Photophysicochemical behaviour of anionic indium phthalocyanine when grafted onto AgxAuy and porous silica nanoparticles
- Dube, Edith, Oluwole, David O, Nyokong, Tebello
- Authors: Dube, Edith , Oluwole, David O , Nyokong, Tebello
- Date: 2017
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/188899 , vital:44796 , xlink:href="https://doi.org/10.1016/j.jlumin.2017.05.071"
- Description: This work reports on the synthesis of glutathione functionalised Ag3Au1 (Ag rich alloy, denoted as AgAu) and Ag1Au3 (Au rich alloy – denoted as AuAg) nano alloys as well as aminopropyl triethoxylsilane capped Ag1Au3 doped silica nanoparticles (NPs). The NPs were covalently linked to indium(III) chloride 2,9(10),16(17),23(24)–tetra–(3–carboxyphenoxy)phthalocyanine (1) via amide bond to form 1–AgAuNPs–GSH and 1–AuAgNPs–GSH. The AgAuNPs were also doped into aminopropyl triethoxylsilane (APTES) silica NPs (SiNPs-APTES) followed by linkage to complex 1 to form 1–AgAu-SiNPs–APTES. The photophysicochemical behaviour of complex 1 and its nanoconjugates were investigated. Decrease in the fluorescence quantum yields and lifetimes was observed in the conjugates in comparison to 1 alone. The singlet oxygen quantum yield for 1–AgAuNPs–GSH and 1–AuAgNPs–GSH decreased probably due to the screening effect caused by the NPs, while that of 1–AgAu-SiNPs–APTES increased in dimethylsulfoxide probably due to the permeability of the porous silica matrix to molecular oxygen.
- Full Text:
- Date Issued: 2017
- Authors: Dube, Edith , Oluwole, David O , Nyokong, Tebello
- Date: 2017
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/188899 , vital:44796 , xlink:href="https://doi.org/10.1016/j.jlumin.2017.05.071"
- Description: This work reports on the synthesis of glutathione functionalised Ag3Au1 (Ag rich alloy, denoted as AgAu) and Ag1Au3 (Au rich alloy – denoted as AuAg) nano alloys as well as aminopropyl triethoxylsilane capped Ag1Au3 doped silica nanoparticles (NPs). The NPs were covalently linked to indium(III) chloride 2,9(10),16(17),23(24)–tetra–(3–carboxyphenoxy)phthalocyanine (1) via amide bond to form 1–AgAuNPs–GSH and 1–AuAgNPs–GSH. The AgAuNPs were also doped into aminopropyl triethoxylsilane (APTES) silica NPs (SiNPs-APTES) followed by linkage to complex 1 to form 1–AgAu-SiNPs–APTES. The photophysicochemical behaviour of complex 1 and its nanoconjugates were investigated. Decrease in the fluorescence quantum yields and lifetimes was observed in the conjugates in comparison to 1 alone. The singlet oxygen quantum yield for 1–AgAuNPs–GSH and 1–AuAgNPs–GSH decreased probably due to the screening effect caused by the NPs, while that of 1–AgAu-SiNPs–APTES increased in dimethylsulfoxide probably due to the permeability of the porous silica matrix to molecular oxygen.
- Full Text:
- Date Issued: 2017
Photophysicochemical behaviour of metallophthalocyanines when doped onto silica nanoparticles
- Oluwole, David O, Nyokong, Tebello
- Authors: Oluwole, David O , Nyokong, Tebello
- Date: 2017
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/188518 , vital:44761 , xlink:href="https://doi.org/10.1016/j.dyepig.2016.08.053"
- Description: Aluminum(III) chloride 2,9(10),16(17),23(24)–tetra–(4–tert–butylphenoxy)phthalocyanine (1), zinc(II) 2,9(10),16(17),23(24)–tetra–(4–tert–butylphenoxy)phthalocyanine (2), zinc(II) 1,8(11),15(18),22(25)–tetra–(4–tert–butylphenoxy) phthalocyanine (3) and zinc(II) 2,9(10),16(17),23(24)–tetra–(4–carboxylphenoxy) phthalocyanine (4) were doped onto silica nanoparticles (SiNPs). There were no significant changes in fluorescence quantum yields and lifetimes of the metallophthalocyanines ( MPcs) when doped onto SiNPs. The triplet quantum yields of the MPcs alone range from 0.22 to 0.85 and in the presence of SiNPs the values range from 0.17 to 0.89. We observed a general decrease of triplet quantum yields of phthalocyanines in the conjugates except for 2 where there was an increase. The values were highly affected by aggregation. Complexes 1 and 3 were highly aggregated when doped onto SiNPs, while 2 and 4 did not show much aggregation.
- Full Text:
- Date Issued: 2017
- Authors: Oluwole, David O , Nyokong, Tebello
- Date: 2017
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/188518 , vital:44761 , xlink:href="https://doi.org/10.1016/j.dyepig.2016.08.053"
- Description: Aluminum(III) chloride 2,9(10),16(17),23(24)–tetra–(4–tert–butylphenoxy)phthalocyanine (1), zinc(II) 2,9(10),16(17),23(24)–tetra–(4–tert–butylphenoxy)phthalocyanine (2), zinc(II) 1,8(11),15(18),22(25)–tetra–(4–tert–butylphenoxy) phthalocyanine (3) and zinc(II) 2,9(10),16(17),23(24)–tetra–(4–carboxylphenoxy) phthalocyanine (4) were doped onto silica nanoparticles (SiNPs). There were no significant changes in fluorescence quantum yields and lifetimes of the metallophthalocyanines ( MPcs) when doped onto SiNPs. The triplet quantum yields of the MPcs alone range from 0.22 to 0.85 and in the presence of SiNPs the values range from 0.17 to 0.89. We observed a general decrease of triplet quantum yields of phthalocyanines in the conjugates except for 2 where there was an increase. The values were highly affected by aggregation. Complexes 1 and 3 were highly aggregated when doped onto SiNPs, while 2 and 4 did not show much aggregation.
- Full Text:
- Date Issued: 2017
Photosynthetic and growth responses of C3 and C4 grasses to short- duration sunflecks and resultant consequences for their performance in understory environments
- Authors: Adams, Claire Elizabeth
- Date: 2017
- Subjects: Understory plants -- Effect of light on , Grasses -- Effect of light on -- South Africa , Erharta -- Effect of light on , Brachiara -- Effect of light on
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/5016 , vital:20753
- Description: Low C4 grass species abundance in understory environments is thought to be as a result of their high-light requirements, lack of photosynthetic advantage relative to C3 species in cooler environments, and an inability to adequately utilise sunflecks. This study sets out to investigate this theory, hypothesizing that C3 grass species outperform C4 grass species under the canopy, not as a result of quantum efficiency temperature effects, but as a result of C4 species inability to utilize short-duration sunflecks. Short sunflecks could result in a breakdown in assimilate movement between the mesophyll (MSC) and bundle sheath (BSC) cells. The role of BSC leakiness, stomata and PSII efficiency on the ability of C3 and C4 Alloteropsis semialata to utilize short-duration sunflecks was investigated using gaseous exchange and chlorophyll fluorescence techniques, while the growth of both subspecies under a simulated flecking-light environment tested whether these measured responses translated into effects on growth. As C3 grasses are known to possess higher levels of stomatal conductance in relation to C4 species, results showed that C3 A. semialata was able to utilize short-duration sunflecks as a result of increased stomatal conductance and an ability to induce photosynthesis under various light flecking conditions. In contrast, C4 A. semialata was unable to utilize sunflecks possibly as a result of energetic limitations of the carboxylation mechanism (PSII) and not because of increased bundle sheath leakiness. These photosynthetic responses translated into growth differences when both types were grown in an artificially flecking light environment. The photosynthetic differences noted for C3 and C4 A.semialata were also evident in shade adapted understory grasses; Erharta erecta (C3), Dactylotenium australe (C4) and Brachiaria chusqueoides (C4). As photosynthetic induction was marginally more rapid in all species relative to A. semialata it suggests some degree of adaptation in shade grasses, however the inability of the C4 species to utilise short sunflecks remained. As a result, it was hypothesized that C3 shade adapted E. erecta and C4 B. chusqueoides, co-inhabiting the same forest understory, are able to do so because of differences in light micro-environments associated with each species. However, canopy openness and light profiles determined for theses micro-climates showed no differences and that both species have persisted within a relatively stable understory environment. The coexistence was possible as the understory was supplied with a significant proportion of its daily light in flecks sufficiently long as to not compromise C4 productivity. A survey of 10 species of grasses under various canopy densities and in the open showed a strong negative linear relationship between canopy openness and the rate at which photosynthesis was induced by flecking light, which has not been shown before. This did not result from the phylogenetic relationship between species and could be shown for a single species (E. erecta) growing in a range of light environments. This demonstrates that C4 grasses, despite adaptation, would be limited from sunfleck environments if a significant proportion of the daily light available consists of flecks of short-duration. The generation of such environments may occur as a result of woody thickening and could help explain the observed decline in C4 grasses under these conditions.
- Full Text:
- Date Issued: 2017
- Authors: Adams, Claire Elizabeth
- Date: 2017
- Subjects: Understory plants -- Effect of light on , Grasses -- Effect of light on -- South Africa , Erharta -- Effect of light on , Brachiara -- Effect of light on
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/5016 , vital:20753
- Description: Low C4 grass species abundance in understory environments is thought to be as a result of their high-light requirements, lack of photosynthetic advantage relative to C3 species in cooler environments, and an inability to adequately utilise sunflecks. This study sets out to investigate this theory, hypothesizing that C3 grass species outperform C4 grass species under the canopy, not as a result of quantum efficiency temperature effects, but as a result of C4 species inability to utilize short-duration sunflecks. Short sunflecks could result in a breakdown in assimilate movement between the mesophyll (MSC) and bundle sheath (BSC) cells. The role of BSC leakiness, stomata and PSII efficiency on the ability of C3 and C4 Alloteropsis semialata to utilize short-duration sunflecks was investigated using gaseous exchange and chlorophyll fluorescence techniques, while the growth of both subspecies under a simulated flecking-light environment tested whether these measured responses translated into effects on growth. As C3 grasses are known to possess higher levels of stomatal conductance in relation to C4 species, results showed that C3 A. semialata was able to utilize short-duration sunflecks as a result of increased stomatal conductance and an ability to induce photosynthesis under various light flecking conditions. In contrast, C4 A. semialata was unable to utilize sunflecks possibly as a result of energetic limitations of the carboxylation mechanism (PSII) and not because of increased bundle sheath leakiness. These photosynthetic responses translated into growth differences when both types were grown in an artificially flecking light environment. The photosynthetic differences noted for C3 and C4 A.semialata were also evident in shade adapted understory grasses; Erharta erecta (C3), Dactylotenium australe (C4) and Brachiaria chusqueoides (C4). As photosynthetic induction was marginally more rapid in all species relative to A. semialata it suggests some degree of adaptation in shade grasses, however the inability of the C4 species to utilise short sunflecks remained. As a result, it was hypothesized that C3 shade adapted E. erecta and C4 B. chusqueoides, co-inhabiting the same forest understory, are able to do so because of differences in light micro-environments associated with each species. However, canopy openness and light profiles determined for theses micro-climates showed no differences and that both species have persisted within a relatively stable understory environment. The coexistence was possible as the understory was supplied with a significant proportion of its daily light in flecks sufficiently long as to not compromise C4 productivity. A survey of 10 species of grasses under various canopy densities and in the open showed a strong negative linear relationship between canopy openness and the rate at which photosynthesis was induced by flecking light, which has not been shown before. This did not result from the phylogenetic relationship between species and could be shown for a single species (E. erecta) growing in a range of light environments. This demonstrates that C4 grasses, despite adaptation, would be limited from sunfleck environments if a significant proportion of the daily light available consists of flecks of short-duration. The generation of such environments may occur as a result of woody thickening and could help explain the observed decline in C4 grasses under these conditions.
