From Clown Prince to critical phenomenon: Fashioning the Joker as a nomadic war machine
- Authors: Goldmann, Talya
- Date: 2024-04
- Subjects: Joker -- (Fictitious character) , Comic books, strips, etc. -- United States -- History and criticism , Literature and society -- United States
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10948/62769 , vital:72941
- Description: Based on the original clown prince of crime in the DC comic books, the Joker is one of the most notorious villains in cinematic history. He originated in the comic book Batman #1 (Finger, 1940) over eighty years ago, and he remains a prominent character across a myriad of media platforms. In film and television, the Joker has appeared in major and minor roles in approximately nine animated series, eighteen animated films, six live-action series, and five live-action films. Indeed, multiple roles, actors, and decades after the character’s first debut in the Batman television series (1966), the Joker continues to be well-received and sought-after, insofar as every time a new Joker is announced, the character garners more intensive publicity and the film as a whole becomes highly anticipated. Thus, what started as a simple clownish character in the role of a minor villain in Batman (1966), has evolved into a multi-faceted villain so captivating that he has recently earned his own stand-alone films, namely Todd Phillips’ Joker (2019), and the sequel, Joker Folie à Deux (2024) – where he is no longer the antagonist, but now the protagonist. In this research, firstly, key features of the Deleuzoguattarian schema relevant to this study will be presented, before capitalism – as the context of Batman’s Gotham – is considered through a Deleuzoguattarian lens. This study will delve into what makes the beloved Joker so extraordinary along with the aesthetic features associated with his meteoric rise to fame. In this regard, what will be theorized is that the Joker constitutes an example of a Deleuzean nomadic war machine: that is, a critical character who borrows aspects of the State Apparatus and then twists and shapes them into weapons through which he questions and mocks society for its authoritarian and ideological flaws, and with which he exposes its conceptual and ethical blind spots. In this way, he acts like a mirror, reflecting what is wrong with society, and by implication, with the human ‘nature’ – not only in the fictional world of Gotham, but also in the contemporary era created therein. More specifically, discourse analysis and film analysis will be used here, to engage critically with the Joker’s persona in relation to the changing contexts in which the various films were made, in order to trace the development of the character through a Deleuzoguattarian lens. As will be discussed, Phillips’ Joker (2019) signals the deterritorialization of the Joker from the ambit of Batman’s influence, and opens up the possibility for his further deterritorialization as an increasingly mobile and nomadic catalyst of critical thinking beyond even Gotham itself. Then, thirdly, an in-depth analysis on the five key cinematic Jokers will be completed in terms of the characters’ historical contexts, character backgrounds, and aesthetics. And thereafter, the deterritorializing ‘line of flight’ already underway – as by Phillips’ Joker (2019) – will be continued through the creative media production component of this study, which will entail the conceptualization, design and illustration of three new Joker manifestations, each of which will reflect critically upon failing systems in South African society across select time periods, and how these failing systems have contributed to the collective trauma of marginalized groups of people. The first South African Joker manifestation, set in the 1980s, will reflect upon the faltering political infrastructure during the Apartheid era. The second Joker manifestation, set in the early 2000s, will encapsulate the repercussions of the post-Apartheid neoliberal economic landscape. And the third Joker manifestation, set in the 2010s, will draw attention to sociocultural collapse particularly in the space of gender-based violence and sexual assault. Thus, the creation of these Jokers will act as an exploration of trauma, insofar as the tragedy and pain caused by the above-mentioned failing systems will manifest physically through their character designs. In terms of this, and in keeping with the dynamics of appropriation and inflection that are definitive of nomadic war machines, here focus will fall on how their character aesthetics pose critical questions about relevant issues in the South Africa. On account of this, although this research is by definition situated within the spectacle/performance paradigm, it also runs counter to the largely apolitical orientation of creative media production that occurs therein, through its emphasis, instead, on how such creative media production can also entail critical thought that is aimed at thematizing socio-cultural and politico-economic issues and the trauma that they create; thus, this creative media component aims to encourage a more trauma-aware society through art. , Thesis (MA) -- Faculty of Humanities, School of Language, Media and Communication, 2023
- Full Text:
- Date Issued: 2024-04
- Authors: Goldmann, Talya
- Date: 2024-04
- Subjects: Joker -- (Fictitious character) , Comic books, strips, etc. -- United States -- History and criticism , Literature and society -- United States
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10948/62769 , vital:72941
- Description: Based on the original clown prince of crime in the DC comic books, the Joker is one of the most notorious villains in cinematic history. He originated in the comic book Batman #1 (Finger, 1940) over eighty years ago, and he remains a prominent character across a myriad of media platforms. In film and television, the Joker has appeared in major and minor roles in approximately nine animated series, eighteen animated films, six live-action series, and five live-action films. Indeed, multiple roles, actors, and decades after the character’s first debut in the Batman television series (1966), the Joker continues to be well-received and sought-after, insofar as every time a new Joker is announced, the character garners more intensive publicity and the film as a whole becomes highly anticipated. Thus, what started as a simple clownish character in the role of a minor villain in Batman (1966), has evolved into a multi-faceted villain so captivating that he has recently earned his own stand-alone films, namely Todd Phillips’ Joker (2019), and the sequel, Joker Folie à Deux (2024) – where he is no longer the antagonist, but now the protagonist. In this research, firstly, key features of the Deleuzoguattarian schema relevant to this study will be presented, before capitalism – as the context of Batman’s Gotham – is considered through a Deleuzoguattarian lens. This study will delve into what makes the beloved Joker so extraordinary along with the aesthetic features associated with his meteoric rise to fame. In this regard, what will be theorized is that the Joker constitutes an example of a Deleuzean nomadic war machine: that is, a critical character who borrows aspects of the State Apparatus and then twists and shapes them into weapons through which he questions and mocks society for its authoritarian and ideological flaws, and with which he exposes its conceptual and ethical blind spots. In this way, he acts like a mirror, reflecting what is wrong with society, and by implication, with the human ‘nature’ – not only in the fictional world of Gotham, but also in the contemporary era created therein. More specifically, discourse analysis and film analysis will be used here, to engage critically with the Joker’s persona in relation to the changing contexts in which the various films were made, in order to trace the development of the character through a Deleuzoguattarian lens. As will be discussed, Phillips’ Joker (2019) signals the deterritorialization of the Joker from the ambit of Batman’s influence, and opens up the possibility for his further deterritorialization as an increasingly mobile and nomadic catalyst of critical thinking beyond even Gotham itself. Then, thirdly, an in-depth analysis on the five key cinematic Jokers will be completed in terms of the characters’ historical contexts, character backgrounds, and aesthetics. And thereafter, the deterritorializing ‘line of flight’ already underway – as by Phillips’ Joker (2019) – will be continued through the creative media production component of this study, which will entail the conceptualization, design and illustration of three new Joker manifestations, each of which will reflect critically upon failing systems in South African society across select time periods, and how these failing systems have contributed to the collective trauma of marginalized groups of people. The first South African Joker manifestation, set in the 1980s, will reflect upon the faltering political infrastructure during the Apartheid era. The second Joker manifestation, set in the early 2000s, will encapsulate the repercussions of the post-Apartheid neoliberal economic landscape. And the third Joker manifestation, set in the 2010s, will draw attention to sociocultural collapse particularly in the space of gender-based violence and sexual assault. Thus, the creation of these Jokers will act as an exploration of trauma, insofar as the tragedy and pain caused by the above-mentioned failing systems will manifest physically through their character designs. In terms of this, and in keeping with the dynamics of appropriation and inflection that are definitive of nomadic war machines, here focus will fall on how their character aesthetics pose critical questions about relevant issues in the South Africa. On account of this, although this research is by definition situated within the spectacle/performance paradigm, it also runs counter to the largely apolitical orientation of creative media production that occurs therein, through its emphasis, instead, on how such creative media production can also entail critical thought that is aimed at thematizing socio-cultural and politico-economic issues and the trauma that they create; thus, this creative media component aims to encourage a more trauma-aware society through art. , Thesis (MA) -- Faculty of Humanities, School of Language, Media and Communication, 2023
- Full Text:
- Date Issued: 2024-04
Grade 12 literary writing: Perceptions and practices of educators and learners in an English Home Language classroom
- Authors: Krause, Sade
- Date: 2024-04
- Subjects: Creative writing -- Study and teaching , Language and languages -- Study and teaching -- South Africa -- Port Elizabeth , English language -- Study and teaching -- South Africa
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10948/63122 , vital:73188
- Description: This study sought to understand perceptions and practices of the literary writing abilities of educators1 and learners of Grade 12 at a high school in Gqeberha, Eastern Cape. Evidence reveals these abilities to be poor. Interviews with educators in the English Home Language Department at the selected school aimed to gain insight into their approaches to teaching literary writing as well as their comprehension and methods of implementation of the Curriculum Assessment Policy Statement’s guidelines for the teaching of the literary essay. Focus group discussions were held with the predominantly isiXhosa or Afrikaans-speaking learners to gauge whether their identities as isiXhosa and Afrikaans speakers in the English Home Language classroom affect their perceptions of the literary texts they have to read and write about. Lastly, an analysis of the learners’ literary essays provided a window into the translation of writing techniques taught and learned. The study found that literary essay writing and literature study lessons contributed to the alienation learners experienced. Learners’ varying learning styles are not prioritised for literature study and literary essay writing. The educators’ selected approach is partly due to the overloaded curriculum which does not equip teachers with the information and skills to execute lessons which lead to effective acquisition of literary writing skills. The CAPS’s flawed premises of the nature of language and lack of support of educators’ teaching of the literary essay perpetuates the subjugation of learners. A framework is suggested to create access to academic writing skills for the learners. , Thesis (MA) -- Faculty of Humanities, Language, Media and Communication, 2024
- Full Text:
- Date Issued: 2024-04
- Authors: Krause, Sade
- Date: 2024-04
- Subjects: Creative writing -- Study and teaching , Language and languages -- Study and teaching -- South Africa -- Port Elizabeth , English language -- Study and teaching -- South Africa
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10948/63122 , vital:73188
- Description: This study sought to understand perceptions and practices of the literary writing abilities of educators1 and learners of Grade 12 at a high school in Gqeberha, Eastern Cape. Evidence reveals these abilities to be poor. Interviews with educators in the English Home Language Department at the selected school aimed to gain insight into their approaches to teaching literary writing as well as their comprehension and methods of implementation of the Curriculum Assessment Policy Statement’s guidelines for the teaching of the literary essay. Focus group discussions were held with the predominantly isiXhosa or Afrikaans-speaking learners to gauge whether their identities as isiXhosa and Afrikaans speakers in the English Home Language classroom affect their perceptions of the literary texts they have to read and write about. Lastly, an analysis of the learners’ literary essays provided a window into the translation of writing techniques taught and learned. The study found that literary essay writing and literature study lessons contributed to the alienation learners experienced. Learners’ varying learning styles are not prioritised for literature study and literary essay writing. The educators’ selected approach is partly due to the overloaded curriculum which does not equip teachers with the information and skills to execute lessons which lead to effective acquisition of literary writing skills. The CAPS’s flawed premises of the nature of language and lack of support of educators’ teaching of the literary essay perpetuates the subjugation of learners. A framework is suggested to create access to academic writing skills for the learners. , Thesis (MA) -- Faculty of Humanities, Language, Media and Communication, 2024
- Full Text:
- Date Issued: 2024-04
Guidelines for improved coordination of public works projects in Buffalo City Metro
- Authors: Puta, Mabhelonke
- Date: 2024-04
- Subjects: Public works -- South Africa , Infrastructure (Economics) -- South Africa , Economic development projects -- South Africa
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10948/64775 , vital:73890
