Steam activation, characterisation and adsorption studies of activated carbon from maize tassels.
- Olorundare, O F, Msagati, Titus A, Krause, Rui W M, Okonkwo, J O, Mamba, Bhekie B
- Authors: Olorundare, O F , Msagati, Titus A , Krause, Rui W M , Okonkwo, J O , Mamba, Bhekie B
- Date: 2014
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/123847 , vital:35507 , https://doi.org/10.1080/02757540.2013.877001
- Description: In this paper, steam-produced activated carbon (STAC) from maize tassel (MT) was evaluated for its ability to remove basic dye (methylene blue MB) from aqueous solution in a batch adsorption process. The equilibrium experiments were conducted in the range of 50–300 mg/L initial MB concentrations at 30°C, for effect of pH, adsorbent dosage and contact time. The experimental data were analysed by Langmuir, Freundlich and Temkin isotherm models of adsorption. Freundlich adsorption isotherm was found to have highest value of R2(R2=0.97) compared to other models of Langmuir and Temkin having (0.96 and 0.95 respectively). STAC has a high adsorptive capacity for MB dye (200 mg/g) and also showed favourable adsorption for the dye with the separation factor for the dye-activated carbon system. The kinetic data obtained were analysed using pseudo first-order kinetic equation and pseudo second-order kinetic equation. The experimental data fitted well into pseudo second-order kinetic equation, as demonstrated by the high value of R2.
- Full Text:
- Date Issued: 2014
- Authors: Olorundare, O F , Msagati, Titus A , Krause, Rui W M , Okonkwo, J O , Mamba, Bhekie B
- Date: 2014
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/123847 , vital:35507 , https://doi.org/10.1080/02757540.2013.877001
- Description: In this paper, steam-produced activated carbon (STAC) from maize tassel (MT) was evaluated for its ability to remove basic dye (methylene blue MB) from aqueous solution in a batch adsorption process. The equilibrium experiments were conducted in the range of 50–300 mg/L initial MB concentrations at 30°C, for effect of pH, adsorbent dosage and contact time. The experimental data were analysed by Langmuir, Freundlich and Temkin isotherm models of adsorption. Freundlich adsorption isotherm was found to have highest value of R2(R2=0.97) compared to other models of Langmuir and Temkin having (0.96 and 0.95 respectively). STAC has a high adsorptive capacity for MB dye (200 mg/g) and also showed favourable adsorption for the dye with the separation factor for the dye-activated carbon system. The kinetic data obtained were analysed using pseudo first-order kinetic equation and pseudo second-order kinetic equation. The experimental data fitted well into pseudo second-order kinetic equation, as demonstrated by the high value of R2.
- Full Text:
- Date Issued: 2014
Storying the career development of black South African female university students
- Authors: Chetty, Candice
- Date: 2014
- Subjects: Career development , Counseling in higher education , College students, Black
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:9974 , http://hdl.handle.net/10948/d1021056
- Description: Career psychology in South Africa has traditionally been constituted by assessment methods, counselling practices and research objectives of a modernist-positivist paradigm. This paradigm has been limited in its consideration and integration of the broad range of contextual factors that may influence the career development of individuals. This study is based on the Systems Theory Framework of career development, an overarching theoretical framework of career development that is able to acknowledge the complexity of career development processes and assist in engaging with contexts of that complexity. Seven Xhosa-speaking Black South African female university students were invited to story their career development within their unique individual contexts. In collaborating with the participants, the study adopted an exploratory collective case study research design. The My Systems of Career Influences reflection process was primarily used to obtain the qualitative data. Based on the need that arose in the career counselling process, the quantitative data were generated from the Values Scale (VS), the Life Roles Inventory (LRI), the Commitment to Career Choices Scale (CCCS), and the Jung Personality Questionnaire (JPQ). The study is particularly relevant given the growing need for the development of non-discriminatory career assessment and counselling collaborations between counsellors and clients who need to navigate unique and diverse South African contexts. Key words: career counselling, career development, constructivism, My System of Career Influences (MSCI), narrative career counselling, qualitative career assessment, South African female university students, storytelling approach, Systems Theory Framework (STF).
- Full Text:
- Date Issued: 2014
- Authors: Chetty, Candice
- Date: 2014
- Subjects: Career development , Counseling in higher education , College students, Black
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:9974 , http://hdl.handle.net/10948/d1021056
- Description: Career psychology in South Africa has traditionally been constituted by assessment methods, counselling practices and research objectives of a modernist-positivist paradigm. This paradigm has been limited in its consideration and integration of the broad range of contextual factors that may influence the career development of individuals. This study is based on the Systems Theory Framework of career development, an overarching theoretical framework of career development that is able to acknowledge the complexity of career development processes and assist in engaging with contexts of that complexity. Seven Xhosa-speaking Black South African female university students were invited to story their career development within their unique individual contexts. In collaborating with the participants, the study adopted an exploratory collective case study research design. The My Systems of Career Influences reflection process was primarily used to obtain the qualitative data. Based on the need that arose in the career counselling process, the quantitative data were generated from the Values Scale (VS), the Life Roles Inventory (LRI), the Commitment to Career Choices Scale (CCCS), and the Jung Personality Questionnaire (JPQ). The study is particularly relevant given the growing need for the development of non-discriminatory career assessment and counselling collaborations between counsellors and clients who need to navigate unique and diverse South African contexts. Key words: career counselling, career development, constructivism, My System of Career Influences (MSCI), narrative career counselling, qualitative career assessment, South African female university students, storytelling approach, Systems Theory Framework (STF).
- Full Text:
- Date Issued: 2014
Strategies for promoting ethics within the SAPS
- Authors: McCarthy, Charlton Shamus
- Date: 2014
- Subjects: Police ethics -- South Africa , Law enforcement -- Moral and ethical aspects , Police -- South Africa -- Conduct of life
- Language: English
- Type: Thesis , Masters , MTech
- Identifier: http://hdl.handle.net/10948/8553 , vital:26406
- Description: Corruption and unethical management is a legitimate global concern as it can have a direct and substantial impact on the longevity and the success of an organisation, and a country. As a result much attention has been given to unethical behavior and organisational ethical violations over the last decade. Recent events have indicated that ethics management is an organisational concern with mammoth implications for organisations. The aim of this study was to investigate the development of strategies for the promotion of ethics and the impact of unethical conduct on an organisation. A direct link exists between employee behaviour and the organisational environment. The desired ethical environment is negatively affected if the employees cannot distinguish between right and wrong and do not act ethically when confronted with ethical dilemmas. Proposed ethics strategies may also be impacted on by the unethical behaviour of the leadership of organisations, compliance with legislation and poorly managed ethics strategies. The main research problem in this study was to identify what strategies could be adopted to create an ethical culture within an organisation. To achieve this objective a model was developed, proposed and supported with literature and the research study. A research questionnaire was designed to obtain the relevant data that was distributed to previously identified respondents. The results indicated that the majority employees were of the view that the organisational environment and leadership was not ethical and that the majority of employees were not actively pursuing an ethical environment. Findings indicated that the majority of employees felt that contributing factors to achieve an ethical environment was present, but ethic strategies were ineffective and poorly managed. The proposed study model, when implemented successfully, would allow the organisation the effective application of ethic interventions.
- Full Text:
- Date Issued: 2014
- Authors: McCarthy, Charlton Shamus
- Date: 2014
- Subjects: Police ethics -- South Africa , Law enforcement -- Moral and ethical aspects , Police -- South Africa -- Conduct of life
- Language: English
- Type: Thesis , Masters , MTech
- Identifier: http://hdl.handle.net/10948/8553 , vital:26406
- Description: Corruption and unethical management is a legitimate global concern as it can have a direct and substantial impact on the longevity and the success of an organisation, and a country. As a result much attention has been given to unethical behavior and organisational ethical violations over the last decade. Recent events have indicated that ethics management is an organisational concern with mammoth implications for organisations. The aim of this study was to investigate the development of strategies for the promotion of ethics and the impact of unethical conduct on an organisation. A direct link exists between employee behaviour and the organisational environment. The desired ethical environment is negatively affected if the employees cannot distinguish between right and wrong and do not act ethically when confronted with ethical dilemmas. Proposed ethics strategies may also be impacted on by the unethical behaviour of the leadership of organisations, compliance with legislation and poorly managed ethics strategies. The main research problem in this study was to identify what strategies could be adopted to create an ethical culture within an organisation. To achieve this objective a model was developed, proposed and supported with literature and the research study. A research questionnaire was designed to obtain the relevant data that was distributed to previously identified respondents. The results indicated that the majority employees were of the view that the organisational environment and leadership was not ethical and that the majority of employees were not actively pursuing an ethical environment. Findings indicated that the majority of employees felt that contributing factors to achieve an ethical environment was present, but ethic strategies were ineffective and poorly managed. The proposed study model, when implemented successfully, would allow the organisation the effective application of ethic interventions.
- Full Text:
- Date Issued: 2014
Strategies for the implementation of clinical practice guidelines in the intensive care : a systematic review
- Authors: Mpasa, Ferestas
- Date: 2014
- Subjects: Systematic reviews (Medical research) , Physician practice patterns , Intensive care units
- Language: English
- Type: Thesis , Masters , MCur
- Identifier: vital:10059 , http://hdl.handle.net/10948/d1020046
- Description: Implementation strategies for the use of clinical practice guidelines are an integral component in bridging the gap between the best research evidence and clinical practice. However, despite some remarkable investments in health research regarding clinical practice guidelines implementation strategies, it is not yet known which of these are the most effective for intensive care units. The purpose of this research study was to systematically identify and /or search, appraise, extract and synthesize the best available evidence for clinical practice guidelines implementation strategies in intensive care units, in order to develop a draft guideline for clinical practice guidelines implementation strategies in the intensive care units. A systematic review design was used to systematically identify and /or search, appraise, extract and synthesize the best available evidence from the eligible included Level 2 studies (randomized controlled trials and quasi-experimental studies). Level 2 studies were applicable because they present robust evidence in the research results regarding effectiveness of clinical practice guideline implementation strategies. Furthermore, although other systematic reviews conducted in this area before, they included studies of In addition, no systematic review was identified that reviewed Level 2 studies and developed a guideline for clinical practice guideline implementation strategies in the intensive care units. Hence, including only Level 2 studies was distinctive to this research study. Databases searched included: CINAHL with full text, Google Scholar, Academic search complete, Cochrane Register for Randomized Controlled Trials Issue 8 of 12, August 2013, and MEDLINE via PUBMED. Hand search in bound journals was also done. The search strategy identified 315 potentially relevant studies. After the process of critical appraisal, thirteen Level 2 studies were identified as relevant for the review. Of the 13 relevant studies, 10 were randomized controlled trials and three were quasi experimental studies. After the critical appraisal ten RCTs were included in the systematic review. Three studies (quasi-experimental) were excluded on the basis of methodological quality after the critical appraisal and agreement by the two independent reviewers. The Joanna Briggs Institute Critical Appraisal MASTARI Instrument for Randomized Controlled trials/ Experimental studies, and The Joanna Briggs Institute data extraction tools were used to critically appraise, and extract data from the ten included randomized controlled trials. The two reviewers who performed the critical appraisal were qualified critical care professional nurses and experts in research methodology. These reviewers conducted the critical appraisal independently to ensure the objectivity of the process. Appropriate ethical considerations were maintained throughout the process of the research study. The results indicated that 80 percent of the included studies were conducted in adult intensive care units while 20 percent were conducted in the neonatal intensive care units. Furthermore, 60 percent of the studies were conducted in the United States of America, 10 percent in France, a further 10 percent in Taiwan, another 10 percent in England and yet another 10 percfent was conducted in Australia and Newzealand. The included studies utilized more than one (multifaceted) implementation strategies to implement clinical practice guidelines in the intensive care units. The first most utilized were: printed educational materials; Information/ educational sessions/meetings; audit and feedback and champion/local opinion leaders; seconded by educational outreach visits; and computer or internet usage. Third most used were active/passive reminders; systems support; academic detailing/ one-on-one sessions teleconferences/videoconferences and workshops/in services. Fourth most used were ollaboration/interdisciplinary teams; slide shows, teleconferences/videoconferences and discussions. Fifth most used were practical training; monitoring visits and grand rounds. However all the strategies were of equal importance. Conclusively, the included studies utilized multifaceted implementation strategies. However, no study indicated the use of a guideline for the implementation strategies in the process of clinical practice guidelines implementation. The systematic review developed a draft guideline for clinical practice guideline implementation strategies in the intensive care units. The guideline will enhance effective implementation of clinical practice guidelines in such a complex environment.
