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Honorary Citation for the Conferment of Doctor of Laws honoris causa - Tandabantu Tennyson August

  • Authors: Rhodes University , Martin, Tom
  • Date: 2024-14-05
  • Subjects: Uncatalogued
  • Language: English
  • Type: Speeches , Transcripts, speech , text
  • Identifier: http://hdl.handle.net/10962/432591 , vital:72885
  • Description: Rhodes University Honorary Doctorate Citation (5 April 2024) Tandabantu Tennyson August: 1980s. South Africa. In the Bantustans of the time, like the Transkei, the youth have little reason for hope. They have much reason for despair. Their choices seem limited to the politics of struggle or to crime, an attempt to gain some kind of advantage from the meagre and unacceptable options on offer. In those bleak times, what was needed was visionaries. People who could see beyond the current circumstances to a different future and imagine how best to prepare for it. Not as idealists, but as pragmatists. What would happen once circumstances change, once the struggle had succeeded? Would we be ready for it? What qualities would the youth need to have in order to both benefit from and participate in a new dispensation? One such visionary was Tandabantu Tennyson August, and it is my distinct pleasure to have the opportunity to tell you more about him. Born in 1948, Mr. August matriculated from Healdtown High School, before pursuing higher education at the University of Transkei, where obtained a Bachelor of Arts degree majoring in English and Geography. This was followed by Comparative Curriculum Studies at the University of South Africa, alongside obtaining teaching certificates from Lovedale and Cicira teacher training colleges, with majors in Physical Science, Mathematics, Science, and Mathematics. This solid educational foundation laid the groundwork for his impactful career in education. He taught at Wongalethu High, St Johns College and was deputy principal at Norwood, before taking up his first principalship, at Thanga High School in 1980. From 1984 to 1990 he was principal of Ndamase High School. During his tenure there, the matric pass rate never fell below 90%. From 1991 to 1995 he was principal Isivivane High School during which time the school was promoted from a primary to a high school. Following his distinguished service at schools, he worked at the Eastern Cape Department of Basic Education, first as a deputy chief education specialist (1996 – 2006) and then as chief education specialist (2006-2010). During that time, he played a pivotal role in establishing (in conjunction with Rhodes University) and being the provincial coordinator the Advanced Certificate in Education in English, followed by ACEs in mathematical literacy and life orientation. In 2016 he received a provincial teaching award for excellence. In 2017 he was awarded the Kade Asmal award for excellence in teaching. To this day, he remains an Executive member of the eastern cape Education advisory council. Quite a career. But there’s something I haven’t mentioned. He was also an accomplished rugby player of international standing. While at Lovedale College, he was selected to represent Border and then the South African African Rugby Board, playing England in Gqeberha in 1972, in a team that would later be known as the black springboks. He eventually received his green and gold springbok blazer as just recognition of his achievement. He incorporated his love of sport into his vision for the youth under his care, as part of his overriding mission of educating the whole person. He got everyone involved in sport, if not as a player, then as a supporter. Especially during his time as principal of Ndamase High School, I am led to believe, it was extremely intimidating for opposing teams to play them. Not only at Ndamase home games, but especially at their away games. There would be one bus for the team players, and six buses for the supporters. From 1986 – 1990: he was president of the Transkei schools` sports union (TSSU). But there’s yet another thing I haven’t mentioned. In 1981, just as his career as an educational leader was really taking off, he was involved in a terrible motor vehicle accident. It left him permanently disabled and, for much of his life, a wheelchair user. Rather than stopping him, it simply added another string to his bow, now as an advocate for the disabled. From 2012 – 2022: Chairperson Eastern Cape South African National Association For Special Education (SANASE): this organization cater for the education and wellbeing of learners with disabilities and special needs. In 2023, he was the national deputy president of the same organisation. From 2013 – to date: he is a Board Member on the National Council of & for persons with disabilities (NCPD). I had the pleasure of an extensive conversation with one of Mr August’s former pupils at Ndamase High, Professor Deyi Mbelani, the current director of Rhodes University’s Institute for the Study of Englishes in Africa. He told me many stories about Mr August’s leadership, that I only wish I had time to share with you now. I put it to Professor Mbelani that, having read about Mr August, the word that stood out for me was “dedication.” He agreed that “dedication” was the word, but that I must not leave out another: “vision”. It is Mr August’s status as a visionary that best defines him, he said. Going back over the above, I think he is right. Mr Chancellor I have the honour to request you to confer the degree of Doctor of Laws honoris causa on the Mr Tandabantu Tennyson August. *The above citation draws heavily on documents submitted as part of the honorary doctorate nomination process and others compiled by the Division of Communications and Advancement. - Tom Martin.
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  • Date Issued: 2024-14-05

A framework for designing a gamified system that promotes knowledge of water sustainability

  • Authors: Kunjuzwa, Dumani Tau
  • Date: 2024-12
  • Subjects: Computer science , User interfaces (Computer systems) , Water-supply -- Management
  • Language: English
  • Type: Doctoral theses , text
  • Identifier: http://hdl.handle.net/10948/69349 , vital:77216
  • Description: Water shortages are becoming increasingly common and raising awareness thereof has been proposed as a key strategy for empowering citizens with knowledge relevant to promoting water sustainability. This knowledge should incorporate indigenous knowledge, which is unique and confined to a particular culture. Indigenous knowledge has been recognised as the key to sustainable social and economic development. Knowledge incorporated within appropriate technologies can be a transformative solution to promote sustainable consumption of natural resources. This study aimed to develop a framework with strong theoretical connections that can be used as a guide for designing and developing technological solutions for promoting knowledge, attitude, and practices (KAP) of water sustainability. Gamification, serious games, and community social networks were identified as appropriate technologies for implementing these solutions. Design Science Research (DSR) was an appropriate research methodology for this research. As the requirement of the DSR methodology, a framework was designed that considered relevant theories. The two theories (Self-Determination Theory and Social Capital Theory) were incorporated into the framework. The framework can guide other researchers in developing gamified systems that promote the KAPs of water sustainability. This framework was the theoretical artefact of the study. The research context was the Eastern Cape Province of South Africa where the data was collected from two municipalities namely, the Nelson Mandela Bay and Buffalo City Metro, which have both experienced water shortages in recent years. Quantitative and qualitative data collection methods were used. Qualitative data was collected from brainstorming sessions and expert reviews that were conducted with various stakeholders that assisted with designing and evaluating the prototype designs of the gamified solution. For the design of the study’s artefacts, a participatory research approach was adopted. Participants were recruited to complete an online survey, which ran for three months. The findings revealed that citizens’ knowledge is closely correlated to the attitudes and practices of citizens regarding water sustainability. In addition, the findings showed that the knowledge of the citizens in the Eastern Cape Province was relatively low on water practices such as conservation and filtering methods. These results were considered in the design of the practical artefact and the instantiation findings. One limitation of this study was the limited number of indigenous participants in the survey. Other limitations were the lack of experts with indigenous knowledge and the lack of indigenous knowledge documentation. The promotion of water sustainability knowledge in communities would be more effective with the use of gamification and social community networks. In principle, the enhancement in water sustainability knowledge would promote the citizens’ good practices and attitudes (behavioural) related to water sustainability. Since 2015, a significant portion of South Africa's Eastern Cape Province has been suffering from a severe drought. This province is one of the regions of the country where weather patterns have changed dramatically, and as a result, most households were left vulnerable to the water shortage problem. While the broad topic of water sustainability is widely discussed in the literature, the role of appropriate technologies in promoting knowledge of water sustainability is still under-researched. This gap provided a significant potential for investigation by sustainability to design a technological and theoretical solution for promoting knowledge of water sustainability. This study contributes to the body of knowledge by delivering three DSR artefacts namely, a Framework for Designing a Gamified System that Promotes Knowledge of Water Sustainability; the design guidelines that supplement the framework, and a practical instantiation of the framework. , Thesis (DPhil) -- Faculty of Science, School of Computer Science, Mathematics, Physics and Statistics, 2024
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  • Date Issued: 2024-12

