Performance assessment of infrastructure and housing contractors in Buffalo City
- Ngqinambi, Thomakazi Thobeka
- Authors: Ngqinambi, Thomakazi Thobeka
- Date: 2018
- Subjects: Performance standards , Construction industry -- South Africa -- Management Contractors' operations Organizational effectiveness
- Language: English
- Type: Thesis , Masters , MBA
- Identifier: http://hdl.handle.net/10948/33682 , vital:32964
- Description: It is evident that contractors in Buffalo City Metro Municipality are not successfully executing the projects appropriately. The effects can be a result of factors contributing to poor performance. Expenditure trends tell a frightening story in relation to the performance of the contractors as the main spenders on capital and operating project budgets. The municipality is faced with projects that have time and cost overruns, poor project implementation and total abandonment. There is no proper performance measurement instrument in place; as a result, the council struggles to terminate poor performing contractors. This study focuses on key performance indicators that can be employed by the municipality to measure performance of contractors and evaluate progress. Also this study outlined the factors affecting contractor performance during construction so as to understand the effects of these factors on the performance. A questionnaire was utilised to collect information from construction stakeholders. In order for contractors to improve their overall performance, focus should be on construction time and cost. Clients must improve on speed of decision-making during construction.
- Full Text:
- Date Issued: 2018
- Authors: Ngqinambi, Thomakazi Thobeka
- Date: 2018
- Subjects: Performance standards , Construction industry -- South Africa -- Management Contractors' operations Organizational effectiveness
- Language: English
- Type: Thesis , Masters , MBA
- Identifier: http://hdl.handle.net/10948/33682 , vital:32964
- Description: It is evident that contractors in Buffalo City Metro Municipality are not successfully executing the projects appropriately. The effects can be a result of factors contributing to poor performance. Expenditure trends tell a frightening story in relation to the performance of the contractors as the main spenders on capital and operating project budgets. The municipality is faced with projects that have time and cost overruns, poor project implementation and total abandonment. There is no proper performance measurement instrument in place; as a result, the council struggles to terminate poor performing contractors. This study focuses on key performance indicators that can be employed by the municipality to measure performance of contractors and evaluate progress. Also this study outlined the factors affecting contractor performance during construction so as to understand the effects of these factors on the performance. A questionnaire was utilised to collect information from construction stakeholders. In order for contractors to improve their overall performance, focus should be on construction time and cost. Clients must improve on speed of decision-making during construction.
- Full Text:
- Date Issued: 2018
Performance comparison of the residential types of air source heat pump water heaters in South Africa due to the refrigerant thermo-physical properties
- Authors: Sikhonza, Mandlenkosi
- Date: 2018
- Subjects: Heat pumps Water heaters
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10353/9275 , vital:34317
- Description: Globally hot water heating contributes enormously to the increase in energy consumption in the residential sector. Coal being a fossil fuel and non-renewable source of energy remains the major source used for electricity generation. The burning of coal is the primary cause of CO2 emission into the environment which causes climate change and global warming. Energy efficiency and renewable energy technologies were employed as one of the alternative ways of reducing global warming. In most residential areas in South Africa, the water heating generates 30 -50percent of the monthly electricity bill (Zhang and Huan, 2013). In this light, residential load management (RLM) is a significant part of the load management programme of Eskom’s overall demand side management strategy. Through RLM, the electricity load is being transferred from peak times to off times by switching the geysers during peak hours because geysers consume more electricity and contribute significantly to the national grid constraint problem (Eskom, 2012).
- Full Text:
- Date Issued: 2018
- Authors: Sikhonza, Mandlenkosi
- Date: 2018
- Subjects: Heat pumps Water heaters
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10353/9275 , vital:34317
- Description: Globally hot water heating contributes enormously to the increase in energy consumption in the residential sector. Coal being a fossil fuel and non-renewable source of energy remains the major source used for electricity generation. The burning of coal is the primary cause of CO2 emission into the environment which causes climate change and global warming. Energy efficiency and renewable energy technologies were employed as one of the alternative ways of reducing global warming. In most residential areas in South Africa, the water heating generates 30 -50percent of the monthly electricity bill (Zhang and Huan, 2013). In this light, residential load management (RLM) is a significant part of the load management programme of Eskom’s overall demand side management strategy. Through RLM, the electricity load is being transferred from peak times to off times by switching the geysers during peak hours because geysers consume more electricity and contribute significantly to the national grid constraint problem (Eskom, 2012).
- Full Text:
- Date Issued: 2018
Performance evaluation and cost analysis of subsurface flow constructed wetlands designed for ammonium-nitrogen removal
- Authors: Tebitendwa, Sylvie Muwanga
- Date: 2018
- Subjects: Sewage Purification Nitrogen removal , Constructed wetlands , Bioremediation , Sewage lagoons , Coal mine waste
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/61808 , vital:28062
- Description: Subsurface flow constructed wetlands (SSF CWs) is a low-cost, environmentally friendly sanitation technology for on-site treatment of domestic/municipal sewage. However, these systems are apparently unable to produce treated water of a quality suitable for discharge particularly in terms of nitrogen concentration, which has been attributed to design and operation based on biological oxygen demand as the parameter of choice. The aim of this study was to evaluate the performance, support medium, and techno-economics of a vertical- horizontal (V-H) SSF hybrid CW designed and operated using ammonium-nitrogen (NH4+-N) as the major parameter. Two pilot scale V-H SSF hybrid CWs were designed, constructed, and the performance of each monitored over two seasons and under two phases i.e. an initiation phase, and an optimization phase. Laboratory-scale horizontal SSF CWs were used to evaluate the support medium while the techno-economic study was framed to determine the cost effectiveness of V-H SSF hybrid CWs relative to high rate algal oxidation pond (HRAOP) systems to increase capacity of overloaded and/or under-performing waste stabilization pond (WSP) sewage treatment plants. Results revealed that under optimal operating conditions of hydraulic loading rate, hydraulic retention, and influent NH4+-N loading rate, treated water from the V-H SSF hybrid CWs achieved a quality commensurate with current South African standards for discharge into a surface water resource for all parameters except chemical oxygen demand and faecal coliforms. This suggests that NH4+-N is an important design and operational parameter for SSF CWs treating municipal sewage that is characterised as weak in terms of NH4+-N with a requirement of only simple disinfection such as chlorination to eliminate faecal coliforms. Use of discard coal to replace gravel as support medium in horizontal SSF CWs revealed an overall reduction in elemental composition of the discard coal support medium but without compromising water quality. This result strongly supports use of discard coal as an appropriate substrate for SSF CWs to achieve acceptable water quality. Furthermore, simultaneous degradation of discard coal during wastewater treatment demonstrates the versatility of SSF CWs for use in bio-remediation and pollution control. Finally, a technoeconomic assessment of V-H SSF hybrid CWs and a HRAOP series was carried out to determine the suitability of each process to increase capacity by mitigating dysfunctional and/or overloaded WSP sewage treatment plants. Analysis revealed that the quality of treated water from both systems was within the South African General Authorization standards for discharge to a surface water resource. Even so, each technology system presented its own set of limitations including; the inability to satisfactorily remove NH4+-N and chemical oxygen demand (i.e. for V-H SSF hybrid CWs) and total suspended solids and faecal coliforms (i.e. for HRAOPs), and a requirement for substantial land footprint while, HRAOPs required significantly less capital than V-H SSF hybrid CWs for implementation. The latter suggests that HRAOPs could be preferred over V-H SSF hybrid CWs as a technology of choice to increase the capacity of overloaded WSP sewage treatment plants especially where financial resources are limited. Overall, the results of this thesis indicate the potential to use NH4+-N as a design parameter in constructing SSF CWs treating weak strength municipal sewage (i.e. in terms of NH4+-N concentration) and to supplant gravel as the treatment media with industrial waste material like discard coal to achieve wastewater treatment, bio-remediation, and pollution control. The results of this work are discussed in terms of using SSF CWs as a passive and resilient technology for the treatment of domestic sewage in sub-Saharan Africa.
