Assessment of the flocculating efficiency of bioflocculant produced by bacillus sp. Aemreg4 isolated from Tyhume river, Eastern Cape, South Africa
- Authors: Ntsangani, Nozipho
- Date: 2016
- Subjects: Flocculants
- Language: English
- Type: Thesis , Masters , MSc (Biochemistry)
- Identifier: vital:11357 , http://hdl.handle.net/10353/d1021324
- Description: Bioflocculants are flocculating substances produced by microorganisms during growth and have recently received considerable attention from researchers; due to their biodegradability, non-toxicity and lack of secondary pollution from degradation intermediates. This study evaluated the efficiency of bioflocculant produced by Bacillus sp. AEMREG4 isolated from Tyhume River. The bacterial identification was through 16S rDNA sequencing; nucleotide sequences were deposited in GenBank as Bacillus sp. AEMREG4 with an Accession number KP406729. The optimum culture conditions for bioflocculant production were an inoculum size of 4% (v/v) and starch as well as yeast extract as sole carbon and nitrogen sources respectively. The addition of CaCl2 enhanced the flocculating activity, at a wide range of pH 4-10 and the highest flocculating activity was reached at an initial pH 8 (80%). A bioflocculant yield of 0.78 g was recovered from 1 L of culture broth. The optimum flocculating activity of 78% was reached at the lowest bioflocculant dosage of 0.1 mg/ml and the presence of divalent cations (Ca2+, Mn2+ and Mg2+) as well as a trivalent cation (Al3+) enhanced flocculating activity. The purified bioflocculant retained more than 70% flocculating activity when subjected to heating at 100 °C for 1 h and maximum flocculating activity of 83% was achieved at both acidic and basic pH values of 3 and 10 respectively. Chemical analysis showed that the bioflocculant is predominantly polysaccharide. The Fourier transform infrared (FTIR) spectrum revealed the presence of carboxyl, hydroxyl and methoxyl groups as the functional moieties and the scanning electron microscopy (SEM) imaging of the purified bioflocculant showed its morphological structure as rod-shaped which contributes to its high flocculating efficiency. The high flocculation activity displayed by this bioflocculant indicates its potential suitability for industrial application.Keywords: Bioflocculant, Bacillus sp. AEMREG4, flocculating activity.
- Full Text:
- Date Issued: 2016
- Authors: Ntsangani, Nozipho
- Date: 2016
- Subjects: Flocculants
- Language: English
- Type: Thesis , Masters , MSc (Biochemistry)
- Identifier: vital:11357 , http://hdl.handle.net/10353/d1021324
- Description: Bioflocculants are flocculating substances produced by microorganisms during growth and have recently received considerable attention from researchers; due to their biodegradability, non-toxicity and lack of secondary pollution from degradation intermediates. This study evaluated the efficiency of bioflocculant produced by Bacillus sp. AEMREG4 isolated from Tyhume River. The bacterial identification was through 16S rDNA sequencing; nucleotide sequences were deposited in GenBank as Bacillus sp. AEMREG4 with an Accession number KP406729. The optimum culture conditions for bioflocculant production were an inoculum size of 4% (v/v) and starch as well as yeast extract as sole carbon and nitrogen sources respectively. The addition of CaCl2 enhanced the flocculating activity, at a wide range of pH 4-10 and the highest flocculating activity was reached at an initial pH 8 (80%). A bioflocculant yield of 0.78 g was recovered from 1 L of culture broth. The optimum flocculating activity of 78% was reached at the lowest bioflocculant dosage of 0.1 mg/ml and the presence of divalent cations (Ca2+, Mn2+ and Mg2+) as well as a trivalent cation (Al3+) enhanced flocculating activity. The purified bioflocculant retained more than 70% flocculating activity when subjected to heating at 100 °C for 1 h and maximum flocculating activity of 83% was achieved at both acidic and basic pH values of 3 and 10 respectively. Chemical analysis showed that the bioflocculant is predominantly polysaccharide. The Fourier transform infrared (FTIR) spectrum revealed the presence of carboxyl, hydroxyl and methoxyl groups as the functional moieties and the scanning electron microscopy (SEM) imaging of the purified bioflocculant showed its morphological structure as rod-shaped which contributes to its high flocculating efficiency. The high flocculation activity displayed by this bioflocculant indicates its potential suitability for industrial application.Keywords: Bioflocculant, Bacillus sp. AEMREG4, flocculating activity.
- Full Text:
- Date Issued: 2016
Assessment of the implementation of the National Certificate (Vocational) plant production modules
- Langa, Phakama Perry Macmillan
- Authors: Langa, Phakama Perry Macmillan
- Date: 2016
- Subjects: Curriculum planning Technical education -- Curricula Vocational education -- Curricula
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10353/2359 , vital:27778
- Description: From 2010, the South African vocational skills education is offered by the Department of Higher Education and Training (DHET) through the Technical Vocational Education and Training (TVET) colleges. TVET colleges need to be transformed in order to empower young learners with the skills required by the various sectors of the economy. The purpose of this study was to assess the implementation of the National Certificate (Vocational) Plant Production module in Training and Vocational Education and Training (TVET) Colleges. The sample for this study is concurrent triangulation whereby complementary methods of data sources were brought together to offset each other‘s weaknesses. The sample for this study consisted of participants from three TVET colleges: one deep rural, one semi-rural/semi-urban and one urban in terms of geographical location. A total of 18 participants were interviewed: 2 subject advisors engaged by the colleges, 1 lecturer from college A, 3 lecturers from college B, 2 lecturers from college C, 4 graduates from college B, 3 graduates from college C and 3 employers .Research design for this study has features of both a survey and a case study. The mixed-method approach was applied using document analysis, questionnaires and interviews for data collection. The researcher found out that there is a disparity between the Plant Production guidelines and their implementation and assessment. Among the main reasons for failure to implement the guidelines properly are poor or inadequate infrastructure for doing practical work, high rate of student absenteeism within the investigated categories, and the high drop-out rate at Levels 2–4. To minimize the challenges in offering the Plant Production module, the study recommends that since some colleges cannot afford purchasing large sizes of land to properly implement the Plant Production guidelines, the government and the DHET should link the Primary Agriculture training to the land reform program where students can be trained under the land reform program.
- Full Text:
- Date Issued: 2016
- Authors: Langa, Phakama Perry Macmillan
- Date: 2016
- Subjects: Curriculum planning Technical education -- Curricula Vocational education -- Curricula
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10353/2359 , vital:27778
- Description: From 2010, the South African vocational skills education is offered by the Department of Higher Education and Training (DHET) through the Technical Vocational Education and Training (TVET) colleges. TVET colleges need to be transformed in order to empower young learners with the skills required by the various sectors of the economy. The purpose of this study was to assess the implementation of the National Certificate (Vocational) Plant Production module in Training and Vocational Education and Training (TVET) Colleges. The sample for this study is concurrent triangulation whereby complementary methods of data sources were brought together to offset each other‘s weaknesses. The sample for this study consisted of participants from three TVET colleges: one deep rural, one semi-rural/semi-urban and one urban in terms of geographical location. A total of 18 participants were interviewed: 2 subject advisors engaged by the colleges, 1 lecturer from college A, 3 lecturers from college B, 2 lecturers from college C, 4 graduates from college B, 3 graduates from college C and 3 employers .Research design for this study has features of both a survey and a case study. The mixed-method approach was applied using document analysis, questionnaires and interviews for data collection. The researcher found out that there is a disparity between the Plant Production guidelines and their implementation and assessment. Among the main reasons for failure to implement the guidelines properly are poor or inadequate infrastructure for doing practical work, high rate of student absenteeism within the investigated categories, and the high drop-out rate at Levels 2–4. To minimize the challenges in offering the Plant Production module, the study recommends that since some colleges cannot afford purchasing large sizes of land to properly implement the Plant Production guidelines, the government and the DHET should link the Primary Agriculture training to the land reform program where students can be trained under the land reform program.
- Full Text:
- Date Issued: 2016
Assessment of the implementation of the National Certificate (Vocational) plant production modules
- Langa, Phakama Perry Macmillan
- Authors: Langa, Phakama Perry Macmillan
- Date: 2016
- Subjects: Technical education -- Curricula Vocational education -- Curricula Curriculum planning
- Language: English
- Type: Thesis , Doctoral , Degree
- Identifier: http://hdl.handle.net/10353/5391 , vital:29229
- Description: This study investigates the implementation of Language in Education Policy (LiEP) in learning and teaching in grades six from two schools. It critically examines the teachers’ practices and experiences towards English as the language of learning and teaching (LoLT) at two different primary schools from the eMalahleni in the Lady Frere Education District in the Eastern Cape. The study is guided by the fact that most learners use their mother tongue (isiXhosa) in classroom as well as outside classroom contexts. Furthermore, some teachers use the translation method of teaching language as they code-switch to their home language when teaching content subjects as well as English. Despite this practice in class, learners are expected to answer their test and examination questions in English. Theoretically, this study is underpinned by the constructivist view of language learning (Gaserfeld, 2003) and English as an international language (Sivasubramaniam, 2011). On the basis of the ecological and the constructivist approaches to language learning, Sivasubramaniam (2011 p.53) views language as a creative instrument of meaning which ‘has the power to create meaning anew and afresh’ each time that someone uses it. The study makes use of the qualitative research method with a case study design that is placed within the interpretive paradigm. The data collected will be analysed through the use of critical discourse analysis. The findings from the study suggest some instrumental motivations to use English as LOLT which is informed by Language policy. Some of these motivations are: studying abroad, business with foreign investors and integrative motivations as the learner will be able to communicate with people from different countries. The study concludes that there is need for schools to stick to the English medium because this acts as an open door to the upward economic mobility among the previously disadvantaged. Based on this, it can be recommended that schools stick to English first additional language as their language of teaching and learning.