A multistep synthesis of zidovudine in continuous flow systems

  • Authors: Kwakhanya, Mkwakwi
  • Date: 2024-12
  • Subjects: HIV -- South Africa , HIV infections -- Diagnosis , Antiretroviral agents -- South Africa
  • Language: English
  • Type: Doctoral theses , text
  • Identifier: http://hdl.handle.net/10948/69393 , vital:77251
  • Description: Universal access to antiretroviral drugs is still a challenge in developing nations. This promoted an investigation into an efficient process towards the synthesis of zidovudine (AZT), a nucleoside reverse transcriptase inhibitor (NRTI) that is used to treat HIV/AIDS. It was the first antiretroviral drug approved by the FDA and it is still widely used today. AZT works by blocking the enzyme reverse transcriptase, which is used by HIV to copy its genetic material. This prevents HIV from replicating and spreading throughout the body. AZT is usually taken in combination with other antiretroviral drugs. AZT was originally used as a single-drug therapy, but it is no longer recommended for this purpose as HIV can become resistant to AZT if it is used alone. Consequently, AZT is most commonly used as part of a combination therapy; this means that it is taken with other antiretroviral drugs. This helps to prevent HIV from becoming resistant to AZT. AZT can be used to prevent mother-to-child transmission of HIV; it is usually given to HIV-positive women during pregnancy and childbirth. AZT can also be used to treat post-exposure prophylaxis (PEP); this is a course of antiretroviral drugs that is taken after a possible exposure to HIV. The application of continuous flow microreactors to reaction chemistries, such as this, could provide a potentially practical solution that could be used to meet the rising needs for antiretroviral drugs in Africa and to give new opportunities for efficient local drug manufacture. Consequently, the focus of this research was to develop safe and efficient processes towards AZT by taking advantage of micro reactor technology. Furthermore, since there is no literature on continuous flow synthesis of this drug, this research extensively unearthed interesting continuous flow processes towards zidovudine. , Thesis (PhD) -- Faculty of Science, School of Biomolecular & Chemical Sciences, 2024
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  • Date Issued: 2024-12

A strategy towards an it governance-focused implementation of Egovernment initiatives in the Eastern Cape provincial government

  • Authors: Magade, Siyabonga
  • Date: 2024-12
  • Subjects: Internet in public administration , Government communication systems , Public administration -- Data processing
  • Language: English
  • Type: Master's theses , text
  • Identifier: http://hdl.handle.net/10948/68725 , vital:77085
  • Description: ICT plays a very important role in transforming organisations as well as governments around the world through eGovernment. A good implementation of eGovernment promises to transform and enhance the provision of services to citizens. The benefits of eGovernment will enable the transparency of government and engender the trust of its citizens therein. Citizens will have access to online government services that will minimise the long queues that citizens need to endure to access government services. eGovernment implementation requires ICT technologies, however, dependency on the implementation of ICT technologies to drive eGovernment initiatives will not alone succeed in transforming the delivery of services in government. Therefore, the implementation of ICT technologies in government must be focused on good IT governance principles. Such principles enable the executive council and management to direct and control the application both now and in the future of use of ICT in government. Therefore, this study develops a strategy artefact that is focused on good IT governance principles to assist in the execution of eGovernment programs in the Eastern Cape Provincial Government. , Thesis (MPhil) -- Faculty of Engineering, the Built Environment, and Technology, School of Information Technology, 2024
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  • Date Issued: 2024-12

Achievement in mathematics through self-directed learning facilitation: an impact evaluation of an offline technological approach

  • Authors: Zinn, Paméla Olive
  • Date: 2024-12
  • Subjects: Mathematics -- Study and teaching (Secondary) -- South Africa , Mathematical ability , Academic achievement -- South Africa
  • Language: English
  • Type: Doctoral theses , text
  • Identifier: http://hdl.handle.net/10948/68385 , vital:76992
  • Description: International assessments indicate that mathematics education in South Africa is still in a crisis of significant proportions. This is reflected in the low pass rate of Grade 12 mathematics learners in South Africa in general, and in the Eastern Cape Province in particular. In response, the Govan Mbeki Mathematics Development Center (GMMDC) of the Nelson Mandela University (NMU) in the Eastern Cape developed an intervention strategy. A Techno-Blended support Model for teaching and learning mathematics (TBM), used as an intervention strategy, provides learners with potential from disadvantaged communities and under-resourced schools with 21st-century education technology. The defining features of the strategy which distinguishes it from others are that it is technology-enhanced, providing the learner access to mathematics teaching and learning without the need for Internet connectivity, that is, offline, incorporating blended learning into the approach. This ex-post study, using secondary analysis, evaluates the impact of the defining features of the strategy on learners' self-directed learning skills acquisition or enhancement for mathematics learning. Firstly, statistical analysis of secondary qualitative and quantitative data in a mixed methods approach, with primary qualitative data integrated into the secondary qualitative data employing quantification, is undertaken. The quantified data is then compared with the quantitative data (methodologic triangulation technique). Secondly, the theory-based Contribution Analysis is undertaken to increase the validity and credibility of the findings of the statistical analysis, providing an additional layer of triangulation. The study revealed that providing 21st-century digital education technology for use offline, within a blended learning environment, leads to a significant improvement in learner mathematics knowledge; conceptual understanding; positive self-perceptions; and finally, to the required intrinsic motivation to learn. Analysed data, obtained from the original study, indicates a positive correlation between learners who participated in the intervention strategy and enrolment in STEM-related courses at tertiary institutes. , Thesis (DPhil) -- Faculty of Education, School of Postgraduate education, 2024
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  • Date Issued: 2024-12

Ammendments to the labour law relations act 66 of 1995 to addressing violent and intractable strikes

