Food security in a perfect storm: using the ecosystem services framework to increase understanding
- Poppy, G M, Chiotha, S, Eigenbrod, Felix, Harvey, C A, Honzák, M, Hudson, M D, Jarvis, A, Madise, N J, Schreckenberg, Kate, Shackleton, Charlie M, Villa, F, Dawson, T P
- Authors: Poppy, G M , Chiotha, S , Eigenbrod, Felix , Harvey, C A , Honzák, M , Hudson, M D , Jarvis, A , Madise, N J , Schreckenberg, Kate , Shackleton, Charlie M , Villa, F , Dawson, T P
- Date: 2014
- Language: English
- Type: article , text
- Identifier: http://hdl.handle.net/10962/60952 , vital:27900 , http://dx.doi.org/10.1098/rstb.2012.0288
- Description: Achieving food security in a ‘perfect storm’ scenario is a grand challenge for society. Climate change and an expanding global population act in concert to make global food security even more complex and demanding. As achieving food security and the millennium development goal (MDG) to eradicate hunger influences the attainment of other MDGs, it is imperative that we offer solutions which are complementary and do not oppose one another. Sustainable intensification of agriculture has been proposed as a way to address hunger while also minimizing further environmental impact. However, the desire to raise productivity and yields has historically led to a degraded environment, reduced biodiversity and a reduction in ecosystem services (ES), with the greatest impacts affecting the poor. This paper proposes that the ES framework coupled with a policy response framework, for example Driver-Pressure-State-Impact-Response (DPSIR), can allow food security to be delivered alongside healthy ecosystems, which provide many other valuable services to humankind. Too often, agro-ecosystems have been considered as separate from other natural ecosystems and insufficient attention has been paid to the way in which services can flow to and from the agro-ecosystem to surrounding ecosystems. Highlighting recent research in a large multi-disciplinary project (ASSETS), we illustrate the ES approach to food security using a case study from the Zomba district of Malawi.
- Full Text:
- Date Issued: 2014
- Authors: Poppy, G M , Chiotha, S , Eigenbrod, Felix , Harvey, C A , Honzák, M , Hudson, M D , Jarvis, A , Madise, N J , Schreckenberg, Kate , Shackleton, Charlie M , Villa, F , Dawson, T P
- Date: 2014
- Language: English
- Type: article , text
- Identifier: http://hdl.handle.net/10962/60952 , vital:27900 , http://dx.doi.org/10.1098/rstb.2012.0288
- Description: Achieving food security in a ‘perfect storm’ scenario is a grand challenge for society. Climate change and an expanding global population act in concert to make global food security even more complex and demanding. As achieving food security and the millennium development goal (MDG) to eradicate hunger influences the attainment of other MDGs, it is imperative that we offer solutions which are complementary and do not oppose one another. Sustainable intensification of agriculture has been proposed as a way to address hunger while also minimizing further environmental impact. However, the desire to raise productivity and yields has historically led to a degraded environment, reduced biodiversity and a reduction in ecosystem services (ES), with the greatest impacts affecting the poor. This paper proposes that the ES framework coupled with a policy response framework, for example Driver-Pressure-State-Impact-Response (DPSIR), can allow food security to be delivered alongside healthy ecosystems, which provide many other valuable services to humankind. Too often, agro-ecosystems have been considered as separate from other natural ecosystems and insufficient attention has been paid to the way in which services can flow to and from the agro-ecosystem to surrounding ecosystems. Highlighting recent research in a large multi-disciplinary project (ASSETS), we illustrate the ES approach to food security using a case study from the Zomba district of Malawi.
- Full Text:
- Date Issued: 2014
Fish utilization of surf-zones. Are they changing? A case study of the sheltered, warm-temperate King’s Beach
- Rishworth, Gavin M, Strydom, Nadine A, Potts, Warren M
- Authors: Rishworth, Gavin M , Strydom, Nadine A , Potts, Warren M
- Date: 2015
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/124504 , vital:35619 , https://doi.org/10.1080/15627020.2014.11407616
- Description: Surf-zone fish communities and their shifts over time are generally poorly understood. The aim of this study was to compare the current surf-zone fish assemblage at King’s Beach, South Africa, to a similar study conducted three decades ago, before the collapse of many exploited shore fishes in the region. Beach seine nets (mesh sizes of 10 and 50 mm) were used to target juvenile and adult fishes bimonthly from February to August 2011 over the high tide around sunset. A total of 14 species were recorded in both the 30mand 100mseine nets. The catch in these seine nets was dominated by Pomadasys olivaceus and Liza richardsonii, and this was significantly different to three decades ago, when P. olivaceus, Sarpa salpa and Diplodus capensis dominated the catch. Important linefish species belonging to the Sparidae and Sciaenidae families were significantly smaller and less abundant in this study. Two sparids, S. salpa and Lithognathus mormyrus, which made a large contribution to the surf-zone catch three decades ago were absent during this study. Reasons for the significant shifts in the surf-zone fish community, including overexploitation of the linefish and potential habitat modification, are discussed.
- Full Text:
- Date Issued: 2015
- Authors: Rishworth, Gavin M , Strydom, Nadine A , Potts, Warren M
- Date: 2015
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/124504 , vital:35619 , https://doi.org/10.1080/15627020.2014.11407616
- Description: Surf-zone fish communities and their shifts over time are generally poorly understood. The aim of this study was to compare the current surf-zone fish assemblage at King’s Beach, South Africa, to a similar study conducted three decades ago, before the collapse of many exploited shore fishes in the region. Beach seine nets (mesh sizes of 10 and 50 mm) were used to target juvenile and adult fishes bimonthly from February to August 2011 over the high tide around sunset. A total of 14 species were recorded in both the 30mand 100mseine nets. The catch in these seine nets was dominated by Pomadasys olivaceus and Liza richardsonii, and this was significantly different to three decades ago, when P. olivaceus, Sarpa salpa and Diplodus capensis dominated the catch. Important linefish species belonging to the Sparidae and Sciaenidae families were significantly smaller and less abundant in this study. Two sparids, S. salpa and Lithognathus mormyrus, which made a large contribution to the surf-zone catch three decades ago were absent during this study. Reasons for the significant shifts in the surf-zone fish community, including overexploitation of the linefish and potential habitat modification, are discussed.
- Full Text:
- Date Issued: 2015
Fatty acid profiles reveal temporal and spatial differentiation in diets within and among syntopic rocky shore suspension-feeders:
- Richoux, Nicole B, Vermeulen, Ilke, Froneman, P William
- Authors: Richoux, Nicole B , Vermeulen, Ilke , Froneman, P William
- Date: 2014
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/143346 , vital:38238 , doi: 10.3354/meps10581
- Description: Regional and temporal variations in the diets of rocky shore suspension-feeders (the volcano barnacle Tetraclita serrata, the brown mussel Perna perna and the reef-building polychaete Gunnarea gaimardi) were assessed using fatty acid profiling. Specimens were collected up-current and down-current of a river mouth in 2 coastal regions ~50 km apart along southeastern South Africa during March and July of 2009. One of the rivers represents a marine-dominated system, and the other a freshwater-dominated system. Our aims were to assess any dietary differences among the 3 suspension-feeders, spatial changes in diet within each species (at regional and local scales—50 and 15 km, respectively), and temporal changes in diet within each species.
- Full Text:
- Date Issued: 2014
- Authors: Richoux, Nicole B , Vermeulen, Ilke , Froneman, P William
- Date: 2014
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/143346 , vital:38238 , doi: 10.3354/meps10581
- Description: Regional and temporal variations in the diets of rocky shore suspension-feeders (the volcano barnacle Tetraclita serrata, the brown mussel Perna perna and the reef-building polychaete Gunnarea gaimardi) were assessed using fatty acid profiling. Specimens were collected up-current and down-current of a river mouth in 2 coastal regions ~50 km apart along southeastern South Africa during March and July of 2009. One of the rivers represents a marine-dominated system, and the other a freshwater-dominated system. Our aims were to assess any dietary differences among the 3 suspension-feeders, spatial changes in diet within each species (at regional and local scales—50 and 15 km, respectively), and temporal changes in diet within each species.
