Think Piece. Conceptions of Quality and ‘Learning as Connection’: Teaching for Relevance
- Authors: Lotz-Sisitka, Heila
- Date: 2013
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/387159 , vital:68211 , xlink:href="https://www.ajol.info/index.php/sajee/article/view/122256"
- Description: This think piece captures some of the thinking that emerged in and through the Southern African Development Community (SADC) Regional Environmental Education Programme research programme. This research programme emerged over a five-year period (2008–2012) and involved ten southern African teacher education institutions from eight countries (see ‘Acknowledgements’). The research programme sought to understand what contributions environment and sustainability education could make to debates on educational quality and relevance. Issues of educational quality are high on the national agendas of governments in southern Africa, as it is now well known that providing access to schooling is not a sufficient condition for achieving educational quality. Educational quality is intimately linked to the processes of teaching and learning, but the concept of educational quality is not unproblematic in and of itself. It is, as Noel Gough (2005) noted many years ago, an ‘order word’ that shapes the way people think and practise. Our enquiries during this research programme involved a number of case studies (that were reported on in the Southern African Journal of Environmental Education (SAJEE) in 2008, and are again reported on in this edition of the SAJEE), but the programme also involved theoretical engagement with the concept of educational quality and relevance.
- Full Text:
- Date Issued: 2013
- Authors: Lotz-Sisitka, Heila
- Date: 2013
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/387159 , vital:68211 , xlink:href="https://www.ajol.info/index.php/sajee/article/view/122256"
- Description: This think piece captures some of the thinking that emerged in and through the Southern African Development Community (SADC) Regional Environmental Education Programme research programme. This research programme emerged over a five-year period (2008–2012) and involved ten southern African teacher education institutions from eight countries (see ‘Acknowledgements’). The research programme sought to understand what contributions environment and sustainability education could make to debates on educational quality and relevance. Issues of educational quality are high on the national agendas of governments in southern Africa, as it is now well known that providing access to schooling is not a sufficient condition for achieving educational quality. Educational quality is intimately linked to the processes of teaching and learning, but the concept of educational quality is not unproblematic in and of itself. It is, as Noel Gough (2005) noted many years ago, an ‘order word’ that shapes the way people think and practise. Our enquiries during this research programme involved a number of case studies (that were reported on in the Southern African Journal of Environmental Education (SAJEE) in 2008, and are again reported on in this edition of the SAJEE), but the programme also involved theoretical engagement with the concept of educational quality and relevance.
- Full Text:
- Date Issued: 2013
Bayesian spatio-temporal zero-inflated mixed models for overdispersion on chronic disease mapping
- Osuji, Georgeleen O https://orcid.org/0000-0002-8408-3928
- Authors: Osuji, Georgeleen O https://orcid.org/0000-0002-8408-3928
- Date: 2021-12
- Subjects: Medical mapping , Bayesian statistical decision theory
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10353/23644 , vital:58230
- Description: Background: Life expectancy in most developing countries has remarkably increased and decreased in mortality, but under 5 years old mortality has increased due to HIV and Tuberculosis incidence. Many factors have been established to influence the mortality rate among HIV patients and understanding the factors contribution to the risk of under 5-year-old mortality is important for designing appropriate health interventions. Excess zeros usually occur in such HIV mortality count data. Mixed models consisting of count part and zero part are often used to describe the observed excess zero in the data. Poisson models are popular modeling inference, but Negative-Binomial models are more flexible in analyzing count data and dealing with overdispersion. Method: This research proposed to develop two-part hurdle models in analyzing areal zero count data. A spatial Bayesian lognormal-logit hurdle model (BLLHM) with random effects characterizes and cross-spatial dependencies were introduced. The parameter inferences and predictions were evaluated using the Markov Chain Monte Carlo algorithm. The model proposed was applied to HIV-positive under 5-year-old mortality collected from the Eastern Cape Department of Health. Results: Bayesian lognormal-logit hurdle model is selected as the best model fit. It is observed that the total number of HIV patients not on ART-HIVnotTB (0.000612, p <0.000) was positively and statistically significantly associated with the HIV-positive mortality of under 5 years patients. Both CD4 counts were done on newly diagnosed HIV rate (CD4count) and HIV-positive new patients screened for TB rate (HIVTBrate) were negatively and statistically significantly associated with the HIV-positive mortality of under 5 years patients (-0.6294, p = 0.000 and -0.00056, p = 0.0052). However, the covariate HIV positive Tuberculosis Preventive therapy (TPT) uptake rate (HIVandTB) was not statistically significantly associated with the HIV-positive mortality of under 5 years patients (-0.00155, p = 0.5392). Conclusion: The model is flexible to deal with zero-inflated and over-dispersed count data. There is a need to consider the risk of cause-specific under-5-year-old mortality in terms of spatial effects. , Thesis (PhD) -- Faculty of Science and Agriculture, 2021
- Full Text:
- Date Issued: 2021-12
- Authors: Osuji, Georgeleen O https://orcid.org/0000-0002-8408-3928
- Date: 2021-12
- Subjects: Medical mapping , Bayesian statistical decision theory
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10353/23644 , vital:58230
- Description: Background: Life expectancy in most developing countries has remarkably increased and decreased in mortality, but under 5 years old mortality has increased due to HIV and Tuberculosis incidence. Many factors have been established to influence the mortality rate among HIV patients and understanding the factors contribution to the risk of under 5-year-old mortality is important for designing appropriate health interventions. Excess zeros usually occur in such HIV mortality count data. Mixed models consisting of count part and zero part are often used to describe the observed excess zero in the data. Poisson models are popular modeling inference, but Negative-Binomial models are more flexible in analyzing count data and dealing with overdispersion. Method: This research proposed to develop two-part hurdle models in analyzing areal zero count data. A spatial Bayesian lognormal-logit hurdle model (BLLHM) with random effects characterizes and cross-spatial dependencies were introduced. The parameter inferences and predictions were evaluated using the Markov Chain Monte Carlo algorithm. The model proposed was applied to HIV-positive under 5-year-old mortality collected from the Eastern Cape Department of Health. Results: Bayesian lognormal-logit hurdle model is selected as the best model fit. It is observed that the total number of HIV patients not on ART-HIVnotTB (0.000612, p <0.000) was positively and statistically significantly associated with the HIV-positive mortality of under 5 years patients. Both CD4 counts were done on newly diagnosed HIV rate (CD4count) and HIV-positive new patients screened for TB rate (HIVTBrate) were negatively and statistically significantly associated with the HIV-positive mortality of under 5 years patients (-0.6294, p = 0.000 and -0.00056, p = 0.0052). However, the covariate HIV positive Tuberculosis Preventive therapy (TPT) uptake rate (HIVandTB) was not statistically significantly associated with the HIV-positive mortality of under 5 years patients (-0.00155, p = 0.5392). Conclusion: The model is flexible to deal with zero-inflated and over-dispersed count data. There is a need to consider the risk of cause-specific under-5-year-old mortality in terms of spatial effects. , Thesis (PhD) -- Faculty of Science and Agriculture, 2021
- Full Text:
- Date Issued: 2021-12
Bridging through “women’s work"
- Authors: Magadla, Siphokazi
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/298650 , vital:57724 , xlink:href="https://doi.org/10.1080/14616742.2020.1863158"
- Description: Bodomo’s bridge theory describes and predicts the long-term implications of African migrants’ activities and settlement in China. Drawing on research with African retail traders, university students, and corporate executives in China, I show that the bridge theory illuminates how African women and men rationalize their decisions to migrate to China within the context of the rise of Asia. Drawing on the literature regarding African women and work, I explain that structural economic conditions now force more Africans into economic sectors such as trade work that historically were dominated by African women. I demonstrate that African women’s roles as economic providers for their families and children in other sectors, such as university students and company executives, provide evidence of the continued “matricentric” nature of African households that rely on women’s economic productivity. I also examine the possibilities and limitations of building long-standing networks that shape African migrant settlement in China. I show that the historical theorization that characterizes global mobility as male – particularly regarding Africans – has contributed to the misrecognition of African women’s multiple activities in China.
- Full Text:
- Date Issued: 2021
- Authors: Magadla, Siphokazi
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/298650 , vital:57724 , xlink:href="https://doi.org/10.1080/14616742.2020.1863158"
- Description: Bodomo’s bridge theory describes and predicts the long-term implications of African migrants’ activities and settlement in China. Drawing on research with African retail traders, university students, and corporate executives in China, I show that the bridge theory illuminates how African women and men rationalize their decisions to migrate to China within the context of the rise of Asia. Drawing on the literature regarding African women and work, I explain that structural economic conditions now force more Africans into economic sectors such as trade work that historically were dominated by African women. I demonstrate that African women’s roles as economic providers for their families and children in other sectors, such as university students and company executives, provide evidence of the continued “matricentric” nature of African households that rely on women’s economic productivity. I also examine the possibilities and limitations of building long-standing networks that shape African migrant settlement in China. I show that the historical theorization that characterizes global mobility as male – particularly regarding Africans – has contributed to the misrecognition of African women’s multiple activities in China.