  • Authors: Gavu, Siphelele
  • Date: 2024-12
  • Subjects: Labor laws and legislation -- South Africa , Strikes and lockouts -- Law and legislation -- South Africa , Labor disputes -- South Africa
  • Language: English
  • Type: Master's theses , text
  • Identifier: http://hdl.handle.net/10948/68692 , vital:77082
  • Description: The main research question for this treatise is to determine whether the South African legal framework provides effective regulations in curbing violent and intractable strikes. To answer the research question, the research explored the evolution of the right to strike in South Africa, analysing its socio-economic impact and the transition from a repressive regime to a democratic one. The study assessed international, regional, and national legal frameworks, focusing on the right to strike and its regulation. Amendments to the LRA, including introducing rules for picketing, mandatory secret ballots for strikes, and advisory arbitration for dysfunctional strikes, were evaluated. The findings indicate that while these amendments represent a significant step in addressing the issues of violent strikes in an employment context, their effectiveness is limited. Persistent challenges include the frequent disregard by trade unions and their members for legal measures. This reflects the deeper socio- economic and political issues. The study suggests that the effectiveness of these legislative changes is hindered by ongoing social and economic inequalities, highlighting the need for broader socio-political solutions beyond legislative amendments. This comprehensive analysis explains the complexities surrounding strike actions in South Africa and the balance between upholding labour rights and maintaining workplace discipline and order. , Thesis (LLM) -- Faculty of Law, School of Mercantile Law, 2024
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  • Date Issued: 2024-12

Associations between patterns of wild ungulate patch use, soil carbon and albedo in montane grasslands

  • Authors: Mc Gregor, Steven
  • Date: 2024-12
  • Subjects: Grassland ecology , Global environmental change , Climatic changes
  • Language: English
  • Type: Doctoral theses , text
  • Identifier: http://hdl.handle.net/10948/69382 , vital:77250
  • Description: Grassy ecosystems are essential for human survival, providing key services including food production, water provisioning and moderating climate. Yet, grassy ecosystems remain undervalued due to misconceptions that they are remnants of degraded states of forest – a view that continues to influence climate change policies. This thesis explores the links between wild, free-roaming ungulate grazers and climate drivers, including carbon storage and surface albedo (i.e., reflectance of solar radiation), through their impacts on vegetation and soils. Using black wildebeest (Connochaetes gnou) as a model wild species, I compared their grazing patterns in an Afromontane grassland in the eastern Karoo, South Africa, to those of short-duration cattle grazing systems in similar nearby grasslands (Chapter 2). While short-duration grazing aims to mimic spatiotemporal wild ungulate grazing patterns to supposedly enhance ecosystem functioning and soil carbon stocks, I found that wildebeest had ~50% shorter grazing durations and much shorter rest intervals (1-5 days versus 60-365 days), revealing key differences in grazing patterns that may affect vegetation and climate feedbacks. Next, I examined spatial variations in soil organic carbon (SOC) stocks between grass growth forms that differ in grazing tolerance (Chapter 3). Red grass (Themeda triandra) tussock patches, sensitive to frequent grazing, had higher SOC to a soil depth of 20 cm (61.45 ± 1.59 Mg C·ha-1)than intensively grazed, prostrate-growing Cynodon dactylon grazing lawns (55.43 ± 3.40Mg C·ha-1), likely due to greater shading and soil moisture beneath tussocks which drives microbial decomposition. Seasonal albedo variations were then assessed across distinct grassland patch types among seasons to determine whether albedo varies seasonally at fine patch-scales between grass patches, between shrub and grass patches, and with grazing (Chapter 4). Albedo was lower during the growing season compared to dormancy, and was consistently lower in dwarf shrub (Pentzia incana) encroached patches compared to grass patches. No albedo differences between grazed and less-grazed tussock grass patches of the same species were found, although intensively grazed grazing lawns had consistently higher albedo than most patch types. Finally, I evaluated trade-offs between plant carbon, albedo, and their impacts on radiative forcing (i.e., atmospheric warming/cooling) resulting from patch type changes commonly found in grassy ecosystems (Chapter 5). The loss of perennial grass cover resulted in the highest net positive (warming) effect, mostly due to reduced root biomass. Additionally, shrub encroachment into all patches lowered albedo, but led to negative (cooling) effects from shrub encroachment into bare ground patches due to biomass gains. This thesis challenges current views of grassy landscapes and short-duration grazing systems, emphasizing the need to rethink climate change mitigation strategies to prioritize maintaining heterogeneity, while enhancing carbon sequestration and albedo in grassy ecosystems. , Thesis (PhD) -- Faculty of Science, School of Environmental Sciences, 2024
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  • Date Issued: 2024-12

Causative factors for poor contractor performance in schools infrastructure projects

  • Authors: Baba, Vuyiseka
  • Date: 2024-12
  • Subjects: Project management , Project management -- Evaluation , School facilities -- South Africa
  • Language: English
  • Type: Master's theses , text
  • Identifier: http://hdl.handle.net/10948/68703 , vital:77083
  • Description: The public sector infrastructure departments in South Africa rely on construction companies as the major stakeholders in the implementation and maintenance of infrastructure facilities including schools. The Limpopo Province is faced with a serious challenge of underperforming contractors. This in turn affects the Provincial Government’s effective delivery of the much-needed quality infrastructure and facilities. A significant number of schools in the province are faced with infrastructure challenges including sanitation facilities, deteriorating school buildings, storm damage, inadequate infrastructure for special schools, water provision, and general maintenance. This study sought to understand the challenges faced by contractors and further explored whether the effective application of project management methodologies can have a positive impact on improving the current underperformance. Due to the nature of the study, a qualitative research method was employed to collect data. An interpretivist paradigm was adopted as the research philosophy, as it allowed for a flexible and in-depth investigation approach. The study utilized an exploratory research design. The targeted population for the study was carefully selected to obtain relevant and reliable data, and a purposive sampling technique was chosen. Semi-structured interviews were conducted as the primary data collection method, enabling the collection of first-hand information. To ensure accuracy and prevent loss of information, the research process involved recording and transcribing the interviews, using an inductive analysis approach. Eighteen out of the twenty targeted participants were successfully interviewed, resulting in a response rate of 90%. The findings of the study revealed that poor planning, inadequate financial management, inexperienced staff, interference from stakeholders, and a misunderstanding of project scope were among the many factors contributing to poor contractor performance. Furthermore, contractors, particularly Small and Medium Enterprises (SMEs), faced serious challenges during project implementation, including a lack of proper training, budget constraints, and delayed payments from clients. Based on the study's findings, it is recommended that contractors invest in planning and cost management software, including project management methodologies such as Agile, Waterfall, and MS Project. Further, contractors are encouraged to employ adequately skilled and qualified site personnel. Clients should also consider supporting underperforming contractors by pairing them with proven-performing ones to encourage mentorship and other forms of capacity building. , Thesis (MSc) -- Faculty of Engineering, the Built Environment, and Technology, School of Building and Human Settlements Management, 2024
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  • Date Issued: 2024-12

Characterization of the molecular mechanism(s) of cannabinoid-induced paraptosis in breast cancer cells

