Determining the hydrological functioning of the palmiet wetlands in the Eastern and Western Cape South Africa
- Authors: Smith, Caitlin
- Date: 2019
- Subjects: Wetlands -- South Africa -- Eastern Cape , Wetland ecology -- South Africa -- Eastern Cape , Wetland management -- South Africa -- Eastern Cape , Prioniaceae -- South Africa -- Eastern Cape , Prionium serratum -- South Africa -- Eastern Cape
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/95956 , vital:31218
- Description: Wetlands provide a range of supporting, regulating and provisioning ecosystem services, including hydrological benefits such as flood attenuation and sustaining base flows. Despite their value, wetlands are one of the most vulnerable ecosystems in South Africa. Palmiet wetlands in the Eastern and Western Cape are particularly threatened. Palmiet (Prionium serratum) is a robust perennial plant that is endemic to wetlands and rivers located in the sandstones and quartzites of the Table Mountain Group (TMG), in the Eastern and Western Cape as well as the Natal Group sandstones in KwaZulu-Natal. Palmiet is described as an ecosystem engineer because of its ability to alter its environment and create large valley-bottom wetlands. The Krom River is an important water source for the city of Port Elizabeth and there has been a decline in palmiet wetlands along the Krom River as a result of alien vegetation invasion, agricultural activity, and gully erosion. Working for Water has been clearing alien vegetation and Working for Wetlands has been installing rehabilitation structures in the Krom River catchment for a number of years. There are, however, serious knowledge gaps in the understanding of palmiet wetland structure and function, particularly in respect of the hydrological functioning of these wetland systems. The aim of this study was to investigate the hydrology (surface and groundwater) behind these wetland systems. The investigation focussed on small-scale dynamics of the palmiet wetland system in order to increase general understanding of the surface water and groundwater processes of these wetland systems. Field work was concentrated on the Kompanjiesdrif and Krugersland palmiet wetlands in the upper K90A Krom River catchment. The investigation involved the installation of piezometers, water quality and stable isotope sampling and analysis, an Electrical Resistivity Tomography survey, and hydrological and mixing cell modelling. The results of the investigation indicate that the hydrological functioning of palmiet wetlands is closely linked with high sub-surface discharges typically associated with TMG aquifers. It is proposed that the palmiet wetlands are sustained by significant amounts of sub-surface water (both groundwater and interflow) moving through preferential flow paths in the alluvial fans and tributaries, which are in turn sustained by groundwater discharge from the surrounding sandstones and quartzites of the Nardouw Sub-group and Peninsula Formation. The palmiet wetlands clearly retain a significant amount of water, leading to the maintenance of prolonged flows, and a larger baseflow. However, it is hypothesised that the occurrence of palmiet as the dominant species in these wetlands is due to the sustained low flows related to catchment geology and high hydrological connectivity between the catchment and the wetland that is enabled by flow paths that allow the free flow of water from the catchment to the wetland. It is further proposed that palmiet is possibly more reliant on a consistent water supply for its existence and survival than it is on acidic nutrient-poor water and soils as stated by other authors.
- Full Text:
- Date Issued: 2019
- Authors: Smith, Caitlin
- Date: 2019
- Subjects: Wetlands -- South Africa -- Eastern Cape , Wetland ecology -- South Africa -- Eastern Cape , Wetland management -- South Africa -- Eastern Cape , Prioniaceae -- South Africa -- Eastern Cape , Prionium serratum -- South Africa -- Eastern Cape
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/95956 , vital:31218
- Description: Wetlands provide a range of supporting, regulating and provisioning ecosystem services, including hydrological benefits such as flood attenuation and sustaining base flows. Despite their value, wetlands are one of the most vulnerable ecosystems in South Africa. Palmiet wetlands in the Eastern and Western Cape are particularly threatened. Palmiet (Prionium serratum) is a robust perennial plant that is endemic to wetlands and rivers located in the sandstones and quartzites of the Table Mountain Group (TMG), in the Eastern and Western Cape as well as the Natal Group sandstones in KwaZulu-Natal. Palmiet is described as an ecosystem engineer because of its ability to alter its environment and create large valley-bottom wetlands. The Krom River is an important water source for the city of Port Elizabeth and there has been a decline in palmiet wetlands along the Krom River as a result of alien vegetation invasion, agricultural activity, and gully erosion. Working for Water has been clearing alien vegetation and Working for Wetlands has been installing rehabilitation structures in the Krom River catchment for a number of years. There are, however, serious knowledge gaps in the understanding of palmiet wetland structure and function, particularly in respect of the hydrological functioning of these wetland systems. The aim of this study was to investigate the hydrology (surface and groundwater) behind these wetland systems. The investigation focussed on small-scale dynamics of the palmiet wetland system in order to increase general understanding of the surface water and groundwater processes of these wetland systems. Field work was concentrated on the Kompanjiesdrif and Krugersland palmiet wetlands in the upper K90A Krom River catchment. The investigation involved the installation of piezometers, water quality and stable isotope sampling and analysis, an Electrical Resistivity Tomography survey, and hydrological and mixing cell modelling. The results of the investigation indicate that the hydrological functioning of palmiet wetlands is closely linked with high sub-surface discharges typically associated with TMG aquifers. It is proposed that the palmiet wetlands are sustained by significant amounts of sub-surface water (both groundwater and interflow) moving through preferential flow paths in the alluvial fans and tributaries, which are in turn sustained by groundwater discharge from the surrounding sandstones and quartzites of the Nardouw Sub-group and Peninsula Formation. The palmiet wetlands clearly retain a significant amount of water, leading to the maintenance of prolonged flows, and a larger baseflow. However, it is hypothesised that the occurrence of palmiet as the dominant species in these wetlands is due to the sustained low flows related to catchment geology and high hydrological connectivity between the catchment and the wetland that is enabled by flow paths that allow the free flow of water from the catchment to the wetland. It is further proposed that palmiet is possibly more reliant on a consistent water supply for its existence and survival than it is on acidic nutrient-poor water and soils as stated by other authors.
- Full Text:
- Date Issued: 2019
Developing Mother Tongues as Academic Languages in Primary Schools in Kenya: Exploring Extent and Indispensability
- Mose, Peter N, Kaschula, Russell H
- Authors: Mose, Peter N , Kaschula, Russell H
- Date: 2019
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/174793 , vital:42510 , https://doi.org/10.1080/15348458.2019.1645605
- Description: The language in education policy in Kenya recommends mother tongue education in primary school learning. The purpose of this study was to explore the development of mother tongues as academic languages at the lower primary section in which the languages are supposed to be used. The exploration was on the functions they play in classroom instruction and if they are dispensable or otherwise. Ekegusii was used as a case study. Data were obtained through classroom observations and administration of semi-structured interviews with lower primary teachers. The findings indicate that mother tongues play important pedagogical functions in grades 1 up to 3, but not exactly as contemplated in the language policy. Secondly, mother tongues are indispensable in classroom teaching in spite of negative attitude towards their use.
- Full Text:
- Date Issued: 2019
- Authors: Mose, Peter N , Kaschula, Russell H
- Date: 2019
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/174793 , vital:42510 , https://doi.org/10.1080/15348458.2019.1645605
- Description: The language in education policy in Kenya recommends mother tongue education in primary school learning. The purpose of this study was to explore the development of mother tongues as academic languages at the lower primary section in which the languages are supposed to be used. The exploration was on the functions they play in classroom instruction and if they are dispensable or otherwise. Ekegusii was used as a case study. Data were obtained through classroom observations and administration of semi-structured interviews with lower primary teachers. The findings indicate that mother tongues play important pedagogical functions in grades 1 up to 3, but not exactly as contemplated in the language policy. Secondly, mother tongues are indispensable in classroom teaching in spite of negative attitude towards their use.
- Full Text:
- Date Issued: 2019
Developing ocean particle tracking tools for cross-disciplinary oceanic research with applications in the Agulhas current region
- Hart-Davis, Michael Geofrey, Backeberg, Björn C
- Authors: Hart-Davis, Michael Geofrey , Backeberg, Björn C
- Date: 2019
- Subjects: Ocean currents , Ocean currents -- Measurement Oceanography Oceanography -- Research -- South Atlantic Ocean
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/42308 , vital:36644
- Description: Lagrangian ocean analysis is a powerful way to study ocean processes from in-situ observations and numerical model simulations. As numerical modelling capabilities develop and physical mechanisms of the ocean are better understood, the importance of particle trajectory modelling continues to increase. Therefore, developing cross-disciplinary particle trajectory model applications for the Greater Agulhas System is highly relevant due to its potential contribution to scientific studies and operational applications. This thesis presents the results of developing particle trajectory model applications in the Greater Agulhas System towards better understanding the physical mechanisms that drive ocean processes in the region. The model is used in three applications that demonstrate their cross-disciplinary potential. These applications include a search and rescue scenario, the study of ocean dynamics and the study of the fate of juvenile turtles. Introducing spatially and temporally varying stochastic motion to account for the processes not resolved in the ocean surface current products, as well as including more appropriate boundary conditions, were shown to improve the accuracy of virtual drifters in representing the trajectory of a real surface drifter. Next, implementing the spatially and temporally varying stochastic motion in the particle trajectory model and applying it to a search and rescue scenario of a capsized catamaran revealed that including both winds and surface ocean currents in the particle trajectory model allowed for an improved prediction of the capsized vessel’s trajectory. By comparing a pair of real surface drifters with the particle trajectory model and analysing high resolution sea surface temperature (SST) fields it was shown that the formation of an eddy on the Agulhas Plateau combined with the weakening of the core current velocity resulted in enhanced eddycurrent interactions facilitating the separation of the real surface drifter-pair as they passed through this region. Lastly, the particle trajectory model was used to study the importance of including active swimming characteristic when studying the fate of juvenile turtles. It was found that including active swimming resulted in a change in the distribution of juvenile turtles and, therefore, needs to be included to provide a proper understanding of the fate of juvenile turtles in the ocean. With further development and refinement of the particle trajectory model, Lagrangian ocean analysis has the potential to provide valuable information towards improving our understanding of physical and biological ocean processes at a range of spatial and temporal scales with potential operational oceanography applications.
- Full Text:
- Date Issued: 2019
- Authors: Hart-Davis, Michael Geofrey , Backeberg, Björn C
- Date: 2019
- Subjects: Ocean currents , Ocean currents -- Measurement Oceanography Oceanography -- Research -- South Atlantic Ocean
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/42308 , vital:36644
- Description: Lagrangian ocean analysis is a powerful way to study ocean processes from in-situ observations and numerical model simulations. As numerical modelling capabilities develop and physical mechanisms of the ocean are better understood, the importance of particle trajectory modelling continues to increase. Therefore, developing cross-disciplinary particle trajectory model applications for the Greater Agulhas System is highly relevant due to its potential contribution to scientific studies and operational applications. This thesis presents the results of developing particle trajectory model applications in the Greater Agulhas System towards better understanding the physical mechanisms that drive ocean processes in the region. The model is used in three applications that demonstrate their cross-disciplinary potential. These applications include a search and rescue scenario, the study of ocean dynamics and the study of the fate of juvenile turtles. Introducing spatially and temporally varying stochastic motion to account for the processes not resolved in the ocean surface current products, as well as including more appropriate boundary conditions, were shown to improve the accuracy of virtual drifters in representing the trajectory of a real surface drifter. Next, implementing the spatially and temporally varying stochastic motion in the particle trajectory model and applying it to a search and rescue scenario of a capsized catamaran revealed that including both winds and surface ocean currents in the particle trajectory model allowed for an improved prediction of the capsized vessel’s trajectory. By comparing a pair of real surface drifters with the particle trajectory model and analysing high resolution sea surface temperature (SST) fields it was shown that the formation of an eddy on the Agulhas Plateau combined with the weakening of the core current velocity resulted in enhanced eddycurrent interactions facilitating the separation of the real surface drifter-pair as they passed through this region. Lastly, the particle trajectory model was used to study the importance of including active swimming characteristic when studying the fate of juvenile turtles. It was found that including active swimming resulted in a change in the distribution of juvenile turtles and, therefore, needs to be included to provide a proper understanding of the fate of juvenile turtles in the ocean. With further development and refinement of the particle trajectory model, Lagrangian ocean analysis has the potential to provide valuable information towards improving our understanding of physical and biological ocean processes at a range of spatial and temporal scales with potential operational oceanography applications.