- Full Text:
- Date Issued: 2014
- Authors: Mpasa, Ferestas
- Date: 2014
- Subjects: Systematic reviews (Medical research) , Physician practice patterns , Intensive care units
- Language: English
- Type: Thesis , Masters , MCur
- Identifier: vital:10059 , http://hdl.handle.net/10948/d1020046
- Description: Implementation strategies for the use of clinical practice guidelines are an integral component in bridging the gap between the best research evidence and clinical practice. However, despite some remarkable investments in health research regarding clinical practice guidelines implementation strategies, it is not yet known which of these are the most effective for intensive care units. The purpose of this research study was to systematically identify and /or search, appraise, extract and synthesize the best available evidence for clinical practice guidelines implementation strategies in intensive care units, in order to develop a draft guideline for clinical practice guidelines implementation strategies in the intensive care units. A systematic review design was used to systematically identify and /or search, appraise, extract and synthesize the best available evidence from the eligible included Level 2 studies (randomized controlled trials and quasi-experimental studies). Level 2 studies were applicable because they present robust evidence in the research results regarding effectiveness of clinical practice guideline implementation strategies. Furthermore, although other systematic reviews conducted in this area before, they included studies of In addition, no systematic review was identified that reviewed Level 2 studies and developed a guideline for clinical practice guideline implementation strategies in the intensive care units. Hence, including only Level 2 studies was distinctive to this research study. Databases searched included: CINAHL with full text, Google Scholar, Academic search complete, Cochrane Register for Randomized Controlled Trials Issue 8 of 12, August 2013, and MEDLINE via PUBMED. Hand search in bound journals was also done. The search strategy identified 315 potentially relevant studies. After the process of critical appraisal, thirteen Level 2 studies were identified as relevant for the review. Of the 13 relevant studies, 10 were randomized controlled trials and three were quasi experimental studies. After the critical appraisal ten RCTs were included in the systematic review. Three studies (quasi-experimental) were excluded on the basis of methodological quality after the critical appraisal and agreement by the two independent reviewers. The Joanna Briggs Institute Critical Appraisal MASTARI Instrument for Randomized Controlled trials/ Experimental studies, and The Joanna Briggs Institute data extraction tools were used to critically appraise, and extract data from the ten included randomized controlled trials. The two reviewers who performed the critical appraisal were qualified critical care professional nurses and experts in research methodology. These reviewers conducted the critical appraisal independently to ensure the objectivity of the process. Appropriate ethical considerations were maintained throughout the process of the research study. The results indicated that 80 percent of the included studies were conducted in adult intensive care units while 20 percent were conducted in the neonatal intensive care units. Furthermore, 60 percent of the studies were conducted in the United States of America, 10 percent in France, a further 10 percent in Taiwan, another 10 percent in England and yet another 10 percfent was conducted in Australia and Newzealand. The included studies utilized more than one (multifaceted) implementation strategies to implement clinical practice guidelines in the intensive care units. The first most utilized were: printed educational materials; Information/ educational sessions/meetings; audit and feedback and champion/local opinion leaders; seconded by educational outreach visits; and computer or internet usage. Third most used were active/passive reminders; systems support; academic detailing/ one-on-one sessions teleconferences/videoconferences and workshops/in services. Fourth most used were ollaboration/interdisciplinary teams; slide shows, teleconferences/videoconferences and discussions. Fifth most used were practical training; monitoring visits and grand rounds. However all the strategies were of equal importance. Conclusively, the included studies utilized multifaceted implementation strategies. However, no study indicated the use of a guideline for the implementation strategies in the process of clinical practice guidelines implementation. The systematic review developed a draft guideline for clinical practice guideline implementation strategies in the intensive care units. The guideline will enhance effective implementation of clinical practice guidelines in such a complex environment.
- Full Text:
- Date Issued: 2014
Strategy execution in a manufacturing facility in the Nelson Mandela Bay
- Authors: Butler, Charles Ted
- Date: 2014
- Subjects: Business planning -- South Africa -- Nelson Mandela Bay Municipality , Manufacturing industries -- South Africa -- Nelson Mandela Bay Municipality
- Language: English
- Type: Thesis , Masters , MBA
- Identifier: vital:8843 , http://hdl.handle.net/10948/d1020075
- Description: The most basic role of operations is to execute a strategy (Pycraft, Singh, Phihlela, Slack, Chambers & Johnston, 2010). The aim of this study is to make a contribution to operational performance by analysing the effectiveness of strategy execution at a confectionery manufacturing facility situated in the Nelson Mandela Bay (NMB). The primary objective of the study is to improve strategy execution at this manufacturing facility by investigating the influence of strategy; business processes; organisational factors; human resources; macro factors and leadership toward the success of strategy execution. The researcher gave consideration to whether this manufacturing facility measured on a strategy grid, is in a professional (champions’) league, headed towards a spectacular success; or headed towards being relegated and failure; or will it achieve somewhere in between like playing in the amateur (first division). The study was conducted in the quantitative paradigm. Data was collected using a structured questionnaire and sourced instruments were used to measure the variables in the hypothesised model. The objective of the questionnaire was to analyse the respondent’s understanding of how strategy is executed, thereby identifying the possible areas that need to be improved. It was found that most managers disagreed that the business processes, organisational factors and human resources effectively support the execution of the operational strategy and that the average response from the managers were neutral in respect of effectiveness of strategy and leadership. The inference is that although this manufacturing facility has a fair strategy, execution thereof is below average. The researcher therefore deduced that the most appropriate section for the manufacturing facility is between the first division and relegation. The research findings indicate that the management team is not effectively executing the operational strategy. The management implication of this finding translates into lost opportunities. These lost opportunities probably contributed to the poor results reported by the plant director in his quarterly performance review. The empirical results are discussed and recommendations are proposed to improve strategy execution, complementing the manufacturing facility’s goals to deliver the best performance and ultimately realise their stated vision: “to be the best and most loved confectionary site in the world”.
- Full Text:
- Date Issued: 2014
- Authors: Butler, Charles Ted
- Date: 2014
- Subjects: Business planning -- South Africa -- Nelson Mandela Bay Municipality , Manufacturing industries -- South Africa -- Nelson Mandela Bay Municipality
- Language: English
- Type: Thesis , Masters , MBA
- Identifier: vital:8843 , http://hdl.handle.net/10948/d1020075
- Description: The most basic role of operations is to execute a strategy (Pycraft, Singh, Phihlela, Slack, Chambers & Johnston, 2010). The aim of this study is to make a contribution to operational performance by analysing the effectiveness of strategy execution at a confectionery manufacturing facility situated in the Nelson Mandela Bay (NMB). The primary objective of the study is to improve strategy execution at this manufacturing facility by investigating the influence of strategy; business processes; organisational factors; human resources; macro factors and leadership toward the success of strategy execution. The researcher gave consideration to whether this manufacturing facility measured on a strategy grid, is in a professional (champions’) league, headed towards a spectacular success; or headed towards being relegated and failure; or will it achieve somewhere in between like playing in the amateur (first division). The study was conducted in the quantitative paradigm. Data was collected using a structured questionnaire and sourced instruments were used to measure the variables in the hypothesised model. The objective of the questionnaire was to analyse the respondent’s understanding of how strategy is executed, thereby identifying the possible areas that need to be improved. It was found that most managers disagreed that the business processes, organisational factors and human resources effectively support the execution of the operational strategy and that the average response from the managers were neutral in respect of effectiveness of strategy and leadership. The inference is that although this manufacturing facility has a fair strategy, execution thereof is below average. The researcher therefore deduced that the most appropriate section for the manufacturing facility is between the first division and relegation. The research findings indicate that the management team is not effectively executing the operational strategy. The management implication of this finding translates into lost opportunities. These lost opportunities probably contributed to the poor results reported by the plant director in his quarterly performance review. The empirical results are discussed and recommendations are proposed to improve strategy execution, complementing the manufacturing facility’s goals to deliver the best performance and ultimately realise their stated vision: “to be the best and most loved confectionary site in the world”.
- Full Text:
- Date Issued: 2014
Stratigraphy and sedimentology of the Mzamba formation in the Eastern Cape, South Africa
- Authors: Susela, Zamampondo
- Date: 2014
- Language: English
- Type: Thesis , Masters , MSc (Geology)
- Identifier: vital:11529 , http://hdl.handle.net/10353/d1019807
- Description: This research project is aimed at providing new information to the stratigraphy, sedimentology, palaeontology and diagenesis of the Mzamba Formation. The study area is located at the south of Port Edward, Eastern Cape. The methodologies employed in this study include field geological investigation and sampling, stratigraphic measurement and logging, thin-section microscope study, powder samples of XRD analysis, and SEM-EDX analysis of rock textures and mineral compositions. The stratigraphy of the Mzamba Formation can be divided into three newly established members, i.e. the Lower Conglomerate Member, Middle Silt/Mudstone-Shell Bed Member and Upper Mudstone-Shell Bed Member with a total thickness of 31.26m in an inland borehole and 30.05m in the field measurement. The Lower Conglomerate Member is 2.65m thick and consists of pebbly conglomerate with coarse sandstone, shell fragments and silicified wood trunks, representing shallow marine nearshore deposits. The Middle Silt/Mudstone and Shell Bed Member is 9.5 m thick and consists of black mudstone and fine-grained siltstone alternated with medium grained pecten beds, which was deposited in a storm influenced deeper marine environment. The Upper Mudstone-Shell Bed Member is 17.9m thick and is made up of fine-mudstones with articulated pecten layers which were deposited in a deep and quiet marine environment. Petrology studies showed that the Mzamba Formation consists of mixed sediments of carbonate and siliciclastic rocks. Siliciclastic rocks include pebbly conglomerates, medium to coarse sandstones and fine-grained mudstones, whereas carbonate rocks include packstone, wackstone and grainstone (pecten beds). The formation shows cyclical pattern of a series fining-upward cyclicities, changing from bottom conglomerate to sandstone, then upward repeated series of cyclotherms from pecten bed to mudstone. Mineralogy of the Mzamba Formation consists of terrigenous minerals of quartz, orthoclase, plagioclase, muscovite and various igneous and metamorphic rock-lithics, clay minerals of smectite, illite and sericite, and carbonate minerals of calcite and dolomite; with minor diagenetic minerals of pyrite, glauconite, hematite, gypsum, albite and organic maceral of vitrinite. Heavy minerals of garnet, zircon and rutile are minor minerals in the strata, which were detrital in origin. Mzamba Formation is a fossiliferous sequence, and contains both fauna and flora fossils in the strata. The pecten beds host well-preserved bivalve, gastropod, brachiopoda, ammonite, and echinoderm; whereas trace fossils of coprolites, burrows and tracks, as well as plant fossils of silicified wood trunks were also found in the formation. Some new fossil species were collected and studied, which include Bivalve: Pteriaceae, Pinnacea and Ostreacea; Gastropod: Cerithiacea and Mesogastopoda; Echinoderm: Echinocystoidea and Crinoidea. The benthonic species predominate in the lower part in the succession, whilst the planktonic species are abundant in the upper part of the sequence, which points to increase in water depths of the depositional environment. Based on lithology, sedimentary structures, and stratum architecture, seven different facies have been distinguished. Facies A (Flat bedded pebbly conglomerate), Facie B (Cross-bedded coarse calcareous sandstone facies), Facies C (Burrowed sandstone facies), Facies D (Shell-fragmental fine-grained calcareous sandstone facies), Facies E (Horizontal bedded calcareous mudstone facies), Facies F (Calcareous patch reef), Facies G (Wash out reef facies). Wash out reef facies is rich in algae, bivalve shells, broken oysters, coral fragments and small pebbles. Four types of cements were found in the Mzamba Formation, including calcite, smectite, illite and quartz. Calcite cement can be further classified into two types, micrite calcite cement and sparite calcite cement. The clay cement consists of smectite and illite and mainly occurs as matrix. The isopachous rim calcite and bright isopachous rim of silica cements indicate diagenesis in a marine phreatic zone. Authigenic minerals which formed in early diagenetic stage include quartz, plagioclase, glauconite and organic maceral of vitrinite. Three stages of diagenesis have been recognised in the sequence, i.e. syndiagenesis, early and late diagenesis. Glauconite pellets and worm faecal pellets were formed in syndiagenetic stage; cementation and authigenic minerals were formed in early diagenetic stage; whereas clay mineral conversion of smectite to illite, quartz overgrowth, bioclast recrystallization and calcite replacement took place during late diagenetic stage. The pebbly conglomerate at the bottom of the Mzamba Formation represents high energy deposits in a shallow marine environment; the grain-size gradually becomes finer in the middle succession and finest mudstone facies at the top of the succession, which represents deep marine deposits. Meanwhile, benthonic fossils are dominant in the bottom succession while plankton fossils are more abundant in the top succession. These features indicate that the Mzamba Formation constitutes a perfect transgression sequence, and the depositional environments started from shallow marine near shore environment, and gradually shifted to a deep marine quiet water environment.
