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
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
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
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
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
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
The effect of silicon on palladium migration in pyrolytic carbon and graphite
- Authors: Downey, Justin Michael
- 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/10948/53665 , vital:45684
- Description: The pebble-bed reactor (PBR) is a graphite-moderated, gas-cooled high temperature nuclear reactor design and it is one of six nuclear reactor concepts included in the Generation IV initiative. Pebble-bed reactors use spherical fuel elements (called pebbles) which consist of pyrolytic graphite (which acts as the moderator) and contain thousands of micro-fuel particles called tristructural isotropic (TRISO) particles. These TRISO fuel particles consist of a fissile material (such as U235 in oxide or carbide form) surrounded by a carbon buffer layer, a pyrolytic carbon (PyC) layer, a silicon carbide (SiC) ceramic layer for structural integrity and metallic fission product containment, and an outer PyC layer. The PBR is claimed to be a passively safe design. The commercial development of the first pebble bed reactor was that of the German AVR reactor (German: Arbeitsgemeinschaft Versuchsreaktor) developed during the 1960s. The AVR design was later updated and marketed by a company called HTR. In 1999 the South African electricity company ESKOM obtained the right to access the HTR engineering database that included details of the Siemens/Interatom HTR-Module design. ESKOM worked with HTR on a new design and dubbed it the pebble bed modular reactor (PBMR). The PBMR Co. Ltd. was formed in 1999 and mandated to license and build PBMR reactors. One of the safety considerations which emerged from research is that of metal fission product release from the TRISO fuel particles. Ag110m is a radioactive metallic fission product found to have been released from intact TRISO particles. The release of this Ag isotope is of particular concern because it is highly gamma active and has a half-life of approximately 250 days, resulting in unsafe environments for maintenance workers of PBRs. During the past four decades, many different mechanisms for Ag transport in SiC and release from TRISO particles have been proposed. A promising more recent mechanism suggests that the metallic fission product palladium (Pd) plays a significant role in the transport and release of Ag from intact TRISO particles. In this mechanism Ag transport in irradiated TRISO particle fuel takes place in the presence of the fission product Pd. The Pd reacts with the SiC layer and penetrates the SiC layer along grain boundaries to form a silicide layer which provides a rapid diffusion path for Ag in the SiC. The presence of thin silicide layers in irradiated TRISO particles was subsequently confirmed. , Thesis (PhD) -- Faculty of Science, School of Computer Science, Mathematics, Physics and Statistics, 2021
- Full Text: false
- Date Issued: 2021-12
- Authors: Downey, Justin Michael
- 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/10948/53665 , vital:45684
- Description: The pebble-bed reactor (PBR) is a graphite-moderated, gas-cooled high temperature nuclear reactor design and it is one of six nuclear reactor concepts included in the Generation IV initiative. Pebble-bed reactors use spherical fuel elements (called pebbles) which consist of pyrolytic graphite (which acts as the moderator) and contain thousands of micro-fuel particles called tristructural isotropic (TRISO) particles. These TRISO fuel particles consist of a fissile material (such as U235 in oxide or carbide form) surrounded by a carbon buffer layer, a pyrolytic carbon (PyC) layer, a silicon carbide (SiC) ceramic layer for structural integrity and metallic fission product containment, and an outer PyC layer. The PBR is claimed to be a passively safe design. The commercial development of the first pebble bed reactor was that of the German AVR reactor (German: Arbeitsgemeinschaft Versuchsreaktor) developed during the 1960s. The AVR design was later updated and marketed by a company called HTR. In 1999 the South African electricity company ESKOM obtained the right to access the HTR engineering database that included details of the Siemens/Interatom HTR-Module design. ESKOM worked with HTR on a new design and dubbed it the pebble bed modular reactor (PBMR). The PBMR Co. Ltd. was formed in 1999 and mandated to license and build PBMR reactors. One of the safety considerations which emerged from research is that of metal fission product release from the TRISO fuel particles. Ag110m is a radioactive metallic fission product found to have been released from intact TRISO particles. The release of this Ag isotope is of particular concern because it is highly gamma active and has a half-life of approximately 250 days, resulting in unsafe environments for maintenance workers of PBRs. During the past four decades, many different mechanisms for Ag transport in SiC and release from TRISO particles have been proposed. A promising more recent mechanism suggests that the metallic fission product palladium (Pd) plays a significant role in the transport and release of Ag from intact TRISO particles. In this mechanism Ag transport in irradiated TRISO particle fuel takes place in the presence of the fission product Pd. The Pd reacts with the SiC layer and penetrates the SiC layer along grain boundaries to form a silicide layer which provides a rapid diffusion path for Ag in the SiC. The presence of thin silicide layers in irradiated TRISO particles was subsequently confirmed. , Thesis (PhD) -- Faculty of Science, School of Computer Science, Mathematics, Physics and Statistics, 2021
- Full Text: false
- Date Issued: 2021-12
Ureaplasma species in the placenta and histopathology associated with preterm birth
- Authors: Sprong, Kaitlin Elizabeth
- 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/10948/54128 , vital:46310
- Description: The Eastern Cape province is known for its high perinatal morbidity and mortality rate. Studies from other countries indicate that Ureaplasma spp. have been associated with clinical chorioamnionitis, spontaneous preterm labor and preterm premature rupture of the fetal membranes. The prevalence of Ureaplasma urealyticum, Ureaplasma parvumand Mycoplasma hominisin the placenta and its role in preterm birth is unknown in South Africa. Objectives The objectives of this study were to: (i) analyze placental histology, maternal and neonatal outcomes and clinical presentation of preterm birth, (ii) detect Ureaplasma spp. and M. hominisin the placenta from cases of preterm birth, (iii) determine antibiotic susceptibility profiles of Ureaplasma spp. isolates and investigate mechanisms of antibiotic resistance, (iv) characterize the microbial diversity in the placenta using 16S rRNA next generation sequencing and(v) review pathologies to ascertain whether there is any association between Ureaplasma spp. in the placenta and adverse maternal, obstetric and neonatal outcomes. iiiABSTRACTBackground The Eastern Cape province is known for its high perinatal morbidity and mortality rate. Studies from other countries indicate that Ureaplasmaspp. have been associated with clinical chorioamnionitis, spontaneous preterm labor and preterm premature rupture of the fetal membranes. The prevalenceof Ureaplasmaurealyticum,UreaplasmaparvumandMycoplasmahominisin the placenta andits role in preterm birth is unknown in South Africa. Objectives The objectives of this study were to: (i) analyze placental histology, maternal and neonatal outcomes and clinical presentation of preterm birth, (ii) detect Ureaplasmaspp. and M. hominisin the placenta from cases of preterm birth, (iii) determine antibiotic susceptibility profiles of Ureaplasmaspp. isolates and investigate mechanisms of antibiotic resistance, (iv) characterize the microbial diversity in the placenta using 16S rRNA next generation sequencing and(v) review pathologies to ascertain whether there is any association between Ureaplasmaspp. inthe placenta and adverse maternal, obstetric and neonatal outcomes. MethodsPlacentas were collected from patients presenting with preterm birth (n=100; 28-34 weeks gestational age) and term birth (n=20; >38 weeks) regardless of the APGAR score. Placentas were submitted for histopathology and used for detection of Ureaplasmaspp. by culture (U9 broth, MycoDuo kits;BioRad) and PCR (DNA was extracted from culture and homogenized placental tissue). Antibiotic susceptibility profiles of Ureaplasmaspp isolates were determined by the SIR Antibiogram kit (BioRad) and microbroth dilution method. Molecular mechanisms of resistance were ascertained by PCR amplification of target genes. Placentas were sent to National Health Laboratory Servicesfor routine histopathology. Next generation sequencing was performed on 16S rRNA amplicons from placental DNA for analysis of microbial diversity. , Thesis (PhD) -- Faculty of Science, Journalsim and Media Studies, 2021
- Full Text:
- Date Issued: 2021-12
- Authors: Sprong, Kaitlin Elizabeth
- 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/10948/54128 , vital:46310
- Description: The Eastern Cape province is known for its high perinatal morbidity and mortality rate. Studies from other countries indicate that Ureaplasma spp. have been associated with clinical chorioamnionitis, spontaneous preterm labor and preterm premature rupture of the fetal membranes. The prevalence of Ureaplasma urealyticum, Ureaplasma parvumand Mycoplasma hominisin the placenta and its role in preterm birth is unknown in South Africa. Objectives The objectives of this study were to: (i) analyze placental histology, maternal and neonatal outcomes and clinical presentation of preterm birth, (ii) detect Ureaplasma spp. and M. hominisin the placenta from cases of preterm birth, (iii) determine antibiotic susceptibility profiles of Ureaplasma spp. isolates and investigate mechanisms of antibiotic resistance, (iv) characterize the microbial diversity in the placenta using 16S rRNA next generation sequencing and(v) review pathologies to ascertain whether there is any association between Ureaplasma spp. in the placenta and adverse maternal, obstetric and neonatal outcomes. iiiABSTRACTBackground The Eastern Cape province is known for its high perinatal morbidity and mortality rate. Studies from other countries indicate that Ureaplasmaspp. have been associated with clinical chorioamnionitis, spontaneous preterm labor and preterm premature rupture of the fetal membranes. The prevalenceof Ureaplasmaurealyticum,UreaplasmaparvumandMycoplasmahominisin the placenta andits role in preterm birth is unknown in South Africa. Objectives The objectives of this study were to: (i) analyze placental histology, maternal and neonatal outcomes and clinical presentation of preterm birth, (ii) detect Ureaplasmaspp. and M. hominisin the placenta from cases of preterm birth, (iii) determine antibiotic susceptibility profiles of Ureaplasmaspp. isolates and investigate mechanisms of antibiotic resistance, (iv) characterize the microbial diversity in the placenta using 16S rRNA next generation sequencing and(v) review pathologies to ascertain whether there is any association between Ureaplasmaspp. inthe placenta and adverse maternal, obstetric and neonatal outcomes. MethodsPlacentas were collected from patients presenting with preterm birth (n=100; 28-34 weeks gestational age) and term birth (n=20; >38 weeks) regardless of the APGAR score. Placentas were submitted for histopathology and used for detection of Ureaplasmaspp. by culture (U9 broth, MycoDuo kits;BioRad) and PCR (DNA was extracted from culture and homogenized placental tissue). Antibiotic susceptibility profiles of Ureaplasmaspp isolates were determined by the SIR Antibiogram kit (BioRad) and microbroth dilution method. Molecular mechanisms of resistance were ascertained by PCR amplification of target genes. Placentas were sent to National Health Laboratory Servicesfor routine histopathology. Next generation sequencing was performed on 16S rRNA amplicons from placental DNA for analysis of microbial diversity. , Thesis (PhD) -- Faculty of Science, Journalsim and Media Studies, 2021
