Movement ecology of a West African sciaenid fish, Argyrosomus coronus, in southern Angola
- Authors: Parkinson, Matthew Cameron
- Date: 2023-10-13
- Subjects: Uncatalogued
- Language: English
- Type: Academic theses , Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/432203 , vital:72851 , DOI 10.21504/10962/432203
- Description: Argyrosomus coronus is a large sciaenid species with a primary distribution between Cape Frio, in Namibia, and Luanda, in Angola, where it exists as a panmictic stock. Early juveniles (< 300 mm TL) occur on muddy offshore substrata (50–80 m deep) and at one year of age they recruit into the inshore zone. Adults are thought to predominantly occur inshore. Spawning occurs in the species during late spring. The species is heavily targeted by the recreational, subsistence, artisanal and commercial fisheries as juveniles through to adults and there are signs of population decline with declines in catch per unit effort (CPUE) and maximum size. A basic understanding of their movement ecology has emerged from previous studies, based on conventional tagging (mark-recapture) and CPUE monitoring from a shore-based recreational fishery. Juveniles were thought to be resident, with larger fish undertaking long distance migration southward in the austral summer and returning during the austral winter. In addition to the fishery-related threats faced by the species, the southern Angolan region has been identified to be an ocean warming hotspot, and this has been linked to a southward distribution shift and the recent hybridisation of A. coronus with its congener A. inodorus, in Namibia. This study aims to expand the knowledge of the movement ecology of A. coronus and to interrogate our current understanding of the movement patterns of the species using passive acoustic telemetry. Passive acoustic receivers were deployed at three study sites, Flamingo, where all tagging occurred, which lies ~ 200 km north of the Angolan border with Namibia, is a relatively exposed stretch of coastline; Tombua Bay, which lies 30 km south of Flamingo, is a small, sheltered natural embayment; and Baia dos Tigres, which lies 100 km south of Tombua Bay, is a sheltered lagoon in the lee of an island ~ 10 km from the mainland. Tagging occurred in two batches, one year apart. In the first batch, sub-adults (n = 3) and adults (n = 17) were tagged and monitored for two years. In the second batch, juveniles (n = 7) and sub-adults (n = 3) were tagged and monitored for one year. The first objective of this thesis (Chapter 3) was to examine the spatio-temporal dynamics of A. coronus at a regional-level (across study sites, to investigate the prevalence of the longshore migration), and at a local-level (within a study site), and to categorise the movement behaviour of juveniles, sub-adults and adults. Traditional seasons were not used in this thesis, as the study region alternates between ‘warm’ periods (up to ~ 26 °C mean daily water temperature), when Angola Current water covers the area, and ‘cold’ periods (down to ~ 15 °C mean daily water temperature), when Benguela Current water covers the area. A high degree of residency of tagged fish to the Flamingo study site, where tagging was conducted, was found, with juveniles and sub-adults never being detected outside of the Flamingo study site. Five adults (29 %) were detected haphazardly for between one and 36 days at Tombua Bay, following which they were typically detected again at the Flamingo study site. No fish were ever detected at the southernmost site, Baia dos Tigres, suggesting that none migrated to Namibia. Within the Flamingo study site, adults were found to group at the inshore mid-region of the study site during ‘cold’ periods, dispersing again during ‘warm’ periods, when there was a concomitant offshore shift in their area use. This explained the absence of the species from catches in the shore-based recreational fishery during ‘warm’ periods. These results challenge previous migration hypotheses for the species. Therefore, longshore return migrations which were evident from previously conducted conventional tagging, are probably not the norm for the species, but likely occur at a low frequency. The species exhibited a high degree of residency to their tagging site, despite the drastic seasonal changes in water temperatures and station-keeping was the dominant behaviour across all life stages. The constrained area-use noted in this study, relative to the known distribution of the species, suggests that A. coronus exists as a metapopulation, consisting of a network of subpopulations interconnected by gene flow that is most likely facilitated during their pelagic egg and larval phase. The second objective of this thesis was to examine the group formation observed at the Flamingo study site during ‘cold’ periods (Chapter 4). While this grouping of individuals was found to be correlated with water temperature, it was unlikely to be a causal relationship, as the water temperature was not dissimilar to adjacent areas. The area where individuals were concentrated is known to frequently attract large shoals of their dominant prey, Sardinella aurita. While the timing of this group formation aligns with a pre-spawning period, no studies have assessed the existence of local spawning. A. coronus were, however, likely utilising an abundant prey source, during the important pre-spawning period, in order to build up energy reserves. Group formation is a common feature of sciaenids, but literature on the subject is restricted to spawning congregations. Fish are not only more vulnerable to capture during these periods but may also be disturbed during these potentially important social periods. The third objective of this thesis was to investigate the presence of sociality in the species (Chapter 5). Evidence for sociality during and outside the seasonal group formation was explored using network analyses. There was evidence for sociality, with several groups, characterized by co-locations among individuals, identified. While these groups were fluid through time, there was evidence of persistent sociality, with two individuals in particular being consistently co-located over the entire study period. Due to the persistent nature of sociality, group foraging is suggested as an explanation for this, with anecdotal evidence of coordinated hunting supporting this. Acoustic telemetry vastly improved the knowledge of the movement ecology of A. coronus. Despite their panmictic population genetic structure, they were found to be largely resident, likely occurring as a metapopulation across their distribution, with egg and larval dispersal likely the primary mechanism for maintaining panmixia. Evidence for sociality was also found, which was previously unexplored in the species. The persistent nature of social groupings throughout the year, suggests that it may be linked with group foraging and is supported by anecdotal evidence of coordinated hunting by the species. While this study highlights the value of acoustic telemetry in studying movement ecology, it also shows the importance of drawing on multiple methods to fully understand a species’ spatial ecology, including mark-recapture, population genetics, and fishery catch and effort data. , Thesis (PhD) -- Faculty of Science, Ichthyology and Fisheries Science, 2023
- Full Text:
- Date Issued: 2023-10-13
- Authors: Parkinson, Matthew Cameron
- Date: 2023-10-13
- Subjects: Uncatalogued
- Language: English
- Type: Academic theses , Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/432203 , vital:72851 , DOI 10.21504/10962/432203
- Description: Argyrosomus coronus is a large sciaenid species with a primary distribution between Cape Frio, in Namibia, and Luanda, in Angola, where it exists as a panmictic stock. Early juveniles (< 300 mm TL) occur on muddy offshore substrata (50–80 m deep) and at one year of age they recruit into the inshore zone. Adults are thought to predominantly occur inshore. Spawning occurs in the species during late spring. The species is heavily targeted by the recreational, subsistence, artisanal and commercial fisheries as juveniles through to adults and there are signs of population decline with declines in catch per unit effort (CPUE) and maximum size. A basic understanding of their movement ecology has emerged from previous studies, based on conventional tagging (mark-recapture) and CPUE monitoring from a shore-based recreational fishery. Juveniles were thought to be resident, with larger fish undertaking long distance migration southward in the austral summer and returning during the austral winter. In addition to the fishery-related threats faced by the species, the southern Angolan region has been identified to be an ocean warming hotspot, and this has been linked to a southward distribution shift and the recent hybridisation of A. coronus with its congener A. inodorus, in Namibia. This study aims to expand the knowledge of the movement ecology of A. coronus and to interrogate our current understanding of the movement patterns of the species using passive acoustic telemetry. Passive acoustic receivers were deployed at three study sites, Flamingo, where all tagging occurred, which lies ~ 200 km north of the Angolan border with Namibia, is a relatively exposed stretch of coastline; Tombua Bay, which lies 30 km south of Flamingo, is a small, sheltered natural embayment; and Baia dos Tigres, which lies 100 km south of Tombua Bay, is a sheltered lagoon in the lee of an island ~ 10 km from the mainland. Tagging occurred in two batches, one year apart. In the first batch, sub-adults (n = 3) and adults (n = 17) were tagged and monitored for two years. In the second batch, juveniles (n = 7) and sub-adults (n = 3) were tagged and monitored for one year. The first objective of this thesis (Chapter 3) was to examine the spatio-temporal dynamics of A. coronus at a regional-level (across study sites, to investigate the prevalence of the longshore migration), and at a local-level (within a study site), and to categorise the movement behaviour of juveniles, sub-adults and adults. Traditional seasons were not used in this thesis, as the study region alternates between ‘warm’ periods (up to ~ 26 °C mean daily water temperature), when Angola Current water covers the area, and ‘cold’ periods (down to ~ 15 °C mean daily water temperature), when Benguela Current water covers the area. A high degree of residency of tagged fish to the Flamingo study site, where tagging was conducted, was found, with juveniles and sub-adults never being detected outside of the Flamingo study site. Five adults (29 %) were detected haphazardly for between one and 36 days at Tombua Bay, following which they were typically detected again at the Flamingo study site. No fish were ever detected at the southernmost site, Baia dos Tigres, suggesting that none migrated to Namibia. Within the Flamingo study site, adults were found to group at the inshore mid-region of the study site during ‘cold’ periods, dispersing again during ‘warm’ periods, when there was a concomitant offshore shift in their area use. This explained the absence of the species from catches in the shore-based recreational fishery during ‘warm’ periods. These results challenge previous migration hypotheses for the species. Therefore, longshore return migrations which were evident from previously conducted conventional tagging, are probably not the norm for the species, but likely occur at a low frequency. The species exhibited a high degree of residency to their tagging site, despite the drastic seasonal changes in water temperatures and station-keeping was the dominant behaviour across all life stages. The constrained area-use noted in this study, relative to the known distribution of the species, suggests that A. coronus exists as a metapopulation, consisting of a network of subpopulations interconnected by gene flow that is most likely facilitated during their pelagic egg and larval phase. The second objective of this thesis was to examine the group formation observed at the Flamingo study site during ‘cold’ periods (Chapter 4). While this grouping of individuals was found to be correlated with water temperature, it was unlikely to be a causal relationship, as the water temperature was not dissimilar to adjacent areas. The area where individuals were concentrated is known to frequently attract large shoals of their dominant prey, Sardinella aurita. While the timing of this group formation aligns with a pre-spawning period, no studies have assessed the existence of local spawning. A. coronus were, however, likely utilising an abundant prey source, during the important pre-spawning period, in order to build up energy reserves. Group formation is a common feature of sciaenids, but literature on the subject is restricted to spawning congregations. Fish are not only more vulnerable to capture during these periods but may also be disturbed during these potentially important social periods. The third objective of this thesis was to investigate the presence of sociality in the species (Chapter 5). Evidence for sociality during and outside the seasonal group formation was explored using network analyses. There was evidence for sociality, with several groups, characterized by co-locations among individuals, identified. While these groups were fluid through time, there was evidence of persistent sociality, with two individuals in particular being consistently co-located over the entire study period. Due to the persistent nature of sociality, group foraging is suggested as an explanation for this, with anecdotal evidence of coordinated hunting supporting this. Acoustic telemetry vastly improved the knowledge of the movement ecology of A. coronus. Despite their panmictic population genetic structure, they were found to be largely resident, likely occurring as a metapopulation across their distribution, with egg and larval dispersal likely the primary mechanism for maintaining panmixia. Evidence for sociality was also found, which was previously unexplored in the species. The persistent nature of social groupings throughout the year, suggests that it may be linked with group foraging and is supported by anecdotal evidence of coordinated hunting by the species. While this study highlights the value of acoustic telemetry in studying movement ecology, it also shows the importance of drawing on multiple methods to fully understand a species’ spatial ecology, including mark-recapture, population genetics, and fishery catch and effort data. , Thesis (PhD) -- Faculty of Science, Ichthyology and Fisheries Science, 2023
