilitate the use of outdoor tasks that are connected to learners’ realities. The study argues that while MCM mathematics trail tasks can be difficult to create, it was worthwhile for teachers using them to conceptually teach the selected topics. It is therefore hoped that the findings of this study contribute towards the use of outdoor mathematics trails and smartphones in the teaching of mathematics. , Thesis (PhD) -- Faculty of Education, Secondary and Post-School Education, 2024
- Full Text:
- Date Issued: 2024-10-11
The effect of biological control on the population dynamics of Pontederia crassipes Mart. (Pontederiaceae) and Salvinia minima Baker (Salviniales: Salviniaceae)
- Authors: Chikodza, Tressia
- Date: 2024-10-11
- Subjects: Pontederia crassipes , Salvinia minima , Pontederiaceae Biological control South Africa , Salviniaceae Biological control South Africa , Population dynamics , Secondary invasion
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/464462 , vital:76513
- Description: Pontederia crassipes is widely regarded as the most damaging floating aquatic weed in terms of its invasive traits, and its impact on aquatic ecosystems. Biological control using host-specific natural enemies is widely used for its control, with the most recent agent released being a planthopper, Megamelus scutellaris, in South Africa and the USA. In South Africa, inundative releases of M. scutellaris have been shown to control the weed even at eutrophic, and high elevation cold sites, such as Hartbeespoort Dam, arguably Africa’s most hypertrophic impoundment. However, subsequent to the control of P. crassipes on Hartbeespoort Dam, in 2021, a secondary invader, Salvinia minima, dominated the water system. Salvinia minima is only known from a handful sites near Hartbeespoort Dam and there is currently no approved biocontrol agent for it. The population dynamics of P. crassipes and S. minima at the Dam were overall interchanging due to insect feeding on M. scutellaris reducing P. crassipes populations thus allowing S. minima to become dominant. Intense feeding from M. scutellaris resulted in the reduction of P. crassipes populations. During late autumn and winter, remaining P. crassipes plants experienced frost damage from cold temperatures. The decrease in P. crassipes allowed S. minima to successfully invade, potentially as the result of less competition from P. crassipes, and therefore available resources, such as space, nutrients, and light. However, as spring approached, P. crassipes regenerated from its seed bank, and S. minima populations diminished. The changes in dominance were observed in 2021 and 2022 but in 2023, this trend was not evident as S. minima did not dominate as in previous years. This thesis investigated the combination of competition and herbivory by M. scutellaris on the vigour of P. crassipes and S. minima to understand the dynamics of these two highly invasive species. Competitive abilities of P. crassipes and S. minima were determined using an inverse linear model with plant weight as the yield variable. In the absence of herbivory, P. crassipes, was 4 times more competitive than S. minima, but as competitive when exposed to M. scutellaris feeding. Salvinia minima was 1.2 times as aggressive as P. crassipes in the absence of herbivory, but 2.6 times as competitive when M. scutellaris was established on P. crassipes. In the presence of herbivory on P. crassipes, interspecific competition coefficients from P. crassipes on S. minima were no longer statistically significant. These results indicate that the competitive ability of P. crassipes was reduced through herbivory when grown with S. minima, explaining the temporal dominance between the two species at Hartbeespoort Dam. Some studies have reported that P. crassipes releases allelochemicals as a competitive strategy to algae and phytoplankton. Previously identified allelochemicals include N-phenyl-1-naphthylamine, N-phenyl-2-naphthylamine and linoleic acid. This thesis investigated the presence or absence of key chemical compounds released by P. crassipes during allelopathy with microbes and phytoplankton to determine its potential to inhibit S. minima growth. Methanol extracts from P. crassipes roots, leaves, and field samples underwent LC-ESI-MS/MS analysis, creating a molecular network to match chemical profiles. Of the investigated compounds, N-phenyl-1-naphthylamine and N-phenyl-2-naphthylamine were absent in P. crassipes and field samples, while linoleic acid was consistently found. Its presence suggests its potential defensive role against S. minima. Future research should explore allelochemical production in the presence of S. minima and algae to confirm if S. minima elicits an allelochemical response by P. crassipes, or whether the methods used here were insufficient to detect allelochemical production. Understanding whether P. crassipes employs allelochemicals, especially in the presence of S. minima, could shed light on its competitive advantage beyond its invasive nature at the Dam. , Thesis (MSc) -- Faculty of Science, Botany, 2024
- Full Text:
- Date Issued: 2024-10-11
- Authors: Chikodza, Tressia
- Date: 2024-10-11
- Subjects: Pontederia crassipes , Salvinia minima , Pontederiaceae Biological control South Africa , Salviniaceae Biological control South Africa , Population dynamics , Secondary invasion
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/464462 , vital:76513
- Description: Pontederia crassipes is widely regarded as the most damaging floating aquatic weed in terms of its invasive traits, and its impact on aquatic ecosystems. Biological control using host-specific natural enemies is widely used for its control, with the most recent agent released being a planthopper, Megamelus scutellaris, in South Africa and the USA. In South Africa, inundative releases of M. scutellaris have been shown to control the weed even at eutrophic, and high elevation cold sites, such as Hartbeespoort Dam, arguably Africa’s most hypertrophic impoundment. However, subsequent to the control of P. crassipes on Hartbeespoort Dam, in 2021, a secondary invader, Salvinia minima, dominated the water system. Salvinia minima is only known from a handful sites near Hartbeespoort Dam and there is currently no approved biocontrol agent for it. The population dynamics of P. crassipes and S. minima at the Dam were overall interchanging due to insect feeding on M. scutellaris reducing P. crassipes populations thus allowing S. minima to become dominant. Intense feeding from M. scutellaris resulted in the reduction of P. crassipes populations. During late autumn and winter, remaining P. crassipes plants experienced frost damage from cold temperatures. The decrease in P. crassipes allowed S. minima to successfully invade, potentially as the result of less competition from P. crassipes, and therefore available resources, such as space, nutrients, and light. However, as spring approached, P. crassipes regenerated from its seed bank, and S. minima populations diminished. The changes in dominance were observed in 2021 and 2022 but in 2023, this trend was not evident as S. minima did not dominate as in previous years. This thesis investigated the combination of competition and herbivory by M. scutellaris on the vigour of P. crassipes and S. minima to understand the dynamics of these two highly invasive species. Competitive abilities of P. crassipes and S. minima were determined using an inverse linear model with plant weight as the yield variable. In the absence of herbivory, P. crassipes, was 4 times more competitive than S. minima, but as competitive when exposed to M. scutellaris feeding. Salvinia minima was 1.2 times as aggressive as P. crassipes in the absence of herbivory, but 2.6 times as competitive when M. scutellaris was established on P. crassipes. In the presence of herbivory on P. crassipes, interspecific competition coefficients from P. crassipes on S. minima were no longer statistically significant. These results indicate that the competitive ability of P. crassipes was reduced through herbivory when grown with S. minima, explaining the temporal dominance between the two species at Hartbeespoort Dam. Some studies have reported that P. crassipes releases allelochemicals as a competitive strategy to algae and phytoplankton. Previously identified allelochemicals include N-phenyl-1-naphthylamine, N-phenyl-2-naphthylamine and linoleic acid. This thesis investigated the presence or absence of key chemical compounds released by P. crassipes during allelopathy with microbes and phytoplankton to determine its potential to inhibit S. minima growth. Methanol extracts from P. crassipes roots, leaves, and field samples underwent LC-ESI-MS/MS analysis, creating a molecular network to match chemical profiles. Of the investigated compounds, N-phenyl-1-naphthylamine and N-phenyl-2-naphthylamine were absent in P. crassipes and field samples, while linoleic acid was consistently found. Its presence suggests its potential defensive role against S. minima. Future research should explore allelochemical production in the presence of S. minima and algae to confirm if S. minima elicits an allelochemical response by P. crassipes, or whether the methods used here were insufficient to detect allelochemical production. Understanding whether P. crassipes employs allelochemicals, especially in the presence of S. minima, could shed light on its competitive advantage beyond its invasive nature at the Dam. , Thesis (MSc) -- Faculty of Science, Botany, 2024
- Full Text:
- Date Issued: 2024-10-11
The impact of international investment agreements on FDI in developing countries and the implications for development policy
- Authors: Lomas, Djamella
- Date: 2024-10-11
- Subjects: Investments, Foreign , Bilateral Investment Treaty , Gravity model of international trade , Developing countries Foreign economic relations , Developing countries Economic policy , BRIC countries
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/463489 , vital:76413
- Description: This study investigates the impact of international investment agreements, specifically bilateral investment treaties (BITs), on inward Foreign direct investment (FDI) in recipient developing countries and the implications of such agreements for development policy. The study estimates a log-linear gravity model based on a unique dataset created to investigate whether the presence of BITs has a positive impact on inward FDI stock in 36 developing countries. The selection of countries attempts to capture a set of bilateral relationships that accounts for a significant proportion of inward FDI in developing countries. To test the hypothesis that signing BITs has a positive effect on inward FDI in developing countries it was necessary that all recipient countries be developing economies. However, investor countries are both developed and developing economies. Therefore, each bilateral FDI relationship is either between a developing recipient and developed investor country or between a developing recipient and developing investor country. For each recipient country, FDI stock data from investor countries for 2019 was obtained from the ITC’s Investment Map database (ITC, 2022). This yielded 1009 bilateral FDI relationships (observations for the dependent variable) after removing pairs for which certain explanatory variable data was not available. For the gravity model, GDP data was collected from the World Bank’s World Development Indicators Database (World Bank, 2023a), while the other traditional gravity variables were collected from the CEPII GeoDist Database (CEPII, 2011). Alongside the gravity variables, the study employs three additional control variables (two macroeconomic and one institutional) in certain specifications of the basic model, namely the exchange rate, inflation rate and an index of political stability. Data for the three additional variables was sourced from the IMF’s World Economic Outlook Database (IMF, 2022) for the macroeconomic variables and the World Bank’s Worldwide Governance