- Description: This aim of this study was to determine how improved coordination of public works projects in Buffalo City Metro (BCM) can be promoted. The aim was predicated on the notion that coordination failure adversely affects scope, time, budget, and quality. A pragmatic worldview related to problem- solving informed the collection of both textual and statistical data for the study through surveys and interviews. In BCM public works projects failures in coordination have resulted in negative outcomes of project implementation. The study shows a correlation between coordination and project success, whilst failure in coordination will negatively impact project cost and project scope, resulting in project failure. The study was able to determine prioritised coordination activities. The study further developed coordination guidelines that mitigate coordination failure by outlining mechanisms, which are as follows: appointment of a coordination leader, scheduling coordination activities, participate plan and quality assurance plan. The outputs of these are the coordination of meetings, the online coordination of software, a schedule of lessons learnt, the drawing up of an execution plan and establishing performance incentives. , Thesis (MSc) -- Faculty of Engineering, the Built Environment and Technology, School of Built Environment and Civil Engineering, 2024
- Full Text:
- Date Issued: 2024-04
- Authors: Puta, Mabhelonke
- Date: 2024-04
- Subjects: Public works -- South Africa , Infrastructure (Economics) -- South Africa , Economic development projects -- South Africa
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10948/64775 , vital:73890
- Description: This aim of this study was to determine how improved coordination of public works projects in Buffalo City Metro (BCM) can be promoted. The aim was predicated on the notion that coordination failure adversely affects scope, time, budget, and quality. A pragmatic worldview related to problem- solving informed the collection of both textual and statistical data for the study through surveys and interviews. In BCM public works projects failures in coordination have resulted in negative outcomes of project implementation. The study shows a correlation between coordination and project success, whilst failure in coordination will negatively impact project cost and project scope, resulting in project failure. The study was able to determine prioritised coordination activities. The study further developed coordination guidelines that mitigate coordination failure by outlining mechanisms, which are as follows: appointment of a coordination leader, scheduling coordination activities, participate plan and quality assurance plan. The outputs of these are the coordination of meetings, the online coordination of software, a schedule of lessons learnt, the drawing up of an execution plan and establishing performance incentives. , Thesis (MSc) -- Faculty of Engineering, the Built Environment and Technology, School of Built Environment and Civil Engineering, 2024
- Full Text:
- Date Issued: 2024-04
Guidelines towards the use of virtual consultation in primary healthcare
- Ndome Ndame, Evelyne Alexandra
- Authors: Ndome Ndame, Evelyne Alexandra
- Date: 2024-04
- Subjects: Telecommunication in medicine , Medicine -- Communication systems , Health services administration -- Information technology
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10948/64728 , vital:73872
- Description: In an environment of expanding demand on the healthcare system to provide equitable, accessible, and safe healthcare, the use of information and communication technology (ICT) is one of the strategies identified to fulfil such expectations. To make this achievable, ICTs are integrated in healthcare using telehealth, which permits the provision of remote healthcare by using virtual health technologies. One domain of telehealth which permits remote care is virtual consultations. It is an important tool in the healthcare industry used to promote access to healthcare services, especially for elderly people or people with disabilities, those suffering from chronic diseases such as cardiovascular disease, diabetes, and hypertension, among others, and for people in rural and underserved communities. This is possible using videoconferencing technology, telephone consultations, email, or instant messaging. Virtual consultations are becoming an integral part of the healthcare industry all over the world, and it is important to understand how to make use of them to promote healthcare access. The purpose of this study was to create guidelines to assist primary health care professionals in the most effective ways of using virtual consultations to improve access to essential health care services. As such, the objectives governing this study were to identify the role that virtual consultations play in healthcare, to investigate the factors that impact the use of virtual consultations, to review the existing guidelines on virtual consultations, as well as to identify the requirements needed for virtual consultations. This research followed several aspects to guide the methodology of this study. The research process governing this research was the design science research process. The research made use of literature reviews, argumentation, and a survey for data collection as well as a qualitative content analysis to analyse the data. The data collection consisted of 32 survey responses, which aided in the identification of the factors impacting the use of virtual consultations. The results showed that virtual consultations are utilised for various aspects of care delivery, but face-to-face consultations are still the first choice of consultation. , Thesis (MIT) -- Faculty of Engineering, the Built Environment and Technology, School of Information Technology, 2024
- Full Text:
- Date Issued: 2024-04
- Authors: Ndome Ndame, Evelyne Alexandra
- Date: 2024-04
- Subjects: Telecommunication in medicine , Medicine -- Communication systems , Health services administration -- Information technology
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10948/64728 , vital:73872
- Description: In an environment of expanding demand on the healthcare system to provide equitable, accessible, and safe healthcare, the use of information and communication technology (ICT) is one of the strategies identified to fulfil such expectations. To make this achievable, ICTs are integrated in healthcare using telehealth, which permits the provision of remote healthcare by using virtual health technologies. One domain of telehealth which permits remote care is virtual consultations. It is an important tool in the healthcare industry used to promote access to healthcare services, especially for elderly people or people with disabilities, those suffering from chronic diseases such as cardiovascular disease, diabetes, and hypertension, among others, and for people in rural and underserved communities. This is possible using videoconferencing technology, telephone consultations, email, or instant messaging. Virtual consultations are becoming an integral part of the healthcare industry all over the world, and it is important to understand how to make use of them to promote healthcare access. The purpose of this study was to create guidelines to assist primary health care professionals in the most effective ways of using virtual consultations to improve access to essential health care services. As such, the objectives governing this study were to identify the role that virtual consultations play in healthcare, to investigate the factors that impact the use of virtual consultations, to review the existing guidelines on virtual consultations, as well as to identify the requirements needed for virtual consultations. This research followed several aspects to guide the methodology of this study. The research process governing this research was the design science research process. The research made use of literature reviews, argumentation, and a survey for data collection as well as a qualitative content analysis to analyse the data. The data collection consisted of 32 survey responses, which aided in the identification of the factors impacting the use of virtual consultations. The results showed that virtual consultations are utilised for various aspects of care delivery, but face-to-face consultations are still the first choice of consultation. , Thesis (MIT) -- Faculty of Engineering, the Built Environment and Technology, School of Information Technology, 2024
- Full Text:
- Date Issued: 2024-04
Herpetofaunal diversity and affiliations of the Okavango River Basin, with specific focus on the Angolan headwaters
- Authors: Conradie, Werner
- Date: 2024-04
- Subjects: Water conservation -- Okavango River Delta , Watersheds -- Okavango River -- Angola , Biodiversity -- Angola
- Language: English
- Type: Doctorate theses , text
- Identifier: http://hdl.handle.net/10948/63667 , vital:73576
- Description: Although Africa is reputed to possess some of the richest herpetofaunal diversities in the world, a number of areas remain poorly documented and thus inadequately conserved. One such area in particular is the south-eastern part of Angola. Angola endured a long struggle for independence with a protracted civil war that lasted for nearly three decades, leaving the status of the country’s biodiversity in turmoil. Over the past two decades, Angola has become more accessible for biodiversity surveys, opening up new opportunities to document these previously poorly studied areas and help conserve its biodiversity. South-eastern Angola is the water source of the world-renowned Okavango Delta. However very little is known about the biodiversity, diversity status and conservation significance of the headwaters supplying the largest inland delta in the world. To address this bias in sampling and to investigate the conservation importance of the region, a series of rapid biodiversity surveys of the Angolan Okavango River Basin were conducted between 2012 and 2019. This study contributed over 2150 individual records of amphibians and reptiles, representing 88 reptile and 43 amphibian species. At least 15 species were added to the growing country checklist, with the south-eastern region of Angola now comprising 113 reptile species and 51 amphibian species. Because of this study, the area is now one of the most species-rich and well-studied areas in Angola. This study provided the first genetic data for 26 species, and sequences containing Angolan specimens for the first time were generated for 80 species, of which 23 species have originally been described from Angola. Maximum likelihood and Bayesian inference analyses, supported by species delimitation analyses, were utilised to validate specific species statuses. This allowed for the description of five new species of snake, one gecko and two frogs for Angola. The material further contributed to the description of a new genus of snakes. Numerous undescribed and potentially cryptic species were identified, long-lasting taxonomic issues were resolved, and various taxonomic adjustments were emphasised. Further contributions of the material include assisting in the revision of targeted Angolan amphibian and reptile groups as well as large-scale phylogenetic studies across Africa. , Thesis (PhD) -- Faculty of Science, School of Natural Resource Science & Management, 2024
- Full Text:
- Date Issued: 2024-04
- Authors: Conradie, Werner
- Date: 2024-04
- Subjects: Water conservation -- Okavango River Delta , Watersheds -- Okavango River -- Angola , Biodiversity -- Angola
- Language: English
- Type: Doctorate theses , text
- Identifier: http://hdl.handle.net/10948/63667 , vital:73576
- Description: Although Africa is reputed to possess some of the richest herpetofaunal diversities in the world, a number of areas remain poorly documented and thus inadequately conserved. One such area in particular is the south-eastern part of Angola. Angola endured a long struggle for independence with a protracted civil war that lasted for nearly three decades, leaving the status of the country’s biodiversity in turmoil. Over the past two decades, Angola has become more accessible for biodiversity surveys, opening up new opportunities to document these previously poorly studied areas and help conserve its biodiversity. South-eastern Angola is the water source of the world-renowned Okavango Delta. However very little is known about the biodiversity, diversity status and conservation significance of the headwaters supplying the largest inland delta in the world. To address this bias in sampling and to investigate the conservation importance of the region, a series of rapid biodiversity surveys of the Angolan Okavango River Basin were conducted between 2012 and 2019. This study contributed over 2150 individual records of amphibians and reptiles, representing 88 reptile and 43 amphibian species. At least 15 species were added to the growing country checklist, with the south-eastern region of Angola now comprising 113 reptile species and 51 amphibian species. Because of this study, the area is now one of the most species-rich and well-studied areas in Angola. This study provided the first genetic data for 26 species, and sequences containing Angolan specimens for the first time were generated for 80 species, of which 23 species have originally been described from Angola. Maximum likelihood and Bayesian inference analyses, supported by species delimitation analyses, were utilised to validate specific species statuses. This allowed for the description of five new species of snake, one gecko and two frogs for Angola. The material further contributed to the description of a new genus of snakes. Numerous undescribed and potentially cryptic species were identified, long-lasting taxonomic issues were resolved, and various taxonomic adjustments were emphasised. Further contributions of the material include assisting in the revision of targeted Angolan amphibian and reptile groups as well as large-scale phylogenetic studies across Africa. , Thesis (PhD) -- Faculty of Science, School of Natural Resource Science & Management, 2024
- Full Text:
- Date Issued: 2024-04
IL-4/ IL-13 directed microglial activation and differentiation in response to LPS-induced neuroinflammation
- Authors: Ackerdien, Shiraz
- Date: 2024-04
- Subjects: Inflammation , Inflammation -- Treatment , Anti-inflammatory agents
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10948/63606 , vital:73554
- Description: Microglia activation is a common hallmark of neuroinflammation that occurs during pathogen invasion or lipopolysaccharide (LPS)-induced inflammation. A neuroinflammatory response is elicited by the release of proinflammatory cytokines which stimulates microglia in an autocrine manner to be polarized into classically activated, pro-inflammatory M1 cells. Prolonged exposure to the inflammatory response can have disastrous effects on the central nervous system (CNS). However, microglia can alternatively be polarized into the activated M2 anti-inflammatory phenotype, but the exact molecular mechanism mediating this phenotypic switch remains poorly understood. Studies have shown that interleukin (IL)-4 can induce the M2 phenotype and activate the signal transducer and activator of the transcription 6 (STAT6) signalling pathway that in turn provokes a beneficial Th2 immune response. Since IL-4 and IL-13 share a common IL-4 receptor alpha (IL-4Rα) chain, it is possible that alternative microglia differentiation and its anti-inflammatory action also involve IL-13. This study aimed to investigate how IL-13 and STAT6 signalling orchestrates the microglial response and differentiation associated with LPS-induced inflammation. Furthermore, the molecular mechanisms that relieve LPS-induced neuroinflammation and neural protection through IL-13-enhanced BDNF signalling were also investigated. C8-B4 microglial cells were induced with LPS to exhibit an M1 pro-inflammatory phenotype or stimulated with IL-4 and/or IL-13 to exhibit an M2 anti-inflammatory microglial phenotype. The cell viability following LPS, IL-4, and/ or IL-13 exposure was determined. The LPS-induced neuroinflammatory response and the anti-inflammatory response induced by IL-4 and IL-13 which promotes STAT-6 signalling were determined by measuring TNFα, IL-1β, and BDNF protein concentrations using ELISA assays. The polarising effects of LPS and IL-4/IL-13 cytokines were also examined via changes in the expression of Iba-1, CD206, CD86, and STAT-6 determined by immunofluorescence analysis. These changes were further investigated by quantifying the mRNA transcripts of TNFα, IL-1 β, Arg-1, CD206, IL-4R, and STAT-6 and BDNF using qRT-PCR. , Thesis (MSc) -- Faculty of Science, School of Biomolecular & Chemical Sciences, 2024