- Full Text:
- Date Issued: 2014
Fatty acid profiles reveal temporal and spatial differentiation in diets within and among syntopic rocky shore suspension-feeders
- Vermeulen, I, Richoux, N.B, Froneman, Pierre William
- Authors: Vermeulen, I , Richoux, N.B , Froneman, Pierre William
- Date: 2014
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/124269 , vital:35582 , http://dx.doi.10.3354/meps10581
- Description: Regional and temporal variations in the diets of rocky shore suspension-feeders (the volcano barnacle Tetraclita serrata, the brown mussel Perna perna and the reef-building poly- chaete Gunnarea gaimardi) were assessed using fatty acid profiling. Specimens were collected up-current and down-current of a river mouth in 2 coastal regions ~50 km apart along southeast- ern South Africa during March and July of 2009. One of the rivers represents a marine-dominated system, and the other a freshwater-dominated system. Our aims were to assess any dietary differences among the 3 suspension-feeders, spatial changes in diet within each species (at regional and local scales—50 and 15 km, respectively), and temporal changes in diet within each species. Fatty acid profiles clearly distinguished the species, with barnacles characterised by dinoflagellate and zooplankton-associated fatty acids; polychaetes, by diatom-associated fatty acids; and mussels, by a combination of mixed phytoplankton and mollusc-specific fatty acids (non-methylene interrupted). These interspecific differences probably arose in part from the contrasting feeding mechanisms employed. The distinctions in diet contribute to ecological partitioning of the sus- pended food within a highly competitive habitat. Regional- and local-scale intraspecific differences in diets were minimal to absent, but temporal distinctions in intraspecific diets were dominant features in the data set, confirming that the trophic environment for suspension-feeders can change markedly throughout a year.
- Full Text: false
- Date Issued: 2014
- Authors: Vermeulen, I , Richoux, N.B , Froneman, Pierre William
- Date: 2014
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/124269 , vital:35582 , http://dx.doi.10.3354/meps10581
- Description: Regional and temporal variations in the diets of rocky shore suspension-feeders (the volcano barnacle Tetraclita serrata, the brown mussel Perna perna and the reef-building poly- chaete Gunnarea gaimardi) were assessed using fatty acid profiling. Specimens were collected up-current and down-current of a river mouth in 2 coastal regions ~50 km apart along southeast- ern South Africa during March and July of 2009. One of the rivers represents a marine-dominated system, and the other a freshwater-dominated system. Our aims were to assess any dietary differences among the 3 suspension-feeders, spatial changes in diet within each species (at regional and local scales—50 and 15 km, respectively), and temporal changes in diet within each species. Fatty acid profiles clearly distinguished the species, with barnacles characterised by dinoflagellate and zooplankton-associated fatty acids; polychaetes, by diatom-associated fatty acids; and mussels, by a combination of mixed phytoplankton and mollusc-specific fatty acids (non-methylene interrupted). These interspecific differences probably arose in part from the contrasting feeding mechanisms employed. The distinctions in diet contribute to ecological partitioning of the sus- pended food within a highly competitive habitat. Regional- and local-scale intraspecific differences in diets were minimal to absent, but temporal distinctions in intraspecific diets were dominant features in the data set, confirming that the trophic environment for suspension-feeders can change markedly throughout a year.
- Full Text: false
- Date Issued: 2014
Family functioning and life satisfaction and happiness in South African households
- Botha, Ferdi, Booysen, Frikkie
- Authors: Botha, Ferdi , Booysen, Frikkie
- Date: 2014
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/396048 , vital:69146 , xlink:href="https://doi.org/10.1007/s11205-013-0485-6"
- Description: Families form an integral part of society and in fostering individual well-being. Despite the acknowledged importance of family, the association between family functioning and individual well-being outcomes have remained unexplored in the current body of knowledge. This paper explores the association between family functioning and reported levels of life satisfaction and happiness in South Africa. The paper employs the Family Attachment and Changeability Index (FACI8) to measure family functioning, using data from the 2011 South African Social Attitudes Survey. Four measures of family functioning are utilised, namely the aggregate FACI8 scale, the attachment and changeability sub-scales, and family functioning type. Improvements in the level of family functioning as well as in the levels of attachment and changeability are positively associated with life satisfaction and happiness. In addition, individuals living in midrange or balanced family functioning types are more satisfied with life and happier compared to persons living in extremely or moderately dysfunctional families. The findings highlight the importance of supportive intra-family dynamics in fostering greater individual well-being. This in turn places emphasis on the investigation of likely correlates of family functioning and impact evaluations of family-focused social work interventions’ impact on family functioning as areas for future research.
- Full Text:
- Date Issued: 2014
- Authors: Botha, Ferdi , Booysen, Frikkie
- Date: 2014
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/396048 , vital:69146 , xlink:href="https://doi.org/10.1007/s11205-013-0485-6"
- Description: Families form an integral part of society and in fostering individual well-being. Despite the acknowledged importance of family, the association between family functioning and individual well-being outcomes have remained unexplored in the current body of knowledge. This paper explores the association between family functioning and reported levels of life satisfaction and happiness in South Africa. The paper employs the Family Attachment and Changeability Index (FACI8) to measure family functioning, using data from the 2011 South African Social Attitudes Survey. Four measures of family functioning are utilised, namely the aggregate FACI8 scale, the attachment and changeability sub-scales, and family functioning type. Improvements in the level of family functioning as well as in the levels of attachment and changeability are positively associated with life satisfaction and happiness. In addition, individuals living in midrange or balanced family functioning types are more satisfied with life and happier compared to persons living in extremely or moderately dysfunctional families. The findings highlight the importance of supportive intra-family dynamics in fostering greater individual well-being. This in turn places emphasis on the investigation of likely correlates of family functioning and impact evaluations of family-focused social work interventions’ impact on family functioning as areas for future research.
- Full Text:
- Date Issued: 2014
Factors leading to the high failure rate of grade 12 learners in the Ngqeleni area: A case study of two schools in the Ngqeleni area of the Libode mega district, Eastern Cape.
