Fluorescence behavior of nanoconjugates of graphene quantum dots and zinc phthalocyanines
- Achadu, Ojodomo John, Uddin, Imran, Nyokong, Tebello
- Authors: Achadu, Ojodomo John , Uddin, Imran , Nyokong, Tebello
- Date: 2016
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/188777 , vital:44784 , xlink:href="https://doi.org/10.1016/j.jphotochem.2015.11.006"
- Description: Graphene quantum dots (GQDs) and zinc phthalocyanines interactions in different modes (covalent and non-covalent) are reported in this study. GQDs were covalently attached to the following complexes: zinc tetraamino phthalocyanine (ZnTAPc) via amide coupling, zinc tetracarboxyphenoxy Pc (ZnTCPPc) (π–π interaction) and cationic zinc tetrapyridiloxy Pc (ZnTmPyPc) (ionic interaction). GQDs fluorescence was quenched in the presence of the ZnPc derivatives. The nanoensembles of GQDs–ZnPcs showed stimulated emissions of the ZnPcs. The suggested quenching mechanism is through Förster resonance energy transfer (FRET). These novel nanoensembles hold promise for various optical and luminescence based applications.
- Full Text:
- Date Issued: 2016
- Authors: Achadu, Ojodomo John , Uddin, Imran , Nyokong, Tebello
- Date: 2016
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/188777 , vital:44784 , xlink:href="https://doi.org/10.1016/j.jphotochem.2015.11.006"
- Description: Graphene quantum dots (GQDs) and zinc phthalocyanines interactions in different modes (covalent and non-covalent) are reported in this study. GQDs were covalently attached to the following complexes: zinc tetraamino phthalocyanine (ZnTAPc) via amide coupling, zinc tetracarboxyphenoxy Pc (ZnTCPPc) (π–π interaction) and cationic zinc tetrapyridiloxy Pc (ZnTmPyPc) (ionic interaction). GQDs fluorescence was quenched in the presence of the ZnPc derivatives. The nanoensembles of GQDs–ZnPcs showed stimulated emissions of the ZnPcs. The suggested quenching mechanism is through Förster resonance energy transfer (FRET). These novel nanoensembles hold promise for various optical and luminescence based applications.
- Full Text:
- Date Issued: 2016
Fluorescence properties of alloyed ZnSeS quantum dots overcoated with ZnTe and ZnTe/ZnS shells
- Adegoke, Oluwasesan, Mashazi, Philani N, Nyokong, Tebello, Forbes, Patricia B C
- Authors: Adegoke, Oluwasesan , Mashazi, Philani N , Nyokong, Tebello , Forbes, Patricia B C
- Date: 2016
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/240754 , vital:50868 , xlink:href="https://doi.org/10.1016/j.optmat.2016.02.024"
- Description: Fluorescent alloyed ternary ZnSeS quantum dots (QDs) have been synthesized via the pyrolysis of organometallic precursors. The effects of passivation of ZnTe and ZnTe/ZnS shells on the optical properties of the ternary alloyed ZnSeS core have been studied. A ligand exchange reaction using L-cysteine as a capping ligand was used to obtain water-soluble nanocrystals. The nanocrystals were each characterized by UV/vis absorption and fluorescence spectroscopy, transmission electron microscopy, X-ray diffractometry (XRD) and X-ray photoelectron spectroscopy (XPS). The photoluminescence (PL) quantum yield (QY) of alloyed ZnSeS QDs was 14% and this value increased to 27% when ZnTe was overcoated around the surface but further coating with a ZnS shell decreased the PL QY slightly to 24%. This implies that ZnTe shell suppressed non-radiative recombination exciton states in the alloyed core while further layering with a ZnS shell offered no further improvement in suppressing the defect states. XPS analysis confirmed the presence of the first shell layering but showed a weakened intensity signal of S (2p) and Se (3d) for the ZnSeS/ZnTe/ZnS QDs. Our work demonstrates for the first time that shell passivation of alloyed Zn-based QDs can offer improved optical properties. We hope the optical information presented in this work will be useful in the selection of alloyed Zn-based QDs appropriate for the intended application.
- Full Text:
- Date Issued: 2016
- Authors: Adegoke, Oluwasesan , Mashazi, Philani N , Nyokong, Tebello , Forbes, Patricia B C
- Date: 2016
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/240754 , vital:50868 , xlink:href="https://doi.org/10.1016/j.optmat.2016.02.024"
- Description: Fluorescent alloyed ternary ZnSeS quantum dots (QDs) have been synthesized via the pyrolysis of organometallic precursors. The effects of passivation of ZnTe and ZnTe/ZnS shells on the optical properties of the ternary alloyed ZnSeS core have been studied. A ligand exchange reaction using L-cysteine as a capping ligand was used to obtain water-soluble nanocrystals. The nanocrystals were each characterized by UV/vis absorption and fluorescence spectroscopy, transmission electron microscopy, X-ray diffractometry (XRD) and X-ray photoelectron spectroscopy (XPS). The photoluminescence (PL) quantum yield (QY) of alloyed ZnSeS QDs was 14% and this value increased to 27% when ZnTe was overcoated around the surface but further coating with a ZnS shell decreased the PL QY slightly to 24%. This implies that ZnTe shell suppressed non-radiative recombination exciton states in the alloyed core while further layering with a ZnS shell offered no further improvement in suppressing the defect states. XPS analysis confirmed the presence of the first shell layering but showed a weakened intensity signal of S (2p) and Se (3d) for the ZnSeS/ZnTe/ZnS QDs. Our work demonstrates for the first time that shell passivation of alloyed Zn-based QDs can offer improved optical properties. We hope the optical information presented in this work will be useful in the selection of alloyed Zn-based QDs appropriate for the intended application.
- Full Text:
- Date Issued: 2016
Focus on 'the family'?: how South African family policy could fail us
- Morison, Tracy, Lynch, Ingrid, Macleod, Catriona I
- Authors: Morison, Tracy , Lynch, Ingrid , Macleod, Catriona I
- Date: 2016
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/446244 , vital:74484 , xlink:href="https://hsrc.ac.za/uploads/pageContent/7505/HSRC%20POLICY%20BRIEF%2011%20-%20MORISON%20Family%20policy_PRESS%20(2).pdf"
- Description: In the past decade South African policymakers have increasingly focused on families as sites of state intervention. To date, several family policies have been developed to support societal well-being and cohesion. The most recent policy document is the White Paper on Families in South Africa (DSD 2012), which aims to facilitate the mainstreaming of a family perspective into all government policy-making. Family policies are intended to provide support, enhance family members’ wellbeing, strengthen family relationships, and help families address social challenges, such as economic instability. Their ultimate aim is to ensure a safe and socially cohesive society (Robila 2014). A core concern, therefore, is with promoting ‘stable, healthy families’. This concern is valid in South Africa since many families experienced a profound lack of stability under apartheid and today instability is brought about by various socio-economic changes, especially the HIV and AIDS epidemic.