- Full Text:
- Date Issued: 2023-10-13
Playing it back: audible traces in contemporary African art
- Authors: Panchia, Bhavisha Laximi
- Date: 2023-10-13
- Subjects: Uncatalogued
- Language: English
- Type: Academic theses , Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/432455 , vital:72872
- Description: Access restricted. Exptected release date 2025. , Thesis (PhD) -- Faculty of Humanities, Fine Art, 2023
- Full Text:
- Date Issued: 2023-10-13
- Authors: Panchia, Bhavisha Laximi
- Date: 2023-10-13
- Subjects: Uncatalogued
- Language: English
- Type: Academic theses , Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/432455 , vital:72872
- Description: Access restricted. Exptected release date 2025. , Thesis (PhD) -- Faculty of Humanities, Fine Art, 2023
- Full Text:
- Date Issued: 2023-10-13
Porphyrinoid dyes for photodynamic anticancer and antimicrobial therapy treatments
- Authors: Soy, Rodah Cheruto
- Date: 2023-10-13
- Subjects: Uncatalogued
- Language: English
- Type: Academic theses , Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/432252 , vital:72855 , DOI 10.21504/10962/432252
- Description: The search for alternative therapies and non-toxic photosensitizer drugs that can efficiently generate cytotoxic reactive oxygen species for biomedical applications, such as in alternative photodynamic therapy (PDT) for cancer treatment and photodynamic antimicrobial chemotherapy (PACT) for drug-resistant bacteria treatment is on the rise. Nevertheless, the lack of photosensitizer dyes that absorb light strongly within the therapeutic window (620−850 nm) that can locally target the tumor and bacterial cells and generate singlet oxygen efficiently are some of the main challenges in PDT and PACT treatment. This study sought to address the challenges that impede PDT and PACT from realizing their full potential by synthesizing a series of meso-aryltetrapyrrolic photosensitizer dyes that absorb light within the therapeutic window. These include meso-tetraarylporphyrin (Por), A3-type meso-triarylcorrole (Cor), meso-tetraarylchlorin (Chl), and N-confused meso-tetraarylporphyrin (NCP) dyes with 4-thiomethylphenyl (1), thien-3-yl (2), thien-2-yl (3), 5-bromo-thien-2-yl (4), 4-methoxyphenyl (5), 3-methoxyphenyl (6), 4-hydroxyphenyl (7) and 4-hydroxy-3-methoxyphenyl (8) meso-aryl rings. Por, Cor, Chl and NCP dyes and and their Ga(III), P(V), In(III) and/or Sn(IV) complexes with 1-8, 1-4, 5-8 and 5 meso-aryl rings were studied, along with two A2B-type Ga(III) meso-triarylcorroles with pentafluorophenyl rings at the A2 positions and 3,6-di-t-butyl-9H-carbazole (9) or N-butyl-4-carbazole (10) rings at the B position that were prepared in the laboratory of Prof. Xu Liang of Jiangsu University in the People’s Republic of China. The carbazole nitrogen of 10-GaCor was quaternized at Rhodes University with ethyl iodide to form a cationic species (10-GaCor-Q) for PDT and PACT activity studies. The structures of the synthesized dyes were confirmed using UV-visible absorption and 1H NMR spectroscopy, and MALDI-TOF-mass spectrometry. 1-4-InPor In(III) porphyrins, 1-4-PVCor, 1-4-GaCor A3 PV and GaIII corrole dyes were also conjugated to gold nanoparticles (AuNPs) and silver nanoparticles (AgNPs) via sulfur-gold and sulfur-silver affinities. The successful conjugation of the dyes onto the nanoparticles to form dye-AuNP or dye-AgNP nanoassemblies was confirmed using transmission electron microscopy (TEM), energy dispersive X-ray (EDX) spectroscopy, X-ray powered diffraction (XRD), and (X-ray photon spectroscopy) XPS. The photophysicochemical, photostability, and lipophilicity properties of the dyes and their PDT and PACT activities were investigated, and the structure-property relationships were analyzed. This was accomplished by analyzing the changes in the properties of the dyes due to the meso-aryl substituents, central ions, molecular symmetry, and heavy atom effects. Time-dependent-density functional theory (TD-DFT) calculations were also used to further probe the electronic and optical spectroscopic properties of the dyes. The analysis of the photophysicochemical, photostability, and lipophilicity data for the synthesized dyes demonstrated that there are inherent structure-property relationships for the dyes studied. The TD-DFT calculations also assisted in rationalizing the observed optical spectroscopic data for the dyes. The introduction of different meso-aryl substituents resulted in minor absorption spectral changes on the parent structures of the dyes due to their inductive and mesomeric effects, while the insertion of Ga(III), In(III), and Sn(IV) electropositive metal centers resulted in marked red shifts of the B bands due to favorable interactions with the porphyrin or porphyrinoid ligand core. The lower symmetries of the corrole, chlorin, and N-confused porphyrin dyes resulted in enhanced absorption properties within the therapeutic window relative to porphyrins. The heavy atom effect from the Ga(III), In(III), and Sn(IV) central ions, the meso-aryl groups, and the external heavy atom effect from the AuNPs and AgNPs significantly reduced the fluorescence quantum yield values of the dyes resulting in high singlet oxygen quantum yields. The dye complexes also exhibited properly balanced lipophilic properties and high photostabilities. The P(V) ion of the A3 PV corrole dyes reduced the aggregation effects, enhanced cellular uptake, and lowered the lipophilicity values relative to the A3 GaIII corrole dyes. The porphyrin and porphyrinoid complexes studied exhibited relatively low in vitro dark cytotoxicity toward MCF-7 cancer cells, which is enhanced for AuNP nanoconjugates of 1-InPor, 1-3-PVCor, and 1-3-GaCor. The dyes also have low in vitro dark cytotoxicity toward planktonic and biofilm cells of S. aureus and E. coli. The complexes also exhibited favorable PDT and PACT activities toward MCF-7 cancer cells, and planktonic and biofilm S. aureus and E. coli bacteria due to their high singlet oxygen quantum yields. AuNP and AgNP nanoconjugates of 1-4-InPor, 1-4-PVCor, and 1-4-GaCor exhibited enhanced PDT and PACT activities due to the favorable synergistic effects of nanoparticles. The PDT and PACT activities of A3 PV corrole dyes and the nanoconjugates of 1-4-PVCor are slightly higher than those of A3-type GaIII corroles and their nanoconjugates due to decreased aggregation effects and enhanced PS drug uptake. The cationic 10-GaCor-Q species also exhibit favorable PDT and PACT activities in contrast to the neutral 9-10-GaCor dyes due to enhanced PS drug penetration into the tumor or bacteria cells. The complexes also exhibited high Log10 reduction values for planktonic S. aureus suggesting that the dyes are highly efficient PS dyes. The activities of the complexes toward planktonic E. coli bacteria are moderate except for 10-GaCor-Q, 2-4-PVCor-AgNPs, and 5-8-SnChl chlorins exhibiting relatively favorable activity with > 3 Log10 CFU.mL−1 values. The dyes also exhibit moderate activities toward the S. aureus and E. coli biofilm cells, which are lower than for the planktonic cells, as shown by their lower Log10 reduction values. The data demonstrate that the low symmetry corrole, chlorin, and N-confused porphyrin complexes that absorb light strongly within the therapeutic window have significantly enhanced PDT and PACT activities relative to their porphyrin analogs. , Thesis (PhD) -- Faculty of Science, Chemistry, 2023
- Full Text:
- Date Issued: 2023-10-13
- Authors: Soy, Rodah Cheruto
- Date: 2023-10-13
- Subjects: Uncatalogued
- Language: English
- Type: Academic theses , Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/432252 , vital:72855 , DOI 10.21504/10962/432252
- Description: The search for alternative therapies and non-toxic photosensitizer drugs that can efficiently generate cytotoxic reactive oxygen species for biomedical applications, such as in alternative photodynamic therapy (PDT) for cancer treatment and photodynamic antimicrobial chemotherapy (PACT) for drug-resistant bacteria treatment is on the rise. Nevertheless, the lack of photosensitizer dyes that absorb light strongly within the therapeutic window (620−850 nm) that can locally target the tumor and bacterial cells and generate singlet oxygen efficiently are some of the main challenges in PDT and PACT treatment. This study sought to address the challenges that impede PDT and PACT from realizing their full potential by synthesizing a series of meso-aryltetrapyrrolic photosensitizer dyes that absorb light within the therapeutic window. These include meso-tetraarylporphyrin (Por), A3-type meso-triarylcorrole (Cor), meso-tetraarylchlorin (Chl), and N-confused meso-tetraarylporphyrin (NCP) dyes with 4-thiomethylphenyl (1), thien-3-yl (2), thien-2-yl (3), 5-bromo-thien-2-yl (4), 4-methoxyphenyl (5), 3-methoxyphenyl (6), 4-hydroxyphenyl (7) and 4-hydroxy-3-methoxyphenyl (8) meso-aryl rings. Por, Cor, Chl and NCP dyes and and their Ga(III), P(V), In(III) and/or Sn(IV) complexes with 1-8, 1-4, 5-8 and 5 meso-aryl rings were studied, along with two A2B-type Ga(III) meso-triarylcorroles with pentafluorophenyl rings at the A2 positions and 3,6-di-t-butyl-9H-carbazole (9) or N-butyl-4-carbazole (10) rings at the B position that were prepared in the laboratory of Prof. Xu Liang of Jiangsu University in the People’s Republic of China. The carbazole nitrogen of 10-GaCor was quaternized at Rhodes University with ethyl iodide to form a cationic species (10-GaCor-Q) for PDT and PACT activity studies. The structures of the synthesized dyes were confirmed using UV-visible absorption and 1H NMR spectroscopy, and MALDI-TOF-mass spectrometry. 1-4-InPor In(III) porphyrins, 1-4-PVCor, 1-4-GaCor A3 PV and GaIII corrole dyes were also conjugated to gold nanoparticles (AuNPs) and silver nanoparticles (AgNPs) via sulfur-gold and sulfur-silver affinities. The successful conjugation of the dyes onto the nanoparticles to form dye-AuNP or dye-AgNP nanoassemblies was confirmed using transmission electron microscopy (TEM), energy dispersive X-ray (EDX) spectroscopy, X-ray powered diffraction (XRD), and (X-ray photon spectroscopy) XPS. The photophysicochemical, photostability, and lipophilicity properties of the dyes and their PDT and PACT activities were investigated, and the structure-property relationships were analyzed. This was accomplished by analyzing the changes in the properties of the dyes due to the meso-aryl substituents, central ions, molecular symmetry, and heavy atom effects. Time-dependent-density functional theory (TD-DFT) calculations were also used to further probe the electronic and optical spectroscopic properties of the dyes. The analysis of the photophysicochemical, photostability, and lipophilicity data for the synthesized dyes demonstrated that there are inherent structure-property relationships for the dyes studied. The TD-DFT calculations also assisted in rationalizing the observed optical spectroscopic data for the dyes. The introduction of different meso-aryl substituents resulted in minor absorption spectral changes on the parent structures of the dyes due to their inductive and mesomeric effects, while the insertion of Ga(III), In(III), and Sn(IV) electropositive metal centers resulted in marked red shifts of the B bands due to favorable interactions with the porphyrin or porphyrinoid ligand core. The lower symmetries of the corrole, chlorin, and N-confused porphyrin dyes resulted in enhanced absorption properties within the therapeutic window relative to porphyrins. The heavy atom effect from the Ga(III), In(III), and Sn(IV) central ions, the meso-aryl groups, and the external heavy atom effect from the AuNPs and AgNPs significantly reduced the fluorescence quantum yield values of the dyes resulting in high singlet oxygen quantum yields. The dye complexes also exhibited properly balanced lipophilic properties and high photostabilities. The P(V) ion of the A3 PV corrole dyes reduced the aggregation effects, enhanced cellular uptake, and lowered the lipophilicity values relative to the A3 GaIII corrole dyes. The porphyrin and porphyrinoid complexes studied exhibited relatively low in vitro dark cytotoxicity toward MCF-7 cancer cells, which is enhanced for AuNP nanoconjugates of 1-InPor, 1-3-PVCor, and 1-3-GaCor. The dyes also have low in vitro dark cytotoxicity toward planktonic and biofilm cells of S. aureus and E. coli. The complexes also exhibited favorable PDT and PACT activities toward MCF-7 cancer cells, and planktonic and biofilm S. aureus and E. coli bacteria due to their high singlet oxygen quantum yields. AuNP and AgNP nanoconjugates of 1-4-InPor, 1-4-PVCor, and 1-4-GaCor exhibited enhanced PDT and PACT activities due to the favorable synergistic effects of nanoparticles. The PDT and PACT activities of A3 PV corrole dyes and the nanoconjugates of 1-4-PVCor are slightly higher than those of A3-type GaIII corroles and their nanoconjugates due to decreased aggregation effects and enhanced PS drug uptake. The cationic 10-GaCor-Q species also exhibit favorable PDT and PACT activities in contrast to the neutral 9-10-GaCor dyes due to enhanced PS drug penetration into the tumor or bacteria cells. The complexes also exhibited high Log10 reduction values for planktonic S. aureus suggesting that the dyes are highly efficient PS dyes. The activities of the complexes toward planktonic E. coli bacteria are moderate except for 10-GaCor-Q, 2-4-PVCor-AgNPs, and 5-8-SnChl chlorins exhibiting relatively favorable activity with > 3 Log10 CFU.mL−1 values. The dyes also exhibit moderate activities toward the S. aureus and E. coli biofilm cells, which are lower than for the planktonic cells, as shown by their lower Log10 reduction values. The data demonstrate that the low symmetry corrole, chlorin, and N-confused porphyrin complexes that absorb light strongly within the therapeutic window have significantly enhanced PDT and PACT activities relative to their porphyrin analogs. , Thesis (PhD) -- Faculty of Science, Chemistry, 2023
- Full Text:
- Date Issued: 2023-10-13
Prediction of mass spectra using an ab initio approach
- Authors: Novokoza, Yolanda
- Date: 2023-10-13
- Subjects: Uncatalogued
- Language: English
- Type: Academic theses , Doctoral theses , text
- Identifier: http://hdl.handle.net/${Handle} , vital:72818
- Description: Access restricted. Expected release date in 2025. , Thesis (PhD) -- Faculty of Science, Chemistry, 2023
- Full Text:
- Date Issued: 2023-10-13
- Authors: Novokoza, Yolanda
- Date: 2023-10-13
- Subjects: Uncatalogued
- Language: English
- Type: Academic theses , Doctoral theses , text
- Identifier: http://hdl.handle.net/${Handle} , vital:72818