- Full Text:
- Date Issued: 2016
- Authors: Langa, Phakama Perry Macmillan
- Date: 2016
- Subjects: Technical education -- Curricula Vocational education -- Curricula Curriculum planning
- Language: English
- Type: Thesis , Doctoral , Degree
- Identifier: http://hdl.handle.net/10353/5391 , vital:29229
- Description: This study investigates the implementation of Language in Education Policy (LiEP) in learning and teaching in grades six from two schools. It critically examines the teachers’ practices and experiences towards English as the language of learning and teaching (LoLT) at two different primary schools from the eMalahleni in the Lady Frere Education District in the Eastern Cape. The study is guided by the fact that most learners use their mother tongue (isiXhosa) in classroom as well as outside classroom contexts. Furthermore, some teachers use the translation method of teaching language as they code-switch to their home language when teaching content subjects as well as English. Despite this practice in class, learners are expected to answer their test and examination questions in English. Theoretically, this study is underpinned by the constructivist view of language learning (Gaserfeld, 2003) and English as an international language (Sivasubramaniam, 2011). On the basis of the ecological and the constructivist approaches to language learning, Sivasubramaniam (2011 p.53) views language as a creative instrument of meaning which ‘has the power to create meaning anew and afresh’ each time that someone uses it. The study makes use of the qualitative research method with a case study design that is placed within the interpretive paradigm. The data collected will be analysed through the use of critical discourse analysis. The findings from the study suggest some instrumental motivations to use English as LOLT which is informed by Language policy. Some of these motivations are: studying abroad, business with foreign investors and integrative motivations as the learner will be able to communicate with people from different countries. The study concludes that there is need for schools to stick to the English medium because this acts as an open door to the upward economic mobility among the previously disadvantaged. Based on this, it can be recommended that schools stick to English first additional language as their language of teaching and learning.
- Full Text:
- Date Issued: 2016
Assessment of water quality based on diatom indices in a small temperate river system, Kowie River, South Africa
- Dalu, Tatenda, Bere, Taurai, Froneman, P William
- Authors: Dalu, Tatenda , Bere, Taurai , Froneman, P William
- Date: 2016
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/123896 , vital:35514 , http://dx.doi.org/10.4314/wsa.v42i2.02
- Description: This study aimed to assess the impact of land use patterns on water quality and benthic diatom community structure and to test the applicability of diatom indices developed in other regions of the world to a small temperate southern African river system. Sampling was conducted at eight study sites along the length of the river on four separate occasions. Multivariate data analyses were performed on the diatom community dataset to specify the main gradients of floristic variation and to detect and visualize similarities in diatom samples in relation to land-use patterns within the catchment. One hundred and twelve (112) diatom species belonging to 36 genera were recorded during the study. Canonical correspondence analysis (CCA) demonstrated that variations in the benthic diatom community structure were best explained by ammonium, nitrate, conductivity, pH, temperature, resistivity and water flow. OMNIDIA was used for calculation of selected diatom water quality indices. A number of the indices, e.g., the trophic diatom index (TDI), eutrophication/pollution index and biological index of water quality (BIWQ), either under- or over-estimated the water quality of the system. With few exceptions, there were no significant correlations (p> 0.05) between the diatom indices’ values and the nutrient variables. The absence of any significant correlations between the diatom indices’ values and selected physico-chemical variables suggests that indices developed in other regions of the world may not be suitable for temperate southern African rivers.
- Full Text:
- Date Issued: 2016
- Authors: Dalu, Tatenda , Bere, Taurai , Froneman, P William
- Date: 2016
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/123896 , vital:35514 , http://dx.doi.org/10.4314/wsa.v42i2.02
- Description: This study aimed to assess the impact of land use patterns on water quality and benthic diatom community structure and to test the applicability of diatom indices developed in other regions of the world to a small temperate southern African river system. Sampling was conducted at eight study sites along the length of the river on four separate occasions. Multivariate data analyses were performed on the diatom community dataset to specify the main gradients of floristic variation and to detect and visualize similarities in diatom samples in relation to land-use patterns within the catchment. One hundred and twelve (112) diatom species belonging to 36 genera were recorded during the study. Canonical correspondence analysis (CCA) demonstrated that variations in the benthic diatom community structure were best explained by ammonium, nitrate, conductivity, pH, temperature, resistivity and water flow. OMNIDIA was used for calculation of selected diatom water quality indices. A number of the indices, e.g., the trophic diatom index (TDI), eutrophication/pollution index and biological index of water quality (BIWQ), either under- or over-estimated the water quality of the system. With few exceptions, there were no significant correlations (p> 0.05) between the diatom indices’ values and the nutrient variables. The absence of any significant correlations between the diatom indices’ values and selected physico-chemical variables suggests that indices developed in other regions of the world may not be suitable for temperate southern African rivers.
- Full Text:
- Date Issued: 2016
Auditory processing problems within the inclusive foundation phase classroom: an exploration of teachers' experiences
- Authors: Deysel, Sanet
- Date: 2016
- Subjects: Inclusive education , Early childhood special education , Early childhood teachers
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: http://hdl.handle.net/10948/6834 , vital:21152
- Description: The Salamanca Statement (UNESCO, 1994) called upon all governments to implement inclusive education, ensuring that all learners with barriers to learning are included in the educational system. South Africa as a cosignatory to this global call responded with the implementation of the South African Education White Paper 6 (Department of Education, 2001) where the principles and foundations towards inclusive education were stipulated. It was expected of teachers to be able to accommodate learners with barriers to learning in their classrooms (Dednam, 2009, p. 371), although Ntombela and Green (2013, p. 2) state that teachers are not equipped to work with learners with specific disabilities. Learners present with various barriers to learning and these barriers pose problems and challenges in the classroom. One of these problems in the classroom is learners presenting with Auditory Processing Disorder. This qualitative study employed phenomenology as the research design. Through the use of memory work, drawings and focus group discussions as data production tools, the five Foundation Phase teachers’ experiences regarding learners presenting with Auditory Processing Disorder in the inclusive classroom, were explored. Bronfenbrenner’s ecological model was used to make meaning of the findings of the study. The findings of the study indicate that teachers are torn between the expectations of global and national policies regarding inclusive education and the management and support of learners presenting with Auditory Processing Disorder in their classrooms. Various challenges and problems arise with the inclusion of learners presenting with Auditory Processing Disorder in the classroom. The findings of the study were used to formulate guidelines to support Foundation Phase teachers working with learners presenting with auditory processing problems as well as policy suggestions for the Department of Basic Education. The Department of Basic Education should revise the implementation of CAPS to include the necessary adaptations for learners presenting with Auditory Processing Disorder; and also provide teacher assistants in Foundation Phase classrooms to enable the full inclusion of all learners.
- Full Text:
- Date Issued: 2016
- Authors: Deysel, Sanet
- Date: 2016
- Subjects: Inclusive education , Early childhood special education , Early childhood teachers
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: http://hdl.handle.net/10948/6834 , vital:21152
- Description: The Salamanca Statement (UNESCO, 1994) called upon all governments to implement inclusive education, ensuring that all learners with barriers to learning are included in the educational system. South Africa as a cosignatory to this global call responded with the implementation of the South African Education White Paper 6 (Department of Education, 2001) where the principles and foundations towards inclusive education were stipulated. It was expected of teachers to be able to accommodate learners with barriers to learning in their classrooms (Dednam, 2009, p. 371), although Ntombela and Green (2013, p. 2) state that teachers are not equipped to work with learners with specific disabilities. Learners present with various barriers to learning and these barriers pose problems and challenges in the classroom. One of these problems in the classroom is learners presenting with Auditory Processing Disorder. This qualitative study employed phenomenology as the research design. Through the use of memory work, drawings and focus group discussions as data production tools, the five Foundation Phase teachers’ experiences regarding learners presenting with Auditory Processing Disorder in the inclusive classroom, were explored. Bronfenbrenner’s ecological model was used to make meaning of the findings of the study. The findings of the study indicate that teachers are torn between the expectations of global and national policies regarding inclusive education and the management and support of learners presenting with Auditory Processing Disorder in their classrooms. Various challenges and problems arise with the inclusion of learners presenting with Auditory Processing Disorder in the classroom. The findings of the study were used to formulate guidelines to support Foundation Phase teachers working with learners presenting with auditory processing problems as well as policy suggestions for the Department of Basic Education. The Department of Basic Education should revise the implementation of CAPS to include the necessary adaptations for learners presenting with Auditory Processing Disorder; and also provide teacher assistants in Foundation Phase classrooms to enable the full inclusion of all learners.
- Full Text:
- Date Issued: 2016
A memory work project for Marikana
- Authors: Snyman, Emile Alexander
- Date: 2016
- Subjects: Monuments -- South Africa -- Rustenburg Memorials -- South Africa -- Rustenburg
- Language: English
- Type: Thesis , Masters , MArch
- Identifier: http://hdl.handle.net/10948/38885 , vital:35010
- Description: This treatise suggests one possible strategy for engaging the memory of the Marikana Massacre through different representational modes. Part 1 of this treatise takes the form of the research conducted, which was explorative in nature and focused on coming to an understanding of collective memory, the role of monuments and memorials within this process, the contemporary South African memorial landscape and the events that transpired at Marikana between 9 and 16 August 2012 and what their historical significance may be. As it was found that strikes featuring on the platinum belt were not only related to wage issues, Marikana as a settlement within the context of South Africa’s platinum belt was further investigated in order to highlight what the multiple challenges and issues are with which communities are faced on a daily basis. Part 2 sets out the strategy of a memory work project for Marikana which involves three components, namely a web- and phone-based application called ‘Remembering Marikana’ which provides a discursive arena for the politics of memory, a memorial for the victims of the Marikana Massacre at Thaba (Marikana Mountain) which facilitates annual commemoration of the massacre, and the design of a Mgcineni Noki Memorial Sports Centre, a community institution which embodies the values of the strike leaders and makes a positive contribution to the impoverished urban economy of the Wonderkop neighbourhood in Marikana.
- Full Text:
- Date Issued: 2016
- Authors: Snyman, Emile Alexander
- Date: 2016
- Subjects: Monuments -- South Africa -- Rustenburg Memorials -- South Africa -- Rustenburg
- Language: English
- Type: Thesis , Masters , MArch
- Identifier: http://hdl.handle.net/10948/38885 , vital:35010
- Description: This treatise suggests one possible strategy for engaging the memory of the Marikana Massacre through different representational modes. Part 1 of this treatise takes the form of the research conducted, which was explorative in nature and focused on coming to an understanding of collective memory, the role of monuments and memorials within this process, the contemporary South African memorial landscape and the events that transpired at Marikana between 9 and 16 August 2012 and what their historical significance may be. As it was found that strikes featuring on the platinum belt were not only related to wage issues, Marikana as a settlement within the context of South Africa’s platinum belt was further investigated in order to highlight what the multiple challenges and issues are with which communities are faced on a daily basis. Part 2 sets out the strategy of a memory work project for Marikana which involves three components, namely a web- and phone-based application called ‘Remembering Marikana’ which provides a discursive arena for the politics of memory, a memorial for the victims of the Marikana Massacre at Thaba (Marikana Mountain) which facilitates annual commemoration of the massacre, and the design of a Mgcineni Noki Memorial Sports Centre, a community institution which embodies the values of the strike leaders and makes a positive contribution to the impoverished urban economy of the Wonderkop neighbourhood in Marikana.
