Microalgae as indicators of environmental change in the St Lucia estuarine system
- Authors: Nunes, Monique
- Date: 2019
- Subjects: Microalgae -- South Africa -- St Lucia estuarine
- Language: English
- Type: Thesis , Doctoral , DPhil
- Identifier: http://hdl.handle.net/10948/31165 , vital:31333
- Description: The St Lucia system represents 56% of the estuarine habitat area in South Africa. This dynamic estuarine lake responds to a complex interaction of climatic and anthropogenic drivers. There has been a long history of human interventions and the extended drought (2002-2012) led to major changes. In 1952, the inlet shared between the estuarine system and the Mfolozi River was artificially separated, which significantly reduced freshwater inflow. The systems were separated because of the silt load from the expanding agricultural activities in the Mfolozi River catchment. The drought prompted a critical review of re-establishing the historic connection, and in July 2012, the beach spillway was excavated marking the start of restoring connectivity. Increased rainfall coupled with the partial re-connection with the agriculturally-impacted Mfolozi River shifted the St Lucia estuarine system to a new wet phase. This study investigated the microalgal dynamics of the estuarine system as it transitioned to this new wet phase. Results showed that the phytoplankton and microphytobenthos (MPB) biomass was low (< 5 ug l-1 and < 60 mg m-2 respectively) throughout the system due to nutrient and light availability, water residence time and sediment type. The increased freshwater inflow from the Mfolozi River was limited to the Narrows and available nutrients promoted the growth of cyanobacteria and dinophytes in the water column. Of interest was the presence of the potentially harmful algal species Prorocentrum minimum. A weekly study investigated the relationship between freshwater inflow, phytoplankton succession and the introduction and persistence of harmful microalgal species in the lower reaches. The increased freshwater inflow received from the Mfolozi River has led to a system in a constant state of flux. The changes in salinity, light availability and water residence time, shifted the phytoplankton functional group structure to one where chlorophytes and euglenoids were dominant. The persistence of the nutrient tolerant euglenoids highlighted the influence of the nutrient-enriched freshwater inflow on the phytoplankton functional groups. However, the relative abundance of all functional groups remained low due to the rapid change in environmental conditions. The next step was to test the use of an artificial substrate as a monitoring method to detect nutrient induced change. Findings from the 28-day study showed that epilithic diatom communities growing on glass slides were good indicators of nutrient enrichment. The epilithic algal biomass increased significantly from 1.5 mg m-2 (Day 14) to 6 mg m-2 (Day 21), following peak river inflow. In contrast, the phytoplankton and MPB showed no discernible increase in biomass. Epilithic diatom community diversity, richness and evenness scores declined due to the increasing relative abundance of a single nutrient tolerant species, Cocconeis placentula var. euglypta. The use of diatoms as indicators of change depends on the accuracy of identification to species level. This can be a slow process requiring a high level of taxonomic expertise. Considering that molecular phylogenetic methods are readily used to produce a reliable taxonomic list, the suitability of DNA metabarcoding for diatom monitoring in the St Lucia Estuary was tested. Comparisons between the molecular and morphological method indicated that the diatom taxonomic composition was similar at 9 to 27% for genus level and 2 to 9% at species level. The low taxonomic similarity was related to the large number of unclassified DNA representative sequences included in the molecular inventory due to the incomplete DNA library database. However, the available operational taxonomic units (OTUs) from the molecular method did provide an effective alternative to determine the relevant community diversity estimates required for the application of the South African Estuarine Health Index (EHI). This research has highlighted the dynamic nature of the St Lucia estuarine system and the effectiveness of the microalgal communities to differentiate between the cyclical climatic phases and anthropogenic stressors such as nutrient enrichment.
- Full Text:
- Date Issued: 2019
- Authors: Nunes, Monique
- Date: 2019
- Subjects: Microalgae -- South Africa -- St Lucia estuarine
- Language: English
- Type: Thesis , Doctoral , DPhil
- Identifier: http://hdl.handle.net/10948/31165 , vital:31333
- Description: The St Lucia system represents 56% of the estuarine habitat area in South Africa. This dynamic estuarine lake responds to a complex interaction of climatic and anthropogenic drivers. There has been a long history of human interventions and the extended drought (2002-2012) led to major changes. In 1952, the inlet shared between the estuarine system and the Mfolozi River was artificially separated, which significantly reduced freshwater inflow. The systems were separated because of the silt load from the expanding agricultural activities in the Mfolozi River catchment. The drought prompted a critical review of re-establishing the historic connection, and in July 2012, the beach spillway was excavated marking the start of restoring connectivity. Increased rainfall coupled with the partial re-connection with the agriculturally-impacted Mfolozi River shifted the St Lucia estuarine system to a new wet phase. This study investigated the microalgal dynamics of the estuarine system as it transitioned to this new wet phase. Results showed that the phytoplankton and microphytobenthos (MPB) biomass was low (< 5 ug l-1 and < 60 mg m-2 respectively) throughout the system due to nutrient and light availability, water residence time and sediment type. The increased freshwater inflow from the Mfolozi River was limited to the Narrows and available nutrients promoted the growth of cyanobacteria and dinophytes in the water column. Of interest was the presence of the potentially harmful algal species Prorocentrum minimum. A weekly study investigated the relationship between freshwater inflow, phytoplankton succession and the introduction and persistence of harmful microalgal species in the lower reaches. The increased freshwater inflow received from the Mfolozi River has led to a system in a constant state of flux. The changes in salinity, light availability and water residence time, shifted the phytoplankton functional group structure to one where chlorophytes and euglenoids were dominant. The persistence of the nutrient tolerant euglenoids highlighted the influence of the nutrient-enriched freshwater inflow on the phytoplankton functional groups. However, the relative abundance of all functional groups remained low due to the rapid change in environmental conditions. The next step was to test the use of an artificial substrate as a monitoring method to detect nutrient induced change. Findings from the 28-day study showed that epilithic diatom communities growing on glass slides were good indicators of nutrient enrichment. The epilithic algal biomass increased significantly from 1.5 mg m-2 (Day 14) to 6 mg m-2 (Day 21), following peak river inflow. In contrast, the phytoplankton and MPB showed no discernible increase in biomass. Epilithic diatom community diversity, richness and evenness scores declined due to the increasing relative abundance of a single nutrient tolerant species, Cocconeis placentula var. euglypta. The use of diatoms as indicators of change depends on the accuracy of identification to species level. This can be a slow process requiring a high level of taxonomic expertise. Considering that molecular phylogenetic methods are readily used to produce a reliable taxonomic list, the suitability of DNA metabarcoding for diatom monitoring in the St Lucia Estuary was tested. Comparisons between the molecular and morphological method indicated that the diatom taxonomic composition was similar at 9 to 27% for genus level and 2 to 9% at species level. The low taxonomic similarity was related to the large number of unclassified DNA representative sequences included in the molecular inventory due to the incomplete DNA library database. However, the available operational taxonomic units (OTUs) from the molecular method did provide an effective alternative to determine the relevant community diversity estimates required for the application of the South African Estuarine Health Index (EHI). This research has highlighted the dynamic nature of the St Lucia estuarine system and the effectiveness of the microalgal communities to differentiate between the cyclical climatic phases and anthropogenic stressors such as nutrient enrichment.
- Full Text:
- Date Issued: 2019
Microstructural evolution of welded creep aged 12% cr martensitic stainless steel
- Authors: Marx, Genevéve
- Date: 2019
- Subjects: Stainless steel -- Welding
- Language: English
- Type: Thesis , Doctoral , DPhil
- Identifier: http://hdl.handle.net/10948/30766 , vital:31128
- Description: Tempered martensite ferritic (TMF) steels with 9-12% Cr additions are used extensively for high-pressure steam pipes in coal-fired power plants. They operate at temperatures above 500ºC and are consequently susceptible to creep damage. Due to economic reasons, welding must be performed on service exposed materials when a component needs to be replaced. Fusion welding results in the formation of different microstructural regions within the weldment. The primary failure mechanism of TMF steel welded components is Type IV cracking that results from accelerated void formation in the fine-grained heat affected zone (FGHAZ) during creep. Short-term creep-tests performed across weldments made on new and service exposed steels have shown that the weldment consistently fails in the FGHAZ of the service exposed material. This observation has not yet been fully explained since not much is known about the microstructural evolution of creep aged material during welding. Thus, further investigation on the microstructure of welded creep aged material is warranted. The main aim of this thesis was to investigate the microstructural evolution when welding upon creep aged 9-12% Cr martensitic steels using advanced electron microscopy techniques. X20CrMoV12-1 (12% Cr) in the virgin and long-term service-exposed state were investigated. GleebleTM weld simulation of the FGHAZ was performed on the materials. Detailed microstructural investigations were conducted on the parent and simulated FGHAZ materials to analyse the voids, dislocation density, micro-grains, and precipitates (M23C6, MX, Laves, Z-phase) in the materials. Light Microscopy (LM) and Scanning Electron Microscopy (SEM) was used to examine the voids. Twin-jet electropolished specimens were prepared for precipitate, micro-grain and substructure analyses using Transmission Kikuchi Diffraction (TKD) combined with Energy Dispersive Spectrometry (EDS), Concentric Backscatter (CBS) imaging, Energy-Filtered Transmission Electron Microscopy (EFTEM), and Annular Dark-Field Scanning Transmission Electron Microscopy (ADF-STEM) combined with EDS. The precipitates were extracted from the iron matrix using Bulk Replication and further investigated using EFTEM and STEM-EDS.
- Full Text:
- Date Issued: 2019
- Authors: Marx, Genevéve
- Date: 2019
- Subjects: Stainless steel -- Welding
- Language: English
- Type: Thesis , Doctoral , DPhil
- Identifier: http://hdl.handle.net/10948/30766 , vital:31128
- Description: Tempered martensite ferritic (TMF) steels with 9-12% Cr additions are used extensively for high-pressure steam pipes in coal-fired power plants. They operate at temperatures above 500ºC and are consequently susceptible to creep damage. Due to economic reasons, welding must be performed on service exposed materials when a component needs to be replaced. Fusion welding results in the formation of different microstructural regions within the weldment. The primary failure mechanism of TMF steel welded components is Type IV cracking that results from accelerated void formation in the fine-grained heat affected zone (FGHAZ) during creep. Short-term creep-tests performed across weldments made on new and service exposed steels have shown that the weldment consistently fails in the FGHAZ of the service exposed material. This observation has not yet been fully explained since not much is known about the microstructural evolution of creep aged material during welding. Thus, further investigation on the microstructure of welded creep aged material is warranted. The main aim of this thesis was to investigate the microstructural evolution when welding upon creep aged 9-12% Cr martensitic steels using advanced electron microscopy techniques. X20CrMoV12-1 (12% Cr) in the virgin and long-term service-exposed state were investigated. GleebleTM weld simulation of the FGHAZ was performed on the materials. Detailed microstructural investigations were conducted on the parent and simulated FGHAZ materials to analyse the voids, dislocation density, micro-grains, and precipitates (M23C6, MX, Laves, Z-phase) in the materials. Light Microscopy (LM) and Scanning Electron Microscopy (SEM) was used to examine the voids. Twin-jet electropolished specimens were prepared for precipitate, micro-grain and substructure analyses using Transmission Kikuchi Diffraction (TKD) combined with Energy Dispersive Spectrometry (EDS), Concentric Backscatter (CBS) imaging, Energy-Filtered Transmission Electron Microscopy (EFTEM), and Annular Dark-Field Scanning Transmission Electron Microscopy (ADF-STEM) combined with EDS. The precipitates were extracted from the iron matrix using Bulk Replication and further investigated using EFTEM and STEM-EDS.
