Deriving a tool to aid maintenance budget forecasting within universities of selected countries of Southern Africa
- Authors: Peters, Peter Herman
- Date: 2019
- Subjects: Budget forecasting -- Universities -- Africa, Southern
- Language: English
- Type: Thesis , Doctoral , DBA
- Identifier: http://hdl.handle.net/10948/44574 , vital:38137
- Description: In general, facilities are constructed and equipment is procured to meet the functional and utilitarian needs of an organisation. Daily use and abuse can affect the functional value of these resources and without regular maintenance there will be no real benefits derived from non-functional facilities and equipment. Conducting effective and systematic maintenance is one of the fundamentals which underpins the success of an organisation and if ignored, could be costly to rectify. Costs escalate in the form of deferred maintenance budgets, which have a knock-on effect of growing year on year. This highlights the context of universities’ operations managers who may lack proper management and planning tools to either use or apply effective maintenance budget forecasting models. Having properly maintained facilities is imperative since deferring maintenance will adversely affect employees’ occupational health and safety, impact on the cost of operations and the morale of those who use the dysfunctional facility. The most daunting task of facility managers, is to ensure that all facilities remain fully and consistently operational. This entails providing an efficient maintenance service, which prevents system failures and extends the useful life of both the production plant and facilities to be managed. The need to protect costly and varied assets against the depredation of time and keeping it maintained for current use takes significant and continuous investment of time, money and human resources. Due to the cost of maintenance, in most instances maintenance is scheduled to be done when actual facilities are not in operation, usually at the end of a financial or calendar year. The intangible nature of the maintenance function and the inability to completely justify maintenance funding budgets, lead to the required funding not being obtained from a budgetary request. This inevitably has the undesirable consequences of huge capital backlogs in the form of deferred maintenance. This study moves the research problem and argument away from strictly for-profit business (manufacturing) entities to interrogate service-oriented parastatal and hybrid funded University facilities’ operations and maintenance management. Universities are multidisciplinary structures that encompass a broad spectrum of services required to ensure the effective and efficient academic, administrative, experimental and research focused operation of the Institution. Universities are not excluded from ensuring that sufficient funding is obtained for the effective maintenance of their facilities. This research aims to derive a tool to simplify the selection of a suitable maintenance budget forecasting model and to recommend a maintenance budgeting model for use within universities of selected countries of Southern Africa. The literature survey revealed that there are numerous maintenance budgeting forecasting models already in existence in many different shapes and sizes. For this reason, a content analysis was conducted of 31 maintenance budget forecasting models in order to be able to differentiate between the numerous models. This empirical study conducted among universities of selected countries of Southern Africa outlined the current maintenance funding models being used, inclusive of the amount of funding obtained and the existence/lack of deferred maintenance of various Institutions. After analysing the secondary data (in the form of a content analysis) and the empirical data collected, a model was chosen to recommend for implementation in future institutional planning and business practice. Based on the content analysis and empirical review, the recommended maintenance budget selection tool was derived focusing on sharpening the decision making process of selecting a suitable, fit for purpose, maintenance funding model. After this phase of the research, a follow up phase was conducted amongst high level executive decision makers, to qualitatively verify or support the findings from the first phase of the data collection. This research therefore concludes with recommendations to the respondent universities of selected countries of Southern Africa, about a suitable maintenance budgeting forecasting model. It also recommends a selection tool to use if alternative maintenance budget funding models need to be selected. This multidisciplinary study contributes to the literature by contextualising the maintenance budget forecasting for operational universities and in future adding significant value to the proactive management of deferred maintenance in practice.
- Full Text:
- Date Issued: 2019
- Authors: Peters, Peter Herman
- Date: 2019
- Subjects: Budget forecasting -- Universities -- Africa, Southern
- Language: English
- Type: Thesis , Doctoral , DBA
- Identifier: http://hdl.handle.net/10948/44574 , vital:38137
- Description: In general, facilities are constructed and equipment is procured to meet the functional and utilitarian needs of an organisation. Daily use and abuse can affect the functional value of these resources and without regular maintenance there will be no real benefits derived from non-functional facilities and equipment. Conducting effective and systematic maintenance is one of the fundamentals which underpins the success of an organisation and if ignored, could be costly to rectify. Costs escalate in the form of deferred maintenance budgets, which have a knock-on effect of growing year on year. This highlights the context of universities’ operations managers who may lack proper management and planning tools to either use or apply effective maintenance budget forecasting models. Having properly maintained facilities is imperative since deferring maintenance will adversely affect employees’ occupational health and safety, impact on the cost of operations and the morale of those who use the dysfunctional facility. The most daunting task of facility managers, is to ensure that all facilities remain fully and consistently operational. This entails providing an efficient maintenance service, which prevents system failures and extends the useful life of both the production plant and facilities to be managed. The need to protect costly and varied assets against the depredation of time and keeping it maintained for current use takes significant and continuous investment of time, money and human resources. Due to the cost of maintenance, in most instances maintenance is scheduled to be done when actual facilities are not in operation, usually at the end of a financial or calendar year. The intangible nature of the maintenance function and the inability to completely justify maintenance funding budgets, lead to the required funding not being obtained from a budgetary request. This inevitably has the undesirable consequences of huge capital backlogs in the form of deferred maintenance. This study moves the research problem and argument away from strictly for-profit business (manufacturing) entities to interrogate service-oriented parastatal and hybrid funded University facilities’ operations and maintenance management. Universities are multidisciplinary structures that encompass a broad spectrum of services required to ensure the effective and efficient academic, administrative, experimental and research focused operation of the Institution. Universities are not excluded from ensuring that sufficient funding is obtained for the effective maintenance of their facilities. This research aims to derive a tool to simplify the selection of a suitable maintenance budget forecasting model and to recommend a maintenance budgeting model for use within universities of selected countries of Southern Africa. The literature survey revealed that there are numerous maintenance budgeting forecasting models already in existence in many different shapes and sizes. For this reason, a content analysis was conducted of 31 maintenance budget forecasting models in order to be able to differentiate between the numerous models. This empirical study conducted among universities of selected countries of Southern Africa outlined the current maintenance funding models being used, inclusive of the amount of funding obtained and the existence/lack of deferred maintenance of various Institutions. After analysing the secondary data (in the form of a content analysis) and the empirical data collected, a model was chosen to recommend for implementation in future institutional planning and business practice. Based on the content analysis and empirical review, the recommended maintenance budget selection tool was derived focusing on sharpening the decision making process of selecting a suitable, fit for purpose, maintenance funding model. After this phase of the research, a follow up phase was conducted amongst high level executive decision makers, to qualitatively verify or support the findings from the first phase of the data collection. This research therefore concludes with recommendations to the respondent universities of selected countries of Southern Africa, about a suitable maintenance budgeting forecasting model. It also recommends a selection tool to use if alternative maintenance budget funding models need to be selected. This multidisciplinary study contributes to the literature by contextualising the maintenance budget forecasting for operational universities and in future adding significant value to the proactive management of deferred maintenance in practice.
- Full Text:
- Date Issued: 2019
Descriptive guidelines for mediation to enhance the parental involvement of unmarried fathers
- Authors: Nordien-Lagardien, Razia
- Date: 2019
- Subjects: Mediation , Unmarried fathers -- South Africa Father and child -- South Africa Unmarried mothers -- South Africa
- Language: English
- Type: Thesis , Doctoral , DPhil
- Identifier: http://hdl.handle.net/10948/30462 , vital:30948
- Description: A significant change brought about by the Children’s Act 38 of 2005 (RSA, 2006), is that of the status of unmarried fathers. The parental rights of unmarried fathers have evolved in South Africa, especially since the Children’s Act 38 of 2005 (RSA, 2006) now recognises that unmarried fathers should have inherent right of contact, guardianship and care. These rights are, however, not automatic and need to be acquired through a process of mediation. While this legislation aims to facilitate the parental involvement of fathers by giving them rights as per Section 21 of the Children’s Act 38 of 2005 (RSA, 2006), the reality is that many unmarried fathers still remain challenged in this regard despite the change in their legal position as fathers. Unmarried fathers are often compelled to take the matter further through protracted court processes. Unmarried fathers face unique challenges with parental involvement after separation and they often need to negotiate their involvement with the mother after separation. Given that mediation between unmarried parents is in its infancy in South Africa, very little research has been done in this area. It was envisaged that this study would highlight the important aspects of mediation which need to be considered in order for mediation outcomes to be more successful and to enhance the co-parenting relationship. The study employed a qualitative research approach that was exploratory, descriptive and contextual in design. The research study consisted of three phases. Phase 1 employed a multiple case study design in order to develop an understanding of the experiences and perceptions of unmarried fathers and mothers, as well as mediators, regarding the parental responsibilities of unmarried fathers in addition to their experiences of mediation. The data collection process comprised in-depth semi-structured interviews with three sample groups, namely unmarried fathers, and mothers, and mediators. The data collected from the interviews were transcribed, coded and analysed by the researcher through the use of two techniques, namely: within-case analysis and cross-case synthesis. An independent coder was utilised to verify the coding and analysis process. The analysis of the data in Phase 1 revealed that the construction of the role of unmarried fathers is influenced by various factors such as cultural and religious influences; childhood experiences of fatherhood; societal constructions of the father’s role, and the perception of the legal rights of unmarried fathers. The new legislation pertaining to the responsibilities and rights of unmarried fathers, as contained in the Children’s Act 38 of 2005 (RSA, 2006), has resulted in increased parental conflict between parents after separation owing to their lack of awareness and confusion regarding the changes in legislation pertaining to the rights of unmarried fathers and the role of customary law in this regard. This has resulted in misconceptions about the legal rights of unmarried fathers, which have influenced unmarried parents’ attitudes and receptiveness to mediation. A significant barrier to father involvement emanating from the findings was relationship conflict experienced after separation, which was also identified as a significant challenge in mediation. The discussion of the themes reflected both positive and negative experiences of mediation for the study participants. While the parents derived educational and therapeutic benefits from mediation; there were also several factors such as relationship conflict, cultural barriers, influences of the extended family, and the approach and skills of the mediator, which influenced the mediation process. In Phase 2 of the study an integrative literature review and synthesis of the literature was conducted and critically appraised in terms of emergent themes and relevant research in the area of family mediation, which would inform the process of developing the descriptive guidelines for mediation with unmarried parents. The empirical findings from the study were synthesised with the findings from the integrative literature review, thus enabling conclusions to be drawn in order to generate descriptive guidelines for mediation. Phase 3 of the study describes the guidelines for mediation which emanated from the synthesis of the findings in Phase 1 and Phase 2 of the study. As part of a qualitative evaluation, the guidelines were presented to an expert panel for review, after which the guidelines were finalised. The proposed guidelines for mediation to enhance the parental involvement of unmarried fathers is based on the hybrid model of mediation, which incorporates elements from the Transformative approach, the African centred approach and the co-mediation model. The guidelines are further described in terms of a phased approach to mediation.
- Full Text:
- Date Issued: 2019
- Authors: Nordien-Lagardien, Razia
- Date: 2019
- Subjects: Mediation , Unmarried fathers -- South Africa Father and child -- South Africa Unmarried mothers -- South Africa
- Language: English
- Type: Thesis , Doctoral , DPhil
- Identifier: http://hdl.handle.net/10948/30462 , vital:30948
- Description: A significant change brought about by the Children’s Act 38 of 2005 (RSA, 2006), is that of the status of unmarried fathers. The parental rights of unmarried fathers have evolved in South Africa, especially since the Children’s Act 38 of 2005 (RSA, 2006) now recognises that unmarried fathers should have inherent right of contact, guardianship and care. These rights are, however, not automatic and need to be acquired through a process of mediation. While this legislation aims to facilitate the parental involvement of fathers by giving them rights as per Section 21 of the Children’s Act 38 of 2005 (RSA, 2006), the reality is that many unmarried fathers still remain challenged in this regard despite the change in their legal position as fathers. Unmarried fathers are often compelled to take the matter further through protracted court processes. Unmarried fathers face unique challenges with parental involvement after separation and they often need to negotiate their involvement with the mother after separation. Given that mediation between unmarried parents is in its infancy in South Africa, very little research has been done in this area. It was envisaged that this study would highlight the important aspects of mediation which need to be considered in order for mediation outcomes to be more successful and to enhance the co-parenting relationship. The study employed a qualitative research approach that was exploratory, descriptive and contextual in design. The research study consisted of three phases. Phase 1 employed a multiple case study design in order to develop an understanding of the experiences and perceptions of unmarried fathers and mothers, as well as mediators, regarding the parental responsibilities of unmarried fathers in addition to their experiences of mediation. The data collection process comprised in-depth semi-structured interviews with three sample groups, namely unmarried fathers, and mothers, and mediators. The data collected from the interviews were transcribed, coded and analysed by the researcher through the use of two techniques, namely: within-case analysis and cross-case synthesis. An independent coder was utilised to verify the coding and analysis process. The analysis of the data in Phase 1 revealed that the construction of the role of unmarried fathers is influenced by various factors such as cultural and religious influences; childhood experiences of fatherhood; societal constructions of the father’s role, and the perception of the legal rights of unmarried fathers. The new legislation pertaining to the responsibilities and rights of unmarried fathers, as contained in the Children’s Act 38 of 2005 (RSA, 2006), has resulted in increased parental conflict between parents after separation owing to their lack of awareness and confusion regarding the changes in legislation pertaining to the rights of unmarried fathers and the role of customary law in this regard. This has resulted in misconceptions about the legal rights of unmarried fathers, which have influenced unmarried parents’ attitudes and receptiveness to mediation. A significant barrier to father involvement emanating from the findings was relationship conflict experienced after separation, which was also identified as a significant challenge in mediation. The discussion of the themes reflected both positive and negative experiences of mediation for the study participants. While the parents derived educational and therapeutic benefits from mediation; there were also several factors such as relationship conflict, cultural barriers, influences of the extended family, and the approach and skills of the mediator, which influenced the mediation process. In Phase 2 of the study an integrative literature review and synthesis of the literature was conducted and critically appraised in terms of emergent themes and relevant research in the area of family mediation, which would inform the process of developing the descriptive guidelines for mediation with unmarried parents. The empirical findings from the study were synthesised with the findings from the integrative literature review, thus enabling conclusions to be drawn in order to generate descriptive guidelines for mediation. Phase 3 of the study describes the guidelines for mediation which emanated from the synthesis of the findings in Phase 1 and Phase 2 of the study. As part of a qualitative evaluation, the guidelines were presented to an expert panel for review, after which the guidelines were finalised. The proposed guidelines for mediation to enhance the parental involvement of unmarried fathers is based on the hybrid model of mediation, which incorporates elements from the Transformative approach, the African centred approach and the co-mediation model. The guidelines are further described in terms of a phased approach to mediation.
