A laminated, emergentist view of skills ecosystems
- Ramsarup, Presha, Lotz-Sisitka, Heila, McGrath, Simon
- Authors: Ramsarup, Presha , Lotz-Sisitka, Heila , McGrath, Simon
- Date: 2022
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/370074 , vital:66295 , xlink:href="https://doi.org/10.1080/14767430.2022.2145768"
- Description: In this paper we present a model of vocational education and training (VET) that can be used to guide decisions relating to VET in Africa today. This model takes the critique of the neoclassical, neoliberal model of VET as its starting point. Guided by Bhaskar's Critical Naturalism, we use immanent critique to consider the adequacy of proposed alternatives to the neoclassical approach, such as: the heterodox approach, which foregrounds explanations based on human capital and political economy; and Hodgson and Spours' social ecosystem model, which addresses some of the limitations of the heterodox account by including, social and ecosystem elements. Finally, we offer a version of the social ecosystem model that, according to our analysis, explains more of the empirical evidence than previous models. Our version of the social ecosystem model differs from earlier versions in terms of its explicit reference to the critical realist ideas of position- practices and emergence.
- Full Text:
- Date Issued: 2022
- Authors: Ramsarup, Presha , Lotz-Sisitka, Heila , McGrath, Simon
- Date: 2022
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/370074 , vital:66295 , xlink:href="https://doi.org/10.1080/14767430.2022.2145768"
- Description: In this paper we present a model of vocational education and training (VET) that can be used to guide decisions relating to VET in Africa today. This model takes the critique of the neoclassical, neoliberal model of VET as its starting point. Guided by Bhaskar's Critical Naturalism, we use immanent critique to consider the adequacy of proposed alternatives to the neoclassical approach, such as: the heterodox approach, which foregrounds explanations based on human capital and political economy; and Hodgson and Spours' social ecosystem model, which addresses some of the limitations of the heterodox account by including, social and ecosystem elements. Finally, we offer a version of the social ecosystem model that, according to our analysis, explains more of the empirical evidence than previous models. Our version of the social ecosystem model differs from earlier versions in terms of its explicit reference to the critical realist ideas of position- practices and emergence.
- Full Text:
- Date Issued: 2022
An artificial neural network approach to predict the effects of formulation and process variables on prednisone release from a multipartite system
- Manda, Arthur, Walker, Roderick B, Khamanga, Sandile M
- Authors: Manda, Arthur , Walker, Roderick B , Khamanga, Sandile M
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/183237 , vital:43933 , xlink:href="https://doi.org/10.3390/pharmaceutics11030109"
- Description: The impact of formulation and process variables on the in-vitro release of prednisone from a multiple-unit pellet system was investigated. Box-Behnken Response Surface Methodology (RSM) was used to generate multivariate experiments. The extrusion-spheronization method was used to produce pellets and dissolution studies were performed using United States Pharmacopoeia (USP) Apparatus 2 as described in USP XXIV. Analysis of dissolution test samples was performed using a reversed-phase high-performance liquid chromatography (RP-HPLC) method. Four formulation and process variables viz., microcrystalline cellulose concentration, sodium starch glycolate concentration, spheronization time and extrusion speed were investigated and drug release, aspect ratio and yield were monitored for the trained artificial neural networks (ANN). To achieve accurate prediction, data generated from experimentation were used to train a multi-layer perceptron (MLP) using back propagation (BP) and the Broyden-Fletcher-Goldfarb-Shanno (BFGS) 57 training algorithm until a satisfactory value of root mean square error (RMSE) was observed. The study revealed that the in-vitro release profile of prednisone was significantly impacted by microcrystalline cellulose concentration and sodium starch glycolate concentration. Increasing microcrystalline cellulose concentration retarded dissolution rate whereas increasing sodium starch glycolate concentration improved dissolution rate. Spheronization time and extrusion speed had minimal impact on prednisone release but had a significant impact on extrudate and pellet quality. This work demonstrated that RSM can be successfully used concurrently with ANN for dosage form manufacture to permit the exploration of experimental regions that are omitted when using RSM alone.
- Full Text:
- Date Issued: 2019
- Authors: Manda, Arthur , Walker, Roderick B , Khamanga, Sandile M
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/183237 , vital:43933 , xlink:href="https://doi.org/10.3390/pharmaceutics11030109"
- Description: The impact of formulation and process variables on the in-vitro release of prednisone from a multiple-unit pellet system was investigated. Box-Behnken Response Surface Methodology (RSM) was used to generate multivariate experiments. The extrusion-spheronization method was used to produce pellets and dissolution studies were performed using United States Pharmacopoeia (USP) Apparatus 2 as described in USP XXIV. Analysis of dissolution test samples was performed using a reversed-phase high-performance liquid chromatography (RP-HPLC) method. Four formulation and process variables viz., microcrystalline cellulose concentration, sodium starch glycolate concentration, spheronization time and extrusion speed were investigated and drug release, aspect ratio and yield were monitored for the trained artificial neural networks (ANN). To achieve accurate prediction, data generated from experimentation were used to train a multi-layer perceptron (MLP) using back propagation (BP) and the Broyden-Fletcher-Goldfarb-Shanno (BFGS) 57 training algorithm until a satisfactory value of root mean square error (RMSE) was observed. The study revealed that the in-vitro release profile of prednisone was significantly impacted by microcrystalline cellulose concentration and sodium starch glycolate concentration. Increasing microcrystalline cellulose concentration retarded dissolution rate whereas increasing sodium starch glycolate concentration improved dissolution rate. Spheronization time and extrusion speed had minimal impact on prednisone release but had a significant impact on extrudate and pellet quality. This work demonstrated that RSM can be successfully used concurrently with ANN for dosage form manufacture to permit the exploration of experimental regions that are omitted when using RSM alone.
