Learning from the people : participatory rural appraisal, geography and rural development in the 'new' South Africa
- Binns, Tony, Hill, Trevor R, Nel, Etienne L
- Authors: Binns, Tony , Hill, Trevor R , Nel, Etienne L
- Date: 1997
- Language: English
- Type: Article
- Identifier: vital:6675 , http://hdl.handle.net/10962/d1006649
- Description: Top-down rural development strategies in Africa have generally not succeeded in raising living standards among the rural poor. It is argued that inappropriate development strategies have stemmed from methodologies that fail to appreciate the whole picture in rural communities, and in particular ignore local people's perceptions, needs and understanding. Participatory Rural Appraisal (PRA) represents a significant step forward in the design of methodologies and a selection of these techniques is evaluated. Many PRA methods have much in common with the field research methods that have been used by geographers over many years to interpret people-environment relationships. A research investigation in Eastern Cape Province, South Africa, suggests that geographers could have an important role to play in this area of applied research and, in particular, in the context of post-apartheid South Africa there is an urgent challenge to be met in promoting rural development in poor, former black Homeland areas.
- Full Text:
- Date Issued: 1997
- Authors: Binns, Tony , Hill, Trevor R , Nel, Etienne L
- Date: 1997
- Language: English
- Type: Article
- Identifier: vital:6675 , http://hdl.handle.net/10962/d1006649
- Description: Top-down rural development strategies in Africa have generally not succeeded in raising living standards among the rural poor. It is argued that inappropriate development strategies have stemmed from methodologies that fail to appreciate the whole picture in rural communities, and in particular ignore local people's perceptions, needs and understanding. Participatory Rural Appraisal (PRA) represents a significant step forward in the design of methodologies and a selection of these techniques is evaluated. Many PRA methods have much in common with the field research methods that have been used by geographers over many years to interpret people-environment relationships. A research investigation in Eastern Cape Province, South Africa, suggests that geographers could have an important role to play in this area of applied research and, in particular, in the context of post-apartheid South Africa there is an urgent challenge to be met in promoting rural development in poor, former black Homeland areas.
- Full Text:
- Date Issued: 1997
Phloem loading in the sucrose-export-defective (SXD-1) mutant maize is limited by callose deposition at plasmodesmata in bundle sheath-vascular parenchyma interface
- Botha, Christiaan E J, Cross, Robin H M, Van Bel, A J E, Peter, Craig I
- Authors: Botha, Christiaan E J , Cross, Robin H M , Van Bel, A J E , Peter, Craig I
- Date: 2000
- Language: English
- Type: Article
- Identifier: vital:6503 , http://hdl.handle.net/10962/d1005926
- Description: Using Lucifer Yellow we have demonstrated that the phloem-loading pathway from the mesophyll to the bundle sheath-vascular parenchyma interface in Zea mays source leaves follows a symplasmic route in small and intermediate vascular bundles in control as well as in the green sections of mutant sucrose-export-defective (SXD-1) plants. In the anthocyanin-rich mutant leaf sections, Lucifer Yellow transport was prohibited along the same path, at the bundle sheath-vascular parenchyma interface in particular. Plasmodesmata at the latter interface in SXD-1 anthocyanin-rich leaf sections appear to be structurally altered through callose deposition at the plasmodesmal orifices. We suggest that a transport bottleneck at the bundle sheath-vascular parenchyma interface is thus orchestrated and regulated through callose formation, preventing symplasmic transport across this important loading interface.
- Full Text:
- Date Issued: 2000
- Authors: Botha, Christiaan E J , Cross, Robin H M , Van Bel, A J E , Peter, Craig I
- Date: 2000
- Language: English
- Type: Article
- Identifier: vital:6503 , http://hdl.handle.net/10962/d1005926
- Description: Using Lucifer Yellow we have demonstrated that the phloem-loading pathway from the mesophyll to the bundle sheath-vascular parenchyma interface in Zea mays source leaves follows a symplasmic route in small and intermediate vascular bundles in control as well as in the green sections of mutant sucrose-export-defective (SXD-1) plants. In the anthocyanin-rich mutant leaf sections, Lucifer Yellow transport was prohibited along the same path, at the bundle sheath-vascular parenchyma interface in particular. Plasmodesmata at the latter interface in SXD-1 anthocyanin-rich leaf sections appear to be structurally altered through callose deposition at the plasmodesmal orifices. We suggest that a transport bottleneck at the bundle sheath-vascular parenchyma interface is thus orchestrated and regulated through callose formation, preventing symplasmic transport across this important loading interface.
- Full Text:
- Date Issued: 2000
Plasmodesmatal frequency in relation to short-distance transport and phloem loading in leaves of barley (Hordeum vulgare). Phloem is not loaded directly from the symplast
- Botha, Christiaan E J, Cross, Robin H M
- Authors: Botha, Christiaan E J , Cross, Robin H M
- Date: 1997
- Language: English
- Type: Article
- Identifier: vital:6504 , http://hdl.handle.net/10962/d1005928
- Description: We investigated the phloem loading pathway in barley, by determining plasmodesmatal frequencies at the electron microscope level for both intermediate and small blade bundles of mature barley leaves. Lucifer yellow was injected intercellularly into bundle sheath, vascular parenchyma, and thin-walled sieve tubes. Passage of this symplastically transported dye was monitored with an epifluorescence microscope under blue light. Low plasmodesmatal frequencies endarch to the bundle sheath cells are relatively low for most interfaces terminating at the thin- and thick-walled sieve tubes within this C3 species. Lack of connections between vascular parenchyma and sieve tubes, and low frequencies (0.5% plasmodesmata per μm cell wall interface) of connections between vascular parenchyma and companion cells, as well as the very low frequency of pore-plasmodesmatal connections between companion cells and sieve tubes in small bundles (0.2% plasmodesmata per μm cell wall interface), suggest that the companion cell-sieve tube complex is symplastically isolated from other vascular parenchyma cells in small bundles. The degree of cellular connectivity and the potential isolation of the companion cell-sieve tube complex was determined electrophysiologically, using an electrometer coupled to microcapillary electrodes. The less negative cell potential {average -52 mV) from mesophyll to the vascular parenchyma cells contrasted sharply with the more negative potential (-122.5 mV) recorded for the companion cell-thin-walled sieve tube complex. Although intercellular injection of lucifer yellow clearly demonstrated rapid (0.75 μm s-1) longitudinal and radial transport in the bundle sheath-vascular parenchyma complex, as well as from the bundle sheath through transverse veins to adjacent longitudinal veins, we were neither able to detect nor present unequivocal evidence in support of the symplastic connectivity of the sieve tubes to the vascular parenchyma. Injection of the companion cell-sieve tube complex, did not demonstrate backward connectivity to the bundle sheath. We conclude that the low plasmodesmatal frequencies, coupled with a two-domain electropotential zonation configuration, and the negative transport experiments using lucifer yellow, precludes symplastic phloem loading in barley leaves.