- Full Text:
- Date Issued: 2021-12
A data-driven decision-making model for the third-party logistics industry in Africa
- Authors: Moyo, Faith
- 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/10948/53875 , vital:46022
- Description: Third-party logistics (3PL) providers have continued to be key players in the supply chain network and have witnessed a growth in the usage of information technology. This growth has enhanced the volume of structured and unstructured data that is collected at a high velocity, and is of rich variety, sometimes described as “Big Data”. Leaders in the 3PL industry are constantly seeking to effectively and efficiently mature their abilities to exploit this data to gain business value through data-driven decision-making (DDDM). DDDM helps the leaders to reduce the reliance they place on observations and intuition to make crucial business decisions in a volatile business environment. The aim of this research was to develop a prescriptive model for DDDM in 3PLs. The model consists of iterative elements that prescribe guidelines to decision-makers in the 3PL industry on how to adopt DDDM. A literature review of existing theoretical frameworks and models for DDDM was conducted to determine the extent to which they contribute towards DDDM for 3PLs. The Design-Science Research Methodology (DSRM) was followed to address the aim of the research and applied to pragmatically and iteratively develop and evaluate the artefact (the model for DDDM) in the real-world context of a 3PL. The literature findings revealed that the challenges with DDDM in organisations include three main categories of challenges related to data quality, data management, vision and capabilities. Once the challenges with DDDM were established, a prescriptive model was designed and developed for DDDM in 3PLs. Qualitative data was collected from semi-structured interviews to gain an understanding of the problems and possible solutions in the real-world context of 3PLs. An As-Is Analysis in the real-world case 3PL company confirmed the challenges identified in literature, and that data is still used in the 3PL company for descriptive and diagnostic analytics to aid with the decision-making processes. This highlights that there is still room for maturity into using data for predictive and prescriptive analytics that will, in turn, improve the decision-making process. An improved second version of the model was demonstrated to the participants (the targeted users), who had the opportunity to evaluate the model. The findings revealed that the model provided clear guidelines on how to make data-driven decisions and that the feedback loop and the data culture aspects highlighted in the design were some of the important features of the model. Some improvements were suggested by participants. A field study of three data analytics tools was conducted to identify the advantages and disadvantages of each as well as to highlight the status of DDDM at the real-world case 3PL. The limitations of the second version of the model, together with the recommendations from the participants were used to inform the improved and revised third version of the model. , Thesis (MSc) -- Faculty of Science, School of Computer Science, Mathematics, Physics and Statistics, 2021
- Full Text:
- Date Issued: 2021-12
- Authors: Moyo, Faith
- 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/10948/53875 , vital:46022
- Description: Third-party logistics (3PL) providers have continued to be key players in the supply chain network and have witnessed a growth in the usage of information technology. This growth has enhanced the volume of structured and unstructured data that is collected at a high velocity, and is of rich variety, sometimes described as “Big Data”. Leaders in the 3PL industry are constantly seeking to effectively and efficiently mature their abilities to exploit this data to gain business value through data-driven decision-making (DDDM). DDDM helps the leaders to reduce the reliance they place on observations and intuition to make crucial business decisions in a volatile business environment. The aim of this research was to develop a prescriptive model for DDDM in 3PLs. The model consists of iterative elements that prescribe guidelines to decision-makers in the 3PL industry on how to adopt DDDM. A literature review of existing theoretical frameworks and models for DDDM was conducted to determine the extent to which they contribute towards DDDM for 3PLs. The Design-Science Research Methodology (DSRM) was followed to address the aim of the research and applied to pragmatically and iteratively develop and evaluate the artefact (the model for DDDM) in the real-world context of a 3PL. The literature findings revealed that the challenges with DDDM in organisations include three main categories of challenges related to data quality, data management, vision and capabilities. Once the challenges with DDDM were established, a prescriptive model was designed and developed for DDDM in 3PLs. Qualitative data was collected from semi-structured interviews to gain an understanding of the problems and possible solutions in the real-world context of 3PLs. An As-Is Analysis in the real-world case 3PL company confirmed the challenges identified in literature, and that data is still used in the 3PL company for descriptive and diagnostic analytics to aid with the decision-making processes. This highlights that there is still room for maturity into using data for predictive and prescriptive analytics that will, in turn, improve the decision-making process. An improved second version of the model was demonstrated to the participants (the targeted users), who had the opportunity to evaluate the model. The findings revealed that the model provided clear guidelines on how to make data-driven decisions and that the feedback loop and the data culture aspects highlighted in the design were some of the important features of the model. Some improvements were suggested by participants. A field study of three data analytics tools was conducted to identify the advantages and disadvantages of each as well as to highlight the status of DDDM at the real-world case 3PL. The limitations of the second version of the model, together with the recommendations from the participants were used to inform the improved and revised third version of the model. , Thesis (MSc) -- Faculty of Science, School of Computer Science, Mathematics, Physics and Statistics, 2021
- Full Text:
- Date Issued: 2021-12
The use of ambient seismic noise to investigate internal changes in a tailings storage facility and to image the subsurface geology in the Cradock area of the Eastern Cape
- Authors: Kunjwa, Thulisile
- 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/10948/53642 , vital:45690
- Description: Passive seismic interferometry is a process by which ambient noise data recorded at different seismic stations can be cross-correlated to estimate Green's functions. In the past, both surface waves and body waves have successfully been extracted by cross-correlation of ambient noise data on both regional and global scales. Recent advancements in ambient seismic noise techniques have the potential to provide new methods for subsurface imaging and monitoring. The ambient noise data processing procedure divides into four principal phases: (1) single station data preparation, (2) cross-correlation and temporal stacking, (3) measurement of dispersion curves and (4) inversion of dispersion curves to obtain 1-D shear wave profiles and computation of 2-D shear wave velocity cross-section. The purpose of this study is to investigate whether ambient seismic noise can be used to image and detect internal changes within a mine tailings dam wall and to image the subsurface geology of part of the Eastern Cape Karoo near Cradock. In the first experiment, the investigation consisted of continuous ambient noise data recordings over a period of 3 days with 20 three-component short period geophones. The geophones were deployed over a survey wall of roughly 100 m in length at the Harmony Gold mine tailings dam in Welkom. In the second experiment, the investigation consisted of data recordings over a period of 35 days. The geophones were deployed in Cradock. The first phase of the data processing procedure included de-trending, de-meaning and band-pass filtering the data. This was done to ensure that any long period trends associated with instrument glitches are removed from the data. A spectrogram was then computed to view the spectrum of frequencies in the signal and to check if the filter that was designed was able to cut off the unwanted frequencies. The horizontal and vertical components of the ambient noise data were cross-correlated and picked between sensor pairs to create surface wave dispersion curves. Subsequently, the dispersion curves were inverted to estimate the shear wave velocity of the dam wall and subsurface as a function of depth. The computed cross sections of shear wave velocity indicated a low-velocity zone between 2 and 10 m below the surface on the dam wall, this suggested that the phreatic surface is much closer to surface in this area. In the second experiment, the interpolated shear wave velocity profiles indicated that there is a layer of low velocity zone between depths 250 to 300 m below the surface. The cross-correlations were also used to compute group velocity maps from periods 1.5 seconds to 30 seconds. The group velocity maps showed various high and low velocity anomalies. The high velocity zones observed on the eastern section of the map were interpreted as evidence of dolerite intrusions. The low velocity zones observed in the western and southern sections of the map interpreted as Karoo sediments that belong to the Adelaide Subgroup which is dominated by mudstones. , Thesis (MSc) -- Faculty of Science, Department of Geosciences (Geology and Geography), 2021
- Full Text:
- Date Issued: 2021-12
- Authors: Kunjwa, Thulisile
- 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/10948/53642 , vital:45690