- Full Text:
- Date Issued: 2021
Investigating thermoregulatory responses of rhabdomys pumilio at high wet-bulb temperatures
- Authors: Hartley, Oliver
- Date: 2023-04
- Subjects: Heat stress physiology , Small mammal thermoregulation -- South Africa , Climate change - Wet-bulb temperature
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10948/60873 , vital:68916
- Description: As the Anthropocene continues to be characterised by ever rising temperature highs, increasingly sporadic and extreme climatic events, and their accompanying mass mortality events, climate scientists now warn that the continued climate destabilisation may for the first time in recorded history prevent terrestrial homeothermic endotherms from being able to thermoregulate. Having evolved to maintain body temperatures (Tbs) well above their ambient (Ta) conditions, these endotherms have evolved a suite of adaptations to a colder environment to allow for homeothermic thermoregulation to occur. However, by the same vein, having evolved in a colder climate to stay warm also has led to a reduced capacity to prevent heat stress when temperature conditions are elevated. In absence of behavioural counter measures, the only physiological means available to thermoregulation to prevent such heat stress is that of evaporative water loss (EWL). If still inefficient, the endotherm will risk becoming hyperthermic. Literature has established that excessive heat exposure or reduced evaporative cooling capacities strain or retard thermoregulatory processes. If an endotherm experiences severe heat exposure, the rate at which passive heating is experienced will increase. Should an endotherm be in a humid environment, evaporative cooling efficiency is reduced. As a result, these two abiotic factors are therefore known to contribute towards heat storage, and therefore thermal stress. However, should both factors occur in the same environment, the heat stress effects are compounded, creating an environment dangerous for thermoregulating endotherms. For this reason, authors have emphasised that future wet-bulb (Tw) conditions may pose a penultimate threat to thermoregulating endotherms. Being a measure of coldest temperature attainable as a result of evaporative cooling, Tw has been proposed to represent a lower temperature thermal limit to endothermic thermoregulation. Once reaching a 2°C differential below an endotherms Tb (Tb – Tw = 2˚C), Tw is believed to impede the evaporative cooling process and, consequentially, commit endotherms to becoming hyperthermic. Considering that most mammals defend constant Tbs within the range of predicted Tw maxima increases that future Tw conditions may pose a significant threat to mammalian thermoregulation. However, to date, despite being well supported in the literature, ii empirical investigations into how extreme Tw conditions will affect endothermic thermoregulation are scant. Therefore, understanding of the proposed inhibitory nature of extreme Tw conditions is lacking. Considering that such conditions are to have a profound effect of endothermic survival, this dearth in understanding could prove fatal. As such, this thesis sought to provide evidence on how extreme Tw conditions may affect thermoregulatory processes in homeothermic endotherms. , Thesis (MSc) -- Faculty of Science, School of Environmental Sciences, 2023
- Full Text:
- Date Issued: 2023-04
- Authors: Hartley, Oliver
- Date: 2023-04
- Subjects: Heat stress physiology , Small mammal thermoregulation -- South Africa , Climate change - Wet-bulb temperature
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10948/60873 , vital:68916
- Description: As the Anthropocene continues to be characterised by ever rising temperature highs, increasingly sporadic and extreme climatic events, and their accompanying mass mortality events, climate scientists now warn that the continued climate destabilisation may for the first time in recorded history prevent terrestrial homeothermic endotherms from being able to thermoregulate. Having evolved to maintain body temperatures (Tbs) well above their ambient (Ta) conditions, these endotherms have evolved a suite of adaptations to a colder environment to allow for homeothermic thermoregulation to occur. However, by the same vein, having evolved in a colder climate to stay warm also has led to a reduced capacity to prevent heat stress when temperature conditions are elevated. In absence of behavioural counter measures, the only physiological means available to thermoregulation to prevent such heat stress is that of evaporative water loss (EWL). If still inefficient, the endotherm will risk becoming hyperthermic. Literature has established that excessive heat exposure or reduced evaporative cooling capacities strain or retard thermoregulatory processes. If an endotherm experiences severe heat exposure, the rate at which passive heating is experienced will increase. Should an endotherm be in a humid environment, evaporative cooling efficiency is reduced. As a result, these two abiotic factors are therefore known to contribute towards heat storage, and therefore thermal stress. However, should both factors occur in the same environment, the heat stress effects are compounded, creating an environment dangerous for thermoregulating endotherms. For this reason, authors have emphasised that future wet-bulb (Tw) conditions may pose a penultimate threat to thermoregulating endotherms. Being a measure of coldest temperature attainable as a result of evaporative cooling, Tw has been proposed to represent a lower temperature thermal limit to endothermic thermoregulation. Once reaching a 2°C differential below an endotherms Tb (Tb – Tw = 2˚C), Tw is believed to impede the evaporative cooling process and, consequentially, commit endotherms to becoming hyperthermic. Considering that most mammals defend constant Tbs within the range of predicted Tw maxima increases that future Tw conditions may pose a significant threat to mammalian thermoregulation. However, to date, despite being well supported in the literature, ii empirical investigations into how extreme Tw conditions will affect endothermic thermoregulation are scant. Therefore, understanding of the proposed inhibitory nature of extreme Tw conditions is lacking. Considering that such conditions are to have a profound effect of endothermic survival, this dearth in understanding could prove fatal. As such, this thesis sought to provide evidence on how extreme Tw conditions may affect thermoregulatory processes in homeothermic endotherms. , Thesis (MSc) -- Faculty of Science, School of Environmental Sciences, 2023
- Full Text:
- Date Issued: 2023-04
A spatial assessment of riparian vegetation density and implications for streambank erosion in relation to land tenure in the Mgwalana Catchment, Eastern Cape Province, South Africa
- Authors: Maxama, Asakhile
- Date: 2021-12
- Subjects: Port Elizabeth (South Africa) , Eastern Cape (South Africa) , South Africa
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10948/53864 , vital:46026
- Description: Riparian vegetation provides an array of various ecosystem functions and has significantly shaped the conditions of catchments. It has strong controls on fluvial geomorphology and erosion processes. The Mgwalana catchment has been intensively studied over the years and the current environmental condition of the study has been linked to land use history. The catchment has been subjected to land use/cover changes (LUCC) over the years. However, spatial variations in riparian vegetation, their implications for stream bank stability and the contribution of land tenure systems to stream channel degradation are poorly understood. The study sought to assess the implications of the spatial variations in riparian vegetation density for stream bank erosion in relation to land tenure on a catchment scale. Land tenure units comprising the catchment of study are traditional and betterment villages (communal lands), and former white commercial farms. A three-pronged approach using GIS and remote sensing, field investigations and laboratory procedures for soil analysis was employed in this study. Variations of riparian vegetation density in the catchment were mapped using ArcGIS for the two land tenure units to assess the spatial variations of riparian density along stream reaches and to determine the spatial relationship between land tenure units and riparian vegetation diminution. Other mapped shape files include sediment accumulation zones to analyse the spatial relationship between riparian vegetation density and sediment sinks. LUCC classification and analysis of the Normalized Difference Vegetation Index (NDVI) were carried out in IDRISI Selva, using Landsat 8 TM imagery of 2018 to represent the current spatial riparian vegetation variations in the catchment. Field investigations were conducted to determine the coupling among hillslope gully erosion, riparian vegetation density and sink areas; and to assess physical characteristics of soil. This would permit an assessment of the implications of riparian vegetation for stream bank erosion and sediment accumulation within the tenure units. Soil samples were taken from scantily and densely vegetated stream reaches, as well as measurements of channel widths and depths. Analyses of soil physical properties viz; grain size distribution, bulk density, soil texture and aggregate stability were done. Results demonstrated that a sparse riparian vegetation distribution was consistent with the communal villages, confined to the upper catchment area. Dense riparian vegetation distribution was consistent with former commercial farms in the lower catchment area. , Thesis (MSc) -- Faculty of Science, School of Environmental Sciences, 2021
- Full Text:
- Date Issued: 2021-12
- Authors: Maxama, Asakhile
- Date: 2021-12
- Subjects: Port Elizabeth (South Africa) , Eastern Cape (South Africa) , South Africa
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10948/53864 , vital:46026
- Description: Riparian vegetation provides an array of various ecosystem functions and has significantly shaped the conditions of catchments. It has strong controls on fluvial geomorphology and erosion processes. The Mgwalana catchment has been intensively studied over the years and the current environmental condition of the study has been linked to land use history. The catchment has been subjected to land use/cover changes (LUCC) over the years. However, spatial variations in riparian vegetation, their implications for stream bank stability and the contribution of land tenure systems to stream channel degradation are poorly understood. The study sought to assess the implications of the spatial variations in riparian vegetation density for stream bank erosion in relation to land tenure on a catchment scale. Land tenure units comprising the catchment of study are traditional and betterment villages (communal lands), and former white commercial farms. A three-pronged approach using GIS and remote sensing, field investigations and laboratory procedures for soil analysis was employed in this study. Variations of riparian vegetation density in the catchment were mapped using ArcGIS for the two land tenure units to assess the spatial variations of riparian density along stream reaches and to determine the spatial relationship between land tenure units and riparian vegetation diminution. Other mapped shape files include sediment accumulation zones to analyse the spatial relationship between riparian vegetation density and sediment sinks. LUCC classification and analysis of the Normalized Difference Vegetation Index (NDVI) were carried out in IDRISI Selva, using Landsat 8 TM imagery of 2018 to represent the current spatial riparian vegetation variations in the catchment. Field investigations were conducted to determine the coupling among hillslope gully erosion, riparian vegetation density and sink areas; and to assess physical characteristics of soil. This would permit an assessment of the implications of riparian vegetation for stream bank erosion and sediment accumulation within the tenure units. Soil samples were taken from scantily and densely vegetated stream reaches, as well as measurements of channel widths and depths. Analyses of soil physical properties viz; grain size distribution, bulk density, soil texture and aggregate stability were done. Results demonstrated that a sparse riparian vegetation distribution was consistent with the communal villages, confined to the upper catchment area. Dense riparian vegetation distribution was consistent with former commercial farms in the lower catchment area. , Thesis (MSc) -- Faculty of Science, School of Environmental Sciences, 2021
- Full Text:
- Date Issued: 2021-12
Rethinking the informal settlements upgrading programmes in the free state province, South Africa: a transformative and multi-faceted model
- Authors: Dintsi, Sive
- Date: 2022-04
- Subjects: Human settlements -- Free State , Squatter settlements
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10948/58352 , vital:59002
- Description: This thesis intended to reveal the factors that contributed to the formulation of the informal settlements upgrading programmes in the Free State, South Africa, from an institutional perspective; subsequently to conceptualise a transformative and multi-faceted model for the development and management of human settlements. The mixed methods exploratory research design has been applied in this study. This research design has allowed for the implementation of research methods including the qualitative inductive content analysis method, the case study method, and the semi-structured survey questionnaire method. The data collection methods used comprised both primary and secondary data. Primary data involved online surveys and field observations. Secondary data comprised of an inductive analysis of written sources. The main findings of the study were as follows. First, the policy design and implementation processes have been misaligned. Second, there has been inadequate stakeholder engagements. Third, the government has not prioritised the employment of specialists in the field of housing and human settlements. Fourth, corruption has caused the state to fail to provide adequate housing for all. Fifth, municipalities are unable to identify and define existing informal settlements. Lastly, illegal immigration is causing a rapid increase in the number of informal settlements. This thesis proffered key recommendations based on the conclusions drawn from these findings. First, there must be an implementation of an integrated model for the preparation of upgrading policy. Second, communication technology education for officials of the state must be enhanced. Third, the government must prioritise the employment of experts in upgrading work. Fourth, the upgrading policy must reflect the paradigm shift from housing to human settlements. Fifth, municipalities need to be systematically transformed and improved for their functions on upgrading. Finally, illegal immigration must be firmly monitored while legal immigration is discouraged. To this end, this thesis has presented a strong viewpoint that limits the influx of immigrants into unproclaimed urban land that leads to the growth of informal settlements. The study has also strongly advocated for the legal spatial placement of South African citizens and legal immigrants on strategically and socio-economically viable land, where it is suitably available and owned by the state. Housing in the thesis has been viewed as one of the essential instruments that must inevitably emerge as a prospect towards xiv effectively unlocking improved living conditions in informal settlements; rather than housing being perceived as human settlements. , Thesis (MA) -- Faculty of Science, School of Environmental Sciences, 2022
- Full Text:
- Date Issued: 2022-04
- Authors: Dintsi, Sive
- Date: 2022-04
- Subjects: Human settlements -- Free State , Squatter settlements
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10948/58352 , vital:59002
- Description: This thesis intended to reveal the factors that contributed to the formulation of the informal settlements upgrading programmes in the Free State, South Africa, from an institutional perspective; subsequently to conceptualise a transformative and multi-faceted model for the development and management of human settlements. The mixed methods exploratory research design has been applied in this study. This research design has allowed for the implementation of research methods including the qualitative inductive content analysis method, the case study method, and the semi-structured survey questionnaire method. The data collection methods used comprised both primary and secondary data. Primary data involved online surveys and field observations. Secondary data comprised of an inductive analysis of written sources. The main findings of the study were as follows. First, the policy design and implementation processes have been misaligned. Second, there has been inadequate stakeholder engagements. Third, the government has not prioritised the employment of specialists in the field of housing and human settlements. Fourth, corruption has caused the state to fail to provide adequate housing for all. Fifth, municipalities are unable to identify and define existing informal settlements. Lastly, illegal immigration is causing a rapid increase in the number of informal settlements. This thesis proffered key recommendations based on the conclusions drawn from these findings. First, there must be an implementation of an integrated model for the preparation of upgrading policy. Second, communication technology education for officials of the state must be enhanced. Third, the government must prioritise the employment of experts in upgrading work. Fourth, the upgrading policy must reflect the paradigm shift from housing to human settlements. Fifth, municipalities need to be systematically transformed and improved for their functions on upgrading. Finally, illegal immigration must be firmly monitored while legal immigration is discouraged. To this end, this thesis has presented a strong viewpoint that limits the influx of immigrants into unproclaimed urban land that leads to the growth of informal settlements. The study has also strongly advocated for the legal spatial placement of South African citizens and legal immigrants on strategically and socio-economically viable land, where it is suitably available and owned by the state. Housing in the thesis has been viewed as one of the essential instruments that must inevitably emerge as a prospect towards xiv effectively unlocking improved living conditions in informal settlements; rather than housing being perceived as human settlements. , Thesis (MA) -- Faculty of Science, School of Environmental Sciences, 2022
- Full Text:
- Date Issued: 2022-04
The synthesis, fluorescence behaviour and singlet oxygen studies of new water-soluble cationic gallium (III) phthalocyanines
- Durmus, Mahmut, Nyokong, Tebello
- Authors: Durmus, Mahmut , Nyokong, Tebello
- Date: 2007
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/280207 , vital:55586 , xlink:href="https://doi.org/10.1016/j.inoche.2006.11.012"
- Description: The preparation of cationic water-soluble gallium phthalocyanine derivatives are described for the first time. Peripheral and non-peripheral 3-hydroxypyridine tetrasubstituted gallium(III)phthalocyanines (5a, 6a) and their quaternarized derivatives (5b and 6b) have been synthesized and characterized by elemental analysis, IR, 1H NMR spectroscopy, electronic spectroscopy and mass spectra. The quaternarized compounds (5b and 6b) are soluble in water and not aggregated (in water and in organic solvents) within a wide concentration range. General trends are described for singlet oxygen quantum yields, fluorescence quantum yields and fluorescence lifetimes of these compounds. These complexes showed better singlet oxygen quantum yields in water than the related quarternarized porphyrazine complexes.