- Full Text:
- Date Issued: 2017
Phototransferred thermoluminescence in α-Al2O3: C, Mg under 470 nm blue light stimulation
- Kalita, Jitumani M, Chithambo, Makaiko L
- Authors: Kalita, Jitumani M , Chithambo, Makaiko L
- Date: 2017
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/116026 , vital:34290 , https://doi.org/10.1016/j.jlumin.2017.04.059
- Description: Phototransferred thermoluminescence (PTTL) in α-Al2O3:C,Mg under 470 nm blue light has been investigated. Conventional thermoluminescence (TL) measured at 1 °C/s following irradiation to 10 Gy shows the main peak (labelled as III) at 163 °C and six secondary peaks I, II, IV, V, VI and VII at 45, 74, 200, 279, 328, 370 °C respectively. When a sample irradiated to 10 Gy is preheated to 220 °C at 1 °C/s to remove peaks I, II, III and IV and then exposed to 470 nm blue light for 100 s, it is found that three peaks I, II and III are reproduced under phototransfer. Kinetic analysis of the PTTL peaks shows that their kinetic parameters are similar to those of peaks I, II and III from conventional TL. Pulse annealing experiments, intended to study the dependence of PTTL peak intensity on preheating temperature, show that the electron traps corresponding to peaks V, VI and VII act as donor traps whereas the traps corresponding to peaks I, II and III act as acceptor traps. Further, it was found that no PTTL can be generated when all the traps corresponding to peaks I, II…VII are erased by preheating after irradiation. The primary conclusion here is that α-Al2O3:C,Mg does not have any deep traps beyond 400 °C sensitive to 470 nm stimulation or if there are any, their concentration is negligible. The PTTL for any of the PTTL peaks mentioned earlier increases with illumination time to a maximum within 400 s for measurements corresponding to doses between 6 and 15 Gy. The dose response of PTTL peaks II and III is linear within 1–15 Gy. Regarding fading, PTTL peak II fades to background level within 18000 s whereas in the same time, PTTL peak III fades down to 40% of its initial intensity.
- Full Text: false
- Date Issued: 2017
- Authors: Kalita, Jitumani M , Chithambo, Makaiko L
- Date: 2017
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/116026 , vital:34290 , https://doi.org/10.1016/j.jlumin.2017.04.059
- Description: Phototransferred thermoluminescence (PTTL) in α-Al2O3:C,Mg under 470 nm blue light has been investigated. Conventional thermoluminescence (TL) measured at 1 °C/s following irradiation to 10 Gy shows the main peak (labelled as III) at 163 °C and six secondary peaks I, II, IV, V, VI and VII at 45, 74, 200, 279, 328, 370 °C respectively. When a sample irradiated to 10 Gy is preheated to 220 °C at 1 °C/s to remove peaks I, II, III and IV and then exposed to 470 nm blue light for 100 s, it is found that three peaks I, II and III are reproduced under phototransfer. Kinetic analysis of the PTTL peaks shows that their kinetic parameters are similar to those of peaks I, II and III from conventional TL. Pulse annealing experiments, intended to study the dependence of PTTL peak intensity on preheating temperature, show that the electron traps corresponding to peaks V, VI and VII act as donor traps whereas the traps corresponding to peaks I, II and III act as acceptor traps. Further, it was found that no PTTL can be generated when all the traps corresponding to peaks I, II…VII are erased by preheating after irradiation. The primary conclusion here is that α-Al2O3:C,Mg does not have any deep traps beyond 400 °C sensitive to 470 nm stimulation or if there are any, their concentration is negligible. The PTTL for any of the PTTL peaks mentioned earlier increases with illumination time to a maximum within 400 s for measurements corresponding to doses between 6 and 15 Gy. The dose response of PTTL peaks II and III is linear within 1–15 Gy. Regarding fading, PTTL peak II fades to background level within 18000 s whereas in the same time, PTTL peak III fades down to 40% of its initial intensity.
- Full Text: false
- Date Issued: 2017
Phototransferred thermoluminescence of α-Al2O3: C: experimental results and empirical models
- Chithambo, Makaiko L, Seneza, Cleophace, Kalita, Jitumani M
- Authors: Chithambo, Makaiko L , Seneza, Cleophace , Kalita, Jitumani M
- Date: 2017
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/115681 , vital:34215 , https://doi.org/10.1016/j.radmeas.2017.08.009
- Description: The thermoluminescence glow curve of α-Al2O3:C consists of a prominent apparently-single peak and a number of weaker intensity secondary peaks. Phototransferred thermoluminescence (PTTL) from secondary glow peaks in α-Al2O3:C is reported. For completeness and to aid discussion, complementary results for the main peak are included. The problem studied is one of phototransferred thermoluminescence for a system of multiple acceptors and multiple donors. A TL glow curve recorded at 5 °C/s following irradiation to 0.5 Gy shows the main peak (labelled II) at 240 °C and two secondary peaks at 86 °C (peak I) and 360 °C (peak III). Peak I is reproduced under phototransfer after any preheating between 100 and 500 °C. Peak II is also reproduced as a PTTL peak after preheating to any temperature up to 800 °C. For the latter, the duration of preheating matters because if the sample is preheated at 800 °C for say, 6 min, PTTL is obtained but not when this is extended to say, 15 min. No PTTL was observed from peak III at all. A study of the time dependence of the PTTL intensity from peak III, following preheating that removes peaks I and II, shows that its electron trap acts as an acceptor when the duration of illumination to stimulate electrons from deep traps is brief but that when the illumination time is extended, the electron trap for peak III loses some of its trapped electrons to the shallower traps thus acting as a donor trap.
- Full Text: false
- Date Issued: 2017
- Authors: Chithambo, Makaiko L , Seneza, Cleophace , Kalita, Jitumani M
- Date: 2017
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/115681 , vital:34215 , https://doi.org/10.1016/j.radmeas.2017.08.009
- Description: The thermoluminescence glow curve of α-Al2O3:C consists of a prominent apparently-single peak and a number of weaker intensity secondary peaks. Phototransferred thermoluminescence (PTTL) from secondary glow peaks in α-Al2O3:C is reported. For completeness and to aid discussion, complementary results for the main peak are included. The problem studied is one of phototransferred thermoluminescence for a system of multiple acceptors and multiple donors. A TL glow curve recorded at 5 °C/s following irradiation to 0.5 Gy shows the main peak (labelled II) at 240 °C and two secondary peaks at 86 °C (peak I) and 360 °C (peak III). Peak I is reproduced under phototransfer after any preheating between 100 and 500 °C. Peak II is also reproduced as a PTTL peak after preheating to any temperature up to 800 °C. For the latter, the duration of preheating matters because if the sample is preheated at 800 °C for say, 6 min, PTTL is obtained but not when this is extended to say, 15 min. No PTTL was observed from peak III at all. A study of the time dependence of the PTTL intensity from peak III, following preheating that removes peaks I and II, shows that its electron trap acts as an acceptor when the duration of illumination to stimulate electrons from deep traps is brief but that when the illumination time is extended, the electron trap for peak III loses some of its trapped electrons to the shallower traps thus acting as a donor trap.
- Full Text: false
- Date Issued: 2017
Phylogeny and phylogeography of dominant South African surf diatoms
- Authors: Du Preez, Debbie Patricia
- Date: 2017
- Subjects: Phylogeography -- South Africa , Diatoms -- South Africa Phylogeny -- Molecular aspects DNA -- Analysis
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/29794 , vital:30778
- Description: Genetic studies of diatoms are lagging behind those on other organisms. The reasons for this are, among others, that many species are difficult to culture (some surf diatoms in particular), single cells contain only a small amount of DNA, and selection of single cells from environmental samples is difficult. Globally, there are only a few species of surf diatom: Anaulus australis Drebes et Schultz, Asterionellopsis glacialis (Castracane) Round, Asterionellopsis socialis (Lewin & Norris) Crawford & Gardner, Attheya armata (West) Crawford, Aulacodiscus petersii Ehrenberg, Aulacodiscus johnsonii Arnott, Aulacodiscus kittonii Arnott ex Ralfs and Aulacodiscus africanus Cottam. These species occur exclusively in the surf zone with the exception of A. glacialis, which is also found in coastal and oceanic waters. The overall aim of this project was to investigate the phylogeny or the phylogeography of the two dominant South African surf diatoms. In order to do this, it was necessary to develop methods for extracting DNA from environmental surf diatom patch samples. This method was then used in the investigation into the phylogeography of Anaulus australis along the South African coastal zone. Due to other recent work into diatom phylogeny and phylogeography there was also the opportunity to compare the genetics of the South African surf diatom Asterionellopsis found at Sundays River Beach to localities recently sampled and sequenced around the globe in order to identify the species found in South Africa. The direct method was successful for DNA extraction from Anaulus australis cells preserved using either isopropanol, ethanol or glutaraldehyde (provided the samples were not older than two years), but not formalin. Extraction of DNA from Asterionellopsis glacialis s.l. cells was successful with the direct method for ethanol-preserved samples, but the extraction from Attheya armata cells required some modifications be added to the method. Sequencing of the ITS region of Anaulus australis cells from along the southern coast of South Africa indicated connectivity between the various populations rather than the expected isolation of populations in the surf zones of the log-spiral bays. Comparison of the ITS and RbcL regions of the species of Asterionellopsis found at the Sundays River Beach indicated that it is Asterionellopsis lenisilicea which is a species only ii recorded from Canada to date and which has only recently been discovered and recognised as a new species within the genus. This genetic identification was supported by morphological measurements of frustules.