- Authors: Maqokolo, Gideon Zitobile
- Date: 2014
- Language: English
- Type: Masters theses , text
- Identifier: http://hdl.handle.net/11260/3444 , vital:43390
- Description: The study investigated the factors that lead to the high failure rate of grade 12 learners of the two high schools in the Ngqeleni area of Libode Mega District of the Eastern Cape, South Africa. The study was qualitative in nature; therefore interviews were used as the method of collecting data. Seven SMT members, four parents and four learners were, randomly selected from the two schools in the Ngqeleni area of Libode Mega District. The researcher randomly selected the participants then interviewed them. The researcher used a video recoder as an instrument to record the responses from the participants. To analyse data, the researcher transcribed the interview responses and interpreted them. The main findings of the study showed that the high failure rate was caused by the following factors: over-croweded classes, shortage of teaching and learnin~ materials, lack of parental involvement, teachers' low morale, poor learner discipline, teachers experiencing problems in implementing government policies, work-load and as such teaching becoming stressful. The researcher in his study therefore recommends that the Department of Education plans more workshops for schools to capacitate them. There should be provision for more classrooms and incentives for teachers. , Thesis (MMED) -- Faculty of Educational Sciences, 2019
- Full Text:
- Date Issued: 2014
- Authors: Maqokolo, Gideon Zitobile
- Date: 2014
- Language: English
- Type: Masters theses , text
- Identifier: http://hdl.handle.net/11260/3444 , vital:43390
- Description: The study investigated the factors that lead to the high failure rate of grade 12 learners of the two high schools in the Ngqeleni area of Libode Mega District of the Eastern Cape, South Africa. The study was qualitative in nature; therefore interviews were used as the method of collecting data. Seven SMT members, four parents and four learners were, randomly selected from the two schools in the Ngqeleni area of Libode Mega District. The researcher randomly selected the participants then interviewed them. The researcher used a video recoder as an instrument to record the responses from the participants. To analyse data, the researcher transcribed the interview responses and interpreted them. The main findings of the study showed that the high failure rate was caused by the following factors: over-croweded classes, shortage of teaching and learnin~ materials, lack of parental involvement, teachers' low morale, poor learner discipline, teachers experiencing problems in implementing government policies, work-load and as such teaching becoming stressful. The researcher in his study therefore recommends that the Department of Education plans more workshops for schools to capacitate them. There should be provision for more classrooms and incentives for teachers. , Thesis (MMED) -- Faculty of Educational Sciences, 2019
- Full Text:
- Date Issued: 2014
Fabrication of phthalocyanine-magnetic nanoparticles hybrid nanofibers for degradation of Orange-G
- Modisha, Phillimon, Nyokong, Tebello
- Authors: Modisha, Phillimon , Nyokong, Tebello
- Date: 2014
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/190394 , vital:44990 , xlink:href="https://doi.org/10.1016/j.molcata.2013.10.012"
- Description: Conjugates of zinc octacarboxy phthalocyanine (ZnOCPc) with magnetic nanoparticles (MNPs) were electrospun into fibers using polyamide-6 (PA-6) polymer. The ZnOCPc or ZnOCPc-MNPs conjugates on the fiber were employed for the photodegradation of an azo dye (Orange-G). The functionality of the ZnOCPc and ZnOCPc-MNPs was maintained within a solid fiber core. The singlet oxygen generation increases as we increase the fiber diameter by increasing the ZnOCPc concentration. The singlet oxygen quantum yield was higher for PA-6/ZnOCPc-MNPs nanofibers compared to PA-6/ZnOCPc. The rate of degradation of Orange-G increased with an increase in singlet oxygen quantum yield. Moreover, the kinetic analysis of the photodecomposition of Orange-G showed that its disappearance followed the Langmuir–Hinshelwood model.
- Full Text:
- Date Issued: 2014
- Authors: Modisha, Phillimon , Nyokong, Tebello
- Date: 2014
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/190394 , vital:44990 , xlink:href="https://doi.org/10.1016/j.molcata.2013.10.012"
- Description: Conjugates of zinc octacarboxy phthalocyanine (ZnOCPc) with magnetic nanoparticles (MNPs) were electrospun into fibers using polyamide-6 (PA-6) polymer. The ZnOCPc or ZnOCPc-MNPs conjugates on the fiber were employed for the photodegradation of an azo dye (Orange-G). The functionality of the ZnOCPc and ZnOCPc-MNPs was maintained within a solid fiber core. The singlet oxygen generation increases as we increase the fiber diameter by increasing the ZnOCPc concentration. The singlet oxygen quantum yield was higher for PA-6/ZnOCPc-MNPs nanofibers compared to PA-6/ZnOCPc. The rate of degradation of Orange-G increased with an increase in singlet oxygen quantum yield. Moreover, the kinetic analysis of the photodecomposition of Orange-G showed that its disappearance followed the Langmuir–Hinshelwood model.
- Full Text:
- Date Issued: 2014
Expurgating the Monstrous: an analysis of the South African Daily Sun's coverage of gang rape
- Boshoff, Priscilla A, Prinsloo, Jeanne
- Authors: Boshoff, Priscilla A , Prinsloo, Jeanne
- Date: 2014
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/143436 , vital:38246 , DOI: 10.1080/14680777.2014.903286
- Description: The most widely read South African tabloid, the Daily Sun, covered the “Soweto gang rape” in 2012. These acts were recorded by the perpetrators on mobile phones and “went viral” as the media continuously noted. We draw on the concept of provider love that informs relations of intimacy in certain South African spaces, central to which is its materiality and the assumption that a “real” man is able to command material resources, a prerequisite for having both a girlfriend and sex. For working class and township youth these possibilities are constrained and their sense of being left behind is lived in gendered ways with violent masculinities becoming a marker of tough sexual masculinity. Informed by Foucauldian understandings of discourse, the paper undertakes a close reading of this coverage, including the reporting, editorials, and letters. If those arrested for rape are constituted as monstrous, the analysis indicates how the responses are similarly vengeful. These responses deny the forms of masculinity produced within these marginalised spaces and foreclose on other possibilities for understanding these violent acts.
- Full Text:
- Date Issued: 2014
- Authors: Boshoff, Priscilla A , Prinsloo, Jeanne
- Date: 2014
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/143436 , vital:38246 , DOI: 10.1080/14680777.2014.903286
- Description: The most widely read South African tabloid, the Daily Sun, covered the “Soweto gang rape” in 2012. These acts were recorded by the perpetrators on mobile phones and “went viral” as the media continuously noted. We draw on the concept of provider love that informs relations of intimacy in certain South African spaces, central to which is its materiality and the assumption that a “real” man is able to command material resources, a prerequisite for having both a girlfriend and sex. For working class and township youth these possibilities are constrained and their sense of being left behind is lived in gendered ways with violent masculinities becoming a marker of tough sexual masculinity. Informed by Foucauldian understandings of discourse, the paper undertakes a close reading of this coverage, including the reporting, editorials, and letters. If those arrested for rape are constituted as monstrous, the analysis indicates how the responses are similarly vengeful. These responses deny the forms of masculinity produced within these marginalised spaces and foreclose on other possibilities for understanding these violent acts.
- Full Text:
- Date Issued: 2014
Exploring Teacher Assessment Practices in The General Education and Training Level in Junior Secondary Schools in Mthatha Education District
- Authors: Xolile, Stwebile
- Date: 2014
- Language: English
- Type: Masters theses , text
- Identifier: http://hdl.handle.net/11260/2933 , vital:43116
- Description: This dissertation is a report of the study that was conducted in rural and urban periphery schools of Mthatha City within Mthatha Education District in the Eastern Cape, a province of South Africa. The study explored teacher-assessment practices in two selected junior secondary schools. The utmost purpose was to determine the nature of teacher-assessment practices in these junior secondary schools. This study involved mainly a quantitative research design and later supplemented by qualitative research design. The target population was made up of 63 teachers from both schools. Sampling entailed simple random sampling for quantitative approach and purposeful sampling for qualitative. Instrumentation involved questionnaires and focus group interviews to gather data for these two different research paradigms used. The data was analysed by means of SPSS for quantitative and thematically for qualitative. The results of this study from both instruments were crystallized, and indicated that teachers were grappling with difficulty in strategies and procedures of assessment due to an ever changing curriculum and overload of work. The main findings were: assessment based on content knowledge of learners, negative impact of teacher re-deployment on assessment, stress accumulated by various challenges such as overload of work and frequent curriculum changes as well as lack of data organisation and gathering. The recommendations were: workshops and training programmes on assessment to be provided to teachers; teachers should use various information sources for conducting assessment; more teachers need to be recruited for understaffing and overloading problems as well as pragmatic assessment strategies should be used for learners assessment. Teachers should be included in matters of curriculum changes and be exposed to in-service training. , Thesis (MMED) -- Faculty of Educational Sciences, 2014
- Full Text:
- Date Issued: 2014
- Authors: Xolile, Stwebile
- Date: 2014
- Language: English
- Type: Masters theses , text