- Description: Passive seismic interferometry is a process by which ambient noise data recorded at different seismic stations can be cross-correlated to estimate Green's functions. In the past, both surface waves and body waves have successfully been extracted by cross-correlation of ambient noise data on both regional and global scales. Recent advancements in ambient seismic noise techniques have the potential to provide new methods for subsurface imaging and monitoring. The ambient noise data processing procedure divides into four principal phases: (1) single station data preparation, (2) cross-correlation and temporal stacking, (3) measurement of dispersion curves and (4) inversion of dispersion curves to obtain 1-D shear wave profiles and computation of 2-D shear wave velocity cross-section. The purpose of this study is to investigate whether ambient seismic noise can be used to image and detect internal changes within a mine tailings dam wall and to image the subsurface geology of part of the Eastern Cape Karoo near Cradock. In the first experiment, the investigation consisted of continuous ambient noise data recordings over a period of 3 days with 20 three-component short period geophones. The geophones were deployed over a survey wall of roughly 100 m in length at the Harmony Gold mine tailings dam in Welkom. In the second experiment, the investigation consisted of data recordings over a period of 35 days. The geophones were deployed in Cradock. The first phase of the data processing procedure included de-trending, de-meaning and band-pass filtering the data. This was done to ensure that any long period trends associated with instrument glitches are removed from the data. A spectrogram was then computed to view the spectrum of frequencies in the signal and to check if the filter that was designed was able to cut off the unwanted frequencies. The horizontal and vertical components of the ambient noise data were cross-correlated and picked between sensor pairs to create surface wave dispersion curves. Subsequently, the dispersion curves were inverted to estimate the shear wave velocity of the dam wall and subsurface as a function of depth. The computed cross sections of shear wave velocity indicated a low-velocity zone between 2 and 10 m below the surface on the dam wall, this suggested that the phreatic surface is much closer to surface in this area. In the second experiment, the interpolated shear wave velocity profiles indicated that there is a layer of low velocity zone between depths 250 to 300 m below the surface. The cross-correlations were also used to compute group velocity maps from periods 1.5 seconds to 30 seconds. The group velocity maps showed various high and low velocity anomalies. The high velocity zones observed on the eastern section of the map were interpreted as evidence of dolerite intrusions. The low velocity zones observed in the western and southern sections of the map interpreted as Karoo sediments that belong to the Adelaide Subgroup which is dominated by mudstones. , Thesis (MSc) -- Faculty of Science, Department of Geosciences (Geology and Geography), 2021
- Full Text:
- Date Issued: 2021-12
In-vitroevaluation of bridelia ferruginea extract gold nanoparticles for the treatment of colon cancer
- Zosela, Itumeleng, Davids, Hajierah
- Authors: Zosela, Itumeleng , Davids, Hajierah
- 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/10948/54124 , vital:46311
- Description: Colorectal cancer (CRC) has become a health burden, being the third common cancer worldwide. Treatment of colorectal cancer is very important to manage the high prevalence rate of this disease. The available treatments for CRC have their drawbacks and side effects. Available treatments of colon cancer include surgery, chemotherapy, and radiation. Due to the side effects associated with these treatments, alternative treatments that pose less side effects are being developed worldwide. Nanotechnologies have gained global consideration due to their potential to improve the current standards and techniques for the diagnosis and treatment. The use of plants for synthesis of gold nanoparticles has opened a new venture of synthesizing environmentally friendly and cost-effective nanoparticles which possess great properties for CRC treatment. The aim of this study was to investigate the use of green synthesized AuNPs from Bridelia ferruginea for potential cancer treatment. In this work study gold nanoparticles were synthesized utilizing Bridelia ferruginea stem bark extract. The nanoparticles were characterized using UV–Vis spectroscopy, Dynamic Light Scattering (DLS), Fourier Transform Infrared Spectroscopy (FTIR) and High-Resolution Transmission Electron Microscopy (HRTEM). The in vitroanti cancer activity of the AuNPs was investigated using Presto Blue assay, cellular morphology, caspase 3/7 assay on the human colon cancer cell line at different times to assess the optimum time for cell death. The cellular uptake and localization of AuNPs was investigated using HRTEM to assess uptake and location of the AuNPs within the cell. Results obtained from this study showed that the AuNP synthesis from Bridellia ferrugenia was successful. The Presto Blue cell viability results showed that the AuNPs reduced cell viability (%) significantly (p<0.05) after 24 h. The optimum treatment time of HT-29 cells with AuNPs was determined to be 24 h. The apoptotic effects of the AuNPs were assessed using Cell Event reagent, and the results from this assay indicated that caspase 3/7 was activated with treatment with AuNPs which induced cell death via apoptosis. The HRTEM results indicated that there was no uptake of AuNP targeting in HT-29 therefore localization could not be determined. It can be concluded that the AuNPs synthesized from Bridellia ferrugenia have anti-cancer properties and are able to induce cell death through apoptosis. Furthermore, this study revealed that optimization of the AuNPs for cellular uptake is needed to further understand the interaction between the nanoparticles and the cells. This will provide more insight on how cellular death is induced by the nanoparticles. , Thesis (MSc) -- Faculty of Science, Department of Biochemistry and Microbiology (including Physiology), 2021
- Full Text:
- Date Issued: 2021-12
- Authors: Zosela, Itumeleng , Davids, Hajierah
- 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/10948/54124 , vital:46311
- Description: Colorectal cancer (CRC) has become a health burden, being the third common cancer worldwide. Treatment of colorectal cancer is very important to manage the high prevalence rate of this disease. The available treatments for CRC have their drawbacks and side effects. Available treatments of colon cancer include surgery, chemotherapy, and radiation. Due to the side effects associated with these treatments, alternative treatments that pose less side effects are being developed worldwide. Nanotechnologies have gained global consideration due to their potential to improve the current standards and techniques for the diagnosis and treatment. The use of plants for synthesis of gold nanoparticles has opened a new venture of synthesizing environmentally friendly and cost-effective nanoparticles which possess great properties for CRC treatment. The aim of this study was to investigate the use of green synthesized AuNPs from Bridelia ferruginea for potential cancer treatment. In this work study gold nanoparticles were synthesized utilizing Bridelia ferruginea stem bark extract. The nanoparticles were characterized using UV–Vis spectroscopy, Dynamic Light Scattering (DLS), Fourier Transform Infrared Spectroscopy (FTIR) and High-Resolution Transmission Electron Microscopy (HRTEM). The in vitroanti cancer activity of the AuNPs was investigated using Presto Blue assay, cellular morphology, caspase 3/7 assay on the human colon cancer cell line at different times to assess the optimum time for cell death. The cellular uptake and localization of AuNPs was investigated using HRTEM to assess uptake and location of the AuNPs within the cell. Results obtained from this study showed that the AuNP synthesis from Bridellia ferrugenia was successful. The Presto Blue cell viability results showed that the AuNPs reduced cell viability (%) significantly (p<0.05) after 24 h. The optimum treatment time of HT-29 cells with AuNPs was determined to be 24 h. The apoptotic effects of the AuNPs were assessed using Cell Event reagent, and the results from this assay indicated that caspase 3/7 was activated with treatment with AuNPs which induced cell death via apoptosis. The HRTEM results indicated that there was no uptake of AuNP targeting in HT-29 therefore localization could not be determined. It can be concluded that the AuNPs synthesized from Bridellia ferrugenia have anti-cancer properties and are able to induce cell death through apoptosis. Furthermore, this study revealed that optimization of the AuNPs for cellular uptake is needed to further understand the interaction between the nanoparticles and the cells. This will provide more insight on how cellular death is induced by the nanoparticles. , Thesis (MSc) -- Faculty of Science, Department of Biochemistry and Microbiology (including Physiology), 2021
- Full Text:
- Date Issued: 2021-12
Real-time feedback model for supporting individualised learning of programming students
- Authors: Keen, Charne
- 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/10948/53624 , vital:45691
- Description: Feedback is crucial to the enhancement of the learning and teaching environment, especially in those environments that suffer from a number of extrinsic challenges. The growing demands for educators to provide academic interventions throughout the lecture session and the need for continuous improvement of the quality of university education make it necessary to find and apply more effective and efficient educational technologies and practices based on the correlation of teaching with a student’s conceptual understanding and individual learning preference. Following a combination of Design Science Research (DSR) and Case Study Methodology, this research addresses this problem by designing a technology based real-time feedback (TBRTF) model that can easily be implemented in a South African University. The model designed followed a layered architecture pattern. The architecture describes the data, technology and user support layers of the model. The data support layer incorporates the collection of student academic data and learning preferences. The technology incorporates a machine learning component. The machine learning component covers two technological aspects: the prediction component and the clustering component. This TBRTF model provides the guidelines needed to develop a system that supports individualised real-time feedback in the learning and teaching environment of programming students. The aim of the model is that as the students partake in learning activities where the student data is updated, the monitoring component will fire, updating the probability of failure prediction and in turn the student clusters are regenerated. This will notify the educator of a change and provide decision making support. The student will be allocated individualised feedback in the form of learning materials based on the cluster that the student is allocated to. Through a demonstration and evaluation, this study showed that by following the proposed architecture of the TBRTF model, a model that supports individualised realtime feedback in the learning and teaching environment of programming students can be developed. The validation used an artificial neural network as the prediction component and a k-means clustering algorithm as the clustering component. , Thesis (MSc) -- Faculty of Science, School of Computer Science, Mathematics, Physics and Statistics, 2021