- Full Text:
- Date Issued: 2019
An integrated framework for assessing coastal community vulnerability across cultures, oceans and scales
- Aswani, Shankar, Howard, J A, Gasalla, Maria A, Jennings, Sarah, Malherbe, W, Martins, I M, Salim Shyam, Van Putten, Ingrid E, Swathilekshmi, P S, Narayanakumar, R, Watmough G R
- Authors: Aswani, Shankar , Howard, J A , Gasalla, Maria A , Jennings, Sarah , Malherbe, W , Martins, I M , Salim Shyam , Van Putten, Ingrid E , Swathilekshmi, P S , Narayanakumar, R , Watmough G R
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/421581 , vital:71863 , xlink:href="https://doi.org/10.1080/17565529.2018.1442795"
- Description: Coastal communities are some of the most at-risk populations with respect to climate change impacts. It is therefore important to determine the vulnerability of such communities to co-develop viable adaptation options. Global efforts to address this issue include international scientific projects, such as Global Learning for Local Solutions (GULLS), which focuses on five fast warming regions of the southern hemisphere and aims to provide an understanding of the local scale processes influencing community vulnerability that can then be up-scaled to regional, country and global levels. This paper describes the development of a new social and ecological vulnerability framework which integrates exposure, sensitivity and adaptive capacity with the social livelihoods and food security approaches. It also measures community flexibility to understand better the adaptive capacity of different levels of community organization. The translation of the conceptual framework to an implementable method is described and its application in a number of “hotspot” countries, where ocean waters are warming faster than the rest of the world, is presented. Opportunities for cross-cultural comparisons to uncover similarities and differences in vulnerability and adaptation patterns among the study’s coastal communities, which can provide accelerated learning mechanisms to other coastal regions, are highlighted. The social and ecological framework and the associated survey approach allow for future integration of local-level vulnerability data with ecological and oceanographic models.
- Full Text:
- Date Issued: 2019
- Authors: Aswani, Shankar , Howard, J A , Gasalla, Maria A , Jennings, Sarah , Malherbe, W , Martins, I M , Salim Shyam , Van Putten, Ingrid E , Swathilekshmi, P S , Narayanakumar, R , Watmough G R
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/421581 , vital:71863 , xlink:href="https://doi.org/10.1080/17565529.2018.1442795"
- Description: Coastal communities are some of the most at-risk populations with respect to climate change impacts. It is therefore important to determine the vulnerability of such communities to co-develop viable adaptation options. Global efforts to address this issue include international scientific projects, such as Global Learning for Local Solutions (GULLS), which focuses on five fast warming regions of the southern hemisphere and aims to provide an understanding of the local scale processes influencing community vulnerability that can then be up-scaled to regional, country and global levels. This paper describes the development of a new social and ecological vulnerability framework which integrates exposure, sensitivity and adaptive capacity with the social livelihoods and food security approaches. It also measures community flexibility to understand better the adaptive capacity of different levels of community organization. The translation of the conceptual framework to an implementable method is described and its application in a number of “hotspot” countries, where ocean waters are warming faster than the rest of the world, is presented. Opportunities for cross-cultural comparisons to uncover similarities and differences in vulnerability and adaptation patterns among the study’s coastal communities, which can provide accelerated learning mechanisms to other coastal regions, are highlighted. The social and ecological framework and the associated survey approach allow for future integration of local-level vulnerability data with ecological and oceanographic models.
- Full Text:
- Date Issued: 2019
Change in Roviana Lagoon Coral Reef Ethnobiology
- Aswani, Shankar, Albert, Simon
- Authors: Aswani, Shankar , Albert, Simon
- Date: 2015
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/421863 , vital:71891 , xlink:href="https://doi.org/10.1007/978-3-319-23763-3"
- Description: Coral reefs are iconic for their beauty and biodiversity, and are of great socioeconomic and cultural importance for many coastal communities across the tropics. However, little is known about people’s local classification and their social and ecological relationship with these habitats. This chapter describes Roviana people’s changing ecological and social relationship with their coral reefs, which are increasingly being damaged by humans. First, we combined ecological and social data to describe people’s classification of local coral reefs in tandem with the productive practices conducted in these habitats. Second, we examined local perceptions and recognized effects of environmental and climatic changes on reefs over the last two decades. Finally, we measured changes in fishing activities and in the taxonomic systems (between 1995 and 2011) to evaluate if recent social and economic change has led to the erosion of marine indigenous ecological knowledge and associated practices. Studying people’s changing perceptions of their coral reefs is crucial to understand their ability to identify and adapt to environmental transformations. Simply, the way local people perceive the state of the environment is not only important in terms of changes in local epistemology but also has important implications for how resources are used and managed, and this information can be coupled with scientific one for a broader management strategy.
- Full Text:
- Date Issued: 2015
- Authors: Aswani, Shankar , Albert, Simon
- Date: 2015
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/421863 , vital:71891 , xlink:href="https://doi.org/10.1007/978-3-319-23763-3"
- Description: Coral reefs are iconic for their beauty and biodiversity, and are of great socioeconomic and cultural importance for many coastal communities across the tropics. However, little is known about people’s local classification and their social and ecological relationship with these habitats. This chapter describes Roviana people’s changing ecological and social relationship with their coral reefs, which are increasingly being damaged by humans. First, we combined ecological and social data to describe people’s classification of local coral reefs in tandem with the productive practices conducted in these habitats. Second, we examined local perceptions and recognized effects of environmental and climatic changes on reefs over the last two decades. Finally, we measured changes in fishing activities and in the taxonomic systems (between 1995 and 2011) to evaluate if recent social and economic change has led to the erosion of marine indigenous ecological knowledge and associated practices. Studying people’s changing perceptions of their coral reefs is crucial to understand their ability to identify and adapt to environmental transformations. Simply, the way local people perceive the state of the environment is not only important in terms of changes in local epistemology but also has important implications for how resources are used and managed, and this information can be coupled with scientific one for a broader management strategy.
- Full Text:
- Date Issued: 2015
Change in Roviana Lagoon Coral Reef Ethnobiology
- Aswani, Shankar, Albert, Simon
- Authors: Aswani, Shankar , Albert, Simon
- Date: 2015
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/421868 , vital:71892 , xlink:href="https://doi.org/10.1007/978-3-319-23763-3"
- Description: Coral reefs are iconic for their beauty and biodiversity, and are of great socioeconomic and cultural importance for many coastal communities across the tropics. However, little is known about people’s local classification and their social and ecological relationship with these habitats. This chapter describes Roviana people’s changing ecological and social relationship with their coral reefs, which are increasingly being damaged by humans. First, we combined ecological and social data to describe people’s classification of local coral reefs in tandem with the productive practices conducted in these habitats. Second, we examined local perceptions and recognized effects of environmental and climatic changes on reefs over the last two decades. Finally, we measured changes in fishing activities and in the taxonomic systems (between 1995 and 2011) to evaluate if recent social and economic change has led to the erosion of marine indigenous ecological knowledge and associated practices. Studying people’s changing perceptions of their coral reefs is crucial to understand their ability to identify and adapt to environmental transformations. Simply, the way local people perceive the state of the environment is not only important in terms of changes in local epistemology but also has important implications for how resources are used and managed, and this information can be coupled with scientific one for a broader management strategy.
