The cultural significance of plant-fiber crafts in Southern Africa: a comparative study of Eswatini, Malawi, and Zimbabwe
- Pullanikkatil, Deepa, Thondhlana, Gladman, Shackleton, Charlie M
- Authors: Pullanikkatil, Deepa , Thondhlana, Gladman , Shackleton, Charlie M
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/399860 , vital:69564 , xlink:href="https://doi.org/10.1080/14728028.2021.1998797"
- Description: Traditional handicrafts made from various plant materials are produced by most cultures around the world. Many originated through symbolic and utilitarian needs that became ritualized through time, thereby gradually attaining greater value as cultural items or symbols rather than solely functional ones. Here we report on a survey of 343 crafters across Eswatini, Malawi, and Zimbabwe in southern Africa regarding the cultural uses and significance of the items they make from wild plant fibers and sell to local communities or tourists. The plant materials used were largely dictated by tradition and local availability and were crafted into a diverse range of products including baskets, mats, brooms, storage containers, hats, fish traps, ornaments, and furniture. Many products had uses and cultural significance at major ceremonies or rituals, such as weddings, funerals, initiation, and divination. The preparation and design of the different crafts were influenced by tradition as well as market demand as indicated by tourist fashions and advice provided by government or non-government agencies to boost income generation from crafts. Although the crafting of cultural objects is increasingly commercialized and subject to the tastes and fashions of tourist markets in the region, the traditional and cultural significance of such artifacts remains widely recognized and valued.
- Full Text:
- Date Issued: 2021
- Authors: Pullanikkatil, Deepa , Thondhlana, Gladman , Shackleton, Charlie M
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/399860 , vital:69564 , xlink:href="https://doi.org/10.1080/14728028.2021.1998797"
- Description: Traditional handicrafts made from various plant materials are produced by most cultures around the world. Many originated through symbolic and utilitarian needs that became ritualized through time, thereby gradually attaining greater value as cultural items or symbols rather than solely functional ones. Here we report on a survey of 343 crafters across Eswatini, Malawi, and Zimbabwe in southern Africa regarding the cultural uses and significance of the items they make from wild plant fibers and sell to local communities or tourists. The plant materials used were largely dictated by tradition and local availability and were crafted into a diverse range of products including baskets, mats, brooms, storage containers, hats, fish traps, ornaments, and furniture. Many products had uses and cultural significance at major ceremonies or rituals, such as weddings, funerals, initiation, and divination. The preparation and design of the different crafts were influenced by tradition as well as market demand as indicated by tourist fashions and advice provided by government or non-government agencies to boost income generation from crafts. Although the crafting of cultural objects is increasingly commercialized and subject to the tastes and fashions of tourist markets in the region, the traditional and cultural significance of such artifacts remains widely recognized and valued.
- Full Text:
- Date Issued: 2021
The distribution of selected woody invasive alien species in small towns in the Eastern Cape, South Africa
- Mabusela, A, Shackleton, Charlie M, Gewdla, Nanamhla
- Authors: Mabusela, A , Shackleton, Charlie M , Gewdla, Nanamhla
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/401289 , vital:69723 , xlink:href="https://doi.org/10.1016/j.sajb.2021.05.019"
- Description: The potential and real negative and positive effects of invasive alien species (IAS) are increasingly recognised by researchers, land managers and decision-makers. However, most of the research and knowledge stems from understandings developed from rural and natural landscapes, with relatively little derived from studies in urban settings. Small towns in particular pose a novel suite of conditions that make the study and mangment of IAS particularly pressing. Here we examined the distribution of seven woody IAS (Acacia mearnsii, Cestrum laevigatum, Eucalyptus spp., Lantana camara, Melia azedarach, Senna didymobotrya and Solanaum mauritianum) within and between five small towns in the Eastern Cape via means of drive-by road surveys of every street in each town. Across the five towns and seven IAS 4,307 individuals were recorded, with the highest densities found in the two more coastal towns. Almost two-thirds (63%) of the IAS were located in residential properties, 24 % in public spaces and 13 % on road verges, closely mirroring the proportional area of these landuses. Within the residential landuse zone specifically, the townships had between 41 % and 61 % of all the recorded IAS plants per town, followed by the affluent neighbourhoods (22 – 41 %) and lastly, the RDP neighbourhoods (6 – 32 %). Cestrum laevigatum was the most abundant woody IAS across the five towns as a whole (1,783 inviduals). The second-most abundant species was M. azedarach (914 stems) and the least recorded was S. mauritianum (44). Additionally, there were differences in the general distribution of the seven species across residential neighbourhoods, with C. laevigatum (71.2 %), M. azedarach (49.3 %) and S. mauritianum (60.0 %) concentrated in township neighbourhoods, whilst A. mearnsii (66.4 %), L. camara (64.1 %) and Eucalyptus spp. (48.6 %) were most common in the affluent neighbourhoods. This study confirms that woody IAS are widespread in small towns of the region, but that they are unevenly distributed between towns and landuses within towns, indicating the need for local-scale inventories and management.
- Full Text:
- Date Issued: 2021
- Authors: Mabusela, A , Shackleton, Charlie M , Gewdla, Nanamhla
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/401289 , vital:69723 , xlink:href="https://doi.org/10.1016/j.sajb.2021.05.019"
- Description: The potential and real negative and positive effects of invasive alien species (IAS) are increasingly recognised by researchers, land managers and decision-makers. However, most of the research and knowledge stems from understandings developed from rural and natural landscapes, with relatively little derived from studies in urban settings. Small towns in particular pose a novel suite of conditions that make the study and mangment of IAS particularly pressing. Here we examined the distribution of seven woody IAS (Acacia mearnsii, Cestrum laevigatum, Eucalyptus spp., Lantana camara, Melia azedarach, Senna didymobotrya and Solanaum mauritianum) within and between five small towns in the Eastern Cape via means of drive-by road surveys of every street in each town. Across the five towns and seven IAS 4,307 individuals were recorded, with the highest densities found in the two more coastal towns. Almost two-thirds (63%) of the IAS were located in residential properties, 24 % in public spaces and 13 % on road verges, closely mirroring the proportional area of these landuses. Within the residential landuse zone specifically, the townships had between 41 % and 61 % of all the recorded IAS plants per town, followed by the affluent neighbourhoods (22 – 41 %) and lastly, the RDP neighbourhoods (6 – 32 %). Cestrum laevigatum was the most abundant woody IAS across the five towns as a whole (1,783 inviduals). The second-most abundant species was M. azedarach (914 stems) and the least recorded was S. mauritianum (44). Additionally, there were differences in the general distribution of the seven species across residential neighbourhoods, with C. laevigatum (71.2 %), M. azedarach (49.3 %) and S. mauritianum (60.0 %) concentrated in township neighbourhoods, whilst A. mearnsii (66.4 %), L. camara (64.1 %) and Eucalyptus spp. (48.6 %) were most common in the affluent neighbourhoods. This study confirms that woody IAS are widespread in small towns of the region, but that they are unevenly distributed between towns and landuses within towns, indicating the need for local-scale inventories and management.
- Full Text:
- Date Issued: 2021
The effect of habitat and spatial management on reef fish in an established marine protected area
- Authors: Dames, Vivienne Abigail
- Date: 2021
- Subjects: iSimangaliso Wetland Park (South Africa) -- Management , Reef fishes -- South Africa -- KwaZulu-Natal , Baited remote underwater stereo-video systems (stereo-BRUVs) , Marine parks and reserves -- Monitoring -- South Africa -- KwaZulu-Natal , Fish populations -- Measurement
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/171150 , vital:42024
- Description: The persistence of harvested fish populations in the Anthropocene will be determined, above all, by how they respond to the interacting effects of climate change and fisheries exploitation. Predicting how populations will respond to both these threats is essential for any adaptive and sustainable management strategy. The response of fish populations to climate change is underpinned by physiological rates and tolerances, and emerging evidence suggests there may be physiological-based selection in capture fisheries. By quantifying important physiological rates of a model species, the endemic seabream, Chrysoblephus laticeps, across ecologically relevant thermal gradients and from populations subjected to varying intensities of commercial exploitation, this thesis aimed to 1) provide the first physiologically grounded climate resilience assessment for a South African linefish species, and 2) elucidate whether exploitation can drive populations to less physiologically resilient states in response to climate change. To identify physiologically limiting sea temperatures and to determine if exploitation alters physiological trait distributions, an intermittent flow respirometry experiment was used to test the metabolic response of spatially protected and exploited populations of C. laticeps to acute thermal variability. Exploited populations showed reduced metabolic phenotype diversity, fewer high-performance aerobic scope phenotypes, and a significantly lower aerobic scope curve across all test temperatures. Although both populations maintained a relatively high aerobic scope across a wide thermal range, their metabolic rates were compromised when extreme cold events were simulated (8 °C), suggesting that predicted future increases in upwelling frequency and intensity may be the primary limiting factor in a more thermally variable future ocean. The increment widths of annuli in the otoliths of C. laticeps from contemporary and historic collections were measured, as a proxy for the annual growth rate of exploited and protected populations. Hierarchical mixed models were used to partition growth variation within and among individuals and ascribe growth to intrinsic and extrinsic effects. The best model for the protected population indicated that the growth response of C. laticeps was poorer during years characterised by a high cumulative upwelling intensity, and better during years characterised by higher mean autumn sea surface temperatures. The exploited population growth chronology was too short to identify an extrinsic growth driver. The growth results again highlight the role of thermal variability in modulating the response of C. laticeps to its ambient environment and indicate that the predicted increases in upwelling frequency and intensity may constrain future growth rates of this species. A metabolic index (ϕ), representing the ratio of O2 supply to demand at various temperatures and oxygen concentrations, was estimated for exploited and protected populations of C. laticeps and used to predict future distribution responses. There was no difference in the laboratory calibrations of ϕ between populations, and all data was subsequently combined into a single piecewise (12 °C) calibrated ϕ model. To predict the distribution of C. laticeps, ϕ was projected across a high-resolution ocean model of the South African coastal zone, and a species distribution model implemented using the random forest algorithm and C. laticeps occurrence points. The future distribution of C. laticeps was estimated by predicting trained models across ocean model projections up to 2100. The best predictor of C. laticeps’ current distribution was minimum monthly ϕ and future predictions indicated only a slight range contraction on either edge of C. laticeps’ distribution by 2100. In order to provide policy makers, currently developing climate change management frameworks for South Africa’s ocean, with a usable output, the results of all research chapters were combined into a marine spatial model. The spatial model identified areas where C. laticeps is predicted to be resilient to climate change in terms of physiology, growth and distribution responses, which can then be prioritised for adaptation measures, such as spatial protection from exploitation. While these results are specific to C. laticeps, the methodology developed to identify areas of climate resilience has broad applications across taxa. From a global perspective, perhaps the most salient points to consider from this case study are the evidence of selective exploitation on physiological traits and the importance of environmental variability, rather than long-term mean climate changes, in affecting organism performance. These ideas are congruent with the current paradigm shift in how we think of the ocean, selective fisheries, and how they relate to organism climate resilience.