- Full Text:
- Date Issued: 2017
- Authors: Du Preez, Debbie Patricia
- Date: 2017
- Subjects: Phylogeography -- South Africa , Diatoms -- South Africa Phylogeny -- Molecular aspects DNA -- Analysis
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/29794 , vital:30778
- Description: Genetic studies of diatoms are lagging behind those on other organisms. The reasons for this are, among others, that many species are difficult to culture (some surf diatoms in particular), single cells contain only a small amount of DNA, and selection of single cells from environmental samples is difficult. Globally, there are only a few species of surf diatom: Anaulus australis Drebes et Schultz, Asterionellopsis glacialis (Castracane) Round, Asterionellopsis socialis (Lewin & Norris) Crawford & Gardner, Attheya armata (West) Crawford, Aulacodiscus petersii Ehrenberg, Aulacodiscus johnsonii Arnott, Aulacodiscus kittonii Arnott ex Ralfs and Aulacodiscus africanus Cottam. These species occur exclusively in the surf zone with the exception of A. glacialis, which is also found in coastal and oceanic waters. The overall aim of this project was to investigate the phylogeny or the phylogeography of the two dominant South African surf diatoms. In order to do this, it was necessary to develop methods for extracting DNA from environmental surf diatom patch samples. This method was then used in the investigation into the phylogeography of Anaulus australis along the South African coastal zone. Due to other recent work into diatom phylogeny and phylogeography there was also the opportunity to compare the genetics of the South African surf diatom Asterionellopsis found at Sundays River Beach to localities recently sampled and sequenced around the globe in order to identify the species found in South Africa. The direct method was successful for DNA extraction from Anaulus australis cells preserved using either isopropanol, ethanol or glutaraldehyde (provided the samples were not older than two years), but not formalin. Extraction of DNA from Asterionellopsis glacialis s.l. cells was successful with the direct method for ethanol-preserved samples, but the extraction from Attheya armata cells required some modifications be added to the method. Sequencing of the ITS region of Anaulus australis cells from along the southern coast of South Africa indicated connectivity between the various populations rather than the expected isolation of populations in the surf zones of the log-spiral bays. Comparison of the ITS and RbcL regions of the species of Asterionellopsis found at the Sundays River Beach indicated that it is Asterionellopsis lenisilicea which is a species only ii recorded from Canada to date and which has only recently been discovered and recognised as a new species within the genus. This genetic identification was supported by morphological measurements of frustules.
- Full Text:
- Date Issued: 2017
Phylogeny of the Sepia officinalis species complex in the eastern Atlantic extends the known distribution of Sepia vermiculata across the Benguela upwelling region
- Healey, Amy J E, McKeown, Niall J, Potts, Warren M, de Beer, Chénelle L, Sauer, Warwick H H, Shaw, Paul W
- Authors: Healey, Amy J E , McKeown, Niall J , Potts, Warren M , de Beer, Chénelle L , Sauer, Warwick H H , Shaw, Paul W
- Date: 2017
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/125631 , vital:35802 , https://doi.10.2989/1814232X.2017.1371076
- Description: Accurate species identification and biogeographic characterisation are fundamental for appropriate management of expanding cephalopod fisheries. This study addresses this topic within the common cuttlefish Sepia officinalis species complex (S. officinalis, S. hierredda and S. vermiculata), with an emphasis on occurrence in African waters. Tissue samples from the currently presumed distributions of S. vermiculata and S. hierredda (from South Africa and Ghana/Angola, respectively) were sequenced for the cytochrome c oxidase subunit I (COI) and the cytochrome b (cytb) genes of the mitochondrial genome and then compared to existing S. officinalis sequences. Three highly divergent and reciprocally monophyletic clades, corresponding to S. officinalis, S. hierredda and S. vermiculata, were resolved, representing the first molecular confirmation of the distinct species status of S. hierredda and S. vermiculata. The sequences also revealed that, contrary to expectations based on presently published information, all samples from southern Angola were S. vermiculata. These results indicate that the range of S. vermiculata extends beyond the currently described northern limit and that S. hierredda and S. vermiculata may be indiscriminately harvested in Angolan waters. Finer-scale patterns within S. vermiculata phylogeography also indicate that the Benguela Current System and/or other environmental factors serve to isolate northern and southern stocks.
- Full Text:
- Date Issued: 2017
- Authors: Healey, Amy J E , McKeown, Niall J , Potts, Warren M , de Beer, Chénelle L , Sauer, Warwick H H , Shaw, Paul W
- Date: 2017
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/125631 , vital:35802 , https://doi.10.2989/1814232X.2017.1371076
- Description: Accurate species identification and biogeographic characterisation are fundamental for appropriate management of expanding cephalopod fisheries. This study addresses this topic within the common cuttlefish Sepia officinalis species complex (S. officinalis, S. hierredda and S. vermiculata), with an emphasis on occurrence in African waters. Tissue samples from the currently presumed distributions of S. vermiculata and S. hierredda (from South Africa and Ghana/Angola, respectively) were sequenced for the cytochrome c oxidase subunit I (COI) and the cytochrome b (cytb) genes of the mitochondrial genome and then compared to existing S. officinalis sequences. Three highly divergent and reciprocally monophyletic clades, corresponding to S. officinalis, S. hierredda and S. vermiculata, were resolved, representing the first molecular confirmation of the distinct species status of S. hierredda and S. vermiculata. The sequences also revealed that, contrary to expectations based on presently published information, all samples from southern Angola were S. vermiculata. These results indicate that the range of S. vermiculata extends beyond the currently described northern limit and that S. hierredda and S. vermiculata may be indiscriminately harvested in Angolan waters. Finer-scale patterns within S. vermiculata phylogeography also indicate that the Benguela Current System and/or other environmental factors serve to isolate northern and southern stocks.
- Full Text:
- Date Issued: 2017
Physical organic studies of substituted norbornyl systems: aspects of mechanisms and chirality
- Authors: Singh, Alicia
- Date: 2017
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/50558 , vital:25999
- Description: Fenchone and camphor are essential natural products that are available optically pure and contribute to the chiral pool in asymmetric synthesis. Further, they are both derivatives of norbornane, a structure that undergoes a remarkable diversity of rearrangements in acidic conditions. This work explores two aspects of the camphor/fenchone derived systems. Firstly an attempt to clarify rearrangement mechanisms on a camphor system successfully via deuterium labelling and unsuccessfully via derivatization of fenchone (with rearrangement) to produce other 13C-labelled camphor substitutions, has resulted in confirmation of a theoretically proposed, highly concerted Wagner-Meerwein, 6,2 - hydride shift, Wagner-Meerwein rearrangement in competition with an associated 2,3-methide shift. Kinetics and activation parameters for many steps have been resolved in this rearrangement of the deuterium labelled camphor-derived tosylate system to two pairs of isotopomers. Further, the kinetics and formation of an unexpected pair of dimers encountered during the scheme for 13C labelling are investigated in detail. These dimers (forming during the initial stages of the synthetic scheme) are unusual in that they are not expected rotamers of each other, but diastereomers resulting from chirality of a sulfur atom in a sulfite moiety. A feasible mechanism of formation that matches the kinetics has been proposed in this unexpectedly complex system, and thermodynamic parameters have been determined. The second aspect of substituted norbornyl systems pertains to their chirality, and the influence of this chirality on reaction mixtures, with an aim to identify novel chiral micellar catalysts for use in heterogeneous reaction mixtures. Headway has been made towards the synthesis of the appropriate surfactants to be used in the construction of these micelles, but extensive molecular dynamics simulations have illustrated the feasibility of forming the stable chiral micelles in a dual-solvent system, and detail precisely the influence of chirality on surrounding media. These studies add important physical organic data as well as show the immense possibilities pertaining to substituted norbornane systems.
- Full Text:
- Date Issued: 2017
- Authors: Singh, Alicia
- Date: 2017
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/50558 , vital:25999
- Description: Fenchone and camphor are essential natural products that are available optically pure and contribute to the chiral pool in asymmetric synthesis. Further, they are both derivatives of norbornane, a structure that undergoes a remarkable diversity of rearrangements in acidic conditions. This work explores two aspects of the camphor/fenchone derived systems. Firstly an attempt to clarify rearrangement mechanisms on a camphor system successfully via deuterium labelling and unsuccessfully via derivatization of fenchone (with rearrangement) to produce other 13C-labelled camphor substitutions, has resulted in confirmation of a theoretically proposed, highly concerted Wagner-Meerwein, 6,2 - hydride shift, Wagner-Meerwein rearrangement in competition with an associated 2,3-methide shift. Kinetics and activation parameters for many steps have been resolved in this rearrangement of the deuterium labelled camphor-derived tosylate system to two pairs of isotopomers. Further, the kinetics and formation of an unexpected pair of dimers encountered during the scheme for 13C labelling are investigated in detail. These dimers (forming during the initial stages of the synthetic scheme) are unusual in that they are not expected rotamers of each other, but diastereomers resulting from chirality of a sulfur atom in a sulfite moiety. A feasible mechanism of formation that matches the kinetics has been proposed in this unexpectedly complex system, and thermodynamic parameters have been determined. The second aspect of substituted norbornyl systems pertains to their chirality, and the influence of this chirality on reaction mixtures, with an aim to identify novel chiral micellar catalysts for use in heterogeneous reaction mixtures. Headway has been made towards the synthesis of the appropriate surfactants to be used in the construction of these micelles, but extensive molecular dynamics simulations have illustrated the feasibility of forming the stable chiral micelles in a dual-solvent system, and detail precisely the influence of chirality on surrounding media. These studies add important physical organic data as well as show the immense possibilities pertaining to substituted norbornane systems.
- Full Text:
- Date Issued: 2017
Physiochemical and heavy metals fingerprints of the final effluents of Adelaide and Seymour wastewater treatment facilities in the Eastern Cape, South Africa
- Authors: Mutukwa, Dorcas
- Date: 2017
- Subjects: Water -- Purification Effluent quality -- Testing
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10353/8089 , vital:31520
- Description: Wastewater contains pathogens, heavy metals, nutrients, organic matter and other toxic chemicals and when discharged into the environment without proper treatment, it may cause adverse health problems and environment degradation. There have been reports in the Eastern Cape Province, South Africa of inadequate treated wastewater effluents being discharged into freshwater environments. This study reports on the physicochemical and heavy metals qualities for two wastewater treatment facilities in the Eastern Cape, South Africa over a six-month sampling period (September 2015 to February 2016). Wastewater effluent samples were collected from the influents, final effluents and receiving waterbodies as well as sludge samples in replicates. The physicochemical parameters were analysed using standard methods (APHA, 2012). The acid digested heavy metals samples were analysed using Atomic Absorption Spectrophotometer (iCE 3500 Thermo Fisher Spectrometer). The concentrations were compared to recommended limits used in South Africa and World Health Organisation (WHO). Physicochemical qualities assessed at Adelaide wastewater treatment plant ranged as follows: temperature (21.6 - 30.5 oC), turbidity (2.1 – 71.3 NTU), electrical conductivity (EC) (743.0 – 898.3 μ/Scm) and dissolved oxygen (DO) (2.11 – 3.50 mg/L) while the ranges of the parameter assessed at Seymour wastewater treatment plant ranged as follows: chemical dissolved oxygen (COD) (41.7 – 115.3 mg/L), EC (628 and 797.7 μ/Scm) and nitrates (4.6 – 11.0 mg/L. The heavy metals concentration for the final effluents at Adelaide wastewater treatment plant ranged as follows: Cd (0 – 0.002 mg/L), Cu (0 – 0.096 mg/L) and Fe (0 – 0.498 mg/L). Cu concentrations in sludge at Seymour wastewater treatment plant ranged between 83.82 and 132.07 mg/L. Reduction efficiencies of Adelaide in removing chlorides and sulphates were 33 and 36 percent respectively. Findings of study revealed negative impacts of inadequately treated effluents on receiving waterbodies and this puts communities which rely on the water as immediate source of fresh water for domestic purposes at health risk.