- Full Text:
- Date Issued: 1997
- Authors: Botha, Christiaan E J , Cross, Robin H M
- Date: 1997
- Language: English
- Type: Article
- Identifier: vital:6504 , http://hdl.handle.net/10962/d1005928
- Description: We investigated the phloem loading pathway in barley, by determining plasmodesmatal frequencies at the electron microscope level for both intermediate and small blade bundles of mature barley leaves. Lucifer yellow was injected intercellularly into bundle sheath, vascular parenchyma, and thin-walled sieve tubes. Passage of this symplastically transported dye was monitored with an epifluorescence microscope under blue light. Low plasmodesmatal frequencies endarch to the bundle sheath cells are relatively low for most interfaces terminating at the thin- and thick-walled sieve tubes within this C3 species. Lack of connections between vascular parenchyma and sieve tubes, and low frequencies (0.5% plasmodesmata per μm cell wall interface) of connections between vascular parenchyma and companion cells, as well as the very low frequency of pore-plasmodesmatal connections between companion cells and sieve tubes in small bundles (0.2% plasmodesmata per μm cell wall interface), suggest that the companion cell-sieve tube complex is symplastically isolated from other vascular parenchyma cells in small bundles. The degree of cellular connectivity and the potential isolation of the companion cell-sieve tube complex was determined electrophysiologically, using an electrometer coupled to microcapillary electrodes. The less negative cell potential {average -52 mV) from mesophyll to the vascular parenchyma cells contrasted sharply with the more negative potential (-122.5 mV) recorded for the companion cell-thin-walled sieve tube complex. Although intercellular injection of lucifer yellow clearly demonstrated rapid (0.75 μm s-1) longitudinal and radial transport in the bundle sheath-vascular parenchyma complex, as well as from the bundle sheath through transverse veins to adjacent longitudinal veins, we were neither able to detect nor present unequivocal evidence in support of the symplastic connectivity of the sieve tubes to the vascular parenchyma. Injection of the companion cell-sieve tube complex, did not demonstrate backward connectivity to the bundle sheath. We conclude that the low plasmodesmatal frequencies, coupled with a two-domain electropotential zonation configuration, and the negative transport experiments using lucifer yellow, precludes symplastic phloem loading in barley leaves.
- Full Text:
- Date Issued: 1997
Towards reconciliation of structure with function in plasmodesmata—who is the gatekeeper?
- Botha, Christiaan E J, Cross, Robin H M
- Authors: Botha, Christiaan E J , Cross, Robin H M
- Date: 2000
- Language: English
- Type: Article
- Identifier: vital:6497 , http://hdl.handle.net/10962/d1004493
- Description: Whilst the structure of higher plant plasmodesmata was first described by Robards (1963. Desmotubule—a plasmodesmatal substructure. Nature 218, 784), and despite many subsequent intensive investigations, there is still much that remains unclear relating to their ultrastructure and functioning in higher plants. We have examined chemically fixed plant material, and suggest that the conformational changes seen in plasmodesmatal substructure, particularly the deposition of electron-dense extra-plasmodesmal material, is linked to either manipulation of the hormonal balance (as in Avocado fruit), or of osmotic potential in leaf blade material. These changes result in the deposition of β 1,3-glucan (callose) at the neck region of these plasmodesmata. This electron-dense material is deposited at the neck region of plasmodesmata, and forms a collar-like structure. The formation of a collar is shown to be coupled with loss of lucence within the cytoplasmic sleeve. The formation of a collar at the plasmodesmatal orifice thus results in encapsulation and closure of the plasmodesmatal orifice. Closure of the orifice coincides with a loss of electron-lucence and a lack of resolution of the desmotubule. These ultrastructural changes are potentially significant and could contribute to, result in, or assist in the down-regulation of cell to cell trafficking via plasmodesmata.
- Full Text:
- Date Issued: 2000
- Authors: Botha, Christiaan E J , Cross, Robin H M
- Date: 2000
- Language: English
- Type: Article
- Identifier: vital:6497 , http://hdl.handle.net/10962/d1004493
- Description: Whilst the structure of higher plant plasmodesmata was first described by Robards (1963. Desmotubule—a plasmodesmatal substructure. Nature 218, 784), and despite many subsequent intensive investigations, there is still much that remains unclear relating to their ultrastructure and functioning in higher plants. We have examined chemically fixed plant material, and suggest that the conformational changes seen in plasmodesmatal substructure, particularly the deposition of electron-dense extra-plasmodesmal material, is linked to either manipulation of the hormonal balance (as in Avocado fruit), or of osmotic potential in leaf blade material. These changes result in the deposition of β 1,3-glucan (callose) at the neck region of these plasmodesmata. This electron-dense material is deposited at the neck region of plasmodesmata, and forms a collar-like structure. The formation of a collar is shown to be coupled with loss of lucence within the cytoplasmic sleeve. The formation of a collar at the plasmodesmatal orifice thus results in encapsulation and closure of the plasmodesmatal orifice. Closure of the orifice coincides with a loss of electron-lucence and a lack of resolution of the desmotubule. These ultrastructural changes are potentially significant and could contribute to, result in, or assist in the down-regulation of cell to cell trafficking via plasmodesmata.
- Full Text:
- Date Issued: 2000
The comparison of in vitro release methods for the evaluation of oxytocin release from Pluronic® F127 parenteral formulations
- Chaibva, Faith A, Walker, Roderick B
- Authors: Chaibva, Faith A , Walker, Roderick B
- Date: 2007
- Language: English
- Type: Article
- Identifier: vital:6351 , http://hdl.handle.net/10962/d1006033
- Description: The objective of these studies was to develop a discriminatory in vitro release test for assessing formulation factors that may affect oxytocin (OT) release during formulation development studies of a Pluronic® F127 OT in situ gel-forming parenteral dosage form. An appropriate release assessment method should be able to discriminate between the performance of different formulation compositions (1, 2), and this was the primary criterion used for selection of an appropriate test procedure during the test method development process. ANOVA and the difference (f1) and similarity (f2)factors were used to evaluate the discriminatory behavior of different test methods that were investigated in these studies. The in vitro release tests that were investigated included the use of USP Apparatus 1, 2, and 3; a dialysis bag in USP Apparatus 2; and a membrane-less diffusion method. It was concluded that the use of USP Apparatus 3 was best able to discriminate between OT release for the different formulations tested. USP Apparatus 3 was thus considered the most suitable in vitro release test apparatus for studying formulation factors affecting OT release during the development of a parenteral dosage form prepared using Pluronic® F127.
- Full Text:
- Date Issued: 2007
- Authors: Chaibva, Faith A , Walker, Roderick B
- Date: 2007
- Language: English
- Type: Article
- Identifier: vital:6351 , http://hdl.handle.net/10962/d1006033
- Description: The objective of these studies was to develop a discriminatory in vitro release test for assessing formulation factors that may affect oxytocin (OT) release during formulation development studies of a Pluronic® F127 OT in situ gel-forming parenteral dosage form. An appropriate release assessment method should be able to discriminate between the performance of different formulation compositions (1, 2), and this was the primary criterion used for selection of an appropriate test procedure during the test method development process. ANOVA and the difference (f1) and similarity (f2)factors were used to evaluate the discriminatory behavior of different test methods that were investigated in these studies. The in vitro release tests that were investigated included the use of USP Apparatus 1, 2, and 3; a dialysis bag in USP Apparatus 2; and a membrane-less diffusion method. It was concluded that the use of USP Apparatus 3 was best able to discriminate between OT release for the different formulations tested. USP Apparatus 3 was thus considered the most suitable in vitro release test apparatus for studying formulation factors affecting OT release during the development of a parenteral dosage form prepared using Pluronic® F127.