  • Authors: de la Harpe, Amy
  • Date: 2024-12
  • Subjects: Cannabinoids , Cannabinoids -- Therapeutic use , Cancer cells
  • Language: English
  • Type: Doctoral theses , text
  • Identifier: http://hdl.handle.net/10948/68818 , vital:77120
  • Description: Natural products have been extensively studied for their anticancer potential, and several widely used anticancer drugs have natural origins. Many studies have demonstrated that natural compounds can induce paraptosis in various tumour cell lines. Paraptosis is a caspase-independent cell death mechanism characterised by cytoplasmic vacuolation arising from the endoplasmic reticulum (ER) and the mitochondria. The molecular mechanism of paraptosis is unclear; however, the literature indicates that dysregulation of calcium signalling plays an important role in paraptosis induction, particularly calcium-mediated signalling between the ER and mitochondria. This study aimed to identify and characterise the mechanism of cell death induced by a phytocannabinoid ratio which induced significant cytoplasmic vacuolation in the MCF7 breast cancer cell line. Several techniques were employed to address the aim of the study. The crystal violet assay was used to detect changes in viability. Several pathway inhibitors, as well as fluorescent staining and analysis using high-content screening (HCS), were used to measure the induction of various cell death mechanisms. Morphological changes were investigated using light and transmission electron microscopy. The phytocannabinoid ratio induced significant cell death and cytoplasmic vacuolation in MCF7 cells; however, the same trend was not observed in the MCF10A non-tumourigenic breast cell line. No cell cycle arrest, apoptosis, necrosis, autophagy, or ferroptosis induction was detected in MCF7 cells, suggesting that an alternative mechanism of cell death was induced. Vacuolation and cell death induced by the phytocannabinoid ratio were inhibited by cycloheximide, suggesting a dependence on protein synthesis, which is characteristic of paraptosis induction. The mechanism of paraptosis induction by the phytocannabinoid ratio was investigated, and it was found that treatment 1) induced ER dilation and mitochondrial swelling; 2) induced significant ER stress, mitochondrial calcium overload, and mitochondrial dysfunction which appeared to be mediated by the voltage-dependent anion channel (VDAC); and 3) significantly impaired all mitochondrial metabolic pathways. Overall, the data demonstrated that paraptosis induced by the cannabinoid ratio is mediated by calcium flux from the ER to the mitochondria. This highlighted a novel mechanism of phytocannabinoid-induced cell death and emphasised the anti-cancer potential of the use of phytocannabinoid ratios as opposed to individual phytocannabinoids, expanding their potential for use as anticancer agents. , Thesis (PhD) -- Faculty of Science, School of Biomolecular & Chemical Sciences, 2024
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  • Date Issued: 2024-12

Co-generated learnings from hopes-an NRF grant funded university engagement project

  • Authors: Quvile, Xola Bulumko
  • Date: 2024-12
  • Subjects: National Research Foundation (South Africa) , Research grants -- South Africa , Education, Higher -- South Africa
  • Language: English
  • Type: Master's theses , text
  • Identifier: http://hdl.handle.net/10948/68366 , vital:76990
  • Description: The study had sought to understand the systemic and individual factors that facilitated or inhibited the NRF grant-funded HOPES Project. HOPES collaborated with the Centre for the Community School in the Faculty of Education, and various communities of practice (COPs) in existing school communities in the Eastern Cape Province of South Africa. The project applied a critical participatory action research work to develop a framework for school improvement and in the process contribute to making schools beacons of hope. This research provides insights into how an NRF community engagement grant project team (HOPES) navigated external and internal factors such as COVID-19, rules regulating the grant, and multiple realities of the stakeholders at play. The study was qualitative and used the critical participatory action research design. The study purposively and conveniently sampled seven HOPES Project team members to collect data via focus groups and individual interviews and collected secondary data from NRF HOPES annual project reports. The study findings improved the participants' understanding of their journey, and the co-generated knowledge shed light on how NFR and community engagement grant funders could promote enabling conditions towards achieving individual scholars and collective project outcomes. The study findings provide learnings for the Faculty of Education and the Nelson Mandela University on how extrinsic and intrinsic enablers and barriers can be addressed to optimise a project of this nature. , Thesis (MEd) -- Faculty of Education, School of Postgraduate Education, 2024
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  • Date Issued: 2024-12

Collaborative conservation governance in multifunctional landscapes: a contextual analysis of two South African biosphere reserves in the Boland

  • Authors: Klaver, Michael
  • Date: 2024-12
  • Subjects: Unesco -- Programme on Man and the Biosphere , Nature conservation -- South Africa , Biosphere
  • Language: English
  • Type: Master's theses , text
  • Identifier: http://hdl.handle.net/10948/68924 , vital:77164
  • Description: The Man and the Biosphere Programme (MAB) has been earmarked as one of the most promising ways of tackling the grand challenges of our time and achieving the Sustainable Development Goals. Furthermore, it may have the potential to make positive contributions to one of the most troubling conservation challenges of our time – winning spaces for large carnivores in human-dominated landscapes. This study aims to assess the interpretation and implementation of MAB in two South African Biosphere Reserves (BRs) and explore how BRs as landscape level collaborative initiatives can support Cape leopard conservation in the Boland region of the Western Cape, South Africa. This study is informed by two objectives. First, to understand how the chosen governance strategy and structure of two South African BRs have helped to achieve a context appropriate interpretation and actioning of MAB in the landscape. Second, to understand how landscape-level collaborative conservation initiatives support leopard conservation across a multifunctional landscape. This study takes on a mixed methods approach in which qualitative data takes priority and quantitative data is used for support in an embedded multiple-case study design. The sampling techniques used include purposive sampling of strategically targeted participants, i.e. those governing BRs and those leading the collaborative initiative and snowballing thereon. Data collection included a combination of semi-structure interviews (n=20) (the principal collection method), a review of archival, policy and other documents (n=15), and supported by a mixed methods survey questionnaire (n=5). Data were analysed through thematic and content analysis. Findings suggest that organisations working at a landscape-level utilise forms of adaptive co-management and/or governance as a means to being both adaptive and collaborative. Important themes which emerge include cross-sectoral approaches, networks, leadership and trust for building partnerships, shared visions and ‘filling gaps’ left by, or collaborating with the state to fulfil mutually beneficial objectives. This research provides empirical studies on MAB, important for sharing knowledge across the World Network of BRs, meeting the need for further research on collaborative initiatives in social-ecological systems and conservation programmes for large free-roaming carnivores in multifunctional landscapes. , Thesis (MSc) -- Faculty of Science, School of Natural Resource Science & Management, 2024
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  • Date Issued: 2024-12

Comparative study of the effect of iloprost on neuroinflammatory changes in c8-b4 microglial cells and murine model of trypanosomiasis