- Full Text:
- Date Issued: 2016
- Authors: Morison, Tracy , Lynch, Ingrid , Macleod, Catriona I
- Date: 2016
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/446244 , vital:74484 , xlink:href="https://hsrc.ac.za/uploads/pageContent/7505/HSRC%20POLICY%20BRIEF%2011%20-%20MORISON%20Family%20policy_PRESS%20(2).pdf"
- Description: In the past decade South African policymakers have increasingly focused on families as sites of state intervention. To date, several family policies have been developed to support societal well-being and cohesion. The most recent policy document is the White Paper on Families in South Africa (DSD 2012), which aims to facilitate the mainstreaming of a family perspective into all government policy-making. Family policies are intended to provide support, enhance family members’ wellbeing, strengthen family relationships, and help families address social challenges, such as economic instability. Their ultimate aim is to ensure a safe and socially cohesive society (Robila 2014). A core concern, therefore, is with promoting ‘stable, healthy families’. This concern is valid in South Africa since many families experienced a profound lack of stability under apartheid and today instability is brought about by various socio-economic changes, especially the HIV and AIDS epidemic.
- Full Text:
- Date Issued: 2016
Fundisa for Change teacher professional development programme
- Authors: Tshiningayamwe, Sirkka A
- Date: 2016
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/432999 , vital:72922 , xlink:href="https://eeasa.org.za/wp-content/uploads/2017/05/EEASA-Bullitin-vol-43.pdf"
- Description: Environment and sustainability content has been integrated into the South African curricula documents, including the past ones. This integration was followed by initiatives which aimed at supporting teachers to implement environmental knowledge and action in the curriculum. For example, the Learning for Sustainability project was piloted in Gauteng and Mpumalanga province between the year 1997 and 2000. The project followed a three pillar approach of integrating environmental education in the curriculum: teacher development, curriculum development and materials development. As part of the project, a spiral model approach to teacher professional development was introduced.
- Full Text:
- Date Issued: 2016
- Authors: Tshiningayamwe, Sirkka A
- Date: 2016
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/432999 , vital:72922 , xlink:href="https://eeasa.org.za/wp-content/uploads/2017/05/EEASA-Bullitin-vol-43.pdf"
- Description: Environment and sustainability content has been integrated into the South African curricula documents, including the past ones. This integration was followed by initiatives which aimed at supporting teachers to implement environmental knowledge and action in the curriculum. For example, the Learning for Sustainability project was piloted in Gauteng and Mpumalanga province between the year 1997 and 2000. The project followed a three pillar approach of integrating environmental education in the curriculum: teacher development, curriculum development and materials development. As part of the project, a spiral model approach to teacher professional development was introduced.
- Full Text:
- Date Issued: 2016
Graphene quantum dots functionalized with 4-amino-2, 2, 6, 6-tetramethylpiperidine-N-oxide as fluorescence “turn-on” nanosensors
- Achadu, Ojodomo J, Britton, Jonathan, Nyokong, Tebello
- Authors: Achadu, Ojodomo J , Britton, Jonathan , Nyokong, Tebello
- Date: 2016
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/239854 , vital:50773 , xlink:href="https://doi.org/10.1007/s10895-016-1916-y"
- Description: In this study, we report on the fabrication of simple and rapid graphene quantum dots (GQDs)-based fluorescence “turn-ON” nanoprobes for sensitive and selective detection of ascorbic acid (AA). Pristine GQDs and S and N co-doped-GQDs (SN-GQDs) were functionalized with 4-amino-2,2,6,6-tetramethylpiperidine-N-oxide (4-amino-TEMPO, a nitroxide free radical). The nitroxide free radicals efficiently quenched the fluorescence of the GQDs and upon interaction of the nanoconjugates with ascorbic acid, the quenched fluorescence was restored. The linear ranges recorded were 0.5–5.7 μM and 0.1–5.5 μM for GQDs-4-amino-TEMPO and SN-GQDs-4amino-TEMPO nanoprobes, respectively. Limits of detection were found to be 60 nM and 84 nM for SN-GQDS-4-amino-TEMPO and GQDs-4-amino-TEMPO for AA detection, respectively. This novel fluorescence “turn-ON” technique showed to be highly rapid and selective towards AA detection.
- Full Text:
- Date Issued: 2016
- Authors: Achadu, Ojodomo J , Britton, Jonathan , Nyokong, Tebello
- Date: 2016
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/239854 , vital:50773 , xlink:href="https://doi.org/10.1007/s10895-016-1916-y"
- Description: In this study, we report on the fabrication of simple and rapid graphene quantum dots (GQDs)-based fluorescence “turn-ON” nanoprobes for sensitive and selective detection of ascorbic acid (AA). Pristine GQDs and S and N co-doped-GQDs (SN-GQDs) were functionalized with 4-amino-2,2,6,6-tetramethylpiperidine-N-oxide (4-amino-TEMPO, a nitroxide free radical). The nitroxide free radicals efficiently quenched the fluorescence of the GQDs and upon interaction of the nanoconjugates with ascorbic acid, the quenched fluorescence was restored. The linear ranges recorded were 0.5–5.7 μM and 0.1–5.5 μM for GQDs-4-amino-TEMPO and SN-GQDs-4amino-TEMPO nanoprobes, respectively. Limits of detection were found to be 60 nM and 84 nM for SN-GQDS-4-amino-TEMPO and GQDs-4-amino-TEMPO for AA detection, respectively. This novel fluorescence “turn-ON” technique showed to be highly rapid and selective towards AA detection.
- Full Text:
- Date Issued: 2016
Heterogeneity in virulence relationships between Cryptophlebia leucotreta granulovirus isolates and geographically distinct host populations: Lessons from codling moth resistance to CpGV-M
- Opoku-Debrah, John K, Hill, Martin P, Knox, Caroline M, Moore, Sean D
- Authors: Opoku-Debrah, John K , Hill, Martin P , Knox, Caroline M , Moore, Sean D
- Date: 2016
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/417998 , vital:71500 , xlink:href="https://doi.org/10.1007/s10526-016-9728-1"
- Description: In South Africa, the baculovirus Cryptophlebia leucotreta granulovirus (CrleGV) is used to control the citrus pest Thaumatotibia leucotreta (Meyrick) (Lepidoptera: Tortricidae). However, the risk associated with continuous application of a single active ingredient is resistance. In order to manage resistance should it occur in field populations of T. leucotreta in South Africa, five new CrleGV genotypes from geographically distinct insect populations which were shown to exhibit some degree of phenotypic variation were recovered and genetically characterized. In droplet bioassays using seven CrleGV isolates against five T. leucotreta populations, some isolates were found to show higher virulence to some host populations than others. There were marked differences in the LD50 values of isolates and the number of occlusion bodies required per larva ranged between 0.79 and 3.12. The significance of these findings with respect to the application of CrleGV biopesticides and the management of resistance is discussed.
