A case study on the incidence and extent of medullated and coloured fibres in the commercially produced South African wool clip 2010 – 2017
- Authors: Zietsman, Jolandrie
- Date: 2022-04
- Subjects: Port Elizabeth (South Africa) , Eastern Cape (South Africa) , South Africa
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10948/55445 , vital:52002
- Description: No formal study on the incidence and extent of medullated and coloured fibres has been performed in South Africa. The purpose of this research project was to investigate the validity of the claims that there has been an increase in the production of wool contaminated with medullated and coloured fibres. Therefore, the main aim of this study was to determine whether the incidence and extent of medullated and coloured fibres in the South African wool clip have changed over time. Secondly, the study aimed to determine whether the incidence and extent of medullated and coloured fibres have a distinct geographic distribution. This study explored eight years of wool production records (2010 to 2017) obtained from BKB, the largest wool broker in South Africa. For the purpose of this research, the wool-producing areas of South Africa were divided into 6 regions, according to average annual rainfall, vegetation type and major farming practices applied in the area. Statistical analysis of the data included descriptive statistics, analysis of variance and post-hoc tests, as well as regression analyses. This study succeeded in quantifying the extent and prevalence of contamination with medullated and coloured fibres in the South African wool clip. The overarching conclusions were: • Floating kemp is the most important contaminant of wool in South Africa, with the incidence of harsh kemp and coloured fibres being very low. • Generally, the most important areas that need attention in combatting contamination in the South African wool clip, are the Mixed Farming Summer Rainfall Region, the Semi-Arid Grassveld and the High Rainfall Grassland. , Thesis (MSc) -- Faculty of Science, School of Environmental Sciences, 2022
- Full Text:
- Date Issued: 2022-04
- Authors: Zietsman, Jolandrie
- Date: 2022-04
- Subjects: Port Elizabeth (South Africa) , Eastern Cape (South Africa) , South Africa
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10948/55445 , vital:52002
- Description: No formal study on the incidence and extent of medullated and coloured fibres has been performed in South Africa. The purpose of this research project was to investigate the validity of the claims that there has been an increase in the production of wool contaminated with medullated and coloured fibres. Therefore, the main aim of this study was to determine whether the incidence and extent of medullated and coloured fibres in the South African wool clip have changed over time. Secondly, the study aimed to determine whether the incidence and extent of medullated and coloured fibres have a distinct geographic distribution. This study explored eight years of wool production records (2010 to 2017) obtained from BKB, the largest wool broker in South Africa. For the purpose of this research, the wool-producing areas of South Africa were divided into 6 regions, according to average annual rainfall, vegetation type and major farming practices applied in the area. Statistical analysis of the data included descriptive statistics, analysis of variance and post-hoc tests, as well as regression analyses. This study succeeded in quantifying the extent and prevalence of contamination with medullated and coloured fibres in the South African wool clip. The overarching conclusions were: • Floating kemp is the most important contaminant of wool in South Africa, with the incidence of harsh kemp and coloured fibres being very low. • Generally, the most important areas that need attention in combatting contamination in the South African wool clip, are the Mixed Farming Summer Rainfall Region, the Semi-Arid Grassveld and the High Rainfall Grassland. , Thesis (MSc) -- Faculty of Science, School of Environmental Sciences, 2022
- Full Text:
- Date Issued: 2022-04
Variation in forage quality in subtropical thicket
- Nyembe, Khulisile Jacqueline
- Authors: Nyembe, Khulisile Jacqueline
- Date: 2021-04
- Subjects: Gqeberha (South Africa) , Eastern Cape (South Africa) , Biodiversity -- South Africa
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10948/52088 , vital:43440
- Description: Several studies have assumed that the plant communities of the Subtropical Thicket biome are nutritious throughout the year. This is based on the observation that they are evergreen, palatable and grow on fertile soils; however this assumption has not been tested. Therefore the aim of this study was to assess forage quality variation in the Subtropical Thicket. This was done at three levels; first we measured the plant quality of dominant plant species in the diets of Thicket herbivores. Secondly, we measured the realised diet quality of Thicket herbivores through the analysis of faecal samples. Lastly we assessed the body condition of Thicket herbivores. The study was conducted at the Colchester (plant quality and diet quality) and Addo Main Camp (body condition assessment) sections of Addo Elephant National Park. To measure the food quality of Thicket plants we analysed 10 plants that are dominant in the diets of Thicket herbivores. To measure diet quality we collected faecal samples from ten herbivores with body mass ranging from 25 kg to 6000 kg. Plant quality results showed that only 30% of the sampled plants met the high energy goat diet protein requirements and that all the sampled plants did not meet the high energy goat diet fibre requirements. This indicates that Thicket plants are not as highly nutritious as they were thought to be. The principle components analysis together with overlapping confidence intervals showed that there was no significant difference between the summer plant samples and the winter plant samples. The faecal quality results showed that there was significant seasonal difference and that faecal diet quality was a function of body size. The body condition results showed that all the sampled herbivores lost condition in the cold dry months. The evidence from faecal diet quality and body condition assessment is sufficient for us to reject the assumption that Thicket forage is consistently nutritious throughout the year. , Thesis (MSc) -- Faculty of Science, School of Environmental Sciences, 2021
- Full Text: false
- Date Issued: 2021-04
- Authors: Nyembe, Khulisile Jacqueline
- Date: 2021-04
- Subjects: Gqeberha (South Africa) , Eastern Cape (South Africa) , Biodiversity -- South Africa
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10948/52088 , vital:43440
- Description: Several studies have assumed that the plant communities of the Subtropical Thicket biome are nutritious throughout the year. This is based on the observation that they are evergreen, palatable and grow on fertile soils; however this assumption has not been tested. Therefore the aim of this study was to assess forage quality variation in the Subtropical Thicket. This was done at three levels; first we measured the plant quality of dominant plant species in the diets of Thicket herbivores. Secondly, we measured the realised diet quality of Thicket herbivores through the analysis of faecal samples. Lastly we assessed the body condition of Thicket herbivores. The study was conducted at the Colchester (plant quality and diet quality) and Addo Main Camp (body condition assessment) sections of Addo Elephant National Park. To measure the food quality of Thicket plants we analysed 10 plants that are dominant in the diets of Thicket herbivores. To measure diet quality we collected faecal samples from ten herbivores with body mass ranging from 25 kg to 6000 kg. Plant quality results showed that only 30% of the sampled plants met the high energy goat diet protein requirements and that all the sampled plants did not meet the high energy goat diet fibre requirements. This indicates that Thicket plants are not as highly nutritious as they were thought to be. The principle components analysis together with overlapping confidence intervals showed that there was no significant difference between the summer plant samples and the winter plant samples. The faecal quality results showed that there was significant seasonal difference and that faecal diet quality was a function of body size. The body condition results showed that all the sampled herbivores lost condition in the cold dry months. The evidence from faecal diet quality and body condition assessment is sufficient for us to reject the assumption that Thicket forage is consistently nutritious throughout the year. , Thesis (MSc) -- Faculty of Science, School of Environmental Sciences, 2021
- Full Text: false
- Date Issued: 2021-04
Plastic particle characterization and concentrations found in the river and marine water environment of Algoa Bay, South Africa
- Authors: Moss, Kerry-Leigh
- Date: 2021-12
- Subjects: Port Elizabeth (South Africa) , Eastern Cape (South Africa) , South Africa
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10948/53874 , vital:46025
- Description: Only 12% of the world's published plastic research includes references to Africa despite it being a significant contributor to the global plastic waste and mismanagement problem (~88.5% of Africa's plastic waste is mismanaged). Ocean plastics are transported from land by rivers to the sea. However, source contextualization is complex. Many African rivers predominantly run alongside human settlements that host informal waste dumpsites. In this study a simple cost effective, easily deployed, consistent and replicable survey methodology was employed. The study quantified macro plastic in three rivers discharging into Algoa Bay, South Africa. The results indicated that industrial Swartkops and metropolitan Baakens Rivers both illustrate moderate plastic pollution (>3000 plastic particles/day), with the relatively natural Sundays River to showing minimal evidence of river macroplastic (<100 plastic particles/day). The types of plastic were noted using the RIMMEL app (premier African implementation), enabling proportional comparison of different plastic litter types to be completed. , Thesis (MSc) -- Faculty of Science, Oceanography Department,2021
- Full Text:
- Date Issued: 2021-12
- Authors: Moss, Kerry-Leigh
- Date: 2021-12
- Subjects: Port Elizabeth (South Africa) , Eastern Cape (South Africa) , South Africa
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10948/53874 , vital:46025
- Description: Only 12% of the world's published plastic research includes references to Africa despite it being a significant contributor to the global plastic waste and mismanagement problem (~88.5% of Africa's plastic waste is mismanaged). Ocean plastics are transported from land by rivers to the sea. However, source contextualization is complex. Many African rivers predominantly run alongside human settlements that host informal waste dumpsites. In this study a simple cost effective, easily deployed, consistent and replicable survey methodology was employed. The study quantified macro plastic in three rivers discharging into Algoa Bay, South Africa. The results indicated that industrial Swartkops and metropolitan Baakens Rivers both illustrate moderate plastic pollution (>3000 plastic particles/day), with the relatively natural Sundays River to showing minimal evidence of river macroplastic (<100 plastic particles/day). The types of plastic were noted using the RIMMEL app (premier African implementation), enabling proportional comparison of different plastic litter types to be completed. , Thesis (MSc) -- Faculty of Science, Oceanography Department,2021
- Full Text:
- Date Issued: 2021-12
Spatial and temporal analysis of the critical zone in the Western rift valley corridor: towards earth stewardship science in East Africa
- Authors: Miller, Warren David
- Date: 2022-12
- Subjects: Port Elizabeth (South Africa) , Eastern Cape (South Africa) , South Africa
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10948/59771 , vital:62423
- Description: Over the coming decades, Africa is expected to experience disturbing effects due to climate change and increased land cover change due to human influences presenting a significant concern for the future well-being of human and biological systems, the latter being the foundation of ecosystem services supplied to humanity. Therefore, unprecedented transdisciplinary cooperation, coordination, and integration amongst researchers, government, and civil society are necessary to increase the resiliency of these systems. This study aims to provide an outline of the Africa Alive Corridors (AAC) as an essential model for the encouragement of sustainable development through Earth Stewardship science. These aims are accompanied by the quantification and forward modelling for land cover change of the Critical Zone over 10 Great Lake Basins across one of the AAC, the Western Rift Valley Corridor (WRVC), in East Africa between the years 2018 and 2060. This approach provides the foundation for implementing improved regional governance, better encouragement of sustainable development beyond the 2030 United Nations Sustainable Development Goals, and education programs, such as the AAC, that promote socio-ecological resilience through Earth Stewardship Science. The AAC archives a portion of East Africa as the WRVC, a corridor along the western branch of the East African Rift System that highlights twenty heritage nodes, primarily great lakes, mountain ranges, national parks, and biological hotspots. These heritage entities are associated with ca. 12-million-years of evolution and transformation of the East African topography and related African Great Lake (AGL) systems. The thesis defines the study area by delineating AGL basins intersected by the WRVC. Across these basins, land cover change analysis provides a platform for an integrated assessment of the projected health of the corridor region. Existing land cover datasets provide the initial conditions of the study area for 2008 and 2013. Land cover between 2008 and 2013 is cross-tabulated using the Land Cover Module in the Terrset software, followed by the iii delineation of sub-models and driver variable identification. The Multi-Layer Perceptron algorithm provides the transition potentials between tree cover, urban area, cropland, wetland, and open area classes. Change quantification and prediction using Markov Chain analysis are then established for 2018, 2030, and 2060. The model successfully simulated future land cover change and concluded that: (1) proximity to existing human activity, proximity to existing tree cover, and population are the primary drivers of change; (2) the dominant land cover of the ten lake basins for 2018 was cropland at ca. 48%, followed by tree cover at ca. 33%; (3) total anthropogenic change over the coming four decades equates to over ca. 52 000 km2 (5 200 000 ha), and particularly (4) an urban area is expected to increase by >130%. This assessment ultimately provides a platform for regional governance development at the basin scale and Earth Stewardship science in East Africa. These changes require transdisciplinary action from researchers to civil society. The AAC provides the foundation for understanding the dynamics of the systems that support life across broader spatial and temporal resolutions in Africa, highlighting the need for future generations to build socio-ecological resilience to anticipate challenges such as biodiversity loss posed by climate change and excessive land cover change. , Thesis (DSc) -- Faculty of Science, School of Environmental Sciences, 2022