  • Authors: Jacobs, Ashleigh
  • Date: 2024-12
  • Subjects: Neuroimmunology , DNA -- Methylation , Nervous system -- Degeneration
  • Language: English
  • Type: Master's theses , text
  • Identifier: http://hdl.handle.net/10948/68895 , vital:77160
  • Description: Neurodegenerative conditions significantly impact well-being and quality of life in individuals with major symptoms including mood disorders, cognitive decline, and psychiatric disturbances, often resulting from neuroinflammation triggered by immune responses to bacterial or parasitic infections such as gram-negative bacteria or Human African Trypanosomiasis. Microglia play a crucial role in both neurotoxicity and cellular processes involved in restoring the neural health. Exploring the therapeutic potential of prostacyclin and its analogues in regulating microglia responses to inflammatory insult and treating Trypanosoma brucei (T.b) infection remains an unexplored area. The aim of this study was to assess the potential neuroprotective effects of Iloprost through comparative analysis of neuroinflammatory responses in both microglial cells exposed to lipopolysaccharide (LPS) and mouse brains infected with T.b brucei. In phase I of this study both resting and LPS treated C8-B4 microglial cells were exposed to varying concentrations of Iloprost. The effects of Iloprost on LPS-induced inflammation were analysed using immunofluorescence to detect microglial activation and differentiate between pro and anti-inflammatory phenotypes. Furthermore, pro and anti-inflammatory cytokine secretion was determined using an ELISA, in addition gene expression analysis was carried out using quantitative polymerase chain reaction (qPCR). Also, DNA methylation status of C8-B4 cells exposed to LPS challenge alone or in combination with various concentrations of Iloprost were determined using bisulfite sequencing technique followed by qPCR. In phase II of the study, a total of twenty-four Albino Swiss male mice (8-10 weeks old) were divided into four treatment groups with 6 mice in each group. All treatment groups except the non-infected control were inoculated with the T.b brucei parasite. One group received a single intraperitoneal injection of Diminazene aceturate (4 mg kg-1)while the remaining group received repeated intraperitoneal injections of Iloprost (200 μg kg-1). On day ten of the study, mouse brains were removed on ice using forceps. The hippocampal tissues were dissected out and processed for quantification of gene expression changes in pro and anti-inflammatory cytokines. Overall, the findings of this study indicate that LPS-induced pro-inflammatory cytokine, TNF-α and IL-1β, secretion and gene expression is down-regulated in C8-B4 microglial cells treated with Iloprost. Furthermore, there was a significant up-regulation in the expression of anti-inflammatory genes, particularly ARG-1, CD206, BDNF and CREB in response to Iloprost treatment following LPS-induced inflammation. This study is also the first to confirm M2 microglial polarization with Iloprost treatment in both resting and LPS treated cells. However, hypermethylation at CREB and BDNF promoter regions was observed 24 hours after Iloprost treatment. Additionally, Iloprost reversed hypomethylation at the BDNF promoter region that had been induced by LPS treatment. The rodent model also indicated a downregulation in the pro-inflammatory cytokine, IL-1β, expression and upregulation of BDNF transcription in T.b brucei infected mice treated with repeated doses of Iloprost. In conclusion, determining the immunomodulatory roles of Iloprost in both in vitro and in vivo models of neuroinflammation could assist in the development of alternative therapy for neurodegenerative disease. , Thesis (MSc) -- Faculty of Science, School of Biomolecular & Chemical Sciences, 2024
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  • Date Issued: 2024-12

Construction material waste control success model for the construction industry

  • Authors: Musah, Abdul Razak
  • Date: 2024-12
  • Subjects: Construction industry -- Materials management , Construction industry -- Management , Construction industry -- Environmental aspects
  • Language: English
  • Type: Doctoral theses , text
  • Identifier: http://hdl.handle.net/10948/68796 , vital:77114
  • Description: Economic sustainability and reconstruction in many economies rely heavily on the construction sector and remain strategic tools for governments and industries worldwide. Excessive construction costs and materials waste among some construction companies are rampant in the construction sector. Most of this waste is poorly managed, thus triggering significant project failure problems, leading to the project stakeholders losing the value of their investment. This concern advocate for effective control of construction material to avoid wastage. The primary objective of this study was to develop a Construction Waste Material Control (CWMC) model to be used by construction project professionals throughout the Project Management (PM) phases: initiation, planning, execution, monitoring, control and closure. Significant literature on construction materials waste, Project Management (PM) processes, and project performance regarding poor waste management and project failure was reviewed. This literature review was conducted to identify factors affecting Construction Waste Material Control (CWMC). These factors were identified and defined together with their respective contributions to the model. A quantitative survey instrument (questionnaire) was used to obtain information from construction sector professionals. A total of 213 questionnaire were received and administered for the study. Structural Equation Model (SEM) SEM was used to analyse the questionnaire data, and thereby assisting the research to clearly define latent constructs statistically significant to the (CWMC) model. The finding was that, the factors identified to have impact on CWMC are Project Initiation Phase Tools (PIPTs), Project Planning Phase Tools (PPPTs), project failure/success factors (PFFs), Project Execution Phase Tools (PEPTs), Project Monitoring and Control Phase Tools (PMCPTs), Construction waste material Control (CWMC) policy and Project Management (PM) competence. The supported hypotheses also authenticated these factors. Introducing the model into the construction sector provides another dimension to CWMC. By establishing the aforementioned factors, the model gives construction professionals precise CWMC predictive accuracy. As the model reliability test of 0.734 to 0.972 satisfied the theoretical threshold and goodness of fit of 0.912 of Normed fit index respectively. The model is the first of its kind and contributes significantly to the construction sector’s existing body of knowledge. , Thesis (PhD) -- Faculty of Engineering, the Built Environment, and Technology, School of Built Environment and Civil Engineering, 2024
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  • Date Issued: 2024-12

Development of density-dependent and density-independent competition models to understand single tree growth responses in eucalyptus stands

  • Authors: Kepe, Lulama Patrick
  • Date: 2024-12
  • Subjects: Forests and forestry -- Mathematical models , Trees -- Growth -- Mathematical models , Eucalyptus grandis
  • Language: English
  • Type: Doctoral theses , text
  • Identifier: http://hdl.handle.net/10948/68906 , vital:77161
  • Description: In commercial forest production, predicted yields based on mensuration recommendations are seldom realized, and minimal silvicultural standards based on results from trial blocks do not account for the relationship between initial planting density and final stocking. Growth models designed to investigate management options must employ competition indices to provide reliable predictions under extreme silviculture. The competition a tree experiences until the day of harvest is a strong driver for quality and volume of timber. Hence, this turns the regulation of competition into an integral part of silviculture. According to Little et al. (2003), it is known that, at some stage after canopy closure, individual trees in a stand will begin to compete for resources. To investigate competition amongst individual trees, a re-purposed Bayesian mixed effects model, similar in characteristics to a Sire model used for estimating breeding values, is proposed. In animal breeding models, the Sire Model allows for the inclusion of a numerator relationship matrix containing inbreeding coefficients. In a similar way, documented competition indices are included in the model in an attempt to estimate posterior probabilities of specifically selected individual trees being the strongest growers during different stages in the tree growth cycle. Estimated tree growth indices were determined and used to make probability statements in order to rank the individually selected trees based on the amount of growth observed. A tree growth index is a measurement of a tree’s average growth performance in relation to the average growth performance of all trees on the same plot. As different competition indices are introduced into the model, changes in the probabilities are observed and compared to what is visually observed on the plot, i.e. if the tree with the highest probability of being the strongest grower, is actually not necessarily the largest tree of the group of selected trees, but rather the tree that presented the largest amount of growth of the selected group of trees during that specific growth season. From a randomly selected plot, a group of neighboring trees were randomly selected. Four specifically selected target trees were then identified from this group of 25 selected trees, and analyzed. For this discussion, for example, from our randomly selected group of 25 neighboring trees, tree 54, tree 56, tree 86, and tree 88 were specifically selected for further analysis. For these specifically selected trees, marginal posterior densities for the variance components and random effects were then estimated using the Gibbs Sampler, where competition between the trees was assumed present, as well as for the case where it was assumed that no competition takes place between the individually selected trees. In the latter case, an identity matrix was utilized in the Gibbs sampling algorithm where it was assumed that there is no competition between the trees. Both a distance independent competition index (Lorimer,1983), and a distance dependent index (Hegyi, 1974), were used to generate the numerator relationship matrix A that was used by the Gibbs sampling algorithm in the case where competition was assumed between individual trees. Also a new distance dependent index was proposed and tested in this study as well. Results from the selected plot, with a 1500 stems per hectare (sph) density, indicated that there were no significant differences in the average growth between these selected trees. However, the marginal posterior densities of the fixed effects indicated that there was a significant difference in the average growth rates between the base level conditions and other levels determined for each of these fixed effect factors for the selected trees, since their 95% equal tails credibility intervals, did not contain zero. This therefore indicated that the specific treatment applied on the plot, had a significant effect on the individual tree growth. Results when competition was assumed present, revealed that the estimated marginal posterior densities for the error variance as well as tree variance, were severely positively skewed. , Thesis (PhD) -- Faculty of Science, School of Natural Resource Science & Management, 2024
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  • Date Issued: 2024-12