- Full Text: false
- Date Issued: 2021-12
- Authors: Keen, Charne
- 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/10948/53624 , vital:45691
- Description: Feedback is crucial to the enhancement of the learning and teaching environment, especially in those environments that suffer from a number of extrinsic challenges. The growing demands for educators to provide academic interventions throughout the lecture session and the need for continuous improvement of the quality of university education make it necessary to find and apply more effective and efficient educational technologies and practices based on the correlation of teaching with a student’s conceptual understanding and individual learning preference. Following a combination of Design Science Research (DSR) and Case Study Methodology, this research addresses this problem by designing a technology based real-time feedback (TBRTF) model that can easily be implemented in a South African University. The model designed followed a layered architecture pattern. The architecture describes the data, technology and user support layers of the model. The data support layer incorporates the collection of student academic data and learning preferences. The technology incorporates a machine learning component. The machine learning component covers two technological aspects: the prediction component and the clustering component. This TBRTF model provides the guidelines needed to develop a system that supports individualised real-time feedback in the learning and teaching environment of programming students. The aim of the model is that as the students partake in learning activities where the student data is updated, the monitoring component will fire, updating the probability of failure prediction and in turn the student clusters are regenerated. This will notify the educator of a change and provide decision making support. The student will be allocated individualised feedback in the form of learning materials based on the cluster that the student is allocated to. Through a demonstration and evaluation, this study showed that by following the proposed architecture of the TBRTF model, a model that supports individualised realtime feedback in the learning and teaching environment of programming students can be developed. The validation used an artificial neural network as the prediction component and a k-means clustering algorithm as the clustering component. , Thesis (MSc) -- Faculty of Science, School of Computer Science, Mathematics, Physics and Statistics, 2021
- Full Text: false
- Date Issued: 2021-12
A critical exploration of the attitudes towards and knowledge of natural resource management amongst first-year Natural Resource Management students
- Authors: Jooste, Eileen
- Date: 2021-12
- Subjects: Port Elizabeth (South Africa) , Eastern Cape (South Africa) , South Africa
- Language: English
- Type: Master's , text
- Identifier: http://hdl.handle.net/10948/53666 , vital:45688
- Description: Available literature suggests that there is a need to gain more understanding of what students’ environmental attitudes and knowledge are and how they are developed by education systems. Education, in general, plays an important role in students’ attitudes and their knowledge of the world around them. It can shape students’ awareness of their natural environment and contribute to their understanding of environmental issues. Education can also strengthen students’ critical thinking, build awareness, stimulate problem solving, and promote sustainable practices. It has the potential to empower students to address global challenges from their own diverse perspectives and prepare them to uphold the economy. Education can improve and maintain societal wellbeing and can help students to maintain the natural environment, along with achieving sustainable development. Environmental education, specifically, can play a big role in how students deal with the natural environment. The primary aim of this qualitative research study was to examine first-year students’ environmental attitudes and knowledge in the School of Natural Resource Management at the Nelson Mandela University George Campus, South Africa. First-year students’ environmental attitudes and knowledge were examined as they entered the university, and then again at the end of the first semester once they had completed a module in ecology. More specifically, at the outset of the research the objectives were (1) to establish an understanding of the baseline environmental attitudes and knowledge of first-year students who were undertaking three ecological modules being offered by the School of Natural Resource Management; (2) to assess the changes in the first-year students’ environmental attitudes and knowledge, using a post-intervention strategy; (3) to understand what type of teaching approaches were used by the lecturers teaching the ecological modules; and (4) to evaluate how the teaching approaches of the lecturers influenced the baseline environmental attitudes and knowledge of the student group. This research took place in the midst of the Corona Virus pandemic, which had significantly influenced the teaching and learning environment. Multiple education systems, including those of the Nelson Mandela University George Campus, had to rapidly transition to online teaching and learning. So, although unplanned for, this research could not ignore the rapid transition to online teaching and learning and the role it played in shaping the first-year School of Natural Resource Management students’ environmental attitudes and knowledge. It also impacted the teaching approaches of the environmental lecturers. An additional objective in response to the rapid transition to online teaching and learning was, therefore, added: (5) to understand the experiences of the first-year School of Natural Resource Management students and the three environmental lecturers who had to rapidly transition to online teaching and learning. Data was collected via questionnaires and semi-structured interviews with students and staff in the School of Natural Resource Management at Nelson Mandela University George Campus within three different natural resource management programs, namely Agriculture, Nature Conservation, and Forestry. Baseline questionnaires were conducted with 107 students for a baseline assessment as the students entered the university. An online post-intervention questionnaire was conducted with 33 of the initial group of students at the end of the semester for a post-intervention assessment. In-depth semi-structured interviews were conducted with three environmental lectures before they taught their three ecology modules in each of the programs. Additional online semi-structured interviews were also done with the same three environmental lectures after the rapid transition to online teaching and learning took place. The significant findings from this research were analyzed and discussed. This included the baseline environmental attitudes and knowledge of the student body upon arrival at the university and the changes in their environmental attitudes and knowledge after they were exposed to the ecology modules taught in each of the programs. The discussion also included the teaching approaches adopted by the environmental lecturers and the influence their teaching approaches had on the students’ environmental attitudes and knowledge. In addition, the results shed light on the experiences of students and lecturers during the rapid transition to online teaching and learning. The main conclusions reached were that the first-year School of Natural Resource Management students did not have a deep understanding of ecological concepts prior to arriving at university, but they did show a concern for the natural environment. Their lack of understanding was reduced as the students progressed with the ecology module. A greater understanding resulted in a change in students’ perspectives on the ecological module, their program, and the industry they were preparing to enter after being exposed to the ecology module. The environmental lecturers’ teaching approaches contributed to improving the students’ environmental attitudes and knowledge. When it came to the rapid transition to online teaching and learning, both the first-year School of Natural Resource Management students and environmental lecturers experienced benefits and challenges. , Thesis (MSc) -- Faculty of Science, School of Natural Resource Management, 2021
- Full Text:
- Date Issued: 2021-12
- Authors: Jooste, Eileen
- Date: 2021-12
- Subjects: Port Elizabeth (South Africa) , Eastern Cape (South Africa) , South Africa
- Language: English
- Type: Master's , text
- Identifier: http://hdl.handle.net/10948/53666 , vital:45688
- Description: Available literature suggests that there is a need to gain more understanding of what students’ environmental attitudes and knowledge are and how they are developed by education systems. Education, in general, plays an important role in students’ attitudes and their knowledge of the world around them. It can shape students’ awareness of their natural environment and contribute to their understanding of environmental issues. Education can also strengthen students’ critical thinking, build awareness, stimulate problem solving, and promote sustainable practices. It has the potential to empower students to address global challenges from their own diverse perspectives and prepare them to uphold the economy. Education can improve and maintain societal wellbeing and can help students to maintain the natural environment, along with achieving sustainable development. Environmental education, specifically, can play a big role in how students deal with the natural environment. The primary aim of this qualitative research study was to examine first-year students’ environmental attitudes and knowledge in the School of Natural Resource Management at the Nelson Mandela University George Campus, South Africa. First-year students’ environmental attitudes and knowledge were examined as they entered the university, and then again at the end of the first semester once they had completed a module in ecology. More specifically, at the outset of the research the objectives were (1) to establish an understanding of the baseline environmental attitudes and knowledge of first-year students who were undertaking three ecological modules being offered by the School of Natural Resource Management; (2) to assess the changes in the first-year students’ environmental attitudes and knowledge, using a post-intervention strategy; (3) to understand what type of teaching approaches were used by the lecturers teaching the ecological modules; and (4) to evaluate how the teaching approaches