The determination of CHARMM force field parameters for the Mg2+ containing HIV-1 integrase:
- Musyoka, Thommas M, Tastan Bishop, Özlem, Lobb, Kevin A, Moses, Vuyani
- Authors: Musyoka, Thommas M , Tastan Bishop, Özlem , Lobb, Kevin A , Moses, Vuyani
- Date: 2018
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/148139 , vital:38713 , DOI: 10.1016/j.cplett.2018.09.019
- Description: The HIV integrase enzyme is a validated drug target. However, its potential has remained largely unexploited until recently due to lack of structural and mechanistic information. Its catalytic core domain (CCD) is crucial for the viral-human DNA integration making integrase an ideal target for inhibitor design. However, in order to do so, force field parameters for the integrase magnesium ion need to be established. Quantum mechanical calculations were used to derive force field parameters which were validated through molecular dynamics studies. Our results show that the parameters determined accurately maintain the integrity of the metal pocket of the integrase CCD.
- Full Text:
- Date Issued: 2018
- Authors: Musyoka, Thommas M , Tastan Bishop, Özlem , Lobb, Kevin A , Moses, Vuyani
- Date: 2018
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/148139 , vital:38713 , DOI: 10.1016/j.cplett.2018.09.019
- Description: The HIV integrase enzyme is a validated drug target. However, its potential has remained largely unexploited until recently due to lack of structural and mechanistic information. Its catalytic core domain (CCD) is crucial for the viral-human DNA integration making integrase an ideal target for inhibitor design. However, in order to do so, force field parameters for the integrase magnesium ion need to be established. Quantum mechanical calculations were used to derive force field parameters which were validated through molecular dynamics studies. Our results show that the parameters determined accurately maintain the integrity of the metal pocket of the integrase CCD.
- Full Text:
- Date Issued: 2018
The development and implementation of a psychoeducational programme: a case study on mental toughness in a novice triathlete
- Authors: Coertzen, Marlé
- Date: 2018
- Subjects: Sports -- Psychological aspects , Triathletes -- Mental health , Toughness (Personality trait) , Triathlon -- Psychological aspects , Achievement motivation , Mental discipline , Sport Mental Toughness Questionnaire (SMTQ)
- Language: English
- Type: text , Thesis , Masters , MA
- Identifier: http://hdl.handle.net/10962/63010 , vital:28354
- Description: As an academic and applied discipline, sport psychology is interested in identifying, understanding, measuring and developing the various mental constructs that interact with physical factors, aiming to produce optimum performance and enhance athletes’ experience of sport participation. The programmes developed within sport psychology are not only applicable to sport, but have applicability within other areas, such as the performing arts, business and professions that are considered high risk, such as the military. Using a mixed methods approach and a triangulation of qualitative and quantitative data collection and analysis techniques, the goal of this research was to document the process of developing and implementing a psychoeducational mental toughness programme and to evaluate the programme through exploring the participant’s subjective experience of such a programme. The aim of the research was to contribute to the existing literature on mental toughness programmes. This was attained through administering the Sport Mental Toughness Questionnaire (SMTQ) and a semi-structured interview, which informed the development and implementation of a psychoeducational mental toughness programme relative to the idiosyncrasies of the participant and grounded in strengths-based approaches to mental toughness development. Results were obtained based on post-implementation data collected through a second administration of the SMTQ and a semi-structured interview. The participant experienced the programme as positive and results were indicative of changes in his experiences of self-confidence and control, related to the global themes of mindset, flexibility and mindfulness.
- Full Text:
- Date Issued: 2018
- Authors: Coertzen, Marlé
- Date: 2018
- Subjects: Sports -- Psychological aspects , Triathletes -- Mental health , Toughness (Personality trait) , Triathlon -- Psychological aspects , Achievement motivation , Mental discipline , Sport Mental Toughness Questionnaire (SMTQ)
- Language: English
- Type: text , Thesis , Masters , MA
- Identifier: http://hdl.handle.net/10962/63010 , vital:28354
- Description: As an academic and applied discipline, sport psychology is interested in identifying, understanding, measuring and developing the various mental constructs that interact with physical factors, aiming to produce optimum performance and enhance athletes’ experience of sport participation. The programmes developed within sport psychology are not only applicable to sport, but have applicability within other areas, such as the performing arts, business and professions that are considered high risk, such as the military. Using a mixed methods approach and a triangulation of qualitative and quantitative data collection and analysis techniques, the goal of this research was to document the process of developing and implementing a psychoeducational mental toughness programme and to evaluate the programme through exploring the participant’s subjective experience of such a programme. The aim of the research was to contribute to the existing literature on mental toughness programmes. This was attained through administering the Sport Mental Toughness Questionnaire (SMTQ) and a semi-structured interview, which informed the development and implementation of a psychoeducational mental toughness programme relative to the idiosyncrasies of the participant and grounded in strengths-based approaches to mental toughness development. Results were obtained based on post-implementation data collected through a second administration of the SMTQ and a semi-structured interview. The participant experienced the programme as positive and results were indicative of changes in his experiences of self-confidence and control, related to the global themes of mindset, flexibility and mindfulness.
- Full Text:
- Date Issued: 2018
The development of a post-settlement support framework agricultural land reform projects in South Africa
- Authors: Newborn, Ryan Oscar
- Date: 2018
- Subjects: Land reform -- South Africa , Land tenure -- South Africa Agricultural development projects -- South Africa
- Language: English
- Type: Thesis , Masters , MBA
- Identifier: http://hdl.handle.net/10948/32883 , vital:32384
- Description: After the fall of the Apartheid regime in 1994, South Africa was presented with a myriad of reform challenges that originated due to a segregational rule. Distribution of land to those who were previously disadvantaged would become and is increasingly becoming a major challenge that the African National Congress (ANC) led government would need to address. Land reform progress and performance has become a key indicator of the African National Congress’ ability to govern after more than two decades as the majority party. The African National Congress led Government of South Africa proposed a target to redistribute thirty percent of agricultural land which was owned by the white minority by the year 2014, however as of 2012, only seven percent had been redistributed with an estimated ninety percent of the farms redistributed to black farmers no longer in commercial production (Lund, 2012). Numerous factors have been attributed to land reform failure in South Africa, including but not limited to, settlement support after receiving the land. Broadly speaking, the processes leading of land reform is categorised into two fundamental categories namely; pre-settlement project fundamentals or criteria and secondly postsettlement support. The lack of or inadequate post-settlement support systems and programs is identified as a major constraint to land reform success. This research effort is aimed at gaining an understanding of what exactly the post-settlement support programs and targeted intervention are and designing an appropriate support framework that aims to reduce land reform failures and ultimately contributing to land reform success, a more inclusive rural economy and a food secure South Africa. Lumet and Qualm quote Hall in their 2012 research as saying, “Land reform has become heavy on political rhetoric and short on detail.” Whilst the ANC led government has ended the ‘willing buyer willing seller’ policy and is looking to introduce other policies to expedite land reform settlements, a significant void exists in the detail regarding post-settlement support of land reform beneficiaries to ensure success and to maintain the productivity of the reformed farms. This study aims at creating a post-settlement support framework which will add some detail as described as lacking above. Ten research questions were formulated in which the answers to the questions collectively provide insight into the post-settlement support systems required for enhanced success. The research questions are not all directly related to the post-settlement function, but also speak to other factors that need to be adequately addressed for the post-settlement function to be framed successfully. The literature review aimed at providing a backdrop to the history of land reform policies, the success and failures thereof, but more importantly it sets the scene in which an efficient post-settlement support framework must prevail. According to the interpretivist paradigm, it is assumed “that social reality is in our minds, and is subjective and multiple” (Collis & Hussey, 2009). Social reality is therefore affected by the act of investigating it. The research involves an inductive process with a view to providing an interpretive understanding of social phenomena within a particular context” (Collis & Hussey, 2009). The research effort uses an exploratory case study method. This selected method was the best approach to use to achieve the research objectives, to answer the research questions, and to test the listed propositions. The purposeful sampling unit in this study refers to land reform projects which have been in existence for five years or longer since settlement. These black emerging farmers or farmer groups are beneficiaries of the South African governments’ land reform programme and they are therefore also beneficiaries of the post-settlement support functions. Purposeful sampling involves identifying and selecting individuals or groups of individuals that are especially knowledgeable about or experienced with a phenomenon of interest while Spradley (1979) notes the importance of availability and willingness to participate, and the ability to communicate experiences and opinions in an articulate, expressive and reflective manner.
- Full Text:
- Date Issued: 2018
- Authors: Newborn, Ryan Oscar
- Date: 2018
- Subjects: Land reform -- South Africa , Land tenure -- South Africa Agricultural development projects -- South Africa
- Language: English
- Type: Thesis , Masters , MBA
- Identifier: http://hdl.handle.net/10948/32883 , vital:32384
- Description: After the fall of the Apartheid regime in 1994, South Africa was presented with a myriad of reform challenges that originated due to a segregational rule. Distribution of land to those who were previously disadvantaged would become and is increasingly becoming a major challenge that the African National Congress (ANC) led government would need to address. Land reform progress and performance has become a key indicator of the African National Congress’ ability to govern after more than two decades as the majority party. The African National Congress led Government of South Africa proposed a target to redistribute thirty percent of agricultural land which was owned by the white minority by the year 2014, however as of 2012, only seven percent had been redistributed with an estimated ninety percent of the farms redistributed to black farmers no longer in commercial production (Lund, 2012). Numerous factors have been attributed to land reform failure in South Africa, including but not limited to, settlement support after receiving the land. Broadly speaking, the processes leading of land reform is categorised into two fundamental categories namely; pre-settlement project fundamentals or criteria and secondly postsettlement support. The lack of or inadequate post-settlement support systems and programs is identified as a major constraint to land reform success. This research effort is aimed at gaining an understanding of what exactly the post-settlement support programs and targeted intervention are and designing an appropriate support framework that aims to reduce land reform failures and ultimately contributing to land reform success, a more inclusive rural economy and a food secure South Africa. Lumet and Qualm quote Hall in their 2012 research as saying, “Land reform has become heavy on political rhetoric and short on detail.” Whilst the ANC led government has ended the ‘willing buyer willing seller’ policy and is looking to introduce other policies to expedite land reform settlements, a significant void exists in the detail regarding post-settlement support of land reform beneficiaries to ensure success and to maintain the productivity of the reformed farms. This study aims at creating a post-settlement support framework which will add some detail as described as lacking above. Ten research questions were formulated in which the answers to the questions collectively provide insight into the post-settlement support systems required for enhanced success. The research questions are not all directly related to the post-settlement function, but also speak to other factors that need to be adequately addressed for the post-settlement function to be framed successfully. The literature review aimed at providing a backdrop to the history of land reform policies, the success and failures thereof, but more importantly it sets the scene in which an efficient post-settlement support framework must prevail. According to the interpretivist paradigm, it is assumed “that social reality is in our minds, and is subjective and multiple” (Collis & Hussey, 2009). Social reality is therefore affected by the act of investigating it. The research involves an inductive process with a view to providing an interpretive understanding of social phenomena within a particular context” (Collis & Hussey, 2009). The research effort uses an exploratory case study method. This selected method was the best approach to use to achieve the research objectives, to answer the research questions, and to test the listed propositions. The purposeful sampling unit in this study refers to land reform projects which have been in existence for five years or longer since settlement. These black emerging farmers or farmer groups are beneficiaries of the South African governments’ land reform programme and they are therefore also beneficiaries of the post-settlement support functions. Purposeful sampling involves identifying and selecting individuals or groups of individuals that are especially knowledgeable about or experienced with a phenomenon of interest while Spradley (1979) notes the importance of availability and willingness to participate, and the ability to communicate experiences and opinions in an articulate, expressive and reflective manner.
- Full Text:
- Date Issued: 2018
The development of a world-class operator framework for the Eastern Cape automotive component industry
- Authors: Boshoff, Waldo
- Date: 2018
- Subjects: Automobile industry and trade -- South Africa -- Eastern Cape , Lean manufacturing -- South Africa -- Eastern Cape Manufacturing processes -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Masters , MBA
- Identifier: http://hdl.handle.net/10948/21757 , vital:29760
- Description: This treatise evaluates the environment in which a world-class operator within the Eastern Cape automotive component industry is expected to work, and the skills and knowledge the operator requires to function effectively. Using both qualitative interviews and a quantitative survey four basic domains of skills and knowledge were identified: manufacturing principles, shop floor skills, shop floor knowledge and generic skills. Based on these results, a framework of required content to be included in the training and developing of a world class operator for the Eastern Cape automotive component industry is developed.
- Full Text:
- Date Issued: 2018
- Authors: Boshoff, Waldo
- Date: 2018
- Subjects: Automobile industry and trade -- South Africa -- Eastern Cape , Lean manufacturing -- South Africa -- Eastern Cape Manufacturing processes -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Masters , MBA
- Identifier: http://hdl.handle.net/10948/21757 , vital:29760
- Description: This treatise evaluates the environment in which a world-class operator within the Eastern Cape automotive component industry is expected to work, and the skills and knowledge the operator requires to function effectively. Using both qualitative interviews and a quantitative survey four basic domains of skills and knowledge were identified: manufacturing principles, shop floor skills, shop floor knowledge and generic skills. Based on these results, a framework of required content to be included in the training and developing of a world class operator for the Eastern Cape automotive component industry is developed.