- Full Text:
- Date Issued: 2015
- Authors: Aswani, Shankar , Albert, Simon
- Date: 2015
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/421868 , vital:71892 , xlink:href="https://doi.org/10.1007/978-3-319-23763-3"
- Description: Coral reefs are iconic for their beauty and biodiversity, and are of great socioeconomic and cultural importance for many coastal communities across the tropics. However, little is known about people’s local classification and their social and ecological relationship with these habitats. This chapter describes Roviana people’s changing ecological and social relationship with their coral reefs, which are increasingly being damaged by humans. First, we combined ecological and social data to describe people’s classification of local coral reefs in tandem with the productive practices conducted in these habitats. Second, we examined local perceptions and recognized effects of environmental and climatic changes on reefs over the last two decades. Finally, we measured changes in fishing activities and in the taxonomic systems (between 1995 and 2011) to evaluate if recent social and economic change has led to the erosion of marine indigenous ecological knowledge and associated practices. Studying people’s changing perceptions of their coral reefs is crucial to understand their ability to identify and adapt to environmental transformations. Simply, the way local people perceive the state of the environment is not only important in terms of changes in local epistemology but also has important implications for how resources are used and managed, and this information can be coupled with scientific one for a broader management strategy.
- Full Text:
- Date Issued: 2015
Changes in household use and sale of locally collected environmental resources over a 15-year period in a rural village, South Africa
- Falayi, Menelisi, Shackleton, Sheona E, Kemp, Georgina Cundill, Shackleton, Charlie M
- Authors: Falayi, Menelisi , Shackleton, Sheona E , Kemp, Georgina Cundill , Shackleton, Charlie M
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/398196 , vital:69383 , xlink:href="https://doi.org/10.1080/14728028.2019.1568309"
- Description: Many rural areas are experiencing rapid social-ecological changes, impacting livelihoods and creating less certain futures. Despite several decades of research on the use of locally collected environmental resources there have been few repeat studies, especially in South and Southern Africa, to consider how households may be altering such use alongside other changes. This paper explores changes in the use of environmental resources by communities in the Kat River Valley, South Africa over a fifteen-year period, between 2000 and 2015, using a repeat survey, key informant interviews and other data from a larger study relating to social-ecological change. The proportion of households collecting different environmental resources was similar between the two periods. However, the mean quantities used per household had declined for several resources . Consequently, the monetary contribution or worth of these to livelihoods also declined, except for fuelwood and river sand. These changes can be related to, amongst others, transformations in both the local landscape and socio-economic environment, such as increases in state social welfare, a decline in agricultural production, woody plant encroachment, generational preferences, and the expansion of supermarket retailers. Understanding such trends is important for considering the sustainable management of landscapes and livelihoods into the future.
- Full Text:
- Date Issued: 2019
- Authors: Falayi, Menelisi , Shackleton, Sheona E , Kemp, Georgina Cundill , Shackleton, Charlie M
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/398196 , vital:69383 , xlink:href="https://doi.org/10.1080/14728028.2019.1568309"
- Description: Many rural areas are experiencing rapid social-ecological changes, impacting livelihoods and creating less certain futures. Despite several decades of research on the use of locally collected environmental resources there have been few repeat studies, especially in South and Southern Africa, to consider how households may be altering such use alongside other changes. This paper explores changes in the use of environmental resources by communities in the Kat River Valley, South Africa over a fifteen-year period, between 2000 and 2015, using a repeat survey, key informant interviews and other data from a larger study relating to social-ecological change. The proportion of households collecting different environmental resources was similar between the two periods. However, the mean quantities used per household had declined for several resources . Consequently, the monetary contribution or worth of these to livelihoods also declined, except for fuelwood and river sand. These changes can be related to, amongst others, transformations in both the local landscape and socio-economic environment, such as increases in state social welfare, a decline in agricultural production, woody plant encroachment, generational preferences, and the expansion of supermarket retailers. Understanding such trends is important for considering the sustainable management of landscapes and livelihoods into the future.
- Full Text:
- Date Issued: 2019
Double stimulation and transformative agency for leadership development of school learners in Southern Africa
- Authors: Grant, Carolyn
- Date: 2022
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/281035 , vital:55685 , xlink:href="https://doi.org/10.1080/14681366.2020.1805495"
- Description: Learners, because of their minor status, are a virtual absence in everyday school leadership work, particularly on the African continent. School leadership, therefore, continues to be misconceived as an adult phenomenon. Framed by Cultural Historical Activity Theory, this paper reports on a Southern African Higher Education studythat engages with the Vygotskian principle of ‘double stimulation’ and its relationship to transformative agency in the context of a school-based learner leadership development initiative. One school change project was purposively selected as the case, and data were drawn from a postgraduate student research report and self-reflective journal. Drawing on the Sannino model of double stimulation, the paper explores the phases of double stimulation as well as instances of transformative agency evident in the data, and speculates about the relationship between double stimulation and transformative agency in the leadership development of learners.
- Full Text:
- Date Issued: 2022
- Authors: Grant, Carolyn
- Date: 2022
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/281035 , vital:55685 , xlink:href="https://doi.org/10.1080/14681366.2020.1805495"
- Description: Learners, because of their minor status, are a virtual absence in everyday school leadership work, particularly on the African continent. School leadership, therefore, continues to be misconceived as an adult phenomenon. Framed by Cultural Historical Activity Theory, this paper reports on a Southern African Higher Education studythat engages with the Vygotskian principle of ‘double stimulation’ and its relationship to transformative agency in the context of a school-based learner leadership development initiative. One school change project was purposively selected as the case, and data were drawn from a postgraduate student research report and self-reflective journal. Drawing on the Sannino model of double stimulation, the paper explores the phases of double stimulation as well as instances of transformative agency evident in the data, and speculates about the relationship between double stimulation and transformative agency in the leadership development of learners.
- Full Text:
- Date Issued: 2022
Electrocatalytic and photosensitizing behavior of metallophthalocyanine complexes
- Authors: Nyokong, Tebello
- Date: 2008
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/265908 , vital:53899 , xlink:href="https://doi.org/10.1142/S1088424608000388"
- Description: Electrocatalytic or photosensitizing (photocatalytic) properties of metallophthalocyanine (MPc) complexes are dependent on the central metal. Electrocatalytic behavior is observed for electroactive central metals such as Co, Mn and Fe, whereas photosensitizing behavior is observed for diamagnetic metals such as Al, Zn and Si. In the presence of nanoparticles such as quantum dots, the photosensitizing behavior of MPc complexes is improved. Carbon nanotubes enhance the electrocatalytic behavior of MPc complexes.