- Full Text:
- Date Issued: 2017
- Authors: Mutukwa, Dorcas
- Date: 2017
- Subjects: Water -- Purification Effluent quality -- Testing
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10353/8089 , vital:31520
- Description: Wastewater contains pathogens, heavy metals, nutrients, organic matter and other toxic chemicals and when discharged into the environment without proper treatment, it may cause adverse health problems and environment degradation. There have been reports in the Eastern Cape Province, South Africa of inadequate treated wastewater effluents being discharged into freshwater environments. This study reports on the physicochemical and heavy metals qualities for two wastewater treatment facilities in the Eastern Cape, South Africa over a six-month sampling period (September 2015 to February 2016). Wastewater effluent samples were collected from the influents, final effluents and receiving waterbodies as well as sludge samples in replicates. The physicochemical parameters were analysed using standard methods (APHA, 2012). The acid digested heavy metals samples were analysed using Atomic Absorption Spectrophotometer (iCE 3500 Thermo Fisher Spectrometer). The concentrations were compared to recommended limits used in South Africa and World Health Organisation (WHO). Physicochemical qualities assessed at Adelaide wastewater treatment plant ranged as follows: temperature (21.6 - 30.5 oC), turbidity (2.1 – 71.3 NTU), electrical conductivity (EC) (743.0 – 898.3 μ/Scm) and dissolved oxygen (DO) (2.11 – 3.50 mg/L) while the ranges of the parameter assessed at Seymour wastewater treatment plant ranged as follows: chemical dissolved oxygen (COD) (41.7 – 115.3 mg/L), EC (628 and 797.7 μ/Scm) and nitrates (4.6 – 11.0 mg/L. The heavy metals concentration for the final effluents at Adelaide wastewater treatment plant ranged as follows: Cd (0 – 0.002 mg/L), Cu (0 – 0.096 mg/L) and Fe (0 – 0.498 mg/L). Cu concentrations in sludge at Seymour wastewater treatment plant ranged between 83.82 and 132.07 mg/L. Reduction efficiencies of Adelaide in removing chlorides and sulphates were 33 and 36 percent respectively. Findings of study revealed negative impacts of inadequately treated effluents on receiving waterbodies and this puts communities which rely on the water as immediate source of fresh water for domestic purposes at health risk.
- Full Text:
- Date Issued: 2017
Physiochemical, fatty acids, lipid oxidation, sensory characteristics and consumer acceptance of warthog cabanossi produced with pork backfat and fat-tailed sheep backfat
- Authors: Mahachi, Leo Nyikadzino
- Date: 2017
- Subjects: Fatty acids Lipids -- Oxidation
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10353/6259 , vital:29530
- Description: The objective of this study was to determine the effect of different fat inclusion levels and fat types on the physical and chemical attributes, lipid oxidation, fatty acid composition and sensory characteristics of warthog cabanossi. To achieve this, three types of cabanossi with different pork backfat levels (10 percent, 20 percent and 30 percent) were produced for the first experiment. The results from the study showed that different inclusion levels of pork backfat had an influence (P ≤ 0.05) on the physicochemical and fatty acid composition of warthog cabanossi but did not influence lipid oxidation (P > 0.05). The highest (P ≤0.05) pH, weight and moisture decline was observed in the 10 percent pork backfat cabanossi compared to the 20 percent and 30 percent treatments. However, no differences (P > 0.05) in the water activity of the product were observed. As expected total fat was lower in the 10 percent fat treatment and increased concomitantly. Similarly, protein, ash and salt were higher in the 10 percent fat cabanossi and decreased concomitantly. Differences in the fatty acid composition were observed between treatments. Furthermore, backfat level affected the sensory attributes and consumer acceptance of the cabanossi. Ten percent backfat cabanossi was scored higher (P ≤0.05) for most sensory attributes. Consequently, it was observed that the consumer panel preferred and scored the 10 percent fat cabanossi higher with regards to appearance and taste. In the second experiment, two cabanossi treatments of different fat types (pork backfat and fat-tailed sheep backfat) were produced. The weight loss, moisture content, pH, water activity and salt content did not differ (P > 0.05) between the two cabanossi products. However, there were differences (P ≤0.05) in the protein, fat and ash contents; where protein and ash were higher in the pork backfat cabanossi whilst fat was higher in the sheep backfat cabanossi. Thiobarbituric reactive substances (TBARS) were similar (P > 0.05) between the two fat types cabanossi which could be explained by similar fatty acid profiles being reported for the two cabanossi although the n-6:n-3 ratio was higher (P ≤0.05) in sheep backfat cabanossi. Results from the descriptive sensory analysis showed two distinct products (P ≤0.01) where pork backfat cabanossi scored higher for most attributes. However, the lower scores for sheep backfat cabanossi were within an acceptable range. Sheep backfat cabanossi were also scored for unique attributes that were not detected in the pork backfat cabanossi. This study concluded that fat-tailed sheep backfat can be used to produce an unique cabanossi product of acceptable quality.
- Full Text:
- Date Issued: 2017
- Authors: Mahachi, Leo Nyikadzino
- Date: 2017
- Subjects: Fatty acids Lipids -- Oxidation
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10353/6259 , vital:29530
- Description: The objective of this study was to determine the effect of different fat inclusion levels and fat types on the physical and chemical attributes, lipid oxidation, fatty acid composition and sensory characteristics of warthog cabanossi. To achieve this, three types of cabanossi with different pork backfat levels (10 percent, 20 percent and 30 percent) were produced for the first experiment. The results from the study showed that different inclusion levels of pork backfat had an influence (P ≤ 0.05) on the physicochemical and fatty acid composition of warthog cabanossi but did not influence lipid oxidation (P > 0.05). The highest (P ≤0.05) pH, weight and moisture decline was observed in the 10 percent pork backfat cabanossi compared to the 20 percent and 30 percent treatments. However, no differences (P > 0.05) in the water activity of the product were observed. As expected total fat was lower in the 10 percent fat treatment and increased concomitantly. Similarly, protein, ash and salt were higher in the 10 percent fat cabanossi and decreased concomitantly. Differences in the fatty acid composition were observed between treatments. Furthermore, backfat level affected the sensory attributes and consumer acceptance of the cabanossi. Ten percent backfat cabanossi was scored higher (P ≤0.05) for most sensory attributes. Consequently, it was observed that the consumer panel preferred and scored the 10 percent fat cabanossi higher with regards to appearance and taste. In the second experiment, two cabanossi treatments of different fat types (pork backfat and fat-tailed sheep backfat) were produced. The weight loss, moisture content, pH, water activity and salt content did not differ (P > 0.05) between the two cabanossi products. However, there were differences (P ≤0.05) in the protein, fat and ash contents; where protein and ash were higher in the pork backfat cabanossi whilst fat was higher in the sheep backfat cabanossi. Thiobarbituric reactive substances (TBARS) were similar (P > 0.05) between the two fat types cabanossi which could be explained by similar fatty acid profiles being reported for the two cabanossi although the n-6:n-3 ratio was higher (P ≤0.05) in sheep backfat cabanossi. Results from the descriptive sensory analysis showed two distinct products (P ≤0.01) where pork backfat cabanossi scored higher for most attributes. However, the lower scores for sheep backfat cabanossi were within an acceptable range. Sheep backfat cabanossi were also scored for unique attributes that were not detected in the pork backfat cabanossi. This study concluded that fat-tailed sheep backfat can be used to produce an unique cabanossi product of acceptable quality.
- Full Text:
- Date Issued: 2017
Physiology and Spatio-temporal Relations of Nutrient Acquisition by Roots and Root Symbionts
- Valentine, Alex J, Kleinert, Aleysia, Thuynsma, Rochelle, Chimphango, Samson, Dames, Joanna F, Benedito, V A
- Authors: Valentine, Alex J , Kleinert, Aleysia , Thuynsma, Rochelle , Chimphango, Samson , Dames, Joanna F , Benedito, V A
- Date: 2017
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/448652 , vital:74749 , https://doi.org/10.1007/124_2016_11
- Description: Among the various functions of roots, nutrient acquisition (via soil uptake or through symbiotic relationships) is one of the most essential for land plants. Soil from natural and agricultural ecosystems may impede plant nutrient acquisition, by many factors such as mineral availabilities either in excess or deficient supply, depletion of organic matter, extreme variations in water supply, and many other physical and chemical features. In order to survive, plants need to undergo developmental and physiological mechanisms to cope with these extreme soil situations. Here we review how plants control nutrient acquisition by dynamically changing root architecture for improved soil space exploration, as well as altering cellular-level function for enhanced nutrient uptake, via apoplastic acidification, exudation of enzymes and metabolites (organic acids, secondary metabolites) and constantly changing the composition of transporters at the plasma membrane. These changes start with environmental cues which induce cell signaling and involve hormones and coordinated regulatory genes networks that drive the root’s developmental plasticity as well as the cell’s biochemical dynamics. Mutualistic root symbioses, such as mycorrhizae and rhizobial-induced nodulation, are also important to provide essential nutrients to the plant, which are tightly regulated in order to only occur at plant’s benefit. We also explore molecular mechanisms which roots have evolved to cope with nutritional, as well as other soil stresses, such as aluminium toxicity and heavy metals. Overall, understanding root dynamics under several environmental variables at different perspectives, from root architecture to biochemistry to genetic levels will allow us to better explore the spatial and temporal relations of roots with their mineral nutrient environment.