- Full Text:
- Date Issued: 2024-04
- Authors: Ackerdien, Shiraz
- Date: 2024-04
- Subjects: Inflammation , Inflammation -- Treatment , Anti-inflammatory agents
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10948/63606 , vital:73554
- Description: Microglia activation is a common hallmark of neuroinflammation that occurs during pathogen invasion or lipopolysaccharide (LPS)-induced inflammation. A neuroinflammatory response is elicited by the release of proinflammatory cytokines which stimulates microglia in an autocrine manner to be polarized into classically activated, pro-inflammatory M1 cells. Prolonged exposure to the inflammatory response can have disastrous effects on the central nervous system (CNS). However, microglia can alternatively be polarized into the activated M2 anti-inflammatory phenotype, but the exact molecular mechanism mediating this phenotypic switch remains poorly understood. Studies have shown that interleukin (IL)-4 can induce the M2 phenotype and activate the signal transducer and activator of the transcription 6 (STAT6) signalling pathway that in turn provokes a beneficial Th2 immune response. Since IL-4 and IL-13 share a common IL-4 receptor alpha (IL-4Rα) chain, it is possible that alternative microglia differentiation and its anti-inflammatory action also involve IL-13. This study aimed to investigate how IL-13 and STAT6 signalling orchestrates the microglial response and differentiation associated with LPS-induced inflammation. Furthermore, the molecular mechanisms that relieve LPS-induced neuroinflammation and neural protection through IL-13-enhanced BDNF signalling were also investigated. C8-B4 microglial cells were induced with LPS to exhibit an M1 pro-inflammatory phenotype or stimulated with IL-4 and/or IL-13 to exhibit an M2 anti-inflammatory microglial phenotype. The cell viability following LPS, IL-4, and/ or IL-13 exposure was determined. The LPS-induced neuroinflammatory response and the anti-inflammatory response induced by IL-4 and IL-13 which promotes STAT-6 signalling were determined by measuring TNFα, IL-1β, and BDNF protein concentrations using ELISA assays. The polarising effects of LPS and IL-4/IL-13 cytokines were also examined via changes in the expression of Iba-1, CD206, CD86, and STAT-6 determined by immunofluorescence analysis. These changes were further investigated by quantifying the mRNA transcripts of TNFα, IL-1 β, Arg-1, CD206, IL-4R, and STAT-6 and BDNF using qRT-PCR. , Thesis (MSc) -- Faculty of Science, School of Biomolecular & Chemical Sciences, 2024
- Full Text:
- Date Issued: 2024-04
Implementation of the world health organization surgical safety checklist in the operating room in a private hospital in the Nelson Mandela Bay Municipality
- Authors: Obeng, Emelia
- Date: 2024-04
- Subjects: World Health Organization , Operating room nursing , Preoperative care
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10948/63517 , vital:73384
- Description: The World Health Organisation Surgical Safety Checklist (WHO SSC) was developed to improve teamwork among healthcare professionals and ensure consistent use of safety processes in the operating room (Abbott et al., 2018: 147). The WHO SSC has successfully reduced common and avoidable surgical errors relating to nerve cutting, among others (Jain et al., 2018:7). However, the implementation of the WHO SSC has not been widely acknowledged in South Africa due to specific barriers (Koopman, 2018: 20; Sauls, 2019: 15). To this end, the aim of this study was two-fold: (i) to determine the factors that contribute to the implementation of the WHO SSC among operating room healthcare professionals and (ii) to develop a contextually appropriate process implementation guide that may be used to facilitate utilisation of the WHO SSC in a private operating room healthcare facility. A non-experimental descriptive quantitative approach underpinned by positivism and a descriptive exploratory survey was used to study the factors contributing to implementing the WHO SSC. A self-reported questionnaire was used as the method for data collection. Purposive sampling was adopted by selecting all the 130 operating room staff directly involved in completing the WHO SSC. All 130 respondents completed and returned the questionnaire. Data were analysed using the Statistical Package Software for the Social Sciences (SPSS) Version 28.0 for Windows (IBM Corp, 2021). The study described four factors (i.e. awareness, relative advantage, complexity, and usability) contributing to the implementation of the WHO SSC. The analysis revealed a significant inter-relationship between two factors (i.e. relative advantage and awareness) and characteristics of the operating room healthcare professionals (regarding highest qualification, current age and work experience). The study’s main contribution to the existing body of knowledge is the proposed process-oriented implementation guide, including a readiness assessment template for effective implementation of the WHO SSC. It is recommended that good knowledge of the WHO SSC should be created by making operating room healthcare professionals aware of the arrangements and interventions by the private hospital to implement the WHO SSC. , Thesis (MCur) -- Faculty of Health Sciences, School of Clinical care & medicinal sciences , 2024
- Full Text:
- Date Issued: 2024-04
- Authors: Obeng, Emelia
- Date: 2024-04
- Subjects: World Health Organization , Operating room nursing , Preoperative care
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10948/63517 , vital:73384
- Description: The World Health Organisation Surgical Safety Checklist (WHO SSC) was developed to improve teamwork among healthcare professionals and ensure consistent use of safety processes in the operating room (Abbott et al., 2018: 147). The WHO SSC has successfully reduced common and avoidable surgical errors relating to nerve cutting, among others (Jain et al., 2018:7). However, the implementation of the WHO SSC has not been widely acknowledged in South Africa due to specific barriers (Koopman, 2018: 20; Sauls, 2019: 15). To this end, the aim of this study was two-fold: (i) to determine the factors that contribute to the implementation of the WHO SSC among operating room healthcare professionals and (ii) to develop a contextually appropriate process implementation guide that may be used to facilitate utilisation of the WHO SSC in a private operating room healthcare facility. A non-experimental descriptive quantitative approach underpinned by positivism and a descriptive exploratory survey was used to study the factors contributing to implementing the WHO SSC. A self-reported questionnaire was used as the method for data collection. Purposive sampling was adopted by selecting all the 130 operating room staff directly involved in completing the WHO SSC. All 130 respondents completed and returned the questionnaire. Data were analysed using the Statistical Package Software for the Social Sciences (SPSS) Version 28.0 for Windows (IBM Corp, 2021). The study described four factors (i.e. awareness, relative advantage, complexity, and usability) contributing to the implementation of the WHO SSC. The analysis revealed a significant inter-relationship between two factors (i.e. relative advantage and awareness) and characteristics of the operating room healthcare professionals (regarding highest qualification, current age and work experience). The study’s main contribution to the existing body of knowledge is the proposed process-oriented implementation guide, including a readiness assessment template for effective implementation of the WHO SSC. It is recommended that good knowledge of the WHO SSC should be created by making operating room healthcare professionals aware of the arrangements and interventions by the private hospital to implement the WHO SSC. , Thesis (MCur) -- Faculty of Health Sciences, School of Clinical care & medicinal sciences , 2024
- Full Text:
- Date Issued: 2024-04
Incorporating emotion detection in text-dependent speaker authentication
- van Rensburg, Ebenhaeser Otto Janse, Von Solms, Rossouw
- Authors: van Rensburg, Ebenhaeser Otto Janse , Von Solms, Rossouw
- Date: 2024-04
- Subjects: Automatic speech recognition , Biometric identification , Computer networks -- Security measures , Computer networks -- Access control
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10948/64566 , vital:73767
- Description: Biometric authentication allows a person to access sensitive information using unique physical characteristics. Voice, as a biometric authentication method, is gaining popularity due to its unique characteristics and widespread availability on smartphones and other devices. It offers a secure and user-friendly alternative to traditional password-based authentication and allows a less intrusive authentication method than fingerprint authentication. Furthermore, a vast amount of information is portrayed through voice, such as age, gender, health, and emotional state. Gaining illegitimate access to information becomes significantly more difficult as biometrics are difficult to steal, and countermeasures to techniques such as replay attacks are constantly being improved. However, illegitimate access can be gained by forcing a legitimate person to authenticate themselves through voice. This study investigates how the emotion(s) carried by voice can assist in detecting if authentication was performed under duress. Knowledge is contributed using a three-phased approach: information gathering, experimentation, and deliberation. The experimentation phase is further divided into three phases to extract data, implement findings, and assess the value of determining duress using voice. This phased approach to experimentation ensures minimal change in variables and allows the drawn conclusions to be relevant to each phase. The first phase examines datasets and classifiers; the second phase explores feature enhancement techniques and their impact; and the third phase discusses performance measurements and their value to emotion detection. , Thesis (DPhil) -- Faculty Of Engineering, the Built Environment and Technology, School of Information Technology, 2024
- Full Text:
- Date Issued: 2024-04
- Authors: van Rensburg, Ebenhaeser Otto Janse , Von Solms, Rossouw
- Date: 2024-04
- Subjects: Automatic speech recognition , Biometric identification , Computer networks -- Security measures , Computer networks -- Access control
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10948/64566 , vital:73767
- Description: Biometric authentication allows a person to access sensitive information using unique physical characteristics. Voice, as a biometric authentication method, is gaining popularity due to its unique characteristics and widespread availability on smartphones and other devices. It offers a secure and user-friendly alternative to traditional password-based authentication and allows a less intrusive authentication method than fingerprint authentication. Furthermore, a vast amount of information is portrayed through voice, such as age, gender, health, and emotional state. Gaining illegitimate access to information becomes significantly more difficult as biometrics are difficult to steal, and countermeasures to techniques such as replay attacks are constantly being improved. However, illegitimate access can be gained by forcing a legitimate person to authenticate themselves through voice. This study investigates how the emotion(s) carried by voice can assist in detecting if authentication was performed under duress. Knowledge is contributed using a three-phased approach: information gathering, experimentation, and deliberation. The experimentation phase is further divided into three phases to extract data, implement findings, and assess the value of determining duress using voice. This phased approach to experimentation ensures minimal change in variables and allows the drawn conclusions to be relevant to each phase. The first phase examines datasets and classifiers; the second phase explores feature enhancement techniques and their impact; and the third phase discusses performance measurements and their value to emotion detection. , Thesis (DPhil) -- Faculty Of Engineering, the Built Environment and Technology, School of Information Technology, 2024
- Full Text:
- Date Issued: 2024-04
Investigating the anti-inflammatory effect of blueberry-AuNP on microglial cells and obese rat brains
- Authors: Ngwato, Anacia
- Date: 2024-04
- Subjects: Anti-inflammatory agents , Brain -- Anatomy , Brain -- Physiology
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10948/64266 , vital:73670
- Description: Nanotoxicology is a field of study that investigates how nanomaterials interact with biological systems. It focuses on understanding the correlation between the physicochemical properties of nanomaterials, such as size and stability, and their potential toxic effects. Gold nanoparticles (AuNPs), for instance, have a variety of applications in the biological sciences. Therefore, there is a great deal of attention given to evaluating their toxicity to ensure their safe and effective use in biological systems. Anti-inflammatory AuNPs have shown to be a desirable application in obesity treatments since obesity is associated with systematic inflammation. Thus, the study aimed to evaluate the anti-inflammatory effect of BE-AuNPs on C8-B4 microglial cell lines and, to validate the results, the grey matter of brain tissue of obese rats treated with BE-AuNPs. Following the synthesis and characterization of BE-AuNPs, C8-B4 microglial cells were treated with the BE-AuNPs and were evaluated through MTT, HRTEM imaging, qPCR, and ROS. LPS was used to activate the cells. Concentration-dependent toxicity of BE-AuNPs and cellular uptake was observed. The qPCR results showed that the BE-AuNPs decreased the LPS-induced inflammation in the cells. The BE-AuNPs were shown to reduce ROS in inflammatory conditions in the cells. Rat brain tissue analysis through qPCR and ROS demonstrated that BE-AuNPs reduce HFD-induced inflammation and had no ROS effects on the brain, respectively. Thus, leading to a conclusion the BE-AuNPs used in this study are anti-inflammatory. , Thesis (MSc) -- Faculty of Science, Biomolecular & Chemical Sciences, 2024
- Full Text:
- Date Issued: 2024-04
- Authors: Ngwato, Anacia
- Date: 2024-04
- Subjects: Anti-inflammatory agents , Brain -- Anatomy , Brain -- Physiology
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10948/64266 , vital:73670