- Full Text:
- Date Issued: 2016
- Authors: Opoku-Debrah, John K , Hill, Martin P , Knox, Caroline M , Moore, Sean D
- Date: 2016
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/417998 , vital:71500 , xlink:href="https://doi.org/10.1007/s10526-016-9728-1"
- Description: In South Africa, the baculovirus Cryptophlebia leucotreta granulovirus (CrleGV) is used to control the citrus pest Thaumatotibia leucotreta (Meyrick) (Lepidoptera: Tortricidae). However, the risk associated with continuous application of a single active ingredient is resistance. In order to manage resistance should it occur in field populations of T. leucotreta in South Africa, five new CrleGV genotypes from geographically distinct insect populations which were shown to exhibit some degree of phenotypic variation were recovered and genetically characterized. In droplet bioassays using seven CrleGV isolates against five T. leucotreta populations, some isolates were found to show higher virulence to some host populations than others. There were marked differences in the LD50 values of isolates and the number of occlusion bodies required per larva ranged between 0.79 and 3.12. The significance of these findings with respect to the application of CrleGV biopesticides and the management of resistance is discussed.
- Full Text:
- Date Issued: 2016
How content analysis may complement and extend the insights of discourse analysis: An example of research on constructions of abortion in South African newspapers 1978–2005
- Feltham-King, Tracey, Macleod, Catriona I
- Authors: Feltham-King, Tracey , Macleod, Catriona I
- Date: 2016
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/446258 , vital:74485 , xlink:href="https://doi.org/10.1177/1609406915624575"
- Description: Although discourse analysis is a well-established qualitative research methodology, little attention has been paid to how discourse analysis may be enhanced through careful supplementation with the quantification allowed in content analysis. In this article, we report on a research study that involved the use of both Foucauldian discourse analysis (FDA) and directed content analysis based on social constructionist theory and our qualitative research findings. The research focused on the discourses deployed, and the ways in which women were discursively positioned, in relation to abortion in 300 newspaper articles, published in 25 national and regional South African newspapers over 28 years, from 1978 to 2005. While the FDA was able to illuminate the constitutive network of power relations constructing women as subjects of a particular kind, questions emerged that were beyond the scope of the FDA. These questions concerned understanding the relative weightings of various discourses and tracing historical changes in the deployment of these discourses. In this article, we show how the decision to combine FDA and content analysis affected our sampling methodology. Using specific examples, we illustrate the contribution of the FDA to the study. Then, we indicate how subject positioning formed the link between the FDA and the content analysis. Drawing on the same examples, we demonstrate how the content analysis supplemented the FDA through tracking changes over time and providing empirical evidence of the extent to which subject positionings were deployed.
- Full Text:
- Date Issued: 2016
- Authors: Feltham-King, Tracey , Macleod, Catriona I
- Date: 2016
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/446258 , vital:74485 , xlink:href="https://doi.org/10.1177/1609406915624575"
- Description: Although discourse analysis is a well-established qualitative research methodology, little attention has been paid to how discourse analysis may be enhanced through careful supplementation with the quantification allowed in content analysis. In this article, we report on a research study that involved the use of both Foucauldian discourse analysis (FDA) and directed content analysis based on social constructionist theory and our qualitative research findings. The research focused on the discourses deployed, and the ways in which women were discursively positioned, in relation to abortion in 300 newspaper articles, published in 25 national and regional South African newspapers over 28 years, from 1978 to 2005. While the FDA was able to illuminate the constitutive network of power relations constructing women as subjects of a particular kind, questions emerged that were beyond the scope of the FDA. These questions concerned understanding the relative weightings of various discourses and tracing historical changes in the deployment of these discourses. In this article, we show how the decision to combine FDA and content analysis affected our sampling methodology. Using specific examples, we illustrate the contribution of the FDA to the study. Then, we indicate how subject positioning formed the link between the FDA and the content analysis. Drawing on the same examples, we demonstrate how the content analysis supplemented the FDA through tracking changes over time and providing empirical evidence of the extent to which subject positionings were deployed.
- Full Text:
- Date Issued: 2016
Impacts of HIV/AIDS on food consumption and wild food use in rural South Africa
- Ncube, Keitometsi, Shackleton, Charlie M, Swallow, Brent M, Dassanayake, Wijaya
- Authors: Ncube, Keitometsi , Shackleton, Charlie M , Swallow, Brent M , Dassanayake, Wijaya
- Date: 2016
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/180412 , vital:43385 , xlink:href="https://doi.org/10.1007/s12571-016-0624-4"
- Description: HIV/AIDS can affect household food consumption in many ways, including through reductions in availability and quality of labour, reductions in earned income, and increased expenditure on medications. In rural South Africa, these negative effects can be buffered by social safety net programs provided by government and collection of wild foods. Despite some acknowledgement of the potential safety net role of wild foods, however, their contribution relative to other food sources in the context of HIV/AIDS remains underexplored. Here we report empirical findings from two rural communities in the Eastern Cape province of South Africa. Qualitative and quantitative methods were used to characterise food sources, intake and calories from 68 HIV/AIDS afflicted households and 87 non-afflicted households every quarter over 12 months. Results show that diets were moderately well-balanced though limited in variety, with cereal items contributing 52 % to total calorie intake. The bulk of food consumed by households was purchased, with supplementation from own production, collected wild vegetables and collected wild fruits. Up to 20 % of respondents from both HIV/ AIDS afflicted and non-afflicted households had insufficient daily caloric intake. Multivariate analyses show that, all else equal, individuals living in households afflicted by HIV/AIDS consumed fewer calories, had less diverse diets, and were more dependent on wild foods than those living in non-afflicted households. Given the detrimental effects of HIV/AIDS on income and home production, wild foods represent a free and readily available food source for vulnerable households.
- Full Text:
- Date Issued: 2016
- Authors: Ncube, Keitometsi , Shackleton, Charlie M , Swallow, Brent M , Dassanayake, Wijaya
- Date: 2016
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/180412 , vital:43385 , xlink:href="https://doi.org/10.1007/s12571-016-0624-4"
- Description: HIV/AIDS can affect household food consumption in many ways, including through reductions in availability and quality of labour, reductions in earned income, and increased expenditure on medications. In rural South Africa, these negative effects can be buffered by social safety net programs provided by government and collection of wild foods. Despite some acknowledgement of the potential safety net role of wild foods, however, their contribution relative to other food sources in the context of HIV/AIDS remains underexplored. Here we report empirical findings from two rural communities in the Eastern Cape province of South Africa. Qualitative and quantitative methods were used to characterise food sources, intake and calories from 68 HIV/AIDS afflicted households and 87 non-afflicted households every quarter over 12 months. Results show that diets were moderately well-balanced though limited in variety, with cereal items contributing 52 % to total calorie intake. The bulk of food consumed by households was purchased, with supplementation from own production, collected wild vegetables and collected wild fruits. Up to 20 % of respondents from both HIV/ AIDS afflicted and non-afflicted households had insufficient daily caloric intake. Multivariate analyses show that, all else equal, individuals living in households afflicted by HIV/AIDS consumed fewer calories, had less diverse diets, and were more dependent on wild foods than those living in non-afflicted households. Given the detrimental effects of HIV/AIDS on income and home production, wild foods represent a free and readily available food source for vulnerable households.