- Full Text:
- Date Issued: 2018
The development of an optimised decision based methodology for the replacement timing of frontline equipment utilised within the quarrying industry
- Authors: Basson, Kenneth Mervyn
- Date: 2018
- Subjects: Decision making , Industrial equipment Industrial equipment -- Maintenance and repair
- Language: English
- Type: Thesis , Doctoral , DBA
- Identifier: http://hdl.handle.net/10948/23647 , vital:30592
- Description: At present, frontline equipment employed at B&E International, and operating within the quarrying sector is typically replaced as soon as the operating expenses are deemed to be excessive. From a capital budgeting perspective, the trigger for signalling the replacement of equipment occurs when prescribed operating cost performance metrics are violated. In some instances, a further consideration for motivating the replacement of equipment is when the perception arises that the nonavailability of the equipment employed, results in financial losses being incurred by a company. It can therefore be argued that the current equipment replacement timing methodological approach adopted at B&E International is suboptimal in nature. The situation is further aggravated by the fact that in many instances, escalation of commitment manifests itself whereby unnecessary capital is repeatedly invested in order to extend the life of an asset resulting in a situation occurring whereby the required level of investment return is not achieved. In the event of these situations arising, the decision to replace an asset is prolonged as a result of the suboptimal investment decisions being made. The primary focus of this study is to provide a methodological equipment replacement framework that is based upon sound capital budgeting fundamentals. A comprehensive literature review of capital budgeting approaches that specifically focus on the optimal replacement timing of frontline quarrying equipment, did not yield any relevant studies that have been undertaken in this regard. This study did however investigate contemporary equipment replacement approaches based upon a capital budgeting paradigm and highlighted their respective limitations. Convincing evidence obtained, indicated that the most widely accepted method of identifying the optimal replacement timing of equipment occurs when the economic life of the asset is attained. This in itself would therefore infer that a cost minimisation approach is the most pervasive methodological approach adopted in order to identify the optimal replacement timing of equipment. When considering capital investment based decisions, it was found that the discounted cash flow based methodologies are the most widely used and accepted approach applied in the mining industry. Notwithstanding this, one major caveat manifests itself in that when considering the optimal replacement timing of front line equipment within the quarrying industry, the inclusion of uncertainty, flexibility and the associated financial risks was not evident. In order to model these effects, a probabilistic Net Present Value (NPV) approach was adopted and the required Discounted Cash Flow (DCF) models were constructed. Given the uncertainty of the expected cumulative R&M profiles for the asset classes constituting this study, an extensive statistical analysis was carried out in order to establish the required predictive Repair and Maintenance (R&M) models required for the DCF analysis by means of regression analysis. Further regression analyses were conducted in order to model the overall availability and utilisation metrics for the respective asset classes included in this study. The consequence of incurring downtime was investigated and the resultant DCF analysis yielded a significant impact on the Free Cash Flow (FCF) generated by the respective assets. The magnitude of the incurred consequential financial losses incurred as a result of the respective downtime was found to be significant when considering frontline equipment. In order to model the effect of, and the extent to which, the respective independent variables influence the static NPV outcome, a sensitivity analysis was performed. From this, the influence of the independent variables constituting the NPV model employed in this study, were observed. A Real Options Analysis (ROA) approach was initially employed in order to model the effects of FCF uncertainty and the results of carrying out this analysis indicated a minimal influence on the static NPV model referred to earlier. It was therefore concluded that from an equipment replacement timing perspective, the ROA approach did not provide a robust and accurate representation of the probabilistic NPV outcomes anticipated. In order to address these perceived shortcomings, an Monte Carlo Simulation (MCS) model was constructed and the requisite probability distribution functions representing the most influential independent variables determined from the sensitivity analysis were identified and subsequently analysed. The results of the MCS analysis yielded the expected NPV outcomes that were found to be far more conservative compared to the static NPV outcomes referred to previously. Furthermore, the concluding findings of this study indicate that in order to estimate the optimal time to dispose of an asset, a static NPV analysis must first be modelled and thereafter a probabilistic NPV analysis. The respective uncertainty aspects over the lifespan of the assets should be identified to be incorporated into the MCS model. This methodological approach therefore opposes the use of a strictly deterministic based approach and rather predicates the use of a probabilistic NPV based framework. This study further concluded that traditional DCF approaches fail to consider management flexibility in terms of adapting to uncertainty and to also reduce the possibility of “escalation of commitment” occurring as a result of sub-optimal equipment replacement timing decisions by management. The use and acceptance of the traditional DCF approaches are acknowledged, but in order to develop an equipment replacement methodological approach that considers uncertainty and risk on the one hand and also allows for the incorporation of real data over the assets lifetime on the other, the use of an MCS probabilistic NPV based model was found to be the optimal approach to be adopted. The result of updating the static NPV model with updated data as soon as it is obtained enables one to generate accurate probabilistic distribution functions required for the subsequent MCS analysis. By adopting this approach the study has concluded that one can obtain realistic and accurate NPV forecasts from the anticipated FCF estimates. The principal conclusion obtained from this study is that the optimal time in which to replace front line assets employed at B&E International is when the probabilistic net earnings profile, viz., NPV of the equipment is maximized.
- Full Text:
- Date Issued: 2018
- Authors: Basson, Kenneth Mervyn
- Date: 2018
- Subjects: Decision making , Industrial equipment Industrial equipment -- Maintenance and repair
- Language: English
- Type: Thesis , Doctoral , DBA
- Identifier: http://hdl.handle.net/10948/23647 , vital:30592
- Description: At present, frontline equipment employed at B&E International, and operating within the quarrying sector is typically replaced as soon as the operating expenses are deemed to be excessive. From a capital budgeting perspective, the trigger for signalling the replacement of equipment occurs when prescribed operating cost performance metrics are violated. In some instances, a further consideration for motivating the replacement of equipment is when the perception arises that the nonavailability of the equipment employed, results in financial losses being incurred by a company. It can therefore be argued that the current equipment replacement timing methodological approach adopted at B&E International is suboptimal in nature. The situation is further aggravated by the fact that in many instances, escalation of commitment manifests itself whereby unnecessary capital is repeatedly invested in order to extend the life of an asset resulting in a situation occurring whereby the required level of investment return is not achieved. In the event of these situations arising, the decision to replace an asset is prolonged as a result of the suboptimal investment decisions being made. The primary focus of this study is to provide a methodological equipment replacement framework that is based upon sound capital budgeting fundamentals. A comprehensive literature review of capital budgeting approaches that specifically focus on the optimal replacement timing of frontline quarrying equipment, did not yield any relevant studies that have been undertaken in this regard. This study did however investigate contemporary equipment replacement approaches based upon a capital budgeting paradigm and highlighted their respective limitations. Convincing evidence obtained, indicated that the most widely accepted method of identifying the optimal replacement timing of equipment occurs when the economic life of the asset is attained. This in itself would therefore infer that a cost minimisation approach is the most pervasive methodological approach adopted in order to identify the optimal replacement timing of equipment. When considering capital investment based decisions, it was found that the discounted cash flow based methodologies are the most widely used and accepted approach applied in the mining industry. Notwithstanding this, one major caveat manifests itself in that when considering the optimal replacement timing of front line equipment within the quarrying industry, the inclusion of uncertainty, flexibility and the associated financial risks was not evident. In order to model these effects, a probabilistic Net Present Value (NPV) approach was adopted and the required Discounted Cash Flow (DCF) models were constructed. Given the uncertainty of the expected cumulative R&M profiles for the asset classes constituting this study, an extensive statistical analysis was carried out in order to establish the required predictive Repair and Maintenance (R&M) models required for the DCF analysis by means of regression analysis. Further regression analyses were conducted in order to model the overall availability and utilisation metrics for the respective asset classes included in this study. The consequence of incurring downtime was investigated and the resultant DCF analysis yielded a significant impact on the Free Cash Flow (FCF) generated by the respective assets. The magnitude of the incurred consequential financial losses incurred as a result of the respective downtime was found to be significant when considering frontline equipment. In order to model the effect of, and the extent to which, the respective independent variables influence the static NPV outcome, a sensitivity analysis was performed. From this, the influence of the independent variables constituting the NPV model employed in this study, were observed. A Real Options Analysis (ROA) approach was initially employed in order to model the effects of FCF uncertainty and the results of carrying out this analysis indicated a minimal influence on the static NPV model referred to earlier. It was therefore concluded that from an equipment replacement timing perspective, the ROA approach did not provide a robust and accurate representation of the probabilistic NPV outcomes anticipated. In order to address these perceived shortcomings, an Monte Carlo Simulation (MCS) model was constructed and the requisite probability distribution functions representing the most influential independent variables determined from the sensitivity analysis were identified and subsequently analysed. The results of the MCS analysis yielded the expected NPV outcomes that were found to be far more conservative compared to the static NPV outcomes referred to previously. Furthermore, the concluding findings of this study indicate that in order to estimate the optimal time to dispose of an asset, a static NPV analysis must first be modelled and thereafter a probabilistic NPV analysis. The respective uncertainty aspects over the lifespan of the assets should be identified to be incorporated into the MCS model. This methodological approach therefore opposes the use of a strictly deterministic based approach and rather predicates the use of a probabilistic NPV based framework. This study further concluded that traditional DCF approaches fail to consider management flexibility in terms of adapting to uncertainty and to also reduce the possibility of “escalation of commitment” occurring as a result of sub-optimal equipment replacement timing decisions by management. The use and acceptance of the traditional DCF approaches are acknowledged, but in order to develop an equipment replacement methodological approach that considers uncertainty and risk on the one hand and also allows for the incorporation of real data over the assets lifetime on the other, the use of an MCS probabilistic NPV based model was found to be the optimal approach to be adopted. The result of updating the static NPV model with updated data as soon as it is obtained enables one to generate accurate probabilistic distribution functions required for the subsequent MCS analysis. By adopting this approach the study has concluded that one can obtain realistic and accurate NPV forecasts from the anticipated FCF estimates. The principal conclusion obtained from this study is that the optimal time in which to replace front line assets employed at B&E International is when the probabilistic net earnings profile, viz., NPV of the equipment is maximized.
- Full Text:
- Date Issued: 2018
The development of armature based ceramics using South African raw materials
- Authors: Luyt, Michelle
- Date: 2018
- Subjects: Pottery -- Research -- South Africa , Pottery craft -- South Africa -- Technique Ceramics in interior decoration -- South Africa
- Language: English
- Type: Thesis , Masters , MTech
- Identifier: http://hdl.handle.net/10948/22618 , vital:30028
- Description: The purpose of the research was to develop a procedure by which South African ceramicists can use locally sourced ceramic materials to create armature based art forms, without having to rely on the importation of raw materials. The study also investigated the suitability of wire armatures as well as variable temperature ranges applicable to this investigation. It was found that commercial clay slip bodies purchased from South African suppliers tended to crack when coated over wire armatures during the firing process. It was shown that by substituting South African ceramic raw materials in the John W. Conrad’s C25 casting slip and Jeremy Dubber’s Ascent casting slip formulae with the addition of paper pulp and potassium feldspar, reduced the problem of the clay cracking when applied to wire armatures. The addition of paper fibres gave the clay bodies strong adhesive qualities which allowed the clay them to adhere onto the wire armatures which prevented the dry clay coatings from chipping off prior to and after firing. The addition of potassium feldspar helped with the maturing point of both the clay bodies and helped fuse the clay particles together which strengthened the clay coatings after being fired to their respective maturing temperatures. A further application of hydrochloric acid 30% or Pro Grip Key Coat ® to the three wire armature types, being galvanized binding wire, galvanized diamond mesh and Kanthal wire prior to coating with the above two formulae improved the adhesion of the clay slips to the armatures. This prevented them from the tendency to slide off the wire during the dipping and pouring process and helped eliminate any cracks that formed during the firing process. However, the glazing of the clay slips above proved to be problematic where it was sought as a further enhancement of the clay coated wire armatures. A general-purpose earthenware glaze caused the fired clay coating to crack probably due to the increased tension between the wire, clay body and the glaze. This problem was solved by developing a low firing transparent glaze. Other decorative effects were achieved by the inclusion of 0.5% cobalt oxide into the low firing transparent glaze which produced a blemish free deep blue colour. A further effect was achieved using binding copper wire over the bisque ware and then glazing with the low firing transparent glaze. A smoke firing technique as well an application of a copper oxide wash to the bisque fired ware and then re-firing to the required maturing temperature produced pleasing results.