- Description: Nanotoxicology is a field of study that investigates how nanomaterials interact with biological systems. It focuses on understanding the correlation between the physicochemical properties of nanomaterials, such as size and stability, and their potential toxic effects. Gold nanoparticles (AuNPs), for instance, have a variety of applications in the biological sciences. Therefore, there is a great deal of attention given to evaluating their toxicity to ensure their safe and effective use in biological systems. Anti-inflammatory AuNPs have shown to be a desirable application in obesity treatments since obesity is associated with systematic inflammation. Thus, the study aimed to evaluate the anti-inflammatory effect of BE-AuNPs on C8-B4 microglial cell lines and, to validate the results, the grey matter of brain tissue of obese rats treated with BE-AuNPs. Following the synthesis and characterization of BE-AuNPs, C8-B4 microglial cells were treated with the BE-AuNPs and were evaluated through MTT, HRTEM imaging, qPCR, and ROS. LPS was used to activate the cells. Concentration-dependent toxicity of BE-AuNPs and cellular uptake was observed. The qPCR results showed that the BE-AuNPs decreased the LPS-induced inflammation in the cells. The BE-AuNPs were shown to reduce ROS in inflammatory conditions in the cells. Rat brain tissue analysis through qPCR and ROS demonstrated that BE-AuNPs reduce HFD-induced inflammation and had no ROS effects on the brain, respectively. Thus, leading to a conclusion the BE-AuNPs used in this study are anti-inflammatory. , Thesis (MSc) -- Faculty of Science, Biomolecular & Chemical Sciences, 2024
- Full Text:
- Date Issued: 2024-04
Investigating ways to limit wasteful expenditure due to punitive property taxes on Gauteng hospitals
- Authors: Molotsi, Obed Lucas
- Date: 2024-04
- Subjects: Real property tax -- South Africa -- Gauteng , Real property -- Valuation -- South Africa -- Gauteng , Finance, Public -- Law and legislation -- South Africa -- Gauteng , Financial management
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10948/64705 , vital:73863
- Description: The PFMA defines fruitless and wasteful expenditure as an expenditure made in vain, and it states that had reasonable care been exercised, such expenditure would and should have been avoided. Among the various forms of wasteful expenditure, the AGSA (AG, 2021) report lists the payment of penalties, or of interest accruing because of late or non-payments, and debt incurred. These expenditures are prevalent in social cluster infrastructure projects, and the waste is attributed to poor planning, weak internal control measures, and lack of oversight on contracts. The Local Municipal Property Act 6 of 2004 (SA Government, 2004) empowers municipalities to develop a land administration process to enforce compliance with land use management schemes, which often is referred to as the steps to be taken to avoid the illegal use of land. The illegal use of land arises when a property owner fails to comply with the provisions of the land scheme, and when the land owner fails to comply with the requirements set out in notices issued in terms of the land use scheme. Illegal land uses arise when property exchanges hands between government departments (vesting), resulting in a change of use. This then leads to a failure by the property owner to update the conditions and property information that should have been in line with the changes enacted in the land use schemes in the asset register. The objective of this research was to investigate ways and the process the Provincial Government of Gauteng should put in place to limit wasteful expenditure and the payment of administrative penalties, or mounting property taxes based on the punitive tariff as the result of engaging in illegal land use. Such illegal land use occurred because the new property owner failed to update the property information and conditions. Based on the data collected through semi-structured interviews, questionnaires administered to a sample completed by the study’s participants, and the secondary research process that included the review of official policy documents, qualitative, and quantitative analysis were performed to achieve important findings of this study. Zoning applies to land with cadastral boundaries, implying that zoning is only applicable to surveyed land. Zones are depicted on the zone scheme maps, and these have the aim to inform land owners of potential development rights that are stipulated in the land use management schemes. Zoning forms the basis for property valuations and property tax (rates) calculation purposes. The other factor used in the calculation of the rate is the value of the rateable properties registered in the valuation roll. Every five years, a new valuation roll is published for review before the adoption by the various municipalities’ councils. The setting of tariffs is informed by the budget requirements of the municipalities to enable them to finance or deliver municipal services. The tariff scales are determined in line with the land use categories. Municipalities publish the tariffs yearly, after the adoption of the budget by the municipalities’ councils. The remedies available to municipalities is levying a punitive rate to try to change the owner’s land use and move it from unauthorised/illegal use of the land outside the category of use to an updated, legal use. The research findings indicate that the Gauteng Provincial Government’s relevant department lacks the necessary structures and processes to monitor changes in the bylaws or land use schemes of municipalities, and the payment of property rates does not hold any strategic importance in the management of properties. The department did not have a system or process in place to review the valuation roll, or to monitor the annual tariff rate adjustments. Therefore, the present research recommends several measures the department will have to implement to limit wasteful and fruitless expenditure regarding property rate payments. , Thesis (MSc) -- Faculty of Engineering, the Built Environment and Technology, School of Built Environment and Civil Engineering, 2024
- Full Text:
- Date Issued: 2024-04
Investigating ways to limit wasteful expenditure due to punitive property taxes on Gauteng hospitals
- Authors: Molotsi, Obed Lucas
- Date: 2024-04
- Subjects: Real property tax -- South Africa -- Gauteng , Real property -- Valuation -- South Africa -- Gauteng , Finance, Public -- Law and legislation -- South Africa -- Gauteng , Financial management
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10948/64705 , vital:73863
- Description: The PFMA defines fruitless and wasteful expenditure as an expenditure made in vain, and it states that had reasonable care been exercised, such expenditure would and should have been avoided. Among the various forms of wasteful expenditure, the AGSA (AG, 2021) report lists the payment of penalties, or of interest accruing because of late or non-payments, and debt incurred. These expenditures are prevalent in social cluster infrastructure projects, and the waste is attributed to poor planning, weak internal control measures, and lack of oversight on contracts. The Local Municipal Property Act 6 of 2004 (SA Government, 2004) empowers municipalities to develop a land administration process to enforce compliance with land use management schemes, which often is referred to as the steps to be taken to avoid the illegal use of land. The illegal use of land arises when a property owner fails to comply with the provisions of the land scheme, and when the land owner fails to comply with the requirements set out in notices issued in terms of the land use scheme. Illegal land uses arise when property exchanges hands between government departments (vesting), resulting in a change of use. This then leads to a failure by the property owner to update the conditions and property information that should have been in line with the changes enacted in the land use schemes in the asset register. The objective of this research was to investigate ways and the process the Provincial Government of Gauteng should put in place to limit wasteful expenditure and the payment of administrative penalties, or mounting property taxes based on the punitive tariff as the result of engaging in illegal land use. Such illegal land use occurred because the new property owner failed to update the property information and conditions. Based on the data collected through semi-structured interviews, questionnaires administered to a sample completed by the study’s participants, and the secondary research process that included the review of official policy documents, qualitative, and quantitative analysis were performed to achieve important findings of this study. Zoning applies to land with cadastral boundaries, implying that zoning is only applicable to surveyed land. Zones are depicted on the zone scheme maps, and these have the aim to inform land owners of potential development rights that are stipulated in the land use management schemes. Zoning forms the basis for property valuations and property tax (rates) calculation purposes. The other factor used in the calculation of the rate is the value of the rateable properties registered in the valuation roll. Every five years, a new valuation roll is published for review before the adoption by the various municipalities’ councils. The setting of tariffs is informed by the budget requirements of the municipalities to enable them to finance or deliver municipal services. The tariff scales are determined in line with the land use categories. Municipalities publish the tariffs yearly, after the adoption of the budget by the municipalities’ councils. The remedies available to municipalities is levying a punitive rate to try to change the owner’s land use and move it from unauthorised/illegal use of the land outside the category of use to an updated, legal use. The research findings indicate that the Gauteng Provincial Government’s relevant department lacks the necessary structures and processes to monitor changes in the bylaws or land use schemes of municipalities, and the payment of property rates does not hold any strategic importance in the management of properties. The department did not have a system or process in place to review the valuation roll, or to monitor the annual tariff rate adjustments. Therefore, the present research recommends several measures the department will have to implement to limit wasteful and fruitless expenditure regarding property rate payments. , Thesis (MSc) -- Faculty of Engineering, the Built Environment and Technology, School of Built Environment and Civil Engineering, 2024
- Full Text:
- Date Issued: 2024-04
Investigation of four roof-shaped host compounds for their separation potential of mixtures of guest Isomers and related compounds
- Authors: Senekal, Ulrich
- Date: 2024-04
- Subjects: Grignard reagents , Optical isomers -- Analysis , Supramolecular chemistry
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10948/64368 , vital:73684
- Description: The inclusion ability of four roof-shaped host compounds, namely trans-9,10-dihydro-9,10- ethanoanthracene-11,12-dicarboxylic acid (H1), dimethyl trans-9,10-dihydro-9,10- ethanoanthracene-11,12-dicarboxylate (H2), trans-α,α,α’,α’-tetraphenyl-9,10-dihydro-9,10- ethanoanthracene-11,12-dimethanol (H3) and trans-α,α,α’,α’-tetrakis(4-chlorophenyl)-9,10- dihydro-9,10-ethanoanthracene-11,12-dimethanol (H4), were investigated when presented with numerous guest series (eight in number), including the xylene isomers and ethylbenzene, pyridine and the methylpyridine isomers, structurally related toluene, ethylbenzene and cumene, the dichlorobenzenes, six-membered heterocyclic ring compounds (dioxane, morpholine, piperidine and pyridine), anisole and the methylanisole isomers, anisole and the bromoanisole guests, and phenol and the methoxyphenol isomers. The four host compounds were synthesized via Diels-Alder (H1), esterification (H2) and Grignard addition (H3 and H4) reactions, producing yields of product of up to 93%. The yields for the Grignard reactions were lower, 54 and 37%, for the corresponding procedures using phenylmagnesium bromide or 4-chlorophenylmagnesium bromide. Computational molecular modelling studies were conducted on all four host compounds, and the resultant molecular geometries compared with the apohost (guest-free) crystal structures, when available. The geometries of the lowest energy conformers were in close correlation with the observed host structures as obtained from the apohost crystal structures (unfortunately, H3 and H4 were not able to form adequate quality crystals for SCXRD analyses). Interestingly, H1–H4 displayed intramolecular non-classical C–H∙∙∙O hydrogen bonds, while only H1 and H2 demonstrated intermolecular interactions of this type. H3 and H4 assumed one of two forms depending on the guest that was employed: the “active” form presented a strong intramolecular O–H∙∙∙O hydrogen bond, while the “inactive” form possessed weak π∙∙∙π and O–H∙∙∙π interactions. All of the host compounds were subjected to crystallization experiments from each of the guest species, as well as from mixtures of guests from each series (the guest competition experiments), where 1H-, 13C-NMR spectroscopy, GC-MS and/or GC-FID were used to analyse any resultant solids formed, as applicable. Single crystal X-ray diffraction (SCXRD) experiments were carried out on each single solvent complex produced in this work, where the crystal quality was suitable, while thermal analyses were also employed on these to determine their relative thermal stabilities. During the single-guest crystallization experiments, H4 was found to be remarkable in its inclusion ability, forming complexes with all but p-dichlorobenzene, typically with a 1:1 host:guest (H:G) ratio. H1 was more selective in its inclusion behaviour, not enclathrating cumene, 3-bromoanisole, phenol or the three methoxyphenol isomers (favouring 1:1 or 2:1 H:G ratios where complexation was successful). Interestingly, H1 formed salts when presented with 2- and 3-methylpyridine, and morpholine and piperidine. H2 and H3 were less remarkable in their inclusion ability, furnishing apohost crystals or gels in some experiments (typically a 3:1 H:G ratio was favoured for both when complexation occurred). Of the four roof-shaped host compounds, H1 and H4 displayed enhanced selectivities for certain guest species, showing near-complete affinity for a specific guest compound when presented with a guest mixture. H1 was able to include 100.0 and 98.8% p-dichlorobenzene (p-DCB) (from m-DCB/p-DCB and o-DCB/p-DCB mixtures), 96.6 and 93.6% p-xylene (p-Xy) (from m-Xy/p-Xy and o-Xy/p-Xy), 99.3% 4-methylanisole (4-MA) (from 2-MA/4-MA) and 97.1% 4-bromoanisole (4-BA) (from ANI/2-BA/3-BA/4-BA, where ANI is anisole). Host compound H4 was able to include ≈ 90% of selected meta-substituted guests, while H2 and H3 demonstrated moderate preferences for the guest compounds employed in this work (< 60%). It was concluded that some xylene guest mixtures may be purified using all but H2, whereas only H1 and H2 showed potential in separating the pyridines. All but H2 may also be employed in the separation of selected dichlorobenzene mixtures, while H2 showed potential for the separation of the six-membered heterocyclic guest compounds (dioxane, morpholine, piperidine and pyridine), were these ever required to be separated. Both H1 and H4 exhibited an overwhelming affinity for the methyl- and bromoanisole guest compounds, and this work has shown that these are likely host candidates for the purification of a variety of these guest mixtures through supramolecular strategies. SCXRD analyses showed that H1 experienced intermolecular host···host hydrogen bonding interactions between the carboxylic acid functional groups, while H2 typically demonstrated intermolecular non-classical hydrogen bonds in its complexes, forming sheets of host molecules along the c-axis. H4 preferred the “inactive” form whereas H3 assumed either an “active” or “inactive“ form. Various host···guest interactions such as π∙∙∙π, C–H∙∙∙π, C–O∙∙∙π, hydrogen bonding and other short contacts were responsible for guest retention in the crystal structures. Thermal analyses were conducted on all of the successfully formed complexes. Ton (the guest release onset temperature) and Tp (the temperature at which the guest release was most rapid) were recorded, when possible, while the mass losses associated with the guest release event were compared with those mass losses expected, in most cases. , Thesis (PhD) -- Faculty of Science, School of Biomolecular & Chemical Sciences, 2024