- Identifier: http://hdl.handle.net/11260/2933 , vital:43116
- Description: This dissertation is a report of the study that was conducted in rural and urban periphery schools of Mthatha City within Mthatha Education District in the Eastern Cape, a province of South Africa. The study explored teacher-assessment practices in two selected junior secondary schools. The utmost purpose was to determine the nature of teacher-assessment practices in these junior secondary schools. This study involved mainly a quantitative research design and later supplemented by qualitative research design. The target population was made up of 63 teachers from both schools. Sampling entailed simple random sampling for quantitative approach and purposeful sampling for qualitative. Instrumentation involved questionnaires and focus group interviews to gather data for these two different research paradigms used. The data was analysed by means of SPSS for quantitative and thematically for qualitative. The results of this study from both instruments were crystallized, and indicated that teachers were grappling with difficulty in strategies and procedures of assessment due to an ever changing curriculum and overload of work. The main findings were: assessment based on content knowledge of learners, negative impact of teacher re-deployment on assessment, stress accumulated by various challenges such as overload of work and frequent curriculum changes as well as lack of data organisation and gathering. The recommendations were: workshops and training programmes on assessment to be provided to teachers; teachers should use various information sources for conducting assessment; more teachers need to be recruited for understaffing and overloading problems as well as pragmatic assessment strategies should be used for learners assessment. Teachers should be included in matters of curriculum changes and be exposed to in-service training. , Thesis (MMED) -- Faculty of Educational Sciences, 2014
- Full Text:
- Date Issued: 2014
Exploring a knowledge-focused trajectory for researching environmental learning in the South African curriculum
- Authors: Schudel, Ingrid J
- Date: 2014
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/294375 , vital:57216 , xlink:href="https://www.researchgate.net/publication/305730521"
- Description: This paper explores the past twenty years of environmental learning in the South African curriculum in order to consider how one might best research a knowledge focus within the Fundisa for Change national teacher education programme. In exploring this knowledge focus, the paper draws on international literature. It also extensively, but not exclusively, draws on two key publications which informed the 2002 and the 2011 curriculum changes in South Africa. The paper draws on social realist curriculum theory, underpinned by critical realism. This theoretical perspective, which includes Bernstein’s pedagogic device and particularly recontextualisation of knowledge across the pedagogical landscape, provides a language of description for critically reviewing knowledge and environmental learning. In particular, the review develops five perspectives on environmental knowledge as it pertains to curriculum which include: Perspective #1) new environmental knowledge in the curriculum; Perspective #2) environmental knowledge in local and global contexts; Perspective # 3) dynamic knowledge for open-ended and futuristic thinking; Perspective #4) depth and complexity of environmental knowledge; and Perspective #5) combining discipline-specific core knowledge and skills with a systems perspective. The paper argues for a re-emphasis and review of new environmental knowledge and learning support materials. It suggests a consideration of context-rich but not context-bound explorations of local and global environmental issues and the need for adopting open-ended and futuristic thinking in the context of the dynamism of environmental knowledge. This involves exploring systems of meaning and structures of knowledge in dealing with the complexity of environmental knowledge and acknowledging the challenges of a transformative ideology within such a complex knowledge system. Additionally, the paper argues for creative ways of working across disciplines to develop better understanding of discipline-specific concepts and their potential to contribute to meaningful learning. The paper concludes by suggesting a research trajectory for future environmental education research in the context of the new South African Curriculum and Assessment Policy Statement (CAPS) extending the emphasis in this paper on the official recontextualising field, to fields across the entire pedagogic device.
- Full Text:
- Date Issued: 2014
- Authors: Schudel, Ingrid J
- Date: 2014
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/294375 , vital:57216 , xlink:href="https://www.researchgate.net/publication/305730521"
- Description: This paper explores the past twenty years of environmental learning in the South African curriculum in order to consider how one might best research a knowledge focus within the Fundisa for Change national teacher education programme. In exploring this knowledge focus, the paper draws on international literature. It also extensively, but not exclusively, draws on two key publications which informed the 2002 and the 2011 curriculum changes in South Africa. The paper draws on social realist curriculum theory, underpinned by critical realism. This theoretical perspective, which includes Bernstein’s pedagogic device and particularly recontextualisation of knowledge across the pedagogical landscape, provides a language of description for critically reviewing knowledge and environmental learning. In particular, the review develops five perspectives on environmental knowledge as it pertains to curriculum which include: Perspective #1) new environmental knowledge in the curriculum; Perspective #2) environmental knowledge in local and global contexts; Perspective # 3) dynamic knowledge for open-ended and futuristic thinking; Perspective #4) depth and complexity of environmental knowledge; and Perspective #5) combining discipline-specific core knowledge and skills with a systems perspective. The paper argues for a re-emphasis and review of new environmental knowledge and learning support materials. It suggests a consideration of context-rich but not context-bound explorations of local and global environmental issues and the need for adopting open-ended and futuristic thinking in the context of the dynamism of environmental knowledge. This involves exploring systems of meaning and structures of knowledge in dealing with the complexity of environmental knowledge and acknowledging the challenges of a transformative ideology within such a complex knowledge system. Additionally, the paper argues for creative ways of working across disciplines to develop better understanding of discipline-specific concepts and their potential to contribute to meaningful learning. The paper concludes by suggesting a research trajectory for future environmental education research in the context of the new South African Curriculum and Assessment Policy Statement (CAPS) extending the emphasis in this paper on the official recontextualising field, to fields across the entire pedagogic device.
- Full Text:
- Date Issued: 2014
Enhanced optical limiting performance in phthalocyanine-quantum dot nanocomposites by free-carrier absorption mechanism
- Sanusi, Kayode, Khene, Samson M, Nyokong, Tebello
- Authors: Sanusi, Kayode , Khene, Samson M , Nyokong, Tebello
- Date: 2014
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/193904 , vital:45404 , xlink:href="https://doi.org/10.1016/j.optmat.2014.07.024"
- Description: Enhanced nonlinear optical properties (in dimethyl sulphoxide) is observed for 2(3),9(10),16(17),23(24)-tetrakis-(4-aminophenoxy)phthalocyaninato indium(III) chloride (InPc) when covalently linked to CdSe/ZnS or CdSe quantum dots (QDs). The experimental nonlinear optical parameters were obtained from Z-Scan measurements. Contributions from two-photon absorption (2PA) due to the InPc, and free-carrier absorption (FCA) by QDS have been identified as the main factors responsible for the enhanced optical limiting. The effective nonlinear absorption coefficient for InPc-CdSe/ZnS was found to be 700.0 cm/GW. The FCA cross-sections for InPc-CdSe/ZnS and InPc-CdSe composites were found to be 1.52 × 10−19 and 6.00 × 10−20 cm2 respectively. A much lower limiting threshold of 92 mJ cm−2 was observed for InPc-CdSe/ZnS nanocomposite, hence, making it suitable for use as optical limiting material. Density Functional Theory (DFT) calculations on similar phthalocyanine-quantum dots system was modeled in order to explain the enhancement in the observed nonlinear optical properties of the Pc in the presence of the QDs. The experimentally determined nonlinear optical properties are well within the range of the DFT calculated properties.
- Full Text:
- Date Issued: 2014
- Authors: Sanusi, Kayode , Khene, Samson M , Nyokong, Tebello
- Date: 2014
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/193904 , vital:45404 , xlink:href="https://doi.org/10.1016/j.optmat.2014.07.024"
- Description: Enhanced nonlinear optical properties (in dimethyl sulphoxide) is observed for 2(3),9(10),16(17),23(24)-tetrakis-(4-aminophenoxy)phthalocyaninato indium(III) chloride (InPc) when covalently linked to CdSe/ZnS or CdSe quantum dots (QDs). The experimental nonlinear optical parameters were obtained from Z-Scan measurements. Contributions from two-photon absorption (2PA) due to the InPc, and free-carrier absorption (FCA) by QDS have been identified as the main factors responsible for the enhanced optical limiting. The effective nonlinear absorption coefficient for InPc-CdSe/ZnS was found to be 700.0 cm/GW. The FCA cross-sections for InPc-CdSe/ZnS and InPc-CdSe composites were found to be 1.52 × 10−19 and 6.00 × 10−20 cm2 respectively. A much lower limiting threshold of 92 mJ cm−2 was observed for InPc-CdSe/ZnS nanocomposite, hence, making it suitable for use as optical limiting material. Density Functional Theory (DFT) calculations on similar phthalocyanine-quantum dots system was modeled in order to explain the enhancement in the observed nonlinear optical properties of the Pc in the presence of the QDs. The experimentally determined nonlinear optical properties are well within the range of the DFT calculated properties.