- Full Text:
- Date Issued: 2007
Effects of patch-size on populations of intertidal limpets, Siphonaria spp., in a linear landscape
- Cole, Victoria J, Johnson, Linda G, McQuaid, Christopher D
- Authors: Cole, Victoria J , Johnson, Linda G , McQuaid, Christopher D
- Date: 2012
- Language: English
- Type: Article
- Identifier: vital:6845 , http://hdl.handle.net/10962/d1011050
- Description: Organisms with different life-histories and abilities to disperse often utilise habitat patches in different ways. We investigated the influence of the size of patches of rock (separated by stretches of sand) on the density of pulmonate limpets (Siphonaria spp.) along 1500 km of the linear landscape of the South African coastline. We compared the influence of patch-size on two congeneric species with different modes of development, S. serrata a direct developer, and S. concinna a planktonic developer. We tested the spatial and temporal consistency of the effects of patch-size by sampling 7 independent regions spanning the distributional range of both species of limpets, and by sampling one region at monthly intervals for 1 year. Within each region or month, 4 small patches (<20 m in length) interspersed with the 4 large patches (>60 m in length) were sampled. Across the entire geographic range and throughout the year, there were more of both species of limpets in large patches than in small patches. In most regions, there was greater variability in large patches than small patches. Variability within patches in a single region was similar throughout the year, with greater variability of both species in large than in small patches. We found little influence of the mode of development on the response of limpets to patch-size. Our findings highlight the importance of understanding patterns of distribution of species with respect to habitat heterogeneity in linear landscapes, and contradict the idea that organism mobility at an early ontogenetic stage directly affects habitat use.
- Full Text:
- Date Issued: 2012
- Authors: Cole, Victoria J , Johnson, Linda G , McQuaid, Christopher D
- Date: 2012
- Language: English
- Type: Article
- Identifier: vital:6845 , http://hdl.handle.net/10962/d1011050
- Description: Organisms with different life-histories and abilities to disperse often utilise habitat patches in different ways. We investigated the influence of the size of patches of rock (separated by stretches of sand) on the density of pulmonate limpets (Siphonaria spp.) along 1500 km of the linear landscape of the South African coastline. We compared the influence of patch-size on two congeneric species with different modes of development, S. serrata a direct developer, and S. concinna a planktonic developer. We tested the spatial and temporal consistency of the effects of patch-size by sampling 7 independent regions spanning the distributional range of both species of limpets, and by sampling one region at monthly intervals for 1 year. Within each region or month, 4 small patches (<20 m in length) interspersed with the 4 large patches (>60 m in length) were sampled. Across the entire geographic range and throughout the year, there were more of both species of limpets in large patches than in small patches. In most regions, there was greater variability in large patches than small patches. Variability within patches in a single region was similar throughout the year, with greater variability of both species in large than in small patches. We found little influence of the mode of development on the response of limpets to patch-size. Our findings highlight the importance of understanding patterns of distribution of species with respect to habitat heterogeneity in linear landscapes, and contradict the idea that organism mobility at an early ontogenetic stage directly affects habitat use.
- Full Text:
- Date Issued: 2012
Patterns of sexual size dimorphism in African cichlid fishes
- Erlandsson, A, Ribbink, Anthony J
- Authors: Erlandsson, A , Ribbink, Anthony J
- Date: 1997
- Language: English
- Type: Article
- Identifier: vital:7135 , http://hdl.handle.net/10962/d1011778
- Description: Although the Cichlidae is a well-studied family of African fishes, the evolution of sexual size dimorphism (SSD) and its relation to life-history, behaviour, feeding and habitat have not been comparatively examined. The investigation of SSD reported here was based on a study of the scientific literature. Prerequisites to such studies are records of maximum size of adult males and females. Disappointingly few authors published such measurements, so the data are fewer than anticipated given that the cichlids are such a species-rich group. Now that this omission has been noted, it is hoped that investigations of the future will include information on maximum size of adults of both sexes. Data from 215 species showed great variation in the degree and direction of SSD, without any really strong trends being evident. In the majority of species, males were larger than females or there was no size difference between the sexes. In 10% (21 species), females were larger than males. All of these are lacustrine, tend to live in deep water, often over muddy substrata and to feed to a greater extent than expected on non-defendable food sources. The degree of SSD increases with increasing body size in species where males are the larger sex and decreases in species where females are the larger In territorial species, in which competition between territorial males is intensive, males are the larger sex. The expectation that polygynous cichlids would show a more marked degree of SSD than monogamous species was not met. Larger size in females (with one exception) occurs in mouthbrooding species only. Males are the larger sex in substratum brooders. It seems that the degree and direction of sexual size dimorphism in cichlids is a consequence of a balance of natural and sexual selection, but there is a need to increase the sample size to understand the interplay of these selection pressures and to establish the validity of the emerging trends.
- Full Text: false
- Date Issued: 1997
- Authors: Erlandsson, A , Ribbink, Anthony J
- Date: 1997
- Language: English
- Type: Article
- Identifier: vital:7135 , http://hdl.handle.net/10962/d1011778
- Description: Although the Cichlidae is a well-studied family of African fishes, the evolution of sexual size dimorphism (SSD) and its relation to life-history, behaviour, feeding and habitat have not been comparatively examined. The investigation of SSD reported here was based on a study of the scientific literature. Prerequisites to such studies are records of maximum size of adult males and females. Disappointingly few authors published such measurements, so the data are fewer than anticipated given that the cichlids are such a species-rich group. Now that this omission has been noted, it is hoped that investigations of the future will include information on maximum size of adults of both sexes. Data from 215 species showed great variation in the degree and direction of SSD, without any really strong trends being evident. In the majority of species, males were larger than females or there was no size difference between the sexes. In 10% (21 species), females were larger than males. All of these are lacustrine, tend to live in deep water, often over muddy substrata and to feed to a greater extent than expected on non-defendable food sources. The degree of SSD increases with increasing body size in species where males are the larger sex and decreases in species where females are the larger In territorial species, in which competition between territorial males is intensive, males are the larger sex. The expectation that polygynous cichlids would show a more marked degree of SSD than monogamous species was not met. Larger size in females (with one exception) occurs in mouthbrooding species only. Males are the larger sex in substratum brooders. It seems that the degree and direction of sexual size dimorphism in cichlids is a consequence of a balance of natural and sexual selection, but there is a need to increase the sample size to understand the interplay of these selection pressures and to establish the validity of the emerging trends.