- Full Text:
- Date Issued: 2018
- Authors: Luyt, Michelle
- Date: 2018
- Subjects: Pottery -- Research -- South Africa , Pottery craft -- South Africa -- Technique Ceramics in interior decoration -- South Africa
- Language: English
- Type: Thesis , Masters , MTech
- Identifier: http://hdl.handle.net/10948/22618 , vital:30028
- Description: The purpose of the research was to develop a procedure by which South African ceramicists can use locally sourced ceramic materials to create armature based art forms, without having to rely on the importation of raw materials. The study also investigated the suitability of wire armatures as well as variable temperature ranges applicable to this investigation. It was found that commercial clay slip bodies purchased from South African suppliers tended to crack when coated over wire armatures during the firing process. It was shown that by substituting South African ceramic raw materials in the John W. Conrad’s C25 casting slip and Jeremy Dubber’s Ascent casting slip formulae with the addition of paper pulp and potassium feldspar, reduced the problem of the clay cracking when applied to wire armatures. The addition of paper fibres gave the clay bodies strong adhesive qualities which allowed the clay them to adhere onto the wire armatures which prevented the dry clay coatings from chipping off prior to and after firing. The addition of potassium feldspar helped with the maturing point of both the clay bodies and helped fuse the clay particles together which strengthened the clay coatings after being fired to their respective maturing temperatures. A further application of hydrochloric acid 30% or Pro Grip Key Coat ® to the three wire armature types, being galvanized binding wire, galvanized diamond mesh and Kanthal wire prior to coating with the above two formulae improved the adhesion of the clay slips to the armatures. This prevented them from the tendency to slide off the wire during the dipping and pouring process and helped eliminate any cracks that formed during the firing process. However, the glazing of the clay slips above proved to be problematic where it was sought as a further enhancement of the clay coated wire armatures. A general-purpose earthenware glaze caused the fired clay coating to crack probably due to the increased tension between the wire, clay body and the glaze. This problem was solved by developing a low firing transparent glaze. Other decorative effects were achieved by the inclusion of 0.5% cobalt oxide into the low firing transparent glaze which produced a blemish free deep blue colour. A further effect was achieved using binding copper wire over the bisque ware and then glazing with the low firing transparent glaze. A smoke firing technique as well an application of a copper oxide wash to the bisque fired ware and then re-firing to the required maturing temperature produced pleasing results.
- Full Text:
- Date Issued: 2018
The development of natural fibre reinforced composites roof sheet
- Authors: Musikwa, Mufeba
- Date: 2018
- Subjects: Textile fibers -- Research , Textile fabrics Textile chemistry
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/32927 , vital:32398
- Description: The study aims to develop natural fibre reinforced bio-epoxy composite for use as roof sheets, manufacturing and characterization to evaluate its suitability for building applications. In this study natural fibres such as flax and kenaf were selected to reinforce bio-epoxy matrix. Different weight ratios of flax and kenaf fibres were processed by needle-punching technique to produce nonwoven mats. The nonwoven mats and bio-epoxy matrix were prepared using vacuum assisted resin transfer moulding (VARTM) at room temperature until dry and cured. The effects of weathering and water aging on the static and dynamic mechanical properties of kenaf and flax composites were investigated. Flax fibre reinforced bio-epoxy composites were found to exhibit higher tensile strength at 25% fibre content of 41.5 MPa in comparison to the composites reinforced with kenaf fibres (33.0 MPa). With regards to the drop weight impact results, flax fibre reinforced bio-epoxy composites exhibited brittle failure. Water aging results showed that kenaf fibre reinforced bio-epoxy composites absorbed less water for all fibre contents in comparison to composites reinforced with flax fibres. The tensile strength and modulus of both the composites reinforced with flax and kenaf fibres were reduced after water aging. However, the composite reinforced with kenaf fibres showed the maximum reduction in tensile strength at 25% fibre content. After UV treatment both composites reinforced with flax and kenaf fibres showed a decrease in tensile strength of 6.25% and 30%, respectively. In comparison to kenaf, bioepoxy composites reinforced with flax fibres showed an increase in tensile modulus. Both composites reinforced with flax and kenaf fibres were found to be brittle and broke easily but no colour fading was observed after UV treatment. The dynamic mechanical analyses results showed that the incorporation of flax and kenaf fibres increases the storage modulus of the composites with the maximum storage modulus value exhibited by flax fibre reinforced bio-epoxy composite at 30% fibre content. The glass transition temperature of composites reinforced with both flax and kenaf fibres shifted to lower temperatures of 79 °C and 69 °C respectively, in comparison to 96 °C for bio-epoxy resin, with the incorporation of fibres.
- Full Text:
- Date Issued: 2018
- Authors: Musikwa, Mufeba
- Date: 2018
- Subjects: Textile fibers -- Research , Textile fabrics Textile chemistry
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/32927 , vital:32398
- Description: The study aims to develop natural fibre reinforced bio-epoxy composite for use as roof sheets, manufacturing and characterization to evaluate its suitability for building applications. In this study natural fibres such as flax and kenaf were selected to reinforce bio-epoxy matrix. Different weight ratios of flax and kenaf fibres were processed by needle-punching technique to produce nonwoven mats. The nonwoven mats and bio-epoxy matrix were prepared using vacuum assisted resin transfer moulding (VARTM) at room temperature until dry and cured. The effects of weathering and water aging on the static and dynamic mechanical properties of kenaf and flax composites were investigated. Flax fibre reinforced bio-epoxy composites were found to exhibit higher tensile strength at 25% fibre content of 41.5 MPa in comparison to the composites reinforced with kenaf fibres (33.0 MPa). With regards to the drop weight impact results, flax fibre reinforced bio-epoxy composites exhibited brittle failure. Water aging results showed that kenaf fibre reinforced bio-epoxy composites absorbed less water for all fibre contents in comparison to composites reinforced with flax fibres. The tensile strength and modulus of both the composites reinforced with flax and kenaf fibres were reduced after water aging. However, the composite reinforced with kenaf fibres showed the maximum reduction in tensile strength at 25% fibre content. After UV treatment both composites reinforced with flax and kenaf fibres showed a decrease in tensile strength of 6.25% and 30%, respectively. In comparison to kenaf, bioepoxy composites reinforced with flax fibres showed an increase in tensile modulus. Both composites reinforced with flax and kenaf fibres were found to be brittle and broke easily but no colour fading was observed after UV treatment. The dynamic mechanical analyses results showed that the incorporation of flax and kenaf fibres increases the storage modulus of the composites with the maximum storage modulus value exhibited by flax fibre reinforced bio-epoxy composite at 30% fibre content. The glass transition temperature of composites reinforced with both flax and kenaf fibres shifted to lower temperatures of 79 °C and 69 °C respectively, in comparison to 96 °C for bio-epoxy resin, with the incorporation of fibres.
- Full Text:
- Date Issued: 2018
The development of rhenium(III) oxide nanoradiopharmaceuticals
- Authors: Joseph, Sinelizwi Veronica
- Date: 2018
- Subjects: Radiopharmaceuticals , Radiopharmaceuticals Rhenium
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/30507 , vital:30955
- Description: The study details the experimental work on the development of rhenium(III) oxide nanoradiopharmaceuticals for imaging and therapy of disease states. The nanoparticles (NPs) were capped with covalently linked tetraaminophthalocyanine-folate and ethylenediamine-folate to enhance their targeting ability. The capping agents were successfully synthesised and structurally characterised using Ultraviolet-Visible Spectroscopy (UV-Vis), Fourier Transform-Infrared Spectroscopy (FT-IR), Proton Nuclear Magnetic Resonance (1H-NMR), and Liquid Chromatography-Mass Spectroscopy (LC-MS). The nanoparticles were characterised using UV-Vis, spectrofluorimetry, Transmission Electron Microscopy (TEM), dynamic light scattering (DLS) and Zeta potential. Nanoparticles of sizes between 10 and 100 nm size were envisaged to be suitable for applications in biological systems. The preferred surface charge for the uptake of NPs must be between -30 and +30 mV, Re2O3 NPs capped with ethylenediamine were found to have a surface charge of -49 mV as compared with NPs capped with ethylenediamine-folate which gave -18.6 mV. The cytotoxicity studies of the nanoparticles were tested against four different cell lines: MDA-MB-468, MDA-MB-231, MCF-7, and MCF-10A. The cell survival rate after treatment was done with different capped rhenium(III) oxide nanoparticles obtained at a 10 μM concentration showed more than 80% cell viability. A comparison was conducted based on different nanoparticle sizes of capping agents across the four cell lines of varying folate receptor. All the cell lines were compared, and it was observed that MCF-7 had high percentage of cell viability especially with the cells treated with folate conjugated nanoparticles. Further investigation was done on the effects of folate conjugates and the effects of size. It was observed that the tetraaminophthalocyanine-folate favoured the MCF-7, for large-sized nanoparticles. However, further work is required to test the cancer cell internalisation of the nanoparticles using TEM as well as the correct size for endocytosis. Thereafter, the mice model study will be carried out for investigation of biodistribution of particles in tumour tissue using hot isotopes (186/188Re) and this will be done in a radiophamarceutical laboratory.
- Full Text:
- Date Issued: 2018
- Authors: Joseph, Sinelizwi Veronica
- Date: 2018
- Subjects: Radiopharmaceuticals , Radiopharmaceuticals Rhenium
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/30507 , vital:30955
- Description: The study details the experimental work on the development of rhenium(III) oxide nanoradiopharmaceuticals for imaging and therapy of disease states. The nanoparticles (NPs) were capped with covalently linked tetraaminophthalocyanine-folate and ethylenediamine-folate to enhance their targeting ability. The capping agents were successfully synthesised and structurally characterised using Ultraviolet-Visible Spectroscopy (UV-Vis), Fourier Transform-Infrared Spectroscopy (FT-IR), Proton Nuclear Magnetic Resonance (1H-NMR), and Liquid Chromatography-Mass Spectroscopy (LC-MS). The nanoparticles were characterised using UV-Vis, spectrofluorimetry, Transmission Electron Microscopy (TEM), dynamic light scattering (DLS) and Zeta potential. Nanoparticles of sizes between 10 and 100 nm size were envisaged to be suitable for applications in biological systems. The preferred surface charge for the uptake of NPs must be between -30 and +30 mV, Re2O3 NPs capped with ethylenediamine were found to have a surface charge of -49 mV as compared with NPs capped with ethylenediamine-folate which gave -18.6 mV. The cytotoxicity studies of the nanoparticles were tested against four different cell lines: MDA-MB-468, MDA-MB-231, MCF-7, and MCF-10A. The cell survival rate after treatment was done with different capped rhenium(III) oxide nanoparticles obtained at a 10 μM concentration showed more than 80% cell viability. A comparison was conducted based on different nanoparticle sizes of capping agents across the four cell lines of varying folate receptor. All the cell lines were compared, and it was observed that MCF-7 had high percentage of cell viability especially with the cells treated with folate conjugated nanoparticles. Further investigation was done on the effects of folate conjugates and the effects of size. It was observed that the tetraaminophthalocyanine-folate favoured the MCF-7, for large-sized nanoparticles. However, further work is required to test the cancer cell internalisation of the nanoparticles using TEM as well as the correct size for endocytosis. Thereafter, the mice model study will be carried out for investigation of biodistribution of particles in tumour tissue using hot isotopes (186/188Re) and this will be done in a radiophamarceutical laboratory.