- Full Text:
- Date Issued: 2008
- Authors: Nyokong, Tebello
- Date: 2008
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/265908 , vital:53899 , xlink:href="https://doi.org/10.1142/S1088424608000388"
- Description: Electrocatalytic or photosensitizing (photocatalytic) properties of metallophthalocyanine (MPc) complexes are dependent on the central metal. Electrocatalytic behavior is observed for electroactive central metals such as Co, Mn and Fe, whereas photosensitizing behavior is observed for diamagnetic metals such as Al, Zn and Si. In the presence of nanoparticles such as quantum dots, the photosensitizing behavior of MPc complexes is improved. Carbon nanotubes enhance the electrocatalytic behavior of MPc complexes.
- Full Text:
- Date Issued: 2008
Expansive learning in the leadership development of school learners
- Grant, Carolyn, Kajee, Farhana Amod
- Authors: Grant, Carolyn , Kajee, Farhana Amod
- Date: 2020
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/281072 , vital:55689 , xlink:href="https://doi.org/10.1080/13603124.2020.1836405"
- Description: In many countries across the globe, and on the African continent in particular, young people do not have a voice in matters concerning their schooling. By virtue of their minor status, opportunities for participatory decision-making and leadership in schools are restricted, despite national policies to the contrary. This is all-too-often because leadership is (mis)understood as an adult phenomenon. In this article, we present a formative intervention, ‘Learners Lead’, which aimed at developing learner voice and leadership in learners through collective involvement in school change projects. Formulated as a documentary case study, data were generated from 95 research reports, the written assessments of the students registered for the Educational Leadership and Management elective within a postgraduate qualification in a South African university. Analysis drew on the pyramid of learner voice and the theory of expansive learning to examine if, and how, leadership development in learners occurred. The study found that expansive learning’s seven learning actions provided the necessary additional theoretical tools for understanding and unpacking the stages of leadership development as the school change projects unfolded. Implications for practice and research are discussed.
- Full Text:
- Date Issued: 2020
- Authors: Grant, Carolyn , Kajee, Farhana Amod
- Date: 2020
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/281072 , vital:55689 , xlink:href="https://doi.org/10.1080/13603124.2020.1836405"
- Description: In many countries across the globe, and on the African continent in particular, young people do not have a voice in matters concerning their schooling. By virtue of their minor status, opportunities for participatory decision-making and leadership in schools are restricted, despite national policies to the contrary. This is all-too-often because leadership is (mis)understood as an adult phenomenon. In this article, we present a formative intervention, ‘Learners Lead’, which aimed at developing learner voice and leadership in learners through collective involvement in school change projects. Formulated as a documentary case study, data were generated from 95 research reports, the written assessments of the students registered for the Educational Leadership and Management elective within a postgraduate qualification in a South African university. Analysis drew on the pyramid of learner voice and the theory of expansive learning to examine if, and how, leadership development in learners occurred. The study found that expansive learning’s seven learning actions provided the necessary additional theoretical tools for understanding and unpacking the stages of leadership development as the school change projects unfolded. Implications for practice and research are discussed.
- Full Text:
- Date Issued: 2020
Exploring the potential of developmental work research and change laboratory to support sustainability transformations: a case study of organic agriculture in Zimbabwe
- Mukute, Mutizwa, Mudokwani, Kuda, McAllistair, Georgina, Nyikahadzoi, Kefasi
- Authors: Mukute, Mutizwa , Mudokwani, Kuda , McAllistair, Georgina , Nyikahadzoi, Kefasi
- Date: 2018
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/392119 , vital:68723 , xlink:href="https://doi.org/10.1080/10749039.2018.1451542"
- Description: This paper explores the emergence of transgressive learning in CHAT-informed development work research in a networked organic agriculture case study in Zimbabwe, based on intervention research involving district organic associations tackling interconnected issues of climate change, water, food security and solidarity. The study established that We change laboratories can be used to support transgressive learning through: confronting unproductive local norms; collective reframing of problematic issues; stimulating expansive learning and sustainability transformations in minds, relationships and landscapes across time. The study also confirms the need for fourth generation CHAT to address the complex social-ecological problems of today.
- Full Text:
- Date Issued: 2018
- Authors: Mukute, Mutizwa , Mudokwani, Kuda , McAllistair, Georgina , Nyikahadzoi, Kefasi
- Date: 2018
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/392119 , vital:68723 , xlink:href="https://doi.org/10.1080/10749039.2018.1451542"
- Description: This paper explores the emergence of transgressive learning in CHAT-informed development work research in a networked organic agriculture case study in Zimbabwe, based on intervention research involving district organic associations tackling interconnected issues of climate change, water, food security and solidarity. The study established that We change laboratories can be used to support transgressive learning through: confronting unproductive local norms; collective reframing of problematic issues; stimulating expansive learning and sustainability transformations in minds, relationships and landscapes across time. The study also confirms the need for fourth generation CHAT to address the complex social-ecological problems of today.
- Full Text:
- Date Issued: 2018
Grasses as suitable targets for classical weed biological control
- Sutton, Guy F, Day, Michael D, Den Breeyen, Alana, Goolsby, J A, Cristofaro, M, McConnachie, Andrew J, Paterson, Iain D
- Authors: Sutton, Guy F , Day, Michael D , Den Breeyen, Alana , Goolsby, J A , Cristofaro, M , McConnachie, Andrew J , Paterson, Iain D
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/417984 , vital:71499 , xlink:href="https://doi.org/10.1007/s10526-019-09968-8"
- Description: Grasses are amongst the most abundant and environmentally damaging invasive weeds worldwide. Biological control is frequently employed as a sustainable and cost-effective management strategy for many weeds. However, grasses have not been actively pursued as targets for classical weed biological control due to a perceived lack of sufficiently specialised and damaging natural enemies to use as biological control agents. There are also concerns that the risk posed to economically important crop/pasture species and closely-related native species is too great to consider implementing biological control for invasive grasses. In this paper, we review the literature and demonstrate that grasses can possess suitably host-specific and damaging natural enemies to warrant consideration as potential biological control agents. The risk of grass biological control is no greater than for other weedy taxa if practitioners follow appropriately rigorous risk assessments protocols.