- Full Text:
- Date Issued: 2019
Optimising construction project role-player performance
- Authors: Hefer, Andre Le Roux
- Date: 2019
- Subjects: Construction industry -- Management , Project management Performance
- Language: English
- Type: Thesis , Doctoral , DPhil
- Identifier: http://hdl.handle.net/10948/40316 , vital:36140
- Description: Authors predict major changes in the requirements to manage complex environments in the 21st century. These 21st century challenges, for Project Managers (PM) in the construction industry, are evident through the ongoing perception that the industry performance record is suboptimal. In the pursuit of performance optimisation, management disciplines developed and implemented theories and models not only to achieve what is required, but also to excel and create high-performing teams. In search of project success, researchers have also identified quantifiable variables, models, success factors and other related issues. The PM’s role in the attainment of success has also been widely researched, especially the impact, influence, methods and tools related to the discipline. Nevertheless, the general concern remains, that the performance of the industry is suboptimal. This study therefore aimed to qualitatively evaluate and examine the various factors and influences on performance of a construction project team. This research applies to the motivation and environmental factors influencing project teams in the achievement of optimum performance; and in doing so, to enhance the performance of project-role players; while adding disciplinespecific theory. This study has employed in-depth interview data, which were thematically analysed. The interviews were conducted in a case-study design comprising four projects in South Africa. The study concluded by emphasising the importance of how role-players RELATE to each other, and LOVE project challenges. It further noted that PMs who are MANAGING LEADERS would be most influential in the project environment; while PROCUREMENT greatly influences the project environment. Relational issues are important to role-players; and they act as MOTIVATORS, with certain issues in a project presenting both performance BARRIERS and DRIVER capabilities. Finally, project MOMENTUM changes constantly, with the current momentum direction influencing the future course thereof. In meeting the aims of the research, a Performance Optimisation Framework was developed, noting how the emergent themes co-exist in optimal performance environments. The study also developed the Project Husbandry approach, reflecting on a caring, nurturing, diligent and mature approach when managing role-players. The study recommends that the themes impacting the project-operating environment should be influenced by management and leadership, in order to optimise the performance of all the role-players involved.
- Full Text:
- Date Issued: 2019
- Authors: Hefer, Andre Le Roux
- Date: 2019
- Subjects: Construction industry -- Management , Project management Performance
- Language: English
- Type: Thesis , Doctoral , DPhil
- Identifier: http://hdl.handle.net/10948/40316 , vital:36140
- Description: Authors predict major changes in the requirements to manage complex environments in the 21st century. These 21st century challenges, for Project Managers (PM) in the construction industry, are evident through the ongoing perception that the industry performance record is suboptimal. In the pursuit of performance optimisation, management disciplines developed and implemented theories and models not only to achieve what is required, but also to excel and create high-performing teams. In search of project success, researchers have also identified quantifiable variables, models, success factors and other related issues. The PM’s role in the attainment of success has also been widely researched, especially the impact, influence, methods and tools related to the discipline. Nevertheless, the general concern remains, that the performance of the industry is suboptimal. This study therefore aimed to qualitatively evaluate and examine the various factors and influences on performance of a construction project team. This research applies to the motivation and environmental factors influencing project teams in the achievement of optimum performance; and in doing so, to enhance the performance of project-role players; while adding disciplinespecific theory. This study has employed in-depth interview data, which were thematically analysed. The interviews were conducted in a case-study design comprising four projects in South Africa. The study concluded by emphasising the importance of how role-players RELATE to each other, and LOVE project challenges. It further noted that PMs who are MANAGING LEADERS would be most influential in the project environment; while PROCUREMENT greatly influences the project environment. Relational issues are important to role-players; and they act as MOTIVATORS, with certain issues in a project presenting both performance BARRIERS and DRIVER capabilities. Finally, project MOMENTUM changes constantly, with the current momentum direction influencing the future course thereof. In meeting the aims of the research, a Performance Optimisation Framework was developed, noting how the emergent themes co-exist in optimal performance environments. The study also developed the Project Husbandry approach, reflecting on a caring, nurturing, diligent and mature approach when managing role-players. The study recommends that the themes impacting the project-operating environment should be influenced by management and leadership, in order to optimise the performance of all the role-players involved.
- Full Text:
- Date Issued: 2019
Oral narratives as intertexts in selected Nigerian films
- Authors: Usman, Joshua
- Date: 2019
- Subjects: Folk literature -- Nigeria , Oral tradition -- Nigeria Motion pictures -- Nigeria
- Language: English
- Type: Thesis , Doctoral , DPhil
- Identifier: http://hdl.handle.net/10948/43721 , vital:37038
- Description: This research into the interface between orality and Nigerian film builds on previous scholarly works in the field (Ladebo (1992), Onabajo and M’Bayo (2009), Omolola (2013), Ezeigbo (2013), Mgbemere (2015) and Onzuike (2016)). Evident from these studies is the prevalence of recurring patterns of oral narratives in Nigerian film. The aim of this study is to consider the following research questions: Do film producers/directors adopt the use of oral narratives in Nigerian film texts? How do oral narratives translate into films? What is the rate of recurrence of oral narratives in Nigerian films? Do oral narratives aesthetically influence the quality of Nigerian films? For the purpose of this study a selection of nine Nigerian films (three each from the Yoruba, Hausa and Igbo groups). These films are analysed as primary texts to show the occurrence of elements of orature and oral narratives. Underpinning such analysis is the theory of intertextuality as coined by the French linguist Julia Kristeva. Kristeva sees the text as “intertextuality […] within the text of society and history” (Kristeva, 1980: 37). This approach is augmented by the views of Greenblatt on New Historicism, which implies literature should be studied and interpreted within the context of the history of the author and cultural/social context. The nine films under discussion are considered within their cultural/social context.
- Full Text:
- Date Issued: 2019
- Authors: Usman, Joshua
- Date: 2019
- Subjects: Folk literature -- Nigeria , Oral tradition -- Nigeria Motion pictures -- Nigeria
- Language: English
- Type: Thesis , Doctoral , DPhil
- Identifier: http://hdl.handle.net/10948/43721 , vital:37038
- Description: This research into the interface between orality and Nigerian film builds on previous scholarly works in the field (Ladebo (1992), Onabajo and M’Bayo (2009), Omolola (2013), Ezeigbo (2013), Mgbemere (2015) and Onzuike (2016)). Evident from these studies is the prevalence of recurring patterns of oral narratives in Nigerian film. The aim of this study is to consider the following research questions: Do film producers/directors adopt the use of oral narratives in Nigerian film texts? How do oral narratives translate into films? What is the rate of recurrence of oral narratives in Nigerian films? Do oral narratives aesthetically influence the quality of Nigerian films? For the purpose of this study a selection of nine Nigerian films (three each from the Yoruba, Hausa and Igbo groups). These films are analysed as primary texts to show the occurrence of elements of orature and oral narratives. Underpinning such analysis is the theory of intertextuality as coined by the French linguist Julia Kristeva. Kristeva sees the text as “intertextuality […] within the text of society and history” (Kristeva, 1980: 37). This approach is augmented by the views of Greenblatt on New Historicism, which implies literature should be studied and interpreted within the context of the history of the author and cultural/social context. The nine films under discussion are considered within their cultural/social context.
- Full Text:
- Date Issued: 2019
Political education as a determinant of university students’ political participation in the Eastern Cape, South Africa
- Authors: Badaru, Kazeem Ajasa
- Date: 2019
- Subjects: Citizenship -- Study and teaching -- South Africa Democracy and education -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Doctoral , DPhil
- Identifier: http://hdl.handle.net/10353/15793 , vital:40524
- Description: Globally, there is a downward trend in youths’ political interest and participation in the learning of political education in their school curricula as a measure to combat the apparent dangers posed by the declining young citizens’ participation in the political processes.This study therefore investigated political education as a determinant of university students’ political participation in the Province of the Eastern Cape, South Africa. The study employed a mixed methods design. Using the probability sampling technique, a sample of 375 participants was randomly selected from one university in the Eastern Cape Province while semi-structured interviews were conducted among five (5) purposively selected members of the same university’s Student Representative Council (SRC) executive committee. Simple descriptive statistics such as frequency counts and percentages were used to summarize all categories of variables; while Pearson correlation statistics, Chi-square and Ordinary least square regression were used to examine the relationship between dependent and independent variables at a 95percent confidence interval. Alpha values less than 0.05 were considered to be statistically significant. Thematic content analysis was performed on the qualitative data. The quantitative analysis revealed that students’ level of political awareness was high; 98.1percent of them were aware of their rights to vote and be voted for. Students’ political judgment was positively correlated with participation in campus (r =0.182) and national politics (r = 0.030) respectively. Most of the students agreed to take part in the 2018 SRC (78.8percent) and 2019 national elections (77.9percent) respectively. Political interest was significantly correlated with participation in campus (r = 0.375) and national politics (r =0. 404). The findings from the multivariate analysis showed that political interest (<0.001), parents’ political involvement (<0.001) and year of study (<0.001) were the significant determinants of students’ participation in politics. The qualitative findings also showed that there was a positive relationship between political education and students’ participation in politics. Since political interest and family are element and agent of political education respectively, it is concluded that political education is to a large extent a determinant of university students’ political participation. It is recommended that the universities, the Department of Higher Education and Training (DHET) and other stakeholders should do a thorough review of the university education curricula and programmes to ensure that political education is adequately accommodated and taken care of in a way that would increase students’ interest, awareness and participation in politics. When this is amply done, students’ cognitive skills and capacities would be enhanced to increase their participation in the political processes in South Africa.