- Full Text:
- Date Issued: 2018
The development, manufacture and assessment of solid dispersions of gliclazide
- Authors: Govere, Grace Shalom
- Date: 2018
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/63390 , vital:28405
- Description: Expected release date-April 2020
- Full Text:
- Date Issued: 2018
- Authors: Govere, Grace Shalom
- Date: 2018
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/63390 , vital:28405
- Description: Expected release date-April 2020
- Full Text:
- Date Issued: 2018
The development, manufacture and evaluation of a selfmicro-emulsifying drug delivery system for efavirenz
- Musakana, Tanyaradzwa Gracious
- Authors: Musakana, Tanyaradzwa Gracious
- Date: 2018
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/62643 , vital:28223
- Description: Expected release date-April 2020
- Full Text:
- Date Issued: 2018
- Authors: Musakana, Tanyaradzwa Gracious
- Date: 2018
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/62643 , vital:28223
- Description: Expected release date-April 2020
- Full Text:
- Date Issued: 2018
The development, manufacture and evaluation of sustained release gastric-resistant isoniazid and gastroretentive microporous rifampicin microspheres
- Authors: Mwila, Chiluba
- Date: 2018
- Subjects: Biodegradation , Microspheres (Pharmacy) , Drug delivery systems , Rifampin , Isoniazid
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/63497 , vital:28421 , DOI 10.21504/10962/63497
- Description: According to the World Health Organization Global Tuberculosis (TB) 2017 Report, there were an estimated 10.4 million new TB cases worldwide of which, in 2016, 65 % occurred in men, 28.1 % in women and 6.9 % in children. TB is the ninth leading cause of death globally and is the leading cause due to an infectious organism surpassing HIV/AIDS. Treatment is long-term and the use of a combination of medicines is required for success. The concern related to the use of fixed dose combination products for the treatment of TB is the issue of low bioavailability of rifampicin observed from a number of fixed dose combination (FDC) formulations. The hydrolysis of rifampicin, in acidic media, to form insoluble 3-formyl rifamycin SV contributes to poor bioavailability of rifampicin. The degradation of rifampicin to form this poorly absorbed compound is accelerated in the presence of isoniazid via the reversible formation of isonicotinyl hydrazone is a further factor contributing to the poor bioavailability of rifampicin. Therefore, the development of a novel drug delivery technology that prevents interactions between rifampicin and isoniazid in an acidic medium is required. A Box Behnken design was successfully used for the optimisation of a rapid and accurate stability-indicating gradient elution RP-HPLC method for the simultaneous analysis of isoniazid, pyrazinamide and rifampicin. The method was validated using ICH guidelines and the results indicate it can be used for the rapid analysis of commercially available TB FDC formulations containing the active pharmaceutical ingredients, API. The method is precise, sensitive and has the necessary selectivity for use during formulation development and optimisation studies for a combination of rifampicin, isoniazid and pyrazinamide. Initially formulation activities were undertaken with rifampicin and isoniazid for the development of an approach to enhance the effective delivery of these compounds. The characterisation of rifampicin and isoniazid was undertaken using spectroscopic, thermal and microscopic analysis. The studies revealed that the compounds are crystalline and exhibit distinct characteristic sharp peaks in X-ray diffractograms and Differential Scanning Calorimetry thermograms. The thermograms, 13C Nuclear Magnetic Resonance and Fourier Transform Infrared spectroscopy results identified that rifampicin occurs as the form II polymorph however, as there are no significant biopharmaceutic differences between the polymorphic forms of rifampicin this information was used for identification purposes only. The results were used as baseline data for comparative purposes to monitor changes that may occur when rifampicin and isoniazid are used in formulation development, dosage form manufacture and characterisation activities for a FDC technology designed to deliver both compounds simultaneously. Hydroxypropylmethylcellulose acetate succinate (HPMC-AS) and Eudragit® L100 polymers were successfully used for manufacture of isoniazid loaded gastric-resistant sustained release microspheres using an o/o solvent emulsification and evaporation approach. A Hybrid experimental design was used to investigate the influence of input variables viz., homogenisation speed and amount of HPMC-AS and Eudragit® L100 on gastric-resistance, INH release and encapsulation efficiency. The approach of using coating polymers viz., HPMC-AS and Eudragit® L100, to manufacture gastric resistant sustained release microspheres of isoniazid is unique and was efficient for preventing the release of isoniazid in an acidic environment. Only 0.523 % isoniazid was released from the optimised formulation after 2 h exposure to pH 1.2 0.1 M HCl suggesting there is also the possibility of minimising the accelerated degradation of rifampicin that occurs in the presence of isoniazid in acidic media. The microspheres also exhibited sustained release properties without burst release in pH 6.8 0.1 M phosphate buffer as < 5 % isoniazid was released at 0.5 h and only 11 % isoniazid was released at 2 h. The release of isoniazid was sustained over the entire period of dissolution testing with > 85 % isoniazid released at 24 h, implying that the majority of encapsulated isoniazid would be available for absorption. The manufacturing process resulted in the production of hard spherical particles and particle size analysis revealed that the microspheres ranged between 415.76 ± 76.93 μm and 903.35 ± 197.10 μm in diameter. The microspheres exhibited excellent flow properties attributed to the spherical nature of particles. Carr‟s index (CI) was 4.934 ± 0.775 % and the Hausner ratio (HR) was 1.148 ± 0.033 indicating good packability of the microspheres that would help in achieving weight and content uniformity of capsule dosage units. The manufacturing process however produced a low % yield suggesting that scale up difficulties may be encountered. However the high encapsulation efficiency observed may counter the challenges associated with the low yield. The DSC thermograms and FT Raman spectra of 1:1 mixtures of isoniazid, excipients and the microspheres did not reveal any potential detrimental interactions. Microporous floating sustained release microspheres for the delivery of rifampicin in the stomach have been successfully manufactured using emulsification and a diffusion/evaporation process. A novel approach using solvent mixture of acetone and dichloromethane that has not been reported for the manufacture of rifampicin microspheres was successfully used and resulted in the formation of a stable emulsion and the manufacture of rifampicin-loaded microspheres with uniform characteristics. In addition the manufacturing process was shorter than most other reported methods. A Box-Behnken experimental design was successfully used to study the influence of ethylcellulose, Eudragit® RLPO and d-glucose content on the floating properties, encapsulation efficiency and % yield of microspheres. The optimised formulation did not yield desired floating characteristics as the % buoyancy was low and floating lag times were high. The optimised formulation was modified by addition of NaHCO3 to increase the % buoyancy and reduce the floating lag time. Rifampicin release from the microspheres of the modified batch was 87.10 % at 12 h and the microspheres exhibited a % buoyancy of 87.66 ± 1.28 % (n = 6) and floating lag time of 15 ± 3.2 (n = 6) seconds. The microspheres remained buoyant for up to 12 h and an encapsulation efficiency of 88.26 ± 1.25 % was achieved. SEM images of microspheres following exposure to dissolution fluid revealed that the microspheres had numerous pores on their surface. The mean particle size distribution ranged between 423.19 ± 121.86 μm to 620.07 ± 102.67 μm. The microspheres exhibited similar flow characteristics to isoniazid microspheres with a CI of 1.422 ± 0.074 %, and HR of 1.034 ± 0.002. The excellent flow characteristics indicate that filling of the microspheres into hard gelatin capsules was unlikely to pose a challenge in respect of producing a product with uniform content. Rifampicin-excipient compatibility studies did not reveal any potential or significant interactions suggesting that the excipients used for the manufacture of the microspheres were compatible, although long term stability studies would be required to ascertain this is, indeed the case. The microporous floating sustained release microspheres manufactured in these studies has the potential to increase the bioavailability of rifampicin as they may be retained in the stomach where the solubility of rifampicin is high and from which absorption is best achieved. The degradation of rifampicin after 12 h dissolution testing in pH 1.2 0.1 M HCl in the presence of isoniazid gastric-resistant sustained release microspheres was only 4.44%. These results indicate that the degradation of rifampicin in the presence of isoniazid in acidic media can be overcome by encapsulation of both active pharmaceutical ingredients in a manner that ensure release in different segments of the gastrointestinal tract. The use of sustained release microporous gastroretentive rifampicin microspheres in combination with sustained release isoniazid gastric-resistant microspheres revealed that accelerated degradation of rifampicin in the presence of isoniazid is reduced significantly when using this approach and a FDC of rifampicin and isoniazid microspheres has the potential to improve the bioavailability of rifampicin thereby enhancing therapeutic outcomes. In vivo studies would be required to confirm the potential benefits of using this approach to deliver rifampicin in combination with isoniazid. , Thesis (PhD) -- Faculty of Pharmacy, Pharmacy, 2018
- Full Text:
- Date Issued: 2018
- Authors: Mwila, Chiluba
- Date: 2018
- Subjects: Biodegradation , Microspheres (Pharmacy) , Drug delivery systems , Rifampin , Isoniazid
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/63497 , vital:28421 , DOI 10.21504/10962/63497
- Description: According to the World Health Organization Global Tuberculosis (TB) 2017 Report, there were an estimated 10.4 million new TB cases worldwide of which, in 2016, 65 % occurred in men, 28.1 % in women and 6.9 % in children. TB is the ninth leading cause of death globally and is the leading cause due to an infectious organism surpassing HIV/AIDS. Treatment is long-term and the use of a combination of medicines is required for success. The concern related to the use of fixed dose combination products for the treatment of TB is the issue of low bioavailability of rifampicin observed from a number of fixed dose combination (FDC) formulations. The hydrolysis of rifampicin, in acidic media, to form insoluble 3-formyl rifamycin SV contributes to poor bioavailability of rifampicin. The degradation of rifampicin to form this poorly absorbed compound is accelerated in the presence of isoniazid via the reversible formation of isonicotinyl hydrazone is a further factor contributing to the poor bioavailability of rifampicin. Therefore, the development of a novel drug delivery technology that prevents interactions between rifampicin and isoniazid in an acidic medium is required. A Box Behnken design was successfully used for the optimisation of a rapid and accurate stability-indicating gradient elution RP-HPLC method for the simultaneous analysis of isoniazid, pyrazinamide and rifampicin. The method was validated using ICH guidelines and the results indicate it can be used for the rapid analysis of commercially available TB FDC formulations containing the active pharmaceutical ingredients, API. The method is precise, sensitive and has the necessary selectivity for use during formulation development and optimisation studies for a combination of rifampicin, isoniazid and pyrazinamide. Initially formulation activities were undertaken with rifampicin and isoniazid for the development of an approach to enhance the effective delivery of these compounds. The characterisation of rifampicin and isoniazid was undertaken using spectroscopic, thermal and microscopic analysis. The studies revealed that the compounds are crystalline and exhibit distinct characteristic sharp peaks in X-ray diffractograms and Differential Scanning Calorimetry thermograms. The thermograms, 13C Nuclear Magnetic Resonance and Fourier Transform Infrared spectroscopy results identified that rifampicin occurs as the form II polymorph however, as there are no significant biopharmaceutic differences between the polymorphic forms of rifampicin this information was used for identification purposes only. The results were used as baseline data for comparative purposes to monitor changes that may occur when rifampicin and isoniazid are used in formulation development, dosage form manufacture and characterisation activities for a FDC technology designed to deliver both compounds simultaneously. Hydroxypropylmethylcellulose acetate succinate (HPMC-AS) and Eudragit® L100 polymers were successfully used for manufacture of isoniazid loaded gastric-resistant sustained release microspheres using an o/o solvent emulsification and evaporation approach. A Hybrid experimental design was used to investigate the influence of input variables viz., homogenisation speed and amount of HPMC-AS and Eudragit® L100 on gastric-resistance, INH release and encapsulation efficiency. The approach of using coating polymers viz., HPMC-AS and Eudragit® L100, to manufacture gastric resistant sustained release microspheres of isoniazid is unique and was efficient for preventing the release of isoniazid in an acidic environment. Only 0.523 % isoniazid was released from the optimised formulation after 2 h exposure to pH 1.2 0.1 M HCl suggesting there is also the possibility of minimising the accelerated degradation of rifampicin that occurs in the presence of isoniazid in acidic media. The microspheres also exhibited sustained release properties without burst release in pH 6.8 0.1 M phosphate buffer as < 5 % isoniazid was released at 0.5 h and only 11 % isoniazid was released at 2 h. The release of isoniazid was sustained over the entire period of dissolution testing with > 85 % isoniazid released at 24 h, implying that the majority of encapsulated isoniazid would be available for absorption. The manufacturing process resulted in the production of hard spherical particles and particle size analysis revealed that the microspheres ranged between 415.76 ± 76.93 μm and 903.35 ± 197.10 μm in diameter. The microspheres exhibited excellent flow properties attributed to the spherical nature of particles. Carr‟s index (CI) was 4.934 ± 0.775 % and the Hausner ratio (HR) was 1.148 ± 0.033 indicating good packability of the microspheres that would help in achieving weight and content uniformity of capsule dosage units. The manufacturing process however produced a low % yield suggesting that scale up difficulties may be encountered. However the high encapsulation efficiency observed may counter the challenges associated with the low yield. The DSC thermograms and FT Raman spectra of 1:1 mixtures of isoniazid, excipients and the microspheres did not reveal any potential detrimental interactions. Microporous floating sustained release microspheres for the delivery of rifampicin in the stomach have been successfully manufactured using emulsification and a diffusion/evaporation process. A novel approach using solvent mixture of acetone and dichloromethane that has not been reported for the manufacture of rifampicin microspheres was successfully used and resulted in the formation of a stable emulsion and the manufacture of rifampicin-loaded microspheres with uniform characteristics. In addition the manufacturing process was shorter than most other reported methods. A Box-Behnken experimental design was successfully used to study the influence of ethylcellulose, Eudragit® RLPO and d-glucose content on the floating properties, encapsulation efficiency and % yield of microspheres. The optimised formulation did not yield desired floating characteristics as the % buoyancy was low and floating lag times were high. The optimised formulation was modified by addition of NaHCO3 to increase the % buoyancy and reduce the floating lag time. Rifampicin release from the microspheres of the modified batch was 87.10 % at 12 h and the microspheres exhibited a % buoyancy of 87.66 ± 1.28 % (n = 6) and floating lag time of 15 ± 3.2 (n = 6) seconds. The microspheres remained buoyant for up to 12 h and an encapsulation efficiency of 88.26 ± 1.25 % was achieved. SEM images of microspheres following exposure to dissolution fluid revealed that the microspheres had numerous pores on their surface. The mean particle size distribution ranged between 423.19 ± 121.86 μm to 620.07 ± 102.67 μm. The microspheres exhibited similar flow characteristics to isoniazid microspheres with a CI of 1.422 ± 0.074 %, and HR of 1.034 ± 0.002. The excellent flow characteristics indicate that filling of the microspheres into hard gelatin capsules was unlikely to pose a challenge in respect of producing a product with uniform content. Rifampicin-excipient compatibility studies did not reveal any potential or significant interactions suggesting that the excipients used for the manufacture of the microspheres were compatible, although long term stability studies would be required to ascertain this is, indeed the case. The microporous floating sustained release microspheres manufactured in these studies has the potential to increase the bioavailability of rifampicin as they may be retained in the stomach where the solubility of rifampicin is high and from which absorption is best achieved. The degradation of rifampicin after 12 h dissolution testing in pH 1.2 0.1 M HCl in the presence of isoniazid gastric-resistant sustained release microspheres was only 4.44%. These results indicate that the degradation of rifampicin in the presence of isoniazid in acidic media can be overcome by encapsulation of both active pharmaceutical ingredients in a manner that ensure release in different segments of the gastrointestinal tract. The use of sustained release microporous gastroretentive rifampicin microspheres in combination with sustained release isoniazid gastric-resistant microspheres revealed that accelerated degradation of rifampicin in the presence of isoniazid is reduced significantly when using this approach and a FDC of rifampicin and isoniazid microspheres has the potential to improve the bioavailability of rifampicin thereby enhancing therapeutic outcomes. In vivo studies would be required to confirm the potential benefits of using this approach to deliver rifampicin in combination with isoniazid. , Thesis (PhD) -- Faculty of Pharmacy, Pharmacy, 2018
- Full Text:
- Date Issued: 2018
The distribution and abundance of the stem-galling fly, Cecidochares connexa (Macquart)(Diptera: Tephritidae), a biological control agent of Chromolaena odorata (L.)(Asteraceae), in Ghana
- Aigbedion-Atalor, Pascal O, Wilson, David D, Eziah, Vincent Y, Day, Michael D, Paterson, Iain D
- Authors: Aigbedion-Atalor, Pascal O , Wilson, David D , Eziah, Vincent Y , Day, Michael D , Paterson, Iain D
- Date: 2018
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/407074 , vital:70334 , xlink:href="https://hdl.handle.net/10520/EJC-113112d1da"
- Description: Chromolaena odorata (L.) R.M. King and H. Robinson (Asteraceae: Eupatorieae) is one of the worst invasive weeds in West Africa, and a serious biotic threat to food security. The stem-galling fly, Cecidochares connexa (Macquart) (Diptera: Tephritidae), a biological control agent for C. odorata, was released in the Ivory Coast in 2003 and first detected in Ghana in 2014. The spatiotemporal distribution and abundance of C. connexa in Ghana was determined by country-wide surveys from 2015 to 2016. Galls were found in varying densities across Ghana but gall densities were consistently low east of Lake Volta. A limited survey conducted in the extreme west of Togo in 2016, found the gall fly also in low numbers. There was a significant correlation between C. connexa gall densities and the distance from the release sites in the Ivory Coast. The distribution and abundance of the gall fly in Ghana could be explained by its spread from the original release sites over time and/or the much drier conditions east of Lake Volta. Cecidochares connexa has dispersed a distance of about 1000 km over a 10-year period and, while there is some evidence that the gall fly is still dispersing towards the east, its range and population size could be limited by the dry climatic conditions in the east of Ghana and in Togo. Actively redistributing the agent over this dry corridor to the more humid and higher rainfall areas of Nigeria, may result in the spread of this agent through the rest of West and Central Africa, thereby aiding the control of C. odorata in the region.