- Full Text:
- Date Issued: 2019
- Authors: Sutton, Guy F , Day, Michael D , Den Breeyen, Alana , Goolsby, J A , Cristofaro, M , McConnachie, Andrew J , Paterson, Iain D
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/417984 , vital:71499 , xlink:href="https://doi.org/10.1007/s10526-019-09968-8"
- Description: Grasses are amongst the most abundant and environmentally damaging invasive weeds worldwide. Biological control is frequently employed as a sustainable and cost-effective management strategy for many weeds. However, grasses have not been actively pursued as targets for classical weed biological control due to a perceived lack of sufficiently specialised and damaging natural enemies to use as biological control agents. There are also concerns that the risk posed to economically important crop/pasture species and closely-related native species is too great to consider implementing biological control for invasive grasses. In this paper, we review the literature and demonstrate that grasses can possess suitably host-specific and damaging natural enemies to warrant consideration as potential biological control agents. The risk of grass biological control is no greater than for other weedy taxa if practitioners follow appropriately rigorous risk assessments protocols.
- Full Text:
- Date Issued: 2019
Harvesting impacts on commonly used medicinal tree species (Catha edulis and Rapanea melanophloeos) under different land management regimes in the Mpumalanga Lowveld, South Africa
- Botha, Jenny, Witkowski, Ed T F, Shackleton, Charlie M
- Authors: Botha, Jenny , Witkowski, Ed T F , Shackleton, Charlie M
- Date: 2004
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/181379 , vital:43728 , xlink:href="https://doi.org/10.4102/koedoe.v47i2.77"
- Description: Harvesting of products from plants in the wild is widespread throughout southern Africa. Particularly important products are plant parts used in traditional medicine. However, the impacts of harvesting practices are rarely quantified, with as yet insufficient generic rules across species and life forms. This limits the predictive ability to monitor and manage the affected populations. This paper examines the harvesting impact on two popular woody medicinal species used throughout sub-Saharan Africa, namely Catha edulis (Vahl) Forssk. ex Endl. (bushman’s tea) and Rapanea melanophloeos (L.) Mez. (Cape beech). In both species, basal diameters, heights, and the number of size classes in the harvested populations were lower than in unharvested. Densities of harvested populations were higher in both species, including densities of young plants, but the frequency of individuals in larger size classes was lower. The populations of both species being harvested for medicinal products appeared to be withstanding the current levels of harvesting, but the population structure of C. edulis populations being harvested for poles on the roadside and near human settlements had been substantially altered. Despite the resilience of the two species to harvesting for medicinal products, loss of habitat or changes in land use pose a threat to a number of the assessed populations.
- Full Text:
- Date Issued: 2004
- Authors: Botha, Jenny , Witkowski, Ed T F , Shackleton, Charlie M
- Date: 2004
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/181379 , vital:43728 , xlink:href="https://doi.org/10.4102/koedoe.v47i2.77"
- Description: Harvesting of products from plants in the wild is widespread throughout southern Africa. Particularly important products are plant parts used in traditional medicine. However, the impacts of harvesting practices are rarely quantified, with as yet insufficient generic rules across species and life forms. This limits the predictive ability to monitor and manage the affected populations. This paper examines the harvesting impact on two popular woody medicinal species used throughout sub-Saharan Africa, namely Catha edulis (Vahl) Forssk. ex Endl. (bushman’s tea) and Rapanea melanophloeos (L.) Mez. (Cape beech). In both species, basal diameters, heights, and the number of size classes in the harvested populations were lower than in unharvested. Densities of harvested populations were higher in both species, including densities of young plants, but the frequency of individuals in larger size classes was lower. The populations of both species being harvested for medicinal products appeared to be withstanding the current levels of harvesting, but the population structure of C. edulis populations being harvested for poles on the roadside and near human settlements had been substantially altered. Despite the resilience of the two species to harvesting for medicinal products, loss of habitat or changes in land use pose a threat to a number of the assessed populations.
- Full Text:
- Date Issued: 2004
In vitro cytotoxic effects of chemical constituents of Euphorbia grandicornis Blanc against breast cancer cells
- Kemboi, Douglas, Peter, Xolani, Langat, Moses K, Mhlanga, Richwell, Vukea, Nyeleti, de la Mare, Jo-Anne, Siwe-Noundou, Xavier, Krause, Rui W M, Tembu, Vuyelwa J
- Authors: Kemboi, Douglas , Peter, Xolani , Langat, Moses K , Mhlanga, Richwell , Vukea, Nyeleti , de la Mare, Jo-Anne , Siwe-Noundou, Xavier , Krause, Rui W M , Tembu, Vuyelwa J
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/191747 , vital:45160 , xlink:href="https://doi.org/10.1016/j.sciaf.2021.e01002"
- Description: Euphorbia grandicornis Blanc is widely utilized in traditional medicine for a variety of ailments including body pains associated with skin irritations, inflammation, and snake or scorpion bites. Compounds from E. grandicornis were characterized using spectroscopic techniques, NMR, IR, MS, and melting points and alongside the extracts were evaluated for in vitro anticancer activity against several cancer cell lines. The root extract afforded known, β-glutinol (1), β-amyrin (2), 24-methylenetirucalla-8-en-3β-ol (3), tirucalla-8,25-diene-3β,24R-diol (4), stigmasterol (5), sitosterol (6), and hexyl (E)-3-(4-hydroxy-3-methoxyphenyl)-2-propenoate (7) based on their NMR spectroscopic data for the first report in E. grandicornis. The extracts and isolated compounds were evaluated for anticancer activities against hormone receptor-positive breast cancer (MCF-7), triple-negative breast cancer (HCC70), and non-tumorigenic mammary epithelial (MCF-12A) cell lines. The CH2Cl2 extract exhibited potent, cytotoxicity against MCF-7, HCC70, and MCF-12A cells. The aerial extract exhibited IC50 values of 1.03, 0.301, and 1.68 µg/mL, and root extract displayed IC50 values of 0.83, 0.83 and 3.98 µg/mL against MCF-7, HCC70, and MCF-12A cells respectively. The root extract thus showed selectivity for the cancer cell lines over the non-cancerous control cell line (SI = 4.80). Hexyl (E)-3-(4-hydroxy-3-methoxyphenyl)-2-propenoate (7) showed significant activity with IC50 values of 23.41, 29.45 and 27.01 µM against MCF-7, HCC70 and MCF-12A cells respectively, suggesting non-specific cytotoxicity.