- Full Text:
- Date Issued: 2019
Development and characterisation of miconazole nitrate loaded solid lipid nanoparticles for incorporation into a vaginal mucoadhesive system
- Authors: Gwimo, Wimana Alexis
- Date: 2019
- Subjects: Vaginitis , Vagina -- Diseases Sexually transmitted diseases -- Diagnosis Sexually transmitted diseases -- Treatment
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/39632 , vital:35335
- Description: Vulvovaginal candidiasis (VVC) is the second most common cause of vaginitis, affecting 75% of women of sexual maturity. The prescribed first line treatment involves the use of locally-acting imidazole creams. These conventional dosage forms possess limitations, such as leakage, messiness and low residence time at the site of application; all which promote poor patient adherence to pharmacotherapy. Poor adherence is then attributed to increased incidence of VVC reoccurrence and the emergence of Candida strains. It was, therefore, speculated that through the use of novel drug delivery systems (NDDS), the pharmacokinetic and antimicrobial characteristics of a model antifungal drug (miconazole nitrate [MNZ]) could be improved. Primary aim: To develop, optimise and characterise a mucoadhesive hydrogel incorporated with MNZ loaded solid lipid nanoparticles (MNZ-SLNs) for the intended treatment of VVC. This study was conducted in three phases, viz. pre-formulation studies, development, optimisation and characterisation of MNZ-SLNs, and the development and characterisation of MNZ-SLN-loaded thermoresponsive hydrogel. An alternative method for the quantification of MNZ was developed through the use of an octyl stationary phase. The method was deemed suitable for its intended use with a linear equation of y = 811214x + 67958 and a respective limit of quantitation (LoQ) and detection of 0.015 mg/ml and 0.052 mg/ml. Differential scanning calorimetry (DSC) studies suggested that cholesterol showed great promise of facilitating high drug entrapment efficiency (EE). MNZ-SLNs were prepared by means of a novel melt- emulsification sonication and low temperature solidification method and optimised statistically by a 13-run-two-factor central composite rotatable design (CCRD). The predicted optimisation parameters were 4% m/v lipid concentration and 260.94 sonication time. Optimal MNZ-SLN formulations were prepared and characterised by means of photon correlation spectroscopy (PCS), transmission electron microscopy (TEM) and centrifugation. PCS revealed uniform particles with a narrow polydispersity index (PDI) and a mean hydrodynamic diameter (z-avg.) of 73.03 nm and zeta potential (ZP) of 38.43 mV. Percent EE was calculated via an indirect method as 75.24%. Furthermore, the MNZ -SLNs were incorporated into a mucoadhesive thermo-responsive hydrogel with a sol-gel transition temperature of 33.33 ± 2.82 °C. In vitro drug release testing (IVDRT) was undertaken with the aid of a Franz diffusion vertical cell (FDVC) apparatus. A % cumulative drug release of 27.94% and 15.87% was obtained for MNZ- SLNs and MNZ-SLN hydrogels, respectively, after eight hours. The resultant data was fitted into various kinetic models with the aid of DDSolverTM (Microsoft Excel® add-ins, 2016) to evaluate which model attained the highest correlation co-efficient (r2). Both formulations attained high r2 of 0.9941 and 0.9945, respectively, with the Korsmeyer- Peppas mathematical model. A high diffusional exponent (n) of >1 was observed, suggesting a super case II drug release mechanism. Finally, a modified Kirby-Bauer disc diffusion assay was used for ascertaining Candida albicans susceptibility to the developed formulations. Controls in the form of unloaded preparations and a commercially available cream were used. MNZ-SLNs and MNZ-hydrogel demonstrated superior antifungal activity to the commercially available cream. These results indicate that the developed MNZ-SLNloaded hydrogel formulation with localised thermo-responsive effect may be a promising carrier for intravaginal delivery of MNZ in the treatment of VVC.
- Full Text:
- Date Issued: 2019
- Authors: Gwimo, Wimana Alexis
- Date: 2019
- Subjects: Vaginitis , Vagina -- Diseases Sexually transmitted diseases -- Diagnosis Sexually transmitted diseases -- Treatment
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/39632 , vital:35335
- Description: Vulvovaginal candidiasis (VVC) is the second most common cause of vaginitis, affecting 75% of women of sexual maturity. The prescribed first line treatment involves the use of locally-acting imidazole creams. These conventional dosage forms possess limitations, such as leakage, messiness and low residence time at the site of application; all which promote poor patient adherence to pharmacotherapy. Poor adherence is then attributed to increased incidence of VVC reoccurrence and the emergence of Candida strains. It was, therefore, speculated that through the use of novel drug delivery systems (NDDS), the pharmacokinetic and antimicrobial characteristics of a model antifungal drug (miconazole nitrate [MNZ]) could be improved. Primary aim: To develop, optimise and characterise a mucoadhesive hydrogel incorporated with MNZ loaded solid lipid nanoparticles (MNZ-SLNs) for the intended treatment of VVC. This study was conducted in three phases, viz. pre-formulation studies, development, optimisation and characterisation of MNZ-SLNs, and the development and characterisation of MNZ-SLN-loaded thermoresponsive hydrogel. An alternative method for the quantification of MNZ was developed through the use of an octyl stationary phase. The method was deemed suitable for its intended use with a linear equation of y = 811214x + 67958 and a respective limit of quantitation (LoQ) and detection of 0.015 mg/ml and 0.052 mg/ml. Differential scanning calorimetry (DSC) studies suggested that cholesterol showed great promise of facilitating high drug entrapment efficiency (EE). MNZ-SLNs were prepared by means of a novel melt- emulsification sonication and low temperature solidification method and optimised statistically by a 13-run-two-factor central composite rotatable design (CCRD). The predicted optimisation parameters were 4% m/v lipid concentration and 260.94 sonication time. Optimal MNZ-SLN formulations were prepared and characterised by means of photon correlation spectroscopy (PCS), transmission electron microscopy (TEM) and centrifugation. PCS revealed uniform particles with a narrow polydispersity index (PDI) and a mean hydrodynamic diameter (z-avg.) of 73.03 nm and zeta potential (ZP) of 38.43 mV. Percent EE was calculated via an indirect method as 75.24%. Furthermore, the MNZ -SLNs were incorporated into a mucoadhesive thermo-responsive hydrogel with a sol-gel transition temperature of 33.33 ± 2.82 °C. In vitro drug release testing (IVDRT) was undertaken with the aid of a Franz diffusion vertical cell (FDVC) apparatus. A % cumulative drug release of 27.94% and 15.87% was obtained for MNZ- SLNs and MNZ-SLN hydrogels, respectively, after eight hours. The resultant data was fitted into various kinetic models with the aid of DDSolverTM (Microsoft Excel® add-ins, 2016) to evaluate which model attained the highest correlation co-efficient (r2). Both formulations attained high r2 of 0.9941 and 0.9945, respectively, with the Korsmeyer- Peppas mathematical model. A high diffusional exponent (n) of >1 was observed, suggesting a super case II drug release mechanism. Finally, a modified Kirby-Bauer disc diffusion assay was used for ascertaining Candida albicans susceptibility to the developed formulations. Controls in the form of unloaded preparations and a commercially available cream were used. MNZ-SLNs and MNZ-hydrogel demonstrated superior antifungal activity to the commercially available cream. These results indicate that the developed MNZ-SLNloaded hydrogel formulation with localised thermo-responsive effect may be a promising carrier for intravaginal delivery of MNZ in the treatment of VVC.
- Full Text:
- Date Issued: 2019
Development and Validation of a Stability-indicating RP-HPLC Method Using Quality by Design for Estimating Captopril
- Veerubhotla, Krishna, Walker, Roderick B
- Authors: Veerubhotla, Krishna , Walker, Roderick B
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/183525 , vital:44003 , xlink:href="10.4172/pharmaceutical-sciences.1000478"
- Description: The applicability of a quality by design framework for the development of a sensitive, simple and selective, stability-indicating reversed-phase high-performance liquid chromatography analytical method for the analysis of captopril was investigated. Design of experiments using a central composite design approach was used for method development. Twenty experimental runs were performed with acetonitrile content ranging between 28 and 36 % v/v, pH from 2.8 to 3.6 and temperature between 22° and 32°. The experimental data obtained was used to derive a quadratic model for the retention time of captopril. The optimized method produced sharp peaks with good resolution (>2) for captopril and the internal standard with retention times of 3.1 and 6.2 min, respectively. The experimental data revealed that acetonitrile content in the mobile phase and pH are significant factors that affect the retention time and resolution of captopril. Normal probability plots revealed that the residual and predicted data fall approximately on a straight line, indicating that the experimental error for these studies was evenly distributed suggesting that the model could be used to navigate the design space. This approach is useful to expedite method development and optimization activities in analytical laboratories.
- Full Text:
- Date Issued: 2019
- Authors: Veerubhotla, Krishna , Walker, Roderick B
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/183525 , vital:44003 , xlink:href="10.4172/pharmaceutical-sciences.1000478"
- Description: The applicability of a quality by design framework for the development of a sensitive, simple and selective, stability-indicating reversed-phase high-performance liquid chromatography analytical method for the analysis of captopril was investigated. Design of experiments using a central composite design approach was used for method development. Twenty experimental runs were performed with acetonitrile content ranging between 28 and 36 % v/v, pH from 2.8 to 3.6 and temperature between 22° and 32°. The experimental data obtained was used to derive a quadratic model for the retention time of captopril. The optimized method produced sharp peaks with good resolution (>2) for captopril and the internal standard with retention times of 3.1 and 6.2 min, respectively. The experimental data revealed that acetonitrile content in the mobile phase and pH are significant factors that affect the retention time and resolution of captopril. Normal probability plots revealed that the residual and predicted data fall approximately on a straight line, indicating that the experimental error for these studies was evenly distributed suggesting that the model could be used to navigate the design space. This approach is useful to expedite method development and optimization activities in analytical laboratories.
- Full Text:
- Date Issued: 2019
Development of a framework for a proposed antimicrobial usage reporting tool for public sector hospitals
- Authors: Ramjan, Yumna
- Date: 2019
- Subjects: Anti-infective agents
- Language: English
- Type: Thesis , Masters , MPharm
- Identifier: http://hdl.handle.net/10948/43030 , vital:36727
- Description: Background: The inappropriate and unnecessary use of antimicrobials has increased the need to monitor antimicrobial usage so as to identify inappropriate use. In order to support the antimicrobial stewardship (AMS) programme, it is important to quantify the usage of antimicrobials and this can be achieved by promoting the use of AMS utilisation metrics. They are used to measure the progress and efficacy of an AMS programme (Brotherton, 2018).Primary Aim of Research: The primary aim of the research was to develop a framework for a proposed antimicrobial usage reporting tool, which would integrate with various data sources in order to be used by AMS practitioners to optimise antimicrobial usage in the South African public sector hospital setting.Methodology: The study was divided into three phases: a preliminary phase, a developmental phase and a post-developmental phase. The preliminary phase focused on obtaining a comprehensive understanding of the type and nature of the AMS utilisation metrics and subsequently identifying the views on the usage, usefulness and clinical relevance of those AMS utilisation metrics using a quantitative questionnaire, which was conducted among infectious disease specialists, pharmacists, medical prescribers, i.e. prescribers who were not specialists and clinical pathologists employed at tertiary level, public sector hospitals in the Eastern Cape province of South Africa. Consequently, a qualitative semi-structured interview was conducted among healthcare professionals who were involved in the daily implementation of AMS in the workplace. Results obtained from the quantitative component and qualitative component were integrated in order to develop a framework for a proposed antimicrobial usage reporting tool. Results: The Defined Daily Dose (DDD), Prescribed Daily Dose (PDD) and Days of Therapy (DOT) were identified as the most common AMS metrics (Grau et al., 2013). However, the DDD was the only AMS metric currently recommended by the South African National Department of Health (South African National Department of Health, 2017a)and it was the only AMS metric currently being utilised at two of the five research sites in the Eastern Cape province of South Africa. It was identified that data pertaining to antimicrobial usage was available and was being extracted from Rx Solution®. However, the programme did not have the ability of automatically producing the reports, hence, emphasising on the need for an antimicrobial usage reporting tool for South African public sector hospitals. Therefore, the framework for the proposed antimicrobial usage reporting tool would integrate antimicrobial stock management data with the following AMS utilisation metrics: DDD, DOT and PDD, were considered for inclusion in the proposed antimicrobial usage reporting tool. Conclusion: The qualitative findings obtained during the post-developmental phase, therefore, established that although an electronic platform for the purpose of monitoring antimicrobial usage for the South African public sector hospitals was required, there would be many challenges obstructing the implementation of the proposed antimicrobial usage reporting tool.