- Full Text:
- Date Issued: 2019
Design and fabrication of components of dye sensitised solar cells
- Authors: Msane, Gugu
- Date: 2019
- Subjects: Dye-sensitized solar cells
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/117106 , vital:34478
- Description: In recent decades there has been increasing global concern about the sustainability of our use of fossil fuels, which has led to increased interest in carbon–free sustainable renewable sources such as solar energy. Dye sensitized solar cells (DSSCs) are a cheap and clean technology that harnesses solar energy efficiently and convert it to electrical energy. A DSSC consists of a transparent working electrode coated with a dye-sensitized mesoporous film of nanocrystalline particles of semiconductor e.g. TiO2, an electrolyte containing a suitable redox couple and a platinized counter electrode. All the components of the DSSCs play vital roles in controlling the performance of the cell. The synergy of these components of the cells also needs to be investigated to optimise their interaction and create efficient and stable DSSCs. The information gathered from this investigation can give insight on how to improve the efficiencies of DSSCs. In this research study the semiconductor, transparent conducting layer and sensitizer were designed, optimized one at a time and their effect on the overall efficiency of the DSSCs studied. In this way it was easy to observe the effect of the individual components on the efficiency of the DSSCs. The conventional DSSCs usually use TiO2 as a semiconductor. In this research TiO2 was doped with cerium (Ce) to enhance its optical properties by reducing the band gap. A series of Ce-doped TiO2 with Ce content ranging from 0.1 to 1 mol % were successfully synthesized by an acid catalyzed sol-gel method, and their performance as the photoanodes of dye-sensitized solar cells (DSSCs) was investigated. Ce doping resulted in a red shift in the absorption of the TiO2 indicating narrowing of the band gap. The band gap first narrowed with increase in concentration of dopant up until 0.9 % dopant concentration. After this optimum doping concentration the band gap widened again. DFT calculations showed that Ce doping introduces Ce4f impurity states located just below the conduction band resulting in band gap narrowing. Ce content (0.9%) doped TiO2 photoanodes improved the performance of DSSCs with a conversion efficiency of 2.11% compared to 0,21% for the one with a pure TiO2 under 1 sun, AM1.5. Graphitised/TiO2 nanocomposites were also used a semiconductor to slow down recombination of electrons and holes in the cells. Electrophoretic deposition (EPD) was used to deposit graphitised/TiO2 nanocomposites onto an FTO electrode for application as photoelectrode in dye-sensitized solar cells (DSSCs). An enhanced power conversion efficiency (PCE) of 2.25% was observed for the 0.5 wt% graphene oxide/TiO2 (GO/TiO2) based DSSC which was higher than that of the conversion efficiency of pure TiO2 nanoparticles (i.e. 0.52%). Graphene oxide led to high migration of photoinduced electrons to the conduction band of the collection electrode and inhibition of charge carriers recombination resulting in enhanced photoconversion efficiency. A GO content above 0.5 % resulted in a reduced transparency leading to a decrease in the PCE. 0.5 wt % GO/0.9 Ce–TiO2 Ce based DSSC showed a slightly enhanced efficiency of 2.45%. 0.5 rGO/TiO2 based DSSCs had a high efficiency than 0.5 rGO/TiO2 due to improved conductivity of rGO nanosheets and suppressed recombination of charge carriers. To cut down DSSC production costs a silver wire network transparent conducting polyethylene electrodes was fabricated and used as an indium tin oxide (ITO) alternative substrates in DSSCs. The transmittance of the AgNW network was 82 % which is comparable to ITO substrates. Titanium oxide (TiO2) films on the AgWN/PET substrates were obtained using the electrophoresis method. These substrates were sensitised and used to fabricate a dye sensitised solar cell. From the measured current–voltage or I-V characteristic under AM1.5 illumination of the formed DSSC using AgWN substrates, an open circuit voltage (VOC) of 0.377 V, a short circuit current (ISC) of 0.0067 mA and a fill factor (FF) 25.7 % with an efficiency of 0.00862 % were obtained from a cell of 0.075 cm2 working area. The stability of the cell improved when a room temperature ionic liquid electrolyte was used. Gold nanofiber transparent electrodes were also prepared by the electrospinning techniques and used as an alternative to indium tin oxides substrates. Transparent conducting gold nanofiber (AuNF) transparent conducting electrodes were fabricated by using a low–cost electrospinning process and used as photoelectrodes for DSSCs. TiO2 was deposited on these electrodes by using an electrospray method. DSSC using AuNF as transparent electrodes had a power efficiency of 0.52%, compared to devices made with FTO electrodes (1.48%). DSSCs. Versatile dyes with increased spectral response, stability and suppressed recombination of holes and electrons were synthesised and used as a sensitizers for DSSCs. The boron dipyrrin (BODIPY) chromophore was combined with a carboxy coumarin moiety to create donor–acceptor (dyad) system dyes. Regenerative dyad dyes were formed through covalently linking a porphyrin chromophore to a manganese(II) ion through bridging ligands. These chromophores and also porphyrin and BODIPY dyes were used as sensitisers for DSSCs. The regenerative dye based DSSCs showed a photoconversion efficiency of 4.09% which was higher than the efficiency of the parent porphyrin (2.57%). The enhanced efficiency was attributed to the manganese bypridine cluster in the ZnTPP–Mn bpy supramolecule which acted as an electron donor to the photo-oxidized porphyrin continuously regenerating the porphyrin and preventing its decay.
- Full Text:
- Date Issued: 2019
- Authors: Msane, Gugu
- Date: 2019
- Subjects: Dye-sensitized solar cells
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/117106 , vital:34478
- Description: In recent decades there has been increasing global concern about the sustainability of our use of fossil fuels, which has led to increased interest in carbon–free sustainable renewable sources such as solar energy. Dye sensitized solar cells (DSSCs) are a cheap and clean technology that harnesses solar energy efficiently and convert it to electrical energy. A DSSC consists of a transparent working electrode coated with a dye-sensitized mesoporous film of nanocrystalline particles of semiconductor e.g. TiO2, an electrolyte containing a suitable redox couple and a platinized counter electrode. All the components of the DSSCs play vital roles in controlling the performance of the cell. The synergy of these components of the cells also needs to be investigated to optimise their interaction and create efficient and stable DSSCs. The information gathered from this investigation can give insight on how to improve the efficiencies of DSSCs. In this research study the semiconductor, transparent conducting layer and sensitizer were designed, optimized one at a time and their effect on the overall efficiency of the DSSCs studied. In this way it was easy to observe the effect of the individual components on the efficiency of the DSSCs. The conventional DSSCs usually use TiO2 as a semiconductor. In this research TiO2 was doped with cerium (Ce) to enhance its optical properties by reducing the band gap. A series of Ce-doped TiO2 with Ce content ranging from 0.1 to 1 mol % were successfully synthesized by an acid catalyzed sol-gel method, and their performance as the photoanodes of dye-sensitized solar cells (DSSCs) was investigated. Ce doping resulted in a red shift in the absorption of the TiO2 indicating narrowing of the band gap. The band gap first narrowed with increase in concentration of dopant up until 0.9 % dopant concentration. After this optimum doping concentration the band gap widened again. DFT calculations showed that Ce doping introduces Ce4f impurity states located just below the conduction band resulting in band gap narrowing. Ce content (0.9%) doped TiO2 photoanodes improved the performance of DSSCs with a conversion efficiency of 2.11% compared to 0,21% for the one with a pure TiO2 under 1 sun, AM1.5. Graphitised/TiO2 nanocomposites were also used a semiconductor to slow down recombination of electrons and holes in the cells. Electrophoretic deposition (EPD) was used to deposit graphitised/TiO2 nanocomposites onto an FTO electrode for application as photoelectrode in dye-sensitized solar cells (DSSCs). An enhanced power conversion efficiency (PCE) of 2.25% was observed for the 0.5 wt% graphene oxide/TiO2 (GO/TiO2) based DSSC which was higher than that of the conversion efficiency of pure TiO2 nanoparticles (i.e. 0.52%). Graphene oxide led to high migration of photoinduced electrons to the conduction band of the collection electrode and inhibition of charge carriers recombination resulting in enhanced photoconversion efficiency. A GO content above 0.5 % resulted in a reduced transparency leading to a decrease in the PCE. 0.5 wt % GO/0.9 Ce–TiO2 Ce based DSSC showed a slightly enhanced efficiency of 2.45%. 0.5 rGO/TiO2 based DSSCs had a high efficiency than 0.5 rGO/TiO2 due to improved conductivity of rGO nanosheets and suppressed recombination of charge carriers. To cut down DSSC production costs a silver wire network transparent conducting polyethylene electrodes was fabricated and used as an indium tin oxide (ITO) alternative substrates in DSSCs. The transmittance of the AgNW network was 82 % which is comparable to ITO substrates. Titanium oxide (TiO2) films on the AgWN/PET substrates were obtained using the electrophoresis method. These substrates were sensitised and used to fabricate a dye sensitised solar cell. From the measured current–voltage or I-V characteristic under AM1.5 illumination of the formed DSSC using AgWN substrates, an open circuit voltage (VOC) of 0.377 V, a short circuit current (ISC) of 0.0067 mA and a fill factor (FF) 25.7 % with an efficiency of 0.00862 % were obtained from a cell of 0.075 cm2 working area. The stability of the cell improved when a room temperature ionic liquid electrolyte was used. Gold nanofiber transparent electrodes were also prepared by the electrospinning techniques and used as an alternative to indium tin oxides substrates. Transparent conducting gold nanofiber (AuNF) transparent conducting electrodes were fabricated by using a low–cost electrospinning process and used as photoelectrodes for DSSCs. TiO2 was deposited on these electrodes by using an electrospray method. DSSC using AuNF as transparent electrodes had a power efficiency of 0.52%, compared to devices made with FTO electrodes (1.48%). DSSCs. Versatile dyes with increased spectral response, stability and suppressed recombination of holes and electrons were synthesised and used as a sensitizers for DSSCs. The boron dipyrrin (BODIPY) chromophore was combined with a carboxy coumarin moiety to create donor–acceptor (dyad) system dyes. Regenerative dyad dyes were formed through covalently linking a porphyrin chromophore to a manganese(II) ion through bridging ligands. These chromophores and also porphyrin and BODIPY dyes were used as sensitisers for DSSCs. The regenerative dye based DSSCs showed a photoconversion efficiency of 4.09% which was higher than the efficiency of the parent porphyrin (2.57%). The enhanced efficiency was attributed to the manganese bypridine cluster in the ZnTPP–Mn bpy supramolecule which acted as an electron donor to the photo-oxidized porphyrin continuously regenerating the porphyrin and preventing its decay.
