Ni(II) and Pb(II) dithiocarbamate complexes as precursors for the synthesis of HDA-capped NiS and PbS nanoparticles
- Authors: Chintso, Thobani
- Date: 2015
- Language: English
- Type: Thesis , Masters , MSc (Chemistry)
- Identifier: vital:11349 , http://hdl.handle.net/10353/d1020201
- Description: Ni(II) and Pb(II) dithiocarbamate complexes were synthesized and characterized by elemental analysis, UV-Vis, FTIR and TGA and some of the Ni(II) complexes and one Pb(II) were further analyzed by 1H-NMR and 13C-NMR spectroscopy. Generally all the dithiocarbamate ligands are soluble in water while the complexes were soluble mostly in solvents such as chloroform, toluene, DMSO and DCM. Based on the elemental analysis, the dithiocarbamate complexes are formulated as four coordinate (tetrahedral or square planar) compounds. However, the FTIR showed that each of the dithiocarbamate ligands acted as bidentate ligand through two sulfur atoms. The TGA of the most complexes showed one major decomposition step to give respective metal sulfide above 200 oC. In this research project, dithiocarbamate complexes were used as single source precursor for the synthesis of metal sulfide nanoparticles. We studied the optical and structural properties of metal sulfide nanoparticles using UV-Vis, photoluminescence (PL), powder X-ray diffraction (XRD), energy dispersive X-ray (EDX), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The absorption spectra of the metal sulfide nanoparticles are blue shifted in respect to bulk material and they also showed broad emission. The XRD of the NiS nanoparticles were indexed to the cubic and rhombohedral phase, with crystallite sizes of 15 - 18 nm. The XRD of PbS nanoparticles were indexed to the face centered cubic and cubic rock salts, with the crystallite sizes 12 - 18 nm. The TEM images of the metal sulfide nanoparticles showed particles with spherical and rectangular shapes with crystallite sizes 4 - 35 nm.
- Full Text:
- Date Issued: 2015
- Authors: Chintso, Thobani
- Date: 2015
- Language: English
- Type: Thesis , Masters , MSc (Chemistry)
- Identifier: vital:11349 , http://hdl.handle.net/10353/d1020201
- Description: Ni(II) and Pb(II) dithiocarbamate complexes were synthesized and characterized by elemental analysis, UV-Vis, FTIR and TGA and some of the Ni(II) complexes and one Pb(II) were further analyzed by 1H-NMR and 13C-NMR spectroscopy. Generally all the dithiocarbamate ligands are soluble in water while the complexes were soluble mostly in solvents such as chloroform, toluene, DMSO and DCM. Based on the elemental analysis, the dithiocarbamate complexes are formulated as four coordinate (tetrahedral or square planar) compounds. However, the FTIR showed that each of the dithiocarbamate ligands acted as bidentate ligand through two sulfur atoms. The TGA of the most complexes showed one major decomposition step to give respective metal sulfide above 200 oC. In this research project, dithiocarbamate complexes were used as single source precursor for the synthesis of metal sulfide nanoparticles. We studied the optical and structural properties of metal sulfide nanoparticles using UV-Vis, photoluminescence (PL), powder X-ray diffraction (XRD), energy dispersive X-ray (EDX), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The absorption spectra of the metal sulfide nanoparticles are blue shifted in respect to bulk material and they also showed broad emission. The XRD of the NiS nanoparticles were indexed to the cubic and rhombohedral phase, with crystallite sizes of 15 - 18 nm. The XRD of PbS nanoparticles were indexed to the face centered cubic and cubic rock salts, with the crystallite sizes 12 - 18 nm. The TEM images of the metal sulfide nanoparticles showed particles with spherical and rectangular shapes with crystallite sizes 4 - 35 nm.