- Full Text:
- Date Issued: 2019
- Authors: Ramjan, Yumna
- Date: 2019
- Subjects: Anti-infective agents
- Language: English
- Type: Thesis , Masters , MPharm
- Identifier: http://hdl.handle.net/10948/43030 , vital:36727
- Description: Background: The inappropriate and unnecessary use of antimicrobials has increased the need to monitor antimicrobial usage so as to identify inappropriate use. In order to support the antimicrobial stewardship (AMS) programme, it is important to quantify the usage of antimicrobials and this can be achieved by promoting the use of AMS utilisation metrics. They are used to measure the progress and efficacy of an AMS programme (Brotherton, 2018).Primary Aim of Research: The primary aim of the research was to develop a framework for a proposed antimicrobial usage reporting tool, which would integrate with various data sources in order to be used by AMS practitioners to optimise antimicrobial usage in the South African public sector hospital setting.Methodology: The study was divided into three phases: a preliminary phase, a developmental phase and a post-developmental phase. The preliminary phase focused on obtaining a comprehensive understanding of the type and nature of the AMS utilisation metrics and subsequently identifying the views on the usage, usefulness and clinical relevance of those AMS utilisation metrics using a quantitative questionnaire, which was conducted among infectious disease specialists, pharmacists, medical prescribers, i.e. prescribers who were not specialists and clinical pathologists employed at tertiary level, public sector hospitals in the Eastern Cape province of South Africa. Consequently, a qualitative semi-structured interview was conducted among healthcare professionals who were involved in the daily implementation of AMS in the workplace. Results obtained from the quantitative component and qualitative component were integrated in order to develop a framework for a proposed antimicrobial usage reporting tool. Results: The Defined Daily Dose (DDD), Prescribed Daily Dose (PDD) and Days of Therapy (DOT) were identified as the most common AMS metrics (Grau et al., 2013). However, the DDD was the only AMS metric currently recommended by the South African National Department of Health (South African National Department of Health, 2017a)and it was the only AMS metric currently being utilised at two of the five research sites in the Eastern Cape province of South Africa. It was identified that data pertaining to antimicrobial usage was available and was being extracted from Rx Solution®. However, the programme did not have the ability of automatically producing the reports, hence, emphasising on the need for an antimicrobial usage reporting tool for South African public sector hospitals. Therefore, the framework for the proposed antimicrobial usage reporting tool would integrate antimicrobial stock management data with the following AMS utilisation metrics: DDD, DOT and PDD, were considered for inclusion in the proposed antimicrobial usage reporting tool. Conclusion: The qualitative findings obtained during the post-developmental phase, therefore, established that although an electronic platform for the purpose of monitoring antimicrobial usage for the South African public sector hospitals was required, there would be many challenges obstructing the implementation of the proposed antimicrobial usage reporting tool.
- Full Text:
- Date Issued: 2019
Development of a manual to train food handlers of the national school nutrition programme
- Authors: Barkhuizen, Kirsten Lyn
- Date: 2019
- Subjects: Food -- Safety measures
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/36559 , vital:33974
- Description: The study was conducted in order to develop a hygiene and food safety manual that can be used to train the food handlers of the National School Nutrition Programme. The co-operation of the Institute for International Medicine, Partnerships with Children, as part of the Health in Action Programme in this study, is appreciated. Food handlers of the National School Nutrition Programme in low socio-economic schools, in the Nelson Mandela Bay, in the Eastern Cape, were the population of the study. With many South Africans experiencing poverty and food insecurity, the National School Nutrition Programme aims to provide a social safety net and address short term hunger in children. However, challenges are faced regarding the implementation thereof, such as a lack of training of food handlers. This results in poor hygiene and food safety knowledge and behaviour. Subsequently, the risk of transmission of foodborne pathogens and the contamination of food rises. Foodborne illnesses are a major cause of morbidity and mortality, specifically in children, due to weak immune systems. Therefore, the study was conducted in order to develop and test a hygiene and food safety manual so that it can be made available to the South African Department of Education to be used by teachers in order to train the food handlers of the National School Nutrition Programme. The manual can then be used to train all newly recruited food handlers, and therefore ensure that school meals are safe to consume by learners.
- Full Text:
- Date Issued: 2019
- Authors: Barkhuizen, Kirsten Lyn
- Date: 2019
- Subjects: Food -- Safety measures
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/36559 , vital:33974
- Description: The study was conducted in order to develop a hygiene and food safety manual that can be used to train the food handlers of the National School Nutrition Programme. The co-operation of the Institute for International Medicine, Partnerships with Children, as part of the Health in Action Programme in this study, is appreciated. Food handlers of the National School Nutrition Programme in low socio-economic schools, in the Nelson Mandela Bay, in the Eastern Cape, were the population of the study. With many South Africans experiencing poverty and food insecurity, the National School Nutrition Programme aims to provide a social safety net and address short term hunger in children. However, challenges are faced regarding the implementation thereof, such as a lack of training of food handlers. This results in poor hygiene and food safety knowledge and behaviour. Subsequently, the risk of transmission of foodborne pathogens and the contamination of food rises. Foodborne illnesses are a major cause of morbidity and mortality, specifically in children, due to weak immune systems. Therefore, the study was conducted in order to develop and test a hygiene and food safety manual so that it can be made available to the South African Department of Education to be used by teachers in order to train the food handlers of the National School Nutrition Programme. The manual can then be used to train all newly recruited food handlers, and therefore ensure that school meals are safe to consume by learners.
- Full Text:
- Date Issued: 2019
Development of a nystatin-loaded micellar system for oral mucoadhesion
- Authors: Sarpong, Nancy Owusu Akyere
- Date: 2019
- Subjects: Medical microbiology , HIV infections -- Treatment Clinical pharmacology
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/43556 , vital:36918
- Description: Oropharyngeal Candidiasis (OPC) is an opportunistic fungal infection that affects mostly infants and immunocompromised patients. In recent years, the disease has been on the rise due to an increased life span, the HIV pandemic and the increased use of broad spectrum antibiotics. OPC may be treated using a nystatin suspension, which is not as effective as it could be due to the mechanism by which the suspension is applied to the affected tissue. This research aims to improve the effectiveness of nystatin, for the treatment of OPC, by proposing a nystatin loaded micellar system incorporated into a mucoadhesive system for drug delivery. This will ensure that nystatin is gradually released from the film, thus increasing retention time of nystatin at the affected area. In this study, a mixture design was developed, which was used to determine the most appropriate solvent system for nystatin solubilization. Optimisation of the micelle formulation was achieved by using the central composite rational design (CCRD). The two factors that were taken into consideration were the temperature of the hydration medium (water) and the length of time the micellar solution was exposed to the temperature environment of the rotary evaporator. The responses that were investigated were the mean particle size, mean polydispersity index (PDI), mean zeta potential, change in mean particle size and change in mean PDI. The optimal micelle formulation was characterised for size, stability, morphology and drug encapsulation efficiency. The micelles were found to be spherical and stable with an acceptable size range. However, their drug encapsulation efficiency was low. The mucoadhesive film was formulated and characterised for physical characteristics, pliability, percentage swelling index and drug release profile. The film was found to be highly pliable and evenly distributed with a smooth surface; no bumps or bubbles were visible. The film was able to swell to up to 550 %. In vitro studies showed that nystatin was gradually released from the film.
- Full Text:
- Date Issued: 2019
- Authors: Sarpong, Nancy Owusu Akyere
- Date: 2019
- Subjects: Medical microbiology , HIV infections -- Treatment Clinical pharmacology
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/43556 , vital:36918
- Description: Oropharyngeal Candidiasis (OPC) is an opportunistic fungal infection that affects mostly infants and immunocompromised patients. In recent years, the disease has been on the rise due to an increased life span, the HIV pandemic and the increased use of broad spectrum antibiotics. OPC may be treated using a nystatin suspension, which is not as effective as it could be due to the mechanism by which the suspension is applied to the affected tissue. This research aims to improve the effectiveness of nystatin, for the treatment of OPC, by proposing a nystatin loaded micellar system incorporated into a mucoadhesive system for drug delivery. This will ensure that nystatin is gradually released from the film, thus increasing retention time of nystatin at the affected area. In this study, a mixture design was developed, which was used to determine the most appropriate solvent system for nystatin solubilization. Optimisation of the micelle formulation was achieved by using the central composite rational design (CCRD). The two factors that were taken into consideration were the temperature of the hydration medium (water) and the length of time the micellar solution was exposed to the temperature environment of the rotary evaporator. The responses that were investigated were the mean particle size, mean polydispersity index (PDI), mean zeta potential, change in mean particle size and change in mean PDI. The optimal micelle formulation was characterised for size, stability, morphology and drug encapsulation efficiency. The micelles were found to be spherical and stable with an acceptable size range. However, their drug encapsulation efficiency was low. The mucoadhesive film was formulated and characterised for physical characteristics, pliability, percentage swelling index and drug release profile. The film was found to be highly pliable and evenly distributed with a smooth surface; no bumps or bubbles were visible. The film was able to swell to up to 550 %. In vitro studies showed that nystatin was gradually released from the film.
- Full Text:
- Date Issued: 2019
Development of an Extensible Framework for Easy Implementation of Image Processing Applications on Android Operating System
- Authors: Gunu, Bulelani
- Date: 2019
- Subjects: Operating systems (Computers)
- Language: English
- Type: Thesis , Masters , MSc (Computer Science )
- Identifier: http://hdl.handle.net/10353/17201 , vital:40865
- Description: Image processing is a field that has been in existence for many years and it continues to grow with many other research areas adopting its use. One such research area is the area of mobile devices. Mobile devices have been equipped with image processing software and hardware so as to apply image processing features. While there are many applications of image processing and new applications have been developed, there are still many functionalities that these image processing software perform the same. The development of these software from scratch requires a lot of effort and can be time consuming. This becomes even worse for mobile device application developers, specifically Android developers, who have no knowledge of implementing image processing functionalities. This project offers a software framework which allows Android application developers to focus on their unique requirements while incorporating image processing features into their applications. The framework provides the common image processing functionalities and Android developers do not need to know the internal working of the framework in order to use it. This helps reduce application development time and effort. The framework also offers an extensibility feature which takes into consideration the future growth. This means that third party developers can keep the framework up to date with the technological advancements. The presented framework is shown to be requiring less technical expertise. Also, the way in which the system is design makes it easy to understand. This design can be adopted for other related projects that require extensible frameworks for the Android operating system.
- Full Text:
- Date Issued: 2019
- Authors: Gunu, Bulelani
- Date: 2019
- Subjects: Operating systems (Computers)
- Language: English
- Type: Thesis , Masters , MSc (Computer Science )
- Identifier: http://hdl.handle.net/10353/17201 , vital:40865
- Description: Image processing is a field that has been in existence for many years and it continues to grow with many other research areas adopting its use. One such research area is the area of mobile devices. Mobile devices have been equipped with image processing software and hardware so as to apply image processing features. While there are many applications of image processing and new applications have been developed, there are still many functionalities that these image processing software perform the same. The development of these software from scratch requires a lot of effort and can be time consuming. This becomes even worse for mobile device application developers, specifically Android developers, who have no knowledge of implementing image processing functionalities. This project offers a software framework which allows Android application developers to focus on their unique requirements while incorporating image processing features into their applications. The framework provides the common image processing functionalities and Android developers do not need to know the internal working of the framework in order to use it. This helps reduce application development time and effort. The framework also offers an extensibility feature which takes into consideration the future growth. This means that third party developers can keep the framework up to date with the technological advancements. The presented framework is shown to be requiring less technical expertise. Also, the way in which the system is design makes it easy to understand. This design can be adopted for other related projects that require extensible frameworks for the Android operating system.