- Full Text:
- Date Issued: 2018
- Authors: Aigbedion-Atalor, Pascal O , Wilson, David D , Eziah, Vincent Y , Day, Michael D , Paterson, Iain D
- Date: 2018
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/407074 , vital:70334 , xlink:href="https://hdl.handle.net/10520/EJC-113112d1da"
- Description: Chromolaena odorata (L.) R.M. King and H. Robinson (Asteraceae: Eupatorieae) is one of the worst invasive weeds in West Africa, and a serious biotic threat to food security. The stem-galling fly, Cecidochares connexa (Macquart) (Diptera: Tephritidae), a biological control agent for C. odorata, was released in the Ivory Coast in 2003 and first detected in Ghana in 2014. The spatiotemporal distribution and abundance of C. connexa in Ghana was determined by country-wide surveys from 2015 to 2016. Galls were found in varying densities across Ghana but gall densities were consistently low east of Lake Volta. A limited survey conducted in the extreme west of Togo in 2016, found the gall fly also in low numbers. There was a significant correlation between C. connexa gall densities and the distance from the release sites in the Ivory Coast. The distribution and abundance of the gall fly in Ghana could be explained by its spread from the original release sites over time and/or the much drier conditions east of Lake Volta. Cecidochares connexa has dispersed a distance of about 1000 km over a 10-year period and, while there is some evidence that the gall fly is still dispersing towards the east, its range and population size could be limited by the dry climatic conditions in the east of Ghana and in Togo. Actively redistributing the agent over this dry corridor to the more humid and higher rainfall areas of Nigeria, may result in the spread of this agent through the rest of West and Central Africa, thereby aiding the control of C. odorata in the region.
- Full Text:
- Date Issued: 2018
The ecological risk of acid mine drainage in a salinising landscape
- Authors: Vellemu, Emmanuel Captain
- Date: 2018
- Subjects: Acid mine drainage Environmental aspects South Africa Mpumalanga , Salinization South Africa Mpumalanga , Water salinization South Africa Mpumalanga , Water quality South Africa Mpumalanga , Aquatic animals Effect of water quality on South Africa Mpumalanga , Freshwater ecology South Africa Mpumalanga
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/60563 , vital:27797
- Description: Acid mine drainage (AMD) and increasing salinity of freshwater ecosystems pose serious threats to water quality in water-stressed South Africa. These threats are exacerbated by mining activities, mainly gold and coal from both active and abandoned mines that continue to release acidic water that is rich in toxic metals and high sulphate concentrations. Therefore, the overarching hypothesis for this study was that “the combination of AMD and sulphate salts confers high ecological risk to the aquatic biota”. The study employed both laboratory and field investigations to test this hypothesis and provide appropriate tools to protect freshwater ecosystems from increasing anthropogenic impacts. Firstly, a laboratory investigation was carried out to develop risk-based water quality guidelines (WQGs) for sulphates and treated AMD (TAMD) using the species sensitivity distributions (SSDs) technique. Five South African freshwater species belonging to five different taxonomic groupings, including Adenophlebia auriculata (insect), Burnupia stenochorias (mollusc), Caridina nilotica (crustacea), Pseudokirchneriella subcapitata (algae) and Oreochromis mossambicus (fish) were exposed to varying concentrations of sodium sulphate (Na2SO4), magnesium sulphate (MgSO4) and calcium sulphate (CaSO4), as well as TAMD in separate ecotoxicological experiments, applying short-term (96 h) non-renewal and long-term (240 h) renewal exposure test methods. Secondly, a novel trait-based approach (TBA) was also used to predict the vulnerability of taxa to treated acid mine drainage (TAMD). The TBA used a combination of carefully selected traits of organisms that are mechanistically linked to TAMD for their potential vulnerability predictions. Leptoceridae (caddisflies) and Leptophlebiidae (mayflies) were selected taxa for evaluation of the trait-based vulnerability predictions to TAMD for laboratory toxicity exposures. This was followed by a field investigation to assess macroinvertebrates assemblage responses, abundance and richness to a TAMD-impacted stream using the South African Scoring System version 5 (SASS5) protocol. Outcomes form the above three sources were combined in a multi-criteria analysis (MCA) to develop an appropriate water quality management strategy in a form of a trait-based decision-making support tool. Results of the risk-based WQGs revealed that Na2SO4 was the most toxic of the tested salts. A concentration of 0.020 g/L Na2SO4, 0.055 g/L CaSO4, and 0.108 g/L MgSO4 or a combined sulphate salts limit of 0.067 g/L were derived as long-term WQGs to protect over 95% of the population species in a natural environment considered as relatively pristine. This means that the generic 0.25 g/L sulphate compliance limit for South African freshwater systems is under-protective. Burnupia stenochorias was the most sensitive to AMD after long-term exposures, and it was adjudged as a good indicator of AMD along with P. subcapitata. Long-term scenario-specific WQG for AMD for the protection of over 95% of the population species was derived as 0.014%. Results of the TBA revealed that the relative abundance and diversity of taxa at a site that received direct impact from TAMD generally corresponded to trait-based predictions. The site that received direct TAMD was largely dominated by members of the Corixidae and Naucoridae families. However, Leptoceridae was more vulnerable to TAMD than Leptophlebidae contrary to predictions. Its assemblage did not match the predictions although Leptophlebiidae corresponded to predictions in terms of its assemblage and diversity. As water quality improved further downstream of the TAMD source, macroinvertebrates assemblage and diversity also improved as predicted. However, it is important to note that other equally important traits that were not studied might influence the response of organisms during toxicity test exposures. The MCA findings suggest that the trait-based decision-making support tool is a useful management strategy for the predicting vulnerability of taxa aquatic stressors including AMD and increasing salinity. Overall, the outcome of this study suggests that AMD poses an ecological risk to aquatic biota, but this becomes riskier in the presence of excess sulphate salts. Albeit, the WQGs for sulphate salts and AMD as well as the developed trait-based decision support tool all contribute novel sound scientific knowledge basis for managing the AMD and increasing salinity in freshwater ecosystems. The study recommends incorporating different life stages of indigenous species tested to determine if their sensitivity to AMD and sulphate would correspond to current findings because early life stages could be more sensitive to aquatic stressors than juveniles or adults. This is important for the derivation of strong and relevant WQGs. The TBA requires further refinement for its incorporation in ecotoxicology on a wide scale.
- Full Text:
- Date Issued: 2018
- Authors: Vellemu, Emmanuel Captain
- Date: 2018
- Subjects: Acid mine drainage Environmental aspects South Africa Mpumalanga , Salinization South Africa Mpumalanga , Water salinization South Africa Mpumalanga , Water quality South Africa Mpumalanga , Aquatic animals Effect of water quality on South Africa Mpumalanga , Freshwater ecology South Africa Mpumalanga
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/60563 , vital:27797
- Description: Acid mine drainage (AMD) and increasing salinity of freshwater ecosystems pose serious threats to water quality in water-stressed South Africa. These threats are exacerbated by mining activities, mainly gold and coal from both active and abandoned mines that continue to release acidic water that is rich in toxic metals and high sulphate concentrations. Therefore, the overarching hypothesis for this study was that “the combination of AMD and sulphate salts confers high ecological risk to the aquatic biota”. The study employed both laboratory and field investigations to test this hypothesis and provide appropriate tools to protect freshwater ecosystems from increasing anthropogenic impacts. Firstly, a laboratory investigation was carried out to develop risk-based water quality guidelines (WQGs) for sulphates and treated AMD (TAMD) using the species sensitivity distributions (SSDs) technique. Five South African freshwater species belonging to five different taxonomic groupings, including Adenophlebia auriculata (insect), Burnupia stenochorias (mollusc), Caridina nilotica (crustacea), Pseudokirchneriella subcapitata (algae) and Oreochromis mossambicus (fish) were exposed to varying concentrations of sodium sulphate (Na2SO4), magnesium sulphate (MgSO4) and calcium sulphate (CaSO4), as well as TAMD in separate ecotoxicological experiments, applying short-term (96 h) non-renewal and long-term (240 h) renewal exposure test methods. Secondly, a novel trait-based approach (TBA) was also used to predict the vulnerability of taxa to treated acid mine drainage (TAMD). The TBA used a combination of carefully selected traits of organisms that are mechanistically linked to TAMD for their potential vulnerability predictions. Leptoceridae (caddisflies) and Leptophlebiidae (mayflies) were selected taxa for evaluation of the trait-based vulnerability predictions to TAMD for laboratory toxicity exposures. This was followed by a field investigation to assess macroinvertebrates assemblage responses, abundance and richness to a TAMD-impacted stream using the South African Scoring System version 5 (SASS5) protocol. Outcomes form the above three sources were combined in a multi-criteria analysis (MCA) to develop an appropriate water quality management strategy in a form of a trait-based decision-making support tool. Results of the risk-based WQGs revealed that Na2SO4 was the most toxic of the tested salts. A concentration of 0.020 g/L Na2SO4, 0.055 g/L CaSO4, and 0.108 g/L MgSO4 or a combined sulphate salts limit of 0.067 g/L were derived as long-term WQGs to protect over 95% of the population species in a natural environment considered as relatively pristine. This means that the generic 0.25 g/L sulphate compliance limit for South African freshwater systems is under-protective. Burnupia stenochorias was the most sensitive to AMD after long-term exposures, and it was adjudged as a good indicator of AMD along with P. subcapitata. Long-term scenario-specific WQG for AMD for the protection of over 95% of the population species was derived as 0.014%. Results of the TBA revealed that the relative abundance and diversity of taxa at a site that received direct impact from TAMD generally corresponded to trait-based predictions. The site that received direct TAMD was largely dominated by members of the Corixidae and Naucoridae families. However, Leptoceridae was more vulnerable to TAMD than Leptophlebidae contrary to predictions. Its assemblage did not match the predictions although Leptophlebiidae corresponded to predictions in terms of its assemblage and diversity. As water quality improved further downstream of the TAMD source, macroinvertebrates assemblage and diversity also improved as predicted. However, it is important to note that other equally important traits that were not studied might influence the response of organisms during toxicity test exposures. The MCA findings suggest that the trait-based decision-making support tool is a useful management strategy for the predicting vulnerability of taxa aquatic stressors including AMD and increasing salinity. Overall, the outcome of this study suggests that AMD poses an ecological risk to aquatic biota, but this becomes riskier in the presence of excess sulphate salts. Albeit, the WQGs for sulphate salts and AMD as well as the developed trait-based decision support tool all contribute novel sound scientific knowledge basis for managing the AMD and increasing salinity in freshwater ecosystems. The study recommends incorporating different life stages of indigenous species tested to determine if their sensitivity to AMD and sulphate would correspond to current findings because early life stages could be more sensitive to aquatic stressors than juveniles or adults. This is important for the derivation of strong and relevant WQGs. The TBA requires further refinement for its incorporation in ecotoxicology on a wide scale.