Exploiting continuous flow technology to develop synthetic processes for active pharmaceutical ingredients: prilocaine and betrixaban

  • Authors: Sagandira, Mellisa Brenda
  • Date: 2024-12
  • Subjects: Pharmaceutical technology , Drug development , Pharmaceutical biotechnology
  • Language: English
  • Type: Doctoral theses , text
  • Identifier: http://hdl.handle.net/10948/69464 , vital:77259
  • Description: The dilemma of providing affordable health care has long haunted African countries due to the continuously growing disease burden as the population increases. Africa accounts for only 3 % of global drug production and imports over 90 % of its life saving medicines at a yearly cost of US$14 billion according to the African Development Bank (AfDB). Attaining Africa’s Agenda 2063, Universal Health Coverage (UHC) and Sustainable development Goal 3 (SDG3) aspirations of ensuring healthy and well-nourished citizens remain difficult given this situation. This over-dependence on imports has led to drug shortages, high pricing, poor quality medicines and unguaranteed supply chains, thus there still remains an unmet need. The advent of the COVID-19 pandemic worsened this situation as many countries curbed exports resulting in a crisis across the continent. Africa experienced high demand of medicines compared to prepandemic level, which threatened the health care of the continent. This situation can be addressed by establishment of local pharmaceutical manufacturing capability through adoption of advanced manufacturing technologies such as continuous flow chemistry. In this research, we therefore seek to exploit continuous flow chemistry, an enabling technology to develop safe and efficient synthetic processes for active pharmaceutical ingredients: prilocaine and betrixaban as case studies. To the best of our knowledge there is no reported work on synthetic processes towards prilocaine and betrixaban under continuous flow conditions, thus this research extensively unearthed interesting continuous flow processes towards these APIs. In a broader view, establishment of local APIs production will ease Africa’s over-dependence on imports, which will in turn address issues such as drug shortages, poor quality and high pricing. This work aims to demonstrate how continuous flow technology can be useful for the establishment of local APIs manufacturing, which will inherently revolutionize medicines availability, affordability and accessibility to the greater population. Chapter one begins with a brief overview on Africa’s disease burden and pharmaceutical supply chain. Continuous flow chemistry is introduced with its benefits and limitations discussed. Lastly a mini review of examples of APIs synthesised in continuous flow is presented. In chapter two, we demonstrate how continuous flow technology can be exploited to develop synthetic processes towards prilocaine as our first case study. This chapter clearly demonstrates how highly exothermic nitration reactions can be safely handled by using continuous flow systems. Additionally, the use of a micro structured mixer facilitated biphasic nitration of toluene to be carried out with enhanced mass transfer, which inherently led to improved selectivity of ortho-nitrotoluene (preferred isomer) to 79 % compared to 59 % achieved in batch mode. A two-step synthesis of ortho-toluidine via biphasic nitration of toluene and nitroreduction was demonstrated with the incorporation of a Zaiput liquid/liquid separator to facilitate in-line separation. Comprehensive optimisation studies were carried out in flow. Prilocaine was synthesised in 74 % overall yield in a 13.6 min residence time for all processes. In chapter three, we demonstrate how continuous flow technology can be exploited to develop synthetic processes towards betrixaban. Synthetic routes towards betrixaban feature two amide bond formation transformations. Pleasingly, we explored multistep chemistry to develop amide synthesis protocols in flow without interruption for work up and isolation. An overall yield of 92 % was achieved to get to key intermediate to betrixaban in 8 min total residence time. Chapter four demonstrates the robustness of developed amide synthesis protocols, a key transformation in synthetic routes towards prilocaine and betrixaban in continuous flow systems. A total of 22 amides were synthesised via flow multistep processes with isolated yields greater than 82 %. All the compounds were characterized using infrared spectroscopy (IR), and nuclear magnetic resonance (NMR). Quantification of the reaction mixtures were carried out using highperformance liquid chromatography (HPLC) and gas chromatography (GC). , Thesis (PhD) -- Faculty of Science, School of Biomolecular & Chemical Sciences, 2024
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  • Date Issued: 2024-12

Exploring children’s understandings of gender using critical literacy in a reading club

  • Authors: Jansen, Lincoln Lee , Surname, name
  • Date: 2024-12
  • Subjects: Book clubs (Discussion groups) -- South Africa , Literacy -- Study and teaching (Elementary) , Literacy -- Study and teaching (Middle school)
  • Language: English
  • Type: Doctoral theses , text
  • Identifier: http://hdl.handle.net/10948/68333 , vital:76976
  • Description: School literacy practices have always favoured traditional, gender stereotypical portrayals of characters in books. These portrayals are not troublesome as it helps children build a sense of identity. However, these portrayals often fail to represent people in more diverse ways and thus does not reflect how societies have progressed. These narrow portrayals are also often limiting and do not take into consideration people’s personal interests which can lead to them being ostracised and marginalised. The People’s Republic of China is the context for this study where traditional, conservative views are upheld about ways of being and doing for males and females. This is a qualitative study within the interpretivist paradigm which recognised the individual perceptions of participants within their specific sociocultural context. By establishing a reading club as a Third Space for literacy engagement, this study sought to explore how grade 2 learners at a school in Beijing, China responded to traditional and diverse portrayals of characters in books. This study regarded the establishment of a reading club as an empowering practice as it allowed a safe space for the participants to freely share their deliberations about ways of being in the world. Coupled with critical literacy as a practice, participants took a critical stance in instances of gender bias and injustices and in doing so, allowed them to accentuate their morality. Findings of this study suggest that the Chinese participants had very flexible ideas about ways of being and doing in the world as long as these did not conflict with their understandings of the law. Participants also upheld that gender performances and gendered behaviour are open to all with impunity. The findings of this study also highlight the importance of providing diverse literature to children as this helps them to deal with, and examine, issues they might not ordinarily encounter in a safe way and in doing so, expand their worldviews and cultivate empathy. , Thesis (PhD) -- Faculty of Education, School of Primary Schooling, 2024
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  • Date Issued: 2024-12