- Full Text:
- Date Issued: 2014
- Authors: Susela, Zamampondo
- Date: 2014
- Language: English
- Type: Thesis , Masters , MSc (Geology)
- Identifier: vital:11529 , http://hdl.handle.net/10353/d1019807
- Description: This research project is aimed at providing new information to the stratigraphy, sedimentology, palaeontology and diagenesis of the Mzamba Formation. The study area is located at the south of Port Edward, Eastern Cape. The methodologies employed in this study include field geological investigation and sampling, stratigraphic measurement and logging, thin-section microscope study, powder samples of XRD analysis, and SEM-EDX analysis of rock textures and mineral compositions. The stratigraphy of the Mzamba Formation can be divided into three newly established members, i.e. the Lower Conglomerate Member, Middle Silt/Mudstone-Shell Bed Member and Upper Mudstone-Shell Bed Member with a total thickness of 31.26m in an inland borehole and 30.05m in the field measurement. The Lower Conglomerate Member is 2.65m thick and consists of pebbly conglomerate with coarse sandstone, shell fragments and silicified wood trunks, representing shallow marine nearshore deposits. The Middle Silt/Mudstone and Shell Bed Member is 9.5 m thick and consists of black mudstone and fine-grained siltstone alternated with medium grained pecten beds, which was deposited in a storm influenced deeper marine environment. The Upper Mudstone-Shell Bed Member is 17.9m thick and is made up of fine-mudstones with articulated pecten layers which were deposited in a deep and quiet marine environment. Petrology studies showed that the Mzamba Formation consists of mixed sediments of carbonate and siliciclastic rocks. Siliciclastic rocks include pebbly conglomerates, medium to coarse sandstones and fine-grained mudstones, whereas carbonate rocks include packstone, wackstone and grainstone (pecten beds). The formation shows cyclical pattern of a series fining-upward cyclicities, changing from bottom conglomerate to sandstone, then upward repeated series of cyclotherms from pecten bed to mudstone. Mineralogy of the Mzamba Formation consists of terrigenous minerals of quartz, orthoclase, plagioclase, muscovite and various igneous and metamorphic rock-lithics, clay minerals of smectite, illite and sericite, and carbonate minerals of calcite and dolomite; with minor diagenetic minerals of pyrite, glauconite, hematite, gypsum, albite and organic maceral of vitrinite. Heavy minerals of garnet, zircon and rutile are minor minerals in the strata, which were detrital in origin. Mzamba Formation is a fossiliferous sequence, and contains both fauna and flora fossils in the strata. The pecten beds host well-preserved bivalve, gastropod, brachiopoda, ammonite, and echinoderm; whereas trace fossils of coprolites, burrows and tracks, as well as plant fossils of silicified wood trunks were also found in the formation. Some new fossil species were collected and studied, which include Bivalve: Pteriaceae, Pinnacea and Ostreacea; Gastropod: Cerithiacea and Mesogastopoda; Echinoderm: Echinocystoidea and Crinoidea. The benthonic species predominate in the lower part in the succession, whilst the planktonic species are abundant in the upper part of the sequence, which points to increase in water depths of the depositional environment. Based on lithology, sedimentary structures, and stratum architecture, seven different facies have been distinguished. Facies A (Flat bedded pebbly conglomerate), Facie B (Cross-bedded coarse calcareous sandstone facies), Facies C (Burrowed sandstone facies), Facies D (Shell-fragmental fine-grained calcareous sandstone facies), Facies E (Horizontal bedded calcareous mudstone facies), Facies F (Calcareous patch reef), Facies G (Wash out reef facies). Wash out reef facies is rich in algae, bivalve shells, broken oysters, coral fragments and small pebbles. Four types of cements were found in the Mzamba Formation, including calcite, smectite, illite and quartz. Calcite cement can be further classified into two types, micrite calcite cement and sparite calcite cement. The clay cement consists of smectite and illite and mainly occurs as matrix. The isopachous rim calcite and bright isopachous rim of silica cements indicate diagenesis in a marine phreatic zone. Authigenic minerals which formed in early diagenetic stage include quartz, plagioclase, glauconite and organic maceral of vitrinite. Three stages of diagenesis have been recognised in the sequence, i.e. syndiagenesis, early and late diagenesis. Glauconite pellets and worm faecal pellets were formed in syndiagenetic stage; cementation and authigenic minerals were formed in early diagenetic stage; whereas clay mineral conversion of smectite to illite, quartz overgrowth, bioclast recrystallization and calcite replacement took place during late diagenetic stage. The pebbly conglomerate at the bottom of the Mzamba Formation represents high energy deposits in a shallow marine environment; the grain-size gradually becomes finer in the middle succession and finest mudstone facies at the top of the succession, which represents deep marine deposits. Meanwhile, benthonic fossils are dominant in the bottom succession while plankton fossils are more abundant in the top succession. These features indicate that the Mzamba Formation constitutes a perfect transgression sequence, and the depositional environments started from shallow marine near shore environment, and gradually shifted to a deep marine quiet water environment.
- Full Text:
- Date Issued: 2014
Stratigraphy, sedimentary facies and diagenesis of the ECCA group, Karoo supergroup in the Eastern Cape, South Africa
- Authors: Nyathi, Nonhlanhla
- Date: 2014
- Language: English
- Type: Thesis , Masters , MSc (Geology)
- Identifier: vital:11528 , http://hdl.handle.net/10353/d1019776
- Description: This is a MSc research project, and is aimed at the new insight on the stratigraphy, sedimentary facies, diagenesis and depositional environments of the Ecca Group, Karoo Supergroup in the Eastern Cape Province. Methodologies used in this research include field investigation, stratigraphic logging, thin-section microscope study, X-Ray Diffraction (XRD) and Scanning Electron Microscopy (SEM) analyses. The stratigraphy of the Ecca Group is divided into five formations, namely the Prince Albert Formation, Whitehill Formation, Collingham Formation, Rippon Formation and the Fort Brown Formation from bottom upward. Based on the field investigation and laboratory correlation, the Prince Albert, Whitehill, Collingham, and Fort Brown Formations can each be subdivided into two new members, i.e. lower member and upper member; whereas three new members have been proposed for the Rippon Formation, i.e. lower, middle and upper members. The Ecca Group sediments were accumulated in various depositional environments, from bottom of deep marine environment, passed through the middle of deltaic environment, and ended in a lacustrine environment. The Prince Albert Formation, Whitehill Formation and the Collingham Formation were all deposited in a deep marine basin, whilst the Rippon Formation was laid down in a deltaic environment. As the climate gradually became warmer and drier, the top Fort Brown Formation was lastly deposited in a lacustrine environment. The stratigraphic succession of the Ecca Group constitutes a perfect regression sequence, indicating that the marine water gradually retreated and the sea-level gradually dropped. The rocks in the Ecca Group are mainly terrigenous sandstone and mudstone with some coarse grain-sized siliciclastic rock of conglomerate. The sandstones are dominated by feldspathic graywackes with minor quartz-wackes, and there are no arenites in the Ecca Group. Whereas the mudstones are dominated by grayish mudrocks and black shales, purer claystone was found in the turbidite facies of the Collingham Formation, which probably has economic significance for the future since the reserve is quite large. Optical microscope, XRD and SEM analyses demonstrated that the minerals in the Ecca Group include detrital minerals of quartz, orthoclase, microcline, plagioclase, biotite, muscovite; and clay minerals (smectite, kaolinite, illite and sericite). These minerals constitute the rock framework grains and cements whereas; the authigenic minerals of calcite and hematite were formed during diagenesis. Accessory minerals such as rutile and zircon are the heavy minerals present in the strata, and occur only in a small amount. Based on the lithologies, sedimentary structures and sequence stacking patterns, ten sedimentary facies have been recognised, namely 1) Grayish laminated and thin bedded shale facies, 2) Grayish laminated shale and intercalated chert facies, 3) Grayish rhythmite facies (all the three facies above were deposited in deep marine water); 4) Flat and lenticular bedded graywacke facies, 5) Grayish alternating mudstone and sandstone facies, 6) Dark organic rich mudstone facies, 7) Fossil bearing mudstone facies, 8) Laminated and thin bedded black mudstone with lenticular siltstone facies, 9) Interbedded grayish sandstone and mudstone facies (above Facies 4-9 were deposited in deltaic environment and appeared in the Rippon Formation); and 10) Varved rhythmic mudstone facies, which occurs only in the Fort Brown Formation and represents lacustrine sediments. Four types of cements have been identified in the rocks of the Ecca Group, including quartz, smectite, calcite and feldspar cements. The first three cement types are the major cement types, whilst the feldspar cement is minor and occurs only locally. Recrystallisation in Ecca sediments includes quartz, feldspar, clay mineral recrystallisation and conversion from smectite and kaolinite to illite and then to sericite. Replacement involves calcite replacing quartz, feldspar and clay matrix; accompanied by albitization, i.e. albite replacing other feldspar minerals in a deep burial environment. Dissolution in the Ecca Group involved calcite and kaolinite dissolving and leaching, which created more pore-space and increased porosity. The sediments of the Ecca Group went through three stages of digenesis, namely the early stage, the late stage and the up lift stage which led the rocks being exposed on the Earth’s surface and being weathered. In each stage, some minerals became unstable, then replaced by a more stable mineral suitable for the new diagenetic environment. Precipitation of cements and formation of authigenic minerals mostly occurred in the early diagenetic stage, which led the soft sediments becoming a hard rock; whilst recrystallisation, replacement, and dissolution took place mostly in the later diageneti
- Full Text:
- Date Issued: 2014
- Authors: Nyathi, Nonhlanhla
- Date: 2014
- Language: English
- Type: Thesis , Masters , MSc (Geology)
- Identifier: vital:11528 , http://hdl.handle.net/10353/d1019776
- Description: This is a MSc research project, and is aimed at the new insight on the stratigraphy, sedimentary facies, diagenesis and depositional environments of the Ecca Group, Karoo Supergroup in the Eastern Cape Province. Methodologies used in this research include field investigation, stratigraphic logging, thin-section microscope study, X-Ray Diffraction (XRD) and Scanning Electron Microscopy (SEM) analyses. The stratigraphy of the Ecca Group is divided into five formations, namely the Prince Albert Formation, Whitehill Formation, Collingham Formation, Rippon Formation and the Fort Brown Formation from bottom upward. Based on the field investigation and laboratory correlation, the Prince Albert, Whitehill, Collingham, and Fort Brown Formations can each be subdivided into two new members, i.e. lower member and upper member; whereas three new members have been proposed for the Rippon Formation, i.e. lower, middle and upper members. The Ecca Group sediments were accumulated in various depositional environments, from bottom of deep marine environment, passed through the middle of deltaic environment, and ended in a lacustrine environment. The Prince Albert Formation, Whitehill Formation and the Collingham Formation were all deposited in a deep marine basin, whilst the Rippon Formation was laid down in a deltaic environment. As the climate gradually became warmer and drier, the top Fort Brown Formation was lastly deposited in a lacustrine environment. The stratigraphic succession of the Ecca Group constitutes a perfect regression sequence, indicating that the marine water gradually retreated and the sea-level gradually dropped. The rocks in the Ecca Group are mainly terrigenous sandstone and mudstone with some coarse grain-sized siliciclastic rock of conglomerate. The sandstones are dominated by feldspathic graywackes with minor quartz-wackes, and there are no arenites in the Ecca Group. Whereas the mudstones are dominated by grayish mudrocks and black shales, purer claystone was found in the turbidite facies of the Collingham Formation, which probably has economic significance for the future since the reserve is quite large. Optical microscope, XRD and SEM analyses demonstrated that the minerals in the Ecca Group include detrital minerals of quartz, orthoclase, microcline, plagioclase, biotite, muscovite; and clay minerals (smectite, kaolinite, illite and sericite). These minerals constitute the rock framework grains and cements whereas; the authigenic minerals of calcite and hematite were formed during diagenesis. Accessory minerals such as rutile and zircon are the heavy minerals present in the strata, and occur only in a small amount. Based on the lithologies, sedimentary structures and sequence stacking patterns, ten sedimentary facies have been recognised, namely 1) Grayish laminated and thin bedded shale facies, 2) Grayish laminated shale and intercalated chert facies, 3) Grayish rhythmite facies (all the three facies above were deposited in deep marine water); 4) Flat and lenticular bedded graywacke facies, 5) Grayish alternating mudstone and sandstone facies, 6) Dark organic rich mudstone facies, 7) Fossil bearing mudstone facies, 8) Laminated and thin bedded black mudstone with lenticular siltstone facies, 9) Interbedded grayish sandstone and mudstone facies (above Facies 4-9 were deposited in deltaic environment and appeared in the Rippon Formation); and 10) Varved rhythmic mudstone facies, which occurs only in the Fort Brown Formation and represents lacustrine sediments. Four types of cements have been identified in the rocks of the Ecca Group, including quartz, smectite, calcite and feldspar cements. The first three cement types are the major cement types, whilst the feldspar cement is minor and occurs only locally. Recrystallisation in Ecca sediments includes quartz, feldspar, clay mineral recrystallisation and conversion from smectite and kaolinite to illite and then to sericite. Replacement involves calcite replacing quartz, feldspar and clay matrix; accompanied by albitization, i.e. albite replacing other feldspar minerals in a deep burial environment. Dissolution in the Ecca Group involved calcite and kaolinite dissolving and leaching, which created more pore-space and increased porosity. The sediments of the Ecca Group went through three stages of digenesis, namely the early stage, the late stage and the up lift stage which led the rocks being exposed on the Earth’s surface and being weathered. In each stage, some minerals became unstable, then replaced by a more stable mineral suitable for the new diagenetic environment. Precipitation of cements and formation of authigenic minerals mostly occurred in the early diagenetic stage, which led the soft sediments becoming a hard rock; whilst recrystallisation, replacement, and dissolution took place mostly in the later diageneti