- Full Text:
- Date Issued: 2018
- Authors: Tebitendwa, Sylvie Muwanga
- Date: 2018
- Subjects: Sewage Purification Nitrogen removal , Constructed wetlands , Bioremediation , Sewage lagoons , Coal mine waste
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/61808 , vital:28062
- Description: Subsurface flow constructed wetlands (SSF CWs) is a low-cost, environmentally friendly sanitation technology for on-site treatment of domestic/municipal sewage. However, these systems are apparently unable to produce treated water of a quality suitable for discharge particularly in terms of nitrogen concentration, which has been attributed to design and operation based on biological oxygen demand as the parameter of choice. The aim of this study was to evaluate the performance, support medium, and techno-economics of a vertical- horizontal (V-H) SSF hybrid CW designed and operated using ammonium-nitrogen (NH4+-N) as the major parameter. Two pilot scale V-H SSF hybrid CWs were designed, constructed, and the performance of each monitored over two seasons and under two phases i.e. an initiation phase, and an optimization phase. Laboratory-scale horizontal SSF CWs were used to evaluate the support medium while the techno-economic study was framed to determine the cost effectiveness of V-H SSF hybrid CWs relative to high rate algal oxidation pond (HRAOP) systems to increase capacity of overloaded and/or under-performing waste stabilization pond (WSP) sewage treatment plants. Results revealed that under optimal operating conditions of hydraulic loading rate, hydraulic retention, and influent NH4+-N loading rate, treated water from the V-H SSF hybrid CWs achieved a quality commensurate with current South African standards for discharge into a surface water resource for all parameters except chemical oxygen demand and faecal coliforms. This suggests that NH4+-N is an important design and operational parameter for SSF CWs treating municipal sewage that is characterised as weak in terms of NH4+-N with a requirement of only simple disinfection such as chlorination to eliminate faecal coliforms. Use of discard coal to replace gravel as support medium in horizontal SSF CWs revealed an overall reduction in elemental composition of the discard coal support medium but without compromising water quality. This result strongly supports use of discard coal as an appropriate substrate for SSF CWs to achieve acceptable water quality. Furthermore, simultaneous degradation of discard coal during wastewater treatment demonstrates the versatility of SSF CWs for use in bio-remediation and pollution control. Finally, a technoeconomic assessment of V-H SSF hybrid CWs and a HRAOP series was carried out to determine the suitability of each process to increase capacity by mitigating dysfunctional and/or overloaded WSP sewage treatment plants. Analysis revealed that the quality of treated water from both systems was within the South African General Authorization standards for discharge to a surface water resource. Even so, each technology system presented its own set of limitations including; the inability to satisfactorily remove NH4+-N and chemical oxygen demand (i.e. for V-H SSF hybrid CWs) and total suspended solids and faecal coliforms (i.e. for HRAOPs), and a requirement for substantial land footprint while, HRAOPs required significantly less capital than V-H SSF hybrid CWs for implementation. The latter suggests that HRAOPs could be preferred over V-H SSF hybrid CWs as a technology of choice to increase the capacity of overloaded WSP sewage treatment plants especially where financial resources are limited. Overall, the results of this thesis indicate the potential to use NH4+-N as a design parameter in constructing SSF CWs treating weak strength municipal sewage (i.e. in terms of NH4+-N concentration) and to supplant gravel as the treatment media with industrial waste material like discard coal to achieve wastewater treatment, bio-remediation, and pollution control. The results of this work are discussed in terms of using SSF CWs as a passive and resilient technology for the treatment of domestic sewage in sub-Saharan Africa.
- Full Text:
- Date Issued: 2018
Performance evaluation of an off-grid building integrated photovoltaic system in Alice, Eastern Cape province, South Africa
- Authors: Buma, Carine Lethem
- Date: 2018
- Subjects: Building-integrated photovoltaic systems Buildings -- Energy conservation Performance -- Evaluation
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10353/13227 , vital:39623
- Description: The constant increase in the global demand for energy and the current crisis on global warming and climate change has prompted a dying quest for clean, sustainable and reliable sources of energy. Amongst numerous renewable energy technologies, harnessing energy from the sun is the most viable way of guaranteeing a clean and sustainable supply of energy. Also, photovoltaic energy is one of the ways of using energy from the sun, where sunlight is converted to electricity using photovoltaic panels. Furthermore, the integration of photovoltaic modules into buildings is one of the most elegant innovations of this technology, as it plays the dual role of supplying energy to the building as well as protecting the building from outdoor weather conditions. Moreover, operating off the grid offers the possibility of energy access to locations far off from the grid and individuals willing to gain some degree of energy independence. Evaluating the performance of existing off grid and/or building integrated photovoltaic systems is the key to guaranteeing sustainable development and advancement in the technology. Thus, the aim of this work was to evaluate the performance of an off-grid building integrated photovoltaic system that was installed at the Fort Hare Institute of Technology. This entailed performing an in-depth characterisation of the solar resource at this location, evaluating the performance of the modules under outdoor weather conditions and also evaluating the performance of the balance of system (BOS) components. The system was monitored for a period of nine months (between February and October 2017). A data acquisition system was designed for measuring and recording both electrical system parameters and meteorological parameters affecting the performance of the system. These meteorological parameters include; solar irradiance, ambient temperature, cell temperature, relative humidity, wind speed and direction. A detailed characterisation of the solar resource at this location was carried out. It was observed that the solar declination angle varied from -23.5o on the summer solstice to 23.5o on the winter solstice. Also, the solar altitude angle (at solar noon) which is a complementary angle to the zenith angle varied from 33.7o in June to 80.65o in December. During the summer months, longer day lengths were experienced because the sun traversed the sky over a longer time, rising south of east and setting south of west. Whereas, in the winter months, the path length of the sun was shorter, with the sun rising north of east and setting north of west, hence, shorter day lengths. The solar radiation incident on a 25o north facing solar collector was found to be in three components; beam, diffuse and reflected. The beam component was higher in summer whereas the diffuse component was higher in winter due to an increase in the air mass ratio. However, the total daily average radiation was highest in January (7.12 peak sun hours) and least in June (3.04 peak sun hours). Finally, a comparison between the calculated and measured values of solar radiation showed just a 1.1percent difference over the year with disparities being in the individual months.m The influence of outdoor weather conditions on the performance of the system was also evaluated. Operating temperatures were noticed to have a great impact on the output voltage and power of the PV array. Significant correlations existed between various meteorological parameters. Also, a multiple linear regression model was developed to ascertain the dependence of module temperature on solar irradiance, ambient temperature, relative humidity, wind speed and wind direction. The coefficient of determination for the model was 0.928, showing a strong relationship between cell temperature and the chosen predictors. Also, the six thermocouples installed at various locations of the PV array revealed variations in the operating temperatures of the modules. The modules on the east side of the array recorded relatively lower temperatures because of the ceiling that had been removed beneath one of the modules on this side of the array, which permitted the free flow of air. Furthermore, I-V measurements conducted on various strings of the array revealed so many steps (hotspots), indicative of module (or cell) mismatch on almost all the cell strings.
- Full Text:
- Date Issued: 2018
- Authors: Buma, Carine Lethem
- Date: 2018
- Subjects: Building-integrated photovoltaic systems Buildings -- Energy conservation Performance -- Evaluation
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10353/13227 , vital:39623
- Description: The constant increase in the global demand for energy and the current crisis on global warming and climate change has prompted a dying quest for clean, sustainable and reliable sources of energy. Amongst numerous renewable energy technologies, harnessing energy from the sun is the most viable way of guaranteeing a clean and sustainable supply of energy. Also, photovoltaic energy is one of the ways of using energy from the sun, where sunlight is converted to electricity using photovoltaic panels. Furthermore, the integration of photovoltaic modules into buildings is one of the most elegant innovations of this technology, as it plays the dual role of supplying energy to the building as well as protecting the building from outdoor weather conditions. Moreover, operating off the grid offers the possibility of energy access to locations far off from the grid and individuals willing to gain some degree of energy independence. Evaluating the performance of existing off grid and/or building integrated photovoltaic systems is the key to guaranteeing sustainable development and advancement in the technology. Thus, the aim of this work was to evaluate the performance of an off-grid building integrated photovoltaic system that was installed at the Fort Hare Institute of Technology. This entailed performing an in-depth characterisation of the solar resource at this location, evaluating the performance of the modules under outdoor weather conditions and also evaluating the performance of the balance of system (BOS) components. The system was monitored for a period of nine months (between February and October 2017). A data acquisition system was designed for measuring and recording both electrical system parameters and meteorological parameters affecting the performance of the system. These meteorological parameters include; solar irradiance, ambient temperature, cell temperature, relative humidity, wind speed and direction. A detailed characterisation of the solar resource at this location was carried out. It was observed that the solar declination angle varied from -23.5o on the summer solstice to 23.5o on the winter solstice. Also, the solar altitude angle (at solar noon) which is a complementary angle to the zenith angle varied from 33.7o in June to 80.65o in December. During the summer months, longer day lengths were experienced because the sun traversed the sky over a longer time, rising south of east and setting south of west. Whereas, in the winter months, the path length of the sun was shorter, with the sun rising north of east and setting north of west, hence, shorter day lengths. The solar radiation incident on a 25o north facing solar collector was found to be in three components; beam, diffuse and reflected. The beam component was higher in summer whereas the diffuse component was higher in winter due to an increase in the air mass ratio. However, the total daily average radiation was highest in January (7.12 peak sun hours) and least in June (3.04 peak sun hours). Finally, a comparison between the calculated and measured values of solar radiation showed just a 1.1percent difference over the year with disparities being in the individual months.m The influence of outdoor weather conditions on the performance of the system was also evaluated. Operating temperatures were noticed to have a great impact on the output voltage and power of the PV array. Significant correlations existed between various meteorological parameters. Also, a multiple linear regression model was developed to ascertain the dependence of module temperature on solar irradiance, ambient temperature, relative humidity, wind speed and wind direction. The coefficient of determination for the model was 0.928, showing a strong relationship between cell temperature and the chosen predictors. Also, the six thermocouples installed at various locations of the PV array revealed variations in the operating temperatures of the modules. The modules on the east side of the array recorded relatively lower temperatures because of the ceiling that had been removed beneath one of the modules on this side of the array, which permitted the free flow of air. Furthermore, I-V measurements conducted on various strings of the array revealed so many steps (hotspots), indicative of module (or cell) mismatch on almost all the cell strings.