- Full Text:
- Date Issued: 2019
- Authors: Badaru, Kazeem Ajasa
- Date: 2019
- Subjects: Citizenship -- Study and teaching -- South Africa Democracy and education -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Doctoral , DPhil
- Identifier: http://hdl.handle.net/10353/15793 , vital:40524
- Description: Globally, there is a downward trend in youths’ political interest and participation in the learning of political education in their school curricula as a measure to combat the apparent dangers posed by the declining young citizens’ participation in the political processes.This study therefore investigated political education as a determinant of university students’ political participation in the Province of the Eastern Cape, South Africa. The study employed a mixed methods design. Using the probability sampling technique, a sample of 375 participants was randomly selected from one university in the Eastern Cape Province while semi-structured interviews were conducted among five (5) purposively selected members of the same university’s Student Representative Council (SRC) executive committee. Simple descriptive statistics such as frequency counts and percentages were used to summarize all categories of variables; while Pearson correlation statistics, Chi-square and Ordinary least square regression were used to examine the relationship between dependent and independent variables at a 95percent confidence interval. Alpha values less than 0.05 were considered to be statistically significant. Thematic content analysis was performed on the qualitative data. The quantitative analysis revealed that students’ level of political awareness was high; 98.1percent of them were aware of their rights to vote and be voted for. Students’ political judgment was positively correlated with participation in campus (r =0.182) and national politics (r = 0.030) respectively. Most of the students agreed to take part in the 2018 SRC (78.8percent) and 2019 national elections (77.9percent) respectively. Political interest was significantly correlated with participation in campus (r = 0.375) and national politics (r =0. 404). The findings from the multivariate analysis showed that political interest (<0.001), parents’ political involvement (<0.001) and year of study (<0.001) were the significant determinants of students’ participation in politics. The qualitative findings also showed that there was a positive relationship between political education and students’ participation in politics. Since political interest and family are element and agent of political education respectively, it is concluded that political education is to a large extent a determinant of university students’ political participation. It is recommended that the universities, the Department of Higher Education and Training (DHET) and other stakeholders should do a thorough review of the university education curricula and programmes to ensure that political education is adequately accommodated and taken care of in a way that would increase students’ interest, awareness and participation in politics. When this is amply done, students’ cognitive skills and capacities would be enhanced to increase their participation in the political processes in South Africa.
- Full Text:
- Date Issued: 2019
Pre-service education students’ application of visualisation strategies to solve mathematical word-problems
- Authors: Shaw, Peter
- Date: 2019
- Subjects: Word problems (Mathematics)
- Language: English
- Type: Thesis , Doctoral , DPhil
- Identifier: http://hdl.handle.net/10353/16604 , vital:40735
- Description: This classroom-based action research dissertation examined visualisation strategies used by pre-service Intermediate Phase PGCE education students to solve mathematical word-problems. The setting was an Eastern Cape university. Previous literature indicated a positive correlation between the use of visual scaffolds and success in solving word problems. However, a gap was found insofar as little research had been published on the application of visualisation to word-problems by student teachers in South Africa. This thesis advances our understanding of the role visualisation may play in assisting student teachers to solve word-problems. The theoretic framework was informed by Bruner’s theory of learning. The research was grounded in the hermeneutic tradition. An interpretivist research paradigm was expedited by using an inductive, naturalistic perspective and relativist ontology. Thirty-eight student-teachers participated in the study. Parallel and convergent qualitative and quantitative data gathering instruments were used, thereby facilitating triangulation and examination for microgenesis. It was found that vestiges of past teaching practices initially limited the participants’ knowledge to a deeply-flawed, banking model of routines and an instrumental perception of mathematics. Disruptive calls for social justice impeded progress. Albeit visualisation strategies liberated understanding, many foundational concepts and skills had to be reconstructed. The confluence of time and rehearsal culminated in some measure of expertise. Sustained effort enabled new knowledge to be compressed and consigned to long-term memory. Salient visual representations assisted participants to conceptualise relational mathematical meta-concepts and reduced the cognitive demands imposed by word-problems but that achievement was a hard-won prize.
- Full Text:
- Date Issued: 2019
- Authors: Shaw, Peter
- Date: 2019
- Subjects: Word problems (Mathematics)
- Language: English
- Type: Thesis , Doctoral , DPhil
- Identifier: http://hdl.handle.net/10353/16604 , vital:40735
- Description: This classroom-based action research dissertation examined visualisation strategies used by pre-service Intermediate Phase PGCE education students to solve mathematical word-problems. The setting was an Eastern Cape university. Previous literature indicated a positive correlation between the use of visual scaffolds and success in solving word problems. However, a gap was found insofar as little research had been published on the application of visualisation to word-problems by student teachers in South Africa. This thesis advances our understanding of the role visualisation may play in assisting student teachers to solve word-problems. The theoretic framework was informed by Bruner’s theory of learning. The research was grounded in the hermeneutic tradition. An interpretivist research paradigm was expedited by using an inductive, naturalistic perspective and relativist ontology. Thirty-eight student-teachers participated in the study. Parallel and convergent qualitative and quantitative data gathering instruments were used, thereby facilitating triangulation and examination for microgenesis. It was found that vestiges of past teaching practices initially limited the participants’ knowledge to a deeply-flawed, banking model of routines and an instrumental perception of mathematics. Disruptive calls for social justice impeded progress. Albeit visualisation strategies liberated understanding, many foundational concepts and skills had to be reconstructed. The confluence of time and rehearsal culminated in some measure of expertise. Sustained effort enabled new knowledge to be compressed and consigned to long-term memory. Salient visual representations assisted participants to conceptualise relational mathematical meta-concepts and reduced the cognitive demands imposed by word-problems but that achievement was a hard-won prize.
- Full Text:
- Date Issued: 2019
Selected stakeholders’ views on the use of tablet computers in learning and teaching – a South African case study at a university
- Fernandez, Simon Christopher
- Authors: Fernandez, Simon Christopher
- Date: 2019
- Subjects: Computer-assisted instruction Tablet computers Educational technology
- Language: English
- Type: Thesis , Doctoral , DPhil
- Identifier: http://hdl.handle.net/10353/15903 , vital:40553
- Description: The popularity of mobile technologies has greatly influenced the people of all ages, especially adolescents. Tablet computers as part of mobile technologies, were launched in colleges and universities in many countries to supplement and complement learning and teaching. However, research reports based on the effectiveness of the use of tablet computers in higher education institutions in South Africa’s Eastern Cape Province are scarce. In order to address the deficiency, this study examined the views of stakeholders such as students, lecturers and managers on the use of tablet computers for learning and teaching in one of the Eastern Cape universities. The research adopted the Post-Positivist paradigm and mixed method approach. The theoretical frameworks were Constructivism and Technological Pedagogical Content Knowledge. The sample consisted of (a) 155 students from a population of 254 extended-stream National Diploma students in Information and Communication Technology and National Diploma Electrical Engineering cohorts; (b) 14 lecturers from a relevant population of 25; and, (c) 16 managers from a population of 20. Three separate questionnaires as well as interview protocols for each of the stakeholder cohorts provided the core data. All members in the sample were surveyed. The researcher opted to be an outsider and received assistance from a few qualified trained academics to administer the questionnaire to students in different cohorts in order to minimise data bias. Only 18 students, five lecturers and nine managers were interviewed. Quantitative data were captured manually into Statistical Package for Social Sciences (version 24) and they were analysed using descriptive and inferential analysis: Analysis of Variance and Independent Samples t-test. Qualitative data were transcribed and analysed using thematic analysis to generate major themes and sub themes for the sub-research questions. Main strengths of using tablets from the findings of the study were (a) tablets motivated students in learning and lecturers in teaching (b) students understood the different styles of learning (c) enhanced students’ engagement and collaboration in learning. Main weakness of using tablets were students’ use of tablets for personal work and social networking during class hours was causing distractions to lecturers and other students. Generally, the evidence shows that strengths were greater than the weaknesses. It should also be noted that all stakeholders were positive and not statistically significantly different from each other in their views towards the use of tablets for learning and teaching in university classroom. However, students had views different from lecturers on the advantages and disadvantages of using tablets. The variance could be due to new students or new lecturers’ ignorance in the effective use of tablets and this might change as their familiarity in the use of the device improves. The research report makes a few recommendations which include training to all students and lecturers on the effective use of tablet computers for learning and teaching and installation of relevant applications before the commencement of each academic year. Moreover, the Information and communication technology technical staff must prevent students from visiting unwanted and restricted sites by keeping a network based tracker and blocker software application.
- Full Text:
- Date Issued: 2019
- Authors: Fernandez, Simon Christopher
- Date: 2019
- Subjects: Computer-assisted instruction Tablet computers Educational technology
- Language: English
- Type: Thesis , Doctoral , DPhil
- Identifier: http://hdl.handle.net/10353/15903 , vital:40553
- Description: The popularity of mobile technologies has greatly influenced the people of all ages, especially adolescents. Tablet computers as part of mobile technologies, were launched in colleges and universities in many countries to supplement and complement learning and teaching. However, research reports based on the effectiveness of the use of tablet computers in higher education institutions in South Africa’s Eastern Cape Province are scarce. In order to address the deficiency, this study examined the views of stakeholders such as students, lecturers and managers on the use of tablet computers for learning and teaching in one of the Eastern Cape universities. The research adopted the Post-Positivist paradigm and mixed method approach. The theoretical frameworks were Constructivism and Technological Pedagogical Content Knowledge. The sample consisted of (a) 155 students from a population of 254 extended-stream National Diploma students in Information and Communication Technology and National Diploma Electrical Engineering cohorts; (b) 14 lecturers from a relevant population of 25; and, (c) 16 managers from a population of 20. Three separate questionnaires as well as interview protocols for each of the stakeholder cohorts provided the core data. All members in the sample were surveyed. The researcher opted to be an outsider and received assistance from a few qualified trained academics to administer the questionnaire to students in different cohorts in order to minimise data bias. Only 18 students, five lecturers and nine managers were interviewed. Quantitative data were captured manually into Statistical Package for Social Sciences (version 24) and they were analysed using descriptive and inferential analysis: Analysis of Variance and Independent Samples t-test. Qualitative data were transcribed and analysed using thematic analysis to generate major themes and sub themes for the sub-research questions. Main strengths of using tablets from the findings of the study were (a) tablets motivated students in learning and lecturers in teaching (b) students understood the different styles of learning (c) enhanced students’ engagement and collaboration in learning. Main weakness of using tablets were students’ use of tablets for personal work and social networking during class hours was causing distractions to lecturers and other students. Generally, the evidence shows that strengths were greater than the weaknesses. It should also be noted that all stakeholders were positive and not statistically significantly different from each other in their views towards the use of tablets for learning and teaching in university classroom. However, students had views different from lecturers on the advantages and disadvantages of using tablets. The variance could be due to new students or new lecturers’ ignorance in the effective use of tablets and this might change as their familiarity in the use of the device improves. The research report makes a few recommendations which include training to all students and lecturers on the effective use of tablet computers for learning and teaching and installation of relevant applications before the commencement of each academic year. Moreover, the Information and communication technology technical staff must prevent students from visiting unwanted and restricted sites by keeping a network based tracker and blocker software application.