- Full Text:
- Date Issued: 2021
- Authors: Dames, Vivienne Abigail
- Date: 2021
- Subjects: iSimangaliso Wetland Park (South Africa) -- Management , Reef fishes -- South Africa -- KwaZulu-Natal , Baited remote underwater stereo-video systems (stereo-BRUVs) , Marine parks and reserves -- Monitoring -- South Africa -- KwaZulu-Natal , Fish populations -- Measurement
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/171150 , vital:42024
- Description: The persistence of harvested fish populations in the Anthropocene will be determined, above all, by how they respond to the interacting effects of climate change and fisheries exploitation. Predicting how populations will respond to both these threats is essential for any adaptive and sustainable management strategy. The response of fish populations to climate change is underpinned by physiological rates and tolerances, and emerging evidence suggests there may be physiological-based selection in capture fisheries. By quantifying important physiological rates of a model species, the endemic seabream, Chrysoblephus laticeps, across ecologically relevant thermal gradients and from populations subjected to varying intensities of commercial exploitation, this thesis aimed to 1) provide the first physiologically grounded climate resilience assessment for a South African linefish species, and 2) elucidate whether exploitation can drive populations to less physiologically resilient states in response to climate change. To identify physiologically limiting sea temperatures and to determine if exploitation alters physiological trait distributions, an intermittent flow respirometry experiment was used to test the metabolic response of spatially protected and exploited populations of C. laticeps to acute thermal variability. Exploited populations showed reduced metabolic phenotype diversity, fewer high-performance aerobic scope phenotypes, and a significantly lower aerobic scope curve across all test temperatures. Although both populations maintained a relatively high aerobic scope across a wide thermal range, their metabolic rates were compromised when extreme cold events were simulated (8 °C), suggesting that predicted future increases in upwelling frequency and intensity may be the primary limiting factor in a more thermally variable future ocean. The increment widths of annuli in the otoliths of C. laticeps from contemporary and historic collections were measured, as a proxy for the annual growth rate of exploited and protected populations. Hierarchical mixed models were used to partition growth variation within and among individuals and ascribe growth to intrinsic and extrinsic effects. The best model for the protected population indicated that the growth response of C. laticeps was poorer during years characterised by a high cumulative upwelling intensity, and better during years characterised by higher mean autumn sea surface temperatures. The exploited population growth chronology was too short to identify an extrinsic growth driver. The growth results again highlight the role of thermal variability in modulating the response of C. laticeps to its ambient environment and indicate that the predicted increases in upwelling frequency and intensity may constrain future growth rates of this species. A metabolic index (ϕ), representing the ratio of O2 supply to demand at various temperatures and oxygen concentrations, was estimated for exploited and protected populations of C. laticeps and used to predict future distribution responses. There was no difference in the laboratory calibrations of ϕ between populations, and all data was subsequently combined into a single piecewise (12 °C) calibrated ϕ model. To predict the distribution of C. laticeps, ϕ was projected across a high-resolution ocean model of the South African coastal zone, and a species distribution model implemented using the random forest algorithm and C. laticeps occurrence points. The future distribution of C. laticeps was estimated by predicting trained models across ocean model projections up to 2100. The best predictor of C. laticeps’ current distribution was minimum monthly ϕ and future predictions indicated only a slight range contraction on either edge of C. laticeps’ distribution by 2100. In order to provide policy makers, currently developing climate change management frameworks for South Africa’s ocean, with a usable output, the results of all research chapters were combined into a marine spatial model. The spatial model identified areas where C. laticeps is predicted to be resilient to climate change in terms of physiology, growth and distribution responses, which can then be prioritised for adaptation measures, such as spatial protection from exploitation. While these results are specific to C. laticeps, the methodology developed to identify areas of climate resilience has broad applications across taxa. From a global perspective, perhaps the most salient points to consider from this case study are the evidence of selective exploitation on physiological traits and the importance of environmental variability, rather than long-term mean climate changes, in affecting organism performance. These ideas are congruent with the current paradigm shift in how we think of the ocean, selective fisheries, and how they relate to organism climate resilience.
- Full Text:
- Date Issued: 2021
The effects of elevated atmospheric CO2 concentration on the biological control of invasive aquatic weeds
- Baso, Nompumelelo C, Coetzee, Julie A, Ripley, Brad S, Hill, Martin P
- Authors: Baso, Nompumelelo C , Coetzee, Julie A , Ripley, Brad S , Hill, Martin P
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/419423 , vital:71643 , xlink:href="https://doi.org/10.1016/j.aquabot.2020.103348"
- Description: There has been a rapid increase in atmospheric CO2 concentration, from pre-industrial values of 280 ppm to more than 400 ppm currently, and this is expected to double by the end of the 21st century. Studies have shown that plants grown at elevated CO2 concentrations have increased growth rates and invest more in carbon-based defences. This has important implications for the management of invasive alien plants, especially using biological control which is mostly dependent on herbivorous insects. The aim of this study was to investigate the effects of elevated atmospheric CO2 on the biological control of four invasive aquatic weeds (Azolla filiculoides, Salvinia molesta, Pistia stratiotes and Myriophyllum aquaticum). These species are currently under successful control by their respective biological control agents (Stenopelmus rufinasus, Cyrtobagous salviniae, Neohydronomus affinis, and Lysathia sp.) in South Africa. The plant species were grown in a two factorial design experiment, where atmospheric CO2 concentrations were set at ambient (400 ppm) or elevated (800 ppm), and plants were either subjected to or not subjected to herbivory by their target biological control agents. There was an overall increase in biomass production and C:N across all species at elevated CO2, both in the absence and presence of biological control, although C:N of M. aquaticum and biomass of A. filiculoides with herbivory were not constant with this trend. Insect feeding damage was reduced by elevated CO2, except for S. molesta. Thus, we can expect that plants will respond differently to CO2 increase, but the general trend suggests that these species will become more challenging to manage through biological control in future.
- Full Text:
- Date Issued: 2021
- Authors: Baso, Nompumelelo C , Coetzee, Julie A , Ripley, Brad S , Hill, Martin P
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/419423 , vital:71643 , xlink:href="https://doi.org/10.1016/j.aquabot.2020.103348"
- Description: There has been a rapid increase in atmospheric CO2 concentration, from pre-industrial values of 280 ppm to more than 400 ppm currently, and this is expected to double by the end of the 21st century. Studies have shown that plants grown at elevated CO2 concentrations have increased growth rates and invest more in carbon-based defences. This has important implications for the management of invasive alien plants, especially using biological control which is mostly dependent on herbivorous insects. The aim of this study was to investigate the effects of elevated atmospheric CO2 on the biological control of four invasive aquatic weeds (Azolla filiculoides, Salvinia molesta, Pistia stratiotes and Myriophyllum aquaticum). These species are currently under successful control by their respective biological control agents (Stenopelmus rufinasus, Cyrtobagous salviniae, Neohydronomus affinis, and Lysathia sp.) in South Africa. The plant species were grown in a two factorial design experiment, where atmospheric CO2 concentrations were set at ambient (400 ppm) or elevated (800 ppm), and plants were either subjected to or not subjected to herbivory by their target biological control agents. There was an overall increase in biomass production and C:N across all species at elevated CO2, both in the absence and presence of biological control, although C:N of M. aquaticum and biomass of A. filiculoides with herbivory were not constant with this trend. Insect feeding damage was reduced by elevated CO2, except for S. molesta. Thus, we can expect that plants will respond differently to CO2 increase, but the general trend suggests that these species will become more challenging to manage through biological control in future.
- Full Text:
- Date Issued: 2021
The effects of supply chain cooperation on humanitarian relief operations: A case of Cyclone Idai in Zimbabwe
- Chari, Felix, Muzinda, Ozwell, Novukela, Cawe, Ngcamu, Bethuel S.
- Authors: Chari, Felix , Muzinda, Ozwell , Novukela, Cawe , Ngcamu, Bethuel S.