- Full Text:
- Date Issued: 2018
Performing the township: pantsula for life
- Van Niekerk, Heather Elizabeth
- Authors: Van Niekerk, Heather Elizabeth
- Date: 2018
- Subjects: Pantsula (Dance) South Africa Johannesburg , Pantsula (Dance) South Africa Makhanda , Dance Social aspects South Africa , Sophiatown (Johannesburg, South Africa)
- Language: English
- Type: text , Thesis , Masters , MA
- Identifier: http://hdl.handle.net/10962/57874 , vital:26998
- Description: Pantsula dance is a performing art born from the townships of Johannesburg. It is a dance form performed across South Africa, in a variety of contexts; in theatres, music videos and competitions in community halls, on national and international stages and on television, and in the streets of townships, cities and suburbs across South Africa and abroad. Its performance is widespread, but it has its beginnings as a dance form born in areas created to marginalise and oppress. There is a scarcity of academic scholarship related to pantsula dance. This thesis aims to be a contribution to that pre-existing body of knowledge in the hope that there can be further engagement on this important, and increasingly mainstream, art form. I have focused my thesis on analysing pantsula dance as a performance of 'the township'. This has been attempted through an ethnographic engagement with pantsula dancers based in different township areas of Johannesburg and Graha mstown: various members of Impilo Mapantsula, Via Katlehong, Intellectuals Pantsula, Via Kasi Movers, Dlala Majimboz and the cast of Via Katlehong's Via Sophiatown. The research was conducted between 2013 and 2016 and serves to represent various moments within the ethnographic research process, while coming to understand various aspects of pantsula dance. An engagement with notions of 'the township', the clothing choices of the pantsula 'uniform', the core moves, inherent hybridity in the form itself, and the dedication to the dance form as a representation of the isipantsula 'way of life', are addressed throughout the thesis. As well as engaging with the memory and representation of Sophiatown as an important component to pantsula dance. Pantsula dance, an intrinsically South African dance form, provides a celebratory conception of 'the township' space and allows people from different backgrounds to engage in an important part of South Africa's past, present and future.
- Full Text:
- Date Issued: 2018
- Authors: Van Niekerk, Heather Elizabeth
- Date: 2018
- Subjects: Pantsula (Dance) South Africa Johannesburg , Pantsula (Dance) South Africa Makhanda , Dance Social aspects South Africa , Sophiatown (Johannesburg, South Africa)
- Language: English
- Type: text , Thesis , Masters , MA
- Identifier: http://hdl.handle.net/10962/57874 , vital:26998
- Description: Pantsula dance is a performing art born from the townships of Johannesburg. It is a dance form performed across South Africa, in a variety of contexts; in theatres, music videos and competitions in community halls, on national and international stages and on television, and in the streets of townships, cities and suburbs across South Africa and abroad. Its performance is widespread, but it has its beginnings as a dance form born in areas created to marginalise and oppress. There is a scarcity of academic scholarship related to pantsula dance. This thesis aims to be a contribution to that pre-existing body of knowledge in the hope that there can be further engagement on this important, and increasingly mainstream, art form. I have focused my thesis on analysing pantsula dance as a performance of 'the township'. This has been attempted through an ethnographic engagement with pantsula dancers based in different township areas of Johannesburg and Graha mstown: various members of Impilo Mapantsula, Via Katlehong, Intellectuals Pantsula, Via Kasi Movers, Dlala Majimboz and the cast of Via Katlehong's Via Sophiatown. The research was conducted between 2013 and 2016 and serves to represent various moments within the ethnographic research process, while coming to understand various aspects of pantsula dance. An engagement with notions of 'the township', the clothing choices of the pantsula 'uniform', the core moves, inherent hybridity in the form itself, and the dedication to the dance form as a representation of the isipantsula 'way of life', are addressed throughout the thesis. As well as engaging with the memory and representation of Sophiatown as an important component to pantsula dance. Pantsula dance, an intrinsically South African dance form, provides a celebratory conception of 'the township' space and allows people from different backgrounds to engage in an important part of South Africa's past, present and future.
- Full Text:
- Date Issued: 2018
Periglacial landforms of the Ahlmannryggen and Jutulsessen areas of western Dronning Maud land, Antarctica
- Authors: Wilmot, Nicola Frances
- Date: 2018
- Subjects: Periglacial processes Antarctica Queen Maud Land , Geomorphology Antarctica Queen Maud Land , Permafrost Antarctica Queen Maud Land , Freezes (Meteorology) Antarctica Queen Maud Land , Thawing Antarctica Queen Maud Land
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/61535 , vital:28034
- Description: Periglacial landforms are a common occurrence in Ahlmannryggen and Jutulsessen areas of western Dronning Maud land (WDML). Classification and formation of these landforms were disputed in literature. In Antarctica information on periglacial landforms is limited or confined to a specific landform. Thus a holistic approach was taken when investigating the periglacial landforms found in WDML. An overview of the existing knowledge base on periglacial landforms in WDML was given which was coupled with the analysis of archival data. The landforms found in this area were patterned ground, openwork block deposits (OBD), rock glaciers, terraces, a pronival rampart and lake ice blisters. With patterned ground being the common periglacial landform in WDML, heave monitoring was used where time-lapse videos were used to investigate the formation processes in patterned ground. From consolidating existing knowledge as well as adding new knowledge on the formation of periglacial landforms, it is clear that the landforms in Antarctica should not be compared to other examples, especially examples from the northern hemisphere. Further research in the formation of periglacial landforms is needed and can be further enhanced with more extensive use of the heave monitoring method in future research.
- Full Text:
- Date Issued: 2018
- Authors: Wilmot, Nicola Frances
- Date: 2018
- Subjects: Periglacial processes Antarctica Queen Maud Land , Geomorphology Antarctica Queen Maud Land , Permafrost Antarctica Queen Maud Land , Freezes (Meteorology) Antarctica Queen Maud Land , Thawing Antarctica Queen Maud Land
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/61535 , vital:28034
- Description: Periglacial landforms are a common occurrence in Ahlmannryggen and Jutulsessen areas of western Dronning Maud land (WDML). Classification and formation of these landforms were disputed in literature. In Antarctica information on periglacial landforms is limited or confined to a specific landform. Thus a holistic approach was taken when investigating the periglacial landforms found in WDML. An overview of the existing knowledge base on periglacial landforms in WDML was given which was coupled with the analysis of archival data. The landforms found in this area were patterned ground, openwork block deposits (OBD), rock glaciers, terraces, a pronival rampart and lake ice blisters. With patterned ground being the common periglacial landform in WDML, heave monitoring was used where time-lapse videos were used to investigate the formation processes in patterned ground. From consolidating existing knowledge as well as adding new knowledge on the formation of periglacial landforms, it is clear that the landforms in Antarctica should not be compared to other examples, especially examples from the northern hemisphere. Further research in the formation of periglacial landforms is needed and can be further enhanced with more extensive use of the heave monitoring method in future research.
- Full Text:
- Date Issued: 2018
Perpetrators’ perspective of the psychological factors contributing to racially-motivated hate crimes in South Africa
- Authors: Heyneke, Wilmie
- Date: 2018
- Subjects: Hate crimes -- South Africa , Racism -- South Africa Violence -- South Africa
- Language: English
- Type: Thesis , Masters , MA
- Identifier: http://hdl.handle.net/10948/30072 , vital:30817
- Description: This study set out to explore and understand racially-motivated hate crimes from the psychological and emotional standpoint of the individual who perpetrated them. The focus on the perpetrator was essential given that most research conducted on hate crimes have honed in on the elements concerning the victims. By virtue of its focus, the study offered a perpetrator’s perspective, providing a more holistic understanding of hate crimes in South Africa. Such information could be used to develop violence interventions in order to help prevent future hate crimes. A qualitative research design was used and constructionist grounded theory employed as the research tool. The sample consisted of five individuals currently imprisoned in the Eastern Cape. Data was obtained through semi-structured interviews and journal entries. Supportive data was obtained from official prison documents. The findings from this study guided the formulation of the frustration deconstruction theory (FDT), the theory generated in this study. FDT indicates that the link between historically and socially constructed negative racial cognition and emotion may find expression through violence, which can be labelled as hate crimes. Interventions aimed at deconstructing the motives that underpin hate can result in positive behaviour. The findings of this study contribute to an understanding of the nuances that define and characterise the perpetrators of racially-motivated hate crimes in the South African context. The research is a valuable contribution to the field of hate crimes as it provides evidence of the psychological and emotional underpinning of hate crimes.