- Full Text:
- Date Issued: 2019
Design of metal ion-selective reagents for recovery of precious metals
- Authors: Moleko-Boyce, Pulleng
- Date: 2019
- Subjects: Bioinorganic chemistry , Metal complexes Speciation (Chemistry)
- Language: English
- Type: Thesis , Doctoral , DPhil
- Identifier: http://hdl.handle.net/10948/42510 , vital:36664
- Description: The study is divided into two sections; namely, (1) the design of rhodium(III) specific chelating ligands (tridentate bis-benzimidazole derivatives), and (2) the development of iridium(IV)-specific quaternary diammonium cations with electron donating and electron withdrawing groups. Bis-benzimidazole chelating ligands used were bis((1H-benzimidazol-2-yl)methyl)amine (NNN1), bis((1H-benzimidazol-2-yl)ethyl)amine (NNN2), bis((1H-benzimidazol-2-yl)methyl)sulfide (NSN1) and bis((1H-benzimidazol-2-yl)ethyl)sulfide (NSN2). Quaternary diammonium cations used were tetramethylbenzyl-1,10-diammonium chloride (QuatDMDAMeBnz), tetrabenzyl-1,10-diammonium chloride (QuatDMDABnz), tetratrifluoromethylbenzyl-1,10-diammonium chloride (QuatDMDACF3Bnz) and tetranitrobenzyl-1,10-diammonium chloride (QuatDMDANO2Bnz). For both studies, polyvinylbenzylchloride (PVBC) nanofibers were used as support material. The PVBC nanofibers which were functionalised with bis-benzimidazole derivatives and quaternary diammonium cations, respectively, were investigated for the selectivity for Rh(III) over Ir(III), Pt(II), Pd(II) and Ni(II), and for separation of Ir(IV) from Rh(III), respectively. The sorbent materials were characterised by FTIR, SEM, BET surface area, TGA, EDS and elemental analysis, and the results showed that the functionalization of the sorbent materials was successful.The efficiency of bis-benzimidazole derivatives and quaternary diammonium cations, respectively, were investigated in a column study under dynamic flow adsorption conditions. The adsorption kinetics and isotherms were investigated under batch conditions and fitted on pseudo-first-order and pseudo-second-order model, and Freundlich and Langmuir isotherm, respectively. It was observed that the bis-benzimidazole derivatives showed uptake of [RhCl3(H2O)3], and the loading capacities were observed in the following order; NSN1 (181.06 mg/g) > NSN2 (148.55 mg/g) > NNN1 (131.88 mg/g) > NNN2 (75.87 mg/g). The bis-benzimidazole derivatives preference for metal ions was further investigated with a multi-element solution containing Rh(III), Ir(III), Pt(II), Pd(II) and Ni(II). The bis-benzimidazole derivatives showed the following order of loading capacity: NSN1 (47.28 mg/g) > NSN2 (23.89 mg/g) > NNN1 (17.47 mg/g) > NNN2 (14.91 mg/g) for Rh(III); NSN2 (10.64 mg/g) > NNN2 (6.84 mg/g) > NSN1 (5.74 mg/g) > NNN1 (5.02 mg/g) for Ir(III); NNN2 (33.96 mg/g) > NSN1 (30.95 mg/g) > NSN2 (19.95 mg/g) > NNN1 (14.92 mg/g) for Pt(II); NNN1 (47.94 mg/g) > NNN2 (28.90 mg/g) > NSN1 (16.22 mg/g) > NSN2 (15.83 mg/g) for Pd(II). Bis-benzimidazole derivatives showed no uptake of nickel(II) under these conditions. It was observed the ligand-selectivity order for Rh(III) was similar in both single-element and multi-element studies. This order showed that the bis-benzimidazoles containing a sulfur atom showed a high preference for rhodium(III) compared to Pt(II) which had a high preference for NNN2 as well as Pd(II) which had a high preference for NNN1. Ir(III) generally had a lower preference for the ligands presumably due to its higher kinetic inertness compared with Rh(III). Column sorption of [IrCl6]2- and [RhCl5(H2O)]2- on nanofibers functionalized with diammonium cations was carried out and the loading capacities of [IrCl6]2- were obtained. [RhCl5(H2O)]2- was not adsorbed by the sorbent materials while [IrCl6]2- was loaded onto the column. The loading capacities of [IrCl6]2- with the quaternary diammonium sorbent materials increased in the order of F-QuatDMDAMeBnz (60.29 mg/g) < F-QuatDMDABnz (67.61 mg/g) < F-QuatDMDACF3Bnz (107.59 mg/g) < F-QuatDMDANO2Bnz (140.47 mg/g). The loading capacity for Ir(IV) with quaternary diammonium cationic nanofibers increased with an increase in the electron-withdrawing nature of the quaternizing group. The charge delocalizing ability of the nitrobenzyl group resulted in the best interaction of the diammonium cation with [IrCl6]2-. Batch equilibrium studies were carried out to assess the efficiency of bis-benzimidazole chelating derivatives as adsorbents using a multi-metal solution (Rh(III), Ir(III), Pt(II), Pd(II) and Ni(II)) in 0.5 M HCl. The efficiency of the quaternary diammonium cations was tested using a binary metal solution (Ir(IV) and Rh(III)) in 6 M HCl. The isothermal batch adsorption studies of a multi-metal solution with bis-benzimidazoles derivatives fitted the Langmuir isotherm model which confirmed monolayer adsorption onto a homogeneous surface. The Langmuir isotherm parameter (qe (mg/g)), using functionalized nanofibers, showed the order of NNN2 (128.21 mg/g) > NSN1 (99.01 mg/g) > NSN2 (91.74 mg/g) > NNN1 (84.03 mg/g) for Pt(II); NNN1 (66.23 mg/g) > NNN2 (5.89 mg/g) > NSN1 (1.40 mg/g) > NSN2 (0.59 mg/g) for Pd(II); NSN2 (10.64 mg/g) > NNN2 (6.84 mg/g) > NSN1 (5.74 mg/g) > NNN1 (5.02 mg/g) for Ir(III); NSN1 (140.85 mg/g) > NSN2 (109.89 mg/g) > NNN1 (104.17 mg/g) > NNN2 (91.74 mg/g) for Rh(III). The pseudo-first-order kinetics model was found to be the best fit to describe the adsorption kinetics of all metal ions onto all the sorbent materials. K1 (min-1) value in pseudo-first-order kinetics showed the same order of adsorption as observed in the Langmuir isotherms. The isothermal batch adsorption studies of [IrCl6]2- and [RhCl5(H2O)]2- with quaternary diammonium cations fitted the Freundlich isotherm model and confirmed to be effective for multiple-layered adsorption onto a heterogeneous surface. The Freundlich isotherm parameter (kf (mg/g)) using functionalized quaternary diammonium cationic nanofibers increased in the order of F-QuatDMDANO2Bnz (794.33 mg/g) > F-QuatDMDACF3Bnz (185.35 mg/g) > F-QuatDMDABnz (156.32 mg/g) > F-QuatDMDAMeBnz (112.46 mg/g) for Ir(IV) uptake. F-QuatDMDANO2Bnz resin showed the highest adsorption than that of F-QuatDMDAMeBnz, F-QuatDMDABnz and F-QuatDMDACF3Bnz and this order is similar to what was observed in column studies. The quaternary diammonium cations were shown to have the highest adsorption capacity for Ir(IV) compared with Rh(III). The adsorption of Rh(III) was also observed to increase in the order of F-QuatDMDANO2Bnz (177.83 mg/g) > F-QuatDMDACF3Bnz (40.37 mg/g) > F-QuatDMDABnz (36.98 mg/g) > F-QuatDMDAMeBnz (12.71 mg/g). The pseudo-second-order kinetic model was found to be the best fit to describe the adsorption kinetics of both metal ions onto all the sorbent materials. K2 (g.mg-1min-1) value in pseudo-second-order kinetics showed the same order of adsorption as observed in the Freundlich isotherms. The adsorption studies showed adsorption takes place via chemisorption process. This thesis presents PGMs and iridium-specific materials that could be applied in solutions of secondary PGMs sources containing rhodium, platinum and palladium with bis-benzimidazoles as well as in feed solutions from ore processing with diammonium cations for iridium recovery.
- Full Text:
- Date Issued: 2019
- Authors: Moleko-Boyce, Pulleng
- Date: 2019
- Subjects: Bioinorganic chemistry , Metal complexes Speciation (Chemistry)
- Language: English
- Type: Thesis , Doctoral , DPhil
- Identifier: http://hdl.handle.net/10948/42510 , vital:36664
- Description: The study is divided into two sections; namely, (1) the design of rhodium(III) specific chelating ligands (tridentate bis-benzimidazole derivatives), and (2) the development of iridium(IV)-specific quaternary diammonium cations with electron donating and electron withdrawing groups. Bis-benzimidazole chelating ligands used were bis((1H-benzimidazol-2-yl)methyl)amine (NNN1), bis((1H-benzimidazol-2-yl)ethyl)amine (NNN2), bis((1H-benzimidazol-2-yl)methyl)sulfide (NSN1) and bis((1H-benzimidazol-2-yl)ethyl)sulfide (NSN2). Quaternary diammonium cations used were tetramethylbenzyl-1,10-diammonium chloride (QuatDMDAMeBnz), tetrabenzyl-1,10-diammonium chloride (QuatDMDABnz), tetratrifluoromethylbenzyl-1,10-diammonium chloride (QuatDMDACF3Bnz) and tetranitrobenzyl-1,10-diammonium chloride (QuatDMDANO2Bnz). For both studies, polyvinylbenzylchloride (PVBC) nanofibers were used as support material. The PVBC nanofibers which were functionalised with bis-benzimidazole derivatives and quaternary diammonium cations, respectively, were investigated for the selectivity for Rh(III) over Ir(III), Pt(II), Pd(II) and Ni(II), and for separation of Ir(IV) from Rh(III), respectively. The sorbent materials were characterised by FTIR, SEM, BET surface area, TGA, EDS and elemental analysis, and the results showed that the functionalization of the sorbent materials was successful.The efficiency of bis-benzimidazole derivatives and quaternary diammonium cations, respectively, were investigated in a column study under dynamic flow adsorption conditions. The adsorption kinetics and isotherms were investigated under batch conditions and fitted on pseudo-first-order and pseudo-second-order model, and Freundlich and Langmuir isotherm, respectively. It was observed that the bis-benzimidazole derivatives showed uptake of [RhCl3(H2O)3], and the loading capacities were observed in the following order; NSN1 (181.06 mg/g) > NSN2 (148.55 mg/g) > NNN1 (131.88 mg/g) > NNN2 (75.87 mg/g). The bis-benzimidazole derivatives preference for metal ions was further investigated with a multi-element solution containing Rh(III), Ir(III), Pt(II), Pd(II) and Ni(II). The bis-benzimidazole derivatives showed the following order of loading capacity: NSN1 (47.28 mg/g) > NSN2 (23.89 mg/g) > NNN1 (17.47 mg/g) > NNN2 (14.91 mg/g) for Rh(III); NSN2 (10.64 mg/g) > NNN2 (6.84 mg/g) > NSN1 (5.74 mg/g) > NNN1 (5.02 mg/g) for Ir(III); NNN2 (33.96 mg/g) > NSN1 (30.95 mg/g) > NSN2 (19.95 mg/g) > NNN1 (14.92 mg/g) for Pt(II); NNN1 (47.94 mg/g) > NNN2 (28.90 mg/g) > NSN1 (16.22 mg/g) > NSN2 (15.83 mg/g) for Pd(II). Bis-benzimidazole derivatives showed no uptake of nickel(II) under these conditions. It was observed the ligand-selectivity order for Rh(III) was similar in both single-element and multi-element studies. This order showed that the bis-benzimidazoles containing a sulfur atom showed a high preference for rhodium(III) compared to Pt(II) which had a high preference for NNN2 as well as Pd(II) which had a high preference for NNN1. Ir(III) generally had a lower preference for the ligands presumably due to its higher kinetic inertness compared with Rh(III). Column sorption of [IrCl6]2- and [RhCl5(H2O)]2- on nanofibers functionalized with diammonium cations was carried out and the loading capacities of [IrCl6]2- were obtained. [RhCl5(H2O)]2- was not adsorbed by the sorbent materials while [IrCl6]2- was loaded onto the column. The loading capacities of [IrCl6]2- with the quaternary diammonium sorbent materials increased in the order of F-QuatDMDAMeBnz (60.29 mg/g) < F-QuatDMDABnz (67.61 mg/g) < F-QuatDMDACF3Bnz (107.59 mg/g) < F-QuatDMDANO2Bnz (140.47 mg/g). The loading capacity for Ir(IV) with quaternary diammonium cationic nanofibers increased with an increase in the electron-withdrawing nature of the quaternizing group. The charge delocalizing ability of the nitrobenzyl group resulted in the best interaction of the diammonium cation with [IrCl6]2-. Batch equilibrium studies were carried out to assess the efficiency of bis-benzimidazole chelating derivatives as adsorbents using a multi-metal solution (Rh(III), Ir(III), Pt(II), Pd(II) and Ni(II)) in 0.5 M HCl. The efficiency of the quaternary diammonium cations was tested using a binary metal solution (Ir(IV) and Rh(III)) in 6 M HCl. The isothermal batch adsorption studies of a multi-metal solution with bis-benzimidazoles derivatives fitted the Langmuir isotherm model which confirmed monolayer adsorption onto a homogeneous surface. The Langmuir isotherm parameter (qe (mg/g)), using functionalized nanofibers, showed the order of NNN2 (128.21 mg/g) > NSN1 (99.01 mg/g) > NSN2 (91.74 mg/g) > NNN1 (84.03 mg/g) for Pt(II); NNN1 (66.23 mg/g) > NNN2 (5.89 mg/g) > NSN1 (1.40 mg/g) > NSN2 (0.59 mg/g) for Pd(II); NSN2 (10.64 mg/g) > NNN2 (6.84 mg/g) > NSN1 (5.74 mg/g) > NNN1 (5.02 mg/g) for Ir(III); NSN1 (140.85 mg/g) > NSN2 (109.89 mg/g) > NNN1 (104.17 mg/g) > NNN2 (91.74 mg/g) for Rh(III). The pseudo-first-order kinetics model was found to be the best fit to describe the adsorption kinetics of all metal ions onto all the sorbent materials. K1 (min-1) value in pseudo-first-order kinetics showed the same order of adsorption as observed in the Langmuir isotherms. The isothermal batch adsorption studies of [IrCl6]2- and [RhCl5(H2O)]2- with quaternary diammonium cations fitted the Freundlich isotherm model and confirmed to be effective for multiple-layered adsorption onto a heterogeneous surface. The Freundlich isotherm parameter (kf (mg/g)) using functionalized quaternary diammonium cationic nanofibers increased in the order of F-QuatDMDANO2Bnz (794.33 mg/g) > F-QuatDMDACF3Bnz (185.35 mg/g) > F-QuatDMDABnz (156.32 mg/g) > F-QuatDMDAMeBnz (112.46 mg/g) for Ir(IV) uptake. F-QuatDMDANO2Bnz resin showed the highest adsorption than that of F-QuatDMDAMeBnz, F-QuatDMDABnz and F-QuatDMDACF3Bnz and this order is similar to what was observed in column studies. The quaternary diammonium cations were shown to have the highest adsorption capacity for Ir(IV) compared with Rh(III). The adsorption of Rh(III) was also observed to increase in the order of F-QuatDMDANO2Bnz (177.83 mg/g) > F-QuatDMDACF3Bnz (40.37 mg/g) > F-QuatDMDABnz (36.98 mg/g) > F-QuatDMDAMeBnz (12.71 mg/g). The pseudo-second-order kinetic model was found to be the best fit to describe the adsorption kinetics of both metal ions onto all the sorbent materials. K2 (g.mg-1min-1) value in pseudo-second-order kinetics showed the same order of adsorption as observed in the Freundlich isotherms. The adsorption studies showed adsorption takes place via chemisorption process. This thesis presents PGMs and iridium-specific materials that could be applied in solutions of secondary PGMs sources containing rhodium, platinum and palladium with bis-benzimidazoles as well as in feed solutions from ore processing with diammonium cations for iridium recovery.