- Full Text:
- Date Issued: 2007
- Authors: Durmus, Mahmut , Nyokong, Tebello
- Date: 2007
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/280207 , vital:55586 , xlink:href="https://doi.org/10.1016/j.inoche.2006.11.012"
- Description: The preparation of cationic water-soluble gallium phthalocyanine derivatives are described for the first time. Peripheral and non-peripheral 3-hydroxypyridine tetrasubstituted gallium(III)phthalocyanines (5a, 6a) and their quaternarized derivatives (5b and 6b) have been synthesized and characterized by elemental analysis, IR, 1H NMR spectroscopy, electronic spectroscopy and mass spectra. The quaternarized compounds (5b and 6b) are soluble in water and not aggregated (in water and in organic solvents) within a wide concentration range. General trends are described for singlet oxygen quantum yields, fluorescence quantum yields and fluorescence lifetimes of these compounds. These complexes showed better singlet oxygen quantum yields in water than the related quarternarized porphyrazine complexes.
- Full Text:
- Date Issued: 2007
An octabrominated Sn (iv) tetraisopropylporphyrin as a photosensitizer dye for singlet oxygen biomedical applications
- Babu, Balaji, Mack, John, Nyokong, Tebello
- Authors: Babu, Balaji , Mack, John , Nyokong, Tebello
- Date: 2020
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/186679 , vital:44524 , xlink:href="https://doi.org/10.1039/D0DT01915A"
- Description: Two novel Sn(IV) tetraisopropylphenylporphyrins have been synthesized to explore the effect of octabromination at the β-pyrrole positions on their photophysical properties and photodynamic activity. The lower energy Q band of an octabrominated complex lies at 675 nm well within the therapeutic window. The octabrominated dye has a relatively high singlet oxygen quantum yield of 0.78 in DMF and exhibits favorable photodynamic activity against MCF-7 cells with an IC50 value of 10.7 μM and a 5.74 log reduction value (5 μM) towards S. aureus under illumination at 660 nm for 60 min with a Thorlabs M660L3 LED (280 mW cm−2).
- Full Text:
- Date Issued: 2020
- Authors: Babu, Balaji , Mack, John , Nyokong, Tebello
- Date: 2020
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/186679 , vital:44524 , xlink:href="https://doi.org/10.1039/D0DT01915A"
- Description: Two novel Sn(IV) tetraisopropylphenylporphyrins have been synthesized to explore the effect of octabromination at the β-pyrrole positions on their photophysical properties and photodynamic activity. The lower energy Q band of an octabrominated complex lies at 675 nm well within the therapeutic window. The octabrominated dye has a relatively high singlet oxygen quantum yield of 0.78 in DMF and exhibits favorable photodynamic activity against MCF-7 cells with an IC50 value of 10.7 μM and a 5.74 log reduction value (5 μM) towards S. aureus under illumination at 660 nm for 60 min with a Thorlabs M660L3 LED (280 mW cm−2).
- Full Text:
- Date Issued: 2020
Fabrication of asymmetrical morpholine phthalocyanines conjugated chitosan-polyacrylonitrile nanofibers for improved photodynamic antimicrobial chemotherapy activity
- Sindelo, Azole, Mafukidze, Donovan M, Nyokong, Tebello
- Authors: Sindelo, Azole , Mafukidze, Donovan M , Nyokong, Tebello
- Date: 2022
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/229873 , vital:49719 , xlink:href="https://doi.org/10.1016/j.pdpdt.2022.102760"
- Description: The work is based on the synthesis and photodynamic antimicrobial chemotherapy (PACT) activities of neutral (1 and 2) and cationic (1Q and 2Q) morpholine substituted phthalocyanines. For applicability, these complexes were covalently linked to modified polyacrylonitrile (PAN) to form 1-PAN, 2-PAN, 1Q-PAN, and 2Q-PAN, respectively. Chitosan was conjugated to PAN (to form PAN-CS) which was then linked to the Pcs to form PAN-CS-1, PAN-CS-2, PAN-CS-1Q, and PAN-CS-2Q, respectively. Singlet oxygen quantum yields improved following the inclusion of chitosan. The PACT activities of the complexes alone and when anchored to both PAN and PAN-CS was evaluated against bacteria: S. aureus, E. coli and fungi C. albicans. Cationic phthalocyanine showed high efficacy values of >7 log reduction value for all microorganisms. These results translated into excellent bacterial colony reduction of >90% against both S. aureus and C. albicans after 1 h of photoirradiation on PAN-CS support.
- Full Text:
- Date Issued: 2022
- Authors: Sindelo, Azole , Mafukidze, Donovan M , Nyokong, Tebello
- Date: 2022
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/229873 , vital:49719 , xlink:href="https://doi.org/10.1016/j.pdpdt.2022.102760"
- Description: The work is based on the synthesis and photodynamic antimicrobial chemotherapy (PACT) activities of neutral (1 and 2) and cationic (1Q and 2Q) morpholine substituted phthalocyanines. For applicability, these complexes were covalently linked to modified polyacrylonitrile (PAN) to form 1-PAN, 2-PAN, 1Q-PAN, and 2Q-PAN, respectively. Chitosan was conjugated to PAN (to form PAN-CS) which was then linked to the Pcs to form PAN-CS-1, PAN-CS-2, PAN-CS-1Q, and PAN-CS-2Q, respectively. Singlet oxygen quantum yields improved following the inclusion of chitosan. The PACT activities of the complexes alone and when anchored to both PAN and PAN-CS was evaluated against bacteria: S. aureus, E. coli and fungi C. albicans. Cationic phthalocyanine showed high efficacy values of >7 log reduction value for all microorganisms. These results translated into excellent bacterial colony reduction of >90% against both S. aureus and C. albicans after 1 h of photoirradiation on PAN-CS support.
- Full Text:
- Date Issued: 2022
Photochemistry, photophysics and nonlinear optical parameters of phenoxy and tert-butylphenoxy substituted indium (III) phthalocyanines
- Chauke, Vongani, Durmus, Mahmut, Nyokong, Tebello
- Authors: Chauke, Vongani , Durmus, Mahmut , Nyokong, Tebello
- Date: 2007
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/268823 , vital:54235 , xlink:href="https://doi.org/10.1016/j.jphotochem.2007.05.022"
- Description: This work hereby presents the syntheses, photochemistry and photophysics of octaphenoxy ((Cl)InOPPc) and octakis(4-tert-butylphenoxy)chloroindium ((Cl)InOTBPPc) phthalocyanines. Calculated nonlinear parameters of these complexes are compared with those of the corresponding GaPc derivatives and tetrasubstituted GaPc and InPc complexes. Fluorescence quantum yields do not vary much between (Cl)InOPPc and (Cl)InOTBPPc complexes in different solvents. High quantum yields of triplet state (ΦT ranging from 0.70 to 0.91 in dimethysulphoxide, DMSO) and singlet oxygen generation (ΦΔ, ranging from 0.61 to 0.79 in DMSO) were obtained. Short triplet lifetimes 50–60 μs were obtained in DMSO). The optical limiting threshold intensity (Ilim) for the InPc derivatives were calculated and compared with those of corresponding tetrasubstituted InPc and GaPc complexes. The latter were found to be better optical limiters.