- Date: 2021
- Subjects: Cyclone damage Business logistics Article
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/11260/7155 , vital:53076 , xlink:href="https://doi.org/10.4102/jtscm.v15i0.532"
- Description: Background: The increased frequency of occurrence and complexity of disasters, the world over, have called for increased cooperation amongst stakeholders to deliver humanitarian aid. Objectives: This study came as a result of the growing interest focussed on creating and implementing cooperation to facilitate management of supply chain-related activities in the humanitarian sector. This study therefore sought to gain a better understanding of the effectiveness of supply chain cooperation in aid delivery performance variables, specifically in the context of Cyclone Idai humanitarian relief operations in Zimbabwe. Method: A pragmatic research paradigm was adopted, where the researchers took a mixed approach informed by both quantitative and qualitative research tools. Results: Findings of this study show a significant and positive impact of humanitarian supply chain (HSC) cooperation in achieving output, resource and flexibility performance in the delivery of aid. These findings will change the shape of humanitarian response to have more cooperation amongst organisations rather than responding as single entities. Conclusion: This study will therefore contribute to how humanitarian organisations improve their approach to future disasters through cooperation in their supply chain activities. Theoretically, the study will show how supply chain cooperation is key to humanitarian responses, thus improving effectiveness of HSC when put into practice. Policymakers can use these findings to develop a standard framework of how humanitarian organisations should collectively respond to disasters. Keywords: cyclone; humanitarian logistics; relief operations; supply chain; supply chain cooperation.
- Full Text:
- Date Issued: 2021
- Authors: Chari, Felix , Muzinda, Ozwell , Novukela, Cawe , Ngcamu, Bethuel S.
- Date: 2021
- Subjects: Cyclone damage Business logistics Article
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/11260/7155 , vital:53076 , xlink:href="https://doi.org/10.4102/jtscm.v15i0.532"
- Description: Background: The increased frequency of occurrence and complexity of disasters, the world over, have called for increased cooperation amongst stakeholders to deliver humanitarian aid. Objectives: This study came as a result of the growing interest focussed on creating and implementing cooperation to facilitate management of supply chain-related activities in the humanitarian sector. This study therefore sought to gain a better understanding of the effectiveness of supply chain cooperation in aid delivery performance variables, specifically in the context of Cyclone Idai humanitarian relief operations in Zimbabwe. Method: A pragmatic research paradigm was adopted, where the researchers took a mixed approach informed by both quantitative and qualitative research tools. Results: Findings of this study show a significant and positive impact of humanitarian supply chain (HSC) cooperation in achieving output, resource and flexibility performance in the delivery of aid. These findings will change the shape of humanitarian response to have more cooperation amongst organisations rather than responding as single entities. Conclusion: This study will therefore contribute to how humanitarian organisations improve their approach to future disasters through cooperation in their supply chain activities. Theoretically, the study will show how supply chain cooperation is key to humanitarian responses, thus improving effectiveness of HSC when put into practice. Policymakers can use these findings to develop a standard framework of how humanitarian organisations should collectively respond to disasters. Keywords: cyclone; humanitarian logistics; relief operations; supply chain; supply chain cooperation.
- Full Text:
- Date Issued: 2021
The effects of the composition and structure of quantum dots combined with cobalt phthalocyanine and an aptamer on the electrochemical detection of prostate specific antigen
- Nxele, Siphesihle R, Nyokong, Tebello
- Authors: Nxele, Siphesihle R , Nyokong, Tebello
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/185002 , vital:44315 , xlink:href="https://doi.org/10.1016/j.dyepig.2021.109407"
- Description: The ability to functionalize and modify graphene-based quantum dots has also allowed for the tuning of their activity in different applications. A comparative study is carried out in this work where a prostate specific aptamer (PSA) and cobalt phthalocyanine molecule are combined with graphene quantum dots (GQDs), nitrogen doped graphene quantum dots (NGQDs) and graphitic carbon nitride quantum dots (gCNQDs) in order to determine the effects of quantum dots type (and therefore composition) on the electrocatalytic ability of the sensor to detect the analyte of interest. For the detection of prostate-specific antigen, electrochemical impedance spectroscopy (EIS) is employed to determine detection limits as well as sensitivity and selectivity of the aptasensors. Results showed a good performance of all sensors fabricated with the NGQDs based aptasensor showing the best performance with a detection limit of 1.54 pM in EIS as well as negligible interference in mixed samples. This electrode was further verified in spiked human serum samples and good recovery and low detection limits were determined, putting this aptasensor in good stead as a reliable, efficient PSA aptasensor.
- Full Text:
- Date Issued: 2021
- Authors: Nxele, Siphesihle R , Nyokong, Tebello
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/185002 , vital:44315 , xlink:href="https://doi.org/10.1016/j.dyepig.2021.109407"
- Description: The ability to functionalize and modify graphene-based quantum dots has also allowed for the tuning of their activity in different applications. A comparative study is carried out in this work where a prostate specific aptamer (PSA) and cobalt phthalocyanine molecule are combined with graphene quantum dots (GQDs), nitrogen doped graphene quantum dots (NGQDs) and graphitic carbon nitride quantum dots (gCNQDs) in order to determine the effects of quantum dots type (and therefore composition) on the electrocatalytic ability of the sensor to detect the analyte of interest. For the detection of prostate-specific antigen, electrochemical impedance spectroscopy (EIS) is employed to determine detection limits as well as sensitivity and selectivity of the aptasensors. Results showed a good performance of all sensors fabricated with the NGQDs based aptasensor showing the best performance with a detection limit of 1.54 pM in EIS as well as negligible interference in mixed samples. This electrode was further verified in spiked human serum samples and good recovery and low detection limits were determined, putting this aptasensor in good stead as a reliable, efficient PSA aptasensor.
- Full Text:
- Date Issued: 2021
The electrocatalytic response of metallophthalocyanines when clicked to electrodes and to nanomaterials
- Authors: Mpeta, Lekhetho Simon
- Date: 2021
- Subjects: Phthalocyanines , Nanostructured materials , Electrocatalysis , Nanoparticles , Environmental chemistry , Electrodes , Organic wastes -- Purification
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/172191 , vital:42174 , 10.21504/10962/172191
- Description: Conjugates of nanomaterials and metallophthalocyanines (MPcs) have been prepared and their electrocatalytic activity studied. The prepared nanomaterials are zinc oxide and silver nanoparticles, reduced graphene oxide nanosheets and semiconductor quantum dots. The MPcs used in this work are cobalt (II) (1a), manganese(III) (1b) and iron (II) (1c) 2,9(10),16(17),23(24)- tetrakis 4-((4-ethynylbenzyl) oxy) phthalocyaninato, 2,9(10),16(17),23(24)- tetrakis(5-pentyn-oxy) cobalt (II) phthalocyaninato (2), 9(10),16(17),23(24)- tris-[4-tert-butylphenoxy)-2- (4-ethylbezyl-oxy) cobalt (II) phthalocyaninato (3), 9(10),16(17),23(24)- tris-[4-tertbutylphenoxy)-2-(pent-4yn-yloxy)] cobalt (II) phthalocyaninato (4), cobalt (II) (5a) and manganese (III) (5b) 2,9(10),16(17),23(24)- tetrakis [4-(4-(5-chloro-1H-benzo [d]imidazol-2-yl)phenoxy] phthalocyaninato and 9(10),16(17),23(24)- tris tert butyl phenoxy- 2- [4-(4-(5-chloro-1H-benzo[d]imidazole-2-yl)phenoxy] cobalt (II) phthalocyaninato (6). Some of these MPcs (1a, 3 and 4) were directly clicked on azide grafted electrode, while some (1b, 1c, 2, 5a and 5b) were clicked to azide functionalised nanomaterials and then drop-dried on the electrodes. One phthalocyanine (5b) was drop-dried on the electrode then silver nanoparticles were electrodeposited on it taking advantage of metal-N bond. Scanning electrochemical microscopy, voltammetry, chronoamperometry, electrochemical impedance spectroscopy are among electrochemical methods used to characterise modified electrodes. Transmission electron microscopy, X-ray photoelectron spectroscopy, Xray diffractometry, Raman spectroscopy and infrared spectroscopy were employed to study surface functionalities, morphology and topography of the nanomaterials and complexes. Electrocatalytic activity of the developed materials were studied towards oxidation of 2-mercaptoethanol, hydrazine and hydrogen peroxide while the reduction study was based on oxygen and hydrogen peroxide. In general, the conjugates displayed superior catalytic activity when compared to individual materials. Complex 2 alone and when conjugated to zinc oxide nanoparticles were studied for their nonlinear optical behaviour. And the same materials were explored for their hydrazine detection capability. The aim of this study was to develop sensitive, selective and affordable sensors for selected organic waste pollutants. Conjugates were found to achieve the aim of the study compared to when individual materials were employed.