Indicators Database (World Bank, 2023b) in the case of the political stability index. To examine the key question of the impact of BITs on bilateral FDI, a number of BITs dummy variables are created to investigate, firstly, whether having signed a BIT impacts on FDI in developing countries and, secondly, whether having a BIT in force significantly impacts on FDI in developing countries. Thereafter, in each case, dummy variables are created to investigate whether there is a significant difference between the impact on FDI of having a BIT signed or in force between a developed and developing country specifically, and having a BIT signed or in force between two developing countries. In order to examine the implications for development policy, the thesis analyses case studies of selected BITs between developed and developing economies, as well as those between developing economies. The texts of the BIT documents were obtained from the UNCTAD Investment Policy Hub Database (UNCTAD, 2023b). The results of the study reveal that, on average, signing and/or having a BIT in force has a significant positive impact on the inward FDI stock of the recipient developing country from the outward investor country. This positive impact is found to be even stronger in the case of BITs between developed and developing countries. However, there is no significant impact on inward FDI for BITs signed between two developing countries. The study finds that GDP of the recipient and investor country, existence of a common official language and the distance between countries all have a significant impact on FDI in the recipient developing country, and are signed as expected in the gravity literature. The existence of a common border is weakly significant in some specifications of the basic model and not significant in others. The additional control variables are all significant and signed as expected in the literature. The study contributes to the literature by distinguishing, not only between the impact of BITs signed versus BITs in force on inward FDI in developing countries, but also by distinguishing between the impact of BITs on FDI when the partners are developed and developing countries versus when both partners are developing countries. The study also finds that, in an effort to attract FDI, developing countries have signed BITs which carry obligations that extend significant protection measures to foreign investors. However, such protections are offered at the expense of sovereign interests. The study finds that this has served to significantly reduce the policy space available for developing countries to attract FDI that is aligned to their sustainable development needs. The limitations of the study are as follows. The gravity specification is cross-sectional, and a panel data approach could be recommended for future work. Furthermore, the traditional OLS gravity specification has a number of disadvantages and different types of estimator could be used in future work, software permitting. In addition, the impact on FDI of the termination of BITs could be investigated, as sufficient data is becoming available for such an approach. Finally, it is difficult to generalise from the case study analysis undertaken of specific BITs provisions because of the limited number of BITs examined in the thesis. , Thesis (MCom) -- Faculty of Commerce, Economics and Economic History, 2024
- Full Text:
- Date Issued: 2024-10-11
- Authors: Lomas, Djamella
- Date: 2024-10-11
- Subjects: Investments, Foreign , Bilateral Investment Treaty , Gravity model of international trade , Developing countries Foreign economic relations , Developing countries Economic policy , BRIC countries
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/463489 , vital:76413
- Description: This study investigates the impact of international investment agreements, specifically bilateral investment treaties (BITs), on inward Foreign direct investment (FDI) in recipient developing countries and the implications of such agreements for development policy. The study estimates a log-linear gravity model based on a unique dataset created to investigate whether the presence of BITs has a positive impact on inward FDI stock in 36 developing countries. The selection of countries attempts to capture a set of bilateral relationships that accounts for a significant proportion of inward FDI in developing countries. To test the hypothesis that signing BITs has a positive effect on inward FDI in developing countries it was necessary that all recipient countries be developing economies. However, investor countries are both developed and developing economies. Therefore, each bilateral FDI relationship is either between a developing recipient and developed investor country or between a developing recipient and developing investor country. For each recipient country, FDI stock data from investor countries for 2019 was obtained from the ITC’s Investment Map database (ITC, 2022). This yielded 1009 bilateral FDI relationships (observations for the dependent variable) after removing pairs for which certain explanatory variable data was not available. For the gravity model, GDP data was collected from the World Bank’s World Development Indicators Database (World Bank, 2023a), while the other traditional gravity variables were collected from the CEPII GeoDist Database (CEPII, 2011). Alongside the gravity variables, the study employs three additional control variables (two macroeconomic and one institutional) in certain specifications of the basic model, namely the exchange rate, inflation rate and an index of political stability. Data for the three additional variables was sourced from the IMF’s World Economic Outlook Database (IMF, 2022) for the macroeconomic variables and the World Bank’s Worldwide Governance Indicators Database (World Bank, 2023b) in the case of the political stability index. To examine the key question of the impact of BITs on bilateral FDI, a number of BITs dummy variables are created to investigate, firstly, whether having signed a BIT impacts on FDI in developing countries and, secondly, whether having a BIT in force significantly impacts on FDI in developing countries. Thereafter, in each case, dummy variables are created to investigate whether there is a significant difference between the impact on FDI of having a BIT signed or in force between a developed and developing country specifically, and having a BIT signed or in force between two developing countries. In order to examine the implications for development policy, the thesis analyses case studies of selected BITs between developed and developing economies, as well as those between developing economies. The texts of the BIT documents were obtained from the UNCTAD Investment Policy Hub Database (UNCTAD, 2023b). The results of the study reveal that, on average, signing and/or having a BIT in force has a significant positive impact on the inward FDI stock of the recipient developing country from the outward investor country. This positive impact is found to be even stronger in the case of BITs between developed and developing countries. However, there is no significant impact on inward FDI for BITs signed between two developing countries. The study finds that GDP of the recipient and investor country, existence of a common official language and the distance between countries all have a significant impact on FDI in the recipient developing country, and are signed as expected in the gravity literature. The existence of a common border is weakly significant in some specifications of the basic model and not significant in others. The additional control variables are all significant and signed as expected in the literature. The study contributes to the literature by distinguishing, not only between the impact of BITs signed versus BITs in force on inward FDI in developing countries, but also by distinguishing between the impact of BITs on FDI when the partners are developed and developing countries versus when both partners are developing countries. The study also finds that, in an effort to attract FDI, developing countries have signed BITs which carry obligations that extend significant protection measures to foreign investors. However, such protections are offered at the expense of sovereign interests. The study finds that this has served to significantly reduce the policy space available for developing countries to attract FDI that is aligned to their sustainable development needs. The limitations of the study are as follows. The gravity specification is cross-sectional, and a panel data approach could be recommended for future work. Furthermore, the traditional OLS gravity specification has a number of disadvantages and different types of estimator could be used in future work, software permitting. In addition, the impact on FDI of the termination of BITs could be investigated, as sufficient data is becoming available for such an approach. Finally, it is difficult to generalise from the case study analysis undertaken of specific BITs provisions because of the limited number of BITs examined in the thesis. , Thesis (MCom) -- Faculty of Commerce, Economics and Economic History, 2024
- Full Text:
- Date Issued: 2024-10-11
The investigation of novel Benzimidazoles as anti-cancer agents in triple negative breast cancer cell lines
- Authors: Smit, Christie Jane
- Date: 2024-10-11
- Subjects: Uncatalogued
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/463973 , vital:76462
- Description: Access restricted. Exxpected release in 2026. , Thesis (MSc) -- Faculty of Science, Biochemistry, Microbiology & Bioinformatics, 2024
- Full Text:
- Date Issued: 2024-10-11
- Authors: Smit, Christie Jane
- Date: 2024-10-11
- Subjects: Uncatalogued
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/463973 , vital:76462
- Description: Access restricted. Exxpected release in 2026. , Thesis (MSc) -- Faculty of Science, Biochemistry, Microbiology & Bioinformatics, 2024
- Full Text:
- Date Issued: 2024-10-11
The role of students in internal quality assurance: a case study of Namibian institutions of higher education
- Authors: Nghikembua, Anneli Ndapanda
- Date: 2024-10-11
- Subjects: Quality assurance , Education, Higher Evaluation , Universities and colleges Accreditation Namibia , Universities and colleges Auditing , Student participation in administration
- Language: English
- Type: Academic theses , Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/466395 , vital:76724 , DOI htps://doi.org/10.21504/10962/466395