- 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
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
Diversity, host plant range and ecology of Lepidoptera stem borers in South Africa
- Authors: Stemele, Mxolisi Arnold
- Date: 2019
- Subjects: Lepidoptera Host plants Stem borers
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10353/15409 , vital:40405
- Description: The biology and ecology of Lepidopteran pests stem borers has been extensively studied because of the economic importance of pest species such as Busseola fusca (Fuller) (Noctuidae), Sesamia calamistis (Hampson) (Noctuidae), Chilo partellus (Swinhoe) (Crambidae), and Eldana saccharina (Walker) (Pyralidae). Knowledge relating to diversity, infestation dynamics, and host plant range is readily available. In natural vegetation, the variety of stem borers is higher than that found in agroecosystems. However, there is a paucity of South African studies that explain the observed differences in diversity between the two systems. Stem borers are also known to exhibit species-specific ecological requirements, which influence their distribution between African countries. South African biomes are classified based on vegetation structure and climate, which happens to be the most critical factors that affect the distribution of phytophagous insects. This makes biomes an excellent model to investigate diversity and distribution of stem borer species. In this study, we investigated diversity, distribution and species composition in four biomes. The results showed that diversity and distribution of the stem borers in natural vegetation was determined by host plant distribution. Stem borer diversity correlated with high diversity of host plants. Thirty-two stem borer species were collected from 27 host plants and another three from light traps. Widely distributed host plants supported a higher diversity of stem borers, which is consistent with the resource availability hypotheses. Non-metric dimensional scale unfolding revealed disparity in host plant preference and plant species composition between the various stem borer families (Kruskal’s Stress = 0.16). Tortricidae species and Sesamia typhae (Le rü) (Noctuidae) feed exclusively on hydrophytic Cyperaceae species. The majority of Noctuidae, Crambidae and Phycitidae species collected were oligophagous on terrestrial Poaceae, with a few polyphagous exceptions feeding on hydrophytic Cyperaceae and Typhaceae. Additionally, species composition of Poaceae host plants differed between 8 Crambidae and the Phycitidae species. Stem borer species composition between biomes revealed the presence of distinct host plants (2D stress = 0.09) and stem borer (2D stress = 0.13) communities. The stem borer abundance and diversity were strongly correlated (R2 = 0.64), but species diversity (R2 = - 0.95) and host plant diversity (R2 = - 0.85) were inversely correlated to altitude. Based on these results it was concluded that stem borer diversity and distribution in natural vegetation was influenced by host plant diversity and distribution as well as climate associated with altitudinal gradients. In the last two decades, four stem borer species previously known on wild host plants; Busseola segeta (Bowden), Busseola phaia (Bowden), Pirateolea piscator (Fletcher) and Conicofrontia sesamoides (Hampson) have invaded cultivated crops. These invasions remained undetected because of a shortage of surveys, habitat transformation and misidentifications. Misidentifications are common among stem borers due to the considerable resemblance between morphospecies. In this study, we assessed the capacity of the mitochondrial gene Cytochrome c oxidase (COI) to delineate closely related species to develop monitoring and early detection of invasive species and to assess migration patterns and gene flow between the populations. The results demonstrated that COI is an effective DNA marker for species delineation and assessment of intra- and interspecific genetic relationship. The K2P distances and phylogenetic tree defined boundaries between Noctuidae species with high resolution. No divergence distance was detected between intraspecific species, but for the congener species, divergence distance was 0.044%-0.111% with an average of 0.076%. The average interspecies K2P distance (0.57%) was 5-15 times higher than the congener species distances. Phylogenetic analysis revealed the presence of two clades. Busseola and Sesamia species were connected in a monophyletic clade with a strong (93%) bootstrap. The second monophyletic clade comprised of a cluster of Pirateolea, Acrapex and Conicofrontia species, and this was also supported with 9 a strong bootstrap (100%). The gene flow study revealed low levels of genetic differentiation between the populations of B. fusca collected from different maize producing areas in South Africa. This low genetic differentiation was consistent with high gene flow. The number of effective migrants between the populations was between 8 and 99 individuals per generation. These results indicate high connectivity between the populations.
- Full Text:
- Date Issued: 2019
- Authors: Stemele, Mxolisi Arnold
- Date: 2019
- Subjects: Lepidoptera Host plants Stem borers
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10353/15409 , vital:40405
- Description: The biology and ecology of Lepidopteran pests stem borers has been extensively studied because of the economic importance of pest species such as Busseola fusca (Fuller) (Noctuidae), Sesamia calamistis (Hampson) (Noctuidae), Chilo partellus (Swinhoe) (Crambidae), and Eldana saccharina (Walker) (Pyralidae). Knowledge relating to diversity, infestation dynamics, and host plant range is readily available. In natural vegetation, the variety of stem borers is higher than that found in agroecosystems. However, there is a paucity of South African studies that explain the observed differences in diversity between the two systems. Stem borers are also known to exhibit species-specific ecological requirements, which influence their distribution between African countries. South African biomes are classified based on vegetation structure and climate, which happens to be the most critical factors that affect the distribution of phytophagous insects. This makes biomes an excellent model to investigate diversity and distribution of stem borer species. In this study, we investigated diversity, distribution and species composition in four biomes. The results showed that diversity and distribution of the stem borers in natural vegetation was determined by host plant distribution. Stem borer diversity correlated with high diversity of host plants. Thirty-two stem borer species were collected from 27 host plants and another three from light traps. Widely distributed host plants supported a higher diversity of stem borers, which is consistent with the resource availability hypotheses. Non-metric dimensional scale unfolding revealed disparity in host plant preference and plant species composition between the various stem borer families (Kruskal’s Stress = 0.16). Tortricidae species and Sesamia typhae (Le rü) (Noctuidae) feed exclusively on hydrophytic Cyperaceae species. The majority of Noctuidae, Crambidae and Phycitidae species collected were oligophagous on terrestrial Poaceae, with a few polyphagous exceptions feeding on hydrophytic Cyperaceae and Typhaceae. Additionally, species composition of Poaceae host plants differed between 8 Crambidae and the Phycitidae species. Stem borer species composition between biomes revealed the presence of distinct host plants (2D stress = 0.09) and stem borer (2D stress = 0.13) communities. The stem borer abundance and diversity were strongly correlated (R2 = 0.64), but species diversity (R2 = - 0.95) and host plant diversity (R2 = - 0.85) were inversely correlated to altitude. Based on these results it was concluded that stem borer diversity and distribution in natural vegetation was influenced by host plant diversity and distribution as well as climate associated with altitudinal gradients. In the last two decades, four stem borer species previously known on wild host plants; Busseola segeta (Bowden), Busseola phaia (Bowden), Pirateolea piscator (Fletcher) and Conicofrontia sesamoides (Hampson) have invaded cultivated crops. These invasions remained undetected because of a shortage of surveys, habitat transformation and misidentifications. Misidentifications are common among stem borers due to the considerable resemblance between morphospecies. In this study, we assessed the capacity of the mitochondrial gene Cytochrome c oxidase (COI) to delineate closely related species to develop monitoring and early detection of invasive species and to assess migration patterns and gene flow between the populations. The results demonstrated that COI is an effective DNA marker for species delineation and assessment of intra- and interspecific genetic relationship. The K2P distances and phylogenetic tree defined boundaries between Noctuidae species with high resolution. No divergence distance was detected between intraspecific species, but for the congener species, divergence distance was 0.044%-0.111% with an average of 0.076%. The average interspecies K2P distance (0.57%) was 5-15 times higher than the congener species distances. Phylogenetic analysis revealed the presence of two clades. Busseola and Sesamia species were connected in a monophyletic clade with a strong (93%) bootstrap. The second monophyletic clade comprised of a cluster of Pirateolea, Acrapex and Conicofrontia species, and this was also supported with 9 a strong bootstrap (100%). The gene flow study revealed low levels of genetic differentiation between the populations of B. fusca collected from different maize producing areas in South Africa. This low genetic differentiation was consistent with high gene flow. The number of effective migrants between the populations was between 8 and 99 individuals per generation. These results indicate high connectivity between the populations.
- Full Text:
- Date Issued: 2019
Early Jurassic dolerites of the Karoo Large Igneous Province ( KLIP): an analysis of their age and emplacement history from sea level to the Drakensberg Mountains in the Eastern Cape , South Africa Submitted
- Authors: Muedi, Thomas Tshifhiwa
- Date: 2019
- Subjects: Geological time , Geochemistry Geology -- South Africa
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10948/41908 , vital:36608
- Description: South Africa hosts one of the largest Large Igneous Provinces (LIPs that is likely linked to the early separation of East and West Gondwana. However, despite many studies, the relationship between dolerites and volcanic basalts of this LIP (also known as the Karoo Large Igneous Province or KLIP) remains unsolved, because of poorly linked age dates (timing), geochemistry and emplacement mechanisms. This problem is in part because different unreliable dating techniques with large margin of errors have been applied This study aims to address these issues by performing new geo chemical and high resolution geochronological analyses on a number of dolerites (sills and dykes), volcanic s also referred to in the literature as the Drakensberg flood basalts) and samples from drill cores and field outcrops. This project is focused on dolerites in the Eastern Cape Province and provides results from field mapping of dolerites (sills and dykes) from the sea level to an elevation of circa 1350 metres above sea level (MASL) and their link to the volcanic in the Eastern Cape Province. The dolerite dykes observed trends from metres to hundreds of kilometres and cut across volcanic, which have similar geochemistry. The intrusive dolerites collected from the field and from d rill core samples were likely emplaced by magma infiltration through pre-existing sub vertical brittle fractures and fissures and then emplaced horizontally as sills circa 183 Ma Detailed fracture mapping across host rock to the dolerite was carried out to test if they acted as possible pathways for magmatic emplacements. The dolerite dykes and fractures mapped in the host sedimentary rocks have a dominant NW direction, especially towards volcanic basalts. The project provides tests based on the geochemical relationships of the dolerites and basalts from sixty-six (66) cores and field outcrop samples. The results confirm that the chemical analyses from the volcanic basalts an d dolerites are closely related and reveal that most samples are Ocean Island Basalt OIB), but some also reveal subduction related processes. This is consistent with models that suggest subduction along south west Gondwana may have influenced plumemagmatism derived from the lower mantle that initiated break up of this supercontinent e.g de Wit and Stern 1981 Storey et al , 1992 ; Torsvik et al., 2006 and Burke et al., 2008)
- Full Text:
- Date Issued: 2019
- Authors: Muedi, Thomas Tshifhiwa
- Date: 2019
- Subjects: Geological time , Geochemistry Geology -- South Africa
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10948/41908 , vital:36608
- Description: South Africa hosts one of the largest Large Igneous Provinces (LIPs that is likely linked to the early separation of East and West Gondwana. However, despite many studies, the relationship between dolerites and volcanic basalts of this LIP (also known as the Karoo Large Igneous Province or KLIP) remains unsolved, because of poorly linked age dates (timing), geochemistry and emplacement mechanisms. This problem is in part because different unreliable dating techniques with large margin of errors have been applied This study aims to address these issues by performing new geo chemical and high resolution geochronological analyses on a number of dolerites (sills and dykes), volcanic s also referred to in the literature as the Drakensberg flood basalts) and samples from drill cores and field outcrops. This project is focused on dolerites in the Eastern Cape Province and provides results from field mapping of dolerites (sills and dykes) from the sea level to an elevation of circa 1350 metres above sea level (MASL) and their link to the volcanic in the Eastern Cape Province. The dolerite dykes observed trends from metres to hundreds of kilometres and cut across volcanic, which have similar geochemistry. The intrusive dolerites collected from the field and from d rill core samples were likely emplaced by magma infiltration through pre-existing sub vertical brittle fractures and fissures and then emplaced horizontally as sills circa 183 Ma Detailed fracture mapping across host rock to the dolerite was carried out to test if they acted as possible pathways for magmatic emplacements. The dolerite dykes and fractures mapped in the host sedimentary rocks have a dominant NW direction, especially towards volcanic basalts. The project provides tests based on the geochemical relationships of the dolerites and basalts from sixty-six (66) cores and field outcrop samples. The results confirm that the chemical analyses from the volcanic basalts an d dolerites are closely related and reveal that most samples are Ocean Island Basalt OIB), but some also reveal subduction related processes. This is consistent with models that suggest subduction along south west Gondwana may have influenced plumemagmatism derived from the lower mantle that initiated break up of this supercontinent e.g de Wit and Stern 1981 Storey et al , 1992 ; Torsvik et al., 2006 and Burke et al., 2008)
- Full Text:
- Date Issued: 2019
Ecological assessment and biogeography of coastal vegetation and flora in southern Mozambique
- Authors: Massingue, Alice Obed
- Date: 2019
- Subjects: Coastal plants -- Mozambique , Coastal plants Marine biodiversity -- Mozambique Coastal biodiversity -- Mozambique
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10948/40988 , vital:36280
- Description: This study considered aspects of the vegetation of the coastal zone of southern Mozambique, an area with a rich biodiversity. The vegetation and flora were assessed in their current state including the associated anthropogenic pressures. The environmental conditions that determined the distribution of the vegetation were evaluated. A hierarchical classification, description and ecological interpretation of the vegetation and flora of the coastal zone in southern Mozambique are presented. Analysis was based on 242 sample quadrats that were distributed in a stratified manner throughout the study area. The vegetation could be grouped into six distinct types of vegetation: Dune Forest, Coastal Forest, Coastal Grassland, Coastal Miombo, Coastal Savanna and Coastal Woodland. Species diversity was high for the all the vegetation types, particularly in the woody elements. A total of 673 species in 410 genera was recorded. They represented 104 families with Fabaceae and Rubiaceae being the most common. Of these, 6.6% were endemic or near-endemic to the coastal zone of southern Mozambique with Coastal Forest being the habitat with the greatest endemism. All soils from different vegetation types had poor agricultural potential. Soil properties were the strongest defining environmental feature separating the vegetation types: e.g. pH was high in Dune Forest compared to the others. Results from Maxent modelling suggest that the distribution of endemic species is influenced by a combination of climatic and non-climatic variables. Soil type, temperature annual range and precipitation of the driest month were the most important predictor variables. Overlaying the potential distributions of the seven selected species indicated two areas of abundance of endemic species – these should be given attention for conservation. Endemic species are not well protected in southern Mozambique – their sampled and potential habitats are largely outside protected areas. Hence, additional reserves should be created to improve their protection. Most endemic and near-endemics species were found in the south, from Ponta de Ouro (Matutuine, south of Maputo Province) to Manhica district (north of the Maputo Province) forming part of the Maputaland Centre of Endemism. A second concentration of endemism was found in the Inhambane Province, specifically the Inhassoro and Vilanculos districts. This is proposed to be an Important Plants Area (IPA). Because most endemics and near-endemics are found in the Coastal Forest, their main threat is harvesting for charcoal production, although none of the endemic species are specifically targeted for charcoal production. In Inhambane they are also threatened by the tourism industry, agriculture and settlements. The impact of the habitat destruction on endemic species is expected to cause severe declines in the near future. The tourism industry and harvesting of trees for charcoal production and over-frequent fires are the main drivers of vegetation loss in this region. Shifting agriculture, harvesting for firewood and construction materials, cattle grazing (at a minor scale) are also impacts, but these were only observed in a small area of Maputo Province. Although the study was done in coastal zone of southern Mozambique, effective management of whole coastal zone of the country will be required to maintain a functioning and diverse ecosystem. Priorities for management are to ensure that forests are protected, in particular, Dune Forest. Actions are required to minimise degradation of coastal vegetation. Further research on Coastal Forest restoration should be planned, as field observations in this study confirm that forest in the coastal zone of southern Mozambique has resilience.