- Full Text:
- Date Issued: 2014
Strength training and cardiovascular risk post-menses, with particular emphasis on the plasma lipoproteins: a controlled trial
- Authors: Viljoen, Janet Erica
- Date: 2014
- Subjects: Weight training for women -- Physiological aspects , Exercise for women -- Physiological aspects , Middle-aged women -- Health and hygiene , Cardiovascular system -- Diseases , Hypercholesteremia , Blood lipoproteins
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5155 , http://hdl.handle.net/10962/d1013578
- Description: Introduction: Cardiovascular disease affects a greater proportion of females than it does males, and is responsible for an estimated 52 percent of female deaths per annum, globally. Due to the loss of oestrogen associated with the menopause, post-menopausal females are at elevated risk for hypercholesterolaemia which is a primary risk factor for cardiovascular disease. It has not yet been conclusively established whether resistance training can be used to ameliorate hypercholesterolaemia. Aim: This randomized controlled trial investigated what effect 12 weeks of progressive resistance training would have on plasma lipoproteins in a sample of post-menopausal females. Methods: Caucasian women (n=30 intervention and n=18 control) between the ages of 55 and 65 years who were not taking hormone replacement therapy were recruited. Participants did not smoke, were sedentary, were not taking any form of cholesterol-lowering medication, had at least one cholesterol abnormality at baseline but were otherwise healthy and able to participate in a strength training programme. Following extensive medical pre-screening, information dissemination and voluntary consent, the sample was divided into two groups. The exercise sample undertook 12 weeks of resistance training on five days of the week. The control group received no intervention. Measurements were obtained at baseline and every four weeks thereafter and included measures of strength, biochemistry (oestradiol, testosterone, full blood lipid profile, glycated haemoglobin and sex hormone binding globulin), anthropometry, morphology and self-reports (dietary intake, energy expenditure and the profile of mood states questionnaire). Results: There was no change to low density lipoprotein cholesterol, high density lipoprotein cholesterol, triglyceride content or total cholesterol as a result of the intervention. Back, chest and leg strength increased significantly (p<0.01) (increases of 51 percent, 35 percent and 43 percent respectively from baseline); waist circumference dropped (p<0.01) by 5 percent overall and diastolic blood pressure decreased significantly (-9 percent, p<0.01) in the exercise cohort but no change was noted in the matched control. Dietary intake, energy expenditure and body mass remained unchanged in both samples. Morphology (sum of skinfolds, estimated body fat content and girth measures) did not change and nor did other biochemical measures (HbA1c and sex hormone binding globulin) or hormone levels (oestradiol and testosterone). Despite the lack of overall change, an important finding was noted in individual results where a clear indication of ‘responders’ and ‘non-responders’ emerged. Conclusion: Overall mean results suggest that 12 weeks resistance training undertaken five days of the week was ineffective in reducing hypercholesterolaemia in this sample. Despite there being no identifying characteristics determined in this sample, evidence of responders and non-responders to the intervention indicates that reliance on mean data may not be sufficient when analysing data from exercise interventions. Therefore, while progressive resistance training had a positive effect on strength, waist circumference and diastolic blood pressure, it did not positively influence the plasma lipoproteins in this cohort of post-menopausal women. , Maiden name: Kelly, Janet Erica
- Full Text:
- Date Issued: 2014
- Authors: Viljoen, Janet Erica
- Date: 2014
- Subjects: Weight training for women -- Physiological aspects , Exercise for women -- Physiological aspects , Middle-aged women -- Health and hygiene , Cardiovascular system -- Diseases , Hypercholesteremia , Blood lipoproteins
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5155 , http://hdl.handle.net/10962/d1013578
- Description: Introduction: Cardiovascular disease affects a greater proportion of females than it does males, and is responsible for an estimated 52 percent of female deaths per annum, globally. Due to the loss of oestrogen associated with the menopause, post-menopausal females are at elevated risk for hypercholesterolaemia which is a primary risk factor for cardiovascular disease. It has not yet been conclusively established whether resistance training can be used to ameliorate hypercholesterolaemia. Aim: This randomized controlled trial investigated what effect 12 weeks of progressive resistance training would have on plasma lipoproteins in a sample of post-menopausal females. Methods: Caucasian women (n=30 intervention and n=18 control) between the ages of 55 and 65 years who were not taking hormone replacement therapy were recruited. Participants did not smoke, were sedentary, were not taking any form of cholesterol-lowering medication, had at least one cholesterol abnormality at baseline but were otherwise healthy and able to participate in a strength training programme. Following extensive medical pre-screening, information dissemination and voluntary consent, the sample was divided into two groups. The exercise sample undertook 12 weeks of resistance training on five days of the week. The control group received no intervention. Measurements were obtained at baseline and every four weeks thereafter and included measures of strength, biochemistry (oestradiol, testosterone, full blood lipid profile, glycated haemoglobin and sex hormone binding globulin), anthropometry, morphology and self-reports (dietary intake, energy expenditure and the profile of mood states questionnaire). Results: There was no change to low density lipoprotein cholesterol, high density lipoprotein cholesterol, triglyceride content or total cholesterol as a result of the intervention. Back, chest and leg strength increased significantly (p<0.01) (increases of 51 percent, 35 percent and 43 percent respectively from baseline); waist circumference dropped (p<0.01) by 5 percent overall and diastolic blood pressure decreased significantly (-9 percent, p<0.01) in the exercise cohort but no change was noted in the matched control. Dietary intake, energy expenditure and body mass remained unchanged in both samples. Morphology (sum of skinfolds, estimated body fat content and girth measures) did not change and nor did other biochemical measures (HbA1c and sex hormone binding globulin) or hormone levels (oestradiol and testosterone). Despite the lack of overall change, an important finding was noted in individual results where a clear indication of ‘responders’ and ‘non-responders’ emerged. Conclusion: Overall mean results suggest that 12 weeks resistance training undertaken five days of the week was ineffective in reducing hypercholesterolaemia in this sample. Despite there being no identifying characteristics determined in this sample, evidence of responders and non-responders to the intervention indicates that reliance on mean data may not be sufficient when analysing data from exercise interventions. Therefore, while progressive resistance training had a positive effect on strength, waist circumference and diastolic blood pressure, it did not positively influence the plasma lipoproteins in this cohort of post-menopausal women. , Maiden name: Kelly, Janet Erica
- Full Text:
- Date Issued: 2014
Structural bioinformatics analysis of the Hsp40 and Hsp70 molecular chaperones from humans
- Authors: Adeyemi, Samson Adebowale
- Date: 2014
- Subjects: Structural bioinformatics , Molecular chaperones , Heat shock proteins , Protein-protein interactions , Biomolecules
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4171 , http://hdl.handle.net/10962/d1020962
- Description: HSP70 is one of the most important families of molecular chaperone that regulate the folding and transport of client proteins in an ATP dependent manner. The ATPase activity of HSP70 is stimulated through an interaction with its family of HSP40 co-chaperones. There is evidence to suggest that specific partnerships occur between the different HSP40 and HSP70 isoforms. While some of the residues involved in the interaction are known, many of the residues governing the specificity of HSP40-HSP70 partnerships are not precisely defined. It is not currently possible to predict which HSP40 and HSP70 isoforms will interact. We attempted to use bioinformatics to identify residues involved in the specificity of the interaction between the J domain from HSP40 and the ATPase domain from the HSP70 isoforms from humans. A total of 49 HSP40 and 13 HSP70 sequences from humans were retrieved and used for subsequent analyses. The HSP40 J domains and HSP70 ATPase domains were extracted using python scripts and classified according to the subcellular localization of the proteins using localization prediction programs. Motif analysis was carried out using the full length HSP40 proteins and Multiple Sequence Alignment (MSA) was performed to identify conserved residues that may contribute to the J domain – ATPase domain interactions. Phylogenetic inference of the proteins was also performed in order to study their evolutionary relationship. Homology models of the J domains and ATPase domains were generated. The corresponding models were docked using HADDOCK server in order to analyze possible putative interactions between the partner proteins using the Protein Interactions Calculator (PIC). The level of residue conservation was found to be higher in Type I and II HSP40 than in Type III J proteins. While highly conserved residues on helixes II and III could play critical roles in J domain interactions with corresponding HSP70s, conserved residues on helixes I and IV seemed to be significant in keeping the J domain in its right orientation for functional interactions with HSP70s. Our results also showed that helixes II and III formed the interaction interface for binding to HSP70 ATPase domain as well as the linker residues. Finally, data based docking procedures, such as applied in this study, could be an effective method to investigate protein-protein interactions complex of biomolecules.
- Full Text:
- Date Issued: 2014
- Authors: Adeyemi, Samson Adebowale
- Date: 2014
- Subjects: Structural bioinformatics , Molecular chaperones , Heat shock proteins , Protein-protein interactions , Biomolecules
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4171 , http://hdl.handle.net/10962/d1020962
- Description: HSP70 is one of the most important families of molecular chaperone that regulate the folding and transport of client proteins in an ATP dependent manner. The ATPase activity of HSP70 is stimulated through an interaction with its family of HSP40 co-chaperones. There is evidence to suggest that specific partnerships occur between the different HSP40 and HSP70 isoforms. While some of the residues involved in the interaction are known, many of the residues governing the specificity of HSP40-HSP70 partnerships are not precisely defined. It is not currently possible to predict which HSP40 and HSP70 isoforms will interact. We attempted to use bioinformatics to identify residues involved in the specificity of the interaction between the J domain from HSP40 and the ATPase domain from the HSP70 isoforms from humans. A total of 49 HSP40 and 13 HSP70 sequences from humans were retrieved and used for subsequent analyses. The HSP40 J domains and HSP70 ATPase domains were extracted using python scripts and classified according to the subcellular localization of the proteins using localization prediction programs. Motif analysis was carried out using the full length HSP40 proteins and Multiple Sequence Alignment (MSA) was performed to identify conserved residues that may contribute to the J domain – ATPase domain interactions. Phylogenetic inference of the proteins was also performed in order to study their evolutionary relationship. Homology models of the J domains and ATPase domains were generated. The corresponding models were docked using HADDOCK server in order to analyze possible putative interactions between the partner proteins using the Protein Interactions Calculator (PIC). The level of residue conservation was found to be higher in Type I and II HSP40 than in Type III J proteins. While highly conserved residues on helixes II and III could play critical roles in J domain interactions with corresponding HSP70s, conserved residues on helixes I and IV seemed to be significant in keeping the J domain in its right orientation for functional interactions with HSP70s. Our results also showed that helixes II and III formed the interaction interface for binding to HSP70 ATPase domain as well as the linker residues. Finally, data based docking procedures, such as applied in this study, could be an effective method to investigate protein-protein interactions complex of biomolecules.