- Description: The interplay of the mechanisms such as globalisation, massification and internationalisation led to higher education systems across the world introducing quality assurance. As systems have massified, student bodies have diversified with the result that the quality of teaching and learning has become increasingly important and has drawn the attention of policy makers and researchers. The Namibian higher education system was no different in heeding the call to develop quality assurance systems. As this happened, calls to involve students in quality assurance because of their roles as “stakeholders” in higher education were also heeded, and in common with institutions in systems across the world, those in Namibia began to include students in governance and quality assurance. Research on student involvement in internal quality assurance with a focus on higher education institutions in Namibia is scarce. This study aims to fill this gap by examining the role of students as stakeholders in the quality of teaching and learning in higher education institutions in three Namibian institutions. Roy Bhaskar’s (1978; 1989) critical realism and Margaret Archer’s (1995; 1996; 2000) social realism were used to build a theoretical framework which allowed for the exploration of students’ involvement in the quality assurance of teaching and learning. Critical and social realism both draw on the idea of a “depth ontology” and acknowledge that what is available to researchers empirically is only part of reality. As a result, critical and social realist researchers aim to move from empirical data to explore a level of reality not directly accessible via the senses. In the study underpinning this thesis, this involved using inference to move from interview data and documents to explore a level of reality from which events and experiences of events (both accessible empirically) emerge. A case study approach was used involving a “cross case” analysis of the three institutions. Questions guiding the study aimed not only to explore ways in which students were, or were not involved, in assuring quality of their education, but also what constrained and enabled involvement. Ultimately the study focused on whether or not their engagement contributed to the enhancement of quality. As all the institutions in the study did allow students to be involved in quality assurance, the question was the extent to which this involvement was “meaningful” in the sense that it could lead to change. Insights derived from the study showed that although students were represented on various governance structures, their experiences were that their contributions to debates and the issues they raised were not heeded. Another significant way in which students were involved in quality assurance was through the provision of feedback on teaching and course design. The investigation showed that, although teaching and learning centres at the three institutions studied did use feedback from students to develop training programmes for academic teachers, feedback was mainly used for instrumental purposes such as personal promotion, an observation which raises questions about the extent to which its elicitation could lead to enhancement. The use of Archer’s social realism allowed for the identification of a number of constraints on the potential of student involvement to contribute to the enhancement of teaching and learning. One such constraint was the hierarchical nature of institutional organisations which led to student comments not always being treated seriously, sometimes because of perceptions of their “immaturity”. Another constraint was related to confused understandings of what constitutes “quality” in policy documents. The study recommends that policies and manuals on student involvement should be designed to provide guidance to staff and students on how they should be involved. There is also a need to train students on their involvement as well as interrogate the student involvement beliefs and practices. , Thesis (PhD) -- Faculty of Education, Centre for Higher Education Research, Teaching and Learning, 2024
- Full Text:
- Date Issued: 2024-10-11
- Authors: Nghikembua, Anneli Ndapanda
- Date: 2024-10-11
- Subjects: Quality assurance , Education, Higher Evaluation , Universities and colleges Accreditation Namibia , Universities and colleges Auditing , Student participation in administration
- Language: English
- Type: Academic theses , Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/466395 , vital:76724 , DOI htps://doi.org/10.21504/10962/466395
- Description: The interplay of the mechanisms such as globalisation, massification and internationalisation led to higher education systems across the world introducing quality assurance. As systems have massified, student bodies have diversified with the result that the quality of teaching and learning has become increasingly important and has drawn the attention of policy makers and researchers. The Namibian higher education system was no different in heeding the call to develop quality assurance systems. As this happened, calls to involve students in quality assurance because of their roles as “stakeholders” in higher education were also heeded, and in common with institutions in systems across the world, those in Namibia began to include students in governance and quality assurance. Research on student involvement in internal quality assurance with a focus on higher education institutions in Namibia is scarce. This study aims to fill this gap by examining the role of students as stakeholders in the quality of teaching and learning in higher education institutions in three Namibian institutions. Roy Bhaskar’s (1978; 1989) critical realism and Margaret Archer’s (1995; 1996; 2000) social realism were used to build a theoretical framework which allowed for the exploration of students’ involvement in the quality assurance of teaching and learning. Critical and social realism both draw on the idea of a “depth ontology” and acknowledge that what is available to researchers empirically is only part of reality. As a result, critical and social realist researchers aim to move from empirical data to explore a level of reality not directly accessible via the senses. In the study underpinning this thesis, this involved using inference to move from interview data and documents to explore a level of reality from which events and experiences of events (both accessible empirically) emerge. A case study approach was used involving a “cross case” analysis of the three institutions. Questions guiding the study aimed not only to explore ways in which students were, or were not involved, in assuring quality of their education, but also what constrained and enabled involvement. Ultimately the study focused on whether or not their engagement contributed to the enhancement of quality. As all the institutions in the study did allow students to be involved in quality assurance, the question was the extent to which this involvement was “meaningful” in the sense that it could lead to change. Insights derived from the study showed that although students were represented on various governance structures, their experiences were that their contributions to debates and the issues they raised were not heeded. Another significant way in which students were involved in quality assurance was through the provision of feedback on teaching and course design. The investigation showed that, although teaching and learning centres at the three institutions studied did use feedback from students to develop training programmes for academic teachers, feedback was mainly used for instrumental purposes such as personal promotion, an observation which raises questions about the extent to which its elicitation could lead to enhancement. The use of Archer’s social realism allowed for the identification of a number of constraints on the potential of student involvement to contribute to the enhancement of teaching and learning. One such constraint was the hierarchical nature of institutional organisations which led to student comments not always being treated seriously, sometimes because of perceptions of their “immaturity”. Another constraint was related to confused understandings of what constitutes “quality” in policy documents. The study recommends that policies and manuals on student involvement should be designed to provide guidance to staff and students on how they should be involved. There is also a need to train students on their involvement as well as interrogate the student involvement beliefs and practices. , Thesis (PhD) -- Faculty of Education, Centre for Higher Education Research, Teaching and Learning, 2024
- Full Text:
- Date Issued: 2024-10-11
The significance of neglected themes in the visual representation of Ulwaluko
- Authors: Nqweniso, Sinazo
- Date: 2024-10-11
- Subjects: Ulwaluko , Circumcision South Africa , Traditional knowledge , Ethnoscience South Africa , Ceremonial objects , Rites and ceremonies South Africa
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/466060 , vital:76681
- Description: This study investigates the significance of the neglected themes in visual representations of the Xhosa (also AmaXhosa) ritual of manhood called ulwaluko. The focus is on attire, cosmetics, language, food, games and music. These themes are part of the various components that constitute ulwaluko as a complex and significant practice amongst the Xhosa people, which comprises layered meanings, activities, and procedures involved in the ritual transformation of males from boyhood to manhood. The neglected themes are imperative in the education and socialisation of Xhosa men, and the formation of their identity and pride. Through ulwaluko, Xhosa men gain significant knowledge about maturity, cultured demeanour, marriage, family, human rights, and domestic and substance abuse. These teachings are essential in educating, shaping and moulding Xhosa men. Throughout the three decades from the 1990s to the 2020s, ulwaluko has suffered a crisis evidenced by injuries and deaths of initiates through careless procedures of circumcision, irresponsible nursing of the initiates and unfavourable conditions where the education of initiates takes place. This crisis has been a burning subject not only for journalists and scholars but also artists and filmmakers. The crisis dominates visual representations of ulwaluko in South African contemporary art. This study argues that even amid fatalities such as pain, injuries and the death of initiates, ulwaluko is still an essential institution that contributes to social practices and the moral fibre of society. Using Afrocentrism and the indigenous knowledge system as theoretical lenses, this study appreciates ulwaluko culture by interpreting researched data from an African-centred perspective. This approach produces African knowledge that recognises the African voice and affirms the centrality of cultural experience. The use of indigenous knowledge is to access the neglected themes in popular knowledge and culture by appreciating the Xhosa ways of knowing, being and understanding in contemporary African society. , Thesis (MA) -- Faculty of Humanities, Fine Art, 2024
- Full Text:
- Date Issued: 2024-10-11
- Authors: Nqweniso, Sinazo
- Date: 2024-10-11
- Subjects: Ulwaluko , Circumcision South Africa , Traditional knowledge , Ethnoscience South Africa , Ceremonial objects , Rites and ceremonies South Africa
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/466060 , vital:76681
- Description: This study investigates the significance of the neglected themes in visual representations of the Xhosa (also AmaXhosa) ritual of manhood called ulwaluko. The focus is on attire, cosmetics, language, food, games and music. These themes are part of the various components that constitute ulwaluko as a complex and significant practice amongst the Xhosa people, which comprises layered meanings, activities, and procedures involved in the ritual transformation of males from boyhood to manhood. The neglected themes are imperative in the education and socialisation of Xhosa men, and the formation of their identity and pride. Through ulwaluko, Xhosa men gain significant knowledge about maturity, cultured demeanour, marriage, family, human rights, and domestic and substance abuse. These teachings are essential in educating, shaping and moulding Xhosa men. Throughout the three decades from the 1990s to the 2020s, ulwaluko has suffered a crisis evidenced by injuries and deaths of initiates through careless procedures of circumcision, irresponsible nursing of the initiates and unfavourable conditions where the education of initiates takes place. This crisis has been a burning subject not only for journalists and scholars but also artists and filmmakers. The crisis dominates visual representations of ulwaluko in South African contemporary art. This study argues that even amid fatalities such as pain, injuries and the death of initiates, ulwaluko is still an essential institution that contributes to social practices and the moral fibre of society. Using Afrocentrism and the indigenous knowledge system as theoretical lenses, this study appreciates ulwaluko culture by interpreting researched data from an African-centred perspective. This approach produces African knowledge that recognises the African voice and affirms the centrality of cultural experience. The use of indigenous knowledge is to access the neglected themes in popular knowledge and culture by appreciating the Xhosa ways of knowing, being and understanding in contemporary African society. , Thesis (MA) -- Faculty of Humanities, Fine Art, 2024