- Full Text:
- Date Issued: 2024-04
- Authors: Senekal, Ulrich
- Date: 2024-04
- Subjects: Grignard reagents , Optical isomers -- Analysis , Supramolecular chemistry
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10948/64368 , vital:73684
- Description: The inclusion ability of four roof-shaped host compounds, namely trans-9,10-dihydro-9,10- ethanoanthracene-11,12-dicarboxylic acid (H1), dimethyl trans-9,10-dihydro-9,10- ethanoanthracene-11,12-dicarboxylate (H2), trans-α,α,α’,α’-tetraphenyl-9,10-dihydro-9,10- ethanoanthracene-11,12-dimethanol (H3) and trans-α,α,α’,α’-tetrakis(4-chlorophenyl)-9,10- dihydro-9,10-ethanoanthracene-11,12-dimethanol (H4), were investigated when presented with numerous guest series (eight in number), including the xylene isomers and ethylbenzene, pyridine and the methylpyridine isomers, structurally related toluene, ethylbenzene and cumene, the dichlorobenzenes, six-membered heterocyclic ring compounds (dioxane, morpholine, piperidine and pyridine), anisole and the methylanisole isomers, anisole and the bromoanisole guests, and phenol and the methoxyphenol isomers. The four host compounds were synthesized via Diels-Alder (H1), esterification (H2) and Grignard addition (H3 and H4) reactions, producing yields of product of up to 93%. The yields for the Grignard reactions were lower, 54 and 37%, for the corresponding procedures using phenylmagnesium bromide or 4-chlorophenylmagnesium bromide. Computational molecular modelling studies were conducted on all four host compounds, and the resultant molecular geometries compared with the apohost (guest-free) crystal structures, when available. The geometries of the lowest energy conformers were in close correlation with the observed host structures as obtained from the apohost crystal structures (unfortunately, H3 and H4 were not able to form adequate quality crystals for SCXRD analyses). Interestingly, H1–H4 displayed intramolecular non-classical C–H∙∙∙O hydrogen bonds, while only H1 and H2 demonstrated intermolecular interactions of this type. H3 and H4 assumed one of two forms depending on the guest that was employed: the “active” form presented a strong intramolecular O–H∙∙∙O hydrogen bond, while the “inactive” form possessed weak π∙∙∙π and O–H∙∙∙π interactions. All of the host compounds were subjected to crystallization experiments from each of the guest species, as well as from mixtures of guests from each series (the guest competition experiments), where 1H-, 13C-NMR spectroscopy, GC-MS and/or GC-FID were used to analyse any resultant solids formed, as applicable. Single crystal X-ray diffraction (SCXRD) experiments were carried out on each single solvent complex produced in this work, where the crystal quality was suitable, while thermal analyses were also employed on these to determine their relative thermal stabilities. During the single-guest crystallization experiments, H4 was found to be remarkable in its inclusion ability, forming complexes with all but p-dichlorobenzene, typically with a 1:1 host:guest (H:G) ratio. H1 was more selective in its inclusion behaviour, not enclathrating cumene, 3-bromoanisole, phenol or the three methoxyphenol isomers (favouring 1:1 or 2:1 H:G ratios where complexation was successful). Interestingly, H1 formed salts when presented with 2- and 3-methylpyridine, and morpholine and piperidine. H2 and H3 were less remarkable in their inclusion ability, furnishing apohost crystals or gels in some experiments (typically a 3:1 H:G ratio was favoured for both when complexation occurred). Of the four roof-shaped host compounds, H1 and H4 displayed enhanced selectivities for certain guest species, showing near-complete affinity for a specific guest compound when presented with a guest mixture. H1 was able to include 100.0 and 98.8% p-dichlorobenzene (p-DCB) (from m-DCB/p-DCB and o-DCB/p-DCB mixtures), 96.6 and 93.6% p-xylene (p-Xy) (from m-Xy/p-Xy and o-Xy/p-Xy), 99.3% 4-methylanisole (4-MA) (from 2-MA/4-MA) and 97.1% 4-bromoanisole (4-BA) (from ANI/2-BA/3-BA/4-BA, where ANI is anisole). Host compound H4 was able to include ≈ 90% of selected meta-substituted guests, while H2 and H3 demonstrated moderate preferences for the guest compounds employed in this work (< 60%). It was concluded that some xylene guest mixtures may be purified using all but H2, whereas only H1 and H2 showed potential in separating the pyridines. All but H2 may also be employed in the separation of selected dichlorobenzene mixtures, while H2 showed potential for the separation of the six-membered heterocyclic guest compounds (dioxane, morpholine, piperidine and pyridine), were these ever required to be separated. Both H1 and H4 exhibited an overwhelming affinity for the methyl- and bromoanisole guest compounds, and this work has shown that these are likely host candidates for the purification of a variety of these guest mixtures through supramolecular strategies. SCXRD analyses showed that H1 experienced intermolecular host···host hydrogen bonding interactions between the carboxylic acid functional groups, while H2 typically demonstrated intermolecular non-classical hydrogen bonds in its complexes, forming sheets of host molecules along the c-axis. H4 preferred the “inactive” form whereas H3 assumed either an “active” or “inactive“ form. Various host···guest interactions such as π∙∙∙π, C–H∙∙∙π, C–O∙∙∙π, hydrogen bonding and other short contacts were responsible for guest retention in the crystal structures. Thermal analyses were conducted on all of the successfully formed complexes. Ton (the guest release onset temperature) and Tp (the temperature at which the guest release was most rapid) were recorded, when possible, while the mass losses associated with the guest release event were compared with those mass losses expected, in most cases. , Thesis (PhD) -- Faculty of Science, School of Biomolecular & Chemical Sciences, 2024
- Full Text:
- Date Issued: 2024-04
Investigation of the host potential of compounds derived from tartaric acid, succinic acid and 1,4-cyclohexanedioic acid
- Authors: Adam, Muhammad Ameen
- Date: 2024-04
- Subjects: Chemical reactions , Chemistry, Organic , Bacteriology
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10948/63617 , vital:73562
- Description: The present investigation considered the host behaviour of three compounds, namely (+)-(2R,3R)-1,1,4,4-tetraphenylbutane-1,2,3,4-tetraol (H1), 1,1,4,4-tetraphenyl-1,4-butanediol (H2) and cyclohexane-1,4-diylbis(diphenylmethanol) (H3) in various guest mixtures. These host compounds were readily synthesized by means of Grignard addition reactions on the diesters of tartaric acid, succinic acid and 1,4-cyclohexanedioic acid. The guest mixtures included cyclopentanone, cyclohexanone, cycloheptanone and cyclooctanone, γ-butyrolactone, 2-pyrrolidone, N-methyl-2-pyrrolidone and N-ethyl-2-pyrrolidone, and pyridine, 2-methylpyridine, 3-methylpyridine and 4-methylpyridine. Crystals of (+)-(2R,3R)-1,1,4,4-tetraphenylbutane-1,2,3,4-tetraol (H1) were grown from cyclopentanone (5-ONE), cyclohexanone (6-ONE), cycloheptanone (7-ONE) and cyclooctanone (8-ONE,) producing 1:1 host:guest complexes in each instance. Thermal analysis showed the thermal stabilities of these complexes to be in the order 6-ONE > 7-ONE > 8-ONE > 5-ONE which correlated exactly with results from binary guest/guest competition experiments, where 6-ONE was always preferred by H1, while 5-ONE was consistently disfavoured. Single crystal X-ray diffraction (SCXRD) analyses demonstrated that each guest compound was retained in the crystals by means of a hydrogen bond with an alcohol moiety of the host compound. Furthermore, preferred guests 6- and 7-ONE produced crystals with greater densities than guests less favoured (5- and 8-ONE). A conformational analysis of the guest geometries in the four complexes with H1 revealed that the low energy guest conformers were present. The host selectivity for 6- and 7-ONE was proposed to be due to the improved molecular packing in the crystals of the complexes containing these two guest compounds, observed from their higher crystal densities. Hirshfeld surface analyses were not useful in explaining the preference of H1 for 6-ONE relative to 7-ONE (these types of analyses were not possible for the 5-ONE and 8-ONE-containing inclusion compounds due to the nature and degree of disorder present in the guest molecules). H1 was also crystallized from γ-butyrolactone (GBL), 2-pyrrolidone (NP), N-methyl-2-pyrrolidone (NMP) and N-ethyl-2-pyrrolidone (NEP), and 1H-NMR spectroscopy revealed that all but GBL were included. The host compound was also presented with these guest solvents in various mixtures, and it was observed that NMP was an extremely favoured guest solvent, followed by NEP and NP, with GBL being consistently disfavoured in every experiment. It was therefore shown that in certain instances, H1 may serve as an alternative tool for separating some of these mixtures through host-guest chemistry strategies. The hydrogen bonding motifs present in each of the successfully formed complexes were extensively investigated through SCXRD analysis, as was the thermal behaviour of these complexes. In the latter instance, the peak temperature of the endotherm (from the DSC trace) representing the guest release was greater for the inclusion compound with favoured NMP (145.5 °C) relative to the complexes with NP (139.8 °C) and NEP (120.5 °C). Host compounds H2 and H3 were revealed to have the ability to include each of pyridine (PYR), 2-methylpyridine (2MP), 3-methylpyridine (3MP) and 4-methylpyridine (4MP). H2 displayed selective behaviour for 3MP and 4MP when presented with mixtures of these guest compounds, whilst H3 preferred PYR. In the latter case, this PYR-containing inclusion compound was also the more stable one (the guest release onset temperature was highest, Ton 66.0 °C). It was demonstrated that H2 has the ability to separate very many binary mixtures of these pyridines on a practical platform, since K (the selectivity coefficient) values were 10 or greater in many instances. However, unfortunately, the more difficult-to-separate mixtures containing 3MP and 4MP cannot be purified or separated by employing H2 and supramolecular chemistry strategies. H3 was also shown to be a likely candidate for binary guest separations in very many of the guest solutions considered here, where K was also 10 or greater, and even infinity in many cases. SCXRD demonstrated that 2MP, 3MP and 4MP were retained in the crystals of their complexes by means of classical hydrogen bonds with the host compound. Satisfyingly, this hydrogen bond between 2MP and H2 (3.0213(18) Å) was significantly longer than that between this host compound and both disorder components of 3MP (2.875(2) and 2.825(9) Å) and that between H2 and 4MP (2.8458(13) Å). This observation explains the affinity of H2 for both 3MP and 4MP, and why 2MP was disfavoured. The results of thermal experiments did not wholly concur with observations from the guest/guest competition experiments. Hirshfeld surface analyses were also conducted but were not entirely conclusive with respect to explaining the host selectivity behaviour. In the case of H3, SCXRD analyses revealed that favoured PYR experienced a classical hydrogen bond with the host compound that was statistically significantly shorter (2.795(2) Å, 165°) than those between the other guest compounds and H3. Additionally, this guest compound was the only one to be involved in a (host)C−H···π(guest) interaction (2.91 Å, 139°) and also a non-classical hydrogen bond with the host compound ((host)C−H···N−C(guest), 2.77 Å (144°)). Finally, Hirshfeld surface analyses showed also that preferred PYR experienced a greater percentage of C···H/H···C (33.1%) and H···N/N···H (11.1%) interactions compared with the complexes with 2MP, 3MP and 4MP. However, it is not clear whether these Hirshfeld observations explain the affinity of H3 for PYR. , Thesis (MSc) -- Faculty of Science, School of Biomolecular & Chemical Sciences, 2024
- Full Text:
- Date Issued: 2024-04
- Authors: Adam, Muhammad Ameen
- Date: 2024-04
- Subjects: Chemical reactions , Chemistry, Organic , Bacteriology
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10948/63617 , vital:73562
- Description: The present investigation considered the host behaviour of three compounds, namely (+)-(2R,3R)-1,1,4,4-tetraphenylbutane-1,2,3,4-tetraol (H1), 1,1,4,4-tetraphenyl-1,4-butanediol (H2) and cyclohexane-1,4-diylbis(diphenylmethanol) (H3) in various guest mixtures. These host compounds were readily synthesized by means of Grignard addition reactions on the diesters of tartaric acid, succinic acid and 1,4-cyclohexanedioic acid. The guest mixtures included cyclopentanone, cyclohexanone, cycloheptanone and cyclooctanone, γ-butyrolactone, 2-pyrrolidone, N-methyl-2-pyrrolidone and N-ethyl-2-pyrrolidone, and pyridine, 2-methylpyridine, 3-methylpyridine and 4-methylpyridine. Crystals of (+)-(2R,3R)-1,1,4,4-tetraphenylbutane-1,2,3,4-tetraol (H1) were grown from cyclopentanone (5-ONE), cyclohexanone (6-ONE), cycloheptanone (7-ONE) and cyclooctanone (8-ONE,) producing 1:1 host:guest complexes in each instance. Thermal analysis showed the thermal stabilities of these complexes to be in the order 6-ONE > 7-ONE > 8-ONE > 5-ONE which correlated exactly with results from binary guest/guest competition experiments, where 6-ONE was always preferred by H1, while 5-ONE was consistently disfavoured. Single crystal X-ray diffraction (SCXRD) analyses demonstrated that each guest compound was retained in the crystals by means of a hydrogen bond with an alcohol moiety of the host compound. Furthermore, preferred guests 6- and 7-ONE produced crystals with greater densities than guests less favoured (5- and 8-ONE). A conformational analysis of the guest geometries in the four complexes with H1 revealed that the low energy guest conformers were present. The host selectivity for 6- and 7-ONE was proposed to be due to the improved molecular packing in the crystals of the complexes containing these two guest compounds, observed from their higher crystal densities. Hirshfeld surface analyses were not useful in explaining the preference of H1 for 6-ONE relative to 7-ONE (these types of analyses were not possible for the 5-ONE and 8-ONE-containing inclusion compounds due to the nature and degree of disorder present in the guest molecules). H1 was also crystallized from γ-butyrolactone (GBL), 2-pyrrolidone (NP), N-methyl-2-pyrrolidone (NMP) and N-ethyl-2-pyrrolidone (NEP), and 1H-NMR spectroscopy revealed that all but GBL were included. The host compound was also presented with these guest solvents in various mixtures, and it was observed that NMP was an extremely favoured guest solvent, followed by NEP and NP, with GBL being consistently disfavoured in every experiment. It was therefore shown that in certain instances, H1 may serve as