- Full Text:
- Date Issued: 2018
- Authors: Heyneke, Wilmie
- Date: 2018
- Subjects: Hate crimes -- South Africa , Racism -- South Africa Violence -- South Africa
- Language: English
- Type: Thesis , Masters , MA
- Identifier: http://hdl.handle.net/10948/30072 , vital:30817
- Description: This study set out to explore and understand racially-motivated hate crimes from the psychological and emotional standpoint of the individual who perpetrated them. The focus on the perpetrator was essential given that most research conducted on hate crimes have honed in on the elements concerning the victims. By virtue of its focus, the study offered a perpetrator’s perspective, providing a more holistic understanding of hate crimes in South Africa. Such information could be used to develop violence interventions in order to help prevent future hate crimes. A qualitative research design was used and constructionist grounded theory employed as the research tool. The sample consisted of five individuals currently imprisoned in the Eastern Cape. Data was obtained through semi-structured interviews and journal entries. Supportive data was obtained from official prison documents. The findings from this study guided the formulation of the frustration deconstruction theory (FDT), the theory generated in this study. FDT indicates that the link between historically and socially constructed negative racial cognition and emotion may find expression through violence, which can be labelled as hate crimes. Interventions aimed at deconstructing the motives that underpin hate can result in positive behaviour. The findings of this study contribute to an understanding of the nuances that define and characterise the perpetrators of racially-motivated hate crimes in the South African context. The research is a valuable contribution to the field of hate crimes as it provides evidence of the psychological and emotional underpinning of hate crimes.
- Full Text:
- Date Issued: 2018
Perspectives about the execution of police powers and functions in the republic of Zimbabwe
- Mugari, Ishmael, Obioha, Emeka, E
- Authors: Mugari, Ishmael , Obioha, Emeka, E
- Date: 2018
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/11260/4928 , vital:44304 , http://cjssp.uni-corvinus.hu/index.php/cjssp/article/view/220
- Description: This study was conducted to explore views about the execution of powers and functions of the police in the light of related challenges. This study made use of data from a total of 83 adult participants (a survey involving 73 individuals, and 10 in-depth interviews), including males and females of diverse occupational backgrounds from Bindura and Mount Darwin policing districts in Zimbabwe. A closed-ended, mostly Likert-scale-based questionnaire was used to collect data about the prevalent forms of police abuse of powers and functions, while an in-depth interview guide was provided to harvest information qualitatively. Findings reveal that police officers abuse their powers through unlawful arrests, arbitrary search and seizure, excessive use of force, unlawful methods of investigation, and ill treatment of detainees. Though not as prevalent as other forms of abuse, malicious criminal prosecution and partisan policing were also cited.K EYWOR DS: powers, abuse, function, police, Zimbabwe
- Full Text:
- Date Issued: 2018
- Authors: Mugari, Ishmael , Obioha, Emeka, E
- Date: 2018
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/11260/4928 , vital:44304 , http://cjssp.uni-corvinus.hu/index.php/cjssp/article/view/220
- Description: This study was conducted to explore views about the execution of powers and functions of the police in the light of related challenges. This study made use of data from a total of 83 adult participants (a survey involving 73 individuals, and 10 in-depth interviews), including males and females of diverse occupational backgrounds from Bindura and Mount Darwin policing districts in Zimbabwe. A closed-ended, mostly Likert-scale-based questionnaire was used to collect data about the prevalent forms of police abuse of powers and functions, while an in-depth interview guide was provided to harvest information qualitatively. Findings reveal that police officers abuse their powers through unlawful arrests, arbitrary search and seizure, excessive use of force, unlawful methods of investigation, and ill treatment of detainees. Though not as prevalent as other forms of abuse, malicious criminal prosecution and partisan policing were also cited.K EYWOR DS: powers, abuse, function, police, Zimbabwe
- Full Text:
- Date Issued: 2018
Petrophysical analysis of thermo-tectonic effects linked to Lower Jurassic dolerite intrusions in sedimentary rocks of the Main Karoo Basin, with implications for shale gas development in South Africa
- Authors: Nengovhela, Vhuhwavhohau
- Date: 2018
- Subjects: Sedimentary rocks -- South Africa -- Research , Sedimentation and deposition Geology, Structural -- South Africa Geology -- South Africa
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/33802 , vital:33034
- Description: Prevalent dolerite sills and dikes emplaced in the sedimentary rocks of the main Karoo Basin are associated with contact metamorphism and devolatilization of carbon-rich shales of the Lower Ecca Formation. These thermal effects may have significant bearings on the potential of shale gas development in the Karoo. This research aims to study and quantify the effects of dolerite intrusions on the Karoo sedimentary rocks along contact aureoles in shales and sandstones of the Ecca Group based on drill core samples collected from deep SOEKOR boreholes, and field samples from the Lower Beaufort Group of the Eastern Cape Province. Variations in host rock minerals, chemistry, and porosity are determined using analytical techniques including: petrography, scanning electron microscopy (SEM), X-ray diffraction (XRD) on samples collected along the thermal aureoles at various distances away from the intrusions. Using the determined mineral phase equilibria, geochemistry and thermal modelling, the pressure-temperature (P/T) conditions that prevailed during contact metamorphism are evaluated to constrain the thickness of the contact aureoles in deep boreholes, and to further evaluate potential loss of shale gas. The mineral composition of the samples generally consists of quartz, feldspar, illite/smectite, calcite, muscovite, and pyrite. Metamorphic minerals close to contacts with the sills include andalusite-chiastolite, biotite, muscovite, illite, forsterite, and diopside. SEM imaging confirms that the hornfels samples are compact and that the metamorphic minerals reduce and limit porosity to grain boundaries, and in few cases intra-mineral porosity occurs within individual crystals. The porosities are in the range of mesopores (2-50 nm) and micropores (< 2 nm). The data also suggests that the thermal alteration of the Ecca shales were short lived (e.g. 10-100 years). Disequilibrium metamorphic textures such as irregular grain boundaries, and inclusions in andalusite and cordierite confirm that the elevated temperatures did not last long enough to accomplish (re)crystallization and create equilibrium textures. To test the effect of geothermal gradients on the initial host rock temperatures prior to intrusive activity, and how these temperature differences affect the contact aureole thickness, thermal models were simulated for the deep boreholes using three geothermal gradients: 30 ◦C/km, 35 ◦C/km, and 40 ◦C/km. In addition, the depths were re-calculated based on post-emplacement erosion of the overlying host rocks (2000-3000 m). Heat flow away from dolerite sills through the host shales were modelled using convection and conduction heat flow mechanism separately, to assess differences and/or similarities in cooling trends. The models show that a 10 ◦C increase in geothermal gradient (from 30 ◦C /km to 40 ◦C/km) significantly affects the initial temperature of the host rocks and in turn decreases the rate at which the dolerite sills cool. Thermal modeling data is coherent with the mineralogy of the contact zones. Andalusitechiastolite and cordierite porphyroblasts occur within 10-20 m of the contact aureole, together with biotite and authigenic muscovite. Literature data shows that crystallization of this mineral assemblage in pelitic hornfels occurs at temperatures ranging between 450 ◦C and 600 ◦C. Thermal modelling results indicate maximum temperatures of shales at the contact with dolerite sills range between 650 ◦C to 700 ◦C. Temperatures decrease rapidly to approximately 400 ◦C within 10-20 m away from the contacts. The data also shows that thermal perturbation flanking the sills were short-lived, with maximum temperatures reached within the first 100 years of cooling depending on the thickness of dolerite sills and the combined effect of multiple sill intrusions. Data acquired from the thermal models and literature was used to evaluate gas loss estimations. The calculations conducted around a 45 m thick sill, suggests that at least 4- 6 TCF of gas was liberated from the Whitehill Formation during Karoo sill emplacement. These values are significantly less than previously calculated losses (22 TCF), and thus have a significant bearing on further predictions of shale gas potential of the Karoo Basin.