- Full Text:
- Date Issued: 2016
Back to the future: revival, relevance and route of an anarchist/syndicalist approach for twenty-first-century left, labour and national liberation movements
- Authors: van der Walt, Lucien
- Date: 2016
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/144812 , vital:38381 , DOI: 10.1080/02589001.2016.1235365
- Description: The failings of classical Marxism, social democracy and anti-imperialist nationalism point to the need for a radical left politics at a distance from the state. This paper examines the impact, revival and promise of the anarchist/syndicalist tradition, a rich, continuous praxis in labour, left, anti-imperialist, anti-racist and egalitarian movements, worldwide, since the 1860s. Outlining its core ideas – anti-hierarchy, anti-capitalism, anti-statism, opposition to social and economic inequality, internationalist class-based mobilisation – and critique of mainstream Marxism and nationalism, it highlights the arguments there is a basic incompatibility between state rule, and bottom-up, egalitarian, democratic, socialist relationships. The anarchist/syndicalist project cannot be reduced to an organising style, protest politics or spontaneism: for it, transition to a just, self-managed society requires organised popular capacity for a revolutionary rupture, developed through prefigurative, class-based, democratic organs of counter-power, including syndicalist unions aiming at collectivised property, and revolutionary counter-culture. Success needs formal organisation, unified strategy and anarchist / syndicalist political organisations.
- Full Text:
- Date Issued: 2016
- Authors: van der Walt, Lucien
- Date: 2016
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/144812 , vital:38381 , DOI: 10.1080/02589001.2016.1235365
- Description: The failings of classical Marxism, social democracy and anti-imperialist nationalism point to the need for a radical left politics at a distance from the state. This paper examines the impact, revival and promise of the anarchist/syndicalist tradition, a rich, continuous praxis in labour, left, anti-imperialist, anti-racist and egalitarian movements, worldwide, since the 1860s. Outlining its core ideas – anti-hierarchy, anti-capitalism, anti-statism, opposition to social and economic inequality, internationalist class-based mobilisation – and critique of mainstream Marxism and nationalism, it highlights the arguments there is a basic incompatibility between state rule, and bottom-up, egalitarian, democratic, socialist relationships. The anarchist/syndicalist project cannot be reduced to an organising style, protest politics or spontaneism: for it, transition to a just, self-managed society requires organised popular capacity for a revolutionary rupture, developed through prefigurative, class-based, democratic organs of counter-power, including syndicalist unions aiming at collectivised property, and revolutionary counter-culture. Success needs formal organisation, unified strategy and anarchist / syndicalist political organisations.
- Full Text:
- Date Issued: 2016
Bayesian accelerated life tests: exponential and Weibull models
- Authors: Izally, Sharkay Ruwade
- Date: 2016
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/3003 , vital:20351
- Description: Reliability life testing is used for life data analysis in which samples are tested under normal conditions to obtain failure time data for reliability assessment. It can be costly and time consuming to obtain failure time data under normal operating conditions if the mean time to failure of a product is long. An alternative is to use failure time data from an accelerated life test (ALT) to extrapolate the reliability under normal conditions. In accelerated life testing, the units are placed under a higher than normal stress condition such as voltage, current, pressure, temperature, to make the items fail in a shorter period of time. The failure information is then transformed through an accelerated model commonly known as the time transformation function, to predict the reliability under normal operating conditions. The power law will be used as the time transformation function in this thesis. We will first consider a Bayesian inference model under the assumption that the underlying life distribution in the accelerated life test is exponentially distributed. The maximal data information (MDI) prior, the Ghosh Mergel and Liu (GML) prior and the Jeffreys prior will be derived for the exponential distribution. The propriety of the posterior distributions will be investigated. Results will be compared when using these non-informative priors in a simulation study by looking at the posterior variances. The Weibull distribution as the underlying life distribution in the accelerated life test will also be investigated. The maximal data information prior will be derived for the Weibull distribution using the power law. The uniform prior and a mixture of Gamma and uniform priors will be considered. The propriety of these posteriors will also be investigated. The predictive reliability at the use-stress will be computed for these models. The deviance information criterion will be used to compare these priors. As a result of using a time transformation function, Bayesian inference becomes analytically intractable and Markov Chain Monte Carlo (MCMC) methods will be used to alleviate this problem. The Metropolis-Hastings algorithm will be used to sample from the posteriors for the exponential model in the accelerated life test. The adaptive rejection sampling method will be used to sample from the posterior distributions when the Weibull model is considered.
- Full Text:
- Date Issued: 2016
- Authors: Izally, Sharkay Ruwade
- Date: 2016
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/3003 , vital:20351
- Description: Reliability life testing is used for life data analysis in which samples are tested under normal conditions to obtain failure time data for reliability assessment. It can be costly and time consuming to obtain failure time data under normal operating conditions if the mean time to failure of a product is long. An alternative is to use failure time data from an accelerated life test (ALT) to extrapolate the reliability under normal conditions. In accelerated life testing, the units are placed under a higher than normal stress condition such as voltage, current, pressure, temperature, to make the items fail in a shorter period of time. The failure information is then transformed through an accelerated model commonly known as the time transformation function, to predict the reliability under normal operating conditions. The power law will be used as the time transformation function in this thesis. We will first consider a Bayesian inference model under the assumption that the underlying life distribution in the accelerated life test is exponentially distributed. The maximal data information (MDI) prior, the Ghosh Mergel and Liu (GML) prior and the Jeffreys prior will be derived for the exponential distribution. The propriety of the posterior distributions will be investigated. Results will be compared when using these non-informative priors in a simulation study by looking at the posterior variances. The Weibull distribution as the underlying life distribution in the accelerated life test will also be investigated. The maximal data information prior will be derived for the Weibull distribution using the power law. The uniform prior and a mixture of Gamma and uniform priors will be considered. The propriety of these posteriors will also be investigated. The predictive reliability at the use-stress will be computed for these models. The deviance information criterion will be used to compare these priors. As a result of using a time transformation function, Bayesian inference becomes analytically intractable and Markov Chain Monte Carlo (MCMC) methods will be used to alleviate this problem. The Metropolis-Hastings algorithm will be used to sample from the posteriors for the exponential model in the accelerated life test. The adaptive rejection sampling method will be used to sample from the posterior distributions when the Weibull model is considered.
- Full Text:
- Date Issued: 2016
Behaviour and trophic ecology of oceanic triggerfish (Canthidermis maculata) and rainbow runner (Elagatis bipinnulata) associated with floating objects in the open ocean
- Forget, Fabien Rocky Gilbert
- Authors: Forget, Fabien Rocky Gilbert
- Date: 2016
- Subjects: Uncatalogued
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/193531 , vital:45340
- Description: The oceanic triggerfish (Canthidermis maculata) and rainbow runner (Elagatis bipinnulata) are epipelagic species that commonly associate with floating objects throughout the world’s tropical oceans. Besides tunas, these two species often form the bulk of the aggregation and are major non-target species (bycatch) incidentally captured at fish aggregation devices (FADs) by tropical tuna purse seiners. Despite being abundant, little is known about their basic biology, ecology and associative behavior with floating objects. This thesis aims to address knowledge gaps in their associative behavior and ecology at floating objects and attempts to explore potential bycatch mitigation methods. Acoustic telemetry was used to characterise several aspects of the two species’ behavior at floating objects. Fish were captured and tagged at drifting FADs in the core of the western Indian Ocean tuna fishing grounds. Prolonged remote observations were obtained through satellite linked receivers which provided fine-scale data on the behavior of oceanic triggerfish (n= 46 919 cumulated observation days) and rainbow runner (n= 24 538 cumulated observation days). The two species remained associated with the same floating object for periods extending up to several months. The mean residence time estimated using a survival analysis was 65 days for oceanic triggerfish and 94 days for rainbow runner. A distinct diel pattern in association was observed; the two species were closely associated to the FAD during the night and increased their home range during the day while performing short excursions (oceanic triggerfish mean: 2.0 hours ±1.6 SD; rainbow runner mean: 2.4 hours ±2.2 SD) away from the FAD. Similarly, distinct patterns in the vertical movements and locomotory activity (measured using accelerometer tags) were observed as the two species increased their vertical movements and activity levels during the day. Generally, their vertical movements were largely restricted to the mixed layer (< 60 m). At night, the two species remained close to the surface (0-5 m) where they appear to be in a resting state. An interesting behavioural switch in activity levels and vertical distribution was observed for oceanic triggerfish which coincided with a change in the environment as the FAD drifted close to a cold-core cyclonic eddy. Ambient light appears to be the key stimulus triggering the observed diel behavioural patterns. species-specific vulnerability for target species, skipjack (Katsuwonus pelamis), yellowfin (Thunnus albacares), bigeye tuna (Thunnus obesus) and non-target species, including silky shark (Carcharhinus falciformis), oceanic triggerfish, and rainbow runner, to the purse seine fishing gear were investigated. Hourly presence rates at FADs over 24 hours were examined to assess whether the capture rate of non-target species could be reduced at specific times during the day. Silky sharks displayed a similar associative pattern to that of targeted tunas. Moreover, the vulnerability of both target and non-target species were close to the maximum during the period of behavioural transitions at sunrise when the majority of the fishing sets are made. As such, a change in set time in the western Indian Ocean does not appear to be a feasible method to reduce capture rates of non-target species. Stomach content and stable isotope analysis were conducted on oceanic triggerfish (stomach n = 152, isotope n = 65) and rainbow runner (stomach n = 156, isotope n = 71) incidentally captured individuals at FADs by purse seiners. Typical FAD-associated prey items represented a minor component of their diet as they predominantly foraged on zooplankton and micronekton in the water column, suggesting that oceanic triggerfish and rainbow runner do not associate to floating objects for direct trophic advantages. Overlap in their dietary and isotopic niches indicates an intermediate level of competition. Overall, the spatial and trophic ecology of both species are remarkably similar and prolonged associations with FADs indicates that floating objects play a significant ecological role in the pelagic environment for the two species. , Thesis (PhD) -- Faculty of Science, Ichthyology and Fisheries Science, 2016
- Full Text:
- Date Issued: 2016
- Authors: Forget, Fabien Rocky Gilbert