- Full Text:
- Date Issued: 2014
Structural, optical and electrical characterization of nano-sized c-tio2 quamtum dots synthesized by spray pyrolysis
- Authors: Taziwa, Raymond Tichaona
- Date: 2014
- Language: English
- Type: Thesis , Doctoral , PhD (Chemistry)
- Identifier: vital:11342 , http://hdl.handle.net/10353/d1016089
- Description: In the 21st century, scientific communities face challenges and opportunities concerning future development, where innovations must be a key driver over the past, evolution of African societies were based on incomplete models, only taking into account economical growth and not paying attention to environmental deterioration as a consequence of anthropogenic activity and environmental pollution. We have to learn from our past mistakes in order not to repeat them. Education and research of today as the embryonic stages of the development models of tomorrow should be directed toward a sustainable mentality. In this sense, solar energy technologies have emerged as key instruments for minimizing environmental impact as well as reducing economic cost in the field of renewable energies. Titanium dioxide is a fascinating low cost material exhibiting unique properties of stability and photo catalytic activities, leading to clean technologies in water purification and energy conversion of sunlight. However, conventional techniques (high temperature, high vacuum, high pressures) of processing titanium dioxide are a technological limitation due to excessive energy consumption. This poses a handicap for practical applications in areas such as preparation of hybrid organic/Titanium dioxide materials or devices on thermo flexible substrates such as plastic material. It is for this reason that the investigation presented in this Ph.D thesis deals with the development of spray pyrolysis techniques for preparation of carbon doped titanium dioxide nano powders for solar cell applications. This thesis is therefore structured as follows: Chapter 1 gives a general overview of the work done in this thesis. This work relies greatly on the excellent structural optical and electrical properties of TiO2 thin films, as well as its chemical resistance and insulating properties. A summary of the physical, optical, electrical and chemical properties reported in the literature, with an emphasis on those relevant to solar cell fabrication, is presented in Chapter 2. Chapter 3 gives a concise literature review on models governing droplet formation in ultrasonic spray pyrolysis (USP) techniques, the limitations of these models have been exposed and a new relation model for estimating the final particle size given a set of initial reaction conditions has been proposed. The presently derived model is quite advantageous in that it does not require the investigator to look up values of surface tension and density for every precursor solution. Chapter 4 presents in detail the designed and constructed spray pyrolysis system capable of realizing desired nano structures for photovoltaic applications. The first system employed an ultrasonic atomization spray nozzle in order to create an aerosol of the TiO2 precursor. The reasons for choosing ultrasonic spray deposition (USP) and the TiO2 precursors, titanium iso propoxide and titanium tetra butoxide are discussed. Chapter 5 outlines experimental methodologies used in synthesis and characterization of the materials used in this study. Chapter 5 further provides experimental methodologies used in fabrication of a new type of photo electrochemical solar cells (PECs). Chapter 6 reveals the opto-electrical results of PECs solar cells fabricated. There are numerous properties that are affected by the size but emphasis will be placed on nano-size and confinement effects. Chapter 7 presents a confirmation of the phonon confinement effects in C-TiO2 QDs for the first time. In addition Chapter 7 also presents a new phonon confinement model. Chapter 8 reveals the optical, structural and electronic properties of C-TiO2 QDs synthesized by USP and PSP techniques. In addition the electrical properties of C-TiO2 QDs PEC solar cells devices are reported in Chapter 8. Concluding remarks, with potential future research projects are presented in Chapter 9. Through these 9 chapters, all research questions have been answered satisfactorily and all objectives met. Most of the work contained in this thesis has been subjected to external reviews through publication of these peer reviewed articles.
- Full Text:
- Date Issued: 2014
- Authors: Taziwa, Raymond Tichaona
- Date: 2014
- Language: English
- Type: Thesis , Doctoral , PhD (Chemistry)
- Identifier: vital:11342 , http://hdl.handle.net/10353/d1016089
- Description: In the 21st century, scientific communities face challenges and opportunities concerning future development, where innovations must be a key driver over the past, evolution of African societies were based on incomplete models, only taking into account economical growth and not paying attention to environmental deterioration as a consequence of anthropogenic activity and environmental pollution. We have to learn from our past mistakes in order not to repeat them. Education and research of today as the embryonic stages of the development models of tomorrow should be directed toward a sustainable mentality. In this sense, solar energy technologies have emerged as key instruments for minimizing environmental impact as well as reducing economic cost in the field of renewable energies. Titanium dioxide is a fascinating low cost material exhibiting unique properties of stability and photo catalytic activities, leading to clean technologies in water purification and energy conversion of sunlight. However, conventional techniques (high temperature, high vacuum, high pressures) of processing titanium dioxide are a technological limitation due to excessive energy consumption. This poses a handicap for practical applications in areas such as preparation of hybrid organic/Titanium dioxide materials or devices on thermo flexible substrates such as plastic material. It is for this reason that the investigation presented in this Ph.D thesis deals with the development of spray pyrolysis techniques for preparation of carbon doped titanium dioxide nano powders for solar cell applications. This thesis is therefore structured as follows: Chapter 1 gives a general overview of the work done in this thesis. This work relies greatly on the excellent structural optical and electrical properties of TiO2 thin films, as well as its chemical resistance and insulating properties. A summary of the physical, optical, electrical and chemical properties reported in the literature, with an emphasis on those relevant to solar cell fabrication, is presented in Chapter 2. Chapter 3 gives a concise literature review on models governing droplet formation in ultrasonic spray pyrolysis (USP) techniques, the limitations of these models have been exposed and a new relation model for estimating the final particle size given a set of initial reaction conditions has been proposed. The presently derived model is quite advantageous in that it does not require the investigator to look up values of surface tension and density for every precursor solution. Chapter 4 presents in detail the designed and constructed spray pyrolysis system capable of realizing desired nano structures for photovoltaic applications. The first system employed an ultrasonic atomization spray nozzle in order to create an aerosol of the TiO2 precursor. The reasons for choosing ultrasonic spray deposition (USP) and the TiO2 precursors, titanium iso propoxide and titanium tetra butoxide are discussed. Chapter 5 outlines experimental methodologies used in synthesis and characterization of the materials used in this study. Chapter 5 further provides experimental methodologies used in fabrication of a new type of photo electrochemical solar cells (PECs). Chapter 6 reveals the opto-electrical results of PECs solar cells fabricated. There are numerous properties that are affected by the size but emphasis will be placed on nano-size and confinement effects. Chapter 7 presents a confirmation of the phonon confinement effects in C-TiO2 QDs for the first time. In addition Chapter 7 also presents a new phonon confinement model. Chapter 8 reveals the optical, structural and electronic properties of C-TiO2 QDs synthesized by USP and PSP techniques. In addition the electrical properties of C-TiO2 QDs PEC solar cells devices are reported in Chapter 8. Concluding remarks, with potential future research projects are presented in Chapter 9. Through these 9 chapters, all research questions have been answered satisfactorily and all objectives met. Most of the work contained in this thesis has been subjected to external reviews through publication of these peer reviewed articles.
- Full Text:
- Date Issued: 2014
Studies on the antimicrobial, antioxidant and antiproliferative potential of the ethyl acetate extract and compounds of Peltophorum africanum
- Authors: Okeleye, Benjamin Ifeoluwa
- Date: 2014
- Language: English
- Type: Thesis , Masters , MSc (Microbiology)
- Identifier: vital:11282 , http://hdl.handle.net/10353/d1016165
- Description: Cells are constantly exposed to a variety of oxidizing agents, some of which are necessary for life. Oxidants produced in excess can cause an imbalance, leading to oxidative stress, especially in chronic bacterial, viral, and parasitic infections. This can result to damage of biomolecules such as lipids, proteins, and DNA, hence, an increased risk for cancer. Plants have a long history of use in the treatment of cancer. Plant secondary metabolites have proved to be an excellent reservoir of new medical compounds. Fruits, vegetables, and whole grains contain a wide variety of antioxidant phytochemicals, such as phenolics and carotenoids, and may help protect cellular systems from oxidative damage and also may lower the risk of chronic diseases. Peltophorum africanum, a member of the family Fabaceae (Sond) is also known as the African weeping wattle and is used in traditional medicine in South Africa. This study investigated the antimicrobial, antioxidant and antiproliferative potential of the ethyl acetate extract and compounds of Peltophorum africanum in order to validate its pharmacological use. The study assessed the in vitro antimicrobial activity of ethyl acetate extract (EAE) of Peltophorum africanum stem bark and its fractions by the agar well and macrodilution methods. The toxicity on a normal human liver cell (Chang liver cell) and antiproliferation of human breast (MCF-7), colon (HT-29) and cervical (HeLa) cancer cell lines were determined using the CellTiter-Blue cell viability assay and the mechanism of action delineated using the Nucleic Acid and Protein Purification Nucleospin® Tissue Kit, Scanning Electron Microscopy (SEM), Propidium iodide (PI) and Acridine orange (AO) double-staining techniques, the Cleaved Caspase 3 (Asp 175) Alexa Fluor® 488 Antibody and the Coulter® DNA PrepTM Reagents Kit. Purification and identification of the compounds from EAE and fractions as well as the morphological alteration of bacteria, yeast and cancer cells were determined using thin layer chromatography, infrared spectra fingerprint and GC-MS analysis, micro-dilution and scanning electron microscopy with energy-dispersive X-ray analysis. In vitro antioxidant activity of EAE was determined by means of radical scavenging and ferric reducing power analysis using 2, 2-diphenyl-1-picrylhydrazyl (DPPH), 2, 2`-azino-bis (3-ethylbenzthiazoline-6-sulfonic acid) (ABTS) kit, hydrogen peroxide (H2O2), iron (iii) chloride (Fe3+) and nitric oxide (NO). To assess the likely effects of secondary metabolites on the activities observed; total proanthocyanidins, phenolics, flavonols, and flavonoids were determined using standard phytochemical methods. Data were analyzed by one way analysis of variance (ANOVA; SPSS Version 17.0, 2011), regression analysis (MINITAB, version 12 for windows), probit analysis test (software NCSS, 2007) and GraphPad Prism4 software package. The p-values < 0.05 were considered significant. Marked activity of the extract was observed against Plesiomonas shigelloides ATCC 51903, with MIC and MLC values of 0.15625 and 0.3125mg/mL, respectively. The extract was both bactericidal (MICindex ≤ 2) and bacteriostatic/fungistatic (MICindex > 2) in activity. Lethal dose at 50 (LD50) showed 82.64 ± 1.40 degree of toxicity at 24 hrs, and 95 percentile of cell death dose activity ranged from log 3.12 ± 0.01 to 4.59 ± 0.03. The activity of the eight fractions tested ranged from 1.0 ± 0.5 to 3.7 ± 1.6 mg/mL (IC50) and from 2.1 ± 0.8 to 6.25 ± 0 mg/mL (IC90) (Chapter 3). Due to the effect of compounds present in the crude extract and fractions, the P. aeruginosa treated with EAE had a reduction of sodium from 5.55 % (untreated) - 1.50 %. For C. albicans, pottasium was reduced from 4.16 % (untreated) - 0.76 % (T1). Remarkable morphological alterations were observed including deformation of the germ tubes and perforation of the cell wall (Chapter 4). Extract scavenging activity of 88.73± 6.69 % (25 μg mL-1), 53.93±1.09 % (25 μg mL-1) were recorded for H2O2 and NO respectively with proanthocyanidins (92.18±4.68 mg/g) occurring more (p < 0.05) in the extract compared to all other phenolics compounds (Chapter 5). Significant reduction in cell viability of the cells was noted as the MCF-7 cells were reduced from 100 - 54.33±1.84 % after 72 hrs of treatment with 5 μg/mL of EAE (P. value < 0.05). TEt10 was cytotoxic against human normal cells (chang liver cell) at EC50 of 37 μg/mL and 74 μg/mL after 24 and 48 h of treatment respectively. Marked antiproliferative activity of 13.2 μg/mL (EC50) was observed when HeLa cells were treated for 48 h. Internucleosomal DNA of MCF-7, HT-29 and HeLa cells randomly fragmented into an uninterrupted spectrum of sizes, complemented by the intercalation of nucleic acid-specific fluorochromes by PI and AO spotting two phases of apoptosis; early (EA) and late (LA) apoptosis. Distinctive ultramorphological changes observed include; cell shrinkage, membrane blebbing, and typical cell induced death. The study also recorded 705.102 ± 28.56 % TEt10 caspase-3 activity compared to curcumin 592.857 ± 165.76 % (positive control) and untreated (negative control; 100 ± 15.81 %) cells. Percentage HeLa cell with Sub-G1 DNA phase increased from 0.13 ± 0.06 % (negative control) to 13.8 ± 3.04 % compared to curcumin (8.17 ± 2.20 %) after treatment with TEt10. The compounds identified in the fractions including Colchicine, N-(trifluoroacetyl)methyl-N-deacetyl-, Lupeol and .gamma.-Sitosterol may be responsible for the induction of apoptosis observed and could be further studied in vivo as a potential template for new anticancer treatment (Chapter 6 & 7).