- Description: Access restricted. Expected release date in 2025. , Thesis (PhD) -- Faculty of Science, Chemistry, 2023
- Full Text:
- Date Issued: 2023-10-13
Revisionist narratives: locating six Black artist-teachers onto the map of twentieth-century modern art in Zimbabwe
- Authors: Muvhuti, Tichapera Barnabas
- Date: 2023-10-13
- Subjects: Uncatalogued
- Language: English
- Type: Academic theses , Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/432444 , vital:72871 , DOI 10.21504/10962/432444
- Description: Job Kekana (1916-1995) was a South African sculptor and teacher who moved to Zimbabwe in 1944, where he founded the Kekana School of Art and Craft in the early 1960s. There were also a few Black Zimbabwean artist-teachers, namely, Sam Songo (1929-1977), Cornelius Manguma (b. 1935), Lazarus Khumalo (1930-2015), Joram Mariga (1927-2000) John Hlatywayo (b. 1928), who were either working with missionaries Canon Edward Paterson (1895-1974) and Father John Groeber (1903-1973) at the Cyrene and Serima workshops respectively and later on at the Mzilikazi Arts and Crafts Centre, or with Frank McEwen (1907- 1994) at the National Gallery school. This thesis examines the relative invisibility of Kekana and the selected Black artist-teachers in the dominant discourse of the history and development of modern art in Zimbabwe. Employing the biographical approach as a methodology, and modernism as an analytical tool and foregrounding African thinkers like Chika Okeke-Agulu Elizabeth Georgis, Emma Wolukau- Wanambwa and Salah Hassan, this research exposes the possible reasons for their exclusion from the canon, which are rooted in a gatekeeping culture shown by actors in the local art scene, including art historians and scholars, as well as cultural workers in institutions like the National Gallery of Zimbabwe who have not sufficiently questioned and possibly shaken the enshrined legacies of Paterson, Groeber and McEwen. Canons mostly tend to tell a story that privileges and excludes others from the art narrative of a nation. With the arrival of Frank McEwen on the scene in the late 1950s the stone sculpture tradition rose to prominence in such a way that it overshadowed other forms of art produced in the two mission schools or workshops at Serima and Cyrene. In the process, Kekana and his students at the Kekana School of Art and Craft were relegated to the peripheries of the canon as they carved in wood and tended to work in a more representational style. While there is literature acknowledging the role of the missionaries in laying the foundation of modern art in Zimbabwe, local artists-cum-teachers working with them are only recognised as a footnote on the nation’s map of modern art. Recognising that canons are always evolving and shifting, and without discrediting the work of the three mentioned expatriates – and to an extent that of Tom Blomefield of the Tengenenge Workshop – this thesis attempts to expand the canon by arguing for the inclusion of the critiqued overlooked six. Citing the efforts of researchers, scholars and curators in multicultural South Africa to bring the previously marginalised generation of Black modernists into the mainstream, this thesis demonstrates that it is possible to spotlight the narratives of the Black artists and teachers who continue to occupy peripheral space in the history of Zimbabwe. This comparative analysis is done bearing in mind the temptation of falling into the trap of glorifying ‘South African exceptionalism’. In analysing the Black artist-teachers’ contributions as a counter-narrative, this research proposes a more heterogeneous modernism and revisionist art history. , Thesis (PhD) -- Faculty of Humanities, Fine Art, 2023
- Full Text:
- Date Issued: 2023-10-13
- Authors: Muvhuti, Tichapera Barnabas
- Date: 2023-10-13
- Subjects: Uncatalogued
- Language: English
- Type: Academic theses , Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/432444 , vital:72871 , DOI 10.21504/10962/432444
- Description: Job Kekana (1916-1995) was a South African sculptor and teacher who moved to Zimbabwe in 1944, where he founded the Kekana School of Art and Craft in the early 1960s. There were also a few Black Zimbabwean artist-teachers, namely, Sam Songo (1929-1977), Cornelius Manguma (b. 1935), Lazarus Khumalo (1930-2015), Joram Mariga (1927-2000) John Hlatywayo (b. 1928), who were either working with missionaries Canon Edward Paterson (1895-1974) and Father John Groeber (1903-1973) at the Cyrene and Serima workshops respectively and later on at the Mzilikazi Arts and Crafts Centre, or with Frank McEwen (1907- 1994) at the National Gallery school. This thesis examines the relative invisibility of Kekana and the selected Black artist-teachers in the dominant discourse of the history and development of modern art in Zimbabwe. Employing the biographical approach as a methodology, and modernism as an analytical tool and foregrounding African thinkers like Chika Okeke-Agulu Elizabeth Georgis, Emma Wolukau- Wanambwa and Salah Hassan, this research exposes the possible reasons for their exclusion from the canon, which are rooted in a gatekeeping culture shown by actors in the local art scene, including art historians and scholars, as well as cultural workers in institutions like the National Gallery of Zimbabwe who have not sufficiently questioned and possibly shaken the enshrined legacies of Paterson, Groeber and McEwen. Canons mostly tend to tell a story that privileges and excludes others from the art narrative of a nation. With the arrival of Frank McEwen on the scene in the late 1950s the stone sculpture tradition rose to prominence in such a way that it overshadowed other forms of art produced in the two mission schools or workshops at Serima and Cyrene. In the process, Kekana and his students at the Kekana School of Art and Craft were relegated to the peripheries of the canon as they carved in wood and tended to work in a more representational style. While there is literature acknowledging the role of the missionaries in laying the foundation of modern art in Zimbabwe, local artists-cum-teachers working with them are only recognised as a footnote on the nation’s map of modern art. Recognising that canons are always evolving and shifting, and without discrediting the work of the three mentioned expatriates – and to an extent that of Tom Blomefield of the Tengenenge Workshop – this thesis attempts to expand the canon by arguing for the inclusion of the critiqued overlooked six. Citing the efforts of researchers, scholars and curators in multicultural South Africa to bring the previously marginalised generation of Black modernists into the mainstream, this thesis demonstrates that it is possible to spotlight the narratives of the Black artists and teachers who continue to occupy peripheral space in the history of Zimbabwe. This comparative analysis is done bearing in mind the temptation of falling into the trap of glorifying ‘South African exceptionalism’. In analysing the Black artist-teachers’ contributions as a counter-narrative, this research proposes a more heterogeneous modernism and revisionist art history. , Thesis (PhD) -- Faculty of Humanities, Fine Art, 2023
- Full Text:
- Date Issued: 2023-10-13
Screening isolation and biological characterization of antibacterial secondary metabolites from macrofauna endemic to the southern African coast
- Authors: Njanje, Idris
- Date: 2023-10-13
- Subjects: Uncatalogued
- Language: English
- Type: Academic theses , Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/431944 , vital:72817
- Description: Access restricted. Expected release date in 2025. , Thesis (PhD) -- Faculty of Science, Chemistry, 2023
- Full Text:
- Date Issued: 2023-10-13
- Authors: Njanje, Idris
- Date: 2023-10-13
- Subjects: Uncatalogued
- Language: English
- Type: Academic theses , Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/431944 , vital:72817
- Description: Access restricted. Expected release date in 2025. , Thesis (PhD) -- Faculty of Science, Chemistry, 2023
- Full Text:
- Date Issued: 2023-10-13
Seeing diplomatic constellations through diplomatic relations: an analysis of the positioning of Zimbabwe and the UK in Zimbabwean news articles
- Mvundura, Emaculate Musimeki
- Authors: Mvundura, Emaculate Musimeki
- Date: 2023-10-13
- Subjects: Uncatalogued
- Language: English
- Type: Academic theses , Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/432388 , vital:72866 , DOI 10.21504/10962/432389
- Description: This study examines the positioning of Zimbabwe and the United Kingdom (UK) in the language of news articles about diplomatic relations between the two countries published in two prominent Zimbabwean newspapers, The Herald and The Standard, between 2016 and 2020, using Systemic Functional Linguistics (SFL) and Legitimation Code Theory (LCT). Zimbabwe's present diplomatic discourses are a product of its colonial and post-independence history. This thesis places The Herald and The Standard within the larger context of the Zimbabwean media landscape as a state-owned and a privately owned newspaper, respectively. It contends that the two newspapers influence the positioning of Zimbabwe and the United Kingdom in public spheres where readers engage with the news concerning diplomatic ties. The research begins with a corpus-based examination of 42 news articles published between 2016 and 2020 in The Herald and The Standard. The investigation identified several angles through which Zimbabwe and the UK are positioned in the coverage. Zimbabwe is positioned through reference to its reform agenda, intentions for free and fair elections, and its diplomatic re-engagement drive. The UK is positioned as a source of development funding and new trade agreements, while improved diplomatic relations and the removal of restrictive measures against Zimbabwe are anticipated. Fine-grained analysis was conducted on four articles, two from each newspaper, selected to reflect the trends found in the corpus analysis. The fine-grained analyses showed how linguistic resources contributed to the positioning of the UK and Zimbabwe. Complementary analyses of these articles were conducted using LCT and SFL to describe how readers' knowledge of diplomatic relations is built using language in The Herald and The Standard. The study used the concepts of constellations and cosmologies from LCT to demonstrate how diplomatic knowledge is built in these news articles. In the articles, the constellations are related to policies such as Zimbabwe's reform agenda, people (diplomats and government officials) and moral judgments. Both newspapers contain both positive and negative positioning of Zimbabwe and the UK. However, The Standard is generally critical of removing the UK's sanctions on Zimbabwe and of the Zimbabwean government's reform agenda. Meanwhile, The Herald justifies Zimbabwe's Fast-track Land Reform Programme as resulting from Britain's refusal to fund a land redistribution programme as per the 1979 Lancaster House Agreement. The use of SFL's Appraisal framework helps to examine the linguistic resources used by The Herald and The Standard to describe the positioning of the two countries in relation to each other. Lexical strings help to establish diplomatic positioning in the news articles. These couple with Appraisal to accomplish individuation and affiliation. Affect and Judgement resources revealed the decisions taken by the UK to solve the conflict by encouraging the implementation of a reform agenda by Zimbabwe. Negative evaluation is consistently used to disalign with sanctions. The emerging patterns in the data show that diplomats representing the UK affiliate with Zimbabwe's stated economic and political reforms, and the government of Zimbabwe affiliates with the new trade agreement between Zimbabwe and the UK. At the same time, the UK diplomats individuate away from human rights abuses and the Fast-track Land Reform Programme. Affiliation strengthens confidence in diplomatic ties between Zimbabwe and the UK because the emphasis is placed on restoring them despite the conditions attached. The Herald and The Standard position Zimbabwe as a reformed country ready to implement policies to improve citizens' lives and as a country violating human rights and the rule of law. They position the UK as asserting power over Zimbabwe, willing to resolve the crisis through its foreign policy, and credited for assisting Zimbabwe. This strengthens re-engagement in diplomatic relations and commercial trade between the UK and Zimbabwe. In light of these findings, Zimbabweans are encouraged to cultivate an awareness that enables them to reflect on the challenges associated with diplomatic discourses and the implications for critically analysing the re-engagement initiative. They can promote re-engagement by being cognisant of specific values portrayed in The Herald and The Standard and challenging these values in the light of policy transformation to revive the relations between the two countries. The re-engagement process requires a transformation in Zimbabwe's modus operandi to improve the country's positioning in the diplomatic relations between it and the UK. , Thesis (PhD) -- Faculty of Humanities, Linguistics and Applied Language Studies, 2023
- Full Text:
- Date Issued: 2023-10-13
- Authors: Mvundura, Emaculate Musimeki
- Date: 2023-10-13
- Subjects: Uncatalogued
- Language: English
- Type: Academic theses , Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/432388 , vital:72866 , DOI 10.21504/10962/432389