- Full Text:
- Date Issued: 2007
- Authors: Chauke, Vongani , Durmus, Mahmut , Nyokong, Tebello
- Date: 2007
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/268823 , vital:54235 , xlink:href="https://doi.org/10.1016/j.jphotochem.2007.05.022"
- Description: This work hereby presents the syntheses, photochemistry and photophysics of octaphenoxy ((Cl)InOPPc) and octakis(4-tert-butylphenoxy)chloroindium ((Cl)InOTBPPc) phthalocyanines. Calculated nonlinear parameters of these complexes are compared with those of the corresponding GaPc derivatives and tetrasubstituted GaPc and InPc complexes. Fluorescence quantum yields do not vary much between (Cl)InOPPc and (Cl)InOTBPPc complexes in different solvents. High quantum yields of triplet state (ΦT ranging from 0.70 to 0.91 in dimethysulphoxide, DMSO) and singlet oxygen generation (ΦΔ, ranging from 0.61 to 0.79 in DMSO) were obtained. Short triplet lifetimes 50–60 μs were obtained in DMSO). The optical limiting threshold intensity (Ilim) for the InPc derivatives were calculated and compared with those of corresponding tetrasubstituted InPc and GaPc complexes. The latter were found to be better optical limiters.
- Full Text:
- Date Issued: 2007
Synthesis of peptidomimetic compounds as HIV-1 protease inhibitors
- Authors: Kayembe, Jean-Pierre
- Date: 2020
- Subjects: Protease inhibitors , HIV (Viruses) , HIV infections Treatment , Peptidomimetics
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/124397 , vital:35604 , DOI https://dx.doi.org/10.21504/10962/124397
- Description: This research project has involved the design, synthesis and evaluation of novel peptidomimetics compounds as HIV-1 protease inhibitors. Here is presented one-step, two-step and three-step syntheses and the in vitro bio-assay studies of a series of fully characterized peptidomimetics as HIV-1 protease inhibitors candidate using the shortest and most cost effective synthetic routes. The first series of compounds were accessed via a synthetic elaboration of Morita-Baylis-Hillman adducts by a Michael addition with benzylamine, proline or glycine esters to afford a series of β-amino-β’-hydroxycarboxylate esters in moderate to good yields. Base-catalyzed cyclization of non-benzylated aza-Michael adducts afforded a series of coumarin-3-hydroxy-2-methylenepropanoate esters in moderate yields. The uncatalyzed direct amidation of diethyl tartrate/tartaric acid and tartaric acid osazone with selected amines/amino acids afforded a series of C2-symmetrical and unsymmetrical 1,2-dihydroxycarboxylates in moderate to very high yields. All the synthesized compounds were fully characterized using spectroscopic techniques. These conjugates, designed as potential HIV-1 inhibitors, were tested against the HIV-1 protease enzyme. A number of these ligands have exhibited inhibition levels and IC50 values comparable to ritonavir, permitting, therefore, their identification as lead compounds for the development of novel inhibitors. , Thesis (PhD) -- Faculty of Science, Chemistry, 2020
- Full Text: false
- Date Issued: 2020
- Authors: Kayembe, Jean-Pierre
- Date: 2020
- Subjects: Protease inhibitors , HIV (Viruses) , HIV infections Treatment , Peptidomimetics
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/124397 , vital:35604 , DOI https://dx.doi.org/10.21504/10962/124397
- Description: This research project has involved the design, synthesis and evaluation of novel peptidomimetics compounds as HIV-1 protease inhibitors. Here is presented one-step, two-step and three-step syntheses and the in vitro bio-assay studies of a series of fully characterized peptidomimetics as HIV-1 protease inhibitors candidate using the shortest and most cost effective synthetic routes. The first series of compounds were accessed via a synthetic elaboration of Morita-Baylis-Hillman adducts by a Michael addition with benzylamine, proline or glycine esters to afford a series of β-amino-β’-hydroxycarboxylate esters in moderate to good yields. Base-catalyzed cyclization of non-benzylated aza-Michael adducts afforded a series of coumarin-3-hydroxy-2-methylenepropanoate esters in moderate yields. The uncatalyzed direct amidation of diethyl tartrate/tartaric acid and tartaric acid osazone with selected amines/amino acids afforded a series of C2-symmetrical and unsymmetrical 1,2-dihydroxycarboxylates in moderate to very high yields. All the synthesized compounds were fully characterized using spectroscopic techniques. These conjugates, designed as potential HIV-1 inhibitors, were tested against the HIV-1 protease enzyme. A number of these ligands have exhibited inhibition levels and IC50 values comparable to ritonavir, permitting, therefore, their identification as lead compounds for the development of novel inhibitors. , Thesis (PhD) -- Faculty of Science, Chemistry, 2020
- Full Text: false
- Date Issued: 2020
Agricultural entrepreneurship development as strategy for economic empowerment: The case of small-scale farmers in Eastern Cape Province of South Africa
- Authors: Akinwale, Olusola Mokayode
- Date: 2020-11
- Subjects: Sustainable development -- South Africa -- Eastern Cape , South Africa -- Economic conditions
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10353/20241 , vital:45637
- Description: This study emanated from the struggle for economic empowerment among small-scale farmers in South African. The study advocates for the establishment of a viable environment where agricultural entrepreneurship can thrive. While the South African Nation Development Plan (NDP) proposed to create one million jobs through agricultural sector by 2030, the majority of small-scale farmers in South Africa are struggling to grow beyond the level of subsistence farming, and the youths appear not to be interested in the farming. It is therefore become necessary to conduct this current study that is exploratory in nature; it explored several factors and barriers to agricultural entrepreneurship development, as well as factors that can contribute to the development of prosperous and sustainable agricultural entrepreneurship among small-scale farmers in South African. The study was conducted in two district municipalities of Eastern Cape Province of South Africa – OR Tambo and Chris Hani. Both quantitative and qualitative research methods were used to make findings. Findings from the study shows that economic empowerment can be achieved through agricultural entrepreneurship development by giving adequate attention to specific factors like individuals’ attitude, production skills, access to market and marketing skills, management skills. Empirically, basic components like personal interests, adequate training and background, efficient extension service, famers’ network and communication, specific goal-oriented, understanding market, farmers’ collaboration, and access to sufficient funding are few of the factors that will make the small-scale farmers grow to the level of commercial farming. The study concluded that prerequisite to developing a sustainable agricultural entrepreneurship climate among small-scale farmers in South African is the combination of basic components aforementioned. Suggestions were made for strong collaboration between government and private sectors to provide development assistance for small-scale farmers as they struggles to develop their small-scale farming to sustainable entrepreneurship level. , Thesis (DPhil) -- Faculty of Management and Commerce, 2020
- Full Text:
- Date Issued: 2020-11
- Authors: Akinwale, Olusola Mokayode
- Date: 2020-11
- Subjects: Sustainable development -- South Africa -- Eastern Cape , South Africa -- Economic conditions
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10353/20241 , vital:45637
- Description: This study emanated from the struggle for economic empowerment among small-scale farmers in South African. The study advocates for the establishment of a viable environment where agricultural entrepreneurship can thrive. While the South African Nation Development Plan (NDP) proposed to create one million jobs through agricultural sector by 2030, the majority of small-scale farmers in South Africa are struggling to grow beyond the level of subsistence farming, and the youths appear not to be interested in the farming. It is therefore become necessary to conduct this current study that is exploratory in nature; it explored several factors and barriers to agricultural entrepreneurship development, as well as factors that can contribute to the development of prosperous and sustainable agricultural entrepreneurship among small-scale farmers in South African. The study was conducted in two district municipalities of Eastern Cape Province of South Africa – OR Tambo and Chris Hani. Both quantitative and qualitative research methods were used to make findings. Findings from the study shows that economic empowerment can be achieved through agricultural entrepreneurship development by giving adequate attention to specific factors like individuals’ attitude, production skills, access to market and marketing skills, management skills. Empirically, basic components like personal interests, adequate training and background, efficient extension service, famers’ network and communication, specific goal-oriented, understanding market, farmers’ collaboration, and access to sufficient funding are few of the factors that will make the small-scale farmers grow to the level of commercial farming. The study concluded that prerequisite to developing a sustainable agricultural entrepreneurship climate among small-scale farmers in South African is the combination of basic components aforementioned. Suggestions were made for strong collaboration between government and private sectors to provide development assistance for small-scale farmers as they struggles to develop their small-scale farming to sustainable entrepreneurship level. , Thesis (DPhil) -- Faculty of Management and Commerce, 2020
- Full Text:
- Date Issued: 2020-11
The implementation of tourism curriculum in secondary schools in Fort Beaufort Education District, Eastern Cape Province: implications for sustainable tourism
- Mbilini-Kuze, Bukiwe Nomonde Constance
- Authors: Mbilini-Kuze, Bukiwe Nomonde Constance
- Date: 2021-04
- Subjects: Education, Secondary -- Curricula , Curriculum planning
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10353/24728 , vital:63536
- Description: This study examined the implementation of Tourism curriculum in Secondary Schools in Fort Beaufort Education District in the Eastern Cape. The study arose from a concern that despite the Government of the Eastern Cape organizing workshops to facilitate the implementation of Tourism curriculum for secondary school teachers, research has shown that teachers have not improved their classroom practice. It discussed the concept of Tourism curriculum implementation and highlighted problems militating against curriculum implementation at secondary school level. The researcher adopted the mixed method methodology which is embedded in the post-positivist research paradigm. The post-positivist research paradigm explains the way things are and views objectivity as an ideal that can never be achieved, however research should be conducted with greater awareness of subjectivity. By combining qualitative and quantitative methodologies, it assisted the researcher to strike a balance and avoid being subjective on issues of teacher capacity, teaching strategies and assessment, availability and use of resources and support and monitoring. The research methods used in this study include questionnaires, interviews, document analysis and observations. The findings of the study showed that there are limitations in the implementation of Tourism curriculum because of lack of capacity of School management Teams and teachers who are implementing NCS Tourism. Although the teaching strategies and assessment are stipulated in the curriculum document teachers are not using appropriate methods and assessment. Moreover, there are crucial resources and facilities provided by SMTs and the Department of Education to implement Tourism curriculum, inadequate compared to those provided for other subjects. Moreover there are limitations in terms of support (including training) and monitoring systems which are in place to enable the implementation of NCS Tourism. Possible areas for future research were highlighted and recommendations were made, for example the researcher recommends teachers to be trained adequately in order to effectively implement the Tourism curriculum. Teachers should be encouraged to use new learner-centred teaching strategies and resources should be provided in all secondary schools through the combined effort of the government, Fort Beaufort Education district and the School Management Teams (SMTs). Support and monitoring systems should be in place for proper implementation of Tourism curriculum. Tourism industries should contribute through provision of instructional materials and teachers as implementers of the curriculum should be involved in decision-making and curriculum planning. The government should employ enough teachers qualified to teach Tourism. On the other hand subject advisors should be adequately trained to enable them to provide relevant support to teachers in Fort Beaufort secondary schools. All stakeholders should be involved in fostering skills and capacities at local level to develop sustainable Tourism and local development in an integrated way. The study identified a possible an alternative model for the implementation of Tourism curriculum. , Thesis (PhD) -- Faculty of Education, 2012
- Full Text:
- Date Issued: 2021-04
- Authors: Mbilini-Kuze, Bukiwe Nomonde Constance
- Date: 2021-04
- Subjects: Education, Secondary -- Curricula , Curriculum planning
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10353/24728 , vital:63536