- Full Text:
- Date Issued: 2019
- Authors: Massingue, Alice Obed
- Date: 2019
- Subjects: Coastal plants -- Mozambique , Coastal plants Marine biodiversity -- Mozambique Coastal biodiversity -- Mozambique
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10948/40988 , vital:36280
- Description: This study considered aspects of the vegetation of the coastal zone of southern Mozambique, an area with a rich biodiversity. The vegetation and flora were assessed in their current state including the associated anthropogenic pressures. The environmental conditions that determined the distribution of the vegetation were evaluated. A hierarchical classification, description and ecological interpretation of the vegetation and flora of the coastal zone in southern Mozambique are presented. Analysis was based on 242 sample quadrats that were distributed in a stratified manner throughout the study area. The vegetation could be grouped into six distinct types of vegetation: Dune Forest, Coastal Forest, Coastal Grassland, Coastal Miombo, Coastal Savanna and Coastal Woodland. Species diversity was high for the all the vegetation types, particularly in the woody elements. A total of 673 species in 410 genera was recorded. They represented 104 families with Fabaceae and Rubiaceae being the most common. Of these, 6.6% were endemic or near-endemic to the coastal zone of southern Mozambique with Coastal Forest being the habitat with the greatest endemism. All soils from different vegetation types had poor agricultural potential. Soil properties were the strongest defining environmental feature separating the vegetation types: e.g. pH was high in Dune Forest compared to the others. Results from Maxent modelling suggest that the distribution of endemic species is influenced by a combination of climatic and non-climatic variables. Soil type, temperature annual range and precipitation of the driest month were the most important predictor variables. Overlaying the potential distributions of the seven selected species indicated two areas of abundance of endemic species – these should be given attention for conservation. Endemic species are not well protected in southern Mozambique – their sampled and potential habitats are largely outside protected areas. Hence, additional reserves should be created to improve their protection. Most endemic and near-endemics species were found in the south, from Ponta de Ouro (Matutuine, south of Maputo Province) to Manhica district (north of the Maputo Province) forming part of the Maputaland Centre of Endemism. A second concentration of endemism was found in the Inhambane Province, specifically the Inhassoro and Vilanculos districts. This is proposed to be an Important Plants Area (IPA). Because most endemics and near-endemics are found in the Coastal Forest, their main threat is harvesting for charcoal production, although none of the endemic species are specifically targeted for charcoal production. In Inhambane they are also threatened by the tourism industry, agriculture and settlements. The impact of the habitat destruction on endemic species is expected to cause severe declines in the near future. The tourism industry and harvesting of trees for charcoal production and over-frequent fires are the main drivers of vegetation loss in this region. Shifting agriculture, harvesting for firewood and construction materials, cattle grazing (at a minor scale) are also impacts, but these were only observed in a small area of Maputo Province. Although the study was done in coastal zone of southern Mozambique, effective management of whole coastal zone of the country will be required to maintain a functioning and diverse ecosystem. Priorities for management are to ensure that forests are protected, in particular, Dune Forest. Actions are required to minimise degradation of coastal vegetation. Further research on Coastal Forest restoration should be planned, as field observations in this study confirm that forest in the coastal zone of southern Mozambique has resilience.
- Full Text:
- Date Issued: 2019
Educators and school governing bodies’ perceptions on rationalisation and redeployment in the Alfred-Nzo West District: advancing an argument for policy change
- Authors: Mgojo, Vuyani Sybriel
- Date: 2019
- Subjects: Schools boards School administrators School management and organization
- Language: English
- Type: Thesis , Doctoral , PhD (Education)
- Identifier: http://hdl.handle.net/10353/16643 , vital:40739
- Description: The focus of this study was to report on the exploration of educators and school governing body members’ perceptions on the aspects of rationalisation and redeployment in the Alfred Nzo West District. In 1996 the Department introduced a policy on rationalisation and redeployment of teachers, based on Resolution 3 of the Education Labour Relations Council (ELRC) with the aim of phasing in a learner – teacher ratio of 40:1 in primary schools and 35:1 in high schools. A case study design using a qualitative approach was adopted for the study. Data was gathered from ten purposively selected participants using semi-structured interviews, observations and documents reviews. A thematic approach was followed for the data analysis of this study. The overall findings of the study showed that the Department of Education followed a top-down approach with no interactive communication and consultation with school stakeholders during the implementation process of this policy. Participants cast doubt on principals’ understanding when implementing this policy, which inevitably leads to low morale, anxiety and uncertainty amongst teachers. It appears that this policy has not been internalized as an instrument to promote quality and access to schools, as it has been argued that the implementation thereof has resulted in lack of physical and human resources which is compromising the quality of teaching and learning. Moreover, participants were ambivalent about rationalisation and redeployment as an enabler and as a barrier to improvement as some participants view it as an alternative to retrenchment and a cost saving measure for the Department of Education. Given the aforementioned findings, it can be concluded that if the aims of rationalisation and redeployment are to be achieved, there is a need for policy change
- Full Text:
- Date Issued: 2019
- Authors: Mgojo, Vuyani Sybriel
- Date: 2019
- Subjects: Schools boards School administrators School management and organization
- Language: English
- Type: Thesis , Doctoral , PhD (Education)
- Identifier: http://hdl.handle.net/10353/16643 , vital:40739
- Description: The focus of this study was to report on the exploration of educators and school governing body members’ perceptions on the aspects of rationalisation and redeployment in the Alfred Nzo West District. In 1996 the Department introduced a policy on rationalisation and redeployment of teachers, based on Resolution 3 of the Education Labour Relations Council (ELRC) with the aim of phasing in a learner – teacher ratio of 40:1 in primary schools and 35:1 in high schools. A case study design using a qualitative approach was adopted for the study. Data was gathered from ten purposively selected participants using semi-structured interviews, observations and documents reviews. A thematic approach was followed for the data analysis of this study. The overall findings of the study showed that the Department of Education followed a top-down approach with no interactive communication and consultation with school stakeholders during the implementation process of this policy. Participants cast doubt on principals’ understanding when implementing this policy, which inevitably leads to low morale, anxiety and uncertainty amongst teachers. It appears that this policy has not been internalized as an instrument to promote quality and access to schools, as it has been argued that the implementation thereof has resulted in lack of physical and human resources which is compromising the quality of teaching and learning. Moreover, participants were ambivalent about rationalisation and redeployment as an enabler and as a barrier to improvement as some participants view it as an alternative to retrenchment and a cost saving measure for the Department of Education. Given the aforementioned findings, it can be concluded that if the aims of rationalisation and redeployment are to be achieved, there is a need for policy change
- Full Text:
- Date Issued: 2019
Effect of service and collaborative learning strategies on students’ environmental knowledge in selected junior secondary schools in Oyo State, Nigeria
- Authors: Alalade, Olufiropo Emmanuel
- Date: 2019
- Subjects: Service learning Environmental management
- Language: English
- Type: Thesis , Doctoral , PhD (Education)
- Identifier: http://hdl.handle.net/10353/16602 , vital:40736
- Description: Though many strategies have helped in increasing students’ knowledge and awareness about environmental issues, yet, environmental challenges and problems are still on the increase in Nigeria. This may be due to the fact that environmental issues are controversial and require collaborative efforts of all citizens, especially school students. This study determined the effects of service learning and collaborative learning in social studies on Junior Secondary School students’ environmental literacy. It also explored the moderating effects of school location and gender. The study adopted a pretest-posttest, control group, quasiexperimental design. Multi-stage sampling technique was employed. Six (6) secondary schools that are co-educational from Ibadan were purposively selected based on presence of environmental challenges in their immediate environment. There were three (3) schools from Ibadan city (urban area of Ibadan) and three (3) from Ibadan less city (rural area of Ibadan). Seven hypotheses were tested at 0.05 level of significance. Five research instruments were used for the study, these were; Environmental Knowledge Test (EKT, r = 0.76), Environmental Attitude Questionnaire (EAQ, r = 0.85), Service Learning Guide (SLG, r = 0.71), Collaborative Learning Guide (CLG, r = 0.66) and Conventional Learning Guide (CLG, r = 0.73). Analysis of Covariance (ANCOVA) was used in testing the seven formulated hypotheses. Scheffé Post-hoc analysis was carried out to determine the source of significant effect of treatment. Significant interaction effect was described using graphical representation. All hypotheses were tested at P< .05 level of significance. The results revealed that there was a significant main effect of treatment (service and collaborative learning strategies) on junior secondary school students’ environmental knowledge (F(2,582) = 824.98; p<0.05, partial η2 = 0.739), with an effect of 73.9%. There was also a significant main effect of treatment (service and collaborative learning strategies) on junior secondary school students’ environmental attitude (F(2,582) = 1317.79; p<0.05, partial η2 = 0.819). The findings showed that there was a significant main effect of gender (male/female) on junior secondary school students’ environmental knowledge (F(1,582) = 3.99; p<0.05, v partial η2 = 0.007) but there was no significant main effect of school location (urban/rural) on junior secondary school students’ environmental knowledge (F(1,582) = 0.08; p>.05, partial η2 = 0.00). Based on these findings, it was recommended that teachers should adopt service learning and collaborative learning strategies in the teaching of environmental concepts and problems in Social Studies in order to improve students’ performance in Social Studies. Teachers should facilitate the use of service learning and collaborative learning strategies in schools to improve students’ environmental problem-solving skills and their achievement in the subject. Teaching institutions should not only include service learning and collaborative learning strategies in their curriculum but should endeavour to provide practical experience for pre-service teachers to be well grounded and equipped on the use of these strategies.