- Full Text:
- Date Issued: 2016
Improvement of nonlinear optical properties of phthalocyanine bearing diethyleneglycole chains
- Britton, Jonathan, Martynov, Alexander G, Oluwole, David O, Gorbunova, Yulia G, Tsivadze, Yulia G, Nyokong, Tebello
- Authors: Britton, Jonathan , Martynov, Alexander G , Oluwole, David O , Gorbunova, Yulia G , Tsivadze, Yulia G , Nyokong, Tebello
- Date: 2016
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/239812 , vital:50769 , xlink:href="https://doi.org/10.1142/S1088424616501042"
- Description: This paper reports the successful synthesis of the low symmetry phthalocyanines: metal-free 2,3-bis[2′-(2′′-hydroxyethoxy)ethoxy]-9,10,16,17,23,24-hexa-nn-butoxyphthalocyanine 1H22 and its zinc complex 1Zn along with their nonlinear optical (NLO) behavior in solution and in thin films. 1H NMR investigations evidenced of higher dissymmetry of electronic density in 1H22 in comparison with 1Zn. This dissymmetry is responsible for unusually higher values of Im[χ(3)χ(3)]/αα, βeffβeff, and γγ for 1H22in contrast to 1Zn, where the notable effect of heavy-metal enhancement of ISC was expected. Both compounds showed Im[χ(3)χ(3)]/αα values of the order of 10−11−11 in chloroform which are higher in comparison to the symmetrical octabutoxyphthalocyanine H2[(BuO)8Pc]. NLO properties of 1H22 were improved via its incorporation into polycarbonate polymeric matrix together with CdSe@CdS-TOPO quantum dots. In such composite the value of Im[χ(3)χ(3)]/αα was almost three times higher in comparison with 1H22 solution in chloroform. The obtained composites are expected to be perspective components of optical materials, capable of protection against strong light irradiation
- Full Text:
- Date Issued: 2016
- Authors: Britton, Jonathan , Martynov, Alexander G , Oluwole, David O , Gorbunova, Yulia G , Tsivadze, Yulia G , Nyokong, Tebello
- Date: 2016
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/239812 , vital:50769 , xlink:href="https://doi.org/10.1142/S1088424616501042"
- Description: This paper reports the successful synthesis of the low symmetry phthalocyanines: metal-free 2,3-bis[2′-(2′′-hydroxyethoxy)ethoxy]-9,10,16,17,23,24-hexa-nn-butoxyphthalocyanine 1H22 and its zinc complex 1Zn along with their nonlinear optical (NLO) behavior in solution and in thin films. 1H NMR investigations evidenced of higher dissymmetry of electronic density in 1H22 in comparison with 1Zn. This dissymmetry is responsible for unusually higher values of Im[χ(3)χ(3)]/αα, βeffβeff, and γγ for 1H22in contrast to 1Zn, where the notable effect of heavy-metal enhancement of ISC was expected. Both compounds showed Im[χ(3)χ(3)]/αα values of the order of 10−11−11 in chloroform which are higher in comparison to the symmetrical octabutoxyphthalocyanine H2[(BuO)8Pc]. NLO properties of 1H22 were improved via its incorporation into polycarbonate polymeric matrix together with CdSe@CdS-TOPO quantum dots. In such composite the value of Im[χ(3)χ(3)]/αα was almost three times higher in comparison with 1H22 solution in chloroform. The obtained composites are expected to be perspective components of optical materials, capable of protection against strong light irradiation
- Full Text:
- Date Issued: 2016
Incorporation of environmental issues in South Africa’s municipal Integrated Development Plans
- Ruwanza, Sheunesu, Shackleton, Charlie M
- Authors: Ruwanza, Sheunesu , Shackleton, Charlie M
- Date: 2016
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/180481 , vital:43393 , xlink:href="https://doi.org/10.1080/13504509.2015.1062161"
- Description: The transition to full democracy in South Africa in 1994 saw local government becoming the focal point for dealing with socio-economic development needs of communities. The Integrated Development Plan (IDP) has been used as the tool for guiding local development objectives, balanced against environmental demands within a sustainable development paradigm. Here we examine the extent to which this is being achieved through an analysis of IDPs from 35 different municipalities at three scales. We test the hypothesis that the metropolitan municipalities are better at mainstreaming environmental issues into their IDPs than local and district municipalities. Results indicate that mainstreaming environmental issues in IDPs is still low. The hypothesis that metropoles are better at mainstreaming environmental issues than district and local municipalities was not accepted since there were no significant differences between municipalities. There was low relative budget allocations and inclusion of vision and mission statements that mainstream environmental issues in all municipalities. For mainstreaming of environmental issues to be effective in IDPs, both proactive approaches and multi-faceted bottom-up and top-down approaches are suggested.
- Full Text:
- Date Issued: 2016
- Authors: Ruwanza, Sheunesu , Shackleton, Charlie M
- Date: 2016
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/180481 , vital:43393 , xlink:href="https://doi.org/10.1080/13504509.2015.1062161"
- Description: The transition to full democracy in South Africa in 1994 saw local government becoming the focal point for dealing with socio-economic development needs of communities. The Integrated Development Plan (IDP) has been used as the tool for guiding local development objectives, balanced against environmental demands within a sustainable development paradigm. Here we examine the extent to which this is being achieved through an analysis of IDPs from 35 different municipalities at three scales. We test the hypothesis that the metropolitan municipalities are better at mainstreaming environmental issues into their IDPs than local and district municipalities. Results indicate that mainstreaming environmental issues in IDPs is still low. The hypothesis that metropoles are better at mainstreaming environmental issues than district and local municipalities was not accepted since there were no significant differences between municipalities. There was low relative budget allocations and inclusion of vision and mission statements that mainstream environmental issues in all municipalities. For mainstreaming of environmental issues to be effective in IDPs, both proactive approaches and multi-faceted bottom-up and top-down approaches are suggested.
- Full Text:
- Date Issued: 2016
Interaction of graphene quantum dots with 4-acetamido-2, 2, 6, 6-tetramethylpiperidine-oxyl free radicals
- Achadu, Ojodomo John, Nyokong, Tebello
- Authors: Achadu, Ojodomo John , Nyokong, Tebello
- Date: 2016
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/189031 , vital:44810 , xlink:href="https://doi.org/10.1007/s10895-015-1712-0"
- Description: We report on the interaction of graphene quantum dots (GQDs) with 4-acetamido-2,2,6,6-tetramethylpiperidineoxyl (4-acetamido-TEMPO) free radicals. The GQDs were N and S, N doped. The fluorescence quantum yields were higher for the doped GQDs compared to the undoped. The interaction is assessed by spectrofluorimetric, steady state/time resolved fluorescence and electron paramagnetic resonance (EPR) techniques. Fluorescence quenching was observed upon the addition of 4-acetamido-TEMPO to the GQDs. Photoinduced electron transfer (PET) mechanism was suggested as the plausible mechanism involved in the fluorescence quenching in which 4-acetamido-TEMPO acted as the electron acceptor.