- Full Text:
- Date Issued: 2015
Nudus amor formam non amat artificem : representations of gender in elegiac discourse
- Authors: Evans, Philippa A
- Date: 2015
- Subjects: Elegiac poetry , Gender identity in literature , Foucault, Michel, 1926-1984 , Butler, Judith, 1956- , Benjamin, Jessica , Mulvey, Laura , Tibullus , Propertius, Sextus , Sulpicia, active 1st century B.C. , Ovid, 43 B.C. - 17 or 18 A.D. Metamorphoses. Liber 10
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:3654 , http://hdl.handle.net/10962/d1017895
- Description: This thesis explores the representation of gender, desire, and identity in elegiac discourse. It does so through the lens of post‐structural and psychoanalytic theory, referring to the works of Michel Foucault, Judith Butler, Jessica Benjamin, and Laura Mulvey in their analyses of power, gender performativity, and subjectivity. Within this thesis, these concepts are applied primarily to the works of Tibullus, Propertius, and Sulpicia, ultimately demonstrating that the three love elegists seek, in their poetry, to construct subversive discourses which destabilise the categories by which gender and identity were determined in Augustan Rome. This discussion is supplemented by the investigation of Ovid’s use of elegiac discourse in Book 10 of his Metamorphoses, and the way in which it both comments upon Augustan love elegy and demonstrates a number of parallels with its thematic content. This thesis focuses especially on the representation of power relations within elegiac discourse, the various levels on which such relations operate and, finally, the possibilities for the contestation of and resistance to power, in addition to the motivations that might lie behind the poet‐lover’s frequent attraction and submission to it.
- Full Text:
- Date Issued: 2015
- Authors: Evans, Philippa A
- Date: 2015
- Subjects: Elegiac poetry , Gender identity in literature , Foucault, Michel, 1926-1984 , Butler, Judith, 1956- , Benjamin, Jessica , Mulvey, Laura , Tibullus , Propertius, Sextus , Sulpicia, active 1st century B.C. , Ovid, 43 B.C. - 17 or 18 A.D. Metamorphoses. Liber 10
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:3654 , http://hdl.handle.net/10962/d1017895
- Description: This thesis explores the representation of gender, desire, and identity in elegiac discourse. It does so through the lens of post‐structural and psychoanalytic theory, referring to the works of Michel Foucault, Judith Butler, Jessica Benjamin, and Laura Mulvey in their analyses of power, gender performativity, and subjectivity. Within this thesis, these concepts are applied primarily to the works of Tibullus, Propertius, and Sulpicia, ultimately demonstrating that the three love elegists seek, in their poetry, to construct subversive discourses which destabilise the categories by which gender and identity were determined in Augustan Rome. This discussion is supplemented by the investigation of Ovid’s use of elegiac discourse in Book 10 of his Metamorphoses, and the way in which it both comments upon Augustan love elegy and demonstrates a number of parallels with its thematic content. This thesis focuses especially on the representation of power relations within elegiac discourse, the various levels on which such relations operate and, finally, the possibilities for the contestation of and resistance to power, in addition to the motivations that might lie behind the poet‐lover’s frequent attraction and submission to it.
- Full Text:
- Date Issued: 2015
Spatial and temporal variations in trophic connectivity within an estuarine environment : benthic-pelagic and terrestrial-aquatic linkages via invertebrates and fishes
- Authors: Bergamino Roman, Leandro
- Date: 2015
- Subjects: Estuarine ecology -- South Africa , Marine invertebrates -- South Africa -- Ecology
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5921 , http://hdl.handle.net/10962/d1017799
- Description: Estuarine ecosystems are among the most biologically productive areas and they provide important ecosystem services such as erosion control, habitat and refugia for several species. These environments are characterized by the presence of a variety of organic matter sources due to their transitional position between rivers and the sea. The biotic compositions can undergo spatial and seasonal changes along the estuary due to the spatial and temporal fluctuations of environmental factors such as salinity, temperature and seston loads. Therefore, the different combinations of biotic and abiotic factors make each estuary a unique ecosystem. Because of this spatial and temporal complexity, the understanding of estuarine food web structure and which factors affect the trophic relationships within the ecosystem through space and time represent challenging tasks. Furthermore, estuaries are under an increasing number of anthropogenic perturbations because of the growing concentration of human populations in coastal areas. Knowledge of ecosystem structure and functioning is essential for effective conservation and management planning of coastal areas.In this dissertation, I combine the utilization of biological tracers to examine spatial and temporal variability in the food web structure within a small temperate and microtidal estuary located in South Africa. To this end, fatty acid profiles and stable isotope signatures were measured in several primary organic matter sources and consumers (including zooplankton, fishes and benthic invertebrates) during four consecutive seasons and in three different estuarine regions: upper, middle, and lower reaches. The three reaches had distinct habitat features of vegetation type and morphology, and in particular the lower reaches were colonized by the marsh grass Spartina maritima. Isotopic mixing models were used to estimate the relative contribution of each food source to the diets of invertebrates and fishes within the estuarine food web. The isotopic and