- Full Text: false
- Date Issued: 1997
The Development of Palladium(II)-Specific Amine-Functionalized Silica-Based Microparticles: Adsorption and Column Separation Studies
- Fayemi, Omolola E, Ogunlaja, Adeniyi S, Antunes, Edith M, Nyokong, Tebello, Tshentu, Zenixole R
- Authors: Fayemi, Omolola E , Ogunlaja, Adeniyi S , Antunes, Edith M , Nyokong, Tebello , Tshentu, Zenixole R
- Date: 2015
- Language: English
- Type: Article
- Identifier: vital:7269 , http://hdl.handle.net/10962/d1020278
- Description: The adsorption and separation of platinum(IV) and palladium(II) chlorido species ([PtCl6]2− and [PdCl4]2−) on silica-based microparticles functionalized with ammonium centers based on ethylenediamine (EDA), diethylenetriamine (DETA), triethylenetriamine (TETA) and tris-(2-aminoethyl)amine (TAEA) were investigated. The functionalized sorbent materials were characterized using SEM, XPS, BET, and FTIR. The sorbents were used in the batch and column study for adsorption and selective separation of [PtCl62− and PdCl4]2−. The adsorption model for both [PtCl6]2− and [PdCl4]2− on the different sorbent materials fitted the Freundlich isotherm with R2 values > 0.99. The S-TETA sorbent material was palladium(II) specific. Pd(II) loaded on the silica column was recovered using 3% m/v thiourea solution as the eluting agent. Separation of platinum and palladium was achieved by selective stripping of [PtCl6]2− with 0.5 M of NaClO4 in 1.0 M HCl while Pd(II) was eluted with 0.5 M thiourea in 1.0 M HCl. The separation of palladium (Pd) from a mixture containing platinum (Pt), iridium (Ir), and rhodium (Rh) was successful on silica functionalized with triethylenetriamine (TETA) showing specificity for palladium(II) and a loading capacity of 0.27 mg/g. S-TETA showed potential for use in the recovery of palladium from platinum group metals such as from solutions of worn out automobile emission control catalytic convertors and other secondary sources. , Original publication is available at http://dx.doi.org/10.1080/01496395.2014.978017
- Full Text: false
- Date Issued: 2015
- Authors: Fayemi, Omolola E , Ogunlaja, Adeniyi S , Antunes, Edith M , Nyokong, Tebello , Tshentu, Zenixole R
- Date: 2015
- Language: English
- Type: Article
- Identifier: vital:7269 , http://hdl.handle.net/10962/d1020278
- Description: The adsorption and separation of platinum(IV) and palladium(II) chlorido species ([PtCl6]2− and [PdCl4]2−) on silica-based microparticles functionalized with ammonium centers based on ethylenediamine (EDA), diethylenetriamine (DETA), triethylenetriamine (TETA) and tris-(2-aminoethyl)amine (TAEA) were investigated. The functionalized sorbent materials were characterized using SEM, XPS, BET, and FTIR. The sorbents were used in the batch and column study for adsorption and selective separation of [PtCl62− and PdCl4]2−. The adsorption model for both [PtCl6]2− and [PdCl4]2− on the different sorbent materials fitted the Freundlich isotherm with R2 values > 0.99. The S-TETA sorbent material was palladium(II) specific. Pd(II) loaded on the silica column was recovered using 3% m/v thiourea solution as the eluting agent. Separation of platinum and palladium was achieved by selective stripping of [PtCl6]2− with 0.5 M of NaClO4 in 1.0 M HCl while Pd(II) was eluted with 0.5 M thiourea in 1.0 M HCl. The separation of palladium (Pd) from a mixture containing platinum (Pt), iridium (Ir), and rhodium (Rh) was successful on silica functionalized with triethylenetriamine (TETA) showing specificity for palladium(II) and a loading capacity of 0.27 mg/g. S-TETA showed potential for use in the recovery of palladium from platinum group metals such as from solutions of worn out automobile emission control catalytic convertors and other secondary sources. , Original publication is available at http://dx.doi.org/10.1080/01496395.2014.978017
- Full Text: false
- Date Issued: 2015
The development of Palladium(II)-specific amine-functionalized silica-based microparticles : adsorption and column separation studies
- Fayemi, Omolola E, Ogunlaja, Adeniyi S, Antunes, Edith M, Nyokong, Tebello, Tshentu, Zenixole R
- Authors: Fayemi, Omolola E , Ogunlaja, Adeniyi S , Antunes, Edith M , Nyokong, Tebello , Tshentu, Zenixole R
- Date: 2015
- Language: English
- Type: Article
- Identifier: vital:7270 , http://hdl.handle.net/10962/d1020285
- Description: The adsorption and separation of platinum(IV) and palladium(II) chlorido species ([PtCl6]2− and [PdCl4]2−) on silica-based microparticles functionalized with ammonium centers based on ethylenediamine (EDA), diethylenetriamine (DETA), triethylenetriamine (TETA) and tris-(2-aminoethyl)amine (TAEA) were investigated. The functionalized sorbent materials were characterized using SEM, XPS, BET, and FTIR. The sorbents were used in the batch and column study for adsorption and selective separation of [PtCl62− and PdCl4]2−. The adsorption model for both [PtCl6]2− and [PdCl4]2− on the different sorbent materials fitted the Freundlich isotherm with R2 values > 0.99. The S-TETA sorbent material was palladium(II) specific. Pd(II) loaded on the silica column was recovered using 3% m/v thiourea solution as the eluting agent. Separation of platinum and palladium was achieved by selective stripping of [PtCl6]2− with 0.5 M of NaClO4 in 1.0 M HCl while Pd(II) was eluted with 0.5 M thiourea in 1.0 M HCl. The separation of palladium (Pd) from a mixture containing platinum (Pt), iridium (Ir), and rhodium (Rh) was successful on silica functionalized with triethylenetriamine (TETA) showing specificity for palladium(II) and a loading capacity of 0.27 mg/g. S-TETA showed potential for use in the recovery of palladium from platinum group metals such as from solutions of worn out automobile emission control catalytic convertors and other secondary sources. , Original publication is available at http://dx.doi.org/10.1080/01496395.2014.978017
- Full Text: false
- Date Issued: 2015
- Authors: Fayemi, Omolola E , Ogunlaja, Adeniyi S , Antunes, Edith M , Nyokong, Tebello , Tshentu, Zenixole R
- Date: 2015
- Language: English
- Type: Article
- Identifier: vital:7270 , http://hdl.handle.net/10962/d1020285
- Description: The adsorption and separation of platinum(IV) and palladium(II) chlorido species ([PtCl6]2− and [PdCl4]2−) on silica-based microparticles functionalized with ammonium centers based on ethylenediamine (EDA), diethylenetriamine (DETA), triethylenetriamine (TETA) and tris-(2-aminoethyl)amine (TAEA) were investigated. The functionalized sorbent materials were characterized using SEM, XPS, BET, and FTIR. The sorbents were used in the batch and column study for adsorption and selective separation of [PtCl62− and PdCl4]2−. The adsorption model for both [PtCl6]2− and [PdCl4]2− on the different sorbent materials fitted the Freundlich isotherm with R2 values > 0.99. The S-TETA sorbent material was palladium(II) specific. Pd(II) loaded on the silica column was recovered using 3% m/v thiourea solution as the eluting agent. Separation of platinum and palladium was achieved by selective stripping of [PtCl6]2− with 0.5 M of NaClO4 in 1.0 M HCl while Pd(II) was eluted with 0.5 M thiourea in 1.0 M HCl. The separation of palladium (Pd) from a mixture containing platinum (Pt), iridium (Ir), and rhodium (Rh) was successful on silica functionalized with triethylenetriamine (TETA) showing specificity for palladium(II) and a loading capacity of 0.27 mg/g. S-TETA showed potential for use in the recovery of palladium from platinum group metals such as from solutions of worn out automobile emission control catalytic convertors and other secondary sources. , Original publication is available at http://dx.doi.org/10.1080/01496395.2014.978017
- Full Text: false
- Date Issued: 2015
Bleak future for multi-party elections in Kenya
- Authors: Fox, Roddy C
- Date: 1996
- Language: English
- Type: Article
- Identifier: vital:6683 , http://hdl.handle.net/10962/d1006681
- Description: With attention turning towards Kenya's second multi-party elections, due to be held before the end of 1997, it is imperative to look back to the flaws in the system which helped deliver President Daniel arap Moi and the Kenya African National Union (KANU) their victories in 1992. At present there is no sign of these defects being eradicated and the creation of new districts since then has demonstrated the Government's intention of enhancing an already biased structure. The underlying distribution of tribes and ethnic groups has had a fundamental impact on the electoral geography of Kenya, since they have controlled the delimitation of both the parliamentary constituencies and the administrative machinery of the whole country.