- Full Text:
- Date Issued: 2019
Development of high yielding strain of Pleurotus tuber-regium fructification, nutritional and phylogenetic studies
- Bamigboye, Comfort O, Oloke, Julius K, Dames, Joanna F
- Authors: Bamigboye, Comfort O , Oloke, Julius K , Dames, Joanna F
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/448595 , vital:74745 , https://doi.org/10.1007/s13197-019-03786-7
- Description: Mushrooms are nutritionally rich, healthy and medicinal. Pleurotus tuber-regium (Fr.) is one of the nutritious medicinal mushroom found in the tropics and subtropics, but with history of slow growth and low sclerotia yield. In this study, mutants were created by mycelia exposure to ultraviolet irradiation (at a wavelength of 254 nm and a distance of 45 cm), for 3 h and sub-cultured at 30 min interval. The DNA from the wild and mutant strains were extracted, PCR amplified and sequenced. A phylogenetic tree was constructed to show the degree of similarity and differences between the wild and the mutant strains. Fructification studies were conducted on Rhodes grass straw and sawdust to determine the viability of the mutant strains and any nutritional improvement. The wild strain of P. tuber-regium and mutant produced at 30 min (Pt30) cultivated on sawdust and Rhodes straw, yielded sclerotia with biological efficiency of 8.8 and 47.6% respectively. Proximate analysis of the sclerotium showed that the mutant, Pt30, had improved nutritional compositions compared to the wild strain with a total non-structural carbohydrate concentration of 2.41 g as against 0.93 g. Conclusively in this study, better strains of P. tuber-regium were produced with faster growth rate, higher mycelia ramification rate on lignocellulosic substrate and a higher sclerotia yield than the wild P. tuber-regium. It was also established that mutagenesis is capable of improving P. tuber-regium for a successful commercial venture in sclerotia production.
- Full Text:
- Date Issued: 2019
- Authors: Bamigboye, Comfort O , Oloke, Julius K , Dames, Joanna F
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/448595 , vital:74745 , https://doi.org/10.1007/s13197-019-03786-7
- Description: Mushrooms are nutritionally rich, healthy and medicinal. Pleurotus tuber-regium (Fr.) is one of the nutritious medicinal mushroom found in the tropics and subtropics, but with history of slow growth and low sclerotia yield. In this study, mutants were created by mycelia exposure to ultraviolet irradiation (at a wavelength of 254 nm and a distance of 45 cm), for 3 h and sub-cultured at 30 min interval. The DNA from the wild and mutant strains were extracted, PCR amplified and sequenced. A phylogenetic tree was constructed to show the degree of similarity and differences between the wild and the mutant strains. Fructification studies were conducted on Rhodes grass straw and sawdust to determine the viability of the mutant strains and any nutritional improvement. The wild strain of P. tuber-regium and mutant produced at 30 min (Pt30) cultivated on sawdust and Rhodes straw, yielded sclerotia with biological efficiency of 8.8 and 47.6% respectively. Proximate analysis of the sclerotium showed that the mutant, Pt30, had improved nutritional compositions compared to the wild strain with a total non-structural carbohydrate concentration of 2.41 g as against 0.93 g. Conclusively in this study, better strains of P. tuber-regium were produced with faster growth rate, higher mycelia ramification rate on lignocellulosic substrate and a higher sclerotia yield than the wild P. tuber-regium. It was also established that mutagenesis is capable of improving P. tuber-regium for a successful commercial venture in sclerotia production.
- Full Text:
- Date Issued: 2019
Development of polypropylene – waste tyre crumbs based tpe's with the aid of vistamaxxtm as a compatibiliser
- Authors: Masele, Siyamtanda
- Date: 2019
- Subjects: Polymers , Polymerization Crumb rubber Rubber
- Language: English
- Type: Thesis , Masters , MTech
- Identifier: http://hdl.handle.net/10948/42589 , vital:36670
- Description: Polypropylene (PP) is a semi crystalline thermoplastic polymer and one of the most commonly used polyolefins. It is well known for its poor impact resistance; hence, for industries such as the automotive and packaging, reinforced PP is widely used. In general plastic waste disposal is a global crisis raising environmental and human health concerns, with PP being the highest consumed polymer globally; hence a push in the reuse and recycling of PP. Recycled polypropylene has limited uses for industrial applications due to its highly reduced properties owing to the recycling process which inhabits cutting of chains lengths, broadened molecular weight distributions and compromised crystallinity. Several studies have investigated the use of reinforcing fillers and modifiers in order to improve properties of PP. Inorganic materials and minerals such as CaCO3, Mica, Talc and glass fibre are used as fillers to improve mechanical properties (tensile and hardness), but still lacks in improving the impact resistance. Thermoplastic elastomers (TPE) are typically used where elastomer and thermoplastics fail as individual components. This is because they have the benefit of thermoplastic properties at hypo ambient condition and elastomer properties such as good impact and elongation at sub-zero conditions. The study took a route of using PP and waste tyre crumb rubber (CR) material to prepare potentially low-cost waste based TPE’s, which would then inherit both properties of PP and the rubber component. VistamaxxTM 6202 (EPR), a commercial name for ethylene-propylene monomer (EPR), was used as a compatibiliser to improve interaction between PP and CR and to contribute towards the overall improvement of various properties such as mechanical properties. VistamaxxTM has a low glass transition temperature (Tg, = -30 ºC), which is important for low temperature applications such as cold storage; it also has a very high elongation and as a result contributed significantly to the overall properties when used in TPE blends. The study highlighted differences between two TPE compounding formulation pathways; namely master-batch (MB) and design of experiments (DoE). The MB formulations were blends that were prepared by a conventional way of compounding; where a pre-mixed CR/EPR blend, in the ratio of 80(CR):20(EPR), was used to form a master-batch. Results showed that there are some similarities between TPEs prepared in different ways, which suggests that the ultimate properties such as thermal stability are in fact more PP matrix based. Thermal analyses results revealed that when high amount of CR was added to the TPE blends, there was a substantial amount of residue mainly due to inherent carbon black. The degree of crystallinity of the blends decreased with increased amounts of CR irrespective of whether it was the MB or DoE blends. The MB TPE blends demonstrated that hardness is not linked to the amount of the MB nor the crystallinity of blends. Meanwhile, tensile elongation and tensile stress were affected by crystallinity. On the other hand, the impact strength findings showed that the amount of MB in TPE blends reached a threshold at 30%. The DoE based TPE blends demonstrated that the optimum mechanical properties are observed when components of the blends are incorporated individually during compounding. This was observed for impact strength, tensile stress as well as elongation at break. The results showed that the incorporation of EPR should be at least 20% for good impact and elongation properties; however, for tensile and hardness, the PP matrix must be high. The study also showed that, for better mechanical properties it was more suitable to use the blends formulated with DoE, because the master-batch approach limited the improving of the mechanical properties by an addition of up to 30% of both the CR and EPR. The storage modulus as well as the tan delta for both MB and DoE decreased when the elastomeric phases were added on both methods, whereas tan delta Tg values decreased as more of the elastomeric phase was added. Evidence from morphology studies showed that the majority of TPE blends suffer from inadequate distribution and adhesion between PP and elastomer; resulting in poor mechanical properties. Furthermore, a threshold of matrix invasion is observed from 30% and above of CR in the blend, where lack of in capsulated lamps of CR were observed hindering the stress induced crystallization and relaxation of the PP phase. The latter was observed irrespective of the type of blend, which strongly suggests and highlights the limits of blending PP with elastomers. Study demonstrated the ability of VistamaxxTM to be utilized as a binding material for PP and CR and displaying the challenges that might arise when used as a master-batch with crumb rubber.
- Full Text:
- Date Issued: 2019
- Authors: Masele, Siyamtanda
- Date: 2019
- Subjects: Polymers , Polymerization Crumb rubber Rubber
- Language: English
- Type: Thesis , Masters , MTech
- Identifier: http://hdl.handle.net/10948/42589 , vital:36670
- Description: Polypropylene (PP) is a semi crystalline thermoplastic polymer and one of the most commonly used polyolefins. It is well known for its poor impact resistance; hence, for industries such as the automotive and packaging, reinforced PP is widely used. In general plastic waste disposal is a global crisis raising environmental and human health concerns, with PP being the highest consumed polymer globally; hence a push in the reuse and recycling of PP. Recycled polypropylene has limited uses for industrial applications due to its highly reduced properties owing to the recycling process which inhabits cutting of chains lengths, broadened molecular weight distributions and compromised crystallinity. Several studies have investigated the use of reinforcing fillers and modifiers in order to improve properties of PP. Inorganic materials and minerals such as CaCO3, Mica, Talc and glass fibre are used as fillers to improve mechanical properties (tensile and hardness), but still lacks in improving the impact resistance. Thermoplastic elastomers (TPE) are typically used where elastomer and thermoplastics fail as individual components. This is because they have the benefit of thermoplastic properties at hypo ambient condition and elastomer properties such as good impact and elongation at sub-zero conditions. The study took a route of using PP and waste tyre crumb rubber (CR) material to prepare potentially low-cost waste based TPE’s, which would then inherit both properties of PP and the rubber component. VistamaxxTM 6202 (EPR), a commercial name for ethylene-propylene monomer (EPR), was used as a compatibiliser to improve interaction between PP and CR and to contribute towards the overall improvement of various properties such as mechanical properties. VistamaxxTM has a low glass transition temperature (Tg, = -30 ºC), which is important for low temperature applications such as cold storage; it also has a very high elongation and as a result contributed significantly to the overall properties when used in TPE blends. The study highlighted differences between two TPE compounding formulation pathways; namely master-batch (MB) and design of experiments (DoE). The MB formulations were blends that were prepared by a conventional way of compounding; where a pre-mixed CR/EPR blend, in the ratio of 80(CR):20(EPR), was used to form a master-batch. Results showed that there are some similarities between TPEs prepared in different ways, which suggests that the ultimate properties such as thermal stability are in fact more PP matrix based. Thermal analyses results revealed that when high amount of CR was added to the TPE blends, there was a substantial amount of residue mainly due to inherent carbon black. The degree of crystallinity of the blends decreased with increased amounts of CR irrespective of whether it was the MB or DoE blends. The MB TPE blends demonstrated that hardness is not linked to the amount of the MB nor the crystallinity of blends. Meanwhile, tensile elongation and tensile stress were affected by crystallinity. On the other hand, the impact strength findings showed that the amount of MB in TPE blends reached a threshold at 30%. The DoE based TPE blends demonstrated that the optimum mechanical properties are observed when components of the blends are incorporated individually during compounding. This was observed for impact strength, tensile stress as well as elongation at break. The results showed that the incorporation of EPR should be at least 20% for good impact and elongation properties; however, for tensile and hardness, the PP matrix must be high. The study also showed that, for better mechanical properties it was more suitable to use the blends formulated with DoE, because the master-batch approach limited the improving of the mechanical properties by an addition of up to 30% of both the CR and EPR. The storage modulus as well as the tan delta for both MB and DoE decreased when the elastomeric phases were added on both methods, whereas tan delta Tg values decreased as more of the elastomeric phase was added. Evidence from morphology studies showed that the majority of TPE blends suffer from inadequate distribution and adhesion between PP and elastomer; resulting in poor mechanical properties. Furthermore, a threshold of matrix invasion is observed from 30% and above of CR in the blend, where lack of in capsulated lamps of CR were observed hindering the stress induced crystallization and relaxation of the PP phase. The latter was observed irrespective of the type of blend, which strongly suggests and highlights the limits of blending PP with elastomers. Study demonstrated the ability of VistamaxxTM to be utilized as a binding material for PP and CR and displaying the challenges that might arise when used as a master-batch with crumb rubber.