- Full Text:
- Date Issued: 2024-10-11
Towards a bacterial biofertiliser for the rehabilitation of disturbed and degraded land
- Authors: Masudi, Wiya Leon
- Date: 2024-10-11
- Subjects: Biofertilizers , Land degradation , Ecological disturbances , Plant-growth promoting rhizobacteria , Restoration ecology
- Language: English
- Type: Academic theses , Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/466826 , vital:76790 , DOI https://doi.org/10.21504/10962/466826
- Description: Agriculture, mining, industry, and human activity disturb, degrade, and pollute pristine environments and particularly the soil environment. Excessive land exploitation slows or disrupts the soil potential, rendering it incapable of playing its role leading to land degradation. In the mining sector, specifically coal mining, rehabilitation of disturbed and degraded land involves strategies that include importing topsoil and using fossil fuel-derived fertilisers. Both practices are unsustainable. To address the unsustainability, a myco-phytoremediation technology known as Fungcoal was developed to facilitate successful revegetation of mining-disturbed and degraded land following the bioconversion of waste coal into a soil-like humic-rich substrate. To offset the dependence on chemical-based fertilisers, efforts were/are focussed on finding mutualistic and cost-effective microbial resources with plant growth-promoting (PGP) activity as a bacterial biofertiliser. This study made use of 22 isolated bacteria and the three Fungcoal coal-degrading fungi viz., Aspergillus sp. ECCN 84, Aspergillus sp. ECCN 225 and Penicillium sp. ECCN 243 as the microbial resource. Initially, characterisation of the substrate waste coal and molecular identification of the selected bacterial isolates were carried out. Physicochemical analysis of the low-rank coal (LRC) substrate revealed a pH of 3.60 with background S content equivalent to 7.13 g L-1, N at 20 mg L-1, P at 7.8 mg L-1 and K at 3.3 mg L-1. Energy-dispersive X-ray spectroscopy (EDX) analysis revealed a C and O content of 23.09 and 69.03 wt%, respectively. Metagenomic analysis of the microbial population associated with the LRC substrate showed that among the 96.32% of bacteria, 59.46 to 62.18% belonged to Bacillota (also called Firmicutes), a phylum of largely Gram-positive bacteria, and 33.01 to 35.74% to Pseudomonadota (synonymous with Proteobacteria), a phylum of mostly Gram-negative bacteria. Following purification of the selected bacterial isolates and molecular characterisation by PCR, phylogenetic relatedness to known plant growth-promoting bacteria (PGPB) contained in the GenBank database showed that these bacterial isolates clustered with high bootstrap values to the reference PGPB strains. Only Pseudomonas sp. ECCN 10b (MW672582) was outside of the tree and shared significant similarity (100%) with Pseudomonas fluorescens (CP015638). A biochemical study revealed that the two Proteus sp. strains, Exiguobacterium sp., Enterobacter sp., and Ancylobacter, tolerated high salt and a wide range of temperatures. Bacterial isolates showed a high pH tolerance between 3 and 11, with the best growth at pH around 7. Nine of the identified strains, four Bacillus sp., Exiguobacterium sp., Enterobacter sp., Pseudomonas sp., Arthrobacter sp., and Aeromonas sp., were able to grow and increase in a medium containing either glucose, mannitol, sodium L-glutamate, sucrose, or fructose. Growth was highest in media containing either sodium L-glutamate, sucrose, or fructose. All the coal degrading strains and 83% of those isolated from municipal wastewater used more complex carbon sources such as high and LRC. The potential for PGP activity was quantified spectrophotometrically by measuring the production of auxins, as indole-3-acetic acid (IAA) equivalents; gibberellins, as gibberellic acid (GA3) equivalents, along with 1-aminocyclopropane-1-carboxylic acid (ACC) deaminase and siderophore activity. Additionally, nutrient mobilisation was evaluated by monitoring an ability to mineralise NH4+, PO43−, and K+. Competent PGP strains for the coal degrading isolates included Proteus strain ECCN 20b, Proteus strain ECCN 23b, and Serratia strain ECCN 24b. In response to L-trp supplementation, the concentration of indolic compounds (measured as indole-3-acetic acid) increased. Production of ammonium and solubilisation of insoluble P by these strains was also apparent. Only Serratia strain ECCN 24b could solubilise insoluble K. Production of indoles increased following exposure to increasing aliquots of LRC, suggesting no negative effect of this material on indole production and that these bacteria may possess PGP potential. Of the twelve bacterial strains isolated from wastewater MaB-flocs, three produced indoles, nine mineralised NH4+, seven solubilised P, and one K. Potential of isolated strains for PGP activity according to a one-way ANOVA on ranks was: ECCN 7b > ECCN 4b > ECCN 6b > ECCN 3b = ECCN 10b > ECCN 1b = ECCN 5b > ECCN 8b > ECCN 2b > ECCN 12b > ECCN 9b = ECCN 11b. Further study revealed that cell-free filtrate from indole-producing cultures of Aeromonas strain ECCN 4b, Enterobacter strain ECCN 7b, and Arthrobacter strain ECCN 6b promoted mung bean adventitious root formation. Based on a biochemical study and the outcome of the ranking of bacterial strains according to PGP-like activities, three bacteria, Enterobacter sp., strain ECCN 7b, Proteus sp., strain ECCN 20b and Serratia sp., strain ECCN 24b that showed great mutualistic relationship with the most effective Fungcoal biocatalyst, A. fischeri ECCN 84, were used to prepare a bacterial bio-fertiliser. This consortium grew well in NB supplemented with L-tryptophan and produced indole compounds that could activate the adventitious rooting of mung bean (Vigna radiata L.) hypocotyls. Finally, the consortium showed no antibiotic resistance activity; however, they produced better biofertiliser with good responses to root/plant biomass production of the same Fabaceae, mung bean (Vigna radiata L.). The further development of this consortium into a cost-effective, environmentally friendly biofertiliser may help reduce dependence on chemical-based fertilisers and improve the sustainability of Fungcoal and other land rehabilitation strategies. Further studies are therefore underway to investigate in greater detail the PGP activity of these isolates individually and in consortium under field conditions to support the Fungcoal myco-phytoremediation strategy. , Thesis (PhD) -- Faculty of Science, Institute for Environmental Biotechnology, 2024
- Full Text:
- Date Issued: 2024-10-11
- Authors: Masudi, Wiya Leon
- Date: 2024-10-11
- Subjects: Biofertilizers , Land degradation , Ecological disturbances , Plant-growth promoting rhizobacteria , Restoration ecology
- Language: English
- Type: Academic theses , Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/466826 , vital:76790 , DOI https://doi.org/10.21504/10962/466826
- Description: Agriculture, mining, industry, and human activity disturb, degrade, and pollute pristine environments and particularly the soil environment. Excessive land exploitation slows or disrupts the soil potential, rendering it incapable of playing its role leading to land degradation. In the mining sector, specifically coal mining, rehabilitation of disturbed and degraded land involves strategies that include importing topsoil and using fossil fuel-derived fertilisers. Both practices are unsustainable. To address the unsustainability, a myco-phytoremediation technology known as Fungcoal was developed to facilitate successful revegetation of mining-disturbed and degraded land following the bioconversion of waste coal into a soil-like humic-rich substrate. To offset the dependence on chemical-based fertilisers, efforts were/are focussed on finding mutualistic and cost-effective microbial resources with plant growth-promoting (PGP) activity as a bacterial biofertiliser. This study made use of 22 isolated bacteria and the three Fungcoal coal-degrading fungi viz., Aspergillus sp. ECCN 84, Aspergillus sp. ECCN 225 and Penicillium sp. ECCN 243 as the microbial resource. Initially, characterisation of the substrate waste coal and molecular identification of the selected bacterial isolates were carried out. Physicochemical analysis of the low-rank coal (LRC) substrate revealed a pH of 3.60 with background S content equivalent to 7.13 g L-1, N at 20 mg L-1, P at 7.8 mg L-1 and K at 3.3 mg L-1. Energy-dispersive X-ray spectroscopy (EDX) analysis revealed a C and O content of 23.09 and 69.03 wt%, respectively. Metagenomic analysis of the microbial population associated with the LRC substrate showed that among the 96.32% of bacteria, 59.46 to 62.18% belonged to Bacillota (also called Firmicutes), a phylum of largely Gram-positive bacteria, and 33.01 to 35.74% to Pseudomonadota (synonymous with Proteobacteria), a phylum of mostly Gram-negative bacteria. Following purification of the selected bacterial isolates and molecular characterisation by PCR, phylogenetic relatedness to known plant growth-promoting bacteria (PGPB) contained in the GenBank database showed that these bacterial isolates clustered with high bootstrap values to the reference PGPB strains. Only Pseudomonas sp. ECCN 10b (MW672582) was outside of the tree and shared significant similarity (100%) with Pseudomonas fluorescens (CP015638). A biochemical study revealed that the two Proteus sp. strains, Exiguobacterium sp., Enterobacter sp., and Ancylobacter, tolerated high salt and a wide range of temperatures. Bacterial isolates showed a high pH tolerance between 3 and 11, with the best growth at pH around 7. Nine of the identified strains, four Bacillus sp., Exiguobacterium sp., Enterobacter sp., Pseudomonas sp., Arthrobacter sp., and Aeromonas sp., were able to grow and increase in a medium containing either glucose, mannitol, sodium L-glutamate, sucrose, or fructose. Growth was highest in media containing either sodium L-glutamate, sucrose, or fructose. All the coal degrading strains and 83% of those isolated from municipal wastewater used more complex carbon sources such as high and LRC. The potential for PGP activity was quantified spectrophotometrically by measuring the production of auxins, as indole-3-acetic acid (IAA) equivalents; gibberellins, as gibberellic acid (GA3) equivalents, along with 1-aminocyclopropane-1-carboxylic acid (ACC) deaminase and siderophore activity. Additionally, nutrient mobilisation was evaluated by monitoring an ability to mineralise NH4+, PO43−, and K+. Competent PGP strains for the coal degrading isolates included Proteus strain ECCN 20b, Proteus strain ECCN 23b, and Serratia strain ECCN 24b. In response to L-trp supplementation, the concentration of indolic compounds (measured as indole-3-acetic acid) increased. Production of ammonium and solubilisation of insoluble P by these strains was also apparent. Only Serratia strain ECCN 24b could solubilise insoluble K. Production of indoles increased following exposure to increasing aliquots of LRC, suggesting no negative effect of this material on indole production and that these bacteria may possess PGP potential. Of the twelve bacterial strains isolated from wastewater MaB-flocs, three produced indoles, nine mineralised NH4+, seven solubilised P, and one K. Potential of isolated strains for PGP activity according to a one-way ANOVA on ranks was: ECCN 7b > ECCN 4b > ECCN 6b > ECCN 3b = ECCN 10b > ECCN 1b = ECCN 5b > ECCN 8b > ECCN 2b > ECCN 12b > ECCN 9b = ECCN 11b. Further study revealed that cell-free filtrate from indole-producing cultures of Aeromonas strain ECCN 4b, Enterobacter strain ECCN 7b, and Arthrobacter strain ECCN 6b promoted mung bean adventitious root formation. Based on a biochemical study and the outcome of the ranking of bacterial strains according to PGP-like activities, three bacteria, Enterobacter sp., strain ECCN 7b, Proteus sp., strain ECCN 20b and Serratia sp., strain ECCN 24b that showed great mutualistic relationship with the most effective Fungcoal biocatalyst, A. fischeri ECCN 84, were used to prepare a bacterial bio-fertiliser. This consortium grew well in NB supplemented with L-tryptophan and produced indole compounds that could activate the adventitious rooting of mung bean (Vigna radiata L.) hypocotyls. Finally, the consortium showed no antibiotic resistance activity; however, they produced better biofertiliser with good responses to root/plant biomass production of the same Fabaceae, mung bean (Vigna radiata L.). The further development of this consortium into a cost-effective, environmentally friendly biofertiliser may help reduce dependence on chemical-based fertilisers and improve the sustainability of Fungcoal and other land rehabilitation strategies. Further studies are therefore underway to investigate in greater detail the PGP activity of these isolates individually and in consortium under field conditions to support the Fungcoal myco-phytoremediation strategy. , Thesis (PhD) -- Faculty of Science, Institute for Environmental Biotechnology, 2024