- Full Text:
- Date Issued: 2021
- Authors: Mpeta, Lekhetho Simon
- Date: 2021
- Subjects: Phthalocyanines , Nanostructured materials , Electrocatalysis , Nanoparticles , Environmental chemistry , Electrodes , Organic wastes -- Purification
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/172191 , vital:42174 , 10.21504/10962/172191
- Description: Conjugates of nanomaterials and metallophthalocyanines (MPcs) have been prepared and their electrocatalytic activity studied. The prepared nanomaterials are zinc oxide and silver nanoparticles, reduced graphene oxide nanosheets and semiconductor quantum dots. The MPcs used in this work are cobalt (II) (1a), manganese(III) (1b) and iron (II) (1c) 2,9(10),16(17),23(24)- tetrakis 4-((4-ethynylbenzyl) oxy) phthalocyaninato, 2,9(10),16(17),23(24)- tetrakis(5-pentyn-oxy) cobalt (II) phthalocyaninato (2), 9(10),16(17),23(24)- tris-[4-tert-butylphenoxy)-2- (4-ethylbezyl-oxy) cobalt (II) phthalocyaninato (3), 9(10),16(17),23(24)- tris-[4-tertbutylphenoxy)-2-(pent-4yn-yloxy)] cobalt (II) phthalocyaninato (4), cobalt (II) (5a) and manganese (III) (5b) 2,9(10),16(17),23(24)- tetrakis [4-(4-(5-chloro-1H-benzo [d]imidazol-2-yl)phenoxy] phthalocyaninato and 9(10),16(17),23(24)- tris tert butyl phenoxy- 2- [4-(4-(5-chloro-1H-benzo[d]imidazole-2-yl)phenoxy] cobalt (II) phthalocyaninato (6). Some of these MPcs (1a, 3 and 4) were directly clicked on azide grafted electrode, while some (1b, 1c, 2, 5a and 5b) were clicked to azide functionalised nanomaterials and then drop-dried on the electrodes. One phthalocyanine (5b) was drop-dried on the electrode then silver nanoparticles were electrodeposited on it taking advantage of metal-N bond. Scanning electrochemical microscopy, voltammetry, chronoamperometry, electrochemical impedance spectroscopy are among electrochemical methods used to characterise modified electrodes. Transmission electron microscopy, X-ray photoelectron spectroscopy, Xray diffractometry, Raman spectroscopy and infrared spectroscopy were employed to study surface functionalities, morphology and topography of the nanomaterials and complexes. Electrocatalytic activity of the developed materials were studied towards oxidation of 2-mercaptoethanol, hydrazine and hydrogen peroxide while the reduction study was based on oxygen and hydrogen peroxide. In general, the conjugates displayed superior catalytic activity when compared to individual materials. Complex 2 alone and when conjugated to zinc oxide nanoparticles were studied for their nonlinear optical behaviour. And the same materials were explored for their hydrazine detection capability. The aim of this study was to develop sensitive, selective and affordable sensors for selected organic waste pollutants. Conjugates were found to achieve the aim of the study compared to when individual materials were employed.
- Full Text:
- Date Issued: 2021
The electrochemical detection of prostate specific antigen on glassy carbon electrode modified with combinations of graphene quantum dots, cobalt phthalocyanine and an aptamer
- Nxele, Siphesihle R, Nyokong, Tebello
- Authors: Nxele, Siphesihle R , Nyokong, Tebello
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/185013 , vital:44316 , xlink:href="https://doi.org/10.1016/j.jinorgbio.2021.111462"
- Description: Herein, a novel aptasensor is developed for the electrochemical detection of prostate specific antigen (PSA) on electrode surfaces modified using various combinations of a Cobalt phthalocyanine (CoPc), an aptamer and graphene quantum dots (GQDs). Electrochemical impedance spectroscopy (EIS) as well as differential pulse voltammetry (DPV) are employed for the detection of PSA. In both analytical techniques, linear calibration curves were observed at a concentration range of 1.2–2.0 pM. The glassy carbon electrode where CoPc and GQDs are placed on the electrode when non-covalently linked followed by addition of the aptamer (GQDs-CoPc(ππ)-aptamer (sequential)) showed the best performance with a limit of detection (LoD) as low as 0.66 pM when using DPV. The detection limits were much lower than the dangerous levels reported for PSA in males tested for prostate cancer. This electrode showed selectivity for PSA in the presence of bovine serum albumin, glucose and L-cysteine. The aptasensor showed good stability, reproducibility and repeatability, deeming it a promising early detection device for prostate cancer.
- Full Text:
- Date Issued: 2021
- Authors: Nxele, Siphesihle R , Nyokong, Tebello
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/185013 , vital:44316 , xlink:href="https://doi.org/10.1016/j.jinorgbio.2021.111462"
- Description: Herein, a novel aptasensor is developed for the electrochemical detection of prostate specific antigen (PSA) on electrode surfaces modified using various combinations of a Cobalt phthalocyanine (CoPc), an aptamer and graphene quantum dots (GQDs). Electrochemical impedance spectroscopy (EIS) as well as differential pulse voltammetry (DPV) are employed for the detection of PSA. In both analytical techniques, linear calibration curves were observed at a concentration range of 1.2–2.0 pM. The glassy carbon electrode where CoPc and GQDs are placed on the electrode when non-covalently linked followed by addition of the aptamer (GQDs-CoPc(ππ)-aptamer (sequential)) showed the best performance with a limit of detection (LoD) as low as 0.66 pM when using DPV. The detection limits were much lower than the dangerous levels reported for PSA in males tested for prostate cancer. This electrode showed selectivity for PSA in the presence of bovine serum albumin, glucose and L-cysteine. The aptasensor showed good stability, reproducibility and repeatability, deeming it a promising early detection device for prostate cancer.
- Full Text:
- Date Issued: 2021
The hermeneutics of recovery
- Kong, Camillia, Campbell, Megan, Kpobi, Lily, Swartz, Leslie, Atuire, Caesar
- Authors: Kong, Camillia , Campbell, Megan , Kpobi, Lily , Swartz, Leslie , Atuire, Caesar
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/302554 , vital:58207 , xlink:href="https://doi.org/10.1177/13634615211000549"
- Description: The widespread use of faith-based and traditional healing for mental disorders within African contexts is well known. However, normative responses tend to fall within two camps: on one hand, those oriented towards the biomedical model of psychiatry stress the abuses and superstition of such healing, whilst critics adopting a more ‘local’ perspective have fundamentally challenged the universalist claims of biomedical diagnostic categories and psychiatric treatments. What seemingly emerges is a dichotomy between those who endorse more ‘universalist’ or ‘relativist’ approaches as an analytical lens to the challenges of the diverse healing strands within African contexts. In this article, we draw upon the resources of philosophy and existing empirical work to challenge the notion that constructive dialogue cannot be had between seemingly incommensurable healing practices in global mental health. First, we suggest the need for much-needed conceptual clarity to explore the hermeneutics of meaning, practice, and understanding, in order to forge constructive normative pathways of dialogue between seemingly incommensurable values and conceptual schemas around mental disorder and healing. Second, we contextualise the complex motives to emphasise difference amongst health practitioners within a competitive healing economy. Finally, we appeal to the notion of recovery as discovery as a fruitful conceptual framework which incorporates dialogue, comparative evaluation, and cross-cultural enrichment across divergent conceptualisations of mental health.
- Full Text:
- Date Issued: 2021
- Authors: Kong, Camillia , Campbell, Megan , Kpobi, Lily , Swartz, Leslie , Atuire, Caesar
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/302554 , vital:58207 , xlink:href="https://doi.org/10.1177/13634615211000549"
- Description: The widespread use of faith-based and traditional healing for mental disorders within African contexts is well known. However, normative responses tend to fall within two camps: on one hand, those oriented towards the biomedical model of psychiatry stress the abuses and superstition of such healing, whilst critics adopting a more ‘local’ perspective have fundamentally challenged the universalist claims of biomedical diagnostic categories and psychiatric treatments. What seemingly emerges is a dichotomy between those who endorse more ‘universalist’ or ‘relativist’ approaches as an analytical lens to the challenges of the diverse healing strands within African contexts. In this article, we draw upon the resources of philosophy and existing empirical work to challenge the notion that constructive dialogue cannot be had between seemingly incommensurable healing practices in global mental health. First, we suggest the need for much-needed conceptual clarity to explore the hermeneutics of meaning, practice, and understanding, in order to forge constructive normative pathways of dialogue between seemingly incommensurable values and conceptual schemas around mental disorder and healing. Second, we contextualise the complex motives to emphasise difference amongst health practitioners within a competitive healing economy. Finally, we appeal to the notion of recovery as discovery as a fruitful conceptual framework which incorporates dialogue, comparative evaluation, and cross-cultural enrichment across divergent conceptualisations of mental health.
- Full Text:
- Date Issued: 2021
The impact of labour legislation on selected small firms in Mbombela (Nelspruit)
- Authors: Dlamini, Sikhulile Blessing
- Date: 2021
- Subjects: Labor laws and legislation -- South Africa , Small business -- Law and legislation-- South Afric , Small business -- South Africa -- Mbombela -- Case studies
- Language: English
- Type: text , Thesis , Masters , MSocSci
- Identifier: http://hdl.handle.net/10962/170781 , vital:41959
- Description: This study uses the theoretical framework of industrial relations pluralism, to study and analyse the impacts of labour legislation on six small firms (employing less than 50 workers) based in Mbombela (formerly Nelspruit), Mpumalanga province, South Africa. The analysis is based on the viewpoints of six managers and how they see the impacts of labour legislation on their respective firms. The analysis is aided by utilising theory and literature to make sense of the manager perspectives on the topic. Also, utilising a qualitative research design to collect and analyse the data, the study presents diverse findings in terms of how the participants perceived and experienced certain types of legislation. Some managers believed that the benefits of labour legislation outweighed the costs. While others believed the exact opposite. At an overall level, the study revealed that most of the participants were not as severely affected by labour legislation as might be expected; given the scarcity of resources in most small firms. This was partly because of various coping strategies and practices (mostly involving the use of informal procedures) that were adopted by the firms. Also, some small firms who aimed at expanding their businesses strategised to adopt some formal procedures and practices in order to easily absorb labour legislation and subsequently mordenise their businesses in the process. While a few firms persisted with more informal customs as they appeared cost-effective and necessary in their particular market positioning.