of the lecturers influenced the baseline environmental attitudes and knowledge of the student group. This research took place in the midst of the Corona Virus pandemic, which had significantly influenced the teaching and learning environment. Multiple education systems, including those of the Nelson Mandela University George Campus, had to rapidly transition to online teaching and learning. So, although unplanned for, this research could not ignore the rapid transition to online teaching and learning and the role it played in shaping the first-year School of Natural Resource Management students’ environmental attitudes and knowledge. It also impacted the teaching approaches of the environmental lecturers. An additional objective in response to the rapid transition to online teaching and learning was, therefore, added: (5) to understand the experiences of the first-year School of Natural Resource Management students and the three environmental lecturers who had to rapidly transition to online teaching and learning. Data was collected via questionnaires and semi-structured interviews with students and staff in the School of Natural Resource Management at Nelson Mandela University George Campus within three different natural resource management programs, namely Agriculture, Nature Conservation, and Forestry. Baseline questionnaires were conducted with 107 students for a baseline assessment as the students entered the university. An online post-intervention questionnaire was conducted with 33 of the initial group of students at the end of the semester for a post-intervention assessment. In-depth semi-structured interviews were conducted with three environmental lectures before they taught their three ecology modules in each of the programs. Additional online semi-structured interviews were also done with the same three environmental lectures after the rapid transition to online teaching and learning took place. The significant findings from this research were analyzed and discussed. This included the baseline environmental attitudes and knowledge of the student body upon arrival at the university and the changes in their environmental attitudes and knowledge after they were exposed to the ecology modules taught in each of the programs. The discussion also included the teaching approaches adopted by the environmental lecturers and the influence their teaching approaches had on the students’ environmental attitudes and knowledge. In addition, the results shed light on the experiences of students and lecturers during the rapid transition to online teaching and learning. The main conclusions reached were that the first-year School of Natural Resource Management students did not have a deep understanding of ecological concepts prior to arriving at university, but they did show a concern for the natural environment. Their lack of understanding was reduced as the students progressed with the ecology module. A greater understanding resulted in a change in students’ perspectives on the ecological module, their program, and the industry they were preparing to enter after being exposed to the ecology module. The environmental lecturers’ teaching approaches contributed to improving the students’ environmental attitudes and knowledge. When it came to the rapid transition to online teaching and learning, both the first-year School of Natural Resource Management students and environmental lecturers experienced benefits and challenges. , Thesis (MSc) -- Faculty of Science, School of Natural Resource Management, 2021
- Full Text:
- Date Issued: 2021-12
Ocean structures and dynamics of two open bays on the eastern Agulhas Bank
- Authors: Dlomo, Xolisa
- 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/10948/53607 , vital:45680
- Description: Upwelling, bay-scale currents, fronts and mixing in Algoa Bay and St Francis Bay occur over both short and long time periods. These physical ocean dynamics drive the temporal and spatial distribution of nutrients in the bays, there by influencing primary and secondary production. Thermal gradients and fronts are driven by the wind and open ocean influences, such as the Agulhas Current, daily and seasonal variations in solar radiation, long and short period waves, air-sea fluxes, coastal trapped waves and terrestrial freshwater inflow. These phenomena are poorly understood along this part of the coastline and were the focus of this study. I investigated the dominant temperature scales of variability in both bays, to determine which isotherm is best suited to describe temperature fluctuations and thermocline spatiotemporal variability in and between the two bays. I investigated upwelling spatiotemporal variability in the two bays and tested whether upwelling occurs at the opposite sides of the bays with a change in wind direction. Thereafter studied the occurrence and drivers of winter upwelling events. The wind-driven current spatiotemporal variability and correlations were investigated at the extremities of the two bays. The daily, intra-seasonal and yearly variation in temperature structures in Algoa Bay and St. Francis Bay were mainly driven by the local winds, coastal topography, and bathymetry. The most suitable isotherm to describe thermal fluctuations and variability in Algoa Bay shallower sites was 16.5 °C and its mean depth was 16.2 m. The best isotherm for the deeper sites in Algoa Bay was 15.7 °C with a depth of 33.1 m. The average temperature and depth of the best isotherm to describe thermal fluctuations in St. Francis Bay for the shallower sites was15.80 °C and 16.83 m, and for the deeper sites it was 15.10 °C and 32.08 m. Algoa Bay showed an average cooling trend of -0.000172 °C per year, whereas in St. Francis Bay a warming average trend of 0.0188 °C per year was observed over the study period often and six years, respectively. The wind, Coriolis Effect and Ekman Transport were the main external forces that influenced upwelling throughout the year. Since the available mesoscale indices for upwelling intensity lack the resolution needed to characterize and compare inner-shelf upwelling regimes at small spatial scales, I developed a new local, quantitative index of thermal variability. Index calculations were based on hourly records of in site depth-averaged temperatures, measured at 6 sites in St. Francis Bay and at 8 sites in Algoa Bay. Using the Multivariate Upwelling Zone Index of Cooling (MUZIC) I found that Woody Cape and Blue Horizon Bay had the highest upwelling intensity in Algoa Bay and St. Francis Bay, respectively. The other sites were ordinated and ranked according to their upwelling rates and intensity. Evidence of wind-driven winter upwelling was found to be a common occurrence in both bays. There was no obvious current seasonality observed, however, strong spectral signals in the period of a weather band (4 –7 days) were present. Current structures were generally positively correlated with wind variations in both bays. Thus, when westerly/easterly winds blew the overall surface current direction was eastward/westward. I observed a pronounced current spatiotemporal variability that was driven by local winds. The Bird Island surface currents in Algoa Bay were strongly correlated at 0–lag day with the winds, however, in Cape Recife the strongest correlations were usually observed at 1–lag day highlighting the spatiotemporal influence of wind regimes on current structures in Algoa Bay. Bird Island current speeds were higher and had an obvious bimodal directional variation (south westward /north eastward) compared to Cape Recife currents, which generally had a slower current speed with a strong west-north westward direction. In St. Francis Bay, the Schoenmakerskop surface currents showed weak positive correlation with winds at 0–lag day, however, stronger negative correlations were observed at 4–lag days. The current surface speeds in Schoenmakerskop were the lowest and varied directionally between north-north eastward and south-south eastward. The basic data requirements (i.e. SST/ UTR and ADCP time series) and the simplicity of the calculations make these indices a useful tool to apply to a large number of sites nationally and internationally, and to examine the generality of community and population-level responses to physical forcing. , Thesis (PhD) -- Faculty of Science, Journalsim and Media Studies, 2021
- Full Text:
- Date Issued: 2021-12
- Authors: Dlomo, Xolisa
- 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/10948/53607 , vital:45680
- Description: Upwelling, bay-scale currents, fronts and mixing in Algoa Bay and St Francis Bay occur over both short and long time periods. These physical ocean dynamics drive the temporal and spatial distribution of nutrients in the bays, there by influencing primary and secondary production. Thermal gradients and fronts are driven by the wind and open ocean influences, such as the Agulhas Current, daily and seasonal variations in solar radiation, long and short period waves, air-sea fluxes, coastal trapped waves and terrestrial freshwater inflow. These phenomena are poorly understood along this part of the coastline and were the focus of this study. I investigated the dominant temperature scales of variability in both bays, to determine which isotherm is best suited to describe temperature fluctuations and thermocline spatiotemporal variability in and between the two bays. I investigated upwelling spatiotemporal variability in the two bays and tested whether upwelling occurs at the opposite sides of the bays with a change in wind direction. Thereafter studied the occurrence and drivers of winter upwelling events. The wind-driven current spatiotemporal variability and correlations were investigated at the extremities of the two bays. The daily, intra-seasonal and yearly variation in temperature structures in Algoa Bay and St. Francis Bay were mainly driven by the local winds, coastal topography, and bathymetry. The most suitable isotherm to describe thermal fluctuations and variability in Algoa Bay shallower sites was 16.5 °C and its mean depth was 16.2 m. The best isotherm for the deeper sites in Algoa Bay was 15.7 °C with a depth of 33.1 m. The average temperature and depth of the best isotherm to describe thermal fluctuations in St. Francis Bay for the shallower sites was15.80 °C and 16.83 m, and for the deeper sites it was 15.10 °C and 32.08 m. Algoa Bay showed an average cooling trend of -0.000172 °C per year, whereas in St. Francis Bay a warming average trend of 0.0188 °C per year was observed over the study period often and six years, respectively. The wind, Coriolis Effect and Ekman Transport were the main external forces that influenced upwelling throughout the year. Since the available mesoscale indices for upwelling intensity lack the resolution needed to characterize and compare inner-shelf upwelling regimes at small spatial scales, I developed a new local, quantitative index of thermal variability. Index calculations were based on hourly records of in site depth-averaged temperatures, measured at 6 sites in St. Francis Bay and at 8 sites in Algoa Bay. Using the Multivariate Upwelling Zone Index of Cooling (MUZIC) I found that Woody Cape and Blue Horizon Bay had the highest upwelling intensity in Algoa Bay