- Full Text:
- Date Issued: 1996
- Authors: Fox, Roddy C
- Date: 1996
- Language: English
- Type: Article
- Identifier: vital:6683 , http://hdl.handle.net/10962/d1006681
- Description: With attention turning towards Kenya's second multi-party elections, due to be held before the end of 1997, it is imperative to look back to the flaws in the system which helped deliver President Daniel arap Moi and the Kenya African National Union (KANU) their victories in 1992. At present there is no sign of these defects being eradicated and the creation of new districts since then has demonstrated the Government's intention of enhancing an already biased structure. The underlying distribution of tribes and ethnic groups has had a fundamental impact on the electoral geography of Kenya, since they have controlled the delimitation of both the parliamentary constituencies and the administrative machinery of the whole country.
- Full Text:
- Date Issued: 1996
Biogeographic and nearshore–offshore trends in isotope ratios of intertidal mussels and their food sources around the coast of southern Africa
- Hill, Jaclyn M, McQuaid, Christopher D, Kaehler, Sven
- Authors: Hill, Jaclyn M , McQuaid, Christopher D , Kaehler, Sven
- Date: 2006
- Language: English
- Type: text , Article
- Identifier: vital:6878 , http://hdl.handle.net/10962/d1011633
- Description: There are broad differences in oceanography and primary production around the southern African coast that are likely to give rise to major differences in trophic pathways. Stable isotope ratios provide integrated information on trophic relationships, yet there has been limited research on geographic variation in isotopic composition of marine consumers and their food. In this study, δ13C and δ15N of suspended particulate matter (SPM), intertidal mussels and common macroalgae along the southern African coastline were explored. Nearshore–offshore isotope trends as well as biogeographic and temporal patterns in isotopic ratios of mussel tissue, macroalgae and SPM were investigated at 12 sites along the coast from Namibia to the Mozambique border. SPM exhibited overall trends of nearshore 13C depletion from south-west to north-east along the coastline and from nearshore (0 km) to offshore (10 km) waters, in both cases suggesting a shift from a nearshore signature strongly influenced by macroalgal detritus to one more representative of oceanic phytoplankton. With one exception it was possible, using discriminant analysis, to categorize mussel populations into 4 geographic groups, on the basis of both carbon and nitrogen signatures: the east coast, the south-east coast, the south-west coast and the west coast. Macroalgae showed no consistent biogeographic trends and need to be examined in greater detail to relate nearshore SPM values to living macroalgal signatures. A linear mixing model indicated that mussels along the entire coastline generally demonstrated more than 50% dependence on nearshore carbon and nitrogen, emphasizing the importance of nearshore primary production to intertidal consumers.
- Full Text:
- Date Issued: 2006
- Authors: Hill, Jaclyn M , McQuaid, Christopher D , Kaehler, Sven
- Date: 2006
- Language: English
- Type: text , Article
- Identifier: vital:6878 , http://hdl.handle.net/10962/d1011633
- Description: There are broad differences in oceanography and primary production around the southern African coast that are likely to give rise to major differences in trophic pathways. Stable isotope ratios provide integrated information on trophic relationships, yet there has been limited research on geographic variation in isotopic composition of marine consumers and their food. In this study, δ13C and δ15N of suspended particulate matter (SPM), intertidal mussels and common macroalgae along the southern African coastline were explored. Nearshore–offshore isotope trends as well as biogeographic and temporal patterns in isotopic ratios of mussel tissue, macroalgae and SPM were investigated at 12 sites along the coast from Namibia to the Mozambique border. SPM exhibited overall trends of nearshore 13C depletion from south-west to north-east along the coastline and from nearshore (0 km) to offshore (10 km) waters, in both cases suggesting a shift from a nearshore signature strongly influenced by macroalgal detritus to one more representative of oceanic phytoplankton. With one exception it was possible, using discriminant analysis, to categorize mussel populations into 4 geographic groups, on the basis of both carbon and nitrogen signatures: the east coast, the south-east coast, the south-west coast and the west coast. Macroalgae showed no consistent biogeographic trends and need to be examined in greater detail to relate nearshore SPM values to living macroalgal signatures. A linear mixing model indicated that mussels along the entire coastline generally demonstrated more than 50% dependence on nearshore carbon and nitrogen, emphasizing the importance of nearshore primary production to intertidal consumers.
- Full Text:
- Date Issued: 2006
Travelling stallions in and adjacent to Brycheiniog
- Authors: Lewis, Colin A
- Date: 1989
- Language: English
- Type: Article
- Identifier: vital:6696 , http://hdl.handle.net/10962/d1006732
- Description: [From the introduction]: Horses played a major role in the transport system in Britain until, in the years following the conclusion of the First World War, they were gradually ousted by motor vehicles. In 1917, when the first reasonably complete equine census of Britain was undertaken, there were 2,650,773 horses in the country, 1,115,920 of which were used for agricultural purposes (Chivers, 1976). Horse breeding was therefore of great importance and a variety of attempts was made to improve the quality of horses by subsidising stallions that travelled the countryside during the breeding season, and that were available, at a fee, for the service of mares. This paper describes some of the routes followed by stallions that formerly travelled in Brycheiniog and adjacent counties.
- Full Text: false
- Date Issued: 1989
- Authors: Lewis, Colin A
- Date: 1989
- Language: English
- Type: Article
- Identifier: vital:6696 , http://hdl.handle.net/10962/d1006732
- Description: [From the introduction]: Horses played a major role in the transport system in Britain until, in the years following the conclusion of the First World War, they were gradually ousted by motor vehicles. In 1917, when the first reasonably complete equine census of Britain was undertaken, there were 2,650,773 horses in the country, 1,115,920 of which were used for agricultural purposes (Chivers, 1976). Horse breeding was therefore of great importance and a variety of attempts was made to improve the quality of horses by subsidising stallions that travelled the countryside during the breeding season, and that were available, at a fee, for the service of mares. This paper describes some of the routes followed by stallions that formerly travelled in Brycheiniog and adjacent counties.