- Full Text:
- Date Issued: 2019
Study habits and learning styles as correlates of grade 11 students’ academic performance in mathematical literacy in the Amathole Education District
- Authors: Yako, Mzwandile John-Mott
- Date: 2019
- Subjects: Academic performance
- Language: English
- Type: Thesis , Doctoral , DPhil
- Identifier: http://hdl.handle.net/10353/16687 , vital:40743
- Description: This study investigated whether there was correlation in study habits and learning styles with Mathematical Literacy among the Grade 11 (eleven) high school learners. The Amatole Education District was chosen for this study since it is composed of urban and rural schools. Since Mathematical Literacy was introduced in the system of education in South Africa with the understanding that learners who are finding it a challenge to study Mathematics be complemented with Mathematical Literacy to provide them with skills that are a prerequisite for tertiary level and participation in the economic development. The study purposed to establish whether there was a relationship between academic performance with study habits and learning styles in Mathematical Literacy. The study used the post-positivistic paradigm; the approach was quantitative and the design was descriptive correlational. In sampling probability, cluster sampling was used based on the number of high schools in the Amatole Education District of the Eastern Cape. It was then followed by sub-sampling of learners in Grade 11 (eleven) whose mathematical Literacy skills and performance were being investigated in this study. The theory of Covey on study habits and Kolb’s theory on learning styles were used as a theoretical framework for the study. The data collection instrument used was a closed-ended questionnaire based on a Likert scale measurement. Confidentiality and anonymity were emphasized with informed consent in place. Data was analyzed using SPSS software and Microsoft Excel. The results showed a significant relationship between note taking, writing skills and Mathematical Literacy skills and performance. The findings on the learning styles indicated no significant relationship between socio-demographic factors (visual language, visual numerical, auditory-numerical e.tc.) and academic performance in Mathematical Literacy. This research revealed that study habits had an impact on the academic performance of learners in mathematical literacy. This relationship between academic performance and study habits is an indication that learners needed to improve in their use of English as a second language, especially on note taking, writing skills and Mathematical Literacy.
- Full Text:
- Date Issued: 2019
- Authors: Yako, Mzwandile John-Mott
- Date: 2019
- Subjects: Academic performance
- Language: English
- Type: Thesis , Doctoral , DPhil
- Identifier: http://hdl.handle.net/10353/16687 , vital:40743
- Description: This study investigated whether there was correlation in study habits and learning styles with Mathematical Literacy among the Grade 11 (eleven) high school learners. The Amatole Education District was chosen for this study since it is composed of urban and rural schools. Since Mathematical Literacy was introduced in the system of education in South Africa with the understanding that learners who are finding it a challenge to study Mathematics be complemented with Mathematical Literacy to provide them with skills that are a prerequisite for tertiary level and participation in the economic development. The study purposed to establish whether there was a relationship between academic performance with study habits and learning styles in Mathematical Literacy. The study used the post-positivistic paradigm; the approach was quantitative and the design was descriptive correlational. In sampling probability, cluster sampling was used based on the number of high schools in the Amatole Education District of the Eastern Cape. It was then followed by sub-sampling of learners in Grade 11 (eleven) whose mathematical Literacy skills and performance were being investigated in this study. The theory of Covey on study habits and Kolb’s theory on learning styles were used as a theoretical framework for the study. The data collection instrument used was a closed-ended questionnaire based on a Likert scale measurement. Confidentiality and anonymity were emphasized with informed consent in place. Data was analyzed using SPSS software and Microsoft Excel. The results showed a significant relationship between note taking, writing skills and Mathematical Literacy skills and performance. The findings on the learning styles indicated no significant relationship between socio-demographic factors (visual language, visual numerical, auditory-numerical e.tc.) and academic performance in Mathematical Literacy. This research revealed that study habits had an impact on the academic performance of learners in mathematical literacy. This relationship between academic performance and study habits is an indication that learners needed to improve in their use of English as a second language, especially on note taking, writing skills and Mathematical Literacy.
- Full Text:
- Date Issued: 2019
Sustainable rural development through community participation: modeling community-based tourism in Nqileni village, Eastern Cape, South Africa
- Authors: Setokoe, Tshepiso Jonathan
- Date: 2019
- Subjects: Rural development -- South Africa -- Eastern Cape , Tourism -- South Africa Tourism -- South Africa -- Eastern Cape Ecotourism
- Language: English
- Type: Thesis , Doctoral , DPhil
- Identifier: http://hdl.handle.net/10948/43379 , vital:36863
- Description: The development of tourism has been heralded to be a mechanism for sustainable rural development. Sustainable development of any nature requires that any efforts aimed at developing rural areas must involve the community in which the development is undertaken. This has given rise to concerted efforts by governments and development practitioners to involve local communities in development initiatives undertaken within their locale. The study analysed the importance of community participation in tourism development, with the aim to ensure the sustainable rural development of areas such as Nqileni village. This was undertaken using a qualitative research approach using semi-structured interviews to solicit data from twenty members of the Nqileni village community. The data was analysed with the assistance of a specialist qualitative data analyst, using the NVivo sytem, version 11, and was objectively interpreted and analysed by the researcher. The results revealed that the community viewed their participation to be paramount in development initiatives undertaken within the area, which also allows for the building of capacity, and ultimately empowers the community to meaningfully participate in the sustainable development of the area. Finally, the study proposed a community-based tourism model for sustainable rural development, which placed community participations at the root of sustainable development. This has been presented in a form that proposes that a leadership that works together in harmony, coupled with a flow of tourists and investment in the area, which can encourage the community to participate in tourism, resulting in a tourism economy that will allow for positive impacts (such as employment, conservation of resources and preservation of culture).This will enable the reduction of poverty, revival of other economic sectors within the area and foster social cohesion, and ultimately developing the area and its people.
- Full Text:
- Date Issued: 2019
- Authors: Setokoe, Tshepiso Jonathan
- Date: 2019
- Subjects: Rural development -- South Africa -- Eastern Cape , Tourism -- South Africa Tourism -- South Africa -- Eastern Cape Ecotourism
- Language: English
- Type: Thesis , Doctoral , DPhil
- Identifier: http://hdl.handle.net/10948/43379 , vital:36863
- Description: The development of tourism has been heralded to be a mechanism for sustainable rural development. Sustainable development of any nature requires that any efforts aimed at developing rural areas must involve the community in which the development is undertaken. This has given rise to concerted efforts by governments and development practitioners to involve local communities in development initiatives undertaken within their locale. The study analysed the importance of community participation in tourism development, with the aim to ensure the sustainable rural development of areas such as Nqileni village. This was undertaken using a qualitative research approach using semi-structured interviews to solicit data from twenty members of the Nqileni village community. The data was analysed with the assistance of a specialist qualitative data analyst, using the NVivo sytem, version 11, and was objectively interpreted and analysed by the researcher. The results revealed that the community viewed their participation to be paramount in development initiatives undertaken within the area, which also allows for the building of capacity, and ultimately empowers the community to meaningfully participate in the sustainable development of the area. Finally, the study proposed a community-based tourism model for sustainable rural development, which placed community participations at the root of sustainable development. This has been presented in a form that proposes that a leadership that works together in harmony, coupled with a flow of tourists and investment in the area, which can encourage the community to participate in tourism, resulting in a tourism economy that will allow for positive impacts (such as employment, conservation of resources and preservation of culture).This will enable the reduction of poverty, revival of other economic sectors within the area and foster social cohesion, and ultimately developing the area and its people.
- Full Text:
- Date Issued: 2019
The anti-proliferative activity of drimia altissima and a novel isolated flavonoid glycoside against hela cervical cancer cells
- Authors: Nyambe, Mutenta Nsokolo
- Date: 2019
- Subjects: Cancer -- Research , Cervix uteri -- Cancer , Cervix uteri -- Cancer -- Diagnosis -- Developing countries
- Language: English
- Type: Thesis , Doctoral , DPhil
- Identifier: http://hdl.handle.net/10948/42770 , vital:36690
- Description: Cancer is one of the leading causes of mortality worldwide. About 44% of all cancer morbidity and 53% of all cancer mortality occur in countries with a low to medium Human Development Index (HDI). Thus, cancer is rapidly emerging as a serious threat to public health in Africa and most especially, sub-Saharan Africa. The International Agency for Research on Cancer (IARC) projects that there will be 1.28 million new cancer cases and 970 000 cancer deaths in Africa by the year 2030 owing to the increase in economic development associated lifestyles. The dominant types of cancer in Africa are those related to infectious diseases such as Kaposi’s sarcoma and cervical, hepatic and urinary bladder carcinomas. The main challenge to cancer treatment in Africa is the unavailability of efficacious anticancer drugs. This is because most developing countries can only afford to procure the most basic anticancer drugs, which are also frequently unavailable due to intermittent supplies. This results in patients progressing to more advanced cancer states. One way of combating this African problem is to focus on research that aims at discovering efficacious and cost effective cancer therapies from available natural resources within the African continent. This study investigated the potential anti-proliferative activity (against HeLa cervical cancer cells) of four plants (Adansonia digitata, Ceiba pentandra, Maytenus senegalensis and Drimia altissima) commonly used in the African traditional treatment of malignancies. After in vitro bio-assay screening using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assay, M. senegalensis root extract (MS-R) and D. altissima bulb extract (DA-B) showed anti-proliferative activity against HeLa cervical cancer cells with IC50 values of 25 μg/mL and 1.1 μg/mL respectively. By possessing the strongest anti-proliferative activity among the tested extracts, D. altissima was selected for further studies. Liquid-liquid partitioning of the Drimia altissima bulb extract with n-hexane, ethyl acetate, and n-butanol, yielded partitions 79a – d, with the n-butanol fraction, 79d, exhibiting the strongest cytotoxic activity (IC50 = 0.497 μg/mL). Through High Content Analysis (HCA) screening, fraction 79d was found to induce marked early mitotic cell cycle arrest. Fractionation of 79d using Diaion® HP-20 open column chromatography and a stepwise gradient of reducing polarity (water-methanol-ethanol-ethyl acetate) yielded cytotoxic fractions 82b, 82c, 82d and 82e, all with significant anti-proliferative activities at the tested concentrations of 0.1, 1.0 and 10 μg/mL. Bio-assay guided fractionation of 82c (the most effective fraction at the lowest tested concentration of 0.1 μg/mL) using Sephadex® LH-20 open column chromatography and 50% MeOH led to the isolation of compound 3.17. After structural elucidation using 1D and 2D Nuclear Magnetic Resonance spectroscopy (NMR), High resolution Mass spectrometry (HRMS), Fourier-Transform Infrared spectroscopy (FT-IR), ultraviolet spectroscopy (UV) and Circular Dichroism (CD), compound 3.17 was identified as a novel C-glucosylflavonoid-O-glucoside, 6-C-[-apio-α-D-furanosyl-(1→6)-β-glucopyranosyl]-4′, 5, 7-trihydroxyflavone (Altissimin, 3.17). Compound 3.17 exhibited a dose dependant anti-proliferative activity with an IC50 of 2.44 μM. The mechanism of action for compound 3.17 was investigated through cell cycle arrest, phosphatidylserine translocation (PS), caspase activation and mitochondrial membrane depolarization. The mechanism of cell death elicited by compound 3.17 in HeLa cells was found to involve the induction of M phase cell cycle arrest with consequent activation of apoptotic cell death which was evident from annexin V staining, mitochondrial membrane potential (ΔΨm) collapse and the activation of caspases -8 and -3. In silico computational techniques were employed to virtually determine potential biological targets of compound 3.17. Target fishing using the Similarity Ensemble Approach (SEA) target prediction gave human aldose reductase (hAR, AKR1B1) the highest ranking with a p value of 2.85 x 10-24, a max Tc of 0.35 and a Z-score of 41.8217. Using AutoDock4 and the AutoDock tools suite (ADT), molecular docking of compound 3.17 in the hAR binding pocket was successfully achieved with a lower ΔG free energy binding (-9.4 kcal/mol) than that of positive control ligand 393 (-8.7 kcal/mol). In conclusion, this study identified the genus Drimia and particularly D. altissima as a potential source for novel cytotoxic compounds. The discovery of altissimin (3.17), the first flavonoid glycoside to be isolate from D. altissima, enquires into the possible existence of similar compounds within the species. In addition to the observed in vitro cytotoxic activity against HeLa cells, the potential of altissimin (3.17) as a hAR enzyme inhibitor opens up the possibility of its use as an adjunct to increase cancer cell sensitivity to chemotherapy. Thus, altissimin (3.17) shows promise as a potential anticancer agent.