- Full Text:
- Date Issued: 2024-10-11
A multidisciplinary study to assess the ecology of the Cape sea urchin, Parechinus angulosus, and its emerging use as a bioindicator to monitor coastal resiliency
- Authors: Redelinghuys, Suzanne
- Date: 2024-04-05
- Subjects: Intertidal ecology , Parechinus angulosus , Sea urchins Morphology , Sea urchins Climatic factors , Phylogeography , Morphometrics , Microbiomes , Marine invertebrates
- Language: English
- Type: Academic theses , Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/435691 , vital:73179 , DOI 10.21504/10962/435692
- Description: The resilience of marine species in the face of unpredictable climate change stands as a paramount concern for the maintenance of ecological stability. Under such fluctuating conditions, it is critical to understand how organisms mitigate these effects in physiological, genetic, and morphological terms. To that end, this thesis focused on the Cape sea urchin, Parechinus angulosus, employing a multidisciplinary approach encompassing morphology, genomics, and gut microbial diversity to assess its potential as a bioindicator species and elucidate its adaptive strategies in response to varying environmental conditions along the South African coastline. This was achieved through studying their anatomy in order to link observed variation to prevailing local environmental conditions, aided by the species’ wide distribution range which allows insight into adaptations across broad geographic regions and ecological settings. The first empirical chapter, Chapter 3, focusing on eight key morphometric traits of test, Aristotle’s lantern and spines, revealed distinct variation in the Cape sea urchin's morphology between the east and west coasts of South Africa, suggesting the presence of some level of local adaptation to the prevailing environmental factors found on the east and west coasts of South Africa. This points to potential bioindicator capabilities of the species, reflecting adaptive divergence amidst contrasting environmental conditions. Further analysis is however necessary in order to isolate specific physiological trends that may be associated with these morphometric differences, thereby enhancing and tightening their ecological implications. The second experimental chapter, Chapter 4, delved into the genetic structure of the Cape urchin by investigating genome-wide diversity, the presence of cryptic population structure, and spatial patterns of genomic diversity. Moderate genomic differentiation was detected among populations along the eastern and western coasts of South Africa by outlier loci that may undergo natural selection, which could indicate local adaptation to environmental conditions. This pattern hints at adaptive differentiation and cryptic genetic structures within the Cape sea urchin populations and emphasises the species' potential adaptive responses to localised (in this case regional) environmental pressures. Assigning functional significance to these genetic variations will require a comprehensive annotated reference genome, a limitation acknowledged in the current study. Chapter 5 explored the gut microbial diversity and revealed significant compositional variations between the east and west coast populations of South Africa, confirming regional and inter-regional variation. This chapter also highlighted the essential biochemical pathways critical to the survival of the host which is crucial for assessing the health of the urchin host. Together, the functional content of the gut bacteria and microbial diversity showcases its potential as a bioindicator for coastal ecosystem health. Logistical challenges and confounding factors like host physiology will need to be fully considered for its effective application. Overall, the findings of this doctoral research suggest that the Cape sea urchin displays promising characteristics as a bioindicator species due to its morphological, genetic, and gut microbial variations in response to environmental differences, providing a diverse array of means in which urchins could be used as bioindicators, from their uses to assess water quality and detect pollution, to ecosystem health monitoring and biodiversity studies in which sea urchin abundance, distribution, and presence are monitored. Further research, integrating these multidisciplinary approaches is recommended to validate and refine its bioindicator potential. Additionally, the development of a comprehensive annotated reference genome is imperative to harness the species' genetic information effectively. This study underscores the significance of integrating multiple disciplines in understanding how species respond to environmental change and their potentials contributions to monitor ecological resilience. The original multidisciplinary approach, combined with high computational outputs presents a promising framework for a comprehensive ecological monitoring in marine ecosystems. , Thesis (PhD) -- Faculty of Science, Zoology and Entomology, 2024
- Full Text:
- Date Issued: 2024-04-05
- Authors: Redelinghuys, Suzanne
- Date: 2024-04-05
- Subjects: Intertidal ecology , Parechinus angulosus , Sea urchins Morphology , Sea urchins Climatic factors , Phylogeography , Morphometrics , Microbiomes , Marine invertebrates
- Language: English
- Type: Academic theses , Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/435691 , vital:73179 , DOI 10.21504/10962/435692
- Description: The resilience of marine species in the face of unpredictable climate change stands as a paramount concern for the maintenance of ecological stability. Under such fluctuating conditions, it is critical to understand how organisms mitigate these effects in physiological, genetic, and morphological terms. To that end, this thesis focused on the Cape sea urchin, Parechinus angulosus, employing a multidisciplinary approach encompassing morphology, genomics, and gut microbial diversity to assess its potential as a bioindicator species and elucidate its adaptive strategies in response to varying environmental conditions along the South African coastline. This was achieved through studying their anatomy in order to link observed variation to prevailing local environmental conditions, aided by the species’ wide distribution range which allows insight into adaptations across broad geographic regions and ecological settings. The first empirical chapter, Chapter 3, focusing on eight key morphometric traits of test, Aristotle’s lantern and spines, revealed distinct variation in the Cape sea urchin's morphology between the east and west coasts of South Africa, suggesting the presence of some level of local adaptation to the prevailing environmental factors found on the east and west coasts of South Africa. This points to potential bioindicator capabilities of the species, reflecting adaptive divergence amidst contrasting environmental conditions. Further analysis is however necessary in order to isolate specific physiological trends that may be associated with these morphometric differences, thereby enhancing and tightening their ecological implications. The second experimental chapter, Chapter 4, delved into the genetic structure of the Cape urchin by investigating genome-wide diversity, the presence of cryptic population structure, and spatial patterns of genomic diversity. Moderate genomic differentiation was detected among populations along the eastern and western coasts of South Africa by outlier loci that may undergo natural selection, which could indicate local adaptation to environmental conditions. This pattern hints at adaptive differentiation and cryptic genetic structures within the Cape sea urchin populations and emphasises the species' potential adaptive responses to localised (in this case regional) environmental pressures. Assigning functional significance to these genetic variations will require a comprehensive annotated reference genome, a limitation acknowledged in the current study. Chapter 5 explored the gut microbial diversity and revealed significant compositional variations between the east and west coast populations of South Africa, confirming regional and inter-regional variation. This chapter also highlighted the essential biochemical pathways critical to the survival of the host which is crucial for assessing the health of the urchin host. Together, the functional content of the gut bacteria and microbial diversity showcases its potential as a bioindicator for coastal ecosystem health. Logistical challenges and confounding factors like host physiology will need to be fully considered for its effective application. Overall, the findings of this doctoral research suggest that the Cape sea urchin displays promising characteristics as a bioindicator species due to its morphological, genetic, and gut microbial variations in response to environmental differences, providing a diverse array of means in which urchins could be used as bioindicators, from their uses to assess water quality and detect pollution, to ecosystem health monitoring and biodiversity studies in which sea urchin abundance, distribution, and presence are monitored. Further research, integrating these multidisciplinary approaches is recommended to validate and refine its bioindicator potential. Additionally, the development of a comprehensive annotated reference genome is imperative to harness the species' genetic information effectively. This study underscores the significance of integrating multiple disciplines in understanding how species respond to environmental change and their potentials contributions to monitor ecological resilience. The original multidisciplinary approach, combined with high computational outputs presents a promising framework for a comprehensive ecological monitoring in marine ecosystems. , Thesis (PhD) -- Faculty of Science, Zoology and Entomology, 2024
- Full Text:
- Date Issued: 2024-04-05
Augmentation of Aphytis melinus DeBach (Hymenoptera: Aphelinidae) for the control of California red scale Aonidiella aurantii Maskell (Hemiptera: Diaspididae) on citrus
- De Beer, Ernst Friedrich Ludwig
- Authors: De Beer, Ernst Friedrich Ludwig
- Date: 2024-04-05
- Subjects: Aphytis melinus , Aphytis , Aonidiella aurantii , Citrus Diseases and pests South Africa , Pests Biological control
- Language: English
- Type: Academic theses , Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/435638 , vital:73175 , DOI 10.21504/10962/435638