- Full Text:
- Date Issued: 2021
- Authors: Dlamini, Sikhulile Blessing
- Date: 2021
- Subjects: Labor laws and legislation -- South Africa , Small business -- Law and legislation-- South Afric , Small business -- South Africa -- Mbombela -- Case studies
- Language: English
- Type: text , Thesis , Masters , MSocSci
- Identifier: http://hdl.handle.net/10962/170781 , vital:41959
- Description: This study uses the theoretical framework of industrial relations pluralism, to study and analyse the impacts of labour legislation on six small firms (employing less than 50 workers) based in Mbombela (formerly Nelspruit), Mpumalanga province, South Africa. The analysis is based on the viewpoints of six managers and how they see the impacts of labour legislation on their respective firms. The analysis is aided by utilising theory and literature to make sense of the manager perspectives on the topic. Also, utilising a qualitative research design to collect and analyse the data, the study presents diverse findings in terms of how the participants perceived and experienced certain types of legislation. Some managers believed that the benefits of labour legislation outweighed the costs. While others believed the exact opposite. At an overall level, the study revealed that most of the participants were not as severely affected by labour legislation as might be expected; given the scarcity of resources in most small firms. This was partly because of various coping strategies and practices (mostly involving the use of informal procedures) that were adopted by the firms. Also, some small firms who aimed at expanding their businesses strategised to adopt some formal procedures and practices in order to easily absorb labour legislation and subsequently mordenise their businesses in the process. While a few firms persisted with more informal customs as they appeared cost-effective and necessary in their particular market positioning.
- Full Text:
- Date Issued: 2021
The impact of poverty reduction strategies during COVID-19 in South Africa
- Authors: Maxwell, Sentiwe
- Date: 2021
- Subjects: Poverty , Service delivery
- Language: English
- Type: lecture , text
- Identifier: http://hdl.handle.net/11260/6307 , vital:45366
- Description: This article focuses on investigating the impact of poverty reduction strategies during Covid 19 in improving the quality of lives of the people in our local municipalities, in relation to interventions that have been implemented by the South African government to address poverty. The purpose of the article is to understand the situation in our municipalities and come up with recommendations that will assist government to enhance delivery of poverty reduction strategy in order to improve the quality of life of the rural poor communities. The findings on this article show that; whilst significant progress has been made to address poverty through policy and legal frameworks and through implementation of poverty reduction strategies and programmes, there is a general consensus in literature that poverty is still widespread in South Africa and that activities put in place to reduce and eradicate it are not sufficiently translating into required outputs necessary for desired outcomes which ultimately impact on poverty. The study has identified the gaps that exist in service delivery as well as the challenges faced by government in effectively impacting on poverty through its poverty reduction programmes. Based on the findings the study has made recommendations that will assist government to enhance service delivery so that poverty reduction strategies are conducted in an effective and efficient, integrated and coordinated manner which will cause government to achieve its desired outcomes.
- Full Text:
- Date Issued: 2021
- Authors: Maxwell, Sentiwe
- Date: 2021
- Subjects: Poverty , Service delivery
- Language: English
- Type: lecture , text
- Identifier: http://hdl.handle.net/11260/6307 , vital:45366
- Description: This article focuses on investigating the impact of poverty reduction strategies during Covid 19 in improving the quality of lives of the people in our local municipalities, in relation to interventions that have been implemented by the South African government to address poverty. The purpose of the article is to understand the situation in our municipalities and come up with recommendations that will assist government to enhance delivery of poverty reduction strategy in order to improve the quality of life of the rural poor communities. The findings on this article show that; whilst significant progress has been made to address poverty through policy and legal frameworks and through implementation of poverty reduction strategies and programmes, there is a general consensus in literature that poverty is still widespread in South Africa and that activities put in place to reduce and eradicate it are not sufficiently translating into required outputs necessary for desired outcomes which ultimately impact on poverty. The study has identified the gaps that exist in service delivery as well as the challenges faced by government in effectively impacting on poverty through its poverty reduction programmes. Based on the findings the study has made recommendations that will assist government to enhance service delivery so that poverty reduction strategies are conducted in an effective and efficient, integrated and coordinated manner which will cause government to achieve its desired outcomes.
- Full Text:
- Date Issued: 2021
The impact of the COVID-19 pandemic on accessing HIV care: A case report
- Authors: Kaswa, Ramprakash
- Date: 2021
- Subjects: COVID-19 Pandemic, 2020- HIV (Viruses) Diseases Article
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/11260/7291 , vital:53107 , xlink:href="https://doi.org/10.4102/safp.v63i1.5344"
- Description: The coronavirus disease 2019 (COVID-19) pandemic has had an enormous impact on the provision of human immunodeficiency virus (HIV) services amongst people living with HIV. Many people have adopted different health-seeking behaviour in alignment with the lockdown provisions during the COVID-19 pandemic. These lockdown regulations have had a huge impact on healthcare access for people on chronic medication. The disruption of antiretroviral therapy (ART) has a profound effect on HIV-associated morbidity and mortality. The impact on HIV programmes as a result of the interruption in ART could be bigger than the HIV pandemic alone. Keywords: COVID-19; pandemic; HIV; ART; lockdown; morbidity and mortality.
- Full Text:
- Date Issued: 2021
- Authors: Kaswa, Ramprakash
- Date: 2021
- Subjects: COVID-19 Pandemic, 2020- HIV (Viruses) Diseases Article
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/11260/7291 , vital:53107 , xlink:href="https://doi.org/10.4102/safp.v63i1.5344"
- Description: The coronavirus disease 2019 (COVID-19) pandemic has had an enormous impact on the provision of human immunodeficiency virus (HIV) services amongst people living with HIV. Many people have adopted different health-seeking behaviour in alignment with the lockdown provisions during the COVID-19 pandemic. These lockdown regulations have had a huge impact on healthcare access for people on chronic medication. The disruption of antiretroviral therapy (ART) has a profound effect on HIV-associated morbidity and mortality. The impact on HIV programmes as a result of the interruption in ART could be bigger than the HIV pandemic alone. Keywords: COVID-19; pandemic; HIV; ART; lockdown; morbidity and mortality.
- Full Text:
- Date Issued: 2021
The improved antibacterial efficiency of a zinc phthalocyanine when embedded on silver nanoparticle modified silica nanofibers
- Mapukata, Sivuyisiwe, Britton, Jonathan, Osifeko, Olawale L, Nyokong, Tebello
- Authors: Mapukata, Sivuyisiwe , Britton, Jonathan , Osifeko, Olawale L , Nyokong, Tebello
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/185784 , vital:44423 , xlink:href="https://doi.org/10.1016/j.pdpdt.2020.102100"
- Description: This work reports on the fabrication and modification of electrospun polymer free silica nanofibers (SiO2 NFs) with the aim of creating heterogeneous antibacterial catalysts. The optical and photophysical properties of the obtained NFs i.e. bare SiO2, Ag-SiO2, Pc-SiO2 and Pc@Ag-SiO2 NFs (Pc = phthalocyanine) were compared and reported. The singlet oxygen quantum yields of the Pc-SiO2 and Pc@Ag-SiO2 NFs were also quantified and found to be 0.08 and 0.12, respectively, in water. All the modified SiO2 NFs were found to possess photoactivity against S. aureus with the most effective being the Pc@Ag-SiO2 NFs due to the synergy between the Pc and Ag nanoparticles. The bare SiO2 NFs do not exhibit any antibacterial activity while the Ag-SiO2 and Pc@Ag-SiO2 NFs were found to also exhibit dark toxicity. The generated photocatalysts are attractive because they are active against bacteria and they are easily retrievable post-application. The nanocatalysts reported herein are therefore feasible candidates for real-life antibacterial applications.
- Full Text:
- Date Issued: 2021
- Authors: Mapukata, Sivuyisiwe , Britton, Jonathan , Osifeko, Olawale L , Nyokong, Tebello
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/185784 , vital:44423 , xlink:href="https://doi.org/10.1016/j.pdpdt.2020.102100"
- Description: This work reports on the fabrication and modification of electrospun polymer free silica nanofibers (SiO2 NFs) with the aim of creating heterogeneous antibacterial catalysts. The optical and photophysical properties of the obtained NFs i.e. bare SiO2, Ag-SiO2, Pc-SiO2 and Pc@Ag-SiO2 NFs (Pc = phthalocyanine) were compared and reported. The singlet oxygen quantum yields of the Pc-SiO2 and Pc@Ag-SiO2 NFs were also quantified and found to be 0.08 and 0.12, respectively, in water. All the modified SiO2 NFs were found to possess photoactivity against S. aureus with the most effective being the Pc@Ag-SiO2 NFs due to the synergy between the Pc and Ag nanoparticles. The bare SiO2 NFs do not exhibit any antibacterial activity while the Ag-SiO2 and Pc@Ag-SiO2 NFs were found to also exhibit dark toxicity. The generated photocatalysts are attractive because they are active against bacteria and they are easily retrievable post-application. The nanocatalysts reported herein are therefore feasible candidates for real-life antibacterial applications.
- Full Text:
- Date Issued: 2021
The influence of biophysical and socio-economic factors on the effectiveness of private land conservation areas in preventing natural land cover loss across South Africa
- Shumba, Tafadzwa, de Vos, Alta, Biggs, Reinette, Esler, Karen J, Clements, Hayley S
- Authors: Shumba, Tafadzwa , de Vos, Alta , Biggs, Reinette , Esler, Karen J , Clements, Hayley S
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/415940 , vital:71302 , xlink:href="https://doi.org/10.1016/j.gecco.2021.e01670"
- Description: There is increasing interest in the potential of private land conservation areas (PLCAs) as a complementary biodiversity conservation strategy to state-owned protected areas. However, there is limited understanding of how the diverse social-ecological contexts of PLCAs influence their effectiveness in conserving biodiversity. Here, we investigated how the effectiveness of South African PLCAs in conserving biodiversity varied across social-ecological contexts, using natural land cover as a proxy. Social-ecological contexts were represented by biophysical and legal factors (distance to towns and roads, elevation, slope, terrain ruggedness, rainfall, PLCA size, distance to state-owned national parks, and presence of legal protection) and, for a subset of commercially-operated PLCAs, management factors (adopted business model, and profitability).