- Date: 2016
- Subjects: Uncatalogued
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/193531 , vital:45340
- Description: The oceanic triggerfish (Canthidermis maculata) and rainbow runner (Elagatis bipinnulata) are epipelagic species that commonly associate with floating objects throughout the world’s tropical oceans. Besides tunas, these two species often form the bulk of the aggregation and are major non-target species (bycatch) incidentally captured at fish aggregation devices (FADs) by tropical tuna purse seiners. Despite being abundant, little is known about their basic biology, ecology and associative behavior with floating objects. This thesis aims to address knowledge gaps in their associative behavior and ecology at floating objects and attempts to explore potential bycatch mitigation methods. Acoustic telemetry was used to characterise several aspects of the two species’ behavior at floating objects. Fish were captured and tagged at drifting FADs in the core of the western Indian Ocean tuna fishing grounds. Prolonged remote observations were obtained through satellite linked receivers which provided fine-scale data on the behavior of oceanic triggerfish (n= 46 919 cumulated observation days) and rainbow runner (n= 24 538 cumulated observation days). The two species remained associated with the same floating object for periods extending up to several months. The mean residence time estimated using a survival analysis was 65 days for oceanic triggerfish and 94 days for rainbow runner. A distinct diel pattern in association was observed; the two species were closely associated to the FAD during the night and increased their home range during the day while performing short excursions (oceanic triggerfish mean: 2.0 hours ±1.6 SD; rainbow runner mean: 2.4 hours ±2.2 SD) away from the FAD. Similarly, distinct patterns in the vertical movements and locomotory activity (measured using accelerometer tags) were observed as the two species increased their vertical movements and activity levels during the day. Generally, their vertical movements were largely restricted to the mixed layer (< 60 m). At night, the two species remained close to the surface (0-5 m) where they appear to be in a resting state. An interesting behavioural switch in activity levels and vertical distribution was observed for oceanic triggerfish which coincided with a change in the environment as the FAD drifted close to a cold-core cyclonic eddy. Ambient light appears to be the key stimulus triggering the observed diel behavioural patterns. species-specific vulnerability for target species, skipjack (Katsuwonus pelamis), yellowfin (Thunnus albacares), bigeye tuna (Thunnus obesus) and non-target species, including silky shark (Carcharhinus falciformis), oceanic triggerfish, and rainbow runner, to the purse seine fishing gear were investigated. Hourly presence rates at FADs over 24 hours were examined to assess whether the capture rate of non-target species could be reduced at specific times during the day. Silky sharks displayed a similar associative pattern to that of targeted tunas. Moreover, the vulnerability of both target and non-target species were close to the maximum during the period of behavioural transitions at sunrise when the majority of the fishing sets are made. As such, a change in set time in the western Indian Ocean does not appear to be a feasible method to reduce capture rates of non-target species. Stomach content and stable isotope analysis were conducted on oceanic triggerfish (stomach n = 152, isotope n = 65) and rainbow runner (stomach n = 156, isotope n = 71) incidentally captured individuals at FADs by purse seiners. Typical FAD-associated prey items represented a minor component of their diet as they predominantly foraged on zooplankton and micronekton in the water column, suggesting that oceanic triggerfish and rainbow runner do not associate to floating objects for direct trophic advantages. Overlap in their dietary and isotopic niches indicates an intermediate level of competition. Overall, the spatial and trophic ecology of both species are remarkably similar and prolonged associations with FADs indicates that floating objects play a significant ecological role in the pelagic environment for the two species. , Thesis (PhD) -- Faculty of Science, Ichthyology and Fisheries Science, 2016
- Full Text:
- Date Issued: 2016
Being a black mine worker in South Africa: the case of Anglo Platinum Mine
- Authors: Maseko, Robert
- Date: 2016
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/651 , vital:19978
- Description: This thesis presents a decolonial perspective on the experience of being a black mineworker in post-apartheid South Africa with specific reference to the Platinum Belt. It seeks to understand what it means to be a black mineworker by unmasking and analysing the existence and prevalence of coloniality in contemporary South Africa despite the end of formal colonialism (i.e. apartheid). As a world-wide system, coloniality has different dimensions which all speak to and highlight continuities between the period of colonialism and the post-colonial period. These dimensions are coloniality of power, coloniality of being and coloniality of knowledge. The power structure of coloniality produces and reproduces the identity of the black mineworker in present-day South Africa as a sub-ontological being devoid of an authentic humanity such that the mineworker is depicted as incapable of rational thought and knowledge. The existential condition of the black mineworker is symptomatic of the generic experience of being a racialised subject of colour in the current global power structure predicated on the dominance and hegemony of Western-centred modernity. The black mineworker exists on the darker side of Western-centred modernity, living a life of wretchedness and continuing to suffer the colonial wound in the absence of formal colonialism and apartheid. The mineworker is disposable and dispensable and lives and works in the shadow of death. In pursuing this course of reasoning, I deploy the epistemic method of ‘shifting the geography of reason’ in order to read the experience of mineworkers in South Africa from the locus of enunciation of the oppressed subject within the scheme of a colonial power differential based on a hierarchy of humanity. This method allows me to speak with and from the perspective of the black mineworkers in the Platinum Belt as opposed to speaking for and about them. I reach the conclusion that being a platinum mineworker in post-apartheid South Africa is a racial and market determined identity of colonialised subjectivity that relegates the dominated subject (the black mineworker) to the realm of the subhuman. In setting the context for this claim, I trace the origins and development of the black mineworker in South Africa with reference to historical processes such as dispossession and proletarianisation. Empirically, the thesis is rooted in a contemporary case study of mainly Anglo Platinum Mine, which involved comprehensive fieldwork focusing on the present lived realities of platinum mineworkers. The dignity and humanity of these black mineworkers has still not returned despite twenty years of democratic rule in South Africa, such that race remains a crucial organising principle in postapartheid South Africa.
- Full Text:
- Date Issued: 2016
- Authors: Maseko, Robert
- Date: 2016
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/651 , vital:19978
- Description: This thesis presents a decolonial perspective on the experience of being a black mineworker in post-apartheid South Africa with specific reference to the Platinum Belt. It seeks to understand what it means to be a black mineworker by unmasking and analysing the existence and prevalence of coloniality in contemporary South Africa despite the end of formal colonialism (i.e. apartheid). As a world-wide system, coloniality has different dimensions which all speak to and highlight continuities between the period of colonialism and the post-colonial period. These dimensions are coloniality of power, coloniality of being and coloniality of knowledge. The power structure of coloniality produces and reproduces the identity of the black mineworker in present-day South Africa as a sub-ontological being devoid of an authentic humanity such that the mineworker is depicted as incapable of rational thought and knowledge. The existential condition of the black mineworker is symptomatic of the generic experience of being a racialised subject of colour in the current global power structure predicated on the dominance and hegemony of Western-centred modernity. The black mineworker exists on the darker side of Western-centred modernity, living a life of wretchedness and continuing to suffer the colonial wound in the absence of formal colonialism and apartheid. The mineworker is disposable and dispensable and lives and works in the shadow of death. In pursuing this course of reasoning, I deploy the epistemic method of ‘shifting the geography of reason’ in order to read the experience of mineworkers in South Africa from the locus of enunciation of the oppressed subject within the scheme of a colonial power differential based on a hierarchy of humanity. This method allows me to speak with and from the perspective of the black mineworkers in the Platinum Belt as opposed to speaking for and about them. I reach the conclusion that being a platinum mineworker in post-apartheid South Africa is a racial and market determined identity of colonialised subjectivity that relegates the dominated subject (the black mineworker) to the realm of the subhuman. In setting the context for this claim, I trace the origins and development of the black mineworker in South Africa with reference to historical processes such as dispossession and proletarianisation. Empirically, the thesis is rooted in a contemporary case study of mainly Anglo Platinum Mine, which involved comprehensive fieldwork focusing on the present lived realities of platinum mineworkers. The dignity and humanity of these black mineworkers has still not returned despite twenty years of democratic rule in South Africa, such that race remains a crucial organising principle in postapartheid South Africa.
- Full Text:
- Date Issued: 2016
Being civil
- Matshoba, Zongezile Theophilus
- Authors: Matshoba, Zongezile Theophilus
- Date: 2016
- Language: English , Xhosa
- Type: Thesis , Masters , MA
- Identifier: vital:6017 , http://hdl.handle.net/10962/d1021237
- Description: My collection of short stories delves into government and governance, democracy, citizenship, civil servants, poverty, corruption and nepotism. My stories draw on the traditions of gritty urban crime fiction uncovering crimes of violence, service delivery, vandalism and corruption. They explore themes of mental cruelty and greed, self- preservation and community in rural areas, farms, townships and cities characterized by wrenching contradictions and inequalities. , This epic dramatic poetic verse delves into government and school governance, labour unions, liberation struggle, parenting and a wide range of school perceptions. It interrogates the roles of parents, teachers, students, department of education officials and that of other stakeholders that make use of schools. Influenced by William Wellington Gqoba’s ‘A great debate on education: a Parable’ wayback, it continues the education debate in the current post-democratic South Africa characterized by wrenching contradictions and inequalities. , This thesis is presented in two parts: English and isiXhosa.
- Full Text:
- Date Issued: 2016
- Authors: Matshoba, Zongezile Theophilus
- Date: 2016
- Language: English , Xhosa
- Type: Thesis , Masters , MA
- Identifier: vital:6017 , http://hdl.handle.net/10962/d1021237
- Description: My collection of short stories delves into government and governance, democracy, citizenship, civil servants, poverty, corruption and nepotism. My stories draw on the traditions of gritty urban crime fiction uncovering crimes of violence, service delivery, vandalism and corruption. They explore themes of mental cruelty and greed, self- preservation and community in rural areas, farms, townships and cities characterized by wrenching contradictions and inequalities. , This epic dramatic poetic verse delves into government and school governance, labour unions, liberation struggle, parenting and a wide range of school perceptions. It interrogates the roles of parents, teachers, students, department of education officials and that of other stakeholders that make use of schools. Influenced by William Wellington Gqoba’s ‘A great debate on education: a Parable’ wayback, it continues the education debate in the current post-democratic South Africa characterized by wrenching contradictions and inequalities. , This thesis is presented in two parts: English and isiXhosa.