- Description: This study examines the positioning of Zimbabwe and the United Kingdom (UK) in the language of news articles about diplomatic relations between the two countries published in two prominent Zimbabwean newspapers, The Herald and The Standard, between 2016 and 2020, using Systemic Functional Linguistics (SFL) and Legitimation Code Theory (LCT). Zimbabwe's present diplomatic discourses are a product of its colonial and post-independence history. This thesis places The Herald and The Standard within the larger context of the Zimbabwean media landscape as a state-owned and a privately owned newspaper, respectively. It contends that the two newspapers influence the positioning of Zimbabwe and the United Kingdom in public spheres where readers engage with the news concerning diplomatic ties. The research begins with a corpus-based examination of 42 news articles published between 2016 and 2020 in The Herald and The Standard. The investigation identified several angles through which Zimbabwe and the UK are positioned in the coverage. Zimbabwe is positioned through reference to its reform agenda, intentions for free and fair elections, and its diplomatic re-engagement drive. The UK is positioned as a source of development funding and new trade agreements, while improved diplomatic relations and the removal of restrictive measures against Zimbabwe are anticipated. Fine-grained analysis was conducted on four articles, two from each newspaper, selected to reflect the trends found in the corpus analysis. The fine-grained analyses showed how linguistic resources contributed to the positioning of the UK and Zimbabwe. Complementary analyses of these articles were conducted using LCT and SFL to describe how readers' knowledge of diplomatic relations is built using language in The Herald and The Standard. The study used the concepts of constellations and cosmologies from LCT to demonstrate how diplomatic knowledge is built in these news articles. In the articles, the constellations are related to policies such as Zimbabwe's reform agenda, people (diplomats and government officials) and moral judgments. Both newspapers contain both positive and negative positioning of Zimbabwe and the UK. However, The Standard is generally critical of removing the UK's sanctions on Zimbabwe and of the Zimbabwean government's reform agenda. Meanwhile, The Herald justifies Zimbabwe's Fast-track Land Reform Programme as resulting from Britain's refusal to fund a land redistribution programme as per the 1979 Lancaster House Agreement. The use of SFL's Appraisal framework helps to examine the linguistic resources used by The Herald and The Standard to describe the positioning of the two countries in relation to each other. Lexical strings help to establish diplomatic positioning in the news articles. These couple with Appraisal to accomplish individuation and affiliation. Affect and Judgement resources revealed the decisions taken by the UK to solve the conflict by encouraging the implementation of a reform agenda by Zimbabwe. Negative evaluation is consistently used to disalign with sanctions. The emerging patterns in the data show that diplomats representing the UK affiliate with Zimbabwe's stated economic and political reforms, and the government of Zimbabwe affiliates with the new trade agreement between Zimbabwe and the UK. At the same time, the UK diplomats individuate away from human rights abuses and the Fast-track Land Reform Programme. Affiliation strengthens confidence in diplomatic ties between Zimbabwe and the UK because the emphasis is placed on restoring them despite the conditions attached. The Herald and The Standard position Zimbabwe as a reformed country ready to implement policies to improve citizens' lives and as a country violating human rights and the rule of law. They position the UK as asserting power over Zimbabwe, willing to resolve the crisis through its foreign policy, and credited for assisting Zimbabwe. This strengthens re-engagement in diplomatic relations and commercial trade between the UK and Zimbabwe. In light of these findings, Zimbabweans are encouraged to cultivate an awareness that enables them to reflect on the challenges associated with diplomatic discourses and the implications for critically analysing the re-engagement initiative. They can promote re-engagement by being cognisant of specific values portrayed in The Herald and The Standard and challenging these values in the light of policy transformation to revive the relations between the two countries. The re-engagement process requires a transformation in Zimbabwe's modus operandi to improve the country's positioning in the diplomatic relations between it and the UK. , Thesis (PhD) -- Faculty of Humanities, Linguistics and Applied Language Studies, 2023
- Full Text:
- Date Issued: 2023-10-13
Silica supported sulfuric acid-catalysed one-pot processes for the synthesis of n-heterocycles
- Authors: Ndagano, Urbain Nshokano
- Date: 2023-10-13
- Subjects: Uncatalogued
- Language: English
- Type: Academic theses , Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/431921 , vital:72815
- Description: Access restricted. Expected release in 2025. , Thesis (PhD) -- Faculty of Science, Chemistry, 2023
- Full Text:
- Date Issued: 2023-10-13
- Authors: Ndagano, Urbain Nshokano
- Date: 2023-10-13
- Subjects: Uncatalogued
- Language: English
- Type: Academic theses , Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/431921 , vital:72815
- Description: Access restricted. Expected release in 2025. , Thesis (PhD) -- Faculty of Science, Chemistry, 2023
- Full Text:
- Date Issued: 2023-10-13
South African women’s experience of the decision, procedure and recovery from “feticide” and late termination of pregnancy due to the presence of severe fetal abnormality: women’s and health service providers’ perspectives
- Authors: Vorster, Angela Carol
- Date: 2023-10-13
- Subjects: Uncatalogued
- Language: English
- Type: Academic theses , Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/432359 , vital:72864 , DOI 10.21504/10962/432359
- Description: Routine antenatal care, including sonography and genetic testing, assist healthcare providers in identifying the presence of severe fetal abnormality. In countries where it is legal, the option to abort such a pregnancy may be presented to the pregnant person. When abortion takes place after the thirteenth week of gestation, it is generally referred to as a late termination of pregnancy and may entail the induction of labour or caesarean section. In cases where termination of the pregnancy is decided upon, and the gestation is further than 21 weeks and six days, the feticide procedure is recommended in order to ensure stillbirth. The feticide procedure entails the injection of potassium chloride directly into the fetal heart in order to ensure fetal demise. Existing literature on “feticide” and late termination of pregnancy (LTOP) owing to fetal abnormalities mostly takes a medical or psychological perspective in researching these procedures. Within the South African context, there are very few studies on feticide and LTOP, with none of these studies (to date – 8 January 2023) taking a feminist approach. This paucity of research that takes into account power relations, structural inequality and factors that affect decision-making and choice is one of the reasons that this study was undertaken. The main research question focused on in this study is: What are South African women’s experiences of feticide and late termination of pregnancy due to the presence of severe fetal abnormality, as related by the women themselves and the health service providers who perform the procedure or provide care? The sub-questions that initially drove the study were: How do the women relate their experience of the process of coming to the decision, undergoing and recovering from the procedure, and how do health service providers relate the experiences of these women? The methodological and theoretical framework employed in this research was a Feminist Social Constructionist approach to Grounded Theory. This reflexive, subjectivist, feminist lens encouraged awareness of the influence of gender, race, class and other structural and systemic factors on women’s experiences within the two healthcare systems. Data collection entailed semi-structured interviews conducted with 12 women, who had undergone feticide and LTOP procedures between one and five years prior to the interviews, in either the public or private healthcare system in South Africa. Semi-structured interviews were also conducted with 13 healthcare providers. The providers included medical specialists and participants from the fields of clinical psychology, genetic counselling and nursing and were employed in public or private healthcare in South Africa. Data relevant to public healthcare users and providers were collected from one tertiary (academic) public healthcare hospital and data regarding private healthcare users and providers were collected from across South Africa. Women’s constructions of their experiences of feticide and LTOP included stark contrasts between public and private healthcare users in South Africa, as well as women experiencing “no choice” and their voices being ignored or silenced. Healthcare providers’ constructions were frequently contradictory, referring to women as having freedom of choice and their needs largely prioritised within the healthcare system, while the providers within the public healthcare system relayed their own frustrations and emotional burden due to systemic failures. Findings from women and providers’ constructions were synthesised into a theoretical understanding of women’s experiences of feticide and LTOP in South Africa, which is grounded in, and emergent from, the data. Women’s experiences of feticide and LTOP in South Africa were conceptualised by framing the three phases of these experiences, namely the decision-making phase (I), undergoing the procedures and in-hospital recovery (phase II) and the recovery phase (III). The most prominent themes emerging in these phases included the schism between the public and private healthcare systems in South Africa, the lack of real choice women experience, as well as the silencing of women and providers with regard to feticide and LTOP. Underlying the three phases, and directly influencing the three prominent themes affecting women’s experiences, were the underlying and insidious structural inequality that undermined reproductive justice with regard to women’s decision-making, experiences of and recovery from feticide and LTOP. , Thesis (PhD) -- Faculty of Humanities, Psychology, 2023
- Full Text:
- Date Issued: 2023-10-13
- Authors: Vorster, Angela Carol
- Date: 2023-10-13
- Subjects: Uncatalogued
- Language: English
- Type: Academic theses , Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/432359 , vital:72864 , DOI 10.21504/10962/432359
- Description: Routine antenatal care, including sonography and genetic testing, assist healthcare providers in identifying the presence of severe fetal abnormality. In countries where it is legal, the option to abort such a pregnancy may be presented to the pregnant person. When abortion takes place after the thirteenth week of gestation, it is generally referred to as a late termination of pregnancy and may entail the induction of labour or caesarean section. In cases where termination of the pregnancy is decided upon, and the gestation is further than 21 weeks and six days, the feticide procedure is recommended in order to ensure stillbirth. The feticide procedure entails the injection of potassium chloride directly into the fetal heart in order to ensure fetal demise. Existing literature on “feticide” and late termination of pregnancy (LTOP) owing to fetal abnormalities mostly takes a medical or psychological perspective in researching these procedures. Within the South African context, there are very few studies on feticide and LTOP, with none of these studies (to date – 8 January 2023) taking a feminist approach. This paucity of research that takes into account power relations, structural inequality and factors that affect decision-making and choice is one of the reasons that this study was undertaken. The main research question focused on in this study is: What are South African women’s experiences of feticide and late termination of pregnancy due to the presence of severe fetal abnormality, as related by the women themselves and the health service providers who perform the procedure or provide care? The sub-questions that initially drove the study were: How do the women relate their experience of the process of coming to the decision, undergoing and recovering from the procedure, and how do health service providers relate the experiences of these women? The methodological and theoretical framework employed in this research was a Feminist Social Constructionist approach to Grounded Theory. This reflexive, subjectivist, feminist lens encouraged awareness of the influence of gender, race, class and other structural and systemic factors on women’s experiences within the two healthcare systems. Data collection entailed semi-structured interviews conducted with 12 women, who had undergone feticide and LTOP procedures between one and five years prior to the interviews, in either the public or private healthcare system in South Africa. Semi-structured interviews were also conducted with 13 healthcare providers. The providers included medical specialists and participants from the fields of clinical psychology, genetic counselling and nursing and were employed in public or private healthcare in South Africa. Data relevant to public healthcare users and providers were collected from one tertiary (academic) public healthcare hospital and data regarding private healthcare users and providers were collected from across South Africa. Women’s constructions of their experiences of feticide and LTOP included stark contrasts between public and private healthcare users in South Africa, as well as women experiencing “no choice” and their voices being ignored or silenced. Healthcare providers’ constructions were frequently contradictory, referring to women as having freedom of choice and their needs largely prioritised within the healthcare system, while the providers within the public healthcare system relayed their own frustrations and emotional burden due to systemic failures. Findings from women and providers’ constructions were synthesised into a theoretical understanding of women’s experiences of feticide and LTOP in South Africa, which is grounded in, and emergent from, the data. Women’s experiences of feticide and LTOP in South Africa were conceptualised by framing the three phases of these experiences, namely the decision-making phase (I), undergoing the procedures and in-hospital recovery (phase II) and the recovery phase (III). The most prominent themes emerging in these phases included the schism between the public and private healthcare systems in South Africa, the lack of real choice women experience, as well as the silencing of women and providers with regard to feticide and LTOP. Underlying the three phases, and directly influencing the three prominent themes affecting women’s experiences, were the underlying and insidious structural inequality that undermined reproductive justice with regard to women’s decision-making, experiences of and recovery from feticide and LTOP. , Thesis (PhD) -- Faculty of Humanities, Psychology, 2023
- Full Text:
- Date Issued: 2023-10-13
Spatiotemporal ecology and potential displacement of white sharks in southern Africa
- Authors: Towner, Alison
- Date: 2023-10-13
- Subjects: Uncatalogued
- Language: English