- Full Text:
- Date Issued: 2021
- Authors: Shumba, Tafadzwa , de Vos, Alta , Biggs, Reinette , Esler, Karen J , Clements, Hayley S
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/415940 , vital:71302 , xlink:href="https://doi.org/10.1016/j.gecco.2021.e01670"
- Description: There is increasing interest in the potential of private land conservation areas (PLCAs) as a complementary biodiversity conservation strategy to state-owned protected areas. However, there is limited understanding of how the diverse social-ecological contexts of PLCAs influence their effectiveness in conserving biodiversity. Here, we investigated how the effectiveness of South African PLCAs in conserving biodiversity varied across social-ecological contexts, using natural land cover as a proxy. Social-ecological contexts were represented by biophysical and legal factors (distance to towns and roads, elevation, slope, terrain ruggedness, rainfall, PLCA size, distance to state-owned national parks, and presence of legal protection) and, for a subset of commercially-operated PLCAs, management factors (adopted business model, and profitability).
- Full Text:
- Date Issued: 2021
The influence of citrus orchard age on the ecology of entomopathogenic fungi and nematodes
- Albertyn, Sonnica, Moore, Sean D, Marsberg, Tamryn, Coombes, Candice A, Hill, Martin P
- Authors: Albertyn, Sonnica , Moore, Sean D , Marsberg, Tamryn , Coombes, Candice A , Hill, Martin P
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/417790 , vital:71486 , xlink:href="https://doi.org/10.1080/09583157.2020.1830949"
- Description: A three-year survey of the ecology of entomopathogenic nematodes (EPN) and entomopathogenic fungi (EPF) was undertaken on soils from citrus orchards of different ages to determine the influence of orchard age on the ecology of entomopathogenic fungi and nematodes. The influence of mulch and irrigation method on the occurrence of EPN and EPF was also determined. Most of the isolates recovered (n = 810) were Beauveria sp. (87.88% of all isolates), followed by Metarhizium sp. (11.87% of all isolates). Only 0.24% of soil samples collected during this study tested positive for EPN. All EPN isolates recovered were Heterorhabditis bacteriophora. No significant differences in EPF occurrence were recorded between orchards under drip and micro-sprinkler irrigation. EPF occurrence was significantly lower (P = 0.016) in orchards covered by mulch (31.85% ± 2.07% occurrence) than in orchards with no covering (38.57% ± 1.57% occurrence). EPF occurrence of 40.33 ± 2.13% was highest in non-bearing orchards, followed by mature orchards (nine years or older) (36.76 ± 2.05% of samples) with the lowest EPF occurrence of 25.30 ± 2.02% reported in juvenile orchards (four to eight years old). Juvenile orchards sustain significantly less EPF than mature and non-bearing orchards because of the combined negative impact of less favourable environmental conditions (lower shade density) and fungicide applications.
- Full Text:
- Date Issued: 2021
- Authors: Albertyn, Sonnica , Moore, Sean D , Marsberg, Tamryn , Coombes, Candice A , Hill, Martin P
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/417790 , vital:71486 , xlink:href="https://doi.org/10.1080/09583157.2020.1830949"
- Description: A three-year survey of the ecology of entomopathogenic nematodes (EPN) and entomopathogenic fungi (EPF) was undertaken on soils from citrus orchards of different ages to determine the influence of orchard age on the ecology of entomopathogenic fungi and nematodes. The influence of mulch and irrigation method on the occurrence of EPN and EPF was also determined. Most of the isolates recovered (n = 810) were Beauveria sp. (87.88% of all isolates), followed by Metarhizium sp. (11.87% of all isolates). Only 0.24% of soil samples collected during this study tested positive for EPN. All EPN isolates recovered were Heterorhabditis bacteriophora. No significant differences in EPF occurrence were recorded between orchards under drip and micro-sprinkler irrigation. EPF occurrence was significantly lower (P = 0.016) in orchards covered by mulch (31.85% ± 2.07% occurrence) than in orchards with no covering (38.57% ± 1.57% occurrence). EPF occurrence of 40.33 ± 2.13% was highest in non-bearing orchards, followed by mature orchards (nine years or older) (36.76 ± 2.05% of samples) with the lowest EPF occurrence of 25.30 ± 2.02% reported in juvenile orchards (four to eight years old). Juvenile orchards sustain significantly less EPF than mature and non-bearing orchards because of the combined negative impact of less favourable environmental conditions (lower shade density) and fungicide applications.
- Full Text:
- Date Issued: 2021
The invasion ecology of Pontederia cordata L. (Pontederiaceae) in South Africa
- Authors: Wansell, Sage Nora-Lee
- Date: 2021
- Subjects: Plant invsions -- South AFrica , Invasive plants -- Ecology -- South Africa , Pontederiaceae -- South AFrica
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/172433 , vital:42200
- Description: Pontederia cordata L. (Pontederiaceae) is a tristylous invasive macrophyte – originating from North and South America – that has caused detrimental environmental, agricultural and socio-economic impacts in South Africa (SA). This novel study investigates the invasive ecology of P. cordata in SA by determining population genetics, pollination ecology and floral traits. Preliminary field surveys suggest that only one of three tristylous forms of P. cordata is invading SA and no seeds have been observed in any invasive populations. This study therefore determined the population genetics, mode of spread of P. cordata in SA and possible reasons for the lack of seed production, as well as providing suggestions for future control and management strategies. Inter Simple Sequence Repeats of leaf samples from invasive populations in SA and the native range of the United States of America (USA) were performed to determine the population genetics of P. cordata. The clarification of population structure of an alien invasive plant can provide insight into founder effects, introduction events and modes of spread and is important for the development of management plans such as biological control. Results from the genetic analyses indicated that P. cordata populations have low genetic diversity within and amongst invasive populations in comparison to native populations. This suggests that high gene flow and sexual reproduction is not present in invasive populations, and that only a single or very few introductory events have occurred in SA. Furthermore, invasive P. cordata populations shared the highest genetic similarity with native samples from Belle Haven, Virginia, USA, and thus further sampling and future genetic surveys should be conducted in this area to identify source populations to survey for potential biological control agents. Following these findings, I investigated whether sexual reproduction and seed production is absent from invasive P. cordata populations in SA as speculated. Floral traits from populations throughout all the invaded provinces were measured and, along with pollen grain measurements, it was determined that only short-morphed plants are present in SA. It was speculated that the absence of native pollinators in the invasive range may be responsible for the absence of sexual reproduction. However, a pollination study confirmed the presence of generalist insect pollinators. Thereafter, artificial pollination experiments on 8 865 flowers were conducted to determine whether an incompatibility system was present which prevented seed production. No seeds were produced and it was concluded that illegitimate pollination of the short-morphed plants prevented seed production and rhizomes are responsible for the invasion of P. cordata throughout SA. The implications of these findings and possible management strategies such as biological control is discussed in Chapter 4. These findings suggest that control programmes should target the plants rhizomes to prevent and reduce spread. Preventing the introduction of medium- and long-morphed plants into SA is crucial to prevent P. cordata from producing seeds and intensifying invasion further through both asexual and sexual spread.
- Full Text:
- Date Issued: 2021
- Authors: Wansell, Sage Nora-Lee
- Date: 2021
- Subjects: Plant invsions -- South AFrica , Invasive plants -- Ecology -- South Africa , Pontederiaceae -- South AFrica
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/172433 , vital:42200
- Description: Pontederia cordata L. (Pontederiaceae) is a tristylous invasive macrophyte – originating from North and South America – that has caused detrimental environmental, agricultural and socio-economic impacts in South Africa (SA). This novel study investigates the invasive ecology of P. cordata in SA by determining population genetics, pollination ecology and floral traits. Preliminary field surveys suggest that only one of three tristylous forms of P. cordata is invading SA and no seeds have been observed in any invasive populations. This study therefore determined the population genetics, mode of spread of P. cordata in SA and possible reasons for the lack of seed production, as well as providing suggestions for future control and management strategies. Inter Simple Sequence Repeats of leaf samples from invasive populations in SA and the native range of the United States of America (USA) were performed to determine the population genetics of P. cordata. The clarification of population structure of an alien invasive plant can provide insight into founder effects, introduction events and modes of spread and is important for the development of management plans such as biological control. Results from the genetic analyses indicated that P. cordata populations have low genetic diversity within and amongst invasive populations in comparison to native populations. This suggests that high gene flow and sexual reproduction is not present in invasive populations, and that only a single or very few introductory events have occurred in SA. Furthermore, invasive P. cordata populations shared the highest genetic similarity with native samples from Belle Haven, Virginia, USA, and thus further sampling and future genetic surveys should be conducted in this area to identify source populations to survey for potential biological control agents. Following these findings, I investigated whether sexual reproduction and seed production is absent from invasive P. cordata populations in SA as speculated. Floral traits from populations throughout all the invaded provinces were measured and, along with pollen grain measurements, it was determined that only short-morphed plants are present in SA. It was speculated that the absence of native pollinators in the invasive range may be responsible for the absence of sexual reproduction. However, a pollination study confirmed the presence of generalist insect pollinators. Thereafter, artificial pollination experiments on 8 865 flowers were conducted to determine whether an incompatibility system was present which prevented seed production. No seeds were produced and it was concluded that illegitimate pollination of the short-morphed plants prevented seed production and rhizomes are responsible for the invasion of P. cordata throughout SA. The implications of these findings and possible management strategies such as biological control is discussed in Chapter 4. These findings suggest that control programmes should target the plants rhizomes to prevent and reduce spread. Preventing the introduction of medium- and long-morphed plants into SA is crucial to prevent P. cordata from producing seeds and intensifying invasion further through both asexual and sexual spread.