- Full Text:
- Date Issued: 2022-12
- Authors: Miller, Warren David
- Date: 2022-12
- Subjects: Port Elizabeth (South Africa) , Eastern Cape (South Africa) , South Africa
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10948/59771 , vital:62423
- Description: Over the coming decades, Africa is expected to experience disturbing effects due to climate change and increased land cover change due to human influences presenting a significant concern for the future well-being of human and biological systems, the latter being the foundation of ecosystem services supplied to humanity. Therefore, unprecedented transdisciplinary cooperation, coordination, and integration amongst researchers, government, and civil society are necessary to increase the resiliency of these systems. This study aims to provide an outline of the Africa Alive Corridors (AAC) as an essential model for the encouragement of sustainable development through Earth Stewardship science. These aims are accompanied by the quantification and forward modelling for land cover change of the Critical Zone over 10 Great Lake Basins across one of the AAC, the Western Rift Valley Corridor (WRVC), in East Africa between the years 2018 and 2060. This approach provides the foundation for implementing improved regional governance, better encouragement of sustainable development beyond the 2030 United Nations Sustainable Development Goals, and education programs, such as the AAC, that promote socio-ecological resilience through Earth Stewardship Science. The AAC archives a portion of East Africa as the WRVC, a corridor along the western branch of the East African Rift System that highlights twenty heritage nodes, primarily great lakes, mountain ranges, national parks, and biological hotspots. These heritage entities are associated with ca. 12-million-years of evolution and transformation of the East African topography and related African Great Lake (AGL) systems. The thesis defines the study area by delineating AGL basins intersected by the WRVC. Across these basins, land cover change analysis provides a platform for an integrated assessment of the projected health of the corridor region. Existing land cover datasets provide the initial conditions of the study area for 2008 and 2013. Land cover between 2008 and 2013 is cross-tabulated using the Land Cover Module in the Terrset software, followed by the iii delineation of sub-models and driver variable identification. The Multi-Layer Perceptron algorithm provides the transition potentials between tree cover, urban area, cropland, wetland, and open area classes. Change quantification and prediction using Markov Chain analysis are then established for 2018, 2030, and 2060. The model successfully simulated future land cover change and concluded that: (1) proximity to existing human activity, proximity to existing tree cover, and population are the primary drivers of change; (2) the dominant land cover of the ten lake basins for 2018 was cropland at ca. 48%, followed by tree cover at ca. 33%; (3) total anthropogenic change over the coming four decades equates to over ca. 52 000 km2 (5 200 000 ha), and particularly (4) an urban area is expected to increase by >130%. This assessment ultimately provides a platform for regional governance development at the basin scale and Earth Stewardship science in East Africa. These changes require transdisciplinary action from researchers to civil society. The AAC provides the foundation for understanding the dynamics of the systems that support life across broader spatial and temporal resolutions in Africa, highlighting the need for future generations to build socio-ecological resilience to anticipate challenges such as biodiversity loss posed by climate change and excessive land cover change. , Thesis (DSc) -- Faculty of Science, School of Environmental Sciences, 2022
- Full Text:
- Date Issued: 2022-12
Spatial modelling of accessibility to tuberculosis treatment: the case of Ngaka Modiri Molema District
- Authors: Ramotsongwa, Karabo Naome
- Date: 2022-04
- Subjects: Port Elizabeth (South Africa) , Eastern Cape (South Africa) , South Africa
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10948/55435 , vital:52000
- Description: Accessibility to healthcare refers to the availability, or the provision of healthcare-byhealthcare professionals and stakeholders and individuals' ability to obtain care and treatment. It affects overall physical, social, and mental health; disease and disability prevention; detection and treatment of health conditions; standard of living; preventable death; and life expectancy, and it is crucial to the performance of health care systems around the world. If healthcare services are available and are in sufficient supply, people will be able to seek health care, and a population will have access to services. The leading cause of death globally is Tuberculosis (TB) and South Africa is amongst the top 5 countries most affected by TB. This is aggravated by high HIV/AIDS statistics. Children belowthe age of 4, between the ages of 4- 15, and women and men of working ages are highly affected by TB and it is the primary cause of death in these groups in the Ngaka Modiri Molema District. This study used study tools like Spatial Modelling, Geographic Information Systems and software like ArcGIS 10.5, TerrSet IDRISI 18.30, and secondary data from the North West Departmentof Health (Tier.net &DHIS) and also TB patients’ home addresses to investigate the accessibility of TB treatment in Ngaka Modiri Molema, in order to spatially visualize the distribution of a communicable disease like TB and public healthcare facilities in the Ngaka Modiri Molema (NMM) District and suggest optimum sites for hospital facilities. , Thesis (MSc) -- Faculty of Science, School of Environmental Sciences, 2022
- Full Text:
- Date Issued: 2022-04
- Authors: Ramotsongwa, Karabo Naome
- Date: 2022-04
- Subjects: Port Elizabeth (South Africa) , Eastern Cape (South Africa) , South Africa
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10948/55435 , vital:52000
- Description: Accessibility to healthcare refers to the availability, or the provision of healthcare-byhealthcare professionals and stakeholders and individuals' ability to obtain care and treatment. It affects overall physical, social, and mental health; disease and disability prevention; detection and treatment of health conditions; standard of living; preventable death; and life expectancy, and it is crucial to the performance of health care systems around the world. If healthcare services are available and are in sufficient supply, people will be able to seek health care, and a population will have access to services. The leading cause of death globally is Tuberculosis (TB) and South Africa is amongst the top 5 countries most affected by TB. This is aggravated by high HIV/AIDS statistics. Children belowthe age of 4, between the ages of 4- 15, and women and men of working ages are highly affected by TB and it is the primary cause of death in these groups in the Ngaka Modiri Molema District. This study used study tools like Spatial Modelling, Geographic Information Systems and software like ArcGIS 10.5, TerrSet IDRISI 18.30, and secondary data from the North West Departmentof Health (Tier.net &DHIS) and also TB patients’ home addresses to investigate the accessibility of TB treatment in Ngaka Modiri Molema, in order to spatially visualize the distribution of a communicable disease like TB and public healthcare facilities in the Ngaka Modiri Molema (NMM) District and suggest optimum sites for hospital facilities. , Thesis (MSc) -- Faculty of Science, School of Environmental Sciences, 2022
- Full Text:
- Date Issued: 2022-04
Encapsulation of flame retardants for lithium-ion battery safety
- Authors: Ntombela, Nompilo Princess
- Date: 2022-04
- Subjects: Port Elizabeth (South Africa) , Eastern Cape (South Africa) , South Africa
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10948/55412 , vital:51993
- Description: Lithium-ion technology takes the lead in electric mobility systems, resulting in an increase in the global demand for Li-ion batteries; however, these batteries are associated with numerous safety concerns. Additionally, there are high costs, high energy and power issues which are some of its key limitations. Research efforts are focused on overcoming these obstacles, with different approaches being explored, such as the investigation of more stable salts, modification of active materials and organic solvents, and the use of electrolyte additives. This study focused specifically on electrolyte additives since the electrolyte is one of the most unstable components of the battery. The electrolyte’s decomposition is one of the reactions that occur inside a battery, which may occur due to overcharging or due to an internal short circuit, amongst others. The electrolyte’s decomposition occurs at the early stages of the thermal runaway process and forms part of the reactions that lead to fires and explosions. Thus, this research aims to develop suitable electrolyte additives to improve the safety aspects of Li-ion batteries. Flame retardant additives show great promise in reducing the flammability of the electrolyte in Li-ion batteries, since they serve to suppress the chemical reactions associated with battery ignition. They retard the fires by scavenging the active radical species formed during the decomposition reaction. In this study, the use of flame retardants was investigated. Flame retardant additives have shown to have flame impeding properties inside a battery; however, their direct addition to the electrolyte tends to cause adverse effects on the ionic conductivity and electrochemical performance of the cells. This study investigated an alternative option - the option to microencapsulate such additives into a neutral compound to ensure that the flame retardant has minimal/no effect on the performance of the battery. This investigation looked at tris(2-butoxyethyl) phosphate (TBP) and bis(2,2,2-trifluoroethyl) methylphosphonate (BFP) as flame retardant additives for the electrolyte. The TBP and BFP flame retardants were microencapsulated in poly(urea formaldehyde) (PUF) coating material via in situ polymerization method. The capsules were characterized using various analytical techniques - to prove it was successfully encapsulated. Electrochemical studies were further done on the capsules and neat flame retardants inside a coin cell. Self-extinguishing time (SET), which is the flammability test, proved that the additives have flame retarding abilities. Opto-digital microscopy (DSX) and scanning electron microscopy (SEM) did confirm the spherical shape of the microcapsules, where SEM also showed the smooth outer layer of the microcapsules and its hollow inner side. Fourier transform infrared spectroscopy (FTIR) proved the presence of the TBP and BFP inside the PUF resin by showing that the chemical composition of microcapsules consisted of both the PUF and flame retardant additives. Simultaneous DSC-TGA (DST) was also performed which showed that the microcapsules were stable before 200 °C, which indicates it would not decompose before the thermal runaway events are occurring. TGA analysis did show that the microcapsules underwent multiple decomposition steps upon heating. Additionally, 31P nuclear magnetic resonance (NMR) was used to quantify the amount of flame retardants additives encapsulated inside PUF shell, and also confirmed the stability of the microcapsules for one month in the electrolyte and at temperatures up to 200 °C. The ionic conductivity was vastly decreased when the flame retardants were added directly to the electrolyte. However, adding the flame retardants in a form of capsules had minimal effect on the ionic conductivity. The cycle capacities of the capsules were also improved when the capsules were added to the cell compared to that of neat flame retardants. The same effect was also noticed when doing Electrochemical Impedance Spectroscopy (EIS). This shows that microencapsulation improves the resistance of the cell caused by the flame retardant in comparison to when added directly to the electrolyte of the cell. , Thesis (MSC) -- Faculty of Science, School of Biomolecular and Chemical Sciences, 2022
- Full Text:
- Date Issued: 2022-04
- Authors: Ntombela, Nompilo Princess
- Date: 2022-04
- Subjects: Port Elizabeth (South Africa) , Eastern Cape (South Africa) , South Africa
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10948/55412 , vital:51993