and St. Francis Bay, respectively. The other sites were ordinated and ranked according to their upwelling rates and intensity. Evidence of wind-driven winter upwelling was found to be a common occurrence in both bays. There was no obvious current seasonality observed, however, strong spectral signals in the period of a weather band (4 –7 days) were present. Current structures were generally positively correlated with wind variations in both bays. Thus, when westerly/easterly winds blew the overall surface current direction was eastward/westward. I observed a pronounced current spatiotemporal variability that was driven by local winds. The Bird Island surface currents in Algoa Bay were strongly correlated at 0–lag day with the winds, however, in Cape Recife the strongest correlations were usually observed at 1–lag day highlighting the spatiotemporal influence of wind regimes on current structures in Algoa Bay. Bird Island current speeds were higher and had an obvious bimodal directional variation (south westward /north eastward) compared to Cape Recife currents, which generally had a slower current speed with a strong west-north westward direction. In St. Francis Bay, the Schoenmakerskop surface currents showed weak positive correlation with winds at 0–lag day, however, stronger negative correlations were observed at 4–lag days. The current surface speeds in Schoenmakerskop were the lowest and varied directionally between north-north eastward and south-south eastward. The basic data requirements (i.e. SST/ UTR and ADCP time series) and the simplicity of the calculations make these indices a useful tool to apply to a large number of sites nationally and internationally, and to examine the generality of community and population-level responses to physical forcing. , Thesis (PhD) -- Faculty of Science, Journalsim and Media Studies, 2021
- Full Text:
- Date Issued: 2021-12
Mangrove response to water level changes at the Nxaxo-Ngqusi and St Lucia Estuaries
- Authors: Julie, Corianna Lauren
- 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/10948/53644 , vital:45689
- Description: Water level variability within an estuary can vary as a function of tides (inundation frequency and duration) and rainfall, acting as one of the main determinants of mangrove growth, diversity, productivity, and distribution. Understanding how mangroves respond in estuaries to water level variability provides baseline information which can be used to predict future changes in mangrove growth and distribution in response to this driver This study measured mangrove characteristics (growth, structure, and areal extent) in two estuaries that differed in tidal setting, and thus water variability; the Nxaxo-Ngqusi and St Lucia estuaries, South Africa. These estuaries are part of a long-term monitoring programme (2010 - 2020) that has recorded mangrove responses to environmental changes. At the Nxaxo-Ngqusi Estuary, long-tem sea-level data (2003 – 2018) collected from the nearest tide gauge, and mangrove growth and areal extent were used to assess mangrove characteristics in a permanently open, micro tidal setting.Additionally, short-term water level data (August 2019 – September 2020), measured with in situ loggers, and sediment input at different sites within the mangrove forest, were also measured. Data was collected along the main channel sites, and at previously set up cattle exclusion plots ( browsed and non-browsed sites set to establish the effect of cattle browsing on mangroves). Similarly, at the St Lucia Estuary, long term water level data (2004 – 2020) collected at the bridge in the lower reaches of the estuary by Ezemvelo KZN-Wildlife, and annual mangrove growth, structure and areal extent data were used to assess mangrove characteristics in an estuarine lake that undergoes cycles between hypersaline and freshwater-dominated states. The results showed that mangrove responses to water level changes are complex and depend on several factors such as estuary mouth dynamics, anthropogenic activities, and site-level environmental conditions. The first objective was to compare water level changes and mangrove structure (mangrove height, and pneumatophore characteristics such as height, density and % aerenchyma) and sediment input between different sites at each estuary. Mangrove growth was higher at sites where longer inundation and higher inundation frequency were recorded at the Nxaxo-Ngqusi Estuary. However,longer inundation periods under closed mouth conditions resulted in stunted growth and mangrove dieback at St Lucia Estuary. At the Nxaxo-Ngqusi Estuary, mangroves at the main channel sites, closer to the water’s edge, had an overall higher growth rate (2.8 – 45.9 cm yr-1) than the mangroves found at the browsed (0 – 25 cm yr-1) and non-browsed sites (0 – 25.3 cm yr-1) on the landward edge of the forest. The effect of cattle browsing at these sites forms part of a long-term monitoring programme and this disturbance could have also influenced the results. Mangrove growth rate was higher in years with more rainfall at all sites within the estuary. At the St Lucia Estuary, mangrove growth rate was highest (0.81 cm yr-1) at a lower mean water level range (0.13 – 1.72 m) between 2010 - 2015, and growth rate was lowest (1.3 cm yr-1) in higher mean water level range conditions (0.34 m – 2.18 m) between 2015 – 2020. When water levels increased by up to 1.1 m due to closed mouth conditions, this led to extensive mangrove dieback further upstream by 2015. The maximum tidal flooding depth and inundation period influenced pneumatophore structure (height, density, and % aerenchyma) at the Nxaxo-Ngqusi Estuary. Sediment accumulation was highest at sites with increased pneumatophore density, but accumulation rates at the Nxaxo-Ngqusi Estuary (0.4 – 0.7 g over a high tide lasting 4-5 hours) were low and did not lead to smothering of the pneumatophores. Total sediment accumulation was highest at sites that experienced greater flooding depths. Increased inundation at the St Lucia Estuary caused inundation stress which led to mangrove mortality. This is because these mangroves are found in a closed estuary where increased water levels lead to prolonged submergence of the pneumatophores. A decrease in mangrove area was recorded at both sites. Low rainfall coupled with cattle browsing caused a decrease in mangrove area of 22% between 2009 and 2019, particularly along the mangrove fringe area at the Nxaxo-Ngqusi Estuary. The mangroves at the St Lucia Estuary, however, experienced mangrove dieback at all sites, with Site 1 recording the greatest percentage decrease in area of 71.7 % (loss of 44.76 ha) between 2010 and 2020. This was related to the progressive increase of freshwater input and water level at St Lucia Estuary under closed mouth conditions. The years leading up to 2019 had peaks in water levels at the St Lucia Estuary, with the highest water level of 2.12 m in 2019 since 2002. As a consequence, there was increased reed growth, where reeds expanded by 58% (177 ha) due to the high influx of freshwater, and no tidal exchange, which occurred in conjunction with a loss of 60.% (42 ha) of the original mangrove extent at the St Lucia Estuary. This study shows that increased water level changes (inundation frequency and duration) at the Nxaxo-Ngqusi Estuary maintain healthy mangrove stands. This is in contrast to the St Lucia Estuary, where there was a loss of mangroves as a result of high water levels under closed mouth conditions. Mangrove growth and extent at the Nxaxo-Ngqusi Estuary fluctuated in response to drought, and trampling and browsing by livestock. Extensive inundation and lack of tidal exchange reduced mangrove growth and extent at the St Lucia Estuary, with mangrove dieback occurring at all sites. These two systems are representative of the dynamic conditions found in South African estuaries. These research findings suggest that the continuous effects of climate change on estuarine habitats could result in changes in estuary mouth dynamics, which could impact mangrove growth, structure, and extent. , Thesis (MSc) -- Faculty of Science, School of Environmental Sciences, 2021
- Full Text: false
- Date Issued: 2021-12
- Authors: Julie, Corianna Lauren
- 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/10948/53644 , vital:45689
- Description: Water level variability within an estuary can vary as a function of tides (inundation frequency and duration) and rainfall, acting as one of the main determinants of mangrove growth, diversity, productivity, and distribution. Understanding how mangroves respond in estuaries to water level variability provides baseline information which can be used to predict future changes in mangrove growth and distribution in response to this driver This study measured mangrove characteristics (growth, structure, and areal extent) in two estuaries that differed in tidal setting, and thus water variability; the Nxaxo-Ngqusi and St Lucia estuaries, South Africa. These estuaries are part of a long-term monitoring programme (2010 - 2020) that has recorded mangrove responses to environmental changes. At the Nxaxo-Ngqusi Estuary, long-tem sea-level data (2003 – 2018) collected from the nearest tide gauge, and mangrove growth and areal extent were used to assess mangrove characteristics in a permanently open, micro tidal setting.Additionally, short-term water level data (August 2019 – September 2020), measured with in situ loggers, and sediment input at different sites within the mangrove forest, were also measured. Data was collected along the main channel sites, and at previously set up cattle exclusion plots ( browsed and non-browsed sites set to establish the effect of cattle browsing on mangroves). Similarly, at the St Lucia Estuary, long term water level data (2004 – 2020) collected at the bridge in the lower reaches of the estuary by Ezemvelo KZN-Wildlife, and annual mangrove growth, structure and areal extent data were used to assess mangrove characteristics in an estuarine lake that undergoes cycles between hypersaline and freshwater-dominated states. The results showed that mangrove responses to water level changes are complex and depend on several factors such as estuary mouth dynamics, anthropogenic activities, and site-level environmental conditions. The first objective was to compare water level changes and mangrove structure (mangrove height, and pneumatophore characteristics such as height, density and % aerenchyma) and sediment input between different sites at each estuary. Mangrove growth was higher at sites where longer inundation and higher inundation frequency were recorded at the Nxaxo-Ngqusi Estuary. However,longer inundation periods under closed mouth conditions resulted in stunted growth and mangrove dieback at St Lucia Estuary. At the Nxaxo-Ngqusi Estuary, mangroves at the main channel sites, closer to the water’s edge, had an overall higher growth rate (2.8 – 45.9 cm yr-1) than the mangroves found at the browsed (0 – 25 cm yr-1) and non-browsed sites (0 – 25.3 cm yr-1) on the landward edge of the forest. The effect of cattle browsing at these sites forms part of a long-term monitoring programme and this disturbance could have also influenced the results. Mangrove growth rate was higher in years