- Full Text:
- Date Issued: 2018
The economic and ecological trade-offs of wetland conversion for development projects: the case of the Kampala–Mukono corridor
- Authors: Wasswa, Hannington
- Date: 2018
- Subjects: Wetland ecology -- Uganda -- Kampala , Wetlands -- Uganda -- Kampala Wetland management -- Uganda -- Kampala Hydrogeology
- Language: English
- Type: Thesis , Doctoral , DPhil
- Identifier: http://hdl.handle.net/10948/36409 , vital:33939
- Description: Wetland diminution for development projects (DPs) in the Kampala–Mukono Corridor (KMC) continues to pose threats to the socio-economic and ecological benefits of wetlands because decision-makers and wetland users at various levels often have insufficient knowledge of these benefits. This situation has resulted in unsustainable development decisions that accord little weight to wetlands and have allocated many of them to DPs. In order to inform decision making for optimal development in the KMC, the present study analysed the spatial and temporal wetland loss to DPs, estimated the economic value of the KMC wetlands, and assessed the environmental consequences of wetland conversion for DPs. Sets of ortho-rectified and cloud-free multi-temporal Landsat MSS (1974) and Landsat TM/ETM+ images (30m) for 1986, 2006, and 2013 were analysed in a spatial and temporal framework. The 79m Landsat image (MSS) of 1974 was resampled and later filtered with subsequent 30m images using a majority filter method. An unsupervised classification approach was employed to characterize the wetlands and associated DPs. The classified DPs and wetland cover types were validated by reference to topographical maps (sheets) of 1974 at a scale of 1:50,000 obtained from Uganda Lands and Surveys, apriori knowledge and Google earth images corresponding to the same spatial and temporal frames. The IDRISI Selva-based Markov Chain model was employed to model future wetland loss to DPs. The Total Economic Valuation Approach (TEV) was employed to quantify selected use values of wetland economic benefits using the market price, replacement cost and contingent valuation techniques. The ecological implications of wetland loss focused on soil organic carbon (SOC) and hydrological impacts in the KMC wetlands. The estimated SOC was assessed with climatic data in order to infer the implication of SOC loss for local climate variability. The manual wet chemistry/oxidation method by Walkley-Black (1934) was adopted to estimate SOC in various wetland cover types. Hydrological impact assessments focused on water quality analysis in various wetland cover types, with major parameters being total nitrogen (TN), total phosphorous (TP) total dissolved solids – (TDS) and total suspended sediments (TSS). Hydrologic flow data parameters across the different wetland cover types in the KMC focused on water level, speed, stream width, and bed load. Results from analysis of the spatial-temporal wetland change revealed that by 2013 the KMC wetlands had lost almost half (47%) of their 1974 areal coverage, with 56% of this loss resulting from conversion to DPs. It is projected that 26% of the KMC wetlands will be lost to more DPs by 2040. Wetland loss is attributed to intensified economic activity and preference of Kampala as an industrial zone, weakness in the previous spatial planning of Kampala, and the general lack of information flow to various institutions involved in the establishment of DPs. The KMC wetlands provide a flow of economic benefits at a minimum approximated value of US$ 3,418 / ha / per year. It is revealed that a great deal of these economic benefits (88%) accrues to the local subsistence level in the form of livelihood products, incomes, and employment benefits. The 56% wetlands loss to DPs in the KMC by 2013 brings the minimum economic value lost to US$ 19,311,700 in the sampled wetlands, and projections of future wetland loss put the minimum economic loss at US$ 48,368,118 by 2040. Continuous degradation of these wetlands means serious economic costs to the government and local communities, as reflected in high replacement expenditures for wetland services, foregone incomes, subsistence livelihood support and alternative employment. The highest carbon (C) sinks were identified in forest swamps, palms, thickets and wetlands converted to agriculture, which accounted for 25% of the KMC wetlands by 2013, while the lowest total soil organic carbon (TSOC) range occurred in converted wetland cover types (converted wetlands to industrial and settlements) that occupied 47% of the study area. A general decrease in SOC sequestration from 1974 to 2013 across the KMC wetlands is identified, with the lowest C pool registered in 2013. The dwindling SOC banks are considered to be partly responsible for varying climate and related feedbacks on wetland benefits in the KMC. The hydrologic impacts of wetland loss are felt mainly in converted wetland cover types, in the form of compromised water quality, with increased nutrient pollution and TSS. These all create negative impacts on wetland hydrological services, particularly filtration, flood attenuation, recharge and discharge benefits, all of which have profound effects on biodiversity. There is an urgent need to reduce the scale of wetland diminution in the KMC. This will be achieved if mitigation and conservation measures are undertaken. Mitigation measures should include a revision of development plans, user sensitization on wetland economic values and enforcement of regulatory mechanisms. Conservation strategies should involve the use of economic incentives and disincentives which include: a revision of historic property rights to regulate wetland use, performance bonds or subsidies for environmentally friendly activities and taxes, fees or fines for unacceptable levels of degradation and tradable permits that utilise the concept of ‘wetland banks’ to ensure no further loss of the KMC wetlands to DPs. Future research should focus on modelling the response of wetland ecosystems to multiple threats and management interventions, and on a feasibility study of wetland restoration options and the implications for local people’s livelihoods in the KMC.
- Full Text:
- Date Issued: 2018
- Authors: Wasswa, Hannington
- Date: 2018
- Subjects: Wetland ecology -- Uganda -- Kampala , Wetlands -- Uganda -- Kampala Wetland management -- Uganda -- Kampala Hydrogeology
- Language: English
- Type: Thesis , Doctoral , DPhil
- Identifier: http://hdl.handle.net/10948/36409 , vital:33939
- Description: Wetland diminution for development projects (DPs) in the Kampala–Mukono Corridor (KMC) continues to pose threats to the socio-economic and ecological benefits of wetlands because decision-makers and wetland users at various levels often have insufficient knowledge of these benefits. This situation has resulted in unsustainable development decisions that accord little weight to wetlands and have allocated many of them to DPs. In order to inform decision making for optimal development in the KMC, the present study analysed the spatial and temporal wetland loss to DPs, estimated the economic value of the KMC wetlands, and assessed the environmental consequences of wetland conversion for DPs. Sets of ortho-rectified and cloud-free multi-temporal Landsat MSS (1974) and Landsat TM/ETM+ images (30m) for 1986, 2006, and 2013 were analysed in a spatial and temporal framework. The 79m Landsat image (MSS) of 1974 was resampled and later filtered with subsequent 30m images using a majority filter method. An unsupervised classification approach was employed to characterize the wetlands and associated DPs. The classified DPs and wetland cover types were validated by reference to topographical maps (sheets) of 1974 at a scale of 1:50,000 obtained from Uganda Lands and Surveys, apriori knowledge and Google earth images corresponding to the same spatial and temporal frames. The IDRISI Selva-based Markov Chain model was employed to model future wetland loss to DPs. The Total Economic Valuation Approach (TEV) was employed to quantify selected use values of wetland economic benefits using the market price, replacement cost and contingent valuation techniques. The ecological implications of wetland loss focused on soil organic carbon (SOC) and hydrological impacts in the KMC wetlands. The estimated SOC was assessed with climatic data in order to infer the implication of SOC loss for local climate variability. The manual wet chemistry/oxidation method by Walkley-Black (1934) was adopted to estimate SOC in various wetland cover types. Hydrological impact assessments focused on water quality analysis in various wetland cover types, with major parameters being total nitrogen (TN), total phosphorous (TP) total dissolved solids – (TDS) and total suspended sediments (TSS). Hydrologic flow data parameters across the different wetland cover types in the KMC focused on water level, speed, stream width, and bed load. Results from analysis of the spatial-temporal wetland change revealed that by 2013 the KMC wetlands had lost almost half (47%) of their 1974 areal coverage, with 56% of this loss resulting from conversion to DPs. It is projected that 26% of the KMC wetlands will be lost to more DPs by 2040. Wetland loss is attributed to intensified economic activity and preference of Kampala as an industrial zone, weakness in the previous spatial planning of Kampala, and the general lack of information flow to various institutions involved in the establishment of DPs. The KMC wetlands provide a flow of economic benefits at a minimum approximated value of US$ 3,418 / ha / per year. It is revealed that a great deal of these economic benefits (88%) accrues to the local subsistence level in the form of livelihood products, incomes, and employment benefits. The 56% wetlands loss to DPs in the KMC by 2013 brings the minimum economic value lost to US$ 19,311,700 in the sampled wetlands, and projections of future wetland loss put the minimum economic loss at US$ 48,368,118 by 2040. Continuous degradation of these wetlands means serious economic costs to the government and local communities, as reflected in high replacement expenditures for wetland services, foregone incomes, subsistence livelihood support and alternative employment. The highest carbon (C) sinks were identified in forest swamps, palms, thickets and wetlands converted to agriculture, which accounted for 25% of the KMC wetlands by 2013, while the lowest total soil organic carbon (TSOC) range occurred in converted wetland cover types (converted wetlands to industrial and settlements) that occupied 47% of the study area. A general decrease in SOC sequestration from 1974 to 2013 across the KMC wetlands is identified, with the lowest C pool registered in 2013. The dwindling SOC banks are considered to be partly responsible for varying climate and related feedbacks on wetland benefits in the KMC. The hydrologic impacts of wetland loss are felt mainly in converted wetland cover types, in the form of compromised water quality, with increased nutrient pollution and TSS. These all create negative impacts on wetland hydrological services, particularly filtration, flood attenuation, recharge and discharge benefits, all of which have profound effects on biodiversity. There is an urgent need to reduce the scale of wetland diminution in the KMC. This will be achieved if mitigation and conservation measures are undertaken. Mitigation measures should include a revision of development plans, user sensitization on wetland economic values and enforcement of regulatory mechanisms. Conservation strategies should involve the use of economic incentives and disincentives which include: a revision of historic property rights to regulate wetland use, performance bonds or subsidies for environmentally friendly activities and taxes, fees or fines for unacceptable levels of degradation and tradable permits that utilise the concept of ‘wetland banks’ to ensure no further loss of the KMC wetlands to DPs. Future research should focus on modelling the response of wetland ecosystems to multiple threats and management interventions, and on a feasibility study of wetland restoration options and the implications for local people’s livelihoods in the KMC.
- Full Text:
- Date Issued: 2018
The economic impact of homeland consolidation on households in the fromer Ciskei : the case of Victoria East
- Authors: Coka, Zimbini
- Date: 2018
- Subjects: Consolidation of land holdings Ciskei (South Africa) -- Economic conditions
- Language: English
- Type: Thesis , Masters , Agricultural Economics
- Identifier: http://hdl.handle.net/10353/10156 , vital:35363
- Description: This study attempts to ascertain the economic impact of the process of homeland consolidation in four communities that became part of the Ciskei. It describes the process of homeland consolidation at Lloyd, Bergplaas, Balfour and Qanda, and seeks to understand the effects of homeland consolidation on the level of economic activity in these areas. ‘Homeland consolidation’ was the official term used to describe the policy developed by the central government of South Africa in the 1970s to reduce the number of separate, isolated pieces of land making up each of the Bantustans. It was part of the ultimately unsuccessful and suspect process of turning these areas into independent ‘national states’. The Apartheid government bought out selected white farms/properties/land like in Lloyd, Bergplaas, Balfour and Qanda, and consolidated them with the adjacent homeland territory. The result of this process made commercial farmland available to black people. In a very narrow sense, this particular aspect of homeland consolidation was an antecedent of land reform. Because homeland consolidation took place some time ago, discerning the economic effects relied above all on people’s recollections of their past experiences, which could only be quantified in a very limited manner. In other words, the data and analysis were largely although not exclusively qualitative. Household and life history interviews were conducted using semi-structured questionnaires, and then the data was analyzed using content analysis, descriptive statistics, the Chi-square test and the two-proportion z test. Through the process of homeland consolidation and forced removals, people ended up losing productive land and livestock because they were forced to sell their livestock at a loss and they had no land where they were moved to. People were stripped of their livelihoods, in addition to losing a place that they called home and the loss of employment. This study also looked at the changes in farming before and during the apartheid era, during the time when the Ciskeian government was in power and after 1994 till now. And also looked at the broader perspective of what actually happened in the four sites from the life history interviews.
- Full Text:
- Date Issued: 2018
- Authors: Coka, Zimbini
- Date: 2018
- Subjects: Consolidation of land holdings Ciskei (South Africa) -- Economic conditions
- Language: English
- Type: Thesis , Masters , Agricultural Economics
- Identifier: http://hdl.handle.net/10353/10156 , vital:35363
- Description: This study attempts to ascertain the economic impact of the process of homeland consolidation in four communities that became part of the Ciskei. It describes the process of homeland consolidation at Lloyd, Bergplaas, Balfour and Qanda, and seeks to understand the effects of homeland consolidation on the level of economic activity in these areas. ‘Homeland consolidation’ was the official term used to describe the policy developed by the central government of South Africa in the 1970s to reduce the number of separate, isolated pieces of land making up each of the Bantustans. It was part of the ultimately unsuccessful and suspect process of turning these areas into independent ‘national states’. The Apartheid government bought out selected white farms/properties/land like in Lloyd, Bergplaas, Balfour and Qanda, and consolidated them with the adjacent homeland territory. The result of this process made commercial farmland available to black people. In a very narrow sense, this particular aspect of homeland consolidation was an antecedent of land reform. Because homeland consolidation took place some time ago, discerning the economic effects relied above all on people’s recollections of their past experiences, which could only be quantified in a very limited manner. In other words, the data and analysis were largely although not exclusively qualitative. Household and life history interviews were conducted using semi-structured questionnaires, and then the data was analyzed using content analysis, descriptive statistics, the Chi-square test and the two-proportion z test. Through the process of homeland consolidation and forced removals, people ended up losing productive land and livestock because they were forced to sell their livestock at a loss and they had no land where they were moved to. People were stripped of their livelihoods, in addition to losing a place that they called home and the loss of employment. This study also looked at the changes in farming before and during the apartheid era, during the time when the Ciskeian government was in power and after 1994 till now. And also looked at the broader perspective of what actually happened in the four sites from the life history interviews.