- Full Text:
- Date Issued: 2016
- Authors: Achadu, Ojodomo John , Nyokong, Tebello
- Date: 2016
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/189031 , vital:44810 , xlink:href="https://doi.org/10.1007/s10895-015-1712-0"
- Description: We report on the interaction of graphene quantum dots (GQDs) with 4-acetamido-2,2,6,6-tetramethylpiperidineoxyl (4-acetamido-TEMPO) free radicals. The GQDs were N and S, N doped. The fluorescence quantum yields were higher for the doped GQDs compared to the undoped. The interaction is assessed by spectrofluorimetric, steady state/time resolved fluorescence and electron paramagnetic resonance (EPR) techniques. Fluorescence quenching was observed upon the addition of 4-acetamido-TEMPO to the GQDs. Photoinduced electron transfer (PET) mechanism was suggested as the plausible mechanism involved in the fluorescence quenching in which 4-acetamido-TEMPO acted as the electron acceptor.
- Full Text:
- Date Issued: 2016
Introducing State of the Discipline Papers
- Macleod, Catriona I, Capdevila, Rose, Marecek, Jeanne
- Authors: Macleod, Catriona I , Capdevila, Rose , Marecek, Jeanne
- Date: 2016
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/446272 , vital:74486 , xlink:href="https://doi.org/10.1177/0959353516649724"
- Description: The editors of Feminism and Psychology are delighted to introduce the first of our State of the Discipline papers. Twenty-five years have passed since the establishment of FandP. Significant work in feminist psychology and in feminisms relevant to psychology has been published both in this jour-nal and in others since (and before) the establishment of FandP. The range of topics that feminists in psychology consider has expanded and the reach of feminist studies has broadened. In light of the dynamic growth of the field, we believe that the time is ripe to establish what we have termed ‘State of the Discipline’ papers. We envision this series as a collection of occasional papers pertaining to particular topics or issues. What, we ask, is the current state of a specific topic within feminisms and psychologies? The State of the Discipline papers, written by scholars with a long-standing engagement with the topic, are neither empirical articles nor literature re-views. Instead, the papers are intended to apprise readers of the current state of knowledge about the topic, drawing on the literatures of both psy-chology and feminist studies. The articles: summarise key developments; point out areas of conceptual and methodological debate among feminist scholars; open up the topic to further scrutiny and new ways of understand-ing; and promote nuanced work in the field.
- Full Text:
- Date Issued: 2016
- Authors: Macleod, Catriona I , Capdevila, Rose , Marecek, Jeanne
- Date: 2016
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/446272 , vital:74486 , xlink:href="https://doi.org/10.1177/0959353516649724"
- Description: The editors of Feminism and Psychology are delighted to introduce the first of our State of the Discipline papers. Twenty-five years have passed since the establishment of FandP. Significant work in feminist psychology and in feminisms relevant to psychology has been published both in this jour-nal and in others since (and before) the establishment of FandP. The range of topics that feminists in psychology consider has expanded and the reach of feminist studies has broadened. In light of the dynamic growth of the field, we believe that the time is ripe to establish what we have termed ‘State of the Discipline’ papers. We envision this series as a collection of occasional papers pertaining to particular topics or issues. What, we ask, is the current state of a specific topic within feminisms and psychologies? The State of the Discipline papers, written by scholars with a long-standing engagement with the topic, are neither empirical articles nor literature re-views. Instead, the papers are intended to apprise readers of the current state of knowledge about the topic, drawing on the literatures of both psy-chology and feminist studies. The articles: summarise key developments; point out areas of conceptual and methodological debate among feminist scholars; open up the topic to further scrutiny and new ways of understand-ing; and promote nuanced work in the field.
- Full Text:
- Date Issued: 2016
Investigating the role of the South African Schools Choral Eisteddfod in introducing learners to music career
- Authors: Sibene, Vuyelwa
- Date: 2016
- Subjects: Choral music -- South Africa , Choral singing -- Instruction and study -- South Africa
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10353/26382 , vital:65298
- Description: This research investigates the role of South African Schools Choral Eisteddfod (SASCE) in introducing learners in high schools to music career. It attempts to identify learners in grade 12 who want to study music at university and students who were involved in SASCE and are now in university. These learners and students have limited music background and are/were involved in the South African Schools Choral Eisteddfod (SASCE) program. Within the study, I felt to also include a graduated music student to validate the study. The study proceeds with the investigation by exploring numerous areas such as SASCE as a music program, music education, music careers, national curriculum, music literacy etc. Also, I write about the background to the study in which I share my motivation and experiences about the SASCE programme and how it influenced me and other former SASCE participants’ decisions about musical careers. Data collection is executed through the involvement of the sampled learner and students through participating in semi-structured interview, document analysis and personal observations. Four interviews which were in qualitative method were conducted with 4 participants, one interview each participant was in a semi-structure form. Interviews were aimed in recognizing the current status of the learner/students in music literacy and are they coping in their respected places of study. The data is analyzed using a qualitative analyses technique. Further, the study outlines problems and one research question of the investigation, 'To which extent do University music students with limited music background succeed or fail to obtain their music degrees?’. , Thesis (BMUS) -- Faculty of Humanities, 2016
- Full Text:
- Date Issued: 2016
- Authors: Sibene, Vuyelwa
- Date: 2016
- Subjects: Choral music -- South Africa , Choral singing -- Instruction and study -- South Africa
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10353/26382 , vital:65298
- Description: This research investigates the role of South African Schools Choral Eisteddfod (SASCE) in introducing learners in high schools to music career. It attempts to identify learners in grade 12 who want to study music at university and students who were involved in SASCE and are now in university. These learners and students have limited music background and are/were involved in the South African Schools Choral Eisteddfod (SASCE) program. Within the study, I felt to also include a graduated music student to validate the study. The study proceeds with the investigation by exploring numerous areas such as SASCE as a music program, music education, music careers, national curriculum, music literacy etc. Also, I write about the background to the study in which I share my motivation and experiences about the SASCE programme and how it influenced me and other former SASCE participants’ decisions about musical careers. Data collection is executed through the involvement of the sampled learner and students through participating in semi-structured interview, document analysis and personal observations. Four interviews which were in qualitative method were conducted with 4 participants, one interview each participant was in a semi-structure form. Interviews were aimed in recognizing the current status of the learner/students in music literacy and are they coping in their respected places of study. The data is analyzed using a qualitative analyses technique. Further, the study outlines problems and one research question of the investigation, 'To which extent do University music students with limited music background succeed or fail to obtain their music degrees?’. , Thesis (BMUS) -- Faculty of Humanities, 2016
- Full Text:
- Date Issued: 2016
Islamic compliant short term insurance: an exploratory study to develop an Islamic compliant insurance model within a South African context
- Authors: Jeeva, Shakir
- Date: 2016
- Subjects: Uncatalogued
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10962/193633 , vital:45375