- Full Text:
- Date Issued: 2019
Development of silver-based polyaniline nanocomposite for electrochemical oxidation and detection of organosulfur compounds
- Authors: Shoba, Siyabonga
- Date: 2019
- Subjects: Polyethylene -- Analysis , Composite materials Nanocomposites (Materials)
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/43600 , vital:36928
- Description: Human activities such as combustion of fossil fuels through automobiles, factories and electricity generation using coal results in major productions of sulfur dioxide to the atmosphere. The sulfur dioxide gas chemically reacts with other substances (i.e. water and oxygen) in the atmosphere and produces acidic pollutants. These acidic pollutants exist in both wet and dry form and before they are deposited on the earth’s surface, they can travel long distances carried by the wind. They are deposited in a wet form as rain, snow, fog and sleet and in a dry form as gases or particles. This has led to the mandated 10 ppm S in fuel by the environmental protection agency (EPA). Electrochemical desulfurization (ECDS) has been reported as an innovative technique for removing sulfur via redox processes. ECDS technique is a low costs process as no catalysts and oxidant are involved and it is a green technology (environmental benignity), thus making the process more economical than conventional hydrodesulfurization (HDS) technologies. Modification of electrodes for electrochemistry as well as electrodeposition of metal nanoparticles offers interesting electrochemical activities due to their reduced size and high surface area to volume ratio. Electrochemical oxidation of benzothiophene (BT), dibenzothiophene (DBT) and 4,6-dimethyldibenzothiophene (4,6-DMDBT) was analysed in acetonitrile using carbon electrodes modified with silver (Ag)-polyaniline (PAni) based nanocomposites (GCE/PAni/Ag and GCE/Ag). The PAni, PAni/Ag composites were characterized using spectroscopic (FT-IR, XRD, XPS) and microscopic (SEM and TEM) techniques. SEM confirmed that the synthesized PAni and PAni/Ag presented an amorphous granular morphology with the aggregation of small irregular particle sizes. Cyclic voltammetry of BT, DBT and 4,6-DMDBT on the modified glassy carbon (GCE) electrode show chemically irreversible anodic peaks which corresponds to electron transfer of sulfur to form sulfoxide and lastly sulfone containing compounds. The overall conversion yield of DBT and 4,6-DMDBT to respective sulfones increased as water content increases. Products were characterized by means of gas chromatograph coupled to mass spectrometer (GC-MS), 1H and 13C NMR. Similarly, silver-modified Glassy Carbon (GCE) electrode was used for the electrochemical detection of benzothiophene (BT), dibenzothiophene (DBT) and 4,6-dimethyldibenzothiophene (4,6-DMDBT) in the presence of naphthalene (NP) and carbazole (CR). The electrochemical response of BT, DBT and 4,6-DMDBT on the modified electrode was determined using Differential Pulse Voltammetry (DPV) in acetonitrile. The electrochemical behaviour of BT, DBT and 4,6-DMDBT showed that the modified electrode exhibited excellent oxidation electro-catalytic activity. The dynamic range for the organosulfur compounds determination was from 1 to 11 ppm with detection limits (LOD) of 0.60 ppmS, 0.41 ppmS and 0.21 ppmS for BT, DBT and 4,6-DMDBT, respectively. Electrochemical sensor showed excellent selectivity of the compounds in the presence of interfering compounds such as naphthalene, carbazole and thiourea over the studied range of concentrations. The prepared electrode exhibited satisfactory reusability and stability after four successive measurement. It has been demonstrated in this study that modified glassy carbon (GCE) electrode (GCE/PAni/Ag) can be successfully used for the assay of sulfur containing compounds such as BT, DBT and 4, 6-DMDBT in petroleum samples.
- Full Text:
- Date Issued: 2019
- Authors: Shoba, Siyabonga
- Date: 2019
- Subjects: Polyethylene -- Analysis , Composite materials Nanocomposites (Materials)
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/43600 , vital:36928
- Description: Human activities such as combustion of fossil fuels through automobiles, factories and electricity generation using coal results in major productions of sulfur dioxide to the atmosphere. The sulfur dioxide gas chemically reacts with other substances (i.e. water and oxygen) in the atmosphere and produces acidic pollutants. These acidic pollutants exist in both wet and dry form and before they are deposited on the earth’s surface, they can travel long distances carried by the wind. They are deposited in a wet form as rain, snow, fog and sleet and in a dry form as gases or particles. This has led to the mandated 10 ppm S in fuel by the environmental protection agency (EPA). Electrochemical desulfurization (ECDS) has been reported as an innovative technique for removing sulfur via redox processes. ECDS technique is a low costs process as no catalysts and oxidant are involved and it is a green technology (environmental benignity), thus making the process more economical than conventional hydrodesulfurization (HDS) technologies. Modification of electrodes for electrochemistry as well as electrodeposition of metal nanoparticles offers interesting electrochemical activities due to their reduced size and high surface area to volume ratio. Electrochemical oxidation of benzothiophene (BT), dibenzothiophene (DBT) and 4,6-dimethyldibenzothiophene (4,6-DMDBT) was analysed in acetonitrile using carbon electrodes modified with silver (Ag)-polyaniline (PAni) based nanocomposites (GCE/PAni/Ag and GCE/Ag). The PAni, PAni/Ag composites were characterized using spectroscopic (FT-IR, XRD, XPS) and microscopic (SEM and TEM) techniques. SEM confirmed that the synthesized PAni and PAni/Ag presented an amorphous granular morphology with the aggregation of small irregular particle sizes. Cyclic voltammetry of BT, DBT and 4,6-DMDBT on the modified glassy carbon (GCE) electrode show chemically irreversible anodic peaks which corresponds to electron transfer of sulfur to form sulfoxide and lastly sulfone containing compounds. The overall conversion yield of DBT and 4,6-DMDBT to respective sulfones increased as water content increases. Products were characterized by means of gas chromatograph coupled to mass spectrometer (GC-MS), 1H and 13C NMR. Similarly, silver-modified Glassy Carbon (GCE) electrode was used for the electrochemical detection of benzothiophene (BT), dibenzothiophene (DBT) and 4,6-dimethyldibenzothiophene (4,6-DMDBT) in the presence of naphthalene (NP) and carbazole (CR). The electrochemical response of BT, DBT and 4,6-DMDBT on the modified electrode was determined using Differential Pulse Voltammetry (DPV) in acetonitrile. The electrochemical behaviour of BT, DBT and 4,6-DMDBT showed that the modified electrode exhibited excellent oxidation electro-catalytic activity. The dynamic range for the organosulfur compounds determination was from 1 to 11 ppm with detection limits (LOD) of 0.60 ppmS, 0.41 ppmS and 0.21 ppmS for BT, DBT and 4,6-DMDBT, respectively. Electrochemical sensor showed excellent selectivity of the compounds in the presence of interfering compounds such as naphthalene, carbazole and thiourea over the studied range of concentrations. The prepared electrode exhibited satisfactory reusability and stability after four successive measurement. It has been demonstrated in this study that modified glassy carbon (GCE) electrode (GCE/PAni/Ag) can be successfully used for the assay of sulfur containing compounds such as BT, DBT and 4, 6-DMDBT in petroleum samples.
- Full Text:
- Date Issued: 2019
Development of spunlaced nonwoven filters from PAN, PPS and PI fibres for industrial use
- Authors: Maduna, Lebo
- Date: 2019
- Subjects: Textile fibers -- Mechanical properties , Nonwoven fabrics --Technological innovations Textile fibers, Synthetic -- Mechanical properties
- Language: English
- Type: Thesis , Doctoral , DPhil
- Identifier: http://hdl.handle.net/10948/32610 , vital:32266
- Description: The aim of this work was to produce filter fabrics suitable for high temperature and other conditions encountered in coal power plants using the spunlacing manufacturing technique. Polyacrylonitrile (PAN), polyphenylene sulfide (PPS) and polyimide (PI) fibres being combined suitable for this purpose, each at three aerial density of (440, 500 and 560 g/m2) and each at three water jet pressures of (60, 80 and 90 bars) were produced. The effect of changing these on the fabric air permeability, tensile strength and filtration properties were investigated and optimized. For this purpose, the Box-Behnken experimental design (BBD) was considered the best and therefore used. The PPS/PI fabrics were found to consistently have the highest air permeability, tensile strength and filtration performance, followed by the PPS fabrics and the PAN fabrics. As could be expected, an increase in area weight and water jet pressure generally resulted in a decrease in air permeability irrespective of the fabric types, this being due to the increased number of fibres and therefore greater fibre surface area and entanglement respectively. For fabric tensile strength, the effects of varying fabric area weight and water jet pressure were not so straight forward. For cross direction (CD) an increase in water jet pressure resulted in an increase tensile strength whereas in the machine direction (MD) there was a decrease when the water jet pressure was increased. The filtration efficiency and dust holding capacity of the fabrics were found to be around 96% and 211g/m2, respectively, with the exception of the PPS (500 g/m2 80 bar) fabrics. Increasing the amount of dust being fed to the fabric during each loading cycle, it caused an increase in pressure drop, as the fabrics became increasingly clogged forming a cake layer.
- Full Text:
- Date Issued: 2019
- Authors: Maduna, Lebo
- Date: 2019
- Subjects: Textile fibers -- Mechanical properties , Nonwoven fabrics --Technological innovations Textile fibers, Synthetic -- Mechanical properties
- Language: English
- Type: Thesis , Doctoral , DPhil
- Identifier: http://hdl.handle.net/10948/32610 , vital:32266
- Description: The aim of this work was to produce filter fabrics suitable for high temperature and other conditions encountered in coal power plants using the spunlacing manufacturing technique. Polyacrylonitrile (PAN), polyphenylene sulfide (PPS) and polyimide (PI) fibres being combined suitable for this purpose, each at three aerial density of (440, 500 and 560 g/m2) and each at three water jet pressures of (60, 80 and 90 bars) were produced. The effect of changing these on the fabric air permeability, tensile strength and filtration properties were investigated and optimized. For this purpose, the Box-Behnken experimental design (BBD) was considered the best and therefore used. The PPS/PI fabrics were found to consistently have the highest air permeability, tensile strength and filtration performance, followed by the PPS fabrics and the PAN fabrics. As could be expected, an increase in area weight and water jet pressure generally resulted in a decrease in air permeability irrespective of the fabric types, this being due to the increased number of fibres and therefore greater fibre surface area and entanglement respectively. For fabric tensile strength, the effects of varying fabric area weight and water jet pressure were not so straight forward. For cross direction (CD) an increase in water jet pressure resulted in an increase tensile strength whereas in the machine direction (MD) there was a decrease when the water jet pressure was increased. The filtration efficiency and dust holding capacity of the fabrics were found to be around 96% and 211g/m2, respectively, with the exception of the PPS (500 g/m2 80 bar) fabrics. Increasing the amount of dust being fed to the fabric during each loading cycle, it caused an increase in pressure drop, as the fabrics became increasingly clogged forming a cake layer.