- Full Text: false
- Date Issued: 1989
6-Hydroxymelatonin protects against cyanide induced oxidative stress in rat brain homogenates
- Maharaj, Deepa S, Walker, Roderick B, Glass, Beverley D, Daya, Santylal
- Authors: Maharaj, Deepa S , Walker, Roderick B , Glass, Beverley D , Daya, Santylal
- Date: 2003
- Language: English
- Type: Article , text
- Identifier: vital:6405 , http://hdl.handle.net/10962/d1006478
- Description: Both 6-hydroxymelatonin and N-acetyl-N-formyl-5-methoxykynurenamine are photodegradants and enzymatic metabolites of melatonin and are known to retain equipotent activity against potassium cyanide-induced superoxide generation compared to melatonin. It is not clear whether one or both of these metabolites is responsible for this effect. The present study therefore investigates the possible manner in which 6-hydroxymelatonin protects against oxidative stress induced by cyanide in rat brain homogenates. We examined the ability of 6-hydroxymelatonin to scavenge KCN-induced superoxide anion generation as well as lipid peroxidation. In addition, we also examined the effect of this indole on lactate dehydrogenase activity (LDH) as well as mitochondrial electron transport using dichlorophenol–indophenol as an electron acceptor. The results of this study show that 6-hydroxymelatonin significantly reduces KCN-induced superoxide anion generation, which is accompanied by a commensurate reduction in lipid peroxidation. Partial reversal of the KCN-induced reduction in mitochondrial electron transport is accompanied by a similar reversal of mitochondrial LDH activity blunted by KCN. It can thus be proposed that 6-hydroxymelatonin is potentially neuroprotective against KCN-induced neurotoxicity.
- Full Text:
- Date Issued: 2003
- Authors: Maharaj, Deepa S , Walker, Roderick B , Glass, Beverley D , Daya, Santylal
- Date: 2003
- Language: English
- Type: Article , text
- Identifier: vital:6405 , http://hdl.handle.net/10962/d1006478
- Description: Both 6-hydroxymelatonin and N-acetyl-N-formyl-5-methoxykynurenamine are photodegradants and enzymatic metabolites of melatonin and are known to retain equipotent activity against potassium cyanide-induced superoxide generation compared to melatonin. It is not clear whether one or both of these metabolites is responsible for this effect. The present study therefore investigates the possible manner in which 6-hydroxymelatonin protects against oxidative stress induced by cyanide in rat brain homogenates. We examined the ability of 6-hydroxymelatonin to scavenge KCN-induced superoxide anion generation as well as lipid peroxidation. In addition, we also examined the effect of this indole on lactate dehydrogenase activity (LDH) as well as mitochondrial electron transport using dichlorophenol–indophenol as an electron acceptor. The results of this study show that 6-hydroxymelatonin significantly reduces KCN-induced superoxide anion generation, which is accompanied by a commensurate reduction in lipid peroxidation. Partial reversal of the KCN-induced reduction in mitochondrial electron transport is accompanied by a similar reversal of mitochondrial LDH activity blunted by KCN. It can thus be proposed that 6-hydroxymelatonin is potentially neuroprotective against KCN-induced neurotoxicity.
- Full Text:
- Date Issued: 2003
Aphid (Sitobion yakini) investigation shows thin-walled sieve tubes in barley (Hordeum vulgare L) to be more functional than thick-walled sieve tubes
- Matsiliza, Balbalwa, Botha, Christiaan E J
- Authors: Matsiliza, Balbalwa , Botha, Christiaan E J
- Date: 2002
- Language: English
- Type: Article
- Identifier: vital:6526 , http://hdl.handle.net/10962/d1005960
- Description: Barley, like most other grasses that have been studied, contains two kinds of sieve tube. The first formed are called thinwalled sieve tubes because of their thin wall compared to the late-formed, and are associated with companion cells. The late-formed are thick-walled sieve tubes, which differentiate next to the metaxylem vessels and lack companion cells. Aphid (Sitobion yakini (Eastop) feeding was studied using light microscopy to determine if they preferentially feed from thin- or thick-walled sieve tubes in the barley leaf. Penetration of the stylets through the leaf epidermis and mesophyll was largely intercellular, becoming partly intercellular and, partly, intracellular inside the vascular bundle. Sixteen of 19 pairs of stylets (84%), and 293 of 317 (92%) stylet tracks terminated at the thin-walled sieve tubes, suggesting that Sitobion yakini feeds preferentially on the thin-walled sieve tubes which seem to be more attractive to the aphid. These thin-walled sieve tubes are thus probably the most functional in terms of phloem loading and transport.
- Full Text:
- Date Issued: 2002
- Authors: Matsiliza, Balbalwa , Botha, Christiaan E J
- Date: 2002
- Language: English
- Type: Article
- Identifier: vital:6526 , http://hdl.handle.net/10962/d1005960
- Description: Barley, like most other grasses that have been studied, contains two kinds of sieve tube. The first formed are called thinwalled sieve tubes because of their thin wall compared to the late-formed, and are associated with companion cells. The late-formed are thick-walled sieve tubes, which differentiate next to the metaxylem vessels and lack companion cells. Aphid (Sitobion yakini (Eastop) feeding was studied using light microscopy to determine if they preferentially feed from thin- or thick-walled sieve tubes in the barley leaf. Penetration of the stylets through the leaf epidermis and mesophyll was largely intercellular, becoming partly intercellular and, partly, intracellular inside the vascular bundle. Sixteen of 19 pairs of stylets (84%), and 293 of 317 (92%) stylet tracks terminated at the thin-walled sieve tubes, suggesting that Sitobion yakini feeds preferentially on the thin-walled sieve tubes which seem to be more attractive to the aphid. These thin-walled sieve tubes are thus probably the most functional in terms of phloem loading and transport.
- Full Text:
- Date Issued: 2002
The great arch of unimagined bridges: integrative play therapy with an abused child
- Authors: McDermott, R
- Date: 2005
- Language: English
- Type: text , Article
- Identifier: vital:6272 , http://hdl.handle.net/10962/d1008272
- Description: This case study describes the early phases of integrative, long-term psychotherapy undertaken with a child subjected to chronic domestic trauma including violence, alcohol abuse, neglect, abandonment, and bereavement resulting from HIV/AIDS. Recent statistics on the prevalence of violent trauma, domestic abuse and HIV/AIDS in South Africa are reviewed, as are principles of trauma intervention that have been established across a range of psychotherapeutic modalities. Following from integrative trauma work undertaken locally, this therapeutic process acknowledges both indigenous and western frameworks of meaning, the latter most heavily informed by principles of analytical psychology. Selected aspects of the therapy are discussed in light of both perspectives, with reference to the child’s process of recovery. This paper seeks to add support to practised and published local work in which a range of possible healing practices, meanings, and experience are taken into account. It is proposed that such integrative efforts contribute towards an evolving African psychotherapy.