- Full Text:
- Date Issued: 2017
- Authors: Valentine, Alex J , Kleinert, Aleysia , Thuynsma, Rochelle , Chimphango, Samson , Dames, Joanna F , Benedito, V A
- Date: 2017
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/448652 , vital:74749 , https://doi.org/10.1007/124_2016_11
- Description: Among the various functions of roots, nutrient acquisition (via soil uptake or through symbiotic relationships) is one of the most essential for land plants. Soil from natural and agricultural ecosystems may impede plant nutrient acquisition, by many factors such as mineral availabilities either in excess or deficient supply, depletion of organic matter, extreme variations in water supply, and many other physical and chemical features. In order to survive, plants need to undergo developmental and physiological mechanisms to cope with these extreme soil situations. Here we review how plants control nutrient acquisition by dynamically changing root architecture for improved soil space exploration, as well as altering cellular-level function for enhanced nutrient uptake, via apoplastic acidification, exudation of enzymes and metabolites (organic acids, secondary metabolites) and constantly changing the composition of transporters at the plasma membrane. These changes start with environmental cues which induce cell signaling and involve hormones and coordinated regulatory genes networks that drive the root’s developmental plasticity as well as the cell’s biochemical dynamics. Mutualistic root symbioses, such as mycorrhizae and rhizobial-induced nodulation, are also important to provide essential nutrients to the plant, which are tightly regulated in order to only occur at plant’s benefit. We also explore molecular mechanisms which roots have evolved to cope with nutritional, as well as other soil stresses, such as aluminium toxicity and heavy metals. Overall, understanding root dynamics under several environmental variables at different perspectives, from root architecture to biochemistry to genetic levels will allow us to better explore the spatial and temporal relations of roots with their mineral nutrient environment.
- Full Text:
- Date Issued: 2017
Plagiarism in master of education studies at selected East African Universities
- Authors: Ramadhan, Zainabu
- Date: 2017
- Subjects: Plagiarism -- Africa , Imitation in literature Education, Higher -- Moral and ethical aspects College students -- Africa
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: http://hdl.handle.net/10948/20581 , vital:29324
- Description: Plagiarism is a form of academic misconduct and is a problematic phenomenon which affects academia globally. Even though the origins of the concept of plagiarism can be traced back throughout history, the term has come to carry many varying implications. This may affect the ways in which plagiarism is understood, detected and prosecuted by the parties it involves, such as students, academics and in policies. Despite its origin in Western tradition, this form of academic malpractice is prominent in African universities. In its most basic definition as theft of intellectual property, plagiarism is intertwined intricately with ownership of knowledge, which is culturally specific. This study situates itself within the context of three African universities, namely Moi University (Kenya), Makerere University (Uganda) and the University of Dar es Salaam (Tanzania), and aims to explore anti-plagiarism strategies implemented at these institutions. More specifically, this study focuses on Master of Education students’ perceptions of plagiarism, the supervisors’ role in preventing and detecting such malpractice and the institutional disciplinary practices in place. This study analyses the possible reasons for the continuous occurrence of plagiarism at these institutions and aims to explore the potential of further strategies to prevent the various forms of malpractice. This research is a qualitative study and uses the constructivist paradigm. The research design is a multiple case study because the data collected originates from the contexts of the three selected universities. The data generation was conducted through triangulation of personal interviews with the students, lecturers and policy-makers as well as through focus group discussions with students and document analysis. Three methods of sampling were employed. The student participants were selected through convenient sampling, the supervisors were chosen through purposive sampling and snowballing was used to identify policy-makers. The data analysis was conducted thematically. In discussing the methodology and findings, Vygotsky’s Socio-cultural theory (1978) is employed. The introductory chapter provides an overview of the complexities of plagiarism and problematizes its implications. Chapter two outlines the relevant literature and contextualizes the research topic. The third chapter introduces the methodology. Chapter four presents the data collected. Thereafter, chapter five focuses on the interpretation and the discussion of the data. The last chapter draws conclusions in relation to the research questions and suggests areas for further research.
- Full Text:
- Date Issued: 2017
- Authors: Ramadhan, Zainabu
- Date: 2017
- Subjects: Plagiarism -- Africa , Imitation in literature Education, Higher -- Moral and ethical aspects College students -- Africa
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: http://hdl.handle.net/10948/20581 , vital:29324
- Description: Plagiarism is a form of academic misconduct and is a problematic phenomenon which affects academia globally. Even though the origins of the concept of plagiarism can be traced back throughout history, the term has come to carry many varying implications. This may affect the ways in which plagiarism is understood, detected and prosecuted by the parties it involves, such as students, academics and in policies. Despite its origin in Western tradition, this form of academic malpractice is prominent in African universities. In its most basic definition as theft of intellectual property, plagiarism is intertwined intricately with ownership of knowledge, which is culturally specific. This study situates itself within the context of three African universities, namely Moi University (Kenya), Makerere University (Uganda) and the University of Dar es Salaam (Tanzania), and aims to explore anti-plagiarism strategies implemented at these institutions. More specifically, this study focuses on Master of Education students’ perceptions of plagiarism, the supervisors’ role in preventing and detecting such malpractice and the institutional disciplinary practices in place. This study analyses the possible reasons for the continuous occurrence of plagiarism at these institutions and aims to explore the potential of further strategies to prevent the various forms of malpractice. This research is a qualitative study and uses the constructivist paradigm. The research design is a multiple case study because the data collected originates from the contexts of the three selected universities. The data generation was conducted through triangulation of personal interviews with the students, lecturers and policy-makers as well as through focus group discussions with students and document analysis. Three methods of sampling were employed. The student participants were selected through convenient sampling, the supervisors were chosen through purposive sampling and snowballing was used to identify policy-makers. The data analysis was conducted thematically. In discussing the methodology and findings, Vygotsky’s Socio-cultural theory (1978) is employed. The introductory chapter provides an overview of the complexities of plagiarism and problematizes its implications. Chapter two outlines the relevant literature and contextualizes the research topic. The third chapter introduces the methodology. Chapter four presents the data collected. Thereafter, chapter five focuses on the interpretation and the discussion of the data. The last chapter draws conclusions in relation to the research questions and suggests areas for further research.
- Full Text:
- Date Issued: 2017
Plasma gasification for converting municipal solid waste to energy
- Authors: Serage, Noah Magonagone
- Date: 2017
- Subjects: Recycling (Waste, etc.) -- South Africa Refuse and refuse disposal -- South Africa , Energy conversion -- South Africa
- Language: English
- Type: Thesis , Masters , MBA
- Identifier: http://hdl.handle.net/10948/20266 , vital:29166
- Description: In South Africa most of the municipal solid waste is currently removed and taken to land fill sites for engraving. A very small percentage of this is recycled due to lack of exploration of alternative means of further processing. In 2011 approximately 108 million tonnes of waste, mostly being general waste was generated in South Africa. Ninety eight (98) million tonnes of this waste was disposed of at landfill sites (The Department of Environmental Affairs [DEA], 2012). Environmental engineers are finding municipal solid waste management to be a challenge, similarly do the city planners and local administration. The main reason being the difficulty brought about by the complexity in composition of the waste material, no availability of waste minimization technologies and the scarcity of land for landfill sites and their environmental impact (Lal & Singh, 2012). Anyaegbunam (2013) recommend that there is a disposal technique that can convert most of the landfill waste at reduced amount of money to what is being paid on other disposal techniques nowadays, regardless of its form or composition and produce an excess of clean energy, and that technique is called Plasma Gasification which carries a high capability of being economically efficient. According to Young (2010), plasma arc Gasification is a high-temperature pyrolysis process whereby the organics of waste solids (carbon-based materials) are converted into syngas. The syngas can also be sent to gas turbines or reciprocating engines to produce electricity. Few of these plants exist in the world, however there is none in South Africa due to municipal budgetary constraints and lack of evidence for return on investment. Gasification can be described as a thermo-chemical process wherein carbonaceous or carbon-rich feed stocks, for instance tree trimmings or biomass, coal, and petro-coke are transformed into a complex gas containing hydrogen and carbon monoxide (and smaller quantities of carbon dioxide and other trace gases) under high pressure, oxygen exhausted, strong heat and/or steam environments (SRS Energy Solutions, 2016) The problem of electricity shortages continues to increase and communities are unable to cope with the continuous rising electricity bills. It is forecast that electricity demand will grow by approximately 85% and thereby reaching 31 700TWH (terawatt hours) in the year 2035. This growth rate is anticipated at an annual rate of 2.4% of which the economic and population growth will be the driving force, while on the other hand the daily increase of waste at landfill sites poses many problems with regards to the lifespan of the landfill in case green technological disposal processes are not introduced.
- Full Text:
- Date Issued: 2017
- Authors: Serage, Noah Magonagone
- Date: 2017
- Subjects: Recycling (Waste, etc.) -- South Africa Refuse and refuse disposal -- South Africa , Energy conversion -- South Africa
- Language: English
- Type: Thesis , Masters , MBA
- Identifier: http://hdl.handle.net/10948/20266 , vital:29166
- Description: In South Africa most of the municipal solid waste is currently removed and taken to land fill sites for engraving. A very small percentage of this is recycled due to lack of exploration of alternative means of further processing. In 2011 approximately 108 million tonnes of waste, mostly being general waste was generated in South Africa. Ninety eight (98) million tonnes of this waste was disposed of at landfill sites (The Department of Environmental Affairs [DEA], 2012). Environmental engineers are finding municipal solid waste management to be a challenge, similarly do the city planners and local administration. The main reason being the difficulty brought about by the complexity in composition of the waste material, no availability of waste minimization technologies and the scarcity of land for landfill sites and their environmental impact (Lal & Singh, 2012). Anyaegbunam (2013) recommend that there is a disposal technique that can convert most of the landfill waste at reduced amount of money to what is being paid on other disposal techniques nowadays, regardless of its form or composition and produce an excess of clean energy, and that technique is called Plasma Gasification which carries a high capability of being economically efficient. According to Young (2010), plasma arc Gasification is a high-temperature pyrolysis process whereby the organics of waste solids (carbon-based materials) are converted into syngas. The syngas can also be sent to gas turbines or reciprocating engines to produce electricity. Few of these plants exist in the world, however there is none in South Africa due to municipal budgetary constraints and lack of evidence for return on investment. Gasification can be described as a thermo-chemical process wherein carbonaceous or carbon-rich feed stocks, for instance tree trimmings or biomass, coal, and petro-coke are transformed into a complex gas containing hydrogen and carbon monoxide (and smaller quantities of carbon dioxide and other trace gases) under high pressure, oxygen exhausted, strong heat and/or steam environments (SRS Energy Solutions, 2016) The problem of electricity shortages continues to increase and communities are unable to cope with the continuous rising electricity bills. It is forecast that electricity demand will grow by approximately 85% and thereby reaching 31 700TWH (terawatt hours) in the year 2035. This growth rate is anticipated at an annual rate of 2.4% of which the economic and population growth will be the driving force, while on the other hand the daily increase of waste at landfill sites poses many problems with regards to the lifespan of the landfill in case green technological disposal processes are not introduced.