- Full Text:
- Date Issued: 2019
Development of titanium dioxide for photo-electrochemical hydrogen production
- Authors: Mbulanga, Crispin Munyelele
- Date: 2019
- Subjects: Titanium dioxide , Nanostructured materials Water chemistry Environmental chemistry
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10948/40735 , vital:36231
- Description: TiO2 is an attractive material for photo electrochemical hydrogen production and in this work the synthesis of this compound by hydrothermal, gel-calcination and one-step templating methods is investigated. Rutile-phase TiO2 rods, which are known to offer direct electrical pathways for photo generated electrons when using TiO2 as a photo anode in a photo-electrochemical hydrogen cell, were prepared on both F:SnO2 (FTO) coated glass and Ti foil substrates. Anatase-phase TiO2 tubes and mixed rutile-anatase-phase TiO2 nanostructured films were developed on FTO-coated glass substrates. Rutile-phase TiO2 rod-like structures, were synthesized hydrothermally at 150 oC for different times (6 – 20 hours) on FTO-coated glass substrate, in an aqueous solution of hydrochloric acid and titanium butoxide. The rod-like structures were found to comprise bundles of crystalline prismatic TiO2 nanorods, each approximately 4 nm in width. Each bundle was tetragonal in shape and highly oriented with respect to the substrate surface. The average diameter of the bundles varied depending on the growth time, and reached a mean diameter of ~175 nm after 20 hours of growth. In terms of Raman scattering, these bundles of nanorods acted as single entities, appearing to act as “larger” crystals to the lattice phonons. Hence, phonon confinement effects could not be observed, because the translational symmetry is preserved at the boundaries between individual rods. Moreover, as the preferential perpendicular orientation of the bundles improved with growth time, an unusual increase in the room and low (77K) temperature Eg/A1g Raman band intensity ratios was observed. The low temperature Raman peak position and peak width data was interpreted as supporting the hypothesis that the bundles of nanorods acting as single entities from the point of view of the lattice phonons. The phonon symmetries and frequencies (in cm-1) of these bundles of rutile-phase TiO2 were found to be consistent with rutile-phase TiO2 phonon symmetries and frequencies. Rutile-phase TiO2 rod-like structures were prepared on Ti foil following a two-step gel-calcination method, which involves a gel-deposition process in 5 M NaOH solution at 76 oC for 24 hours to produce a Na- (and Ti-) based layer of gelatinous material, followed by calcination at 600 oC or 800 oC for 1 hour. It is shown that the use of an alkali-based solution such as NaOH and KOH during gel-deposition, leads to the formation of faceted nanorods of rutile-phase TiO2 upon calcination at high temperature. When a solution that does not contain any alkali element, such as H2O2, was used, the material formed upon calcination at 800 oC were clustered nanoparticles, rather than nanorods. From the experiments it was deduced that the high temperature calcination step converted the Na(or K)-based amorphous gel (formed on the Ti surface during a 24-h soak in NaOH (KOH) solution) into faceted Na-titanate rods, which converted into nanorods of rutile-phase TiO2 when Na(or K) evaporates in the form of an oxide. Anatase-phase TiO2 tube-like structures were produced by a one-step templating solution approach, on FTO-coated glass substrate. ZnO nanorod templates were prepared by chemical bath deposition on FTO-coated glass substrate, and then treated in an aqueous mixture of ammonium hexafluorotitanate and boric acid. To study the effect of the template morphology and deposition processes on the formation of anatase TiO2 tubes, different times (10 – 60 minutes) and concentrations of the precursors are used. Calcination at 550 oC converted the Ti-based material developed on the ZnO rods into TiO2 nanostructures. A 10 minute deposition yielded tubes with dimensions resembling those of the ZnO template. However, the tube walls still contained Zn traces. Based on experimental observations, it was concluded that the production of titanium hydroxide complexes on ZnO surfaces takes place through two competing processes: the development of a Ti-based material and partial dissolution of ZnO along the c-axis. Calcination at 550 oC in air finally yielded anatase TiO2. Mixed rutile-anatase-phase TiO2 nanostructured films on FTO-coated glass substrate were prepared by decorating bundles of crystalline prismatic TiO2 nanorods (prepared hydrothermally) with anatase-phase TiO2 particles, using the same precursors mentioned above. The effect of reaction time and precursor concentrations were investigated. It was found that the precursor concentration ratio and reaction time played key roles in controlling the decoration process. Optimal ratios and decoration times were established based on the density of anatase-phase TiO2 decorating particles on the surface of bundles of rutile-phase TiO2 nanorods. The optical properties of rutile-phase TiO2 rods were investigated. The thickness of the TiO2 layer was calculated from reflectance fringes, and agreed well with the length of rods observed using SEM. The room temperature absorption edge of Eg=2.90 eV extracted from the transmittance spectrum correlated with typical values reported for TiO2. The room temperature absorption edge of the conductive layer of F:SnO2 (Eg=3.56 eV) could also be extracted from the transmittance spectrum. Finally, the absorption of white light by rutile-phase TiO2 rods was confirmed to be enhanced by annealing the rods in either hydrogen or nitrogen at 600 oC. Defects (possibly oxygen vacancies) or disorder in the near surface layers of TiO2 induced during the reduction experiments, created new electronic states in the band gap, as reported in literature.
- Full Text:
- Date Issued: 2019
- Authors: Mbulanga, Crispin Munyelele
- Date: 2019
- Subjects: Titanium dioxide , Nanostructured materials Water chemistry Environmental chemistry
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10948/40735 , vital:36231
- Description: TiO2 is an attractive material for photo electrochemical hydrogen production and in this work the synthesis of this compound by hydrothermal, gel-calcination and one-step templating methods is investigated. Rutile-phase TiO2 rods, which are known to offer direct electrical pathways for photo generated electrons when using TiO2 as a photo anode in a photo-electrochemical hydrogen cell, were prepared on both F:SnO2 (FTO) coated glass and Ti foil substrates. Anatase-phase TiO2 tubes and mixed rutile-anatase-phase TiO2 nanostructured films were developed on FTO-coated glass substrates. Rutile-phase TiO2 rod-like structures, were synthesized hydrothermally at 150 oC for different times (6 – 20 hours) on FTO-coated glass substrate, in an aqueous solution of hydrochloric acid and titanium butoxide. The rod-like structures were found to comprise bundles of crystalline prismatic TiO2 nanorods, each approximately 4 nm in width. Each bundle was tetragonal in shape and highly oriented with respect to the substrate surface. The average diameter of the bundles varied depending on the growth time, and reached a mean diameter of ~175 nm after 20 hours of growth. In terms of Raman scattering, these bundles of nanorods acted as single entities, appearing to act as “larger” crystals to the lattice phonons. Hence, phonon confinement effects could not be observed, because the translational symmetry is preserved at the boundaries between individual rods. Moreover, as the preferential perpendicular orientation of the bundles improved with growth time, an unusual increase in the room and low (77K) temperature Eg/A1g Raman band intensity ratios was observed. The low temperature Raman peak position and peak width data was interpreted as supporting the hypothesis that the bundles of nanorods acting as single entities from the point of view of the lattice phonons. The phonon symmetries and frequencies (in cm-1) of these bundles of rutile-phase TiO2 were found to be consistent with rutile-phase TiO2 phonon symmetries and frequencies. Rutile-phase TiO2 rod-like structures were prepared on Ti foil following a two-step gel-calcination method, which involves a gel-deposition process in 5 M NaOH solution at 76 oC for 24 hours to produce a Na- (and Ti-) based layer of gelatinous material, followed by calcination at 600 oC or 800 oC for 1 hour. It is shown that the use of an alkali-based solution such as NaOH and KOH during gel-deposition, leads to the formation of faceted nanorods of rutile-phase TiO2 upon calcination at high temperature. When a solution that does not contain any alkali element, such as H2O2, was used, the material formed upon calcination at 800 oC were clustered nanoparticles, rather than nanorods. From the experiments it was deduced that the high temperature calcination step converted the Na(or K)-based amorphous gel (formed on the Ti surface during a 24-h soak in NaOH (KOH) solution) into faceted Na-titanate rods, which converted into nanorods of rutile-phase TiO2 when Na(or K) evaporates in the form of an oxide. Anatase-phase TiO2 tube-like structures were produced by a one-step templating solution approach, on FTO-coated glass substrate. ZnO nanorod templates were prepared by chemical bath deposition on FTO-coated glass substrate, and then treated in an aqueous mixture of ammonium hexafluorotitanate and boric acid. To study the effect of the template morphology and deposition processes on the formation of anatase TiO2 tubes, different times (10 – 60 minutes) and concentrations of the precursors are used. Calcination at 550 oC converted the Ti-based material developed on the ZnO rods into TiO2 nanostructures. A 10 minute deposition yielded tubes with dimensions resembling those of the ZnO template. However, the tube walls still contained Zn traces. Based on experimental observations, it was concluded that the production of titanium hydroxide complexes on ZnO surfaces takes place through two competing processes: the development of a Ti-based material and partial dissolution of ZnO along the c-axis. Calcination at 550 oC in air finally yielded anatase TiO2. Mixed rutile-anatase-phase TiO2 nanostructured films on FTO-coated glass substrate were prepared by decorating bundles of crystalline prismatic TiO2 nanorods (prepared hydrothermally) with anatase-phase TiO2 particles, using the same precursors mentioned above. The effect of reaction time and precursor concentrations were investigated. It was found that the precursor concentration ratio and reaction time played key roles in controlling the decoration process. Optimal ratios and decoration times were established based on the density of anatase-phase TiO2 decorating particles on the surface of bundles of rutile-phase TiO2 nanorods. The optical properties of rutile-phase TiO2 rods were investigated. The thickness of the TiO2 layer was calculated from reflectance fringes, and agreed well with the length of rods observed using SEM. The room temperature absorption edge of Eg=2.90 eV extracted from the transmittance spectrum correlated with typical values reported for TiO2. The room temperature absorption edge of the conductive layer of F:SnO2 (Eg=3.56 eV) could also be extracted from the transmittance spectrum. Finally, the absorption of white light by rutile-phase TiO2 rods was confirmed to be enhanced by annealing the rods in either hydrogen or nitrogen at 600 oC. Defects (possibly oxygen vacancies) or disorder in the near surface layers of TiO2 induced during the reduction experiments, created new electronic states in the band gap, as reported in literature.
- Full Text:
- Date Issued: 2019
Development, manufacture and characterization of niosomes for the delivery for nevirapine
- Witika, Bwalya A, Walker, Roderick B
- Authors: Witika, Bwalya A , Walker, Roderick B
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/183514 , vital:44002 , xlink:href="https://doi.org/10.1691/ph.2019.8168"
- Description: Nevirapine (NVP), used for the treatment of HIV/AIDS, exhibits unpredictable oral bioavailability, has a poor side effect profile and requires frequent dosing. Niosomes are novel drug delivery systems that have the potential to overcome these challenges. A thin layer hydration approach was used to produce niosomes and optimisation was undertaken using design of experiments (DoE) and response surface methodology (RSM) establish and identify parameters that may affect the manufacture of niosomes. The impact of cholesterol and surfactant content, hydration time and temperature on manufacture was investigated. Critical quality attributes (CQA) in respect of particle size (PS), entrapment efficiency (EE), polydispersity index (PDI) and the amount of NVP released at 48 hours was also assessed. The optimised niosome composition was identified and manufactured and the CQA characterised prior to placing the batch on stability for 12 weeks at 4±2 °C and 22±2 °C. The PS, PDI, EE and % NVP released at 48 h was 523.36±23.16 nm, 0.386±0.054, 96.8 % and 25.3 % for niosomes manufactured with Span® 20. Similarly, the parameters were 502.87±21.77 nm and 0.394±0.027, 98.0 % and 25.0 % for mean PS, PDI, EE and %NVP released at 48 h for Span® 80 niosomes. All characterisation was undertaken on the day of manufacture. In conclusion, a simple, cheap, rapid and precise method of manufacture of NVP niosomes was developed, validated and optimised using DoE and RSM and the product exhibited the target CQA.
- Full Text:
- Date Issued: 2019
- Authors: Witika, Bwalya A , Walker, Roderick B
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/183514 , vital:44002 , xlink:href="https://doi.org/10.1691/ph.2019.8168"
- Description: Nevirapine (NVP), used for the treatment of HIV/AIDS, exhibits unpredictable oral bioavailability, has a poor side effect profile and requires frequent dosing. Niosomes are novel drug delivery systems that have the potential to overcome these challenges. A thin layer hydration approach was used to produce niosomes and optimisation was undertaken using design of experiments (DoE) and response surface methodology (RSM) establish and identify parameters that may affect the manufacture of niosomes. The impact of cholesterol and surfactant content, hydration time and temperature on manufacture was investigated. Critical quality attributes (CQA) in respect of particle size (PS), entrapment efficiency (EE), polydispersity index (PDI) and the amount of NVP released at 48 hours was also assessed. The optimised niosome composition was identified and manufactured and the CQA characterised prior to placing the batch on stability for 12 weeks at 4±2 °C and 22±2 °C. The PS, PDI, EE and % NVP released at 48 h was 523.36±23.16 nm, 0.386±0.054, 96.8 % and 25.3 % for niosomes manufactured with Span® 20. Similarly, the parameters were 502.87±21.77 nm and 0.394±0.027, 98.0 % and 25.0 % for mean PS, PDI, EE and %NVP released at 48 h for Span® 80 niosomes. All characterisation was undertaken on the day of manufacture. In conclusion, a simple, cheap, rapid and precise method of manufacture of NVP niosomes was developed, validated and optimised using DoE and RSM and the product exhibited the target CQA.