with more rainfall at all sites within the estuary. At the St Lucia Estuary, mangrove growth rate was highest (0.81 cm yr-1) at a lower mean water level range (0.13 – 1.72 m) between 2010 - 2015, and growth rate was lowest (1.3 cm yr-1) in higher mean water level range conditions (0.34 m – 2.18 m) between 2015 – 2020. When water levels increased by up to 1.1 m due to closed mouth conditions, this led to extensive mangrove dieback further upstream by 2015. The maximum tidal flooding depth and inundation period influenced pneumatophore structure (height, density, and % aerenchyma) at the Nxaxo-Ngqusi Estuary. Sediment accumulation was highest at sites with increased pneumatophore density, but accumulation rates at the Nxaxo-Ngqusi Estuary (0.4 – 0.7 g over a high tide lasting 4-5 hours) were low and did not lead to smothering of the pneumatophores. Total sediment accumulation was highest at sites that experienced greater flooding depths. Increased inundation at the St Lucia Estuary caused inundation stress which led to mangrove mortality. This is because these mangroves are found in a closed estuary where increased water levels lead to prolonged submergence of the pneumatophores. A decrease in mangrove area was recorded at both sites. Low rainfall coupled with cattle browsing caused a decrease in mangrove area of 22% between 2009 and 2019, particularly along the mangrove fringe area at the Nxaxo-Ngqusi Estuary. The mangroves at the St Lucia Estuary, however, experienced mangrove dieback at all sites, with Site 1 recording the greatest percentage decrease in area of 71.7 % (loss of 44.76 ha) between 2010 and 2020. This was related to the progressive increase of freshwater input and water level at St Lucia Estuary under closed mouth conditions. The years leading up to 2019 had peaks in water levels at the St Lucia Estuary, with the highest water level of 2.12 m in 2019 since 2002. As a consequence, there was increased reed growth, where reeds expanded by 58% (177 ha) due to the high influx of freshwater, and no tidal exchange, which occurred in conjunction with a loss of 60.% (42 ha) of the original mangrove extent at the St Lucia Estuary. This study shows that increased water level changes (inundation frequency and duration) at the Nxaxo-Ngqusi Estuary maintain healthy mangrove stands. This is in contrast to the St Lucia Estuary, where there was a loss of mangroves as a result of high water levels under closed mouth conditions. Mangrove growth and extent at the Nxaxo-Ngqusi Estuary fluctuated in response to drought, and trampling and browsing by livestock. Extensive inundation and lack of tidal exchange reduced mangrove growth and extent at the St Lucia Estuary, with mangrove dieback occurring at all sites. These two systems are representative of the dynamic conditions found in South African estuaries. These research findings suggest that the continuous effects of climate change on estuarine habitats could result in changes in estuary mouth dynamics, which could impact mangrove growth, structure, and extent. , Thesis (MSc) -- Faculty of Science, School of Environmental Sciences, 2021
- Full Text: false
- Date Issued: 2021-12
Coordination polymers for denitrogenation of fuel oils
- Authors: Dembaremba, Tendai O
- 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/10948/53630 , vital:45682
- Description: In this thesis, we present adsorptive removal of nitrogen-containing compounds from fuel oil as an alternative to complement conventional hydrotreatment to obtain ultra-low sulfur and nitrogen levels. This is in cognizance of the challenges nitrogen-containing compounds pose to the hydrotreatment process, particularly their inhibition and/or poisoning of the catalysts used in the process, of which basic nitrogen-containing compounds are the major culprits. Selectivity is the biggest challenge for adsorptive removal of nitrogen-containing compounds. We explore reticular synthesis of metal organic frameworks and the use of coordinatively unsaturated metal sites in 1-dimensional coordination polymers to achieve good selectivity for nitrogen-containing compounds. In the first part of the thesis, reticular synthesis of metal organic frameworks to control the size of the cavity, and strategically use the linkers and metal centres was envisaged. In this work we explored variation of the metal centres in the secondary building units (SBUs of the MOFs as the first step to the testing and implementation of the design strategies. Carbazole, representing carbazoles which the major compounds that remain in hydrotreated fuel, was the target compound. Four MOFs of zinc (Zn-CDC-bpe), copper (Cu-CDC-bpe), nickel (Ni-CDC-bpe) and cobalt (Co-CDC-bpe) based on the formation of a dinuclear metal paddlewheel SBUs with the ligand 9H-Carbazole-3,6-dicarboxylic acid (H2CDC) and occupation of the axial positions of the paddlewheel by 1,2-Bis(4-pyridyl)ethane (bpe) to form porous networks were synthesized. A fifth MOF containing only CDC which forms a [Zn4O(O2C-R)5(O2HC-R)] SBU was also synthesized (Zn-CDC). The ligand H2CDC was inspired by the possibility of improving selectivity for carbazole via π–π interactions through the more preferred parallel-offset stacking as well as the possibility for further substitution of the carbazole N-H to add groups that improve selectivity. The sizes of the MOF cavities can then be controlled by choosing different lengths of ligands analogous to 1,2-Bis(4-pyridyl)ethane (bpe), e.g. 4,4’-bipyridine and pyrazine. All the MOFs showed good selectivity of carbazole. The Zn-CDC MOF also had good selectivity for the basic nitrogen-containing compounds tested: quinoline, isoquinoline, quinaldine and 1-naphthylamine. Its uptake of carbazole was also slightly higher. This was attributed to the presence of an unsaturated Zn site in the SBU. Adsorption in all the MOFs was primarily due to physisorption. It was concluded that the role of the metal centre does not play a significant role in the adsorption of carbazole besides providing a template for reticular synthesis. , Thesis (PhD) -- Faculty of Science, School of Biomolecular and Chemical Sciences, 2021
- Full Text: false
- Date Issued: 2021-12
- Authors: Dembaremba, Tendai O
- 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/10948/53630 , vital:45682
- Description: In this thesis, we present adsorptive removal of nitrogen-containing compounds from fuel oil as an alternative to complement conventional hydrotreatment to obtain ultra-low sulfur and nitrogen levels. This is in cognizance of the challenges nitrogen-containing compounds pose to the hydrotreatment process, particularly their inhibition and/or poisoning of the catalysts used in the process, of which basic nitrogen-containing compounds are the major culprits. Selectivity is the biggest challenge for adsorptive removal of nitrogen-containing compounds. We explore reticular synthesis of metal organic frameworks and the use of coordinatively unsaturated metal sites in 1-dimensional coordination polymers to achieve good selectivity for nitrogen-containing compounds. In the first part of the thesis, reticular synthesis of metal organic frameworks to control the size of the cavity, and strategically use the linkers and metal centres was envisaged. In this work we explored variation of the metal centres in the secondary building units (SBUs of the MOFs as the first step to the testing and implementation of the design strategies. Carbazole, representing carbazoles which the major compounds that remain in hydrotreated fuel, was the target compound. Four MOFs of zinc (Zn-CDC-bpe), copper (Cu-CDC-bpe), nickel (Ni-CDC-bpe) and cobalt (Co-CDC-bpe) based on the formation of a dinuclear metal paddlewheel SBUs with the ligand 9H-Carbazole-3,6-dicarboxylic acid (H2CDC) and occupation of the axial positions of the paddlewheel by 1,2-Bis(4-pyridyl)ethane (bpe) to form porous networks were synthesized. A fifth MOF containing only CDC which forms a [Zn4O(O2C-R)5(O2HC-R)] SBU was also synthesized (Zn-CDC). The ligand H2CDC was inspired by the possibility of improving selectivity for carbazole via π–π interactions through the more preferred parallel-offset stacking as well as the possibility for further substitution of the carbazole N-H to add groups that improve selectivity. The sizes of the MOF cavities can then be controlled by choosing different lengths of ligands analogous to 1,2-Bis(4-pyridyl)ethane (bpe), e.g. 4,4’-bipyridine and pyrazine. All the MOFs showed good selectivity of carbazole. The Zn-CDC MOF also had good selectivity for the basic nitrogen-containing compounds tested: quinoline, isoquinoline, quinaldine and 1-naphthylamine. Its uptake of carbazole was also slightly higher. This was attributed to the presence of an unsaturated Zn site in the SBU. Adsorption in all the MOFs was primarily due to physisorption. It was concluded that the role of the metal centre does not play a significant role in the adsorption of carbazole besides providing a template for reticular synthesis. , Thesis (PhD) -- Faculty of Science, School of Biomolecular and Chemical Sciences, 2021
- Full Text: false
- Date Issued: 2021-12
Optimization of liposomes for enhanced stability against degradation by gastrointestinal fluid content
- Authors: Scholtz, Carla Chleo
- 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/10948/54117 , vital:46305
- Description: Motivation: Liposomes are nanoparticulate carriers consisting of a hydrophobic bilayer and a hydrophilic core. Their application as drug carrier systems arises from their unique physiochemical structure, biocompatibility and biodegradability. Their biphasic nature is significant in the delivery of peptide and protein drug molecules as it is thus able to encompass both hydrophobic and hydrophilic molecules. Liposomes are actively being used for drug delivery intravenously. These formulations have been successful in reducing side effects and improving therapeutic efficacy. However, the intravenous route poses many challenges and is not the preferred route of administration amongst patients. The oral route of administration is non-invasive, and administration is of ease, therefore it is the preferred route of administration amongst patients, especially those with complex medicine regimes. Problem: The gastrointestinal tract is a harsh environment. In order for liposomes to maintain their integrity during their course they require a level of stability against gastric and intestinal fluids and its associated constituents such as gastric and pancreatic enzymes, low pH and bile acid. Methodology: Based on recommendations extrapolated from literature, the incorporation of a bile salt, sodium glycocholate, into liposomes in conjunction with coating the surface with chitosan was selected as the optimization strategies to enhance the stability of liposomes against degradation in the gastrointestinal tract. Bilosomes with encapsulated calce in were produced using the thin-film hydration method and coated with chitosan. An in vitrocalce in release assay was conducted in simulated gastric and intestinal fluids which presented with in vivo conditions in terms of pH and enzymes and additional constituents such as a bile salt. Stability was determined by the extent of digestion within the simulated fluids with time. Results: Characterization results suggested that the addition of chitosan and sodium glycocholate to the liposomal formulation has significant effects on the physiochemical properties. The colloidal dispersions could not retain their stability during storage which was noticeable during HRTEM. Despite optimization of the liposomes, in vitro studies showed significant release in both simulated gastric and intestinal fluids, with majority release seen in the presence of pepsin and pancreatic, at low pH and in the presence of bile acid. , Thesis (MSc) -- Faculty of Science, School of Computer Science, Mathematics, Physics and Statistics, 2021