- Full Text:
- Date Issued: 2019
- Authors: Nyambe, Mutenta Nsokolo
- Date: 2019
- Subjects: Cancer -- Research , Cervix uteri -- Cancer , Cervix uteri -- Cancer -- Diagnosis -- Developing countries
- Language: English
- Type: Thesis , Doctoral , DPhil
- Identifier: http://hdl.handle.net/10948/42770 , vital:36690
- Description: Cancer is one of the leading causes of mortality worldwide. About 44% of all cancer morbidity and 53% of all cancer mortality occur in countries with a low to medium Human Development Index (HDI). Thus, cancer is rapidly emerging as a serious threat to public health in Africa and most especially, sub-Saharan Africa. The International Agency for Research on Cancer (IARC) projects that there will be 1.28 million new cancer cases and 970 000 cancer deaths in Africa by the year 2030 owing to the increase in economic development associated lifestyles. The dominant types of cancer in Africa are those related to infectious diseases such as Kaposi’s sarcoma and cervical, hepatic and urinary bladder carcinomas. The main challenge to cancer treatment in Africa is the unavailability of efficacious anticancer drugs. This is because most developing countries can only afford to procure the most basic anticancer drugs, which are also frequently unavailable due to intermittent supplies. This results in patients progressing to more advanced cancer states. One way of combating this African problem is to focus on research that aims at discovering efficacious and cost effective cancer therapies from available natural resources within the African continent. This study investigated the potential anti-proliferative activity (against HeLa cervical cancer cells) of four plants (Adansonia digitata, Ceiba pentandra, Maytenus senegalensis and Drimia altissima) commonly used in the African traditional treatment of malignancies. After in vitro bio-assay screening using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assay, M. senegalensis root extract (MS-R) and D. altissima bulb extract (DA-B) showed anti-proliferative activity against HeLa cervical cancer cells with IC50 values of 25 μg/mL and 1.1 μg/mL respectively. By possessing the strongest anti-proliferative activity among the tested extracts, D. altissima was selected for further studies. Liquid-liquid partitioning of the Drimia altissima bulb extract with n-hexane, ethyl acetate, and n-butanol, yielded partitions 79a – d, with the n-butanol fraction, 79d, exhibiting the strongest cytotoxic activity (IC50 = 0.497 μg/mL). Through High Content Analysis (HCA) screening, fraction 79d was found to induce marked early mitotic cell cycle arrest. Fractionation of 79d using Diaion® HP-20 open column chromatography and a stepwise gradient of reducing polarity (water-methanol-ethanol-ethyl acetate) yielded cytotoxic fractions 82b, 82c, 82d and 82e, all with significant anti-proliferative activities at the tested concentrations of 0.1, 1.0 and 10 μg/mL. Bio-assay guided fractionation of 82c (the most effective fraction at the lowest tested concentration of 0.1 μg/mL) using Sephadex® LH-20 open column chromatography and 50% MeOH led to the isolation of compound 3.17. After structural elucidation using 1D and 2D Nuclear Magnetic Resonance spectroscopy (NMR), High resolution Mass spectrometry (HRMS), Fourier-Transform Infrared spectroscopy (FT-IR), ultraviolet spectroscopy (UV) and Circular Dichroism (CD), compound 3.17 was identified as a novel C-glucosylflavonoid-O-glucoside, 6-C-[-apio-α-D-furanosyl-(1→6)-β-glucopyranosyl]-4′, 5, 7-trihydroxyflavone (Altissimin, 3.17). Compound 3.17 exhibited a dose dependant anti-proliferative activity with an IC50 of 2.44 μM. The mechanism of action for compound 3.17 was investigated through cell cycle arrest, phosphatidylserine translocation (PS), caspase activation and mitochondrial membrane depolarization. The mechanism of cell death elicited by compound 3.17 in HeLa cells was found to involve the induction of M phase cell cycle arrest with consequent activation of apoptotic cell death which was evident from annexin V staining, mitochondrial membrane potential (ΔΨm) collapse and the activation of caspases -8 and -3. In silico computational techniques were employed to virtually determine potential biological targets of compound 3.17. Target fishing using the Similarity Ensemble Approach (SEA) target prediction gave human aldose reductase (hAR, AKR1B1) the highest ranking with a p value of 2.85 x 10-24, a max Tc of 0.35 and a Z-score of 41.8217. Using AutoDock4 and the AutoDock tools suite (ADT), molecular docking of compound 3.17 in the hAR binding pocket was successfully achieved with a lower ΔG free energy binding (-9.4 kcal/mol) than that of positive control ligand 393 (-8.7 kcal/mol). In conclusion, this study identified the genus Drimia and particularly D. altissima as a potential source for novel cytotoxic compounds. The discovery of altissimin (3.17), the first flavonoid glycoside to be isolate from D. altissima, enquires into the possible existence of similar compounds within the species. In addition to the observed in vitro cytotoxic activity against HeLa cells, the potential of altissimin (3.17) as a hAR enzyme inhibitor opens up the possibility of its use as an adjunct to increase cancer cell sensitivity to chemotherapy. Thus, altissimin (3.17) shows promise as a potential anticancer agent.
- Full Text:
- Date Issued: 2019
The future of banking in South Africa towards 2055: disruptive innovation scenarios
- Authors: Koekemoer, Jonathan
- Date: 2019
- Subjects: Finance -- South Africa , Economic development -- South Africa , Banks and banking -- South Africa
- Language: English
- Type: Thesis , Doctoral , DPhil
- Identifier: http://hdl.handle.net/10948/40577 , vital:36184
- Description: The research effort developed four possible scenarios for the future of banking in South Africa towards 2055. The scenarios sought to stimulate thought on the possible, probable, plausible and preferred effects of disruptive innovation and regulation in the South African banking sector. The scenarios were developed in strict accordance with the 5 stages, and 9 steps, of the scenario-based planning process of futures studies. A conceptual futures studies model for banking in South Africa was developed to guide and clarify the way in which the research on South African banking can be integrated into the body of existing futures studies theory. The research study began with a comprehensive environmental scan, where various megatrends and driving forces are identified. A PESTEL analysis provided a deeper understanding of the driving forces. A Real-Time Delphi study was conducted in order to validate and prioritise the megatrends and driving forces that emerged. As a result, the research study was able to present four plausible scenarios that provide a better understanding of the future of banking in South Africa over the decades to come. The research presents banking as a complex, multi-faceted sector that is heavily influenced by advances in technology. The Real-Time Delphi research allowed the aggregation of expert knowledge. This is used as a guide to assist decision-makers and industry leaders in the adoption of appropriate business models and strategies towards a preferred future state. The research defined the Integrated Vision as the preferred future state for the South African banking sector towards 2055. The study closes a research gap where current strategies deviate from proposed strategies that drive the achievement of the Integrated Vision by 2055. Finally, contextually aligned practical recommendations are provided to assist decision-makers, industry leaders and change agents to work towards a preferable future state. The proposed recommendations are placed into broad categories of innovation, financial inclusion and collaborative regulatory relationships. The research makes a meaningful contribution to the South African banking sector by introducing a forward-looking, systems-thinking approach to disruptive innovation and regulation in the South African context.
- Full Text:
- Date Issued: 2019
- Authors: Koekemoer, Jonathan
- Date: 2019
- Subjects: Finance -- South Africa , Economic development -- South Africa , Banks and banking -- South Africa
- Language: English
- Type: Thesis , Doctoral , DPhil
- Identifier: http://hdl.handle.net/10948/40577 , vital:36184
- Description: The research effort developed four possible scenarios for the future of banking in South Africa towards 2055. The scenarios sought to stimulate thought on the possible, probable, plausible and preferred effects of disruptive innovation and regulation in the South African banking sector. The scenarios were developed in strict accordance with the 5 stages, and 9 steps, of the scenario-based planning process of futures studies. A conceptual futures studies model for banking in South Africa was developed to guide and clarify the way in which the research on South African banking can be integrated into the body of existing futures studies theory. The research study began with a comprehensive environmental scan, where various megatrends and driving forces are identified. A PESTEL analysis provided a deeper understanding of the driving forces. A Real-Time Delphi study was conducted in order to validate and prioritise the megatrends and driving forces that emerged. As a result, the research study was able to present four plausible scenarios that provide a better understanding of the future of banking in South Africa over the decades to come. The research presents banking as a complex, multi-faceted sector that is heavily influenced by advances in technology. The Real-Time Delphi research allowed the aggregation of expert knowledge. This is used as a guide to assist decision-makers and industry leaders in the adoption of appropriate business models and strategies towards a preferred future state. The research defined the Integrated Vision as the preferred future state for the South African banking sector towards 2055. The study closes a research gap where current strategies deviate from proposed strategies that drive the achievement of the Integrated Vision by 2055. Finally, contextually aligned practical recommendations are provided to assist decision-makers, industry leaders and change agents to work towards a preferable future state. The proposed recommendations are placed into broad categories of innovation, financial inclusion and collaborative regulatory relationships. The research makes a meaningful contribution to the South African banking sector by introducing a forward-looking, systems-thinking approach to disruptive innovation and regulation in the South African context.