- Description: Aphytis lingnanensis was reared and tested in South Africa in the early 2000s for augmentation against red scale on citrus and was found to be ineffective. Aphytis melinus is now commercially available and it is important that the efficacy of augmentation thereof on red scale is determined locally. Field trials, fitness assessments and molecular identification on A. melinus from two insectaries were done. Field trials was done in seven, five and six pairs of comparable release and control orchards across the Eastern and Western Cape during the seasons of 2019/2020, 2020/2021 and 2021/2022 respectively. Red scale infestation was monitored and a sample of 20 infested fruit from each orchard was randomly collected every four weeks. Aphytis spp. responsible for parasitism were identified and the percentage parasitism recorded. Results of this study of field trials suggest that the augmentation of A. melinus did not significantly increase the level of parasitism above that of the untreated control. Five repetitions with six replicates of flight and longevity tests were performed with wasps from each insectary. Wasps in the longevity test from two insectaries were kept at 23 °C and 65% RH with honey. Flight tests were performed in tubes of 16 by 30 cm, with a light above a clear, sticky ceiling at 23 °C and 65% RH. On average in five replicates, 65%, 33% and 17% A. melinus wasps were alive on day one, five and 10 respectively. The overall sex ratio was 1.58 for females to males, but 1.05, 2.19 and 2.66 for non-flyers, non-crawlers, crawlers, and flyers respectively. In flight tests for both insectaries combined, only 36.97% of wasps could initiate flight in 24 h while 56.96% remained on the tube floor, and 6.05% attempted to crawl upwards. No significant differences in flight performance were recorded between the two insectaries. Wasps from the local insectary lived significantly longer during the longevity tests but were shorter in transit than wasps from the overseas insectary. COI genes were sequenced and compared against Genbank sequences using BLAST. Molecular identifications did not confirm morphological identifications for all species, indicating unexpected genetic complexity. , Thesis (PhD) -- Faculty of Science, Zoology and Entomology, 2024
- Full Text:
- Date Issued: 2024-04-05
- Authors: De Beer, Ernst Friedrich Ludwig
- Date: 2024-04-05
- Subjects: Aphytis melinus , Aphytis , Aonidiella aurantii , Citrus Diseases and pests South Africa , Pests Biological control
- Language: English
- Type: Academic theses , Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/435638 , vital:73175 , DOI 10.21504/10962/435638
- Description: Aphytis lingnanensis was reared and tested in South Africa in the early 2000s for augmentation against red scale on citrus and was found to be ineffective. Aphytis melinus is now commercially available and it is important that the efficacy of augmentation thereof on red scale is determined locally. Field trials, fitness assessments and molecular identification on A. melinus from two insectaries were done. Field trials was done in seven, five and six pairs of comparable release and control orchards across the Eastern and Western Cape during the seasons of 2019/2020, 2020/2021 and 2021/2022 respectively. Red scale infestation was monitored and a sample of 20 infested fruit from each orchard was randomly collected every four weeks. Aphytis spp. responsible for parasitism were identified and the percentage parasitism recorded. Results of this study of field trials suggest that the augmentation of A. melinus did not significantly increase the level of parasitism above that of the untreated control. Five repetitions with six replicates of flight and longevity tests were performed with wasps from each insectary. Wasps in the longevity test from two insectaries were kept at 23 °C and 65% RH with honey. Flight tests were performed in tubes of 16 by 30 cm, with a light above a clear, sticky ceiling at 23 °C and 65% RH. On average in five replicates, 65%, 33% and 17% A. melinus wasps were alive on day one, five and 10 respectively. The overall sex ratio was 1.58 for females to males, but 1.05, 2.19 and 2.66 for non-flyers, non-crawlers, crawlers, and flyers respectively. In flight tests for both insectaries combined, only 36.97% of wasps could initiate flight in 24 h while 56.96% remained on the tube floor, and 6.05% attempted to crawl upwards. No significant differences in flight performance were recorded between the two insectaries. Wasps from the local insectary lived significantly longer during the longevity tests but were shorter in transit than wasps from the overseas insectary. COI genes were sequenced and compared against Genbank sequences using BLAST. Molecular identifications did not confirm morphological identifications for all species, indicating unexpected genetic complexity. , Thesis (PhD) -- Faculty of Science, Zoology and Entomology, 2024
- Full Text:
- Date Issued: 2024-04-05
Investigating occupation as frame for planning and developing agricultural extension VET skills for climate resilience: cross-case analysis of Alice, South Africa, and Gulu, Uganda
- Authors: Muhangi, Sidney
- Date: 2024-04-05
- Subjects: Agricultural extension work South Africa Alice , Agricultural extension work Uganda Gulu , Agricultural extension workers , Climate resilience , Skills development , Climatic changes
- Language: English
- Type: Academic theses , Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/436559 , vital:73282 , DOI 10.21504/10962/436559
- Description: In sub-Saharan Africa and most of the Global South, climate change is challenging work and livelihoods for smallholder farmers who depend on rainfed farming, demanding climate resilience. Smallholder agriculture in Africa remains a mainstay for most economies and livelihoods, including South Africa and Uganda. My firsthand experience in Uganda as a subsistence farmer revealed the vitality of extension services to farmers. Participating in VETAfrica 4.0, a VET skill planning project, sparked my interest in examining the adequacy of 'Occupation' as a skills planning tool for addressing contemporary climate change challenges faced by extension officers and farmers, with implications for skills development. This research sought to answer the question: What is the theoretical and practical history and current constitution of the agricultural extension officer occupation as a mediating unit of intervention for VET skills planning, and is it adequate for climate resilience? The study addressed five objectives. First, the study undertook a historical review of occupation as a mediating unit of intervention for skills planning. Secondly, the study examined current descriptions of the extension occupation as used for skills planning in Africa. Thirdly, in order to better understand the operationalisation of this skills planning instrument, the study examined aspects of skills development, specifically how VET preparation for extension work was taking place in response to the need for climate resilience through a curriculum review and the experiences and related work activities of extension services actors. The study also reviewed agricultural extension and VET policy, and labour market data for its responsiveness to climate resilience. In response to the findings of Objectives 1-4, a fifth objective was developed to offer expanded possibilities for a mediating unit of intervention for skills planning and development relevant to climate resilience in agricultural extension, as this appeared to be needed. To develop the study, I drew on the Social Ecosystems Model (SEM) for skills, which raises the issue of mediation in skills development. I also drew on Cultural-Historical Activity Theory (CHAT) to help theorise the mediation in the SEM for skills, where different activity systems (policy, training and extension, farming) were present. This framework allowed me to probe how these activity systems were mediating climate-resilient skills development with/for extension services (or not). Empirical data was produced through secondary and primary data, generated in two case study contexts using a cross-case design. Documentary analysis involved analysing policy documents, study curricula and historical literature to develop an understanding of historical sociology of occupation as a skills planning mediating unit and insight into contemporary understanding of how occupational frameworks are structured and deployed. Analysis was undertaken in two stages; firstly, through in-depth cases of occupation as mediating unit of intervention for skills planning, and aspects of skills development as influenced by this as influenced by this mediating unit (Chapter 5 and 6). This offered a first layer of analysis and insights into temporality, verticalities, mediation and horizontalities in the SEM for skills in each case. Secondly, abduction was undertaken to build models of the SEM for skills as found in each of the two countries using the SEM and CHAT analytical tools (Chapter 7), showing the need for skills planning tools that are more closely related to and relevant to the contexts of skills development. Findings revealed insights into the SEM for skills related to ecological time, notably a mismatch between the cultural-historical time of occupational skills planning and development, and the temporal demands for climate resilience. Historical analysis the deep rootedness of occupations and occupational structures in colonial histories and traditions, going back as far as the medieval era, with current occupations still bearing features of ancient occupational guild practices and hence not adequately responsive to climate change, affecting the SEM for skills in both cases and producing contradictions. Analysis further revealed that contemporary agricultural extension in Africa is decentralised and pluralistic, with few extension-related policies employed underdeveloped. Labour market in both South Africa and Uganda are not adequately orientated to climate resilience and fail to include climate resilience expertise, despite a need for this amongst farmers and by policy, revealing contradictions between various policy activity systems, which are not adequately facilitating. Empirical findings from study sites revealed that VET preparation for extension work lacks responsiveness to climate resilience within the skills ecosystem. Consequently, extension officers lack expertise in climate resilience, which is an increasing demand expressed by farmers and other horizontal activity systems in the SEM for skills. Through a more complex understanding of the extension officer occupation and its development in skills ecosystem in Africa, the study proposes a broader mediating unit of intervention for skills planning than that of ‘occupation’ only. The mediating unit of intervention put forward for skills planning is a workstream mapping approach for climate resilient extension training in VET. This planning approach has implications for skills development viewed as work, learning and living involving more than one activity system in the skills development landscape, thus also broadening the approach to VET. The study concludes with recommendations to further test this approach. Finally, it makes recommendations that can inform: 1) curriculum innovation, 2) extension practice, 3) policy, and 4) research. , Thesis (PhD) -- Faculty of Education, Secondary and Post School Education, 2024
- Full Text:
- Date Issued: 2024-04-05
- Authors: Muhangi, Sidney
- Date: 2024-04-05
- Subjects: Agricultural extension work South Africa Alice , Agricultural extension work Uganda Gulu , Agricultural extension workers , Climate resilience , Skills development , Climatic changes
- Language: English
- Type: Academic theses , Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/436559 , vital:73282 , DOI 10.21504/10962/436559