- Description: In a world where there is ever increasing risks to be mitigated, either by choice or due to the law of the country, an insurance instrument is the most popular risk mitigation tool. However, from an Islamic perspective, Muslims have certain parameters to adhere to due to the laws and boundaries as set out in the Quraan, as well as the teachings of the final prophet, Prophet Muhammed (Peace Be Upon Him). This has relevance in this context as, according to Islam, the conventional insurance models are in contravention of certain Islamic laws as they contain elements which are not acceptable in the Muslim faith. Therefore, the Islamic insurance models, or Takaful models, have removed the impermissible elements of usury, speculation, and uncertainty, which are all contained in the current conventional insurance models. By removing these impermissible elements from the insurance model, the Takaful model is acceptable for Muslims to use as a risk mitigation tool. The primary aim of the study sought to propose a short term Islamic compliant insurance model within a South African framework. The secondary aims were to ascertain the Islamic requirements for an Islamic insurance model, how these requirements fit into an insurance model, to then compare and contrast the differences between conventional insurance and Islamic insurance and, lastly, to explore awareness and attitudes towards Islamic insurance. Therefore, from the above, a proposed short term Islamic insurance model was developed within a South African context which conforms to the laws and boundaries of Islam, making this insurance model permissible to use as a Takaful tool. Additionally, semi structured interviews were conducted with certain research participants, using purposive sampling, to examine the attitudes and knowledge of the Muslim community towards the Takaful model within a South African context. It was concluded that while the majority of the research participants understand the Takaful model and the significance of this, they have chosen to use the conventional insurance offerings due to the fact that they were unaware of other Takaful alternatives, or due to the fact that the Takaful alternative was out-priced when compared to the conventional insurance offerings. It was therefore concluded that while there is a need for Takaful offerings within South Africa, this must be done in conjunction with additional marketing, education and competitive pricing for potential clients to consider this as an insurance option. , Thesis (MCom) -- Faculty of Commerce, Accounting, 2016
- Full Text:
- Date Issued: 2016
- Authors: Jeeva, Shakir
- Date: 2016
- Subjects: Uncatalogued
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10962/193633 , vital:45375
- Description: In a world where there is ever increasing risks to be mitigated, either by choice or due to the law of the country, an insurance instrument is the most popular risk mitigation tool. However, from an Islamic perspective, Muslims have certain parameters to adhere to due to the laws and boundaries as set out in the Quraan, as well as the teachings of the final prophet, Prophet Muhammed (Peace Be Upon Him). This has relevance in this context as, according to Islam, the conventional insurance models are in contravention of certain Islamic laws as they contain elements which are not acceptable in the Muslim faith. Therefore, the Islamic insurance models, or Takaful models, have removed the impermissible elements of usury, speculation, and uncertainty, which are all contained in the current conventional insurance models. By removing these impermissible elements from the insurance model, the Takaful model is acceptable for Muslims to use as a risk mitigation tool. The primary aim of the study sought to propose a short term Islamic compliant insurance model within a South African framework. The secondary aims were to ascertain the Islamic requirements for an Islamic insurance model, how these requirements fit into an insurance model, to then compare and contrast the differences between conventional insurance and Islamic insurance and, lastly, to explore awareness and attitudes towards Islamic insurance. Therefore, from the above, a proposed short term Islamic insurance model was developed within a South African context which conforms to the laws and boundaries of Islam, making this insurance model permissible to use as a Takaful tool. Additionally, semi structured interviews were conducted with certain research participants, using purposive sampling, to examine the attitudes and knowledge of the Muslim community towards the Takaful model within a South African context. It was concluded that while the majority of the research participants understand the Takaful model and the significance of this, they have chosen to use the conventional insurance offerings due to the fact that they were unaware of other Takaful alternatives, or due to the fact that the Takaful alternative was out-priced when compared to the conventional insurance offerings. It was therefore concluded that while there is a need for Takaful offerings within South Africa, this must be done in conjunction with additional marketing, education and competitive pricing for potential clients to consider this as an insurance option. , Thesis (MCom) -- Faculty of Commerce, Accounting, 2016
- Full Text:
- Date Issued: 2016
Knowledge, perceptions and willingness to control designated invasive tree species in urban household gardens in South Africa
- Shackleton, Charlie M, Shackleton, Ross T
- Authors: Shackleton, Charlie M , Shackleton, Ross T
- Date: 2016
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/180445 , vital:43389 , xlink:href="https://doi.org/10.1007/s10530-016-1104-7"
- Description: Many biological invasions result in negative impacts on the environment and human livelihoods, but simultaneously some also provide benefits that are valued differently by various stakeholders. To inform policy and management of invasive species it is important to assess landowners’ and broader society’s knowledge and perceptions of invasive species, something which is lacking in many contexts, especially in urban settings. In this study we interviewed 153 householders living in a medium-sized South African town who had declared invasive alien trees in their gardens. Less than half of the respondents could identify the invasive tree on their property and only one-third knew that it was an invasive alien species. There was a positive association between income and education levels with exposure to media about invasive alien species and respondents’ ability to identify the species and name any other invasive alien tree species. Knowledge levels were unequal across species. Amongst those who knew the tree was an invasive alien species, reasons why they retained it in their gardens included that it would be costly or too much effort to remove, they liked the tree, that it was not causing any harm and that the property was rented and so its removal was not their responsibility. However, the majority of people (83 %) were willing to have it removed from their garden if done for free by appropriate agencies, which is promising for compliance with new regulations on invasive species implemented at the end of 2014 in South Africa. The results also highlight the need for targeted and appropriate education and awareness programs amongst urban householders on invasive alien species, relevant legislation and their obligations.
- Full Text:
- Date Issued: 2016
- Authors: Shackleton, Charlie M , Shackleton, Ross T
- Date: 2016
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/180445 , vital:43389 , xlink:href="https://doi.org/10.1007/s10530-016-1104-7"
- Description: Many biological invasions result in negative impacts on the environment and human livelihoods, but simultaneously some also provide benefits that are valued differently by various stakeholders. To inform policy and management of invasive species it is important to assess landowners’ and broader society’s knowledge and perceptions of invasive species, something which is lacking in many contexts, especially in urban settings. In this study we interviewed 153 householders living in a medium-sized South African town who had declared invasive alien trees in their gardens. Less than half of the respondents could identify the invasive tree on their property and only one-third knew that it was an invasive alien species. There was a positive association between income and education levels with exposure to media about invasive alien species and respondents’ ability to identify the species and name any other invasive alien tree species. Knowledge levels were unequal across species. Amongst those who knew the tree was an invasive alien species, reasons why they retained it in their gardens included that it would be costly or too much effort to remove, they liked the tree, that it was not causing any harm and that the property was rented and so its removal was not their responsibility. However, the majority of people (83 %) were willing to have it removed from their garden if done for free by appropriate agencies, which is promising for compliance with new regulations on invasive species implemented at the end of 2014 in South Africa. The results also highlight the need for targeted and appropriate education and awareness programs amongst urban householders on invasive alien species, relevant legislation and their obligations.