- Description: Lithium-ion technology takes the lead in electric mobility systems, resulting in an increase in the global demand for Li-ion batteries; however, these batteries are associated with numerous safety concerns. Additionally, there are high costs, high energy and power issues which are some of its key limitations. Research efforts are focused on overcoming these obstacles, with different approaches being explored, such as the investigation of more stable salts, modification of active materials and organic solvents, and the use of electrolyte additives. This study focused specifically on electrolyte additives since the electrolyte is one of the most unstable components of the battery. The electrolyte’s decomposition is one of the reactions that occur inside a battery, which may occur due to overcharging or due to an internal short circuit, amongst others. The electrolyte’s decomposition occurs at the early stages of the thermal runaway process and forms part of the reactions that lead to fires and explosions. Thus, this research aims to develop suitable electrolyte additives to improve the safety aspects of Li-ion batteries. Flame retardant additives show great promise in reducing the flammability of the electrolyte in Li-ion batteries, since they serve to suppress the chemical reactions associated with battery ignition. They retard the fires by scavenging the active radical species formed during the decomposition reaction. In this study, the use of flame retardants was investigated. Flame retardant additives have shown to have flame impeding properties inside a battery; however, their direct addition to the electrolyte tends to cause adverse effects on the ionic conductivity and electrochemical performance of the cells. This study investigated an alternative option - the option to microencapsulate such additives into a neutral compound to ensure that the flame retardant has minimal/no effect on the performance of the battery. This investigation looked at tris(2-butoxyethyl) phosphate (TBP) and bis(2,2,2-trifluoroethyl) methylphosphonate (BFP) as flame retardant additives for the electrolyte. The TBP and BFP flame retardants were microencapsulated in poly(urea formaldehyde) (PUF) coating material via in situ polymerization method. The capsules were characterized using various analytical techniques - to prove it was successfully encapsulated. Electrochemical studies were further done on the capsules and neat flame retardants inside a coin cell. Self-extinguishing time (SET), which is the flammability test, proved that the additives have flame retarding abilities. Opto-digital microscopy (DSX) and scanning electron microscopy (SEM) did confirm the spherical shape of the microcapsules, where SEM also showed the smooth outer layer of the microcapsules and its hollow inner side. Fourier transform infrared spectroscopy (FTIR) proved the presence of the TBP and BFP inside the PUF resin by showing that the chemical composition of microcapsules consisted of both the PUF and flame retardant additives. Simultaneous DSC-TGA (DST) was also performed which showed that the microcapsules were stable before 200 °C, which indicates it would not decompose before the thermal runaway events are occurring. TGA analysis did show that the microcapsules underwent multiple decomposition steps upon heating. Additionally, 31P nuclear magnetic resonance (NMR) was used to quantify the amount of flame retardants additives encapsulated inside PUF shell, and also confirmed the stability of the microcapsules for one month in the electrolyte and at temperatures up to 200 °C. The ionic conductivity was vastly decreased when the flame retardants were added directly to the electrolyte. However, adding the flame retardants in a form of capsules had minimal effect on the ionic conductivity. The cycle capacities of the capsules were also improved when the capsules were added to the cell compared to that of neat flame retardants. The same effect was also noticed when doing Electrochemical Impedance Spectroscopy (EIS). This shows that microencapsulation improves the resistance of the cell caused by the flame retardant in comparison to when added directly to the electrolyte of the cell. , Thesis (MSC) -- Faculty of Science, School of Biomolecular and Chemical Sciences, 2022
- Full Text:
- Date Issued: 2022-04
Estimating activity patterns in camera trap studies, and the overlap between domestic and indigenous ungulates
- Authors: Peral, Christopher Michael
- Date: 2021-04
- Subjects: Gqeberha (South Africa) , Eastern Cape (South Africa) , Ungulates -- Behavior -- South Africa
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10948/52019 , vital:43437
- Description: Animal activity can reveal responses to social and ecological factors such as the presence of food, water, shelter, predators, competitors or conspecifics. Thus, an understanding of an animal’s activity patterns provides insights into how and why they are using landscapes in the manner in which they do. Camera trap surveys, typically used to record the occurrence of species of interest, are also an efficient way to collect data regarding animal activity patterns but require robust analytical methods. The analysis of camera trap data requires assumptions that may differ for camera trap surveys that estimate occurrence or activity. One such assumption is temporal independence. This refers to the removal of images within a specified time interval, as these images are assumed to be images of the same individual. This assumption stems from the use of-time-to-independence in occurrence or density-based studies, where it reduces overestimation of animal counts. In studies of animal activity, this assumption is generally used, even though animal behaviour or activity occurs continuously over time and as such should be measured over time. I analysed 112 467 images of eight cooccurring species, to test the effect across various times to independence, these being set at 1, 5, 10, 15, 30 and 60 minutes. Time-to-independence resulted in significant loss of data and biased the interpretation of the activity patterns of species and interactions amongst species, particularly for herbivorous social species. In light of these findings, activity pattern estimates based on camera trap studies should be cautious when using time-to-independence. I then explore ‘habitat use’ in space and time by domestic and indigenous ungulates using a camera trap survey. Domestic ungulates (livestock) have become common place on rangelands and may compete with native species. It was hypothesised that there will be overlap in habitat use by livestock and indigenous ungulates. My results show that indigenous ungulate species, particularly larger species such as kudu (Tragelaphus strepsiceros) and springbok (Antidorcas marsupialis), changed their spatial and temporal use as a result of the presence of domestic ungulates. Other smaller indigenous ungulates, such as steenbok (Raphicerus campestris) and duiker (Sylvicapra grimmia), were less affected by the presence of livestock. Kudu were found to use more open habitats at different times whilst springbok used more dense habitats at different times in the presence of livestock. This supports the hypothesis of competition between livestock and indigenous ungulates. This study provides novel insight into the analysis and interpretation of activity patterns based on camera trap surveys. Additionally, this study demonstrates the competitive displacement between domestic and indigenous ungulate species. , Thesis (MSc) -- Faculty of Science, School of Environmental Sciences, 2021
- Full Text: false
- Date Issued: 2021-04
- Authors: Peral, Christopher Michael
- Date: 2021-04
- Subjects: Gqeberha (South Africa) , Eastern Cape (South Africa) , Ungulates -- Behavior -- South Africa
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10948/52019 , vital:43437
- Description: Animal activity can reveal responses to social and ecological factors such as the presence of food, water, shelter, predators, competitors or conspecifics. Thus, an understanding of an animal’s activity patterns provides insights into how and why they are using landscapes in the manner in which they do. Camera trap surveys, typically used to record the occurrence of species of interest, are also an efficient way to collect data regarding animal activity patterns but require robust analytical methods. The analysis of camera trap data requires assumptions that may differ for camera trap surveys that estimate occurrence or activity. One such assumption is temporal independence. This refers to the removal of images within a specified time interval, as these images are assumed to be images of the same individual. This assumption stems from the use of-time-to-independence in occurrence or density-based studies, where it reduces overestimation of animal counts. In studies of animal activity, this assumption is generally used, even though animal behaviour or activity occurs continuously over time and as such should be measured over time. I analysed 112 467 images of eight cooccurring species, to test the effect across various times to independence, these being set at 1, 5, 10, 15, 30 and 60 minutes. Time-to-independence resulted in significant loss of data and biased the interpretation of the activity patterns of species and interactions amongst species, particularly for herbivorous social species. In light of these findings, activity pattern estimates based on camera trap studies should be cautious when using time-to-independence. I then explore ‘habitat use’ in space and time by domestic and indigenous ungulates using a camera trap survey. Domestic ungulates (livestock) have become common place on rangelands and may compete with native species. It was hypothesised that there will be overlap in habitat use by livestock and indigenous ungulates. My results show that indigenous ungulate species, particularly larger species such as kudu (Tragelaphus strepsiceros) and springbok (Antidorcas marsupialis), changed their spatial and temporal use as a result of the presence of domestic ungulates. Other smaller indigenous ungulates, such as steenbok (Raphicerus campestris) and duiker (Sylvicapra grimmia), were less affected by the presence of livestock. Kudu were found to use more open habitats at different times whilst springbok used more dense habitats at different times in the presence of livestock. This supports the hypothesis of competition between livestock and indigenous ungulates. This study provides novel insight into the analysis and interpretation of activity patterns based on camera trap surveys. Additionally, this study demonstrates the competitive displacement between domestic and indigenous ungulate species. , Thesis (MSc) -- Faculty of Science, School of Environmental Sciences, 2021
- Full Text: false
- Date Issued: 2021-04
Linking agrochemical pollution with the aquatic ecological integrity of the Twee River Catchment, Western Cape
- Authors: Brink, Zanné
- Date: 2021-04
- Subjects: Gqeberha (South Africa) , Eastern Cape (South Africa) , Ecological integrity
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10948/52326 , vital:43588
- Description: This study was initiated in the Twee River system due to the threat posed by agrochemicals on the occurrence of the endemic and endangered fish species found within the catchment. Poor knowledge and understanding of the environmental effects of fertilizers, pesticides and other agrochemicals among small and large commercial farmers within the study area, in combination with their intensive use may have resulted in chemical contamination above environmentally safe concentrations. Numerous studies have highlighted the fact that more research needs to be conducted to identify the key threats to the continued existence of specifically the Critically Endangered Sedercypris erubescens. The overall aim of this study was to determine the spatial and temporal patterns in aquatic ecosystem diversity in the Twee River catchment as indicated by macroinvertebrate and native fish distribution and abundance. It was further investigated if there was a link between agrochemical pollution and the aquatic ecological integrity of the Twee River catchment. Selected sampling sites were identified and sampled to determine the presence and concentration of pesticides entering the water of the Twee River system during run-off and event-based spraying. Furthermore, the effect of these pesticides on the distribution and abundance of the aquatic biota were determined using SASS5 for the macroinvertebrate populations and visually sampling the distribution of the native and non-native fish in the Twee River catchment. This study supports suggestions made by previous studies, that sub-lethal to lethal concentrations of insecticides could be a threat to the long-term survival of benthic macroinvertebrates and potentially the more sensitive endemic fish species within the Twee River system. More focussed research is needed to address impacts of pesticides within this catchment. Agricultural and conservation efforts should be aimed at developing of a shared vision amongst stakeholders, to allow for the longterm conservation of the endemic fish of the Twee River. , Thesis (MSc) -- Faculty of Science, School of Natural Resource Management, 2021
- Full Text: false
- Date Issued: 2021-04
- Authors: Brink, Zanné
- Date: 2021-04
- Subjects: Gqeberha (South Africa) , Eastern Cape (South Africa) , Ecological integrity
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10948/52326 , vital:43588
- Description: This study was initiated in the Twee River system due to the threat posed by agrochemicals on the occurrence of the endemic and endangered fish species found within the catchment. Poor knowledge and understanding of the environmental effects of fertilizers, pesticides and other agrochemicals among small and large commercial farmers within the study area, in combination with their intensive use may have resulted in chemical contamination above environmentally safe concentrations. Numerous studies have highlighted the fact that more research needs to be conducted to identify the key threats to the continued existence of specifically the Critically Endangered Sedercypris erubescens. The overall aim of this study was to determine the spatial and temporal patterns in aquatic ecosystem diversity in the Twee River catchment as indicated by macroinvertebrate and native fish distribution and abundance. It was further investigated if there was a link between agrochemical pollution and the aquatic ecological integrity of the Twee River catchment. Selected sampling sites were identified and sampled to determine the presence and concentration of pesticides entering the water of the Twee River system during run-off and event-based spraying. Furthermore, the effect of these pesticides on the distribution and abundance of the aquatic biota were determined using SASS5 for the macroinvertebrate populations and visually sampling the distribution of the native and non-native fish in the Twee River catchment. This study supports suggestions made by previous studies, that sub-lethal to lethal concentrations of insecticides could be a threat to the long-term survival of benthic macroinvertebrates and potentially the more sensitive endemic fish species within the Twee River system. More focussed research is needed to address impacts of pesticides within this catchment. Agricultural and conservation efforts should be aimed at developing of a shared vision amongst stakeholders, to allow for the longterm conservation of the endemic fish of the Twee River. , Thesis (MSc) -- Faculty of Science, School of Natural Resource Management, 2021