- Full Text:
- Date Issued: 2018
- Authors: Nengovhela, Vhuhwavhohau
- Date: 2018
- Subjects: Sedimentary rocks -- South Africa -- Research , Sedimentation and deposition Geology, Structural -- South Africa Geology -- South Africa
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/33802 , vital:33034
- Description: Prevalent dolerite sills and dikes emplaced in the sedimentary rocks of the main Karoo Basin are associated with contact metamorphism and devolatilization of carbon-rich shales of the Lower Ecca Formation. These thermal effects may have significant bearings on the potential of shale gas development in the Karoo. This research aims to study and quantify the effects of dolerite intrusions on the Karoo sedimentary rocks along contact aureoles in shales and sandstones of the Ecca Group based on drill core samples collected from deep SOEKOR boreholes, and field samples from the Lower Beaufort Group of the Eastern Cape Province. Variations in host rock minerals, chemistry, and porosity are determined using analytical techniques including: petrography, scanning electron microscopy (SEM), X-ray diffraction (XRD) on samples collected along the thermal aureoles at various distances away from the intrusions. Using the determined mineral phase equilibria, geochemistry and thermal modelling, the pressure-temperature (P/T) conditions that prevailed during contact metamorphism are evaluated to constrain the thickness of the contact aureoles in deep boreholes, and to further evaluate potential loss of shale gas. The mineral composition of the samples generally consists of quartz, feldspar, illite/smectite, calcite, muscovite, and pyrite. Metamorphic minerals close to contacts with the sills include andalusite-chiastolite, biotite, muscovite, illite, forsterite, and diopside. SEM imaging confirms that the hornfels samples are compact and that the metamorphic minerals reduce and limit porosity to grain boundaries, and in few cases intra-mineral porosity occurs within individual crystals. The porosities are in the range of mesopores (2-50 nm) and micropores (< 2 nm). The data also suggests that the thermal alteration of the Ecca shales were short lived (e.g. 10-100 years). Disequilibrium metamorphic textures such as irregular grain boundaries, and inclusions in andalusite and cordierite confirm that the elevated temperatures did not last long enough to accomplish (re)crystallization and create equilibrium textures. To test the effect of geothermal gradients on the initial host rock temperatures prior to intrusive activity, and how these temperature differences affect the contact aureole thickness, thermal models were simulated for the deep boreholes using three geothermal gradients: 30 ◦C/km, 35 ◦C/km, and 40 ◦C/km. In addition, the depths were re-calculated based on post-emplacement erosion of the overlying host rocks (2000-3000 m). Heat flow away from dolerite sills through the host shales were modelled using convection and conduction heat flow mechanism separately, to assess differences and/or similarities in cooling trends. The models show that a 10 ◦C increase in geothermal gradient (from 30 ◦C /km to 40 ◦C/km) significantly affects the initial temperature of the host rocks and in turn decreases the rate at which the dolerite sills cool. Thermal modeling data is coherent with the mineralogy of the contact zones. Andalusitechiastolite and cordierite porphyroblasts occur within 10-20 m of the contact aureole, together with biotite and authigenic muscovite. Literature data shows that crystallization of this mineral assemblage in pelitic hornfels occurs at temperatures ranging between 450 ◦C and 600 ◦C. Thermal modelling results indicate maximum temperatures of shales at the contact with dolerite sills range between 650 ◦C to 700 ◦C. Temperatures decrease rapidly to approximately 400 ◦C within 10-20 m away from the contacts. The data also shows that thermal perturbation flanking the sills were short-lived, with maximum temperatures reached within the first 100 years of cooling depending on the thickness of dolerite sills and the combined effect of multiple sill intrusions. Data acquired from the thermal models and literature was used to evaluate gas loss estimations. The calculations conducted around a 45 m thick sill, suggests that at least 4- 6 TCF of gas was liberated from the Whitehill Formation during Karoo sill emplacement. These values are significantly less than previously calculated losses (22 TCF), and thus have a significant bearing on further predictions of shale gas potential of the Karoo Basin.
- Full Text:
- Date Issued: 2018
pH-Dependent release of isoniazid from isonicotinic acid (4-hydroxy-benzylidene)-hydrazide loaded liposomes
- Nkanga, Christian I, Tor-Anyiin, Terrumun A, Igoli, John O, Noundou, Xavier S, Krause, Rui W M
- Authors: Nkanga, Christian I , Tor-Anyiin, Terrumun A , Igoli, John O , Noundou, Xavier S , Krause, Rui W M
- Date: 2018
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/126427 , vital:35884 , https://doi.org/10.9734/AJOCS/2017/37147
- Description: Liposomes are considered as potential vehicles for the delivery of anti-tuberculosis drugs (ATBD) due to their rapid uptake by alveolar macrophages, where the mycobacterium often resides. This may provide macrophage-targeting effects that would be key to site specific ATBD delivery using pH-sensitive liposomes, considering the pH-gradient found in the phagocytotic pathway. In this study, isoniazid (INH) was conjugated to 4-hydroxy-benzaldehyde via a hydrazone bond to yield isonicotinic acid (4-hydroxy-benzylidene)-hydrazide (INH-HB). This conjugate was encapsulated in crude soybean lecithin liposomes using film hydration method. INH-HB loaded liposomes (IHL) were characterized by means of dynamic light scattering, transmission electron microscopy, differential scanning calorimetry and X-ray diffraction. The release of INH from IHL was evaluated in media of different pH using a dialysis method. The particle size, Zeta Potential and encapsulation efficiency of IHL were about 945 nm, −62 mV and 89% respectively. In media of pH 7.4, 6.4, 5.4 and 4.4; the IHL exhibited respectively 22, 69, 83 and 100% of release over 12 h. In addition to possible targeted delivery, this pH-dependent release behavior may be suitable for minimizing the loss of INH by leakage from liposomes. The characteristics of IHL are promising for potential site-specific delivery of ATBD.
- Full Text:
- Date Issued: 2018
- Authors: Nkanga, Christian I , Tor-Anyiin, Terrumun A , Igoli, John O , Noundou, Xavier S , Krause, Rui W M
- Date: 2018
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/126427 , vital:35884 , https://doi.org/10.9734/AJOCS/2017/37147
- Description: Liposomes are considered as potential vehicles for the delivery of anti-tuberculosis drugs (ATBD) due to their rapid uptake by alveolar macrophages, where the mycobacterium often resides. This may provide macrophage-targeting effects that would be key to site specific ATBD delivery using pH-sensitive liposomes, considering the pH-gradient found in the phagocytotic pathway. In this study, isoniazid (INH) was conjugated to 4-hydroxy-benzaldehyde via a hydrazone bond to yield isonicotinic acid (4-hydroxy-benzylidene)-hydrazide (INH-HB). This conjugate was encapsulated in crude soybean lecithin liposomes using film hydration method. INH-HB loaded liposomes (IHL) were characterized by means of dynamic light scattering, transmission electron microscopy, differential scanning calorimetry and X-ray diffraction. The release of INH from IHL was evaluated in media of different pH using a dialysis method. The particle size, Zeta Potential and encapsulation efficiency of IHL were about 945 nm, −62 mV and 89% respectively. In media of pH 7.4, 6.4, 5.4 and 4.4; the IHL exhibited respectively 22, 69, 83 and 100% of release over 12 h. In addition to possible targeted delivery, this pH-dependent release behavior may be suitable for minimizing the loss of INH by leakage from liposomes. The characteristics of IHL are promising for potential site-specific delivery of ATBD.
- Full Text:
- Date Issued: 2018
Pharmacist perceptions of pharmacy support personnel in the pharmaceutical manufacturing sector in Port Elizabeth
- Authors: Worthington, Nicole
- Date: 2018
- Subjects: Pharmacists -- South Africa -- Port Elizabeth
- Language: English
- Type: Thesis , Masters , MPharm
- Identifier: http://hdl.handle.net/10948/42434 , vital:36659
- Description: Pharmacy support personnel (PSP) are employed across multiple pharmaceutical sectors in South Africa. They assist pharmacists in the manufacturing sector, while under their direct, personal supervision, to carry out the pharmacists’ functions listed in the South African Good Manufacturing Practice guidelines, within a defined scope of practice. Prior to 2013, all PSP training was workplace-based. The recent introduction of a university-based qualification for PSP has resulted in two routes for students to qualify as PSP. This study employed a qualitative, phenomenological design using semistructured interviews with pharmacists employed in pharmaceutical manufacturing. Their perceptions regarding PSP who had trained via the two training routes where interpreted through thematic analysis in order to determine whether a perceived difference in the abilities of the two cadres of PSP exists. Pharmacists generally expressed a more positive perception of PSP who qualified through the university-based programme. Strengths and weaknesses of both routes of training were identified, with areas of possible improvement identified for both programmes. Furthermore, a mutually supportive pharmacist – PSP relationship was deemed important in order to achieve optimal functionality in the workplace. The need for both pharmacists and PSP to be made aware of the roles that they play in this relationship was highlighted.