- Full Text:
- Date Issued: 2014
- Authors: Okeleye, Benjamin Ifeoluwa
- Date: 2014
- Language: English
- Type: Thesis , Masters , MSc (Microbiology)
- Identifier: vital:11282 , http://hdl.handle.net/10353/d1016165
- Description: Cells are constantly exposed to a variety of oxidizing agents, some of which are necessary for life. Oxidants produced in excess can cause an imbalance, leading to oxidative stress, especially in chronic bacterial, viral, and parasitic infections. This can result to damage of biomolecules such as lipids, proteins, and DNA, hence, an increased risk for cancer. Plants have a long history of use in the treatment of cancer. Plant secondary metabolites have proved to be an excellent reservoir of new medical compounds. Fruits, vegetables, and whole grains contain a wide variety of antioxidant phytochemicals, such as phenolics and carotenoids, and may help protect cellular systems from oxidative damage and also may lower the risk of chronic diseases. Peltophorum africanum, a member of the family Fabaceae (Sond) is also known as the African weeping wattle and is used in traditional medicine in South Africa. This study investigated the antimicrobial, antioxidant and antiproliferative potential of the ethyl acetate extract and compounds of Peltophorum africanum in order to validate its pharmacological use. The study assessed the in vitro antimicrobial activity of ethyl acetate extract (EAE) of Peltophorum africanum stem bark and its fractions by the agar well and macrodilution methods. The toxicity on a normal human liver cell (Chang liver cell) and antiproliferation of human breast (MCF-7), colon (HT-29) and cervical (HeLa) cancer cell lines were determined using the CellTiter-Blue cell viability assay and the mechanism of action delineated using the Nucleic Acid and Protein Purification Nucleospin® Tissue Kit, Scanning Electron Microscopy (SEM), Propidium iodide (PI) and Acridine orange (AO) double-staining techniques, the Cleaved Caspase 3 (Asp 175) Alexa Fluor® 488 Antibody and the Coulter® DNA PrepTM Reagents Kit. Purification and identification of the compounds from EAE and fractions as well as the morphological alteration of bacteria, yeast and cancer cells were determined using thin layer chromatography, infrared spectra fingerprint and GC-MS analysis, micro-dilution and scanning electron microscopy with energy-dispersive X-ray analysis. In vitro antioxidant activity of EAE was determined by means of radical scavenging and ferric reducing power analysis using 2, 2-diphenyl-1-picrylhydrazyl (DPPH), 2, 2`-azino-bis (3-ethylbenzthiazoline-6-sulfonic acid) (ABTS) kit, hydrogen peroxide (H2O2), iron (iii) chloride (Fe3+) and nitric oxide (NO). To assess the likely effects of secondary metabolites on the activities observed; total proanthocyanidins, phenolics, flavonols, and flavonoids were determined using standard phytochemical methods. Data were analyzed by one way analysis of variance (ANOVA; SPSS Version 17.0, 2011), regression analysis (MINITAB, version 12 for windows), probit analysis test (software NCSS, 2007) and GraphPad Prism4 software package. The p-values < 0.05 were considered significant. Marked activity of the extract was observed against Plesiomonas shigelloides ATCC 51903, with MIC and MLC values of 0.15625 and 0.3125mg/mL, respectively. The extract was both bactericidal (MICindex ≤ 2) and bacteriostatic/fungistatic (MICindex > 2) in activity. Lethal dose at 50 (LD50) showed 82.64 ± 1.40 degree of toxicity at 24 hrs, and 95 percentile of cell death dose activity ranged from log 3.12 ± 0.01 to 4.59 ± 0.03. The activity of the eight fractions tested ranged from 1.0 ± 0.5 to 3.7 ± 1.6 mg/mL (IC50) and from 2.1 ± 0.8 to 6.25 ± 0 mg/mL (IC90) (Chapter 3). Due to the effect of compounds present in the crude extract and fractions, the P. aeruginosa treated with EAE had a reduction of sodium from 5.55 % (untreated) - 1.50 %. For C. albicans, pottasium was reduced from 4.16 % (untreated) - 0.76 % (T1). Remarkable morphological alterations were observed including deformation of the germ tubes and perforation of the cell wall (Chapter 4). Extract scavenging activity of 88.73± 6.69 % (25 μg mL-1), 53.93±1.09 % (25 μg mL-1) were recorded for H2O2 and NO respectively with proanthocyanidins (92.18±4.68 mg/g) occurring more (p < 0.05) in the extract compared to all other phenolics compounds (Chapter 5). Significant reduction in cell viability of the cells was noted as the MCF-7 cells were reduced from 100 - 54.33±1.84 % after 72 hrs of treatment with 5 μg/mL of EAE (P. value < 0.05). TEt10 was cytotoxic against human normal cells (chang liver cell) at EC50 of 37 μg/mL and 74 μg/mL after 24 and 48 h of treatment respectively. Marked antiproliferative activity of 13.2 μg/mL (EC50) was observed when HeLa cells were treated for 48 h. Internucleosomal DNA of MCF-7, HT-29 and HeLa cells randomly fragmented into an uninterrupted spectrum of sizes, complemented by the intercalation of nucleic acid-specific fluorochromes by PI and AO spotting two phases of apoptosis; early (EA) and late (LA) apoptosis. Distinctive ultramorphological changes observed include; cell shrinkage, membrane blebbing, and typical cell induced death. The study also recorded 705.102 ± 28.56 % TEt10 caspase-3 activity compared to curcumin 592.857 ± 165.76 % (positive control) and untreated (negative control; 100 ± 15.81 %) cells. Percentage HeLa cell with Sub-G1 DNA phase increased from 0.13 ± 0.06 % (negative control) to 13.8 ± 3.04 % compared to curcumin (8.17 ± 2.20 %) after treatment with TEt10. The compounds identified in the fractions including Colchicine, N-(trifluoroacetyl)methyl-N-deacetyl-, Lupeol and .gamma.-Sitosterol may be responsible for the induction of apoptosis observed and could be further studied in vivo as a potential template for new anticancer treatment (Chapter 6 & 7).
- Full Text:
- Date Issued: 2014
Study of the interrelationship between weld geometry, process variables and joint intergrity for friction processed AA6082-T6 aluminium
- Authors: Samuel, Darren Alton Graham
- Date: 2014
- Subjects: Friction welding -- Research Pressure welding , Welding
- Language: English
- Type: Thesis , Doctoral , DPhil
- Identifier: http://hdl.handle.net/10948/48058 , vital:40467
- Description: This work presents a broad overview of the successful development of friction taper stud welding (FTSW) in 25mm thick AA6082-T6 sections. It covers the selection of geometry and process parameters, the development of data logging equipment, energy input results and interpretations. Research was carried out to develop the FTSW process for application in 25mm AA6082-T6 sections. The development and application of the FTSW process addresses the need to fill blind holes in thick aluminium sections for the repair of incorrectly drilled holes, friction stir welding exit holes and defects in critical components. During welding, frictional torque, rotational speed, axial force, near interface temperature of the tapered hole and welding time was recorded. This data was used to calculate energy input and energy input rates throughout a weld, enabling the effect of process parameters to be linked to energy, temperature, microhardness and static joint strength. Results of preliminary experiments are included in the study that were used for the design of a process parameter test window for FTSW in AA6082-T6, as no parameters were available to indicate a starting point for the research. The effect of process parameters on the static joint strength at the base of the tapered hole are presented; using a parallel sided stud and tapered hole configuration. This addresses one of the pressing issues facing FTSW of AA6082-T6, namely the lack of bonding at the bottom of the blind hole. A final process parameter matrix is designed based on the process development welds and is presented and discussed. In addition, the use of a non-consumable heat sink was investigated to prevent the premature collapse of the stud during welding and was shown to be critically important to the FTSW of AA6082-T6. To achieve good sidewall bonding a hole taper angle of 60° is required, this having been shown during visual evaluation of development welds. Stud taper angles between 2° and 5° less than the taper angle of the hole were identified as the range within which good FTSW can be made. With this geometry, at no stage during welding did the body of the stud shear off from the weld interface due to softening, thereby preventing collapse of the stud and formation of poorly bonded regions at the sidewall of the hole. The absence of shearing off of the weld interface during plunge was shown to be a good indicator of appropriate geometry and can be linked to welds made with high hole and stud taper angles and high axial force ramp up rates. The large hole and stud diameter relative to the depth of the hole and the large taper angle of the hole further aid in keeping the weld nugget rotating in the hole, promoting plasticization of the sidewall. Axial force ramp up rate was found to be the main critical success factor in an AA6082-T6 FTSW. Without control of this parameter the body of the stud will heat and detrimentally soften during plunge. It was established that good FTSW in AA6082-T6 cannot be made without the use of preheat to overcome the heat dissipation during welding, and is directly linked to improved energy input characteristics. Energy input as well as energy input rate were directly linked to static tensile strength and softening in the HAZ. The angle of the stud has been related to the energy input rate limit of the stud body, with increasing stud taper angles enabling the stud to withstand a higher energy input rate, allowing the weld interface to propagate up the hole at a slower rate, promoting plasticization of the sidewall. This study has successfully made good FTSW in 25mm thick AA6082-T6, in a 60°, 20mm deep tapered hole. Process parameters and ranges that produce FTSW exhibiting the required characteristics were identified by this study.
- Full Text:
- Date Issued: 2014
- Authors: Samuel, Darren Alton Graham
- Date: 2014
- Subjects: Friction welding -- Research Pressure welding , Welding
- Language: English
- Type: Thesis , Doctoral , DPhil
- Identifier: http://hdl.handle.net/10948/48058 , vital:40467
- Description: This work presents a broad overview of the successful development of friction taper stud welding (FTSW) in 25mm thick AA6082-T6 sections. It covers the selection of geometry and process parameters, the development of data logging equipment, energy input results and interpretations. Research was carried out to develop the FTSW process for application in 25mm AA6082-T6 sections. The development and application of the FTSW process addresses the need to fill blind holes in thick aluminium sections for the repair of incorrectly drilled holes, friction stir welding exit holes and defects in critical components. During welding, frictional torque, rotational speed, axial force, near interface temperature of the tapered hole and welding time was recorded. This data was used to calculate energy input and energy input rates throughout a weld, enabling the effect of process parameters to be linked to energy, temperature, microhardness and static joint strength. Results of preliminary experiments are included in the study that were used for the design of a process parameter test window for FTSW in AA6082-T6, as no parameters were available to indicate a starting point for the research. The effect of process parameters on the static joint strength at the base of the tapered hole are presented; using a parallel sided stud and tapered hole configuration. This addresses one of the pressing issues facing FTSW of AA6082-T6, namely the lack of bonding at the bottom of the blind hole. A final process parameter matrix is designed based on the process development welds and is presented and discussed. In addition, the use of a non-consumable heat sink was investigated to prevent the premature collapse of the stud during welding and was shown to be critically important to the FTSW of AA6082-T6. To achieve good sidewall bonding a hole taper angle of 60° is required, this having been shown during visual evaluation of development welds. Stud taper angles between 2° and 5° less than the taper angle of the hole were identified as the range within which good FTSW can be made. With this geometry, at no stage during welding did the body of the stud shear off from the weld interface due to softening, thereby preventing collapse of the stud and formation of poorly bonded regions at the sidewall of the hole. The absence of shearing off of the weld interface during plunge was shown to be a good indicator of appropriate geometry and can be linked to welds made with high hole and stud taper angles and high axial force ramp up rates. The large hole and stud diameter relative to the depth of the hole and the large taper angle of the hole further aid in keeping the weld nugget rotating in the hole, promoting plasticization of the sidewall. Axial force ramp up rate was found to be the main critical success factor in an AA6082-T6 FTSW. Without control of this parameter the body of the stud will heat and detrimentally soften during plunge. It was established that good FTSW in AA6082-T6 cannot be made without the use of preheat to overcome the heat dissipation during welding, and is directly linked to improved energy input characteristics. Energy input as well as energy input rate were directly linked to static tensile strength and softening in the HAZ. The angle of the stud has been related to the energy input rate limit of the stud body, with increasing stud taper angles enabling the stud to withstand a higher energy input rate, allowing the weld interface to propagate up the hole at a slower rate, promoting plasticization of the sidewall. This study has successfully made good FTSW in 25mm thick AA6082-T6, in a 60°, 20mm deep tapered hole. Process parameters and ranges that produce FTSW exhibiting the required characteristics were identified by this study.