- Full Text: false
- Date Issued: 2021-04
Optimizing herbicide-use for the killing of eucalypt stumps
- Authors: Mavhungu, Tshilidzi
- Date: 2021-12
- Subjects: Port Elizabeth (South Africa) , Eastern Cape (South Africa) , South Africa
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10948/53857 , vital:46023
- Description: The South Africa (SA) forest industry relies on plantations of exotic forestry trees (Pinus, Acacia and Eucalyptus) to fulfil its timber requirements. With 52.0% of the afforested land in South Africa planted to various eucalypts and their hybrid combinations. Of the total area planted to eucalypts in SA, 75 000 ha is re-established annually by means of silvicultural regimes and operations matched to site productivity, desired end-product and method of regeneration. Unlike other commercially grown tree species, eucalypt species have the ability to coppice after felling. Coppicing is a common form of regeneration in South African forestry as it allows the plantation owner the option of a second timber rotation without replanting. However, if any factors affecting coppicing are compromised, and the site is to be replanted, then it is important to kill the stumps before replanting as rapid initial growth of the coppice shoots will require earlier control than that associated with normal weeding operations. Over time, various methods of woody plant control have been proposed and tested, with most of these making use of herbicides as opposed to the repeated manual removal of coppice regrowth. Globally, most industries subscribe to standards associated with sustainable production (economic, environmental and social) against which they are measured. Within SA, 80% of the forests are certified though either the Forest Stewardship Council (FSC) or International Standards Organisation (ISO) which recommend the identification and avoidance of ‘highly hazardous’ chemicals; the promotion of ‘non-chemical’ methods for pest management as an element of an integrated pest and vegetation management strategy; and the appropriate use of chemicals that are used. To test the current recommendations for killing eucalypt stumps to include other species, the potential of reducing herbicides used, and the influence of time after application on the survival of eucalypt stumps, two trials were initiated at Entabeni plantation (Venda, Limpopo) and one at Wilgeboom plantation (Bushbuckridge, Mpumalanga) between 2018 and 2020. Extending eucalypt cut-stump control practices: Most of the trial work on killing of eucalypts in SA has been conducted on Eucalyptus grandis, Eucalyptus camaldulensis or Eucalyptus macarthurii, with all grown on shorter pulpwood rotations. To extend current recommendation to include Eucalyptus cloeziana (grown on a longer rotation for poles), a trial was established in 2018 at Entabeni plantation (Limpopo Province) to quantify the interaction between Application method (basal-frill; cut-surface; foliar) and Herbicide (no herbicide applied; Roundup; Garlon; Roundup + Garlon) for the killing of 12 year-old stumps following harvesting. Assessments were carried out at 1, 3 and 6 months following application and included Stump survival, Stump quarter with coppice and Coppice heath. Relative to the control plots (100% survival), all herbicides tested were equally effective, 70–90% of the stumps killed. This study confirms previous research regarding the killing of eucalypt stumps. Roundup, Garlon or a combination of two, when applied according to label recommendations to a stump as a basal-frill or cut-surface application (within 30 minutes of felling) resulted in 70-90% of the stumps killed. , Thesis (MSc) -- Faculty of Science, School of Natural Resource Management, 2021
- Full Text:
- Date Issued: 2021-12
- Authors: Mavhungu, Tshilidzi
- Date: 2021-12
- Subjects: Port Elizabeth (South Africa) , Eastern Cape (South Africa) , South Africa
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10948/53857 , vital:46023
- Description: The South Africa (SA) forest industry relies on plantations of exotic forestry trees (Pinus, Acacia and Eucalyptus) to fulfil its timber requirements. With 52.0% of the afforested land in South Africa planted to various eucalypts and their hybrid combinations. Of the total area planted to eucalypts in SA, 75 000 ha is re-established annually by means of silvicultural regimes and operations matched to site productivity, desired end-product and method of regeneration. Unlike other commercially grown tree species, eucalypt species have the ability to coppice after felling. Coppicing is a common form of regeneration in South African forestry as it allows the plantation owner the option of a second timber rotation without replanting. However, if any factors affecting coppicing are compromised, and the site is to be replanted, then it is important to kill the stumps before replanting as rapid initial growth of the coppice shoots will require earlier control than that associated with normal weeding operations. Over time, various methods of woody plant control have been proposed and tested, with most of these making use of herbicides as opposed to the repeated manual removal of coppice regrowth. Globally, most industries subscribe to standards associated with sustainable production (economic, environmental and social) against which they are measured. Within SA, 80% of the forests are certified though either the Forest Stewardship Council (FSC) or International Standards Organisation (ISO) which recommend the identification and avoidance of ‘highly hazardous’ chemicals; the promotion of ‘non-chemical’ methods for pest management as an element of an integrated pest and vegetation management strategy; and the appropriate use of chemicals that are used. To test the current recommendations for killing eucalypt stumps to include other species, the potential of reducing herbicides used, and the influence of time after application on the survival of eucalypt stumps, two trials were initiated at Entabeni plantation (Venda, Limpopo) and one at Wilgeboom plantation (Bushbuckridge, Mpumalanga) between 2018 and 2020. Extending eucalypt cut-stump control practices: Most of the trial work on killing of eucalypts in SA has been conducted on Eucalyptus grandis, Eucalyptus camaldulensis or Eucalyptus macarthurii, with all grown on shorter pulpwood rotations. To extend current recommendation to include Eucalyptus cloeziana (grown on a longer rotation for poles), a trial was established in 2018 at Entabeni plantation (Limpopo Province) to quantify the interaction between Application method (basal-frill; cut-surface; foliar) and Herbicide (no herbicide applied; Roundup; Garlon; Roundup + Garlon) for the killing of 12 year-old stumps following harvesting. Assessments were carried out at 1, 3 and 6 months following application and included Stump survival, Stump quarter with coppice and Coppice heath. Relative to the control plots (100% survival), all herbicides tested were equally effective, 70–90% of the stumps killed. This study confirms previous research regarding the killing of eucalypt stumps. Roundup, Garlon or a combination of two, when applied according to label recommendations to a stump as a basal-frill or cut-surface application (within 30 minutes of felling) resulted in 70-90% of the stumps killed. , Thesis (MSc) -- Faculty of Science, School of Natural Resource Management, 2021
- Full Text:
- Date Issued: 2021-12
Flash floods prediction in South African urban areas: Jukskei river catchment as case study
- Authors: Mawasha, Tshepo Sylvester
- Date: 2021-04
- Subjects: Gqeberha (South Africa) , Eastern Cape (South Africa) , Geographic information systems
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10948/52059 , vital:43429
- Description: This study explored the change relation of multi-temporal land-use/land-cover (LULC) conditions in order to determine how they contribute to change in surface runoff volumes and peak discharge, in an effort to predict flash flooding within the Jukskei River catchment. The research is divided into three main parts: (1) LULC change modeling, (2) rainfall-runoff modeling, and (3) flash floods prediction. Three multi-temporal satellite images of Landsat-5 MMS (1987), Landsat-5 TM (2001) and Landsat-8 OLI (2015) were used for LULC modeling. The analysis of the LULC model revealed that there is a continuous increment in built-up area, from 37.7% to 56.2%, in the expense of other LULC classes for the 28-years preceding this study (i.e., 1987 to 2015). Rainfall-runoff model output results revealed that, for these 28 years, there has been an increase in surface runoff due to change in LULC by 21.5%, 32.9% and 45.5% for 1987, 2001 and 2015, respectively. Due to an increase in surface runoff volume and impervious surface over time, the analysis of HEC-RAS/GeoRAS showed that floodplain extent, flood depth, flood velocity, depth-velocity and the level of damage increases especially in low elevation areas and areas at closed proximity to the Jukskei River. Thus, the building structures and infrastructures are at risk of being affected by flash floods during the rainy season. The findings of this study are expected to be used as basic data for the identification of causative factors of flash floods, areas that generate high surface runoff volume, and the prediction of flash floods within the catchment in future. The flood damage maps developed in this study will be useful to policy-makers and the relevant authorities, as well as to local residents, in finding suitable measures for residential development along the floodplain while reducing flood risk in the study area. , Thesis (PhD) -- Faculty of Science, School of Environmental Sciences, 2021
- Full Text: false
- Date Issued: 2021-04
- Authors: Mawasha, Tshepo Sylvester
- Date: 2021-04
- Subjects: Gqeberha (South Africa) , Eastern Cape (South Africa) , Geographic information systems
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10948/52059 , vital:43429
- Description: This study explored the change relation of multi-temporal land-use/land-cover (LULC) conditions in order to determine how they contribute to change in surface runoff volumes and peak discharge, in an effort to predict flash flooding within the Jukskei River catchment. The research is divided into three main parts: (1) LULC change modeling, (2) rainfall-runoff modeling, and (3) flash floods prediction. Three multi-temporal satellite images of Landsat-5 MMS (1987), Landsat-5 TM (2001) and Landsat-8 OLI (2015) were used for LULC modeling. The analysis of the LULC model revealed that there is a continuous increment in built-up area, from 37.7% to 56.2%, in the expense of other LULC classes for the 28-years preceding this study (i.e., 1987 to 2015). Rainfall-runoff model output results revealed that, for these 28 years, there has been an increase in surface runoff due to change in LULC by 21.5%, 32.9% and 45.5% for 1987, 2001 and 2015, respectively. Due to an increase in surface runoff volume and impervious surface over time, the analysis of HEC-RAS/GeoRAS showed that floodplain extent, flood depth, flood velocity, depth-velocity and the level of damage increases especially in low elevation areas and areas at closed proximity to the Jukskei River. Thus, the building structures and infrastructures are at risk of being affected by flash floods during the rainy season. The findings of this study are expected to be used as basic data for the identification of causative factors of flash floods, areas that generate high surface runoff volume, and the prediction of flash floods within the catchment in future. The flood damage maps developed in this study will be useful to policy-makers and the relevant authorities, as well as to local residents, in finding suitable measures for residential development along the floodplain while reducing flood risk in the study area. , Thesis (PhD) -- Faculty of Science, School of Environmental Sciences, 2021
- Full Text: false
- Date Issued: 2021-04
The synthesis, empirical and theoretical studies of various (N→B) diarylborinate esters
- Authors: Manana, Pholani Sakhile
- Date: 2021-12
- Subjects: Port Elizabeth (South Africa) , Eastern Cape (South Africa) , South Africa
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10948/53869 , vital:46027