- Full Text:
- Date Issued: 2014
Enhanced Optical Limiting Behavior of an Indium Phthalocyanine–Single-Walled Carbon Nanotube Composite
- Sanusi, Kayode, Amuhaya, Edith K, Nyokong, Tebello
- Authors: Sanusi, Kayode , Amuhaya, Edith K , Nyokong, Tebello
- Date: 2014
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/193871 , vital:45401 , xlink:href="https://doi.org/10.1021/jp501469e "
- Description: The nonlinear optical behavior of 2(3),9(10),16(17),23(24)-tetrakis-(4-aminophenoxy) phthalocyaninato indium (III) chloride (2) and its carbon nanotube composite in dimethylsulfoxide (DMSO) and dimethylformamide (DMF) solutions is described. The nonlinear third-order susceptibility and second-order hyperpolarizability values are also reported. A large nonlinear absorption that increased on covalent linking with single-walled carbon nanotubes (SWCNTs) was observed for the compound in DMSO. The nanosecond nonlinear absorption and the optical limiting behavior of this complex are shown to be dominated by a strong excited state absorption from a two-photon pumped state. The optical limiter using the new nanocomposite material (SWCNT-2) in the appropriate solvent showed a much lower threshold for optical limiting together with a much lower transmission at high fluences than previously reported nanocomposite limiters. The optical properties of the phthalocyanine and its conjugate were found to show high sensitivity toward the change of solvent matrix.
- Full Text:
- Date Issued: 2014
- Authors: Sanusi, Kayode , Amuhaya, Edith K , Nyokong, Tebello
- Date: 2014
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/193871 , vital:45401 , xlink:href="https://doi.org/10.1021/jp501469e "
- Description: The nonlinear optical behavior of 2(3),9(10),16(17),23(24)-tetrakis-(4-aminophenoxy) phthalocyaninato indium (III) chloride (2) and its carbon nanotube composite in dimethylsulfoxide (DMSO) and dimethylformamide (DMF) solutions is described. The nonlinear third-order susceptibility and second-order hyperpolarizability values are also reported. A large nonlinear absorption that increased on covalent linking with single-walled carbon nanotubes (SWCNTs) was observed for the compound in DMSO. The nanosecond nonlinear absorption and the optical limiting behavior of this complex are shown to be dominated by a strong excited state absorption from a two-photon pumped state. The optical limiter using the new nanocomposite material (SWCNT-2) in the appropriate solvent showed a much lower threshold for optical limiting together with a much lower transmission at high fluences than previously reported nanocomposite limiters. The optical properties of the phthalocyanine and its conjugate were found to show high sensitivity toward the change of solvent matrix.
- Full Text:
- Date Issued: 2014
Enhanced nonlinear optical properties of octa-substituted lead and cadmium phthalocyanines when embedded in poly (bisphenol A carbonate) as thin films
- Mkhize, Colin, Britton, Jonathan, Nyokong, Tebello
- Authors: Mkhize, Colin , Britton, Jonathan , Nyokong, Tebello
- Date: 2014
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/241459 , vital:50941 , xlink:href="https://doi.org/10.1016/j.poly.2014.07.025"
- Description: This work presents photophysical and nonlinear optical properties of a novel Cd 2,3-[octakis{4-tert-butylphenoxyphthalocyanine}] (CdOtBPPc) and compare them with those of Pb 2,3-[octakis{4-tert-butylphenoxyphthalocyanine}] (PbOtBPPc). For both the CdOtBPPc and PbOtBPPc, third order imaginary susceptibility and second order hyperpolarizability values were found to be within the limit set for good optical limiters. The Pcs were embedded in poly (methyl methacrylate) (PMMA) and poly(bisphenol A carbonate) (PBC) as thin films. The optical limiting values of the Pcs once embedded in film were found to be greatly improved and the limiting fluence of each film was well below the maximum threshold. Both PbOtBPPc and CdOtBPPc showed better optical limiting when embedded in PBC compared to PMMA. CdOtBPPc shows better nonlinear optical behavior than PbOtBPPc in solution and as thin films, even though the former is aggregated in solution.
- Full Text:
- Date Issued: 2014
- Authors: Mkhize, Colin , Britton, Jonathan , Nyokong, Tebello
- Date: 2014
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/241459 , vital:50941 , xlink:href="https://doi.org/10.1016/j.poly.2014.07.025"
- Description: This work presents photophysical and nonlinear optical properties of a novel Cd 2,3-[octakis{4-tert-butylphenoxyphthalocyanine}] (CdOtBPPc) and compare them with those of Pb 2,3-[octakis{4-tert-butylphenoxyphthalocyanine}] (PbOtBPPc). For both the CdOtBPPc and PbOtBPPc, third order imaginary susceptibility and second order hyperpolarizability values were found to be within the limit set for good optical limiters. The Pcs were embedded in poly (methyl methacrylate) (PMMA) and poly(bisphenol A carbonate) (PBC) as thin films. The optical limiting values of the Pcs once embedded in film were found to be greatly improved and the limiting fluence of each film was well below the maximum threshold. Both PbOtBPPc and CdOtBPPc showed better optical limiting when embedded in PBC compared to PMMA. CdOtBPPc shows better nonlinear optical behavior than PbOtBPPc in solution and as thin films, even though the former is aggregated in solution.
- Full Text:
- Date Issued: 2014
Embracing racial reasoning: the DASO poster controversy and ‘Race’politics in contemporary South Africa
- Vincent, Louise, Howell, Simon
- Authors: Vincent, Louise , Howell, Simon
- Date: 2014
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/141933 , vital:38017 , DOI: 10.1080/03057070.2014.877651
- Description: We examine the response to a poster published by South Africa's official opposition's youth wing, the Democratic Alliance's Student Organisation (DASO) as part of a political campaign in 2012. From commentary that the poster's publication generated, we excavate some of the key discursive strategies used by commentators to negotiate the gulf between the constitutional value of non-racialism and the lived contemporary reality of race in South Africa. Many commentators situated themselves either as ‘colour-blind’, or reformulated ‘race’ as ‘class’ or ‘culture’. In making visible some of these strategies, and the attendant (re-)racialised narratives upon which they rely, we highlight the paradoxes that inhere in the idea of ‘non-racialism’ – a notion that implies that race must simultaneously be thought and ‘un-thought’. Racial categories contrived by apartheid have been somewhat rearranged and rearticulated, but nevertheless continue to operate today as organising principles.
- Full Text:
- Date Issued: 2014
- Authors: Vincent, Louise , Howell, Simon
- Date: 2014
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/141933 , vital:38017 , DOI: 10.1080/03057070.2014.877651
- Description: We examine the response to a poster published by South Africa's official opposition's youth wing, the Democratic Alliance's Student Organisation (DASO) as part of a political campaign in 2012. From commentary that the poster's publication generated, we excavate some of the key discursive strategies used by commentators to negotiate the gulf between the constitutional value of non-racialism and the lived contemporary reality of race in South Africa. Many commentators situated themselves either as ‘colour-blind’, or reformulated ‘race’ as ‘class’ or ‘culture’. In making visible some of these strategies, and the attendant (re-)racialised narratives upon which they rely, we highlight the paradoxes that inhere in the idea of ‘non-racialism’ – a notion that implies that race must simultaneously be thought and ‘un-thought’. Racial categories contrived by apartheid have been somewhat rearranged and rearticulated, but nevertheless continue to operate today as organising principles.
- Full Text:
- Date Issued: 2014
Elephants in Africa: Big, grey biodiversity thieves?