an alternative tool for separating some of these mixtures through host-guest chemistry strategies. The hydrogen bonding motifs present in each of the successfully formed complexes were extensively investigated through SCXRD analysis, as was the thermal behaviour of these complexes. In the latter instance, the peak temperature of the endotherm (from the DSC trace) representing the guest release was greater for the inclusion compound with favoured NMP (145.5 °C) relative to the complexes with NP (139.8 °C) and NEP (120.5 °C). Host compounds H2 and H3 were revealed to have the ability to include each of pyridine (PYR), 2-methylpyridine (2MP), 3-methylpyridine (3MP) and 4-methylpyridine (4MP). H2 displayed selective behaviour for 3MP and 4MP when presented with mixtures of these guest compounds, whilst H3 preferred PYR. In the latter case, this PYR-containing inclusion compound was also the more stable one (the guest release onset temperature was highest, Ton 66.0 °C). It was demonstrated that H2 has the ability to separate very many binary mixtures of these pyridines on a practical platform, since K (the selectivity coefficient) values were 10 or greater in many instances. However, unfortunately, the more difficult-to-separate mixtures containing 3MP and 4MP cannot be purified or separated by employing H2 and supramolecular chemistry strategies. H3 was also shown to be a likely candidate for binary guest separations in very many of the guest solutions considered here, where K was also 10 or greater, and even infinity in many cases. SCXRD demonstrated that 2MP, 3MP and 4MP were retained in the crystals of their complexes by means of classical hydrogen bonds with the host compound. Satisfyingly, this hydrogen bond between 2MP and H2 (3.0213(18) Å) was significantly longer than that between this host compound and both disorder components of 3MP (2.875(2) and 2.825(9) Å) and that between H2 and 4MP (2.8458(13) Å). This observation explains the affinity of H2 for both 3MP and 4MP, and why 2MP was disfavoured. The results of thermal experiments did not wholly concur with observations from the guest/guest competition experiments. Hirshfeld surface analyses were also conducted but were not entirely conclusive with respect to explaining the host selectivity behaviour. In the case of H3, SCXRD analyses revealed that favoured PYR experienced a classical hydrogen bond with the host compound that was statistically significantly shorter (2.795(2) Å, 165°) than those between the other guest compounds and H3. Additionally, this guest compound was the only one to be involved in a (host)C−H···π(guest) interaction (2.91 Å, 139°) and also a non-classical hydrogen bond with the host compound ((host)C−H···N−C(guest), 2.77 Å (144°)). Finally, Hirshfeld surface analyses showed also that preferred PYR experienced a greater percentage of C···H/H···C (33.1%) and H···N/N···H (11.1%) interactions compared with the complexes with 2MP, 3MP and 4MP. However, it is not clear whether these Hirshfeld observations explain the affinity of H3 for PYR. , Thesis (MSc) -- Faculty of Science, School of Biomolecular & Chemical Sciences, 2024
- Full Text:
- Date Issued: 2024-04
Investigation of the synthesis and characterisation of spiro orthocarbonates and heterocyclic orthocarbonates
- Authors: Cuthbertson, Jarryd Pierre
- Date: 2024-04
- Subjects: Chemistry, Analytic , Analytical chemistry , Chemistry
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10948/63678 , vital:73578
- Description: A series of mostly asymmetrical spiro orthocarbonates and heterospirocyclic derivatives of orthocarbonic acid was synthesized from 2,2-dichlorobenzodioxole and a number of difunctional reagents. A systematic study of the size of the chelate rings formed around the spirocentric carbon atom was conducted by selecting representative samples of aliphatic and aromatic diols. The feasibility and scope of potential starting materials used was expanded by reacting DCBD successfully with thiols. Molecular structures of these compounds were confirmed using diffraction studies on single crystals. All compounds were analyzed using multinuclear NMR. DFT calculations performed on the compounds allowed for the development of equations that can accurately predict 13C chemical shifts of SOCs. Furthermore, the experimental NMR spectroscopy gave rise to an increment shift system for the 13C NMR shifts allowing for further assignment of carbon atom positions in compounds with multiple possible bonding patterns. , Thesis (MSc) -- Faculty of Science, School of Biomolecular & Chemical Sciences, 2024
- Full Text:
- Date Issued: 2024-04
- Authors: Cuthbertson, Jarryd Pierre
- Date: 2024-04
- Subjects: Chemistry, Analytic , Analytical chemistry , Chemistry
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10948/63678 , vital:73578
- Description: A series of mostly asymmetrical spiro orthocarbonates and heterospirocyclic derivatives of orthocarbonic acid was synthesized from 2,2-dichlorobenzodioxole and a number of difunctional reagents. A systematic study of the size of the chelate rings formed around the spirocentric carbon atom was conducted by selecting representative samples of aliphatic and aromatic diols. The feasibility and scope of potential starting materials used was expanded by reacting DCBD successfully with thiols. Molecular structures of these compounds were confirmed using diffraction studies on single crystals. All compounds were analyzed using multinuclear NMR. DFT calculations performed on the compounds allowed for the development of equations that can accurately predict 13C chemical shifts of SOCs. Furthermore, the experimental NMR spectroscopy gave rise to an increment shift system for the 13C NMR shifts allowing for further assignment of carbon atom positions in compounds with multiple possible bonding patterns. , Thesis (MSc) -- Faculty of Science, School of Biomolecular & Chemical Sciences, 2024
- Full Text:
- Date Issued: 2024-04
Learners’ understanding of their linguistic resources as a basis for learning natural sciences
- Authors: Thorne, Rochelle Eugenia
- Date: 2024-04
- Subjects: Linguistic analysis (Linguistics) , Science -- Study and teaching -- Methodology , Science -- Study and teaching (Elementary)
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10948/64049 , vital:73646
- Description: With eleven official languages, South Africa is known for its multilingual environment. Despite this, the country's educational system heavily favours English and Afrikaans. Despite the varied linguistic backgrounds of learners, English continues to be used as the Language of Learning and Teaching (LoLT), which raises questions regarding fair access to education. Within the context of South Africa's constitution and policy frameworks, particularly the Language in Education Policy (LiEP), this study aims to investigate how group work activities in a Natural Sciences classroom can give learners an opportunity to mobilise their multilingual repertoires. Three formerly Afrikaans-medium high schools in the Northern Areas of Gqeberha, were the sites for this research which focuses on Grade Nine Natural Sciences learners. Through the use of both quantitative and qualitative methods such as questionnaires, classroom observations, and focus groups, the study explores how learners make use of their language resources to navigate science instruction in English. The results contest the idea that languages are distinct entities and show that learners use language interchangeably as a learning tool, a practice known as translanguaging. Group work becomes an important space in which learners exercise agency in language selection, enabling the link of dialogical, multilingual, and cultural responses. Sociocultural theory offers insights into group work relationships and provides the theoretical foundation for understanding how learners use language to understand scientific topics. Building on Gibbons' mode continuum (2003), which maps the shifts in discourse in classroom contexts from every day talk at the “here and now” to more specialized talk, the study also explored an expanded continuum which aimed at clarifying the nuances of language and cognitive progression among learners working in collaborative groups. This study adds to the conversation about language ideologies by recognising the ideologies of inclusion, access and identity which informed learners’ thinking and attitudes to language choice in education. Thus, the study emphasises the importance of a sophisticated comprehension of multilingual repertoires in the classroom. In order to better accommodate the changing linguistic patterns of multilingual learners, the study recommends re-evaluating language policies and encouraging educators to exploit the potential of group work to develop understanding of scientific concepts. , Thesis (DPhil) -- Faculty of Education, School of Post Graduate Education, 2024
- Full Text:
- Date Issued: 2024-04
- Authors: Thorne, Rochelle Eugenia
- Date: 2024-04
- Subjects: Linguistic analysis (Linguistics) , Science -- Study and teaching -- Methodology , Science -- Study and teaching (Elementary)
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10948/64049 , vital:73646
- Description: With eleven official languages, South Africa is known for its multilingual environment. Despite this, the country's educational system heavily favours English and Afrikaans. Despite the varied linguistic backgrounds of learners, English continues to be used as the Language of Learning and Teaching (LoLT), which raises questions regarding fair access to education. Within the context of South Africa's constitution and policy frameworks, particularly the Language in Education Policy (LiEP), this study aims to investigate how group work activities in a Natural Sciences classroom can give learners an opportunity to mobilise their multilingual repertoires. Three formerly Afrikaans-medium high schools in the Northern Areas of Gqeberha, were the sites for this research which focuses on Grade Nine Natural Sciences learners. Through the use of both quantitative and qualitative methods such as questionnaires, classroom observations, and focus groups, the study explores how learners make use of their language resources to navigate science instruction in English. The results contest the idea that languages are distinct entities and show that learners use language interchangeably as a learning tool, a practice known as translanguaging. Group work becomes an important space in which learners exercise agency in language selection, enabling the link of dialogical, multilingual, and cultural responses. Sociocultural theory offers insights into group work relationships and provides the theoretical foundation for understanding how learners use language to understand scientific topics. Building on Gibbons' mode continuum (2003), which maps the shifts in discourse in classroom contexts from every day talk at the “here and now” to more specialized talk, the study also explored an expanded continuum which aimed at clarifying the nuances of language and cognitive progression among learners working in collaborative groups. This study adds to the conversation about language ideologies by recognising the ideologies of inclusion, access and identity which informed learners’ thinking and attitudes to language choice in education. Thus, the study emphasises the importance of a sophisticated comprehension of multilingual repertoires in the classroom. In order to better accommodate the changing linguistic patterns of multilingual learners, the study recommends re-evaluating language policies and encouraging educators to exploit the potential of group work to develop understanding of scientific concepts. , Thesis (DPhil) -- Faculty of Education, School of Post Graduate Education, 2024
- Full Text:
- Date Issued: 2024-04
Lion and leopard diet and dispersal in human-dominated landscapes
- Authors: Forbes, Ryan Edward
- Date: 2024-04
- Subjects: Carnivora -- South Africa , Carnivorous animals -- Conservation , Carnivorous animals -- Ecology
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10948/63766 , vital:73596
- Description: Terrestrial carnivore population declines are driven by habitat loss and fragmentation, prey-depletion, persecution, and retaliatory killings. Population strongholds now centre on protected areas, that face increasing human pressure, resulting in population isolation, declining prey populations, and livestock intrusion. I therefore aimed to investigate dispersal and connectivity, and diets of lions (Panthera leo) and leopards (P. pardus) in response to human-use and wildlife density gradients in the Greater Limpopo Transfrontier Conservation Area (GLTCA). Firstly, I investigated dispersal and connectivity for these carnivores across the GLTCA, using single nucleotide polymorphisms. I present evidence that in the prey-depleted Mozambique portion of the GLTCA, lion and leopard dispersal distances are higher compared with the prey-abundant Kruger National Park (KNP). I also provide the first evidence for long-range dispersal in female lions. Despite evidence for connectivity occurring across the GLTCA, I recorded population structuring across the region for both carnivores, likely due to habitat fragmentation by human activities in the Mozambique portion of the GLTCA. I then assessed carnivore diet responses to prey depletion and livestock availability by comparing lion and leopard diets in the prey-abundant/livestock-absent KNP (South Africa), with the prey-depleted/livestock-abundant Limpopo National Park (LNP, Mozambique), using scat analyses. Lions and leopards downshifted their prey size selection in LNP relative to KNP. Despite both carnivores expanding their dietary niche breadths in LNP relative to KNP, diet overlap did not differ between sites. This suggests that even when prey is depleted, lions and leopards can partition food resources, which likely limits competition. Despite cattle (Bos taurus) being the most abundant ungulate in LNP, lions and leopards strongly avoided cattle, supporting the notion that carnivores can perceive the risk of hunting livestock and modulate their foraging behaviour to reduce human-carnivore conflict. Should my findings reflect general patterns in carnivore dispersal and diet responses to human-use and wildlife gradients, then carnivore conservation initiates across their range should focus on prey population rehabilitation, improved livestock husbandry practices, the establishment of effective dispersal corridors and improved human-tolerance towards large carnivores. , Thesis (MSc) -- Faculty of Science, School of Environmental Sciences, 2024
- Full Text:
- Date Issued: 2024-04
- Authors: Forbes, Ryan Edward
- Date: 2024-04
- Subjects: Carnivora -- South Africa , Carnivorous animals -- Conservation , Carnivorous animals -- Ecology
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10948/63766 , vital:73596