- Type: Academic theses , Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/432275 , vital:72857
- Description: Restricted access. Expected release date in 2025. , Thesis (PhD) -- Faculty of Science, Ichthyology and Fisheries Science, 2023
- Full Text:
- Date Issued: 2023-10-13
- Authors: Towner, Alison
- Date: 2023-10-13
- Subjects: Uncatalogued
- Language: English
- Type: Academic theses , Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/432275 , vital:72857
- Description: Restricted access. Expected release date in 2025. , Thesis (PhD) -- Faculty of Science, Ichthyology and Fisheries Science, 2023
- Full Text:
- Date Issued: 2023-10-13
Species diversity and distribution patterns of three freshwater fish genera in southern Africa
- Authors: Mutizwa, Tadiwa Isaac
- Date: 2023-10-13
- Subjects: Uncatalogued
- Language: English
- Type: Academic theses , Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/431896 , vital:72813
- Description: Access restricted. Expected release in 2025. , Thesis (PhD) -- Faculty of Science, Ichthyology and Fisheries Science, 2023
- Full Text:
- Date Issued: 2023-10-13
- Authors: Mutizwa, Tadiwa Isaac
- Date: 2023-10-13
- Subjects: Uncatalogued
- Language: English
- Type: Academic theses , Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/431896 , vital:72813
- Description: Access restricted. Expected release in 2025. , Thesis (PhD) -- Faculty of Science, Ichthyology and Fisheries Science, 2023
- Full Text:
- Date Issued: 2023-10-13
Status and potential of green infrastructure to support urban resilience in Zomba City, Malawi
- Authors: Likongwe, Patrick Jeremy
- Date: 2023-10-13
- Subjects: Uncatalogued
- Language: English
- Type: Academic theses , Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/431821 , vital:72806 , DOI 10.21504/10962/431821
- Description: Small and medium towns with less than one million inhabitants are regarded to be the fastest growing urban centres globally, absorbing the bulk of the urban population growth. This urban growth drives the diminishing natural capital within the urban settings, resulting in compromised ecosystem services delivery, thereby rendering urban dwellers and systems less resilient to hazards and shocks. It is known that urban resilience discourse is rooted in robust, empirical assessments of the nature, composition and distribution of urban green infrastructure. Using the concept of green infrastructure, a mechanism for the delivery of ecosystem services that are multi-functional, well connected, and that integrate the grey-green infrastructure while providing room for social inclusion, anchored the research in a small city of Zomba, Malawi, which is a fast-growing city facing natural resource and ecosystem service degradation. The research therefore was set to understand the status of urban green infrastructure in Zomba over space and time as the basis for enhancing urban resilience. This was facilitated by an understanding of the spatial and temporal quantity, quality, diversity and distribution of urban greenspaces and the composition, structure, diversity and distributional differences of urban trees within different urban greenspace classes. Further to this was an investigation on the perceptions of and preferences for urban greenspaces among the different socio-demographic groups and finally the role of residents, institutions and institutional frameworks in building urban resilience through the delivery of ecosystem services. To achieve these objectives, the study used a suite of methods. First was geographical information system and remote sensing to understand the spatial and temporal changes in greenspaces within the city in terms of quantity and distribution. Ecological methods of assessing the tree species composition, diversity, population structure and distribution were also employed. To gauge the perceptions of and preferences for urban greenspaces, a survey was done, targeting users found within the urban greenspaces plus residents that claimed to have patronised the urban greenspaces. Finally, to understand the role of nature and the relevant urban ecosystem services provided towards building urban resilience, remote sensing and key informant interviews were done to enrich the literature searches on a case study of urban community efforts involved in managing Sadzi hill to reverse ecosystem disservices versus Chiperoni hill that was not managed. A general impression of declining urban green infrastructure was verified through the study. The city has indeed lost 14 % tree cover between 1998 and 2018 due to increased housing and creation of agricultural land to support the growing urban population. The city has 168 tree species with 65 % of them being indigenous. Residential areas were dominated by exotic trees, mainly due to the abundance of exotic fruit trees like Mangifera indica. Generally, the city has a good tree diversity score but unequally distributed, with the formal residential areas, where the colonial masters settled, having more trees than the mixed and informal residential areas. Nine urban greenspace types were identified, but there was a low per capita urban greenspace area of 11.6 m2 per person, slightly above the minimum standard set by World Health Organisation. From the preferences for and perceptions of urban greenspaces, patronage to these greenspaces (treated as parks) was highest among the educated youth, a majority being from the high housing density areas where there are no urban parks. Walking to the nearest urban greenspace took more than 10 minutes for 85 % of the respondents. With the available by-laws in support for the governance of greenspaces within the city and the role of residents towards the same, restoration efforts that targeted Sadzi hill yielded positive results through reversing ecosystem disservices that were being experienced by the community members around the hill. The community enjoys several ecosystem services that have also contributed towards building their resilience to climatic and environmental hazards. The results of this study have unveiled several green infrastructure attributes that can contribute towards building urban social ecological resilience like the presence of high proportion of indigenous tree species, healthy urban forest, high proportion of fruit trees, high diversity scores, unparalleled demand for urban greenspaces for cultural and regulatory ecosystem services, the willingness to pay and work towards managing and conserving greenspaces and the social capital available from the urban communities. However, the study also unveiled several green infrastructure related attributes that if not checked will continue to undermine efforts towards building urban resilience. These included the continued drop in tree and greenspace cover, poor governance of the available public greenspaces, unequal distribution of trees and urban greenspaces, poor management of greenspaces, bare river banks, lack of park amenities and a lack of a clear strategy, policy or an urban plan that clearly outlines green infrastructure. Efforts towards addressing these will mean acknowledging the role of green infrastructure in supporting urban social ecological resilience. , Thesis (PhD) -- Faculty of Science, Environmental Science, 2023
- Full Text:
- Date Issued: 2023-10-13
- Authors: Likongwe, Patrick Jeremy
- Date: 2023-10-13
- Subjects: Uncatalogued
- Language: English
- Type: Academic theses , Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/431821 , vital:72806 , DOI 10.21504/10962/431821
- Description: Small and medium towns with less than one million inhabitants are regarded to be the fastest growing urban centres globally, absorbing the bulk of the urban population growth. This urban growth drives the diminishing natural capital within the urban settings, resulting in compromised ecosystem services delivery, thereby rendering urban dwellers and systems less resilient to hazards and shocks. It is known that urban resilience discourse is rooted in robust, empirical assessments of the nature, composition and distribution of urban green infrastructure. Using the concept of green infrastructure, a mechanism for the delivery of ecosystem services that are multi-functional, well connected, and that integrate the grey-green infrastructure while providing room for social inclusion, anchored the research in a small city of Zomba, Malawi, which is a fast-growing city facing natural resource and ecosystem service degradation. The research therefore was set to understand the status of urban green infrastructure in Zomba over space and time as the basis for enhancing urban resilience. This was facilitated by an understanding of the spatial and temporal quantity, quality, diversity and distribution of urban greenspaces and the composition, structure, diversity and distributional differences of urban trees within different urban greenspace classes. Further to this was an investigation on the perceptions of and preferences for urban greenspaces among the different socio-demographic groups and finally the role of residents, institutions and institutional frameworks in building urban resilience through the delivery of ecosystem services. To achieve these objectives, the study used a suite of methods. First was geographical information system and remote sensing to understand the spatial and temporal changes in greenspaces within the city in terms of quantity and distribution. Ecological methods of assessing the tree species composition, diversity, population structure and distribution were also employed. To gauge the perceptions of and preferences for urban greenspaces, a survey was done, targeting users found within the urban greenspaces plus residents that claimed to have patronised the urban greenspaces. Finally, to understand the role of nature and the relevant urban ecosystem services provided towards building urban resilience, remote sensing and key informant interviews were done to enrich the literature searches on a case study of urban community efforts involved in managing Sadzi hill to reverse ecosystem disservices versus Chiperoni hill that was not managed. A general impression of declining urban green infrastructure was verified through the study. The city has indeed lost 14 % tree cover between 1998 and 2018 due to increased housing and creation of agricultural land to support the growing urban population. The city has 168 tree species with 65 % of them being indigenous. Residential areas were dominated by exotic trees, mainly due to the abundance of exotic fruit trees like Mangifera indica. Generally, the city has a good tree diversity score but unequally distributed, with the formal residential areas, where the colonial masters settled, having more trees than the mixed and informal residential areas. Nine urban greenspace types were identified, but there was a low per capita urban greenspace area of 11.6 m2 per person, slightly above the minimum standard set by World Health Organisation. From the preferences for and perceptions of urban greenspaces, patronage to these greenspaces (treated as parks) was highest among the educated youth, a majority being from the high housing density areas where there are no urban parks. Walking to the nearest urban greenspace took more than 10 minutes for 85 % of the respondents. With the available by-laws in support for the governance of greenspaces within the city and the role of residents towards the same, restoration efforts that targeted Sadzi hill yielded positive results through reversing ecosystem disservices that were being experienced by the community members around the hill. The community enjoys several ecosystem services that have also contributed towards building their resilience to climatic and environmental hazards. The results of this study have unveiled several green infrastructure attributes that can contribute towards building urban social ecological resilience like the presence of high proportion of indigenous tree species, healthy urban forest, high proportion of fruit trees, high diversity scores, unparalleled demand for urban greenspaces for cultural and regulatory ecosystem services, the willingness to pay and work towards managing and conserving greenspaces and the social capital available from the urban communities. However, the study also unveiled several green infrastructure related attributes that if not checked will continue to undermine efforts towards building urban resilience. These included the continued drop in tree and greenspace cover, poor governance of the available public greenspaces, unequal distribution of trees and urban greenspaces, poor management of greenspaces, bare river banks, lack of park amenities and a lack of a clear strategy, policy or an urban plan that clearly outlines green infrastructure. Efforts towards addressing these will mean acknowledging the role of green infrastructure in supporting urban social ecological resilience. , Thesis (PhD) -- Faculty of Science, Environmental Science, 2023
- Full Text:
- Date Issued: 2023-10-13
Synthesis of natural product-inspired imido and 3,5-disubstituted-1,2,4-oxadiazolo phosphonates as potential anti-malarial agents
- Authors: Chithambo, Bertha
- Date: 2023-10-13
- Subjects: Uncatalogued
- Language: English
- Type: Academic theses , Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/431637 , vital:72792
- Description: Access restricted. Expected release date in 2024. , Thesis (PhD) -- Faculty of Science, Chemistry, 2023
- Full Text:
- Date Issued: 2023-10-13
- Authors: Chithambo, Bertha
- Date: 2023-10-13
- Subjects: Uncatalogued
- Language: English
- Type: Academic theses , Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/431637 , vital:72792
- Description: Access restricted. Expected release date in 2024. , Thesis (PhD) -- Faculty of Science, Chemistry, 2023
- Full Text:
- Date Issued: 2023-10-13
The adoption of international financial reporting standards and foreign direct investment inflows: the moderating effect of the institutional environment in Africa
- Authors: Simbi, Chipo
- Date: 2023-10-13
- Subjects: International Financial Reporting Standards , Investments, Foreign , Institutional infrastructure , Accounting Law and legislation , Auditing Law and legislation , Generalized method of moments , Difference in differences
- Language: English
- Type: Academic theses , Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/419230 , vital:71627 , DOI 10.21504/10962/419230