- Description: A series of core-functionalized borinic acids was synthesized from Grignard reagents and tributylborate and reacted with ethanolamine, amino acids, 2-pyridylmethanol as well as 2-(ethyl amino ethanol). Among the borinic acids synthesized were the ones bearing: para-(2, 15, 16, 22, 27)-methyl, (3, 20, 25)-chloro, (4, 23, 26)-fluoro, (5)-methoxy; meta-(7, 17)-methyl, (9)-fluoro; ortho-(6)-methyl, (8)-chloro, (10, 18, 19)-methoxy substituents on their respective aromatic systems. All compounds obtained by condensation of the borinic acids with the aforementioned nitrogen-containing substrates were characterized structurally by means of diffraction studies based on single crystals and found to constitute chelate esters/amides featuring covalent B-O and dative N→B bonds. The chelate compounds researched in this study could be classified into four families and represent the compounds: ethanol amine: (1) 2,2-diphenyl-1,3,2-oxazaborolidines, (2) 2,2-bis(p-tolyl)-1,3,2-oxazaborolidines, (3) 2,2-bis(p-chlorophenyl)-1,3,2-oxazaborolidines, (4) 2,2-bis(p-fluorophenyl)-1,3,2-oxazaborolidines, (5) 2,2-bis(p-methoxyphenyl)-1,3,2-oxazaborolidines, (6) 2,2-bis(o-tolyl)-1,3,2-oxazaborolidines, (7) 2,2-bis(m-tolyl)-1,3,2-oxazaborolidines, (8) 2,2-bis(o-chlorophenyl)-1,3,2-oxazaborolidines, (9) 2,2-bis(m-fluorophenyl)-1,3,2-oxazaborolidines, (10) 2,2-bis(o-methoxyphenyl)-1,3,2-oxazaborolidines. α-amino acids : (14) 4-methyl-2,2-diphenyl-1,3,2-oxazaborolidin-5-ones, (15) 2,2-bis(p-tolyl)-1,3,2-oxazaborolidin-5-ones, (16) 4-methyl-2,2-bis(p-tolyl)-1,3,2-oxazaborolidin-5-ones, (17) 4-isopropyl-2,2-bis(m-tolyl)-1,3,2-oxazaborolidin-5-ones, (18) 4-methyl-2,2-bis(o-methoxyphenyl)-1,3,2- oxazaborolidin-5-ones, (19) 4-acetamidyl-2,2-bis(o-methoxyphenyl)-1,3,2- oxazaborolidin-5-ones, (20) 4-phenylethane-2,2-bis(p-chlorophenyl)-1,3,2 oxazaborolidin-5-ones. 2-pyridylmethanol: (21) 1,3-hydroxypyridyl-2,2-diphenyl 1,3,2-oxazaborolidines, (22) 1,3-hydroxypyridyl-2,2-bis(p-tolyl)-1,3,2-oxazaborolidines, (23) 1,3-hydroxypyridyl-2,2-bis(p-fluorophenyl)-1,3,2-oxazaborolidines 2-(ethyl amino ethanol): (24) 3-ethyl-2,2-diphenyl-1,3,2-oxazaborolidines, (25) 3-ethyl-2,2-bis(p-chlorophenyl)-1,3,2-oxazaborolidines, (26) 3-ethyl-2,2-bis(p-fluorophenyl)-1,3,2-oxazaborolidines, (27) 3-ethyl-2,2-bis(p-tolyl)-1,3,2-oxazaborolidines. Apart from structural studies in the solid state, the compounds were also characterized by means of multinuclear NMR spectroscopy (1H, 11B, 13C) as well as UV/vis and FTIR. The typical 11B resonances were found in the range of (4-10 ppm). A series of characteristic metrical parameters for the compounds in the solid state as well as typical NMR shifts for the chelate target molecules was established that allowed for the determination of the coordination induced shift. The carbon atom bonded to the oxygen atom shifted upfield, while the carbon atom bonded to the nitrogen atom shifted downfield. Factors mentioned in the literature that has an influence on the hydrolytic stability on the heterocyclic borinate motif have been taken into consideration and verified for the systems researched in this study. The substitution at the nitrogen atom with one ethyl group caused the greatest increases in the N→B bond length (27) 1.714 Å, due to the increase in the nitrogen Lewis basicity, making it the least hydrolytically stable, these include compounds (24-26). Furthermore, DFT calculations were performed by employing Becke’s three parameter hybrid exchange functional with Lee–Yang–Parr functional (B3LYP) method using the Gaussian 16 program package (Rev. B01) employing the basis set 6-311++G(d,p), to corroborate and correlate the experimental findings, which gave a general R-squared value of 0.9978 for calculated vs experimental 13C chemical shifts. Thermal properties are recorded for select compounds, indicating the ΔH and the melting points. , Thesis (PhD) -- Faculty of Science, School of Biomolecular and Chemical Sciences, 2021
- Full Text:
- Date Issued: 2021-12
- Authors: Manana, Pholani Sakhile
- Date: 2021-12
- Subjects: Port Elizabeth (South Africa) , Eastern Cape (South Africa) , South Africa
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10948/53869 , vital:46027
- Description: A series of core-functionalized borinic acids was synthesized from Grignard reagents and tributylborate and reacted with ethanolamine, amino acids, 2-pyridylmethanol as well as 2-(ethyl amino ethanol). Among the borinic acids synthesized were the ones bearing: para-(2, 15, 16, 22, 27)-methyl, (3, 20, 25)-chloro, (4, 23, 26)-fluoro, (5)-methoxy; meta-(7, 17)-methyl, (9)-fluoro; ortho-(6)-methyl, (8)-chloro, (10, 18, 19)-methoxy substituents on their respective aromatic systems. All compounds obtained by condensation of the borinic acids with the aforementioned nitrogen-containing substrates were characterized structurally by means of diffraction studies based on single crystals and found to constitute chelate esters/amides featuring covalent B-O and dative N→B bonds. The chelate compounds researched in this study could be classified into four families and represent the compounds: ethanol amine: (1) 2,2-diphenyl-1,3,2-oxazaborolidines, (2) 2,2-bis(p-tolyl)-1,3,2-oxazaborolidines, (3) 2,2-bis(p-chlorophenyl)-1,3,2-oxazaborolidines, (4) 2,2-bis(p-fluorophenyl)-1,3,2-oxazaborolidines, (5) 2,2-bis(p-methoxyphenyl)-1,3,2-oxazaborolidines, (6) 2,2-bis(o-tolyl)-1,3,2-oxazaborolidines, (7) 2,2-bis(m-tolyl)-1,3,2-oxazaborolidines, (8) 2,2-bis(o-chlorophenyl)-1,3,2-oxazaborolidines, (9) 2,2-bis(m-fluorophenyl)-1,3,2-oxazaborolidines, (10) 2,2-bis(o-methoxyphenyl)-1,3,2-oxazaborolidines. α-amino acids : (14) 4-methyl-2,2-diphenyl-1,3,2-oxazaborolidin-5-ones, (15) 2,2-bis(p-tolyl)-1,3,2-oxazaborolidin-5-ones, (16) 4-methyl-2,2-bis(p-tolyl)-1,3,2-oxazaborolidin-5-ones, (17) 4-isopropyl-2,2-bis(m-tolyl)-1,3,2-oxazaborolidin-5-ones, (18) 4-methyl-2,2-bis(o-methoxyphenyl)-1,3,2- oxazaborolidin-5-ones, (19) 4-acetamidyl-2,2-bis(o-methoxyphenyl)-1,3,2- oxazaborolidin-5-ones, (20) 4-phenylethane-2,2-bis(p-chlorophenyl)-1,3,2 oxazaborolidin-5-ones. 2-pyridylmethanol: (21) 1,3-hydroxypyridyl-2,2-diphenyl 1,3,2-oxazaborolidines, (22) 1,3-hydroxypyridyl-2,2-bis(p-tolyl)-1,3,2-oxazaborolidines, (23) 1,3-hydroxypyridyl-2,2-bis(p-fluorophenyl)-1,3,2-oxazaborolidines 2-(ethyl amino ethanol): (24) 3-ethyl-2,2-diphenyl-1,3,2-oxazaborolidines, (25) 3-ethyl-2,2-bis(p-chlorophenyl)-1,3,2-oxazaborolidines, (26) 3-ethyl-2,2-bis(p-fluorophenyl)-1,3,2-oxazaborolidines, (27) 3-ethyl-2,2-bis(p-tolyl)-1,3,2-oxazaborolidines. Apart from structural studies in the solid state, the compounds were also characterized by means of multinuclear NMR spectroscopy (1H, 11B, 13C) as well as UV/vis and FTIR. The typical 11B resonances were found in the range of (4-10 ppm). A series of characteristic metrical parameters for the compounds in the solid state as well as typical NMR shifts for the chelate target molecules was established that allowed for the determination of the coordination induced shift. The carbon atom bonded to the oxygen atom shifted upfield, while the carbon atom bonded to the nitrogen atom shifted downfield. Factors mentioned in the literature that has an influence on the hydrolytic stability on the heterocyclic borinate motif have been taken into consideration and verified for the systems researched in this study. The substitution at the nitrogen atom with one ethyl group caused the greatest increases in the N→B bond length (27) 1.714 Å, due to the increase in the nitrogen Lewis basicity, making it the least hydrolytically stable, these include compounds (24-26). Furthermore, DFT calculations were performed by employing Becke’s three parameter hybrid exchange functional with Lee–Yang–Parr functional (B3LYP) method using the Gaussian 16 program package (Rev. B01) employing the basis set 6-311++G(d,p), to corroborate and correlate the experimental findings, which gave a general R-squared value of 0.9978 for calculated vs experimental 13C chemical shifts. Thermal properties are recorded for select compounds, indicating the ΔH and the melting points. , Thesis (PhD) -- Faculty of Science, School of Biomolecular and Chemical Sciences, 2021
- Full Text:
- Date Issued: 2021-12
Applying a systems analysis approach to support marine spatial planning in Algoa Bay, South Africa
- Authors: Vermeulen, Estee Ann
- Date: 2021-12
- Subjects: Port Elizabeth (South Africa) , Eastern Cape (South Africa) , South Africa
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10948/54121 , vital:46312
- Description: Ocean health provides the foundation for human health through the provisioning of ecosystem services. Increasing demands on ocean space and resources are, however, resulting in a decline in ocean health, with direct and indirect knock-on effects on marine uses and ultimately on human health. In response, there is a growing need to acknowledge and better manage complex human-ocean interactions. This has been recognised in global sustainable development goals and in integrated ocean management processes, leading to widespread endorsement of an ecosystem-based marine spatial planning (MSP) process, including in South Africa. In support of the national MSP process, significant progress has been made in understanding the spatial extent of marine activities and associated marine pressures, but the temporal dynamics of marine activities and interconnections with the marine environment are less well understood. To plan for the growth of marine activities and associated user conflicts, the drivers of these temporal dynamics and associated feedback effects need to be analysed and potential policy and management interventions identified and tested. To support South Africa’s national MSP process, this study adopts a systems analysis approach, using system dynamics modelling, to explore the temporal change in marine uses under alternative growth scenarios in Algoa Bay. Algoa Bay is an appropriate study area because it is experiencing a rapid expansion of marine activities, coupled with a growing uncertainty regarding marine sustainability outcomes. To assist future marine management decisions, the Algoa Marine Systems Analysis Tool (Algoa MSAT) was developed, comprising seven sub-models. Five of the sub-models represent selected marine uses in Algoa Bay, whereas the sixth and seventh integrate the outputs from each marine use in terms of sustainable management indicators (marine health, marine wealth and marine labour). Model development primarily adopted an expert-based model ling approach, although the involvement of stakeholders, through a collaborative modelling process, assisted in integrating knowledge on different marine sectors’ activities, impacts and planning visions into the model framework. Model results were generated under different scenarios to investigate changes in the growth of marine activities and marine sustainability indicators under different levels of ocean governance. Under the baseline (or business-as-usual) model scenario, marine activities were shown to grow increasingly within their respective management limits, with an increase in marine wealth and labour and a consequential decrease in marine health. This scenario particularly highlights that current ocean governance practices are ineffective in sustaining the projected growth of the marine uses, particularly for those that are vulnerable to negative changes in marine health. Conversely, sectors that hold more value in marine wealth and are more resilient to changes in marine health, may continue to grow regardless of negative knock-on effects of the health of the marine environment and on other uses in the bay. This emphasises that an alternative governance strategy is needed to achieve the long-term goal of an ecosystem-based MSP process, as required by South African MSP legislation. To achieve this will require multiple, adaptive cross-sectoral management interventions that are directed towards the ‘deeper leverage points’ that are able to maintain the growth of marine activities within appropriate limits defined by marine health. Using the model interface developed in this project, decision-makers and stakeholders can use the model to explore the temporal dynamics in marine activities under different governance scenarios. Although the model is limited to Algoa Bay, the model boundary can be adapted to assist in marine planning processes at national or trans-national scales. Such analytical assessments and tools are critical to progress the ecosystem-based management approach in MSP, as is required to achieve global sustainable development goals. , Thesis (PhD) -- Faculty of Science, Coastal and Marine Research Unit, 2021
- Full Text:
- Date Issued: 2021-12
- Authors: Vermeulen, Estee Ann
- Date: 2021-12
- Subjects: Port Elizabeth (South Africa) , Eastern Cape (South Africa) , South Africa
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10948/54121 , vital:46312
- Description: Ocean health provides the foundation for human health through the provisioning of ecosystem services. Increasing demands on ocean space and resources are, however, resulting in a decline in ocean health, with direct and indirect knock-on effects on marine uses and ultimately on human health. In response, there is a growing need to acknowledge and better manage complex human-ocean interactions. This has been recognised in global sustainable development goals and in integrated ocean management processes, leading to widespread endorsement of an ecosystem-based marine spatial planning (MSP) process, including in South Africa. In support of the national MSP process, significant progress has been made in understanding the spatial extent of marine activities and associated marine pressures, but the temporal dynamics of marine activities and interconnections with the marine environment are less well understood. To plan for the growth of marine activities and associated user conflicts, the drivers of these temporal dynamics and associated feedback effects need to be analysed and potential policy and management interventions identified and tested. To support South Africa’s national MSP process, this study adopts a systems analysis approach, using system dynamics modelling, to explore the temporal change in marine uses under alternative growth scenarios in Algoa Bay. Algoa Bay is an appropriate study area because it is experiencing a rapid expansion of marine activities, coupled with a growing uncertainty regarding marine sustainability outcomes. To assist future marine management decisions, the Algoa Marine Systems Analysis Tool (Algoa MSAT) was developed, comprising seven sub-models. Five of the sub-models represent selected marine uses in Algoa Bay, whereas the sixth and seventh integrate the outputs from each marine use in terms of sustainable management indicators (marine health, marine wealth and marine labour). Model development primarily adopted an expert-based model ling approach, although the involvement of stakeholders, through a collaborative modelling process, assisted in integrating knowledge on different marine sectors’ activities, impacts and planning visions into the model framework. Model results were generated under different scenarios to investigate changes in the growth of marine activities and marine sustainability indicators under different levels of ocean governance. Under the baseline (or business-as-usual) model scenario, marine activities were shown to grow increasingly within their respective management limits, with an increase in marine wealth and labour and a consequential decrease in marine health. This scenario particularly highlights that current ocean governance practices are ineffective in sustaining the projected growth of the marine uses, particularly for those that are vulnerable to negative changes in marine health. Conversely, sectors that hold more value in marine wealth and are more resilient to changes in marine health, may continue to grow regardless of negative knock-on effects of the health of the marine environment and on other uses in the bay. This emphasises that an alternative governance strategy is needed to achieve the long-term goal of an ecosystem-based MSP process, as required by South African MSP legislation. To achieve this will require multiple, adaptive cross-sectoral management interventions that are directed towards the ‘deeper leverage points’ that are able to maintain the growth of marine activities within appropriate limits defined by marine health. Using the model interface developed in this project, decision-makers and stakeholders can use the model to explore the temporal dynamics in marine activities under different governance scenarios. Although the model is limited to Algoa Bay, the model boundary can be adapted to assist in marine planning processes at national or trans-national scales. Such analytical assessments and tools are critical to progress the ecosystem-based management approach in MSP, as is required to achieve global sustainable development goals. , Thesis (PhD) -- Faculty of Science, Coastal and Marine Research Unit, 2021