- Full Text:
- Date Issued: 2005
- Authors: McDermott, R
- Date: 2005
- Language: English
- Type: text , Article
- Identifier: vital:6272 , http://hdl.handle.net/10962/d1008272
- Description: This case study describes the early phases of integrative, long-term psychotherapy undertaken with a child subjected to chronic domestic trauma including violence, alcohol abuse, neglect, abandonment, and bereavement resulting from HIV/AIDS. Recent statistics on the prevalence of violent trauma, domestic abuse and HIV/AIDS in South Africa are reviewed, as are principles of trauma intervention that have been established across a range of psychotherapeutic modalities. Following from integrative trauma work undertaken locally, this therapeutic process acknowledges both indigenous and western frameworks of meaning, the latter most heavily informed by principles of analytical psychology. Selected aspects of the therapy are discussed in light of both perspectives, with reference to the child’s process of recovery. This paper seeks to add support to practised and published local work in which a range of possible healing practices, meanings, and experience are taken into account. It is proposed that such integrative efforts contribute towards an evolving African psychotherapy.
- Full Text:
- Date Issued: 2005
Development of a stability-indicating high performance liquid chromatographic method for the analysis of topiramate and dissolution rate testing in topiramate tablets
- Mohammadi, Ali, Rezanour, Nasrin, Ansari Dogaheh, M, Walker, Roderick B
- Authors: Mohammadi, Ali , Rezanour, Nasrin , Ansari Dogaheh, M , Walker, Roderick B
- Date: 2010
- Language: English
- Type: text , Article
- Identifier: vital:6412 , http://hdl.handle.net/10962/d1006507
- Description: A stability-indicating high performance liquid chromatographic(HPLC) method was developed and validated for the quantitation and dissolution determination of topiramate in tablet dosage forms. An isocratic separation was achieved using a phenyl column with a flow rate of 1 mL/min using UV detection at 264 nm. Topiramate has low UV absorbtivity and was subjected to derivatization with 9-fluorenylmethyl chloroformate (FMOC-Cl). The mobile phase for the separation consisted of acetonitrile: 50 mM sodium dihydrogen phosphate(NaH2PO4) containing 3 % v/v triethylamine (pH 2.8) in a 48:52 v/v ratio. Topiramate was subjected to oxidation, hydrolysis, photolysis and heat for the purposes of stress testing. Separation was achieved for the parent compound and all the degradation products in an overall analytical run time of approximately 15 min with the parent compound topiramate eluting at approximately 9.2 min. The method was linear over the concentration range of 1-100 μg/mL (r = 0.9996) with limits of quantitation and detection of 1 and 0.3 μg/mL, respectively.
- Full Text:
- Date Issued: 2010
- Authors: Mohammadi, Ali , Rezanour, Nasrin , Ansari Dogaheh, M , Walker, Roderick B
- Date: 2010
- Language: English
- Type: text , Article
- Identifier: vital:6412 , http://hdl.handle.net/10962/d1006507
- Description: A stability-indicating high performance liquid chromatographic(HPLC) method was developed and validated for the quantitation and dissolution determination of topiramate in tablet dosage forms. An isocratic separation was achieved using a phenyl column with a flow rate of 1 mL/min using UV detection at 264 nm. Topiramate has low UV absorbtivity and was subjected to derivatization with 9-fluorenylmethyl chloroformate (FMOC-Cl). The mobile phase for the separation consisted of acetonitrile: 50 mM sodium dihydrogen phosphate(NaH2PO4) containing 3 % v/v triethylamine (pH 2.8) in a 48:52 v/v ratio. Topiramate was subjected to oxidation, hydrolysis, photolysis and heat for the purposes of stress testing. Separation was achieved for the parent compound and all the degradation products in an overall analytical run time of approximately 15 min with the parent compound topiramate eluting at approximately 9.2 min. The method was linear over the concentration range of 1-100 μg/mL (r = 0.9996) with limits of quantitation and detection of 1 and 0.3 μg/mL, respectively.
- Full Text:
- Date Issued: 2010
The relationship between subjective well-being and domain satisfactions in South Africa
- Authors: Moller, Valerie , Saris, W E
- Date: 2001
- Language: English
- Type: Article
- Identifier: vital:7116 , http://hdl.handle.net/10962/d1010749 , http://dx.doi.org/10.1023/A:1010851412273
- Description: This paper examines the relationship between subjective well-being and domain satisfactions. In the past different models have been specified. The most commonly applied model is the bottom-up model in which domain satisfactions affect subjective well-being. The more recent top-down model suggests a reversed relationship. Finally there is the supposition that the correlations between these variables can be spurious due to the effect of personality characteristics. Empirical research has shown that different models are found for different domains and in different countries. Focussing on the effects of the domain satisfactions of finances, housing and social contacts it has been found that subjective well-being is mainly affected by satisfaction with social contacts in Western developed countries and by satisfaction with finances in East European countries. The question we should like to answer in this study is whether a similar pattern obtains for the factors which influence subjective well-being among the different race groups in South Africa. Interestingly, coloured people and Asians did indeed show the expected effects but the groups with the most extreme living conditions did not. Evaluation of life circumstances by black and white South Africans was determined by expectations for the future rather than by current living conditions. This surprising result is discussed in the light of the political situation in South Africa.
- Full Text:
- Date Issued: 2001
- Authors: Moller, Valerie , Saris, W E
- Date: 2001
- Language: English
- Type: Article
- Identifier: vital:7116 , http://hdl.handle.net/10962/d1010749 , http://dx.doi.org/10.1023/A:1010851412273
- Description: This paper examines the relationship between subjective well-being and domain satisfactions. In the past different models have been specified. The most commonly applied model is the bottom-up model in which domain satisfactions affect subjective well-being. The more recent top-down model suggests a reversed relationship. Finally there is the supposition that the correlations between these variables can be spurious due to the effect of personality characteristics. Empirical research has shown that different models are found for different domains and in different countries. Focussing on the effects of the domain satisfactions of finances, housing and social contacts it has been found that subjective well-being is mainly affected by satisfaction with social contacts in Western developed countries and by satisfaction with finances in East European countries. The question we should like to answer in this study is whether a similar pattern obtains for the factors which influence subjective well-being among the different race groups in South Africa. Interestingly, coloured people and Asians did indeed show the expected effects but the groups with the most extreme living conditions did not. Evaluation of life circumstances by black and white South Africans was determined by expectations for the future rather than by current living conditions. This surprising result is discussed in the light of the political situation in South Africa.