- Full Text:
- Date Issued: 2018
The effect of annealing and beta irradiation on thermoluminescence spectra of α-Al2O3: C, Mg
- Kalita, Jitumani M, Chithambo, Makaiko L
- Authors: Kalita, Jitumani M , Chithambo, Makaiko L
- Date: 2018
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/112875 , vital:33669 , https://doi.org/10.1016/j.jlumin.2017.12.036
- Description: The effect of annealing on thermoluminescence spectra of beta irradiated α-Al2O3:C,Mg has been studied. Measurements were made on an un-annealed sample and samples annealed at 600, 700 and 900 °C. A glow curve measured at 1 °C/s from samples irradiated to 1 Gy shows a high intensity peak at 163 °C and six secondary peaks of weaker intensity at 43, 73, 195, 280, 329 and 370 °C. When the samples are annealed at 700 or 900 °C, an additional secondary peak appears at 100 °C. The thermoluminescence spectrum of an un-annealed sample measured at 1 °C/s between 300 and 700 nm shows the main emission band at ~ 410 nm and subsidiary emission bands at ~ 325 and 485 nm. The emission from samples annealed at 700 and 900 °C show similar bands except for a decrease in intensity of the emission at 485 nm. The emission bands at 325, 410 and 485 nm are attributed to F+, F and F22+(2Mg) -centres respectively. The decrease of the emission band at 485 nm is deduced to be due to the destruction of the F22+(2Mg) centre at 700 °C. The emission bands are unaffected by irradiation dose between 10 and 320 Gy. However, when the sample is annealed at or beyond 700 °C, any effects on the F+ and F centres emission can be easier distinguished particularly for doses greater than 10 Gy.
- Full Text: false
- Date Issued: 2018
- Authors: Kalita, Jitumani M , Chithambo, Makaiko L
- Date: 2018
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/112875 , vital:33669 , https://doi.org/10.1016/j.jlumin.2017.12.036
- Description: The effect of annealing on thermoluminescence spectra of beta irradiated α-Al2O3:C,Mg has been studied. Measurements were made on an un-annealed sample and samples annealed at 600, 700 and 900 °C. A glow curve measured at 1 °C/s from samples irradiated to 1 Gy shows a high intensity peak at 163 °C and six secondary peaks of weaker intensity at 43, 73, 195, 280, 329 and 370 °C. When the samples are annealed at 700 or 900 °C, an additional secondary peak appears at 100 °C. The thermoluminescence spectrum of an un-annealed sample measured at 1 °C/s between 300 and 700 nm shows the main emission band at ~ 410 nm and subsidiary emission bands at ~ 325 and 485 nm. The emission from samples annealed at 700 and 900 °C show similar bands except for a decrease in intensity of the emission at 485 nm. The emission bands at 325, 410 and 485 nm are attributed to F+, F and F22+(2Mg) -centres respectively. The decrease of the emission band at 485 nm is deduced to be due to the destruction of the F22+(2Mg) centre at 700 °C. The emission bands are unaffected by irradiation dose between 10 and 320 Gy. However, when the sample is annealed at or beyond 700 °C, any effects on the F+ and F centres emission can be easier distinguished particularly for doses greater than 10 Gy.
- Full Text: false
- Date Issued: 2018
The effect of casuarina trees on sea turtles nesting beaches throughout the Indian Ocean and South-East Asia regions: A beach vulnerability assessment
- Authors: De Vos, Deidre
- Date: 2018
- Subjects: Conservation biology , Casuarina Sea turtles
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/22420 , vital:29968
- Description: Rapid global change and anthropogenic modification of natural habitats are threatening ecosystems across the globe. Many of these threats and adverse impacts are concentrated on the world’s coastlines, with a large portion of the global population choosing to live next to the coast. To accommodate coastal populations and their related activities, the dynamic littoral active zone is often stabilized with hard engineering structures such as sea walls, which disrupt coastal ecological processes. Most natural coastal processes have since become natural disaster risks to the anthropogenically-modified coasts. Coastal stabilization has led to “coastal squeeze” with modified shorelines unable to respond naturally to changes in sea level. Furthermore, global change through global ‘warming’ exacerbates sea level rise. The combined impacts result in permanent/episodic inundation and coastal erosion, which may damage human settlements and degrade or destroy coastal habitat. As an alternative to hard armouring structures like sea walls, ‘soft’ options like large-scale plantations of trees as bio-shields are used as a ‘green’ option to protect developed coasts. Indeed, green shelter belts have rapidly increased since the December 2004 tsunami event in the Indian Ocean and South-East Asian (IOSEA) region. Extensive portions of the coastal habitat, including sensitive sea turtle nesting habitat, have been modified by planting exotic vegetation. Two invasive species, Casuarina equisetifolia and Casuarina glauca, are regularly used for coastal dune stabilization or as bio-shields because they are adapted to arid conditions, high salinity and low soil fertility typical of beach systems. The functionality of Casuarina trees as a ‘comprehensive’ coastal protection tool, however, has yet to be tested and the effects of Casuarina on sandy beach ecosystems remain largely unquantified. There is no empirical evidence to support the claim that Casuarina trees adequately function as a storm protection measure, and other studies have suggested that Casuarina species have adverse effects on sandy beach ecosystems, including the promotion of erosion in some instances and negative impacts on fauna, including sea turtles. This study investigated the potential value of non-native Casuarina trees as a coastal protection measure on sea turtle nesting beaches taking into consideration the potential impacts of global change. First, the study estimated local scale effects of Casuarina trees within the South African sea turtle nesting rookery in the iSimangaliso Wetland Park by measuring impacts on back-beach substrate characteristics and shape. A few metrics were unaffected, such as grain size, sand penetrability and sand moisture, but sand pH and sand temperature were significantly lower underneath Casuarina stands. A mean pH of 8.2 and a median temperature of 26 ± SD1.5oC were recorded under Casuarina trees and a pH of 9 and a median temperature of 27.2 ± SD1.9oC under native vegetation. The significantly lower, more stable average temperature underneath Casuarina trees may have significant implications for sex ratios of sea turtles as the sex of sea turtles is determined by temperature; Temperatures above 32°C will yield all females and temperatures below 28°C will produce only males, with a pivotal temperature at which a 1:1 sex ratio is developed is about 29°C. Furthermore, sand temperature underneath Casuarina trees is less likely to reach lethal temperatures (above ~33°C) that could lead to hatchling mortality than in areas with no vegetation. So, in terms of hatchling success, the thermal environment created by Casuarina trees might be favourable in extremely hot climate areas, especially when considering the effects of climate change. Casuarina trees, however, affect back-beach and dune dynamics by altering sand movement. Semi-quantitative and qualitative analyses of beach profiles suggested that Casuarina trees and shrubs result in wind scouring directly in front of the foredunes as evidenced by the concave shape in front of Casuarina stands at some sites. Sites with natural vegetation had mainly convex beach shapes, suggesting sand accretion. Either way, vegetation had an important effect on sand dynamics (both positive and negative) where areas with no vegetation (bare sand) only had a neutral/straight shape. There was, however, a significant interaction between vegetation type and site, indicating that vegetation type alone cannot account for all the differences in beach profile dynamics and that site-specific conditions like wave height, sand budget, precipitation and orientation differences among locations may also have an effect. The second part of the study had a regional perspective, investigating the effect of Casuarina trees on 50 sea turtle nesting beaches across the Indian Ocean South East Asia (IOSEA) region. The study first derived an appropriate (novel) beach vulnerability index using features that drive beach erosion. The index was then applied to 50 turtle rookeries in the presence/absence of Casuarina trees. The study noted the extensive distribution of exotic Casuarina trees throughout the IOSEA region and established that 28% of the 50 selected sea turtle nesting beaches had non-native Casuarina present. There was no significant difference in the erosion vulnerability of beaches with and without Casuarina based on the existing indicators. However, the study did show that seven important sea turtle rookeries were highly vulnerable to erosion, some with extensive exotic Casuarina stands. Olive ridley (Lepidochelys olivacea) nesting beaches in India, were dominated by Casuarina trees and were highly vulnerable to erosion. The study showed that the presence of Casuarina trees alone could not be viewed as an indicator of erosion but could be a contributing factor, as several other drivers like narrow back-beach width, absence of dunes and development on exposed coasts prone to storms, also contribute to the high erosion vulnerability of beaches. The study questions the use of exotic vegetation, such as Casuarina species, for coastal protection by demonstrating local scale effects on the back-beach environment and provides a comprehensive overview of the erosion potential of sea turtle nesting beaches throughout the IOSEA region.
- Full Text:
- Date Issued: 2018
- Authors: De Vos, Deidre
- Date: 2018
- Subjects: Conservation biology , Casuarina Sea turtles
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/22420 , vital:29968
- Description: Rapid global change and anthropogenic modification of natural habitats are threatening ecosystems across the globe. Many of these threats and adverse impacts are concentrated on the world’s coastlines, with a large portion of the global population choosing to live next to the coast. To accommodate coastal populations and their related activities, the dynamic littoral active zone is often stabilized with hard engineering structures such as sea walls, which disrupt coastal ecological processes. Most natural coastal processes have since become natural disaster risks to the anthropogenically-modified coasts. Coastal stabilization has led to “coastal squeeze” with modified shorelines unable to respond naturally to changes in sea level. Furthermore, global change through global ‘warming’ exacerbates sea level rise. The combined impacts result in permanent/episodic inundation and coastal erosion, which may damage human settlements and degrade or destroy coastal habitat. As an alternative to hard armouring structures like sea walls, ‘soft’ options like large-scale plantations of trees as bio-shields are used as a ‘green’ option to protect developed coasts. Indeed, green shelter belts have rapidly increased since the December 2004 tsunami event in the Indian Ocean and South-East Asian (IOSEA) region. Extensive portions of the coastal habitat, including sensitive sea turtle nesting habitat, have been modified by planting exotic vegetation. Two invasive species, Casuarina equisetifolia and Casuarina glauca, are regularly used for coastal dune stabilization or as bio-shields because they are adapted to arid conditions, high salinity and low soil fertility typical of beach systems. The functionality of Casuarina trees as a ‘comprehensive’ coastal protection tool, however, has yet to be tested and the effects of Casuarina on sandy beach ecosystems remain largely unquantified. There is no empirical evidence to support the claim that Casuarina trees adequately function as a storm protection measure, and other studies have suggested that Casuarina species have adverse effects on sandy beach ecosystems, including the promotion of erosion in some instances and negative impacts on fauna, including sea turtles. This study investigated the potential value of non-native Casuarina trees as a coastal protection measure on sea turtle nesting beaches taking into consideration the potential impacts of global change. First, the study estimated local scale effects of Casuarina trees within the South African sea turtle nesting rookery in the iSimangaliso Wetland Park by measuring impacts on back-beach substrate characteristics and shape. A few metrics were unaffected, such as grain size, sand penetrability and sand moisture, but sand pH and sand temperature were significantly lower underneath Casuarina stands. A mean pH of 8.2 and a median temperature of 26 ± SD1.5oC were recorded under Casuarina trees and a pH of 9 and a median temperature of 27.2 ± SD1.9oC under native vegetation. The significantly lower, more stable average temperature underneath Casuarina trees may have significant implications for sex ratios of sea turtles as the sex of sea turtles is determined by temperature; Temperatures above 32°C will yield all females and temperatures below 28°C will produce only males, with a pivotal temperature at which a 1:1 sex ratio is developed is about 29°C. Furthermore, sand temperature underneath Casuarina trees is less likely to reach lethal temperatures (above ~33°C) that could lead to hatchling mortality than in areas with no vegetation. So, in terms of hatchling success, the thermal environment created by Casuarina trees might be favourable in extremely hot climate areas, especially when considering the effects of climate change. Casuarina trees, however, affect back-beach and dune dynamics by altering sand movement. Semi-quantitative and qualitative analyses of beach profiles suggested that Casuarina trees and shrubs result in wind scouring directly in front of the foredunes as evidenced by the concave shape in front of Casuarina stands at some sites. Sites with natural vegetation had mainly convex beach shapes, suggesting sand accretion. Either way, vegetation had an important effect on sand dynamics (both positive and negative) where areas with no vegetation (bare sand) only had a neutral/straight shape. There was, however, a significant interaction between vegetation type and site, indicating that vegetation type alone cannot account for all the differences in beach profile dynamics and that site-specific conditions like wave height, sand budget, precipitation and orientation differences among locations may also have an effect. The second part of the study had a regional perspective, investigating the effect of Casuarina trees on 50 sea turtle nesting beaches across the Indian Ocean South East Asia (IOSEA) region. The study first derived an appropriate (novel) beach vulnerability index using features that drive beach erosion. The index was then applied to 50 turtle rookeries in the presence/absence of Casuarina trees. The study noted the extensive distribution of exotic Casuarina trees throughout the IOSEA region and established that 28% of the 50 selected sea turtle nesting beaches had non-native Casuarina present. There was no significant difference in the erosion vulnerability of beaches with and without Casuarina based on the existing indicators. However, the study did show that seven important sea turtle rookeries were highly vulnerable to erosion, some with extensive exotic Casuarina stands. Olive ridley (Lepidochelys olivacea) nesting beaches in India, were dominated by Casuarina trees and were highly vulnerable to erosion. The study showed that the presence of Casuarina trees alone could not be viewed as an indicator of erosion but could be a contributing factor, as several other drivers like narrow back-beach width, absence of dunes and development on exposed coasts prone to storms, also contribute to the high erosion vulnerability of beaches. The study questions the use of exotic vegetation, such as Casuarina species, for coastal protection by demonstrating local scale effects on the back-beach environment and provides a comprehensive overview of the erosion potential of sea turtle nesting beaches throughout the IOSEA region.