- Full Text:
- Date Issued: 2019
- Authors: Alalade, Olufiropo Emmanuel
- Date: 2019
- Subjects: Service learning Environmental management
- Language: English
- Type: Thesis , Doctoral , PhD (Education)
- Identifier: http://hdl.handle.net/10353/16602 , vital:40736
- Description: Though many strategies have helped in increasing students’ knowledge and awareness about environmental issues, yet, environmental challenges and problems are still on the increase in Nigeria. This may be due to the fact that environmental issues are controversial and require collaborative efforts of all citizens, especially school students. This study determined the effects of service learning and collaborative learning in social studies on Junior Secondary School students’ environmental literacy. It also explored the moderating effects of school location and gender. The study adopted a pretest-posttest, control group, quasiexperimental design. Multi-stage sampling technique was employed. Six (6) secondary schools that are co-educational from Ibadan were purposively selected based on presence of environmental challenges in their immediate environment. There were three (3) schools from Ibadan city (urban area of Ibadan) and three (3) from Ibadan less city (rural area of Ibadan). Seven hypotheses were tested at 0.05 level of significance. Five research instruments were used for the study, these were; Environmental Knowledge Test (EKT, r = 0.76), Environmental Attitude Questionnaire (EAQ, r = 0.85), Service Learning Guide (SLG, r = 0.71), Collaborative Learning Guide (CLG, r = 0.66) and Conventional Learning Guide (CLG, r = 0.73). Analysis of Covariance (ANCOVA) was used in testing the seven formulated hypotheses. Scheffé Post-hoc analysis was carried out to determine the source of significant effect of treatment. Significant interaction effect was described using graphical representation. All hypotheses were tested at P< .05 level of significance. The results revealed that there was a significant main effect of treatment (service and collaborative learning strategies) on junior secondary school students’ environmental knowledge (F(2,582) = 824.98; p<0.05, partial η2 = 0.739), with an effect of 73.9%. There was also a significant main effect of treatment (service and collaborative learning strategies) on junior secondary school students’ environmental attitude (F(2,582) = 1317.79; p<0.05, partial η2 = 0.819). The findings showed that there was a significant main effect of gender (male/female) on junior secondary school students’ environmental knowledge (F(1,582) = 3.99; p<0.05, v partial η2 = 0.007) but there was no significant main effect of school location (urban/rural) on junior secondary school students’ environmental knowledge (F(1,582) = 0.08; p>.05, partial η2 = 0.00). Based on these findings, it was recommended that teachers should adopt service learning and collaborative learning strategies in the teaching of environmental concepts and problems in Social Studies in order to improve students’ performance in Social Studies. Teachers should facilitate the use of service learning and collaborative learning strategies in schools to improve students’ environmental problem-solving skills and their achievement in the subject. Teaching institutions should not only include service learning and collaborative learning strategies in their curriculum but should endeavour to provide practical experience for pre-service teachers to be well grounded and equipped on the use of these strategies.
- Full Text:
- Date Issued: 2019
Effect of social capital and information acquisition on the adoption and benefits of conservation agriculture among cassava and maize smallholder farmers in South-West Nigeria
- Authors: Olawuyi, Seyi Olalekan
- Date: 2019
- Subjects: Agricultural conservation Sustainable agriculture Farms, Small|
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10353/15200 , vital:40200
- Description: Sustainable economic growth and development in developing economy like Nigeria is achievable through the agricultural sector and sub-sectors which are concentrated in rural areas. Rural areas represent a home to majority (about 75%) of the households practicing farming for family sustenance and/or to earn income from the sales of agricultural products (Oyakhilomen and Zibah, 2014). In addition to the persistent use of traditional farming practices, these rural farming households cultivate crops varieties that are low-yielding on small and scattered farmland holdings (smallholder farmers) (Oyakhilomen and Zibah, 2014). This act depletes the soil organic matter with devastating consequences on production output, income generation as well as the ecosystem. Similarly, non-access to agricultural credit and limited technical knowhow are parts of the challenges that are facing the development of farming activities in subSaharan Africa, including Nigeria (Kassie, Pender, Yesuf, Köhlin, Bluffstone and Mulugeta, 2008). These challenges call for holistic interventions such as conservative agricultural practices; which are sustainable, promote safe environment and ultimately increase production output.
- Full Text:
- Date Issued: 2019
- Authors: Olawuyi, Seyi Olalekan
- Date: 2019
- Subjects: Agricultural conservation Sustainable agriculture Farms, Small|
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10353/15200 , vital:40200
- Description: Sustainable economic growth and development in developing economy like Nigeria is achievable through the agricultural sector and sub-sectors which are concentrated in rural areas. Rural areas represent a home to majority (about 75%) of the households practicing farming for family sustenance and/or to earn income from the sales of agricultural products (Oyakhilomen and Zibah, 2014). In addition to the persistent use of traditional farming practices, these rural farming households cultivate crops varieties that are low-yielding on small and scattered farmland holdings (smallholder farmers) (Oyakhilomen and Zibah, 2014). This act depletes the soil organic matter with devastating consequences on production output, income generation as well as the ecosystem. Similarly, non-access to agricultural credit and limited technical knowhow are parts of the challenges that are facing the development of farming activities in subSaharan Africa, including Nigeria (Kassie, Pender, Yesuf, Köhlin, Bluffstone and Mulugeta, 2008). These challenges call for holistic interventions such as conservative agricultural practices; which are sustainable, promote safe environment and ultimately increase production output.
- Full Text:
- Date Issued: 2019
Effects of 99-year leases on newly resettled farmers’ farm improvement, productivity and empowerment in Zimbabwe, 2007 to 2013
- Authors: Makaye, Peter
- Date: 2019
- Subjects: Land reform - -Zimbabwe , Land tenure -- Zimbabwe Farmers -- Zimbabwe Sustainable development -- Zimbabwe
- Language: English
- Type: Thesis , Doctoral , DPhil
- Identifier: http://hdl.handle.net/10948/40812 , vital:36239
- Description: This study seeks to interrogate the effects of 99-year leases on newly resettled farmers, with focus on Zimbabwe’s Fast Track Land Reform programme, shifting from its causes and processes to its variegated outcomes., The focus was on how the leasehold system has impinged on three variables: farm improvement, productivity, and empowerment. Quantitative data was collected from 92 newly resettled farmers randomly selected from three different farming regions in Zimbabwe: Region 2, an agriculturally well-endowed area concentrating on crop production, Region 4, an arid and hot region concentrating on livestock, and Region 5, specialising in sugar cane production under irrigation. To corroborate the survey findings, follow-up interviews and focus group discussions (FGDs) were carried out in these regions. Interviews with purposively sampled experts in agriculture in Zimbabwe were also conducted. Data are presented in charts and graphs as well as detailed descriptions. The study found that the 99-year leases influenced the fortunes of the farmers in different ways. In some areas, depending on the crop grown, the 99-year leases were accepted as a basis for a loan. In other instances, the leases have not been accepted as collateral and this has constrained the farmers’ ability to optimally utilise their farms optimally. Despite a general sense of insecurity, the farmers have shown a willingness to re-invest in the farms., Many improvements such as new accommodation for employees, the erection of fire guards, and the development of water sources are being made on the farms, all pointing to a desire for sustained utilisation of the A2 farms. The researcher proposes that serious effort has to be made towards making the 99-year leases acceptable as collateral for loans because otherwise, in the context of general undercapitalisation among the farmers, their ability to make the medium-scale farms optimally contribute to national accumulation will remain constrained. The form of tenure is related to the empowerment of the farmers, both materially and socially. This is in turn related to the sustainable use of the land and hence to sustainable development in Zimbabwe.
- Full Text:
- Date Issued: 2019
- Authors: Makaye, Peter
- Date: 2019
- Subjects: Land reform - -Zimbabwe , Land tenure -- Zimbabwe Farmers -- Zimbabwe Sustainable development -- Zimbabwe
- Language: English
- Type: Thesis , Doctoral , DPhil
- Identifier: http://hdl.handle.net/10948/40812 , vital:36239
- Description: This study seeks to interrogate the effects of 99-year leases on newly resettled farmers, with focus on Zimbabwe’s Fast Track Land Reform programme, shifting from its causes and processes to its variegated outcomes., The focus was on how the leasehold system has impinged on three variables: farm improvement, productivity, and empowerment. Quantitative data was collected from 92 newly resettled farmers randomly selected from three different farming regions in Zimbabwe: Region 2, an agriculturally well-endowed area concentrating on crop production, Region 4, an arid and hot region concentrating on livestock, and Region 5, specialising in sugar cane production under irrigation. To corroborate the survey findings, follow-up interviews and focus group discussions (FGDs) were carried out in these regions. Interviews with purposively sampled experts in agriculture in Zimbabwe were also conducted. Data are presented in charts and graphs as well as detailed descriptions. The study found that the 99-year leases influenced the fortunes of the farmers in different ways. In some areas, depending on the crop grown, the 99-year leases were accepted as a basis for a loan. In other instances, the leases have not been accepted as collateral and this has constrained the farmers’ ability to optimally utilise their farms optimally. Despite a general sense of insecurity, the farmers have shown a willingness to re-invest in the farms., Many improvements such as new accommodation for employees, the erection of fire guards, and the development of water sources are being made on the farms, all pointing to a desire for sustained utilisation of the A2 farms. The researcher proposes that serious effort has to be made towards making the 99-year leases acceptable as collateral for loans because otherwise, in the context of general undercapitalisation among the farmers, their ability to make the medium-scale farms optimally contribute to national accumulation will remain constrained. The form of tenure is related to the empowerment of the farmers, both materially and socially. This is in turn related to the sustainable use of the land and hence to sustainable development in Zimbabwe.
- Full Text:
- Date Issued: 2019
Effects of Isixhosa and English versions of GeoGebra on geometry achievement
- Authors: Matsha, Vuyani Hodecius
- Date: 2019
- Subjects: Mathematics -- Study and teaching , Mathematics Multicultural education -- South Africa -- Eastern Cape Academic achievement Language and languages
- Language: English
- Type: Thesis , Doctoral , DEd
- Identifier: http://hdl.handle.net/10948/41032 , vital:36284
- Description: The purpose of this study was to investigate the effects of using GeoGebra in different linguistic situations, namely isiXhosa and English, in township schools in Port Elizabeth. The objectives were to design an isiXhosa version of GeoGebra and investigate whether or not using it in first and second languages would offer any different results with regard to achievement in, and visuospatial ability of, geometry. Learners and teachers’ perceptions of the GeoGebra software were investigated within the framework of these variables. A pre-post-test, mixed method, concurrent, embedded triangulation research design was used with qualitative aspects playing a more prominent role than the quantitative data. Data collection strategies included baseline assessment to determine teachers’ perceptions of their ability to work with GeoGebra, focus group interviews with learners, semi-structured interviews with teachers, classroom observation and learners’ geometry tests. The study used Vygotsky’s socio-cultural model as a philosophical framework, while the explanatory framework of this study was situated within Baddeley’s revised model of working memory. The translation of GeoGebra from English to isiXhosa proved to be successful in terms of user responses and the fact that it is the first official African language of this dynamic software to be published, offered and made available online. Pre-post geometry testing revealed that for all the groups, the section on riders displayed the largest mean increase. Performance on the riders, which were aligned to the Curriculum Assessment Policy Statement (CAPS) grade 10 examination papers, can be viewed as an indicator of visuospatial ability. Importantly, the mean scores of the learners using the isiXhosa version of GeoGebra improved more in terms of practical significance (effect size = 0,78 for Riders) than the improvement in scores of learners who used the English version (Effect size = 0,61 for Riders). The total effect sizes of the isiXhosa and English groups were 0,69 and 0,36 respectively. This finding seems to resonate with the findings that language proficiency is an indicator of mathematical achievement. This is so in spite of the small size of the sample because the main purpose of the study was to obtain a brief impression (snapshot) of the situation regarding language issues involved when learning mathematics via the software GeoGebra.
- Full Text:
- Date Issued: 2019
- Authors: Matsha, Vuyani Hodecius
- Date: 2019
- Subjects: Mathematics -- Study and teaching , Mathematics Multicultural education -- South Africa -- Eastern Cape Academic achievement Language and languages
- Language: English
- Type: Thesis , Doctoral , DEd
- Identifier: http://hdl.handle.net/10948/41032 , vital:36284
- Description: The purpose of this study was to investigate the effects of using GeoGebra in different linguistic situations, namely isiXhosa and English, in township schools in Port Elizabeth. The objectives were to design an isiXhosa version of GeoGebra and investigate whether or not using it in first and second languages would offer any different results with regard to achievement in, and visuospatial ability of, geometry. Learners and teachers’ perceptions of the GeoGebra software were investigated within the framework of these variables. A pre-post-test, mixed method, concurrent, embedded triangulation research design was used with qualitative aspects playing a more prominent role than the quantitative data. Data collection strategies included baseline assessment to determine teachers’ perceptions of their ability to work with GeoGebra, focus group interviews with learners, semi-structured interviews with teachers, classroom observation and learners’ geometry tests. The study used Vygotsky’s socio-cultural model as a philosophical framework, while the explanatory framework of this study was situated within Baddeley’s revised model of working memory. The translation of GeoGebra from English to isiXhosa proved to be successful in terms of user responses and the fact that it is the first official African language of this dynamic software to be published, offered and made available online. Pre-post geometry testing revealed that for all the groups, the section on riders displayed the largest mean increase. Performance on the riders, which were aligned to the Curriculum Assessment Policy Statement (CAPS) grade 10 examination papers, can be viewed as an indicator of visuospatial ability. Importantly, the mean scores of the learners using the isiXhosa version of GeoGebra improved more in terms of practical significance (effect size = 0,78 for Riders) than the improvement in scores of learners who used the English version (Effect size = 0,61 for Riders). The total effect sizes of the isiXhosa and English groups were 0,69 and 0,36 respectively. This finding seems to resonate with the findings that language proficiency is an indicator of mathematical achievement. This is so in spite of the small size of the sample because the main purpose of the study was to obtain a brief impression (snapshot) of the situation regarding language issues involved when learning mathematics via the software GeoGebra.