- Full Text:
- Date Issued: 2021-12
The synthesis of anastrazole intermediates using continuous flow systems
- Authors: Tanyi, Sam Tambi
- Date: 2021-12
- Subjects: Port Elizabeth (South Africa) , Eastern Cape (South Africa) , South Africa
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10948/54116 , vital:46304
- Description: In this study, the continuous flow synthesis of anastrozole intermediates were investigated using mesitylene as starting material. Anastrozole is an important drug used for the treatment of breast cancer. In the first step, mesitylene was brominated using N-bromosuccinimide to obtain 3,5-bis(bromomethyl)toluene. Selectivity became an issue due to the formation of two by-products; namely 1,3,5-tris(bromomethyl) benzene (the tribrominated by-product) and 1-(bromomethyl)-3,5-dimethylbenzene (the monobrominated by-product). Since the reaction parameters can be more precisely controlled in flow chemistry systems, we were able to optimize the formation the desired product 3,5-bis(bromomethyl)toluene. The reaction was initially optimized ina 15μLChemtrix glass micro reactor resulting in 100%conversion with 95%selectivity towards the desired product 3,5-bis(bromomethyl)toluenein 15 seconds, with a throughput of 0.006 g/h. The reaction was then scaled up in a 1.7 mLLTF reactor, equally yielding 100%conversion with 95%selectivityin 4minutes, with a throughput of2.01g/h. The bromination of mesitylene was also attempted in a homemade photochemical reactor consisting of a 3.02 polytetrafluoroethylene coil reactor and BLE-6T365 UV lamp. In this photochemical reactor, although 100%conversionwas again obtained only75%selectivity was achieved in 20minutes, with a throughput of 0.025g/h. This drop in selectivity was attributed to poorer mixing in the larger polytetrafluoroethylene coil reactor and possibly insufficient light penetration. The next step, involving the cyanation of 3,5-bis(bromomethyl)toluene to obtain 2,2'-(5-methyl-1,3-phenylene) diacetonitrilegave 100%conversion in 1 minute at 190 °C in a 1.7 mLLTFreactor, with a throughput of 5.2g/h. The subsequent methylation of 3,5-bis(cyanomethyl)toluene to obtain3,5-bis(1-cyano-1-methylethyl) toluene was investigated using a1mLpolytetrafluoroethylenecoil reactor, ultimatelyachieving99%conversionat40 °Cin 8minutes, with a throughput of 0.045g/h. Next, the bromination of3,5-bis(1-cyano-1-methylethyl)toluene using N-bromosuccinimideto yield 2,2'-(5-bromomethyl-1,3-phenylene)di(2-methyl propionitrile) gave 100%conversion at 120 °C in 4 minutes, with a throughput of 0.35g/h. Lastly, the multistep synthesis of 3,5-bis(cyanomethyl)toluene was done in two integrated 1.7 mLLTF reactors, using the predetermined optimum conditions to achieve 94%conversion towards 3,5-bis(cyanomethyl)toluene with a total r , Thesis (MSc) -- Faculty of Science, School of Biomolecular and Chemical Sciences, 2021
- Full Text:
- Date Issued: 2021-12
- Authors: Tanyi, Sam Tambi
- Date: 2021-12
- Subjects: Port Elizabeth (South Africa) , Eastern Cape (South Africa) , South Africa
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10948/54116 , vital:46304
- Description: In this study, the continuous flow synthesis of anastrozole intermediates were investigated using mesitylene as starting material. Anastrozole is an important drug used for the treatment of breast cancer. In the first step, mesitylene was brominated using N-bromosuccinimide to obtain 3,5-bis(bromomethyl)toluene. Selectivity became an issue due to the formation of two by-products; namely 1,3,5-tris(bromomethyl) benzene (the tribrominated by-product) and 1-(bromomethyl)-3,5-dimethylbenzene (the monobrominated by-product). Since the reaction parameters can be more precisely controlled in flow chemistry systems, we were able to optimize the formation the desired product 3,5-bis(bromomethyl)toluene. The reaction was initially optimized ina 15μLChemtrix glass micro reactor resulting in 100%conversion with 95%selectivity towards the desired product 3,5-bis(bromomethyl)toluenein 15 seconds, with a throughput of 0.006 g/h. The reaction was then scaled up in a 1.7 mLLTF reactor, equally yielding 100%conversion with 95%selectivityin 4minutes, with a throughput of2.01g/h. The bromination of mesitylene was also attempted in a homemade photochemical reactor consisting of a 3.02 polytetrafluoroethylene coil reactor and BLE-6T365 UV lamp. In this photochemical reactor, although 100%conversionwas again obtained only75%selectivity was achieved in 20minutes, with a throughput of 0.025g/h. This drop in selectivity was attributed to poorer mixing in the larger polytetrafluoroethylene coil reactor and possibly insufficient light penetration. The next step, involving the cyanation of 3,5-bis(bromomethyl)toluene to obtain 2,2'-(5-methyl-1,3-phenylene) diacetonitrilegave 100%conversion in 1 minute at 190 °C in a 1.7 mLLTFreactor, with a throughput of 5.2g/h. The subsequent methylation of 3,5-bis(cyanomethyl)toluene to obtain3,5-bis(1-cyano-1-methylethyl) toluene was investigated using a1mLpolytetrafluoroethylenecoil reactor, ultimatelyachieving99%conversionat40 °Cin 8minutes, with a throughput of 0.045g/h. Next, the bromination of3,5-bis(1-cyano-1-methylethyl)toluene using N-bromosuccinimideto yield 2,2'-(5-bromomethyl-1,3-phenylene)di(2-methyl propionitrile) gave 100%conversion at 120 °C in 4 minutes, with a throughput of 0.35g/h. Lastly, the multistep synthesis of 3,5-bis(cyanomethyl)toluene was done in two integrated 1.7 mLLTF reactors, using the predetermined optimum conditions to achieve 94%conversion towards 3,5-bis(cyanomethyl)toluene with a total r , Thesis (MSc) -- Faculty of Science, School of Biomolecular and Chemical Sciences, 2021
- Full Text:
- Date Issued: 2021-12
Upwelling over submarine canyons: an in-situ and modelling approach
- Authors: Rautenbach, Gustav
- Date: 2021-04
- Subjects: Gqeberha (South Africa) , Eastern Cape (South Africa) , Oceanography -- Research -- South Africa
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10948/52078 , vital:43442
- Description: The iSimangaliso Wetland Park, located along the coastline of northern KwaZulu-Natal (KZN), hosts South Africa's only tropical coral reef system and is clustered with submarine canyons. These ecosystems support a flourishing diving and pelagic sportfishing industry in the area that contributes tens of millions of rand to the South African Gross Domestic Profit (GDP) annually as well as to provide income and job security for the majority of the local residents. Understanding the oceanographic dynamics, particularly upwelling events, will improve current knowledge of how the ecosystem works and may enhance conservation techniques. The upwelling events within the iSimangaliso Wetland Park results in the influx of cold and nutrient rich waters that supports biological productivity in the area. The complex oceanography, dominated by the Northern Agulhas Current and mesoscale eddies that stem from the Mozambique Channel and South East Madagascar Current (SEMC) is understudied and lacks understanding. This thesis aims to build upon the current knowledge of the upwelling events over the submarine canyons and the concurrent influence on the Mixed Layer Depth (MLD). At the submarine canyons, six anomalous cooling events were identified from surface and subsurface measurements extracted from the Operational Sea Surface Temperature and Ice Analysis (OSTIA) Sea Surface Temperature (SST) and from data collected using Underwater Temperature Recorders (UTRs) over a 12-month period. Depth-integrated lagged correlations showed a 2-to-7-hour lag period from the deep to shallow stations, suggesting that the anomalous cooling events are in fact upwelling events. Wind measurements from the Mbazwana Weather Station and snapshots of sea-level anomalies illustrated that the weaker and shorter upwelling events are driven either by alongshore wind stress or a cyclonic eddy event solely; whereas the stronger event was driven by the combination of both forcing mechanisms. An idealized canyon ocean model is used to interrogate the two forcing mechanisms more fully and showed that the most intense upwelling events are driven by the combined effect of upwelling-favourable alongshore wind stress and a cyclonic eddy which results in strong upward vertical velocity anomalies and the greatest shallowing (6.88 m) of the MLD. With the contribution of the in-situ measurements as a baseline study it is apparent that the idealised model does provide an improved understanding of the upwelling events and forcing mechanism over the submarine canyons within the iSimangaliso Wetland Park. , Thesis (MSc) -- Faculty of Science, Ocean Sciences, 2021
- Full Text: false
- Date Issued: 2021-04
- Authors: Rautenbach, Gustav
- Date: 2021-04
- Subjects: Gqeberha (South Africa) , Eastern Cape (South Africa) , Oceanography -- Research -- South Africa
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10948/52078 , vital:43442
- Description: The iSimangaliso Wetland Park, located along the coastline of northern KwaZulu-Natal (KZN), hosts South Africa's only tropical coral reef system and is clustered with submarine canyons. These ecosystems support a flourishing diving and pelagic sportfishing industry in the area that contributes tens of millions of rand to the South African Gross Domestic Profit (GDP) annually as well as to provide income and job security for the majority of the local residents. Understanding the oceanographic dynamics, particularly upwelling events, will improve current knowledge of how the ecosystem works and may enhance conservation techniques. The upwelling events within the iSimangaliso Wetland Park results in the influx of cold and nutrient rich waters that supports biological productivity in the area. The complex oceanography, dominated by the Northern Agulhas Current and mesoscale eddies that stem from the Mozambique Channel and South East Madagascar Current (SEMC) is understudied and lacks understanding. This thesis aims to build upon the current knowledge of the upwelling events over the submarine canyons and the concurrent influence on the Mixed Layer Depth (MLD). At the submarine canyons, six anomalous cooling events were identified from surface and subsurface measurements extracted from the Operational Sea Surface Temperature and Ice Analysis (OSTIA) Sea Surface Temperature (SST) and from data collected using Underwater Temperature Recorders (UTRs) over a 12-month period. Depth-integrated lagged correlations showed a 2-to-7-hour lag period from the deep to shallow stations, suggesting that the anomalous cooling events are in fact upwelling events. Wind measurements from the Mbazwana Weather Station and snapshots of sea-level anomalies illustrated that the weaker and shorter upwelling events are driven either by alongshore wind stress or a cyclonic eddy event solely; whereas the stronger event was driven by the combination of both forcing mechanisms. An idealized canyon ocean model is used to interrogate the two forcing mechanisms more fully and showed that the most intense upwelling events are driven by the combined effect of upwelling-favourable alongshore wind stress and a cyclonic eddy which results in strong upward vertical velocity anomalies and the greatest shallowing (6.88 m) of the MLD. With the contribution of the in-situ measurements as a baseline study it is apparent that the idealised model does provide an improved understanding of the upwelling events and forcing mechanism over the submarine canyons within the iSimangaliso Wetland Park. , Thesis (MSc) -- Faculty of Science, Ocean Sciences, 2021
- Full Text: false
- Date Issued: 2021-04
Microstructural characterization of Swift Heavy Ion (SHI) induced rotation in single crystal NiO
- Authors: Douglas-Henry, Danielle
- Date: 2021-12
- Subjects: Port Elizabeth (South Africa) , Eastern Cape (South Africa) , South Africa
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10948/53648 , vital:45685
- Description: Swift Heavy Ions (SHI) are characterised by having energies greater than 1 MeV per nucleon with an atomic mass greater than 6 amu. Exposure to irradiation of this type has been known to produce latent tracks in insulators. This is due to the energy loss through the material being governed by electronic excitation processes. The extent of the track formation and microstructural changes induced has been reported to be material specific. Models such as the thermal spike model have been used to explain these changes, however rough approximations are still made. A particularly under studied phenomena is the collective rotation seen in materials exposed to off-normal incidence irradiation. To date the only available experimental data is X-Ray Diffraction (XRD) spectra and surface shifts. This does not allow for depth-dependent rotation studies and very little can be deduced regarding the microstructure of the modified volume. In this study, the microstructural changes in single crystal Nickel Oxide (NiO) have been studied using electron microscopy techniques. A depth dependent investigation of the crystal rotation was performed using Selected Area Electron Diffraction (SAED), Transmission Kikuchi Diffraction (TKD) and Electron Backscatter Diffraction (EBSD). Transmission Electron Microscopy (TEM) and Scanning Transmission Electron Microscopy (STEM) were utilized to interrogate the microstructural changes facilitating the bulk rotation. Five different NiO specimens were investigated. Specimens had surfaces parallel to either the {0 0 1} or {1 1 1} planes. Ion energies used were 593 MeV, 940 MeV and 1.6 GeV, while fluences ranged from 1.0 x 1011 ions/cm² to 9.6 x 1014 ions/cm². Latent track formation in both low fluence (nonoverlapping regime) and high fluence (overlapping regime) specimens were investigated and compared. , Thesis (PhD) -- Faculty of Science, School of Computer Science, Mathematics, Physics and Statistics, 2021