- Full Text:
- Date Issued: 2014
Study South Africa
- International Education Association of South Africa (IEASA), Jooste, Nico
- Authors: International Education Association of South Africa (IEASA) , Jooste, Nico
- Date: 2014
- Subjects: Education, Higher -- South Africa , Education and globalization -- South Africa Student mobility -- Africa International education -- South Africa Education, Higher -- International cooperation , Universities and colleges -- South Africa , Technical Institutes -- South Africa , Vocational guidance -- South Africa
- Language: English
- Type: text , book
- Identifier: http://hdl.handle.net/10962/64864 , vital:28621 , ISBN 9780620620123
- Description: [Editor's Letter]: This 14th edition of Study South Africa foregrounds the celebration of 20 years of a democratic South Africa. Patrick Fish was commissioned to write a series of articles reflecting the development of South African Higher Education since 1994 for this edition. Reading through this the reader will hopefully experience a sense of the transformation of the South African Higher Education system. Although we all agree in South Africa that we are not done yet, we also recognise that given the South African realities, the change from a race based and fragmented system of higher education to a single but diverse system is well under way. The South African Universities transformed from mostly mono cultural to multicultural institutions that largely reflects the composition of the South African population. The University campuses also demonstrate the institutional appetite to be international. Not only do they jointly house more than 50,000 international students but are also involved in numerous ways in bringing the benefits of being globally connected to the local communities. We are one of the few higher education systems that largely fund our international activities from institutional budgets. This is one of the main reasons that South African Universities practice a style of internationalisation that is relevant to our institutional needs, as well as the local and national needs. Through our internationalisation endeavours we have connected with the rest of Africa in a very special way. Not only do we educate large numbers of students from other African countries but through the South African Higher Education alumni that now live all over the African continent we have built permanent connections that will enhance and develop long standing relationships. IEASA celebrates with all South Africans 20 years of democracy and realise that it is indeed a privilege to be practitioners in transformed ‘knowledge cities’. We are, however, saddened by the incidents of intolerance and destruction in other parts of the world that make the work of higher education institutions impossible, and can only in solidarity with those scholars at risk celebrate with deep appreciation the efforts and determination of those South Africans that made it possible for us to be Universities in a free and democratic society. , 14th Edition
- Full Text:
- Date Issued: 2014
- Authors: International Education Association of South Africa (IEASA) , Jooste, Nico
- Date: 2014
- Subjects: Education, Higher -- South Africa , Education and globalization -- South Africa Student mobility -- Africa International education -- South Africa Education, Higher -- International cooperation , Universities and colleges -- South Africa , Technical Institutes -- South Africa , Vocational guidance -- South Africa
- Language: English
- Type: text , book
- Identifier: http://hdl.handle.net/10962/64864 , vital:28621 , ISBN 9780620620123
- Description: [Editor's Letter]: This 14th edition of Study South Africa foregrounds the celebration of 20 years of a democratic South Africa. Patrick Fish was commissioned to write a series of articles reflecting the development of South African Higher Education since 1994 for this edition. Reading through this the reader will hopefully experience a sense of the transformation of the South African Higher Education system. Although we all agree in South Africa that we are not done yet, we also recognise that given the South African realities, the change from a race based and fragmented system of higher education to a single but diverse system is well under way. The South African Universities transformed from mostly mono cultural to multicultural institutions that largely reflects the composition of the South African population. The University campuses also demonstrate the institutional appetite to be international. Not only do they jointly house more than 50,000 international students but are also involved in numerous ways in bringing the benefits of being globally connected to the local communities. We are one of the few higher education systems that largely fund our international activities from institutional budgets. This is one of the main reasons that South African Universities practice a style of internationalisation that is relevant to our institutional needs, as well as the local and national needs. Through our internationalisation endeavours we have connected with the rest of Africa in a very special way. Not only do we educate large numbers of students from other African countries but through the South African Higher Education alumni that now live all over the African continent we have built permanent connections that will enhance and develop long standing relationships. IEASA celebrates with all South Africans 20 years of democracy and realise that it is indeed a privilege to be practitioners in transformed ‘knowledge cities’. We are, however, saddened by the incidents of intolerance and destruction in other parts of the world that make the work of higher education institutions impossible, and can only in solidarity with those scholars at risk celebrate with deep appreciation the efforts and determination of those South Africans that made it possible for us to be Universities in a free and democratic society. , 14th Edition
- Full Text:
- Date Issued: 2014
Subjects and citizens
- Authors: Badat, Saleem
- Date: 20-Jan-14
- Language: English
- Type: Text
- Identifier: vital:7863 , http://hdl.handle.net/10962/d1016412
- Full Text:
- Date Issued: 20-Jan-14
- Authors: Badat, Saleem
- Date: 20-Jan-14
- Language: English
- Type: Text
- Identifier: vital:7863 , http://hdl.handle.net/10962/d1016412
- Full Text:
- Date Issued: 20-Jan-14
Successful identification of the final instar nymph of Quintilia carinata (Thunberg)(Hemiptera: Cicadidae) by DNA extraction from the exuvium
- Bouwer, Nicolette, Midgley, John M, Timm, Alicia E, Villet, Martin H
- Authors: Bouwer, Nicolette , Midgley, John M , Timm, Alicia E , Villet, Martin H
- Date: 2014
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/442347 , vital:73977 , https://doi.org/10.1080/00222933.2013.836759
- Description: Despite being taxonomically and phylogenetically informative, the morphology of the immature stages of cicadas has received comparatively superficial attention. One reason for this is the difficulty of positively identifying immature stages, particularly as these stages are fossorial. We present a method for identifying cicada exuviae using DNA sequence data and describe a set of characters and character states for the final instar nymph of Quintilia carinata (Thunberg). The identification of immature stages using molecular methods will increase our knowledge of African cicadas, allowing for the initiation of future phylogenetic and ecological comparisons.
- Full Text:
- Date Issued: 2014
- Authors: Bouwer, Nicolette , Midgley, John M , Timm, Alicia E , Villet, Martin H
- Date: 2014
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/442347 , vital:73977 , https://doi.org/10.1080/00222933.2013.836759
- Description: Despite being taxonomically and phylogenetically informative, the morphology of the immature stages of cicadas has received comparatively superficial attention. One reason for this is the difficulty of positively identifying immature stages, particularly as these stages are fossorial. We present a method for identifying cicada exuviae using DNA sequence data and describe a set of characters and character states for the final instar nymph of Quintilia carinata (Thunberg). The identification of immature stages using molecular methods will increase our knowledge of African cicadas, allowing for the initiation of future phylogenetic and ecological comparisons.
- Full Text:
- Date Issued: 2014
Sustainability Assessment of University of Gondar, Gondar, North-west Ethiopia
- Moges, Haimanot G, Kifle, Desalegn W, Lotz-Sisitka, Heila, Woldyohhanes, Solomon M
- Authors: Moges, Haimanot G , Kifle, Desalegn W , Lotz-Sisitka, Heila , Woldyohhanes, Solomon M
- Date: 2014
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/182845 , vital:43885 , xlink:href="https://doi.org/10.1177/0973408214529990"
- Description: The purpose of this article is to provide an overview of the cross-institutional assessment of sustainable development practices in the University of Gondar (UoG). The focus of the assessment was the level of UoG academic departments’ integration of sustainability concerns in teaching, research and community service. Management contributions to sustainable development, student initiatives on sustainability issues and policy statements about sustainable development of UoG were also considered in the assessment. The data collection was based on the Unit-based Sustainability Assessment Tool (USAT); in addition, supplementary information was collected through observations across the four campuses of UoG from January to February 2012.The result of the assessment showed that only a few academic departments have incorporated sustainability concerns in their curricula and teaching approach. The initiation and commitment of academic departments in mainstreaming sustainability concerns in the research and community service delivered were relatively poor. The operation and management of UoG showed inadequate sustainable development practices on waste management, energy utilization and purchasing from environment-friendly companies. In addition, the written policy and statements of UoG did not reflect sustainability in an explicit manner. The university is expected to respond to the key themes defined through sustainability declarations on higher education; there is also a need to establish the relevance of these in relation to the systemic environment. From the study undertaken, we have learnt that sustainability assessment of universities using USAT will be more valuable, if universities have already initiated the embedding of sustainability so that USAT can be used to benchmark the continual improvement.
- Full Text:
- Date Issued: 2014
- Authors: Moges, Haimanot G , Kifle, Desalegn W , Lotz-Sisitka, Heila , Woldyohhanes, Solomon M
- Date: 2014
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/182845 , vital:43885 , xlink:href="https://doi.org/10.1177/0973408214529990"
- Description: The purpose of this article is to provide an overview of the cross-institutional assessment of sustainable development practices in the University of Gondar (UoG). The focus of the assessment was the level of UoG academic departments’ integration of sustainability concerns in teaching, research and community service. Management contributions to sustainable development, student initiatives on sustainability issues and policy statements about sustainable development of UoG were also considered in the assessment. The data collection was based on the Unit-based Sustainability Assessment Tool (USAT); in addition, supplementary information was collected through observations across the four campuses of UoG from January to February 2012.The result of the assessment showed that only a few academic departments have incorporated sustainability concerns in their curricula and teaching approach. The initiation and commitment of academic departments in mainstreaming sustainability concerns in the research and community service delivered were relatively poor. The operation and management of UoG showed inadequate sustainable development practices on waste management, energy utilization and purchasing from environment-friendly companies. In addition, the written policy and statements of UoG did not reflect sustainability in an explicit manner. The university is expected to respond to the key themes defined through sustainability declarations on higher education; there is also a need to establish the relevance of these in relation to the systemic environment. From the study undertaken, we have learnt that sustainability assessment of universities using USAT will be more valuable, if universities have already initiated the embedding of sustainability so that USAT can be used to benchmark the continual improvement.
- Full Text:
- Date Issued: 2014
Sustainable development principles in the implementation of the MyCITI transport system in Cape Town
- Authors: Nocanda, Nosabatha
- Date: 2014
- Subjects: Sustainable development -- South Africa -- Cape Town , Transportation -- South Africa -- Cape Town
- Language: English
- Type: Thesis , Masters , MA
- Identifier: http://hdl.handle.net/10948/8912 , vital:26442
- Description: South Africa is a signatory to several agreements dealing with sustainable development. South Africa has also committed to meeting several Millennium Development Goals (MDGs). One of the biggest challenges facing South Africa, like many other countries, is to maintain a balance between the quest for economic growth and sustainable development. In pursuing economic success, it is often the case that insufficient time and effort are dedicated to determining whether the planned developments support sustainability principles. In some instances, developments may meet one or two sustainability principles whilst violating a number of others, potentially leading to undesirable social, economic or environmental consequences. Countries ought to ensure that projects they approve for development at local, provincial or national level are subjected to thorough scrutiny to ascertain that there is minimal violation of sustainable development principles. The development of the MyCiTi bus transport system in the City of Cape Town was assessed for its consideration of sustainable development principles during the implementation of the project. Several users and non-users of MyCiTi were interviewed regarding their experience and observation of MyCiTi’s development and roll-out relative to sustainable development principles. The results obtained are discussed in this study and the appropriate recommendations given.
- Full Text:
- Date Issued: 2014
Sustainable development principles in the implementation of the MyCITI transport system in Cape Town
- Authors: Nocanda, Nosabatha
- Date: 2014
- Subjects: Sustainable development -- South Africa -- Cape Town , Transportation -- South Africa -- Cape Town
- Language: English
- Type: Thesis , Masters , MA
- Identifier: http://hdl.handle.net/10948/8912 , vital:26442
- Description: South Africa is a signatory to several agreements dealing with sustainable development. South Africa has also committed to meeting several Millennium Development Goals (MDGs). One of the biggest challenges facing South Africa, like many other countries, is to maintain a balance between the quest for economic growth and sustainable development. In pursuing economic success, it is often the case that insufficient time and effort are dedicated to determining whether the planned developments support sustainability principles. In some instances, developments may meet one or two sustainability principles whilst violating a number of others, potentially leading to undesirable social, economic or environmental consequences. Countries ought to ensure that projects they approve for development at local, provincial or national level are subjected to thorough scrutiny to ascertain that there is minimal violation of sustainable development principles. The development of the MyCiTi bus transport system in the City of Cape Town was assessed for its consideration of sustainable development principles during the implementation of the project. Several users and non-users of MyCiTi were interviewed regarding their experience and observation of MyCiTi’s development and roll-out relative to sustainable development principles. The results obtained are discussed in this study and the appropriate recommendations given.
- Full Text:
- Date Issued: 2014
Sustainable governance management systems: a practical approach for Water Boards in South Africa
- Authors: Ntili, Tseliso Paul
- Date: 2014
- Subjects: South Africa. Department of Water Affairs and Forestry , Water-supply -- South Africa -- Management , Water quality -- Government policy -- South Africa
- Language: English
- Type: Thesis , Doctoral , DPhil
- Identifier: http://hdl.handle.net/10948/9185 , vital:26472
- Description: This research study explored the appropriate sustainable governance management systems for South African socio-economic conditions. This was achieved by investigating the current governance and management of water boards in performing their business and water services provisioning at municipal level. Municipalities are the third sphere of government in South Africa and are found at local levels of governance. They are businesses that provide running water as legislated by the Constitution of the Republic of South Africa, 1996. Water boards are public institutions established in terms of the Water Services Act, 108 of 1997 (WSA) and listed as Schedule 3 part B: National Government Business Enterprise in terms of the Public Finance Management Act 29 of 1999. They are accountable to the national government through the Department of Water Affairs. Their responsibility is to support municipalities where water-provisioning challenges are eminent. They report annually to national parliament on their performance within a specific financial year. Water boards are currently able to perform their operations in selected jurisdictions as contracted by municipalities. They are struggling in managing and governing their water business while striving to achieve improvements in water service coverage, operating efficiency and service delivery. The aim of the research study was to investigate areas affecting the sustainability of governance management systems for water boards in relation to the improvement of service delivery in South Africa. The analysis of age and gender factors and the conditions affecting governance are explored. The research used the qualitative and quantitative methods to analyse the research questions. Prior to the commencement of the study, the researcher performed an intensive desktop study involving the use of dated and recently published material related to governance and management of the water institutions in developed and developing countries. During the desktop study, national and international accredited journals were prioritised to obtain related and relevant similar information to the water governance and management of water institutions. In addition, a case study was undertaken in Ficksburg in which water boards provided an intervention in resolving the water crisis, since the provision of water is a basic service at local government. This area experienced both water shortage and a poor quality of water. With regard to qualitative methodology, participatory forums were used to delineate the research context and premise. The study population consisted of individuals who were in the business of water boards with special reference to water management and board of directors for a population of 1 000. Of the 500 questionnaires sent out, 419 were returned. The data were analysed using the statistical software package, Statistical Package for Social Sciences (SPSS). The results and recommendations are presented based on the identified objectives of the study. The study’s findings provide information for transformation and improvement in the performance of water boards in South Africa when striving for sustainability in management and governance. The findings reveal the need for improvements in the involvement of females in the business of the water boards. The findings confirm the outcomes of previous studies regarding the slow implementation of affirmative action and transformation processes as required by legislation. Furthermore, the results reveal that the factors and conditions affecting sustainability of the water boards need to be prioritised to improve the management and governance aspects of water boards. These include the appropriate selection of members of the boards of directors, water boards' committees that are guided by legislation in their operations and the maintenance of proper financial management (collection of revenue, implementation of appropriate financial strategies and striving for positive clean audit). Water boards are encouraged to strengthen their intergovernmental relations in order to make their mandate known across all spheres of government. Service delivery should be approached “from source to tap and tap to source” to promote high-quality provision of water. The water boards should be accountable to the municipalities for the provision of delegated operations. The Department of Water Affairs exercises an oversight role to ensure the sustainable provision of the services. However, the study concludes that without a strong management and a sustainable governance approach, water boards will not be able to carry out its water developmental mandate. The practical framework that was developed in this study provides management and governance tools for sustained provisioning of water to advance transformational and developmental needs and the application of legislations. The results in the study have a direct impact on the codes of practice and regulations on employment equity in implementing the Employment Equity Act of 1998, Intergovernmental Relations Act of 2005, Companies Act of 2008, National Water Act of 1998, and Water Services Act of 1997. Therefore, the practical implementation of this framework will enhance water as a transformational and developmental feature in addressing the social, environmental and economic services.