- Full Text:
- Date Issued: 2019
Effects of pre-slaughter stress, sex and breed on blood stress indicators, heat shock proteins, glycolytic potential and lamb quality
- Authors: Stempa ,Thuthuzelwa
- Date: 2019
- Subjects: Animal welfare Meat--Quality
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10353/15376 , vital:40402
- Description: The main objective of this study was to determine the effects of pre-slaughter stress (transportation distance and lairage duration), sex and breed on blood stress indicators, heat shock proteins, post-mortem muscle metabolites (glycogen, glucose, glucose-6-phosphate and lactate), glycolytic potential and meat quality attributes from lambs slaughtered at a commercial abattoir. The study was conducted in a high-throughput commercial abattoir in the Buffalo City local municipality of the Eastern Cape Province, South Africa. A total of a hundred eight-month old Dorper and Merino lambs, both male and female, were used in the study. Blood samples for the analysis of glucose and lactate levels were collected using 10.0 mL disposable Becton Dickinson vacutainer tubes treated with fluoride oxalate (grey top) whereas those for determination of cortisol and heat shock protein 70 (HSPA1A) levels were collected using plasma separating vacutainer tubes (SSTTMII, gold top), and those for analysis of creatine kinase and lactate dehydrogenase were collected using 10.0 ml vacutainer tubes treated with Ethylenediaminetetraacetic acid (EDTA). Meat samples (~50 g) for the measurement of post-mortem energy metabolites (glycogen, lactate glucose-6-phosphate and glucose content) were collected from the Muscularis longimissius thoracis et lumborum (LTL) of each carcass ~30 minutes after slaughter and immediately frozen in liquid nitrogen (-196 oC) to prevent further glycolysis. Cold carcass weight (CCW), warm carcass weight (WCW) and carcass fatness (CF) was measured. Meat pH and temperature were measured at iii 45 minutes (initial pH), 6 hours and 24 hours ultimate pH (pHu) post-mortem. Meat colour coordinates [lightness (L*), redness (a*), yellowness (b*), hue angle (H*), chroma (C*)] were also measured 24 hours after slaughter. Furthermore, thawing loss (TL%), cooking loss (CL%) and warner braztler shear force (WBSF) was measured in the LTL 7 days post slaughter. Breed had a significant effect on plasma HSPA1A, plasma lactate, WCW, CCW, L*, muscle glycogen and WBSF. Sex had a significant effect on plasma HSPA1A and pHu. Pearson‘s correlations showed that meat muscle glycogen was positively correlated to glycolytic potential (P<0.001; r=0.63) and initial pH (P<0.05, r=0.20). Muscle lactate was positively correlated to muscle glucose (P<0.01, r=0.30) and glycolytic potential (P<0.001, r=0.79). A positive correlation was shown between muscle glucose and glycolytic potential (P<0.05, r=0.23). The level of LDH was affected by the distance travelled by lambs prior to slaughter. Lairage duration did not affect the levels of CK and LDH. Principal Component Analysis showed a relationship between distance travelled and CK and LDH; and that CK and LDH also influenced the quality of meat from lambs. With respect to sex and breed, the results indicate that female and Dorper were more stressed than male and Merino respectively. Muscle glycolytic potential and post-mortem metabolites have an impact on the quality of meat produced and the Merino had higher muscle glycogen levels at slaughter; hence they produced better meat quality compared to the Dorper. Moreover, no associations were seen between pHu and blood stress indicators. These results indicate that blood stress indicators at exsanguination cannot be used as useful indicators of dark cutting condition in lamb. A relationship between pHu, muscle glycogen and glycolytic potential was established and thus meat pHu can be used as a reliable indicator of tenderness in lamb.
- Full Text:
- Date Issued: 2019
- Authors: Stempa ,Thuthuzelwa
- Date: 2019
- Subjects: Animal welfare Meat--Quality
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10353/15376 , vital:40402
- Description: The main objective of this study was to determine the effects of pre-slaughter stress (transportation distance and lairage duration), sex and breed on blood stress indicators, heat shock proteins, post-mortem muscle metabolites (glycogen, glucose, glucose-6-phosphate and lactate), glycolytic potential and meat quality attributes from lambs slaughtered at a commercial abattoir. The study was conducted in a high-throughput commercial abattoir in the Buffalo City local municipality of the Eastern Cape Province, South Africa. A total of a hundred eight-month old Dorper and Merino lambs, both male and female, were used in the study. Blood samples for the analysis of glucose and lactate levels were collected using 10.0 mL disposable Becton Dickinson vacutainer tubes treated with fluoride oxalate (grey top) whereas those for determination of cortisol and heat shock protein 70 (HSPA1A) levels were collected using plasma separating vacutainer tubes (SSTTMII, gold top), and those for analysis of creatine kinase and lactate dehydrogenase were collected using 10.0 ml vacutainer tubes treated with Ethylenediaminetetraacetic acid (EDTA). Meat samples (~50 g) for the measurement of post-mortem energy metabolites (glycogen, lactate glucose-6-phosphate and glucose content) were collected from the Muscularis longimissius thoracis et lumborum (LTL) of each carcass ~30 minutes after slaughter and immediately frozen in liquid nitrogen (-196 oC) to prevent further glycolysis. Cold carcass weight (CCW), warm carcass weight (WCW) and carcass fatness (CF) was measured. Meat pH and temperature were measured at iii 45 minutes (initial pH), 6 hours and 24 hours ultimate pH (pHu) post-mortem. Meat colour coordinates [lightness (L*), redness (a*), yellowness (b*), hue angle (H*), chroma (C*)] were also measured 24 hours after slaughter. Furthermore, thawing loss (TL%), cooking loss (CL%) and warner braztler shear force (WBSF) was measured in the LTL 7 days post slaughter. Breed had a significant effect on plasma HSPA1A, plasma lactate, WCW, CCW, L*, muscle glycogen and WBSF. Sex had a significant effect on plasma HSPA1A and pHu. Pearson‘s correlations showed that meat muscle glycogen was positively correlated to glycolytic potential (P<0.001; r=0.63) and initial pH (P<0.05, r=0.20). Muscle lactate was positively correlated to muscle glucose (P<0.01, r=0.30) and glycolytic potential (P<0.001, r=0.79). A positive correlation was shown between muscle glucose and glycolytic potential (P<0.05, r=0.23). The level of LDH was affected by the distance travelled by lambs prior to slaughter. Lairage duration did not affect the levels of CK and LDH. Principal Component Analysis showed a relationship between distance travelled and CK and LDH; and that CK and LDH also influenced the quality of meat from lambs. With respect to sex and breed, the results indicate that female and Dorper were more stressed than male and Merino respectively. Muscle glycolytic potential and post-mortem metabolites have an impact on the quality of meat produced and the Merino had higher muscle glycogen levels at slaughter; hence they produced better meat quality compared to the Dorper. Moreover, no associations were seen between pHu and blood stress indicators. These results indicate that blood stress indicators at exsanguination cannot be used as useful indicators of dark cutting condition in lamb. A relationship between pHu, muscle glycogen and glycolytic potential was established and thus meat pHu can be used as a reliable indicator of tenderness in lamb.
- Full Text:
- Date Issued: 2019
Efficacy, acceptability and feasibility of mhealth technology in promoting adherence to anti-diabetic therapy and glycaemic control among diabetic patients in Eastern Cape, South Africa”
- Authors: Owolabi, Eyitayo Omolara
- Date: 2019
- Subjects: Diabetes
- Language: English
- Type: Thesis , Doctoral , PhD (Nursing)
- Identifier: http://hdl.handle.net/10353/16792 , vital:40774
- Description: Background: Diabetes mellitus is a disease of a significant public health concern and a leading cause of death and disability worldwide. In Africa, South Africa ranks second among countries with the highest burden of diabetes, and with a poor level of glycaemic control. mHealth technology is an innovative and cost-effective measure of promoting health and the use of text messaging for fostering health is evolving. In South Africa, there is hardly any study involving the use of mobile health technology, including text messaging for promoting health among diabetic patients. Purpose: The aim of this study was to determine the efficacy, feasibility and acceptability of mHealth in promoting adherence and glycaemic control among diabetic patients in resource-poor settings of the Eastern Cape Province of South Africa. Also, the study assessed the impact of text messaging on knowledge, selfmanagement behaviour, self-efficacy and health-related quality of life. Methodology: The study adopted a multi-centre, two-arm, parallel, randomised controlled trial design. Participants were randomly assigned to the intervention (n=108) and control arm (n=108). Participants’ socio-demographic information was obtained using the widely validated WHO STEPwise questionnaire, and a selfdeveloped questionnaire, including previously validated measurement scales were used to obtain information on adherence, self-management behaviour, self-efficacy and health-related quality of life. Participants in the intervention arm received daily text messages related to diabetes management and care for six months. Data were collected at baseline and six months post-intervention. Blood glucose, blood pressure and anthropometric measurements followed standard procedure. Mixed-model analysis was used to assess the impact of the SMS on random blood glucose while xi | P a g e linear and bivariate logistic regression were used to assess for effect on other clinical outcomes. Results: The mean age of the participants was 60.64 (SD± 11.58) years. The majority of the study participants had secondary level of education (95.3%) and earned 1500 to 14200 Rand per month (67.7%). For both the intervention and the control group, majority never used tobacco (98.10% vs 94.40%) or alcohol (88.00% vs 87.00%). Both arms of the study showed improvement in the primary outcome (blood glucose level), with no significant difference, the mean adjusted difference in blood glucose from baseline to six months post-intervention was 0.26 (-0.81 to 1.32), p=0.634. Also, the intervention did not have a significant effect on the secondary outcomes (knowledge, medication adherence, dietary adherence, adherence to physical activity, healthrelated quality of life, self-management behaviour and diabetes distress). Similarly, the intervention did not have any significant effect on secondary clinical outcomes such as weight (p=0.654), body mass index (p=0.439), systolic (p=0.610) and diastolic blood pressure (p=0.535). An overwhelming majority of the participants (90.74%) were pleased with the intervention and felt it was helpful. Of those who took part in the intervention, 91% completed the follow-up study after six months. Conclusion: The use of SMS is a highly acceptable and feasible adjunct to standard clinical care in the promotion of health among diabetic patients in this study setting. Although there was a little improvement, the efficacy of a unidirectional text messaging in promoting health outcomes in this study setting is still doubt
- Full Text:
- Date Issued: 2019
- Authors: Owolabi, Eyitayo Omolara
- Date: 2019
- Subjects: Diabetes
- Language: English
- Type: Thesis , Doctoral , PhD (Nursing)
- Identifier: http://hdl.handle.net/10353/16792 , vital:40774
- Description: Background: Diabetes mellitus is a disease of a significant public health concern and a leading cause of death and disability worldwide. In Africa, South Africa ranks second among countries with the highest burden of diabetes, and with a poor level of glycaemic control. mHealth technology is an innovative and cost-effective measure of promoting health and the use of text messaging for fostering health is evolving. In South Africa, there is hardly any study involving the use of mobile health technology, including text messaging for promoting health among diabetic patients. Purpose: The aim of this study was to determine the efficacy, feasibility and acceptability of mHealth in promoting adherence and glycaemic control among diabetic patients in resource-poor settings of the Eastern Cape Province of South Africa. Also, the study assessed the impact of text messaging on knowledge, selfmanagement behaviour, self-efficacy and health-related quality of life. Methodology: The study adopted a multi-centre, two-arm, parallel, randomised controlled trial design. Participants were randomly assigned to the intervention (n=108) and control arm (n=108). Participants’ socio-demographic information was obtained using the widely validated WHO STEPwise questionnaire, and a selfdeveloped questionnaire, including previously validated measurement scales were used to obtain information on adherence, self-management behaviour, self-efficacy and health-related quality of life. Participants in the intervention arm received daily text messages related to diabetes management and care for six months. Data were collected at baseline and six months post-intervention. Blood glucose, blood pressure and anthropometric measurements followed standard procedure. Mixed-model analysis was used to assess the impact of the SMS on random blood glucose while xi | P a g e linear and bivariate logistic regression were used to assess for effect on other clinical outcomes. Results: The mean age of the participants was 60.64 (SD± 11.58) years. The majority of the study participants had secondary level of education (95.3%) and earned 1500 to 14200 Rand per month (67.7%). For both the intervention and the control group, majority never used tobacco (98.10% vs 94.40%) or alcohol (88.00% vs 87.00%). Both arms of the study showed improvement in the primary outcome (blood glucose level), with no significant difference, the mean adjusted difference in blood glucose from baseline to six months post-intervention was 0.26 (-0.81 to 1.32), p=0.634. Also, the intervention did not have a significant effect on the secondary outcomes (knowledge, medication adherence, dietary adherence, adherence to physical activity, healthrelated quality of life, self-management behaviour and diabetes distress). Similarly, the intervention did not have any significant effect on secondary clinical outcomes such as weight (p=0.654), body mass index (p=0.439), systolic (p=0.610) and diastolic blood pressure (p=0.535). An overwhelming majority of the participants (90.74%) were pleased with the intervention and felt it was helpful. Of those who took part in the intervention, 91% completed the follow-up study after six months. Conclusion: The use of SMS is a highly acceptable and feasible adjunct to standard clinical care in the promotion of health among diabetic patients in this study setting. Although there was a little improvement, the efficacy of a unidirectional text messaging in promoting health outcomes in this study setting is still doubt
- Full Text:
- Date Issued: 2019
Elasticity of the South African economy towards portfolio investments in BRICS countries
- Authors: Taonezvi, Lovemore
- Date: 2019
- Subjects: Economic development -- South Africa
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10948/44537 , vital:38141
- Description: The emerging economies of Brazil, Russia, India, and China (BRIC) have been experiencing high growth rates since the turn of the millennium, whereas economic growth has been elusive in South Africa. As the newest member of BRICS, South Africa is expected to economically benefit through, amongst others, increases in capital flows, foreign investments by local firms, and increases in trade. Such benefits are anticipated to propel the country’s economic growth, thereby helping it to tackle its chronic problems of high unemployment, poverty, and economic inequality. The inclusion of South Africa in BRICS has, however, been viewed by critics as erroneous, since the country has, inter alia, poor economic growth; a small economy and population; and political instability. While foreign portfolio investment (FPI) inflows to South Africa have surged in recent years, economic growth has remained lacklustre. These flows have also faced sudden reversals, especially during the financial crisis of 2007-2009. With the potential to leverage its growth from intra-BRICS FPI inflows, it becomes of paramount significance for policymakers to have knowledge of the South African economy’s responsiveness to such inflows. With a theoretical framework based on the endogenous growth model, an augmented Cobb-Douglas production function was extended in this thesis in order to study the relationship between BRICS growth and intra-BRICS FPI in a dynamic panel data generalised method of moments (GMM) context. Similarly, the South African economy’s elasticity towards intraBRICS FPI was estimated. Vector autoregressive (VAR) analysis was used to evaluate the responsiveness of South Africa’s economy to an innovative shock to intra-BRICS FPI. Annual and quarterly data for the period 2000-2016 were used in panel data and VAR analysis, respectively. It was found that intra-BRICS FPI flows have a positive and statistically significant relationship with BRICS growth, while the elasticity of the South African economy to these flows is estimated at 0.007. Additionally, the efficiency and accessibility dimensions of financial market development do not assist FPI in promoting growth in BRICS, while financial market depth does. South Africa’s BRICS membership has a positive effect on its own growth, while for other BRICS nations, this membership is negative and insignificant. Credit rating downgrades have a negative and insignificant impact on economic growth, while the negative impact for inflation, government expenditure, and total labour employment is significant. Conversely, gross capital formation and trade openness have a positive and significant relationship with BRICS growth. The study also determined that a unit shock on intra-BRICS FPI resulted in negative fluctuations of South Africa’s economy within the first eight quarters before being positive and mostly constant thereafter. By supplementing domestic savings and facilitating the international integration of domestic financial markets, FPI promotes growth in BRICS. The short-term, ease of reversibility, and speculative nature of FPI are amongst some of the reasons for its destabilising effect on South Africa’s economy. Furthermore, inflation is a key determinant of FPI inflows to South Africa. Additional BRIC cooperation in FPI and trade; increased investments in domestic capital; reductions of inflation and corruption; investments in education and skills development; and stock market reforms are some of the recommendations for BRIC, and South Africa in particular. South Africa can consider prudential use of a mix of capital account controls, as well as fiscal and monetary policies to cushion its economy from FPI shocks in the short- to medium-term.