- Description: This study examined the implementation of Tourism curriculum in Secondary Schools in Fort Beaufort Education District in the Eastern Cape. The study arose from a concern that despite the Government of the Eastern Cape organizing workshops to facilitate the implementation of Tourism curriculum for secondary school teachers, research has shown that teachers have not improved their classroom practice. It discussed the concept of Tourism curriculum implementation and highlighted problems militating against curriculum implementation at secondary school level. The researcher adopted the mixed method methodology which is embedded in the post-positivist research paradigm. The post-positivist research paradigm explains the way things are and views objectivity as an ideal that can never be achieved, however research should be conducted with greater awareness of subjectivity. By combining qualitative and quantitative methodologies, it assisted the researcher to strike a balance and avoid being subjective on issues of teacher capacity, teaching strategies and assessment, availability and use of resources and support and monitoring. The research methods used in this study include questionnaires, interviews, document analysis and observations. The findings of the study showed that there are limitations in the implementation of Tourism curriculum because of lack of capacity of School management Teams and teachers who are implementing NCS Tourism. Although the teaching strategies and assessment are stipulated in the curriculum document teachers are not using appropriate methods and assessment. Moreover, there are crucial resources and facilities provided by SMTs and the Department of Education to implement Tourism curriculum, inadequate compared to those provided for other subjects. Moreover there are limitations in terms of support (including training) and monitoring systems which are in place to enable the implementation of NCS Tourism. Possible areas for future research were highlighted and recommendations were made, for example the researcher recommends teachers to be trained adequately in order to effectively implement the Tourism curriculum. Teachers should be encouraged to use new learner-centred teaching strategies and resources should be provided in all secondary schools through the combined effort of the government, Fort Beaufort Education district and the School Management Teams (SMTs). Support and monitoring systems should be in place for proper implementation of Tourism curriculum. Tourism industries should contribute through provision of instructional materials and teachers as implementers of the curriculum should be involved in decision-making and curriculum planning. The government should employ enough teachers qualified to teach Tourism. On the other hand subject advisors should be adequately trained to enable them to provide relevant support to teachers in Fort Beaufort secondary schools. All stakeholders should be involved in fostering skills and capacities at local level to develop sustainable Tourism and local development in an integrated way. The study identified a possible an alternative model for the implementation of Tourism curriculum. , Thesis (PhD) -- Faculty of Education, 2012
- Full Text:
- Date Issued: 2021-04
Synthesis and solvent effects on the electronic absorption and fluorescence spectral properties of substituted zinc phthalocyanines
- Durmus, Mahmut, Nyokong, Tebello
- Authors: Durmus, Mahmut , Nyokong, Tebello
- Date: 2007
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/283140 , vital:55914 , xlink:href="https://doi.org/10.1016/j.poly.2007.01.018"
- Description: The synthesis and spectroscopic properties of the following tetra- and octa-substituted aryloxy zinc(II) phthalocyanines are reported for the first time: 1,(4)-(tetrabenzyloxyphenoxyphthalocyaninato) zinc(II) (7); 2,(3)-(tetrabenzyloxyphenoxyphthalocyaninato) zinc(II) (8); 2,3-(octabenzyloxyphenoxyphthalocyaninato) zinc(II) (9). The new compounds have been characterized by elemental analysis, IR, 1H NMR spectroscopy and electronic spectroscopy. Spectroscopic properties of these compounds were investigated in different solvents. Protonation of non-peripherally substituted complex 7 resulted in the splitting and red-shifting of the Q-band. The peripherally substituted derivatives 8 and 9, did not show the split in the Q-band. Fluorescence spectra of the derivatives show Stokes shifts typical of MPc complexes.
- Full Text:
- Date Issued: 2007
- Authors: Durmus, Mahmut , Nyokong, Tebello
- Date: 2007
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/283140 , vital:55914 , xlink:href="https://doi.org/10.1016/j.poly.2007.01.018"
- Description: The synthesis and spectroscopic properties of the following tetra- and octa-substituted aryloxy zinc(II) phthalocyanines are reported for the first time: 1,(4)-(tetrabenzyloxyphenoxyphthalocyaninato) zinc(II) (7); 2,(3)-(tetrabenzyloxyphenoxyphthalocyaninato) zinc(II) (8); 2,3-(octabenzyloxyphenoxyphthalocyaninato) zinc(II) (9). The new compounds have been characterized by elemental analysis, IR, 1H NMR spectroscopy and electronic spectroscopy. Spectroscopic properties of these compounds were investigated in different solvents. Protonation of non-peripherally substituted complex 7 resulted in the splitting and red-shifting of the Q-band. The peripherally substituted derivatives 8 and 9, did not show the split in the Q-band. Fluorescence spectra of the derivatives show Stokes shifts typical of MPc complexes.
- Full Text:
- Date Issued: 2007
Assessing the implementation of environmental education school policy in Buffalo City Metro Education District South Africa
- Authors: Damoah, Benjamin
- Date: 2021-12
- Subjects: Environmental education , Environmental policy -- South Africa , Education and state -- South Africa
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10353/21602 , vital:51703
- Description: Environmental Education (EE) is essential for addressing environmental challenges.The advantages of EE are undeniable; it might be used to address specific environmental concerns and their implications, as well as to modify behaviours that lead to environmental catastrophes.EE strengthens people's resilience to climaterelated hazards. Global environmental issues have heightened interest in educational policy outcomes and their implications for economic growth and social citizenship. It is worth noting that an effective EE policy has a significant influence on the development of learners' environmental literacy. This study assessed the implementation of environmental education school policy in the Buffalo City Metro Education District, South Africa. This study adopted the pragmatism paradigm of Mixed Method Research(MMR). Concurrent triangulation, which is a design that employs a single data collection technique in which quantitative and qualitative data gathering and analysis are carried out independently yet concurrently, was used for this study. The target population of this study involved 60,412 teachers, 1,770,289 learners in 5205 public schools, and 1 Pro-EE civil society organisation in the Eastern Cape province. This was narrowed down to over 268 public and independent schools, teachers, and principals within the enclave of the Buffalo Metropolitan education district. The study adopted stratified purposeful and simple random probability sampling. In this technique, the sampling frame of the study was divided into strata or groups (principals, teachers, learners, and CSOs) and a sample was purposefully selected from each stratum (Migiro & Magangi, 2011). The stratified purposeful random sampling techniques draw data from 10 principals, 175 teachers, 1500 learners, and 1 CSO. Structured questionnaire; Implementation of EE Policy Questionnaire (IEEPQ) whose reliability co-efficient value using Cronbach Alpha was 0.74, semi-structured interview and documents were the instruments used to collect data for this study. The data were analysed using descriptive statistics of percentage, mean, and standard deviation for the quantitative data while the thematic approach of sorting, coding, transcribing, and categorization was used for the qualitative data. The study revealed the following. When asked whether teachers had studied environmental education in tertiary institutions as part of their professional training, the majority of the teachers'respondents, 108, representing 61.7percent, disagreed with this view. On the flip side, a handful of teachers 67, (38.3percent) agreed with the view of having had some sort of EE knowledge during their professional training as teachers. With regards to the view that learners learn environmental issues through other subjects, most of the learner respondents, 1316 representing 87.7percent, agreed with this view. On the contrary, a minority of the respondents 184 (12,3percent) had a dissenting opinion. This indicates that most learners in school learn about environmental concerns through other traditional subjects. The study established that EE content is manifest in teachers' and learners' textbooks, teaching methods, and co-curricular activities. However, the study identified lapses in how teachers and learners integrate EE into their day-to-day practices. Therefore, the implementation of the EE policy seems to be an exercise in futility. The absence of a policy guideline document has made teachers and school administrators incapacitated in the implementation of EE school policy. , Thesis (PhD) -- Faculty of Education, 2022
- Full Text:
- Date Issued: 2021-12
- Authors: Damoah, Benjamin
- Date: 2021-12
- Subjects: Environmental education , Environmental policy -- South Africa , Education and state -- South Africa
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10353/21602 , vital:51703
- Description: Environmental Education (EE) is essential for addressing environmental challenges.The advantages of EE are undeniable; it might be used to address specific environmental concerns and their implications, as well as to modify behaviours that lead to environmental catastrophes.EE strengthens people's resilience to climaterelated hazards. Global environmental issues have heightened interest in educational policy outcomes and their implications for economic growth and social citizenship. It is worth noting that an effective EE policy has a significant influence on the development of learners' environmental literacy. This study assessed the implementation of environmental education school policy in the Buffalo City Metro Education District, South Africa. This study adopted the pragmatism paradigm of Mixed Method Research(MMR). Concurrent triangulation, which is a design that employs a single data collection technique in which quantitative and qualitative data gathering and analysis are carried out independently yet concurrently, was used for this study. The target population of this study involved 60,412 teachers, 1,770,289 learners in 5205 public schools, and 1 Pro-EE civil society organisation in the Eastern Cape province. This was narrowed down to over 268 public and independent schools, teachers, and principals within the enclave of the Buffalo Metropolitan education district. The study adopted stratified purposeful and simple random probability sampling. In this technique, the sampling frame of the study was divided into strata or groups (principals, teachers, learners, and CSOs) and a sample was purposefully selected from each stratum (Migiro & Magangi, 2011). The stratified purposeful random sampling techniques draw data from 10 principals, 175 teachers, 1500 learners, and 1 CSO. Structured questionnaire; Implementation of EE Policy Questionnaire (IEEPQ) whose reliability co-efficient value using Cronbach Alpha was 0.74, semi-structured interview and documents were the instruments used to collect data for this study. The data were analysed using descriptive statistics of percentage, mean, and standard deviation for the quantitative data while the thematic approach of sorting, coding, transcribing, and categorization was used for the qualitative data. The study revealed the following. When asked whether teachers had studied environmental education in tertiary institutions as part of their professional training, the majority of the teachers'respondents, 108, representing 61.7percent, disagreed with this view. On the flip side, a handful of teachers 67, (38.3percent) agreed with the view of having had some sort of EE knowledge during their professional training as teachers. With regards to the view that learners learn environmental issues through other subjects, most of the learner respondents, 1316 representing 87.7percent, agreed with this view. On the contrary, a minority of the respondents 184 (12,3percent) had a dissenting opinion. This indicates that most learners in school learn about environmental concerns through other traditional subjects. The study established that EE content is manifest in teachers' and learners' textbooks, teaching methods, and co-curricular activities. However, the study identified lapses in how teachers and learners integrate EE into their day-to-day practices. Therefore, the implementation of the EE policy seems to be an exercise in futility. The absence of a policy guideline document has made teachers and school administrators incapacitated in the implementation of EE school policy. , Thesis (PhD) -- Faculty of Education, 2022
- Full Text:
- Date Issued: 2021-12
A case study of lessons learned through empowering and mobilizing unemployed youth into sustainable green jobs within the SANBI – Groen Sebenza partnership programme by a Host Institution in South Africa
- Authors: Fullard, Donovan
- Date: 2021-10-29
- Subjects: South African National Biodiversity Institute , Green movement South Africa , Environmental education South Africa , Communities of practice South Africa , Social learning South Africa , Biodiversity conservation Employees , Job creation South Africa , Mentoring South Africa , Groen Sebenza
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10962/191964 , vital:45183