- Full Text:
- Date Issued: 2021
- Authors: Kemboi, Douglas , Peter, Xolani , Langat, Moses K , Mhlanga, Richwell , Vukea, Nyeleti , de la Mare, Jo-Anne , Siwe-Noundou, Xavier , Krause, Rui W M , Tembu, Vuyelwa J
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/191747 , vital:45160 , xlink:href="https://doi.org/10.1016/j.sciaf.2021.e01002"
- Description: Euphorbia grandicornis Blanc is widely utilized in traditional medicine for a variety of ailments including body pains associated with skin irritations, inflammation, and snake or scorpion bites. Compounds from E. grandicornis were characterized using spectroscopic techniques, NMR, IR, MS, and melting points and alongside the extracts were evaluated for in vitro anticancer activity against several cancer cell lines. The root extract afforded known, β-glutinol (1), β-amyrin (2), 24-methylenetirucalla-8-en-3β-ol (3), tirucalla-8,25-diene-3β,24R-diol (4), stigmasterol (5), sitosterol (6), and hexyl (E)-3-(4-hydroxy-3-methoxyphenyl)-2-propenoate (7) based on their NMR spectroscopic data for the first report in E. grandicornis. The extracts and isolated compounds were evaluated for anticancer activities against hormone receptor-positive breast cancer (MCF-7), triple-negative breast cancer (HCC70), and non-tumorigenic mammary epithelial (MCF-12A) cell lines. The CH2Cl2 extract exhibited potent, cytotoxicity against MCF-7, HCC70, and MCF-12A cells. The aerial extract exhibited IC50 values of 1.03, 0.301, and 1.68 µg/mL, and root extract displayed IC50 values of 0.83, 0.83 and 3.98 µg/mL against MCF-7, HCC70, and MCF-12A cells respectively. The root extract thus showed selectivity for the cancer cell lines over the non-cancerous control cell line (SI = 4.80). Hexyl (E)-3-(4-hydroxy-3-methoxyphenyl)-2-propenoate (7) showed significant activity with IC50 values of 23.41, 29.45 and 27.01 µM against MCF-7, HCC70 and MCF-12A cells respectively, suggesting non-specific cytotoxicity.
- Full Text:
- Date Issued: 2021
Influence of nanoparticle materials on the photophysical behavior of phthalocyanines
- Nyokong, Tebello, Antunes, Edith M
- Authors: Nyokong, Tebello , Antunes, Edith M
- Date: 2013
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/190450 , vital:44995 , xlink:href="https://doi.org/10.1016/j.ccr.2013.03.016"
- Description: This review presents recent data on the photophysical behavior of phthalocyanines when conjugated to quantum dots, gold and magnetic nanoparticles. In some cases such conjugates offer the possibility of being used in “combination therapy”, where two or more substances may be used for treating one disease. The review focuses on the effect that the presence of nanoparticles has on the excited and triplet state parameters of the phthalocyanines. Five tables listing these parameters are presented.
- Full Text:
- Date Issued: 2013
- Authors: Nyokong, Tebello , Antunes, Edith M
- Date: 2013
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/190450 , vital:44995 , xlink:href="https://doi.org/10.1016/j.ccr.2013.03.016"
- Description: This review presents recent data on the photophysical behavior of phthalocyanines when conjugated to quantum dots, gold and magnetic nanoparticles. In some cases such conjugates offer the possibility of being used in “combination therapy”, where two or more substances may be used for treating one disease. The review focuses on the effect that the presence of nanoparticles has on the excited and triplet state parameters of the phthalocyanines. Five tables listing these parameters are presented.
- Full Text:
- Date Issued: 2013
Local knowledge on the uses, habitat, and change in abundance of multipurpose mimusops species in Benin
- Sinasson Gisèle K, Shackleton, Charlie M, Assogbadjo, Achille E, Sinsin, Brice
- Authors: Sinasson Gisèle K , Shackleton, Charlie M , Assogbadjo, Achille E , Sinsin, Brice
- Date: 2017
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/181105 , vital:43699 , xlink:href="https://doi.org/10.1007/s12231-017-9370-6"
- Description: Multipurpose NTFP species typically experience higher harvest demand because of their multiple uses, which, when combined with unsustainable land use practices, may threaten population viability. We assessed local knowledge on the uses, habitat, and population status of Mimusops andongensis and Mimusops kummel, both multipurpose NTFP species in Benin, to promote their valorization and conservation and thus sustain local knowledge on their uses for domestication issues. One hundred households were randomly selected for structured interviews for M. andongensis and 500 for M. kummel. The relationship between age, sex, and ethnic groups and the species uses was assessed using comparison and correspondence analyses. Nearly all organs of the species were used. Both species were mainly exploited for medicinal purposes but also in construction and as firewood. We found similarities in some uses of the species organs, although the species occur in different ecological zones and are used by different ethnic groups. This result should be considered for the valorization of the species. Most informants reported that populations of M. andongensis were decreasing, although some felt that they were increasing, whereas less than one-third said that M. kummel was decreasing. There were strong relationships between gender, age, and ethnic affiliation of the users and the exploited organs of both species. Potential uses exist based on both the past and current uses of the species and in comparison to other countries where they are exploited. Local ethnoecological knowledge and practices will help to valorize and conserve the species. However, further research on the species’ seed germination and propagation ability are also necessary.
- Full Text:
- Date Issued: 2017
- Authors: Sinasson Gisèle K , Shackleton, Charlie M , Assogbadjo, Achille E , Sinsin, Brice
- Date: 2017
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/181105 , vital:43699 , xlink:href="https://doi.org/10.1007/s12231-017-9370-6"
- Description: Multipurpose NTFP species typically experience higher harvest demand because of their multiple uses, which, when combined with unsustainable land use practices, may threaten population viability. We assessed local knowledge on the uses, habitat, and population status of Mimusops andongensis and Mimusops kummel, both multipurpose NTFP species in Benin, to promote their valorization and conservation and thus sustain local knowledge on their uses for domestication issues. One hundred households were randomly selected for structured interviews for M. andongensis and 500 for M. kummel. The relationship between age, sex, and ethnic groups and the species uses was assessed using comparison and correspondence analyses. Nearly all organs of the species were used. Both species were mainly exploited for medicinal purposes but also in construction and as firewood. We found similarities in some uses of the species organs, although the species occur in different ecological zones and are used by different ethnic groups. This result should be considered for the valorization of the species. Most informants reported that populations of M. andongensis were decreasing, although some felt that they were increasing, whereas less than one-third said that M. kummel was decreasing. There were strong relationships between gender, age, and ethnic affiliation of the users and the exploited organs of both species. Potential uses exist based on both the past and current uses of the species and in comparison to other countries where they are exploited. Local ethnoecological knowledge and practices will help to valorize and conserve the species. However, further research on the species’ seed germination and propagation ability are also necessary.