- Full Text:
- Date Issued: 2018
The effect of ER stress in INS-1E cells using IL-1β under hyperglycaemic conditions
- Authors: Jackson, Simon
- Date: 2018
- Subjects: Diabetes -- Pathogenesis , Endoplasmic reticulum -- Pathophysiology Endoplasmic reticulum Diabetes
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/30397 , vital:30938
- Description: Diabetes afflicts millions of individuals worldwide, and the statistics rise each year. It is associated with various ailments which reduce the quality of life and has been shown to be associated with seemingly unrelated diseases or conditions. One aspect of the pathogenesis of diabetes is endoplasmic reticulum (ER) stress, which is an imbalance in the protein loading and protein folding capacities of the ER of a cell. Under chronic hyperglycaemic conditions associated with the development of diabetes, excessive insulin production disrupts the ER homeostasis, leading to ER stress. If the ER stress is severe or chronic, cell death of pancreatic β-cells may occur, leading to the onset of diabetes. There is currently a gap in available models that closely resemble the pathogenesis of diabetes in insulinoma-1E (INS-1E) pancreatic β-cells to study ER stress under hyperglycaemic conditions. This study optimised various ER stress-inducing models and tested terpenoid treatments to investigate their potential in modulating ER stress. Using various cell viability assays, five models to induce ER stress were optimised (hyperglycaemic, interleukin-1β (IL-1β), tunicamycin (Tm), brefeldin-A (BFA) and thapsigargin (Tg)). The five models were shown to induce ER stress through the expression of the downstream ER stress marker CCAAT-enhancer binding protein (C/EBP) homologous protein (CHOP). The various models induced ER stress under different mechanisms. Insulin secretion analysis using enzyme-linked immunosorbent assays (ELISAs) demonstrated that low concentrations of IL-1β promoted insulin secretion. Several of the terpenoid treatments showed potential in alleviating different aspects of either ER stress or inflammation.
- Full Text:
- Date Issued: 2018
- Authors: Jackson, Simon
- Date: 2018
- Subjects: Diabetes -- Pathogenesis , Endoplasmic reticulum -- Pathophysiology Endoplasmic reticulum Diabetes
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/30397 , vital:30938
- Description: Diabetes afflicts millions of individuals worldwide, and the statistics rise each year. It is associated with various ailments which reduce the quality of life and has been shown to be associated with seemingly unrelated diseases or conditions. One aspect of the pathogenesis of diabetes is endoplasmic reticulum (ER) stress, which is an imbalance in the protein loading and protein folding capacities of the ER of a cell. Under chronic hyperglycaemic conditions associated with the development of diabetes, excessive insulin production disrupts the ER homeostasis, leading to ER stress. If the ER stress is severe or chronic, cell death of pancreatic β-cells may occur, leading to the onset of diabetes. There is currently a gap in available models that closely resemble the pathogenesis of diabetes in insulinoma-1E (INS-1E) pancreatic β-cells to study ER stress under hyperglycaemic conditions. This study optimised various ER stress-inducing models and tested terpenoid treatments to investigate their potential in modulating ER stress. Using various cell viability assays, five models to induce ER stress were optimised (hyperglycaemic, interleukin-1β (IL-1β), tunicamycin (Tm), brefeldin-A (BFA) and thapsigargin (Tg)). The five models were shown to induce ER stress through the expression of the downstream ER stress marker CCAAT-enhancer binding protein (C/EBP) homologous protein (CHOP). The various models induced ER stress under different mechanisms. Insulin secretion analysis using enzyme-linked immunosorbent assays (ELISAs) demonstrated that low concentrations of IL-1β promoted insulin secretion. Several of the terpenoid treatments showed potential in alleviating different aspects of either ER stress or inflammation.
- Full Text:
- Date Issued: 2018
The effect of guided enquiry-based learning approach on electrical engineering students' recall ability, conceptual understanding, problem solving skills and critical thinking ability in power electronics course at a selected university in South Africa
- Authors: Kumar, Vinod
- Date: 2018
- Subjects: Power electronics Power electronics -- Problems, exercises -- South Africa
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10353/8474 , vital:32836
- Description: Power Electronics (PE) forms the major part of the syllabus for the Industrial Electronics (INDE) course of the National Diploma (ND) programme in Electrical Engineering. This study investigated the effect of Guided Enquiry-Based Learning (GEBL), an Active Learning (AL) approach on Electrical Engineering students’ recall ability, conceptual understanding of PE, problem solving skills and critical thinking ability. The study was carried out at one of the campuses of a selected university in South Africa’s Eastern Cape Province in an attempt to check if GEBL would improve student performances in the above focused areas. The expected population for this research in 2017 was 21, similar to the numbers enrolled in 2016. However, in 2017 the enrollment dropped to 14 and this posed a limitation. Since cancelling the study due to the drop in enrollment would have caused the loss of a research report on PE students, it was decided to continue with it. This was especially so, since no other report on PE within South Africa could be located. The instruments were developed using inputs from subject experts to ensure content validity. Cronbach’s Alpha was used to test the reliability of the instrument. A pilot study was conducted during the previous year with the 2016 PE students and deficiencies in the instruments were rectified. Out of the 14 students in 2017, seven volunteered to be taught using the GEBL approach. All ethical considerations applicable to the study were adhered to. All students from the GEBL group signed the informed consent forms prior to the study. The study adopted a pragmatist paradigm and a mixed method approach. A quasi experimental non-equivalent group post-test only research design was used where both the experimental group and the control group were selected (without random assignment). The post-test only design was selected because of the time constraints with the semester courses. A student-centred GEBL approach was used as an intervention for the experimental group and a teacher-centred traditional approach was used for the control group. Students from both the GEBL and Traditionally Taught Groups (TTGs) were subjected to the same assessments. Quantitative data were collected from two formative assessments and one summative assessment and the qualitative data were collected by interviewing all students from the GEBL group. The collected data were statistically and thematically analysed to determine the extent to which the intervention affected the students’ recall ability, conceptual understanding of PE, problem solving skills and their critical thinking ability. The main conclusions were that when compared to the traditional approach, GEBL was significantly more effective in enhancing recall as well as understanding of PE concepts. However, significant differences were not evident in problem solving and critical thinking. The recommendations are that: students must be encouraged to be more active in the learning process; the shift of strategy from traditional to AL methods such as GEBL must be introduced gradually; and the benefits of GEBL and exposure to it must be popularised in order to develop positive attitudes to GEBL not only among students, but also teaching staff.
- Full Text:
- Date Issued: 2018
- Authors: Kumar, Vinod
- Date: 2018
- Subjects: Power electronics Power electronics -- Problems, exercises -- South Africa
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10353/8474 , vital:32836
- Description: Power Electronics (PE) forms the major part of the syllabus for the Industrial Electronics (INDE) course of the National Diploma (ND) programme in Electrical Engineering. This study investigated the effect of Guided Enquiry-Based Learning (GEBL), an Active Learning (AL) approach on Electrical Engineering students’ recall ability, conceptual understanding of PE, problem solving skills and critical thinking ability. The study was carried out at one of the campuses of a selected university in South Africa’s Eastern Cape Province in an attempt to check if GEBL would improve student performances in the above focused areas. The expected population for this research in 2017 was 21, similar to the numbers enrolled in 2016. However, in 2017 the enrollment dropped to 14 and this posed a limitation. Since cancelling the study due to the drop in enrollment would have caused the loss of a research report on PE students, it was decided to continue with it. This was especially so, since no other report on PE within South Africa could be located. The instruments were developed using inputs from subject experts to ensure content validity. Cronbach’s Alpha was used to test the reliability of the instrument. A pilot study was conducted during the previous year with the 2016 PE students and deficiencies in the instruments were rectified. Out of the 14 students in 2017, seven volunteered to be taught using the GEBL approach. All ethical considerations applicable to the study were adhered to. All students from the GEBL group signed the informed consent forms prior to the study. The study adopted a pragmatist paradigm and a mixed method approach. A quasi experimental non-equivalent group post-test only research design was used where both the experimental group and the control group were selected (without random assignment). The post-test only design was selected because of the time constraints with the semester courses. A student-centred GEBL approach was used as an intervention for the experimental group and a teacher-centred traditional approach was used for the control group. Students from both the GEBL and Traditionally Taught Groups (TTGs) were subjected to the same assessments. Quantitative data were collected from two formative assessments and one summative assessment and the qualitative data were collected by interviewing all students from the GEBL group. The collected data were statistically and thematically analysed to determine the extent to which the intervention affected the students’ recall ability, conceptual understanding of PE, problem solving skills and their critical thinking ability. The main conclusions were that when compared to the traditional approach, GEBL was significantly more effective in enhancing recall as well as understanding of PE concepts. However, significant differences were not evident in problem solving and critical thinking. The recommendations are that: students must be encouraged to be more active in the learning process; the shift of strategy from traditional to AL methods such as GEBL must be introduced gradually; and the benefits of GEBL and exposure to it must be popularised in order to develop positive attitudes to GEBL not only among students, but also teaching staff.
- Full Text:
- Date Issued: 2018
The effect of human resources management practices on employee commitment: the case of Mnquma Local Municipality
- Fihla, Siphenathi https://orcid.org/0000-0001-9632-2650
- Authors: Fihla, Siphenathi https://orcid.org/0000-0001-9632-2650
- Date: 2018
- Subjects: Personnel management--South Africa , Municipal government--South Africa
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10353/24431 , vital:62790
- Description: This study evaluated the relationship between the Human Resource Management Practices (HRMP) and employee commitment. Results based on a sample from Mnquma Local Municipality indicate that these practices have a significant impact on employee commitment. This project will help to advance research on exploring the influence of organisational variables on commitment. Research purpose: The purpose of the study was to investigate the effects of human resources management practices on employee commitment at Mnquma Local Municipality. Motivation for the study: The study examines HRMP and employee commitment in the public sector. The relationship between the two may be of value to the municipality’s success. Research approach, design and method: A quantitative research approach was followed to carry out this study. Data were collected from a sample of 137 respondents in a selected municipality (Mnquma Local Municipality). A self-administered questionnaire was sent to respondents. Main findings: A significant relationship was found between HRMP and employee commitment. Practical or managerial implications: Findings may be relevant to practitioners, including strategic management researchers, policy-makers, directors, managers, and supervisors. The study could assist various practitioners directly or indirectly involved in private and public organisations to develop HRMP that improves employee commitment. Contribution or value-add: The study adds to the literature on HRMP and employee commitment among the public service. , Thesis (MCom) -- Faculty of Management and Commerce, 2018
- Full Text:
- Date Issued: 2018
- Authors: Fihla, Siphenathi https://orcid.org/0000-0001-9632-2650
- Date: 2018
- Subjects: Personnel management--South Africa , Municipal government--South Africa
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10353/24431 , vital:62790
- Description: This study evaluated the relationship between the Human Resource Management Practices (HRMP) and employee commitment. Results based on a sample from Mnquma Local Municipality indicate that these practices have a significant impact on employee commitment. This project will help to advance research on exploring the influence of organisational variables on commitment. Research purpose: The purpose of the study was to investigate the effects of human resources management practices on employee commitment at Mnquma Local Municipality. Motivation for the study: The study examines HRMP and employee commitment in the public sector. The relationship between the two may be of value to the municipality’s success. Research approach, design and method: A quantitative research approach was followed to carry out this study. Data were collected from a sample of 137 respondents in a selected municipality (Mnquma Local Municipality). A self-administered questionnaire was sent to respondents. Main findings: A significant relationship was found between HRMP and employee commitment. Practical or managerial implications: Findings may be relevant to practitioners, including strategic management researchers, policy-makers, directors, managers, and supervisors. The study could assist various practitioners directly or indirectly involved in private and public organisations to develop HRMP that improves employee commitment. Contribution or value-add: The study adds to the literature on HRMP and employee commitment among the public service. , Thesis (MCom) -- Faculty of Management and Commerce, 2018
- Full Text:
- Date Issued: 2018