- Full Text:
- Date Issued: 2016
Being for the Other: Surveillance and Depictions of Race, Gender, and Animals in Contemporary South African Fiction
- Authors: Laue, Kharys Ateh
- Date: 2016
- Language: English
- Type: Thesis , Masters , MA
- Identifier: http://hdl.handle.net/10962/3848 , vital:20549
- Description: This thesis examines the depiction, in contemporary South African fiction, of irresponsibility and responsibility in relation to the raced, gendered, and animal Other. Through a close analysis of Jeremy Bentham’s Panopticon prison and Michel Foucault’s study of this design, I establish the notion of disciplinary surveillance or panopticism. This I take to be a mode of power that seeks, by means of an invisible gaze, to render its subjects docile. In my readings of J. M. Coetzee’s Waiting for the Barbarians, Zoë Wicomb’s Playing in the Light, Justin Cartwright’s White Lightning, and selected short stories from Wicomb’s You Can’t Get Lost in Cape Town and The One That Got Away, I demonstrate that oppressive authoritarian regimes are rooted in Benthamic principles of hyper-visibility and concealment. Disciplinary power, I contend, is effective precisely because it places an individual in a constant state of Being-for-Others, a term coined by Jean-Paul Sartre to describe the experience of objectification through another’s look. Judith Butler’s concept of gender performativity and W. E. B. Du Bois’s notion of black double consciousness frame my examination of, respectively, gender and racial oppression, while my discussion of animals appeals to Jacques Derrida’s work on the non-human. I show how surveillance, in each of the selected texts, functions through a racist and/or sexist and/or speciesist gaze that facilitates violent, irresponsible relationships with the human and non-human Other. The texts under discussion, however, also depict ways in which the Other actively resists and subverts regimes of oppression, often by means of a counter gaze that compels the protagonist, or the reader, to take up responsibility for Others. Ultimately, my study concludes that the fictional works of Coetzee, Wicomb, and Cartwright offer an ethics of empathetic responsibility, which I term Being for the Other, in opposition to mechanisms of disciplinary surveillance that seek to oppress, conceal, and dominate.
- Full Text:
- Date Issued: 2016
- Authors: Laue, Kharys Ateh
- Date: 2016
- Language: English
- Type: Thesis , Masters , MA
- Identifier: http://hdl.handle.net/10962/3848 , vital:20549
- Description: This thesis examines the depiction, in contemporary South African fiction, of irresponsibility and responsibility in relation to the raced, gendered, and animal Other. Through a close analysis of Jeremy Bentham’s Panopticon prison and Michel Foucault’s study of this design, I establish the notion of disciplinary surveillance or panopticism. This I take to be a mode of power that seeks, by means of an invisible gaze, to render its subjects docile. In my readings of J. M. Coetzee’s Waiting for the Barbarians, Zoë Wicomb’s Playing in the Light, Justin Cartwright’s White Lightning, and selected short stories from Wicomb’s You Can’t Get Lost in Cape Town and The One That Got Away, I demonstrate that oppressive authoritarian regimes are rooted in Benthamic principles of hyper-visibility and concealment. Disciplinary power, I contend, is effective precisely because it places an individual in a constant state of Being-for-Others, a term coined by Jean-Paul Sartre to describe the experience of objectification through another’s look. Judith Butler’s concept of gender performativity and W. E. B. Du Bois’s notion of black double consciousness frame my examination of, respectively, gender and racial oppression, while my discussion of animals appeals to Jacques Derrida’s work on the non-human. I show how surveillance, in each of the selected texts, functions through a racist and/or sexist and/or speciesist gaze that facilitates violent, irresponsible relationships with the human and non-human Other. The texts under discussion, however, also depict ways in which the Other actively resists and subverts regimes of oppression, often by means of a counter gaze that compels the protagonist, or the reader, to take up responsibility for Others. Ultimately, my study concludes that the fictional works of Coetzee, Wicomb, and Cartwright offer an ethics of empathetic responsibility, which I term Being for the Other, in opposition to mechanisms of disciplinary surveillance that seek to oppress, conceal, and dominate.
- Full Text:
- Date Issued: 2016
Benzoyl isothiocyanates derived ligands as potential HIV-1 protease inhibitors and their reactions with gold ions
- Authors: Odame, Felix
- Date: 2016
- Subjects: HIV (Viruses) -- Enzymes Enzyme inhibitors -- Research , Pharmaceutical chemistry Biochemistry
- Language: English
- Type: Thesis , Doctoral , DPhil
- Identifier: http://hdl.handle.net/10948/33228 , vital:32585
- Description: The synthesis and evaluation of benzoyl isothiocyanate derivatives as potential HIV-1 protease inhibitors is presented. The ligands were first designed to fit the protease active site using Autodock 4.2. The design was based on the deNOVO method of drug design in which the active site coordinates from the crystal structure of protease bound to ritonavir was used. An attempt to access the scaffolds designed initially led to the formation of 2,2,4-trimethyl 2,3-dihydro-1H-1,5-benzodiazepin-5-ium isophthalate and 2-2-(3-methylphenyl-1Hbenzimidazole which could not be converted to the desired intermediate. A further attempt led to formation of amino acid and amino acid ester derivatives of benzoyl isothiocyanates which have been fully characterized and the reasons why the desired intermediates were not readily accessible explained. Scaffolds based on the benzoyl isothiocyanate derivatives of structurally diverse diamines were then screened. Sixty compounds have been synthesized and fully characterized using elemental analysis, spectroscopy, GC-MS and twenty-six crystal structures have been discussed. The DFT transition state studies of 11-phenyl- 1,8,10,12-tetraazatricyclo[7.4.0.02,7]trideca-2(7),3,5,9,11-pentaene-13-thione (20), N-(1Hbenzimidazol-2-yl)benzamide (21), 3-(1,3-benzothiazol-2-yl)-1-(benzoyl)thiourea (23), and N-[(9E)-8,10,17-triazatetracyclo[8.7.0.02,7.011,16]heptadeca-1(17),2,4,6,11(16),12,14-heptaen-9-ylidene] benzamide (39), have been carried out and their detailed density functional theory reaction mechanism have be computed. The Bernly algorithm was used in the determination of saddle points (transtions states), and the intrinsic reaction coordinates leading to the determination of intermediates were traced and optimized to a global minimum or in some cases a local minimum was obtained. The cell viability tests of diamine derivatives which was done by exposing white blood cells to the compounds (inhibitors) at 37 °C and a pH of 7.4 showed that 1-(4-bromobenzoyl)-3-[2- ({[(4-bromophenyl)formamido]methanethioyl}amino)phenyl]thiourea (46), 1-(3-chloro benzoyl)-3-[2-({[(3-chlorophenyl)formamido]methanethioyl}amino)phenyl]thiourea (48), 1- (3-bromobenzoyl)-3-[2-({[(3-bromophenyl)formamido]methanethioyl}amino)phenyl] thiourea (49) and 3-benzoyl-1-(4-{[(phenylformamido)methanethioyl]amino}butyl)thiourea (54), in that group of compounds were cytotoxic with EC50 values of 17.04 ± 9.75 μM, 69.20± 38.16 μM, 35.90 ± 20.55 μM and 68.37 ± 26.45 μM, respectively. 4-Bromo-N-[(9E)-8,10,17-triazatetracyclo[8.7.0.02,7.011,16]heptadeca-1(17),2,4,6,11(16),12,14-heptaen-9-ylidene] benzamide (32), 4-methoxy-N-[(9E)-8,10,17-triazatetracyclo[8.7.0.02,7.011,16]heptadeca-1(17),2,4,6,11(16),12,14-heptaen-9-ylidene]benzamide (33) and 3-chloro-N-[(9E)-8,10,17-triazatetracyclo[8.7.0.02,7.011,16]heptadeca-1(17),2,4,6,11(16),12,14-heptaen-9-ylidene] benzamide (37) were also cytotoxic giving EC50 values of 45.47 ± 21.92, 45.09 ±13.79 and 74.94 ± 13.17 μM, respectively. 3-(1,3-Benzothiazol-2-yl)-1-(3-bromobenzoyl)thiourea (31) and 3-(1,3-benzothiazoyl-2-yl)-1-(4-nitrobenzoyl)thiourea (30) derivatives were also found to be cytotoxic with EC50 values of 1.207 ± 0.58 and 24.08 ±13.14 nM, respectively. 11-(4-Chlorophenyl-1,8,10, 12-tetraazatricyclo[7.4.0.02,7]trideca-2(7),3,5,9,11-pentaene-13-thione (12), 11-(4-methoxyphenyl)-1,8,10,12-tetraazatricyclo[7.4.0.02,7]trideca-2(7),3,9,1-pentaene-13-thione (14), and 11-phenyl-1,8,10,12-tetraazatricyclo[7.4.0.02,7]trideca-2(7),3,5,9,11-pentaene-13-thione (20), were found to be cytotoxic giving EC50 values of 0.152 ± 0.051, 37.96 ± 21.87 and 5.28 ± 2.95 μM, respectively. In the enzyme inhibition studies compound 49 gave a percentage inhibition of 97.03 ± 10.61% at 100 μM, but the fact that it is cytoxic might make it less useful, whilst compounds 19 and 16 had a percentage inhibition of 59.57 ± 13.59% (4-nitro derivative) and 79.97 ± 11.97% (3-nitro derivative) respectively at 100 μM of inhibitor and 20 μM of enzyme (HIV-1 protease). The results suggests that the presence of the nitro group at position 3 (16) and 4 (19) leads to an increase in activity against HIV-1 protease.