- Full Text:
- Date Issued: 2019
The impact of public spending on economic growth, employment and poverty reduction in South Africa
- Authors: Kavese, Kambale
- Date: 2019
- Subjects: Expenditures, Public -- South Africa , Economic development -- South Africa Labor economics -- South Africa Employment (Economic theory) Poor -- Employment -- South Africa South Africa -- Economic conditions
- Language: English
- Type: Thesis , Doctoral , DPhil
- Identifier: http://hdl.handle.net/10948/39940 , vital:35570
- Description: This study seeks to assess the effect of public spending on economic growth, employment, and poverty reduction. The co-existence of a sound fiscal policy and a substantial government expenditure but insignificant returns in terms of social development suggests the potential of a dilemma that needs to be investigated, and to reflect on the dynamics of selected marginalised groups of people and marginalised areas. Hence, the “social inclusion” strategy of the RDP in 1994, and the “inclusive economy” strategy of the NDP in 2014 were implemented with one single objective in mind, that is to narrow the gaps associated with the legacy of apartheid. Despite the implantation of government plans like the RDP and recently the NDP, and regardless of the effective use of fiscal policy, low growth has continued during the post-recession era; unemployment and inequality have persistently remained at high levels. This paradox has led to controversies around fiscal policy’s dual role of stimulating economic growth and income redistribution. To achieve the research objective, the study employs four types of empirical techniques: the nonlinear autoregressive distributive lag (N-ARDL) cointegration model; the economy-wide Leontief approach calibrated on the supply and use tables (dynamic SUT model); a partial general equilibrium approach based on the Social Accounting Matrix (SAM model) used for micro-simulations; and lastly a contemporaneous dynamic computable general equilibrium (CGE) model to assess the effect of fiscal policy on macroeconomic and socioeconomic variables. The study found that during the post-recession era, expansionary fiscal policy had a positive but minute effect on growth, employment and poverty reduction. The effect of government spending has had a minimal effect on historically marginalised groups of people and marginalised areas. This is why a tortoise pace in reducing poverty and inequality has persisted. So, the study recommends that governments should follow a priorities-based government spending policy which fits well with the current situation of the country. Moreover, South Africa needs to adopt international standards and best practices of “science-based strategic” rather than that of “evidence-based strategy” and ensure that only programmes that have proved to be effective be financed in the fiscal budget.
- Full Text:
- Date Issued: 2019
- Authors: Kavese, Kambale
- Date: 2019
- Subjects: Expenditures, Public -- South Africa , Economic development -- South Africa Labor economics -- South Africa Employment (Economic theory) Poor -- Employment -- South Africa South Africa -- Economic conditions
- Language: English
- Type: Thesis , Doctoral , DPhil
- Identifier: http://hdl.handle.net/10948/39940 , vital:35570
- Description: This study seeks to assess the effect of public spending on economic growth, employment, and poverty reduction. The co-existence of a sound fiscal policy and a substantial government expenditure but insignificant returns in terms of social development suggests the potential of a dilemma that needs to be investigated, and to reflect on the dynamics of selected marginalised groups of people and marginalised areas. Hence, the “social inclusion” strategy of the RDP in 1994, and the “inclusive economy” strategy of the NDP in 2014 were implemented with one single objective in mind, that is to narrow the gaps associated with the legacy of apartheid. Despite the implantation of government plans like the RDP and recently the NDP, and regardless of the effective use of fiscal policy, low growth has continued during the post-recession era; unemployment and inequality have persistently remained at high levels. This paradox has led to controversies around fiscal policy’s dual role of stimulating economic growth and income redistribution. To achieve the research objective, the study employs four types of empirical techniques: the nonlinear autoregressive distributive lag (N-ARDL) cointegration model; the economy-wide Leontief approach calibrated on the supply and use tables (dynamic SUT model); a partial general equilibrium approach based on the Social Accounting Matrix (SAM model) used for micro-simulations; and lastly a contemporaneous dynamic computable general equilibrium (CGE) model to assess the effect of fiscal policy on macroeconomic and socioeconomic variables. The study found that during the post-recession era, expansionary fiscal policy had a positive but minute effect on growth, employment and poverty reduction. The effect of government spending has had a minimal effect on historically marginalised groups of people and marginalised areas. This is why a tortoise pace in reducing poverty and inequality has persisted. So, the study recommends that governments should follow a priorities-based government spending policy which fits well with the current situation of the country. Moreover, South Africa needs to adopt international standards and best practices of “science-based strategic” rather than that of “evidence-based strategy” and ensure that only programmes that have proved to be effective be financed in the fiscal budget.
- Full Text:
- Date Issued: 2019
The influence of multinational corporations in promoting foreign direct investment in the South African business environment
- Van der Berg, Jan Gabriel Mara
- Authors: Van der Berg, Jan Gabriel Mara
- Date: 2019
- Subjects: Investments, Foreign -- South Africa , Business enterprises Business Organisations Industrial promotion
- Language: English
- Type: Thesis , Doctoral , DPhil
- Identifier: http://hdl.handle.net/10948/44213 , vital:37131
- Description: One of the major driving forces behind international trade over the past thirty years has been Foreign Direct Investment (FDI). Due to the importance of FDI, a vast amount of research has been conducted on the various elements that make up FDI. There has also been widespread research done to measure the impact of FDI on host countries, and attempts have been made to determine the long-term benefits thereof. Despite the existent research on FDI, there is a dearth of literature on the unique situation in South Africa (due to the country’s fragmented past) and the impact of FDI on the South African economy. This study attempts to address this research gap and to add to the existent body of knowledge on FDI market entry. Thus, the primary objective of this study was to examine the impact of multinational corporations (MNCs) in promoting the entry of FDIs in South Africa, and the effectiveness of these investments in the South African business environment. The comprehensive literature review in this study included a discussion of the background to the pre- and post-apartheid South African economy, and the various efforts made by the South African government to facilitate sustainable economic growth through various economic policies. FDI was identified as one of the four major indicators of economic growth and was therefore investigated as a concept, strategy and driver of change. The South African marketing environment was analysed in order to assist in the identification of variables that are conducive to FDI. The final section of the literature review utilised three cases to better illustrate and understand the different challenges, market entry strategies and long-term implications of FDI. In this study, the independent variables (international marketing environment, stakeholder intervention, government considerations, resources and FDI incentives) were identified as influencing the mediating variable (FDI market entry strategy) and the dependent variables (competitiveness, sustainability, trade agreements and commitment of traders). These independent variables were selected to construct a hypothesised model and the research hypotheses. To this end, an empirical investigation was conducted, the measuring instrument used in this investigation was a questionnaire, which was assembled with the help of insights gained from secondary sources. The study respondents were selected through convenience sampling. A total of 210 respondents participated in the study, and 165 useable questionnaires were subjected to statistical analysis. The data collected for this study was subjected to five phases of analysis: exploratory factor analysis to assess validity; Cronbach’s alpha was used to test for internal consistency reliability; descriptive statistics to describe the fundamental features of the data by providing a statistical summary and analysis; and the nine hypotheses pertaining to the relationships between different variables were assessed using inferential statistical procedures, Pearson’s product correlation and regression analysis. This led to the adaptation of the hypothesised model and the hypotheses so as to indicate the changes resulting from the EFA. The findings of this study reveals that external stakeholder intervention as well as FDI incentives and resources effectively influence FDI market entry strategy in the South African business environment. The study results further reveal that the promotion of FDI market entry strategy positively influences competitiveness, sustainability, trade agreements and commitment of traders in the South African business environment. For MNCs to be successful in the expansion of FDI market entry strategy in the South African business environment, the study recommends that it is important to consider the availability of potential local partners, proximity to trading routes, reduction of the costs involved in supplying the market, the effect of tariff barriers and a competitive domestic economy. It is further recommended that MNCs need to focus on the utilisation of reliable and effective equipment in order to enable the productive management of operations in the South African business environment. The study also recommends the South African business environment as a strategic investment destination for the promotion of FDI market entry strategy as it offers low production costs in particular trading locations. This study has contributed to the field of FDI and the FDI market entry strategies employed by MNCs in South Africa. The research findings identified the international marketing (SLEPTS) factors through an assessment of the South African marketing environment, as these factors are deemed important for FDI to occur. The study also highlights the critical international marketing factors that could be used to improve local conditions through a mixture of incentives and policy re-alignment, so as to be more conducive to attracting large scale FDI. The hypothesised model developed for this study contributed to identifying the influence of external stakeholders on the successful market entry of FDI into South Africa, a critical element that MNCs usually only identify after market entry is complete. Evidence from the study shows that the South African government should direct FDI incentives towards those sectors in the economy that stand to benefit the most from the spill-over effects of FDI, in order to maximise the impact of FDI on the local economy. The research also indicates that elements such as restrictive legislation and government corruption may, to a certain degree, hinder FDI; therefore, these issues need to be addressed through legislation. It is recommended that all local efforts to attract FDI are industry or sector focussed, and that they are guided by government policies towards the greater benefit of the South African economy. Furthermore, the study found that the relationship between the host country and the MNC is critical to achieving sustainability in the long-term; therefore, it is suggested that the South African government improves its relationship with local businesses and MNCs that are looking to invest in South Africa. To conclude, it was found that South Africa has a very important role to play in attracting global FDI to Africa, as it has an accessible market based on geographic location, trade channels and traditional linkages with African and European networks.