- Description: Globalisation has created a need for an international accounting language to facilitate the smooth flow of trade across countries. In 2003, in an effort to establish a global financial reporting language, the International Accounting Standards Board (IASB) developed a single set of high-quality accounting principles known as the International Financial Reporting Standards (IFRS). Over the last decade, several African countries have adopted IFRS, and Africa has become the second-largest adopting continent after Europe. IFRS promotes improved quality of disclosure of accounting transactions, reduces information asymmetry between preparers and users of financial information, lowers the cost of investing, and breaks down information barriers to cross-border investment. Researchers suggest many benefits of IFRS adoption for macroeconomic indicators such as Foreign Direct Investment (FDI). The reduction in information acquisition and processing costs which translates into the reduction in investment costs, has been cited by most researchers. Researchers have argued, however, that the economic benefits of IFRS in Africa depend on the strength of the institutional environment. They also argue that the Western environment in which the IFRS was developed differs from the African environment. Thus, the universal approach of the IASB may not be appropriate due to the historical, social, economic and political context of African countries. The impact of the adoption of IFRS by African countries requires further examination, particularly as a weak institutional environment confronts many African countries. Three research questions are designed for this study; (1) Is there a significant change in FDI inflows for IFRS adopters in selected African countries after the adoption? (2) Is there a significant change in FDI inflows due to the institutional environment? (3) Does the institutional environment in IFRS-adopting countries moderate the effect of IFRS on FDI in selected African countries? The present study is underpinned by the new institutional theory, the information asymmetry theory, the eclectic theory and the signalling theory, each of which provide reasons why African countries have adopted IFRS. Nine hypotheses are developed, based on the research questions, and tested using the Systems General Method of Moments and the Difference-in-Difference method. The study uses data from 26 African countries, 15 adopting and 11 non-adopting countries, over the period 1996 - 2018. First, the study establishes that the adoption of IFRS positively and significantly affects FDI inflows into the selected sample of African countries. Second, the study concludes that legal enforcement, accounting and auditing standards enforcement, and language origin positively and significantly impact FDI inflows into these countries. Legal origin, however, has a positive but insignificant association with FDI inflows. Third, legal enforcement, historical ties, accounting and auditing enforcement and the quality of the institutional environment are found to moderate the effect of IFRS adoption on FDI inflows. These results indicate that IFRS is a crucial determinant of FDI inflows into African countries, but a supportive institutional environment is needed for African countries to attract FDI inflows after adoption. The results contribute to the accounting and finance literature on FDI into African countries, and may assist the investment community to assess the institutional risk associated with investing in IFRS adopting African countries. , Thesis (PhD) -- Faculty of Commerce, Accounting, 2023
- Full Text:
- Date Issued: 2023-10-13
- Authors: Simbi, Chipo
- Date: 2023-10-13
- Subjects: International Financial Reporting Standards , Investments, Foreign , Institutional infrastructure , Accounting Law and legislation , Auditing Law and legislation , Generalized method of moments , Difference in differences
- Language: English
- Type: Academic theses , Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/419230 , vital:71627 , DOI 10.21504/10962/419230
- Description: Globalisation has created a need for an international accounting language to facilitate the smooth flow of trade across countries. In 2003, in an effort to establish a global financial reporting language, the International Accounting Standards Board (IASB) developed a single set of high-quality accounting principles known as the International Financial Reporting Standards (IFRS). Over the last decade, several African countries have adopted IFRS, and Africa has become the second-largest adopting continent after Europe. IFRS promotes improved quality of disclosure of accounting transactions, reduces information asymmetry between preparers and users of financial information, lowers the cost of investing, and breaks down information barriers to cross-border investment. Researchers suggest many benefits of IFRS adoption for macroeconomic indicators such as Foreign Direct Investment (FDI). The reduction in information acquisition and processing costs which translates into the reduction in investment costs, has been cited by most researchers. Researchers have argued, however, that the economic benefits of IFRS in Africa depend on the strength of the institutional environment. They also argue that the Western environment in which the IFRS was developed differs from the African environment. Thus, the universal approach of the IASB may not be appropriate due to the historical, social, economic and political context of African countries. The impact of the adoption of IFRS by African countries requires further examination, particularly as a weak institutional environment confronts many African countries. Three research questions are designed for this study; (1) Is there a significant change in FDI inflows for IFRS adopters in selected African countries after the adoption? (2) Is there a significant change in FDI inflows due to the institutional environment? (3) Does the institutional environment in IFRS-adopting countries moderate the effect of IFRS on FDI in selected African countries? The present study is underpinned by the new institutional theory, the information asymmetry theory, the eclectic theory and the signalling theory, each of which provide reasons why African countries have adopted IFRS. Nine hypotheses are developed, based on the research questions, and tested using the Systems General Method of Moments and the Difference-in-Difference method. The study uses data from 26 African countries, 15 adopting and 11 non-adopting countries, over the period 1996 - 2018. First, the study establishes that the adoption of IFRS positively and significantly affects FDI inflows into the selected sample of African countries. Second, the study concludes that legal enforcement, accounting and auditing standards enforcement, and language origin positively and significantly impact FDI inflows into these countries. Legal origin, however, has a positive but insignificant association with FDI inflows. Third, legal enforcement, historical ties, accounting and auditing enforcement and the quality of the institutional environment are found to moderate the effect of IFRS adoption on FDI inflows. These results indicate that IFRS is a crucial determinant of FDI inflows into African countries, but a supportive institutional environment is needed for African countries to attract FDI inflows after adoption. The results contribute to the accounting and finance literature on FDI into African countries, and may assist the investment community to assess the institutional risk associated with investing in IFRS adopting African countries. , Thesis (PhD) -- Faculty of Commerce, Accounting, 2023
- Full Text:
- Date Issued: 2023-10-13
The androgenic and anabolic effects of pine pollen on Nile tilapia (Oreochromis niloticus)
- Authors: Abaho, Ivan
- Date: 2023-10-13
- Subjects: Uncatalogued
- Language: English
- Type: Academic theses , Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/431615 , vital:72790
- Description: Access restricted. Expected release date in 2025 , Thesis (PhD) -- Faculty of Science, Ichthyology and Fisheries Science, 2023
- Full Text:
- Date Issued: 2023-10-13
- Authors: Abaho, Ivan
- Date: 2023-10-13
- Subjects: Uncatalogued
- Language: English
- Type: Academic theses , Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/431615 , vital:72790
- Description: Access restricted. Expected release date in 2025 , Thesis (PhD) -- Faculty of Science, Ichthyology and Fisheries Science, 2023
- Full Text:
- Date Issued: 2023-10-13
The electrocatalytic activity of metallophthalocyanines and their conjugates with carbon nanomaterials and metal tungstate nanoparticles
- Authors: Ndebele, Nobuhle
- Date: 2023-10-13
- Subjects: Uncatalogued
- Language: English
- Type: Academic theses , Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/431934 , vital:72816 , DOI 10.21504/10962/431933
- Description: In this dissertation, seventeen phthalocyanine complexes were synthesised. Of these, only four are known and have been published. These complexes were synthesised using the conventional statistical condensation method that involves refluxing the phthalonitrile(s) (4-((1,3-bis(dimethylamino)propan-2-yl)oxy)phthalonitrile, 4-(4-carboxyphenoxy)phthalonitrile, 4-(4-acetylphenoxy)phthalonitrile, dimethyl 5-(3,4-dicyanophenoxy)-isophthalate, 4-(4-(tert-butyl)phenoxy)phthalonitrile, 5-phenoxylpicolinic acid phthalonitrile 4-(4-formylphenoxy) phthalonitrile, and 4-(4-(3-oxo-3-phenylprop-1-enyl) phenoxy) phthalonitrile) with the metal salt and 1,8-diazabicyclo[5.4.0]undecane as a catalyst in a high-temperature solvent. And thereafter (when necessary), isolation and purification of the target compounds were achieved through the use of silica column chromatography. These compounds were characterised using various analytical techniques such as; ultraviolet-visible absorption, mass spectroscopy, and Fourier transform infrared spectra and elemental analysis. These techniques proved that the complexes were successfully synthesised and isolated as pure compounds. Carbon-based (graphene quantum dots and nitrogen-doped graphene quantum dots) and metal oxide (bismuth tungsten oxide and nickel tungsten oxide) nanomaterials were synthesised. Together with the purchased single-walled carbon nanotubes, these nanomaterials were conjugated to some of the MPc complexes via non-covalent (carbon-based nanomaterials) and covalent (metal oxides) linkage forming hybrid materials. These nanomaterials and hybrids were characterised using various analytical methods (ultraviolet-visible absorption, X-ray diffraction, Raman spectroscopy, thermographic analysis, and dynamic light scattering). Nanomaterials were utilised herein to determine their effect on the properties of MPc complexes and provide a synergistic effect in the hope of enhancing these properties. All complexes synthesised in this work (MPcs, nanomaterials and hybrids) were employed as electrocatalysts in electrochemical sensing. These electrocatalysts were embedded onto the glassy carbon electrode via an adsorption method known as drop-casting. The modified electrode surfaces were characterised using cyclic voltammetry, electrochemical impedance spectroscopy and scanning electrochemical microscopy to determine various electrochemical parameters. These electrocatalysts were used in the detection of either nitrite, catechol and/or dopamine. The detection limits, sensitivities, kinetics and catalytic constants were among other parameters determined for each electrocatalyst. These electrocatalysts proved to be stable electrocatalysts that could potentially be used for practical applications. The determined parameters were comparable and sometimes better than those obtained in literature. , Thesis (PhD) -- Faculty of Science, Chemistry, 2023
- Full Text:
- Date Issued: 2023-10-13
- Authors: Ndebele, Nobuhle
- Date: 2023-10-13
- Subjects: Uncatalogued
- Language: English
- Type: Academic theses , Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/431934 , vital:72816 , DOI 10.21504/10962/431933
- Description: In this dissertation, seventeen phthalocyanine complexes were synthesised. Of these, only four are known and have been published. These complexes were synthesised using the conventional statistical condensation method that involves refluxing the phthalonitrile(s) (4-((1,3-bis(dimethylamino)propan-2-yl)oxy)phthalonitrile, 4-(4-carboxyphenoxy)phthalonitrile, 4-(4-acetylphenoxy)phthalonitrile, dimethyl 5-(3,4-dicyanophenoxy)-isophthalate, 4-(4-(tert-butyl)phenoxy)phthalonitrile, 5-phenoxylpicolinic acid phthalonitrile 4-(4-formylphenoxy) phthalonitrile, and 4-(4-(3-oxo-3-phenylprop-1-enyl) phenoxy) phthalonitrile) with the metal salt and 1,8-diazabicyclo[5.4.0]undecane as a catalyst in a high-temperature solvent. And thereafter (when necessary), isolation and purification of the target compounds were achieved through the use of silica column chromatography. These compounds were characterised using various analytical techniques such as; ultraviolet-visible absorption, mass spectroscopy, and Fourier transform infrared spectra and elemental analysis. These techniques proved that the complexes were successfully synthesised and isolated as pure compounds. Carbon-based (graphene quantum dots and nitrogen-doped graphene quantum dots) and metal oxide (bismuth tungsten oxide and nickel tungsten oxide) nanomaterials were synthesised. Together with the purchased single-walled carbon nanotubes, these nanomaterials were conjugated to some of the MPc complexes via non-covalent (carbon-based nanomaterials) and covalent (metal oxides) linkage forming hybrid materials. These nanomaterials and hybrids were characterised using various analytical methods (ultraviolet-visible absorption, X-ray diffraction, Raman spectroscopy, thermographic analysis, and dynamic light scattering). Nanomaterials were utilised herein to determine their effect on the properties of MPc complexes and provide a synergistic effect in the hope of enhancing these properties. All complexes synthesised in this work (MPcs, nanomaterials and hybrids) were employed as electrocatalysts in electrochemical sensing. These electrocatalysts were embedded onto the glassy carbon electrode via an adsorption method known as drop-casting. The modified electrode surfaces were characterised using cyclic voltammetry, electrochemical impedance spectroscopy and scanning electrochemical microscopy to determine various electrochemical parameters. These electrocatalysts were used in the detection of either nitrite, catechol and/or dopamine. The detection limits, sensitivities, kinetics and catalytic constants were among other parameters determined for each electrocatalyst. These electrocatalysts proved to be stable electrocatalysts that could potentially be used for practical applications. The determined parameters were comparable and sometimes better than those obtained in literature. , Thesis (PhD) -- Faculty of Science, Chemistry, 2023