- Full Text: false
- Date Issued: 2021-12
- Authors: Douglas-Henry, Danielle
- Date: 2021-12
- Subjects: Port Elizabeth (South Africa) , Eastern Cape (South Africa) , South Africa
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10948/53648 , vital:45685
- Description: Swift Heavy Ions (SHI) are characterised by having energies greater than 1 MeV per nucleon with an atomic mass greater than 6 amu. Exposure to irradiation of this type has been known to produce latent tracks in insulators. This is due to the energy loss through the material being governed by electronic excitation processes. The extent of the track formation and microstructural changes induced has been reported to be material specific. Models such as the thermal spike model have been used to explain these changes, however rough approximations are still made. A particularly under studied phenomena is the collective rotation seen in materials exposed to off-normal incidence irradiation. To date the only available experimental data is X-Ray Diffraction (XRD) spectra and surface shifts. This does not allow for depth-dependent rotation studies and very little can be deduced regarding the microstructure of the modified volume. In this study, the microstructural changes in single crystal Nickel Oxide (NiO) have been studied using electron microscopy techniques. A depth dependent investigation of the crystal rotation was performed using Selected Area Electron Diffraction (SAED), Transmission Kikuchi Diffraction (TKD) and Electron Backscatter Diffraction (EBSD). Transmission Electron Microscopy (TEM) and Scanning Transmission Electron Microscopy (STEM) were utilized to interrogate the microstructural changes facilitating the bulk rotation. Five different NiO specimens were investigated. Specimens had surfaces parallel to either the {0 0 1} or {1 1 1} planes. Ion energies used were 593 MeV, 940 MeV and 1.6 GeV, while fluences ranged from 1.0 x 1011 ions/cm² to 9.6 x 1014 ions/cm². Latent track formation in both low fluence (nonoverlapping regime) and high fluence (overlapping regime) specimens were investigated and compared. , Thesis (PhD) -- Faculty of Science, School of Computer Science, Mathematics, Physics and Statistics, 2021
- Full Text: false
- Date Issued: 2021-12
Cluster analysis for group selection in launch sales predictions
- Authors: Watchurst, Lee
- Date: 2021-04
- Subjects: Gqeberha (South Africa) , Eastern Cape (South Africa) , Cluster analysis
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10948/52003 , vital:43447
- Description: One way for businesses to stay ahead in a competitive market is through the launch of new products and planning for these launches optimally. This includes ordering the correct quantity of stock in advance as well as maintaining these stock levels while the item launches. However, holding too much stock in warehouses can affect the business costs adversely. This research proposes the use of cluster analysis techniques to determine the up-front purchase quantity by identifying similar items and using their initial quantities sold. Products will be grouped based on their numerical and categorical attributes. Once the data is clustered, the Bass model will be used to obtain a sales profile for the new item. The Bass model is a popular choice for product life cycle planning due to the emphasis placed on the timing of adoption. The study will make use of data from a retail and wholesale company that sells, in part, single use items. With the planning for new launches being a key problem point in many companies, this research aims to optimise the planning process and ensure product launch success across stores. , Thesis (MSc) -- Faculty of Science, School of Computer Science, Mathematics, Physics and Statistics, 2021
- Full Text: false
- Date Issued: 2021-04
- Authors: Watchurst, Lee
- Date: 2021-04
- Subjects: Gqeberha (South Africa) , Eastern Cape (South Africa) , Cluster analysis
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10948/52003 , vital:43447
- Description: One way for businesses to stay ahead in a competitive market is through the launch of new products and planning for these launches optimally. This includes ordering the correct quantity of stock in advance as well as maintaining these stock levels while the item launches. However, holding too much stock in warehouses can affect the business costs adversely. This research proposes the use of cluster analysis techniques to determine the up-front purchase quantity by identifying similar items and using their initial quantities sold. Products will be grouped based on their numerical and categorical attributes. Once the data is clustered, the Bass model will be used to obtain a sales profile for the new item. The Bass model is a popular choice for product life cycle planning due to the emphasis placed on the timing of adoption. The study will make use of data from a retail and wholesale company that sells, in part, single use items. With the planning for new launches being a key problem point in many companies, this research aims to optimise the planning process and ensure product launch success across stores. , Thesis (MSc) -- Faculty of Science, School of Computer Science, Mathematics, Physics and Statistics, 2021
- Full Text: false
- Date Issued: 2021-04
Synthesis and characterization of iron doped sodium and potassium titanates using the pechini sol-gel method
- Authors: Guga, Aluwani
- Date: 2021-12
- Subjects: Port Elizabeth (South Africa) , Eastern Cape (South Africa) , South Africa
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10948/53646 , vital:45683
- Description: Iron doped (Fe: 5Ti) sodium and potassium titanates were prepared by the Pechini sol-gel method and calcined at 800 °C. X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy dispersive X-ray spectrometry (EDS), FTIR and Raman spectroscopy were used to characterize the structure and morphology of the titanate nanomaterials. A quantitative XRD analysis using Rietveld refinement of the titanates confirmed the powders to consist of crystalline phases with the Na2Ti7O15 and K2Ti8O17 phases predominant for the sodium and potassium titanate, respectively. This was further confirmed using selected area electron diffraction (SAED) in the TEM. SEM and TEM analyses indicated that the titanates are consistent with a nanostructured material exhibiting rod-like morphology. The elemental compositions of the titanites were examined by SEM-EDS and TEM-EDS and found to agree well with the targeted Fe to Ti ratio from synthesis. Limited evidence for the segregation of iron in the titanate regions were found indicating the iron to be incorporated within the titanate lattice. Electron energy loss spectroscopy (EELS) fine-structure analysis of the Fe L2,3 core-loss edge was successfully used to match the Fe to a 2+ or 3+ valence state, consistent with its occupation at Ti lattice sites. Finally, Fourier transform infrared spectroscopy (FTIR) and Raman spectroscopy were used to study the vibrational modes of the functional group of the sodium and potassium titanates. Vibrational modes consistent with previously reported findings for the titanate phases identified were found with no evidence of isolated Fe related modes. , Thesis (MSc) -- Faculty of Science, Computer Science, Mathematics, Physics and Statistics, 2021
- Full Text: false
- Date Issued: 2021-12
- Authors: Guga, Aluwani
- Date: 2021-12
- Subjects: Port Elizabeth (South Africa) , Eastern Cape (South Africa) , South Africa
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10948/53646 , vital:45683
- Description: Iron doped (Fe: 5Ti) sodium and potassium titanates were prepared by the Pechini sol-gel method and calcined at 800 °C. X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy dispersive X-ray spectrometry (EDS), FTIR and Raman spectroscopy were used to characterize the structure and morphology of the titanate nanomaterials. A quantitative XRD analysis using Rietveld refinement of the titanates confirmed the powders to consist of crystalline phases with the Na2Ti7O15 and K2Ti8O17 phases predominant for the sodium and potassium titanate, respectively. This was further confirmed using selected area electron diffraction (SAED) in the TEM. SEM and TEM analyses indicated that the titanates are consistent with a nanostructured material exhibiting rod-like morphology. The elemental compositions of the titanites were examined by SEM-EDS and TEM-EDS and found to agree well with the targeted Fe to Ti ratio from synthesis. Limited evidence for the segregation of iron in the titanate regions were found indicating the iron to be incorporated within the titanate lattice. Electron energy loss spectroscopy (EELS) fine-structure analysis of the Fe L2,3 core-loss edge was successfully used to match the Fe to a 2+ or 3+ valence state, consistent with its occupation at Ti lattice sites. Finally, Fourier transform infrared spectroscopy (FTIR) and Raman spectroscopy were used to study the vibrational modes of the functional group of the sodium and potassium titanates. Vibrational modes consistent with previously reported findings for the titanate phases identified were found with no evidence of isolated Fe related modes. , Thesis (MSc) -- Faculty of Science, Computer Science, Mathematics, Physics and Statistics, 2021
- Full Text: false
- Date Issued: 2021-12
Participatory mapping of cultural ecosystem services in the Mountain Zebra National Park, South Africa
- Authors: Mpapane, Nelsiwe Pertunia
- Date: 2021-04
- Subjects: Gqeberha (South Africa) , Eastern Cape (South Africa) , Nature--Effect of human beings on--South Africa
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10948/52103 , vital:43432
- Description: Cultural ecosystem services (CES) are an essential part of human well-being. CES characterize the intangible connections that people have with their surrounding environments, and act as vessels to facilitate the understanding of meaningful and respectful relationships between humans and nature, which are necessary for sustainability. However, CES render themselves as complex cultural dimensions that are difficult to connect to specific aspects of an ecosystem, or to measure and manage. Thus, a progressive approach is required for promoting effective management of CES within landscapes. This thesis endeavours to understand human─nature interactions in protected areas, the CES benefits that arise from such interactions, and the links of these to ecosystems, facilities or features within the landscape. Protected areas represent some of the last remaining intact ecological areas that support biodiversity conservation and human─nature experiences. Protected areas, such as the Mountain Zebra National Park, are therefore suitable study sites to cast light on: (a) how human─nature relationships manifest in parks, (b) which CES are experienced by visitors, (c) which landscape features are associated with CES benefits, (d) who visits the Park, and (e) how the delivery and/or accessibility of CES to visitors of the Park could be improved. My research involved qualitative and spatial elements as forms of enquiry over a period of six months of data collection. I used semi-structured interviews (n = 20) paired with a participatory mapping approach. Additionally, I performed a comparative analysis using a peer-reviewed paper that focused on the management perspectives of CES delivery, to seek out similarities and differences between management perspectives and actual visitor experiences. The findings of this study have outlined that the Mountain Zebra National Park offers significant benefits to visitors. Aesthetic, recreational, inspirational value and cultural heritage emerged as the most frequently mapped CES. The findings have also shown that CES benefits are widely distributed across the landscape, with a spatial correlation in hotspot areas. Moreover, amenities or built infrastructure such as picnic iii sites, camping areas and viewpoints within the Park, are crucial for strengthening social relationships among family and friends, as well as in aiding the delivery of CES. This study provides insights into the subjective and diverse ways that human─nature relationships translate into CES benefits. It also sheds light on the importance of adequate planning within protected areas, for the maximization of the benefits from CES to people without compromising the mandate of biodiversity conservation. This study also contributes to a growing body of evidence that documents human─nature interactions in, and non-material benefits acquired from, protected areas within South Africa. I further advocate for improved access, adequate infrastructure, awareness creation and strategies to attract the younger generation to the national parks of South Africa. , Thesis (MSc) -- Faculty of Science, School of Natural Resource Management, 2021
- Full Text: false
- Date Issued: 2021-04
- Authors: Mpapane, Nelsiwe Pertunia
- Date: 2021-04
- Subjects: Gqeberha (South Africa) , Eastern Cape (South Africa) , Nature--Effect of human beings on--South Africa
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10948/52103 , vital:43432