- Full Text:
- Date Issued: 2019
Devulcanisation of truck tyre tread vulcanisates in supercritical carbon dioxide using diphenyl disulphide and 2,2- dithiobis(benzothiazole)
- Mabuto, Briswell, Ogunlanja, A
- Authors: Mabuto, Briswell , Ogunlanja, A
- Date: 2019
- Subjects: Vulcanization , Polymeric composites Rubber Carbon dioxide -- Thermal properties Environmental chemistry
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/40702 , vital:36224
- Description: A lot of work has been done in the recycling industry in an effort to increase the amount of reclaimed rubber used in new tyre formulations. The major drawback has been inferior physical and mechanical properties of reclaimed/virgin rubber blends in comparison to the virgin rubber material. Deterioration in these properties has been identified to be a result of chain degradation during reclamation processes as well as presence of crosslinks in the final reclaim product. Devulcanisation techniques have gained precedence due to the relatively improved properties of devulcanised/virgin rubber blends. The concept of devulcanisation is to reverse vulcanisation, resulting in total or partial cleavage of crosslinks. In this way, chain degradation is minimised while crosslink scission is maximised, thereby resulting in good quality devulcanised rubber. However, due to the persistence of chain degradation and crosslinks during devulcanisation processes, a very limited number of reports have claimed success in achieving this goal. Therefore there is still the need to develop a devulcanisation method that ensures improved quality and productivity of devulcanised rubber. Typical truck tyre tread vulcanisates were used for optimisation of time, temperature, heating rate, pressure and amount of devulcanising agent while monitoring percentage devulcanisation in supercritical carbon dioxide medium. Optimisation of the devulcanisation conditions was done by employing a twolevel central composite design in the isothermal and non-isothermal heating stages. This was followed by a single factor analysis of devulcanisation conditions in the non-isothermal stage. The effect of the presence of carbon black was investigated by comparing the percentage devulcanisation of carbon black filled and unfilled samples. The results show that supercritical carbon dioxide is an effective medium of devulcanisation using diphenyl disulphide (DD) and 2,2-dithiobis(benzothiazole) (MBTS). The relatively higher degree of devulcanisation observed during the non-isothermal stage compared to the isothermal stage, led to a shift of focus to non-isothermal devulcanisation. Temperature and time were found to have a significant antagonistic effect on the percentage devulcanisation, while changes in pressure above critical point and mass of devulcanising agent showed no effect on percentage devulcanisation. The heating rate was determined by the set-point, of which 180 ℃ set-point temperature resulted in desirable degree of devulcanisation for both DD and MBTS. 76.18 ± 5.50 % devulcanisation in 5 minutes at 102 ℃ was observed for DD whilst 70.92 ± 4.10 % devulcanisation in 4 minutes at 97 ℃ was observed for MBTS. Changes in pressure above critical point and mass of devulcanising agent used in devulcanisation showed no significant effect in the percentage devulcanisation and so they were kept constant at 80 bars and 1.00 % v (of weight of rubber sample) devulcanisation agent, respectively. The presence of carbon black was found to have an effect on the degree of devulcanisation; 87.95 % and 81.33 % devulcanisation was observed for unfilled samples devulcanised using DD and MBTS respectively. Thermogravimetric analysis of the natural rubber/styrene butadiene rubber (NR/SBR respectively) relative composition of devulcanisates indicated uneven devulcanisation when using DD, whereas MBTS did not show any form of preference. DD showed preference for NR devulcanisation over SBR. Further analysis of the sol and gel fractions were performed using; Differential Scanning Calorimetry, Fourier Transform Infrared Spectroscopy, Gel Permeation Chromatography and Gas Chromatography coupled with Mass Spectroscopy. Application of the optimised conditions to devulcanise ground tyre rubber (GTR) resulted in relatively lower degrees of devulcanisation for both DD and MBTS; 41.22 ± 4.22 and 22.41 ± 1.97 respectively. The differences in the degree of devulcanisation of the laboratory prepared vulcanisates and the GTR was determined to be due to sample differences; i.e. sample constituents, particle dimensions and crosslink network (crosslink distribution in particular).
- Full Text:
- Date Issued: 2019
- Authors: Mabuto, Briswell , Ogunlanja, A
- Date: 2019
- Subjects: Vulcanization , Polymeric composites Rubber Carbon dioxide -- Thermal properties Environmental chemistry
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/40702 , vital:36224
- Description: A lot of work has been done in the recycling industry in an effort to increase the amount of reclaimed rubber used in new tyre formulations. The major drawback has been inferior physical and mechanical properties of reclaimed/virgin rubber blends in comparison to the virgin rubber material. Deterioration in these properties has been identified to be a result of chain degradation during reclamation processes as well as presence of crosslinks in the final reclaim product. Devulcanisation techniques have gained precedence due to the relatively improved properties of devulcanised/virgin rubber blends. The concept of devulcanisation is to reverse vulcanisation, resulting in total or partial cleavage of crosslinks. In this way, chain degradation is minimised while crosslink scission is maximised, thereby resulting in good quality devulcanised rubber. However, due to the persistence of chain degradation and crosslinks during devulcanisation processes, a very limited number of reports have claimed success in achieving this goal. Therefore there is still the need to develop a devulcanisation method that ensures improved quality and productivity of devulcanised rubber. Typical truck tyre tread vulcanisates were used for optimisation of time, temperature, heating rate, pressure and amount of devulcanising agent while monitoring percentage devulcanisation in supercritical carbon dioxide medium. Optimisation of the devulcanisation conditions was done by employing a twolevel central composite design in the isothermal and non-isothermal heating stages. This was followed by a single factor analysis of devulcanisation conditions in the non-isothermal stage. The effect of the presence of carbon black was investigated by comparing the percentage devulcanisation of carbon black filled and unfilled samples. The results show that supercritical carbon dioxide is an effective medium of devulcanisation using diphenyl disulphide (DD) and 2,2-dithiobis(benzothiazole) (MBTS). The relatively higher degree of devulcanisation observed during the non-isothermal stage compared to the isothermal stage, led to a shift of focus to non-isothermal devulcanisation. Temperature and time were found to have a significant antagonistic effect on the percentage devulcanisation, while changes in pressure above critical point and mass of devulcanising agent showed no effect on percentage devulcanisation. The heating rate was determined by the set-point, of which 180 ℃ set-point temperature resulted in desirable degree of devulcanisation for both DD and MBTS. 76.18 ± 5.50 % devulcanisation in 5 minutes at 102 ℃ was observed for DD whilst 70.92 ± 4.10 % devulcanisation in 4 minutes at 97 ℃ was observed for MBTS. Changes in pressure above critical point and mass of devulcanising agent used in devulcanisation showed no significant effect in the percentage devulcanisation and so they were kept constant at 80 bars and 1.00 % v (of weight of rubber sample) devulcanisation agent, respectively. The presence of carbon black was found to have an effect on the degree of devulcanisation; 87.95 % and 81.33 % devulcanisation was observed for unfilled samples devulcanised using DD and MBTS respectively. Thermogravimetric analysis of the natural rubber/styrene butadiene rubber (NR/SBR respectively) relative composition of devulcanisates indicated uneven devulcanisation when using DD, whereas MBTS did not show any form of preference. DD showed preference for NR devulcanisation over SBR. Further analysis of the sol and gel fractions were performed using; Differential Scanning Calorimetry, Fourier Transform Infrared Spectroscopy, Gel Permeation Chromatography and Gas Chromatography coupled with Mass Spectroscopy. Application of the optimised conditions to devulcanise ground tyre rubber (GTR) resulted in relatively lower degrees of devulcanisation for both DD and MBTS; 41.22 ± 4.22 and 22.41 ± 1.97 respectively. The differences in the degree of devulcanisation of the laboratory prepared vulcanisates and the GTR was determined to be due to sample differences; i.e. sample constituents, particle dimensions and crosslink network (crosslink distribution in particular).
- Full Text:
- Date Issued: 2019
Differences in the use of surface water resources by desert birds are revealed using isotopic tracers
- Smit, Ben, Woodborne, Stephan, Wolf, Blair O, McKechnie, Andrew E
- Authors: Smit, Ben , Woodborne, Stephan , Wolf, Blair O , McKechnie, Andrew E
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/440532 , vital:73790 , https://doi.org/10.1093/auk/uky005
- Description: The scarcity of free-standing water sources is a key determinant of animal and plant community structure in arid environments, and an understanding of the extent to which particular species use surface water is vital for modeling the effects of climate change on desert avifauna. We investigated interspecific variation in the use of artificial water sources among birds in the Kalahari Desert, South Africa, by (i) observations at waterholes and (ii) tracing spatial water-use patterns during summer by isotopically labeled water sources and blood sampling. More than 50% of the avian community (primarily insectivores and omnivores) were not observed to drink. The majority (53%) of species drinking at waterholes were granivorous, and their use of surface water was best predicted by their relative abundance in the community. Species representing the remaining dietary guilds drank significantly more on hot days. Blood samples revealed that only 11 of 42 species (mostly granivores and a few omnivores) showed evidence of drinking at a waterhole with enriched deuterium values; on average, in the latter birds, water from the enriched waterhole accounted for ~38% of their body water pool. These findings illustrate that 2 methods employed in this study provide different, but complementary data on the relative importance of a water source for an avian community. Although our results suggest that most avian species are independent of surface water, drinking patterns on the hottest days during our study period suggest that free-standing water might become more important for some of the non-drinking species under hotter climatic conditions.
- Full Text:
- Date Issued: 2019
- Authors: Smit, Ben , Woodborne, Stephan , Wolf, Blair O , McKechnie, Andrew E
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/440532 , vital:73790 , https://doi.org/10.1093/auk/uky005
- Description: The scarcity of free-standing water sources is a key determinant of animal and plant community structure in arid environments, and an understanding of the extent to which particular species use surface water is vital for modeling the effects of climate change on desert avifauna. We investigated interspecific variation in the use of artificial water sources among birds in the Kalahari Desert, South Africa, by (i) observations at waterholes and (ii) tracing spatial water-use patterns during summer by isotopically labeled water sources and blood sampling. More than 50% of the avian community (primarily insectivores and omnivores) were not observed to drink. The majority (53%) of species drinking at waterholes were granivorous, and their use of surface water was best predicted by their relative abundance in the community. Species representing the remaining dietary guilds drank significantly more on hot days. Blood samples revealed that only 11 of 42 species (mostly granivores and a few omnivores) showed evidence of drinking at a waterhole with enriched deuterium values; on average, in the latter birds, water from the enriched waterhole accounted for ~38% of their body water pool. These findings illustrate that 2 methods employed in this study provide different, but complementary data on the relative importance of a water source for an avian community. Although our results suggest that most avian species are independent of surface water, drinking patterns on the hottest days during our study period suggest that free-standing water might become more important for some of the non-drinking species under hotter climatic conditions.