- Full Text:
- Date Issued: 2018
- Authors: Worthington, Nicole
- Date: 2018
- Subjects: Pharmacists -- South Africa -- Port Elizabeth
- Language: English
- Type: Thesis , Masters , MPharm
- Identifier: http://hdl.handle.net/10948/42434 , vital:36659
- Description: Pharmacy support personnel (PSP) are employed across multiple pharmaceutical sectors in South Africa. They assist pharmacists in the manufacturing sector, while under their direct, personal supervision, to carry out the pharmacists’ functions listed in the South African Good Manufacturing Practice guidelines, within a defined scope of practice. Prior to 2013, all PSP training was workplace-based. The recent introduction of a university-based qualification for PSP has resulted in two routes for students to qualify as PSP. This study employed a qualitative, phenomenological design using semistructured interviews with pharmacists employed in pharmaceutical manufacturing. Their perceptions regarding PSP who had trained via the two training routes where interpreted through thematic analysis in order to determine whether a perceived difference in the abilities of the two cadres of PSP exists. Pharmacists generally expressed a more positive perception of PSP who qualified through the university-based programme. Strengths and weaknesses of both routes of training were identified, with areas of possible improvement identified for both programmes. Furthermore, a mutually supportive pharmacist – PSP relationship was deemed important in order to achieve optimal functionality in the workplace. The need for both pharmacists and PSP to be made aware of the roles that they play in this relationship was highlighted.
- Full Text:
- Date Issued: 2018
PhD graduates' perceptions of supervision contact sessions at the University of Fort Hare, Eastern Cape, South Africa
- Authors: Muleya, Ekem
- Date: 2018
- Subjects: University of Fort Hare Graduate students Doctoral students
- Language: English
- Type: Thesis , Masters , MSoc
- Identifier: http://hdl.handle.net/10353/12914 , vital:39401
- Description: PhD supervision is mostly studied from the supervisor and education institutions’ point of view in South Africa. The role and what exactly transpires during supervision contact sessions, how it influences or contributes to the successful completion of a PhD degree has been under researched. The government of South Africa through the NDP has clear targets in terms of raising the annual number of people who graduate with PhDs, however the processes and the actual ingredients contributing to the increase are not being adequately examined. The purpose of this study was to investigate the contribution of supervision contact sessions in enabling a doctoral candidate to successfully complete a doctoral degree. Specifically this study sought to find out how supervision meetings enable a PhD candidate to finish the PhD degree successfully. This exploratory study sought to address the question through pin-pointing the specific benefits PhD candidates derive from supervision contact sessions and at the same time documenting the challenges faced in these meetings. Findings from this study point to the fact that supervision contact sessions are crucial in empowering a PhD candidate to finish his or her studies. Candidates benefit from both technical (professional) and social (emotional) support through supervision meetings with their supervisors and most importantly supervisors also assist and advise their candidates with regard to funding for their studies. In the main, PhD candidates prefer to meet frequently with their supervisors to discuss their PhD work however they in some instances encounter challenges in trying to set up meetings with their supervisors. Challenges also come during the actual supervision sessions due to the unequal relationship between supervisor and candidate. Given the role of supervision meetings in PhD completion, it is important to note some measures which can assist in terms of making supervision meetings more beneficial to a PhD candidate.
- Full Text:
- Date Issued: 2018
- Authors: Muleya, Ekem
- Date: 2018
- Subjects: University of Fort Hare Graduate students Doctoral students
- Language: English
- Type: Thesis , Masters , MSoc
- Identifier: http://hdl.handle.net/10353/12914 , vital:39401
- Description: PhD supervision is mostly studied from the supervisor and education institutions’ point of view in South Africa. The role and what exactly transpires during supervision contact sessions, how it influences or contributes to the successful completion of a PhD degree has been under researched. The government of South Africa through the NDP has clear targets in terms of raising the annual number of people who graduate with PhDs, however the processes and the actual ingredients contributing to the increase are not being adequately examined. The purpose of this study was to investigate the contribution of supervision contact sessions in enabling a doctoral candidate to successfully complete a doctoral degree. Specifically this study sought to find out how supervision meetings enable a PhD candidate to finish the PhD degree successfully. This exploratory study sought to address the question through pin-pointing the specific benefits PhD candidates derive from supervision contact sessions and at the same time documenting the challenges faced in these meetings. Findings from this study point to the fact that supervision contact sessions are crucial in empowering a PhD candidate to finish his or her studies. Candidates benefit from both technical (professional) and social (emotional) support through supervision meetings with their supervisors and most importantly supervisors also assist and advise their candidates with regard to funding for their studies. In the main, PhD candidates prefer to meet frequently with their supervisors to discuss their PhD work however they in some instances encounter challenges in trying to set up meetings with their supervisors. Challenges also come during the actual supervision sessions due to the unequal relationship between supervisor and candidate. Given the role of supervision meetings in PhD completion, it is important to note some measures which can assist in terms of making supervision meetings more beneficial to a PhD candidate.
- Full Text:
- Date Issued: 2018
Photo-induced resonance energy transfer and nonlinear optical response in ball-type phthalocyanine conjugated to semiconductor and graphene quantum dots
- Nwaji, Njemuwa, Achadu, Ojodomo John, Nyokong, Tebello
- Authors: Nwaji, Njemuwa , Achadu, Ojodomo John , Nyokong, Tebello
- Date: 2018
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/187959 , vital:44713 , xlink:href="https://doi.org/10.1039/C7NJ05196D"
- Description: The synthesis of ball-type zinc and gallium phthalocyanines (complexes 2 and 3) and their covalent linkage to glutathione (GSH) and amine functionalized quantum dots QDs) are reported in this work. Furthermore, their photophysical, photo-induced resonance energy transfer and optical limiting responses were investigated. We observed a decrease in the fluorescence quantum yields with a corresponding increase in the triplet quantum yields of the nanoconjugates in comparison to the phthalocyanine complexes alone. The reverse saturable absorption was found to be dependent on the excited state absorption, and the observed limiting threshold ranged from 0.32 to 1.43 J cm−2. Enhanced triplet parameters and nonlinear optical performance were found when the complexes were covalently linked to semiconductor quantum dots compared to carbon based graphene quantum dots.
- Full Text:
- Date Issued: 2018
- Authors: Nwaji, Njemuwa , Achadu, Ojodomo John , Nyokong, Tebello
- Date: 2018
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/187959 , vital:44713 , xlink:href="https://doi.org/10.1039/C7NJ05196D"
- Description: The synthesis of ball-type zinc and gallium phthalocyanines (complexes 2 and 3) and their covalent linkage to glutathione (GSH) and amine functionalized quantum dots QDs) are reported in this work. Furthermore, their photophysical, photo-induced resonance energy transfer and optical limiting responses were investigated. We observed a decrease in the fluorescence quantum yields with a corresponding increase in the triplet quantum yields of the nanoconjugates in comparison to the phthalocyanine complexes alone. The reverse saturable absorption was found to be dependent on the excited state absorption, and the observed limiting threshold ranged from 0.32 to 1.43 J cm−2. Enhanced triplet parameters and nonlinear optical performance were found when the complexes were covalently linked to semiconductor quantum dots compared to carbon based graphene quantum dots.
- Full Text:
- Date Issued: 2018
Photodynamic therapy activity of zinc phthalocyanine linked to folic acid and magnetic nanoparticles
- Matlou, Gauta G, Oluwole, David O, Prinsloo, Earl, Nyokong, Tebello
- Authors: Matlou, Gauta G , Oluwole, David O , Prinsloo, Earl , Nyokong, Tebello
- Date: 2018
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/234429 , vital:50195 , xlink:href="https://doi.org/10.1016/j.jphotobiol.2018.07.025"
- Description: In this work, the photodynamic therapy (PDT) activities (using human carcinoma adherent MCF-7 cells) of zinc phthalocyanine derivatives: complexes 1 (Zn mono cinnamic acid phthalocyanine) and 2 (zinc mono carboxyphenoxy phthalocyanine) when covalently linked to folic acid (FA) and amine functionalized magnetic nanoparticles (AMNPs) are reported. The covalent linkage of asymmetric zinc cinnamic acid Pc (1) to FA (1-FA) through an amide bond is reported for the first time. Complex 1 is insoluble in water, but upon linkage to FA, (to form 1-FA) the molecule become water soluble, hence the UV–Vis spectrum and singlet oxygen quantum yield for 1-FA were also done in water since water solubility is essential for biological applications. The reported 2-FA is also water soluble. Linking complexes 1 and 2 to FA and AMNPs decreased the dark toxicity of 1 and 2 on MCF-7 cells. Pc-FA (1-FA and 2-FA) conjugates had better singlet oxygen quantum yields (Φ∆) in DMSO as compared to Pc-AMNPs (1-AMNPs and 2-AMNPs). The water- soluble 1-FA and 2-FA also achieved a better photodynamic therapy (PDT) activity as compared to 1-AMNPs and 2-AMNPs. Folic acid targeting on the tumor cells may have also facilitated better bioavailability of 1-FA and 2-FA and improved PDT activity on MCF-7 cells over AMNPs carriers.