- Description: Cultural ecosystem services (CES) are an essential part of human well-being. CES characterize the intangible connections that people have with their surrounding environments, and act as vessels to facilitate the understanding of meaningful and respectful relationships between humans and nature, which are necessary for sustainability. However, CES render themselves as complex cultural dimensions that are difficult to connect to specific aspects of an ecosystem, or to measure and manage. Thus, a progressive approach is required for promoting effective management of CES within landscapes. This thesis endeavours to understand human─nature interactions in protected areas, the CES benefits that arise from such interactions, and the links of these to ecosystems, facilities or features within the landscape. Protected areas represent some of the last remaining intact ecological areas that support biodiversity conservation and human─nature experiences. Protected areas, such as the Mountain Zebra National Park, are therefore suitable study sites to cast light on: (a) how human─nature relationships manifest in parks, (b) which CES are experienced by visitors, (c) which landscape features are associated with CES benefits, (d) who visits the Park, and (e) how the delivery and/or accessibility of CES to visitors of the Park could be improved. My research involved qualitative and spatial elements as forms of enquiry over a period of six months of data collection. I used semi-structured interviews (n = 20) paired with a participatory mapping approach. Additionally, I performed a comparative analysis using a peer-reviewed paper that focused on the management perspectives of CES delivery, to seek out similarities and differences between management perspectives and actual visitor experiences. The findings of this study have outlined that the Mountain Zebra National Park offers significant benefits to visitors. Aesthetic, recreational, inspirational value and cultural heritage emerged as the most frequently mapped CES. The findings have also shown that CES benefits are widely distributed across the landscape, with a spatial correlation in hotspot areas. Moreover, amenities or built infrastructure such as picnic iii sites, camping areas and viewpoints within the Park, are crucial for strengthening social relationships among family and friends, as well as in aiding the delivery of CES. This study provides insights into the subjective and diverse ways that human─nature relationships translate into CES benefits. It also sheds light on the importance of adequate planning within protected areas, for the maximization of the benefits from CES to people without compromising the mandate of biodiversity conservation. This study also contributes to a growing body of evidence that documents human─nature interactions in, and non-material benefits acquired from, protected areas within South Africa. I further advocate for improved access, adequate infrastructure, awareness creation and strategies to attract the younger generation to the national parks of South Africa. , Thesis (MSc) -- Faculty of Science, School of Natural Resource Management, 2021
- Full Text: false
- Date Issued: 2021-04
The aesthetics of hegemony: a speculative design proposal exploring the convergence of surveillance capitalism and brain-computer interface technologies in the future
- Authors: Davies, James Tibbott
- Date: 2021-12
- Subjects: Port Elizabeth (South Africa) , Eastern Cape (South Africa) , South Africa
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10948/54417 , vital:46517
- Description: This study examines the power dynamics of surveillance capitalism, and its role in shaping cultural hegemony. The research was expressed using graphic design to illustrate a (potential) future where Brain-Computer Interfaces (BCIs) and surveillance capitalism converge. The critique focused on Google and Facebook’s hegemony in the data-surveillance marketplace and what role this has in shaping global discourse. Both companies are funding the development of BCIs, with the aim of using brain signals as a means of interacting with the digital world, which would give the two biggest advertising companies in the world access to new sources of data. A speculative design framework was utilized to visually question the societal implications of this emerging technology and the funding behind its development. A theoretical investigation of the concepts underpinning critical theory and critical design was conducted to help clarify and critically inform this methodological approach, promoting the use of practice-based design as a critically reflective investigative tool. The resulting artefacts designed using this process were showcased in the form of a website and video that act as a visual embodiment the research, demonstrating the efficacy of this approach and the value of using communication design as a mechanism to question the status quo. , Thesis (MA) -- Faculty of Humanities, School of Visual and Performing Arts, 2021
- Full Text:
- Date Issued: 2021-12
- Authors: Davies, James Tibbott
- Date: 2021-12
- Subjects: Port Elizabeth (South Africa) , Eastern Cape (South Africa) , South Africa
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10948/54417 , vital:46517
- Description: This study examines the power dynamics of surveillance capitalism, and its role in shaping cultural hegemony. The research was expressed using graphic design to illustrate a (potential) future where Brain-Computer Interfaces (BCIs) and surveillance capitalism converge. The critique focused on Google and Facebook’s hegemony in the data-surveillance marketplace and what role this has in shaping global discourse. Both companies are funding the development of BCIs, with the aim of using brain signals as a means of interacting with the digital world, which would give the two biggest advertising companies in the world access to new sources of data. A speculative design framework was utilized to visually question the societal implications of this emerging technology and the funding behind its development. A theoretical investigation of the concepts underpinning critical theory and critical design was conducted to help clarify and critically inform this methodological approach, promoting the use of practice-based design as a critically reflective investigative tool. The resulting artefacts designed using this process were showcased in the form of a website and video that act as a visual embodiment the research, demonstrating the efficacy of this approach and the value of using communication design as a mechanism to question the status quo. , Thesis (MA) -- Faculty of Humanities, School of Visual and Performing Arts, 2021
- Full Text:
- Date Issued: 2021-12
A study of the airflow on the windward slope of a transverse dune in the Alexandria coastal dunefield
- Authors: Burkinshaw, Jennifer Ruth
- Date: 2021-04
- Subjects: Port Elizabeth (South Africa) , Eastern Cape (South Africa) , South Africa
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10948/52734 , vital:43883
- Description: Our understanding of the evolution of dune morphology has been hampered by a lack of empirical observations of airflow behaviour over dune forms. Sand dunes intrude into the atmospheric boundary layer and convergence of streamlines results in an acceleration of airflow up the windward slopes of dunes. This study examines the airflow structure and corresponding bedform development on the windward slope of a 7 m high transverse dune on the edge of the Alexandria coastal dunefield, Algoa Bay, South Africa. The Alexandria dunefield is subjected to a trimodal wind regime, consisting of the dominant south-westerly which blows all year round, summer easterlies and winter northwesterlies. The morphology of the study dune, Dune13, is controlled by the easterlies and north-westerlies, and reverses seasonally with respect to these two winds. Seven section lines 30 m apart and normal to the dune crest were surveyed regularly over the period of a year to monitor the reversal process. Three detailed topographic surveys were also done during this period. Airflow behaviour was monitored during the year. Wind speed profiles on the windward slope of the dune were measured using 4 to 5 vertical arrays of anemometers positioned from the base of the dune to the crest on a 1 selected section line. Usually 4 to 5 anemometers were deployed in each vertical array, from a height of 6 to 10 cm above the surface, up to a height of 150 cm above the surface. Initially 8 microanemometers were available; ultimately 28 anemometers were run simultaneously. An independent weather station at an elevation of 6 m recorded the unaccelerated flow. Local gradient measurements and erosion and deposition rates were recorded along selected section lines. Strong summer easterly winds (14 m/sec at 1.4 m above the dune crest) were measured on a dune slope in the process of being transformed from a slipface to a stoss slope. The following winter, light north-westerly winds (typically B m/sec at 1.6 m above the dune crest) were measured on the new windward slope already reversed by the prevailing winter wind. Airflow data confirm the compression of airflow against the windward slope resulting in a non-logarithmic wind speed profile. Compression results in an increased shear velocity within 30 cm of the dune surface, and the dune slope is eroded. Higher up in the wind speed profile, shear velocity decreases to 0.1 m/sec. It is not known at what height the wind speed profile recovers from the intrusion of the dune into the boundary layer. High values of shear velocity (1.6 m/sec) above the rounded crestal area of the dune record the recovery of the wind speed profile from flow divergence, which is a response to the rapid reduction of dune gradient and is accompanied by deposition of sand in this region. 2 The erosion pin data act as a simple and sensitive test for changes in gradient, reflecting the dune's response to changes in the airflow regime. The shape of the dune plays a major role in determining the extent of the compression and the distribution of shear velocity up the slope. Increased shear velocity is experienced on that part of the slope which is nonaerodynamic with respect to the prevailing wind. Under unidirectional conditions, feedback between flow and form results ultimately in a slope with a curvature such that shear velocity increases systematically upslope. The survey data and erosion pin data record the reversal process as the dune achieves a new steady state during each wind season. The existence of a non-logarithmic wind speed profile makes it difficult to know what relevant measure of shear velocity is to be used in sand transport equations. Future work should include wind speed measurements within 10 cm of the surface. An ideal study modelling aeolian bedform development would utilise wind tunnel measurements, combined with field measurements such as obtained in this study, for comparison with numerical modelling. The study needs to be extended to 3-dimensional airflow measurements. , Thesis (MSc) -- Faculty of Science, School of Environmental Sciences, 2021
- Full Text:
- Date Issued: 2021-04
- Authors: Burkinshaw, Jennifer Ruth
- Date: 2021-04
- Subjects: Port Elizabeth (South Africa) , Eastern Cape (South Africa) , South Africa
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10948/52734 , vital:43883
- Description: Our understanding of the evolution of dune morphology has been hampered by a lack of empirical observations of airflow behaviour over dune forms. Sand dunes intrude into the atmospheric boundary layer and convergence of streamlines results in an acceleration of airflow up the windward slopes of dunes. This study examines the airflow structure and corresponding bedform development on the windward slope of a 7 m high transverse dune on the edge of the Alexandria coastal dunefield, Algoa Bay, South Africa. The Alexandria dunefield is subjected to a trimodal wind regime, consisting of the dominant south-westerly which blows all year round, summer easterlies and winter northwesterlies. The morphology of the study dune, Dune13, is controlled by the easterlies and north-westerlies, and reverses seasonally with respect to these two winds. Seven section lines 30 m apart and normal to the dune crest were surveyed regularly over the period of a year to monitor the reversal process. Three detailed topographic surveys were also done during this period. Airflow behaviour was monitored during the year. Wind speed profiles on the windward slope of the dune were measured using 4 to 5 vertical arrays of anemometers positioned from the base of the dune to the crest on a 1 selected section line. Usually 4 to 5 anemometers were deployed in each vertical array, from a height of 6 to 10 cm above the surface, up to a height of 150 cm above the surface. Initially 8 microanemometers were available; ultimately 28 anemometers were run simultaneously. An independent weather station at an elevation of 6 m recorded the unaccelerated flow. Local gradient measurements and erosion and deposition rates were recorded along selected section lines. Strong summer easterly winds (14 m/sec at 1.4 m above the dune crest) were measured on a dune slope in the process of being transformed from a slipface to a stoss slope. The following winter, light north-westerly winds (typically B m/sec at 1.6 m above the dune crest) were measured on the new windward slope already reversed by the prevailing winter wind. Airflow data confirm the compression of airflow against the windward slope resulting in a non-logarithmic wind speed profile. Compression results in an increased shear velocity within 30 cm of the dune surface, and the dune slope is eroded. Higher up in the wind speed profile, shear velocity decreases to 0.1 m/sec. It is not known at what height the wind speed profile recovers from the intrusion of the dune into the boundary layer. High values of shear velocity (1.6 m/sec) above the rounded crestal area of the dune record the recovery of the wind speed profile from flow divergence, which is a response to the rapid reduction of dune gradient and is accompanied by deposition of sand in this region. 2 The erosion pin data act as a simple and sensitive test for changes in gradient, reflecting the dune's response to changes in the airflow regime. The shape of the dune plays a major role in determining the extent of the compression and the distribution of shear velocity up the slope. Increased shear velocity is experienced on that part of the slope which is nonaerodynamic with respect to the prevailing wind. Under unidirectional conditions, feedback between flow and form results ultimately in a slope with a curvature such that shear velocity increases systematically upslope. The survey data and erosion pin data record the reversal process as the dune achieves a new steady state during each wind season. The existence of a non-logarithmic wind speed profile makes it difficult to know what relevant measure of shear velocity is to be used in sand transport equations. Future work should include wind speed measurements within 10 cm of the surface. An ideal study modelling aeolian bedform development would utilise wind tunnel measurements, combined with field measurements such as obtained in this study, for comparison with numerical modelling. The study needs to be extended to 3-dimensional airflow measurements. , Thesis (MSc) -- Faculty of Science, School of Environmental Sciences, 2021
- Full Text:
- Date Issued: 2021-04