- Full Text:
- Date Issued: 2017
Platinum nanoparticles supported on carbon nanodots as anode catalysts for direct alcohol fuel cells
- Gwebu, Sandile Surprise, Nomngongo, Philiswa Nosizo, Mashazi, Philani Nkosinathi, Maxakato, Nobanathi Wendy, Nyokong, Tebello
- Authors: Gwebu, Sandile Surprise , Nomngongo, Philiswa Nosizo , Mashazi, Philani Nkosinathi , Maxakato, Nobanathi Wendy , Nyokong, Tebello
- Date: 2017
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/233118 , vital:50058 , xlink:href="https://doi.org/10.20964/2017.07.09"
- Description: Carbon nanodots (CNDs) were successfully synthesized employing a cheap and green method using oats as a starting material. The Pt/CNDs electrocatalyst was synthesized using carbon nanodots as a reductant and support material without adjusting the pH of the solution. The synthesized materials were characterized using Fourier transform infrared spectroscopy (FTIR), Brunauer-Emmett-Teller Nitrogen adsorption (BET), X-ray photoelectron spectroscopy (XPS), Transmission electron microscopy (TEM), X-ray diffractometry (XRD) and Inductively coupled plasma optical emission spectroscopy (ICP-OES). The FTIR results proved that the synthesized carbon nanodots contain carboxylic acid functional groups which facilitate the attachment of Pt nanoparticles. The BET surface area for carbon nanodots was found to be 312.5 m2 g -1 two times higher than that of commercial carbon. XPS results revealed the composition of the materials and the oxidation states of Pt in Pt/CNDs electrocatalyst. TEM images proved that the materials were of the nanoscale. XRD peaks proved that the carbon nanodots were amorphous and Pt (111) was present in the Pt/CNDs electrocatalyst. ICPOES determined the platinum concentration in Pt/CNDs electrocatalyst to be 8.12%. The electrochemical oxidation of methanol and ethanol were studied by cyclic voltammetry (CV) and chronoamperometry (CA). Cyclic voltammetry results showed that the Pt/CNDs electrocatalyst prepared by this method exhibit superior performance for methanol and ethanol electro-oxidation at room temperature.
- Full Text:
- Date Issued: 2017
Platinum nanoparticles supported on carbon nanodots as anode catalysts for direct alcohol fuel cells
- Authors: Gwebu, Sandile Surprise , Nomngongo, Philiswa Nosizo , Mashazi, Philani Nkosinathi , Maxakato, Nobanathi Wendy , Nyokong, Tebello
- Date: 2017
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/233118 , vital:50058 , xlink:href="https://doi.org/10.20964/2017.07.09"
- Description: Carbon nanodots (CNDs) were successfully synthesized employing a cheap and green method using oats as a starting material. The Pt/CNDs electrocatalyst was synthesized using carbon nanodots as a reductant and support material without adjusting the pH of the solution. The synthesized materials were characterized using Fourier transform infrared spectroscopy (FTIR), Brunauer-Emmett-Teller Nitrogen adsorption (BET), X-ray photoelectron spectroscopy (XPS), Transmission electron microscopy (TEM), X-ray diffractometry (XRD) and Inductively coupled plasma optical emission spectroscopy (ICP-OES). The FTIR results proved that the synthesized carbon nanodots contain carboxylic acid functional groups which facilitate the attachment of Pt nanoparticles. The BET surface area for carbon nanodots was found to be 312.5 m2 g -1 two times higher than that of commercial carbon. XPS results revealed the composition of the materials and the oxidation states of Pt in Pt/CNDs electrocatalyst. TEM images proved that the materials were of the nanoscale. XRD peaks proved that the carbon nanodots were amorphous and Pt (111) was present in the Pt/CNDs electrocatalyst. ICPOES determined the platinum concentration in Pt/CNDs electrocatalyst to be 8.12%. The electrochemical oxidation of methanol and ethanol were studied by cyclic voltammetry (CV) and chronoamperometry (CA). Cyclic voltammetry results showed that the Pt/CNDs electrocatalyst prepared by this method exhibit superior performance for methanol and ethanol electro-oxidation at room temperature.
- Full Text:
- Date Issued: 2017
Political correctness and freedom of expression
- Authors: Embling, Geoffrey
- Date: 2017
- Subjects: Political correctness , Freedom of speech , Political correctness -- South Africa , Freedom of speech -- South Africa , Censorship , Censorship -- South Africa , South Africa -- Politics and government , Political satire, South African , Fanatacism , Toleration
- Language: English
- Type: Thesis , Masters , MA
- Identifier: http://hdl.handle.net/10962/40873 , vital:25035
- Description: A brief history of political correctness is discussed along with various definitions of it, ranging from political correctness being a benign attempt to prevent offense and avert discrimination to stronger views equating it with Communist censorship or branding it as "cultural Marxism". The aim of the research is to discover what political correctness is, how it relates to freedom of expression and what wider implications and effects it has on society. The moral foundations of rights and free speech in particular are introduced in order to set a framework to determine what authority people and governments have to censor others' expression. Different philosophical views on the limits of free speech are discussed, and arguments for and against hate speech are analysed and related to political correctness. The thesis looks at political correctness on university campuses, which involves speech codes, antidiscrimination legislation and changing the Western canon to a more multicultural syllabus. The recent South African university protests involving issues such as white privilege, university fees and rape are discussed and related to political correctness. The thesis examines the role of political correctness in the censorship of humour, it discusses the historical role of satire in challenging dogmatism and it looks at the psychology behind intolerance. Political correctness appeals to tolerance, which is sometimes elevated at the expense of truth. Truth and tolerance are therefore weighed up, along with their altered definitions in today's relativistic society. The last part of the thesis looks at South Africa's unique brand of political correctness, along with Black Economic Empowerment, colonialism and white guilt, and the research concludes that political correctness is a distinct form of censorship which has developed in modern democracies. The new forms of justice and morality seen in political correctness are distortions of left-wing liberalism, which appeal to different values to those of traditional liberalism.
- Full Text:
- Date Issued: 2017
- Authors: Embling, Geoffrey
- Date: 2017
- Subjects: Political correctness , Freedom of speech , Political correctness -- South Africa , Freedom of speech -- South Africa , Censorship , Censorship -- South Africa , South Africa -- Politics and government , Political satire, South African , Fanatacism , Toleration
- Language: English
- Type: Thesis , Masters , MA
- Identifier: http://hdl.handle.net/10962/40873 , vital:25035
- Description: A brief history of political correctness is discussed along with various definitions of it, ranging from political correctness being a benign attempt to prevent offense and avert discrimination to stronger views equating it with Communist censorship or branding it as "cultural Marxism". The aim of the research is to discover what political correctness is, how it relates to freedom of expression and what wider implications and effects it has on society. The moral foundations of rights and free speech in particular are introduced in order to set a framework to determine what authority people and governments have to censor others' expression. Different philosophical views on the limits of free speech are discussed, and arguments for and against hate speech are analysed and related to political correctness. The thesis looks at political correctness on university campuses, which involves speech codes, antidiscrimination legislation and changing the Western canon to a more multicultural syllabus. The recent South African university protests involving issues such as white privilege, university fees and rape are discussed and related to political correctness. The thesis examines the role of political correctness in the censorship of humour, it discusses the historical role of satire in challenging dogmatism and it looks at the psychology behind intolerance. Political correctness appeals to tolerance, which is sometimes elevated at the expense of truth. Truth and tolerance are therefore weighed up, along with their altered definitions in today's relativistic society. The last part of the thesis looks at South Africa's unique brand of political correctness, along with Black Economic Empowerment, colonialism and white guilt, and the research concludes that political correctness is a distinct form of censorship which has developed in modern democracies. The new forms of justice and morality seen in political correctness are distortions of left-wing liberalism, which appeal to different values to those of traditional liberalism.
- Full Text:
- Date Issued: 2017
Population genomics analysis of yellowfin tuna Thunnus albacares off South Africa reveals need for a shifted management boundary
- Authors: Mullins, Rachel Brenna
- Date: 2017
- Subjects: Yellowfin tuna fisheries -- South Africa -- Western Cape , Genomics , Tuna fisheries -- South Africa , Fishery management -- South Africa
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/57819 , vital:26992
- Description: Yellowfin tuna Thunnus albacares is a commercially and economically important fisheries species, which comprises the second largest component of South Africa’s catch of tuna and tuna-like species. Catches of the species off South Africa are treated as two discrete stocks by the two tuna Regional Fisheries Management Organisations (tRFMOs) under whose jurisdictions they fall. Individuals caught off the Western Cape, west of the boundary between the tRFMOs at 20°E, are included in assessment and management of the Atlantic Ocean yellowfin tuna stock by the International Commission for the Conservation of Atlantic Tunas (ICCAT), and those caught east of this boundary are assessed and managed as part of the Indian Ocean stock by the Indian Ocean Tuna Commission (IOTC). The boundary between these stocks is based on the confluence of the two oceans in this region and does not incorporate the population structure of species. For sustainable exploitation of fisheries resources, it is important that the definition of management stocks reflects species’ biological population structure; the fine-scale stock structure of yellowfin tuna off South Africa is therefore a research priority which this study aimed to address by means of population genomics analyses. Yellowfin tuna exhibit shallow genetic differentiation over wide geographic areas, and as such traditional population genetic approaches have limited power in resolving fishery significant population structure in the species. Herein, a population genomic approach was employed, specifically, genome-wide analysis of single nucleotide polymorphisms (SNPs) discovered using a next-generation DNA sequencing approach, to confer (i) increased statistical power to detect neutral structuring reflecting population connectivity patterns and (ii) signatures of local adaptation. The mitochondrial Control Region (mtDNA CR) was also sequenced to compare the resolving power of different approaches and to permit coalescent based analyses of the species evolutionary history in the region. Neutral SNP loci revealed significant structure within the dataset (Fst=0.0043; P<0.0001); partitioning of this differentiation within the dataset indicated significant differentiation between yellowfin tuna from the Western Cape and the Gulf of Guinea in the eastern Atlantic Ocean, with no significant differentiation between individuals from the Western Cape and Western Indian Ocean regions. This indicates two population units wherein there is a separation of the Gulf of Guinea from the remaining samples (Indian Ocean including Western Cape) that are largely derived from a single genetic population. This pattern was also supported by assignment tests. Positive outlier SNPs, exhibiting signatures of diversifying selection, suggest that individuals from these regions may be locally adapted, as well as demographically isolated. The mtDNA CR did not reveal any significant genetic structure among samples (Fst=0.0030; P=0.309), demonstrating the increased resolving power provided by population genomics approaches, but revealed signatures of historical demographic fluctuations associated with glacial cycles. Based on the findings of this study, it is suggested that yellowfin tuna caught off the Western Cape of South Africa are migrants from the Indian Ocean population, exhibiting significant genetic differentiation from the Atlantic Ocean Gulf of Guinea individuals, and should thus be included in the assessment and management of the Indian Ocean stock. It is therefore recommended that the boundary between the Atlantic and Indian Ocean yellowfin tuna stocks, under the mandates of ICCAT and the IOTC respectively, should be shifted to approximately 13.35°E to include all individuals caught in South African waters in the Indian Ocean stock.