fatty acid data showed similar results. In general, the lower reaches of the estuary were characterized by a higher deposition and assimilation by brachyuran crabs of carbon derived from marsh grass detritus, whiletowards the upper reaches a mixture of microphytobenthos and particulate organic matter (phytoplankton and detritus) was deposited and sustained the pelagic and benthic fauna. The highest deposition and assimilation of marsh grass detritus in the lower reaches of the estuary occurred during periods of low freshwater discharge (autumn and winter). In the upper reaches, microphytobenthos and suspended particulate organic matter were dominant basal food resources for the food web during all seasons. These results indicated that benthic consumers incorporated mainly local carbon sources from their local habitat.To clarify isotopic and fatty acid patterns I examined the trophic behaviour of the sesarmid crab Sesarma catenata through laboratory feeding experiments. Results from these experiments validated that decomposed leaves of riparian trees and the salt marsh plant S. maritima were the preferred food of the sesarmid crabs, potentially due to high bacterial loads. The remaining leaf material not assimilated by crabs, together with faecal material, are likely important subsidies for adjacent environments, hence representing an important energy pathway involving the microbial food chain. Furthermore, this dissertation showed the importance of mobile top predators as vectors energetically connecting distinct food chains within the estuary (i.e. littoral, benthic and pelagic). I concluded that a combination of physical (i.e. patterns of freshwater discharge and estuary morphology) and biological factors (i.e. organism feeding behaviour, mobility, primary productivity, the local vegetation type) influence the pattern of dominant primary organic matter sources, and therefore the food web structure along the estuarine environment. In particular, marsh grass detritus contributed substantially to the diets of estuarine fauna during periods of low freshwater discharge. Given the importance of the salt marsh habitat in providing trophic resources, it is important to preserve this environment to sustain the natural biota and ecosystem functioning.
- Full Text:
- Date Issued: 2015
- Authors: Bergamino Roman, Leandro
- Date: 2015
- Subjects: Estuarine ecology -- South Africa , Marine invertebrates -- South Africa -- Ecology
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5921 , http://hdl.handle.net/10962/d1017799
- Description: Estuarine ecosystems are among the most biologically productive areas and they provide important ecosystem services such as erosion control, habitat and refugia for several species. These environments are characterized by the presence of a variety of organic matter sources due to their transitional position between rivers and the sea. The biotic compositions can undergo spatial and seasonal changes along the estuary due to the spatial and temporal fluctuations of environmental factors such as salinity, temperature and seston loads. Therefore, the different combinations of biotic and abiotic factors make each estuary a unique ecosystem. Because of this spatial and temporal complexity, the understanding of estuarine food web structure and which factors affect the trophic relationships within the ecosystem through space and time represent challenging tasks. Furthermore, estuaries are under an increasing number of anthropogenic perturbations because of the growing concentration of human populations in coastal areas. Knowledge of ecosystem structure and functioning is essential for effective conservation and management planning of coastal areas.In this dissertation, I combine the utilization of biological tracers to examine spatial and temporal variability in the food web structure within a small temperate and microtidal estuary located in South Africa. To this end, fatty acid profiles and stable isotope signatures were measured in several primary organic matter sources and consumers (including zooplankton, fishes and benthic invertebrates) during four consecutive seasons and in three different estuarine regions: upper, middle, and lower reaches. The three reaches had distinct habitat features of vegetation type and morphology, and in particular the lower reaches were colonized by the marsh grass Spartina maritima. Isotopic mixing models were used to estimate the relative contribution of each food source to the diets of invertebrates and fishes within the estuarine food web. The isotopic and fatty acid data showed similar results. In general, the lower reaches of the estuary were characterized by a higher deposition and assimilation by brachyuran crabs of carbon derived from marsh grass detritus, whiletowards the upper reaches a mixture of microphytobenthos and particulate organic matter (phytoplankton and detritus) was deposited and sustained the pelagic and benthic fauna. The highest deposition and assimilation of marsh grass detritus in the lower reaches of the estuary occurred during periods of low freshwater discharge (autumn and winter). In the upper reaches, microphytobenthos and suspended particulate organic matter were dominant basal food resources for the food web during all seasons. These results indicated that benthic consumers incorporated mainly local carbon sources from their local habitat.To clarify isotopic and fatty acid patterns I examined the trophic behaviour of the sesarmid crab Sesarma catenata through laboratory feeding experiments. Results from these experiments validated that decomposed leaves of riparian trees and the salt marsh plant S. maritima were the preferred food of the sesarmid crabs, potentially due to high bacterial loads. The remaining leaf material not assimilated by crabs, together with faecal material, are likely important subsidies for adjacent environments, hence representing an important energy