- Full Text:
- Date Issued: 2014
- Authors: Ntili, Tseliso Paul
- Date: 2014
- Subjects: South Africa. Department of Water Affairs and Forestry , Water-supply -- South Africa -- Management , Water quality -- Government policy -- South Africa
- Language: English
- Type: Thesis , Doctoral , DPhil
- Identifier: http://hdl.handle.net/10948/9185 , vital:26472
- Description: This research study explored the appropriate sustainable governance management systems for South African socio-economic conditions. This was achieved by investigating the current governance and management of water boards in performing their business and water services provisioning at municipal level. Municipalities are the third sphere of government in South Africa and are found at local levels of governance. They are businesses that provide running water as legislated by the Constitution of the Republic of South Africa, 1996. Water boards are public institutions established in terms of the Water Services Act, 108 of 1997 (WSA) and listed as Schedule 3 part B: National Government Business Enterprise in terms of the Public Finance Management Act 29 of 1999. They are accountable to the national government through the Department of Water Affairs. Their responsibility is to support municipalities where water-provisioning challenges are eminent. They report annually to national parliament on their performance within a specific financial year. Water boards are currently able to perform their operations in selected jurisdictions as contracted by municipalities. They are struggling in managing and governing their water business while striving to achieve improvements in water service coverage, operating efficiency and service delivery. The aim of the research study was to investigate areas affecting the sustainability of governance management systems for water boards in relation to the improvement of service delivery in South Africa. The analysis of age and gender factors and the conditions affecting governance are explored. The research used the qualitative and quantitative methods to analyse the research questions. Prior to the commencement of the study, the researcher performed an intensive desktop study involving the use of dated and recently published material related to governance and management of the water institutions in developed and developing countries. During the desktop study, national and international accredited journals were prioritised to obtain related and relevant similar information to the water governance and management of water institutions. In addition, a case study was undertaken in Ficksburg in which water boards provided an intervention in resolving the water crisis, since the provision of water is a basic service at local government. This area experienced both water shortage and a poor quality of water. With regard to qualitative methodology, participatory forums were used to delineate the research context and premise. The study population consisted of individuals who were in the business of water boards with special reference to water management and board of directors for a population of 1 000. Of the 500 questionnaires sent out, 419 were returned. The data were analysed using the statistical software package, Statistical Package for Social Sciences (SPSS). The results and recommendations are presented based on the identified objectives of the study. The study’s findings provide information for transformation and improvement in the performance of water boards in South Africa when striving for sustainability in management and governance. The findings reveal the need for improvements in the involvement of females in the business of the water boards. The findings confirm the outcomes of previous studies regarding the slow implementation of affirmative action and transformation processes as required by legislation. Furthermore, the results reveal that the factors and conditions affecting sustainability of the water boards need to be prioritised to improve the management and governance aspects of water boards. These include the appropriate selection of members of the boards of directors, water boards' committees that are guided by legislation in their operations and the maintenance of proper financial management (collection of revenue, implementation of appropriate financial strategies and striving for positive clean audit). Water boards are encouraged to strengthen their intergovernmental relations in order to make their mandate known across all spheres of government. Service delivery should be approached “from source to tap and tap to source” to promote high-quality provision of water. The water boards should be accountable to the municipalities for the provision of delegated operations. The Department of Water Affairs exercises an oversight role to ensure the sustainable provision of the services. However, the study concludes that without a strong management and a sustainable governance approach, water boards will not be able to carry out its water developmental mandate. The practical framework that was developed in this study provides management and governance tools for sustained provisioning of water to advance transformational and developmental needs and the application of legislations. The results in the study have a direct impact on the codes of practice and regulations on employment equity in implementing the Employment Equity Act of 1998, Intergovernmental Relations Act of 2005, Companies Act of 2008, National Water Act of 1998, and Water Services Act of 1997. Therefore, the practical implementation of this framework will enhance water as a transformational and developmental feature in addressing the social, environmental and economic services.
- Full Text:
- Date Issued: 2014
Sustainable rural development projects in Ficksburg Local Municipality
- Authors: Mamotho, Mpho Benett
- Date: 2014
- Subjects: Participatory rural appraisal -- South Africa -- Ficksburg , Rural development projects -- South Africa -- Ficksburg
- Language: English
- Type: Thesis , Masters , MA
- Identifier: http://hdl.handle.net/10948/5751 , vital:20996
- Description: The current study aimed to evaluation of a Rural Development project in this case the (Kabelo Trust), by evaluating the factors that contributes to its sustainability even though 70% of the members did not undergo high school education. Qualitative research methods was employed in gathering accurate information from the project members about the strategies that they are employing in sustaining the project while many government funded project does not last for even a year. The involvement of the stakeholders like Setsoto Local Municipality, the Department of Agriculture and the Department of Rural Development and Land Reform, the role they played in the project was also explored. It was therefore suggested by the researcher that the main stakeholder which is the Department of Agriculture should assist the project in establishing market for products in other countries.
- Full Text:
- Date Issued: 2014
- Authors: Mamotho, Mpho Benett
- Date: 2014
- Subjects: Participatory rural appraisal -- South Africa -- Ficksburg , Rural development projects -- South Africa -- Ficksburg
- Language: English
- Type: Thesis , Masters , MA
- Identifier: http://hdl.handle.net/10948/5751 , vital:20996
- Description: The current study aimed to evaluation of a Rural Development project in this case the (Kabelo Trust), by evaluating the factors that contributes to its sustainability even though 70% of the members did not undergo high school education. Qualitative research methods was employed in gathering accurate information from the project members about the strategies that they are employing in sustaining the project while many government funded project does not last for even a year. The involvement of the stakeholders like Setsoto Local Municipality, the Department of Agriculture and the Department of Rural Development and Land Reform, the role they played in the project was also explored. It was therefore suggested by the researcher that the main stakeholder which is the Department of Agriculture should assist the project in establishing market for products in other countries.
- Full Text:
- Date Issued: 2014
Swift heavy ion radiation damage in nanocrystalline ZrN
- Authors: Janse van Vuuren, Arno
- Date: 2014
- Subjects: Zirconium -- Effect of radiation on , Nanocrystals
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:10550 , http://hdl.handle.net/10948/d1020147
- Description: ZrN has been identified as a candidate material for use as an inert matrix fuel host for the transmutation of plutonium and minor actinides. These materials will be subjected to large amounts of different types of radiation within the nuclear reactor core. The types of radiation include fission fragments and alpha-particles amongst others. Recent studies suggest that nanocrystalline material may have a higher radiation tolerance than their polycrystalline and bulk counterparts. Some studies have shown that swift heavy ion irradiation may also significantly modulate hydrogen and helium behaviour in materials. This phenomenon is also of considerable practical interest for inert matrix fuel hosts, since these materials accumulate helium via (n,) reactions and will also be subjected to irradiation by fission fragments. The aim of this investigation is therefore to study the effects of fission fragment and alpha particle irradiation on nanocrystalline ZrN. In an effort to simulate the effects of fission fragments on nanocrystalline zirconium nitride different layers (on a Si substrate) of various thicknesses (0.1, 3, 10 and 20 μm) were irradiated with 167 MeV Xe, 250 MeV Kr and 695 MeV Bi ions to fluences in the range from 31012 to 2.61015 cm-2 for Xe, 1×1013 to 7.06×1013 cm-2 for Kr and 1012 to 1013 cm-2 for Bi. The purpose of this irradiation is to simulate the effects of fission fragments on nanocrystalline ZrN. In order to simulate the effects of alpha particles and the combined effects of alpha particles and fission fragments on nanocrystalline ZrN it was irradiated with 30 keV He to fluences between 1016 and 5×1016 cm-2, 167 MeV Xe to fluences between 5×1013 and 1014 cm-2 and also 695 MeV Bi to a fluence of 1.5×1013 cm-2. He/Bi and He/Xe irradiated samples were annealed at temperatures between 600 and 1000 °C. The different irradiated layers were subsequently analysed via X-ray diffraction (XRD), μ-Raman, transmission electron microscopy (TEM) and nano indentation hardness testing (NIH) techniques. XRD, TEM, μ-Raman and NIH results indicate that ZrN has a very high tolerance to the effects of high energy irradiation. The microstructure of nanocrystalline ZrN remains unaffected by electronic excitation effects even at a very high stopping power. TEM and SEM results indicated that post irradiation heat treatment induces exfoliation at a depth that corresponds to the end-of-range of 30 keV He ions. Results from He/Xe irradiated samples revealed that electronic excitation effects, due to Xe ions, suppress helium blister formation and consequently the exfoliation processes. He/Bi samples however do not show the same effects, but this is possibly due to the lower fluence of Bi ions. This suggests that nanocrystalline ZrN is prone to the formation of He blisters which may ultimately lead material failure. These effects may however be mitigated by electronic excitation effects from certain SHIs.
- Full Text:
- Date Issued: 2014
- Authors: Janse van Vuuren, Arno
- Date: 2014
- Subjects: Zirconium -- Effect of radiation on , Nanocrystals
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:10550 , http://hdl.handle.net/10948/d1020147
- Description: ZrN has been identified as a candidate material for use as an inert matrix fuel host for the transmutation of plutonium and minor actinides. These materials will be subjected to large amounts of different types of radiation within the nuclear reactor core. The types of radiation include fission fragments and alpha-particles amongst others. Recent studies suggest that nanocrystalline material may have a higher radiation tolerance than their polycrystalline and bulk counterparts. Some studies have shown that swift heavy ion irradiation may also significantly modulate hydrogen and helium behaviour in materials. This phenomenon is also of considerable practical interest for inert matrix fuel hosts, since these materials accumulate helium via (n,) reactions and will also be subjected to irradiation by fission fragments. The aim of this investigation is therefore to study the effects of fission fragment and alpha particle irradiation on nanocrystalline ZrN. In an effort to simulate the effects of fission fragments on nanocrystalline zirconium nitride different layers (on a Si substrate) of various thicknesses (0.1, 3, 10 and 20 μm) were irradiated with 167 MeV Xe, 250 MeV Kr and 695 MeV Bi ions to fluences in the range from 31012 to 2.61015 cm-2 for Xe, 1×1013 to 7.06×1013 cm-2 for Kr and 1012 to 1013 cm-2 for Bi. The purpose of this irradiation is to simulate the effects of fission fragments on nanocrystalline ZrN. In order to simulate the effects of alpha particles and the combined effects of alpha particles and fission fragments on nanocrystalline ZrN it was irradiated with 30 keV He to fluences between 1016 and 5×1016 cm-2, 167 MeV Xe to fluences between 5×1013 and 1014 cm-2 and also 695 MeV Bi to a fluence of 1.5×1013 cm-2. He/Bi and He/Xe irradiated samples were annealed at temperatures between 600 and 1000 °C. The different irradiated layers were subsequently analysed via X-ray diffraction (XRD), μ-Raman, transmission electron microscopy (TEM) and nano indentation hardness testing (NIH) techniques. XRD, TEM, μ-Raman and NIH results indicate that ZrN has a very high tolerance to the effects of high energy irradiation. The microstructure of nanocrystalline ZrN remains unaffected by electronic excitation effects even at a very high stopping power. TEM and SEM results indicated that post irradiation heat treatment induces exfoliation at a depth that corresponds to the end-of-range of 30 keV He ions. Results from He/Xe irradiated samples revealed that electronic excitation effects, due to Xe ions, suppress helium blister formation and consequently the exfoliation processes. He/Bi samples however do not show the same effects, but this is possibly due to the lower fluence of Bi ions. This suggests that nanocrystalline ZrN is prone to the formation of He blisters which may ultimately lead material failure. These effects may however be mitigated by electronic excitation effects from certain SHIs.
- Full Text:
- Date Issued: 2014