- Full Text:
- Date Issued: 2017
Navigating non-sense by exemplifying situated life experience and intergenerational heritage knowledge in Education for Sustainable Development learning spaces
- O'Donoghue, Rob B, Kibuka-Sebitosi, Esther, Tshiningayamwe, Sirkka A N, Palmer, Carl
- Authors: O'Donoghue, Rob B , Kibuka-Sebitosi, Esther , Tshiningayamwe, Sirkka A N , Palmer, Carl
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/388122 , vital:68308 , xlink:href="https://www.ajol.info/index.php/sajee/article/view/186410"
- Description: This paper uses an activity system perspective to probe the related problems of knowledge abstraction and a lack of relevance as a modern legacy of colonial education practices in Africa. Its purpose is to contemplate Education for Sustainable Development (ESD) pedagogy to support learning that might be better situated in and resonate with local African contexts and the emerging sustainability concerns in everyday life. Colonial education trajectories and the recent inclusion of new environmental knowledge in African curriculum and civic learning contexts are examined. This points to how circulating environment and sustainability knowledge is being constituted in disciplinary fields as abstract concepts that are often difficult to relate to local sustainability concerns. Socio-cultural heritage and intergenerational meaning making are explored to uncover better situated ways of navigating much of the abstract ‘non-sense’ confronting African learners in many modern education contexts today. Illustrative examples of historical patterns of exclusion are scoped and two cases of pedagogical innovation are examined to contemplate how to navigate better situated and more relevant learning processes. Enacted in situated and co-engaged ways, ESD practices may enable the socio-cultural capital and environmental realities of local social-ecological contexts to articulate with better situated sustainability propositions for transitioning to more peaceful, just and sustainable futures.
- Full Text:
- Date Issued: 2019
- Authors: O'Donoghue, Rob B , Kibuka-Sebitosi, Esther , Tshiningayamwe, Sirkka A N , Palmer, Carl
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/388122 , vital:68308 , xlink:href="https://www.ajol.info/index.php/sajee/article/view/186410"
- Description: This paper uses an activity system perspective to probe the related problems of knowledge abstraction and a lack of relevance as a modern legacy of colonial education practices in Africa. Its purpose is to contemplate Education for Sustainable Development (ESD) pedagogy to support learning that might be better situated in and resonate with local African contexts and the emerging sustainability concerns in everyday life. Colonial education trajectories and the recent inclusion of new environmental knowledge in African curriculum and civic learning contexts are examined. This points to how circulating environment and sustainability knowledge is being constituted in disciplinary fields as abstract concepts that are often difficult to relate to local sustainability concerns. Socio-cultural heritage and intergenerational meaning making are explored to uncover better situated ways of navigating much of the abstract ‘non-sense’ confronting African learners in many modern education contexts today. Illustrative examples of historical patterns of exclusion are scoped and two cases of pedagogical innovation are examined to contemplate how to navigate better situated and more relevant learning processes. Enacted in situated and co-engaged ways, ESD practices may enable the socio-cultural capital and environmental realities of local social-ecological contexts to articulate with better situated sustainability propositions for transitioning to more peaceful, just and sustainable futures.
- Full Text:
- Date Issued: 2019
Prospects for the biological control of Northern Temperate Weeds in South Africa
- Authors: Martin, Grant D
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/414478 , vital:71151 , xlink:href="https://hdl.handle.net/10520/ejc-ento_v29_n3_a10"
- Description: The Northern Temperate Weeds programme is a novel biological control (biocontrol) programme started in 2017, with the aim of reducing the impacts of northern temperate weeds that are common, widespread and problematic in the high elevation grasslands of South Africa. As these regions are the most important systems for water security, providing nearly 50% of all water run-off, it is surprising that these species were not targeted for biocontrol previously. Thus far, research has focused on biocontrol feasibility as well as ecological and socio-economic impact studies on several northern temperate weeds, including Pyracantha angustifolia (Franch.) C.K.Schneid, Rosa rubiginosa L., Cotoneaster spp., Rubus spp., (all Rosaceae) and Salix spp. (Salicaceae). In addition, research conducted in the USA and Europe on the natural enemies associated with two of these species, Robinia pseudoacacia L. and Gleditsia triacanthos L. (both Fabaceae and native to the USA), have provided South African researchers with the necessary foundation to initiate programmes against these weeds. Research in South Africa is currently focused on pre-release studies on R. pseudoacacia, using the leaf miner Odontota dorsalis Thunberg (Coleoptera: Chrysomelidae) and the black locust midge Obolodiplosis robiniae Haldeman (Diptera: Cecidomyiidae), and on G. triacanthos, using a seed bruchid, Amblycerus robiniae F. (Coleoptera: Chrysomelidae). Progress with these programmes and potential constraints that may limit success, are discussed.
- Full Text:
- Date Issued: 2021
- Authors: Martin, Grant D
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/414478 , vital:71151 , xlink:href="https://hdl.handle.net/10520/ejc-ento_v29_n3_a10"
- Description: The Northern Temperate Weeds programme is a novel biological control (biocontrol) programme started in 2017, with the aim of reducing the impacts of northern temperate weeds that are common, widespread and problematic in the high elevation grasslands of South Africa. As these regions are the most important systems for water security, providing nearly 50% of all water run-off, it is surprising that these species were not targeted for biocontrol previously. Thus far, research has focused on biocontrol feasibility as well as ecological and socio-economic impact studies on several northern temperate weeds, including Pyracantha angustifolia (Franch.) C.K.Schneid, Rosa rubiginosa L., Cotoneaster spp., Rubus spp., (all Rosaceae) and Salix spp. (Salicaceae). In addition, research conducted in the USA and Europe on the natural enemies associated with two of these species, Robinia pseudoacacia L. and Gleditsia triacanthos L. (both Fabaceae and native to the USA), have provided South African researchers with the necessary foundation to initiate programmes against these weeds. Research in South Africa is currently focused on pre-release studies on R. pseudoacacia, using the leaf miner Odontota dorsalis Thunberg (Coleoptera: Chrysomelidae) and the black locust midge Obolodiplosis robiniae Haldeman (Diptera: Cecidomyiidae), and on G. triacanthos, using a seed bruchid, Amblycerus robiniae F. (Coleoptera: Chrysomelidae). Progress with these programmes and potential constraints that may limit success, are discussed.