- Full Text:
- Date Issued: 2019
- Authors: Van der Berg, Jan Gabriel Mara
- Date: 2019
- Subjects: Investments, Foreign -- South Africa , Business enterprises Business Organisations Industrial promotion
- Language: English
- Type: Thesis , Doctoral , DPhil
- Identifier: http://hdl.handle.net/10948/44213 , vital:37131
- Description: One of the major driving forces behind international trade over the past thirty years has been Foreign Direct Investment (FDI). Due to the importance of FDI, a vast amount of research has been conducted on the various elements that make up FDI. There has also been widespread research done to measure the impact of FDI on host countries, and attempts have been made to determine the long-term benefits thereof. Despite the existent research on FDI, there is a dearth of literature on the unique situation in South Africa (due to the country’s fragmented past) and the impact of FDI on the South African economy. This study attempts to address this research gap and to add to the existent body of knowledge on FDI market entry. Thus, the primary objective of this study was to examine the impact of multinational corporations (MNCs) in promoting the entry of FDIs in South Africa, and the effectiveness of these investments in the South African business environment. The comprehensive literature review in this study included a discussion of the background to the pre- and post-apartheid South African economy, and the various efforts made by the South African government to facilitate sustainable economic growth through various economic policies. FDI was identified as one of the four major indicators of economic growth and was therefore investigated as a concept, strategy and driver of change. The South African marketing environment was analysed in order to assist in the identification of variables that are conducive to FDI. The final section of the literature review utilised three cases to better illustrate and understand the different challenges, market entry strategies and long-term implications of FDI. In this study, the independent variables (international marketing environment, stakeholder intervention, government considerations, resources and FDI incentives) were identified as influencing the mediating variable (FDI market entry strategy) and the dependent variables (competitiveness, sustainability, trade agreements and commitment of traders). These independent variables were selected to construct a hypothesised model and the research hypotheses. To this end, an empirical investigation was conducted, the measuring instrument used in this investigation was a questionnaire, which was assembled with the help of insights gained from secondary sources. The study respondents were selected through convenience sampling. A total of 210 respondents participated in the study, and 165 useable questionnaires were subjected to statistical analysis. The data collected for this study was subjected to five phases of analysis: exploratory factor analysis to assess validity; Cronbach’s alpha was used to test for internal consistency reliability; descriptive statistics to describe the fundamental features of the data by providing a statistical summary and analysis; and the nine hypotheses pertaining to the relationships between different variables were assessed using inferential statistical procedures, Pearson’s product correlation and regression analysis. This led to the adaptation of the hypothesised model and the hypotheses so as to indicate the changes resulting from the EFA. The findings of this study reveals that external stakeholder intervention as well as FDI incentives and resources effectively influence FDI market entry strategy in the South African business environment. The study results further reveal that the promotion of FDI market entry strategy positively influences competitiveness, sustainability, trade agreements and commitment of traders in the South African business environment. For MNCs to be successful in the expansion of FDI market entry strategy in the South African business environment, the study recommends that it is important to consider the availability of potential local partners, proximity to trading routes, reduction of the costs involved in supplying the market, the effect of tariff barriers and a competitive domestic economy. It is further recommended that MNCs need to focus on the utilisation of reliable and effective equipment in order to enable the productive management of operations in the South African business environment. The study also recommends the South African business environment as a strategic investment destination for the promotion of FDI market entry strategy as it offers low production costs in particular trading locations. This study has contributed to the field of FDI and the FDI market entry strategies employed by MNCs in South Africa. The research findings identified the international marketing (SLEPTS) factors through an assessment of the South African marketing environment, as these factors are deemed important for FDI to occur. The study also highlights the critical international marketing factors that could be used to improve local conditions through a mixture of incentives and policy re-alignment, so as to be more conducive to attracting large scale FDI. The hypothesised model developed for this study contributed to identifying the influence of external stakeholders on the successful market entry of FDI into South Africa, a critical element that MNCs usually only identify after market entry is complete. Evidence from the study shows that the South African government should direct FDI incentives towards those sectors in the economy that stand to benefit the most from the spill-over effects of FDI, in order to maximise the impact of FDI on the local economy. The research also indicates that elements such as restrictive legislation and government corruption may, to a certain degree, hinder FDI; therefore, these issues need to be addressed through legislation. It is recommended that all local efforts to attract FDI are industry or sector focussed, and that they are guided by government policies towards the greater benefit of the South African economy. Furthermore, the study found that the relationship between the host country and the MNC is critical to achieving sustainability in the long-term; therefore, it is suggested that the South African government improves its relationship with local businesses and MNCs that are looking to invest in South Africa. To conclude, it was found that South Africa has a very important role to play in attracting global FDI to Africa, as it has an accessible market based on geographic location, trade channels and traditional linkages with African and European networks.
- Full Text:
- Date Issued: 2019
The social sustainability of low-cost housing: the role of social capital and sense of place
- Authors: Williams-Bruinders, Leizel
- Date: 2019
- Subjects: Housing -- South Africa , City planning -- South Africa Cities and towns -- Research Urban geography
- Language: English
- Type: Thesis , Doctoral , DPhil
- Identifier: http://hdl.handle.net/10948/44390 , vital:37161
- Description: In the past twenty years we have seen the South African government deliver the largest number of houses in the world (NDHS, 2011). However, this great effort does not appeal to the principles that policies have set out in terms of equality. Along with the delivery of this high level of state funded housing, many of the RDP dwellers feel as though they have been marginalised and forced out of the area of opportunity, namely, the CBD and the northern suburbs (Huchzermeyer, 2003). Many researchers believe that the South African housing delivery pattern resembles that of apartheid segregationist planning, which exacerbated the social inequalities in the country (Huchzermeyer, 2003; Donaldson, 2001; Harrison et al., 2003). To gain an in-depth understanding of the lived experiences of residents of a low-cost housing settlement, an interpretative phenomenological analysis was undertaken. The emergent themes emanating from the research study revealed that social problems were pertinent factors to the lack of formulation of community social cohesion. Without this aspect, community building will be hampered, and thus cohesive neighbourhoods will be lacking. To this end, social innovation is proposed as a solution to the Zanemvula development. The issue of social development needs to placed back on the housing agenda, as is stated in the latest Housing Act.
- Full Text:
- Date Issued: 2019
- Authors: Williams-Bruinders, Leizel
- Date: 2019
- Subjects: Housing -- South Africa , City planning -- South Africa Cities and towns -- Research Urban geography
- Language: English
- Type: Thesis , Doctoral , DPhil
- Identifier: http://hdl.handle.net/10948/44390 , vital:37161
- Description: In the past twenty years we have seen the South African government deliver the largest number of houses in the world (NDHS, 2011). However, this great effort does not appeal to the principles that policies have set out in terms of equality. Along with the delivery of this high level of state funded housing, many of the RDP dwellers feel as though they have been marginalised and forced out of the area of opportunity, namely, the CBD and the northern suburbs (Huchzermeyer, 2003). Many researchers believe that the South African housing delivery pattern resembles that of apartheid segregationist planning, which exacerbated the social inequalities in the country (Huchzermeyer, 2003; Donaldson, 2001; Harrison et al., 2003). To gain an in-depth understanding of the lived experiences of residents of a low-cost housing settlement, an interpretative phenomenological analysis was undertaken. The emergent themes emanating from the research study revealed that social problems were pertinent factors to the lack of formulation of community social cohesion. Without this aspect, community building will be hampered, and thus cohesive neighbourhoods will be lacking. To this end, social innovation is proposed as a solution to the Zanemvula development. The issue of social development needs to placed back on the housing agenda, as is stated in the latest Housing Act.
- Full Text:
- Date Issued: 2019
The synthesis and assessment of thioxanthone- and xanthone- derived compounds as hosts for application in host-guest chemistry
- Authors: Greyling, Lizé
- Date: 2019
- Subjects: Chemistry, Organic , Biochemistry
- Language: English
- Type: Thesis , Doctoral , DPhil
- Identifier: http://hdl.handle.net/10948/42525 , vital:36665
- Description: In this work, the host capabilities of two structurally related compounds, N,N’-bis(9-phenyl-9- thioxanthenyl)ethylenediamine (H1) and N,N’-bis(9-phenyl-9-xanthenyl)ethylenediamine (H2) were compared in the presence of a wide variety of guest species. Additionally, the selectivity displayed by these host compounds were examined when exposed to mixtures of guests in order to ascertain whether it would be feasible to employ them in alternative separation strategies for the purification of industrially relevant chemicals. H1 and H2 were synthesized by reacting thioxanthone and xanthone with phenylmagnesium bromide. The resultant alcohol was then treated with perchloric acid and, finally, two of these molecules were effectively linked by utilizing ethylenediamine to afford the two host compounds. Initially, H1 and H2 were investigated for their inclusion abilities by recrystallizing each from a number of potential isomeric and non-isomeric guest compounds such as the xylenes and ethylbenzene, methylanisoles and anisole, methylpyridines and pyridine, methylcyclohexanones and cyclohexanone, heterocyclic five- and six- membered ring compounds, alkylsubstituted benzenes, anilines, and dihaloalkanes. H1 displayed excellent inclusion ability when presented with the above-mentioned compounds, and a 1:1 H:G ratio was consistently preferred in each case. H2 also proved to be successful in this regard but did not include the methylcyclohexanones and cyclohexanone nor the heterocyclic five-membered ring solvents. Furthermore, varying host:guest ratios were observed for the complexes formed with H2. Mixed competition experiments were carried out in the presence of either isomeric or related but non-isomeric guest species. When H1 and H2 were independently recrystallized from mixtures of the former, selectivity orders correlated for both hosts, but it was observed that H2 exhibited an enhanced selectivity for the preferred guests in each case, compared with H1. Interestingly, in mixtures of the latter, host behaviours were distinctly opposing (with the exception of the dihaloalkanes). H1, and even more so H2, demonstrated very high selectivities for p-xylene, aniline and N,Ndimethylaniline from the xylene and aniline guest series, respectively, where selectivities were found to be ~90% or higher for host recrystallization experiments from respective mixtures of these guests. Single crystal X-ray diffraction, Hirshfeld surface and thermal analyses were employed in order to elucidate the reasons for any selectivity observations. The inclusion of these guests was, in most cases, found to be as a result of interactions between host and guest species, which included π∙∙∙π stacking, C‒H∙∙∙π, hydrogen bonding and various other short contact types. Guest compounds were accommodated in either cavities or channels and this was dependent on the nature of the guest. The host molecule conformations showed H1 to adopt a bent tricyclic fused ring system with the N atoms of the linker in a synclinal arrangement, while in complexes with H2, the fused ring system was near-planar and the N atoms adopted an antiperiplanar geometry. These key differences resulted in a very ordered host‒host packing for H2 as a direct result of the more planar O-containing ring and linear linker; for H1, on the other hand, the buckled S-containing ring and gauche-orientated N atoms resulted in a less ordered packing, which ultimately related to the differences in the behaviour of the two host species. Hirshfeld surface analyses, in general, did not provide much information to explain the host selectivities, with the exception of complexes containing the five-membered ring guest heterocyclics. Thermal analyses were completed on all suitable host-guest complexes and, in most cases but not all, the onset and peak temperatures (terms Ton and Tp, respectively) were related to the thermal stability of the complexes, which were used to rationalize the selectivities of these host compounds.