- Full Text:
- Date Issued: 2016
MCD spectroscopy and TD-DFT calculations of magnesium tetra-(15-crown-5-oxanthreno)-phthalocyanine
- Mack, John, Mkhize, Scebi, Safonoya, Evgeniya A, Gorbunova, Yulia G, Tsivadze, Aslan Yu, Nyokong, Tebello
- Authors: Mack, John , Mkhize, Scebi , Safonoya, Evgeniya A , Gorbunova, Yulia G , Tsivadze, Aslan Yu , Nyokong, Tebello
- Date: 2016
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/240743 , vital:50867 , xlink:href="https://doi.org/10.1142/S1088424616500322"
- Description: An analysis of the MCD spectroscopy and TD-DFT calculations of magnesium tetra-(15-crown-5-oxanthreno)-phthalocyanine is reported. This study provides a reassessment of an earlier study on the nature of the bands in UV-visible absorption spectra of magnesium and zinc tetra-(15-crown-5-oxanthreno)-phthalocyanine that was based on an analysis of TD-DFT calculations for a series of model complexes with the B3LYP functional. A detailed analysis of MCD spectral data and TD-DFT calculations with the CAM-B3LYP functional for the complete Mg(II) complex provides an additional insight into the optical properties and electronic structures of tetra-(15-crown-5-oxanthreno)-phthalocyanines. Thus, the bands in the Q-band region are reassigned as being due exclusively to the Q transition of Gouterman’s 4-orbital model, since intense pseudo-A1𝒜1 terms are observed in the MCD spectrum in a spectral region that had previously been assigned as charge transfer bands.
- Full Text:
- Date Issued: 2016
- Authors: Mack, John , Mkhize, Scebi , Safonoya, Evgeniya A , Gorbunova, Yulia G , Tsivadze, Aslan Yu , Nyokong, Tebello
- Date: 2016
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/240743 , vital:50867 , xlink:href="https://doi.org/10.1142/S1088424616500322"
- Description: An analysis of the MCD spectroscopy and TD-DFT calculations of magnesium tetra-(15-crown-5-oxanthreno)-phthalocyanine is reported. This study provides a reassessment of an earlier study on the nature of the bands in UV-visible absorption spectra of magnesium and zinc tetra-(15-crown-5-oxanthreno)-phthalocyanine that was based on an analysis of TD-DFT calculations for a series of model complexes with the B3LYP functional. A detailed analysis of MCD spectral data and TD-DFT calculations with the CAM-B3LYP functional for the complete Mg(II) complex provides an additional insight into the optical properties and electronic structures of tetra-(15-crown-5-oxanthreno)-phthalocyanines. Thus, the bands in the Q-band region are reassigned as being due exclusively to the Q transition of Gouterman’s 4-orbital model, since intense pseudo-A1𝒜1 terms are observed in the MCD spectrum in a spectral region that had previously been assigned as charge transfer bands.
- Full Text:
- Date Issued: 2016
Molecular identification of Azolla invasions in Africa: The Azolla specialist, Stenopelmus rufinasus proves to be an excellent taxonomist
- Madeira, P T, Dray, F Allen, Coetzee, Julie A, Paterson, Iain D, Tipping, Philip W
- Authors: Madeira, P T , Dray, F Allen , Coetzee, Julie A , Paterson, Iain D , Tipping, Philip W
- Date: 2016
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/424765 , vital:72182 , xlink:href="https://doi.org/10.1016/j.sajb.2016.03.007"
- Description: Biological control of Azolla filiculoides in South Africa with the Azolla specialist Stenopelmus rufinasus has been highly successful. However, field surveys showed that the agent utilized another Azolla species, thought to be the native Azolla pinnata subsp. africana, which contradicted host specificity trials. It is notoriously difficult to determine Azolla species based on morphology so genetic analyses were required to confirm the identity of the Azolla used by the agent. Extensive sampling was conducted and samples were sequenced at the trnL-trnF and trnG-trnR chloroplastic regions and the nuclear ITS1 region. Current literature reported A. filiculoides as the only Section Azolla species in southern Africa but 24 samples were identified as Azolla cristata, an introduced species within Section Azolla that was not used during host specificity trials. A. pinnata subsp. africana was only located at one site in southern Africa, while the alien A. pinnata subsp. asiatica was located at three. What was thought to be A. pinnata subsp. africana was in fact A. cristata, a closer relative of A. filiculoides and a suitable host according to specificity trials. This study confirms that S. rufinasus is a proficient Azolla taxonomist but also supports the use of molecular techniques for resolving taxonomic conundrums.
- Full Text:
- Date Issued: 2016
- Authors: Madeira, P T , Dray, F Allen , Coetzee, Julie A , Paterson, Iain D , Tipping, Philip W
- Date: 2016
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/424765 , vital:72182 , xlink:href="https://doi.org/10.1016/j.sajb.2016.03.007"
- Description: Biological control of Azolla filiculoides in South Africa with the Azolla specialist Stenopelmus rufinasus has been highly successful. However, field surveys showed that the agent utilized another Azolla species, thought to be the native Azolla pinnata subsp. africana, which contradicted host specificity trials. It is notoriously difficult to determine Azolla species based on morphology so genetic analyses were required to confirm the identity of the Azolla used by the agent. Extensive sampling was conducted and samples were sequenced at the trnL-trnF and trnG-trnR chloroplastic regions and the nuclear ITS1 region. Current literature reported A. filiculoides as the only Section Azolla species in southern Africa but 24 samples were identified as Azolla cristata, an introduced species within Section Azolla that was not used during host specificity trials. A. pinnata subsp. africana was only located at one site in southern Africa, while the alien A. pinnata subsp. asiatica was located at three. What was thought to be A. pinnata subsp. africana was in fact A. cristata, a closer relative of A. filiculoides and a suitable host according to specificity trials. This study confirms that S. rufinasus is a proficient Azolla taxonomist but also supports the use of molecular techniques for resolving taxonomic conundrums.
- Full Text:
- Date Issued: 2016
Morphological variations in southern African populations of Myriophyllum spicatum: Phenotypic plasticity or local adaptation?
- Weyl, Philip S R, Coetzee, Julie A
- Authors: Weyl, Philip S R , Coetzee, Julie A
- Date: 2016
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/424789 , vital:72184 , xlink:href="https://doi.org/10.1016/j.sajb.2015.07.01"
- Description: Variability in aquatic plant morphology is usually driven by phenotypic plasticity and local adaptations to environmental conditions experienced. This study aimed to elucidate which of these drivers is responsible for the morphological variation exhibited by three populations of Myriophyllum spicatum L. (Haloragaceae), a submerged aquatic plant whose status as native or exotic within southern Africa is uncertain. Individuals from three populations on the Vaal River (Northern Cape), Klipplaat River (Eastern Cape) and Lake Sibaya (KwaZulu-Natal) were grown under two nutrient treatments (high: 30 mg N/kg sediment and low: sediment only), while all other variables were kept the same. Morphological characteristics were measured at the start of the experiment to obtain a baseline morphology, and again eight weeks later. By the end of the experiment, the individuals from each population had responded to the different growing conditions. In most cases, the individuals from each population were significantly larger under the high nutrient treatment (Stem diameter: F(5,86) = 18.435, P is less than 0.001, Internode length: F(5,86) = 5.0747, P is less than 0.001, Leaf length: F(5,86) = 19.692, P is less than 0.001). Despite these differences in nutrient treatments, the growth pattern of each population remained true to the original starting point indicated by the lack of overlap between populations in the PCA groupings. This suggests that local adaptations are responsible for the differences in morphology between populations of M. spicatum, but shows that phenotypic plasticity does play a role as evidenced by individual responses to the different nutrient conditions. The development of these local adaptations within southern Africa suggests that the populations have had a long evolutionary history in the region and are relatively isolated with little reproductive mixing.