- Description: This research project constituted as a thesis of limited scope for a Masters in Education Degree (i.e. as 50% of the degree) focusses on a job creation programme named ‘Groen Sebenza’ [Green Work]. Groen Sebenza is an environmental education ‘incubator’ programme driven and implemented by the South African National Biodiversity Institute (SANBI) to unlock green jobs and bridge the gap between education and job opportunities in the biodiversity sector in South Africa. The programme is a key intervention to strengthen biodiversity human capacity development in the biodiversity sector in South Africa, seeking to contribute to transformation of the biodiversity sector, and also address issues of youth unemployment in the country. The young ‘interns’ in the programme were called ‘pioneers’ at the start of the project. This research project explores how a host institution operating as a community of practice within a landscape of practice managed to implement the Groen Sebenza programme by absorbing and appointing all their pioneers into sustainable jobs beyond the pilot project. I sought to better understand the process of supporting and empowering unemployed youth into sustainable green jobs within the Groen Sebenza partnership programme. I drew on Community of Practice (CoP) theory, and its value creation framework to develop this understanding, and I under-laboured the analysis with a social realist analysis of enabling and constraining factors. The unit of analysis of a Community of Practice was a useful focus for the study, as these mentors, managers, and administrators were all involved in supporting the empowerment and retention of the young pioneers in the host institution. To develop deeper insight into the learning and knowing, and value created in and by the Groen Sebenza CoP in the Host Institution, I also sought insight into enabling and constraining factors and how these shaped and contributed to empowerment and retention of the pioneers in sustainable green jobs. The research addressed the main question of ‘How do processes of learning, knowing and value creation contribute to empowerment and retention of unemployed youth in a successful Host Institution in the Groen Sebenza programme, and what enabled or constrained the empowerment and retention processes and outcomes?’. Three sub-questions were used in the study, which focussed on the mentoring, training and workplace experiences and how they contribute to the process of learning and knowing within the Groen Sebenza Community of Practice in the Host Institution? [Addressed in Chapter 4], the value creation elements that emerged in the implementation of the programme in support and empowerment of the pioneers in the Host institution’s Groen Sebenza CoP? [Addressed in Chapter 5], and the enabling and constraining factors that shaped and contributed to the uptake of the Pioneers into sustainable green jobs at the Host Institution within the Groen Sebenza Programme? [Addressed in Chapter 6]. The research was conducted as a qualitative case study, in which I used semi-structured interviews as a key data source, as well as document analysis, and a questionnaire. The study drew on inductive, abductive and retroductive modes of inference since I sought to explore an understanding of the practices and learning that occurred that contributed and led to the successful uptake of Pioneers into jobs, as well as the enabling and constraining factors. The study was interpretive at the epistemic level, and had a social realist under-labouring at the ontological level. Key findings of the study point to the development of enabling cultures of mentoring in workplaces, and the provision of a diversity of workplace learning experiences including formal training. It also points to the importance of personal emergent properties amongst mentors and pioneers that embrace a willingness to work together and build strong relationships, and to learn together. Learning in the community of practice was shown to develop identity and a sense of belonging as pioneers were given meaningful tasks to do and their training and interactions with mentors was experienced as meaningful and relevant. The contributions of the pioneers to the institutional mandate was appreciated by the mentors and therefore also well supported within an empowerment orientation. Various structural factors contributed to this enabling situation, most notably strong support from management as well as good co-operation across divisions. Constraining factors included the physical distances in the province, as well as financial and technical issues such as poor ICT communication systems. Overall, though the study showed that a strong approach to learning in communities of practice supported by empowering mentoring can lead to the integration of young pioneers into sustainable green jobs in the environmental sector. A whole institution approach to this process is, however, needed, and the organisation needs to develop a culture of social learning. As recently as September 2020 as this study was being finalised, the Presidential Employment Stimulus Plan (Office of the President, 2020) following the initial economic shocks emanating from the COVID-19 pandemic, made yet another commitment to using the Groen Sebenza model to create and support sustainable job creation for young people in South Africa today in the environmental sector. This study has been developed and designed to understand those processes and enabling conditions that can support retention and empowerment of young people to take up jobs in the environmental sector today. Its recommendations may therefore be of value to those involved in seeking to support sustainable impacts in terms of retention and employment in programmes such as the Groen Sebenza, and in the Groen Sebenza programme itself as it continues to unfold as a key job creation tool for unemployed youth. , Thesis (MEd) -- Faculty of Education, Education, 2021
- Full Text:
- Date Issued: 2021-10-29
- Authors: Fullard, Donovan
- Date: 2021-10-29
- Subjects: South African National Biodiversity Institute , Green movement South Africa , Environmental education South Africa , Communities of practice South Africa , Social learning South Africa , Biodiversity conservation Employees , Job creation South Africa , Mentoring South Africa , Groen Sebenza
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10962/191964 , vital:45183
- Description: This research project constituted as a thesis of limited scope for a Masters in Education Degree (i.e. as 50% of the degree) focusses on a job creation programme named ‘Groen Sebenza’ [Green Work]. Groen Sebenza is an environmental education ‘incubator’ programme driven and implemented by the South African National Biodiversity Institute (SANBI) to unlock green jobs and bridge the gap between education and job opportunities in the biodiversity sector in South Africa. The programme is a key intervention to strengthen biodiversity human capacity development in the biodiversity sector in South Africa, seeking to contribute to transformation of the biodiversity sector, and also address issues of youth unemployment in the country. The young ‘interns’ in the programme were called ‘pioneers’ at the start of the project. This research project explores how a host institution operating as a community of practice within a landscape of practice managed to implement the Groen Sebenza programme by absorbing and appointing all their pioneers into sustainable jobs beyond the pilot project. I sought to better understand the process of supporting and empowering unemployed youth into sustainable green jobs within the Groen Sebenza partnership programme. I drew on Community of Practice (CoP) theory, and its value creation framework to develop this understanding, and I under-laboured the analysis with a social realist analysis of enabling and constraining factors. The unit of analysis of a Community of Practice was a useful focus for the study, as these mentors, managers, and administrators were all involved in supporting the empowerment and retention of the young pioneers in the host institution. To develop deeper insight into the learning and knowing, and value created in and by the Groen Sebenza CoP in the Host Institution, I also sought insight into enabling and constraining factors and how these shaped and contributed to empowerment and retention of the pioneers in sustainable green jobs. The research addressed the main question of ‘How do processes of learning, knowing and value creation contribute to empowerment and retention of unemployed youth in a successful Host Institution in the Groen Sebenza programme, and what enabled or constrained the empowerment and retention processes and outcomes?’. Three sub-questions were used in the study, which focussed on the mentoring, training and workplace experiences and how they contribute to the process of learning and knowing within the Groen Sebenza Community of Practice in the Host Institution? [Addressed in Chapter 4], the value creation elements that emerged in the implementation of the programme in support and empowerment of the pioneers in the Host institution’s Groen Sebenza CoP? [Addressed in Chapter 5], and the enabling and constraining factors that shaped and contributed to the uptake of the Pioneers into sustainable green jobs at the Host Institution within the Groen Sebenza Programme? [Addressed in Chapter 6]. The research was conducted as a qualitative case study, in which I used semi-structured interviews as a key data source, as well as document analysis, and a questionnaire. The study drew on inductive, abductive and retroductive modes of inference since I sought to explore an understanding of the practices and learning that occurred that contributed and led to the successful uptake of Pioneers into jobs, as well as the enabling and constraining factors. The study was interpretive at the epistemic level, and had a social realist under-labouring at the ontological level. Key findings of the study point to the development of enabling cultures of mentoring in workplaces, and the provision of a diversity of workplace learning experiences including formal training. It also points to the importance of personal emergent properties amongst mentors and pioneers that embrace a willingness to work together and build strong relationships, and to learn together. Learning in the community of practice was shown to develop identity and a sense of belonging as pioneers were given meaningful tasks to do and their training and interactions with mentors was experienced as meaningful and relevant. The contributions of the pioneers to the institutional mandate was appreciated by the mentors and therefore also well supported within an empowerment orientation. Various structural factors contributed to this enabling situation, most notably strong support from management as well as good co-operation across divisions. Constraining factors included the physical distances in the province, as well as financial and technical issues such as poor ICT communication systems. Overall, though the study showed that a strong approach to learning in communities of practice supported by empowering mentoring can lead to the integration of young pioneers into sustainable green jobs in the environmental sector. A whole institution approach to this process is, however, needed, and the organisation needs to develop a culture of social learning. As recently as September 2020 as this study was being finalised, the Presidential Employment Stimulus Plan (Office of the President, 2020) following the initial economic shocks emanating from the COVID-19 pandemic, made yet another commitment to using the Groen Sebenza model to create and support sustainable job creation for young people in South Africa today in the environmental sector. This study has been developed and designed to understand those processes and enabling conditions that can support retention and empowerment of young people to take up jobs in the environmental sector today. Its recommendations may therefore be of value to those involved in seeking to support sustainable impacts in terms of retention and employment in programmes such as the Groen Sebenza, and in the Groen Sebenza programme itself as it continues to unfold as a key job creation tool for unemployed youth. , Thesis (MEd) -- Faculty of Education, Education, 2021
- Full Text:
- Date Issued: 2021-10-29
Transformative, transgressive social learning: Rethinking higher education pedagogy in times of systemic global dysfunction
- Lotz-Sisitka, Heila, Wals, Arjen E J, Kronlid, David O, McGarry, Dylan K
- Authors: Lotz-Sisitka, Heila , Wals, Arjen E J , Kronlid, David O , McGarry, Dylan K
- Date: 2015
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/372794 , vital:66623 , xlink:href="https://doi.org/10.1016/j.cosust.2015.07.018"
- Description: The nature of the sustainability challenges currently at hand is such that dominant pedagogies and forms of learning that characterize higher education need to be reconsidered to enable students and staff to deal with accelerating change, increasing complexity, contested knowledge claims and inevitable uncertainty. In this contribution we identified four streams of emerging transformative, transgressive learning research and praxis in the sustainability sciences that appear generative of a higher education pedagogy that appears more responsive to the key challenges of our time: (1) reflexive social learning and capabilities theory, (2) critical phenomenology, (3) socio-cultural and cultural historical activity theory, and (4) new social movement, postcolonial and decolonisation theory. The paper critiques the current tendency in sustainability science and learning to rely on resilience and adaptive capacity building and argues that in order to break with maladaptive resilience of unsustainable systems it is essential to strengthen transgressive learning and disruptive capacity-building.