- Full Text:
- Date Issued: 2021
The nature of violence in South African universities African universities: The politics of process
- Mutongoza, Bonginkosi Hardy https://orcid.org/0000-0002-2939-1274
- Authors: Mutongoza, Bonginkosi Hardy https://orcid.org/0000-0002-2939-1274
- Date: 2021
- Subjects: Education, Higher -- Political aspects , Universities and colleges -- South Africa , Campus violence
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10353/27909 , vital:70816
- Description: The high levels of violence that plague South Africa’s universities are symptomatic of an education system that is under attack, with institutions of higher learning not reflecting the peacefulness and safety which are oftentimes associated with the pursuit of learning. While violence in societies and educational institutions globally continues to intensify in viciousness and frequency, this is especially worrisome for South Africa, a country regarded as one of the most violent in the world. South African education institutions are admittedly extremely violent, yet there are relatively few mechanisms to enable the verification of trends in violence, or to cross-reference and compare incidents, thus making the reduction of violence problematic. The contention is that the general outlook of violence at educational institutions appears to echo the relentless violence which haunts South African communities in general. Against this background, the current study sought to explore the nature of violence in South African universities. To achieve this, the study was guided by an exploration of student and staff experiences of violence in universities, the causes of violence in such sites, and the recording thereof. Underpinned by a pragmatist paradigm, this study utilised a mixed-methods approach to ‘get under the skin’ of the problem of violence in universities. Within the mixed-methods approach, the study employed a single-phase convergent design, which enabled the researcher to reach comprehensive conclusions on violence in universities, by merging and comparing qualitative and quantitative datasets. In the quantitative phase of the study, a simple random sampling technique was used to select a total of 1 776 students and 250 staff, while 32 students and four staff were conveniently sampled during the qualitative phase. The data for this study were collected using an online survey in the quantitative phase, and semi-structured interviews and document reviews in the qualitative phase. The findings of this investigation revealed that violence happened in six main configurations, namely student-on-student violence, staff-on-student violence, staff-on-staff violence, student-on-staff violence, self-directed violence, and protest-related violence. In addition, the findings revealed diverse causes of violence in universities, chief of which were alcohol and drug abuse, poor security, the abuse of power or authority, impunity, and psychosocial factors, among others. Factors that impeded the recording of violence in universities included the normalisation of violence, a lack of consequences for the perpetrators, a lack of procedural awareness, cronyism and brotherhoods, and a lack of protection from reprisal for reporting perpetrators. The production of violence in South African universities was also found to be significantly shaped by wider structures that included sexuality, gender, age, socioeconomic status, and race and ethnicity. These structures were found to be prominent in increasing the likelihood of violence being perpetrated. Based on the reported findings, the study moved to recommend that, in order to reduce experiences of violence in South African universities, institutions adopt multidimensional approaches to combatting this scourge. The fact that violence was noted to occur in multiple configurations, means multiple viewpoints are required to reduce and ultimately combat it. This calls for a multi-stakeholder approach that transcends a reliance on the traditional university policymakers, and a concerted consultative process to formulate and renew policies that can help to address university violence. The study further recommended that reporting structures be decentralised at universities, in a bid to improve the smoothness of related processes. In this respect, it will be essential for universities to consider setting up anonymous reporting platforms online, to move with the times and ensure more urgent responses, as opposed to a continued reliance on present systems that are replete with red tape. Additionally, universities may consider outsourcing divisions that deal with violence reporting, to minimise conflicts of interest when dealing with such cases. The researcher concluded that violence in universities threatens the very purpose of tertiary education – members of the university community must be able to freely pursue their aspirations in peaceful environments. As such, for as long as campuses experience violence in any of its varied forms, a proverbial dark cloud will forever frustrate the quest for quality and transformative education that has the potential to reverse-engineer inequality, poverty, and underdevelopment in South Africa, as contemplated in various development plans. , Thesis (PhD) -- Faculty of Education, 2021
- Full Text:
- Date Issued: 2021
- Authors: Mutongoza, Bonginkosi Hardy https://orcid.org/0000-0002-2939-1274
- Date: 2021
- Subjects: Education, Higher -- Political aspects , Universities and colleges -- South Africa , Campus violence
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10353/27909 , vital:70816
- Description: The high levels of violence that plague South Africa’s universities are symptomatic of an education system that is under attack, with institutions of higher learning not reflecting the peacefulness and safety which are oftentimes associated with the pursuit of learning. While violence in societies and educational institutions globally continues to intensify in viciousness and frequency, this is especially worrisome for South Africa, a country regarded as one of the most violent in the world. South African education institutions are admittedly extremely violent, yet there are relatively few mechanisms to enable the verification of trends in violence, or to cross-reference and compare incidents, thus making the reduction of violence problematic. The contention is that the general outlook of violence at educational institutions appears to echo the relentless violence which haunts South African communities in general. Against this background, the current study sought to explore the nature of violence in South African universities. To achieve this, the study was guided by an exploration of student and staff experiences of violence in universities, the causes of violence in such sites, and the recording thereof. Underpinned by a pragmatist paradigm, this study utilised a mixed-methods approach to ‘get under the skin’ of the problem of violence in universities. Within the mixed-methods approach, the study employed a single-phase convergent design, which enabled the researcher to reach comprehensive conclusions on violence in universities, by merging and comparing qualitative and quantitative datasets. In the quantitative phase of the study, a simple random sampling technique was used to select a total of 1 776 students and 250 staff, while 32 students and four staff were conveniently sampled during the qualitative phase. The data for this study were collected using an online survey in the quantitative phase, and semi-structured interviews and document reviews in the qualitative phase. The findings of this investigation revealed that violence happened in six main configurations, namely student-on-student violence, staff-on-student violence, staff-on-staff violence, student-on-staff violence, self-directed violence, and protest-related violence. In addition, the findings revealed diverse causes of violence in universities, chief of which were alcohol and drug abuse, poor security, the abuse of power or authority, impunity, and psychosocial factors, among others. Factors that impeded the recording of violence in universities included the normalisation of violence, a lack of consequences for the perpetrators, a lack of procedural awareness, cronyism and brotherhoods, and a lack of protection from reprisal for reporting perpetrators. The production of violence in South African universities was also found to be significantly shaped by wider structures that included sexuality, gender, age, socioeconomic status, and race and ethnicity. These structures were found to be prominent in increasing the likelihood of violence being perpetrated. Based on the reported findings, the study moved to recommend that, in order to reduce experiences of violence in South African universities, institutions adopt multidimensional approaches to combatting this scourge. The fact that violence was noted to occur in multiple configurations, means multiple viewpoints are required to reduce and ultimately combat it. This calls for a multi-stakeholder approach that transcends a reliance on the traditional university policymakers, and a concerted consultative process to formulate and renew policies that can help to address university violence. The study further recommended that reporting structures be decentralised at universities, in a bid to improve the smoothness of related processes. In this respect, it will be essential for universities to consider setting up anonymous reporting platforms online, to move with the times and ensure more urgent responses, as opposed to a continued reliance on present systems that are replete with red tape. Additionally, universities may consider outsourcing divisions that deal with violence reporting, to minimise conflicts of interest when dealing with such cases. The researcher concluded that violence in universities threatens the very purpose of tertiary education – members of the university community must be able to freely pursue their aspirations in peaceful environments. As such, for as long as campuses experience violence in any of its varied forms, a proverbial dark cloud will forever frustrate the quest for quality and transformative education that has the potential to reverse-engineer inequality, poverty, and underdevelopment in South Africa, as contemplated in various development plans. , Thesis (PhD) -- Faculty of Education, 2021
- Full Text:
- Date Issued: 2021
The perception of police officers towards corruption in South African police services: a case study of Polokwane cluster policing area in Limpopo Province
- Authors: Rathogwa, Emmah Mufanadzo
- Date: 2021
- Subjects: Corruption , Police corruption , Police misconduct
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10353/27314 , vital:66935