- Full Text:
- Date Issued: 2018
Photodynamic therapy activity of zinc phthalocyanine linked to folic acid and magnetic nanoparticles
- Authors: Matlou, Gauta G , Oluwole, David O , Prinsloo, Earl , Nyokong, Tebello
- Date: 2018
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/234429 , vital:50195 , xlink:href="https://doi.org/10.1016/j.jphotobiol.2018.07.025"
- Description: In this work, the photodynamic therapy (PDT) activities (using human carcinoma adherent MCF-7 cells) of zinc phthalocyanine derivatives: complexes 1 (Zn mono cinnamic acid phthalocyanine) and 2 (zinc mono carboxyphenoxy phthalocyanine) when covalently linked to folic acid (FA) and amine functionalized magnetic nanoparticles (AMNPs) are reported. The covalent linkage of asymmetric zinc cinnamic acid Pc (1) to FA (1-FA) through an amide bond is reported for the first time. Complex 1 is insoluble in water, but upon linkage to FA, (to form 1-FA) the molecule become water soluble, hence the UV–Vis spectrum and singlet oxygen quantum yield for 1-FA were also done in water since water solubility is essential for biological applications. The reported 2-FA is also water soluble. Linking complexes 1 and 2 to FA and AMNPs decreased the dark toxicity of 1 and 2 on MCF-7 cells. Pc-FA (1-FA and 2-FA) conjugates had better singlet oxygen quantum yields (Φ∆) in DMSO as compared to Pc-AMNPs (1-AMNPs and 2-AMNPs). The water- soluble 1-FA and 2-FA also achieved a better photodynamic therapy (PDT) activity as compared to 1-AMNPs and 2-AMNPs. Folic acid targeting on the tumor cells may have also facilitated better bioavailability of 1-FA and 2-FA and improved PDT activity on MCF-7 cells over AMNPs carriers.
- Full Text:
- Date Issued: 2018
Photoluminescence and thermoluminescence properties of BaGa2O4
- Noto, L L, Poelman, D, Orante-Barrón, V R, Swart, H C, Mathevula, Langutani E, Nyenge, R, Chithambo, Makaiko L, Mothudi, B M, Dhlamini, M S
- Authors: Noto, L L , Poelman, D , Orante-Barrón, V R , Swart, H C , Mathevula, Langutani E , Nyenge, R , Chithambo, Makaiko L , Mothudi, B M , Dhlamini, M S
- Date: 2018
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/116037 , vital:34292 , https://doi.org/10.1016/j.physb.2017.07.059
- Description: Rare–Earth free luminescent materials are fast becoming important as the cost of rare earth ions gradually increases. In this work, a Rare–Earth free BaGa2O4 luminescent compound was prepared by solid state chemical reaction, which was confirmed to have a single phase by X-ray Diffraction. The Backscattered Electron image and Energy Dispersive X-ray spectroscopy maps confirmed irregular particle and homogeneous compound formation, respectively. The Photoluminescence spectrum displayed broad emission between 350 to 650 nm, which was deconvoluted into two components. The photoluminescence excitation peak was positioned at 254 nm, which corresponds with the band-to-band position observed from the diffuse reflectance spectrum. The band gap was extrapolated to 4.65 ± 0.02 eV using the Kubelka-Munk model. The preliminary thermoluminescence results indicated that the kinetics involved were neither of first nor second order. Additionally, the activation energy of the electrons within the trap centres was approximated to 0.61 ± 0.01 eV using the Initial Rise model.
- Full Text: false
- Date Issued: 2018
- Authors: Noto, L L , Poelman, D , Orante-Barrón, V R , Swart, H C , Mathevula, Langutani E , Nyenge, R , Chithambo, Makaiko L , Mothudi, B M , Dhlamini, M S
- Date: 2018
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/116037 , vital:34292 , https://doi.org/10.1016/j.physb.2017.07.059
- Description: Rare–Earth free luminescent materials are fast becoming important as the cost of rare earth ions gradually increases. In this work, a Rare–Earth free BaGa2O4 luminescent compound was prepared by solid state chemical reaction, which was confirmed to have a single phase by X-ray Diffraction. The Backscattered Electron image and Energy Dispersive X-ray spectroscopy maps confirmed irregular particle and homogeneous compound formation, respectively. The Photoluminescence spectrum displayed broad emission between 350 to 650 nm, which was deconvoluted into two components. The photoluminescence excitation peak was positioned at 254 nm, which corresponds with the band-to-band position observed from the diffuse reflectance spectrum. The band gap was extrapolated to 4.65 ± 0.02 eV using the Kubelka-Munk model. The preliminary thermoluminescence results indicated that the kinetics involved were neither of first nor second order. Additionally, the activation energy of the electrons within the trap centres was approximated to 0.61 ± 0.01 eV using the Initial Rise model.
- Full Text: false
- Date Issued: 2018
Photophysical and strong optical limiting properties of ball-type phthalocyanines dimers and their monomeric analogues
- Nwaji, Njemuwa, Mack, John, Nyokong, Tebello
- Authors: Nwaji, Njemuwa , Mack, John , Nyokong, Tebello
- Date: 2018
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/187930 , vital:44711 , xlink:href="https://doi.org/10.1016/j.jphotochem.2017.10.045"
- Description: The nonlinear optical behaviors of ball-type phthalocyanine complexes: 1′,11,’15′,25′-tetrakis-[4,4′-((4-formyl-1,2-bisphenoxyl))bis(phthalocyaninato zinc (II)] (5), 1′,11,’15′,25′-tetrakis-[4,4′-((4-formyl-1,2-bisphenoxyl) bis(phthalocyaninato gallium (III) chloride)] (6), and 1′, 11,’15′,25′-tetrakis-4,4′-((4-formyl-1,2-phenoxyl)bis(phthalocyaninato indium (III) chloride)] (7) and the corresponding monomeric derivatives 8–10 were investigated using nanosecond pulse open aperture Z-scan technique at 532 nm. The nonlinear response showed strong reverse saturable absorption for all the complexes both in solution and when embedded in polymer matrix. The dimeric complexes showed better optical limiting properties compared to the monomeric derivatives. The βeff values for the dimeric complexes 5–7 were found to be 48.5, 55.2, and 60.1 cm/GW for 5, 6A, and 7 respectively, higher than the corresponding monomeric derivatives 8–10. Enhanced optical limiting properties were observed when the complexes were formulated in thin films. The second order hyperpolarizability values were in order of 10−28–10−26 esu in solution and 10−27–10−26 in films.
- Full Text:
- Date Issued: 2018
- Authors: Nwaji, Njemuwa , Mack, John , Nyokong, Tebello
- Date: 2018
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/187930 , vital:44711 , xlink:href="https://doi.org/10.1016/j.jphotochem.2017.10.045"
- Description: The nonlinear optical behaviors of ball-type phthalocyanine complexes: 1′,11,’15′,25′-tetrakis-[4,4′-((4-formyl-1,2-bisphenoxyl))bis(phthalocyaninato zinc (II)] (5), 1′,11,’15′,25′-tetrakis-[4,4′-((4-formyl-1,2-bisphenoxyl) bis(phthalocyaninato gallium (III) chloride)] (6), and 1′, 11,’15′,25′-tetrakis-4,4′-((4-formyl-1,2-phenoxyl)bis(phthalocyaninato indium (III) chloride)] (7) and the corresponding monomeric derivatives 8–10 were investigated using nanosecond pulse open aperture Z-scan technique at 532 nm. The nonlinear response showed strong reverse saturable absorption for all the complexes both in solution and when embedded in polymer matrix. The dimeric complexes showed better optical limiting properties compared to the monomeric derivatives. The βeff values for the dimeric complexes 5–7 were found to be 48.5, 55.2, and 60.1 cm/GW for 5, 6A, and 7 respectively, higher than the corresponding monomeric derivatives 8–10. Enhanced optical limiting properties were observed when the complexes were formulated in thin films. The second order hyperpolarizability values were in order of 10−28–10−26 esu in solution and 10−27–10−26 in films.
- Full Text:
- Date Issued: 2018
Photophysical properties of a novel styryl-BODIPY with a fused crown ether moiety
- Stone, Justin, Mack, John, Nyokong, Tebello, Kimura, Mitsumi, Kobayashi, Nagao
- Authors: Stone, Justin , Mack, John , Nyokong, Tebello , Kimura, Mitsumi , Kobayashi, Nagao
- Date: 2018
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/188227 , vital:44736 , xlink:href="https://doi.org/10.1142/S1088424617500699"
- Description: The synthesis and characterization of a crown-ether-substituted 3-styrylBODIPY dye with a 4-isopropylphenyl group at the meso-position is reported. The effect that the incorporation of Na++ ions into the crown ether moiety has on the photophysical properties is investigated.