- Full Text:
- Date Issued: 2021
Synthesis and characterization of Na (Y, Gd) F4 upconversion nanoparticles and an investigation of their effects on the photophysical properties of an unsubstituted tetrathiophenoxy phthalocyanine
- Taylor, Jessica M, Litwinski, Christian, Nyokong, Tebello, Antunes, Edith M
- Authors: Taylor, Jessica M , Litwinski, Christian , Nyokong, Tebello , Antunes, Edith M
- Date: 2015
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/241437 , vital:50939 , xlink:href="https://doi.org/10.1007/s11051-015-2889-5"
- Description: Sphere- and star-shaped Na(Y,Gd)F4:Yb/Er(Tm)upconversion nanoparticles (UCNP) were successfully synthesized utilizing a methanol-assisted thermal decomposition approach and their spectroscopic (absorption, emission and luminescence lifetime) properties fully characterized. The factors affecting the size and shape of the UCNPs were studied and discussed in detail. The size of the nanoparticles was determined using TEM primarily and found to be approximately 19 and 30 nm for the Er and Tm spheres, respectively, while the Er and Tm “stars” were found to be much larger with sizes ranging from 110 to 240 nm, respectively (as determined along the width of the nanoparticle). In addition, their influence on the spectroscopic properties of an unsubstituted tetrathiophenoxy phthalocyanine (H2Pc) was investigated. The UCNP were found to produce characteristic upconversion luminescence emissions in the blue, green, red and NIR regions. Simple mixing with an H2Pc in toluene was found to exert no obvious changes in the spectroscopic properties of the Pc, although a considerable increase in the radiative lifetimes is observed for the Pc in the presence of the UCNPs. The singlet oxygen generation mediated by the red light excitation of the H2Pc mixed with UCNP was found to decrease in the presence of the NPs.
- Full Text:
- Date Issued: 2015
- Authors: Taylor, Jessica M , Litwinski, Christian , Nyokong, Tebello , Antunes, Edith M
- Date: 2015
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/241437 , vital:50939 , xlink:href="https://doi.org/10.1007/s11051-015-2889-5"
- Description: Sphere- and star-shaped Na(Y,Gd)F4:Yb/Er(Tm)upconversion nanoparticles (UCNP) were successfully synthesized utilizing a methanol-assisted thermal decomposition approach and their spectroscopic (absorption, emission and luminescence lifetime) properties fully characterized. The factors affecting the size and shape of the UCNPs were studied and discussed in detail. The size of the nanoparticles was determined using TEM primarily and found to be approximately 19 and 30 nm for the Er and Tm spheres, respectively, while the Er and Tm “stars” were found to be much larger with sizes ranging from 110 to 240 nm, respectively (as determined along the width of the nanoparticle). In addition, their influence on the spectroscopic properties of an unsubstituted tetrathiophenoxy phthalocyanine (H2Pc) was investigated. The UCNP were found to produce characteristic upconversion luminescence emissions in the blue, green, red and NIR regions. Simple mixing with an H2Pc in toluene was found to exert no obvious changes in the spectroscopic properties of the Pc, although a considerable increase in the radiative lifetimes is observed for the Pc in the presence of the UCNPs. The singlet oxygen generation mediated by the red light excitation of the H2Pc mixed with UCNP was found to decrease in the presence of the NPs.
- Full Text:
- Date Issued: 2015
The Condictio Indebiti and Unjust Factors (1)
- Authors: Glover, Graham B
- Date: 2006
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/186869 , vital:44541 , xlink:href="file:///C:/Users/User/Downloads/69THRHR419%20(2).pdf"
- Description: Since the Supreme Court of Appeal has continued to avoid taking the step of recognising a general enrichment action,' the traditional enrichment actions of the common law remain fundamentally important to the operation of the law of unjustified enrichment in South Africa. Most significant of these is the condictio indebiti, which is probably the most well-known and liberally utilised enrichment action in South African law.2 In this article, the nature and scope of this condictio will be examined, and it will be shown that it has grown beyond its notionally traditional role of reversing payments or transfers made unjustifiably by mistake, to include causes of action in duress and protest. The implications of this for the condictio, as well as for the foundations of our enrichment law will then be examined, with reference to the two leading schools of enrichment law: the civilian school, typified by German law, and the common-law school, typified by English law.
- Full Text:
- Date Issued: 2006
- Authors: Glover, Graham B
- Date: 2006
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/186869 , vital:44541 , xlink:href="file:///C:/Users/User/Downloads/69THRHR419%20(2).pdf"
- Description: Since the Supreme Court of Appeal has continued to avoid taking the step of recognising a general enrichment action,' the traditional enrichment actions of the common law remain fundamentally important to the operation of the law of unjustified enrichment in South Africa. Most significant of these is the condictio indebiti, which is probably the most well-known and liberally utilised enrichment action in South African law.2 In this article, the nature and scope of this condictio will be examined, and it will be shown that it has grown beyond its notionally traditional role of reversing payments or transfers made unjustifiably by mistake, to include causes of action in duress and protest. The implications of this for the condictio, as well as for the foundations of our enrichment law will then be examined, with reference to the two leading schools of enrichment law: the civilian school, typified by German law, and the common-law school, typified by English law.
- Full Text:
- Date Issued: 2006
The Condictio Indebiti and Unjust Factors (2)
- Authors: Glover, Graham B
- Date: 2006
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/186880 , vital:44544 , xlink:href="///C:/Users/User/Downloads/69THRHR561%20(1).pdf"
- Description: Since the Supreme Court of Appeal has continued to avoid taking the step of recognising a general enrichment action,' the traditional enrichment actions of the common law remain fundamentally important to the operation of the law of unjustified enrichment in South Africa. Most significant of these is the condictio indebiti, which is probably the most well-known and liberally utilised enrichment action in South African law.2 In this article, the nature and scope of this condictio will be examined, and it will be shown that it has grown beyond its notionally traditional role of reversing payments or transfers made unjustifiably by mistake, to include causes of action in duress and protest. The implications of this for the condictio, as well as for the foundations of our enrichment law will then be examined, with reference to the two leading schools of enrichment law: the civilian school, typified by German law, and the common-law school, typified by English law.
- Full Text:
- Date Issued: 2006
- Authors: Glover, Graham B
- Date: 2006
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/186880 , vital:44544 , xlink:href="///C:/Users/User/Downloads/69THRHR561%20(1).pdf"
- Description: Since the Supreme Court of Appeal has continued to avoid taking the step of recognising a general enrichment action,' the traditional enrichment actions of the common law remain fundamentally important to the operation of the law of unjustified enrichment in South Africa. Most significant of these is the condictio indebiti, which is probably the most well-known and liberally utilised enrichment action in South African law.2 In this article, the nature and scope of this condictio will be examined, and it will be shown that it has grown beyond its notionally traditional role of reversing payments or transfers made unjustifiably by mistake, to include causes of action in duress and protest. The implications of this for the condictio, as well as for the foundations of our enrichment law will then be examined, with reference to the two leading schools of enrichment law: the civilian school, typified by German law, and the common-law school, typified by English law.
- Full Text:
- Date Issued: 2006