- Full Text:
- Date Issued: 2021-12
- Authors: Scholtz, Carla Chleo
- 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/10948/54117 , vital:46305
- Description: Motivation: Liposomes are nanoparticulate carriers consisting of a hydrophobic bilayer and a hydrophilic core. Their application as drug carrier systems arises from their unique physiochemical structure, biocompatibility and biodegradability. Their biphasic nature is significant in the delivery of peptide and protein drug molecules as it is thus able to encompass both hydrophobic and hydrophilic molecules. Liposomes are actively being used for drug delivery intravenously. These formulations have been successful in reducing side effects and improving therapeutic efficacy. However, the intravenous route poses many challenges and is not the preferred route of administration amongst patients. The oral route of administration is non-invasive, and administration is of ease, therefore it is the preferred route of administration amongst patients, especially those with complex medicine regimes. Problem: The gastrointestinal tract is a harsh environment. In order for liposomes to maintain their integrity during their course they require a level of stability against gastric and intestinal fluids and its associated constituents such as gastric and pancreatic enzymes, low pH and bile acid. Methodology: Based on recommendations extrapolated from literature, the incorporation of a bile salt, sodium glycocholate, into liposomes in conjunction with coating the surface with chitosan was selected as the optimization strategies to enhance the stability of liposomes against degradation in the gastrointestinal tract. Bilosomes with encapsulated calce in were produced using the thin-film hydration method and coated with chitosan. An in vitrocalce in release assay was conducted in simulated gastric and intestinal fluids which presented with in vivo conditions in terms of pH and enzymes and additional constituents such as a bile salt. Stability was determined by the extent of digestion within the simulated fluids with time. Results: Characterization results suggested that the addition of chitosan and sodium glycocholate to the liposomal formulation has significant effects on the physiochemical properties. The colloidal dispersions could not retain their stability during storage which was noticeable during HRTEM. Despite optimization of the liposomes, in vitro studies showed significant release in both simulated gastric and intestinal fluids, with majority release seen in the presence of pepsin and pancreatic, at low pH and in the presence of bile acid. , Thesis (MSc) -- Faculty of Science, School of Computer Science, Mathematics, Physics and Statistics, 2021
- Full Text:
- Date Issued: 2021-12
Perceptions of small-scale vegetable farmers on drought mitigation strategies in the Amathole District Municipality of the Eastern Cape Province
- Authors: Dingiswayo, Xolisile
- 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/10948/53676 , vital:45686
- Description: The present study aimed to investigate perceptions of small-scale vegetable farmers on drought mitigation strategies in the Amathole District Municipality of the Eastern Cape Province. The research objective was to investigate what small-scale vegetable farmers’ perceptions and readiness are in terms of strategies to cope with drought conditions. The study was conducted within the Mbashe, Mnquma, Amahlathi and Great Kei local municipalities of the Eastern Cape. Primary data collection was conducted among 44 small-scale vegetable farmers of the Amathole municipal district. These are farmers who receive social support from the government, are registered with the Department of Rural Development and Agrarian Reform and contribute to the fight against food insecurity in the Amathole district. The primary data was also collected from 13 agricultural extension officers with high experience in advising small-scale farmers residing in the Amathole district. Data collection took place in various local municipalities under Amathole District Municipality, namely: Mbashe, Mnquma, Amahlathi and Great Kei. A multi-method approach was adopted in this study as an appropriate technique to create an improved quality of research which eliminates the deep-rooted bias to either qualitative or quantitative methods alone. A self-administered questionnaires with both closed and open-ended questions – one for the small-scale farmer survey and the second for the extension officer survey – was employed as data collection instrument. The demographic characteristics of small-scale vegetable farmers in the survey area indicated that the present majority of farmers are married male Xhosa farmers between the ages of 56 and 65 years old, with a secondary level of education. The majority of the farmers are typically resource-poor − which implies that the added menace of drought poses the risk that small-scale vegetable farming could decline to mere subsistence level or worse. Drought was found to be a major problem in Mbashe, Mnquma, Amahlathi and Great Kei local municipalities within the Amathole municipal district, with an acute impact on farmers’ production and generation of income. From the data, it emerged that farmers are not sufficiently informed about and do not receive specific training in drought mitigation strategies. Farmers rely on drought alleviation methods but there is a lack of adaptive strategies and timely, long-term ii state intervention. Being resource-poor, these small-scale producers are reliant on natural resources – notably water for irrigating crops. The study established further that there is neither the resources nor sufficient training by and involvement of the extension service. Farmers therefore rely on the use of drought coping mechanisms and drought mitigation techniques and on adapting their production systems. The information-sharing sessions recommended can assist in improving rural livelihoods and the productivity of small-scale vegetable farmers. The absence of engagement of youth in farming means that modern conservation and innovative farming techniques and systems are not implemented towards reducing the impacts of climate change − as well as revitalizing rural areas such Amathole. Access to education about drought, improved drought coping mechanisms and adaptive strategies should be created to facilitate an exchange of traditional and modern agricultural information. The development of infrastructure in rural communities and farming areas is another factor crucial to improving farming systems and operations in the Amathole municipal district. , Thesis (MSc) -- Faculty of Science, School of Natural Resource Management, 2021
- Full Text: false
- Date Issued: 2021-12
- Authors: Dingiswayo, Xolisile
- 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/10948/53676 , vital:45686
- Description: The present study aimed to investigate perceptions of small-scale vegetable farmers on drought mitigation strategies in the Amathole District Municipality of the Eastern Cape Province. The research objective was to investigate what small-scale vegetable farmers’ perceptions and readiness are in terms of strategies to cope with drought conditions. The study was conducted within the Mbashe, Mnquma, Amahlathi and Great Kei local municipalities of the Eastern Cape. Primary data collection was conducted among 44 small-scale vegetable farmers of the Amathole municipal district. These are farmers who receive social support from the government, are registered with the Department of Rural Development and Agrarian Reform and contribute to the fight against food insecurity in the Amathole district. The primary data was also collected from 13 agricultural extension officers with high experience in advising small-scale farmers residing in the Amathole district. Data collection took place in various local municipalities under Amathole District Municipality, namely: Mbashe, Mnquma, Amahlathi and Great Kei. A multi-method approach was adopted in this study as an appropriate technique to create an improved quality of research which eliminates the deep-rooted bias to either qualitative or quantitative methods alone. A self-administered questionnaires with both closed and open-ended questions – one for the small-scale farmer survey and the second for the extension officer survey – was employed as data collection instrument. The demographic characteristics of small-scale vegetable farmers in the survey area indicated that the present majority of farmers are married male Xhosa farmers between the ages of 56 and 65 years old, with a secondary level of education. The majority of the farmers are typically resource-poor − which implies that the added menace of drought poses the risk that small-scale vegetable farming could decline to mere subsistence level or worse. Drought was found to be a major problem in Mbashe, Mnquma, Amahlathi and Great Kei local municipalities within the Amathole municipal district, with an acute impact on farmers’ production and generation of income. From the data, it emerged that farmers are not sufficiently informed about and do not receive specific training in drought mitigation strategies. Farmers rely on drought alleviation methods but there is a lack of adaptive strategies and timely, long-term ii state intervention. Being resource-poor, these small-scale producers are reliant on natural resources – notably water for irrigating crops. The study established further that there is neither the resources nor sufficient training by and involvement of the extension service. Farmers therefore rely on the use of drought coping mechanisms and drought mitigation techniques and on adapting their production systems. The information-sharing sessions recommended can assist in improving rural livelihoods and the productivity of small-scale vegetable farmers. The absence of engagement of youth in farming means that modern conservation and innovative farming techniques and systems are not implemented towards reducing the impacts of climate change − as well as revitalizing rural areas such Amathole. Access to education about drought, improved drought coping mechanisms and adaptive strategies should be created to facilitate an exchange of traditional and modern agricultural information. The development of infrastructure in rural communities and farming areas is another factor crucial to improving farming systems and operations in the Amathole municipal district. , Thesis (MSc) -- Faculty of Science, School of Natural Resource Management, 2021
- Full Text: false
- Date Issued: 2021-12