Formulation of Fish Feed for Aquaculture using Olive Pomace Extract as an Antioxidant

  • Authors: Koza, Nondumiso Norma
  • Date: 2024-12
  • Subjects: Fishes -- Feeding and feeds , Fishes -- Ecology , Sustainable aquaculture
  • Language: English
  • Type: Master's theses , text
  • Identifier: http://hdl.handle.net/10948/69318 , vital:77205
  • Description: Olive pomace is a significant by-product of the olive oil extraction process and is an environmental issue in olive-producing countries. This project aimed to add extracts from olive pomace as an antioxidant to a fish feed formulation without compromising growth performance and meat quality, thereby contributing to the aquaculture industry. To produce the olive pomace extracts, Coratina cultivar olives were collected from a farm near Oudtshoorn, and the fresh pomace was immediately frozen at -22oC for preservation. The extracts were obtained using a large-scale extraction method using a solvent blend of n-heptane, ethanol, and water. A pressure filtration and centrifuge method were then applied to separate any residue from the extracts. An HPLC method was developed to characterise the extracts' content, identifying various bioactive compounds such as squalene, α-tocopherol, and water-soluble polyphenols like oleuropein, hydroxytyrosol, and tyrosol. In a fish feeding trial it was concluded that the fish fed with the feed without olive pomace gained more weight than those fed the feed with the added pomace extract. Overall, the results indicate that fish sustained on the feed without the olive pomace extract ate more food, consuming more energy to support weight gain but that this did not necessarily translate to an improved feed conversion ratio. The morphometric variables suggest that fish used in the trial remained healthy, implying that there may be a taste or palatability difference between feeds that could explain why less of the feed with olive pomace extract was eaten. Overall, the observed feed conversion ratio values were somewhat lower than the expected values for tilapia (FCR: 1.5-2.0). The peroxide value of fish feed with an addition of 0.3% olive pomace extract was lower than that of the feed without olive pomace extract after 12 weeks of stability testing at room temperature. The results showed a value of 1.48 MeqO2/kg for the feed containing olive pomace extract compared to the peroxide value for the fish feed without olive pomace extract, which was 2.75 MeqO2/kg. This indicates that the nutritional content of the feed was preserved. , Thesis (MSc) -- Faculty of Science, School of Biomolecular & Chemical Sciences, 2024
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  • Date Issued: 2024-12

Graphene@microalgae-based nanohybrid structures as adsorbents for removal of Cr(VI) ions in aqueous solutions

  • Authors: Mulovhedzi, Rolivhuwa
  • Date: 2024-12
  • Subjects: Nanoscience , Nanotechnology , Nonaqueous solvents
  • Language: English
  • Type: Master's theses , text
  • Identifier: http://hdl.handle.net/10948/69404 , vital:77252
  • Description: iv ABSTRACT The efficient removal of heavy metals using carbon-based nanoadsorbents poses a substantial challenge in the domain of water purification. Graphene-based materials have been extensively utilised in the treatment of water and wastewater due to their tremendous surface areas, porosity, turntable nature to different functional groups, and photo-catalytic properties. In this project, graphene oxide (GO) was synthesised via the modified Hummers method. A similar method was used to produce nitrogen-doped graphene oxide (NGO), with urea as the nitrogen precursor. Utilising biomass materials to dope graphene-based nanocomposites can effectively enhance their application in water treatment. In this work, graphene oxide-microalgae (GO@Algae) and N-doped graphene oxide-microalgae (NGO@Algae) nanocomposites were synthesised by combining GO or NGO with green Scenedesmus microalgae. This was done through a solution self-assembly mixing method using ultrasonication. The resulting nanocomposites were used to remove Cr(VI) from water solutions. The influence of microalgae content deposited on GO and NGO nanosheets at different weight ratios (1:1, 3:1, and 1:3) on the chemical, structural, morphological, and thermal characteristics of nanoadsorbents was evaluated using various techniques such as Brunauer-Emmett-Teller (BET), scanning electron microscopy (SEM), thermogravimetric analysis (TGA), Fourier Transform Infrared Spectroscopy (FT-IR), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). The flat nanosheet-like morphology of GO@Algae and NGO@Algae nanostructured materials was observed through SEM, confirming microalgae's incorporation within the GO and NGO matrices. The thermal stability and surface area properties of GO and NGO nanocomposite materials decreased with the incorporation of microalgae content. The incorporation of microalgae into GO nanosheets showed enhancements in chemical and structural properties due to the presence of the strong covalent interaction (oxygen and nitrogen-containing groups) between the interfaces of nanocomposites. XPS and FT-IR analyses revealed the existence of amides, carboxylic acids, and phosphates, which exhibited positive charges below the pH 2.03 point-of-zero charge. The second phase of the study involved assessing the adsorption capabilities of the GO, NGO nanosheets, and GO@Algae and NGO@Algae nanocomposites in removing Cr(VI)from the water solution. Adsorption parameters such as the effect of solution pH, contact time, adsorbent dosage and metal ion concentrations were evaluated for Cr(VI) removal. When comparing GO, NGO, GO@Algae, and NGO@Algae, it was found that GO@Algae and NGO@Algae exhibited superior adsorption performance due to the available functional groups and well-developed pores. Additionally, a mixed ratio of GO or NGO and algae at a ratio of 1:3 was found to be the most suitable for GO@Algae and NGO@Algae. The adsorption efficiency of nanostructured materials for Cr(VI) is significantly influenced by their surface charge, porosity and specific surface area. The results revealed that the adsorption capabilities of GO@Algae (1:3) and NGO@Algae (1:3) were 2.24 and 2.01 times higher than GO and NGO which were 1.64 and 1.89, respectively, at a solution of pH 2 where HCrO4− species are predominant compared to a solution of pH 5 which predominate a mix of Cr2O72− and CrO42- species. The enhanced performance of the GO@Algae and NGO@Algae nanocomposites is attributed due to their increased surface functionalities and porosity. The adsorption of Cr(VI) ions by the GO/NGO@Algae nanocomposites declined with increasing initial concentration of Cr(VI) species in the water medium. The adsorption kinetics data for GO, NGO, GO@Algae (1:3), and NGO@Algae (1:3) exhibited a good fit with the pseudo-second-order model (R2 > 0.995) suggesting that chemisorption governed the adsorption process. Similarly, the isotherm adsorption findings showed a good fit with the Freundlich model (R2 > 0.961). The findings indicated that the adsorption mechanism process was characterised by monolayer adsorption onto a heterogeneous adsorbent surface. Furthermore, the GO@Algae (1:3) was found to have the maximum adsorption capacity of 10.85 mg/g surpassing the capacities of both unmodified and NGO@Algae counterparts. The application of GO@Algae and NGO@Algae has the potential to promote the green reuse of graphene-based nanomaterials. In summary, GO@Algae and NGO@Algae show great potential as eco-friendly adsorbents for the feasible treatment of heavy metal-contaminated water. , Thesis (MSc) -- Faculty of Science, School of Biomolecular & Chemical Sciences, 2024
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  • Date Issued: 2024-12

Ground- and marine water inputs into supratidal microbialite systems along the Nelson Mandela Bay coastline