- Full Text:
- Date Issued: 2019
- Authors: Greyling, Lizé
- Date: 2019
- Subjects: Chemistry, Organic , Biochemistry
- Language: English
- Type: Thesis , Doctoral , DPhil
- Identifier: http://hdl.handle.net/10948/42525 , vital:36665
- Description: In this work, the host capabilities of two structurally related compounds, N,N’-bis(9-phenyl-9- thioxanthenyl)ethylenediamine (H1) and N,N’-bis(9-phenyl-9-xanthenyl)ethylenediamine (H2) were compared in the presence of a wide variety of guest species. Additionally, the selectivity displayed by these host compounds were examined when exposed to mixtures of guests in order to ascertain whether it would be feasible to employ them in alternative separation strategies for the purification of industrially relevant chemicals. H1 and H2 were synthesized by reacting thioxanthone and xanthone with phenylmagnesium bromide. The resultant alcohol was then treated with perchloric acid and, finally, two of these molecules were effectively linked by utilizing ethylenediamine to afford the two host compounds. Initially, H1 and H2 were investigated for their inclusion abilities by recrystallizing each from a number of potential isomeric and non-isomeric guest compounds such as the xylenes and ethylbenzene, methylanisoles and anisole, methylpyridines and pyridine, methylcyclohexanones and cyclohexanone, heterocyclic five- and six- membered ring compounds, alkylsubstituted benzenes, anilines, and dihaloalkanes. H1 displayed excellent inclusion ability when presented with the above-mentioned compounds, and a 1:1 H:G ratio was consistently preferred in each case. H2 also proved to be successful in this regard but did not include the methylcyclohexanones and cyclohexanone nor the heterocyclic five-membered ring solvents. Furthermore, varying host:guest ratios were observed for the complexes formed with H2. Mixed competition experiments were carried out in the presence of either isomeric or related but non-isomeric guest species. When H1 and H2 were independently recrystallized from mixtures of the former, selectivity orders correlated for both hosts, but it was observed that H2 exhibited an enhanced selectivity for the preferred guests in each case, compared with H1. Interestingly, in mixtures of the latter, host behaviours were distinctly opposing (with the exception of the dihaloalkanes). H1, and even more so H2, demonstrated very high selectivities for p-xylene, aniline and N,Ndimethylaniline from the xylene and aniline guest series, respectively, where selectivities were found to be ~90% or higher for host recrystallization experiments from respective mixtures of these guests. Single crystal X-ray diffraction, Hirshfeld surface and thermal analyses were employed in order to elucidate the reasons for any selectivity observations. The inclusion of these guests was, in most cases, found to be as a result of interactions between host and guest species, which included π∙∙∙π stacking, C‒H∙∙∙π, hydrogen bonding and various other short contact types. Guest compounds were accommodated in either cavities or channels and this was dependent on the nature of the guest. The host molecule conformations showed H1 to adopt a bent tricyclic fused ring system with the N atoms of the linker in a synclinal arrangement, while in complexes with H2, the fused ring system was near-planar and the N atoms adopted an antiperiplanar geometry. These key differences resulted in a very ordered host‒host packing for H2 as a direct result of the more planar O-containing ring and linear linker; for H1, on the other hand, the buckled S-containing ring and gauche-orientated N atoms resulted in a less ordered packing, which ultimately related to the differences in the behaviour of the two host species. Hirshfeld surface analyses, in general, did not provide much information to explain the host selectivities, with the exception of complexes containing the five-membered ring guest heterocyclics. Thermal analyses were completed on all suitable host-guest complexes and, in most cases but not all, the onset and peak temperatures (terms Ton and Tp, respectively) were related to the thermal stability of the complexes, which were used to rationalize the selectivities of these host compounds.
- Full Text:
- Date Issued: 2019
β-N-Methylamino-L-Alanine is a developmental neurotoxin
- Authors: Scott, Laura Louise
- Date: 2019
- Subjects: Neurotoxic agents , Nervous system -- Diseases
- Language: English
- Type: Thesis , Doctoral , DPhil
- Identifier: http://hdl.handle.net/10948/43633 , vital:36949
- Description: β-N-methylamino-L-alanine (BMAA) has been implicated in the development of the neurodegenerative diseases Amyotrophic Lateral Sclerosis/Parkinsonism Dementia Complex (ALS/PDC), Amyotrophic Lateral Sclerosis (ALS) and Alzheimer’s Disease (AD), but to date no animal model has adequately substantiated this link at environmentally relevant or even exaggerated BMAA exposure levels. The resulting controversy over a possible role for BMAA in neurodegenerative diseases was further hampered by a lack of evidence for mechanistic explanation for the disease pathology associated with these diseases However, the different responses to BMAA that have been observed in neonatal compared to adult rats, together with the findings of epidemiological studies that exposure to environmental factors in utero or in the early stages of life may be important for the development of ALS several years later, suggested that age of exposure might be the determining factor of BMAA neurotoxicity. This study therefore specifically addresses the developmental nature of BMAA as a neurotoxin, and investigates the pathology and progressive nature of that pathology after exposure to the toxin at the most susceptible age. This study demonstrated the importance of BMAA exposure age over total BMAA dose by showing that the administration of a single neonatal dose of BMAA to rodents on postnatal day (PND) 3, 4 and 5, and not prenatally or on PND 6, 7 and 10, caused behavioural, locomotor, emotional and long-term cognitive deficits, clinical symptoms of neurodegeneration as well as pathological hallmarks of AD, PD and ALS in the central nervous system. Furthermore, the observed behavioural deficits and distribution of neuronal loss and proteinopathies in the rodent central nervous system following exposure to BMAA on PND 3, 4 and 5 (corresponding to the developing age of an infant during the third trimester of pregnancy) is consistent with that typically associated with the disruption of normal dopamine and/or serotonin signaling in the brain and the consequent alteration in normal hippocampal and striatal neurogenesis that is modulated, in part, by dopamine. The pattern of spread and rate of propagation of pathology in this neonatal rat BMAA model provided further evidence that BMAA potentially exerts its effect by acting on neurotransmitter signaling. The observed late onset of typical ALS symptoms and pathology suggest that in this BMAA model AD and/or PD related symptoms develop first, followed by the start of ALS symptoms only after the AD and/or PD neuropathological deficits have severely progressed. This study also demonstrated that BMAA exposure at different doses and at different developmental ages resulted in the development of different combinations of either AD and/or PD and/or ALS pathology and/or symptoms in rats, and it is therefore feasible that in humans the age and/or frequency of exposure as well as the BMAA dose might similarly be a major determinant of the variant of AD, PD and/or ALS that might develop in adulthood. Based on the low BMAA dose that was able to cause AD and/or PD-like neuropathological abnormalities in rats in this study, it is feasible that a pregnant human could over the course of her pregnancy, and specifically during the third trimester of pregnancy, consume sufficient BMAA to result in her unborn child developing AD and/or PD and/or ALS up to 30-50 years later. This neonatal BMAA model is the only non-transgenic rodent model that reproduces the behavioural deficits, neuropathology and clinical symptoms that are typically associated with AD, PD and ALS in humans and that, more importantly, mimics the delayed onset of disease symptoms and typical slow progression of these neurodegenerative diseases with age. It now seems very likely that BMAA is a developmental neurotoxin that, as a result of perinatal, but probably prenatal exposure, causes or contributes significantly to the development of neurodegenerative diseases in humans.
- Full Text:
- Date Issued: 2019
- Authors: Scott, Laura Louise
- Date: 2019
- Subjects: Neurotoxic agents , Nervous system -- Diseases
- Language: English
- Type: Thesis , Doctoral , DPhil
- Identifier: http://hdl.handle.net/10948/43633 , vital:36949
- Description: β-N-methylamino-L-alanine (BMAA) has been implicated in the development of the neurodegenerative diseases Amyotrophic Lateral Sclerosis/Parkinsonism Dementia Complex (ALS/PDC), Amyotrophic Lateral Sclerosis (ALS) and Alzheimer’s Disease (AD), but to date no animal model has adequately substantiated this link at environmentally relevant or even exaggerated BMAA exposure levels. The resulting controversy over a possible role for BMAA in neurodegenerative diseases was further hampered by a lack of evidence for mechanistic explanation for the disease pathology associated with these diseases However, the different responses to BMAA that have been observed in neonatal compared to adult rats, together with the findings of epidemiological studies that exposure to environmental factors in utero or in the early stages of life may be important for the development of ALS several years later, suggested that age of exposure might be the determining factor of BMAA neurotoxicity. This study therefore specifically addresses the developmental nature of BMAA as a neurotoxin, and investigates the pathology and progressive nature of that pathology after exposure to the toxin at the most susceptible age. This study demonstrated the importance of BMAA exposure age over total BMAA dose by showing that the administration of a single neonatal dose of BMAA to rodents on postnatal day (PND) 3, 4 and 5, and not prenatally or on PND 6, 7 and 10, caused behavioural, locomotor, emotional and long-term cognitive deficits, clinical symptoms of neurodegeneration as well as pathological hallmarks of AD, PD and ALS in the central nervous system. Furthermore, the observed behavioural deficits and distribution of neuronal loss and proteinopathies in the rodent central nervous system following exposure to BMAA on PND 3, 4 and 5 (corresponding to the developing age of an infant during the third trimester of pregnancy) is consistent with that typically associated with the disruption of normal dopamine and/or serotonin signaling in the brain and the consequent alteration in normal hippocampal and striatal neurogenesis that is modulated, in part, by dopamine. The pattern of spread and rate of propagation of pathology in this neonatal rat BMAA model provided further evidence that BMAA potentially exerts its effect by acting on neurotransmitter signaling. The observed late onset of typical ALS symptoms and pathology suggest that in this BMAA model AD and/or PD related symptoms develop first, followed by the start of ALS symptoms only after the AD and/or PD neuropathological deficits have severely progressed. This study also demonstrated that BMAA exposure at different doses and at different developmental ages resulted in the development of different combinations of either AD and/or PD and/or ALS pathology and/or symptoms in rats, and it is therefore feasible that in humans the age and/or frequency of exposure as well as the BMAA dose might similarly be a major determinant of the variant of AD, PD and/or ALS that might develop in adulthood. Based on the low BMAA dose that was able to cause AD and/or PD-like neuropathological abnormalities in rats in this study, it is feasible that a pregnant human could over the course of her pregnancy, and specifically during the third trimester of pregnancy, consume sufficient BMAA to result in her unborn child developing AD and/or PD and/or ALS up to 30-50 years later. This neonatal BMAA model is the only non-transgenic rodent model that reproduces the behavioural deficits, neuropathology and clinical symptoms that are typically associated with AD, PD and ALS in humans and that, more importantly, mimics the delayed onset of disease symptoms and typical slow progression of these neurodegenerative diseases with age. It now seems very likely that BMAA is a developmental neurotoxin that, as a result of perinatal, but probably prenatal exposure, causes or contributes significantly to the development of neurodegenerative diseases in humans.
- Full Text:
- Date Issued: 2019