- Full Text:
- Date Issued: 2016
- Authors: Odame, Felix
- Date: 2016
- Subjects: HIV (Viruses) -- Enzymes Enzyme inhibitors -- Research , Pharmaceutical chemistry Biochemistry
- Language: English
- Type: Thesis , Doctoral , DPhil
- Identifier: http://hdl.handle.net/10948/33228 , vital:32585
- Description: The synthesis and evaluation of benzoyl isothiocyanate derivatives as potential HIV-1 protease inhibitors is presented. The ligands were first designed to fit the protease active site using Autodock 4.2. The design was based on the deNOVO method of drug design in which the active site coordinates from the crystal structure of protease bound to ritonavir was used. An attempt to access the scaffolds designed initially led to the formation of 2,2,4-trimethyl 2,3-dihydro-1H-1,5-benzodiazepin-5-ium isophthalate and 2-2-(3-methylphenyl-1Hbenzimidazole which could not be converted to the desired intermediate. A further attempt led to formation of amino acid and amino acid ester derivatives of benzoyl isothiocyanates which have been fully characterized and the reasons why the desired intermediates were not readily accessible explained. Scaffolds based on the benzoyl isothiocyanate derivatives of structurally diverse diamines were then screened. Sixty compounds have been synthesized and fully characterized using elemental analysis, spectroscopy, GC-MS and twenty-six crystal structures have been discussed. The DFT transition state studies of 11-phenyl- 1,8,10,12-tetraazatricyclo[7.4.0.02,7]trideca-2(7),3,5,9,11-pentaene-13-thione (20), N-(1Hbenzimidazol-2-yl)benzamide (21), 3-(1,3-benzothiazol-2-yl)-1-(benzoyl)thiourea (23), and N-[(9E)-8,10,17-triazatetracyclo[8.7.0.02,7.011,16]heptadeca-1(17),2,4,6,11(16),12,14-heptaen-9-ylidene] benzamide (39), have been carried out and their detailed density functional theory reaction mechanism have be computed. The Bernly algorithm was used in the determination of saddle points (transtions states), and the intrinsic reaction coordinates leading to the determination of intermediates were traced and optimized to a global minimum or in some cases a local minimum was obtained. The cell viability tests of diamine derivatives which was done by exposing white blood cells to the compounds (inhibitors) at 37 °C and a pH of 7.4 showed that 1-(4-bromobenzoyl)-3-[2- ({[(4-bromophenyl)formamido]methanethioyl}amino)phenyl]thiourea (46), 1-(3-chloro benzoyl)-3-[2-({[(3-chlorophenyl)formamido]methanethioyl}amino)phenyl]thiourea (48), 1- (3-bromobenzoyl)-3-[2-({[(3-bromophenyl)formamido]methanethioyl}amino)phenyl] thiourea (49) and 3-benzoyl-1-(4-{[(phenylformamido)methanethioyl]amino}butyl)thiourea (54), in that group of compounds were cytotoxic with EC50 values of 17.04 ± 9.75 μM, 69.20± 38.16 μM, 35.90 ± 20.55 μM and 68.37 ± 26.45 μM, respectively. 4-Bromo-N-[(9E)-8,10,17-triazatetracyclo[8.7.0.02,7.011,16]heptadeca-1(17),2,4,6,11(16),12,14-heptaen-9-ylidene] benzamide (32), 4-methoxy-N-[(9E)-8,10,17-triazatetracyclo[8.7.0.02,7.011,16]heptadeca-1(17),2,4,6,11(16),12,14-heptaen-9-ylidene]benzamide (33) and 3-chloro-N-[(9E)-8,10,17-triazatetracyclo[8.7.0.02,7.011,16]heptadeca-1(17),2,4,6,11(16),12,14-heptaen-9-ylidene] benzamide (37) were also cytotoxic giving EC50 values of 45.47 ± 21.92, 45.09 ±13.79 and 74.94 ± 13.17 μM, respectively. 3-(1,3-Benzothiazol-2-yl)-1-(3-bromobenzoyl)thiourea (31) and 3-(1,3-benzothiazoyl-2-yl)-1-(4-nitrobenzoyl)thiourea (30) derivatives were also found to be cytotoxic with EC50 values of 1.207 ± 0.58 and 24.08 ±13.14 nM, respectively. 11-(4-Chlorophenyl-1,8,10, 12-tetraazatricyclo[7.4.0.02,7]trideca-2(7),3,5,9,11-pentaene-13-thione (12), 11-(4-methoxyphenyl)-1,8,10,12-tetraazatricyclo[7.4.0.02,7]trideca-2(7),3,9,1-pentaene-13-thione (14), and 11-phenyl-1,8,10,12-tetraazatricyclo[7.4.0.02,7]trideca-2(7),3,5,9,11-pentaene-13-thione (20), were found to be cytotoxic giving EC50 values of 0.152 ± 0.051, 37.96 ± 21.87 and 5.28 ± 2.95 μM, respectively. In the enzyme inhibition studies compound 49 gave a percentage inhibition of 97.03 ± 10.61% at 100 μM, but the fact that it is cytoxic might make it less useful, whilst compounds 19 and 16 had a percentage inhibition of 59.57 ± 13.59% (4-nitro derivative) and 79.97 ± 11.97% (3-nitro derivative) respectively at 100 μM of inhibitor and 20 μM of enzyme (HIV-1 protease). The results suggests that the presence of the nitro group at position 3 (16) and 4 (19) leads to an increase in activity against HIV-1 protease.
- Full Text:
- Date Issued: 2016
Beta decay of 100/400 Zr produced in neutron-induced fission of natural uranium
- Authors: Kamoto, Thokozani
- Date: 2016
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/3024 , vital:20353
- Description: Fission fragments, produced by neutron bombardment of natural uranium at the Physics Department, Jyväskylä, Finland, are studied in this work. The data had been sorted into 25 Y — y coincidence matrices which were then analysed. In this work we aimed to identify the fission products using Y-Y coincidence analysis and then study the beta-decay of some of the fission products. Sixteen fission products ranging from A = 94 to A = 136 were identified. Out of these fission products beta decay of the A = 100 (100/40 Zr – 100/41 Nb – 100/42 Mo) chain was studied in greater detail. We have also studied the variation of the relative intensities as a function of time of the 159-, 528-, 600-, 768-, 928- and 1502-keV Y-rav lines in 100/42 Mo and the profiles of the relative intensities have been modelled with the variation of the activity of 100/41 Nb against time. Configuration assignments of 100 Zr and 100/42 Mo are discussed.
- Full Text:
- Date Issued: 2016
- Authors: Kamoto, Thokozani
- Date: 2016
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/3024 , vital:20353
- Description: Fission fragments, produced by neutron bombardment of natural uranium at the Physics Department, Jyväskylä, Finland, are studied in this work. The data had been sorted into 25 Y — y coincidence matrices which were then analysed. In this work we aimed to identify the fission products using Y-Y coincidence analysis and then study the beta-decay of some of the fission products. Sixteen fission products ranging from A = 94 to A = 136 were identified. Out of these fission products beta decay of the A = 100 (100/40 Zr – 100/41 Nb – 100/42 Mo) chain was studied in greater detail. We have also studied the variation of the relative intensities as a function of time of the 159-, 528-, 600-, 768-, 928- and 1502-keV Y-rav lines in 100/42 Mo and the profiles of the relative intensities have been modelled with the variation of the activity of 100/41 Nb against time. Configuration assignments of 100 Zr and 100/42 Mo are discussed.
- Full Text:
- Date Issued: 2016
Between sentences
- Authors: Thesen, Jo-Ann
- Date: 2016
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:6007 , http://hdl.handle.net/10962/1021215
- Description: My stories explore different forms, including flash fiction. Some use the fairy tale form to combine fiction and non-fiction in order to reach the essence of the story. In this I am influenced by Kate Bernheimer, who speaks of the “flatness, abstraction, intuitive logic and normalized magic” of traditional fairy tales. A number of stories are set in the places I worked as a newspaper reporter. Here I use my old press reports as starting points for the real or imagined story behind the news – often involving miscommunication, dominance, exploitation, the tension between isolation and belonging, and the nuances of family relationships.
- Full Text:
- Date Issued: 2016
- Authors: Thesen, Jo-Ann
- Date: 2016
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:6007 , http://hdl.handle.net/10962/1021215
- Description: My stories explore different forms, including flash fiction. Some use the fairy tale form to combine fiction and non-fiction in order to reach the essence of the story. In this I am influenced by Kate Bernheimer, who speaks of the “flatness, abstraction, intuitive logic and normalized magic” of traditional fairy tales. A number of stories are set in the places I worked as a newspaper reporter. Here I use my old press reports as starting points for the real or imagined story behind the news – often involving miscommunication, dominance, exploitation, the tension between isolation and belonging, and the nuances of family relationships.
- Full Text:
- Date Issued: 2016
Between"culture" and "Cruelty"narratives of widows on land dispossession in Gqadu administrative area, Mbashe Municipality , Eastern Cape
- Authors: Baleka, Zola
- Date: 2016
- Subjects: Widows -- South Africa -- Eastern Cape Land tenure -- South Africa -- Eastern Cape Right of property -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Masters , Degree
- Identifier: http://hdl.handle.net/10353/5083 , vital:29057
- Description: This study highlights the cultural underpinnings of specific indulgences pertaining to land ownership with reference to widowhood in the rural Eastern Cape. The study does this by examining the narratives of widows about their experiences of land dispossession in Nqadu Administrative Area. Nqadu Administrative Area is a rural community in Mbhashe Local Municipality in the Eastern Cape Province of South Africa. The study focuses on widows’ experiences relating to the cultural practices of the community regarding land ownership. A qualitative, case study design was adopted. To uncover the widows’ narratives, the study utilised in-depth interviews and focus group discussions, with a sample of 50 widows. Further empirical data were obtained from four members of the municipal Land Committees, two Ward Councillors, four Traditional Leaders and two officials from the Eastern Cape Department of Rural Development and Agrarian Reform, using in-depth and key informant interviews. The study found that widows were vulnerable to land ownership violations and dispossessions, and that these violations were perpetrated by community members, particularly relatives of deceased husbands. Low levels of education and fear of antagonising clan relatives played a vital role in preventing widows from fighting for their legal rights. The failure of widows to fight for their rights increased their chances of being heavily exposed to dispossession of their land rights. Cultural practices within the communities catalysed abusive practices against widows, particularly against those whose marriage was not ‘recognised’ due to various stated reasons. The study also revealed that widows who had married as second wives and those who did not bear children experienced egregious abuses. Another finding was that men from Nqadu Administrative Area were given priority during the allocation of land, based on cultural and traditional practices, and were given land of their own choice depending on availability. The study thus highlights the impact of cultural practices and the ways in which these became instruments of gender abuse, despite the existence of laws designed to prevent specific social cruelties.
- Full Text:
- Date Issued: 2016
- Authors: Baleka, Zola
- Date: 2016
- Subjects: Widows -- South Africa -- Eastern Cape Land tenure -- South Africa -- Eastern Cape Right of property -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Masters , Degree
- Identifier: http://hdl.handle.net/10353/5083 , vital:29057
- Description: This study highlights the cultural underpinnings of specific indulgences pertaining to land ownership with reference to widowhood in the rural Eastern Cape. The study does this by examining the narratives of widows about their experiences of land dispossession in Nqadu Administrative Area. Nqadu Administrative Area is a rural community in Mbhashe Local Municipality in the Eastern Cape Province of South Africa. The study focuses on widows’ experiences relating to the cultural practices of the community regarding land ownership. A qualitative, case study design was adopted. To uncover the widows’ narratives, the study utilised in-depth interviews and focus group discussions, with a sample of 50 widows. Further empirical data were obtained from four members of the municipal Land Committees, two Ward Councillors, four Traditional Leaders and two officials from the Eastern Cape Department of Rural Development and Agrarian Reform, using in-depth and key informant interviews. The study found that widows were vulnerable to land ownership violations and dispossessions, and that these violations were perpetrated by community members, particularly relatives of deceased husbands. Low levels of education and fear of antagonising clan relatives played a vital role in preventing widows from fighting for their legal rights. The failure of widows to fight for their rights increased their chances of being heavily exposed to dispossession of their land rights. Cultural practices within the communities catalysed abusive practices against widows, particularly against those whose marriage was not ‘recognised’ due to various stated reasons. The study also revealed that widows who had married as second wives and those who did not bear children experienced egregious abuses. Another finding was that men from Nqadu Administrative Area were given priority during the allocation of land, based on cultural and traditional practices, and were given land of their own choice depending on availability. The study thus highlights the impact of cultural practices and the ways in which these became instruments of gender abuse, despite the existence of laws designed to prevent specific social cruelties.