- Full Text:
- Date Issued: 2001
Comparative photophysicochemical behavior of nanoconjugates of indium tetracarboxyphenoxy phthalocyanines covalently linked to CdTe/ZnSe/ZnO quantum dots
- Oluwole, David O, Nyokong, Tebello
- Authors: Oluwole, David O , Nyokong, Tebello
- Date: 2015
- Language: English
- Type: text , Article
- Identifier: vital:7294 , http://hdl.handle.net/10962/d1020357 , http://dx.doi.org/10.1016/j.jphotochem.2015.07.009
- Description: This work reports on the photophysicochemical behavior of different nanoconjugates of core/shell/shell (GSH-CdTe/ZnSe/ZnO), core/shell (GSH-CdTe/ZnSe) and core (GSH-CdTe) (quantum dots QDs) with indium tetracarboxyphenoxy phthalocyanines ((OH)InTCPPc) in dimethylsulfoxide. The fluorescence quantum yields (Φf) and lifetimes (τf, in brackets) of QDs ranged from 0.20 (13.9 ns) to 0.42 (25.6 ns). The highest Φf value was obtained for GSH-CdTe/ZnSe/ZnO (4.5) while the least was observed in GSH-CdTe/ZnSe/ZnO (7.6), the numbers in brackets refer to the sizes. For (OH)InTCPPc alone a Φf and τf values of 0.02 and 2.43 ns, respectively were obtained. In the nanoconjugates, pivotal decrease in the Φf and τf of the QDs were observed with increase in the triplet and singlet oxygen quantum yields of (OH)InTCPPc. , Original publication is available at http://dx.doi.org/10.1016/j.jphotochem.2015.07.009
- Full Text: false
- Date Issued: 2015
- Authors: Oluwole, David O , Nyokong, Tebello
- Date: 2015
- Language: English
- Type: text , Article
- Identifier: vital:7294 , http://hdl.handle.net/10962/d1020357 , http://dx.doi.org/10.1016/j.jphotochem.2015.07.009
- Description: This work reports on the photophysicochemical behavior of different nanoconjugates of core/shell/shell (GSH-CdTe/ZnSe/ZnO), core/shell (GSH-CdTe/ZnSe) and core (GSH-CdTe) (quantum dots QDs) with indium tetracarboxyphenoxy phthalocyanines ((OH)InTCPPc) in dimethylsulfoxide. The fluorescence quantum yields (Φf) and lifetimes (τf, in brackets) of QDs ranged from 0.20 (13.9 ns) to 0.42 (25.6 ns). The highest Φf value was obtained for GSH-CdTe/ZnSe/ZnO (4.5) while the least was observed in GSH-CdTe/ZnSe/ZnO (7.6), the numbers in brackets refer to the sizes. For (OH)InTCPPc alone a Φf and τf values of 0.02 and 2.43 ns, respectively were obtained. In the nanoconjugates, pivotal decrease in the Φf and τf of the QDs were observed with increase in the triplet and singlet oxygen quantum yields of (OH)InTCPPc. , Original publication is available at http://dx.doi.org/10.1016/j.jphotochem.2015.07.009
- Full Text: false
- Date Issued: 2015
The diet of a small group of extralimital giraffe
- Parker, Daniel M, Bernard, Ric T F, Colvin, S A
- Authors: Parker, Daniel M , Bernard, Ric T F , Colvin, S A
- Date: 2003
- Language: English
- Type: Article
- Identifier: vital:6950 , http://hdl.handle.net/10962/d1011980
- Description: Giraffe are extralimital in the Eastern Cape Province, South Africa where recent local introductions have persisted despite limited research into their impact on the indigenous flora. The diet of 15 giraffe at the Shamwari Game Reserve was recorded by direct observation during summer (March/April) and winter (July/August) 2001, quantifying diet by frequency of occurrence (individual records scored and expressed as a percentage of the total). Preference indices were also calculated. Habitat use was measured by the number of hours giraffe fed in different habitats. The diet comprised of 14 plant species, the most important species being Rhus longispina (47.9%), Acacia karroo (25.7%) and Euclea undulata (17.6%). Importance of R. longispina, A. karroo and Tarchonanthus camphoratus fluctuated seasonally. Rhus longispina was more important in winter with a corresponding decrease in feeding on A. karroo. Tarchonanthus camphoratus was only consumed during summer. Acacia karroo thickets (previously disturbed areas) were utilized most (summer 12 h; winter 9 h), with alternative habitats utilized more often in winter than in summer. We suggest that the seasonal fluctuation in the importance of R. longispina & A. karroo reflects the deciduous nature of A. karroo.
- Full Text:
- Date Issued: 2003
- Authors: Parker, Daniel M , Bernard, Ric T F , Colvin, S A
- Date: 2003
- Language: English
- Type: Article
- Identifier: vital:6950 , http://hdl.handle.net/10962/d1011980
- Description: Giraffe are extralimital in the Eastern Cape Province, South Africa where recent local introductions have persisted despite limited research into their impact on the indigenous flora. The diet of 15 giraffe at the Shamwari Game Reserve was recorded by direct observation during summer (March/April) and winter (July/August) 2001, quantifying diet by frequency of occurrence (individual records scored and expressed as a percentage of the total). Preference indices were also calculated. Habitat use was measured by the number of hours giraffe fed in different habitats. The diet comprised of 14 plant species, the most important species being Rhus longispina (47.9%), Acacia karroo (25.7%) and Euclea undulata (17.6%). Importance of R. longispina, A. karroo and Tarchonanthus camphoratus fluctuated seasonally. Rhus longispina was more important in winter with a corresponding decrease in feeding on A. karroo. Tarchonanthus camphoratus was only consumed during summer. Acacia karroo thickets (previously disturbed areas) were utilized most (summer 12 h; winter 9 h), with alternative habitats utilized more often in winter than in summer. We suggest that the seasonal fluctuation in the importance of R. longispina & A. karroo reflects the deciduous nature of A. karroo.
- Full Text:
- Date Issued: 2003
Nxele, Ntsikana and the origins of the Xhosa religious reaction
- Authors: Peires, Jeffrey B
- Date: 1979
- Language: English
- Type: Article
- Identifier: vital:6151 , http://hdl.handle.net/10962/d1006830 , https://doi.org/10.1017/S0021853700016716
- Description: The sudden expulsion of the Xhosa across the Fish River in 1811–12 created a practical and conceptual crisis which the traditional political authorities were unable to resolve. Two commoners, Nxele and Ntsikana, emerged in this vacuum, each proposing his own solution to the problems posed by the white irruption. Although these responses were religious responses, they were neither irrational nor incomprehensible. Xhosa religion had long functioned as an instrument for the control of the material world. By incorporating selected Christian concepts with the Xhosa world-view, Nxele and Ntsikana were able to provide the Xhosa with acceptable explanations of past events and prescriptions for future action. Nxele urged resistance and Ntsikana preached submission, but an examination of their personal histories shows that these final conclusions were more the product of exterior pressure than interior revelation. It may be suggested that the future reputations of the two men, like their past actions, will be determined more by the popular mood than by anything they themselves did or said.
- Full Text:
- Date Issued: 1979
- Authors: Peires, Jeffrey B
- Date: 1979
- Language: English
- Type: Article
- Identifier: vital:6151 , http://hdl.handle.net/10962/d1006830 , https://doi.org/10.1017/S0021853700016716
- Description: The sudden expulsion of the Xhosa across the Fish River in 1811–12 created a practical and conceptual crisis which the traditional political authorities were unable to resolve. Two commoners, Nxele and Ntsikana, emerged in this vacuum, each proposing his own solution to the problems posed by the white irruption. Although these responses were religious responses, they were neither irrational nor incomprehensible. Xhosa religion had long functioned as an instrument for the control of the material world. By incorporating selected Christian concepts with the Xhosa world-view, Nxele and Ntsikana were able to provide the Xhosa with acceptable explanations of past events and prescriptions for future action. Nxele urged resistance and Ntsikana preached submission, but an examination of their personal histories shows that these final conclusions were more the product of exterior pressure than interior revelation. It may be suggested that the future reputations of the two men, like their past actions, will be determined more by the popular mood than by anything they themselves did or said.
- Full Text:
- Date Issued: 1979