- Description: The 1996 National Crime Prevention Strategy identified corruption within the criminal justice sector as the greatest threat to the governance of security. Police corruption has been a huge obstacle within the South African Police Service’s endeavours to tackle improper activities of police officers. A general definition of corruption is “use of public office for private gain”; this includes bribery and extortion, which involves at least two parties, and other types of malfeasance that a public official can carry out alone, including fraud and embezzlement. The corruption of police officers impinges on the capacity and ability of the entire force in ensuring that all citizens abide by the law. This study explored the perceptions of police officers towards corruption activities in South African Police Services (SAPS) within the Polokwane Cluster (Capricorn District) Policing Area in Limpopo province. In this study, a qualitative research design was used. The researcher used purposive sampling to select participants. For collection of data, semi-structured interviews were used where the researcher interviewed police officers within the Polokwane Cluster Capricorn District Policing Area. The researcher conducted fifty 50 interviews with five police officers from 10 police stations within the Polokwane Cluster Capricorn District Policing Area, namely: Botlokwa, Lebowakgomo, Polokwane,Westernburg, Seshego, Mankweng, Mashashane, Matlala, Mogwadi and Zebediela police stations. In addition, secondary sources were used where the researcher relied on documents from the Independent Police Investigations IPID on statistics on police corruption, among other scales of measurements. For the analysis of data, thematic content analysis was used to analyse the data collected through interviews whilst document analysis was used for analysing data collected from secondary sources. The findings gathered in this study revealed that police corruption is widespread within the Polokwane Cluster Capricorn District Policing Area in Limpopo province due some police officers’ fear of victimisation of their families or loved ones if they expose corrupt acts by other police officers. Furthermore, corruption of the South African Police Services personnel has been reported where potential police recruits are required to pay bribes for them to be placed for the job. Weak leadership within the South African police service and poor policy formulation and implementation have been identified by participants to be some of the main determinants of corruption within the South African Police Services. As a recommendation to counter the adverse effects of police corruption, a number of strategies have been formulated in this study such as the establishment of vibrant anticorruption mechanisms. It is essential for the government to recall passionate former police officials to investigate all the corrupt officials. The South African government should establish a very sophisticated anti-corruption body independent from the SAPS to spearhead the strategy to combat corruption. The recruitment of police personnel should culminate into hiring individuals who would see the police job as a calling and do it passionately. They should firstly target people who choose police related courses are already studying courses in crime investigation from grassroots level. , Thesis (MSoc) -- Faculty of Social Sciences and Humanities, 2021
- Full Text:
- Date Issued: 2021
- Authors: Rathogwa, Emmah Mufanadzo
- Date: 2021
- Subjects: Corruption , Police corruption , Police misconduct
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10353/27314 , vital:66935
- Description: The 1996 National Crime Prevention Strategy identified corruption within the criminal justice sector as the greatest threat to the governance of security. Police corruption has been a huge obstacle within the South African Police Service’s endeavours to tackle improper activities of police officers. A general definition of corruption is “use of public office for private gain”; this includes bribery and extortion, which involves at least two parties, and other types of malfeasance that a public official can carry out alone, including fraud and embezzlement. The corruption of police officers impinges on the capacity and ability of the entire force in ensuring that all citizens abide by the law. This study explored the perceptions of police officers towards corruption activities in South African Police Services (SAPS) within the Polokwane Cluster (Capricorn District) Policing Area in Limpopo province. In this study, a qualitative research design was used. The researcher used purposive sampling to select participants. For collection of data, semi-structured interviews were used where the researcher interviewed police officers within the Polokwane Cluster Capricorn District Policing Area. The researcher conducted fifty 50 interviews with five police officers from 10 police stations within the Polokwane Cluster Capricorn District Policing Area, namely: Botlokwa, Lebowakgomo, Polokwane,Westernburg, Seshego, Mankweng, Mashashane, Matlala, Mogwadi and Zebediela police stations. In addition, secondary sources were used where the researcher relied on documents from the Independent Police Investigations IPID on statistics on police corruption, among other scales of measurements. For the analysis of data, thematic content analysis was used to analyse the data collected through interviews whilst document analysis was used for analysing data collected from secondary sources. The findings gathered in this study revealed that police corruption is widespread within the Polokwane Cluster Capricorn District Policing Area in Limpopo province due some police officers’ fear of victimisation of their families or loved ones if they expose corrupt acts by other police officers. Furthermore, corruption of the South African Police Services personnel has been reported where potential police recruits are required to pay bribes for them to be placed for the job. Weak leadership within the South African police service and poor policy formulation and implementation have been identified by participants to be some of the main determinants of corruption within the South African Police Services. As a recommendation to counter the adverse effects of police corruption, a number of strategies have been formulated in this study such as the establishment of vibrant anticorruption mechanisms. It is essential for the government to recall passionate former police officials to investigate all the corrupt officials. The South African government should establish a very sophisticated anti-corruption body independent from the SAPS to spearhead the strategy to combat corruption. The recruitment of police personnel should culminate into hiring individuals who would see the police job as a calling and do it passionately. They should firstly target people who choose police related courses are already studying courses in crime investigation from grassroots level. , Thesis (MSoc) -- Faculty of Social Sciences and Humanities, 2021
- Full Text:
- Date Issued: 2021
The photodynamic activities of the gold nanoparticle conjugates of phosphorus (V) and gallium (III) A3 meso-triarylcorroles
- Soy, Rodah C, Babu, Balaji, Mack, John, Nyokong, Tebello
- Authors: Soy, Rodah C , Babu, Balaji , Mack, John , Nyokong, Tebello
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/185678 , vital:44409 , xlink:href="https://doi.org/10.1016/j.dyepig.2021.109631"
- Description: The synthesis and characterization of series of P(V) and Ga(III) A3 triarylcorrole complexes with 4-methylthiophenyl (2a, 3a), thien-3-yl (2b, 3b) and thien-2-yl (2c, 3c) meso-groups are reported along with the physicochemical and photodynamic activity properties of the dyes and their gold nanoparticle (AuNP) conjugates. The Ga(III) corrole series have lower fluorescence quantum yields and higher singlet oxygen quantum yields than the analogous P(V) complexes. Upon conjugation to AuNPs, the fluorescence quantum yields of the P(V) and Ga(III) corroles decrease, while the singlet oxygen quantum yields increase due to an external heavy atom effect. The P(V) and Ga(III) corroles exhibit relatively low in vitro dark cytotoxicity, which was further enhanced upon conjugation to AuNPs. The P(V) complexes and their AuNP conjugates display more favorable PDT activity properties upon illumination with a Thorlabs 625 nm light-emitting diode (288 J cm−2) with phototoxicity indices > 18.5 and 20.8, respectively, for the meso-thienyl-substituted 2b-AuNP and 2c-AuNP conjugates. Optical spectroscopy analyses demonstrate that this can be attributed to there being significantly less aggregation due to the presence of two trans-hydroxy axial ligands.
- Full Text:
- Date Issued: 2021
- Authors: Soy, Rodah C , Babu, Balaji , Mack, John , Nyokong, Tebello
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/185678 , vital:44409 , xlink:href="https://doi.org/10.1016/j.dyepig.2021.109631"
- Description: The synthesis and characterization of series of P(V) and Ga(III) A3 triarylcorrole complexes with 4-methylthiophenyl (2a, 3a), thien-3-yl (2b, 3b) and thien-2-yl (2c, 3c) meso-groups are reported along with the physicochemical and photodynamic activity properties of the dyes and their gold nanoparticle (AuNP) conjugates. The Ga(III) corrole series have lower fluorescence quantum yields and higher singlet oxygen quantum yields than the analogous P(V) complexes. Upon conjugation to AuNPs, the fluorescence quantum yields of the P(V) and Ga(III) corroles decrease, while the singlet oxygen quantum yields increase due to an external heavy atom effect. The P(V) and Ga(III) corroles exhibit relatively low in vitro dark cytotoxicity, which was further enhanced upon conjugation to AuNPs. The P(V) complexes and their AuNP conjugates display more favorable PDT activity properties upon illumination with a Thorlabs 625 nm light-emitting diode (288 J cm−2) with phototoxicity indices > 18.5 and 20.8, respectively, for the meso-thienyl-substituted 2b-AuNP and 2c-AuNP conjugates. Optical spectroscopy analyses demonstrate that this can be attributed to there being significantly less aggregation due to the presence of two trans-hydroxy axial ligands.
- Full Text:
- Date Issued: 2021
The photodynamic activities of the gold nanoparticle conjugates of phosphorus (V) and gallium (III) A3 meso-triarylcorroles
- Soy, Rodah C, Babu, Balaji, Mack, John, Nyokong, Tebello
- Authors: Soy, Rodah C , Babu, Balaji , Mack, John , Nyokong, Tebello
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/184978 , vital:44313 , xlink:href="https://doi.org/10.1016/j.dyepig.2021.109631"
- Description: The synthesis and characterization of series of P(V) and Ga(III) A3 triarylcorrole complexes with 4-methylthiophenyl (2a, 3a), thien-3-yl (2b, 3b) and thien-2-yl (2c, 3c) meso-groups are reported along with the physicochemical and photodynamic activity properties of the dyes and their gold nanoparticle (AuNP) conjugates. The Ga(III) corrole series have lower fluorescence quantum yields and higher singlet oxygen quantum yields than the analogous P(V) complexes. Upon conjugation to AuNPs, the fluorescence quantum yields of the P(V) and Ga(III) corroles decrease, while the singlet oxygen quantum yields increase due to an external heavy atom effect. The P(V) and Ga(III) corroles exhibit relatively low in vitro dark cytotoxicity, which was further enhanced upon conjugation to AuNPs. The P(V) complexes and their AuNP conjugates display more favorable PDT activity properties upon illumination with a Thorlabs 625 nm light-emitting diode (288 J cm−2) with phototoxicity indices > 18.5 and 20.8, respectively, for the meso-thienyl-substituted 2b-AuNP and 2c-AuNP conjugates. Optical spectroscopy analyses demonstrate that this can be attributed to there being significantly less aggregation due to the presence of two trans-hydroxy axial ligands.
- Full Text:
- Date Issued: 2021
- Authors: Soy, Rodah C , Babu, Balaji , Mack, John , Nyokong, Tebello
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/184978 , vital:44313 , xlink:href="https://doi.org/10.1016/j.dyepig.2021.109631"
- Description: The synthesis and characterization of series of P(V) and Ga(III) A3 triarylcorrole complexes with 4-methylthiophenyl (2a, 3a), thien-3-yl (2b, 3b) and thien-2-yl (2c, 3c) meso-groups are reported along with the physicochemical and photodynamic activity properties of the dyes and their gold nanoparticle (AuNP) conjugates. The Ga(III) corrole series have lower fluorescence quantum yields and higher singlet oxygen quantum yields than the analogous P(V) complexes. Upon conjugation to AuNPs, the fluorescence quantum yields of the P(V) and Ga(III) corroles decrease, while the singlet oxygen quantum yields increase due to an external heavy atom effect. The P(V) and Ga(III) corroles exhibit relatively low in vitro dark cytotoxicity, which was further enhanced upon conjugation to AuNPs. The P(V) complexes and their AuNP conjugates display more favorable PDT activity properties upon illumination with a Thorlabs 625 nm light-emitting diode (288 J cm−2) with phototoxicity indices > 18.5 and 20.8, respectively, for the meso-thienyl-substituted 2b-AuNP and 2c-AuNP conjugates. Optical spectroscopy analyses demonstrate that this can be attributed to there being significantly less aggregation due to the presence of two trans-hydroxy axial ligands.
- Full Text:
- Date Issued: 2021