- Full Text:
- Date Issued: 2016
Beyond commercial design: a critique of design and graphic design writings in Emigre and Dot Dot Dot magazines
- Authors: Muir, Margot
- Date: 2016
- Subjects: Graphic design (Typography) Graphic arts Magazine design
- Language: English
- Type: Thesis , Masters , MA
- Identifier: http://hdl.handle.net/10948/12436 , vital:27066
- Description: Graphic design faces the contradictions of commercial intent and social relevance. This study explores the contribution of criticism, in two independent, seminal graphic design magazines, towards shifting the dominant preferences of graphic design from a purely commercial pursuit to a human-centred practice. Emigre magazine (c.1984 - 2005) and Dot Dot Dot magazine (c.2000 - 2010) are recognised for their critical intent and within them are emerging critical issues that suggest a potential niche for graphic design beyond consumerism and commerce. In the discipline of graphic design, designers define what it is to be human (and thus equally the realities of dehumanisation) in very particular ways (Rose, 2001:135; Freire, 1993:43). Graphic design has a history of commercial practice. This commercial history continues to define its identity and reinforce a particular body of knowledge. Graphic design criticism, however, is an inventive voice that has the potential to contribute to change. Both Emigre and Dot Dot Dot were representative of a “constructive marginality” (Bennett, 1993:64), drawing from their own set of references and awareness of graphic design’s potential to inform their identities, instead of looking to established definitions of practice to do so. This analysis explores how they anticipated a modern conception of graphic design that has become part of a recently adopted (2015) and more widely embedded discourse. This discourse involves critical design that interrogates multiculturalism, interdisciplinarity, environmental sustainability, social and political agency, and speculative futures. Graphic design engages social institutions and practices that denote social constructions of difference and inequality, and is never neutral. Any work, any representation of ideology, is at once individual and discursive at the level of social, cultural and political formations. The critical issues evident in Emigre and Dot Dot Dot, with the exception of an absence of speculative futures, anticipate a more humanising perspective in graphic design. They invite critique and the potential for change that is relevant to the surrounding world, as a counter to commercial self-interest.
- Full Text:
- Date Issued: 2016
- Authors: Muir, Margot
- Date: 2016
- Subjects: Graphic design (Typography) Graphic arts Magazine design
- Language: English
- Type: Thesis , Masters , MA
- Identifier: http://hdl.handle.net/10948/12436 , vital:27066
- Description: Graphic design faces the contradictions of commercial intent and social relevance. This study explores the contribution of criticism, in two independent, seminal graphic design magazines, towards shifting the dominant preferences of graphic design from a purely commercial pursuit to a human-centred practice. Emigre magazine (c.1984 - 2005) and Dot Dot Dot magazine (c.2000 - 2010) are recognised for their critical intent and within them are emerging critical issues that suggest a potential niche for graphic design beyond consumerism and commerce. In the discipline of graphic design, designers define what it is to be human (and thus equally the realities of dehumanisation) in very particular ways (Rose, 2001:135; Freire, 1993:43). Graphic design has a history of commercial practice. This commercial history continues to define its identity and reinforce a particular body of knowledge. Graphic design criticism, however, is an inventive voice that has the potential to contribute to change. Both Emigre and Dot Dot Dot were representative of a “constructive marginality” (Bennett, 1993:64), drawing from their own set of references and awareness of graphic design’s potential to inform their identities, instead of looking to established definitions of practice to do so. This analysis explores how they anticipated a modern conception of graphic design that has become part of a recently adopted (2015) and more widely embedded discourse. This discourse involves critical design that interrogates multiculturalism, interdisciplinarity, environmental sustainability, social and political agency, and speculative futures. Graphic design engages social institutions and practices that denote social constructions of difference and inequality, and is never neutral. Any work, any representation of ideology, is at once individual and discursive at the level of social, cultural and political formations. The critical issues evident in Emigre and Dot Dot Dot, with the exception of an absence of speculative futures, anticipate a more humanising perspective in graphic design. They invite critique and the potential for change that is relevant to the surrounding world, as a counter to commercial self-interest.
- Full Text:
- Date Issued: 2016
Bio-prospecting a Soil Metagenomic Library for Carbohydrate Active Esterases
- Authors: Shezi, Ntombifuthi
- Date: 2016
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4172 , http://hdl.handle.net/10962/d1021266
- Description: Lignocellulosic biomass is a promising renewable resource on earth. Plant biomass contains fermentable sugars and other moieties that can be converted to biofuels or other chemicals. Enzymatic hydrolysis of these biopolymers is significant in the liberation of sugars for fermentation into desired products. Owing to its complex structure, synergistic action of enzymes is required for its degradation. Enzymes that are involved in biomass degradation include cellulases, hemicellulases and the accessory enzymes acetyl xylan esterases and ferulic acid esterases. Ferulic acid esterases (FAEs, EC 3.1.1.73), represent a subclass of carboxylester hydrolases (EC 3.1.1.-) that catalyse the release of hydroxycinnamic acids (such as ferulic acid, p-coumaric, ferulic, sinapic and caffeic acid) that are generally found esterified to polysaccharides, such as arabinoxylans. Hydroxycinnamic acids have widespread potential applications due to their antimicrobial, photoprotectant and antioxidant properties, as well as their use as flavour precursors. Therefore, this interesting group of FAEs has a potentially wide variety of applications in agriculture, food and pharmaceutical industries. In the search for novel biocatalysts, metagenomics is considered as an alternative approach to conventional microbe screening, therefore, searching for novel biocatalysts from a soil metagenome that harbours a unique diversity of biocatalyst is significant. The aim of this study was to extract DNA from soil associated with cattle manure and construct a soil metagenomic library using a fosmid based plasmid vector and subsequently functionally screen for ferulic acid esterases using ethyl ferulate as a model substrate. A total of 59 recombinant fosmids conferring ferulic acid esterase phenotypes were identified (Hit rate 1:3122) and the two fosmids that consistently showed high FAE activities were selected for further study. Following nucleotide sequencing and translational analysis, two fae encoding open reading frames (FAE9 and FAE27) of approximately 274 and 322 aa, respectively, were identified. The amino acid sequence of the two ORFs contained a classical conserved esterase/lipase G-x-S-x-G sequence motif. The two genes (fae9 and fae27) were successfully expressed in Escherichia coli BL21 (DE3) and the purified enzymes exhibited respective temperature optima of 50 °C and 40 °C, and respective pH optima of 6.0 and 7.0. Further biochemical characterisation showed that FAE9 and FAE27 have high substrate specificity, following the fact that EFA is the preferred substrate for FAE9 (kcat/Km value of 128 s−1.mM-1) and also the preferred substrate for FAE27 (kcat/Km value of 137 s−1.mM-1). This work proves that soil is a valuable environmental source for novel esterase screening through functional based metagenomic approach. Therefore, this method may be used to screen for other valuable enzymes from environmental sources using inexpensive natural sources to encourage the screening of specific enzymes. Biochemistry of the two isolated enzymes makes these enzymes to be useful in industrial applications due to broad substrate activity that could replace the specialised enzymes to complete plant biomass degradation.
- Full Text:
- Date Issued: 2016
- Authors: Shezi, Ntombifuthi
- Date: 2016
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4172 , http://hdl.handle.net/10962/d1021266
- Description: Lignocellulosic biomass is a promising renewable resource on earth. Plant biomass contains fermentable sugars and other moieties that can be converted to biofuels or other chemicals. Enzymatic hydrolysis of these biopolymers is significant in the liberation of sugars for fermentation into desired products. Owing to its complex structure, synergistic action of enzymes is required for its degradation. Enzymes that are involved in biomass degradation include cellulases, hemicellulases and the accessory enzymes acetyl xylan esterases and ferulic acid esterases. Ferulic acid esterases (FAEs, EC 3.1.1.73), represent a subclass of carboxylester hydrolases (EC 3.1.1.-) that catalyse the release of hydroxycinnamic acids (such as ferulic acid, p-coumaric, ferulic, sinapic and caffeic acid) that are generally found esterified to polysaccharides, such as arabinoxylans. Hydroxycinnamic acids have widespread potential applications due to their antimicrobial, photoprotectant and antioxidant properties, as well as their use as flavour precursors. Therefore, this interesting group of FAEs has a potentially wide variety of applications in agriculture, food and pharmaceutical industries. In the search for novel biocatalysts, metagenomics is considered as an alternative approach to conventional microbe screening, therefore, searching for novel biocatalysts from a soil metagenome that harbours a unique diversity of biocatalyst is significant. The aim of this study was to extract DNA from soil associated with cattle manure and construct a soil metagenomic library using a fosmid based plasmid vector and subsequently functionally screen for ferulic acid esterases using ethyl ferulate as a model substrate. A total of 59 recombinant fosmids conferring ferulic acid esterase phenotypes were identified (Hit rate 1:3122) and the two fosmids that consistently showed high FAE activities were selected for further study. Following nucleotide sequencing and translational analysis, two fae encoding open reading frames (FAE9 and FAE27) of approximately 274 and 322 aa, respectively, were identified. The amino acid sequence of the two ORFs contained a classical conserved esterase/lipase G-x-S-x-G sequence motif. The two genes (fae9 and fae27) were successfully expressed in Escherichia coli BL21 (DE3) and the purified enzymes exhibited respective temperature optima of 50 °C and 40 °C, and respective pH optima of 6.0 and 7.0. Further biochemical characterisation showed that FAE9 and FAE27 have high substrate specificity, following the fact that EFA is the preferred substrate for FAE9 (kcat/Km value of 128 s−1.mM-1) and also the preferred substrate for FAE27 (kcat/Km value of 137 s−1.mM-1). This work proves that soil is a valuable environmental source for novel esterase screening through functional based metagenomic approach. Therefore, this method may be used to screen for other valuable enzymes from environmental sources using inexpensive natural sources to encourage the screening of specific enzymes. Biochemistry of the two isolated enzymes makes these enzymes to be useful in industrial applications due to broad substrate activity that could replace the specialised enzymes to complete plant biomass degradation.