- Description: Terrestrial carnivore population declines are driven by habitat loss and fragmentation, prey-depletion, persecution, and retaliatory killings. Population strongholds now centre on protected areas, that face increasing human pressure, resulting in population isolation, declining prey populations, and livestock intrusion. I therefore aimed to investigate dispersal and connectivity, and diets of lions (Panthera leo) and leopards (P. pardus) in response to human-use and wildlife density gradients in the Greater Limpopo Transfrontier Conservation Area (GLTCA). Firstly, I investigated dispersal and connectivity for these carnivores across the GLTCA, using single nucleotide polymorphisms. I present evidence that in the prey-depleted Mozambique portion of the GLTCA, lion and leopard dispersal distances are higher compared with the prey-abundant Kruger National Park (KNP). I also provide the first evidence for long-range dispersal in female lions. Despite evidence for connectivity occurring across the GLTCA, I recorded population structuring across the region for both carnivores, likely due to habitat fragmentation by human activities in the Mozambique portion of the GLTCA. I then assessed carnivore diet responses to prey depletion and livestock availability by comparing lion and leopard diets in the prey-abundant/livestock-absent KNP (South Africa), with the prey-depleted/livestock-abundant Limpopo National Park (LNP, Mozambique), using scat analyses. Lions and leopards downshifted their prey size selection in LNP relative to KNP. Despite both carnivores expanding their dietary niche breadths in LNP relative to KNP, diet overlap did not differ between sites. This suggests that even when prey is depleted, lions and leopards can partition food resources, which likely limits competition. Despite cattle (Bos taurus) being the most abundant ungulate in LNP, lions and leopards strongly avoided cattle, supporting the notion that carnivores can perceive the risk of hunting livestock and modulate their foraging behaviour to reduce human-carnivore conflict. Should my findings reflect general patterns in carnivore dispersal and diet responses to human-use and wildlife gradients, then carnivore conservation initiates across their range should focus on prey population rehabilitation, improved livestock husbandry practices, the establishment of effective dispersal corridors and improved human-tolerance towards large carnivores. , Thesis (MSc) -- Faculty of Science, School of Environmental Sciences, 2024
- Full Text:
- Date Issued: 2024-04
Mathematical modelling of the tumour treatment with chemotherapy
- Authors: Nyaweni, Fundile Sindy
- Date: 2024-04
- Subjects: Mathematical models , Mathematics , Chemotherapy
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10948/64289 , vital:73672
- Description: In this study, a cancer disease model incorporating predator-prey dynamics between immune cells and tumor cells, as well as competition between tumor cells and normal cells, is formulated in an attempt to understand the interaction dynamics that govern the complex interplay within the tumor microenvironment. Mathematical analysis is employed to derive conditions for the boundedness of solutions and to discuss disease thresholds such as the basic reproduction number, R0. Equilibrium points are identified, and stability conditions for the system are derived. Sensitivity analysis is used to assess uncertainties in the parameters of the model, specifically their impact on R0. Numerical simulations are conducted, utilizing the Runge-Kutta scheme to solve the model. Furthermore, optimal control (OC) techniques are applied to examine the role of chemotherapy in enhancing tumor cell elimination and minimizing adverse effects on immune cells and normal cells. The improved model, incorporating normal cells, anticancer drugs, and immune cells, allows for a more comprehensive analysis of the dynamic interactions within the biological system. The optimal control is determined using the forward-backward sweep numerical method. The numerical simulation is carried out in MATLAB to validate and complement the analytical findings. The results indicate that a low concentration of the drug leads to a prolonged period for tumor clearance. Conversely, a higher drug concentration results in quicker tumor clearance, albeit with adverse effects on normal and effector cells. The OC identifies when to stop the treatment once the tumor clears. Furthermore, OC facilitates the regeneration of normal and immune cells beyond treatment, in contrast to a control scenario without optimization. The findings highlight the importance of early detection and careful chemotherapy dosage selection for effective and personalized cancer treatment strategies. , Thesis (MSc) -- Faculty of Science, School Computer Science, Mathematics, Physics and Statistics, 2024
- Full Text:
- Date Issued: 2024-04
- Authors: Nyaweni, Fundile Sindy
- Date: 2024-04
- Subjects: Mathematical models , Mathematics , Chemotherapy
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10948/64289 , vital:73672
- Description: In this study, a cancer disease model incorporating predator-prey dynamics between immune cells and tumor cells, as well as competition between tumor cells and normal cells, is formulated in an attempt to understand the interaction dynamics that govern the complex interplay within the tumor microenvironment. Mathematical analysis is employed to derive conditions for the boundedness of solutions and to discuss disease thresholds such as the basic reproduction number, R0. Equilibrium points are identified, and stability conditions for the system are derived. Sensitivity analysis is used to assess uncertainties in the parameters of the model, specifically their impact on R0. Numerical simulations are conducted, utilizing the Runge-Kutta scheme to solve the model. Furthermore, optimal control (OC) techniques are applied to examine the role of chemotherapy in enhancing tumor cell elimination and minimizing adverse effects on immune cells and normal cells. The improved model, incorporating normal cells, anticancer drugs, and immune cells, allows for a more comprehensive analysis of the dynamic interactions within the biological system. The optimal control is determined using the forward-backward sweep numerical method. The numerical simulation is carried out in MATLAB to validate and complement the analytical findings. The results indicate that a low concentration of the drug leads to a prolonged period for tumor clearance. Conversely, a higher drug concentration results in quicker tumor clearance, albeit with adverse effects on normal and effector cells. The OC identifies when to stop the treatment once the tumor clears. Furthermore, OC facilitates the regeneration of normal and immune cells beyond treatment, in contrast to a control scenario without optimization. The findings highlight the importance of early detection and careful chemotherapy dosage selection for effective and personalized cancer treatment strategies. , Thesis (MSc) -- Faculty of Science, School Computer Science, Mathematics, Physics and Statistics, 2024
- Full Text:
- Date Issued: 2024-04
Mindsets of change agents for development: a case study of the Sundays River Valley, Eastern Cape
- Bezuidenhout, Theo Gerhardus
- Authors: Bezuidenhout, Theo Gerhardus
- Date: 2024-04
- Subjects: Social change , Sustainable development -- South Africa , Well-being , Economic development -- Social aspects
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10948/64874 , vital:73937
- Description: Societal development in underdeveloped areas is a process of enhancing and improving the quality of life in communities, with a focus on meeting their social, economic, environmental, and political needs. Despite ideological efforts and growing interest in movements, mobilisations and communities promoting social change, little research has been done on the mindsets of change agents. Margaret Archer’s (1988), Morphogenetic Approach to social development has been used in this case as a theoretical framework emphasising that social change and development occur through interactions between individuals and their social environments. This approach focusses on the importance of feedback loops, where changes in the environment and the reactions of individuals to these changes both influence and are influenced by one another. Through reflective learning, semistructured interviews and document analysis, the dissertation explored research questions concerning different perspectives of change agents in the Sundays River Valley. The theories examined provide options of theoretical frameworks which can be used to assess and evaluate the work and role of change agents to participate in societal development. This is important in the Sundays River Valley context as, up to now, there has been no shortage or lack of development plans and policies for the area. Rather, what has been absent is the theoretical frameworks to provide the context and meaning for change agents to participate in societal development and occupy their role in the various development plans and policies. Collaborative development and participation acknowledge that solving complex social problems requires the efforts of multiple organisations, individuals, and generations. To enable societal development requires social trust and cooperation of multiple stakeholders, including government, community members, businesses, development agencies, non-governmental organisations and educational institutions. , Thesis (MA) -- Faculty of Business and Economic Sciences, School of Economics, Development and Tourism , 2024
- Full Text:
- Date Issued: 2024-04
- Authors: Bezuidenhout, Theo Gerhardus
- Date: 2024-04
- Subjects: Social change , Sustainable development -- South Africa , Well-being , Economic development -- Social aspects
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10948/64874 , vital:73937
- Description: Societal development in underdeveloped areas is a process of enhancing and improving the quality of life in communities, with a focus on meeting their social, economic, environmental, and political needs. Despite ideological efforts and growing interest in movements, mobilisations and communities promoting social change, little research has been done on the mindsets of change agents. Margaret Archer’s (1988), Morphogenetic Approach to social development has been used in this case as a theoretical framework emphasising that social change and development occur through interactions between individuals and their social environments. This approach focusses on the importance of feedback loops, where changes in the environment and the reactions of individuals to these changes both influence and are influenced by one another. Through reflective learning, semistructured interviews and document analysis, the dissertation explored research questions concerning different perspectives of change agents in the Sundays River Valley. The theories examined provide options of theoretical frameworks which can be used to assess and evaluate the work and role of change agents to participate in societal development. This is important in the Sundays River Valley context as, up to now, there has been no shortage or lack of development plans and policies for the area. Rather, what has been absent is the theoretical frameworks to provide the context and meaning for change agents to participate in societal development and occupy their role in the various development plans and policies. Collaborative development and participation acknowledge that solving complex social problems requires the efforts of multiple organisations, individuals, and generations. To enable societal development requires social trust and cooperation of multiple stakeholders, including government, community members, businesses, development agencies, non-governmental organisations and educational institutions. , Thesis (MA) -- Faculty of Business and Economic Sciences, School of Economics, Development and Tourism , 2024
- Full Text:
- Date Issued: 2024-04
Modelling offsite construction to control hazards and direct cost of accidents
- Simukonda, Wakisa Tulombolombo
- Authors: Simukonda, Wakisa Tulombolombo
- Date: 2024-04
- Subjects: Construction industry -- Accidents , Construction industry -- Risk management , Building -- Safety measures
- Language: English
- Type: Doctotal theses , text
- Identifier: http://hdl.handle.net/10948/64818 , vital:73923
- Description: The construction industry contributes significantly to the growth of developed and emerging economies. The industry contributes a sizeable proportion of Gross Domestic Product and Gross National Product. However, the poor safety performance of the industry and its consequential socio-economic impact threatens the industry’s significant contributions. It is for this reason that off-site construction has been identified as a sine qua non for addressing poor safety performance. The application of design for manufacture and assembly and lean techniques in the manufacture and assembly processes of off-site construction is suggested to minimise safety hazards in construction. The research was conducted to establish the relevant design for manufacture and assembly and lean techniques for addressing safety hazards in off-site construction and to develop a conceptual model of off-site construction for controlling hazards and direct costs of accidents to protect people and profits in construction. A preliminary conceptual model of off-site construction was initially devised based on a literature review and later refined into a developed conceptual model of off-site construction using findings from the qualitative phase of the study. The confirmation of the relationships and concepts presented in the developed conceptual model of off-site construction was based on the findings from quantitative data. The quantitative data were analysed using the Statistical Package for Social Science (SPSS) Version 26. Within SPSS, descriptive and inferential statistics were used to examine the relationships between off-site construction methods and safety issues, while Cronbach’s alpha was used to measure the validity of the findings. Based on the findings of the study, significant safety benefits of off-site construction methods of design for manufacture and assembly and lean techniques were identified. The benefits relate to the elimination of safety hazards including lack of personal protective equipment, work at height, poor work methods, poor house-keeping and lack of training and experience. Furthermore, the research findings indicated that implementing design for manufacture and assembly and lean practices limits direct costs of accidents, including costs expended on wages and medical bills. The positive outcomes of applying design for manufacture and assembly and lean techniques include better project management and working conditions, improved quality, minimised construction waste, and increased productivity. Factors impeding application of design for manufacture and assembly and lean techniques within contracting organisations include lack of stakeholder collaboration, a conservative mind-set towards traditional construction, lack of preferential policies and expensive logistics. These challenges can be addressed by promoting awareness of off-site construction methods, capacity-building, establishing a robust local supply chain and the involvement of government in creating an enabling political and legal environment, among others. Based on the research, an integrated conceptual model of off-site construction was developed for using off-site construction to control hazards and direct costs of accidents to protect people and profits in construction. In essence, the model can be used to identify design for manufacture and assembly and lean practices applicable in off-site construction projects to control potential safety hazards and risks. Identification and application of appropriate design for manufacture and assembly and lean practices, while addressing safety challenges, would result in the elimination of safety hazards and direct costs associated with the occurrence of accidents. Consequently, prevention of accidents would ensure the safety and health of people in construction, while the reduction of direct costs of accidents would improve the profitability margins of contracting organisations. Based on the study, recommendations are made for wider adoption of off-site construction as a modern construction method, and application of design for manufacture and assembly and lean techniques in off-site construction as strategic, industry and national, initiatives for improving safety in the construction industry. , Thesis (DPhil) -- Faculty ofEngineering, the Built Environment, and Technology, School of Built Environment and Civil Engineering, 2024