- Description: In sub-Saharan Africa and most of the Global South, climate change is challenging work and livelihoods for smallholder farmers who depend on rainfed farming, demanding climate resilience. Smallholder agriculture in Africa remains a mainstay for most economies and livelihoods, including South Africa and Uganda. My firsthand experience in Uganda as a subsistence farmer revealed the vitality of extension services to farmers. Participating in VETAfrica 4.0, a VET skill planning project, sparked my interest in examining the adequacy of 'Occupation' as a skills planning tool for addressing contemporary climate change challenges faced by extension officers and farmers, with implications for skills development. This research sought to answer the question: What is the theoretical and practical history and current constitution of the agricultural extension officer occupation as a mediating unit of intervention for VET skills planning, and is it adequate for climate resilience? The study addressed five objectives. First, the study undertook a historical review of occupation as a mediating unit of intervention for skills planning. Secondly, the study examined current descriptions of the extension occupation as used for skills planning in Africa. Thirdly, in order to better understand the operationalisation of this skills planning instrument, the study examined aspects of skills development, specifically how VET preparation for extension work was taking place in response to the need for climate resilience through a curriculum review and the experiences and related work activities of extension services actors. The study also reviewed agricultural extension and VET policy, and labour market data for its responsiveness to climate resilience. In response to the findings of Objectives 1-4, a fifth objective was developed to offer expanded possibilities for a mediating unit of intervention for skills planning and development relevant to climate resilience in agricultural extension, as this appeared to be needed. To develop the study, I drew on the Social Ecosystems Model (SEM) for skills, which raises the issue of mediation in skills development. I also drew on Cultural-Historical Activity Theory (CHAT) to help theorise the mediation in the SEM for skills, where different activity systems (policy, training and extension, farming) were present. This framework allowed me to probe how these activity systems were mediating climate-resilient skills development with/for extension services (or not). Empirical data was produced through secondary and primary data, generated in two case study contexts using a cross-case design. Documentary analysis involved analysing policy documents, study curricula and historical literature to develop an understanding of historical sociology of occupation as a skills planning mediating unit and insight into contemporary understanding of how occupational frameworks are structured and deployed. Analysis was undertaken in two stages; firstly, through in-depth cases of occupation as mediating unit of intervention for skills planning, and aspects of skills development as influenced by this as influenced by this mediating unit (Chapter 5 and 6). This offered a first layer of analysis and insights into temporality, verticalities, mediation and horizontalities in the SEM for skills in each case. Secondly, abduction was undertaken to build models of the SEM for skills as found in each of the two countries using the SEM and CHAT analytical tools (Chapter 7), showing the need for skills planning tools that are more closely related to and relevant to the contexts of skills development. Findings revealed insights into the SEM for skills related to ecological time, notably a mismatch between the cultural-historical time of occupational skills planning and development, and the temporal demands for climate resilience. Historical analysis the deep rootedness of occupations and occupational structures in colonial histories and traditions, going back as far as the medieval era, with current occupations still bearing features of ancient occupational guild practices and hence not adequately responsive to climate change, affecting the SEM for skills in both cases and producing contradictions. Analysis further revealed that contemporary agricultural extension in Africa is decentralised and pluralistic, with few extension-related policies employed underdeveloped. Labour market in both South Africa and Uganda are not adequately orientated to climate resilience and fail to include climate resilience expertise, despite a need for this amongst farmers and by policy, revealing contradictions between various policy activity systems, which are not adequately facilitating. Empirical findings from study sites revealed that VET preparation for extension work lacks responsiveness to climate resilience within the skills ecosystem. Consequently, extension officers lack expertise in climate resilience, which is an increasing demand expressed by farmers and other horizontal activity systems in the SEM for skills. Through a more complex understanding of the extension officer occupation and its development in skills ecosystem in Africa, the study proposes a broader mediating unit of intervention for skills planning than that of ‘occupation’ only. The mediating unit of intervention put forward for skills planning is a workstream mapping approach for climate resilient extension training in VET. This planning approach has implications for skills development viewed as work, learning and living involving more than one activity system in the skills development landscape, thus also broadening the approach to VET. The study concludes with recommendations to further test this approach. Finally, it makes recommendations that can inform: 1) curriculum innovation, 2) extension practice, 3) policy, and 4) research. , Thesis (PhD) -- Faculty of Education, Secondary and Post School Education, 2024
- Full Text:
- Date Issued: 2024-04-05
Phthalocyanine-based bio-functional conjugates: photodynamic therapy and photoantimicrobial chemotherapeutic efficacy evaluation in-vitro
- Authors: Magadla, Aviwe
- Date: 2024-04-05
- Subjects: Photochemotherapy , Anti-infective agents , Biofilms , Active oxygen , Quantum yield , Phthalocyanines
- Language: English
- Type: Academic theses , Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/435918 , vital:73212 , DOI 10.21504/10962/435918
- Description: This thesis reports on the syntheses and characterisation of symmetrical and asymmetrical phthalocyanines (Pcs) with different ring substituents derived to form either cationic styryl pyridine, cationic styryl pyridine triphenylphosphonium (TPP+)-based, benzothiazole, cationic pyridyl-dihydrothiazole and other closely related groups. The starting Pc complex of the synthesised Pc derivatives was typically obtained through the cyclotetramerisation of a substituted phthalonitrile. Then, depending on the desired final complex, the desired complexes were synthesised through the Knoevenagel condensation, alkylation reaction, and Schiff base reaction. Furthermore, silica nanoparticles (SiNPs) were also used to encapsulate Pcs. Following aminopropyl triethoxysilane amino (APTES) functionalisation of the surface of the Pc@SiNPs-APTES, biomolecules such as gallic acid, folic acid, and ampicillin were covalently attached to the surface. Additionally, Pc@SiNPs-APTES is protonated with 1,3-propanesultone. The pair of synthesised asymmetric Pcs is attached to ciprofloxacin (CIP) via an amide bond. Different analytical methods were used to characterise the Pcs and their conjugates. The photophysics and photochemistry of the Pcs both by themselves and in their conjugate form when doped with SiNPs. The cationic Pcs were able to produce sufficient singlet oxygen on their own in most cases. This is explained by the Pcs greater solubility in water. Since singlet oxygen is produced from the triplet state, singlet oxygen quantum yield (Δ) values complement triplet quantum yield (T) values. Low Δ values could be attributed to ineffective energy transfer; screening effects may have prevented the excited triplet state of the Pcs from interacting with the ground state molecular oxygen, lowering the Δ values. In other instances, the Pcs' protection by the SiNPs could be credited with extending the triplet lifetime. The direct connection of Pcs with CIP increased the formation of T and Δ in ABSTRACT comparison to Pcs alone. Both in planktonic and biofilm form, the cationic Pcs and conjugates showed enhanced bacterial elimination. The Pcs and conjugates demonstrated significant activity in photodynamic therapy treatment (PDT) experiments at the tested doses. In both PDT and photodynamic antimicrobial chemotherapy (PACT) treatment, the cationic Pcs outperformed the neutral Pc in terms of biological activity. , Thesis (PhD) -- Faculty of Science, Chemistry, 2024
- Full Text:
- Date Issued: 2024-04-05
- Authors: Magadla, Aviwe
- Date: 2024-04-05
- Subjects: Photochemotherapy , Anti-infective agents , Biofilms , Active oxygen , Quantum yield , Phthalocyanines
- Language: English
- Type: Academic theses , Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/435918 , vital:73212 , DOI 10.21504/10962/435918
- Description: This thesis reports on the syntheses and characterisation of symmetrical and asymmetrical phthalocyanines (Pcs) with different ring substituents derived to form either cationic styryl pyridine, cationic styryl pyridine triphenylphosphonium (TPP+)-based, benzothiazole, cationic pyridyl-dihydrothiazole and other closely related groups. The starting Pc complex of the synthesised Pc derivatives was typically obtained through the cyclotetramerisation of a substituted phthalonitrile. Then, depending on the desired final complex, the desired complexes were synthesised through the Knoevenagel condensation, alkylation reaction, and Schiff base reaction. Furthermore, silica nanoparticles (SiNPs) were also used to encapsulate Pcs. Following aminopropyl triethoxysilane amino (APTES) functionalisation of the surface of the Pc@SiNPs-APTES, biomolecules such as gallic acid, folic acid, and ampicillin were covalently attached to the surface. Additionally, Pc@SiNPs-APTES is protonated with 1,3-propanesultone. The pair of synthesised asymmetric Pcs is attached to ciprofloxacin (CIP) via an amide bond. Different analytical methods were used to characterise the Pcs and their conjugates. The photophysics and photochemistry of the Pcs both by themselves and in their conjugate form when doped with SiNPs. The cationic Pcs were able to produce sufficient singlet oxygen on their own in most cases. This is explained by the Pcs greater solubility in water. Since singlet oxygen is produced from the triplet state, singlet oxygen quantum yield (Δ) values complement triplet quantum yield (T) values. Low Δ values could be attributed to ineffective energy transfer; screening effects may have prevented the excited triplet state of the Pcs from interacting with the ground state molecular oxygen, lowering the Δ values. In other instances, the Pcs' protection by the SiNPs could be credited with extending the triplet lifetime. The direct connection of Pcs with CIP increased the formation of T and Δ in ABSTRACT comparison to Pcs alone. Both in planktonic and biofilm form, the cationic Pcs and conjugates showed enhanced bacterial elimination. The Pcs and conjugates demonstrated significant activity in photodynamic therapy treatment (PDT) experiments at the tested doses. In both PDT and photodynamic antimicrobial chemotherapy (PACT) treatment, the cationic Pcs outperformed the neutral Pc in terms of biological activity. , Thesis (PhD) -- Faculty of Science, Chemistry, 2024
- Full Text:
- Date Issued: 2024-04-05
Plankton and macroinvertebrate dynamics in the Khakhea–Bray transboundary aquifer region
- Mungenge, Chipo Perseverance
- Authors: Mungenge, Chipo Perseverance
- Date: 2024-04-05
- Subjects: Vernal pools Africa, Southern , Water quality , Crustacea , Freshwater salinization , Food chains (Ecology)
- Language: English
- Type: Academic theses , Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/435674 , vital:73178 , DOI 10.21504/10962/435674