pathway involving the microbial food chain. Furthermore, this dissertation showed the importance of mobile top predators as vectors energetically connecting distinct food chains within the estuary (i.e. littoral, benthic and pelagic). I concluded that a combination of physical (i.e. patterns of freshwater discharge and estuary morphology) and biological factors (i.e. organism feeding behaviour, mobility, primary productivity, the local vegetation type) influence the pattern of dominant primary organic matter sources, and therefore the food web structure along the estuarine environment. In particular, marsh grass detritus contributed substantially to the diets of estuarine fauna during periods of low freshwater discharge. Given the importance of the salt marsh habitat in providing trophic resources, it is important to preserve this environment to sustain the natural biota and ecosystem functioning.
- Full Text:
- Date Issued: 2015
Transformation adaptation: developing a framework for donor organisation support of climate change adaptation in resource poor communities
- Authors: Dada, Rehana
- Date: 2015
- Subjects: Climatic changes , Human beings -- Effect of climate on , Acclimatization
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/4158 , vital:20560
- Description: Poor communities already face severe challenges in meeting their basic needs, whether because of poor income opportunities, inadequate service delivery, or degraded ecosystems that can no longer support the needs of people. Non profit organisations who provide support for development are also challenged by financial restrictions and social and political structures that prevent or limit project development. Climate change is understood to have the most severe impact on the most vulnerable communities and sectors of communities by reducing the availability and accessibility of basic resources such as water, food and energy, impacting severely on human health and wellbeing, and further reducing the capacity of ecosystems to support livelihoods. This will add a layer of significant new complications to the ability of poor communities to maintain or improve standards of living, and further challenge non profit organisations that support such communitiesAnticipatory adaptation to climate change can reduce some of the impacts of climate change, and also address some key development stresses. This thesis aims to provide a framework that is relevant for supporting adaptation to climate change within the context of resource poor communities in a developing country. Non profit organisations and donor agencies could support success and autonomy in adaptation processes by making provision for locally defined understanding of adaptation, and locally determined processes and programmes. This can be taken further into implementation of programming that addresses local short term development priorities alongside, or as part of long term adaptation work. The research followed a number of steps involving a multitude of techniques including literature review, interviews, a survey, consultation with an expert group, further consultation with stakeholders, and a final electronic review. Its outcome is a strategy that can be used to support climate change adaptation in resource poor communities. A definition for adaptation is proposed as an interpretation of adaptation that is relevant in this context. The intended end goal of adaptation as defined in this research is a better form of development that : supports a harmonious and respectful relationship between humans and their natural resource base; averts further destructive global change or at the very least prevents it from becoming unmanageable; and manages the impacts of past and ongoing destructive change so that there is lowest possible loss of natural, human, or cultural resources. The term transformative adaptation emerged from the research processes to describe adaptation to climate change that concurrently addresses development challenges, is grounded in community development aspirations, integrates programming work across multiple thematic areas and approaches, and addresses the causes of climate change within adaptation interventions. The following broad guidelines are used to inform programming within the framework of transformative adaptation : Human communities are faced with an enormous challenge resulting from global change and sociopolitical injustices; Well planned anticipatory adaptation can limit exposure and vulnerability to at least some of the projected impacts of climate change; Adaptation to climate change incorporates a reduction of vulnerability to underlying development stresses, alongside a reduction of vulnerability to specific climate change stresses; Existing development work forms the foundation for adaptation interventions, acknowledging the interdependence of social, natural and economic systems and the need to maintain their health; Adaptation decision making is community based, and acknowledges that resource poor communities are best placed to establish their own development needs, drive implementation of interventions in own spaces, and identify own limits to adaptation; Adaptation work incorporates mitigation objectives so that the causes of climate change are addressed as part of the strategy for coping with climate change; Adaptation programming acknowledges the strong interlinkages between, and integrates work across, the thematic areas of water security, food sovereignty, energy security, land security, human wellbeing and livelihood diversity; Adaptation uses a broad set of approaches that spans research, knowledge sharing, advocacy, and investment in technology and infrastructure; There is flexibility in project design and implementation to allow room for experimentation with new concepts, and also to change design as knowledge, understanding, and geophysical, biophysical and sociopolitical conditions change.