  • Authors: O’Connell, Tristin Wade
  • Date: 2024-12
  • Subjects: Groundwater -- South Africa -- Nelson Mandela Bay , Earth sciences , Geology
  • Language: English
  • Type: Master's theses , text
  • Identifier: http://hdl.handle.net/10948/69415 , vital:77253
  • Description: Extant supratidal microbialite systems are especially numerous and well-developed along the rocky coastline of Nelson Mandela Bay (NMB), South Africa. Precipitating in a hydrological environment formed by the input of constant, fresh groundwater discharge and periodic marine water intrusion these systems form part of the longest uninterrupted geological record of life on Earth (~3.4 billion years ago). Microbialites are layered organosedimentary deposits which potentially provide a window into historical environmental conditions. This study focusses on the fresh groundwater and saline marine water inputs of these microbialite pools, and the corresponding microbialite accretion rates. Severe regional drought in the NMB area resulted in rapid anthropogenic groundwater abstraction of the coastal aquifers on which the microbialite systems rely for groundwater inflow. This study provides insight into the current state of the coastal aquifers of NMB through the quantification of groundwater discharge via microbialite systems in terms of volume and flow rate. This is paired with in situ hourly microbialite pool water temperature and conductivity data to determine the effect of marine intrusion and the role of tidal flushing in these pools. A spatial assessment of groundwater discharge conducted using quantitative and semi-quantitative measurement techniques indicated that the total discharge of the study area is ~45.8 L/s or 3.8 ML/d. Over 1,500 freshwater seeps were identified, of which 78% showed microbialite deposits. Topography of the coast indicated that this might influence the flowrate. Calcareous sediment of sandy beaches within the study area supported lower discharge, while rocky shores with lithified rock had higher discharge. Seasonal differences in the volume discharged were evident, with winter having higher flowrates. Flow paths and discharge rates are affected by inland lithological differences and indicate variability linked to rainfall events that show lag effects depending on aquifer origins. This study is the first spatial analysis of the volume of groundwater discharging through microbialite-fed seeps. Marine intrusion and the corresponding pool flushing dynamics identified three types of microbailite systems: groundwater-dominant, dynamic input, and fast-reacting sites. A novel measurement technique for microbialite accretion determined accretion rates for systems under varying pool conditions. Although the average accretion rates of the Nelson Mandela Bay microbialites were in the order of erosion of 0.35 mm per year, there was significant variability in these measurements likely linked to differential localised vulnerability to storm events or responses to groundwater ix flow variability. It remains to be determined whether these factors are definitive risks to the sensitive supratidal microbialite systems. , Thesis (MSc) -- Faculty of Science, School of Environmental Sciences, 2024
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  • Date Issued: 2024-12

Gymnopilus junonius and Rhodofomitopsis lilacinogilva: In vitro evaluation of antimycobacterial activity, safety assessment and isolation of active compounds

  • Authors: Didloff, Jenske
  • Date: 2024-12
  • Subjects: Antibacterial agents , Plants, Useful -- South Africa , Medicinal plants -- South Africa
  • Language: English
  • Type: Doctoral theses , text
  • Identifier: http://hdl.handle.net/10948/68840 , vital:77122
  • Description: Tuberculosis remains a significant public health challenge due to the complexity and compliance issues of its treatment, the prevalence of latent infections, the high rate of HIV co-infection, and the spread of drug-resistant strains. This highlights the need to search for new antimycobacterial drugs. Natural products have historically been used as sources for the discovery of pharmaceuticals. Although medicinal macrofungi have been exploited in traditional folk medicines for the treatment of various diseases, research into their antimycobacterial activity remains limited.The aim of this study was to isolate, identify, and characterise the antimycobacterial compound(s) present in ethanol fruiting body extracts of Gymnopilus junonius (Fr.) P.D. Orton (Hymenogastraceae) and Rhodofomitopsis lilacinogilva (Berk.) B.K. Cui, M.L. Han, & Y.C. Dai (Fomitopsidaceae), as well as to investigate their mechanism of action and potential toxicity using in vitro and in vivo screening methods.Bioassay-guided fractionation was conducted using column chromatography and preparative thin-layer chromatography to isolate the active antimycobacterial fraction/compound from ethanol extracts of G. junonius and R. lilacinogilva. Antimycobacterial activity against M. tuberculosis H37Rv was screened using a resazurin microplate assay (REMA). The chemical structure was elucidated employing 1D-(1H NMR) and 2D NMR spectroscopy (HSQC, HMBC) techniques, along with High- Performance Liquid Chromatography High-Resolution Electron Spray Ionisation Mass Spectrometry (HPLC-HRESI-MS). Transmission electron microscopy (TEM) was utilised to observe the ultrastructural changes in M. tuberculosis induced by the active fraction/compound. Toxicity assessment was performed on African green monkeykidney (Vero) and human hepatoma (C3A) cell lines using various staining techniques to observe the potential risk for hepatotoxicity (CellRox orange, TMRE, and MTG staining) and genotoxicity (NucRed staining). In vivo toxicity of extracts was evaluated using a zebrafish embryo/larvae model to observe developmental and teratogenic effects.The bioassay-guided fractionation of G. junonius and R. lilacinogilva extracts yielded an active compound and a fraction displaying inhibitory activity against M. tuberculosis, with MIC values of 31.25 μg/mL and 250 μg/mL, respectively. Gymnopilene was identified as the main active compound isolated from G. junonius, while fraction 8 from R. lilacinogilva contained a predominant constituent resembling a pachymic acid derivative. Transmission electron microscopy revealed ultrastructural damage to M. tuberculosis cells upon treatment with gymnopilene and fraction 8, which was observed as the disruption and disintegration of the cell wall. In vitro toxicity assessment indicated a reduction in the cell density in both Vero and C3A cell lines following exposure to the fractions/gymnopilene. Although there were no significant alterations in the production of reactive oxygen species, changes in mitochondrial dynamics were observed. Genotoxic assessment showed no significant changes. In vivo toxicity assessment showed no significant effects for G. junonius against the zebrafish embryos/larvae, whereas R. lilacinogilva remained toxic and induced developmental abnormalities over a 72-hour time period.The findings of this study highlight the potential of macrofungi as a valuable source of bioactive compounds, confirming the significance of natural products in drug discovery. Notably, this research represents the first to demonstrate that the predominant compound, gymnopilene, isolated from G. junonius exhibits inhibitory activity against M. tuberculosis, contributing to the novelty of the study. Furthermore, the study expands our understanding of the antimycobacterial properties of the selected macrofungal species, G. junonius and R. lilacinogilva, by demonstrating the ultrastructural damage to M. tuberculosis cell wall induced by treatment. However, it is important to recognise the potential toxicity identified through in vitro and/or in vivo screening assays. The observed toxicity may hamper their suitability formdrug development. Future investigations could explore the inclusion of additional in vitro based models, perhaps more complex and physiologically relevant models alongside the in vivo screening model to assess the therapeutic potential of isolated fractions/compounds. , Thesis (PhD) -- Faculty of Science, School of Biomolecular & Chemical Sciences, 2024
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  • Date Issued: 2024-12
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