- Kuiper, Timothy R, Parker, Daniel M
- Authors: Kuiper, Timothy R , Parker, Daniel M
- Date: 2014
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/124385 , vital:35601 , https://doi.org/10.2989/16085914.2011.589120
- Description: The conservation of biological diversity is one of the greatest challenges facing humanity today.1,2 Addressing this challenge must inevitably involve the maintenance of the composition, structure and functioning of multi-species ecosystems.2-4 While preventing the loss of particular species is an obvious strategy, a second goal might be to manage for local species diversity and the heterogeneity of habitats.5 A further objective may be the restoration of damaged ecosystems.6 Large herbivore assemblages form an important component of many diverse ecosystems and are of distinct ecological, and hence conservation, value.7-9 On the other hand, herbivores managed at unnaturally high densities may drive detrimental changes in the structural heterogeneity of habitats.10-12 Thus, decision-makers are faced with the challenge of balancing the needs of populations of large herbivores with the preservation of vegetation and ecosystem diversity.9 In light of these considerations, conclusions as to whether large herbivores are ‘good’ or ‘bad’ for biological diversity are both contentious and elusive. Nonetheless, we seek to explore this question with particular reference to African savannah elephants (Loxodonta africana). We discuss whether or not the elephant should be considered a biodiversity thief – a species that upsets the natural diversity of life in the habitat in which it lives.
- Full Text:
- Date Issued: 2014
- Authors: Kuiper, Timothy R , Parker, Daniel M
- Date: 2014
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/124385 , vital:35601 , https://doi.org/10.2989/16085914.2011.589120
- Description: The conservation of biological diversity is one of the greatest challenges facing humanity today.1,2 Addressing this challenge must inevitably involve the maintenance of the composition, structure and functioning of multi-species ecosystems.2-4 While preventing the loss of particular species is an obvious strategy, a second goal might be to manage for local species diversity and the heterogeneity of habitats.5 A further objective may be the restoration of damaged ecosystems.6 Large herbivore assemblages form an important component of many diverse ecosystems and are of distinct ecological, and hence conservation, value.7-9 On the other hand, herbivores managed at unnaturally high densities may drive detrimental changes in the structural heterogeneity of habitats.10-12 Thus, decision-makers are faced with the challenge of balancing the needs of populations of large herbivores with the preservation of vegetation and ecosystem diversity.9 In light of these considerations, conclusions as to whether large herbivores are ‘good’ or ‘bad’ for biological diversity are both contentious and elusive. Nonetheless, we seek to explore this question with particular reference to African savannah elephants (Loxodonta africana). We discuss whether or not the elephant should be considered a biodiversity thief – a species that upsets the natural diversity of life in the habitat in which it lives.
- Full Text:
- Date Issued: 2014
Elephants in Africa: Big, grey biodiversity thieves?
- Kuiper, T R, Parker, Daniel M
- Authors: Kuiper, T R , Parker, Daniel M
- Date: 2014
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/69886 , vital:29591 , http://dx.doi.org/10.1590/ sajs.2014/a0058
- Description: The conservation of biological diversity is one of the greatest challenges facing humanity today.1,2 Addressing this challenge must inevitably involve the maintenance of the composition, structure and functioning of multi-species ecosystems.2-4 While preventing the loss of particular species is an obvious strategy, a second goal might be to manage for local species diversity and the heterogeneity of habitats.5 A further objective may be the restoration of damaged ecosystems.6 Large herbivore assemblages form an important component of many diverse ecosystems and are of distinct ecological, and hence conservation, value.7-9 On the other hand, herbivores managed at unnaturally high densities may drive detrimental changes in the structural heterogeneity of habitats.10-12 Thus, decision-makers are faced with the challenge of balancing the needs of populations of large herbivores with the preservation of vegetation and ecosystem diversity.9 In light of these considerations, conclusions as to whether large herbivores are 'good' or 'bad' for biological diversity are both contentious and elusive. Nonetheless, we seek to explore this question with particular reference to African savannah elephants (Loxodonta africana). We discuss whether or not the elephant should be considered a biodiversity thief - a species that upsets the natural diversity of life in the habitat in which it lives. The African elephant has been driven to local extinction over much of its former range, with hunting for meat and ivory and the conversion of elephant habitat to agriculture constituting the major drivers.5 Given the historical decline in elephant numbers, the conservation of this species appears to be a sensible objective.9,13 However, the protection afforded to elephants in confined (usually fenced) reserves across Africa has distinct implications for the management of local species diversity and the heterogeneity of habitats.14,15 Elephants have been shown to have clear impacts on the structure of vegetation, particularly in woodland habitats12,16,17, and these changes may have knock-on effects for sympatric species10,18,19. The effects of elephants on biological diversity in protected areas are of particular concern in light of how expansion in human populations, and the land-use change that follows, places increasing pressure on reserves to preserve biological diversity.9,10. Change within ecosystems is natural and inevitable and large herbivores have been living in an ever-changing environment for millions of years.20 Changes brought on by elephants, therefore, should not automatically be categorised as undesirable, and short-term changes may be part of an overarching trend of long-term stability.8,21 Furthermore, current elephant impacts can only be adequately assessed in the light of historical (on the scale of centuries) benchmarks, for which accurate information is notoriously scant.10,21 The current impacts of elephant populations on vegetation dynamics in some regions may in fact represent a shift towards a more natural historical state.8,21 Finally, much of the detrimental impacts of elephants on habitat structure and diversity, particularly at smaller scales, has resulted from human interventions (such as the erection of fences and the establishment of artificial water points) that have unnaturally confined elephants to localised areas, disrupted seasonal movements and disturbed the natural dynamics of population processes.5,13,22.
- Full Text:
- Date Issued: 2014
- Authors: Kuiper, T R , Parker, Daniel M
- Date: 2014
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/69886 , vital:29591 , http://dx.doi.org/10.1590/ sajs.2014/a0058
- Description: The conservation of biological diversity is one of the greatest challenges facing humanity today.1,2 Addressing this challenge must inevitably involve the maintenance of the composition, structure and functioning of multi-species ecosystems.2-4 While preventing the loss of particular species is an obvious strategy, a second goal might be to manage for local species diversity and the heterogeneity of habitats.5 A further objective may be the restoration of damaged ecosystems.6 Large herbivore assemblages form an important component of many diverse ecosystems and are of distinct ecological, and hence conservation, value.7-9 On the other hand, herbivores managed at unnaturally high densities may drive detrimental changes in the structural heterogeneity of habitats.10-12 Thus, decision-makers are faced with the challenge of balancing the needs of populations of large herbivores with the preservation of vegetation and ecosystem diversity.9 In light of these considerations, conclusions as to whether large herbivores are 'good' or 'bad' for biological diversity are both contentious and elusive. Nonetheless, we seek to explore this question with particular reference to African savannah elephants (Loxodonta africana). We discuss whether or not the elephant should be considered a biodiversity thief - a species that upsets the natural diversity of life in the habitat in which it lives. The African elephant has been driven to local extinction over much of its former range, with hunting for meat and ivory and the conversion of elephant habitat to agriculture constituting the major drivers.5 Given the historical decline in elephant numbers, the conservation of this species appears to be a sensible objective.9,13 However, the protection afforded to elephants in confined (usually fenced) reserves across Africa has distinct implications for the management of local species diversity and the heterogeneity of habitats.14,15 Elephants have been shown to have clear impacts on the structure of vegetation, particularly in woodland habitats12,16,17, and these changes may have knock-on effects for sympatric species10,18,19. The effects of elephants on biological diversity in protected areas are of particular concern in light of how expansion in human populations, and the land-use change that follows, places increasing pressure on reserves to preserve biological diversity.9,10. Change within ecosystems is natural and inevitable and large herbivores have been living in an ever-changing environment for millions of years.20 Changes brought on by elephants, therefore, should not automatically be categorised as undesirable, and short-term changes may be part of an overarching trend of long-term stability.8,21 Furthermore, current elephant impacts can only be adequately assessed in the light of historical (on the scale of centuries) benchmarks, for which accurate information is notoriously scant.10,21 The current impacts of elephant populations on vegetation dynamics in some regions may in fact represent a shift towards a more natural historical state.8,21 Finally, much of the detrimental impacts of elephants on habitat structure and diversity, particularly at smaller scales, has resulted from human interventions (such as the erection of fences and the establishment of artificial water points) that have unnaturally confined elephants to localised areas, disrupted seasonal movements and disturbed the natural dynamics of population processes.5,13,22.