- Full Text:
- Date Issued: 2019
- Authors: Taonezvi, Lovemore
- Date: 2019
- Subjects: Economic development -- South Africa
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10948/44537 , vital:38141
- Description: The emerging economies of Brazil, Russia, India, and China (BRIC) have been experiencing high growth rates since the turn of the millennium, whereas economic growth has been elusive in South Africa. As the newest member of BRICS, South Africa is expected to economically benefit through, amongst others, increases in capital flows, foreign investments by local firms, and increases in trade. Such benefits are anticipated to propel the country’s economic growth, thereby helping it to tackle its chronic problems of high unemployment, poverty, and economic inequality. The inclusion of South Africa in BRICS has, however, been viewed by critics as erroneous, since the country has, inter alia, poor economic growth; a small economy and population; and political instability. While foreign portfolio investment (FPI) inflows to South Africa have surged in recent years, economic growth has remained lacklustre. These flows have also faced sudden reversals, especially during the financial crisis of 2007-2009. With the potential to leverage its growth from intra-BRICS FPI inflows, it becomes of paramount significance for policymakers to have knowledge of the South African economy’s responsiveness to such inflows. With a theoretical framework based on the endogenous growth model, an augmented Cobb-Douglas production function was extended in this thesis in order to study the relationship between BRICS growth and intra-BRICS FPI in a dynamic panel data generalised method of moments (GMM) context. Similarly, the South African economy’s elasticity towards intraBRICS FPI was estimated. Vector autoregressive (VAR) analysis was used to evaluate the responsiveness of South Africa’s economy to an innovative shock to intra-BRICS FPI. Annual and quarterly data for the period 2000-2016 were used in panel data and VAR analysis, respectively. It was found that intra-BRICS FPI flows have a positive and statistically significant relationship with BRICS growth, while the elasticity of the South African economy to these flows is estimated at 0.007. Additionally, the efficiency and accessibility dimensions of financial market development do not assist FPI in promoting growth in BRICS, while financial market depth does. South Africa’s BRICS membership has a positive effect on its own growth, while for other BRICS nations, this membership is negative and insignificant. Credit rating downgrades have a negative and insignificant impact on economic growth, while the negative impact for inflation, government expenditure, and total labour employment is significant. Conversely, gross capital formation and trade openness have a positive and significant relationship with BRICS growth. The study also determined that a unit shock on intra-BRICS FPI resulted in negative fluctuations of South Africa’s economy within the first eight quarters before being positive and mostly constant thereafter. By supplementing domestic savings and facilitating the international integration of domestic financial markets, FPI promotes growth in BRICS. The short-term, ease of reversibility, and speculative nature of FPI are amongst some of the reasons for its destabilising effect on South Africa’s economy. Furthermore, inflation is a key determinant of FPI inflows to South Africa. Additional BRIC cooperation in FPI and trade; increased investments in domestic capital; reductions of inflation and corruption; investments in education and skills development; and stock market reforms are some of the recommendations for BRIC, and South Africa in particular. South Africa can consider prudential use of a mix of capital account controls, as well as fiscal and monetary policies to cushion its economy from FPI shocks in the short- to medium-term.
- Full Text:
- Date Issued: 2019
Electrical, photo-thermal and mechanical degradation analysis of degraded single junction amorphous silicon solar modules
- Osayemwenre, Gilbert Omorodion
- Authors: Osayemwenre, Gilbert Omorodion
- Date: 2019
- Subjects: Solar cells Amorphous semiconductors Silicon
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10353/15211 , vital:40204
- Description: In this present era of sustainable energy development, photovoltaic modules which are based on amorphous silicon cells have immeasurable prospects of contributing meaningfully to the energy demand of the world at large. The global consciousness of environmental safety issues has birthed the rapid demand for the photovoltaic system. However, the production increase is mainly in bulk-type crystalline (c-Si) solar cells. Thus, to meet the high demand of the market, single junction amorphous silicon (a-Si:H) solar cells production must be encouraged through active research in that regard. This could also help to improve its efficiency and reliability. There has recently been a sharp decrease in the production cost of the bulk Si solar cell, but the a-Si:H solar cell still remains the most economically viable in comparison to the other PV technologies. Companies such as Sharp are currently developing large-scale a-Si:H solar modules that can produce an efficiency of 10.5% after the long-term degradation process. To date, a-Si:H is believed to be one of the most promising thin-film PV technologies (Saito et al., 1993; Hamakawa et al., 1994). The cost of a solar PV manufacturing fell by 6% in 2014 (Santa, 2014), this is in accordance with the 2008 cost production forecast; thus, the cost record stands at 0.20 per watt, as reported by the NPD Solar publisher. Amorphous silicon (a-Si) solar modules generate more kilowatt-hour (kWh) of electricity per kilowatt (kW) than crystalline silicon or other technologies of the same capacity of installation. Furthermore, a-Si:H modules have more functional hours per day. Single junction amorphous silicon (a-Si:H) modules can function beyond the peak sun hours, and they also have a better performance on a cloudy day. vii In other words, a 1kW PV system of a-Si:H is expected to generate more electricity per year in comparison to 1kW PV from other technologies, hence there is a low energy payback time. In this study, commercially available single junction amorphous silicon modules were bought from a local market and they were immediately deployed outdoors. The initial reading of the modules, which served as baseline reading, showed an average of 25% decrease in the modules performance, therefore, there is a need for a long term monitoring process to obtain the best and worst performing modules. Measuring the performance parameters of these PV modules under real sun light (IV) provides a better degradation assessment. This conventional assessment cannot provide an in-depth insight responsible for the variation and degradation of the performance parameters. More obscured parameters like recombination current and ideality factor were obtained from the dark IV measurements. However, this is still superficial in a way. The intrinsic parameters were obtained from scanning probe microscopy (SPM) and CV measurements. The study focuses on the degradation analysis of a-Si:H due to an increase in defect density. A rise in the defect concentration is a huge problem because it causes long-term solar cell degradation, which increases the recombination current and decreases the conversion efficiency. Furthermore, it decreases the photo-generating current and reduces the effective efficiency of the solar device. In other words, the electrical output decreases. This research investigates the reduction in a-Si:H modules’ maximum power, and correlates these with a hot spot formation. A PVPM IV tracer was used for the outdoor characterisation of the module’s temperature profile, while the IR camera was used to analyse the hot spot centre. A four probe IV/CV from NMU was used for the indoor assessment of smaller samples cleaved from both the affected and non-affected regions to characterise the electrical variations across the module viii samples. To be precise, in this study, a naturally degraded single junction amorphous silicon module was delaminated and its mechanical properties were analysed and correlated with the contact potential from a Kelvin probe force microscopy (KPFM).
- Full Text:
- Date Issued: 2019
- Authors: Osayemwenre, Gilbert Omorodion
- Date: 2019
- Subjects: Solar cells Amorphous semiconductors Silicon
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10353/15211 , vital:40204
- Description: In this present era of sustainable energy development, photovoltaic modules which are based on amorphous silicon cells have immeasurable prospects of contributing meaningfully to the energy demand of the world at large. The global consciousness of environmental safety issues has birthed the rapid demand for the photovoltaic system. However, the production increase is mainly in bulk-type crystalline (c-Si) solar cells. Thus, to meet the high demand of the market, single junction amorphous silicon (a-Si:H) solar cells production must be encouraged through active research in that regard. This could also help to improve its efficiency and reliability. There has recently been a sharp decrease in the production cost of the bulk Si solar cell, but the a-Si:H solar cell still remains the most economically viable in comparison to the other PV technologies. Companies such as Sharp are currently developing large-scale a-Si:H solar modules that can produce an efficiency of 10.5% after the long-term degradation process. To date, a-Si:H is believed to be one of the most promising thin-film PV technologies (Saito et al., 1993; Hamakawa et al., 1994). The cost of a solar PV manufacturing fell by 6% in 2014 (Santa, 2014), this is in accordance with the 2008 cost production forecast; thus, the cost record stands at 0.20 per watt, as reported by the NPD Solar publisher. Amorphous silicon (a-Si) solar modules generate more kilowatt-hour (kWh) of electricity per kilowatt (kW) than crystalline silicon or other technologies of the same capacity of installation. Furthermore, a-Si:H modules have more functional hours per day. Single junction amorphous silicon (a-Si:H) modules can function beyond the peak sun hours, and they also have a better performance on a cloudy day. vii In other words, a 1kW PV system of a-Si:H is expected to generate more electricity per year in comparison to 1kW PV from other technologies, hence there is a low energy payback time. In this study, commercially available single junction amorphous silicon modules were bought from a local market and they were immediately deployed outdoors. The initial reading of the modules, which served as baseline reading, showed an average of 25% decrease in the modules performance, therefore, there is a need for a long term monitoring process to obtain the best and worst performing modules. Measuring the performance parameters of these PV modules under real sun light (IV) provides a better degradation assessment. This conventional assessment cannot provide an in-depth insight responsible for the variation and degradation of the performance parameters. More obscured parameters like recombination current and ideality factor were obtained from the dark IV measurements. However, this is still superficial in a way. The intrinsic parameters were obtained from scanning probe microscopy (SPM) and CV measurements. The study focuses on the degradation analysis of a-Si:H due to an increase in defect density. A rise in the defect concentration is a huge problem because it causes long-term solar cell degradation, which increases the recombination current and decreases the conversion efficiency. Furthermore, it decreases the photo-generating current and reduces the effective efficiency of the solar device. In other words, the electrical output decreases. This research investigates the reduction in a-Si:H modules’ maximum power, and correlates these with a hot spot formation. A PVPM IV tracer was used for the outdoor characterisation of the module’s temperature profile, while the IR camera was used to analyse the hot spot centre. A four probe IV/CV from NMU was used for the indoor assessment of smaller samples cleaved from both the affected and non-affected regions to characterise the electrical variations across the module viii samples. To be precise, in this study, a naturally degraded single junction amorphous silicon module was delaminated and its mechanical properties were analysed and correlated with the contact potential from a Kelvin probe force microscopy (KPFM).
- Full Text:
- Date Issued: 2019