- Full Text:
- Date Issued: 2015
- Authors: Lotz-Sisitka, Heila , Wals, Arjen E J , Kronlid, David O , McGarry, Dylan K
- Date: 2015
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/372794 , vital:66623 , xlink:href="https://doi.org/10.1016/j.cosust.2015.07.018"
- Description: The nature of the sustainability challenges currently at hand is such that dominant pedagogies and forms of learning that characterize higher education need to be reconsidered to enable students and staff to deal with accelerating change, increasing complexity, contested knowledge claims and inevitable uncertainty. In this contribution we identified four streams of emerging transformative, transgressive learning research and praxis in the sustainability sciences that appear generative of a higher education pedagogy that appears more responsive to the key challenges of our time: (1) reflexive social learning and capabilities theory, (2) critical phenomenology, (3) socio-cultural and cultural historical activity theory, and (4) new social movement, postcolonial and decolonisation theory. The paper critiques the current tendency in sustainability science and learning to rely on resilience and adaptive capacity building and argues that in order to break with maladaptive resilience of unsustainable systems it is essential to strengthen transgressive learning and disruptive capacity-building.
- Full Text:
- Date Issued: 2015
A political economy of transformation in Nelson Mandela University Bay: a critical analysis of the construction sector 2005
- Authors: Mtimka, Ongama
- Date: 2022-12
- Subjects: Transformation -- Port Elizabeth -- Nelson Mandela Bay , Construction industry -- South Africa –Port Elizabeth , Politics -- Nelson Mandela Bay
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10948/59392 , vital:62077
- Description: In democracies and purportedly free market economies, questions of “who gets what, when, and how” ought to be resolved mainly through free competition, where those with the competitive advantage on merit are guaranteed to succeed. If it is political parties, they only have to compete well and fairly to win elections. If it is businesses, they ought to have the best value and price and they win customers. However, there are institutions which regulate this competition and political economic behaviour. Interest groups such as business chambers, industry and professional associations, as well as various structures of representation engage in the political economic space to sway the distribution outcomes from these “institutions” in the favour of their members. To do so, at times they use methods that affirm the principles and spirit of free competition and at other times, they do not. This thesis reviews the political economy of transformation within the construction sector in Nelson Mandela Bay to further advance knowledge within the subfield of political economy in South Africa. By looking at a specific economic sector, the study adds an important element to the sub-discipline, a nuance to the debates about the role of the state in the economy or macroeconomic policy and the much studied mining-energy complex. The study focuses on the role of small business forums created mostly by newcomers within the construction sector in the city and the methods they used to increase the share of their members in construction sector revenues. Their methods were unconventional and earned them the unfavourable term of ‘the construction mafia’. Through a grounded theoretical research process, this study details the story of the rise and fall of forums and dissects it in line with ongoing debates within political economy and related disciplines, particularly about the nexus between politics and business as well as the role of interest groups in pluralist political systems. Among other things, the study finds that the forums did not see the construction industry as a free market and did not take principles of competition in the sector as a given. As such, they sought to make and remake institutions of the sector in ways that could increase their share of revenues. In similar fashion to the roles of iinjoli nosokhaya in traditional isiXhosa ceremonies, they accorded to themselves the right to distribute benefits to their members contrary to legal and general market prescripts. , Thesis (PhD) -- Faculty of Humanities, School of Government and Social sciences, 2022
- Full Text:
- Date Issued: 2022-12
- Authors: Mtimka, Ongama
- Date: 2022-12
- Subjects: Transformation -- Port Elizabeth -- Nelson Mandela Bay , Construction industry -- South Africa –Port Elizabeth , Politics -- Nelson Mandela Bay
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10948/59392 , vital:62077
- Description: In democracies and purportedly free market economies, questions of “who gets what, when, and how” ought to be resolved mainly through free competition, where those with the competitive advantage on merit are guaranteed to succeed. If it is political parties, they only have to compete well and fairly to win elections. If it is businesses, they ought to have the best value and price and they win customers. However, there are institutions which regulate this competition and political economic behaviour. Interest groups such as business chambers, industry and professional associations, as well as various structures of representation engage in the political economic space to sway the distribution outcomes from these “institutions” in the favour of their members. To do so, at times they use methods that affirm the principles and spirit of free competition and at other times, they do not. This thesis reviews the political economy of transformation within the construction sector in Nelson Mandela Bay to further advance knowledge within the subfield of political economy in South Africa. By looking at a specific economic sector, the study adds an important element to the sub-discipline, a nuance to the debates about the role of the state in the economy or macroeconomic policy and the much studied mining-energy complex. The study focuses on the role of small business forums created mostly by newcomers within the construction sector in the city and the methods they used to increase the share of their members in construction sector revenues. Their methods were unconventional and earned them the unfavourable term of ‘the construction mafia’. Through a grounded theoretical research process, this study details the story of the rise and fall of forums and dissects it in line with ongoing debates within political economy and related disciplines, particularly about the nexus between politics and business as well as the role of interest groups in pluralist political systems. Among other things, the study finds that the forums did not see the construction industry as a free market and did not take principles of competition in the sector as a given. As such, they sought to make and remake institutions of the sector in ways that could increase their share of revenues. In similar fashion to the roles of iinjoli nosokhaya in traditional isiXhosa ceremonies, they accorded to themselves the right to distribute benefits to their members contrary to legal and general market prescripts. , Thesis (PhD) -- Faculty of Humanities, School of Government and Social sciences, 2022
- Full Text:
- Date Issued: 2022-12
Sequence, structure, dynamics, and substrate specificity analyses of bacterial Glycoside Hydrolase 1 enzymes from several activities
- Authors: Veldman, Wayde Michael
- Date: 2022-04-08
- Subjects: Glycosidases , Bioinformatics , Molecular dynamics , Ligands (Biochemistry) , Enzymes , Ligand binding (Biochemistry) , Sequence alignment (Bioinformatics) , Structural bioinformatics
- Language: English
- Type: Doctoral thesis , text
- Identifier: http://hdl.handle.net/10962/233805 , vital:50129 , DOI 10.21504/10962/233810
- Description: Glycoside hydrolase 1 (GH1) enzymes are a ubiquitous family of enzymes that hydrolyse the glycosidic bond between two or more carbohydrates, or between a carbohydrate and a non-carbohydrate moiety. Despite their conserved catalytic domain, these enzymes have many different enzyme activities and/or substrate specificities as a change of only a few residues in the active site can alter their function. Most GH1 active site residues are situated in loop regions, and it is known that enzymes are more likely to develop new functions (broad specificity) if they possess an active site with a high proportion of loops. Furthermore, the GH1 active site consists of several subsites and cooperative binding makes the binding affinity of sites difficult to measure because the properties of one subsite are influenced by the binding of the other subsites. Extensive knowledge of protein-ligand interactions is critical to the comprehension of biology at the molecular level. However, the structural determinants and molecular details of GH1 ligand specificity and affinity are very broad, highly complex, not well understood, and therefore still need to be clarified. The aim of this study was to computationally characterise the activity of three newly solved GH1 crystallographic structures sent to us by our collaborators, and to provide evidence for their ligand-binding specificities. In addition, the differences in structural and biochemical contributions to enzyme specificity and/or function between different GH1 activities/enzymes was assessed, and the sequence/structure/function relationship of several activities of GH1 enzymes was analysed and compared. To accomplish the research aims, sequence analyses involving sequence identity, phylogenetics, and motif discovery were performed. As protein structure is more conserved than sequence, the discovered motifs were mapped to 3D structures for structural analysis and comparisons. To obtain information on enzyme mechanism or mode of action, as well as structure-function relationship, computational methods such as docking, molecular dynamics, binding free energy calculations, and essential dynamics were implemented. These computational approaches can provide information on the active site, binding residues, protein-ligand interactions, binding affinity, conformational change, and most structural or dynamic elements that play a role in enzyme function. The three new structures received from our collaborators are the first GH1 crystallographic structures from Bacillus licheniformis ever determined. As phospho-glycoside compounds were unavailable for purchase for use in activity assays, and as the active sites of the structures were absent of ligand, in silico docking and MD simulations were performed to provide evidence for their GH1 activities and substrate specificities. First though, the amino acid sequences of all known characterised bacterial GH1 enzymes were retrieved from the CAZy database and compared to the sequences of the three new B. licheniformis crystallographic structures which provided evidence of the putative 6Pβ-glucosidase activity of enzyme BlBglH, and dual 6Pβ-glucosidase/6Pβ-galactosidase (dual-phospho) activity of enzymes BlBglB and BlBglC. As all three enzymes were determined to be putative 6Pβ-glycosidase activity enzymes, much of the thesis focused on the overall analysis and comparison of the 6Pβ-glucosidase, 6Pβ-galactosidase, and dual-phospho activities that make up the 6Pβ-glycosidases. The 6Pβ-glycosidase active site residues were identified through consensus of binding interactions using all known 6Pβ-glycosidase PDB structures complexed complete ligand substrates. With regards to the 6Pβ-glucosidase activity, it was found that the L8b loop is longer and forms extra interactions with the L8a loop likely leading to increased L8 loop rigidity which would prevent the displacement of residue Ala423 ensuring a steric clash with galactoconfigured ligands and may engender substrate specificity for gluco-configured ligands only. Also, during molecular dynamics simulations using enzyme BlBglH (6Pβ-glucosidase activity), it was revealed that the favourable binding of substrate stabilises the loops that surround and make up the enzyme active site. Using the BlBglC (dual-phospho activity) enzyme structure with either galacto- (PNP6Pgal) or gluco-configured (PNP6Pglc) ligands, MD simulations in triplicate revealed important details of the broad specificity of dual-phospho activity enzymes. The ligand O4 hydroxyl position is the only difference between PNP6Pgal and PNP6Pgal, and it was found that residues Gln23 and Trp433 bind strongly to the ligand O3 hydroxyl group in the PNP6Pgal-enzyme complex, but to the ligand O4 hydroxyl group in the PNP6Pglc-enzyme complex. Also, His124 formed many hydrogen bonds with the PNP6Pgal O3 hydroxyl group but had none with PNP6Pglc. Alternatively, residues Tyr173, Tyr301, Gln302 and Thr321 formed hydrogen bonds with PNP6Pglc but not PNP6Pgal. Lastly, using multiple 3D structures from various GH1 activities, a large network of conserved interactions between active site residues (and other important residues) was uncovered, which most likely stabilise the loop regions that contain these residues, helping to retain their positions needed for binding molecules. Alternatively, there exists several differing residue-residue interactions when comparing each of the activities which could contribute towards individual activity substrate specificity by causing slightly different overall structure and malleability of the active site. Altogether, the findings in this thesis shed light on the function, mechanisms, dynamics, and ligand-binding of GH1 enzymes – particularly of the 6Pβ-glycosidase activities. , Thesis (PhD) -- Faculty of Science, Biochemistry and Microbiology, 2022