- Full Text:
- Date Issued: 2018
- Authors: Stone, Justin , Mack, John , Nyokong, Tebello , Kimura, Mitsumi , Kobayashi, Nagao
- Date: 2018
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/188227 , vital:44736 , xlink:href="https://doi.org/10.1142/S1088424617500699"
- Description: The synthesis and characterization of a crown-ether-substituted 3-styrylBODIPY dye with a 4-isopropylphenyl group at the meso-position is reported. The effect that the incorporation of Na++ ions into the crown ether moiety has on the photophysical properties is investigated.
- Full Text:
- Date Issued: 2018
Photophysical studies of graphene quantum dots-Pyrene-derivatized porphyrins conjugates when encapsulated within Pluronic F127 micelles
- Managa, Muthumuni, Achadu, Ojodomo John, Nyokong, Tebello
- Authors: Managa, Muthumuni , Achadu, Ojodomo John , Nyokong, Tebello
- Date: 2018
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/187971 , vital:44714 , xlink:href="https://doi.org/10.1016/j.dyepig.2017.09.031"
- Description: Pyrene-derivatized H2, GaCl, and Zn porphyrins were immobilized on graphene quantum dots (GQDs) to form (GQDs-H2TPrP, GQDs-GaClTPrP, and GQDs-ZnTPrP) conjugates through the π-π stacking interaction method followed by encapsulating into Pluronic F127 micelles to form (GQDs-H2TPrP + F127, GQDs-GaClTPrP + F127, and GQDs-ZnTPrP + F127). Spectroscopic evidence shows that the resultant conjugates were stable due to the strong π-π stacking interaction between the GQDs and the porphyrins. The fluorescence and singlet oxygen generating behaviour of the porphyrins were investigated following incorporation. GQDs-GaClTPrP + F127 showed highest values of the binding constant (Kb). The Stern-Volmer constant (Ksv) for GQDs-ZnTPrP + F127 were the highest compared to other porphyrins derivatives.
- Full Text:
- Date Issued: 2018
- Authors: Managa, Muthumuni , Achadu, Ojodomo John , Nyokong, Tebello
- Date: 2018
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/187971 , vital:44714 , xlink:href="https://doi.org/10.1016/j.dyepig.2017.09.031"
- Description: Pyrene-derivatized H2, GaCl, and Zn porphyrins were immobilized on graphene quantum dots (GQDs) to form (GQDs-H2TPrP, GQDs-GaClTPrP, and GQDs-ZnTPrP) conjugates through the π-π stacking interaction method followed by encapsulating into Pluronic F127 micelles to form (GQDs-H2TPrP + F127, GQDs-GaClTPrP + F127, and GQDs-ZnTPrP + F127). Spectroscopic evidence shows that the resultant conjugates were stable due to the strong π-π stacking interaction between the GQDs and the porphyrins. The fluorescence and singlet oxygen generating behaviour of the porphyrins were investigated following incorporation. GQDs-GaClTPrP + F127 showed highest values of the binding constant (Kb). The Stern-Volmer constant (Ksv) for GQDs-ZnTPrP + F127 were the highest compared to other porphyrins derivatives.
- Full Text:
- Date Issued: 2018
Photophysicochemical behaviour and antimicrobial properties of monocarboxy Mg (II) and Al (III) phthalocyanine-magnetite conjugates
- Idowu, Mopelola A I, Xego, Solami, Arslanoglu, Yasin, Mark, John, Antunes, Edith M, Nyokong, Tebello
- Authors: Idowu, Mopelola A I , Xego, Solami , Arslanoglu, Yasin , Mark, John , Antunes, Edith M , Nyokong, Tebello
- Date: 2018
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/188205 , vital:44734 , xlink:href="https://doi.org/10.1016/j.saa.2017.12.052"
- Description: Asymmetric Mg (II) or Al (III) phthalocyanine (containing a COOH group and 3-pyridylsulfanyl units) was conjugated via an amide bond to amino functionalized magnetic nanoparticle (AIMN) to form MgPc-AIMN or AlPc-AIMN conjugate, and characterized. The photophysicochemical behaviour of the phthalocyanine–AIMN conjugates was investigated and compared to the asymmetric Pcs and to the simple mixture of Pc with AIMNs without a chemical bond, (MPc-AIMN (mixed)). The directed covalent linkage of AIMNs to the asymmetrical metallopthalocyanines afforded improvements in the singlet oxygen (ФΔ) and triplet state quantum yield (ФT) as well as singlet oxygen lifetimes for the MPcs–AIMN-linked conjugates compared to MPc-AIMN (mixed) and MPcs alone. The asymmetric phthalocyanines and their conjugates showed effective antimicrobial activity against Escherichia coli bacteria under illumination.
- Full Text:
- Date Issued: 2018
- Authors: Idowu, Mopelola A I , Xego, Solami , Arslanoglu, Yasin , Mark, John , Antunes, Edith M , Nyokong, Tebello
- Date: 2018
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/188205 , vital:44734 , xlink:href="https://doi.org/10.1016/j.saa.2017.12.052"
- Description: Asymmetric Mg (II) or Al (III) phthalocyanine (containing a COOH group and 3-pyridylsulfanyl units) was conjugated via an amide bond to amino functionalized magnetic nanoparticle (AIMN) to form MgPc-AIMN or AlPc-AIMN conjugate, and characterized. The photophysicochemical behaviour of the phthalocyanine–AIMN conjugates was investigated and compared to the asymmetric Pcs and to the simple mixture of Pc with AIMNs without a chemical bond, (MPc-AIMN (mixed)). The directed covalent linkage of AIMNs to the asymmetrical metallopthalocyanines afforded improvements in the singlet oxygen (ФΔ) and triplet state quantum yield (ФT) as well as singlet oxygen lifetimes for the MPcs–AIMN-linked conjugates compared to MPc-AIMN (mixed) and MPcs alone. The asymmetric phthalocyanines and their conjugates showed effective antimicrobial activity against Escherichia coli bacteria under illumination.
- Full Text:
- Date Issued: 2018
Photophysicochemical properties and photodynamic therapy activity of highly water-soluble Zn (II) phthalocyanines
- Oluwole, David O, Sari, Fatma Aslihan, Prinsloo, Earl, Dube, Edith, Yuzer, Abdulcelil, Nyokong, Tebello, Ince, Mine
- Authors: Oluwole, David O , Sari, Fatma Aslihan , Prinsloo, Earl , Dube, Edith , Yuzer, Abdulcelil , Nyokong, Tebello , Ince, Mine
- Date: 2018
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/234507 , vital:50203 , xlink:href="https://doi.org/10.1016/j.saa.2018.05.090"
- Description: The syntheses of two zinc(II) phthalocyanines (ZnPcs) having either imidazole (ZnPc 1) or pyridiloxy (ZnPc 2) moieties as their macrocycle substituents are reported. Quaternization of the ZnPcs with methyl iodide afforded water soluble cationic phthalocyanines. The photophysical, photochemical properties and photodynamic therapy (PDT) activity of the ZnPcs were studied in solution. The fluorescence quantum yield and lifetime of ZnPc 1 were higher as compared to ZnPc 2. ZnPc 2 afforded higher triplet state (ΦT) and singlet oxygen quantum yields (ΦΔ) in comparison to ZnPc 1. The PDT activity of ZnPcs was investigated against human breast adenocarcinoma cells (MCF–7). The two compounds afforded a very minimal in vitro dark cytotoxicity with 85% viable cells at concentration ≤80 μM. On irradiation of the cells having the ZnPcs, ≥50% cell death was recorded for ZnPc 1 which was also evidenced by the cells photo–micrograph.
- Full Text:
- Date Issued: 2018
- Authors: Oluwole, David O , Sari, Fatma Aslihan , Prinsloo, Earl , Dube, Edith , Yuzer, Abdulcelil , Nyokong, Tebello , Ince, Mine
- Date: 2018
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/234507 , vital:50203 , xlink:href="https://doi.org/10.1016/j.saa.2018.05.090"
- Description: The syntheses of two zinc(II) phthalocyanines (ZnPcs) having either imidazole (ZnPc 1) or pyridiloxy (ZnPc 2) moieties as their macrocycle substituents are reported. Quaternization of the ZnPcs with methyl iodide afforded water soluble cationic phthalocyanines. The photophysical, photochemical properties and photodynamic therapy (PDT) activity of the ZnPcs were studied in solution. The fluorescence quantum yield and lifetime of ZnPc 1 were higher as compared to ZnPc 2. ZnPc 2 afforded higher triplet state (ΦT) and singlet oxygen quantum yields (ΦΔ) in comparison to ZnPc 1. The PDT activity of ZnPcs was investigated against human breast adenocarcinoma cells (MCF–7). The two compounds afforded a very minimal in vitro dark cytotoxicity with 85% viable cells at concentration ≤80 μM. On irradiation of the cells having the ZnPcs, ≥50% cell death was recorded for ZnPc 1 which was also evidenced by the cells photo–micrograph.
- Full Text:
- Date Issued: 2018