- Full Text:
- Date Issued: 2019
Differentiated Instruction: A Study of English Second Language Teachers’ Awareness and Implementation in Selected High Schools in the Eastern Cape Province
- Authors: Ndu, Onyinyechi Glory
- Date: 2019
- Subjects: English language -- Study and teaching Language and languages -- Study and teaching
- Language: English
- Type: Thesis , Doctoral , D Lit. (English)
- Identifier: http://hdl.handle.net/10353/11440 , vital:39072
- Description: The lack of visible academic excellence in South Africa has necessitated the search for a more in-depth approach in teaching and learning. The Department of Basic Education, school administrators and School Governing Bodies are not left out in the search for a distinct approach that would be able to assist teachers and also accommodate diverse learning abilities found in the classroom. The purpose of this study is to investigate English Second Language teachers’ awareness and implementation of differentiated instruction in selected high schools in the Eastern Cape Province, South Africa. The objectives were to find out the extent to which teachers adopt differentiated instructions in their classes: to examine teachers’ narratives about differentiated instruction and the alternative instruction teachers’ use in their classrooms. The study was anchored on the socio-cultural theory, multiple intelligence theory and learning style theory. It employed a mixed method research and triangulation, which was very beneficial for the validation of the research findings. It followed a case study exploratory design and descriptive survey design. A purposive sample of hundred and six (106) participants were used in the study. The quantitative data were analysed using tables, frequencies and percentages while the qualitative data were analysed thematically. The findings of the study revealed that ESL Grade 10 high school teachers were not aware of the term “Differentiated Instruction” even though to some extent they adopted DI approach. Teachers had mixed narratives about DI implementation and they used different alternative instructions during their lessons. The researcher recommended that teachers should be introduced to DI approach and be given more assistance, motivation, exposure and trainings in the form of conferences and seminars on proper DI implementation. Also teachers should be encouraged to continuously develop themselves academically in order to adjust to the new trend of managing the diverse learners that exist in their classes and in differentiating instruction with technology.
- Full Text:
- Date Issued: 2019
- Authors: Ndu, Onyinyechi Glory
- Date: 2019
- Subjects: English language -- Study and teaching Language and languages -- Study and teaching
- Language: English
- Type: Thesis , Doctoral , D Lit. (English)
- Identifier: http://hdl.handle.net/10353/11440 , vital:39072
- Description: The lack of visible academic excellence in South Africa has necessitated the search for a more in-depth approach in teaching and learning. The Department of Basic Education, school administrators and School Governing Bodies are not left out in the search for a distinct approach that would be able to assist teachers and also accommodate diverse learning abilities found in the classroom. The purpose of this study is to investigate English Second Language teachers’ awareness and implementation of differentiated instruction in selected high schools in the Eastern Cape Province, South Africa. The objectives were to find out the extent to which teachers adopt differentiated instructions in their classes: to examine teachers’ narratives about differentiated instruction and the alternative instruction teachers’ use in their classrooms. The study was anchored on the socio-cultural theory, multiple intelligence theory and learning style theory. It employed a mixed method research and triangulation, which was very beneficial for the validation of the research findings. It followed a case study exploratory design and descriptive survey design. A purposive sample of hundred and six (106) participants were used in the study. The quantitative data were analysed using tables, frequencies and percentages while the qualitative data were analysed thematically. The findings of the study revealed that ESL Grade 10 high school teachers were not aware of the term “Differentiated Instruction” even though to some extent they adopted DI approach. Teachers had mixed narratives about DI implementation and they used different alternative instructions during their lessons. The researcher recommended that teachers should be introduced to DI approach and be given more assistance, motivation, exposure and trainings in the form of conferences and seminars on proper DI implementation. Also teachers should be encouraged to continuously develop themselves academically in order to adjust to the new trend of managing the diverse learners that exist in their classes and in differentiating instruction with technology.
- Full Text:
- Date Issued: 2019
Digital colonialism: South Africa’s education transformation in the shadow of Silicon Valley
- Authors: Kwet, Michael
- Date: 2019
- Subjects: Operation Phakisa Education (South Africa) , Educational technology -- South Africa , Internet in education -- South Africa , Educational sociology -- South Africa , Technological innovations -- South Africa , Technological literacy -- South Africa , Education and state -- South Africa , Open source software -- South Africa , Electronic surveillance -- Social aspects -- South Africa , Privacy, Right of -- South Africa , Business and education -- South Africa
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/93767 , vital:30936
- Description: This dissertation investigates the social implications of technology choices for the emerging education transformation of the South African basic education sector. In October 2015, then President Jacob Zuma launched Operation Phakisa Education (OPE), an initiative designed behind closed doors to fast-track digital education into all South African public schools. This study identifies and analyses policy choices and perspectives regarding the technology considered and deployed for the national education rollout. It documents the OPE proposal, and examines how e-education policy choices relate to humanitarian objectives. Theoretically, this study draws upon libertarian socialist theory (anarchism) to examine the sociology of education technology policy. Using anarchist theory, it assesses the perspective, aims, and choices of e-education policy at the national level. It also draws on the Free Software philosophy for society as articulated by Richard Stallman and Eben Moglen. Finally, it compares classic colonialism with global power in the digital era, and posits a theory of digital colonialism. Synthesizing anarchism and the Free Software philosophy into a single theoretical framework – placed into the context of colonial relations – it is the first work to apply anarchist sociological theory to education technology policy, and the first doctoral study on digital colonialism. For its methodology, this dissertation utilizes two qualitative methods: document analysis and semi-structured interviews. Interview subjects include high-level e-education policymakers and administrators in government, key stakeholders, and experts at the intersection of technology innovation and human rights. These methods were used to both identify and interrogate e-education policy as it relates to the humanitarian objectives of education policy at the national level. The findings demonstrate that South African education policy is beholden to largely United States-based corporations and models for e-education. The study found that the types of technologies for consideration in education are rooted in surveillance capitalism, which is spreading across the world. It contends that current e-education policy choices will entrench the power and exploitation of US state-corporate power in South African education, economy, and society. It argues that an alternative set of choices, People’s Technology for People’s Power, is consistent with the spirit of South African technology policy, and should be chosen for South African schools in order to counter the power of foreign power and resist surveillance capitalism. This dissertation is the first publication to document and analyze what the new government education policy is about and how it relates to equality and human rights. It argues that present South African e-education policy constitutes a new form of digitally-driven technocratic neoliberalism which ultimately favors ruling class interests in the United States and South Africa. It also argues that OPE violates South Africa’s Free and Open Source policy and the spirit of democracy outlined in the Phakisa methodology and the Batho Pele principles. This study found that OPE replicates the latest trends in e-education implementation popular in Silicon Valley. Tech multinationals are providing both the products and models for use in South Africa. The dissertation concludes that US technological and conceptual dominance in South African education constitutes digital colonialism. It emphasizes the need for public inclusion in the policy process, and proposes alternative policies and technologies for e-education based on the idea of People’s Technology for People’s Power. It also argues that current scholarship on education technology neglects the political and sociological importance of People’s Technology to education, economy, and society, as well as the global significance of Big Tech dominance vis-a-vis digital colonialism, and that subsequent literature would be enriched by addressing these issues.
- Full Text:
- Date Issued: 2019
- Authors: Kwet, Michael
- Date: 2019
- Subjects: Operation Phakisa Education (South Africa) , Educational technology -- South Africa , Internet in education -- South Africa , Educational sociology -- South Africa , Technological innovations -- South Africa , Technological literacy -- South Africa , Education and state -- South Africa , Open source software -- South Africa , Electronic surveillance -- Social aspects -- South Africa , Privacy, Right of -- South Africa , Business and education -- South Africa
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/93767 , vital:30936
- Description: This dissertation investigates the social implications of technology choices for the emerging education transformation of the South African basic education sector. In October 2015, then President Jacob Zuma launched Operation Phakisa Education (OPE), an initiative designed behind closed doors to fast-track digital education into all South African public schools. This study identifies and analyses policy choices and perspectives regarding the technology considered and deployed for the national education rollout. It documents the OPE proposal, and examines how e-education policy choices relate to humanitarian objectives. Theoretically, this study draws upon libertarian socialist theory (anarchism) to examine the sociology of education technology policy. Using anarchist theory, it assesses the perspective, aims, and choices of e-education policy at the national level. It also draws on the Free Software philosophy for society as articulated by Richard Stallman and Eben Moglen. Finally, it compares classic colonialism with global power in the digital era, and posits a theory of digital colonialism. Synthesizing anarchism and the Free Software philosophy into a single theoretical framework – placed into the context of colonial relations – it is the first work to apply anarchist sociological theory to education technology policy, and the first doctoral study on digital colonialism. For its methodology, this dissertation utilizes two qualitative methods: document analysis and semi-structured interviews. Interview subjects include high-level e-education policymakers and administrators in government, key stakeholders, and experts at the intersection of technology innovation and human rights. These methods were used to both identify and interrogate e-education policy as it relates to the humanitarian objectives of education policy at the national level. The findings demonstrate that South African education policy is beholden to largely United States-based corporations and models for e-education. The study found that the types of technologies for consideration in education are rooted in surveillance capitalism, which is spreading across the world. It contends that current e-education policy choices will entrench the power and exploitation of US state-corporate power in South African education, economy, and society. It argues that an alternative set of choices, People’s Technology for People’s Power, is consistent with the spirit of South African technology policy, and should be chosen for South African schools in order to counter the power of foreign power and resist surveillance capitalism. This dissertation is the first publication to document and analyze what the new government education policy is about and how it relates to equality and human rights. It argues that present South African e-education policy constitutes a new form of digitally-driven technocratic neoliberalism which ultimately favors ruling class interests in the United States and South Africa. It also argues that OPE violates South Africa’s Free and Open Source policy and the spirit of democracy outlined in the Phakisa methodology and the Batho Pele principles. This study found that OPE replicates the latest trends in e-education implementation popular in Silicon Valley. Tech multinationals are providing both the products and models for use in South Africa. The dissertation concludes that US technological and conceptual dominance in South African education constitutes digital colonialism. It emphasizes the need for public inclusion in the policy process, and proposes alternative policies and technologies for e-education based on the idea of People’s Technology for People’s Power. It also argues that current scholarship on education technology neglects the political and sociological importance of People’s Technology to education, economy, and society, as well as the global significance of Big Tech dominance vis-a-vis digital colonialism, and that subsequent literature would be enriched by addressing these issues.
- Full Text:
- Date Issued: 2019
Discorhabdin N, a South African Natural Compound, for Hsp72 and Hsc70 Allosteric Modulation: combined study of molecular modeling and dynamic residue network analysis
- Amusengeri, Arnold, Tastan Bishop, Özlem
- Authors: Amusengeri, Arnold , Tastan Bishop, Özlem
- Date: 2019
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/162949 , vital:40999 , https://doi.org/10.3390/molecules24010188
- Description: The human heat shock proteins (Hsps), predominantly Hsp72 and Hsp90, have been strongly implicated in various critical stages of oncogenesis and progression of human cancers. While drug development has extensively focused on Hsp90 as a potential anticancer target, much less effort has been put against Hsp72. This work investigated the therapeutic potential of Hsp72 and its constitutive isoform, Hsc70, via in silico-based screening against the South African Natural Compounds Database (SANCDB). A comparative modeling approach was used to obtain nearly full-length 3D structures of the closed conformation of Hsp72 and Hsc70 proteins. Molecular docking of SANCDB compounds identified one potential allosteric modulator, Discorhabdin N, binding to the allosteric β substrate binding domain (SBDβ) back pocket, with good binding affinities in both cases.
- Full Text:
- Date Issued: 2019
- Authors: Amusengeri, Arnold , Tastan Bishop, Özlem
- Date: 2019
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/162949 , vital:40999 , https://doi.org/10.3390/molecules24010188
- Description: The human heat shock proteins (Hsps), predominantly Hsp72 and Hsp90, have been strongly implicated in various critical stages of oncogenesis and progression of human cancers. While drug development has extensively focused on Hsp90 as a potential anticancer target, much less effort has been put against Hsp72. This work investigated the therapeutic potential of Hsp72 and its constitutive isoform, Hsc70, via in silico-based screening against the South African Natural Compounds Database (SANCDB). A comparative modeling approach was used to obtain nearly full-length 3D structures of the closed conformation of Hsp72 and Hsc70 proteins. Molecular docking of SANCDB compounds identified one potential allosteric modulator, Discorhabdin N, binding to the allosteric β substrate binding domain (SBDβ) back pocket, with good binding affinities in both cases.
- Full Text:
- Date Issued: 2019