- Full Text:
- Date Issued: 2024-04
- Authors: Simukonda, Wakisa Tulombolombo
- Date: 2024-04
- Subjects: Construction industry -- Accidents , Construction industry -- Risk management , Building -- Safety measures
- Language: English
- Type: Doctotal theses , text
- Identifier: http://hdl.handle.net/10948/64818 , vital:73923
- Description: The construction industry contributes significantly to the growth of developed and emerging economies. The industry contributes a sizeable proportion of Gross Domestic Product and Gross National Product. However, the poor safety performance of the industry and its consequential socio-economic impact threatens the industry’s significant contributions. It is for this reason that off-site construction has been identified as a sine qua non for addressing poor safety performance. The application of design for manufacture and assembly and lean techniques in the manufacture and assembly processes of off-site construction is suggested to minimise safety hazards in construction. The research was conducted to establish the relevant design for manufacture and assembly and lean techniques for addressing safety hazards in off-site construction and to develop a conceptual model of off-site construction for controlling hazards and direct costs of accidents to protect people and profits in construction. A preliminary conceptual model of off-site construction was initially devised based on a literature review and later refined into a developed conceptual model of off-site construction using findings from the qualitative phase of the study. The confirmation of the relationships and concepts presented in the developed conceptual model of off-site construction was based on the findings from quantitative data. The quantitative data were analysed using the Statistical Package for Social Science (SPSS) Version 26. Within SPSS, descriptive and inferential statistics were used to examine the relationships between off-site construction methods and safety issues, while Cronbach’s alpha was used to measure the validity of the findings. Based on the findings of the study, significant safety benefits of off-site construction methods of design for manufacture and assembly and lean techniques were identified. The benefits relate to the elimination of safety hazards including lack of personal protective equipment, work at height, poor work methods, poor house-keeping and lack of training and experience. Furthermore, the research findings indicated that implementing design for manufacture and assembly and lean practices limits direct costs of accidents, including costs expended on wages and medical bills. The positive outcomes of applying design for manufacture and assembly and lean techniques include better project management and working conditions, improved quality, minimised construction waste, and increased productivity. Factors impeding application of design for manufacture and assembly and lean techniques within contracting organisations include lack of stakeholder collaboration, a conservative mind-set towards traditional construction, lack of preferential policies and expensive logistics. These challenges can be addressed by promoting awareness of off-site construction methods, capacity-building, establishing a robust local supply chain and the involvement of government in creating an enabling political and legal environment, among others. Based on the research, an integrated conceptual model of off-site construction was developed for using off-site construction to control hazards and direct costs of accidents to protect people and profits in construction. In essence, the model can be used to identify design for manufacture and assembly and lean practices applicable in off-site construction projects to control potential safety hazards and risks. Identification and application of appropriate design for manufacture and assembly and lean practices, while addressing safety challenges, would result in the elimination of safety hazards and direct costs associated with the occurrence of accidents. Consequently, prevention of accidents would ensure the safety and health of people in construction, while the reduction of direct costs of accidents would improve the profitability margins of contracting organisations. Based on the study, recommendations are made for wider adoption of off-site construction as a modern construction method, and application of design for manufacture and assembly and lean techniques in off-site construction as strategic, industry and national, initiatives for improving safety in the construction industry. , Thesis (DPhil) -- Faculty ofEngineering, the Built Environment, and Technology, School of Built Environment and Civil Engineering, 2024
- Full Text:
- Date Issued: 2024-04
Multi-purpose community centres as catalysts for socio-economic development in Eastern Cape province, South Africa
- Gobe, Cynthia Bongiwe Ntombikayise
- Authors: Gobe, Cynthia Bongiwe Ntombikayise
- Date: 2024-04
- Subjects: Community centers -- South Africa , Buildings -- Environmental engineering -- South Africa , Sustainable construction -- Economic aspects , Infrastructure (Economics) -- South Africa Sustainable development
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10948/64533 , vital:73747
- Description: The central issue facing African society, especially underdeveloped countries is that most of the population lives below the poverty line, experiences high levels of unemployment and unsustainable livelihoods. The poor and marginalised groups in many communities are deprived access to infrastructure and socio-economic amenities, this includes accessibility to government services, information, and developmental opportunities. The development of Multi-purpose Community Centres (MPCCs) is viewed as a value-adding solution to several challenges facing unequal societies, such as inadequate infrastructure, remote settlement patterns, poor access to basic services, poor access to technology, poor access to information, increased unemployment rate, increased poverty rate, and many others. The study examines the socio-economic impact of MPCCs on municipalities of the Eastern Cape Province in South Africa and explores how these centres, as built environment outputs can become a stimulus for sustainable livelihoods in urban, rural, and peri-urban human settlements, including informal settlements. The study falls under implementation evaluation research methodologies which assesses whether a programme has been adequately implemented before making inference on its effectiveness. Anchored in a Social Constructivism knowledge paradigm and leaning on a Systems and Development Theories, the study adopted a Mixed Method Research approach. In view of the data required document reviews, field observations, interviews and questionnaire surveys were employed. The research findings revealed that despite the delivery of MPCCs by the Department of Human Settlements, these centers have not provided much socio-economic opportunities to members of the communities where they are built. The MPCCs under study are facing many challenges that render them ineffective to fulfill their mandate of improving the lives of residents. The study yielded an inclusive and responsive human settlements development model for the creation of well-functioning socio-economic impactful MPCCs within existing and forth-coming housing projects and informal settlements. , Thesis (DPhil) -- Faculty of Engineering, the Built Environment, and Technology, School of Built Environment and Civil Engineering, 2024
- Full Text:
- Date Issued: 2024-04
- Authors: Gobe, Cynthia Bongiwe Ntombikayise
- Date: 2024-04
- Subjects: Community centers -- South Africa , Buildings -- Environmental engineering -- South Africa , Sustainable construction -- Economic aspects , Infrastructure (Economics) -- South Africa Sustainable development
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10948/64533 , vital:73747
- Description: The central issue facing African society, especially underdeveloped countries is that most of the population lives below the poverty line, experiences high levels of unemployment and unsustainable livelihoods. The poor and marginalised groups in many communities are deprived access to infrastructure and socio-economic amenities, this includes accessibility to government services, information, and developmental opportunities. The development of Multi-purpose Community Centres (MPCCs) is viewed as a value-adding solution to several challenges facing unequal societies, such as inadequate infrastructure, remote settlement patterns, poor access to basic services, poor access to technology, poor access to information, increased unemployment rate, increased poverty rate, and many others. The study examines the socio-economic impact of MPCCs on municipalities of the Eastern Cape Province in South Africa and explores how these centres, as built environment outputs can become a stimulus for sustainable livelihoods in urban, rural, and peri-urban human settlements, including informal settlements. The study falls under implementation evaluation research methodologies which assesses whether a programme has been adequately implemented before making inference on its effectiveness. Anchored in a Social Constructivism knowledge paradigm and leaning on a Systems and Development Theories, the study adopted a Mixed Method Research approach. In view of the data required document reviews, field observations, interviews and questionnaire surveys were employed. The research findings revealed that despite the delivery of MPCCs by the Department of Human Settlements, these centers have not provided much socio-economic opportunities to members of the communities where they are built. The MPCCs under study are facing many challenges that render them ineffective to fulfill their mandate of improving the lives of residents. The study yielded an inclusive and responsive human settlements development model for the creation of well-functioning socio-economic impactful MPCCs within existing and forth-coming housing projects and informal settlements. , Thesis (DPhil) -- Faculty of Engineering, the Built Environment, and Technology, School of Built Environment and Civil Engineering, 2024
- Full Text:
- Date Issued: 2024-04
Numerical modelling of power law constants established through impression and micro-Uniaxial creep methods for service exposed A234WPB steel
- Authors: Tembo, Blessed
- Date: 2024-04
- Subjects: Number theory , Numerical analysis , Mechanical engineering
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10948/64852 , vital:73931
- Description: Continuous monitoring of creep life in materials operating at high temperatures and pressures is imperative to prevent catastrophic failures and ensure timely replacement of worn-out components in industrial plants. Small-scale creep testing methodologies offer a valuable means of assessing material creep life while preserving structural integrity. Motivated by the need for reliable methods in creep life assessment, this study aimed to investigate the creep properties of A234WPB material subjected to service conditions using Impression creep and micro-uniaxial creep testing techniques. The research questions focused on establishing power law constants through small-scale creep testing, validating these constants using numerical modelling, and assessing their practical implementation in predicting material creep life. Samples extracted from service-exposed A234WPB steel alloy underwent step-load impression creep tests and step-temperature micro-uniaxial creep tests to derive the power law creep equation. The determined stress exponent of 3.967 indicated that dislocation creep was the dominant creep-controlling mechanism at 520 °C. A numerical model, utilizing the established power law constants, demonstrated a strong correlation with experimental findings in steady-state creep rates. Furthermore, the conventional Monkman-Grant approach was employed to predict the remaining life of the service-exposed material using impression creep data. The predicted remaining life aligned with the scatter band of uniaxial rupture life on a Larson-Miller plot, highlighting the practical utility of impression creep and micro-uniaxial creep testing techniques in assessing creep life. This study contributes to the advancement of small-scale creep testing methods and underscores their potential for practical implementation in industrial settings, thereby enhancing the reliability and safety of high-temperature and high-pressure operations. , Thesis (MEng) -- Faculty of Engineering, the Built Environment, and Technology, School of Engineering, 2024
- Full Text:
- Date Issued: 2024-04
- Authors: Tembo, Blessed
- Date: 2024-04
- Subjects: Number theory , Numerical analysis , Mechanical engineering
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10948/64852 , vital:73931
- Description: Continuous monitoring of creep life in materials operating at high temperatures and pressures is imperative to prevent catastrophic failures and ensure timely replacement of worn-out components in industrial plants. Small-scale creep testing methodologies offer a valuable means of assessing material creep life while preserving structural integrity. Motivated by the need for reliable methods in creep life assessment, this study aimed to investigate the creep properties of A234WPB material subjected to service conditions using Impression creep and micro-uniaxial creep testing techniques. The research questions focused on establishing power law constants through small-scale creep testing, validating these constants using numerical modelling, and assessing their practical implementation in predicting material creep life. Samples extracted from service-exposed A234WPB steel alloy underwent step-load impression creep tests and step-temperature micro-uniaxial creep tests to derive the power law creep equation. The determined stress exponent of 3.967 indicated that dislocation creep was the dominant creep-controlling mechanism at 520 °C. A numerical model, utilizing the established power law constants, demonstrated a strong correlation with experimental findings in steady-state creep rates. Furthermore, the conventional Monkman-Grant approach was employed to predict the remaining life of the service-exposed material using impression creep data. The predicted remaining life aligned with the scatter band of uniaxial rupture life on a Larson-Miller plot, highlighting the practical utility of impression creep and micro-uniaxial creep testing techniques in assessing creep life. This study contributes to the advancement of small-scale creep testing methods and underscores their potential for practical implementation in industrial settings, thereby enhancing the reliability and safety of high-temperature and high-pressure operations. , Thesis (MEng) -- Faculty of Engineering, the Built Environment, and Technology, School of Engineering, 2024
- Full Text:
- Date Issued: 2024-04