- Full Text:
- Date Issued: 2015
- Authors: Dada, Rehana
- Date: 2015
- Subjects: Climatic changes , Human beings -- Effect of climate on , Acclimatization
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/4158 , vital:20560
- Description: Poor communities already face severe challenges in meeting their basic needs, whether because of poor income opportunities, inadequate service delivery, or degraded ecosystems that can no longer support the needs of people. Non profit organisations who provide support for development are also challenged by financial restrictions and social and political structures that prevent or limit project development. Climate change is understood to have the most severe impact on the most vulnerable communities and sectors of communities by reducing the availability and accessibility of basic resources such as water, food and energy, impacting severely on human health and wellbeing, and further reducing the capacity of ecosystems to support livelihoods. This will add a layer of significant new complications to the ability of poor communities to maintain or improve standards of living, and further challenge non profit organisations that support such communitiesAnticipatory adaptation to climate change can reduce some of the impacts of climate change, and also address some key development stresses. This thesis aims to provide a framework that is relevant for supporting adaptation to climate change within the context of resource poor communities in a developing country. Non profit organisations and donor agencies could support success and autonomy in adaptation processes by making provision for locally defined understanding of adaptation, and locally determined processes and programmes. This can be taken further into implementation of programming that addresses local short term development priorities alongside, or as part of long term adaptation work. The research followed a number of steps involving a multitude of techniques including literature review, interviews, a survey, consultation with an expert group, further consultation with stakeholders, and a final electronic review. Its outcome is a strategy that can be used to support climate change adaptation in resource poor communities. A definition for adaptation is proposed as an interpretation of adaptation that is relevant in this context. The intended end goal of adaptation as defined in this research is a better form of development that : supports a harmonious and respectful relationship between humans and their natural resource base; averts further destructive global change or at the very least prevents it from becoming unmanageable; and manages the impacts of past and ongoing destructive change so that there is lowest possible loss of natural, human, or cultural resources. The term transformative adaptation emerged from the research processes to describe adaptation to climate change that concurrently addresses development challenges, is grounded in community development aspirations, integrates programming work across multiple thematic areas and approaches, and addresses the causes of climate change within adaptation interventions. The following broad guidelines are used to inform programming within the framework of transformative adaptation : Human communities are faced with an enormous challenge resulting from global change and sociopolitical injustices; Well planned anticipatory adaptation can limit exposure and vulnerability to at least some of the projected impacts of climate change; Adaptation to climate change incorporates a reduction of vulnerability to underlying development stresses, alongside a reduction of vulnerability to specific climate change stresses; Existing development work forms the foundation for adaptation interventions, acknowledging the interdependence of social, natural and economic systems and the need to maintain their health; Adaptation decision making is community based, and acknowledges that resource poor communities are best placed to establish their own development needs, drive implementation of interventions in own spaces, and identify own limits to adaptation; Adaptation work incorporates mitigation objectives so that the causes of climate change are addressed as part of the strategy for coping with climate change; Adaptation programming acknowledges the strong interlinkages between, and integrates work across, the thematic areas of water security, food sovereignty, energy security, land security, human wellbeing and livelihood diversity; Adaptation uses a broad set of approaches that spans research, knowledge sharing, advocacy, and investment in technology and infrastructure; There is flexibility in project design and implementation to allow room for experimentation with new concepts, and also to change design as knowledge, understanding, and geophysical, biophysical and sociopolitical conditions change.
- Full Text:
- Date Issued: 2015
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