- Full Text:
- Date Issued: 2017
- Authors: Mullins, Rachel Brenna
- Date: 2017
- Subjects: Yellowfin tuna fisheries -- South Africa -- Western Cape , Genomics , Tuna fisheries -- South Africa , Fishery management -- South Africa
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/57819 , vital:26992
- Description: Yellowfin tuna Thunnus albacares is a commercially and economically important fisheries species, which comprises the second largest component of South Africa’s catch of tuna and tuna-like species. Catches of the species off South Africa are treated as two discrete stocks by the two tuna Regional Fisheries Management Organisations (tRFMOs) under whose jurisdictions they fall. Individuals caught off the Western Cape, west of the boundary between the tRFMOs at 20°E, are included in assessment and management of the Atlantic Ocean yellowfin tuna stock by the International Commission for the Conservation of Atlantic Tunas (ICCAT), and those caught east of this boundary are assessed and managed as part of the Indian Ocean stock by the Indian Ocean Tuna Commission (IOTC). The boundary between these stocks is based on the confluence of the two oceans in this region and does not incorporate the population structure of species. For sustainable exploitation of fisheries resources, it is important that the definition of management stocks reflects species’ biological population structure; the fine-scale stock structure of yellowfin tuna off South Africa is therefore a research priority which this study aimed to address by means of population genomics analyses. Yellowfin tuna exhibit shallow genetic differentiation over wide geographic areas, and as such traditional population genetic approaches have limited power in resolving fishery significant population structure in the species. Herein, a population genomic approach was employed, specifically, genome-wide analysis of single nucleotide polymorphisms (SNPs) discovered using a next-generation DNA sequencing approach, to confer (i) increased statistical power to detect neutral structuring reflecting population connectivity patterns and (ii) signatures of local adaptation. The mitochondrial Control Region (mtDNA CR) was also sequenced to compare the resolving power of different approaches and to permit coalescent based analyses of the species evolutionary history in the region. Neutral SNP loci revealed significant structure within the dataset (Fst=0.0043; P<0.0001); partitioning of this differentiation within the dataset indicated significant differentiation between yellowfin tuna from the Western Cape and the Gulf of Guinea in the eastern Atlantic Ocean, with no significant differentiation between individuals from the Western Cape and Western Indian Ocean regions. This indicates two population units wherein there is a separation of the Gulf of Guinea from the remaining samples (Indian Ocean including Western Cape) that are largely derived from a single genetic population. This pattern was also supported by assignment tests. Positive outlier SNPs, exhibiting signatures of diversifying selection, suggest that individuals from these regions may be locally adapted, as well as demographically isolated. The mtDNA CR did not reveal any significant genetic structure among samples (Fst=0.0030; P=0.309), demonstrating the increased resolving power provided by population genomics approaches, but revealed signatures of historical demographic fluctuations associated with glacial cycles. Based on the findings of this study, it is suggested that yellowfin tuna caught off the Western Cape of South Africa are migrants from the Indian Ocean population, exhibiting significant genetic differentiation from the Atlantic Ocean Gulf of Guinea individuals, and should thus be included in the assessment and management of the Indian Ocean stock. It is therefore recommended that the boundary between the Atlantic and Indian Ocean yellowfin tuna stocks, under the mandates of ICCAT and the IOTC respectively, should be shifted to approximately 13.35°E to include all individuals caught in South African waters in the Indian Ocean stock.
- Full Text:
- Date Issued: 2017
Population size and development history determine street tree distribution and composition within and between Eastern Cape towns, South Africa
- Gwedla, Nanamhla, Shackleton, Charlie M
- Authors: Gwedla, Nanamhla , Shackleton, Charlie M
- Date: 2017
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/180468 , vital:43392 , xlink:href="https://doi.org/10.1016/j.ufug.2017.04.014"
- Description: Street trees are a common feature of urban nature, providing ecological, economic and social benefits. These public functions are highly dependent on specific design principles, including the composition and diversity of tree species within the urban forest. Consequently, it is important to understand the patterns and correlates of street tree distribution and diversity to assess benefit flows. This requires sampling across and within towns. This paper reports on an assessment of the distribution, composition and diversity of street trees between and within multiple South African towns, and ascertains the correlations between tree density and composition with social contexts. Randomly selected streets were sampled in the affluent, township and low cost housing suburbs of ten Eastern Cape towns. Sixty-nine out of 300 sampled transects had street trees, with 888 trees enumerated, spanning 97 species. Alien tree species accounted for 71% of all the enumerated trees while indigenous trees species accounted for 12%. Tree density and composition were significantly lower in smaller towns and those marginalised during the previous racially-based political regime. Within towns, the poor areas had fewer street trees, with many streets having none. Collaboration and constant communication between the various government departments involved in suburb development is crucial to ensure a more rigorous incorporation of green infrastructure into the building and development plans of new housing developments.
- Full Text:
- Date Issued: 2017
- Authors: Gwedla, Nanamhla , Shackleton, Charlie M
- Date: 2017
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/180468 , vital:43392 , xlink:href="https://doi.org/10.1016/j.ufug.2017.04.014"
- Description: Street trees are a common feature of urban nature, providing ecological, economic and social benefits. These public functions are highly dependent on specific design principles, including the composition and diversity of tree species within the urban forest. Consequently, it is important to understand the patterns and correlates of street tree distribution and diversity to assess benefit flows. This requires sampling across and within towns. This paper reports on an assessment of the distribution, composition and diversity of street trees between and within multiple South African towns, and ascertains the correlations between tree density and composition with social contexts. Randomly selected streets were sampled in the affluent, township and low cost housing suburbs of ten Eastern Cape towns. Sixty-nine out of 300 sampled transects had street trees, with 888 trees enumerated, spanning 97 species. Alien tree species accounted for 71% of all the enumerated trees while indigenous trees species accounted for 12%. Tree density and composition were significantly lower in smaller towns and those marginalised during the previous racially-based political regime. Within towns, the poor areas had fewer street trees, with many streets having none. Collaboration and constant communication between the various government departments involved in suburb development is crucial to ensure a more rigorous incorporation of green infrastructure into the building and development plans of new housing developments.
- Full Text:
- Date Issued: 2017
Population status and habitat use of Indian Ocean humpback dolphins (sousa plumbea) along the south coast of South Africa
- Authors: Conry, Danielle Shanè
- Date: 2017
- Subjects: Sousa -- Population viability analysis -- South Africa Sousa -- Habitat -- South Africa
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/15556 , vital:28269
- Description: Long-lived, top-level predators, such as some marine mammals, serve as important indicators of ecosystem health. Assessing the abundance and habitat use of such marine top predators is essential for the formulation of effective conservation and management actions. There is considerable concern over the viability of small humpback dolphin opulations across a global scale and a number of studies have raised concerns over their vulnerability to extinction. In light of the recent uplisting of Indian Ocean humpback dolphins (Sousa plumbea) to ‘Endangered’ on the South African Red Data list, there is an urgent need for a greater understanding of the abundance and spatial distribution of this species along the South African coastline. Using small vessels as survey platforms between March 2014 and June 2015, this study attempted to determine the abundance, spatial distribution and habitat preferences of Indian Ocean humpback dolphins along 150 km of South Africa’s south coast. A further aim was to assess the utilisation of the current Marine Protected Area network by humpback dolphins along this coastline relative to areas outside of formal protection. Mark-recapture methods applied to photo-identification data produced abundance estimates of 84 individuals (95% CI: 72-115) within the study area for both open and closed models. An average group size of 3.94 individuals (range 1-12; SD = ± 2.82) was observed during the study, indicating a decrease in average group size of ~45 % from a previous assessment in 2002/03. Such a decline in group size could potentially be a result of a change in social structure in response to reduced prey availability. Spatial analyses of humpback dolphin geographic positions, using a kernel density estimator (KDE) and effort-weighted density grid analyses, indicate that the species is unevenly distributed over the coastal zone within the area. Sightings occurred at the highest densities within Buffels Bay and along Goukamma MPA, followed by Plettenberg Bay, Nature’s Valley, and around the Bloukrans, Elandsbos and Groot River East mouths. Habitat preference was assessed using a standard classification-based method and the results indicate a strong preference, in particular, for Dissipative Intermediate Sandy Coast habitat, followed by Very Exposed Rocky Coast, Intermediate Sandy Coast, Estuarine Shore, Mixed Shore and Inshore Reef habitats. Areas of high humpback dolphin densities appear to be associated with these habitat types, especially with Dissipative-Intermediate Sandy Coast habitat. Humpback dolphins were sighted at relatively low densities along stretches of coastline consisting predominately of Exposed Rocky Shore habitat. Long expanses of this habitat type may limit humpback dolphin movements along the coast. The observed patterns in distribution and habitat preferences may be linked to the availability of prey and/or the avoidance of predators. Average sightings per kilometer travelled (SPUE) indicate that the utilisation of the Robberg and Tsitsikamma MPAs by humpback dolphins was low, most likely due to the low availability of sandy coastline in these areas. In contrast, the utilisation of the Goukamma MPA, which is characterised by a high availability of Dissipative-Intermediate Sandy Coast, was very high. The low population numbers and declines in average group size of Indian Ocean humpback dolphins within the study area warrant concern and call for effective conservation and management measures. In light of ever-increasing levels of anthropogenic threats to coastal areas, future research and long-term monitoring of the population is essential to broaden our knowledge of the species and to detect population trends.