- Full Text:
- Date Issued: 2014
Electro‐oxidation of acetaminophen on nickel/poly (o‐aminophenol)/multi‐walled carbon nanotube nanocomposite modified graphite electrode.
- Naeemy, Ali, Mohammadi, Ali, Bakhtiari, Hediech, Ashouri, Nasim, Walker, Roderick B
- Authors: Naeemy, Ali , Mohammadi, Ali , Bakhtiari, Hediech , Ashouri, Nasim , Walker, Roderick B
- Date: 2014
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/184107 , vital:44173 , xlink:href="https://ietresearch.onlinelibrary.wiley.com/doi/pdf/10.1049/mnl.2014.0197"
- Description: Poly(o-aminophenol) (POAP)/multi-walled carbon nanotube (MWCNT) nanocomposite and POAP in the absence of the MWCNT were fabricated by consecutive cyclic voltammetry (CV) on a graphite (G) electrode. The dispersion of nickel (II) ions was accomplished and incorporated into the polymeric electrodes (G/POAP and G/POAP-MWCNT) by immersing them into a 0.1 M nickel (II) solution. Following preparation of G/POAP/Ni and G/POAP-MWCNT/Ni, the electrochemical behaviour was examined using CV. Scanning electron microscopy was used for characterisation of the nanocomposite. The prepared electrodes showed enhanced electrocatalytic activity for the oxidation of acetaminophen and facilitated the detection of acetaminophen in a 0.1 M NaOH solution. Compared with the G/POAP/Ni electrode, the G/POAP-MWCNT/Ni electrode had a significant current response of acetaminophen oxidation because of the synergistic effects of POAP and the MWCNT. By CV, the calibration plot was linear in the range of 1–13 mM with standard deviation between 0.3 and 6.54% for acetaminophen. The G/POAP-MWCNT/Ni was successfully applied for acetaminophen determination in tablets and the results showed sufficient precision and achieved a mean recovery of 96.8% (R.S.D. = 4.9%).
- Full Text:
- Date Issued: 2014
- Authors: Naeemy, Ali , Mohammadi, Ali , Bakhtiari, Hediech , Ashouri, Nasim , Walker, Roderick B
- Date: 2014
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/184107 , vital:44173 , xlink:href="https://ietresearch.onlinelibrary.wiley.com/doi/pdf/10.1049/mnl.2014.0197"
- Description: Poly(o-aminophenol) (POAP)/multi-walled carbon nanotube (MWCNT) nanocomposite and POAP in the absence of the MWCNT were fabricated by consecutive cyclic voltammetry (CV) on a graphite (G) electrode. The dispersion of nickel (II) ions was accomplished and incorporated into the polymeric electrodes (G/POAP and G/POAP-MWCNT) by immersing them into a 0.1 M nickel (II) solution. Following preparation of G/POAP/Ni and G/POAP-MWCNT/Ni, the electrochemical behaviour was examined using CV. Scanning electron microscopy was used for characterisation of the nanocomposite. The prepared electrodes showed enhanced electrocatalytic activity for the oxidation of acetaminophen and facilitated the detection of acetaminophen in a 0.1 M NaOH solution. Compared with the G/POAP/Ni electrode, the G/POAP-MWCNT/Ni electrode had a significant current response of acetaminophen oxidation because of the synergistic effects of POAP and the MWCNT. By CV, the calibration plot was linear in the range of 1–13 mM with standard deviation between 0.3 and 6.54% for acetaminophen. The G/POAP-MWCNT/Ni was successfully applied for acetaminophen determination in tablets and the results showed sufficient precision and achieved a mean recovery of 96.8% (R.S.D. = 4.9%).
- Full Text:
- Date Issued: 2014
Electrospun fiber based colorimetric probes for aspartate aminotransferase and I7ß-estradiol
- Authors: Pule, Bellah Oreeditse
- Date: 2014
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/54869 , vital:26623
- Description: Fabrication, characterization and application of electrospun polymer composite based colorimetric probes are presented in this thesis. The first part of the thesis involved the development of a protocol for in situ reduction of gold trication (Au³+) into metallic gold atoms with sodium borohydride. The prepared PS-Au NPs showed an SPR band at 542 nm. Furthermore the absorbance of the colloidal Au NPs in polystyrene exhibited a good linear correlation (r2 = 0.9934) to E2 concentration in the range 5 to 50 ppb. The lowest naked eye detection limit was found to be 0.5 ppb and could further be easily monitored by UV-vis spectrophotometer. Upon interaction with E2 Au NPs aggregated to give nanoparticle clusters, confirmed through TEM analysis. Different concentrations of Au NPs were found to have a significant effect on the conductivity of the PS-Au NPs solution. At low concentrations of Au NPs (0.002, 0.015 and 0.025% w/v) PS-Au NPs solution could be electrospun without clogging. The FE-SEM images showed a non-beaded morphology of PS-Au NPs composite fibers. Upon interaction of the colorimetric probe strips with various E2 concentrations it was observed that with increasing E2 concentrations (50 ng/ml to 1000 µg/ml) the colour of the probe changed gradually from white to shades of pink and eventually to shades of blue at higher E2 concentrations. The visible cut-off concentration was 100 ng/ml. The second component of the thesis focussed on the development of diazonium dye-nylon 6 colorimetric probe for aspartate aminotransferase. At optimal pH 7.4 the enzyme was stable, highly active and catalyzed a reaction that was susceptible to detailed kinetic analysis by continuous optical methods. The KM values for L-aspartate, a- ketoglutarate and oxaloacetate were 2.60, 0.59 and 0.066 mM, respectively. On the basis of these KM values the solid-state colorimetric probe was developed. A colour change occurred when an electrospun dye-N 6 probes were exposed to visibly detectable concentrations of oxaloacetate, an AST-catalyzed reaction product. While monitoring AST activity at 530 run, a linear relation was obtained between oxaloacetate concentrations ranging from 0.4 - 7.4 µg/ml. Naked eye detection limit of 2.4 µg/ml oxalaoacetate equivalence of 10 times the normal AST activity was attained. The colorimetric probe was in addition, tested against co-substrates aspartate, ketoglutarate and a variety of other compounds such as alanine, pryruvate, as well as glutamic, malaic and succinic acids known to interfere with AST activity. Each compound elicited a distinct and unambiguous colour change upon interaction with the colorimetric probe. Further X-ray powder diffraction (XRD), duNouy ring tensiometer, Brunauer- Emmett- Teller (BET) and energy dispersive X-ray spectroscopy (EDS/EDX) characterization confirmed composition and stability of the colorimetric probes. Colorimetric probes developed in this thesis are relatively cost effective, simple and "rugged" for measurement of analytes with visual detection without sample pretreatment in matrices, such as plasma and dairy effluents. The probes warrant further investigation as they have shown potential and offer a promising solid-state platform for both clinical diagnostics and environmental monitoring.