- Full Text:
- Date Issued: 2016
Biocomposites from polyfurfuryl alcohol reinforced with microfibres and nanocellulose from flax fibres and maize stalks
- Mtibe, Asanda, Linganiso, Linda
- Authors: Mtibe, Asanda , Linganiso, Linda
- Date: 2016
- Subjects: Textile chemistry Textile chemicals Cellulose -- Chemistry
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10948/12175 , vital:27041
- Description: This study is aimed at extracting cellulose and nanocelluloses (cellulose nanocrystals (CNCs) and cellulose nanofibres (CNFs)) from maize stalks and flax fibres. Both flax fibres and maize stalks are composed of cellulose, lignin, hemicellulose and extractives. The extraction of cellulose involves the removal of lignin, hemicellulose and extractives. The presence of these components in plant fibres hinders the extraction of cellulose and nanocelluloses. Prior to extraction of cellulose, the different concentrations (1 wt.%, 1.5 wt.% and 2 wt.%) of NaOH were optimised. However, chemical compositions and XRD results revealed that the treatment of flax fibres with 1.5 wt.% sodium hydroxide (NaOH) gives optimum results and this concentration was further selected for the extraction of cellulose. Cellulose was extracted by chemical treatments (sodium hydroxide (NaOH), sodium chlorite (NaClO2) and potassium hydroxide (KOH)) and a combination of chemical treatments and mechanical process (supermass colloider). The materials obtained after each treatment stage during the extraction process were characterised by different characterisation techniques such as Fourier transform infrared (FTIR) spectroscopy, environmental scanning electron microscopy (ESEM), X-ray diffraction (XRD) and thermogravimetric analysis (TGA). The results from the aforementioned characterisation techniques confirmed that cellulose was successfully extracted from flax fibres and maize stalks. Cellulose nanocrystals (CNCs) were extracted by sulphuric acid hydrolysis accompanied with ultra-sonication from cellulose obtained from flax fibres and maize stalks. The extracted CNCs were rod-like material with diameters and lengths in nanoscale and microscale, respectively. On the other hand, cellulose nanofibres (CNFs) were extracted by mechanical process (supermass colloider). The extracted CNFs were web-like material with diameters and lengths in nanoscale and microscale, respectively. The dimensions of nanocelluloses were measured by atomic force microscopy (AFM). Their dispersion was investigated by light polarised microscopy. The extracted nanocelluloses and cellulose were used to produce nanopapers and micropaper. Nanopapers mimic the traditional paper, the only difference of the nanopapers is that they are produced from high aspect ratio nanomaterials. Both nanopapers and micropapers were prepared by solvent evaporating method. Their thermal, optical and mechanical properties were investigated and compared. The mechanical and thermal properties of nanopapers produced from CNFs were better than those produced from CNCs and micropapers. On the other hand, nanopapers produced from CNCs were more transparent in comparison to nanopapers produced from CNFs and micropapers. Cellulosic fibres have attracted a considerable attention in composite materials due to their high tensile strength and tensile modulus. This study is focused on the development of biocomposites of polyfurfuryl alcohol (PFA) by in-situ polymerisation in the presence of acid catalyst (p-toluene sulphonic acid). Biocomposites were produced by reinforcing PFA with flax fibres (untreated and treated), nanoparticles and CNCs. The biocomposites reinforced with CNCs and flax fibres showed an improvement in mechanical, thermal and thermo-mechanical properties. On the other hand, biocomposites reinforced with nanoparticles obtained from treated maize stalks showed an improvement in mechanical and thermal properties while biocomposites reinforced with nanoparticles obtained from untreated maize stalks showed lower mechanical properties and decreased thermal stability.
- Full Text:
- Date Issued: 2016
- Authors: Mtibe, Asanda , Linganiso, Linda
- Date: 2016
- Subjects: Textile chemistry Textile chemicals Cellulose -- Chemistry
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10948/12175 , vital:27041
- Description: This study is aimed at extracting cellulose and nanocelluloses (cellulose nanocrystals (CNCs) and cellulose nanofibres (CNFs)) from maize stalks and flax fibres. Both flax fibres and maize stalks are composed of cellulose, lignin, hemicellulose and extractives. The extraction of cellulose involves the removal of lignin, hemicellulose and extractives. The presence of these components in plant fibres hinders the extraction of cellulose and nanocelluloses. Prior to extraction of cellulose, the different concentrations (1 wt.%, 1.5 wt.% and 2 wt.%) of NaOH were optimised. However, chemical compositions and XRD results revealed that the treatment of flax fibres with 1.5 wt.% sodium hydroxide (NaOH) gives optimum results and this concentration was further selected for the extraction of cellulose. Cellulose was extracted by chemical treatments (sodium hydroxide (NaOH), sodium chlorite (NaClO2) and potassium hydroxide (KOH)) and a combination of chemical treatments and mechanical process (supermass colloider). The materials obtained after each treatment stage during the extraction process were characterised by different characterisation techniques such as Fourier transform infrared (FTIR) spectroscopy, environmental scanning electron microscopy (ESEM), X-ray diffraction (XRD) and thermogravimetric analysis (TGA). The results from the aforementioned characterisation techniques confirmed that cellulose was successfully extracted from flax fibres and maize stalks. Cellulose nanocrystals (CNCs) were extracted by sulphuric acid hydrolysis accompanied with ultra-sonication from cellulose obtained from flax fibres and maize stalks. The extracted CNCs were rod-like material with diameters and lengths in nanoscale and microscale, respectively. On the other hand, cellulose nanofibres (CNFs) were extracted by mechanical process (supermass colloider). The extracted CNFs were web-like material with diameters and lengths in nanoscale and microscale, respectively. The dimensions of nanocelluloses were measured by atomic force microscopy (AFM). Their dispersion was investigated by light polarised microscopy. The extracted nanocelluloses and cellulose were used to produce nanopapers and micropaper. Nanopapers mimic the traditional paper, the only difference of the nanopapers is that they are produced from high aspect ratio nanomaterials. Both nanopapers and micropapers were prepared by solvent evaporating method. Their thermal, optical and mechanical properties were investigated and compared. The mechanical and thermal properties of nanopapers produced from CNFs were better than those produced from CNCs and micropapers. On the other hand, nanopapers produced from CNCs were more transparent in comparison to nanopapers produced from CNFs and micropapers. Cellulosic fibres have attracted a considerable attention in composite materials due to their high tensile strength and tensile modulus. This study is focused on the development of biocomposites of polyfurfuryl alcohol (PFA) by in-situ polymerisation in the presence of acid catalyst (p-toluene sulphonic acid). Biocomposites were produced by reinforcing PFA with flax fibres (untreated and treated), nanoparticles and CNCs. The biocomposites reinforced with CNCs and flax fibres showed an improvement in mechanical, thermal and thermo-mechanical properties. On the other hand, biocomposites reinforced with nanoparticles obtained from treated maize stalks showed an improvement in mechanical and thermal properties while biocomposites reinforced with nanoparticles obtained from untreated maize stalks showed lower mechanical properties and decreased thermal stability.
- Full Text:
- Date Issued: 2016
Biofuels and rural development: A case study of the Mapfura-Makhura Incubator and small-scale farmers in the Limpopo Province
- Authors: Mothupi, Frans Makwena
- Date: 2016
- Language: English
- Type: Thesis , Masters , MSocSc
- Identifier: http://hdl.handle.net/10962/1488 , vital:20062
- Description: The primary objective of the study is to examine the livelihood impact of biofuel production on small-scale rural farmers participating in the MMI project in the local districts in Limpopo province. The study is theoretically underpinned by the sustainable livelihoods framework which provides a nuanced analysis of the complex nature of poverty and livelihoods. The framework was used to examine how MMI as a structure with its own processes (incubator model) plays a role in creating a means for farmers to have more access to livelihood assets which would help them achieve improved livelihoods outcome. The findings of this study reflect what has already been articulated in literature about small-scale biofuel projects. This study shows that MMI’s incubator plays an important role for 73% of the farmers to access all of the livelihood assets and ultimately improving their farm income and food security. Furthermore, 90% of the participants admitted to have received support from MMI in a number of ways. This includes the provision of farming inputs, labour and access to markets in addition to training, mentoring and coaching. The study also found that despite the overwhelming support, both MMI and farmers face a number of challenges. Farmers still lack adequate farming inputs, transport, access to markets and vulnerability to natural disasters. MMI faces challenges in raising funds to provide inputs to all their incubatees and lack of adequate mechanization. Lack of transportation affects both farmers and MMI in that farmers find it difficult to access MMI service. In the same light, MMI has found it difficult to reach farmers for post-incubation, coaching and mentoring or delivering inputs; this can be challenging and a costly process. MMI’s biofuel production project has the capability for improving rural livelihoods through agriculture. The study concludes by recommending that MMI should improve its own capacity in order for them to better the lives of the farmers they assist. This study is significant for contributing to a field which has received less academic and research attention in South Africa. Its scholarly contribution will enhance the existing body of knowledge on biofuels and rural development in South Africa
- Full Text:
- Date Issued: 2016
- Authors: Mothupi, Frans Makwena
- Date: 2016
- Language: English
- Type: Thesis , Masters , MSocSc
- Identifier: http://hdl.handle.net/10962/1488 , vital:20062
- Description: The primary objective of the study is to examine the livelihood impact of biofuel production on small-scale rural farmers participating in the MMI project in the local districts in Limpopo province. The study is theoretically underpinned by the sustainable livelihoods framework which provides a nuanced analysis of the complex nature of poverty and livelihoods. The framework was used to examine how MMI as a structure with its own processes (incubator model) plays a role in creating a means for farmers to have more access to livelihood assets which would help them achieve improved livelihoods outcome. The findings of this study reflect what has already been articulated in literature about small-scale biofuel projects. This study shows that MMI’s incubator plays an important role for 73% of the farmers to access all of the livelihood assets and ultimately improving their farm income and food security. Furthermore, 90% of the participants admitted to have received support from MMI in a number of ways. This includes the provision of farming inputs, labour and access to markets in addition to training, mentoring and coaching. The study also found that despite the overwhelming support, both MMI and farmers face a number of challenges. Farmers still lack adequate farming inputs, transport, access to markets and vulnerability to natural disasters. MMI faces challenges in raising funds to provide inputs to all their incubatees and lack of adequate mechanization. Lack of transportation affects both farmers and MMI in that farmers find it difficult to access MMI service. In the same light, MMI has found it difficult to reach farmers for post-incubation, coaching and mentoring or delivering inputs; this can be challenging and a costly process. MMI’s biofuel production project has the capability for improving rural livelihoods through agriculture. The study concludes by recommending that MMI should improve its own capacity in order for them to better the lives of the farmers they assist. This study is significant for contributing to a field which has received less academic and research attention in South Africa. Its scholarly contribution will enhance the existing body of knowledge on biofuels and rural development in South Africa
- Full Text:
- Date Issued: 2016