- Full Text:
- Date Issued: 2023-10-13
The heterologous expression and in vitro biochemical characterization of the Hsp70 escort protein 1 and mitochondrial Hsp70 partner proteins of the Trypanosoma brucei parasite and humans
- Authors: Mahlalela, Maduma Ernst
- Date: 2023-10-13
- Subjects: Uncatalogued
- Language: English
- Type: Academic theses , Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/431832 , vital:72807 , DOI 10.21504/10962/431832
- Description: The 70 kDa family of heat shock proteins (Hsp70) plays a central role in the maintenance of cellular proteostasis, with paralogues occurring in all the major compartments of the eukaryotic cell. Hsp70s act in conjunction with proteins known as co-chaperones, as part of the larger molecular chaperone network. In the mitochondrion, Hsp70 (mtHsp70) is responsible for the import of proteins synthesized in the cytosol, protein folding in the matrix and the maintenance of the iron-sulphur cluster. In human cells mtHsp70 (HSPA9) is also referred to as mortalin, as the knockdown of the protein leads to cell mortality. Trypanosoma brucei is the causative agent of sleeping sickness in humans and nagana in animals. In the T. brucei parasite there are three identical mtHsp70 (TbmtHsp70) proteins that are produced, forming part of the Hsp70 machinery that is essential for parasite survival. In humans, the levels of HSPA9 are often elevated in non-communicable diseases such as cancer and neurodegeneration. Despite their vital cellular roles, mtHsp70s are characteristically prone to self-aggregation. The binding of the Hsp70 escort protein (Hep1) is required to prevent the aggregation of mtHsp70 proteins, enabling the proteins to function. In many non-communicable diseases, mtHsp70 and other molecular chaperones such as heat shock protein 90 (Hsp90) are being investigated as potential drug targets. Existing anti-trypanosomal drugs for treating sleeping sickness are toxic, having adverse side effects that are potentially lethal. Investigations into Hsp70s, and other molecular chaperones, form part of the research into the discovery of novel and efficacious therapeutics. This is the first study to characterise Hep1 and investigate its partnership with mtHsp70 in T. brucei. The overall aim of this study was to comparatively assess the T. brucei and human mtHsp70/Hep1 partnerships. The putative T. brucei Hep1 (TbHep1) orthologue was analysed in silico, and it was found to possess a zinc finger domain consisting of anti-parallel β-sheets that are characteristic of canonical Hep1 proteins, whilst the N-terminal domain was unstructured. Based on sequence analysis, the regions outside of the zinc finger domains lacked conservation. Despite the lack of sequence conservation, the N- and C-terminal regions of TbHep1 shared segments of similarity with Hep1 orthologues of other kinetoplastid and trypanosomal orthologues. The same held true for the N- and C-termini of human Hep1 (HsHep1) when compared to other Hep1 orthologues of mammalian origin. Biochemical analysis revealed TbmtHsp70 and HSPA9 to be prone to self-aggregation, which was reduced by co-expression with TbHep1 and HsHep1, respectively. Recently Hep1 proteins have been determined to be present in the cytosol. In this study, TbHep1 and HsHep1 also interacted with the cytosolic Hsp70s, HSPA1A and TbHsp70, by preventing their thermally induced aggregation and stimulating their ATPase activities. TbHep1 and HsHep1 also suppressed the thermally induced aggregation of the model substrates malate dehydrogenase and citrate synthase, independently of Hsp70. To date, only two Hep1 orthologues, HsHep1 and LbHep1, have been found to function in a similar manner to a J-protein co-chaperone by stimulating the ATPase activities of their partner mtHsp70 proteins. In this study, TbHep1 stimulated the ATPase activity of TbmtHsp70. HsHep1 also stimulated the ATPase activity of TbmtHsp70. However, the mechanism of action still needs to be determined. This study also explored the potential of the Hep1 orthologues to be functionally activated by oxidative stress, which is prevalent in mitochondria. The abilities of TbHep1 and HsHep1 to reduce the thermally induced aggregation of malate dehydrogenase were enhanced under oxidative conditions. Disrupting the function of Hep1 has been found to eventually lead to cell death, and given the critical role played by mtHsp70 in the cell, this partnership could be exploited as a potential drug target. In conclusion, this study demonstrated that TbHep1 and HsHep1 functionally interact with mtHsp70s, whilst also possessing independent chaperone activities that are also potentially influenced by the environmental redox state. , Thesis (PhD) -- Faculty of Science, Biotechnology Innovation Centre, 2023
- Full Text:
- Date Issued: 2023-10-13
- Authors: Mahlalela, Maduma Ernst
- Date: 2023-10-13
- Subjects: Uncatalogued
- Language: English
- Type: Academic theses , Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/431832 , vital:72807 , DOI 10.21504/10962/431832
- Description: The 70 kDa family of heat shock proteins (Hsp70) plays a central role in the maintenance of cellular proteostasis, with paralogues occurring in all the major compartments of the eukaryotic cell. Hsp70s act in conjunction with proteins known as co-chaperones, as part of the larger molecular chaperone network. In the mitochondrion, Hsp70 (mtHsp70) is responsible for the import of proteins synthesized in the cytosol, protein folding in the matrix and the maintenance of the iron-sulphur cluster. In human cells mtHsp70 (HSPA9) is also referred to as mortalin, as the knockdown of the protein leads to cell mortality. Trypanosoma brucei is the causative agent of sleeping sickness in humans and nagana in animals. In the T. brucei parasite there are three identical mtHsp70 (TbmtHsp70) proteins that are produced, forming part of the Hsp70 machinery that is essential for parasite survival. In humans, the levels of HSPA9 are often elevated in non-communicable diseases such as cancer and neurodegeneration. Despite their vital cellular roles, mtHsp70s are characteristically prone to self-aggregation. The binding of the Hsp70 escort protein (Hep1) is required to prevent the aggregation of mtHsp70 proteins, enabling the proteins to function. In many non-communicable diseases, mtHsp70 and other molecular chaperones such as heat shock protein 90 (Hsp90) are being investigated as potential drug targets. Existing anti-trypanosomal drugs for treating sleeping sickness are toxic, having adverse side effects that are potentially lethal. Investigations into Hsp70s, and other molecular chaperones, form part of the research into the discovery of novel and efficacious therapeutics. This is the first study to characterise Hep1 and investigate its partnership with mtHsp70 in T. brucei. The overall aim of this study was to comparatively assess the T. brucei and human mtHsp70/Hep1 partnerships. The putative T. brucei Hep1 (TbHep1) orthologue was analysed in silico, and it was found to possess a zinc finger domain consisting of anti-parallel β-sheets that are characteristic of canonical Hep1 proteins, whilst the N-terminal domain was unstructured. Based on sequence analysis, the regions outside of the zinc finger domains lacked conservation. Despite the lack of sequence conservation, the N- and C-terminal regions of TbHep1 shared segments of similarity with Hep1 orthologues of other kinetoplastid and trypanosomal orthologues. The same held true for the N- and C-termini of human Hep1 (HsHep1) when compared to other Hep1 orthologues of mammalian origin. Biochemical analysis revealed TbmtHsp70 and HSPA9 to be prone to self-aggregation, which was reduced by co-expression with TbHep1 and HsHep1, respectively. Recently Hep1 proteins have been determined to be present in the cytosol. In this study, TbHep1 and HsHep1 also interacted with the cytosolic Hsp70s, HSPA1A and TbHsp70, by preventing their thermally induced aggregation and stimulating their ATPase activities. TbHep1 and HsHep1 also suppressed the thermally induced aggregation of the model substrates malate dehydrogenase and citrate synthase, independently of Hsp70. To date, only two Hep1 orthologues, HsHep1 and LbHep1, have been found to function in a similar manner to a J-protein co-chaperone by stimulating the ATPase activities of their partner mtHsp70 proteins. In this study, TbHep1 stimulated the ATPase activity of TbmtHsp70. HsHep1 also stimulated the ATPase activity of TbmtHsp70. However, the mechanism of action still needs to be determined. This study also explored the potential of the Hep1 orthologues to be functionally activated by oxidative stress, which is prevalent in mitochondria. The abilities of TbHep1 and HsHep1 to reduce the thermally induced aggregation of malate dehydrogenase were enhanced under oxidative conditions. Disrupting the function of Hep1 has been found to eventually lead to cell death, and given the critical role played by mtHsp70 in the cell, this partnership could be exploited as a potential drug target. In conclusion, this study demonstrated that TbHep1 and HsHep1 functionally interact with mtHsp70s, whilst also possessing independent chaperone activities that are also potentially influenced by the environmental redox state. , Thesis (PhD) -- Faculty of Science, Biotechnology Innovation Centre, 2023
- Full Text:
- Date Issued: 2023-10-13
The professional experiences of early career counselling psychologists in South Africa: a mixed method study
- Authors: Haine, Phillipa Claire
- Date: 2023-10-13
- Subjects: Uncatalogued
- Language: English
- Type: Academic theses , Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/432321 , vital:72861 , DOI 10.21504/10962/432322
- Description: Counselling psychologists represent a considerable proportion of psychologists in South Africa (SA), yet knowledge on the discipline’s workforce is limited. In addition, professional lifespan issues have received inadequate attention, inclusive of the early career stage, identified as an exceptionally vulnerable segment of the professional lifespan. Undergirded by an interpretative phenomenology research paradigm, this mixed method sequential explanatory study, consisting of two distinct phases, aimed to explore the professional experiences of early career counselling psychologists (counselling ECPs) in SA, inclusive of employment trends, challenges and support needs. The quantitative phase (‘First Phase’) comprised of an online survey questionnaire (n = 512) to investigate the employment trends of counselling ECPs in SA. A qualitative phase (‘Second Phase’) followed, comprising of online semi-structured interviews with ten counselling ECPs. The rationale for this was that the preliminary quantitative data provided a broad understanding of the research problem, whereas the qualitative data sought to expand on the quantitative data by exploring the participants’ experiences in depth. Moreover, the collection of quantitative data provided a strong justification and phenomenological orientation for the second, qualitative, phase. The data from the two research phases were combined within a joint discussion to ensure a level of methodological complementarity and a more holistic understanding of the data captured. Trends from the first, quantitative, phase demonstrated that counselling ECPs differed across various domains from more senior generations. In the second, qualitative, phase, Interpretative Phenomenological Analysis of the data revealed three Group Experiential Themes: i) Complexity of finding and securing work, ii) Navigating an array of personal, professional and systemic challenges, and iii) Support as self-acquired. Overall, the findings suggest that counselling ECPs in SA face a variety of challenges upon entering the workforce, enhanced support is thus needed for this new, more diverse cohort of practitioners. Actionable recommendations are offered at various levels. , Thesis (PhD) -- Faculty of Humanities, Psychology, 2023
- Full Text:
- Date Issued: 2023-10-13
- Authors: Haine, Phillipa Claire
- Date: 2023-10-13
- Subjects: Uncatalogued
- Language: English
- Type: Academic theses , Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/432321 , vital:72861 , DOI 10.21504/10962/432322
- Description: Counselling psychologists represent a considerable proportion of psychologists in South Africa (SA), yet knowledge on the discipline’s workforce is limited. In addition, professional lifespan issues have received inadequate attention, inclusive of the early career stage, identified as an exceptionally vulnerable segment of the professional lifespan. Undergirded by an interpretative phenomenology research paradigm, this mixed method sequential explanatory study, consisting of two distinct phases, aimed to explore the professional experiences of early career counselling psychologists (counselling ECPs) in SA, inclusive of employment trends, challenges and support needs. The quantitative phase (‘First Phase’) comprised of an online survey questionnaire (n = 512) to investigate the employment trends of counselling ECPs in SA. A qualitative phase (‘Second Phase’) followed, comprising of online semi-structured interviews with ten counselling ECPs. The rationale for this was that the preliminary quantitative data provided a broad understanding of the research problem, whereas the qualitative data sought to expand on the quantitative data by exploring the participants’ experiences in depth. Moreover, the collection of quantitative data provided a strong justification and phenomenological orientation for the second, qualitative, phase. The data from the two research phases were combined within a joint discussion to ensure a level of methodological complementarity and a more holistic understanding of the data captured. Trends from the first, quantitative, phase demonstrated that counselling ECPs differed across various domains from more senior generations. In the second, qualitative, phase, Interpretative Phenomenological Analysis of the data revealed three Group Experiential Themes: i) Complexity of finding and securing work, ii) Navigating an array of personal, professional and systemic challenges, and iii) Support as self-acquired. Overall, the findings suggest that counselling ECPs in SA face a variety of challenges upon entering the workforce, enhanced support is thus needed for this new, more diverse cohort of practitioners. Actionable recommendations are offered at various levels. , Thesis (PhD) -- Faculty of Humanities, Psychology, 2023