- Full Text:
- Date Issued: 2014
- Authors: Pule, Bellah Oreeditse
- Date: 2014
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/54869 , vital:26623
- Description: Fabrication, characterization and application of electrospun polymer composite based colorimetric probes are presented in this thesis. The first part of the thesis involved the development of a protocol for in situ reduction of gold trication (Au³+) into metallic gold atoms with sodium borohydride. The prepared PS-Au NPs showed an SPR band at 542 nm. Furthermore the absorbance of the colloidal Au NPs in polystyrene exhibited a good linear correlation (r2 = 0.9934) to E2 concentration in the range 5 to 50 ppb. The lowest naked eye detection limit was found to be 0.5 ppb and could further be easily monitored by UV-vis spectrophotometer. Upon interaction with E2 Au NPs aggregated to give nanoparticle clusters, confirmed through TEM analysis. Different concentrations of Au NPs were found to have a significant effect on the conductivity of the PS-Au NPs solution. At low concentrations of Au NPs (0.002, 0.015 and 0.025% w/v) PS-Au NPs solution could be electrospun without clogging. The FE-SEM images showed a non-beaded morphology of PS-Au NPs composite fibers. Upon interaction of the colorimetric probe strips with various E2 concentrations it was observed that with increasing E2 concentrations (50 ng/ml to 1000 µg/ml) the colour of the probe changed gradually from white to shades of pink and eventually to shades of blue at higher E2 concentrations. The visible cut-off concentration was 100 ng/ml. The second component of the thesis focussed on the development of diazonium dye-nylon 6 colorimetric probe for aspartate aminotransferase. At optimal pH 7.4 the enzyme was stable, highly active and catalyzed a reaction that was susceptible to detailed kinetic analysis by continuous optical methods. The KM values for L-aspartate, a- ketoglutarate and oxaloacetate were 2.60, 0.59 and 0.066 mM, respectively. On the basis of these KM values the solid-state colorimetric probe was developed. A colour change occurred when an electrospun dye-N 6 probes were exposed to visibly detectable concentrations of oxaloacetate, an AST-catalyzed reaction product. While monitoring AST activity at 530 run, a linear relation was obtained between oxaloacetate concentrations ranging from 0.4 - 7.4 µg/ml. Naked eye detection limit of 2.4 µg/ml oxalaoacetate equivalence of 10 times the normal AST activity was attained. The colorimetric probe was in addition, tested against co-substrates aspartate, ketoglutarate and a variety of other compounds such as alanine, pryruvate, as well as glutamic, malaic and succinic acids known to interfere with AST activity. Each compound elicited a distinct and unambiguous colour change upon interaction with the colorimetric probe. Further X-ray powder diffraction (XRD), duNouy ring tensiometer, Brunauer- Emmett- Teller (BET) and energy dispersive X-ray spectroscopy (EDS/EDX) characterization confirmed composition and stability of the colorimetric probes. Colorimetric probes developed in this thesis are relatively cost effective, simple and "rugged" for measurement of analytes with visual detection without sample pretreatment in matrices, such as plasma and dairy effluents. The probes warrant further investigation as they have shown potential and offer a promising solid-state platform for both clinical diagnostics and environmental monitoring.
- Full Text:
- Date Issued: 2014
Electropolymerized Fluorinated Aniline-Based Fiber for Headspace Solid-Phase Microextraction and Gas Chromatographic Determination of Benzaldehyde in Injectable Pharmaceutical Formulations
- Mohammadi, Ali, Mohammadi, Somayeh, Moghaddam, Bayandori A, Masoumi, Vahideh, Walker, Roderick B
- Authors: Mohammadi, Ali , Mohammadi, Somayeh , Moghaddam, Bayandori A , Masoumi, Vahideh , Walker, Roderick B
- Date: 2014
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/184120 , vital:44175 , xlink:href="https://doi.org/10.1093/chromsci/bmt152"
- Description: In this study, a simple method was developed and validated to detect trace levels of benzaldehyde in injectable pharmaceutical formulations by solid-phase microextraction coupled with gas chromatography–flame ionization detector. Polyaniline was electrodeposited on a platinum wire in trifluoroacetic acid solvent by cyclic voltammetry technique. This fiber shows high thermal and mechanical stability and high performance in extraction of benzaldehyde. Extraction and desorption time and temperature, salt effect and gas chromatography parameters were optimized as key parameters. At the optimum conditions, the fiber shows good linearity between peak area ratio of benzaldehyde/3-chlorobenzaldehyde and benzaldehyde concentration in the range of 50–800 ng/mL with percent relative standard deviation values ranging from 0.75 to 8.64% (n 5 3). The limits of quantitation and detection were 50 and 16 ng/mL, respectively. The method has the requisite selectivity, sensitivity, accuracy and precision to assay benzaldehyde in injectable pharmaceutical dosage forms.
- Full Text:
- Date Issued: 2014
- Authors: Mohammadi, Ali , Mohammadi, Somayeh , Moghaddam, Bayandori A , Masoumi, Vahideh , Walker, Roderick B
- Date: 2014
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/184120 , vital:44175 , xlink:href="https://doi.org/10.1093/chromsci/bmt152"
- Description: In this study, a simple method was developed and validated to detect trace levels of benzaldehyde in injectable pharmaceutical formulations by solid-phase microextraction coupled with gas chromatography–flame ionization detector. Polyaniline was electrodeposited on a platinum wire in trifluoroacetic acid solvent by cyclic voltammetry technique. This fiber shows high thermal and mechanical stability and high performance in extraction of benzaldehyde. Extraction and desorption time and temperature, salt effect and gas chromatography parameters were optimized as key parameters. At the optimum conditions, the fiber shows good linearity between peak area ratio of benzaldehyde/3-chlorobenzaldehyde and benzaldehyde concentration in the range of 50–800 ng/mL with percent relative standard deviation values ranging from 0.75 to 8.64% (n 5 3). The limits of quantitation and detection were 50 and 16 ng/mL, respectively. The method has the requisite selectivity, sensitivity, accuracy and precision to assay benzaldehyde in injectable pharmaceutical dosage forms.
- Full Text:
- Date Issued: 2014
Electrochemical behaviour of gold nanoparticles and Co tetraaminophthalocyanine on glassy carbon electrode
- Maringa, Audacity, Antunes, Edith M, Nyokong, Tebello
- Authors: Maringa, Audacity , Antunes, Edith M , Nyokong, Tebello
- Date: 2014
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/241573 , vital:50951 , xlink:href="https://doi.org/10.1016/j.electacta.2013.12.132"
- Description: We report on the electrodeposition of gold nanoparticles (AuNPs) onto the glassy carbon electrode (GCE) followed by polymerization of cobalt tetraamino phthalocyanine (CoPc(NH2)4) on top (represented as poly-CoPc(NH2)4-/AuNPs-GCE). The modified electrode where CoPc(NH2)4 is polymerized first followed by deposition of AuNPs is represented as AuNPs/poly-CoPc(NH2)4-GCE. In the absence of AuNPs, the electrode is represented as poly-CoPc(NH2)4-GCE or for AuNPs alone (AuNPs-GCE). The surface coverage was 1.5 × 10−9 mol cm−2 for AuNPs-GCE and 3.0 × 10−9 mol cm−2 for the rest of the modified electrodes. AuNPs/CoPc(NH2)4-GCE exhibited high electrocatalytic activity towards the oxidation of nitrite, with detection potential of 0.76 V. The catalytic rate constant of 3.96 × 107 cm3 mol−1 s−1 was obtained for nitrite oxidation.
- Full Text:
- Date Issued: 2014
- Authors: Maringa, Audacity , Antunes, Edith M , Nyokong, Tebello
- Date: 2014
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/241573 , vital:50951 , xlink:href="https://doi.org/10.1016/j.electacta.2013.12.132"
- Description: We report on the electrodeposition of gold nanoparticles (AuNPs) onto the glassy carbon electrode (GCE) followed by polymerization of cobalt tetraamino phthalocyanine (CoPc(NH2)4) on top (represented as poly-CoPc(NH2)4-/AuNPs-GCE). The modified electrode where CoPc(NH2)4 is polymerized first followed by deposition of AuNPs is represented as AuNPs/poly-CoPc(NH2)4-GCE. In the absence of AuNPs, the electrode is represented as poly-CoPc(NH2)4-GCE or for AuNPs alone (AuNPs-GCE). The surface coverage was 1.5 × 10−9 mol cm−2 for AuNPs-GCE and 3.0 × 10−9 mol cm−2 for the rest of the modified electrodes. AuNPs/CoPc(NH2)4-GCE exhibited high electrocatalytic activity towards the oxidation of nitrite, with detection potential of 0.76 V. The catalytic rate constant of 3.96 × 107 cm3 mol−1 s−1 was obtained for nitrite oxidation.
- Full Text:
- Date Issued: 2014