- Full Text:
- Date Issued: 2022-04-08
- Authors: Veldman, Wayde Michael
- Date: 2022-04-08
- Subjects: Glycosidases , Bioinformatics , Molecular dynamics , Ligands (Biochemistry) , Enzymes , Ligand binding (Biochemistry) , Sequence alignment (Bioinformatics) , Structural bioinformatics
- Language: English
- Type: Doctoral thesis , text
- Identifier: http://hdl.handle.net/10962/233805 , vital:50129 , DOI 10.21504/10962/233810
- Description: Glycoside hydrolase 1 (GH1) enzymes are a ubiquitous family of enzymes that hydrolyse the glycosidic bond between two or more carbohydrates, or between a carbohydrate and a non-carbohydrate moiety. Despite their conserved catalytic domain, these enzymes have many different enzyme activities and/or substrate specificities as a change of only a few residues in the active site can alter their function. Most GH1 active site residues are situated in loop regions, and it is known that enzymes are more likely to develop new functions (broad specificity) if they possess an active site with a high proportion of loops. Furthermore, the GH1 active site consists of several subsites and cooperative binding makes the binding affinity of sites difficult to measure because the properties of one subsite are influenced by the binding of the other subsites. Extensive knowledge of protein-ligand interactions is critical to the comprehension of biology at the molecular level. However, the structural determinants and molecular details of GH1 ligand specificity and affinity are very broad, highly complex, not well understood, and therefore still need to be clarified. The aim of this study was to computationally characterise the activity of three newly solved GH1 crystallographic structures sent to us by our collaborators, and to provide evidence for their ligand-binding specificities. In addition, the differences in structural and biochemical contributions to enzyme specificity and/or function between different GH1 activities/enzymes was assessed, and the sequence/structure/function relationship of several activities of GH1 enzymes was analysed and compared. To accomplish the research aims, sequence analyses involving sequence identity, phylogenetics, and motif discovery were performed. As protein structure is more conserved than sequence, the discovered motifs were mapped to 3D structures for structural analysis and comparisons. To obtain information on enzyme mechanism or mode of action, as well as structure-function relationship, computational methods such as docking, molecular dynamics, binding free energy calculations, and essential dynamics were implemented. These computational approaches can provide information on the active site, binding residues, protein-ligand interactions, binding affinity, conformational change, and most structural or dynamic elements that play a role in enzyme function. The three new structures received from our collaborators are the first GH1 crystallographic structures from Bacillus licheniformis ever determined. As phospho-glycoside compounds were unavailable for purchase for use in activity assays, and as the active sites of the structures were absent of ligand, in silico docking and MD simulations were performed to provide evidence for their GH1 activities and substrate specificities. First though, the amino acid sequences of all known characterised bacterial GH1 enzymes were retrieved from the CAZy database and compared to the sequences of the three new B. licheniformis crystallographic structures which provided evidence of the putative 6Pβ-glucosidase activity of enzyme BlBglH, and dual 6Pβ-glucosidase/6Pβ-galactosidase (dual-phospho) activity of enzymes BlBglB and BlBglC. As all three enzymes were determined to be putative 6Pβ-glycosidase activity enzymes, much of the thesis focused on the overall analysis and comparison of the 6Pβ-glucosidase, 6Pβ-galactosidase, and dual-phospho activities that make up the 6Pβ-glycosidases. The 6Pβ-glycosidase active site residues were identified through consensus of binding interactions using all known 6Pβ-glycosidase PDB structures complexed complete ligand substrates. With regards to the 6Pβ-glucosidase activity, it was found that the L8b loop is longer and forms extra interactions with the L8a loop likely leading to increased L8 loop rigidity which would prevent the displacement of residue Ala423 ensuring a steric clash with galactoconfigured ligands and may engender substrate specificity for gluco-configured ligands only. Also, during molecular dynamics simulations using enzyme BlBglH (6Pβ-glucosidase activity), it was revealed that the favourable binding of substrate stabilises the loops that surround and make up the enzyme active site. Using the BlBglC (dual-phospho activity) enzyme structure with either galacto- (PNP6Pgal) or gluco-configured (PNP6Pglc) ligands, MD simulations in triplicate revealed important details of the broad specificity of dual-phospho activity enzymes. The ligand O4 hydroxyl position is the only difference between PNP6Pgal and PNP6Pgal, and it was found that residues Gln23 and Trp433 bind strongly to the ligand O3 hydroxyl group in the PNP6Pgal-enzyme complex, but to the ligand O4 hydroxyl group in the PNP6Pglc-enzyme complex. Also, His124 formed many hydrogen bonds with the PNP6Pgal O3 hydroxyl group but had none with PNP6Pglc. Alternatively, residues Tyr173, Tyr301, Gln302 and Thr321 formed hydrogen bonds with PNP6Pglc but not PNP6Pgal. Lastly, using multiple 3D structures from various GH1 activities, a large network of conserved interactions between active site residues (and other important residues) was uncovered, which most likely stabilise the loop regions that contain these residues, helping to retain their positions needed for binding molecules. Alternatively, there exists several differing residue-residue interactions when comparing each of the activities which could contribute towards individual activity substrate specificity by causing slightly different overall structure and malleability of the active site. Altogether, the findings in this thesis shed light on the function, mechanisms, dynamics, and ligand-binding of GH1 enzymes – particularly of the 6Pβ-glycosidase activities. , Thesis (PhD) -- Faculty of Science, Biochemistry and Microbiology, 2022
- Full Text:
- Date Issued: 2022-04-08
Coaches perspective on the positional demands of school boy (u18/u19) rugby players during a 70-minute match
- Authors: Barnard, Devon Vernon
- Date: 2021-10
- Subjects: Rugby football coaches South Africa , Rugby Union football players South Africa , Rugby football injuries South Africa , School sports South Africa , School sports Coaching South Africa , School sports Physiological aspects
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10962/190089 , vital:44962
- Description: INTRODUCTION: Rugby union has been one of the team sports that has grown over the last few years, and the margin between success and failure for teams has become narrower as the years have gone by. The game consists of players going through different movements such as sprints and/or collisions, that vary in intensity. The demands that face schoolboy rugby players are not well understood, and the lack of research in this area leads to a potential lack of understanding of the perceptions that coaches have about the demands that schoolboys are faced with during a match. OBJECTIVE: Therefore, the purpose of this study was to determine the perceptions that the schoolboy rugby coaches had surrounding the demands that their players are faced with during a 70-minute match. There were a few secondary purposes of the study, such as determining which school, government or private, had a better understanding or perception of the demands, as well as comparing strength and conditioning coaches’ perceptions to regular coaches’ perceptions. METHODS: This was a cross-sectional, descriptive study to determine the coach’s perceptions. These perceptions were collected through an online questionnaire, which consisted of ten sections and 74 questions. The questionnaire was piloted on a subject group with different types of experience. Coaches from the top 100 schools list were contacted through their school website. RESULTS: The questionnaire had a 72% response rate: 41 responses from 51 emails. The 41 responses consisted of 23 government schools and 18 private schools, which included 11 of the top 20 rugby schools in South Africa, with most responses coming from the Eastern Cape (41.5%). Results indicated that a government school’s coaches had significantly (p<0.05) more experience than private schools’ coaches, and that they had significantly (p<0.05) better academic qualifications than private schools. However, strength and conditioning coaches had significantly (p<0.01) better academic qualifications than coach, whereas coaches had significantly (p<0.01) better coaching qualifications than strength and conditioning coaches. CONCLUSION: “Experience has been shown to be a potential reason for what is described as a good coach”. This is also another potential reason why government schools are a dominant force in schoolboy rugby in South Africa. However, this is also coupled with better qualifications showing the dual importance of both experience and education. This study has shown that coaches, within a South African cohort, overall had good general perception of the demands of school level rugby matches. , Thesis (MSc) -- Faculty of Science, Human Kinetics and Ergonomics, 2021
- Full Text:
- Date Issued: 2021-10
- Authors: Barnard, Devon Vernon
- Date: 2021-10
- Subjects: Rugby football coaches South Africa , Rugby Union football players South Africa , Rugby football injuries South Africa , School sports South Africa , School sports Coaching South Africa , School sports Physiological aspects
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10962/190089 , vital:44962
- Description: INTRODUCTION: Rugby union has been one of the team sports that has grown over the last few years, and the margin between success and failure for teams has become narrower as the years have gone by. The game consists of players going through different movements such as sprints and/or collisions, that vary in intensity. The demands that face schoolboy rugby players are not well understood, and the lack of research in this area leads to a potential lack of understanding of the perceptions that coaches have about the demands that schoolboys are faced with during a match. OBJECTIVE: Therefore, the purpose of this study was to determine the perceptions that the schoolboy rugby coaches had surrounding the demands that their players are faced with during a 70-minute match. There were a few secondary purposes of the study, such as determining which school, government or private, had a better understanding or perception of the demands, as well as comparing strength and conditioning coaches’ perceptions to regular coaches’ perceptions. METHODS: This was a cross-sectional, descriptive study to determine the coach’s perceptions. These perceptions were collected through an online questionnaire, which consisted of ten sections and 74 questions. The questionnaire was piloted on a subject group with different types of experience. Coaches from the top 100 schools list were contacted through their school website. RESULTS: The questionnaire had a 72% response rate: 41 responses from 51 emails. The 41 responses consisted of 23 government schools and 18 private schools, which included 11 of the top 20 rugby schools in South Africa, with most responses coming from the Eastern Cape (41.5%). Results indicated that a government school’s coaches had significantly (p<0.05) more experience than private schools’ coaches, and that they had significantly (p<0.05) better academic qualifications than private schools. However, strength and conditioning coaches had significantly (p<0.01) better academic qualifications than coach, whereas coaches had significantly (p<0.01) better coaching qualifications than strength and conditioning coaches. CONCLUSION: “Experience has been shown to be a potential reason for what is described as a good coach”. This is also another potential reason why government schools are a dominant force in schoolboy rugby in South Africa. However, this is also coupled with better qualifications showing the dual importance of both experience and education. This study has shown that coaches, within a South African cohort, overall had good general perception of the demands of school level rugby matches. , Thesis (MSc) -- Faculty of Science, Human Kinetics and Ergonomics, 2021
- Full Text:
- Date Issued: 2021-10