- Full Text:
- Date Issued: 2023-10-13
The relevance of career counselling in higher education: a study following students at a South African university
- Authors: Lewis, Christine
- Date: 2023-10-13
- Subjects: Uncatalogued
- Language: English
- Type: Academic theses , Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/432347 , vital:72863 , DOI 10.21504/10962/432348
- Description: Very few students in South Africa (SA) receive adequate career counselling at school and often arrive at institutions of higher learning without a clear sense of what their prospective careers will entail. The limited access to career counselling and assessment is further compounded by criticisms of popular career assessment instruments used in SA, where the primary goal of career counselling and assessment is to match clients to careers for job placement. This approach no longer serves the needs of a diverse SA population and disregards contextual influences on careers. Therefore, a need exists to understand and inform career counselling interventions and to guard against the provision of de-contextualised and contextually insensitive approaches. Moreover, changes in the workplace, where career change has become the norm as the world of work has moved away from stability and permanency to fluidity, calls for a contemporary response from career counselling theories, practitioners as well as researchers, to equip clients with the necessary skills to respond to these changes. Thus, SA institutions of higher learning need to innovate their practices to more inclusively, effectively, and justly serve the needs of a diverse student population for work success in a developing nation and a complex world. This study aimed to evaluate the relevance and effectiveness of a university’s career counselling services from the students’ perspectives. It focuses on gaining an indication of the perceived effectiveness of assessment measures used, and to ascertain the influences that impact on individual students’ career decision-making over the course of undergraduate studies. Due to the increasing recognition for the need to develop a contextualised approach to career development interventions, this study included the SACII, a locally developed interest inventory as part of a career assessment battery, with a group of university students. A pragmatic approach using mixed-methods was used. Multiple case studies of the career trajectories of a cohort of undergraduate students who had undertaken career assessments at the university career centre, were tracked longitudinally over the course of undergraduate studies. Data were generated through vignettes that included the 13 participants' career assessment reports, a service evaluation questionnaire and two successive follow-up interviews. Each participant's first follow-up interview occurred six months after their career assessment feedback session; and the second follow-up was in the final year of undergraduate studies, after eighteen months. Descriptive statistical analysis summarised the basic features of the quantitative data from the evaluation questionnaire. Thematic analysis was used for organisation and analysis of the follow-up interview data. Findings were that the career counselling and assessment facilitated greater self-knowledge in relation to career decision-making, assisted with selecting degree major subjects and enhanced career planning abilities. Using locally developed assessment measures in career counselling proved to be useful. Exploring career development from an overarching developmental contextual framework that is applicable and well-suited to the SA context provided a deeper understanding of contextual influences that impact on students' career decision-making processes. , Thesis (PhD) -- Faculty of Humanities, Psychology, 2023
- Full Text:
- Date Issued: 2023-10-13
- Authors: Lewis, Christine
- Date: 2023-10-13
- Subjects: Uncatalogued
- Language: English
- Type: Academic theses , Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/432347 , vital:72863 , DOI 10.21504/10962/432348
- Description: Very few students in South Africa (SA) receive adequate career counselling at school and often arrive at institutions of higher learning without a clear sense of what their prospective careers will entail. The limited access to career counselling and assessment is further compounded by criticisms of popular career assessment instruments used in SA, where the primary goal of career counselling and assessment is to match clients to careers for job placement. This approach no longer serves the needs of a diverse SA population and disregards contextual influences on careers. Therefore, a need exists to understand and inform career counselling interventions and to guard against the provision of de-contextualised and contextually insensitive approaches. Moreover, changes in the workplace, where career change has become the norm as the world of work has moved away from stability and permanency to fluidity, calls for a contemporary response from career counselling theories, practitioners as well as researchers, to equip clients with the necessary skills to respond to these changes. Thus, SA institutions of higher learning need to innovate their practices to more inclusively, effectively, and justly serve the needs of a diverse student population for work success in a developing nation and a complex world. This study aimed to evaluate the relevance and effectiveness of a university’s career counselling services from the students’ perspectives. It focuses on gaining an indication of the perceived effectiveness of assessment measures used, and to ascertain the influences that impact on individual students’ career decision-making over the course of undergraduate studies. Due to the increasing recognition for the need to develop a contextualised approach to career development interventions, this study included the SACII, a locally developed interest inventory as part of a career assessment battery, with a group of university students. A pragmatic approach using mixed-methods was used. Multiple case studies of the career trajectories of a cohort of undergraduate students who had undertaken career assessments at the university career centre, were tracked longitudinally over the course of undergraduate studies. Data were generated through vignettes that included the 13 participants' career assessment reports, a service evaluation questionnaire and two successive follow-up interviews. Each participant's first follow-up interview occurred six months after their career assessment feedback session; and the second follow-up was in the final year of undergraduate studies, after eighteen months. Descriptive statistical analysis summarised the basic features of the quantitative data from the evaluation questionnaire. Thematic analysis was used for organisation and analysis of the follow-up interview data. Findings were that the career counselling and assessment facilitated greater self-knowledge in relation to career decision-making, assisted with selecting degree major subjects and enhanced career planning abilities. Using locally developed assessment measures in career counselling proved to be useful. Exploring career development from an overarching developmental contextual framework that is applicable and well-suited to the SA context provided a deeper understanding of contextual influences that impact on students' career decision-making processes. , Thesis (PhD) -- Faculty of Humanities, Psychology, 2023
- Full Text:
- Date Issued: 2023-10-13
The use of dynamic software to potentially enhance conceptual understanding and a productive disposition in the visual learning of algebra: an interventionist case study
- Authors: Junius, Daniel Franscius
- Date: 2023-10-13
- Subjects: Uncatalogued
- Language: English
- Type: Academic theses , Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/431542 , vital:72784 , DOI 10.21504/10962/431542
- Description: Over the decades, the didactics and practice of teaching mathematics has offered many unique challenges and opportunities for exploration and understanding. The introduction and development of technology into mathematics is one of the occurrences which has also contributed to a new discourse in teaching mathematics – in this case the teaching of algebra. Algebra is still seen as a gatekeeper and remains as one of the key reasons for a negative disposition amongst learners towards learning the subject. Across the globe psychologists, philosophers and educators continue to engage in debates and research projects in search of answers and solutions for the improvement of algebra teaching and an improvement in dispositions towards learning algebra. This thesis reports on a research project that focused on the use of dynamic software to enhance the conceptual understanding and productive dispositions of selected learners through the visual learning of abstract algebraic concepts. The research was executed as an interventionist case study. A case study methodological strategy was adopted with two groups of 30 Grade 9 learners. One group was a Grade 9 mathematics class of a school in Windhoek who scored above average in algebra but showed a very low disposition score, while the other group was made up of learners from a community project who scored high on the disposition scale but achieved below average results in algebra. The analytical framework of the case study is structured around a combination of complementary algebraic topics presented through visual learning, with GeoGebra as a medium of instruction. With the focus on visualisation and the use of technology the study investigated and attempted to understand how participants processed and internalised algebraic concepts to make sense of abstract algebraic concepts and eventually gain sustained conceptual understanding. The study was framed by the theoretical theories of constructivism and the Dual Coding Theory. For the collection of data, a mixed methods approach was adopted following three cycles. Three algebraic topics were taught with GeoGebra applets yielding both qualitative and quantitative data, through the observation of participants, screen captures and reflective interviews, using instruments designed specifically for the study and collecting quantitative achievement test results. The study, a journey that both the participants and the researcher embarked upon, revealed that the use of technology enhanced conceptual understanding for both groups and both groups showed a positive change in disposition towards learning algebra. The intervention with GeoGebra consistently and progressively improved in terms of conceptual understanding and dispositions towards learning algebra significant improvements in results were achieved. The findings showed that this approach to teaching algebra yielded positive results and gave new insights into visual teaching with technology. New opportunities for further research were created. , Thesis (PhD) -- Faculty of Education, Secondary and Post-School Education, 2023
- Full Text:
- Date Issued: 2023-10-13
- Authors: Junius, Daniel Franscius
- Date: 2023-10-13
- Subjects: Uncatalogued
- Language: English
- Type: Academic theses , Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/431542 , vital:72784 , DOI 10.21504/10962/431542
- Description: Over the decades, the didactics and practice of teaching mathematics has offered many unique challenges and opportunities for exploration and understanding. The introduction and development of technology into mathematics is one of the occurrences which has also contributed to a new discourse in teaching mathematics – in this case the teaching of algebra. Algebra is still seen as a gatekeeper and remains as one of the key reasons for a negative disposition amongst learners towards learning the subject. Across the globe psychologists, philosophers and educators continue to engage in debates and research projects in search of answers and solutions for the improvement of algebra teaching and an improvement in dispositions towards learning algebra. This thesis reports on a research project that focused on the use of dynamic software to enhance the conceptual understanding and productive dispositions of selected learners through the visual learning of abstract algebraic concepts. The research was executed as an interventionist case study. A case study methodological strategy was adopted with two groups of 30 Grade 9 learners. One group was a Grade 9 mathematics class of a school in Windhoek who scored above average in algebra but showed a very low disposition score, while the other group was made up of learners from a community project who scored high on the disposition scale but achieved below average results in algebra. The analytical framework of the case study is structured around a combination of complementary algebraic topics presented through visual learning, with GeoGebra as a medium of instruction. With the focus on visualisation and the use of technology the study investigated and attempted to understand how participants processed and internalised algebraic concepts to make sense of abstract algebraic concepts and eventually gain sustained conceptual understanding. The study was framed by the theoretical theories of constructivism and the Dual Coding Theory. For the collection of data, a mixed methods approach was adopted following three cycles. Three algebraic topics were taught with GeoGebra applets yielding both qualitative and quantitative data, through the observation of participants, screen captures and reflective interviews, using instruments designed specifically for the study and collecting quantitative achievement test results. The study, a journey that both the participants and the researcher embarked upon, revealed that the use of technology enhanced conceptual understanding for both groups and both groups showed a positive change in disposition towards learning algebra. The intervention with GeoGebra consistently and progressively improved in terms of conceptual understanding and dispositions towards learning algebra significant improvements in results were achieved. The findings showed that this approach to teaching algebra yielded positive results and gave new insights into visual teaching with technology. New opportunities for further research were created. , Thesis (PhD) -- Faculty of Education, Secondary and Post-School Education, 2023
- Full Text:
- Date Issued: 2023-10-13