- Description: Temporary wetlands are prevalent in semi–arid and arid climates across the globe and harbour unique faunal assemblages that significantly contribute to regional aquatic biodiversity. This study aims to enhance our understanding of the ecological dynamics of temporary wetland ecosystems, focusing on plankton dynamics, large branchiopod diversity, trophic dynamics, water quality and the impacts of freshwater salinisation in temporary pans in the Khakhea Bray Transboundary aquifer region in the North west Province, South Africa. This body of work represents field, laboratory and writing components which span the period May 2021 to December 2023. The results from this study revealed seasonal patterns in plankton diversity with a winter peak in phytoplankton diversity dominated by Zygnematophyceae species, while Chlorophyceae were dominant in summer. Zooplankton diversity was high in summer as compared to winter, with both Rotifera and Copepoda dominant in both seasons. Six large branchiopod species were found in the region, and three of these were new distribution records for the North west Province, including the first record of Phallocryptus spinosa in the salt pan that was sampled in summer. Large branchiopod diversity was mainly influenced by water temperature and phosphorous in summer, while sediment sodium influenced the diversity in winter. The stable isotope analyses used to determine trophic dynamics in these temporary pans revealed that the food web had four trophic levels, with the top predators being the notonectids Anisops sp. The dominant consumers were predatory insects such as Sigara sp., Anisops sp., Lestes sp., Rhantus sp. and Cybister sp. adults and larvae, as well as detritivorous Tomopterna sp. tadpoles. High trophic niche overlaps were found between the notonectids and the dytiscids. These temporary pans are susceptible to anthropogenic impacts, and disturbed pans were found to have elevated pH, ammonium, phosphates and dissolved oxygen compared to the undisturbed pans. A strong positive relationship was observed between chl–a and temperature, pH, dissolved oxygen, phosphates and ammonium. Chlorophyll–a concentration increased as surface area and the distance from kraals, buildings and latrines decreased. Freshwater salinisation was found to cause notable shifts in abiotic factors and benthic phytoplankton communities, favouring the proliferation of saline–tolerant diatom species at the cost of more sensitive taxa. The study also revealed that in interaction with salinisation, time also exerted a notable influence on shaping the benthic phytoplankton community. Salinity levels of 2.5 ppt and above led to significant decreases in emergent taxa richness and abundance, with Spinicaudata and Ostracoda being the most sensitive taxa to high salinities. There was a limited effect on community hatching phenology dynamics from salinity. This suggests that the main impact of salinisation in these systems will be reductions in hatching success and, hence, reduced recruitment. The study highlights the vulnerability of temporary pan ecosystems to anthropogenic influences and the complexities of interactions of organisms and the environmental conditions in these systems. , Thesis (PhD) -- Faculty of Science, Zoology and Entomology, 2024
- Full Text:
- Date Issued: 2024-04-05
- Authors: Mungenge, Chipo Perseverance
- Date: 2024-04-05
- Subjects: Vernal pools Africa, Southern , Water quality , Crustacea , Freshwater salinization , Food chains (Ecology)
- Language: English
- Type: Academic theses , Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/435674 , vital:73178 , DOI 10.21504/10962/435674
- Description: Temporary wetlands are prevalent in semi–arid and arid climates across the globe and harbour unique faunal assemblages that significantly contribute to regional aquatic biodiversity. This study aims to enhance our understanding of the ecological dynamics of temporary wetland ecosystems, focusing on plankton dynamics, large branchiopod diversity, trophic dynamics, water quality and the impacts of freshwater salinisation in temporary pans in the Khakhea Bray Transboundary aquifer region in the North west Province, South Africa. This body of work represents field, laboratory and writing components which span the period May 2021 to December 2023. The results from this study revealed seasonal patterns in plankton diversity with a winter peak in phytoplankton diversity dominated by Zygnematophyceae species, while Chlorophyceae were dominant in summer. Zooplankton diversity was high in summer as compared to winter, with both Rotifera and Copepoda dominant in both seasons. Six large branchiopod species were found in the region, and three of these were new distribution records for the North west Province, including the first record of Phallocryptus spinosa in the salt pan that was sampled in summer. Large branchiopod diversity was mainly influenced by water temperature and phosphorous in summer, while sediment sodium influenced the diversity in winter. The stable isotope analyses used to determine trophic dynamics in these temporary pans revealed that the food web had four trophic levels, with the top predators being the notonectids Anisops sp. The dominant consumers were predatory insects such as Sigara sp., Anisops sp., Lestes sp., Rhantus sp. and Cybister sp. adults and larvae, as well as detritivorous Tomopterna sp. tadpoles. High trophic niche overlaps were found between the notonectids and the dytiscids. These temporary pans are susceptible to anthropogenic impacts, and disturbed pans were found to have elevated pH, ammonium, phosphates and dissolved oxygen compared to the undisturbed pans. A strong positive relationship was observed between chl–a and temperature, pH, dissolved oxygen, phosphates and ammonium. Chlorophyll–a concentration increased as surface area and the distance from kraals, buildings and latrines decreased. Freshwater salinisation was found to cause notable shifts in abiotic factors and benthic phytoplankton communities, favouring the proliferation of saline–tolerant diatom species at the cost of more sensitive taxa. The study also revealed that in interaction with salinisation, time also exerted a notable influence on shaping the benthic phytoplankton community. Salinity levels of 2.5 ppt and above led to significant decreases in emergent taxa richness and abundance, with Spinicaudata and Ostracoda being the most sensitive taxa to high salinities. There was a limited effect on community hatching phenology dynamics from salinity. This suggests that the main impact of salinisation in these systems will be reductions in hatching success and, hence, reduced recruitment. The study highlights the vulnerability of temporary pan ecosystems to anthropogenic influences and the complexities of interactions of organisms and the environmental conditions in these systems. , Thesis (PhD) -- Faculty of Science, Zoology and Entomology, 2024
- Full Text:
- Date Issued: 2024-04-05
Case in modern standard Arabic
- Ghammaz, Hamzah Saleh Theyab
- Authors: Ghammaz, Hamzah Saleh Theyab
- Date: 2024-04-04
- Subjects: Arabic language Syntax , Arabic language Case , Minimalist theory (Linguistics) , Grammar, Comparative and general Verb phrase , Predicate , Tritransitive verb , Grammar, Comparative and general Clitics
- Language: English
- Type: Academic theses , Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/435593 , vital:73171 , DOI 10.21504/10962/435593
- Description: This thesis provides a novel account of case checking in Modern Standard Arabic (henceforth MSA). It argues against the concept that nominative case in topic and comment structures is default. Default or inherent case is not related to case filter, nor is it assigned by any syntactic method. Some linguists claim that the default case in Arabic language is employed only when no case assigner is available. I argue, in light of the minimalist program (henceforth MP), that default (inherent) case is always a problem for syntactic theory and that the nominative case which the topic and comment sentences bear is valued by a functional head. The topic and comment constructions contain a predicational head (Pred)- a functional head, that is equivalent to vP which occurs in verbal constructions. The head of PredP is accountable for nominative case value on the topic and comment structures. This thesis also provides a novel paradigm regarding the clitics that appear at the end of verbs in MSA. This paradigm proves that these clitics are not agreement, tense, nor mood markers but rather Verbal Case markers and it provides a minimalist program account to explain case checking on verbs in MSA. Regarding sentence initial DP, and contra to the proposal that in SVO sentence initial DP is a subject, I have scrutinised the nature of this DP and provided enough evidence that it is a topic. Additionally, I have investigated the relationship between agreement asymmetry and the position of the subject in MSA from the minimalist feature inheritance account viewpoint. Mainly, I reviewed null pro hypothesis which proved to be redundant to account for the derivation of VSO or SVO word orders. I have also proved what were considered agreement markers are not agreement markers but resumptive pronouns. Finally, I proved that there is not agreement asymmetry in MSA. Agreement pattern in MSA results from the agree operation and it is achieved under Probe-Goal alignment; regardless of whether the Goal is raised up to Spec-TP or remains in situ (Spec-VP), the agreement is not supposed to change. This conclusion is in harmony with the principles of MP Agree Theory. , Thesis (PhD) -- Humanities, Linguistics and Applied Language Studies, 2024
- Full Text:
- Date Issued: 2024-04-04
- Authors: Ghammaz, Hamzah Saleh Theyab
- Date: 2024-04-04
- Subjects: Arabic language Syntax , Arabic language Case , Minimalist theory (Linguistics) , Grammar, Comparative and general Verb phrase , Predicate , Tritransitive verb , Grammar, Comparative and general Clitics
- Language: English
- Type: Academic theses , Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/435593 , vital:73171 , DOI 10.21504/10962/435593
- Description: This thesis provides a novel account of case checking in Modern Standard Arabic (henceforth MSA). It argues against the concept that nominative case in topic and comment structures is default. Default or inherent case is not related to case filter, nor is it assigned by any syntactic method. Some linguists claim that the default case in Arabic language is employed only when no case assigner is available. I argue, in light of the minimalist program (henceforth MP), that default (inherent) case is always a problem for syntactic theory and that the nominative case which the topic and comment sentences bear is valued by a functional head. The topic and comment constructions contain a predicational head (Pred)- a functional head, that is equivalent to vP which occurs in verbal constructions. The head of PredP is accountable for nominative case value on the topic and comment structures. This thesis also provides a novel paradigm regarding the clitics that appear at the end of verbs in MSA. This paradigm proves that these clitics are not agreement, tense, nor mood markers but rather Verbal Case markers and it provides a minimalist program account to explain case checking on verbs in MSA. Regarding sentence initial DP, and contra to the proposal that in SVO sentence initial DP is a subject, I have scrutinised the nature of this DP and provided enough evidence that it is a topic. Additionally, I have investigated the relationship between agreement asymmetry and the position of the subject in MSA from the minimalist feature inheritance account viewpoint. Mainly, I reviewed null pro hypothesis which proved to be redundant to account for the derivation of VSO or SVO word orders. I have also proved what were considered agreement markers are not agreement markers but resumptive pronouns. Finally, I proved that there is not agreement asymmetry in MSA. Agreement pattern in MSA results from the agree operation and it is achieved under Probe-Goal alignment; regardless of whether the Goal is raised up to Spec-TP or remains in situ (Spec-VP), the agreement is not supposed to change. This conclusion is in harmony with the principles of MP Agree Theory. , Thesis (PhD) -- Humanities, Linguistics and Applied Language Studies, 2024
- Full Text:
- Date Issued: 2024-04-04