- Full Text:
- Date Issued: 2017
- Authors: Conry, Danielle Shanè
- Date: 2017
- Subjects: Sousa -- Population viability analysis -- South Africa Sousa -- Habitat -- South Africa
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/15556 , vital:28269
- Description: Long-lived, top-level predators, such as some marine mammals, serve as important indicators of ecosystem health. Assessing the abundance and habitat use of such marine top predators is essential for the formulation of effective conservation and management actions. There is considerable concern over the viability of small humpback dolphin opulations across a global scale and a number of studies have raised concerns over their vulnerability to extinction. In light of the recent uplisting of Indian Ocean humpback dolphins (Sousa plumbea) to ‘Endangered’ on the South African Red Data list, there is an urgent need for a greater understanding of the abundance and spatial distribution of this species along the South African coastline. Using small vessels as survey platforms between March 2014 and June 2015, this study attempted to determine the abundance, spatial distribution and habitat preferences of Indian Ocean humpback dolphins along 150 km of South Africa’s south coast. A further aim was to assess the utilisation of the current Marine Protected Area network by humpback dolphins along this coastline relative to areas outside of formal protection. Mark-recapture methods applied to photo-identification data produced abundance estimates of 84 individuals (95% CI: 72-115) within the study area for both open and closed models. An average group size of 3.94 individuals (range 1-12; SD = ± 2.82) was observed during the study, indicating a decrease in average group size of ~45 % from a previous assessment in 2002/03. Such a decline in group size could potentially be a result of a change in social structure in response to reduced prey availability. Spatial analyses of humpback dolphin geographic positions, using a kernel density estimator (KDE) and effort-weighted density grid analyses, indicate that the species is unevenly distributed over the coastal zone within the area. Sightings occurred at the highest densities within Buffels Bay and along Goukamma MPA, followed by Plettenberg Bay, Nature’s Valley, and around the Bloukrans, Elandsbos and Groot River East mouths. Habitat preference was assessed using a standard classification-based method and the results indicate a strong preference, in particular, for Dissipative Intermediate Sandy Coast habitat, followed by Very Exposed Rocky Coast, Intermediate Sandy Coast, Estuarine Shore, Mixed Shore and Inshore Reef habitats. Areas of high humpback dolphin densities appear to be associated with these habitat types, especially with Dissipative-Intermediate Sandy Coast habitat. Humpback dolphins were sighted at relatively low densities along stretches of coastline consisting predominately of Exposed Rocky Shore habitat. Long expanses of this habitat type may limit humpback dolphin movements along the coast. The observed patterns in distribution and habitat preferences may be linked to the availability of prey and/or the avoidance of predators. Average sightings per kilometer travelled (SPUE) indicate that the utilisation of the Robberg and Tsitsikamma MPAs by humpback dolphins was low, most likely due to the low availability of sandy coastline in these areas. In contrast, the utilisation of the Goukamma MPA, which is characterised by a high availability of Dissipative-Intermediate Sandy Coast, was very high. The low population numbers and declines in average group size of Indian Ocean humpback dolphins within the study area warrant concern and call for effective conservation and management measures. In light of ever-increasing levels of anthropogenic threats to coastal areas, future research and long-term monitoring of the population is essential to broaden our knowledge of the species and to detect population trends.
- Full Text:
- Date Issued: 2017
Positioning 'the self': comparative case studies of first generation students' academic identities when home meets campus in a rapidly transforming higher education context
- Authors: Alcock, Andrea
- Date: 2017
- Subjects: First-generation college students -- South Africa , First-generation college students -- South Africa -- Case studies , Social perception -- South Africa , Educational equalization -- South Africa , College students -- South Africa -- Attitudes , College students, Black -- South Africa -- Attitudes , College students, Black -- South Africa -- Psychology
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: http://hdl.handle.net/10962/6897 , vital:21198
- Description: This research offers an in-depth view of the self-positioning of a sample of seven first generation students in an extended curriculum programme for Arts and Design at the Durban University of Technology. This comparative case study aims to examine how these participants took up, held or resisted positions, during the transitional process of entering a university. The students' responses were elicited in order to explore the development of student academic identity in this stage of late adolescence. Using positioning theory as an analytical framework, a visual methodology was employed to generate data during photo-elicitation interviews. For these, participants were invited to take metaphorical and non-mimetic photographs, in response to the prompt "Take photographs that show you as a student at home and on campus". Themes that surfaced were examined using positioning theory where the storylines, speech acts and rights and duties form the apex points of the positioning triangle that acts as a framework to analyse the participants' narratives. The study revealed the ways in which participants positioned their home communities and thereby developed their own agency. The majority of the participants used their self-positioning in relation to these home communities to build their academic identities. It was evident in the data that certain role models and peers played a significant part in such self-positioning. The rural to urban migration described by some of the participants indicated that the transition students navigated as they developed their academic identities was profound. The university was often perceived in this process as a powerful structure which offered opportunities but could simultaneously be experienced as alienating. Financial challenges added to the complexity of this experience. The development of student academic identity was evident in positioning statements of the participants and, in some cases, a professional identity was revealed. The analysis indicated that the participants were able to use their self-positioning to overcome many of their challenges through the creation of agential power and resilience. Furthermore the emergence of academic identity seemed to give rise to a positive view of 'the self' in relation to the period of transition to university.
- Full Text:
- Date Issued: 2017
- Authors: Alcock, Andrea
- Date: 2017
- Subjects: First-generation college students -- South Africa , First-generation college students -- South Africa -- Case studies , Social perception -- South Africa , Educational equalization -- South Africa , College students -- South Africa -- Attitudes , College students, Black -- South Africa -- Attitudes , College students, Black -- South Africa -- Psychology
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: http://hdl.handle.net/10962/6897 , vital:21198
- Description: This research offers an in-depth view of the self-positioning of a sample of seven first generation students in an extended curriculum programme for Arts and Design at the Durban University of Technology. This comparative case study aims to examine how these participants took up, held or resisted positions, during the transitional process of entering a university. The students' responses were elicited in order to explore the development of student academic identity in this stage of late adolescence. Using positioning theory as an analytical framework, a visual methodology was employed to generate data during photo-elicitation interviews. For these, participants were invited to take metaphorical and non-mimetic photographs, in response to the prompt "Take photographs that show you as a student at home and on campus". Themes that surfaced were examined using positioning theory where the storylines, speech acts and rights and duties form the apex points of the positioning triangle that acts as a framework to analyse the participants' narratives. The study revealed the ways in which participants positioned their home communities and thereby developed their own agency. The majority of the participants used their self-positioning in relation to these home communities to build their academic identities. It was evident in the data that certain role models and peers played a significant part in such self-positioning. The rural to urban migration described by some of the participants indicated that the transition students navigated as they developed their academic identities was profound. The university was often perceived in this process as a powerful structure which offered opportunities but could simultaneously be experienced as alienating. Financial challenges added to the complexity of this experience. The development of student academic identity was evident in positioning statements of the participants and, in some cases, a professional identity was revealed. The analysis indicated that the participants were able to use their self-positioning to overcome many of their challenges through the creation of agential power and resilience. Furthermore the emergence of academic identity seemed to give rise to a positive view of 'the self' in relation to the period of transition to university.
- Full Text:
- Date Issued: 2017
Post-release evaluation and thermal physiology of the Pereskia stem-wilter, Catorhintha schaffneri (Coreidae), a new biological control agent for Pereskia aculeata (Cactaceae)
- Authors: Muskett, Phillippa Claire
- Date: 2017
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/36094 , vital:24477
- Description: Catorhintha schaffneri Brailovsky and Garcia (Hemiptera: Coreidae) is a biological control agent that was recently accepted for release in South Africa to control Pereskia aculeata Miller (Cactaceae), an invasive creeping cactus. The aim of this thesis was to conduct post-release research to ensure that C. schaffneri is utilised to its full potential. To achieve this aim, and focus release efforts, the thermal physiology of C. schaffneri was investigated to predict where in South Africa the agent is most likely to establish. These predictions were then tested by releasing the agent at field sites with a wide variety of climatic conditions and evaluating establishment success. When invasive plants invade a wide distribution, made up of areas with different climatic conditions, biological control agents may not establish or be effective throughout the invaded distribution. According to the thermal physiology of C. schaffneri, it is most likely to establish and become effective in the subtropical region of South Africa, along the coast of KwaZulu- Natal. Cold winters, or generally low year-round temperatures, may limit establishment in the more temperate areas of South Africa in the Eastern and Western Cape as well as inland in the Highveld region. These predictions can be used to focus release efforts to climatically suitable regions and stop releases in areas where C. schaffneri cannot survive. Predictions based on thermal physiology may not account for all of the variables which affect establishment. To account for other variables, the establishment of C. schaffneri was tested using closely monitored field release studies. During these studies the effect of other variables such as; microclimate temperature, humidity, precipitation, plant quality and release strategy were considered. Low humidity, precipitation and plant quality appear to affect the establishment of C. schaffneri in the subtropical areas of South Africa. The experiment was conducted during a period of drought, and this may have resulted in lower establishment rates. The most successful release strategy for C. schaffneri was the use of multiple, small releases rather than single releases of the same number of individuals. The field based study was therefore able to improve the biological control of P. aculeata by increasing the chance that each release of C. schaffneri results in establishment. The post-release studies presented in this thesis will increase the impact of C. schaffneri by focussing release efforts to climatically suitable sites, releasing at appropriate times of year and releasing the agent in a manner that increases establishment success. Post-release studies, such as those presented here, can make biological control programmes more efficient and effective.
- Full Text:
- Date Issued: 2017
- Authors: Muskett, Phillippa Claire
- Date: 2017
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/36094 , vital:24477
- Description: Catorhintha schaffneri Brailovsky and Garcia (Hemiptera: Coreidae) is a biological control agent that was recently accepted for release in South Africa to control Pereskia aculeata Miller (Cactaceae), an invasive creeping cactus. The aim of this thesis was to conduct post-release research to ensure that C. schaffneri is utilised to its full potential. To achieve this aim, and focus release efforts, the thermal physiology of C. schaffneri was investigated to predict where in South Africa the agent is most likely to establish. These predictions were then tested by releasing the agent at field sites with a wide variety of climatic conditions and evaluating establishment success. When invasive plants invade a wide distribution, made up of areas with different climatic conditions, biological control agents may not establish or be effective throughout the invaded distribution. According to the thermal physiology of C. schaffneri, it is most likely to establish and become effective in the subtropical region of South Africa, along the coast of KwaZulu- Natal. Cold winters, or generally low year-round temperatures, may limit establishment in the more temperate areas of South Africa in the Eastern and Western Cape as well as inland in the Highveld region. These predictions can be used to focus release efforts to climatically suitable regions and stop releases in areas where C. schaffneri cannot survive. Predictions based on thermal physiology may not account for all of the variables which affect establishment. To account for other variables, the establishment of C. schaffneri was tested using closely monitored field release studies. During these studies the effect of other variables such as; microclimate temperature, humidity, precipitation, plant quality and release strategy were considered. Low humidity, precipitation and plant quality appear to affect the establishment of C. schaffneri in the subtropical areas of South Africa. The experiment was conducted during a period of drought, and this may have resulted in lower establishment rates. The most successful release strategy for C. schaffneri was the use of multiple, small releases rather than single releases of the same number of individuals. The field based study was therefore able to improve the biological control of P. aculeata by increasing the chance that each release of C. schaffneri results in establishment. The post-release studies presented in this thesis will increase the impact of C. schaffneri by focussing release efforts to climatically suitable sites, releasing at appropriate times of year and releasing the agent in a manner that increases establishment success. Post-release studies, such as those presented here, can make biological control programmes more efficient and effective.
- Full Text:
- Date Issued: 2017