- Full Text:
- Date Issued: 2016
- Authors: Weyl, Philip S R , Coetzee, Julie A
- Date: 2016
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/424789 , vital:72184 , xlink:href="https://doi.org/10.1016/j.sajb.2015.07.01"
- Description: Variability in aquatic plant morphology is usually driven by phenotypic plasticity and local adaptations to environmental conditions experienced. This study aimed to elucidate which of these drivers is responsible for the morphological variation exhibited by three populations of Myriophyllum spicatum L. (Haloragaceae), a submerged aquatic plant whose status as native or exotic within southern Africa is uncertain. Individuals from three populations on the Vaal River (Northern Cape), Klipplaat River (Eastern Cape) and Lake Sibaya (KwaZulu-Natal) were grown under two nutrient treatments (high: 30 mg N/kg sediment and low: sediment only), while all other variables were kept the same. Morphological characteristics were measured at the start of the experiment to obtain a baseline morphology, and again eight weeks later. By the end of the experiment, the individuals from each population had responded to the different growing conditions. In most cases, the individuals from each population were significantly larger under the high nutrient treatment (Stem diameter: F(5,86) = 18.435, P is less than 0.001, Internode length: F(5,86) = 5.0747, P is less than 0.001, Leaf length: F(5,86) = 19.692, P is less than 0.001). Despite these differences in nutrient treatments, the growth pattern of each population remained true to the original starting point indicated by the lack of overlap between populations in the PCA groupings. This suggests that local adaptations are responsible for the differences in morphology between populations of M. spicatum, but shows that phenotypic plasticity does play a role as evidenced by individual responses to the different nutrient conditions. The development of these local adaptations within southern Africa suggests that the populations have had a long evolutionary history in the region and are relatively isolated with little reproductive mixing.
- Full Text:
- Date Issued: 2016
Natural resource use, incomes, and poverty along the rural–urban continuum of two medium-sized, South African towns
- Ward, Catherine D, Shackleton, Charlie M
- Authors: Ward, Catherine D , Shackleton, Charlie M
- Date: 2016
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/180790 , vital:43646 , xlink:href="https://doi.org/10.1016/j.worlddev.2015.10.025"
- Description: Urbanization is a significant driver of global change, reshaping livelihoods, productive activities, and incomes. Yet, many elements of what are typically regarded as rural activities can be found in urban places and vice versa. We report on the incomes from land- and cash-based activities along the rural–urban gradient of two South African towns. Although the dominant income strategies varied, all households had more than one income source. Use of wild resources and agriculture were common in urban settings, although variable between and within towns. Poverty levels would be 5–10% higher in the absence of natural resource-based incomes.
- Full Text:
- Date Issued: 2016
- Authors: Ward, Catherine D , Shackleton, Charlie M
- Date: 2016
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/180790 , vital:43646 , xlink:href="https://doi.org/10.1016/j.worlddev.2015.10.025"
- Description: Urbanization is a significant driver of global change, reshaping livelihoods, productive activities, and incomes. Yet, many elements of what are typically regarded as rural activities can be found in urban places and vice versa. We report on the incomes from land- and cash-based activities along the rural–urban gradient of two South African towns. Although the dominant income strategies varied, all households had more than one income source. Use of wild resources and agriculture were common in urban settings, although variable between and within towns. Poverty levels would be 5–10% higher in the absence of natural resource-based incomes.
- Full Text:
- Date Issued: 2016
Nitrogen fertilisation improves growth of Chromolaena odorata (Asteraceae) and the performance of the biological control agent, Pareuchaetes insulata (Erebidae)
- Uyi, Osariyekemwen O, Zacharariades, Costas, Hill, Martin P
- Authors: Uyi, Osariyekemwen O , Zacharariades, Costas , Hill, Martin P
- Date: 2016
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/416880 , vital:71393 , xlink:href="https://doi.org/10.1080/09583157.2015.1118615"
- Description: Recent studies have demonstrated, through their contrasting results, that relationships between nitrogen levels in host plants and phytophagous insect performance are not simple. This study examined the effect of varying fertilisation regimes on the invasive alien plant, Chromolaena odorata (L.) (Asteraceae) and the response of a specialist folivore (a biological control agent), Pareuchaetes insulata (Walker) (Lepidoptera: Erebidae). C. odorata plants were treated with 3 different levels of fertilisation and plant characteristics were measured within 2–3 months of fertiliser application. Leaves from each of the three treatments were fed to newly hatched larvae until pupation in order to determine the effect of nitrogen fertilisation on herbivore performance metrics such as survival, development time, fecundity and longevity. High and medium fertilisation significantly increased foliar nitrogen concentrations, basal stem diameter, leaf length, shoot height and above-ground biomass of C. odorata plants relative to low fertilisation. When individuals of P. insulata were fed on leaves from medium- or high-fertilisation treatments, they developed faster, grew to a larger size (by 8%) and achieved higher fecundity (19–22%) than leaves from the low-fertilisation treatment. The results suggest that in mass-rearing, increased production of this biological control agent will occur in high- or medium-fertilised plants.
- Full Text:
- Date Issued: 2016
- Authors: Uyi, Osariyekemwen O , Zacharariades, Costas , Hill, Martin P
- Date: 2016
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/416880 , vital:71393 , xlink:href="https://doi.org/10.1080/09583157.2015.1118615"
- Description: Recent studies have demonstrated, through their contrasting results, that relationships between nitrogen levels in host plants and phytophagous insect performance are not simple. This study examined the effect of varying fertilisation regimes on the invasive alien plant, Chromolaena odorata (L.) (Asteraceae) and the response of a specialist folivore (a biological control agent), Pareuchaetes insulata (Walker) (Lepidoptera: Erebidae). C. odorata plants were treated with 3 different levels of fertilisation and plant characteristics were measured within 2–3 months of fertiliser application. Leaves from each of the three treatments were fed to newly hatched larvae until pupation in order to determine the effect of nitrogen fertilisation on herbivore performance metrics such as survival, development time, fecundity and longevity. High and medium fertilisation significantly increased foliar nitrogen concentrations, basal stem diameter, leaf length, shoot height and above-ground biomass of C. odorata plants relative to low fertilisation. When individuals of P. insulata were fed on leaves from medium- or high-fertilisation treatments, they developed faster, grew to a larger size (by 8%) and achieved higher fecundity (19–22%) than leaves from the low-fertilisation treatment. The results suggest that in mass-rearing, increased production of this biological control agent will occur in high- or medium-fertilised plants.
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- Date Issued: 2016